0$ is no smaller than the maximum achievable rate-function by any scheduling policy for threshold $b-1$. Thus, we are able to achieve a reduction in complexity (from $O(n^{2.5}log n)$ of the hybrid policies to $2n^{2}+2n$ ) with a minimal drop in the delay performance. More importantly, in practice, D-SSG generally has a substantially lower complexity than the hybrid policies that typically have a large constant factor hidden in the $O(cdot)$ notation. Finally, we conduct simu- ations to validate our theoretical results in various scenarios. The simulation results show that in all scenarios we consider, D-SSG not only guarantees a near-optimal rate-function, but also empirically has a similar delay performance to the rate-function delay-optimal policies.\",\n \"Title: Performance analysis of a virtual circuit connection in a high speed ATM WAN using the best effort delivery strategy\\nYear: 1991\\n\\nAbstract: An analytical approach is provided for determining the performance of a virtual circuit connection for data transmission in high speed asynchronous transfer mode (ATM) network buffers at wide area network (WAN) nodes. The analysis assumes that the network operates using the best effort delivery strategy and that the end-to-end virtual circuit is responsible for guaranteeing the integrity of the connection. As the normal Markovian assumptions do not apply, a concise exact solution is impossible to obtain. A hybrid model incorporating finite buffers at the nodes was developed to study the effect on the performance of both link errors and buffer overflow in conjunction with an end-to-end packet loss recovery scheme\",\n \"Title: Video modeling within networks using deterministic smoothing at the source\\nYear: 1994\\n\\nAbstract: Video traffic is expected to become increasingly important with the large scale deployment of broadband ISDN. In the literature, it suggested that smoothing variable bit rate (VBR) video traffic before transmitting it onto the network would help reduce the probability of packet loss. The authors show why deterministic smoothing at the source approximates the minimum achievable loss over the network end-to-end of all possible smoothing schemes. Furthermore, they develop a powerful yet simple analytical technique that can efficiently calculate the loss probability at any point in a network carrying video traffic. They validate the analytical results using traces of actual video segments. The results can be used for admission control and traffic management. They find that in the case of highly correlated traffic such as video, the way to control loss is to ensure that the fraction of time the arrival process exceeds the service process is small\",\n \"Title: A fast suboptimal approach to error concealment in encoded video streams\\nYear: 1997\\n\\nAbstract: In ATM networks cell loss or channel errors can cause data to be dropped in the channel. When digital video is transmitted over these networks one must be able to reconstruct the missing data so that the impact of these errors is minimized. In this paper we describe a Bayesian approach to concealing these errors by post-processing the received data. In a previous paper (see IEEE Proc. Int. Conf. on Image Processing p.49-52, 1996), each frame in the sequence was modeled as a Markov random field, and maximum a posteriori estimates of the missing macroblocks were obtained. However, the maximum a posteriori estimate is not unique, and the algorithm is also computationally intensive. In this paper we demonstrate, that by using median filtering we arrive at a suboptimal estimate. This will allow real-time nearly optimal reconstruction of the missing data\",\n \"Title: New bounds and approximations using extreme value theory for the queue length distribution in high-speed networks\\nYear: 1998\\n\\nAbstract: In this paper we studyP(f Q>x g), the tail of the steady state queue length distribution at a high-speed multiplexer. The tail probability distribution P(f Q>x g) is a funda- mental measure of network congestion and thus important for the ecient design and control of networks. In particu- lar, we focus on the case when the aggregate trac to the multiplexer can be characterized by a stationary Gaussian process. In our approach, a multiplexer is modeled by a fluid queue serving a large number of input processes. We propose two asymptotic upper bounds forP(f Q>x g), and provide several numerical examples to illustrate the tight- ness of these bounds. We also use these bounds to study important properties of the tail probability. Further, we apply these bounds for a large number of non-Gaussian input sources, and validate their performance via simula- tions. We have conducted our simulation study using Im- portance Sampling in order to improve its reliability and to eectively capture rare events. Our analytical study is based on Extreme Value Theory, and therefore dier- ent from the approaches using traditional Markovian and Large Deviations techniques.\",\n \"Title: A reduced-power channel reuse scheme for wireless packet cellular networks\\nYear: 1999\\n\\nAbstract: We present a novel reduced-power channel reuse scheme to improve the spectrum efficiency in wireless packet cellular networks. The basic idea is to reduce intercellular interference and improve the capture probability by an a priori assignment of power levels of channels used in different cells. We formulate and solve an optimal channel-selection problem for our scheme. We find that the optimal policy is in a form of bang-bang control. We illustrate our channel-selection solution by a case study with uniform fairness constraint. We evaluate, via numerical analysis and simulation, both throughput and delay of the new scheme, and compare them with other schemes. We find that our scheme can achieve significant performance improvements, in terms of both the maximum throughput and throughput-delay tradeoff, over a wide range of capture ratio values\",\n \"Title: Optimization Based Rate Control for Communication Networks with Inter-Session Network Coding\\nYear: 2008\\n\\nAbstract: In this paper we develop a distributed rate control algorithm for multiple-unicast-sessions when network coding is allowed. Building on our recent flow-based characterization of network coding, we formulate the problem as a convex optimization problem. The formulation exploits pairwise coding possibilities between any pair of sessions, where the objective function is the sum of the utilities based on the rates supported by each session. With some manipulation on the Lagrangian of the formulated problem, a distributed algorithm is developed with no interaction between intermediate nodes, and each source having the freedom to choose its own utility function. The only information required by the source is the weighted sum of the queue length updates of each link, which can be piggy-backed on the acknowledgment messages. In addition to the optimal rate control algorithm, we propose a decentralized pairwise random coding scheme (PRC) that is optimal when a sufficiently large finite field is used for network coding. The convergence of the rate control algorithm is proved analytically and verified by extensive simulations. Simulations also demonstrate the advantage of our algorithm over the state-of-the-art in terms of throughput and fairness.\",\n \"Title: Delay Analysis for Multi-Hop Wireless Networks\\nYear: 2009\\n\\nAbstract: Abstract—We analyze the delay performance,of a multi- hop wireless network with a fixed route between each source- destination pair. There are arbitrary interference constraints on the set of links that can be served simultaneously at any given time. These interference constraints impose a fundamental lower bound on the delay performance of any scheduling policy for the system. We present a methodology to derive such lower bounds. For the tandem queue network, where the delay optimal policy is known, the expected delay of the optimal policy numerically coincides with the lower bound. We conduct extensive numerical studies to suggest that the average delay of the back-pressure scheduling policy can be made close to the lower bound by using appropriate functions of queue length.\",\n \"Title: Cross-layer optimization for wireless multihop networks with pairwise intersession network coding\\nYear: 2009\\n\\nAbstract: For wireless multi-hop networks with unicast sessions, most coding opportunities involve only two or three sessions as coding across many sessions requires greater transmission power to broadcast the coded symbol to many receivers, which enhances interference. This work shows that with a new flow-based characterization of pairwise intersession network coding (coding across two unicast sessions), an optimal joint coding, scheduling, and rate-control scheme can be devised and implemented using only the binary XOR operation. The new scheduling/rate-control scheme demonstrates provably graceful throughput degradation with imperfect scheduling, which facilitates the design tradeoff between the throughput optimality and computational complexity of different scheduling schemes. Our results show that pairwise intersession network coding improves the throughput of non-coding solutions regardless of whether perfect/imperfect scheduling is used. Both the deterministic and stochastic packet arrivals and departures are considered. This work shows a striking resemblance between pairwise intersession network coding and non-coded solutions, and thus advocates extensions of non-coding wisdoms to their network coding counterpart.\",\n \"Title: Dynamic pricing strategies for social networks in the presence of externalities\\nYear: 2012\\n\\nAbstract: We propose a dynamic pricing strategy for maximizing the revenue of a seller who wishes to sell a divisible service (good) to buyers (agents) embedded in a social network. We investigate the case where the seller can perfectly price discriminate the socially interconnected buyers with positive social influences on each other. We assume that each buyer purchases a non-negative quantity of the service depending both on her internal valuations and on the purchases of her neighbors in the social network. We relax the usual game theoretic assumption of strategic agents and assume a more realistic model of myopic buyers who choose actions that maximize their present utility and do not take into account the effect of their current actions to their future payoffs. We explore the space of dynamic pricing strategies where the seller approaches the buyers sequentially and repeatedly in multiple rounds of a selected order. We propose a dynamic policy for networks with reciprocating agents and compare its performance against an existing static policy that achieves the equilibrium consumption of the buyers. We show that our sequential dynamic pricing policy yields a greater revenue value for the seller and also drives the aggregate social welfare to a higher level than what is achievable by even the best equilibrium. Further, the computational complexity of each new round is cubic in the size of the social network. Our results indicate that dynamics provide a means to improve both seller and buyer objectives even though the strategy is designed specifically to maximize the seller's revenue.\",\n \"Title: Delay Analysis for Wireless Networks With Single Hop Traffic and General Interference Constraints\\nYear: 2010\\n\\nAbstract: We consider a class of wireless networks with general interference constraints on the set of links that can be served simultaneously at any given time. We restrict the traffic to be single-hop, but allow for simultaneous transmissions as long as they satisfy the underlying interference constraints. We begin by proving a lower bound on the delay performance of any scheduling scheme for this system. We then analyze a large class of throughput optimal policies which have been studied extensively in the literature. The delay analysis of these systems has been limited to asymptotic behavior in the heavy traffic regime and order results. We obtain a tighter upper bound on the delay performance for these systems. We use the insights gained by the upper and lower bound analysis to develop an estimate for the expected delay of wireless networks with mutually independent arrival streams operating under the well-known maximum weighted matching (MWM) scheduling policy. We show via simulations that the delay performance of the MWM policy is often close to the lower bound, which means that it is not only throughput optimal, but also provides excellent delay performance.\",\n \"Title: Throughput-Delay Analysis of Random Linear Network Coding for Wireless Broadcasting\\nYear: 2011\\n\\nAbstract: In an unreliable single-hop broadcast network setting, we investigate the throughput and decoding-delay performance of random linear network coding as a function of the coding window size and the network size. Our model consists of a source transmitting packets of a single flow to a set of $n$ users over independent time-correlated erasure channels. The source performs random linear network coding (RLNC) over $k$ (coding window size) packets and broadcasts them to the users. We note that the broadcast throughput of RLNC must vanish with increasing $n$, for any fixed $k$. Hence, in contrast to other works in the literature, we investigate how the coding window size $k$ must scale for increasing $n$. Our analysis reveals that the coding window size of $\\\\\\\\Theta (\\\\\\\\ln (n))$ represents a phase transition rate, below which the throughput converges to zero, and above which, it converges to the broadcast capacity. Further, we characterize the asymptotic distribution of decoding delay and provide approximate expressions for the mean and variance of decoding delay for the scaling regime of $k=\\\\\\\\omega (\\\\\\\\ln (n))$. These asymptotic expressions reveal the impact of channel correlations on the throughput and delay performance of RLNC. We also show that how our analysis can be extended to other rateless block coding schemes such as the LT codes. Finally, we comment on the extension of our results to the cases of dependent channels across users and asymmetric channel model.\",\n \"Title: Optimal SINR based resource allocation for simultaneous energy and information transfer\\nYear: 2013\\n\\nAbstract: In this paper, we study the problem of simultaneous information and power transfer in a wireless multi-user, single hop network. Specifically, we develop an optimal resource allocation algorithm that maximizes the long term average rate of the network while harvesting energy from both the received signal and the interference. We focus on receivers that split the received signal power into two streams; one is fed to an information decoding block and the other is fed to an energy harvester block. We use a weight perturbation Lyapunov approach to optimally schedule data admission and allocate the powers and the energy splitting factors. We show that the designed algorithm achieves O(1/K) of the optimal and requires O(K) data queue and battery size.\",\n \"Title: Deadline constrained scheduling for data aggregation in unreliable sensor networks\\nYear: 2011\\n\\nAbstract: We study the problem of maximizing the aggregated information in a wireless sensor network. We consider a sensor network with a tree topology, where the root corresponds to the sink, and the rest of the network detects an event and transmits data to the sink. We formulate an integer optimization problem that maximizes the aggregated information that reaches the sink under deadline and interference constraints. This framework allows using a variety of error recovery schemes to tackle link unreliability. We show that the optimal solution involves solving a Job Interval Selection Problem (JISP) which is known to be MAX SNP-Hard. We construct a sub-optimal version, and develop a low complexity, distributed optimal solution to this version. We investigate tree structures for which this solution is optimal to the original problem. Our numerical results show that the sub-optimal solution outperforms existing JISP approximation algorithms even for general trees.\",\n \"Title: On optimal dynamic scheduling for sum-queue minimization in trees\\nYear: 2011\\n\\nAbstract: We investigate the problem of minimizing the sum of the queues of all the nodes in a wireless network with a tree topology. Nodes send their packets to the tree's root (sink). We consider a time-slotted system, and a primary interference model. We first consider the case where the root has only one child while the rest of the tree is arbitrary, and provide a causal sample-path delay optimal scheduling policy, i.e., at each time slot, for any traffic arrival pattern, the sum of the queues of all the nodes is minimum among all policies. We are able to fully characterize tree structures for which such policies exist. In particular, when the root has multiple children, there exists a causal sample-path delay optimal policy as long as only one child is not a leaf node. We also show that for any other tree structure there exists no causal sample-path delay optimal policy, thus underscoring the inherent limitation of using sample-path optimality as a performance metric and implying that other weaker metrics of delay performance should be investigated.\",\n \"Title: Maximizing Aggregated Information in Sensor Networks Under Deadline Constraints\\nYear: 2011\\n\\nAbstract: We study the problem of maximizing the aggregated information in sensor networks with deadline constraints. Our model is that of a sensor network that is arranged in the form of a tree topology, where the root corresponds to the sink node, and the rest of the network detects an event and transmits data to the sink over one or more hops. We assume a time-slotted synchronized system and a node-exclusive (also called a primary) interference model. We formulate this problem as an integer optimization problem and show that for unit capacity links, the optimal solution involves solving a Bipartite Maximum Weighted Matching problem at each hop. We propose a polynomial time algorithm that uses only local information at each hop to obtain the optimal solution. Thus, we answer the question of when a node should stop waiting to aggregate data from its predecessors and start transmitting in order to maximize aggregated information within a deadline imposed by the sink. We extend our model to allow for practical considerations such as arbitrary link capacities, and also for multiple overlapping events. Further, we show that our framework is general enough that it can be extended to a number of interesting cases such as incorporating sleep-wake scheduling, minimizing aggregate sensing error, etc.\",\n \"Title: Maximizing Information in Unreliable Sensor Networks Under Deadline and Energy Constraints\\nYear: 2013\\n\\nAbstract: We study the problem of maximizing the information in a wireless sensor network with unreliable links. We consider a sensor network with a tree topology, where the root corresponds to the sink, and the rest of the network detects an event and transmits data to the sink. We formulate a combinatorial optimization problem that maximizes the information that reaches the sink under deadline, energy, and interference constraints. This framework allows using a variety of error recovery schemes to tackle link unreliability. We show that this optimization problem is NP-hard in the strong sense when the input is the maximum node degree of the tree. We then propose a dynamic programming framework for solving the problem exactly, which involves solving a special case of the job interval selection problem (JISP) at each node. Our solution has a polynomial time complexity when the maximum node degree is O (log N ) in a tree with N nodes. For trees with higher node degrees, we further develop a suboptimal solution, which has low complexity and allows distributed implementation. We investigate tree structures for which this solution is optimal to the original problem. The efficiency of the suboptimal solution is further demonstrated through numerical results on general trees.\",\n \"Title: On the efficiency-vs-security tradeoff in the smart grid\\nYear: 2012\\n\\nAbstract: The smart grid is envisioned to significantly enhance the efficiency of energy consumption, by utilizing two-way communication channels between consumers and operators. For example, operators can opportunistically leverage the delay tolerance of energy demands in order to balance the energy load over time, and hence, reduce the total operational cost. This opportunity, however, comes with security threats, as the grid becomes more vulnerable to cyber-attacks. In this paper, we study the impact of such malicious cyber-attacks on the energy efficiency of the grid in a simplified setup. More precisely, we consider a simple model where the energy demands of the smart grid consumers are intercepted and altered by an active attacker before they arrive at the operator, who is equipped with limited intrusion detection capabilities. We formulate the resulting optimization problems faced by the operator and the attacker and propose several scheduling and attack strategies for both parties. Interestingly, our results show that, as opposed to facilitating cost reduction in the smart grid, increasing the delay tolerance of the energy demands potentially allows the attacker to force increased costs on the system. This highlights the need for carefully constructed and robust intrusion detection mechanisms at the operator.\",\n \"Title: Scheduling heterogeneous delay tolerant tasks in smart grid with renewable energy\\nYear: 2012\\n\\nAbstract: The smart grid is the new generation of electricity grid that can efficiently facilitate new distributed sources of energy (e.g., harvested renewable energy), and allow for dynamic electricity price. In this paper, we investigate the cost minimization problem for an end-user, such as a home, community, or a business, which is equipped with renewable energy devices when electrical appliances allow different levels of delay tolerance. The varying price of electricity presents an opportunity to reduce the electricity bill from an end-user's point of view by leveraging the flexibility to schedule operations of various appliances and HVAC systems. We assume that the end user has an energy storage battery as well as an energy harvesting device so that harvested renewable energy can be stored and later used when the price is high. The energy storage battery can also draw energy from the external grid. The problem we formulate here is to minimize the cost of the energy from the external grid while usage of appliances are subject to individual delay constraints and a longterm average delay constraint. The resulting algorithm requires some future information regarding electricity prices, but achieves provable performance without requiring future knowledge of either the power demands or the task arrival process.\",\n \"Title: Managing the adoption of asymmetric bidirectional firewalls: Seeding and mandating\\nYear: 2012\\n\\nAbstract: The security of the Internet can be significantly improved if Internet Service Providers adopt firewalls to monitor traffic entering and leaving access networks. But this process suffers due to `free-riding', and hence, regulatory requirements and `seeding' strategies are required to influence the adoption process. In this paper, we analytically derive the equilibrium adoption levels and relate them to the initial seeding and mandating condition, and explore the issues of incentive alignment across users, firewall developers, and regulators. We define different notions of optimality and analytically develop optimum seeding and mandating policies.\",\n \"Title: Secrecy Outage Capacity of Fading Channels\\nYear: 2012\\n\\nAbstract: This paper considers point-to-point secure communication over flat fading channels under an outage constraint. More specifically, we extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under two different assumptions on the transmitter channel state information (CSI). First, we find the outage secrecy capacity assuming that the transmitter has perfect knowledge of the legitimate and eavesdropper channel gains. In this scenario, the capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes. These keys are stored in a key buffer and later used to secure delay sensitive data using the Vernam's one time pad technique. We then extend our results to the more practical scenario where the transmitter is assumed to know only the legitimate channel gain. Here, our achievability arguments rely on privacy amplification techniques to generate secret key bits. In the two cases, we also characterize the optimal power control policies which, interestingly, turn out to be a judicious combination of channel inversion and the optimal ergodic strategy. Finally, we analyze the effect of key buffer overflow on the overall outage probability.\",\n \"Title: Delay Analysis and Optimality of Scheduling Policies for Multihop Wireless Networks\\nYear: 2011\\n\\nAbstract: We analyze the delay performance of a multihop wireless network with a fixed route between each source-destination pair. We develop a new queue grouping technique to handle the complex correlations of the service process resulting from the multihop nature of the flows. A general set-based interference model is assumed that imposes constraints on links that can be served simultaneously at any given time. These interference constraints are used to obtain a fundamental lower bound on the delay performance of any scheduling policy for the system. We present a systematic methodology to derive such lower bounds. For a special wireless system, namely the clique, we design a policy that is sample-path delay-optimal. For the tandem queue network, where the delay-optimal policy is known, the expected delay of the optimal policy numerically coincides with the lower bound. We conduct extensive numerical studies to suggest that the average delay of the back-pressure scheduling policy can be made close to the lower bound by using appropriate functions of queue length.\",\n \"Title: Non-additive Security Game.\\nYear: 2017\\n\\nAbstract: Strategically allocating resources to protect targets against potential threats in an efficient way is a key challenge facing our society. From the classical interdiction game to the recently proposed Stackelberg Security Game, applying computational game models to the security domain has made a real-world impact on numerous fields including military attack and defense, financial system security, political campaign and civil safeguarding. However, existing methods assume additive utility functions, which are unable to capture the inherent dependencies that exist among different targets in current complex networks. In this paper, we introduce a new security game model, called Non-additive Security Game (NASG). It adopts a non-additive set function to assign the utility to every subset of targets, which completely describes the internal linkage structure of the game. However, both the number of utility functions and the strategies exponentially increase in the number of targets, which poses a significant challenge in developing algorithms to determine the equilibrium strategy. To tackle this problem, we first reduce the NASG to an equivalent zero-sum game and construct a low-rank perturbed game via matrix decomposition and random low-dimensional embedding. Then, we incorporate the above low-rank perturbed game into the Augmented Lagrangian and Coordinate Descent method. Using a series of careful constructions, we show that our method has a total complexity that is nearly linear in the number of utility functions and achieves asymptotic zero error. To the best of our knowledge, the NASG is the first computational game model to investigate dependencies among different targets.\",\n \"Title: Update Or Wait: How To Keep Your Data Fresh\\nYear: 2016\\n\\nAbstract: In this work we study how to manage the freshness of status updates sent from a source to a remote monitor via a network server. A proper metric of data freshness at the monitor is the age-of-information, which is defined as how old the freshest update is since the moment this update was generated at the source. A logical policy is the zero-wait policy, i.e., the source submits a fresh update once the server is free, which achieves the maximum throughput and the minimum average delay. Surprisingly, this zero-wait policy does not always minimize the average age. This motivates us to study how to optimally control the status updates to keep data fresh and to understand when the zero-wait policy is optimal. We introduce a penalty function to characterize the level of \\\"dissatisfaction\\\" on data staleness, and formulate the average age penalty minimization problem as a constrained semi-Markov decision process (SMDP) with an uncountable state space. Despite of the difficulty of this problem, we develop efficient algorithms to find the optimal status update policy. We show that, in many scenarios, the optimal policy is to wait for a certain amount of time before submitting a new update. In particular, the zero-wait policy can be far from the optimum if (i) the penalty function grows quickly with respect to the age, and (ii) the update service times are highly random and positive correlated. To the best of our knowledge, this is the first optimal control policy which is proven to minimize the age-of-information in status update systems.\",\n \"Title: On Delay-Optimal Scheduling in Queueing Systems with Replications.\\nYear: 2016\\n\\nAbstract: In modern computer systems, jobs are divided into short tasks and executed in parallel. Empirical observations in practical systems suggest that the task service times are highly random and the job service time is bottlenecked by the slowest straggling task. One common solution for straggler mitigation is to replicate a task on multiple servers and wait for one replica of the task to finish early. The delay performance of replications depends heavily on the scheduling decisions of when to replicate, which servers to replicate on, and which job to serve first. So far, little is understood on how to optimize these scheduling decisions for minimizing the delay to complete the jobs. In this paper, we present a comprehensive study on delay-optimal scheduling of replications in both centralized and distributed multi-server systems. Low-complexity scheduling policies are designed and are proven to be delay-optimal or near delay-optimal in stochastic ordering among all causal and non-preemptive policies. These theoretical results are established for general system settings and delay metrics that allow for arbitrary arrival processes, arbitrary job sizes, arbitrary due times, and heterogeneous servers with data locality constraints. Novel sample-path tools are developed to prove these results.\",\n \"Title: Achieving Delay Rate-Function Optimality In Ofdm Downlink With Time-Correlated Channels\\nYear: 2016\\n\\nAbstract: There have been recent attempts to develop scheduling schemes for downlink transmission in a single cell of a multi-channel (e.g., OFDM-based) cellular network. These works have been quite promising in that they have developed lowcomplexity index scheduling policies that are delay-optimal (in a large deviation rate-function sense). However, these policies require that the channel is ON or OFF in each time-slot with a fixed probability (i.e., there is no memory in the system), while the reality is that due to channel fading and doppler shift, channels are often time-correlated in these cellular systems. Thus, an important open question is whether one can find simple index scheduling policies that are delay-optimal even when the channels are time-correlated. In this paper, we attempt to answer this question for time-correlated ON/OFF channels. In particular, we show that the class of oldest packets first (OPF) policies that give a higher priority to packets with a large delay is delay rate-function optimal under two conditions: 1) The channel is non-negatively correlated, and 2) The distribution of the OFF period is geometric. We use simulations to further elucidate the theoretical results.\",\n \"Title: Heavy Tails In Queueing Systems: Impact Of Parallelism On Tail Performance\\nYear: 2013\\n\\nAbstract: In this paper we quantify the efficiency of parallelism in systems that are prone to failures and exhibit power law processing delays. We characterize the performance of two prototype schemes of parallelism, redundant and split, in terms of both the power law exponent and exact asymptotics of the delay distribution tail. We also develop the optimal splitting scheme which ensures that split always outperforms redundant.\",\n \"Title: Distributed Signal Decorrelation And Detection In Multi View Camera Networks Using The Vector Sparse Matrix Transform\\nYear: 2015\\n\\nAbstract: This paper introduces the vector sparse matrix transform (vector SMT), a new decorrelating transform suitable for performing distributed processing of high-dimensional signals in sensor networks. We assume that each sensor in the network encodes its measurements into vector outputs instead of scalar ones. The proposed transform decorrelates a sequence of pairs of vector outputs, until these vectors are decorrelated. In our experiments, we simulate distributed anomaly detection by a network of cameras, monitoring a spatial region. Each camera records an image of the monitored environment from its particular viewpoint and outputs a vector encoding the image. Our results, with both artificial and real data, show that the proposed vector SMT transform effectively decorrelates image measurements from the multiple cameras in the network while maintaining low overall communication energy consumption. Since it enables joint processing of the multiple vector outputs, our method provides significant improvements to anomaly detection accuracy when compared with the baseline case when the images are processed independently.\",\n \"Title: Fast Data Retrieval in Cloud Storage Systems\\nYear: 2015\\n\\nAbstract: We are in the midst of a major data revolution. The total data generated by humans from the dawn of civilization until the turn of the new millennium is now being generated every two days. Driven by a wide range of data-intensive devices and applications, this growth is expected to continue its astonishing march, and fuel the development of new and larger data centers. In order to exploit the low-cost services offered by these resource-rich data centers, application developers are pushing computing and storage away from the end-devices and instead deeper into the data-centers. Hence, the end-users' experience is now dependent on the performance of the algorithms used for data retrieval, and job scheduling within the data-centers. In particular, providing low-latency services are critically important to the end-user experience for a wide variety of applications. Our goal has been to develop the analytical foundations and methodologies to enable cloud storage and computing solutions that result in low-latency services. In this talk, I will overview some of the recent research efforts at fast data retrieval in these large-scale data center systems. Specifically, our focus will be on the new tools and techniques required to address these complex issues, the progress made, and the open challenges that remain.\",\n \"Title: Forget the Deadline: Scheduling Interactive Applications in Data Centers\\nYear: 2015\\n\\nAbstract: Many interactive applications running in data centers such as web search, social networks, online gaming, and financial services are delay-sensitive, and often have a deadline. These deadlines vary across users and applications, which makes the job scheduling problem very challenging when the overall system performance needs to be optimized. In this paper, the performance of interest is the total utility gain of multiple interactive jobs, and our objective is to maximize the total utility gain. The interactive jobs arrive to the system over time, and are allowed to be partially executed before their deadlines. We focus on the preemptive scenario, where a job in service can be interrupted by other jobs, and its service can be resumed later. We propose a deadline agnostic scheduler, called ISPEED (Interactive Services with Partial Execution and Deadlines). Being deadline agnostic is an attractive property of ISPEED because data center schedulers are often not privy to individual job deadlines, and thus schedulers that are deadline dependent may not be amenable to implementation. We first prove that ISPEED achieves the maximum total utility when jobs have homogeneous deadlines and their utility functions are non-decreasing and concave. Then, in the case of heterogeneous job deadlines we prove that ISPEED achieves a competitive ratio of 2 + α, where α is a shape parameter for a large class of non-decreasing utility functions. In the special case of α = 0, i.e., The utility functions are concave, ISPEED has a competitive ratio of 2, while no causal scheduler can achieve a competitive ratio smaller than ½5+1/2. Finally, we show through trace-driven simulations that ISPEED outperforms the state-of-the-art schedulers in a wide range of scenarios.\",\n \"Title: Exploiting large system dynamics for designing simple data center schedulers\\nYear: 2015\\n\\nAbstract: The number and size of data centers has seen a rapid growth in the last few years. It is no longer uncommon to see large data centers with thousands or even tens of thousands of machines. Hence, it is critical to develop scalable scheduling mechanisms for processing the enormous number of jobs handled by popular paradigms such as the MapReduce framework. This work explores the possibility of simplifying the scheduling procedure by exploiting the “largeness” of the data center system. Specifically, we consider the problem of minimizing the total flow time of a sequence of jobs under the MapReduce framework, where the jobs arrive over time and need to be processed through both Map and Reduce procedures before leaving the system. We show that any work-conserving scheduler is asymptotically optimal under a wide range of traffic loads, including the heavy traffic limit. Our results are shown for scenarios in which the tasks can be preempted and served in parallel over different machines, as well as scenarios when each task has to be served only on one machine and cannot be preempted. This result implies, somewhat surprisingly, that when we have a large number of machines, there is little to be gained by optimizing beyond ensuring that a scheduler should be work-conserving. For long running applications, we also study the relationship between the number of machines and total running time, and show sufficient conditions to guarantee the asymptotic optimality of work-conserving schedulers. Further, we run extensive simulations, that indeed verify that when the total number of machines is large, state-of-the-art work-conserving schedulers have similar and close-to-optimal delay performance.\",\n \"Title: Provably delay efficient data retrieving in storage clouds\\nYear: 2015\\n\\nAbstract: One key requirement for storage clouds is to be able to retrieve data quickly. Recent system measurements have shown that the data retrieving delay in storage clouds is highly variable, which may result in a long latency tail. One crucial idea to improve the delay performance is to retrieve multiple data copies by using parallel downloading threads. However, how to optimally schedule these downloading threads to minimize the data retrieving delay remains to be an important open problem. In this paper, we develop low-complexity thread scheduling policies for several important classes of data downloading time distributions, and prove that these policies are either delay-optimal or within a constant gap from the optimum delay performance. These theoretical results hold for an arbitrary arrival process of read requests that may contain finite or infinite read requests, and for heterogeneous MDS storage codes that can support diverse storage redundancy and reliability requirements for different data files. Our numerical results show that the delay performance of the proposed policies is significantly better than that of First-Come-First-Served (FCFS) policies considered in prior work.\",\n \"Title: Scheduling In Wireless Networks With Full-Duplex Cut-Through Transmission\\nYear: 2015\\n\\nAbstract: The recent breakthrough in wireless full-duplex communication makes possible a brand new way of multi-hop wireless communication, namely full-duplex cut-through transmission, where for a traffic flow that traverses through multiple links, every node along the route can receive a new packet and simultaneously forward the previously received packet. This wireless transmission scheme brings new challenges in the design of MAC layer algorithms that aim to reap its full benefit. First, the MAC layer rate region of the cut-through enabled network is directly a function of the routing decision, leading to a strong coupling between routing and scheduling. Second, it is unclear how to dynamically form/change cut-through routes based on the traffic rates and patterns. In this work, we introduce a novel method to characterize the interference relationship between links in the network with cut-through transmission, which decouples the routing decision with the scheduling decision and enables a seamless adaptation of traditional half-duplex routing/scheduling algorithm into wireless networks with full-duplex cut-through capabilities. Based on this interference model, a queue-length based CSMA-type scheduling algorithm is proposed, which both leverages the flexibility of full-duplex cut-through transmission and permits distributed implementation.\",\n \"Title: A Game Theoretic Model For Defending Against Stealthy Attacks With Limited Resources\\nYear: 2015\\n\\nAbstract: Stealthy attacks are a major threat to cyber security. In practice, both attackers and defenders have resource constraints that could limit their capabilities. Hence, to develop robust defense strategies, a promising approach is to utilize game theory to understand the fundamental trade-offs involved. Previous works in this direction, however, mainly focus on the single-node case without considering strict resource constraints. In this paper, a game-theoretic model for protecting a system of multiple nodes against stealthy attacks is proposed. We consider the practical setting where the frequencies of both attack and defense are constrained by limited resources, and an asymmetric feedback structure where the attacker can fully observe the states of nodes while largely hiding its actions from the defender. We characterize the best response strategies for both attacker and defender, and study the Nash Equilibria of the game. We further study a sequential game where the defender first announces its strategy and the attacker then responds accordingly, and design an algorithm that finds a nearly optimal strategy for the defender to commit to.\",\n \"Title: Downlink Scheduling Over Markovian Fading Channels.\\nYear: 2016\\n\\nAbstract: We consider the scheduling problem in downlink wireless networks with heterogeneous, Markov-modulated, ON/OFF channels. It is well known that the performance of scheduling over fading channels relies heavily on the accuracy of the available channel state information (CSI), which is costly to acquire. Thus, we consider the CSI acquisition via a practical ARQ-based feedback mechanism whereby channel states are revealed at the end of only scheduled users' transmissions. In the assumed presence of temporally correlated channel evolutions, the desired scheduler must optimally balance the exploitation - exploration tradeoff, whereby it schedules transmissions both to exploit those channels with up-to-date CSI and to explore the current state of those with outdated CSI. In earlier works, Whittle's Index Policy had been suggested as a low-complexity and high-performance solution to this problem. However, analyzing its performance in the typical scenario of statistically heterogeneous channel state processes has remained elusive and challenging, mainly because of the highly coupled and complex dynamics it possesses. In this work, we overcome these difficulties to rigorously establish the asymptotic optimality properties of Whittle's Index Policy in the limiting regime of many users. More specifically: 1) we prove the local optimality of Whittle's Index Policy, provided that the initial state of the system is within a certain neighborhood of a carefully selected state; (2) we then establish the global optimality of Whittle's Index Policy under a recurrence assumption that is verified numerically for our problem. These results establish that Whittle's Index Policy possesses analytically provable optimality characteristics for scheduling over heterogeneous and temporally correlated channels.\",\n \"Title: Low-Complexity Optimal Scheduling over Time-Correlated Fading Channels with ARQ Feedback.\\nYear: 2016\\n\\nAbstract: We investigate the downlink scheduling problem under Markovian ON/OFF fading channels, where the instantaneous channel state information is not directly accessible, but is revealed via ARQ-type feedback. The scheduler can exploit the temporal correlation/channel memory inherent in the Markovian channels to improve network performance. However, designing low-complexity and throughput-optimal algorithms under temporal correlation is a challenging problem. In this paper, we find that under an average number of transmissions constraint, a low-complexity index policy is throughput-optimal. The policy uses Whittle's index value, which was previously used to capture opportunistic scheduling under temporally correlated channels. Our results build on the interesting finding that, under the intricate queue length and channel memory evolutions, the importance of scheduling a user is captured by a simple multiplication of its queue length and Whittle's index value. The proposed queue-based index policy has provably low complexity. Numerical results show that significant throughput gains can be realized by exploiting the channel memory using the proposed low-complexity policy.\",\n \"Title: Understanding the impact of limited channel state information on massive MIMO network performances.\\nYear: 2016\\n\\nAbstract: In recent years, there have been significant efforts on the research and development of Massive MIMO (M-MIMO) technologies at the physical layer. So far, however, the understanding of how M-MIMO could affect the performance of network control and optimization algorithms remains rather limited. In this paper, we focus on analyzing the performance of the queue-length-based joint congestion control and scheduling framework (QCS) over M-MIMO cellular networks with limited channel state information (CSI). Our contributions in this paper are two-fold: i) We characterize the scaling performance of the queue-lengths and show that there exists a phase transitioning phenomenon in the steady-state queue-length deviation respect to the CSI quality (reflected in the number of bits B that represent CSI); and ii) We characterize the congestion control rate scaling performance and show that there also exists a phase transitioning phenomenon in steady-state congestion control rate deviation respect to the CSI quality. Collectively, the findings in this paper advance our understanding of the trade-offs between delay, throughput, and the accuracy/complexity of CSI acquisition in M-MIMO cellular network systems.\",\n \"Title: Anonymous-query based rate control for wireless multicast: approaching optimality with constant feedback.\\nYear: 2016\\n\\nAbstract: For a multicast group of n receivers, existing techniques either achieve high throughput at the cost of prohibitively large (e.g., O(n)) feedback overhead, or achieve low feedback overhead but without either optimal or near-optimal throughput guarantees. Simultaneously achieving good throughput guarantees and low feedback overhead has been an open problem and could be the key reason why wireless multicast has not been successfully deployed in practice. In this paper, we develop a novel anonymous-query based rate control, which approaches the optimal throughput with a constant feedback overhead independent of the number of receivers. In addition to our theoretical results, through implementation on a software-defined ratio platform, we show that the anonymous-query based algorithm achieves low-overhead and robustness in practice.\",\n \"Title: Pricing for past channel state information in multi-channel cognitive radio networks.\\nYear: 2018\\n\\nAbstract: Cognitive Radio (CR) networks have received significant attention as a promising approach to improve the spectrum efficiency of current license-based regulatory system. In CR networks, a Secondary User (SU) can use a spectrum vacancy that can be detected by either sensing-before-transmission or database access. However, it is often difficult to detect a vacant spectrum opportunity because of inaccuracies due to sensing and delays to update and/or the database that holds this information. In this paper, we develop a hybrid detection framework in multi-channel CR networks, where an SU can selectively sense a channel for spectrum vacancy by accessing the spectrum history of Markovian channels. We focus on the value of the channel history information offered by the Primary Provider (PP) of each channel, and consider a market for the information exchange between multiple PPs and SUs. We investigate the interplay between of the PPs and the SUs through their pricing and buying decisions for this information, in the presence of sensing inaccuracy, i.e., false alarm and miss detection.\",\n \"Title: Invited paper: Fast multi-channel Gibbs-sampling for clustering in cloud-based radio access networks\\nYear: 2016\\n\\nAbstract: In this paper, we study how to cluster Remote Radio Heads (RRHs) into Virtual Base-Stations (VBSs) in a Cloud-based Radio Access Network to optimally manage the tradeoff between improving the performance of cell-edge users and maintaining high spatial reuse for the overall system. We develop Gibbs-sampling based algorithms that can find the desirable global VBS configuration from an arbitrarily given set of allowable VBS configurations. While Gibbs-sampling has been used to solve other wireless control problems, its application to VBS clustering faces new challenges both due to the difficulty in estimating the quality of a VBS configuration under rapid channel variations, and due to a new global coupling effect. We leverage Random Matrix Theory to develop a method that can quickly estimate the quality of a VBS configuration based only on average channel statistics. Further, we use perturbation analysis to develop a distributed approximation of the Gibbs sampler to circumvent the global coupling effect, which then allows different parts of the network to search for better VBS configurations in parallel. Our numerical results demonstrate how the proposed algorithm can be used as a general tool to evaluate the system performance under a variety of clustering constraints.\",\n \"Title: Heavy-Ball: A New Approach To Tame Delay And Convergence In Wireless Network Optimization\\nYear: 2016\\n\\nAbstract: The last decade has seen significant advances in optimization-based resource allocation and control approaches for wireless networks. However, the existing work suffer from poor performance in one or more of the metrics of optimality, delay, and convergence speed. To overcome these limitations, in this paper, we introduce a largely overlooked but highly effective heavy-ball optimization method. Based on this heavy-ball technique, we develop a cross-layer optimization framework that offers utility-optimality, fast-convergence, and significant delay reduction. Our contributions are three-fold: i) we propose a heavy-ball joint congestion control and routing/scheduling framework for both single-hop and multi-hop wireless networks; ii) we show that the proposed heavy-ball method offers an elegant three-way trade-off in utility, delay, and convergence, which is achieved under a near index-type simple policy; and more importantly, iii) our work opens the door to an unexplored network control and optimization paradigm that leverages advanced optimization techniques based on \\\"memory/momentum\\\" information.\",\n \"Title: Online Multi-Resource Allocation For Deadline Sensitive Jobs With Partial Values In The Cloud\\nYear: 2016\\n\\nAbstract: In many applications including interactive services and big data analytics, a timely result with a good match is often more valuable than a perfect yet delayed result. This fact can be utilized to improve the total utility gain of a cloud computing platform by allowing partial execution of jobs. A fundamental challenge, however, is that in many real environments, scheduling decisions have to be made online without knowledge about future jobs, which makes it difficult to choose between more valuable jobs with large deadlines and less valuable jobs that are more emergent. Moreover, jobs are often heterogeneous in their utilities, deadlines, and demands for different types of resources. In this paper, we study the problem of online scheduling for deadline-sensitive jobs with concave utility functions that can deliver partial results. We develop efficient online multi-resource allocation algorithms that achieve low competitive ratios for both continuous and discrete job models.\",\n \"Title: Battle of opinions over evolving social networks.\\nYear: 2019\\n\\nAbstract: Social networking environments provide major platforms for the discussion and formation of opinions in diverse areas, including, but not limited to, political discourse, market trends, news, and social movements. Often, these opinions are of a competing nature, e.g., radical vs. peaceful ideologies, correct information vs. misinformation, and one technology vs. another. We study the battles of such competing opinions over evolving social networks. The novelty of our model is that it captures the exposure and adoption dynamics of opinions that account for the preferential and random nature of exposure as well as the persuasion power and persistence of different opinions. We provide a complete characterization of the mean opinion dynamics over time as a function of the initial adoption, as well as the particular exposure, adoption, and persistence dynamics. Our analysis, supported by case studies, reveals the key metrics that govern the spread of opinions and establishes the means to engineer the desired impact of an opinion in the presence of other competing opinions.\",\n \"Title: Delay-Optimal Buffer-Aware Scheduling With Adaptive Transmission.\\nYear: 2017\\n\\nAbstract: In this paper, we aim to obtain the optimal tradeoff between the average delay and the average power consumption in a communication system. In our system, the arrivals occur at each timeslot according to a Bernoulli arrival process, and are buffered at the transmitter waiting to be scheduled. We consider a finite buffer and allow the scheduling decision to depend on the buffer occupancy. In order ...\",\n \"Title: Context-aware application scheduling in mobile systems: what will users do and not do next?\\nYear: 2016\\n\\nAbstract: Usage patterns of mobile devices depend on a variety of factors such as time, location, and previous actions. Hence, context-awareness can be the key to make mobile systems to become personalized and situation dependent in managing their resources. We first reveal new findings from our own Android user experiment: (i) the launching probabilities of applications follow Zipf's law, and (ii) inter-running and running times of applications conform to log-normal distributions. We also find context-dependency in application usage patterns, for which we classify contexts in a personalized manner with unsupervised learning methods. Using the knowledge acquired, we develop a novel context-aware application scheduling framework, CAS that adaptively unloads and preloads background applications in a timely manner. Our trace-driven simulations with 96 user traces demonstrate the benefits of CAS over existing algorithms. We also verify the practicality of CAS by implementing it on the Android platform.\",\n \"Title: Analysis of Connectivity and Capacity in 1-D Vehicle-to-Vehicle Networks.\\nYear: 2016\\n\\nAbstract: A vehicle-to-vehicle (V2V) network is one type of mobile ad hoc network. Due to mobility, the topology in a V2V network is time-varying, which complicates the analysis and evaluation of network performance. In this paper, we model the network as geometric elements of lines and points and analyze the connectivity and capacity of the network using geometric probability. Under the assumption that $n$ vehicles randomly arrive with a Poisson distribution, our analysis shows that the spatial distribution of vehicles within a given distance $D$ , is uniform and that the average number of vehicles to be fully connected is approximately $({1}/{a})( \\\\\\\\log {({1}/{a})} + \\\\\\\\log \\\\\\\\log {({1}/{a})} )$ for $a={R_{T}}/{D}$ , where $R_{T}$ is the maximum transmission range of a vehicle. When a random access scheme is adopted, only $({1}/{2})(1-e^{-2})n$ of links comprised of two adjacent nodes are simultaneously activated, on average, so the expected network capacity increases in a way linearly proportional to $({1}/{2})(1-e^{-2})$ as the number of vehicles increases. Through numerical studies and simulations, we verify the efficacy of our analytical results.\",\n \"Title: Security Game with Non-additive Utilities and Multiple Attacker Resources.\\nYear: 2017\\n\\nAbstract: There has been significant interest in studying security games for modeling the interplay of attacks and defenses on various systems involving critical infrastructure, financial system security, political campaigns, and civil safeguarding. However, existing security game models typically either assume additive utility functions, or that the attacker can attack only one target. Such assumptions lead to tractable analysis, but miss key inherent dependencies that exist among different targets in current complex networks. In this paper, we generalize the classical security game models to allow for non-additive utility functions. We also allow attackers to be able to attack multiple targets. We examine such a general security game from a theoretical perspective and provide a unified view. In particular, we show that each security game is equivalent to a combinatorial optimization problem over a set system ε, which consists of defender's pure strategy space. The key technique we use is based on the transformation, projection of a polytope, and the ellipsoid method. This work settles several open questions in security game domain and significantly extends the state-of-the-art of both the polynomial solvable and NP-hard class of the security game.\",\n \"Title: When to Reset Your Keys: Optimal Timing of Security Updates via Learning.\\nYear: 2017\\n\\nAbstract: Cybersecurity is increasingly threatened by advanced and persistent attacks. As these attacks are often designed to disable a system (or a critical resource, e.g., a user account) repeatedly, it is crucial for the defender to keep updating its security measures to strike a balance between the risk of being compromised and the cost of security updates. Moreover, these decisions often need to be made with limited and delayed feedback due to the stealthy nature of advanced attacks. In addition to targeted attacks, such an optimal timing policy under incomplete information has broad applications in cybersecurity. Examples include key rotation, password change, application of patches, and virtual machine refreshing. However, rigorous studies of optimal timing are rare. Further, existing solutions typically rely on a pre-defined attack model that is known to the defender, which is often not the case in practice. In this work, we make an initial effort towards achieving optimal timing of security updates in the face of unknown stealthy attacks. We consider a variant of the influential FlipIt game model with asymmetric feedback and unknown attack time distribution, which provides a general model to consecutive security updates. The defender's problem is then modeled as a time associative bandit problem with dependent arms. We derive upper confidence bound based learning policies that achieve low regret compared with optimal periodic defense strategies that can only be derived when attack time distributions are known.\",\n \"Title: Delay-Optimal Probabilistic Scheduling In Green Communications With Arbitrary Arrival And Adaptive Transmission\\nYear: 2017\\n\\nAbstract: In this paper, we aim to obtain the optimal delaypower tradeoff and the corresponding optimal scheduling policy for arbitrary i.i.d. arrival process and adaptive transmissions. The number of backlogged packets at the transmitter is known to a scheduler, who has to determine how many backlogged packets to transmit during each time slot. The power consumption is assumed to be convex in transmission rates. Hence, if the scheduler transmits faster, the delay will be reduced but with higher power consumption. To obtain the optimal delay-power tradeoff and the corresponding optimal policy, we model the problem as a Constrained Markov Decision Process (CMDP), where we minimize the average delay given an average power constraint. By steady-state analysis and Lagrangian relaxation, we can show that the optimal tradeoff curve is decreasing, convex, and piecewise linear, and the optimal policy is threshold-based. Based on the revealed properties of the optimal policy, we develop an algorithm to efficiently obtain the optimal tradeoff curve and the optimal policy. The complexity of our proposed algorithm is much lower than a general algorithm based on Linear Programming. We validate the derived results and the proposed algorithm through Linear Programming and simulations.\",\n \"Title: Understanding the Impacts of Limited Channel State Information on Massive MIMO Cellular Network Optimization.\\nYear: 2017\\n\\nAbstract: To support the multi-gigabit per second data rates of 5G wireless networks, there have been significant efforts on the research and development of massive MIMO (M-MIMO) technologies at the physical layer. So far, however, the understanding of how M-MIMO could affect the performance of network control, and optimization algorithms remain rather limited. In this paper, we focus on analyzing the performance of the queue-length-based joint congestion control and scheduling framework over M-MIMO cellular networks with limited channel state information (CSI). Our contributions in this paper are twofold. First, we characterize the scaling performance of the queue-lengths and show that there exists a phase transitioning phenomenon in the steady-state queue-length deviation with respect to the CSI quality (reflected in the number of bits B that represent CSI). Next, we characterize the congestion control rate scaling performance and show that there also exists a phase transitioning phenomenon in steady-state congestion control rate deviation with respect to the CSI quality. Collectively, the findings in this paper advance our understanding of the tradeoffs between delay, throughput, and the accuracy/complexity of CSI acquisition in M-MIMO cellular network systems.\",\n \"Title: CAS: Context-Aware Background Application Scheduling in Interactive Mobile Systems.\\nYear: 2017\\n\\nAbstract: Each individual's usage behavior on mobile devices depends on a variety of factors, such as time, location, and previous actions. Hence, context-awareness provides great opportunities to make the networking and computing capabilities of mobile systems more personalized and more efficient in managing their resources. To this end, we first reveal new findings from our own Android user experiment: 1)...\",\n \"Title: Concurrent Channel Probing and Data Transmission in Full-duplex MIMO Systems.\\nYear: 2017\\n\\nAbstract: An essential step for achieving multiplexing gain in MIMO downlink systems is to collect accurate channel state information (CSI) from the users. Traditionally, CSIs have to be collected before any data can be transmitted. Such a sequential scheme incurs a large feedback overhead, which substantially limits the multiplexing gain especially in a network with a large number of users. In this paper, we propose a novel approach to mitigate the feedback overhead by leveraging the recently developed Full-duplex radios. Our approach is based on the key observation that using Full-duplex radios, when the base-station (BS) is collecting CSI of one user through the uplink channel, it can use the downlink channel to simultaneously transmit data to other (non-interfering) users for which CSIs are already known. By allowing concurrent channel probing and data transmission, our scheme can potentially achieve a higher throughput compared to traditional schemes using Half-duplex radios. The new flexibility introduced by our scheme, however, also leads to fundamental challenges in achieving throughout optimal scheduling. In this paper, we make an initial effort to this important problem by considering a simplified group interference model. We develop a throughput optimal scheduling policy with complexity O((N/I)I), where N is the number of users and I is the number of user groups. To further reduce the complexity, we propose a greedy policy with complexity O(N log N) that not only achieves at least 2/3 of the optimal throughput region, but also outperforms any feasible Half-duplex solutions. We derive the throughput gain offered by Full-duplex under different system parameters and show the advantage of our algorithms through numerical studies.\",\n \"Title: Reward Maximization Under Uncertainty: Leveraging Side-Observations on Networks.\\nYear: 2017\\n\\nAbstract: We study the stochastic multi-armed bandit (MAB) problem in the presence of side-observations across actions that occur as a result of an underlying network structure. In our model, a bipartite graph captures the relationship between actions and a common set of unknowns such that choosing an action reveals observations for the unknowns that it is connected to. This models a common scenario in online social networks where users respond to their friends' activity, thus providing side information about each other's preferences. Our contributions are as follows: 1) We derive an asymptotic lower bound (with respect to time) as a function of the bi-partite network structure on the regret of any uniformly good policy that achieves the maximum long-term average reward. 2) We propose two policies a randomized policy; and a policy based on the well-known upper confidence bound (UCB) policies-both of which explore each action at a rate that is a function of its network position. We show, under mild assumptions, that these policies achieve the asymptotic lower bound on the regret up to a multiplicative factor, independent of the network structure. Finally, we use numerical examples on a real-world social network and a routing example network to demonstrate the benefits obtained by our policies over other existing policies.\",\n \"Title: Towards Fast-Convergence, Low-Delay and Low-Complexity Network Optimization.\\nYear: 2017\\n\\nAbstract: Distributed network optimization has been studied several years. However, we still do not have a good idea of how to design schemes that can simultaneously provide good performance across the dimensions of utility optimality, convergence speed, and delay. To address these challenges, in this paper, we propose a new algorithmic framework with all these metrics approaching optimality. The salient features of our new algorithm are three-fold: (i) fast convergence: it converges with only O(log(1/ε)) iterations, that is the fastest speed among all the existing algorithms; (ii) low delay: it guarantees optimal utility with finite queue length; (iii) simple implementation: the control variables of this algorithm are based on virtual queues that do not require maintaining per-flow information. The new technique builds on a kind of inexact Uzawa method in the Alternating Directional Method of Multiplier. A theoretical contribution of independent interest is a new pathway we provide to prove global and linear convergence rate of Uzawa-ADMM without requiring the full rank assumption of the constraint matrix.\",\n \"Title: iMUTE: Energy-optimal update policy for perishable mobile contents\\nYear: 2017\\n\\nAbstract: Mobile applications that provide ever-changing information such as social media and news feeds applications are designed to consistently update their contents in the background. This operation, often called “prefetching”, provides the users with immediate access to up-to-date contents. However, such updates often result in the unwanted side-effect of draining the battery of mobile devices. It is considered as pure waste when updated contents are not accessed before being renewed. In this paper, we develop an optimal strategy to update the contents in the background under a given energy constraint. The key challenge is to predict when the user will access the contents in a probabilistic manner from the statistics of the accessed patterns in the past. We model our problem as a constrained Markov decision process (C-MDP) and propose to tackle its high complexity with a two-step solution that combines: (1) a threshold-based backward induction algorithm for the Lagrangian relaxation of our C-MDP, and (2) an iterative root finding algorithm, iMUTE (iterative Method for optimal UpdaTe policy with Energy constraint). We prove that iMUTE converges superlinearly to the optimal solution of the original C-MDP under a mild condition. We also experimentally verify that iMUTE outperforms the periodic policy as well as the additive and multiplicative increase policies that are adopted in the Doze mode of Android systems and HUSH, in terms of user experience and energy saving.\",\n \"Title: BiPass: Enabling End-to-End Full Duplex.\\nYear: 2017\\n\\nAbstract: Full duplex techniques can potentially double the channel capacity and achieve lower delays by empowering two radios to simultaneously transmit in thesame frequency band.However, full duplex is only available between two adjacent nodes within the communication range. In this paper, we present BiPass to break this limitation.With the help of full duplex capable relays, weenable simultaneous bidirectional in-band cut-through transmissions between two far apart nodes, so they can do full duplex communications as if they were within each other's transmission range.To design such a system, we analyze interference patterns and propose a loop-back interference cancellation strategy. We identify the power amplification problem at relay nodes and develop an algorithm to solve it. We also develop a routing algorithm, an opportunistic forwarding scheme, and a real-time feedback strategy to leverage this system in ad-hoc networks.To evaluate the real world performance of BiPass, we build a prototype and conduct experiments using software defined radios. We show that BiPass can achieve 1.6x median throughput gain over state-of-the-art one-way cut-through systems, and 4.09x gain over the decode-and-forward scheme. Our simulations further reveal that even when the data traffic is not bidirectional, BiPass has 1.36x throughput gain and 47\\\\% delay reduction overone-way cut-through systemsin large networks.\",\n \"Title: On Resource Pooling and Separation for LRU Caching.\\nYear: 2018\\n\\nAbstract: Caching systems using the Least Recently Used (LRU) principle have now become ubiquitous. A fundamental question for these systems is whether the cache space should be pooled together or divided to serve multiple flows of data item requests in order to minimize the miss probabilities. In this paper, we show that there is no straight yes or no answer to this question, and depends on complex combinations of critical factors, including, e.g., request rates, overlapped data items across different request flows, data item popularities and their sizes. To this end, we characterize the performance of multiple flows of data item requests under resource pooling and separation when the cache size is large. Analytically we show that it is asymptotically optimal to jointly serve multiple flows if their data item sizes and popularity distributions are similar, and their arrival rates do not differ significantly; the self-organizing property of LRU caching automatically optimizes the resource allocation among them asymptotically. Otherwise, separating these flows could be better, e.g., when data sizes vary significantly. We also quantify critical points beyond which resource pooling is better than separation for each of the flows when the overlapped data items exceed certain levels. These results provide new insights on the performance of caching systems.\",\n \"Title: Information Directed Sampling for Stochastic Bandits with Graph Feedback\\nYear: 2018\\n\\nAbstract: We consider stochastic multi-armed bandit problems with graph feedback, where the decision maker is allowed to observe the neighboring actions of the chosen action. We allow the graph structure to vary with time and consider both deterministic and Erdos-Renyi random graph models. For such a graph feedback model, we first present a novel analysis of Thompson sampling that leads to tighter performance bound than existing work. Next, we propose new Information Directed Sampling based policies that are graph-aware in their decision making. Under the deterministic graph case, we establish a Bayesian regret bound for the proposed policies that scales with the clique cover number of the graph instead of the number of actions. Under the random graph case, we provide a Bayesian regret bound for the proposed policies that scales with the ratio of the number of actions over the expected number of observations per iteration. To the best of our knowledge, this is the first analytical result for stochastic bandits with random graph feedback. Finally, using numerical evaluations, we demonstrate that our proposed IDS policies outperform existing approaches, including adaptions of upper confidence bound, epsilon-greedy and Exp3 algorithms.\",\n \"Title: A Change-Detection Based Framework for Piecewise-Stationary Multi-Armed Bandit Problem\\nYear: 2018\\n\\nAbstract: The multi-armed bandit problem has been extensively studied under the stationary assumption. However in reality, this assumption often does not hold because the distributions of rewards themselves may change over time. In this paper, we propose a change-detection (CD) based framework for multi-armed bandit problems under the piecewise-stationary setting, and study a class of change-detection based UCB (Upper Confidence Bound) policies, CD-UCB, that actively detects change points and restarts the UCB indices. We then develop CUSUM-UCB and PHT-UCB, that belong to the CD-UCB class and use cumulative sum (CUSUM) and Page-Hinkley Test (PHT) to detect changes. We show that CUSUM-UCB obtains the best known regret upper bound under mild assumptions. We also demonstrate the regret reduction of the CD-UCB policies over arbitrary Bernoulli rewards and Yahoo! datasets of webpage click-through rates.\",\n \"Title: Minimizing the Age of Information Through Queues\\nYear: 2017\\n\\nAbstract: In this paper, we investigate scheduling policies that minimize the age of information in single-hop queueing systems. We propose a Last-Generated, First-Serve (LGFS) scheduling policy, in which the packet with the earliest generation time is processed with the highest priority. If the service times are \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i.i.d.</italic>\\n exponentially distributed, the preemptive LGFS policy is proven to be age-optimal in a stochastic ordering sense. If the service times are \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i.i.d.</italic>\\n and satisfy a New-Better-than-Used (NBU) distributional property, the non-preemptive LGFS policy is shown to be within a constant gap from the optimum age performance. These age-optimality results are quite general: (i) they hold for arbitrary packet generation times and arrival times (including out-of-order packet arrivals); (ii) they hold for multi-server packet scheduling with the possibility of replicating a packet over multiple servers; (iii) and they hold for minimizing not only the time-average age and mean peak age, but also for minimizing the age stochastic process and any non-decreasing functional of the age stochastic process. If the packet generation time is equal to the packet arrival time, the LGFS policies reduce to the Last-Come, First-Serve (LCFS) policies. Hence, the age optimality results of LCFS-type policies are also established.\",\n \"Title: Energy-Efficient Power and Bandwidth Allocation in an Integrated Sub-6 GHz - Millimeter Wave System.\\nYear: 2017\\n\\nAbstract: In mobile millimeter wave (mmWave) systems, energy is a scarce resource due to the large losses in the channel and high energy usage by analog-to-digital converters (ADC), which scales with bandwidth. In this paper, we consider a communication architecture that integrates the sub-6 GHz and mmWave technologies in 5G cellular systems. In order to mitigate the energy scarcity in mmWave systems, we investigate the rate-optimal and energy-efficient physical layer resource allocation jointly across the sub-6 GHz and mmWave interfaces. First, we formulate an optimization problem in which the objective is to maximize the achievable sum rate under power constraints at the transmitter and receiver. Our formulation explicitly takes into account the energy consumption in integrated-circuit components, and assigns the optimal power and bandwidth across the interfaces. We consider the settings with no channel state information and partial channel state information at the transmitter and under high and low SNR scenarios. Second, we investigate the energy efficiency (EE) defined as the ratio between the amount of data transmitted and the corresponding incurred cost in terms of power. We use fractional programming and Dinkelbachu0027s algorithm to solve the EE optimization problem. Our results prove that despite the availability of huge bandwidths at the mmWave interface, it may be optimal (in terms of achievable sum rate and energy efficiency) to utilize it partially. Moreover, depending on the sub-6 GHz and mmWave channel conditions and total power budget, it may be optimal to activate only one of the interfaces.\",\n \"Title: Designing Low-Complexity Heavy-Traffic Delay-Optimal Load Balancing Schemes: Theory to Algorithms.\\nYear: 2017\\n\\nAbstract: We establish a unified analytical framework for designing load balancing algorithms that can simultaneously achieve low latency, low complexity, and low communication overhead. We first propose a general class ∏ of load balancing policies and prove that they are both throughput optimal and heavy-traffic delay optimal. This class ∏ includes popular policies such as join-shortest-queue (JSQ) and power-of-d as special cases, but not the recently proposed join-idle-queue (JIQ) policy. In fact, we show that JIQ is not heavy-traffic delay optimal even for homogeneous servers. By exploiting the flexibility offered by the class ∏, we design a new load balancing policy called join-below-threshold (JBT-d), in which the arrival jobs are preferentially assigned to queues that are no greater than a threshold, and the threshold is updated infrequently. JBT-d has several benefits: (i) JBT-d belongs to the class ∏ and hence is throughput optimal and heavy-traffic delay optimal. (ii) JBT-d has zero dispatching delay, like JIQ and other pull-based policies, and low message overhead due to infrequent threshold updates. (iii) Extensive simulations show that JBT-d has good delay performance, comparable to the JSQ policy in various system settings.\",\n \"Title: High Throughput Low Delay Wireless Multicast via Multi-Channel Moving Window Codes.\\nYear: 2018\\n\\nAbstract: A fundamental challenge in wireless multicast has been how to simultaneously achieve high-throughput and low delay for reliably serving a large number of users. In this paper, we show how to harness substantial throughput and delay gains by exploiting multi-channel resources. We develop a new scheme called Multi-Channel Moving Window Codes (MC-MWC) for multi-channel multi-session wireless multicast. The salient features of MC-MWC are three-fold. (i) High throughput: we show that MC-MWC achieves order-optimal throughput in the many user many-channel asymptotic regime. Moreover, the number of channels required by a conventional channel-allocation based scheme is shown to be doubly-exponentially larger than that required by MC-MWC. (ii) Low delay: using large deviations theory, we show that the delay of MC-MWC decreases linearly with the number of channels, while the delay reduction of conventional schemes is no more than a finite constant. (iii) Low feedback overhead: the feedback overhead of MC-MWC is a constant that is independent of both the number of receivers in each session and the number of sessions in the network. Finally, our trace-driven simulation and numerical results validate the analytical results and show that the implementation complexity of MC-MWC is low.\",\n \"Title: The Age of Information in Multihop Networks.\\nYear: 2017\\n\\nAbstract: Information updates in multihop networks such as Internet of Things (IoT) and intelligent transportation systems have received significant recent attention. In this paper, we minimize the age of a single information flow in interference-free multihop networks. When preemption is allowed and the packet transmission times are exponentially distributed, we prove that a preemptive last-generated, first-served (LGFS) policy results in smaller age processes across all nodes in the network than any other causal policy (in a stochastic ordering sense). In addition, for the class of new-better-than-used (NBU) distributions, we show that the non-preemptive LGFS policy is within a constant age gap from the optimum average age. In contrast, our numerical result shows that the preemptive LGFS policy can be very far from the optimum for some NBU transmission time distributions. Finally, when preemption is prohibited and the packet transmission times are arbitrarily distributed, the non-preemptive LGFS policy is shown to minimize the age processes across all nodes in the network among all work-conserving policies (again in a stochastic ordering sense). Interestingly, these results hold under quite general conditions, including 1) arbitrary packet generation and arrival times, and 2) for minimizing both the age processes in stochastic ordering and any non-decreasing functional of the age processes.\",\n \"Title: Efficient Beam Alignment in Millimeter Wave Systems Using Contextual Bandits\\nYear: 2018\\n\\nAbstract: In this paper, we investigate the problem of beam alignment in millimeter wave (mmWave) systems, and design an optimal algorithm to reduce the overhead. Specifically, due to directional communications, the transmitter and receiver beams need to be aligned, which incurs high delay overhead since without a priori knowledge of the transmitter/receiver location, the search space spans the entire angular domain. This is further exacerbated under dynamic conditions (e.g., moving vehicles) where the access to the base station (access point) is highly dynamic with intermittent on-off periods, requiring more frequent beam alignment and signal training. To mitigate this issue, we consider an online stochastic optimization formulation where the goal is to maximize the directivity gain (i.e., received energy) of the beam alignment policy within a time period. We exploit the inherent correlation and unimodality properties of the model, and demonstrate that contextual information improves the performance. To this end, we propose an equivalent structured Multi-Armed Bandit model to optimally exploit the exploration-exploitation tradeoff. In contrast to the classical MAB models, the contextual information makes the lower bound on regret (i.e., performance loss compared with an oracle policy) independent of the number of beams. This is a crucial property since the number of all combinations of beam patterns can be large in transceiver antenna arrays, especially in massive MIMO systems. We further provide an asymptotically optimal beam alignment algorithm, and investigate its performance via simulations.\",\n \"Title: Out-of-Band Millimeter Wave Beamforming and Communications to Achieve Low Latency and High Energy Efficiency in 5G Systems.\\nYear: 2018\\n\\nAbstract: Communications in the millimeter wave (mmWave) band faces significant challenges due to variable channels, intermittent connectivity, and high energy usage. Moreover, speeds for electronic processing of data is of the same order as typical rates for mmWave interfaces, making the use of complex algorithms for tracking channel variations and adjusting resources impractical. In order to mitigate some...\",\n \"Title: Coded Sparse Matrix Multiplication.\\nYear: 2018\\n\\nAbstract: In a large-scale and distributed matrix multiplication problem $C=A^{intercal}B$, where $Cinmathbb{R}^{rtimes t}$, the coded computation plays an important role to effectively deal with stragglers (distributed computations that may get delayed due to few slow or faulty processors). However, existing coded schemes could destroy the significant sparsity that exists in large-scale machine learning problems, and could result in much higher computation overhead, i.e., $O(rt)$ decoding time. In this paper, we develop a new coded computation strategy, we call emph{sparse code}, which achieves near emph{optimal recovery threshold}, emph{low computation overhead}, and emph{linear decoding time} $O(nnz(C))$. We implement our scheme and demonstrate the advantage of the approach over both uncoded and current fastest coded strategies.\",\n \"Title: Degree of Queue Imbalance: Overcoming the Limitation of Heavy-traffic Delay Optimality in Load Balancing Systems.\\nYear: 2018\\n\\nAbstract: In this paper, we argue that heavy-traffic delay optimality is a coarse metric that does not necessarily imply good delay performance. Specifically, we show that any load balancing scheme is heavytraffic delay optimal as long as it satisfies a fairly weak condition. This condition only requires that in the long-term the dispatcher favors, even slightly, shorter queues over longer queues. Hence, the empirical delay performance of heavy-traffic delay optimal schemes can range from very good (that of join-shortest-queue) to very bad (arbitrarily close to the performance of random routing). To overcome this limitation,we introduce a newmetric called degree of queue imbalance, which measures the queue length difference between all the servers in steady-state. Given a heavy-traffic delay optimal load balancing scheme, we can characterize the resultant degree of queue imbalance. This, in turn, allows us to explicitly differentiate between good and poor load balancing schemes. Thus, this paper implies that good load balancing should not only be designed to be heavy-traffic delay optimal, but also have a low degree of queue imbalance.\",\n \"Title: An Online Algorithm For Power-Proportional Data Centers With Switching Cost\\nYear: 2018\\n\\nAbstract: Recent studies have shown that power-proportional data centers can save energy cost by dynamically \\\"right-sizing\\\" the data centers based on real-time workload. More servers are activated when the workload increases while some servers can be put into the sleep mode during periods of low load. In this paper, we revisit the dynamic right-sizing problem for heterogeneous data centers with various operational cost and switching cost. We propose a new online algorithm based on a regularization technique, which achieves a better competitive ratio compared to the state-of-the-art greedy algorithm in [17]. We further introduce a switching cost offset into the model and extend our algorithm to this new setting. Simulations based on real workload and renewable energy traces show that our algorithms outperform the greedy algorithm in both settings.\",\n \"Title: Qos-aware predictive rate allocation over heterogeneous wireless interfaces\\nYear: 2018\\n\\nAbstract: The rapid growth of mobile data traffic is straining cellular networks. A natural approach to alleviate cellular networks congestion is to use, in addition to the cellular interface, secondary interfaces such as WiFi, Dynamic spectrum and mmWave to aid cellular networks in handling mobile traffic. The fundamental question now becomes: How should traffic be distributed over different interfaces, taking into account different application QoS requirements and the diverse nature of radio interfaces. To this end, we propose the Discounted Rate Utility Maximization (DRUM) framework with interface costs as a means to quantify application preferences in terms of throughput, delay, and cost. The flow rate allocation problem can be formulated as a convex optimization problem. However, solving this problem requires non-causal knowledge of the time-varying capacities of all radio interfaces. To this end, we propose an online predictive algorithm that exploits the predictability of wireless connectivity for a small look-ahead window w. We show that, under some mild conditions, the proposed algorithm achieves a constant competitive ratio independent of the time horizon T. Furthermore, the competitive ratio approaches 1 as the prediction window increases. We also propose another predictive algorithm based on the \\\"Receding Horizon Control\\\" principle from control theory that performs very well in practice. Numerical simulations serve to validate our formulation, by showing that under the DRUM framework: the more delay-tolerant the flow, the less it uses the cellular network, preferring to transmit in high rate bursts over the secondary interfaces. Conversely, delay-sensitive flows consistently transmit irrespective of different interfaces' availability. Simulations also show that the proposed online predictive algorithms have a near-optimal performance compared to the offline prescient solution under all considered scenarios.\",\n \"Title: Towards Practical Constrained Monotone Submodular Maximization.\\nYear: 2018\\n\\nAbstract: We design new algorithms for maximizing a monotone non-negative submodular function under various constraints, which improve the state-of-the-art in time complexity and/or performance guarantee. We first investigate the cardinality constrained submodular maximization problem that has been widely studied for about four decades. We design an $(1-frac{1}{e}-varepsilon)$-approximation algorithm that makes $O(ncdot max {varepsilon^{-1},loglog k })$ queries. To the best of our knowledge, this is the fastest known algorithm. We further answer the open problem on finding a lower bound on the number of queries. We show that, no (randomized) algorithm can achieve a ratio better than $(frac{1}{2}+Theta(1))$ with $o(frac{n}{log queries. The acceleration above is achieved by our emph{Adaptive Decreasing Threshold} (ADT) algorithm. Based on ADT, we study the $p$-system and $d$ knapsack constrained maximization problem. We show that an $(1/(p+frac{7}{4}d+1)-varepsilon)$-approximate solution can be computed via $O(frac{n}{varepsilon}log frac{n}{varepsilon}max{log frac{1}{varepsilon},loglog n})$ queries. Note that it improves the state of the art in both time complexity and approximation ratio. We also show how to improve the ratio for a single knapsack constraint via $O(ncdot max {varepsilon^{-1},loglog k })$ queries. For maximizing a submodular function with curvature $kappa$ under matroid constraint, we show an $(1-frac{kappa}{e}-varepsilon)$-approximate algorithm that uses $tilde{O}(nk)$ value oracle queries. Our ADT could be utilized to obtain faster algorithms in other problems. To prove our results, we introduce a general characterization between randomized complexity and deterministic complexity of approximation algorithms that could be used in other problems and may be interesting in its own right.\",\n \"Title: Fundamental Limits of Coded Linear Transform.\\nYear: 2018\\n\\nAbstract: In large scale distributed linear transform problems, coded computation plays an important role to effectively deal with stragglers (distributed computations that may get delayed due to few slow or faulty processors). We propose a coded computation strategy, referred to as diagonal code, that achieves the optimum recovery threshold and the optimum computation load. This is the first code that simultaneously achieves two-fold optimality in coded distributed linear transforms. Furthermore, by leveraging the idea from random proposal graph theory, we design two random codes that can guarantee optimum recovery threshold with high probability but with much less computation load. These codes provide order-wise improvement over the state-of-the-art. Moreover, the experimental results show significant improvement compared to both uncoded and existing coding schemes.\",\n \"Title: UCBoost: A Boosting Approach to Tame Complexity and Optimality for Stochastic Bandits.\\nYear: 2018\\n\\nAbstract: In this work, we address the open problem of finding low-complexity near-optimal multi-armed bandit algorithms for sequential decision making problems. Existing bandit algorithms are either sub-optimal and computationally simple (e.g., UCB1) or optimal and computationally complex (e.g., kl-UCB). We propose a boosting approach to Upper Confidence Bound based algorithms for stochastic bandits, that we call UCBoost. Specifically, we propose two types of UCBoost algorithms. We show that UCBoost($D$) enjoys $O(1)$ complexity for each arm per round as well as regret guarantee that is $1/e$-close to that of the kl-UCB algorithm. We propose an approximation-based UCBoost algorithm, UCBoost($epsilon$), that enjoys a regret guarantee $epsilon$-close to that of kl-UCB as well as $O(log(1/epsilon))$ complexity for each arm per round. Hence, our algorithms provide practitioners a practical way to trade optimality with computational complexity. Finally, we present numerical results which show that UCBoost($epsilon$) can achieve the same regret performance as the standard kl-UCB while incurring only $1%$ of the computational cost of kl-UCB.\",\n \"Title: Incentivizing Truthful Data Quality for Quality-Aware Mobile Data Crowdsourcing.\\nYear: 2018\\n\\nAbstract: Mobile data crowdsourcing has found a broad range of applications (e.g., spectrum sensing, environmental monitoring) by leveraging the \\\"wisdom\\\" of a potentially large crowd of \\\"workers\\\" (i.e., mobile users). A key metric of crowdsourcing is data accuracy, which relies on the quality of the participating workers' data (e.g., the probability that the data is equal to the ground truth). However, the data quality of a worker can be its own private information (which the worker learns, e.g., based on its location) that it may have incentive to misreport, which can in turn mislead the crowdsourcing requester about the accuracy of the data. This issue is further complicated by the fact that the worker can also manipulate its effort made in the crowdsourcing task and the data reported to the requester, which can also mislead the requester. In this paper, we devise truthful crowdsourcing mechanisms for Quality, Effort, and Data Elicitation (QEDE), which incentivize strategic workers to truthfully report their private worker quality and data to the requester, and make truthful effort as desired by the requester. The truthful design of the QEDE mechanisms overcomes the lack of ground truth and the coupling in the joint elicitation of worker quality, effort, and data. Under the QEDE mechanisms, we characterize the socially optimal and the requester's optimal task assignments, and analyze their performance. We show that the requester's optimal assignment is determined by the largest \\\"virtual valuation\\\" rather than the highest quality among workers, which depends on the worker's quality and the quality's distribution. We evaluate the QEDE mechanisms using simulations which demonstrate the truthfulness of the mechanisms and the performance of the optimal task assignments.\",\n \"Title: Analysis Of Thompson Sampling For Graphical Bandits Without The Graphs\\nYear: 2018\\n\\nAbstract: We study multi-armed bandit problems with graph feedback, in which the decision maker is allowed to observe the neighboring actions of the chosen action, in a setting where the graph may vary over time and is never fully revealed to the decision maker. We show that when the feedback graphs are undirected, the original Thompson Sampling achieves the optimal (within logarithmic factors) regret (O) over tilde(root beta(0)(G)T) over time horizon T, where beta(0)(G) is the average independence number of the latent graphs. To the best of our knowledge, this is the first result showing that the original Thompson Sampling is optimal for graphical bandits in the undirected setting. A slightly weaker regret bound of Thompson Sampling in the directed setting is also presented. To fill this gap, we propose a variant of Thompson Sampling, that attains the optimal regret in the directed setting within a logarithmic factor. Both algorithms can be implemented efficiently and do not require the knowledge of the feedback graphs at any time.\",\n \"Title: PAC Ranking from Pairwise and Listwise Queries: Lower Bounds and Upper Bounds.\\nYear: 2018\\n\\nAbstract: This paper explores the adaptive (active) PAC (probably approximately correct) top-$k$ ranking (i.e., top-$k$ item selection) and total ranking problems from $l$-wise ($lgeq 2$) comparisons under the multinomial logit (MNL) model. By adaptively choosing sets to query and observing the noisy output of the most favored item of each query, we want to design ranking algorithms that recover the top-$k$ or total ranking using as few queries as possible. For the PAC top-$k$ ranking problem, we derive a lower bound on the sample complexity (aka number of queries), and propose an algorithm that is sample-complexity-optimal up to an $O(log(k+l)/log{k})$ factor. When $l=2$ (i.e., pairwise comparisons) or $l=O(poly(k))$, this algorithm matches the lower bound. For the PAC total ranking problem, we derive a tight lower bound, and propose an algorithm that matches the lower bound. When $l=2$, the MNL model reduces to the popular Plackett-Luce (PL) model. In this setting, our results still outperform the state-of-the-art both theoretically and numerically. We also compare our algorithms with the state-of-the-art using synthetic data as well as real-world data to verify the efficiency of our algorithms.\",\n \"Title: Finding minimum node separators: A Markov chain Monte Carlo method.\\nYear: 2018\\n\\nAbstract: In networked systems such as communication networks or power grids, graph separation from node failures can damage the overall operation severely. One of the most important goals of network attackers is thus to separate nodes so that the sizes of connected components become small. In this work, we consider the problem of finding a minimum α-separator, that partitions the graph into connected components of sizes at most αn, where n is the number of nodes. To solve the α-separator problem, we develop a random walk algorithm based on Metropolis chain. We characterize the conditions for the first passage time (to find an optimal solution) of our algorithm. We also find an optimal cooling schedule, under which the random walk converges to an optimal solution almost surely. Furthermore, we generalize our algorithm to non-uniform node weights. We show through extensive simulations that the first passage time is less than O(n3), thereby validating our analysis. The solution found by our algorithm allows us to identify the weakest points in the network that need to be strengthened. Simulations in real topologies show that attacking a dense area is often not an efficient solution for partitioning a network into small components.\",\n \"Title: A Near-Optimal Control Policy in Cloud Systems with Renewable Sources and Time-Dependent Energy Price\\nYear: 2018\\n\\nAbstract: The cost of energy usage is of significant concern in cloud/data center systems that support a large number of servers. A simple way to reduce energy consumption and the electricity bill is to turn some of the servers off during periods of under utilization. However, turning a server back on typically consumes a lot of energy. Another way to reduce the energy cost is to equip cloud systems with renewable resources and batteries. Most works in the literature have focused on one or the other approach. In this work, we propose a joint server on-off and energy control policy, which determines the servers' on-off status, as well as the energy purchasing behavior, by taking electricity price, renewable resources, possible future tasks and turn-on cost into account. The server on-off control component is proved to be optimal in terms of energy consumption minimization. The joint policy is shown to be arbitrarily close to the optimal solution in terms of electricity bill minimization, in the case where the battery has infinite capacity with stable energy level. Simulation results show that even under reasonable battery size, a significant electricity cost reduction is achieved with the proposed policy.\",\n \"Title: Simulated Annealing for Optimal Resource Allocation in Wireless Networks with ImperfectCommunications.\\nYear: 2018\\n\\nAbstract: Simulated annealing (SA) method has had significant recent success in designing distributed control algorithms for wireless networks. These SA based techniques formed the basis of new CSMA algorithms and gave rise to the development of numerous variants to achieve the best system performance accommodating different communication technologies and more realistic system conditions. However, these algorithms do not readily extend to networks with noisy environments, as unreliable communication prevents them from gathering the necessary system state information needed to execute the algorithm. In recognition of this challenge, we propose a new SA algorithm that is designed to work more robustly in networks with communications that experience frequent message drops. The main idea of the proposed algorithm is a novel coupling technique that takes into account the external randomness of message passing failure events as a part of probabilistic uncertainty inherent in stochastic acceptance criterion of SA. As a result, the algorithm can be executed even with partial observation of system states, which was not possible under the traditional SA approach. We show that the newly proposed algorithm finds the optimal solution almost surely under the standard annealing framework while offering significant performance benefits in terms of its computational speed in the presence of frequent message drops.\",\n \"Title: Integrating Sub-6 GHz and Millimeter Wave to Combat Blockage: Delay-Optimal Scheduling.\\nYear: 2019\\n\\nAbstract: Millimeter wave (mmWave) technologies have the potential to achieve very high data rates, but suffer from intermittent connectivity. In this paper, we provision an architecture to integrate sub-6 GHz and mmWave technologies, where we incorporate the sub-6 GHz interface as a fallback data transfer mechanism to combat blockage and intermittent connectivity of the mmWave communications. To this end, we investigate the problem of scheduling data packets across the mmWave and sub-6 GHz interfaces such that the average delay of system is minimized. This problem can be formulated as Markov Decision Process. We first investigate the problem of discounted delay minimization, and prove that the optimal policy is of the threshold-type, i.e., data packets should always be routed to the mmWave interface as long as the number of packets in the system is smaller than a threshold. Then, we show that the results of the discounted delay problem hold for the average delay problem as well. Through numerical results, we demonstrate that under heavy traffic, integrating sub-6 GHz with mmWave can reduce the average delay by up to 70%. Further, our scheduling policy substantially reduces the delay over the celebrated MaxWeight policy.\",\n \"Title: Age-optimal Sampling and Transmission Scheduling in Multi-Source Systems.\\nYear: 2018\\n\\nAbstract: In this paper, we consider the problem of minimizing the age of information in a multi-source system, where samples are taken from multiple sources and sent to a destination via a channel with random delay. Due to interference, only one source can be scheduled at a time. We consider the problem of finding a decision policy that determines the sampling times and transmission order of the sources for minimizing the total average peak age (TaPA) and the total average age (TaA) of the sources. Our investigation of this problem results in an important separation principle: The optimal scheduling strategy and the optimal sampling strategy are independent of each other. In particular, we prove that, for any given sampling strategy, the Maximum Age First (MAF) scheduling strategy provides the best age performance among all scheduling strategies. This transforms our overall optimization problem into an optimal sampling problem, given that the decision policy follows the MAF scheduling strategy. While the zero-wait sampling strategy (in which a sample is generated once the channel becomes idle) is shown to be optimal for minimizing the TaPA, it does not always minimize the TaA. We use Dynamic Programming (DP) to investigate the optimal sampling problem for minimizing the TaA. Finally, we provide an approximate analysis of Bellman's equation to approximate the TaA-optimal sampling strategy by a water-filling solution which is shown to be very close to optimal through numerical evaluations.\",\n \"Title: Simulated Annealing for Optimal Resource Allocation in Wireless Networks with Imperfect Communications.\\nYear: 2018\\n\\nAbstract: Simulated annealing (SA) method has had significant recent success in designing distributed control algorithms for wireless networks. These SA based techniques formed the basis of new CSMA algorithms and gave rise to the development of numerous variants to achieve the best system performance accommodating different communication technologies and more realistic system conditions. However, these algorithms do not readily extend to networks with noisy environments, as unreliable communication prevents them from gathering the necessary system state information needed to execute the algorithm. In recognition of this challenge, we propose a new SA algorithm that is designed to work more robustly in networks with communications that experience frequent message drops. The main idea of the proposed algorithm is a novel coupling technique that takes into account the external randomness of message passing failure events as a part of probabilistic uncertainty inherent in stochastic acceptance criterion of SA. As a result, the algorithm can be executed even with partial observation of system states, which was not possible under the traditional SA approach. We show that the newly proposed algorithm finds the optimal solution almost surely under the standard annealing framework while offering significant performance benefits in terms of its computational speed in the presence of frequent message drops.\",\n \"Title: Towards achieving the maximum capacity in large mobile wireless networks under delay constraints.\\nYear: 2004\\n\\nAbstract: In this paper, we study how to achieve the maximum ca- pacity under delay constraints for large mobile wireless networks. We develop a systematic methodology for studying this problem in the asymptotic region when the number of nodes n in the network is large. We first identify a number of key parameters for a large class of scheduling schemes, and investigate the inherent tradeoffs among the capacity, the delay, and these scheduling parameters. Based on these inherent tradeoffs, we are able to compute the up- per bound on the maximum per-node capacity of a large mobile wireless network under given delay constraints. Further, in the process of proving the upper bound, we are able to identify the op- timal values of the key scheduling parameters. Knowing these op- timal values, we can then develop scheduling schemes that achieve the upper bound up to some logarithmic factor, which suggests that our upper bound is fairly tight. We have applied this methodology to both the i.i.d. mobility model and the random way-point mobil- ity model. In both cases, our methodology allows us to develop new scheduling schemes that can achieve larger capacity than previous proposals under the same delay constraints. In particular, for the i.i.d. mobility model, our scheme can achieve ( n 1=3=log3=2 n) per-node capacity with constant delay. This demonstrates that, un- der the i.i.d. mobility model, mobility increases the capacity even with constant delays. Our methodology can also be extended to incorporate additional scheduling constraints.\",\n \"Title: Optimal Energy-Aware Epidemic Routing in DTNs\\nYear: 2015\\n\\nAbstract: In this work, we investigate the use of epidemic routing in energy constrained delay tolerant networks (DTNs). In epidemic routing, messages are relayed by intermediate nodes at contact opportunities, i.e., when pairs of nodes come within the transmission range of each other. Each node needs to decide whether to forward its message upon contact with a new node based on its own residual energy level and the age of that message. We mathematically characterize the fundamental trade-off between energy conservation and a measure of Quality of Service as a dynamic energy-dependent optimal control problem. We prove that in the mean-field regime, the optimal dynamic forwarding decisions follow simple threshold-based structures in which the forwarding threshold for each node depends on its current remaining energy. We then characterize the nature of this dependence. Our simulations reveal that the optimal dynamic policy significantly outperforms heuristics.\",\n \"Title: A New Alternating Direction Method for Linear Programming.\\nYear: 2017\\n\\nAbstract: It is well known that, for a linear program (LP) with constraint matrix A is an element of R-mxn, the Alternating Direction Method of Multiplier converges globally and linearly at a rate O((parallel to A parallel to(2)(F) + mn) log(1/epsilon)). However, such a rate is related to the problem dimension and the algorithm exhibits a slow and fluctuating \\\"tail convergence\\\" in practice. In this paper, we propose a new variable splitting method of LP and prove that our method has a convergence rate of O(parallel to A parallel to(2) log(1/epsilon)). The proof is based on simultaneously estimating the distance from a pair of primal dual iterates to the optimal primal and dual solution set by certain residuals. In practice, we result in a new first-order LP solver that can exploit both the sparsity and the specific structure of matrix A and a significant speedup for important problems such as basis pursuit, inverse covariance matrix estimation, L1 SVM and nonnegative matrix factorization problem compared with the current fastest LP solvers.\",\n \"Title: Flexible Load Balancing with Multi-dimensional State-space Collapse: Throughput and Heavy-traffic Delay Optimality.\\nYear: 2018\\n\\nAbstract: Heavy traffic delay analysis for load balancing policies has relied heavily on a condition called state-space collapse onto a single-dimensional line. In this paper, via Lyapunov driftbased method, we rigorously prove that even under a multidimensional state-space collapse, steady-state heavy-traffic delay optimality can still be achieved for a general load balancing system. This result directly implies that achieving steady-state heavy-traffic delay optimality simply requires that no server is kept idling while others are busy at heavy loads, thus complementing and extending the result obtained by diffusion approximations. Further, we explore the greater flexibility provided by allowing a multidimensional state-space collapse in designing new load balancing policies that are both throughput optimal and heavytraffic delay optimal in steady state.\",\n \"Title: A Faster FPTAS for Knapsack Problem With Cardinality Constraint.\\nYear: 2019\\n\\nAbstract: We study the $K$-item knapsack problem (ie, $1.5$-dimensional KP), which is a generalization of the famous 0-1 knapsack problem (ie, $1$-dimensional KP) in which an upper bound $K$ is imposed on the number of items selected. This problem is of fundamental importance and is known to have a broad range of applications in various fields such as computer science and operation research. It is well known that, there is no FPTAS for the $d$-dimensional knapsack problem when $dgeq 2$, unless P $=$ NP. While the $K$-item knapsack problem is known to admit an FPTAS, the complexity of all existing FPTASs have a high dependency on the cardinality bound $K$ and approximation error $varepsilon$, which could result in inefficiencies especially when $K$ and $varepsilon^{-1}$ increase. The current best results are due to cite{mastrolilli2006hybrid}, in which two schemes are presented exhibiting a space-time tradeoff--one scheme with time complexity $O(n+Kz^{2}/varepsilon^{2})$ and space complexity $O(n+z^{3}/varepsilon)$, while another scheme requires $O(n+(Kz^{2}+z^{4})/varepsilon^{2})$ run-time but only needs $O(n+z^{2}/varepsilon)$ space, where $z=min{K,1/varepsilon}$. In this paper we close the space-time tradeoff exhibited in cite{mastrolilli2006hybrid} by designing a new FPTAS with a run-time of $widetilde{O}(n+z^{2}/varepsilon^{2})$, while simultaneously reaching the $O(n+z^{2}/varepsilon)$ space bound. Our scheme provides $widetilde{O}(K)$ and $O(z)$ improvements on the long-established state-of-the-art algorithms in time and space complexity respectively, and is the first scheme that achieves a run-time that is asymptotically independent of cardinality bound $K$ under fixed $varepsilon$. Another salient feature of our scheme is that it is the first FPTAS, which achieves better time and space complexity bounds than the very first standard FPTAS over all parameter regimes.\",\n \"Title: Joint Antenna Allocation and Link Scheduling in FlexRadio Networks\\nYear: 2019\\n\\nAbstract: FlexRadio, a recent breakthrough in wireless Multi-RF technology, has introduced a new way to unify MIMO and full-duplex into a single framework with a fully flexible design. FlexRadio allows a wireless node to use an arbitrary number of RF chains to support transmission and reception, which makes MIMO and full-duplex subset configurations of FlexRadio. This new architecture has greatly changed the feasibility constraint in wireless networks, which makes the design of high performance MAC layer algorithms even more challenging. First, the RF chain becomes a new resource that needs to be allocated across the network, and the optimal configuration depends not only on the network topology and flow demand, but also on the number of available RF chains at each node. Second, it is not clear how to jointly allocate links and RF chain resources based on the arrival rates and queueing dynamics. In this paper, we introduce a new virtual link model to characterize the feasibility constraint from the perspective of contending RF chain usage. Based on this novel model, a distributed CSMA-like framework is developed to fully leverage the flexibility of RF chain resource allocation.\",\n \"Title: Data Poisoning Attacks on Stochastic Bandits.\\nYear: 2019\\n\\nAbstract: Stochastic multi-armed bandits form a class of online learning problems that have important applications in online recommendation systems, adaptive medical treatment, and many others. Even though potential attacks against these learning algorithms may hijack their behavior, causing catastrophic loss in real-world applications, little is known about adversarial attacks on bandit algorithms. In this paper, we propose a framework of offline attacks on bandit algorithms and study convex optimization based attacks on several popular bandit algorithms. We show that the attacker can force the bandit algorithm to pull a target arm with high probability by a slight manipulation of the rewards in the data. Then we study a form of online attacks on bandit algorithms and propose an adaptive attack strategy against any bandit algorithm without the knowledge of the bandit algorithm. Our adaptive attack strategy can hijack the behavior of the bandit algorithm to suffer a linear regret with only a logarithmic cost to the attacker. Our results demonstrate a significant security threat to stochastic bandits.\",\n \"Title: ERSCC: Enable Efficient and Reliable Screen-Camera Communication\\nYear: 2019\\n\\nAbstract: Each camera on digital devices is made of hundreds of thousands of sensors, with which it can separate and capture the light from spatial points in a fine-grain manner, enabling high-rate data transfer from the digital display to the camera, i.e. screen-camera communication. Compared with RF (Radio Frequency) technologies, visible light approaches are more convenient and secure.\\n\\nIn this work, we design a mobile-to-mobile screen-camera communication system to handle the rolling shutter issue and increase the reliability. First, a time-domain self-restoration coding scheme is proposed to identify mixed frames for doubling the coding efficiency. Second, we design a feedback channel for reliability. It is further integrated with an adaptive scheme to achieve robustness in challenging conditions. We implement the system prototype on the Android platform and conduct extensive experiments. The results show that our system increases the throughput by an order-of-magnitude (16x) compared with existing rolling-shutter solutions and two times (1.8x) over the color-barcode system.\",\n \"Title: Battle between Rate and Error in Minimizing Age of Information\\nYear: 2021\\n\\nAbstract: ABSTRACTIn this paper, we consider a status update system, in which update packets are sent to the destination via a wireless medium that allows for multiple rates, where a higher rate also naturally corresponds to a higher error probability. The data freshness is measured using age of information, which is defined as the age of the recent update at the destination. A packet that is transmitted with a higher rate, will encounter a shorter delay and a higher error probability. Thus, the choice of the transmission rate affects the age at the destination. In this paper, we design a low-complexity scheduler that selects between two different transmission rate and error probability pairs to be used at each transmission epoch. This problem can be cast as a Markov Decision Process. We show that there exists a threshold-type policy that is age-optimal. More importantly, we show that the objective function is quasi-convex or non-decreasing in the threshold, based on the system parameters values. This enables us to devise a low-complexity algorithm to minimize the age. These results reveal an interesting phenomenon: While choosing the rate with minimum mean delay is delay-optimal, this does not necessarily minimize the age.\",\n \"Title: Can Online Learning Increase the Reliability of Extreme Mobility Management?\\nYear: 2021\\n\\nAbstract: Seamless Internet access under extreme user mobility is highly demanded on high-speed trains and vehicles. However, existing mobile networks (e.g., 4G LTE and 5G NR) cannot reliably satisfy this demand, with a 5.5%-12.6% handover failure ratio at 200–350 km/h. A root cause is that, the 4G/5G handovers have to balance the exploration of more measurements for satisfactory handover and the exploitati...\",\n \"Title: Age-Optimal Low-Power Status Update Over Time-Correlated Fading Channel\\nYear: 2021\\n\\nAbstract: In this paper, we consider transmission scheduling in a status update system, where updates are generated periodically and transmitted over a Gilbert-Elliott fading channel. The goal is to minimize the long-run average age of information (AoI) at the destination under an average energy constraint. The channel state is revealed by the feedback (Ack/Nack) of a transmission; while it remains unknown if there is no transmission. Thus, we have to design a scheduling policy that balances tradeoffs across energy, AoI, channel exploration, and channel exploitation. The problem is formulated as a constrained partially observable Markov decision process problem (POMDP). We show that the optimal policy is a randomized mixture of no more than two stationary deterministic policies each of which is of a threshold-type in the belief on the channel. We propose a finite-state approximation for our infinite-state belief MDP and show convergence. Based on the theoretical insights gained from studying this problem, we develop an optimal algorithm using the structure of the problem.\",\n \"Title: Remote Tracking of Distributed Dynamic Sources over A Random Access Channel with One-bit Updates\\nYear: 2021\\n\\nAbstract: In this work, we consider a network, where n distributed information sources whose states evolve according to a random process transmit their time-varying states to a remote estimator over a shared wireless channel. Each source generates packets in a decentralized manner and employs a slotted random access mechanism to transmit the packets. In particular, we are interested in networks with a large...\",\n \"Title: Optimizing Sampling for Data Freshness: Unreliable Transmissions with Random Two-way Delay\\nYear: 2022\\n\\nAbstract: In this paper, we study a sampling problem, in which freshly sampled data is sent to a remote destination via an unreliable channel, and acknowledgments are sent back on a feedback channel. Both the forward and feedback channels are subject to random transmission times. We optimize the sampling strategy at the source (e.g., a sensor), aiming to enhance the freshness of data samples delivered to the destination (e.g., an estimator). This sampling problem is motivated by a distributed sensing system, where an estimator estimates a signal by combining noisy signal observations collected from a local sensor and accurate signal samples received from a remote sensor. We show that the optimal estimation error is an increasing function of the age of received signal samples. The optimal sampling problem for general non-decreasing age functions is formulated as an MDP with an uncountable state space. An exact solution to this problem is derived, which has a simple threshold-type structure. The threshold can be calculated by low-complexity bisection search and fixed-point iterations. We find that, after a successful packet delivery, the optimal sampler may wait before taking the next sample and sending it out, whereas no waiting time should be added if the previous transmission failed.\",\n \"Title: Interference Constrained Beam Alignment for Time-Varying Channels via Kernelized Bandits\\nYear: 2022\\n\\nAbstract: To fully utilize the abundant spectrum resources in millimeter wave (mmWave), Beam Alignment (BA) is necessary for large antenna arrays to achieve large array gains. In practical dynamic wireless environments, channel modeling is challenging due to time-varying and multipath effects. In this paper, we formulate the beam alignment problem as a nonstationary online learning problem with the objective to maximize the received signal strength under interference constraint. In particular, we employ the non-stationary kernelized bandit to leverage the correlation among beams and model the complex beamforming and multipath channel functions. Furthermore, to mitigate interference to other user equipment, we leverage the primal-dual method to design a constrained UCB-type kernelized bandit algorithm. Our theoretical analysis indicates that the proposed algorithm can adaptively adjust the beam in time-varying environments, such that both the cumulative regret of the received signal and constraint violations have sublinear bounds with respect to time. This result is of independent interest for applications such as adaptive pricing and news ranking. In addition, the algorithm assumes the channel is a black-box function and does not require any prior knowledge for dynamic channel modeling, and thus is applicable in a variety of scenarios. We further show that if the information about the channel variation is known, the algorithm will have better theoretical guarantees and performance. Finally, we conduct simulations to highlight the effectiveness of the proposed algorithm.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":41,"string":"41"}}},{"rowIdx":42,"cells":{"question_id":{"kind":"string","value":"Helmut Seidl"},"question":{"kind":"string","value":"Generate an abstract for the title \"Fast and simple nested fixpoints\" using the following items: - Alternative proof\n- Nested fixpoint expressions\n- Complete lattice\n- Time complexity\n- Modal ?￥--calculus"},"answer":{"kind":"string","value":"We give an alternative proof of the result ofLong et al. in [11] that nested fixpoint expressions e of alternation depth d ? 0 can be evaluatedover a complete lattice of height h in timeO((h \\Delta jej)d=2+2). The advantage of our proof isthat it is both extremely short and extremelysimple.1 IntroductionSince Kozen's seminal paper [10] on modal ?￥--calculus in 1983, this logic has been widelyused for the specification of properties of concurrentprocesses (see, e.g., [12, 13])...."},"correct_answer":{"kind":"string","value":"We give an alternative proof of the result ofLong et al. in [11] that nested fixpoint expressions e of alternation depth d ? 0 can be evaluatedover a complete lattice of height h in timeO((h \\Delta jej)d=2+2). The advantage of our proof isthat it is both extremely short and extremelysimple.1 IntroductionSince Kozen's seminal paper [10] on modal ?￥--calculus in 1983, this logic has been widelyused for the specification of properties of concurrentprocesses (see, e.g., [12, 13])...."},"documents":{"kind":"list like","value":["Title: Binary Queries\nYear: 2002\n\nAbstract: Querying XML documents is a basic task for many XML applications. Typically, matches of queries are located individually, i.e. a match is a single node in a queried document. k-ary queries, in contrast, simultaneously identify k locations in the document, which are connected via some specified relation. For example, in rule-based transformations (like XSLT transformations), a node to which a rule is applied and another node which is selected by the rule in the context of the first node could be identified together by a binary query defining the relation between these two nodes. Such a binary query would replace the match and the select pattern used to identify the first and the second node respectively. By eliminating the need for select patterns, binary queries would not only reduce the number of patterns in a transformation, but would also allow that all the pattern matching is done statically, i.e. before the transformation actually begins. We use the formalism of regular forest grammars to define queries of arbitrary arities. Pushdown forest automata have been used in the past to efficiently implement unary queries expressed by using forest grammars. The main contribution of this paper is an algorithm based on pushdown forest automata which evaluates binary queries. In the worst theoretical case the algorithm evaluates binary queries in time proportional to the square of the size of the input document. In practice however, the complexity is mostly rather linear in the input size. Queries for which the right context does not need to be checked can be evaluated even along with the parsing of the input document. Rather than using forest grammars, queries can be also expressed in a more intuitive pattern language using a syntax similar to XPath.","Title: Transparent teleteaching\nYear: 2002\n\nAbstract: Today's teleteaching software restricts teaching in the way that it only supports a specific presentation application and a single platform. This is a major drawback and a reason why teleteaching is not that widespread as it could be. Therefore we have created a teleteaching environment, called TeleTeachingTool, which enables lecture recording and transmission to be done transparently to teaching. Our tool allows teachers to use arbitrary software including their preferred presentation tool running on their favorite platform. It combines desktop recording with real-time audio and video streams to a recordable and online presentable lecture. In this paper we will discuss the requirements of teleteaching, describe our teleteaching environment and compare it with other teaching software.","Title: Annotiertes Lecture Recording\nYear: 2004\n\nAbstract: Zur Durchführung virtueller Vorlesungen ist es nützlich, neben Ton und Bild auch jeweils den gesamten Desktop aufzuzeichnen und zu übertragen. Dies wird durch die Benutzung von anwendungsunabhängigem Screen-Recording unterstützt. Ebenfalls für Präsentationen bewährt haben sich Annotations- möglichkeiten, die es gestatten, die Aufmerksamkeit zu fokussieren und Vermerke auf einer ansonsten überwiegend statischen Projektionfläche anzubringen. Wir berichten über eine erfolgreiche Kombination von allgemeinem Screen-Recording mit einem einfachen aber flexiblen Annotierungssystem für den gesamten Desktop und zeigen, dass dies die Dynamik der Vorlesungen erhöht.","Title: Automatic Complexity Analysis\nYear: 2002\n\nAbstract: We consider the problem of automating the derivation of tight asymptotic complexity bounds for solving Horn clauses. Clearly, the solving time crucially depends on the "sparseness" of the computed relations. Therefore, our asymptotic runtime analysis is accompanied by an asymptotic sparsity calculus together with an asymptotic sparsity analysis. The technical problem here is that least fixpoint iteration fails on asymptotic complexity expressions: the intuitive reason is that O(1)+ O(1) = O(1)...","Title: Interprocedural herbrand equalities\nYear: 2005\n\nAbstract: We present an aggressive interprocedural analysis for inferring value equalities which are independent of the concrete interpretation of the operator symbols. These equalities, called Herbrand equalities, are therefore an ideal basis for truly machine-independent optimizations as they hold on every machine. Besides a general correctness theorem, covering arbitrary call-by-value parameters and local and global variables, we also obtain two new completeness results: one by constraining the analysis problem to Herbrand constants, and one by allowing side-effect-free functions only. Thus if we miss a constant/equality in these two scenarios, then there exists a separating interpretation of the operator symbols.","Title: Numerical document queries\nYear: 2003\n\nAbstract: A query against a database behind a site like Napster may search, e.g., for all users who have downloaded more jazz titles than pop music titles. In order to express such queries, we extend classical monadic second-order logic by Presburger predicates which pose numerical restrictions on the children (content) of an element node and provide a precise automata-theoretic characterization. While the existential fragment of the resulting logic is decidable, it turns out that satisfiability of the full logic is undecidable. Decidable satisfiability and a querying algorithm even with linear data complexity can be obtained if numerical constraints are only applied to those contents of elements where ordering is irrelevant. Finally, it is sketched how these techniques can be extended also to answer questions like, e.g., whether the total price of the jazz music downloaded so far exceeds a user's budget.","Title: Macro forest transducers\nYear: 2004\n\nAbstract: XML documents conceptually are not trees, but forests. Therefore, we extend the concept of macro tree transducers (mtt's) to a transformation formalism of forests, macro forest transducers (mft's). We show that mft's form a strict superset of mtt's operating on forests (represented as binary trees). On the other hand, the transformation of every mft can be simulated by the composition of two mtt's. Although macro forest transducers are more powerful, the complexity of inverse type inference, i.e., computing the pre-image of a recognizable language, is almost the same as for tree transducers.","Title: On the Finite Degree of Ambiguity of Finite Tree Automata\nYear: 1989\n\nAbstract: The degree of ambiguity of a finite tree automaton A, da(A), is the maximal number of different accepting computations of A for any possible input tree. We show: it can be decided in polynomial time whether or not da(A)A with n states and rank L>1 having a finite degree of ambiguity: for every input tree t there is a input tree t1 of depth less than 22n·n! having the same number of accepting computations; the degree of ambiguity of A is bounded by 222·log(L+1)·n.","Title: A Note on Karr's Algorithm\nYear: 2004\n\nAbstract: We give a simple formulation of Karr's algorithm for computing all affine relationships in affine programs. This simplified algorithm runs in time O(nk(3)) where n is the program size and k is the number of program variables assuming unit cost for arithmetic operations. This improves upon the original formulation by a factor of k. Moreover, our re-formulation avoids exponential growth of the lengths of intermediately occurring numbers (in binary representation) and uses less complicated elementary operations. We also describe a generalization that determines all polynomial relations up to degree d in time O(nk(3d)).","Title: Computing polynomial program invariants\nYear: 2004\n\nAbstract: We present two automatic program analyses. The first analysis checks if a given polynomial relation holds among the program variables whenever control reaches a given program point. It fully interprets assignment statements with polynomial expressions on the right-hand side and polynomial disequality guards. Other assignments are treated as non-deterministically assigning any value and guards that are not polynomial disequalities are ignored. The second analysis extends this checking procedure. It computes the set of all polynomial relations of an arbitrary given form that are valid at a given target program point. It is also complete up to the abstraction described above.","Title: Analysis of modular arithmetic\nYear: 2007\n\nAbstract: We consider integer arithmetic modulo a power of 2 as providedby mainstream programming languages like Java or standardimplementations of C. The difficulty here is that, for w 1, the ring Zm of integers modulom = 2w has zero divisors and thus cannotbe embedded into a field. Not withstanding that, we present intra-and interprocedural algorithms for inferring for every programpoint u affine relations between program variables valid atu. If conditional branching is replaced withnondeterministic branching, our algorithms are not only sound butalso complete in that they detect all valid affinerelations in a natural class of programs. Moreover, they run intime linear in the program size and polynomial in the number ofprogram variables and can be implemented by using the same modularinteger arithmetic as the target language to be analyzed. We alsoindicate how our analysis can be extended to deal with equalityguards, even in an interprocedural setting.","Title: Interprocedural analyses: a comparison\nYear: 2000\n\nAbstract: We present a framework for program analysis of languages with procedures which is general enough to allow for a comparison of various approaches to interprocedural analysis. Our framework is based on a small-step operational semantics and subsumes both frameworks for imperative and for logic languages. We consider reachability analysis, that is, the problem of approximating the sets of program states reaching program points. We use our framework in order to clarify the impact of several independent design decisions on the precision of the analysis. Thus, we compare intraprocedural forward accumulation with intraprocedural backward accumulation. Furthermore, we consider both relational and functional approaches. While for relational analysis the accumulation strategy makes no difference in precision, we prove for functional analysis that forward accumulation may lose precision against backward accumulation. Concerning the relative precision of relational analyses and corresponding functional analyses, we exhibit scenarios where functional analysis does not lose precision. Finally, we explain why even an enhancement of functional analysis through disjunctive completion of the underlying abstract domain may sometimes lose precision against relational analysis.","Title: Games through Nested Fixpoints\nYear: 2009\n\nAbstract: In this paper we consider two-player zero-sum payoff games on finite graphs, both in the deterministic as well as in the stochastic setting. In the deterministic setting, we consider total-payoff games which have been introduced as a refinement of mean-payoff games [10, 18]. In the stochastic setting, our class is a turn-based variant of liminf-payoff games [4, 15, 16]. In both settings, we provide a non-trivial characterization of the values through nested fixpoint equations. The characterization of the values of liminf-payoff games moreover shows that solving liminf-payoff games is polynomial-time reducible to solving stochastic parity games. We construct practical algorithms for solving the occurring nested fixpoint equations based on strategy iteration. As a corollary we obtain that solving deterministic total-payoff games and solving stochastic liminf-payoff games is in UP *** co*** UP.","Title: Polynomial Constants Are Decidable\nYear: 2002\n\nAbstract: Constant propagation aims at identifying expressions that always yield a unique constant value at run-time. It is well-known that constant propagation is undecidable for programs working on integers even if guards are ignored as in non-deterministic flow graphs. We show that polynomial constants are decidable in non-deterministic flow graphs. In polynomial constant propagation, assignment statements that use the operators +, ,� are interpreted exactly but all assignments that use other operators are conservatively interpreted as non-deterministic as- signments. We present a generic algorithm for constant propagation via a symbolic weakest precondition computation and show how this generic algorithm can be instantiated for polynomial constant propagation by exploiting techniques from computable ring theory.","Title: Infinite-State High-Level MSCs: Model-Checking and Realizability\nYear: 2002\n\nAbstract: We consider three natural classes of infinite-state HMSCs: globally-cooperative, locally-cooperative and local-choice HMSCs. We show first that model-checking for globally-cooperative and locally-cooperative HMSCs has the same complexity as for the class of finite-state (bounded) HMSCs. Surprisingly, model-checking local-choice HMSCs turns out to be exponentially more efficient in space than for locally-cooperative HMSCs. We also show that locally-cooperative and local-choice HMSCs can be always implemented by communicating finite states machines, provided we allow some additional (bounded) message data. Moreover, the implementation of local-choice HMSCs is deadlock-free and of linear-size.","Title: Locating Matches of Tree Patterns in Forests\nYear: 1998\n\nAbstract: s and 1/TechReports/FullTextVia WWW: URL <a href=\"http://citeseer.ist.psu.edu/rd/0/http%3AqSqqSqwww.informatik.uni-trier.deqSqReportsqSqList\" onmouseover=\"self.status=\"http://www.informatik.uni-trier.de/Reports/List\"; return true\" onmouseout=\"self.status=\"\"; return true\">http://www.informatik.uni-trier.de/Reports/List</a>Via email: Send a mail to ftpmail@ftp.informatik.uni-trier.de, subject'MAIL ME CLEAR\", body \"TechReports.HowTo\" followedby an empty line, for detailed instructionsPrinted copies:Trierer ForschungsberichteFachbereich IV -Mathematik / InformatikUniversitat Trier..D-54286 TrierISSN 0944-0488Forschungsbericht Nr. 98--08Locating Matches of Tree Patterns in ForestsAndreas Neumann and Helmut...","Title: Parameter-reduction of higher level grammars\nYear: 1987\n\nAbstract: A higher level (OI-) grammar is called terminating if for every accessible term t there is at least one terminal term which can be derived from t . A grammar is called parameter-reduced if it is terminating and has no superfluous parameters. For every grammar G of level n 0 which generates at least one term we construct grammars R( G ) and P( G ) such that R( G ) and P( G ) generate the same language as G but are terminating and parameter-reduced respectively. We introduce a hierarchy of restrictions to the delection capability of the grammars which allow a gradual decrease in the complexity of the algorithms from n -iterated exponential time to polynomial time.","Title: Precise relational invariants through strategy iteration\nYear: 2007\n\nAbstract: We present a practical algorithm for computing exact least solutions of systems of equations over the rationals with addition, multiplication with positive constants, minimum and maximum. The algorithm is based on strategy improvement combined with solving linear programming problems for each selected strategy. We apply our technique to compute the abstract least fixpoint semantics of affine programs over the relational template constraint matrix domain [20]. In particular, we thus obtain practical algorithms for computing the abstract least fixpoint semantics over the zone and octagon abstract domain.","Title: The Fork95 parallel programming language: design, implementation, application\nYear: 1997\n\nAbstract: Fork95 is an imperative parallel programming language intended to express algorithms for synchronous shared memory machines\n (PRAMs). It is based on ANSI C and offers additional constructs to hierarchically divide processor groups into subgroups and\n manage shared and private address subspaces. Fork95 makes the assembly-level synchronicity of the underlying hardware available\n to the programmer at the language level. Nevertheless, it supports locally asynchronous computation where desired by the programmer.\n We present a one pass compiler, fcc, which compiles Fork95 and C programs to the SB-PRAM machine. The SB-PRAM is a lock-step\n synchronous, massively parallel multiprocessor currently being built at Saarbrücken University, with a physically shared memory\n and uniform memory access time. We examine three important types of parallel computation frequently used for the parallel\n solution of real-world problems. While farming and parallel divide-and-conquer are directly supported by Fork95 language constructs,\n pipelining can be easily expressed using existing language features; an additional language construct for pipelining is not\n required.","Title: ForkLight: A Control-Synchronous Parallel Programming Language\nYear: 1999\n\nAbstract: ForkLight is an imperative, task-parallel programming language for massively parallel shared memory machines. It is based on ANSI C, follows the SPMD model of parallel program execution, provides a sequentially consistent shared memory, and supports dynamically nested parallelism. While no assumptions are made on uniformity of memory access time or instruction- level synchronicity of the underlying hardware, ForkLight offers a simple but powerful mecha- nism for coordination of parallel processes in the traditio n and notation of PRAM algorithms: Be- yond its asynchronous default execution mode, ForkLight offers a mode for control-synchronous execution that relates the program's block structure to par allel control flow. We give a scheme for compiling ForkLight to C with calls to a very small set of basic shared memory access operations like atomic fetch&add. This yields portability across parallel archi- tectures and exploits the local optimizations of their nati ve C compilers. Our implementation is publically available; performance results are reported. We also discuss translation to OpenMP. 1. INTRODUCTION. Parallel processing offers an attractive way to increase com- puter performance. MIMD architectures, where program control is individual to each processor, offer high flexibility in programming, but devising, implementing and debug- ging parallel programs is difficult. Even more difficulties arise if the programmer has to care about explicit data distribution to achieve reasonable performan ce. Automatic parallelization and automatic data distribution techniques are still lim ited to rather reg- ular programs. Addressing the latter problem, parallel computer manufactu rers and re- search groups recently devised several types of massively parallel (or at least s calable) machines providing a shared memory. Some of these still require program tuning for locality to perform efficiently, e.g. Stanford DASH (18), while others use multithread- ing to hide the memory access latency and high-bandwidth memory networks, and thus become more or less independent of locality issues, e.g. Tera MTA (2). So far there is only one massively parallel shared memory architecture that of fers uniform memory access time (UMA), the SB-PRAM (1). Due to a common clockall processors of the SB-PRAM work synchronously, i.e. they start (and complete) exe- cution of an instruction simultaneously. This synchronicity makes par allel program- ming very easy, as it leads to deterministic parallel program execution; it i s particularly well suited for the implementation of synchronous algorithms using e.g. fine-grained pipelines or data-parallel operations. Furthermore, such synchronous MI MD machines with UMA shared memory are very popular in theoretical computer science, where they are known as PRAMs (Parallel Random Access Machines). On the other hand, no massively parallel MIMD machine that is commercially avail- able today is UMA or synchronous in this sense. Rather, the following features are common: The user sees a large amount of threads (due to scalable architecture and multithreading) and a monolithic shared memory (due to a hidden network). There is no common clock. The memory access time is non-uniform, but more or less indepen- dent of locality (due to multithreading). Program execution is asynchro nous (due to the","Title: Single-valuedness of tree transducers is decidable in polynomial time\nYear: 1992\n\nAbstract: A bottom-up finite-state tree transducer (FST) A is called single-valued iff for every input tree there is at most one output tree. We give a polynomial-time algorithm which decides whether or not a given FST is single-valued. The algorithm is based on: • the freedom of the submonoid of trees which contain at least one occurrence of one variable ∗; • the succinct representation of trees by graphs; • a sequence of normalizing transformations of the given transducer; and • a polynomially decidable characterization of pairs of equivalent output functions. We apply these methods to show that finite-valuedness is decidable in polynomial time as well.","Title: Contextual Locking for Dynamic Pushdown Networks.\nYear: 2013\n\nAbstract: Contextual locking is a scheme for synchronizing between possibly recursive processes that has been proposed by Chadha et al. recently. Contextual locking allows for arbitrary usage of locks within the same procedure call and Chadha et al. show that control-point reachability for two processes adhering to contextual locking is decidable in polynomial time. Here, we complement these results. We show that in presence of contextual locking, control-point reachability becomes PSPACE-hard, already if the number of processes is increased to three. On the other hand, we show that PSPACE is both necessary and sufficient for deciding control-point reachability of k processes for k > 2, and that this upper bound remains valid even if dynamic spawning of new processes is allowed. Furthermore, we consider the problem of regular reachability, i.e., whether a configuration within a given regular set can be reached. Here, we show that this problem is decidable for recursive processes with dynamic thread creation and contextual locking. Finally, we generalize this result to processes that additionally use a form of join operations.","Title: Precise Interval Analysis vs. Parity Games\nYear: 2008\n\nAbstract: In [8], a practical algorithm for precise interval analysis is provided for which, however, no non-trivial upper complexity bound is known. Here, we present a lower bound by showing that precise interval analysis is at least as hard as computing the sets of winning positions in parity games. Our lower-bound proof relies on an encoding of parity games into systems of particular integer equations. Moreover, we present a simplification of the algorithm for integer systems from [8]. For the given encoding of parity games, the new algorithm provides another algorithm for parity games which is almost as efficient as the discrete strategy improvement algorithm by Vöge and Jurdziński [17].","Title: Flat and one-variable clauses: Complexity of verifying cryptographic protocols with single blind copying\nYear: 2008\n\nAbstract: Cryptographic protocols with single blind copying were defined and modeled by Comon and Cortier using the new class C of first-order clauses. They showed its satisfiability problem to be in 3-DEXPTIME. We improve this result by showing that satisfiability for this class is NEXPTIME-complete, using new resolution techniques. We show satisfiability to be DEXPTIME-complete if clauses are Horn, which is what is required for modeling cryptographic protocols. While translation to Horn clauses only gives a DEXPTIME upper bound for the secrecy problem for these protocols, we further show that this secrecy problem is actually DEXPTIME-complete.","Title: Least and greatest solutions of equations over N\nYear: 1996\n\nAbstract: We consider the problem of computing least and greatest solutions of a system of equations xi = fi, i = 1,..., n, over N, i.e., the naturals (extended by ∞), where the right hand sides fi are expressions built up from constants and variables by various sets of operations.We present efficient algorithms in case where the following operations occur: (1) minimum and maximum; (2) maximum, addition and multiplication; (3) minimum, addition and multiplication; (4) minimum, maximum, addition and multiplication. We extend the methods to the cases where (one-sided) conditionals are allowed as well.","Title: Side-effect analysis of assembly code\nYear: 2011\n\nAbstract: In this paper we present a light-weight interprocedural side-effect analysis on assembly code. We represent the modifying potential of a procedure f by classifying all write accesses, occurring within f, relative to the parameter registers. In particular our approach is the first to accurately handle reference parameters. We demonstrate the usefulness of this approach by integrating this analysis into our assembly analyser and provide an evaluation of the precision of our approach. Approximately 50 per cent of all procedures can be statically shown to have side-effects.","Title: Interprocedural Information Flow Analysis of XML Processors.\nYear: 2014\n\nAbstract: A crucial issue when providing publicly accessible web services is that sensitive data should only be accessible by authorized users. Accessibility of data within an application or information flow can conveniently be formalized as a 2-hyperproperty of a program. Here, we present a technique to interprocedurally analyze information flow in XML processors. Our approach is based on general techniques for program matching, and relational abstract interpretation of the resulting 2-programs. In case of XML processors, the abstract relational semantics then can be practically analyzed by means of finite tree automata.","Title: Verifying a local generic solver in coq\nYear: 2010\n\nAbstract: Fixpoint engines are the core components of program analysis tools and compilers. If these tools are to be trusted, special attention should be paid also to the correctness of such solvers. In this paper we consider the local generic fixpoint solver RLD which can be applied to constraint systems x ⊇ fx, x ∈ V, over some lattice D where the right-hand sides fx are given as arbitrary functions implemented in some specification language. The verification of this algorithm is challenging, because it uses higher-order functions and relies on side effects to track variable dependences as they are encountered dynamically during fixpoint iterations. Here, we present a correctness proof of this algorithm which has been formalized by means of the interactive proof assistant COQ.","Title: Control-Flow Analysis in Cubic Time\nYear: 2001\n\nAbstract: It is well-known that context-independent control flow analysis can be performed in cubic time for functional and object-oriented languages. Yet recent applications of control flow analysis to calculi of computation (like the π-calculus and the ambient calculus) have reported considerably higher complexities. In this paper we introduce two general techniques, the use of Horn clauses with sharing and the use of tiling of Horn clauses, for reducing the worst-case complexity of analyses. Applying these techniques to the π-calculus and the ambient calculus we reduce the complexity from O(n5) to O(n3) in both cases.","Title: Precise Analysis Of Value-Dependent Synchronization In Priority Scheduled Programs\nYear: 2014\n\nAbstract: Although priority scheduling in concurrent programs provides a clean way of synchronization, developers still additionally rely on hand-crafted schemes based on integer variables to protect critical sections. We identify a set of sufficient conditions for variables to serve this purpose. We provide efficient methods to verify these conditions, which enable us to construct an enhanced analysis of mutual exclusion in interrupt-driven concurrent programs. All our algorithms are build upon off-the-shelf inter-procedural analyses alone. We have implemented this approach for the analysis of automotive controllers, and demonstrate that it results in a major improvement in the precision of data race detection compared to purely priority-based techniques.","Title: Crossing the syntactic barrier: hom-disequalities for H1-clauses\nYear: 2012\n\nAbstract: We extend ${\\mathcal H}_1$-clauses with disequalities between images of terms under a tree homomorphism (hom-disequalities). This extension allows to test whether two terms are distinct modulo a semantic interpretation, allowing, e.g., to neglect information that is not considered relevant for the intended comparison. We prove that ${\\mathcal H}_1$-clauses with hom-disequalities are more expressive than ${\\mathcal H}_1$-clauses with ordinary term disequalities, and that they are incomparable with ${\\mathcal H}_1$-clauses with disequalities between paths. Our main result is that ${\\mathcal H}_1$-clauses with this new type of constraints can be normalized into an equivalent tree automaton with hom-disequalities. Since emptiness for that class of automata turns out to be decidable, we conclude that satisfiability is decidable for positive Boolean combinations of queries to predicates defined by ${\\mathcal H}_1$-clauses with hom-disequalities.","Title: Precise fixpoint computation through strategy iteration\nYear: 2007\n\nAbstract: We present a practical algorithm for computing least solutions of systems of equations over the integers with addition, multiplication with positive constants, maximum and minimum. The algorithm is based on strategy iteration. Its run-time (w.r.t. the uniform cost measure) is independent of the sizes of occurring numbers. We apply our technique to solve systems of interval equations. In particular, we show how arbitrary intersections as well as full interval multiplication in interval equations can be dealt with precisely.","Title: Minimization of deterministic bottom-up tree transducers\nYear: 2010\n\nAbstract: We show that for every deterministic bottom-up tree transducer, a unique equivalent transducer can be constructed which is minimal. The construction is based on a sequence of normalizing transformations which, among others, guarantee that non-trivial output is produced as early as possible. For a deterministic bottom-up transducer where every state produces either none or infinitely many outputs, the minimal transducer can be constructed in polynomial time.","Title: On finitely generated monoids of matrices with entries in N\nYear: 1991\n\nAbstract: Let GAMMA be a nonempty, finite set of square matrices of size n with entries in the semiring N. Consider the matrix-monoid [GRAPHICS] generated by GAMMA. We show: If GAMMA* is finite, then [GRAPHICS] where N = inverted-right-perpendicular e2.n! inverted-left-perpendicular -2. This assertion is false for any N N smaller than 2n-2. If GAMMA has exactly one member and GAMMA* is finite, then [GRAPHICS] (g denotes Landau's function). In the last assertion N is V minimal.","Title: Program Analysis through Finite Tree Automata\nYear: 2009\n\nAbstract: Dynamic Pushdown Networks (dpn's) have recently been introduced as a convenient abstraction of systems which provide recursive procedure calls and spawning of concurrent tasks such as Java programs [1, 4-6]. We show how the executions of dpn's can naturally be represented through ranked trees. The configuration reached by a program execution then can be read off from the sequence of leaves of this execution tree. This observation allows us to reduce decision problems such as reachability of configurations within a regular set for dpn's to standard decision problems for finite tree automata.","Title: Computing game values for crash games\nYear: 2007\n\nAbstract: We consider crash games which are a generalization of parity games in which the play value of a play is an integer, -∞ or ∞. In particular, the play value of a finite play is given as the sum of the payoffs of the moves of the play. Accordingly, one player aims at maximizing the play value whereas the other player aims at minimizing this value. We show that the game value of such a crash game at position v, i.e., the least upper bounds to the minimal play value that can be enforced by the maximum player in a play starting at v, can be characterized by a hierarchical system of simple integer equations. Moreover, we present a practical algorithm for solving such systems. The run-time of our algorithm (w.r.t. the uniform cost measure) is independent of the sizes of occurring numbers. Our method is based on a strategy improvement algorithm. The efficiency of our algorithm is comparable to the efficiency of the discrete strategy improvement algorithm developed by Vöge and Jurdzinski for the simpler Boolean case of parity games [19].","Title: Enriched MU-Calculi Module Checking\nYear: 2008\n\nAbstract: The model checking problem for open finite-state systems (called module checking) has been intensively studied in the literature with respect to CTL and CTL*. In this paper, we focus on module checking with respect to the fully enriched mu-calculus and some of its fragments. Fully enriched p-calculus is the extension of the propositional p-calculus with inverse programs, graded modalities, and nominals. The fragments we consider here are obtained by dropping at least one of the additional constructs. For the full calculus, we show that module checking is undecidable by using a reduction from the domino problem. For its fragments, instead, we show that module checking is decidable and EXPTIME-complete. This result is obtained by using, for the upper bound, a classical automata-theoretic approach via Forest Enriched Automata and, for the lower bound, a reduction from the module checking problem for CTL, known to be EXPTIME-hard.","Title: Extending H1-clauses with disequalities\nYear: 2011\n\nAbstract: The class H\"1 has proven particularly useful for the analysis of term-manipulating programs such as cryptographic protocols. Here, we show that clauses from that class can be extended with disequalities between arbitrary terms while retaining decidability of satisfiability. The proof is based on a normalization procedure together with a procedure to decide whether a finite automaton with disequalities accepts less than k elements, and a subtle combinatorial argument to prove that only finitely many disequalities need to be considered.","Title: Relational abstract interpretation for the verification of 2-hypersafety properties\nYear: 2013\n\nAbstract: Information flow properties of programs can be formalized as hyperproperties specifying the relation of multiple executions. In this paper, we therefore introduce a framework for proving 2-hypersafety properties by means of abstract interpretation. The main idea is to apply abstract interpretation on the self-compositions of the control flow graphs of programs. As a result, our method is inherently capable of analyzing relational properties of even dissimilar programs. Constructing self-compositions of control flow graphs is nontrivial. Therefore, we present an algorithm for constructing quality self-compositions driven by a tree distance measure between the abstract syntax trees of subprograms. Finally, we demonstrate the applicability of the approach by proving intricate information flow properties of programs written in a simple language for tree manipulation motivated by the Web Services Business Process Execution Language.","Title: Interprocedurally analysing linear inequality relations\nYear: 2007\n\nAbstract: In this paper we present an alternative approach to interprocedurally inferring linear inequality relations. We propose an abstraction of the effects of procedures through convex sets of transition matrices. In the absence of conditional branching, this abstraction can be characterised precisely by means of the least solution of a constraint system. In order to handle conditionals, we introduce auxiliary variables and postpone checking them until after the procedure calls. In order to obtain an effective analysis, we approximate convex sets by means of polyhedra. Since our implementation of function composition uses the frame representation of polyhedra, we rely on the subclass of simplices to obtain an efficient implementation. We show that for this abstraction the basic operations can be implemented in polynomial time. First practical experiments indicate that the resulting analysis is quite efficient and provides reasonably precise results.","Title: Integer Constraints to Stop Deforestation\nYear: 1996\n\nAbstract: . Deforestation is a transformation of functional programs toremove intermediate data structures. It is based on outermost unfoldingof function calls where folding occurs when unfolding takes placewithin the same nested function call. Since unrestricted unfolding mayencounter arbitrarily many terms, a termination analysis has to determinethose subterms where unfolding is possibly dangerous. We showthat such an analysis can be obtained from a control flow analysis by anextension...","Title: On the complexity of equational horn clauses\nYear: 2005\n\nAbstract: Security protocols employing cryptographic primitives with algebraic properties are conveniently modeled using Horn clauses modulo equational theories. We consider clauses corresponding to the class $\\mathcal{H}3$ of Nielson, Nielson and Seidl. We show that modulo the theory ACU of an associative-commutative symbol with unit, as well as its variants like the theory XOR and the theory AG of Abelian groups, unsatisfiability is NP-complete. Also membership and intersection-non-emptiness problems for the closely related class of one-way as well as two-way tree automata modulo these equational theories are NP-complete. A key technical tool is a linear time construction of an existential Presburger formula corresponding to the Parikh image of a context-free language. Our algorithms require deterministic polynomial time using an oracle for existential Presburger formulas, suggesting efficient implementations are possible.","Title: On the degree of ambiguity of finite automata\nYear: 1986\n\nAbstract: We investigate the ambiguity behavior of finite automata in connection with their inner structure. We show that the degree of ambiguity of a finitely ambiguous nondeterministic finite automaton (NFA) with n states is at most 5 n 2 · n n . There is a simple criterion which characterizes the infinite degree of ambiguity of an NFA, and which is decidable in polynomial time. The degree of growth of the ambiguity of an NFA is computable in polynomial time. Starting from the first result, we discuss the maximal finite degree of ambiguity of an NFA with n states, and we present subclasses of NFAs where this quantity is of order 2 Θ( n ) .","Title: Look-Ahead Removal for Top-Down Tree Transducers.\nYear: 2013\n\nAbstract: Top-down tree transducers are a convenient formalism for describing tree transformations. They can be equipped with regular look-ahead, which allows them to inspect a subtree before processing it. In certain cases, such a look-ahead can be avoided and the transformation can be realized by a transducer without look-ahead. Removing the look-ahead from a transducer, if possible, is technically highly challenging. For a restricted class of transducers with look-ahead, namely those that are total, deterministic, ultralinear, and bounded erasing, we present an algorithm that, for a given transducer from that class, (1) decides whether it is equivalent to a total deterministic transducer without look-ahead, and (2) constructs such a transducer if the answer is positive. For the whole class of total deterministic transducers with look-ahead we present a similar algorithm, which assumes that a so-called difference bound is known for the given transducer. The designer of a transducer can usually also determine a difference bound for it.","Title: Binary queries for document trees\nYear: 2004\n\nAbstract: Motivated by XML applications, we address the problem of answering k-ary queries, i.e. simultaneously locating k nodes of an input tree as specified by a given relation. In particular, we discuss how binary queries can be used as a means of navigation in XML document transformations. We introduce a grammar-based approach to specifying k-ary queries. An efficient tree-automata based implementation of unary queries is reviewed and the extensions needed in order to implement k-ary queries are presented. In particular, an efficient solution for the evaluation of binary queries is provided and proven correct. We introduce fxgrep, a practical implementation of unary and binary queries for XML. By means of fxgrep and of the fxt XML transformation language we suggest how binary queries can be used in order to increase expressivity of rule-based transformations. We compare our work with other querying languages and discuss how our ideas can be used for other existing settings.","Title: A faster solver for general systems of equations\nYear: 1999\n\nAbstract: We present a new algorithm which computes a partial approximate solution for a system of equations. It is local in that it considers just as many variables as necessary in order to compute the values of those variables we are interested in, it is generic in that it makes no assumptions on the application domain, and it is general in that the algorithm does not depend on any specific properties of right-hand sides of equations. For instance, monotonicity is not required. However, in case the right-hand sides satisfy some weak monotonicity property, our algorithm returns the (uniquely defined) least solution. The algorithm meets the best theoretical worstcase complexity known for similar algorithms. For the application of analyzing logic languages, it also gives the best practical results on most of our real-world benchmark programs.","Title: Abstract interpretation meets convex optimization\nYear: 2012\n\nAbstract: Numerical static program analyses by abstract interpretation, e.g., the problem of inferring bounds for the values of numerical program variables, are faced with the problem that the abstract domains often contain infinite ascending chains. In order to enforce termination within the abstract interpretation framework, a widening/narrowing approach can be applied that trades the guarantee of termination against a potential loss of precision. Alternatively, recently strategy improvement algorithms have been proposed for computing numerical invariants which do not suffer the imprecision incurred by widenings. Before, strategy improvement algorithms have successfully been applied for solving two-players zero-sum games. In this article we discuss and compare max-strategy and min-strategy improvement algorithms for static program analysis. For that, the algorithms are cast within a common general framework of solving systems of fixpoint equations x-=e where the right-hand sides e are maxima of finitely many monotone and concave functions. Then we indicate how the general setting can be instantiated for inferring numerical invariants of programs based on non-linear templates.","Title: A succinct solver for ALFP\nYear: 2002\n\nAbstract: We develop a solver algorithm which allows to efficiently compute the stable model of a very expressive fragment of predicate logic. The succinct formulation of the algorithm is due to the disciplined use of continuations and memoisation. This facilitates giving a precise characterisation of the behaviour of the solver and to develop a complexity calculation which allows to obtain its formal complexity. Practical experiments on a control-flow analysis of the ambient calculus show that the solver frequently performs better than the worst-case complexity estimates.","Title: Cryptographic Analysis in Cubic Time\nYear: 2001\n\nAbstract: The spi-calculus is a variant of the polyadic π-calculus that admits symmetric cryptography and that admits expressing communication protocols in a precise though still abstract way. This paper shows that context-independent control flow analysis can be calculated in cubic time despite the fact that the spi-calculus operates over an infinite universe of values. Our approach is based on Horn Clauses with Sharing and we develop transformations to pass from the infinite to the finite and to deal with the polyadic nature of input and output. We prove that this suffices for obtaining a cubic time implementation without sacrificing precision and without making simplifying assumptions on the nature of keys.","Title: Counting in Trees for Free\nYear: 2004\n\nAbstract: it is known that MSO logic for ordered unranked trees is undecidable if Presburger constraints are allowed at children of nodes. We show here that a decidable logic is obtained if we use a modal fixpoint logic instead. We present a characterization of this logic by means of deterministic Presburger tree automata and show how it can be used to express numerical document queries. Surprisingly, the complexity of satisfiability for the extended logic is asymptotically the same as for the original fixpoint logic. The non-emptiness for Presburger tree automata (PTA) is PSPACE-complete, which is moderate given that it is already PSPACE-hard to test whether the complement of a regular expression is non-empty. We also identify a subclass of PTAs with a tractable non-emptiness problem. Further, to decide whether a tree t satisfies a formula phi is polynomial in the size of phi and linear in the size of t. A technical construction of independent interest is a linear time construction of a Presburger formula for the Parikh image of a regular language.","Title: Earliest Normal Form And Minimization For Bottom-Up Tree Transducers\nYear: 2011\n\nAbstract: We show that for every deterministic bottom-up tree transducer, a unique equivalent transducer can be constructed which is minimal. The construction is based on a sequence of normalizing transformations which, among others, guarantee that non-trivial output is produced as early as possible. For a deterministic bottom-up transducer where every state produces either none or infinitely many outputs, the minimal transducer can be constructed in polynomial time.","Title: Numerical Invariants through Convex Relaxation and Max-Strategy Iteration\nYear: 2014\n\nAbstract: We present an algorithm for computing the uniquely determined least fixpoints of self-maps on (with ) that are point-wise maximums of finitely many monotone and order-concave self-maps. This natural problem occurs in the context of systems analysis and verification. As an example application we discuss how our method can be used to compute template-based quadratic invariants for linear systems with guards. The focus of this article, however, lies on the discussion of the underlying theory and the properties of the algorithm itself.","Title: Solving systems of rational equations through strategy iteration\nYear: 2011\n\nAbstract: We present practical algorithms for computing exact least solutions of equation systems over the reals with addition, multiplication by positive constants, minimum and maximum. The algorithms are based on strategy iteration. Our algorithms can, for instance, be used for the analysis of recursive stochastic games. In the present article we apply our techniques for computing abstract least fixpoint semantics of affine programs over the relational template polyhedra domain. In particular, we thus obtain practical algorithms for computing abstract least fixpoint semantics over the abstract domains of intervals, zones, and octagons.","Title: On optimal slicing of parallel programs\nYear: 2001\n\nAbstract: Optimal program slicing determines for a statement S in a program &pgr; whether or not S affects a specified set of statements, given that all conditionals in &pgr; are interpreted as non-deterministic choices.Only recently, it has been shown that reachability of program points and hence also optimal slicing is undecidable for multi-threaded programs with (parameterless) procedures and synchronization [23]. Here, we sharpen this result by proving that slicing remains undecidable if synchronization is abandoned---although reachability becomes polynomial. Moreover, we show for multi-threaded programs without synchronization, that slicing stays PSPACE-hard when procedure calls are forbidden, and becomes NP-hard for loop-free programs. Since the latter two problems can be solved in PSPACE and NP, respectively, even in presence of synchronization, our new lower bounds are tight.Finally, we show that the above decidability and lower bound properties equally apply to other simple program analysis problems like copy constant propagation and true liveness of variables. This should be contrasted to the problems of strong copy constant propagation and (ordinary) liveness of variables for which polynomial algorithms have been designed [15, 14, 24].","Title: A quadratic regularity test for non-deleting macro S grammars\nYear: 1985\n\nAbstract: A quadratic regularity test is presented for non-deleting simple deterministic contextfree tree grammars as well as for non-deleting macro S grammars.","Title: Region Analysis for Race Detection\nYear: 2009\n\nAbstract: Automatic race detection of C programs requires fast, yet sufficiently precise analysis of dynamic memory. Therefore, we present\n a region-based pointer analysis which seeks to identify disjoint regions of dynamically allocated objects to ensure that write accesses to the same region are always protected by the same mutexes.\n Our approach has been implemented within the interprocedural analyzer of concurrent C programs GobLint and we have successfully\n applied it on code from the Linux kernel, such as the access vector cache. This code relies on a synchronized hash table where\n an array of doubly linked lists is protected by an array of locks.","Title: On distributive fixed-point expressions\nYear: 1999\n\nAbstract: For every fixed-point expression e of alternation-depth r, we construct a new fixed-point expression e' of alternation-depth 2 and size O(r . \\e\\). Expression e' is equivalent to e whenever operators are distributive and the underlying complete lattice has a co-continuous least upper bound. We show that our transformation is optimal not only w.r.t. alternation-depth but also w.r.t. the increase in size of the resulting expression. AMS Subject Classification. 68Q60, 03D70, 06D99, 68Q25.","Title: Normalization of linear horn clauses\nYear: 2010\n\nAbstract: Nielson et al. [12] exhibit a rich class of Horn clauses which they call H1. Least models of finite sets of H1 Horn clauses are regular tree languages. Nielson et al. [12] describe a normalization procedure for computing least models of finite sets of H1 Horn clauses in the form of tree automata. In the present paper, we simplify and extend this normalization procedure to a semi-procedure that deals with finite sets of linear Horn clauses. The extended semi-procedure does not terminate in general but does so on useful subclasses of finite sets of linear Horn clauses. The extension in particular coincides with the normalization procedure of Nielson et al. [12] for sets of H1 Horn clauses. In order to demonstrate the usefulness of the extension, we show how backward reachability analysis for constrained dynamic pushdown networks (see Bouajjani et al. [3]) can be encoded into a class of finite sets of linear Horn clauses for which our normalization procedure terminates after at most exponentially many steps.","Title: Fast interprocedural linear two-variable equalities\nYear: 2011\n\nAbstract: In this article we provide an interprocedural analysis of linear two-variable equalities. The novel algorithm has a worst-case complexity of 𝒪(n ⋅ k4), where k is the number of variables and n is the program size. Thus, it saves a factor of k4 in comparison to a related algorithm based on full linear algebra. We also indicate how the practical runtime can be further reduced significantly. The analysis can be applied, for example, for register coalescing, for identifying local variables and thus for interprocedurally observing stack pointer modifications as well as for an analysis of array index expressions, when analyzing low-level code.","Title: Polynomial Precise Interval Analysis Revisited\nYear: 2009\n\nAbstract: We consider a class of arithmetic equations over the complete lattice of integers (extended with -驴 and 驴) and provide a polynomial time algorithm for computing least solutions. For systems of equations with addition and least upper bounds, this algorithm is a smooth generalization of the Bellman-Ford algorithm for computing the single source shortest path in presence of positive and negative edge weights. The method then is extended to deal with more general forms of operations as well as minima with constants. For the latter, a controlled widening is applied at loops where unbounded increase occurs. We apply this algorithm to construct a cubic time algorithm for the class of interval equations using least upper bounds, addition, intersection with constant intervals as well as multiplication.","Title: Join-lock-sensitive forward reachability analysis for concurrent programs with dynamic process creation\nYear: 2011\n\nAbstract: Dynamic Pushdown Networks (DPNs) are a model for parallel programs with (recursive) procedures and dynamic process creation. Constraints on the sequences of spawned processes allow to extend the basic model with joining of created processes [2]. Orthogonally DPNs can be extended with nested locking [9]. Reachability of a regular set R of configurations in presence of stable constraints as well as reachability without constraints but with nested locking are based on computing the set of predecessors pre* (R). In the present paper, we present a forward-propagating algorithm for deciding reachability for DPNs. We represent sets of executions by sets of execution trees and show that the set of all execution trees resulting in configurations from R which either allow a lock-sensitive execution or a join-sensitive execution, is regular. Here, we rely on basic results about macro tree transducers. As a second contribution, we show that reachability is decidable also for DPNs with both nested locking and joins.","Title: Shape analysis of low-level c with overlapping structures\nYear: 2010\n\nAbstract: Device drivers often keep data in multiple data structures simultaneously while embedding list or tree related records into the records containing the actual data; this results in overlapping structures. Shape analyses have traditionally relied on a graph-based representation of memory where a node corresponds to a whole record and edges to pointers. As this is ill-suited for encoding overlapping structures, we propose and formally relate two refined memory models. We demonstrate the appropriateness of these models by implementing shape analyses based on them within the TVLA framework. The implementation is exemplified using code extracted from cache managing kernel modules.","Title: Synchronized Tree Languages Revisited and New Applications\nYear: 2001\n\nAbstract: We present a new formulation for tree-tuple synchronized languages, much simpler than the existing one. This new formulation allows us to prove stronger structural results. As a consequence, synchronized languages give rise to new applications : - to rewriting : given tree languages L1 (synchronized), L2 (regular), Rel(L1) ⊆ L2 is decidable for several rewrite-like relations Rel. - to concurrency : we prove decidability of the logic EF for a process calculus allowing some bounded form of communication. Consequently, the absence of deadlocks is decidable.","Title: How to combine widening and narrowing for non-monotonic systems of equations\nYear: 2013\n\nAbstract: Non-trivial analysis problems require complete lattices with infinite ascending and descending chains. In order to compute reasonably precise post-fixpoints of the resulting systems of equations, Cousot and Cousot have suggested accelerated fixpoint iteration by means of widening and narrowing. The strict separation into phases, however, may unnecessarily give up precision that cannot be recovered later. While widening is also applicable if equations are non-monotonic, this is no longer the case for narrowing. A narrowing iteration to improve a given post-fixpoint, additionally, must assume that all right-hand sides are monotonic. The latter assumption, though, is not met in presence of widening. It is also not met by equation systems corresponding to context-sensitive interprocedural analysis, possibly combining context-sensitive analysis of local information with flow-insensitive analysis of globals. As a remedy, we present a novel operator that combines a given widening operator with a given narrowing operator. We present adapted versions of round-robin as well as of worklist iteration, local, and side-effecting solving algorithms for the combined operator and prove that the resulting solvers always return sound results and are guaranteed to terminate for monotonic systems whenever only finitely many unknowns (constraint variables) are encountered.","Title: A Smooth Combination of Linear and Herbrand Equalities for Polynomial Time Must-Alias Analysis\nYear: 2009\n\nAbstract: We present a new domain for analyzing must -equalities between address expressions. The domain is a smooth combination of Herbrand and affine equalities which enables us to describe field accesses and array indexing. While the full combination of uninterpreted functions with affine arithmetics results in intractable assertion checking algorithms, our restricted domain allows us to construct an analysis of address must -equalities that runs in polynomial time. We indicate how this analysis can be applied to infer access patterns in programs manipulating arrays and structs.","Title: Weakly Regular Relations and Applications\nYear: 2001\n\nAbstract: A new class of tree-tuple languages is introduced: the weakly regular relations. It is an extension of the regular case (regular relations) and a restriction of tree-tuple synchronized languages, that has all usual nice properties, except closure under complement. Two applications are presented: to unification modulo a rewrite system, and to one-step rewriting.","Title: Bottom-up tree automata with term constraints\nYear: 2010\n\nAbstract: We introduce bottom-up tree automata with equality and disequality term constraints. These constraints are more expressive than the equality and disequality constraints between brothers introduced by Bogaert and Tison in 1992. Our new class of automata is still closed under Boolean operations. Moreover, we show that for tree automata with term constraints not only membership but also emptiness is decidable. This contrasts with the undecidability of emptiness for automata with arbitrary equality constraints between subterms identified by paths as shown in 1981 by Mongy.","Title: A Modal Mu-Calculus for Durational Transition Systems\nYear: 1996\n\nAbstract: Durational transition systems are finite transition systems where every transition is additionally equipped with a duration. We consider the problem of interpreting $\\mu$--formulas over durational transition systems. In case the formula contains only operations minimum, maximum, addition, and sequencing, we show that the interpretation ist not only computable but (up to a linear factor) as efficiently computable as the interpretation of $\\mu$--formulas over ordinary finite transition systems.","Title: Characterizing Complexity Classes by Higher Type Primitive Recursive Definitions, Part II\nYear: 1990\n\nAbstract: Higher type primitive recursive definitions (also known as Gödel's system T) defining first-order functions (i.e. functions of type ind→...→ind→ind, ind for individuals, higher types occur in between) can be classified into an infinite syntactic hierarchy: A definition is in the n'th stage of this hierarchy, a so called rank-n-definition, iff n is an upper bound on the levels of the types occurring in it.","Title: Normalizable Horn Clauses, Strongly Recognizable Relations, and Spi\nYear: 2002\n\nAbstract: We exhibit a rich class of Horn clauses, which we call H1, whose least models, though possibly infinite, can be computed effectively. We show that the least model of an H1 clause consists of so-called strongly recognizable relations and present an exponential normalization procedure to compute it. In order to obtain a practical tool for program analysis, we identify a restriction of H1 clauses, which we call H2, where the least models can be computed in polynomial time. This fragment still allows to express, e.g., Cartesian product and transitive closure of relations. Inside H2, we exhibit a fragment H3 where normalization is even cubic. We demonstrate the usefulness of our approach by deriving a cubic control-flow analysis for the Spi calculus [1] as presented in [14].","Title: Finite tree automata with cost functions\nYear: 1994\n\nAbstract: Cost functions for tree automata are mappings from transitions to (tuples of) polynomials over some semiring. We consider four semirings, namely, N the semiring of nonnegative integers, A the ''arctical semiring'', T the tropical semiring and F the semiring of finite subsets of nonnegative integers. We show: for semirings N and A it is decidable in polynomial time whether or not the costs of accepting computations is bounded; for F it is decidable in polynomial time whether or not the cardinalities of occurring cost sets are bounded. In all three cases, we derive explicit upper bounds. For semiring T, we prove decidability of boundedness as well, but obtain a polynomial-time algorithm only in case that the degrees of occurring polynomials are at most 1.","Title: What is a pure functional?\nYear: 2010\n\nAbstract: Given an ML function f : (int → int) → int how can we rigorously specify that f is pure, i.e., produces no side-effects other than those arising from calling its functional argument? We show that existing methods based on preservation of invariants and relational parametricity are insufficient for this purpose and thus define a new notion that captures purity in the sense that for any functional F that is pure in this sense there exists a corresponding question-answer strategy. This research is motivated by an attempt to prove algorithms correct that take such supposedly pure functionals as input and apply them to stateful arguments in order to inspect intensional aspects of their behaviour.","Title: Upper adjoints for fast inter-procedural variable equalities\nYear: 2008\n\nAbstract: We present a polynomial-time algorithm which at the extra cost of a factor O(k) (k the number of variables) generalizes inter-procedural copy constant propagation. Our algorithm infers variable-variable equalities in addition to equalities between variables and constants. Like copy constant propagation, it tracks constant and copying assignments but abstracts more complex assignments and guards. The algorithm is based on the observation that, for the abstract lattice of consistent equivalence relations, the upper adjoints of summary functions can be represented much more succinctly than summary functions themselves.","Title: Flat and One-Variable Clauses for Single Blind Copying Protocols: The XOR Case\nYear: 2009\n\nAbstract: In cryptographic protocols with the single blind copying restriction, at most one piece of unknown data is allowed to be copied in each step of the protocol. The secrecy problem for such protocols can be modeled as the satisfiability problem for the class of first-order Horn clauses called flat and one-variable Horn clauses, and is known to be DEXPTIME-complete. We show that when an XOR operator is additionally present, then the secrecy problem is decidable in 3-EXPTIME. We also note that replacing XOR by the theory of associativity-commutativity or by the theory of Abelian groups, or removing some of the syntactic restrictions on the clauses, leads to undecidability.","Title: Tree automata for code selection\nYear: 1991\n\nAbstract: We deal with the generation of code selectors in compiler backends. The fundamental concepts are systematically derived from the theory of regular tree grammars and finite tree automata. We use this general approach to construct algorithms that generalize and improve existing methods.","Title: Cryptographic protocol verification using tractable classes of horn clauses\nYear: 2006\n\nAbstract: We consider secrecy problems for cryptographic protocols modeled using Horn clauses and present general classes of Horn clauses which can be efficiently decided. Besides simplifying the methods for the class of flat and one-variable clauses introduced for modeling of protocols with single blind copying [7,25], we also generalize this class by considering k-variable clauses instead of one-variable clauses with suitable restrictions similar to those for the class S+. This class allows to conveniently model protocols with joint blind copying. We show that for a fixed k, our new class can be decided in DEXPTIME, as in the case of one variable.","Title: Deciding equivalence of top--down XML transformations in polynomial time\nYear: 2009\n\nAbstract: Many useful XML transformations can be expressed by deterministic top-down tree transducers. A normal form is presented for such transducers (extended with the facility to inspect their input trees). A transducer in normal form has a unique canonical form which can be obtained by a minimization procedure, in polynomial time. Thus, equivalence of transducers in normal form can be decided in polynomial time. If the transducer is total, the normal form can be obtained in polynomial time as well.","Title: A Type-safe Macro System for XML\nYear: 2002\n\nAbstract: XML is originally designed for the use in document processing. Every classical document processing system supports a mechanism which is called macro. In general, a macro is a named collection of actions. These actions are executed whenever the name of the macro appears in a document instance. We describe a very small but powerful macro language for XML. The presented language supports macros with arguments. As a main result we will show that for a macro expansion H and a recognizable set R the set H-1(R) of trees t, whose macro expansion H(t) are in R, is recognizable. This implies that the typechecking problem for macro expansion is decidable. A major drawback of this approach is the time complexity. Therefore we designed a practical typechecking discipline. We equip every macro definition with a type expression describing the input forests. On the basis of this type information the macro processor computes an output type for the macro. Having inferred this output type, we aim at extending the given output DTD to a DTD for admissible input possibly containing unexpanded macros.","Title: Tree Transducers and Formal Methods (Dagstuhl Seminar 13192).\nYear: 2013\n\nAbstract: The aim of this Dagstuhl Seminar was to bring together researchers from various research areas related to the theory and application of tree transducers. Recently, interest in tree transducers has been revived due to surprising new applications in areas such as XML databases, security verification, programming language theory, and linguistics. This seminar therefore aimed to inspire the exchange of theoretical results and information regarding the practical requirements related to tree transducers.","Title: Constraint-Based Inter-Procedural Analysis of Parallel Programs\nYear: 2000\n\nAbstract: We provide a uniform framework for the analysis of programs with procedures and explicit, unbounded, fork/join parallelism covering not only bitvector problems like reaching definitions or live variables but also non-bitvector problems like simple constant propagation. Due to their structural similarity to the sequential case, the resulting algorithms are as efficient as their widely accepted sequential counterparts, and they can easily be integrated in existing program analysis environments like e.g. METAFRAME or PAG. We are therefore convinced that our method will soon find its way into industrial-scale computer systems.","Title: Runtime enforcement of information flow security in tree manipulating processes\nYear: 2012\n\nAbstract: We consider the problem of enforcing information flow policies in Xml manipulating programs such as Web services and business processes implemented in current workflow languages. We propose a runtime monitor that can enforce the secrecy of freely chosen subtrees of the data throughout the execution. The key idea is to apply a generalized constant propagation for computing the public effect of branching constructs whose conditions may depend on the secret. This allows for a better precision than runtime monitors which rely on tainting of variables or nodes alone. We demonstrate our approach for a minimalistic tree manipulating programming language and prove its correctness w.r.t. the concrete semantics of programs.","Title: Propagating differences: an efficient new fixpoint algorithm for distributive constraint systems\nYear: 1998\n\nAbstract: Integrating semi-naive fixpoint iteration from deductive data bases [3, 2, 4] as well as continuations into worklist-based solvers, we derive a new application independent local fixpoint algorithm for distributive constraint systems. Seemingly different efficient algorithms for abstract interpretation like those for linear constant propagation for imperative languages [16] as well as for control-flow analysis for functional languages [12] turn out to be instances of our scheme. Besides this systematizing contribution we also derive a new efficient algorithm for abstract OLDT-resolution as considered in [14, 15, 24] for Prolog.","Title: Formalising the pi-calculus using nominal logic\nYear: 2009\n\nAbstract: We formalise the pi-calculus using the nominal datatype package, a package based on ideas from the nominal logic by Pitts et al., and demonstrate an implementation in Isabelle/HOL. The purpose is to derive powerful induction rules for the semantics in order to conduct machine checkable proofs, closely following the intuitive arguments found in manual proofs. In this way we have covered many of the standard theorems of bisimulation equivalence and congruence, both late and early, and both strong and weak in a unison manner. We thus provide one of the most extensive formalisations of a process calculus ever done inside a theorem prover. A significant gain in our formulation is that agents are identified up to alpha-equivalence, thereby greatly reducing the arguments about bound names. This is a normal strategy for manual proofs about the pi-calculus, but that kind of hand waving has previously been difficult to incorporate smoothly in an interactive theorem prover. We show how the nominal logic formalism and its support in Isabelle accomplishes this and thus significantly reduces the tedium of conducting completely formal proofs. This improves on previous work using weak higher order abstract syntax since we do not need extra assumptions to filter out exotic terms and can keep all arguments within a familiar first-order logic.","Title: Computing relaxed abstract semantics w.r.t. quadratic zones precisely\nYear: 2010\n\nAbstract: In the present paper we compute numerical invariants of programs by abstract interpretation. For that we consider the abstract domain of quadratic zones recently introduced byAdjé et al. [2]. We use a relaxed abstract semantics which is at least as precise as the relaxed abstract semantics of Adjé et al. [2]. For computing our relaxed abstract semantics, we present a practical strategy improvement algorithm for precisely computing least solutions of fixpoint equation systems, whose right-hand sides use order-concave operators and the maximum operator. These fixpoint equation systems strictly generalize the fixpoint equation systems considered by Gawlitza and Seidl [11].","Title: Model checking information flow in reactive systems\nYear: 2012\n\nAbstract: Most analysis methods for information flow properties do not consider temporal restrictions. In practice, however, such properties rarely occur statically, but have to consider constraints such as when and under which conditions a variable has to be kept secret. In this paper, we propose a natural integration of information flow properties into linear-time temporal logics (LTL). We add a new modal operator, the hide operator, expressing that the observable behavior of a system is independent of the valuations of a secret variable. We provide a complexity analysis for the model checking problem of the resulting logic SecLTL and we identify an expressive fragment for which this question is efficiently decidable. We also show that the path based nature of the hide operator allows for seamless integration into branching time logics.","Title: When Is a Functional Tree Transduction Deterministic?\nYear: 1993\n\nAbstract: We give a decision procedure to determine whether or not the transduction of a functional transducer can be realized by a deterministic (resp. reduced deterministic) transducer. In case this is possible we exhibit a general construction to build this transducer.","Title: Approximative Methods for Monotone Systems of Min-Max-Polynomial Equations\nYear: 2008\n\nAbstract: On the Internet, there are advertisements (ads) of different kinds: image, text, video and other specially marked objects that are distinct from the underlying content of the page. There is an industry behind the management of such ads, and they face ...","Title: An Even Faster Solver for General Systems of Equations\nYear: 1996\n\nAbstract: . We present a new algorithm which computes a partial approximatesolution for a system of equations. It is local in that it considersas few variables as necessary in order to compute the values of thosevariables we are interested in, it is generic in that it makes no assumptionson the application domain, and it is general in that the algorithmdoes not depend on any specific properties of right-hand sides of equations.For instance, monotonicity is not required. However, in case the...","Title: Efficiently intertwining widening and narrowing.\nYear: 2015\n\nAbstract: A warrowing operator is constructed which combines widening and narrowing.Variations of standard fixpoint algorithms are equipped with the new operator.For the resulting solvers, termination is proven under liberal assumptions.Experiments indicate that precision may be increased significantly at a decent cost. Accelerated fixpoint iteration by means of widening and narrowing is the method of choice for solving systems of equations over domains with infinite ascending chains. The strict separation into an ascending widening and a descending narrowing phase, however, may unnecessarily give up precision that cannot be recovered later. It is also unsuitable for equation systems with infinitely many unknowns - where local solving must be used.As a remedy, we present a novel operator ¿ that combines a given widening operator ¿ with a given narrowing operator Δ. We present adapted versions of round-robin and worklist iteration as well as local and side-effecting solving algorithms for the combined operator ¿. We prove that the resulting solvers always return sound results and are guaranteed to terminate for monotonic systems whenever only finitely many unknowns are encountered.","Title: Parametric Strategy Iteration.\nYear: 2014\n\nAbstract: Program behavior may depend on parameters, which are either configured before compilation time, or provided at run-time, e.g., by sensors or other input devices. Parametric program analysis explores how different parameter settings may affect the program behavior. In order to infer invariants depending on parameters, we introduce parametric strategy iteration. This algorithm determines the precise least solution of systems of integer equations depending on surplus parameters. Conceptually, our algorithm performs ordinary strategy iteration on the given integer system for all possible parameter settings in parallel. This is made possible by means of region trees to represent the occurring piecewise affine functions. We indicate that each required operation on these trees is polynomial-time if only constantly many parameters are involved. Parametric strategy iteration for systems of integer equations allows to construct parametric integer interval analysis as well as parametric analysis of differences of integer variables. It thus provides a general technique to realize precise parametric program analysis if numerical properties of integer variables are of concern.","Title: Inter-procedural Two-Variable Herbrand Equalities.\nYear: 2014\n\nAbstract: We prove that all valid Herbrand equalities can be inter-procedurally inferred for programs where all assignments whose right-hand sides depend on at most one variable are taken into account. The analysis is based on procedure summaries representing the weakest pre-conditions for finitely many generic post-conditions with template variables. In order to arrive at effective representations for all occurring weakest pre-conditions, we show for almost all values possibly computed at run-time, that they can be uniquely factorized into tree patterns and a ground term. Moreover, we introduce an approximate notion of subsumption which is effectively decidable and ensures that finite conjunctions of equalities may not grow infinitely. Based on these technical results, we realize an effective fixpoint iteration to infer all inter-procedurally valid Herbrand equalities for these programs. Finally we show that an invariant candidate with a constant number of variables, can be verified in polynomial time.","Title: Language support for synchronous parallel critical sections\nYear: 1995\n\nAbstract: We introduce a new parallel programming paradigm, namely synchronous parallel critical sections. Such parallel critical sections must be seen in the context of switching between synchronous and asynchronous modes of computation. Thread farming allows to generate bunches of threads to solve independent subproblems asynchronously and in parallel. Opposed to that, synchronous parallel critical sections allow to organize bunches of asynchronous parallel threads to execute certain tasks jointly and synchronously. We show how the PRAM language Fork95 can be extended by a construct \"join\" supporting parallel critical sections. We explain its semantics and implementation, and discuss possible applications.","Title: Enhancing Top-Down Solving with Widening and Narrowing.\nYear: 2016\n\nAbstract: We present an enhancement of the generic fixpoint algorithm TD which can deal with widening and narrowing even for non-monotonic systems of equations. In contrast to corresponding enhancements proposed for other standard fixpoint algorithms, no extra priorities on variables are required. Still, a mechanism can be devised so that occurrences of the widening/narrowing operator are inserted as well as removed dynamically.","Title: An Analysis of Universal Information Flow Based on Self-Composition\nYear: 2015\n\nAbstract: We introduce a novel way of proving information flow properties of a program based on its self-composition. Similarly to the universal information flow type system of Hunt and Sands, our analysis explicitly computes the dependencies of variables in the final state on variables in the initial state. Accordingly, the analysis result is independent of specific information flow lattices, and allows to derive information flow w.r.t. any of these. While our analysis runs in polynomial time, we prove that it never loses precision against the type system of Hunt and Sands, and may gain extra precision by taking similarities between different branches of conditionals into account. Also, we indicate how it can be smoothly generalized to an interprocedural analysis.","Title: Equivalence of Deterministic Top-Down Tree-to-String Transducers is Decidable.\nYear: 2015\n\nAbstract: We show that equivalence of deterministic top-down tree-to-string transducers is decidable, thus solving a long standing open problem in formal language theory. We also present efficient algorithms for subclasses: polynomial time for total transducers with unary output alphabet (over a given top-down regular domain language), and co-randomized polynomial time for linear transducers, these results are obtained using techniques from multi-linear algebra. For our main result, we prove that equivalence can be certified by means of inductive invariants using polynomial ideals. This allows us to construct two semi-algorithms, one searching for a proof of equivalence, one for a witness of non-equivalence.","Title: Enforcing Termination of Interprocedural Analysis.\nYear: 2016\n\nAbstract: Interprocedural analysis by means of partial tabulation of summary functions may not terminate when the same procedure is analyzed for infinitely many abstract calling contexts or when the abstract domain has infinite strictly ascending chains. As a remedy, we present a novel local solver for general abstract equation systems, be they monotonic or not, and prove that this solver fails to terminate only when infinitely many variables are encountered. We clarify in which sense the computed results are sound. Moreover, we show that interprocedural analysis performed by this novel local solver, is guaranteed to terminate for all non-recursive programs—irrespective of whether the complete lattice is infinite or has infinite strictly ascending or descending chains.","Title: Static race detection for device drivers: the Goblint approach.\nYear: 2016\n\nAbstract: Device drivers rely on fine-grained locking to ensure safe access to shared data structures. For human testers, concurrency makes such code notoriously hard to debug; for automated reasoning, dynamically allocated memory and low-level pointer manipulation poses significant challenges. We present a flexible approach to data race analysis, implemented in the open source Goblint static analysis framework, that combines different pointer and value analyses in order to handle a wide range of locking idioms, including locks allocated dynamically as well as locks stored in arrays. To the best of our knowledge, this is the most ambitious effort, having lasted well over ten years, to create a fully automated static race detection tool that can deal with most of the intricate locking schemes found in Linux device drivers. Our evaluation shows that these analyses are sufficiently precise, but practical use of these techniques requires inferring environmental and domain-specific assumptions.","Title: Reachability For Dynamic Parametric Processes\nYear: 2017\n\nAbstract: In a dynamic parametric process every subprocess may spawn arbitrarily many, identical child processes, that may communicate either over global variables, or over local variables that are shared with their parent. We show that reachability for dynamic parametric processes is decidable under mild assumptions. These assumptions are e.g. met if individual processes are realized by pushdown systems, or even higher-order pushdown systems. We also provide algorithms for subclasses of pushdown dynamic parametric processes, with complexity ranging between NP and DEXPTIME.","Title: Specifying and Verifying Secrecy in Workflows with Arbitrarily Many Agents.\nYear: 2016\n\nAbstract: Web-based workflow management systems, like EasyChair, HealthVault, Ebay, or Amazon, often deal with confidential information such as the identity of reviewers, health data, or credit card numbers. Because the number of participants in the workflow is in principle unbounded, it is difficult to describe the information flow policy of such systems in specification languages that are limited to a fixed number of agents. We introduce a first-order version of HyperLTL, which allows us to express information flow requirements in workflows with arbitrarily many agents. We present a bounded model checking technique that reduces the violation of the information flow policy to the satisfiability of a first-order formula. We furthermore identify conditions under which the resulting satisfiability problem is guaranteed to be decidable.","Title: Computing the longest common prefix of a context-free language in polynomial time.\nYear: 2018\n\nAbstract: We present two structural results concerning the longest common prefixes of non-empty languages. First, we show that the longest common prefix of the language generated by a context-free grammar of size N equals the longest common prefix of the same grammar where the heights of the derivation trees are bounded by 4N. Second, we show that each non-empty language L has a representative subset of at most three elements which behaves like L w.r.t. the longest common prefix as well as w.r.t. longest common prefixes of L after unions or concatenations with arbitrary other languages. From that, we conclude that the longest common prefix, and thus the longest common suffix, of a context-free language can be computed in polynomial time.","Title: Verifying Security Policies in Multi-agent Workflows with Loops.\nYear: 2017\n\nAbstract: We consider the automatic verification of information flow security policies of web-based workflows, such as conference submission systems like EasyChair. Our workflow description language allows for loops, non-deterministic choice, and an unbounded number of participating agents. The information flow policies are specified in a temporal logic for hyperproperties. We show that the verification problem can be reduced to the satisfiability of a formula of first-order linear-time temporal logic, and provide decidability results for relevant classes of workflows and specifications. We report on experimental results obtained with an implementation of our approach on a series of benchmarks.","Title: Formal Methods of Transformations (Dagstuhl Seminar 17142).\nYear: 2017\n\nAbstract: The goal of this Dagstuhl seminar was to gather researchers working on the theory and practice of transformations (also know as transductions) of word and tree structures, which are realised by transducers (automata with outputs). This seminar was motivated by recent advances and breakthrough results, both in the settings of words and trees.","Title: Balancedness of MSO transductions in polynomial time.\nYear: 2018\n\nAbstract: We show that MSO definable tree-to-string transductions with a fixed copy number, given as top-down tree-to-string transducers with fixed copying-bound, can be checked for balancedness of all output strings in polynomial time. We also present an upper bound for the copying bound for deterministic top-down transducers and show that in general, balancedness of output languages of deterministic finite-copying top-down tree-to-string transducers is DExptime-hard.","Title: Inductive Invariants for Noninterference in Multi-agent Workflows\nYear: 2018\n\nAbstract: Our goal is to certify absence of information leaks in multi-agent workflows, such as conference management systems like EasyChair. These workflows can be executed by any number of agents some of which may form coalitions against the system. Therefore, checking noninterference is a challenging problem. Our paper offers two main contributions: First, a technique is provided to translate noninterference (in presence of various agent capabilities and declassification conditions) into universally quantified invariants of an instrumented new workflow program. Second, general techniques are developed for checking and inferring universally quantified inductive invariants for workflow programs. In particular, a large class of workflows is identified where inductiveness of invariants is decidable, as well as a smaller, still useful class of workflows where the weakest inductive universal invariant implying the desired invariant, is effectively computable. The new algorithms are implemented and applied to certify noninterference for workflows arising from conference management systems.","Title: Least Solutions of Equations over N\nYear: 1994\n\nAbstract: We consider the problem of computing the least solution X\n\ni\n, i=1,..., n, of a system of equations x\ni=f\ni, i=1,..., n, over N, i.e., the naturals (extended by ), where the right hand sides f\ni are expressions built up from constants and variables by operations taken from some set . We present efficient algorithms for various subsets of the operations minimum, maximum, addition and multiplication.","Title: Exact XML type checking in polynomial time\nYear: 2007\n\nAbstract: Stay macro tree transducers (smtts) are an expressive formalism for reasoning about XSLT-like document transformations. Here, we consider the exact type checking problem for smtts. While the problem is decidable, the involved technique of inverse type inference is known to have exponential worst-case complexity (already for top-down transformations without parameters). We present a new adaptive type checking algorithm based on forward type inference through exact characterizations of output languages. The new algorithm correctly type-checks all call-by-value smtts. Given that the output type is specified by a deterministic automaton, the algorithm is polynomial-time whenever the transducer uses only few parameters and visits every input node only constantly often. Our new approach can also be generalized from smtts to stay macro forest transducers which additionally support concatenation as built-in output operation.","Title: Checking herbrand equalities and beyond\nYear: 2005\n\nAbstract: A Herbrand equality between expressions in a program is an equality which holds relative to the Herbrand interpretation of operators. We show that the problem of checking validity of positive Boolean combinations of Herbrand equalities at a given program point is decidable – even in presence of disequality guards. This result vastly extends the reach of classical methods for global value numbering which cannot deal with disjunctions and are always based on an abstraction of conditional branching with non-deterministic choice. In order to introduce our analysis technique in a simpler scenario we also give an alternative proof that in the classic setting, where all guards are ignored, conjunctions of Herbrand equalities can be checked in polynomial time. As an application of our method, we show how to derive all valid Herbrand constants in programs with disequality guards. Finally, we present a PSPACE lower bound and show that in presence of equality guards instead of disequality guards, it is undecidable to check whether a given Herbrand equality holds or not.","Title: Proving Absence of Starvation by Means of Abstract Interpretation and Model Checking.\nYear: 2017\n\nAbstract: The Avionics Application Software Standard Interface ARINC 653 is meant to increase predictability of safety-critical software systems. It allows to coordinate multiple tasks by means of priorities, semaphores, setting and waiting for events as well as by sending suspend and resume signals. Thus, it is a major challenge to verify that no such tightly coupled task gets ultimately stuck, e.g., by infinitely waiting for an event or a resume signal by another task. We explain how abstract interpretation together with model checking may nicely cooperate to guarantee absence of such concurrency flaws and report on practical experiments.","Title: Deciding Equivalence of Separated Non-nested Attribute Systems in Polynomial Time.\nYear: 2019\n\nAbstract: In 1982, Courcelle and Franchi-Zannettacci showed that the equivalence problem of separated non-nested attribute systems can be reduced to the equivalence problem of total deterministic separated basic macro tree transducers. They also gave a procedure for deciding equivalence of transducer in the latter class. Here, we reconsider this equivalence problem. We present a new alternative decision procedure and prove that it runs in polynomial time. We also consider extensions of this result to partial transducers and to the case where parameters of transducers accumulate strings instead of trees.","Title: Improving Thread-Modular Abstract Interpretation\nYear: 2021\n\nAbstract: We give thread-modular non-relational value analyses as abstractions of a local trace semantics. The semantics as well as the analyses are formulated by means of global invariants and side-effecting constraint systems. We show that a generalization of the analysis provided by the static analyzer GOBLINT as well as a natural improvement of Antoine Mine's approach can be obtained as instances of this general scheme. We show that these two analyses are incomparable w.r.t. precision and provide a refinement which improves on both precision-wise. We also report on a preliminary experimental comparison of the given analyses on a meaningful suite of benchmarks.","Title: On The Balancedness Of Tree-To-Word Transducers\nYear: 2021\n\nAbstract: A language over an alphabet B= A boolean OR (A) over bar of opening (A) and closing ((A) over bar) brackets, is balanced if it is a subset of the Dyck language D-B over B, and it is well-formed if all words are prefixes of words in D-B. We show that well-formedness of a context-free language is decidable in polynomial time, and that the longest common reduced suffix can be computed in polynomial time. With this at a hand we decide for the class 2-TW of non-linear tree transducers with output alphabet B whether or not the output language is balanced.","Title: Three improvements to the top-down solver\nYear: 2021\n\nAbstract: The local solver TD is a generic fixpoint engine which explores a given system of equations on demand. It has been successfully applied to the interprocedural analysis of procedural languages. The solver TD gains efficiency by detecting dependencies between unknowns on the fly. This algorithm has been recently extended to deal with widening and narrowing as well. In particular, it has been equipped with an automatic detection of widening and narrowing points. That version, however, is only guaranteed to terminate under two conditions: only finitely many unknowns are encountered, and all right-hand sides are monotonic. While the first condition is unavoidable, the second limits the applicability of the solver. Another limitation is that the solver maintains the current abstract values of all encountered unknowns instead of a minimal set sufficient for performing the iteration. By consuming unnecessarily much space, interprocedural analyses may not succeed on seemingly small programs. In the present paper, we therefore extend the top-down solver TD in three ways. First, we indicate how the restriction to monotonic right-hand sides can be lifted without compromising termination. We then show how the solver can be tuned to store abstract values only when their preservation is inevitable. Finally, we also show how the solver can be extended to side-effecting equation systems. Right-hand sides of these may not only provide values for the corresponding left-hand side unknowns but at the same time produce contributions to other unknowns. This practical extension has successfully been used for a seamless combination of context-sensitive analyses (e.g., of local states) with flow-insensitive analyses (e.g., of globals).","Title: How to Decide Functionality of Compositions of Top-Down Tree Transducers.\nYear: 2022\n\nAbstract: We prove that functionality of compositions of top-down tree transducers is decidable by reducing the problem to the functionality of one top-down tree transducer with look-ahead."],"string":"[\n \"Title: Binary Queries\\nYear: 2002\\n\\nAbstract: Querying XML documents is a basic task for many XML applications. Typically, matches of queries are located individually, i.e. a match is a single node in a queried document. k-ary queries, in contrast, simultaneously identify k locations in the document, which are connected via some specified relation. For example, in rule-based transformations (like XSLT transformations), a node to which a rule is applied and another node which is selected by the rule in the context of the first node could be identified together by a binary query defining the relation between these two nodes. Such a binary query would replace the match and the select pattern used to identify the first and the second node respectively. By eliminating the need for select patterns, binary queries would not only reduce the number of patterns in a transformation, but would also allow that all the pattern matching is done statically, i.e. before the transformation actually begins. We use the formalism of regular forest grammars to define queries of arbitrary arities. Pushdown forest automata have been used in the past to efficiently implement unary queries expressed by using forest grammars. The main contribution of this paper is an algorithm based on pushdown forest automata which evaluates binary queries. In the worst theoretical case the algorithm evaluates binary queries in time proportional to the square of the size of the input document. In practice however, the complexity is mostly rather linear in the input size. Queries for which the right context does not need to be checked can be evaluated even along with the parsing of the input document. Rather than using forest grammars, queries can be also expressed in a more intuitive pattern language using a syntax similar to XPath.\",\n \"Title: Transparent teleteaching\\nYear: 2002\\n\\nAbstract: Today's teleteaching software restricts teaching in the way that it only supports a specific presentation application and a single platform. This is a major drawback and a reason why teleteaching is not that widespread as it could be. Therefore we have created a teleteaching environment, called TeleTeachingTool, which enables lecture recording and transmission to be done transparently to teaching. Our tool allows teachers to use arbitrary software including their preferred presentation tool running on their favorite platform. It combines desktop recording with real-time audio and video streams to a recordable and online presentable lecture. In this paper we will discuss the requirements of teleteaching, describe our teleteaching environment and compare it with other teaching software.\",\n \"Title: Annotiertes Lecture Recording\\nYear: 2004\\n\\nAbstract: Zur Durchführung virtueller Vorlesungen ist es nützlich, neben Ton und Bild auch jeweils den gesamten Desktop aufzuzeichnen und zu übertragen. Dies wird durch die Benutzung von anwendungsunabhängigem Screen-Recording unterstützt. Ebenfalls für Präsentationen bewährt haben sich Annotations- möglichkeiten, die es gestatten, die Aufmerksamkeit zu fokussieren und Vermerke auf einer ansonsten überwiegend statischen Projektionfläche anzubringen. Wir berichten über eine erfolgreiche Kombination von allgemeinem Screen-Recording mit einem einfachen aber flexiblen Annotierungssystem für den gesamten Desktop und zeigen, dass dies die Dynamik der Vorlesungen erhöht.\",\n \"Title: Automatic Complexity Analysis\\nYear: 2002\\n\\nAbstract: We consider the problem of automating the derivation of tight asymptotic complexity bounds for solving Horn clauses. Clearly, the solving time crucially depends on the "sparseness" of the computed relations. Therefore, our asymptotic runtime analysis is accompanied by an asymptotic sparsity calculus together with an asymptotic sparsity analysis. The technical problem here is that least fixpoint iteration fails on asymptotic complexity expressions: the intuitive reason is that O(1)+ O(1) = O(1)...\",\n \"Title: Interprocedural herbrand equalities\\nYear: 2005\\n\\nAbstract: We present an aggressive interprocedural analysis for inferring value equalities which are independent of the concrete interpretation of the operator symbols. These equalities, called Herbrand equalities, are therefore an ideal basis for truly machine-independent optimizations as they hold on every machine. Besides a general correctness theorem, covering arbitrary call-by-value parameters and local and global variables, we also obtain two new completeness results: one by constraining the analysis problem to Herbrand constants, and one by allowing side-effect-free functions only. Thus if we miss a constant/equality in these two scenarios, then there exists a separating interpretation of the operator symbols.\",\n \"Title: Numerical document queries\\nYear: 2003\\n\\nAbstract: A query against a database behind a site like Napster may search, e.g., for all users who have downloaded more jazz titles than pop music titles. In order to express such queries, we extend classical monadic second-order logic by Presburger predicates which pose numerical restrictions on the children (content) of an element node and provide a precise automata-theoretic characterization. While the existential fragment of the resulting logic is decidable, it turns out that satisfiability of the full logic is undecidable. Decidable satisfiability and a querying algorithm even with linear data complexity can be obtained if numerical constraints are only applied to those contents of elements where ordering is irrelevant. Finally, it is sketched how these techniques can be extended also to answer questions like, e.g., whether the total price of the jazz music downloaded so far exceeds a user's budget.\",\n \"Title: Macro forest transducers\\nYear: 2004\\n\\nAbstract: XML documents conceptually are not trees, but forests. Therefore, we extend the concept of macro tree transducers (mtt's) to a transformation formalism of forests, macro forest transducers (mft's). We show that mft's form a strict superset of mtt's operating on forests (represented as binary trees). On the other hand, the transformation of every mft can be simulated by the composition of two mtt's. Although macro forest transducers are more powerful, the complexity of inverse type inference, i.e., computing the pre-image of a recognizable language, is almost the same as for tree transducers.\",\n \"Title: On the Finite Degree of Ambiguity of Finite Tree Automata\\nYear: 1989\\n\\nAbstract: The degree of ambiguity of a finite tree automaton A, da(A), is the maximal number of different accepting computations of A for any possible input tree. We show: it can be decided in polynomial time whether or not da(A)A with n states and rank L>1 having a finite degree of ambiguity: for every input tree t there is a input tree t1 of depth less than 22n·n! having the same number of accepting computations; the degree of ambiguity of A is bounded by 222·log(L+1)·n.\",\n \"Title: A Note on Karr's Algorithm\\nYear: 2004\\n\\nAbstract: We give a simple formulation of Karr's algorithm for computing all affine relationships in affine programs. This simplified algorithm runs in time O(nk(3)) where n is the program size and k is the number of program variables assuming unit cost for arithmetic operations. This improves upon the original formulation by a factor of k. Moreover, our re-formulation avoids exponential growth of the lengths of intermediately occurring numbers (in binary representation) and uses less complicated elementary operations. We also describe a generalization that determines all polynomial relations up to degree d in time O(nk(3d)).\",\n \"Title: Computing polynomial program invariants\\nYear: 2004\\n\\nAbstract: We present two automatic program analyses. The first analysis checks if a given polynomial relation holds among the program variables whenever control reaches a given program point. It fully interprets assignment statements with polynomial expressions on the right-hand side and polynomial disequality guards. Other assignments are treated as non-deterministically assigning any value and guards that are not polynomial disequalities are ignored. The second analysis extends this checking procedure. It computes the set of all polynomial relations of an arbitrary given form that are valid at a given target program point. It is also complete up to the abstraction described above.\",\n \"Title: Analysis of modular arithmetic\\nYear: 2007\\n\\nAbstract: We consider integer arithmetic modulo a power of 2 as providedby mainstream programming languages like Java or standardimplementations of C. The difficulty here is that, for w 1, the ring Zm of integers modulom = 2w has zero divisors and thus cannotbe embedded into a field. Not withstanding that, we present intra-and interprocedural algorithms for inferring for every programpoint u affine relations between program variables valid atu. If conditional branching is replaced withnondeterministic branching, our algorithms are not only sound butalso complete in that they detect all valid affinerelations in a natural class of programs. Moreover, they run intime linear in the program size and polynomial in the number ofprogram variables and can be implemented by using the same modularinteger arithmetic as the target language to be analyzed. We alsoindicate how our analysis can be extended to deal with equalityguards, even in an interprocedural setting.\",\n \"Title: Interprocedural analyses: a comparison\\nYear: 2000\\n\\nAbstract: We present a framework for program analysis of languages with procedures which is general enough to allow for a comparison of various approaches to interprocedural analysis. Our framework is based on a small-step operational semantics and subsumes both frameworks for imperative and for logic languages. We consider reachability analysis, that is, the problem of approximating the sets of program states reaching program points. We use our framework in order to clarify the impact of several independent design decisions on the precision of the analysis. Thus, we compare intraprocedural forward accumulation with intraprocedural backward accumulation. Furthermore, we consider both relational and functional approaches. While for relational analysis the accumulation strategy makes no difference in precision, we prove for functional analysis that forward accumulation may lose precision against backward accumulation. Concerning the relative precision of relational analyses and corresponding functional analyses, we exhibit scenarios where functional analysis does not lose precision. Finally, we explain why even an enhancement of functional analysis through disjunctive completion of the underlying abstract domain may sometimes lose precision against relational analysis.\",\n \"Title: Games through Nested Fixpoints\\nYear: 2009\\n\\nAbstract: In this paper we consider two-player zero-sum payoff games on finite graphs, both in the deterministic as well as in the stochastic setting. In the deterministic setting, we consider total-payoff games which have been introduced as a refinement of mean-payoff games [10, 18]. In the stochastic setting, our class is a turn-based variant of liminf-payoff games [4, 15, 16]. In both settings, we provide a non-trivial characterization of the values through nested fixpoint equations. The characterization of the values of liminf-payoff games moreover shows that solving liminf-payoff games is polynomial-time reducible to solving stochastic parity games. We construct practical algorithms for solving the occurring nested fixpoint equations based on strategy iteration. As a corollary we obtain that solving deterministic total-payoff games and solving stochastic liminf-payoff games is in UP *** co*** UP.\",\n \"Title: Polynomial Constants Are Decidable\\nYear: 2002\\n\\nAbstract: Constant propagation aims at identifying expressions that always yield a unique constant value at run-time. It is well-known that constant propagation is undecidable for programs working on integers even if guards are ignored as in non-deterministic flow graphs. We show that polynomial constants are decidable in non-deterministic flow graphs. In polynomial constant propagation, assignment statements that use the operators +, ,� are interpreted exactly but all assignments that use other operators are conservatively interpreted as non-deterministic as- signments. We present a generic algorithm for constant propagation via a symbolic weakest precondition computation and show how this generic algorithm can be instantiated for polynomial constant propagation by exploiting techniques from computable ring theory.\",\n \"Title: Infinite-State High-Level MSCs: Model-Checking and Realizability\\nYear: 2002\\n\\nAbstract: We consider three natural classes of infinite-state HMSCs: globally-cooperative, locally-cooperative and local-choice HMSCs. We show first that model-checking for globally-cooperative and locally-cooperative HMSCs has the same complexity as for the class of finite-state (bounded) HMSCs. Surprisingly, model-checking local-choice HMSCs turns out to be exponentially more efficient in space than for locally-cooperative HMSCs. We also show that locally-cooperative and local-choice HMSCs can be always implemented by communicating finite states machines, provided we allow some additional (bounded) message data. Moreover, the implementation of local-choice HMSCs is deadlock-free and of linear-size.\",\n \"Title: Locating Matches of Tree Patterns in Forests\\nYear: 1998\\n\\nAbstract: s and 1/TechReports/FullTextVia WWW: URL <a href=\\\"http://citeseer.ist.psu.edu/rd/0/http%3AqSqqSqwww.informatik.uni-trier.deqSqReportsqSqList\\\" onmouseover=\\\"self.status=\\\"http://www.informatik.uni-trier.de/Reports/List\\\"; return true\\\" onmouseout=\\\"self.status=\\\"\\\"; return true\\\">http://www.informatik.uni-trier.de/Reports/List</a>Via email: Send a mail to ftpmail@ftp.informatik.uni-trier.de, subject'MAIL ME CLEAR\\\", body \\\"TechReports.HowTo\\\" followedby an empty line, for detailed instructionsPrinted copies:Trierer ForschungsberichteFachbereich IV -Mathematik / InformatikUniversitat Trier..D-54286 TrierISSN 0944-0488Forschungsbericht Nr. 98--08Locating Matches of Tree Patterns in ForestsAndreas Neumann and Helmut...\",\n \"Title: Parameter-reduction of higher level grammars\\nYear: 1987\\n\\nAbstract: A higher level (OI-) grammar is called terminating if for every accessible term t there is at least one terminal term which can be derived from t . A grammar is called parameter-reduced if it is terminating and has no superfluous parameters. For every grammar G of level n 0 which generates at least one term we construct grammars R( G ) and P( G ) such that R( G ) and P( G ) generate the same language as G but are terminating and parameter-reduced respectively. We introduce a hierarchy of restrictions to the delection capability of the grammars which allow a gradual decrease in the complexity of the algorithms from n -iterated exponential time to polynomial time.\",\n \"Title: Precise relational invariants through strategy iteration\\nYear: 2007\\n\\nAbstract: We present a practical algorithm for computing exact least solutions of systems of equations over the rationals with addition, multiplication with positive constants, minimum and maximum. The algorithm is based on strategy improvement combined with solving linear programming problems for each selected strategy. We apply our technique to compute the abstract least fixpoint semantics of affine programs over the relational template constraint matrix domain [20]. In particular, we thus obtain practical algorithms for computing the abstract least fixpoint semantics over the zone and octagon abstract domain.\",\n \"Title: The Fork95 parallel programming language: design, implementation, application\\nYear: 1997\\n\\nAbstract: Fork95 is an imperative parallel programming language intended to express algorithms for synchronous shared memory machines\\n (PRAMs). It is based on ANSI C and offers additional constructs to hierarchically divide processor groups into subgroups and\\n manage shared and private address subspaces. Fork95 makes the assembly-level synchronicity of the underlying hardware available\\n to the programmer at the language level. Nevertheless, it supports locally asynchronous computation where desired by the programmer.\\n We present a one pass compiler, fcc, which compiles Fork95 and C programs to the SB-PRAM machine. The SB-PRAM is a lock-step\\n synchronous, massively parallel multiprocessor currently being built at Saarbrücken University, with a physically shared memory\\n and uniform memory access time. We examine three important types of parallel computation frequently used for the parallel\\n solution of real-world problems. While farming and parallel divide-and-conquer are directly supported by Fork95 language constructs,\\n pipelining can be easily expressed using existing language features; an additional language construct for pipelining is not\\n required.\",\n \"Title: ForkLight: A Control-Synchronous Parallel Programming Language\\nYear: 1999\\n\\nAbstract: ForkLight is an imperative, task-parallel programming language for massively parallel shared memory machines. It is based on ANSI C, follows the SPMD model of parallel program execution, provides a sequentially consistent shared memory, and supports dynamically nested parallelism. While no assumptions are made on uniformity of memory access time or instruction- level synchronicity of the underlying hardware, ForkLight offers a simple but powerful mecha- nism for coordination of parallel processes in the traditio n and notation of PRAM algorithms: Be- yond its asynchronous default execution mode, ForkLight offers a mode for control-synchronous execution that relates the program's block structure to par allel control flow. We give a scheme for compiling ForkLight to C with calls to a very small set of basic shared memory access operations like atomic fetch&add. This yields portability across parallel archi- tectures and exploits the local optimizations of their nati ve C compilers. Our implementation is publically available; performance results are reported. We also discuss translation to OpenMP. 1. INTRODUCTION. Parallel processing offers an attractive way to increase com- puter performance. MIMD architectures, where program control is individual to each processor, offer high flexibility in programming, but devising, implementing and debug- ging parallel programs is difficult. Even more difficulties arise if the programmer has to care about explicit data distribution to achieve reasonable performan ce. Automatic parallelization and automatic data distribution techniques are still lim ited to rather reg- ular programs. Addressing the latter problem, parallel computer manufactu rers and re- search groups recently devised several types of massively parallel (or at least s calable) machines providing a shared memory. Some of these still require program tuning for locality to perform efficiently, e.g. Stanford DASH (18), while others use multithread- ing to hide the memory access latency and high-bandwidth memory networks, and thus become more or less independent of locality issues, e.g. Tera MTA (2). So far there is only one massively parallel shared memory architecture that of fers uniform memory access time (UMA), the SB-PRAM (1). Due to a common clockall processors of the SB-PRAM work synchronously, i.e. they start (and complete) exe- cution of an instruction simultaneously. This synchronicity makes par allel program- ming very easy, as it leads to deterministic parallel program execution; it i s particularly well suited for the implementation of synchronous algorithms using e.g. fine-grained pipelines or data-parallel operations. Furthermore, such synchronous MI MD machines with UMA shared memory are very popular in theoretical computer science, where they are known as PRAMs (Parallel Random Access Machines). On the other hand, no massively parallel MIMD machine that is commercially avail- able today is UMA or synchronous in this sense. Rather, the following features are common: The user sees a large amount of threads (due to scalable architecture and multithreading) and a monolithic shared memory (due to a hidden network). There is no common clock. The memory access time is non-uniform, but more or less indepen- dent of locality (due to multithreading). Program execution is asynchro nous (due to the\",\n \"Title: Single-valuedness of tree transducers is decidable in polynomial time\\nYear: 1992\\n\\nAbstract: A bottom-up finite-state tree transducer (FST) A is called single-valued iff for every input tree there is at most one output tree. We give a polynomial-time algorithm which decides whether or not a given FST is single-valued. The algorithm is based on: • the freedom of the submonoid of trees which contain at least one occurrence of one variable ∗; • the succinct representation of trees by graphs; • a sequence of normalizing transformations of the given transducer; and • a polynomially decidable characterization of pairs of equivalent output functions. We apply these methods to show that finite-valuedness is decidable in polynomial time as well.\",\n \"Title: Contextual Locking for Dynamic Pushdown Networks.\\nYear: 2013\\n\\nAbstract: Contextual locking is a scheme for synchronizing between possibly recursive processes that has been proposed by Chadha et al. recently. Contextual locking allows for arbitrary usage of locks within the same procedure call and Chadha et al. show that control-point reachability for two processes adhering to contextual locking is decidable in polynomial time. Here, we complement these results. We show that in presence of contextual locking, control-point reachability becomes PSPACE-hard, already if the number of processes is increased to three. On the other hand, we show that PSPACE is both necessary and sufficient for deciding control-point reachability of k processes for k > 2, and that this upper bound remains valid even if dynamic spawning of new processes is allowed. Furthermore, we consider the problem of regular reachability, i.e., whether a configuration within a given regular set can be reached. Here, we show that this problem is decidable for recursive processes with dynamic thread creation and contextual locking. Finally, we generalize this result to processes that additionally use a form of join operations.\",\n \"Title: Precise Interval Analysis vs. Parity Games\\nYear: 2008\\n\\nAbstract: In [8], a practical algorithm for precise interval analysis is provided for which, however, no non-trivial upper complexity bound is known. Here, we present a lower bound by showing that precise interval analysis is at least as hard as computing the sets of winning positions in parity games. Our lower-bound proof relies on an encoding of parity games into systems of particular integer equations. Moreover, we present a simplification of the algorithm for integer systems from [8]. For the given encoding of parity games, the new algorithm provides another algorithm for parity games which is almost as efficient as the discrete strategy improvement algorithm by Vöge and Jurdziński [17].\",\n \"Title: Flat and one-variable clauses: Complexity of verifying cryptographic protocols with single blind copying\\nYear: 2008\\n\\nAbstract: Cryptographic protocols with single blind copying were defined and modeled by Comon and Cortier using the new class C of first-order clauses. They showed its satisfiability problem to be in 3-DEXPTIME. We improve this result by showing that satisfiability for this class is NEXPTIME-complete, using new resolution techniques. We show satisfiability to be DEXPTIME-complete if clauses are Horn, which is what is required for modeling cryptographic protocols. While translation to Horn clauses only gives a DEXPTIME upper bound for the secrecy problem for these protocols, we further show that this secrecy problem is actually DEXPTIME-complete.\",\n \"Title: Least and greatest solutions of equations over N\\nYear: 1996\\n\\nAbstract: We consider the problem of computing least and greatest solutions of a system of equations xi = fi, i = 1,..., n, over N, i.e., the naturals (extended by ∞), where the right hand sides fi are expressions built up from constants and variables by various sets of operations.We present efficient algorithms in case where the following operations occur: (1) minimum and maximum; (2) maximum, addition and multiplication; (3) minimum, addition and multiplication; (4) minimum, maximum, addition and multiplication. We extend the methods to the cases where (one-sided) conditionals are allowed as well.\",\n \"Title: Side-effect analysis of assembly code\\nYear: 2011\\n\\nAbstract: In this paper we present a light-weight interprocedural side-effect analysis on assembly code. We represent the modifying potential of a procedure f by classifying all write accesses, occurring within f, relative to the parameter registers. In particular our approach is the first to accurately handle reference parameters. We demonstrate the usefulness of this approach by integrating this analysis into our assembly analyser and provide an evaluation of the precision of our approach. Approximately 50 per cent of all procedures can be statically shown to have side-effects.\",\n \"Title: Interprocedural Information Flow Analysis of XML Processors.\\nYear: 2014\\n\\nAbstract: A crucial issue when providing publicly accessible web services is that sensitive data should only be accessible by authorized users. Accessibility of data within an application or information flow can conveniently be formalized as a 2-hyperproperty of a program. Here, we present a technique to interprocedurally analyze information flow in XML processors. Our approach is based on general techniques for program matching, and relational abstract interpretation of the resulting 2-programs. In case of XML processors, the abstract relational semantics then can be practically analyzed by means of finite tree automata.\",\n \"Title: Verifying a local generic solver in coq\\nYear: 2010\\n\\nAbstract: Fixpoint engines are the core components of program analysis tools and compilers. If these tools are to be trusted, special attention should be paid also to the correctness of such solvers. In this paper we consider the local generic fixpoint solver RLD which can be applied to constraint systems x ⊇ fx, x ∈ V, over some lattice D where the right-hand sides fx are given as arbitrary functions implemented in some specification language. The verification of this algorithm is challenging, because it uses higher-order functions and relies on side effects to track variable dependences as they are encountered dynamically during fixpoint iterations. Here, we present a correctness proof of this algorithm which has been formalized by means of the interactive proof assistant COQ.\",\n \"Title: Control-Flow Analysis in Cubic Time\\nYear: 2001\\n\\nAbstract: It is well-known that context-independent control flow analysis can be performed in cubic time for functional and object-oriented languages. Yet recent applications of control flow analysis to calculi of computation (like the π-calculus and the ambient calculus) have reported considerably higher complexities. In this paper we introduce two general techniques, the use of Horn clauses with sharing and the use of tiling of Horn clauses, for reducing the worst-case complexity of analyses. Applying these techniques to the π-calculus and the ambient calculus we reduce the complexity from O(n5) to O(n3) in both cases.\",\n \"Title: Precise Analysis Of Value-Dependent Synchronization In Priority Scheduled Programs\\nYear: 2014\\n\\nAbstract: Although priority scheduling in concurrent programs provides a clean way of synchronization, developers still additionally rely on hand-crafted schemes based on integer variables to protect critical sections. We identify a set of sufficient conditions for variables to serve this purpose. We provide efficient methods to verify these conditions, which enable us to construct an enhanced analysis of mutual exclusion in interrupt-driven concurrent programs. All our algorithms are build upon off-the-shelf inter-procedural analyses alone. We have implemented this approach for the analysis of automotive controllers, and demonstrate that it results in a major improvement in the precision of data race detection compared to purely priority-based techniques.\",\n \"Title: Crossing the syntactic barrier: hom-disequalities for H1-clauses\\nYear: 2012\\n\\nAbstract: We extend ${\\\\mathcal H}_1$-clauses with disequalities between images of terms under a tree homomorphism (hom-disequalities). This extension allows to test whether two terms are distinct modulo a semantic interpretation, allowing, e.g., to neglect information that is not considered relevant for the intended comparison. We prove that ${\\\\mathcal H}_1$-clauses with hom-disequalities are more expressive than ${\\\\mathcal H}_1$-clauses with ordinary term disequalities, and that they are incomparable with ${\\\\mathcal H}_1$-clauses with disequalities between paths. Our main result is that ${\\\\mathcal H}_1$-clauses with this new type of constraints can be normalized into an equivalent tree automaton with hom-disequalities. Since emptiness for that class of automata turns out to be decidable, we conclude that satisfiability is decidable for positive Boolean combinations of queries to predicates defined by ${\\\\mathcal H}_1$-clauses with hom-disequalities.\",\n \"Title: Precise fixpoint computation through strategy iteration\\nYear: 2007\\n\\nAbstract: We present a practical algorithm for computing least solutions of systems of equations over the integers with addition, multiplication with positive constants, maximum and minimum. The algorithm is based on strategy iteration. Its run-time (w.r.t. the uniform cost measure) is independent of the sizes of occurring numbers. We apply our technique to solve systems of interval equations. In particular, we show how arbitrary intersections as well as full interval multiplication in interval equations can be dealt with precisely.\",\n \"Title: Minimization of deterministic bottom-up tree transducers\\nYear: 2010\\n\\nAbstract: We show that for every deterministic bottom-up tree transducer, a unique equivalent transducer can be constructed which is minimal. The construction is based on a sequence of normalizing transformations which, among others, guarantee that non-trivial output is produced as early as possible. For a deterministic bottom-up transducer where every state produces either none or infinitely many outputs, the minimal transducer can be constructed in polynomial time.\",\n \"Title: On finitely generated monoids of matrices with entries in N\\nYear: 1991\\n\\nAbstract: Let GAMMA be a nonempty, finite set of square matrices of size n with entries in the semiring N. Consider the matrix-monoid [GRAPHICS] generated by GAMMA. We show: If GAMMA* is finite, then [GRAPHICS] where N = inverted-right-perpendicular e2.n! inverted-left-perpendicular -2. This assertion is false for any N N smaller than 2n-2. If GAMMA has exactly one member and GAMMA* is finite, then [GRAPHICS] (g denotes Landau's function). In the last assertion N is V minimal.\",\n \"Title: Program Analysis through Finite Tree Automata\\nYear: 2009\\n\\nAbstract: Dynamic Pushdown Networks (dpn's) have recently been introduced as a convenient abstraction of systems which provide recursive procedure calls and spawning of concurrent tasks such as Java programs [1, 4-6]. We show how the executions of dpn's can naturally be represented through ranked trees. The configuration reached by a program execution then can be read off from the sequence of leaves of this execution tree. This observation allows us to reduce decision problems such as reachability of configurations within a regular set for dpn's to standard decision problems for finite tree automata.\",\n \"Title: Computing game values for crash games\\nYear: 2007\\n\\nAbstract: We consider crash games which are a generalization of parity games in which the play value of a play is an integer, -∞ or ∞. In particular, the play value of a finite play is given as the sum of the payoffs of the moves of the play. Accordingly, one player aims at maximizing the play value whereas the other player aims at minimizing this value. We show that the game value of such a crash game at position v, i.e., the least upper bounds to the minimal play value that can be enforced by the maximum player in a play starting at v, can be characterized by a hierarchical system of simple integer equations. Moreover, we present a practical algorithm for solving such systems. The run-time of our algorithm (w.r.t. the uniform cost measure) is independent of the sizes of occurring numbers. Our method is based on a strategy improvement algorithm. The efficiency of our algorithm is comparable to the efficiency of the discrete strategy improvement algorithm developed by Vöge and Jurdzinski for the simpler Boolean case of parity games [19].\",\n \"Title: Enriched MU-Calculi Module Checking\\nYear: 2008\\n\\nAbstract: The model checking problem for open finite-state systems (called module checking) has been intensively studied in the literature with respect to CTL and CTL*. In this paper, we focus on module checking with respect to the fully enriched mu-calculus and some of its fragments. Fully enriched p-calculus is the extension of the propositional p-calculus with inverse programs, graded modalities, and nominals. The fragments we consider here are obtained by dropping at least one of the additional constructs. For the full calculus, we show that module checking is undecidable by using a reduction from the domino problem. For its fragments, instead, we show that module checking is decidable and EXPTIME-complete. This result is obtained by using, for the upper bound, a classical automata-theoretic approach via Forest Enriched Automata and, for the lower bound, a reduction from the module checking problem for CTL, known to be EXPTIME-hard.\",\n \"Title: Extending H1-clauses with disequalities\\nYear: 2011\\n\\nAbstract: The class H\\\"1 has proven particularly useful for the analysis of term-manipulating programs such as cryptographic protocols. Here, we show that clauses from that class can be extended with disequalities between arbitrary terms while retaining decidability of satisfiability. The proof is based on a normalization procedure together with a procedure to decide whether a finite automaton with disequalities accepts less than k elements, and a subtle combinatorial argument to prove that only finitely many disequalities need to be considered.\",\n \"Title: Relational abstract interpretation for the verification of 2-hypersafety properties\\nYear: 2013\\n\\nAbstract: Information flow properties of programs can be formalized as hyperproperties specifying the relation of multiple executions. In this paper, we therefore introduce a framework for proving 2-hypersafety properties by means of abstract interpretation. The main idea is to apply abstract interpretation on the self-compositions of the control flow graphs of programs. As a result, our method is inherently capable of analyzing relational properties of even dissimilar programs. Constructing self-compositions of control flow graphs is nontrivial. Therefore, we present an algorithm for constructing quality self-compositions driven by a tree distance measure between the abstract syntax trees of subprograms. Finally, we demonstrate the applicability of the approach by proving intricate information flow properties of programs written in a simple language for tree manipulation motivated by the Web Services Business Process Execution Language.\",\n \"Title: Interprocedurally analysing linear inequality relations\\nYear: 2007\\n\\nAbstract: In this paper we present an alternative approach to interprocedurally inferring linear inequality relations. We propose an abstraction of the effects of procedures through convex sets of transition matrices. In the absence of conditional branching, this abstraction can be characterised precisely by means of the least solution of a constraint system. In order to handle conditionals, we introduce auxiliary variables and postpone checking them until after the procedure calls. In order to obtain an effective analysis, we approximate convex sets by means of polyhedra. Since our implementation of function composition uses the frame representation of polyhedra, we rely on the subclass of simplices to obtain an efficient implementation. We show that for this abstraction the basic operations can be implemented in polynomial time. First practical experiments indicate that the resulting analysis is quite efficient and provides reasonably precise results.\",\n \"Title: Integer Constraints to Stop Deforestation\\nYear: 1996\\n\\nAbstract: . Deforestation is a transformation of functional programs toremove intermediate data structures. It is based on outermost unfoldingof function calls where folding occurs when unfolding takes placewithin the same nested function call. Since unrestricted unfolding mayencounter arbitrarily many terms, a termination analysis has to determinethose subterms where unfolding is possibly dangerous. We showthat such an analysis can be obtained from a control flow analysis by anextension...\",\n \"Title: On the complexity of equational horn clauses\\nYear: 2005\\n\\nAbstract: Security protocols employing cryptographic primitives with algebraic properties are conveniently modeled using Horn clauses modulo equational theories. We consider clauses corresponding to the class $\\\\mathcal{H}3$ of Nielson, Nielson and Seidl. We show that modulo the theory ACU of an associative-commutative symbol with unit, as well as its variants like the theory XOR and the theory AG of Abelian groups, unsatisfiability is NP-complete. Also membership and intersection-non-emptiness problems for the closely related class of one-way as well as two-way tree automata modulo these equational theories are NP-complete. A key technical tool is a linear time construction of an existential Presburger formula corresponding to the Parikh image of a context-free language. Our algorithms require deterministic polynomial time using an oracle for existential Presburger formulas, suggesting efficient implementations are possible.\",\n \"Title: On the degree of ambiguity of finite automata\\nYear: 1986\\n\\nAbstract: We investigate the ambiguity behavior of finite automata in connection with their inner structure. We show that the degree of ambiguity of a finitely ambiguous nondeterministic finite automaton (NFA) with n states is at most 5 n 2 · n n . There is a simple criterion which characterizes the infinite degree of ambiguity of an NFA, and which is decidable in polynomial time. The degree of growth of the ambiguity of an NFA is computable in polynomial time. Starting from the first result, we discuss the maximal finite degree of ambiguity of an NFA with n states, and we present subclasses of NFAs where this quantity is of order 2 Θ( n ) .\",\n \"Title: Look-Ahead Removal for Top-Down Tree Transducers.\\nYear: 2013\\n\\nAbstract: Top-down tree transducers are a convenient formalism for describing tree transformations. They can be equipped with regular look-ahead, which allows them to inspect a subtree before processing it. In certain cases, such a look-ahead can be avoided and the transformation can be realized by a transducer without look-ahead. Removing the look-ahead from a transducer, if possible, is technically highly challenging. For a restricted class of transducers with look-ahead, namely those that are total, deterministic, ultralinear, and bounded erasing, we present an algorithm that, for a given transducer from that class, (1) decides whether it is equivalent to a total deterministic transducer without look-ahead, and (2) constructs such a transducer if the answer is positive. For the whole class of total deterministic transducers with look-ahead we present a similar algorithm, which assumes that a so-called difference bound is known for the given transducer. The designer of a transducer can usually also determine a difference bound for it.\",\n \"Title: Binary queries for document trees\\nYear: 2004\\n\\nAbstract: Motivated by XML applications, we address the problem of answering k-ary queries, i.e. simultaneously locating k nodes of an input tree as specified by a given relation. In particular, we discuss how binary queries can be used as a means of navigation in XML document transformations. We introduce a grammar-based approach to specifying k-ary queries. An efficient tree-automata based implementation of unary queries is reviewed and the extensions needed in order to implement k-ary queries are presented. In particular, an efficient solution for the evaluation of binary queries is provided and proven correct. We introduce fxgrep, a practical implementation of unary and binary queries for XML. By means of fxgrep and of the fxt XML transformation language we suggest how binary queries can be used in order to increase expressivity of rule-based transformations. We compare our work with other querying languages and discuss how our ideas can be used for other existing settings.\",\n \"Title: A faster solver for general systems of equations\\nYear: 1999\\n\\nAbstract: We present a new algorithm which computes a partial approximate solution for a system of equations. It is local in that it considers just as many variables as necessary in order to compute the values of those variables we are interested in, it is generic in that it makes no assumptions on the application domain, and it is general in that the algorithm does not depend on any specific properties of right-hand sides of equations. For instance, monotonicity is not required. However, in case the right-hand sides satisfy some weak monotonicity property, our algorithm returns the (uniquely defined) least solution. The algorithm meets the best theoretical worstcase complexity known for similar algorithms. For the application of analyzing logic languages, it also gives the best practical results on most of our real-world benchmark programs.\",\n \"Title: Abstract interpretation meets convex optimization\\nYear: 2012\\n\\nAbstract: Numerical static program analyses by abstract interpretation, e.g., the problem of inferring bounds for the values of numerical program variables, are faced with the problem that the abstract domains often contain infinite ascending chains. In order to enforce termination within the abstract interpretation framework, a widening/narrowing approach can be applied that trades the guarantee of termination against a potential loss of precision. Alternatively, recently strategy improvement algorithms have been proposed for computing numerical invariants which do not suffer the imprecision incurred by widenings. Before, strategy improvement algorithms have successfully been applied for solving two-players zero-sum games. In this article we discuss and compare max-strategy and min-strategy improvement algorithms for static program analysis. For that, the algorithms are cast within a common general framework of solving systems of fixpoint equations x-=e where the right-hand sides e are maxima of finitely many monotone and concave functions. Then we indicate how the general setting can be instantiated for inferring numerical invariants of programs based on non-linear templates.\",\n \"Title: A succinct solver for ALFP\\nYear: 2002\\n\\nAbstract: We develop a solver algorithm which allows to efficiently compute the stable model of a very expressive fragment of predicate logic. The succinct formulation of the algorithm is due to the disciplined use of continuations and memoisation. This facilitates giving a precise characterisation of the behaviour of the solver and to develop a complexity calculation which allows to obtain its formal complexity. Practical experiments on a control-flow analysis of the ambient calculus show that the solver frequently performs better than the worst-case complexity estimates.\",\n \"Title: Cryptographic Analysis in Cubic Time\\nYear: 2001\\n\\nAbstract: The spi-calculus is a variant of the polyadic π-calculus that admits symmetric cryptography and that admits expressing communication protocols in a precise though still abstract way. This paper shows that context-independent control flow analysis can be calculated in cubic time despite the fact that the spi-calculus operates over an infinite universe of values. Our approach is based on Horn Clauses with Sharing and we develop transformations to pass from the infinite to the finite and to deal with the polyadic nature of input and output. We prove that this suffices for obtaining a cubic time implementation without sacrificing precision and without making simplifying assumptions on the nature of keys.\",\n \"Title: Counting in Trees for Free\\nYear: 2004\\n\\nAbstract: it is known that MSO logic for ordered unranked trees is undecidable if Presburger constraints are allowed at children of nodes. We show here that a decidable logic is obtained if we use a modal fixpoint logic instead. We present a characterization of this logic by means of deterministic Presburger tree automata and show how it can be used to express numerical document queries. Surprisingly, the complexity of satisfiability for the extended logic is asymptotically the same as for the original fixpoint logic. The non-emptiness for Presburger tree automata (PTA) is PSPACE-complete, which is moderate given that it is already PSPACE-hard to test whether the complement of a regular expression is non-empty. We also identify a subclass of PTAs with a tractable non-emptiness problem. Further, to decide whether a tree t satisfies a formula phi is polynomial in the size of phi and linear in the size of t. A technical construction of independent interest is a linear time construction of a Presburger formula for the Parikh image of a regular language.\",\n \"Title: Earliest Normal Form And Minimization For Bottom-Up Tree Transducers\\nYear: 2011\\n\\nAbstract: We show that for every deterministic bottom-up tree transducer, a unique equivalent transducer can be constructed which is minimal. The construction is based on a sequence of normalizing transformations which, among others, guarantee that non-trivial output is produced as early as possible. For a deterministic bottom-up transducer where every state produces either none or infinitely many outputs, the minimal transducer can be constructed in polynomial time.\",\n \"Title: Numerical Invariants through Convex Relaxation and Max-Strategy Iteration\\nYear: 2014\\n\\nAbstract: We present an algorithm for computing the uniquely determined least fixpoints of self-maps on (with ) that are point-wise maximums of finitely many monotone and order-concave self-maps. This natural problem occurs in the context of systems analysis and verification. As an example application we discuss how our method can be used to compute template-based quadratic invariants for linear systems with guards. The focus of this article, however, lies on the discussion of the underlying theory and the properties of the algorithm itself.\",\n \"Title: Solving systems of rational equations through strategy iteration\\nYear: 2011\\n\\nAbstract: We present practical algorithms for computing exact least solutions of equation systems over the reals with addition, multiplication by positive constants, minimum and maximum. The algorithms are based on strategy iteration. Our algorithms can, for instance, be used for the analysis of recursive stochastic games. In the present article we apply our techniques for computing abstract least fixpoint semantics of affine programs over the relational template polyhedra domain. In particular, we thus obtain practical algorithms for computing abstract least fixpoint semantics over the abstract domains of intervals, zones, and octagons.\",\n \"Title: On optimal slicing of parallel programs\\nYear: 2001\\n\\nAbstract: Optimal program slicing determines for a statement S in a program &pgr; whether or not S affects a specified set of statements, given that all conditionals in &pgr; are interpreted as non-deterministic choices.Only recently, it has been shown that reachability of program points and hence also optimal slicing is undecidable for multi-threaded programs with (parameterless) procedures and synchronization [23]. Here, we sharpen this result by proving that slicing remains undecidable if synchronization is abandoned---although reachability becomes polynomial. Moreover, we show for multi-threaded programs without synchronization, that slicing stays PSPACE-hard when procedure calls are forbidden, and becomes NP-hard for loop-free programs. Since the latter two problems can be solved in PSPACE and NP, respectively, even in presence of synchronization, our new lower bounds are tight.Finally, we show that the above decidability and lower bound properties equally apply to other simple program analysis problems like copy constant propagation and true liveness of variables. This should be contrasted to the problems of strong copy constant propagation and (ordinary) liveness of variables for which polynomial algorithms have been designed [15, 14, 24].\",\n \"Title: A quadratic regularity test for non-deleting macro S grammars\\nYear: 1985\\n\\nAbstract: A quadratic regularity test is presented for non-deleting simple deterministic contextfree tree grammars as well as for non-deleting macro S grammars.\",\n \"Title: Region Analysis for Race Detection\\nYear: 2009\\n\\nAbstract: Automatic race detection of C programs requires fast, yet sufficiently precise analysis of dynamic memory. Therefore, we present\\n a region-based pointer analysis which seeks to identify disjoint regions of dynamically allocated objects to ensure that write accesses to the same region are always protected by the same mutexes.\\n Our approach has been implemented within the interprocedural analyzer of concurrent C programs GobLint and we have successfully\\n applied it on code from the Linux kernel, such as the access vector cache. This code relies on a synchronized hash table where\\n an array of doubly linked lists is protected by an array of locks.\",\n \"Title: On distributive fixed-point expressions\\nYear: 1999\\n\\nAbstract: For every fixed-point expression e of alternation-depth r, we construct a new fixed-point expression e' of alternation-depth 2 and size O(r . \\\\e\\\\). Expression e' is equivalent to e whenever operators are distributive and the underlying complete lattice has a co-continuous least upper bound. We show that our transformation is optimal not only w.r.t. alternation-depth but also w.r.t. the increase in size of the resulting expression. AMS Subject Classification. 68Q60, 03D70, 06D99, 68Q25.\",\n \"Title: Normalization of linear horn clauses\\nYear: 2010\\n\\nAbstract: Nielson et al. [12] exhibit a rich class of Horn clauses which they call H1. Least models of finite sets of H1 Horn clauses are regular tree languages. Nielson et al. [12] describe a normalization procedure for computing least models of finite sets of H1 Horn clauses in the form of tree automata. In the present paper, we simplify and extend this normalization procedure to a semi-procedure that deals with finite sets of linear Horn clauses. The extended semi-procedure does not terminate in general but does so on useful subclasses of finite sets of linear Horn clauses. The extension in particular coincides with the normalization procedure of Nielson et al. [12] for sets of H1 Horn clauses. In order to demonstrate the usefulness of the extension, we show how backward reachability analysis for constrained dynamic pushdown networks (see Bouajjani et al. [3]) can be encoded into a class of finite sets of linear Horn clauses for which our normalization procedure terminates after at most exponentially many steps.\",\n \"Title: Fast interprocedural linear two-variable equalities\\nYear: 2011\\n\\nAbstract: In this article we provide an interprocedural analysis of linear two-variable equalities. The novel algorithm has a worst-case complexity of 𝒪(n ⋅ k4), where k is the number of variables and n is the program size. Thus, it saves a factor of k4 in comparison to a related algorithm based on full linear algebra. We also indicate how the practical runtime can be further reduced significantly. The analysis can be applied, for example, for register coalescing, for identifying local variables and thus for interprocedurally observing stack pointer modifications as well as for an analysis of array index expressions, when analyzing low-level code.\",\n \"Title: Polynomial Precise Interval Analysis Revisited\\nYear: 2009\\n\\nAbstract: We consider a class of arithmetic equations over the complete lattice of integers (extended with -驴 and 驴) and provide a polynomial time algorithm for computing least solutions. For systems of equations with addition and least upper bounds, this algorithm is a smooth generalization of the Bellman-Ford algorithm for computing the single source shortest path in presence of positive and negative edge weights. The method then is extended to deal with more general forms of operations as well as minima with constants. For the latter, a controlled widening is applied at loops where unbounded increase occurs. We apply this algorithm to construct a cubic time algorithm for the class of interval equations using least upper bounds, addition, intersection with constant intervals as well as multiplication.\",\n \"Title: Join-lock-sensitive forward reachability analysis for concurrent programs with dynamic process creation\\nYear: 2011\\n\\nAbstract: Dynamic Pushdown Networks (DPNs) are a model for parallel programs with (recursive) procedures and dynamic process creation. Constraints on the sequences of spawned processes allow to extend the basic model with joining of created processes [2]. Orthogonally DPNs can be extended with nested locking [9]. Reachability of a regular set R of configurations in presence of stable constraints as well as reachability without constraints but with nested locking are based on computing the set of predecessors pre* (R). In the present paper, we present a forward-propagating algorithm for deciding reachability for DPNs. We represent sets of executions by sets of execution trees and show that the set of all execution trees resulting in configurations from R which either allow a lock-sensitive execution or a join-sensitive execution, is regular. Here, we rely on basic results about macro tree transducers. As a second contribution, we show that reachability is decidable also for DPNs with both nested locking and joins.\",\n \"Title: Shape analysis of low-level c with overlapping structures\\nYear: 2010\\n\\nAbstract: Device drivers often keep data in multiple data structures simultaneously while embedding list or tree related records into the records containing the actual data; this results in overlapping structures. Shape analyses have traditionally relied on a graph-based representation of memory where a node corresponds to a whole record and edges to pointers. As this is ill-suited for encoding overlapping structures, we propose and formally relate two refined memory models. We demonstrate the appropriateness of these models by implementing shape analyses based on them within the TVLA framework. The implementation is exemplified using code extracted from cache managing kernel modules.\",\n \"Title: Synchronized Tree Languages Revisited and New Applications\\nYear: 2001\\n\\nAbstract: We present a new formulation for tree-tuple synchronized languages, much simpler than the existing one. This new formulation allows us to prove stronger structural results. As a consequence, synchronized languages give rise to new applications : - to rewriting : given tree languages L1 (synchronized), L2 (regular), Rel(L1) ⊆ L2 is decidable for several rewrite-like relations Rel. - to concurrency : we prove decidability of the logic EF for a process calculus allowing some bounded form of communication. Consequently, the absence of deadlocks is decidable.\",\n \"Title: How to combine widening and narrowing for non-monotonic systems of equations\\nYear: 2013\\n\\nAbstract: Non-trivial analysis problems require complete lattices with infinite ascending and descending chains. In order to compute reasonably precise post-fixpoints of the resulting systems of equations, Cousot and Cousot have suggested accelerated fixpoint iteration by means of widening and narrowing. The strict separation into phases, however, may unnecessarily give up precision that cannot be recovered later. While widening is also applicable if equations are non-monotonic, this is no longer the case for narrowing. A narrowing iteration to improve a given post-fixpoint, additionally, must assume that all right-hand sides are monotonic. The latter assumption, though, is not met in presence of widening. It is also not met by equation systems corresponding to context-sensitive interprocedural analysis, possibly combining context-sensitive analysis of local information with flow-insensitive analysis of globals. As a remedy, we present a novel operator that combines a given widening operator with a given narrowing operator. We present adapted versions of round-robin as well as of worklist iteration, local, and side-effecting solving algorithms for the combined operator and prove that the resulting solvers always return sound results and are guaranteed to terminate for monotonic systems whenever only finitely many unknowns (constraint variables) are encountered.\",\n \"Title: A Smooth Combination of Linear and Herbrand Equalities for Polynomial Time Must-Alias Analysis\\nYear: 2009\\n\\nAbstract: We present a new domain for analyzing must -equalities between address expressions. The domain is a smooth combination of Herbrand and affine equalities which enables us to describe field accesses and array indexing. While the full combination of uninterpreted functions with affine arithmetics results in intractable assertion checking algorithms, our restricted domain allows us to construct an analysis of address must -equalities that runs in polynomial time. We indicate how this analysis can be applied to infer access patterns in programs manipulating arrays and structs.\",\n \"Title: Weakly Regular Relations and Applications\\nYear: 2001\\n\\nAbstract: A new class of tree-tuple languages is introduced: the weakly regular relations. It is an extension of the regular case (regular relations) and a restriction of tree-tuple synchronized languages, that has all usual nice properties, except closure under complement. Two applications are presented: to unification modulo a rewrite system, and to one-step rewriting.\",\n \"Title: Bottom-up tree automata with term constraints\\nYear: 2010\\n\\nAbstract: We introduce bottom-up tree automata with equality and disequality term constraints. These constraints are more expressive than the equality and disequality constraints between brothers introduced by Bogaert and Tison in 1992. Our new class of automata is still closed under Boolean operations. Moreover, we show that for tree automata with term constraints not only membership but also emptiness is decidable. This contrasts with the undecidability of emptiness for automata with arbitrary equality constraints between subterms identified by paths as shown in 1981 by Mongy.\",\n \"Title: A Modal Mu-Calculus for Durational Transition Systems\\nYear: 1996\\n\\nAbstract: Durational transition systems are finite transition systems where every transition is additionally equipped with a duration. We consider the problem of interpreting $\\\\mu$--formulas over durational transition systems. In case the formula contains only operations minimum, maximum, addition, and sequencing, we show that the interpretation ist not only computable but (up to a linear factor) as efficiently computable as the interpretation of $\\\\mu$--formulas over ordinary finite transition systems.\",\n \"Title: Characterizing Complexity Classes by Higher Type Primitive Recursive Definitions, Part II\\nYear: 1990\\n\\nAbstract: Higher type primitive recursive definitions (also known as Gödel's system T) defining first-order functions (i.e. functions of type ind→...→ind→ind, ind for individuals, higher types occur in between) can be classified into an infinite syntactic hierarchy: A definition is in the n'th stage of this hierarchy, a so called rank-n-definition, iff n is an upper bound on the levels of the types occurring in it.\",\n \"Title: Normalizable Horn Clauses, Strongly Recognizable Relations, and Spi\\nYear: 2002\\n\\nAbstract: We exhibit a rich class of Horn clauses, which we call H1, whose least models, though possibly infinite, can be computed effectively. We show that the least model of an H1 clause consists of so-called strongly recognizable relations and present an exponential normalization procedure to compute it. In order to obtain a practical tool for program analysis, we identify a restriction of H1 clauses, which we call H2, where the least models can be computed in polynomial time. This fragment still allows to express, e.g., Cartesian product and transitive closure of relations. Inside H2, we exhibit a fragment H3 where normalization is even cubic. We demonstrate the usefulness of our approach by deriving a cubic control-flow analysis for the Spi calculus [1] as presented in [14].\",\n \"Title: Finite tree automata with cost functions\\nYear: 1994\\n\\nAbstract: Cost functions for tree automata are mappings from transitions to (tuples of) polynomials over some semiring. We consider four semirings, namely, N the semiring of nonnegative integers, A the ''arctical semiring'', T the tropical semiring and F the semiring of finite subsets of nonnegative integers. We show: for semirings N and A it is decidable in polynomial time whether or not the costs of accepting computations is bounded; for F it is decidable in polynomial time whether or not the cardinalities of occurring cost sets are bounded. In all three cases, we derive explicit upper bounds. For semiring T, we prove decidability of boundedness as well, but obtain a polynomial-time algorithm only in case that the degrees of occurring polynomials are at most 1.\",\n \"Title: What is a pure functional?\\nYear: 2010\\n\\nAbstract: Given an ML function f : (int → int) → int how can we rigorously specify that f is pure, i.e., produces no side-effects other than those arising from calling its functional argument? We show that existing methods based on preservation of invariants and relational parametricity are insufficient for this purpose and thus define a new notion that captures purity in the sense that for any functional F that is pure in this sense there exists a corresponding question-answer strategy. This research is motivated by an attempt to prove algorithms correct that take such supposedly pure functionals as input and apply them to stateful arguments in order to inspect intensional aspects of their behaviour.\",\n \"Title: Upper adjoints for fast inter-procedural variable equalities\\nYear: 2008\\n\\nAbstract: We present a polynomial-time algorithm which at the extra cost of a factor O(k) (k the number of variables) generalizes inter-procedural copy constant propagation. Our algorithm infers variable-variable equalities in addition to equalities between variables and constants. Like copy constant propagation, it tracks constant and copying assignments but abstracts more complex assignments and guards. The algorithm is based on the observation that, for the abstract lattice of consistent equivalence relations, the upper adjoints of summary functions can be represented much more succinctly than summary functions themselves.\",\n \"Title: Flat and One-Variable Clauses for Single Blind Copying Protocols: The XOR Case\\nYear: 2009\\n\\nAbstract: In cryptographic protocols with the single blind copying restriction, at most one piece of unknown data is allowed to be copied in each step of the protocol. The secrecy problem for such protocols can be modeled as the satisfiability problem for the class of first-order Horn clauses called flat and one-variable Horn clauses, and is known to be DEXPTIME-complete. We show that when an XOR operator is additionally present, then the secrecy problem is decidable in 3-EXPTIME. We also note that replacing XOR by the theory of associativity-commutativity or by the theory of Abelian groups, or removing some of the syntactic restrictions on the clauses, leads to undecidability.\",\n \"Title: Tree automata for code selection\\nYear: 1991\\n\\nAbstract: We deal with the generation of code selectors in compiler backends. The fundamental concepts are systematically derived from the theory of regular tree grammars and finite tree automata. We use this general approach to construct algorithms that generalize and improve existing methods.\",\n \"Title: Cryptographic protocol verification using tractable classes of horn clauses\\nYear: 2006\\n\\nAbstract: We consider secrecy problems for cryptographic protocols modeled using Horn clauses and present general classes of Horn clauses which can be efficiently decided. Besides simplifying the methods for the class of flat and one-variable clauses introduced for modeling of protocols with single blind copying [7,25], we also generalize this class by considering k-variable clauses instead of one-variable clauses with suitable restrictions similar to those for the class S+. This class allows to conveniently model protocols with joint blind copying. We show that for a fixed k, our new class can be decided in DEXPTIME, as in the case of one variable.\",\n \"Title: Deciding equivalence of top--down XML transformations in polynomial time\\nYear: 2009\\n\\nAbstract: Many useful XML transformations can be expressed by deterministic top-down tree transducers. A normal form is presented for such transducers (extended with the facility to inspect their input trees). A transducer in normal form has a unique canonical form which can be obtained by a minimization procedure, in polynomial time. Thus, equivalence of transducers in normal form can be decided in polynomial time. If the transducer is total, the normal form can be obtained in polynomial time as well.\",\n \"Title: A Type-safe Macro System for XML\\nYear: 2002\\n\\nAbstract: XML is originally designed for the use in document processing. Every classical document processing system supports a mechanism which is called macro. In general, a macro is a named collection of actions. These actions are executed whenever the name of the macro appears in a document instance. We describe a very small but powerful macro language for XML. The presented language supports macros with arguments. As a main result we will show that for a macro expansion H and a recognizable set R the set H-1(R) of trees t, whose macro expansion H(t) are in R, is recognizable. This implies that the typechecking problem for macro expansion is decidable. A major drawback of this approach is the time complexity. Therefore we designed a practical typechecking discipline. We equip every macro definition with a type expression describing the input forests. On the basis of this type information the macro processor computes an output type for the macro. Having inferred this output type, we aim at extending the given output DTD to a DTD for admissible input possibly containing unexpanded macros.\",\n \"Title: Tree Transducers and Formal Methods (Dagstuhl Seminar 13192).\\nYear: 2013\\n\\nAbstract: The aim of this Dagstuhl Seminar was to bring together researchers from various research areas related to the theory and application of tree transducers. Recently, interest in tree transducers has been revived due to surprising new applications in areas such as XML databases, security verification, programming language theory, and linguistics. This seminar therefore aimed to inspire the exchange of theoretical results and information regarding the practical requirements related to tree transducers.\",\n \"Title: Constraint-Based Inter-Procedural Analysis of Parallel Programs\\nYear: 2000\\n\\nAbstract: We provide a uniform framework for the analysis of programs with procedures and explicit, unbounded, fork/join parallelism covering not only bitvector problems like reaching definitions or live variables but also non-bitvector problems like simple constant propagation. Due to their structural similarity to the sequential case, the resulting algorithms are as efficient as their widely accepted sequential counterparts, and they can easily be integrated in existing program analysis environments like e.g. METAFRAME or PAG. We are therefore convinced that our method will soon find its way into industrial-scale computer systems.\",\n \"Title: Runtime enforcement of information flow security in tree manipulating processes\\nYear: 2012\\n\\nAbstract: We consider the problem of enforcing information flow policies in Xml manipulating programs such as Web services and business processes implemented in current workflow languages. We propose a runtime monitor that can enforce the secrecy of freely chosen subtrees of the data throughout the execution. The key idea is to apply a generalized constant propagation for computing the public effect of branching constructs whose conditions may depend on the secret. This allows for a better precision than runtime monitors which rely on tainting of variables or nodes alone. We demonstrate our approach for a minimalistic tree manipulating programming language and prove its correctness w.r.t. the concrete semantics of programs.\",\n \"Title: Propagating differences: an efficient new fixpoint algorithm for distributive constraint systems\\nYear: 1998\\n\\nAbstract: Integrating semi-naive fixpoint iteration from deductive data bases [3, 2, 4] as well as continuations into worklist-based solvers, we derive a new application independent local fixpoint algorithm for distributive constraint systems. Seemingly different efficient algorithms for abstract interpretation like those for linear constant propagation for imperative languages [16] as well as for control-flow analysis for functional languages [12] turn out to be instances of our scheme. Besides this systematizing contribution we also derive a new efficient algorithm for abstract OLDT-resolution as considered in [14, 15, 24] for Prolog.\",\n \"Title: Formalising the pi-calculus using nominal logic\\nYear: 2009\\n\\nAbstract: We formalise the pi-calculus using the nominal datatype package, a package based on ideas from the nominal logic by Pitts et al., and demonstrate an implementation in Isabelle/HOL. The purpose is to derive powerful induction rules for the semantics in order to conduct machine checkable proofs, closely following the intuitive arguments found in manual proofs. In this way we have covered many of the standard theorems of bisimulation equivalence and congruence, both late and early, and both strong and weak in a unison manner. We thus provide one of the most extensive formalisations of a process calculus ever done inside a theorem prover. A significant gain in our formulation is that agents are identified up to alpha-equivalence, thereby greatly reducing the arguments about bound names. This is a normal strategy for manual proofs about the pi-calculus, but that kind of hand waving has previously been difficult to incorporate smoothly in an interactive theorem prover. We show how the nominal logic formalism and its support in Isabelle accomplishes this and thus significantly reduces the tedium of conducting completely formal proofs. This improves on previous work using weak higher order abstract syntax since we do not need extra assumptions to filter out exotic terms and can keep all arguments within a familiar first-order logic.\",\n \"Title: Computing relaxed abstract semantics w.r.t. quadratic zones precisely\\nYear: 2010\\n\\nAbstract: In the present paper we compute numerical invariants of programs by abstract interpretation. For that we consider the abstract domain of quadratic zones recently introduced byAdjé et al. [2]. We use a relaxed abstract semantics which is at least as precise as the relaxed abstract semantics of Adjé et al. [2]. For computing our relaxed abstract semantics, we present a practical strategy improvement algorithm for precisely computing least solutions of fixpoint equation systems, whose right-hand sides use order-concave operators and the maximum operator. These fixpoint equation systems strictly generalize the fixpoint equation systems considered by Gawlitza and Seidl [11].\",\n \"Title: Model checking information flow in reactive systems\\nYear: 2012\\n\\nAbstract: Most analysis methods for information flow properties do not consider temporal restrictions. In practice, however, such properties rarely occur statically, but have to consider constraints such as when and under which conditions a variable has to be kept secret. In this paper, we propose a natural integration of information flow properties into linear-time temporal logics (LTL). We add a new modal operator, the hide operator, expressing that the observable behavior of a system is independent of the valuations of a secret variable. We provide a complexity analysis for the model checking problem of the resulting logic SecLTL and we identify an expressive fragment for which this question is efficiently decidable. We also show that the path based nature of the hide operator allows for seamless integration into branching time logics.\",\n \"Title: When Is a Functional Tree Transduction Deterministic?\\nYear: 1993\\n\\nAbstract: We give a decision procedure to determine whether or not the transduction of a functional transducer can be realized by a deterministic (resp. reduced deterministic) transducer. In case this is possible we exhibit a general construction to build this transducer.\",\n \"Title: Approximative Methods for Monotone Systems of Min-Max-Polynomial Equations\\nYear: 2008\\n\\nAbstract: On the Internet, there are advertisements (ads) of different kinds: image, text, video and other specially marked objects that are distinct from the underlying content of the page. There is an industry behind the management of such ads, and they face ...\",\n \"Title: An Even Faster Solver for General Systems of Equations\\nYear: 1996\\n\\nAbstract: . We present a new algorithm which computes a partial approximatesolution for a system of equations. It is local in that it considersas few variables as necessary in order to compute the values of thosevariables we are interested in, it is generic in that it makes no assumptionson the application domain, and it is general in that the algorithmdoes not depend on any specific properties of right-hand sides of equations.For instance, monotonicity is not required. However, in case the...\",\n \"Title: Efficiently intertwining widening and narrowing.\\nYear: 2015\\n\\nAbstract: A warrowing operator is constructed which combines widening and narrowing.Variations of standard fixpoint algorithms are equipped with the new operator.For the resulting solvers, termination is proven under liberal assumptions.Experiments indicate that precision may be increased significantly at a decent cost. Accelerated fixpoint iteration by means of widening and narrowing is the method of choice for solving systems of equations over domains with infinite ascending chains. The strict separation into an ascending widening and a descending narrowing phase, however, may unnecessarily give up precision that cannot be recovered later. It is also unsuitable for equation systems with infinitely many unknowns - where local solving must be used.As a remedy, we present a novel operator ¿ that combines a given widening operator ¿ with a given narrowing operator Δ. We present adapted versions of round-robin and worklist iteration as well as local and side-effecting solving algorithms for the combined operator ¿. We prove that the resulting solvers always return sound results and are guaranteed to terminate for monotonic systems whenever only finitely many unknowns are encountered.\",\n \"Title: Parametric Strategy Iteration.\\nYear: 2014\\n\\nAbstract: Program behavior may depend on parameters, which are either configured before compilation time, or provided at run-time, e.g., by sensors or other input devices. Parametric program analysis explores how different parameter settings may affect the program behavior. In order to infer invariants depending on parameters, we introduce parametric strategy iteration. This algorithm determines the precise least solution of systems of integer equations depending on surplus parameters. Conceptually, our algorithm performs ordinary strategy iteration on the given integer system for all possible parameter settings in parallel. This is made possible by means of region trees to represent the occurring piecewise affine functions. We indicate that each required operation on these trees is polynomial-time if only constantly many parameters are involved. Parametric strategy iteration for systems of integer equations allows to construct parametric integer interval analysis as well as parametric analysis of differences of integer variables. It thus provides a general technique to realize precise parametric program analysis if numerical properties of integer variables are of concern.\",\n \"Title: Inter-procedural Two-Variable Herbrand Equalities.\\nYear: 2014\\n\\nAbstract: We prove that all valid Herbrand equalities can be inter-procedurally inferred for programs where all assignments whose right-hand sides depend on at most one variable are taken into account. The analysis is based on procedure summaries representing the weakest pre-conditions for finitely many generic post-conditions with template variables. In order to arrive at effective representations for all occurring weakest pre-conditions, we show for almost all values possibly computed at run-time, that they can be uniquely factorized into tree patterns and a ground term. Moreover, we introduce an approximate notion of subsumption which is effectively decidable and ensures that finite conjunctions of equalities may not grow infinitely. Based on these technical results, we realize an effective fixpoint iteration to infer all inter-procedurally valid Herbrand equalities for these programs. Finally we show that an invariant candidate with a constant number of variables, can be verified in polynomial time.\",\n \"Title: Language support for synchronous parallel critical sections\\nYear: 1995\\n\\nAbstract: We introduce a new parallel programming paradigm, namely synchronous parallel critical sections. Such parallel critical sections must be seen in the context of switching between synchronous and asynchronous modes of computation. Thread farming allows to generate bunches of threads to solve independent subproblems asynchronously and in parallel. Opposed to that, synchronous parallel critical sections allow to organize bunches of asynchronous parallel threads to execute certain tasks jointly and synchronously. We show how the PRAM language Fork95 can be extended by a construct \\\"join\\\" supporting parallel critical sections. We explain its semantics and implementation, and discuss possible applications.\",\n \"Title: Enhancing Top-Down Solving with Widening and Narrowing.\\nYear: 2016\\n\\nAbstract: We present an enhancement of the generic fixpoint algorithm TD which can deal with widening and narrowing even for non-monotonic systems of equations. In contrast to corresponding enhancements proposed for other standard fixpoint algorithms, no extra priorities on variables are required. Still, a mechanism can be devised so that occurrences of the widening/narrowing operator are inserted as well as removed dynamically.\",\n \"Title: An Analysis of Universal Information Flow Based on Self-Composition\\nYear: 2015\\n\\nAbstract: We introduce a novel way of proving information flow properties of a program based on its self-composition. Similarly to the universal information flow type system of Hunt and Sands, our analysis explicitly computes the dependencies of variables in the final state on variables in the initial state. Accordingly, the analysis result is independent of specific information flow lattices, and allows to derive information flow w.r.t. any of these. While our analysis runs in polynomial time, we prove that it never loses precision against the type system of Hunt and Sands, and may gain extra precision by taking similarities between different branches of conditionals into account. Also, we indicate how it can be smoothly generalized to an interprocedural analysis.\",\n \"Title: Equivalence of Deterministic Top-Down Tree-to-String Transducers is Decidable.\\nYear: 2015\\n\\nAbstract: We show that equivalence of deterministic top-down tree-to-string transducers is decidable, thus solving a long standing open problem in formal language theory. We also present efficient algorithms for subclasses: polynomial time for total transducers with unary output alphabet (over a given top-down regular domain language), and co-randomized polynomial time for linear transducers, these results are obtained using techniques from multi-linear algebra. For our main result, we prove that equivalence can be certified by means of inductive invariants using polynomial ideals. This allows us to construct two semi-algorithms, one searching for a proof of equivalence, one for a witness of non-equivalence.\",\n \"Title: Enforcing Termination of Interprocedural Analysis.\\nYear: 2016\\n\\nAbstract: Interprocedural analysis by means of partial tabulation of summary functions may not terminate when the same procedure is analyzed for infinitely many abstract calling contexts or when the abstract domain has infinite strictly ascending chains. As a remedy, we present a novel local solver for general abstract equation systems, be they monotonic or not, and prove that this solver fails to terminate only when infinitely many variables are encountered. We clarify in which sense the computed results are sound. Moreover, we show that interprocedural analysis performed by this novel local solver, is guaranteed to terminate for all non-recursive programs—irrespective of whether the complete lattice is infinite or has infinite strictly ascending or descending chains.\",\n \"Title: Static race detection for device drivers: the Goblint approach.\\nYear: 2016\\n\\nAbstract: Device drivers rely on fine-grained locking to ensure safe access to shared data structures. For human testers, concurrency makes such code notoriously hard to debug; for automated reasoning, dynamically allocated memory and low-level pointer manipulation poses significant challenges. We present a flexible approach to data race analysis, implemented in the open source Goblint static analysis framework, that combines different pointer and value analyses in order to handle a wide range of locking idioms, including locks allocated dynamically as well as locks stored in arrays. To the best of our knowledge, this is the most ambitious effort, having lasted well over ten years, to create a fully automated static race detection tool that can deal with most of the intricate locking schemes found in Linux device drivers. Our evaluation shows that these analyses are sufficiently precise, but practical use of these techniques requires inferring environmental and domain-specific assumptions.\",\n \"Title: Reachability For Dynamic Parametric Processes\\nYear: 2017\\n\\nAbstract: In a dynamic parametric process every subprocess may spawn arbitrarily many, identical child processes, that may communicate either over global variables, or over local variables that are shared with their parent. We show that reachability for dynamic parametric processes is decidable under mild assumptions. These assumptions are e.g. met if individual processes are realized by pushdown systems, or even higher-order pushdown systems. We also provide algorithms for subclasses of pushdown dynamic parametric processes, with complexity ranging between NP and DEXPTIME.\",\n \"Title: Specifying and Verifying Secrecy in Workflows with Arbitrarily Many Agents.\\nYear: 2016\\n\\nAbstract: Web-based workflow management systems, like EasyChair, HealthVault, Ebay, or Amazon, often deal with confidential information such as the identity of reviewers, health data, or credit card numbers. Because the number of participants in the workflow is in principle unbounded, it is difficult to describe the information flow policy of such systems in specification languages that are limited to a fixed number of agents. We introduce a first-order version of HyperLTL, which allows us to express information flow requirements in workflows with arbitrarily many agents. We present a bounded model checking technique that reduces the violation of the information flow policy to the satisfiability of a first-order formula. We furthermore identify conditions under which the resulting satisfiability problem is guaranteed to be decidable.\",\n \"Title: Computing the longest common prefix of a context-free language in polynomial time.\\nYear: 2018\\n\\nAbstract: We present two structural results concerning the longest common prefixes of non-empty languages. First, we show that the longest common prefix of the language generated by a context-free grammar of size N equals the longest common prefix of the same grammar where the heights of the derivation trees are bounded by 4N. Second, we show that each non-empty language L has a representative subset of at most three elements which behaves like L w.r.t. the longest common prefix as well as w.r.t. longest common prefixes of L after unions or concatenations with arbitrary other languages. From that, we conclude that the longest common prefix, and thus the longest common suffix, of a context-free language can be computed in polynomial time.\",\n \"Title: Verifying Security Policies in Multi-agent Workflows with Loops.\\nYear: 2017\\n\\nAbstract: We consider the automatic verification of information flow security policies of web-based workflows, such as conference submission systems like EasyChair. Our workflow description language allows for loops, non-deterministic choice, and an unbounded number of participating agents. The information flow policies are specified in a temporal logic for hyperproperties. We show that the verification problem can be reduced to the satisfiability of a formula of first-order linear-time temporal logic, and provide decidability results for relevant classes of workflows and specifications. We report on experimental results obtained with an implementation of our approach on a series of benchmarks.\",\n \"Title: Formal Methods of Transformations (Dagstuhl Seminar 17142).\\nYear: 2017\\n\\nAbstract: The goal of this Dagstuhl seminar was to gather researchers working on the theory and practice of transformations (also know as transductions) of word and tree structures, which are realised by transducers (automata with outputs). This seminar was motivated by recent advances and breakthrough results, both in the settings of words and trees.\",\n \"Title: Balancedness of MSO transductions in polynomial time.\\nYear: 2018\\n\\nAbstract: We show that MSO definable tree-to-string transductions with a fixed copy number, given as top-down tree-to-string transducers with fixed copying-bound, can be checked for balancedness of all output strings in polynomial time. We also present an upper bound for the copying bound for deterministic top-down transducers and show that in general, balancedness of output languages of deterministic finite-copying top-down tree-to-string transducers is DExptime-hard.\",\n \"Title: Inductive Invariants for Noninterference in Multi-agent Workflows\\nYear: 2018\\n\\nAbstract: Our goal is to certify absence of information leaks in multi-agent workflows, such as conference management systems like EasyChair. These workflows can be executed by any number of agents some of which may form coalitions against the system. Therefore, checking noninterference is a challenging problem. Our paper offers two main contributions: First, a technique is provided to translate noninterference (in presence of various agent capabilities and declassification conditions) into universally quantified invariants of an instrumented new workflow program. Second, general techniques are developed for checking and inferring universally quantified inductive invariants for workflow programs. In particular, a large class of workflows is identified where inductiveness of invariants is decidable, as well as a smaller, still useful class of workflows where the weakest inductive universal invariant implying the desired invariant, is effectively computable. The new algorithms are implemented and applied to certify noninterference for workflows arising from conference management systems.\",\n \"Title: Least Solutions of Equations over N\\nYear: 1994\\n\\nAbstract: We consider the problem of computing the least solution X\\n\\ni\\n, i=1,..., n, of a system of equations x\\ni=f\\ni, i=1,..., n, over N, i.e., the naturals (extended by ), where the right hand sides f\\ni are expressions built up from constants and variables by operations taken from some set . We present efficient algorithms for various subsets of the operations minimum, maximum, addition and multiplication.\",\n \"Title: Exact XML type checking in polynomial time\\nYear: 2007\\n\\nAbstract: Stay macro tree transducers (smtts) are an expressive formalism for reasoning about XSLT-like document transformations. Here, we consider the exact type checking problem for smtts. While the problem is decidable, the involved technique of inverse type inference is known to have exponential worst-case complexity (already for top-down transformations without parameters). We present a new adaptive type checking algorithm based on forward type inference through exact characterizations of output languages. The new algorithm correctly type-checks all call-by-value smtts. Given that the output type is specified by a deterministic automaton, the algorithm is polynomial-time whenever the transducer uses only few parameters and visits every input node only constantly often. Our new approach can also be generalized from smtts to stay macro forest transducers which additionally support concatenation as built-in output operation.\",\n \"Title: Checking herbrand equalities and beyond\\nYear: 2005\\n\\nAbstract: A Herbrand equality between expressions in a program is an equality which holds relative to the Herbrand interpretation of operators. We show that the problem of checking validity of positive Boolean combinations of Herbrand equalities at a given program point is decidable – even in presence of disequality guards. This result vastly extends the reach of classical methods for global value numbering which cannot deal with disjunctions and are always based on an abstraction of conditional branching with non-deterministic choice. In order to introduce our analysis technique in a simpler scenario we also give an alternative proof that in the classic setting, where all guards are ignored, conjunctions of Herbrand equalities can be checked in polynomial time. As an application of our method, we show how to derive all valid Herbrand constants in programs with disequality guards. Finally, we present a PSPACE lower bound and show that in presence of equality guards instead of disequality guards, it is undecidable to check whether a given Herbrand equality holds or not.\",\n \"Title: Proving Absence of Starvation by Means of Abstract Interpretation and Model Checking.\\nYear: 2017\\n\\nAbstract: The Avionics Application Software Standard Interface ARINC 653 is meant to increase predictability of safety-critical software systems. It allows to coordinate multiple tasks by means of priorities, semaphores, setting and waiting for events as well as by sending suspend and resume signals. Thus, it is a major challenge to verify that no such tightly coupled task gets ultimately stuck, e.g., by infinitely waiting for an event or a resume signal by another task. We explain how abstract interpretation together with model checking may nicely cooperate to guarantee absence of such concurrency flaws and report on practical experiments.\",\n \"Title: Deciding Equivalence of Separated Non-nested Attribute Systems in Polynomial Time.\\nYear: 2019\\n\\nAbstract: In 1982, Courcelle and Franchi-Zannettacci showed that the equivalence problem of separated non-nested attribute systems can be reduced to the equivalence problem of total deterministic separated basic macro tree transducers. They also gave a procedure for deciding equivalence of transducer in the latter class. Here, we reconsider this equivalence problem. We present a new alternative decision procedure and prove that it runs in polynomial time. We also consider extensions of this result to partial transducers and to the case where parameters of transducers accumulate strings instead of trees.\",\n \"Title: Improving Thread-Modular Abstract Interpretation\\nYear: 2021\\n\\nAbstract: We give thread-modular non-relational value analyses as abstractions of a local trace semantics. The semantics as well as the analyses are formulated by means of global invariants and side-effecting constraint systems. We show that a generalization of the analysis provided by the static analyzer GOBLINT as well as a natural improvement of Antoine Mine's approach can be obtained as instances of this general scheme. We show that these two analyses are incomparable w.r.t. precision and provide a refinement which improves on both precision-wise. We also report on a preliminary experimental comparison of the given analyses on a meaningful suite of benchmarks.\",\n \"Title: On The Balancedness Of Tree-To-Word Transducers\\nYear: 2021\\n\\nAbstract: A language over an alphabet B= A boolean OR (A) over bar of opening (A) and closing ((A) over bar) brackets, is balanced if it is a subset of the Dyck language D-B over B, and it is well-formed if all words are prefixes of words in D-B. We show that well-formedness of a context-free language is decidable in polynomial time, and that the longest common reduced suffix can be computed in polynomial time. With this at a hand we decide for the class 2-TW of non-linear tree transducers with output alphabet B whether or not the output language is balanced.\",\n \"Title: Three improvements to the top-down solver\\nYear: 2021\\n\\nAbstract: The local solver TD is a generic fixpoint engine which explores a given system of equations on demand. It has been successfully applied to the interprocedural analysis of procedural languages. The solver TD gains efficiency by detecting dependencies between unknowns on the fly. This algorithm has been recently extended to deal with widening and narrowing as well. In particular, it has been equipped with an automatic detection of widening and narrowing points. That version, however, is only guaranteed to terminate under two conditions: only finitely many unknowns are encountered, and all right-hand sides are monotonic. While the first condition is unavoidable, the second limits the applicability of the solver. Another limitation is that the solver maintains the current abstract values of all encountered unknowns instead of a minimal set sufficient for performing the iteration. By consuming unnecessarily much space, interprocedural analyses may not succeed on seemingly small programs. In the present paper, we therefore extend the top-down solver TD in three ways. First, we indicate how the restriction to monotonic right-hand sides can be lifted without compromising termination. We then show how the solver can be tuned to store abstract values only when their preservation is inevitable. Finally, we also show how the solver can be extended to side-effecting equation systems. Right-hand sides of these may not only provide values for the corresponding left-hand side unknowns but at the same time produce contributions to other unknowns. This practical extension has successfully been used for a seamless combination of context-sensitive analyses (e.g., of local states) with flow-insensitive analyses (e.g., of globals).\",\n \"Title: How to Decide Functionality of Compositions of Top-Down Tree Transducers.\\nYear: 2022\\n\\nAbstract: We prove that functionality of compositions of top-down tree transducers is decidable by reducing the problem to the functionality of one top-down tree transducer with look-ahead.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":113,"string":"113"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":42,"string":"42"}}},{"rowIdx":43,"cells":{"question_id":{"kind":"string","value":"Mo Chen"},"question":{"kind":"string","value":"Generate an abstract for the title \"Contract design for frequency regulation by aggregations of commercial buildings\" using the following items: 1. Contract design problem\n2. Energy aggregator \n3. Commercial buildings \n4. Bilevel optimization \n5. Linear program."},"answer":{"kind":"string","value":"We investigate the contract design problem that an energy aggregator who participates in the wholesale market for Ancillary Services faces. Specifically, we consider a situation in which commercial buildings agree to adjust their heating, ventilation and air conditioning power consumption with respect to a nominal schedule, according to a signal sent by the aggregator. This signal may vary arbitrarily within a certain band, whose (time-varying) width is part of the agreed-upon contract between aggregator and building. In return, the aggregator offers monetary rewards to incentivize the individual buildings. This allows the aggregator to bundle the resulting capacities from different buildings and sell the total capacity in the spot market for frequency regulation. The aggregator's problem is to jointly determine nominal schedules, regulation capacities and monetary rewards to maximize its profit, while ensuring that the individual buildings have an incentive to participate. Assuming that there is no private information, we cast the contract design problem as a bilevel optimization problem, which we in turn reformulate as a mixed-integer program. We further show that if the building does not impose negative externalities on the aggregator, the problem reduces to a Linear Program."},"correct_answer":{"kind":"string","value":"We investigate the contract design problem that an energy aggregator who participates in the wholesale market for Ancillary Services faces. Specifically, we consider a situation in which commercial buildings agree to adjust their heating, ventilation and air conditioning power consumption with respect to a nominal schedule, according to a signal sent by the aggregator. This signal may vary arbitrarily within a certain band, whose (time-varying) width is part of the agreed-upon contract between aggregator and building. In return, the aggregator offers monetary rewards to incentivize the individual buildings. This allows the aggregator to bundle the resulting capacities from different buildings and sell the total capacity in the spot market for frequency regulation. The aggregator's problem is to jointly determine nominal schedules, regulation capacities and monetary rewards to maximize its profit, while ensuring that the individual buildings have an incentive to participate. Assuming that there is no private information, we cast the contract design problem as a bilevel optimization problem, which we in turn reformulate as a mixed-integer program. We further show that if the building does not impose negative externalities on the aggregator, the problem reduces to a Linear Program."},"documents":{"kind":"list like","value":["Title: Progressive cut\nYear: 2006\n\nAbstract: Recently, interactive image cutout technique becomes prevalent for image segmentation problem due to its easy-to-use nature. However, most existing stroke-based interactive object cutout system did not consider the user intention inherent in the user interaction process. Strokes in sequential steps are treated as a collection rather than a process, and only the color information of the additional stroke is used to update the color model in the graph cut framework. Accordingly, unexpected fluctuation effect may occur during the process of interactive object cutout. In fact, each step of user interaction reflects the user's evaluation of previous result and his/her intention. By analyzing the user's intention behind the interaction, we propose a progressive cut algorithm, which explicitly models the user's intention into a graph cut framework for the object cutout task. Three aspects of user intention are utilized: 1) the color of the stroke indicates the kind of change s/he expects, 2) the location of the stroke indicates the region of interest, 3) the relative position between the stroke and the previous result indicates the segmentation error. By incorporating such information into the cutout system, the new algorithm removes the unexpected fluctuation effect of existing stroke-based graph-cut methods, and thus provides the user a more controllable result with fewer strokes and faster visual feedback. Experiments and user study show the strength of progressive cut in accuracy, speed, controllability, and user experience.","Title: Directed graph embedding\nYear: 2007\n\nAbstract: In this paper, we propose the Directed Graph Embedding (DGE) method that embeds vertices on a directed graph into a vector space by considering the link structure of graphs. The basic idea is to preserve the locality property of vertices on a directed graph in the embedded space. We use the transition probability together with the stationary distribution of Markov random walks to measure such locality property. It turns out that by exploring the directed links of the graph using random walks, we can get an optimal embedding on the vector space that preserves the local affinity which is inherent in the directed graph. Experiments on both synthetic data and real-world Web page data are considered. The application of our method to Web page classification problems gets a significant improvement comparing with state-of-art methods.","Title: Qualitative assessment of intrinsic mode functions of empirical mode decomposition\nYear: 2008\n\nAbstract: The 'empirical mode decomposition' (EMD) method has been recently proposed to deal with nonlinear and non- stationary data, which decomposes signals into 'well-behaved' intrinsic mode functions (IMFs). An assessment on the qualitative performance of the EMD method in terms of the degree of signal nature preservation of individual IMF is provided. This is archived by means of the recently proposed signal characterisation method, based upon examining the signal predicability in phase space. It is shown that the first IMF always performs best in terms of signal nature preserving. Simulation results on both linear and nonlinear benchmark signals support the analysis.","Title: A Novel Channel Assignment Algorithm for Multicast in Multi-radio Wireless Mesh Networks\nYear: 2007\n\nAbstract: With the development of Internet, many new applications with obvious multicast character come forth and become popular, which increase the importance of multicast in Internet especially in wireless access networks where the bandwidths of networks are very limited. In this paper, we consider the problem of channel assignment for multicast in multi-radio wireless mesh networks (WMNs), which have not been studied up to now. We propose a novel channel assignment strategy called UCAS based on unidirectional link model, and give an efficient greedy vertex coloring algorithm called BFVC. Finally, the results of simulations demonstrate the efficiency of the algorithms presented in this paper.","Title: A Novel Tool for Sequential Fusion of Nonlinear Features: A Sleep Psychology Application\nYear: 2006\n\nAbstract: A framework for automated scoring of sleep stages during afternoon naps of healthy humans is introduced. This is achieved by sequential fusion of nonlinear features extracted from three physiological channels: the electroencephalogram (EEG), electrooculogram (EOG) and respiratory trace (RES). These features are generated by means of the recently introduced \"delay vector variance\" (DVV) method which examines local predictability of a signal in phase space. The analysis is accompanied by a set of comprehensive simulations, supporting the approach","Title: An automated vision system for container-code recognition\nYear: 2012\n\nAbstract: Automatic container-code recognition is of great importance to the modern container management system. Similar techniques have been proposed for vehicle license plate recognition in past decades. Compared with license plate recognition, automatic container-code recognition faces more challenges due to the severity of nonuniform illumination and invalidation of color information. In this paper, a computer vision based container-code recognition technique is proposed. The system consists of three function modules, namely location, isolation, and character recognition. In location module, we propose a text-line region location algorithm, which takes into account the characteristics of single character as well as the spatial relationship between successive characters. This module locates the text-line regions by using a horizontal high-pass filter and scanline analysis. To resolve nonuniform illumination, a two-step procedure is applied to segment container-code characters, and a projection process is adopted to isolate characters in the isolation module. In character recognition module, the character recognition is achieved by classifying the extracted features, which represent the character image, with trained support vector machines (SVMs). The experimental results demonstrate the efficiency and effectiveness of the proposed technique for practical usage.","Title: Icruiser: An Improved Approach For Concurrent Heap Buffer Overflow Monitoring\nYear: 2014\n\nAbstract: Heap buffer overflow has been extensively studied for many years, but it remains a severe threat to software security. Previous solutions suffer from limitations in that: 1) Some methods need to modify the target programs; 2) Most methods could impose considerable performance overhead. In this paper, we present iCruiser, an efficient heap buffer overflow monitoring system that uses the multi-core technology. Our system is compatible with existing programs, and it can detect the heap buffer overflows concurrently. Compared with the latest heap protection systems, our approach can achieves stronger security guarantees. Experiments show that iCruiser can detect heap buffer overflow attacks effectively with a little performance overhead.","Title: Real-time motion effect enhancement based on fluid dynamics in figure animation\nYear: 2011\n\nAbstract: In fast figure animation, motion blur is often employed to generate fantastic effects of figure motion, for exaggerating the atmosphere one wants to convey. In the previous works for long time, the solution based on certain kind of image blending in terms of hardware or software, was simply adopted. In order to provide high standard of motion blur effect, methods based on 3D geometry of the motion figure with global illumination become gradually in demand. However, the computation cost to meet such demand is very high and it is hard to achieve real time rendering. In our work, a novel 3D geometric approach of real-time motion effect is proposed. By the approach, a special effect along the motion trajectory based on fluid simulation is combined with the volumetric motion blur. Besides, in order to avoid the redundant calculation of each frame and break the limitation of trajectory generation, we decompose the motion trajectory and employ multi-pass geometry rendering to achieve geometry instancing for reuse. In the pipeline, we separate motion tracking and fluid solution, to support various fluid effects flexibly. As our algorithm is constructed in the context of GPU geometry shading in parallel, high efficiency of computation is guaranteed while realizing gorgeous rendering. As a result, real time rendering including the motion blur effect is achieved.","Title: Efficient Shellcode Detection On Commodity Hardware\nYear: 2013\n\nAbstract: As more and more software vulnerabilities are exposed, shellcode has become very popular in recent years. It is widely used by attackers to exploit vulnerabilities and then hijack program's execution. Previous solutions suffer from limitations in that: 1) Some methods based on static analysis may fail to detect the shellcode using obfuscation techniques. 2) Other methods based on dynamic analysis could impose considerable performance overhead. In this paper, we propose Lemo, an efficient shellcode detection system. Our system is compatible with commodity hardware and operating systems, which enables deployment. To improve the performance of our system, we make use of the multi-core technology. The experiments show that our system can detect shellcode efficiently.","Title: Moving K-Nearest Neighbor Query over Obstructed Regions\nYear: 2010\n\nAbstract: In recent years, there has been a growing need for location-based services (LBS), ranging from resource tracking to personal life assistance. The Moving k Nearest Neighbor (MkNN) query is a main problem in the LBS area, which retrieves the top k nearest neighbors while the query consumer moves. Considerable attention is attracted to this query type and a large number of studies are proposed recently. Most of these studies focus on ideal Euclidean plane where any two points are visible. In this paper, we propose a method to process MkNN queries in areas with obstacles, which is more realistic. We propose the obstacle-free safe region (OSR) concept within which a query point has the same kNN. No additional processing is required when the query consumer moves inside one OSR. Several novel properties are also introduced and employed in our efficient MkNN processing algorithm. Our experimental results show that our approach handles the MkNN queries with high accuracy and works efficiently.","Title: Evaluating probabilistic spatial-range closest pairs queries over uncertain objects\nYear: 2011\n\nAbstract: In emerging applications such as location-based service (LBS), the values of spatial database items are naturally uncertain. This paper focuses on the problem of finding probabilistic closest pairs between two uncertain spatial datasets in a given range, namely, probabilistic spatialrange closest pair (PSRCP) query. In particular, given two uncertain spatial datasets which contain uncertain objects modeled by a set of sampled instances, a PSRCP query retrieves the pairs that satisfy the query with probabilities higher than a given threshold. Several pruning strategies are proposed to filter the objects that cannot constitute an answer, which can significantly improve the query performance. Extensive experiments are performed to examine the effectiveness of our methods.","Title: Exploiting nonlinearity in adaptive signal processing\nYear: 2007\n\nAbstract: Quantitative performance criteria for the analysis of machine learning architectures and algorithms have been long established. However, the qualitative performance criteria, e.g., nonlinearity assessment, are still emerging. To that end, we employ some recent developments in signal characterisation and derive criteria for the assessment of the changes in the nature of the processed signal. In addition, we also propose a novel online method for tracking the system nonlinearity. A comprehensive set of simulations in both the linear and nonlinear settings and their combination supports the analysis.","Title: Progressive Cut: An Image Cutout Algorithm that Models User Intentions\nYear: 2007\n\nAbstract: To give users more control over image segmentation and extraction, we propose the progressive-cut algorithm, which explicitly models the user's intention in a graph-cut framework. Because we incorporate three aspects of user intention into an object cutout system, our algorithm lets users work with fewer strokes, achieving faster and more accurate visual feedback.","Title: Spatial query processing in road networks for wireless data broadcast\nYear: 2013\n\nAbstract: Recently, wireless broadcast environments have attracted significant attention due to its high scalability to broadcast information to a large number of mobile subscribers. It is especially a promising and desirable dissemination method for the heavily loaded environment where a great number of the same type of requests are sent from the users. There have been many studies on processing spatial queries via broadcast model recently. However, not much attention is paid to the spatial queries in road networks on wireless broadcast environments. In this paper, we focus on three common types of spatial queries, namely, k nearest neighbor (kNN) queries, range queries and reverse nearest neighbor (RNN) queries in spatial networks for wireless data broadcast. Specially, we propose a novel index for spatial queries in wireless broadcast environments (ISW). With the reasonable organization and the effectively pre-computed bounds, ISW provides a powerful framework for spatial queries. Furthermore, efficient algorithms are designed to cope with kNN, range and RNN queries separately based on ISW. The search space can be obviously reduced and subsequently the client can download as less as possible data for query processing, which can conserve the energy while not significantly influence the efficiency. The detailed theory analysis of cost model and the experimental results are presented for verifying the efficiency and effectiveness of ISW and our methods.","Title: A practical system of keyphrase extraction for web pages\nYear: 2005\n\nAbstract: Keyphrases can be used to facilitate Web users grasping the main topic(s) of a Web page. We present a practical system of automatic keyphrase extraction for Web pages. In this system, a regression model was first trained based on a set of human-labeled documents. Then it was used to extract keyphrases from new pages automatically. This paper makes three contributions. First, the structure information in a Web page was investigated for keyphrase extraction task. Second, the query log data associated with a Web page collected by a search engine server were used to help keyphrase extraction. Third, a method was put forward in this paper in order to evaluate the similarity of phrases.","Title: Joint optimization of product family configuration and scaling design by Stackelberg game.\nYear: 2014\n\nAbstract: •Currently module configuration and scaling design are treated as two separate decisions.•A significant finding that these two problems are coupled in nature, leading to joint optimization.•A novel application of Stackelberg game models to the product family design field.•Synthesis of unique context of product families within a coherent equilibrium decision framework.•Comparative study reveals that our bilevel model is advantageous over the existing practice.","Title: Sensor noise camera identification: countering counter-forensics\nYear: 2010\n\nAbstract: In camera identification using sensor noise, the camera that took a given image can be determined with high certainty by establishing the presence of the camera's sensor fingerprint in the image. In this paper, we develop methods to reveal counter-forensic activities in which an attacker estimates the camera fingerprint from a set of images and pastes it onto an image from a different camera with the intent to introduce a false alarm and, in doing so, frame an innocent victim. We start by classifying different scenarios based on the sophistication of the attacker's activity and the means available to her and to the victim, who wishes to defend herself. The key observation is that at least some of the images that were used by the attacker to estimate the fake fingerprint will likely be available to the victim as well. We describe the so-called \"triangle test\" that helps the victim reveal attacker's malicious activity with high certainty under a wide range of conditions. This test is then extended to the case when none of the images that the attacker used to create the fake fingerprint are available to the victim but the victim has at least two forged images to analyze. We demonstrate the test's performance experimentally and investigate its limitations. The conclusion that can be made from this study is that planting a sensor fingerprint in an image without leaving a trace is significantly more difficult than previously thought.","Title: An assessment of qualitative performance of machine learning architectures: modular feedback networks.\nYear: 2008\n\nAbstract: A framework for the assessment of qualitative performance of machine learning architectures is proposed. For generality, the analysis is provided for the modular nonlinear pipelined recurrent neural network (PRNN) architecture. This is supported by a sensitivity analysis, which is achieved based upon the prediction performance with respect to changes in the nature of the processed signal and by utilizing the recently introduced delay vector variance (DVV) method for phase space signal characterization. Comprehensive simulations combining the quantitative and qualitative analysis on both linear and nonlinear signals suggest that better quantitative prediction performance may need to be traded in order to preserve the nature of the processed signal, especially where the signal nature is of primary importance (biomedical applications).","Title: An online method for detecting nonlinearity within a signal\nYear: 2006\n\nAbstract: A novel method for online analysis of the changes in signal modality is proposed. This is achieved by tracking the dynamics of the mixing parameter within a hybrid filter rather than the actual filter performance. An implementation of the proposed hybrid filter using a combination of the Least Mean Square (LMS) and the Generalised Normalised Gradient Descent (GNGD) algorithms is analysed and the potential of such a scheme for tracking signal nonlinearity is highlighted. Simulations on linear and nonlinear signals in a prediction configuration support the analysis. Biological applications of the approach have been illustrated on EEG data of epileptic patients.","Title: Fusion of state space and frequency-domain features for improved microsleep detection\nYear: 2005\n\nAbstract: A novel approach for Microsleep Event detection is presented. This is achieved based on multisensor electroencephalogram (EEG) and electrooculogram (EOG) measurements recorded during an overnight driving simulation task. First, using video clips of the driving, clear Microsleep (MSE) and Non-Microsleep (NMSE) events were identified. Next, segments of EEG and EOG of the selected events were analyzed and features were extracted using Power Spectral Density and Delay Vector Variance. The so obtained features are used in several combinations for MSE detection and classification by means of populations of Learning Vector Quantization (LVQ) networks. Best classification results, with test errors down to 13%, were obtained by a combination of all the recorded EEG and EOG channels, all features, and with feature relevance adaptation using Genetic Algorithms.","Title: Isoperimetric cut on a directed graph\nYear: 2010\n\nAbstract: In this paper, we propose a novel probabilistic view of the spectral clustering algorithm. In our framework, the spectral clustering algorithm can be viewed as assigning class labels to samples to minimize the Bayes classification error rate by using a kernel density estimator (KDE). From this perspective, we propose to construct directed graphs using variable bandwidth KDEs. Such a variable bandwidth KDE based directed graph has the advantage that it encodes the local density information of the data in the graph edge weights. In order to cluster vertices of the directed graph, we develop a directed graph partitioning algorithm which optimizes a random walk isoperimetric ratio. The partitioning result can be obtained efficiently by solving a system of linear equations. We have applied our algorithm to several benchmark data sets and obtained promising results.","Title: On Nonlinear Modular Neural Filters\nYear: 2005\n\nAbstract: An assessment of the performance of the pipelined recurrent neural network (PRNN) is provided from two aspects, a quantitative one based on the prediction gain and a qualitative one based on examining the changes in the nature of the processed signal. This is achieved by means of the recently introduced 'Delay Vector Variance' (DVV) method for phase space signal characterisation. A comprehensive analysis of this approach on both linear and nonlinear benchmark signals suggests that the PRNN not only outperforms a single recurrent neural network (RNN) in terms of the prediction gain but also has better or similar performance in terms of preserving the nature of the processed signal.","Title: Feature Fusion for the Detection of Microsleep Events\nYear: 2007\n\nAbstract: A combination of linear and nonlinear methods for feature fusion is introduced and the performance of this methodology is illustrated on a real-world problem: the detection of sudden and non-anticipated lapses of attention in car drivers due to drowsiness. To achieve this, signals coming from heterogeneous sources are processed, namely the brain electric activity, variation in the pupil size, and eye and eyelid movements. For all the signals considered, the features are extracted both in the spectral domain and in state space. Linear features are obtained by the modified periodogram, whereas the nonlinear features are based on the recently introduced method of delay vector variance (DVV). The decision process based on such fused features is achieved by support vector machines (SVM) and learning vector quantization (LVQ) neural networks. For the latter also methods of metrics adaptation in the input space are applied. The parameters of all utilized algorithms are optimized empirically in order to gain maximal classification accuracy. It is also shown that metrics adaptation by weighting the input features can improve the classification accuracy, but only to a limited extent. Limited improvements are also obtained when fusing features of selected signals, but highest improvements are gained by fusion of features of all available signals. In this case test errors are reduced down to 9% in the mean, which clearly illustrates the potential of our methodology to establish a reference standard of drowsiness and microsleep detection devices for future online driver monitoring.","Title: Data Compression For Simultaneous/Sequential Inference Tasks In Sensor Networks\nYear: 2006\n\nAbstract: Sensor networks typically perform multiple inference tasks and compression is often used to aid in the sharing of data. Compression degrades the inference accuracy and should be optimized for the tasks at hand. Unfortunately, simultaneous optimization for multiple tasks is not generally possible - typically a fundamental trade-off exists that has not been previously explored. A particularly relevant and interesting scenario occurs with a task-driven sequence of inferences. This paper develops a framework for data-optimized data compression for the case of multiple inferences. In particular, the Fisher information matrix (FIM) is used to derive a suitable scalar distortion measure for multiple estimation tasks, while the Chemoff distance is used for decision tasks. Theoretical results are presented that support the use of this particular scalar FIM-based distortion. The method is demonstrated with application to the sequential problem of first detecting a common intercepted signal among sensors and then once detected progressing to the location of the source.","Title: Digital Imaging Sensor Identification (Further Study)\nYear: 2007\n\nAbstract: In this paper, we revisit the problem of digital camera sensor identification using photo-response non-uniformity noise (PRNU). Considering the identification task as a joint estimation and detection problem, we use a simplified model for the sensor output and then derive a Maximum Likelihood estimator of the PRNU. The model is also used to design optimal test statistics for detection of PRNU in a specific image. To estimate unknown shaping factors and determine the distribution of the test statistics for the image-camera match, we construct a predictor of the test statistics on small image blocks. This enables us to obtain conservative estimates of false rejection rates for each image under Neyman-Pearson testing. We also point out a few pitfalls in camera identification using PRNU and ways to overcome them by preprocessing the estimated PRNU before identification.","Title: Imaging sensor noise as digital X-ray for revealing forgeries\nYear: 2007\n\nAbstract: In this paper, we describe a new forensic tool for revealing digitally altered images by detecting the presence of photo-response nonuniformity noise (PRNU) in small regions. This method assumes that either the camera that took the image is available to the analyst or at least some other nontampered images taken by the camera are available. Forgery detection using the PRNU involves two steps - estimation of the PRNU from non-tampered images and its detection in individual image regions. From a simplified model of the sensor output, we design optimal PRNU estimators and detectors. Binary hypothesis testing is used to determine which regions are forged. The method is tested on forged images coming from a variety of digital cameras and with different JPEG quality factors. The approximate probability of falsely identifying a forged region in a non-forged image is estimated by running the algorithm on a large number of non-forged images.","Title: Merging Neuroimaging and Multimedia: Methods, Opportunities, and Challenges\nYear: 2014\n\nAbstract: Neuroimaging and brain mapping can provide meaningful guidance to multimedia analyses. and advanced computational multimedia analysis can be used to better understand the functional mechanisms of the human brain. Essentially, brain imaging and brain mapping techniques can serve as a bridge that links the digital representation of multimedia and the perception and comprehension of its content. This paper summarizes methods that integrate brain imaging with multimedia analysis and discusses the opportunities and challenges in this interdisciplinary field. In general, quantitative modeling of brain responses during multimedia comprehension has advanced content-based multimedia studies such as image and video classification and tagging. Multimedia analysis has promoted functional brain mapping by using naturalistic multimedia as stimuli during neuroimaging. Challenges and opportunities in merging neuroimaging and multimedia include the quantification of the brain's responses, the quantification of multimedia, and the mapping between brain responses and computational multimedia features.","Title: Energy efficiency of MIMO transmissions in wireless sensor networks with diversity and multiplexing gains\nYear: 2005\n\nAbstract: The energy efficiency of MIMO transmissions in wireless sensor networks is analyzed considering the trade-off between diversity and multiplexing gains. Various MIMO are studied with noncooperative, half-cooperative or cooperative realizations. Energies consumed in transmission, processing circuitry and cooperation are obtained, which show that the optimal energy efficiency requires both the diversity and the multiplexing gains be exploited.","Title: Hidden-Markov-Model-Based Segmentation Confidence Applied to Container Code Character Extraction\nYear: 2011\n\nAbstract: Automatic container code recognition (ACCR) has become an indispensable aspect of current intelligent container management systems. In real applications, an ACCR module sometimes faces the problem of missing characters, i.e., not all the 11 container code characters (CCCs) appear in the input image. However, a few of the present methods can process container code images with missing characters. Therefore, a method is proposed to extract the CCCs for both the situation wherein all the 11 CCCs appear in an image and the situation wherein some CCCs are missing. In this method, hidden Markov model (HMM)-based segmentation confidence is proposed to describe the probability of the segmented characters belonging to the container code. Based on the segmentation confidence, the segmented characters are determined whether they belong to the container code or not, and if there are some characters missing, the positions of these characters can be estimated. Various container code images have been used to test the proposed method. The results of the tests show that the method is effective.","Title: Data compression using SVD and Fisher information for radar emitter location\nYear: 2010\n\nAbstract: This paper presents a method that achieves large compression ratios for radar pulse trains exploited in time-difference-of-arrival/frequency-difference-of-arrival (TDOA/FDOA) emitter location; this method exploits pulse-to-pulse redundancy to get a compression ratio much higher than possible by using standard methods. We show how to use (i) the singular value decomposition (SVD) to exploit redundancy between radar pulses, and (ii) a Fisher information-based distortion criterion to enable elimination of pulses that are negligible to the FDOA estimation task. To use the SVD it is necessary to first gate the pulses, place them in a matrix and then align the pulses to get a matrix that is close to rank one. Finally, we employ reasonable coding schemes for the information to be sent and assess the achievable compression level. With such SVD-based coding the compression ratio depends on the number of pulses intercepted and the number of samples taken per pulse; depending on the scenario the compression ratio can range from about 4 up to 100 or more. Fisher information-based removal of pulses is shown to improve the compression ratio beyond what is achievable using only the SVD approach while having negligible impact on the FDOA accuracy; it does, however, degrade the TDOA accuracy. However, we demonstrate that the SVD method includes an inherent de-noising effect (common in SVD-based signal processing) that provides an improvement in TDOA accuracy over the case of no compression processing; thus, the overall impact on TDOA/FDOA accuracy can be negligible while providing significant compression ratios for typical radar signals.","Title: Top-K probabilistic closest pairs query in uncertain spatial databases\nYear: 2011\n\nAbstract: An important topic in the field of spatial data management is processing the queries involving uncertain locations. This paper focuses on the problem of finding probabilistic K closest pairs between two uncertain spatial datasets, namely, Top-K probabilistic closest pairs (TopK-PCP) query, which has popular usages in real applications. Specifically, given two uncertain datasets in which each spatial object is modeled by a set of sample points, a TopK-PCP query retrieves the pairs with top K maximal probabilities of being the closest pair. Due to the inherent uncertainty of data objects, previous techniques to answer K-closest pairs (K-CP) queries cannot be directly applied to our TopK-PCP problem. Motivated by this, we propose a novel method to evaluate TopK-PCP query effectively. Extensive experiments are performed to demonstrate the effectiveness of our method.","Title: An efficient method for cleaning dirty-events over uncertain data in WSNs\nYear: 2011\n\nAbstract: Event detection in wireless sensor networks (WSNs) has attracted much attention due to its importance in many applications. The erroneous abnormal data generated during event detection are prone to lead to false detection results. Therefore, in order to improve the reliability of event detection, we propose a dirty-event cleaning method based on spatio-temporal correlations among sensor data. Unlike traditional fault-tolerant approaches, our method takes into account the inherent uncertainty of sensor measurements and focuses on the type of directional events. A probability-based mapping scheme is introduced, which maps uncertain sensor data into binary data. Moreover, we give formulated definitions of transient dirty-event (TDE) and permanent dirty-event (PDE), which are cleaned by a novel fuzzy method and a collaborative cleaning scheme, respectively. Extensive experimental results show the effectiveness of our dirty-event cleaning method.","Title: Geometry-adaptive data compression for TDOA/FDOA location [wireless sensor network applications]\nYear: 2005\n\nAbstract: The location of an emitting target is estimated by intercepting its emitted signal and sharing it among several sensors to measure the time-difference-of-arrival (TDOA) and the frequency-difference-of-arrival (FDOA). Doing this in a timely and energy efficient fashion, which is especially important for wireless sensor network applications, requires effective data compression. Since the commonly used MSE distortion measure is only weakly related to optimal TDOA/FDOA estimation, in this paper, we derive a new class of non-MSE distortion measures for TDOA/FDOA estimation using the concept of Fisher information. We then use these new distortion measures to compress the data using a wavelet packet transform and show that it improves TDOA/FDOA estimation accuracies relative to using the MSE-based compression. Finally, a scheme of applying our algorithms in a wireless sensor network is proposed, and energy efficiency and accuracy enhancement of the proposed scheme over that of a traditional scheme using MSE is shown through simulations.","Title: Dimensionality reduction with generalized linear models\nYear: 2013\n\nAbstract: In this paper, we propose a general dimensionality reduction method for data generated from a very broad family of distributions and nonlinear functions based on the generalized linear model, called Generalized Linear Principal Component Analysis (GLPCA). Data of different domains often have very different structures. These data can be modeled by different distributions and reconstruction functions. For example, real valued data can be modeled by the Gaussian distribution with a linear reconstruction function, whereas binary valued data may be more appropriately modeled by the Bernoulli distribution with a logit or probit function. Based on general linear models, we propose a unified framework for extracting features from data of different domains. A general optimization algorithm based on natural gradient ascent on distribution manifold is proposed for obtaining the maximum likelihood solutions. We also present some specific algorithms derived from this framework to deal with specific data modeling problems such as document modeling. Experimental results of these algorithms on several data sets are shown for the validation of GLPCA.","Title: Clustering via random walk hitting time on directed graphs\nYear: 2008\n\nAbstract: In this paper, we present a general data clustering algorithm which is based on the asymmetric pairwise measure of Markov random walk hitting time on directed graphs. Unlike traditional graph based clustering methods, we do not explicitly calculate the pairwise similarities between points. Instead, we form a transition matrix of Markov random walk on a directed graph directly from the data. Our algorithm constructs the probabilistic relations of dependence between local sample pairs by studying the local distributions of the data. Such dependence relations are asymmetric, which is a more general measure of pairwise relations than the similarity measures in traditional undirected graph based methods in that it considers both the local density and geometry of the data. The probabilistic relations of the data naturally result in a transition matrix of Markov random walk. Based on the random walk viewpoint, we compute the expected hitting time for all sample pairs, which explores the global information of the structure of the underlying directed graph. An asymmetric measure based clustering algorithm, called K-destinations, is proposed for partitioning the nodes of the directed graph into disjoint sets. By utilizing the local distribution information of the data and the global structure information of the directed graph, our method is able to conquer some limitations of traditional pairwise similarity based methods. Experimental results are provided to validate the effectiveness of the proposed approach.","Title: QUALITY ASSESSMENT OF HYBRID NONLINEAR FILTERS\nYear: 2004\n\nAbstract: Traditionally, researchonadaptivesignal processinghasbeen conducted with the aim of designing adaptive filters with high performance in terms of some prescribed performance measure. However, little is known about how such filters influence the nature of the processed signal. Based upon some recently introduced results on dealing with nonlinear- ity within a signal in hand, we provide a critical assessment of the qualitative performance of common linear and non- linear filters and their combinations. An insight into the performance of so called hybrid filters is provided, which is achieved for combinations of standard nonlinear (neural) and linear filters. It is shown that depending on the appli- cation, it is important not only to look for best filter perfor- mance in terms of some quantitative measure of the error but also for a filter that will not change the character of a signal. Simulation results support the analysis.","Title: Online Detection Of The Modality Of Complex-Valued Real World Signals\nYear: 2008\n\nAbstract: A novel method for the online detection of the modality of complex-valued nonlinear and nonstationary signals is introduced. This is achieved using a convex combination of complex nonlinear adaptive filters with different transient characteristics. To facilitate the online mode of operation, the convex mixing parameter. within the proposed architecture is made gradient adaptive. Our focus is on the most important aspect of complex nonlinear modeling, that is, the identification of the split-complex and fully-complex nature of the signal in hand. The algorithms derived are robust and capable of tracking the changes in the modality of both benchmark and real world radar and wind complex vector fields.","Title: Study On Arc Characteristics Of A Dc Bridge-Type Contact In Air And Nitrogen At Different Pressure\nYear: 2014\n\nAbstract: High voltage DC contactors, for operation at voltage levels up to at least about 300 volts, find their increasing markets in applications such as electrical vehicles and aircrafts in which size and weight of cables are of extreme importance. The copper bridge-type contact, cooperated with magnetic field provided by permanent magnets and sealed in an arc chamber filled with high pressure gases, is a mainly used structure to interrupt the DC arc rapidly. Arc characteristic in different gases at different pressure varies greatly. This paper is focused on the arc characteristics of the bridge-type contact system when magnetic field is applied with nitrogen and gas at different pressure. The pressure of the gases varies from 1 atm to 2.5 atm. Arc characteristics, such as arc durations at different stages and arc motions in those gases are comparatively studied. The results are instructive for choosing the suitable arcing atmosphere in a DC bridge-type arc chamber of a contactor.","Title: A New Framework For Container Code Recognition By Using Segmentation-Based And Hmm-Based Approaches\nYear: 2015\n\nAbstract: Traditional methods for automatic recognition of container code in visual images are based on segmentation and recognition of isolated characters. However, when the segment fails to separate each character from the others, those methods will not function properly. Sometimes the container code characters are printed or arranged very closely, which makes it a challenge to isolate each character. To address this issue, a new framework for automatic container code recognition (ACCR) in visual images is proposed in this paper. In this framework, code-character regions are first located by applying a horizontal high-pass filter and scan line analysis. Then, character blocks are extracted from the code-character regions and further classified into two categories, i.e. single-character block and multi-character block. Finally, a segmentation-based approach is implemented for recognition of the characters in single-character blocks, and a hidden Markov model (HMM)-based method is proposed for the multi-character blocks. The experimental results demonstrate the effectiveness of the proposed method, which can successfully recognize the container code with closely arranged characters.","Title: Safe Sequential Path Planning Of Multi-Vehicle Systems Via Double-Obstacle Hamilton-Jacobi-Isaacs Variational Inequality\nYear: 2014\n\nAbstract: We consider the problem of planning trajectories for a group of N vehicles, each aiming to reach its own target set while avoiding danger zones of other vehicles. The analysis of problems like this is extremely important practically, especially given the growing interest in utilizing unmanned aircraft systems for civil purposes. The direct solution of this problem by solving a single-obstacle Hamilton-Jacobi-Isaacs (HJI) variational inequality (VI) is numerically intractable due to the exponential scaling of computation complexity with problem dimensionality. Furthermore, the single-obstacle HJI VI cannot directly handle situations in which vehicles do not have a common scheduled arrival time. Instead, we perform sequential path planning by considering vehicles in order of priority, modeling higher-priority vehicles as time-varying obstacles for lower-priority vehicles. To do this, we solve a double-obstacle HJI VI which allows us to obtain the reach-avoid set, defined as the set of states from which a vehicle can reach its target while staying within a time-varying state constraint set. From the solution of the double-obstacle HJI VI, we can also extract the latest start time and the optimal control for each vehicle. This is a first application of the double-obstacle HJI VI which can handle systems with time-varying dynamics, target sets, and state constraint sets, and results in computation complexity that scales linearly, as opposed to exponentially, with the number of vehicles in consideration.","Title: A Memristive Diode Bridge-Based Canonical Chua's Circuit.\nYear: 2014\n\nAbstract: A novel memristor circuit is presented, which is generated from the canonical Chua's circuit by replacing the Chua's diode with a first order memristive diode bridge. The circuit dynamical characteristics with the variations of circuit parameters are investigated both theoretically and numerically. It can be found that the circuit has three determined equilibrium points, including a zero saddle point and two nonzero saddle-foci with index 2. Specially, the circuit is non-dissipative in the neighborhood of the zero saddle point, and there exists complex nonlinear phenomena of coexisting bifurcation modes and coexisting chaotic attractors. Experimental observations are performed to verify the numerical simulation results.","Title: Study of the product color's image based on the event-related potentials.\nYear: 2014\n\nAbstract: This research presents a new approach to explore the relationship between perception of product's color and their image. Event-related potentials (ERP) are used to reveal the brain responds to variation of image words within the same color category. Sofa was used as an example in this study. Firstly, all of the sample sofa pictures were made in the warm color tone according to the HSB color space; Next, through a questionnaire survey, we deduced that the three adjective words to match the color in three degree are: (i) passionate, (ii) mild, (iii) refreshing. The evaluation result showed that the reaction time were shorter for Related (passionate) and Conflict words (mild) than for the Vague word (refreshing). P200 and N400 components were identified in the -100 to 600 ms interval by the repeated analysis. The P200 component was larger for the related condition than for the unrelated condition, in addition, a right anterior P200 effect was observed. Meanwhile, the N400 component can be elicited by both Vague word and Conflict word, which suggested that these two kinds of word were not match the image of the target color. These findings reveal that the ERP can identify the relationship between semantic and perception of color sensitively, therefore, can help designers in achieving a desirable image of product's color effectively.","Title: Multiplayer reach-avoid games via low dimensional solutions and maximum matching\nYear: 2014\n\nAbstract: We consider a multiplayer reach-avoid game with an equal number of attackers and defenders moving with simple dynamics on a two-dimensional domain possibly with obstacles. The attacking team attempts to send as many attackers to a certain target location as possible quickly while the defenders aim to capture the attackers to prevent the attacking team from reaching its goal. The analysis of problems like this plays an important role in collision avoidance, motion planning, and aircraft control, among other applications. Computing optimal solutions for such multiplayer games is intractable due to numerical intractibility. This paper provides a first attempt to address such computational intractability by combining maximum matching in graph theory with the classical Hamilton-Jacobi-Isaacs approach. In addition, our solution provides an initial step to take cooperation into account by computing maximum matching in real time.","Title: Design of a neural decoder by sensory prediction and error correction\nYear: 2014\n\nAbstract: Brain-machine interfaces (BMI) hold great potential to improve the quality of life of many patients with disabilities. The neural decoder, which expresses the mapping between the neural signals and the subject's motion, plays an important role in BMI systems. Conventional neural decoders are generally in the form of a kinematic Kalman filter which does not possess an explicit mechanism to deal with the unavoidable mismatch between the biological system and the model of the system used by the decoder. This paper presents a novel design of a neural decoder that uses a one-step model predictive controller to generate a control signal that compensates for the inherent model mismatch. The effectiveness of the proposed decoding algorithm compares favorably to the state-of-the-art Kalman filter in numerical simulations with different degrees of model mismatch.","Title: A path defense approach to the multiplayer reach-avoid game\nYear: 2014\n\nAbstract: We consider a multiplayer reach-avoid game played between N attackers and N defenders moving with simple dynamics on a general two-dimensional domain. The attackers attempt to win the game by sending at least M of them (1 ≤ M ≤ N) to a target location while the defenders try to prevent the attackers from doing so by capturing them. The analysis of this game plays an important role in collision avoidance, motion planning, and aircraft control, among other applications involving cooperative agents. The high dimensionality of the game makes computing an optimal solution for either side intractable when N > 1. The solution is difficult even when N = 1. To address this issue, we present an efficient, approximate solution to the 1 vs. 1 problem. We call the approximate solution the “path defense solution”, which is conservative towards the defenders. This serves as a building block for an approximate solution of the multiplayer game. Compared to the classical Hamilton-Jacobi-Isaacs approach for solving the 1 vs. 1 game, our new method is orders of magnitude faster, and scales much better with the number of players.","Title: The Study Of Data Governance For Telecom Network Management\nYear: 2014\n\nAbstract: Data is an important asset of telecom operators, and data governance is an important method for telecom operators to manage data. This paper studies the characteristics of BSS and OSS data telecom operators, and proposes the architecture of data fusion platform and data hierarchical model. The basic method of BSS and OSS data fusion is then presented, and the wide table technology is adopted to organize and unify data model layer in order to realize the construction of the confusion application supporting cross-domain data fusion.","Title: Qoe-Oriented Resource Allocation For Femtocell Networks\nYear: 2014\n\nAbstract: This paper studies the resource allocation in a femtocell network, which aims to maximize the user-perceived Quality of Experience (QoE). By introducing a QoE-based assessment model, the problem is formulated as a combinational optimization problem, which is non-concave and difficult to develop a final solution. A heuristic PRB (Physical Resource Block) allocation algorithm and an adaptive power allocation algorithm are proposed for the final solution, in which a priority mechanism is employed for the network to give a higher priority on its resources to subscribers than the public users. Simulation results show that the proposed algorithms can improve the overall perceived quality from the user's perspective in compassion with the traditional Quality of Service (QoS) oriented algorithm.","Title: Defending Against Fingerprint-Copy Attack in Sensor-Based Camera Identification\nYear: 2011\n\nAbstract: Sensor photoresponse nonuniformity has been proposed as a unique identifier (fingerprint) for various forensic tasks, including digital-camera ballistics in which an image is matched to the specific camera that took it. The problem investigated here concerns the situation when an adversary estimates the sensor fingerprint from a set of images and superimposes it onto an image from a different camera to frame an innocent victim. This paper proposes a reliable method for detecting such fake fingerprints under rather mild and general assumptions about the adversary's activity and the means available to the victim. The proposed method is subjected to experiments to evaluate its reliability as well as its limitations. The conclusion that can be made from this study is that planting a sensor fingerprint in an image without leaving a trace is significantly more difficult than previously thought.","Title: A Built-in Single Event Upsets Detector for Sequential Cells\nYear: 2016\n\nAbstract: Abstract A built-in single event upsets (SEUs) detector is presented in this paper. This detector utilizes charge sharing to detect an SEU in a sequential cell, and the detection process is analyzed through Accuro simulations in a 65 nm technology. The normal operation of this detector would not induce obvious performance degradation of the target circuit. Through using this detector, error correction can be achieved based on dual modular redundancy (DMR) while the related power is about 20.4 % lower than that induced by triple modular redundancy (TMR).","Title: Self-Excited And Hidden Attractors Found Simultaneously In A Modified Chua'S Circuit\nYear: 2015\n\nAbstract: By replacing the Chua's diode in Chua's circuit with a first-order hybrid diode circuit, a fourth-order modified Chua's circuit is presented. The circuit has an unstable zero saddle point and two nonzero saddle-foci. By Routh-Hurwitz criterion, it is found that in a narrow parameter region, the two nonzero saddle-foci have a transition from unstable to stable saddle-foci, leading to generations of self-excited and hidden attractors in the modified Chua's circuit simultaneously, which have not been previously reported. Complex dynamical behaviors are investigated both numerically and experimentally. The results indicate that the proposed circuit exhibits complicated nonlinear phenomena including self-excited attractors, coexisting self-excited attractors, hidden attractors, and coexisting hidden attractors.","Title: Comparisons On Arc Behavior And Contact Performance Between Cu And Cu-Mo Alloys In A Bridge-Type Contact System\nYear: 2015\n\nAbstract: Cu-Mo alloy carries forward not only high electrical conductivity and high thermal conductivity from Cu but also high hardness from Mo, which makes it a promising potential application in electrical contact fields. In this paper, arc characteristic and erosion characteristic of Cu-Mo contacts are studied with a bridge-type contact high speed break mechanism on DC270 V/200 A load condition. And in each experiment group, 2500 times break operations are carried out. During every break operation, a high-speed AD card is used to record voltage and current signal of the arc, a high-speed camera is applied to record arcing process, and the temperature of contacts and arc are acquired by thermocouple and spectrometer, respectively. The mass and contact resistance of contacts are measured before and after every group experiment. Besides, the photograph of contact surface is taken by SEM to help analyze the erosion characteristic. The comparison between Cu-Mo contacts and Cu contacts indicates that although Cu contacts have a better electrical conductivity and thermal conductivity, Cu-Mo contacts can decrease the temperature of arc to prevent thermal breakdown, and they are also harder to be ablated and have a longer life span.","Title: Guaranteeing Safety and Liveness of Unmanned Aerial Vehicle Platoons on Air Highways.\nYear: 2016\n\nAbstract: Recently, there has been immense interest in using unmanned aerial vehicles (UAVs) for civilian operations such as package delivery, aerial surveillance, and disaster response. As a result, UAV traffic management systems are needed to support potentially thousands of UAVs flying simultaneously in the air space, in order to ensure their liveness and safety requirements are met. Currently, the analysis of large multi-agent systems cannot tractably provide these guarantees if the agentsu0027 set of maneuvers are unrestricted. In this paper, we propose to have platoons of UAVs flying on air highways in order to impose the air space structure that allows for tractable analysis and intuitive monitoring. For the air highway placement problem, we use the flexible and efficient fast marching method to solve the Eikonal equation, which produces a sequence of air highways that minimizes the cost of flying from an origin to any destination. Within the platoons that travel on the air highways, we model each vehicle as a hybrid system with modes corresponding to its role in the platoon. Using Hamilton-Jacobi reachability, we propose several liveness controllers and a safety controller that guarantee the success and safety of all mode transitions. For a single altitude range, our approach guarantees safety for one safety breach per vehicle; in the unlikely event of multiple safety breaches, safety can be guaranteed over multiple altitude ranges. We demonstrate the satisfaction of liveness and safety requirements through simulations of three common scenarios.","Title: Multi-Vehicle Collision Avoidance Via Hamilton-Jacobi Reachability And Mixed Integer Programming\nYear: 2016\n\nAbstract: Multi-agent differential games are important and useful tools for analyzing many practical problems. With the recent surge of interest in using UAVs for civil purposes, the importance and urgency of developing tractable multi-agent analysis techniques that provide safety and performance guarantees is at an all-time high. Hamilton-Jacobi (HJ) reachability has successfully provided safety guarantees to small-scale systems and is flexible in terms of system dynamics. However, the exponential complexity scaling of HJ reachability prevents its direct application to large scale problems when the number of vehicles is greater than two. In this paper, we overcome the scalability limitations of HJ reachability by using a mixed integer program that exploits the properties of HJ solutions to provide higher-level control logic. Our proposed method provides safety guarantee for three-vehicle systems - a previously intractable task for HJ reachability - without incurring significant additional computation cost. Furthermore, our method is scalable beyond three vehicles and performs significantly better by several metrics than an extension of pairwise collision avoidance to multi-vehicle collision avoidance. We demonstrate our proposed method in simulations.","Title: Safe Sequential Path Planning of Multi-Vehicle Systems Under Presence of Disturbances and Imperfect Information.\nYear: 2016\n\nAbstract: Recently, there has been an immense surge of interest in using unmanned aerial vehicles (UAVs) for civil purposes. Multi-UAV systems are safety-critical, and safety guarantees must be made to ensure no undesirable configurations such as collisions occur. Hamilton-Jacobi (HJ) reachability is ideal for analyzing such safety-critical systems because it provides safety guarantees and is flexible in terms of system dynamics; however, its direct application is limited to small-scale systems of no more than two vehicles because of the exponential-scaling computation complexity. By assigning vehicle priorities, the sequential path planning (SPP) method allows multi-vehicle path planning to be done with a computation complexity that scales linearly with the number of vehicles. Previously the SPP method assumed no disturbances in the vehicle dynamics, and that every vehicle has perfect knowledge of the position of higher-priority vehicles. In this paper, we make SPP more practical by providing three different methods for accounting for disturbances in dynamics and imperfect knowledge of higher-priority vehicles. Each method has advantages and disadvantages with different assumptions about information sharing. We demonstrate our proposed methods in simulations.","Title: Accelerating submovement decomposition with search space reduction heuristics\nYear: 2015\n\nAbstract: Movements made by healthy individuals can be characterized as superpositions of smooth bell-shaped velocity curves. Decomposing complex movements into these simpler “submovement” building blocks is useful for studying the neural control of movement as well as measuring motor impairment due to neurological injury. Approach: One prevalent strategy to submovement decomposition is to formulate it as an optimization problem. This optimization problem is non-convex and finding an exact solution is computationally burdensome. We build on previous literature which generated approximate solutions to the submovement optimization problem. Results: First, we demonstrate broad conditions on the submovement building block functions that enable the optimization variables to be partitioned into disjoint subsets, allowing for a faster alternating minimization solution. Specifically, the amplitude parameters of a submovement can typically be fit independently of its shape parameters. Second, we develop a method to concentrate the search in regions of high error to make more efficient use of optimization routine iterations. Conclusion: Both innovations result in substantial reductions in computation time across multiple non-human primate subjects and diverse task conditions. Significance: These innovations may accelerate analysis of submovements for basic neuroscience and enable realtime applications of submovement decomposition.","Title: Application of STBC-encoded cooperative transmissions in wireless sensor networks\nYear: 2005\n\nAbstract: The efficiency of space-time block code-encoded (STBC) cooperative transmission is studied within low-energy adaptive clustering hierarchy (LEACH), which is a typical networking/communication protocol for wireless sensor networks. Cooperation protocol with low overhead is proposed, and synchronization requirements among cooperating sensors are discussed. Energy efficiency is analyzed as a tradeoff...","Title: Identifying valence and arousal levels via connectivity between EEG channels\nYear: 2015\n\nAbstract: Implicit emotion tagging is a central theme in the area of affective computing. To this end, Several physiological signals acquired from subjects can be employed, for example, electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) from brain, electrocardiography (ECG) from cardiac activities, and other peripheral physiological signals, such as galvanic skin resistance, electromyogram (EMG), blood volume pressure etc. Brain is regarded as the place where emotional activities evoke. Determining affective states by observing brain activities directly is of therefore great interest. There are several published works that use EEG signals to identify affective states in different aspects with various stimuli, e.s., images, musics and videos. In this paper, we propose to adopt EEG connectivity between electrodes to identify subjects' affective levels in both valence and arousal space during video stimuli presentation. Three catagories of connectivity are adopted in magnitude and phase domains. One open accessed affective database, DEAP, is used as benchmark. We will show that with the proposed connectivity-based representation, the accuracy of affective levels identification tasks are higher than the same tasks in existing works based on same database.","Title: Reach-avoid problems with time-varying dynamics, targets and constraints\nYear: 2015\n\nAbstract: We consider a reach-avoid differential game, in which one of the players aims to steer the system into a target set without violating a set of state constraints, while the other player tries to prevent the first from succeeding; the system dynamics, target set, and state constraints may all be time-varying. The analysis of this problem plays an important role in collision avoidance, motion planning and aircraft control, among other applications. Previous methods for computing the guaranteed winning initial conditions and strategies for each player have either required augmenting the state vector to include time, or have been limited to problems with either no state constraints or entirely static targets, constraints and dynamics. To incorporate time-varying dynamics, targets and constraints without the need for state augmentation, we propose a modified Hamilton-Jacobi-Isaacs equation in the form of a double-obstacle variational inequality, and prove that the zero sublevel set of its viscosity solution characterizes the capture basin for the target under the state constraints. Through this formulation, our method can compute the capture basin and winning strategies for time-varying games at virtually no additional computational cost relative to the time-invariant case. We provide an implementation of this method based on well-known numerical schemes and show its convergence through a simple example; we include a second example in which our method substantially outperforms the state augmentation approach.","Title: An SEU-Resilient SRAM Bitcell in 65-nm CMOS Technology.\nYear: 2016\n\nAbstract: This paper presents an SEU-resilient 12 T SRAM bitcell. Simulation results demonstrate that it has higher critical charge than the traditional 6 T cell. Alpha and proton testing results validate that it has a lower soft error rate compared to the reference designs for all data patterns and supply voltage levels. The improvement in SEU tolerance is achieved at the expense of 2X area penalty.","Title: Novel Hotspot Information Analysis System Using Automatic Information Extraction.\nYear: 2016\n\nAbstract: There is large amount of information available on the Internet, which introduces difficulties in capturing and analyzing hotspot information. In this paper, we propose a novel hotspot information analysis system with automatic information extraction using the technologies of internet crawling, similarity elimination and abstract generation. System verification results show that, compared to the traditional solutions based on manual extraction and analysis, the proposed method are more capable of realizing the automated information extraction and analysis, thus improve the efficiency of hotspot analysis.","Title: Instruction-Vulnerability-Factor-Based Reliability Analysis Model for Program Memory.\nYear: 2016\n\nAbstract: Bit faults induced by single-event upsets in instruction may not cause a system to experience an error. The instruction vulnerability factor (IVF) is first defined to quantify the effect of non-effective upsets on program reliability in this paper; and the mean time to failure (MTTF) model of program memory is then derived based on IVF. Further analysis of MTTF model concludes that the MTTF of program memory using error correcting code (ECC) and scrubbing is not always better than unhardened program memory. The constraints that should be met upon utilizing ECC and scrubbing in program memory are presented for the first time, to the best of authors' knowledge. Additionally, the proposed models and conclusions are validated by Monte Carlo simulations in MATLAB. These results show that the proposed models have a good accuracy and their margin of error is less than 3 % compared with MATLAB simulation results. It should be highlighted that our conclusions may be used to contribute to selecting the optimal fault-tolerant technique to harden the program memory.","Title: Using Neural Networks for Fast Reachable Set Computations.\nYear: 2016\n\nAbstract: Hamilton-Jacobi (HJ) reachability is a powerful tool that provides performance and safety guarantees for dynamical systems. Unfortunately, using the state-of-the-art dynamic programming-based approaches, HJ reachability is intractable for systems with more than five dimensions because its computational complexity scales exponentially with system dimension. To sidestep the curse of dimensionality, we propose an algorithm that leverages a neural network to approximate the minimum time-to-reach function to synthesize controls. We show that our neural network generates near optimal controls which are guaranteed to successfully drive the system to a target state. Our framework is not dependent on state space discretization, leading to a significant reduction in computation time and space complexity in comparison with dynamic programming-based approaches. Using this grid-free approach also enables us to plan over longer time horizons with relatively little additional computation overhead. Unlike many previous neural network reachability formulations, our approximation is conservative and hence any trajectories we generate will be strictly feasible. For demonstration, we specialize our new general framework to the Dubins car model and discuss how the general framework can be applied to other models with higher-dimensional state spaces.","Title: Robust Sequential Path Planning Under Disturbances and Adversarial Intruder.\nYear: 2016\n\nAbstract: Provably safe and scalable multivehicle trajectory planning is an important and urgent problem. Although this problem has been studied in the past, there has not been a method that guarantees both goal satisfaction and safety for vehicles with general nonlinear dynamics, while taking into account disturbances and potential adversarial agents, to the best of our knowledge. Hamilton-Jacobi (HJ) reachability is the ideal tool for guaranteeing goal satisfaction and safety under such scenarios, which has been successfully applied to many small-scale problems; however, its direct application in most cases becomes intractable when there are more than two vehicles due to the exponentially scaling computational complexity with respect to system dimension. In this paper, we take advantage of the guarantees provided by HJ reachability and eliminate the computation burden by assigning a strict priority ordering to vehicles under consideration. Under this sequential trajectory planning (STP) scheme, vehicles reserve portions in the airspace. The space-time portions guarantee dynamic feasibility, collision avoidance, and optimality of trajectories given the priority ordering. With a computation complexity that scales quadratically when accounting for both disturbances and an intruder, and linearly when accounting for only disturbances, the STP can tractably solve the multivehicle trajectory planning problem for vehicles with general nonlinear dynamics in a practical setting. We demonstrate our theory in representative simulations.","Title: Fast Reachable Set Approximations Via State Decoupling Disturbances\nYear: 2016\n\nAbstract: With the recent surge of interest in using robotics and automation for civil purposes, providing safety and performance guarantees has become extremely important. In the past, differential games have been successfully used for the analysis of safety-critical systems. In particular, the Hamilton-Jacobi (HJ) formulation of differential games provides a flexible way to compute the reachable set, which can characterize the set of states which lead to either desirable or undesirable configurations, depending on the application. While HJ reachability is applicable to many small practical systems, the curse of dimensionality prevents the direct application of HJ reachability to many larger systems. To address computation complexity issues, various efficient computation methods in the literature have been developed for approximating or exactly computing the solution to HJ partial differential equations, but only when the system dynamics are of specific forms. In this paper, we propose a flexible method to trade off optimality with computation complexity in HJ reachability analysis. To achieve this, we propose to simplify system dynamics by treating state variables as disturbances. We prove that the resulting approximation is conservative in the desired direction, and demonstrate our method using a four-dimensional plane model.","Title: An implicit feedback integrated LDA-based topic model for IPTV program recommendation\nYear: 2016\n\nAbstract: Internet protocol television (IPTV), the television services through the Internet, has become more and more popular in recent years. Many recommendation systems have been made for delivering personalized IPTV services, of which understanding users' preference is the most critical. The traditional recommendation system only considers the users' playing behavior, but other implicit feedback behaviors of users, such as browsing, collecting also reflect the users' preference. We propose a novel latent Dirichlet allocation (LDA)-based model, which considers users' playing behavior as well as the implicit feedback of browsing and collecting, to capture the inherent viewing preference of individual users. The implicit feedback integrated LDA model employs three LDA models (the playing, browsing, and collecting behavior topic model), which are integrated via TV program characteristic. Based on this, we further calculate the ratio of each behavior to the recommended results by logistic regression algorithm. The experimental results show that the proposed topic model yields an average 32.5% precision for recommending 10 videos and 200 topics in IPTV recommendation, and its performance is an average of 19.5% higher than that of LDA using playing behavior only.","Title: Multiplayer Reach-Avoid Games via Pairwise Outcomes.\nYear: 2017\n\nAbstract: A multiplayer reach-avoid game is a differential game between an attacking team with N A attackers and a defending team with N D defenders playing on a compact domain with obstacles. The attacking team aims to send M of the N A attackers to some target location, while the defending team aims to prevent that by capturing attackers or indefinitely delaying attackers from reaching the target. Although the analysis of this game plays an important role in many applications, the optimal solution to this game is computationally intractable when N A > 1 or N D > 1. In this technical note, we present two approaches for the N A = N D = 1 case to determine pairwise outcomes, and a graph theoretic maximum matching approach to merge these pairwise outcomes for an N A , N D > 1 solution that provides guarantees on the performance of the defending team. We will show that the four-dimensional Hamilton-Jacobi-Isaacs approach allows for real-time updates to the maximum matching, and that the two-dimensional path defense approach is considerably more scalable with the number of players while maintaining defender performance guarantees.","Title: Provably Safe and Robust Drone Routing via Sequential Path Planning: A Case Study in San Francisco and the Bay Area.\nYear: 2017\n\nAbstract: Provably safe and scalable multi-vehicle path planning is an important and urgent problem due to the expected increase of automation in civilian airspace in the near future. Hamilton-Jacobi (HJ) reachability is an ideal tool for analyzing such safety-critical systems and has been successfully applied to several small-scale problems. However, a direct application of HJ reachability to large scale systems is often intractable because of its exponentially-scaling computation complexity with respect to system dimension, also known as the \"curse of dimensionality\". To overcome this problem, the sequential path planning (SPP) method, which assigns strict priorities to vehicles, was previously proposed; SPP allows multi-vehicle path planning to be done with a linearly-scaling computation complexity. In this work, we demonstrate the potential of SPP algorithm for large-scale systems. In particular, we simulate large-scale multi-vehicle systems in two different urban environments, a city environment and a multi-city environment, and use the SPP algorithm for trajectory planning. SPP is able to efficiently design collision-free trajectories in both environments despite the presence of disturbances in vehicles' dynamics. To ensure a safe transition of vehicles to their destinations, our method automatically allocates space-time reservations to vehicles while accounting for the magnitude of disturbances such as wind in a provably safe way. Our simulation results show an intuitive multi-lane structure in airspace, where the number of lanes and the distance between the lanes depend on the size of disturbances and other problem parameters.","Title: Exact and efficient Hamilton-Jacobi guaranteed safety analysis via system decomposition\nYear: 2017\n\nAbstract: Hamilton-Jacobi (HJ) reachability is a method that provides rigorous analyses of the safety properties of dynamical systems. These guarantees can be provided by the computation of a backward reachable set (BRS), which represents the set of states from which the system may be driven into violating safety properties despite the system's best effort to remain safe. Unfortunately, the complexity of the BRS computation scales exponentially with the number of state dimensions. Although numerous approximation techniques are able to tractably provide conservative estimates of the BRS, they often require restrictive assumptions about system dynamics without providing an exact solution. In this paper we propose a general method for decomposing dynamical systems. Even when the resulting subsystems are coupled, relatively high-dimensional BRSs that were previously intractable or expensive to compute can now be quickly and exactly computed in lower-dimensional subspaces. As a result, the curse of dimensionality is alleviated to a large degree without sacrificing optimality. We demonstrate our theoretical results through a 3D Dubins Car model and a 6D Acrobatic Quadrotor model.","Title: Safe Sequential Path Planning Under Disturbances And Imperfect Information\nYear: 2017\n\nAbstract: Multi-UAV systems are safety-critical, and guarantees must be made to ensure no unsafe configurations occur. Hamilton-Jacobi (HJ) reachability is ideal for analyzing such safety-critical systems; however, its direct application is limited to small-scale systems of no more than two vehicles due to an exponentially-scaling computational complexity. Previously, the sequential path planning (SPP) method, which assigns strict priorities to vehicles, was proposed; SPP allows multi-vehicle path planning to be done with a linearly-scaling computational complexity. However, the previous formulation assumed that there are no disturbances, and that every vehicle has perfect knowledge of higher-priority vehicles' positions. In this paper, we make SPP more practical by providing three different methods to account for disturbances in dynamics and imperfect knowledge of higher-priority vehicles' states. Each method has different assumptions about information sharing. We demonstrate our proposed methods in simulations.","Title: A Study for Human-Machine Interface Design of Spacecraft Display & Control Device Based on Eye-Tracking Experiments.\nYear: 2017\n\nAbstract: The display & control device is the hub of human-machine interaction in the whole spacecraft's human-machine environment system. The rationality of its design affects the level of integration between human and machine directly. Therefore, the optimization design studies of manned spacecraft cabin's display & control device plays an important role on the development of spaceflight. The paper researches the design methods of manned spacecraft cabin's display & control device from the perspective of human-machine ergonomics. The specific steps of research are: Firstly, we will refine the design principles of human-machine interface by constructing the user behavior model; Secondly, we will work out the design and layout solutions of spacecraft cabin's display & control device based on the information from user behavior model; Finally, an eye-tracking experiment will be proposed to verify and optimize the solutions.","Title: JPEG-Phase-Aware Convolutional Neural Network for Steganalysis of JPEG Images\nYear: 2017\n\nAbstract: Detection of modern JPEG steganographic algorithms has traditionally relied on features aware of the JPEG phase. In this paper, we port JPEG-phase awareness into the architecture of a convolutional neural network to boost the detection accuracy of such detectors. Another innovative concept introduced into the detector is the \\\"catalyst kernel\\\" that, together with traditional high-pass filters used to pre-process images allows the network to learn kernels more relevant for detection of stego signal introduced by JPEG steganography. Experiments with J-UNIWARD and UED-JC embedding algorithms are used to demonstrate the merit of the proposed design.","Title: BPPT — Bulk potential protection technique for hardened sequentials\nYear: 2017\n\nAbstract: In this paper, we present a method for hardening memory and sequential cells against soft errors. The effect of the ionizing particle on the bulk potential is exploited to prevent the induced SET from propagating in the circuit. The proposed method requires a minimum number of extra transistors. The solution is applied to D Flip-Flop design, and alpha and heavy-ions test results are presented.","Title: Coexisting Behaviors of Asymmetric Attractors in Hyperbolic-Type Memristor based Hopfield Neural Network.\nYear: 2017\n\nAbstract: A new hyperbolic-type memristor emulator is presented and its frequency-dependent pinched hysteresis loops are analyzed by numerical simulations and confirmed by hardware experiments. Based on the emulator, a novel hyperbolic-type memristor based 3-neuron Hopfield neural network (HNN) is proposed, which is achieved through substituting one coupling-connection weight with a memristive synaptic weight. It is numerically shown that the memristive HNN has a dynamical transition from chaotic, to periodic, and further to stable point behaviors with the variations of the memristor inner parameter, implying the stabilization effect of the hyperbolic-type memristor on the chaotic HNN. Of particular interest, it should be highly stressed that for different memristor inner parameters, different coexisting behaviors of asymmetric attractors are emerged under different initial conditions, leading to the existence of multistable oscillation states in the memristive HNN. Furthermore, by using commercial discrete components, a nonlinear circuit is designed and PSPICE circuit simulations and hardware experiments are performed. The results simulated and captured from the realization circuit are consistent with numerical simulations, which well verify the facticity of coexisting asymmetric attractors' behaviors.","Title: Hamilton-Jacobi Reachability: A Brief Overview And Recent Advances\nYear: 2017\n\nAbstract: Hamilton-Jacobi (HJ) reachability analysis is an important formal verification method for guaranteeing performance and safety properties of dynamical systems; it has been applied to many small-scale systems in the past decade. Its advantages include compatibility with general nonlinear system dynamics, formal treatment of bounded disturbances, and the availability of well-developed numerical tools. The main challenge is addressing its exponential computational complexity with respect to the number of state variables. In this tutorial, we present an overview of basic HJ reachability theory and provide instructions for using the most recent numerical tools, including an efficient GPU-parallelized implementation of a Level Set Toolbox for computing reachable sets. In addition, we review some of the current work in high-dimensional HJ reachability to show how the dimensionality challenge can be alleviated via various general theoretical and application-specific insights.","Title: Safe and Resilient Multi-vehicle Trajectory Planning Under Adversarial Intruder.\nYear: 2017\n\nAbstract: Provably safe and scalable multi-vehicle trajectory planning is an important and urgent problem. Hamilton-Jacobi (HJ) reachability is an ideal tool for analyzing such safety-critical systems and has been successfully applied to several small-scale problems. However, a direct application of HJ reachability to multi-vehicle trajectory planning is often intractable due to the curse of dimensionality. To overcome this problem, the sequential trajectory planning (STP) method, which assigns strict priorities to vehicles, was proposed, STP allows multi-vehicle trajectory planning to be done with a linearly-scaling computation complexity. However, if a vehicle not in the set of STP vehicles enters the system, or even worse, if this vehicle is an adversarial intruder, the previous formulation requires the entire system to perform replanning, an intractable task for large-scale systems. In this paper, we make STP more practical by providing a new algorithm where replanning is only needed only for a fixed number of vehicles, irrespective of the total number of STP vehicles. Moreover, this number is a design parameter, which can be chosen based on the computational resources available during run time. We demonstrate this algorithm in a representative simulation of an urban airspace environment.","Title: A Hybrid Framework For Multi-Vehicle Collision Avoidance\nYear: 2017\n\nAbstract: With the recent surge of interest in UAVs for civilian services, the importance of developing tractable multi-agent analysis techniques that provide safety and performance guarantees has drastically increased. Hamilton-Jacobi (HJ) reachability has successfully provided these guarantees to small-scale systems and is flexible in terms of system dynamics. However, the exponential complexity scaling of HJ reachability with respect to system dimension prevents its direct application to larger-scale problems where the number of vehicles is greater than two. In this paper, we propose a collision avoidance algorithm using a hybrid framework for N + 1 vehicles through higher-level control logic given any N-vehicle collision avoidance algorithm. Our algorithm conservatively approximates a guaranteed-safe region in the joint state space of the N + 1 vehicles and produces a safety-preserving controller. In addition, our algorithm does not incur significant additional computation cost. We demonstrate our method in simulation.","Title: A Method Of Large - Scale Log Pattern Mining\nYear: 2017\n\nAbstract: With the development of the telecommunication network, more and more devices are used in the network, which has been a burden for the network operation and maintenance. At the same time, network devices generate large amounts of log data every day, recording the activities of each device in detail. As a result, the log can reflect the performance of network state, and sometimes, we can predict the occurrence of network failure based on the log. However, since the log has such features: big volume, multi-source heterogeneous and difficult to understand, people have not reasonably used it to analyze and predict network failure. Therefore, we propose a method for structuring a large number of device logs in the short term, and use the data generated from a real communication device network to verify the effect. Besides, we compare our method with the traditional log parsers, such as regular expressions, LogSig, etc. to demonstrate the efficient processing performance and accurate pattern extraction analysis for massive network device logs.","Title: Identifying affective levels on music video via completing the missing modality.\nYear: 2018\n\nAbstract: Emotion tagging is one theme of interest in affective computing, which labels stimuli with human understandable semantic information. Previous works indicate that modality fusion could improve the performance of this kind of tasks. However, acquiring the subjects’ responses is costly and time consuming, leading to that the response modality is absent for large part of multimedia contents, which is required by modality fusion methods. To address this problem, in this paper a novel emotion tagging framework is proposed, which completes the missing response modalities based on the conception of brain encoding. In the framework, an encoding model is built based on the response modality from subjects’ responses and the stimulus modality from stimulus contents. Then the model is applied to those videos whose response modalities are absent to complete the missing response modalities. Modality fusion is finally conducted on stimulus modality and response modality and followed by the classification methods. To test the performance of the proposed framework, DEAP dataset is adopted as a benchmark. In the experiments, three kinds of features are employed as stimulus modalities. Response modality and fused modality are computed under the proposed framework. Affective level identification is conducted as emotion tagging task. The results demonstrate that the accuracies of the proposed framework outperforms the accuracies obtained by using only stimulus modality. The improvements are higher than 5% for all kinds of stimulus modalities in valence and arousal in terms of accuracy. Additionally, the improvement of performance introduces no extra physiological data acquisition, saving economical and timing costs.","Title: Coexistence Of Multiple Attractors In An Active Diode Pair Based Chua'S Circuit\nYear: 2018\n\nAbstract: This paper focuses on the coexistence of multiple attractors in an active diode pair based Chua's circuit with smooth nonlinearity. With dimensionless equations, dynamical properties, including boundness of system orbits and stability distributions of two nonzero equilibrium points, are investigated, and complex coexisting behaviors of multiple kinds of disconnected attractors of stable point attractors, limit cycles and chaotic attractors are numerically revealed. The results show that unlike the classical Chua's circuit, the proposed circuit has two stable nonzero node-foci for the specified circuit parameters, thereby resulting in the emergence of multistability phenomenon. Based on two general impedance converters, the active diode pair based Chua's circuit with an adjustable inductor and an adjustable capacitor is made in hardware, from which coexisting multiple attractors are conveniently captured.","Title: A 10-Transistor 65 nm SRAM Cell Tolerant to Single-Event Upsets\nYear: 2016\n\nAbstract: A novel SRAM cell tolerant to single-event upsets (SEUs) is presented in this paper. By adding four more transistors inside, the proposed circuit can obtain higher critical charge at each internal node compared to the conventional 6-transistor (6T) cell. Arrays of 2k-bit capacitance of these two designs were implemented in a 65 nm CMOS bulk technology for comparison purpose. Radiation experiments showed that, at the nominal 1.0 V supply voltage, the proposed cell achieves 47.1 % and 49.3 % reduction in alpha and proton soft error rates (SER) with an area overhead of 37 %.","Title: CRF-LSTM Text Mining Method Unveiling the Pharmacological Mechanism of Off-target Side Effect of Anti-Multiple Myeloma Drugs.\nYear: 2018\n\nAbstract: Off-target effects played a vital role in the pharmacological understanding of drug efficacy and this research aimed to use text mining strategy to curate molecular level information and unveil the mechanism of off-target effect caused by the usage of anti-multiple myeloma (MM) drugs. After training a hybrid CNN-CRF-LSTM neural network upon the training data from TAC 2017 benchmark database, we extracted all of the side effects of 16 anti-MM drugs from drug labels, and combined the results with existed database. Afterwards, gene targets of anti-MM drugs were obtained by using structure similarity, and their related phenotypes were retrieved from Human Phenotype Ontology. Furthermore, linked phenotypes to candidate genes and adverse reaction of known drugs formed a knowledge graph. Through regulation analysis upon intersected phenotypes of drugs and target genes, an off-target effect caused by SLC7A7 was found, which with high possibility unveiled the pharmacological mechanism of side effect after using combination of anti-MM drugs.","Title: BaRC: Backward Reachability Curriculum for Robotic Reinforcement Learning\nYear: 2018\n\nAbstract: Model-free Reinforcement Learning (RL) offers an attractive approach to learn control policies for high dimensional systems, but its relatively poor sample complexity often necessitates training in simulated environments. Even in simulation, goal-directed tasks whose natural reward function is sparse remain intractable for state-of-the-art model-free algorithms for continuous control. The bottleneck in these tasks is the prohibitive amount of exploration required to obtain a learning signal from the initial state of the system. In this work, we leverage physical priors in the form of an approximate system dynamics model to design a curriculum for a model-free policy optimization algorithm. Our Backward Reachability Curriculum (BaRC) begins policy training from states that require a small number of actions to accomplish the task, and expands the initial state distribution backwards in a dynamically-consistent manner once the policy optimization algorithm demonstrates sufficient performance. BaRC is general, in that it can accelerate training of any model-free RL algorithm on a broad class of goal-directed continuous control MDPs. Its curriculum strategy is physically intuitive, easy-to-tune, and allows incorporating physical priors to accelerate training without hindering the performance, flexibility, and applicability of the model-free RL algorithm. We evaluate our approach on two representative dynamic robotic learning problems and find substantial performance improvement relative to previous curriculum generation techniques and naive exploration strategies.","Title: Memristor-Based Canonical Chua's Circuit: Extreme Multistability in Voltage-Current Domain and Its Controllability in Flux-Charge Domain.\nYear: 2018\n\nAbstract: This paper investigates extreme multistability and its controllability for an ideal voltage-controlled memristor emulator-based canonical Chua's circuit. With the voltage-current model, the initial condition-dependent extreme multistability is explored through analyzing the stability distribution of line equilibrium point and then the coexisting infinitely many attractors are numerically uncovered in such a memristive circuit by the attraction basin and phase portraits. Furthermore, based on the accurate constitutive relation of the memristor emulator, a set of incremental flux-charge describing equations for the memristor-based canonical Chua's circuit are formulated and a dimensionality reduction model is thus established. As a result, the initial condition-dependent dynamics in the voltage-current domain is converted into the system parameter-associated dynamics in the flux-charge domain, which is confirmed by numerical simulations and circuit simulations. Therefore, a controllable strategy for extreme multistability can be expediently implemented, which is greatly significant for seeking chaos-based engineering applications of multistable memristive circuits.","Title: Three-Dimensional Memristive Hindmarsh-Rose Neuron Model with Hidden Coexisting Asymmetric Behaviors.\nYear: 2018\n\nAbstract: Since the electrical activities of neurons are closely related to complex electrophysiological environment in neuronal system, a novel three-dimensional memristive Hindmarsh-Rose (HR) neuron model is presented in this paper to describe complex dynamics of neuronal activities with electromagnetic induction. The proposed memristive HR neuron model has no equilibrium point but can show hidden dynamical behaviors of coexisting asymmetric attractors, which has not been reported in the previous references for the HR neuron model. Mathematical model based numerical simulations for hidden coexisting asymmetric attractors are performed by bifurcation analyses, phase portraits, attraction basins, and dynamical maps, which just demonstrate the occurrence of complex dynamical behaviors of electrical activities in neuron with electromagnetic induction. Additionally, circuit breadboard based experimental results well confirm the numerical simulations.","Title: Reach-Avoid Problems Via Sum-Of-Squares Optimization And Dynamic Programming\nYear: 2018\n\nAbstract: Reach-avoid problems involve driving a system to a set of desirable configurations while keeping it away from undesirable ones. Providing mathematical guarantees for such scenarios is challenging but have numerous potential practical applications. Due to the challenges, analysis of reach-avoid problems involves making trade-offs between generality of system dynamics, generality of problem setups, optimality of solutions, and computational complexity. In this paper, we combine sumof- squares optimization and dynamic programming to address the reach-avoid problem, and provide a conservative solution that maintains reaching and avoidance guarantees. Our method is applicable to polynomial system dynamics and to general problem setups, and is more computationally scalable than previous related methods. Through a numerical example involving two single integrators, we validate our proposed theory and compare our method to Hamilton-Jacobi reachability. Having validated our theory, we demonstrate the computational scalability of our method by computing the reach-avoid set of a system involving two kinematic cars.","Title: Simulation Of Metal Droplet Sputtering And Molten Pool On Copper Contact Under Electric Arc\nYear: 2018\n\nAbstract: The micro-mechanism of molten pool and metal droplet sputtering are significant to the material erosion caused by breaking or making arcs especially for high-power switching devices. In this paper, based on Navier-Stokes equations for incompressible viscous fluid and potential equation for electric field, a 2D axially symmetric simplified hydrodynamic model was built to describe the formation of the molten metal droplet sputtering and molten pool under arc spot near electrode region. The melting process was considered by the relationship between melting metal volumetric percentage and temperature, a free surface of liquid metal deformation was solved by coupling moving mesh and the automatic re-meshing. The simulated metal droplet sputtering and molten pool behaviors are presented by the temperature and velocity distribution sequences. The influence mechanism of pressure distribution and heat flux on the formation of molten pool and metal droplet sputtering has been analyzed according to the temperature distribution and sputtering angles. Based on the simulation results, we can distinguish two different models of the molten metal droplet sputtering process: edge ejection and center ejection. Moreover, a new explanation is proposed based on calculated results with arc spot pressure distribution in the form of both unimodal and bimodal. It shows that the arc spot pressure distribution plays an important role in the metal droplet ejected from molten pool, the angle of the molten jet drop can be decreased along with the increment of the arc spot pressure.","Title: Decomposition of Reachable Sets and Tubes for a Class of Nonlinear Systems.\nYear: 2018\n\nAbstract: Reachability analysis provides formal guarantees for performance and safety properties of nonlinear control systems. Here, one aims to compute the backward reachable set (BRS) or tube (BRT)-the set of states from which the system can be driven into a target set at a particular time or within a time interval, respectively. The computational complexity of current approaches scales poorly, making app...","Title: Flux-Charge Analysis Of Initial State-Dependent Dynamical Behaviors Of A Memristor Emulator-Based Chua'S Circuit\nYear: 2018\n\nAbstract: It is known that dynamical behaviors of memristive circuit are significantly affected by its initial states, which are difficult to be explicitly analyzed or controlled in voltage-current domain and have become great obstacles for its potential engineering applications. In this paper, the complex initial state-dependent dynamical behaviors of a physically realized memristive Chua's circuit are detailed and investigated using incremental flux-charge modeling method. This circuit is modeled in terms of incremental flux and charge, in which the original line equilibrium point is converted into some determined equilibrium points relying on the initial states of the dynamic elements. Moreover, the special initial state-dependent behaviors are transformed into system parameter-associated behaviors. Consequently, the detailed influences of each initial state, even the occurrence of hidden oscillations, can readily be theoretically interpreted. Finally, the initial state-dependent behaviors are physically captured and directed in the equivalent realization circuit of the incremental flux-charge model.","Title: Deep Residual Network for Steganalysis of Digital Images\nYear: 2019\n\nAbstract: Steganography detectors built as deep convolutional neural networks have firmly established themselves as superior to the previous detection paradigm – classifiers based on rich media models. Existing network architectures, however, still contain elements designed by hand, such as fixed or constrained convolutional kernels, heuristic initialization of kernels, the thresholded linear unit that mimics truncation in rich models, quantization of feature maps, and awareness of JPEG phase. In this work, we describe a deep residual architecture designed to minimize the use of heuristics and externally enforced elements that is universal in the sense that it provides state-of-the-art detection accuracy for both spatial-domain and JPEG steganography. The key part of the proposed architecture is a significantly expanded front part of the detector that “computes noise residuals” in which pooling has been disabled to prevent suppression of the stego signal. Extensive experiments show the superior performance of this network with a significant improvement, especially in the JPEG domain. Further performance boost is observed by supplying the selection channel as a second channel.","Title: Plug And Play Distributed Model Predictive Control For Heavy Duty Vehicle Platooning And Interaction With Passenger Vehicles\nYear: 2018\n\nAbstract: Heavy duty vehicle (HDV) platooning has been widely accepted as a solution to reduce fuel consumption and traffic congestion. However, the control strategy for HDV platoons interacting with other vehicles is not yet well established. This work presents a new framework for handling the requests of passenger vehicles (PV) plugging in or out of an HDV platoon. It consists of three main steps. First, the basic cruising control of the platoon is achieved by a distributed model predictive control (DMPC) scheme. Second, redesign of controllers ensures the stability of closed loop Plug and Play (P&P) operation. Finally, a transition phase to steady-states guarantees the feasibility of the newly synthesized controllers. Additionally for the plug-in case, we propose a novel approach of Formation Coordinator that determines the optimal location at which the redesigned controller has the best initial feasibility. The performance of the proposed control framework is illustrated on a multi-vehicle platooning system.","Title: Reach-Avoid Games Via Mixed-Integer Second-Order Cone Programming\nYear: 2018\n\nAbstract: Reach-avoid games are excellent proxies for studying many problems in robotics and related fields, with applications including multi-robot systems, human-robot interactions, and safety-critical systems. However, solving reach-avoid games is difficult due to the conflicting and asymmetric goals of agents, and trade-offs between optimality, computational complexity, and solution generality are commonly required. This paper seeks to find attacker strategies in reach-avoid games that reduce computational complexity while retaining solution quality by using a receding horizon strategy. To solve for the open-loop strategy fast enough to enable a receding horizon approach, the problem is formulated as a mixed-integer second-order cone program. This formulation leverages the use of sums-of-squares optimization to provide guarantees that the strategy is robust to all possible defender policies. The method is demonstrated through numerical and hardware experiments.","Title: On Infusing Reachability-Based Safety Assurance Within Probabilistic Planning Frameworks For Human-Robot Vehicle Interactions\nYear: 2018\n\nAbstract: Action anticipation, intent prediction, and proactive behavior are all desirable characteristics for autonomous driving policies in interactive scenarios. Paramount, however, is ensuring safety on the road-a key challenge in doing so is accounting for uncertainty in human driver actions without unduly impacting planner performance. This paper introduces a minimally-interventional safety controller operating within an autonomous vehicle control stack with the role of ensuring collision-free interaction with an externally controlled (e.g., human-driven) counterpart. We leverage reachability analysis to construct a realtime (100 Hz) controller that serves the dual role of (1) tracking an input trajectory from a higher-level planning algorithm using model predictive control, and (2) assuring safety through maintaining the availability of a collision-free escape maneuver as a persistent constraint regardless of whatever future actions the other car takes. A full-scale steer-by-wire platform is used to conduct traffic weaving experiments wherein the two cars, initially side-by-side, must swap lanes in a limited amount of time and distance, emulating cars merging onto/off of a highway. We demonstrate that, with our control stack, the autonomous vehicle is able to avoid collision even when the other car defies the planner's expectations and takes dangerous actions, either carelessly or with the intent to collide, and otherwise deviates minimally from the planned trajectory to the extent required to maintain safety.","Title: Clear Sanctions, Vague Rewards - How China's Social Credit System Currently Defines \"Good\" and \"Bad\" Behavior.\nYear: 2019\n\nAbstract: China's Social Credit System (SCS) or shehui xinyong tixi) is expected to become the first digitally-implemented nationwide scoring system with the purpose to rate the behavior of citizens, companies, and other entities. Thereby, in the SCS, \"good\" behavior can result in material rewards and reputational gain while \"bad\" behavior can lead to exclusion from material resources and reputational loss. Crucially, for the implementation of the SCS, society must be able to distinguish between behaviors that result in reward and those that lead to sanction. In this paper, we conduct the first transparency analysis of two central administrative information platforms of the SCS to understand how the SCS currently defines \"good\" and \"bad\" behavior. We analyze 194,829 behavioral records and 942 reports on citizens' behaviors published on the official Beijing SCS website and the national SCS platform \"Credit China\", respectively. By applying a mixed-method approach, we demonstrate that there is a considerable asymmetry between information provided by the so-called Redlist (information on \"good\" behavior) and the Blacklist (information on \"bad\" behavior). At the current stage of the SCS implementation, the majority of explanations on blacklisted behaviors includes a detailed description of the causal relation between inadequate behavior and its sanction. On the other hand, explanations on redlisted behavior, which comprise positive norms fostering value internalization and integration, are less transparent. Finally, this first SCS transparency analysis suggests that socio-technical systems applying a scoring mechanism","Title: Unique continuation property for the Zakharov-Kuznetsov equation.\nYear: 2019\n\nAbstract: In this paper, we consider the unique continuation property for the Zakharov–Kuznetsov equation posed in a bounded domain. For this purpose, we establish a boundary Carleman estimate for the linear Zakharov–Kuznetsov operator.","Title: Online-Offline Consistency Exploration Based On The Alternating Direction Method Of Multipliers\nYear: 2016\n\nAbstract: Nowadays, online social network has become one of the main tools which people communicate with each other every day. The online users' behavior is a large amount of high dimension data. However, is online and offline behavior the mapping relation? This paper explores whether there is consistency between online and offline behavior using the Alternating Direction Method of Multipliers (ADMM) algorithm. The ADMM is becoming more and more popular recently, due to it can solve the problem of large-scale and complex data sets. ADMM was designed to solve the convex optimization problem. It is an iterative method that minimizes the objective augmented Lagrangian function.","Title: Model Of Network Topic Detection Based On Web Usage Behaviour Mode Analysis And Mining Technology\nYear: 2017\n\nAbstract: This research has caught researchers' wide attention for detecting network topic exactly with the arrival of big data era characterized by semi-structured or unstructured text. This paper proposes a model of network topic detection based on web usage behaviour mode analysis and mining technology taking Web news as object of research. The author elaborates main function and method proposed in this model, which include the analysis module of Web news instance clicking mode, the analysis module of Web news instance retrieval mode, the analysis module of Web news instance seed and the analysis module of similar Web news instance supporting topics. Based on these functions and methods, the author elaborates main algorithm proposed in this model, which include the mining algorithm of Web news seed instances and the mining algorithm of similar Web news instances supporting topics. These functional algorithms have been applied in processing module of model, and focus on how to detect network topic efficiently from a large number of web usage behaviour towards to Web news instances, in order to explore a research method for network topic detection. The process of experimental analysis includes three steps, firstly, the author analyses the precision of topic detection under different method, secondly, the author completes the impact analysis of Web news topic detection quality from the number of Web news instances concerned and seed threshold, finally, the author completes the quality impact analysis of Web news instances mined supporting topic from the number of Web news instances concerned and probability threshold. The results of experimental analysis show the feasibility, validity and superiority of model design and play an important role in constructing topic-focused Web news corpus so as to provide a real-time data source for topic evolution tracking.","Title: Fastrack: A Modular Framework For Fast And Guaranteed Safe Motion Planning\nYear: 2017\n\nAbstract: Fast and safe navigation of dynamical systems through a priori unknown cluttered environments is vital to many applications of autonomous systems. However, trajectory planning for autonomous systems is computationally intensive, often requiring simplified dynamics that sacrifice safety and dynamic feasibility in order to plan efficiently. Conversely, safe trajectories can be computed using more sophisticated dynamic models, but this is typically too slow to be used for real-time planning. We present the new algorithm FaSTrack: Fast and Safe Tracking. A path or trajectory planner using simplified dynamics to plan quickly can be incorporated into the FaSTrack framework, which provides a safety controller for the vehicle along with a guaranteed tracking error bound. This bound captures all possible deviations due to high dimensional dynamics and external disturbances. FaSTrack is modular and can be used with most current path or trajectory planners. We demonstrate this framework using a 10D nonlinear quadrotor model tracking a 3D path obtained from an RRT planner.","Title: Research on Data Visualization in Different Scenarios.\nYear: 2018\n\nAbstract: With the development of computer science, the era of big data has arrived. Facing the new era and new challenges, the traditional analytical methods of problems in various fields have been unable to meet the needs. Data visualization is a rapidly developing discipline, it has significant advantages in analyzing problems, so data visualization shines in the era of big data. As people are very concerned about the fields of energy and environment, we choose to conduct data visualization studies in two areas, energy and the environment. According to the different characteristics of data in different fields, we propose targeted data visualization processes and design data visualization solutions. For energy data, we follow the process of data processing, visualization design, and data visualization. Based on the principle of high efficiency and intuitiveness, we add timeline and a combination of various charts to our design, and finally show a dynamic effect. We also propose a multi-dimensional visual mapping visualization scheme. The scheme can refine and enrich the visual results. For environmental data, we follow the process of goal analysis, data processing, visualization and analysis, the work shows the importance of visualization in information analysis and decision-making.","Title: Dynamical Effects Of Neuron Activation Gradient On Hopfield Neural Network: Numerical Analyses And Hardware Experiments\nYear: 2019\n\nAbstract: Hyperbolic tangent function, a bounded monotone differentiable function, is usually taken as a neuron activation function, whose activation gradient, i.e. gain scaling parameter, can reflect the response speed in the neuronal electrical activities. However, the previously published literatures have not yet paid attention to the dynamical effects of the neuron activation gradient on Hopfield neural network (HNN). Taking the neuron activation gradient as an adjustable control parameter, dynamical behaviors with the variation of the control parameter are investigated through stability analyses of the equilibrium states, numerical analyses of the mathematical model, and experimental measurements on a hardware level. The results demonstrate that complex dynamical behaviors associated with the neuron activation gradient emerge in the HNN model, including coexisting limit cycle oscillations, coexisting chaotic spiral attractors, chaotic double scrolls, forward and reverse period-doubling cascades, and crisis scenarios, which are effectively confirmed by neuron activation gradient-dependent local attraction basins and parameterspace plots as well. Additionally, the experimentally measured results have nice consistency to numerical simulations.","Title: New observation on the key schedule of RECTANGLE\nYear: 2019\n\nAbstract: We evaluate the security of RECTANGLE from the perspective of actual key information (AKI). Insufficient AKI permits the attackers to deduce some subkey bits from some other subkey bits, thereby lowering the overall attack complexity or getting more attacked rounds. By considering the interaction between the key schedule’s diffusion and the round function’s diffusion, we find there exists AKI insufficiency in 4 consecutive rounds for RECTANGLE-80 and 6 consecutive rounds for RECTANGLE-128, although the master key bits achieve complete diffusion in 2 and 4 rounds, respectively. With such weakness of the key schedule, we give a generic meet-in-the-middle attack on 12-round reduced RECTANGLE-128 with only 8 known plaintexts. Moreover, we calculate AKI of variants of RECTANGLE as well as PRESENT. Surprisingly we find that both RECTANGLE-128 and PRESENT-128 with no key schedule involve more AKI than the original one. Based on this finding, we slightly modify the key schedule of RECTANGLE-128. Compared with the original one, this new key schedule matches better with the round function in terms of maximizing AKI. Our work adds more insight to the design of block ciphers’ key schedule.","Title: TTR-Based Rewards for Reinforcement Learning with Implicit Model Priors.\nYear: 2019\n\nAbstract: Model-free reinforcement learning (RL) provides an attractive approach for learning control policies directly in high dimensional state spaces. However, many goal-oriented tasks involving sparse rewards remain difficult to solve with state-of-the-art model-free RL algorithms, even in simulation. One of the key difficulties is that deep RL, due to its relatively poor sample complexity, often requires a prohibitive number of trials to obtain a learning signal. We propose a novel, non-sparse reward function for robotic RL tasks by leveraging physical priors in the form of a time-to-reach (TTR) function computed from an approximate system dynamics model. TTR functions come from the optimal control field and measure the minimal time required to move from any state to the goal. However, TTR functions are intractable to compute for complex systems, so we compute it in a lower-dimensional state space, and then do a simple transformation to convert it into a TTR-based reward function for the MDP in RL tasks. Our TTR-based reward function provides highly-informative rewards that account for system dynamics.","Title: The Development And Performance Evaluation Of Digital Museums Towards Second Classroom Of Primary And Secondary School - Taking Zhejiang Education Technology Digital Museum As An Example\nYear: 2019\n\nAbstract: Currently, visiting museums is one activity that gaining its popularity from primary and secondary school students, which makes museum an important part of second classroom. However, this kind of educational activity is limited by several factors such as transportation, time and space, etc., which result in several defects such as limited visiting efficiency, lacks of evaluation for teaching achievements etc. To solve these problems, we put forward a countermeasure program of digital museums towards second classroom for primary and secondary school students. First, we analyzed the studies of second classroom based on the digital museums both in China and other countries. On the basis of such analysis, we took Zhejiang Education Technology Museum as a template to design and develop Zhejiang Education Technology Digital Museum. Then we used theory of pairing design to study the performance of the traditional museum education and the digital museum education respectively. Finally, we evaluated users' experience of Zhejiang Education Technology Digital Museum by carrying out a questionnaire survey.","Title: Flux-Charge Analysis of Two-Memristor-Based Chua's Circuit: Dimensionality Decreasing Model for Detecting Extreme Multistability\nYear: 2020\n\nAbstract: In this paper, from a new perspective of flux and charge, we present in-depth analyses of two ideal memristor emulators and the fifth-order memristive Chua's circuit constructed based on them. The constitutive flux–charge relations of the two adopted memristor emulators are first formulated, and their initial-dependent characteristics are numerically revealed and experimentally verified. Thereafter, with these two constitutive relations, a third-order dimensionality decreasing flux–charge model for the fifth-order memristive Chua's circuit is constructed, in which five extra constant system parameters are introduced to indicate the initial states of the five dynamic elements. Numerical simulations confirm that this newly constructed model possesses several determined equilibria and maintains the initial-dependent dynamics of the original voltage–current model. Thus, the complex and sensitive initial state-related extreme multistability phenomenon can be deeply explored through theoretical analyses and hardware measurements. It is demonstrated that the sensitive extreme multistability phenomenon becomes detectable in the flux–charge domain, which is efficient for exploring the inner mechanisms and further seeking possible applications of this special phenomenon.","Title: Robust Sequential Trajectory Planning Under Disturbances and Adversarial Intruder\nYear: 2019\n\nAbstract: Provably safe and scalable multivehicle trajectory planning is an important and urgent problem. Although this problem has been studied in the past, there has not been a method that guarantees both goal satisfaction and safety for vehicles with general nonlinear dynamics, while taking into account disturbances and potential adversarial agents, to the best of our knowledge. Hamilton–Jacobi (HJ) reachability is the ideal tool for guaranteeing goal satisfaction and safety under such scenarios, which has been successfully applied to many small-scale problems; however, its direct application in most cases becomes intractable when there are more than two vehicles due to the exponentially scaling computational complexity with respect to system dimension. In this paper, we take advantage of the guarantees provided by HJ reachability and eliminate the computation burden by assigning a strict priority ordering to vehicles under consideration. Under this sequential trajectory planning (STP) scheme, vehicles reserve “space–time” portions in the airspace. The space–time portions guarantee dynamic feasibility, collision avoidance, and optimality of trajectories given the priority ordering. With a computation complexity that scales quadratically when accounting for both disturbances and an intruder, and \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">linearly</italic>\n when accounting for only disturbances, the STP can tractably solve the multivehicle trajectory planning problem for vehicles with general nonlinear dynamics in a practical setting. We demonstrate our theory in representative simulations.","Title: Brain network reconfiguration for language and domain-general cognitive control in bilinguals.\nYear: 2019\n\nAbstract: For bilinguals, language control is needed for selecting the target language during language production. Numerous studies have examined the neural correlates of language control and shown a close relationship between language control and domain-general cognitive control. However, it remains unknown how these brain regions coordinate with each other when bilinguals exert cognitive control over linguistic and nonlinguistic representations. We addressed this gap using an extended unified structural equation modeling (euSEM) approach. Sixty-five Chinese-English bilinguals performed language switching and nonverbal switching tasks during functional magnetic resonance imaging (fMRI) scanning. The results showed that language control was served by a cooperative brain network, including the frontal lobe, the parietal cortex, subcortical areas, and the cerebellum. More importantly, we found that language control recruited more subcortical areas and connections from frontal to subcortical areas compared with domain-general cognitive control, demonstrating a reconfigurable brain network. In addition, the reconfiguration efficiency of the brain network was mainly determined by general cognitive ability but was also mediated by second language (L2) proficiency. These findings provide the first data-driven connectivity model that specifies the brain network for language control in bilinguals and also shed light on the relationship between language control and domain-general cognitive control.","Title: Research On Key Technology Of Web Hierarchical Topic Detection And Evolution Based On Behaviour Tracking Analysis\nYear: 2019\n\nAbstract: In the development background of today's big data era, the research direction of Web hierarchical topic detection and evolution characterized by the semi-structured or unstructured data has caught wide attention for academicians. This paper proposes an idea of Web hierarchical topic detection and evolution based on behaviour tracking analysis taking the network big data as the research object, and expounds main implementation methods, which include the instance analysis of the usage mode, the instance analysis of the seed, the set analysis of similar instance supporting the topics, the set analysis of similar instance supporting the events, the evolution analysis of the event, and expounds the algorithm of Web hierarchical topic detection and evolution based on behaviour tracking analysis. The process of experimental analysis is organized as follows, first of all, the experiment analyses the quality of topic detection, the accuracy rate with the number of instance concerned and the seed threshold variation trend, the accuracy rate with the number of instance concerned and the probability threshold variation trend, secondly, the experiment analyses the quality of topic evolution, the accuracy rate with the variation trend of parameter adjustment, the accuracy rate with the number of instance concerned and the similar threshold variation trend, finally, the experiment analyses the time consuming to solve main research problem under different method, the qualitative result of topic detection and evolution under different data set. The results of experimental analysis show the idea is feasible, verifiable and superior, which plays a major role in reconfiguring Web hierarchical topic corpus and providing an intelligent big data warehouse for the network information evolution application.","Title: Reference Channels for Steganalysis of Images with Convolutional Neural Networks.\nYear: 2019\n\nAbstract: When available, reference signals may dramatically improve the accuracy of steganalysis. Particularly powerful reference signals are embedding invariants that exist when the steganographic algorithm swaps values from small disjoint subsets of the cover elements' dynamic range, such as, but not limited to, embedding schemes utilizing least significant bit replacement. This paper describes a general method how to prepare such reference signals for a certain type of embedding operations, and incorporate them in detectors built as convolutional networks to improve their detection accuracy. The beneficial effect of reference signals is shown experimentally in both the spatial and especially JPEG domain, on model-based steganography and a generic LSB flipper with and without stochastic restoration of the histogram (OutGuess).","Title: Hybrid State Variable Incremental Integral for Reconstructing Extreme Multistability in Memristive Jerk System with Cubic Nonlinearity.\nYear: 2019\n\nAbstract: Memristive system with infinitely many equilibrium points has attracted much attention for the generation of extreme multistability, whose initial-dependent dynamics can be interpreted in a reduced-order model through incremental integral transformation of state variables. But, the memristive system with any extra nonlinear terms besides the memristor ones cannot be handled directly using this method. In addition, the transformed state variables could be divergent due to the asymmetry of the original system. To solve these problems, a hybrid state variable incremental integral (HSVII) method is proposed in this paper. With this method, the extreme multistability in a four-dimensional (4D) memristive jerk system with cubic nonlinearity is successfully reconstituted in a three-dimensional (3D) model and the divergent state variables are eliminated through ingenious linear state variable mapping. Thus, mechanism analysis and physical control of the special extreme multistability can readily be performed. A hardware circuit is finally designed and fabricated, and the theoretical and numerical results are verified by the experimental measurements. It is demonstrated that this HSVII method is effective for the analysis of multistable system with high-order nonlinearities.","Title: Blacklists and Redlists in the Chinese Social Credit System: Diversity, Flexibility, and Comprehensiveness\nYear: 2021\n\nAbstract: The Chinese Social Credit System (SCS) is a novel digital socio-technical credit system. The SCS aims to regulate societal behavior by reputational and material devices. Scholarship on the SCS has offered a variety of legal and theoretical perspectives. However, little is known about its actual implementation. Here, we provide the first comprehensive empirical study of digital blacklists (listing \"bad\" behavior) and redlists (listing \"good\" behavior) in the Chinese SCS. Based on a unique data set of reputational blacklists and redlists in 30 Chinese provincial-level administrative divisions (ADs), we show the diversity, flexibility, and comprehensiveness of the SCS listing infrastructure. First, our results demonstrate that the Chinese SCS unfolds in a highly diversified manner: we find differences in accessibility, interface design and credit information across provincial-level SCS blacklists and redlists. Second, SCS listings are flexible. During the COVID-19 outbreak, we observe a swift addition of blacklists and redlists that helps strengthen the compliance with coronavirus-related norms and regulations. Third, the SCS listing infrastructure is comprehensive. Overall, we identify 273 blacklists and 154 redlists across provincial-level ADs. Our blacklist and redlist taxonomy highlights that the SCS listing infrastructure prioritizes law enforcement and industry regulations. We also identify redlists that reward political and moral behavior. Our study substantiates the enormous scale and diversity of the Chinese SCS and puts the debate on its reach and societal impact on firmer ground. Finally, we initiate a discussion on the ethical dimensions of data-driven research on the SCS.","Title: Integrated Optimization of Train Speed Profile and Timetable Considering the Location of Substations\nYear: 2021\n\nAbstract: Adjusting the timetable and speed profile of trains can bring significant reduction in energy consumption, which is almost zero cost to the subway operating company. This paper proposes an integrated optimization method for a single train, to simultaneously obtain the optimal speed profile and the interstation trip time distribution of the whole journey by dynamic programming (DP). With modeling t...","Title: Optimal shape morphing control of 4D printed shape memory polymer based on reinforcement learning\nYear: 2022\n\nAbstract: 4D printing technology, as a new generation of Additive Manufacturing methods, enables printed objects to further change their shapes or other properties upon external stimuli. One main category of 4D printing research is 4D printed thermal Shape Memory Polymer (SMP). Its morphing process has large time delay, is nonlinear time variant, and susceptible to unpredictable disturbances. Reaching an arbitrary position with high precision is an active research question. This paper applies the Reinforcement Learning (RL) method to develop an optimal control method to perform closed loop control of the SMP actuation. Precise and prompt shape morphing is achieved compared with previous control methods using a PI controller. The training efforts of RL are further reduced by simplifying the optimal control policy using the structural property of the prior trained results. Customized protective visors against COVID-19 are fabricated using the proposed control method.","Title: Discrete Memristor Hyperchaotic Maps\nYear: 2021\n\nAbstract: Regarding as a basic circuit component with special nonlinearity, memristor has been widely applied in chaotic circuits and neuromorphic circuits. However, discrete memristor (DM) has not been received much attention, yet. To this end, this paper reports a general DM model and its unified mapping model. Using the general DM model, four representations of DMs are given and their pinched hysteresis ...","Title: Coexisting Infinitely Many Nonchaotic Attractors In A Memristive Weight-Based Tabu Learning Neuron\nYear: 2021\n\nAbstract: Memristive synaptic weight is a changeable connection synaptic weight. It reflects the self-adaption physical processing in biological neurons. To study its dynamical effect, this paper presents a memristive synaptic weight-based tabu learning neuron model. It is constructed by replacing the resistive self-connection synaptic weight in the tabu learning neuron with a memristive self-connection synaptic weight. The equilibrium point of the memristive tabu learning model is time-varying and switches between no equilibrium state and line equilibrium state with the change of the external current. Particularly, the stability of the line equilibrium state closely relies on the initial state of the memristor, resulting in the emergence of coexisting infinitely many nonchaotic attractors. By employing the bifurcation plots, Lyapunov exponents, and phase plots, this paper numerically reveals the initial state-switched coexisting bifurcation behaviors and initial state-relied extreme multistability, and thereby discloses the coexisting infinitely many nonchaotic attractors composed of mono-periodic, multiperiodic, and quasi-periodic orbits. In addition, PSIM circuit simulations and printed-circuit board-based experiments are executed and the coexisting infinitely many nonchaotic attractors are realized physically. The results well verify the numerical simulations.","Title: Initial-condition-switched boosting extreme multistability and mechanism analysis in a memcapacitive oscillator\nYear: 2021\n\nAbstract: Extreme multistability has seized scientists' attention due to its rich diversity of dynamical behaviors and great flexibility in engineering applications. In this paper, a four-dimensional (4D) memcapacitive oscillator is built using four linear circuit elements and one nonlinear charge-controlled memcapacitor with a cosine inverse memcapacitance. The 4D memcapacitive oscillator possesses a line equilibrium set, and its stability periodically evolves with the initial condition of the memcapacitor. The 4D memcapacitive oscillator exhibits initial-condition-switched boosting extreme multistability due to the periodically evolving stability. Complex dynamical behaviors of period doubling/halving bifurcations, chaos crisis, and initial-condition-switched coexisting attractors are revealed by bifurcation diagrams, Lyapunov exponents, and phase portraits. Thereafter, a reconstructed system is derived via integral transformation to reveal the forming mechanism of the initial-condition-switched boosting extreme multistability in the memcapacitive oscillator. Finally, an implementation circuit is designed for the reconstructed system, and Power SIMulation (PSIM) simulations are executed to confirm the validity of the numerical analysis.","Title: Real-Time Hamilton-Jacobi Reachability Analysis of Autonomous System With An FPGA\nYear: 2021\n\nAbstract: Hamilton-Jacobi (HJ) reachability analysis is a powerful technique used to verify the safety of autonomous systems. HJ reachability is ideal for analysing nonlinear systems with disturbances and flexible set representations. A drawback to this approach is that it suffers from the curse of dimensionality, which prevents real-time deployment on safety-critical systems. In this paper, we show that a customized hardware design on an Field Programmable Gate Array (FPGA) could accelerate 4D grid-based HJ reachability analysis up to 14 times compared to an optimized implementation and 103 times compared to state-of-the-art MATLAB toolboxes on a 16-thread CPU. Because of this, we are able to achieve guaranteed real-time collision avoidance in dynamic environments that abruptly change with a 4D car model by re-solving the HJ partial differential equation (PDE) at a frequency of 4Hz on an FPGA. Our design can overcome the complex data access pattern while taking advantage of the parallel nature of the computations for solving the HJ PDE. The low latency of our computation is consistent, which is crucial for safety-critical systems. The methodology presented here is without loss of generality: it can potentially be applied to different systems dynamics, and moreover, leveraged for higher dimensional systems. We validate our approach in real world collision avoidance experiments with a robot car in a changing environment. We also provide the code of our hardware design and an AWS AFI image.","Title: A Multimodal and Hybrid Framework for Human Navigational Intent Inference\nYear: 2021\n\nAbstract: Understanding human navigational intent is essential for robots to be able to interact with and navigate around humans safely and naturally. Current methods typically perform inference through only one mode of perception such as human motion trajectory, and a single theoretical framework such as a learning-based or classical approach. In contrast, this paper studies prediction of human navigational intent using multimodal perception within a hybrid framework. Our framework consists of two modules: a) a learning-based prediction module to predict a human's future goal position, and b) a classical control theory-inspired reconstruction module to reconstruct a possible future trajectory or a set of possible future positions using the predicted future goal position. For the prediction module, we propose an end-to-end LSTM-CNN hybrid neural network for predicting a human's future position in the real world, given human motion, human body pose and head orientation. This visual information from an egocentric perspective is used to make predictions of a human's future position in world space, essential for robotic navigation algorithms and planning. In the reconstruction module, we present two control theoretic methods to reconstruct possible future trajectories of human: trajectory generation for differentially flat system and reachability analysis. We evaluate the performance of our framework on a newly collected dataset called SFU-Store-Nav. Experimental results reveal that our method outperforms various baselines especially when a relatively small amount of data is available.","Title: Finite-Time Synchronization for Fuzzy Delayed Neutral-Type Inertial Bam Neural Networks Via the Figure Analysis Approach\nYear: 2022\n\nAbstract: This paper focuses on the finite-time synchronization for fuzzy delayed neutral-type inertial BAM neural networks. Without making the variable transformation, the inertial system was analyzed directly. By applying integral inequality techniques and the figure analysis approach, some novel criteria are achieved to assure the finite-time synchronization between the drive system and the response system. The inequalities used in our paper are different from these in the existing papers. The figure analysis approach used to research finite-time synchronization in our paper is a completely novel study approach.","Title: Double-Vector Model-Free Predictive Control Method for Voltage Source Inverter With Visualization Analysis\nYear: 2022\n\nAbstract: Strong parameter dependence and large current ripple are two shortcomings that obstruct the development of model predictive control for voltage source inverters (VSIs). To solve these problems, in this article,a double-vector model-free predictive control (MFPC) method for VSI with visualization analysis is proposed. First, the ultralocal model of the VSI is established and a full-order sliding mo...","Title: Piecewise-Linear Simplification for Adaptive Synaptic Neuron Model\nYear: 2022\n\nAbstract: Adaptive synaptic neuron model involves complex activation functions. These nonlinearities lead to complicated hardware implementations, which greatly hinder neuron-based applications. To effectively solve this issue, a piecewise-linear (PWL) activation function with simplified circuit implementation is presented for the adaptive synaptic neuron model in this brief. With this neuron model, the stability evolution mechanism of the equilibrium state is analyzed and the parameter- and initial condition-related neuron dynamics are numerically explored. Afterwards, an analog circuit is designed and manually made using commercially available components. The phase trajectories captured by the hardware experiments verify the feasibility of the PWL activation function. Thus, such a PWL simplification shows superiority in emulating neuron dynamics.","Title: Applications of affordance and cognitive ergonomics in virtual design: A digital camera as an illustrative case\nYear: 2022\n\nAbstract: Affordance-based design (ABD) plays an important role in identifying interactions, especially effortless ones, between users and artifacts. Cognitive ergonomics extends our understanding of this effortless interaction. This study combines the two design methodologies together in order to reduce cognitive friction in using digital products. The design process of a compact digital camera is selected as a case study that includes the design of the physical shape for a camera and of its user interface. In designing a product shape, a design toolbox was developed that integrated a modified multi-objective genetic algorithm and the ABD, which was named as affordance-based interactive genetic algorithm. Using this toolbox and interactive user feedback, the camera design evolves toward a product that better satisfies the users. User interfaces (UIs) including linear and elliptic layouts were subsequently designed based on cognitive ergonomics. A predictive tool of UI, the Cog Tool, was used to evaluate the performance of skilled users on a given task by correlating the overall task completion time. Finally, this research has the potential to not only effectively address the shortcomings of the design of consumer electronics but also enrich the generation of design solutions during the preliminary design phase of such products.","Title: Memristor-Based Hyperchaotic Maps and Application in Auxiliary Classifier Generative Adversarial Nets\nYear: 2022\n\nAbstract: With the nonlinearity and plasticity, memristors are widely used as nonlinear devices for chaotic oscillations or as biological synapses for neuromorphic computations. But discrete memristors (DMs) and their coupling maps have not received much attention, yet. Using a DM model, this article presents a general three-dimensional discrete memristor-based (3-D-DM) map model. By coupling the DM with fo...","Title: Analog/Digital Multiplierless Implementations for Nullcline-Characteristics-Based Piecewise Linear Hindmarsh-Rose Neuron Model\nYear: 2022\n\nAbstract: Multipliers are essential in implementing nonlinear neuron models, but they take huge implementation costs. Many multiplierless fitting schemes have been proposed to simplify the implementation of nonlinearities in neuron models. To optimize these schemes, this paper presents a nullcline-characteristics- based piecewise linear (NC-PWL) fitting scheme for multiplierless implementations of Hindmarsh-Rose (HR) neuron model. This NC-PWL fitting scheme uses as few line segments as possible to approximate the critical nonlinearity characteristics of the local nullclines. A NC-PWL HR neuron model that reproduces diverse firing patterns of the original one is successfully established. Using off-the-shelf low-cost components, an analog multiplierless circuit is designed for this fitting model and welded on print circuit board (PCB). Meanwhile, by logical shift method, a digital multiplierless circuit with low resource consumption is developed for this fitting model on field-programmable gate array (FPGA) platform. Experimental results of the analog and digital multiplierless hardware implementations verify the numerical simulations and show the simplicity and feasibility of the presented fitting scheme.","Title: Towards Inclusive HRI: Using Sim2Real to Address Underrepresentation in Emotion Expression Recognition.\nYear: 2022\n\nAbstract: Robots and artificial agents that interact with humans should be able to do so without bias and inequity, but facial perception systems have notoriously been found to work more poorly for certain groups of people than others. In our work, we aim to build a system that can perceive humans in a more transparent and inclusive manner. Specifically, we focus on dynamic expressions on the human face, which are difficult to collect for a broad set of people due to privacy concerns and the fact that faces are inherently identifiable. Furthermore, datasets collected from the Internet are not necessarily representative of the general population. We address this problem by offering a Sim2Real approach in which we use a suite of 3D simulated human models that enables us to create an auditable synthetic dataset covering 1) underrepresented facial expressions, outside of the six basic emotions, such as confusion; 2) ethnic or gender minority groups; and 3) a wide range of viewing angles that a robot may encounter a human in the real world. By augmenting a small dynamic emotional expression dataset containing 123 samples with a synthetic dataset containing 4536 samples, we achieved an improvement in accuracy of 15% on our own dataset and 11% on an external benchmark dataset, compared to the performance of the same model architecture without synthetic training data. We also show that this additional step improves accuracy specifically for racial minorities when the architecture's feature extraction weights are trained from scratch.","Title: PolarDB-X: An Elastic Distributed Relational Database for Cloud-Native Applications\nYear: 2022\n\nAbstract: Cloud computing is on the rise, which promotes new breeds of database systems to accommodate the cloud environment. The development of cloud-native databases reveals three trends. One is the adoption of multi-datacenter (DC) deployment to survive the downtime of any single site. Another is the separation of computation and storage resources to achieve higher elasticity and scalability. The last is the support of HTAP to eliminate data redundancy and system complexity from heterogeneous databases. To cater to these trends, we design a distributed relational database called PolarDB-X, which is built on top of the cloudnative database PolarDB. It hence inherits many cloud-native features, such as multi-datacenter deployment and elasticity. To achieve cross-DC capability, it leverages Paxos and hybrid logical clock to achieve durability and snapshot-isolation consistency with low coordination costs. For resource elasticity, since the underlying PolarDB supports rapid migration of tenants between nodes, PolarDB-X can quickly scale the cluster to cope with a sudden traffic increase. For HTAP support, with the help of read replicas and a HTAP executor, PolarDB-X can improve the latency and parallelism of analytical queries without impacting concurrently-running TP workloads. Using its MPP engine and an in-memory column index, the efficiency of analytical queries can be further enhanced. PolarDB-X is now a cloud database service at Alibaba Cloud. We have learned many useful lessons from its development and operation, and have incorporated those into our design and analysis.","Title: Real-time Mapping of Multi-Floor Buildings Using Elevators\nYear: 2022\n\nAbstract: This paper discusses the creation of a map of multi-floor buildings using elevators in autonomous and manual driving modes. Two disadvantages of existing Simultaneous Localization And Mapping (SLAM) algorithms are inability to detect elevation change and drift inside reflective environments such as many modern elevators. Therefore, we integrate the LeGO-LOAM SLAM algorithm with air pressure data collected by a barometric pressure sensor to create a map of a multi-story building in real-time without losing track of robot’s movement inside an elevator. To achieve this, we developed an elevator detection module to detect elevators using a depth camera and locate them in floor maps. In autonomous driving mode, after exploring and mapping one floor, the robot autonomously navigates to the detected elevator, takes it to another floor, and starts mapping the new floor without losing track of the robot’s position despite sudden changes in the environment during this process. The manual driving mode is subsequently added to evaluate the performance of the system and the accuracy of the generated map. The experimental results show that the proposed algorithm is capable of mapping multiple floors autonomously and manually with minimal drift."],"string":"[\n \"Title: Progressive cut\\nYear: 2006\\n\\nAbstract: Recently, interactive image cutout technique becomes prevalent for image segmentation problem due to its easy-to-use nature. However, most existing stroke-based interactive object cutout system did not consider the user intention inherent in the user interaction process. Strokes in sequential steps are treated as a collection rather than a process, and only the color information of the additional stroke is used to update the color model in the graph cut framework. Accordingly, unexpected fluctuation effect may occur during the process of interactive object cutout. In fact, each step of user interaction reflects the user's evaluation of previous result and his/her intention. By analyzing the user's intention behind the interaction, we propose a progressive cut algorithm, which explicitly models the user's intention into a graph cut framework for the object cutout task. Three aspects of user intention are utilized: 1) the color of the stroke indicates the kind of change s/he expects, 2) the location of the stroke indicates the region of interest, 3) the relative position between the stroke and the previous result indicates the segmentation error. By incorporating such information into the cutout system, the new algorithm removes the unexpected fluctuation effect of existing stroke-based graph-cut methods, and thus provides the user a more controllable result with fewer strokes and faster visual feedback. Experiments and user study show the strength of progressive cut in accuracy, speed, controllability, and user experience.\",\n \"Title: Directed graph embedding\\nYear: 2007\\n\\nAbstract: In this paper, we propose the Directed Graph Embedding (DGE) method that embeds vertices on a directed graph into a vector space by considering the link structure of graphs. The basic idea is to preserve the locality property of vertices on a directed graph in the embedded space. We use the transition probability together with the stationary distribution of Markov random walks to measure such locality property. It turns out that by exploring the directed links of the graph using random walks, we can get an optimal embedding on the vector space that preserves the local affinity which is inherent in the directed graph. Experiments on both synthetic data and real-world Web page data are considered. The application of our method to Web page classification problems gets a significant improvement comparing with state-of-art methods.\",\n \"Title: Qualitative assessment of intrinsic mode functions of empirical mode decomposition\\nYear: 2008\\n\\nAbstract: The 'empirical mode decomposition' (EMD) method has been recently proposed to deal with nonlinear and non- stationary data, which decomposes signals into 'well-behaved' intrinsic mode functions (IMFs). An assessment on the qualitative performance of the EMD method in terms of the degree of signal nature preservation of individual IMF is provided. This is archived by means of the recently proposed signal characterisation method, based upon examining the signal predicability in phase space. It is shown that the first IMF always performs best in terms of signal nature preserving. Simulation results on both linear and nonlinear benchmark signals support the analysis.\",\n \"Title: A Novel Channel Assignment Algorithm for Multicast in Multi-radio Wireless Mesh Networks\\nYear: 2007\\n\\nAbstract: With the development of Internet, many new applications with obvious multicast character come forth and become popular, which increase the importance of multicast in Internet especially in wireless access networks where the bandwidths of networks are very limited. In this paper, we consider the problem of channel assignment for multicast in multi-radio wireless mesh networks (WMNs), which have not been studied up to now. We propose a novel channel assignment strategy called UCAS based on unidirectional link model, and give an efficient greedy vertex coloring algorithm called BFVC. Finally, the results of simulations demonstrate the efficiency of the algorithms presented in this paper.\",\n \"Title: A Novel Tool for Sequential Fusion of Nonlinear Features: A Sleep Psychology Application\\nYear: 2006\\n\\nAbstract: A framework for automated scoring of sleep stages during afternoon naps of healthy humans is introduced. This is achieved by sequential fusion of nonlinear features extracted from three physiological channels: the electroencephalogram (EEG), electrooculogram (EOG) and respiratory trace (RES). These features are generated by means of the recently introduced \\\"delay vector variance\\\" (DVV) method which examines local predictability of a signal in phase space. The analysis is accompanied by a set of comprehensive simulations, supporting the approach\",\n \"Title: An automated vision system for container-code recognition\\nYear: 2012\\n\\nAbstract: Automatic container-code recognition is of great importance to the modern container management system. Similar techniques have been proposed for vehicle license plate recognition in past decades. Compared with license plate recognition, automatic container-code recognition faces more challenges due to the severity of nonuniform illumination and invalidation of color information. In this paper, a computer vision based container-code recognition technique is proposed. The system consists of three function modules, namely location, isolation, and character recognition. In location module, we propose a text-line region location algorithm, which takes into account the characteristics of single character as well as the spatial relationship between successive characters. This module locates the text-line regions by using a horizontal high-pass filter and scanline analysis. To resolve nonuniform illumination, a two-step procedure is applied to segment container-code characters, and a projection process is adopted to isolate characters in the isolation module. In character recognition module, the character recognition is achieved by classifying the extracted features, which represent the character image, with trained support vector machines (SVMs). The experimental results demonstrate the efficiency and effectiveness of the proposed technique for practical usage.\",\n \"Title: Icruiser: An Improved Approach For Concurrent Heap Buffer Overflow Monitoring\\nYear: 2014\\n\\nAbstract: Heap buffer overflow has been extensively studied for many years, but it remains a severe threat to software security. Previous solutions suffer from limitations in that: 1) Some methods need to modify the target programs; 2) Most methods could impose considerable performance overhead. In this paper, we present iCruiser, an efficient heap buffer overflow monitoring system that uses the multi-core technology. Our system is compatible with existing programs, and it can detect the heap buffer overflows concurrently. Compared with the latest heap protection systems, our approach can achieves stronger security guarantees. Experiments show that iCruiser can detect heap buffer overflow attacks effectively with a little performance overhead.\",\n \"Title: Real-time motion effect enhancement based on fluid dynamics in figure animation\\nYear: 2011\\n\\nAbstract: In fast figure animation, motion blur is often employed to generate fantastic effects of figure motion, for exaggerating the atmosphere one wants to convey. In the previous works for long time, the solution based on certain kind of image blending in terms of hardware or software, was simply adopted. In order to provide high standard of motion blur effect, methods based on 3D geometry of the motion figure with global illumination become gradually in demand. However, the computation cost to meet such demand is very high and it is hard to achieve real time rendering. In our work, a novel 3D geometric approach of real-time motion effect is proposed. By the approach, a special effect along the motion trajectory based on fluid simulation is combined with the volumetric motion blur. Besides, in order to avoid the redundant calculation of each frame and break the limitation of trajectory generation, we decompose the motion trajectory and employ multi-pass geometry rendering to achieve geometry instancing for reuse. In the pipeline, we separate motion tracking and fluid solution, to support various fluid effects flexibly. As our algorithm is constructed in the context of GPU geometry shading in parallel, high efficiency of computation is guaranteed while realizing gorgeous rendering. As a result, real time rendering including the motion blur effect is achieved.\",\n \"Title: Efficient Shellcode Detection On Commodity Hardware\\nYear: 2013\\n\\nAbstract: As more and more software vulnerabilities are exposed, shellcode has become very popular in recent years. It is widely used by attackers to exploit vulnerabilities and then hijack program's execution. Previous solutions suffer from limitations in that: 1) Some methods based on static analysis may fail to detect the shellcode using obfuscation techniques. 2) Other methods based on dynamic analysis could impose considerable performance overhead. In this paper, we propose Lemo, an efficient shellcode detection system. Our system is compatible with commodity hardware and operating systems, which enables deployment. To improve the performance of our system, we make use of the multi-core technology. The experiments show that our system can detect shellcode efficiently.\",\n \"Title: Moving K-Nearest Neighbor Query over Obstructed Regions\\nYear: 2010\\n\\nAbstract: In recent years, there has been a growing need for location-based services (LBS), ranging from resource tracking to personal life assistance. The Moving k Nearest Neighbor (MkNN) query is a main problem in the LBS area, which retrieves the top k nearest neighbors while the query consumer moves. Considerable attention is attracted to this query type and a large number of studies are proposed recently. Most of these studies focus on ideal Euclidean plane where any two points are visible. In this paper, we propose a method to process MkNN queries in areas with obstacles, which is more realistic. We propose the obstacle-free safe region (OSR) concept within which a query point has the same kNN. No additional processing is required when the query consumer moves inside one OSR. Several novel properties are also introduced and employed in our efficient MkNN processing algorithm. Our experimental results show that our approach handles the MkNN queries with high accuracy and works efficiently.\",\n \"Title: Evaluating probabilistic spatial-range closest pairs queries over uncertain objects\\nYear: 2011\\n\\nAbstract: In emerging applications such as location-based service (LBS), the values of spatial database items are naturally uncertain. This paper focuses on the problem of finding probabilistic closest pairs between two uncertain spatial datasets in a given range, namely, probabilistic spatialrange closest pair (PSRCP) query. In particular, given two uncertain spatial datasets which contain uncertain objects modeled by a set of sampled instances, a PSRCP query retrieves the pairs that satisfy the query with probabilities higher than a given threshold. Several pruning strategies are proposed to filter the objects that cannot constitute an answer, which can significantly improve the query performance. Extensive experiments are performed to examine the effectiveness of our methods.\",\n \"Title: Exploiting nonlinearity in adaptive signal processing\\nYear: 2007\\n\\nAbstract: Quantitative performance criteria for the analysis of machine learning architectures and algorithms have been long established. However, the qualitative performance criteria, e.g., nonlinearity assessment, are still emerging. To that end, we employ some recent developments in signal characterisation and derive criteria for the assessment of the changes in the nature of the processed signal. In addition, we also propose a novel online method for tracking the system nonlinearity. A comprehensive set of simulations in both the linear and nonlinear settings and their combination supports the analysis.\",\n \"Title: Progressive Cut: An Image Cutout Algorithm that Models User Intentions\\nYear: 2007\\n\\nAbstract: To give users more control over image segmentation and extraction, we propose the progressive-cut algorithm, which explicitly models the user's intention in a graph-cut framework. Because we incorporate three aspects of user intention into an object cutout system, our algorithm lets users work with fewer strokes, achieving faster and more accurate visual feedback.\",\n \"Title: Spatial query processing in road networks for wireless data broadcast\\nYear: 2013\\n\\nAbstract: Recently, wireless broadcast environments have attracted significant attention due to its high scalability to broadcast information to a large number of mobile subscribers. It is especially a promising and desirable dissemination method for the heavily loaded environment where a great number of the same type of requests are sent from the users. There have been many studies on processing spatial queries via broadcast model recently. However, not much attention is paid to the spatial queries in road networks on wireless broadcast environments. In this paper, we focus on three common types of spatial queries, namely, k nearest neighbor (kNN) queries, range queries and reverse nearest neighbor (RNN) queries in spatial networks for wireless data broadcast. Specially, we propose a novel index for spatial queries in wireless broadcast environments (ISW). With the reasonable organization and the effectively pre-computed bounds, ISW provides a powerful framework for spatial queries. Furthermore, efficient algorithms are designed to cope with kNN, range and RNN queries separately based on ISW. The search space can be obviously reduced and subsequently the client can download as less as possible data for query processing, which can conserve the energy while not significantly influence the efficiency. The detailed theory analysis of cost model and the experimental results are presented for verifying the efficiency and effectiveness of ISW and our methods.\",\n \"Title: A practical system of keyphrase extraction for web pages\\nYear: 2005\\n\\nAbstract: Keyphrases can be used to facilitate Web users grasping the main topic(s) of a Web page. We present a practical system of automatic keyphrase extraction for Web pages. In this system, a regression model was first trained based on a set of human-labeled documents. Then it was used to extract keyphrases from new pages automatically. This paper makes three contributions. First, the structure information in a Web page was investigated for keyphrase extraction task. Second, the query log data associated with a Web page collected by a search engine server were used to help keyphrase extraction. Third, a method was put forward in this paper in order to evaluate the similarity of phrases.\",\n \"Title: Joint optimization of product family configuration and scaling design by Stackelberg game.\\nYear: 2014\\n\\nAbstract: •Currently module configuration and scaling design are treated as two separate decisions.•A significant finding that these two problems are coupled in nature, leading to joint optimization.•A novel application of Stackelberg game models to the product family design field.•Synthesis of unique context of product families within a coherent equilibrium decision framework.•Comparative study reveals that our bilevel model is advantageous over the existing practice.\",\n \"Title: Sensor noise camera identification: countering counter-forensics\\nYear: 2010\\n\\nAbstract: In camera identification using sensor noise, the camera that took a given image can be determined with high certainty by establishing the presence of the camera's sensor fingerprint in the image. In this paper, we develop methods to reveal counter-forensic activities in which an attacker estimates the camera fingerprint from a set of images and pastes it onto an image from a different camera with the intent to introduce a false alarm and, in doing so, frame an innocent victim. We start by classifying different scenarios based on the sophistication of the attacker's activity and the means available to her and to the victim, who wishes to defend herself. The key observation is that at least some of the images that were used by the attacker to estimate the fake fingerprint will likely be available to the victim as well. We describe the so-called \\\"triangle test\\\" that helps the victim reveal attacker's malicious activity with high certainty under a wide range of conditions. This test is then extended to the case when none of the images that the attacker used to create the fake fingerprint are available to the victim but the victim has at least two forged images to analyze. We demonstrate the test's performance experimentally and investigate its limitations. The conclusion that can be made from this study is that planting a sensor fingerprint in an image without leaving a trace is significantly more difficult than previously thought.\",\n \"Title: An assessment of qualitative performance of machine learning architectures: modular feedback networks.\\nYear: 2008\\n\\nAbstract: A framework for the assessment of qualitative performance of machine learning architectures is proposed. For generality, the analysis is provided for the modular nonlinear pipelined recurrent neural network (PRNN) architecture. This is supported by a sensitivity analysis, which is achieved based upon the prediction performance with respect to changes in the nature of the processed signal and by utilizing the recently introduced delay vector variance (DVV) method for phase space signal characterization. Comprehensive simulations combining the quantitative and qualitative analysis on both linear and nonlinear signals suggest that better quantitative prediction performance may need to be traded in order to preserve the nature of the processed signal, especially where the signal nature is of primary importance (biomedical applications).\",\n \"Title: An online method for detecting nonlinearity within a signal\\nYear: 2006\\n\\nAbstract: A novel method for online analysis of the changes in signal modality is proposed. This is achieved by tracking the dynamics of the mixing parameter within a hybrid filter rather than the actual filter performance. An implementation of the proposed hybrid filter using a combination of the Least Mean Square (LMS) and the Generalised Normalised Gradient Descent (GNGD) algorithms is analysed and the potential of such a scheme for tracking signal nonlinearity is highlighted. Simulations on linear and nonlinear signals in a prediction configuration support the analysis. Biological applications of the approach have been illustrated on EEG data of epileptic patients.\",\n \"Title: Fusion of state space and frequency-domain features for improved microsleep detection\\nYear: 2005\\n\\nAbstract: A novel approach for Microsleep Event detection is presented. This is achieved based on multisensor electroencephalogram (EEG) and electrooculogram (EOG) measurements recorded during an overnight driving simulation task. First, using video clips of the driving, clear Microsleep (MSE) and Non-Microsleep (NMSE) events were identified. Next, segments of EEG and EOG of the selected events were analyzed and features were extracted using Power Spectral Density and Delay Vector Variance. The so obtained features are used in several combinations for MSE detection and classification by means of populations of Learning Vector Quantization (LVQ) networks. Best classification results, with test errors down to 13%, were obtained by a combination of all the recorded EEG and EOG channels, all features, and with feature relevance adaptation using Genetic Algorithms.\",\n \"Title: Isoperimetric cut on a directed graph\\nYear: 2010\\n\\nAbstract: In this paper, we propose a novel probabilistic view of the spectral clustering algorithm. In our framework, the spectral clustering algorithm can be viewed as assigning class labels to samples to minimize the Bayes classification error rate by using a kernel density estimator (KDE). From this perspective, we propose to construct directed graphs using variable bandwidth KDEs. Such a variable bandwidth KDE based directed graph has the advantage that it encodes the local density information of the data in the graph edge weights. In order to cluster vertices of the directed graph, we develop a directed graph partitioning algorithm which optimizes a random walk isoperimetric ratio. The partitioning result can be obtained efficiently by solving a system of linear equations. We have applied our algorithm to several benchmark data sets and obtained promising results.\",\n \"Title: On Nonlinear Modular Neural Filters\\nYear: 2005\\n\\nAbstract: An assessment of the performance of the pipelined recurrent neural network (PRNN) is provided from two aspects, a quantitative one based on the prediction gain and a qualitative one based on examining the changes in the nature of the processed signal. This is achieved by means of the recently introduced 'Delay Vector Variance' (DVV) method for phase space signal characterisation. A comprehensive analysis of this approach on both linear and nonlinear benchmark signals suggests that the PRNN not only outperforms a single recurrent neural network (RNN) in terms of the prediction gain but also has better or similar performance in terms of preserving the nature of the processed signal.\",\n \"Title: Feature Fusion for the Detection of Microsleep Events\\nYear: 2007\\n\\nAbstract: A combination of linear and nonlinear methods for feature fusion is introduced and the performance of this methodology is illustrated on a real-world problem: the detection of sudden and non-anticipated lapses of attention in car drivers due to drowsiness. To achieve this, signals coming from heterogeneous sources are processed, namely the brain electric activity, variation in the pupil size, and eye and eyelid movements. For all the signals considered, the features are extracted both in the spectral domain and in state space. Linear features are obtained by the modified periodogram, whereas the nonlinear features are based on the recently introduced method of delay vector variance (DVV). The decision process based on such fused features is achieved by support vector machines (SVM) and learning vector quantization (LVQ) neural networks. For the latter also methods of metrics adaptation in the input space are applied. The parameters of all utilized algorithms are optimized empirically in order to gain maximal classification accuracy. It is also shown that metrics adaptation by weighting the input features can improve the classification accuracy, but only to a limited extent. Limited improvements are also obtained when fusing features of selected signals, but highest improvements are gained by fusion of features of all available signals. In this case test errors are reduced down to 9% in the mean, which clearly illustrates the potential of our methodology to establish a reference standard of drowsiness and microsleep detection devices for future online driver monitoring.\",\n \"Title: Data Compression For Simultaneous/Sequential Inference Tasks In Sensor Networks\\nYear: 2006\\n\\nAbstract: Sensor networks typically perform multiple inference tasks and compression is often used to aid in the sharing of data. Compression degrades the inference accuracy and should be optimized for the tasks at hand. Unfortunately, simultaneous optimization for multiple tasks is not generally possible - typically a fundamental trade-off exists that has not been previously explored. A particularly relevant and interesting scenario occurs with a task-driven sequence of inferences. This paper develops a framework for data-optimized data compression for the case of multiple inferences. In particular, the Fisher information matrix (FIM) is used to derive a suitable scalar distortion measure for multiple estimation tasks, while the Chemoff distance is used for decision tasks. Theoretical results are presented that support the use of this particular scalar FIM-based distortion. The method is demonstrated with application to the sequential problem of first detecting a common intercepted signal among sensors and then once detected progressing to the location of the source.\",\n \"Title: Digital Imaging Sensor Identification (Further Study)\\nYear: 2007\\n\\nAbstract: In this paper, we revisit the problem of digital camera sensor identification using photo-response non-uniformity noise (PRNU). Considering the identification task as a joint estimation and detection problem, we use a simplified model for the sensor output and then derive a Maximum Likelihood estimator of the PRNU. The model is also used to design optimal test statistics for detection of PRNU in a specific image. To estimate unknown shaping factors and determine the distribution of the test statistics for the image-camera match, we construct a predictor of the test statistics on small image blocks. This enables us to obtain conservative estimates of false rejection rates for each image under Neyman-Pearson testing. We also point out a few pitfalls in camera identification using PRNU and ways to overcome them by preprocessing the estimated PRNU before identification.\",\n \"Title: Imaging sensor noise as digital X-ray for revealing forgeries\\nYear: 2007\\n\\nAbstract: In this paper, we describe a new forensic tool for revealing digitally altered images by detecting the presence of photo-response nonuniformity noise (PRNU) in small regions. This method assumes that either the camera that took the image is available to the analyst or at least some other nontampered images taken by the camera are available. Forgery detection using the PRNU involves two steps - estimation of the PRNU from non-tampered images and its detection in individual image regions. From a simplified model of the sensor output, we design optimal PRNU estimators and detectors. Binary hypothesis testing is used to determine which regions are forged. The method is tested on forged images coming from a variety of digital cameras and with different JPEG quality factors. The approximate probability of falsely identifying a forged region in a non-forged image is estimated by running the algorithm on a large number of non-forged images.\",\n \"Title: Merging Neuroimaging and Multimedia: Methods, Opportunities, and Challenges\\nYear: 2014\\n\\nAbstract: Neuroimaging and brain mapping can provide meaningful guidance to multimedia analyses. and advanced computational multimedia analysis can be used to better understand the functional mechanisms of the human brain. Essentially, brain imaging and brain mapping techniques can serve as a bridge that links the digital representation of multimedia and the perception and comprehension of its content. This paper summarizes methods that integrate brain imaging with multimedia analysis and discusses the opportunities and challenges in this interdisciplinary field. In general, quantitative modeling of brain responses during multimedia comprehension has advanced content-based multimedia studies such as image and video classification and tagging. Multimedia analysis has promoted functional brain mapping by using naturalistic multimedia as stimuli during neuroimaging. Challenges and opportunities in merging neuroimaging and multimedia include the quantification of the brain's responses, the quantification of multimedia, and the mapping between brain responses and computational multimedia features.\",\n \"Title: Energy efficiency of MIMO transmissions in wireless sensor networks with diversity and multiplexing gains\\nYear: 2005\\n\\nAbstract: The energy efficiency of MIMO transmissions in wireless sensor networks is analyzed considering the trade-off between diversity and multiplexing gains. Various MIMO are studied with noncooperative, half-cooperative or cooperative realizations. Energies consumed in transmission, processing circuitry and cooperation are obtained, which show that the optimal energy efficiency requires both the diversity and the multiplexing gains be exploited.\",\n \"Title: Hidden-Markov-Model-Based Segmentation Confidence Applied to Container Code Character Extraction\\nYear: 2011\\n\\nAbstract: Automatic container code recognition (ACCR) has become an indispensable aspect of current intelligent container management systems. In real applications, an ACCR module sometimes faces the problem of missing characters, i.e., not all the 11 container code characters (CCCs) appear in the input image. However, a few of the present methods can process container code images with missing characters. Therefore, a method is proposed to extract the CCCs for both the situation wherein all the 11 CCCs appear in an image and the situation wherein some CCCs are missing. In this method, hidden Markov model (HMM)-based segmentation confidence is proposed to describe the probability of the segmented characters belonging to the container code. Based on the segmentation confidence, the segmented characters are determined whether they belong to the container code or not, and if there are some characters missing, the positions of these characters can be estimated. Various container code images have been used to test the proposed method. The results of the tests show that the method is effective.\",\n \"Title: Data compression using SVD and Fisher information for radar emitter location\\nYear: 2010\\n\\nAbstract: This paper presents a method that achieves large compression ratios for radar pulse trains exploited in time-difference-of-arrival/frequency-difference-of-arrival (TDOA/FDOA) emitter location; this method exploits pulse-to-pulse redundancy to get a compression ratio much higher than possible by using standard methods. We show how to use (i) the singular value decomposition (SVD) to exploit redundancy between radar pulses, and (ii) a Fisher information-based distortion criterion to enable elimination of pulses that are negligible to the FDOA estimation task. To use the SVD it is necessary to first gate the pulses, place them in a matrix and then align the pulses to get a matrix that is close to rank one. Finally, we employ reasonable coding schemes for the information to be sent and assess the achievable compression level. With such SVD-based coding the compression ratio depends on the number of pulses intercepted and the number of samples taken per pulse; depending on the scenario the compression ratio can range from about 4 up to 100 or more. Fisher information-based removal of pulses is shown to improve the compression ratio beyond what is achievable using only the SVD approach while having negligible impact on the FDOA accuracy; it does, however, degrade the TDOA accuracy. However, we demonstrate that the SVD method includes an inherent de-noising effect (common in SVD-based signal processing) that provides an improvement in TDOA accuracy over the case of no compression processing; thus, the overall impact on TDOA/FDOA accuracy can be negligible while providing significant compression ratios for typical radar signals.\",\n \"Title: Top-K probabilistic closest pairs query in uncertain spatial databases\\nYear: 2011\\n\\nAbstract: An important topic in the field of spatial data management is processing the queries involving uncertain locations. This paper focuses on the problem of finding probabilistic K closest pairs between two uncertain spatial datasets, namely, Top-K probabilistic closest pairs (TopK-PCP) query, which has popular usages in real applications. Specifically, given two uncertain datasets in which each spatial object is modeled by a set of sample points, a TopK-PCP query retrieves the pairs with top K maximal probabilities of being the closest pair. Due to the inherent uncertainty of data objects, previous techniques to answer K-closest pairs (K-CP) queries cannot be directly applied to our TopK-PCP problem. Motivated by this, we propose a novel method to evaluate TopK-PCP query effectively. Extensive experiments are performed to demonstrate the effectiveness of our method.\",\n \"Title: An efficient method for cleaning dirty-events over uncertain data in WSNs\\nYear: 2011\\n\\nAbstract: Event detection in wireless sensor networks (WSNs) has attracted much attention due to its importance in many applications. The erroneous abnormal data generated during event detection are prone to lead to false detection results. Therefore, in order to improve the reliability of event detection, we propose a dirty-event cleaning method based on spatio-temporal correlations among sensor data. Unlike traditional fault-tolerant approaches, our method takes into account the inherent uncertainty of sensor measurements and focuses on the type of directional events. A probability-based mapping scheme is introduced, which maps uncertain sensor data into binary data. Moreover, we give formulated definitions of transient dirty-event (TDE) and permanent dirty-event (PDE), which are cleaned by a novel fuzzy method and a collaborative cleaning scheme, respectively. Extensive experimental results show the effectiveness of our dirty-event cleaning method.\",\n \"Title: Geometry-adaptive data compression for TDOA/FDOA location [wireless sensor network applications]\\nYear: 2005\\n\\nAbstract: The location of an emitting target is estimated by intercepting its emitted signal and sharing it among several sensors to measure the time-difference-of-arrival (TDOA) and the frequency-difference-of-arrival (FDOA). Doing this in a timely and energy efficient fashion, which is especially important for wireless sensor network applications, requires effective data compression. Since the commonly used MSE distortion measure is only weakly related to optimal TDOA/FDOA estimation, in this paper, we derive a new class of non-MSE distortion measures for TDOA/FDOA estimation using the concept of Fisher information. We then use these new distortion measures to compress the data using a wavelet packet transform and show that it improves TDOA/FDOA estimation accuracies relative to using the MSE-based compression. Finally, a scheme of applying our algorithms in a wireless sensor network is proposed, and energy efficiency and accuracy enhancement of the proposed scheme over that of a traditional scheme using MSE is shown through simulations.\",\n \"Title: Dimensionality reduction with generalized linear models\\nYear: 2013\\n\\nAbstract: In this paper, we propose a general dimensionality reduction method for data generated from a very broad family of distributions and nonlinear functions based on the generalized linear model, called Generalized Linear Principal Component Analysis (GLPCA). Data of different domains often have very different structures. These data can be modeled by different distributions and reconstruction functions. For example, real valued data can be modeled by the Gaussian distribution with a linear reconstruction function, whereas binary valued data may be more appropriately modeled by the Bernoulli distribution with a logit or probit function. Based on general linear models, we propose a unified framework for extracting features from data of different domains. A general optimization algorithm based on natural gradient ascent on distribution manifold is proposed for obtaining the maximum likelihood solutions. We also present some specific algorithms derived from this framework to deal with specific data modeling problems such as document modeling. Experimental results of these algorithms on several data sets are shown for the validation of GLPCA.\",\n \"Title: Clustering via random walk hitting time on directed graphs\\nYear: 2008\\n\\nAbstract: In this paper, we present a general data clustering algorithm which is based on the asymmetric pairwise measure of Markov random walk hitting time on directed graphs. Unlike traditional graph based clustering methods, we do not explicitly calculate the pairwise similarities between points. Instead, we form a transition matrix of Markov random walk on a directed graph directly from the data. Our algorithm constructs the probabilistic relations of dependence between local sample pairs by studying the local distributions of the data. Such dependence relations are asymmetric, which is a more general measure of pairwise relations than the similarity measures in traditional undirected graph based methods in that it considers both the local density and geometry of the data. The probabilistic relations of the data naturally result in a transition matrix of Markov random walk. Based on the random walk viewpoint, we compute the expected hitting time for all sample pairs, which explores the global information of the structure of the underlying directed graph. An asymmetric measure based clustering algorithm, called K-destinations, is proposed for partitioning the nodes of the directed graph into disjoint sets. By utilizing the local distribution information of the data and the global structure information of the directed graph, our method is able to conquer some limitations of traditional pairwise similarity based methods. Experimental results are provided to validate the effectiveness of the proposed approach.\",\n \"Title: QUALITY ASSESSMENT OF HYBRID NONLINEAR FILTERS\\nYear: 2004\\n\\nAbstract: Traditionally, researchonadaptivesignal processinghasbeen conducted with the aim of designing adaptive filters with high performance in terms of some prescribed performance measure. However, little is known about how such filters influence the nature of the processed signal. Based upon some recently introduced results on dealing with nonlinear- ity within a signal in hand, we provide a critical assessment of the qualitative performance of common linear and non- linear filters and their combinations. An insight into the performance of so called hybrid filters is provided, which is achieved for combinations of standard nonlinear (neural) and linear filters. It is shown that depending on the appli- cation, it is important not only to look for best filter perfor- mance in terms of some quantitative measure of the error but also for a filter that will not change the character of a signal. Simulation results support the analysis.\",\n \"Title: Online Detection Of The Modality Of Complex-Valued Real World Signals\\nYear: 2008\\n\\nAbstract: A novel method for the online detection of the modality of complex-valued nonlinear and nonstationary signals is introduced. This is achieved using a convex combination of complex nonlinear adaptive filters with different transient characteristics. To facilitate the online mode of operation, the convex mixing parameter. within the proposed architecture is made gradient adaptive. Our focus is on the most important aspect of complex nonlinear modeling, that is, the identification of the split-complex and fully-complex nature of the signal in hand. The algorithms derived are robust and capable of tracking the changes in the modality of both benchmark and real world radar and wind complex vector fields.\",\n \"Title: Study On Arc Characteristics Of A Dc Bridge-Type Contact In Air And Nitrogen At Different Pressure\\nYear: 2014\\n\\nAbstract: High voltage DC contactors, for operation at voltage levels up to at least about 300 volts, find their increasing markets in applications such as electrical vehicles and aircrafts in which size and weight of cables are of extreme importance. The copper bridge-type contact, cooperated with magnetic field provided by permanent magnets and sealed in an arc chamber filled with high pressure gases, is a mainly used structure to interrupt the DC arc rapidly. Arc characteristic in different gases at different pressure varies greatly. This paper is focused on the arc characteristics of the bridge-type contact system when magnetic field is applied with nitrogen and gas at different pressure. The pressure of the gases varies from 1 atm to 2.5 atm. Arc characteristics, such as arc durations at different stages and arc motions in those gases are comparatively studied. The results are instructive for choosing the suitable arcing atmosphere in a DC bridge-type arc chamber of a contactor.\",\n \"Title: A New Framework For Container Code Recognition By Using Segmentation-Based And Hmm-Based Approaches\\nYear: 2015\\n\\nAbstract: Traditional methods for automatic recognition of container code in visual images are based on segmentation and recognition of isolated characters. However, when the segment fails to separate each character from the others, those methods will not function properly. Sometimes the container code characters are printed or arranged very closely, which makes it a challenge to isolate each character. To address this issue, a new framework for automatic container code recognition (ACCR) in visual images is proposed in this paper. In this framework, code-character regions are first located by applying a horizontal high-pass filter and scan line analysis. Then, character blocks are extracted from the code-character regions and further classified into two categories, i.e. single-character block and multi-character block. Finally, a segmentation-based approach is implemented for recognition of the characters in single-character blocks, and a hidden Markov model (HMM)-based method is proposed for the multi-character blocks. The experimental results demonstrate the effectiveness of the proposed method, which can successfully recognize the container code with closely arranged characters.\",\n \"Title: Safe Sequential Path Planning Of Multi-Vehicle Systems Via Double-Obstacle Hamilton-Jacobi-Isaacs Variational Inequality\\nYear: 2014\\n\\nAbstract: We consider the problem of planning trajectories for a group of N vehicles, each aiming to reach its own target set while avoiding danger zones of other vehicles. The analysis of problems like this is extremely important practically, especially given the growing interest in utilizing unmanned aircraft systems for civil purposes. The direct solution of this problem by solving a single-obstacle Hamilton-Jacobi-Isaacs (HJI) variational inequality (VI) is numerically intractable due to the exponential scaling of computation complexity with problem dimensionality. Furthermore, the single-obstacle HJI VI cannot directly handle situations in which vehicles do not have a common scheduled arrival time. Instead, we perform sequential path planning by considering vehicles in order of priority, modeling higher-priority vehicles as time-varying obstacles for lower-priority vehicles. To do this, we solve a double-obstacle HJI VI which allows us to obtain the reach-avoid set, defined as the set of states from which a vehicle can reach its target while staying within a time-varying state constraint set. From the solution of the double-obstacle HJI VI, we can also extract the latest start time and the optimal control for each vehicle. This is a first application of the double-obstacle HJI VI which can handle systems with time-varying dynamics, target sets, and state constraint sets, and results in computation complexity that scales linearly, as opposed to exponentially, with the number of vehicles in consideration.\",\n \"Title: A Memristive Diode Bridge-Based Canonical Chua's Circuit.\\nYear: 2014\\n\\nAbstract: A novel memristor circuit is presented, which is generated from the canonical Chua's circuit by replacing the Chua's diode with a first order memristive diode bridge. The circuit dynamical characteristics with the variations of circuit parameters are investigated both theoretically and numerically. It can be found that the circuit has three determined equilibrium points, including a zero saddle point and two nonzero saddle-foci with index 2. Specially, the circuit is non-dissipative in the neighborhood of the zero saddle point, and there exists complex nonlinear phenomena of coexisting bifurcation modes and coexisting chaotic attractors. Experimental observations are performed to verify the numerical simulation results.\",\n \"Title: Study of the product color's image based on the event-related potentials.\\nYear: 2014\\n\\nAbstract: This research presents a new approach to explore the relationship between perception of product's color and their image. Event-related potentials (ERP) are used to reveal the brain responds to variation of image words within the same color category. Sofa was used as an example in this study. Firstly, all of the sample sofa pictures were made in the warm color tone according to the HSB color space; Next, through a questionnaire survey, we deduced that the three adjective words to match the color in three degree are: (i) passionate, (ii) mild, (iii) refreshing. The evaluation result showed that the reaction time were shorter for Related (passionate) and Conflict words (mild) than for the Vague word (refreshing). P200 and N400 components were identified in the -100 to 600 ms interval by the repeated analysis. The P200 component was larger for the related condition than for the unrelated condition, in addition, a right anterior P200 effect was observed. Meanwhile, the N400 component can be elicited by both Vague word and Conflict word, which suggested that these two kinds of word were not match the image of the target color. These findings reveal that the ERP can identify the relationship between semantic and perception of color sensitively, therefore, can help designers in achieving a desirable image of product's color effectively.\",\n \"Title: Multiplayer reach-avoid games via low dimensional solutions and maximum matching\\nYear: 2014\\n\\nAbstract: We consider a multiplayer reach-avoid game with an equal number of attackers and defenders moving with simple dynamics on a two-dimensional domain possibly with obstacles. The attacking team attempts to send as many attackers to a certain target location as possible quickly while the defenders aim to capture the attackers to prevent the attacking team from reaching its goal. The analysis of problems like this plays an important role in collision avoidance, motion planning, and aircraft control, among other applications. Computing optimal solutions for such multiplayer games is intractable due to numerical intractibility. This paper provides a first attempt to address such computational intractability by combining maximum matching in graph theory with the classical Hamilton-Jacobi-Isaacs approach. In addition, our solution provides an initial step to take cooperation into account by computing maximum matching in real time.\",\n \"Title: Design of a neural decoder by sensory prediction and error correction\\nYear: 2014\\n\\nAbstract: Brain-machine interfaces (BMI) hold great potential to improve the quality of life of many patients with disabilities. The neural decoder, which expresses the mapping between the neural signals and the subject's motion, plays an important role in BMI systems. Conventional neural decoders are generally in the form of a kinematic Kalman filter which does not possess an explicit mechanism to deal with the unavoidable mismatch between the biological system and the model of the system used by the decoder. This paper presents a novel design of a neural decoder that uses a one-step model predictive controller to generate a control signal that compensates for the inherent model mismatch. The effectiveness of the proposed decoding algorithm compares favorably to the state-of-the-art Kalman filter in numerical simulations with different degrees of model mismatch.\",\n \"Title: A path defense approach to the multiplayer reach-avoid game\\nYear: 2014\\n\\nAbstract: We consider a multiplayer reach-avoid game played between N attackers and N defenders moving with simple dynamics on a general two-dimensional domain. The attackers attempt to win the game by sending at least M of them (1 ≤ M ≤ N) to a target location while the defenders try to prevent the attackers from doing so by capturing them. The analysis of this game plays an important role in collision avoidance, motion planning, and aircraft control, among other applications involving cooperative agents. The high dimensionality of the game makes computing an optimal solution for either side intractable when N > 1. The solution is difficult even when N = 1. To address this issue, we present an efficient, approximate solution to the 1 vs. 1 problem. We call the approximate solution the “path defense solution”, which is conservative towards the defenders. This serves as a building block for an approximate solution of the multiplayer game. Compared to the classical Hamilton-Jacobi-Isaacs approach for solving the 1 vs. 1 game, our new method is orders of magnitude faster, and scales much better with the number of players.\",\n \"Title: The Study Of Data Governance For Telecom Network Management\\nYear: 2014\\n\\nAbstract: Data is an important asset of telecom operators, and data governance is an important method for telecom operators to manage data. This paper studies the characteristics of BSS and OSS data telecom operators, and proposes the architecture of data fusion platform and data hierarchical model. The basic method of BSS and OSS data fusion is then presented, and the wide table technology is adopted to organize and unify data model layer in order to realize the construction of the confusion application supporting cross-domain data fusion.\",\n \"Title: Qoe-Oriented Resource Allocation For Femtocell Networks\\nYear: 2014\\n\\nAbstract: This paper studies the resource allocation in a femtocell network, which aims to maximize the user-perceived Quality of Experience (QoE). By introducing a QoE-based assessment model, the problem is formulated as a combinational optimization problem, which is non-concave and difficult to develop a final solution. A heuristic PRB (Physical Resource Block) allocation algorithm and an adaptive power allocation algorithm are proposed for the final solution, in which a priority mechanism is employed for the network to give a higher priority on its resources to subscribers than the public users. Simulation results show that the proposed algorithms can improve the overall perceived quality from the user's perspective in compassion with the traditional Quality of Service (QoS) oriented algorithm.\",\n \"Title: Defending Against Fingerprint-Copy Attack in Sensor-Based Camera Identification\\nYear: 2011\\n\\nAbstract: Sensor photoresponse nonuniformity has been proposed as a unique identifier (fingerprint) for various forensic tasks, including digital-camera ballistics in which an image is matched to the specific camera that took it. The problem investigated here concerns the situation when an adversary estimates the sensor fingerprint from a set of images and superimposes it onto an image from a different camera to frame an innocent victim. This paper proposes a reliable method for detecting such fake fingerprints under rather mild and general assumptions about the adversary's activity and the means available to the victim. The proposed method is subjected to experiments to evaluate its reliability as well as its limitations. The conclusion that can be made from this study is that planting a sensor fingerprint in an image without leaving a trace is significantly more difficult than previously thought.\",\n \"Title: A Built-in Single Event Upsets Detector for Sequential Cells\\nYear: 2016\\n\\nAbstract: Abstract A built-in single event upsets (SEUs) detector is presented in this paper. This detector utilizes charge sharing to detect an SEU in a sequential cell, and the detection process is analyzed through Accuro simulations in a 65 nm technology. The normal operation of this detector would not induce obvious performance degradation of the target circuit. Through using this detector, error correction can be achieved based on dual modular redundancy (DMR) while the related power is about 20.4 % lower than that induced by triple modular redundancy (TMR).\",\n \"Title: Self-Excited And Hidden Attractors Found Simultaneously In A Modified Chua'S Circuit\\nYear: 2015\\n\\nAbstract: By replacing the Chua's diode in Chua's circuit with a first-order hybrid diode circuit, a fourth-order modified Chua's circuit is presented. The circuit has an unstable zero saddle point and two nonzero saddle-foci. By Routh-Hurwitz criterion, it is found that in a narrow parameter region, the two nonzero saddle-foci have a transition from unstable to stable saddle-foci, leading to generations of self-excited and hidden attractors in the modified Chua's circuit simultaneously, which have not been previously reported. Complex dynamical behaviors are investigated both numerically and experimentally. The results indicate that the proposed circuit exhibits complicated nonlinear phenomena including self-excited attractors, coexisting self-excited attractors, hidden attractors, and coexisting hidden attractors.\",\n \"Title: Comparisons On Arc Behavior And Contact Performance Between Cu And Cu-Mo Alloys In A Bridge-Type Contact System\\nYear: 2015\\n\\nAbstract: Cu-Mo alloy carries forward not only high electrical conductivity and high thermal conductivity from Cu but also high hardness from Mo, which makes it a promising potential application in electrical contact fields. In this paper, arc characteristic and erosion characteristic of Cu-Mo contacts are studied with a bridge-type contact high speed break mechanism on DC270 V/200 A load condition. And in each experiment group, 2500 times break operations are carried out. During every break operation, a high-speed AD card is used to record voltage and current signal of the arc, a high-speed camera is applied to record arcing process, and the temperature of contacts and arc are acquired by thermocouple and spectrometer, respectively. The mass and contact resistance of contacts are measured before and after every group experiment. Besides, the photograph of contact surface is taken by SEM to help analyze the erosion characteristic. The comparison between Cu-Mo contacts and Cu contacts indicates that although Cu contacts have a better electrical conductivity and thermal conductivity, Cu-Mo contacts can decrease the temperature of arc to prevent thermal breakdown, and they are also harder to be ablated and have a longer life span.\",\n \"Title: Guaranteeing Safety and Liveness of Unmanned Aerial Vehicle Platoons on Air Highways.\\nYear: 2016\\n\\nAbstract: Recently, there has been immense interest in using unmanned aerial vehicles (UAVs) for civilian operations such as package delivery, aerial surveillance, and disaster response. As a result, UAV traffic management systems are needed to support potentially thousands of UAVs flying simultaneously in the air space, in order to ensure their liveness and safety requirements are met. Currently, the analysis of large multi-agent systems cannot tractably provide these guarantees if the agentsu0027 set of maneuvers are unrestricted. In this paper, we propose to have platoons of UAVs flying on air highways in order to impose the air space structure that allows for tractable analysis and intuitive monitoring. For the air highway placement problem, we use the flexible and efficient fast marching method to solve the Eikonal equation, which produces a sequence of air highways that minimizes the cost of flying from an origin to any destination. Within the platoons that travel on the air highways, we model each vehicle as a hybrid system with modes corresponding to its role in the platoon. Using Hamilton-Jacobi reachability, we propose several liveness controllers and a safety controller that guarantee the success and safety of all mode transitions. For a single altitude range, our approach guarantees safety for one safety breach per vehicle; in the unlikely event of multiple safety breaches, safety can be guaranteed over multiple altitude ranges. We demonstrate the satisfaction of liveness and safety requirements through simulations of three common scenarios.\",\n \"Title: Multi-Vehicle Collision Avoidance Via Hamilton-Jacobi Reachability And Mixed Integer Programming\\nYear: 2016\\n\\nAbstract: Multi-agent differential games are important and useful tools for analyzing many practical problems. With the recent surge of interest in using UAVs for civil purposes, the importance and urgency of developing tractable multi-agent analysis techniques that provide safety and performance guarantees is at an all-time high. Hamilton-Jacobi (HJ) reachability has successfully provided safety guarantees to small-scale systems and is flexible in terms of system dynamics. However, the exponential complexity scaling of HJ reachability prevents its direct application to large scale problems when the number of vehicles is greater than two. In this paper, we overcome the scalability limitations of HJ reachability by using a mixed integer program that exploits the properties of HJ solutions to provide higher-level control logic. Our proposed method provides safety guarantee for three-vehicle systems - a previously intractable task for HJ reachability - without incurring significant additional computation cost. Furthermore, our method is scalable beyond three vehicles and performs significantly better by several metrics than an extension of pairwise collision avoidance to multi-vehicle collision avoidance. We demonstrate our proposed method in simulations.\",\n \"Title: Safe Sequential Path Planning of Multi-Vehicle Systems Under Presence of Disturbances and Imperfect Information.\\nYear: 2016\\n\\nAbstract: Recently, there has been an immense surge of interest in using unmanned aerial vehicles (UAVs) for civil purposes. Multi-UAV systems are safety-critical, and safety guarantees must be made to ensure no undesirable configurations such as collisions occur. Hamilton-Jacobi (HJ) reachability is ideal for analyzing such safety-critical systems because it provides safety guarantees and is flexible in terms of system dynamics; however, its direct application is limited to small-scale systems of no more than two vehicles because of the exponential-scaling computation complexity. By assigning vehicle priorities, the sequential path planning (SPP) method allows multi-vehicle path planning to be done with a computation complexity that scales linearly with the number of vehicles. Previously the SPP method assumed no disturbances in the vehicle dynamics, and that every vehicle has perfect knowledge of the position of higher-priority vehicles. In this paper, we make SPP more practical by providing three different methods for accounting for disturbances in dynamics and imperfect knowledge of higher-priority vehicles. Each method has advantages and disadvantages with different assumptions about information sharing. We demonstrate our proposed methods in simulations.\",\n \"Title: Accelerating submovement decomposition with search space reduction heuristics\\nYear: 2015\\n\\nAbstract: Movements made by healthy individuals can be characterized as superpositions of smooth bell-shaped velocity curves. Decomposing complex movements into these simpler “submovement” building blocks is useful for studying the neural control of movement as well as measuring motor impairment due to neurological injury. Approach: One prevalent strategy to submovement decomposition is to formulate it as an optimization problem. This optimization problem is non-convex and finding an exact solution is computationally burdensome. We build on previous literature which generated approximate solutions to the submovement optimization problem. Results: First, we demonstrate broad conditions on the submovement building block functions that enable the optimization variables to be partitioned into disjoint subsets, allowing for a faster alternating minimization solution. Specifically, the amplitude parameters of a submovement can typically be fit independently of its shape parameters. Second, we develop a method to concentrate the search in regions of high error to make more efficient use of optimization routine iterations. Conclusion: Both innovations result in substantial reductions in computation time across multiple non-human primate subjects and diverse task conditions. Significance: These innovations may accelerate analysis of submovements for basic neuroscience and enable realtime applications of submovement decomposition.\",\n \"Title: Application of STBC-encoded cooperative transmissions in wireless sensor networks\\nYear: 2005\\n\\nAbstract: The efficiency of space-time block code-encoded (STBC) cooperative transmission is studied within low-energy adaptive clustering hierarchy (LEACH), which is a typical networking/communication protocol for wireless sensor networks. Cooperation protocol with low overhead is proposed, and synchronization requirements among cooperating sensors are discussed. Energy efficiency is analyzed as a tradeoff...\",\n \"Title: Identifying valence and arousal levels via connectivity between EEG channels\\nYear: 2015\\n\\nAbstract: Implicit emotion tagging is a central theme in the area of affective computing. To this end, Several physiological signals acquired from subjects can be employed, for example, electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) from brain, electrocardiography (ECG) from cardiac activities, and other peripheral physiological signals, such as galvanic skin resistance, electromyogram (EMG), blood volume pressure etc. Brain is regarded as the place where emotional activities evoke. Determining affective states by observing brain activities directly is of therefore great interest. There are several published works that use EEG signals to identify affective states in different aspects with various stimuli, e.s., images, musics and videos. In this paper, we propose to adopt EEG connectivity between electrodes to identify subjects' affective levels in both valence and arousal space during video stimuli presentation. Three catagories of connectivity are adopted in magnitude and phase domains. One open accessed affective database, DEAP, is used as benchmark. We will show that with the proposed connectivity-based representation, the accuracy of affective levels identification tasks are higher than the same tasks in existing works based on same database.\",\n \"Title: Reach-avoid problems with time-varying dynamics, targets and constraints\\nYear: 2015\\n\\nAbstract: We consider a reach-avoid differential game, in which one of the players aims to steer the system into a target set without violating a set of state constraints, while the other player tries to prevent the first from succeeding; the system dynamics, target set, and state constraints may all be time-varying. The analysis of this problem plays an important role in collision avoidance, motion planning and aircraft control, among other applications. Previous methods for computing the guaranteed winning initial conditions and strategies for each player have either required augmenting the state vector to include time, or have been limited to problems with either no state constraints or entirely static targets, constraints and dynamics. To incorporate time-varying dynamics, targets and constraints without the need for state augmentation, we propose a modified Hamilton-Jacobi-Isaacs equation in the form of a double-obstacle variational inequality, and prove that the zero sublevel set of its viscosity solution characterizes the capture basin for the target under the state constraints. Through this formulation, our method can compute the capture basin and winning strategies for time-varying games at virtually no additional computational cost relative to the time-invariant case. We provide an implementation of this method based on well-known numerical schemes and show its convergence through a simple example; we include a second example in which our method substantially outperforms the state augmentation approach.\",\n \"Title: An SEU-Resilient SRAM Bitcell in 65-nm CMOS Technology.\\nYear: 2016\\n\\nAbstract: This paper presents an SEU-resilient 12 T SRAM bitcell. Simulation results demonstrate that it has higher critical charge than the traditional 6 T cell. Alpha and proton testing results validate that it has a lower soft error rate compared to the reference designs for all data patterns and supply voltage levels. The improvement in SEU tolerance is achieved at the expense of 2X area penalty.\",\n \"Title: Novel Hotspot Information Analysis System Using Automatic Information Extraction.\\nYear: 2016\\n\\nAbstract: There is large amount of information available on the Internet, which introduces difficulties in capturing and analyzing hotspot information. In this paper, we propose a novel hotspot information analysis system with automatic information extraction using the technologies of internet crawling, similarity elimination and abstract generation. System verification results show that, compared to the traditional solutions based on manual extraction and analysis, the proposed method are more capable of realizing the automated information extraction and analysis, thus improve the efficiency of hotspot analysis.\",\n \"Title: Instruction-Vulnerability-Factor-Based Reliability Analysis Model for Program Memory.\\nYear: 2016\\n\\nAbstract: Bit faults induced by single-event upsets in instruction may not cause a system to experience an error. The instruction vulnerability factor (IVF) is first defined to quantify the effect of non-effective upsets on program reliability in this paper; and the mean time to failure (MTTF) model of program memory is then derived based on IVF. Further analysis of MTTF model concludes that the MTTF of program memory using error correcting code (ECC) and scrubbing is not always better than unhardened program memory. The constraints that should be met upon utilizing ECC and scrubbing in program memory are presented for the first time, to the best of authors' knowledge. Additionally, the proposed models and conclusions are validated by Monte Carlo simulations in MATLAB. These results show that the proposed models have a good accuracy and their margin of error is less than 3 % compared with MATLAB simulation results. It should be highlighted that our conclusions may be used to contribute to selecting the optimal fault-tolerant technique to harden the program memory.\",\n \"Title: Using Neural Networks for Fast Reachable Set Computations.\\nYear: 2016\\n\\nAbstract: Hamilton-Jacobi (HJ) reachability is a powerful tool that provides performance and safety guarantees for dynamical systems. Unfortunately, using the state-of-the-art dynamic programming-based approaches, HJ reachability is intractable for systems with more than five dimensions because its computational complexity scales exponentially with system dimension. To sidestep the curse of dimensionality, we propose an algorithm that leverages a neural network to approximate the minimum time-to-reach function to synthesize controls. We show that our neural network generates near optimal controls which are guaranteed to successfully drive the system to a target state. Our framework is not dependent on state space discretization, leading to a significant reduction in computation time and space complexity in comparison with dynamic programming-based approaches. Using this grid-free approach also enables us to plan over longer time horizons with relatively little additional computation overhead. Unlike many previous neural network reachability formulations, our approximation is conservative and hence any trajectories we generate will be strictly feasible. For demonstration, we specialize our new general framework to the Dubins car model and discuss how the general framework can be applied to other models with higher-dimensional state spaces.\",\n \"Title: Robust Sequential Path Planning Under Disturbances and Adversarial Intruder.\\nYear: 2016\\n\\nAbstract: Provably safe and scalable multivehicle trajectory planning is an important and urgent problem. Although this problem has been studied in the past, there has not been a method that guarantees both goal satisfaction and safety for vehicles with general nonlinear dynamics, while taking into account disturbances and potential adversarial agents, to the best of our knowledge. Hamilton-Jacobi (HJ) reachability is the ideal tool for guaranteeing goal satisfaction and safety under such scenarios, which has been successfully applied to many small-scale problems; however, its direct application in most cases becomes intractable when there are more than two vehicles due to the exponentially scaling computational complexity with respect to system dimension. In this paper, we take advantage of the guarantees provided by HJ reachability and eliminate the computation burden by assigning a strict priority ordering to vehicles under consideration. Under this sequential trajectory planning (STP) scheme, vehicles reserve portions in the airspace. The space-time portions guarantee dynamic feasibility, collision avoidance, and optimality of trajectories given the priority ordering. With a computation complexity that scales quadratically when accounting for both disturbances and an intruder, and linearly when accounting for only disturbances, the STP can tractably solve the multivehicle trajectory planning problem for vehicles with general nonlinear dynamics in a practical setting. We demonstrate our theory in representative simulations.\",\n \"Title: Fast Reachable Set Approximations Via State Decoupling Disturbances\\nYear: 2016\\n\\nAbstract: With the recent surge of interest in using robotics and automation for civil purposes, providing safety and performance guarantees has become extremely important. In the past, differential games have been successfully used for the analysis of safety-critical systems. In particular, the Hamilton-Jacobi (HJ) formulation of differential games provides a flexible way to compute the reachable set, which can characterize the set of states which lead to either desirable or undesirable configurations, depending on the application. While HJ reachability is applicable to many small practical systems, the curse of dimensionality prevents the direct application of HJ reachability to many larger systems. To address computation complexity issues, various efficient computation methods in the literature have been developed for approximating or exactly computing the solution to HJ partial differential equations, but only when the system dynamics are of specific forms. In this paper, we propose a flexible method to trade off optimality with computation complexity in HJ reachability analysis. To achieve this, we propose to simplify system dynamics by treating state variables as disturbances. We prove that the resulting approximation is conservative in the desired direction, and demonstrate our method using a four-dimensional plane model.\",\n \"Title: An implicit feedback integrated LDA-based topic model for IPTV program recommendation\\nYear: 2016\\n\\nAbstract: Internet protocol television (IPTV), the television services through the Internet, has become more and more popular in recent years. Many recommendation systems have been made for delivering personalized IPTV services, of which understanding users' preference is the most critical. The traditional recommendation system only considers the users' playing behavior, but other implicit feedback behaviors of users, such as browsing, collecting also reflect the users' preference. We propose a novel latent Dirichlet allocation (LDA)-based model, which considers users' playing behavior as well as the implicit feedback of browsing and collecting, to capture the inherent viewing preference of individual users. The implicit feedback integrated LDA model employs three LDA models (the playing, browsing, and collecting behavior topic model), which are integrated via TV program characteristic. Based on this, we further calculate the ratio of each behavior to the recommended results by logistic regression algorithm. The experimental results show that the proposed topic model yields an average 32.5% precision for recommending 10 videos and 200 topics in IPTV recommendation, and its performance is an average of 19.5% higher than that of LDA using playing behavior only.\",\n \"Title: Multiplayer Reach-Avoid Games via Pairwise Outcomes.\\nYear: 2017\\n\\nAbstract: A multiplayer reach-avoid game is a differential game between an attacking team with N A attackers and a defending team with N D defenders playing on a compact domain with obstacles. The attacking team aims to send M of the N A attackers to some target location, while the defending team aims to prevent that by capturing attackers or indefinitely delaying attackers from reaching the target. Although the analysis of this game plays an important role in many applications, the optimal solution to this game is computationally intractable when N A > 1 or N D > 1. In this technical note, we present two approaches for the N A = N D = 1 case to determine pairwise outcomes, and a graph theoretic maximum matching approach to merge these pairwise outcomes for an N A , N D > 1 solution that provides guarantees on the performance of the defending team. We will show that the four-dimensional Hamilton-Jacobi-Isaacs approach allows for real-time updates to the maximum matching, and that the two-dimensional path defense approach is considerably more scalable with the number of players while maintaining defender performance guarantees.\",\n \"Title: Provably Safe and Robust Drone Routing via Sequential Path Planning: A Case Study in San Francisco and the Bay Area.\\nYear: 2017\\n\\nAbstract: Provably safe and scalable multi-vehicle path planning is an important and urgent problem due to the expected increase of automation in civilian airspace in the near future. Hamilton-Jacobi (HJ) reachability is an ideal tool for analyzing such safety-critical systems and has been successfully applied to several small-scale problems. However, a direct application of HJ reachability to large scale systems is often intractable because of its exponentially-scaling computation complexity with respect to system dimension, also known as the \\\"curse of dimensionality\\\". To overcome this problem, the sequential path planning (SPP) method, which assigns strict priorities to vehicles, was previously proposed; SPP allows multi-vehicle path planning to be done with a linearly-scaling computation complexity. In this work, we demonstrate the potential of SPP algorithm for large-scale systems. In particular, we simulate large-scale multi-vehicle systems in two different urban environments, a city environment and a multi-city environment, and use the SPP algorithm for trajectory planning. SPP is able to efficiently design collision-free trajectories in both environments despite the presence of disturbances in vehicles' dynamics. To ensure a safe transition of vehicles to their destinations, our method automatically allocates space-time reservations to vehicles while accounting for the magnitude of disturbances such as wind in a provably safe way. Our simulation results show an intuitive multi-lane structure in airspace, where the number of lanes and the distance between the lanes depend on the size of disturbances and other problem parameters.\",\n \"Title: Exact and efficient Hamilton-Jacobi guaranteed safety analysis via system decomposition\\nYear: 2017\\n\\nAbstract: Hamilton-Jacobi (HJ) reachability is a method that provides rigorous analyses of the safety properties of dynamical systems. These guarantees can be provided by the computation of a backward reachable set (BRS), which represents the set of states from which the system may be driven into violating safety properties despite the system's best effort to remain safe. Unfortunately, the complexity of the BRS computation scales exponentially with the number of state dimensions. Although numerous approximation techniques are able to tractably provide conservative estimates of the BRS, they often require restrictive assumptions about system dynamics without providing an exact solution. In this paper we propose a general method for decomposing dynamical systems. Even when the resulting subsystems are coupled, relatively high-dimensional BRSs that were previously intractable or expensive to compute can now be quickly and exactly computed in lower-dimensional subspaces. As a result, the curse of dimensionality is alleviated to a large degree without sacrificing optimality. We demonstrate our theoretical results through a 3D Dubins Car model and a 6D Acrobatic Quadrotor model.\",\n \"Title: Safe Sequential Path Planning Under Disturbances And Imperfect Information\\nYear: 2017\\n\\nAbstract: Multi-UAV systems are safety-critical, and guarantees must be made to ensure no unsafe configurations occur. Hamilton-Jacobi (HJ) reachability is ideal for analyzing such safety-critical systems; however, its direct application is limited to small-scale systems of no more than two vehicles due to an exponentially-scaling computational complexity. Previously, the sequential path planning (SPP) method, which assigns strict priorities to vehicles, was proposed; SPP allows multi-vehicle path planning to be done with a linearly-scaling computational complexity. However, the previous formulation assumed that there are no disturbances, and that every vehicle has perfect knowledge of higher-priority vehicles' positions. In this paper, we make SPP more practical by providing three different methods to account for disturbances in dynamics and imperfect knowledge of higher-priority vehicles' states. Each method has different assumptions about information sharing. We demonstrate our proposed methods in simulations.\",\n \"Title: A Study for Human-Machine Interface Design of Spacecraft Display & Control Device Based on Eye-Tracking Experiments.\\nYear: 2017\\n\\nAbstract: The display & control device is the hub of human-machine interaction in the whole spacecraft's human-machine environment system. The rationality of its design affects the level of integration between human and machine directly. Therefore, the optimization design studies of manned spacecraft cabin's display & control device plays an important role on the development of spaceflight. The paper researches the design methods of manned spacecraft cabin's display & control device from the perspective of human-machine ergonomics. The specific steps of research are: Firstly, we will refine the design principles of human-machine interface by constructing the user behavior model; Secondly, we will work out the design and layout solutions of spacecraft cabin's display & control device based on the information from user behavior model; Finally, an eye-tracking experiment will be proposed to verify and optimize the solutions.\",\n \"Title: JPEG-Phase-Aware Convolutional Neural Network for Steganalysis of JPEG Images\\nYear: 2017\\n\\nAbstract: Detection of modern JPEG steganographic algorithms has traditionally relied on features aware of the JPEG phase. In this paper, we port JPEG-phase awareness into the architecture of a convolutional neural network to boost the detection accuracy of such detectors. Another innovative concept introduced into the detector is the \\\\\\\"catalyst kernel\\\\\\\" that, together with traditional high-pass filters used to pre-process images allows the network to learn kernels more relevant for detection of stego signal introduced by JPEG steganography. Experiments with J-UNIWARD and UED-JC embedding algorithms are used to demonstrate the merit of the proposed design.\",\n \"Title: BPPT — Bulk potential protection technique for hardened sequentials\\nYear: 2017\\n\\nAbstract: In this paper, we present a method for hardening memory and sequential cells against soft errors. The effect of the ionizing particle on the bulk potential is exploited to prevent the induced SET from propagating in the circuit. The proposed method requires a minimum number of extra transistors. The solution is applied to D Flip-Flop design, and alpha and heavy-ions test results are presented.\",\n \"Title: Coexisting Behaviors of Asymmetric Attractors in Hyperbolic-Type Memristor based Hopfield Neural Network.\\nYear: 2017\\n\\nAbstract: A new hyperbolic-type memristor emulator is presented and its frequency-dependent pinched hysteresis loops are analyzed by numerical simulations and confirmed by hardware experiments. Based on the emulator, a novel hyperbolic-type memristor based 3-neuron Hopfield neural network (HNN) is proposed, which is achieved through substituting one coupling-connection weight with a memristive synaptic weight. It is numerically shown that the memristive HNN has a dynamical transition from chaotic, to periodic, and further to stable point behaviors with the variations of the memristor inner parameter, implying the stabilization effect of the hyperbolic-type memristor on the chaotic HNN. Of particular interest, it should be highly stressed that for different memristor inner parameters, different coexisting behaviors of asymmetric attractors are emerged under different initial conditions, leading to the existence of multistable oscillation states in the memristive HNN. Furthermore, by using commercial discrete components, a nonlinear circuit is designed and PSPICE circuit simulations and hardware experiments are performed. The results simulated and captured from the realization circuit are consistent with numerical simulations, which well verify the facticity of coexisting asymmetric attractors' behaviors.\",\n \"Title: Hamilton-Jacobi Reachability: A Brief Overview And Recent Advances\\nYear: 2017\\n\\nAbstract: Hamilton-Jacobi (HJ) reachability analysis is an important formal verification method for guaranteeing performance and safety properties of dynamical systems; it has been applied to many small-scale systems in the past decade. Its advantages include compatibility with general nonlinear system dynamics, formal treatment of bounded disturbances, and the availability of well-developed numerical tools. The main challenge is addressing its exponential computational complexity with respect to the number of state variables. In this tutorial, we present an overview of basic HJ reachability theory and provide instructions for using the most recent numerical tools, including an efficient GPU-parallelized implementation of a Level Set Toolbox for computing reachable sets. In addition, we review some of the current work in high-dimensional HJ reachability to show how the dimensionality challenge can be alleviated via various general theoretical and application-specific insights.\",\n \"Title: Safe and Resilient Multi-vehicle Trajectory Planning Under Adversarial Intruder.\\nYear: 2017\\n\\nAbstract: Provably safe and scalable multi-vehicle trajectory planning is an important and urgent problem. Hamilton-Jacobi (HJ) reachability is an ideal tool for analyzing such safety-critical systems and has been successfully applied to several small-scale problems. However, a direct application of HJ reachability to multi-vehicle trajectory planning is often intractable due to the curse of dimensionality. To overcome this problem, the sequential trajectory planning (STP) method, which assigns strict priorities to vehicles, was proposed, STP allows multi-vehicle trajectory planning to be done with a linearly-scaling computation complexity. However, if a vehicle not in the set of STP vehicles enters the system, or even worse, if this vehicle is an adversarial intruder, the previous formulation requires the entire system to perform replanning, an intractable task for large-scale systems. In this paper, we make STP more practical by providing a new algorithm where replanning is only needed only for a fixed number of vehicles, irrespective of the total number of STP vehicles. Moreover, this number is a design parameter, which can be chosen based on the computational resources available during run time. We demonstrate this algorithm in a representative simulation of an urban airspace environment.\",\n \"Title: A Hybrid Framework For Multi-Vehicle Collision Avoidance\\nYear: 2017\\n\\nAbstract: With the recent surge of interest in UAVs for civilian services, the importance of developing tractable multi-agent analysis techniques that provide safety and performance guarantees has drastically increased. Hamilton-Jacobi (HJ) reachability has successfully provided these guarantees to small-scale systems and is flexible in terms of system dynamics. However, the exponential complexity scaling of HJ reachability with respect to system dimension prevents its direct application to larger-scale problems where the number of vehicles is greater than two. In this paper, we propose a collision avoidance algorithm using a hybrid framework for N + 1 vehicles through higher-level control logic given any N-vehicle collision avoidance algorithm. Our algorithm conservatively approximates a guaranteed-safe region in the joint state space of the N + 1 vehicles and produces a safety-preserving controller. In addition, our algorithm does not incur significant additional computation cost. We demonstrate our method in simulation.\",\n \"Title: A Method Of Large - Scale Log Pattern Mining\\nYear: 2017\\n\\nAbstract: With the development of the telecommunication network, more and more devices are used in the network, which has been a burden for the network operation and maintenance. At the same time, network devices generate large amounts of log data every day, recording the activities of each device in detail. As a result, the log can reflect the performance of network state, and sometimes, we can predict the occurrence of network failure based on the log. However, since the log has such features: big volume, multi-source heterogeneous and difficult to understand, people have not reasonably used it to analyze and predict network failure. Therefore, we propose a method for structuring a large number of device logs in the short term, and use the data generated from a real communication device network to verify the effect. Besides, we compare our method with the traditional log parsers, such as regular expressions, LogSig, etc. to demonstrate the efficient processing performance and accurate pattern extraction analysis for massive network device logs.\",\n \"Title: Identifying affective levels on music video via completing the missing modality.\\nYear: 2018\\n\\nAbstract: Emotion tagging is one theme of interest in affective computing, which labels stimuli with human understandable semantic information. Previous works indicate that modality fusion could improve the performance of this kind of tasks. However, acquiring the subjects’ responses is costly and time consuming, leading to that the response modality is absent for large part of multimedia contents, which is required by modality fusion methods. To address this problem, in this paper a novel emotion tagging framework is proposed, which completes the missing response modalities based on the conception of brain encoding. In the framework, an encoding model is built based on the response modality from subjects’ responses and the stimulus modality from stimulus contents. Then the model is applied to those videos whose response modalities are absent to complete the missing response modalities. Modality fusion is finally conducted on stimulus modality and response modality and followed by the classification methods. To test the performance of the proposed framework, DEAP dataset is adopted as a benchmark. In the experiments, three kinds of features are employed as stimulus modalities. Response modality and fused modality are computed under the proposed framework. Affective level identification is conducted as emotion tagging task. The results demonstrate that the accuracies of the proposed framework outperforms the accuracies obtained by using only stimulus modality. The improvements are higher than 5% for all kinds of stimulus modalities in valence and arousal in terms of accuracy. Additionally, the improvement of performance introduces no extra physiological data acquisition, saving economical and timing costs.\",\n \"Title: Coexistence Of Multiple Attractors In An Active Diode Pair Based Chua'S Circuit\\nYear: 2018\\n\\nAbstract: This paper focuses on the coexistence of multiple attractors in an active diode pair based Chua's circuit with smooth nonlinearity. With dimensionless equations, dynamical properties, including boundness of system orbits and stability distributions of two nonzero equilibrium points, are investigated, and complex coexisting behaviors of multiple kinds of disconnected attractors of stable point attractors, limit cycles and chaotic attractors are numerically revealed. The results show that unlike the classical Chua's circuit, the proposed circuit has two stable nonzero node-foci for the specified circuit parameters, thereby resulting in the emergence of multistability phenomenon. Based on two general impedance converters, the active diode pair based Chua's circuit with an adjustable inductor and an adjustable capacitor is made in hardware, from which coexisting multiple attractors are conveniently captured.\",\n \"Title: A 10-Transistor 65 nm SRAM Cell Tolerant to Single-Event Upsets\\nYear: 2016\\n\\nAbstract: A novel SRAM cell tolerant to single-event upsets (SEUs) is presented in this paper. By adding four more transistors inside, the proposed circuit can obtain higher critical charge at each internal node compared to the conventional 6-transistor (6T) cell. Arrays of 2k-bit capacitance of these two designs were implemented in a 65 nm CMOS bulk technology for comparison purpose. Radiation experiments showed that, at the nominal 1.0 V supply voltage, the proposed cell achieves 47.1 % and 49.3 % reduction in alpha and proton soft error rates (SER) with an area overhead of 37 %.\",\n \"Title: CRF-LSTM Text Mining Method Unveiling the Pharmacological Mechanism of Off-target Side Effect of Anti-Multiple Myeloma Drugs.\\nYear: 2018\\n\\nAbstract: Off-target effects played a vital role in the pharmacological understanding of drug efficacy and this research aimed to use text mining strategy to curate molecular level information and unveil the mechanism of off-target effect caused by the usage of anti-multiple myeloma (MM) drugs. After training a hybrid CNN-CRF-LSTM neural network upon the training data from TAC 2017 benchmark database, we extracted all of the side effects of 16 anti-MM drugs from drug labels, and combined the results with existed database. Afterwards, gene targets of anti-MM drugs were obtained by using structure similarity, and their related phenotypes were retrieved from Human Phenotype Ontology. Furthermore, linked phenotypes to candidate genes and adverse reaction of known drugs formed a knowledge graph. Through regulation analysis upon intersected phenotypes of drugs and target genes, an off-target effect caused by SLC7A7 was found, which with high possibility unveiled the pharmacological mechanism of side effect after using combination of anti-MM drugs.\",\n \"Title: BaRC: Backward Reachability Curriculum for Robotic Reinforcement Learning\\nYear: 2018\\n\\nAbstract: Model-free Reinforcement Learning (RL) offers an attractive approach to learn control policies for high dimensional systems, but its relatively poor sample complexity often necessitates training in simulated environments. Even in simulation, goal-directed tasks whose natural reward function is sparse remain intractable for state-of-the-art model-free algorithms for continuous control. The bottleneck in these tasks is the prohibitive amount of exploration required to obtain a learning signal from the initial state of the system. In this work, we leverage physical priors in the form of an approximate system dynamics model to design a curriculum for a model-free policy optimization algorithm. Our Backward Reachability Curriculum (BaRC) begins policy training from states that require a small number of actions to accomplish the task, and expands the initial state distribution backwards in a dynamically-consistent manner once the policy optimization algorithm demonstrates sufficient performance. BaRC is general, in that it can accelerate training of any model-free RL algorithm on a broad class of goal-directed continuous control MDPs. Its curriculum strategy is physically intuitive, easy-to-tune, and allows incorporating physical priors to accelerate training without hindering the performance, flexibility, and applicability of the model-free RL algorithm. We evaluate our approach on two representative dynamic robotic learning problems and find substantial performance improvement relative to previous curriculum generation techniques and naive exploration strategies.\",\n \"Title: Memristor-Based Canonical Chua's Circuit: Extreme Multistability in Voltage-Current Domain and Its Controllability in Flux-Charge Domain.\\nYear: 2018\\n\\nAbstract: This paper investigates extreme multistability and its controllability for an ideal voltage-controlled memristor emulator-based canonical Chua's circuit. With the voltage-current model, the initial condition-dependent extreme multistability is explored through analyzing the stability distribution of line equilibrium point and then the coexisting infinitely many attractors are numerically uncovered in such a memristive circuit by the attraction basin and phase portraits. Furthermore, based on the accurate constitutive relation of the memristor emulator, a set of incremental flux-charge describing equations for the memristor-based canonical Chua's circuit are formulated and a dimensionality reduction model is thus established. As a result, the initial condition-dependent dynamics in the voltage-current domain is converted into the system parameter-associated dynamics in the flux-charge domain, which is confirmed by numerical simulations and circuit simulations. Therefore, a controllable strategy for extreme multistability can be expediently implemented, which is greatly significant for seeking chaos-based engineering applications of multistable memristive circuits.\",\n \"Title: Three-Dimensional Memristive Hindmarsh-Rose Neuron Model with Hidden Coexisting Asymmetric Behaviors.\\nYear: 2018\\n\\nAbstract: Since the electrical activities of neurons are closely related to complex electrophysiological environment in neuronal system, a novel three-dimensional memristive Hindmarsh-Rose (HR) neuron model is presented in this paper to describe complex dynamics of neuronal activities with electromagnetic induction. The proposed memristive HR neuron model has no equilibrium point but can show hidden dynamical behaviors of coexisting asymmetric attractors, which has not been reported in the previous references for the HR neuron model. Mathematical model based numerical simulations for hidden coexisting asymmetric attractors are performed by bifurcation analyses, phase portraits, attraction basins, and dynamical maps, which just demonstrate the occurrence of complex dynamical behaviors of electrical activities in neuron with electromagnetic induction. Additionally, circuit breadboard based experimental results well confirm the numerical simulations.\",\n \"Title: Reach-Avoid Problems Via Sum-Of-Squares Optimization And Dynamic Programming\\nYear: 2018\\n\\nAbstract: Reach-avoid problems involve driving a system to a set of desirable configurations while keeping it away from undesirable ones. Providing mathematical guarantees for such scenarios is challenging but have numerous potential practical applications. Due to the challenges, analysis of reach-avoid problems involves making trade-offs between generality of system dynamics, generality of problem setups, optimality of solutions, and computational complexity. In this paper, we combine sumof- squares optimization and dynamic programming to address the reach-avoid problem, and provide a conservative solution that maintains reaching and avoidance guarantees. Our method is applicable to polynomial system dynamics and to general problem setups, and is more computationally scalable than previous related methods. Through a numerical example involving two single integrators, we validate our proposed theory and compare our method to Hamilton-Jacobi reachability. Having validated our theory, we demonstrate the computational scalability of our method by computing the reach-avoid set of a system involving two kinematic cars.\",\n \"Title: Simulation Of Metal Droplet Sputtering And Molten Pool On Copper Contact Under Electric Arc\\nYear: 2018\\n\\nAbstract: The micro-mechanism of molten pool and metal droplet sputtering are significant to the material erosion caused by breaking or making arcs especially for high-power switching devices. In this paper, based on Navier-Stokes equations for incompressible viscous fluid and potential equation for electric field, a 2D axially symmetric simplified hydrodynamic model was built to describe the formation of the molten metal droplet sputtering and molten pool under arc spot near electrode region. The melting process was considered by the relationship between melting metal volumetric percentage and temperature, a free surface of liquid metal deformation was solved by coupling moving mesh and the automatic re-meshing. The simulated metal droplet sputtering and molten pool behaviors are presented by the temperature and velocity distribution sequences. The influence mechanism of pressure distribution and heat flux on the formation of molten pool and metal droplet sputtering has been analyzed according to the temperature distribution and sputtering angles. Based on the simulation results, we can distinguish two different models of the molten metal droplet sputtering process: edge ejection and center ejection. Moreover, a new explanation is proposed based on calculated results with arc spot pressure distribution in the form of both unimodal and bimodal. It shows that the arc spot pressure distribution plays an important role in the metal droplet ejected from molten pool, the angle of the molten jet drop can be decreased along with the increment of the arc spot pressure.\",\n \"Title: Decomposition of Reachable Sets and Tubes for a Class of Nonlinear Systems.\\nYear: 2018\\n\\nAbstract: Reachability analysis provides formal guarantees for performance and safety properties of nonlinear control systems. Here, one aims to compute the backward reachable set (BRS) or tube (BRT)-the set of states from which the system can be driven into a target set at a particular time or within a time interval, respectively. The computational complexity of current approaches scales poorly, making app...\",\n \"Title: Flux-Charge Analysis Of Initial State-Dependent Dynamical Behaviors Of A Memristor Emulator-Based Chua'S Circuit\\nYear: 2018\\n\\nAbstract: It is known that dynamical behaviors of memristive circuit are significantly affected by its initial states, which are difficult to be explicitly analyzed or controlled in voltage-current domain and have become great obstacles for its potential engineering applications. In this paper, the complex initial state-dependent dynamical behaviors of a physically realized memristive Chua's circuit are detailed and investigated using incremental flux-charge modeling method. This circuit is modeled in terms of incremental flux and charge, in which the original line equilibrium point is converted into some determined equilibrium points relying on the initial states of the dynamic elements. Moreover, the special initial state-dependent behaviors are transformed into system parameter-associated behaviors. Consequently, the detailed influences of each initial state, even the occurrence of hidden oscillations, can readily be theoretically interpreted. Finally, the initial state-dependent behaviors are physically captured and directed in the equivalent realization circuit of the incremental flux-charge model.\",\n \"Title: Deep Residual Network for Steganalysis of Digital Images\\nYear: 2019\\n\\nAbstract: Steganography detectors built as deep convolutional neural networks have firmly established themselves as superior to the previous detection paradigm – classifiers based on rich media models. Existing network architectures, however, still contain elements designed by hand, such as fixed or constrained convolutional kernels, heuristic initialization of kernels, the thresholded linear unit that mimics truncation in rich models, quantization of feature maps, and awareness of JPEG phase. In this work, we describe a deep residual architecture designed to minimize the use of heuristics and externally enforced elements that is universal in the sense that it provides state-of-the-art detection accuracy for both spatial-domain and JPEG steganography. The key part of the proposed architecture is a significantly expanded front part of the detector that “computes noise residuals” in which pooling has been disabled to prevent suppression of the stego signal. Extensive experiments show the superior performance of this network with a significant improvement, especially in the JPEG domain. Further performance boost is observed by supplying the selection channel as a second channel.\",\n \"Title: Plug And Play Distributed Model Predictive Control For Heavy Duty Vehicle Platooning And Interaction With Passenger Vehicles\\nYear: 2018\\n\\nAbstract: Heavy duty vehicle (HDV) platooning has been widely accepted as a solution to reduce fuel consumption and traffic congestion. However, the control strategy for HDV platoons interacting with other vehicles is not yet well established. This work presents a new framework for handling the requests of passenger vehicles (PV) plugging in or out of an HDV platoon. It consists of three main steps. First, the basic cruising control of the platoon is achieved by a distributed model predictive control (DMPC) scheme. Second, redesign of controllers ensures the stability of closed loop Plug and Play (P&P) operation. Finally, a transition phase to steady-states guarantees the feasibility of the newly synthesized controllers. Additionally for the plug-in case, we propose a novel approach of Formation Coordinator that determines the optimal location at which the redesigned controller has the best initial feasibility. The performance of the proposed control framework is illustrated on a multi-vehicle platooning system.\",\n \"Title: Reach-Avoid Games Via Mixed-Integer Second-Order Cone Programming\\nYear: 2018\\n\\nAbstract: Reach-avoid games are excellent proxies for studying many problems in robotics and related fields, with applications including multi-robot systems, human-robot interactions, and safety-critical systems. However, solving reach-avoid games is difficult due to the conflicting and asymmetric goals of agents, and trade-offs between optimality, computational complexity, and solution generality are commonly required. This paper seeks to find attacker strategies in reach-avoid games that reduce computational complexity while retaining solution quality by using a receding horizon strategy. To solve for the open-loop strategy fast enough to enable a receding horizon approach, the problem is formulated as a mixed-integer second-order cone program. This formulation leverages the use of sums-of-squares optimization to provide guarantees that the strategy is robust to all possible defender policies. The method is demonstrated through numerical and hardware experiments.\",\n \"Title: On Infusing Reachability-Based Safety Assurance Within Probabilistic Planning Frameworks For Human-Robot Vehicle Interactions\\nYear: 2018\\n\\nAbstract: Action anticipation, intent prediction, and proactive behavior are all desirable characteristics for autonomous driving policies in interactive scenarios. Paramount, however, is ensuring safety on the road-a key challenge in doing so is accounting for uncertainty in human driver actions without unduly impacting planner performance. This paper introduces a minimally-interventional safety controller operating within an autonomous vehicle control stack with the role of ensuring collision-free interaction with an externally controlled (e.g., human-driven) counterpart. We leverage reachability analysis to construct a realtime (100 Hz) controller that serves the dual role of (1) tracking an input trajectory from a higher-level planning algorithm using model predictive control, and (2) assuring safety through maintaining the availability of a collision-free escape maneuver as a persistent constraint regardless of whatever future actions the other car takes. A full-scale steer-by-wire platform is used to conduct traffic weaving experiments wherein the two cars, initially side-by-side, must swap lanes in a limited amount of time and distance, emulating cars merging onto/off of a highway. We demonstrate that, with our control stack, the autonomous vehicle is able to avoid collision even when the other car defies the planner's expectations and takes dangerous actions, either carelessly or with the intent to collide, and otherwise deviates minimally from the planned trajectory to the extent required to maintain safety.\",\n \"Title: Clear Sanctions, Vague Rewards - How China's Social Credit System Currently Defines \\\"Good\\\" and \\\"Bad\\\" Behavior.\\nYear: 2019\\n\\nAbstract: China's Social Credit System (SCS) or shehui xinyong tixi) is expected to become the first digitally-implemented nationwide scoring system with the purpose to rate the behavior of citizens, companies, and other entities. Thereby, in the SCS, \\\"good\\\" behavior can result in material rewards and reputational gain while \\\"bad\\\" behavior can lead to exclusion from material resources and reputational loss. Crucially, for the implementation of the SCS, society must be able to distinguish between behaviors that result in reward and those that lead to sanction. In this paper, we conduct the first transparency analysis of two central administrative information platforms of the SCS to understand how the SCS currently defines \\\"good\\\" and \\\"bad\\\" behavior. We analyze 194,829 behavioral records and 942 reports on citizens' behaviors published on the official Beijing SCS website and the national SCS platform \\\"Credit China\\\", respectively. By applying a mixed-method approach, we demonstrate that there is a considerable asymmetry between information provided by the so-called Redlist (information on \\\"good\\\" behavior) and the Blacklist (information on \\\"bad\\\" behavior). At the current stage of the SCS implementation, the majority of explanations on blacklisted behaviors includes a detailed description of the causal relation between inadequate behavior and its sanction. On the other hand, explanations on redlisted behavior, which comprise positive norms fostering value internalization and integration, are less transparent. Finally, this first SCS transparency analysis suggests that socio-technical systems applying a scoring mechanism\",\n \"Title: Unique continuation property for the Zakharov-Kuznetsov equation.\\nYear: 2019\\n\\nAbstract: In this paper, we consider the unique continuation property for the Zakharov–Kuznetsov equation posed in a bounded domain. For this purpose, we establish a boundary Carleman estimate for the linear Zakharov–Kuznetsov operator.\",\n \"Title: Online-Offline Consistency Exploration Based On The Alternating Direction Method Of Multipliers\\nYear: 2016\\n\\nAbstract: Nowadays, online social network has become one of the main tools which people communicate with each other every day. The online users' behavior is a large amount of high dimension data. However, is online and offline behavior the mapping relation? This paper explores whether there is consistency between online and offline behavior using the Alternating Direction Method of Multipliers (ADMM) algorithm. The ADMM is becoming more and more popular recently, due to it can solve the problem of large-scale and complex data sets. ADMM was designed to solve the convex optimization problem. It is an iterative method that minimizes the objective augmented Lagrangian function.\",\n \"Title: Model Of Network Topic Detection Based On Web Usage Behaviour Mode Analysis And Mining Technology\\nYear: 2017\\n\\nAbstract: This research has caught researchers' wide attention for detecting network topic exactly with the arrival of big data era characterized by semi-structured or unstructured text. This paper proposes a model of network topic detection based on web usage behaviour mode analysis and mining technology taking Web news as object of research. The author elaborates main function and method proposed in this model, which include the analysis module of Web news instance clicking mode, the analysis module of Web news instance retrieval mode, the analysis module of Web news instance seed and the analysis module of similar Web news instance supporting topics. Based on these functions and methods, the author elaborates main algorithm proposed in this model, which include the mining algorithm of Web news seed instances and the mining algorithm of similar Web news instances supporting topics. These functional algorithms have been applied in processing module of model, and focus on how to detect network topic efficiently from a large number of web usage behaviour towards to Web news instances, in order to explore a research method for network topic detection. The process of experimental analysis includes three steps, firstly, the author analyses the precision of topic detection under different method, secondly, the author completes the impact analysis of Web news topic detection quality from the number of Web news instances concerned and seed threshold, finally, the author completes the quality impact analysis of Web news instances mined supporting topic from the number of Web news instances concerned and probability threshold. The results of experimental analysis show the feasibility, validity and superiority of model design and play an important role in constructing topic-focused Web news corpus so as to provide a real-time data source for topic evolution tracking.\",\n \"Title: Fastrack: A Modular Framework For Fast And Guaranteed Safe Motion Planning\\nYear: 2017\\n\\nAbstract: Fast and safe navigation of dynamical systems through a priori unknown cluttered environments is vital to many applications of autonomous systems. However, trajectory planning for autonomous systems is computationally intensive, often requiring simplified dynamics that sacrifice safety and dynamic feasibility in order to plan efficiently. Conversely, safe trajectories can be computed using more sophisticated dynamic models, but this is typically too slow to be used for real-time planning. We present the new algorithm FaSTrack: Fast and Safe Tracking. A path or trajectory planner using simplified dynamics to plan quickly can be incorporated into the FaSTrack framework, which provides a safety controller for the vehicle along with a guaranteed tracking error bound. This bound captures all possible deviations due to high dimensional dynamics and external disturbances. FaSTrack is modular and can be used with most current path or trajectory planners. We demonstrate this framework using a 10D nonlinear quadrotor model tracking a 3D path obtained from an RRT planner.\",\n \"Title: Research on Data Visualization in Different Scenarios.\\nYear: 2018\\n\\nAbstract: With the development of computer science, the era of big data has arrived. Facing the new era and new challenges, the traditional analytical methods of problems in various fields have been unable to meet the needs. Data visualization is a rapidly developing discipline, it has significant advantages in analyzing problems, so data visualization shines in the era of big data. As people are very concerned about the fields of energy and environment, we choose to conduct data visualization studies in two areas, energy and the environment. According to the different characteristics of data in different fields, we propose targeted data visualization processes and design data visualization solutions. For energy data, we follow the process of data processing, visualization design, and data visualization. Based on the principle of high efficiency and intuitiveness, we add timeline and a combination of various charts to our design, and finally show a dynamic effect. We also propose a multi-dimensional visual mapping visualization scheme. The scheme can refine and enrich the visual results. For environmental data, we follow the process of goal analysis, data processing, visualization and analysis, the work shows the importance of visualization in information analysis and decision-making.\",\n \"Title: Dynamical Effects Of Neuron Activation Gradient On Hopfield Neural Network: Numerical Analyses And Hardware Experiments\\nYear: 2019\\n\\nAbstract: Hyperbolic tangent function, a bounded monotone differentiable function, is usually taken as a neuron activation function, whose activation gradient, i.e. gain scaling parameter, can reflect the response speed in the neuronal electrical activities. However, the previously published literatures have not yet paid attention to the dynamical effects of the neuron activation gradient on Hopfield neural network (HNN). Taking the neuron activation gradient as an adjustable control parameter, dynamical behaviors with the variation of the control parameter are investigated through stability analyses of the equilibrium states, numerical analyses of the mathematical model, and experimental measurements on a hardware level. The results demonstrate that complex dynamical behaviors associated with the neuron activation gradient emerge in the HNN model, including coexisting limit cycle oscillations, coexisting chaotic spiral attractors, chaotic double scrolls, forward and reverse period-doubling cascades, and crisis scenarios, which are effectively confirmed by neuron activation gradient-dependent local attraction basins and parameterspace plots as well. Additionally, the experimentally measured results have nice consistency to numerical simulations.\",\n \"Title: New observation on the key schedule of RECTANGLE\\nYear: 2019\\n\\nAbstract: We evaluate the security of RECTANGLE from the perspective of actual key information (AKI). Insufficient AKI permits the attackers to deduce some subkey bits from some other subkey bits, thereby lowering the overall attack complexity or getting more attacked rounds. By considering the interaction between the key schedule’s diffusion and the round function’s diffusion, we find there exists AKI insufficiency in 4 consecutive rounds for RECTANGLE-80 and 6 consecutive rounds for RECTANGLE-128, although the master key bits achieve complete diffusion in 2 and 4 rounds, respectively. With such weakness of the key schedule, we give a generic meet-in-the-middle attack on 12-round reduced RECTANGLE-128 with only 8 known plaintexts. Moreover, we calculate AKI of variants of RECTANGLE as well as PRESENT. Surprisingly we find that both RECTANGLE-128 and PRESENT-128 with no key schedule involve more AKI than the original one. Based on this finding, we slightly modify the key schedule of RECTANGLE-128. Compared with the original one, this new key schedule matches better with the round function in terms of maximizing AKI. Our work adds more insight to the design of block ciphers’ key schedule.\",\n \"Title: TTR-Based Rewards for Reinforcement Learning with Implicit Model Priors.\\nYear: 2019\\n\\nAbstract: Model-free reinforcement learning (RL) provides an attractive approach for learning control policies directly in high dimensional state spaces. However, many goal-oriented tasks involving sparse rewards remain difficult to solve with state-of-the-art model-free RL algorithms, even in simulation. One of the key difficulties is that deep RL, due to its relatively poor sample complexity, often requires a prohibitive number of trials to obtain a learning signal. We propose a novel, non-sparse reward function for robotic RL tasks by leveraging physical priors in the form of a time-to-reach (TTR) function computed from an approximate system dynamics model. TTR functions come from the optimal control field and measure the minimal time required to move from any state to the goal. However, TTR functions are intractable to compute for complex systems, so we compute it in a lower-dimensional state space, and then do a simple transformation to convert it into a TTR-based reward function for the MDP in RL tasks. Our TTR-based reward function provides highly-informative rewards that account for system dynamics.\",\n \"Title: The Development And Performance Evaluation Of Digital Museums Towards Second Classroom Of Primary And Secondary School - Taking Zhejiang Education Technology Digital Museum As An Example\\nYear: 2019\\n\\nAbstract: Currently, visiting museums is one activity that gaining its popularity from primary and secondary school students, which makes museum an important part of second classroom. However, this kind of educational activity is limited by several factors such as transportation, time and space, etc., which result in several defects such as limited visiting efficiency, lacks of evaluation for teaching achievements etc. To solve these problems, we put forward a countermeasure program of digital museums towards second classroom for primary and secondary school students. First, we analyzed the studies of second classroom based on the digital museums both in China and other countries. On the basis of such analysis, we took Zhejiang Education Technology Museum as a template to design and develop Zhejiang Education Technology Digital Museum. Then we used theory of pairing design to study the performance of the traditional museum education and the digital museum education respectively. Finally, we evaluated users' experience of Zhejiang Education Technology Digital Museum by carrying out a questionnaire survey.\",\n \"Title: Flux-Charge Analysis of Two-Memristor-Based Chua's Circuit: Dimensionality Decreasing Model for Detecting Extreme Multistability\\nYear: 2020\\n\\nAbstract: In this paper, from a new perspective of flux and charge, we present in-depth analyses of two ideal memristor emulators and the fifth-order memristive Chua's circuit constructed based on them. The constitutive flux–charge relations of the two adopted memristor emulators are first formulated, and their initial-dependent characteristics are numerically revealed and experimentally verified. Thereafter, with these two constitutive relations, a third-order dimensionality decreasing flux–charge model for the fifth-order memristive Chua's circuit is constructed, in which five extra constant system parameters are introduced to indicate the initial states of the five dynamic elements. Numerical simulations confirm that this newly constructed model possesses several determined equilibria and maintains the initial-dependent dynamics of the original voltage–current model. Thus, the complex and sensitive initial state-related extreme multistability phenomenon can be deeply explored through theoretical analyses and hardware measurements. It is demonstrated that the sensitive extreme multistability phenomenon becomes detectable in the flux–charge domain, which is efficient for exploring the inner mechanisms and further seeking possible applications of this special phenomenon.\",\n \"Title: Robust Sequential Trajectory Planning Under Disturbances and Adversarial Intruder\\nYear: 2019\\n\\nAbstract: Provably safe and scalable multivehicle trajectory planning is an important and urgent problem. Although this problem has been studied in the past, there has not been a method that guarantees both goal satisfaction and safety for vehicles with general nonlinear dynamics, while taking into account disturbances and potential adversarial agents, to the best of our knowledge. Hamilton–Jacobi (HJ) reachability is the ideal tool for guaranteeing goal satisfaction and safety under such scenarios, which has been successfully applied to many small-scale problems; however, its direct application in most cases becomes intractable when there are more than two vehicles due to the exponentially scaling computational complexity with respect to system dimension. In this paper, we take advantage of the guarantees provided by HJ reachability and eliminate the computation burden by assigning a strict priority ordering to vehicles under consideration. Under this sequential trajectory planning (STP) scheme, vehicles reserve “space–time” portions in the airspace. The space–time portions guarantee dynamic feasibility, collision avoidance, and optimality of trajectories given the priority ordering. With a computation complexity that scales quadratically when accounting for both disturbances and an intruder, and \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">linearly</italic>\\n when accounting for only disturbances, the STP can tractably solve the multivehicle trajectory planning problem for vehicles with general nonlinear dynamics in a practical setting. We demonstrate our theory in representative simulations.\",\n \"Title: Brain network reconfiguration for language and domain-general cognitive control in bilinguals.\\nYear: 2019\\n\\nAbstract: For bilinguals, language control is needed for selecting the target language during language production. Numerous studies have examined the neural correlates of language control and shown a close relationship between language control and domain-general cognitive control. However, it remains unknown how these brain regions coordinate with each other when bilinguals exert cognitive control over linguistic and nonlinguistic representations. We addressed this gap using an extended unified structural equation modeling (euSEM) approach. Sixty-five Chinese-English bilinguals performed language switching and nonverbal switching tasks during functional magnetic resonance imaging (fMRI) scanning. The results showed that language control was served by a cooperative brain network, including the frontal lobe, the parietal cortex, subcortical areas, and the cerebellum. More importantly, we found that language control recruited more subcortical areas and connections from frontal to subcortical areas compared with domain-general cognitive control, demonstrating a reconfigurable brain network. In addition, the reconfiguration efficiency of the brain network was mainly determined by general cognitive ability but was also mediated by second language (L2) proficiency. These findings provide the first data-driven connectivity model that specifies the brain network for language control in bilinguals and also shed light on the relationship between language control and domain-general cognitive control.\",\n \"Title: Research On Key Technology Of Web Hierarchical Topic Detection And Evolution Based On Behaviour Tracking Analysis\\nYear: 2019\\n\\nAbstract: In the development background of today's big data era, the research direction of Web hierarchical topic detection and evolution characterized by the semi-structured or unstructured data has caught wide attention for academicians. This paper proposes an idea of Web hierarchical topic detection and evolution based on behaviour tracking analysis taking the network big data as the research object, and expounds main implementation methods, which include the instance analysis of the usage mode, the instance analysis of the seed, the set analysis of similar instance supporting the topics, the set analysis of similar instance supporting the events, the evolution analysis of the event, and expounds the algorithm of Web hierarchical topic detection and evolution based on behaviour tracking analysis. The process of experimental analysis is organized as follows, first of all, the experiment analyses the quality of topic detection, the accuracy rate with the number of instance concerned and the seed threshold variation trend, the accuracy rate with the number of instance concerned and the probability threshold variation trend, secondly, the experiment analyses the quality of topic evolution, the accuracy rate with the variation trend of parameter adjustment, the accuracy rate with the number of instance concerned and the similar threshold variation trend, finally, the experiment analyses the time consuming to solve main research problem under different method, the qualitative result of topic detection and evolution under different data set. The results of experimental analysis show the idea is feasible, verifiable and superior, which plays a major role in reconfiguring Web hierarchical topic corpus and providing an intelligent big data warehouse for the network information evolution application.\",\n \"Title: Reference Channels for Steganalysis of Images with Convolutional Neural Networks.\\nYear: 2019\\n\\nAbstract: When available, reference signals may dramatically improve the accuracy of steganalysis. Particularly powerful reference signals are embedding invariants that exist when the steganographic algorithm swaps values from small disjoint subsets of the cover elements' dynamic range, such as, but not limited to, embedding schemes utilizing least significant bit replacement. This paper describes a general method how to prepare such reference signals for a certain type of embedding operations, and incorporate them in detectors built as convolutional networks to improve their detection accuracy. The beneficial effect of reference signals is shown experimentally in both the spatial and especially JPEG domain, on model-based steganography and a generic LSB flipper with and without stochastic restoration of the histogram (OutGuess).\",\n \"Title: Hybrid State Variable Incremental Integral for Reconstructing Extreme Multistability in Memristive Jerk System with Cubic Nonlinearity.\\nYear: 2019\\n\\nAbstract: Memristive system with infinitely many equilibrium points has attracted much attention for the generation of extreme multistability, whose initial-dependent dynamics can be interpreted in a reduced-order model through incremental integral transformation of state variables. But, the memristive system with any extra nonlinear terms besides the memristor ones cannot be handled directly using this method. In addition, the transformed state variables could be divergent due to the asymmetry of the original system. To solve these problems, a hybrid state variable incremental integral (HSVII) method is proposed in this paper. With this method, the extreme multistability in a four-dimensional (4D) memristive jerk system with cubic nonlinearity is successfully reconstituted in a three-dimensional (3D) model and the divergent state variables are eliminated through ingenious linear state variable mapping. Thus, mechanism analysis and physical control of the special extreme multistability can readily be performed. A hardware circuit is finally designed and fabricated, and the theoretical and numerical results are verified by the experimental measurements. It is demonstrated that this HSVII method is effective for the analysis of multistable system with high-order nonlinearities.\",\n \"Title: Blacklists and Redlists in the Chinese Social Credit System: Diversity, Flexibility, and Comprehensiveness\\nYear: 2021\\n\\nAbstract: The Chinese Social Credit System (SCS) is a novel digital socio-technical credit system. The SCS aims to regulate societal behavior by reputational and material devices. Scholarship on the SCS has offered a variety of legal and theoretical perspectives. However, little is known about its actual implementation. Here, we provide the first comprehensive empirical study of digital blacklists (listing \\\"bad\\\" behavior) and redlists (listing \\\"good\\\" behavior) in the Chinese SCS. Based on a unique data set of reputational blacklists and redlists in 30 Chinese provincial-level administrative divisions (ADs), we show the diversity, flexibility, and comprehensiveness of the SCS listing infrastructure. First, our results demonstrate that the Chinese SCS unfolds in a highly diversified manner: we find differences in accessibility, interface design and credit information across provincial-level SCS blacklists and redlists. Second, SCS listings are flexible. During the COVID-19 outbreak, we observe a swift addition of blacklists and redlists that helps strengthen the compliance with coronavirus-related norms and regulations. Third, the SCS listing infrastructure is comprehensive. Overall, we identify 273 blacklists and 154 redlists across provincial-level ADs. Our blacklist and redlist taxonomy highlights that the SCS listing infrastructure prioritizes law enforcement and industry regulations. We also identify redlists that reward political and moral behavior. Our study substantiates the enormous scale and diversity of the Chinese SCS and puts the debate on its reach and societal impact on firmer ground. Finally, we initiate a discussion on the ethical dimensions of data-driven research on the SCS.\",\n \"Title: Integrated Optimization of Train Speed Profile and Timetable Considering the Location of Substations\\nYear: 2021\\n\\nAbstract: Adjusting the timetable and speed profile of trains can bring significant reduction in energy consumption, which is almost zero cost to the subway operating company. This paper proposes an integrated optimization method for a single train, to simultaneously obtain the optimal speed profile and the interstation trip time distribution of the whole journey by dynamic programming (DP). With modeling t...\",\n \"Title: Optimal shape morphing control of 4D printed shape memory polymer based on reinforcement learning\\nYear: 2022\\n\\nAbstract: 4D printing technology, as a new generation of Additive Manufacturing methods, enables printed objects to further change their shapes or other properties upon external stimuli. One main category of 4D printing research is 4D printed thermal Shape Memory Polymer (SMP). Its morphing process has large time delay, is nonlinear time variant, and susceptible to unpredictable disturbances. Reaching an arbitrary position with high precision is an active research question. This paper applies the Reinforcement Learning (RL) method to develop an optimal control method to perform closed loop control of the SMP actuation. Precise and prompt shape morphing is achieved compared with previous control methods using a PI controller. The training efforts of RL are further reduced by simplifying the optimal control policy using the structural property of the prior trained results. Customized protective visors against COVID-19 are fabricated using the proposed control method.\",\n \"Title: Discrete Memristor Hyperchaotic Maps\\nYear: 2021\\n\\nAbstract: Regarding as a basic circuit component with special nonlinearity, memristor has been widely applied in chaotic circuits and neuromorphic circuits. However, discrete memristor (DM) has not been received much attention, yet. To this end, this paper reports a general DM model and its unified mapping model. Using the general DM model, four representations of DMs are given and their pinched hysteresis ...\",\n \"Title: Coexisting Infinitely Many Nonchaotic Attractors In A Memristive Weight-Based Tabu Learning Neuron\\nYear: 2021\\n\\nAbstract: Memristive synaptic weight is a changeable connection synaptic weight. It reflects the self-adaption physical processing in biological neurons. To study its dynamical effect, this paper presents a memristive synaptic weight-based tabu learning neuron model. It is constructed by replacing the resistive self-connection synaptic weight in the tabu learning neuron with a memristive self-connection synaptic weight. The equilibrium point of the memristive tabu learning model is time-varying and switches between no equilibrium state and line equilibrium state with the change of the external current. Particularly, the stability of the line equilibrium state closely relies on the initial state of the memristor, resulting in the emergence of coexisting infinitely many nonchaotic attractors. By employing the bifurcation plots, Lyapunov exponents, and phase plots, this paper numerically reveals the initial state-switched coexisting bifurcation behaviors and initial state-relied extreme multistability, and thereby discloses the coexisting infinitely many nonchaotic attractors composed of mono-periodic, multiperiodic, and quasi-periodic orbits. In addition, PSIM circuit simulations and printed-circuit board-based experiments are executed and the coexisting infinitely many nonchaotic attractors are realized physically. The results well verify the numerical simulations.\",\n \"Title: Initial-condition-switched boosting extreme multistability and mechanism analysis in a memcapacitive oscillator\\nYear: 2021\\n\\nAbstract: Extreme multistability has seized scientists' attention due to its rich diversity of dynamical behaviors and great flexibility in engineering applications. In this paper, a four-dimensional (4D) memcapacitive oscillator is built using four linear circuit elements and one nonlinear charge-controlled memcapacitor with a cosine inverse memcapacitance. The 4D memcapacitive oscillator possesses a line equilibrium set, and its stability periodically evolves with the initial condition of the memcapacitor. The 4D memcapacitive oscillator exhibits initial-condition-switched boosting extreme multistability due to the periodically evolving stability. Complex dynamical behaviors of period doubling/halving bifurcations, chaos crisis, and initial-condition-switched coexisting attractors are revealed by bifurcation diagrams, Lyapunov exponents, and phase portraits. Thereafter, a reconstructed system is derived via integral transformation to reveal the forming mechanism of the initial-condition-switched boosting extreme multistability in the memcapacitive oscillator. Finally, an implementation circuit is designed for the reconstructed system, and Power SIMulation (PSIM) simulations are executed to confirm the validity of the numerical analysis.\",\n \"Title: Real-Time Hamilton-Jacobi Reachability Analysis of Autonomous System With An FPGA\\nYear: 2021\\n\\nAbstract: Hamilton-Jacobi (HJ) reachability analysis is a powerful technique used to verify the safety of autonomous systems. HJ reachability is ideal for analysing nonlinear systems with disturbances and flexible set representations. A drawback to this approach is that it suffers from the curse of dimensionality, which prevents real-time deployment on safety-critical systems. In this paper, we show that a customized hardware design on an Field Programmable Gate Array (FPGA) could accelerate 4D grid-based HJ reachability analysis up to 14 times compared to an optimized implementation and 103 times compared to state-of-the-art MATLAB toolboxes on a 16-thread CPU. Because of this, we are able to achieve guaranteed real-time collision avoidance in dynamic environments that abruptly change with a 4D car model by re-solving the HJ partial differential equation (PDE) at a frequency of 4Hz on an FPGA. Our design can overcome the complex data access pattern while taking advantage of the parallel nature of the computations for solving the HJ PDE. The low latency of our computation is consistent, which is crucial for safety-critical systems. The methodology presented here is without loss of generality: it can potentially be applied to different systems dynamics, and moreover, leveraged for higher dimensional systems. We validate our approach in real world collision avoidance experiments with a robot car in a changing environment. We also provide the code of our hardware design and an AWS AFI image.\",\n \"Title: A Multimodal and Hybrid Framework for Human Navigational Intent Inference\\nYear: 2021\\n\\nAbstract: Understanding human navigational intent is essential for robots to be able to interact with and navigate around humans safely and naturally. Current methods typically perform inference through only one mode of perception such as human motion trajectory, and a single theoretical framework such as a learning-based or classical approach. In contrast, this paper studies prediction of human navigational intent using multimodal perception within a hybrid framework. Our framework consists of two modules: a) a learning-based prediction module to predict a human's future goal position, and b) a classical control theory-inspired reconstruction module to reconstruct a possible future trajectory or a set of possible future positions using the predicted future goal position. For the prediction module, we propose an end-to-end LSTM-CNN hybrid neural network for predicting a human's future position in the real world, given human motion, human body pose and head orientation. This visual information from an egocentric perspective is used to make predictions of a human's future position in world space, essential for robotic navigation algorithms and planning. In the reconstruction module, we present two control theoretic methods to reconstruct possible future trajectories of human: trajectory generation for differentially flat system and reachability analysis. We evaluate the performance of our framework on a newly collected dataset called SFU-Store-Nav. Experimental results reveal that our method outperforms various baselines especially when a relatively small amount of data is available.\",\n \"Title: Finite-Time Synchronization for Fuzzy Delayed Neutral-Type Inertial Bam Neural Networks Via the Figure Analysis Approach\\nYear: 2022\\n\\nAbstract: This paper focuses on the finite-time synchronization for fuzzy delayed neutral-type inertial BAM neural networks. Without making the variable transformation, the inertial system was analyzed directly. By applying integral inequality techniques and the figure analysis approach, some novel criteria are achieved to assure the finite-time synchronization between the drive system and the response system. The inequalities used in our paper are different from these in the existing papers. The figure analysis approach used to research finite-time synchronization in our paper is a completely novel study approach.\",\n \"Title: Double-Vector Model-Free Predictive Control Method for Voltage Source Inverter With Visualization Analysis\\nYear: 2022\\n\\nAbstract: Strong parameter dependence and large current ripple are two shortcomings that obstruct the development of model predictive control for voltage source inverters (VSIs). To solve these problems, in this article,a double-vector model-free predictive control (MFPC) method for VSI with visualization analysis is proposed. First, the ultralocal model of the VSI is established and a full-order sliding mo...\",\n \"Title: Piecewise-Linear Simplification for Adaptive Synaptic Neuron Model\\nYear: 2022\\n\\nAbstract: Adaptive synaptic neuron model involves complex activation functions. These nonlinearities lead to complicated hardware implementations, which greatly hinder neuron-based applications. To effectively solve this issue, a piecewise-linear (PWL) activation function with simplified circuit implementation is presented for the adaptive synaptic neuron model in this brief. With this neuron model, the stability evolution mechanism of the equilibrium state is analyzed and the parameter- and initial condition-related neuron dynamics are numerically explored. Afterwards, an analog circuit is designed and manually made using commercially available components. The phase trajectories captured by the hardware experiments verify the feasibility of the PWL activation function. Thus, such a PWL simplification shows superiority in emulating neuron dynamics.\",\n \"Title: Applications of affordance and cognitive ergonomics in virtual design: A digital camera as an illustrative case\\nYear: 2022\\n\\nAbstract: Affordance-based design (ABD) plays an important role in identifying interactions, especially effortless ones, between users and artifacts. Cognitive ergonomics extends our understanding of this effortless interaction. This study combines the two design methodologies together in order to reduce cognitive friction in using digital products. The design process of a compact digital camera is selected as a case study that includes the design of the physical shape for a camera and of its user interface. In designing a product shape, a design toolbox was developed that integrated a modified multi-objective genetic algorithm and the ABD, which was named as affordance-based interactive genetic algorithm. Using this toolbox and interactive user feedback, the camera design evolves toward a product that better satisfies the users. User interfaces (UIs) including linear and elliptic layouts were subsequently designed based on cognitive ergonomics. A predictive tool of UI, the Cog Tool, was used to evaluate the performance of skilled users on a given task by correlating the overall task completion time. Finally, this research has the potential to not only effectively address the shortcomings of the design of consumer electronics but also enrich the generation of design solutions during the preliminary design phase of such products.\",\n \"Title: Memristor-Based Hyperchaotic Maps and Application in Auxiliary Classifier Generative Adversarial Nets\\nYear: 2022\\n\\nAbstract: With the nonlinearity and plasticity, memristors are widely used as nonlinear devices for chaotic oscillations or as biological synapses for neuromorphic computations. But discrete memristors (DMs) and their coupling maps have not received much attention, yet. Using a DM model, this article presents a general three-dimensional discrete memristor-based (3-D-DM) map model. By coupling the DM with fo...\",\n \"Title: Analog/Digital Multiplierless Implementations for Nullcline-Characteristics-Based Piecewise Linear Hindmarsh-Rose Neuron Model\\nYear: 2022\\n\\nAbstract: Multipliers are essential in implementing nonlinear neuron models, but they take huge implementation costs. Many multiplierless fitting schemes have been proposed to simplify the implementation of nonlinearities in neuron models. To optimize these schemes, this paper presents a nullcline-characteristics- based piecewise linear (NC-PWL) fitting scheme for multiplierless implementations of Hindmarsh-Rose (HR) neuron model. This NC-PWL fitting scheme uses as few line segments as possible to approximate the critical nonlinearity characteristics of the local nullclines. A NC-PWL HR neuron model that reproduces diverse firing patterns of the original one is successfully established. Using off-the-shelf low-cost components, an analog multiplierless circuit is designed for this fitting model and welded on print circuit board (PCB). Meanwhile, by logical shift method, a digital multiplierless circuit with low resource consumption is developed for this fitting model on field-programmable gate array (FPGA) platform. Experimental results of the analog and digital multiplierless hardware implementations verify the numerical simulations and show the simplicity and feasibility of the presented fitting scheme.\",\n \"Title: Towards Inclusive HRI: Using Sim2Real to Address Underrepresentation in Emotion Expression Recognition.\\nYear: 2022\\n\\nAbstract: Robots and artificial agents that interact with humans should be able to do so without bias and inequity, but facial perception systems have notoriously been found to work more poorly for certain groups of people than others. In our work, we aim to build a system that can perceive humans in a more transparent and inclusive manner. Specifically, we focus on dynamic expressions on the human face, which are difficult to collect for a broad set of people due to privacy concerns and the fact that faces are inherently identifiable. Furthermore, datasets collected from the Internet are not necessarily representative of the general population. We address this problem by offering a Sim2Real approach in which we use a suite of 3D simulated human models that enables us to create an auditable synthetic dataset covering 1) underrepresented facial expressions, outside of the six basic emotions, such as confusion; 2) ethnic or gender minority groups; and 3) a wide range of viewing angles that a robot may encounter a human in the real world. By augmenting a small dynamic emotional expression dataset containing 123 samples with a synthetic dataset containing 4536 samples, we achieved an improvement in accuracy of 15% on our own dataset and 11% on an external benchmark dataset, compared to the performance of the same model architecture without synthetic training data. We also show that this additional step improves accuracy specifically for racial minorities when the architecture's feature extraction weights are trained from scratch.\",\n \"Title: PolarDB-X: An Elastic Distributed Relational Database for Cloud-Native Applications\\nYear: 2022\\n\\nAbstract: Cloud computing is on the rise, which promotes new breeds of database systems to accommodate the cloud environment. The development of cloud-native databases reveals three trends. One is the adoption of multi-datacenter (DC) deployment to survive the downtime of any single site. Another is the separation of computation and storage resources to achieve higher elasticity and scalability. The last is the support of HTAP to eliminate data redundancy and system complexity from heterogeneous databases. To cater to these trends, we design a distributed relational database called PolarDB-X, which is built on top of the cloudnative database PolarDB. It hence inherits many cloud-native features, such as multi-datacenter deployment and elasticity. To achieve cross-DC capability, it leverages Paxos and hybrid logical clock to achieve durability and snapshot-isolation consistency with low coordination costs. For resource elasticity, since the underlying PolarDB supports rapid migration of tenants between nodes, PolarDB-X can quickly scale the cluster to cope with a sudden traffic increase. For HTAP support, with the help of read replicas and a HTAP executor, PolarDB-X can improve the latency and parallelism of analytical queries without impacting concurrently-running TP workloads. Using its MPP engine and an in-memory column index, the efficiency of analytical queries can be further enhanced. PolarDB-X is now a cloud database service at Alibaba Cloud. We have learned many useful lessons from its development and operation, and have incorporated those into our design and analysis.\",\n \"Title: Real-time Mapping of Multi-Floor Buildings Using Elevators\\nYear: 2022\\n\\nAbstract: This paper discusses the creation of a map of multi-floor buildings using elevators in autonomous and manual driving modes. Two disadvantages of existing Simultaneous Localization And Mapping (SLAM) algorithms are inability to detect elevation change and drift inside reflective environments such as many modern elevators. Therefore, we integrate the LeGO-LOAM SLAM algorithm with air pressure data collected by a barometric pressure sensor to create a map of a multi-story building in real-time without losing track of robot’s movement inside an elevator. To achieve this, we developed an elevator detection module to detect elevators using a depth camera and locate them in floor maps. In autonomous driving mode, after exploring and mapping one floor, the robot autonomously navigates to the detected elevator, takes it to another floor, and starts mapping the new floor without losing track of the robot’s position despite sudden changes in the environment during this process. The manual driving mode is subsequently added to evaluate the performance of the system and the accuracy of the generated map. The experimental results show that the proposed algorithm is capable of mapping multiple floors autonomously and manually with minimal drift.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":125,"string":"125"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":43,"string":"43"}}},{"rowIdx":44,"cells":{"question_id":{"kind":"string","value":"Stark C Draper"},"question":{"kind":"string","value":"Generate an abstract for the title \"Second-order coding rate for m-class source-channel codes.\" using the following items: 1. Second-order coding rate \n2. Unequal message protection (UMP) \n3. Optimization problem \n4. Procedure \n5. Numerical results"},"answer":{"kind":"string","value":"The second-order coding rate for source-channel codes with m levels of unequal message protection (UMP) is derived. The second-order coding rate takes the form of an optimization problem which reduces to separate source-channel coding rate for m = 2. A procedure for solving the given optimization problem is proposed. The proposed procedure exploits the structure of the problem to reduce the optimization search space to one dimension. Numerical results for the BSC are obtained and it is shown, empirically, that the second-order coding rate of source-channel codes with m levels of UMP approaches the optimal joint source-channel coding rate as m grows."},"correct_answer":{"kind":"string","value":"The second-order coding rate for source-channel codes with m levels of unequal message protection (UMP) is derived. The second-order coding rate takes the form of an optimization problem which reduces to separate source-channel coding rate for m = 2. A procedure for solving the given optimization problem is proposed. The proposed procedure exploits the structure of the problem to reduce the optimization search space to one dimension. Numerical results for the BSC are obtained and it is shown, empirically, that the second-order coding rate of source-channel codes with m levels of UMP approaches the optimal joint source-channel coding rate as m grows."},"documents":{"kind":"list like","value":["Title: Universal Anytime Coding\nYear: 2007\n\nAbstract: We show the existence of codes for anytime coding over compound channels - i.e. codes that operate without knowledge of the transition probabilities of the communication channel. The anytime error exponent achieved is the same as if the decoder were given the probabilities governing the realized channel and allowed to do maximum likelihood decoding. Because of the equivalence between system stabilization over noisy feedback channels and communication over noisy channels, the results immediately give sufficient conditions for stabilization over compound channels.","Title: Notary: Hardware techniques to enhance signatures\nYear: 2008\n\nAbstract: Hardware signatures have been recently proposed as an efficient mechanism to detect conflicts amongst concurrently running transactions in transactional memory systems (e.g., Bulk, LogTM-SE, and SigTM). Signatures use fixed hardware to represent an unbounded number of addresses, but may lead to false conflicts (detecting a conflict when none exists). Previous work recommends that signatures be implemented with parallel Bloom filters with two or four hash functions (e.g., H3).","Title: Minimizing total area of low-voltage SRAM arrays through joint optimization of cell size, redundancy, and ECC\nYear: 2010\n\nAbstract: The increasing power consumption of processors has made power reduction a first-order priority in their design. Voltage scaling is one of the most successful power-reduction techniques introduced to date, but it is limited to some minimum voltage, VDDMIN, below which all components cannot operate reliably. In particular, ever-increasing process variability due to shrinking feature size further degrades the low-voltage reliability of, e.g., SRAM cells. Larger SRAM cells are less sensitive to process variability and their use would allow a reduction in VDDMIN. However, large-scale memory structures, e.g., last-level caches (LLCs) that often determine the VDDMIN of processors, cannot afford to use such large SRAM cells due to the resulting increase in die area. In this paper we propose a joint optimization of LLC cell size, number of redundant cells, and ECC (error-correction coding) strength to minimize total SRAM area while meeting target yields and VDDMIN. The use of redundant cells and ECC enable the use of smaller cell sizes while maintaining target yields and VDDMIN. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. We first assess each approach individually, i.e., only redundancy or ECC for various cell sizes. We then consider a combined approach and observe significant improvements. For example, in 32nm technology our combined approach yields a 27% reduction in total SRAM area (including redundant cells) when targeting a VDDMIN of 600mV.","Title: On Compression of Encrypted Video\nYear: 2007\n\nAbstract: We consider video sequences that have been encrypted uncompressed. Since encryption masks the source, traditional data compression algorithms are rendered ineffective. However, it has been shown that through the use of distributed source-coding techniques, the compression of encrypted data is in fact possible. This means that it is possible to reduce data size without requiring that the data be compressed prior to encryption. Indeed, under some reasonable conditions, neither security nor compression efficiency need be sacrificed when compression is performed on the encrypted data (Johnson et al., 2004). In this paper we develop an algorithm for the practical lossless compression of encrypted gray scale video. Our method is based on considering the temporal correlations in video. This move to temporal dependence builds on our previous work on memoryless sources, and one- and two-dimensional Markov sources. For comparison, a motion-compensated lossless video encoder can compress each unencrypted frame of the standard \"Foreman test video sequence by about 57%. Our algorithm can compress compress the same frames, after encryption, by about 33%.","Title: QUEUING WITH DISTORTION-CONTROL FOR MULTIMEDIA CONTENT\nYear: 2002\n\nAbstract: There are numerous contexts in which systems need to buffer multimedia signal content. If such a buffer overflo ws, sig- nal data are lost in an uncontrolled manner, which can lead to large end-to-end distortions. However, if the queued sig- nals are distortion-tolerant, overflo ws can be avoided, and significant performance gains realized, by reducing the fi- delity of the signals in a gradual, controlled, manner. Based on ideas of successive-approximation source coding, we de- sign an adaptive-buffering algorithm to minimize end-to- end distortion. This algorithm performs nearly as well as a performance bound on all possible algorithms. Perhaps most importantly, the algorithm' s performance remains ro- bust across a wide range of (unpredictable) utilization rates (input rate/output rate).","Title: On reliability of content identification from databases based on noisy queries.\nYear: 2011\n\nAbstract: In this paper we quantify an achievable error-exponent for the problem of content identification from a large database based on noisy queries.","Title: Secret key generation through OFDM multipath channel\nYear: 2011\n\nAbstract: We analyze the fundamental limits of key generation and describe an implementation based on error correcting codes. We show that key extraction based on channel coefficients significantly outperforms key extraction based on received signal strength indicators (RSSI). The development in this paper is based on an IEEE 802.11a orthogonal frequency-division multiplexing (OFDM) model and We demonstrate that it is feasible to use the sampled channel coefficients in OFDM as the key source. The key extraction problem is cast as a Slepian-Wolf coding and decoding problem. We construct regular and irregular forms of binary and non-binary low-density parity check (LDPC) codes to prototype our key extraction.","Title: Queuing theoretic analysis of power-performance tradeoff in power-efficient computing\nYear: 2013\n\nAbstract: In this paper we study the power-performance relationship of power-efficient computing from a queuing theoretic perspective. We investigate the interplay of several system operations including processing speed, system on/off decisions, and server farm size. We identify that there are oftentimes 'sweet spots' in power-efficient operations: there exist optimal combinations of processing speed and system settings that maximize power efficiency. For the single server case, a widely deployed threshold mechanism is studied. We show that there exist optimal processing speed and threshold value pairs that minimize the power consumption. This holds for the threshold mechanism with job batching. For the multi-server case, it is shown that there exist best processing speed and server farm size combinations.","Title: An analysis of empirical PMF based tests for least significant bit image steganography\nYear: 2005\n\nAbstract: We consider here the class of probability mass-function (PMF) based detectors of least significant bit (LSB) embedded steganography. That is, in this paper we investigate the use of frequency counts of pixel intensities as a statistic for tests detecting the presence of hidden messages. We focus on LSB replacement (though we briefly consider LSB matching) embedding as it is a simple technique where the effect on the true PMF of the resulting image can be understood mathematically. We begin our study by considering the existing tests of Westfeld and Pfitzmann [11] and Dabeer et al.[1]. These tests assume that pixel intensities are random values that are independent and identically distributed (i.i.d.). We generalize these tests by considering PMFs of neighboring pixel intensities. We argue that consideration of higher order of correlations provide only diminishing marginal returns, and thus we can make general statements on the value of PMF based detectors. We measure the performance of our tests by calculation of receiver operating curves (ROC) over a corpus of 350 digital images. We then proceed to compare to a non-PMF based test, in particular the RS tests of Fridrich et al [3]. Although our generalized tests outperform existing PMF based predecessors, they are outperformed by the RS tests. This indicates that using PMFs as a statistic for detecting hidden messages is inherently insufficient.","Title: Unequal Message Protection: Asymptotic and Non-Asymptotic Tradeoffs.\nYear: 2014\n\nAbstract: We study a form of unequal error protection that we term unequal message protection (UMP). The message set of a UMP code is a union of m disjoint message classes. Each class has its own error protection requirement, with some classes needing better error protection than others. We analyze the tradeoff between rates of message classes and the levels of error protection; our analysis reveals new tradeoffs, which were not captured by prior works on UMP codes. To obtain our results, we generalize finite block length achievability and converse bounds due to Polyanskiy-Poor-Verdú. We evaluate our bounds for the binary symmetric and binary erasure channels, and analyze the asymptotic characteristic of the bounds in the fixed error and moderate deviations regimes. In addition, we consider two questions related to the practical construction of UMP codes. First, we study a header construction that prefixes the message class into a header followed by data protection using a standard homogeneous (classical) code. We show that, in general, this construction is not optimal at finite block lengths. We further demonstrate that our main UMP achievability bound can be obtained using coset codes, which suggests a path to implementation of tractable UMP codes.","Title: Cooperative Packet Routing using Mutual Information Accumulation\nYear: 2011\n\nAbstract: We consider the resource allocation problem in cooperative wireless networks wherein nodes perform mutual information accumulation. We consider a unicast setting and arbitrary arrival processes at the source node. Source arrivals can be broken down into numerous packets to better exploit the spatial and temporal diversity of the routes available in the network. We devise a linear-program-based algorithm which allocates network resource to meet a certain transmission objective. Given a network, a source with multiple arriving packets and a destination, our algorithm generates a policy that regulates which nodes should participate in transmitting which packets, when and with what resource. By routing different packets through different nodes the policy exploits spatial route diversity, and by sequencing packet transmissions along the same route it exploits temporal route diversity.","Title: Divide and Concur and Difference-Map BP Decoders for LDPC Codes\nYear: 2011\n\nAbstract: The “Divide and Concur” (DC) algorithm introduced by Gravel and Elser can be considered a competitor to the belief propagation (BP) algorithm, in that both algorithms can be applied to a wide variety of constraint satisfaction, optimization, and inference problems. We show that DC can be interpreted as a message-passing algorithm on a “normal” factor graph. The “difference-map” dynamics of the DC algorithm enables it to avoid “traps” which may be related to the “trapping sets” or “pseudo-codewords” that plague BP decoders of low-density parity check (LDPC) codes in the error-floor regime. We investigate two decoders for LDPC codes based on these ideas. The first decoder is based directly on DC, while the second decoder borrows the important “difference-map” concept from the DC algorithm and translates it into a BP-like decoder. We show that this “difference-map belief propagation” (DMBP) decoder has dramatically improved error-floor performance compared to standard BP decoders, while maintaining a similar computational complexity. We present simulation results for LDPC codes comparing DC and DMBP decoders with other decoders based on sum-product BP, linear programming, and mixed-integer linear programming. We also describe the close relation of the DMBP decoder to reweighted min-sum algorithms, including those recently proposed by Ruozzi and Tatikonda.","Title: Optimal scheduling policies with mutual information accumulation in wireless networks\nYear: 2012\n\nAbstract: In this paper, we aim to develop scheduling policies to maximize the stability region of a wireless network under the assumption that mutual information accumulation is implemented at the physical layer. This enhanced physical layer capability enables the system to accumulate information even when the link between two nodes is not good and a packet cannot be decoded within a slot. The result is an expansion of the stability region of the system. The accumulation process does not satisfy the i.i.d assumption that underlies many previous analysis in this area. Therefore it also brings new challenges to the problem. We propose two dynamic scheduling algorithms to overcome this difficulty. One performs scheduling every T slot, which inevitably increases average delay in the system, but approaches the boundary of the stability region. The second constructs a virtual system with the same stability region. Through controlling the virtual queues in the constructed system, we avoid the non-i.i.d difficulty and attain the stability region. We derive performance bounds under both algorithms and compare them through simulation results.","Title: The l1 penalized decoder and its reweighted LP\nYear: 2012\n\nAbstract: Linear programming (LP) decoding for low density parity check (LDPC) codes proposed by Feldman et al. has attracted considerable attention in recent years. Despite having theoretical guarantees in some regimes, at low SNRs LP decoding is observed to have worse error performance than belief propagation (BP) decoding. In this paper, we present a novel decoding algorithm obtained by trying to solve a non-convex optimization problem using the alternating direction method of multipliers (ADMM). This non-convex problem is constructed by adding an ℓ1 penalty term to the LP decoding objective. The goal of the penalty term is to make “pseudocodewords”, which are the non-integer vertices of the LP relaxation to which the LP decoder fails, more costly. We name this the “ℓ1 penalized decoder”. We also develop a reweighted LP decoding algorithm base on this ℓ1 penalized objective. We show that this reweighted LP has an improved theoretical recovery threshold compared to the original LP. In addition, simulations show that, in comparison to LP decoding, these two decoders both achieve significantly lower error rates and are not observed to have an “error floor”. In particular, the ℓ1 penalized decoder meets or outperforms the BP decoder at all SNRs.","Title: Compressed sensing over finite fields\nYear: 2009\n\nAbstract: We develop compressed sensing results for sources drawn from finite alphabets. We apply tools from linear coding and large deviations. We establish strong connections between our results and error exponents of lossless source coding in the case of no measurement noise, and modified channel coding error exponents in the case of measurement noise. We connect to standard results on compressed sensing in the real field.","Title: Exploiting route diversity in multi-packet transmission using mutual information accumulation\nYear: 2011\n\nAbstract: We consider the resource allocation problem in cooperative wireless networks wherein nodes perform mutual information accumulation. We consider a unicast setting and arbitrary arrival processes at the source node. Source arrivals can be broken down into numerous packets to better exploit the spatial and temporal diversity of the routes available in the network. We devise a linear-program-based algorithm which al locates network resource to meet a certain transmission objective. Given a network, a source with multiple arriving packets and a destination, our algorithm generates a policy that regulates which nodes should participate in transmitting which packets, when and with what resource. By routing different packets through different nodes the policy exploits spatial route diversity, and by sequencing packet transmissions along the same route it exploits temporal route diversity.","Title: Hierarchical and High-Girth QC LDPC Codes\nYear: 2013\n\nAbstract: We present an approach to designing capacity-approaching high-girth low-density parity-check (LDPC) codes that are friendly to hardware implementation, and compatible with some desired input code structure defined using a protograph. The approach is based on a mapping of any class of codes defined using a protograph into a family of hierarchical quasi-cyclic (HQC) LDPC codes. Whereas the parity check matrices of standard quasi-cyclic (QC) LDPC codes are composed of circulant submatrices, those of HQC LDPC codes are composed of a hierarchy of circulant submatrices that are, in turn, constructed from circulant submatrices, and so on, through some number of levels. Next, we present a girth-maximizing algorithm that optimizes the degrees of freedom within the family of codes to yield a high-girth HQC LDPC code, subject to bounds imposed by the fact that HQC codes are still quasi-cyclic. Finally, we discuss how certain characteristics of a code protograph will lead to inevitable short cycles and show that these short cycles can be eliminated using a “squashing” procedure that results in a high-girth QC LDPC code, although not a hierarchical one. We illustrate our approach with three design examples of QC LDPC codes—two girth-10 codes of rates $1/3$ and 0.45 and one girth-8 code of rate 0.7—all of which are obtained from protographs of one-sided spatially coupled codes.","Title: A Theoretical Analysis of Authentication, Privacy, and Reusability Across Secure Biometric Systems\nYear: 2011\n\nAbstract: We present a theoretical framework for the analysis of privacy and security trade-offs in secure biometric authentication systems. We use this framework to conduct a comparative information-theoretic analysis of two biometric systems that are based on linear error correction codes, namely fuzzy commitment and secure sketches. We derive upper bounds for the probability of false rejection $(P_{FR})$ and false acceptance $(P_{FA})$ for these systems. We use mutual information to quantify the information leaked about a user's biometric identity, in the scenario where one or multiple biometric enrollments of the user are fully or partially compromised. We also quantify the probability of successful attack $(P_{SA})$ based on the compromised information. Our analysis reveals that fuzzy commitment and secure sketch systems have identical $P_{FR}$ , $P_{FA}$ , $P_{SA}$ , and information leakage, but secure sketch systems have lower storage requirements. We analyze both single-factor (keyless) and two-factor (key-based) variants of secure biometrics, and consider the most general scenarios in which a single user may provide noisy biometric enrollments at several access control devices, some of which may be subsequently compromised by an attacker. Our analysis highlights the revocability and reusability properties of key-based systems and exposes a subtle design trade-off between reducing information leakage from compromised systems and preventing successful attacks on systems whose data have not been compromised.","Title: Variable-length channel coding with noisy feedback\nYear: 2008\n\nAbstract: It is known that perfect noiseless feedback can be used to improve the reliability of communication systems. We show how to make those gains robust to noise on the feedback link. We focus on feedback links that are themselves discrete memoryless channels. We demonstrate that Forney's erasure-decoding exponent is achievable given any positive-capacity feedback channel. We also demonstrate that as the desired rate of communication approaches the capacity of the forward channel, the Burnashev upper bound on the reliability function is achievable given any positive-capacity noisy feedback channel. Finally, we demonstrate that our scheme dominates the erasure-decoding exponent at all rates and, for instance, at zero rate can achieve up to three-quarters of Burnashev's zero-rate reliability. This implies that in a shared medium, to maximise the reliability function some degrees of freedom should be allocated to feedback. Copyright (C) 2008 John Wiley & Sons, Ltd.","Title: Low-voltage on-chip cache architecture using heterogeneous cell sizes for high-performance processors\nYear: 2011\n\nAbstract: To date dynamic voltage/frequency scaling (DVFS) has been one of the most successful power-reduction techniques. However, ever-increasing process variability reduces the reliability of static random access memory (SRAM) at low voltages. This limits voltage scaling to a minimum operating voltage (VDDMIN). Larger SRAM cells, that are less sensitive to process variability, allow the use of lower VDDMIN. However, large-scale memory structures, e.g., the last-level cache (LLC) (that often determines the VDDMIN of the processor), cannot afford to use such large SRAM cells due to the die area constraint. In this paper we propose low-voltage LLC architectures that exploit 1) the DVFS characteristics of workloads running on high-performance processors, 2) the trade-off between SRAM cell size and VDDMIN, and 3) the fact that at lower voltage/frequency operating states the negative performance impact of having a smaller LLC capacity is reduced. Our proposed LLC architectures provide the same maximum performance and VDDMIN as the conventional architecture, while reducing the total LLC cell area by 15%--19% with negligible average runtime increase.","Title: Impact of channel sparsity and correlated eavesdropping on secret key generation from multipath channel randomness\nYear: 2010\n\nAbstract: We study secret key generation from reciprocal multipath wireless channels modeled as multiple parallel fading channels. We consider two channel characteristics that heavily impact secret key capacity: channel sparsity and correlation between main and eavesdropper's channels. We propose a joint model to capture the channel sparsity and correlated eavesdropping. For the case without eavesdroppers, we show that at each transmitter SNR γ there is an optimal sparsity 0 ≤ ρopt ≤ 1, which specifies the fraction of non-zero channel coefficients, that yields the maximum secret key capacity. The reduction in secret key capacity due to eavesdropping is due to two sources. First is the overlap between the main and eavesdropper channels, i.e., the pattern of non-zero subchannels common to both. The second is the correlation between the channel coefficients of the overlapping channels. We show that when the power of the training signal is uniformly distributed over the non-zero channels, there is a cutoff SNR γc below which the secret key rate is zero, but non-zero (and increasing in γ) when γ > γc. We also show that in the low SNR regime, the optimal input signal is peaky (a non-uniform training signal) by which the secret key capacity is non-zero at all γ > 0.","Title: Noisy feedback improves communication reliability\nYear: 2006\n\nAbstract: We show how to exploit a noisy feedback link to implement high-reliability communication. We specify a variable-length coding strategy that achieves the error exponent (in delay) of erasure decoding using any noisy feedback channel which has a positive zero-rate random coding error exponent. Building on this result, we give a second approach that, depending only on the capacity of the feedback link, achieves an error exponent up to half of the Burnashev exponent—the maximum exponent that can be achieved with a noiseless feedback link. The resulting exponent can be far larger than the exponent of erasure decoding, particularly at rates close to capacity. I. I NTRODUCTION Feedback is present in many deployed communication systems and yet the theory of feedback has made little impact on communications in practice. In part this is be- cause the models of instantaneous and noiseless feedback often assumed in theory do not match the delayed and noisy feedback usually available in practice. In this paper we look at one of the promised benefits of feedback— large increases in the reliability of communications over discrete memoryless channels (DMCs). We show that, to some degree, this benefit can still be realized even when the feedback link is itself a noisy channel. Essentially feedback makes it possible to increase the reliability of communication over a DMC because it enables the use of variable-length transmission. If the system detects that the channel noise has been atypically bad for the duration of transmission, it refrains from decoding until the channel appears to have improved. In contrast, in systems without feedback the duration of transmission must be fixed. Even if the channel noise is bad for the entire duration, the decoder has no option but to decode. We compare coding strategies based on their reliability functions (or error exponents), calculated in terms of the expected decoding delay. This is the length of time from when the source begins transmitting a message to when the destination makes a final decision. This function is logPr(error)/E (t).","Title: Analyzing the impact of joint optimization of cell size, redundancy, and ECC on low-voltage SRAM array total area\nYear: 2012\n\nAbstract: The increasing power consumption of processors has made power reduction a first-order priority in processor design. Voltage scaling is one of the most powerful power-reduction techniques introduced to date, but is limited to some minimum voltage VDDMIN. Below VDDMIN on-chip SRAM cells cannot all operate reliably due to increased process variability with technology scaling. The use of larger SRAM cells, which are less sensitive to process variability, allows a reduction in VDDMIN. However, since the large-scale memory structures such as last-level caches (LLCs) often determine the VDDMIN of processors, these structures cannot afford to use large SRAM cells due to the resulting increase in die area. In this paper we first propose a joint optimization of LLC cell size, the number of redundant cells, and the strength of error-correction coding (ECC) to minimize total SRAM area while meeting yield and targets. The joint use of redundant cells and ECC enables the use of smaller cell sizes while maintaining design targets. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. In 32-nm technology our joint approach yields a 27% reduction in total SRAM area (including the extra cells) when targeting 90% yield and 600 mV VDDMIN. Second, we demonstrate that the ECC used to repair defective cells can be combined with a simple architectural technique, which can also fix particle-induced soft errors, without increasing ECC strength or processor runtime.","Title: Cooperative Routing for Wireless Networks using Mutual-Information Accumulation\nYear: 2009\n\nAbstract: Cooperation between the nodes of wireless multihop networks can increase\ncommunication reliability, reduce energy consumption, and decrease latency. The\npossible improvements are even greater when nodes perform mutual information\naccumulation using rateless codes. In this paper, we investigate routing\nproblems in such networks. Given a network, a source, and a destination, our\nobjective is to minimize end-to-end transmission delay under energy and\nbandwidth constraints. We provide an algorithm that determines which nodes\nshould participate in forwarding the message and what resources (time, energy,\nbandwidth) should be allocated to each.\n Our approach factors into two sub-problems, each of which can be solved\nefficiently. For any transmission order we show that solving for the optimum\nresource allocation can be formulated as a linear programming problem. We then\nshow that the transmission order can be improved systematically by swapping\nnodes based on the solution of the linear program. Solving a sequence of linear\nprograms leads to a locally optimal solution in a very efficient manner. In\ncomparison to the proposed cooperative routing solution, it is observed that\nconventional shortest path multihop routing typically incurs additional delays\nand energy expenditures on the order of 70%.\n Our first algorithm is centralized, assuming that routing computations can be\ndone at a central processor with full access to channel state information for\nthe entire system. We also design two distributed routing algorithms that\nrequire only local channel state information. We provide simulations showing\nthat for the same networks the distributed algorithms find routes that are only\nabout two to five percent less efficient than the centralized algorithm.","Title: Exploiting Channel Diversity in Secret Key Generation From Multipath Fading Randomness\nYear: 2012\n\nAbstract: We design and analyze a method to extract secret keys from the randomness inherent to wireless channels. We study a channel model for a multipath wireless channel and exploit the channel diversity in generating secret key bits. We compare the key extraction methods based both on entire channel state information (CSI) and on single channel parameter such as the received signal strength indicators (RSSI). Due to the reduction in the degree-of-freedom when going from CSI to RSSI, the rate of key extraction based on CSI is far higher than that based on RSSI. This suggests that exploiting channel diversity and making CSI information available to higher layers would greatly benefit the secret key generation. We propose a key generation system based on low-density parity-check (LDPC) codes and describe the design and performance of two systems: one based on binary LDPC codes and the other (useful at higher signal-to-noise ratios) based on four-ary LDPC codes.","Title: Secret Key Generation from Sparse Wireless Channels: Ergodic Capacity and Secrecy Outage\nYear: 2013\n\nAbstract: This paper investigates generation of a secret key from a reciprocal wireless channel. In particular we consider wireless channels that exhibit sparse structure in the wideband regime and study the impact of sparsity on the secret key capacity. We explore this problem in two steps. First, we study key generation from a state-dependent discrete memoryless multiple source. The state of the source captures the effect of channel sparsity. Secondly, we consider a wireless channel model that captures channel sparsity and correlation between the legitimate users' channel and the eavesdropper's channel. Such dependency can significantly reduce the secret key capacity. According to system delay requirements, two performance measures are considered: (i) ergodic secret key capacity and (ii) outage probability. We show that in the wideband regime when a white sounding sequence is adopted, a sparser channel can achieve a higher ergodic secret key rate than a richer channel can. For outage performance, we show that if the users generate secret keys at a fraction of the ergodic capacity, the outage probability will decay exponentially in signal bandwidth. Moreover, a larger exponent is achieved by a richer channel.","Title: Lossless Coding For Distributed Streaming Sources\nYear: 2006\n\nAbstract: Distributed source coding is traditionally viewed in a block coding context wherein all source symbols are known in advance by the encoders. However, many modern applications to which distributed source coding ideas are applied, are better modeled as having streaming data. In a streaming setting, source symbol pairs are revealed to separate encoders in real time and need to be reconstructed at the decoder with subject to some tolerable end-to-end delay. In this paper, a causal sequential random binning encoder is introduced and paired with maximum likelihood (ML) and universal decoders. The latter uses a novel weighted empirical suffix entropy decoding rule. We derive a lower bounds on the error exponent with delay for each decoder. We also provide upper bounds for the special case of streaming with decoder side information and discuss when upper and lower bounds match. We show that both ML and universal decoders achieve the same (positive) error exponents for all rate pairs inside the Slepian-Wolf achievable rate region. The dominant error events in streaming are different from those in block-coding and result in different exponents. Because the sequential random binning scheme is also universal over delays, the resulting code eventually reconstructs every source symbol correctly with probability one.","Title: SleepScale: runtime joint speed scaling and sleep states management for power efficient data centers\nYear: 2014\n\nAbstract: Power consumption in data centers has been growing significantly in recent years. To reduce power, servers are beingequipped with increasingly sophisticated power management mechanisms. Different mechanisms offer dramatically different trade-offs between power savings and performance penalties. Considering the complexity, variety, and temporallyvarying nature of the applications hosted in a typical data center, intelligently determining which power management policy to use and when is a complicated task.\n\nIn this paper we analyze a system model featuring both performance scaling and low-power states. We reveal the interplay between performance scaling and low-power states via intensive simulation and analytic verification. Based on the observations, we present SleepScale, a runtime power management tool designed to efficiently exploit existing power control mechanisms. At run time, SleepScale characterizes power consumption and quality-of-service (QoS) for each lowpower state and frequency setting, and selects the best policy for a given QoS constraint. We evaluate SleepScale using workload traces from data centers and achieve significant power savings relative to conventional power management strategies","Title: Key Generation Using External Source Excitation: Capacity, Reliability, and Secrecy Exponent\nYear: 2012\n\nAbstract: We study the fundamental limits to secret key generation from an excited distributed source (EDS). In an EDS, a pair of terminals observe dependent sources of randomness excited by a pre-arranged signal. We first determine the secret key capacity for such systems with one-way public messaging. We then characterize a tradeoff between the secret key rate and exponential bounds on the probability of key agreement failure and on the secrecy of the key generated. We find that there is a fundamental tradeoff between reliability and secrecy.","Title: The sender-excited secret key agreement model: Capacity theorems\nYear: 2011\n\nAbstract: We consider the fundamental limits of the secret key generation problem when the sources are excited by the sender. In many practical communication settings, the channel may be influenced by the parties involved. Similar to recent works on probing capacity and channels with action-dependent states, our system model captures such a scenario. We derive single-letter expressions for the secret key capacity. Our coding strategy involves wiretap channel coding and a key generation scheme. By assuming that the eavesdropper receives a degraded version of the legitimate receiver's observation, we also obtain a capacity result that does not involve any auxiliary random variables. Finally, by studying two examples, we show that there is a fundamental tradeoff in between the amount of common randomness (i.e., the secret key rate) and the wiretap secrecy rate.","Title: Routing In Cooperative Wireless Networks With Mutual-Information Accumulation\nYear: 2008\n\nAbstract: Cooperation between the nodes of wireless multi-hop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investigate routing problems in such networks. Given a network, a source and a destination, our objective is to minimize end-to-end transmission delay under a sum energy constraint. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any node decoding order we show that solving for the optimum resource allocation can be formulated as a linear problem. We then show that the decoding order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear program leads to a locally optimum solution in a very efficient manner. In comparison to the cooperative routings, it is observed that conventional shortest-path multihop routings incur additional delays and energy expenditures on the order of 70%. Since this initial solution is centralized, requiring full channel state information, we exploit the insights to design two distributed routing algorithms that require only local channel state information. We provide simulations showing that in the same networks the distributed algorithms find routes that are only about 2 - 5% less efficient than the centralized solution.","Title: Passive learning of the interference graph of a wireless network\nYear: 2012\n\nAbstract: A key challenge in wireless networking is the management of interference between transmissions. Identifying which transmitters interfere with each other is crucial. Complicating this task is the fact that the topology of wireless networks can change from time to time, and so the identification process may need to be carried out on a regular basis. Injecting active probing traffic to assess interference can lead to unacceptable overhead, and so this paper focuses on interference estimation based on passive traffic monitoring in networks that use the CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) protocol. A graph is used to represent the interference in the network, where the nodes represent transmitters and edges represent interference between pairs of transmitters. We investigate the problem of learning the graph structure based on passive observations of network traffic transmission patterns and information about successes or failures in transmissions. Previous work has focused on algorithms and validations in small testbed networks. This paper focuses on the scaling behavior of such methods which is unaddressed in prior work. In particular we establish bounds on the minimum observation period required to identify the interference graph reliably. The main results are expressed in terms of the total number of nodes n and the maximum number of interfering transmitters per node (i.e., maximum node degree) d. The effects of hidden terminal interference (i.e., interference not detectable via carrier sensing) on the observation time requirement are also quantified. We show that it is necessary and sufficient that the observation period grows like d2 log n, and we propose a practical algorithm that reliably identifies the graph from this length of observation. We conclude that the observation requirements scale quite mildly with network size, and that the networks with sparse interference patterns can be more rapidly identified than those with de- se interference patterns.","Title: Minimum energy per bit for secret key acquisition over multipath wireless channels\nYear: 2009\n\nAbstract: We study fundamental limits on the generation of secret keys based on the randomness inherent to reciprocal wireless multipath channels. Estimates of the common channel at the two ends of a link are jointly Gaussian sources from which secret keys can be generated. The key generation problem is cast as an equivalent communication problem to characterize the secret key capacity. We analyze the low-SNR regime to quantify the minimum energy per secret key bit required for reliable key acquisition. Our results show that, in contrast to the low SNR behavior of conventional channel capacity, there is a non-zero SNR γ* that achieves the minimum energy per key bit. A time-sharing scheme is proposed to achieve the minimum energy per key bit at any SNR below γ*. We also investigate the reliability of secret key generation via error exponent analysis. In particular, our results yield a tight upper bound on the minimum energy required to generate a finite-length key with a specified probability of error in key acquisition.","Title: An information-theoretic analysis of revocability and reusability in secure biometrics\nYear: 2011\n\nAbstract: Secure biometric systems are designed to allow authentication without requiring a reference biometric sample to be stored in the clear at the access control device. Instead, a template extracted from the reference biometric is stored on the device. An enrolled user can be authenticated by the template combined with a legitimate test biometric. However, an attacker who infiltrates the device only discovers the template, which reveals little or no information about the true biometric. We present a general framework for secure biometric authentication systems, and then provide a comparative information-theoretic analysis of two related realizations: (1) fuzzy commitment, in which authentication is framed as a problem of correcting errors between the reference and test biometrics, and (2) secure sketches, in which authentication is framed as a Slepian-Wolf decoding problem. We derive the false reject rates, false accept rates and successful attack rates for both realizations. We also consider the information leaked about a user's biometric identity when the database of biometric templates is compromised. Finally, we analyze a scenario in which the same biometric has been used to generate templates for several access control devices, some of which have been compromised by an adversary. It is shown that, two-factor versions of fuzzy commitment and secure sketch not only allow revocability, but also provide resistance to attacks in which the adversary compromises several databases at the same time.","Title: Optimal Backpressure Scheduling in Wireless Networks using Mutual Information Accumulation\nYear: 2011\n\nAbstract: In this paper we develop scheduling policies that maximize the stability region of a wireless network under the assumption that mutual information accumulation is implemented at the physical layer. When the link quality between nodes is not sufficiently high that a packet can be decoded within a single slot, the system can accumulate information across multiple slots, eventually decoding the packet. The result is an expanded stability region. The accumulation process over weak links is temporally coupled and therefore does not satisfy the independent and identically distributed (i.i.d) assumption that underlies many previous analysis in this area. Therefore the problem setting also poses new analytic challenges. We propose two dynamic scheduling algorithms to cope with the non-i.i.d nature of the decoding. The first performs scheduling every $T$ slots, and approaches the boundary of the stability region as $T$ gets large, but at the cost of increased average delay. The second introduces virtual queues for each link and constructs a virtual system wherein two virtual nodes are introduced for each link. The constructed virtual system is shown to have the same stability region as the original system. Through controlling the virtual queues in the constructed system, we avoid the non-i.i.d analysis difficulty and attain the full stability region. We derive performance bounds for both algorithms and compare them through simulation results.","Title: The Sender-Excited Secret Key Agreement Model: Capacity, Reliability, and Secrecy Exponents\nYear: 2015\n\nAbstract: We consider the secret key generation problem when sources are randomly excited by the sender and there is a noiseless public discussion channel. Our setting is thus similar to recent works on channels with action-dependent states, where the channel state may be influenced by some of the parties involved. We derive single-letter expressions for the secret key capacity through a type of source emulation analysis. We also derive lower bounds on the achievable reliability and secrecy exponents, i.e., the exponential rates of decay of the probability of decoding error and of the information leakage. These exponents allow us to determine a set of strongly achievable secret key rates. For degraded eavesdroppers, the maximum strongly achievable rate equals the secret key capacity; our exponents can also be specialized to previously known results. In deriving our strong achievability results, we introduce a coding scheme that combines wiretap coding (to excite the channel) and key extraction (to distill keys from residual randomness). The secret key capacity is naturally seen to be a combination of both source- and channel-type randomness. Through examples, we illustrate a fundamental interplay between the portion of the secret key rate due to each type of randomness. We also illustrate inherent tradeoffs between the achievable reliability and secrecy exponents. Our new scheme also naturally accommodates rate limits on the public discussion. We show that under rate constraints, we are able to achieve larger rates than those that can be attained through a pure source emulation strategy.","Title: The ADMM penalized decoder for LDPC codes.\nYear: 2014\n\nAbstract: Linear programming (LP) decoding for low-density parity-check codes was introduced by Feldman et al. and has been shown to have theoretical guarantees in several regimes. Furthermore, it has been reported in the literature-via simulation and via instanton analysis-that LP decoding displays better error rate performance at high signal-to-noise ratios (SNR) than does belief propagation (BP) decoding...","Title: LP-decodable multipermutation codes\nYear: 2014\n\nAbstract: In this paper, we introduce a new way of constructing and decoding multipermutation codes. Multipermutations are permutations of a multiset that may consist of duplicate entries. We first introduce a new class of matrices called multipermutation matrices. We characterize the convex hull of multipermutation matrices. Based on this characterization, we propose a new class of codes that we term LP-decodable multipermutation codes. Then, we derive two LP decoding algorithms. We first formulate an LP decoding problem for memoryless channels. We then derive an LP algorithm that minimizes the Chebyshev distance. Finally, we show a numerical example of our algorithm.","Title: Suppressing pseudocodewords by penalizing the objective of LP decoding\nYear: 2012\n\nAbstract: In this paper, we present a new class of decoders for low density parity check (LDPC) codes. We are motivated by the observation that the linear programming (LP) decoder has worse error performance than belief propagation (BP) decoders at low SNRs. We base our new decoders on the alternating direction method of multipliers (ADMM) decomposition technique for LP decoding. The ADMM not only efficiently solves the LP decoding problem, but also makes it possible to explore other decoding algorithms. In particular, we add various penalty terms to the linear objective of LP decoding with the goal of suppressing pseudocodewords. Simulation results show that the new decoders achieve much better error performance compared to LP decoder at low SNRs. What is more, similar to the LP decoder, no error floor is observed at high SNRs.","Title: Instanton search algorithm for the ADMM penalized decoder\nYear: 2014\n\nAbstract: Linear programming (LP) decoding using the alternating direction method of multipliers (ADMM) has been shown to be an efficient algorithm. A non-convex variation based on the ADMM LP decoder called the ADMM penalized decoder was introduced by Liu et al. (IEEE ITW, Sep. 2012) to close the signal-to-noise ratio (SNR) gap between LP decoding and classic belief propagation (BP) decoding. This algorithm was shown to achieve or outperform BP decoding at all SNRs, including high SNRs where BP decoding suffers from the error floor effect. In this paper, we study the behaviors of the ADMM penalized decoder at high SNRs where simulation is infeasible. We use a generic tool called instanton analysis and propose an instanton search algorithm for the ADMM penalized decoder. We then apply the algorithm to the [155, 64] Tanner code and a [1057, 813] LDPC code. We show that the instanton information we obtained provides good predictions for word-error-rate curve at high SNRs. In addition, our results suggest that the ADMM penalized decoder can suffer from trapping sets.","Title: ADMM decoding of non-binary LDPC codes in F2m\nYear: 2014\n\nAbstract: In this paper, we develop an efficient algorithm for linear programming (LP) decoding of non-binary low-density parity-check (LDPC) codes. We build our algorithm on the decomposition method based on the alternating direction method of multipliers (ADMM). Although expressing the LP decoding problem using ADMM is not hard, a sub-routine of ADMM - projection onto a polytope formed from embeddings of the non-binary single parity-check code - is not straightforward. In this work, we focus on non-binary codes in fields of characteristic two. This allows us to use operations in F2 to relax the polytope under consideration into a form that is computational friendly. We introduce a rotation step that normalizes the geometry under consideration. We then apply ADMM a second time to solve the projection problem, which is a quadratic program (QP). Our decoding algorithm scales linearly with block length, linearly with check degree, and quadratically with field size.","Title: Achievability bounds for unequal message protection at finite block lengths\nYear: 2014\n\nAbstract: We study achievability bounds for a class of unequal error protection codebooks with m > 1 different classes of codewords called unequal message protection (UMP) codes. We extend the dependence testing bound due to Polyanskiy-Poor-Verdú to be applicable to UMP codes and use this extension to obtain refined asymptotic expansions for the performance of such codes over discrete memoryless channels. In addition, we consider two questions related to the practical construction of UMP codes. First, we study a “header” construction that prefixes the message class into a header followed by data protection using a standard homogeneous (classical) code. We show that, in general, this construction is not optimal at finite block lengths. We further demonstrate that our main UMP achievability bound can be obtained using coset codes, which suggests a path to tractable implementation of UMP codes.","Title: The Streaming-DMT of Fading Channels\nYear: 2014\n\nAbstract: We consider the sequential transmission of a stream of messages over a block-fading multi-input-multi-output channel. A new message arrives at the beginning of each coherence block, and the decoder is required to output each message sequentially, after a delay of T coherence blocks. In the special case when T = 1, the setup reduces to the quasi-static fading channel. We establish the optimal diversity-multiplexing tradeoff (DMT) in the high signal-to-noise-ratio (SNR) regime, and show that it equals T times the DMT of the quasi-static channel. The converse is based on utilizing the delay constraint to amplify a local outage event associated with a message, globally across all the coherence blocks. This approach appears to be new. We propose two coding schemes that achieve the optimal DMT. The first scheme involves interleaving of messages, such that each message is transmitted across T consecutive coherence blocks. This scheme requires the knowledge of the delay constraint at both the encoder and decoder. Our second coding scheme involves a sequential tree code and is delay universal, i.e., the knowledge of the decoding delay is not required by the encoder. However, in this scheme, we require the coherence block length to increase as log (SNR), in order to attain the optimal DMT. Finally, we discuss the case when multiple messages arrive at uniform intervals within each coherence period. Through a simple example, we exhibit the suboptimality of interleaving and propose another scheme that achieves the optimal DMT.","Title: On mismatched unequal message protection for finite block length joint source-channel coding\nYear: 2014\n\nAbstract: We study the problem of lossless joint source-channel coding (JSCC) in the finite block length regime from an unequal message protection (UMP) perspective. We demonstrate that the problem of lossless JSCC can be cast in terms of UMP codes previously studied. We show that an optimal JSCC can be constructed from a matched UMP code. We further derive a finite block length bound that characterizes the performance of a JSCC constructed from a UMP code not perfectly matched to the source. This bound is evaluated for a binary memoryless source transmitted over a binary symmetric channel. Two-class schemes previously studied in literature are compared with the proposed scheme. Empirically the JSCCs based on UMP codes approach the performance of the optimal matched code quite fast in number of classes used.","Title: A universal approach to queuing with distortion control\nYear: 2005\n\nAbstract: An efficient buffer-management algorithm is developed for queues that handle distortion-tolerant data under finite memory limitations. We avoid overflows and realize significant performance gains through the use of multiresolution source codes. These codes enable us to reduce the fidelity of signal descriptions in a controlled progressive manner. The proposed approach is universal, i.e., it works without knowledge of queue arrival and departure statistics. More strongly, we show that its performance is sample-path optimal, i.e., it achieves an average distortion equal to the best achievable by any algorithm, including those designed with full noncausal knowledge of queue arrival and service times.","Title: Boosting reliability over AWGN networks with average power constraints and noiseless feedback\nYear: 2005\n\nAbstract: For the point-to-point additive white Gaussian noise (AWGN) channel with noiseless feedback and an average power constraint, Schalkwijk and Kailath's scheme achieves a doubly- exponential decay of the probability of error. While some coding schemes for networks with noiseless feedback incorporate variations on the Schalkwijk-Kailath scheme, they do not in general achieve better than single-exponential decays in their probabilities of error everywhere in their achievable rate regions. We give a technique that can boost the reliability as high as desired of any from a large class of block coding schemes for networks with feedback. The technique relies crucially on the average nature of the power constraints. We explain and illustrate our results in the context of Ozarow's feedback strategy for the AWGN multiple-access channel. I. I NTRODUCTION For the point-to-point AWGN channel with an average power constraint, Shannon (1) shows that feedback does not increase capacity. That noiseless feedback of the channel out- put is nevertheless useful for AWGN channels is shown, e.g., by Schalkwijk and Kailath (2), where they construct a simple code that achieves a doubly-exponential decay of the error probability with increasing block-length. Later, Kramer (8) analyzed a different model in which such noiseless output feedback is replaced by noiseless decision feedback, i.e., exact knowledge of what decision the decoder is about to make. Even with this weaker model, Kramer is able to show faster than doubly-exponential decay of the error probability. For AWGN networks, the situation is different in two respects. First, feedback does increase the achievable rates in many cases. Second, network reliability functions (error exponents) without feedback are mostly unknown. Indeed, many existing coding theorems for AWGN networks with feedback and average power constraints do not yield spectac- ular error exponents. Whenever typicality arguments are used, the dependence of the error probability on the block-length N becomes obscured. While there is usually an exponential term that comes from the difference of the rate and the relevant mutual information expression, there is also an term that covers the probability of the atypical set. Given the nature of the AWGN channel, in most cases we can apply a Chernoff bound and see that is also an exponentially small function of the block length. However, the exponent involved can be quite low. The situation is best illustrated by the AWGN multiple- access channel (MAC) with noiseless output feedback. Ozarow determines the full capacity region in (5), as illus-","Title: Sequential random binning for streaming distributed source coding\nYear: 2005\n\nAbstract: Random binning arguments underlie many results in information theory. In this paper we introduce and analyze a novel type of causal random binning - \"sequential\" binning. This binning is used to get stream- ing Slepian-Wolf codes with an \"anytime\" character. At the decoder, the probability of estimation error on any particular symbol goes to zero exponentially fast with delay. In the non-distributed context, we show equivalent results for fixed-rate streaming entropy coding. Because of space constraints, we present full derivations only for the latter, stating the results for the distributed problem. We give bounds on error exponents for both universal and maximum-likelihood decoders. I. I NTRODUCTION","Title: Compound conditional source coding, Slepian-Wolf list decoding, and applications to media coding\nYear: 2007\n\nAbstract: We introduce a novel source coding problem, compound conditional source coding. We describe how a number of media coding problems can be cast into this framework. We develop the achievable rate region for this problem and error exponent results. We show that the reliability function of compound conditional source coding is at least as large as the list-decoding error exponent of Slepian-Wolf coding, which we develop in addition. A message of the paper is that a number of media coding scenarios where distributed source coding techniques are being used are more exactly stated as compound conditional problems. This insight can lead to improved system performance, as we demonstrate for error exponents. IEEE International Symposium on Information Theory (ISIT)","Title: The “hallucination” bound for the BSC\nYear: 2008\n\nAbstract: Though the schemes are different, both Horstein's and Kudryashov's non-block strategies for communication with feedback over the binary-symmetric channel asymptotically achieve the identical reliability function (error exponent); a function that displays some curious features. For positive rates it is strictly larger than Burnashev's reliability function and transitions discontinuously at the channel capacity from a strictly positive value to zero. The purpose of this paper is to connect this reliability function to familiar coding contexts and to demonstrate that it provides an upper bound on the error exponents achievable in these contexts. We first show that this function gives a lower bound on the minimum probability of decoding error across codewords in a block-coding context with (or without) feedback. We then show that the same reliability function also gives an upper bound on the maximum probability of bit error in a non-block \"streaming\" context where noiseless feedback is available and the destination is (occasionally) allowed to declare erasures (per Forney). The basic insight underlying the bound leads to the moniker the \"hallucination\" bound.","Title: Streaming data over fading wireless channels: The diversity-multiplexing tradeoff\nYear: 2011\n\nAbstract: We study delay constrained sequential streaming over block fading channels. The transmitter observes a stream of messages, one message in each coherence block, and the receiver needs to output a sequence of messages, each with a fixed delay of T coherence blocks. We characterize the associated diversity-multiplexing tradeoff (DMT) for this model. The proposed coding scheme involves a semi-infinite random Gaussian tree-code and a sequential decision directed decoder. The converse applies an outage amplification argument that exploits the delay constraint to amplify the error event associated with a single message to an entire sequence of messages.","Title: Rank minimization over finite fields\nYear: 2011\n\nAbstract: This paper establishes information-theoretic limits in estimating a finite field low-rank matrix given random linear measurements of it. Necessary and sufficient conditions on the number of measurements required are provided. It is shown that these conditions are sharp. The reliability function associated to the minimum-rank decoder is also derived. Our bounds hold even in the case where the sensing matrices are sparse. Connections to rank-metric codes are discussed.","Title: Rank Minimization Over Finite Fields: Fundamental Limits and Coding-Theoretic Interpretations\nYear: 2012\n\nAbstract: This paper establishes information-theoretic limits for estimating a finite-field low-rank matrix given random linear measurements of it. These linear measurements are obtained by taking inner products of the low-rank matrix with random sensing matrices. Necessary and sufficient conditions on the number of measurements required are provided. It is shown that these conditions are sharp and the minimum-rank decoder is asymptotically optimal. The reliability function of this decoder is also derived by appealing to de Caen's lower bound on the probability of a union. The sufficient condition also holds when the sensing matrices are sparse—a scenario that may be amenable to efficient decoding. More precisely, it is shown that if the $n\\\\times n$-sensing matrices contain, on average, $\\\\Omega ({n}{\\\\log n})$ entries, the number of measurements required is the same as that when the sensing matrices are dense and contain entries drawn uniformly at random from the field. Analogies are drawn between the aforementioned results and rank-metric codes in the coding theory literature. In fact, we are also strongly motivated by understanding when minimum rank distance decoding of random rank-metric codes succeeds. To this end, we derive minimum distance properties of equiprobable and sparse rank-metric codes. These distance properties provide a precise geometric interpretation of the fact that the sparse ensemble requires as few measurements as the dense one.","Title: Rateless Coding for Arbitrary Channel Mixtures With Decoder Channel State Information\nYear: 2009\n\nAbstract: Rateless coding has recently been the focus of much practical as well as theoretical research. In this paper, rateless codes are shown to find a natural application in channels where the channel law varies unpredictably. Such unpredictability means that to ensure reliable communication block codes are limited by worst case channel variations. However, the dynamic decoding nature of rateless codes allows them to adapt opportunistically to channel variations. If the channel state selector is not malicious, but also not predictable, decoding can occur earlier, producing a rate of communication that can be much higher than the worst case. The application of rateless or ldquofountainrdquo codes to the binary erasure channel (BEC) can be understood as an application of these ideas. Further, this sort of decoding can be usefully understood as an incremental form of erasure decoding. The use of ideas of erasure decoding result in a significant increase in reliability.","Title: Decomposition Methods for Large Scale LP Decoding\nYear: 2012\n\nAbstract: When binary linear error-correcting codes are used over symmetric channels, a relaxed version of the maximum likelihood decoding problem can be stated as a linear program (LP). This LP decoder can be used to decode error-correcting codes at bit-error-rates comparable to state-of-the-art belief propagation (BP) decoders, but with significantly stronger theoretical guarantees. However, LP decoding when implemented with standard LP solvers does not easily scale to the block lengths of modern error correcting codes. In this paper, we draw on decomposition methods from optimization theory, specifically the alternating direction method of multipliers (ADMM), to develop efficient distributed algorithms for LP decoding. The key enabling technical result is a “two-slice” characterization of the parity polytope, the polytope formed by taking the convex hull of all codewords of the single parity check code. This new characterization simplifies the representation of points in the polytope. Using this simplification, we develop an efficient algorithm for Euclidean norm projection onto the parity polytope. This projection is required by the ADMM decoder and its solution allows us to use LP decoding, with all its theoretical guarantees, to decode large-scale error correcting codes efficiently. We present numerical results for LDPC codes of lengths more than 1000. The waterfall region of LP decoding is seen to initiate at a slightly higher SNR than for sum-product BP, however an error floor is not observed for LP decoding, which is not the case for BP. Our implementation of LP decoding using the ADMM executes as fast as our baseline sum-product BP decoder, is fully parallelizable, and can be seen to implement a type of message-passing with a particularly simple schedule.","Title: Converse bounds for assorted codes in the finite blocklength regime\nYear: 2013\n\nAbstract: We study converse bounds for unequal error protection codebooks with k > 1 different classes of codewords. We dub these unequal error protection codes “assorted codes”. We extend a finite blocklength converse bound due to Polyanskiy-Poor-Verdú to apply to assorted codes and use this extension to obtain a refined asymptotic expansion for the performance of assorted codes over a discrete memoryless channel. Our main contribution is to demonstrate that there is indeed a loss in the rates of an assorted code compared to equivalent homogeneous (classical) codes. Notably, when the number of codeword classes is polynomial in blocklength n the loss is apparent in the third order O(log n) term of the asymptotic expansion of the logarithm of the maximum number of codewords. This is in sharp contrast to the previous literature which only considers this problem within regimes where no such loss could be observed.","Title: Lossless Coding for Distributed Streaming Sources\nYear: 2014\n\nAbstract: Distributed source coding is traditionally viewed in a block coding context wherein all source symbols are known in advance by the encoders. However, many modern applications to which distributed source coding ideas are applied, are better modeled as having streaming data. In a streaming setting, source symbol pairs are revealed to separate encoders in real time and need to be reconstructed at the decoder with subject to some tolerable end-to-end delay. In this paper, a causal sequential random binning encoder is introduced and paired with maximum likelihood (ML) and universal decoders. The latter uses a novel weighted empirical suffix entropy decoding rule. We derive a lower bounds on the error exponent with delay for each decoder. We also provide upper bounds for the special case of streaming with decoder side information and discuss when upper and lower bounds match. We show that both ML and universal decoders achieve the same (positive) error exponents for all rate pairs inside the Slepian-Wolf achievable rate region. The dominant error events in streaming are different from those in block-coding and result in different exponents. Because the sequential random binning scheme is also universal over delays, the resulting code eventually reconstructs every source symbol correctly with probability one.","Title: On blind compression of encrypted data approaching the source entropy rate\nYear: 2005\n\nAbstract: Traditional data transmission over an insecure noiseless channel consists of rst compressing data for eciency and then encrypting it for security. Reversing the order of these operations is considered in Johnson et al. (6). The central realization is that while the raw and encrypted data are sta- tistically independent, the encrypted data and key sequence are not. If distributed source coding techniques are used to compress and to jointly decode and decrypt the data, re- versing the order need not lead to performance reductions in either communication eciency or security. In this pa- per, we build on this work by considering systems that must operate without knowledge of the underlying source statis- tics. We present and analyze an incremental scheme based on exponentially increasing block lengths that is designed to balance the resolution rate of parameter estimation with the redundancy rate of communication. We show that the re- dundancy at best declines proportional to the inverse of the square root of the block length. We implement these ideas using low-density parity check (LDPC) codes. In practical tests to transmit a binary source of 100; 000 bits, ideally com- pressible to 17; 912 bits with perfect knowledge and an ideal code, required only 26; 787 bits. In comparison, to trans- mit this source with full knowledge of the source statistics required 21; 704 bits.","Title: The AWGN Red Alert Problem\nYear: 2011\n\nAbstract: Consider the following unequal error protection scenario. One special message, dubbed the “red alert” message, is required to have an extremely small probability of missed detection. The remainder of the messages must keep their average probability of error and probability of false alarm below a certain threshold. The goal then is to design a codebook that maximizes the error exponent of the red alert message while ensuring that the average probability of error and probability of false alarm go to zero as the blocklength goes to infinity. This red alert exponent has previously been characterized for discrete memoryless channels. This paper completely characterizes the optimal red alert exponent for additive white Gaussian noise channels with block power constraints.","Title: Cooperative reliability for streaming multiple access\nYear: 2010\n\nAbstract: In this paper we bound the reliability function of decoding with errors and erasures for a streaming multiple-access channel with feedback. We show that, subject to an arbitrarily small bound on the probability of erasure, the best known lower bound on the reliability function (i.e., achievable error exponent) for the single-user version of our problem can also be achieved in the multi-user setting for high sum-rates. In other words, at high rates the interference of another user need not decrease the achievable error exponent of either.","Title: Secure Biometrics: Concepts, Authentication Architectures, and Challenges\nYear: 2013\n\nAbstract: Biometrics are an important and widely used class of methods for identity verification and access control. Biometrics are attractive because they are inherent properties of an individual. They need not be remembered like passwords and are not easily lost or forged like identifying documents. At the same time, biometrics are fundamentally noisy and irreplaceable. There are always slight variations among the measurements of a given biometric, and, unlike passwords or identification numbers, biometrics are derived from physical characteristics that cannot easily be changed. The proliferation of biometric usage raises critical privacy and security concerns that, due to the noisy nature of biometrics, cannot be addressed using standard cryptographic methods. In this article, we present an overview of secure biometrics, also referred to as biometric template protection, an emerging class of methods that address these concerns.","Title: Proactive Message Passing on Memory Factor Networks.\nYear: 2016\n\nAbstract: We introduce a new type of graphical model that we call a \"memory factor network\" (MFN). We show how to use MFNs to model the structure inherent in many types of data sets. We also introduce an associated message-passing style algorithm called \"proactive message passing\"' (PMP) that performs inference on MFNs. PMP comes with convergence guarantees and is efficient in comparison to competing algorithms such as variants of belief propagation. We specialize MFNs and PMP to a number of distinct types of data (discrete, continuous, labelled) and inference problems (interpolation, hypothesis testing), provide examples, and discuss approaches for efficient implementation.","Title: Encoding and decoding algorithms for LP-decodable multipermutation codes\nYear: 2015\n\nAbstract: LP-decodable multipermutation codes are a class of multipermutation codes that can be decoded using linear programming (LP). These codes are defined using linearly constrained multipermutation matrices, which are binary matrices that satisfy particular row sum and column sum constraints. Although generic LP solvers are capable of solving the LP decoding problem, they are not efficient in general because they do not leverage structures of the problem. This motivates us to study efficient decoding algorithms. In this paper, we focus on encoding and decoding algorithms for LP-decodable multipermutation codes. We first describe an algorithm that “ranks” multipermutations. In other words, it maps consecutive integers, one by one, to an ordered list of multipermutations. By leveraging this algorithm, we develop an encoding algorithm for a code proposed by Shieh and Tsai. Regarding decoding algorithms we propose an iterative decoding algorithm based on the alternating direction method of multipliers (ADMM), each iteration of which can be solved efficiently using off-the-shelf techniques. Finally, we study decoding performances of different decoders via simulation.","Title: Feature transformation of biometric templates for secure biometric systems based on error correcting codes\nYear: 2008\n\nAbstract: Secure storage of biometric templates is extremely important because a compromised biometric cannot be revoked and replaced an unlimited number of times. In many approaches proposed for secure biometric storage, an error correcting code (ECC) is applied to the enrollment biometric and the resulting parity or syndrome symbols are stored on the access control device, instead of the original biometric. The principal challenge here is that most standard ECCs are designed for memoryless channel statistics, whereas the variations between enrollment and probe biometrics have significant spatial correlation. To address this challenge, we propose to transform the original biometric into a feature vector that is explicitly matched to standard ECCs, thereby improving the security-robustness tradeoff of the overall biometric system. As a concrete example, we transform fingerprint minutiae maps into feature vectors compatible with ECCs designed for a binary symmetric channel. We conduct a statistical analysis of these feature vectors and show how our feature transformation algorithm may be combined with Low-Density Parity Check (LDPC) codes to obtain a secure fingerprint biometric system.","Title: Hardware Based Projection Onto The Parity Polytope And Probability Simplex\nYear: 2016\n\nAbstract: This paper is concerned with the adaptation to hardware of methods for Euclidean norm projections onto the parity polytope and probability simplex. We first refine recent efforts to develop efficient methods of projection onto the parity polytope. Our resulting algorithm can be configured to have either average computational complexity O(d) or worst case complexity O(d log d) on a serial processor where d is the dimension of projection space. We show how to adapt our projection routine to hardware. Our projection method uses a sub-routine that involves another Euclidean projection; onto the probability simplex. We therefore explain how to adapt to hardware a well know simplex projection algorithm. The hardware implementations of both projection algorithms achieve area scalings of O(d (log d)(2)) at a delay of O((log d)(2)). Finally, we present numerical results in which we evaluate the fixed-point accuracy and resource scaling of these algorithms when targeting a modern FPGA.","Title: Hardware-Based ADMM-LP Decoding.\nYear: 2016\n\nAbstract: In this paper we present an FPGA-based implementation of linear programming (LP) decoding. LP decoding frames error correction as an optimization problem. This is in contrast to variants of belief propagation (BP) decoding that view error correction as a problem of graphical inference. There are many advantages to taking the optimization perspective: convergence guarantees, improved performance in certain regimes, and a methodology for incorporating the latest developments in optimization techniques. However, LP decoding, when implemented with standard LP solvers, does not easily scale to the blocklengths of modern error-correction codes. In earlier work, we showed that by drawing on decomposition methods from optimization theory, specifically the alternating direction method of multipliers (ADMM), we could build an LP decoding solver that was competitive with BP, both in terms of performance and speed. We also observed empirically that LP decoders have much better high-SNR performance in the \"error floor\" regime, a trait of particular relevance to optical transport and storage applications. While our previous implementation was in floating point, in this paper we report initial results of a fixed-point, hardware-based realization of our ADMM-LP decoder.","Title: Hardware-Based Linear Program Decoding with the Alternating Direction Method of Multipliers.\nYear: 2016\n\nAbstract: We present a hardware-based implementation of linear program (LP) decoding for binary linear codes. LP decoding frames error-correction as an optimization problem. In contrast, variants of belief propagation (BP) decoding frame error-correction as a problem of graphical inference. LP decoding has several advantages over BP-based methods, including convergence guarantees and better error-rate perfo...","Title: Anytime coding for distributed computation.\nYear: 2016\n\nAbstract: novel coding scheme is proposed to speed up distributed computation through a form of approximate computing. It is known that task replication can greatly mitigate the \"straggler effect\" in cloud computing, wherein an overall computation can be significantly delayed by slowed processing nodes (or \"stragglers\"). It has also been demonstrated that, in certain contexts, ideas of error-correction coding can more efficiently deal with stragglers than pure replication. The approach proposed herein builds on these earlier observations through an \"anytime\" approach to approximate computing. In this paradigm, over time one can produces approximate solutions of increasing accuracy. To accomplish this we first decompose a computational job in to tasks of various priorities. Next, we apply linear error correction coding to produce subtasks that are assigned to different processors. The decomposition used has a big effect on the type of anytime performance we attain. We study this scheme in a general framework in terms of the expected cost of the approximate solution. We further explore the approach in the context of vector-matrix multiplication. The proposed construction is numerically studied and, in comparison to previous work, demonstrates a significant improvement in the accuracy/latency trade-off.","Title: Bit-Interleaved Polar-Coded Ofdm For Low-Latency M2m Wireless Communications\nYear: 2017\n\nAbstract: Machine-to-machine (M2M) communications play an important role for applications that involve connections between a massive number of heterogeneous devices in home and industrial networks. For M2M networks, realizing low latency and high reliability is of great importance. In this paper, we show the great potential of polar-coded orthogonal frequency-division multiplexing (OFDM) to fulfill those requirements. We show that polar codes with list decoding plus cyclic redundancy check (CRC) can outperform state-of-the-art low-density parity-check (LDPC) codes at short block lengths. In addition, we introduce an efficient interleaver and constellation shaping for polar-coded high-order modulations, where a coded sequence is carefully mapped across subcarriers and modulation bits to exploit non-uniform reliability for higher diversity gains. Through computer simulations, we demonstrate that a significant gain greater than 2 dB can be achieved by quadratic polynomial permutation (QPP) interleaver with optimized parameters in comparison to the conventional random interleaver for high-order 256-ary quadrature-amplitude modulation (QAM) OFDM transmission in frequency-selective wireless channels.","Title: Fast Power and Energy Management for Future Many-Core Systems.\nYear: 2017\n\nAbstract: Future servers will incorporate many active low-power modes for each core and for the main memory subsystem. Though these modes provide flexibility for power and/or energy management via Dynamic Voltage and Frequency Scaling (DVFS), prior work has shown that they must be managed in a coordinated manner. This requirement creates a combinatorial space of possible power mode configurations. As a result, it becomes increasingly challenging to quickly select the configuration that optimizes for both performance and power/energy efficiency.\n\nIn this article, we propose a novel queuing model for working with the abundant active low-power modes in many-core systems. Based on the queuing model, we derive two fast algorithms that optimize for performance and efficiency using both CPU and memory DVFS. Our first algorithm, called FastCap, maximizes the performance of applications under a full-system power cap, while promoting fairness across applications. Our second algorithm, called FastEnergy, maximizes the full-system energy savings under predefined application performance loss bounds. Both FastCap and FastEnergy operate online and efficiently, using a small set of performance counters as input. To evaluate them, we simulate both algorithms for a many-core server running different types of workloads. Our results show that FastCap achieves better application performance and fairness than prior power capping techniques for the same power budget, whereas FastEnergy conserves more energy than prior energy management techniques for the same performance constraint. FastCap and FastEnergy together demonstrate the applicability of the queuing model for managing the abundant active low-power modes in many-core systems.","Title: Anytime Exploitation of Stragglers in Synchronous Stochastic Gradient Descent\nYear: 2017\n\nAbstract: In this paper we propose an approach to parallelizing synchronous stochastic gradient descent (SGD) that we term “Anytime-Gradients”. The Anytime-Gradients is designed to exploit the work completed by slow compute nodes or “stragglers”. In many approaches work completed by these nodes, while only partial, is discarded completely. To maintain synchronization in our approach, each computational epoch is of fixed duration, and at the end of each epoch, workers send updated parameter vectors to a master mode for combination. The master weights each update by the amount of work done. The Anytime-Gradients scheme is robust to both persistent and non-persistent stragglers and requires no prior knowledge about processor abilities. We show that the scheme effectively exploits stragglers and outperforms existing methods.","Title: Irregular Polar Coding for Massive MIMO Channels.\nYear: 2017\n\nAbstract: Recent advancements in polar coding have achieved practical performance competitive with other capacity-achieving codes such as low-density parity-check codes. In this paper, we propose a new family called irregular polar codes, where polarlization units are irregularly inactivated to achieve additional degrees of freedom for code design. We first discuss the code construction for irregular polar-coded modulation by taking non-uniform bit-reliability into consideration. We then apply the proposed polar codes to wireless massive multiple-input multiple-output (MIMO) communication channels. Simulation results show that the irregular polar codes can significantly reduce encoding/decoding complexity up to 50% while also yielding a marginal improvement in error rate performance.","Title: Exploitation Of Stragglers In Coded Computation\nYear: 2018\n\nAbstract: In cloud computing systems slow processing nodes, often referred to as \"stragglers\", can significantly extend the computation time. Recent results have shown that error correction coding can be used to reduce the effect of stragglers. In this work we introduce a scheme that, in addition to using error correction to distribute mixed jobs across nodes, is also able to exploit the work completed by all nodes, including stragglers. We first consider vector-matrix multiplication and apply maximum distance separable (MDS) codes to small blocks of sub-matrices. The worker nodes process blocks sequentially, working block-by-block, transmitting partial per-block results to the master as they are completed. Sub-blocking allows a more continuous completion process, which thereby allows us to exploit the work of a much broader spectrum of processors and reduces computation time. We then apply this technique to matrix-matrix multiplication using product code. In this case, we show that the order of computing sub-tasks is a new degree of design freedom that can be exploited to reduce computation time further. We propose a novel approach to analyze the finishing time, which is different from typical order statistics. Simulation results show that the expected computation time decreases by a factor of at least two in compared to previous methods.","Title: Hierarchical Coded Computation\nYear: 2018\n\nAbstract: Coded computation is a method to mitigate \"stragglers\" in distributed computing systems through the use of error correction coding that has lately received significant attention. First used in vector-matrix multiplication, the range of application was later extended to include matrix-matrix multiplication, heterogeneous networks, convolution, and approximate computing. A drawback to previous results is they completely ignore work completed by stragglers. While stragglers are slower compute nodes, in many settings the amount of work completed by stragglers can be non-negligible. Thus, in this work, we propose a hierarchical coded computation method that exploits the work completed by all compute nodes. We partition each node's computation into layers of sub-computations such that each layer can be treated as (distinct) erasure channel. We then design different erasure codes for each layer so that all layers have the same failure exponent. We propose design guidelines to optimize parameters of such codes. Numerical results show the proposed scheme has an improvement of a factor of 1.5 in the expected finishing time compared to previous work.","Title: Efficient learning of neighbor representations for boundary trees and forests.\nYear: 2018\n\nAbstract: We introduce a semiparametric approach to neighbor-based classification. We build off the recently proposed Boundary Trees algorithm by Mathy et al. (2015) which enables fast neighbor-based classification, regression and retrieval in large datasets. While boundary trees use an Euclidean measure of similarity, the Differentiable Boundary Tree algorithm by Zoran et al. (2017) was introduced to learn low-dimensional representations of complex input data, on which semantic similarity can be calculated to train boundary trees. As is pointed out by its authors, the differentiable boundary tree approach contains a few limitations that prevents it from scaling to large datasets. In this paper, we introduce Differentiable Boundary Sets, an algorithm that overcomes the computational issues of the differentiable boundary tree scheme and also improves its classification accuracy and data representability. Our algorithm is efficiently implementable with existing tools and offers a significant reduction in training time. We test and compare the algorithms on the well known MNIST handwritten digits dataset and the newer Fashion-MNIST dataset by Xiao et al. (2017).","Title: Anytime Stochastic Gradient Descent: A Time to Hear from all the Workers.\nYear: 2018\n\nAbstract: In this paper, we focus on approaches to parallelizing stochastic gradient descent (SGD) wherein data is farmed out to a set of workers, the results of which, after a number of updates, are then combined at a central master node. Although such synchronized SGD approaches parallelize well in idealized computing environments, they often fail to realize their promised computational acceleration in practical settings. One cause is slow workers, termed stragglers, who can cause the fusion step at the master node to stall, which greatly slowing convergence. In many straggler mitigation approaches work completed by these nodes, while only partial, is discarded completely. In this paper, we propose an approach to parallelizing synchronous SGD that exploits the work completed by all workers. The central idea is to fix the computation time of each worker and then to combine distinct contributions of all workers. We provide a convergence analysis and optimize the combination function. Our numerical results demonstrate an improvement of several factors of magnitude in comparison to existing methods.","Title: Introduction to the Issue on Information-Theoretic Methods in Data Acquisition, Analysis, and Processing.\nYear: 2018\n\nAbstract: The twenty papers that are included in this special section explore applications of information theoretic methods to emerging data science problems. In particular, the papers cover a wide range of topics that can broadly be organized into four themes: (1) data acquisition, (2) data analysis and processing, (3) statistics and machine learning, and (4) privacy and fairness.","Title: Bit-Interleaved Polar-Coded Modulation For Low-Latency Short-Block Transmission\nYear: 2017\n\nAbstract: We show that polar codes with list+CRC decoding can outperform state-of-the-art LDPC codes in short block lengths. In addition, we introduce an efficient interleaver for polar-coded high-order modulations, achieving greater than 0.5 dB gain for 256QAM.","Title: Irregular Polar Coding for Multi-Level Modulation in Complexity-Constrained Lightwave Systems\nYear: 2017\n\nAbstract: We introduce novel irregular polar codes, which extend the regular polar coding by flexible polarization pruning. We experimentally demonstrate that the proposed polar codes outperform state-of-the-art LDPC codes, while the computational complexity in encoding and decoding can be significantly reduced by at least 30% over the regular polar codes with a marginal performance improvement.","Title: Anytime Minibatch with Stale Gradients : (Invited Paper)\nYear: 2019\n\nAbstract: Large-scale machine learning problems are often solved using distributed optimization techniques by dividing tasks across multiple compute nodes. Due to variability in compute time amongst nodes, distributed systems suffer from slow nodes known as stragglers that can have a big impact on convergence speed. Recently, Anytime Minibatch (AMB) technique has been proposed to speed up convergence by exploiting work done by stragglers rather than avoiding them. In AMB, workers are given a fixed time to calculate gradients, followed by a fixed communication time to average gradients. We observe that nodes stay idle during communication time. In our work, we allow workers to compute gradients during communication time resulting in what is known as stale gradients due to gradients calculated on out-of-date parameters. Our simulation results show that such approach achieves up to 60% faster convergence in wall time.","Title: Compressing Gradients by Exploiting Temporal Correlation in Momentum-SGD\nYear: 2021\n\nAbstract: An increasing bottleneck in decentralized optimization is communication. Bigger models and growing datasets mean that decentralization of computation is important and that the amount of information exchanged is quickly growing. While compression techniques have been introduced to cope with the latter, none has considered leveraging the temporal correlations that exist in consecutive vector updates...","Title: Asynchronous Delayed Optimization With Time-Varying Minibatches\nYear: 2021\n\nAbstract: Large-scale learning and optimization problems are often solved in parallel. In a master-worker distributed setup, worker nodes are most often assigned fixed-sized minibatches of data points to process. However, workers may take different amounts of time to complete their per-batch calculations. To deal with such variability in processing times, an alternative approach has recently been proposed w...","Title: HIERARCHICAL CODED ELASTIC COMPUTING\nYear: 2021\n\nAbstract: Elasticity is offered by cloud service providers to exploit under-utilized computing resources. The low-cost elastic nodes can leave and join any time during the computation cycle. The possibility of elastic events occurring together with the problem of slow nodes, referred to as stragglers, increases the uncertainty of the system, leading to computation delay. Recent results have shown that coded computing can be used to reduce the negative effect of elasticity and stragglers. In this paper, we propose two hierarchical coded elastic computing schemes that can further speed up the system by exploiting stragglers and effectively allocating tasks among available nodes. In our simulations, our scheme realizes 45% improvement in average finishing time compared to the state-of-the-art coded elastic computing scheme.","Title: Probabilistic Shaping Using a Block-Based Bit-Level Distribution Matcher\nYear: 2022\n\nAbstract: We present a distribution matching architecture aimed at low-complexity probabilistic shaping. The scheme oper-ates by combining blocks of bits, generated in parallel by multiple binary distribution matchers, and mapping them to blocks of symbols from a non-binary alphabet. The proposed architecture constitutes a block-based generalization of the bit-level distribution matching (BL-DM) method. Namely, BL-DM corresponds to the particular case wherein single-bit blocks are used. While the computational complexity of our proposed scheme is effectively independent of the block size, larger block sizes can be used to realize a wider range of shaped output distributions, and in turn lead to an improved shaping performance. We demonstrate this benefit in our numerical simulations, which show that by using an increasingly larger block size, a lower per-shaped-symbol energy can be realized across all shaping rates and output blocklengths.","Title: SAPA: Sparse Affine Projection Algorithm in ADMM-LP Decoding of LDPC Codes\nYear: 2022\n\nAbstract: We present a simplified alternating direction method of multipliers with linear programming (ADMM-LP) decoder for LDPC codes by developing a method of approximate projection onto the parity polytope. The algorithm projects onto the affine hull of the \n<tex xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">$X$</tex>\n closest local codewords for each check of degree d, where \n<tex xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">$X$</tex>\n can be much smaller than d. We name this SAPA, the “sparse affine projection algorithm”. In contrast to exact projection, SAPA does not require a water-filling step and thus can be implemented with lower per-iteration complexity. We present numerical results which demonstrate not only that SAPA's performance, when used as part of an overall decoder, is close to that of exact projection, but also that the use of SAPA does not incur many additional iterations. This is in contrast to other approximate algorithms. Thus, SAPA is appropriate for use in limited-iteration decoders in high-throughput applications. Moreover, we analyze sparsity of polytope projections in the exact ADMM-LP decoding to explain the suitability of the proposed sparse approximation."],"string":"[\n \"Title: Universal Anytime Coding\\nYear: 2007\\n\\nAbstract: We show the existence of codes for anytime coding over compound channels - i.e. codes that operate without knowledge of the transition probabilities of the communication channel. The anytime error exponent achieved is the same as if the decoder were given the probabilities governing the realized channel and allowed to do maximum likelihood decoding. Because of the equivalence between system stabilization over noisy feedback channels and communication over noisy channels, the results immediately give sufficient conditions for stabilization over compound channels.\",\n \"Title: Notary: Hardware techniques to enhance signatures\\nYear: 2008\\n\\nAbstract: Hardware signatures have been recently proposed as an efficient mechanism to detect conflicts amongst concurrently running transactions in transactional memory systems (e.g., Bulk, LogTM-SE, and SigTM). Signatures use fixed hardware to represent an unbounded number of addresses, but may lead to false conflicts (detecting a conflict when none exists). Previous work recommends that signatures be implemented with parallel Bloom filters with two or four hash functions (e.g., H3).\",\n \"Title: Minimizing total area of low-voltage SRAM arrays through joint optimization of cell size, redundancy, and ECC\\nYear: 2010\\n\\nAbstract: The increasing power consumption of processors has made power reduction a first-order priority in their design. Voltage scaling is one of the most successful power-reduction techniques introduced to date, but it is limited to some minimum voltage, VDDMIN, below which all components cannot operate reliably. In particular, ever-increasing process variability due to shrinking feature size further degrades the low-voltage reliability of, e.g., SRAM cells. Larger SRAM cells are less sensitive to process variability and their use would allow a reduction in VDDMIN. However, large-scale memory structures, e.g., last-level caches (LLCs) that often determine the VDDMIN of processors, cannot afford to use such large SRAM cells due to the resulting increase in die area. In this paper we propose a joint optimization of LLC cell size, number of redundant cells, and ECC (error-correction coding) strength to minimize total SRAM area while meeting target yields and VDDMIN. The use of redundant cells and ECC enable the use of smaller cell sizes while maintaining target yields and VDDMIN. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. We first assess each approach individually, i.e., only redundancy or ECC for various cell sizes. We then consider a combined approach and observe significant improvements. For example, in 32nm technology our combined approach yields a 27% reduction in total SRAM area (including redundant cells) when targeting a VDDMIN of 600mV.\",\n \"Title: On Compression of Encrypted Video\\nYear: 2007\\n\\nAbstract: We consider video sequences that have been encrypted uncompressed. Since encryption masks the source, traditional data compression algorithms are rendered ineffective. However, it has been shown that through the use of distributed source-coding techniques, the compression of encrypted data is in fact possible. This means that it is possible to reduce data size without requiring that the data be compressed prior to encryption. Indeed, under some reasonable conditions, neither security nor compression efficiency need be sacrificed when compression is performed on the encrypted data (Johnson et al., 2004). In this paper we develop an algorithm for the practical lossless compression of encrypted gray scale video. Our method is based on considering the temporal correlations in video. This move to temporal dependence builds on our previous work on memoryless sources, and one- and two-dimensional Markov sources. For comparison, a motion-compensated lossless video encoder can compress each unencrypted frame of the standard \\\"Foreman test video sequence by about 57%. Our algorithm can compress compress the same frames, after encryption, by about 33%.\",\n \"Title: QUEUING WITH DISTORTION-CONTROL FOR MULTIMEDIA CONTENT\\nYear: 2002\\n\\nAbstract: There are numerous contexts in which systems need to buffer multimedia signal content. If such a buffer overflo ws, sig- nal data are lost in an uncontrolled manner, which can lead to large end-to-end distortions. However, if the queued sig- nals are distortion-tolerant, overflo ws can be avoided, and significant performance gains realized, by reducing the fi- delity of the signals in a gradual, controlled, manner. Based on ideas of successive-approximation source coding, we de- sign an adaptive-buffering algorithm to minimize end-to- end distortion. This algorithm performs nearly as well as a performance bound on all possible algorithms. Perhaps most importantly, the algorithm' s performance remains ro- bust across a wide range of (unpredictable) utilization rates (input rate/output rate).\",\n \"Title: On reliability of content identification from databases based on noisy queries.\\nYear: 2011\\n\\nAbstract: In this paper we quantify an achievable error-exponent for the problem of content identification from a large database based on noisy queries.\",\n \"Title: Secret key generation through OFDM multipath channel\\nYear: 2011\\n\\nAbstract: We analyze the fundamental limits of key generation and describe an implementation based on error correcting codes. We show that key extraction based on channel coefficients significantly outperforms key extraction based on received signal strength indicators (RSSI). The development in this paper is based on an IEEE 802.11a orthogonal frequency-division multiplexing (OFDM) model and We demonstrate that it is feasible to use the sampled channel coefficients in OFDM as the key source. The key extraction problem is cast as a Slepian-Wolf coding and decoding problem. We construct regular and irregular forms of binary and non-binary low-density parity check (LDPC) codes to prototype our key extraction.\",\n \"Title: Queuing theoretic analysis of power-performance tradeoff in power-efficient computing\\nYear: 2013\\n\\nAbstract: In this paper we study the power-performance relationship of power-efficient computing from a queuing theoretic perspective. We investigate the interplay of several system operations including processing speed, system on/off decisions, and server farm size. We identify that there are oftentimes 'sweet spots' in power-efficient operations: there exist optimal combinations of processing speed and system settings that maximize power efficiency. For the single server case, a widely deployed threshold mechanism is studied. We show that there exist optimal processing speed and threshold value pairs that minimize the power consumption. This holds for the threshold mechanism with job batching. For the multi-server case, it is shown that there exist best processing speed and server farm size combinations.\",\n \"Title: An analysis of empirical PMF based tests for least significant bit image steganography\\nYear: 2005\\n\\nAbstract: We consider here the class of probability mass-function (PMF) based detectors of least significant bit (LSB) embedded steganography. That is, in this paper we investigate the use of frequency counts of pixel intensities as a statistic for tests detecting the presence of hidden messages. We focus on LSB replacement (though we briefly consider LSB matching) embedding as it is a simple technique where the effect on the true PMF of the resulting image can be understood mathematically. We begin our study by considering the existing tests of Westfeld and Pfitzmann [11] and Dabeer et al.[1]. These tests assume that pixel intensities are random values that are independent and identically distributed (i.i.d.). We generalize these tests by considering PMFs of neighboring pixel intensities. We argue that consideration of higher order of correlations provide only diminishing marginal returns, and thus we can make general statements on the value of PMF based detectors. We measure the performance of our tests by calculation of receiver operating curves (ROC) over a corpus of 350 digital images. We then proceed to compare to a non-PMF based test, in particular the RS tests of Fridrich et al [3]. Although our generalized tests outperform existing PMF based predecessors, they are outperformed by the RS tests. This indicates that using PMFs as a statistic for detecting hidden messages is inherently insufficient.\",\n \"Title: Unequal Message Protection: Asymptotic and Non-Asymptotic Tradeoffs.\\nYear: 2014\\n\\nAbstract: We study a form of unequal error protection that we term unequal message protection (UMP). The message set of a UMP code is a union of m disjoint message classes. Each class has its own error protection requirement, with some classes needing better error protection than others. We analyze the tradeoff between rates of message classes and the levels of error protection; our analysis reveals new tradeoffs, which were not captured by prior works on UMP codes. To obtain our results, we generalize finite block length achievability and converse bounds due to Polyanskiy-Poor-Verdú. We evaluate our bounds for the binary symmetric and binary erasure channels, and analyze the asymptotic characteristic of the bounds in the fixed error and moderate deviations regimes. In addition, we consider two questions related to the practical construction of UMP codes. First, we study a header construction that prefixes the message class into a header followed by data protection using a standard homogeneous (classical) code. We show that, in general, this construction is not optimal at finite block lengths. We further demonstrate that our main UMP achievability bound can be obtained using coset codes, which suggests a path to implementation of tractable UMP codes.\",\n \"Title: Cooperative Packet Routing using Mutual Information Accumulation\\nYear: 2011\\n\\nAbstract: We consider the resource allocation problem in cooperative wireless networks wherein nodes perform mutual information accumulation. We consider a unicast setting and arbitrary arrival processes at the source node. Source arrivals can be broken down into numerous packets to better exploit the spatial and temporal diversity of the routes available in the network. We devise a linear-program-based algorithm which allocates network resource to meet a certain transmission objective. Given a network, a source with multiple arriving packets and a destination, our algorithm generates a policy that regulates which nodes should participate in transmitting which packets, when and with what resource. By routing different packets through different nodes the policy exploits spatial route diversity, and by sequencing packet transmissions along the same route it exploits temporal route diversity.\",\n \"Title: Divide and Concur and Difference-Map BP Decoders for LDPC Codes\\nYear: 2011\\n\\nAbstract: The “Divide and Concur” (DC) algorithm introduced by Gravel and Elser can be considered a competitor to the belief propagation (BP) algorithm, in that both algorithms can be applied to a wide variety of constraint satisfaction, optimization, and inference problems. We show that DC can be interpreted as a message-passing algorithm on a “normal” factor graph. The “difference-map” dynamics of the DC algorithm enables it to avoid “traps” which may be related to the “trapping sets” or “pseudo-codewords” that plague BP decoders of low-density parity check (LDPC) codes in the error-floor regime. We investigate two decoders for LDPC codes based on these ideas. The first decoder is based directly on DC, while the second decoder borrows the important “difference-map” concept from the DC algorithm and translates it into a BP-like decoder. We show that this “difference-map belief propagation” (DMBP) decoder has dramatically improved error-floor performance compared to standard BP decoders, while maintaining a similar computational complexity. We present simulation results for LDPC codes comparing DC and DMBP decoders with other decoders based on sum-product BP, linear programming, and mixed-integer linear programming. We also describe the close relation of the DMBP decoder to reweighted min-sum algorithms, including those recently proposed by Ruozzi and Tatikonda.\",\n \"Title: Optimal scheduling policies with mutual information accumulation in wireless networks\\nYear: 2012\\n\\nAbstract: In this paper, we aim to develop scheduling policies to maximize the stability region of a wireless network under the assumption that mutual information accumulation is implemented at the physical layer. This enhanced physical layer capability enables the system to accumulate information even when the link between two nodes is not good and a packet cannot be decoded within a slot. The result is an expansion of the stability region of the system. The accumulation process does not satisfy the i.i.d assumption that underlies many previous analysis in this area. Therefore it also brings new challenges to the problem. We propose two dynamic scheduling algorithms to overcome this difficulty. One performs scheduling every T slot, which inevitably increases average delay in the system, but approaches the boundary of the stability region. The second constructs a virtual system with the same stability region. Through controlling the virtual queues in the constructed system, we avoid the non-i.i.d difficulty and attain the stability region. We derive performance bounds under both algorithms and compare them through simulation results.\",\n \"Title: The l1 penalized decoder and its reweighted LP\\nYear: 2012\\n\\nAbstract: Linear programming (LP) decoding for low density parity check (LDPC) codes proposed by Feldman et al. has attracted considerable attention in recent years. Despite having theoretical guarantees in some regimes, at low SNRs LP decoding is observed to have worse error performance than belief propagation (BP) decoding. In this paper, we present a novel decoding algorithm obtained by trying to solve a non-convex optimization problem using the alternating direction method of multipliers (ADMM). This non-convex problem is constructed by adding an ℓ1 penalty term to the LP decoding objective. The goal of the penalty term is to make “pseudocodewords”, which are the non-integer vertices of the LP relaxation to which the LP decoder fails, more costly. We name this the “ℓ1 penalized decoder”. We also develop a reweighted LP decoding algorithm base on this ℓ1 penalized objective. We show that this reweighted LP has an improved theoretical recovery threshold compared to the original LP. In addition, simulations show that, in comparison to LP decoding, these two decoders both achieve significantly lower error rates and are not observed to have an “error floor”. In particular, the ℓ1 penalized decoder meets or outperforms the BP decoder at all SNRs.\",\n \"Title: Compressed sensing over finite fields\\nYear: 2009\\n\\nAbstract: We develop compressed sensing results for sources drawn from finite alphabets. We apply tools from linear coding and large deviations. We establish strong connections between our results and error exponents of lossless source coding in the case of no measurement noise, and modified channel coding error exponents in the case of measurement noise. We connect to standard results on compressed sensing in the real field.\",\n \"Title: Exploiting route diversity in multi-packet transmission using mutual information accumulation\\nYear: 2011\\n\\nAbstract: We consider the resource allocation problem in cooperative wireless networks wherein nodes perform mutual information accumulation. We consider a unicast setting and arbitrary arrival processes at the source node. Source arrivals can be broken down into numerous packets to better exploit the spatial and temporal diversity of the routes available in the network. We devise a linear-program-based algorithm which al locates network resource to meet a certain transmission objective. Given a network, a source with multiple arriving packets and a destination, our algorithm generates a policy that regulates which nodes should participate in transmitting which packets, when and with what resource. By routing different packets through different nodes the policy exploits spatial route diversity, and by sequencing packet transmissions along the same route it exploits temporal route diversity.\",\n \"Title: Hierarchical and High-Girth QC LDPC Codes\\nYear: 2013\\n\\nAbstract: We present an approach to designing capacity-approaching high-girth low-density parity-check (LDPC) codes that are friendly to hardware implementation, and compatible with some desired input code structure defined using a protograph. The approach is based on a mapping of any class of codes defined using a protograph into a family of hierarchical quasi-cyclic (HQC) LDPC codes. Whereas the parity check matrices of standard quasi-cyclic (QC) LDPC codes are composed of circulant submatrices, those of HQC LDPC codes are composed of a hierarchy of circulant submatrices that are, in turn, constructed from circulant submatrices, and so on, through some number of levels. Next, we present a girth-maximizing algorithm that optimizes the degrees of freedom within the family of codes to yield a high-girth HQC LDPC code, subject to bounds imposed by the fact that HQC codes are still quasi-cyclic. Finally, we discuss how certain characteristics of a code protograph will lead to inevitable short cycles and show that these short cycles can be eliminated using a “squashing” procedure that results in a high-girth QC LDPC code, although not a hierarchical one. We illustrate our approach with three design examples of QC LDPC codes—two girth-10 codes of rates $1/3$ and 0.45 and one girth-8 code of rate 0.7—all of which are obtained from protographs of one-sided spatially coupled codes.\",\n \"Title: A Theoretical Analysis of Authentication, Privacy, and Reusability Across Secure Biometric Systems\\nYear: 2011\\n\\nAbstract: We present a theoretical framework for the analysis of privacy and security trade-offs in secure biometric authentication systems. We use this framework to conduct a comparative information-theoretic analysis of two biometric systems that are based on linear error correction codes, namely fuzzy commitment and secure sketches. We derive upper bounds for the probability of false rejection $(P_{FR})$ and false acceptance $(P_{FA})$ for these systems. We use mutual information to quantify the information leaked about a user's biometric identity, in the scenario where one or multiple biometric enrollments of the user are fully or partially compromised. We also quantify the probability of successful attack $(P_{SA})$ based on the compromised information. Our analysis reveals that fuzzy commitment and secure sketch systems have identical $P_{FR}$ , $P_{FA}$ , $P_{SA}$ , and information leakage, but secure sketch systems have lower storage requirements. We analyze both single-factor (keyless) and two-factor (key-based) variants of secure biometrics, and consider the most general scenarios in which a single user may provide noisy biometric enrollments at several access control devices, some of which may be subsequently compromised by an attacker. Our analysis highlights the revocability and reusability properties of key-based systems and exposes a subtle design trade-off between reducing information leakage from compromised systems and preventing successful attacks on systems whose data have not been compromised.\",\n \"Title: Variable-length channel coding with noisy feedback\\nYear: 2008\\n\\nAbstract: It is known that perfect noiseless feedback can be used to improve the reliability of communication systems. We show how to make those gains robust to noise on the feedback link. We focus on feedback links that are themselves discrete memoryless channels. We demonstrate that Forney's erasure-decoding exponent is achievable given any positive-capacity feedback channel. We also demonstrate that as the desired rate of communication approaches the capacity of the forward channel, the Burnashev upper bound on the reliability function is achievable given any positive-capacity noisy feedback channel. Finally, we demonstrate that our scheme dominates the erasure-decoding exponent at all rates and, for instance, at zero rate can achieve up to three-quarters of Burnashev's zero-rate reliability. This implies that in a shared medium, to maximise the reliability function some degrees of freedom should be allocated to feedback. Copyright (C) 2008 John Wiley & Sons, Ltd.\",\n \"Title: Low-voltage on-chip cache architecture using heterogeneous cell sizes for high-performance processors\\nYear: 2011\\n\\nAbstract: To date dynamic voltage/frequency scaling (DVFS) has been one of the most successful power-reduction techniques. However, ever-increasing process variability reduces the reliability of static random access memory (SRAM) at low voltages. This limits voltage scaling to a minimum operating voltage (VDDMIN). Larger SRAM cells, that are less sensitive to process variability, allow the use of lower VDDMIN. However, large-scale memory structures, e.g., the last-level cache (LLC) (that often determines the VDDMIN of the processor), cannot afford to use such large SRAM cells due to the die area constraint. In this paper we propose low-voltage LLC architectures that exploit 1) the DVFS characteristics of workloads running on high-performance processors, 2) the trade-off between SRAM cell size and VDDMIN, and 3) the fact that at lower voltage/frequency operating states the negative performance impact of having a smaller LLC capacity is reduced. Our proposed LLC architectures provide the same maximum performance and VDDMIN as the conventional architecture, while reducing the total LLC cell area by 15%--19% with negligible average runtime increase.\",\n \"Title: Impact of channel sparsity and correlated eavesdropping on secret key generation from multipath channel randomness\\nYear: 2010\\n\\nAbstract: We study secret key generation from reciprocal multipath wireless channels modeled as multiple parallel fading channels. We consider two channel characteristics that heavily impact secret key capacity: channel sparsity and correlation between main and eavesdropper's channels. We propose a joint model to capture the channel sparsity and correlated eavesdropping. For the case without eavesdroppers, we show that at each transmitter SNR γ there is an optimal sparsity 0 ≤ ρopt ≤ 1, which specifies the fraction of non-zero channel coefficients, that yields the maximum secret key capacity. The reduction in secret key capacity due to eavesdropping is due to two sources. First is the overlap between the main and eavesdropper channels, i.e., the pattern of non-zero subchannels common to both. The second is the correlation between the channel coefficients of the overlapping channels. We show that when the power of the training signal is uniformly distributed over the non-zero channels, there is a cutoff SNR γc below which the secret key rate is zero, but non-zero (and increasing in γ) when γ > γc. We also show that in the low SNR regime, the optimal input signal is peaky (a non-uniform training signal) by which the secret key capacity is non-zero at all γ > 0.\",\n \"Title: Noisy feedback improves communication reliability\\nYear: 2006\\n\\nAbstract: We show how to exploit a noisy feedback link to implement high-reliability communication. We specify a variable-length coding strategy that achieves the error exponent (in delay) of erasure decoding using any noisy feedback channel which has a positive zero-rate random coding error exponent. Building on this result, we give a second approach that, depending only on the capacity of the feedback link, achieves an error exponent up to half of the Burnashev exponent—the maximum exponent that can be achieved with a noiseless feedback link. The resulting exponent can be far larger than the exponent of erasure decoding, particularly at rates close to capacity. I. I NTRODUCTION Feedback is present in many deployed communication systems and yet the theory of feedback has made little impact on communications in practice. In part this is be- cause the models of instantaneous and noiseless feedback often assumed in theory do not match the delayed and noisy feedback usually available in practice. In this paper we look at one of the promised benefits of feedback— large increases in the reliability of communications over discrete memoryless channels (DMCs). We show that, to some degree, this benefit can still be realized even when the feedback link is itself a noisy channel. Essentially feedback makes it possible to increase the reliability of communication over a DMC because it enables the use of variable-length transmission. If the system detects that the channel noise has been atypically bad for the duration of transmission, it refrains from decoding until the channel appears to have improved. In contrast, in systems without feedback the duration of transmission must be fixed. Even if the channel noise is bad for the entire duration, the decoder has no option but to decode. We compare coding strategies based on their reliability functions (or error exponents), calculated in terms of the expected decoding delay. This is the length of time from when the source begins transmitting a message to when the destination makes a final decision. This function is logPr(error)/E (t).\",\n \"Title: Analyzing the impact of joint optimization of cell size, redundancy, and ECC on low-voltage SRAM array total area\\nYear: 2012\\n\\nAbstract: The increasing power consumption of processors has made power reduction a first-order priority in processor design. Voltage scaling is one of the most powerful power-reduction techniques introduced to date, but is limited to some minimum voltage VDDMIN. Below VDDMIN on-chip SRAM cells cannot all operate reliably due to increased process variability with technology scaling. The use of larger SRAM cells, which are less sensitive to process variability, allows a reduction in VDDMIN. However, since the large-scale memory structures such as last-level caches (LLCs) often determine the VDDMIN of processors, these structures cannot afford to use large SRAM cells due to the resulting increase in die area. In this paper we first propose a joint optimization of LLC cell size, the number of redundant cells, and the strength of error-correction coding (ECC) to minimize total SRAM area while meeting yield and targets. The joint use of redundant cells and ECC enables the use of smaller cell sizes while maintaining design targets. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. In 32-nm technology our joint approach yields a 27% reduction in total SRAM area (including the extra cells) when targeting 90% yield and 600 mV VDDMIN. Second, we demonstrate that the ECC used to repair defective cells can be combined with a simple architectural technique, which can also fix particle-induced soft errors, without increasing ECC strength or processor runtime.\",\n \"Title: Cooperative Routing for Wireless Networks using Mutual-Information Accumulation\\nYear: 2009\\n\\nAbstract: Cooperation between the nodes of wireless multihop networks can increase\\ncommunication reliability, reduce energy consumption, and decrease latency. The\\npossible improvements are even greater when nodes perform mutual information\\naccumulation using rateless codes. In this paper, we investigate routing\\nproblems in such networks. Given a network, a source, and a destination, our\\nobjective is to minimize end-to-end transmission delay under energy and\\nbandwidth constraints. We provide an algorithm that determines which nodes\\nshould participate in forwarding the message and what resources (time, energy,\\nbandwidth) should be allocated to each.\\n Our approach factors into two sub-problems, each of which can be solved\\nefficiently. For any transmission order we show that solving for the optimum\\nresource allocation can be formulated as a linear programming problem. We then\\nshow that the transmission order can be improved systematically by swapping\\nnodes based on the solution of the linear program. Solving a sequence of linear\\nprograms leads to a locally optimal solution in a very efficient manner. In\\ncomparison to the proposed cooperative routing solution, it is observed that\\nconventional shortest path multihop routing typically incurs additional delays\\nand energy expenditures on the order of 70%.\\n Our first algorithm is centralized, assuming that routing computations can be\\ndone at a central processor with full access to channel state information for\\nthe entire system. We also design two distributed routing algorithms that\\nrequire only local channel state information. We provide simulations showing\\nthat for the same networks the distributed algorithms find routes that are only\\nabout two to five percent less efficient than the centralized algorithm.\",\n \"Title: Exploiting Channel Diversity in Secret Key Generation From Multipath Fading Randomness\\nYear: 2012\\n\\nAbstract: We design and analyze a method to extract secret keys from the randomness inherent to wireless channels. We study a channel model for a multipath wireless channel and exploit the channel diversity in generating secret key bits. We compare the key extraction methods based both on entire channel state information (CSI) and on single channel parameter such as the received signal strength indicators (RSSI). Due to the reduction in the degree-of-freedom when going from CSI to RSSI, the rate of key extraction based on CSI is far higher than that based on RSSI. This suggests that exploiting channel diversity and making CSI information available to higher layers would greatly benefit the secret key generation. We propose a key generation system based on low-density parity-check (LDPC) codes and describe the design and performance of two systems: one based on binary LDPC codes and the other (useful at higher signal-to-noise ratios) based on four-ary LDPC codes.\",\n \"Title: Secret Key Generation from Sparse Wireless Channels: Ergodic Capacity and Secrecy Outage\\nYear: 2013\\n\\nAbstract: This paper investigates generation of a secret key from a reciprocal wireless channel. In particular we consider wireless channels that exhibit sparse structure in the wideband regime and study the impact of sparsity on the secret key capacity. We explore this problem in two steps. First, we study key generation from a state-dependent discrete memoryless multiple source. The state of the source captures the effect of channel sparsity. Secondly, we consider a wireless channel model that captures channel sparsity and correlation between the legitimate users' channel and the eavesdropper's channel. Such dependency can significantly reduce the secret key capacity. According to system delay requirements, two performance measures are considered: (i) ergodic secret key capacity and (ii) outage probability. We show that in the wideband regime when a white sounding sequence is adopted, a sparser channel can achieve a higher ergodic secret key rate than a richer channel can. For outage performance, we show that if the users generate secret keys at a fraction of the ergodic capacity, the outage probability will decay exponentially in signal bandwidth. Moreover, a larger exponent is achieved by a richer channel.\",\n \"Title: Lossless Coding For Distributed Streaming Sources\\nYear: 2006\\n\\nAbstract: Distributed source coding is traditionally viewed in a block coding context wherein all source symbols are known in advance by the encoders. However, many modern applications to which distributed source coding ideas are applied, are better modeled as having streaming data. In a streaming setting, source symbol pairs are revealed to separate encoders in real time and need to be reconstructed at the decoder with subject to some tolerable end-to-end delay. In this paper, a causal sequential random binning encoder is introduced and paired with maximum likelihood (ML) and universal decoders. The latter uses a novel weighted empirical suffix entropy decoding rule. We derive a lower bounds on the error exponent with delay for each decoder. We also provide upper bounds for the special case of streaming with decoder side information and discuss when upper and lower bounds match. We show that both ML and universal decoders achieve the same (positive) error exponents for all rate pairs inside the Slepian-Wolf achievable rate region. The dominant error events in streaming are different from those in block-coding and result in different exponents. Because the sequential random binning scheme is also universal over delays, the resulting code eventually reconstructs every source symbol correctly with probability one.\",\n \"Title: SleepScale: runtime joint speed scaling and sleep states management for power efficient data centers\\nYear: 2014\\n\\nAbstract: Power consumption in data centers has been growing significantly in recent years. To reduce power, servers are beingequipped with increasingly sophisticated power management mechanisms. Different mechanisms offer dramatically different trade-offs between power savings and performance penalties. Considering the complexity, variety, and temporallyvarying nature of the applications hosted in a typical data center, intelligently determining which power management policy to use and when is a complicated task.\\n\\nIn this paper we analyze a system model featuring both performance scaling and low-power states. We reveal the interplay between performance scaling and low-power states via intensive simulation and analytic verification. Based on the observations, we present SleepScale, a runtime power management tool designed to efficiently exploit existing power control mechanisms. At run time, SleepScale characterizes power consumption and quality-of-service (QoS) for each lowpower state and frequency setting, and selects the best policy for a given QoS constraint. We evaluate SleepScale using workload traces from data centers and achieve significant power savings relative to conventional power management strategies\",\n \"Title: Key Generation Using External Source Excitation: Capacity, Reliability, and Secrecy Exponent\\nYear: 2012\\n\\nAbstract: We study the fundamental limits to secret key generation from an excited distributed source (EDS). In an EDS, a pair of terminals observe dependent sources of randomness excited by a pre-arranged signal. We first determine the secret key capacity for such systems with one-way public messaging. We then characterize a tradeoff between the secret key rate and exponential bounds on the probability of key agreement failure and on the secrecy of the key generated. We find that there is a fundamental tradeoff between reliability and secrecy.\",\n \"Title: The sender-excited secret key agreement model: Capacity theorems\\nYear: 2011\\n\\nAbstract: We consider the fundamental limits of the secret key generation problem when the sources are excited by the sender. In many practical communication settings, the channel may be influenced by the parties involved. Similar to recent works on probing capacity and channels with action-dependent states, our system model captures such a scenario. We derive single-letter expressions for the secret key capacity. Our coding strategy involves wiretap channel coding and a key generation scheme. By assuming that the eavesdropper receives a degraded version of the legitimate receiver's observation, we also obtain a capacity result that does not involve any auxiliary random variables. Finally, by studying two examples, we show that there is a fundamental tradeoff in between the amount of common randomness (i.e., the secret key rate) and the wiretap secrecy rate.\",\n \"Title: Routing In Cooperative Wireless Networks With Mutual-Information Accumulation\\nYear: 2008\\n\\nAbstract: Cooperation between the nodes of wireless multi-hop networks can increase communication reliability, reduce energy consumption, and decrease latency. The possible improvements are even greater when nodes perform mutual-information accumulation, e.g., by using rateless codes. In this paper, we investigate routing problems in such networks. Given a network, a source and a destination, our objective is to minimize end-to-end transmission delay under a sum energy constraint. We provide an algorithm that determines which nodes should participate in forwarding the message and what resources (time, energy, bandwidth) should be allocated to each. Our approach factors into two sub-problems, each of which can be solved efficiently. For any node decoding order we show that solving for the optimum resource allocation can be formulated as a linear problem. We then show that the decoding order can be improved systematically by swapping nodes based on the solution of the linear program. Solving a sequence of linear program leads to a locally optimum solution in a very efficient manner. In comparison to the cooperative routings, it is observed that conventional shortest-path multihop routings incur additional delays and energy expenditures on the order of 70%. Since this initial solution is centralized, requiring full channel state information, we exploit the insights to design two distributed routing algorithms that require only local channel state information. We provide simulations showing that in the same networks the distributed algorithms find routes that are only about 2 - 5% less efficient than the centralized solution.\",\n \"Title: Passive learning of the interference graph of a wireless network\\nYear: 2012\\n\\nAbstract: A key challenge in wireless networking is the management of interference between transmissions. Identifying which transmitters interfere with each other is crucial. Complicating this task is the fact that the topology of wireless networks can change from time to time, and so the identification process may need to be carried out on a regular basis. Injecting active probing traffic to assess interference can lead to unacceptable overhead, and so this paper focuses on interference estimation based on passive traffic monitoring in networks that use the CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) protocol. A graph is used to represent the interference in the network, where the nodes represent transmitters and edges represent interference between pairs of transmitters. We investigate the problem of learning the graph structure based on passive observations of network traffic transmission patterns and information about successes or failures in transmissions. Previous work has focused on algorithms and validations in small testbed networks. This paper focuses on the scaling behavior of such methods which is unaddressed in prior work. In particular we establish bounds on the minimum observation period required to identify the interference graph reliably. The main results are expressed in terms of the total number of nodes n and the maximum number of interfering transmitters per node (i.e., maximum node degree) d. The effects of hidden terminal interference (i.e., interference not detectable via carrier sensing) on the observation time requirement are also quantified. We show that it is necessary and sufficient that the observation period grows like d2 log n, and we propose a practical algorithm that reliably identifies the graph from this length of observation. We conclude that the observation requirements scale quite mildly with network size, and that the networks with sparse interference patterns can be more rapidly identified than those with de- se interference patterns.\",\n \"Title: Minimum energy per bit for secret key acquisition over multipath wireless channels\\nYear: 2009\\n\\nAbstract: We study fundamental limits on the generation of secret keys based on the randomness inherent to reciprocal wireless multipath channels. Estimates of the common channel at the two ends of a link are jointly Gaussian sources from which secret keys can be generated. The key generation problem is cast as an equivalent communication problem to characterize the secret key capacity. We analyze the low-SNR regime to quantify the minimum energy per secret key bit required for reliable key acquisition. Our results show that, in contrast to the low SNR behavior of conventional channel capacity, there is a non-zero SNR γ* that achieves the minimum energy per key bit. A time-sharing scheme is proposed to achieve the minimum energy per key bit at any SNR below γ*. We also investigate the reliability of secret key generation via error exponent analysis. In particular, our results yield a tight upper bound on the minimum energy required to generate a finite-length key with a specified probability of error in key acquisition.\",\n \"Title: An information-theoretic analysis of revocability and reusability in secure biometrics\\nYear: 2011\\n\\nAbstract: Secure biometric systems are designed to allow authentication without requiring a reference biometric sample to be stored in the clear at the access control device. Instead, a template extracted from the reference biometric is stored on the device. An enrolled user can be authenticated by the template combined with a legitimate test biometric. However, an attacker who infiltrates the device only discovers the template, which reveals little or no information about the true biometric. We present a general framework for secure biometric authentication systems, and then provide a comparative information-theoretic analysis of two related realizations: (1) fuzzy commitment, in which authentication is framed as a problem of correcting errors between the reference and test biometrics, and (2) secure sketches, in which authentication is framed as a Slepian-Wolf decoding problem. We derive the false reject rates, false accept rates and successful attack rates for both realizations. We also consider the information leaked about a user's biometric identity when the database of biometric templates is compromised. Finally, we analyze a scenario in which the same biometric has been used to generate templates for several access control devices, some of which have been compromised by an adversary. It is shown that, two-factor versions of fuzzy commitment and secure sketch not only allow revocability, but also provide resistance to attacks in which the adversary compromises several databases at the same time.\",\n \"Title: Optimal Backpressure Scheduling in Wireless Networks using Mutual Information Accumulation\\nYear: 2011\\n\\nAbstract: In this paper we develop scheduling policies that maximize the stability region of a wireless network under the assumption that mutual information accumulation is implemented at the physical layer. When the link quality between nodes is not sufficiently high that a packet can be decoded within a single slot, the system can accumulate information across multiple slots, eventually decoding the packet. The result is an expanded stability region. The accumulation process over weak links is temporally coupled and therefore does not satisfy the independent and identically distributed (i.i.d) assumption that underlies many previous analysis in this area. Therefore the problem setting also poses new analytic challenges. We propose two dynamic scheduling algorithms to cope with the non-i.i.d nature of the decoding. The first performs scheduling every $T$ slots, and approaches the boundary of the stability region as $T$ gets large, but at the cost of increased average delay. The second introduces virtual queues for each link and constructs a virtual system wherein two virtual nodes are introduced for each link. The constructed virtual system is shown to have the same stability region as the original system. Through controlling the virtual queues in the constructed system, we avoid the non-i.i.d analysis difficulty and attain the full stability region. We derive performance bounds for both algorithms and compare them through simulation results.\",\n \"Title: The Sender-Excited Secret Key Agreement Model: Capacity, Reliability, and Secrecy Exponents\\nYear: 2015\\n\\nAbstract: We consider the secret key generation problem when sources are randomly excited by the sender and there is a noiseless public discussion channel. Our setting is thus similar to recent works on channels with action-dependent states, where the channel state may be influenced by some of the parties involved. We derive single-letter expressions for the secret key capacity through a type of source emulation analysis. We also derive lower bounds on the achievable reliability and secrecy exponents, i.e., the exponential rates of decay of the probability of decoding error and of the information leakage. These exponents allow us to determine a set of strongly achievable secret key rates. For degraded eavesdroppers, the maximum strongly achievable rate equals the secret key capacity; our exponents can also be specialized to previously known results. In deriving our strong achievability results, we introduce a coding scheme that combines wiretap coding (to excite the channel) and key extraction (to distill keys from residual randomness). The secret key capacity is naturally seen to be a combination of both source- and channel-type randomness. Through examples, we illustrate a fundamental interplay between the portion of the secret key rate due to each type of randomness. We also illustrate inherent tradeoffs between the achievable reliability and secrecy exponents. Our new scheme also naturally accommodates rate limits on the public discussion. We show that under rate constraints, we are able to achieve larger rates than those that can be attained through a pure source emulation strategy.\",\n \"Title: The ADMM penalized decoder for LDPC codes.\\nYear: 2014\\n\\nAbstract: Linear programming (LP) decoding for low-density parity-check codes was introduced by Feldman et al. and has been shown to have theoretical guarantees in several regimes. Furthermore, it has been reported in the literature-via simulation and via instanton analysis-that LP decoding displays better error rate performance at high signal-to-noise ratios (SNR) than does belief propagation (BP) decoding...\",\n \"Title: LP-decodable multipermutation codes\\nYear: 2014\\n\\nAbstract: In this paper, we introduce a new way of constructing and decoding multipermutation codes. Multipermutations are permutations of a multiset that may consist of duplicate entries. We first introduce a new class of matrices called multipermutation matrices. We characterize the convex hull of multipermutation matrices. Based on this characterization, we propose a new class of codes that we term LP-decodable multipermutation codes. Then, we derive two LP decoding algorithms. We first formulate an LP decoding problem for memoryless channels. We then derive an LP algorithm that minimizes the Chebyshev distance. Finally, we show a numerical example of our algorithm.\",\n \"Title: Suppressing pseudocodewords by penalizing the objective of LP decoding\\nYear: 2012\\n\\nAbstract: In this paper, we present a new class of decoders for low density parity check (LDPC) codes. We are motivated by the observation that the linear programming (LP) decoder has worse error performance than belief propagation (BP) decoders at low SNRs. We base our new decoders on the alternating direction method of multipliers (ADMM) decomposition technique for LP decoding. The ADMM not only efficiently solves the LP decoding problem, but also makes it possible to explore other decoding algorithms. In particular, we add various penalty terms to the linear objective of LP decoding with the goal of suppressing pseudocodewords. Simulation results show that the new decoders achieve much better error performance compared to LP decoder at low SNRs. What is more, similar to the LP decoder, no error floor is observed at high SNRs.\",\n \"Title: Instanton search algorithm for the ADMM penalized decoder\\nYear: 2014\\n\\nAbstract: Linear programming (LP) decoding using the alternating direction method of multipliers (ADMM) has been shown to be an efficient algorithm. A non-convex variation based on the ADMM LP decoder called the ADMM penalized decoder was introduced by Liu et al. (IEEE ITW, Sep. 2012) to close the signal-to-noise ratio (SNR) gap between LP decoding and classic belief propagation (BP) decoding. This algorithm was shown to achieve or outperform BP decoding at all SNRs, including high SNRs where BP decoding suffers from the error floor effect. In this paper, we study the behaviors of the ADMM penalized decoder at high SNRs where simulation is infeasible. We use a generic tool called instanton analysis and propose an instanton search algorithm for the ADMM penalized decoder. We then apply the algorithm to the [155, 64] Tanner code and a [1057, 813] LDPC code. We show that the instanton information we obtained provides good predictions for word-error-rate curve at high SNRs. In addition, our results suggest that the ADMM penalized decoder can suffer from trapping sets.\",\n \"Title: ADMM decoding of non-binary LDPC codes in F2m\\nYear: 2014\\n\\nAbstract: In this paper, we develop an efficient algorithm for linear programming (LP) decoding of non-binary low-density parity-check (LDPC) codes. We build our algorithm on the decomposition method based on the alternating direction method of multipliers (ADMM). Although expressing the LP decoding problem using ADMM is not hard, a sub-routine of ADMM - projection onto a polytope formed from embeddings of the non-binary single parity-check code - is not straightforward. In this work, we focus on non-binary codes in fields of characteristic two. This allows us to use operations in F2 to relax the polytope under consideration into a form that is computational friendly. We introduce a rotation step that normalizes the geometry under consideration. We then apply ADMM a second time to solve the projection problem, which is a quadratic program (QP). Our decoding algorithm scales linearly with block length, linearly with check degree, and quadratically with field size.\",\n \"Title: Achievability bounds for unequal message protection at finite block lengths\\nYear: 2014\\n\\nAbstract: We study achievability bounds for a class of unequal error protection codebooks with m > 1 different classes of codewords called unequal message protection (UMP) codes. We extend the dependence testing bound due to Polyanskiy-Poor-Verdú to be applicable to UMP codes and use this extension to obtain refined asymptotic expansions for the performance of such codes over discrete memoryless channels. In addition, we consider two questions related to the practical construction of UMP codes. First, we study a “header” construction that prefixes the message class into a header followed by data protection using a standard homogeneous (classical) code. We show that, in general, this construction is not optimal at finite block lengths. We further demonstrate that our main UMP achievability bound can be obtained using coset codes, which suggests a path to tractable implementation of UMP codes.\",\n \"Title: The Streaming-DMT of Fading Channels\\nYear: 2014\\n\\nAbstract: We consider the sequential transmission of a stream of messages over a block-fading multi-input-multi-output channel. A new message arrives at the beginning of each coherence block, and the decoder is required to output each message sequentially, after a delay of T coherence blocks. In the special case when T = 1, the setup reduces to the quasi-static fading channel. We establish the optimal diversity-multiplexing tradeoff (DMT) in the high signal-to-noise-ratio (SNR) regime, and show that it equals T times the DMT of the quasi-static channel. The converse is based on utilizing the delay constraint to amplify a local outage event associated with a message, globally across all the coherence blocks. This approach appears to be new. We propose two coding schemes that achieve the optimal DMT. The first scheme involves interleaving of messages, such that each message is transmitted across T consecutive coherence blocks. This scheme requires the knowledge of the delay constraint at both the encoder and decoder. Our second coding scheme involves a sequential tree code and is delay universal, i.e., the knowledge of the decoding delay is not required by the encoder. However, in this scheme, we require the coherence block length to increase as log (SNR), in order to attain the optimal DMT. Finally, we discuss the case when multiple messages arrive at uniform intervals within each coherence period. Through a simple example, we exhibit the suboptimality of interleaving and propose another scheme that achieves the optimal DMT.\",\n \"Title: On mismatched unequal message protection for finite block length joint source-channel coding\\nYear: 2014\\n\\nAbstract: We study the problem of lossless joint source-channel coding (JSCC) in the finite block length regime from an unequal message protection (UMP) perspective. We demonstrate that the problem of lossless JSCC can be cast in terms of UMP codes previously studied. We show that an optimal JSCC can be constructed from a matched UMP code. We further derive a finite block length bound that characterizes the performance of a JSCC constructed from a UMP code not perfectly matched to the source. This bound is evaluated for a binary memoryless source transmitted over a binary symmetric channel. Two-class schemes previously studied in literature are compared with the proposed scheme. Empirically the JSCCs based on UMP codes approach the performance of the optimal matched code quite fast in number of classes used.\",\n \"Title: A universal approach to queuing with distortion control\\nYear: 2005\\n\\nAbstract: An efficient buffer-management algorithm is developed for queues that handle distortion-tolerant data under finite memory limitations. We avoid overflows and realize significant performance gains through the use of multiresolution source codes. These codes enable us to reduce the fidelity of signal descriptions in a controlled progressive manner. The proposed approach is universal, i.e., it works without knowledge of queue arrival and departure statistics. More strongly, we show that its performance is sample-path optimal, i.e., it achieves an average distortion equal to the best achievable by any algorithm, including those designed with full noncausal knowledge of queue arrival and service times.\",\n \"Title: Boosting reliability over AWGN networks with average power constraints and noiseless feedback\\nYear: 2005\\n\\nAbstract: For the point-to-point additive white Gaussian noise (AWGN) channel with noiseless feedback and an average power constraint, Schalkwijk and Kailath's scheme achieves a doubly- exponential decay of the probability of error. While some coding schemes for networks with noiseless feedback incorporate variations on the Schalkwijk-Kailath scheme, they do not in general achieve better than single-exponential decays in their probabilities of error everywhere in their achievable rate regions. We give a technique that can boost the reliability as high as desired of any from a large class of block coding schemes for networks with feedback. The technique relies crucially on the average nature of the power constraints. We explain and illustrate our results in the context of Ozarow's feedback strategy for the AWGN multiple-access channel. I. I NTRODUCTION For the point-to-point AWGN channel with an average power constraint, Shannon (1) shows that feedback does not increase capacity. That noiseless feedback of the channel out- put is nevertheless useful for AWGN channels is shown, e.g., by Schalkwijk and Kailath (2), where they construct a simple code that achieves a doubly-exponential decay of the error probability with increasing block-length. Later, Kramer (8) analyzed a different model in which such noiseless output feedback is replaced by noiseless decision feedback, i.e., exact knowledge of what decision the decoder is about to make. Even with this weaker model, Kramer is able to show faster than doubly-exponential decay of the error probability. For AWGN networks, the situation is different in two respects. First, feedback does increase the achievable rates in many cases. Second, network reliability functions (error exponents) without feedback are mostly unknown. Indeed, many existing coding theorems for AWGN networks with feedback and average power constraints do not yield spectac- ular error exponents. Whenever typicality arguments are used, the dependence of the error probability on the block-length N becomes obscured. While there is usually an exponential term that comes from the difference of the rate and the relevant mutual information expression, there is also an term that covers the probability of the atypical set. Given the nature of the AWGN channel, in most cases we can apply a Chernoff bound and see that is also an exponentially small function of the block length. However, the exponent involved can be quite low. The situation is best illustrated by the AWGN multiple- access channel (MAC) with noiseless output feedback. Ozarow determines the full capacity region in (5), as illus-\",\n \"Title: Sequential random binning for streaming distributed source coding\\nYear: 2005\\n\\nAbstract: Random binning arguments underlie many results in information theory. In this paper we introduce and analyze a novel type of causal random binning - \\\"sequential\\\" binning. This binning is used to get stream- ing Slepian-Wolf codes with an \\\"anytime\\\" character. At the decoder, the probability of estimation error on any particular symbol goes to zero exponentially fast with delay. In the non-distributed context, we show equivalent results for fixed-rate streaming entropy coding. Because of space constraints, we present full derivations only for the latter, stating the results for the distributed problem. We give bounds on error exponents for both universal and maximum-likelihood decoders. I. I NTRODUCTION\",\n \"Title: Compound conditional source coding, Slepian-Wolf list decoding, and applications to media coding\\nYear: 2007\\n\\nAbstract: We introduce a novel source coding problem, compound conditional source coding. We describe how a number of media coding problems can be cast into this framework. We develop the achievable rate region for this problem and error exponent results. We show that the reliability function of compound conditional source coding is at least as large as the list-decoding error exponent of Slepian-Wolf coding, which we develop in addition. A message of the paper is that a number of media coding scenarios where distributed source coding techniques are being used are more exactly stated as compound conditional problems. This insight can lead to improved system performance, as we demonstrate for error exponents. IEEE International Symposium on Information Theory (ISIT)\",\n \"Title: The “hallucination” bound for the BSC\\nYear: 2008\\n\\nAbstract: Though the schemes are different, both Horstein's and Kudryashov's non-block strategies for communication with feedback over the binary-symmetric channel asymptotically achieve the identical reliability function (error exponent); a function that displays some curious features. For positive rates it is strictly larger than Burnashev's reliability function and transitions discontinuously at the channel capacity from a strictly positive value to zero. The purpose of this paper is to connect this reliability function to familiar coding contexts and to demonstrate that it provides an upper bound on the error exponents achievable in these contexts. We first show that this function gives a lower bound on the minimum probability of decoding error across codewords in a block-coding context with (or without) feedback. We then show that the same reliability function also gives an upper bound on the maximum probability of bit error in a non-block \\\"streaming\\\" context where noiseless feedback is available and the destination is (occasionally) allowed to declare erasures (per Forney). The basic insight underlying the bound leads to the moniker the \\\"hallucination\\\" bound.\",\n \"Title: Streaming data over fading wireless channels: The diversity-multiplexing tradeoff\\nYear: 2011\\n\\nAbstract: We study delay constrained sequential streaming over block fading channels. The transmitter observes a stream of messages, one message in each coherence block, and the receiver needs to output a sequence of messages, each with a fixed delay of T coherence blocks. We characterize the associated diversity-multiplexing tradeoff (DMT) for this model. The proposed coding scheme involves a semi-infinite random Gaussian tree-code and a sequential decision directed decoder. The converse applies an outage amplification argument that exploits the delay constraint to amplify the error event associated with a single message to an entire sequence of messages.\",\n \"Title: Rank minimization over finite fields\\nYear: 2011\\n\\nAbstract: This paper establishes information-theoretic limits in estimating a finite field low-rank matrix given random linear measurements of it. Necessary and sufficient conditions on the number of measurements required are provided. It is shown that these conditions are sharp. The reliability function associated to the minimum-rank decoder is also derived. Our bounds hold even in the case where the sensing matrices are sparse. Connections to rank-metric codes are discussed.\",\n \"Title: Rank Minimization Over Finite Fields: Fundamental Limits and Coding-Theoretic Interpretations\\nYear: 2012\\n\\nAbstract: This paper establishes information-theoretic limits for estimating a finite-field low-rank matrix given random linear measurements of it. These linear measurements are obtained by taking inner products of the low-rank matrix with random sensing matrices. Necessary and sufficient conditions on the number of measurements required are provided. It is shown that these conditions are sharp and the minimum-rank decoder is asymptotically optimal. The reliability function of this decoder is also derived by appealing to de Caen's lower bound on the probability of a union. The sufficient condition also holds when the sensing matrices are sparse—a scenario that may be amenable to efficient decoding. More precisely, it is shown that if the $n\\\\\\\\times n$-sensing matrices contain, on average, $\\\\\\\\Omega ({n}{\\\\\\\\log n})$ entries, the number of measurements required is the same as that when the sensing matrices are dense and contain entries drawn uniformly at random from the field. Analogies are drawn between the aforementioned results and rank-metric codes in the coding theory literature. In fact, we are also strongly motivated by understanding when minimum rank distance decoding of random rank-metric codes succeeds. To this end, we derive minimum distance properties of equiprobable and sparse rank-metric codes. These distance properties provide a precise geometric interpretation of the fact that the sparse ensemble requires as few measurements as the dense one.\",\n \"Title: Rateless Coding for Arbitrary Channel Mixtures With Decoder Channel State Information\\nYear: 2009\\n\\nAbstract: Rateless coding has recently been the focus of much practical as well as theoretical research. In this paper, rateless codes are shown to find a natural application in channels where the channel law varies unpredictably. Such unpredictability means that to ensure reliable communication block codes are limited by worst case channel variations. However, the dynamic decoding nature of rateless codes allows them to adapt opportunistically to channel variations. If the channel state selector is not malicious, but also not predictable, decoding can occur earlier, producing a rate of communication that can be much higher than the worst case. The application of rateless or ldquofountainrdquo codes to the binary erasure channel (BEC) can be understood as an application of these ideas. Further, this sort of decoding can be usefully understood as an incremental form of erasure decoding. The use of ideas of erasure decoding result in a significant increase in reliability.\",\n \"Title: Decomposition Methods for Large Scale LP Decoding\\nYear: 2012\\n\\nAbstract: When binary linear error-correcting codes are used over symmetric channels, a relaxed version of the maximum likelihood decoding problem can be stated as a linear program (LP). This LP decoder can be used to decode error-correcting codes at bit-error-rates comparable to state-of-the-art belief propagation (BP) decoders, but with significantly stronger theoretical guarantees. However, LP decoding when implemented with standard LP solvers does not easily scale to the block lengths of modern error correcting codes. In this paper, we draw on decomposition methods from optimization theory, specifically the alternating direction method of multipliers (ADMM), to develop efficient distributed algorithms for LP decoding. The key enabling technical result is a “two-slice” characterization of the parity polytope, the polytope formed by taking the convex hull of all codewords of the single parity check code. This new characterization simplifies the representation of points in the polytope. Using this simplification, we develop an efficient algorithm for Euclidean norm projection onto the parity polytope. This projection is required by the ADMM decoder and its solution allows us to use LP decoding, with all its theoretical guarantees, to decode large-scale error correcting codes efficiently. We present numerical results for LDPC codes of lengths more than 1000. The waterfall region of LP decoding is seen to initiate at a slightly higher SNR than for sum-product BP, however an error floor is not observed for LP decoding, which is not the case for BP. Our implementation of LP decoding using the ADMM executes as fast as our baseline sum-product BP decoder, is fully parallelizable, and can be seen to implement a type of message-passing with a particularly simple schedule.\",\n \"Title: Converse bounds for assorted codes in the finite blocklength regime\\nYear: 2013\\n\\nAbstract: We study converse bounds for unequal error protection codebooks with k > 1 different classes of codewords. We dub these unequal error protection codes “assorted codes”. We extend a finite blocklength converse bound due to Polyanskiy-Poor-Verdú to apply to assorted codes and use this extension to obtain a refined asymptotic expansion for the performance of assorted codes over a discrete memoryless channel. Our main contribution is to demonstrate that there is indeed a loss in the rates of an assorted code compared to equivalent homogeneous (classical) codes. Notably, when the number of codeword classes is polynomial in blocklength n the loss is apparent in the third order O(log n) term of the asymptotic expansion of the logarithm of the maximum number of codewords. This is in sharp contrast to the previous literature which only considers this problem within regimes where no such loss could be observed.\",\n \"Title: Lossless Coding for Distributed Streaming Sources\\nYear: 2014\\n\\nAbstract: Distributed source coding is traditionally viewed in a block coding context wherein all source symbols are known in advance by the encoders. However, many modern applications to which distributed source coding ideas are applied, are better modeled as having streaming data. In a streaming setting, source symbol pairs are revealed to separate encoders in real time and need to be reconstructed at the decoder with subject to some tolerable end-to-end delay. In this paper, a causal sequential random binning encoder is introduced and paired with maximum likelihood (ML) and universal decoders. The latter uses a novel weighted empirical suffix entropy decoding rule. We derive a lower bounds on the error exponent with delay for each decoder. We also provide upper bounds for the special case of streaming with decoder side information and discuss when upper and lower bounds match. We show that both ML and universal decoders achieve the same (positive) error exponents for all rate pairs inside the Slepian-Wolf achievable rate region. The dominant error events in streaming are different from those in block-coding and result in different exponents. Because the sequential random binning scheme is also universal over delays, the resulting code eventually reconstructs every source symbol correctly with probability one.\",\n \"Title: On blind compression of encrypted data approaching the source entropy rate\\nYear: 2005\\n\\nAbstract: Traditional data transmission over an insecure noiseless channel consists of rst compressing data for eciency and then encrypting it for security. Reversing the order of these operations is considered in Johnson et al. (6). The central realization is that while the raw and encrypted data are sta- tistically independent, the encrypted data and key sequence are not. If distributed source coding techniques are used to compress and to jointly decode and decrypt the data, re- versing the order need not lead to performance reductions in either communication eciency or security. In this pa- per, we build on this work by considering systems that must operate without knowledge of the underlying source statis- tics. We present and analyze an incremental scheme based on exponentially increasing block lengths that is designed to balance the resolution rate of parameter estimation with the redundancy rate of communication. We show that the re- dundancy at best declines proportional to the inverse of the square root of the block length. We implement these ideas using low-density parity check (LDPC) codes. In practical tests to transmit a binary source of 100; 000 bits, ideally com- pressible to 17; 912 bits with perfect knowledge and an ideal code, required only 26; 787 bits. In comparison, to trans- mit this source with full knowledge of the source statistics required 21; 704 bits.\",\n \"Title: The AWGN Red Alert Problem\\nYear: 2011\\n\\nAbstract: Consider the following unequal error protection scenario. One special message, dubbed the “red alert” message, is required to have an extremely small probability of missed detection. The remainder of the messages must keep their average probability of error and probability of false alarm below a certain threshold. The goal then is to design a codebook that maximizes the error exponent of the red alert message while ensuring that the average probability of error and probability of false alarm go to zero as the blocklength goes to infinity. This red alert exponent has previously been characterized for discrete memoryless channels. This paper completely characterizes the optimal red alert exponent for additive white Gaussian noise channels with block power constraints.\",\n \"Title: Cooperative reliability for streaming multiple access\\nYear: 2010\\n\\nAbstract: In this paper we bound the reliability function of decoding with errors and erasures for a streaming multiple-access channel with feedback. We show that, subject to an arbitrarily small bound on the probability of erasure, the best known lower bound on the reliability function (i.e., achievable error exponent) for the single-user version of our problem can also be achieved in the multi-user setting for high sum-rates. In other words, at high rates the interference of another user need not decrease the achievable error exponent of either.\",\n \"Title: Secure Biometrics: Concepts, Authentication Architectures, and Challenges\\nYear: 2013\\n\\nAbstract: Biometrics are an important and widely used class of methods for identity verification and access control. Biometrics are attractive because they are inherent properties of an individual. They need not be remembered like passwords and are not easily lost or forged like identifying documents. At the same time, biometrics are fundamentally noisy and irreplaceable. There are always slight variations among the measurements of a given biometric, and, unlike passwords or identification numbers, biometrics are derived from physical characteristics that cannot easily be changed. The proliferation of biometric usage raises critical privacy and security concerns that, due to the noisy nature of biometrics, cannot be addressed using standard cryptographic methods. In this article, we present an overview of secure biometrics, also referred to as biometric template protection, an emerging class of methods that address these concerns.\",\n \"Title: Proactive Message Passing on Memory Factor Networks.\\nYear: 2016\\n\\nAbstract: We introduce a new type of graphical model that we call a \\\"memory factor network\\\" (MFN). We show how to use MFNs to model the structure inherent in many types of data sets. We also introduce an associated message-passing style algorithm called \\\"proactive message passing\\\"' (PMP) that performs inference on MFNs. PMP comes with convergence guarantees and is efficient in comparison to competing algorithms such as variants of belief propagation. We specialize MFNs and PMP to a number of distinct types of data (discrete, continuous, labelled) and inference problems (interpolation, hypothesis testing), provide examples, and discuss approaches for efficient implementation.\",\n \"Title: Encoding and decoding algorithms for LP-decodable multipermutation codes\\nYear: 2015\\n\\nAbstract: LP-decodable multipermutation codes are a class of multipermutation codes that can be decoded using linear programming (LP). These codes are defined using linearly constrained multipermutation matrices, which are binary matrices that satisfy particular row sum and column sum constraints. Although generic LP solvers are capable of solving the LP decoding problem, they are not efficient in general because they do not leverage structures of the problem. This motivates us to study efficient decoding algorithms. In this paper, we focus on encoding and decoding algorithms for LP-decodable multipermutation codes. We first describe an algorithm that “ranks” multipermutations. In other words, it maps consecutive integers, one by one, to an ordered list of multipermutations. By leveraging this algorithm, we develop an encoding algorithm for a code proposed by Shieh and Tsai. Regarding decoding algorithms we propose an iterative decoding algorithm based on the alternating direction method of multipliers (ADMM), each iteration of which can be solved efficiently using off-the-shelf techniques. Finally, we study decoding performances of different decoders via simulation.\",\n \"Title: Feature transformation of biometric templates for secure biometric systems based on error correcting codes\\nYear: 2008\\n\\nAbstract: Secure storage of biometric templates is extremely important because a compromised biometric cannot be revoked and replaced an unlimited number of times. In many approaches proposed for secure biometric storage, an error correcting code (ECC) is applied to the enrollment biometric and the resulting parity or syndrome symbols are stored on the access control device, instead of the original biometric. The principal challenge here is that most standard ECCs are designed for memoryless channel statistics, whereas the variations between enrollment and probe biometrics have significant spatial correlation. To address this challenge, we propose to transform the original biometric into a feature vector that is explicitly matched to standard ECCs, thereby improving the security-robustness tradeoff of the overall biometric system. As a concrete example, we transform fingerprint minutiae maps into feature vectors compatible with ECCs designed for a binary symmetric channel. We conduct a statistical analysis of these feature vectors and show how our feature transformation algorithm may be combined with Low-Density Parity Check (LDPC) codes to obtain a secure fingerprint biometric system.\",\n \"Title: Hardware Based Projection Onto The Parity Polytope And Probability Simplex\\nYear: 2016\\n\\nAbstract: This paper is concerned with the adaptation to hardware of methods for Euclidean norm projections onto the parity polytope and probability simplex. We first refine recent efforts to develop efficient methods of projection onto the parity polytope. Our resulting algorithm can be configured to have either average computational complexity O(d) or worst case complexity O(d log d) on a serial processor where d is the dimension of projection space. We show how to adapt our projection routine to hardware. Our projection method uses a sub-routine that involves another Euclidean projection; onto the probability simplex. We therefore explain how to adapt to hardware a well know simplex projection algorithm. The hardware implementations of both projection algorithms achieve area scalings of O(d (log d)(2)) at a delay of O((log d)(2)). Finally, we present numerical results in which we evaluate the fixed-point accuracy and resource scaling of these algorithms when targeting a modern FPGA.\",\n \"Title: Hardware-Based ADMM-LP Decoding.\\nYear: 2016\\n\\nAbstract: In this paper we present an FPGA-based implementation of linear programming (LP) decoding. LP decoding frames error correction as an optimization problem. This is in contrast to variants of belief propagation (BP) decoding that view error correction as a problem of graphical inference. There are many advantages to taking the optimization perspective: convergence guarantees, improved performance in certain regimes, and a methodology for incorporating the latest developments in optimization techniques. However, LP decoding, when implemented with standard LP solvers, does not easily scale to the blocklengths of modern error-correction codes. In earlier work, we showed that by drawing on decomposition methods from optimization theory, specifically the alternating direction method of multipliers (ADMM), we could build an LP decoding solver that was competitive with BP, both in terms of performance and speed. We also observed empirically that LP decoders have much better high-SNR performance in the \\\"error floor\\\" regime, a trait of particular relevance to optical transport and storage applications. While our previous implementation was in floating point, in this paper we report initial results of a fixed-point, hardware-based realization of our ADMM-LP decoder.\",\n \"Title: Hardware-Based Linear Program Decoding with the Alternating Direction Method of Multipliers.\\nYear: 2016\\n\\nAbstract: We present a hardware-based implementation of linear program (LP) decoding for binary linear codes. LP decoding frames error-correction as an optimization problem. In contrast, variants of belief propagation (BP) decoding frame error-correction as a problem of graphical inference. LP decoding has several advantages over BP-based methods, including convergence guarantees and better error-rate perfo...\",\n \"Title: Anytime coding for distributed computation.\\nYear: 2016\\n\\nAbstract: novel coding scheme is proposed to speed up distributed computation through a form of approximate computing. It is known that task replication can greatly mitigate the \\\"straggler effect\\\" in cloud computing, wherein an overall computation can be significantly delayed by slowed processing nodes (or \\\"stragglers\\\"). It has also been demonstrated that, in certain contexts, ideas of error-correction coding can more efficiently deal with stragglers than pure replication. The approach proposed herein builds on these earlier observations through an \\\"anytime\\\" approach to approximate computing. In this paradigm, over time one can produces approximate solutions of increasing accuracy. To accomplish this we first decompose a computational job in to tasks of various priorities. Next, we apply linear error correction coding to produce subtasks that are assigned to different processors. The decomposition used has a big effect on the type of anytime performance we attain. We study this scheme in a general framework in terms of the expected cost of the approximate solution. We further explore the approach in the context of vector-matrix multiplication. The proposed construction is numerically studied and, in comparison to previous work, demonstrates a significant improvement in the accuracy/latency trade-off.\",\n \"Title: Bit-Interleaved Polar-Coded Ofdm For Low-Latency M2m Wireless Communications\\nYear: 2017\\n\\nAbstract: Machine-to-machine (M2M) communications play an important role for applications that involve connections between a massive number of heterogeneous devices in home and industrial networks. For M2M networks, realizing low latency and high reliability is of great importance. In this paper, we show the great potential of polar-coded orthogonal frequency-division multiplexing (OFDM) to fulfill those requirements. We show that polar codes with list decoding plus cyclic redundancy check (CRC) can outperform state-of-the-art low-density parity-check (LDPC) codes at short block lengths. In addition, we introduce an efficient interleaver and constellation shaping for polar-coded high-order modulations, where a coded sequence is carefully mapped across subcarriers and modulation bits to exploit non-uniform reliability for higher diversity gains. Through computer simulations, we demonstrate that a significant gain greater than 2 dB can be achieved by quadratic polynomial permutation (QPP) interleaver with optimized parameters in comparison to the conventional random interleaver for high-order 256-ary quadrature-amplitude modulation (QAM) OFDM transmission in frequency-selective wireless channels.\",\n \"Title: Fast Power and Energy Management for Future Many-Core Systems.\\nYear: 2017\\n\\nAbstract: Future servers will incorporate many active low-power modes for each core and for the main memory subsystem. Though these modes provide flexibility for power and/or energy management via Dynamic Voltage and Frequency Scaling (DVFS), prior work has shown that they must be managed in a coordinated manner. This requirement creates a combinatorial space of possible power mode configurations. As a result, it becomes increasingly challenging to quickly select the configuration that optimizes for both performance and power/energy efficiency.\\n\\nIn this article, we propose a novel queuing model for working with the abundant active low-power modes in many-core systems. Based on the queuing model, we derive two fast algorithms that optimize for performance and efficiency using both CPU and memory DVFS. Our first algorithm, called FastCap, maximizes the performance of applications under a full-system power cap, while promoting fairness across applications. Our second algorithm, called FastEnergy, maximizes the full-system energy savings under predefined application performance loss bounds. Both FastCap and FastEnergy operate online and efficiently, using a small set of performance counters as input. To evaluate them, we simulate both algorithms for a many-core server running different types of workloads. Our results show that FastCap achieves better application performance and fairness than prior power capping techniques for the same power budget, whereas FastEnergy conserves more energy than prior energy management techniques for the same performance constraint. FastCap and FastEnergy together demonstrate the applicability of the queuing model for managing the abundant active low-power modes in many-core systems.\",\n \"Title: Anytime Exploitation of Stragglers in Synchronous Stochastic Gradient Descent\\nYear: 2017\\n\\nAbstract: In this paper we propose an approach to parallelizing synchronous stochastic gradient descent (SGD) that we term “Anytime-Gradients”. The Anytime-Gradients is designed to exploit the work completed by slow compute nodes or “stragglers”. In many approaches work completed by these nodes, while only partial, is discarded completely. To maintain synchronization in our approach, each computational epoch is of fixed duration, and at the end of each epoch, workers send updated parameter vectors to a master mode for combination. The master weights each update by the amount of work done. The Anytime-Gradients scheme is robust to both persistent and non-persistent stragglers and requires no prior knowledge about processor abilities. We show that the scheme effectively exploits stragglers and outperforms existing methods.\",\n \"Title: Irregular Polar Coding for Massive MIMO Channels.\\nYear: 2017\\n\\nAbstract: Recent advancements in polar coding have achieved practical performance competitive with other capacity-achieving codes such as low-density parity-check codes. In this paper, we propose a new family called irregular polar codes, where polarlization units are irregularly inactivated to achieve additional degrees of freedom for code design. We first discuss the code construction for irregular polar-coded modulation by taking non-uniform bit-reliability into consideration. We then apply the proposed polar codes to wireless massive multiple-input multiple-output (MIMO) communication channels. Simulation results show that the irregular polar codes can significantly reduce encoding/decoding complexity up to 50% while also yielding a marginal improvement in error rate performance.\",\n \"Title: Exploitation Of Stragglers In Coded Computation\\nYear: 2018\\n\\nAbstract: In cloud computing systems slow processing nodes, often referred to as \\\"stragglers\\\", can significantly extend the computation time. Recent results have shown that error correction coding can be used to reduce the effect of stragglers. In this work we introduce a scheme that, in addition to using error correction to distribute mixed jobs across nodes, is also able to exploit the work completed by all nodes, including stragglers. We first consider vector-matrix multiplication and apply maximum distance separable (MDS) codes to small blocks of sub-matrices. The worker nodes process blocks sequentially, working block-by-block, transmitting partial per-block results to the master as they are completed. Sub-blocking allows a more continuous completion process, which thereby allows us to exploit the work of a much broader spectrum of processors and reduces computation time. We then apply this technique to matrix-matrix multiplication using product code. In this case, we show that the order of computing sub-tasks is a new degree of design freedom that can be exploited to reduce computation time further. We propose a novel approach to analyze the finishing time, which is different from typical order statistics. Simulation results show that the expected computation time decreases by a factor of at least two in compared to previous methods.\",\n \"Title: Hierarchical Coded Computation\\nYear: 2018\\n\\nAbstract: Coded computation is a method to mitigate \\\"stragglers\\\" in distributed computing systems through the use of error correction coding that has lately received significant attention. First used in vector-matrix multiplication, the range of application was later extended to include matrix-matrix multiplication, heterogeneous networks, convolution, and approximate computing. A drawback to previous results is they completely ignore work completed by stragglers. While stragglers are slower compute nodes, in many settings the amount of work completed by stragglers can be non-negligible. Thus, in this work, we propose a hierarchical coded computation method that exploits the work completed by all compute nodes. We partition each node's computation into layers of sub-computations such that each layer can be treated as (distinct) erasure channel. We then design different erasure codes for each layer so that all layers have the same failure exponent. We propose design guidelines to optimize parameters of such codes. Numerical results show the proposed scheme has an improvement of a factor of 1.5 in the expected finishing time compared to previous work.\",\n \"Title: Efficient learning of neighbor representations for boundary trees and forests.\\nYear: 2018\\n\\nAbstract: We introduce a semiparametric approach to neighbor-based classification. We build off the recently proposed Boundary Trees algorithm by Mathy et al. (2015) which enables fast neighbor-based classification, regression and retrieval in large datasets. While boundary trees use an Euclidean measure of similarity, the Differentiable Boundary Tree algorithm by Zoran et al. (2017) was introduced to learn low-dimensional representations of complex input data, on which semantic similarity can be calculated to train boundary trees. As is pointed out by its authors, the differentiable boundary tree approach contains a few limitations that prevents it from scaling to large datasets. In this paper, we introduce Differentiable Boundary Sets, an algorithm that overcomes the computational issues of the differentiable boundary tree scheme and also improves its classification accuracy and data representability. Our algorithm is efficiently implementable with existing tools and offers a significant reduction in training time. We test and compare the algorithms on the well known MNIST handwritten digits dataset and the newer Fashion-MNIST dataset by Xiao et al. (2017).\",\n \"Title: Anytime Stochastic Gradient Descent: A Time to Hear from all the Workers.\\nYear: 2018\\n\\nAbstract: In this paper, we focus on approaches to parallelizing stochastic gradient descent (SGD) wherein data is farmed out to a set of workers, the results of which, after a number of updates, are then combined at a central master node. Although such synchronized SGD approaches parallelize well in idealized computing environments, they often fail to realize their promised computational acceleration in practical settings. One cause is slow workers, termed stragglers, who can cause the fusion step at the master node to stall, which greatly slowing convergence. In many straggler mitigation approaches work completed by these nodes, while only partial, is discarded completely. In this paper, we propose an approach to parallelizing synchronous SGD that exploits the work completed by all workers. The central idea is to fix the computation time of each worker and then to combine distinct contributions of all workers. We provide a convergence analysis and optimize the combination function. Our numerical results demonstrate an improvement of several factors of magnitude in comparison to existing methods.\",\n \"Title: Introduction to the Issue on Information-Theoretic Methods in Data Acquisition, Analysis, and Processing.\\nYear: 2018\\n\\nAbstract: The twenty papers that are included in this special section explore applications of information theoretic methods to emerging data science problems. In particular, the papers cover a wide range of topics that can broadly be organized into four themes: (1) data acquisition, (2) data analysis and processing, (3) statistics and machine learning, and (4) privacy and fairness.\",\n \"Title: Bit-Interleaved Polar-Coded Modulation For Low-Latency Short-Block Transmission\\nYear: 2017\\n\\nAbstract: We show that polar codes with list+CRC decoding can outperform state-of-the-art LDPC codes in short block lengths. In addition, we introduce an efficient interleaver for polar-coded high-order modulations, achieving greater than 0.5 dB gain for 256QAM.\",\n \"Title: Irregular Polar Coding for Multi-Level Modulation in Complexity-Constrained Lightwave Systems\\nYear: 2017\\n\\nAbstract: We introduce novel irregular polar codes, which extend the regular polar coding by flexible polarization pruning. We experimentally demonstrate that the proposed polar codes outperform state-of-the-art LDPC codes, while the computational complexity in encoding and decoding can be significantly reduced by at least 30% over the regular polar codes with a marginal performance improvement.\",\n \"Title: Anytime Minibatch with Stale Gradients : (Invited Paper)\\nYear: 2019\\n\\nAbstract: Large-scale machine learning problems are often solved using distributed optimization techniques by dividing tasks across multiple compute nodes. Due to variability in compute time amongst nodes, distributed systems suffer from slow nodes known as stragglers that can have a big impact on convergence speed. Recently, Anytime Minibatch (AMB) technique has been proposed to speed up convergence by exploiting work done by stragglers rather than avoiding them. In AMB, workers are given a fixed time to calculate gradients, followed by a fixed communication time to average gradients. We observe that nodes stay idle during communication time. In our work, we allow workers to compute gradients during communication time resulting in what is known as stale gradients due to gradients calculated on out-of-date parameters. Our simulation results show that such approach achieves up to 60% faster convergence in wall time.\",\n \"Title: Compressing Gradients by Exploiting Temporal Correlation in Momentum-SGD\\nYear: 2021\\n\\nAbstract: An increasing bottleneck in decentralized optimization is communication. Bigger models and growing datasets mean that decentralization of computation is important and that the amount of information exchanged is quickly growing. While compression techniques have been introduced to cope with the latter, none has considered leveraging the temporal correlations that exist in consecutive vector updates...\",\n \"Title: Asynchronous Delayed Optimization With Time-Varying Minibatches\\nYear: 2021\\n\\nAbstract: Large-scale learning and optimization problems are often solved in parallel. In a master-worker distributed setup, worker nodes are most often assigned fixed-sized minibatches of data points to process. However, workers may take different amounts of time to complete their per-batch calculations. To deal with such variability in processing times, an alternative approach has recently been proposed w...\",\n \"Title: HIERARCHICAL CODED ELASTIC COMPUTING\\nYear: 2021\\n\\nAbstract: Elasticity is offered by cloud service providers to exploit under-utilized computing resources. The low-cost elastic nodes can leave and join any time during the computation cycle. The possibility of elastic events occurring together with the problem of slow nodes, referred to as stragglers, increases the uncertainty of the system, leading to computation delay. Recent results have shown that coded computing can be used to reduce the negative effect of elasticity and stragglers. In this paper, we propose two hierarchical coded elastic computing schemes that can further speed up the system by exploiting stragglers and effectively allocating tasks among available nodes. In our simulations, our scheme realizes 45% improvement in average finishing time compared to the state-of-the-art coded elastic computing scheme.\",\n \"Title: Probabilistic Shaping Using a Block-Based Bit-Level Distribution Matcher\\nYear: 2022\\n\\nAbstract: We present a distribution matching architecture aimed at low-complexity probabilistic shaping. The scheme oper-ates by combining blocks of bits, generated in parallel by multiple binary distribution matchers, and mapping them to blocks of symbols from a non-binary alphabet. The proposed architecture constitutes a block-based generalization of the bit-level distribution matching (BL-DM) method. Namely, BL-DM corresponds to the particular case wherein single-bit blocks are used. While the computational complexity of our proposed scheme is effectively independent of the block size, larger block sizes can be used to realize a wider range of shaped output distributions, and in turn lead to an improved shaping performance. We demonstrate this benefit in our numerical simulations, which show that by using an increasingly larger block size, a lower per-shaped-symbol energy can be realized across all shaping rates and output blocklengths.\",\n \"Title: SAPA: Sparse Affine Projection Algorithm in ADMM-LP Decoding of LDPC Codes\\nYear: 2022\\n\\nAbstract: We present a simplified alternating direction method of multipliers with linear programming (ADMM-LP) decoder for LDPC codes by developing a method of approximate projection onto the parity polytope. The algorithm projects onto the affine hull of the \\n<tex xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">$X$</tex>\\n closest local codewords for each check of degree d, where \\n<tex xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">$X$</tex>\\n can be much smaller than d. We name this SAPA, the “sparse affine projection algorithm”. In contrast to exact projection, SAPA does not require a water-filling step and thus can be implemented with lower per-iteration complexity. We present numerical results which demonstrate not only that SAPA's performance, when used as part of an overall decoder, is close to that of exact projection, but also that the use of SAPA does not incur many additional iterations. This is in contrast to other approximate algorithms. Thus, SAPA is appropriate for use in limited-iteration decoders in high-throughput applications. Moreover, we analyze sparsity of polytope projections in the exact ADMM-LP decoding to explain the suitability of the proposed sparse approximation.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":84,"string":"84"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":44,"string":"44"}}},{"rowIdx":45,"cells":{"question_id":{"kind":"string","value":"Agostino Poggi"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Quantitative Assessment of the JADEL Programming Language.\" using the following items: JADEL, agent-oriented programming language, effectiveness, concurrency, metrics."},"answer":{"kind":"string","value":"This paper reports a quantitative assessment of JADEL, an agent-oriented programming language designed to implement JADE agents and multi-agent systems. The assessment is structured in two parts. The first part is intended to evaluate the effectiveness of JADEL for the concrete implementation of agent-based algorithms expressed using a pseudocode. The second part examines the functionality of the language regarding concurrency and message passing by comparing the implementation in JADEL of a set of benchmark algorithms with the corresponding implementations in Scala. The metrics introduced for the two parts of the assessment are meant to evaluate the expressiveness and ease of use of JADEL, and reported results are encouraging."},"correct_answer":{"kind":"string","value":"This paper reports a quantitative assessment of JADEL, an agent-oriented programming language designed to implement JADE agents and multi-agent systems. The assessment is structured in two parts. The first part is intended to evaluate the effectiveness of JADEL for the concrete implementation of agent-based algorithms expressed using a pseudocode. The second part examines the functionality of the language regarding concurrency and message passing by comparing the implementation in JADEL of a set of benchmark algorithms with the corresponding implementations in Scala. The metrics introduced for the two parts of the assessment are meant to evaluate the expressiveness and ease of use of JADEL, and reported results are encouraging."},"documents":{"kind":"list like","value":["Title: Modeling Deployment and Mobility Issues in Multiagent Systems Using AUML\nYear: 2003\n\nAbstract: This paper demonstrates how UML can be exploited and extended to model the deployment of a multiagent system at the agent level. This is accomplished by extending the formally-based UML 2.0 metamodel to support the semantics of agents, mobile agents and their supporting platforms. Additionally, the UML-based notation, used to model the deployment of a multiagent system, takes advantage of stereotypes to associate an agent-oriented semantics with the model elements used in the diagram. A primary objective of this paper is to demonstrate that the Agent UML (AUML) deployment diagram can be successfully applied to real-world applications. This AUML work is organized as an activity within the FIPA Modeling Technical Committee.","Title: A Two-Level Approach for Ontology Management in Multi-Agent Systems\nYear: 2005\n\nAbstract: This paper addresses the need for strong security guarantees in increasingly dynamic and flexible information technology (IT) environments. It applies time-tested security principles, architectural patterns, and continuous improvement constructs to weave ...","Title: Extending JADE for Agent Grid Applications\nYear: 2004\n\nAbstract: This paper presents an extension of the JADE agent development framework that may be the basis for the realization of flexible agent-based grid systems. In particular, JADE framework has been enriched with two new types of agents that, on the one hand simplify the distribution of tasks inside a grid of agent platforms, and, on the other hand, facilitate the composition of tasks through the use of production rules. Moreover, the paper describes how such kinds of operations are executed through the proper authentication and authorization mechanisms.","Title: Supporting Social Networks With Agent-Based Services\nYear: 2013\n\nAbstract: Current approaches to build social networking systems are based on a centralized architecture because it allows a simple browser-based user experience and makes easier and more efficient to implement many algorithms used in a social networking site e.g., friend suggestion, However this kind of architecture has many drawbacks for its users, e.g., lack of privacy, lack of anonymity, risks of censorship and operating costs. This paper presents a system, called Blogracy, which uses widespread and stable peer-to-peer technologies, such as distributed hash tables and BitTorrent, for coping with intrinsic defects of centralized architectures and for being the basis of solid distributed social networking platforms. Moreover, Blogracy takes advantages of multi-agent systems for simplifying the implementation of social network services in a decentralized setting.","Title: A Development Environment for the Realization of Open and Scalable Multi-agent Systems\nYear: 1999\n\nAbstract: This paper presents a development environment suitable for the design and implementation of multi-agent systems. This environment is designed following the guidelines found in HPA specifications. Therefore, it offers the management agents and services necessary to realize a RPA-compliant open system. An agent prototype is also provided in order to ease the implementation of domain-specific agents. Even if the development environment mainly supports the C++ language, the resulting architectures are heavily based on the concept of roaming agent through a distributed environment. Interoperability with other systems, supporting other languages such as Java, is guaranteed by FIPA specifications. The presented environment has been used to develop a multi-agent system that should integrate the different software modules performing sensory data interpretation, planning and faults diagnosis of a robot working in a space station.","Title: An agent model platform for realizing efficient and reusable agent software\nYear: 2000\n\nAbstract: In this paper, we present an agent model and platform we defined and implemented to realize efficient and reusable agent software through an agent development environment called JADE. JADE (Java Agent Development Environment) is a software framework to make easy the development of agent applications in compliance with the FIPA specifications for interoperable intelligent multi-agent systems. 1. JADE AGENT PLATFORM The JADE Agent Platform complies with the FIPA specifications [2] and includes all those mandatory agents that manage the platform, that is the ACC, the AMS, and the DF. Agent communication is performed through message passing, where FIPA ACL is the language to represent messages. JADE communication architecture tries to offer flexible and efficient messaging, transparently choosing the best transport a'¢ailable and leveraging state-of-the-art distributed object technology embedded within Java runtime environment. While appearing as a single entity to the outside world, a JADE agent platform is itself a distributed system, since it can be split over several hosts with one among them acting as a front end for interplatform IIOP communication. A JADE system is made by one or more Agent Container, each one living in a separate Java Virtual Machine and deiivering runtime environment support to JADE agents. Java RMI is used to communicate among the containers and each one of them can also act as an IIOP client to forward outgoing messages to foreign agent platforms. A special, Front End container is also an IIOP server, listening at the official agent platform ACC address for incoming messages from other platforms. The two mandatory system agents, that is the AMS and the default DF, run within the front-end container.","Title: Ontology-Based Remote Collaboration for the Development of Software System\nYear: 2005\n\nAbstract: RAP (Remote Assistant for Programmers) is a Web and multi-agent based system to support remote students and programmers during common pro- jects or activities based on the Java programming language. RAP helps users to solve problems proposing information extracted from dedicated repositories and forwarding answers received from other users, recommended as experts. Its peculiar characteristic is the integration of the agent technology with the seman- tic Web technology. In fact, in order to improve filtering and recommendation techniques, RAP takes advantage of an ontological approach to user and docu- ment profiling. A RAP system is not a closed system, instead it is based on a dynamic network of RAP platforms managing groups of geographically local- ized users and documents. Therefore, recommendations should take into ac- count of the accessible experts and documents. At this purpose, RAP users and documents profile management subsystems provide a mechanism that dynami- cally adapts the relevance of each profile. An initial prototype of the RAP Sys- tem is under development by using JADE.","Title: Attribute grammars as a robust technical basis for a human-computer interaction general purpose architecture\nYear: 1997\n\nAbstract: In this paper, we present a Natural Language Interface (NLI) that combines some of the advantages of using general purpose grammars with some of the features found in semantic grammars. This is achieved by an Attribute Grammar so as to create an intermediate representation which is interpreted in terms of domain-specific routines. NLI has been used as a component of a Human–Computer Interaction (HCI) system, working on different domains. After a discussion of the theory underlying the system, two examples of the use of NLI on practical domains are described: the first is in the field of three-dimensional scene generation, the second in the field of road map car planning. Some evaluation issues are also included in this paper.","Title: Enabling FIPA Agents on Small Devices\nYear: 2001\n\nAbstract: The foreseen progress of the market of portable devices is demanding the realisation of increasingly complex applications for increasingly smaller and ubiquitous devices. This trend promotes the migration of technologies that were originally developed for desktop computers to mobile devices. This paper describes the current results of the LEAP project, a European-scale effort that aims at enabling FIPA agents on small devices. The LEAP project achieves its goal providing a FIPA-compliant agent platform that runs seamlessly on any Java-enabled device, from cellular phones to enterprise servers. This platform is naturally ubiquitous as it can be configured to run on any mobile or fixed device. The LEAP project has already released a first version of the platform to registered users for testing purposes and the second, and final, version will be released in open source by the end of this year. We tested the platform in a logistics scenario intended to provide mobile workers with \"just-in-time information.\"","Title: A Collaborative and Multi-Agent Approach to E-mail Filtering\nYear: 2005\n\nAbstract: CAFE (Collaborative Agents for Filtering E-mails) is a multi-agent system to collaboratively filter spam from usersý mail. CAFE associates each user with a proxy agent that acts as an interface between the userýs e-mail client and the server. With the support of other agents, the proxy agent classifies messages into three categories: ham (good messages), spam and spam-presumed. The system analyzes each message using three approaches: the first is based on an hash function, the second (static) on DNSBL (DNS-based Black Lists) databases and the third (dynamic) on a Bayesian filter. We give a mathematical representation of the system, showing that if the users collaborate, the fault probability decreases in proportion to the number of active users.","Title: DAISY: an object-oriented system for Distributed Artificial Intelligence\nYear: 1994\n\nAbstract: This paper presents an object-oriented distributed system, called DAISY, for the development and experimentation of Distributed Artificial Intelligence systems and algorithms. This system is based on two programming levels: object level and agent level. Both the levels allow to define, implement and experiment systems. While the object level offers a large set of low level programming means (a large set of program constructs, a set of low level communication procedures, and so on), the agent level, which is implemented on the object level, offers a limited set of high level programming means (few program constructs, a fixed set of high level communication procedures derived by speech act theory and a fixed set of high level procedures to manage agent's knowledge). In particular, the paper shows the use of DAISY for modeling an airline reservation scenario and a manufacturing plant scenario.","Title: Deploying FIPA-Compliant Systems on Handheld Devices\nYear: 2001\n\nAbstract: LEAP is a runtime environment for deploying agents on a network of Java-enabled devices. It complies with FIPA international standards for multiagent systems.","Title: Supporting Agent-Oriented Modelling With Uml\nYear: 2002\n\nAbstract: Software engineering relies on the possibility of describing a system at different levels of abstraction. Agent-oriented software engineering introduces a new level of abstraction, that we called agent level, to allow the architect modelling a system in terms of interacting agents. This level of abstraction is not supported by an accepted set of tools and notations yet, even if a number of proposals are available. This paper introduces: (i) An UML-based notation capable of modelling a system at the agent level and (ii) A development framework, called ParADE, exploiting such a notation. The notation we propose is formalized in terms of a UML profile and it supports the realisation of artefacts modelling two basic concepts of the agent level, i.e., the architecture of the multi-agent system and the ontology followed by agents. The choice of formalising our notation in terms of a UML profile allows using it with any off-the-shelf CASE tool. The ParADE framework takes advantage of this choice by providing a code generator capable of producing skeletons of FIPA-compliant agents from XMI files of agent-oriented models. The developer is requested to complete the generated skeletons exploiting the services that ParADE and the underlying agent platform provide.","Title: Agent-Based support for open communities\nYear: 2005\n\nAbstract: RAVE (Remote Assistance Virtual Environment) is a Web and multi-agent based system to support remote users during common projects or activities. A Personal Agent, associated with a specific user, helps her/him to solve problems proposing information and answers extracted from some information repositories. It's also able to forward answers received from other on-line users, recommended by their Personal Agents as experts in that specific topic. A profile is built and maintained for each user. A RAVE system is not a closed system, but it's based on a dynamic network of RAVE platforms managing groups of geographically localized users and documents. RAVE users and documents profile management subsystems provide a mechanism that dynamically adapts the relevance of each profile, according to the availability of experts and documents.","Title: Service Composition in Open Agent Societies\nYear: 2003\n\nAbstract: Agentcities is a network of FIPA compliant agent platforms that constitute a distributed environment to demonstrate the potential of autonomous agents. One of t he aims of the project is the development of a network ar chitecture to allow the integration of platforms based on different technologies and models. It provides basic white pages an d yellow pages services to allow the dynamic discovery of the hosted agents and the services they offer. An important outcome is the exploitation of the capability of agent-based applic ations to adapt to rapidly evolving environments. This is parti cularly appropriate to dynamic societies where agents act as buyer s and sellers negotiating their goods and services, and composi ng simple services offered by different providers into new compound services.","Title: Multi-Agent Corporate Memory Management System\nYear: 2002\n\nAbstract: This paper presents an approach to design a multi-agent system managing a corporate memory in the form of a distributed semantic Web and describes the resulting architecture. The system was designed during the CoMMA European project ( Corporate Memory Management through Agents) and aims at helping users in the management of a corporate memory, facilitating the creation, dissemination, transmission, and reuse of knowledge in an organization. The implementation integrated several emerging technologies: multi-agent system technology ( using the JADE FIPA-compliant platform), knowledge modeling and XML technology for information retrieval ( using the CORESE semantic search engine), and machine learning techniques. Here, we describe the agent roles and interactions, we explain the design rationale for the agent societies, and we discuss the configuration and implementation issues.","Title: CAFE - collaborative agents for filtering e-mails\nYear: 2005\n\nAbstract: CAFE (collaborative agents for filtering e-mails) is a multiagent system to collaboratively filter spam from users' mail stream. CAFE associates a proxy agent with each user, and this agent represents a sort of interface between the user's e-mail client (i.e. Microsoft Outlook, Eudora, etc.) and the e-mail server. With the support of other types of agents, the proxy agent makes a classification of new messages into three categories: ham (good messages), spam and spam-presumed. The system analyzes every single e-mail using essentially three kinds of approach: a first approach based on the usage of a hash function, a static approach using DNSBL (DNS-based black lists) databases and a dynamic approach based on a Bayesian algorithm.","Title: Agent-Based Virtual Communities for Interactive Digital Television\nYear: 2006\n\nAbstract: This paper describes a multi-agent framework designed to support the creation and effective management of virtual communities in an Interactive Digital Television (IDTV) scenario. The possibiliti es that this framework offers are demonstrated by mean s of two sample applications: a real-time community game and an asynchronous auction. For the sake of completeness, the paper also presents an overview o f IDTV technologies.","Title: Intelligent Task Composition and Allocation through Agents\nYear: 2005\n\nAbstract: This paper addresses the need for strong security guarantees in increasingly dynamic and flexible information technology (IT) environments. It applies time-tested security principles, architectural patterns, and continuous improvement constructs to weave ...","Title: Developing multi-agent systems with a FIPA-compliant agent framework\nYear: 2001\n\nAbstract: To ease large-scale realization of agent applications there is an urgent need for frameworks, methodologies and toolkits that support the effective development of agent systems. Moreover, since one of the main tasks for which agent systems were invented is the integration between heterogeneous software, independently developed agents should be able to interact successfully. In this paper, we present JADE (Java Agent Development Environment), a software framework to build agent systems for the management of networked information resources in compliance with the FIPA specifications for inter-operable intelligent multi-agent systems. The goal of JADE is to simplify development while ensuring standard compliance through a comprehensive set of system services and agents, JADE can then be considered to be an agent middle-ware that implements an efficient agent platform and supports the development of multi-agent systems. It deals with all the aspects that are not peculiar to agent internals and that are independent of the applications, such as message transport, encoding and parsing, or agent life-cycle management. Copyright (C) 2001 John Wiley & Sons, Ltd.","Title: Enhancing peer-to-peer applications with multi-agent systems\nYear: 2008\n\nAbstract: This paper copes with the problem of integrating peer-to-peer and multi-agent systems for the realization of both large-scale multi-agent systems and sophisticated peer-to-peer applications. In particular, it presents how JADE, one of the best known and most used software framework for the development of multi-agent systems, has been extended with a peer-to-peer technology, and how a JADE multi-agent system can be overlapped over a peer-to-peer system to provide more sophisticated services.","Title: Cooperative software agents for the Unix domain\nYear: 1996\n\nAbstract: The paper presents an agent architecture that integrates multiple capabilities into a single intelligent agent allowing it to interact both with other agents through an expressive agent communications language and with humans through a human agent interface, and to satisfy external requests either through the direct execution of a set of actions or through a plan defined by an internal planner. This agent architecture has been implemented using a programming environment which takes advantage of object-oriented programming features, and has been experimented with in the Unix domain specializing it to define an agent able to perform a set of Unix commands and to execute actions in cooperation with other agents.","Title: Exploiting UML in the Design of Multi-agent Systems\nYear: 2000\n\nAbstract: A basic concept of software engineering is that a system can be described at different levels of abstraction. Agent-oriented software engineering introduces a new level of abstraction, called the agent level, to allow software architects modelling a system in terms of interacting agents. This level of abstraction is not yet supported by an accepted diagrammatic notation even if a number of proposals are available. This work shows how UML can be exploited to model a multi-agent system at the agent level. In particular, it presents a set of agent-oriented diagrams intended to provide an UML-based notation to model: the architecture of the multi-agent system, the ontology followed by agents and the interaction protocols used to co-ordinate agents. The presented notation exploits stereotypes to associate an agent-oriented semantic with class and collaboration diagrams. The benefit of using stereotypes rather than extending UML to provide an agent-oriented semantic is that the presented notation can be used with any off-the-shelf CASE tool.","Title: Enhancing information sharing through agents\nYear: 2006\n\nAbstract: This paper presents RAIS, a peer-to-peer multi-agent system for information sharing among a community of users connected through the Internet. RAIS offers a similar search power of Web search engines, but avoids the burden of publishing information on the Web and guarantees a controlled and dynamic access to information. The use of agent technologies has made straightforward the realization of three of the main features of the system: i) filtering of information coming from different users, on the basis of the previous experience of the local user, ii) pushing of new information that can be of interest for a user, and iii) delegation of access capabilities, on the basis of a reputation network, built by the agents of the system on the community of its users.","Title: Security and Trust in Agent-Oriented Middleware\nYear: 2003\n\nAbstract: Spreading of technologies as peer-to-peer networks, web services, multi-agent systems, ubiquitous computing, shows a clear trend toward open and highly distributed systems, requiring wide and dynamic overlay networks. But mass adoption of these technologies, especially in contexts where sensible resources are handled, will come true only if they will be able to guarantee a proper level of security. This paper presents the implementation of a security layer for JADE, a standard-based and widely deployed framework to build multi-agent systems. The proposed model, founded on delegation certificates, allows the management of trust relations among autonomous software agents collaborating and competing in wide and open agent societies, but it is also used to protect the underlying distributed infrastructure, providing required resources and services to hosted agents. Our approach, where policies are based on keys instead of names, enhances robustness and scalability by greatly reducing the impact of certificate directory unavailability on the authorization mechanism.","Title: A Contract Decommitment Protocol for Automated Negotiation in Time Variant Environments\nYear: 2001\n\nAbstract: Negotiation is a fundamental mechanism in distributed multi-agent systems. Since negotiation is a time-spending process, in many scenarios agents have to take into account the passage of time and to react to uncertain events. The possibility to decommit from a contract is considered a powerful technique to manage this aspect. This paper considers interactions among self-interested and autonomous agent, each with their own utility function, and focuses on incomplete information. We define a negotiation model based on asynchronous message passing in which the negotiation doesn't end when an agreement is reached but when the consequences of the contract have happened - i.e. the action is done. In this model the agent utility functions are time dependent. We present an extension of the contract net protocol that implements the model.","Title: Developing Smart Emergency Applications with Multi-Agent Systems\nYear: 2010\n\nAbstract: Multi-agent systems have been importantly contributing to the development of the theory and the practice of complex distributed systems and, in particular, they have shown their potential to meet critical needs in high-speed, mission-critical, content-rich, distributed information applications where mutual interdependencies, dynamic environments, uncertainty, and sophisticated control play a remarkable role. Therefore, multi-agent systems are considered a suitable technology for the realization of e-health applications where the use of loosely coupled and heterogeneous components, the dynamic and distributed management of data, and the remote collaboration among users are often the most relevant requirements. This paper describes some of the main reasons why multi-agent systems are today considered one of the best technologies for the realization and deployment of advances for e-health applications and, in particular, of smart emergency applications. After an introduction on the inherent characteristics of the use of multi-agent systems for e-health, the paper presents the results of EU-scale project CASCOM: a real multi-agent system for the execution of smart emergency tasks.","Title: A Portal for Ubiquitous Collaboration\nYear: 2003\n\nAbstract: This paper presents a software framework, called Collaborator, to provide a shared work-space supporting the activities of virtual teams. This sys- tem exploits seamless integration of standar d Web technologies with agent technologies, enhancing the classic Web communication mechanisms to su p- port synchronous sharing of applic ations, and its use through emerging tech- nologies such as: third generation of mobile networks and terminals, and new generation of home appliances. The system presented in the paper is the main result of an on-going European research project Collaborator (IST-2000-30045) that aims at specifying and developing a software distributed environment to support efficient synchronous collaborative work between virtual teams, and experiment such an environment in the construction and telecommunication working sectors","Title: A collaborative platform for fixed and mobile networks\nYear: 2002\n\nAbstract: C/Webtop: providing users with a means for collaborating while on the move.","Title: Adding extensible synchronization capabilities to the agent model of a FIPA-compliant agent platform\nYear: 2000\n\nAbstract: In this paper, we present an agent platform, called JADE (Java Agent Development Environment), that tries to ease development applications in compliance with the FIPA specifications. Moreover, we describe an extension to JADE original agent model that allows expressing agent synchronisation constraints better and provides wider foundations to build higher-level agent architecture on. JADE agent model is more \"primitive\" than the agent models offered by other systems, and mainly deals with message handling and plan scheduling. Exploiting research results about concurrent OO languages, JADE agent model has been extended in a way that solves the inheritance anomaly problem and will be useful to JADE users when they will create more complex agents.","Title: Open Social Networking for Online Collaboration\nYear: 2013\n\nAbstract: Features of online social networks are being introduced in various applications and environments, including tools supporting virtual teams and online collaboration in general. In fact, social networking has a large potential for easing collaboration, also across organizational boundaries. However, effective e-collaboration through social networks requires the development of open and interoperable systems, allowing people belonging to different organizations to create ties, reflecting real connections existing in daily activities. Attention has to be paid to identity management, for allowing users to develop their reputation consistently, and to privacy and confidentiality, for creating a more trustful environment and protecting freedom of expression. In this article, the authors propose a novel peer-to-peer system, named Blogracy, leveraging the large BitTorrent network. Its main distinguishing features are: i protection of users' identity and privacy, ii absence of central control over published content; iii interoperability with other systems; and iv low costs and scalability of the infrastructure.","Title: Enabling Vocal Interaction in a Web Portal Environment.\nYear: 2006\n\nAbstract: The growing request of innovative, multimodal interfaces for mobile users and the need of different navigation paradigms for impaired Internet users are promoting and driving nowadays research on multimodal interactions. In this paper we present our experiences in the integration of vocal components in a portal engine, namely Apache Jetspeed. First, we discuss the reasons why the integration of a full-featured portal brings significant advantages to the development of a vocal platform. Then, we describe two complementary approaches for enhancing portals with vocal capabilities, and we compare them under various standpoints. The first approach that we investigate is based on a server-side speech synthesizer, while the second relies on client-side technologies, X+V and the SALT markup languages. For each of these approaches we present some examples and we discuss advantages and drawbacks.","Title: An ontology support for semantic aware agents\nYear: 2005\n\nAbstract: The work presented in this paper is an attempt to bridge two co-existing realties: Semantic Web and Multi-Agent Systems. Semantic aware agents will be able to interoperate in a semantic way as well as to produce and consume semantically annotated information and services. Agents should be enhanced with tools and mechanisms in order to autonomously achieve these strategic and ambitious objectives. In this paper, we focus on what we consider the central issue when moving towards the vision of semantic multi-agent systems: the ontology management support. Due to the heterogeneity of resources available and roles played by different agents of a system, a one-level approach with the aim of being omni comprehensive seems to be seldom feasible. In our opinion, a good compromise is represented by a two-level approach: a light ontology management support embedded in each agent and one or more ontology servers, providing a more expressive and powerful support.","Title: Low Cost Databases for NOW\nYear: 1999\n\nAbstract: . In this paper, we present a system called DONOW (Databaseon Network of Workstation), that is an example of an implementationand maintenance of a low cost distributed database without performancespenalties. The system has a three tier architecture based on aclient, a service and a data layer. The client layer allows local and remoteusers to interact with the system through a Java user friendly interface.The service layer is implemented in C++; it allows the service of userrequests and,...","Title: Agent-based interpretations of classic network models\nYear: 2013\n\nAbstract: The paper is aimed at developing agent-based variants of traditional network models that make full use of concurrency. First, we review some classic models of the static structure of complex networks with the objective of developing agent-based models suited for simulating a large-scale, technology-enabled social network. Secondly, we outline the basic properties that characterize such networks. Then, we briefly discuss some classic network models and the properties of the networks they generate. Finally, we discuss how such models can be converted into agent-based models (i) to be executed more easily in heavily concurrent environments and (ii) to serve as basic blocks for more complex agent-based models. We evidence that many implicit assumptions made by traditional models regarding their execution environment are too expensive or outright impossible to maintain in concurrent environments. Consequently, we present the concurrency issues resulting from the violation of such assumptions. Then, we experimentally show that, under reasonable hypothesis, the agent-based variants maintain the main features of the classic models, notwithstanding the change of environment. Eventually, we present a meta-model that we singled out from the individual classic models and that we used to simplify the agent-oriented conversion of the traditional models. Finally, we discuss the software tools that we built to run the agent-based simulations.","Title: JADE: a FIPA2000 compliant agent development environment\nYear: 2001\n\nAbstract: JADE (Java Agent Development Framework) is a software environment to build agent systems for the management of networked information resources in compliance with the FIPA2000 specifications for interoperable intelligent multi- agent systems. The goal of JADE is to simplify development while ensuring standard compliance through a comprehensive set of system services and agents. JADE offers an agent runtime system on which implement efficient FIPA 2000 compliant multi- agent systems and supports their development through the availability of a predefined programmable agent model and of a set of management and testing tools. This paper describes the main features of the JADE system and introduces some of the most important projects based on JADE software.","Title: Developing Multi-agent Systems with JADE\nYear: 2000\n\nAbstract: JADE (Java Agent Development Framework) is a software framework to make easy the development of multi-agent applications in compliance with the FIPA specifications. JADE can then be considered a middle-ware that implements an efficient agent platform and supports the development of multi agent systems. JADE agent platform tries to keep high the performance of a distributed agent system implemented with the Java language. In particular, its communication architecture tries to offer flexible and efficient messaging, transparently choosing the best transport available and leveraging state-of-the-art distributed object technology embedded within Java runtime environment. JADE uses an agent model and Java implementation that allow good runtime efficiency, software reuse, agent mobility and the realization of different agent architectures.","Title: Using PVM to develop a distributed object-oriented language for heterogeneous processing\nYear: 1998\n\nAbstract: This paper presents an object-oriented distributed language, called PVOOL, that is a good tool for developing real distributed applications. PVOOL is based on active objects called pv_units and concurrent message passing among them. The main feature of PVOOL is the possibility to coordinate the activity of different pv_units through virtual circuits. Virtual circuits are objects that indicate what are the operations to be performed, what are the pv_units that must do them, and what is the order in which they must be done to give a certain task. Virtual circuits can be dynamically created by pv_units and so this distributed object-oriented system can change its behavior during its life. PVOOL takes advantage of PVM procedures to perform objects distribution and message exchange, without explicitly writing low-level code. The use of PVM allows an easily distribution of a program, that is of its objects, on a heterogeneous network of parallel and serial computers. In particular, the paper describes how the features offered by PVOOL were useful to implement a flexible environment for the development of computer vision applications.","Title: A Multi Language Environment to Develop Multi Agent Applications\nYear: 1996\n\nAbstract: HOMAGE is an environment for the development of multi agent systems integrating agent and object-oriented programming paradigms and offering two different programming levels: object and agent. The object level allows the use of three object-oriented programming languages (C++, Common Lisp and Java) to develop new agent models as well as the components that will be used to build the body of agents. The agent level allows the development of new agents by defining their brain and by composing the components defined at the object level, and allows the development of multi agent systems by distributing and interconnecting agent instances. Moreover, these multi agent systems can be distributed on a net of heterogeneous machines connected through internet taking advantage of a set of communication and distribution libraries allowing the communication between agents through different protocols. The paper includes a brief description of a robotic application that we implemented during the experimentation of the environment.","Title: A security infrastructure for trust management in multi-agent systems\nYear: 2004\n\nAbstract: Multi-agent systems are based on the interaction of autonomous software components, the agents, which cooperate to achieve common goals. But such interactions, just as in human societies, can be set correctly only on the base of trust relations. This paper presents a security model founded on delegation certificates, which allows the management of security policies on the base of trust relations among autonomous software agents, collaborating and competing in wide, open and evolving agent societies. On the converse, the presence of a strong and flexible security infrastructure is fundamental to develop trust in counterparts and start advantageous interactions with them. While some of these concepts are already being adopted into the development of the security layer for JADE, a standard-based and widely deployed framework to build multi-agent systems, this paper includes further ideas which distributed multi-agent security frameworks could benefit from.","Title: A Distributed Object-Oriented Language for Heterogeneous Computer Networks\nYear: 1999\n\nAbstract: This paper presents an object-oriented distributed language, called CUBL++, that is a powerful tool for developing distributed applications on heterogeneous computer networks. CUBL++ is based on objects, called c_units, that communicate through synchronous and asynchronous message passing. A c_unit is an active object composed of data (state) and procedures as traditional (passive) objects, together with the capability of queueing incoming messages, when needed. C_units allow a programmer to implement an application on a heterogeneous architecture, as they communicate with each other without taking into account the physical characteristics of the actual node where they are located. We have experimented CUBL++ on a network where UNIX workstations, WindowsNT personal computers and transputers cooperate in order to perform a given task. In particular, this paper gives a brief description of a distributed system for image processing that has been implemented by using CUBL++.","Title: Multi-User and Security Support for Multi-Agent Systems\nYear: 2001\n\nAbstract: This paper discusses the requirements an agent system needs to be secure. In particular, the paper introduces a classification of modern distributed systems, and examines the delegation concept from a security point of view. After discussing the peculiar security and delegation issues present in distributed object systems, mobile agent systems and in multi agent systems, a case study is presented, describing the multi-user and security support that is being built into the JADE platform.","Title: ANEMONE - A Network of Multi-Agent Platforms for Academic Communities\nYear: 2005\n\nAbstract: This paper presents ANEMONE, a multi-agent platforms network that provides services for the academic community implemented by using the JADE agent development framework. In particular, ANEMONE provides a set of services to support i) academic people in some of their recurrent activities (fix an appointment, organize a meeting and search documents on the Web, ii) students in getting information about courses and iii) information technology people (including students) in getting information on documents and people that may help them to solve their programming problems. Moreover, it also provides a set of system-oriented services for the management of agent platforms and services and for the realization of new types of service.","Title: Mpool: An Object-Oriented Library For Task Composition And Co-Ordination\nYear: 1999\n\nAbstract: MPOOL is an object-oriented extension to the MPI library, based on three categories of objects, called units, groups and schemes. Units are active objects composed of data (state) and procedures (like traditional passive objects), but with the additional ability to store incoming messages in a queue while they are active and to send messages in parallel to other units; moreover, different units may be active simultaneously. Groups and schemes are passive objects used for the composition of units and the co-ordination of their actions, Groups manage collective communications and synchronization operations such as barriers. Schemes compose units' actions through the use of a set of constructs derived by path expressions.","Title: CoMMA: a multi-agent system for corporate memory management\nYear: 2002\n\nAbstract: In this paper, we present CoMMA (Corporate Memory Management through Agents), an open, agent-based system for the management of a corporate memory that was realized integrating several emerging technologies: agent technology, knowledge modeling, XML technology, information retrieval and machine learning techniques. In particular, the system has been realized to help users in the management of an organization corporate memory and in particular to facilitate the creation, dissemination, transmission and reuse of knowledge in an organization. CoMMA system is a FIPA compliant agent system and has been implemented by using the JADE agent development software framework. CoMMA is the result of an international project funded by European Commission.","Title: An object-oriented language for distributed artificial intelligence\nYear: 1993\n\nAbstract: In this work, we are presenting an object-oriented language to define distributed artificial intelligence (DAI) systems. This language allows for the description of control and communication management, a hierarchical representation of a DAI system at different levels of detail, and the simulation of its performance.","Title: Developing Real Applications With Agent Technologies.\nYear: 1999\n\nAbstract: In this paper, we present an agent library to develop multi-agent applications. Such an agent library has been realised taking into account FIPA specifications. FIPA specifications give the minimum amount of technology deemed necessary for the management of agents in an open agent system, including agent roles, an agent communication language, an agent management content language, and a standard way to interact with non-agentised software.","Title: What Agent Middleware Can (And Should) Do For You\nYear: 2002\n\nAbstract: This paper addresses the issue of moving agent technology to the mainstream, looking from various perspectives at the mainstreaming process that can take place during a technology life cycle, radically moving its status from a supposedly good idea to an actual economic and industrial workhorse that lends itself useful in everyday life. While there is serious evidence that agent technology is approaching this critical point, it is by no means possible to tell whether agent technology will eventually be adopted on a global scale or not. However, looking at the various factors that can make the difference between acceptance and oblivion, a mainstreaming strategy can be set up. We claim that agent middleware has to play a fundamental role in this strategy, and we motivate our belief on the basis of general considerations and on our actual experience with the JADE agent platform.","Title: MAP - a Language for the Modelling of Multi-Agent Systems\nYear: 1993\n\nAbstract: This paper presents a distributed object-oriented language, called Multi-Agent Programming language, whose features are suitable to develop multi-agent systems. This language is based on an object, called agent, (i) performing private actions, (ii) communicating with other agents, and (iii) re-configuring system structure through the creation of other agents and changing its behaviour. The main feature of this language is the use of a large set of communication primitives, defined on the spirit of Speech Act theory, which are suitable to model agent interactions and which can be specialised to implement specific communication protocols. In particular, the paper shows how these primitives are suitable to model negotiation protocols.","Title: Automatic Storing and Retrieval of Large Collections of Images\nYear: 1998\n\nAbstract: This paper, presents a system, SISTER, that is suitable for storing and retrieve of large collections of images allowing the user to formulate queries for different image categories on the basis of color information and specific attributes of the image category; this is possible, because SISTER can be easily adapted to support new image categories specializing the acquisition and the retrieval subsystems. SISTER is composed of three parts: i) an image acquisition subsystem automatically extracting the attributes from images, ii) a database management subsystem maintaining the descriptions of images, and iii) a retrieval subsystem allowing the user to retrieve images through a user-friendly graphical interface. The acquisition subsystem extracts image attributes combining image processing and inductive classification modules. Classification modules are useful because they may allow the extraction of attributes that cannot be extracted through image processing techniques and because they may allow the reduction of the error percentage made by the image processing modules in the acquisition of image attributes.","Title: Implementation Level Issues in MAS Modeling.\nYear: 2003\n\nAbstract: Abstract - The aim of this paper is to focus on the issues connected with the diagrammatic notations and tools, which should support developers when moving from the design phase towards the implementation phase of MASs The paper deals with three main research lines: the representation of the inter - actions between agents and their relationship with the internal architecture of the single agent, the deployment of MASs, and the pattern reuse","Title: An efficient and flexible C++ library for concurrent programming\nYear: 1998\n\nAbstract: A major problem for the integration of concurrency in object-oriented languages is the so-called inheritance anomaly, i.e. the conflicts between inheritance and concurrency that often cause the need to redefine inherited methods in order to maintain the integrity of objects. Several solutions have been proposed for resolving these conflicts. However, some of them are incomplete, and do not solve all types of inheritance anomaly; others make the definition of classes complex and/or their implementation inefficient. This paper describes a C++ library for concurrent programming that provides a comprehensive framework particularly suitable for coarse-grained distributed applications. This library copes with the inheritance anomaly problem, presenting a solution that minimizes the redefinition of inherited methods without increasing the complexity to write them. This solution is based on the use of a special set of methods, called interface methods, composed of a body and two sets of synchronization constraints. These two sets of synchronization constraints are respectively used to enable the execution of their method body and to disable the methods that cannot be executed after their method. (C) 1998 John Wiley & Sons, Ltd.","Title: A Multi-Agent Framework to Join DTV and Virtual Communities\nYear: 2006\n\nAbstract: In this paper present a multi-agent framework for integrating the emergent technology of the interactive digital television with new types of services to support the cooperative activities of different types of virtual communities. As an example of such kind of service we present a community game, in which we have a real-time interaction between two DTV users, and an online auction, in which although the interaction is asynchronous.","Title: JADE: A software framework for developing multi-agent applications. Lessons learned\nYear: 2008\n\nAbstract: Since a number of years agent technology is considered one of the most innovative technologies for the development of distributed software systems. While not yet a mainstream approach in software engineering at large, a lot of work on agent technology has been done, many research results and applications have been presented, and some software products exists which have moved from the research community to the industrial community. One of these is JADE, a software framework that facilitates development of interoperable intelligent multi-agent systems and that is distributed under an Open Source License. JADE is a very mature product, used by a heterogeneous community of users both in research activities and in industrial applications. This paper presents JADE and its technological components together with a discussion of the possible reasons for its success and lessons learned from the somewhat detached perspective possible nine years after its inception.","Title: A development toolkit to realize autonomous and interoperable agents\nYear: 2001\n\nAbstract: Autonomy and inter- operability are two characteristics of software agents that are advocating agent technology as an ideal candidate to support next generation of software systems. This paper presents a Java development toolkit supporting the realization of autonomous and inter- operable agents. This toolkit provides the developer with a goal- oriented agent architecture for FIPAcompliant agents. Goal- orientation supports autonomy because the developer is no longer requested to describe what the agent should do in reaction to events. To this extent, our development toolkit provides a planning engine capable of building plans to achieve the agents goals autonomously. Goal- orientation is also a key aspect of inter- operability because it is the basis of the semantics of FIPA ACL. Our development toolkit can be used at two levels of abstraction. The higher level, that we call the agent level, allows describing the agent in terms of its natural characteristics such as goals, beliefs and social organization. A code generator producing Java skeletons from UML diagrams supports this level. The developer can choose any UML CASE tool to model her agents because this code generator works with files in a standard format. The generated skeletons must be completed with application- specific code at the lower level of abstraction, that we call object level. At this level, agents are seen as Java programs and the developer is provided with a development library to integrate her code within the generated skeletons. This two- level approach allows describing agents in their natural terms at the agent level, while supporting the integration of application- specific and legacy code at the object level. Moreover, the generated code can be customized at the object level to integrate application- specific optimizations.","Title: Dynamic Grid Tasks Composition And Distribution Through Agents\nYear: 2006\n\nAbstract: This paper presents a multi-agent system called GAIN (Grid Agent Infrastructure), which can be used for the development of flexible agent-based Grid systems. The system supports users both in the development and execution of Grid applications. In particular, GAIN allows the definition of workflow applications by composing different tasks made available by the Grid nodes. Furthermore, it follows the different phases of the execution of the workflow providing transparent allocation and re-allocation of the tasks on the different nodes of the Grid. A first prototype of the system has been realized by using the JADE agent development software and it has been tested in lab trials involving a network of different JADE platforms. In these trials, tasks provided both by the agents of the system and by external legacy software systems have been composed. Copyright (c) 2005 John Wiley & Sons, Ltd.","Title: An agent-based approach to manage negotiation protocols in flexible CSCW systems\nYear: 2000\n\nAbstract: Autonomous agents are often used to manage the complex situations arising in computer-supported collaborative activities. Anyway, agents are confined to accomplish only marginal tasks and cannot yet be considered integrated with CSCW systems. This paper describes CollAge, an agent-based CSCW system designed to promote the productivity of distributed meetings by means of agents. The system architecture assigns a personal agent to every meeting attendant and includes a project-manager agent and a resource-manager agent to deal with the activities related to arranging and managing the meetings.","Title: Janet: A Framework For Flexible Web-Content Retrieval\nYear: 2000\n\nAbstract: Quality-of-service negotiation is considered a fundamental step in the provision of multimedia content especially when only a low-bandwidth channel is available. The widespread adoption of the Web by home users and the increasing complexity of Web pages suggest to extend the existing negotiation protocols to generic Web contents. This should increase the flexibility of current document retrieval systems and should also help to manage the needs of users connecting through low-bandwidth channels. This paper describes how a quality-of-service can be associated with a generic Web content and presents a development framework that supports negotiation as a means to enhance flexibility in the retrieval of Web contents.","Title: Information Attacks on Online Social Networks\nYear: 2014\n\nAbstract: Online social networks have changed the way people interact, allowing them to stay in touch with their acquaintances, reconnect with old friends, and establish new relationships with other people based on hobbies, interests, and friendship circles. Unfortunately, the regrettable concurrence of the users' carefree attitude in sharing information, the often sub-par security measures from the part of the system operators and, eventually, the high value of the published information make online social networks an interesting target for crackers and scammers alike. The information contained can be used to trigger attacks to even more sensible targets and the ultimate goal of sociability shared by the users allows sophisticated forms of social engineering inside the system. This work reviews some typical social attacks that are conducted on social networking systems, carrying real-world examples of such violations and analysing in particular the weakness of password mechanisms. It then presents some solutions that could improve the overall security of the systems.","Title: Supporting Social Networks with Agents\nYear: 2014\n\nAbstract: Multi-agent systems have been contributing to the development of both theory and practice of complex distributed systems. Social networks are probably the systems that exhibit the highest degree of similarity with multi-agent systems because members of a social network interact as agents do in a multi-agent system. Multi-agent system may be the best solution to enrich and facilitate the interaction and the collaboration among the members of a social network. After an introduction on the relationships between multi-agent systems and social networks, this paper describes Blogracy, a multi-agent system that supports the interaction among the members of a social network.","Title: Representing real world phenomena through HDPTN\nYear: 1991\n\nAbstract: The authors present a model, called HDPTN (hierarchical and distributed process transition network), for the representation of real world phenomena. This model is based on two types of entities: circumstances and episodes. A circumstance is an elementary entity which can take on a set of discrete values over time, while an episode is a compound entity whose parts are a circumstance and/or other episodes acting concurrently. In particular, the hierarchical and distributed structure of the episode seems to be suitable for the modeling of systems which need real-time performance and the integration of representations and reasoning at different levels of detail","Title: Ontology based automatic speech recognition and generation for human-agent interaction\nYear: 2004\n\nAbstract: In this paper, we present a system that supports an automatic speech recognition and generation between users and an agent based application on the basis of the ontologies used in the application domain. The system is realized taking advantage of the JADE agent development framework and of the IBM Via Voice Tool and has been experimented in different applications fields testing agent - user interaction both in Italian and English. In particular, the paper introduces a short description of the use of the system for banking applications.","Title: Supporting cooperation with off-the-shelf applications in wired and wireless networks\nYear: 2001\n\nAbstract: This paper presents a cooperative platform that allows the sharing of information as well as the interactive use of different kinds of application in a synchronous mode. The access to the collaborative sessions is possible from different kinds of terminal and network (fixed or mobile). In particular, we address Web users and mobile users with sufficient bandwidth. The platform is based on the centralised sharing of an off-the-shelf application that relies on a collaborative version of the graphics libraries used in Java and Microsoft Windows. A first prototype of the platform has been experimented by Ph.D. students during a seminar distributed across Italy","Title: Agent-based Social Networks for Enterprise Collaboration\nYear: 2011\n\nAbstract: This paper discusses the relationship between agent technology and the recent wave of online social networks in the scope of the notable scenario of enterprise collaboration. In the brief introduction on the topic, we provide a coherent view of online social networks and social network systems. Then, we emphasize some features that can be considered as notable flaws that make everyday social networks and systems unusable to facilitate enterprise collaboration. Finally, we show how agent technology can address some of the mentioned flaws. The paper terminates with some concluding remarks and with an outline of future research directions.","Title: An Outline Of The Use Of Transition Systems To Formalize Jade Agents And Multi-Agent Systems\nYear: 2015\n\nAbstract: This paper presents the key aspects of a proposed formalization of JADE agents and multi-agent systems based on transition systems. Such a formalization is meant to be useful to describe and clarify how JADE multi-agent systems work and to provide a theoretical instrument to validate and analyze the semantics of JADE agents. This is needed to decouple agent-oriented and object-oriented parts of an agent design and to avoid misunderstandings on the semantics of JADE agents. The chosen approach is to define a structural operational semantics for Java programs written using JADE, and the proposed formalization consists in two parts: the first identifies and defines the main entities that together compose a JADE multi-agent system; the second provides the transition system and rewriting rules. The paper terminates with two explanatory examples of the usage of the transition system. A brief recapitulation of the work concludes the paper.","Title: Information and Password Attacks on Social Networks: An Argument for Cryptography\nYear: 2015\n\nAbstract: Online social networks have changed the way people interact, allowing them to stay in touch with their acquaintances, reconnect with old friends, and establish new relationships with other people based on hobbies, interests, and friendship circles. Unfortunately, the regrettable concurrence of the users' carefree attitude in sharing information, the often sub-par security measures from the part of the system operators and, eventually, the high value of the published information make online social networks an interesting target for crackers and scammers alike. The information contained can be used to trigger attacks to even more sensible targets and the ultimate goal of sociability shared by the users allows sophisticated forms of social engineering inside the system. This work reviews some typical social attacks that are conducted on social networking systems, carrying real-world examples of such violations and analysing in particular the weakness of password mechanisms. It then presents some solutions that could improve the overall security of the systems.","Title: Social Media for Online Collaboration in Firms and Organizations\nYear: 2016\n\nAbstract: AbstractParticipation in social networks has long been studied as a social phenomenon according to different theories. In particular, the notion of social capital highlights a person's benefit due to his relations with other persons, including family, colleagues, friends and generic contacts. It may be important both for the individuals that are able to accumulate large amounts, and for organizations. Nowadays, social networking systems bring many acquaintances online, both in the private and working spheres. Some systems are used both at home, for leisure goals, and on the work place, professionally. In the vast majority of cases, social networking platforms are still used without corporate blessing. However, several traditional information systems, such as CRMs and ERPs, have also been modified in order to include social aspects. This article shows the role of social capital in the participation in online social networking activities, in the various cases of Virtual Organizations, Virtual Teams, and online Networks of Practice. It describes the present situation, which is characterized by great promises and mixed initial results, and some possible prospects.","Title: Blogracy: A Peer-to-Peer Social Network\nYear: 2016\n\nAbstract: AbstractThe current approach to build social networking systems is to create huge centralized systems owned by a single company. However, such strategy has many drawbacks, e.g., lack of privacy, lack of anonymity, risks of censorship and operating costs. In this paper the authors propose a novel P2P system that leverages existing, widespread and stable technologies such as DHTs and BitTorrent. In particular, they introduce a key-based identity system and a model of social relations for distributing content efficiently among interested readers. The system they propose, Blogracy, is a micro-blogging social networking system focused on: i anonymity and resilience to censorship; ii authenticatable content; iii semantic interoperability using activity streams. The authors have implemented the system and conducted various experiments to study its behaviour. The results are presented here, regarding i communication delays for some simulations of node churn, ii delays measured in test operations over PlanetLab, in direct communication, and iii through the I2P anonymizing network.","Title: Core Features of an Agent-Oriented Domain-Specific Language for JADE Agents.\nYear: 2016\n\nAbstract: This paper presents the core features of JADEL, an agent-oriented domain-specific programming language for the construction of JADE agents, behaviours and ontologies. The work on JADEL originates from the need to assist programmers by means of tools that reduce the complexity and speed up the construction of a JADE agents and multi-agent systems. The features of JADEL discussed in this paper include abstractions for the main entities of JADE-agents, behaviours and ontologies-and they also encompass the features needed for the construction of domain-specific tasks, thus enriching JADE APIs with novel and simple notations.","Title: Interaction protocols in the JADEL programming language.\nYear: 2016\n\nAbstract: This paper presents the support for interaction protocols that has been recently added to the JADEL programming language. JADEL is an agent-oriented programming language designed to ease the development of JADE agents and multi-agent systems by offering general-purpose agent-oriented abstractions to the programmer. The first part of the paper presents JADEL and motivates the need for a new agent-oriented programming language. Then, the agent-oriented abstractions that JADEL has been providing since its first version-namely agents, behaviours and communication ontologies-are described. The new support for interaction protocols is finally presented, and a simple example of a JADEL multi-agent system that uses interaction protocols is reported. The paper is concluded with an overview of the current state of JADEL and related tools.","Title: A Comparison between Asynchronous Backtracking Pseudocode and its JADEL Implementation.\nYear: 2017\n\nAbstract: In this paper, a comparison between the pseudocode of a well-known algorithm for solving distributed constraint satisfaction problems and the implementation of such an algorithm in JADEL is given. First, background and motivations behind JADEL development are illustrated. Then, we make a description of the problem and a brief introduction to JADEL. The core of this work consists in the translation of the algorithm pseudocode in JADEL code, which is described in details. Scope of the paper is to evaluate such a translation, in terms of closeness to pseudocode, complexity, amount of code written and performance.","Title: Preserving Privacy in a P2P Social Network.\nYear: 2016\n\nAbstract: Building centralized social networking systems has many drawbacks, e.g., lack of privacy, lack of anonymity, risks of censorship, and operating costs. As it is discussed in this article, an alternative approach is possible. A prototype system, named Blogracy, has been realized as a micro-blogging social networking system, based on well-known P2P technologies, such as DHTs and BitTorrent. In particular, this article presents the security architecture of the system, which relies on a key-based identity system and a scheme for attribute-based content encryption, with multiple authorities. Moreover, some empirical results obtained in test operations over PlanetLab are presented, comparing plain and I2P anonymized communications.","Title: Agent-oriented model-driven development for JADE with the JADEL programming language.\nYear: 2017\n\nAbstract: This paper describes, from motivations and main objectives to actual implementation, a novel agent-oriented programming language called JADEL. JADEL is designed to support the effective implementation of JADE agents and multi-agent systems in the scope of real-world model-driven development because it concretely helps developers by natively supporting agent-oriented abstractions, and because it is based on mature industrial-strength technologies. The four core abstractions that JADEL supports, namely agents, behaviours, communication ontologies, and interaction protocols, are presented by gradually introducing the specific syntaxes that the language provides for them. In the last part of the paper, a complete example of a simple JADEL multi-agent system is presented and discussed. Such an example is a well-known example from the official distribution of JADE and many programmers learned the basics of JADE from it. The choice of this example allows comparing JADEL source code with reference Java source code using JADE, and it clearly emphasizes the practical advantages of agent-oriented programming.","Title: Automatic Creation of a Large and Polished Training Set for Sentiment Analysis on Twitter.\nYear: 2017\n\nAbstract: Within the field of sentiment analysis and emotion detection applied to tweets, one of the main problems related to the construction of an automatic classifier is the lack of suitable training sets. Considering the tediousness of manually annotating a training set, and the noise present in data collected directly from the social web, in this paper we propose an iterative learning approach, which combines distant supervision with dataset pruning techinque. In particular, following the \"eat your own dogfood\" idea, we have applied a classifier, trained on raw data obtained from different Twitter channels, to the same original dataset, for removing the most doubious instances automatically. This kind of approach has been used to obtain a more polished training set for emotion classification, based on Parrot's model of six basic emotions. On the basis of the achieved results, we argue that the automatic filtering of training sets can make the application of the distant supervision approach more effective in many use cases.","Title: Actors Based Agent Modelling and Simulation.\nYear: 2018\n\nAbstract: Agent-based modeling and simulation are some powerful techniques that are widely used with success for analyzing complex and emergent phenomena in many research and application areas. Many different reasons are behind the success of such techniques, among which an important mention goes to the availability of a great variety of software tools, that ease the development of models, as well as the execution of simulations and the analysis of results. However, the agent models provided by such tools do not offer the features of the computational agents found in multi-agent systems or distributed artificial intelligence techniques. Therefore, it is difficult to use such tools to model complex systems defined by autonomous, proactive and social entities. This paper presents an actor software library, called ActoDeS, for the development of concurrent and distributed systems, and shows how it can be a suitable mean for building flexible and scalable ABMS applications.","Title: A holistic system for troll detection on Twitter.\nYear: 2018\n\nAbstract: Various techniques based on artificial intelligence have been proposed for the automatic detection of online anti-social behaviors, both in existing systems and in the scientific literature. In this article, we describe TrollPacifier, a holistic system for troll detection, which analyses many different features of trolls and legitimate users on the popular Twitter platform. In this system, the most known and promising approaches and research lines are applied, along with original new ideas, in a form that fits such a large public platform. In particular, we have identified six groups of features, based respectively on the analysis of writing style, sentiment, behaviors, social interactions, linked media, and publication time. As its main scientific contributions, this work provides: (i) an up-to-date analysis of the state of the art for the problem of troll detection; (ii) the systematic collection and grouping of features, on Twitter; (iii) the description of a working holistic system for troll detection, with a very high accuracy (95.5%); and (iv) a comparison among the different features, with a machine learning approach. Our results demonstrate that automatic classification can be useful in the whole process of identification and management of online anti-social behaviors. However, a multi-faceted approach is required, in order to obtain an adequate accuracy.","Title: A Week of Playing with Code, the Object-Oriented Way.\nYear: 2018\n\nAbstract: This work presents the results of some summer stages for high school students, for the first introduction to computational thinking and programming. Differently from other approaches, our experiences are characterized by: (i) a full week of lessons and exercises, for gradually developing a small but complete and original project, (ii) an objects-early methodology, (iii) the choice of a dynamic videogame as the main programming project, and (iv) the availability of few small and focused examples, as source files, for students to start building their own application. At the end, the students' anonymous opinions about the stage, and their own projects, were collected and analyzed, for improving future similar activities.","Title: A Multi-Agent Architecture for Data Analysis.\nYear: 2019\n\nAbstract: ActoDatA (Actor Data Analysis) is an actor-based software library for the development of distributed data mining applications. It provides a multi-agent architecture with a set of predefined and configurable agents performing the typical tasks of data mining applications. In particular, its architecture can manage different users' applications; it maintains a high level of execution quality by distributing the agents of the applications on a dynamic set of computational nodes. Moreover, it provides reports about the analysis results and the collected data, which can be accessed through either a web browser or a dedicated mobile APP. After an introduction about the actor model and the software framework used for implementing the software library, this article underlines the main features of ActoDatA and presents its experimentation in some well-known data analysis domains.","Title: Island model in ActoDatA: an actor-based implementation of a classical distributed evolutionary computation paradigm\nYear: 2021\n\nAbstract: ABSTRACTIn this paper, we make a first assessment of the performance of ActoDatA, a novel actor-based software library for distributed data analysis and machine learning in Java that we have recently developed. To do so we have implemented an evolutionary machine learning application based on a distributed island model. The model implementation is compared to an equivalent implementation in ECJ, a popular general-purpose evolutionary computation library that provides support for distributed computing. The testbed used for comparing the two distributed versions has been an application of Sub-machine code Genetic Programming to the design of efficient low-resolution binary image classifiers. The results we have obtained show that the ActoDatA implementation is more efficient than the corresponding ECJ implementation.","Title: Continual representation learning for node classification in power-law graphs\nYear: 2022\n\nAbstract: The recent advent of node embedding techniques enabled a more efficient application of machine learning techniques on graphs. These techniques allow each node of a network to be encoded into an arbitrary low-dimensional vector representation, which can be exploited by statistical learning models. However, the main limitation of these approaches is that the embedding task is solved as an optimization problem on a static snapshot of the graph. In a real scenario, temporal dynamics should be considered with some consequences: new nodes might join the network and get a representation of only these new ones. As a consequence, a new training step over the entire graph is required. Even more, training models with static approaches can have resource-intensive requirements, especially when dealing with large networks. In light of this, a continual feature learning that builds on top of previously already learned knowledge (previous partial embedding of the network) and well-known properties can be a solution to address both limitations efficiently in real scenarios. Our approach is suitable for graphs whose degree distribution is described by a power-law function that is a common property of real systems. This research work presents three main scientific contributions: (a) a continual feature learning meta-algorithm for node embedding, which exploits properties of power-law distribution and spaces alignment techniques; It is suitable with any traditional node embedding techniques that relies on embedding spaces (b) we demonstrate empirically, by performing node labeling tasks, that a lightweight solution to encode new nodes, based on limited knowledge of the embedding of the network hub-nodes, can provide comparable or better performances, with respect to static approaches. (c) Finally, we experimented our algorithm in the temporal graphs domain and we achieved better results in node classification compared with other state of the art techniques.","Title: Mobility in Unsupervised Word Embeddings for Knowledge Extraction-The Scholars' Trajectories across Research Topics\nYear: 2022\n\nAbstract: In the knowledge discovery field of the Big Data domain the analysis of geographic positioning and mobility information plays a key role. At the same time, in the Natural Language Processing (NLP) domain pre-trained models such as BERT and word embedding algorithms such as Word2Vec enabled a rich encoding of words that allows mapping textual data into points of an arbitrary multi-dimensional space, in which the notion of proximity reflects an association among terms or topics. The main contribution of this paper is to show how analytical tools, traditionally adopted to deal with geographic data to measure the mobility of an agent in a time interval, can also be effectively applied to extract knowledge in a semantic realm, such as a semantic space of words and topics, looking for latent trajectories that can benefit the properties of neural network latent representations. As a case study, the Scopus database was queried about works of highly cited researchers in recent years. On this basis, we performed a dynamic analysis, for measuring the Radius of Gyration as an index of the mobility of researchers across scientific topics. The semantic space is built from the automatic analysis of the paper abstracts of each author. In particular, we evaluated two different methodologies to build the semantic space and we found that Word2Vec embeddings perform better than the BERT ones for this task. Finally, The scholars' trajectories show some latent properties of this model, which also represent new scientific contributions of this work. These properties include (i) the correlation between the scientific mobility and the achievement of scientific results, measured through the H-index; (ii) differences in the behavior of researchers working in different countries and subjects; and (iii) some interesting similarities between mobility patterns in this semantic realm and those typically observed in the case of human mobility.","Title: Fine-Grained Agent-Based Modeling to Predict Covid-19 Spreading and Effect of Policies in Large-Scale Scenarios\nYear: 2022\n\nAbstract: Modeling and forecasting the spread of COVID-19 remains an open problem for several reasons. One of these concerns the difficulty to model a complex system at a high resolution (fine-grained) level at which the spread can be simulated by taking into account individual features. Agent-based modeling usually needs to find an optimal trade-off between the resolution of the simulation and the populati...","Title: High-Performance Computing and ABMS for High-Resolution COVID-19 Spreading Simulation\nYear: 2022\n\nAbstract: This paper presents an approach for the modeling and the simulation of the spreading of COVID-19 based on agent-based modeling and simulation (ABMS). Our goal is not only to support large-scale simulations but also to increase the simulation resolution. Moreover, we do not assume an underlying network of contacts, and the person-to-person contacts responsible for the spreading are modeled as a function of the geographical distance among the individuals. In particular, we defined a commuting mechanism combining radiation-based and gravity-based models and we exploited the commuting properties at different resolution levels (municipalities and provinces). Finally, we exploited the high-performance computing (HPC) facilities to simulate millions of concurrent agents, each mapping the individual's behavior. To do such simulations, we developed a spreading simulator and validated it through the simulation of the spreading in two of the most populated Italian regions: Lombardy and Emilia-Romagna. Our main achievement consists of the effective modeling of 10 million of concurrent agents, each one mapping an individual behavior with a high-resolution in terms of social contacts, mobility and contribution to the virus spreading. Moreover, we analyzed the forecasting ability of our framework to predict the number of infections being initialized with only a few days of real data. We validated our model with the statistical data coming from the serological analysis conducted in Lombardy, and our model makes a smaller error than other state of the art models with a final root mean squared error equal to 56,009 simulating the entire first pandemic wave in spring 2020. On the other hand, for the Emilia-Romagna region, we simulated the second pandemic wave during autumn 2020, and we reached a final RMSE equal to 10,730.11.","Title: Machine Learning for Bankruptcy Prediction in the American Stock Market: Dataset and Benchmarks\nYear: 2022\n\nAbstract: Predicting corporate bankruptcy is one of the fundamental tasks in credit risk assessment. In particular, since the 2007/2008 financial crisis, it has become a priority for most financial institutions, practitioners, and academics. The recent advancements in machine learning (ML) enabled the development of several models for bankruptcy prediction. The most challenging aspect of this task is dealing with the class imbalance due to the rarity of bankruptcy events in the real economy. Furthermore, a fair comparison in the literature is difficult to make because bankruptcy datasets are not publicly available and because studies often restrict their datasets to specific economic sectors and markets and/or time periods. In this work, we investigated the design and the application of different ML models to two different tasks related to default events: (a) estimating survival probabilities over time; (b) default prediction using time-series accounting data with different lengths. The entire dataset used for the experiments has been made available to the scientific community for further research and benchmarking purposes. The dataset pertains to 8262 different public companies listed on the American stock market between 1999 and 2018. Finally, in light of the results obtained, we critically discuss the most interesting metrics as proposed benchmarks for future studies."],"string":"[\n \"Title: Modeling Deployment and Mobility Issues in Multiagent Systems Using AUML\\nYear: 2003\\n\\nAbstract: This paper demonstrates how UML can be exploited and extended to model the deployment of a multiagent system at the agent level. This is accomplished by extending the formally-based UML 2.0 metamodel to support the semantics of agents, mobile agents and their supporting platforms. Additionally, the UML-based notation, used to model the deployment of a multiagent system, takes advantage of stereotypes to associate an agent-oriented semantics with the model elements used in the diagram. A primary objective of this paper is to demonstrate that the Agent UML (AUML) deployment diagram can be successfully applied to real-world applications. This AUML work is organized as an activity within the FIPA Modeling Technical Committee.\",\n \"Title: A Two-Level Approach for Ontology Management in Multi-Agent Systems\\nYear: 2005\\n\\nAbstract: This paper addresses the need for strong security guarantees in increasingly dynamic and flexible information technology (IT) environments. It applies time-tested security principles, architectural patterns, and continuous improvement constructs to weave ...\",\n \"Title: Extending JADE for Agent Grid Applications\\nYear: 2004\\n\\nAbstract: This paper presents an extension of the JADE agent development framework that may be the basis for the realization of flexible agent-based grid systems. In particular, JADE framework has been enriched with two new types of agents that, on the one hand simplify the distribution of tasks inside a grid of agent platforms, and, on the other hand, facilitate the composition of tasks through the use of production rules. Moreover, the paper describes how such kinds of operations are executed through the proper authentication and authorization mechanisms.\",\n \"Title: Supporting Social Networks With Agent-Based Services\\nYear: 2013\\n\\nAbstract: Current approaches to build social networking systems are based on a centralized architecture because it allows a simple browser-based user experience and makes easier and more efficient to implement many algorithms used in a social networking site e.g., friend suggestion, However this kind of architecture has many drawbacks for its users, e.g., lack of privacy, lack of anonymity, risks of censorship and operating costs. This paper presents a system, called Blogracy, which uses widespread and stable peer-to-peer technologies, such as distributed hash tables and BitTorrent, for coping with intrinsic defects of centralized architectures and for being the basis of solid distributed social networking platforms. Moreover, Blogracy takes advantages of multi-agent systems for simplifying the implementation of social network services in a decentralized setting.\",\n \"Title: A Development Environment for the Realization of Open and Scalable Multi-agent Systems\\nYear: 1999\\n\\nAbstract: This paper presents a development environment suitable for the design and implementation of multi-agent systems. This environment is designed following the guidelines found in HPA specifications. Therefore, it offers the management agents and services necessary to realize a RPA-compliant open system. An agent prototype is also provided in order to ease the implementation of domain-specific agents. Even if the development environment mainly supports the C++ language, the resulting architectures are heavily based on the concept of roaming agent through a distributed environment. Interoperability with other systems, supporting other languages such as Java, is guaranteed by FIPA specifications. The presented environment has been used to develop a multi-agent system that should integrate the different software modules performing sensory data interpretation, planning and faults diagnosis of a robot working in a space station.\",\n \"Title: An agent model platform for realizing efficient and reusable agent software\\nYear: 2000\\n\\nAbstract: In this paper, we present an agent model and platform we defined and implemented to realize efficient and reusable agent software through an agent development environment called JADE. JADE (Java Agent Development Environment) is a software framework to make easy the development of agent applications in compliance with the FIPA specifications for interoperable intelligent multi-agent systems. 1. JADE AGENT PLATFORM The JADE Agent Platform complies with the FIPA specifications [2] and includes all those mandatory agents that manage the platform, that is the ACC, the AMS, and the DF. Agent communication is performed through message passing, where FIPA ACL is the language to represent messages. JADE communication architecture tries to offer flexible and efficient messaging, transparently choosing the best transport a'¢ailable and leveraging state-of-the-art distributed object technology embedded within Java runtime environment. While appearing as a single entity to the outside world, a JADE agent platform is itself a distributed system, since it can be split over several hosts with one among them acting as a front end for interplatform IIOP communication. A JADE system is made by one or more Agent Container, each one living in a separate Java Virtual Machine and deiivering runtime environment support to JADE agents. Java RMI is used to communicate among the containers and each one of them can also act as an IIOP client to forward outgoing messages to foreign agent platforms. A special, Front End container is also an IIOP server, listening at the official agent platform ACC address for incoming messages from other platforms. The two mandatory system agents, that is the AMS and the default DF, run within the front-end container.\",\n \"Title: Ontology-Based Remote Collaboration for the Development of Software System\\nYear: 2005\\n\\nAbstract: RAP (Remote Assistant for Programmers) is a Web and multi-agent based system to support remote students and programmers during common pro- jects or activities based on the Java programming language. RAP helps users to solve problems proposing information extracted from dedicated repositories and forwarding answers received from other users, recommended as experts. Its peculiar characteristic is the integration of the agent technology with the seman- tic Web technology. In fact, in order to improve filtering and recommendation techniques, RAP takes advantage of an ontological approach to user and docu- ment profiling. A RAP system is not a closed system, instead it is based on a dynamic network of RAP platforms managing groups of geographically local- ized users and documents. Therefore, recommendations should take into ac- count of the accessible experts and documents. At this purpose, RAP users and documents profile management subsystems provide a mechanism that dynami- cally adapts the relevance of each profile. An initial prototype of the RAP Sys- tem is under development by using JADE.\",\n \"Title: Attribute grammars as a robust technical basis for a human-computer interaction general purpose architecture\\nYear: 1997\\n\\nAbstract: In this paper, we present a Natural Language Interface (NLI) that combines some of the advantages of using general purpose grammars with some of the features found in semantic grammars. This is achieved by an Attribute Grammar so as to create an intermediate representation which is interpreted in terms of domain-specific routines. NLI has been used as a component of a Human–Computer Interaction (HCI) system, working on different domains. After a discussion of the theory underlying the system, two examples of the use of NLI on practical domains are described: the first is in the field of three-dimensional scene generation, the second in the field of road map car planning. Some evaluation issues are also included in this paper.\",\n \"Title: Enabling FIPA Agents on Small Devices\\nYear: 2001\\n\\nAbstract: The foreseen progress of the market of portable devices is demanding the realisation of increasingly complex applications for increasingly smaller and ubiquitous devices. This trend promotes the migration of technologies that were originally developed for desktop computers to mobile devices. This paper describes the current results of the LEAP project, a European-scale effort that aims at enabling FIPA agents on small devices. The LEAP project achieves its goal providing a FIPA-compliant agent platform that runs seamlessly on any Java-enabled device, from cellular phones to enterprise servers. This platform is naturally ubiquitous as it can be configured to run on any mobile or fixed device. The LEAP project has already released a first version of the platform to registered users for testing purposes and the second, and final, version will be released in open source by the end of this year. We tested the platform in a logistics scenario intended to provide mobile workers with \\\"just-in-time information.\\\"\",\n \"Title: A Collaborative and Multi-Agent Approach to E-mail Filtering\\nYear: 2005\\n\\nAbstract: CAFE (Collaborative Agents for Filtering E-mails) is a multi-agent system to collaboratively filter spam from usersý mail. CAFE associates each user with a proxy agent that acts as an interface between the userýs e-mail client and the server. With the support of other agents, the proxy agent classifies messages into three categories: ham (good messages), spam and spam-presumed. The system analyzes each message using three approaches: the first is based on an hash function, the second (static) on DNSBL (DNS-based Black Lists) databases and the third (dynamic) on a Bayesian filter. We give a mathematical representation of the system, showing that if the users collaborate, the fault probability decreases in proportion to the number of active users.\",\n \"Title: DAISY: an object-oriented system for Distributed Artificial Intelligence\\nYear: 1994\\n\\nAbstract: This paper presents an object-oriented distributed system, called DAISY, for the development and experimentation of Distributed Artificial Intelligence systems and algorithms. This system is based on two programming levels: object level and agent level. Both the levels allow to define, implement and experiment systems. While the object level offers a large set of low level programming means (a large set of program constructs, a set of low level communication procedures, and so on), the agent level, which is implemented on the object level, offers a limited set of high level programming means (few program constructs, a fixed set of high level communication procedures derived by speech act theory and a fixed set of high level procedures to manage agent's knowledge). In particular, the paper shows the use of DAISY for modeling an airline reservation scenario and a manufacturing plant scenario.\",\n \"Title: Deploying FIPA-Compliant Systems on Handheld Devices\\nYear: 2001\\n\\nAbstract: LEAP is a runtime environment for deploying agents on a network of Java-enabled devices. It complies with FIPA international standards for multiagent systems.\",\n \"Title: Supporting Agent-Oriented Modelling With Uml\\nYear: 2002\\n\\nAbstract: Software engineering relies on the possibility of describing a system at different levels of abstraction. Agent-oriented software engineering introduces a new level of abstraction, that we called agent level, to allow the architect modelling a system in terms of interacting agents. This level of abstraction is not supported by an accepted set of tools and notations yet, even if a number of proposals are available. This paper introduces: (i) An UML-based notation capable of modelling a system at the agent level and (ii) A development framework, called ParADE, exploiting such a notation. The notation we propose is formalized in terms of a UML profile and it supports the realisation of artefacts modelling two basic concepts of the agent level, i.e., the architecture of the multi-agent system and the ontology followed by agents. The choice of formalising our notation in terms of a UML profile allows using it with any off-the-shelf CASE tool. The ParADE framework takes advantage of this choice by providing a code generator capable of producing skeletons of FIPA-compliant agents from XMI files of agent-oriented models. The developer is requested to complete the generated skeletons exploiting the services that ParADE and the underlying agent platform provide.\",\n \"Title: Agent-Based support for open communities\\nYear: 2005\\n\\nAbstract: RAVE (Remote Assistance Virtual Environment) is a Web and multi-agent based system to support remote users during common projects or activities. A Personal Agent, associated with a specific user, helps her/him to solve problems proposing information and answers extracted from some information repositories. It's also able to forward answers received from other on-line users, recommended by their Personal Agents as experts in that specific topic. A profile is built and maintained for each user. A RAVE system is not a closed system, but it's based on a dynamic network of RAVE platforms managing groups of geographically localized users and documents. RAVE users and documents profile management subsystems provide a mechanism that dynamically adapts the relevance of each profile, according to the availability of experts and documents.\",\n \"Title: Service Composition in Open Agent Societies\\nYear: 2003\\n\\nAbstract: Agentcities is a network of FIPA compliant agent platforms that constitute a distributed environment to demonstrate the potential of autonomous agents. One of t he aims of the project is the development of a network ar chitecture to allow the integration of platforms based on different technologies and models. It provides basic white pages an d yellow pages services to allow the dynamic discovery of the hosted agents and the services they offer. An important outcome is the exploitation of the capability of agent-based applic ations to adapt to rapidly evolving environments. This is parti cularly appropriate to dynamic societies where agents act as buyer s and sellers negotiating their goods and services, and composi ng simple services offered by different providers into new compound services.\",\n \"Title: Multi-Agent Corporate Memory Management System\\nYear: 2002\\n\\nAbstract: This paper presents an approach to design a multi-agent system managing a corporate memory in the form of a distributed semantic Web and describes the resulting architecture. The system was designed during the CoMMA European project ( Corporate Memory Management through Agents) and aims at helping users in the management of a corporate memory, facilitating the creation, dissemination, transmission, and reuse of knowledge in an organization. The implementation integrated several emerging technologies: multi-agent system technology ( using the JADE FIPA-compliant platform), knowledge modeling and XML technology for information retrieval ( using the CORESE semantic search engine), and machine learning techniques. Here, we describe the agent roles and interactions, we explain the design rationale for the agent societies, and we discuss the configuration and implementation issues.\",\n \"Title: CAFE - collaborative agents for filtering e-mails\\nYear: 2005\\n\\nAbstract: CAFE (collaborative agents for filtering e-mails) is a multiagent system to collaboratively filter spam from users' mail stream. CAFE associates a proxy agent with each user, and this agent represents a sort of interface between the user's e-mail client (i.e. Microsoft Outlook, Eudora, etc.) and the e-mail server. With the support of other types of agents, the proxy agent makes a classification of new messages into three categories: ham (good messages), spam and spam-presumed. The system analyzes every single e-mail using essentially three kinds of approach: a first approach based on the usage of a hash function, a static approach using DNSBL (DNS-based black lists) databases and a dynamic approach based on a Bayesian algorithm.\",\n \"Title: Agent-Based Virtual Communities for Interactive Digital Television\\nYear: 2006\\n\\nAbstract: This paper describes a multi-agent framework designed to support the creation and effective management of virtual communities in an Interactive Digital Television (IDTV) scenario. The possibiliti es that this framework offers are demonstrated by mean s of two sample applications: a real-time community game and an asynchronous auction. For the sake of completeness, the paper also presents an overview o f IDTV technologies.\",\n \"Title: Intelligent Task Composition and Allocation through Agents\\nYear: 2005\\n\\nAbstract: This paper addresses the need for strong security guarantees in increasingly dynamic and flexible information technology (IT) environments. It applies time-tested security principles, architectural patterns, and continuous improvement constructs to weave ...\",\n \"Title: Developing multi-agent systems with a FIPA-compliant agent framework\\nYear: 2001\\n\\nAbstract: To ease large-scale realization of agent applications there is an urgent need for frameworks, methodologies and toolkits that support the effective development of agent systems. Moreover, since one of the main tasks for which agent systems were invented is the integration between heterogeneous software, independently developed agents should be able to interact successfully. In this paper, we present JADE (Java Agent Development Environment), a software framework to build agent systems for the management of networked information resources in compliance with the FIPA specifications for inter-operable intelligent multi-agent systems. The goal of JADE is to simplify development while ensuring standard compliance through a comprehensive set of system services and agents, JADE can then be considered to be an agent middle-ware that implements an efficient agent platform and supports the development of multi-agent systems. It deals with all the aspects that are not peculiar to agent internals and that are independent of the applications, such as message transport, encoding and parsing, or agent life-cycle management. Copyright (C) 2001 John Wiley & Sons, Ltd.\",\n \"Title: Enhancing peer-to-peer applications with multi-agent systems\\nYear: 2008\\n\\nAbstract: This paper copes with the problem of integrating peer-to-peer and multi-agent systems for the realization of both large-scale multi-agent systems and sophisticated peer-to-peer applications. In particular, it presents how JADE, one of the best known and most used software framework for the development of multi-agent systems, has been extended with a peer-to-peer technology, and how a JADE multi-agent system can be overlapped over a peer-to-peer system to provide more sophisticated services.\",\n \"Title: Cooperative software agents for the Unix domain\\nYear: 1996\\n\\nAbstract: The paper presents an agent architecture that integrates multiple capabilities into a single intelligent agent allowing it to interact both with other agents through an expressive agent communications language and with humans through a human agent interface, and to satisfy external requests either through the direct execution of a set of actions or through a plan defined by an internal planner. This agent architecture has been implemented using a programming environment which takes advantage of object-oriented programming features, and has been experimented with in the Unix domain specializing it to define an agent able to perform a set of Unix commands and to execute actions in cooperation with other agents.\",\n \"Title: Exploiting UML in the Design of Multi-agent Systems\\nYear: 2000\\n\\nAbstract: A basic concept of software engineering is that a system can be described at different levels of abstraction. Agent-oriented software engineering introduces a new level of abstraction, called the agent level, to allow software architects modelling a system in terms of interacting agents. This level of abstraction is not yet supported by an accepted diagrammatic notation even if a number of proposals are available. This work shows how UML can be exploited to model a multi-agent system at the agent level. In particular, it presents a set of agent-oriented diagrams intended to provide an UML-based notation to model: the architecture of the multi-agent system, the ontology followed by agents and the interaction protocols used to co-ordinate agents. The presented notation exploits stereotypes to associate an agent-oriented semantic with class and collaboration diagrams. The benefit of using stereotypes rather than extending UML to provide an agent-oriented semantic is that the presented notation can be used with any off-the-shelf CASE tool.\",\n \"Title: Enhancing information sharing through agents\\nYear: 2006\\n\\nAbstract: This paper presents RAIS, a peer-to-peer multi-agent system for information sharing among a community of users connected through the Internet. RAIS offers a similar search power of Web search engines, but avoids the burden of publishing information on the Web and guarantees a controlled and dynamic access to information. The use of agent technologies has made straightforward the realization of three of the main features of the system: i) filtering of information coming from different users, on the basis of the previous experience of the local user, ii) pushing of new information that can be of interest for a user, and iii) delegation of access capabilities, on the basis of a reputation network, built by the agents of the system on the community of its users.\",\n \"Title: Security and Trust in Agent-Oriented Middleware\\nYear: 2003\\n\\nAbstract: Spreading of technologies as peer-to-peer networks, web services, multi-agent systems, ubiquitous computing, shows a clear trend toward open and highly distributed systems, requiring wide and dynamic overlay networks. But mass adoption of these technologies, especially in contexts where sensible resources are handled, will come true only if they will be able to guarantee a proper level of security. This paper presents the implementation of a security layer for JADE, a standard-based and widely deployed framework to build multi-agent systems. The proposed model, founded on delegation certificates, allows the management of trust relations among autonomous software agents collaborating and competing in wide and open agent societies, but it is also used to protect the underlying distributed infrastructure, providing required resources and services to hosted agents. Our approach, where policies are based on keys instead of names, enhances robustness and scalability by greatly reducing the impact of certificate directory unavailability on the authorization mechanism.\",\n \"Title: A Contract Decommitment Protocol for Automated Negotiation in Time Variant Environments\\nYear: 2001\\n\\nAbstract: Negotiation is a fundamental mechanism in distributed multi-agent systems. Since negotiation is a time-spending process, in many scenarios agents have to take into account the passage of time and to react to uncertain events. The possibility to decommit from a contract is considered a powerful technique to manage this aspect. This paper considers interactions among self-interested and autonomous agent, each with their own utility function, and focuses on incomplete information. We define a negotiation model based on asynchronous message passing in which the negotiation doesn't end when an agreement is reached but when the consequences of the contract have happened - i.e. the action is done. In this model the agent utility functions are time dependent. We present an extension of the contract net protocol that implements the model.\",\n \"Title: Developing Smart Emergency Applications with Multi-Agent Systems\\nYear: 2010\\n\\nAbstract: Multi-agent systems have been importantly contributing to the development of the theory and the practice of complex distributed systems and, in particular, they have shown their potential to meet critical needs in high-speed, mission-critical, content-rich, distributed information applications where mutual interdependencies, dynamic environments, uncertainty, and sophisticated control play a remarkable role. Therefore, multi-agent systems are considered a suitable technology for the realization of e-health applications where the use of loosely coupled and heterogeneous components, the dynamic and distributed management of data, and the remote collaboration among users are often the most relevant requirements. This paper describes some of the main reasons why multi-agent systems are today considered one of the best technologies for the realization and deployment of advances for e-health applications and, in particular, of smart emergency applications. After an introduction on the inherent characteristics of the use of multi-agent systems for e-health, the paper presents the results of EU-scale project CASCOM: a real multi-agent system for the execution of smart emergency tasks.\",\n \"Title: A Portal for Ubiquitous Collaboration\\nYear: 2003\\n\\nAbstract: This paper presents a software framework, called Collaborator, to provide a shared work-space supporting the activities of virtual teams. This sys- tem exploits seamless integration of standar d Web technologies with agent technologies, enhancing the classic Web communication mechanisms to su p- port synchronous sharing of applic ations, and its use through emerging tech- nologies such as: third generation of mobile networks and terminals, and new generation of home appliances. The system presented in the paper is the main result of an on-going European research project Collaborator (IST-2000-30045) that aims at specifying and developing a software distributed environment to support efficient synchronous collaborative work between virtual teams, and experiment such an environment in the construction and telecommunication working sectors\",\n \"Title: A collaborative platform for fixed and mobile networks\\nYear: 2002\\n\\nAbstract: C/Webtop: providing users with a means for collaborating while on the move.\",\n \"Title: Adding extensible synchronization capabilities to the agent model of a FIPA-compliant agent platform\\nYear: 2000\\n\\nAbstract: In this paper, we present an agent platform, called JADE (Java Agent Development Environment), that tries to ease development applications in compliance with the FIPA specifications. Moreover, we describe an extension to JADE original agent model that allows expressing agent synchronisation constraints better and provides wider foundations to build higher-level agent architecture on. JADE agent model is more \\\"primitive\\\" than the agent models offered by other systems, and mainly deals with message handling and plan scheduling. Exploiting research results about concurrent OO languages, JADE agent model has been extended in a way that solves the inheritance anomaly problem and will be useful to JADE users when they will create more complex agents.\",\n \"Title: Open Social Networking for Online Collaboration\\nYear: 2013\\n\\nAbstract: Features of online social networks are being introduced in various applications and environments, including tools supporting virtual teams and online collaboration in general. In fact, social networking has a large potential for easing collaboration, also across organizational boundaries. However, effective e-collaboration through social networks requires the development of open and interoperable systems, allowing people belonging to different organizations to create ties, reflecting real connections existing in daily activities. Attention has to be paid to identity management, for allowing users to develop their reputation consistently, and to privacy and confidentiality, for creating a more trustful environment and protecting freedom of expression. In this article, the authors propose a novel peer-to-peer system, named Blogracy, leveraging the large BitTorrent network. Its main distinguishing features are: i protection of users' identity and privacy, ii absence of central control over published content; iii interoperability with other systems; and iv low costs and scalability of the infrastructure.\",\n \"Title: Enabling Vocal Interaction in a Web Portal Environment.\\nYear: 2006\\n\\nAbstract: The growing request of innovative, multimodal interfaces for mobile users and the need of different navigation paradigms for impaired Internet users are promoting and driving nowadays research on multimodal interactions. In this paper we present our experiences in the integration of vocal components in a portal engine, namely Apache Jetspeed. First, we discuss the reasons why the integration of a full-featured portal brings significant advantages to the development of a vocal platform. Then, we describe two complementary approaches for enhancing portals with vocal capabilities, and we compare them under various standpoints. The first approach that we investigate is based on a server-side speech synthesizer, while the second relies on client-side technologies, X+V and the SALT markup languages. For each of these approaches we present some examples and we discuss advantages and drawbacks.\",\n \"Title: An ontology support for semantic aware agents\\nYear: 2005\\n\\nAbstract: The work presented in this paper is an attempt to bridge two co-existing realties: Semantic Web and Multi-Agent Systems. Semantic aware agents will be able to interoperate in a semantic way as well as to produce and consume semantically annotated information and services. Agents should be enhanced with tools and mechanisms in order to autonomously achieve these strategic and ambitious objectives. In this paper, we focus on what we consider the central issue when moving towards the vision of semantic multi-agent systems: the ontology management support. Due to the heterogeneity of resources available and roles played by different agents of a system, a one-level approach with the aim of being omni comprehensive seems to be seldom feasible. In our opinion, a good compromise is represented by a two-level approach: a light ontology management support embedded in each agent and one or more ontology servers, providing a more expressive and powerful support.\",\n \"Title: Low Cost Databases for NOW\\nYear: 1999\\n\\nAbstract: . In this paper, we present a system called DONOW (Databaseon Network of Workstation), that is an example of an implementationand maintenance of a low cost distributed database without performancespenalties. The system has a three tier architecture based on aclient, a service and a data layer. The client layer allows local and remoteusers to interact with the system through a Java user friendly interface.The service layer is implemented in C++; it allows the service of userrequests and,...\",\n \"Title: Agent-based interpretations of classic network models\\nYear: 2013\\n\\nAbstract: The paper is aimed at developing agent-based variants of traditional network models that make full use of concurrency. First, we review some classic models of the static structure of complex networks with the objective of developing agent-based models suited for simulating a large-scale, technology-enabled social network. Secondly, we outline the basic properties that characterize such networks. Then, we briefly discuss some classic network models and the properties of the networks they generate. Finally, we discuss how such models can be converted into agent-based models (i) to be executed more easily in heavily concurrent environments and (ii) to serve as basic blocks for more complex agent-based models. We evidence that many implicit assumptions made by traditional models regarding their execution environment are too expensive or outright impossible to maintain in concurrent environments. Consequently, we present the concurrency issues resulting from the violation of such assumptions. Then, we experimentally show that, under reasonable hypothesis, the agent-based variants maintain the main features of the classic models, notwithstanding the change of environment. Eventually, we present a meta-model that we singled out from the individual classic models and that we used to simplify the agent-oriented conversion of the traditional models. Finally, we discuss the software tools that we built to run the agent-based simulations.\",\n \"Title: JADE: a FIPA2000 compliant agent development environment\\nYear: 2001\\n\\nAbstract: JADE (Java Agent Development Framework) is a software environment to build agent systems for the management of networked information resources in compliance with the FIPA2000 specifications for interoperable intelligent multi- agent systems. The goal of JADE is to simplify development while ensuring standard compliance through a comprehensive set of system services and agents. JADE offers an agent runtime system on which implement efficient FIPA 2000 compliant multi- agent systems and supports their development through the availability of a predefined programmable agent model and of a set of management and testing tools. This paper describes the main features of the JADE system and introduces some of the most important projects based on JADE software.\",\n \"Title: Developing Multi-agent Systems with JADE\\nYear: 2000\\n\\nAbstract: JADE (Java Agent Development Framework) is a software framework to make easy the development of multi-agent applications in compliance with the FIPA specifications. JADE can then be considered a middle-ware that implements an efficient agent platform and supports the development of multi agent systems. JADE agent platform tries to keep high the performance of a distributed agent system implemented with the Java language. In particular, its communication architecture tries to offer flexible and efficient messaging, transparently choosing the best transport available and leveraging state-of-the-art distributed object technology embedded within Java runtime environment. JADE uses an agent model and Java implementation that allow good runtime efficiency, software reuse, agent mobility and the realization of different agent architectures.\",\n \"Title: Using PVM to develop a distributed object-oriented language for heterogeneous processing\\nYear: 1998\\n\\nAbstract: This paper presents an object-oriented distributed language, called PVOOL, that is a good tool for developing real distributed applications. PVOOL is based on active objects called pv_units and concurrent message passing among them. The main feature of PVOOL is the possibility to coordinate the activity of different pv_units through virtual circuits. Virtual circuits are objects that indicate what are the operations to be performed, what are the pv_units that must do them, and what is the order in which they must be done to give a certain task. Virtual circuits can be dynamically created by pv_units and so this distributed object-oriented system can change its behavior during its life. PVOOL takes advantage of PVM procedures to perform objects distribution and message exchange, without explicitly writing low-level code. The use of PVM allows an easily distribution of a program, that is of its objects, on a heterogeneous network of parallel and serial computers. In particular, the paper describes how the features offered by PVOOL were useful to implement a flexible environment for the development of computer vision applications.\",\n \"Title: A Multi Language Environment to Develop Multi Agent Applications\\nYear: 1996\\n\\nAbstract: HOMAGE is an environment for the development of multi agent systems integrating agent and object-oriented programming paradigms and offering two different programming levels: object and agent. The object level allows the use of three object-oriented programming languages (C++, Common Lisp and Java) to develop new agent models as well as the components that will be used to build the body of agents. The agent level allows the development of new agents by defining their brain and by composing the components defined at the object level, and allows the development of multi agent systems by distributing and interconnecting agent instances. Moreover, these multi agent systems can be distributed on a net of heterogeneous machines connected through internet taking advantage of a set of communication and distribution libraries allowing the communication between agents through different protocols. The paper includes a brief description of a robotic application that we implemented during the experimentation of the environment.\",\n \"Title: A security infrastructure for trust management in multi-agent systems\\nYear: 2004\\n\\nAbstract: Multi-agent systems are based on the interaction of autonomous software components, the agents, which cooperate to achieve common goals. But such interactions, just as in human societies, can be set correctly only on the base of trust relations. This paper presents a security model founded on delegation certificates, which allows the management of security policies on the base of trust relations among autonomous software agents, collaborating and competing in wide, open and evolving agent societies. On the converse, the presence of a strong and flexible security infrastructure is fundamental to develop trust in counterparts and start advantageous interactions with them. While some of these concepts are already being adopted into the development of the security layer for JADE, a standard-based and widely deployed framework to build multi-agent systems, this paper includes further ideas which distributed multi-agent security frameworks could benefit from.\",\n \"Title: A Distributed Object-Oriented Language for Heterogeneous Computer Networks\\nYear: 1999\\n\\nAbstract: This paper presents an object-oriented distributed language, called CUBL++, that is a powerful tool for developing distributed applications on heterogeneous computer networks. CUBL++ is based on objects, called c_units, that communicate through synchronous and asynchronous message passing. A c_unit is an active object composed of data (state) and procedures as traditional (passive) objects, together with the capability of queueing incoming messages, when needed. C_units allow a programmer to implement an application on a heterogeneous architecture, as they communicate with each other without taking into account the physical characteristics of the actual node where they are located. We have experimented CUBL++ on a network where UNIX workstations, WindowsNT personal computers and transputers cooperate in order to perform a given task. In particular, this paper gives a brief description of a distributed system for image processing that has been implemented by using CUBL++.\",\n \"Title: Multi-User and Security Support for Multi-Agent Systems\\nYear: 2001\\n\\nAbstract: This paper discusses the requirements an agent system needs to be secure. In particular, the paper introduces a classification of modern distributed systems, and examines the delegation concept from a security point of view. After discussing the peculiar security and delegation issues present in distributed object systems, mobile agent systems and in multi agent systems, a case study is presented, describing the multi-user and security support that is being built into the JADE platform.\",\n \"Title: ANEMONE - A Network of Multi-Agent Platforms for Academic Communities\\nYear: 2005\\n\\nAbstract: This paper presents ANEMONE, a multi-agent platforms network that provides services for the academic community implemented by using the JADE agent development framework. In particular, ANEMONE provides a set of services to support i) academic people in some of their recurrent activities (fix an appointment, organize a meeting and search documents on the Web, ii) students in getting information about courses and iii) information technology people (including students) in getting information on documents and people that may help them to solve their programming problems. Moreover, it also provides a set of system-oriented services for the management of agent platforms and services and for the realization of new types of service.\",\n \"Title: Mpool: An Object-Oriented Library For Task Composition And Co-Ordination\\nYear: 1999\\n\\nAbstract: MPOOL is an object-oriented extension to the MPI library, based on three categories of objects, called units, groups and schemes. Units are active objects composed of data (state) and procedures (like traditional passive objects), but with the additional ability to store incoming messages in a queue while they are active and to send messages in parallel to other units; moreover, different units may be active simultaneously. Groups and schemes are passive objects used for the composition of units and the co-ordination of their actions, Groups manage collective communications and synchronization operations such as barriers. Schemes compose units' actions through the use of a set of constructs derived by path expressions.\",\n \"Title: CoMMA: a multi-agent system for corporate memory management\\nYear: 2002\\n\\nAbstract: In this paper, we present CoMMA (Corporate Memory Management through Agents), an open, agent-based system for the management of a corporate memory that was realized integrating several emerging technologies: agent technology, knowledge modeling, XML technology, information retrieval and machine learning techniques. In particular, the system has been realized to help users in the management of an organization corporate memory and in particular to facilitate the creation, dissemination, transmission and reuse of knowledge in an organization. CoMMA system is a FIPA compliant agent system and has been implemented by using the JADE agent development software framework. CoMMA is the result of an international project funded by European Commission.\",\n \"Title: An object-oriented language for distributed artificial intelligence\\nYear: 1993\\n\\nAbstract: In this work, we are presenting an object-oriented language to define distributed artificial intelligence (DAI) systems. This language allows for the description of control and communication management, a hierarchical representation of a DAI system at different levels of detail, and the simulation of its performance.\",\n \"Title: Developing Real Applications With Agent Technologies.\\nYear: 1999\\n\\nAbstract: In this paper, we present an agent library to develop multi-agent applications. Such an agent library has been realised taking into account FIPA specifications. FIPA specifications give the minimum amount of technology deemed necessary for the management of agents in an open agent system, including agent roles, an agent communication language, an agent management content language, and a standard way to interact with non-agentised software.\",\n \"Title: What Agent Middleware Can (And Should) Do For You\\nYear: 2002\\n\\nAbstract: This paper addresses the issue of moving agent technology to the mainstream, looking from various perspectives at the mainstreaming process that can take place during a technology life cycle, radically moving its status from a supposedly good idea to an actual economic and industrial workhorse that lends itself useful in everyday life. While there is serious evidence that agent technology is approaching this critical point, it is by no means possible to tell whether agent technology will eventually be adopted on a global scale or not. However, looking at the various factors that can make the difference between acceptance and oblivion, a mainstreaming strategy can be set up. We claim that agent middleware has to play a fundamental role in this strategy, and we motivate our belief on the basis of general considerations and on our actual experience with the JADE agent platform.\",\n \"Title: MAP - a Language for the Modelling of Multi-Agent Systems\\nYear: 1993\\n\\nAbstract: This paper presents a distributed object-oriented language, called Multi-Agent Programming language, whose features are suitable to develop multi-agent systems. This language is based on an object, called agent, (i) performing private actions, (ii) communicating with other agents, and (iii) re-configuring system structure through the creation of other agents and changing its behaviour. The main feature of this language is the use of a large set of communication primitives, defined on the spirit of Speech Act theory, which are suitable to model agent interactions and which can be specialised to implement specific communication protocols. In particular, the paper shows how these primitives are suitable to model negotiation protocols.\",\n \"Title: Automatic Storing and Retrieval of Large Collections of Images\\nYear: 1998\\n\\nAbstract: This paper, presents a system, SISTER, that is suitable for storing and retrieve of large collections of images allowing the user to formulate queries for different image categories on the basis of color information and specific attributes of the image category; this is possible, because SISTER can be easily adapted to support new image categories specializing the acquisition and the retrieval subsystems. SISTER is composed of three parts: i) an image acquisition subsystem automatically extracting the attributes from images, ii) a database management subsystem maintaining the descriptions of images, and iii) a retrieval subsystem allowing the user to retrieve images through a user-friendly graphical interface. The acquisition subsystem extracts image attributes combining image processing and inductive classification modules. Classification modules are useful because they may allow the extraction of attributes that cannot be extracted through image processing techniques and because they may allow the reduction of the error percentage made by the image processing modules in the acquisition of image attributes.\",\n \"Title: Implementation Level Issues in MAS Modeling.\\nYear: 2003\\n\\nAbstract: Abstract - The aim of this paper is to focus on the issues connected with the diagrammatic notations and tools, which should support developers when moving from the design phase towards the implementation phase of MASs The paper deals with three main research lines: the representation of the inter - actions between agents and their relationship with the internal architecture of the single agent, the deployment of MASs, and the pattern reuse\",\n \"Title: An efficient and flexible C++ library for concurrent programming\\nYear: 1998\\n\\nAbstract: A major problem for the integration of concurrency in object-oriented languages is the so-called inheritance anomaly, i.e. the conflicts between inheritance and concurrency that often cause the need to redefine inherited methods in order to maintain the integrity of objects. Several solutions have been proposed for resolving these conflicts. However, some of them are incomplete, and do not solve all types of inheritance anomaly; others make the definition of classes complex and/or their implementation inefficient. This paper describes a C++ library for concurrent programming that provides a comprehensive framework particularly suitable for coarse-grained distributed applications. This library copes with the inheritance anomaly problem, presenting a solution that minimizes the redefinition of inherited methods without increasing the complexity to write them. This solution is based on the use of a special set of methods, called interface methods, composed of a body and two sets of synchronization constraints. These two sets of synchronization constraints are respectively used to enable the execution of their method body and to disable the methods that cannot be executed after their method. (C) 1998 John Wiley & Sons, Ltd.\",\n \"Title: A Multi-Agent Framework to Join DTV and Virtual Communities\\nYear: 2006\\n\\nAbstract: In this paper present a multi-agent framework for integrating the emergent technology of the interactive digital television with new types of services to support the cooperative activities of different types of virtual communities. As an example of such kind of service we present a community game, in which we have a real-time interaction between two DTV users, and an online auction, in which although the interaction is asynchronous.\",\n \"Title: JADE: A software framework for developing multi-agent applications. Lessons learned\\nYear: 2008\\n\\nAbstract: Since a number of years agent technology is considered one of the most innovative technologies for the development of distributed software systems. While not yet a mainstream approach in software engineering at large, a lot of work on agent technology has been done, many research results and applications have been presented, and some software products exists which have moved from the research community to the industrial community. One of these is JADE, a software framework that facilitates development of interoperable intelligent multi-agent systems and that is distributed under an Open Source License. JADE is a very mature product, used by a heterogeneous community of users both in research activities and in industrial applications. This paper presents JADE and its technological components together with a discussion of the possible reasons for its success and lessons learned from the somewhat detached perspective possible nine years after its inception.\",\n \"Title: A development toolkit to realize autonomous and interoperable agents\\nYear: 2001\\n\\nAbstract: Autonomy and inter- operability are two characteristics of software agents that are advocating agent technology as an ideal candidate to support next generation of software systems. This paper presents a Java development toolkit supporting the realization of autonomous and inter- operable agents. This toolkit provides the developer with a goal- oriented agent architecture for FIPAcompliant agents. Goal- orientation supports autonomy because the developer is no longer requested to describe what the agent should do in reaction to events. To this extent, our development toolkit provides a planning engine capable of building plans to achieve the agents goals autonomously. Goal- orientation is also a key aspect of inter- operability because it is the basis of the semantics of FIPA ACL. Our development toolkit can be used at two levels of abstraction. The higher level, that we call the agent level, allows describing the agent in terms of its natural characteristics such as goals, beliefs and social organization. A code generator producing Java skeletons from UML diagrams supports this level. The developer can choose any UML CASE tool to model her agents because this code generator works with files in a standard format. The generated skeletons must be completed with application- specific code at the lower level of abstraction, that we call object level. At this level, agents are seen as Java programs and the developer is provided with a development library to integrate her code within the generated skeletons. This two- level approach allows describing agents in their natural terms at the agent level, while supporting the integration of application- specific and legacy code at the object level. Moreover, the generated code can be customized at the object level to integrate application- specific optimizations.\",\n \"Title: Dynamic Grid Tasks Composition And Distribution Through Agents\\nYear: 2006\\n\\nAbstract: This paper presents a multi-agent system called GAIN (Grid Agent Infrastructure), which can be used for the development of flexible agent-based Grid systems. The system supports users both in the development and execution of Grid applications. In particular, GAIN allows the definition of workflow applications by composing different tasks made available by the Grid nodes. Furthermore, it follows the different phases of the execution of the workflow providing transparent allocation and re-allocation of the tasks on the different nodes of the Grid. A first prototype of the system has been realized by using the JADE agent development software and it has been tested in lab trials involving a network of different JADE platforms. In these trials, tasks provided both by the agents of the system and by external legacy software systems have been composed. Copyright (c) 2005 John Wiley & Sons, Ltd.\",\n \"Title: An agent-based approach to manage negotiation protocols in flexible CSCW systems\\nYear: 2000\\n\\nAbstract: Autonomous agents are often used to manage the complex situations arising in computer-supported collaborative activities. Anyway, agents are confined to accomplish only marginal tasks and cannot yet be considered integrated with CSCW systems. This paper describes CollAge, an agent-based CSCW system designed to promote the productivity of distributed meetings by means of agents. The system architecture assigns a personal agent to every meeting attendant and includes a project-manager agent and a resource-manager agent to deal with the activities related to arranging and managing the meetings.\",\n \"Title: Janet: A Framework For Flexible Web-Content Retrieval\\nYear: 2000\\n\\nAbstract: Quality-of-service negotiation is considered a fundamental step in the provision of multimedia content especially when only a low-bandwidth channel is available. The widespread adoption of the Web by home users and the increasing complexity of Web pages suggest to extend the existing negotiation protocols to generic Web contents. This should increase the flexibility of current document retrieval systems and should also help to manage the needs of users connecting through low-bandwidth channels. This paper describes how a quality-of-service can be associated with a generic Web content and presents a development framework that supports negotiation as a means to enhance flexibility in the retrieval of Web contents.\",\n \"Title: Information Attacks on Online Social Networks\\nYear: 2014\\n\\nAbstract: Online social networks have changed the way people interact, allowing them to stay in touch with their acquaintances, reconnect with old friends, and establish new relationships with other people based on hobbies, interests, and friendship circles. Unfortunately, the regrettable concurrence of the users' carefree attitude in sharing information, the often sub-par security measures from the part of the system operators and, eventually, the high value of the published information make online social networks an interesting target for crackers and scammers alike. The information contained can be used to trigger attacks to even more sensible targets and the ultimate goal of sociability shared by the users allows sophisticated forms of social engineering inside the system. This work reviews some typical social attacks that are conducted on social networking systems, carrying real-world examples of such violations and analysing in particular the weakness of password mechanisms. It then presents some solutions that could improve the overall security of the systems.\",\n \"Title: Supporting Social Networks with Agents\\nYear: 2014\\n\\nAbstract: Multi-agent systems have been contributing to the development of both theory and practice of complex distributed systems. Social networks are probably the systems that exhibit the highest degree of similarity with multi-agent systems because members of a social network interact as agents do in a multi-agent system. Multi-agent system may be the best solution to enrich and facilitate the interaction and the collaboration among the members of a social network. After an introduction on the relationships between multi-agent systems and social networks, this paper describes Blogracy, a multi-agent system that supports the interaction among the members of a social network.\",\n \"Title: Representing real world phenomena through HDPTN\\nYear: 1991\\n\\nAbstract: The authors present a model, called HDPTN (hierarchical and distributed process transition network), for the representation of real world phenomena. This model is based on two types of entities: circumstances and episodes. A circumstance is an elementary entity which can take on a set of discrete values over time, while an episode is a compound entity whose parts are a circumstance and/or other episodes acting concurrently. In particular, the hierarchical and distributed structure of the episode seems to be suitable for the modeling of systems which need real-time performance and the integration of representations and reasoning at different levels of detail\",\n \"Title: Ontology based automatic speech recognition and generation for human-agent interaction\\nYear: 2004\\n\\nAbstract: In this paper, we present a system that supports an automatic speech recognition and generation between users and an agent based application on the basis of the ontologies used in the application domain. The system is realized taking advantage of the JADE agent development framework and of the IBM Via Voice Tool and has been experimented in different applications fields testing agent - user interaction both in Italian and English. In particular, the paper introduces a short description of the use of the system for banking applications.\",\n \"Title: Supporting cooperation with off-the-shelf applications in wired and wireless networks\\nYear: 2001\\n\\nAbstract: This paper presents a cooperative platform that allows the sharing of information as well as the interactive use of different kinds of application in a synchronous mode. The access to the collaborative sessions is possible from different kinds of terminal and network (fixed or mobile). In particular, we address Web users and mobile users with sufficient bandwidth. The platform is based on the centralised sharing of an off-the-shelf application that relies on a collaborative version of the graphics libraries used in Java and Microsoft Windows. A first prototype of the platform has been experimented by Ph.D. students during a seminar distributed across Italy\",\n \"Title: Agent-based Social Networks for Enterprise Collaboration\\nYear: 2011\\n\\nAbstract: This paper discusses the relationship between agent technology and the recent wave of online social networks in the scope of the notable scenario of enterprise collaboration. In the brief introduction on the topic, we provide a coherent view of online social networks and social network systems. Then, we emphasize some features that can be considered as notable flaws that make everyday social networks and systems unusable to facilitate enterprise collaboration. Finally, we show how agent technology can address some of the mentioned flaws. The paper terminates with some concluding remarks and with an outline of future research directions.\",\n \"Title: An Outline Of The Use Of Transition Systems To Formalize Jade Agents And Multi-Agent Systems\\nYear: 2015\\n\\nAbstract: This paper presents the key aspects of a proposed formalization of JADE agents and multi-agent systems based on transition systems. Such a formalization is meant to be useful to describe and clarify how JADE multi-agent systems work and to provide a theoretical instrument to validate and analyze the semantics of JADE agents. This is needed to decouple agent-oriented and object-oriented parts of an agent design and to avoid misunderstandings on the semantics of JADE agents. The chosen approach is to define a structural operational semantics for Java programs written using JADE, and the proposed formalization consists in two parts: the first identifies and defines the main entities that together compose a JADE multi-agent system; the second provides the transition system and rewriting rules. The paper terminates with two explanatory examples of the usage of the transition system. A brief recapitulation of the work concludes the paper.\",\n \"Title: Information and Password Attacks on Social Networks: An Argument for Cryptography\\nYear: 2015\\n\\nAbstract: Online social networks have changed the way people interact, allowing them to stay in touch with their acquaintances, reconnect with old friends, and establish new relationships with other people based on hobbies, interests, and friendship circles. Unfortunately, the regrettable concurrence of the users' carefree attitude in sharing information, the often sub-par security measures from the part of the system operators and, eventually, the high value of the published information make online social networks an interesting target for crackers and scammers alike. The information contained can be used to trigger attacks to even more sensible targets and the ultimate goal of sociability shared by the users allows sophisticated forms of social engineering inside the system. This work reviews some typical social attacks that are conducted on social networking systems, carrying real-world examples of such violations and analysing in particular the weakness of password mechanisms. It then presents some solutions that could improve the overall security of the systems.\",\n \"Title: Social Media for Online Collaboration in Firms and Organizations\\nYear: 2016\\n\\nAbstract: AbstractParticipation in social networks has long been studied as a social phenomenon according to different theories. In particular, the notion of social capital highlights a person's benefit due to his relations with other persons, including family, colleagues, friends and generic contacts. It may be important both for the individuals that are able to accumulate large amounts, and for organizations. Nowadays, social networking systems bring many acquaintances online, both in the private and working spheres. Some systems are used both at home, for leisure goals, and on the work place, professionally. In the vast majority of cases, social networking platforms are still used without corporate blessing. However, several traditional information systems, such as CRMs and ERPs, have also been modified in order to include social aspects. This article shows the role of social capital in the participation in online social networking activities, in the various cases of Virtual Organizations, Virtual Teams, and online Networks of Practice. It describes the present situation, which is characterized by great promises and mixed initial results, and some possible prospects.\",\n \"Title: Blogracy: A Peer-to-Peer Social Network\\nYear: 2016\\n\\nAbstract: AbstractThe current approach to build social networking systems is to create huge centralized systems owned by a single company. However, such strategy has many drawbacks, e.g., lack of privacy, lack of anonymity, risks of censorship and operating costs. In this paper the authors propose a novel P2P system that leverages existing, widespread and stable technologies such as DHTs and BitTorrent. In particular, they introduce a key-based identity system and a model of social relations for distributing content efficiently among interested readers. The system they propose, Blogracy, is a micro-blogging social networking system focused on: i anonymity and resilience to censorship; ii authenticatable content; iii semantic interoperability using activity streams. The authors have implemented the system and conducted various experiments to study its behaviour. The results are presented here, regarding i communication delays for some simulations of node churn, ii delays measured in test operations over PlanetLab, in direct communication, and iii through the I2P anonymizing network.\",\n \"Title: Core Features of an Agent-Oriented Domain-Specific Language for JADE Agents.\\nYear: 2016\\n\\nAbstract: This paper presents the core features of JADEL, an agent-oriented domain-specific programming language for the construction of JADE agents, behaviours and ontologies. The work on JADEL originates from the need to assist programmers by means of tools that reduce the complexity and speed up the construction of a JADE agents and multi-agent systems. The features of JADEL discussed in this paper include abstractions for the main entities of JADE-agents, behaviours and ontologies-and they also encompass the features needed for the construction of domain-specific tasks, thus enriching JADE APIs with novel and simple notations.\",\n \"Title: Interaction protocols in the JADEL programming language.\\nYear: 2016\\n\\nAbstract: This paper presents the support for interaction protocols that has been recently added to the JADEL programming language. JADEL is an agent-oriented programming language designed to ease the development of JADE agents and multi-agent systems by offering general-purpose agent-oriented abstractions to the programmer. The first part of the paper presents JADEL and motivates the need for a new agent-oriented programming language. Then, the agent-oriented abstractions that JADEL has been providing since its first version-namely agents, behaviours and communication ontologies-are described. The new support for interaction protocols is finally presented, and a simple example of a JADEL multi-agent system that uses interaction protocols is reported. The paper is concluded with an overview of the current state of JADEL and related tools.\",\n \"Title: A Comparison between Asynchronous Backtracking Pseudocode and its JADEL Implementation.\\nYear: 2017\\n\\nAbstract: In this paper, a comparison between the pseudocode of a well-known algorithm for solving distributed constraint satisfaction problems and the implementation of such an algorithm in JADEL is given. First, background and motivations behind JADEL development are illustrated. Then, we make a description of the problem and a brief introduction to JADEL. The core of this work consists in the translation of the algorithm pseudocode in JADEL code, which is described in details. Scope of the paper is to evaluate such a translation, in terms of closeness to pseudocode, complexity, amount of code written and performance.\",\n \"Title: Preserving Privacy in a P2P Social Network.\\nYear: 2016\\n\\nAbstract: Building centralized social networking systems has many drawbacks, e.g., lack of privacy, lack of anonymity, risks of censorship, and operating costs. As it is discussed in this article, an alternative approach is possible. A prototype system, named Blogracy, has been realized as a micro-blogging social networking system, based on well-known P2P technologies, such as DHTs and BitTorrent. In particular, this article presents the security architecture of the system, which relies on a key-based identity system and a scheme for attribute-based content encryption, with multiple authorities. Moreover, some empirical results obtained in test operations over PlanetLab are presented, comparing plain and I2P anonymized communications.\",\n \"Title: Agent-oriented model-driven development for JADE with the JADEL programming language.\\nYear: 2017\\n\\nAbstract: This paper describes, from motivations and main objectives to actual implementation, a novel agent-oriented programming language called JADEL. JADEL is designed to support the effective implementation of JADE agents and multi-agent systems in the scope of real-world model-driven development because it concretely helps developers by natively supporting agent-oriented abstractions, and because it is based on mature industrial-strength technologies. The four core abstractions that JADEL supports, namely agents, behaviours, communication ontologies, and interaction protocols, are presented by gradually introducing the specific syntaxes that the language provides for them. In the last part of the paper, a complete example of a simple JADEL multi-agent system is presented and discussed. Such an example is a well-known example from the official distribution of JADE and many programmers learned the basics of JADE from it. The choice of this example allows comparing JADEL source code with reference Java source code using JADE, and it clearly emphasizes the practical advantages of agent-oriented programming.\",\n \"Title: Automatic Creation of a Large and Polished Training Set for Sentiment Analysis on Twitter.\\nYear: 2017\\n\\nAbstract: Within the field of sentiment analysis and emotion detection applied to tweets, one of the main problems related to the construction of an automatic classifier is the lack of suitable training sets. Considering the tediousness of manually annotating a training set, and the noise present in data collected directly from the social web, in this paper we propose an iterative learning approach, which combines distant supervision with dataset pruning techinque. In particular, following the \\\"eat your own dogfood\\\" idea, we have applied a classifier, trained on raw data obtained from different Twitter channels, to the same original dataset, for removing the most doubious instances automatically. This kind of approach has been used to obtain a more polished training set for emotion classification, based on Parrot's model of six basic emotions. On the basis of the achieved results, we argue that the automatic filtering of training sets can make the application of the distant supervision approach more effective in many use cases.\",\n \"Title: Actors Based Agent Modelling and Simulation.\\nYear: 2018\\n\\nAbstract: Agent-based modeling and simulation are some powerful techniques that are widely used with success for analyzing complex and emergent phenomena in many research and application areas. Many different reasons are behind the success of such techniques, among which an important mention goes to the availability of a great variety of software tools, that ease the development of models, as well as the execution of simulations and the analysis of results. However, the agent models provided by such tools do not offer the features of the computational agents found in multi-agent systems or distributed artificial intelligence techniques. Therefore, it is difficult to use such tools to model complex systems defined by autonomous, proactive and social entities. This paper presents an actor software library, called ActoDeS, for the development of concurrent and distributed systems, and shows how it can be a suitable mean for building flexible and scalable ABMS applications.\",\n \"Title: A holistic system for troll detection on Twitter.\\nYear: 2018\\n\\nAbstract: Various techniques based on artificial intelligence have been proposed for the automatic detection of online anti-social behaviors, both in existing systems and in the scientific literature. In this article, we describe TrollPacifier, a holistic system for troll detection, which analyses many different features of trolls and legitimate users on the popular Twitter platform. In this system, the most known and promising approaches and research lines are applied, along with original new ideas, in a form that fits such a large public platform. In particular, we have identified six groups of features, based respectively on the analysis of writing style, sentiment, behaviors, social interactions, linked media, and publication time. As its main scientific contributions, this work provides: (i) an up-to-date analysis of the state of the art for the problem of troll detection; (ii) the systematic collection and grouping of features, on Twitter; (iii) the description of a working holistic system for troll detection, with a very high accuracy (95.5%); and (iv) a comparison among the different features, with a machine learning approach. Our results demonstrate that automatic classification can be useful in the whole process of identification and management of online anti-social behaviors. However, a multi-faceted approach is required, in order to obtain an adequate accuracy.\",\n \"Title: A Week of Playing with Code, the Object-Oriented Way.\\nYear: 2018\\n\\nAbstract: This work presents the results of some summer stages for high school students, for the first introduction to computational thinking and programming. Differently from other approaches, our experiences are characterized by: (i) a full week of lessons and exercises, for gradually developing a small but complete and original project, (ii) an objects-early methodology, (iii) the choice of a dynamic videogame as the main programming project, and (iv) the availability of few small and focused examples, as source files, for students to start building their own application. At the end, the students' anonymous opinions about the stage, and their own projects, were collected and analyzed, for improving future similar activities.\",\n \"Title: A Multi-Agent Architecture for Data Analysis.\\nYear: 2019\\n\\nAbstract: ActoDatA (Actor Data Analysis) is an actor-based software library for the development of distributed data mining applications. It provides a multi-agent architecture with a set of predefined and configurable agents performing the typical tasks of data mining applications. In particular, its architecture can manage different users' applications; it maintains a high level of execution quality by distributing the agents of the applications on a dynamic set of computational nodes. Moreover, it provides reports about the analysis results and the collected data, which can be accessed through either a web browser or a dedicated mobile APP. After an introduction about the actor model and the software framework used for implementing the software library, this article underlines the main features of ActoDatA and presents its experimentation in some well-known data analysis domains.\",\n \"Title: Island model in ActoDatA: an actor-based implementation of a classical distributed evolutionary computation paradigm\\nYear: 2021\\n\\nAbstract: ABSTRACTIn this paper, we make a first assessment of the performance of ActoDatA, a novel actor-based software library for distributed data analysis and machine learning in Java that we have recently developed. To do so we have implemented an evolutionary machine learning application based on a distributed island model. The model implementation is compared to an equivalent implementation in ECJ, a popular general-purpose evolutionary computation library that provides support for distributed computing. The testbed used for comparing the two distributed versions has been an application of Sub-machine code Genetic Programming to the design of efficient low-resolution binary image classifiers. The results we have obtained show that the ActoDatA implementation is more efficient than the corresponding ECJ implementation.\",\n \"Title: Continual representation learning for node classification in power-law graphs\\nYear: 2022\\n\\nAbstract: The recent advent of node embedding techniques enabled a more efficient application of machine learning techniques on graphs. These techniques allow each node of a network to be encoded into an arbitrary low-dimensional vector representation, which can be exploited by statistical learning models. However, the main limitation of these approaches is that the embedding task is solved as an optimization problem on a static snapshot of the graph. In a real scenario, temporal dynamics should be considered with some consequences: new nodes might join the network and get a representation of only these new ones. As a consequence, a new training step over the entire graph is required. Even more, training models with static approaches can have resource-intensive requirements, especially when dealing with large networks. In light of this, a continual feature learning that builds on top of previously already learned knowledge (previous partial embedding of the network) and well-known properties can be a solution to address both limitations efficiently in real scenarios. Our approach is suitable for graphs whose degree distribution is described by a power-law function that is a common property of real systems. This research work presents three main scientific contributions: (a) a continual feature learning meta-algorithm for node embedding, which exploits properties of power-law distribution and spaces alignment techniques; It is suitable with any traditional node embedding techniques that relies on embedding spaces (b) we demonstrate empirically, by performing node labeling tasks, that a lightweight solution to encode new nodes, based on limited knowledge of the embedding of the network hub-nodes, can provide comparable or better performances, with respect to static approaches. (c) Finally, we experimented our algorithm in the temporal graphs domain and we achieved better results in node classification compared with other state of the art techniques.\",\n \"Title: Mobility in Unsupervised Word Embeddings for Knowledge Extraction-The Scholars' Trajectories across Research Topics\\nYear: 2022\\n\\nAbstract: In the knowledge discovery field of the Big Data domain the analysis of geographic positioning and mobility information plays a key role. At the same time, in the Natural Language Processing (NLP) domain pre-trained models such as BERT and word embedding algorithms such as Word2Vec enabled a rich encoding of words that allows mapping textual data into points of an arbitrary multi-dimensional space, in which the notion of proximity reflects an association among terms or topics. The main contribution of this paper is to show how analytical tools, traditionally adopted to deal with geographic data to measure the mobility of an agent in a time interval, can also be effectively applied to extract knowledge in a semantic realm, such as a semantic space of words and topics, looking for latent trajectories that can benefit the properties of neural network latent representations. As a case study, the Scopus database was queried about works of highly cited researchers in recent years. On this basis, we performed a dynamic analysis, for measuring the Radius of Gyration as an index of the mobility of researchers across scientific topics. The semantic space is built from the automatic analysis of the paper abstracts of each author. In particular, we evaluated two different methodologies to build the semantic space and we found that Word2Vec embeddings perform better than the BERT ones for this task. Finally, The scholars' trajectories show some latent properties of this model, which also represent new scientific contributions of this work. These properties include (i) the correlation between the scientific mobility and the achievement of scientific results, measured through the H-index; (ii) differences in the behavior of researchers working in different countries and subjects; and (iii) some interesting similarities between mobility patterns in this semantic realm and those typically observed in the case of human mobility.\",\n \"Title: Fine-Grained Agent-Based Modeling to Predict Covid-19 Spreading and Effect of Policies in Large-Scale Scenarios\\nYear: 2022\\n\\nAbstract: Modeling and forecasting the spread of COVID-19 remains an open problem for several reasons. One of these concerns the difficulty to model a complex system at a high resolution (fine-grained) level at which the spread can be simulated by taking into account individual features. Agent-based modeling usually needs to find an optimal trade-off between the resolution of the simulation and the populati...\",\n \"Title: High-Performance Computing and ABMS for High-Resolution COVID-19 Spreading Simulation\\nYear: 2022\\n\\nAbstract: This paper presents an approach for the modeling and the simulation of the spreading of COVID-19 based on agent-based modeling and simulation (ABMS). Our goal is not only to support large-scale simulations but also to increase the simulation resolution. Moreover, we do not assume an underlying network of contacts, and the person-to-person contacts responsible for the spreading are modeled as a function of the geographical distance among the individuals. In particular, we defined a commuting mechanism combining radiation-based and gravity-based models and we exploited the commuting properties at different resolution levels (municipalities and provinces). Finally, we exploited the high-performance computing (HPC) facilities to simulate millions of concurrent agents, each mapping the individual's behavior. To do such simulations, we developed a spreading simulator and validated it through the simulation of the spreading in two of the most populated Italian regions: Lombardy and Emilia-Romagna. Our main achievement consists of the effective modeling of 10 million of concurrent agents, each one mapping an individual behavior with a high-resolution in terms of social contacts, mobility and contribution to the virus spreading. Moreover, we analyzed the forecasting ability of our framework to predict the number of infections being initialized with only a few days of real data. We validated our model with the statistical data coming from the serological analysis conducted in Lombardy, and our model makes a smaller error than other state of the art models with a final root mean squared error equal to 56,009 simulating the entire first pandemic wave in spring 2020. On the other hand, for the Emilia-Romagna region, we simulated the second pandemic wave during autumn 2020, and we reached a final RMSE equal to 10,730.11.\",\n \"Title: Machine Learning for Bankruptcy Prediction in the American Stock Market: Dataset and Benchmarks\\nYear: 2022\\n\\nAbstract: Predicting corporate bankruptcy is one of the fundamental tasks in credit risk assessment. In particular, since the 2007/2008 financial crisis, it has become a priority for most financial institutions, practitioners, and academics. The recent advancements in machine learning (ML) enabled the development of several models for bankruptcy prediction. The most challenging aspect of this task is dealing with the class imbalance due to the rarity of bankruptcy events in the real economy. Furthermore, a fair comparison in the literature is difficult to make because bankruptcy datasets are not publicly available and because studies often restrict their datasets to specific economic sectors and markets and/or time periods. In this work, we investigated the design and the application of different ML models to two different tasks related to default events: (a) estimating survival probabilities over time; (b) default prediction using time-series accounting data with different lengths. The entire dataset used for the experiments has been made available to the scientific community for further research and benchmarking purposes. The dataset pertains to 8262 different public companies listed on the American stock market between 1999 and 2018. Finally, in light of the results obtained, we critically discuss the most interesting metrics as proposed benchmarks for future studies.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":84,"string":"84"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":45,"string":"45"}}},{"rowIdx":46,"cells":{"question_id":{"kind":"string","value":"Volker Jungnickel"},"question":{"kind":"string","value":"Generate an abstract for the title \"Efficient MAC protocol for JT CoMP in small cells\" using the following items: 1. MAC protocol\n2. Interference coordination\n3. Joint transmission-coordinated multi-point\n4. Channel state information requests\n5. LTE-Advanced testbed"},"answer":{"kind":"string","value":"In this paper, we investigate an efficient MAC protocol for interference coordination in small cells embedded in a macro-cell mobile network. We perform joint transmission (JT)-coordinated multi-point (CoMP), where cells in the cluster include adjacent macro-cells as suggested by the small-cell terminal. Most gains compared to uncoordinated transmission come from selecting the right users in these macro-cells. For minimizing the feedback overhead, we propose successive channel state information (CSI) requests. Thereby we replace users in the set until all of them experience consistently enhanced performance when using JT-CoMP. Gains can be further increased by MIMO mode switching in each cell and frequency-selective scheduling. We tested our algorithms over coherently measured multi-cell channels in the LTE-Advanced testbed in Berlin where small cells were embedded at several places. Using these algorithms, performance becomes comparable to a popular bound assuming no more intra-cluster interference while feedback overhead and complexity are substantially reduced."},"correct_answer":{"kind":"string","value":"In this paper, we investigate an efficient MAC protocol for interference coordination in small cells embedded in a macro-cell mobile network. We perform joint transmission (JT)-coordinated multi-point (CoMP), where cells in the cluster include adjacent macro-cells as suggested by the small-cell terminal. Most gains compared to uncoordinated transmission come from selecting the right users in these macro-cells. For minimizing the feedback overhead, we propose successive channel state information (CSI) requests. Thereby we replace users in the set until all of them experience consistently enhanced performance when using JT-CoMP. Gains can be further increased by MIMO mode switching in each cell and frequency-selective scheduling. We tested our algorithms over coherently measured multi-cell channels in the LTE-Advanced testbed in Berlin where small cells were embedded at several places. Using these algorithms, performance becomes comparable to a popular bound assuming no more intra-cluster interference while feedback overhead and complexity are substantially reduced."},"documents":{"kind":"list like","value":["Title: Scaleable network multicast for cooperative base stations\nYear: 2008\n\nAbstract: Cooperative joint transmission and detection algorithms have a high potential to increase the capacity of cellular radio systems. This paper investigates efficient network layer protocols to realize such cooperation over a heterogeneous, bandwidth-limited backhaul. Target systems are MIMO-OFDM cellular communication systems with flat hierarchy (no central unit), and we take 3GPP LTE as example. The proposed architecture uses IP multicast for stations receiving the same information and is scaleable by dynamically cooperating only on frequency subbands. SINR and mobility thresholds are used to first cooperate for critical cell-edge users with low mobility, where most interference reduction gain is to be expected.","Title: Adaptive Feedback Compression for Joint Transmission Coordinated Multi-Point.\nYear: 2013\n\nAbstract: In this paper, we study adaptive feedback compression of explicit multi-cell channel state information (CSI) for joint transmission coordinated multi-point (JT CoMP) in future mobile networks. The scheme comprises of three steps: First, the strongest cells are clustered using a network-defined threshold. Next, the strongest taps are selected using a threshold related to noise and out-of-cluster interference. Finally, adaptive quantization is applied so that the channel mean square error (MSE) remains sufficiently small. We show that the number of quantization bits grows linearly with the signal to noise ratio (SNR) in dB, as required by information theory. Results indicate that explicit CSI from all relevant cells around a terminal can be provided using few kbits per reporting interval in 20 MHz bandwidth. The scheme is implemented and tested in real time.","Title: Real-time signal processing for multiantenna systems: algorithms, optimization, and implementation on an experimental test-bed\nYear: 2006\n\nAbstract: A recently realized concept of a reconfigurable hardware test-bed suitable for real-time mobile communication with multiple antennas is presented in this paper. We discuss the reasons and prerequisites for real-time capable MIMO transmission systems which may allow channel adaptive transmission to increase link stability and data throughput. We describe a concept of an efficient implementation of MIMO signal processing using FPGAs and DSPs. We focus on some basic linear and nonlinear MIMO detection and precoding algorithms and their optimization for a DSP target, and a few principal steps for computational performance enhancement are outlined. An experimental verification of several real-time MIMO transmission schemes at high data rates in a typical office scenario is presented and results on the achieved BER and throughput performance are given. The different transmission schemes used either channel state information at both sides of the link or at one side only (transmitter or receiver). Spectral efficiencies of more than 20 bits/s/Hz and a throughput of more than 150 Mbps were shown with a single-carrier transmission. The experimental results clearly show the feasibility of real-time high data rate MIMO techniques with state-of-the-art hardware and that more sophisticated baseband signal processing will be an essential part of future communication systems. A discussion on implementation challenges towards future wireless communication systems supporting higher data rates (1 Gbps and beyond) or high mobility concludes the paper.","Title: On the Value of Synchronous Downlink MIMO-OFDMA Systems with Linear Equalizers\nYear: 2008\n\nAbstract: Cellular radio systems are often limited due to the presence of cochannel interference. Basi- cally, radio systems may be operated by utilizing asyn- chronous or synchronous downlink transmission from all base stations in the system, where synchronization between terminals and their serving base station is mandatory in both concepts. We provide a comparison between the theoretical achievable spectral efficiency in an orthogonal frequency division multiple access sys- tems using different linear equalizers and their resulting performance taking estimation errors into account. It is shown, that the choice of the appropriate receiver depends on the degree of synchronization in the system. We demonstrate that a 3G Long Term Evolution radio system may achieve higher spectral efficiency thanks to interference suppression if fully synchronized data transmission from all base stations is introduced. I. Introduction Multi-cell interference is undoubtedly the major limiting factor in full-coverage broadband wireless access networks. Mitigating its effect onto the downlink data transmission is a key challenge in future wireless communication systems. The better the knowledge about the interference channels, the better is also the basis for any interference mitigation. Existing and future wireless standards, as 802.11n, WiMAX, 3G HSDPA and its long-term evolution (3G- LTE) have built-in means for multiple-input multiple- output (MIMO) signaling. Multi-antenna terminals enable interference suppression at the receiver side and thus the radio system may profit from a higher spectral efficiency. Simple receiver-based schemes like optimal interference rejection combining (1) are known to significantly increase the system's spectral efficiency (2). However, its appli- cability in MIMO-OFDMA systems is not fully evident yet, since it is highly sensitive to channel estimation errors. This work shows the spectral efficiency gains in an OFDMA system using the interference rejection combining (IRC) instead of the maximum ratio combining (MRC) receiver, while considering channel estimation errors. We always assume synchronization between mobile terminals (MTs) and their serving base station (BS) (3). The system parameters are chosen from the current draft specification of the 3G Long Term Evolution (3G-LTE) (4).","Title: Localized SC-FDMA with constant envelope.\nYear: 2013\n\nAbstract: Singe-carrier frequency-division multiple access (SC-FDMA) enables simplified equalization and flexible multiuser scheduling in the frequency domain. Compared to orthogonal frequency division multiple access (OFDMA), it has reduced envelope fluctuations in the same bandwidth. SC-FDMA is widely used in mobile communications, where the focus is on spectral efficiency. Here, we consider an evolution towards better energy efficiency. We propose evolved transmission schemes combining energy-efficient modulation and frequency-domain filtering. Using Gaussian minimum-shift keying (GMSK) and filtered pi/2 binary phase-shift keying (BPSK), the peak-to-average power ratio (PAPR) can be reduced down to 0 and 1.9 dB, respectively, while penalties at the receiver side are negligible.","Title: Multiple CFOs in OFDM-SDMA uplink: interference analysis and compensation\nYear: 2009\n\nAbstract: In OFDM-based space division multiple access (SDMA) systems, multiple users are served by a multiantenna base station simultaneously on the same frequency resources. In the uplink, each user's signal may be distorted by an independent carrier frequency offset (CFO), which impairs the orthogonality of the subcarrier signals and, if not properly compensated, results in performance degradations. We analyze the influence of multiusers' CFOs on the signal transmission in the OFDM-SDMA uplink and derive suitable bounds for the achievable signal-to-interference conditions. By modifying the signal model suitably, we develop a simple scheme for partial compensation of the CFO distortions. It allows to maintain the subcarrier-wise channel equalization and thus is well suited to be applied for a real-time system implementation. However, as CFOs impair the cyclic structure of the OFDM symbols, our scheme is not able to compensate for the entire distortion. The remaining interference is treated as additional noise, which limits the supported size of the CFOs.","Title: A channel model for wireless infrared communication.\nYear: 2000\n\nAbstract: An simple analytic model for the light propagation in indoor environments is presented. Ray tracing simulations confirm that the model is applicable to the wireless infrared communication channel in rooms.","Title: 12x12 MIMO-OFDM Realtime Implementation for 3GPP LTE+ on a Cell Processor.\nYear: 2008\n\nAbstract: We present a realtime implementation of the time-critical core functions for 12 x 12 MIMO-OFDM (12 data streams) with LTE parameters on a Cell Broadband Engine Processor. An MMSE equalizer matrix update interval of 1 ms (high mobility) is achieved with less than 50% CPU utilization. Concurrent bidirectional processing (precoding and postprocessing) is shown to be feasible with this update rate.","Title: Interference-Aware Scheduling in the Synchronous Cellular Multi-Antenna Downlink\nYear: 2009\n\nAbstract: Abstract—We consider the downlink of a multi-user MIMO OFDM system in a cellular environment, where users are scheduled to the transmission resources in frequency and space. Targeting a practical solution, we assume the use of fixed DFT- based pre-coding beams at the base stations and linear receivers at the multi-antenna terminals. After having received feedback on the frequency-selective interference conditions from all terminals, each base station schedules the terminals to their resources of highest quality while following a fair scheduling policy. It is shown that this rather simple practical concept enables spatial multiplexing transmission for all users in the system, in particular even for users at cell edge. This results in a capacity scaling that is similar to the one known for isolated point-to-point links. Finally, the system is shown to achieve a performance close to the ideal case if proper techniques to estimate the desired and interfering channels are applied.","Title: Distributed Uplink Base Station Cooperation for Optimal SIR Assignment\nYear: 2010\n\nAbstract: Base station cooperation is considered as a promising approach to increase the quality of service (QoS) in uplink. Base stations are connected via high-capacity backhaul links, which makes it possible to perform joint detection through information sharing among several base stations. Joint detection broadens the feasible signal to interference ratio (SIR) region, in which any SIR assignment for all users can be concurrently supported. Thus it provides a higher system throughput. We characterized the Pareto-optimal boundary of the feasible SIR region of power control with base station cooperation by utilizing the property of concave interference function. We suggest a distributed power control algorithm that exploits the broader feasible SIR region and optimizes the SIR assignment. Depending on the feasibility of the network to support cooperation, we analyze 3 degrees of cooperation: no cooperation, limited cooperation, and full cooperation.","Title: REAL-TIME EXPERIMENTS ON CHANNEL ADAPTIVE TRANSMISSION IN THE MULTI-USER UP-LINK AT VERY HIGH DATA RATES USING MIMO-OFDM\nYear: 2006\n\nAbstract: In this paper we focus on channel adaptive transmission in the multi-user OFDM Uplink where the base station uses multiple an- tennas. The additional degree of freedom in space requires extra signal processing effort which becomes challenging especially for a high data rate implementation in real-time. Our MIMO-OFDM experimental system which is capable to transmit data rates beyond 1 Gbit/s, was enhanced by adaptive re- source allocation, where the modulation on each antenna and each sub-carrier was controlled by a narrow-band feed-back channel. We present experimental results for the total rate achieved at the base station and the individual rates per user terminal in line- of-sight and non-line-of-sight scenarios. We compare the rates ex- pected from theory on the measured indoor channels with rates achieved in the experiments.","Title: Polarization characteristics of multiple-input multiple-output channels\nYear: 2008\n\nAbstract: In this paper, we investigate the polarization characteristics of the multiple-input multiple-output (MIMO) channels. The cross polarization discrimination (XPD) is found to change over time, while its variation in frequency domain is relatively small. The probability density function (PDF) of the XPD follows a Gaussian distribution. Analysis and measurement results show that the polarization preserves better in the line of sight (LOS) scenario. In the case of non line of sight (NLOS) scenario, the polarization of the signals is destroyed due to multiple reflections, diffractions or scattering. The difference between the XPDs of the vertically polarized and horizontally transmission highly depends on the specific propagation environment between the transmitter and the receiver. Comparison of the capacity in different scenarios further shows that the polarization diversity gain is less in NLOS scenarios compared with that in LOS scenarios.","Title: Distributed Base Station Cooperation via Block-Diagonalization and Dual-Decomposition\nYear: 2008\n\nAbstract: It has been recently shown that base station cooperation may yield great capacity improvement in downlink multiple antenna cellular networks. However, the proposed solutions assume that there is a central processing unit which coordinates the information exchange and determines the optimal resource allocation of the overall cellular network. Whilst the benefits of base station cooperation are large, computational burden of the central unit can be significant. Thus distributed solutions are desirable. This paper suggests a distributed solution for base station cooperation via block-diagonalization and dual-decomposition to maximize the weighted sum network capacity under per-antenna power constraint. The block-diagonalization pre-coding matrix is determined separately at each base station. It enables the full potential of base station cooperation by determining a trade-off between inter-cell interference mitigation, spatial multiplexing and macro diversity. The power allocation problem is formulated as a network utility maximization ( NUM) problem. By looking at its Lagrangian dual problem, the decomposable structure of the optimization problem is revealed. This leads to a distributed and iterative algorithm that converges to the global optimum. The advantage of macro diversity in addition to inter-cell interference mitigation and spatial multiplexing in base station cooperation context is studied and shows superior performance in terms of a higher capacity increase with lower variance. (1)","Title: Interference Management For Future Cellular Ofdma Systems Using Coordinated Multi-Point Transmission\nYear: 2010\n\nAbstract: Todays cellular systems reach their limits for data rate due to the continuously increasing amount of subscribers using wireless service for business purposes or in leisure time (smartphone effect) Thus re cent research focuses on concepts for interference management for cellular OFDMA systems This paper addresses various techniques related to this topic while considering the concepts with lowest complexity and backhaul costs as promising candidates to be applied first Starting from interference canceling receivers over multi user MIMO using fixed precoding to multi cell interference estimation which improves the precision of link adaptation we discuss closed loop cooperative transmit beamforming using multiple base stations grouped into a wireless distributed network (WDN) which is denoted as coordinated multi point Joint transmission in the 3GPP LTE Advanced standardization It is obvious the more sophisticated these techniques are the higher the demands for feedback and backhaul become Performance results are provided by employing multi cell simulations according to recommendations from 3GPP In addition feasibility of coordinated multi point joint transmission is demonstrated in a real time proto type setup ie in the Berlin LTE Advance Testbed","Title: Acoustic Channel Model For Adaptive Downhole Communication Over Deep Drill Strings\nYear: 2013\n\nAbstract: For reducing costs in drilling technology, seismic prediction while drilling (SPWD) is envisioned. SPWD needs a fast data link bringing up the seismic data from bottomhole to the ground. In this paper, we propose a flexible and easy-to-use acoustic channel model for long drill strings. The model enables efficient design of adaptive OFDM communication links and prediction of achievable data rates for variable string dimensions. We describe acoustic wave propagation by the S-parameters of the drill string modelled as a series of alternating short and long resonators due to segments of constant acoustic impedance. All segments have been parametrised and the final channel is a concatenation of all its segments. We verify the new model by comparison with measurements on a 55 m long drill string. By using our model, the properties of a manifold of real drill pipes with variable dimensions can be predicted. We investigate the impact of length variations typical for rough drilling applications. For efficient communications over 1.5 km, length variations of the screwed tool joints should be limited to a few centimetres while the pipe length may vary up to one meter.","Title: A closed concept for synchronization and cell search in 3GPP LTE systems\nYear: 2009\n\nAbstract: In this paper we investigate the time and frequency synchronization as well as the sector and cell search for the 3GPP Long Term Evolution (LTE) downlink. The proposed algorithms rely on the synchronization and cell-specific reference signals and are hence compliant to most recent 3GPP specifications. Time and (fractional) frequency offset coarse synchronization are performed in the time domain with the cyclic prefix based autocorrelation, while the sector and cell as well as the integer frequency offset are estimated in the frequency domain by using the primary and secondary synchronization signals. To improve the cell detection reliability, the estimated cell is afterwards confirmed through the cell-specific reference signal. All algorithms are evaluated under multipath channel conditions and an initial carrier frequency mismatch. Compromising high performance with reasonable implementation complexity, we draw a practical solution for an LTE receiver.","Title: On Hardware Implementation Of Multiuser Multiplexing For Sc-Fdma\nYear: 2007\n\nAbstract: A simple algorithmic scheme is proposed which calculates multiple variable-length FFTs/IFFTs at once by a single fixed-length one. The algorithm exploits the fact that the transform of a periodic signal is a line spectrum, the linearity property of FFT/IFFT and the shift theorem. The overall algorithm complexity is higher than calculating separate variable-length transforms, but the ease of implementation makes the scheme well-suited for FPGA based rapid prototyping systems. Because in SC-FDMA systems multiple variable-length transforms are needed for different users, the algorithm can be used to implement multiuser multiplexing. The scheme can be applied to DFT/IDFT as well as FFT/IFFT implementations.","Title: Polarization rotation evaluation for macrocell MIMO channel\nYear: 2009\n\nAbstract: In this paper, the impact of the polarization on the performance of the multiple-input multiple-output (MIMO) channel with cross-polarized antennas has been investigated based on the outdoor macrocell measurement at 2.53 GHz. A simple model which can capture the major characteristics of the cross polarized channel is proposed. The effective polarization rotation during the propagation is evaluated using the proposed model, and found to follow a bimodal Rayleigh distribution. The commonly accepted uniform distribution polarization rotation angle is a reasonable but coarse assumption compared with our estimated results. The vertical and horizontal polarization perform similarly in line-of-sight (LOS) scenario, but may be different in non-LOS (NLOS) scenario depending on the environment where the receiver is located. The polarization diversity outperforms the spatial diversity in LOS scenario, but shows relatively small gain in a rich scattering scenario. This is further proofed by the comparison of the capacity of a 4 × 4 MIMO channel with cross-polarized antennas.","Title: Implementation Of Channel Aware Scheduling And Bit-Loading For The Multiuser Simo Mac In A Real-Time Mimo Demonstration Test-Bed At High Data Rate\nYear: 2004\n\nAbstract: In this paper we discuss a cross layer approach to apply channel aware scheduling for a multi user SIMO multiple access channel. We show how optimum power and rate allocation can be achieved when successive interference cancellation (SIC) and a MMSE receiver is used at the base station. Combining this capacity optimum results with quality of service requirements of the users (e.g. data rate or delay) we analyze the Joint optimization problem and propose a suboptimum hut applicable scheduling approach which can he implemented already. today on real time capable hardware. Different scheduling policies were implemented in the real time MIMO test-bed in our lab. We describe the particular hardware setup for the experiments and present measurement results on various scheduling policies under power and bit error rate constraints with an average up-link spectral efficiency of tip to 17 bits/s/Hz with 3 base station antennas.","Title: Practical Channel Interpolation For Ofdma\nYear: 2006\n\nAbstract: This paper addresses piecewise frequency domain interpolation for OFDMA channels when raw estimates are given on a sparse grid of pilot carriers in a fraction of the spectrum only. Starting from the optimal linear interpolation which needs a-priori information on the power delay profile and the SNR, we develop robust suboptimal schemes that do not require such information. One scheme is based on singular value decomposition and it allows the estimation of the SNR. In practice, however, it is difficult to obtain the required information on the power delay profile. To ensure robustness of the filter to mismatched channel parameters, a favorable assumption of the power delay profile is suggested for the filter design. It is further shown that a full-spectrum interpolation assembled from multiple piecewise interpolation results has a dramatically reduced complexity which makes it suitable for real-time implementation.","Title: Interference-aware scheduling in the multiuser MIMO-OFDM downlink\nYear: 2009\n\nAbstract: With the introduction of orthogonal frequency-division multiplexing and multiple antennas in cellular networks, there are new opportunities to adapt the transmission to propagation and interference conditions. In this article we describe a practical approach using space-frequency-selective multiuser MIMO scheduling. Frequency-selective feedback is provided on achievable data rates for preferred single- and multistream transmission modes. The base station selects the best mode while providing instantaneous fairness. We observe that multiuser transmission increases the probability of using multistream transmission. Besides the benefits from optimal combining at the physical layer, there is an additional gain at the MAC layer since the estimation of achievable rates becomes more precise. Altogether, 93 percent of the theoretical throughput can be realized by synchronizing the base stations and providing cell-specific reference signals. We have implemented essential functions of the approach in real time on an experimental 3GPP LTE prototype in 20 MHz bandwidth. Feasibility of the key features is proven in laboratory and field trials.","Title: Modeling and Measurement of MIMO Relay Channels\nYear: 2008\n\nAbstract: This paper proposes a relay channel model which takes into account the influence of relay location and antenna configuration. Simulation results show that when relay is in the line-of-sight (LOS) propagation environment, the channel capacity will degrade. To improve the performance of the channel, water-filling (WF) algorithm is used to allocate the power, simulation results shows that the WF-based relay channel outperforms the uniform power allocation channel. The radiation pattern of the relay antenna is also an importance factor which affects the channel capacity in this case. The widely used Rayleigh channel model overestimates the performance of the channel compared with our model when the location of the relay is not in the scenario where Ricean K-factor is zero. Measurements have been done at 2.53 GHz to investigate the above-rooftop and ground-level relay channels. Results indicate that above-rooftop deployment is very efficient to improve the capacity and coverage.","Title: On the Capacity of Intensity-Modulated Direct-Detection Systems and the Information Rate of ACO-OFDM for Indoor Optical Wireless Applications.\nYear: 2012\n\nAbstract: In this paper we derive information theoretic results for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) in an intensity modulated direct detection (IM/DD) optical communication system subject to a range of constraints. ACO-OFDM is a form of OFDM designed for IM/DD systems. It is an effective solution to intersymbol interference (ISI) caused by a dispersive ch...","Title: Implementation of adaptive channel inversion in a real-time MIMO system\nYear: 2004\n\nAbstract: The implementation of adaptive channel inversion into a real-time single carrier MIMO test-bed is reported for the first time. Since no joint detection is possible at the distributed users, all signal preprocessing is performed at the transmitter which adapts the transmission links to all the mobile terminals depending on the actual channel situation. This means that the number of reliably supportable users is controlled as well as the modulation, ensuring BER targets for all users. The implemented algorithms are described and measurement results have shown the stable sum rate throughput of several 10 Mbit/s for a MIMO base station with 4 transmit antennas which supports up to 4 mobile terminals simultaneously. Since the transmission is based on optimum feedback of the channel knowledge to the transmitter, the results given here can be understood as a kind of an upper practical performance bound for the application of linear channel pre-distortion.","Title: Flexible demonstrator platform for cooperative joint transmission and detection in next generation wireless MIMO-OFDM networks\nYear: 2008\n\nAbstract: This paper presents a flexible demonstrator platform for cooperative joint transmission and detection in next generation wireless networks, especially cellular networks like 3GPP LTE+. The platform is shown capable of handling computational load as well as network load of jointly processing three maximum bandwidth LTE sectors with four antennas each. The platform uses a Workstation mainboard as PCI Express backplane. Joint signal processing is done on a Cell processor, protocol handling on an IXP2350 network processor. For baseband sample exchange a 10GBit/s optical network interface card is used. First results show the Cell processor capable of computing the 12x12 modified LTE MIMO-OFDM processing concurrently for precoding (downlink) and postprocessing (uplink) with a MIMO matrix update interval of 1ms (high mobility).","Title: Capacity Measurements in a Cooperative MIMO Network\nYear: 2009\n\nAbstract: Cooperation between adjacent base stations (BSs) may reduce intercell interference in future cellular networks and enhance network capacity in this way. The potential of cooperation is evaluated in this paper based on measurements conducted at 5.2 GHz in a campus environment with four overlapping cells. For each individual link of the four BS and five terminal locations, a 10 times 16 antenna conf...","Title: Capacity Measurements In A Multicell Mimo System\nYear: 2006\n\nAbstract: In future wireless networks, cooperation between the base stations may reduce the effects of intercell interference and enhance the capacity per cell. In this paper, the potential of such cooperation is evaluated using measurements of the information-theoretic channel capacity at 5.2 GHz in 4 overlapping urban macrocells with 5 users. In each link, a 10-transmit 16-receive antenna configuration is used.Results for individual links between terminals and base stations, valid for 60% of the scenarios, indicate that the direct signal has a significant impact on the channel structure. The direct signal contributes two spatial degrees of freedom due to the polarization. Rich scattering is observed when the direct signal is blocked.Results for the multiuser multicell scenario demonstrate for the first time experimentally that the intercell interference leads to an enhanced rank of the joint multiuser multicell channel matrix. Compared to a conventional cellular system, where a fixed assignment of different radio resources is used in adjacent cells in order to avoid the interference, it is better to exploit the interference by cooperation. This enhances the spectral efficiency by a factor of five in our measurement scenario.","Title: The role of small cells, coordinated multipoint, and massive MIMO in 5G.\nYear: 2014\n\nAbstract: 5G will have to support a multitude of new applications with a wide variety of requirements, including higher peak and user data rates, reduced latency, enhanced indoor coverage, increased number of devices, and so on. The expected traffic growth in 10 or more years from now can be satisfied by the combined use of more spectrum, higher spectral efficiency, and densification of cells. The focus of ...","Title: Design of a visible-light-communication enhanced WiFi system.\nYear: 2015\n\nAbstract: Visible light communication (VLC) has wide unlicensed bandwidth, enables communication in radio frequency (RF) sensitive environments, realizes energy-efficient data transmission, and has the potential to boost the capacity of wireless access networks through spatial reuse. On the other hand, WiFi provides more coverage than VLC and does not suffer from the likelihood of blockage due to the light of sight (LOS) requirement of VLC. In order to take the advantages of both WiFi and VLC, we propose and implement two heterogeneous systems with Internet access. One is the hybrid WiFi-VLC system, utilizing unidirectional VLC channel as downlink and reserving the WiFi back-channel as uplink. The asymmetric solution resolves the optical uplink challenges and benefits from the full-duplex communication based on VLC. To further enhance the robustness and increase throughput, the other system is presented, in which we aggregate WiFi and VLC in parallel by leveraging the bonding technique in Linux operating system. Online experiment results reveal that the hybrid system outperforms the conventional WiFi for the crowded environments in terms of throughput and web page loading time; and also demonstrate the further improved performance of the aggregated system when considering the blocking duration and the distance between access point and user device.","Title: Adaptive Modulation and Turbo Coding for 3GPP LTE Systems with Limited Feedback\nYear: 2014\n\nAbstract: Link adaptation is recognized as a powerful tech- nique for enhancing spectral efficiency over wireless channels. While its theoretical aspects are well understood, it is not clear yet how to practically deal with limited feedback. In this paper, we study a frequency-selective link adaptation scheme for orthogonal frequency division multiplexing (OFDM). The modulation order is adjusted per resource block (smallest time-frequency unit assigned to a user), while a joint coding rate is used for all variable-length codewords, comprising resource blocks with different modulations. In order to meet the required coding rate, adaptive puncturing is applied after a fixed-rate Turbo encoder. Link adaptation is guided by an effective signal-to-noise ratio (SNR), which is calculated over several subcarriers by a mapping function. 3GPP LTE compliant link-layer simulations were performed for optimizing the SNR interface so that the spectral efficiency is maximized under a codeword error rate constraint and tradeoffs between feedback savings and spectral efficiency losses were elaborated. The result is a thoroughly tested link-layer abstraction for 3GPP LTE including adaptive modulation and bit-interleaved coding that can be also used for system-level simulations towards future mobile radio systems.","Title: Zero forcing equalizing filter for MIMO channels with intersymbol interference\nYear: 2002\n\nAbstract: Equalization in the time domain is a well- known technique for combating intersymbol interference (ISI) in frequency selective channels. In this paper we derive the general structure of the linear zero forcing (ZF) equaliz- ing filters for multiple input multiple output (MIMO) com- munication systems with more outputs than inputs. These filters are finite impulse response (FIR) filters in general and their structure is determined by the number of inputs and outputs. The relation between the spatial diversity of the system and the necessary filter length is worked out and it is shown, that an optimal time lag in the filter will improve the performance considerably.","Title: On linear pre-processing in multi-antenna systems\nYear: 2002\n\nAbstract: We study linear pre-processing for multi-antenna systems when the channel is perfectly known at the transmitter. In particular, the capacity of linear and adaptive channel inversion is compared to the optimum water-filling. When equal numbers of antennas are used at the transmitter and at the receiver, the outage probability with linear inversion is rather large. Outage is remarkably reduced when more antennas are used at the transmitter. Adaptive inversion approximates the water-filling capacity at small transmitter power and so it is robust against fading correlation. The average transmitter power with linear inversion depends on the numbers of antennas at the transmitter and at the receiver. For Rayleigh fading, we compare the bit error performance to V-BLAST.","Title: Limits of the achievable symbol rate in flat fading MIMO systems\nYear: 2003\n\nAbstract: The irreducible error, introduced by the time dispersion of the radio channel for multiple-input multiple-output (MIMO) systems with flat fading detection algorithms are investigated analytically and by link level simulations. Using an adequate synchronisation method, the error floor is determined only by the intersymbol interference, for which a formula is derived. The maximal data rate is not only determined by the value of this interference, but also by the modulation scheme, antenna configuration and channel condition.","Title: Performance of MIMO Rake receivers in WCDMA systems\nYear: 2004\n\nAbstract: The rake receiver is investigated for spatial multiplexing (SM) in wide-band code-division multiple access systems. In general, the SM increases the data rate and the diversity order as well. The appropriate maximum likelihood detector is derived in this paper and it is shown that the diversity order is related to the product of the numbers of receive antennas and taps. With realistic numbers similar diversity orders may be achieved also with reduced complexity detection schemes. Finally, a standard-conformal scrambling technique is proposed to enhance the performance and to equalize it among the full set of orthogonal variable spreading factor (OVSF) sequences used in the third generation cellular system.","Title: Statistics of the Ricean K-Factor at 5.2 Ghz in an Urban Macro-Cell Scenario\nYear: 2006\n\nAbstract: In this paper we analyze 5.2 GHz channel measurement data in an urban macro-cell scenario in order to figure out the likelihood of a free line-of-sight and the statistics of the Ricean K-factor. We introduce a physical method to obtain this information from the Doppler delay spectrum taking GPS information into account. It is found, that for short distances the direct signal is available in 62% of all cases. However, the likelihood reduces at larger distances. In addition the average K-factor reduces with increasing distance. Measured distributions are fitted and parameters are provided for use in channel modelling","Title: Effects of multiple users' CFOs in OFDM-SDMA up-link - an interference model\nYear: 2006\n\nAbstract: OFDM-SDMA systems are intended to allow multiple users to communicate simultaneously with a base station in the same frequency band. In these systems, each user signal may be distorted by an independent carrier frequency offset (CFO), which will result in a severe degradation of the system performance if no CFO compensation is carried out. The standard compensation algorithms known from single-user SISO systems do not apply in this context, hence novel compensation techniques have to be introduced. We analyse the influence of multi-users' CFOs on the OFDM-SDMA signal transmission and develop a scheme for their compensation with low complexity. Due to a disturbance of the inherent structure of the OFDM system, the scheme is not capable to compensate for all the effects generated by the CFOs. The remaining interferences may be treated as additional noise, thus setting tight limits for the size of the CFOs which are supported by the system.","Title: Joint Transmission and Detection in Hexagonal Grid for 3GPP LTE\nYear: 2008\n\nAbstract: Cooperative joint transmission and detection algorithms have a high potential to increase the capacity of cellular radio systems. This paper proposes a mapping of areas of joint signal processing into the cellular hexagonal grid architecture, balancing network load, computational load and physical layer overhead versus interference reduction gain. The proposed communication architecture is shown to be realizable with off- the-shelf hardware.","Title: Performance evaluation of a 3GPP LTE terminal receiver\nYear: 2008\n\nAbstract: In this paper we present the evaluation of a receiver signal processing chain for a 3GPP long term evolution (LTE) terminal, including coarse synchronisation, channel estimation, fine syncronisation (tracking), MIMO equalization and detection. Algorithm blocks are first individually explained and simulatively evaluated with a realistic channel model. Adjustments of the blocks to each other for improved robustness are described, like interaction between time synchronization and channel estimation performance. After joint optimization, the performance of the complete chain is evaluated. Practical tradeoffs between complexity and performance are investigated and low-complexity algorithms are used. The presented receiver achieves an implementation loss of about 2 dB compared to perfect synchronization and channel estimation conditions.","Title: Spatial Transmission Mode Switching in Multiuser MIMO-OFDM Systems With User Fairness\nYear: 2010\n\nAbstract: Multiantenna radio systems allow accessing the channel in diversity or spatial multiplexing (SMUX) mode. Ade- quate switching between these modes according to current channel conditions was shown to yield significant performance improve- ments while requiring little feedback from the receiving side. We present a transmission concept for the downlink of a multiuser multiple-input-multiple-output orthogonal frequency- division-multiplexing (MU-MIMO-OFDM) system aiming at high user rates with limited feedback demands. An extended score-based scheduling (SB) approach ensures fair-resource allo- cation to the users, whereas transmission mode switching is used to guarantee high user rates. The degree of fairness of the scheduler can be adapted by adequately configuring a weighting function for the scores. Comparison with single-mode schemes reveals substantial throughput gains of the adaptive switching concept. Furthermore, targeting maximum throughput, we show that a considerable proportion of the capacity of the MIMO broadcast channel (BC) can be achieved with a comparatively low amount of required feedback. Index Terms—Multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM), multiuser systems, resource allocation, score-based scheduling (SB), spatial mode switching.","Title: Channel Prediction by Doppler-Delay Analysis and Benefits for Base Station Cooperation\nYear: 2013\n\nAbstract: Base station cooperation is a promising technique for next generation cellular systems as it reduces intercell interference. In this paper, we investigate to what extent performance degradation due to the feedback delay can be compensated by advanced channel prediction. We present a new method based on a Doppler-delay model of the time-variant radio channel. In a first step, significant channel taps are extracted in the delay domain. In a second step, a high-resolution algorithm extracts the major Doppler frequency components for each channel tap. In this way, a shorter history of the channel is needed, as compared to the standard discrete Fourier transform (DFT) technique. Prediction is performed by imposing the estimated parameters into the channel model and extrapolating into future. Evaluation over the extended spatial channel model (SCME) shows that the channel mean square error can be reduced by roughly 10 dB for feedback delays between 5 and 10 ms, which translates into signal to interference ratio (SIR) gains between 5 and 15 dB, also depending on the number of jointly served terminals. Finally, it is shown that, even if the channel state information (CSI) feedback is quantized, almost the same performance can be achieved as if based on perfect channel knowledge.","Title: Analytical models for channel aging and synchronization errors for base station cooperation\nYear: 2013\n\nAbstract: Base station cooperation is a powerful technique for eliminating inter-cell interference and enhancing spectral efficiency in cellular networks. However, impairment effects due to channel time variance, channel estimation, feedback quantization and imperfect synchronization among base stations are limiting the potential gains. In this paper, we present a comprehensive signal model for multi-user multi-cellular systems with cooperating base stations, which includes those essential impairments. The effect of each impairment is captured by its mean square error (MSE), for which exact analytical expressions and accurate approximations are derived and numerically verified. Those MSE expressions can be used for link-layer abstraction, system-level evaluation and signal to interference ratio (SIR) analysis. We evaluate the spectral efficiency of cooperative networks considering a real-world scenario and find that channel aging has the largest impact on performance degradation.","Title: A UNIFIED FEEDBACK SCHEME FOR DISTRIBUTED INTERFERENCE MANAGEMENT IN CELLULAR SYSTEMS: BENEFITS AND CHALLENGES FOR REAL-TIME IMPLEMENTATION\nYear: 2009\n\nAbstract: This paper contributes to the system concept of collaborative base stations from the perspective of distributed computing. Promising signal processing approaches based on terminal feedback are re- viewed. Their specific advantages and disadvantages are discussed and a framework for feedback provision is presented. All proposed schemes have in common, that a mobile terminal can choose its desired receive strategy independently from other mobile terminals according to its computational capabilities. The effective multi-cell channel after receiver processing is fed back and distributed within the collaboration area. This allows distributed processing at each base station and makes real-time implementation feasible.","Title: Interference Limited MIMO Measurements\nYear: 2010\n\nAbstract: We evaluate the interference limited spectral efficiency of a small cellular network using measurements with 3 sites at an ISD of 750 m. Each 3-sector site is equipped with cross-polarized panel antennas. We provide an efficient method to estimate the MIMO capacity from the measured data. We then compare the capacities of SISO and 2x2 MIMO with and without interference. At a fixed SNR of 10 dB, our cross-polarized interference free 2x2 setup achieves 5.7 bps/Hz which compares well to findings from Manhattan. For the best serving BS, the median 2x2 capacity including the received power and a reuse factor of 9 is 1.7 bps/Hz. This value increases to 3 bps/Hz when using frequency reuse 3 and 4.7 bps/Hz with full reuse.","Title: Coexistence of WiFi and LiFi toward 5G: concepts, opportunities, and challenges.\nYear: 2016\n\nAbstract: Smart phones, tablets, and the rise of the Internet of Things are driving an insatiable demand for wireless capacity. This demand requires networking and Internet infrastructures to evolve to meet the needs of current and future multimedia applications. Wireless HetNets will play an important role toward the goal of using a diverse spectrum to provide high quality-of-service, especially in indoor ...","Title: MIMO-OFDM for a cellular deployment — Concepts, real-time implementation and measurements towards 3GPP-LTE\nYear: 2007\n\nAbstract: In this paper we report on the system design and a realtime implementation of a MIMO-OFDM radio transmission system close to physical layer parameters as discussed in standardization for 3GPP-Long-Term-Evolution. We describe the implementation concept and first results on over-the-air transmission with a single user set-up occupying 20 MHz bandwidth and achieving more than 150 Mbit/s gross data rate in the 2×2 MIMO down-link and more than 50 Mbit/s in the single transmit antenna up-link. The demonstration system was only recently shown to the public at various trade shows like ITU in Hongkong and 3GSM in Barcelona.","Title: Low-Latency Synchronization For Ofdm-Based Visible Light Communication\nYear: 2015\n\nAbstract: 5G wireless systems are envisioned to provide ultra-high data rates, increased robustness and low latency for new applications such as machine-to-machine (M2M) and car-to-car (C2C) communications. This paper considers high-speed visible light communication (VLC) as a candidate serving technology to fulfill this set of requirements. Synchronization as the first step towards reliable data detection is studied here thoroughly aiming at high robustness and low complexity. Three schemes are reviewed, namely Schmidl-Cox and Park autocorrelation as well as a cross-correlation based approach, all using a predefined preamble. All schemes are examined concerning their robustness against multipath propagation and their precision in time estimation versus the preamble length. It is found that the simple Schmidl-Cox scheme, originally designed for complex-valued radio waveforms, can be applied also for real-valued optical wireless waveforms. Based on these investigations, an optimized preamble structure is finally proposed. Preamble boosting and fine synchronization can also be applied to reach a similar performance like optimal cross-correlation at reduced complexity. We study the fundamental trade-off between the preamble duration and the minimum signal-to-noise ratio (SNR) required for reliable synchronization and observe that ultra-low latency needs sufficient SNR.","Title: On the impact of highpass filtering when using PAM-FDE for visible light communication\nYear: 2016\n\nAbstract: A next generation optical wireless communications standard is currently established, denoted as IEEE 802.15.7r1, targeting data rates between 1 Mbit/s and 10 Gbit/s. Selecting an appropriate transmission scheme is one of the critical tasks. Following this issue, this paper gives a review on PAM-FDE in VLC. Based on PAM-FDE laboratory measurements, we demonstrate the need to include highpass filtering into the propagation model. In this paper, numerical analyses investigate the impact of the resulting baseline wander on the performance. We include a multi-level 5S6S coding technique in order to prepare PAM-FDE for practice. Finally, research topics are summarized.","Title: A European view on the next generation optical wireless communication standard\nYear: 2015\n\nAbstract: Optical wireless technology uses light for mobile communications. The idea is to simultaneously combine the illumination provided by modern high-power light-emitting diodes (LEDs) with high-speed wireless communications. There have been numerous practical demonstrations of this concept, and the technology is now well matured to be deployed in practice. Independent market analysts forecast a high-volume market for mobile communication devices connected to the ubiquitous lighting infrastructure. This paper aims to make optical and wireless industries aware of the requirement for standardization in this area. The authors present the view of the European COST 1101 research network OPTICWISE towards a next-generation optical wireless standard aiming at data rates from 1 Mbit/s to 10 Gbit/s. Besides key technical insights, relevant use cases and main features are described that were recently adopted by the IEEE 802.15.7r1 working group. Moreover, a channel model is introduced to enable assessment of technical proposals.","Title: Software-defined Open Access for flexible and service-oriented 5G deployment\nYear: 2016\n\nAbstract: The evolution of 5G mobile radio and its complex interaction with fixed access network infrastructures poses new challenges and opportunities. In this article, a software-defined converged fixed-mobile 5G architecture is introduced using carrier-grade Ethernet as a transport platform. An active remote node (ARN) is used to connect end-users. Powered at a radio base station, the ARN aggregates the traffic of fixed and mobile radio users. Transport capacity is reduced due to statistical multiplexing, and scalability is achieved by a modular design. The ARN enables software-defined networking (SDN) via the open-networks-as-a-service (Open NaaS) control and management plane. Adopting the Open Access model, this architecture offers both, multi-technology and multi-operator features. Next generation fronthaul, resource sharing, synchronization, low latency can all be established as services to build an advanced 5G infrastructure. Key concepts of the new architecture have been realized using low-cost hardware and offer economic high-speed, fixed and mobile Internet. E.g., for wireless connectivity to macro- and small cells, mm-wave links reaching 5 Gb/s and short-range optical wireless links have been used. As data rates can be scaled up, the proposed architecture is considered future-proof for converged 5G fixed-mobile access networks.","Title: Hierarchical, virtualised and distributed intelligence 5G architecture for low-latency and secure applications.\nYear: 2016\n\nAbstract: CHARISMA aims to tackle low-latency and end-to-end security for converged fixed/wireless 5G networks in order to meet the complex demands of emerging business paradigms, such as Smart Cities, eHealth and Industry 4.0. In this paper, we present the key drivers and requirements towards a hierarchical, distributed-intelligence 5G architecture, supporting low latency, security and open access as features intrinsic to its design. We also investigate the business perspective of the proposed 5G solution and the changes that can be foreseen for the telecom ecosystem. Copyright © 2016 John Wiley & Sons, Ltd.","Title: The benefit of frequency-selective rate adaptation for optical wireless communications\nYear: 2016\n\nAbstract: In this paper, we evaluate the potential of adaptive transmission for optical wireless communications, used together with a real-valued, DC-biased optical (DCO) orthogonal frequency-division multiplexing (OFDM) waveform. Particularly, we include frequency-selective bit- and power-loading on top of DCO-OFDM. This combination is well known as discrete multitone (DMT). We work out the significant advantage of frequency-selective rate adaptation for operation in both, low signal-to-noise ratios and non-line-of-sight scenarios, as compared to using a fixed modulation format commonly applied over all subcarriers and switching between these formats. Our evaluation is based on the channel impulse responses (CIRs) provided by the IEEE task group for the 802.15.7r1 standard. Transmission bandwidth is up to 200 MHz, as supported by modern optical wireless frontends.","Title: Analog vs. next-generation digital fronthaul: How to minimize optical bandwidth utilization\nYear: 2017\n\nAbstract: In this paper we investigate two promising approaches to reduce the optical bandwidth utilization in the mobile fronthaul of next-generation cloud radio access networks. We analyze and compare the performance of an analog radio-over-fiber and a new digital fronthaul in a chromatic dispersion-limited scenario. The former uses several analog channels, generated by up- and down-converting of baseband signals, and the latter utilizes simple OOK NRZ for the transmission to the remote radio head. Both principles are applied to a custom millimeter-wave system, consisting of several analog channels with baseband bandwidths as expected for 5G. The performance of both concepts at transmission rates of up to 100 Gb/s and 100 km of fiber is evaluated. We will show that both approaches are suitable for transmission distances typical for fronthaul and discuss their advantages and disadvantages. Furthermore, an optimized bandwidth concept for the analog radio-over-fiber system is presented, which enables transmission distances on the scale of metro networks.","Title: Optical Wireless MIMO Experiments in an Industrial Environment.\nYear: 2018\n\nAbstract: This paper reports on a field trial in a robotic manufacturing cell. Channel measurements and transmission experiments were conducted, assisting the development of a light-emitting diode-based optical wireless communication (OWC) system tailored for the needs of industrial wireless applications. These are moderate data rates, reliability, and low latency. Since dedicated radio spectrum is hardly a...","Title: Digital-to-Analog Converters Using Frequency Interleaving: Mathematical Framework and Experimental Verification.\nYear: 2018\n\nAbstract: The concept of frequency interleaving (FI) for digital-to-analog converters (DACs) has recently experienced renewed interest, in order to overcome the DACs’ bandwidth limitations. In this concept, the output signals of multiple DACs are interleaved in the frequency domain in order to generate a combined output signal that exceeds both the sampling rate and the bandwidth of a single DAC. In this paper, a mathematical framework for FI-DACs with a large number of DACs is presented and the inherent interdependencies between sampling rate, the number of samples, LO frequencies, symbol rate and analog frequency responses are highlighted. A mathematical expression for the distribution of data samples among the DACs is presented, taking into account bandwidth limitations of the analog components as well as guard bands to mitigate cross talk. In order to balance the FI-DAC’s parameters a mathematical optimization approach is introduced and illustrated with examples. Both simulation and experimental results validate the FI-DAC concept, and an outlook on implementation issues completes this paper.","Title: A Converged Evolved Ethernet Fronthaul for the 5G Era.\nYear: 2018\n\nAbstract: We assess the performance of two distinct functional splits based on latency/latency variation and mapping efficiency, both individually and in unison. By considering hardware-offloading possibilities for a low-layer split (especially a pre-resource mapper split) using an option-6 software-based local thermal equilibrium split as an example, we show how data rate, Ethernet frame size and, in gener...","Title: Channel measurement campaigns for wireless industrial automation.\nYear: 2019\n\nAbstract: The factories of the future will be highly digitalized in order to enable flexible and interconnected manufacturing processes. Especially wireless technologies will be beneficial for industrial automation. However, the high density of metallic objects is challenging for wireless systems due to multipath fading. In order to understand the signal propagation in industrial environments, this paper provides results from a number of channel measurement campaigns funded by the German research initiative \"Reliable wireless communication in the industry\". We give an overview of different measurement scenarios covering visible light communication and radio communication below 6 GHz. We analyze large and small scale parameters as well as delay statistics of the wireless channels. Finally, we discuss the importance of the results for the definition of industrial channel models.","Title: High Speed 160 Gb/S Dmt Vcsel Transmission Using Pre-Equalization\nYear: 2017\n\nAbstract: High speed single channel DMT operation of a directly modulated 850 nm VCSEL with 26 (31-1z bandwidth is presented. Successful transmission of 161. 152, 135 Gb/s over 10, 300, 550 m of 0M4 MMF is demonstrated at the SD-FEC FIER limit.","Title: 100g Ofdm-Pon For Converged 5g Networks: From Concept To Real-Time Prototype\nYear: 2017\n\nAbstract: We propose an implementation concept for a 100E OFDM-PON for a converged 5G network. A real-time OLT prototype and ONU detection with partial bandwidth are presented.","Title: Long-Term Outdoor Measurements Using A Rate-Adaptive Hybrid Optical Wireless/60 Ghz Link Over 100 M\nYear: 2017\n\nAbstract: In this paper, we evaluate the potential of a rate-adaptive hybrid link, combining LED based optical wireless and 60 GHz technologies. These links over short backhauling distances are well suited for the deployment of small radio cells in 5G mobile networks. Results from a 4.5-month outdoor field trial indicate that the availability for both links is 100%. The throughput of the LED-based optical link is higher in 90% of all cases while the 60 GHz link has a higher minimal throughput. If both links are aggregated, the hybrid link offers minimal/average/maximal data rates of 230/750/880 Mbps over 100 m in all weather conditions.","Title: Ultra-Low Latency 5g Charisma Architecture For Secure Intelligent Transportation Verticals\nYear: 2017\n\nAbstract: We describe low end-to-end latencies of 6.69 ms in the 5G CHARISMA network, that has been optimised for both device and system technologies speed, as well as with its virtualised, hierarchical and distributed, edge-centric architecture, that processes data as near as possible to their source and destination. Such an ultra-high speed 5G network can be utilised in intelligent transport system (ITS) applications, and we describe a public transport bus-based use case that takes advantage of the CHARISMA capabilities.","Title: Bandwidth Extension Techniques For High-Speed Access Networks\nYear: 2018\n\nAbstract: Recent advances in bandwidth extension techniques for high-speed access environments are presented together with own transmission experiments. Current issues and critical aspects are highlighted.","Title: Next-Generation Optical Fronthaul In The Icirrus Project\nYear: 2018\n\nAbstract: We discuss next-generation fronthaul solutions for 5G and legacy radio access networks. Architectures, findings and experimental results from recent lab and field trial activities are reported. (C) 2018 The Author(s).","Title: Use Cases for Optical Wireless Communication\nYear: 2018\n\nAbstract: We present results from trials in three promising uses cases for optical wireless communication (OWC): Mobile backhaul, industrial wireless, and indoor Li-Fi. We point out specific requirements and illustrate performance through measurements in typical scenarios.","Title: Boosting 5G Through Ethernet: How Evolved Fronthaul Can Take Next-Generation Mobile to the Next Level\nYear: 2018\n\nAbstract: Current approaches to the fronthaul for centralized, or cloud, radio access networks (C-RANs) need to be revised to meet the requirements of next-generation mobile networks. There are two major challenges. First, fronthaul signals need to be transported over public fixed-access networks, such as passive optical networks (PONs), typically sharing them with other services. Second, higher data rates ...","Title: Bandwidth Enhancement For An Optical Access Link By Using A Frequency Interleaved Dac\nYear: 2018\n\nAbstract: We present the experimental realization of the frequency interleaved DAC concept for an IM/DD based access link. The first open 80 GBd PAM-4 electrical eye diagram of the frequency-interleaved DAC without using post-equalization is presented.","Title: Real-Time Optical Wireless Communication: Field-Trial in an Industrial Production Environment\nYear: 2018\n\nAbstract: We present the first field-trial of a real-time optical wireless communication (OWC) system in an industrial manufacturing environment. Using spatial diversity schemes, we demonstrate how OWC can provide reliable low-latency communication despite the rapid movements of a production robot.","Title: Behavioral Model for a High-Speed 2:1 Analog Multiplexer\nYear: 2018\n\nAbstract: A novel concept for digital-to-analog converters (DACs) has been introduced recently, to overcome their bandwidth limitations by combining the outputs of multiple DACs with an analog multiplexer (AMUX). In this paper, a behavioral model for a high-speed 2: 1-AMUX is introduced, which significantly reduces the simulation time for a 2: 1-AMUX-DAC system. The behavioral model is implemented in Matlab and fitted with simulation data from an electronic design automation tool for a high-speed 2: 1-AMUX integrated circuit with a normalized mean square error < -20 dB. Eventually, multiple model parameters are varied in order to study their impact on the system's behavior.","Title: Testbed Verification of New Fronthaul Technology for 5G Systems\nYear: 2019\n\nAbstract: The fronthaul for 5th generation mobile systems (and beyond) has evolved with new splits for the radio access network functions defined, and the transport for these split interfaces having very different requirements. Testing of the transport for such split interfaces is reported, and it is shown that an Ethernet fronthaul transport network, which is capable of bringing efficiency gains through statistical multiplexing, can meet stringent latency and latency variation requirements, assuming buffering and playout of the radio waveforms and that timing/synchronization signals are prioritized. An aggregation technique for a 100 Gb/s Ethernet trunk which provides for such timing signals is demonstrated. Real-time monitoring of the Ethernet fronthaul for software-defined networking control and performance optimization is also shown.","Title: Benefits of MIMO Mode Switching, Angular Diversity and Multiuser Multiplexing for LiFi\nYear: 2021\n\nAbstract: We report on the first real-time experiments with distributed MIMO and multiple users for LiFi. MIMO mode switching and angular diversity are beneficial for robustness. Multiuser multiplexing helps in scenarios where users have complementary MIMO channels. (C) 2021 The Author(s)","Title: ELIoT: New Features in LiFi for Next-Generation IoT\nYear: 2021\n\nAbstract: The Internet of Things currently is predominantly narrowband and cannot always guarantee high reliability and low latency. Future IoT applications such as flexible manufacturing, augmented reality and self-driving vehicles need sophisticated real-time processing units in the cloud to which mobile IoT devices are connected. These high-capacity links meet the requirements of the upcoming 6G systems and cannot be facilitated by the current mobile communication infrastructure. Light communication, which is also denoted as LiFi, offers huge amounts of spectrum, extra security and interference-free transmission. We present the current state-of-the-art of LiFi systems and introduce new features needed for future IoT applications. We propose a distributed Multiple-Input Multiple-Output topology with a fronthaul using plastic optical fiber. Such a system offers seamless mobility between the light access points and also to 5G, besides low latency and integrated positioning. Future LiFi development, implementation and efforts towards standardization are addressed in the EU ELIoT project which is presented here.","Title: Fiber-based Frequency Modulated LiDAR With MEMS Scanning Capability for Long-range Sensing in Automotive Applications\nYear: 2021\n\nAbstract: Safe operation of driver assistance systems, especially at higher speeds, remains a challenge. For this automotive application, we propose a long-range coherent LiDAR system concept with two-dimensional micro electro-mechanical system (MEMS) scanning and sparse sensing capability. We address system design challenges for the transmitter, the fiber-based optics and coherent receiver, and the impact ...","Title: All-Indoor Optical Customer Premises Equipment for Fixed Wireless Access\nYear: 2021\n\nAbstract: We demonstrate an LED-based optical wireless link for fixed wireless access applications, at data rates of 1.5 Gbit/s over 50 m. Transmission between indoor equipment and outdoor access point is possible through metal-coated insulation glass.","Title: Hy-Fi: Aggregation of LiFi and WiFi using MIMO in IEEE 802.11\nYear: 2021\n\nAbstract: We present Hy-Fi, a system which combines light fidelity (LiFi) and radio based on the WiFi physical layer waveform by using the MIMO features available in IEEE 802.11-compliant commodity chip sets. Hy-Fi is based on two key ideas. First, we use inexpensive COTS hardware to facilitate direct transmission of WiFi waveforms over the optical wireless channel, as this is proposed in the IEEE P802.11bb...","Title: LiFi based Positioning for Indoor Scenarios\nYear: 2021\n\nAbstract: An indoor positioning system integrated with wireless communication is an essential tool for future Internet of Things applications. This paper presents a time-of-flight-based positioning approach based on networked optical wireless communication, which is also known as LiFi. Our proposed system is based on the ITU-T G.9991 standard and enables positioning besides communication using the existing ...","Title: An Efficient Multi-Link Channel Model for LiFi\nYear: 2021\n\nAbstract: In this paper, we report for the first time on a new channel modelling technique for multi-link LiFi scenarios. By considering simplified numerical calculation, it models the links between multiple optical frontends and multiple mobile devices much faster than previous approaches. For the first two diffuse reflections, we replace ray tracing method by frequency domain channel modelling technique. For the other higher order diffuse reflections, we use a well-established model based on the integrating sphere. For validation of our new approach, we performed distributed 4x2 MIMO channel measurements. Comparison of simulation and measurement yields a relative mean square error below 5 percent for the signals with a free line-of-sight. Our new technique enables efficient modeling of mobile scenarios and analyzing statistical properties of the LiFi channels.","Title: Efficient Line Coding for Low-Power Optical Wireless Communications\nYear: 2021\n\nAbstract: Optical wireless communications gains new interest in the recent years, due to high potential for use cases in the industrial internet of things. In order to address lower power consumption requirements at the mobile transmitter, an on-off-keying based physical layer has been developed by the IEEE task group 802.15.13, supporting a wide range of symbol rates from 12.5 to 200 MBaud. While providing robustness against high-pass filtering effects in analogue optical frontends, the currently used 8b10b line-coding causes a large overhead, notably limiting the achievable throughput. In this work, we investigate scrambler-based alternatives for the line-coding that reduce overhead at the cost of less-balanced signaling. We analyze statistical properties and thoroughly test the performance using a frontend-model derived from measurements on an optical frontend prototype. Accordingly, the 64b67b scheme is proposed as an optional line coding in the IEEE P802.15.13 project.","Title: Analog 2:1 Multiplexer with over 110 GHz Bandwidth in SiGe BiCMOS Technology\nYear: 2021\n\nAbstract: We report on a 2:1 analog multiplexer (AMUX) circuit in 130-nm SiGe BiCMOS technology. The technology offers HBTs with peak fT of 470 GHz and fmax of 650 GHz. S-parameter measurements of the AMUX IC show a significant leap in bandwidth compared to the circuit in the previous technology generation. The linear signal path offers a 3-dB-bandwith beyond 110 GHz, while the limitin...","Title: LIDAR-Assisted Channel Modelling for LiFi in Realistic Indoor Scenarios\nYear: 2022\n\nAbstract: We present a new, accurate, low complexity channel modelling methodology for LiFi in realistic indoor scenarios. A LIDAR scanner is used to capture the 3D environment in which the LiFi system is to be deployed. Next, the generated 3D point cloud data is pre-processed to determine the reflectance parameters of the walls and objects in the room. This is easier and more realistic than the manual definition of the environment, which is the current state of the art. As an additional innovation, the complexity of the channel modelling is reduced by: 1) modelling the line-of-sight and initial reflections precisely in the frequency-domain; 2) using a well-established analytical model based on the integrating sphere for all higher-order diffuse reflections. All steps together yield a substantially simplified channel modelling approach and model the links between multiple optical frontends and multiple mobile devices realistically. As a validation of our new approach, we compare measurements and simulations in two indoor scenarios: an empty room and a conference room with furniture. Simulations and measurements show excellent agreement with a mean square error below 3 percent. Moreover, we evaluate the performance of a distributed multiuser multiple-input multiple-output (MIMO) link and found excellent agreement between the model and measurements. Finally, we discuss the fundamental trade-off between complexity and model error, which depends on the scenario.","Title: LIDAR-Assisted Channel Modelling for LiFi\nYear: 2022\n\nAbstract: We present fast and accurate modelling of LiFi channels using data from LIDAR scans. Line-of-sight, first and residual reflections are modelled in the frequency-domain and using the integrating-sphere method. Model and measurement show good agreement. (C) 2022 The Author(s)","Title: LiFi with 5G for the Smart Factory\nYear: 2022\n\nAbstract: The ongoing shop floor digitalization confronts manufacturers with challenges in computer networks. Wi-Fi became a standard for enabling mobile applications in factories but suffers from operating in the shared industrial, scientific and medical (ISM) radio band, which makes Wi-Fi networks prone to interference from wireless networks that operate in parallel. Consequently, Wi-Fi is a less reliable wireless network technology for smart factories. LiFi and 5G are alternatives that do not rely on ISM bands. With a combination of 5G and LiFi we reach flexibility, reliability, wide coverage, and high throughput for fixed and mobile devices in factories. In this paper, we demonstrate the use of LiFi as a non-3GPP access technology for the 5G core network and describe our initial testing of the N3IWF implementation. Besides, this paper describes a multistage demonstrator set-up, which allows to conduct initial validation tests in a distributed testbed environment. This approach enables the direct migration of developed system components into a real factory environment considering the rough environment of manufacturing halls.","Title: An Energy-Efficient Optical Wireless OFDMA Scheme for Medical Body-Area Networks\nYear: 2022\n\nAbstract: The transfer of health monitoring data from multiple patients using wireless body-area networks requires the use of robust, and energy and bandwidth efficient multiple-access schemes. This paper considers the frequency-division multiple access for the wireless uplink to a fixed access point when using infrared signals to collect medical data from several patients inside an emergency waiting room. The conventional optical orthogonal scheme applies Hermitian symmetry to obtain real-valued signals, which implies increased computational complexity. We consider a new approach transmitting only the real part of a complex-valued signal, where no such constraint is imposed. Based on the proposed scheme, and taking into account the limited dynamic range of an infrared light-emitting diode, we study the performance of direct current biased and asymmetrically clipped schemes, and show their advantage in terms of energy efficiency and computational complexity, as compared with the conventional schemes. For instance, we show that by using asymmetric clipping, around 35mW less transmit power is needed to achieve a bit error rate of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\mathrm {10}^{-3}$ </tex-math></inline-formula>\n in the considered scenario. We also demonstrate the robustness of the proposed scheme against multiple access interference.","Title: Techno-Economics of LiFi in IoT Applications\nYear: 2022\n\nAbstract: This paper describes the first techno-economical study for the deployment of very dense wireless networks for new Internet of things (IoT) applications. We propose mobile optical wireless communication (OWC) also known as light fidelity (LiFi) because it offers unique advantages for the IoT such as robustness through exclusive channel access in the unlicensed optical spectrum, lower latency, and enhanced security. We investigate the deployment of LiFi in an industrial scenario, as currently specified by ITU-T recommendation G.9991, including the required fixed backbone and assuming full coverage. We propose six different LiFi topologies and compare them in different industrial scenarios. The comparison is performed in terms of Bill of Material, and in terms of costs. We show that a fully wired topology requires higher installation costs but incurs in lower operational costs, resulting in lower total costs of ownership (TCO) than other wireless topologies. Furthermore, power consumption has been identified as the cost driver for all topologies (more than 200% of the initial investments), triggering the need for power-saving techniques. Last but not least, the separation of Optical Front Ends (OFEs) has been identified as a critical design parameter, as shorter separation requires higher costs but reduces the cost per delivered bitrate. We discuss promising ways for the deployment of very dense wireless networks as key to bringing LiFi into future IoT applications.","Title: Simultaneous Channel Estimation for Pulsed-Modulation Optical Wireless Communications\nYear: 2022\n\nAbstract: In this paper, suitable estimation sequences and algorithms for the simultaneous channel estimation in an optical wireless communication system are assessed. We focus on a multi-user-MISO setup and an on-off-keying based pulsed-modulation physical layer. The performance of the tested configurations is evaluated using simulations under the constraints of imperfect time synchronization between the transmitters and band-pass distortions. Furthermore, a new family of binary channel estimation sequences, named Variable Sampling Factor (VSF) sequences, is proposed with the goal of enabling simultaneous estimation even between terminals using different sample clock rates. Despite a high variance of channel gains in the used model, the best presented algorithm is able to detect 6 out of 8 transmitters on average.","Title: All-Optical Distributed MIMO for LiFi: Spatial Diversity Versus Spatial Multiplexing\nYear: 2022\n\nAbstract: LiFi or networked optical wireless communication is likely to play an important role in offloading mobile data traffic from radio into the optical spectrum. As the number of Internet of Things (IoT) devices is growing, the RF spectrum becomes a rare resource. Imaging IoT sensors like cameras, ultrasonic devices, and Lidars have real-time requirements, need a high-capacity uplink, and operate in environments that cause or are sensitive against electromagnetic interference. In this paper, for the first time, we present realtime communication over an all-optical fixed-wireless LiFi link based on the distributed multiple-input multiple-output concept. For distributing the wireless signals, plastic optical fibers are used as an analog front-haul. We study the operation of the distributed multiple-input multiple-output link in two modes, i.e., spatial diversity and spatial multiplexing. For the diversity mode, a new combiner is presented, which can support equal gain as well as selection combining. We demonstrate that selection combining is highly effective and enables a similar LiFi performance in up- and downlink, as it is desirable for industrial applications. For the spatial multiplexing mode, we observe that the channel rank and the achievable throughput depend strongly on the user location. As effective solutions, we study the benefits of angular diversity and multiple-input multiple-output mode switching together with multi-user multiplexing and conclude that a dynamic switching between spatial diversity and spatial multiplexing is a practical approach."],"string":"[\n \"Title: Scaleable network multicast for cooperative base stations\\nYear: 2008\\n\\nAbstract: Cooperative joint transmission and detection algorithms have a high potential to increase the capacity of cellular radio systems. This paper investigates efficient network layer protocols to realize such cooperation over a heterogeneous, bandwidth-limited backhaul. Target systems are MIMO-OFDM cellular communication systems with flat hierarchy (no central unit), and we take 3GPP LTE as example. The proposed architecture uses IP multicast for stations receiving the same information and is scaleable by dynamically cooperating only on frequency subbands. SINR and mobility thresholds are used to first cooperate for critical cell-edge users with low mobility, where most interference reduction gain is to be expected.\",\n \"Title: Adaptive Feedback Compression for Joint Transmission Coordinated Multi-Point.\\nYear: 2013\\n\\nAbstract: In this paper, we study adaptive feedback compression of explicit multi-cell channel state information (CSI) for joint transmission coordinated multi-point (JT CoMP) in future mobile networks. The scheme comprises of three steps: First, the strongest cells are clustered using a network-defined threshold. Next, the strongest taps are selected using a threshold related to noise and out-of-cluster interference. Finally, adaptive quantization is applied so that the channel mean square error (MSE) remains sufficiently small. We show that the number of quantization bits grows linearly with the signal to noise ratio (SNR) in dB, as required by information theory. Results indicate that explicit CSI from all relevant cells around a terminal can be provided using few kbits per reporting interval in 20 MHz bandwidth. The scheme is implemented and tested in real time.\",\n \"Title: Real-time signal processing for multiantenna systems: algorithms, optimization, and implementation on an experimental test-bed\\nYear: 2006\\n\\nAbstract: A recently realized concept of a reconfigurable hardware test-bed suitable for real-time mobile communication with multiple antennas is presented in this paper. We discuss the reasons and prerequisites for real-time capable MIMO transmission systems which may allow channel adaptive transmission to increase link stability and data throughput. We describe a concept of an efficient implementation of MIMO signal processing using FPGAs and DSPs. We focus on some basic linear and nonlinear MIMO detection and precoding algorithms and their optimization for a DSP target, and a few principal steps for computational performance enhancement are outlined. An experimental verification of several real-time MIMO transmission schemes at high data rates in a typical office scenario is presented and results on the achieved BER and throughput performance are given. The different transmission schemes used either channel state information at both sides of the link or at one side only (transmitter or receiver). Spectral efficiencies of more than 20 bits/s/Hz and a throughput of more than 150 Mbps were shown with a single-carrier transmission. The experimental results clearly show the feasibility of real-time high data rate MIMO techniques with state-of-the-art hardware and that more sophisticated baseband signal processing will be an essential part of future communication systems. A discussion on implementation challenges towards future wireless communication systems supporting higher data rates (1 Gbps and beyond) or high mobility concludes the paper.\",\n \"Title: On the Value of Synchronous Downlink MIMO-OFDMA Systems with Linear Equalizers\\nYear: 2008\\n\\nAbstract: Cellular radio systems are often limited due to the presence of cochannel interference. Basi- cally, radio systems may be operated by utilizing asyn- chronous or synchronous downlink transmission from all base stations in the system, where synchronization between terminals and their serving base station is mandatory in both concepts. We provide a comparison between the theoretical achievable spectral efficiency in an orthogonal frequency division multiple access sys- tems using different linear equalizers and their resulting performance taking estimation errors into account. It is shown, that the choice of the appropriate receiver depends on the degree of synchronization in the system. We demonstrate that a 3G Long Term Evolution radio system may achieve higher spectral efficiency thanks to interference suppression if fully synchronized data transmission from all base stations is introduced. I. Introduction Multi-cell interference is undoubtedly the major limiting factor in full-coverage broadband wireless access networks. Mitigating its effect onto the downlink data transmission is a key challenge in future wireless communication systems. The better the knowledge about the interference channels, the better is also the basis for any interference mitigation. Existing and future wireless standards, as 802.11n, WiMAX, 3G HSDPA and its long-term evolution (3G- LTE) have built-in means for multiple-input multiple- output (MIMO) signaling. Multi-antenna terminals enable interference suppression at the receiver side and thus the radio system may profit from a higher spectral efficiency. Simple receiver-based schemes like optimal interference rejection combining (1) are known to significantly increase the system's spectral efficiency (2). However, its appli- cability in MIMO-OFDMA systems is not fully evident yet, since it is highly sensitive to channel estimation errors. This work shows the spectral efficiency gains in an OFDMA system using the interference rejection combining (IRC) instead of the maximum ratio combining (MRC) receiver, while considering channel estimation errors. We always assume synchronization between mobile terminals (MTs) and their serving base station (BS) (3). The system parameters are chosen from the current draft specification of the 3G Long Term Evolution (3G-LTE) (4).\",\n \"Title: Localized SC-FDMA with constant envelope.\\nYear: 2013\\n\\nAbstract: Singe-carrier frequency-division multiple access (SC-FDMA) enables simplified equalization and flexible multiuser scheduling in the frequency domain. Compared to orthogonal frequency division multiple access (OFDMA), it has reduced envelope fluctuations in the same bandwidth. SC-FDMA is widely used in mobile communications, where the focus is on spectral efficiency. Here, we consider an evolution towards better energy efficiency. We propose evolved transmission schemes combining energy-efficient modulation and frequency-domain filtering. Using Gaussian minimum-shift keying (GMSK) and filtered pi/2 binary phase-shift keying (BPSK), the peak-to-average power ratio (PAPR) can be reduced down to 0 and 1.9 dB, respectively, while penalties at the receiver side are negligible.\",\n \"Title: Multiple CFOs in OFDM-SDMA uplink: interference analysis and compensation\\nYear: 2009\\n\\nAbstract: In OFDM-based space division multiple access (SDMA) systems, multiple users are served by a multiantenna base station simultaneously on the same frequency resources. In the uplink, each user's signal may be distorted by an independent carrier frequency offset (CFO), which impairs the orthogonality of the subcarrier signals and, if not properly compensated, results in performance degradations. We analyze the influence of multiusers' CFOs on the signal transmission in the OFDM-SDMA uplink and derive suitable bounds for the achievable signal-to-interference conditions. By modifying the signal model suitably, we develop a simple scheme for partial compensation of the CFO distortions. It allows to maintain the subcarrier-wise channel equalization and thus is well suited to be applied for a real-time system implementation. However, as CFOs impair the cyclic structure of the OFDM symbols, our scheme is not able to compensate for the entire distortion. The remaining interference is treated as additional noise, which limits the supported size of the CFOs.\",\n \"Title: A channel model for wireless infrared communication.\\nYear: 2000\\n\\nAbstract: An simple analytic model for the light propagation in indoor environments is presented. Ray tracing simulations confirm that the model is applicable to the wireless infrared communication channel in rooms.\",\n \"Title: 12x12 MIMO-OFDM Realtime Implementation for 3GPP LTE+ on a Cell Processor.\\nYear: 2008\\n\\nAbstract: We present a realtime implementation of the time-critical core functions for 12 x 12 MIMO-OFDM (12 data streams) with LTE parameters on a Cell Broadband Engine Processor. An MMSE equalizer matrix update interval of 1 ms (high mobility) is achieved with less than 50% CPU utilization. Concurrent bidirectional processing (precoding and postprocessing) is shown to be feasible with this update rate.\",\n \"Title: Interference-Aware Scheduling in the Synchronous Cellular Multi-Antenna Downlink\\nYear: 2009\\n\\nAbstract: Abstract—We consider the downlink of a multi-user MIMO OFDM system in a cellular environment, where users are scheduled to the transmission resources in frequency and space. Targeting a practical solution, we assume the use of fixed DFT- based pre-coding beams at the base stations and linear receivers at the multi-antenna terminals. After having received feedback on the frequency-selective interference conditions from all terminals, each base station schedules the terminals to their resources of highest quality while following a fair scheduling policy. It is shown that this rather simple practical concept enables spatial multiplexing transmission for all users in the system, in particular even for users at cell edge. This results in a capacity scaling that is similar to the one known for isolated point-to-point links. Finally, the system is shown to achieve a performance close to the ideal case if proper techniques to estimate the desired and interfering channels are applied.\",\n \"Title: Distributed Uplink Base Station Cooperation for Optimal SIR Assignment\\nYear: 2010\\n\\nAbstract: Base station cooperation is considered as a promising approach to increase the quality of service (QoS) in uplink. Base stations are connected via high-capacity backhaul links, which makes it possible to perform joint detection through information sharing among several base stations. Joint detection broadens the feasible signal to interference ratio (SIR) region, in which any SIR assignment for all users can be concurrently supported. Thus it provides a higher system throughput. We characterized the Pareto-optimal boundary of the feasible SIR region of power control with base station cooperation by utilizing the property of concave interference function. We suggest a distributed power control algorithm that exploits the broader feasible SIR region and optimizes the SIR assignment. Depending on the feasibility of the network to support cooperation, we analyze 3 degrees of cooperation: no cooperation, limited cooperation, and full cooperation.\",\n \"Title: REAL-TIME EXPERIMENTS ON CHANNEL ADAPTIVE TRANSMISSION IN THE MULTI-USER UP-LINK AT VERY HIGH DATA RATES USING MIMO-OFDM\\nYear: 2006\\n\\nAbstract: In this paper we focus on channel adaptive transmission in the multi-user OFDM Uplink where the base station uses multiple an- tennas. The additional degree of freedom in space requires extra signal processing effort which becomes challenging especially for a high data rate implementation in real-time. Our MIMO-OFDM experimental system which is capable to transmit data rates beyond 1 Gbit/s, was enhanced by adaptive re- source allocation, where the modulation on each antenna and each sub-carrier was controlled by a narrow-band feed-back channel. We present experimental results for the total rate achieved at the base station and the individual rates per user terminal in line- of-sight and non-line-of-sight scenarios. We compare the rates ex- pected from theory on the measured indoor channels with rates achieved in the experiments.\",\n \"Title: Polarization characteristics of multiple-input multiple-output channels\\nYear: 2008\\n\\nAbstract: In this paper, we investigate the polarization characteristics of the multiple-input multiple-output (MIMO) channels. The cross polarization discrimination (XPD) is found to change over time, while its variation in frequency domain is relatively small. The probability density function (PDF) of the XPD follows a Gaussian distribution. Analysis and measurement results show that the polarization preserves better in the line of sight (LOS) scenario. In the case of non line of sight (NLOS) scenario, the polarization of the signals is destroyed due to multiple reflections, diffractions or scattering. The difference between the XPDs of the vertically polarized and horizontally transmission highly depends on the specific propagation environment between the transmitter and the receiver. Comparison of the capacity in different scenarios further shows that the polarization diversity gain is less in NLOS scenarios compared with that in LOS scenarios.\",\n \"Title: Distributed Base Station Cooperation via Block-Diagonalization and Dual-Decomposition\\nYear: 2008\\n\\nAbstract: It has been recently shown that base station cooperation may yield great capacity improvement in downlink multiple antenna cellular networks. However, the proposed solutions assume that there is a central processing unit which coordinates the information exchange and determines the optimal resource allocation of the overall cellular network. Whilst the benefits of base station cooperation are large, computational burden of the central unit can be significant. Thus distributed solutions are desirable. This paper suggests a distributed solution for base station cooperation via block-diagonalization and dual-decomposition to maximize the weighted sum network capacity under per-antenna power constraint. The block-diagonalization pre-coding matrix is determined separately at each base station. It enables the full potential of base station cooperation by determining a trade-off between inter-cell interference mitigation, spatial multiplexing and macro diversity. The power allocation problem is formulated as a network utility maximization ( NUM) problem. By looking at its Lagrangian dual problem, the decomposable structure of the optimization problem is revealed. This leads to a distributed and iterative algorithm that converges to the global optimum. The advantage of macro diversity in addition to inter-cell interference mitigation and spatial multiplexing in base station cooperation context is studied and shows superior performance in terms of a higher capacity increase with lower variance. (1)\",\n \"Title: Interference Management For Future Cellular Ofdma Systems Using Coordinated Multi-Point Transmission\\nYear: 2010\\n\\nAbstract: Todays cellular systems reach their limits for data rate due to the continuously increasing amount of subscribers using wireless service for business purposes or in leisure time (smartphone effect) Thus re cent research focuses on concepts for interference management for cellular OFDMA systems This paper addresses various techniques related to this topic while considering the concepts with lowest complexity and backhaul costs as promising candidates to be applied first Starting from interference canceling receivers over multi user MIMO using fixed precoding to multi cell interference estimation which improves the precision of link adaptation we discuss closed loop cooperative transmit beamforming using multiple base stations grouped into a wireless distributed network (WDN) which is denoted as coordinated multi point Joint transmission in the 3GPP LTE Advanced standardization It is obvious the more sophisticated these techniques are the higher the demands for feedback and backhaul become Performance results are provided by employing multi cell simulations according to recommendations from 3GPP In addition feasibility of coordinated multi point joint transmission is demonstrated in a real time proto type setup ie in the Berlin LTE Advance Testbed\",\n \"Title: Acoustic Channel Model For Adaptive Downhole Communication Over Deep Drill Strings\\nYear: 2013\\n\\nAbstract: For reducing costs in drilling technology, seismic prediction while drilling (SPWD) is envisioned. SPWD needs a fast data link bringing up the seismic data from bottomhole to the ground. In this paper, we propose a flexible and easy-to-use acoustic channel model for long drill strings. The model enables efficient design of adaptive OFDM communication links and prediction of achievable data rates for variable string dimensions. We describe acoustic wave propagation by the S-parameters of the drill string modelled as a series of alternating short and long resonators due to segments of constant acoustic impedance. All segments have been parametrised and the final channel is a concatenation of all its segments. We verify the new model by comparison with measurements on a 55 m long drill string. By using our model, the properties of a manifold of real drill pipes with variable dimensions can be predicted. We investigate the impact of length variations typical for rough drilling applications. For efficient communications over 1.5 km, length variations of the screwed tool joints should be limited to a few centimetres while the pipe length may vary up to one meter.\",\n \"Title: A closed concept for synchronization and cell search in 3GPP LTE systems\\nYear: 2009\\n\\nAbstract: In this paper we investigate the time and frequency synchronization as well as the sector and cell search for the 3GPP Long Term Evolution (LTE) downlink. The proposed algorithms rely on the synchronization and cell-specific reference signals and are hence compliant to most recent 3GPP specifications. Time and (fractional) frequency offset coarse synchronization are performed in the time domain with the cyclic prefix based autocorrelation, while the sector and cell as well as the integer frequency offset are estimated in the frequency domain by using the primary and secondary synchronization signals. To improve the cell detection reliability, the estimated cell is afterwards confirmed through the cell-specific reference signal. All algorithms are evaluated under multipath channel conditions and an initial carrier frequency mismatch. Compromising high performance with reasonable implementation complexity, we draw a practical solution for an LTE receiver.\",\n \"Title: On Hardware Implementation Of Multiuser Multiplexing For Sc-Fdma\\nYear: 2007\\n\\nAbstract: A simple algorithmic scheme is proposed which calculates multiple variable-length FFTs/IFFTs at once by a single fixed-length one. The algorithm exploits the fact that the transform of a periodic signal is a line spectrum, the linearity property of FFT/IFFT and the shift theorem. The overall algorithm complexity is higher than calculating separate variable-length transforms, but the ease of implementation makes the scheme well-suited for FPGA based rapid prototyping systems. Because in SC-FDMA systems multiple variable-length transforms are needed for different users, the algorithm can be used to implement multiuser multiplexing. The scheme can be applied to DFT/IDFT as well as FFT/IFFT implementations.\",\n \"Title: Polarization rotation evaluation for macrocell MIMO channel\\nYear: 2009\\n\\nAbstract: In this paper, the impact of the polarization on the performance of the multiple-input multiple-output (MIMO) channel with cross-polarized antennas has been investigated based on the outdoor macrocell measurement at 2.53 GHz. A simple model which can capture the major characteristics of the cross polarized channel is proposed. The effective polarization rotation during the propagation is evaluated using the proposed model, and found to follow a bimodal Rayleigh distribution. The commonly accepted uniform distribution polarization rotation angle is a reasonable but coarse assumption compared with our estimated results. The vertical and horizontal polarization perform similarly in line-of-sight (LOS) scenario, but may be different in non-LOS (NLOS) scenario depending on the environment where the receiver is located. The polarization diversity outperforms the spatial diversity in LOS scenario, but shows relatively small gain in a rich scattering scenario. This is further proofed by the comparison of the capacity of a 4 × 4 MIMO channel with cross-polarized antennas.\",\n \"Title: Implementation Of Channel Aware Scheduling And Bit-Loading For The Multiuser Simo Mac In A Real-Time Mimo Demonstration Test-Bed At High Data Rate\\nYear: 2004\\n\\nAbstract: In this paper we discuss a cross layer approach to apply channel aware scheduling for a multi user SIMO multiple access channel. We show how optimum power and rate allocation can be achieved when successive interference cancellation (SIC) and a MMSE receiver is used at the base station. Combining this capacity optimum results with quality of service requirements of the users (e.g. data rate or delay) we analyze the Joint optimization problem and propose a suboptimum hut applicable scheduling approach which can he implemented already. today on real time capable hardware. Different scheduling policies were implemented in the real time MIMO test-bed in our lab. We describe the particular hardware setup for the experiments and present measurement results on various scheduling policies under power and bit error rate constraints with an average up-link spectral efficiency of tip to 17 bits/s/Hz with 3 base station antennas.\",\n \"Title: Practical Channel Interpolation For Ofdma\\nYear: 2006\\n\\nAbstract: This paper addresses piecewise frequency domain interpolation for OFDMA channels when raw estimates are given on a sparse grid of pilot carriers in a fraction of the spectrum only. Starting from the optimal linear interpolation which needs a-priori information on the power delay profile and the SNR, we develop robust suboptimal schemes that do not require such information. One scheme is based on singular value decomposition and it allows the estimation of the SNR. In practice, however, it is difficult to obtain the required information on the power delay profile. To ensure robustness of the filter to mismatched channel parameters, a favorable assumption of the power delay profile is suggested for the filter design. It is further shown that a full-spectrum interpolation assembled from multiple piecewise interpolation results has a dramatically reduced complexity which makes it suitable for real-time implementation.\",\n \"Title: Interference-aware scheduling in the multiuser MIMO-OFDM downlink\\nYear: 2009\\n\\nAbstract: With the introduction of orthogonal frequency-division multiplexing and multiple antennas in cellular networks, there are new opportunities to adapt the transmission to propagation and interference conditions. In this article we describe a practical approach using space-frequency-selective multiuser MIMO scheduling. Frequency-selective feedback is provided on achievable data rates for preferred single- and multistream transmission modes. The base station selects the best mode while providing instantaneous fairness. We observe that multiuser transmission increases the probability of using multistream transmission. Besides the benefits from optimal combining at the physical layer, there is an additional gain at the MAC layer since the estimation of achievable rates becomes more precise. Altogether, 93 percent of the theoretical throughput can be realized by synchronizing the base stations and providing cell-specific reference signals. We have implemented essential functions of the approach in real time on an experimental 3GPP LTE prototype in 20 MHz bandwidth. Feasibility of the key features is proven in laboratory and field trials.\",\n \"Title: Modeling and Measurement of MIMO Relay Channels\\nYear: 2008\\n\\nAbstract: This paper proposes a relay channel model which takes into account the influence of relay location and antenna configuration. Simulation results show that when relay is in the line-of-sight (LOS) propagation environment, the channel capacity will degrade. To improve the performance of the channel, water-filling (WF) algorithm is used to allocate the power, simulation results shows that the WF-based relay channel outperforms the uniform power allocation channel. The radiation pattern of the relay antenna is also an importance factor which affects the channel capacity in this case. The widely used Rayleigh channel model overestimates the performance of the channel compared with our model when the location of the relay is not in the scenario where Ricean K-factor is zero. Measurements have been done at 2.53 GHz to investigate the above-rooftop and ground-level relay channels. Results indicate that above-rooftop deployment is very efficient to improve the capacity and coverage.\",\n \"Title: On the Capacity of Intensity-Modulated Direct-Detection Systems and the Information Rate of ACO-OFDM for Indoor Optical Wireless Applications.\\nYear: 2012\\n\\nAbstract: In this paper we derive information theoretic results for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) in an intensity modulated direct detection (IM/DD) optical communication system subject to a range of constraints. ACO-OFDM is a form of OFDM designed for IM/DD systems. It is an effective solution to intersymbol interference (ISI) caused by a dispersive ch...\",\n \"Title: Implementation of adaptive channel inversion in a real-time MIMO system\\nYear: 2004\\n\\nAbstract: The implementation of adaptive channel inversion into a real-time single carrier MIMO test-bed is reported for the first time. Since no joint detection is possible at the distributed users, all signal preprocessing is performed at the transmitter which adapts the transmission links to all the mobile terminals depending on the actual channel situation. This means that the number of reliably supportable users is controlled as well as the modulation, ensuring BER targets for all users. The implemented algorithms are described and measurement results have shown the stable sum rate throughput of several 10 Mbit/s for a MIMO base station with 4 transmit antennas which supports up to 4 mobile terminals simultaneously. Since the transmission is based on optimum feedback of the channel knowledge to the transmitter, the results given here can be understood as a kind of an upper practical performance bound for the application of linear channel pre-distortion.\",\n \"Title: Flexible demonstrator platform for cooperative joint transmission and detection in next generation wireless MIMO-OFDM networks\\nYear: 2008\\n\\nAbstract: This paper presents a flexible demonstrator platform for cooperative joint transmission and detection in next generation wireless networks, especially cellular networks like 3GPP LTE+. The platform is shown capable of handling computational load as well as network load of jointly processing three maximum bandwidth LTE sectors with four antennas each. The platform uses a Workstation mainboard as PCI Express backplane. Joint signal processing is done on a Cell processor, protocol handling on an IXP2350 network processor. For baseband sample exchange a 10GBit/s optical network interface card is used. First results show the Cell processor capable of computing the 12x12 modified LTE MIMO-OFDM processing concurrently for precoding (downlink) and postprocessing (uplink) with a MIMO matrix update interval of 1ms (high mobility).\",\n \"Title: Capacity Measurements in a Cooperative MIMO Network\\nYear: 2009\\n\\nAbstract: Cooperation between adjacent base stations (BSs) may reduce intercell interference in future cellular networks and enhance network capacity in this way. The potential of cooperation is evaluated in this paper based on measurements conducted at 5.2 GHz in a campus environment with four overlapping cells. For each individual link of the four BS and five terminal locations, a 10 times 16 antenna conf...\",\n \"Title: Capacity Measurements In A Multicell Mimo System\\nYear: 2006\\n\\nAbstract: In future wireless networks, cooperation between the base stations may reduce the effects of intercell interference and enhance the capacity per cell. In this paper, the potential of such cooperation is evaluated using measurements of the information-theoretic channel capacity at 5.2 GHz in 4 overlapping urban macrocells with 5 users. In each link, a 10-transmit 16-receive antenna configuration is used.Results for individual links between terminals and base stations, valid for 60% of the scenarios, indicate that the direct signal has a significant impact on the channel structure. The direct signal contributes two spatial degrees of freedom due to the polarization. Rich scattering is observed when the direct signal is blocked.Results for the multiuser multicell scenario demonstrate for the first time experimentally that the intercell interference leads to an enhanced rank of the joint multiuser multicell channel matrix. Compared to a conventional cellular system, where a fixed assignment of different radio resources is used in adjacent cells in order to avoid the interference, it is better to exploit the interference by cooperation. This enhances the spectral efficiency by a factor of five in our measurement scenario.\",\n \"Title: The role of small cells, coordinated multipoint, and massive MIMO in 5G.\\nYear: 2014\\n\\nAbstract: 5G will have to support a multitude of new applications with a wide variety of requirements, including higher peak and user data rates, reduced latency, enhanced indoor coverage, increased number of devices, and so on. The expected traffic growth in 10 or more years from now can be satisfied by the combined use of more spectrum, higher spectral efficiency, and densification of cells. The focus of ...\",\n \"Title: Design of a visible-light-communication enhanced WiFi system.\\nYear: 2015\\n\\nAbstract: Visible light communication (VLC) has wide unlicensed bandwidth, enables communication in radio frequency (RF) sensitive environments, realizes energy-efficient data transmission, and has the potential to boost the capacity of wireless access networks through spatial reuse. On the other hand, WiFi provides more coverage than VLC and does not suffer from the likelihood of blockage due to the light of sight (LOS) requirement of VLC. In order to take the advantages of both WiFi and VLC, we propose and implement two heterogeneous systems with Internet access. One is the hybrid WiFi-VLC system, utilizing unidirectional VLC channel as downlink and reserving the WiFi back-channel as uplink. The asymmetric solution resolves the optical uplink challenges and benefits from the full-duplex communication based on VLC. To further enhance the robustness and increase throughput, the other system is presented, in which we aggregate WiFi and VLC in parallel by leveraging the bonding technique in Linux operating system. Online experiment results reveal that the hybrid system outperforms the conventional WiFi for the crowded environments in terms of throughput and web page loading time; and also demonstrate the further improved performance of the aggregated system when considering the blocking duration and the distance between access point and user device.\",\n \"Title: Adaptive Modulation and Turbo Coding for 3GPP LTE Systems with Limited Feedback\\nYear: 2014\\n\\nAbstract: Link adaptation is recognized as a powerful tech- nique for enhancing spectral efficiency over wireless channels. While its theoretical aspects are well understood, it is not clear yet how to practically deal with limited feedback. In this paper, we study a frequency-selective link adaptation scheme for orthogonal frequency division multiplexing (OFDM). The modulation order is adjusted per resource block (smallest time-frequency unit assigned to a user), while a joint coding rate is used for all variable-length codewords, comprising resource blocks with different modulations. In order to meet the required coding rate, adaptive puncturing is applied after a fixed-rate Turbo encoder. Link adaptation is guided by an effective signal-to-noise ratio (SNR), which is calculated over several subcarriers by a mapping function. 3GPP LTE compliant link-layer simulations were performed for optimizing the SNR interface so that the spectral efficiency is maximized under a codeword error rate constraint and tradeoffs between feedback savings and spectral efficiency losses were elaborated. The result is a thoroughly tested link-layer abstraction for 3GPP LTE including adaptive modulation and bit-interleaved coding that can be also used for system-level simulations towards future mobile radio systems.\",\n \"Title: Zero forcing equalizing filter for MIMO channels with intersymbol interference\\nYear: 2002\\n\\nAbstract: Equalization in the time domain is a well- known technique for combating intersymbol interference (ISI) in frequency selective channels. In this paper we derive the general structure of the linear zero forcing (ZF) equaliz- ing filters for multiple input multiple output (MIMO) com- munication systems with more outputs than inputs. These filters are finite impulse response (FIR) filters in general and their structure is determined by the number of inputs and outputs. The relation between the spatial diversity of the system and the necessary filter length is worked out and it is shown, that an optimal time lag in the filter will improve the performance considerably.\",\n \"Title: On linear pre-processing in multi-antenna systems\\nYear: 2002\\n\\nAbstract: We study linear pre-processing for multi-antenna systems when the channel is perfectly known at the transmitter. In particular, the capacity of linear and adaptive channel inversion is compared to the optimum water-filling. When equal numbers of antennas are used at the transmitter and at the receiver, the outage probability with linear inversion is rather large. Outage is remarkably reduced when more antennas are used at the transmitter. Adaptive inversion approximates the water-filling capacity at small transmitter power and so it is robust against fading correlation. The average transmitter power with linear inversion depends on the numbers of antennas at the transmitter and at the receiver. For Rayleigh fading, we compare the bit error performance to V-BLAST.\",\n \"Title: Limits of the achievable symbol rate in flat fading MIMO systems\\nYear: 2003\\n\\nAbstract: The irreducible error, introduced by the time dispersion of the radio channel for multiple-input multiple-output (MIMO) systems with flat fading detection algorithms are investigated analytically and by link level simulations. Using an adequate synchronisation method, the error floor is determined only by the intersymbol interference, for which a formula is derived. The maximal data rate is not only determined by the value of this interference, but also by the modulation scheme, antenna configuration and channel condition.\",\n \"Title: Performance of MIMO Rake receivers in WCDMA systems\\nYear: 2004\\n\\nAbstract: The rake receiver is investigated for spatial multiplexing (SM) in wide-band code-division multiple access systems. In general, the SM increases the data rate and the diversity order as well. The appropriate maximum likelihood detector is derived in this paper and it is shown that the diversity order is related to the product of the numbers of receive antennas and taps. With realistic numbers similar diversity orders may be achieved also with reduced complexity detection schemes. Finally, a standard-conformal scrambling technique is proposed to enhance the performance and to equalize it among the full set of orthogonal variable spreading factor (OVSF) sequences used in the third generation cellular system.\",\n \"Title: Statistics of the Ricean K-Factor at 5.2 Ghz in an Urban Macro-Cell Scenario\\nYear: 2006\\n\\nAbstract: In this paper we analyze 5.2 GHz channel measurement data in an urban macro-cell scenario in order to figure out the likelihood of a free line-of-sight and the statistics of the Ricean K-factor. We introduce a physical method to obtain this information from the Doppler delay spectrum taking GPS information into account. It is found, that for short distances the direct signal is available in 62% of all cases. However, the likelihood reduces at larger distances. In addition the average K-factor reduces with increasing distance. Measured distributions are fitted and parameters are provided for use in channel modelling\",\n \"Title: Effects of multiple users' CFOs in OFDM-SDMA up-link - an interference model\\nYear: 2006\\n\\nAbstract: OFDM-SDMA systems are intended to allow multiple users to communicate simultaneously with a base station in the same frequency band. In these systems, each user signal may be distorted by an independent carrier frequency offset (CFO), which will result in a severe degradation of the system performance if no CFO compensation is carried out. The standard compensation algorithms known from single-user SISO systems do not apply in this context, hence novel compensation techniques have to be introduced. We analyse the influence of multi-users' CFOs on the OFDM-SDMA signal transmission and develop a scheme for their compensation with low complexity. Due to a disturbance of the inherent structure of the OFDM system, the scheme is not capable to compensate for all the effects generated by the CFOs. The remaining interferences may be treated as additional noise, thus setting tight limits for the size of the CFOs which are supported by the system.\",\n \"Title: Joint Transmission and Detection in Hexagonal Grid for 3GPP LTE\\nYear: 2008\\n\\nAbstract: Cooperative joint transmission and detection algorithms have a high potential to increase the capacity of cellular radio systems. This paper proposes a mapping of areas of joint signal processing into the cellular hexagonal grid architecture, balancing network load, computational load and physical layer overhead versus interference reduction gain. The proposed communication architecture is shown to be realizable with off- the-shelf hardware.\",\n \"Title: Performance evaluation of a 3GPP LTE terminal receiver\\nYear: 2008\\n\\nAbstract: In this paper we present the evaluation of a receiver signal processing chain for a 3GPP long term evolution (LTE) terminal, including coarse synchronisation, channel estimation, fine syncronisation (tracking), MIMO equalization and detection. Algorithm blocks are first individually explained and simulatively evaluated with a realistic channel model. Adjustments of the blocks to each other for improved robustness are described, like interaction between time synchronization and channel estimation performance. After joint optimization, the performance of the complete chain is evaluated. Practical tradeoffs between complexity and performance are investigated and low-complexity algorithms are used. The presented receiver achieves an implementation loss of about 2 dB compared to perfect synchronization and channel estimation conditions.\",\n \"Title: Spatial Transmission Mode Switching in Multiuser MIMO-OFDM Systems With User Fairness\\nYear: 2010\\n\\nAbstract: Multiantenna radio systems allow accessing the channel in diversity or spatial multiplexing (SMUX) mode. Ade- quate switching between these modes according to current channel conditions was shown to yield significant performance improve- ments while requiring little feedback from the receiving side. We present a transmission concept for the downlink of a multiuser multiple-input-multiple-output orthogonal frequency- division-multiplexing (MU-MIMO-OFDM) system aiming at high user rates with limited feedback demands. An extended score-based scheduling (SB) approach ensures fair-resource allo- cation to the users, whereas transmission mode switching is used to guarantee high user rates. The degree of fairness of the scheduler can be adapted by adequately configuring a weighting function for the scores. Comparison with single-mode schemes reveals substantial throughput gains of the adaptive switching concept. Furthermore, targeting maximum throughput, we show that a considerable proportion of the capacity of the MIMO broadcast channel (BC) can be achieved with a comparatively low amount of required feedback. Index Terms—Multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM), multiuser systems, resource allocation, score-based scheduling (SB), spatial mode switching.\",\n \"Title: Channel Prediction by Doppler-Delay Analysis and Benefits for Base Station Cooperation\\nYear: 2013\\n\\nAbstract: Base station cooperation is a promising technique for next generation cellular systems as it reduces intercell interference. In this paper, we investigate to what extent performance degradation due to the feedback delay can be compensated by advanced channel prediction. We present a new method based on a Doppler-delay model of the time-variant radio channel. In a first step, significant channel taps are extracted in the delay domain. In a second step, a high-resolution algorithm extracts the major Doppler frequency components for each channel tap. In this way, a shorter history of the channel is needed, as compared to the standard discrete Fourier transform (DFT) technique. Prediction is performed by imposing the estimated parameters into the channel model and extrapolating into future. Evaluation over the extended spatial channel model (SCME) shows that the channel mean square error can be reduced by roughly 10 dB for feedback delays between 5 and 10 ms, which translates into signal to interference ratio (SIR) gains between 5 and 15 dB, also depending on the number of jointly served terminals. Finally, it is shown that, even if the channel state information (CSI) feedback is quantized, almost the same performance can be achieved as if based on perfect channel knowledge.\",\n \"Title: Analytical models for channel aging and synchronization errors for base station cooperation\\nYear: 2013\\n\\nAbstract: Base station cooperation is a powerful technique for eliminating inter-cell interference and enhancing spectral efficiency in cellular networks. However, impairment effects due to channel time variance, channel estimation, feedback quantization and imperfect synchronization among base stations are limiting the potential gains. In this paper, we present a comprehensive signal model for multi-user multi-cellular systems with cooperating base stations, which includes those essential impairments. The effect of each impairment is captured by its mean square error (MSE), for which exact analytical expressions and accurate approximations are derived and numerically verified. Those MSE expressions can be used for link-layer abstraction, system-level evaluation and signal to interference ratio (SIR) analysis. We evaluate the spectral efficiency of cooperative networks considering a real-world scenario and find that channel aging has the largest impact on performance degradation.\",\n \"Title: A UNIFIED FEEDBACK SCHEME FOR DISTRIBUTED INTERFERENCE MANAGEMENT IN CELLULAR SYSTEMS: BENEFITS AND CHALLENGES FOR REAL-TIME IMPLEMENTATION\\nYear: 2009\\n\\nAbstract: This paper contributes to the system concept of collaborative base stations from the perspective of distributed computing. Promising signal processing approaches based on terminal feedback are re- viewed. Their specific advantages and disadvantages are discussed and a framework for feedback provision is presented. All proposed schemes have in common, that a mobile terminal can choose its desired receive strategy independently from other mobile terminals according to its computational capabilities. The effective multi-cell channel after receiver processing is fed back and distributed within the collaboration area. This allows distributed processing at each base station and makes real-time implementation feasible.\",\n \"Title: Interference Limited MIMO Measurements\\nYear: 2010\\n\\nAbstract: We evaluate the interference limited spectral efficiency of a small cellular network using measurements with 3 sites at an ISD of 750 m. Each 3-sector site is equipped with cross-polarized panel antennas. We provide an efficient method to estimate the MIMO capacity from the measured data. We then compare the capacities of SISO and 2x2 MIMO with and without interference. At a fixed SNR of 10 dB, our cross-polarized interference free 2x2 setup achieves 5.7 bps/Hz which compares well to findings from Manhattan. For the best serving BS, the median 2x2 capacity including the received power and a reuse factor of 9 is 1.7 bps/Hz. This value increases to 3 bps/Hz when using frequency reuse 3 and 4.7 bps/Hz with full reuse.\",\n \"Title: Coexistence of WiFi and LiFi toward 5G: concepts, opportunities, and challenges.\\nYear: 2016\\n\\nAbstract: Smart phones, tablets, and the rise of the Internet of Things are driving an insatiable demand for wireless capacity. This demand requires networking and Internet infrastructures to evolve to meet the needs of current and future multimedia applications. Wireless HetNets will play an important role toward the goal of using a diverse spectrum to provide high quality-of-service, especially in indoor ...\",\n \"Title: MIMO-OFDM for a cellular deployment — Concepts, real-time implementation and measurements towards 3GPP-LTE\\nYear: 2007\\n\\nAbstract: In this paper we report on the system design and a realtime implementation of a MIMO-OFDM radio transmission system close to physical layer parameters as discussed in standardization for 3GPP-Long-Term-Evolution. We describe the implementation concept and first results on over-the-air transmission with a single user set-up occupying 20 MHz bandwidth and achieving more than 150 Mbit/s gross data rate in the 2×2 MIMO down-link and more than 50 Mbit/s in the single transmit antenna up-link. The demonstration system was only recently shown to the public at various trade shows like ITU in Hongkong and 3GSM in Barcelona.\",\n \"Title: Low-Latency Synchronization For Ofdm-Based Visible Light Communication\\nYear: 2015\\n\\nAbstract: 5G wireless systems are envisioned to provide ultra-high data rates, increased robustness and low latency for new applications such as machine-to-machine (M2M) and car-to-car (C2C) communications. This paper considers high-speed visible light communication (VLC) as a candidate serving technology to fulfill this set of requirements. Synchronization as the first step towards reliable data detection is studied here thoroughly aiming at high robustness and low complexity. Three schemes are reviewed, namely Schmidl-Cox and Park autocorrelation as well as a cross-correlation based approach, all using a predefined preamble. All schemes are examined concerning their robustness against multipath propagation and their precision in time estimation versus the preamble length. It is found that the simple Schmidl-Cox scheme, originally designed for complex-valued radio waveforms, can be applied also for real-valued optical wireless waveforms. Based on these investigations, an optimized preamble structure is finally proposed. Preamble boosting and fine synchronization can also be applied to reach a similar performance like optimal cross-correlation at reduced complexity. We study the fundamental trade-off between the preamble duration and the minimum signal-to-noise ratio (SNR) required for reliable synchronization and observe that ultra-low latency needs sufficient SNR.\",\n \"Title: On the impact of highpass filtering when using PAM-FDE for visible light communication\\nYear: 2016\\n\\nAbstract: A next generation optical wireless communications standard is currently established, denoted as IEEE 802.15.7r1, targeting data rates between 1 Mbit/s and 10 Gbit/s. Selecting an appropriate transmission scheme is one of the critical tasks. Following this issue, this paper gives a review on PAM-FDE in VLC. Based on PAM-FDE laboratory measurements, we demonstrate the need to include highpass filtering into the propagation model. In this paper, numerical analyses investigate the impact of the resulting baseline wander on the performance. We include a multi-level 5S6S coding technique in order to prepare PAM-FDE for practice. Finally, research topics are summarized.\",\n \"Title: A European view on the next generation optical wireless communication standard\\nYear: 2015\\n\\nAbstract: Optical wireless technology uses light for mobile communications. The idea is to simultaneously combine the illumination provided by modern high-power light-emitting diodes (LEDs) with high-speed wireless communications. There have been numerous practical demonstrations of this concept, and the technology is now well matured to be deployed in practice. Independent market analysts forecast a high-volume market for mobile communication devices connected to the ubiquitous lighting infrastructure. This paper aims to make optical and wireless industries aware of the requirement for standardization in this area. The authors present the view of the European COST 1101 research network OPTICWISE towards a next-generation optical wireless standard aiming at data rates from 1 Mbit/s to 10 Gbit/s. Besides key technical insights, relevant use cases and main features are described that were recently adopted by the IEEE 802.15.7r1 working group. Moreover, a channel model is introduced to enable assessment of technical proposals.\",\n \"Title: Software-defined Open Access for flexible and service-oriented 5G deployment\\nYear: 2016\\n\\nAbstract: The evolution of 5G mobile radio and its complex interaction with fixed access network infrastructures poses new challenges and opportunities. In this article, a software-defined converged fixed-mobile 5G architecture is introduced using carrier-grade Ethernet as a transport platform. An active remote node (ARN) is used to connect end-users. Powered at a radio base station, the ARN aggregates the traffic of fixed and mobile radio users. Transport capacity is reduced due to statistical multiplexing, and scalability is achieved by a modular design. The ARN enables software-defined networking (SDN) via the open-networks-as-a-service (Open NaaS) control and management plane. Adopting the Open Access model, this architecture offers both, multi-technology and multi-operator features. Next generation fronthaul, resource sharing, synchronization, low latency can all be established as services to build an advanced 5G infrastructure. Key concepts of the new architecture have been realized using low-cost hardware and offer economic high-speed, fixed and mobile Internet. E.g., for wireless connectivity to macro- and small cells, mm-wave links reaching 5 Gb/s and short-range optical wireless links have been used. As data rates can be scaled up, the proposed architecture is considered future-proof for converged 5G fixed-mobile access networks.\",\n \"Title: Hierarchical, virtualised and distributed intelligence 5G architecture for low-latency and secure applications.\\nYear: 2016\\n\\nAbstract: CHARISMA aims to tackle low-latency and end-to-end security for converged fixed/wireless 5G networks in order to meet the complex demands of emerging business paradigms, such as Smart Cities, eHealth and Industry 4.0. In this paper, we present the key drivers and requirements towards a hierarchical, distributed-intelligence 5G architecture, supporting low latency, security and open access as features intrinsic to its design. We also investigate the business perspective of the proposed 5G solution and the changes that can be foreseen for the telecom ecosystem. Copyright © 2016 John Wiley & Sons, Ltd.\",\n \"Title: The benefit of frequency-selective rate adaptation for optical wireless communications\\nYear: 2016\\n\\nAbstract: In this paper, we evaluate the potential of adaptive transmission for optical wireless communications, used together with a real-valued, DC-biased optical (DCO) orthogonal frequency-division multiplexing (OFDM) waveform. Particularly, we include frequency-selective bit- and power-loading on top of DCO-OFDM. This combination is well known as discrete multitone (DMT). We work out the significant advantage of frequency-selective rate adaptation for operation in both, low signal-to-noise ratios and non-line-of-sight scenarios, as compared to using a fixed modulation format commonly applied over all subcarriers and switching between these formats. Our evaluation is based on the channel impulse responses (CIRs) provided by the IEEE task group for the 802.15.7r1 standard. Transmission bandwidth is up to 200 MHz, as supported by modern optical wireless frontends.\",\n \"Title: Analog vs. next-generation digital fronthaul: How to minimize optical bandwidth utilization\\nYear: 2017\\n\\nAbstract: In this paper we investigate two promising approaches to reduce the optical bandwidth utilization in the mobile fronthaul of next-generation cloud radio access networks. We analyze and compare the performance of an analog radio-over-fiber and a new digital fronthaul in a chromatic dispersion-limited scenario. The former uses several analog channels, generated by up- and down-converting of baseband signals, and the latter utilizes simple OOK NRZ for the transmission to the remote radio head. Both principles are applied to a custom millimeter-wave system, consisting of several analog channels with baseband bandwidths as expected for 5G. The performance of both concepts at transmission rates of up to 100 Gb/s and 100 km of fiber is evaluated. We will show that both approaches are suitable for transmission distances typical for fronthaul and discuss their advantages and disadvantages. Furthermore, an optimized bandwidth concept for the analog radio-over-fiber system is presented, which enables transmission distances on the scale of metro networks.\",\n \"Title: Optical Wireless MIMO Experiments in an Industrial Environment.\\nYear: 2018\\n\\nAbstract: This paper reports on a field trial in a robotic manufacturing cell. Channel measurements and transmission experiments were conducted, assisting the development of a light-emitting diode-based optical wireless communication (OWC) system tailored for the needs of industrial wireless applications. These are moderate data rates, reliability, and low latency. Since dedicated radio spectrum is hardly a...\",\n \"Title: Digital-to-Analog Converters Using Frequency Interleaving: Mathematical Framework and Experimental Verification.\\nYear: 2018\\n\\nAbstract: The concept of frequency interleaving (FI) for digital-to-analog converters (DACs) has recently experienced renewed interest, in order to overcome the DACs’ bandwidth limitations. In this concept, the output signals of multiple DACs are interleaved in the frequency domain in order to generate a combined output signal that exceeds both the sampling rate and the bandwidth of a single DAC. In this paper, a mathematical framework for FI-DACs with a large number of DACs is presented and the inherent interdependencies between sampling rate, the number of samples, LO frequencies, symbol rate and analog frequency responses are highlighted. A mathematical expression for the distribution of data samples among the DACs is presented, taking into account bandwidth limitations of the analog components as well as guard bands to mitigate cross talk. In order to balance the FI-DAC’s parameters a mathematical optimization approach is introduced and illustrated with examples. Both simulation and experimental results validate the FI-DAC concept, and an outlook on implementation issues completes this paper.\",\n \"Title: A Converged Evolved Ethernet Fronthaul for the 5G Era.\\nYear: 2018\\n\\nAbstract: We assess the performance of two distinct functional splits based on latency/latency variation and mapping efficiency, both individually and in unison. By considering hardware-offloading possibilities for a low-layer split (especially a pre-resource mapper split) using an option-6 software-based local thermal equilibrium split as an example, we show how data rate, Ethernet frame size and, in gener...\",\n \"Title: Channel measurement campaigns for wireless industrial automation.\\nYear: 2019\\n\\nAbstract: The factories of the future will be highly digitalized in order to enable flexible and interconnected manufacturing processes. Especially wireless technologies will be beneficial for industrial automation. However, the high density of metallic objects is challenging for wireless systems due to multipath fading. In order to understand the signal propagation in industrial environments, this paper provides results from a number of channel measurement campaigns funded by the German research initiative \\\"Reliable wireless communication in the industry\\\". We give an overview of different measurement scenarios covering visible light communication and radio communication below 6 GHz. We analyze large and small scale parameters as well as delay statistics of the wireless channels. Finally, we discuss the importance of the results for the definition of industrial channel models.\",\n \"Title: High Speed 160 Gb/S Dmt Vcsel Transmission Using Pre-Equalization\\nYear: 2017\\n\\nAbstract: High speed single channel DMT operation of a directly modulated 850 nm VCSEL with 26 (31-1z bandwidth is presented. Successful transmission of 161. 152, 135 Gb/s over 10, 300, 550 m of 0M4 MMF is demonstrated at the SD-FEC FIER limit.\",\n \"Title: 100g Ofdm-Pon For Converged 5g Networks: From Concept To Real-Time Prototype\\nYear: 2017\\n\\nAbstract: We propose an implementation concept for a 100E OFDM-PON for a converged 5G network. A real-time OLT prototype and ONU detection with partial bandwidth are presented.\",\n \"Title: Long-Term Outdoor Measurements Using A Rate-Adaptive Hybrid Optical Wireless/60 Ghz Link Over 100 M\\nYear: 2017\\n\\nAbstract: In this paper, we evaluate the potential of a rate-adaptive hybrid link, combining LED based optical wireless and 60 GHz technologies. These links over short backhauling distances are well suited for the deployment of small radio cells in 5G mobile networks. Results from a 4.5-month outdoor field trial indicate that the availability for both links is 100%. The throughput of the LED-based optical link is higher in 90% of all cases while the 60 GHz link has a higher minimal throughput. If both links are aggregated, the hybrid link offers minimal/average/maximal data rates of 230/750/880 Mbps over 100 m in all weather conditions.\",\n \"Title: Ultra-Low Latency 5g Charisma Architecture For Secure Intelligent Transportation Verticals\\nYear: 2017\\n\\nAbstract: We describe low end-to-end latencies of 6.69 ms in the 5G CHARISMA network, that has been optimised for both device and system technologies speed, as well as with its virtualised, hierarchical and distributed, edge-centric architecture, that processes data as near as possible to their source and destination. Such an ultra-high speed 5G network can be utilised in intelligent transport system (ITS) applications, and we describe a public transport bus-based use case that takes advantage of the CHARISMA capabilities.\",\n \"Title: Bandwidth Extension Techniques For High-Speed Access Networks\\nYear: 2018\\n\\nAbstract: Recent advances in bandwidth extension techniques for high-speed access environments are presented together with own transmission experiments. Current issues and critical aspects are highlighted.\",\n \"Title: Next-Generation Optical Fronthaul In The Icirrus Project\\nYear: 2018\\n\\nAbstract: We discuss next-generation fronthaul solutions for 5G and legacy radio access networks. Architectures, findings and experimental results from recent lab and field trial activities are reported. (C) 2018 The Author(s).\",\n \"Title: Use Cases for Optical Wireless Communication\\nYear: 2018\\n\\nAbstract: We present results from trials in three promising uses cases for optical wireless communication (OWC): Mobile backhaul, industrial wireless, and indoor Li-Fi. We point out specific requirements and illustrate performance through measurements in typical scenarios.\",\n \"Title: Boosting 5G Through Ethernet: How Evolved Fronthaul Can Take Next-Generation Mobile to the Next Level\\nYear: 2018\\n\\nAbstract: Current approaches to the fronthaul for centralized, or cloud, radio access networks (C-RANs) need to be revised to meet the requirements of next-generation mobile networks. There are two major challenges. First, fronthaul signals need to be transported over public fixed-access networks, such as passive optical networks (PONs), typically sharing them with other services. Second, higher data rates ...\",\n \"Title: Bandwidth Enhancement For An Optical Access Link By Using A Frequency Interleaved Dac\\nYear: 2018\\n\\nAbstract: We present the experimental realization of the frequency interleaved DAC concept for an IM/DD based access link. The first open 80 GBd PAM-4 electrical eye diagram of the frequency-interleaved DAC without using post-equalization is presented.\",\n \"Title: Real-Time Optical Wireless Communication: Field-Trial in an Industrial Production Environment\\nYear: 2018\\n\\nAbstract: We present the first field-trial of a real-time optical wireless communication (OWC) system in an industrial manufacturing environment. Using spatial diversity schemes, we demonstrate how OWC can provide reliable low-latency communication despite the rapid movements of a production robot.\",\n \"Title: Behavioral Model for a High-Speed 2:1 Analog Multiplexer\\nYear: 2018\\n\\nAbstract: A novel concept for digital-to-analog converters (DACs) has been introduced recently, to overcome their bandwidth limitations by combining the outputs of multiple DACs with an analog multiplexer (AMUX). In this paper, a behavioral model for a high-speed 2: 1-AMUX is introduced, which significantly reduces the simulation time for a 2: 1-AMUX-DAC system. The behavioral model is implemented in Matlab and fitted with simulation data from an electronic design automation tool for a high-speed 2: 1-AMUX integrated circuit with a normalized mean square error < -20 dB. Eventually, multiple model parameters are varied in order to study their impact on the system's behavior.\",\n \"Title: Testbed Verification of New Fronthaul Technology for 5G Systems\\nYear: 2019\\n\\nAbstract: The fronthaul for 5th generation mobile systems (and beyond) has evolved with new splits for the radio access network functions defined, and the transport for these split interfaces having very different requirements. Testing of the transport for such split interfaces is reported, and it is shown that an Ethernet fronthaul transport network, which is capable of bringing efficiency gains through statistical multiplexing, can meet stringent latency and latency variation requirements, assuming buffering and playout of the radio waveforms and that timing/synchronization signals are prioritized. An aggregation technique for a 100 Gb/s Ethernet trunk which provides for such timing signals is demonstrated. Real-time monitoring of the Ethernet fronthaul for software-defined networking control and performance optimization is also shown.\",\n \"Title: Benefits of MIMO Mode Switching, Angular Diversity and Multiuser Multiplexing for LiFi\\nYear: 2021\\n\\nAbstract: We report on the first real-time experiments with distributed MIMO and multiple users for LiFi. MIMO mode switching and angular diversity are beneficial for robustness. Multiuser multiplexing helps in scenarios where users have complementary MIMO channels. (C) 2021 The Author(s)\",\n \"Title: ELIoT: New Features in LiFi for Next-Generation IoT\\nYear: 2021\\n\\nAbstract: The Internet of Things currently is predominantly narrowband and cannot always guarantee high reliability and low latency. Future IoT applications such as flexible manufacturing, augmented reality and self-driving vehicles need sophisticated real-time processing units in the cloud to which mobile IoT devices are connected. These high-capacity links meet the requirements of the upcoming 6G systems and cannot be facilitated by the current mobile communication infrastructure. Light communication, which is also denoted as LiFi, offers huge amounts of spectrum, extra security and interference-free transmission. We present the current state-of-the-art of LiFi systems and introduce new features needed for future IoT applications. We propose a distributed Multiple-Input Multiple-Output topology with a fronthaul using plastic optical fiber. Such a system offers seamless mobility between the light access points and also to 5G, besides low latency and integrated positioning. Future LiFi development, implementation and efforts towards standardization are addressed in the EU ELIoT project which is presented here.\",\n \"Title: Fiber-based Frequency Modulated LiDAR With MEMS Scanning Capability for Long-range Sensing in Automotive Applications\\nYear: 2021\\n\\nAbstract: Safe operation of driver assistance systems, especially at higher speeds, remains a challenge. For this automotive application, we propose a long-range coherent LiDAR system concept with two-dimensional micro electro-mechanical system (MEMS) scanning and sparse sensing capability. We address system design challenges for the transmitter, the fiber-based optics and coherent receiver, and the impact ...\",\n \"Title: All-Indoor Optical Customer Premises Equipment for Fixed Wireless Access\\nYear: 2021\\n\\nAbstract: We demonstrate an LED-based optical wireless link for fixed wireless access applications, at data rates of 1.5 Gbit/s over 50 m. Transmission between indoor equipment and outdoor access point is possible through metal-coated insulation glass.\",\n \"Title: Hy-Fi: Aggregation of LiFi and WiFi using MIMO in IEEE 802.11\\nYear: 2021\\n\\nAbstract: We present Hy-Fi, a system which combines light fidelity (LiFi) and radio based on the WiFi physical layer waveform by using the MIMO features available in IEEE 802.11-compliant commodity chip sets. Hy-Fi is based on two key ideas. First, we use inexpensive COTS hardware to facilitate direct transmission of WiFi waveforms over the optical wireless channel, as this is proposed in the IEEE P802.11bb...\",\n \"Title: LiFi based Positioning for Indoor Scenarios\\nYear: 2021\\n\\nAbstract: An indoor positioning system integrated with wireless communication is an essential tool for future Internet of Things applications. This paper presents a time-of-flight-based positioning approach based on networked optical wireless communication, which is also known as LiFi. Our proposed system is based on the ITU-T G.9991 standard and enables positioning besides communication using the existing ...\",\n \"Title: An Efficient Multi-Link Channel Model for LiFi\\nYear: 2021\\n\\nAbstract: In this paper, we report for the first time on a new channel modelling technique for multi-link LiFi scenarios. By considering simplified numerical calculation, it models the links between multiple optical frontends and multiple mobile devices much faster than previous approaches. For the first two diffuse reflections, we replace ray tracing method by frequency domain channel modelling technique. For the other higher order diffuse reflections, we use a well-established model based on the integrating sphere. For validation of our new approach, we performed distributed 4x2 MIMO channel measurements. Comparison of simulation and measurement yields a relative mean square error below 5 percent for the signals with a free line-of-sight. Our new technique enables efficient modeling of mobile scenarios and analyzing statistical properties of the LiFi channels.\",\n \"Title: Efficient Line Coding for Low-Power Optical Wireless Communications\\nYear: 2021\\n\\nAbstract: Optical wireless communications gains new interest in the recent years, due to high potential for use cases in the industrial internet of things. In order to address lower power consumption requirements at the mobile transmitter, an on-off-keying based physical layer has been developed by the IEEE task group 802.15.13, supporting a wide range of symbol rates from 12.5 to 200 MBaud. While providing robustness against high-pass filtering effects in analogue optical frontends, the currently used 8b10b line-coding causes a large overhead, notably limiting the achievable throughput. In this work, we investigate scrambler-based alternatives for the line-coding that reduce overhead at the cost of less-balanced signaling. We analyze statistical properties and thoroughly test the performance using a frontend-model derived from measurements on an optical frontend prototype. Accordingly, the 64b67b scheme is proposed as an optional line coding in the IEEE P802.15.13 project.\",\n \"Title: Analog 2:1 Multiplexer with over 110 GHz Bandwidth in SiGe BiCMOS Technology\\nYear: 2021\\n\\nAbstract: We report on a 2:1 analog multiplexer (AMUX) circuit in 130-nm SiGe BiCMOS technology. The technology offers HBTs with peak fT of 470 GHz and fmax of 650 GHz. S-parameter measurements of the AMUX IC show a significant leap in bandwidth compared to the circuit in the previous technology generation. The linear signal path offers a 3-dB-bandwith beyond 110 GHz, while the limitin...\",\n \"Title: LIDAR-Assisted Channel Modelling for LiFi in Realistic Indoor Scenarios\\nYear: 2022\\n\\nAbstract: We present a new, accurate, low complexity channel modelling methodology for LiFi in realistic indoor scenarios. A LIDAR scanner is used to capture the 3D environment in which the LiFi system is to be deployed. Next, the generated 3D point cloud data is pre-processed to determine the reflectance parameters of the walls and objects in the room. This is easier and more realistic than the manual definition of the environment, which is the current state of the art. As an additional innovation, the complexity of the channel modelling is reduced by: 1) modelling the line-of-sight and initial reflections precisely in the frequency-domain; 2) using a well-established analytical model based on the integrating sphere for all higher-order diffuse reflections. All steps together yield a substantially simplified channel modelling approach and model the links between multiple optical frontends and multiple mobile devices realistically. As a validation of our new approach, we compare measurements and simulations in two indoor scenarios: an empty room and a conference room with furniture. Simulations and measurements show excellent agreement with a mean square error below 3 percent. Moreover, we evaluate the performance of a distributed multiuser multiple-input multiple-output (MIMO) link and found excellent agreement between the model and measurements. Finally, we discuss the fundamental trade-off between complexity and model error, which depends on the scenario.\",\n \"Title: LIDAR-Assisted Channel Modelling for LiFi\\nYear: 2022\\n\\nAbstract: We present fast and accurate modelling of LiFi channels using data from LIDAR scans. Line-of-sight, first and residual reflections are modelled in the frequency-domain and using the integrating-sphere method. Model and measurement show good agreement. (C) 2022 The Author(s)\",\n \"Title: LiFi with 5G for the Smart Factory\\nYear: 2022\\n\\nAbstract: The ongoing shop floor digitalization confronts manufacturers with challenges in computer networks. Wi-Fi became a standard for enabling mobile applications in factories but suffers from operating in the shared industrial, scientific and medical (ISM) radio band, which makes Wi-Fi networks prone to interference from wireless networks that operate in parallel. Consequently, Wi-Fi is a less reliable wireless network technology for smart factories. LiFi and 5G are alternatives that do not rely on ISM bands. With a combination of 5G and LiFi we reach flexibility, reliability, wide coverage, and high throughput for fixed and mobile devices in factories. In this paper, we demonstrate the use of LiFi as a non-3GPP access technology for the 5G core network and describe our initial testing of the N3IWF implementation. Besides, this paper describes a multistage demonstrator set-up, which allows to conduct initial validation tests in a distributed testbed environment. This approach enables the direct migration of developed system components into a real factory environment considering the rough environment of manufacturing halls.\",\n \"Title: An Energy-Efficient Optical Wireless OFDMA Scheme for Medical Body-Area Networks\\nYear: 2022\\n\\nAbstract: The transfer of health monitoring data from multiple patients using wireless body-area networks requires the use of robust, and energy and bandwidth efficient multiple-access schemes. This paper considers the frequency-division multiple access for the wireless uplink to a fixed access point when using infrared signals to collect medical data from several patients inside an emergency waiting room. The conventional optical orthogonal scheme applies Hermitian symmetry to obtain real-valued signals, which implies increased computational complexity. We consider a new approach transmitting only the real part of a complex-valued signal, where no such constraint is imposed. Based on the proposed scheme, and taking into account the limited dynamic range of an infrared light-emitting diode, we study the performance of direct current biased and asymmetrically clipped schemes, and show their advantage in terms of energy efficiency and computational complexity, as compared with the conventional schemes. For instance, we show that by using asymmetric clipping, around 35mW less transmit power is needed to achieve a bit error rate of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\mathrm {10}^{-3}$ </tex-math></inline-formula>\\n in the considered scenario. We also demonstrate the robustness of the proposed scheme against multiple access interference.\",\n \"Title: Techno-Economics of LiFi in IoT Applications\\nYear: 2022\\n\\nAbstract: This paper describes the first techno-economical study for the deployment of very dense wireless networks for new Internet of things (IoT) applications. We propose mobile optical wireless communication (OWC) also known as light fidelity (LiFi) because it offers unique advantages for the IoT such as robustness through exclusive channel access in the unlicensed optical spectrum, lower latency, and enhanced security. We investigate the deployment of LiFi in an industrial scenario, as currently specified by ITU-T recommendation G.9991, including the required fixed backbone and assuming full coverage. We propose six different LiFi topologies and compare them in different industrial scenarios. The comparison is performed in terms of Bill of Material, and in terms of costs. We show that a fully wired topology requires higher installation costs but incurs in lower operational costs, resulting in lower total costs of ownership (TCO) than other wireless topologies. Furthermore, power consumption has been identified as the cost driver for all topologies (more than 200% of the initial investments), triggering the need for power-saving techniques. Last but not least, the separation of Optical Front Ends (OFEs) has been identified as a critical design parameter, as shorter separation requires higher costs but reduces the cost per delivered bitrate. We discuss promising ways for the deployment of very dense wireless networks as key to bringing LiFi into future IoT applications.\",\n \"Title: Simultaneous Channel Estimation for Pulsed-Modulation Optical Wireless Communications\\nYear: 2022\\n\\nAbstract: In this paper, suitable estimation sequences and algorithms for the simultaneous channel estimation in an optical wireless communication system are assessed. We focus on a multi-user-MISO setup and an on-off-keying based pulsed-modulation physical layer. The performance of the tested configurations is evaluated using simulations under the constraints of imperfect time synchronization between the transmitters and band-pass distortions. Furthermore, a new family of binary channel estimation sequences, named Variable Sampling Factor (VSF) sequences, is proposed with the goal of enabling simultaneous estimation even between terminals using different sample clock rates. Despite a high variance of channel gains in the used model, the best presented algorithm is able to detect 6 out of 8 transmitters on average.\",\n \"Title: All-Optical Distributed MIMO for LiFi: Spatial Diversity Versus Spatial Multiplexing\\nYear: 2022\\n\\nAbstract: LiFi or networked optical wireless communication is likely to play an important role in offloading mobile data traffic from radio into the optical spectrum. As the number of Internet of Things (IoT) devices is growing, the RF spectrum becomes a rare resource. Imaging IoT sensors like cameras, ultrasonic devices, and Lidars have real-time requirements, need a high-capacity uplink, and operate in environments that cause or are sensitive against electromagnetic interference. In this paper, for the first time, we present realtime communication over an all-optical fixed-wireless LiFi link based on the distributed multiple-input multiple-output concept. For distributing the wireless signals, plastic optical fibers are used as an analog front-haul. We study the operation of the distributed multiple-input multiple-output link in two modes, i.e., spatial diversity and spatial multiplexing. For the diversity mode, a new combiner is presented, which can support equal gain as well as selection combining. We demonstrate that selection combining is highly effective and enables a similar LiFi performance in up- and downlink, as it is desirable for industrial applications. For the spatial multiplexing mode, we observe that the channel rank and the achievable throughput depend strongly on the user location. As effective solutions, we study the benefits of angular diversity and multiple-input multiple-output mode switching together with multi-user multiplexing and conclude that a dynamic switching between spatial diversity and spatial multiplexing is a practical approach.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":84,"string":"84"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":46,"string":"46"}}},{"rowIdx":47,"cells":{"question_id":{"kind":"string","value":"Min Chun Hu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Semantic Based Background Music Recommendation for Home Videos\" using the following items: background music, recommendation scheme, short-term motion, tempo distribution, semantics"},"answer":{"kind":"string","value":"In this paper, we propose a new background music recommendation scheme for home videos and two new features describing the short-term motion/tempo distribution in visual/aural content. Unlike previous researches that merely matched the visual and aural contents through a perceptual way, we incorporate the textual semantics and content semantics while determining the matching degree of a video and a song. The key idea is that the recommended music should contain semantics that relate to the ones in the input video and that the rhythm of the music and the visual motion of the video should be harmonious enough. As a result, a few user-given tags and automatically annotated tags are used to compute their relation to the lyrics of the songs for selecting candidate musics. Then, we use the proposed motion-direction histogram (MDH) and pitch tempo pattern (PTP) to do the second-run selection. The user preference to the music genre is also taken into account as a filtering mechanism at the beginning. The primitive user evaluation shows that the proposed scheme is promising."},"correct_answer":{"kind":"string","value":"In this paper, we propose a new background music recommendation scheme for home videos and two new features describing the short-term motion/tempo distribution in visual/aural content. Unlike previous researches that merely matched the visual and aural contents through a perceptual way, we incorporate the textual semantics and content semantics while determining the matching degree of a video and a song. The key idea is that the recommended music should contain semantics that relate to the ones in the input video and that the rhythm of the music and the visual motion of the video should be harmonious enough. As a result, a few user-given tags and automatically annotated tags are used to compute their relation to the lyrics of the songs for selecting candidate musics. Then, we use the proposed motion-direction histogram (MDH) and pitch tempo pattern (PTP) to do the second-run selection. The user preference to the music genre is also taken into account as a filtering mechanism at the beginning. The primitive user evaluation shows that the proposed scheme is promising."},"documents":{"kind":"list like","value":["Title: Tennis Real Play\nYear: 2012\n\nAbstract: Tennis Real Play (TRP) is an interactive tennis game system constructed with models extracted from videos of real matches. The key techniques proposed for TRP include player modeling and video-based player/court rendering. For player model creation, we propose the process for database normalization and the behavioral transition model of tennis players, which might be a good alternative for motion capture in the conventional video games. For player/court rendering, we propose the framework for rendering vivid game characters and providing the real-time ability. We can say that image-based rendering leads to a more interactive and realistic rendering. Experiments show that video games with vivid viewing effects and characteristic players can be generated from match videos without much user intervention. Because the player model can adequately record the ability and condition of a player in the real world, it can then be used to roughly predict the results of real tennis matches in the next days. The results of a user study reveal that subjects like the increased interaction, immersive experience, and enjoyment from playing TRP.","Title: TravelBuddy: Interactive Travel Route Recommendation with a Visual Scene Interface\nYear: 2014\n\nAbstract: In this work, we propose a convenient system for trip planning and aim to change the behavior of trip planners from exhaustively searching information to receiving useful travel recommendations. Given the essential and optional user inputs, our system automatically recommends a route that suits the traveler based on a real-time route planning algorithm and allows the user to make adjustment according to their preferences. We construct a traveling database by collecting photos taken around famous attractions and analyzing these photos to extract each attraction's travel information including popularity, typical stay time, available visiting time in a day, and visual scenes of different time. All the extracted travel information are presented to the user to help him/her efficiently know more about different attractions so that he/she can modify the inputs to obtain a more favorable travel route. The experimental results show that our system can effectively help the user to plan the journey.","Title: Efficient human detection in crowded environment based on motion and appearance information\nYear: 2013\n\nAbstract: Detecting human in crowded environment is profitable but challenging in video surveillance. We propose an efficient human detection method by combining both motion and appearance clues. Moving pixels are first extracted by background subtraction, and then a filtering step is used to narrow the range for human template matching. We utilize integral images to fast generate shape information from edge maps of each frame and define the matching probability to be capable of detecting both full-body and partial-body. Representative human templates are constructed by sparse contours on the basis of the point distribution model (PDM). Moreover, linear regression analysis is also applied to adaptively adjust the template sizes. With the aid of the proposed foreground ratio filtering and the multi-sized template matching techniques, our method not only can efficiently detect human in a crowded environment but also largely enhance the detection accuracy.","Title: Actions speak louder than words: searching human action video based on body movement\nYear: 2012\n\nAbstract: Human action video search is a frequent demand in multimedia applications, and conventional video search schemes based on keywords usually fail to correctly find relevant videos due to noisy video tags. Observing the widespread use of Kinect-like depth cameras, we propose to search human action videos by directly performing the target action with body movements. Human actions are captured by Kinect and the recorded depth information is utilized to measure the similarity between the query action and each human action video in the database. We use representative depth descriptors without learning optimization to achieve real-time and promising performance as compatible as those of the leading methods based on color images and videos. Meanwhile, a large Depth-included Human Action video dataset, namely DHA, is collected to prove the effectiveness of the proposed video search system.","Title: Who's the Best Charades Player? Mining Iconic Movement of Semantic Concepts\nYear: 2014\n\nAbstract: Charades is a guessing game with the idea for one player to act out a semantic concept (i.e. a word or phrase) for the other players to guess. An observation from playing charades is that people's cognition on the iconic movements associated with a semantic concept would be often inconsistent, and this fact has long been ignored in the multimedia research. Therefore, the novelty of this work is to propose an automation for mining the most representative videos for each semantic concept as its iconic movements from a large set of related videos containing various human actions. The discovered iconic movements can be further employed to benefit a broad range of tasks, such as human action recognition and retrieval. For our purpose, a new video benchmark is also presented and the experiments demonstrated our approach potential to human action based applications.","Title: Learning and Recognition of On-Premise Signs From Weakly Labeled Street View Images\nYear: 2014\n\nAbstract: Camera-enabled mobile devices are commonly used as interaction platforms for linking the user's virtual and physical worlds in numerous research and commercial applications, such as serving an augmented reality interface for mobile information retrieval. The various application scenarios give rise to a key technique of daily life visual object recognition. On-premise signs (OPSs), a popular form of commercial advertising, are widely used in our living life. The OPSs often exhibit great visual diversity (e.g., appearing in arbitrary size), accompanied with complex environmental conditions (e.g., foreground and background clutter). Observing that such real-world characteristics are lacking in most of the existing image data sets, in this paper, we first proposed an OPS data set, namely OPS-62, in which totally 4649 OPS images of 62 different businesses are collected from Google's Street View. Further, for addressing the problem of real-world OPS learning and recognition, we developed a probabilistic framework based on the distributional clustering, in which we proposed to exploit the distributional information of each visual feature (the distribution of its associated OPS labels) as a reliable selection criterion for building discriminative OPS models. Experiments on the OPS-62 data set demonstrated the outperformance of our approach over the state-of-the-art probabilistic latent semantic analysis models for more accurate recognitions and less false alarms, with a significant 151.28% relative improvement in the average recognition rate. Meanwhile, our approach is simple, linear, and can be executed in a parallel fashion, making it practical and scalable for large-scale multimedia applications.","Title: Gait-based action recognition via accelerated minimum incremental coding length classifier\nYear: 2012\n\nAbstract: In this paper, we present a novel human action recognition approach based on gait energy image (GEI) and minimum incremental coding length (MICL) classifier. GEIs are extracted from video clips and transformed into vectors as input features, and MICL is employed to classify each GEI. We also use multiple cameras to capture GEIs of different views, and the voting strategy is applied after the MICL classification results to improve the overall system performance. Experimental results show that the proposed approach can achieve approximately 95% of accuracy. For practical usage, we also speed up the classification time so that it can be accomplished in a very short time. Moreover, other classification methods are used to classify GEIs and the experimental result shows that MICL is the most suitable classifier for this approach. Besides our recorded action clips, the Weizmann dataset is also used to verify the capability of our approach. The experimental results show that our approach is competitive to other state-of-the-art action recognition methods.","Title: Robust Camera Calibration and Player Tracking in Broadcast Basketball Video\nYear: 2011\n\nAbstract: With the growth of fandom population, a considerable amount of broadcast sports videos have been recorded, and a lot of research has focused on automatically detecting semantic events in the recorded video to develop an efficient video browsing tool for a general viewer. However, a professional sportsman or coach wonders about high level semantics in a different perspective, such as the offensive or defensive strategy performed by the players. Analyzing tactics is much more challenging in a broadcast basketball video than in other kinds of sports videos due to its complicated scenes and varied camera movements. In this paper, by developing a quadrangle candidate generation algorithm and refining the model fitting score, we ameliorate the court-based camera calibration technique to be applicable to broadcast basketball videos. Player trajectories are extracted from the video by a CamShift-based tracking method and mapped to the real-world court coordinates according to the calibrated results. The player position/trajectory information in the court coordinates can be further analyzed for professional-oriented applications such as detecting wide open event, retrieving target video clips based on trajectories, and inferring implicit/explicit tactics. Experimental results show the robustness of the proposed calibration and tracking algorithms, and three practicable applications are introduced to address the applicability of our system.","Title: Human action recognition and retrieval using sole depth information\nYear: 2012\n\nAbstract: Observing the widespread use of Kinect-like depth cameras, in this work, we investigate into the problem of using sole depth data for human action recognition and retrieval in videos. We proposed the use of simple depth descriptors without learning optimization to achieve promising performances as compatible to those of the leading methods based on color images and videos, and can be effectively applied for real-time applications. Because of the infrared nature of depth cameras, the proposed approach will be especially useful under poor lighting conditions, e.g. the surveillance environments without sufficient lighting. Meanwhile, we proposed a large Depth-included Human Action video dataset, namely DHA, which contains 357 videos of performed human actions belonging to 17 categories. To the best of our knowledge, the DHA is one of the largest depth-included video datasets of human actions.","Title: Interactive digital scrapbook generation for travel photos based on design principles of typography\nYear: 2011\n\nAbstract: To facilitate the photo management and sharing tasks, many application tools have been developed to generate pleasant photo slideshows, collages, or scrapbooks by applying simple templates/layouts and visual effects. In this work, we propose a convenient digital scrapbook generating system for travel photos, named as IS-Scrapbook, which keeps the virtues while dismisses the drawbacks of conventional digital photo presentation styles. The IS-Scrapbook system has three friendly attributes compared to other photo presentation tools. First, aiming to attract the audience, we highlight objects more meaningful or familiar to the viewer, e.g. the landmark and the protagonist in the photos. Second, five basic design principles of typography, i.e. proximity, contrast, balance, color harmony and repetition, are applied to produce more vivacious layouts. Third, the system automatically generates a digital scrapbook with a default layout, and the user can further adjust photo positions and enrich each page by sketching or inserting dialog bubbles with the aid of the developed user interface. User study shows that the proposed work enhances the experiences of photo browsing and gives a brand-new way of photo sharing.","Title: Traveling through space-time: an interactive photo browsing system\nYear: 2012\n\nAbstract: Digital photos are estimated to be generated and uploaded to social image websites (e.g. Flickr) in the amount of 375 petabytes annually [Tueld et al.], and plenty of these photos are annotated with the creation time/date in EXIF information. Among these photos, a large number of images are geo-tagged (e.g. GPS and landmark names) to indicate where the photo was taken. Moreover, several public databases composed of pictures captured by live cameras at various locations are available on the internet. Therefore, it has become a crucial task to enable an intuitive and efficient way for users to browse large-scale photos in space and time.","Title: Action tutor: real-time exemplar-based sequential movement assessment with kinect sensor\nYear: 2012\n\nAbstract: With the aid of depth camera, such as Microsoft Kinect, the difficulty of vision-based posture estimation is greatly decreased, and human action analysis has achieved a wide range of applications. However, there is still much to do to develop effective movement assessment technique, which bridges the results of human posture estimation and the understanding of human action performance. In this work, we propose an action tutor system which enables the user to interactively retrieve the learning exemplar of the target action movement and to immediately acquire motion instructions while learning it in front of the Kinect. In the retrieval stage, non-linear time warping algorithms are designed to retrieve video segments similar to the query movement roughly performed by the user. In the learning stage, the user learns according to the selected video exemplar, and the motion assessment including both static and dynamic differences is presented to the user in a more effective and organized way, helping him/her to perform the action movement correctly.","Title: Rectangling Stereographic Projection for Wide-Angle Image Visualization\nYear: 2013\n\nAbstract: This paper proposes a new projection model for mapping a hemisphere to a plane. Such a model can be useful for viewing wide-angle images. Our model consists of two steps. In the first step, the hemisphere is projected onto a swung surface constructed by a circular profile and a rounded rectangular trajectory. The second step maps the projected image on the swung surface onto the image plane through the perspective projection. We also propose a method for automatically determining proper parameters for the projection model based on image content. The proposed model has several advantages. It is simple, efficient and easy to control. Most importantly, it makes a better compromise between distortion minimization and line preserving than popular projection models, such as stereographic and Pannini projections. Experiments and analysis demonstrate the effectiveness of our model.","Title: Efficient human detection in crowded environment\nYear: 2015\n\nAbstract: Detecting humans in crowded environment is profitable but challenging in video surveillance. We propose an efficient human detection method by combining both motion and appearance clues. Moving pixels are first extracted by background subtraction, and then a filtering step is used to narrow the range for human template matching. We utilize integral images to fast generate shape information from edge maps of each frame and define the matching probability to be capable of detecting both full-body and partial-body. Representative human templates are constructed by sparse contours on the basis of the point distribution model. Moreover, linear regression analysis is also applied to adaptively adjust the template sizes. With the aid of the proposed foreground ratio filtering and the multi-sized template matching techniques, experimental results show that our method not only can efficiently detect humans in a crowded environment, but also largely enhance the resultant detection accuracy.","Title: Real-time human movement retrieval and assessment with Kinect sensor.\nYear: 2015\n\nAbstract: The difficulty of vision-based posture estimation is greatly decreased with the aid of commercial depth camera, such as Microsoft Kinect. However, there is still much to do to bridge the results of human posture estimation and the understanding of human movements. Human movement assessment is an important technique for exercise learning in the field of healthcare. In this paper, we propose an action tutor system which enables the user to interactively retrieve a learning exemplar of the target action movement and to immediately acquire motion instructions while learning it in front of the Kinect. The proposed system is composed of two stages. In the retrieval stage, nonlinear time warping algorithms are designed to retrieve video segments similar to the query movement roughly performed by the user. In the learning stage, the user learns according to the selected video exemplar, and the motion assessment including both static and dynamic differences is presented to the user in a more effective and organized way, helping him/her to perform the action movement correctly. The experiments are conducted on the videos of ten action types, and the results show that the proposed human action descriptor is representative for action video retrieval and the tutor system can effectively help the user while learning action movements.","Title: Eat as much as you can: a kinect-based facial rehabilitation game based on mouth and tongue movements\nYear: 2014\n\nAbstract: In this demo, we present a Kinect-based interactive game which provides patients of facial palsy with a better and more fun way to perform facial physical therapy. By letting the user get scores when he/she bites or licks the virtual foods falling from the sky, the game goads the user into exercising their facial muscles. A robust bite action detector and an efficient tip-of-tongue locating method are developed to realize this game. Based on the head pose estimated by the depth clue, we classify the face orientation and locate the mouth region in each frame. The movements of lips are measured to detect the bite action, and different strategies are designed to more accurately detect the tip-of-tongue for various face orientations. The experimental results show that our method can be successfully applied to different users.","Title: Efficient QR Code Beautification with High Quality Visual Content\nYear: 2015\n\nAbstract: QR code is generally used for embedding messages such that people can conveniently use mobile devices to capture the QR code and acquire information through a QR code reader. In the past, the design of QR code generators only aimed to achieve high decodability and the produced QR codes usually look like random black-and-white patterns without visual semantics. In recent years, researchers have been tried to endow the QR code with aesthetic elements and QR code beautification has been formulated as an optimization problem that minimizes the visual perception distortion subject to acceptable decoding rate. However, the visual quality of the QR code generated by existing methods still leaves much to be desired. In this work, we propose a two-stage approach to generate QR code with high quality visual content. In the first stage, a baseline QR code with reliable decodability but poor visual quality is first synthesized based on the Gauss-Jordan elimination procedure. In the second stage, a rendering mechanism is designed to improve the visual quality while avoid affecting the decodability of the QR code. The experimental results show that the proposed method substantially enhances the appearance of the QR code and the processing complexity is near real-time.","Title: Multimedia home environment streaming system design\nYear: 2013\n\nAbstract: The consumer electronic devices become more popular, especially in the multimedia home environment. This paper presents a real-time scalable streaming system in home environment. The system is designed with a bandwidth adaptive control. In the implementation system, the server provides smooth SVC streaming for users with heterogeneous network environment. To again bandwidth fluctuation, the frame rate is adaptive according to bit rates with bandwidth condition. The scheme is implemented in the system with real streaming sequence test bench, the peak signal noise ratio (PSNR) improves in average 6.23% than the original JSVM software. Therefore, users have a smoothly video service during transmission in multimedia home environment.","Title: Photo sundial: Estimating the time of capture in consumer photos.\nYear: 2016\n\nAbstract: The time of capture of consumer photos provides rich information in temporal context and has been widely employed for solving various multimedia problems, such as multimedia retrieval and social media analysis. However, we observed that the recorded time stamp in a consumer photo does not often correspond to the true local time at which the photo was taken. This would greatly damage the robustness of time-aware multimedia applications, such as travel route recommendation. Therefore, motivated by the use of traditional sundials, this work proposes a system, Photo Sundial, for estimating the time of capture by exploiting the astronomical theory. In particular, we infer the time by establishing its relations to the measurable astronomical factors from a given outdoor photo, i.e. the sun position in the sky and the camera viewing direction in the photo-taken location. In practice, since it is more often that people would take multiple photos in a single trip, we further develop an optimization framework to jointly estimate the time from multiple photos. Experimental results show that the average estimated time error is less than 0.9h by the proposed approach, with a significant 65% relative improvement compared to the state-of-the-art method (2.5h). To the best of our knowledge, this work is the first study in multimedia research to explicitly address the problem of time of capture estimation in consumer photos, and the achieved performances highly encourage our system for practical applications.","Title: Color Correction Parameter Estimation on the Smartphone and Its Application to Automatic Tongue Diagnosis.\nYear: 2016\n\nAbstract: An automatic tongue diagnosis framework is proposed to analyze tongue images taken by smartphones. Different from conventional tongue diagnosis systems, our input tongue images are usually in low resolution and taken under unknown lighting conditions. Consequently, existing tongue diagnosis methods cannot be directly applied to give accurate results.We use the SVM (support vector machine) to predict the lighting condition and the corresponding color correction matrix according to the color difference of images taken with and without flash. We also modify the state-of-the-art work of fur and fissure detection for tongue images by taking hue information into consideration and adding a denoising step.Our method is able to correct the color of tongue images under different lighting conditions (e.g. fluorescent, incandescent, and halogen illuminant) and provide a better accuracy in tongue features detection with less processing complexity than the prior work.In this work, we proposed an automatic tongue diagnosis framework which can be applied to smartphones. Unlike the prior work which can only work in a controlled environment, our system can adapt to different lighting conditions by employing a novel color correction parameter estimation scheme.","Title: B-box Mixer: An Interactive UI for Generating B-box Music\nYear: 2015\n\nAbstract: B-box is a form of vocal percussion that imitates rhythms in various types of sound, especially musical instruments. As b-box becoming popular, more and more people want to learn b-box and make their own b-box music. However, not everyone has the talent for generating harmonic b-box music. In this work, we develop an interactive system which helps the user easily compose b-box music given two inputs: an unaccompanied vocal song and a piece of b-box rhythm. The audio signals of the two inputs are analyzed and adaptively matched on the basis of their beats. The state of the art beat detection technique does not perform well on vocal songs. Hence, we propose to partition the song into short segments and estimate the average tempo for each segment so that the adjustment of tempo will not be affected too much by the wrongly detected beats. With the proposed system, people who love b-box or are not familiar with b-box can enjoy producing their own b-box music.","Title: Locality Constrained Sparse Representation for Cat Recognition.\nYear: 2016\n\nAbstract: Cat (Felis catus) plays an important social role within our society and can provide considerable emotional support for their owners. Missing, swapping, theft, and false insurance claims of cat have become global problem throughout the world. Reliable cat identification is thus an essential factor in the effective management of the owned cat population. The traditional cat identification methods by permanent (e.g., tattoos, microchip, ear tips/notches, and freeze branding), semi-permanent (e.g., identification collars and ear tags), or temporary (e.g., paint/dye and radio transmitters) procedures are not robust to provide adequate level of security. Moreover, these methods might have adverse effects on the cats. Though the work on animal identification based on their phenotype appearance (face and coat patterns) has received much attention in recent years, however none of them specifically targets cat. In this paper, we therefore propose a novel biometrics method to recognize cat by exploiting their noses that are believed to be a unique identifier by cat professionals. As the pioneer of this research topic, we first collect a Cat Database that contains 700 cat nose images from 70 different cats. Based on this dataset, we design a representative dictionary with data locality constraint for cat identification. Experimental results well demonstrate the effectiveness of the proposed method compared to several state-of-the-art feature-based algorithms.","Title: Representative photo selection for restaurants in food blogs\nYear: 2015\n\nAbstract: Nowadays, people write comments of restaurants and upload related photos to food blogs after visiting there. Developing a mobile application which enables the user to effectively search restaurants from data in these blogs becomes an emerging need. Besides reading the comments, most people will give a glance at food photos of a restaurant and then decide whether to go or what to eat. Therefore, we propose a system to analyze and select representative photos for each restaurant based on blog-platform media. A strong food detection model is trained to retrieve food photos and an aesthetic quality assessment method is utilized to select representative photos. Based on these representative photos, users can more easily have the impression of the restaurant and review the blog in an organized way. The experimental results show that our system can generate better representative photos (i.e. much closer to the users' preferences) than existing blog platforms.","Title: VRank: Voting system on Ranking model for human age estimation\nYear: 2015\n\nAbstract: Ranking algorithms have proven the potential for human age estimation. Currently, a common paradigm is to compare the input face with reference faces of known age to generate a ranking relation whereby the first-rank reference is exploited for labeling the input face. In this paper, we proposed a framework to improve upon the typical ranking model, called Voting system on Ranking model (VRank), by leveraging relational information (comparative relations, i.e. if the input face is younger or older than each of the references) to make a more robust estimation. Our approach has several advantages: firstly, comparative relations can be explicitly involved to benefit the estimation task; secondly, few incorrect comparisons will not influence much the accuracy of the result, making this approach more robust than the conventional approach; finally, we propose to incorporate the deep learning architecture for training, which extracts robust facial features for increasing the effectiveness of classification. In comparison to the best results from the state-of-the-art methods, the VRank showed a significant outperformance on all the benchmarks, with a relative improvement of 5.74% ~ 69.45% (FG-NET), 19.09% ~ 68.71% (MORPH), and 0.55% ~ 17.73% (IoG).","Title: Real-Time Sign Language Recognition in Complex Background Scene Based on a Hierarchical Clustering Classification Method\nYear: 2016\n\nAbstract: Cameras are embedded in many mobile/wearable devices and can be used for gesture recognition or even sign language recognition to help the deaf people communicate with others. In this paper, we proposed a vision-based gesture recognition system which can be used in environments with complex background. We design a method to adaptively update the skin color model for different users and various lighting conditions. Three kinds of features are combined to describe the contours and the salient points of hand gestures. Principle Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Support Vector Machine (SVM) are integrated to construct a novel hierarchical classification scheme. We evaluated the proposed recognition method on two datasets: (1) the CSL dataset collected by ourselves, in which images were captured in complex background. (2) The public ASL dataset, in which images of the same gesture were captured in different lighting conditions. Our method achieves the accuracies of 99.8% and 94%, respectively, which outperforms the existing works.","Title: A Framework of Enlarging Face Datasets Used for Makeup Face Analysis\nYear: 2016\n\nAbstract: There have been lots of research about face detection and face recognition. However, faces with makeup usually seriously affect the face recognition result. If we want to recognize the face with higher accuracy, it would be better to first know whether the input face is with makeup or not, and we can use corresponding makeup face or non-makeup face model to recognize it. Unfortunately, the current available datasets for face analysis do not include enough makeup and non-makeup image pairs of users. In this work, we propose a framework to efficiently increase pairs of makeup and non-makeup face images for the existing makeup face datasets. Patch-based features are extracted and support vector machine (SVM) is applied to classify whether a face image is with makeup. The technique of partial least squares (PLS) is then employed to authenticate whether a makeup photo and a non-makeup photo belong to the same person. By combining the makeup detection and the face authentication methods, we can successfully construct a larger face dataset that can be specifically used for applications of makeup face analysis.","Title: Immersive virtual reality with multimodal interaction and streaming technology.\nYear: 2016\n\nAbstract: In this demo, we present an immersive virtual reality (VR) system which integrates multimodal interaction sensors (i.e., smartphone, Kinect v2, and Myo armband) and streaming technology to improve the VR experience. The integrated system solves the common problems in most VR systems: (1) the very limited playing area due to transmission cable between computer and display/interaction devices, and (2) non-intuitive way of controlling virtual objects. We use Unreal Engine 4 to develop an immersive VR game with 6 interactive levels to demonstrate the feasibility of our system. In the game, the user not only can freely walk within a large playing area surrounded by multiple Kinect sensors but also select the virtual objects to grab and throw with the Myo armband. The experiment shows that our idea is workable for VR experience.","Title: A Sensor-Based Official Basketball Referee Signals Recognition System Using Deep Belief Networks.\nYear: 2017\n\nAbstract: In a basketball game, basketball referees who have the responsibility to enforce the rules and maintain the order of the basketball game has only a brief moment to determine if an infraction has occurred, later they communicate with the scoring table using hand signals. In this paper, we propose a novel system which can not only recognize the basketball referees' signals but also communicate with the scoring table in real-time. Deep belief network and time-domain feature are utilized to analyze two heterogeneous signals, surface electromyography (sEMG) and three-axis accelerometer (ACC) to recognize dynamic gestures. Our recognition method is evaluated by a dataset of 9 various official hand signals performed by 11 subjects. Our recognition model achieves acceptable accuracy rate, which is 97.9% and 90.5% for 5-fold Cross Validation (5-foldCV) and Leave-One-Participant-Out Cross Validation (LOPOCV) experiments, respectively. The accuracy of LOPOCV experiment can be further improved to 94.3% by applying user calibration.","Title: Tongue Fur Detection On The Smartphone\nYear: 2016\n\nAbstract: Tongue fur is an important objective basis for clinical diagnosis and treatment in western medicine and tongue diagnosis for Chinese medicine. Given the high penetration and built-in sensors of smartphones, and the need for continuous monitoring of health conditions, we propose an automatic tongue diagnosis framework on smartphone. However, tongue images taken by smartphone are quite different in color due to various lighting conditions, so we have to solve this problem to detect the correct tongue furs. In previous work mentioned that their tongue diagnosis systems are set up in a constrained well-controlled environment (e.g. with fixed lighting condition), but we purpose to let users make tongue diagnosis with their own smartphones no matter where they are. Therefore, we provide a way to detect tongue furs under different lighting conditions (e.g. fluorescent, halogen, and incandescent illuminant) by the com bination of series methods: 1. Lighting condition estimation, 2. Tongue image color correction 3. Tongue fur (white fur) detection. We use the SVM to estimate the lighting condition and do the color correction with the corresponding correction matrix for current lighting condition. After getting the corrected tongue images, we use the detection model training by SVM to detect the white fur region in corrected tongue images. In this thesis, we propose a lighting condition estimation method according to color difference of tongue images taken with and without flash on the smartphone under different lighting condition; we also verify that it need to search corresponding parameter of correction matrix for color correction depend on different lighting condition; finally, we observe that the overlap rate of corrected tongue images for Hal. and Inc. lighting has been clearly upgraded with our correction parameter and the white fur can be identify if the overlap rate of corrected tongue images exceed 60%.","Title: Recognition of Easily-confused TCM Herbs Using Deep Learning.\nYear: 2017\n\nAbstract: Chinese herbal medicine (CHM) plays an important role of treatment in traditional Chinese medicine (TCM). Traditionally, CHM is used to restore the balance of the body for sick people and maintain health for common people. However, lack of the knowledge of the herbs may cause misuse of the herbs. In this demo, we will present a real-time smartphone application, which can not only recognize easily-confused herb based on Convolutional Neural Network (CNN), but also provide relevant information about the detected herbs. Our Chinese herb recognition system is implemented on a cloud server and can be used by the client user via smartphone. The recognition system is evaluated by 5-fold cross validation method and the accuracy is around 96%, which is adequate for real-world use.","Title: Localization of Acupoints using Augmented Reality.\nYear: 2017\n\nAbstract: An augmented reality (AR) system for acupuncture points localization is implemented on an Android smartphone. The user can utilize such a system to locate the relevant acupuncture point for the purpose of symptom relief (e.g. through acupressure).","Title: DeepSheet: A sheet music generator based on deep learning\nYear: 2017\n\nAbstract: Sheet music has long been regarded as one of the most effective medias for musicians, music players, and amateurs to communicate with each other. It is also an intuitive way for non-professionals to learn how to play a musical instrument or sing a song. However, not all composers have willingness to share their own sheet music, especially those protected by strict copyright regulations. For amateurs or novice musicians without the capability to distinguish the chords by their own ears, it would be difficult for them to enjoy the happiness of playing other's music, or singing songs. In order to provide the beginners with an effective way to play music or sing songs without a given sheet music, we developed a sheet music generator - “DeepSheet”, which was engineered based on deep learning techniques. Basically, the DeepSheet system is mainly composed of three distinctive components as follows: 1. voice separation of the audio song, 2. chord estimation of the background music, and 3. alignment of lyrics and music beats. The experimental results drawn from more than 150 songs of the Beatles and Queen indicated that the newly developed DeepSheet system has the capability and sensibility to generate sheet music with accuracy of approximately 76%.","Title: High-level semantic photographic composition analysis and understanding with deep neural networks\nYear: 2017\n\nAbstract: In order to take better photos, it is a fundamental step for the beginners of photography to learn basic photo composition rules. However, there are no tools developed to help beginners analyze the composition rules in given photos. Thus, in this study we developed a system with the capability to identify 12 common composition rules in a photo. It should be noted that some of the 12 common composition rules have not been considered by the previous studies, and this deficit gives this study its significance and appropriateness. In particular, we utilized deep neural networks (DNN) to extract high-level semantic features for facilitating the further analysis of photo composition rules. In order to train the DNN model, our research team constructed a dataset, which is collected from some famous photo websites, such as DPChallenge, Flicker, and Unsplash. All the collected photos were later labelled with 12 composition rules by a wide range of raters recruited from Amazon Mechanical Turk (AMT). Two DNN architectures (AlexNet and GoogLeNet) were then employed to build our system based on the collected dataset. The representative features of each composition rule were further visualized in our system. The results showed the feasibility of the proposed system and revealed the possibility of using this system to assist potential users to improve their photographical skills and expertise.","Title: Ontlus: 3D Content Collaborative Creation via Virtual Reality.\nYear: 2018\n\nAbstract: 3D content creation is usually done by commercial software like Maya and 3ds Max, or shareware like Blender. However, most of the current 3D modeling software tend to edit the content via 2D screen, which is not efficient and intuitive. In this work, we develop a virtual reality (VR) system, in which the user can not only create 3D content easily and smoothly but also collaborate with other users in the VR environment to accomplish their 3D design project. We use HTC VIVE to display the immersive designing environment and realize the interaction between the user and the 3D content. Through VIVE controllers, the users can perform painting, sculpturing, coloring, transformation, and multi-editor collaboration in the 3D virtual space. Compared with the traditional 3D modeling software, directly editing 3D content in the 3D VR environment is more user-friendly.","Title: Syncgan: Synchronize the Latent Spaces of Cross-Modal Generative Adversarial Networks\nYear: 2018\n\nAbstract: Generative adversarial network (GAN) has achieved impressive success on cross-domain generation, but it faces difficulty in cross-modal generation due to the lack of a common distribution between heterogeneous data. Most existing methods of conditional based cross-modal GANs adopt the strategy of one-directional transfer and have achieved preliminary success on text-to-image transfer. Instead of learning the transfer between different modalities, we aim to learn a synchronous latent space representing the cross-modal common concept. A novel network component named synchronizer is proposed in this work to judge whether the paired data is synchronous/corresponding or not, which can constrain the latent space of generators in the GANs. Our GAN model, named as SyncGAN, can successfully generate synchronous data (e.g., a pair of image and sound) from identical random noise. For transforming data from one modality to another, we recover the latent code by inverting the mappings of a generator and use it to generate data of different modality. In addition, the proposed model can achieve semi-supervised learning, which makes our model more flexible for practical applications.","Title: Train in Virtual Court: Basketball Tactic Training via Virtual Reality.\nYear: 2017\n\nAbstract: In this paper, we present a basketball tactic training system based on multimedia and virtual reality (VR) technologies to improve the effectiveness and experience of tactic learning. A tablet-based digital tactic board (2D BTB) is developed to draw, select, or search for a target offensive tactic. The 2D player trajectories of the target tactic are then converted into 3D player animation immediately to provide virtual reality content for experiencing and practicing the target basketball tactic. Through the VR environment, the learner can vividly experience how a tactic is executed in a global view or from a specific player's viewing direction. The basketball tactic movement guidance and virtual defenders are rendered in our VR system according to the target offensive tactic and the learner's head pose. We also design an experimental process to validate that the proposed VR training system not only makes the learner feel more like playing in a real basketball game but also improves the efficiency and effectiveness of learning new basketball tactics.","Title: Doodle Master: A Doodle Beautification System Based on Auto-encoding Generative Adversarial Networks.\nYear: 2018\n\nAbstract: For those people without artistic talent, they can only draw rough or even awful doodles to express their ideas. We propose a doodle beautification system named Doodle Master, which can transfer a rough doodle to a plausible image and also keep the semantic concepts of the drawings. The Doodle Master applies the VAE/GAN model to decode and generate the beautified result from a constrained latent space. To achieve better performance for sketch data which is more like discrete distribution, a shared-weight method is proposed to improve the learnt features of the discriminator with the aid of the encoder. Furthermore, we design an interface for the user to draw with basic drawing tools and adjust the number of reconstruction times. The experiments show that the proposed Doodle Master system can successfully beautify the rough doodle or sketch in real-time.","Title: Local Binary Pattern Circuit Generator With Adjustable Parameters for Feature Extraction.\nYear: 2018\n\nAbstract: In the field of computer vision, local binary pattern (LBP) is one of the most popular feature extraction method and has been used in many object detection frameworks. To efficiently extract LBP features in high-resolution images, hardware architecture is needed to disperse CPU burden and to improve the entire object detection performance. In this paper, a hardware implementation of an approximate...","Title: ORSNet: A Hybrid Neural Network for Official Sports Referee Signal Recognition.\nYear: 2018\n\nAbstract: In this work, we propose a novel sports referee training system based on wearable sensors and a real-time Official Referee Signal (ORS) segmentation/recognition method which can recognize 65 kinds basketball ORSs with the accuracy of 95.3%. A hybrid neural network named ORSNet is designed for recognizing gestures based on IMU signals. The proposed ORSNet involves convolution layers and recurrent layers to learn more representative features and correlations in temporal domain, respectively. A novel loss function and a weight sharing strategy are proposed to learn a more robust ORS recognition model. Moreover, we investigate the influence of applying a semi-supervised network in the proposed ORSNet.","Title: A lightweight and efficient system for tracking handheld objects in virtual reality\nYear: 2018\n\nAbstract: While the content of virtual reality (VR) has grown explosively in recent years, the advance of designing user-friendly control interfaces in VR still remains a slow pace. The most commonly used device, such as gamepad or controller, has fixed shape and weight, and thus can not provide realistic haptic feedback when interacting with virtual objects in VR. In this work, we present a novel and lightweight tracking system in the context of manipulating handheld objects in VR. Specifically, our system can effortlessly synchronize the 3D pose of arbitrary handheld objects between the real world and VR in realtime performance. The tracking algorithm is simple, which delicately leverages the power of Leap Motion and IMU sensor to respectively track object's location and orientation. We demonstrate the effectiveness of our system with three VR applications use pencil, ping-pong paddle, and smartphone as control interfaces to provide users more immersive VR experience.","Title: Automated tongue diagnosis on the smartphone and its applications.\nYear: 2019\n\nAbstract: •We propose a SVM-based lighting condition estimation method according to color differences of tongue images taken with and without flash on the smartphone under different lighting conditions.•We then train a tongue image color correction matrix for each lighting condition based on the ColorChecker to remove the effect of color distortion. The effects of different model parameters and ColorCheckers on the performance of color correction are also discussed. Finally, in order to demonstrate the potential use of our proposed system, we recruited 246 patients and examined the correlations between the captured tongue features and ALT/ AST.•We found that some tongue features have strong correlation with the AST or ALT, which suggests the possible use of these tongue features captured on a smartphone to provide an early warning of liver diseases.","Title: Furniture style compatibility recommendation with cross-class triplet loss.\nYear: 2019\n\nAbstract: Harmonizing the style of all the furniture placed within a constrained space/scene is an important principle for interior design. In this paper, we propose a furniture style compatibility recommendation approach for users to create a harmonic 3D virtual scene based on 2D furniture photos. Most previous works of 3D model style analysis measure the style similarity or compatibility based on predefined geometric features extracted from 3D models. However, “style” is a high-level semantic concept, which is difficult to be described explicitly by hand-crafted geometric features. Moreover, analyzing the style compatibility between two or more furniture belonging to different classes (e.g., table and lamp) is much more challenging since the given furniture may have very distinctive structures or geometric elements. Recently, deep neural network has been claimed to have more powerful ability to mimic the perception of human visual cortex, and therefore we propose to analyze style compatibility between 3D furniture models of different classes based on a Cross-Class Triplet Convolutional Neural Network (CNN). We conducted experiments based on a collected dataset containing 420 textured 3D furniture models. A group of raters were recruited from Amazon Mechanical Turk (AMT) to evaluate the comparative suitability of paired models within the dataset. The experimental results reveal that the proposed furniture style compatibility method based on deep learning performs better than the state-of-the-art method and can be used to efficiently generate harmonic virtual scenes.","Title: Training assistant: strengthen your tactical nous with proficient virtual basketball players\nYear: 2018\n\nAbstract: Tactic training plays a crucial role in basketball offensive plays. With the aid of virtual reality, we propose a framework to improve the effectiveness and experience of tactic learning. The framework consists of a tactic input device and a wireless VR interaction system, which allows the user to conveniently input target tactic and practice in a high-fidelity circumstance. By the assistance of our VR training system, the user can vividly experience how the tactics are executed by viewing from the a specific player's viewing direction. Additionally, tactic movement guidance, action hint of how to offense aggressively, and virtual defenders are rendered in our system to make the training more realistic. By using the proposed framework, players can strengthen their tactical nous and improve the efficiency of tactic training.","Title: Handwriting Trajectory Reconstruction Using Low-Cost IMU.\nYear: 2019\n\nAbstract: In this paper, we propose a trajectory reconstruction method based on low-cost Inertial Measurement Unit (IMU) in smartphones. The IMU used in our work consists of a three-axis accelerometer and a three-axis gyroscope, which can record information of acceleration and rotation, respectively. Since intrinsic bias and random noise usually cause unreliable IMU signals, filtering methods are utilized t...","Title: MultiMedia Modeling - 26th International Conference, MMM 2020, Daejeon, South Korea, January 5-8, 2020, Proceedings, Part I.\nYear: 2020\n\nAbstract: The two-volume set LNCS 11961 and 11962 constitutes the thoroughly refereed proceedings of the 25th International Conference on MultiMedia Modeling, MMM 2020, held in Daejeon, South Korea, in January 2020.Of the 171 submitted full research papers, 40 papers were selected for oral presentation and 46 for poster presentation; 28 special session papers were selected for oral presentation and 8 for poster presentation; in addition, 9 demonstration papers and 6 papers for the Video Browser Showdown 2020 were accepted. The papers of LNCS 11961 are organized in the following topical sections: audio and signal processing; coding and HVS; color processing and art; detection and classification; face; image processing; learning and knowledge representation; video processing; poster papers; the papers of LNCS 11962 are organized in the following topical sections: poster papers; AI-powered 3D vision …","Title: MultiMedia Modeling - 26th International Conference, MMM 2020, Daejeon, South Korea, January 5-8, 2020, Proceedings, Part II.\nYear: 2020\n\nAbstract: The two-volume set LNCS 11961 and 11962 constitutes the thoroughly refereed proceedings of the 25th International Conference on MultiMedia Modeling, MMM 2020, held in Daejeon, South Korea, in January 2020. Of the 171 submitted full research papers, 40 papers were selected for oral presentation and 46 for poster presentation; 28 special session papers were selected for oral presentation and 8 for poster presentation; in addition, 9 demonstration papers and 6 papers for the Video Browser Showdown 2020 were accepted. The papers of LNCS 11961 are organized in the following topical sections: audio and signal processing; coding and HVS; color processing and art; detection and classification; face; image processing; learning and knowledge representation; video processing; poster papers; the papers of LNCS 11962 are organized in the following topical sections: poster papers; AI-powered 3D vision; multimedia analytics: perspectives, tools and applications; multimedia datasets for repeatable experimentation; multi-modal affective computing of large-scale multimedia data; multimedia and multimodal analytics in the medical domain and pervasive environments; intelligent multimedia security; demo papers; and VBS papers.","Title: STR-GQN - Scene Representation and Rendering for Unknown Cameras Based on Spatial Transformation Routing.\nYear: 2021\n\nAbstract: Geometry-aware modules are widely applied in recent deep learning architectures for scene representation and rendering. However, these modules require intrinsic camera information that might not be obtained accurately. In this paper, we propose a Spatial Transformation Routing (STR) mechanism to model the spatial properties without applying any geometric prior. The STR mechanism treats the spatial transformation as the message passing process, and the relation between the view poses and the routing weights is modeled by an end-to-end trainable neural network. Besides, an Occupancy Concept Mapping (OCM) framework is proposed to provide explainable rationals for scene-fusion processes. We conducted experiments on several datasets and show that the proposed STR mechanism improves the performance of the Generative Query Network (GQN). The visualization results reveal that the routing process can pass the observed information from one location of some view to the associated location in the other view, which demonstrates the advantage of the proposed model in terms of spatial cognition.","Title: Reducing Library Characterization Time For Cell-Aware Test While Maintaining Test Quality\nYear: 2021\n\nAbstract: Cell-aware test (CAT) explicitly targets faults caused by defects inside library cells to improve test quality, compared with conventional automatic test pattern generation (ATPG) approaches, which target faults only at the boundaries of library cells. The CAT methodology consists of two stages. Stage 1, based on dedicated analog simulation, library characterization per cell identifies which cell-level test pattern detects which cell-internal defect; this detection information is encoded in a defect detection matrix (DDM). In Stage 2, with the DDMs as inputs, cell-aware ATPG generates chip-level test patterns per circuit design that is build up of interconnected instances of library cells. This paper focuses on Stage 1, library characterization, as both test quality and cost are determined by the set of cell-internal defects identified and simulated in the CAT tool flow. With the aim to achieve the best test quality, we first propose an approach to identify a comprehensive set, referred to as full set, of potential open- and short-defect locations based on cell layout. However, the full set of defects can be large even for a single cell, making the time cost of the defect simulation in Stage 1 unaffordable. Subsequently, to reduce the simulation time, we collapse the full set to a compact set of defects which serves as input of the defect simulation. The full set is stored for the diagnosis and failure analysis. With inspecting the simulation results, we propose a method to verify the test quality based on the compact set of defects and, if necessary, to compensate the test quality to the same level as that based on the full set of defects. For 351 combinational library cells in Cadence's GPDK045 45nm library, we simulate only 5.4% defects from the full set to achieve the same test quality based on the full set of defects. In total, the simulation time, via linear extrapolation per cell, would be reduced by 96.4% compared with the time based on the full set of defects.","Title: Semi-supervised Many-to-many Music Timbre Transfer\nYear: 2021\n\nAbstract: ABSTRACTThis work presents a music timbre transfer model that aims to transfer the style of a music clip while preserving the semantic content. Compared to the existing music timbre transfer models, our model can achieve many-to-many timbre transfer between different instruments. The proposed method is based an autoencoder framework, which comprises two pretrained encoders trained in a supervised manner and one decoder trained in an unsupervised manner. To learn more representative features for the encoders, we produced a parallel dataset, called MI-Para, which is synthesized from MIDI files and digital audio workstations (DAW). Both the objective and the subjective evaluation results showed the effectiveness of the proposed framework. To scale up the application scenario, we also demonstrate that our model can achieve style transfer by training in a semi-supervised manner with a smaller parallel dataset.","Title: MMArt-ACM'21: International Joint Workshop on Multimedia Artworks Analysis and Attractiveness Computing in Multimedia 2021\nYear: 2021\n\nAbstract: ABSTRACTThe International Joint Workshop on Multimedia Artworks Analysis and Attractiveness Computing in Multimedia (MMArt-ACM) solicits contributions on methodology advancement and novel applications of multimedia artworks and attractiveness computing that emerge in the era of big data and social media. The topics of the accepted papers cover an analytic topic on comic contents understanding to generative topics on image synthesis and conversion. The actual MMArt-ACM'21 Proceedings are available at: https://dl.acm.org/doi/proceedings/10.1145/3460426.","Title: Deep Model Style: Cross-Class Style Compatibility For 3d Furniture Within A Scene\nYear: 2017\n\nAbstract: Harmonizing the style of all the furniture placed within a constrained space/scene has been regarded as one of the most important tasks in interior design. Most previous style analysis works measure the style similarity or compatibility of the objects based on predefined geometric features extracted from 3D models. However, style\" is a high-level semantic concept, which is difficult to be described explicitly by hand-crafted geometric features. Deep neural network has been claimed to have more powerful ability to mimic the perception of human visual cortex. Therefore, in this work we utilize Triplet Convolutional Neural Network (Triplet CNN) to analyze style compatibility between 3D furniture models of different classes (e.g., a table and a lamp). It should be noted that analyzing the style compatibility between two or more furniture of different classes is quite difficult, as the given furniture may have distinctive structures or geometric elements. We conducted experiments based on a collected dataset containing 420 textured 3D furniture models. A group of raters were recruited from Amazon Mechanical Turk (AMT) to evaluate the comparative suitability of paired models within the dataset. The experimental results reveal that the proposed furniture style compatibility method based on deep learning is better than the state-of-the-art method and can be used for furniture recommendation.","Title: Investigating the Affective State of VR HMD User When Watching Videos Displayed in Different Formats\nYear: 2021\n\nAbstract: In recent years, many studies have discussed whether virtual reality (VR) can enhance the sensory experience of the audience via a controllable virtual environment. Most of the researches focus on comparing the difference of perceptual immersion between LCD screen and VR, or the impact on the narrative of the two media. The goal of this study is to investigate the affective state in VR head-mounte...","Title: Instant Basketball Defensive Trajectory Generation\nYear: 2022\n\nAbstract: AbstractTactic learning in virtual reality (VR) has been proven to be effective for basketball training. Endowed with the ability of generating virtual defenders in real time according to the movement of virtual offenders controlled by the user, a VR basketball training system can bring more immersive and realistic experiences for the trainee. In this article, an autoregressive generative model for instantly producing basketball defensive trajectory is introduced. We further focus on the issue of preserving the diversity of the generated trajectories. A differentiable sampling mechanism is adopted to learn the continuous Gaussian distribution of player position. Moreover, several heuristic loss functions based on the domain knowledge of basketball are designed to make the generated trajectories assemble real situations in basketball games. We compare the proposed method with the state-of-the-art works in terms of both objective and subjective manners. The objective manner compares the average position, velocity, and acceleration of the generated defensive trajectories with the real ones to evaluate the fidelity of the results. In addition, more high-level aspects such as the empty space for offender and the defensive pressure of the generated trajectory are also considered in the objective evaluation. As for the subjective manner, visual comparison questionnaires on the proposed and other methods are thoroughly conducted. The experimental results show that the proposed method can achieve better performance than previous basketball defensive trajectory generation works in terms of different evaluation metrics.","Title: Feasibility Study on Using AI and VR for Decision-Making Training of Basketball Players\nYear: 2021\n\nAbstract: Decision-making plays an essential role in basketball offense. Offensive players must make effective decisions to score a basket in various defensive situations. Virtual reality (VR) has been widely used in the training of athletes to strengthen their ability to make optimal decisions by creating controllable repeatable training scenarios. In this article, an action-aware offensive decision-making...","Title: An imitation learning framework for generating multi-modal trajectories from unstructured demonstrations\nYear: 2022\n\nAbstract: The main challenge of the trajectory generation problem is to generate long-term as well as diverse trajectories. Generative Adversarial Imitation Learning (GAIL) is a well-known model-free imitation learning algorithm that can be utilized to generate trajectory data, while vanilla GAIL would fail to capture multi-modal demonstrations. Recent methods propose latent variable models to solve this problem; however, previous works may have a mode missing problem. In this work, we propose a novel method to generate long-term trajectories that are controllable by a continuous latent variable based on GAIL and a conditional Variational Autoencoder (cVAE). We further assume that subsequences of the same trajectory should be encoded to similar locations in the latent space. Therefore, we introduce a contrastive loss in the training of the encoder. In our motion synthesis task, we propose to first construct a low-dimensional motion manifold by using a VAE to reduce the burden of our imitation learning model. Our experimental results show that the proposed model outperforms the state-of-the-art methods and can be applied to motion synthesis.","Title: Assist Home Training Table Tennis Skill Acquisition via Immersive Learning and Web Technologies\nYear: 2022\n\nAbstract: Sports applications in Virtual Reality (VR) have become immensely popular for training skill-based sports like table tennis. However, the existing researches do not focus on designing an intuitive system for efficient communication between the trainee and the coach. We developed a VR table tennis training system for table tennis skill acquisition that focuses on helping coaches to convey a trainee's mistake clearly. Our system consists of a VR training system where trainees can learn a skill gradually and a web-based feedback annotative tool for coaches. Trainees can examine their mistakes through a tablet or an immersive VR world.","Title: Computer Vision Based Cognition Assessment for Developmental-Behavioral Screening\nYear: 2022\n\nAbstract: Common screening tasks for developmental-behavioral disabilities require human judgement to decide pass/fail on checklists, which possibly causes subjective biases. On the other hand, professional requirements for an assessment build a barrier for the accessibility to such screening tests. Therefore, we applied a combination of computer vision techniques to automatically perform cognition assessment on toddlers. To tackle insufficient data, multi-person scene, and unexpected movements of toddlers, YOLOv5, Mediapipe, LOFTR, and depth prediction model trained from Mannequin Challenge dataset are utilized to accurately focus our detection model on assigned areas to generate better results. We believe that similar concepts could be further extended to other sub-fields in childhood developmental-behavioral screening and improve clinical practice.","Title: ScoreActuary: Hoop-Centric Trajectory-Aware Network for Fine-Grained Basketball Shot Analysis\nYear: 2022\n\nAbstract: ABSTRACTWe propose a fine-grained basketball shot analysis system called ScoreActuary to analyze the players' shot events, which can be applied to game analysis, player training, and highlight generation. Given a basketball video as input, our system first detects/segments shot candidates and then analyzes \"Shot Type\", \"Shot Result\", and \"Ball Status\" of each shot candidate in real-time. Our approach is composed of a customized object detector and a trajectory-aware network to learn the information of ball trajectory. Compared to the existing methods that analyze basketball shots, our algorithm can better handle videos with arbitrary camera movements while improving the accuracy. To the best of our knowledge, this work is the first system that can analyze fine-grained shot events accurately in real basketball games with arbitrary camera movements.","Title: BetterSight: Immersive Vision Training for Basketball Players\nYear: 2022\n\nAbstract: ABSTRACTVision training is important for athletes and is key to win a sports game. Traditional vision training methods are suitable for sports that focus only on the ball. For basketball, however, players need to observe multiple moving objects (i.e., ball and players) concurrently on a large court. We propose BetterSight, an immersive vision training system for basketball that not only trains the vision of the player but also requires the player to dribble the ball stably, mimicking the situation in a real basketball game. BetterSight is composed of an Interaction Module (IM), a Training Content Generation Module (TCGM), and an Analysis Module (AM). IM allows the trainee to interact with the system more intuitively based on gesture and speech rather than the controller. TCGM simulates the training scenarios based on the training configurations selected by the trainee. AM collects the video sequences capturing the trainee and the trainee's eye movements during the training phase, and then analyzes the trainee's gaze, dribbling movements, and number of dribbles. The analyzed data can be used to evaluate the training effectiveness of using the proposed BetterSight.","Title: StimulusLoop: Game-Actuated Mutuality Artwork for Evoking Affective State\nYear: 2022\n\nAbstract: ABSTRACTAs transmission technology has advanced, large-scale media data is delivered to users. However, machines may collect user behavior while users are receiving messages and analyze how to stimulate users' senses to grab more attention. To demonstrate the relationship between machines and users, we propose a game-actuated mutuality artwork, StimulusLoop. We design the visualization to present the users' behavior and affective state and design the game mechanics that one participant throws the dart to change the video watched by the other participant. The interactions between two participants form a game loop, and different kinds of messages passing between the two participants are visualized as mutuality artwork.","Title: GetWild: A VR Editing System with AI-Generated 3D Object and Terrain\nYear: 2022\n\nAbstract: ABSTRACT3D environment artists typically use 2D screens and 3D modeling software to achieve their creation. However, creating 3D content using 2D tools is counterintuitive. Moreover, the process would be inefficient for junior artists in the absence of a reference. We develop a system called GetWild, which employs artificial intelligence (AI) models to generate the prototype of 3D objects/terrain and allows users to further edit the generated content in the virtual space. With the aid of AI, the user can capture an image to obtain a rough 3D object model, or start with drawing simple sketches representing the river, the mountain peak and the mountain ridge to create a 3D terrain prototype. Further, the virtual reality (VR) technique is used to provide an immersive design environment and intuitive interaction (such as painting, sculpturing, coloring, and transformation) for users to edit the generated prototypes. Compared with the existing 3D modeling software and systems, the proposed VR editing system with AI-generated 3D objects/terrain provides a more efficient way for the user to create virtual artwork."],"string":"[\n \"Title: Tennis Real Play\\nYear: 2012\\n\\nAbstract: Tennis Real Play (TRP) is an interactive tennis game system constructed with models extracted from videos of real matches. The key techniques proposed for TRP include player modeling and video-based player/court rendering. For player model creation, we propose the process for database normalization and the behavioral transition model of tennis players, which might be a good alternative for motion capture in the conventional video games. For player/court rendering, we propose the framework for rendering vivid game characters and providing the real-time ability. We can say that image-based rendering leads to a more interactive and realistic rendering. Experiments show that video games with vivid viewing effects and characteristic players can be generated from match videos without much user intervention. Because the player model can adequately record the ability and condition of a player in the real world, it can then be used to roughly predict the results of real tennis matches in the next days. The results of a user study reveal that subjects like the increased interaction, immersive experience, and enjoyment from playing TRP.\",\n \"Title: TravelBuddy: Interactive Travel Route Recommendation with a Visual Scene Interface\\nYear: 2014\\n\\nAbstract: In this work, we propose a convenient system for trip planning and aim to change the behavior of trip planners from exhaustively searching information to receiving useful travel recommendations. Given the essential and optional user inputs, our system automatically recommends a route that suits the traveler based on a real-time route planning algorithm and allows the user to make adjustment according to their preferences. We construct a traveling database by collecting photos taken around famous attractions and analyzing these photos to extract each attraction's travel information including popularity, typical stay time, available visiting time in a day, and visual scenes of different time. All the extracted travel information are presented to the user to help him/her efficiently know more about different attractions so that he/she can modify the inputs to obtain a more favorable travel route. The experimental results show that our system can effectively help the user to plan the journey.\",\n \"Title: Efficient human detection in crowded environment based on motion and appearance information\\nYear: 2013\\n\\nAbstract: Detecting human in crowded environment is profitable but challenging in video surveillance. We propose an efficient human detection method by combining both motion and appearance clues. Moving pixels are first extracted by background subtraction, and then a filtering step is used to narrow the range for human template matching. We utilize integral images to fast generate shape information from edge maps of each frame and define the matching probability to be capable of detecting both full-body and partial-body. Representative human templates are constructed by sparse contours on the basis of the point distribution model (PDM). Moreover, linear regression analysis is also applied to adaptively adjust the template sizes. With the aid of the proposed foreground ratio filtering and the multi-sized template matching techniques, our method not only can efficiently detect human in a crowded environment but also largely enhance the detection accuracy.\",\n \"Title: Actions speak louder than words: searching human action video based on body movement\\nYear: 2012\\n\\nAbstract: Human action video search is a frequent demand in multimedia applications, and conventional video search schemes based on keywords usually fail to correctly find relevant videos due to noisy video tags. Observing the widespread use of Kinect-like depth cameras, we propose to search human action videos by directly performing the target action with body movements. Human actions are captured by Kinect and the recorded depth information is utilized to measure the similarity between the query action and each human action video in the database. We use representative depth descriptors without learning optimization to achieve real-time and promising performance as compatible as those of the leading methods based on color images and videos. Meanwhile, a large Depth-included Human Action video dataset, namely DHA, is collected to prove the effectiveness of the proposed video search system.\",\n \"Title: Who's the Best Charades Player? Mining Iconic Movement of Semantic Concepts\\nYear: 2014\\n\\nAbstract: Charades is a guessing game with the idea for one player to act out a semantic concept (i.e. a word or phrase) for the other players to guess. An observation from playing charades is that people's cognition on the iconic movements associated with a semantic concept would be often inconsistent, and this fact has long been ignored in the multimedia research. Therefore, the novelty of this work is to propose an automation for mining the most representative videos for each semantic concept as its iconic movements from a large set of related videos containing various human actions. The discovered iconic movements can be further employed to benefit a broad range of tasks, such as human action recognition and retrieval. For our purpose, a new video benchmark is also presented and the experiments demonstrated our approach potential to human action based applications.\",\n \"Title: Learning and Recognition of On-Premise Signs From Weakly Labeled Street View Images\\nYear: 2014\\n\\nAbstract: Camera-enabled mobile devices are commonly used as interaction platforms for linking the user's virtual and physical worlds in numerous research and commercial applications, such as serving an augmented reality interface for mobile information retrieval. The various application scenarios give rise to a key technique of daily life visual object recognition. On-premise signs (OPSs), a popular form of commercial advertising, are widely used in our living life. The OPSs often exhibit great visual diversity (e.g., appearing in arbitrary size), accompanied with complex environmental conditions (e.g., foreground and background clutter). Observing that such real-world characteristics are lacking in most of the existing image data sets, in this paper, we first proposed an OPS data set, namely OPS-62, in which totally 4649 OPS images of 62 different businesses are collected from Google's Street View. Further, for addressing the problem of real-world OPS learning and recognition, we developed a probabilistic framework based on the distributional clustering, in which we proposed to exploit the distributional information of each visual feature (the distribution of its associated OPS labels) as a reliable selection criterion for building discriminative OPS models. Experiments on the OPS-62 data set demonstrated the outperformance of our approach over the state-of-the-art probabilistic latent semantic analysis models for more accurate recognitions and less false alarms, with a significant 151.28% relative improvement in the average recognition rate. Meanwhile, our approach is simple, linear, and can be executed in a parallel fashion, making it practical and scalable for large-scale multimedia applications.\",\n \"Title: Gait-based action recognition via accelerated minimum incremental coding length classifier\\nYear: 2012\\n\\nAbstract: In this paper, we present a novel human action recognition approach based on gait energy image (GEI) and minimum incremental coding length (MICL) classifier. GEIs are extracted from video clips and transformed into vectors as input features, and MICL is employed to classify each GEI. We also use multiple cameras to capture GEIs of different views, and the voting strategy is applied after the MICL classification results to improve the overall system performance. Experimental results show that the proposed approach can achieve approximately 95% of accuracy. For practical usage, we also speed up the classification time so that it can be accomplished in a very short time. Moreover, other classification methods are used to classify GEIs and the experimental result shows that MICL is the most suitable classifier for this approach. Besides our recorded action clips, the Weizmann dataset is also used to verify the capability of our approach. The experimental results show that our approach is competitive to other state-of-the-art action recognition methods.\",\n \"Title: Robust Camera Calibration and Player Tracking in Broadcast Basketball Video\\nYear: 2011\\n\\nAbstract: With the growth of fandom population, a considerable amount of broadcast sports videos have been recorded, and a lot of research has focused on automatically detecting semantic events in the recorded video to develop an efficient video browsing tool for a general viewer. However, a professional sportsman or coach wonders about high level semantics in a different perspective, such as the offensive or defensive strategy performed by the players. Analyzing tactics is much more challenging in a broadcast basketball video than in other kinds of sports videos due to its complicated scenes and varied camera movements. In this paper, by developing a quadrangle candidate generation algorithm and refining the model fitting score, we ameliorate the court-based camera calibration technique to be applicable to broadcast basketball videos. Player trajectories are extracted from the video by a CamShift-based tracking method and mapped to the real-world court coordinates according to the calibrated results. The player position/trajectory information in the court coordinates can be further analyzed for professional-oriented applications such as detecting wide open event, retrieving target video clips based on trajectories, and inferring implicit/explicit tactics. Experimental results show the robustness of the proposed calibration and tracking algorithms, and three practicable applications are introduced to address the applicability of our system.\",\n \"Title: Human action recognition and retrieval using sole depth information\\nYear: 2012\\n\\nAbstract: Observing the widespread use of Kinect-like depth cameras, in this work, we investigate into the problem of using sole depth data for human action recognition and retrieval in videos. We proposed the use of simple depth descriptors without learning optimization to achieve promising performances as compatible to those of the leading methods based on color images and videos, and can be effectively applied for real-time applications. Because of the infrared nature of depth cameras, the proposed approach will be especially useful under poor lighting conditions, e.g. the surveillance environments without sufficient lighting. Meanwhile, we proposed a large Depth-included Human Action video dataset, namely DHA, which contains 357 videos of performed human actions belonging to 17 categories. To the best of our knowledge, the DHA is one of the largest depth-included video datasets of human actions.\",\n \"Title: Interactive digital scrapbook generation for travel photos based on design principles of typography\\nYear: 2011\\n\\nAbstract: To facilitate the photo management and sharing tasks, many application tools have been developed to generate pleasant photo slideshows, collages, or scrapbooks by applying simple templates/layouts and visual effects. In this work, we propose a convenient digital scrapbook generating system for travel photos, named as IS-Scrapbook, which keeps the virtues while dismisses the drawbacks of conventional digital photo presentation styles. The IS-Scrapbook system has three friendly attributes compared to other photo presentation tools. First, aiming to attract the audience, we highlight objects more meaningful or familiar to the viewer, e.g. the landmark and the protagonist in the photos. Second, five basic design principles of typography, i.e. proximity, contrast, balance, color harmony and repetition, are applied to produce more vivacious layouts. Third, the system automatically generates a digital scrapbook with a default layout, and the user can further adjust photo positions and enrich each page by sketching or inserting dialog bubbles with the aid of the developed user interface. User study shows that the proposed work enhances the experiences of photo browsing and gives a brand-new way of photo sharing.\",\n \"Title: Traveling through space-time: an interactive photo browsing system\\nYear: 2012\\n\\nAbstract: Digital photos are estimated to be generated and uploaded to social image websites (e.g. Flickr) in the amount of 375 petabytes annually [Tueld et al.], and plenty of these photos are annotated with the creation time/date in EXIF information. Among these photos, a large number of images are geo-tagged (e.g. GPS and landmark names) to indicate where the photo was taken. Moreover, several public databases composed of pictures captured by live cameras at various locations are available on the internet. Therefore, it has become a crucial task to enable an intuitive and efficient way for users to browse large-scale photos in space and time.\",\n \"Title: Action tutor: real-time exemplar-based sequential movement assessment with kinect sensor\\nYear: 2012\\n\\nAbstract: With the aid of depth camera, such as Microsoft Kinect, the difficulty of vision-based posture estimation is greatly decreased, and human action analysis has achieved a wide range of applications. However, there is still much to do to develop effective movement assessment technique, which bridges the results of human posture estimation and the understanding of human action performance. In this work, we propose an action tutor system which enables the user to interactively retrieve the learning exemplar of the target action movement and to immediately acquire motion instructions while learning it in front of the Kinect. In the retrieval stage, non-linear time warping algorithms are designed to retrieve video segments similar to the query movement roughly performed by the user. In the learning stage, the user learns according to the selected video exemplar, and the motion assessment including both static and dynamic differences is presented to the user in a more effective and organized way, helping him/her to perform the action movement correctly.\",\n \"Title: Rectangling Stereographic Projection for Wide-Angle Image Visualization\\nYear: 2013\\n\\nAbstract: This paper proposes a new projection model for mapping a hemisphere to a plane. Such a model can be useful for viewing wide-angle images. Our model consists of two steps. In the first step, the hemisphere is projected onto a swung surface constructed by a circular profile and a rounded rectangular trajectory. The second step maps the projected image on the swung surface onto the image plane through the perspective projection. We also propose a method for automatically determining proper parameters for the projection model based on image content. The proposed model has several advantages. It is simple, efficient and easy to control. Most importantly, it makes a better compromise between distortion minimization and line preserving than popular projection models, such as stereographic and Pannini projections. Experiments and analysis demonstrate the effectiveness of our model.\",\n \"Title: Efficient human detection in crowded environment\\nYear: 2015\\n\\nAbstract: Detecting humans in crowded environment is profitable but challenging in video surveillance. We propose an efficient human detection method by combining both motion and appearance clues. Moving pixels are first extracted by background subtraction, and then a filtering step is used to narrow the range for human template matching. We utilize integral images to fast generate shape information from edge maps of each frame and define the matching probability to be capable of detecting both full-body and partial-body. Representative human templates are constructed by sparse contours on the basis of the point distribution model. Moreover, linear regression analysis is also applied to adaptively adjust the template sizes. With the aid of the proposed foreground ratio filtering and the multi-sized template matching techniques, experimental results show that our method not only can efficiently detect humans in a crowded environment, but also largely enhance the resultant detection accuracy.\",\n \"Title: Real-time human movement retrieval and assessment with Kinect sensor.\\nYear: 2015\\n\\nAbstract: The difficulty of vision-based posture estimation is greatly decreased with the aid of commercial depth camera, such as Microsoft Kinect. However, there is still much to do to bridge the results of human posture estimation and the understanding of human movements. Human movement assessment is an important technique for exercise learning in the field of healthcare. In this paper, we propose an action tutor system which enables the user to interactively retrieve a learning exemplar of the target action movement and to immediately acquire motion instructions while learning it in front of the Kinect. The proposed system is composed of two stages. In the retrieval stage, nonlinear time warping algorithms are designed to retrieve video segments similar to the query movement roughly performed by the user. In the learning stage, the user learns according to the selected video exemplar, and the motion assessment including both static and dynamic differences is presented to the user in a more effective and organized way, helping him/her to perform the action movement correctly. The experiments are conducted on the videos of ten action types, and the results show that the proposed human action descriptor is representative for action video retrieval and the tutor system can effectively help the user while learning action movements.\",\n \"Title: Eat as much as you can: a kinect-based facial rehabilitation game based on mouth and tongue movements\\nYear: 2014\\n\\nAbstract: In this demo, we present a Kinect-based interactive game which provides patients of facial palsy with a better and more fun way to perform facial physical therapy. By letting the user get scores when he/she bites or licks the virtual foods falling from the sky, the game goads the user into exercising their facial muscles. A robust bite action detector and an efficient tip-of-tongue locating method are developed to realize this game. Based on the head pose estimated by the depth clue, we classify the face orientation and locate the mouth region in each frame. The movements of lips are measured to detect the bite action, and different strategies are designed to more accurately detect the tip-of-tongue for various face orientations. The experimental results show that our method can be successfully applied to different users.\",\n \"Title: Efficient QR Code Beautification with High Quality Visual Content\\nYear: 2015\\n\\nAbstract: QR code is generally used for embedding messages such that people can conveniently use mobile devices to capture the QR code and acquire information through a QR code reader. In the past, the design of QR code generators only aimed to achieve high decodability and the produced QR codes usually look like random black-and-white patterns without visual semantics. In recent years, researchers have been tried to endow the QR code with aesthetic elements and QR code beautification has been formulated as an optimization problem that minimizes the visual perception distortion subject to acceptable decoding rate. However, the visual quality of the QR code generated by existing methods still leaves much to be desired. In this work, we propose a two-stage approach to generate QR code with high quality visual content. In the first stage, a baseline QR code with reliable decodability but poor visual quality is first synthesized based on the Gauss-Jordan elimination procedure. In the second stage, a rendering mechanism is designed to improve the visual quality while avoid affecting the decodability of the QR code. The experimental results show that the proposed method substantially enhances the appearance of the QR code and the processing complexity is near real-time.\",\n \"Title: Multimedia home environment streaming system design\\nYear: 2013\\n\\nAbstract: The consumer electronic devices become more popular, especially in the multimedia home environment. This paper presents a real-time scalable streaming system in home environment. The system is designed with a bandwidth adaptive control. In the implementation system, the server provides smooth SVC streaming for users with heterogeneous network environment. To again bandwidth fluctuation, the frame rate is adaptive according to bit rates with bandwidth condition. The scheme is implemented in the system with real streaming sequence test bench, the peak signal noise ratio (PSNR) improves in average 6.23% than the original JSVM software. Therefore, users have a smoothly video service during transmission in multimedia home environment.\",\n \"Title: Photo sundial: Estimating the time of capture in consumer photos.\\nYear: 2016\\n\\nAbstract: The time of capture of consumer photos provides rich information in temporal context and has been widely employed for solving various multimedia problems, such as multimedia retrieval and social media analysis. However, we observed that the recorded time stamp in a consumer photo does not often correspond to the true local time at which the photo was taken. This would greatly damage the robustness of time-aware multimedia applications, such as travel route recommendation. Therefore, motivated by the use of traditional sundials, this work proposes a system, Photo Sundial, for estimating the time of capture by exploiting the astronomical theory. In particular, we infer the time by establishing its relations to the measurable astronomical factors from a given outdoor photo, i.e. the sun position in the sky and the camera viewing direction in the photo-taken location. In practice, since it is more often that people would take multiple photos in a single trip, we further develop an optimization framework to jointly estimate the time from multiple photos. Experimental results show that the average estimated time error is less than 0.9h by the proposed approach, with a significant 65% relative improvement compared to the state-of-the-art method (2.5h). To the best of our knowledge, this work is the first study in multimedia research to explicitly address the problem of time of capture estimation in consumer photos, and the achieved performances highly encourage our system for practical applications.\",\n \"Title: Color Correction Parameter Estimation on the Smartphone and Its Application to Automatic Tongue Diagnosis.\\nYear: 2016\\n\\nAbstract: An automatic tongue diagnosis framework is proposed to analyze tongue images taken by smartphones. Different from conventional tongue diagnosis systems, our input tongue images are usually in low resolution and taken under unknown lighting conditions. Consequently, existing tongue diagnosis methods cannot be directly applied to give accurate results.We use the SVM (support vector machine) to predict the lighting condition and the corresponding color correction matrix according to the color difference of images taken with and without flash. We also modify the state-of-the-art work of fur and fissure detection for tongue images by taking hue information into consideration and adding a denoising step.Our method is able to correct the color of tongue images under different lighting conditions (e.g. fluorescent, incandescent, and halogen illuminant) and provide a better accuracy in tongue features detection with less processing complexity than the prior work.In this work, we proposed an automatic tongue diagnosis framework which can be applied to smartphones. Unlike the prior work which can only work in a controlled environment, our system can adapt to different lighting conditions by employing a novel color correction parameter estimation scheme.\",\n \"Title: B-box Mixer: An Interactive UI for Generating B-box Music\\nYear: 2015\\n\\nAbstract: B-box is a form of vocal percussion that imitates rhythms in various types of sound, especially musical instruments. As b-box becoming popular, more and more people want to learn b-box and make their own b-box music. However, not everyone has the talent for generating harmonic b-box music. In this work, we develop an interactive system which helps the user easily compose b-box music given two inputs: an unaccompanied vocal song and a piece of b-box rhythm. The audio signals of the two inputs are analyzed and adaptively matched on the basis of their beats. The state of the art beat detection technique does not perform well on vocal songs. Hence, we propose to partition the song into short segments and estimate the average tempo for each segment so that the adjustment of tempo will not be affected too much by the wrongly detected beats. With the proposed system, people who love b-box or are not familiar with b-box can enjoy producing their own b-box music.\",\n \"Title: Locality Constrained Sparse Representation for Cat Recognition.\\nYear: 2016\\n\\nAbstract: Cat (Felis catus) plays an important social role within our society and can provide considerable emotional support for their owners. Missing, swapping, theft, and false insurance claims of cat have become global problem throughout the world. Reliable cat identification is thus an essential factor in the effective management of the owned cat population. The traditional cat identification methods by permanent (e.g., tattoos, microchip, ear tips/notches, and freeze branding), semi-permanent (e.g., identification collars and ear tags), or temporary (e.g., paint/dye and radio transmitters) procedures are not robust to provide adequate level of security. Moreover, these methods might have adverse effects on the cats. Though the work on animal identification based on their phenotype appearance (face and coat patterns) has received much attention in recent years, however none of them specifically targets cat. In this paper, we therefore propose a novel biometrics method to recognize cat by exploiting their noses that are believed to be a unique identifier by cat professionals. As the pioneer of this research topic, we first collect a Cat Database that contains 700 cat nose images from 70 different cats. Based on this dataset, we design a representative dictionary with data locality constraint for cat identification. Experimental results well demonstrate the effectiveness of the proposed method compared to several state-of-the-art feature-based algorithms.\",\n \"Title: Representative photo selection for restaurants in food blogs\\nYear: 2015\\n\\nAbstract: Nowadays, people write comments of restaurants and upload related photos to food blogs after visiting there. Developing a mobile application which enables the user to effectively search restaurants from data in these blogs becomes an emerging need. Besides reading the comments, most people will give a glance at food photos of a restaurant and then decide whether to go or what to eat. Therefore, we propose a system to analyze and select representative photos for each restaurant based on blog-platform media. A strong food detection model is trained to retrieve food photos and an aesthetic quality assessment method is utilized to select representative photos. Based on these representative photos, users can more easily have the impression of the restaurant and review the blog in an organized way. The experimental results show that our system can generate better representative photos (i.e. much closer to the users' preferences) than existing blog platforms.\",\n \"Title: VRank: Voting system on Ranking model for human age estimation\\nYear: 2015\\n\\nAbstract: Ranking algorithms have proven the potential for human age estimation. Currently, a common paradigm is to compare the input face with reference faces of known age to generate a ranking relation whereby the first-rank reference is exploited for labeling the input face. In this paper, we proposed a framework to improve upon the typical ranking model, called Voting system on Ranking model (VRank), by leveraging relational information (comparative relations, i.e. if the input face is younger or older than each of the references) to make a more robust estimation. Our approach has several advantages: firstly, comparative relations can be explicitly involved to benefit the estimation task; secondly, few incorrect comparisons will not influence much the accuracy of the result, making this approach more robust than the conventional approach; finally, we propose to incorporate the deep learning architecture for training, which extracts robust facial features for increasing the effectiveness of classification. In comparison to the best results from the state-of-the-art methods, the VRank showed a significant outperformance on all the benchmarks, with a relative improvement of 5.74% ~ 69.45% (FG-NET), 19.09% ~ 68.71% (MORPH), and 0.55% ~ 17.73% (IoG).\",\n \"Title: Real-Time Sign Language Recognition in Complex Background Scene Based on a Hierarchical Clustering Classification Method\\nYear: 2016\\n\\nAbstract: Cameras are embedded in many mobile/wearable devices and can be used for gesture recognition or even sign language recognition to help the deaf people communicate with others. In this paper, we proposed a vision-based gesture recognition system which can be used in environments with complex background. We design a method to adaptively update the skin color model for different users and various lighting conditions. Three kinds of features are combined to describe the contours and the salient points of hand gestures. Principle Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Support Vector Machine (SVM) are integrated to construct a novel hierarchical classification scheme. We evaluated the proposed recognition method on two datasets: (1) the CSL dataset collected by ourselves, in which images were captured in complex background. (2) The public ASL dataset, in which images of the same gesture were captured in different lighting conditions. Our method achieves the accuracies of 99.8% and 94%, respectively, which outperforms the existing works.\",\n \"Title: A Framework of Enlarging Face Datasets Used for Makeup Face Analysis\\nYear: 2016\\n\\nAbstract: There have been lots of research about face detection and face recognition. However, faces with makeup usually seriously affect the face recognition result. If we want to recognize the face with higher accuracy, it would be better to first know whether the input face is with makeup or not, and we can use corresponding makeup face or non-makeup face model to recognize it. Unfortunately, the current available datasets for face analysis do not include enough makeup and non-makeup image pairs of users. In this work, we propose a framework to efficiently increase pairs of makeup and non-makeup face images for the existing makeup face datasets. Patch-based features are extracted and support vector machine (SVM) is applied to classify whether a face image is with makeup. The technique of partial least squares (PLS) is then employed to authenticate whether a makeup photo and a non-makeup photo belong to the same person. By combining the makeup detection and the face authentication methods, we can successfully construct a larger face dataset that can be specifically used for applications of makeup face analysis.\",\n \"Title: Immersive virtual reality with multimodal interaction and streaming technology.\\nYear: 2016\\n\\nAbstract: In this demo, we present an immersive virtual reality (VR) system which integrates multimodal interaction sensors (i.e., smartphone, Kinect v2, and Myo armband) and streaming technology to improve the VR experience. The integrated system solves the common problems in most VR systems: (1) the very limited playing area due to transmission cable between computer and display/interaction devices, and (2) non-intuitive way of controlling virtual objects. We use Unreal Engine 4 to develop an immersive VR game with 6 interactive levels to demonstrate the feasibility of our system. In the game, the user not only can freely walk within a large playing area surrounded by multiple Kinect sensors but also select the virtual objects to grab and throw with the Myo armband. The experiment shows that our idea is workable for VR experience.\",\n \"Title: A Sensor-Based Official Basketball Referee Signals Recognition System Using Deep Belief Networks.\\nYear: 2017\\n\\nAbstract: In a basketball game, basketball referees who have the responsibility to enforce the rules and maintain the order of the basketball game has only a brief moment to determine if an infraction has occurred, later they communicate with the scoring table using hand signals. In this paper, we propose a novel system which can not only recognize the basketball referees' signals but also communicate with the scoring table in real-time. Deep belief network and time-domain feature are utilized to analyze two heterogeneous signals, surface electromyography (sEMG) and three-axis accelerometer (ACC) to recognize dynamic gestures. Our recognition method is evaluated by a dataset of 9 various official hand signals performed by 11 subjects. Our recognition model achieves acceptable accuracy rate, which is 97.9% and 90.5% for 5-fold Cross Validation (5-foldCV) and Leave-One-Participant-Out Cross Validation (LOPOCV) experiments, respectively. The accuracy of LOPOCV experiment can be further improved to 94.3% by applying user calibration.\",\n \"Title: Tongue Fur Detection On The Smartphone\\nYear: 2016\\n\\nAbstract: Tongue fur is an important objective basis for clinical diagnosis and treatment in western medicine and tongue diagnosis for Chinese medicine. Given the high penetration and built-in sensors of smartphones, and the need for continuous monitoring of health conditions, we propose an automatic tongue diagnosis framework on smartphone. However, tongue images taken by smartphone are quite different in color due to various lighting conditions, so we have to solve this problem to detect the correct tongue furs. In previous work mentioned that their tongue diagnosis systems are set up in a constrained well-controlled environment (e.g. with fixed lighting condition), but we purpose to let users make tongue diagnosis with their own smartphones no matter where they are. Therefore, we provide a way to detect tongue furs under different lighting conditions (e.g. fluorescent, halogen, and incandescent illuminant) by the com bination of series methods: 1. Lighting condition estimation, 2. Tongue image color correction 3. Tongue fur (white fur) detection. We use the SVM to estimate the lighting condition and do the color correction with the corresponding correction matrix for current lighting condition. After getting the corrected tongue images, we use the detection model training by SVM to detect the white fur region in corrected tongue images. In this thesis, we propose a lighting condition estimation method according to color difference of tongue images taken with and without flash on the smartphone under different lighting condition; we also verify that it need to search corresponding parameter of correction matrix for color correction depend on different lighting condition; finally, we observe that the overlap rate of corrected tongue images for Hal. and Inc. lighting has been clearly upgraded with our correction parameter and the white fur can be identify if the overlap rate of corrected tongue images exceed 60%.\",\n \"Title: Recognition of Easily-confused TCM Herbs Using Deep Learning.\\nYear: 2017\\n\\nAbstract: Chinese herbal medicine (CHM) plays an important role of treatment in traditional Chinese medicine (TCM). Traditionally, CHM is used to restore the balance of the body for sick people and maintain health for common people. However, lack of the knowledge of the herbs may cause misuse of the herbs. In this demo, we will present a real-time smartphone application, which can not only recognize easily-confused herb based on Convolutional Neural Network (CNN), but also provide relevant information about the detected herbs. Our Chinese herb recognition system is implemented on a cloud server and can be used by the client user via smartphone. The recognition system is evaluated by 5-fold cross validation method and the accuracy is around 96%, which is adequate for real-world use.\",\n \"Title: Localization of Acupoints using Augmented Reality.\\nYear: 2017\\n\\nAbstract: An augmented reality (AR) system for acupuncture points localization is implemented on an Android smartphone. The user can utilize such a system to locate the relevant acupuncture point for the purpose of symptom relief (e.g. through acupressure).\",\n \"Title: DeepSheet: A sheet music generator based on deep learning\\nYear: 2017\\n\\nAbstract: Sheet music has long been regarded as one of the most effective medias for musicians, music players, and amateurs to communicate with each other. It is also an intuitive way for non-professionals to learn how to play a musical instrument or sing a song. However, not all composers have willingness to share their own sheet music, especially those protected by strict copyright regulations. For amateurs or novice musicians without the capability to distinguish the chords by their own ears, it would be difficult for them to enjoy the happiness of playing other's music, or singing songs. In order to provide the beginners with an effective way to play music or sing songs without a given sheet music, we developed a sheet music generator - “DeepSheet”, which was engineered based on deep learning techniques. Basically, the DeepSheet system is mainly composed of three distinctive components as follows: 1. voice separation of the audio song, 2. chord estimation of the background music, and 3. alignment of lyrics and music beats. The experimental results drawn from more than 150 songs of the Beatles and Queen indicated that the newly developed DeepSheet system has the capability and sensibility to generate sheet music with accuracy of approximately 76%.\",\n \"Title: High-level semantic photographic composition analysis and understanding with deep neural networks\\nYear: 2017\\n\\nAbstract: In order to take better photos, it is a fundamental step for the beginners of photography to learn basic photo composition rules. However, there are no tools developed to help beginners analyze the composition rules in given photos. Thus, in this study we developed a system with the capability to identify 12 common composition rules in a photo. It should be noted that some of the 12 common composition rules have not been considered by the previous studies, and this deficit gives this study its significance and appropriateness. In particular, we utilized deep neural networks (DNN) to extract high-level semantic features for facilitating the further analysis of photo composition rules. In order to train the DNN model, our research team constructed a dataset, which is collected from some famous photo websites, such as DPChallenge, Flicker, and Unsplash. All the collected photos were later labelled with 12 composition rules by a wide range of raters recruited from Amazon Mechanical Turk (AMT). Two DNN architectures (AlexNet and GoogLeNet) were then employed to build our system based on the collected dataset. The representative features of each composition rule were further visualized in our system. The results showed the feasibility of the proposed system and revealed the possibility of using this system to assist potential users to improve their photographical skills and expertise.\",\n \"Title: Ontlus: 3D Content Collaborative Creation via Virtual Reality.\\nYear: 2018\\n\\nAbstract: 3D content creation is usually done by commercial software like Maya and 3ds Max, or shareware like Blender. However, most of the current 3D modeling software tend to edit the content via 2D screen, which is not efficient and intuitive. In this work, we develop a virtual reality (VR) system, in which the user can not only create 3D content easily and smoothly but also collaborate with other users in the VR environment to accomplish their 3D design project. We use HTC VIVE to display the immersive designing environment and realize the interaction between the user and the 3D content. Through VIVE controllers, the users can perform painting, sculpturing, coloring, transformation, and multi-editor collaboration in the 3D virtual space. Compared with the traditional 3D modeling software, directly editing 3D content in the 3D VR environment is more user-friendly.\",\n \"Title: Syncgan: Synchronize the Latent Spaces of Cross-Modal Generative Adversarial Networks\\nYear: 2018\\n\\nAbstract: Generative adversarial network (GAN) has achieved impressive success on cross-domain generation, but it faces difficulty in cross-modal generation due to the lack of a common distribution between heterogeneous data. Most existing methods of conditional based cross-modal GANs adopt the strategy of one-directional transfer and have achieved preliminary success on text-to-image transfer. Instead of learning the transfer between different modalities, we aim to learn a synchronous latent space representing the cross-modal common concept. A novel network component named synchronizer is proposed in this work to judge whether the paired data is synchronous/corresponding or not, which can constrain the latent space of generators in the GANs. Our GAN model, named as SyncGAN, can successfully generate synchronous data (e.g., a pair of image and sound) from identical random noise. For transforming data from one modality to another, we recover the latent code by inverting the mappings of a generator and use it to generate data of different modality. In addition, the proposed model can achieve semi-supervised learning, which makes our model more flexible for practical applications.\",\n \"Title: Train in Virtual Court: Basketball Tactic Training via Virtual Reality.\\nYear: 2017\\n\\nAbstract: In this paper, we present a basketball tactic training system based on multimedia and virtual reality (VR) technologies to improve the effectiveness and experience of tactic learning. A tablet-based digital tactic board (2D BTB) is developed to draw, select, or search for a target offensive tactic. The 2D player trajectories of the target tactic are then converted into 3D player animation immediately to provide virtual reality content for experiencing and practicing the target basketball tactic. Through the VR environment, the learner can vividly experience how a tactic is executed in a global view or from a specific player's viewing direction. The basketball tactic movement guidance and virtual defenders are rendered in our VR system according to the target offensive tactic and the learner's head pose. We also design an experimental process to validate that the proposed VR training system not only makes the learner feel more like playing in a real basketball game but also improves the efficiency and effectiveness of learning new basketball tactics.\",\n \"Title: Doodle Master: A Doodle Beautification System Based on Auto-encoding Generative Adversarial Networks.\\nYear: 2018\\n\\nAbstract: For those people without artistic talent, they can only draw rough or even awful doodles to express their ideas. We propose a doodle beautification system named Doodle Master, which can transfer a rough doodle to a plausible image and also keep the semantic concepts of the drawings. The Doodle Master applies the VAE/GAN model to decode and generate the beautified result from a constrained latent space. To achieve better performance for sketch data which is more like discrete distribution, a shared-weight method is proposed to improve the learnt features of the discriminator with the aid of the encoder. Furthermore, we design an interface for the user to draw with basic drawing tools and adjust the number of reconstruction times. The experiments show that the proposed Doodle Master system can successfully beautify the rough doodle or sketch in real-time.\",\n \"Title: Local Binary Pattern Circuit Generator With Adjustable Parameters for Feature Extraction.\\nYear: 2018\\n\\nAbstract: In the field of computer vision, local binary pattern (LBP) is one of the most popular feature extraction method and has been used in many object detection frameworks. To efficiently extract LBP features in high-resolution images, hardware architecture is needed to disperse CPU burden and to improve the entire object detection performance. In this paper, a hardware implementation of an approximate...\",\n \"Title: ORSNet: A Hybrid Neural Network for Official Sports Referee Signal Recognition.\\nYear: 2018\\n\\nAbstract: In this work, we propose a novel sports referee training system based on wearable sensors and a real-time Official Referee Signal (ORS) segmentation/recognition method which can recognize 65 kinds basketball ORSs with the accuracy of 95.3%. A hybrid neural network named ORSNet is designed for recognizing gestures based on IMU signals. The proposed ORSNet involves convolution layers and recurrent layers to learn more representative features and correlations in temporal domain, respectively. A novel loss function and a weight sharing strategy are proposed to learn a more robust ORS recognition model. Moreover, we investigate the influence of applying a semi-supervised network in the proposed ORSNet.\",\n \"Title: A lightweight and efficient system for tracking handheld objects in virtual reality\\nYear: 2018\\n\\nAbstract: While the content of virtual reality (VR) has grown explosively in recent years, the advance of designing user-friendly control interfaces in VR still remains a slow pace. The most commonly used device, such as gamepad or controller, has fixed shape and weight, and thus can not provide realistic haptic feedback when interacting with virtual objects in VR. In this work, we present a novel and lightweight tracking system in the context of manipulating handheld objects in VR. Specifically, our system can effortlessly synchronize the 3D pose of arbitrary handheld objects between the real world and VR in realtime performance. The tracking algorithm is simple, which delicately leverages the power of Leap Motion and IMU sensor to respectively track object's location and orientation. We demonstrate the effectiveness of our system with three VR applications use pencil, ping-pong paddle, and smartphone as control interfaces to provide users more immersive VR experience.\",\n \"Title: Automated tongue diagnosis on the smartphone and its applications.\\nYear: 2019\\n\\nAbstract: •We propose a SVM-based lighting condition estimation method according to color differences of tongue images taken with and without flash on the smartphone under different lighting conditions.•We then train a tongue image color correction matrix for each lighting condition based on the ColorChecker to remove the effect of color distortion. The effects of different model parameters and ColorCheckers on the performance of color correction are also discussed. Finally, in order to demonstrate the potential use of our proposed system, we recruited 246 patients and examined the correlations between the captured tongue features and ALT/ AST.•We found that some tongue features have strong correlation with the AST or ALT, which suggests the possible use of these tongue features captured on a smartphone to provide an early warning of liver diseases.\",\n \"Title: Furniture style compatibility recommendation with cross-class triplet loss.\\nYear: 2019\\n\\nAbstract: Harmonizing the style of all the furniture placed within a constrained space/scene is an important principle for interior design. In this paper, we propose a furniture style compatibility recommendation approach for users to create a harmonic 3D virtual scene based on 2D furniture photos. Most previous works of 3D model style analysis measure the style similarity or compatibility based on predefined geometric features extracted from 3D models. However, “style” is a high-level semantic concept, which is difficult to be described explicitly by hand-crafted geometric features. Moreover, analyzing the style compatibility between two or more furniture belonging to different classes (e.g., table and lamp) is much more challenging since the given furniture may have very distinctive structures or geometric elements. Recently, deep neural network has been claimed to have more powerful ability to mimic the perception of human visual cortex, and therefore we propose to analyze style compatibility between 3D furniture models of different classes based on a Cross-Class Triplet Convolutional Neural Network (CNN). We conducted experiments based on a collected dataset containing 420 textured 3D furniture models. A group of raters were recruited from Amazon Mechanical Turk (AMT) to evaluate the comparative suitability of paired models within the dataset. The experimental results reveal that the proposed furniture style compatibility method based on deep learning performs better than the state-of-the-art method and can be used to efficiently generate harmonic virtual scenes.\",\n \"Title: Training assistant: strengthen your tactical nous with proficient virtual basketball players\\nYear: 2018\\n\\nAbstract: Tactic training plays a crucial role in basketball offensive plays. With the aid of virtual reality, we propose a framework to improve the effectiveness and experience of tactic learning. The framework consists of a tactic input device and a wireless VR interaction system, which allows the user to conveniently input target tactic and practice in a high-fidelity circumstance. By the assistance of our VR training system, the user can vividly experience how the tactics are executed by viewing from the a specific player's viewing direction. Additionally, tactic movement guidance, action hint of how to offense aggressively, and virtual defenders are rendered in our system to make the training more realistic. By using the proposed framework, players can strengthen their tactical nous and improve the efficiency of tactic training.\",\n \"Title: Handwriting Trajectory Reconstruction Using Low-Cost IMU.\\nYear: 2019\\n\\nAbstract: In this paper, we propose a trajectory reconstruction method based on low-cost Inertial Measurement Unit (IMU) in smartphones. The IMU used in our work consists of a three-axis accelerometer and a three-axis gyroscope, which can record information of acceleration and rotation, respectively. Since intrinsic bias and random noise usually cause unreliable IMU signals, filtering methods are utilized t...\",\n \"Title: MultiMedia Modeling - 26th International Conference, MMM 2020, Daejeon, South Korea, January 5-8, 2020, Proceedings, Part I.\\nYear: 2020\\n\\nAbstract: The two-volume set LNCS 11961 and 11962 constitutes the thoroughly refereed proceedings of the 25th International Conference on MultiMedia Modeling, MMM 2020, held in Daejeon, South Korea, in January 2020.Of the 171 submitted full research papers, 40 papers were selected for oral presentation and 46 for poster presentation; 28 special session papers were selected for oral presentation and 8 for poster presentation; in addition, 9 demonstration papers and 6 papers for the Video Browser Showdown 2020 were accepted. The papers of LNCS 11961 are organized in the following topical sections: audio and signal processing; coding and HVS; color processing and art; detection and classification; face; image processing; learning and knowledge representation; video processing; poster papers; the papers of LNCS 11962 are organized in the following topical sections: poster papers; AI-powered 3D vision …\",\n \"Title: MultiMedia Modeling - 26th International Conference, MMM 2020, Daejeon, South Korea, January 5-8, 2020, Proceedings, Part II.\\nYear: 2020\\n\\nAbstract: The two-volume set LNCS 11961 and 11962 constitutes the thoroughly refereed proceedings of the 25th International Conference on MultiMedia Modeling, MMM 2020, held in Daejeon, South Korea, in January 2020. Of the 171 submitted full research papers, 40 papers were selected for oral presentation and 46 for poster presentation; 28 special session papers were selected for oral presentation and 8 for poster presentation; in addition, 9 demonstration papers and 6 papers for the Video Browser Showdown 2020 were accepted. The papers of LNCS 11961 are organized in the following topical sections: audio and signal processing; coding and HVS; color processing and art; detection and classification; face; image processing; learning and knowledge representation; video processing; poster papers; the papers of LNCS 11962 are organized in the following topical sections: poster papers; AI-powered 3D vision; multimedia analytics: perspectives, tools and applications; multimedia datasets for repeatable experimentation; multi-modal affective computing of large-scale multimedia data; multimedia and multimodal analytics in the medical domain and pervasive environments; intelligent multimedia security; demo papers; and VBS papers.\",\n \"Title: STR-GQN - Scene Representation and Rendering for Unknown Cameras Based on Spatial Transformation Routing.\\nYear: 2021\\n\\nAbstract: Geometry-aware modules are widely applied in recent deep learning architectures for scene representation and rendering. However, these modules require intrinsic camera information that might not be obtained accurately. In this paper, we propose a Spatial Transformation Routing (STR) mechanism to model the spatial properties without applying any geometric prior. The STR mechanism treats the spatial transformation as the message passing process, and the relation between the view poses and the routing weights is modeled by an end-to-end trainable neural network. Besides, an Occupancy Concept Mapping (OCM) framework is proposed to provide explainable rationals for scene-fusion processes. We conducted experiments on several datasets and show that the proposed STR mechanism improves the performance of the Generative Query Network (GQN). The visualization results reveal that the routing process can pass the observed information from one location of some view to the associated location in the other view, which demonstrates the advantage of the proposed model in terms of spatial cognition.\",\n \"Title: Reducing Library Characterization Time For Cell-Aware Test While Maintaining Test Quality\\nYear: 2021\\n\\nAbstract: Cell-aware test (CAT) explicitly targets faults caused by defects inside library cells to improve test quality, compared with conventional automatic test pattern generation (ATPG) approaches, which target faults only at the boundaries of library cells. The CAT methodology consists of two stages. Stage 1, based on dedicated analog simulation, library characterization per cell identifies which cell-level test pattern detects which cell-internal defect; this detection information is encoded in a defect detection matrix (DDM). In Stage 2, with the DDMs as inputs, cell-aware ATPG generates chip-level test patterns per circuit design that is build up of interconnected instances of library cells. This paper focuses on Stage 1, library characterization, as both test quality and cost are determined by the set of cell-internal defects identified and simulated in the CAT tool flow. With the aim to achieve the best test quality, we first propose an approach to identify a comprehensive set, referred to as full set, of potential open- and short-defect locations based on cell layout. However, the full set of defects can be large even for a single cell, making the time cost of the defect simulation in Stage 1 unaffordable. Subsequently, to reduce the simulation time, we collapse the full set to a compact set of defects which serves as input of the defect simulation. The full set is stored for the diagnosis and failure analysis. With inspecting the simulation results, we propose a method to verify the test quality based on the compact set of defects and, if necessary, to compensate the test quality to the same level as that based on the full set of defects. For 351 combinational library cells in Cadence's GPDK045 45nm library, we simulate only 5.4% defects from the full set to achieve the same test quality based on the full set of defects. In total, the simulation time, via linear extrapolation per cell, would be reduced by 96.4% compared with the time based on the full set of defects.\",\n \"Title: Semi-supervised Many-to-many Music Timbre Transfer\\nYear: 2021\\n\\nAbstract: ABSTRACTThis work presents a music timbre transfer model that aims to transfer the style of a music clip while preserving the semantic content. Compared to the existing music timbre transfer models, our model can achieve many-to-many timbre transfer between different instruments. The proposed method is based an autoencoder framework, which comprises two pretrained encoders trained in a supervised manner and one decoder trained in an unsupervised manner. To learn more representative features for the encoders, we produced a parallel dataset, called MI-Para, which is synthesized from MIDI files and digital audio workstations (DAW). Both the objective and the subjective evaluation results showed the effectiveness of the proposed framework. To scale up the application scenario, we also demonstrate that our model can achieve style transfer by training in a semi-supervised manner with a smaller parallel dataset.\",\n \"Title: MMArt-ACM'21: International Joint Workshop on Multimedia Artworks Analysis and Attractiveness Computing in Multimedia 2021\\nYear: 2021\\n\\nAbstract: ABSTRACTThe International Joint Workshop on Multimedia Artworks Analysis and Attractiveness Computing in Multimedia (MMArt-ACM) solicits contributions on methodology advancement and novel applications of multimedia artworks and attractiveness computing that emerge in the era of big data and social media. The topics of the accepted papers cover an analytic topic on comic contents understanding to generative topics on image synthesis and conversion. The actual MMArt-ACM'21 Proceedings are available at: https://dl.acm.org/doi/proceedings/10.1145/3460426.\",\n \"Title: Deep Model Style: Cross-Class Style Compatibility For 3d Furniture Within A Scene\\nYear: 2017\\n\\nAbstract: Harmonizing the style of all the furniture placed within a constrained space/scene has been regarded as one of the most important tasks in interior design. Most previous style analysis works measure the style similarity or compatibility of the objects based on predefined geometric features extracted from 3D models. However, style\\\" is a high-level semantic concept, which is difficult to be described explicitly by hand-crafted geometric features. Deep neural network has been claimed to have more powerful ability to mimic the perception of human visual cortex. Therefore, in this work we utilize Triplet Convolutional Neural Network (Triplet CNN) to analyze style compatibility between 3D furniture models of different classes (e.g., a table and a lamp). It should be noted that analyzing the style compatibility between two or more furniture of different classes is quite difficult, as the given furniture may have distinctive structures or geometric elements. We conducted experiments based on a collected dataset containing 420 textured 3D furniture models. A group of raters were recruited from Amazon Mechanical Turk (AMT) to evaluate the comparative suitability of paired models within the dataset. The experimental results reveal that the proposed furniture style compatibility method based on deep learning is better than the state-of-the-art method and can be used for furniture recommendation.\",\n \"Title: Investigating the Affective State of VR HMD User When Watching Videos Displayed in Different Formats\\nYear: 2021\\n\\nAbstract: In recent years, many studies have discussed whether virtual reality (VR) can enhance the sensory experience of the audience via a controllable virtual environment. Most of the researches focus on comparing the difference of perceptual immersion between LCD screen and VR, or the impact on the narrative of the two media. The goal of this study is to investigate the affective state in VR head-mounte...\",\n \"Title: Instant Basketball Defensive Trajectory Generation\\nYear: 2022\\n\\nAbstract: AbstractTactic learning in virtual reality (VR) has been proven to be effective for basketball training. Endowed with the ability of generating virtual defenders in real time according to the movement of virtual offenders controlled by the user, a VR basketball training system can bring more immersive and realistic experiences for the trainee. In this article, an autoregressive generative model for instantly producing basketball defensive trajectory is introduced. We further focus on the issue of preserving the diversity of the generated trajectories. A differentiable sampling mechanism is adopted to learn the continuous Gaussian distribution of player position. Moreover, several heuristic loss functions based on the domain knowledge of basketball are designed to make the generated trajectories assemble real situations in basketball games. We compare the proposed method with the state-of-the-art works in terms of both objective and subjective manners. The objective manner compares the average position, velocity, and acceleration of the generated defensive trajectories with the real ones to evaluate the fidelity of the results. In addition, more high-level aspects such as the empty space for offender and the defensive pressure of the generated trajectory are also considered in the objective evaluation. As for the subjective manner, visual comparison questionnaires on the proposed and other methods are thoroughly conducted. The experimental results show that the proposed method can achieve better performance than previous basketball defensive trajectory generation works in terms of different evaluation metrics.\",\n \"Title: Feasibility Study on Using AI and VR for Decision-Making Training of Basketball Players\\nYear: 2021\\n\\nAbstract: Decision-making plays an essential role in basketball offense. Offensive players must make effective decisions to score a basket in various defensive situations. Virtual reality (VR) has been widely used in the training of athletes to strengthen their ability to make optimal decisions by creating controllable repeatable training scenarios. In this article, an action-aware offensive decision-making...\",\n \"Title: An imitation learning framework for generating multi-modal trajectories from unstructured demonstrations\\nYear: 2022\\n\\nAbstract: The main challenge of the trajectory generation problem is to generate long-term as well as diverse trajectories. Generative Adversarial Imitation Learning (GAIL) is a well-known model-free imitation learning algorithm that can be utilized to generate trajectory data, while vanilla GAIL would fail to capture multi-modal demonstrations. Recent methods propose latent variable models to solve this problem; however, previous works may have a mode missing problem. In this work, we propose a novel method to generate long-term trajectories that are controllable by a continuous latent variable based on GAIL and a conditional Variational Autoencoder (cVAE). We further assume that subsequences of the same trajectory should be encoded to similar locations in the latent space. Therefore, we introduce a contrastive loss in the training of the encoder. In our motion synthesis task, we propose to first construct a low-dimensional motion manifold by using a VAE to reduce the burden of our imitation learning model. Our experimental results show that the proposed model outperforms the state-of-the-art methods and can be applied to motion synthesis.\",\n \"Title: Assist Home Training Table Tennis Skill Acquisition via Immersive Learning and Web Technologies\\nYear: 2022\\n\\nAbstract: Sports applications in Virtual Reality (VR) have become immensely popular for training skill-based sports like table tennis. However, the existing researches do not focus on designing an intuitive system for efficient communication between the trainee and the coach. We developed a VR table tennis training system for table tennis skill acquisition that focuses on helping coaches to convey a trainee's mistake clearly. Our system consists of a VR training system where trainees can learn a skill gradually and a web-based feedback annotative tool for coaches. Trainees can examine their mistakes through a tablet or an immersive VR world.\",\n \"Title: Computer Vision Based Cognition Assessment for Developmental-Behavioral Screening\\nYear: 2022\\n\\nAbstract: Common screening tasks for developmental-behavioral disabilities require human judgement to decide pass/fail on checklists, which possibly causes subjective biases. On the other hand, professional requirements for an assessment build a barrier for the accessibility to such screening tests. Therefore, we applied a combination of computer vision techniques to automatically perform cognition assessment on toddlers. To tackle insufficient data, multi-person scene, and unexpected movements of toddlers, YOLOv5, Mediapipe, LOFTR, and depth prediction model trained from Mannequin Challenge dataset are utilized to accurately focus our detection model on assigned areas to generate better results. We believe that similar concepts could be further extended to other sub-fields in childhood developmental-behavioral screening and improve clinical practice.\",\n \"Title: ScoreActuary: Hoop-Centric Trajectory-Aware Network for Fine-Grained Basketball Shot Analysis\\nYear: 2022\\n\\nAbstract: ABSTRACTWe propose a fine-grained basketball shot analysis system called ScoreActuary to analyze the players' shot events, which can be applied to game analysis, player training, and highlight generation. Given a basketball video as input, our system first detects/segments shot candidates and then analyzes \\\"Shot Type\\\", \\\"Shot Result\\\", and \\\"Ball Status\\\" of each shot candidate in real-time. Our approach is composed of a customized object detector and a trajectory-aware network to learn the information of ball trajectory. Compared to the existing methods that analyze basketball shots, our algorithm can better handle videos with arbitrary camera movements while improving the accuracy. To the best of our knowledge, this work is the first system that can analyze fine-grained shot events accurately in real basketball games with arbitrary camera movements.\",\n \"Title: BetterSight: Immersive Vision Training for Basketball Players\\nYear: 2022\\n\\nAbstract: ABSTRACTVision training is important for athletes and is key to win a sports game. Traditional vision training methods are suitable for sports that focus only on the ball. For basketball, however, players need to observe multiple moving objects (i.e., ball and players) concurrently on a large court. We propose BetterSight, an immersive vision training system for basketball that not only trains the vision of the player but also requires the player to dribble the ball stably, mimicking the situation in a real basketball game. BetterSight is composed of an Interaction Module (IM), a Training Content Generation Module (TCGM), and an Analysis Module (AM). IM allows the trainee to interact with the system more intuitively based on gesture and speech rather than the controller. TCGM simulates the training scenarios based on the training configurations selected by the trainee. AM collects the video sequences capturing the trainee and the trainee's eye movements during the training phase, and then analyzes the trainee's gaze, dribbling movements, and number of dribbles. The analyzed data can be used to evaluate the training effectiveness of using the proposed BetterSight.\",\n \"Title: StimulusLoop: Game-Actuated Mutuality Artwork for Evoking Affective State\\nYear: 2022\\n\\nAbstract: ABSTRACTAs transmission technology has advanced, large-scale media data is delivered to users. However, machines may collect user behavior while users are receiving messages and analyze how to stimulate users' senses to grab more attention. To demonstrate the relationship between machines and users, we propose a game-actuated mutuality artwork, StimulusLoop. We design the visualization to present the users' behavior and affective state and design the game mechanics that one participant throws the dart to change the video watched by the other participant. The interactions between two participants form a game loop, and different kinds of messages passing between the two participants are visualized as mutuality artwork.\",\n \"Title: GetWild: A VR Editing System with AI-Generated 3D Object and Terrain\\nYear: 2022\\n\\nAbstract: ABSTRACT3D environment artists typically use 2D screens and 3D modeling software to achieve their creation. However, creating 3D content using 2D tools is counterintuitive. Moreover, the process would be inefficient for junior artists in the absence of a reference. We develop a system called GetWild, which employs artificial intelligence (AI) models to generate the prototype of 3D objects/terrain and allows users to further edit the generated content in the virtual space. With the aid of AI, the user can capture an image to obtain a rough 3D object model, or start with drawing simple sketches representing the river, the mountain peak and the mountain ridge to create a 3D terrain prototype. Further, the virtual reality (VR) technique is used to provide an immersive design environment and intuitive interaction (such as painting, sculpturing, coloring, and transformation) for users to edit the generated prototypes. Compared with the existing 3D modeling software and systems, the proposed VR editing system with AI-generated 3D objects/terrain provides a more efficient way for the user to create virtual artwork.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":61,"string":"61"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":47,"string":"47"}}},{"rowIdx":48,"cells":{"question_id":{"kind":"string","value":"Javad Lavaei"},"question":{"kind":"string","value":"Generate an abstract for the title \"Decentralized Implementation of Centralized Controllers for Interconnected Systems\" using the following items: centralized controller, decentralized controller, LTI interconnected system, structural initial value observability, decentralization method."},"answer":{"kind":"string","value":"Given a centralized controller associated with a linear time-invariant (LTI) interconnected system, this paper is concerned with designing a parameterized decentralized controller in such a way that the state and input of the system under the obtained decentralized controller can become arbitrarily close to those of the system under the given centralized controller, by tuning the controller's parameters. To this end, a two-level decentralized controller is designed, where the upper level captures the dynamics of the centralized closed-loop system, and the lower level is an observed-based subcontroller designed based on the new notion of structural initial value observability. The proposed method can decentralize every generic centralized controller, provided the interconnected system satisfies very mild conditions."},"correct_answer":{"kind":"string","value":"Given a centralized controller associated with a linear time-invariant (LTI) interconnected system, this paper is concerned with designing a parameterized decentralized controller in such a way that the state and input of the system under the obtained decentralized controller can become arbitrarily close to those of the system under the given centralized controller, by tuning the controller's parameters. To this end, a two-level decentralized controller is designed, where the upper level captures the dynamics of the centralized closed-loop system, and the lower level is an observed-based subcontroller designed based on the new notion of structural initial value observability. The proposed method can decentralize every generic centralized controller, provided the interconnected system satisfies very mild conditions."},"documents":{"kind":"list like","value":["Title: Relationship between power loss and network topology in power systems\nYear: 2010\n\nAbstract: This paper is concerned with studying how the minimum power loss in a power system is related to its network topology. The existing algorithms in the literature all exploit nonlinear, heuristic, or local search algorithms to find the minimum power loss, which make them blind to the network topology. Given certain constraints on power level, bus voltages, etc., a linear-matrix-inequality (LMI) optimization problem is derived, which provides a lower bound on the minimum active loss in the network. The proposed LMI problem has the property that its objective function depends on the loads and its matrix inequality constraint is related to the topology of the power system. This property makes it possible to address many important power problems, such as the optimal network reconfiguration and the optimal placement/sizing of distributed generation units in power systems. Moreover, a condition is provided under which the solution of the given LMI problem is guaranteed to be exactly equal to the minimum power loss. As justified mathematically and verified on IEEE test systems, this condition is expected to hold widely in practice, implying that a practical power loss minimization problem is likely to be solvable using a convex algorithm.","Title: Controllability and observability of uncertain systems: A robust measure\nYear: 2009\n\nAbstract: This paper deals with the class of polynomially uncertain continuous-time linear time-invariant (LTI) systems whose uncertainties belong to a semi-algebraic set. The objective is to determine the minimum of the smallest singular value of the controllability or observability Gramian over the uncertainty region. This provides a quantitative measure for the robust controllability or observability degree of the system. To this end, it is shown that the problem can be recast as a sum-of-squares (SOS) problem. In the special case when the uncertainty region is polytopic, the corresponding SOS formulation can be simplified significantly. One can apply the proposed method to any large-scale interconnected system to identify those inputs and outputs that are more effective in controlling the system. This enables the designer to simplify the control structure by ignoring those inputs and outputs whose contribution to the overall control operation is relatively weak. A numerical example is presented to demonstrate the efficacy of the results.","Title: Solving large-scale linear circuit problems via convex optimization\nYear: 2009\n\nAbstract: A broad class of problems in circuits, electromag- netics, and optics can be expressed as finding some parameters of a linear system with a specific type. This paper is concerned with studying this type of circuit using the available control techniques. It is shown that the underlying problem can be recast as a rank minimization problem that is NP-hard in general. In order to circumvent this difficulty, the circuit problem is slightly modified so that the resulting optimization becomes convex. This interesting result is achieved at the cost of complicating the structure of the circuit, which introduces a trade-off between the design simplicity and the implementation complexity. When it is strictly required to solve the original circuit problem, the elegant structure of the proposed rank minimization problem allows to employ a celebrated heuristic method to solve it efficiently. I. INTRODUCTION","Title: Quantized Consensus by Means of Gossip Algorithm.\nYear: 2012\n\nAbstract: This paper deals with the distributed averaging problem over a connected network of agents, subject to a quantization constraint. It is assumed that at each time update, only a pair of agents can update their own states in terms of the quantized data being exchanged. The agents are also required to communicate with one another in a stochastic fashion. It is shown that a quantized consensus is reached for an arbitrary quantizer by means of the stochastic gossip algorithm proposed in a recent paper. The expected value of the time at which a quantized consensus is reached is lower and upper bounded in terms of the topology of the graph for a uniform quantizer. In particular, it is shown that these bounds are related to the principal submatrices of the weighted Laplacian matrix. A convex optimization is also proposed to determine a set of probabilities used to pick a pair of agents that leads to a fast convergence of the gossip algorithm.","Title: Robust Stability of LTI Systems Over Semialgebraic Sets Using Sum-of-Squares Matrix Polynomials\nYear: 2008\n\nAbstract: This paper deals with the robust stability of discrete-time linear time-invariant systems with parametric uncertainties belonging to a semialgebraic set. It is asserted that the robust stability of any system over any semialgebraic set (satisfying a mild condition) is equivalent to solvability of a semidefinite programming (SDP) problem, which can be handled using the available software tools. The particular case of a semialgebraic set associated with a polytope is then investigated, and a computationally appealing method is proposed to attain the SDP problem by means of a sampling technique, introduced recently in the literature. Furthermore, it is shown that the current result encompasses the ones presented in some of the recent works. The efficacy of the proposed method is demonstrated through some illustrative examples, and the results are compared to some of the existing methods.","Title: Robust controllability and observability degrees of polynomially uncertain systems\nYear: 2009\n\nAbstract: This paper deals with the class of polynomially uncertain continuous-time linear time-invariant (LTI) systems whose uncertainties belong to a semi-algebraic set. The objective is to determine the minimum of the smallest singular value of the controllability or observability Gramian over the uncertainty region. This provides a quantitative measure for the robust controllability or observability degree of the system. To this end, it is shown that the problem can be recast as a sum-of-squares (SOS) problem. In the special case when the uncertainty region is polytopic, the corresponding SOS formulation can be simplified significantly. One can apply the proposed method to any large-scale interconnected system in order to identify those inputs and outputs that are more effective in controlling the system, in a robust manner. This enables the designer to simplify the control structure by ignoring those inputs and outputs whose contribution to the overall control operation is relatively weak. A numerical example is presented to demonstrate the efficacy of the results.","Title: Stabilization of decentralized control systems by means of periodic feedback\nYear: 2008\n\nAbstract: This paper deals with structurally constrained periodic control design for interconnected systems. It is assumed that the system is linear time-invariant (LTI), observable and controllable, and that its modes are distinct and nonzero. It is shown that the notions of a quotient fixed mode (QFM) and a structured decentralized fixed mode (SDFM) are equivalent for this class of systems. Then, it is proved that if the system is decentrally stabilizable, then one candidate for the decentralized stabilizing controller is a time-varying one consisting of a decentralized LTI discrete-time compensator and a zero-order hold. More specifically, the non-quotient fixed modes of the system will be eliminated via sampling for almost all sampling periods, while any QFM will still remain a fixed mode. The results obtained are ultimately extended to the case when the system has some repeated modes, none of which is a DFM.","Title: Convexification of optimal power flow problem by means of phase shifters\nYear: 2013\n\nAbstract: This paper is concerned with the convexification of the optimal power flow (OPF) problem. We have previously shown that this highly nonconvex problem can be solved efficiently via a convex relaxation after two approximations: (i) adding a sufficient number of virtual phase shifters to the network topology, and (ii) relaxing the power balance equations to inequality constraints. The objective of the present paper is to first provide a better understanding of the implications of Approximation (i) and then remove Approximation (ii). To this end, we investigate the effect of virtual phase shifters on the feasible set of OPF by thoroughly examining a cyclic system. We then show that OPF can be convexified under only Approximation (i), provided some mild assumptions are satisfied. Although this paper mainly focuses on OPF, the results developed here can be applied to several OPF-based emerging optimization problems for future electrical grids.","Title: A graph-theoretic method to find decentralized fixed modes of LTI systems\nYear: 2007\n\nAbstract: This paper deals with the decentralized pole assignability of interconnected systems by means of linear time-invariant (LTI) controllers. A simple graph-theoretic approach is proposed to identify the distinct decentralized fixed modes (DFMs) of the system, i.e., the unrepeated modes which cannot be moved by means of a LTI decentralized controller. The state-space representation of the system is transformed to the decoupled form using a proper change of coordinates. For any unrepeated mode, a matrix is then computed which resembles the transfer function matrix of the system at some point in the complex plane. A bipartite graph is constructed accordingly in terms of the computed matrix. Now, the problem of verifying if this mode is a DFM of the system reduces to checking if the constructed graph has a complete bipartite subgraph with a certain property. The sole restriction of this work is that it is only capable of identifying the distinct DFMs of a system. However, it is axiomatic that most of the modes of the real-world systems are normally distinct. The primary advantage of the present paper is its simplicity, compared to the existing ones which often require evaluating the rank of several matrices.","Title: Robust Stabilizability Verification of Polynomially Uncertain LTI Systems\nYear: 2007\n\nAbstract: This paper investigates the stabilizability of uncertain linear time-invariant (LTI) systems via structurally constrained controllers. First, an LTI uncertain system is considered whose state-space matrices depend polynomially on the uncertainty vector, defined over some region. It is shown that if the system is stabilizable by a structurally constrained controller in one point belonging to the region, then it is stabilizable by a controller with the same structure in all points belonging to the region, except for those located on an algebraic variety. Thus, if a system is stabilizable via a constrained controller at the nominal point, then it is almost always stabilizable at any operating point around the nominal model. It is also shown how this algebraic variety (or the dominant subvariety of it) can be computed efficiently. The results obtained in this paper encompass a broad range of the existing results in the literature on robust stability of the LTI systems, in addition to new ones.","Title: Simultaneous LQ control of a set of LTI systems using constrained generalized sampled-data hold functions\nYear: 2007\n\nAbstract: In this paper, sampled-data control of a set of continuous-time LTI systems is considered. It is assumed that a predefined guaranteed continuous-time quadratic cost function, which is, in fact, the sum of the performance indices for all systems, is given. The main objective here is to design a decentralized periodic output feedback controller with a prespecified form, e.g., polynomial, piecewise constant, exponential, etc., which minimizes the above mentioned guaranteed cost function. This problem is first formulated as a set of matrix inequalities, and then by using a well-known technique, it is reformulated as a LMI problem. The set of linear matrix inequalities obtained provides necessary and sufficient conditions for the existence of a decentralized optimal simultaneous stabilizing controller with the prespecified form (rather than a general form). Moreover, an algorithm is presented to solve the resultant LMI problem. Finally, the efficiency of the proposed method is demonstrated in two numerical examples.","Title: Optimal decentralized control problem as a rank-constrained optimization.\nYear: 2013\n\nAbstract: This paper is concerned with the long-standing optimal decentralized control (ODC) problem. The objective is to design a fixed-order decentralized controller for a discretetime system to minimize a given finite-time cost function subject to norm constraints on the input and output of the system. We cast this NP-hard problem as a quadratically-constrained quadratic program, and then reformulate it as a rank-constrained optimization. The reformulated problem is a semidefinite program (SDP) after removing its rank-1 constraint. Whenever the SDP relaxation has a rank-1 solution, a globally optimal decentralized controller can be recovered from this solution. This paper studies the rank of the minimum-rank solution of the SDP relaxation since this number may provide rich information about the level of the approximation needed to make the ODC problem tractable. Using our recently developed notion of \"nonlinear optimization over graph\", we propose a methodology to compute the rank of the minimum-rank solution of the SDP relaxation. In particular, we show that in the case where the unknown decentralized controller being sought needs to be static with a diagonal matrix gain, this rank is upper bounded by 4. Since the upper bound is close to 1 and does not depend on the order of the system, the ODC problem may not be as hard as it is thought to be. This paper also proposes a penalized SDP relaxation to heuristically enforce the few unwanted nonzero eigenvalues of the solution to diminish.","Title: Performance improvement of robust controllers for polynomially uncertain systems\nYear: 2010\n\nAbstract: This paper is concerned with the high-performance robust control of discrete-time linear time-invariant (LTI) systems with semi-algebraic uncertainty regions. It is assumed that a robustly stabilizing static controller is given whose gain depends polynomially on the uncertain variables. The problem of tuning this parameter-dependent gain with respect to a prescribed quadratic cost function is formulated as a sum-of-squares (SOS) optimization. This method leads to a near-optimal controller whose performance is better than that of the initial controller. It is shown that the results derived in the present work encompass the ones obtained in a recent paper. The efficacy of the results is elucidated by an example.","Title: A Model Predictive Decentralized Control Scheme With Reduced Communication Requirement for Spacecraft Formation\nYear: 2008\n\nAbstract: This brief investigates the control problem for a number of cooperative spacecraft with communication constraints. It is assumed that a set of cooperative local controllers corresponding to the individual spacecraft is given which satisfies the desired objectives of the formation. It is to be noted that due to the information exchange between the local controllers, the overall control structure can be considered centralized in general. However, communication in flight formation is expensive. Thus, it is desired to have some form of decentralization in control structure, which has a lower communication requirement. This decentralized controller consists of local estimators inherently, so that each local controller estimates the state of the whole formation. Necessary and sufficient conditions for the stability of the formation under the proposed decentralized controller are obtained. It is shown that the decentralized control system, if stable, behaves almost the same as its centralized counterpart. Moreover, robustness of the decentralized controller is studied and compared to that of the corresponding centralized controller. It is finally shown that the proposed decentralized controller comprises most of the features of its centralized counterpart. The efficacy of the proposed method is demonstrated through simulations.","Title: Overlapping control design for multi-channel systems\nYear: 2009\n\nAbstract: This paper deals with the decentralized overlapping control of interconnected systems. The notion of a quotient overlapping fixed mode (QOFM) is first introduced and it is shown that a mode of an interconnected linear time-invariant system can be shifted by means of a general decentralized overlapping controller if and only if it is not a QOFM. It is then asserted that any interconnected system with no unstable QOFM can be stabilized by using an appropriate finite-dimensional linear time-varying controller. It is also shown how the existing results aiming at designing a decentralized controller of a certain type such as generalized sampled-data hold function, finite-dimensional linear time-varying, and sampled-data can be utilized to design a decentralized overlapping controller of a desired form, in order to achieve any design specification. The efficacy of the results is elucidated through two numerical examples.","Title: Message Passing for Dynamic Network Energy Management\nYear: 2012\n\nAbstract: We consider a network of devices, such as generators, fixed loads, deferrable loads, and storage devices, each with its own dynamic constraints and objective, connected by lossy capacitated lines. The problem is to minimize the total network objective subject to the device and line constraints, over a given time horizon. This is a large optimization problem, with variables for consumption or generation in each time period for each device. In this paper we develop a decentralized method for solving this problem. The method is iterative: At each step, each device exchanges simple messages with its neighbors in the network and then solves its own optimization problem, minimizing its own objective function, augmented by a term determined by the messages it has received. We show that this message passing method converges to a solution when the device objective and constraints are convex. The method is completely decentralized, and needs no global coordination other than synchronizing iterations; the problems to be solved by each device can typically be solved extremely efficiently and in parallel. The method is fast enough that even a serial implementation can solve substantial problems in reasonable time frames. We report results for several numerical experiments, demonstrating the method's speed and scaling, including the solution of a problem instance with over 30 million variables in 52 minutes for a serial implementation; with decentralized computing, the solve time would be less than one second.","Title: Convexification of Generalized Network Flow problem with application to power systems\nYear: 2013\n\nAbstract: This paper is concerned with the minimum-cost flow problem over an arbitrary flow network. In this problem, each node is associated with some possibly unknown injection, each line has two unknown flows at its ends related to each other via a nonlinear function, and all injections and flows need to satisfy certain box constraints. This problem, named generalized network flow (GNF), is highly non-convex due to its nonlinear equality constraints. Under the practical assumption of monotonicity and convexity of the flow and cost functions, a convex relaxation is proposed, which always finds the optimal injections. This relaxation may fail to find optimal flows because the mapping from injections to flows might lead to an exponential number of solutions. However, once optimal injections are found in polynomial time, other techniques can be used to find a feasible set of flows corresponding to the injections. A primary application of this work is in optimization over power networks. Recent work on the optimal power flow (OPF) problem has shown that this non-convex problem can be solved efficiently using semidefinite programming (SDP) after two approximations: relaxing angle constraints (by adding virtual phase shifters) and relaxing power balance equations to inequality constraints. The results of this work prove two facts for the OPF problem: (i) the second approximation (on balance equations) is not needed in practice under a very mild angle assumption, and (ii) if the SDP relaxation fails to find a rank-one solution, the optimal injections (and not flows) may still be recovered from an undesirable high-rank solution.","Title: On quantized consensus by means of gossip algorithm: part ii: convergence time\nYear: 2009\n\nAbstract: This paper deals with the distributed averaging problem over a connected network of agents, subject to a quantization constraint. It is assumed that at each time update, only a pair of agents can update their own numbers in terms of the quantized data being exchanged. The agents are also required to communicate with one another in a stochastic fashion. In the first part of the paper, it was shown that the quantized consensus is reached by means of a stochastic gossip algorithm proposed in a recent paper, for any arbitrary quantization. The current part of the paper considers the expected value of the time at which the quantized consensus is reached. This quantity (corresponding to the worst case) is lower and upper bounded in terms of the topology of the graph, for uniform quantization. In particular, it is shown that the upper bound is related to the principal minors of the weighted Laplacian matrix. A convex optimization is also proposed to determine the set of probabilities (used to pick a pair of agents) which leads to the fast convergence of the gossip algorithm.","Title: Control of continuous-time LTI systems by means of structurally constrained controllers\nYear: 2008\n\nAbstract: This paper deals with the characterization of the fixed modes of multi-channel systems with respect to linear time-invariant (LTI) structurally constrained controllers. Fixed modes can be found numerically for any LTI system with respect to any given control structure, using a random number generator. The existing analytical methods, however, are not capable of characterizing the fixed modes in the most general case of non-strictly proper systems with non-block diagonal (i.e., overlapping) control structure, efficiently. The notion of a decentralized overlapping fixed mode (DOFM) is introduced in this paper to address the above problem in the most general case. To this end, the knowledge of the overlapping control structure is translated into a bipartite graph, whose vertices correspond to the input and output vectors of various control channels. An efficient technique is applied to the obtained graph to identify the DOFMs of the system. It is to be noted that a system is stabilizable via an appropriate LTI decentralized overlapping controller if and only if it does not have any unstable DOFM. Moreover, it is shown how those modes which are not DOFMs can be placed freely in the complex plane using a proper LTI decentralized overlapping controller. The efficacy of this work is demonstrated through an example.","Title: Convex Relaxation for Optimal Power Flow Problem: Mesh Networks\nYear: 2013\n\nAbstract: This paper is concerned with the optimal power flow (OPF) problem. We have recently shown that a convex relaxation based on semidefinite programming (SDP) is able to find a global solution of OPF for IEEE benchmark systems, and moreover this technique is guaranteed to work over acyclic (distribution) networks. The present work studies the potential of the SDP relaxation for OPF over mesh (transmission) networks. First, we consider a simple class of cyclic systems, namely weakly-cyclic networks with cycles of size 3. We show that the success of the SDP relaxation depends on how the line capacities are modeled mathematically. More precisely, the SDP relaxation is proven to succeed if the capacity of each line is modeled in terms of bus voltage difference, as opposed to line active power, apparent power or angle difference. This result elucidates the role of the problem formulation. Our second contribution is to relate the rank of the minimum-rank solution of the SDP relaxation to the network topology. The goal is to understand how the computational complexity of OPF is related to the underlying topology of the power network. To this end, an upper bound is derived on the rank of the SDP solution, which is expected to be small in practice. A penalization method is then applied to the SDP relaxation to enforce the rank of its solution to become 1, leading to a near-optimal solution for OPF with a guaranteed optimality degree. The remarkable performance of this technique is demonstrated on IEEE systems with more than 7000 different cost functions.","Title: Dynamic Network Energy Management via Proximal Message Passing\nYear: 2014\n\nAbstract: We consider a network of devices, such as generators, fixed loads, deferrable loads, and storage devices, each with its owndynamic constraints and objective, connected by AC and DC lines. The problem is to minimize the total network objective subject tothe device and line constraints, over a given time horizon. This is a large optimization problem, with variables for consumptionor generation for each device, power flow for each line, and voltage phase angles at AC buses, in each time period. In this paperwe develop a decentralized method for solving this problem called proximal message passing. The method is iterative: At each step,each device exchanges simple messages with its neighbors in the network and then solves its own optimization problem, minimizing itsown objective function, augmented by a term determined by the messages it has received. We show that this message passing methodconverges to a solution when the device objective and constraints are convex. The method is completely decentralized, and needs noglobal coordination other than synchronizing iterations; the problems to be solved by each device can typically be solved extremelyefficiently and in parallel. The method is fast enough that even a serial implementation can solve substantial problems inreasonable time frames. We report results for several numerical experiments, demonstrating the method's speed and scaling,including the solution of a problem instance with over 10 million variables in under 50 minutes for a serial implementation;with decentralized computing, the solve time would be less than one second.","Title: Exactness of Semidefinite Relaxations for Nonlinear Optimization Problems with Underlying Graph Structure.\nYear: 2014\n\nAbstract: This work is concerned with finding a global optimization technique for a broad class of nonlinear optimization problems, including quadratic and polynomial optimization problems. The main objective of this paper is to investigate how the (hidden) structure of a given real/complex-valued optimization problem makes it easy to solve. To this end, three conic relaxations are proposed. Necessary and sufficient conditions are derived for the exactness of each of these relaxations, and it is shown that these conditions are satisfied if the optimization problem is highly structured. More precisely, the structure of the optimization problem is mapped into a generalized weighted graph, where each edge is associated with a weight set extracted from the coefficients of the optimization problem. In the real-valued case, it is shown that the relaxations are all exact if each weight set is sign definite and in addition a condition is satisfied for each cycle of the graph. It is also proved that if some of these conditions are violated, the relaxations still provide a low-rank solution for weakly cyclic graphs. In the complex-valued case, the notion of \"sign definite complex sets\" is introduced for complex weight sets. It is then shown that the relaxations are exact if each weight set is sign definite (with respect to complex numbers) and the graph is acyclic. Three other structural properties are derived for the generalized weighted graph in the complex case, each of which guarantees the exactness of some of the proposed relaxations. This result is also generalized to graphs that can be decomposed as a union of edge-disjoint subgraphs, where each subgraph has certain structural properties. As an application, it is proved that a relatively large class of real and complex optimization problems over power networks are polynomial-time solvable (with an arbitrary accuracy) due to the passivity of transmission lines and transformers.","Title: Convex relaxation for optimal distributed control problem.\nYear: 2014\n\nAbstract: This paper is concerned with the optimal distributed control (ODC) problem for linear discrete-time deterministic and stochastic systems. The objective is to design a static distributed controller with a prespecified structure that is globally optimal with respect to a quadratic cost functional. It is shown that this NP-hard problem has a quadratic formulation, which can be relaxed to a semidefinite program (SDP). If the SDP relaxation has a rank-1 solution, a globally optimal distributed controller can be recovered from this solution. By utilizing the notion of treewidth, it is proved that the nonlinearity of the ODC problem appears in such a sparse way that an SDP relaxation of this problem has a matrix solution with rank at most 3. Since the proposed SDP relaxation is computationally expensive for a large-scale system, a computationally cheap SDP relaxation is also developed with the property that its objective function indirectly penalizes the rank of the SDP solution. Various techniques are proposed to approximate a low-rank SDP solution with a rank-1 matrix, leading to near globally optimal controllers together with a bound on the optimality degree of each controller. The above results are developed for both finite-horizon and infinite-horizon ODC problems. The SDP relaxations developed in this work are exact for the design of a centralized controller, hence serving as an alternative for solving Riccati equations. The efficacy of the proposed SDP relaxations is elucidated through a case study on the distributed frequency control of power systems.","Title: Graph-theoretic algorithms for polynomial optimization problems\nYear: 2014\n\nAbstract: The objective of this tutorial paper is to study a general polynomial optimization problem using a semidefinite programming (SDP) relaxation. The first goal is to show how the underlying structure and sparsity of an optimization problem affect its computational complexity. Graph-theoretic algorithms are presented to address this problem based on the notions of low-rank optimization and matrix completion. By building on this result, it is then shown that every polynomial optimization problem admits a sparse representation whose SDP relaxation has a rank 1 or 2 solution. The implications of these results are discussed in details and their applications in decentralized control and power systems are also studied.","Title: Low-rank solutions of matrix inequalities with applications to polynomial optimization and matrix completion problems\nYear: 2014\n\nAbstract: This paper is concerned with the problem of finding a low-rank solution of an arbitrary sparse linear matrix inequality (LMI). To this end, we map the sparsity of the LMI problem into a graph. We develop a theory relating the rank of the minimum-rank solution of the LMI problem to the sparsity of its underlying graph. Furthermore, we propose two graph-theoretic convex programs to obtain a low-rank solution. The first convex optimization needs a tree decomposition of the sparsity graph. The second one does not rely on any computationally-expensive graph analysis and is always polynomial-time solvable. The results of this work can be readily applied to three separate problems of minimum-rank matrix completion, conic relaxation for polynomial optimization, and affine rank minimization. The results are finally illustrated on two applications of optimal distributed control and nonlinear optimization for electrical networks.","Title: LQ robust controllers for polynomially uncertain systems\nYear: 2008\n\nAbstract: This paper is concerned with the LQ optimal robust control of discrete-time LTI systems with uncertainties belonging to a semi-algebraic set. Given a prescribed cost function, the problem of designing a gain-scheduled static controller, whose gain depends polynomially on the uncertain parameters is formulated as a SOS problem. This indeed requires solving two hierarchies of SDP problems, which may in turn introduce high computational burden, and hence complicate the optimal robust controller design. To bypass this barrier, an alternative approach is developed which is much less involved, at the cost of obtaining a near-optimal controller (as opposed to an optimal one). The efficacy of this work is elucidated in two numerical examples.","Title: Complexity of checking the existence of a stabilizing decentralized controller\nYear: 2009\n\nAbstract: Given an interconnected system, this paper is concerned with the time complexity of verifying if any given unrepeated mode of the system is a decentralized fixed mode (DFM). It is shown that checking the decentralized fixedness of any distinct mode is tantamount to testing the strong connectivity of a digraph formed based on the system. It is subsequently proved that the time complexity of this decision problem using the proposed approach is the same as the complexity of matrix multiplication. This work concludes that the identification of distinct decentralized fixed modes (by means of a deterministic algorithm, rather than a randomized one) is computationally very easy, although the existing algorithms for solving this problem would wrongly imply that it is cumbersome. This paper provides not only a complexity analysis, but also an efficient algorithm for tackling the underlying problem.","Title: On quantized consensus by means of gossip algorithm - Part I: Convergence proof\nYear: 2009\n\nAbstract: This paper is concerned with the distributed averaging problem subject to a quantization constraint. Given a group of agents associated with scalar numbers, it is assumed that each pair of agents can communicate with a prescribed probability, and that the data being exchanged between them is quantized. In this part of the paper, it is proved that the stochastic gossip algorithm proposed in a recent paper leads to reaching the quantized consensus. Some important steady-state properties of the system (after reaching the consensus) are also derived. The results developed here hold true for any arbitrary quantization, provided that the tuning parameter of the gossip algorithm is chosen properly. The expected value of the convergence time is lower and upper bounded in the second part of the paper.","Title: Pole Assignment With Improved Control Performance by Means of Periodic Feedback\nYear: 2010\n\nAbstract: This technical note is concerned with the pole placement of continuous-time linear time-invariant (LTI) systems by means of LQ suboptimal periodic feedback. It is well-known that there exist infinitely many generalized sampled-data hold functions (GSHF) for any controllable LTI system to place the modes of its discrete-time equivalent model at prescribed locations. Among all such GSHFs, this technical note aims to find the one which also minimizes a given LQ performance index. To this end, the GSHF being sought is written as the sum of a particular GSHF and a homogeneous one. The particular GSHF can be readily obtained using the conventional pole-placement techniques. The homogeneous GSHF, on the other hand, is expressed as a linear combination of a finite number of functions such as polynomials, sinusoidals, etc. The problem of finding the optimal coefficients of this linear combination is then formulated as a linear matrix inequality (LMI) optimization. The procedure is illustrated by a numerical example.","Title: Geometry of power flows in tree networks\nYear: 2012\n\nAbstract: We investigate the problem of power flow and its relationship to optimization in tree networks. We show that due to the tree topology of the network, the general optimal power flow problem simplifies greatly. Our approach is to look at the injection region of the power network. The injection region is simply the set of all vectors of bus power injections that satisfy the network and operation constraints. The geometrical object of interest is the set of Pareto-optimal points of the injection region, since they are the solutions to the minimization of increasing functions. We view the injection region as a linear transformation of the higher dimensional power flow region, which is the set of all feasible power flows, one for each direction of each line. We show that if the voltage magnitudes are fixed, then the injection region becomes a product of two-bus power flow regions, one for each line in the network. Using this decomposition, we show that under the practical condition that the angle difference across each line is not too large, the set of Pareto-optimal points of the injection region remains unchanged by taking the convex hull. Therefore, the optimal power flow problem can be convexified and efficiently solved. This result improves upon earlier works since it does not make any assumptions about the active bus power constraints. We also obtain some partial results for the variable voltage magnitude case.","Title: Solving Large-Scale Hybrid Circuit-Antenna Problems\nYear: 2011\n\nAbstract: Motivated by different applications in circuits, electromagnetics, and optics, this paper is concerned with the synthesis of a particular type of linear circuit, where the circuit is associated with a control unit. The objective is to design a controller for this control unit such that certain specifications on the parameters of the circuit are satisfied. It is shown that designing a control unit in the form of a switching network is an NP-complete problem that can be formulated as a rank-minimization problem. It is then proven that the underlying design problem can be cast as a semidefinite optimization if a passive network is designed instead of a switching network. Since the implementation of a passive network may need too many components, the design of a decoupled (sparse) passive network is subsequently studied. This paper introduces a tradeoff between design simplicity and implementation complexity for an important class of linear circuits. The superiority of the developed techniques is demonstrated by different simulations. In particular, for the first time in the literature, a wavelength-size passive antenna is designed, which has an excellent beamforming capability and which can concurrently make a null in at least eight directions.","Title: Passively Controllable Smart Antennas\nYear: 2010\n\nAbstract: We recently introduced passively controllable smart (PCS) antenna systems for efficient wireless transmission, with direct applications in wireless sensor networks. A PCS antenna system is accompanied by a tunable passive controller whose adjustment at every signal transmission generates a specific radiation pattern. To reduce co-channel interference and optimize the transmitted power, this antenna can be programmed to transmit data in a desired direction in such a way that no signal is transmitted (to the far field) at pre-specified undesired directions. The controller of a PCS antenna was assumed to be centralized in our previous work, which was an impediment to its implementation. In this work, we study the design of PCS antenna systems under decentralized controllers, which are both practically implementable and cost efficient. The PCS antenna proposed here is made of one active element and its programming needs solving second-order-cone optimizations. These properties differentiate a PCS antenna from the existing smart antennas, and make it possible to implement a PCS antenna on a small-sized, low-power silicon chip.","Title: Synthesis of embedded control systems with high sampling frequencies\nYear: 2010\n\nAbstract: Motivated by current technological advances in the design of real-time embedded systems, this work deals with the digital control of a continuous-time linear time-invariant (LTI) system whose output can be sampled at a high frequency. Since a typical sampled-data controller operating at a high sampling frequency needs heavy (high-precision) computation to alleviate its sensitivity to measurement and computational errors, the objective is to design a robust hybrid controller for high-frequency applications with limited computational power. To this end, we exploit our recent results on delay-based controller design and propose a digital-control scheme that can implement every continuous-time stabilizing (LTI) controller. This robust hybrid controller, which consists of an ideal sampler, a digital controller, a number of modified second-order holds and possibly a unity feedback, can operate at arbitrarily high sampling frequencies without requiring expensive, high-precision computation. We also discuss how to find a continuous-time LTI controller satisfying prescribed design specifications so that its corresponding digital controller requires the least processing time.","Title: Congestion control algorithms from optimal control perspective\nYear: 2009\n\nAbstract: This paper is concerned with understanding the connection between the existing Internet congestion control al- gorithms and the optimal control theory. The available resource allocation controllers are mainly devised to derive the state of the system to a desired equilibrium point and, therefore, they are oblivious to the transient behavior of the closed-loop system. This work aims to investigate what dynamical functions the existing algorithms maximize (minimize). In particular, it is shown that there exist meaningful cost functionals whose minimization leads to the celebrated primal and dual congestion algorithms. An implication of this result is that a real network problem may be solved by regarding it as an optimal control problem on which some practical constraints, such as a real- time link capacity constraint, are imposed.","Title: Quantized consensus via adaptive stochastic gossip algorithm\nYear: 2009\n\nAbstract: This paper is concerned with the distributed averaging problem over a given undirected graph. To enable every vertex to compute the average of the initial numbers sitting on the vertices of the graph, the policy is to pick an edge at random and update the values on its ending vertices based on some rules, but only in terms of the quantized data being exchanged between them. Our recent paper showed that the quantized consensus is reached under a simple updating protocol which deploys a fixed tuning factor. The current paper allows the tuning factor to be time-dependent in order to achieve two goals. First, this makes it possible to study the numerical stability of the protocol with a fixed tuning factor under a small perturbation of this parameter. Furthermore, exploiting a time-varying tuning factor facilitates the implementation of the consensus protocol and pushes the steady state of the system towards an equilibrium point, as opposed to making it oscillatory. The current paper is an important extension of our recent work, which generalizes a finite-dimensional problem to an infinite-dimensional one that is more challenging in nature.","Title: A new decentralization technique for interconnected systems\nYear: 2009\n\nAbstract: This paper deals with LTI interconnected systems whose subsystems have coupled dynamics. The objective is to decentralize a given centralized controller satisfying some prescribed design specifications. More precisely, a parameterized decentralized controller is to be designed such that the state and the input of the system under the obtained decentralized controller can become arbitrarily close to those of the system under the given centralized controller, by tuning its free parameters. To this end, a two-level decentralized controller is designed, where the top level captures the dynamics of the centralized control system. The notion of structural initial value observability is introduced to design the bottom level of the decentralized controller. This method can decentralize every generic centralized controller, provided the interconnected system satisfies very mild conditions.","Title: Utility Functionals Associated With Available Congestion Control Algorithms\nYear: 2010\n\nAbstract: This paper is concerned with understanding the connection between the existing Internet congestion control algorithms and the optimal control theory. The available resource allocation controllers are mainly devised to derive the state of the system to a desired equilibrium point and, therefore, they are oblivious to the transient behavior of the closed-loop system. To take into account the real-time performance of the system, rather than merely its steady-state performance, the congestion control problem should be solved by maximizing a proper utility functional as opposed to a utility function. For this reason, this work aims to investigate what utility functionals the existing congestion control algorithms maximize. In particular, it is shown that there exist meaningful utility functionals whose maximization leads to the celebrated primal, dual and primal/dual algorithms. An implication of this result is that a real network problem may be solved by regarding it as an optimal control problem on which some practical constraints, such as a real-time link capacity constraint, are imposed.","Title: Optimal Periodic Feedback Design For Continuous-Time Lti Systems With Constrained Control Structure\nYear: 2007\n\nAbstract: This paper aims to design a high-performance controller with any predefined structure for continuous-time LTI systems. The control law employed is the generalized sampled-data hold function (GSHF), which can have any special form, e. g. polynomial, exponential, piecewise constant, etc. The GSHF is first written as a linear combination of a set of basis functions obtained in accordance with its desired form and structure. The objective is to find the coefficients of this linear combination, such that a prespecified linear-quadratic performance index is minimized. A necessary and sufficient condition for the existence of such GSHF is first obtained in the form of matrix inequality, which can be solved by using the existing methods to obtain a set of stabilizing initial values for the coefficients or to conclude the non-existence of such structurally constrained GSHF. An efficient algorithm is then presented to compute the optimal coefficients from their initial values, so that the performance index is minimized. The paper utilizes the latest developments in the area of sum-of-square polynomials. The effectiveness of the proposed method is demonstrated in two numerical examples.","Title: Lq Suboptimal Decentralised Controllers With Disturbance Rejection Property For Hierarchical Systems\nYear: 2008\n\nAbstract: This article is concerned with decentralised output regulation of hierarchical systems subject to input and output disturbances. It is assumed that the disturbance can be represented as the output of an autonomous linear time invariant (LTI) system with an unknown initial state. The primary objective is to design a decentralised controller with the property that not only does it reject the degrading effect of the disturbance on the output (to achieve a satisfactory steady-state performance), it also results in a small linear quadratic (LQ) cost function (implying a good transient behaviour). To this end, the underlying problem is treated in two phases. In the first step, a number of modified systems are defined in terms of the original system. The problem of designing an LQ centralised controller which stabilises all the modified systems and rejects the disturbance in the original system is considered, and it is shown that this centralised controller can be found efficiently by solving a linear matrix inequality (LMI) problem. In the second step, a method recently presented in the literature is exploited to decentralise the designed centralised controller. It is shown that the obtained controller satisfies the prescribed design specifications including disturbance rejection. Finally, in a more pragmatic context, the system is assumed to be subject to input delay, and a robustness analysis is carried out accordingly. Simulation results elucidate the efficacy of the proposed control law.","Title: High-Performance Decentralized Control Design For General Interconnected Systems With Applications In Cooperative Control\nYear: 2007\n\nAbstract: This paper deals with the decentralized control of an interconnected system, where each subsystem has models of all other subsystems ( subject to uncertainty). A decentralized controller is constructed based on a reference centralized controller. It is shown that when a priori knowledge of each subsystem about the other subsystems' models is exact, then the decentralized closed-loop system can perform exactly the same as its centralized counterpart. An easy-to-check necessary and sufficient condition for the internal stability of the decentralized closed-loop system is obtained. Moreover, the stability of the closed-loop system in the presence of the perturbation in the parameters of the system is investigated, and it is shown that the decentralized control system is probably more robust than its centralized counterpart. A proper cost function is then defined to evaluate the closeness of the decentralized closed-loop system to the corresponding centralized control system. This enables the designer to obtain the maximum allowable standard deviation for the modelling errors of the subsystems to achieve a satisfactorily small relative performance deviation with a sufficiently high probability. Finally, the proposed method is exploited to design a near-optimal decentralized control law with respect to a quadratic cost function, whose performance can, under certain conditions, be equal to the minimum achievable performance index corresponding to the centralized LQR control law. The effectiveness of the proposed method is demonstrated in three numerical examples.","Title: The Theory Of Complex Systems With Applications To Smart Grid Operations\nYear: 2016\n\nAbstract: The papers in this special section focus on complex systems within current smart grid operations. The existing power grids, being recognized as one of the significant engineering accomplishments, work exceptionally well for the purposes they have been designed to achieve. Enabled by the advances in sensing, communication, computation, and actuation, smart power are rapidly growing in scale, inter-connectivity, and complexity. Major paradigm shifts in power grids include departing producer-controlled structures and transforming to more decentralized and consumer-interactive ones, being more distributed in electricity generation, enhancing the coupling between the physical and cyber layers, and operating in more variable and stochastic conditions. Driven by these emerging needs, power grids are anticipated to be complex and smart networked platforms in which large volume of high-dimensional and complex data is routinely generated, exchanged, and processed for various monitoring, control, and scheduling purposes. The papers in this section cover some of the recent research in the theory of complex systems with applications to power grid operations, which present novel research contributions in all aspects of complex and large-scale systems of relevance and significance in power grids.","Title: Theoretical guarantees for the design of near globally optimal static distributed controllers.\nYear: 2016\n\nAbstract: This paper is concerned with the optimal distributed control problem for linear discrete-time deterministic and stochastic systems. The objective is to design a stabilizing static distributed controller whose performance is close to that of the optimal centralized controller (if such controller exists). In our previous work, we have developed a computational framework to transform centralized controllers into distributed ones for deterministic systems. By building on this result, we derive strong theoretical lower bounds on the optimality guarantee of the designed distributed controllers and show that the proposed mathematical framework indirectly maximizes the derived lower bound while striving to achieve a closed-loop stability. Furthermore, we extend the proposed design method to stochastic systems that are subject to input disturbance and measurement noise. The developed optimization problem has a closed-form solution (explicit formula) and can be easily deployed for large-scale systems that require low computational efforts. The proposed approach is tested on a power network and random systems to demonstrate its efficacy.","Title: Characterization Of Rank-Constrained Feasibility Problems Via A Finite Number Of Convex Programs\nYear: 2016\n\nAbstract: In this paper, the rank-constrained matrix feasibility problem is considered, where an unknown positive semidefinite (PSD) matrix is to be found based on a set of linear specifications. First, we consider a scenario for which the number of given linear specifications is at least equal to the dimension of the corresponding space of rank-constrained matrices. Given a nominal symmetric and PSD matrix, we design a convex program with the property that every arbitrary matrix could be recovered by this convex program based on its specifications if: i) the unknown matrix has the same size and rank as the nominal matrix, and ii) the distance between the nominal and unknown matrices is less than a positive constant number. It is also shown that if the number of specifications is nearly doubled, then it is possible to recover all rank constrained PSD matrices through a finite number of convex programs. The results of this paper are demonstrated on many randomly generated matrices.","Title: Power System State Estimation With A Limited Number Of Measurements\nYear: 2016\n\nAbstract: This paper is concerned with the power system state estimation (PSSE) problem, which aims to find the unknown operating point of a power network based on a given set of measurements. The measurements of the PSSE problem are allowed to take any arbitrary combination of nodal active powers, nodal reactive powers, nodal voltage magnitudes and line flows. This problem is non-convex and NP-hard in the worst case. We develop a set of convex programs with the property that they all solve the non-convex PSSE problem in the case of noiseless measurements as long as the voltage angles are relatively small. This result is then extended to a general PSSE problem with noisy measurements, and an upper bound on the estimation error is derived. The objective function of each convex program developed in this paper has two terms: one accounting for the non-convexity of the power flow equations and another one for estimating the noise levels. The proposed technique is demonstrated on the 1354-bus European network.","Title: Power System State Estimation With Line Measurements\nYear: 2016\n\nAbstract: This paper deals with the power flow (PF) and power system state estimation (PSSE) problems, which play a central role in the analysis and operation of electric power networks. The objective is to find the complex voltage at each bus of a network based on a given set of noiseless or noisy measurements. In this paper, it is assumed that at least two groups of measurements are available: (i) nodal voltage magnitudes, and (ii) one active flow per line for a subset of lines covering a spanning tree of the network. The PF feasibility problem is first cast as an optimization problem by adding a suitable quadratic objective function. Then, the semidefinite programming (SDP) relaxation technique is used to handle the inherent non-convexity of the PF problem. It is shown that as long as voltage angle differences across the lines of the network are not too large (e.g., less than 90 degrees for lossless networks), the SDP problem finds the correct PF solution. By capitalizing on this result, a penalized convex problem is designed to solve the PSSE problem. In addition to a linear term inherited from the SDP relaxation of the PF problem, a cost based on the weighted least absolute value is incorporated in the objective for fitting noisy measurements. The optimal solution of the penalized convex problem is shown to feature a dominant rank-one component formed by lifting the true state of the system. An upper bound on the estimation error is also derived, which depends on the noise power. It is shown that the estimation error reduces as the number of measurements increases. Numerical results for the 1354-bus European system are reported to corroborate the merits of the proposed convexification framework. The mathematical framework developed in this work can be used to study the PSSE problem with other types of measurements.","Title: A Strong Semidefinite Programming Relaxation Of The Unit Commitment Problem\nYear: 2016\n\nAbstract: The unit commitment (UC) problem aims to find an optimal schedule of generating units subject to the demand and operating constraints for an electricity grid. The majority of existing algorithms for the UC problem rely on solving a series of convex relaxations by means of branch-and-bound or cutting-planning methods. In this paper, we develop a strengthened semidefinite program (SDP) for the UC problem by first deriving certain valid quadratic constraints and then relaxing them to linear matrix inequalities. These valid inequalities are obtained by the multiplication of the linear constraints of the UC problem such as the flow constraints of two different lines. The performance of the proposed convex relaxation is evaluated on several instances of the UC problem. For most of the instances, globally optimal integer solutions are obtained by solving a single convex problem. Since the proposed technique leads to a large number of valid quadratic inequalities, an iterative procedure is devised to impose a small number of such valid inequalities. For the cases where the strengthened SDP does give a global integer solution, we incorporate other valid inequalities, including a set of Boolean quadric polytope constraints. The proposed relaxations are extensively tested on various IEEE power systems in simulations.","Title: Finding Low-rank Solutions of Sparse Linear Matrix Inequalities using Convex Optimization.\nYear: 2017\n\nAbstract: This paper is concerned with the problem of finding a low-rank solution of an arbitrary sparse linear matrix inequality (LMI). To this end, we map the sparsity of the LMI problem into a graph. We develop a mathematical framework to relate the rank of the minimum-rank solution of the LMI problem to the sparsity of its underlying graph. Furthermore, we propose three graph theoretic convex programs to obtain a low-rank solution. Two of these convex optimization problems are based on a tree decomposition of the sparsity graph. The third one does not rely on any computationally expensive graph analysis and is always polynomial-time solvable, at the cost of offering a milder theoretical guarantee on the rank of the obtained solution compared to the other two methods. The results of this work can be readily applied to three separate problems of minimum rank matrix completion, conic relaxation for polynomial optimization, and affine rank minimization. The results are finally illustrated on two applications of optimal distributed control and nonlinear optimization for electrical networks.","Title: On The Convexity Of Optimal Decentralized Control Problem And Sparsity Path\nYear: 2017\n\nAbstract: This paper is concerned with an important special case of the stochastic optimal decentralized control (SODC) problem, where the objective is to design a static structurally constrained controller for a stable stochastic system. This problem is non-convex and hard to solve in general. We show that if either the measurement noise covariance or the input weighting matrix is not too small, the problem is locally convex. Under such circumstances, the design of a decentralized controller with a bounded norm subject to an arbitrary sparsity pattern is naturally a convex problem. We also study the problem of designing a sparse controller using a regularization technique, where the control structure is not pre-specified but penalized in the objective function. Under some genericity assumptions, we prove that this method is able to design a decentralized controller with any arbitrary sparsity level. Although this paper is focused on stable systems, the results can be generalized to unstable systems as long as an initial stabilizing controller with a desirable structure is known a priori.","Title: Guest Editorial Distributed Control and Efficient Optimization Methods for Smart Grid.\nYear: 2017\n\nAbstract: Smart grid proactively uses the state-of-the-art technologies in communications, computing, and control to improve efficiency, reliability, sustainability, and stability of the electrical grid. In particular, distribution networks are expected to undergo dramatic changes by incorporating a large number of sensors and thousands of controllable devices such as distributed generators, batteries and f...","Title: A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems.\nYear: 2017\n\nAbstract: Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. This paper surveys the literature of distributed algorithms wi...","Title: A semidefinite programming relaxation under false data injection attacks against power grid AC state estimation.\nYear: 2017\n\nAbstract: The integration of sensing and information technology renders the power grid susceptible to cyber-attacks. To understand how vulnerable the state estimator is, we study its behavior under the worst attacks possible. A general false data injection attack (FDIA) based on the AC model is formulated, where the attacker manipulates sensor measurements to mislead the system operator to make decisions based on a falsified state. To stage such an attack, the optimization problem incorporates constraints of limited resources (allowing only a limited number of measurements to be altered), and stealth operation (ensuring the cyber hack cannot be identified by the bad data detection algorithm). Due to the nonlinear AC power flow model and combinatorial selection of compromised sensors, the problem is nonconvex and cannot be solved in polynomial time; however, it is shown that convexification of the original problem based on a semidefinite programming (SDP) relaxation and a sparsity penalty is able to recover a near-optimal solution. This represents the first study to solve the AC-based FDIA. Simulations on a 30-bus system illustrate that the proposed attack requires only sparse sensor manipulation and remains stealthy from the residual-based bad data detection mechanism. In light of the analysis, this study raises new challenges on grid defense mechanism and attack detection strategy.","Title: A Scalable Method For Designing Distributed Controllers For Systems With Unknown Initial States\nYear: 2017\n\nAbstract: The optimal distributed control (ODC) problem for linear discrete-time systems is studied in this paper. The goal is to design a static stabilizing controller that offers some optimality guarantee for the closed-loop system and yet respects an imposed communication structure. Unlike the traditional centralized control problem, the ODC problem is hard to solve in general. Recently, we have introduced an efficient and scalable algorithm to design a distributed controller whose performance is close to that of a given centralized controller, provided that the initial state of the system is known. In this work, we generalize the proposed method to systems with uncertain initial states. The objective is to make the performance of the designed distributed controller be as closely as possible to that of the optimal centralized counterpart for every initial state in the uncertainty region. It is shown that the developed method requires solving a convex problem. Strong theoretical lower bounds are provided on the optimality guarantee of the synthesized distributed controller. To illustrate the effectiveness of the proposed method, case studies on aircraft formation and frequency control of power systems are offered.","Title: Modified Interior-Point Method For Large-And-Sparse Low-Rank Semidefinite Programs\nYear: 2017\n\nAbstract: Semidefinite programs (SDPs) are powerful theoretical tools that have been studied for over two decades, but their practical use remains limited due to computational difficulties in solving large-scale, realistic-sized problems. In this paper, we describe a modified interior-point method for the efficient solution of large-and-sparse low-rank SDPs, which finds applications in graph theory, approximation theory, control theory, sum-of-squares, etc. Given that the problem data is large-and-sparse, conjugate gradients (CG) can be used to avoid forming, storing, and factoring the large and fully-dense interior-point Hessian matrix, but the resulting convergence rate is usually slow due to ill-conditioning. Our central insight is that, for a rank-k, size-n SDP, the Hessian matrix is ill-conditioned only due to a rank-nk perturbation, which can be explicitly computed using a size-n eigendecomposition. We construct a preconditioner to \"correct\" the low-rank perturbation, thereby allowing preconditioned CG to solve the Hessian equation in a few tens of iterations. This modification is incorporated within SeDuMi, and used to reduce the solution time and memory requirements of large-scale matrix-completion problems by several orders of magnitude.","Title: Promises Of Conic Relaxations In Optimal Transmission Switching Of Power Systems\nYear: 2017\n\nAbstract: This paper studies the problem of optimal transmission switching (OTS) for power systems. The goal is to identify a topology of the power grid that minimizes the cost of the system operation while satisfying the physical and operational constraints. Most of the existing methods are based on converting the OTS problem into a mixed-integer linear program (MILP), and then iteratively solving a series of convex problems. The performance of these methods depends heavily on the strength of the MILP formulation. In this paper, we first show that finding the strongest variable upper bounds to be used in the MILP formulation of the OTS problem based on the big-M method is NP-hard. Then, we propose a convex conic relaxation of the big-M MILP formulation based on a semidefinite program (SDP). Strong valid inequalities using the reformulation-linearization technique (RLT) are proposed to strengthen the SDP relaxation by multiplying different linear constraints and then convexifying them in a lifted space. We extensively evaluate the performance of the proposed method on IEEE benchmarks systems.","Title: Spurious Critical Points In Power System State Estimation\nYear: 2018\n\nAbstract: The power systems state estimation problem computes the set of complex voltage phasors given quadratic measurements using nonlinear least squares (NLS). This is a nonconvex optimization problem, so even in the absence of measurement errors, local search algorithms like Newton / Gauss-Newton can become \"stuck\" at local minima, which correspond to nonsensical estimations. In this paper, we observe that local minima cease to be an issue as redundant measurements are added. Posing state estimation as an instance of the quadratic recovery problem, we derive a bound for the distance between the true solution and the nearest spurious local minimum. We use the bound to show that critical points of the nonconvex least squares objective become increasing rare and far-away from the true solution with the addition of redundant information.","Title: High-Performance Cooperative Distributed Model Predictive Control For Linear Systems\nYear: 2018\n\nAbstract: Distributed model predictive control (DMPC) has been proven a successful method in regulating the operation of large-scale networks of constrained dynamical systems. This paper is concerned with cooperative DMPC in which the control actions of the systems are derived by the solution of a system-wide optimization problem. To exploit the merits of distributed computation algorithms, we investigate how to approximate this system-wide optimization problem by a number of loosely coupled subproblems. In this context, the main challenge is to design appropriate terminal cost-to-go functions and invariant sets that comply with the coupling pattern of the network. The goal of this paper is to present a unified framework for the synthesis of a terminal distributed controller, cost-to-go function and invariant set based on an existing optimal centralized terminal controller. We construct an objective function for the synthesis problem, which mathematically quantifies the closeness of the given centralized and distributed control systems. This objective function is formulated using the optimizer of a robust optimization problem. Conditions for global Lyapunov stability are imposed in the synthesis problem in a way that allows the terminal cost-to-go function and invariant set to admit the desired distributed structure. We illustrate the effectiveness of the proposed method on a benchmark spring-mass-damper problem.","Title: Conic Relaxations for Power System State Estimation With Line Measurements.\nYear: 2018\n\nAbstract: This paper deals with the nonconvex power system state estimation (PSSE) problem, which plays a central role in the monitoring and operation of electric power networks. Given a set of noisy measurements, PSSE aims at estimating the vector of complex voltages at all buses of the network. This is a challenging task due to the inherent nonlinearity of power flows (PFs), for which the existing methods...","Title: Stability-Certified Reinforcement Learning: A Control-Theoretic Perspective\nYear: 2018\n\nAbstract: We investigate the important problem of certifying stability of reinforcement learning policies when interconnected with nonlinear dynamical systems. We show that by regulating the partial gradients of policies, strong guarantees of robust stability can be obtained based on a proposed semidefinite programming feasibility problem. The method is able to certify a large set of stabilizing controllers by exploiting problem-specific structures; furthermore, we analyze and establish its (non)conservatism. Empirical evaluations on two decentralized control tasks, namely multi-flight formation and power system frequency regulation, demonstrate that the reinforcement learning agents can have high performance within the stability-certified parameter space and also exhibit stable learning behaviors in the long run.","Title: A Low-Complexity Parallelizable Numerical Algorithm for Sparse Semidefinite Programming.\nYear: 2018\n\nAbstract: In the past two decades, the semidefinite programming (SDP) technique has been proven to be extremely successful in the convexification of hard optimization problems appearing in graph theory, control theory, polynomial optimization theory, and many areas in engineering. In particular, major power optimization problems, such as optimal power flow, state estimation, and unit commitment, can be form...","Title: Transformation of Optimal Centralized Controllers Into Near-Globally Optimal Static Distributed Controllers.\nYear: 2019\n\nAbstract: This paper is concerned with the optimal static distributed control problem for linear discrete-time deterministic and stochastic systems. The objective is to design a stabilizing static distributed controller whose performance is close to that of the optimal centralized controller. To this end, we first consider deterministic systems, where the initial state is either given or belongs to a known ...","Title: Convexification of generalized network flow problem\nYear: 2019\n\nAbstract: This paper is concerned with the minimum-cost flow problem over an arbitrary flow network. In this problem, each node is associated with some possibly unknown injection and each line has two unknown flows at its ends that are related to each other via a nonlinear function. Moreover, all injections and flows must satisfy certain box constraints. This problem, named generalized network flow (GNF), is highly non-convex due to its nonlinear equality constraints. Under the assumption of monotonicity and convexity of the flow and cost functions, a convex relaxation is proposed, which is shown to always obtain globally optimal injections. This relaxation may fail to find optimal flows because the mapping from injections to flows is not unique in general. We show that the proposed relaxation, named convexified GNF (CGNF), obtains a globally optimal flow vector if the optimal injection vector is a Pareto point. More generally, the network can be decomposed into two subgraphs such that the lines between the subgraphs are congested at optimality and that CGNF finds correct optimal flows over all lines of one of these subgraphs. We also fully characterize the set of all globally optimal flow vectors, based on the optimal injection vector found via CGNF. In particular, we show that this solution set is a subset of the boundary of a convex set, and may include an exponential number of disconnected components. A primary application of this work is in optimization over electrical power networks.","Title: A Convex Approximation Of Optimal Distributed Controller In Frequency Domain\nYear: 2018\n\nAbstract: We study the optimal distributed control (ODC) problem and propose a design method based on the approximation of the H-2 performance using the optimal centralized controller. The designed distributed controller obeys a prescribed sparsity pattern in the frequency domain. The proposed method enables a convex approximation of the distributed controller problem, which has a closed-form solution with sub-optimality guarantees. After introducing the notion of rank-preserving weights, we give sufficient conditions for the controller to be proper, and furthermore characterize the set of controllers that can be obtained by the proposed technique via fine-tuning the algorithm parameters. The results are applied to the linear-quadratic regulator problem and to the purely decentralized case with a diagonal sparsity pattern, where certain connections to the simple methods of thresholding and averaging are discovered. Numerical examples are provided to demonstrate the effectiveness of the developed method.","Title: Analysis Of Semidefinite Programming Relaxation Of Optimal Power Flow For Cyclic Networks\nYear: 2018\n\nAbstract: The optimal power flow (OPF) problem determines an optimal operating point of the power network that minimizes a certain objective function subject to physical and network constraints. There has been a great deal of attention in convex relaxation of the OPF problem in recent years, and it has been shown that a semidefinite programming (SDP) relaxation can solve different classes of the nonconvex OPF problem to global or near-global optimality. Although it is known that the SDP relaxation is exact for radial networks under various conditions, solving the OPF problem for cyclic networks needs further research. In this paper, we propose sufficient conditions under which the SDP relaxation is exact for special but important cyclic networks. More precisely, when the objective function is a linear function of active powers, we show that the SDP relaxation is exact for odd cycles under certain conditions. Also, the exactness of the SDP relaxation for simple cycles of size 3 and 4 is proved under different technical conditions. The existence of rank-1 or -2 SDP solutions for weakly-cyclic networks is also proved in both lossy and lossless cases. In addition, when the objective function is an increasing function of reactive powers, we prove that the SDP relaxation is exact under certain conditions. This result justifies why the sum of reactive powers acts as a low-rank-promoting term for OPF. The findings of this paper provide intuition into the behavior of SDPs for different building blocks of cyclic networks.","Title: Conic Approximation with Provable Guarantee for Traffic Signal Offset Optimization\nYear: 2018\n\nAbstract: We consider the offset optimization problem that coordinates the offsets of signalized intersections to reduce vehicle queues in large-scale signalized traffic networks. We adopt a recent approach that transforms the offset optimization problem into a complex-valued quadratically-constrained quadratic program (QCQP). Using the special structure of the QCQP, we provide a π /4-approximation algorithm to find a near-global solution based on the optimal solution of a semidefinite program (SDP) relaxation. Although large-scale SDPs are generally hard to solve, we exploit sparsity structures of traffic networks to propose a numerical algorithm that is able to efficiently solve the SDP relaxation of the offset optimization problem. The developed algorithm relies on a tree decomposition to reformulate the large-scale problem into a reduced-complexity SDP. Under the practical assumption that a real-world traffic network has a bounded treewidth, we show that the complexity of the overall algorithm scales near-linearly with the number of intersections. The results of this work, including the bounded treewidth property, are demonstrated on the Berkeley, Manhattan, and Los Angeles networks. From numerical experiments it is observed that the algorithm has a linear empirical time complexity, and the solutions of all cases achieve a near-globally optimal guarantee of more than 0.99.","Title: Conic Optimization For Robust Quadratic Regression: Deterministic Bounds And Statistical Analysis\nYear: 2018\n\nAbstract: This paper is concerned with the robust quadratic regression problem, where the goal is to find the unknown parameters (state) of a system modeled by nonconvex quadratic equations based on observational data. In this problem, a sparse subset of equations are subject to errors (noise values) of arbitrary magnitudes. We propose two techniques based on conic optimization to address this problem. The first one is a penalized conic relaxation, whereas the second one is a more complex iterative conic optimization equipped with a hard thresholding operator. We derive a deterministic bound for the penalized conic relaxation to quantify how many bad measurements the algorithm can tolerate without producing a nonzero estimation error. This bound is then analyzed for Gaussian systems, and it is proved that the proposed method allows up to a square root of the total number of measurements to be grossly erroneous. If the number of measurements is sufficiently large, we show that the iterative conic optimization method recovers the unknown state precisely even when up to a constant fraction of equations are arbitrarily wrong in the Gaussian case. The efficacy of the developed methods is demonstrated on synthetic data and a European power grid.","Title: Control-Theoretic Analysis of Smoothness for Stability-Certified Reinforcement Learning\nYear: 2019\n\nAbstract: It is critical to obtain stability certificate before deploying reinforcement learning in real-world mission-critical systems. This study justifies the intuition that smoothness (i.e., small changes in inputs lead to small changes in outputs) is an important property for stability-certified reinforcement learning from a control-theoretic perspective. The smoothness margin can be obtained by solving a feasibility problem based on semi-definite programming for both linear and nonlinear dynamical systems, and it does not need to access the exact parameters of the learned controllers. Numerical evaluation on nonlinear and decentralized frequency control for large-scale power grids demonstrates that the smoothness margin can certify stability during both exploration and deployment for (deep) neural-network policies, which substantially surpass nominal controllers in performance. The study opens up new opportunities for robust Lipschitz continuous policy learning. © 2018 IEEE.","Title: Sparse Semidefinite Programs With Near-Linear Time Complexity\nYear: 2018\n\nAbstract: Some of the strongest polynomial-time relaxations to NP-hard combinatorial optimization problems are semidefinite programs (SDPs), but their solution complexity of up to O(n (6.5) L) time and O(n(4)) memory for L accurate digits limits their use in all but the smallest problems. Given that combinatorial SDP relaxations are often sparse, a technique known as chordal conversion can sometimes reduce complexity substantially. In this paper, we describe a modification of chordal conversion that allows any general-purpose interiorpoint method to solve a certain class of sparse SDPs with a guaranteed complexity of O(n(1.5) L) time and O(n) memory. To illustrate the use of this technique, we solve the MAX k-CUT relaxation and the Lovasz Theta problem on power system models with up to n = 13659 nodes in 5 minutes, using SeDuMi v1.32 on a 1.7 GHz CPU with 16 GB of RAM. The empirical time complexity for attaining L decimal digits of accuracy is approximate to 0.001n (1.1) L seconds.","Title: Efficient Algorithm For Large-And-Sparse Lmi Feasibility Problems\nYear: 2018\n\nAbstract: Linear matrix inequalities (LMIs) play a fundamental role in robust and optimal control theory. However, their practical use remains limited, in part because their solution complexities of O(n(6.5)) time and O(n(4)) memory limit their applicability to systems containing no more than a few hundred state variables. This paper describes a Newton-PCG algorithm to efficiently solve large-and-sparse LMI feasibility problems, based on efficient log-det barriers for sparse matrices. Assuming that the data matrices share a sparsity pattern that admits a sparse Cholesky factorization, we prove that the algorithm converges in linear O(n) time and memory. The algorithm is highly efficient in practice: we solve LMI feasibility problems over power system models with as many as n = 5738 state variables in 2 minutes on a standard workstation running MATLAB.","Title: Sharp Restricted Isometry Bounds for the Inexistence of Spurious Local Minima in Nonconvex Matrix Recovery.\nYear: 2019\n\nAbstract: Nonconvex matrix recovery is known to contain no spurious local minima under a restricted isometry property (RIP) with a sufficiently small RIP constant delta. If delta is too large, however, then counterexamples containing spurious local minima are known to exist. In this paper, we introduce a proof technique that is capable of establishing sharp thresholds on delta to guarantee the inexistence of spurious local minima. Using the technique, we prove that in the case of a rank-1 ground truth, an RIP constant of delta < 1/2 is both necessary and sufficient for exact recovery from any arbitrary initial point (such as a random point). We also prove a local recovery result: given an initial point x(0) satisfying f(x(0)) <= (1 - delta)(2) f(0), any descent algorithm that converges to second-order optimality guarantees exact recovery. Keywords: matrix factorization, nonconvex optimization, Restricted Isometry Property, matrix sensing, spurious local minima","Title: Monotonicity Between Phase Angles And Power Flow And Its Implications For The Uniqueness Of Solutions\nYear: 2019\n\nAbstract: This paper establishes sufficient conditions for the uniqueness of power flow solutions in an AC power system via the monotonic relationship between real power flow and the phase angle difference. More specifically, we prove that strict monotonicity holds if the angle difference is bounded by the steady-state stability limit in a power system with a series-parallel topology, or if transmission losses are sufficiently low. In both cases, a vector of voltage phase angles can be uniquely determined (up to an absolute phase shift) given a vector of active power injections within the realizable range. The implication of this result for classical power flow analysis is that, under the conditions specified above, the problem has a unique physically realizable solution if the phasor voltage magnitudes are tightly controlled.","Title: Power Grid AC-based State Estimation: Vulnerability Analysis Against Cyber Attacks\nYear: 2019\n\nAbstract: To ensure grid efficiency and reliability, power system operators continuously monitor the operational characteristics of the grid through a critical process called state estimation (SE), which performs the task by filtering and fusing various measurements collected from grid sensors. This study analyzes the vulnerability of the key operation module, namely ac-based SE, against potential cyber attacks on data integrity, also known as false data injection attack (FDIA). A general form of FDIA can be formulated as an optimization problem, whose objective is to find a stealthy and sparse data injection vector on the sensor measurements with the aim of making the state estimate spurious and misleading. Due to the nonlinear ac measurement model and the cardinality constraint, the problem includes both continuous and discrete nonlinearities. To solve the FDIA problem efficiently, we propose a novel convexification framework based on semidefinite programming (SDP). By analyzing a globally optimal SDP solution, we delineate the “attackable region” for any given set of measurement types and grid topology, where the spurious state can be falsified by FDIA. Furthermore, we prove that the attack is stealthy and sparse, and derive performance bounds. Simulation results on various IEEE test cases indicate the efficacy of the proposed convexification approach. From the grid protection point of view, the results of this study can be used to design a security metric for the current practice against cyber attacks, redesign the bad data detection scheme, and inform proposals of grid hardening. From a theoretical point of view, the proposed framework can be used for other nonconvex problems in power systems and beyond.","Title: On Sampling Complexity of the Semidefinite Affine Rank Feasibility Problem\nYear: 2019\n\nAbstract: In this paper, we study the semidefinite affine rank feasibility problem, which consists in finding a positive semidefinite matrix of a given rank from its linear measurements. We consider the semidefinite programming relaxations of the problem with different objective functions and study their properties. In particular, we propose an analytical bound on the number of relaxations that are sufficient to solve in order to obtain a solution of a generic instance of the semidefinite affine rank feasibility problem or prove that there is no solution. This is followed by a heuristic algorithm based on semidefinite relaxation and an experimental proof of its performance on a large sample of synthetic data.","Title: Convexification of Power Flow Equations in the Presence of Noisy Measurements\nYear: 2019\n\nAbstract: This paper is concerned with the power system state estimation (PSSE) problem that aims to find the unknown operating point of a power network based on a given set of measurements. We first study the power flow (PF) problem as an important special case of PSSE, which is known to be non-convex and NP-hard in the worst case. To this end, we propose a set of semidefinite programs (SDPs) with the property that they all solve the PF problem as long as the voltage angles are relatively small. Associated with each SDP, we explicitly characterize the set of all complex voltages that can be recovered via that convex problem. As a generalization, the design of an SDP problem that recovers multiple nominal points and a neighborhood around each point is also cast as a convex program. The results are then extended to the PSSE problem, where the measurements used in the PF problem are subject to noise. A two-term objective function is employed for each convex program developed for the PSSE problem: (i) one term accounting for the non-convexity of the power flow equations, (ii) another one for estimating the noise levels. An upper bound on the estimation error is derived with respect to the noise level and the proposed techniques are demonstrated on multiple test systems, including a 9241-bus European network. Although the focus of the paper is on power networks, the developed results apply to every arbitrary state estimation problem with quadratic measurement equations.","Title: Escaping Locally Optimal Decentralized Control Polices via Damping.\nYear: 2020\n\nAbstract: We study the design of an optimal static decentralized controller with a quadratic cost and propose a variant of the homotopy continuation method using a damping technique. This method generates a series of optimal distributed control (ODC) problems via a continuous variation of the system parameters. Diverging from the classical theme of tracking a specific trajectory of locally optimal controllers for these ODC problems, we focus on the possibility of leveraging local-search algorithms to locate the globally optimal trajectory among several locally optimal controller trajectories. We analyze the continuity and asymptotic properties of the locally and globally optimal controller trajectories as the damping parameter varies. In particular, we prove that under certain conditions, there is no spurious locally optimal controller for an ODC problem with favorable control structure and a large damping parameter. As a result, the proposed method is able to locate the globally optimal trajectory with a suitable discretization in the space of the damping parameter. To demonstrate the effectiveness of this technique, it is shown that even for instances with an exponential number of connected components, damping could merge the trajectories of all local solutions to the trajectory of the global solutions. We further illustrate the convoluted behavior of the locally optimal trajectories with numerical examples on random systems.","Title: Uniqueness of Power Flow Solutions Using Monotonicity and Network Topology\nYear: 2021\n\nAbstract: This article establishes sufficient conditions for the uniqueness of AC power flow solutions via the monotonic relationship between real power flow and the phase angle difference. More specifically, we prove that the P-Θ power flow problem has at most one solution for any acyclic or GSP graph. In addition, for arbitrary cyclic power networks, we show that multiple distinct solutions cannot exist under the assumption that angle differences across the lines are bounded by some limit related to the maximal girth of the network. In these cases, a vector of voltage phase angles can be uniquely determined (up to an absolute phase shift) given a vector of real power injections within the realizable range. The implication of this result for the classical power flow analysis is that under the conditions specified above, the problem has a unique physically realizable solution if the phasor voltage magnitudes are fixed. We also introduce a series-parallel operator and show that this operator obtains a reduced and easier-to-analyze model for the power system without changing the uniqueness of power flow solutions.","Title: Analysis of Spurious Local Solutions of Optimal Control Problems: One-Shot Optimization Versus Dynamic Programming\nYear: 2021\n\nAbstract: Dynamic programming (DP) has a rich theoretical foundation and a broad range of applications, especially in the classic area of optimal control and the recent area of reinforcement learning (RL). Many optimal control problems can be solved as a single optimization problem, named one-shot optimization, or via a sequence of optimization problems using DP. However, the computation of their global optima often faces the NP-hardness issue due to the non-linearity of the dynamics and non-convexity of the cost, and thus only local optimal solutions may be obtained at best. Furthermore, in many cases arising in machine learning and model-free approaches, DP is the only viable choice, and therefore it is essential to understand when DP combined with a local search solver works. In this work, we introduce the notions of spurious local minimizers for the one-shot optimization and spurious local minimum policies for DP, and show that there is a deep connection between them. In particular, we prove that under mild conditions the DP method using local search can successfully solve the optimal control problem to global optimality if and only if the one-shot optimization is free of spurious solutions. This result paves the way to understand the performance of local search methods in optimal control and RL.","Title: No Spurious Solutions in Non-convex Matrix Sensing: Structure Compensates for Isometry\nYear: 2021\n\nAbstract: The paper is concerned with the theoretical explanation of the recent empirical success of solving the low-rank matrix sensing problem via nonconvex optimization. It is known that under an incoherence assumption (namely, RIP) on the sensing operator, the optimization problem has no spurious local minima. This assumption is too strong for real-world applications where the amount of data cannot be sufficiently high. We develop the notion of Kernel Structure Property (KSP), which can be used alone or combined with RIP in this context. KSP explains how the inherent structure of an operator contributes to the non-existence of spurious local minima. As a special case, we study sparse sensing operators that have a low-dimensional representation. Using KSP, we obtain novel necessary and sufficient conditions for no spurious solutions in matrix sensing and demonstrate their usefulness in analytical and numerical studies.","Title: Diminishing Regret for Online Nonconvex Optimization\nYear: 2021\n\nAbstract: A single nonconvex optimization is NP-hard in the worst case, and so is a sequence of nonconvex problems viewed separately. For online nonconvex optimization (ONO) problems, widely used local search algorithms are guaranteed to track a sequence of local optima, but offer no promises about global optimality. In this paper, we introduce the concept of nonconvexity regret to measure the performance of a local search method against a global optimization solver for ONO. We define the notion of depth of a global minimum, and show that memory and random explorations drive the nonconvexity regret to zero if the variability of the objective function is low compared to the depth of the global minima. We prove probabilistic guarantees on the regret bound that depend on the evolution of the landscapes of the time-varying objective functions. Then, based on the notions of missing mass and 1-occupancy set, we develop a practical algorithm that works even when there is no such information on the landscapes. The theoretical results imply that the existence of a low-complexity optimization at any arbitrary time instance of ONO can nullify the NP-hardness of the entire ONO problem. The results are verified through numerical simulations.","Title: Smoothing Property of Load Variation Promotes Finding Global Solutions of Time-Varying Optimal Power Flow\nYear: 2021\n\nAbstract: This article analyzes solution trajectories for optimal power flow (OPF) with time-varying load. Despite its nonlinearity, time-varying OPF is commonly solved every 5–15 min using local-search algorithms. Failing to obtain the globally optimal solution of power optimization problems jeopardizes the grid's reliability and causes financial and environmental issues. The objective of this article is t...","Title: A Dual Approach to Constrained Markov Decision Processes with Entropy Regularization\nYear: 2022\n\nAbstract: We study entropy-regularized constrained Markov decision processes (CMDPs) under the soft-max parameterization, in which an agent aims to maximize the entropy-regularized value function while satisfying constraints on the expected total utility. By leveraging the entropy regularization, our theoretical analysis shows that its Lagrangian dual function is smooth and the Lagrangian duality gap can be decomposed into the primal optimality gap and the constraint violation. Furthermore, we propose an accelerated dual-descent method for entropy-regularized CMDPs. We prove that our method achieves the global convergence rate (O) over tilde (1/T) for both the optimality gap and the constraint violation for entropy-regularized CMDPs. A discussion about a linear convergence rate for CMDPs with a single constraint is also provided.","Title: Factorization Approach for Low-complexity Matrix Completion Problems: Exponential Number of Spurious Solutions and Failure of Gradient Methods\nYear: 2022\n\nAbstract: Burer-Monteiro (B-M) factorization approach can efficiently solve low-rank matrix optimization problems under the Restricted Isometry Property (RIP) condition. It is natural to ask whether BM factorization-based methods can succeed on any low-rank matrix optimization problems with a low information-theoretic complexity, i.e., polynomial-time solvable problems that have a unique solution. We provide negative answer to this question. We investigate the landscape of B-M factorized polynomial-time solvable matrix completion (MC) problems, which are the most popular subclass of low-rank matrix optimization problems without the RIP condition. We construct an instance of polynomial-time solvable MC problems with exponentially many spurious local minima, which leads to the failure of most gradient-based methods. We define a new complexity metric that measures the solvability of low-rank matrix optimization problems based on B-M factorization approach. In addition, we show that more measurements can deteriorate the landscape, which further reveals the unfavorable behavior of B-M factorization.","Title: When Does MAML Objective Have Benign Landscape?\nYear: 2021\n\nAbstract: The paper studies the landscape of the optimization problem behind the Model-Agnostic Meta-Learning (MAML) algorithm. The goal of the study is to determine the global convergence of MAML on sequential decision-making tasks possessing a common structure. We investigate in what scenarios the benign optimization landscape of the underlying tasks results in a benign landscape of the corresponding MAML...","Title: Adversarial Attacks on Computation of the Modified Policy Iteration Method\nYear: 2021\n\nAbstract: Adversarial attacks on Markov decision processes (MDPs) and reinforcement learning (RL) have been studied in the literature in the context of robust learning and adversarial game theory. In this paper, we introduce a new notion of adversarial attacks on MDP and RL computation that is motivated by the emergence of edge computing. The large-scale computation of MDP and RL models in the form of value/policy iteration and Q-learning is being offloaded from agents to distributed servers, giving rise to edge reinforcement learning. By the inherently distributed nature of edge RL, the MDP/RL computation can be prone to adversarial attacks in different forms. We analyze a probabilistic model of adversarial attacks on the computation of the modified policy iteration method in which the principal contraction property of the Bellman operator is undermined with a certain probability in iterations of the policy evaluation step of the aforementioned method. This can result in luring the agent to search among suboptimal policies without improving the true values of policies. We prove that under certain conditions, the attacked modified policy iteration method can still converge to the vicinity of the optimal policy with high probability if the number of policy evaluation iterations is larger than a threshold that is logarithmic in the inverse of a desired precision. We also provide an upper bound on the number of iterations needed for the attacked modified policy iteration method to terminate, which holds with an associated confidence level.","Title: Damping With Varying Regularization in Optimal Decentralized Control\nYear: 2022\n\nAbstract: We study a homotopy continuation method for the design of an optimal static or dynamic decentralized controller to minimize a quadratic cost functional. The proposed method involves a combination of the classical local search technique in the space of control policies, a gradual damping of the system dynamics, and a gradual variation of a parameterized cost functional. A series of optimal decentralized control (ODC) problems is generated via a continuous variation of parameters. Unlike the classical homotopy literature, which focuses on tracking a specific trajectory, we study the ensemble of critical controller trajectories and show how the properties of the ensemble can be leveraged to find a globally optimal solution of the ODC problem. After guaranteeing the continuity and asymptotic properties of the proposed method, we prove that with enough damping, there is no spurious locally optimal controller for a block-diagonal control structure. This leads to a sufficient condition under which an iterative algorithm can find a global solution to a class of optimal decentralized control problems. The “damping property” introduced in this analysis is shown to be unique for general system matrices. Empirical observations are presented for instances with an exponential number of locally optimal decentralized controllers, where the developed method could find the global solution even when initialized at a poor local solution.","Title: Uniqueness of Power Flow Solutions Using Graph-Theoretic Notions\nYear: 2022\n\nAbstract: This article extends the uniqueness theory in (Park \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">et al.</i>\n, 2021) and establishes general necessary and sufficient conditions for the uniqueness of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$P$</tex-math></inline-formula>\n–\n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$\\Theta$</tex-math></inline-formula>\n power flow solutions in an AC power system using some properties of the monotone regime and the power network topology. We show that the necessary and sufficient conditions can lead to tighter sufficient conditions for the uniqueness in several special cases. Our results are based on the existing notion of maximal girth and our new notion of maximal eye. Moreover, we develop a series–parallel reduction method and search-based algorithms for computing the maximal eye and the maximal girth, which are necessary for the uniqueness analysis. Reduction to a single line using the proposed reduction method is guaranteed for 2-vertex-connected series–parallel graphs. The relations between the parameters of the network before and after reduction are obtained. It is verified on real-world networks that the computation of the maximal eye can be reduced to the analysis of a much smaller power network, while the maximal girth is computed during the reduction process.","Title: Role of sparsity and structure in the optimization landscape of non-convex matrix sensing\nYear: 2022\n\nAbstract: In this work, we study the optimization landscape of the non-convex matrix sensing problem that is known to have many local minima in the worst case. Since the existing results are related to the notion of restricted isometry property (RIP) that cannot directly capture the underlying structure of a given problem, they can hardly be applied to real-world problems where the amount of data is not exorbitantly high. To address this issue, we develop the notion of kernel structure property to obtain necessary and sufficient conditions for the inexistence of spurious local solutions for any class of matrix sensing problems over a given search space. This notion precisely captures the underlying sparsity and structure of the problem, based on tools in conic optimization. We simplify the conditions for a certain class of problems to show their satisfaction and apply them to data analytics for power systems.","Title: On the Connectivity Properties of Feasible Regions of Optimal Decentralized Control Problems\nYear: 2022\n\nAbstract: The optimal decentralized control (ODC) is an NP-hard problem with many applications in real-world systems. There is a recent trend of using local search algorithms for solving optimal control problems. However, the effectiveness of these methods depends on the connectivity property of the feasible region of the underlying optimization problem. In this article, for ODC problems with static controllers, we develop a novel criterion for certifying the connectivity of the feasible region in the case where the input and output matrices of the system dynamics are identity matrices. This criterion can be checked via an efficient algorithm, and it is used to prove that the number of communication networks leading to connected feasible regions is greater than a square root of the exponential number of possible communication networks (named patterns). For ODC problems with dynamic controllers, we prove that under certain mild conditions, the closure of the feasible region is always connected after some parameterization, for general communication networks and system dynamics.","Title: On the Global Optimum Convergence of Momentum-based Policy Gradient\nYear: 2022\n\nAbstract: Policy gradient (PG) methods are popular and efficient for large-scale reinforcement learning due to their relative stability and incremental nature. In recent years, the empirical success of PG methods has led to the development of a theoretical foundation for these methods. In this work, we generalize this line of research by establishing the first set of global convergence results of stochastic PG methods with momentum terms, which have been demonstrated to be efficient recipes for improving PG methods. We study both the soft-max and the Fishernon-degenerate policy parametrizations, and show that adding a momentum term improves the global optimality sample complexities of vanilla PG methods by (O) over tilde(epsilon(-1.5)) and (O) over tilde(epsilon(-1)), respectively, where epsilon > 0 is the target tolerance. Our results for the generic Fishernon-degenerate policy parametrizations also provide the first single-loop and finite-batch PG algorithm achieving an (O) over tilde (epsilon(-3)) global optimality sample complexity. Finally, as a byproduct, our analyses provide general tools for deriving the global convergence rates of stochastic PG methods, which can be readily applied and extended to other PG estimators under the two parametrizations."],"string":"[\n \"Title: Relationship between power loss and network topology in power systems\\nYear: 2010\\n\\nAbstract: This paper is concerned with studying how the minimum power loss in a power system is related to its network topology. The existing algorithms in the literature all exploit nonlinear, heuristic, or local search algorithms to find the minimum power loss, which make them blind to the network topology. Given certain constraints on power level, bus voltages, etc., a linear-matrix-inequality (LMI) optimization problem is derived, which provides a lower bound on the minimum active loss in the network. The proposed LMI problem has the property that its objective function depends on the loads and its matrix inequality constraint is related to the topology of the power system. This property makes it possible to address many important power problems, such as the optimal network reconfiguration and the optimal placement/sizing of distributed generation units in power systems. Moreover, a condition is provided under which the solution of the given LMI problem is guaranteed to be exactly equal to the minimum power loss. As justified mathematically and verified on IEEE test systems, this condition is expected to hold widely in practice, implying that a practical power loss minimization problem is likely to be solvable using a convex algorithm.\",\n \"Title: Controllability and observability of uncertain systems: A robust measure\\nYear: 2009\\n\\nAbstract: This paper deals with the class of polynomially uncertain continuous-time linear time-invariant (LTI) systems whose uncertainties belong to a semi-algebraic set. The objective is to determine the minimum of the smallest singular value of the controllability or observability Gramian over the uncertainty region. This provides a quantitative measure for the robust controllability or observability degree of the system. To this end, it is shown that the problem can be recast as a sum-of-squares (SOS) problem. In the special case when the uncertainty region is polytopic, the corresponding SOS formulation can be simplified significantly. One can apply the proposed method to any large-scale interconnected system to identify those inputs and outputs that are more effective in controlling the system. This enables the designer to simplify the control structure by ignoring those inputs and outputs whose contribution to the overall control operation is relatively weak. A numerical example is presented to demonstrate the efficacy of the results.\",\n \"Title: Solving large-scale linear circuit problems via convex optimization\\nYear: 2009\\n\\nAbstract: A broad class of problems in circuits, electromag- netics, and optics can be expressed as finding some parameters of a linear system with a specific type. This paper is concerned with studying this type of circuit using the available control techniques. It is shown that the underlying problem can be recast as a rank minimization problem that is NP-hard in general. In order to circumvent this difficulty, the circuit problem is slightly modified so that the resulting optimization becomes convex. This interesting result is achieved at the cost of complicating the structure of the circuit, which introduces a trade-off between the design simplicity and the implementation complexity. When it is strictly required to solve the original circuit problem, the elegant structure of the proposed rank minimization problem allows to employ a celebrated heuristic method to solve it efficiently. I. INTRODUCTION\",\n \"Title: Quantized Consensus by Means of Gossip Algorithm.\\nYear: 2012\\n\\nAbstract: This paper deals with the distributed averaging problem over a connected network of agents, subject to a quantization constraint. It is assumed that at each time update, only a pair of agents can update their own states in terms of the quantized data being exchanged. The agents are also required to communicate with one another in a stochastic fashion. It is shown that a quantized consensus is reached for an arbitrary quantizer by means of the stochastic gossip algorithm proposed in a recent paper. The expected value of the time at which a quantized consensus is reached is lower and upper bounded in terms of the topology of the graph for a uniform quantizer. In particular, it is shown that these bounds are related to the principal submatrices of the weighted Laplacian matrix. A convex optimization is also proposed to determine a set of probabilities used to pick a pair of agents that leads to a fast convergence of the gossip algorithm.\",\n \"Title: Robust Stability of LTI Systems Over Semialgebraic Sets Using Sum-of-Squares Matrix Polynomials\\nYear: 2008\\n\\nAbstract: This paper deals with the robust stability of discrete-time linear time-invariant systems with parametric uncertainties belonging to a semialgebraic set. It is asserted that the robust stability of any system over any semialgebraic set (satisfying a mild condition) is equivalent to solvability of a semidefinite programming (SDP) problem, which can be handled using the available software tools. The particular case of a semialgebraic set associated with a polytope is then investigated, and a computationally appealing method is proposed to attain the SDP problem by means of a sampling technique, introduced recently in the literature. Furthermore, it is shown that the current result encompasses the ones presented in some of the recent works. The efficacy of the proposed method is demonstrated through some illustrative examples, and the results are compared to some of the existing methods.\",\n \"Title: Robust controllability and observability degrees of polynomially uncertain systems\\nYear: 2009\\n\\nAbstract: This paper deals with the class of polynomially uncertain continuous-time linear time-invariant (LTI) systems whose uncertainties belong to a semi-algebraic set. The objective is to determine the minimum of the smallest singular value of the controllability or observability Gramian over the uncertainty region. This provides a quantitative measure for the robust controllability or observability degree of the system. To this end, it is shown that the problem can be recast as a sum-of-squares (SOS) problem. In the special case when the uncertainty region is polytopic, the corresponding SOS formulation can be simplified significantly. One can apply the proposed method to any large-scale interconnected system in order to identify those inputs and outputs that are more effective in controlling the system, in a robust manner. This enables the designer to simplify the control structure by ignoring those inputs and outputs whose contribution to the overall control operation is relatively weak. A numerical example is presented to demonstrate the efficacy of the results.\",\n \"Title: Stabilization of decentralized control systems by means of periodic feedback\\nYear: 2008\\n\\nAbstract: This paper deals with structurally constrained periodic control design for interconnected systems. It is assumed that the system is linear time-invariant (LTI), observable and controllable, and that its modes are distinct and nonzero. It is shown that the notions of a quotient fixed mode (QFM) and a structured decentralized fixed mode (SDFM) are equivalent for this class of systems. Then, it is proved that if the system is decentrally stabilizable, then one candidate for the decentralized stabilizing controller is a time-varying one consisting of a decentralized LTI discrete-time compensator and a zero-order hold. More specifically, the non-quotient fixed modes of the system will be eliminated via sampling for almost all sampling periods, while any QFM will still remain a fixed mode. The results obtained are ultimately extended to the case when the system has some repeated modes, none of which is a DFM.\",\n \"Title: Convexification of optimal power flow problem by means of phase shifters\\nYear: 2013\\n\\nAbstract: This paper is concerned with the convexification of the optimal power flow (OPF) problem. We have previously shown that this highly nonconvex problem can be solved efficiently via a convex relaxation after two approximations: (i) adding a sufficient number of virtual phase shifters to the network topology, and (ii) relaxing the power balance equations to inequality constraints. The objective of the present paper is to first provide a better understanding of the implications of Approximation (i) and then remove Approximation (ii). To this end, we investigate the effect of virtual phase shifters on the feasible set of OPF by thoroughly examining a cyclic system. We then show that OPF can be convexified under only Approximation (i), provided some mild assumptions are satisfied. Although this paper mainly focuses on OPF, the results developed here can be applied to several OPF-based emerging optimization problems for future electrical grids.\",\n \"Title: A graph-theoretic method to find decentralized fixed modes of LTI systems\\nYear: 2007\\n\\nAbstract: This paper deals with the decentralized pole assignability of interconnected systems by means of linear time-invariant (LTI) controllers. A simple graph-theoretic approach is proposed to identify the distinct decentralized fixed modes (DFMs) of the system, i.e., the unrepeated modes which cannot be moved by means of a LTI decentralized controller. The state-space representation of the system is transformed to the decoupled form using a proper change of coordinates. For any unrepeated mode, a matrix is then computed which resembles the transfer function matrix of the system at some point in the complex plane. A bipartite graph is constructed accordingly in terms of the computed matrix. Now, the problem of verifying if this mode is a DFM of the system reduces to checking if the constructed graph has a complete bipartite subgraph with a certain property. The sole restriction of this work is that it is only capable of identifying the distinct DFMs of a system. However, it is axiomatic that most of the modes of the real-world systems are normally distinct. The primary advantage of the present paper is its simplicity, compared to the existing ones which often require evaluating the rank of several matrices.\",\n \"Title: Robust Stabilizability Verification of Polynomially Uncertain LTI Systems\\nYear: 2007\\n\\nAbstract: This paper investigates the stabilizability of uncertain linear time-invariant (LTI) systems via structurally constrained controllers. First, an LTI uncertain system is considered whose state-space matrices depend polynomially on the uncertainty vector, defined over some region. It is shown that if the system is stabilizable by a structurally constrained controller in one point belonging to the region, then it is stabilizable by a controller with the same structure in all points belonging to the region, except for those located on an algebraic variety. Thus, if a system is stabilizable via a constrained controller at the nominal point, then it is almost always stabilizable at any operating point around the nominal model. It is also shown how this algebraic variety (or the dominant subvariety of it) can be computed efficiently. The results obtained in this paper encompass a broad range of the existing results in the literature on robust stability of the LTI systems, in addition to new ones.\",\n \"Title: Simultaneous LQ control of a set of LTI systems using constrained generalized sampled-data hold functions\\nYear: 2007\\n\\nAbstract: In this paper, sampled-data control of a set of continuous-time LTI systems is considered. It is assumed that a predefined guaranteed continuous-time quadratic cost function, which is, in fact, the sum of the performance indices for all systems, is given. The main objective here is to design a decentralized periodic output feedback controller with a prespecified form, e.g., polynomial, piecewise constant, exponential, etc., which minimizes the above mentioned guaranteed cost function. This problem is first formulated as a set of matrix inequalities, and then by using a well-known technique, it is reformulated as a LMI problem. The set of linear matrix inequalities obtained provides necessary and sufficient conditions for the existence of a decentralized optimal simultaneous stabilizing controller with the prespecified form (rather than a general form). Moreover, an algorithm is presented to solve the resultant LMI problem. Finally, the efficiency of the proposed method is demonstrated in two numerical examples.\",\n \"Title: Optimal decentralized control problem as a rank-constrained optimization.\\nYear: 2013\\n\\nAbstract: This paper is concerned with the long-standing optimal decentralized control (ODC) problem. The objective is to design a fixed-order decentralized controller for a discretetime system to minimize a given finite-time cost function subject to norm constraints on the input and output of the system. We cast this NP-hard problem as a quadratically-constrained quadratic program, and then reformulate it as a rank-constrained optimization. The reformulated problem is a semidefinite program (SDP) after removing its rank-1 constraint. Whenever the SDP relaxation has a rank-1 solution, a globally optimal decentralized controller can be recovered from this solution. This paper studies the rank of the minimum-rank solution of the SDP relaxation since this number may provide rich information about the level of the approximation needed to make the ODC problem tractable. Using our recently developed notion of \\\"nonlinear optimization over graph\\\", we propose a methodology to compute the rank of the minimum-rank solution of the SDP relaxation. In particular, we show that in the case where the unknown decentralized controller being sought needs to be static with a diagonal matrix gain, this rank is upper bounded by 4. Since the upper bound is close to 1 and does not depend on the order of the system, the ODC problem may not be as hard as it is thought to be. This paper also proposes a penalized SDP relaxation to heuristically enforce the few unwanted nonzero eigenvalues of the solution to diminish.\",\n \"Title: Performance improvement of robust controllers for polynomially uncertain systems\\nYear: 2010\\n\\nAbstract: This paper is concerned with the high-performance robust control of discrete-time linear time-invariant (LTI) systems with semi-algebraic uncertainty regions. It is assumed that a robustly stabilizing static controller is given whose gain depends polynomially on the uncertain variables. The problem of tuning this parameter-dependent gain with respect to a prescribed quadratic cost function is formulated as a sum-of-squares (SOS) optimization. This method leads to a near-optimal controller whose performance is better than that of the initial controller. It is shown that the results derived in the present work encompass the ones obtained in a recent paper. The efficacy of the results is elucidated by an example.\",\n \"Title: A Model Predictive Decentralized Control Scheme With Reduced Communication Requirement for Spacecraft Formation\\nYear: 2008\\n\\nAbstract: This brief investigates the control problem for a number of cooperative spacecraft with communication constraints. It is assumed that a set of cooperative local controllers corresponding to the individual spacecraft is given which satisfies the desired objectives of the formation. It is to be noted that due to the information exchange between the local controllers, the overall control structure can be considered centralized in general. However, communication in flight formation is expensive. Thus, it is desired to have some form of decentralization in control structure, which has a lower communication requirement. This decentralized controller consists of local estimators inherently, so that each local controller estimates the state of the whole formation. Necessary and sufficient conditions for the stability of the formation under the proposed decentralized controller are obtained. It is shown that the decentralized control system, if stable, behaves almost the same as its centralized counterpart. Moreover, robustness of the decentralized controller is studied and compared to that of the corresponding centralized controller. It is finally shown that the proposed decentralized controller comprises most of the features of its centralized counterpart. The efficacy of the proposed method is demonstrated through simulations.\",\n \"Title: Overlapping control design for multi-channel systems\\nYear: 2009\\n\\nAbstract: This paper deals with the decentralized overlapping control of interconnected systems. The notion of a quotient overlapping fixed mode (QOFM) is first introduced and it is shown that a mode of an interconnected linear time-invariant system can be shifted by means of a general decentralized overlapping controller if and only if it is not a QOFM. It is then asserted that any interconnected system with no unstable QOFM can be stabilized by using an appropriate finite-dimensional linear time-varying controller. It is also shown how the existing results aiming at designing a decentralized controller of a certain type such as generalized sampled-data hold function, finite-dimensional linear time-varying, and sampled-data can be utilized to design a decentralized overlapping controller of a desired form, in order to achieve any design specification. The efficacy of the results is elucidated through two numerical examples.\",\n \"Title: Message Passing for Dynamic Network Energy Management\\nYear: 2012\\n\\nAbstract: We consider a network of devices, such as generators, fixed loads, deferrable loads, and storage devices, each with its own dynamic constraints and objective, connected by lossy capacitated lines. The problem is to minimize the total network objective subject to the device and line constraints, over a given time horizon. This is a large optimization problem, with variables for consumption or generation in each time period for each device. In this paper we develop a decentralized method for solving this problem. The method is iterative: At each step, each device exchanges simple messages with its neighbors in the network and then solves its own optimization problem, minimizing its own objective function, augmented by a term determined by the messages it has received. We show that this message passing method converges to a solution when the device objective and constraints are convex. The method is completely decentralized, and needs no global coordination other than synchronizing iterations; the problems to be solved by each device can typically be solved extremely efficiently and in parallel. The method is fast enough that even a serial implementation can solve substantial problems in reasonable time frames. We report results for several numerical experiments, demonstrating the method's speed and scaling, including the solution of a problem instance with over 30 million variables in 52 minutes for a serial implementation; with decentralized computing, the solve time would be less than one second.\",\n \"Title: Convexification of Generalized Network Flow problem with application to power systems\\nYear: 2013\\n\\nAbstract: This paper is concerned with the minimum-cost flow problem over an arbitrary flow network. In this problem, each node is associated with some possibly unknown injection, each line has two unknown flows at its ends related to each other via a nonlinear function, and all injections and flows need to satisfy certain box constraints. This problem, named generalized network flow (GNF), is highly non-convex due to its nonlinear equality constraints. Under the practical assumption of monotonicity and convexity of the flow and cost functions, a convex relaxation is proposed, which always finds the optimal injections. This relaxation may fail to find optimal flows because the mapping from injections to flows might lead to an exponential number of solutions. However, once optimal injections are found in polynomial time, other techniques can be used to find a feasible set of flows corresponding to the injections. A primary application of this work is in optimization over power networks. Recent work on the optimal power flow (OPF) problem has shown that this non-convex problem can be solved efficiently using semidefinite programming (SDP) after two approximations: relaxing angle constraints (by adding virtual phase shifters) and relaxing power balance equations to inequality constraints. The results of this work prove two facts for the OPF problem: (i) the second approximation (on balance equations) is not needed in practice under a very mild angle assumption, and (ii) if the SDP relaxation fails to find a rank-one solution, the optimal injections (and not flows) may still be recovered from an undesirable high-rank solution.\",\n \"Title: On quantized consensus by means of gossip algorithm: part ii: convergence time\\nYear: 2009\\n\\nAbstract: This paper deals with the distributed averaging problem over a connected network of agents, subject to a quantization constraint. It is assumed that at each time update, only a pair of agents can update their own numbers in terms of the quantized data being exchanged. The agents are also required to communicate with one another in a stochastic fashion. In the first part of the paper, it was shown that the quantized consensus is reached by means of a stochastic gossip algorithm proposed in a recent paper, for any arbitrary quantization. The current part of the paper considers the expected value of the time at which the quantized consensus is reached. This quantity (corresponding to the worst case) is lower and upper bounded in terms of the topology of the graph, for uniform quantization. In particular, it is shown that the upper bound is related to the principal minors of the weighted Laplacian matrix. A convex optimization is also proposed to determine the set of probabilities (used to pick a pair of agents) which leads to the fast convergence of the gossip algorithm.\",\n \"Title: Control of continuous-time LTI systems by means of structurally constrained controllers\\nYear: 2008\\n\\nAbstract: This paper deals with the characterization of the fixed modes of multi-channel systems with respect to linear time-invariant (LTI) structurally constrained controllers. Fixed modes can be found numerically for any LTI system with respect to any given control structure, using a random number generator. The existing analytical methods, however, are not capable of characterizing the fixed modes in the most general case of non-strictly proper systems with non-block diagonal (i.e., overlapping) control structure, efficiently. The notion of a decentralized overlapping fixed mode (DOFM) is introduced in this paper to address the above problem in the most general case. To this end, the knowledge of the overlapping control structure is translated into a bipartite graph, whose vertices correspond to the input and output vectors of various control channels. An efficient technique is applied to the obtained graph to identify the DOFMs of the system. It is to be noted that a system is stabilizable via an appropriate LTI decentralized overlapping controller if and only if it does not have any unstable DOFM. Moreover, it is shown how those modes which are not DOFMs can be placed freely in the complex plane using a proper LTI decentralized overlapping controller. The efficacy of this work is demonstrated through an example.\",\n \"Title: Convex Relaxation for Optimal Power Flow Problem: Mesh Networks\\nYear: 2013\\n\\nAbstract: This paper is concerned with the optimal power flow (OPF) problem. We have recently shown that a convex relaxation based on semidefinite programming (SDP) is able to find a global solution of OPF for IEEE benchmark systems, and moreover this technique is guaranteed to work over acyclic (distribution) networks. The present work studies the potential of the SDP relaxation for OPF over mesh (transmission) networks. First, we consider a simple class of cyclic systems, namely weakly-cyclic networks with cycles of size 3. We show that the success of the SDP relaxation depends on how the line capacities are modeled mathematically. More precisely, the SDP relaxation is proven to succeed if the capacity of each line is modeled in terms of bus voltage difference, as opposed to line active power, apparent power or angle difference. This result elucidates the role of the problem formulation. Our second contribution is to relate the rank of the minimum-rank solution of the SDP relaxation to the network topology. The goal is to understand how the computational complexity of OPF is related to the underlying topology of the power network. To this end, an upper bound is derived on the rank of the SDP solution, which is expected to be small in practice. A penalization method is then applied to the SDP relaxation to enforce the rank of its solution to become 1, leading to a near-optimal solution for OPF with a guaranteed optimality degree. The remarkable performance of this technique is demonstrated on IEEE systems with more than 7000 different cost functions.\",\n \"Title: Dynamic Network Energy Management via Proximal Message Passing\\nYear: 2014\\n\\nAbstract: We consider a network of devices, such as generators, fixed loads, deferrable loads, and storage devices, each with its owndynamic constraints and objective, connected by AC and DC lines. The problem is to minimize the total network objective subject tothe device and line constraints, over a given time horizon. This is a large optimization problem, with variables for consumptionor generation for each device, power flow for each line, and voltage phase angles at AC buses, in each time period. In this paperwe develop a decentralized method for solving this problem called proximal message passing. The method is iterative: At each step,each device exchanges simple messages with its neighbors in the network and then solves its own optimization problem, minimizing itsown objective function, augmented by a term determined by the messages it has received. We show that this message passing methodconverges to a solution when the device objective and constraints are convex. The method is completely decentralized, and needs noglobal coordination other than synchronizing iterations; the problems to be solved by each device can typically be solved extremelyefficiently and in parallel. The method is fast enough that even a serial implementation can solve substantial problems inreasonable time frames. We report results for several numerical experiments, demonstrating the method's speed and scaling,including the solution of a problem instance with over 10 million variables in under 50 minutes for a serial implementation;with decentralized computing, the solve time would be less than one second.\",\n \"Title: Exactness of Semidefinite Relaxations for Nonlinear Optimization Problems with Underlying Graph Structure.\\nYear: 2014\\n\\nAbstract: This work is concerned with finding a global optimization technique for a broad class of nonlinear optimization problems, including quadratic and polynomial optimization problems. The main objective of this paper is to investigate how the (hidden) structure of a given real/complex-valued optimization problem makes it easy to solve. To this end, three conic relaxations are proposed. Necessary and sufficient conditions are derived for the exactness of each of these relaxations, and it is shown that these conditions are satisfied if the optimization problem is highly structured. More precisely, the structure of the optimization problem is mapped into a generalized weighted graph, where each edge is associated with a weight set extracted from the coefficients of the optimization problem. In the real-valued case, it is shown that the relaxations are all exact if each weight set is sign definite and in addition a condition is satisfied for each cycle of the graph. It is also proved that if some of these conditions are violated, the relaxations still provide a low-rank solution for weakly cyclic graphs. In the complex-valued case, the notion of \\\"sign definite complex sets\\\" is introduced for complex weight sets. It is then shown that the relaxations are exact if each weight set is sign definite (with respect to complex numbers) and the graph is acyclic. Three other structural properties are derived for the generalized weighted graph in the complex case, each of which guarantees the exactness of some of the proposed relaxations. This result is also generalized to graphs that can be decomposed as a union of edge-disjoint subgraphs, where each subgraph has certain structural properties. As an application, it is proved that a relatively large class of real and complex optimization problems over power networks are polynomial-time solvable (with an arbitrary accuracy) due to the passivity of transmission lines and transformers.\",\n \"Title: Convex relaxation for optimal distributed control problem.\\nYear: 2014\\n\\nAbstract: This paper is concerned with the optimal distributed control (ODC) problem for linear discrete-time deterministic and stochastic systems. The objective is to design a static distributed controller with a prespecified structure that is globally optimal with respect to a quadratic cost functional. It is shown that this NP-hard problem has a quadratic formulation, which can be relaxed to a semidefinite program (SDP). If the SDP relaxation has a rank-1 solution, a globally optimal distributed controller can be recovered from this solution. By utilizing the notion of treewidth, it is proved that the nonlinearity of the ODC problem appears in such a sparse way that an SDP relaxation of this problem has a matrix solution with rank at most 3. Since the proposed SDP relaxation is computationally expensive for a large-scale system, a computationally cheap SDP relaxation is also developed with the property that its objective function indirectly penalizes the rank of the SDP solution. Various techniques are proposed to approximate a low-rank SDP solution with a rank-1 matrix, leading to near globally optimal controllers together with a bound on the optimality degree of each controller. The above results are developed for both finite-horizon and infinite-horizon ODC problems. The SDP relaxations developed in this work are exact for the design of a centralized controller, hence serving as an alternative for solving Riccati equations. The efficacy of the proposed SDP relaxations is elucidated through a case study on the distributed frequency control of power systems.\",\n \"Title: Graph-theoretic algorithms for polynomial optimization problems\\nYear: 2014\\n\\nAbstract: The objective of this tutorial paper is to study a general polynomial optimization problem using a semidefinite programming (SDP) relaxation. The first goal is to show how the underlying structure and sparsity of an optimization problem affect its computational complexity. Graph-theoretic algorithms are presented to address this problem based on the notions of low-rank optimization and matrix completion. By building on this result, it is then shown that every polynomial optimization problem admits a sparse representation whose SDP relaxation has a rank 1 or 2 solution. The implications of these results are discussed in details and their applications in decentralized control and power systems are also studied.\",\n \"Title: Low-rank solutions of matrix inequalities with applications to polynomial optimization and matrix completion problems\\nYear: 2014\\n\\nAbstract: This paper is concerned with the problem of finding a low-rank solution of an arbitrary sparse linear matrix inequality (LMI). To this end, we map the sparsity of the LMI problem into a graph. We develop a theory relating the rank of the minimum-rank solution of the LMI problem to the sparsity of its underlying graph. Furthermore, we propose two graph-theoretic convex programs to obtain a low-rank solution. The first convex optimization needs a tree decomposition of the sparsity graph. The second one does not rely on any computationally-expensive graph analysis and is always polynomial-time solvable. The results of this work can be readily applied to three separate problems of minimum-rank matrix completion, conic relaxation for polynomial optimization, and affine rank minimization. The results are finally illustrated on two applications of optimal distributed control and nonlinear optimization for electrical networks.\",\n \"Title: LQ robust controllers for polynomially uncertain systems\\nYear: 2008\\n\\nAbstract: This paper is concerned with the LQ optimal robust control of discrete-time LTI systems with uncertainties belonging to a semi-algebraic set. Given a prescribed cost function, the problem of designing a gain-scheduled static controller, whose gain depends polynomially on the uncertain parameters is formulated as a SOS problem. This indeed requires solving two hierarchies of SDP problems, which may in turn introduce high computational burden, and hence complicate the optimal robust controller design. To bypass this barrier, an alternative approach is developed which is much less involved, at the cost of obtaining a near-optimal controller (as opposed to an optimal one). The efficacy of this work is elucidated in two numerical examples.\",\n \"Title: Complexity of checking the existence of a stabilizing decentralized controller\\nYear: 2009\\n\\nAbstract: Given an interconnected system, this paper is concerned with the time complexity of verifying if any given unrepeated mode of the system is a decentralized fixed mode (DFM). It is shown that checking the decentralized fixedness of any distinct mode is tantamount to testing the strong connectivity of a digraph formed based on the system. It is subsequently proved that the time complexity of this decision problem using the proposed approach is the same as the complexity of matrix multiplication. This work concludes that the identification of distinct decentralized fixed modes (by means of a deterministic algorithm, rather than a randomized one) is computationally very easy, although the existing algorithms for solving this problem would wrongly imply that it is cumbersome. This paper provides not only a complexity analysis, but also an efficient algorithm for tackling the underlying problem.\",\n \"Title: On quantized consensus by means of gossip algorithm - Part I: Convergence proof\\nYear: 2009\\n\\nAbstract: This paper is concerned with the distributed averaging problem subject to a quantization constraint. Given a group of agents associated with scalar numbers, it is assumed that each pair of agents can communicate with a prescribed probability, and that the data being exchanged between them is quantized. In this part of the paper, it is proved that the stochastic gossip algorithm proposed in a recent paper leads to reaching the quantized consensus. Some important steady-state properties of the system (after reaching the consensus) are also derived. The results developed here hold true for any arbitrary quantization, provided that the tuning parameter of the gossip algorithm is chosen properly. The expected value of the convergence time is lower and upper bounded in the second part of the paper.\",\n \"Title: Pole Assignment With Improved Control Performance by Means of Periodic Feedback\\nYear: 2010\\n\\nAbstract: This technical note is concerned with the pole placement of continuous-time linear time-invariant (LTI) systems by means of LQ suboptimal periodic feedback. It is well-known that there exist infinitely many generalized sampled-data hold functions (GSHF) for any controllable LTI system to place the modes of its discrete-time equivalent model at prescribed locations. Among all such GSHFs, this technical note aims to find the one which also minimizes a given LQ performance index. To this end, the GSHF being sought is written as the sum of a particular GSHF and a homogeneous one. The particular GSHF can be readily obtained using the conventional pole-placement techniques. The homogeneous GSHF, on the other hand, is expressed as a linear combination of a finite number of functions such as polynomials, sinusoidals, etc. The problem of finding the optimal coefficients of this linear combination is then formulated as a linear matrix inequality (LMI) optimization. The procedure is illustrated by a numerical example.\",\n \"Title: Geometry of power flows in tree networks\\nYear: 2012\\n\\nAbstract: We investigate the problem of power flow and its relationship to optimization in tree networks. We show that due to the tree topology of the network, the general optimal power flow problem simplifies greatly. Our approach is to look at the injection region of the power network. The injection region is simply the set of all vectors of bus power injections that satisfy the network and operation constraints. The geometrical object of interest is the set of Pareto-optimal points of the injection region, since they are the solutions to the minimization of increasing functions. We view the injection region as a linear transformation of the higher dimensional power flow region, which is the set of all feasible power flows, one for each direction of each line. We show that if the voltage magnitudes are fixed, then the injection region becomes a product of two-bus power flow regions, one for each line in the network. Using this decomposition, we show that under the practical condition that the angle difference across each line is not too large, the set of Pareto-optimal points of the injection region remains unchanged by taking the convex hull. Therefore, the optimal power flow problem can be convexified and efficiently solved. This result improves upon earlier works since it does not make any assumptions about the active bus power constraints. We also obtain some partial results for the variable voltage magnitude case.\",\n \"Title: Solving Large-Scale Hybrid Circuit-Antenna Problems\\nYear: 2011\\n\\nAbstract: Motivated by different applications in circuits, electromagnetics, and optics, this paper is concerned with the synthesis of a particular type of linear circuit, where the circuit is associated with a control unit. The objective is to design a controller for this control unit such that certain specifications on the parameters of the circuit are satisfied. It is shown that designing a control unit in the form of a switching network is an NP-complete problem that can be formulated as a rank-minimization problem. It is then proven that the underlying design problem can be cast as a semidefinite optimization if a passive network is designed instead of a switching network. Since the implementation of a passive network may need too many components, the design of a decoupled (sparse) passive network is subsequently studied. This paper introduces a tradeoff between design simplicity and implementation complexity for an important class of linear circuits. The superiority of the developed techniques is demonstrated by different simulations. In particular, for the first time in the literature, a wavelength-size passive antenna is designed, which has an excellent beamforming capability and which can concurrently make a null in at least eight directions.\",\n \"Title: Passively Controllable Smart Antennas\\nYear: 2010\\n\\nAbstract: We recently introduced passively controllable smart (PCS) antenna systems for efficient wireless transmission, with direct applications in wireless sensor networks. A PCS antenna system is accompanied by a tunable passive controller whose adjustment at every signal transmission generates a specific radiation pattern. To reduce co-channel interference and optimize the transmitted power, this antenna can be programmed to transmit data in a desired direction in such a way that no signal is transmitted (to the far field) at pre-specified undesired directions. The controller of a PCS antenna was assumed to be centralized in our previous work, which was an impediment to its implementation. In this work, we study the design of PCS antenna systems under decentralized controllers, which are both practically implementable and cost efficient. The PCS antenna proposed here is made of one active element and its programming needs solving second-order-cone optimizations. These properties differentiate a PCS antenna from the existing smart antennas, and make it possible to implement a PCS antenna on a small-sized, low-power silicon chip.\",\n \"Title: Synthesis of embedded control systems with high sampling frequencies\\nYear: 2010\\n\\nAbstract: Motivated by current technological advances in the design of real-time embedded systems, this work deals with the digital control of a continuous-time linear time-invariant (LTI) system whose output can be sampled at a high frequency. Since a typical sampled-data controller operating at a high sampling frequency needs heavy (high-precision) computation to alleviate its sensitivity to measurement and computational errors, the objective is to design a robust hybrid controller for high-frequency applications with limited computational power. To this end, we exploit our recent results on delay-based controller design and propose a digital-control scheme that can implement every continuous-time stabilizing (LTI) controller. This robust hybrid controller, which consists of an ideal sampler, a digital controller, a number of modified second-order holds and possibly a unity feedback, can operate at arbitrarily high sampling frequencies without requiring expensive, high-precision computation. We also discuss how to find a continuous-time LTI controller satisfying prescribed design specifications so that its corresponding digital controller requires the least processing time.\",\n \"Title: Congestion control algorithms from optimal control perspective\\nYear: 2009\\n\\nAbstract: This paper is concerned with understanding the connection between the existing Internet congestion control al- gorithms and the optimal control theory. The available resource allocation controllers are mainly devised to derive the state of the system to a desired equilibrium point and, therefore, they are oblivious to the transient behavior of the closed-loop system. This work aims to investigate what dynamical functions the existing algorithms maximize (minimize). In particular, it is shown that there exist meaningful cost functionals whose minimization leads to the celebrated primal and dual congestion algorithms. An implication of this result is that a real network problem may be solved by regarding it as an optimal control problem on which some practical constraints, such as a real- time link capacity constraint, are imposed.\",\n \"Title: Quantized consensus via adaptive stochastic gossip algorithm\\nYear: 2009\\n\\nAbstract: This paper is concerned with the distributed averaging problem over a given undirected graph. To enable every vertex to compute the average of the initial numbers sitting on the vertices of the graph, the policy is to pick an edge at random and update the values on its ending vertices based on some rules, but only in terms of the quantized data being exchanged between them. Our recent paper showed that the quantized consensus is reached under a simple updating protocol which deploys a fixed tuning factor. The current paper allows the tuning factor to be time-dependent in order to achieve two goals. First, this makes it possible to study the numerical stability of the protocol with a fixed tuning factor under a small perturbation of this parameter. Furthermore, exploiting a time-varying tuning factor facilitates the implementation of the consensus protocol and pushes the steady state of the system towards an equilibrium point, as opposed to making it oscillatory. The current paper is an important extension of our recent work, which generalizes a finite-dimensional problem to an infinite-dimensional one that is more challenging in nature.\",\n \"Title: A new decentralization technique for interconnected systems\\nYear: 2009\\n\\nAbstract: This paper deals with LTI interconnected systems whose subsystems have coupled dynamics. The objective is to decentralize a given centralized controller satisfying some prescribed design specifications. More precisely, a parameterized decentralized controller is to be designed such that the state and the input of the system under the obtained decentralized controller can become arbitrarily close to those of the system under the given centralized controller, by tuning its free parameters. To this end, a two-level decentralized controller is designed, where the top level captures the dynamics of the centralized control system. The notion of structural initial value observability is introduced to design the bottom level of the decentralized controller. This method can decentralize every generic centralized controller, provided the interconnected system satisfies very mild conditions.\",\n \"Title: Utility Functionals Associated With Available Congestion Control Algorithms\\nYear: 2010\\n\\nAbstract: This paper is concerned with understanding the connection between the existing Internet congestion control algorithms and the optimal control theory. The available resource allocation controllers are mainly devised to derive the state of the system to a desired equilibrium point and, therefore, they are oblivious to the transient behavior of the closed-loop system. To take into account the real-time performance of the system, rather than merely its steady-state performance, the congestion control problem should be solved by maximizing a proper utility functional as opposed to a utility function. For this reason, this work aims to investigate what utility functionals the existing congestion control algorithms maximize. In particular, it is shown that there exist meaningful utility functionals whose maximization leads to the celebrated primal, dual and primal/dual algorithms. An implication of this result is that a real network problem may be solved by regarding it as an optimal control problem on which some practical constraints, such as a real-time link capacity constraint, are imposed.\",\n \"Title: Optimal Periodic Feedback Design For Continuous-Time Lti Systems With Constrained Control Structure\\nYear: 2007\\n\\nAbstract: This paper aims to design a high-performance controller with any predefined structure for continuous-time LTI systems. The control law employed is the generalized sampled-data hold function (GSHF), which can have any special form, e. g. polynomial, exponential, piecewise constant, etc. The GSHF is first written as a linear combination of a set of basis functions obtained in accordance with its desired form and structure. The objective is to find the coefficients of this linear combination, such that a prespecified linear-quadratic performance index is minimized. A necessary and sufficient condition for the existence of such GSHF is first obtained in the form of matrix inequality, which can be solved by using the existing methods to obtain a set of stabilizing initial values for the coefficients or to conclude the non-existence of such structurally constrained GSHF. An efficient algorithm is then presented to compute the optimal coefficients from their initial values, so that the performance index is minimized. The paper utilizes the latest developments in the area of sum-of-square polynomials. The effectiveness of the proposed method is demonstrated in two numerical examples.\",\n \"Title: Lq Suboptimal Decentralised Controllers With Disturbance Rejection Property For Hierarchical Systems\\nYear: 2008\\n\\nAbstract: This article is concerned with decentralised output regulation of hierarchical systems subject to input and output disturbances. It is assumed that the disturbance can be represented as the output of an autonomous linear time invariant (LTI) system with an unknown initial state. The primary objective is to design a decentralised controller with the property that not only does it reject the degrading effect of the disturbance on the output (to achieve a satisfactory steady-state performance), it also results in a small linear quadratic (LQ) cost function (implying a good transient behaviour). To this end, the underlying problem is treated in two phases. In the first step, a number of modified systems are defined in terms of the original system. The problem of designing an LQ centralised controller which stabilises all the modified systems and rejects the disturbance in the original system is considered, and it is shown that this centralised controller can be found efficiently by solving a linear matrix inequality (LMI) problem. In the second step, a method recently presented in the literature is exploited to decentralise the designed centralised controller. It is shown that the obtained controller satisfies the prescribed design specifications including disturbance rejection. Finally, in a more pragmatic context, the system is assumed to be subject to input delay, and a robustness analysis is carried out accordingly. Simulation results elucidate the efficacy of the proposed control law.\",\n \"Title: High-Performance Decentralized Control Design For General Interconnected Systems With Applications In Cooperative Control\\nYear: 2007\\n\\nAbstract: This paper deals with the decentralized control of an interconnected system, where each subsystem has models of all other subsystems ( subject to uncertainty). A decentralized controller is constructed based on a reference centralized controller. It is shown that when a priori knowledge of each subsystem about the other subsystems' models is exact, then the decentralized closed-loop system can perform exactly the same as its centralized counterpart. An easy-to-check necessary and sufficient condition for the internal stability of the decentralized closed-loop system is obtained. Moreover, the stability of the closed-loop system in the presence of the perturbation in the parameters of the system is investigated, and it is shown that the decentralized control system is probably more robust than its centralized counterpart. A proper cost function is then defined to evaluate the closeness of the decentralized closed-loop system to the corresponding centralized control system. This enables the designer to obtain the maximum allowable standard deviation for the modelling errors of the subsystems to achieve a satisfactorily small relative performance deviation with a sufficiently high probability. Finally, the proposed method is exploited to design a near-optimal decentralized control law with respect to a quadratic cost function, whose performance can, under certain conditions, be equal to the minimum achievable performance index corresponding to the centralized LQR control law. The effectiveness of the proposed method is demonstrated in three numerical examples.\",\n \"Title: The Theory Of Complex Systems With Applications To Smart Grid Operations\\nYear: 2016\\n\\nAbstract: The papers in this special section focus on complex systems within current smart grid operations. The existing power grids, being recognized as one of the significant engineering accomplishments, work exceptionally well for the purposes they have been designed to achieve. Enabled by the advances in sensing, communication, computation, and actuation, smart power are rapidly growing in scale, inter-connectivity, and complexity. Major paradigm shifts in power grids include departing producer-controlled structures and transforming to more decentralized and consumer-interactive ones, being more distributed in electricity generation, enhancing the coupling between the physical and cyber layers, and operating in more variable and stochastic conditions. Driven by these emerging needs, power grids are anticipated to be complex and smart networked platforms in which large volume of high-dimensional and complex data is routinely generated, exchanged, and processed for various monitoring, control, and scheduling purposes. The papers in this section cover some of the recent research in the theory of complex systems with applications to power grid operations, which present novel research contributions in all aspects of complex and large-scale systems of relevance and significance in power grids.\",\n \"Title: Theoretical guarantees for the design of near globally optimal static distributed controllers.\\nYear: 2016\\n\\nAbstract: This paper is concerned with the optimal distributed control problem for linear discrete-time deterministic and stochastic systems. The objective is to design a stabilizing static distributed controller whose performance is close to that of the optimal centralized controller (if such controller exists). In our previous work, we have developed a computational framework to transform centralized controllers into distributed ones for deterministic systems. By building on this result, we derive strong theoretical lower bounds on the optimality guarantee of the designed distributed controllers and show that the proposed mathematical framework indirectly maximizes the derived lower bound while striving to achieve a closed-loop stability. Furthermore, we extend the proposed design method to stochastic systems that are subject to input disturbance and measurement noise. The developed optimization problem has a closed-form solution (explicit formula) and can be easily deployed for large-scale systems that require low computational efforts. The proposed approach is tested on a power network and random systems to demonstrate its efficacy.\",\n \"Title: Characterization Of Rank-Constrained Feasibility Problems Via A Finite Number Of Convex Programs\\nYear: 2016\\n\\nAbstract: In this paper, the rank-constrained matrix feasibility problem is considered, where an unknown positive semidefinite (PSD) matrix is to be found based on a set of linear specifications. First, we consider a scenario for which the number of given linear specifications is at least equal to the dimension of the corresponding space of rank-constrained matrices. Given a nominal symmetric and PSD matrix, we design a convex program with the property that every arbitrary matrix could be recovered by this convex program based on its specifications if: i) the unknown matrix has the same size and rank as the nominal matrix, and ii) the distance between the nominal and unknown matrices is less than a positive constant number. It is also shown that if the number of specifications is nearly doubled, then it is possible to recover all rank constrained PSD matrices through a finite number of convex programs. The results of this paper are demonstrated on many randomly generated matrices.\",\n \"Title: Power System State Estimation With A Limited Number Of Measurements\\nYear: 2016\\n\\nAbstract: This paper is concerned with the power system state estimation (PSSE) problem, which aims to find the unknown operating point of a power network based on a given set of measurements. The measurements of the PSSE problem are allowed to take any arbitrary combination of nodal active powers, nodal reactive powers, nodal voltage magnitudes and line flows. This problem is non-convex and NP-hard in the worst case. We develop a set of convex programs with the property that they all solve the non-convex PSSE problem in the case of noiseless measurements as long as the voltage angles are relatively small. This result is then extended to a general PSSE problem with noisy measurements, and an upper bound on the estimation error is derived. The objective function of each convex program developed in this paper has two terms: one accounting for the non-convexity of the power flow equations and another one for estimating the noise levels. The proposed technique is demonstrated on the 1354-bus European network.\",\n \"Title: Power System State Estimation With Line Measurements\\nYear: 2016\\n\\nAbstract: This paper deals with the power flow (PF) and power system state estimation (PSSE) problems, which play a central role in the analysis and operation of electric power networks. The objective is to find the complex voltage at each bus of a network based on a given set of noiseless or noisy measurements. In this paper, it is assumed that at least two groups of measurements are available: (i) nodal voltage magnitudes, and (ii) one active flow per line for a subset of lines covering a spanning tree of the network. The PF feasibility problem is first cast as an optimization problem by adding a suitable quadratic objective function. Then, the semidefinite programming (SDP) relaxation technique is used to handle the inherent non-convexity of the PF problem. It is shown that as long as voltage angle differences across the lines of the network are not too large (e.g., less than 90 degrees for lossless networks), the SDP problem finds the correct PF solution. By capitalizing on this result, a penalized convex problem is designed to solve the PSSE problem. In addition to a linear term inherited from the SDP relaxation of the PF problem, a cost based on the weighted least absolute value is incorporated in the objective for fitting noisy measurements. The optimal solution of the penalized convex problem is shown to feature a dominant rank-one component formed by lifting the true state of the system. An upper bound on the estimation error is also derived, which depends on the noise power. It is shown that the estimation error reduces as the number of measurements increases. Numerical results for the 1354-bus European system are reported to corroborate the merits of the proposed convexification framework. The mathematical framework developed in this work can be used to study the PSSE problem with other types of measurements.\",\n \"Title: A Strong Semidefinite Programming Relaxation Of The Unit Commitment Problem\\nYear: 2016\\n\\nAbstract: The unit commitment (UC) problem aims to find an optimal schedule of generating units subject to the demand and operating constraints for an electricity grid. The majority of existing algorithms for the UC problem rely on solving a series of convex relaxations by means of branch-and-bound or cutting-planning methods. In this paper, we develop a strengthened semidefinite program (SDP) for the UC problem by first deriving certain valid quadratic constraints and then relaxing them to linear matrix inequalities. These valid inequalities are obtained by the multiplication of the linear constraints of the UC problem such as the flow constraints of two different lines. The performance of the proposed convex relaxation is evaluated on several instances of the UC problem. For most of the instances, globally optimal integer solutions are obtained by solving a single convex problem. Since the proposed technique leads to a large number of valid quadratic inequalities, an iterative procedure is devised to impose a small number of such valid inequalities. For the cases where the strengthened SDP does give a global integer solution, we incorporate other valid inequalities, including a set of Boolean quadric polytope constraints. The proposed relaxations are extensively tested on various IEEE power systems in simulations.\",\n \"Title: Finding Low-rank Solutions of Sparse Linear Matrix Inequalities using Convex Optimization.\\nYear: 2017\\n\\nAbstract: This paper is concerned with the problem of finding a low-rank solution of an arbitrary sparse linear matrix inequality (LMI). To this end, we map the sparsity of the LMI problem into a graph. We develop a mathematical framework to relate the rank of the minimum-rank solution of the LMI problem to the sparsity of its underlying graph. Furthermore, we propose three graph theoretic convex programs to obtain a low-rank solution. Two of these convex optimization problems are based on a tree decomposition of the sparsity graph. The third one does not rely on any computationally expensive graph analysis and is always polynomial-time solvable, at the cost of offering a milder theoretical guarantee on the rank of the obtained solution compared to the other two methods. The results of this work can be readily applied to three separate problems of minimum rank matrix completion, conic relaxation for polynomial optimization, and affine rank minimization. The results are finally illustrated on two applications of optimal distributed control and nonlinear optimization for electrical networks.\",\n \"Title: On The Convexity Of Optimal Decentralized Control Problem And Sparsity Path\\nYear: 2017\\n\\nAbstract: This paper is concerned with an important special case of the stochastic optimal decentralized control (SODC) problem, where the objective is to design a static structurally constrained controller for a stable stochastic system. This problem is non-convex and hard to solve in general. We show that if either the measurement noise covariance or the input weighting matrix is not too small, the problem is locally convex. Under such circumstances, the design of a decentralized controller with a bounded norm subject to an arbitrary sparsity pattern is naturally a convex problem. We also study the problem of designing a sparse controller using a regularization technique, where the control structure is not pre-specified but penalized in the objective function. Under some genericity assumptions, we prove that this method is able to design a decentralized controller with any arbitrary sparsity level. Although this paper is focused on stable systems, the results can be generalized to unstable systems as long as an initial stabilizing controller with a desirable structure is known a priori.\",\n \"Title: Guest Editorial Distributed Control and Efficient Optimization Methods for Smart Grid.\\nYear: 2017\\n\\nAbstract: Smart grid proactively uses the state-of-the-art technologies in communications, computing, and control to improve efficiency, reliability, sustainability, and stability of the electrical grid. In particular, distribution networks are expected to undergo dramatic changes by incorporating a large number of sensors and thousands of controllable devices such as distributed generators, batteries and f...\",\n \"Title: A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems.\\nYear: 2017\\n\\nAbstract: Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. This paper surveys the literature of distributed algorithms wi...\",\n \"Title: A semidefinite programming relaxation under false data injection attacks against power grid AC state estimation.\\nYear: 2017\\n\\nAbstract: The integration of sensing and information technology renders the power grid susceptible to cyber-attacks. To understand how vulnerable the state estimator is, we study its behavior under the worst attacks possible. A general false data injection attack (FDIA) based on the AC model is formulated, where the attacker manipulates sensor measurements to mislead the system operator to make decisions based on a falsified state. To stage such an attack, the optimization problem incorporates constraints of limited resources (allowing only a limited number of measurements to be altered), and stealth operation (ensuring the cyber hack cannot be identified by the bad data detection algorithm). Due to the nonlinear AC power flow model and combinatorial selection of compromised sensors, the problem is nonconvex and cannot be solved in polynomial time; however, it is shown that convexification of the original problem based on a semidefinite programming (SDP) relaxation and a sparsity penalty is able to recover a near-optimal solution. This represents the first study to solve the AC-based FDIA. Simulations on a 30-bus system illustrate that the proposed attack requires only sparse sensor manipulation and remains stealthy from the residual-based bad data detection mechanism. In light of the analysis, this study raises new challenges on grid defense mechanism and attack detection strategy.\",\n \"Title: A Scalable Method For Designing Distributed Controllers For Systems With Unknown Initial States\\nYear: 2017\\n\\nAbstract: The optimal distributed control (ODC) problem for linear discrete-time systems is studied in this paper. The goal is to design a static stabilizing controller that offers some optimality guarantee for the closed-loop system and yet respects an imposed communication structure. Unlike the traditional centralized control problem, the ODC problem is hard to solve in general. Recently, we have introduced an efficient and scalable algorithm to design a distributed controller whose performance is close to that of a given centralized controller, provided that the initial state of the system is known. In this work, we generalize the proposed method to systems with uncertain initial states. The objective is to make the performance of the designed distributed controller be as closely as possible to that of the optimal centralized counterpart for every initial state in the uncertainty region. It is shown that the developed method requires solving a convex problem. Strong theoretical lower bounds are provided on the optimality guarantee of the synthesized distributed controller. To illustrate the effectiveness of the proposed method, case studies on aircraft formation and frequency control of power systems are offered.\",\n \"Title: Modified Interior-Point Method For Large-And-Sparse Low-Rank Semidefinite Programs\\nYear: 2017\\n\\nAbstract: Semidefinite programs (SDPs) are powerful theoretical tools that have been studied for over two decades, but their practical use remains limited due to computational difficulties in solving large-scale, realistic-sized problems. In this paper, we describe a modified interior-point method for the efficient solution of large-and-sparse low-rank SDPs, which finds applications in graph theory, approximation theory, control theory, sum-of-squares, etc. Given that the problem data is large-and-sparse, conjugate gradients (CG) can be used to avoid forming, storing, and factoring the large and fully-dense interior-point Hessian matrix, but the resulting convergence rate is usually slow due to ill-conditioning. Our central insight is that, for a rank-k, size-n SDP, the Hessian matrix is ill-conditioned only due to a rank-nk perturbation, which can be explicitly computed using a size-n eigendecomposition. We construct a preconditioner to \\\"correct\\\" the low-rank perturbation, thereby allowing preconditioned CG to solve the Hessian equation in a few tens of iterations. This modification is incorporated within SeDuMi, and used to reduce the solution time and memory requirements of large-scale matrix-completion problems by several orders of magnitude.\",\n \"Title: Promises Of Conic Relaxations In Optimal Transmission Switching Of Power Systems\\nYear: 2017\\n\\nAbstract: This paper studies the problem of optimal transmission switching (OTS) for power systems. The goal is to identify a topology of the power grid that minimizes the cost of the system operation while satisfying the physical and operational constraints. Most of the existing methods are based on converting the OTS problem into a mixed-integer linear program (MILP), and then iteratively solving a series of convex problems. The performance of these methods depends heavily on the strength of the MILP formulation. In this paper, we first show that finding the strongest variable upper bounds to be used in the MILP formulation of the OTS problem based on the big-M method is NP-hard. Then, we propose a convex conic relaxation of the big-M MILP formulation based on a semidefinite program (SDP). Strong valid inequalities using the reformulation-linearization technique (RLT) are proposed to strengthen the SDP relaxation by multiplying different linear constraints and then convexifying them in a lifted space. We extensively evaluate the performance of the proposed method on IEEE benchmarks systems.\",\n \"Title: Spurious Critical Points In Power System State Estimation\\nYear: 2018\\n\\nAbstract: The power systems state estimation problem computes the set of complex voltage phasors given quadratic measurements using nonlinear least squares (NLS). This is a nonconvex optimization problem, so even in the absence of measurement errors, local search algorithms like Newton / Gauss-Newton can become \\\"stuck\\\" at local minima, which correspond to nonsensical estimations. In this paper, we observe that local minima cease to be an issue as redundant measurements are added. Posing state estimation as an instance of the quadratic recovery problem, we derive a bound for the distance between the true solution and the nearest spurious local minimum. We use the bound to show that critical points of the nonconvex least squares objective become increasing rare and far-away from the true solution with the addition of redundant information.\",\n \"Title: High-Performance Cooperative Distributed Model Predictive Control For Linear Systems\\nYear: 2018\\n\\nAbstract: Distributed model predictive control (DMPC) has been proven a successful method in regulating the operation of large-scale networks of constrained dynamical systems. This paper is concerned with cooperative DMPC in which the control actions of the systems are derived by the solution of a system-wide optimization problem. To exploit the merits of distributed computation algorithms, we investigate how to approximate this system-wide optimization problem by a number of loosely coupled subproblems. In this context, the main challenge is to design appropriate terminal cost-to-go functions and invariant sets that comply with the coupling pattern of the network. The goal of this paper is to present a unified framework for the synthesis of a terminal distributed controller, cost-to-go function and invariant set based on an existing optimal centralized terminal controller. We construct an objective function for the synthesis problem, which mathematically quantifies the closeness of the given centralized and distributed control systems. This objective function is formulated using the optimizer of a robust optimization problem. Conditions for global Lyapunov stability are imposed in the synthesis problem in a way that allows the terminal cost-to-go function and invariant set to admit the desired distributed structure. We illustrate the effectiveness of the proposed method on a benchmark spring-mass-damper problem.\",\n \"Title: Conic Relaxations for Power System State Estimation With Line Measurements.\\nYear: 2018\\n\\nAbstract: This paper deals with the nonconvex power system state estimation (PSSE) problem, which plays a central role in the monitoring and operation of electric power networks. Given a set of noisy measurements, PSSE aims at estimating the vector of complex voltages at all buses of the network. This is a challenging task due to the inherent nonlinearity of power flows (PFs), for which the existing methods...\",\n \"Title: Stability-Certified Reinforcement Learning: A Control-Theoretic Perspective\\nYear: 2018\\n\\nAbstract: We investigate the important problem of certifying stability of reinforcement learning policies when interconnected with nonlinear dynamical systems. We show that by regulating the partial gradients of policies, strong guarantees of robust stability can be obtained based on a proposed semidefinite programming feasibility problem. The method is able to certify a large set of stabilizing controllers by exploiting problem-specific structures; furthermore, we analyze and establish its (non)conservatism. Empirical evaluations on two decentralized control tasks, namely multi-flight formation and power system frequency regulation, demonstrate that the reinforcement learning agents can have high performance within the stability-certified parameter space and also exhibit stable learning behaviors in the long run.\",\n \"Title: A Low-Complexity Parallelizable Numerical Algorithm for Sparse Semidefinite Programming.\\nYear: 2018\\n\\nAbstract: In the past two decades, the semidefinite programming (SDP) technique has been proven to be extremely successful in the convexification of hard optimization problems appearing in graph theory, control theory, polynomial optimization theory, and many areas in engineering. In particular, major power optimization problems, such as optimal power flow, state estimation, and unit commitment, can be form...\",\n \"Title: Transformation of Optimal Centralized Controllers Into Near-Globally Optimal Static Distributed Controllers.\\nYear: 2019\\n\\nAbstract: This paper is concerned with the optimal static distributed control problem for linear discrete-time deterministic and stochastic systems. The objective is to design a stabilizing static distributed controller whose performance is close to that of the optimal centralized controller. To this end, we first consider deterministic systems, where the initial state is either given or belongs to a known ...\",\n \"Title: Convexification of generalized network flow problem\\nYear: 2019\\n\\nAbstract: This paper is concerned with the minimum-cost flow problem over an arbitrary flow network. In this problem, each node is associated with some possibly unknown injection and each line has two unknown flows at its ends that are related to each other via a nonlinear function. Moreover, all injections and flows must satisfy certain box constraints. This problem, named generalized network flow (GNF), is highly non-convex due to its nonlinear equality constraints. Under the assumption of monotonicity and convexity of the flow and cost functions, a convex relaxation is proposed, which is shown to always obtain globally optimal injections. This relaxation may fail to find optimal flows because the mapping from injections to flows is not unique in general. We show that the proposed relaxation, named convexified GNF (CGNF), obtains a globally optimal flow vector if the optimal injection vector is a Pareto point. More generally, the network can be decomposed into two subgraphs such that the lines between the subgraphs are congested at optimality and that CGNF finds correct optimal flows over all lines of one of these subgraphs. We also fully characterize the set of all globally optimal flow vectors, based on the optimal injection vector found via CGNF. In particular, we show that this solution set is a subset of the boundary of a convex set, and may include an exponential number of disconnected components. A primary application of this work is in optimization over electrical power networks.\",\n \"Title: A Convex Approximation Of Optimal Distributed Controller In Frequency Domain\\nYear: 2018\\n\\nAbstract: We study the optimal distributed control (ODC) problem and propose a design method based on the approximation of the H-2 performance using the optimal centralized controller. The designed distributed controller obeys a prescribed sparsity pattern in the frequency domain. The proposed method enables a convex approximation of the distributed controller problem, which has a closed-form solution with sub-optimality guarantees. After introducing the notion of rank-preserving weights, we give sufficient conditions for the controller to be proper, and furthermore characterize the set of controllers that can be obtained by the proposed technique via fine-tuning the algorithm parameters. The results are applied to the linear-quadratic regulator problem and to the purely decentralized case with a diagonal sparsity pattern, where certain connections to the simple methods of thresholding and averaging are discovered. Numerical examples are provided to demonstrate the effectiveness of the developed method.\",\n \"Title: Analysis Of Semidefinite Programming Relaxation Of Optimal Power Flow For Cyclic Networks\\nYear: 2018\\n\\nAbstract: The optimal power flow (OPF) problem determines an optimal operating point of the power network that minimizes a certain objective function subject to physical and network constraints. There has been a great deal of attention in convex relaxation of the OPF problem in recent years, and it has been shown that a semidefinite programming (SDP) relaxation can solve different classes of the nonconvex OPF problem to global or near-global optimality. Although it is known that the SDP relaxation is exact for radial networks under various conditions, solving the OPF problem for cyclic networks needs further research. In this paper, we propose sufficient conditions under which the SDP relaxation is exact for special but important cyclic networks. More precisely, when the objective function is a linear function of active powers, we show that the SDP relaxation is exact for odd cycles under certain conditions. Also, the exactness of the SDP relaxation for simple cycles of size 3 and 4 is proved under different technical conditions. The existence of rank-1 or -2 SDP solutions for weakly-cyclic networks is also proved in both lossy and lossless cases. In addition, when the objective function is an increasing function of reactive powers, we prove that the SDP relaxation is exact under certain conditions. This result justifies why the sum of reactive powers acts as a low-rank-promoting term for OPF. The findings of this paper provide intuition into the behavior of SDPs for different building blocks of cyclic networks.\",\n \"Title: Conic Approximation with Provable Guarantee for Traffic Signal Offset Optimization\\nYear: 2018\\n\\nAbstract: We consider the offset optimization problem that coordinates the offsets of signalized intersections to reduce vehicle queues in large-scale signalized traffic networks. We adopt a recent approach that transforms the offset optimization problem into a complex-valued quadratically-constrained quadratic program (QCQP). Using the special structure of the QCQP, we provide a π /4-approximation algorithm to find a near-global solution based on the optimal solution of a semidefinite program (SDP) relaxation. Although large-scale SDPs are generally hard to solve, we exploit sparsity structures of traffic networks to propose a numerical algorithm that is able to efficiently solve the SDP relaxation of the offset optimization problem. The developed algorithm relies on a tree decomposition to reformulate the large-scale problem into a reduced-complexity SDP. Under the practical assumption that a real-world traffic network has a bounded treewidth, we show that the complexity of the overall algorithm scales near-linearly with the number of intersections. The results of this work, including the bounded treewidth property, are demonstrated on the Berkeley, Manhattan, and Los Angeles networks. From numerical experiments it is observed that the algorithm has a linear empirical time complexity, and the solutions of all cases achieve a near-globally optimal guarantee of more than 0.99.\",\n \"Title: Conic Optimization For Robust Quadratic Regression: Deterministic Bounds And Statistical Analysis\\nYear: 2018\\n\\nAbstract: This paper is concerned with the robust quadratic regression problem, where the goal is to find the unknown parameters (state) of a system modeled by nonconvex quadratic equations based on observational data. In this problem, a sparse subset of equations are subject to errors (noise values) of arbitrary magnitudes. We propose two techniques based on conic optimization to address this problem. The first one is a penalized conic relaxation, whereas the second one is a more complex iterative conic optimization equipped with a hard thresholding operator. We derive a deterministic bound for the penalized conic relaxation to quantify how many bad measurements the algorithm can tolerate without producing a nonzero estimation error. This bound is then analyzed for Gaussian systems, and it is proved that the proposed method allows up to a square root of the total number of measurements to be grossly erroneous. If the number of measurements is sufficiently large, we show that the iterative conic optimization method recovers the unknown state precisely even when up to a constant fraction of equations are arbitrarily wrong in the Gaussian case. The efficacy of the developed methods is demonstrated on synthetic data and a European power grid.\",\n \"Title: Control-Theoretic Analysis of Smoothness for Stability-Certified Reinforcement Learning\\nYear: 2019\\n\\nAbstract: It is critical to obtain stability certificate before deploying reinforcement learning in real-world mission-critical systems. This study justifies the intuition that smoothness (i.e., small changes in inputs lead to small changes in outputs) is an important property for stability-certified reinforcement learning from a control-theoretic perspective. The smoothness margin can be obtained by solving a feasibility problem based on semi-definite programming for both linear and nonlinear dynamical systems, and it does not need to access the exact parameters of the learned controllers. Numerical evaluation on nonlinear and decentralized frequency control for large-scale power grids demonstrates that the smoothness margin can certify stability during both exploration and deployment for (deep) neural-network policies, which substantially surpass nominal controllers in performance. The study opens up new opportunities for robust Lipschitz continuous policy learning. © 2018 IEEE.\",\n \"Title: Sparse Semidefinite Programs With Near-Linear Time Complexity\\nYear: 2018\\n\\nAbstract: Some of the strongest polynomial-time relaxations to NP-hard combinatorial optimization problems are semidefinite programs (SDPs), but their solution complexity of up to O(n (6.5) L) time and O(n(4)) memory for L accurate digits limits their use in all but the smallest problems. Given that combinatorial SDP relaxations are often sparse, a technique known as chordal conversion can sometimes reduce complexity substantially. In this paper, we describe a modification of chordal conversion that allows any general-purpose interiorpoint method to solve a certain class of sparse SDPs with a guaranteed complexity of O(n(1.5) L) time and O(n) memory. To illustrate the use of this technique, we solve the MAX k-CUT relaxation and the Lovasz Theta problem on power system models with up to n = 13659 nodes in 5 minutes, using SeDuMi v1.32 on a 1.7 GHz CPU with 16 GB of RAM. The empirical time complexity for attaining L decimal digits of accuracy is approximate to 0.001n (1.1) L seconds.\",\n \"Title: Efficient Algorithm For Large-And-Sparse Lmi Feasibility Problems\\nYear: 2018\\n\\nAbstract: Linear matrix inequalities (LMIs) play a fundamental role in robust and optimal control theory. However, their practical use remains limited, in part because their solution complexities of O(n(6.5)) time and O(n(4)) memory limit their applicability to systems containing no more than a few hundred state variables. This paper describes a Newton-PCG algorithm to efficiently solve large-and-sparse LMI feasibility problems, based on efficient log-det barriers for sparse matrices. Assuming that the data matrices share a sparsity pattern that admits a sparse Cholesky factorization, we prove that the algorithm converges in linear O(n) time and memory. The algorithm is highly efficient in practice: we solve LMI feasibility problems over power system models with as many as n = 5738 state variables in 2 minutes on a standard workstation running MATLAB.\",\n \"Title: Sharp Restricted Isometry Bounds for the Inexistence of Spurious Local Minima in Nonconvex Matrix Recovery.\\nYear: 2019\\n\\nAbstract: Nonconvex matrix recovery is known to contain no spurious local minima under a restricted isometry property (RIP) with a sufficiently small RIP constant delta. If delta is too large, however, then counterexamples containing spurious local minima are known to exist. In this paper, we introduce a proof technique that is capable of establishing sharp thresholds on delta to guarantee the inexistence of spurious local minima. Using the technique, we prove that in the case of a rank-1 ground truth, an RIP constant of delta < 1/2 is both necessary and sufficient for exact recovery from any arbitrary initial point (such as a random point). We also prove a local recovery result: given an initial point x(0) satisfying f(x(0)) <= (1 - delta)(2) f(0), any descent algorithm that converges to second-order optimality guarantees exact recovery. Keywords: matrix factorization, nonconvex optimization, Restricted Isometry Property, matrix sensing, spurious local minima\",\n \"Title: Monotonicity Between Phase Angles And Power Flow And Its Implications For The Uniqueness Of Solutions\\nYear: 2019\\n\\nAbstract: This paper establishes sufficient conditions for the uniqueness of power flow solutions in an AC power system via the monotonic relationship between real power flow and the phase angle difference. More specifically, we prove that strict monotonicity holds if the angle difference is bounded by the steady-state stability limit in a power system with a series-parallel topology, or if transmission losses are sufficiently low. In both cases, a vector of voltage phase angles can be uniquely determined (up to an absolute phase shift) given a vector of active power injections within the realizable range. The implication of this result for classical power flow analysis is that, under the conditions specified above, the problem has a unique physically realizable solution if the phasor voltage magnitudes are tightly controlled.\",\n \"Title: Power Grid AC-based State Estimation: Vulnerability Analysis Against Cyber Attacks\\nYear: 2019\\n\\nAbstract: To ensure grid efficiency and reliability, power system operators continuously monitor the operational characteristics of the grid through a critical process called state estimation (SE), which performs the task by filtering and fusing various measurements collected from grid sensors. This study analyzes the vulnerability of the key operation module, namely ac-based SE, against potential cyber attacks on data integrity, also known as false data injection attack (FDIA). A general form of FDIA can be formulated as an optimization problem, whose objective is to find a stealthy and sparse data injection vector on the sensor measurements with the aim of making the state estimate spurious and misleading. Due to the nonlinear ac measurement model and the cardinality constraint, the problem includes both continuous and discrete nonlinearities. To solve the FDIA problem efficiently, we propose a novel convexification framework based on semidefinite programming (SDP). By analyzing a globally optimal SDP solution, we delineate the “attackable region” for any given set of measurement types and grid topology, where the spurious state can be falsified by FDIA. Furthermore, we prove that the attack is stealthy and sparse, and derive performance bounds. Simulation results on various IEEE test cases indicate the efficacy of the proposed convexification approach. From the grid protection point of view, the results of this study can be used to design a security metric for the current practice against cyber attacks, redesign the bad data detection scheme, and inform proposals of grid hardening. From a theoretical point of view, the proposed framework can be used for other nonconvex problems in power systems and beyond.\",\n \"Title: On Sampling Complexity of the Semidefinite Affine Rank Feasibility Problem\\nYear: 2019\\n\\nAbstract: In this paper, we study the semidefinite affine rank feasibility problem, which consists in finding a positive semidefinite matrix of a given rank from its linear measurements. We consider the semidefinite programming relaxations of the problem with different objective functions and study their properties. In particular, we propose an analytical bound on the number of relaxations that are sufficient to solve in order to obtain a solution of a generic instance of the semidefinite affine rank feasibility problem or prove that there is no solution. This is followed by a heuristic algorithm based on semidefinite relaxation and an experimental proof of its performance on a large sample of synthetic data.\",\n \"Title: Convexification of Power Flow Equations in the Presence of Noisy Measurements\\nYear: 2019\\n\\nAbstract: This paper is concerned with the power system state estimation (PSSE) problem that aims to find the unknown operating point of a power network based on a given set of measurements. We first study the power flow (PF) problem as an important special case of PSSE, which is known to be non-convex and NP-hard in the worst case. To this end, we propose a set of semidefinite programs (SDPs) with the property that they all solve the PF problem as long as the voltage angles are relatively small. Associated with each SDP, we explicitly characterize the set of all complex voltages that can be recovered via that convex problem. As a generalization, the design of an SDP problem that recovers multiple nominal points and a neighborhood around each point is also cast as a convex program. The results are then extended to the PSSE problem, where the measurements used in the PF problem are subject to noise. A two-term objective function is employed for each convex program developed for the PSSE problem: (i) one term accounting for the non-convexity of the power flow equations, (ii) another one for estimating the noise levels. An upper bound on the estimation error is derived with respect to the noise level and the proposed techniques are demonstrated on multiple test systems, including a 9241-bus European network. Although the focus of the paper is on power networks, the developed results apply to every arbitrary state estimation problem with quadratic measurement equations.\",\n \"Title: Escaping Locally Optimal Decentralized Control Polices via Damping.\\nYear: 2020\\n\\nAbstract: We study the design of an optimal static decentralized controller with a quadratic cost and propose a variant of the homotopy continuation method using a damping technique. This method generates a series of optimal distributed control (ODC) problems via a continuous variation of the system parameters. Diverging from the classical theme of tracking a specific trajectory of locally optimal controllers for these ODC problems, we focus on the possibility of leveraging local-search algorithms to locate the globally optimal trajectory among several locally optimal controller trajectories. We analyze the continuity and asymptotic properties of the locally and globally optimal controller trajectories as the damping parameter varies. In particular, we prove that under certain conditions, there is no spurious locally optimal controller for an ODC problem with favorable control structure and a large damping parameter. As a result, the proposed method is able to locate the globally optimal trajectory with a suitable discretization in the space of the damping parameter. To demonstrate the effectiveness of this technique, it is shown that even for instances with an exponential number of connected components, damping could merge the trajectories of all local solutions to the trajectory of the global solutions. We further illustrate the convoluted behavior of the locally optimal trajectories with numerical examples on random systems.\",\n \"Title: Uniqueness of Power Flow Solutions Using Monotonicity and Network Topology\\nYear: 2021\\n\\nAbstract: This article establishes sufficient conditions for the uniqueness of AC power flow solutions via the monotonic relationship between real power flow and the phase angle difference. More specifically, we prove that the P-Θ power flow problem has at most one solution for any acyclic or GSP graph. In addition, for arbitrary cyclic power networks, we show that multiple distinct solutions cannot exist under the assumption that angle differences across the lines are bounded by some limit related to the maximal girth of the network. In these cases, a vector of voltage phase angles can be uniquely determined (up to an absolute phase shift) given a vector of real power injections within the realizable range. The implication of this result for the classical power flow analysis is that under the conditions specified above, the problem has a unique physically realizable solution if the phasor voltage magnitudes are fixed. We also introduce a series-parallel operator and show that this operator obtains a reduced and easier-to-analyze model for the power system without changing the uniqueness of power flow solutions.\",\n \"Title: Analysis of Spurious Local Solutions of Optimal Control Problems: One-Shot Optimization Versus Dynamic Programming\\nYear: 2021\\n\\nAbstract: Dynamic programming (DP) has a rich theoretical foundation and a broad range of applications, especially in the classic area of optimal control and the recent area of reinforcement learning (RL). Many optimal control problems can be solved as a single optimization problem, named one-shot optimization, or via a sequence of optimization problems using DP. However, the computation of their global optima often faces the NP-hardness issue due to the non-linearity of the dynamics and non-convexity of the cost, and thus only local optimal solutions may be obtained at best. Furthermore, in many cases arising in machine learning and model-free approaches, DP is the only viable choice, and therefore it is essential to understand when DP combined with a local search solver works. In this work, we introduce the notions of spurious local minimizers for the one-shot optimization and spurious local minimum policies for DP, and show that there is a deep connection between them. In particular, we prove that under mild conditions the DP method using local search can successfully solve the optimal control problem to global optimality if and only if the one-shot optimization is free of spurious solutions. This result paves the way to understand the performance of local search methods in optimal control and RL.\",\n \"Title: No Spurious Solutions in Non-convex Matrix Sensing: Structure Compensates for Isometry\\nYear: 2021\\n\\nAbstract: The paper is concerned with the theoretical explanation of the recent empirical success of solving the low-rank matrix sensing problem via nonconvex optimization. It is known that under an incoherence assumption (namely, RIP) on the sensing operator, the optimization problem has no spurious local minima. This assumption is too strong for real-world applications where the amount of data cannot be sufficiently high. We develop the notion of Kernel Structure Property (KSP), which can be used alone or combined with RIP in this context. KSP explains how the inherent structure of an operator contributes to the non-existence of spurious local minima. As a special case, we study sparse sensing operators that have a low-dimensional representation. Using KSP, we obtain novel necessary and sufficient conditions for no spurious solutions in matrix sensing and demonstrate their usefulness in analytical and numerical studies.\",\n \"Title: Diminishing Regret for Online Nonconvex Optimization\\nYear: 2021\\n\\nAbstract: A single nonconvex optimization is NP-hard in the worst case, and so is a sequence of nonconvex problems viewed separately. For online nonconvex optimization (ONO) problems, widely used local search algorithms are guaranteed to track a sequence of local optima, but offer no promises about global optimality. In this paper, we introduce the concept of nonconvexity regret to measure the performance of a local search method against a global optimization solver for ONO. We define the notion of depth of a global minimum, and show that memory and random explorations drive the nonconvexity regret to zero if the variability of the objective function is low compared to the depth of the global minima. We prove probabilistic guarantees on the regret bound that depend on the evolution of the landscapes of the time-varying objective functions. Then, based on the notions of missing mass and 1-occupancy set, we develop a practical algorithm that works even when there is no such information on the landscapes. The theoretical results imply that the existence of a low-complexity optimization at any arbitrary time instance of ONO can nullify the NP-hardness of the entire ONO problem. The results are verified through numerical simulations.\",\n \"Title: Smoothing Property of Load Variation Promotes Finding Global Solutions of Time-Varying Optimal Power Flow\\nYear: 2021\\n\\nAbstract: This article analyzes solution trajectories for optimal power flow (OPF) with time-varying load. Despite its nonlinearity, time-varying OPF is commonly solved every 5–15 min using local-search algorithms. Failing to obtain the globally optimal solution of power optimization problems jeopardizes the grid's reliability and causes financial and environmental issues. The objective of this article is t...\",\n \"Title: A Dual Approach to Constrained Markov Decision Processes with Entropy Regularization\\nYear: 2022\\n\\nAbstract: We study entropy-regularized constrained Markov decision processes (CMDPs) under the soft-max parameterization, in which an agent aims to maximize the entropy-regularized value function while satisfying constraints on the expected total utility. By leveraging the entropy regularization, our theoretical analysis shows that its Lagrangian dual function is smooth and the Lagrangian duality gap can be decomposed into the primal optimality gap and the constraint violation. Furthermore, we propose an accelerated dual-descent method for entropy-regularized CMDPs. We prove that our method achieves the global convergence rate (O) over tilde (1/T) for both the optimality gap and the constraint violation for entropy-regularized CMDPs. A discussion about a linear convergence rate for CMDPs with a single constraint is also provided.\",\n \"Title: Factorization Approach for Low-complexity Matrix Completion Problems: Exponential Number of Spurious Solutions and Failure of Gradient Methods\\nYear: 2022\\n\\nAbstract: Burer-Monteiro (B-M) factorization approach can efficiently solve low-rank matrix optimization problems under the Restricted Isometry Property (RIP) condition. It is natural to ask whether BM factorization-based methods can succeed on any low-rank matrix optimization problems with a low information-theoretic complexity, i.e., polynomial-time solvable problems that have a unique solution. We provide negative answer to this question. We investigate the landscape of B-M factorized polynomial-time solvable matrix completion (MC) problems, which are the most popular subclass of low-rank matrix optimization problems without the RIP condition. We construct an instance of polynomial-time solvable MC problems with exponentially many spurious local minima, which leads to the failure of most gradient-based methods. We define a new complexity metric that measures the solvability of low-rank matrix optimization problems based on B-M factorization approach. In addition, we show that more measurements can deteriorate the landscape, which further reveals the unfavorable behavior of B-M factorization.\",\n \"Title: When Does MAML Objective Have Benign Landscape?\\nYear: 2021\\n\\nAbstract: The paper studies the landscape of the optimization problem behind the Model-Agnostic Meta-Learning (MAML) algorithm. The goal of the study is to determine the global convergence of MAML on sequential decision-making tasks possessing a common structure. We investigate in what scenarios the benign optimization landscape of the underlying tasks results in a benign landscape of the corresponding MAML...\",\n \"Title: Adversarial Attacks on Computation of the Modified Policy Iteration Method\\nYear: 2021\\n\\nAbstract: Adversarial attacks on Markov decision processes (MDPs) and reinforcement learning (RL) have been studied in the literature in the context of robust learning and adversarial game theory. In this paper, we introduce a new notion of adversarial attacks on MDP and RL computation that is motivated by the emergence of edge computing. The large-scale computation of MDP and RL models in the form of value/policy iteration and Q-learning is being offloaded from agents to distributed servers, giving rise to edge reinforcement learning. By the inherently distributed nature of edge RL, the MDP/RL computation can be prone to adversarial attacks in different forms. We analyze a probabilistic model of adversarial attacks on the computation of the modified policy iteration method in which the principal contraction property of the Bellman operator is undermined with a certain probability in iterations of the policy evaluation step of the aforementioned method. This can result in luring the agent to search among suboptimal policies without improving the true values of policies. We prove that under certain conditions, the attacked modified policy iteration method can still converge to the vicinity of the optimal policy with high probability if the number of policy evaluation iterations is larger than a threshold that is logarithmic in the inverse of a desired precision. We also provide an upper bound on the number of iterations needed for the attacked modified policy iteration method to terminate, which holds with an associated confidence level.\",\n \"Title: Damping With Varying Regularization in Optimal Decentralized Control\\nYear: 2022\\n\\nAbstract: We study a homotopy continuation method for the design of an optimal static or dynamic decentralized controller to minimize a quadratic cost functional. The proposed method involves a combination of the classical local search technique in the space of control policies, a gradual damping of the system dynamics, and a gradual variation of a parameterized cost functional. A series of optimal decentralized control (ODC) problems is generated via a continuous variation of parameters. Unlike the classical homotopy literature, which focuses on tracking a specific trajectory, we study the ensemble of critical controller trajectories and show how the properties of the ensemble can be leveraged to find a globally optimal solution of the ODC problem. After guaranteeing the continuity and asymptotic properties of the proposed method, we prove that with enough damping, there is no spurious locally optimal controller for a block-diagonal control structure. This leads to a sufficient condition under which an iterative algorithm can find a global solution to a class of optimal decentralized control problems. The “damping property” introduced in this analysis is shown to be unique for general system matrices. Empirical observations are presented for instances with an exponential number of locally optimal decentralized controllers, where the developed method could find the global solution even when initialized at a poor local solution.\",\n \"Title: Uniqueness of Power Flow Solutions Using Graph-Theoretic Notions\\nYear: 2022\\n\\nAbstract: This article extends the uniqueness theory in (Park \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">et al.</i>\\n, 2021) and establishes general necessary and sufficient conditions for the uniqueness of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$P$</tex-math></inline-formula>\\n–\\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$\\\\Theta$</tex-math></inline-formula>\\n power flow solutions in an AC power system using some properties of the monotone regime and the power network topology. We show that the necessary and sufficient conditions can lead to tighter sufficient conditions for the uniqueness in several special cases. Our results are based on the existing notion of maximal girth and our new notion of maximal eye. Moreover, we develop a series–parallel reduction method and search-based algorithms for computing the maximal eye and the maximal girth, which are necessary for the uniqueness analysis. Reduction to a single line using the proposed reduction method is guaranteed for 2-vertex-connected series–parallel graphs. The relations between the parameters of the network before and after reduction are obtained. It is verified on real-world networks that the computation of the maximal eye can be reduced to the analysis of a much smaller power network, while the maximal girth is computed during the reduction process.\",\n \"Title: Role of sparsity and structure in the optimization landscape of non-convex matrix sensing\\nYear: 2022\\n\\nAbstract: In this work, we study the optimization landscape of the non-convex matrix sensing problem that is known to have many local minima in the worst case. Since the existing results are related to the notion of restricted isometry property (RIP) that cannot directly capture the underlying structure of a given problem, they can hardly be applied to real-world problems where the amount of data is not exorbitantly high. To address this issue, we develop the notion of kernel structure property to obtain necessary and sufficient conditions for the inexistence of spurious local solutions for any class of matrix sensing problems over a given search space. This notion precisely captures the underlying sparsity and structure of the problem, based on tools in conic optimization. We simplify the conditions for a certain class of problems to show their satisfaction and apply them to data analytics for power systems.\",\n \"Title: On the Connectivity Properties of Feasible Regions of Optimal Decentralized Control Problems\\nYear: 2022\\n\\nAbstract: The optimal decentralized control (ODC) is an NP-hard problem with many applications in real-world systems. There is a recent trend of using local search algorithms for solving optimal control problems. However, the effectiveness of these methods depends on the connectivity property of the feasible region of the underlying optimization problem. In this article, for ODC problems with static controllers, we develop a novel criterion for certifying the connectivity of the feasible region in the case where the input and output matrices of the system dynamics are identity matrices. This criterion can be checked via an efficient algorithm, and it is used to prove that the number of communication networks leading to connected feasible regions is greater than a square root of the exponential number of possible communication networks (named patterns). For ODC problems with dynamic controllers, we prove that under certain mild conditions, the closure of the feasible region is always connected after some parameterization, for general communication networks and system dynamics.\",\n \"Title: On the Global Optimum Convergence of Momentum-based Policy Gradient\\nYear: 2022\\n\\nAbstract: Policy gradient (PG) methods are popular and efficient for large-scale reinforcement learning due to their relative stability and incremental nature. In recent years, the empirical success of PG methods has led to the development of a theoretical foundation for these methods. In this work, we generalize this line of research by establishing the first set of global convergence results of stochastic PG methods with momentum terms, which have been demonstrated to be efficient recipes for improving PG methods. We study both the soft-max and the Fishernon-degenerate policy parametrizations, and show that adding a momentum term improves the global optimality sample complexities of vanilla PG methods by (O) over tilde(epsilon(-1.5)) and (O) over tilde(epsilon(-1)), respectively, where epsilon > 0 is the target tolerance. Our results for the generic Fishernon-degenerate policy parametrizations also provide the first single-loop and finite-batch PG algorithm achieving an (O) over tilde (epsilon(-3)) global optimality sample complexity. Finally, as a byproduct, our analyses provide general tools for deriving the global convergence rates of stochastic PG methods, which can be readily applied and extended to other PG estimators under the two parametrizations.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":88,"string":"88"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":48,"string":"48"}}},{"rowIdx":49,"cells":{"question_id":{"kind":"string","value":"Cecilia Mascolo"},"question":{"kind":"string","value":"Generate an abstract for the title \"GeOpps: Geographical Opportunistic Routing for Vehicular Networks\" using the following items: 1. Vehicular networks \n2. Hybrid delay tolerant network \n3. Opportunistic forwarding protocol \n4. Mobility patterns \n5. Geographical routing protocols"},"answer":{"kind":"string","value":"Vehicular networks can be seen as an example of hybrid delay tolerant network where a mixture of infostations and vehicles can be used to geographically route the information messages to the right location. In this paper we present a forwarding protocol which exploits both the opportunistic nature and the inherent characteristics of the vehicular network in terms of mobility patterns and encounters, and the geographical information present in navigator systems of vehicles. We also report about our evaluation of the protocol over a simulator using realistic vehicular traces and in comparison with other geographical routing protocols."},"correct_answer":{"kind":"string","value":"Vehicular networks can be seen as an example of hybrid delay tolerant network where a mixture of infostations and vehicles can be used to geographically route the information messages to the right location. In this paper we present a forwarding protocol which exploits both the opportunistic nature and the inherent characteristics of the vehicular network in terms of mobility patterns and encounters, and the geographical information present in navigator systems of vehicles. We also report about our evaluation of the protocol over a simulator using realistic vehicular traces and in comparison with other geographical routing protocols."},"documents":{"kind":"list like","value":["Title: Mobile Computing Middleware\nYear: 2002\n\nAbstract: Recent advances in wireless networking technologies and the growing success of mobile computing devices, such as laptop computers, third generation mobile phones, personal digital assistants, watches and the like, are enabling new classes of applications that present challeng- ing problems to designers. Mobile devices face temporary loss of network connectivity when they move; they are likely to have scarce resources, such as low battery power, slow CPU speed and little memory; they are required to react to frequent and unannounced changes in the environ- ment, such as high variability of network bandwidth, and in the resources availability. To support designers building mobile applications, research in the field of middleware systems has proliferated. Middleware aims at facilitating communication and coordination of distributed components, concealing complexity raised by mobility from application engineers as much as possible. In this survey, we examine characteristics of mobile distributed systems and distinguish them from their fixed counterpart. We introduce a framework and a categorisation of the various middle- ware systems designed to support mobility, and we present a detailed and comparative review of the major results reached in this field. An analysis of current trends inside the mobile middleware community and a discussion of further directions of research conclude the survey.","Title: An ad hoc mobility model founded on social network theory\nYear: 2004\n\nAbstract: Almost all work on mobile ad hoc networks relies on simulations, which, in turn, rely on realistic movement models for their credibility. Since there is a total absence of realistic data in the public domain, synthetic models for movement pattern generation must be used and the most widely used models are currently very simplistic, the focus being ease of implementation rather than soundness of foundation. Whilst it would be preferable to have models that better reflect the movement of real users, it is currently impossible to validate any movement model against real data. However, it is lazy to conclude from this that all models are equally likely to be invalid so any will do.We note that movement is strongly affected by the needs of humans to socialise in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled, and that are likely to bias their movement patterns. Thus, we propose a new mobility model that is founded on social network theory, because this has empirically been shown to be useful as a means of describing human relationships. In particular, the model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This grouping is only then mapped to a topographical space, with topography biased by the strength of social tie.We discuss the implementation of this mobility model and we evaluate emergent properties of the generated networks. In particular, we show that grouping mechanism strongly influences the probability distribution of the average degree (i.e., the average number of neighbours of a host) in the simulated network.","Title: Evaluating context information predictability for autonomic communication\nYear: 2006\n\nAbstract: Delay tolerant and mobile ad hoc networks present considerable challenges to the development of protocols and systems. In particular, the challenge of being able to cope with their variability is an important one: sometimes the rate at which these systems change in terms of context (such as topology, collocation duration and availability and quality of the local resources) is very high and these changes are unpredictable. Knowledge of context could be used to improve the performance of such systems. For example, context information may be extremely useful to make routing decisions. Some recent approaches have successfully exploited context and prediction on future context condition to improve performance, for instance in terms of delivery ratio and delay. In this paper, we present a model of predictability of context information and the design of a generic component implementing it. The component can be used to decide if (or in which measure) context is predictable. The model is based on the analysis of the time series representing the context information. In order to show how the component can be used in practice, we describe its integration in our context-aware adaptive routing (CAR) protocol","Title: Adaptive resource discovery for ubiquitous computing\nYear: 2004\n\nAbstract: The terms pervasive and ubiquitous computing are used to describe a smart space populated by hundreds of intelligent devices that are embedded in their surroundings. Characteristically, ubiquitous computing devices must blend into the background, unobtrusively collaborating to provide value-added services for users. Services are thus essential to the success of this technology and, as a result, both service discovery and service management will play a vital role in generating the revenue stream that is a prerequisite for sustainable ubiquitous deployment. On the one hand, the services provided should be evident by their richness and variety and on the other, the complexity inherent in the environment must be hidden from users. In this paper, we describe RUBI, a resource discovery framework for ubiquitous computing. RUBI represents a novel approach to resource discovery, because the primacy of the need for adaptive autonomic behaviour is established within its design.","Title: Wildlife and environmental monitoring using RFID and WSN technology\nYear: 2009\n\nAbstract: Wireless Sensor Networks enable scientists to collect information about the environment with a granularity unseen before, while providing numerous challenges to software designers. Since sensor devices are often powered by small batteries, which take considerable effort to replace, it is of major importance to use energy carefully. We present two efficient ways of extending the lifetime of such systems: 1. an adaptive duty cycling protocol and 2. an adaptive data management protocol. Further, we present some details of our deployed sensor network in Wytham Woods, Oxfordshire.","Title: Smartphones for Large-Scale Behavior Change Interventions\nYear: 2013\n\nAbstract: Equipped with cutting-edge sensing technology and high-end processors, smartphones can unobtrusively sense human behavior and deliver feedback and behavioral therapy. The authors discuss two applications for behavioral monitoring and change and present UBhave, the first holistic platform for large-scale digital behavior change intervention.","Title: The SATIN Component System-A Metamodel for Engineering Adaptable Mobile Systems\nYear: 2006\n\nAbstract: Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, and more capable. We argue that mobile systems should be able to adapt to changing requirements and execution environments. Adaptation requires the ability to reconfigure the deployed code base on a mobile device. Such reconfiguration is considerably simplified if mobile applications are component-oriented rather than monolithic blocks of code. We present the satin (System Adaptation Targeting Integrated Networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives to reconfigure the software system by dynamically transferring code. The metamodel is implemented in the satin middleware system, a component-based mobile computing middleware that uses the mobility primitives defined in the metamodel to reconfigure both itself and applications that it hosts. We demonstrate the suitability of satin in terms of lightweightedness, flexibility, and reusability for the creation of adaptable mobile systems by using it to implement, port, and evaluate a number of existing and new applications, including an active network platform developed for satellite communication at the European Space Agency. These applications exhibit different aspects of adaptation and demonstrate the flexibility of the approach and the advantages gained.","Title: Predictive Resource Scheduling in Computational Grids\nYear: 2007\n\nAbstract: The integration of clusters of computers into computational grids has recently gained the atten- tion of many computational scientists. While considerable progress has been made in building middleware and workflow tools that facilitate the sharing of compute resources, little attention has been paid to grid scheduling and load balancing techniques to reduce job waiting time. Based on a detailed analysis of usage characteristics of an existing grid that involves a large CPU cluster, we observe that grid scheduling decisions can be significantly improved if the characteristics of current usage patterns are understood and extrapolated into the future. We describe a formal framework that uses Kalman filter theory to predict future CPU resource utilisation. This ability to predict future resource utilisation forms the basis for significantly improved grid scheduling decisions. The paper describes the architecture for such a prediction and grid scheduling framework and its implementation using Condor. By way of replicated experiments we demonstrate that the prediction achieves a precision within 15-20% of the utilisation later observed and can significantly improve scheduling quality, compared to approaches that only take into account current load indicators.","Title: Characterising temporal distance and reachability in mobile and online social networks\nYear: 2010\n\nAbstract: The analysis of social and technological networks has attracted a lot of attention as social networking applications and mobile sensing devices have given us a wealth of real data. Classic studies looked at analysing static or aggregated networks, i.e., networks that do not change over time or built as the results of aggregation of information over a certain period of time. Given the soaring collections of measurements related to very large, real network traces, researchers are quickly starting to realise that connections are inherently varying over time and exhibit more dimensionality than static analysis can capture. In this paper we propose new temporal distance metrics to quantify and compare the speed (delay) of information diffusion processes taking into account the evolution of a network from a global view. We show how these metrics are able to capture the temporal characteristics of time-varying graphs, such as delay, duration and time order of contacts (interactions), compared to the metrics used in the past on static graphs. We also characterise network reachability with the concepts of in- and out-components. Then, we generalise them with a global perspective by defining temporal connected components. As a proof of concept we apply these techniques to two classes of time-varying networks, namely connectivity of mobile devices and interactions on an online social network.","Title: Writing on the clean slate: Implementing a socially-aware protocol in Haggle\nYear: 2008\n\nAbstract: Developing protocols and applications for opportunistic networking can represent a daunting task given the many aspects that must be taken into consideration, such as intermittent connectivity, smart choice among multiple interfaces and intelligent data storage. The implementation of these protocols can be based on generic layer-less communication frameworks that provide programming abstractions for the extraction and analysis of social, colocation and mobility information and allows data exchange by means of heterogeneous devices. We propose Gently, a novel fully implemented solution which combines techniques of context awareness and social knowledge to concretely solve issues related to opportunistic forwarding. More precisely, Gently is born as the combination of the Context-aware Adaptive Routing (CAR) and the socially aware LABEL protocol. We discuss the implementation of our solution on top of the layer-less Haggle framework presenting the key design choices and the lessons learnt.","Title: Collecting big datasets of human activity one checkin at a time\nYear: 2012\n\nAbstract: A variety of cutting edge applications for mobile phones exploit the availability of phone sensors to accurately infer the user activity and location to offer more effective services. To validate and evaluate these new applications, appropriate and extensive datasets are needed: in particular, large sets of traces of sensor data (accelerometer, GPS, micro- phone, etc.), labelled with corresponding user activities. So far, such traces have only been collected in short-lived, small-scale setups. The primary reason for this is the difficulty in establishing accurate ground truth information outside the laboratory. Here, we present our vision of a system for large-scale sensor data capturing, leveraging all sensors of todays smart phones, with the aim of generating a large dataset that is augmented with appropriate ground-truth information. The primary challenges that we address consider the energy cost on the mobile device and the incentives for users to keep running the system on their device for longer. We argue for leveraging the concept of the checkin - as successfully introduced in online social networks (e.g. Foursquare) - for collecting activity and context related datasets. With a checkin, a user deliberately provides a small piece of data about their behaviour while enabling the system to adjust sensing and data collection around important activities. In this work we present up2, a mobile app letting users check in to their current activity (e.g., \\\"waiting for the bus\\\", \\\"riding a bicycle\\\", \\\"having dinner\\\"). After a checkin, we use the phone's sensors (GPS, accelerometer, microphone, etc.) to gather data about the user's activity and surrounding. This makes up2 a valuable tool for research in sensor based activity detection.","Title: A node discovery service for partially mobile sensor networks\nYear: 2007\n\nAbstract: Wireless Sensor Networks (WSNs) are challenging types of networks where resources can be scarce. In particular, battery is often a very limited resource and the radio interface is the culprit for most of the energy consumption. This makes any discovery of other sensors a difficult task, less cumbersome if sensors are fixed but crucial if (some) sensors start being mobile (such as in wildlife monitoring projects with tagged animals). In this paper we propose a middleware offering node discovery for partially mobile wireless sensor networks, where fixed nodes (sinks), deployed in the environment to monitor the movement of entities, detect those patterns with low power consumption. The approach is based on various machine learning techniques which allows for learning and adapting the wake up strategy of the sinks dynamically. We also report on the evaluation of the approach through simulation and use of real movement traces.","Title: A Tale Of Many Cities: Universal Patterns In Human Urban Mobility\nYear: 2011\n\nAbstract: The advent of geographic online social networks such as Foursquare, where users voluntarily signal their current location, opens the door to powerful studies on human movement. In particular the fine granularity of the location data, with GPS accuracy down to 10 meters, and the worldwide scale of Foursquare adoption are unprecedented. In this paper we study urban mobility patterns of people in several metropolitan cities around the globe by analyzing a large set of Foursquare users. Surprisingly, while there are variations in human movement in different cities, our analysis shows that those are predominantly due to different distributions of places across different urban environments. Moreover, a universal law for human mobility is identified, which isolates as a key component the rank-distance, factoring in the number of places between origin and destination, rather than pure physical distance, as considered in some previous works. Building on our findings, we also show how a rank-based movement model accurately captures real human movements in different cities.","Title: Don't kill my ads!: balancing privacy in an ad-supported mobile application market\nYear: 2012\n\nAbstract: Application markets have revolutionized the software download model of mobile phones: third-party application developers offer software on the market that users can effortlessly install on their phones. This great step forward, however, also imposes some threats to user privacy: applications often ask for permissions that reveal private information such as the user's location, contacts and messages. While some mechanisms to prevent leaks of user privacy to applications have been proposed by the research community, these solutions fail to consider that application markets are primarily driven by advertisements that rely on accurately profiling the user. In this paper we take into account that there are two parties with conflicting interests: the user, interested in maintaining their privacy and the developer who would like to maximize their advertisement revenue through user profiling. We have conducted an extensive analysis of more than 250,000 applications in the Android market. Our results indicate that the current privacy protection mechanisms are not effective as developers and advert companies are not deterred. Therefore, we designed and implemented a market-aware privacy protection framework that aims to achieve an equilibrium between the developer's revenue and the user's privacy. The proposed framework is based on the establishment of a feedback control loop that adjusts the level of privacy protection on mobile phones, in response to advertisement generated revenue.","Title: Adapting asynchronous messaging middleware to ad hoc networking\nYear: 2004\n\nAbstract: The characteristics of mobile environments, with the possibility of frequent disconnections and fluctuating bandwidth, have forced a rethink of traditional middleware. In particular, the synchronous communication paradigms often employed in standard middleware do not appear to be particularly suited to ad hoc environments, in which not even the intermittent availability of a backbone network can be assumed. Instead, asynchronous communication seems to be a generally more suitable paradigm for such environments. Message oriented middleware for traditional systems has been developed and used to provide an asynchronous paradigm of communication for distributed systems, and, recently, also for some specific mobile computing systems. In this paper, we present our experience in designing, implementing and evaluating EMMA (Epidemic Messaging Middleware for Ad hoc networks), an adaptation of Java Message Service (JMS) for mobile ad hoc environments. We discuss in detail the design challenges and some possible solutions, showing a concrete example of the feasibility and suitability of the application of the asynchronous paradigm in this setting and outlining a research roadmap for the coming years.","Title: Exploiting reflection in mobile computing middleware\nYear: 2002\n\nAbstract: The increasing popularity of portable devices and recent advances in wireless networking technologies facilitate the engineering of new classes of applications, which present challenging problems to designers. Mobile devices face temporary and unannounced loss of network connectivity when they are moved, they are likely to have scarce resources, and they are required to react to frequent changes in the environment. To accommodate these new requirements imposed by mobility, middleware platforms for mobile computing must be capable of both deployment-time configurability and run-time reconfigurability. We illustrate how reflective techniques can be exploited by middleware designers to address these requirements. We discuss two complementary approaches: CARISMA, where reflection is used to support dynamic adaptation of middleware behaviour to changes in context, and ReMMoC, which uses reflection to accommodate heterogeneity requirements imposed by both applications and underlying device platforms.","Title: Adaptable Mobile Applications: Exploiting Logical Mobility in Mobile Computing\nYear: 2003\n\nAbstract: An increasing number of applications is being written for mobile hosts, such as laptop computers, mobile phones, PDAs etc. These applications are usually monolithic, featuring very limited interoperability and context-awareness and are usually difficult to deploy and update. Application engineers have to deal with a very dynamic set of environments that these applications are in contact with and it is becoming increasingly difficult to design an application that will be able to cater to all the user's needs in those environments. This new setting forces a shift from design-time to run-time effort in developing software systems. To solve these problems and to allow a new class of ubiquitous and adaptable applications to be built, we have designed and implemented SATIN, a middleware system that allows the flexible use of logical mobility techniques by applications running on mobile hosts which are connected to very different networks. In this paper we describe our approach and show how SATIN can be used to deploy and update applications on mobile devices easily and efficiently.","Title: Evaluating Temporal Robustness of Mobile Networks\nYear: 2013\n\nAbstract: The application of complex network models to communication systems has led to several important results: nonetheless, previous research has often neglected to take into account their temporal properties, which in many real scenarios play a pivotal role. At the same time, network robustness has come extensively under scrutiny. Understanding whether networked systems can undergo structural damage and yet perform efficiently is crucial to both their protection against failures and to the design of new applications. In spite of this, it is still unclear what type of resilience we may expect in a network which continuously changes over time. In this work, we present the first attempt to define the concept of temporal network robustness: we describe a measure of network robustness for time-varying networks and we show how it performs on different classes of random models by means of analytical and numerical evaluation. Finally, we report a case study on a real-world scenario, an opportunistic vehicular system of about 500 taxicabs, highlighting the importance of time in the evaluation of robustness. Particularly, we show how static approximation can wrongly indicate high robustness of fragile networks when adopted in mobile time-varying networks, while a temporal approach captures more accurately the system performance.","Title: Evolution of a location-based online social network: analysis and models\nYear: 2012\n\nAbstract: Connections established by users of online social networks are influenced by mechanisms such as preferential attachment and triadic closure. Yet, recent research has found that geographic factors also constrain users: spatial proximity fosters the creation of online social ties. While the effect of space might need to be incorporated to these social mechanisms, it is not clear to which extent this is true and in which way this is best achieved. To address these questions, we present a measurement study of the temporal evolution of an online location-based social network. We have collected longitudinal traces over 4 months, including information about when social links are created and which places are visited by users, as revealed by their mobile check-ins. Thanks to this fine-grained temporal information, we test and compare whether different probabilistic models can explain the observed data adopting an approach based on likelihood estimation, quantitatively comparing their statistical power to reproduce real events. We demonstrate that geographic distance plays an important role in the creation of new social connections: node degree and spatial distance can be combined in a gravitational attachment process that reproduces real traces. Instead, we find that links arising because of triadic closure, where users form new ties with friends of existing friends, and because of common focus, where connections arise among users visiting the same place, appear to be mainly driven by social factors. We exploit our findings to describe a new model of network growth that combines spatial and social factors. We extensively evaluate our model and its variations, demonstrating that it is able to reproduce the social and spatial properties observed in our traces. Our results offer useful insights for systems that take advantage of the spatial properties of online social services.","Title: On the Effectiveness of an Opportunistic Traffic Management System for Vehicular Networks\nYear: 2011\n\nAbstract: Road congestion results in a huge waste of time and productivity for millions of people. A possible way to deal with this problem is to have transportation authorities distribute traffic information to drivers, which, in turn, can decide (or be aided by a navigator) to route around congested areas. Such traffic information can be gathered by relying on static sensors placed at specific road locations (e.g., induction loops and video cameras) or by having single vehicles report their location, speed, and travel time. While the former approach has been widely exploited, the latter has come about only more recently; consequently, its potential is less understood. For this reason, in this paper, we study a realistic test case that allows the evaluation of the effectiveness of such a solution. As part of this process, (a) we designed a system that allows vehicles to crowd-source traffic information in an ad hoc manner, allowing them to dynamically reroute based on individually collected traffic information; (b) we implemented a realistic network-mobility simulator that allowed us to evaluate such a model; and (c) we performed a case study that evaluates whether such a decentralized system can help drivers to minimize trip times, which is the main focus of this paper. This study is based on traffic survey data from Portland, OR, and our results indicate that such navigation systems can indeed greatly improve traffic flow. Finally, to test the feasibility of our approach, we implemented our system and ran some real experiments at UCLA's C-Vet test bed.","Title: XMIDDLE: information sharing middleware for a mobile environment\nYear: 2002\n\nAbstract: Summary form only given. The capabilities of modern mobile devices enable new classes of applications to exploit the ability to form ad-hoc workgroups and exchange data in a very dynamic fashion. They also present, however, new challenges to application developers, related with the scarcity of resources that need to be exploited efficiently. Moreover network connectivity may be interrupted instantaneously and network bandwidth remains by orders of magnitude lower than in wired networks. To address such issues, we have designed and implemented XMIDDLE, which advances mobile computing middleware approaches by choosing a more powerful underlying data structure (XML) and by supporting offline data manipulation.","Title: Open source smartphone libraries for computational social science\nYear: 2013\n\nAbstract: The ubiquity of sensor-rich and computationally powerful smartphones makes them an ideal platform for conducting social and behavioural research. However, building sensor data collection tools remains arduous and challenging: it requires an understanding of the varying sensor programming interfaces as well as the research issues related to building sensor-sampling systems. To alleviate this problem and facilitate the development of social sensing and data collection applications, we are developing a set of open-source smartphone libraries to collect, store and transfer, and query sensor data. Furthermore, we have also developed a library that can trigger notifications based on time or sensor events to assist experience sampling methods. This paper presents these libraries' architecture, initial feedback from developers using it, and a sensing application that we built using them to study daily affect.","Title: The importance of being placefriends: discovering location-focused online communities\nYear: 2012\n\nAbstract: Discovering groups of online friends who go to the same physical places has numerous potential applications including privacy management, friend recommendation, and contact grouping as in Google+ circles. Until recently, little information was available about places visited by users of online social networking services, so community detection on the social graph could not take this into account. With the rise of services such as Foursquare, Gowalla, and Facebook Places, where users check in to named venues and share their location with their friends, we now have the right data to make this possible. In this work, we propose a way to extract place-focused communities from the social graph by annotating its edges with check-in information. Using traces from two online social networks with location sharing, we show that we can extract groups of friends who meet face-to-face, with many possible benefits for online social services.","Title: Content Source Selection in Bluetooth Networks\nYear: 2007\n\nAbstract: Large scale market penetration of electronic devices equipped with Bluetooth technology now gives the ability to share content (such as music or video clips) between members of the public in a decentralised manner. Achieved using opportunistic connections, formed when they are colocated, in environments where Internet connectivity is expensive or unreliable, such as urban buses, train rides and coffee shops. Most people have a high degree of regularity in their movements (such as a daily commute), including repeated contacts with others possessing similar seasonal movement patterns. We argue that this behaviour can be exploited in connection selection, and outline a system for the identification of long-term companions and sources that have previously provided quality content, in order to maximise the successful receipt of content files. We utilise actual traces and existing mobility models to validate our approach, and show how consideration of the colocation history and the quality of previous data transfers leads to more successful sharing of content in realistic scenarios.","Title: CAR: Context-Aware Adaptive Routing for Delay-Tolerant Mobile Networks\nYear: 2009\n\nAbstract: Most of the existing research work in mobile ad hoc networking is based on the assumption that a path exists between the sender and the receiver. On the other hand, applications of decentralised mobile systems are often characterised by network partitions. As a consequence delay tolerant networking research has received considerable attention in the recent years as a means to obviate to the gap between ad hoc network research and real applications. In this paper we present the design, implementation and evaluation of the Context-aware Adaptive Routing (CAR) protocol for delay tolerant unicast communication in intermittently connected mobile ad hoc networks. The protocol is based on the idea of exploiting nodes as carriers of messages among network partitions to achieve delivery. The choice of the best carrier is made using Kalman filter based prediction techniques and utility theory. We discuss the implementation of CAR over an opportunistic networking framework, outlining possible applications of the general principles at the basis of the proposed approach. The large scale performance of the CAR protocol are evaluated using simulations based on a social network founded mobility model, a purely random one and real traces from Dartmouth College.","Title: Visualizing Z Notation in HTML Documents\nYear: 1998\n\nAbstract: The use of the WWW as a communication medium for software engineers is limited by the lack of tools for writing, sharing, and verifying formal notations. For instance, the Z specification language has a a rich set of mathematical characters, and requires graphic-rich boxes and schemas for its specifications. It is difficult to integrate Z specifications and text on WWW pages written with the current versions of HTML, and traditional tools are not suited for the task. We present a Java-based...","Title: Managing Complex Documents Over the WWW: A Case Study for XML\nYear: 1999\n\nAbstract: The use of the World Wide Web as a communication medium for knowledge engineers and software designers is limited by the lack of tools for writing, sharing, and verifying documents written with design notations. For instance, the Z language has a rich set of mathematical characters, and requires graphic-rich boxes and schemas for structuring a specification document. It is difficult to integrate Z specifications and text on WWW pages written with HTML, and traditional tools are not suited for the task. On the other hand, a newly proposed standard for markup languages, namely XML, allows one to define any set of markup elements; hence, it is suitable for describing any kind of notation. Unfortunately, the proposed standard for rendering XML documents, namely XSL, provides for text-only (although sophisticated) rendering of XML documents, and thus it cannot be used for more complex notations. We present a Java-based tool for applying any notation to elements of XML documents. These XML documents can thus be shown on current-generation WWW browsers with Java capabilities. A complete package for displayingZ specifications has been implemented and integrated with standard text parts. Being a complete rendering engine, text parts andZ specifications can be freely intermixed, and all the standard features of XML (including HTML links and form elements) are available outside and inside Z specifications. Furthermore, the extensibility of our engine allows any additional notations to be supported and integrated with the ones we describe here.","Title: Analyzing and Refining an Architectural Style\nYear: 1997\n\nAbstract: Architectural styles have been introduced in [1] in order to classify and analyze software architectures. In that paper, Z was used as a notation to specify and study architectural styles, however some problems remained open concerning specification and analysis of their behavioral properties. In this paper we use a new operational semantics to describe and analyze an architectural style for distributed systems. We give three refinements of a "Message Router" style, useful for describing...","Title: CODEWEAVE: Exploring Fine-Grained Mobility of Code\nYear: 2004\n\nAbstract: This paper is concerned with an abstract exploration of code mobility constructs designed for use in settings where the level of granularity associated with the mobile units exhibits significant variability. Units of mobility that are both finer and coarser grained than the unit of execution are examined. To accomplish this, we take the extreme view that every line of code and every variable declaration are potentially mobile, i.e., it may be duplicated or moved from one program context to another on the same host or across the network. We also assume that complex code assemblies may move with equal ease. The result is CODEWEAVE, a model that shows how to develop new forms of code mobility, assign them precise meaning, and facilitate formal verification of programs employing them. The design of CODEWEAVE relies greatly on Mobile UNITY, a notation and proof logic for mobile computing. Mobile UNITY offers a computational milieu for examining a wide range of constructs and semantic alternatives in a clean abstract setting, i.e., unconstrained by compilation and performance considerations traditionally associated with programming language design. Ultimately, the notation offered by CODEWEAVE is given exact semantic definition by means of a direct mapping to the underlying Mobile UNITY model. The abstract and formal treatment of code mobility offered by CODEWEAVE establishes a technical foundation for examining competing proposals and for subsequent integration of some of the mobility constructs both at the language level and within middleware for mobility.","Title: Opportunistic spatio-temporal dissemination system for vehicular networks\nYear: 2007\n\nAbstract: Opportunistic dissemination protocols have potentially applications in the domain of vehicular networking, ranging from advertising to emergency/traffic/parking information spreading: one of the characteristics of vehicular networks is that they are often partitioned due to lack of continuity in connectivity among cars or limited coverage of infostations in remote areas. Most available opportunistic, or delay tolerant, networking protocols, however, fail to take into account the peculiarities of vehicular networks. This paper introduces a novel opportunistic event dissemination protocol for vehicular networks. The protocol takes into account the characteristics of these networks in order to dispatch the publications to the subscribers. Furthermore, it uses opportunistic cache and replay mechanisms to deliver the notifications to new subscribers in the area throughout the publication interval. We evaluate our approach through simulation using realistic vehicular traces. We compare our algorithm with a standard epidemic protocol, which offer the best alternative in terms of message delivery, by measuring overhead and delivery over a number of scenarios.","Title: MobiS: A Specification Language for Mobile Systems\nYear: 1999\n\nAbstract: New formal languages have been proposed for the specification of mobility aspects of systems and for understanding the recent devised technologies for mobile computing. In this paper we introduce MobiS, a specification language based on a tuple-spaces based model which specifies coordination bymultiset rewriting. We show how MobiS can be flexibly used to specify architectures containing mobile components and give formalization of some common mobility paradigms. We explore the styles we introduce showing how they model the software architecture of a \"Purchasing System\", a case study in electronic commerce.","Title: Sense and sensibility in a pervasive world\nYear: 2012\n\nAbstract: The increasing popularity of location based social services such as Facebook Places, Foursquare and Google Latitude, solicits a new trend in fusing social networking with real-world sensing. The availability of a wide range of sensing technologies in our everyday environment presents an opportunity to further enrich social networking systems with fine-grained real-world sensing. However, the introduction of passive sensing into a social networking application disrupts the traditional, user-initiated input to social services, raising both privacy and acceptability concerns. In this work we present an empirical study of the introduction of a sensor-driven social sharing application within the working environment of a research institution. Our study is based on a real deployment of a system that involves location tracking, conversation monitoring, and interaction with physical objects. By utilizing surveys, interviews and experience sampling techniques, we report on our findings regarding privacy and user experience issues, and significant factors that can affect acceptability of such services by the users. Our results suggest that such systems deliver significant value in the form of self reflection and comparison with others, while privacy concerns are raised primarily by the limited control over the way individuals are projected to their peers.","Title: Social and place-focused communities in location-based online social networks\nYear: 2013\n\nAbstract: Thanks to widely available, cheap Internet access and the ubiquity of smartphones,\nmillions of people around the world now use online location-based social networking\nservices. Understanding the structural properties of these systems and their dependence\nupon users’ habits and mobility has many potential applications, including resource\nrecommendation and link prediction. Here, we construct and characterise social and\nplace-focused graphs by using longitudinal information about declared social relationships\nand about users’ visits to physical places collected from a popular online location-based\nsocial service. We show that although the social and place-focused graphs are constructed\nfrom the same data set, they have quite different structural properties. We find that the\nsocial and location-focused graphs have different global and meso-scale structure, and in\nparticular that social and place-focused communities have negligible overlap.\nConsequently, group inference based on community detection performed on the social graph\nalone fails to isolate place-focused groups, even though these do exist in the network. By\nstudying the evolution of tie structure within communities, we show that the time period\nover which location data are aggregated has a substantial impact on the stability of\nplace-focused communities, and that information about place-based groups may be more\nuseful for user-centric applications than that obtained from the analysis of social\ncommunities alone.","Title: Applications of Temporal Graph Metrics to Real-World Networks\nYear: 2013\n\nAbstract: Real world networks exhibit rich temporal information: friends are added and removed over time in online social networks; the seasons dictate the predator-prey relationship in food webs; and the propagation of a virus depends on the network of human contacts throughout the day. Recent studies have demonstrated that static network analysis is perhaps unsuitable in the study of real world network since static paths ignore time order, which, in turn, results in static shortest paths overestimating available links and underestimating their true corresponding lengths. Temporal extensions to centrality and efficiency metrics based on temporal shortest paths have also been proposed. Firstly, we analyse the roles of key individuals of a corporate network ranked according to temporal centrality within the context of a bankruptcy scandal; secondly, we present how such temporal metrics can be used to study the robustness of temporal networks in presence of random errors and intelligent attacks; thirdly, we study containment schemes for mobile phone malware which can spread via short range radio, similar to biological viruses; finally, we study how the temporal network structure of human interactions can be exploited to effectively immunise human populations. Through these applications we demonstrate that temporal metrics provide a more accurate and effective analysis of real-world networks compared to their static counterparts.","Title: Exploiting place features in link prediction on location-based social networks\nYear: 2011\n\nAbstract: Link prediction systems have been largely adopted to recommend new friends in online social networks using data about social interactions. With the soaring adoption of location-based social services it becomes possible to take advantage of an additional source of information: the places people visit. In this paper we study the problem of designing a link prediction system for online location-based social networks. We have gathered extensive data about one of these services, Gowalla, with periodic snapshots to capture its temporal evolution. We study the link prediction space, finding that about 30% of new links are added among \"place-friends\", i.e., among users who visit the same places. We show how this prediction space can be made 15 times smaller, while still 66% of future connections can be discovered. Thus, we define new prediction features based on the properties of the places visited by users which are able to discriminate potential future links among them. Building on these findings, we describe a supervised learning framework which exploits these prediction features to predict new links among friends-of-friends and place-friends. Our evaluation shows how the inclusion of information about places and related user activity offers high link prediction performance. These results open new directions for real-world link recommendation systems on location-based social networks.","Title: Graph Metrics for Temporal Networks.\nYear: 2013\n\nAbstract: Temporal networks, i.e., networks in which the interactions among a set of elementary units change over time, can be modelled in terms of time-varying graphs, which are time-ordered sequences of graphs over a set of nodes. In such graphs, the concepts of node adjacency and reachability crucially depend on the exact temporal ordering of the links. Consequently, all the concepts and metrics proposed and used for the characterisation of static complex networks have to be redefined or appropriately extended to time-varying graphs, in order to take into account the effects of time ordering on causality. In this chapter we discuss how to represent temporal networks and we review the definitions of walks, paths, connectedness and connected components valid for graphs in which the links fluctuate over time. We then focus on temporal node-node distance, and we discuss how to characterise link persistence and the temporal small-world behaviour in this class of networks. Finally, we discuss the extension of classic centrality measures, including closeness, betweenness and spectral centrality, to the case of time-varying graphs, and we review the work on temporal motifs analysis and the definition of modularity for temporal graphs.","Title: The Call of the Crowd: Event Participation in Location-based Social Services.\nYear: 2014\n\nAbstract: Understanding the social and behavioral forces behind event participation is not only interesting from the viewpoint of social science, but also has important applications in the design of personalized event recommender systems. This paper takes advantage of data from a widely used location-based social network, Foursquare, to analyze event patterns in three metropolitan cities. We put forward several hypotheses on the motivating factors of user participation and confirm that social aspects play a major role in determining the likelihood of a user to participate in an event. While an explicit social filtering signal accounting for whether friends are attending dominates the factors, the popularity of an event proves to also be a strong attractor. Further, we capture an implicit social signal by performing random walks in a high dimensional graph that encodes the place type preferences of friends and that proves especially suited to identify relevant niche events for users. Our findings on the extent to which the various temporal, spatial and social aspects underlie users' event preferences lead us to further hypothesize that a combination of factors better models users' event interests. We verify this through a supervised learning framework. We show that for one in three users in London and one in five users in New York and Chicago it identifies the exact event the user would attend among the pool of suggestions.","Title: SociableSense: exploring the trade-offs of adaptive sampling and computation offloading for social sensing\nYear: 2011\n\nAbstract: The interactions and social relations among users in workplaces have been studied by many generations of social psychologists. There is evidence that groups of users that interact more in workplaces are more productive. However, it is still hard for social scientists to capture fine-grained data about phenomena of this kind and to find the right means to facilitate interaction. It is also difficult for users to keep track of their level of sociability with colleagues. While mobile phones offer a fantastic platform for harvesting long term and fine grained data, they also pose challenges: battery power is limited and needs to be traded-off for sensor reading accuracy and data transmission, while energy costs in processing computationally intensive tasks are high. In this paper, we propose SociableSense, a smart phones based platform that captures user behavior in office environments, while providing the users with a quantitative measure of their sociability and that of colleagues. We tackle the technical challenges of building such a tool: the system provides an adaptive sampling mechanism as well as models to decide whether to perform computation of tasks, such as the execution of classification and inference algorithms, locally or remotely. We perform several micro-benchmark tests to fine-tune and evaluate the performance of these mechanisms and we show that the adaptive sampling and computation distribution schemes balance trade-offs among accuracy, energy, latency, and data traffic. Finally, by means of a social psychological study with ten participants for two working weeks, we demonstrate that SociableSense fosters interactions among the participants and helps in enhancing their sociability.","Title: WILDSENSING: Design and deployment of a sustainable sensor network for wildlife monitoring\nYear: 2012\n\nAbstract: The increasing adoption of wireless sensor network technology in a variety of applications, from agricultural to volcanic monitoring, has demonstrated their ability to gather data with unprecedented sensing capabilities and deliver it to a remote user. However, a key issue remains how to maintain these sensor network deployments over increasingly prolonged deployments. In this article, we present the challenges that were faced in maintaining continual operation of an automated wildlife monitoring system over a one-year period. This system analyzed the social colocation patterns of European badgers (Meles meles) residing in a dense woodland environment using a hybrid RFID-WSN approach. We describe the stages of the evolutionary development, from implementation, deployment, and testing, to various iterations of software optimization, followed by hardware enhancements, which in turn triggered the need for further software optimization. We highlight the main lessons learned: the need to factor in the maintenance costs while designing the system; to consider carefully software and hardware interactions; the importance of rapid prototyping for initial deployment (this was key to our success); and the need for continuous interaction with domain scientists which allows for unexpected optimizations.","Title: A fine-grained model for code mobility\nYear: 1999\n\nAbstract: In this paper we take the extreme view that every line of code is potentially mobile, i.e., may be duplicated and/or moved from one program context to another on the same host or across the network. Our motivation is to gain a better understanding of the range of constructs and issues facing the designer of a mobile code system, in a setting that is abstract and unconstrained by compilation and performance considerations traditionally associated with programming language design. Incidental to our study is an evaluation of the expressive power of Mobile UNITY, a notation and proof logic for mobile computing.","Title: Designing mobility models based on social network theory\nYear: 2007\n\nAbstract: Validation of mobile ad hoc network protocols relies almost exclusively on simulation. The value of the validation is, therefore, highly dependent on how realistic the movement models used in the simulations are. Since there is a very limited number of available real traces in the public domain, synthetic models for movement pattern generation must be used. However, most widely used models are currently very simplistic, their focus being ease of implementation rather than soundness of foundation. Simulation results of protocols are often based on randomly generated movement patterns and, therefore, may differ considerably from those that can be obtained by deploying the system in real scenarios. Movement is strongly affected by the needs of humans to socialise or cooperate, in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled and that have been studied in social sciences for years. In this paper we propose a new mobility model founded on social network theory. The model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This clustering is then mapped to a topographical space, with movements influenced by the strength of social ties that may also change in time. We have validated our model with real traces by showing that the synthetic mobility traces are a very good approximation of human movement patterns. The impact of the adoption of the proposed algorithm on the performance of AODV and DSR is also presented and discussed.","Title: Exploiting Logical Mobility in Mobile Computing Middleware\nYear: 2002\n\nAbstract: In the past few years, we have witnessed the growth in availability of mobile computing devices, such as mobile phones, personal digital assistants (PDAs), laptop com- puters and the like, combined with the advent of new wireless networking systems, such as 802.11b, Bluetooth, and GSM/GPRS. Users of such devices demand access to networked information and services at all times and loca- tions, and, as such, encounter different networking struc- tures and topologies. The introduction and use of mobile code techniques, from the acceptance of Java applets in web pages, to the creation of mobile agent platforms has demonstrated that it is possible to create dynamic systems that support code migration. We argue that logical mo- bility over physical mobility can offer the flexibility that traditional approaches cannot, helping to provide innova- tive solutions to mobility issues.","Title: A hybrid approach for content-based publish/subscribe in vehicular networks\nYear: 2009\n\nAbstract: Content-based information dissemination is emerging as a promising tool to tackle the demands of several applications in vehicular networking, including advertising, traffic and parking notifications, x and emergency announcements. In this paper we describe a protocol for content based information dissemination in hybrid (i.e., partially structureless) vehicular networks. The protocol allows content to ''stick'' to areas where vehicles need to receive it. The vehicle's subscriptions indicate the driver's interests about types of content and are used to filter and route information to affected vehicles. The publications, generated by other vehicles or by central servers, are first routed into the area, then continuously propagated for a specified time interval. The protocol takes advantage of both the infrastructure (i.e., wireless base stations), if this exists, and the decentralised vehicle-to-vehicle communication technologies. To show the feasibility and assess the performance of our approach, we implemented and tested our framework using a small number of vehicles. Furthermore, we run a large scale simulation over a number of realistic vehicular traces based scenarios. Results show that our protocol achieves high message delivery while introducing low overhead, even in scenarios where no infrastructure is available.","Title: Centrality prediction in dynamic human contact networks\nYear: 2012\n\nAbstract: Real technological, social and biological networks evolve over time. Predicting their future topology has applications to epidemiology, targeted marketing, network reliability and routing in ad hoc and peer-to-peer networks. The key problem for such applications is usually to identify the nodes that will be in more important positions in the future. Previous researchers had used ad hoc prediction functions. In this paper, we evaluate ways of predicting a node's future importance under three important metrics, namely degree, closeness centrality, and betweenness centrality, using empirical data on human contact networks collected using mobile devices. We find that node importance is highly predictable due to both periodic and legacy effects of human social behaviour, and we design reasonable prediction functions. However human behaviour is not the same in all circumstances: the centrality of students at Cambridge is best correlated both daily and hourly, no doubt due to hourly lecture schedules, while academics at conferences exhibit rather flat closeness centrality, no doubt because conference attendees are generally trying to speak to new people at each break. This highlights the utility of having a number of different metrics for centrality in dynamic networks, so as to identify typical patterns and predict behaviour. We show that the best-performing prediction functions are 25% more accurate on average than simply using the previous centrality value. These prediction functions can be efficiently computed in linear time, and are thus practical for processing dynamic networks in real-time.","Title: Analyzing and Animating Declarative Specifications\nYear: 1996\n\nAbstract: Z is a declarative, not executable specification language. We introduce twomethods for formal analysis and testing of behavioral aspects of Z specifications.We define a chemical operational semantics, which supports an abstract executionmodel and some new logic constructs to allow the verification of dynamicproperties. We then describe a parallel animator of Z specifications which automaticallyconstructs distributed prototypes in Shared Prolog directly from arefined specification....","Title: Efficient Node Discovery in Mobile Wireless Sensor Networks\nYear: 2008\n\nAbstract: Energy is one of the most crucial aspects in real deployments of mobile sensor networks. As a result of scarce resources, the duration of most real deployments can be limited to just several days, or demands considerable maintenance efforts (e.g., in terms of battery substitution). A large portion of the energy of sensor applications is spent in node discovery as nodes need to periodically advertise their presence and be awake to discover other nodes for data exchange. The optimization of energy consumption, which is generally a hard task in fixed sensor networks, is even harder in mobile sensor networks, where the neighbouring nodes change over time.In this paper we propose an algorithm for energy efficient node discovery in sparsely connected mobile wireless sensor networks. The work takes advantage of the fact that nodes have temporal patterns of encounters and exploits these patterns to drive the duty cycling. Duty cycling is seen as a sampling process and is formulated as an optimization problem. We have used reinforcement learning techniques to detect and dynamically change the times at which a node should be awake as it is likely to encounter other nodes. We have evaluated our work using real human mobility traces, and the paper presents the performance of the protocol in this context.","Title: A shared sensor network infrastructure\nYear: 2010\n\nAbstract: An increasing number of sensor networks have been deployed to monitor a variety of conditions and situations. At the same time, more and more applications are starting to rely on the data from sensor networks to provide users with (near) real-time information and conditions. This increasing demand of users for accurate information about natural and surrounding phoenomena is creating a business case for application providers.","Title: Los Twindignados: The Rise of the Indignados Movement on Twitter\nYear: 2012\n\nAbstract: Twitter has already become an important facet of the social Web, allowing users and organizations to share their ideas and subscribe to others' updates. Notably, it has been actively used during political events such as the recent elections in Iran, Spain and the USA, or the uprisings in the Middle East, to the extent that it is claimed that revolutions will be tweeted. However such claims are yet to be empirically established. In this work we study an extensive set of millions of tweets themed around the 2011 regional and local elections in Spain and their accompanying civil unrest. Our analysis shows that mainstream political entities were overshadowed on Twitter by grassroots movements discussing alternative points of view, at both regional and national levels. By tracking temporal trends we discover an explosion of interest in the Spanish protests following the establishment of the first protest camps in Madrid. The subsequent spontaneous setting up of similar camps in almost every town in Spain was widely reported at the time, and our spatial analysis quantitatively attests that the protests were indeed widely discussed in all parts of the country. Our results suggest that online social networks serve more as media for interactive engagement between grassroots peers, rather than as platforms for politicians to attract mass attention.","Title: Components in time-varying graphs.\nYear: 2011\n\nAbstract: Real complex systems are inherently time-varying. Thanks to new communication systems and novel technologies, today it is possible to produce and analyze social and biological networks with detailed information on the time of occurrence and duration of each link. However, standard graph metrics introduced so far in complex network theory are mainly suited for static graphs, i.e., graphs in which the links do not change over time, or graphs built from time-varying systems by aggregating all the links as if they were concurrent in time. In this paper, we extend the notion of connectedness, and the definitions of node and graph components, to the case of time-varying graphs, which are represented as time-ordered sequences of graphs defined over a fixed set of nodes. We show that the problem of finding strongly connected components in a time-varying graph can be mapped into the problem of discovering the maximal-cliques in an opportunely constructed static graph, which we name the affine graph. It is, therefore, an NP-complete problem. As a practical example, we have performed a temporal component analysis of time-varying graphs constructed from three data sets of human interactions. The results show that taking time into account in the definition of graph components allows to capture important features of real systems. In particular, we observe a large variability in the size of node temporal in-and out-components. This is due to intrinsic fluctuations in the activity patterns of individuals, which cannot be detected by static graph analysis. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697996]","Title: Analysing information flows and key mediators through temporal centrality metrics\nYear: 2010\n\nAbstract: The study of influential members of human networks is an important research question in social network analysis. However, the current state-of-the-art is based on static or aggregated representation of the network topology. We argue that dynamically evolving network topologies are inherent in many systems, including real online social and technological networks: fortunately the nature of these systems is such that they allow the gathering of large quantities of finegrained temporal data on interactions amongst the network members. In this paper we propose novel temporal centrality metrics which take into account such dynamic interactions over time. Using a real corporate email dataset we evaluate the important individuals selected by means of static and temporal analysis taking two perspectives: firstly, from a semantic level, we investigate their corporate role in the organisation; and secondly, from a dynamic process point of view, we measure information dissemination and the role of information mediators. We find that temporal analysis provides a better understanding of dynamic processes and a more accurate identification of important people compared to traditional static methods.","Title: Satin: A Component Model for Mobile Self Organisation\nYear: 2004\n\nAbstract: We have recently witnessed a growing interest in self organising systems, both in research and in practice. These systems re-organise in response to new or changing conditions in the environment. The need for self organisation is often found in mobile applications; these applications are typically hosted in resource-constrained environments and may have to dynamically reorganise in response to changes of user needs, to heterogeneity and connectivity challenges, as well as to changes in the execution context and physical environment. We argue that physically mobile applications benefit from the use of self organisation primitives. We show that a component model that incorporates code mobility primitives assists in building self organising mobile systems. We present SATIN, a lightweight component model, which represents a mobile system as a set of interoperable local components. The model supports reconfiguration, by offering code migration services. We discuss an implementation of the SATIN middleware, based on the component model and evaluate our work by adapting existing open source software as SATIN components and by building and testing a system that manages the dynamic update of components on mobile hosts.","Title: EmotionSense: a mobile phones based adaptive platform for experimental social psychology research\nYear: 2010\n\nAbstract: Today's mobile phones represent a rich and powerful computing platform, given their sensing, processing and communication capabilities. Phones are also part of the everyday life of billions of people, and therefore represent an exceptionally suitable tool for conducting social and psychological experiments in an unobtrusive way. de the ability of sensing individual emotions as well as activities, verbal and proximity interactions among members of social groups. Moreover, the system is programmable by means of a declarative language that can be used to express adaptive rules to improve power saving. We evaluate a system prototype on Nokia Symbian phones by means of several small-scale experiments aimed at testing performance in terms of accuracy and power consumption. Finally, we present the results of real deployment where we study participants emotions and interactions. We cross-validate our measurements with the results obtained through questionnaires filled by the users, and the results presented in social psychological studies using traditional methods. In particular, we show how speakers and participants' emotions can be automatically detected by means of classifiers running locally on off-the-shelf mobile phones, and how speaking and interactions can be correlated with activity and location measures.","Title: Contextual dissonance: design bias in sensor-based experience sampling methods\nYear: 2013\n\nAbstract: The Experience Sampling Method (ESM) has been widely used to collect longitudinal survey data from participants; in this domain, smartphone sensors are now used to augment the context-awareness of sampling strategies. In this paper, we study the effect of ESM design choices on the inferences that can be made from participants' sensor data, and on the variance in survey responses that can be collected. In particular, we answer the question: are the behavioural inferences that a researcher makes with a trigger-defined subsample of sensor data biased by the sampling strategy's design? We demonstrate that different single-sensor sampling strategies will result in what we refer to as contextual dissonance: a disagreement in how much different behaviours are represented in the aggregated sensor data. These results are not only relevant to researchers who use the ESM, but call for future work into strategies that may alleviate the biases that we measure.","Title: Extending access point connectivity through opportunistic routing in vehicular networks\nYear: 2010\n\nAbstract: Nowadays, the navigation systems available on cars are becoming more and more sophisticated. They greatly improve the experience of drivers and passengers by enabling them to receive map and traffic updates, news feeds, advertisements, media files, etc. Unfortunately, the bandwidth available to each vehicle with the current technology is severely limited. There have been many reports on the inability of 3G networks to cope with large size file downloads, especially in dense and mobile settings. A possible alternative is provided by WiFi access points (APs) that are being installed in several countries along the main routes and in popular areas. Although this approach significantly increases the available bandwidth, it still does not provide a fully satisfactory solution due to the limited transmission range (usually a few hundred meters). In this paper we present a novel routing protocol, based on opportunistic vehicle to vehicle communication, to enable efficient multi-hop routing capabilities between mobile vehicles and APs. Unlike prior work, this protocol fully supports two- way communication, i.e., the traditional vehicle-to-AP as well as the more challenging AP-to-vehicle. We leverage the information offered by the navigation system in terms of final destination and path, to i) route packets to the closest AP and ii) to route replies back to the moving vehicle efficiently.","Title: On Nonstationarity of Human Contact Networks\nYear: 2010\n\nAbstract: The measurement and the analysis of the temporal patterns arising in human networks is of fundamental importance to many application domains including targeted advertising, opportunistic routing, resource provisioning (e.g., bandwidth allocation in infrastructured wireless networks) and, more in general, modeling of human social behavior. In this paper we present a novel and exhaustive study of the temporal dynamics of human networks and apply it to different sets of wireless network traces. We consider networks of contacts among users (i.e., peer-to-peer opportunistic networks). We show that we are able to quantify how the amount of information associated to the process evolves over time by using techniques based on time series analysis. We also demonstrate how regular patterns appear only at certain time scales: network dynamics appears nonstationary, in the sense that its statistical description is different at various time scales. These results provide a new methodology to accurately and quantitatively investigate the temporal properties of any type of human interactions and open new directions towards a better understanding of the regular nature of human social behavior.","Title: Talking Places: Modelling and Analysing Linguistic Content in Foursquare\nYear: 2012\n\nAbstract: The advent of online social media and the growing popularity of sensor-equipped mobile devices have created a vast landscape of location-aware applications and services. This goldmine of data, including temporal and spatial information of unprecedented granularity, can help researchers gain insights into the behavioural patterns of people at a global scale. Here we analyse the textual content of millions of comments published alongside Foursquare user check-ins. For this, we extend a standard topic modelling approach so that it explicitly takes into account geographic and temporal side information. The framework is applied to Foursquare data and used to detect the dominant topics in the neighbourhoods of a city. In particular, we present the most prominent topics discussed by Foursquare users in New York, London, Chicago and San Francisco. We characterize the topics' spatial coverage and temporal evolution, and we also highlight some cultural idiosyncrasies. Finally, we evaluate the novel spatio-temporal topic model quantitatively. We believe that our model may be a useful tool for social scientists and application developers.","Title: NextPlace: a spatio-temporal prediction framework for pervasive systems\nYear: 2011\n\nAbstract: Accurate and fine-grained prediction of future user location and geographical profile has interesting and promising applications including targeted content service, advertisement dissemination for mobile users, and recreational social networking tools for smart-phones. Existing techniques based on linear and probabilistic models are not able to provide accurate prediction of the location patterns from a spatio-temporal perspective, especially for long-term estimation. More specifically, they are able to only forecast the next location of a user, but not his/her arrival time and residence time, i.e., the interval of time spent in that location. Moreover, these techniques are often based on prediction models that are not able to extend predictions further in the future. In this paper we present NextPlace, a novel approach to location prediction based on nonlinear time series analysis of the arrival and residence times of users in relevant places. NextPlace focuses on the predictability of single users when they visit their most important places, rather than on the transitions between different locations. We report about our evaluation using four different datasets and we compare our forecasting results to those obtained by means of the prediction techniques proposed in the literature. We show how we achieve higher performance compared to other predictors and also more stability over time, with an overall prediction precision of up to 90% and a performance increment of at least 50% with respect to the state of the art.","Title: Analyzing the Dynamics of a Z Specification\nYear: 1996\n\nAbstract: . We present a method for analyzing the dynamics of a Z documentdescribing a non-sequential system. First a formal operationalsemantics based on the chemical metaphor is given to Z. Then, someUnity-like temporal logic constructs are defined on such a formal operationalsemantics in order to allow the specification and analysis ofdynamic and temporal properties of concurrent systems, such as safetyand liveness properties.1 IntroductionThe introduction of formal methods increased the...","Title: Pervasive Analytics and Citizen Science [Guest editors' introduction].\nYear: 2014\n\nAbstract: This special issue aims to explore critical elements of the overall design, user experience, and resulting solutions related to using pervasive computing technologies to inform our understanding of the dynamics of ourselves and our ecosystem, community, and urban landscapes. This issue not only explores pervasive technologies but also reviews practical solutions for improving citizens' health, wellbeing, and everyday lives. Careful attention is also paid to the interplay of social media within this landscape of pervasive analytics and citizen science.","Title: Reconfigurable Component-based Middleware for Networked Embedded Systems.\nYear: 2007\n\nAbstract: Next generation embedded systems will be composed of large numbers of heterogeneous devices. These will typically be resource-constrained (such as sensor motes), will use different operating systems, and will be connected through different types of network interfaces. Additionally, they may be mobile and/or form ad-hoc networks with their peers, and will need to be adaptive to changing conditions based on context-awareness. Our focus in this paper is on the provision of a middleware framework for such system environments. Our approach is based on a small and efficient ‘middleware kernel’ which supports highly modularised and customisable component-based middleware services that can be tailored for specific embedded environments, and are runtime reconfigurable to support adaptivity. These services are primarily communications-related but also address a range of other concerns including service discovery and logical mobility. In the paper we provide an overview of our approach, focusing in detail on both the middleware kernel and the services. We also discuss an application scenario in which we are currently applying and evaluating our middleware approach.","Title: Model Checking Programmable Router Configurations\nYear: 2010\n\nAbstract: Programmable networks offer the ability to customize router behaviour at run time, thus increasing flexibility of network\n administration. Programmable network routers are configured using domain-specific languages. In this paper, we describe our\n approach to defining the syntax and semantics of such a domain-specific language. The ability to evolve router programs dynamically\n creates potential for misconfigurations. By exploiting domain-specific abstractions, we are able to translate router configurations\n into Promela and validate them using the Spin model checker, thus providing reasoning support for our domain-specific language.\n To evaluate our approach we use our configuration language to express the IETF’s Differentiated Services specification and\n show that industrial-sized DiffServ router configurations can be validated using Spin on a standard PC.","Title: EMMA: Epidemic Messaging Middleware for Ad hoc networks\nYear: 2006\n\nAbstract: The characteristics of mobile environments, with the possibility of frequent disconnections and fluctuating bandwidth, have forced a rethink of traditional middleware. In particular, the synchronous communication paradigms often employed in standard middleware do not appear to be particularly suited to ad hoc environments, in which not even the intermittent availability of a backbone network can be assumed. Instead, asynchronous communication seems to be a generally more suitable paradigm for such environments. Message oriented middleware for traditional systems has been developed and used to provide an asynchronous paradigm of communication for distributed systems, and, also for some specific mobile computing systems recently. In this paper, we present our experience in designing, implementing, and evaluating Epidemic Messaging Middleware for Ad hoc networks (EMMA), an adaptation of Java Message Service (JMS) for mobile ad hoc environments, discussing in detail the design challenges and the solutions that have been adopted.","Title: SCAR: context-aware adaptive routing in delay tolerant mobile sensor networks\nYear: 2006\n\nAbstract: Sensor devices are being embedded in all sorts of items including vehicles, furniture but also animal and human bodies through health monitors and tagging techniques. The collection of the information generated by these devices is a challenging task as the data results in enormous amounts and the sensors have scarce resources (especially in terms of energy for the forwarding of the data). Fortunately, the data is often delay tolerant and its delivery to the sinks is, in most cases, not time critical.This paper tackles the problem of the delivery of mobile sensor data to sinks. We devise a Sensor Context-Aware Routing protocol (SCAR), which exploits movement and resource prediction techniques to smartly forward data towards the right direction at any point in time. In order to cope with the possibly frequent sensor faults, we also adopt a multi-path routing approach which increases the reliability.","Title: A framework for multi-region delay tolerant networking\nYear: 2008\n\nAbstract: Almost all the existing work on routing in delay tolerant networks has focussed on the problem of delivery of messages inside a single region, characterized by the same network infrastructure and namespace. However, many deployment scenarios, especially in developing regions, will probably involve routing among different regions composed of several heterogeneous types of network domains such as WiMAX or satellite networks and ad hoc networks composed of short-range radio enabled devices, like mobile phones with Bluetooth interface. In this paper, we introduce a proposal for inter-region routing based on both probabilistic and deterministic forwarding mechanisms, embedded in an architectural framework able to support it. We also compare our solution to existing approaches in delay tolerant networking, discussing the main requirements and possible solutions, and outlining the open research problems.","Title: A Random Walk around the City: New Venue Recommendation in Location-Based Social Networks\nYear: 2012\n\nAbstract: The popularity of location-based social networks available on mobile devices means that large, rich datasets that contain a mixture of behavioral (users visiting venues), social (links between users), and spatial (distances between venues) information are available for mobile location recommendation systems. However, these datasets greatly differ from those used in other online recommender systems, where users explicitly rate items: it remains unclear as to how they capture user preferences as well as how they can be leveraged for accurate recommendation. This paper seeks to bridge this gap with a three-fold contribution. First, we examine how venue discovery behavior characterizes the large check-in datasets from two different location-based social services, Foursquare and Go Walla: by using large-scale datasets containing both user check-ins and social ties, our analysis reveals that, across 11 cities, between 60% and 80% of users' visits are in venues that were not visited in the previous 30 days. We then show that, by making constraining assumptions about user mobility, state-of-the-art filtering algorithms, including latent space models, do not produce high quality recommendations. Finally, we propose a new model based on personalized random walks over a user-place graph that, by seamlessly combining social network and venue visit frequency data, obtains between 5 and 18% improvement over other models. Our results pave the way to a new approach for place recommendation in location-based social systems.","Title: The RUNES Middleware for Networked Embedded Systems and its Application in a Disaster Management Scenario\nYear: 2007\n\nAbstract: Due to the inherent nature of their heterogeneity, resource scarcity and dynamism, the provision of middleware for future networked embedded environments is a challeng- ing task. In this paper we present a middleware approach that addresses these key challenges; we also discuss its ap- plication in a realistic networked embedded environment. Our application scenario involves fire management in a road tunnel that is instrumented with networked sensor and actuator devices. These devices are able to reconfigure their behaviour and their information dissemination strate- gies as they become damaged under emergency conditions, and firefighters are able to coordinate their operations and manage sensors and actuators through dynamic reprogram- ming. Our supporting middleware is based on a two-level architecture: the foundation is a language-independent, component-based programming model that is sufficiently minimal to run on any of the devices typically found in net- worked embedded environments. Above this is a layer of software components that offer the necessary middleware functionality. Rather than providing a monolithic middle- ware \"layer', we separate orthogonal areas of middleware functionality into self-contained components that can be se- lectively and individually deployed according to current re- source constraints and application needs. Crucially, the set of such components can be updated at runtime to provide the basis of a highly dynamic and reconfigurable system.","Title: Where Businesses Thrive: Predicting the Impact of the Olympic Games on Local Retailers through Location-based Services Data.\nYear: 2014\n\nAbstract: The Olympic Games are an important sporting event with notable consequences for the general economic landscape of the host city. Traditional economic assessments focus on the aggregated impact of the event on the national income, but fail to provide micro-scale insights on why local businesses will benefit from the increased activity during the Games. In this paper we provide a novel approach to modeling the impact of the Olympic Games on local retailers by analyzing a dataset mined from a large location-based social service, Foursquare. We hypothesize that the spatial positioning of businesses as well as the mobility trends of visitors are primary indicators of whether retailers will rise their popularity during the event. To confirm this we formulate a retail winners prediction task in the context of which we evaluate a set of geographic and mobility metrics. We find that the proximity to stadiums, the diversity of activity in the neighborhood, the nearby area sociability, as well as the probability of customer flows from and to event places such as stadiums and parks are all vital factors. Through supervised learning techniques we demonstrate that the success of businesses hinges on a combination of both geographic and mobility factors. Our results suggest that location-based social networks, where crowdsourced information about the dynamic interaction of users with urban spaces becomes publicly available, present an alternative medium to assess the economic impact of large scale events in a city.","Title: A micro-economic approach to conflict resolution in mobile computing\nYear: 2002\n\nAbstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed mobile applications. These have to adapt to changes in context, such as variations in network bandwidth, exhaustion of battery power or reachability of services on other devices. We show how the construction of adaptive and context-aware mobile applications can be supported using a reflective middleware. The middleware provides software engineers with primitives to describe how context changes are handled using policies. These policies may conflict. In this paper, we classify the different types of conflicts that may arise in mobile computing. We argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which these policy conflicts can be treated. This method uses a micro-economic approach that relies on a particular type of sealed-bid auction.","Title: SenShare: transforming sensor networks into multi-application sensing infrastructures\nYear: 2012\n\nAbstract: Sensor networks are typically purpose-built, designed to support a single running application. As the demand for applications that can harness the capabilities of a sensor-rich environment increases, and the availability of sensing infrastructure put in place to monitor various quantities soars, there are clear benefits in a model where infrastructure can be shared amongst multiple applications. This model however introduces many challenges, mainly related to the management of the communication of the same application running on different network nodes, and the isolation of applications within the network. In this work we present SenShare, a platform that attempts to address the technical challenges in transforming sensor networks into open access infrastructures capable of supporting multiple co-running applications. SenShare provides a clear decoupling between the infrastructure and the running application, building on the concept of overlay networks. Each application operates in an isolated environment consisting of an in-node hardware abstraction layer, and a dedicated overlay sensor network. We further report on the deployment of SenShare within our building, which presently supports the operation of multiple sensing applications, including office occupancy monitoring and environmental monitoring.","Title: ParkSense: a smartphone based sensing system for on-street parking\nYear: 2013\n\nAbstract: Studies of automotive traffic have shown that on average 30% of traffic in congested urban areas is due to cruising drivers looking for parking. While we have witnessed a push towards sensing technologies to monitor real-time parking availability, instrumenting on-street parking throughout a city is a considerable investment. In this paper, we present ParkSense, a smartphone based sensing system that detects if a driver has vacated a parking spot. ParkSense leverages the ubiquitous Wi-Fi beacons in urban areas for sensing unparking events. It utilizes a robust Wi-Fi signature matching approach to detect driver's return to the parked vehicle. Moreover, it uses a novel approach based on the rate of change of Wi-Fi beacons to sense if the user has started driving. We show that the rate of change of the observed beacons is highly correlated with actual user speed and is a good indicator of whether a user is in a vehicle. Through empirical evaluation, we demonstrate that our approach has a significantly smaller energy footprint than traditional location sensors like GPS and Wi-Fi based positioning while still maintaining sufficient accuracy.","Title: Selective code dissemination in mobile wireless sensor networks\nYear: 2008\n\nAbstract: We present a programming model and distributed protocol to reprogram application-defined subsets of nodes in a wireless sensor network (WSN). the protocol operation is rooted in the use of social information inferred from the behavior of the individuals nodes are attached to.","Title: Track globally, deliver locally: improving content delivery networks by tracking geographic social cascades\nYear: 2011\n\nAbstract: Providers such as YouTube offer easy access to multimedia content to millions, generating high bandwidth and storage demand on the Content Delivery Networks they rely upon. More and more, the diffusion of this content happens on online social networks such as Facebook and Twitter, where social cascades can be observed when users increasingly repost links they have received from others. In this paper we describe how geographic information extracted from social cascades can be exploited to improve caching of multimedia files in a Content Delivery Network. We take advantage of the fact that social cascades can propagate in a geographically limited area to discern whether an item is spreading locally or globally. This informs cache replacement policies, which utilize this information to ensure that content relevant to a cascade is kept close to the users who may be interested in it. We validate our approach by using a novel dataset which combines social interaction data with geographic information: we track social cascades of YouTube links over Twitter and build a proof-of-concept geographic model of a realistic distributed Content Delivery Network. Our performance evaluation shows that we are able to improve cache hits with respect to cache policies without geographic and social information.","Title: XML technologies and software engineering\nYear: 2001\n\nAbstract: No abstract available.","Title: A community based mobility model for ad hoc network research\nYear: 2006\n\nAbstract: Validation of mobile ad hoc network protocols relies almost exclusively on simulation. The value of the validation is, therefore, highly dependent on how realistic the movement models used in the simulations are. Since there is a very limited number of available real traces in the public domain, synthetic models for movement pattern generation must be used. However, most widely used models are currently very simplistic, their focus being ease of implementation rather than soundness of foundation. As a consequence, simulation results of protocols are often based on randomly generated movement patterns and, therefore, may differ considerably from those that can be obtained by deploying the system in real scenarios. Movement is strongly affected by the needs of humans to socialise or cooperate, in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled and that have been studied in social sciences for years.In this paper we propose a new mobility model founded on social network theory. The model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This grouping is then mapped to a topographical space, with movements influenced by the strength of social ties that may also change in time. We have validated our model with real traces by showing that the synthetic mobility traces are a very good approximation of human movement patterns.","Title: Temporal distance metrics for social network analysis\nYear: 2009\n\nAbstract: The analysis of social and technological networks has attracted a lot of attention as social networking applications and mobile sensing devices have given us a wealth of real data. Classic studies looked at analysing static or aggregated networks, i.e., networks that do not change over time or built as the results of aggregation of information over a certain period of time. Given the soaring collections of measurements related to very large, real network traces, researchers are quickly starting to realise that connections are inherently varying over time and exhibit more dimensionality than static analysis can capture. In this paper we propose new temporal distance metrics to quantify and compare the speed (delay) of information diffusion processes taking into account the evolution of a network from a local and global view. We show how these metrics are able to capture the temporal characteristics of time-varying graphs, such as delay, duration and time order of contacts (interactions), compared to the metrics used in the past on static graphs. As a proof of concept we apply these techniques to two classes of time-varying networks, namely connectivity of mobile devices and e-mail exchanges.","Title: Epcast: Controlled Dissemination in Human-Based Wireless Networks Using Epidemic Spreading Models\nYear: 2007\n\nAbstract: Epidemics-inspired techniques have received huge attention in recent years from the distributed systems and networking communities. These algorithms and protocols rely on probabilistic message replication and redundancy to ensure reliable communication. Moreover, they have been successfully exploited to support group communication in distributed systems, broadcasting, multicasting and information dissemination in fixed and mobile networks. However, in most of the existing work, the probability of infection is determined heuristically, without relying on any analytical model. This often leads to unnecessarily high transmission overheads. In this paper we show that models of epidemic spreading in complex networks can be applied to the problem of tuning and controlling the dissemination of information in wireless ad hoc networks composed of devices carried by individuals, i.e., human-based networks. The novelty of our idea resides in the evaluation and exploitation of the structure of the underlying human network for the automatic tuning of the dissemination process in order to improve the protocol performance. We evaluate the results using synthetic mobility models and real human contacts traces.","Title: Media sharing based on colocation prediction in urban transport\nYear: 2008\n\nAbstract: People living in urban areas spend a considerable amount of time on public transport, for example, commuting to/from work. During these periods, opportunities for inter-personal networking present themselves, as many members of the public now carry electronic devices equipped with Bluetooth or other wireless technology. Using these devices, individuals can share content (e.g., music, news and video clips) with fellow travellers that are on the same train or bus. Transferring media content takes time; in order to maximise the chances of successful downloads, users should identify neighbours that possess desirable content and who will travel with them for long-enough periods. In this paper, we propose a user-centric prediction scheme that collects historical colocation information to determine the best content sources. The scheme works on the assumption that people have a high degree of regularity in their movements. We first validate this assumption on a real dataset, that consists of traces of people moving in a large city's mass transit system. We then demonstrate experimentally on these traces that our prediction scheme significantly improves communication efficiency, when compared to a memory(history)-less source selection scheme.","Title: CTG: a connectivity trace generator for testing the performance of opportunistic mobile systems\nYear: 2007\n\nAbstract: The testing of the performance of opportunistic communication protocols and applications is usually done through simulation as i) deployments are expensive and should be left to the final stage of the development process, and ii) the number of varying parameters in thesesystems is so high that it would be very hard to conduct thorough testing of all the functionality within a single deployment. Therefore, protocols and applications are often plugged into mobility simulators to test their performance; however, until recently, most of the testing has been conducted with random mobility models which do not mirror reality. Furthermore, despite disconnections playing a veryprominent role in the performance of any opportunistic mobile system, most models do not really account for it. A different approach to testing is the use of real traces of movement collected in specific domains as test cases. These cases, however, do not allow for flexible performance testing, as they are specific for a given scenario withfixed connectivity properties. In this paper we propose the Connectivity Trace Generator (CTG), a tool for the automatic generation of connectivity traces, which takes as input real mobility traces and is able to output a set of traces with similar connectivity properties, which can be used as test cases. This allows developers to investigate the impact of the variation of connectivity patterns, number of hosts, and other parameters on the protocol or application under investigation. We use a real case study (the Dartmouth campus connectivity traces) to show how CTG allows protocol developers to play with some connectivity and density parameters so to best conduct performance testing of different aspects of protocols and applications.","Title: Hoodsquare: Modeling and Recommending Neighborhoods in Location-Based Social Networks\nYear: 2013\n\nAbstract: Information garnered from activity on location-based social networks can be harnessed to characterize urban spaces and organize them into neighborhoods. We represent geographic points in the city using spatio-temporal information about Foursquare user check-ins and semantic information about places, with the goal of developing features to input into a novel neighborhood detection algorithm. The algorithm first employs a similarity metric that assesses the homogeneity of a geographic area, and then with a simple mechanism of geographic navigation, it detects the boundaries of a city's neighborhoods. The models and algorithms devised are subsequently integrated into a publicly available, map-based tool named Hood square that allows users to explore activities and neighborhoods in cities around the world. Finally, we evaluate Hood square in the context of are commendation application where user profiles are matched to urban neighborhoods. By comparing with a number of baselines, we demonstrate how Hood square can be used to accurately predict the home neighborhood of Twitter users. We also show that we are able to suggest neighborhoods geographically constrained in size, a desirable property in mobile recommendation scenarios for which geographical precision is key.","Title: Persistent content-based information dissemination in hybrid vehicular networks\nYear: 2009\n\nAbstract: Content-based information dissemination has a potential number of applications in vehicular networking, including advertising, traffic and parking notifications and emergency announcements. In this paper we describe a protocol for content based information dissemination in hybrid (i.e., partially structureless) vehicular networks. The protocol allows content to ldquostickrdquo to areas where vehicles need to receive it. The vehicle's subscriptions indicate the driver's interests about types of content and are used to filter and route information to affected vehicles. The publications, generated by other vehicles or by central servers, are first routed into the area, then continuously propagated for a specified time interval. The protocol takes advantage of both the infrastructure (i.e., wireless base stations), if this exists, and the decentralized vehicle-to-vehicle communication technologies. We evaluate our approach by simulation over a number of realistic vehicular traces based scenarios. Results show that our protocol achieves high message delivery while introducing low overhead, even in scenarios where no infrastructure is available.","Title: An XML-based Middleware for Peer-to-Peer computing\nYear: 2001\n\nAbstract: An increasing number of distributed applications will be written for mobile hosts, such as laptop computers, third generation mobile phones, personal digital assistants, watches and the like, with focus on peer-to-peer collaboration. Application engineers have to deal with a new set of problems caused by mobility, such as low bandwidth, context changes or loss of connectivity. During disconnection, independently from each others, users will typically update local replicas of shared data, possibly generated by peers. The resulting inconsistent replicas need to be reconciled upon re-connection. To support building mobile applications that use both replication and reconciliation over ad-hoc networks, we have designed XMIDDLE, a peer-to-peer middleware that targets mobile computing settings. In this paper we describe XMIDDLE and show how reflection capabilities are used to allow application engineers to influence replication and reconciliation techniques. XMIDDLE enables the transparent sharing of XML documents across heterogeneous mobile peers, allowing online and off-line access to data","Title: Far from the eyes, close on the web: impact of geographic distance on online social interactions\nYear: 2012\n\nAbstract: Online friendship connections are often not representative of social relationships or shared interest between users, but merely provide a public display of personal identity. A better picture of online social behaviour can be achieved by taking into account the intensity of communication levels between users, yielding useful insights for service providers supporting this communication. Among the several factors impacting user interactions, geographic distance might be affecting how users communicate with their friends. While spatial proximity appears influencing how people connect to each other even on the Web, the relationship between social interaction and spatial distance remains unexplored. In this work we analyse the relationship between online user interactions and geographic proximity with a detailed study of a large Spanish online social service. Our results show that while geographic distance strongly affects how social links are created, spatial proximity plays a negligible role on user interactions. These findings offer new insights on the interplay between social and spatial factors influencing online user behaviour and open new directions for future research and applications.","Title: TACO-DTN: a time-aware content-based dissemination system for delay tolerant networks\nYear: 2007\n\nAbstract: Content dissemination applications are becoming more and more popular on fixed infrastructure: in this paper we introduce TACO-DTN, a content dissemination system which, by virtue of being time-aware in terms of subscriptions and events, is appropriate for delay tolerant networks, where a number of nodes act as infostations, enjoying some form of connectivity to the backbone, and other nodes are mobile devices, reachable sometimes only through intermittent connectivity of carriers. Examples of applications benefiting from such a system could be travel information dissemination systems in large cities (exploiting infostations at bus stops) or on highways, advertisements dissemination at specific times, and information dissemination to remote villages. The approach is based on a novel concept of temporal utility of subscriptions and events. The temporal utility is used to govern the routing of the events to the right infostation (i.e., the one reached by the interested subscribers at the right time), avoiding unnecessary information transfer on slow links and the buffer management, in case buffer limitations are an issue. We give a description of our protocol and discuss its validation through simulation.","Title: Geo-spotting: mining online location-based services for optimal retail store placement\nYear: 2013\n\nAbstract: The problem of identifying the optimal location for a new retail store has been the focus of past research, especially in the field of land economy, due to its importance in the success of a business. Traditional approaches to the problem have factored in demographics, revenue and aggregated human flow statistics from nearby or remote areas. However, the acquisition of relevant data is usually expensive. With the growth of location-based social networks, fine grained data describing user mobility and popularity of places has recently become attainable. In this paper we study the predictive power of various machine learning features on the popularity of retail stores in the city through the use of a dataset collected from Foursquare in New York. The features we mine are based on two general signals: geographic, where features are formulated according to the types and density of nearby places, and user mobility, which includes transitions between venues or the incoming flow of mobile users from distant areas. Our evaluation suggests that the best performing features are common across the three different commercial chains considered in the analysis, although variations may exist too, as explained by heterogeneities in the way retail facilities attract users. We also show that performance improves significantly when combining multiple features in supervised learning algorithms, suggesting that the retail success of a business may depend on multiple factors.","Title: Distance matters: geo-social metrics for online social networks\nYear: 2010\n\nAbstract: Online Social Networks (OSNs) are increasingly becoming one of the key media of communication over the Internet. The potential of these services as the basis to gather statistics and exploit information about user behavior is appealing and, as a consequence, the number of applications developed for these purposes has been soaring. At the same time, users are now willing to share information about their location, allowing for the study of the role of geographic distance in social ties. In this paper we present a graph analysis based approach to study social networks with geographic information and new metrics to characterize how geographic distance affects social structure. We apply our analysis to four large-scale OSN datasets: our results show that there is a vast portion of users with short-distance links and that clusters of friends are often geographically close. In addition, we demonstrate that different social networking services exhibit different geo-social properties: OSNs based mainly on location-advertising largely foster local ties and clusters, while services used mainly for news and content sharing present more connections and clusters on longer distances. The results of this work can be exploited to improve many classes of systems and a potential vast number of applications, as we illustrate by means of some practical examples.","Title: Reflective Middleware Solutions for Context-Aware Applications\nYear: 2001\n\nAbstract: In this paper, we argue that middleware for wired distributed systems cannot be used in a mobile setting, as the principle of transparency that has driven their design runs counter to the new degrees of awareness imposed by mobility. We propose the marriage of reflection and metadata as a means for middleware to give applications dynamic access to information about their execution context. Finally, we describe a conceptual model that provides the basis of our reflective middleware.","Title: Evolution and sustainability of a wildlife monitoring sensor network\nYear: 2010\n\nAbstract: As sensor network technologies become more mature, they are increasingly being applied to a wide variety of applications, ranging from agricultural sensing to cattle, oceanic and volcanic monitoring. Significant efforts have been made in deploying and testing sensor networks resulting in unprecedented sensing capabilities. A key challenge has become how to make these emerging wireless sensor networks more sustainable and easier to maintain over increasingly prolonged deployments. In this paper, we report the findings from a one year deployment of an automated wildlife monitoring system for analyzing the social co-location patterns of European badgers (Meles meles) residing in a dense woodland environment. We describe the stages of its evolution cycle, from implementation, deployment and testing, to various iterations of software optimization, followed by hardware enhancements, which in turn triggered the need for further software optimization. We report preliminary descriptive analyses of a subset of the data collected, demonstrating the significant potential our system has to generate new insights into badger behavior. The main lessons learned were: the need to factor in the maintenance costs while designing the system; to look carefully at software and hardware interactions; the importance of a rapid initial prototype deployment (this was key to our success); and the need for continuous interaction with domain scientists which allows for unexpected optimizations.","Title: Performance analysis and prediction of physically mobile systems\nYear: 2007\n\nAbstract: The market of portable computational devices is expanding more and more rapidly. The systems created by the interactions of these devices among themselves and with the surrounding infrastructure result in being quite different from existing traditional systems in terms of connectivity, dynamicity and resource availability. As a consequence, existing performance evaluation and prediction techniques appear to be inadequate to the application to mobile systems. While some adaptations have been proposed for systems presenting some logical mobility (i.e., software mobility), very little has been attempted to provide useful performance prediction methodologies for physically mobile systems.In this paper we present a methodology for modeling performance of physically mobile systems: our aim is to provide guidelines for the designer of the system on how particular physical mobility patterns affect the system performance and on how these measures can be taken into account in the early stages of the system development.","Title: Selective reprogramming of mobile sensor networks through social community detection\nYear: 2010\n\nAbstract: We target application domains where the behavior of animals or humans is monitored using wireless sensor network (WSN) devices. The code on these devices is updated frequently, as scientists acquire in-field data and refine their hypotheses. Wireless reprogramming is therefore fundamental to avoid the (expensive) re-collection of the devices. Moreover, the code carried by the monitored individuals often depends on their characteristics, e.g., the behavior or preferred habitat. We propose a selective reprogramming approach that simplifies and automates the process of delivering a code update to a target subset of nodes. Target selection is expressed through constraints injected in the WSN, triggering automatic dissemination of code updates whenever verified. Update dissemination relies on a novel protocol exploiting the social behavior of the monitored individuals. We evaluate our approach through simulation, using real-world animal and human traces. The results shows that our protocol is able to capture the social network structure in a way comparable to existing offline algorithms with global knowledge while allowing runtime adaptation to community structure changes, and that existing dissemination approaches based on gossip generate up to three times more network overhead than our socially-aware dissemination.","Title: Adaptive routing for intermittently connected mobile ad hoc networks\nYear: 2005\n\nAbstract: The vast majority of mobile ad hoc networking research makes a very large assumption - that communication can only take place between nodes that are simultaneously accessible within the same connected cloud (i.e., that communication is synchronous). In reality, this assumption is likely to be a poor one, particularly for sparsely or irregularly populated environments. We present the context-aware routing (CAR) algorithm. CAR is a novel approach to the provision of asynchronous communication in partially-connected mobile ad hoc networks, based on the intelligent placement of messages. We discuss the details of the algorithm, and then present simulation results demonstrating that it is possible for nodes to exploit context information in making local decisions that lead to good delivery ratios and latencies with small overheads.","Title: Understanding robustness of mobile networks through temporal network measures\nYear: 2011\n\nAbstract: The application of complex network theory to communication systems has led to several important results. Nonetheless, previous research has often neglected to take into account their temporal properties, which in many real scenarios play a pivotal role. Mainly because of mobility, transmission delays or protocol design, a communication network should not be considered only as a static entity. At the same time, network robustness has come extensively under scrutiny. Understanding whether networked systems can undergo structural damage and yet perform efficiently is crucial to both their protection against failures and to the design of new applications. In spite of this, it is still unclear what type of resilience we may expect in a network that continuously changes over time. In this work we present the first attempt to define the concept of temporal network robustness: we describe a measure of network robustness for time-varying networks and we show how it performs on different classes of random models by means of analytical and numerical evaluation. Particularly, we show how static approximation can wrongly indicate high robustness of fragile networks when adopted in mobile time-varying networks, while a temporal approach captures more accurately the system performance.","Title: A Place-Focused Model for Social Networks in Cities\nYear: 2013\n\nAbstract: The focused organization theory of social ties proposes that the structure of human social networks can be arranged around extra-network foci, which can include shared physical spaces such as homes, workplaces, restaurants, and so on. Until now, this has been difficult to investigate on a large scale, but the huge volume of data available from online location-based social services now makes it possible to examine the friendships and mobility of many thousands of people, and to investigate the relationship between meetings at places and the structure of the social network. In this paper, we analyze a large dataset from Foursquare, the most popular online location-based social network. We examine the properties of city-based social networks, finding that they have common structural properties, and that the category of place where two people meet has very strong influence on the likelihood of their being friends. Inspired by these observations in combination with the focused organization theory, we then present a model to generate city-level social networks, and show that it produces networks with the structural properties seen in empirical data.","Title: Tracking serendipitous interactions: how individual cultures shape the office\nYear: 2014\n\nAbstract: In many work environments, serendipitous interactions between members of different groups may lead to enhanced productivity, collaboration and knowledge dissemination. Two factors that may have an influence on such interactions are cultural differences between individuals in highly multicultural workplaces, and the layout and physical spaces of the workplace itself. In this work, we investigate how these two factors may facilitate or hinder inter-group interactions in the workplace. We analyze traces collected using wearable electronic badges to capture face-to-face interactions and mobility patterns of employees in a research laboratory in the UK. We observe that those who interact with people of different roles tend to come from collectivist cultures that value relationships and where people tend to be comfortable with social hierarchies, and that some locations in particular are more likely to host serendipitous interactions, knowledge that could be used by organizations to enhance communication and productivity.","Title: Epcast: Controlled Dissemination in Human-based Wireless Networks by means of Epidemic Spreading Models\nYear: 2007\n\nAbstract: Epidemics-inspired techniques have received huge attention in recent years from the distributed systems and networking communi- ties. These algorithms and protocols rely on probabilistic message repli- cation and redundancy to ensure reliable communication. Moreover, they have been successfully exploited to support group communication in dis- tributed systems, broadcasting, multicasting and information dissemina- tion in fixed and mobile networks. However, in most of the existing work, the probability of infection is determined heuristically, without relying on any analytical model. This often leads to unnecessarily high transmission overheads. In this paper we show that models of epidemic spreading in complex networks can be applied to the problem of tuning and controlling the dissemination of information in wireless ad hoc networks composed of devices carried by individuals, i.e., human-based networks. The novelty of our idea resides in the evaluation and exploitation of the structure of the underlying human network for the automatic tuning of the dissemination process in order to improve the protocol performance. We evaluate the results using synthetic mobility models and real human contacts traces.","Title: Implementing incremental code migration with XML\nYear: 2000\n\nAbstract: We demonstrate how XML and related technologies can be used for code mobility at any granularity, thus overcoming the restrictions of existing approaches. By not fixing a particular granularity for mobile code, we enable complete programs as well as individual lines of code to be sent across the network. We define the concept of incremental code mobility as the ability to migrate and add, remove, or replace code fragments (i.e., increments) in a remote program. The combination of fine-grained and incremental migration achieves a previously unavailable degree of flexibility. We examine the application of incremental and fine-grained code migration to a variety of domains, including user interface management, application management on mobile thin clients, for example PDAs, and management of distributed documents.","Title: Smartphone sensing offloading for efficiently supporting social sensing applications.\nYear: 2014\n\nAbstract: Mobile phones play a pivotal role in supporting ubiquitous and unobtrusive sensing of human activities. However, maintaining a highly accurate record of a user's behavior throughout the day imposes significant energy demands on the phone's battery. In this work, we investigate a new approach that can lead to significant energy savings for mobile applications that require continuous sensing of social activities. This is achieved by opportunistically offloading sensing to sensors embedded in the environment, leveraging sensing that may be available in typical modern buildings (e.g., room occupancy sensors, RFID access control systems). In this article, we present the design, implementation, and evaluation of METIS: an adaptive mobile sensing platform that efficiently supports social sensing applications. The platform implements a novel sensor task distribution scheme that dynamically decides whether to perform sensing on the phone or in the infrastructure, considering the energy consumption, accuracy, and mobility patterns of the user. By comparing the sensing distribution scheme with sensing performed solely on the phone or exclusively on the fixed remote sensors, we show, through benchmarks using real traces, that the opportunistic sensing distribution achieves over 60% and 40% energy savings, respectively. This is confirmed through a real world deployment in an office environment for over a month: we developed a social application over our frameworks, that is able to infer the collaborations and meetings of the users. In this setting the system preserves over 35% more battery life over pure phone sensing.","Title: XMILE: An XML Based Approach for Incremental Code Mobility and Update\nYear: 2002\n\nAbstract: The eXtensible Markup Language (XML) was originally defined to represent Web content, but it is increasingly used to define languages, such as XPL, that are used for coding executable algorithms, policies or scripts. XML-related standards, such as XPath and the Document Object Model, permit the flexible manipulation of fragments of XML code, which enables novel code migration and update paradigms. The XMILE approach that we describe in this paper exploits these mechanisms in order to achieve flexible and fine-grained code updates, even without stopping execution. We describe a Java-based prototype that implements XMILE and our experience in using XMILE in the domain of code updates on mobile devices.","Title: XMIDDLE: A Data-Sharing Middleware for Mobile Computing\nYear: 2002\n\nAbstract: An increasing number of distributed applications will be written for mobilehosts, such as laptop computers, third generation mobile phones, personaldigital assistants, watches and the like. Application engineers have to dealwith a new set of problems caused by mobility, such as low bandwidth, contextchanges or loss of connectivity. During disconnection, users will typicallyupdate local replicas of shared data independently from each other. Theresulting inconsistent replicas need to be reconciled upon re-connection. Tosupport building mobile applications that use both replication andreconciliation over ad-hoc networks, we have designed xmiddle, a mobilecomputing middleware. In this paper we describe xmiddle and show how it usesreflection capabilities to allow application engineers to influencereplication and reconciliation techniques. xmiddle enables the transparentsharing of XML documents across heterogeneous mobile hosts, allowing on-lineand off-line access to data. We describe xmiddle using a collaborativee-shopping case study on mobile clients.","Title: Towards A Mobile Computing Middleware: A Synergy of Reflection and Mobile Code Techniques\nYear: 2001\n\nAbstract: The increasing popularity of wireless devices, such asmobile phones, personal digital assistants, watches and thelike, is enabling new classes of applications that presentchallenging problems to designers. Applications have tobe aware of, and adapt to, frequent variations in the contextof execution, such as fluctuating network bandwidth,decreasing battery power, changes in location or device capabilities,and so on. In this paper, we argue that middlewaresolutions for wired distributed systems cannot be usedin a mobile setting, as the principle of transparency thathas driven their design runs counter to the new degrees ofawareness imposed by mobility. We propose a synergy ofreflection and code mobility as a means for middleware togive applications the desired level of flexibility to react tochanges happening in the environment, including those thathave not necessarily been foreseen by middleware designers.We use the sharing and processing of images as anapplication scenario to highlight the advantages of our approach.","Title: Mining users' significant driving routes with low-power sensors\nYear: 2014\n\nAbstract: While there is significant work on sensing and recognition of significant places for users, little attention has been given to users' significant routes. Recognizing these routine journeys, can open doors for the development of novel applications, like personalized travel alerts, and enhancement of user's travel experience. However, the high energy consumption of traditional location sensing technologies, such as GPS or WiFi based localization, is a barrier to passive and ubiquitous route sensing through smartphones. In this paper, we present a passive route sensing framework that continuously monitors a vehicle user solely through a phone's gyroscope and accelerometer. This approach can differentiate and recognize various routes taken by the user by time warping angular speeds experienced by the phone while in transit and is independent of phone orientation and location within the vehicle, small detours and traffic conditions. We compare the route learning and recognition capabilities of this approach with GPS trajectory analysis and show that it achieves similar performance. Moreover, with an embedded co-processor, common to most new generation phones, it achieves energy savings of an order of magnitude over the GPS sensor.","Title: Group Colocation Behavior In Technological Social Networks\nYear: 2014\n\nAbstract: We analyze two large datasets from technological networks with location and social data: user location records from an online location-based social networking service, and anonymized telecommunications data from a European cellphone operator, in order to investigate the differences between individual and group behavior with respect to physical location. We discover agreements between the two datasets: firstly, that individuals are more likely to meet with one friend at a place they have not visited before, but tend to meet at familiar locations when with a larger group. We also find that groups of individuals are more likely to meet at places that their other friends have visited, and that the type of a place strongly affects the propensity for groups to meet there. These differences between group and solo mobility has potential technological applications, for example, in venue recommendation in location-based social networks.","Title: The architecture of innovation: tracking face-to-face interactions with ubicomp technologies\nYear: 2014\n\nAbstract: The layouts of the buildings we live in shape our everyday lives. In office environments, building spaces affect employees' communication, which is crucial for productivity and innovation. However, accurate measurement of how spatial layouts affect interactions is a major challenge and traditional techniques may not give an objective view. We measure the impact of building spaces on social interactions using wearable sensing devices. We study a single organization that moved between two different buildings, affording a unique opportunity to examine how space alone can affect interactions. The analysis is based on two large scale deployments of wireless sensing technologies: short-range, lightweight RFID tags capable of detecting face-to-face interactions. We analyze the traces to study the impact of the building change on social behavior, which represents a first example of using ubiquitous sensing technology to study how the physical design of two workplaces combines with organizational structure to shape contact patterns.","Title: DSP.Ear: leveraging co-processor support for continuous audio sensing on smartphones\nYear: 2014\n\nAbstract: The rapidly growing adoption of sensor-enabled smartphones has greatly fueled the proliferation of applications that use phone sensors to monitor user behavior. A central sensor among these is the microphone which enables, for instance, the detection of valence in speech, or the identification of speakers. Deploying multiple of these applications on a mobile device to continuously monitor the audio environment allows for the acquisition of a diverse range of sound-related contextual inferences. However, the cumulative processing burden critically impacts the phone battery. To address this problem, we propose DSP.Ear -- an integrated sensing system that takes advantage of the latest low-power DSP co-processor technology in commodity mobile devices to enable the continuous and simultaneous operation of multiple established algorithms that perform complex audio inferences. The system extracts emotions from voice, estimates the number of people in a room, identifies the speakers, and detects commonly found ambient sounds, while critically incurring little overhead to the device battery. This is achieved through a series of pipeline optimizations that allow the computation to remain largely on the DSP. Through detailed evaluation of our prototype implementation we show that, by exploiting a smartphone's co-processor, DSP.Ear achieves a 3 to 7 times increase in the battery lifetime compared to a solution that uses only the phone's main processor. In addition, DSP.Ear is 2 to 3 times more power efficient than a naïve DSP solution without optimizations. We further analyze a large-scale dataset from 1320 Android users to show that in about 80-90% of the daily usage instances DSP.Ear is able to sustain a full day of operation (even in the presence of other smartphone workloads) with a single battery charge.","Title: OpenStreetCab: Exploiting Taxi Mobility Patterns in New York City to Reduce Commuter Costs.\nYear: 2015\n\nAbstract: The rise of Uber as the global alternative taxi operator has attracted a lot of interest recently. Aside from the media headlines which discuss the new phenomenon, e.g. on how it has disrupted the traditional transportation industry, policy makers, economists, citizens and scientists have engaged in a discussion that is centred around the means to integrate the new generation of the sharing economy services in urban ecosystems. In this work, we aim to shed new light on the discussion, by taking advantage of a publicly available longitudinal dataset that describes the mobility of yellow taxis in New York City. In addition to movement, this data contains information on the fares paid by the taxi customers for each trip. As a result we are given the opportunity to provide a first head to head comparison between the iconic yellow taxi and its modern competitor, Uber, in one of the world's largest metropolitan centres. We identify situations when Uber X, the cheapest version of the Uber taxi service, tends to be more expensive than yellow taxis for the same journey. We also demonstrate how Uber's economic model effectively takes advantage of well known patterns in human movement. Finally, we take our analysis a step further by proposing a new mobile application that compares taxi prices in the city to facilitate traveller's taxi choices, hoping to ultimately to lead to a reduction of commuter costs. Our study provides a case on how big datasets that become public can improve urban services for consumers by offering the opportunity for transparency in economic sectors that lack up to date regulations.","Title: CARISMA: context-aware reflective middleware system for mobile applications\nYear: 2003\n\nAbstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed applications that have to adapt to changes in context, such as variations in network bandwidth, battery power, connectivity, reachability of services and hosts, etc. In this paper, we describe CARISMA, a mobile computing middleware which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. The middleware provides software engineers with primitives to describe how context changes should be handled using policies. These policies may conflict. We classify the different types of conflicts that may arise in mobile computing and argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which policy conflicts can be handled; this method uses a microeconomic approach that relies on a particular type of sealed-bid auction. We describe how this method is implemented in the CARISMA middleware architecture and sketch a distributed context-aware application for mobile devices to illustrate how the method works in practice. We show, by way of a systematic performance evaluation, that conflict resolution does not imply undue overheads, before comparing our research to related work and concluding the paper.","Title: Introduction\nYear: 2019\n\nAbstract: The tremendous advances in wireless networks, mobile computing, and sensor networks, along with the rapid growth of small, portable and powerful computing devices, offers more and more opportunities for pervasive computing and communications. This topic deals with cutting-edge research in various aspects related to the theory and practice of mobile computing or wireless and mobile networking. These aspects include architectures, algorithms, networks, protocols, modeling and performance issues, data management, and novel applications and services. The aim of this topic is to bring together computer scientists and engineers from both academia and industry working in this exciting and emerging area of pervasive computing and communications, to share their ideas and results with their peers.","Title: Q-CAD: QoS and context aware discovery framework for mobile systems\nYear: 2005\n\nAbstract: This paper presents Q-CAD, a resource discovery frame- work that enables pervasive computing applications to dis- cover and select the resource(s) best satisfying the user needs, taking the current execution context and quality-of- service (QoS) requirements into account. The available re- sources are first screened, so that only those suitable to the current execution context of the application will be consid- ered; the shortlisted resources are then evaluated against the QoS needs of the application, and a binding is estab- lished to the best available.","Title: Adaptive distributed indexing for spatial queries in sensor networks\nYear: 2005\n\nAbstract: Sensor networks have opened new horizons and opportunities for a variety of environmental monitoring, surveillance and healthcare applications. One of the major tasks of sensor networks is the distributed collection and processing of sensor readings over extended periods of time. We propose an energy- efficient hierarchical indexing approach for spatial data in sensor networks. Our indexing technique allows roaming users to navigate through sensor networks distributed over large geographical areas and to pose spatial queries about the location of the data in the network. The major challenge in designing such indexes is the minimization of the total amount of traffic needed to create and maintain the indexes, which is a function of region activity and the actual query rates. Given the dynamic character of the setting, these parameters might in fact change during the network operation, calling for a very adaptive solution.","Title: Opportunistic Mobile Sensor Data Collection with SCAR\nYear: 2007\n\nAbstract: Sensors are now embedded in all sorts of devices (such as phones and PDAs) and attached to many moving things such as robots, vehicles and animals. The collection of data from these mobile sensors presents challenges related to the variability of the topology of the sensor network and the need to limit communication (for energy or bandwidth sav- ing). Fortunately, the data collected, despite considerable, is often delay tolerant and its delivery to the sinks is, in most cases, not time critical. We have devised SCAR, a context aware opportunistic routing protocol which allows efficient routing of sensor data to sinks, through selection of best paths by prediction over movement patterns and current battery level of nodes. In this paper we present the implementation of the protocol in Contiki and validate the approach through the use of the COOJA simulator with mobility traces provided by the Ze- braNet Project. We compare the performance with respect to random choice based dissemination.","Title: Seal-2-Seal: A delay-tolerant protocol for contact logging in wildlife monitoring sensor networks\nYear: 2008\n\nAbstract: Sensor networks are now enabling the monitoring of var- ious environmental phenomena with more accuracy than the previous labour intensive and less technological solutions. This paper is concerned with the application of opportunis- tic networking techniques to wildlife monitoring, where the sensors are attached to animals moving in their habitat. We present Seal-2-Seal, a novel protocol for logging of node (i.e., animal) contacts in mobile networks and for dissemi- nation of that information to sinks for further analysis. The protocol utilises an efficient data summary mechanism to reduce the amount of information that needs to be trans- mitted, thus reducing energy consumption. To evaluate the performance of the protocol, we implemented it for the Con- tiki operating system on sensor devices and ran simulations based on real-life mobility traces using the Cooja emulator.","Title: The Power of Mobile Computing in a Social Era\nYear: 2010\n\nAbstract: The most powerful trend in mobile computing is that of increased online social activity. To meet users' future expectations, mobile computing researchers must consider current limitations and identify upcoming challenges.","Title: Mining User Mobility Features for Next Place Prediction in Location-Based Services\nYear: 2012\n\nAbstract: Mobile location-based services are thriving, providing an unprecedented opportunity to collect fine grained spatio-temporal data about the places users visit. This multi-dimensional source of data offers new possibilities to tackle established research problems on human mobility, but it also opens avenues for the development of novel mobile applications and services. In this work we study the problem of predicting the next venue a mobile user will visit, by exploring the predictive power offered by different facets of user behavior. We first analyze about 35 million check-ins made by about 1 million Foursquare users in over 5 million venues across the globe, spanning a period of five months. We then propose a set of features that aim to capture the factors that may drive users' movements. Our features exploit information on transitions between types of places, mobility flows between venues, and spatio-temporal characteristics of user check-in patterns. We further extend our study combining all individual features in two supervised learning models, based on linear regression and M5 model trees, resulting in a higher overall prediction accuracy. We find that the supervised methodology based on the combination of multiple features offers the highest levels of prediction accuracy: M5 model trees are able to rank in the top fifty venues one in two user check-ins, amongst thousands of candidate items in the prediction list.","Title: Mining open datasets for transparency in taxi transport in metropolitan environments\nYear: 2015\n\nAbstract: Abstract Uber has recently been introducing novel practices in urban taxi transport. Journey prices can change dynamically in almost real time and also vary geographically from one area to another in a city, a strategy known as surge pricing. In this paper, we explore the power of the new generation of open datasets towards understanding the impact of the new disruption technologies that emerge in the area of public transport. With our primary goal being a more transparent economic landscape for urban commuters, we provide a direct price comparison between Uber and the Yellow Cab company in New York. We discover that Uber, despite its lower standard pricing rates, effectively charges higher fares on average, especially during short in length, but frequent in occurrence, taxi journeys. Building on this insight, we develop a smartphone application, OpenStreetCab, that offers a personalized consultation to mobile users on which taxi provider is cheaper for their journey. Almost five months after its launch, the app has attracted more than three thousand users in a single city. Their journey queries have provided additional insights on the potential savings similar technologies can have for urban commuters, with a highlight being that on average, a user in New York saves 6 U.S. Dollars per taxi journey if they pick the cheapest taxi provider. We run extensive experiments to show how Uber’s surge pricing is the driving factor of higher journey prices and therefore higher potential savings for our application’s users. Finally, motivated by the observation that Uber’s surge pricing is occurring more frequently that intuitively expected, we formulate a prediction task where the aim becomes to predict a geographic area’s tendency to surge. Using exogenous to Uber data, in particular Yellow Cab and Foursquare data, we show how it is possible to estimate customer demand within an area, and by extension surge pricing, with high accuracy.","Title: Smart Sensing Systems for the Daily Drive.\nYear: 2016\n\nAbstract: When driving, you might sometimes wonder, \"Are there any disruptions on my regular route that might delay me, and will I be able to find a parking space when I arrive?\" Two smartphone-based prototype systems can help answer these questions. The first is ParkSense, which can be used to sense on-street parking-space occupancy when coupled with electronic parking payment systems. The second system can sense and recognize a user's repeated car journeys, which can be used to provide personalized alerts to the user. Both systems aim to minimize the impact of sensing tasks on the device's lifetime so that the user can continue to use the device for its primary purpose. This department is part of a special issue on smart vehicle spaces.","Title: The International Postal Network And Other Global Flows As Proxies For National Wellbeing\nYear: 2016\n\nAbstract: The digital exhaust left by flows of physical and digital commodities provides a rich measure of the nature, strength and significance of relationships between countries in the global network. With this work, we examine how these traces and the network structure can reveal the socioeconomic profile of different countries. We take into account multiple international networks of physical and digital flows, including the previously unexplored international postal network. By measuring the position of each country in the Trade, Postal, Migration, International Flights, IP and Digital Communications networks, we are able to build proxies for a number of crucial socioeconomic indicators such as GDP per capita and the Human Development Index ranking along with twelve other indicators used as benchmarks of national well-being by the United Nations and other international organisations. In this context, we have also proposed and evaluated a global connectivity degree measure applying multiplex theory across the six networks that accounts for the strength of relationships between countries. We conclude by showing how countries with shared community membership over multiple networks have similar socioeconomic profiles. Combining multiple flow data sources can help understand the forces which drive economic activity on a global level. Such an ability to infer proxy indicators in a context of incomplete information is extremely timely in light of recent discussions on measurement of indicators relevant to the Sustainable Development Goals.","Title: Integrating security and usability into the requirements and design process\nYear: 2007\n\nAbstract: According to Ross Anderson, 'Many systems fail because their designers protect the wrong things or protect the right things in the wrong way'. Surveys also show that security incidents in industry are rising, which highlights the difficulty of designing good security. Some recent approaches have targeted security from the technological perspective, others from the human computer interaction angle, offering better User Interfaces (UIs) for improved usability of security mechanisms. However, usability issues also extend beyond the user interface and should be considered during system requirements and design. In this paper, we describe Appropriate and Effective Guidance for Information Security (AEGIS), a methodology for the development of secure and usable systems. AEGIS defines a development process and a UML meta-model of the definition and the reasoning over the system's assets. AEGIS has been applied to case studies in the area of Grid computing and we report on one of these.","Title: Beyond location check-ins: Exploring physical and soft sensing to augment social check-in apps\nYear: 2015\n\nAbstract: Smartphone sensing research has been advancing at a brisk pace. Yet, current social networking services often only take advantage of location sensing: applications like Foursquare use the phone's GPS and Wi-Fi radios to infer the user's location to simplify checking-in to a place. However, smartphone sensing could be exploited to considerably expand the spectrum of information a user can share with a few clicks with friends: not only the location of an event but activities such as “cooking dinner” or “waiting for a bus” can be predicted and suggested to the user to ease the check-in process. In this paper we show how mobile phone sensing can be used in this sense. For this prediction process to be accurate however, sensors need to be sampled often, with a considerable impact on the phone battery. To alleviate this issue, we explore streams of phone usage data (soft sensors), such as application usage, messages, and phone calls for predicting the user's activity in a more efficient fashion for augmenting mobile social check-in apps. We have deployed our application and collected a dataset of over 2700 check-ins to 48 activities from 20 users. Our analysis shows a prediction accuracy of 75% when offering 5 check-in suggestions to users. Furthermore, we show that when using only soft sensors we can achieve very similar performance to that obtained with real sensors, thereby significantly reducing the impact on the phone battery. This finding might have a potentially high impact on smartphone based activity check-in apps.","Title: Studying human behavior at the intersection of mobile sensing and complex networks (Keynote abstract)\nYear: 2016\n\nAbstract: Summary form only given. With the advent of powerful and inexpensive sensing technology the ability to study human behaviour and activity at large scale and for long periods is becoming a firm reality. Wearables and mobile devices further allow the continuous physical colocation with the users. This reality generates new challenges but also opens the door to potentially innovative ways of understanding our daily lives. In this talk we will discuss our experience in large mobile sensor deployments and in using complex network science for the analysis of mobile sensing data. We will discuss the issues raised by mobile sensing big data in terms of data crowdsourcing, continuous sensing challenges, data analysis, privacy, user feedback. Examples will be drawn from our healthcare, transport, urban planning and organization analytics studies.","Title: Topological Properties and Temporal Dynamics of Place Networks in Urban Environments.\nYear: 2015\n\nAbstract: Understanding the spatial networks formed by the trajectories of mobile users can be beneficial to applications ranging from epidemiology to local search. Despite the potential for impact in a number of fields, several aspects of human mobility networks remain largely unexplored due to the lack of large-scale data at a fine spatiotemporal resolution. Using a longitudinal dataset from the location-based service Foursquare, we perform an empirical analysis of the topological properties of place networks and note their resemblance to online social networks in terms of heavy-tailed degree distributions, triadic closure mechanisms and the small world property. Unlike social networks however, place networks present a mixture of connectivity trends in terms of assortativity that are surprisingly similar to those of the web graph. We take advantage of additional semantic information to interpret how nodes that take on functional roles such as `travel hub', or `food spot' behave in these networks. Finally, motivated by the large volume of new links appearing in place networks over time, we formulate the classic link prediction problem in this new domain. We propose a novel variant of gravity models that brings together three essential elements of inter-place connectivity in urban environments: network-level interactions, human mobility dynamics, and geographic distance. We evaluate this model and find it outperforms a number of baseline predictors and supervised learning algorithms on a task of predicting new links in a sample of one hundred popular cities.","Title: Measuring Urban Social Diversity Using Interconnected Geo-Social Networks.\nYear: 2016\n\nAbstract: Large metropolitan cities bring together diverse individuals, creating opportunities for cultural and intellectual exchanges, which can ultimately lead to social and economic enrichment. In this work, we present a novel network perspective on the interconnected nature of people and places, allowing us to capture the social diversity of urban locations through the social network and mobility patterns of their visitors. We use a dataset of approximately 37K users and 42K venues in London to build a network of Foursquare places and the parallel Twitter social network of visitors through check-ins. We define four metrics of the social diversity of places which relate to their social brokerage role, their entropy, the homogeneity of their visitors and the amount of serendipitous encounters they are able to induce. This allows us to distinguish between places that bring together strangers versus those which tend to bring together friends, as well as places that attract diverse individuals as opposed to those which attract regulars. We correlate these properties with wellbeing indicators for London neighbourhoods and discover signals of gentrification in deprived areas with high entropy and brokerage, where an influx of more affluent and diverse visitors points to an overall improvement of their rank according to the UK Index of Multiple Deprivation for the area over the five-year census period. Our analysis sheds light on the relationship between the prosperity of people and places, distinguishing between different categories and urban geographies of consequence to the development of urban policy and the next generation of socially-aware location-based applications.","Title: Smart phone based systems for social psychological research: challenges and design guidelines\nYear: 2011\n\nAbstract: Social psychology research deals with understanding many aspects of human behavior, and this helps not only to gain insights into this complex phenomenon but also to provide useful feedback to the participants. Social psychological research is mainly conducted through self-reports and surveys, however, this methodology is laborious and requires considerable offline analysis. Moreover, self-reports are also found to be biased towards pleasant experiences. Mobile phones represent a perfect platform for conducting social psychological research as they are ubiquitous, unobtrusive, and sensor-rich devices. However, limited battery and computing power, and expensive data plans make it difficult to support various demanding sensing and computation requirements of the social psychological research. In this paper, we describe the specific challenges in building systems based on off-the-shelf mobile phones for conducting social experiments, and provide design guidelines based on our recent works for implementing such systems.","Title: Monitoring A Large Construction Site Using Wireless Sensor Networks\nYear: 2015\n\nAbstract: Despite the significant advances made by wireless sensor network research, deployments of such networks in real application environments are fraught with significant difficulties and challenges that include robust topology design, network diagnostics and maintenance. Based on our experience of a six-month-long wireless sensor network deployment in a large construction site, we highlight these challenges and argue the need for new tools and enhancements to current protocols to address these challenges.","Title: ZOE: A Cloud-less Dialog-enabled Continuous Sensing Wearable Exploiting Heterogeneous Computation\nYear: 2015\n\nAbstract: The wearable revolution, as a mass-market phenomenon, has finally arrived. As a result, the question of how wearables should evolve over the next 5 to 10 years is assuming an increasing level of societal and commercial importance. A range of open design and system questions are emerging, for instance: How can wearables shift from being largely health and fitness focused to tracking a wider range of life events? What will become the dominant methods through which users interact with wearables and consume the data collected? Are wearables destined to be cloud and/or smartphone dependent for their operation? Towards building the critical mass of understanding and experience necessary to tackle such questions, we have designed and implemented ZOE - a match-box sized (49g) collar- or lapel-worn sensor that pushes the boundary of wearables in an important set of new directions. First, ZOE aims to perform multiple deep sensor inferences that span key aspects of everyday life (viz. personal, social and place information) on continuously sensed data; while also offering this data not only within conventional analytics but also through a speech dialog system that is able to answer impromptu casual questions from users. (Am I more stressed this week than normal?) Crucially, and unlike other rich-sensing or dialog supporting wearables, ZOE achieves this without cloud or smartphone support - this has important side-effects for privacy since all user information can remain on the device. Second, ZOE incorporates the latest innovations in system-on-a-chip technology together with a custom daughter-board to realize a three-tier low-power processor hierarchy. We pair this hardware design with software techniques that manage system latency while still allowing ZOE to remain energy efficient (with a typical lifespan of 30 hours), despite its high sensing workload, small form-factor, and need to remain responsive to user dialog requests.","Title: Developing and Deploying Mobile Sensing Applications in the Wild\nYear: 2016\n\nAbstract: Summary form only given. With the advent of powerful and inexpensive sensing technology the ability to study human behaviour and activity at large scale and for long periods is becoming a firm reality. Wearables and mobile devices further allow the continuous physical colocation with the users. This reality generates new challenges but also opens the door to potentially innovative ways of understanding our daily lives. In this talk we will discuss our experience in large mobile sensor deployments. We will discuss the issues raised by mobile sensing big data in terms of data crowdsourcing, continuous sensing challenges, data analysis, privacy, user feedback. Examples will be drawn from our healthcare, transport, urban planning and organization analytics studies.","Title: Towards multimodal deep learning for activity recognition on mobile devices.\nYear: 2016\n\nAbstract: Current smartphones and smartwatches come equipped with a variety of sensors, from light sensor and inertial sensors to radio interfaces, enabling applications running on these devices to make sense of their surrounding environment. Rather than using sensors independently, combining their sensing capabilities facilitates more interesting and complex applications to emerge (e.g., user activity recognition). But differences between sensors ranging from sampling rate to data generation model (event triggered or continuous sampling) make integration of sensor streams challenging. Here we investigate the opportunity to use deep learning to perform this integration of sensor data from multiple sensors. The intuition is that neural networks can identify nonintuitive features largely from cross-sensor correlations which can result in a more accurate estimation. Initial results with a variant of a Restricted Boltzmann Machine (RBM), show better performance with this new approach compared to classic solutions.","Title: LEO: scheduling sensor inference algorithms across heterogeneous mobile processors and network resources.\nYear: 2016\n\nAbstract: Mobile apps that use sensors to monitor user behavior often employ resource heavy inference algorithms that make computational offloading a common practice. However, existing schedulers/offloaders typically emphasize one primary offloading aspect without fully exploring complementary goals (e.g., heterogeneous resource management with only partial visibility into underlying algorithms, or concurrent sensor app execution on a single resource) and as a result, may overlook performance benefits pertinent to sensor processing. We bring together key ideas scattered in existing offloading solutions to build LEO -- a scheduler designed to maximize the performance for the unique workload of continuous and intermittent mobile sensor apps without changing their inference accuracy. LEO makes use of domain specific signal processing knowledge to smartly distribute the sensor processing tasks across the broader range of heterogeneous computational resources of high-end phones (CPU, co-processor, GPU and the cloud). To exploit short-lived, but substantial optimization opportunities, and remain responsive to the needs of near real-time apps such as voice-based natural user interfaces, LEO runs as a service on a low-power co-processor unit (LPU) to perform both frequent and joint schedule optimization for concurrent pipelines. Depending on the workload and network conditions, LEO is between 1.6 and 3 times more energy efficient than conventional cloud offloading with CPU-bound sensor sampling. In addition, even if a general-purpose scheduler is optimized directly to leverage an LPU, we find LEO still uses only a fraction (< 1/7) of the energy overhead for scheduling and is up to 19% more energy efficient for medium to heavy workloads.","Title: Bridge structural monitoring through a vibration energy harvesting wireless sensor network: Poster Abstract.\nYear: 2016\n\nAbstract: Structural monitoring applications such as corrosion assessment, measurement of concrete temperature or moisture content of critical bridge structures can greatly benefit from the use of wireless sensor networks (WSNs), however energy harvesting for the operation of the network remains a challenge in this setting. We present a multihop vibration-based energy harvesting WSN system for bridge monitoring applications. Our preliminary simulation experiments show that the system is able to maintain energy neutral operation over time, preserving energy with careful management of sleep and communication times.","Title: Developing and Deploying a Taxi Price Comparison Mobile App in the Wild: Insights and Challenges.\nYear: 2018\n\nAbstract: As modern transportation systems become more complex, there is need for mobile applications that allow travelers to navigate efficiently in cities. In taxi transport the recent proliferation of Uber has introduced new norms including a flexible pricing scheme where journey costs can change rapidly depending on passenger demand and driver supply. To make informed choices on the most appropriate provider for their journeys, travelers need access to knowledge about provider pricing in real time. To this end, we developed OpenStreetCab a mobile application that offers advice on taxi transport comparing provider prices. We describe its development and deployment in two cities, London and New York, and analyse thousands of user journey queries to compare the price patterns of Uber against major local taxi providers. We have observed large heterogeneity across the taxi transport markets in the two cities. This motivated us to perform a price validation and measurement experiment on the ground comparing Uber and Black Cabs in London. The experimental results reveal interesting insights: not only they confirm feedback on pricing and service quality received by professional driver users, but also they reveal the tradeoffs between prices and journey times between taxi providers. With respect to journey times in particular, we show how experienced taxi drivers, in the majority of the cases, are able to navigate faster to a destination compared to drivers who rely on modern navigation systems. We provide evidence that this advantage becomes stronger in the centre of a city where urban density is high.","Title: Detecting Socio-Economic Impact of Cultural Investment Through Geo-Social Network Analysis.\nYear: 2018\n\nAbstract: © Copyright 2017, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Taking advantage of nearly 4 million transition records for three years in London from a popular location-based social network service, Foursquare, we study how to track the impact and measure the effectiveness of cultural investment in small urban areas. We reveal the underlying relationships between socio-economic status, local cultural expenditure, and network features extracted from user mobility trajectories. This research presents how geo-social and mobile services more generally can be used as a proxy to track local changes as government financial effort is put in developing urban areas, and thus gives evidence and suggestions for further policy-making and investment optimization.","Title: Mobile Sensing at the Service of Mental Well-being: a Large-scale Longitudinal Study.\nYear: 2017\n\nAbstract: Measuring mental well-being with mobile sensing has been an increasingly active research topic. Pervasiveness of smartphones combined with the convenience of mobile app distribution platforms (e.g., Google Play) provide a tremendous opportunity to reach out to millions of users. However, the studies at the confluence of mental health and mobile sensing have been longitudinally limited, controlled, or confined to a small number of participants. In this paper we report on what we believe is the largest longitudinal in-the-wild study of mood through smartphones. We describe an Android app to collect participants' self-reported moods and system triggered experience sampling data while passively measuring their physical activity, sociability, and mobility via their device's sensors. We report the results of a large-scale analysis of the data collected for about three years from 18,000 users. The paper makes three primary contributions. First, we show how we used physical and software sensors in smartphones to automatically and accurately identify routines. Then, we demonstrate the strong correlation between these routines and users' personality, well-being perception, and other psychological variables. Finally, we explore predictability of users' mood using their passive sensing data. Our findings show that, especially for weekends, mobile sensing can be used to predict users' mood with an accuracy of about 70%. These results have the potential to impact the design of future mobile apps for mood/behavior tracking and interventions.","Title: Accelerating Mobile Audio Sensing Algorithms through On-Chip GPU Offloading.\nYear: 2017\n\nAbstract: GPUs have recently enjoyed increased popularity as general purpose software accelerators in multiple application domains including computer vision and natural language processing. However, there has been little exploration into the performance and energy trade-offs mobile GPUs can deliver for the increasingly popular workload of deep-inference audio sensing tasks, such as, spoken keyword spotting in energy-constrained smartphones and wearables. In this paper, we study these trade-offs and introduce an optimization engine that leverages a series of structural and memory access optimization techniques that allow audio algorithm performance to be automatically tuned as a function of GPU device specifications and model semantics. We find that parameter optimized audio routines obtain inferences an order of magnitude faster than sequential CPU implementations, and up to 6.5x times faster than cloud offloading with good connectivity, while critically consuming 3-4x less energy than the CPU. Under our optimized GPU, conventional wisdom about how to use the cloud and low power chips is broken. Unless the network has a throughput of at least 20Mbps (and a RTT of 25 ms or less), with only about 10 to 20 seconds of buffering audio data for batched execution, the optimized GPU audio sensing apps begin to consume less energy than cloud offloading. Under such conditions we find the optimized GPU can provide energy benefits comparable to low-power reference DSP implementations with some preliminary level of optimization; in addition to the GPU always winning with lower latency.","Title: Using human raters to characterize the psychological characteristics of GPS-based places.\nYear: 2017\n\nAbstract: This paper showcases an approach to combining smart-phone sensing technology, web mapping services, and psychological assessments to enhance our understanding of the psychological characteristics of places. For two weeks, twenty-six students used a smartphone app that passively collected GPS sensor data. Human raters then characterized their most frequently visited places on a number of psychological characteristics, such as ambience (e.g. how safe, urban, lively a place was perceived) and personality (e.g. a place's perceived extroversion and conscientiousness). We explored the relationship between these place characteristics and participants own personality traits, showing how the personality traits of the average visitor to a location can be similar or different from the place's characteristics. We conclude with a discussion of how this approach can be used in future research on places.","Title: Understanding the Role of Places and Activities on Mobile Phone Interaction and Usage Patterns.\nYear: 2017\n\nAbstract: User interaction patterns with mobile apps and notifications are generally complex due to the many factors involved. However a deep understanding of what influences them can lead to more acceptable applications that are able to deliver information at the right time. In this paper, we present for the first time an in-depth analysis of interaction behavior with notifications in relation to the location and activity of users. We conducted an in-situ study for a period of two weeks to collect more than 36,000 notifications, 17,000 instances of application usage, 77,000 location samples, and 487 days of daily activity entries from 26 students at a UK university.\n\nOur results show that users’ attention towards new notifications and willingness to accept them are strongly linked to the location they are in and in minor part to their current activity. We consider both users’ receptivity and attentiveness, and we show that different response behaviors are associated to different locations. These findings are fundamental from a design perspective since they allow us to understand how certain types of places are linked to specific types of interaction behavior. This information can be used as a basis for the development of novel intelligent mobile applications and services.","Title: Detecting Emerging Activity-Based Working Traits through Wearable Technology.\nYear: 2017\n\nAbstract: A recent trend in corporate real-estate is Activity-Based Working (ABW). The ABW concept removes designated desks but offers different work settings designed to support typical work activities. In this context there is still a need for objective data to understand the implications of these design decisions. We aim to contribute by using automated data collection to study how ABW’s principles impact office usage and dynamics.\n\nTo this aim we analyse team dynamics and employees’ tie strength in relation to space usage and organisational hierarchy using data collected with wearable devices in a company adopting ABW principles. Our findings show that the office fosters interactions across team boundaries and among the lower levels of the hierarchy suggesting a strong lateral communication. Employees also tend to have low space exploration on a daily basis which is instead more prevalent during an average week and strong social clusters seem to be resisting the ABW principles of space dynamics. With the availability of two additional data sets about social encounters in traditional offices we highlight traits emerging from the application of ABW’s principles. In particular, we observe how the absence of designated desks might be responsible for more rapid dynamics inside the office.\n\nIn more general terms, this work opens the door to new and scalable technology-based methodologies to study dynamic office usage and social interactions.","Title: Multimodal Deep Learning for Activity and Context Recognition.\nYear: 2017\n\nAbstract: Wearables and mobile devices see the world through the lens of half a dozen low-power sensors, such as, barometers, accelerometers, microphones and proximity detectors. But differences between sensors ranging from sampling rates, discrete and continuous data or even the data type itself make principled approaches to integrating these streams challenging. How, for example, is barometric pressure best combined with an audio sample to infer if a user is in a car, plane or bike? Critically for applications, how successfully sensor devices are able to maximize the information contained across these multi-modal sensor streams often dictates the fidelity at which they can track user behaviors and context changes. This paper studies the benefits of adopting deep learning algorithms for interpreting user activity and context as captured by multi-sensor systems. Specifically, we focus on four variations of deep neural networks that are based either on fully-connected Deep Neural Networks (DNNs) or Convolutional Neural Networks (CNNs). Two of these architectures follow conventional deep models by performing feature representation learning from a concatenation of sensor types. This classic approach is contrasted with a promising deep model variant characterized by modality-specific partitions of the architecture to maximize intra-modality learning. Our exploration represents the first time these architectures have been evaluated for multimodal deep learning under wearable data -- and for convolutional layers within this architecture, it represents a novel architecture entirely. Experiments show these generic multimodal neural network models compete well with a rich variety of conventional hand-designed shallow methods (including feature extraction and classifier construction) and task-specific modeling pipelines, across a wide-range of sensor types and inference tasks (four different datasets). Although the training and inference overhead of these multimodal deep approaches is in some cases appreciable, we also demonstrate the feasibility of on-device mobile and wearable execution is not a barrier to adoption. This study is carefully constructed to focus on multimodal aspects of wearable data modeling for deep learning by providing a wide range of empirical observations, which we expect to have considerable value in the community. We summarize our observations into a series of practitioner rules-of-thumb and lessons learned that can guide the usage of multimodal deep learning for activity and context detection.","Title: You Are Sensing, but Are You Biased?: A User Unaided Sensor Calibration Approach for Mobile Sensing\nYear: 2018\n\nAbstract: Mobile devices are becoming pervasive to our daily lives: they follow us everywhere and we use them for much more than just communication. These devices are also equipped with a myriad of different sensors that have the potential to allow the tracking of human activities, user patterns, location, direction and much more. Following this direction, many movements including sports, quantified self, and mobile health ones are starting to heavily rely on this technology, making it pivotal that the sensors offer high accuracy.\n\nHowever, heterogeneity in hardware manufacturing, slight substrate differences, electronic interference as well as external disturbances are just few of the reasons that limit sensor output accuracy which in turn hinders sensor usage in applications which need very high granularity and precision, such as quantified-self applications. Although, calibration of sensors is a widely studied topic in literature to the best of our knowledge no publicly available research exists that specifically tackles the calibration of mobile phones and existing methods that can be adapted for use in mobile devices not only require user interaction but they are also not adaptive to changes. Additionally, alternative approaches for performing more granular and accurate sensing exploit body-wide sensor networks using mobile phones and additional sensors; as one can imagine these techniques can be bulky, tedious, and not particularly user friendly. Moreover, existing techniques for performing data corrections post-acquisition can produce inconsistent results as they miss important context information provided from the device itself; which when used, has been shown to produce better results without a imposing a significant power-penalty.\n\nIn this paper we introduce a novel multiposition calibration scheme that is specifically targeted at mobile devices Our scheme exploits machine learning techniques to perform an adaptive, power-efficient auto-calibration procedure with which achieves high output sensor accuracy when compared to state of the art techniques without requiring any user interaction or special equipment beyond device itself Moreover, the energy costs associated with our approach are lower than the alternatives (such as Kalman filter based solutions) and the overall power penalty is < 5% when compared against power usage that is exhibited when using uncalibrated traces, thus, enabling our technique to be used efficiently on a wide variety of devices Finally, our evaluation illustrates that calibrated signals offer a tangible benefit in classification accuracy, ranging from 3 to 10%, over uncalibrated ones when using state of the art classifiers, on the other hand when using simpler SVM classifiers the classification improvement is boosted ranging from 8% to 12% making lower performing classifiers much more reliable Additionally, we show that for similar activities which are hard to distinguish otherwise, we reach an accuracy of > 95% when using neural network classifiers and > 88% when using SVM classifiers where uncalibrated data classification only reaches ~ 85% and ~ 80% respectively This can be a make or break factor in the use of accelerometer and gyroscope data in applications requiring high accuracy e g sports, health, games and others","Title: Surveying Areas in Developing Regions Through Context Aware Drone Mobility.\nYear: 2018\n\nAbstract: Developing regions are often characterized by large areas that are poorly reachable or explored. The mapping of these regions and the census of roaming populations in these areas are often difficult and sporadic.\n\nIn this paper we put forward an approach to aid area surveying which relies on autonomous drone mobility. In particular we illustrate the two main components of the approach. An efficient on-device object detection component, built on Convolutional Neural Networks, capable of detecting human settlements and animals on the ground with acceptable performance (latency and accuracy) and a path planning component, informed by the object identification module, which exploits Artificial Potential Fields to dynamically adapt the flight in order to gather useful information of the environment, while keeping optimal flight paths. We report some initial performance results of the on board visual perception module and describe our experimental platform based on a fixed-wing aircraft.","Title: Quantifying Privacy Loss of Human Mobility Graph Topology.\nYear: 2018\n\nAbstract: network, or graph, with nodes representing places of significance which an individual visits, such as their home, work, places of social amenity, etc., and edge weights corresponding to probability estimates of movements between these places. Previous research has shown that individuals can be identified by a small number of geolocated nodes in their mobility network, rendering mobility trace anonymization a hard task. In this paper we build on prior work and demonstrate that even when all location and timestamp information is removed from nodes, the graph topology of an individual mobility network itself is often uniquely identifying. Further, we observe that a mobility network is often unique, even when only a small number of the most popular nodes and edges are considered. We evaluate our approach using a large dataset of cell-tower location traces from 1 500 smartphone handsets with a mean duration of 430 days. We process the data to derive the top−N places visited by the device in the trace, and find that 93% of traces have a unique top−10 mobility network, and all traces are unique when considering top−15 mobility networks. Since mobility patterns, and therefore mobility networks for an individual, vary over time, we use graph kernel distance functions, to determine whether two mobility networks, taken at different points in time, represent the same individual. We then show that our distance metrics, while imperfect predictors, perform significantly better than a random strategy and therefore our approach represents a significant loss in privacy.","Title: Learning from Our Mistakes: Identifying Opportunities for Technology Intervention against Everyday Cognitive Failure.\nYear: 2018\n\nAbstract: There is growing opportunity for technologies to augment human memory and other cognitive processes, but systems to date typically either address known cognitive impairments such as autism and Alzheimers disease or look to enhance ones general capacity for a specific task. In contrast to these approaches, we argue that recognition and quantification of human error is key to the design of future co...","Title: Discovering Latent Patterns of Urban Cultural Interactions in WeChat for Modern City Planning.\nYear: 2018\n\nAbstract: Cultural activity is an inherent aspect of urban life and the success of a modern city is largely determined by its capacity to offer generous cultural entertainment to its citizens. To this end, the optimal allocation of cultural establishments and related resources across urban regions becomes of vital importance, as it can reduce financial costs in terms of planning and improve quality of life in the city, more generally. In this paper, we make use of a large longitudinal dataset of user location check-ins from the online social network WeChat to develop a data-driven framework for cultural planning in the city of Beijing. We exploit rich spatio-temporal representations on user activity at cultural venues and use a novel extended version of the traditional latent Dirichlet allocation model that incorporates temporal information to identify latent patterns of urban cultural interactions. Using the characteristic typologies of mobile user cultural activities emitted by the model, we determine the levels of demand for different types of cultural resources across urban areas. We then compare those with the corresponding levels of supply as driven by the presence and spatial reach of cultural venues in local areas to obtain high resolution maps that indicate urban regions with lack of cultural resources, and thus give suggestions for further urban cultural planning and investment optimisation.","Title: Predicting the Spatio-Temporal Evolution of Chronic Diseases in Population with Human Mobility Data.\nYear: 2018\n\nAbstract: © 2018 International Joint Conferences on Artificial Intelligence. All right reserved. Chronic diseases like cancer and diabetes are major threats to human life. Understanding the distribution and progression of chronic diseases of a population is important in assisting the allocation of medical resources as well as the design of policies in preemptive healthcare. Traditional methods to obtain large scale indicators on population health, e.g., surveys and statistical analysis, can be costly and time-consuming and often lead to a coarse spatio-temporal picture. In this paper, we leverage a dataset describing the human mobility patterns of citizens in a large metropolitan area. By viewing local human lifestyles we predict the evolution rate of several chronic diseases at the level of a city neighborhood. We apply the combination of a collaborative topic modeling (CTM) and a Gaussian mixture method (GMM) to tackle the data sparsity challenge and achieve robust predictions on health conditions simultaneously. Our method enables the analysis and prediction of disease rate evolution at fine spatio-temporal scales and demonstrates the potential of incorporating datasets from mobile web sources to improve population health monitoring. Evaluations using real-world check-in and chronic disease morbidity datasets in the city of London show that the proposed CTM+GMM model outperforms various baseline methods.","Title: Evaluating the impact of the 2012 Olympic Games policy on the regeneration of East London using spatio-temporal big data.\nYear: 2018\n\nAbstract: For urban governments, introducing policies has long been adopted as a main approach to instigate regeneration processes, and to promote social mixing and vitality within the city. However, due to the absence of large fine-grained datasets, the effects of these policies have been historically hard to evaluate. In this research, we illustrate how a combination of large-scale datasets, the Index of Deprivation and Foursquare data (an online geo-social network service) could be used to investigate the impact of the 2012 Olympic Games on the regeneration of East London neighbourhoods. We study and quantify both the physical and socio-economic aspects of this, where our empirical findings suggest that the target areas did indeed undergo regeneration after the Olympic project in some ways. In general, the growth rate of Foursquare venue density in Olympic host boroughs is higher than the cityu0027s average level since the preparation period of the Games and up to two years after the event. Furthermore, the deprivation levels in East London boroughs also saw improvements in various aspects after the Olympic Games. One negative outcome we notice is that the housing affordability becomes even more of an issue in East London areas with the regeneration gradually unfolding.","Title: Cultural Investment and Urban Socio-Economic Development: A Geo-Social Network Approach.\nYear: 2018\n\nAbstract: Being able to assess the impact of government-led investment onto socio-economic indicators in cities has long been an important target of urban planning. However, owing to the lack of large-scale data with a fine spatio-temporal resolution, there have been limitations in terms of how planners can track the impact and measure the effectiveness of cultural investment in small urban areas. Taking advantage of nearly 4 million transition records for 3 years in London from a popular location-based social network service, Foursquare, we study how the socio-economic impact of government cultural expenditure can be detected and predicted. Our analysis shows that network indicators such as average clustering coefficient or centrality can be exploited to estimate the likelihood of local growth in response to cultural investment. We subsequently integrate these features in supervised learning models to infer socio-economic deprivation changes for London's neighbourhoods. This research presents how geosocial and mobile services can be used as a proxy to track and predict socio-economic deprivation changes as government financial effort is put in developing urban areas and thus gives evidence and suggestions for further policymaking and investment optimization.","Title: The Specter of Malicious Computing: Securing the Internet of Things.\nYear: 2018\n\nAbstract: The Internet of Things (IoT) is taking off, and with it the vision of pervasive computing. Internet-enabled computers are now embedded in everything from cars to pacemakers to electronic door locks to home heating controllers. Unfortunately, security, safety, and privacy considerations have lagged behind in the race to build new applications and services. Researchers demonstrated years ago how to ...","Title: What Will You Do for the Rest of the Day?: An Approach to Continuous Trajectory Prediction.\nYear: 2018\n\nAbstract: Understanding and predicting human mobility is vital to a large number of applications, ranging from recommendations to safety and urban service planning. In some travel applications, the ability to accurately predict the user's future trajectory is vital for delivering high quality of service. The accurate prediction of detailed trajectories would empower location-based service providers with the ability to deliver more precise recommendations to users. Existing work on human mobility prediction has mainly focused on the prediction of the next location (or the set of locations) visited by the user, rather than on the prediction of the continuous trajectory (sequences of further locations and the corresponding arrival and departure times). Furthermore, existing approaches often return predicted locations as regions with coarse granularity rather than geographical coordinates, which limits the practicality of the prediction.\n\nIn this paper, we introduce a novel trajectory prediction problem: given historical data and a user's initial trajectory in the morning, can we predict the user's full trajectory later in the day (e.g. the afternoon trajectory)? The predicted continuous trajectory includes the sequence of future locations, the stay times, and the departure times. We first conduct a comprehensive analysis about the relationship between morning trajectories and the corresponding afternoon trajectories, and found there is a positive correlation between them. Our proposed method combines similarity metrics over the extracted temporal sequences of locations to estimate similar informative segments across user trajectories.\n\nOur evaluation shows results on both labeled and geographical trajectories with a prediction error reduced by 10-35% in comparison to the baselines. This improvement has the potential to enable precise location services, raising usefulness to users to unprecedented levels. We also present empirical evaluations with Markov model and Long Short Term Memory (LSTM), a state-of-the-art Recurrent Neural Network model. Our proposed method is shown to be more effective when smaller number of samples are used and is exponentially more efficient than LSTM.","Title: Keep Your Friends Close and Your Facebook Friends Closer: A Multiplex Network Approach to the Analysis of Offline and Online Social Ties.\nYear: 2014\n\nAbstract: Social media allow for an unprecedented amount of interaction between people online. A fundamental aspect of human social behavior, however, is the tendency of people to associate themselves with like-minded individuals, forming homogeneous social circles both online and offline. In this work, we apply a new model that allows us to distinguish between social ties of varying strength, and to observe evidence of homophily with regards to politics, music, health, residential sector & year in college, within the online and offline social network of 74 college students. We present a multiplex network approach to social tie strength, here applied to mobile communication data - calls, text messages, and co-location, allowing us to dimensionally identify relationships by considering the number of communication channels utilized between students. We find that strong social ties are characterized by maximal use of communication channels, while weak ties by minimal use. We are able to identify 75% of close friendships, 90% of weaker ties, and 90% of Facebook friendships as compared to reported ground truth. We then show that stronger ties exhibit greater profile similarity than weaker ones. Apart from high homogeneity in social circles with respect to political and health aspects, we observe strong homophily driven by music, residential sector and year in college. Despite Facebook friendship being highly dependent on residence and year, exposure to less homogeneous content can be found in the online rather than the offline social circles of students, most notably in political and music aspects.","Title: Predicting the temporal activity patterns of new venues.\nYear: 2018\n\nAbstract: Estimating revenue and business demand of a newly opened venue is paramount as these early stages often involve critical decisions such as first rounds of staffing and resource allocation. Traditionally, this estimation has been performed through coarse-grained measures such as observing numbers in local venues or venues at similar places (e.g., coffee shops around another station in the same city). The advent of crowdsourced data from devices and services carried by individuals on a daily basis has opened up the possibility of performing better predictions of temporal visitation patterns for locations and venues. In this paper, using mobility data from Foursquare, a location-centric platform, we treat venue categories as proxies for urban activities and analyze how they become popular over time. The main contribution of this work is a prediction framework able to use characteristic temporal signatures of places together with k-nearest neighbor metrics capturing similarities among urban regions, to forecast weekly popularity dynamics of a new venue establishment in a city neighborhood. We further show how we are able to forecast the popularity of the new venue after one month following its opening by using locality and temporal similarity as features. For the evaluation of our approach we focus on London. We show that temporally similar areas of the city can be successfully used as inputs of predictions of the visit patterns of new venues, with an improvement of 41% compared to a random selection of wards as a training set for the prediction task. We apply these concepts of temporally similar areas and locality to the real-time predictions related to new venues and show that these features can effectively be used to predict the future trends of a venue. Our findings have the potential to impact the design of location-based technologies and decisions made by new business owners.","Title: Understanding the Effects of the Neighbourhood Built Environment on Public Health with Open Data\nYear: 2019\n\nAbstract: The investigation of the effect of the built environment in a neighbourhood and how it impacts residents' health is of value to researchers from public health policy to social science. The traditional methods to assess this impact is through surveys which lead to temporally and spatially coarse grained data and are often not cost effective. Here we propose an approach to link the effects of neighbourhood services over citizen health using a technique that attempts to highlight the cause-effect aspects of these relationships. The method is based on the theory of propensity score matching with multiple 'doses' and it leverages existing fine grained open web data. To demonstrate the method, we study the effect of sport venue presence on the prevalence of antidepressant prescriptions in over 600 neighbourhoods in London over a period of three years. We find the distribution of effects is approximately normal, centred on a small negative effect on prescriptions with increases in the availability of sporting facilities, on average. We assess the procedure through some standard quantitative metrics as well as matching on synthetic data generated by modelling the real data. This approach opens the door to fast and inexpensive alternatives to quantify and continuously monitor effects of the neighborhood built environment on population health.","Title: Passive mobile sensing and psychological traits for large scale mood prediction\nYear: 2019\n\nAbstract: Experience sampling has long been the established method to sample people's mood in order to assess their mental state. Smartphones start to be used as experience sampling tools for mental health state as they accompany individuals during their day and can therefore gather in-the-moment data. However, the granularity of the data needs to be traded off with the level of interruption these tools introduce. As a consequence the data collected with this technique is often sparse. This has been obviated by the use of passive sensing in addition to mood reports, however, this adds additional noise.\n\nIn this paper we show that psychological traits collected through one-off questionnaires combined with passively collected sensing data (movement from the accelerometer and noise levels from the microphone) can be used to detect individuals whose general mood deviates from the common relaxed characteristic of the general population. By using the reported mood as a classification target we show how to design models that depend only on passive sensors and one-off questionnaires, without bothering users with tedious experience sampling. We validate our approach by using a large dataset of mood reports and passive sensing data collected in the wild with tens of thousands of participants, finding that the combination of these modalities achieves the best classification performance, and that passive sensing yields a +5% boost in accuracy. We also show that sensor data collected for a week performs better than single days for this task. We discuss feature extraction techniques and appropriate classifiers for this kind of multimodal data, as well as overfitting shortcomings of using deep learning to handle static and dynamic features. We believe these findings have significant implications for mobile health applications that can benefit from the correct modeling of passive sensing along with extra user metadata.","Title: Topic-Enhanced Memory Networks for Personalised Point-of-Interest Recommendation.\nYear: 2019\n\nAbstract: Point-of-Interest (POI) recommender systems play a vital role in people's lives by recommending unexplored POIs to users and have drawn extensive attention from both academia and industry. Despite their value, however, they still suffer from the challenges of capturing complicated user preferences and fine-grained user-POI relationship for spatio-temporal sensitive POI recommendation. Existing recommendation algorithms, including both shallow and deep approaches, usually embed the visiting records of a user into a single latent vector to model user preferences: this has limited power of representation and interpretability. In this paper, we propose a novel topic-enhanced memory network (TEMN), a deep architecture to integrate the topic model and memory network capitalising on the strengths of both the global structure of latent patterns and local neighbourhood-based features in a nonlinear fashion. We further incorporate a geographical module to exploit user-specific spatial preference and POI-specific spatial influence to enhance recommendations. The proposed unified hybrid model is widely applicable to various POI recommendation scenarios. Extensive experiments on real-world WeChat datasets demonstrate its effectiveness (improvement ratio of 3.25% and 29.95% for context-aware and sequential recommendation, respectively). Also, qualitative analysis of the attention weights and topic modeling provides insight into the model's recommendation process and results.","Title: Sequence Multi-task Learning to Forecast Mental Wellbeing from Sparse Self-reported Data\nYear: 2019\n\nAbstract: Smartphones have started to be used as self reporting tools for mental health state as they accompany individuals during their days and can therefore gather temporally fine grained data. However, the analysis of self reported mood data offers challenges related to non-homogeneity of mood assessment among individuals due to the complexity of the feeling and the reporting scales, as well as the noise and sparseness of the reports when collected in the wild. In this paper, we propose a new end-to-end ML model inspired by video frame prediction and machine translation, that forecasts future sequences of mood from previous self-reported moods collected in the real world using mobile devices. Contrary to traditional time series forecasting algorithms, our multi-task encoder-decoder recurrent neural network learns patterns from different users, allowing and improving the prediction for users with limited number of self-reports. Unlike traditional feature-based machine learning algorithms, the encoder-decoder architecture enables to forecast a sequence of future moods rather than one single step. Meanwhile, multi-task learning exploits some unique characteristics of the data (mood is bi-dimensional), achieving better results than when training single-task networks or other classifiers.\n\nOur experiments using a real-world dataset of 33,000 user-weeks revealed that (i) 3 weeks of sparsely reported mood is the optimal number to accurately forecast mood, (ii) multi-task learning models both dimensions of mood \"valence and arousal\" with higher accuracy than separate or traditional ML models, and (iii) mood variability, personality traits and day of the week play a key role in the performance of our model. We believe this work provides psychologists and developers of future mobile mental health applications with a ready-to-use and effective tool for early diagnosis of mental health issues at scale.","Title: Segmentation-free Heart Pathology Detection Using Deep Learning\nYear: 2021\n\nAbstract: Cardiovascular (CV) diseases are the leading cause of death in the world, and auscultation is typically an essential part of a cardiovascular examination. The ability to diagnose a patient based on their heart sounds is a rather difficult skill to master. Thus, many approaches for automated heart auscultation have been explored. However, most of the previously proposed methods involve a segmentation step, the performance of which drops significantly for high pulse rates or noisy signals. In this work, we propose a novel segmentation-free heart sound classification method. Specifically, we apply discrete wavelet transform to denoise the signal, followed by feature extraction and feature reduction. Then, Support Vector Machines and Deep Neural Networks are utilised for classification. On the PASCAL heart sound dataset our approach showed superior performance compared to others, achieving 81% and 96% precision on normal and murmur classes, respectively. In addition, for the first time, the data were further explored under a user-independent setting, where the proposed method achieved 92% and 86% precision on normal and murmur, demonstrating the potential of enabling automatic murmur detection for practical use.","Title: Earables for Detection of Bruxism: a Feasibility Study\nYear: 2021\n\nAbstract: ABSTRACTBruxism is a disorder characterised by teeth grinding and clenching, and many bruxism sufferers are not aware of this disorder until their dental health professional notices permanent teeth wear. Stress and anxiety are often listed among contributing factors impacting bruxism exacerbation, which may explain why the COVID-19 pandemic gave rise to a bruxism epidemic. It is essential to develop tools allowing for the early diagnosis of bruxism in an unobtrusive manner. This work explores the feasibility of detecting bruxism-related events using earables in a mimicked in-the-wild setting. Using inertial measurement unit for data collection, we utilise traditional machine learning for teeth grinding and clenching detection. We observe superior performance of models based on gyroscope data, achieving an 88% and 66% accuracy on grinding and clenching activities, respectively, in a controlled environment, and 76% and 73% on grinding and clenching, respectively, in an in-the-wild environment.","Title: FastICARL - Fast Incremental Classifier and Representation Learning with Efficient Budget Allocation in Audio Sensing Applications.\nYear: 2021\n\nAbstract: Various incremental learning (IL) approaches have been proposed to help deep learning models learn new tasks/classes continuously without forgetting what was learned previously (i.e., avoid catastrophic forgetting). With the growing number of deployed audio sensing applications that need to dynamically incorporate new tasks and changing input distribution from users, the ability of IL on-device becomes essential for both efficiency and user privacy. However, prior works suffer from high computational costs and storage demands which hinders the deployment of IL on-device. In this work, to overcome these limitations, we develop an end-to-end and on-device IL framework, FastICARL, that incorporates an exemplar-based IL and quantization in the context of audio-based applications. We first employ k-nearest-neighbor to reduce the latency of IL. Then, we jointly utilize a quantization technique to decrease the storage requirements of IL. We implement FastICARL on two types of mobile devices and demonstrate that FastICARL remarkably decreases the IL time up to 78-92% and the storage requirements by 2-4 times without sacrificing its performance. FastICARL enables complete on-device IL, ensuring user privacy as the user data does not need to leave the device.","Title: OESense: employing occlusion effect for in-ear human sensing\nYear: 2021\n\nAbstract: ABSTRACTSmart earbuds are recognized as a new wearable platform for personal-scale human motion sensing. However, due to the interference from head movement or background noise, commonly-used modalities (e.g. accelerometer and microphone) fail to reliably detect both intense and light motions. To obviate this, we propose OESense, an acoustic-based in-ear system for general human motion sensing. The core idea behind OESense is the joint use of the occlusion effect (i.e., the enhancement of low-frequency components of bone-conducted sounds in an occluded ear canal) and inward-facing microphone, which naturally boosts the sensing signal and suppresses external interference. We prototype OESense as an earbud and evaluate its performance on three representative applications, i.e., step counting, activity recognition, and hand-to-face gesture interaction. With data collected from 31 subjects, we show that OESense achieves 99.3% step counting recall, 98.3% recognition recall for 5 activities, and 97.0% recall for five tapping gestures on human face, respectively. We also demonstrate that OESense is compatible with earbuds' fundamental functionalities (e.g. music playback and phone calls). In terms of energy, OESense consumes 746 mW during data recording and recognition and it has a response latency of 40.85 ms for gesture recognition. Our analysis indicates such overhead is acceptable and OESense is potential to be integrated into future earbuds.","Title: Anticipatory Detection of Compulsive Body-focused Repetitive Behaviors with Wearables\nYear: 2021\n\nAbstract: Body-focused repetitive behaviors (BFRBs), like face-touching or skin-picking, are hand-driven behaviors which can damage one's appearance, if not identified early and treated. Technology for automatic detection is still under-explored, with few previous works being limited to wearables with single modalities (e.g., motion). Here, we propose a multi-sensory approach combining motion, orientation, and heart rate sensors to detect BFRBs. We conducted a feasibility study in which participants (N=10) were exposed to BFRBs-inducing tasks, and analyzed 380 mins of signals(1) under an extensive evaluation of sensing modalities, cross-validation methods, and observation windows. Our models achieved an AUC > 0.90 in distinguishing BFRBs, which were more evident in observation windows 5 mins prior to the behavior as opposed to 1-min ones. In a follow-up qualitative survey, we found that not only the timing of detection matters but also models need to be context-aware, when designing just-in-time interventions to prevent BFRBs.","Title: PilotEar: Enabling In-ear Inertial Navigation\nYear: 2021\n\nAbstract: ABSTRACT Navigation systems are used daily. While different types of navigation systems exist, inertial navigation systems (INS) have favorable properties for some wearables which, for battery and form factors may not be able to use GPS. Earables (aka ear-worn wearables) are living a momentum both as leisure devices, and sensing and computing platforms. The inherent high signal to noise ratio (SNR) of ear-collected inertial data, due to the vibration dumping of the musculoskeletal system; combined with the fact that people typically wear a pair of earables (one per ear) could offer significant accuracy when tracking head movements, leading to potential improvements for inertial navigation. Hence, in this work, we investigate and propose PilotEar, the first end-to-end earable-based inertial navigation system, achieving an average tracking drift of for one earable and for two earables.","Title: Enabling On-Device Smartphone GPU based Training: Lessons Learned\nYear: 2022\n\nAbstract: Deep Learning (DL) has shown impressive performance in many mobile applications. Most existing works have focused on reducing the computational and resource overheads of running Deep Neural Networks (DNN) inference on resource-constrained mobile devices. However, the other aspect of DNN operations, i.e. training (forward and backward passes) on smartphone GPUs, has received little attention thus f...","Title: Breaking away from labels: The promise of self-supervised machine learning in intelligent health\nYear: 2022\n\nAbstract: Medicine is undergoing an unprecedented digital transformation, as massive amounts of health data are being produced, gathered, and curated, ranging from in-hospital (e.g., intensive care unit [ICU]) to person-generated data (wearables). Annotating all these data for training purposes in order to feed to deep learning models for pattern recognition is impractical. Here, we discuss some exciting recent results of self-supervised learning (SSL) applications to high-resolution health signals. These examples leverage unlabeled data to learn meaningful representations that can generalize to situations where the ground truth is inadequate or simply infeasible to collect due to the high burden or associated costs. The most prominent bottleneck of deep learning today is access to labeled, carefully curated datasets, and self-supervision on health signals opens up new possibilities to eliminate data silos through general-purpose models that can transfer to low-resource environments and tasks.","Title: YONO: Modeling Multiple Heterogeneous Neural Networks on Microcontrollers\nYear: 2022\n\nAbstract: Internet of Things (IoT) systems provide large amounts of data on all aspects of human behavior. Machine learning techniques, especially deep neural networks (DNN), have shown promise in making sense of this data at a large scale. Also, the research community has worked to reduce the computational and resource demands of DNN to compute on low-resourced micro controllers (MCUs). However, most of the current work in embedded deep learning focuses on solving a single task efficiently, while the multi-tasking nature and applications of IoT devices demand systems that can handle a diverse range of tasks (such as activity, gesture, voice, and context recognition) with input from a variety of sensors, simultaneously. In this paper, we propose YONO, a product quantization (PQ) based approach that compresses multiple heterogeneous models and enables in-memory model execution and model switching for dissimilar multi-task learning on MCUs. We first adopt PQ to learn codebooks that store weights of different models. Also, we propose a novel network optimization and heuristics to maximize the com-pression rate and minimize the accuracy loss. Then, we develop an online component of YONO for efficient model execution and switching between multiple tasks on an MCU at run time without relying on an external storage device. YONO shows remarkable performance as it can compress multiple heterogeneous models with negligible or no loss of accuracy up to 12.37x. Furthermore, YONO's online component enables an efficient execution (latency of 16–159 ms and energy consumption of 3.8-37.9 mJ per operation) and reduces modelloading/switching la-tency and energy consumption by 93.3-94.5% and 93.9-95.0%, respectively, compared to external storage access. Interestingly, YONO can compress various architectures trained with datasets that were not shown during YONO's offline codebook learning phase showing the generalizability of our method. To summarize, YONO shows great potential and opens further doors to enable multi-task learning systems on extremely resource-constrained devices.","Title: Improving Feature Generalizability with Multitask Learning in Class Incremental Learning\nYear: 2022\n\nAbstract: Many deep learning applications, like keyword spotting, require the incorporation of new concepts (classes) over time, referred to as Class Incremental Learning (CIL). The major challenge in CIL is catastrophic forgetting, i.e., preserving as much of the old knowledge as possible while learning new tasks. Various techniques, such as regularization, knowledge distillation, and the use of exemplars, have been proposed to resolve this issue. However, prior works primarily focus on the incremental learning step, while ignoring the optimization during the base model training. We hypothesize that a more transferable and generalizable feature representation from the base model would be beneficial to incremental learning. In this work, we adopt multitask learning during base model training to improve the feature generalizability. Specifically, instead of training a single model with all the base classes, we decompose the base classes into multiple subsets and regard each of them as a task. These tasks are trained concurrently and a shared feature extractor is obtained for incremental learning. We evaluate our approach on two datasets under various configurations. The results show that our approach enhances the average incremental learning accuracy by up to 5.5%, which enables more reliable and accurate keyword spotting over time. Moreover, the proposed approach can be combined with many existing techniques and provides additional performance gain.","Title: Stress Inference from Abdominal Sounds using Machine Learning.\nYear: 2022\n\nAbstract: Stress is often considered the 21 century's epidemic, affecting more than a third of the globe's population. Long-term exposure to stress has significant side effects on physical and mental health. In this work we propose a methodology for detecting stress using abdominal sounds. For this study, eight participants were either exposed to a stressful (Stroop test) or a relaxing (guided meditation) stimulus for ten days. In total, we collected 104 hours of abdominal sounds using a custom wearable device in a belt form-factor. We explored the effect of various features on the binary stress classification accuracy using traditional machine learning methods. Namely, we observed the impact of using acoustic features on their own, as well as in combination with features representing current mood state, and hand-crafted domain-specific features. After feature extraction and reduction, by utilising a multilayer perceptron classifier model we achieved 77% accuracy in detecting abdominal sounds under stress exposure. Clinical relevance- This feasibility study confirms the link between the gastrointestinal system and stress and uncovers a novel approach for stress inference via abdominal sounds using machine learning.","Title: Towards Adversarial Robustness with Early Exit Ensembles\nYear: 2022\n\nAbstract: Deep learning techniques are increasingly used for decision-making in health applications, however, these can easily be manipulated by adversarial examples across different clinical domains. Their security and privacy vulnerabilities raise concerns about the practical deployment of these systems. The number and variety of the adversarial attacks grow continuously, making it difficult for mitigation approaches to provide effective solutions. Current mitigation techniques often rely on expensive re-training procedures as new attacks emerge. In this paper, we propose a novel adversarial mitigation technique for biosignal classification tasks. Our approach is based on recent findings interpreting early exit neural networks as an ensemble of weight sharing sub-networks. Our experiments on state-of-the-art deep learning models show that early exit ensembles can provide robustness generalizable to various white box and universal adversarial attacks. The approach increases the accuracy of vulnerable deep learning models up to 60 percentage points, while providing adversarial mitigation comparable to adversarial training. This is achieved without previous exposure to the adversarial perturbation or the computational burden of re-training.","Title: Mobile Health With Head-Worn Devices: Challenges and Opportunities\nYear: 2022\n\nAbstract: Monitoring human behavior and health status using mobile devices, a.k.a. Mobile Health, has gained increasing attention from both academia and industry in recent years. It allows imperceptible health tracking from the users and remote health management from the healthcare service providers. Head-worn devices, such as earbuds, glasses, and brain–computer interfaces, exhibit great potential for mobile health due to their advantageous wearing position, the human head, which is motion-resilient and full of human biosignals. Although initial attempts have been conducted for different healthcare applications with head-worn devices, this fast-growing area is still underexplored and retains great promises. With this work, we investigate the most pressing challenges to fully exploit the potential of head-worn devices for mobile health, from the perspective of sensing, computing, and system design. Our exploration reveals key guidelines and lessons to inform future efforts in this space.","Title: Women in Networks: Professor Cecilia Mascolo\nYear: 2022\n\nAbstract: Cecilia Mascolo is Professor of Mobile Systems in the Department of Computer Science and Technology, University of Cambridge, United Kingdom. She is a Director of the Centre for Mobile, Wearable System and Augmented Intelligence and a Fellow of Jesus College Cambridge.","Title: Exploring On-Device Learning Using Few Shots for Audio Classification\nYear: 2022\n\nAbstract: Few shot learning (FSL) improves the generalization of neural network classifiers to unseen classes and tasks using small annotated samples of data. Recently, there have been attempts to apply few shot learning in the audio domain for various applications. However, the focus has been mainly on accuracy. Here, we take a holistic view and investigate various system aspects such as latency, storage and memory requirements of few shot learning methods in addition to improving the accuracy with very deep learning models for the tasks of audio classification. To this end, we not only compare the performance of different few shot learning methods but also, for the first time, design an end-to-end framework for smartphones and wearables which can run such methods completely on-device. Our results indicate the need to collect large datasets with more classes as we show much higher gains can be obtained with very deep learning models on big datasets. Surprisingly, metric-based methods such as ProtoTypical Networks can be realized practically on-device and quantization helps further (50%) in reducing the resource requirements, while having no impact on accuracy for the audio classification tasks."],"string":"[\n \"Title: Mobile Computing Middleware\\nYear: 2002\\n\\nAbstract: Recent advances in wireless networking technologies and the growing success of mobile computing devices, such as laptop computers, third generation mobile phones, personal digital assistants, watches and the like, are enabling new classes of applications that present challeng- ing problems to designers. Mobile devices face temporary loss of network connectivity when they move; they are likely to have scarce resources, such as low battery power, slow CPU speed and little memory; they are required to react to frequent and unannounced changes in the environ- ment, such as high variability of network bandwidth, and in the resources availability. To support designers building mobile applications, research in the field of middleware systems has proliferated. Middleware aims at facilitating communication and coordination of distributed components, concealing complexity raised by mobility from application engineers as much as possible. In this survey, we examine characteristics of mobile distributed systems and distinguish them from their fixed counterpart. We introduce a framework and a categorisation of the various middle- ware systems designed to support mobility, and we present a detailed and comparative review of the major results reached in this field. An analysis of current trends inside the mobile middleware community and a discussion of further directions of research conclude the survey.\",\n \"Title: An ad hoc mobility model founded on social network theory\\nYear: 2004\\n\\nAbstract: Almost all work on mobile ad hoc networks relies on simulations, which, in turn, rely on realistic movement models for their credibility. Since there is a total absence of realistic data in the public domain, synthetic models for movement pattern generation must be used and the most widely used models are currently very simplistic, the focus being ease of implementation rather than soundness of foundation. Whilst it would be preferable to have models that better reflect the movement of real users, it is currently impossible to validate any movement model against real data. However, it is lazy to conclude from this that all models are equally likely to be invalid so any will do.We note that movement is strongly affected by the needs of humans to socialise in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled, and that are likely to bias their movement patterns. Thus, we propose a new mobility model that is founded on social network theory, because this has empirically been shown to be useful as a means of describing human relationships. In particular, the model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This grouping is only then mapped to a topographical space, with topography biased by the strength of social tie.We discuss the implementation of this mobility model and we evaluate emergent properties of the generated networks. In particular, we show that grouping mechanism strongly influences the probability distribution of the average degree (i.e., the average number of neighbours of a host) in the simulated network.\",\n \"Title: Evaluating context information predictability for autonomic communication\\nYear: 2006\\n\\nAbstract: Delay tolerant and mobile ad hoc networks present considerable challenges to the development of protocols and systems. In particular, the challenge of being able to cope with their variability is an important one: sometimes the rate at which these systems change in terms of context (such as topology, collocation duration and availability and quality of the local resources) is very high and these changes are unpredictable. Knowledge of context could be used to improve the performance of such systems. For example, context information may be extremely useful to make routing decisions. Some recent approaches have successfully exploited context and prediction on future context condition to improve performance, for instance in terms of delivery ratio and delay. In this paper, we present a model of predictability of context information and the design of a generic component implementing it. The component can be used to decide if (or in which measure) context is predictable. The model is based on the analysis of the time series representing the context information. In order to show how the component can be used in practice, we describe its integration in our context-aware adaptive routing (CAR) protocol\",\n \"Title: Adaptive resource discovery for ubiquitous computing\\nYear: 2004\\n\\nAbstract: The terms pervasive and ubiquitous computing are used to describe a smart space populated by hundreds of intelligent devices that are embedded in their surroundings. Characteristically, ubiquitous computing devices must blend into the background, unobtrusively collaborating to provide value-added services for users. Services are thus essential to the success of this technology and, as a result, both service discovery and service management will play a vital role in generating the revenue stream that is a prerequisite for sustainable ubiquitous deployment. On the one hand, the services provided should be evident by their richness and variety and on the other, the complexity inherent in the environment must be hidden from users. In this paper, we describe RUBI, a resource discovery framework for ubiquitous computing. RUBI represents a novel approach to resource discovery, because the primacy of the need for adaptive autonomic behaviour is established within its design.\",\n \"Title: Wildlife and environmental monitoring using RFID and WSN technology\\nYear: 2009\\n\\nAbstract: Wireless Sensor Networks enable scientists to collect information about the environment with a granularity unseen before, while providing numerous challenges to software designers. Since sensor devices are often powered by small batteries, which take considerable effort to replace, it is of major importance to use energy carefully. We present two efficient ways of extending the lifetime of such systems: 1. an adaptive duty cycling protocol and 2. an adaptive data management protocol. Further, we present some details of our deployed sensor network in Wytham Woods, Oxfordshire.\",\n \"Title: Smartphones for Large-Scale Behavior Change Interventions\\nYear: 2013\\n\\nAbstract: Equipped with cutting-edge sensing technology and high-end processors, smartphones can unobtrusively sense human behavior and deliver feedback and behavioral therapy. The authors discuss two applications for behavioral monitoring and change and present UBhave, the first holistic platform for large-scale digital behavior change intervention.\",\n \"Title: The SATIN Component System-A Metamodel for Engineering Adaptable Mobile Systems\\nYear: 2006\\n\\nAbstract: Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, and more capable. We argue that mobile systems should be able to adapt to changing requirements and execution environments. Adaptation requires the ability to reconfigure the deployed code base on a mobile device. Such reconfiguration is considerably simplified if mobile applications are component-oriented rather than monolithic blocks of code. We present the satin (System Adaptation Targeting Integrated Networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives to reconfigure the software system by dynamically transferring code. The metamodel is implemented in the satin middleware system, a component-based mobile computing middleware that uses the mobility primitives defined in the metamodel to reconfigure both itself and applications that it hosts. We demonstrate the suitability of satin in terms of lightweightedness, flexibility, and reusability for the creation of adaptable mobile systems by using it to implement, port, and evaluate a number of existing and new applications, including an active network platform developed for satellite communication at the European Space Agency. These applications exhibit different aspects of adaptation and demonstrate the flexibility of the approach and the advantages gained.\",\n \"Title: Predictive Resource Scheduling in Computational Grids\\nYear: 2007\\n\\nAbstract: The integration of clusters of computers into computational grids has recently gained the atten- tion of many computational scientists. While considerable progress has been made in building middleware and workflow tools that facilitate the sharing of compute resources, little attention has been paid to grid scheduling and load balancing techniques to reduce job waiting time. Based on a detailed analysis of usage characteristics of an existing grid that involves a large CPU cluster, we observe that grid scheduling decisions can be significantly improved if the characteristics of current usage patterns are understood and extrapolated into the future. We describe a formal framework that uses Kalman filter theory to predict future CPU resource utilisation. This ability to predict future resource utilisation forms the basis for significantly improved grid scheduling decisions. The paper describes the architecture for such a prediction and grid scheduling framework and its implementation using Condor. By way of replicated experiments we demonstrate that the prediction achieves a precision within 15-20% of the utilisation later observed and can significantly improve scheduling quality, compared to approaches that only take into account current load indicators.\",\n \"Title: Characterising temporal distance and reachability in mobile and online social networks\\nYear: 2010\\n\\nAbstract: The analysis of social and technological networks has attracted a lot of attention as social networking applications and mobile sensing devices have given us a wealth of real data. Classic studies looked at analysing static or aggregated networks, i.e., networks that do not change over time or built as the results of aggregation of information over a certain period of time. Given the soaring collections of measurements related to very large, real network traces, researchers are quickly starting to realise that connections are inherently varying over time and exhibit more dimensionality than static analysis can capture. In this paper we propose new temporal distance metrics to quantify and compare the speed (delay) of information diffusion processes taking into account the evolution of a network from a global view. We show how these metrics are able to capture the temporal characteristics of time-varying graphs, such as delay, duration and time order of contacts (interactions), compared to the metrics used in the past on static graphs. We also characterise network reachability with the concepts of in- and out-components. Then, we generalise them with a global perspective by defining temporal connected components. As a proof of concept we apply these techniques to two classes of time-varying networks, namely connectivity of mobile devices and interactions on an online social network.\",\n \"Title: Writing on the clean slate: Implementing a socially-aware protocol in Haggle\\nYear: 2008\\n\\nAbstract: Developing protocols and applications for opportunistic networking can represent a daunting task given the many aspects that must be taken into consideration, such as intermittent connectivity, smart choice among multiple interfaces and intelligent data storage. The implementation of these protocols can be based on generic layer-less communication frameworks that provide programming abstractions for the extraction and analysis of social, colocation and mobility information and allows data exchange by means of heterogeneous devices. We propose Gently, a novel fully implemented solution which combines techniques of context awareness and social knowledge to concretely solve issues related to opportunistic forwarding. More precisely, Gently is born as the combination of the Context-aware Adaptive Routing (CAR) and the socially aware LABEL protocol. We discuss the implementation of our solution on top of the layer-less Haggle framework presenting the key design choices and the lessons learnt.\",\n \"Title: Collecting big datasets of human activity one checkin at a time\\nYear: 2012\\n\\nAbstract: A variety of cutting edge applications for mobile phones exploit the availability of phone sensors to accurately infer the user activity and location to offer more effective services. To validate and evaluate these new applications, appropriate and extensive datasets are needed: in particular, large sets of traces of sensor data (accelerometer, GPS, micro- phone, etc.), labelled with corresponding user activities. So far, such traces have only been collected in short-lived, small-scale setups. The primary reason for this is the difficulty in establishing accurate ground truth information outside the laboratory. Here, we present our vision of a system for large-scale sensor data capturing, leveraging all sensors of todays smart phones, with the aim of generating a large dataset that is augmented with appropriate ground-truth information. The primary challenges that we address consider the energy cost on the mobile device and the incentives for users to keep running the system on their device for longer. We argue for leveraging the concept of the checkin - as successfully introduced in online social networks (e.g. Foursquare) - for collecting activity and context related datasets. With a checkin, a user deliberately provides a small piece of data about their behaviour while enabling the system to adjust sensing and data collection around important activities. In this work we present up2, a mobile app letting users check in to their current activity (e.g., \\\\\\\"waiting for the bus\\\\\\\", \\\\\\\"riding a bicycle\\\\\\\", \\\\\\\"having dinner\\\\\\\"). After a checkin, we use the phone's sensors (GPS, accelerometer, microphone, etc.) to gather data about the user's activity and surrounding. This makes up2 a valuable tool for research in sensor based activity detection.\",\n \"Title: A node discovery service for partially mobile sensor networks\\nYear: 2007\\n\\nAbstract: Wireless Sensor Networks (WSNs) are challenging types of networks where resources can be scarce. In particular, battery is often a very limited resource and the radio interface is the culprit for most of the energy consumption. This makes any discovery of other sensors a difficult task, less cumbersome if sensors are fixed but crucial if (some) sensors start being mobile (such as in wildlife monitoring projects with tagged animals). In this paper we propose a middleware offering node discovery for partially mobile wireless sensor networks, where fixed nodes (sinks), deployed in the environment to monitor the movement of entities, detect those patterns with low power consumption. The approach is based on various machine learning techniques which allows for learning and adapting the wake up strategy of the sinks dynamically. We also report on the evaluation of the approach through simulation and use of real movement traces.\",\n \"Title: A Tale Of Many Cities: Universal Patterns In Human Urban Mobility\\nYear: 2011\\n\\nAbstract: The advent of geographic online social networks such as Foursquare, where users voluntarily signal their current location, opens the door to powerful studies on human movement. In particular the fine granularity of the location data, with GPS accuracy down to 10 meters, and the worldwide scale of Foursquare adoption are unprecedented. In this paper we study urban mobility patterns of people in several metropolitan cities around the globe by analyzing a large set of Foursquare users. Surprisingly, while there are variations in human movement in different cities, our analysis shows that those are predominantly due to different distributions of places across different urban environments. Moreover, a universal law for human mobility is identified, which isolates as a key component the rank-distance, factoring in the number of places between origin and destination, rather than pure physical distance, as considered in some previous works. Building on our findings, we also show how a rank-based movement model accurately captures real human movements in different cities.\",\n \"Title: Don't kill my ads!: balancing privacy in an ad-supported mobile application market\\nYear: 2012\\n\\nAbstract: Application markets have revolutionized the software download model of mobile phones: third-party application developers offer software on the market that users can effortlessly install on their phones. This great step forward, however, also imposes some threats to user privacy: applications often ask for permissions that reveal private information such as the user's location, contacts and messages. While some mechanisms to prevent leaks of user privacy to applications have been proposed by the research community, these solutions fail to consider that application markets are primarily driven by advertisements that rely on accurately profiling the user. In this paper we take into account that there are two parties with conflicting interests: the user, interested in maintaining their privacy and the developer who would like to maximize their advertisement revenue through user profiling. We have conducted an extensive analysis of more than 250,000 applications in the Android market. Our results indicate that the current privacy protection mechanisms are not effective as developers and advert companies are not deterred. Therefore, we designed and implemented a market-aware privacy protection framework that aims to achieve an equilibrium between the developer's revenue and the user's privacy. The proposed framework is based on the establishment of a feedback control loop that adjusts the level of privacy protection on mobile phones, in response to advertisement generated revenue.\",\n \"Title: Adapting asynchronous messaging middleware to ad hoc networking\\nYear: 2004\\n\\nAbstract: The characteristics of mobile environments, with the possibility of frequent disconnections and fluctuating bandwidth, have forced a rethink of traditional middleware. In particular, the synchronous communication paradigms often employed in standard middleware do not appear to be particularly suited to ad hoc environments, in which not even the intermittent availability of a backbone network can be assumed. Instead, asynchronous communication seems to be a generally more suitable paradigm for such environments. Message oriented middleware for traditional systems has been developed and used to provide an asynchronous paradigm of communication for distributed systems, and, recently, also for some specific mobile computing systems. In this paper, we present our experience in designing, implementing and evaluating EMMA (Epidemic Messaging Middleware for Ad hoc networks), an adaptation of Java Message Service (JMS) for mobile ad hoc environments. We discuss in detail the design challenges and some possible solutions, showing a concrete example of the feasibility and suitability of the application of the asynchronous paradigm in this setting and outlining a research roadmap for the coming years.\",\n \"Title: Exploiting reflection in mobile computing middleware\\nYear: 2002\\n\\nAbstract: The increasing popularity of portable devices and recent advances in wireless networking technologies facilitate the engineering of new classes of applications, which present challenging problems to designers. Mobile devices face temporary and unannounced loss of network connectivity when they are moved, they are likely to have scarce resources, and they are required to react to frequent changes in the environment. To accommodate these new requirements imposed by mobility, middleware platforms for mobile computing must be capable of both deployment-time configurability and run-time reconfigurability. We illustrate how reflective techniques can be exploited by middleware designers to address these requirements. We discuss two complementary approaches: CARISMA, where reflection is used to support dynamic adaptation of middleware behaviour to changes in context, and ReMMoC, which uses reflection to accommodate heterogeneity requirements imposed by both applications and underlying device platforms.\",\n \"Title: Adaptable Mobile Applications: Exploiting Logical Mobility in Mobile Computing\\nYear: 2003\\n\\nAbstract: An increasing number of applications is being written for mobile hosts, such as laptop computers, mobile phones, PDAs etc. These applications are usually monolithic, featuring very limited interoperability and context-awareness and are usually difficult to deploy and update. Application engineers have to deal with a very dynamic set of environments that these applications are in contact with and it is becoming increasingly difficult to design an application that will be able to cater to all the user's needs in those environments. This new setting forces a shift from design-time to run-time effort in developing software systems. To solve these problems and to allow a new class of ubiquitous and adaptable applications to be built, we have designed and implemented SATIN, a middleware system that allows the flexible use of logical mobility techniques by applications running on mobile hosts which are connected to very different networks. In this paper we describe our approach and show how SATIN can be used to deploy and update applications on mobile devices easily and efficiently.\",\n \"Title: Evaluating Temporal Robustness of Mobile Networks\\nYear: 2013\\n\\nAbstract: The application of complex network models to communication systems has led to several important results: nonetheless, previous research has often neglected to take into account their temporal properties, which in many real scenarios play a pivotal role. At the same time, network robustness has come extensively under scrutiny. Understanding whether networked systems can undergo structural damage and yet perform efficiently is crucial to both their protection against failures and to the design of new applications. In spite of this, it is still unclear what type of resilience we may expect in a network which continuously changes over time. In this work, we present the first attempt to define the concept of temporal network robustness: we describe a measure of network robustness for time-varying networks and we show how it performs on different classes of random models by means of analytical and numerical evaluation. Finally, we report a case study on a real-world scenario, an opportunistic vehicular system of about 500 taxicabs, highlighting the importance of time in the evaluation of robustness. Particularly, we show how static approximation can wrongly indicate high robustness of fragile networks when adopted in mobile time-varying networks, while a temporal approach captures more accurately the system performance.\",\n \"Title: Evolution of a location-based online social network: analysis and models\\nYear: 2012\\n\\nAbstract: Connections established by users of online social networks are influenced by mechanisms such as preferential attachment and triadic closure. Yet, recent research has found that geographic factors also constrain users: spatial proximity fosters the creation of online social ties. While the effect of space might need to be incorporated to these social mechanisms, it is not clear to which extent this is true and in which way this is best achieved. To address these questions, we present a measurement study of the temporal evolution of an online location-based social network. We have collected longitudinal traces over 4 months, including information about when social links are created and which places are visited by users, as revealed by their mobile check-ins. Thanks to this fine-grained temporal information, we test and compare whether different probabilistic models can explain the observed data adopting an approach based on likelihood estimation, quantitatively comparing their statistical power to reproduce real events. We demonstrate that geographic distance plays an important role in the creation of new social connections: node degree and spatial distance can be combined in a gravitational attachment process that reproduces real traces. Instead, we find that links arising because of triadic closure, where users form new ties with friends of existing friends, and because of common focus, where connections arise among users visiting the same place, appear to be mainly driven by social factors. We exploit our findings to describe a new model of network growth that combines spatial and social factors. We extensively evaluate our model and its variations, demonstrating that it is able to reproduce the social and spatial properties observed in our traces. Our results offer useful insights for systems that take advantage of the spatial properties of online social services.\",\n \"Title: On the Effectiveness of an Opportunistic Traffic Management System for Vehicular Networks\\nYear: 2011\\n\\nAbstract: Road congestion results in a huge waste of time and productivity for millions of people. A possible way to deal with this problem is to have transportation authorities distribute traffic information to drivers, which, in turn, can decide (or be aided by a navigator) to route around congested areas. Such traffic information can be gathered by relying on static sensors placed at specific road locations (e.g., induction loops and video cameras) or by having single vehicles report their location, speed, and travel time. While the former approach has been widely exploited, the latter has come about only more recently; consequently, its potential is less understood. For this reason, in this paper, we study a realistic test case that allows the evaluation of the effectiveness of such a solution. As part of this process, (a) we designed a system that allows vehicles to crowd-source traffic information in an ad hoc manner, allowing them to dynamically reroute based on individually collected traffic information; (b) we implemented a realistic network-mobility simulator that allowed us to evaluate such a model; and (c) we performed a case study that evaluates whether such a decentralized system can help drivers to minimize trip times, which is the main focus of this paper. This study is based on traffic survey data from Portland, OR, and our results indicate that such navigation systems can indeed greatly improve traffic flow. Finally, to test the feasibility of our approach, we implemented our system and ran some real experiments at UCLA's C-Vet test bed.\",\n \"Title: XMIDDLE: information sharing middleware for a mobile environment\\nYear: 2002\\n\\nAbstract: Summary form only given. The capabilities of modern mobile devices enable new classes of applications to exploit the ability to form ad-hoc workgroups and exchange data in a very dynamic fashion. They also present, however, new challenges to application developers, related with the scarcity of resources that need to be exploited efficiently. Moreover network connectivity may be interrupted instantaneously and network bandwidth remains by orders of magnitude lower than in wired networks. To address such issues, we have designed and implemented XMIDDLE, which advances mobile computing middleware approaches by choosing a more powerful underlying data structure (XML) and by supporting offline data manipulation.\",\n \"Title: Open source smartphone libraries for computational social science\\nYear: 2013\\n\\nAbstract: The ubiquity of sensor-rich and computationally powerful smartphones makes them an ideal platform for conducting social and behavioural research. However, building sensor data collection tools remains arduous and challenging: it requires an understanding of the varying sensor programming interfaces as well as the research issues related to building sensor-sampling systems. To alleviate this problem and facilitate the development of social sensing and data collection applications, we are developing a set of open-source smartphone libraries to collect, store and transfer, and query sensor data. Furthermore, we have also developed a library that can trigger notifications based on time or sensor events to assist experience sampling methods. This paper presents these libraries' architecture, initial feedback from developers using it, and a sensing application that we built using them to study daily affect.\",\n \"Title: The importance of being placefriends: discovering location-focused online communities\\nYear: 2012\\n\\nAbstract: Discovering groups of online friends who go to the same physical places has numerous potential applications including privacy management, friend recommendation, and contact grouping as in Google+ circles. Until recently, little information was available about places visited by users of online social networking services, so community detection on the social graph could not take this into account. With the rise of services such as Foursquare, Gowalla, and Facebook Places, where users check in to named venues and share their location with their friends, we now have the right data to make this possible. In this work, we propose a way to extract place-focused communities from the social graph by annotating its edges with check-in information. Using traces from two online social networks with location sharing, we show that we can extract groups of friends who meet face-to-face, with many possible benefits for online social services.\",\n \"Title: Content Source Selection in Bluetooth Networks\\nYear: 2007\\n\\nAbstract: Large scale market penetration of electronic devices equipped with Bluetooth technology now gives the ability to share content (such as music or video clips) between members of the public in a decentralised manner. Achieved using opportunistic connections, formed when they are colocated, in environments where Internet connectivity is expensive or unreliable, such as urban buses, train rides and coffee shops. Most people have a high degree of regularity in their movements (such as a daily commute), including repeated contacts with others possessing similar seasonal movement patterns. We argue that this behaviour can be exploited in connection selection, and outline a system for the identification of long-term companions and sources that have previously provided quality content, in order to maximise the successful receipt of content files. We utilise actual traces and existing mobility models to validate our approach, and show how consideration of the colocation history and the quality of previous data transfers leads to more successful sharing of content in realistic scenarios.\",\n \"Title: CAR: Context-Aware Adaptive Routing for Delay-Tolerant Mobile Networks\\nYear: 2009\\n\\nAbstract: Most of the existing research work in mobile ad hoc networking is based on the assumption that a path exists between the sender and the receiver. On the other hand, applications of decentralised mobile systems are often characterised by network partitions. As a consequence delay tolerant networking research has received considerable attention in the recent years as a means to obviate to the gap between ad hoc network research and real applications. In this paper we present the design, implementation and evaluation of the Context-aware Adaptive Routing (CAR) protocol for delay tolerant unicast communication in intermittently connected mobile ad hoc networks. The protocol is based on the idea of exploiting nodes as carriers of messages among network partitions to achieve delivery. The choice of the best carrier is made using Kalman filter based prediction techniques and utility theory. We discuss the implementation of CAR over an opportunistic networking framework, outlining possible applications of the general principles at the basis of the proposed approach. The large scale performance of the CAR protocol are evaluated using simulations based on a social network founded mobility model, a purely random one and real traces from Dartmouth College.\",\n \"Title: Visualizing Z Notation in HTML Documents\\nYear: 1998\\n\\nAbstract: The use of the WWW as a communication medium for software engineers is limited by the lack of tools for writing, sharing, and verifying formal notations. For instance, the Z specification language has a a rich set of mathematical characters, and requires graphic-rich boxes and schemas for its specifications. It is difficult to integrate Z specifications and text on WWW pages written with the current versions of HTML, and traditional tools are not suited for the task. We present a Java-based...\",\n \"Title: Managing Complex Documents Over the WWW: A Case Study for XML\\nYear: 1999\\n\\nAbstract: The use of the World Wide Web as a communication medium for knowledge engineers and software designers is limited by the lack of tools for writing, sharing, and verifying documents written with design notations. For instance, the Z language has a rich set of mathematical characters, and requires graphic-rich boxes and schemas for structuring a specification document. It is difficult to integrate Z specifications and text on WWW pages written with HTML, and traditional tools are not suited for the task. On the other hand, a newly proposed standard for markup languages, namely XML, allows one to define any set of markup elements; hence, it is suitable for describing any kind of notation. Unfortunately, the proposed standard for rendering XML documents, namely XSL, provides for text-only (although sophisticated) rendering of XML documents, and thus it cannot be used for more complex notations. We present a Java-based tool for applying any notation to elements of XML documents. These XML documents can thus be shown on current-generation WWW browsers with Java capabilities. A complete package for displayingZ specifications has been implemented and integrated with standard text parts. Being a complete rendering engine, text parts andZ specifications can be freely intermixed, and all the standard features of XML (including HTML links and form elements) are available outside and inside Z specifications. Furthermore, the extensibility of our engine allows any additional notations to be supported and integrated with the ones we describe here.\",\n \"Title: Analyzing and Refining an Architectural Style\\nYear: 1997\\n\\nAbstract: Architectural styles have been introduced in [1] in order to classify and analyze software architectures. In that paper, Z was used as a notation to specify and study architectural styles, however some problems remained open concerning specification and analysis of their behavioral properties. In this paper we use a new operational semantics to describe and analyze an architectural style for distributed systems. We give three refinements of a "Message Router" style, useful for describing...\",\n \"Title: CODEWEAVE: Exploring Fine-Grained Mobility of Code\\nYear: 2004\\n\\nAbstract: This paper is concerned with an abstract exploration of code mobility constructs designed for use in settings where the level of granularity associated with the mobile units exhibits significant variability. Units of mobility that are both finer and coarser grained than the unit of execution are examined. To accomplish this, we take the extreme view that every line of code and every variable declaration are potentially mobile, i.e., it may be duplicated or moved from one program context to another on the same host or across the network. We also assume that complex code assemblies may move with equal ease. The result is CODEWEAVE, a model that shows how to develop new forms of code mobility, assign them precise meaning, and facilitate formal verification of programs employing them. The design of CODEWEAVE relies greatly on Mobile UNITY, a notation and proof logic for mobile computing. Mobile UNITY offers a computational milieu for examining a wide range of constructs and semantic alternatives in a clean abstract setting, i.e., unconstrained by compilation and performance considerations traditionally associated with programming language design. Ultimately, the notation offered by CODEWEAVE is given exact semantic definition by means of a direct mapping to the underlying Mobile UNITY model. The abstract and formal treatment of code mobility offered by CODEWEAVE establishes a technical foundation for examining competing proposals and for subsequent integration of some of the mobility constructs both at the language level and within middleware for mobility.\",\n \"Title: Opportunistic spatio-temporal dissemination system for vehicular networks\\nYear: 2007\\n\\nAbstract: Opportunistic dissemination protocols have potentially applications in the domain of vehicular networking, ranging from advertising to emergency/traffic/parking information spreading: one of the characteristics of vehicular networks is that they are often partitioned due to lack of continuity in connectivity among cars or limited coverage of infostations in remote areas. Most available opportunistic, or delay tolerant, networking protocols, however, fail to take into account the peculiarities of vehicular networks. This paper introduces a novel opportunistic event dissemination protocol for vehicular networks. The protocol takes into account the characteristics of these networks in order to dispatch the publications to the subscribers. Furthermore, it uses opportunistic cache and replay mechanisms to deliver the notifications to new subscribers in the area throughout the publication interval. We evaluate our approach through simulation using realistic vehicular traces. We compare our algorithm with a standard epidemic protocol, which offer the best alternative in terms of message delivery, by measuring overhead and delivery over a number of scenarios.\",\n \"Title: MobiS: A Specification Language for Mobile Systems\\nYear: 1999\\n\\nAbstract: New formal languages have been proposed for the specification of mobility aspects of systems and for understanding the recent devised technologies for mobile computing. In this paper we introduce MobiS, a specification language based on a tuple-spaces based model which specifies coordination bymultiset rewriting. We show how MobiS can be flexibly used to specify architectures containing mobile components and give formalization of some common mobility paradigms. We explore the styles we introduce showing how they model the software architecture of a \\\"Purchasing System\\\", a case study in electronic commerce.\",\n \"Title: Sense and sensibility in a pervasive world\\nYear: 2012\\n\\nAbstract: The increasing popularity of location based social services such as Facebook Places, Foursquare and Google Latitude, solicits a new trend in fusing social networking with real-world sensing. The availability of a wide range of sensing technologies in our everyday environment presents an opportunity to further enrich social networking systems with fine-grained real-world sensing. However, the introduction of passive sensing into a social networking application disrupts the traditional, user-initiated input to social services, raising both privacy and acceptability concerns. In this work we present an empirical study of the introduction of a sensor-driven social sharing application within the working environment of a research institution. Our study is based on a real deployment of a system that involves location tracking, conversation monitoring, and interaction with physical objects. By utilizing surveys, interviews and experience sampling techniques, we report on our findings regarding privacy and user experience issues, and significant factors that can affect acceptability of such services by the users. Our results suggest that such systems deliver significant value in the form of self reflection and comparison with others, while privacy concerns are raised primarily by the limited control over the way individuals are projected to their peers.\",\n \"Title: Social and place-focused communities in location-based online social networks\\nYear: 2013\\n\\nAbstract: Thanks to widely available, cheap Internet access and the ubiquity of smartphones,\\nmillions of people around the world now use online location-based social networking\\nservices. Understanding the structural properties of these systems and their dependence\\nupon users’ habits and mobility has many potential applications, including resource\\nrecommendation and link prediction. Here, we construct and characterise social and\\nplace-focused graphs by using longitudinal information about declared social relationships\\nand about users’ visits to physical places collected from a popular online location-based\\nsocial service. We show that although the social and place-focused graphs are constructed\\nfrom the same data set, they have quite different structural properties. We find that the\\nsocial and location-focused graphs have different global and meso-scale structure, and in\\nparticular that social and place-focused communities have negligible overlap.\\nConsequently, group inference based on community detection performed on the social graph\\nalone fails to isolate place-focused groups, even though these do exist in the network. By\\nstudying the evolution of tie structure within communities, we show that the time period\\nover which location data are aggregated has a substantial impact on the stability of\\nplace-focused communities, and that information about place-based groups may be more\\nuseful for user-centric applications than that obtained from the analysis of social\\ncommunities alone.\",\n \"Title: Applications of Temporal Graph Metrics to Real-World Networks\\nYear: 2013\\n\\nAbstract: Real world networks exhibit rich temporal information: friends are added and removed over time in online social networks; the seasons dictate the predator-prey relationship in food webs; and the propagation of a virus depends on the network of human contacts throughout the day. Recent studies have demonstrated that static network analysis is perhaps unsuitable in the study of real world network since static paths ignore time order, which, in turn, results in static shortest paths overestimating available links and underestimating their true corresponding lengths. Temporal extensions to centrality and efficiency metrics based on temporal shortest paths have also been proposed. Firstly, we analyse the roles of key individuals of a corporate network ranked according to temporal centrality within the context of a bankruptcy scandal; secondly, we present how such temporal metrics can be used to study the robustness of temporal networks in presence of random errors and intelligent attacks; thirdly, we study containment schemes for mobile phone malware which can spread via short range radio, similar to biological viruses; finally, we study how the temporal network structure of human interactions can be exploited to effectively immunise human populations. Through these applications we demonstrate that temporal metrics provide a more accurate and effective analysis of real-world networks compared to their static counterparts.\",\n \"Title: Exploiting place features in link prediction on location-based social networks\\nYear: 2011\\n\\nAbstract: Link prediction systems have been largely adopted to recommend new friends in online social networks using data about social interactions. With the soaring adoption of location-based social services it becomes possible to take advantage of an additional source of information: the places people visit. In this paper we study the problem of designing a link prediction system for online location-based social networks. We have gathered extensive data about one of these services, Gowalla, with periodic snapshots to capture its temporal evolution. We study the link prediction space, finding that about 30% of new links are added among \\\"place-friends\\\", i.e., among users who visit the same places. We show how this prediction space can be made 15 times smaller, while still 66% of future connections can be discovered. Thus, we define new prediction features based on the properties of the places visited by users which are able to discriminate potential future links among them. Building on these findings, we describe a supervised learning framework which exploits these prediction features to predict new links among friends-of-friends and place-friends. Our evaluation shows how the inclusion of information about places and related user activity offers high link prediction performance. These results open new directions for real-world link recommendation systems on location-based social networks.\",\n \"Title: Graph Metrics for Temporal Networks.\\nYear: 2013\\n\\nAbstract: Temporal networks, i.e., networks in which the interactions among a set of elementary units change over time, can be modelled in terms of time-varying graphs, which are time-ordered sequences of graphs over a set of nodes. In such graphs, the concepts of node adjacency and reachability crucially depend on the exact temporal ordering of the links. Consequently, all the concepts and metrics proposed and used for the characterisation of static complex networks have to be redefined or appropriately extended to time-varying graphs, in order to take into account the effects of time ordering on causality. In this chapter we discuss how to represent temporal networks and we review the definitions of walks, paths, connectedness and connected components valid for graphs in which the links fluctuate over time. We then focus on temporal node-node distance, and we discuss how to characterise link persistence and the temporal small-world behaviour in this class of networks. Finally, we discuss the extension of classic centrality measures, including closeness, betweenness and spectral centrality, to the case of time-varying graphs, and we review the work on temporal motifs analysis and the definition of modularity for temporal graphs.\",\n \"Title: The Call of the Crowd: Event Participation in Location-based Social Services.\\nYear: 2014\\n\\nAbstract: Understanding the social and behavioral forces behind event participation is not only interesting from the viewpoint of social science, but also has important applications in the design of personalized event recommender systems. This paper takes advantage of data from a widely used location-based social network, Foursquare, to analyze event patterns in three metropolitan cities. We put forward several hypotheses on the motivating factors of user participation and confirm that social aspects play a major role in determining the likelihood of a user to participate in an event. While an explicit social filtering signal accounting for whether friends are attending dominates the factors, the popularity of an event proves to also be a strong attractor. Further, we capture an implicit social signal by performing random walks in a high dimensional graph that encodes the place type preferences of friends and that proves especially suited to identify relevant niche events for users. Our findings on the extent to which the various temporal, spatial and social aspects underlie users' event preferences lead us to further hypothesize that a combination of factors better models users' event interests. We verify this through a supervised learning framework. We show that for one in three users in London and one in five users in New York and Chicago it identifies the exact event the user would attend among the pool of suggestions.\",\n \"Title: SociableSense: exploring the trade-offs of adaptive sampling and computation offloading for social sensing\\nYear: 2011\\n\\nAbstract: The interactions and social relations among users in workplaces have been studied by many generations of social psychologists. There is evidence that groups of users that interact more in workplaces are more productive. However, it is still hard for social scientists to capture fine-grained data about phenomena of this kind and to find the right means to facilitate interaction. It is also difficult for users to keep track of their level of sociability with colleagues. While mobile phones offer a fantastic platform for harvesting long term and fine grained data, they also pose challenges: battery power is limited and needs to be traded-off for sensor reading accuracy and data transmission, while energy costs in processing computationally intensive tasks are high. In this paper, we propose SociableSense, a smart phones based platform that captures user behavior in office environments, while providing the users with a quantitative measure of their sociability and that of colleagues. We tackle the technical challenges of building such a tool: the system provides an adaptive sampling mechanism as well as models to decide whether to perform computation of tasks, such as the execution of classification and inference algorithms, locally or remotely. We perform several micro-benchmark tests to fine-tune and evaluate the performance of these mechanisms and we show that the adaptive sampling and computation distribution schemes balance trade-offs among accuracy, energy, latency, and data traffic. Finally, by means of a social psychological study with ten participants for two working weeks, we demonstrate that SociableSense fosters interactions among the participants and helps in enhancing their sociability.\",\n \"Title: WILDSENSING: Design and deployment of a sustainable sensor network for wildlife monitoring\\nYear: 2012\\n\\nAbstract: The increasing adoption of wireless sensor network technology in a variety of applications, from agricultural to volcanic monitoring, has demonstrated their ability to gather data with unprecedented sensing capabilities and deliver it to a remote user. However, a key issue remains how to maintain these sensor network deployments over increasingly prolonged deployments. In this article, we present the challenges that were faced in maintaining continual operation of an automated wildlife monitoring system over a one-year period. This system analyzed the social colocation patterns of European badgers (Meles meles) residing in a dense woodland environment using a hybrid RFID-WSN approach. We describe the stages of the evolutionary development, from implementation, deployment, and testing, to various iterations of software optimization, followed by hardware enhancements, which in turn triggered the need for further software optimization. We highlight the main lessons learned: the need to factor in the maintenance costs while designing the system; to consider carefully software and hardware interactions; the importance of rapid prototyping for initial deployment (this was key to our success); and the need for continuous interaction with domain scientists which allows for unexpected optimizations.\",\n \"Title: A fine-grained model for code mobility\\nYear: 1999\\n\\nAbstract: In this paper we take the extreme view that every line of code is potentially mobile, i.e., may be duplicated and/or moved from one program context to another on the same host or across the network. Our motivation is to gain a better understanding of the range of constructs and issues facing the designer of a mobile code system, in a setting that is abstract and unconstrained by compilation and performance considerations traditionally associated with programming language design. Incidental to our study is an evaluation of the expressive power of Mobile UNITY, a notation and proof logic for mobile computing.\",\n \"Title: Designing mobility models based on social network theory\\nYear: 2007\\n\\nAbstract: Validation of mobile ad hoc network protocols relies almost exclusively on simulation. The value of the validation is, therefore, highly dependent on how realistic the movement models used in the simulations are. Since there is a very limited number of available real traces in the public domain, synthetic models for movement pattern generation must be used. However, most widely used models are currently very simplistic, their focus being ease of implementation rather than soundness of foundation. Simulation results of protocols are often based on randomly generated movement patterns and, therefore, may differ considerably from those that can be obtained by deploying the system in real scenarios. Movement is strongly affected by the needs of humans to socialise or cooperate, in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled and that have been studied in social sciences for years. In this paper we propose a new mobility model founded on social network theory. The model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This clustering is then mapped to a topographical space, with movements influenced by the strength of social ties that may also change in time. We have validated our model with real traces by showing that the synthetic mobility traces are a very good approximation of human movement patterns. The impact of the adoption of the proposed algorithm on the performance of AODV and DSR is also presented and discussed.\",\n \"Title: Exploiting Logical Mobility in Mobile Computing Middleware\\nYear: 2002\\n\\nAbstract: In the past few years, we have witnessed the growth in availability of mobile computing devices, such as mobile phones, personal digital assistants (PDAs), laptop com- puters and the like, combined with the advent of new wireless networking systems, such as 802.11b, Bluetooth, and GSM/GPRS. Users of such devices demand access to networked information and services at all times and loca- tions, and, as such, encounter different networking struc- tures and topologies. The introduction and use of mobile code techniques, from the acceptance of Java applets in web pages, to the creation of mobile agent platforms has demonstrated that it is possible to create dynamic systems that support code migration. We argue that logical mo- bility over physical mobility can offer the flexibility that traditional approaches cannot, helping to provide innova- tive solutions to mobility issues.\",\n \"Title: A hybrid approach for content-based publish/subscribe in vehicular networks\\nYear: 2009\\n\\nAbstract: Content-based information dissemination is emerging as a promising tool to tackle the demands of several applications in vehicular networking, including advertising, traffic and parking notifications, x and emergency announcements. In this paper we describe a protocol for content based information dissemination in hybrid (i.e., partially structureless) vehicular networks. The protocol allows content to ''stick'' to areas where vehicles need to receive it. The vehicle's subscriptions indicate the driver's interests about types of content and are used to filter and route information to affected vehicles. The publications, generated by other vehicles or by central servers, are first routed into the area, then continuously propagated for a specified time interval. The protocol takes advantage of both the infrastructure (i.e., wireless base stations), if this exists, and the decentralised vehicle-to-vehicle communication technologies. To show the feasibility and assess the performance of our approach, we implemented and tested our framework using a small number of vehicles. Furthermore, we run a large scale simulation over a number of realistic vehicular traces based scenarios. Results show that our protocol achieves high message delivery while introducing low overhead, even in scenarios where no infrastructure is available.\",\n \"Title: Centrality prediction in dynamic human contact networks\\nYear: 2012\\n\\nAbstract: Real technological, social and biological networks evolve over time. Predicting their future topology has applications to epidemiology, targeted marketing, network reliability and routing in ad hoc and peer-to-peer networks. The key problem for such applications is usually to identify the nodes that will be in more important positions in the future. Previous researchers had used ad hoc prediction functions. In this paper, we evaluate ways of predicting a node's future importance under three important metrics, namely degree, closeness centrality, and betweenness centrality, using empirical data on human contact networks collected using mobile devices. We find that node importance is highly predictable due to both periodic and legacy effects of human social behaviour, and we design reasonable prediction functions. However human behaviour is not the same in all circumstances: the centrality of students at Cambridge is best correlated both daily and hourly, no doubt due to hourly lecture schedules, while academics at conferences exhibit rather flat closeness centrality, no doubt because conference attendees are generally trying to speak to new people at each break. This highlights the utility of having a number of different metrics for centrality in dynamic networks, so as to identify typical patterns and predict behaviour. We show that the best-performing prediction functions are 25% more accurate on average than simply using the previous centrality value. These prediction functions can be efficiently computed in linear time, and are thus practical for processing dynamic networks in real-time.\",\n \"Title: Analyzing and Animating Declarative Specifications\\nYear: 1996\\n\\nAbstract: Z is a declarative, not executable specification language. We introduce twomethods for formal analysis and testing of behavioral aspects of Z specifications.We define a chemical operational semantics, which supports an abstract executionmodel and some new logic constructs to allow the verification of dynamicproperties. We then describe a parallel animator of Z specifications which automaticallyconstructs distributed prototypes in Shared Prolog directly from arefined specification....\",\n \"Title: Efficient Node Discovery in Mobile Wireless Sensor Networks\\nYear: 2008\\n\\nAbstract: Energy is one of the most crucial aspects in real deployments of mobile sensor networks. As a result of scarce resources, the duration of most real deployments can be limited to just several days, or demands considerable maintenance efforts (e.g., in terms of battery substitution). A large portion of the energy of sensor applications is spent in node discovery as nodes need to periodically advertise their presence and be awake to discover other nodes for data exchange. The optimization of energy consumption, which is generally a hard task in fixed sensor networks, is even harder in mobile sensor networks, where the neighbouring nodes change over time.In this paper we propose an algorithm for energy efficient node discovery in sparsely connected mobile wireless sensor networks. The work takes advantage of the fact that nodes have temporal patterns of encounters and exploits these patterns to drive the duty cycling. Duty cycling is seen as a sampling process and is formulated as an optimization problem. We have used reinforcement learning techniques to detect and dynamically change the times at which a node should be awake as it is likely to encounter other nodes. We have evaluated our work using real human mobility traces, and the paper presents the performance of the protocol in this context.\",\n \"Title: A shared sensor network infrastructure\\nYear: 2010\\n\\nAbstract: An increasing number of sensor networks have been deployed to monitor a variety of conditions and situations. At the same time, more and more applications are starting to rely on the data from sensor networks to provide users with (near) real-time information and conditions. This increasing demand of users for accurate information about natural and surrounding phoenomena is creating a business case for application providers.\",\n \"Title: Los Twindignados: The Rise of the Indignados Movement on Twitter\\nYear: 2012\\n\\nAbstract: Twitter has already become an important facet of the social Web, allowing users and organizations to share their ideas and subscribe to others' updates. Notably, it has been actively used during political events such as the recent elections in Iran, Spain and the USA, or the uprisings in the Middle East, to the extent that it is claimed that revolutions will be tweeted. However such claims are yet to be empirically established. In this work we study an extensive set of millions of tweets themed around the 2011 regional and local elections in Spain and their accompanying civil unrest. Our analysis shows that mainstream political entities were overshadowed on Twitter by grassroots movements discussing alternative points of view, at both regional and national levels. By tracking temporal trends we discover an explosion of interest in the Spanish protests following the establishment of the first protest camps in Madrid. The subsequent spontaneous setting up of similar camps in almost every town in Spain was widely reported at the time, and our spatial analysis quantitatively attests that the protests were indeed widely discussed in all parts of the country. Our results suggest that online social networks serve more as media for interactive engagement between grassroots peers, rather than as platforms for politicians to attract mass attention.\",\n \"Title: Components in time-varying graphs.\\nYear: 2011\\n\\nAbstract: Real complex systems are inherently time-varying. Thanks to new communication systems and novel technologies, today it is possible to produce and analyze social and biological networks with detailed information on the time of occurrence and duration of each link. However, standard graph metrics introduced so far in complex network theory are mainly suited for static graphs, i.e., graphs in which the links do not change over time, or graphs built from time-varying systems by aggregating all the links as if they were concurrent in time. In this paper, we extend the notion of connectedness, and the definitions of node and graph components, to the case of time-varying graphs, which are represented as time-ordered sequences of graphs defined over a fixed set of nodes. We show that the problem of finding strongly connected components in a time-varying graph can be mapped into the problem of discovering the maximal-cliques in an opportunely constructed static graph, which we name the affine graph. It is, therefore, an NP-complete problem. As a practical example, we have performed a temporal component analysis of time-varying graphs constructed from three data sets of human interactions. The results show that taking time into account in the definition of graph components allows to capture important features of real systems. In particular, we observe a large variability in the size of node temporal in-and out-components. This is due to intrinsic fluctuations in the activity patterns of individuals, which cannot be detected by static graph analysis. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697996]\",\n \"Title: Analysing information flows and key mediators through temporal centrality metrics\\nYear: 2010\\n\\nAbstract: The study of influential members of human networks is an important research question in social network analysis. However, the current state-of-the-art is based on static or aggregated representation of the network topology. We argue that dynamically evolving network topologies are inherent in many systems, including real online social and technological networks: fortunately the nature of these systems is such that they allow the gathering of large quantities of finegrained temporal data on interactions amongst the network members. In this paper we propose novel temporal centrality metrics which take into account such dynamic interactions over time. Using a real corporate email dataset we evaluate the important individuals selected by means of static and temporal analysis taking two perspectives: firstly, from a semantic level, we investigate their corporate role in the organisation; and secondly, from a dynamic process point of view, we measure information dissemination and the role of information mediators. We find that temporal analysis provides a better understanding of dynamic processes and a more accurate identification of important people compared to traditional static methods.\",\n \"Title: Satin: A Component Model for Mobile Self Organisation\\nYear: 2004\\n\\nAbstract: We have recently witnessed a growing interest in self organising systems, both in research and in practice. These systems re-organise in response to new or changing conditions in the environment. The need for self organisation is often found in mobile applications; these applications are typically hosted in resource-constrained environments and may have to dynamically reorganise in response to changes of user needs, to heterogeneity and connectivity challenges, as well as to changes in the execution context and physical environment. We argue that physically mobile applications benefit from the use of self organisation primitives. We show that a component model that incorporates code mobility primitives assists in building self organising mobile systems. We present SATIN, a lightweight component model, which represents a mobile system as a set of interoperable local components. The model supports reconfiguration, by offering code migration services. We discuss an implementation of the SATIN middleware, based on the component model and evaluate our work by adapting existing open source software as SATIN components and by building and testing a system that manages the dynamic update of components on mobile hosts.\",\n \"Title: EmotionSense: a mobile phones based adaptive platform for experimental social psychology research\\nYear: 2010\\n\\nAbstract: Today's mobile phones represent a rich and powerful computing platform, given their sensing, processing and communication capabilities. Phones are also part of the everyday life of billions of people, and therefore represent an exceptionally suitable tool for conducting social and psychological experiments in an unobtrusive way. de the ability of sensing individual emotions as well as activities, verbal and proximity interactions among members of social groups. Moreover, the system is programmable by means of a declarative language that can be used to express adaptive rules to improve power saving. We evaluate a system prototype on Nokia Symbian phones by means of several small-scale experiments aimed at testing performance in terms of accuracy and power consumption. Finally, we present the results of real deployment where we study participants emotions and interactions. We cross-validate our measurements with the results obtained through questionnaires filled by the users, and the results presented in social psychological studies using traditional methods. In particular, we show how speakers and participants' emotions can be automatically detected by means of classifiers running locally on off-the-shelf mobile phones, and how speaking and interactions can be correlated with activity and location measures.\",\n \"Title: Contextual dissonance: design bias in sensor-based experience sampling methods\\nYear: 2013\\n\\nAbstract: The Experience Sampling Method (ESM) has been widely used to collect longitudinal survey data from participants; in this domain, smartphone sensors are now used to augment the context-awareness of sampling strategies. In this paper, we study the effect of ESM design choices on the inferences that can be made from participants' sensor data, and on the variance in survey responses that can be collected. In particular, we answer the question: are the behavioural inferences that a researcher makes with a trigger-defined subsample of sensor data biased by the sampling strategy's design? We demonstrate that different single-sensor sampling strategies will result in what we refer to as contextual dissonance: a disagreement in how much different behaviours are represented in the aggregated sensor data. These results are not only relevant to researchers who use the ESM, but call for future work into strategies that may alleviate the biases that we measure.\",\n \"Title: Extending access point connectivity through opportunistic routing in vehicular networks\\nYear: 2010\\n\\nAbstract: Nowadays, the navigation systems available on cars are becoming more and more sophisticated. They greatly improve the experience of drivers and passengers by enabling them to receive map and traffic updates, news feeds, advertisements, media files, etc. Unfortunately, the bandwidth available to each vehicle with the current technology is severely limited. There have been many reports on the inability of 3G networks to cope with large size file downloads, especially in dense and mobile settings. A possible alternative is provided by WiFi access points (APs) that are being installed in several countries along the main routes and in popular areas. Although this approach significantly increases the available bandwidth, it still does not provide a fully satisfactory solution due to the limited transmission range (usually a few hundred meters). In this paper we present a novel routing protocol, based on opportunistic vehicle to vehicle communication, to enable efficient multi-hop routing capabilities between mobile vehicles and APs. Unlike prior work, this protocol fully supports two- way communication, i.e., the traditional vehicle-to-AP as well as the more challenging AP-to-vehicle. We leverage the information offered by the navigation system in terms of final destination and path, to i) route packets to the closest AP and ii) to route replies back to the moving vehicle efficiently.\",\n \"Title: On Nonstationarity of Human Contact Networks\\nYear: 2010\\n\\nAbstract: The measurement and the analysis of the temporal patterns arising in human networks is of fundamental importance to many application domains including targeted advertising, opportunistic routing, resource provisioning (e.g., bandwidth allocation in infrastructured wireless networks) and, more in general, modeling of human social behavior. In this paper we present a novel and exhaustive study of the temporal dynamics of human networks and apply it to different sets of wireless network traces. We consider networks of contacts among users (i.e., peer-to-peer opportunistic networks). We show that we are able to quantify how the amount of information associated to the process evolves over time by using techniques based on time series analysis. We also demonstrate how regular patterns appear only at certain time scales: network dynamics appears nonstationary, in the sense that its statistical description is different at various time scales. These results provide a new methodology to accurately and quantitatively investigate the temporal properties of any type of human interactions and open new directions towards a better understanding of the regular nature of human social behavior.\",\n \"Title: Talking Places: Modelling and Analysing Linguistic Content in Foursquare\\nYear: 2012\\n\\nAbstract: The advent of online social media and the growing popularity of sensor-equipped mobile devices have created a vast landscape of location-aware applications and services. This goldmine of data, including temporal and spatial information of unprecedented granularity, can help researchers gain insights into the behavioural patterns of people at a global scale. Here we analyse the textual content of millions of comments published alongside Foursquare user check-ins. For this, we extend a standard topic modelling approach so that it explicitly takes into account geographic and temporal side information. The framework is applied to Foursquare data and used to detect the dominant topics in the neighbourhoods of a city. In particular, we present the most prominent topics discussed by Foursquare users in New York, London, Chicago and San Francisco. We characterize the topics' spatial coverage and temporal evolution, and we also highlight some cultural idiosyncrasies. Finally, we evaluate the novel spatio-temporal topic model quantitatively. We believe that our model may be a useful tool for social scientists and application developers.\",\n \"Title: NextPlace: a spatio-temporal prediction framework for pervasive systems\\nYear: 2011\\n\\nAbstract: Accurate and fine-grained prediction of future user location and geographical profile has interesting and promising applications including targeted content service, advertisement dissemination for mobile users, and recreational social networking tools for smart-phones. Existing techniques based on linear and probabilistic models are not able to provide accurate prediction of the location patterns from a spatio-temporal perspective, especially for long-term estimation. More specifically, they are able to only forecast the next location of a user, but not his/her arrival time and residence time, i.e., the interval of time spent in that location. Moreover, these techniques are often based on prediction models that are not able to extend predictions further in the future. In this paper we present NextPlace, a novel approach to location prediction based on nonlinear time series analysis of the arrival and residence times of users in relevant places. NextPlace focuses on the predictability of single users when they visit their most important places, rather than on the transitions between different locations. We report about our evaluation using four different datasets and we compare our forecasting results to those obtained by means of the prediction techniques proposed in the literature. We show how we achieve higher performance compared to other predictors and also more stability over time, with an overall prediction precision of up to 90% and a performance increment of at least 50% with respect to the state of the art.\",\n \"Title: Analyzing the Dynamics of a Z Specification\\nYear: 1996\\n\\nAbstract: . We present a method for analyzing the dynamics of a Z documentdescribing a non-sequential system. First a formal operationalsemantics based on the chemical metaphor is given to Z. Then, someUnity-like temporal logic constructs are defined on such a formal operationalsemantics in order to allow the specification and analysis ofdynamic and temporal properties of concurrent systems, such as safetyand liveness properties.1 IntroductionThe introduction of formal methods increased the...\",\n \"Title: Pervasive Analytics and Citizen Science [Guest editors' introduction].\\nYear: 2014\\n\\nAbstract: This special issue aims to explore critical elements of the overall design, user experience, and resulting solutions related to using pervasive computing technologies to inform our understanding of the dynamics of ourselves and our ecosystem, community, and urban landscapes. This issue not only explores pervasive technologies but also reviews practical solutions for improving citizens' health, wellbeing, and everyday lives. Careful attention is also paid to the interplay of social media within this landscape of pervasive analytics and citizen science.\",\n \"Title: Reconfigurable Component-based Middleware for Networked Embedded Systems.\\nYear: 2007\\n\\nAbstract: Next generation embedded systems will be composed of large numbers of heterogeneous devices. These will typically be resource-constrained (such as sensor motes), will use different operating systems, and will be connected through different types of network interfaces. Additionally, they may be mobile and/or form ad-hoc networks with their peers, and will need to be adaptive to changing conditions based on context-awareness. Our focus in this paper is on the provision of a middleware framework for such system environments. Our approach is based on a small and efficient ‘middleware kernel’ which supports highly modularised and customisable component-based middleware services that can be tailored for specific embedded environments, and are runtime reconfigurable to support adaptivity. These services are primarily communications-related but also address a range of other concerns including service discovery and logical mobility. In the paper we provide an overview of our approach, focusing in detail on both the middleware kernel and the services. We also discuss an application scenario in which we are currently applying and evaluating our middleware approach.\",\n \"Title: Model Checking Programmable Router Configurations\\nYear: 2010\\n\\nAbstract: Programmable networks offer the ability to customize router behaviour at run time, thus increasing flexibility of network\\n administration. Programmable network routers are configured using domain-specific languages. In this paper, we describe our\\n approach to defining the syntax and semantics of such a domain-specific language. The ability to evolve router programs dynamically\\n creates potential for misconfigurations. By exploiting domain-specific abstractions, we are able to translate router configurations\\n into Promela and validate them using the Spin model checker, thus providing reasoning support for our domain-specific language.\\n To evaluate our approach we use our configuration language to express the IETF’s Differentiated Services specification and\\n show that industrial-sized DiffServ router configurations can be validated using Spin on a standard PC.\",\n \"Title: EMMA: Epidemic Messaging Middleware for Ad hoc networks\\nYear: 2006\\n\\nAbstract: The characteristics of mobile environments, with the possibility of frequent disconnections and fluctuating bandwidth, have forced a rethink of traditional middleware. In particular, the synchronous communication paradigms often employed in standard middleware do not appear to be particularly suited to ad hoc environments, in which not even the intermittent availability of a backbone network can be assumed. Instead, asynchronous communication seems to be a generally more suitable paradigm for such environments. Message oriented middleware for traditional systems has been developed and used to provide an asynchronous paradigm of communication for distributed systems, and, also for some specific mobile computing systems recently. In this paper, we present our experience in designing, implementing, and evaluating Epidemic Messaging Middleware for Ad hoc networks (EMMA), an adaptation of Java Message Service (JMS) for mobile ad hoc environments, discussing in detail the design challenges and the solutions that have been adopted.\",\n \"Title: SCAR: context-aware adaptive routing in delay tolerant mobile sensor networks\\nYear: 2006\\n\\nAbstract: Sensor devices are being embedded in all sorts of items including vehicles, furniture but also animal and human bodies through health monitors and tagging techniques. The collection of the information generated by these devices is a challenging task as the data results in enormous amounts and the sensors have scarce resources (especially in terms of energy for the forwarding of the data). Fortunately, the data is often delay tolerant and its delivery to the sinks is, in most cases, not time critical.This paper tackles the problem of the delivery of mobile sensor data to sinks. We devise a Sensor Context-Aware Routing protocol (SCAR), which exploits movement and resource prediction techniques to smartly forward data towards the right direction at any point in time. In order to cope with the possibly frequent sensor faults, we also adopt a multi-path routing approach which increases the reliability.\",\n \"Title: A framework for multi-region delay tolerant networking\\nYear: 2008\\n\\nAbstract: Almost all the existing work on routing in delay tolerant networks has focussed on the problem of delivery of messages inside a single region, characterized by the same network infrastructure and namespace. However, many deployment scenarios, especially in developing regions, will probably involve routing among different regions composed of several heterogeneous types of network domains such as WiMAX or satellite networks and ad hoc networks composed of short-range radio enabled devices, like mobile phones with Bluetooth interface. In this paper, we introduce a proposal for inter-region routing based on both probabilistic and deterministic forwarding mechanisms, embedded in an architectural framework able to support it. We also compare our solution to existing approaches in delay tolerant networking, discussing the main requirements and possible solutions, and outlining the open research problems.\",\n \"Title: A Random Walk around the City: New Venue Recommendation in Location-Based Social Networks\\nYear: 2012\\n\\nAbstract: The popularity of location-based social networks available on mobile devices means that large, rich datasets that contain a mixture of behavioral (users visiting venues), social (links between users), and spatial (distances between venues) information are available for mobile location recommendation systems. However, these datasets greatly differ from those used in other online recommender systems, where users explicitly rate items: it remains unclear as to how they capture user preferences as well as how they can be leveraged for accurate recommendation. This paper seeks to bridge this gap with a three-fold contribution. First, we examine how venue discovery behavior characterizes the large check-in datasets from two different location-based social services, Foursquare and Go Walla: by using large-scale datasets containing both user check-ins and social ties, our analysis reveals that, across 11 cities, between 60% and 80% of users' visits are in venues that were not visited in the previous 30 days. We then show that, by making constraining assumptions about user mobility, state-of-the-art filtering algorithms, including latent space models, do not produce high quality recommendations. Finally, we propose a new model based on personalized random walks over a user-place graph that, by seamlessly combining social network and venue visit frequency data, obtains between 5 and 18% improvement over other models. Our results pave the way to a new approach for place recommendation in location-based social systems.\",\n \"Title: The RUNES Middleware for Networked Embedded Systems and its Application in a Disaster Management Scenario\\nYear: 2007\\n\\nAbstract: Due to the inherent nature of their heterogeneity, resource scarcity and dynamism, the provision of middleware for future networked embedded environments is a challeng- ing task. In this paper we present a middleware approach that addresses these key challenges; we also discuss its ap- plication in a realistic networked embedded environment. Our application scenario involves fire management in a road tunnel that is instrumented with networked sensor and actuator devices. These devices are able to reconfigure their behaviour and their information dissemination strate- gies as they become damaged under emergency conditions, and firefighters are able to coordinate their operations and manage sensors and actuators through dynamic reprogram- ming. Our supporting middleware is based on a two-level architecture: the foundation is a language-independent, component-based programming model that is sufficiently minimal to run on any of the devices typically found in net- worked embedded environments. Above this is a layer of software components that offer the necessary middleware functionality. Rather than providing a monolithic middle- ware \\\"layer', we separate orthogonal areas of middleware functionality into self-contained components that can be se- lectively and individually deployed according to current re- source constraints and application needs. Crucially, the set of such components can be updated at runtime to provide the basis of a highly dynamic and reconfigurable system.\",\n \"Title: Where Businesses Thrive: Predicting the Impact of the Olympic Games on Local Retailers through Location-based Services Data.\\nYear: 2014\\n\\nAbstract: The Olympic Games are an important sporting event with notable consequences for the general economic landscape of the host city. Traditional economic assessments focus on the aggregated impact of the event on the national income, but fail to provide micro-scale insights on why local businesses will benefit from the increased activity during the Games. In this paper we provide a novel approach to modeling the impact of the Olympic Games on local retailers by analyzing a dataset mined from a large location-based social service, Foursquare. We hypothesize that the spatial positioning of businesses as well as the mobility trends of visitors are primary indicators of whether retailers will rise their popularity during the event. To confirm this we formulate a retail winners prediction task in the context of which we evaluate a set of geographic and mobility metrics. We find that the proximity to stadiums, the diversity of activity in the neighborhood, the nearby area sociability, as well as the probability of customer flows from and to event places such as stadiums and parks are all vital factors. Through supervised learning techniques we demonstrate that the success of businesses hinges on a combination of both geographic and mobility factors. Our results suggest that location-based social networks, where crowdsourced information about the dynamic interaction of users with urban spaces becomes publicly available, present an alternative medium to assess the economic impact of large scale events in a city.\",\n \"Title: A micro-economic approach to conflict resolution in mobile computing\\nYear: 2002\\n\\nAbstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed mobile applications. These have to adapt to changes in context, such as variations in network bandwidth, exhaustion of battery power or reachability of services on other devices. We show how the construction of adaptive and context-aware mobile applications can be supported using a reflective middleware. The middleware provides software engineers with primitives to describe how context changes are handled using policies. These policies may conflict. In this paper, we classify the different types of conflicts that may arise in mobile computing. We argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which these policy conflicts can be treated. This method uses a micro-economic approach that relies on a particular type of sealed-bid auction.\",\n \"Title: SenShare: transforming sensor networks into multi-application sensing infrastructures\\nYear: 2012\\n\\nAbstract: Sensor networks are typically purpose-built, designed to support a single running application. As the demand for applications that can harness the capabilities of a sensor-rich environment increases, and the availability of sensing infrastructure put in place to monitor various quantities soars, there are clear benefits in a model where infrastructure can be shared amongst multiple applications. This model however introduces many challenges, mainly related to the management of the communication of the same application running on different network nodes, and the isolation of applications within the network. In this work we present SenShare, a platform that attempts to address the technical challenges in transforming sensor networks into open access infrastructures capable of supporting multiple co-running applications. SenShare provides a clear decoupling between the infrastructure and the running application, building on the concept of overlay networks. Each application operates in an isolated environment consisting of an in-node hardware abstraction layer, and a dedicated overlay sensor network. We further report on the deployment of SenShare within our building, which presently supports the operation of multiple sensing applications, including office occupancy monitoring and environmental monitoring.\",\n \"Title: ParkSense: a smartphone based sensing system for on-street parking\\nYear: 2013\\n\\nAbstract: Studies of automotive traffic have shown that on average 30% of traffic in congested urban areas is due to cruising drivers looking for parking. While we have witnessed a push towards sensing technologies to monitor real-time parking availability, instrumenting on-street parking throughout a city is a considerable investment. In this paper, we present ParkSense, a smartphone based sensing system that detects if a driver has vacated a parking spot. ParkSense leverages the ubiquitous Wi-Fi beacons in urban areas for sensing unparking events. It utilizes a robust Wi-Fi signature matching approach to detect driver's return to the parked vehicle. Moreover, it uses a novel approach based on the rate of change of Wi-Fi beacons to sense if the user has started driving. We show that the rate of change of the observed beacons is highly correlated with actual user speed and is a good indicator of whether a user is in a vehicle. Through empirical evaluation, we demonstrate that our approach has a significantly smaller energy footprint than traditional location sensors like GPS and Wi-Fi based positioning while still maintaining sufficient accuracy.\",\n \"Title: Selective code dissemination in mobile wireless sensor networks\\nYear: 2008\\n\\nAbstract: We present a programming model and distributed protocol to reprogram application-defined subsets of nodes in a wireless sensor network (WSN). the protocol operation is rooted in the use of social information inferred from the behavior of the individuals nodes are attached to.\",\n \"Title: Track globally, deliver locally: improving content delivery networks by tracking geographic social cascades\\nYear: 2011\\n\\nAbstract: Providers such as YouTube offer easy access to multimedia content to millions, generating high bandwidth and storage demand on the Content Delivery Networks they rely upon. More and more, the diffusion of this content happens on online social networks such as Facebook and Twitter, where social cascades can be observed when users increasingly repost links they have received from others. In this paper we describe how geographic information extracted from social cascades can be exploited to improve caching of multimedia files in a Content Delivery Network. We take advantage of the fact that social cascades can propagate in a geographically limited area to discern whether an item is spreading locally or globally. This informs cache replacement policies, which utilize this information to ensure that content relevant to a cascade is kept close to the users who may be interested in it. We validate our approach by using a novel dataset which combines social interaction data with geographic information: we track social cascades of YouTube links over Twitter and build a proof-of-concept geographic model of a realistic distributed Content Delivery Network. Our performance evaluation shows that we are able to improve cache hits with respect to cache policies without geographic and social information.\",\n \"Title: XML technologies and software engineering\\nYear: 2001\\n\\nAbstract: No abstract available.\",\n \"Title: A community based mobility model for ad hoc network research\\nYear: 2006\\n\\nAbstract: Validation of mobile ad hoc network protocols relies almost exclusively on simulation. The value of the validation is, therefore, highly dependent on how realistic the movement models used in the simulations are. Since there is a very limited number of available real traces in the public domain, synthetic models for movement pattern generation must be used. However, most widely used models are currently very simplistic, their focus being ease of implementation rather than soundness of foundation. As a consequence, simulation results of protocols are often based on randomly generated movement patterns and, therefore, may differ considerably from those that can be obtained by deploying the system in real scenarios. Movement is strongly affected by the needs of humans to socialise or cooperate, in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled and that have been studied in social sciences for years.In this paper we propose a new mobility model founded on social network theory. The model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This grouping is then mapped to a topographical space, with movements influenced by the strength of social ties that may also change in time. We have validated our model with real traces by showing that the synthetic mobility traces are a very good approximation of human movement patterns.\",\n \"Title: Temporal distance metrics for social network analysis\\nYear: 2009\\n\\nAbstract: The analysis of social and technological networks has attracted a lot of attention as social networking applications and mobile sensing devices have given us a wealth of real data. Classic studies looked at analysing static or aggregated networks, i.e., networks that do not change over time or built as the results of aggregation of information over a certain period of time. Given the soaring collections of measurements related to very large, real network traces, researchers are quickly starting to realise that connections are inherently varying over time and exhibit more dimensionality than static analysis can capture. In this paper we propose new temporal distance metrics to quantify and compare the speed (delay) of information diffusion processes taking into account the evolution of a network from a local and global view. We show how these metrics are able to capture the temporal characteristics of time-varying graphs, such as delay, duration and time order of contacts (interactions), compared to the metrics used in the past on static graphs. As a proof of concept we apply these techniques to two classes of time-varying networks, namely connectivity of mobile devices and e-mail exchanges.\",\n \"Title: Epcast: Controlled Dissemination in Human-Based Wireless Networks Using Epidemic Spreading Models\\nYear: 2007\\n\\nAbstract: Epidemics-inspired techniques have received huge attention in recent years from the distributed systems and networking communities. These algorithms and protocols rely on probabilistic message replication and redundancy to ensure reliable communication. Moreover, they have been successfully exploited to support group communication in distributed systems, broadcasting, multicasting and information dissemination in fixed and mobile networks. However, in most of the existing work, the probability of infection is determined heuristically, without relying on any analytical model. This often leads to unnecessarily high transmission overheads. In this paper we show that models of epidemic spreading in complex networks can be applied to the problem of tuning and controlling the dissemination of information in wireless ad hoc networks composed of devices carried by individuals, i.e., human-based networks. The novelty of our idea resides in the evaluation and exploitation of the structure of the underlying human network for the automatic tuning of the dissemination process in order to improve the protocol performance. We evaluate the results using synthetic mobility models and real human contacts traces.\",\n \"Title: Media sharing based on colocation prediction in urban transport\\nYear: 2008\\n\\nAbstract: People living in urban areas spend a considerable amount of time on public transport, for example, commuting to/from work. During these periods, opportunities for inter-personal networking present themselves, as many members of the public now carry electronic devices equipped with Bluetooth or other wireless technology. Using these devices, individuals can share content (e.g., music, news and video clips) with fellow travellers that are on the same train or bus. Transferring media content takes time; in order to maximise the chances of successful downloads, users should identify neighbours that possess desirable content and who will travel with them for long-enough periods. In this paper, we propose a user-centric prediction scheme that collects historical colocation information to determine the best content sources. The scheme works on the assumption that people have a high degree of regularity in their movements. We first validate this assumption on a real dataset, that consists of traces of people moving in a large city's mass transit system. We then demonstrate experimentally on these traces that our prediction scheme significantly improves communication efficiency, when compared to a memory(history)-less source selection scheme.\",\n \"Title: CTG: a connectivity trace generator for testing the performance of opportunistic mobile systems\\nYear: 2007\\n\\nAbstract: The testing of the performance of opportunistic communication protocols and applications is usually done through simulation as i) deployments are expensive and should be left to the final stage of the development process, and ii) the number of varying parameters in thesesystems is so high that it would be very hard to conduct thorough testing of all the functionality within a single deployment. Therefore, protocols and applications are often plugged into mobility simulators to test their performance; however, until recently, most of the testing has been conducted with random mobility models which do not mirror reality. Furthermore, despite disconnections playing a veryprominent role in the performance of any opportunistic mobile system, most models do not really account for it. A different approach to testing is the use of real traces of movement collected in specific domains as test cases. These cases, however, do not allow for flexible performance testing, as they are specific for a given scenario withfixed connectivity properties. In this paper we propose the Connectivity Trace Generator (CTG), a tool for the automatic generation of connectivity traces, which takes as input real mobility traces and is able to output a set of traces with similar connectivity properties, which can be used as test cases. This allows developers to investigate the impact of the variation of connectivity patterns, number of hosts, and other parameters on the protocol or application under investigation. We use a real case study (the Dartmouth campus connectivity traces) to show how CTG allows protocol developers to play with some connectivity and density parameters so to best conduct performance testing of different aspects of protocols and applications.\",\n \"Title: Hoodsquare: Modeling and Recommending Neighborhoods in Location-Based Social Networks\\nYear: 2013\\n\\nAbstract: Information garnered from activity on location-based social networks can be harnessed to characterize urban spaces and organize them into neighborhoods. We represent geographic points in the city using spatio-temporal information about Foursquare user check-ins and semantic information about places, with the goal of developing features to input into a novel neighborhood detection algorithm. The algorithm first employs a similarity metric that assesses the homogeneity of a geographic area, and then with a simple mechanism of geographic navigation, it detects the boundaries of a city's neighborhoods. The models and algorithms devised are subsequently integrated into a publicly available, map-based tool named Hood square that allows users to explore activities and neighborhoods in cities around the world. Finally, we evaluate Hood square in the context of are commendation application where user profiles are matched to urban neighborhoods. By comparing with a number of baselines, we demonstrate how Hood square can be used to accurately predict the home neighborhood of Twitter users. We also show that we are able to suggest neighborhoods geographically constrained in size, a desirable property in mobile recommendation scenarios for which geographical precision is key.\",\n \"Title: Persistent content-based information dissemination in hybrid vehicular networks\\nYear: 2009\\n\\nAbstract: Content-based information dissemination has a potential number of applications in vehicular networking, including advertising, traffic and parking notifications and emergency announcements. In this paper we describe a protocol for content based information dissemination in hybrid (i.e., partially structureless) vehicular networks. The protocol allows content to ldquostickrdquo to areas where vehicles need to receive it. The vehicle's subscriptions indicate the driver's interests about types of content and are used to filter and route information to affected vehicles. The publications, generated by other vehicles or by central servers, are first routed into the area, then continuously propagated for a specified time interval. The protocol takes advantage of both the infrastructure (i.e., wireless base stations), if this exists, and the decentralized vehicle-to-vehicle communication technologies. We evaluate our approach by simulation over a number of realistic vehicular traces based scenarios. Results show that our protocol achieves high message delivery while introducing low overhead, even in scenarios where no infrastructure is available.\",\n \"Title: An XML-based Middleware for Peer-to-Peer computing\\nYear: 2001\\n\\nAbstract: An increasing number of distributed applications will be written for mobile hosts, such as laptop computers, third generation mobile phones, personal digital assistants, watches and the like, with focus on peer-to-peer collaboration. Application engineers have to deal with a new set of problems caused by mobility, such as low bandwidth, context changes or loss of connectivity. During disconnection, independently from each others, users will typically update local replicas of shared data, possibly generated by peers. The resulting inconsistent replicas need to be reconciled upon re-connection. To support building mobile applications that use both replication and reconciliation over ad-hoc networks, we have designed XMIDDLE, a peer-to-peer middleware that targets mobile computing settings. In this paper we describe XMIDDLE and show how reflection capabilities are used to allow application engineers to influence replication and reconciliation techniques. XMIDDLE enables the transparent sharing of XML documents across heterogeneous mobile peers, allowing online and off-line access to data\",\n \"Title: Far from the eyes, close on the web: impact of geographic distance on online social interactions\\nYear: 2012\\n\\nAbstract: Online friendship connections are often not representative of social relationships or shared interest between users, but merely provide a public display of personal identity. A better picture of online social behaviour can be achieved by taking into account the intensity of communication levels between users, yielding useful insights for service providers supporting this communication. Among the several factors impacting user interactions, geographic distance might be affecting how users communicate with their friends. While spatial proximity appears influencing how people connect to each other even on the Web, the relationship between social interaction and spatial distance remains unexplored. In this work we analyse the relationship between online user interactions and geographic proximity with a detailed study of a large Spanish online social service. Our results show that while geographic distance strongly affects how social links are created, spatial proximity plays a negligible role on user interactions. These findings offer new insights on the interplay between social and spatial factors influencing online user behaviour and open new directions for future research and applications.\",\n \"Title: TACO-DTN: a time-aware content-based dissemination system for delay tolerant networks\\nYear: 2007\\n\\nAbstract: Content dissemination applications are becoming more and more popular on fixed infrastructure: in this paper we introduce TACO-DTN, a content dissemination system which, by virtue of being time-aware in terms of subscriptions and events, is appropriate for delay tolerant networks, where a number of nodes act as infostations, enjoying some form of connectivity to the backbone, and other nodes are mobile devices, reachable sometimes only through intermittent connectivity of carriers. Examples of applications benefiting from such a system could be travel information dissemination systems in large cities (exploiting infostations at bus stops) or on highways, advertisements dissemination at specific times, and information dissemination to remote villages. The approach is based on a novel concept of temporal utility of subscriptions and events. The temporal utility is used to govern the routing of the events to the right infostation (i.e., the one reached by the interested subscribers at the right time), avoiding unnecessary information transfer on slow links and the buffer management, in case buffer limitations are an issue. We give a description of our protocol and discuss its validation through simulation.\",\n \"Title: Geo-spotting: mining online location-based services for optimal retail store placement\\nYear: 2013\\n\\nAbstract: The problem of identifying the optimal location for a new retail store has been the focus of past research, especially in the field of land economy, due to its importance in the success of a business. Traditional approaches to the problem have factored in demographics, revenue and aggregated human flow statistics from nearby or remote areas. However, the acquisition of relevant data is usually expensive. With the growth of location-based social networks, fine grained data describing user mobility and popularity of places has recently become attainable. In this paper we study the predictive power of various machine learning features on the popularity of retail stores in the city through the use of a dataset collected from Foursquare in New York. The features we mine are based on two general signals: geographic, where features are formulated according to the types and density of nearby places, and user mobility, which includes transitions between venues or the incoming flow of mobile users from distant areas. Our evaluation suggests that the best performing features are common across the three different commercial chains considered in the analysis, although variations may exist too, as explained by heterogeneities in the way retail facilities attract users. We also show that performance improves significantly when combining multiple features in supervised learning algorithms, suggesting that the retail success of a business may depend on multiple factors.\",\n \"Title: Distance matters: geo-social metrics for online social networks\\nYear: 2010\\n\\nAbstract: Online Social Networks (OSNs) are increasingly becoming one of the key media of communication over the Internet. The potential of these services as the basis to gather statistics and exploit information about user behavior is appealing and, as a consequence, the number of applications developed for these purposes has been soaring. At the same time, users are now willing to share information about their location, allowing for the study of the role of geographic distance in social ties. In this paper we present a graph analysis based approach to study social networks with geographic information and new metrics to characterize how geographic distance affects social structure. We apply our analysis to four large-scale OSN datasets: our results show that there is a vast portion of users with short-distance links and that clusters of friends are often geographically close. In addition, we demonstrate that different social networking services exhibit different geo-social properties: OSNs based mainly on location-advertising largely foster local ties and clusters, while services used mainly for news and content sharing present more connections and clusters on longer distances. The results of this work can be exploited to improve many classes of systems and a potential vast number of applications, as we illustrate by means of some practical examples.\",\n \"Title: Reflective Middleware Solutions for Context-Aware Applications\\nYear: 2001\\n\\nAbstract: In this paper, we argue that middleware for wired distributed systems cannot be used in a mobile setting, as the principle of transparency that has driven their design runs counter to the new degrees of awareness imposed by mobility. We propose the marriage of reflection and metadata as a means for middleware to give applications dynamic access to information about their execution context. Finally, we describe a conceptual model that provides the basis of our reflective middleware.\",\n \"Title: Evolution and sustainability of a wildlife monitoring sensor network\\nYear: 2010\\n\\nAbstract: As sensor network technologies become more mature, they are increasingly being applied to a wide variety of applications, ranging from agricultural sensing to cattle, oceanic and volcanic monitoring. Significant efforts have been made in deploying and testing sensor networks resulting in unprecedented sensing capabilities. A key challenge has become how to make these emerging wireless sensor networks more sustainable and easier to maintain over increasingly prolonged deployments. In this paper, we report the findings from a one year deployment of an automated wildlife monitoring system for analyzing the social co-location patterns of European badgers (Meles meles) residing in a dense woodland environment. We describe the stages of its evolution cycle, from implementation, deployment and testing, to various iterations of software optimization, followed by hardware enhancements, which in turn triggered the need for further software optimization. We report preliminary descriptive analyses of a subset of the data collected, demonstrating the significant potential our system has to generate new insights into badger behavior. The main lessons learned were: the need to factor in the maintenance costs while designing the system; to look carefully at software and hardware interactions; the importance of a rapid initial prototype deployment (this was key to our success); and the need for continuous interaction with domain scientists which allows for unexpected optimizations.\",\n \"Title: Performance analysis and prediction of physically mobile systems\\nYear: 2007\\n\\nAbstract: The market of portable computational devices is expanding more and more rapidly. The systems created by the interactions of these devices among themselves and with the surrounding infrastructure result in being quite different from existing traditional systems in terms of connectivity, dynamicity and resource availability. As a consequence, existing performance evaluation and prediction techniques appear to be inadequate to the application to mobile systems. While some adaptations have been proposed for systems presenting some logical mobility (i.e., software mobility), very little has been attempted to provide useful performance prediction methodologies for physically mobile systems.In this paper we present a methodology for modeling performance of physically mobile systems: our aim is to provide guidelines for the designer of the system on how particular physical mobility patterns affect the system performance and on how these measures can be taken into account in the early stages of the system development.\",\n \"Title: Selective reprogramming of mobile sensor networks through social community detection\\nYear: 2010\\n\\nAbstract: We target application domains where the behavior of animals or humans is monitored using wireless sensor network (WSN) devices. The code on these devices is updated frequently, as scientists acquire in-field data and refine their hypotheses. Wireless reprogramming is therefore fundamental to avoid the (expensive) re-collection of the devices. Moreover, the code carried by the monitored individuals often depends on their characteristics, e.g., the behavior or preferred habitat. We propose a selective reprogramming approach that simplifies and automates the process of delivering a code update to a target subset of nodes. Target selection is expressed through constraints injected in the WSN, triggering automatic dissemination of code updates whenever verified. Update dissemination relies on a novel protocol exploiting the social behavior of the monitored individuals. We evaluate our approach through simulation, using real-world animal and human traces. The results shows that our protocol is able to capture the social network structure in a way comparable to existing offline algorithms with global knowledge while allowing runtime adaptation to community structure changes, and that existing dissemination approaches based on gossip generate up to three times more network overhead than our socially-aware dissemination.\",\n \"Title: Adaptive routing for intermittently connected mobile ad hoc networks\\nYear: 2005\\n\\nAbstract: The vast majority of mobile ad hoc networking research makes a very large assumption - that communication can only take place between nodes that are simultaneously accessible within the same connected cloud (i.e., that communication is synchronous). In reality, this assumption is likely to be a poor one, particularly for sparsely or irregularly populated environments. We present the context-aware routing (CAR) algorithm. CAR is a novel approach to the provision of asynchronous communication in partially-connected mobile ad hoc networks, based on the intelligent placement of messages. We discuss the details of the algorithm, and then present simulation results demonstrating that it is possible for nodes to exploit context information in making local decisions that lead to good delivery ratios and latencies with small overheads.\",\n \"Title: Understanding robustness of mobile networks through temporal network measures\\nYear: 2011\\n\\nAbstract: The application of complex network theory to communication systems has led to several important results. Nonetheless, previous research has often neglected to take into account their temporal properties, which in many real scenarios play a pivotal role. Mainly because of mobility, transmission delays or protocol design, a communication network should not be considered only as a static entity. At the same time, network robustness has come extensively under scrutiny. Understanding whether networked systems can undergo structural damage and yet perform efficiently is crucial to both their protection against failures and to the design of new applications. In spite of this, it is still unclear what type of resilience we may expect in a network that continuously changes over time. In this work we present the first attempt to define the concept of temporal network robustness: we describe a measure of network robustness for time-varying networks and we show how it performs on different classes of random models by means of analytical and numerical evaluation. Particularly, we show how static approximation can wrongly indicate high robustness of fragile networks when adopted in mobile time-varying networks, while a temporal approach captures more accurately the system performance.\",\n \"Title: A Place-Focused Model for Social Networks in Cities\\nYear: 2013\\n\\nAbstract: The focused organization theory of social ties proposes that the structure of human social networks can be arranged around extra-network foci, which can include shared physical spaces such as homes, workplaces, restaurants, and so on. Until now, this has been difficult to investigate on a large scale, but the huge volume of data available from online location-based social services now makes it possible to examine the friendships and mobility of many thousands of people, and to investigate the relationship between meetings at places and the structure of the social network. In this paper, we analyze a large dataset from Foursquare, the most popular online location-based social network. We examine the properties of city-based social networks, finding that they have common structural properties, and that the category of place where two people meet has very strong influence on the likelihood of their being friends. Inspired by these observations in combination with the focused organization theory, we then present a model to generate city-level social networks, and show that it produces networks with the structural properties seen in empirical data.\",\n \"Title: Tracking serendipitous interactions: how individual cultures shape the office\\nYear: 2014\\n\\nAbstract: In many work environments, serendipitous interactions between members of different groups may lead to enhanced productivity, collaboration and knowledge dissemination. Two factors that may have an influence on such interactions are cultural differences between individuals in highly multicultural workplaces, and the layout and physical spaces of the workplace itself. In this work, we investigate how these two factors may facilitate or hinder inter-group interactions in the workplace. We analyze traces collected using wearable electronic badges to capture face-to-face interactions and mobility patterns of employees in a research laboratory in the UK. We observe that those who interact with people of different roles tend to come from collectivist cultures that value relationships and where people tend to be comfortable with social hierarchies, and that some locations in particular are more likely to host serendipitous interactions, knowledge that could be used by organizations to enhance communication and productivity.\",\n \"Title: Epcast: Controlled Dissemination in Human-based Wireless Networks by means of Epidemic Spreading Models\\nYear: 2007\\n\\nAbstract: Epidemics-inspired techniques have received huge attention in recent years from the distributed systems and networking communi- ties. These algorithms and protocols rely on probabilistic message repli- cation and redundancy to ensure reliable communication. Moreover, they have been successfully exploited to support group communication in dis- tributed systems, broadcasting, multicasting and information dissemina- tion in fixed and mobile networks. However, in most of the existing work, the probability of infection is determined heuristically, without relying on any analytical model. This often leads to unnecessarily high transmission overheads. In this paper we show that models of epidemic spreading in complex networks can be applied to the problem of tuning and controlling the dissemination of information in wireless ad hoc networks composed of devices carried by individuals, i.e., human-based networks. The novelty of our idea resides in the evaluation and exploitation of the structure of the underlying human network for the automatic tuning of the dissemination process in order to improve the protocol performance. We evaluate the results using synthetic mobility models and real human contacts traces.\",\n \"Title: Implementing incremental code migration with XML\\nYear: 2000\\n\\nAbstract: We demonstrate how XML and related technologies can be used for code mobility at any granularity, thus overcoming the restrictions of existing approaches. By not fixing a particular granularity for mobile code, we enable complete programs as well as individual lines of code to be sent across the network. We define the concept of incremental code mobility as the ability to migrate and add, remove, or replace code fragments (i.e., increments) in a remote program. The combination of fine-grained and incremental migration achieves a previously unavailable degree of flexibility. We examine the application of incremental and fine-grained code migration to a variety of domains, including user interface management, application management on mobile thin clients, for example PDAs, and management of distributed documents.\",\n \"Title: Smartphone sensing offloading for efficiently supporting social sensing applications.\\nYear: 2014\\n\\nAbstract: Mobile phones play a pivotal role in supporting ubiquitous and unobtrusive sensing of human activities. However, maintaining a highly accurate record of a user's behavior throughout the day imposes significant energy demands on the phone's battery. In this work, we investigate a new approach that can lead to significant energy savings for mobile applications that require continuous sensing of social activities. This is achieved by opportunistically offloading sensing to sensors embedded in the environment, leveraging sensing that may be available in typical modern buildings (e.g., room occupancy sensors, RFID access control systems). In this article, we present the design, implementation, and evaluation of METIS: an adaptive mobile sensing platform that efficiently supports social sensing applications. The platform implements a novel sensor task distribution scheme that dynamically decides whether to perform sensing on the phone or in the infrastructure, considering the energy consumption, accuracy, and mobility patterns of the user. By comparing the sensing distribution scheme with sensing performed solely on the phone or exclusively on the fixed remote sensors, we show, through benchmarks using real traces, that the opportunistic sensing distribution achieves over 60% and 40% energy savings, respectively. This is confirmed through a real world deployment in an office environment for over a month: we developed a social application over our frameworks, that is able to infer the collaborations and meetings of the users. In this setting the system preserves over 35% more battery life over pure phone sensing.\",\n \"Title: XMILE: An XML Based Approach for Incremental Code Mobility and Update\\nYear: 2002\\n\\nAbstract: The eXtensible Markup Language (XML) was originally defined to represent Web content, but it is increasingly used to define languages, such as XPL, that are used for coding executable algorithms, policies or scripts. XML-related standards, such as XPath and the Document Object Model, permit the flexible manipulation of fragments of XML code, which enables novel code migration and update paradigms. The XMILE approach that we describe in this paper exploits these mechanisms in order to achieve flexible and fine-grained code updates, even without stopping execution. We describe a Java-based prototype that implements XMILE and our experience in using XMILE in the domain of code updates on mobile devices.\",\n \"Title: XMIDDLE: A Data-Sharing Middleware for Mobile Computing\\nYear: 2002\\n\\nAbstract: An increasing number of distributed applications will be written for mobilehosts, such as laptop computers, third generation mobile phones, personaldigital assistants, watches and the like. Application engineers have to dealwith a new set of problems caused by mobility, such as low bandwidth, contextchanges or loss of connectivity. During disconnection, users will typicallyupdate local replicas of shared data independently from each other. Theresulting inconsistent replicas need to be reconciled upon re-connection. Tosupport building mobile applications that use both replication andreconciliation over ad-hoc networks, we have designed xmiddle, a mobilecomputing middleware. In this paper we describe xmiddle and show how it usesreflection capabilities to allow application engineers to influencereplication and reconciliation techniques. xmiddle enables the transparentsharing of XML documents across heterogeneous mobile hosts, allowing on-lineand off-line access to data. We describe xmiddle using a collaborativee-shopping case study on mobile clients.\",\n \"Title: Towards A Mobile Computing Middleware: A Synergy of Reflection and Mobile Code Techniques\\nYear: 2001\\n\\nAbstract: The increasing popularity of wireless devices, such asmobile phones, personal digital assistants, watches and thelike, is enabling new classes of applications that presentchallenging problems to designers. Applications have tobe aware of, and adapt to, frequent variations in the contextof execution, such as fluctuating network bandwidth,decreasing battery power, changes in location or device capabilities,and so on. In this paper, we argue that middlewaresolutions for wired distributed systems cannot be usedin a mobile setting, as the principle of transparency thathas driven their design runs counter to the new degrees ofawareness imposed by mobility. We propose a synergy ofreflection and code mobility as a means for middleware togive applications the desired level of flexibility to react tochanges happening in the environment, including those thathave not necessarily been foreseen by middleware designers.We use the sharing and processing of images as anapplication scenario to highlight the advantages of our approach.\",\n \"Title: Mining users' significant driving routes with low-power sensors\\nYear: 2014\\n\\nAbstract: While there is significant work on sensing and recognition of significant places for users, little attention has been given to users' significant routes. Recognizing these routine journeys, can open doors for the development of novel applications, like personalized travel alerts, and enhancement of user's travel experience. However, the high energy consumption of traditional location sensing technologies, such as GPS or WiFi based localization, is a barrier to passive and ubiquitous route sensing through smartphones. In this paper, we present a passive route sensing framework that continuously monitors a vehicle user solely through a phone's gyroscope and accelerometer. This approach can differentiate and recognize various routes taken by the user by time warping angular speeds experienced by the phone while in transit and is independent of phone orientation and location within the vehicle, small detours and traffic conditions. We compare the route learning and recognition capabilities of this approach with GPS trajectory analysis and show that it achieves similar performance. Moreover, with an embedded co-processor, common to most new generation phones, it achieves energy savings of an order of magnitude over the GPS sensor.\",\n \"Title: Group Colocation Behavior In Technological Social Networks\\nYear: 2014\\n\\nAbstract: We analyze two large datasets from technological networks with location and social data: user location records from an online location-based social networking service, and anonymized telecommunications data from a European cellphone operator, in order to investigate the differences between individual and group behavior with respect to physical location. We discover agreements between the two datasets: firstly, that individuals are more likely to meet with one friend at a place they have not visited before, but tend to meet at familiar locations when with a larger group. We also find that groups of individuals are more likely to meet at places that their other friends have visited, and that the type of a place strongly affects the propensity for groups to meet there. These differences between group and solo mobility has potential technological applications, for example, in venue recommendation in location-based social networks.\",\n \"Title: The architecture of innovation: tracking face-to-face interactions with ubicomp technologies\\nYear: 2014\\n\\nAbstract: The layouts of the buildings we live in shape our everyday lives. In office environments, building spaces affect employees' communication, which is crucial for productivity and innovation. However, accurate measurement of how spatial layouts affect interactions is a major challenge and traditional techniques may not give an objective view. We measure the impact of building spaces on social interactions using wearable sensing devices. We study a single organization that moved between two different buildings, affording a unique opportunity to examine how space alone can affect interactions. The analysis is based on two large scale deployments of wireless sensing technologies: short-range, lightweight RFID tags capable of detecting face-to-face interactions. We analyze the traces to study the impact of the building change on social behavior, which represents a first example of using ubiquitous sensing technology to study how the physical design of two workplaces combines with organizational structure to shape contact patterns.\",\n \"Title: DSP.Ear: leveraging co-processor support for continuous audio sensing on smartphones\\nYear: 2014\\n\\nAbstract: The rapidly growing adoption of sensor-enabled smartphones has greatly fueled the proliferation of applications that use phone sensors to monitor user behavior. A central sensor among these is the microphone which enables, for instance, the detection of valence in speech, or the identification of speakers. Deploying multiple of these applications on a mobile device to continuously monitor the audio environment allows for the acquisition of a diverse range of sound-related contextual inferences. However, the cumulative processing burden critically impacts the phone battery. To address this problem, we propose DSP.Ear -- an integrated sensing system that takes advantage of the latest low-power DSP co-processor technology in commodity mobile devices to enable the continuous and simultaneous operation of multiple established algorithms that perform complex audio inferences. The system extracts emotions from voice, estimates the number of people in a room, identifies the speakers, and detects commonly found ambient sounds, while critically incurring little overhead to the device battery. This is achieved through a series of pipeline optimizations that allow the computation to remain largely on the DSP. Through detailed evaluation of our prototype implementation we show that, by exploiting a smartphone's co-processor, DSP.Ear achieves a 3 to 7 times increase in the battery lifetime compared to a solution that uses only the phone's main processor. In addition, DSP.Ear is 2 to 3 times more power efficient than a naïve DSP solution without optimizations. We further analyze a large-scale dataset from 1320 Android users to show that in about 80-90% of the daily usage instances DSP.Ear is able to sustain a full day of operation (even in the presence of other smartphone workloads) with a single battery charge.\",\n \"Title: OpenStreetCab: Exploiting Taxi Mobility Patterns in New York City to Reduce Commuter Costs.\\nYear: 2015\\n\\nAbstract: The rise of Uber as the global alternative taxi operator has attracted a lot of interest recently. Aside from the media headlines which discuss the new phenomenon, e.g. on how it has disrupted the traditional transportation industry, policy makers, economists, citizens and scientists have engaged in a discussion that is centred around the means to integrate the new generation of the sharing economy services in urban ecosystems. In this work, we aim to shed new light on the discussion, by taking advantage of a publicly available longitudinal dataset that describes the mobility of yellow taxis in New York City. In addition to movement, this data contains information on the fares paid by the taxi customers for each trip. As a result we are given the opportunity to provide a first head to head comparison between the iconic yellow taxi and its modern competitor, Uber, in one of the world's largest metropolitan centres. We identify situations when Uber X, the cheapest version of the Uber taxi service, tends to be more expensive than yellow taxis for the same journey. We also demonstrate how Uber's economic model effectively takes advantage of well known patterns in human movement. Finally, we take our analysis a step further by proposing a new mobile application that compares taxi prices in the city to facilitate traveller's taxi choices, hoping to ultimately to lead to a reduction of commuter costs. Our study provides a case on how big datasets that become public can improve urban services for consumers by offering the opportunity for transparency in economic sectors that lack up to date regulations.\",\n \"Title: CARISMA: context-aware reflective middleware system for mobile applications\\nYear: 2003\\n\\nAbstract: Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed applications that have to adapt to changes in context, such as variations in network bandwidth, battery power, connectivity, reachability of services and hosts, etc. In this paper, we describe CARISMA, a mobile computing middleware which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. The middleware provides software engineers with primitives to describe how context changes should be handled using policies. These policies may conflict. We classify the different types of conflicts that may arise in mobile computing and argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which policy conflicts can be handled; this method uses a microeconomic approach that relies on a particular type of sealed-bid auction. We describe how this method is implemented in the CARISMA middleware architecture and sketch a distributed context-aware application for mobile devices to illustrate how the method works in practice. We show, by way of a systematic performance evaluation, that conflict resolution does not imply undue overheads, before comparing our research to related work and concluding the paper.\",\n \"Title: Introduction\\nYear: 2019\\n\\nAbstract: The tremendous advances in wireless networks, mobile computing, and sensor networks, along with the rapid growth of small, portable and powerful computing devices, offers more and more opportunities for pervasive computing and communications. This topic deals with cutting-edge research in various aspects related to the theory and practice of mobile computing or wireless and mobile networking. These aspects include architectures, algorithms, networks, protocols, modeling and performance issues, data management, and novel applications and services. The aim of this topic is to bring together computer scientists and engineers from both academia and industry working in this exciting and emerging area of pervasive computing and communications, to share their ideas and results with their peers.\",\n \"Title: Q-CAD: QoS and context aware discovery framework for mobile systems\\nYear: 2005\\n\\nAbstract: This paper presents Q-CAD, a resource discovery frame- work that enables pervasive computing applications to dis- cover and select the resource(s) best satisfying the user needs, taking the current execution context and quality-of- service (QoS) requirements into account. The available re- sources are first screened, so that only those suitable to the current execution context of the application will be consid- ered; the shortlisted resources are then evaluated against the QoS needs of the application, and a binding is estab- lished to the best available.\",\n \"Title: Adaptive distributed indexing for spatial queries in sensor networks\\nYear: 2005\\n\\nAbstract: Sensor networks have opened new horizons and opportunities for a variety of environmental monitoring, surveillance and healthcare applications. One of the major tasks of sensor networks is the distributed collection and processing of sensor readings over extended periods of time. We propose an energy- efficient hierarchical indexing approach for spatial data in sensor networks. Our indexing technique allows roaming users to navigate through sensor networks distributed over large geographical areas and to pose spatial queries about the location of the data in the network. The major challenge in designing such indexes is the minimization of the total amount of traffic needed to create and maintain the indexes, which is a function of region activity and the actual query rates. Given the dynamic character of the setting, these parameters might in fact change during the network operation, calling for a very adaptive solution.\",\n \"Title: Opportunistic Mobile Sensor Data Collection with SCAR\\nYear: 2007\\n\\nAbstract: Sensors are now embedded in all sorts of devices (such as phones and PDAs) and attached to many moving things such as robots, vehicles and animals. The collection of data from these mobile sensors presents challenges related to the variability of the topology of the sensor network and the need to limit communication (for energy or bandwidth sav- ing). Fortunately, the data collected, despite considerable, is often delay tolerant and its delivery to the sinks is, in most cases, not time critical. We have devised SCAR, a context aware opportunistic routing protocol which allows efficient routing of sensor data to sinks, through selection of best paths by prediction over movement patterns and current battery level of nodes. In this paper we present the implementation of the protocol in Contiki and validate the approach through the use of the COOJA simulator with mobility traces provided by the Ze- braNet Project. We compare the performance with respect to random choice based dissemination.\",\n \"Title: Seal-2-Seal: A delay-tolerant protocol for contact logging in wildlife monitoring sensor networks\\nYear: 2008\\n\\nAbstract: Sensor networks are now enabling the monitoring of var- ious environmental phenomena with more accuracy than the previous labour intensive and less technological solutions. This paper is concerned with the application of opportunis- tic networking techniques to wildlife monitoring, where the sensors are attached to animals moving in their habitat. We present Seal-2-Seal, a novel protocol for logging of node (i.e., animal) contacts in mobile networks and for dissemi- nation of that information to sinks for further analysis. The protocol utilises an efficient data summary mechanism to reduce the amount of information that needs to be trans- mitted, thus reducing energy consumption. To evaluate the performance of the protocol, we implemented it for the Con- tiki operating system on sensor devices and ran simulations based on real-life mobility traces using the Cooja emulator.\",\n \"Title: The Power of Mobile Computing in a Social Era\\nYear: 2010\\n\\nAbstract: The most powerful trend in mobile computing is that of increased online social activity. To meet users' future expectations, mobile computing researchers must consider current limitations and identify upcoming challenges.\",\n \"Title: Mining User Mobility Features for Next Place Prediction in Location-Based Services\\nYear: 2012\\n\\nAbstract: Mobile location-based services are thriving, providing an unprecedented opportunity to collect fine grained spatio-temporal data about the places users visit. This multi-dimensional source of data offers new possibilities to tackle established research problems on human mobility, but it also opens avenues for the development of novel mobile applications and services. In this work we study the problem of predicting the next venue a mobile user will visit, by exploring the predictive power offered by different facets of user behavior. We first analyze about 35 million check-ins made by about 1 million Foursquare users in over 5 million venues across the globe, spanning a period of five months. We then propose a set of features that aim to capture the factors that may drive users' movements. Our features exploit information on transitions between types of places, mobility flows between venues, and spatio-temporal characteristics of user check-in patterns. We further extend our study combining all individual features in two supervised learning models, based on linear regression and M5 model trees, resulting in a higher overall prediction accuracy. We find that the supervised methodology based on the combination of multiple features offers the highest levels of prediction accuracy: M5 model trees are able to rank in the top fifty venues one in two user check-ins, amongst thousands of candidate items in the prediction list.\",\n \"Title: Mining open datasets for transparency in taxi transport in metropolitan environments\\nYear: 2015\\n\\nAbstract: Abstract Uber has recently been introducing novel practices in urban taxi transport. Journey prices can change dynamically in almost real time and also vary geographically from one area to another in a city, a strategy known as surge pricing. In this paper, we explore the power of the new generation of open datasets towards understanding the impact of the new disruption technologies that emerge in the area of public transport. With our primary goal being a more transparent economic landscape for urban commuters, we provide a direct price comparison between Uber and the Yellow Cab company in New York. We discover that Uber, despite its lower standard pricing rates, effectively charges higher fares on average, especially during short in length, but frequent in occurrence, taxi journeys. Building on this insight, we develop a smartphone application, OpenStreetCab, that offers a personalized consultation to mobile users on which taxi provider is cheaper for their journey. Almost five months after its launch, the app has attracted more than three thousand users in a single city. Their journey queries have provided additional insights on the potential savings similar technologies can have for urban commuters, with a highlight being that on average, a user in New York saves 6 U.S. Dollars per taxi journey if they pick the cheapest taxi provider. We run extensive experiments to show how Uber’s surge pricing is the driving factor of higher journey prices and therefore higher potential savings for our application’s users. Finally, motivated by the observation that Uber’s surge pricing is occurring more frequently that intuitively expected, we formulate a prediction task where the aim becomes to predict a geographic area’s tendency to surge. Using exogenous to Uber data, in particular Yellow Cab and Foursquare data, we show how it is possible to estimate customer demand within an area, and by extension surge pricing, with high accuracy.\",\n \"Title: Smart Sensing Systems for the Daily Drive.\\nYear: 2016\\n\\nAbstract: When driving, you might sometimes wonder, \\\"Are there any disruptions on my regular route that might delay me, and will I be able to find a parking space when I arrive?\\\" Two smartphone-based prototype systems can help answer these questions. The first is ParkSense, which can be used to sense on-street parking-space occupancy when coupled with electronic parking payment systems. The second system can sense and recognize a user's repeated car journeys, which can be used to provide personalized alerts to the user. Both systems aim to minimize the impact of sensing tasks on the device's lifetime so that the user can continue to use the device for its primary purpose. This department is part of a special issue on smart vehicle spaces.\",\n \"Title: The International Postal Network And Other Global Flows As Proxies For National Wellbeing\\nYear: 2016\\n\\nAbstract: The digital exhaust left by flows of physical and digital commodities provides a rich measure of the nature, strength and significance of relationships between countries in the global network. With this work, we examine how these traces and the network structure can reveal the socioeconomic profile of different countries. We take into account multiple international networks of physical and digital flows, including the previously unexplored international postal network. By measuring the position of each country in the Trade, Postal, Migration, International Flights, IP and Digital Communications networks, we are able to build proxies for a number of crucial socioeconomic indicators such as GDP per capita and the Human Development Index ranking along with twelve other indicators used as benchmarks of national well-being by the United Nations and other international organisations. In this context, we have also proposed and evaluated a global connectivity degree measure applying multiplex theory across the six networks that accounts for the strength of relationships between countries. We conclude by showing how countries with shared community membership over multiple networks have similar socioeconomic profiles. Combining multiple flow data sources can help understand the forces which drive economic activity on a global level. Such an ability to infer proxy indicators in a context of incomplete information is extremely timely in light of recent discussions on measurement of indicators relevant to the Sustainable Development Goals.\",\n \"Title: Integrating security and usability into the requirements and design process\\nYear: 2007\\n\\nAbstract: According to Ross Anderson, 'Many systems fail because their designers protect the wrong things or protect the right things in the wrong way'. Surveys also show that security incidents in industry are rising, which highlights the difficulty of designing good security. Some recent approaches have targeted security from the technological perspective, others from the human computer interaction angle, offering better User Interfaces (UIs) for improved usability of security mechanisms. However, usability issues also extend beyond the user interface and should be considered during system requirements and design. In this paper, we describe Appropriate and Effective Guidance for Information Security (AEGIS), a methodology for the development of secure and usable systems. AEGIS defines a development process and a UML meta-model of the definition and the reasoning over the system's assets. AEGIS has been applied to case studies in the area of Grid computing and we report on one of these.\",\n \"Title: Beyond location check-ins: Exploring physical and soft sensing to augment social check-in apps\\nYear: 2015\\n\\nAbstract: Smartphone sensing research has been advancing at a brisk pace. Yet, current social networking services often only take advantage of location sensing: applications like Foursquare use the phone's GPS and Wi-Fi radios to infer the user's location to simplify checking-in to a place. However, smartphone sensing could be exploited to considerably expand the spectrum of information a user can share with a few clicks with friends: not only the location of an event but activities such as “cooking dinner” or “waiting for a bus” can be predicted and suggested to the user to ease the check-in process. In this paper we show how mobile phone sensing can be used in this sense. For this prediction process to be accurate however, sensors need to be sampled often, with a considerable impact on the phone battery. To alleviate this issue, we explore streams of phone usage data (soft sensors), such as application usage, messages, and phone calls for predicting the user's activity in a more efficient fashion for augmenting mobile social check-in apps. We have deployed our application and collected a dataset of over 2700 check-ins to 48 activities from 20 users. Our analysis shows a prediction accuracy of 75% when offering 5 check-in suggestions to users. Furthermore, we show that when using only soft sensors we can achieve very similar performance to that obtained with real sensors, thereby significantly reducing the impact on the phone battery. This finding might have a potentially high impact on smartphone based activity check-in apps.\",\n \"Title: Studying human behavior at the intersection of mobile sensing and complex networks (Keynote abstract)\\nYear: 2016\\n\\nAbstract: Summary form only given. With the advent of powerful and inexpensive sensing technology the ability to study human behaviour and activity at large scale and for long periods is becoming a firm reality. Wearables and mobile devices further allow the continuous physical colocation with the users. This reality generates new challenges but also opens the door to potentially innovative ways of understanding our daily lives. In this talk we will discuss our experience in large mobile sensor deployments and in using complex network science for the analysis of mobile sensing data. We will discuss the issues raised by mobile sensing big data in terms of data crowdsourcing, continuous sensing challenges, data analysis, privacy, user feedback. Examples will be drawn from our healthcare, transport, urban planning and organization analytics studies.\",\n \"Title: Topological Properties and Temporal Dynamics of Place Networks in Urban Environments.\\nYear: 2015\\n\\nAbstract: Understanding the spatial networks formed by the trajectories of mobile users can be beneficial to applications ranging from epidemiology to local search. Despite the potential for impact in a number of fields, several aspects of human mobility networks remain largely unexplored due to the lack of large-scale data at a fine spatiotemporal resolution. Using a longitudinal dataset from the location-based service Foursquare, we perform an empirical analysis of the topological properties of place networks and note their resemblance to online social networks in terms of heavy-tailed degree distributions, triadic closure mechanisms and the small world property. Unlike social networks however, place networks present a mixture of connectivity trends in terms of assortativity that are surprisingly similar to those of the web graph. We take advantage of additional semantic information to interpret how nodes that take on functional roles such as `travel hub', or `food spot' behave in these networks. Finally, motivated by the large volume of new links appearing in place networks over time, we formulate the classic link prediction problem in this new domain. We propose a novel variant of gravity models that brings together three essential elements of inter-place connectivity in urban environments: network-level interactions, human mobility dynamics, and geographic distance. We evaluate this model and find it outperforms a number of baseline predictors and supervised learning algorithms on a task of predicting new links in a sample of one hundred popular cities.\",\n \"Title: Measuring Urban Social Diversity Using Interconnected Geo-Social Networks.\\nYear: 2016\\n\\nAbstract: Large metropolitan cities bring together diverse individuals, creating opportunities for cultural and intellectual exchanges, which can ultimately lead to social and economic enrichment. In this work, we present a novel network perspective on the interconnected nature of people and places, allowing us to capture the social diversity of urban locations through the social network and mobility patterns of their visitors. We use a dataset of approximately 37K users and 42K venues in London to build a network of Foursquare places and the parallel Twitter social network of visitors through check-ins. We define four metrics of the social diversity of places which relate to their social brokerage role, their entropy, the homogeneity of their visitors and the amount of serendipitous encounters they are able to induce. This allows us to distinguish between places that bring together strangers versus those which tend to bring together friends, as well as places that attract diverse individuals as opposed to those which attract regulars. We correlate these properties with wellbeing indicators for London neighbourhoods and discover signals of gentrification in deprived areas with high entropy and brokerage, where an influx of more affluent and diverse visitors points to an overall improvement of their rank according to the UK Index of Multiple Deprivation for the area over the five-year census period. Our analysis sheds light on the relationship between the prosperity of people and places, distinguishing between different categories and urban geographies of consequence to the development of urban policy and the next generation of socially-aware location-based applications.\",\n \"Title: Smart phone based systems for social psychological research: challenges and design guidelines\\nYear: 2011\\n\\nAbstract: Social psychology research deals with understanding many aspects of human behavior, and this helps not only to gain insights into this complex phenomenon but also to provide useful feedback to the participants. Social psychological research is mainly conducted through self-reports and surveys, however, this methodology is laborious and requires considerable offline analysis. Moreover, self-reports are also found to be biased towards pleasant experiences. Mobile phones represent a perfect platform for conducting social psychological research as they are ubiquitous, unobtrusive, and sensor-rich devices. However, limited battery and computing power, and expensive data plans make it difficult to support various demanding sensing and computation requirements of the social psychological research. In this paper, we describe the specific challenges in building systems based on off-the-shelf mobile phones for conducting social experiments, and provide design guidelines based on our recent works for implementing such systems.\",\n \"Title: Monitoring A Large Construction Site Using Wireless Sensor Networks\\nYear: 2015\\n\\nAbstract: Despite the significant advances made by wireless sensor network research, deployments of such networks in real application environments are fraught with significant difficulties and challenges that include robust topology design, network diagnostics and maintenance. Based on our experience of a six-month-long wireless sensor network deployment in a large construction site, we highlight these challenges and argue the need for new tools and enhancements to current protocols to address these challenges.\",\n \"Title: ZOE: A Cloud-less Dialog-enabled Continuous Sensing Wearable Exploiting Heterogeneous Computation\\nYear: 2015\\n\\nAbstract: The wearable revolution, as a mass-market phenomenon, has finally arrived. As a result, the question of how wearables should evolve over the next 5 to 10 years is assuming an increasing level of societal and commercial importance. A range of open design and system questions are emerging, for instance: How can wearables shift from being largely health and fitness focused to tracking a wider range of life events? What will become the dominant methods through which users interact with wearables and consume the data collected? Are wearables destined to be cloud and/or smartphone dependent for their operation? Towards building the critical mass of understanding and experience necessary to tackle such questions, we have designed and implemented ZOE - a match-box sized (49g) collar- or lapel-worn sensor that pushes the boundary of wearables in an important set of new directions. First, ZOE aims to perform multiple deep sensor inferences that span key aspects of everyday life (viz. personal, social and place information) on continuously sensed data; while also offering this data not only within conventional analytics but also through a speech dialog system that is able to answer impromptu casual questions from users. (Am I more stressed this week than normal?) Crucially, and unlike other rich-sensing or dialog supporting wearables, ZOE achieves this without cloud or smartphone support - this has important side-effects for privacy since all user information can remain on the device. Second, ZOE incorporates the latest innovations in system-on-a-chip technology together with a custom daughter-board to realize a three-tier low-power processor hierarchy. We pair this hardware design with software techniques that manage system latency while still allowing ZOE to remain energy efficient (with a typical lifespan of 30 hours), despite its high sensing workload, small form-factor, and need to remain responsive to user dialog requests.\",\n \"Title: Developing and Deploying Mobile Sensing Applications in the Wild\\nYear: 2016\\n\\nAbstract: Summary form only given. With the advent of powerful and inexpensive sensing technology the ability to study human behaviour and activity at large scale and for long periods is becoming a firm reality. Wearables and mobile devices further allow the continuous physical colocation with the users. This reality generates new challenges but also opens the door to potentially innovative ways of understanding our daily lives. In this talk we will discuss our experience in large mobile sensor deployments. We will discuss the issues raised by mobile sensing big data in terms of data crowdsourcing, continuous sensing challenges, data analysis, privacy, user feedback. Examples will be drawn from our healthcare, transport, urban planning and organization analytics studies.\",\n \"Title: Towards multimodal deep learning for activity recognition on mobile devices.\\nYear: 2016\\n\\nAbstract: Current smartphones and smartwatches come equipped with a variety of sensors, from light sensor and inertial sensors to radio interfaces, enabling applications running on these devices to make sense of their surrounding environment. Rather than using sensors independently, combining their sensing capabilities facilitates more interesting and complex applications to emerge (e.g., user activity recognition). But differences between sensors ranging from sampling rate to data generation model (event triggered or continuous sampling) make integration of sensor streams challenging. Here we investigate the opportunity to use deep learning to perform this integration of sensor data from multiple sensors. The intuition is that neural networks can identify nonintuitive features largely from cross-sensor correlations which can result in a more accurate estimation. Initial results with a variant of a Restricted Boltzmann Machine (RBM), show better performance with this new approach compared to classic solutions.\",\n \"Title: LEO: scheduling sensor inference algorithms across heterogeneous mobile processors and network resources.\\nYear: 2016\\n\\nAbstract: Mobile apps that use sensors to monitor user behavior often employ resource heavy inference algorithms that make computational offloading a common practice. However, existing schedulers/offloaders typically emphasize one primary offloading aspect without fully exploring complementary goals (e.g., heterogeneous resource management with only partial visibility into underlying algorithms, or concurrent sensor app execution on a single resource) and as a result, may overlook performance benefits pertinent to sensor processing. We bring together key ideas scattered in existing offloading solutions to build LEO -- a scheduler designed to maximize the performance for the unique workload of continuous and intermittent mobile sensor apps without changing their inference accuracy. LEO makes use of domain specific signal processing knowledge to smartly distribute the sensor processing tasks across the broader range of heterogeneous computational resources of high-end phones (CPU, co-processor, GPU and the cloud). To exploit short-lived, but substantial optimization opportunities, and remain responsive to the needs of near real-time apps such as voice-based natural user interfaces, LEO runs as a service on a low-power co-processor unit (LPU) to perform both frequent and joint schedule optimization for concurrent pipelines. Depending on the workload and network conditions, LEO is between 1.6 and 3 times more energy efficient than conventional cloud offloading with CPU-bound sensor sampling. In addition, even if a general-purpose scheduler is optimized directly to leverage an LPU, we find LEO still uses only a fraction (< 1/7) of the energy overhead for scheduling and is up to 19% more energy efficient for medium to heavy workloads.\",\n \"Title: Bridge structural monitoring through a vibration energy harvesting wireless sensor network: Poster Abstract.\\nYear: 2016\\n\\nAbstract: Structural monitoring applications such as corrosion assessment, measurement of concrete temperature or moisture content of critical bridge structures can greatly benefit from the use of wireless sensor networks (WSNs), however energy harvesting for the operation of the network remains a challenge in this setting. We present a multihop vibration-based energy harvesting WSN system for bridge monitoring applications. Our preliminary simulation experiments show that the system is able to maintain energy neutral operation over time, preserving energy with careful management of sleep and communication times.\",\n \"Title: Developing and Deploying a Taxi Price Comparison Mobile App in the Wild: Insights and Challenges.\\nYear: 2018\\n\\nAbstract: As modern transportation systems become more complex, there is need for mobile applications that allow travelers to navigate efficiently in cities. In taxi transport the recent proliferation of Uber has introduced new norms including a flexible pricing scheme where journey costs can change rapidly depending on passenger demand and driver supply. To make informed choices on the most appropriate provider for their journeys, travelers need access to knowledge about provider pricing in real time. To this end, we developed OpenStreetCab a mobile application that offers advice on taxi transport comparing provider prices. We describe its development and deployment in two cities, London and New York, and analyse thousands of user journey queries to compare the price patterns of Uber against major local taxi providers. We have observed large heterogeneity across the taxi transport markets in the two cities. This motivated us to perform a price validation and measurement experiment on the ground comparing Uber and Black Cabs in London. The experimental results reveal interesting insights: not only they confirm feedback on pricing and service quality received by professional driver users, but also they reveal the tradeoffs between prices and journey times between taxi providers. With respect to journey times in particular, we show how experienced taxi drivers, in the majority of the cases, are able to navigate faster to a destination compared to drivers who rely on modern navigation systems. We provide evidence that this advantage becomes stronger in the centre of a city where urban density is high.\",\n \"Title: Detecting Socio-Economic Impact of Cultural Investment Through Geo-Social Network Analysis.\\nYear: 2018\\n\\nAbstract: © Copyright 2017, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Taking advantage of nearly 4 million transition records for three years in London from a popular location-based social network service, Foursquare, we study how to track the impact and measure the effectiveness of cultural investment in small urban areas. We reveal the underlying relationships between socio-economic status, local cultural expenditure, and network features extracted from user mobility trajectories. This research presents how geo-social and mobile services more generally can be used as a proxy to track local changes as government financial effort is put in developing urban areas, and thus gives evidence and suggestions for further policy-making and investment optimization.\",\n \"Title: Mobile Sensing at the Service of Mental Well-being: a Large-scale Longitudinal Study.\\nYear: 2017\\n\\nAbstract: Measuring mental well-being with mobile sensing has been an increasingly active research topic. Pervasiveness of smartphones combined with the convenience of mobile app distribution platforms (e.g., Google Play) provide a tremendous opportunity to reach out to millions of users. However, the studies at the confluence of mental health and mobile sensing have been longitudinally limited, controlled, or confined to a small number of participants. In this paper we report on what we believe is the largest longitudinal in-the-wild study of mood through smartphones. We describe an Android app to collect participants' self-reported moods and system triggered experience sampling data while passively measuring their physical activity, sociability, and mobility via their device's sensors. We report the results of a large-scale analysis of the data collected for about three years from 18,000 users. The paper makes three primary contributions. First, we show how we used physical and software sensors in smartphones to automatically and accurately identify routines. Then, we demonstrate the strong correlation between these routines and users' personality, well-being perception, and other psychological variables. Finally, we explore predictability of users' mood using their passive sensing data. Our findings show that, especially for weekends, mobile sensing can be used to predict users' mood with an accuracy of about 70%. These results have the potential to impact the design of future mobile apps for mood/behavior tracking and interventions.\",\n \"Title: Accelerating Mobile Audio Sensing Algorithms through On-Chip GPU Offloading.\\nYear: 2017\\n\\nAbstract: GPUs have recently enjoyed increased popularity as general purpose software accelerators in multiple application domains including computer vision and natural language processing. However, there has been little exploration into the performance and energy trade-offs mobile GPUs can deliver for the increasingly popular workload of deep-inference audio sensing tasks, such as, spoken keyword spotting in energy-constrained smartphones and wearables. In this paper, we study these trade-offs and introduce an optimization engine that leverages a series of structural and memory access optimization techniques that allow audio algorithm performance to be automatically tuned as a function of GPU device specifications and model semantics. We find that parameter optimized audio routines obtain inferences an order of magnitude faster than sequential CPU implementations, and up to 6.5x times faster than cloud offloading with good connectivity, while critically consuming 3-4x less energy than the CPU. Under our optimized GPU, conventional wisdom about how to use the cloud and low power chips is broken. Unless the network has a throughput of at least 20Mbps (and a RTT of 25 ms or less), with only about 10 to 20 seconds of buffering audio data for batched execution, the optimized GPU audio sensing apps begin to consume less energy than cloud offloading. Under such conditions we find the optimized GPU can provide energy benefits comparable to low-power reference DSP implementations with some preliminary level of optimization; in addition to the GPU always winning with lower latency.\",\n \"Title: Using human raters to characterize the psychological characteristics of GPS-based places.\\nYear: 2017\\n\\nAbstract: This paper showcases an approach to combining smart-phone sensing technology, web mapping services, and psychological assessments to enhance our understanding of the psychological characteristics of places. For two weeks, twenty-six students used a smartphone app that passively collected GPS sensor data. Human raters then characterized their most frequently visited places on a number of psychological characteristics, such as ambience (e.g. how safe, urban, lively a place was perceived) and personality (e.g. a place's perceived extroversion and conscientiousness). We explored the relationship between these place characteristics and participants own personality traits, showing how the personality traits of the average visitor to a location can be similar or different from the place's characteristics. We conclude with a discussion of how this approach can be used in future research on places.\",\n \"Title: Understanding the Role of Places and Activities on Mobile Phone Interaction and Usage Patterns.\\nYear: 2017\\n\\nAbstract: User interaction patterns with mobile apps and notifications are generally complex due to the many factors involved. However a deep understanding of what influences them can lead to more acceptable applications that are able to deliver information at the right time. In this paper, we present for the first time an in-depth analysis of interaction behavior with notifications in relation to the location and activity of users. We conducted an in-situ study for a period of two weeks to collect more than 36,000 notifications, 17,000 instances of application usage, 77,000 location samples, and 487 days of daily activity entries from 26 students at a UK university.\\n\\nOur results show that users’ attention towards new notifications and willingness to accept them are strongly linked to the location they are in and in minor part to their current activity. We consider both users’ receptivity and attentiveness, and we show that different response behaviors are associated to different locations. These findings are fundamental from a design perspective since they allow us to understand how certain types of places are linked to specific types of interaction behavior. This information can be used as a basis for the development of novel intelligent mobile applications and services.\",\n \"Title: Detecting Emerging Activity-Based Working Traits through Wearable Technology.\\nYear: 2017\\n\\nAbstract: A recent trend in corporate real-estate is Activity-Based Working (ABW). The ABW concept removes designated desks but offers different work settings designed to support typical work activities. In this context there is still a need for objective data to understand the implications of these design decisions. We aim to contribute by using automated data collection to study how ABW’s principles impact office usage and dynamics.\\n\\nTo this aim we analyse team dynamics and employees’ tie strength in relation to space usage and organisational hierarchy using data collected with wearable devices in a company adopting ABW principles. Our findings show that the office fosters interactions across team boundaries and among the lower levels of the hierarchy suggesting a strong lateral communication. Employees also tend to have low space exploration on a daily basis which is instead more prevalent during an average week and strong social clusters seem to be resisting the ABW principles of space dynamics. With the availability of two additional data sets about social encounters in traditional offices we highlight traits emerging from the application of ABW’s principles. In particular, we observe how the absence of designated desks might be responsible for more rapid dynamics inside the office.\\n\\nIn more general terms, this work opens the door to new and scalable technology-based methodologies to study dynamic office usage and social interactions.\",\n \"Title: Multimodal Deep Learning for Activity and Context Recognition.\\nYear: 2017\\n\\nAbstract: Wearables and mobile devices see the world through the lens of half a dozen low-power sensors, such as, barometers, accelerometers, microphones and proximity detectors. But differences between sensors ranging from sampling rates, discrete and continuous data or even the data type itself make principled approaches to integrating these streams challenging. How, for example, is barometric pressure best combined with an audio sample to infer if a user is in a car, plane or bike? Critically for applications, how successfully sensor devices are able to maximize the information contained across these multi-modal sensor streams often dictates the fidelity at which they can track user behaviors and context changes. This paper studies the benefits of adopting deep learning algorithms for interpreting user activity and context as captured by multi-sensor systems. Specifically, we focus on four variations of deep neural networks that are based either on fully-connected Deep Neural Networks (DNNs) or Convolutional Neural Networks (CNNs). Two of these architectures follow conventional deep models by performing feature representation learning from a concatenation of sensor types. This classic approach is contrasted with a promising deep model variant characterized by modality-specific partitions of the architecture to maximize intra-modality learning. Our exploration represents the first time these architectures have been evaluated for multimodal deep learning under wearable data -- and for convolutional layers within this architecture, it represents a novel architecture entirely. Experiments show these generic multimodal neural network models compete well with a rich variety of conventional hand-designed shallow methods (including feature extraction and classifier construction) and task-specific modeling pipelines, across a wide-range of sensor types and inference tasks (four different datasets). Although the training and inference overhead of these multimodal deep approaches is in some cases appreciable, we also demonstrate the feasibility of on-device mobile and wearable execution is not a barrier to adoption. This study is carefully constructed to focus on multimodal aspects of wearable data modeling for deep learning by providing a wide range of empirical observations, which we expect to have considerable value in the community. We summarize our observations into a series of practitioner rules-of-thumb and lessons learned that can guide the usage of multimodal deep learning for activity and context detection.\",\n \"Title: You Are Sensing, but Are You Biased?: A User Unaided Sensor Calibration Approach for Mobile Sensing\\nYear: 2018\\n\\nAbstract: Mobile devices are becoming pervasive to our daily lives: they follow us everywhere and we use them for much more than just communication. These devices are also equipped with a myriad of different sensors that have the potential to allow the tracking of human activities, user patterns, location, direction and much more. Following this direction, many movements including sports, quantified self, and mobile health ones are starting to heavily rely on this technology, making it pivotal that the sensors offer high accuracy.\\n\\nHowever, heterogeneity in hardware manufacturing, slight substrate differences, electronic interference as well as external disturbances are just few of the reasons that limit sensor output accuracy which in turn hinders sensor usage in applications which need very high granularity and precision, such as quantified-self applications. Although, calibration of sensors is a widely studied topic in literature to the best of our knowledge no publicly available research exists that specifically tackles the calibration of mobile phones and existing methods that can be adapted for use in mobile devices not only require user interaction but they are also not adaptive to changes. Additionally, alternative approaches for performing more granular and accurate sensing exploit body-wide sensor networks using mobile phones and additional sensors; as one can imagine these techniques can be bulky, tedious, and not particularly user friendly. Moreover, existing techniques for performing data corrections post-acquisition can produce inconsistent results as they miss important context information provided from the device itself; which when used, has been shown to produce better results without a imposing a significant power-penalty.\\n\\nIn this paper we introduce a novel multiposition calibration scheme that is specifically targeted at mobile devices Our scheme exploits machine learning techniques to perform an adaptive, power-efficient auto-calibration procedure with which achieves high output sensor accuracy when compared to state of the art techniques without requiring any user interaction or special equipment beyond device itself Moreover, the energy costs associated with our approach are lower than the alternatives (such as Kalman filter based solutions) and the overall power penalty is < 5% when compared against power usage that is exhibited when using uncalibrated traces, thus, enabling our technique to be used efficiently on a wide variety of devices Finally, our evaluation illustrates that calibrated signals offer a tangible benefit in classification accuracy, ranging from 3 to 10%, over uncalibrated ones when using state of the art classifiers, on the other hand when using simpler SVM classifiers the classification improvement is boosted ranging from 8% to 12% making lower performing classifiers much more reliable Additionally, we show that for similar activities which are hard to distinguish otherwise, we reach an accuracy of > 95% when using neural network classifiers and > 88% when using SVM classifiers where uncalibrated data classification only reaches ~ 85% and ~ 80% respectively This can be a make or break factor in the use of accelerometer and gyroscope data in applications requiring high accuracy e g sports, health, games and others\",\n \"Title: Surveying Areas in Developing Regions Through Context Aware Drone Mobility.\\nYear: 2018\\n\\nAbstract: Developing regions are often characterized by large areas that are poorly reachable or explored. The mapping of these regions and the census of roaming populations in these areas are often difficult and sporadic.\\n\\nIn this paper we put forward an approach to aid area surveying which relies on autonomous drone mobility. In particular we illustrate the two main components of the approach. An efficient on-device object detection component, built on Convolutional Neural Networks, capable of detecting human settlements and animals on the ground with acceptable performance (latency and accuracy) and a path planning component, informed by the object identification module, which exploits Artificial Potential Fields to dynamically adapt the flight in order to gather useful information of the environment, while keeping optimal flight paths. We report some initial performance results of the on board visual perception module and describe our experimental platform based on a fixed-wing aircraft.\",\n \"Title: Quantifying Privacy Loss of Human Mobility Graph Topology.\\nYear: 2018\\n\\nAbstract: network, or graph, with nodes representing places of significance which an individual visits, such as their home, work, places of social amenity, etc., and edge weights corresponding to probability estimates of movements between these places. Previous research has shown that individuals can be identified by a small number of geolocated nodes in their mobility network, rendering mobility trace anonymization a hard task. In this paper we build on prior work and demonstrate that even when all location and timestamp information is removed from nodes, the graph topology of an individual mobility network itself is often uniquely identifying. Further, we observe that a mobility network is often unique, even when only a small number of the most popular nodes and edges are considered. We evaluate our approach using a large dataset of cell-tower location traces from 1 500 smartphone handsets with a mean duration of 430 days. We process the data to derive the top−N places visited by the device in the trace, and find that 93% of traces have a unique top−10 mobility network, and all traces are unique when considering top−15 mobility networks. Since mobility patterns, and therefore mobility networks for an individual, vary over time, we use graph kernel distance functions, to determine whether two mobility networks, taken at different points in time, represent the same individual. We then show that our distance metrics, while imperfect predictors, perform significantly better than a random strategy and therefore our approach represents a significant loss in privacy.\",\n \"Title: Learning from Our Mistakes: Identifying Opportunities for Technology Intervention against Everyday Cognitive Failure.\\nYear: 2018\\n\\nAbstract: There is growing opportunity for technologies to augment human memory and other cognitive processes, but systems to date typically either address known cognitive impairments such as autism and Alzheimers disease or look to enhance ones general capacity for a specific task. In contrast to these approaches, we argue that recognition and quantification of human error is key to the design of future co...\",\n \"Title: Discovering Latent Patterns of Urban Cultural Interactions in WeChat for Modern City Planning.\\nYear: 2018\\n\\nAbstract: Cultural activity is an inherent aspect of urban life and the success of a modern city is largely determined by its capacity to offer generous cultural entertainment to its citizens. To this end, the optimal allocation of cultural establishments and related resources across urban regions becomes of vital importance, as it can reduce financial costs in terms of planning and improve quality of life in the city, more generally. In this paper, we make use of a large longitudinal dataset of user location check-ins from the online social network WeChat to develop a data-driven framework for cultural planning in the city of Beijing. We exploit rich spatio-temporal representations on user activity at cultural venues and use a novel extended version of the traditional latent Dirichlet allocation model that incorporates temporal information to identify latent patterns of urban cultural interactions. Using the characteristic typologies of mobile user cultural activities emitted by the model, we determine the levels of demand for different types of cultural resources across urban areas. We then compare those with the corresponding levels of supply as driven by the presence and spatial reach of cultural venues in local areas to obtain high resolution maps that indicate urban regions with lack of cultural resources, and thus give suggestions for further urban cultural planning and investment optimisation.\",\n \"Title: Predicting the Spatio-Temporal Evolution of Chronic Diseases in Population with Human Mobility Data.\\nYear: 2018\\n\\nAbstract: © 2018 International Joint Conferences on Artificial Intelligence. All right reserved. Chronic diseases like cancer and diabetes are major threats to human life. Understanding the distribution and progression of chronic diseases of a population is important in assisting the allocation of medical resources as well as the design of policies in preemptive healthcare. Traditional methods to obtain large scale indicators on population health, e.g., surveys and statistical analysis, can be costly and time-consuming and often lead to a coarse spatio-temporal picture. In this paper, we leverage a dataset describing the human mobility patterns of citizens in a large metropolitan area. By viewing local human lifestyles we predict the evolution rate of several chronic diseases at the level of a city neighborhood. We apply the combination of a collaborative topic modeling (CTM) and a Gaussian mixture method (GMM) to tackle the data sparsity challenge and achieve robust predictions on health conditions simultaneously. Our method enables the analysis and prediction of disease rate evolution at fine spatio-temporal scales and demonstrates the potential of incorporating datasets from mobile web sources to improve population health monitoring. Evaluations using real-world check-in and chronic disease morbidity datasets in the city of London show that the proposed CTM+GMM model outperforms various baseline methods.\",\n \"Title: Evaluating the impact of the 2012 Olympic Games policy on the regeneration of East London using spatio-temporal big data.\\nYear: 2018\\n\\nAbstract: For urban governments, introducing policies has long been adopted as a main approach to instigate regeneration processes, and to promote social mixing and vitality within the city. However, due to the absence of large fine-grained datasets, the effects of these policies have been historically hard to evaluate. In this research, we illustrate how a combination of large-scale datasets, the Index of Deprivation and Foursquare data (an online geo-social network service) could be used to investigate the impact of the 2012 Olympic Games on the regeneration of East London neighbourhoods. We study and quantify both the physical and socio-economic aspects of this, where our empirical findings suggest that the target areas did indeed undergo regeneration after the Olympic project in some ways. In general, the growth rate of Foursquare venue density in Olympic host boroughs is higher than the cityu0027s average level since the preparation period of the Games and up to two years after the event. Furthermore, the deprivation levels in East London boroughs also saw improvements in various aspects after the Olympic Games. One negative outcome we notice is that the housing affordability becomes even more of an issue in East London areas with the regeneration gradually unfolding.\",\n \"Title: Cultural Investment and Urban Socio-Economic Development: A Geo-Social Network Approach.\\nYear: 2018\\n\\nAbstract: Being able to assess the impact of government-led investment onto socio-economic indicators in cities has long been an important target of urban planning. However, owing to the lack of large-scale data with a fine spatio-temporal resolution, there have been limitations in terms of how planners can track the impact and measure the effectiveness of cultural investment in small urban areas. Taking advantage of nearly 4 million transition records for 3 years in London from a popular location-based social network service, Foursquare, we study how the socio-economic impact of government cultural expenditure can be detected and predicted. Our analysis shows that network indicators such as average clustering coefficient or centrality can be exploited to estimate the likelihood of local growth in response to cultural investment. We subsequently integrate these features in supervised learning models to infer socio-economic deprivation changes for London's neighbourhoods. This research presents how geosocial and mobile services can be used as a proxy to track and predict socio-economic deprivation changes as government financial effort is put in developing urban areas and thus gives evidence and suggestions for further policymaking and investment optimization.\",\n \"Title: The Specter of Malicious Computing: Securing the Internet of Things.\\nYear: 2018\\n\\nAbstract: The Internet of Things (IoT) is taking off, and with it the vision of pervasive computing. Internet-enabled computers are now embedded in everything from cars to pacemakers to electronic door locks to home heating controllers. Unfortunately, security, safety, and privacy considerations have lagged behind in the race to build new applications and services. Researchers demonstrated years ago how to ...\",\n \"Title: What Will You Do for the Rest of the Day?: An Approach to Continuous Trajectory Prediction.\\nYear: 2018\\n\\nAbstract: Understanding and predicting human mobility is vital to a large number of applications, ranging from recommendations to safety and urban service planning. In some travel applications, the ability to accurately predict the user's future trajectory is vital for delivering high quality of service. The accurate prediction of detailed trajectories would empower location-based service providers with the ability to deliver more precise recommendations to users. Existing work on human mobility prediction has mainly focused on the prediction of the next location (or the set of locations) visited by the user, rather than on the prediction of the continuous trajectory (sequences of further locations and the corresponding arrival and departure times). Furthermore, existing approaches often return predicted locations as regions with coarse granularity rather than geographical coordinates, which limits the practicality of the prediction.\\n\\nIn this paper, we introduce a novel trajectory prediction problem: given historical data and a user's initial trajectory in the morning, can we predict the user's full trajectory later in the day (e.g. the afternoon trajectory)? The predicted continuous trajectory includes the sequence of future locations, the stay times, and the departure times. We first conduct a comprehensive analysis about the relationship between morning trajectories and the corresponding afternoon trajectories, and found there is a positive correlation between them. Our proposed method combines similarity metrics over the extracted temporal sequences of locations to estimate similar informative segments across user trajectories.\\n\\nOur evaluation shows results on both labeled and geographical trajectories with a prediction error reduced by 10-35% in comparison to the baselines. This improvement has the potential to enable precise location services, raising usefulness to users to unprecedented levels. We also present empirical evaluations with Markov model and Long Short Term Memory (LSTM), a state-of-the-art Recurrent Neural Network model. Our proposed method is shown to be more effective when smaller number of samples are used and is exponentially more efficient than LSTM.\",\n \"Title: Keep Your Friends Close and Your Facebook Friends Closer: A Multiplex Network Approach to the Analysis of Offline and Online Social Ties.\\nYear: 2014\\n\\nAbstract: Social media allow for an unprecedented amount of interaction between people online. A fundamental aspect of human social behavior, however, is the tendency of people to associate themselves with like-minded individuals, forming homogeneous social circles both online and offline. In this work, we apply a new model that allows us to distinguish between social ties of varying strength, and to observe evidence of homophily with regards to politics, music, health, residential sector & year in college, within the online and offline social network of 74 college students. We present a multiplex network approach to social tie strength, here applied to mobile communication data - calls, text messages, and co-location, allowing us to dimensionally identify relationships by considering the number of communication channels utilized between students. We find that strong social ties are characterized by maximal use of communication channels, while weak ties by minimal use. We are able to identify 75% of close friendships, 90% of weaker ties, and 90% of Facebook friendships as compared to reported ground truth. We then show that stronger ties exhibit greater profile similarity than weaker ones. Apart from high homogeneity in social circles with respect to political and health aspects, we observe strong homophily driven by music, residential sector and year in college. Despite Facebook friendship being highly dependent on residence and year, exposure to less homogeneous content can be found in the online rather than the offline social circles of students, most notably in political and music aspects.\",\n \"Title: Predicting the temporal activity patterns of new venues.\\nYear: 2018\\n\\nAbstract: Estimating revenue and business demand of a newly opened venue is paramount as these early stages often involve critical decisions such as first rounds of staffing and resource allocation. Traditionally, this estimation has been performed through coarse-grained measures such as observing numbers in local venues or venues at similar places (e.g., coffee shops around another station in the same city). The advent of crowdsourced data from devices and services carried by individuals on a daily basis has opened up the possibility of performing better predictions of temporal visitation patterns for locations and venues. In this paper, using mobility data from Foursquare, a location-centric platform, we treat venue categories as proxies for urban activities and analyze how they become popular over time. The main contribution of this work is a prediction framework able to use characteristic temporal signatures of places together with k-nearest neighbor metrics capturing similarities among urban regions, to forecast weekly popularity dynamics of a new venue establishment in a city neighborhood. We further show how we are able to forecast the popularity of the new venue after one month following its opening by using locality and temporal similarity as features. For the evaluation of our approach we focus on London. We show that temporally similar areas of the city can be successfully used as inputs of predictions of the visit patterns of new venues, with an improvement of 41% compared to a random selection of wards as a training set for the prediction task. We apply these concepts of temporally similar areas and locality to the real-time predictions related to new venues and show that these features can effectively be used to predict the future trends of a venue. Our findings have the potential to impact the design of location-based technologies and decisions made by new business owners.\",\n \"Title: Understanding the Effects of the Neighbourhood Built Environment on Public Health with Open Data\\nYear: 2019\\n\\nAbstract: The investigation of the effect of the built environment in a neighbourhood and how it impacts residents' health is of value to researchers from public health policy to social science. The traditional methods to assess this impact is through surveys which lead to temporally and spatially coarse grained data and are often not cost effective. Here we propose an approach to link the effects of neighbourhood services over citizen health using a technique that attempts to highlight the cause-effect aspects of these relationships. The method is based on the theory of propensity score matching with multiple 'doses' and it leverages existing fine grained open web data. To demonstrate the method, we study the effect of sport venue presence on the prevalence of antidepressant prescriptions in over 600 neighbourhoods in London over a period of three years. We find the distribution of effects is approximately normal, centred on a small negative effect on prescriptions with increases in the availability of sporting facilities, on average. We assess the procedure through some standard quantitative metrics as well as matching on synthetic data generated by modelling the real data. This approach opens the door to fast and inexpensive alternatives to quantify and continuously monitor effects of the neighborhood built environment on population health.\",\n \"Title: Passive mobile sensing and psychological traits for large scale mood prediction\\nYear: 2019\\n\\nAbstract: Experience sampling has long been the established method to sample people's mood in order to assess their mental state. Smartphones start to be used as experience sampling tools for mental health state as they accompany individuals during their day and can therefore gather in-the-moment data. However, the granularity of the data needs to be traded off with the level of interruption these tools introduce. As a consequence the data collected with this technique is often sparse. This has been obviated by the use of passive sensing in addition to mood reports, however, this adds additional noise.\\n\\nIn this paper we show that psychological traits collected through one-off questionnaires combined with passively collected sensing data (movement from the accelerometer and noise levels from the microphone) can be used to detect individuals whose general mood deviates from the common relaxed characteristic of the general population. By using the reported mood as a classification target we show how to design models that depend only on passive sensors and one-off questionnaires, without bothering users with tedious experience sampling. We validate our approach by using a large dataset of mood reports and passive sensing data collected in the wild with tens of thousands of participants, finding that the combination of these modalities achieves the best classification performance, and that passive sensing yields a +5% boost in accuracy. We also show that sensor data collected for a week performs better than single days for this task. We discuss feature extraction techniques and appropriate classifiers for this kind of multimodal data, as well as overfitting shortcomings of using deep learning to handle static and dynamic features. We believe these findings have significant implications for mobile health applications that can benefit from the correct modeling of passive sensing along with extra user metadata.\",\n \"Title: Topic-Enhanced Memory Networks for Personalised Point-of-Interest Recommendation.\\nYear: 2019\\n\\nAbstract: Point-of-Interest (POI) recommender systems play a vital role in people's lives by recommending unexplored POIs to users and have drawn extensive attention from both academia and industry. Despite their value, however, they still suffer from the challenges of capturing complicated user preferences and fine-grained user-POI relationship for spatio-temporal sensitive POI recommendation. Existing recommendation algorithms, including both shallow and deep approaches, usually embed the visiting records of a user into a single latent vector to model user preferences: this has limited power of representation and interpretability. In this paper, we propose a novel topic-enhanced memory network (TEMN), a deep architecture to integrate the topic model and memory network capitalising on the strengths of both the global structure of latent patterns and local neighbourhood-based features in a nonlinear fashion. We further incorporate a geographical module to exploit user-specific spatial preference and POI-specific spatial influence to enhance recommendations. The proposed unified hybrid model is widely applicable to various POI recommendation scenarios. Extensive experiments on real-world WeChat datasets demonstrate its effectiveness (improvement ratio of 3.25% and 29.95% for context-aware and sequential recommendation, respectively). Also, qualitative analysis of the attention weights and topic modeling provides insight into the model's recommendation process and results.\",\n \"Title: Sequence Multi-task Learning to Forecast Mental Wellbeing from Sparse Self-reported Data\\nYear: 2019\\n\\nAbstract: Smartphones have started to be used as self reporting tools for mental health state as they accompany individuals during their days and can therefore gather temporally fine grained data. However, the analysis of self reported mood data offers challenges related to non-homogeneity of mood assessment among individuals due to the complexity of the feeling and the reporting scales, as well as the noise and sparseness of the reports when collected in the wild. In this paper, we propose a new end-to-end ML model inspired by video frame prediction and machine translation, that forecasts future sequences of mood from previous self-reported moods collected in the real world using mobile devices. Contrary to traditional time series forecasting algorithms, our multi-task encoder-decoder recurrent neural network learns patterns from different users, allowing and improving the prediction for users with limited number of self-reports. Unlike traditional feature-based machine learning algorithms, the encoder-decoder architecture enables to forecast a sequence of future moods rather than one single step. Meanwhile, multi-task learning exploits some unique characteristics of the data (mood is bi-dimensional), achieving better results than when training single-task networks or other classifiers.\\n\\nOur experiments using a real-world dataset of 33,000 user-weeks revealed that (i) 3 weeks of sparsely reported mood is the optimal number to accurately forecast mood, (ii) multi-task learning models both dimensions of mood \\\"valence and arousal\\\" with higher accuracy than separate or traditional ML models, and (iii) mood variability, personality traits and day of the week play a key role in the performance of our model. We believe this work provides psychologists and developers of future mobile mental health applications with a ready-to-use and effective tool for early diagnosis of mental health issues at scale.\",\n \"Title: Segmentation-free Heart Pathology Detection Using Deep Learning\\nYear: 2021\\n\\nAbstract: Cardiovascular (CV) diseases are the leading cause of death in the world, and auscultation is typically an essential part of a cardiovascular examination. The ability to diagnose a patient based on their heart sounds is a rather difficult skill to master. Thus, many approaches for automated heart auscultation have been explored. However, most of the previously proposed methods involve a segmentation step, the performance of which drops significantly for high pulse rates or noisy signals. In this work, we propose a novel segmentation-free heart sound classification method. Specifically, we apply discrete wavelet transform to denoise the signal, followed by feature extraction and feature reduction. Then, Support Vector Machines and Deep Neural Networks are utilised for classification. On the PASCAL heart sound dataset our approach showed superior performance compared to others, achieving 81% and 96% precision on normal and murmur classes, respectively. In addition, for the first time, the data were further explored under a user-independent setting, where the proposed method achieved 92% and 86% precision on normal and murmur, demonstrating the potential of enabling automatic murmur detection for practical use.\",\n \"Title: Earables for Detection of Bruxism: a Feasibility Study\\nYear: 2021\\n\\nAbstract: ABSTRACTBruxism is a disorder characterised by teeth grinding and clenching, and many bruxism sufferers are not aware of this disorder until their dental health professional notices permanent teeth wear. Stress and anxiety are often listed among contributing factors impacting bruxism exacerbation, which may explain why the COVID-19 pandemic gave rise to a bruxism epidemic. It is essential to develop tools allowing for the early diagnosis of bruxism in an unobtrusive manner. This work explores the feasibility of detecting bruxism-related events using earables in a mimicked in-the-wild setting. Using inertial measurement unit for data collection, we utilise traditional machine learning for teeth grinding and clenching detection. We observe superior performance of models based on gyroscope data, achieving an 88% and 66% accuracy on grinding and clenching activities, respectively, in a controlled environment, and 76% and 73% on grinding and clenching, respectively, in an in-the-wild environment.\",\n \"Title: FastICARL - Fast Incremental Classifier and Representation Learning with Efficient Budget Allocation in Audio Sensing Applications.\\nYear: 2021\\n\\nAbstract: Various incremental learning (IL) approaches have been proposed to help deep learning models learn new tasks/classes continuously without forgetting what was learned previously (i.e., avoid catastrophic forgetting). With the growing number of deployed audio sensing applications that need to dynamically incorporate new tasks and changing input distribution from users, the ability of IL on-device becomes essential for both efficiency and user privacy. However, prior works suffer from high computational costs and storage demands which hinders the deployment of IL on-device. In this work, to overcome these limitations, we develop an end-to-end and on-device IL framework, FastICARL, that incorporates an exemplar-based IL and quantization in the context of audio-based applications. We first employ k-nearest-neighbor to reduce the latency of IL. Then, we jointly utilize a quantization technique to decrease the storage requirements of IL. We implement FastICARL on two types of mobile devices and demonstrate that FastICARL remarkably decreases the IL time up to 78-92% and the storage requirements by 2-4 times without sacrificing its performance. FastICARL enables complete on-device IL, ensuring user privacy as the user data does not need to leave the device.\",\n \"Title: OESense: employing occlusion effect for in-ear human sensing\\nYear: 2021\\n\\nAbstract: ABSTRACTSmart earbuds are recognized as a new wearable platform for personal-scale human motion sensing. However, due to the interference from head movement or background noise, commonly-used modalities (e.g. accelerometer and microphone) fail to reliably detect both intense and light motions. To obviate this, we propose OESense, an acoustic-based in-ear system for general human motion sensing. The core idea behind OESense is the joint use of the occlusion effect (i.e., the enhancement of low-frequency components of bone-conducted sounds in an occluded ear canal) and inward-facing microphone, which naturally boosts the sensing signal and suppresses external interference. We prototype OESense as an earbud and evaluate its performance on three representative applications, i.e., step counting, activity recognition, and hand-to-face gesture interaction. With data collected from 31 subjects, we show that OESense achieves 99.3% step counting recall, 98.3% recognition recall for 5 activities, and 97.0% recall for five tapping gestures on human face, respectively. We also demonstrate that OESense is compatible with earbuds' fundamental functionalities (e.g. music playback and phone calls). In terms of energy, OESense consumes 746 mW during data recording and recognition and it has a response latency of 40.85 ms for gesture recognition. Our analysis indicates such overhead is acceptable and OESense is potential to be integrated into future earbuds.\",\n \"Title: Anticipatory Detection of Compulsive Body-focused Repetitive Behaviors with Wearables\\nYear: 2021\\n\\nAbstract: Body-focused repetitive behaviors (BFRBs), like face-touching or skin-picking, are hand-driven behaviors which can damage one's appearance, if not identified early and treated. Technology for automatic detection is still under-explored, with few previous works being limited to wearables with single modalities (e.g., motion). Here, we propose a multi-sensory approach combining motion, orientation, and heart rate sensors to detect BFRBs. We conducted a feasibility study in which participants (N=10) were exposed to BFRBs-inducing tasks, and analyzed 380 mins of signals(1) under an extensive evaluation of sensing modalities, cross-validation methods, and observation windows. Our models achieved an AUC > 0.90 in distinguishing BFRBs, which were more evident in observation windows 5 mins prior to the behavior as opposed to 1-min ones. In a follow-up qualitative survey, we found that not only the timing of detection matters but also models need to be context-aware, when designing just-in-time interventions to prevent BFRBs.\",\n \"Title: PilotEar: Enabling In-ear Inertial Navigation\\nYear: 2021\\n\\nAbstract: ABSTRACT Navigation systems are used daily. While different types of navigation systems exist, inertial navigation systems (INS) have favorable properties for some wearables which, for battery and form factors may not be able to use GPS. Earables (aka ear-worn wearables) are living a momentum both as leisure devices, and sensing and computing platforms. The inherent high signal to noise ratio (SNR) of ear-collected inertial data, due to the vibration dumping of the musculoskeletal system; combined with the fact that people typically wear a pair of earables (one per ear) could offer significant accuracy when tracking head movements, leading to potential improvements for inertial navigation. Hence, in this work, we investigate and propose PilotEar, the first end-to-end earable-based inertial navigation system, achieving an average tracking drift of for one earable and for two earables.\",\n \"Title: Enabling On-Device Smartphone GPU based Training: Lessons Learned\\nYear: 2022\\n\\nAbstract: Deep Learning (DL) has shown impressive performance in many mobile applications. Most existing works have focused on reducing the computational and resource overheads of running Deep Neural Networks (DNN) inference on resource-constrained mobile devices. However, the other aspect of DNN operations, i.e. training (forward and backward passes) on smartphone GPUs, has received little attention thus f...\",\n \"Title: Breaking away from labels: The promise of self-supervised machine learning in intelligent health\\nYear: 2022\\n\\nAbstract: Medicine is undergoing an unprecedented digital transformation, as massive amounts of health data are being produced, gathered, and curated, ranging from in-hospital (e.g., intensive care unit [ICU]) to person-generated data (wearables). Annotating all these data for training purposes in order to feed to deep learning models for pattern recognition is impractical. Here, we discuss some exciting recent results of self-supervised learning (SSL) applications to high-resolution health signals. These examples leverage unlabeled data to learn meaningful representations that can generalize to situations where the ground truth is inadequate or simply infeasible to collect due to the high burden or associated costs. The most prominent bottleneck of deep learning today is access to labeled, carefully curated datasets, and self-supervision on health signals opens up new possibilities to eliminate data silos through general-purpose models that can transfer to low-resource environments and tasks.\",\n \"Title: YONO: Modeling Multiple Heterogeneous Neural Networks on Microcontrollers\\nYear: 2022\\n\\nAbstract: Internet of Things (IoT) systems provide large amounts of data on all aspects of human behavior. Machine learning techniques, especially deep neural networks (DNN), have shown promise in making sense of this data at a large scale. Also, the research community has worked to reduce the computational and resource demands of DNN to compute on low-resourced micro controllers (MCUs). However, most of the current work in embedded deep learning focuses on solving a single task efficiently, while the multi-tasking nature and applications of IoT devices demand systems that can handle a diverse range of tasks (such as activity, gesture, voice, and context recognition) with input from a variety of sensors, simultaneously. In this paper, we propose YONO, a product quantization (PQ) based approach that compresses multiple heterogeneous models and enables in-memory model execution and model switching for dissimilar multi-task learning on MCUs. We first adopt PQ to learn codebooks that store weights of different models. Also, we propose a novel network optimization and heuristics to maximize the com-pression rate and minimize the accuracy loss. Then, we develop an online component of YONO for efficient model execution and switching between multiple tasks on an MCU at run time without relying on an external storage device. YONO shows remarkable performance as it can compress multiple heterogeneous models with negligible or no loss of accuracy up to 12.37x. Furthermore, YONO's online component enables an efficient execution (latency of 16–159 ms and energy consumption of 3.8-37.9 mJ per operation) and reduces modelloading/switching la-tency and energy consumption by 93.3-94.5% and 93.9-95.0%, respectively, compared to external storage access. Interestingly, YONO can compress various architectures trained with datasets that were not shown during YONO's offline codebook learning phase showing the generalizability of our method. To summarize, YONO shows great potential and opens further doors to enable multi-task learning systems on extremely resource-constrained devices.\",\n \"Title: Improving Feature Generalizability with Multitask Learning in Class Incremental Learning\\nYear: 2022\\n\\nAbstract: Many deep learning applications, like keyword spotting, require the incorporation of new concepts (classes) over time, referred to as Class Incremental Learning (CIL). The major challenge in CIL is catastrophic forgetting, i.e., preserving as much of the old knowledge as possible while learning new tasks. Various techniques, such as regularization, knowledge distillation, and the use of exemplars, have been proposed to resolve this issue. However, prior works primarily focus on the incremental learning step, while ignoring the optimization during the base model training. We hypothesize that a more transferable and generalizable feature representation from the base model would be beneficial to incremental learning. In this work, we adopt multitask learning during base model training to improve the feature generalizability. Specifically, instead of training a single model with all the base classes, we decompose the base classes into multiple subsets and regard each of them as a task. These tasks are trained concurrently and a shared feature extractor is obtained for incremental learning. We evaluate our approach on two datasets under various configurations. The results show that our approach enhances the average incremental learning accuracy by up to 5.5%, which enables more reliable and accurate keyword spotting over time. Moreover, the proposed approach can be combined with many existing techniques and provides additional performance gain.\",\n \"Title: Stress Inference from Abdominal Sounds using Machine Learning.\\nYear: 2022\\n\\nAbstract: Stress is often considered the 21 century's epidemic, affecting more than a third of the globe's population. Long-term exposure to stress has significant side effects on physical and mental health. In this work we propose a methodology for detecting stress using abdominal sounds. For this study, eight participants were either exposed to a stressful (Stroop test) or a relaxing (guided meditation) stimulus for ten days. In total, we collected 104 hours of abdominal sounds using a custom wearable device in a belt form-factor. We explored the effect of various features on the binary stress classification accuracy using traditional machine learning methods. Namely, we observed the impact of using acoustic features on their own, as well as in combination with features representing current mood state, and hand-crafted domain-specific features. After feature extraction and reduction, by utilising a multilayer perceptron classifier model we achieved 77% accuracy in detecting abdominal sounds under stress exposure. Clinical relevance- This feasibility study confirms the link between the gastrointestinal system and stress and uncovers a novel approach for stress inference via abdominal sounds using machine learning.\",\n \"Title: Towards Adversarial Robustness with Early Exit Ensembles\\nYear: 2022\\n\\nAbstract: Deep learning techniques are increasingly used for decision-making in health applications, however, these can easily be manipulated by adversarial examples across different clinical domains. Their security and privacy vulnerabilities raise concerns about the practical deployment of these systems. The number and variety of the adversarial attacks grow continuously, making it difficult for mitigation approaches to provide effective solutions. Current mitigation techniques often rely on expensive re-training procedures as new attacks emerge. In this paper, we propose a novel adversarial mitigation technique for biosignal classification tasks. Our approach is based on recent findings interpreting early exit neural networks as an ensemble of weight sharing sub-networks. Our experiments on state-of-the-art deep learning models show that early exit ensembles can provide robustness generalizable to various white box and universal adversarial attacks. The approach increases the accuracy of vulnerable deep learning models up to 60 percentage points, while providing adversarial mitigation comparable to adversarial training. This is achieved without previous exposure to the adversarial perturbation or the computational burden of re-training.\",\n \"Title: Mobile Health With Head-Worn Devices: Challenges and Opportunities\\nYear: 2022\\n\\nAbstract: Monitoring human behavior and health status using mobile devices, a.k.a. Mobile Health, has gained increasing attention from both academia and industry in recent years. It allows imperceptible health tracking from the users and remote health management from the healthcare service providers. Head-worn devices, such as earbuds, glasses, and brain–computer interfaces, exhibit great potential for mobile health due to their advantageous wearing position, the human head, which is motion-resilient and full of human biosignals. Although initial attempts have been conducted for different healthcare applications with head-worn devices, this fast-growing area is still underexplored and retains great promises. With this work, we investigate the most pressing challenges to fully exploit the potential of head-worn devices for mobile health, from the perspective of sensing, computing, and system design. Our exploration reveals key guidelines and lessons to inform future efforts in this space.\",\n \"Title: Women in Networks: Professor Cecilia Mascolo\\nYear: 2022\\n\\nAbstract: Cecilia Mascolo is Professor of Mobile Systems in the Department of Computer Science and Technology, University of Cambridge, United Kingdom. She is a Director of the Centre for Mobile, Wearable System and Augmented Intelligence and a Fellow of Jesus College Cambridge.\",\n \"Title: Exploring On-Device Learning Using Few Shots for Audio Classification\\nYear: 2022\\n\\nAbstract: Few shot learning (FSL) improves the generalization of neural network classifiers to unseen classes and tasks using small annotated samples of data. Recently, there have been attempts to apply few shot learning in the audio domain for various applications. However, the focus has been mainly on accuracy. Here, we take a holistic view and investigate various system aspects such as latency, storage and memory requirements of few shot learning methods in addition to improving the accuracy with very deep learning models for the tasks of audio classification. To this end, we not only compare the performance of different few shot learning methods but also, for the first time, design an end-to-end framework for smartphones and wearables which can run such methods completely on-device. Our results indicate the need to collect large datasets with more classes as we show much higher gains can be obtained with very deep learning models on big datasets. Surprisingly, metric-based methods such as ProtoTypical Networks can be realized practically on-device and quantization helps further (50%) in reducing the resource requirements, while having no impact on accuracy for the audio classification tasks.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":166,"string":"166"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":49,"string":"49"}}},{"rowIdx":50,"cells":{"question_id":{"kind":"string","value":"Gary McGraw"},"question":{"kind":"string","value":"Generate an abstract for the title \"Risk Analysis in Software Design\" using the following items: 1. Software development\n2. Software vendors\n3. Positive features\n4. Designing software\n5. Improving business processes"},"answer":{"kind":"string","value":"Software development is all about making software do something: when software vendors sell their products, they talk about what the particular products do to make customer's lives easier, such as improving business processes or something similarly positive. Following this trend, most systems for designing software also tend to describe positive features."},"correct_answer":{"kind":"string","value":"Software development is all about making software do something: when software vendors sell their products, they talk about what the particular products do to make customer's lives easier, such as improving business processes or something similarly positive. Following this trend, most systems for designing software also tend to describe positive features."},"documents":{"kind":"list like","value":["Title: Software Penetration Testing\nYear: 2005\n\nAbstract: Quality assurance and testing organizations are tasked with the broad objective of assuring that a software application fulfills its functional business requirements. Such testing most often involves running a series of dynamic functional tests, to ensure proper implementation of the applicationýs features. However, because security is not a feature or even a set of features, security testing doesn't directly fit into this paradigm.","Title: Software Security Testing\nYear: 2004\n\nAbstract: Security testing has recently moved beyond the realm of network port scanning to include probing-softwareýs behavior as a critical aspect of system behavior. Unfortunately, testing software security is a commonly misunderstood task. Security testing done properly goes deeper than simple black-box probing on the presentation layer (the sort performed by so-called application security tools)-even beyond the functional testing of security apparatuses. Testers must use a risk-based approach, grounded in both the systemýs architectural reality and the attackerýs mindset, to adequately gauge software security. By identifying risks in the system and creating tests driven by those risks, a software security tester can properly focus on those areas of code in which an attack will succeed. This approach provides a higher level of software security assurance than possible with classical black-box testing.","Title: Managing Software Security Risks\nYear: 2002\n\nAbstract: Most organizations manage computer security risk reactively by investing in technologies designed to protect against known system vulnerabilities and monitor intrusions as they occur. However, firewalls, cryptography, and antivirus protection address the symptoms, not the root cause, of most security problems. Buying and maintaining a firewall, for example, is ineffective if external users can access remotely exploitable Internet-enabled applications through it. Because hackers attack software, improving computer security depends on proactively managing risks associated with software and software development. The current \"penetrate and patch\" approach of fixing broken software only after it has been compromised is insufficient to control the problem","Title: Guest Editors' Introduction: Securing Online Games: Safeguarding the Future of Software Security\nYear: 2009\n\nAbstract: Massively distributed online role-playing games are a bellwether for problems to come in software security. As cloud computing, service-oriented architecture, and Web 2.0 take off, we can expect to grapple with very similar technical issues to those currently facing online games. The guest editors of this special issue on securing online games tackle this problem from three angles, describing the articles they've lined up to address money and virtual economies, the nascent state of the law, and thorny technical issues.","Title: Knowledge for Software Security\nYear: 2005\n\nAbstract: A critical challenge facing software security today is the dearth of experienced practitioners. Approaches that rely solely on apprenticeship as a method of propagation won't scale quickly enough to address this burgeoning problem, so as the field evolves and establishes best practices, knowledge management can play a central role in encapsulating and spreading the emerging discipline more efficiently. This article is about the kinds of security knowledge that can provide a solid foundation for software security practices.","Title: Software Assurance for Security\nYear: 1999\n\nAbstract: The article discusses an approach to security analysis that we have applied successfully over the past several years (to 1999) at Reliable Software Technologies. Our approach is no magic bullet, but it offers a reasoned methodology that has proven to be useful in the trenches. Our methodology, like many useful things, is a mix of art and engineering. The idea is straightforward: design a system with security in mind, analyze the system in light of known and anticipated risks, rank the risks according to their severity, test to the risks, and cycle broken systems back through the design process. The process outlined above has one essential underlying goal: avoiding the unfortunately pervasive penetrate-and-patch approach to computer security-that is, avoiding the problem of desperately trying to come up with a fix to a problem that is being actively exploited by attackers. In simple economic terms, finding and removing bugs in a software system before its release is orders of magnitude cheaper and more effective than trying to fix systems after release","Title: Static Analysis for Security\nYear: 2004\n\nAbstract: All software projects are guaranteed to have one artifact in common: source code. Together with architectural risk analysis, code review for security ranks very high on the list of software security best practices. Here, we'll look at how to automate source-code security analysis with static analysis tools.","Title: Online Games and Security\nYear: 2007\n\nAbstract: Gaming has always been (and remains) a prime driver of PC technology, with deep penetration into the consumer market. Yet, online games -- especially massively multiplayer online role-playing games (MMORPGs) -- suffer from various security problems. This introduction to MMORPG security focuses on bugs involving time and state -- bugs that will likely appear more frequently as real-world software evolves to become more like game software.","Title: Statically Scanning Java Code: Finding Security Vulnerabilities\nYear: 2000\n\nAbstract: Developers and users require some degree of assurance in their applications' security vulnerabilities. The authors have designed a prototype tool, Jslint, to help programmers automatically use existing security knowledge.","Title: Technology Transfer: A Software Security Marketplace Case Study\nYear: 2011\n\nAbstract: Gary McGraw is one of those astounding people you meet in our industry—a technical wizard who's also a musician (check out Where's Aubrey www.wheresaubrey.com) and a chef. He has, in effect, defined software security with a process that is true science in action (check out the BSIMM at www.cigital.com/services/bsimm/). He's one of the most thought-provoking yet entertaining speakers and writers I know. I'm happy to include his contribution in the Insights series.","Title: Wouldn't it be nice to have software labels\nYear: 2010\n\nAbstract: No abstract available.","Title: Automated Code Review Tools for Security\nYear: 2008\n\nAbstract: Static analysis identifies many common coding problems automatically, before a program is released.","Title: A 'Crystal Ball' for Software Liability\nYear: 1997\n\nAbstract: Software developers are living in a liability grace period, but it won't last. To adequately insure themselves against potential liability, developers need tools to identify worst-case scenarios and help them quantify the risks associated with a piece of software. For assessing such risks associated with software, the authors recommend fault injection, which provides worst-case predictions about how badly a piece of code might behave and how frequently it might behave that way. By contrast, software testing states how good software is. But even correct code can have \"bad days,\" when external influences keep it from working as desired. Fault injection is arguably the next best thing to having a crystal ball, and it certainly beats facing the future with no predictions at all. It should be a regular part of risk assessment. The greatest benefit from fault injection occurs when a piece of software does not tolerate injected anomalies. False optimism gives way to the only honest claim-that the software presents risks.","Title: Silver Bullet Speaks with Ed Felten\nYear: 2006\n\nAbstract: Featured here is an excerpt adapted from the full interview between Felten and Silver Bullet host Gary McGraw. Their conversation ranged widely, from Felten's technology predictions and his thoughts on public policy and law all the way to raising kids.","Title: Silver Bullet Speaks with Dorothy Denning\nYear: 2007\n\nAbstract: Gary McGraw speaks with Dorothy Denning in a wide-ranging conversation that covers teaching computer security to the Big Sur Power Walk.","Title: Silver Bullet Speaks with Dan Geer\nYear: 2006\n\nAbstract: Dan Geer discusses his work in Project Athena and his thoughts on data security.","Title: Silver Bullet Speaks to Avi Rubin\nYear: 2006\n\nAbstract: Avi Rubin discusses his favorite projects, including the SpeedPass hack and electronic voting.","Title: Silver Bullet Talks with John Savage\nYear: 2011\n\nAbstract: Gary McGraw interviews John Savage, the An Wang Professor of Computer Science at Brown University. Savage served as a Jefferson Science Fellow in the US Department of State during the 2009–2010 academic year. In his lengthy career, he has held many positions and received several honors for his work in theoretical computer science and computational nanotechnology. His latest book is Models of Computation: Exploring the Power of Computing. Hear the full podcast at www.computer.org/silverbullet or www. cigital.com/silverbullet.","Title: Silver Bullet Talks with Jon Swartz\nYear: 2008\n\nAbstract: Silver Bullet host Gary McGraw chats with USA Today reporter, Jon Swartz about security.","Title: Silver Bullet Talks with Jeremiah Grossman\nYear: 2009\n\nAbstract: Silver Bullet Security Podcast host Gary McGraw interviews Jeremiah Grossman, founder and CTO of WhiteHat Security, who is well known for his work in Web application security.","Title: Silver Bullet Talks with Jon Callas.\nYear: 2014\n\nAbstract: Jon Callas, chief technology officer at Silent Circle, talks to Gary McGraw about the early days of computing, nascent cryptography, Lavabit, Edward Snowden, and software security versus reality. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Kay Connelly\nYear: 2012\n\nAbstract: Gary McGraw interviews Kay Connelly, who, at the time of this interview, is an associate professor of computer science at Indiana University and senior associate director of IU's Center for Applied Cybersecurity Research. She describes why in situ usability study is important, the ETHOS living lab, and her advice to women interested in pursuing a career in computer science. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Halvar Flake\nYear: 2011\n\nAbstract: Gary McGraw interviews Halvar Flake. Before moving over to Google, Halvar Flake ran Zynamics,a company specializing in reverse engineering tools, as an independent researcher and consultant focused on reverse engineering and vulnerability discovery. Flake has spoken at RSA, Black Hat, CanSecWest, and other venues; he has also taught classes on code analysis, reverse engineering, and vulnerability analysis for independent software vendors and governments. Hear the full podcast at www.computer.org/silverbullet or www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Howard Schmidt\nYear: 2012\n\nAbstract: Gary McGraw interviews Howard Schmidt, former cybersecurity coordinator for the Obama administration. They discuss the differences between doing security work in the public and private sectors, the difficulties of establishing cybersecurity in the government, and how the actions of Anonymous and Wikileaks square with the notion of free speech. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Giovanni Vigna\nYear: 2012\n\nAbstract: Gary McGraw interviews Giovanni Vigna, a professor of computer science at the University of California, Santa Barbara, where he works on Web security, vulnerability analysis, malware countermeasures, and intrusion detection. Vigna is also codirector of the UCSB Security Lab and a member of the Shellphish and Epic Fail hacker collectives. He cofounded Lastline (an antimalware company) and organizes the annual International Capture the Flag hacking competition (iCTF). Hear the full podcast series at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Gary Warzala\nYear: 2013\n\nAbstract: Gary McGraw interviews Gary Warzala, Visa's chief information security officer. He talks about the daily life of a CISO, how companies can attract and retain good security employees, and how to measure security and discuss the results with management. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Iván Arce\nYear: 2010\n\nAbstract: Silver Bullet Security Podcast host Gary McGraw interviews Iván Arce, chief technology officer of Core Security Technologies.","Title: Silver Bullet Talks with Fred Schneider\nYear: 2009\n\nAbstract: Gary McGraw talks with associate editor in chief of S&P Fred Schneider of Cornell University about security and reliability, trust, and diversity in software systems.","Title: Silver Bullet Talks with Gunnar Peterson\nYear: 2009\n\nAbstract: Gary McGraw interviews Gunnar Peterson, a software security expert and a managing principal at Arctec Group, a Minneapolis-based consulting firm. His work centers around service-oriented architecture (SOA), Web 2.0, and other distributed systems. Peterson's blog, http://1raindrop.typepad.com, is devoted to topics in software security. He also edits IEEE Security & Privacy magazine's Building Security In column with John Stevens from Cigital and Deborah Frincke..","Title: Silver Bullet Talks with Greg Morrisett\nYear: 2010\n\nAbstract: Gary McGraw interviews Greg Morrisett, the Allen B. Cutting Professor of Computer Science and associate dean for computer science and engineering at Harvard University. His current work is on applications of advanced type systems, model checkers, proof-carrying code, and inline reference monitors for building efficient and provably secure systems. He's also working on languages for sensor networks. Hear the full podcast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is the full transcript of the interview.","Title: Silver Bullet Talks with Gillian Hayes\nYear: 2010\n\nAbstract: Gary Mc Graw interviews Gillian Hayes. She is an assistant professor in Informatics at the Bren School of Information and Computer Sciences at University of California, Irvine (UCI). She's director of the Social and Technological Action Research Group, otherwise known as \"STAR.\" Hear the full podcast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is the full transcript of the interview.","Title: Silver Bullet Talks with Elinor Mills\nYear: 2011\n\nAbstract: Gary McGraw talks with Elinor Mills, a senior writer at CNET (www.news.com), where she covers Internet technology and security. She has written about technology for several outlets over the past 20 years, including Reuters, the Associated Press, the Industry Standard, and IDG. The 2010 Apollo Research Security Survey placed Mills at the top of its list of journalists who reach the largest audience when writing about security. Hear the full podcast at www.computer.org/silverbullet or www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Ed Amoroso\nYear: 2008\n\nAbstract: Gary McGraw interviews Ed Amoroso, AT&T's chief information security officer. Their conversation ranged widely, from system design to privacy.","Title: Silver Bullet Talks with David Rice\nYear: 2011\n\nAbstract: Gary McGraw interviews David Rice, formerly the executive director of The Monterey Group, a strategic consulting firm that focuses its services on cybersecurity and identity management. Now the director of global security at Apple, Rice has also served as a global network vulnerability analyst for the US National Security Agency and was a special duty cryptologic officer for the US Navy. Rice wrote Geekonomics: The Real Cost of Insecure Software (Addison-Wesley, 2007) and speaks at many events around the world. Hear the full podcast at www.computer.org/silverbullet or www. cigital.com/silverbullet.","Title: Silver Bullet Talks with Adam Shostack\nYear: 2008\n\nAbstract: Gary McGraw interviews Adam Shostack. Shostack is a member of Microsoft's Secure Development Lifecycle Team. He's worked for Zero Knowledge as Most Evil Genius and Reflective where, as CTO, he focused on static analysis for software security. Shostack recently coauthored The New School of Information Security with Andrew Stewart.","Title: Silver Bullet Talks with Becky Bace\nYear: 2007\n\nAbstract: Gary McGraw speaks with Becky Bace. Their conversation ranged widely, from explosives to vulnerability disclosure to venture capital.","Title: Silver Bullet Talks with Christofer Hoff\nYear: 2010\n\nAbstract: Gary McGraw interviews Christofer Hoff, the director of cloud and virtualizations solutions at Cisco. He has also been a chief security architect at Unisys, a chief architect, a CSO, and a CTO. Hoff has a well-trafficked blog at www.rationalsurvivability.com/blog. The Web extra includes the full interview. The audio interview is available here: www.computer.org/security/silverbullet/.","Title: Silver Bullet Talks with Annie Antón\nYear: 2007\n\nAbstract: Gary McGraw interviews Annie Antón.","Title: Silver Bullet Talks with Wenyuan Xu\nYear: 2013\n\nAbstract: Wenyuan Xu, as associate professor at the University of South Carolina, talks about the differences between American and Chinese technical culture, her work on automatic meter reading systems, whether electrical engineering is more advanced in terms of design than computer science, and why there are so few women in engineering and computer science. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Virgil Gligor\nYear: 2009\n\nAbstract: Gary McGraw interviews Virgil Gligor, a professor in Carnegie Mellon University's (CMU) Department of Electrical and Computer Engineering. He's also codirector of CyLab (www.cylab.cmu.edu). Gligor serves on Microsoft's Trusted Computing Academic Advisory Board and has consulted with Burroughs and IBM. Gligor has served on many government information security study groups and served on the National Research Council's Panel on Information Security.","Title: Silver Bullet talks with Thomas Rid\nYear: 2013\n\nAbstract: Gary McGraw interviews Thomas Rid, a Reader in War Studies at King's College London. Rid discusses how his life as a \"wandering academic\" influences his work, cyberwar, military dictionaries, and the problem of jargon. Rid has worked as a visiting scholar in Jerusalem, at the Wilson Center, at RAND, and at the Institut Fran&amp;#x00E7;ais de Relation International in Paris. He has PhD in political science from Humboldt University of Berlin; his books include Understanding Counterinsurgency, War 2.0, War and Media Operations. His new book, Cyber War Will Not Take Place, is out in the US with Oxford University Press in September 2013. He lives in London with his wife. The full podcast is at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Steve Bellovin\nYear: 2013\n\nAbstract: Gary McGraw interviews Steve Bellovin, professor of computer science at Columbia University and CTO of the Federal Trade Commission. They discuss technology transfer, how code has gotten better but the threat model has changed, whether mobile security is just a repackaging of the same security problem, the very first days of Usenet, and the famed Evil Bit. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Richard Clarke\nYear: 2010\n\nAbstract: Gary McGraw interviews Richard A. Clarke. Clarke is an internationally recognized expert on national security, counter terrorism, and cyber security. He's an on-air consultant for ABC news and teaches at the Kennedy School of Government. Clarke served for 11 consecutive years in the White House for three different presidents, including a stint as special advisor to the president for cybersecurity. Before his work in the White House, he worked in the Pentagon, the intelligence community, and the State Department. He's the author of a number of books, including Against All Enemies and his new book Cyber War (which is orange). Hear the full podcast or watch the videocast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is a full transcript of the interview.","Title: Silver Bullet Talks with Ross Anderson\nYear: 2007\n\nAbstract: Gary McGraw chats with Ross Anderson, professor of security engineering at the Computer Laboratory at Cambridge University and author of Security Engineering. Gary and Ross discuss the simple reasons why most systems fail, the economic imbalance between engineers/developers and a system's users, and why publicly describing attacks is essential to security engineering.","Title: Silver Bullet Talks with Ralph Langner\nYear: 2011\n\nAbstract: Gary McGraw interviews Ralph Langner, the founder and CEO of Langner Communications, a German company focused on control system security. He has more than 20 years' experience working with computerized control systems and was the first researcher to determine that Stuxnet was a directed cyberattack against Iran. Hear the full podcast at www.computer.org/security/podcasts or www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Randy Sabett\nYear: 2012\n\nAbstract: Gary McGraw talks to Randy Sabett, a lawyer with the ZwillGen cyberlaw firm in Washington, DC, about cybercrime and the law. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Paul Kocher\nYear: 2011\n\nAbstract: Gary McGraw interviews Paul Kocher, president and chief scientist of Cryptography Research. Among his many accomplishments, he helped design SSL 3.0, Electronic Frontier Foundation's DES cracker (nicknamed \"Deep Crack\"), and parts of the content security system found on Blu-ray discs. He continues to design crypto protocols and applications, which are then successfully deployed in real-world systems. Hear the full podcast at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet. The Web extra is a full transcript of the interview.","Title: Silver Bullet Talks with Neil Daswani\nYear: 2012\n\nAbstract: Gary McGraw interviews Neil Daswani, a manager in Twitter's revenue engineering team. He was formerly the CTO and cofounder of Dasient, an Internet security company that Twitter purchased in January 2012.","Title: Silver Bullet Talks with Matthew Green.\nYear: 2014\n\nAbstract: Matthew Green, an assistant research professor at Johns Hopkins Information Security Institute, talks about the difference between theoretical and applied cryptography, blogs, and back doors.","Title: Silver Bullet Talks with Matt Bishop\nYear: 2008\n\nAbstract: Gary McGraw interviews Matt Bishop, who has made significant inroads in the commercial side of security, lecturing for the SANS Institute, and focusing much of his writing on security education. He is the author of Computer Security: Art and Science (Addison-Wesley, 2002), an important textbook in the space. You can find additional podcasts in the series at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/.","Title: Lost Decade or Golden Era: Computer Security since 9/11\nYear: 2012\n\nAbstract: In the 10 years since 9/11, the cybersecurity threat has evolved significantly, and every sector of the US economy has become more dependent than ever on the Internet. Today, major security breaches dominate headlines on a weekly basis. Intrusion campaigns such as \"Operation Shady Rat\" (disclosed by McAfee in August) and \"Nitro\" (disclosed by Symantec in October) show a systematic compromise of every significant sector of the economy, including technology, industrial manufacturing, defense, financial services, and government and nongovernmental organizations. In addition to the systematic compromises of these sectors, we've also seen hints and speculation of cyberwarfare operations including Stuxnet, Duqu, and the recent loss and capture of the US RQ-170 Sentinel spy drone over Iran. But over the same 10-year time period, security technology has arguably improved incrementally, with innovation occurring in some areas. The question the authors attempt to address in this point/counterpoint article is whether we're better off today in security than we were 10 years ago.","Title: Processes for Producing Secure Software: Summary of US National Cybersecurity Summit Subgroup Report\nYear: 2004\n\nAbstract: This report summarizes work initiated at the National Cybersecurity Summit, held 2-3 December 2003 in Santa Clara, California. Attendees representing industry, academia, and the US Department of Homeland Security (DHS) formed five task forces to focus on specific topic areas. This report describes the key problems and recommendations identified by the Software Process subgroup of the \"Security across the Software Development Lifecycle\" task force.","Title: Token-based scanning of source code for security problems\nYear: 2002\n\nAbstract: We describe ITS4, a tool for statically scanning C and C++ source code for security vulnerabilities. Compared to other approaches, our scanning technique stakes out a new middle ground between accuracy and efficiency. This method is efficient enough to offer real-time feedback to developers during coding while producing few false negatives. Unlike other techniques, our method is also simple enough to scan C++ code despite the complexities inherent in the language. Using ITS4, we found new remotely exploitable vulnerabilities in a widely distributed software package as well as in a major piece of e-commerce software.We also describe functionality in more recent tools modeled after ITS4, and discuss algorithms that could easily be used to augment these kinds of tools. Particularly, we describe a solution we have prototyped that allows for more rigorous analysis of C and C++ source code, without failing to analyze parts of the program due to preprocessor conditionals.","Title: Will Openish Source Really Improve Security\nYear: 2000\n\nAbstract: Will openish source really improve security? No.","Title: Security as a new dimension in embedded system design\nYear: 2004\n\nAbstract: The growing number of instances of breaches in information security in the last few years has created a compelling case for efforts towards secure electronic systems. Embedded systems, which will be ubiquitously used to capture, store, manipulate, and access data of a sensitive nature, pose several unique and interesting security challenges. Security has been the subject of intensive research in the areas of cryptography, computing, and networking. However, despite these efforts, security is often mis-construed by designers as the hardware or software implementation of specific cryptographic algorithms and security protocols. In reality, it is an entirely new metric that designers should consider throughout the design process, along with other metrics such as cost, performance, and power..This paper is intended to introduce embedded system designers and design tool developers to the challenges involved in designing secure embedded systems. We attempt to provide a unified and holistic view of embedded system security by first analyzing the typical functional security requirements for embedded systems from an end-user perspective. We then identify the implied challenges for embedded system architects, as well as hardware and software designers (e.g., tamper-resistant embedded system design, processing requirements for security, impact of security on battery life for battery-powered systems, etc.). We also survey solution techniques to address these challenges, drawing from both current practice and emerging research, and identify open research problems that will require innovations in embedded system architecture and design methodologies.","Title: Interview: Software Security in the Real World\nYear: 2010\n\nAbstract: In an interview conducted by Computer editorial board member Ann E.K. Sobel, Cigital CTO Gary McGraw discusses the state of software security and the BSIMM—a data-driven research project describing and measuring what successful organizations are doing to ensure software security.","Title: Letter Spirit: An Architecture for Creativity in an Microdomain\nYear: 1993\n\nAbstract: The Letter Spirit project explores the creative act of artistic letter-design. The aim is to model how the 26 lowercase letters of the roman alphabet can be rendered in many different but internally coherent styles. Viewed from a distance, the behavior of the program can be seen to result from the interaction of four emergent agents working together to form a coherent style and to design a complete alphabet: the Imaginer (which plays with the concepts behind letterforms), the Drafter (which converts ideas for letterforms into graphical realizations), the Examiner (which combines bottom-up and top-down processing to perceive and categorize letterforms), and the Adjudicator (which perceives and dynamically builds a representation of the evolving style). Creating a gridfont is an iterative process of guesswork and evaluation carried out by the four agents. This process is the central feedback loop of creativity. Implementation of Letter Spirit is just beginning. This paper outlines our goals and plans for the project.","Title: Silver Bullet Talks with Per-Olof Persson\nYear: 2013\n\nAbstract: Gary McGraw interviews Per-Olof Persson, currently head of global software security operations at Sony Mobile. Persson discusses the importance of working in different positions within the same company—from directing the Sony Board to running in front of Android phones. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with W. Hord Tipton\nYear: 2013\n\nAbstract: Gary McGraw talks with W. Hord Tipton, executive director of (ISC)2, about how he got into science and engineering, the insights he's cultivated from being a nuclear and chemical engineer, whether or not certification can help advance software security, and the benefits of teaching software security to kids. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Attacking Malicious Code: A Report to the Infosec Research Council\nYear: 2000\n\nAbstract: The accelerating trends of interconnectedness, complexity, and extensibility are aggravating the already-serious threat posed by malicious code. To combat malicious code, these authors argue for creating sound policy about software behavior and enforcing that policy through technological means.","Title: Bridging the Gap between Software Development and Information Security\nYear: 2005\n\nAbstract: Traditionally, software development efforts in large corporations have been about as far removed from information security as they were from human resources or any other business function. The disconnect between security and development has ultimately produced software development efforts that lack any sort of contemporary understanding of technical security risks. Today's complex and highly connected computing environments trigger myriad security concerns, so by blowing off the idea of security entirely, software builders virtually guarantee that their creations will have way too many security weaknesses that could--and should--have been avoided. This article presents some recommendations for solving this problem.","Title: Predicting How Badly \"Good\" Software Can Behave\nYear: 1997\n\nAbstract: This paper presents a fault-injection methodology that predicts how software will behave when: (1) componentsof the software fail, (2) hardware components external to the software fail, (3) human factor errorsoccur and bad input is provided to the software, and (4) the software is executing in unlikely operationalmodes. Because of the enterprise-critical nature of many of today's software systems, it is vital that thesesystem are robust enough to handle problems that originate externally as ...","Title: Silver Bullet Talks with Brian Krebs\nYear: 2015\n\nAbstract: Gary McGraw talks to Brian Krebs of KrebsOnSecurity.com about security breaches, malware, cybercrime, and getting the general public more involved in cybersecurity.","Title: Silver Bullet Talks with Yoshi Kohno.\nYear: 2014\n\nAbstract: nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull...","Title: Silver Bullet Talks with the IEEE Center for Secure Design.\nYear: 2014\n\nAbstract: The IEEE Center for Secure Design (CSD), which launched in August 2014, gathers software security expertise from industry, academia, and government and provides guidance on recognizing design flaws and building security in. Three of the founding members of the CSD discuss the project and its future. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.","Title: Silver Bullet Talks with Whitfield Diffie\nYear: 2015\n\nAbstract: Gary McGraw talks to Whitfield Diffie, co-creator of the Diffie-Hellman public-key exchange method, about his career in cryptography and the future of privacy.","Title: Privacy and security in a networked world\nYear: 2014\n\nAbstract: As news stories continue to demonstrate, ensuring adequate security and privacy in a networked \\\"always on\\\" world is a challenge; and while open source software can mitigate problems, it is not a panacea. This panel will bring together experts from industry and academia to debate, discuss, and offer opinions -- questions might include: What are the \\\"costs\\\" of \\\"good enough\\\" security and privacy on developers and customers? What is the appropriate trade-off between the price provide security and cost of poor security? How can the consequences of poor design and implementation be managed? Can systems be enabled to fail \\\"security-safe\\\"? What are the trade-offs for increased adoption of privacy and security best practices? How can the \\\"costs\\\" of privacy and security -- both tangible and intangible -- be reduced?","Title: Security Fatigue? Shift Your Paradigm\nYear: 2014\n\nAbstract: Software security is the fastest growing paradigm in the IT security field, and the Building Security in Maturity Model (BSIMM) project offers real-world measurements for assessment.","Title: From the ground up: the DIMACS software security workshop\nYear: 2003\n\nAbstract: The recent DIMACS Software Security Workshop explored issues such as security engineering, architecture and implementation risks, security analysis, mobile and malicious code, education and training, and open research issues. Many promising techniques have grown from connections between computer security, programming languages, and software engineering, and one workshop goal was to bring these communities closer together to crystallize the software security subfield. The author reports the workshop's results in this article.","Title: Guest Editors' Introduction: Why Attacking Systems Is a Good Idea\nYear: 2004\n\nAbstract: The articles in this issue represent the broad range of ideas that come to mind when scientists and engineers think about attacking systems. Some approach the problem by describing technically sophisticated attacks, attack patterns, and toolkits. Others fret about the politics of security and attacks, worrying that outlawing certain kinds of software will backfire. Some describe methodologies for breaking systems (on purpose) in order to evaluate them. Others describe in gory detail the kinds of tools the adversary regularly wields. All of these approaches are useful.","Title: Adopting a software security improvement program\nYear: 2005\n\nAbstract: Leading software shops (including Microsoft) are working hard to improve the way they build security into their products. Software security initiatives have proven beneficial for those organizations that have implemented them. Such initiatives involve the adoption and rollout of various types of best practices. The article describes an approach that works, with an emphasis on business process engineering that might be unfamiliar to technical practitioners. By following some commonsense steps, a software security improvement program has a greater chance of achieving its ultimate goal: software security that makes business sense.","Title: Software security and SOA: danger, Will Robinson!\nYear: 2006\n\nAbstract: The current buzzword of choice among the technical elite (at least those subject to marketing departments) is service-oriented architecture, or SOA (pronounced 'SO-uh'). As SOA moves from hype to practice, an opportunity exists to do security right, but a similar opportunity exists for disaster if security is done wrong. This article describes 13 snares that we must avoid to end up with SOA security that makes sense.","Title: Interview: Silver Bullet Speaks to Marcus Ranum\nYear: 2006\n\nAbstract: In the third episode of the Silver Bullet Security Podcast, Gary talks with Marcus Ranum, who is an acclaimed security guru widely credited with inventing the proxy firewall. Marcus and Gary discuss why Marcus thinks we're not making progress in the computer security field, how common sense would help computer security, and Richard Feynman.","Title: Silver Bullet Talks with Steven Kent\nYear: 2010\n\nAbstract: Steven Kent is Chief Scientist for Information Security at BBN Technology, a division of Raytheon, where he's been engaged in network security research and development for several decades. Kent is a wellknown security researcher who's work ranges from end-to-end encryption and access control systems for packet networks, through design of secure transport later and electronic message protocols, to performance analysis of security mechanisms.","Title: Four Software Security Findings\nYear: 2016\n\nAbstract: Analyzing data from 78 firms using the Building Security In Maturity Model (BSIMM) revealed four truths about software security that will help firms protect and secure their assets.","Title: Silver Bullet Talks with L. Jean Camp\nYear: 2015\n\nAbstract: Gary McGraw talks to L. Jean Camp about translucent security; risk management; and security-related issues affecting usability, economics, and senior citizens.","Title: Silver Bullet Talks with Steven M. Bellovin and Matthew Green\nYear: 2015\n\nAbstract: Gary McGraw sits down with security gurus Steven M. Bellovin and Matthew Green, coauthors of the report \"Keys under Doormats: Mandating Insecurity by Requiring Government Access to All Data and Communications.\"","Title: Silver Bullet Talks with Peiter (Mudge) Zatko.\nYear: 2016\n\nAbstract: Gary McGraw interviews Peiter Zatko, known in the security community as Mudge, about the origins of the L0pht hacker collective, managing cybersecurity projects for DARPA, and much more.","Title: Silver Bullet Talks with Bart Preneel\nYear: 2015\n\nAbstract: Gary McGraw discusses cryptology and information security with Bart Preneel, a professor at one of the world's oldest universities.","Title: Silver Bullet Talks with Jamie Butler.\nYear: 2016\n\nAbstract: Gary McGraw talks to Jamie Butler, the chief technology officer and chief scientist at Endgame, about attacking back, rootkits, OS security, and more.","Title: Silver Bullet Talks with Katie Moussouris\nYear: 2015\n\nAbstract: Gary McGraw sits down with HackerOne chief policy officer Katie Moussouris to talk about bug bounties and vulnerability disclosures.","Title: Silver Bullet Talks with Jacob West.\nYear: 2016\n\nAbstract: Gary McGraw talks to Jacob West--chief architect for security products at NetSuite--about secure design, the critical difference between bugs and flaws, and wearable device security.","Title: Silver Bullet Talks with Martin Hellman.\nYear: 2016\n\nAbstract: Gary McGraw talks to the co-inventor of public-key cryptography, Martin Hellman, about his cutting-edge career, his involvement in the Crypto Wars, and his work with risk management and peace issues.","Title: Silver Bullet Talks with Jim Manico.\nYear: 2016\n\nAbstract: Gary McGraw sits down with Jim Manico of Manicode Security about static analysis, open source, and developer training.","Title: Silver Bullet Talks with Marie Moe.\nYear: 2017\n\nAbstract: Gary McGraw sits down with Marie Moe, a SINTEF research scientist and associate professor at the Norwegian University of Science and Technology, to talk about medical device security.","Title: Six Tech Trends Impacting Software Security.\nYear: 2017\n\nAbstract: The past few years have seen radical shifts in the way software is developed, in terms of both process and the technology stack. We must actively track these changes to ensure that software security solutions remain relevant.","Title: Silver Bullet Talks with Lesley Carhart.\nYear: 2017\n\nAbstract: Gary McGraw talks to Lesley Carhart about the information security community, digital forensics and incident response, future hackers, and more.","Title: Silver Bullet Talks with Kate Pearce.\nYear: 2017\n\nAbstract: Gary McGraw talks to Kate Pearce about the state of the software security industry, gender perspectives in the security space, the relationship between biology and security, and more.","Title: Silver Bullet Talks with Kelly Lum.\nYear: 2017\n\nAbstract: Gary McGraw talks to Kelly Lum about security engineering and her work at Tumblr.","Title: Silver Bullet Talks with Ksenia Dmitrieva-Peguero.\nYear: 2017\n\nAbstract: Gary McGraw talks to Synopsys’s Ksenia Dmitrieva-Peguero about software security awareness, the benefits and drawbacks of frameworks like AngularJS, her favorite security conferences, and more.","Title: Silver Bullet Talks with Nicole Perlroth.\nYear: 2017\n\nAbstract: Gary McGraw talks to Nicole Perlroth, who covers cybersecurity for the New York Times and the Bits Blog.","Title: Silver Bullet Talks with Wafaa Mamilli.\nYear: 2018\n\nAbstract: Gary McGraw talks to Wafaa Mamilli is vice president, chief information security officer (CISO) at Eli Lilly and Company, a pharmaceutical company, where she leads a global enterprise-wide information and product security organization.","Title: The New Killer App for Security: Software Inventory.\nYear: 2018\n\nAbstract: Unless you want to be the next data-breach headline, develop and maintain an inventory of all the software, including open source packages, that your organization uses.","Title: Silver Bullet Talks with Craig Froelich.\nYear: 2018\n\nAbstract: Gary McGraw talks to Craig Froelich, the CISO of Bank of America.","Title: Silver Bullet Talks with Bruce Potter.\nYear: 2018\n\nAbstract: Gary McGraw speaks to Bruce Potter, chief information security officer (CISO) at Expel","Title: Silver Bullet Talks with Nick Weaver.\nYear: 2018\n\nAbstract: Gary McGraw speaks with Nick Weaver, staff researcher at Berkeley’s International Computer Science Institute.","Title: Silver Bullet Talks with Tanya Janca.\nYear: 2018\n\nAbstract: Gary McGraw interviews Tanya Janca, senior cloud developer advocate for Microsoft, specializing in software security.","Title: Engineering Security Vulnerability Prevention, Detection, and Response.\nYear: 2018\n\nAbstract: Around the turn of the 21st century, practices began to emerge to guide teams toward engineering software to stop attackers and users from utilizing unintended functionality by violating the system designer's assumptions to cause a security breach. Yet, breaches are reported daily in the news in all domains-from the casual to the critical. The goal of this article is to help software engineers, so...","Title: Silver Bullet Talks With Kathleen Fisher [Interview]\nYear: 2018\n\nAbstract: Kathleen Fisher is a professor in and chair of the Tufts Department of Computer Science. Previously, Dr. Fisher was a program manager at DARPA, where she started and managed High-Assurance Cyber Military Systems (HACMS) and Probabilistic Programming for Advancing Machine Learning (PPAML). She also has been a faculty member at Stanford University and a principal member of the technical staff at AT&T Labs Research. Kathleen's research focuses on advancing the theory and practice of programming languages. Recently, she's been exploring synergies between machine learning and programming languages with an emphasis on building more secure systems."],"string":"[\n \"Title: Software Penetration Testing\\nYear: 2005\\n\\nAbstract: Quality assurance and testing organizations are tasked with the broad objective of assuring that a software application fulfills its functional business requirements. Such testing most often involves running a series of dynamic functional tests, to ensure proper implementation of the applicationýs features. However, because security is not a feature or even a set of features, security testing doesn't directly fit into this paradigm.\",\n \"Title: Software Security Testing\\nYear: 2004\\n\\nAbstract: Security testing has recently moved beyond the realm of network port scanning to include probing-softwareýs behavior as a critical aspect of system behavior. Unfortunately, testing software security is a commonly misunderstood task. Security testing done properly goes deeper than simple black-box probing on the presentation layer (the sort performed by so-called application security tools)-even beyond the functional testing of security apparatuses. Testers must use a risk-based approach, grounded in both the systemýs architectural reality and the attackerýs mindset, to adequately gauge software security. By identifying risks in the system and creating tests driven by those risks, a software security tester can properly focus on those areas of code in which an attack will succeed. This approach provides a higher level of software security assurance than possible with classical black-box testing.\",\n \"Title: Managing Software Security Risks\\nYear: 2002\\n\\nAbstract: Most organizations manage computer security risk reactively by investing in technologies designed to protect against known system vulnerabilities and monitor intrusions as they occur. However, firewalls, cryptography, and antivirus protection address the symptoms, not the root cause, of most security problems. Buying and maintaining a firewall, for example, is ineffective if external users can access remotely exploitable Internet-enabled applications through it. Because hackers attack software, improving computer security depends on proactively managing risks associated with software and software development. The current \\\"penetrate and patch\\\" approach of fixing broken software only after it has been compromised is insufficient to control the problem\",\n \"Title: Guest Editors' Introduction: Securing Online Games: Safeguarding the Future of Software Security\\nYear: 2009\\n\\nAbstract: Massively distributed online role-playing games are a bellwether for problems to come in software security. As cloud computing, service-oriented architecture, and Web 2.0 take off, we can expect to grapple with very similar technical issues to those currently facing online games. The guest editors of this special issue on securing online games tackle this problem from three angles, describing the articles they've lined up to address money and virtual economies, the nascent state of the law, and thorny technical issues.\",\n \"Title: Knowledge for Software Security\\nYear: 2005\\n\\nAbstract: A critical challenge facing software security today is the dearth of experienced practitioners. Approaches that rely solely on apprenticeship as a method of propagation won't scale quickly enough to address this burgeoning problem, so as the field evolves and establishes best practices, knowledge management can play a central role in encapsulating and spreading the emerging discipline more efficiently. This article is about the kinds of security knowledge that can provide a solid foundation for software security practices.\",\n \"Title: Software Assurance for Security\\nYear: 1999\\n\\nAbstract: The article discusses an approach to security analysis that we have applied successfully over the past several years (to 1999) at Reliable Software Technologies. Our approach is no magic bullet, but it offers a reasoned methodology that has proven to be useful in the trenches. Our methodology, like many useful things, is a mix of art and engineering. The idea is straightforward: design a system with security in mind, analyze the system in light of known and anticipated risks, rank the risks according to their severity, test to the risks, and cycle broken systems back through the design process. The process outlined above has one essential underlying goal: avoiding the unfortunately pervasive penetrate-and-patch approach to computer security-that is, avoiding the problem of desperately trying to come up with a fix to a problem that is being actively exploited by attackers. In simple economic terms, finding and removing bugs in a software system before its release is orders of magnitude cheaper and more effective than trying to fix systems after release\",\n \"Title: Static Analysis for Security\\nYear: 2004\\n\\nAbstract: All software projects are guaranteed to have one artifact in common: source code. Together with architectural risk analysis, code review for security ranks very high on the list of software security best practices. Here, we'll look at how to automate source-code security analysis with static analysis tools.\",\n \"Title: Online Games and Security\\nYear: 2007\\n\\nAbstract: Gaming has always been (and remains) a prime driver of PC technology, with deep penetration into the consumer market. Yet, online games -- especially massively multiplayer online role-playing games (MMORPGs) -- suffer from various security problems. This introduction to MMORPG security focuses on bugs involving time and state -- bugs that will likely appear more frequently as real-world software evolves to become more like game software.\",\n \"Title: Statically Scanning Java Code: Finding Security Vulnerabilities\\nYear: 2000\\n\\nAbstract: Developers and users require some degree of assurance in their applications' security vulnerabilities. The authors have designed a prototype tool, Jslint, to help programmers automatically use existing security knowledge.\",\n \"Title: Technology Transfer: A Software Security Marketplace Case Study\\nYear: 2011\\n\\nAbstract: Gary McGraw is one of those astounding people you meet in our industry—a technical wizard who's also a musician (check out Where's Aubrey www.wheresaubrey.com) and a chef. He has, in effect, defined software security with a process that is true science in action (check out the BSIMM at www.cigital.com/services/bsimm/). He's one of the most thought-provoking yet entertaining speakers and writers I know. I'm happy to include his contribution in the Insights series.\",\n \"Title: Wouldn't it be nice to have software labels\\nYear: 2010\\n\\nAbstract: No abstract available.\",\n \"Title: Automated Code Review Tools for Security\\nYear: 2008\\n\\nAbstract: Static analysis identifies many common coding problems automatically, before a program is released.\",\n \"Title: A 'Crystal Ball' for Software Liability\\nYear: 1997\\n\\nAbstract: Software developers are living in a liability grace period, but it won't last. To adequately insure themselves against potential liability, developers need tools to identify worst-case scenarios and help them quantify the risks associated with a piece of software. For assessing such risks associated with software, the authors recommend fault injection, which provides worst-case predictions about how badly a piece of code might behave and how frequently it might behave that way. By contrast, software testing states how good software is. But even correct code can have \\\"bad days,\\\" when external influences keep it from working as desired. Fault injection is arguably the next best thing to having a crystal ball, and it certainly beats facing the future with no predictions at all. It should be a regular part of risk assessment. The greatest benefit from fault injection occurs when a piece of software does not tolerate injected anomalies. False optimism gives way to the only honest claim-that the software presents risks.\",\n \"Title: Silver Bullet Speaks with Ed Felten\\nYear: 2006\\n\\nAbstract: Featured here is an excerpt adapted from the full interview between Felten and Silver Bullet host Gary McGraw. Their conversation ranged widely, from Felten's technology predictions and his thoughts on public policy and law all the way to raising kids.\",\n \"Title: Silver Bullet Speaks with Dorothy Denning\\nYear: 2007\\n\\nAbstract: Gary McGraw speaks with Dorothy Denning in a wide-ranging conversation that covers teaching computer security to the Big Sur Power Walk.\",\n \"Title: Silver Bullet Speaks with Dan Geer\\nYear: 2006\\n\\nAbstract: Dan Geer discusses his work in Project Athena and his thoughts on data security.\",\n \"Title: Silver Bullet Speaks to Avi Rubin\\nYear: 2006\\n\\nAbstract: Avi Rubin discusses his favorite projects, including the SpeedPass hack and electronic voting.\",\n \"Title: Silver Bullet Talks with John Savage\\nYear: 2011\\n\\nAbstract: Gary McGraw interviews John Savage, the An Wang Professor of Computer Science at Brown University. Savage served as a Jefferson Science Fellow in the US Department of State during the 2009–2010 academic year. In his lengthy career, he has held many positions and received several honors for his work in theoretical computer science and computational nanotechnology. His latest book is Models of Computation: Exploring the Power of Computing. Hear the full podcast at www.computer.org/silverbullet or www. cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Jon Swartz\\nYear: 2008\\n\\nAbstract: Silver Bullet host Gary McGraw chats with USA Today reporter, Jon Swartz about security.\",\n \"Title: Silver Bullet Talks with Jeremiah Grossman\\nYear: 2009\\n\\nAbstract: Silver Bullet Security Podcast host Gary McGraw interviews Jeremiah Grossman, founder and CTO of WhiteHat Security, who is well known for his work in Web application security.\",\n \"Title: Silver Bullet Talks with Jon Callas.\\nYear: 2014\\n\\nAbstract: Jon Callas, chief technology officer at Silent Circle, talks to Gary McGraw about the early days of computing, nascent cryptography, Lavabit, Edward Snowden, and software security versus reality. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Kay Connelly\\nYear: 2012\\n\\nAbstract: Gary McGraw interviews Kay Connelly, who, at the time of this interview, is an associate professor of computer science at Indiana University and senior associate director of IU's Center for Applied Cybersecurity Research. She describes why in situ usability study is important, the ETHOS living lab, and her advice to women interested in pursuing a career in computer science. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Halvar Flake\\nYear: 2011\\n\\nAbstract: Gary McGraw interviews Halvar Flake. Before moving over to Google, Halvar Flake ran Zynamics,a company specializing in reverse engineering tools, as an independent researcher and consultant focused on reverse engineering and vulnerability discovery. Flake has spoken at RSA, Black Hat, CanSecWest, and other venues; he has also taught classes on code analysis, reverse engineering, and vulnerability analysis for independent software vendors and governments. Hear the full podcast at www.computer.org/silverbullet or www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Howard Schmidt\\nYear: 2012\\n\\nAbstract: Gary McGraw interviews Howard Schmidt, former cybersecurity coordinator for the Obama administration. They discuss the differences between doing security work in the public and private sectors, the difficulties of establishing cybersecurity in the government, and how the actions of Anonymous and Wikileaks square with the notion of free speech. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Giovanni Vigna\\nYear: 2012\\n\\nAbstract: Gary McGraw interviews Giovanni Vigna, a professor of computer science at the University of California, Santa Barbara, where he works on Web security, vulnerability analysis, malware countermeasures, and intrusion detection. Vigna is also codirector of the UCSB Security Lab and a member of the Shellphish and Epic Fail hacker collectives. He cofounded Lastline (an antimalware company) and organizes the annual International Capture the Flag hacking competition (iCTF). Hear the full podcast series at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Gary Warzala\\nYear: 2013\\n\\nAbstract: Gary McGraw interviews Gary Warzala, Visa's chief information security officer. He talks about the daily life of a CISO, how companies can attract and retain good security employees, and how to measure security and discuss the results with management. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Iván Arce\\nYear: 2010\\n\\nAbstract: Silver Bullet Security Podcast host Gary McGraw interviews Iván Arce, chief technology officer of Core Security Technologies.\",\n \"Title: Silver Bullet Talks with Fred Schneider\\nYear: 2009\\n\\nAbstract: Gary McGraw talks with associate editor in chief of S&P Fred Schneider of Cornell University about security and reliability, trust, and diversity in software systems.\",\n \"Title: Silver Bullet Talks with Gunnar Peterson\\nYear: 2009\\n\\nAbstract: Gary McGraw interviews Gunnar Peterson, a software security expert and a managing principal at Arctec Group, a Minneapolis-based consulting firm. His work centers around service-oriented architecture (SOA), Web 2.0, and other distributed systems. Peterson's blog, http://1raindrop.typepad.com, is devoted to topics in software security. He also edits IEEE Security & Privacy magazine's Building Security In column with John Stevens from Cigital and Deborah Frincke..\",\n \"Title: Silver Bullet Talks with Greg Morrisett\\nYear: 2010\\n\\nAbstract: Gary McGraw interviews Greg Morrisett, the Allen B. Cutting Professor of Computer Science and associate dean for computer science and engineering at Harvard University. His current work is on applications of advanced type systems, model checkers, proof-carrying code, and inline reference monitors for building efficient and provably secure systems. He's also working on languages for sensor networks. Hear the full podcast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is the full transcript of the interview.\",\n \"Title: Silver Bullet Talks with Gillian Hayes\\nYear: 2010\\n\\nAbstract: Gary Mc Graw interviews Gillian Hayes. She is an assistant professor in Informatics at the Bren School of Information and Computer Sciences at University of California, Irvine (UCI). She's director of the Social and Technological Action Research Group, otherwise known as \\\"STAR.\\\" Hear the full podcast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is the full transcript of the interview.\",\n \"Title: Silver Bullet Talks with Elinor Mills\\nYear: 2011\\n\\nAbstract: Gary McGraw talks with Elinor Mills, a senior writer at CNET (www.news.com), where she covers Internet technology and security. She has written about technology for several outlets over the past 20 years, including Reuters, the Associated Press, the Industry Standard, and IDG. The 2010 Apollo Research Security Survey placed Mills at the top of its list of journalists who reach the largest audience when writing about security. Hear the full podcast at www.computer.org/silverbullet or www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Ed Amoroso\\nYear: 2008\\n\\nAbstract: Gary McGraw interviews Ed Amoroso, AT&T's chief information security officer. Their conversation ranged widely, from system design to privacy.\",\n \"Title: Silver Bullet Talks with David Rice\\nYear: 2011\\n\\nAbstract: Gary McGraw interviews David Rice, formerly the executive director of The Monterey Group, a strategic consulting firm that focuses its services on cybersecurity and identity management. Now the director of global security at Apple, Rice has also served as a global network vulnerability analyst for the US National Security Agency and was a special duty cryptologic officer for the US Navy. Rice wrote Geekonomics: The Real Cost of Insecure Software (Addison-Wesley, 2007) and speaks at many events around the world. Hear the full podcast at www.computer.org/silverbullet or www. cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Adam Shostack\\nYear: 2008\\n\\nAbstract: Gary McGraw interviews Adam Shostack. Shostack is a member of Microsoft's Secure Development Lifecycle Team. He's worked for Zero Knowledge as Most Evil Genius and Reflective where, as CTO, he focused on static analysis for software security. Shostack recently coauthored The New School of Information Security with Andrew Stewart.\",\n \"Title: Silver Bullet Talks with Becky Bace\\nYear: 2007\\n\\nAbstract: Gary McGraw speaks with Becky Bace. Their conversation ranged widely, from explosives to vulnerability disclosure to venture capital.\",\n \"Title: Silver Bullet Talks with Christofer Hoff\\nYear: 2010\\n\\nAbstract: Gary McGraw interviews Christofer Hoff, the director of cloud and virtualizations solutions at Cisco. He has also been a chief security architect at Unisys, a chief architect, a CSO, and a CTO. Hoff has a well-trafficked blog at www.rationalsurvivability.com/blog. The Web extra includes the full interview. The audio interview is available here: www.computer.org/security/silverbullet/.\",\n \"Title: Silver Bullet Talks with Annie Antón\\nYear: 2007\\n\\nAbstract: Gary McGraw interviews Annie Antón.\",\n \"Title: Silver Bullet Talks with Wenyuan Xu\\nYear: 2013\\n\\nAbstract: Wenyuan Xu, as associate professor at the University of South Carolina, talks about the differences between American and Chinese technical culture, her work on automatic meter reading systems, whether electrical engineering is more advanced in terms of design than computer science, and why there are so few women in engineering and computer science. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Virgil Gligor\\nYear: 2009\\n\\nAbstract: Gary McGraw interviews Virgil Gligor, a professor in Carnegie Mellon University's (CMU) Department of Electrical and Computer Engineering. He's also codirector of CyLab (www.cylab.cmu.edu). Gligor serves on Microsoft's Trusted Computing Academic Advisory Board and has consulted with Burroughs and IBM. Gligor has served on many government information security study groups and served on the National Research Council's Panel on Information Security.\",\n \"Title: Silver Bullet talks with Thomas Rid\\nYear: 2013\\n\\nAbstract: Gary McGraw interviews Thomas Rid, a Reader in War Studies at King's College London. Rid discusses how his life as a \\\"wandering academic\\\" influences his work, cyberwar, military dictionaries, and the problem of jargon. Rid has worked as a visiting scholar in Jerusalem, at the Wilson Center, at RAND, and at the Institut Fran&amp;#x00E7;ais de Relation International in Paris. He has PhD in political science from Humboldt University of Berlin; his books include Understanding Counterinsurgency, War 2.0, War and Media Operations. His new book, Cyber War Will Not Take Place, is out in the US with Oxford University Press in September 2013. He lives in London with his wife. The full podcast is at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Steve Bellovin\\nYear: 2013\\n\\nAbstract: Gary McGraw interviews Steve Bellovin, professor of computer science at Columbia University and CTO of the Federal Trade Commission. They discuss technology transfer, how code has gotten better but the threat model has changed, whether mobile security is just a repackaging of the same security problem, the very first days of Usenet, and the famed Evil Bit. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Richard Clarke\\nYear: 2010\\n\\nAbstract: Gary McGraw interviews Richard A. Clarke. Clarke is an internationally recognized expert on national security, counter terrorism, and cyber security. He's an on-air consultant for ABC news and teaches at the Kennedy School of Government. Clarke served for 11 consecutive years in the White House for three different presidents, including a stint as special advisor to the president for cybersecurity. Before his work in the White House, he worked in the Pentagon, the intelligence community, and the State Department. He's the author of a number of books, including Against All Enemies and his new book Cyber War (which is orange). Hear the full podcast or watch the videocast of the interview at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/. The Web extra is a full transcript of the interview.\",\n \"Title: Silver Bullet Talks with Ross Anderson\\nYear: 2007\\n\\nAbstract: Gary McGraw chats with Ross Anderson, professor of security engineering at the Computer Laboratory at Cambridge University and author of Security Engineering. Gary and Ross discuss the simple reasons why most systems fail, the economic imbalance between engineers/developers and a system's users, and why publicly describing attacks is essential to security engineering.\",\n \"Title: Silver Bullet Talks with Ralph Langner\\nYear: 2011\\n\\nAbstract: Gary McGraw interviews Ralph Langner, the founder and CEO of Langner Communications, a German company focused on control system security. He has more than 20 years' experience working with computerized control systems and was the first researcher to determine that Stuxnet was a directed cyberattack against Iran. Hear the full podcast at www.computer.org/security/podcasts or www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Randy Sabett\\nYear: 2012\\n\\nAbstract: Gary McGraw talks to Randy Sabett, a lawyer with the ZwillGen cyberlaw firm in Washington, DC, about cybercrime and the law. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Paul Kocher\\nYear: 2011\\n\\nAbstract: Gary McGraw interviews Paul Kocher, president and chief scientist of Cryptography Research. Among his many accomplishments, he helped design SSL 3.0, Electronic Frontier Foundation's DES cracker (nicknamed \\\"Deep Crack\\\"), and parts of the content security system found on Blu-ray discs. He continues to design crypto protocols and applications, which are then successfully deployed in real-world systems. Hear the full podcast at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet. The Web extra is a full transcript of the interview.\",\n \"Title: Silver Bullet Talks with Neil Daswani\\nYear: 2012\\n\\nAbstract: Gary McGraw interviews Neil Daswani, a manager in Twitter's revenue engineering team. He was formerly the CTO and cofounder of Dasient, an Internet security company that Twitter purchased in January 2012.\",\n \"Title: Silver Bullet Talks with Matthew Green.\\nYear: 2014\\n\\nAbstract: Matthew Green, an assistant research professor at Johns Hopkins Information Security Institute, talks about the difference between theoretical and applied cryptography, blogs, and back doors.\",\n \"Title: Silver Bullet Talks with Matt Bishop\\nYear: 2008\\n\\nAbstract: Gary McGraw interviews Matt Bishop, who has made significant inroads in the commercial side of security, lecturing for the SANS Institute, and focusing much of his writing on security education. He is the author of Computer Security: Art and Science (Addison-Wesley, 2002), an important textbook in the space. You can find additional podcasts in the series at www.computer.org/security/podcasts/ or www.cigital.com/silverbullet/.\",\n \"Title: Lost Decade or Golden Era: Computer Security since 9/11\\nYear: 2012\\n\\nAbstract: In the 10 years since 9/11, the cybersecurity threat has evolved significantly, and every sector of the US economy has become more dependent than ever on the Internet. Today, major security breaches dominate headlines on a weekly basis. Intrusion campaigns such as \\\"Operation Shady Rat\\\" (disclosed by McAfee in August) and \\\"Nitro\\\" (disclosed by Symantec in October) show a systematic compromise of every significant sector of the economy, including technology, industrial manufacturing, defense, financial services, and government and nongovernmental organizations. In addition to the systematic compromises of these sectors, we've also seen hints and speculation of cyberwarfare operations including Stuxnet, Duqu, and the recent loss and capture of the US RQ-170 Sentinel spy drone over Iran. But over the same 10-year time period, security technology has arguably improved incrementally, with innovation occurring in some areas. The question the authors attempt to address in this point/counterpoint article is whether we're better off today in security than we were 10 years ago.\",\n \"Title: Processes for Producing Secure Software: Summary of US National Cybersecurity Summit Subgroup Report\\nYear: 2004\\n\\nAbstract: This report summarizes work initiated at the National Cybersecurity Summit, held 2-3 December 2003 in Santa Clara, California. Attendees representing industry, academia, and the US Department of Homeland Security (DHS) formed five task forces to focus on specific topic areas. This report describes the key problems and recommendations identified by the Software Process subgroup of the \\\"Security across the Software Development Lifecycle\\\" task force.\",\n \"Title: Token-based scanning of source code for security problems\\nYear: 2002\\n\\nAbstract: We describe ITS4, a tool for statically scanning C and C++ source code for security vulnerabilities. Compared to other approaches, our scanning technique stakes out a new middle ground between accuracy and efficiency. This method is efficient enough to offer real-time feedback to developers during coding while producing few false negatives. Unlike other techniques, our method is also simple enough to scan C++ code despite the complexities inherent in the language. Using ITS4, we found new remotely exploitable vulnerabilities in a widely distributed software package as well as in a major piece of e-commerce software.We also describe functionality in more recent tools modeled after ITS4, and discuss algorithms that could easily be used to augment these kinds of tools. Particularly, we describe a solution we have prototyped that allows for more rigorous analysis of C and C++ source code, without failing to analyze parts of the program due to preprocessor conditionals.\",\n \"Title: Will Openish Source Really Improve Security\\nYear: 2000\\n\\nAbstract: Will openish source really improve security? No.\",\n \"Title: Security as a new dimension in embedded system design\\nYear: 2004\\n\\nAbstract: The growing number of instances of breaches in information security in the last few years has created a compelling case for efforts towards secure electronic systems. Embedded systems, which will be ubiquitously used to capture, store, manipulate, and access data of a sensitive nature, pose several unique and interesting security challenges. Security has been the subject of intensive research in the areas of cryptography, computing, and networking. However, despite these efforts, security is often mis-construed by designers as the hardware or software implementation of specific cryptographic algorithms and security protocols. In reality, it is an entirely new metric that designers should consider throughout the design process, along with other metrics such as cost, performance, and power..This paper is intended to introduce embedded system designers and design tool developers to the challenges involved in designing secure embedded systems. We attempt to provide a unified and holistic view of embedded system security by first analyzing the typical functional security requirements for embedded systems from an end-user perspective. We then identify the implied challenges for embedded system architects, as well as hardware and software designers (e.g., tamper-resistant embedded system design, processing requirements for security, impact of security on battery life for battery-powered systems, etc.). We also survey solution techniques to address these challenges, drawing from both current practice and emerging research, and identify open research problems that will require innovations in embedded system architecture and design methodologies.\",\n \"Title: Interview: Software Security in the Real World\\nYear: 2010\\n\\nAbstract: In an interview conducted by Computer editorial board member Ann E.K. Sobel, Cigital CTO Gary McGraw discusses the state of software security and the BSIMM—a data-driven research project describing and measuring what successful organizations are doing to ensure software security.\",\n \"Title: Letter Spirit: An Architecture for Creativity in an Microdomain\\nYear: 1993\\n\\nAbstract: The Letter Spirit project explores the creative act of artistic letter-design. The aim is to model how the 26 lowercase letters of the roman alphabet can be rendered in many different but internally coherent styles. Viewed from a distance, the behavior of the program can be seen to result from the interaction of four emergent agents working together to form a coherent style and to design a complete alphabet: the Imaginer (which plays with the concepts behind letterforms), the Drafter (which converts ideas for letterforms into graphical realizations), the Examiner (which combines bottom-up and top-down processing to perceive and categorize letterforms), and the Adjudicator (which perceives and dynamically builds a representation of the evolving style). Creating a gridfont is an iterative process of guesswork and evaluation carried out by the four agents. This process is the central feedback loop of creativity. Implementation of Letter Spirit is just beginning. This paper outlines our goals and plans for the project.\",\n \"Title: Silver Bullet Talks with Per-Olof Persson\\nYear: 2013\\n\\nAbstract: Gary McGraw interviews Per-Olof Persson, currently head of global software security operations at Sony Mobile. Persson discusses the importance of working in different positions within the same company—from directing the Sony Board to running in front of Android phones. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with W. Hord Tipton\\nYear: 2013\\n\\nAbstract: Gary McGraw talks with W. Hord Tipton, executive director of (ISC)2, about how he got into science and engineering, the insights he's cultivated from being a nuclear and chemical engineer, whether or not certification can help advance software security, and the benefits of teaching software security to kids. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Attacking Malicious Code: A Report to the Infosec Research Council\\nYear: 2000\\n\\nAbstract: The accelerating trends of interconnectedness, complexity, and extensibility are aggravating the already-serious threat posed by malicious code. To combat malicious code, these authors argue for creating sound policy about software behavior and enforcing that policy through technological means.\",\n \"Title: Bridging the Gap between Software Development and Information Security\\nYear: 2005\\n\\nAbstract: Traditionally, software development efforts in large corporations have been about as far removed from information security as they were from human resources or any other business function. The disconnect between security and development has ultimately produced software development efforts that lack any sort of contemporary understanding of technical security risks. Today's complex and highly connected computing environments trigger myriad security concerns, so by blowing off the idea of security entirely, software builders virtually guarantee that their creations will have way too many security weaknesses that could--and should--have been avoided. This article presents some recommendations for solving this problem.\",\n \"Title: Predicting How Badly \\\"Good\\\" Software Can Behave\\nYear: 1997\\n\\nAbstract: This paper presents a fault-injection methodology that predicts how software will behave when: (1) componentsof the software fail, (2) hardware components external to the software fail, (3) human factor errorsoccur and bad input is provided to the software, and (4) the software is executing in unlikely operationalmodes. Because of the enterprise-critical nature of many of today's software systems, it is vital that thesesystem are robust enough to handle problems that originate externally as ...\",\n \"Title: Silver Bullet Talks with Brian Krebs\\nYear: 2015\\n\\nAbstract: Gary McGraw talks to Brian Krebs of KrebsOnSecurity.com about security breaches, malware, cybercrime, and getting the general public more involved in cybersecurity.\",\n \"Title: Silver Bullet Talks with Yoshi Kohno.\\nYear: 2014\\n\\nAbstract: nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull...\",\n \"Title: Silver Bullet Talks with the IEEE Center for Secure Design.\\nYear: 2014\\n\\nAbstract: The IEEE Center for Secure Design (CSD), which launched in August 2014, gathers software security expertise from industry, academia, and government and provides guidance on recognizing design flaws and building security in. Three of the founding members of the CSD discuss the project and its future. Hear the full podcast at www.computer.org/silverbullet. Show links, notes, and an online discussion can be found at www.cigital.com/silverbullet.\",\n \"Title: Silver Bullet Talks with Whitfield Diffie\\nYear: 2015\\n\\nAbstract: Gary McGraw talks to Whitfield Diffie, co-creator of the Diffie-Hellman public-key exchange method, about his career in cryptography and the future of privacy.\",\n \"Title: Privacy and security in a networked world\\nYear: 2014\\n\\nAbstract: As news stories continue to demonstrate, ensuring adequate security and privacy in a networked \\\\\\\"always on\\\\\\\" world is a challenge; and while open source software can mitigate problems, it is not a panacea. This panel will bring together experts from industry and academia to debate, discuss, and offer opinions -- questions might include: What are the \\\\\\\"costs\\\\\\\" of \\\\\\\"good enough\\\\\\\" security and privacy on developers and customers? What is the appropriate trade-off between the price provide security and cost of poor security? How can the consequences of poor design and implementation be managed? Can systems be enabled to fail \\\\\\\"security-safe\\\\\\\"? What are the trade-offs for increased adoption of privacy and security best practices? How can the \\\\\\\"costs\\\\\\\" of privacy and security -- both tangible and intangible -- be reduced?\",\n \"Title: Security Fatigue? Shift Your Paradigm\\nYear: 2014\\n\\nAbstract: Software security is the fastest growing paradigm in the IT security field, and the Building Security in Maturity Model (BSIMM) project offers real-world measurements for assessment.\",\n \"Title: From the ground up: the DIMACS software security workshop\\nYear: 2003\\n\\nAbstract: The recent DIMACS Software Security Workshop explored issues such as security engineering, architecture and implementation risks, security analysis, mobile and malicious code, education and training, and open research issues. Many promising techniques have grown from connections between computer security, programming languages, and software engineering, and one workshop goal was to bring these communities closer together to crystallize the software security subfield. The author reports the workshop's results in this article.\",\n \"Title: Guest Editors' Introduction: Why Attacking Systems Is a Good Idea\\nYear: 2004\\n\\nAbstract: The articles in this issue represent the broad range of ideas that come to mind when scientists and engineers think about attacking systems. Some approach the problem by describing technically sophisticated attacks, attack patterns, and toolkits. Others fret about the politics of security and attacks, worrying that outlawing certain kinds of software will backfire. Some describe methodologies for breaking systems (on purpose) in order to evaluate them. Others describe in gory detail the kinds of tools the adversary regularly wields. All of these approaches are useful.\",\n \"Title: Adopting a software security improvement program\\nYear: 2005\\n\\nAbstract: Leading software shops (including Microsoft) are working hard to improve the way they build security into their products. Software security initiatives have proven beneficial for those organizations that have implemented them. Such initiatives involve the adoption and rollout of various types of best practices. The article describes an approach that works, with an emphasis on business process engineering that might be unfamiliar to technical practitioners. By following some commonsense steps, a software security improvement program has a greater chance of achieving its ultimate goal: software security that makes business sense.\",\n \"Title: Software security and SOA: danger, Will Robinson!\\nYear: 2006\\n\\nAbstract: The current buzzword of choice among the technical elite (at least those subject to marketing departments) is service-oriented architecture, or SOA (pronounced 'SO-uh'). As SOA moves from hype to practice, an opportunity exists to do security right, but a similar opportunity exists for disaster if security is done wrong. This article describes 13 snares that we must avoid to end up with SOA security that makes sense.\",\n \"Title: Interview: Silver Bullet Speaks to Marcus Ranum\\nYear: 2006\\n\\nAbstract: In the third episode of the Silver Bullet Security Podcast, Gary talks with Marcus Ranum, who is an acclaimed security guru widely credited with inventing the proxy firewall. Marcus and Gary discuss why Marcus thinks we're not making progress in the computer security field, how common sense would help computer security, and Richard Feynman.\",\n \"Title: Silver Bullet Talks with Steven Kent\\nYear: 2010\\n\\nAbstract: Steven Kent is Chief Scientist for Information Security at BBN Technology, a division of Raytheon, where he's been engaged in network security research and development for several decades. Kent is a wellknown security researcher who's work ranges from end-to-end encryption and access control systems for packet networks, through design of secure transport later and electronic message protocols, to performance analysis of security mechanisms.\",\n \"Title: Four Software Security Findings\\nYear: 2016\\n\\nAbstract: Analyzing data from 78 firms using the Building Security In Maturity Model (BSIMM) revealed four truths about software security that will help firms protect and secure their assets.\",\n \"Title: Silver Bullet Talks with L. Jean Camp\\nYear: 2015\\n\\nAbstract: Gary McGraw talks to L. Jean Camp about translucent security; risk management; and security-related issues affecting usability, economics, and senior citizens.\",\n \"Title: Silver Bullet Talks with Steven M. Bellovin and Matthew Green\\nYear: 2015\\n\\nAbstract: Gary McGraw sits down with security gurus Steven M. Bellovin and Matthew Green, coauthors of the report \\\"Keys under Doormats: Mandating Insecurity by Requiring Government Access to All Data and Communications.\\\"\",\n \"Title: Silver Bullet Talks with Peiter (Mudge) Zatko.\\nYear: 2016\\n\\nAbstract: Gary McGraw interviews Peiter Zatko, known in the security community as Mudge, about the origins of the L0pht hacker collective, managing cybersecurity projects for DARPA, and much more.\",\n \"Title: Silver Bullet Talks with Bart Preneel\\nYear: 2015\\n\\nAbstract: Gary McGraw discusses cryptology and information security with Bart Preneel, a professor at one of the world's oldest universities.\",\n \"Title: Silver Bullet Talks with Jamie Butler.\\nYear: 2016\\n\\nAbstract: Gary McGraw talks to Jamie Butler, the chief technology officer and chief scientist at Endgame, about attacking back, rootkits, OS security, and more.\",\n \"Title: Silver Bullet Talks with Katie Moussouris\\nYear: 2015\\n\\nAbstract: Gary McGraw sits down with HackerOne chief policy officer Katie Moussouris to talk about bug bounties and vulnerability disclosures.\",\n \"Title: Silver Bullet Talks with Jacob West.\\nYear: 2016\\n\\nAbstract: Gary McGraw talks to Jacob West--chief architect for security products at NetSuite--about secure design, the critical difference between bugs and flaws, and wearable device security.\",\n \"Title: Silver Bullet Talks with Martin Hellman.\\nYear: 2016\\n\\nAbstract: Gary McGraw talks to the co-inventor of public-key cryptography, Martin Hellman, about his cutting-edge career, his involvement in the Crypto Wars, and his work with risk management and peace issues.\",\n \"Title: Silver Bullet Talks with Jim Manico.\\nYear: 2016\\n\\nAbstract: Gary McGraw sits down with Jim Manico of Manicode Security about static analysis, open source, and developer training.\",\n \"Title: Silver Bullet Talks with Marie Moe.\\nYear: 2017\\n\\nAbstract: Gary McGraw sits down with Marie Moe, a SINTEF research scientist and associate professor at the Norwegian University of Science and Technology, to talk about medical device security.\",\n \"Title: Six Tech Trends Impacting Software Security.\\nYear: 2017\\n\\nAbstract: The past few years have seen radical shifts in the way software is developed, in terms of both process and the technology stack. We must actively track these changes to ensure that software security solutions remain relevant.\",\n \"Title: Silver Bullet Talks with Lesley Carhart.\\nYear: 2017\\n\\nAbstract: Gary McGraw talks to Lesley Carhart about the information security community, digital forensics and incident response, future hackers, and more.\",\n \"Title: Silver Bullet Talks with Kate Pearce.\\nYear: 2017\\n\\nAbstract: Gary McGraw talks to Kate Pearce about the state of the software security industry, gender perspectives in the security space, the relationship between biology and security, and more.\",\n \"Title: Silver Bullet Talks with Kelly Lum.\\nYear: 2017\\n\\nAbstract: Gary McGraw talks to Kelly Lum about security engineering and her work at Tumblr.\",\n \"Title: Silver Bullet Talks with Ksenia Dmitrieva-Peguero.\\nYear: 2017\\n\\nAbstract: Gary McGraw talks to Synopsys’s Ksenia Dmitrieva-Peguero about software security awareness, the benefits and drawbacks of frameworks like AngularJS, her favorite security conferences, and more.\",\n \"Title: Silver Bullet Talks with Nicole Perlroth.\\nYear: 2017\\n\\nAbstract: Gary McGraw talks to Nicole Perlroth, who covers cybersecurity for the New York Times and the Bits Blog.\",\n \"Title: Silver Bullet Talks with Wafaa Mamilli.\\nYear: 2018\\n\\nAbstract: Gary McGraw talks to Wafaa Mamilli is vice president, chief information security officer (CISO) at Eli Lilly and Company, a pharmaceutical company, where she leads a global enterprise-wide information and product security organization.\",\n \"Title: The New Killer App for Security: Software Inventory.\\nYear: 2018\\n\\nAbstract: Unless you want to be the next data-breach headline, develop and maintain an inventory of all the software, including open source packages, that your organization uses.\",\n \"Title: Silver Bullet Talks with Craig Froelich.\\nYear: 2018\\n\\nAbstract: Gary McGraw talks to Craig Froelich, the CISO of Bank of America.\",\n \"Title: Silver Bullet Talks with Bruce Potter.\\nYear: 2018\\n\\nAbstract: Gary McGraw speaks to Bruce Potter, chief information security officer (CISO) at Expel\",\n \"Title: Silver Bullet Talks with Nick Weaver.\\nYear: 2018\\n\\nAbstract: Gary McGraw speaks with Nick Weaver, staff researcher at Berkeley’s International Computer Science Institute.\",\n \"Title: Silver Bullet Talks with Tanya Janca.\\nYear: 2018\\n\\nAbstract: Gary McGraw interviews Tanya Janca, senior cloud developer advocate for Microsoft, specializing in software security.\",\n \"Title: Engineering Security Vulnerability Prevention, Detection, and Response.\\nYear: 2018\\n\\nAbstract: Around the turn of the 21st century, practices began to emerge to guide teams toward engineering software to stop attackers and users from utilizing unintended functionality by violating the system designer's assumptions to cause a security breach. Yet, breaches are reported daily in the news in all domains-from the casual to the critical. The goal of this article is to help software engineers, so...\",\n \"Title: Silver Bullet Talks With Kathleen Fisher [Interview]\\nYear: 2018\\n\\nAbstract: Kathleen Fisher is a professor in and chair of the Tufts Department of Computer Science. Previously, Dr. Fisher was a program manager at DARPA, where she started and managed High-Assurance Cyber Military Systems (HACMS) and Probabilistic Programming for Advancing Machine Learning (PPAML). She also has been a faculty member at Stanford University and a principal member of the technical staff at AT&T Labs Research. Kathleen's research focuses on advancing the theory and practice of programming languages. Recently, she's been exploring synergies between machine learning and programming languages with an emphasis on building more secure systems.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":99,"string":"99"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":50,"string":"50"}}},{"rowIdx":51,"cells":{"question_id":{"kind":"string","value":"Sanming Zhou"},"question":{"kind":"string","value":"Generate an abstract for the title \"Finite symmetric graphs with two-arc transitive quotients II\" using the following items: finite G-symmetric graph, G-invariant partition, (G, 2)-arc transitive, 2-designs, Steinersystem."},"answer":{"kind":"string","value":"Let Γ be a finite G-symmetric graph whosevertex set admits a nontrivial G-invariant partitionB. It was observed that the quotient graphΓB of Γ relative toB can be (G, 2)-arc transitive even ifΓ itself is not necessarily (G, 2)-arctransitive. In a previous article of Iranmanesh et al., thisobservation motivated a study of G-symmetric graphs(Γ,B) such that ΓB is(G, 2)-arc transitive and, for blocks B,C εB adjacent inΓB, there are exactly |B| - 2(≥1)vertices in B which have neighbors in C. In thepresent article we investigate the general case whereΓB is (G, 2)-arc transitive and isnot multicovered by Γ (i.e., at least one vertex inB has no neighbor in C for adjacent B, CεB) by analyzing the dual D*(B)of the 1-designD(B):=(B,ΓB(B),I),where ΓB(B) is theneighborhood of B in ΓB andαIC (α ε B, C εΓB(B)* inD(B) if and only if α has at leastone neighbor in C. In this case, a crucial feature is thatD*(B) admits G as a group of automorphismsacting 2-transitively on points and transitively on blocks andflags. It is proved that the case when no point ofD(B) is incident with two blocks can be reduced tomulticovers, and the case when no point of D(B) is incident withtwo blocks can be partially reduced to the 3-arc graphconstruction, where D(B) is the complementof D(B). In the general situation, bothD*(B) and its complement D* are (G,2)-point-transitive and G-block-transitive 2-designs, andexploring relationships between them and Γ is anattractive research direction. In the article we investigate thedegenerate case where D*(B) or D* is a trivial Steinersystem with block size 2, that is, a complete graph. In each ofthese cases, we give a construction which produces symmetric graphswith the corresponding properties, and we prove further that everysuch graph Γ can be constructed fromΓB by using the construction. © 2007Wiley Periodicals, Inc. J Graph Theory 56: 167193, 2007"},"correct_answer":{"kind":"string","value":"Let Γ be a finite G-symmetric graph whosevertex set admits a nontrivial G-invariant partitionB. It was observed that the quotient graphΓB of Γ relative toB can be (G, 2)-arc transitive even ifΓ itself is not necessarily (G, 2)-arctransitive. In a previous article of Iranmanesh et al., thisobservation motivated a study of G-symmetric graphs(Γ,B) such that ΓB is(G, 2)-arc transitive and, for blocks B,C εB adjacent inΓB, there are exactly |B| - 2(≥1)vertices in B which have neighbors in C. In thepresent article we investigate the general case whereΓB is (G, 2)-arc transitive and isnot multicovered by Γ (i.e., at least one vertex inB has no neighbor in C for adjacent B, CεB) by analyzing the dual D*(B)of the 1-designD(B):=(B,ΓB(B),I),where ΓB(B) is theneighborhood of B in ΓB andαIC (α ε B, C εΓB(B)* inD(B) if and only if α has at leastone neighbor in C. In this case, a crucial feature is thatD*(B) admits G as a group of automorphismsacting 2-transitively on points and transitively on blocks andflags. It is proved that the case when no point ofD(B) is incident with two blocks can be reduced tomulticovers, and the case when no point of D(B) is incident withtwo blocks can be partially reduced to the 3-arc graphconstruction, where D(B) is the complementof D(B). In the general situation, bothD*(B) and its complement D* are (G,2)-point-transitive and G-block-transitive 2-designs, andexploring relationships between them and Γ is anattractive research direction. In the article we investigate thedegenerate case where D*(B) or D* is a trivial Steinersystem with block size 2, that is, a complete graph. In each ofthese cases, we give a construction which produces symmetric graphswith the corresponding properties, and we prove further that everysuch graph Γ can be constructed fromΓB by using the construction. © 2007Wiley Periodicals, Inc. J Graph Theory 56: 167193, 2007"},"documents":{"kind":"list like","value":["Title: Unitary Graphs.\nYear: 2014\n\nAbstract: Unitary graphs are arc-transitive graphs with vertices the flags of Hermitian unitals and edges defined by certain elements of the underlying finite fields. They played a significant role in a recent classification of a class of arc-transitive graphs that admit an automorphism group acting imprimitively on the vertices. In this paper we prove that all unitary graphs are connected of diameter two and girth three. Based on this we obtain, for any prime power $q > 2$, a lower bound of order $O(\\Delta^{5/3})$ on the maximum number of vertices in an arc-transitive graph of degree $\\Delta = q(q^2-1)$ and diameter two.","Title: Rotational circulant graphs\nYear: 2014\n\nAbstract: A Frobenius group is a transitive permutation group which is not regular but only the identity element can fix two points. Such a group can be expressed as the semidirect product G = K ¿ H of a nilpotent normal subgroup K and another group H fixing a point. A first-kind G -Frobenius graph is a connected Cayley graph on K with connection set an H -orbit a H on K that generates K , where H has an even order or a is an involution. It is known that the first-kind Frobenius graphs admit attractive routing and gossiping algorithms. A complete rotation in a Cayley graph on a group G with connection set S is an automorphism of G fixing S setwise and permuting the elements of S cyclically. It is known that if the fixed-point set of such a complete rotation is an independent set and not a vertex-cut, then the gossiping time of the Cayley graph (under a certain model) attains the smallest possible value. In this paper we classify all first-kind Frobenius circulant graphs that admit complete rotations, and describe a means to construct them. This result can be stated as a necessary and sufficient condition for a first-kind Frobenius circulant to be 2-cell embeddable on a closed orientable surface as a balanced regular Cayley map. We construct a family of non-Frobenius circulants admitting complete rotations such that the corresponding fixed-point sets are independent and not vertex-cuts. We also give an infinite family of counterexamples to the conjecture that the fixed-point set of every complete rotation of a Cayley graph is not a vertex-cut.","Title: A Class of Arc-Transitive Cayley Graphs as Models for Interconnection Networks\nYear: 2009\n\nAbstract: We study a class of Cayley graphs as models for interconnection networks. With focus on efficient communication we prove that for any graph in the class there exists a gossiping protocol which exhibits attractive features, and, moreover, we give an algorithm for constructing such a protocol. In particular, these hold for two important subclasses of graphs, namely, Cayley graphs admitting a complete rotation and Frobenius graphs of a certain type. For such Frobenius graphs, we obtain the minimum gossip time and give an optimal gossiping protocol under which messages are transmitted along shortest paths and each arc is used exactly once at each time step. Moreover, for such Frobenius graphs we construct an all-to-all shortest path routing that is arc-transitive, edge- and arc-uniform, and optimal for the edge- and arc-forwarding indices simultaneously.","Title: Frobenius circulant graphs of valency six, Eisenstein-Jacobi networks, and hexagonal meshes\nYear: 2014\n\nAbstract: A Frobenius group is a transitive but not regular permutation group such that only the identity element can fix two points. A finite Frobenius group can be expressed as G=K@?H with K a nilpotent normal subgroup. A first-kind G-Frobenius graph is a Cayley graph on K with connection set S an H-orbit on K generating K, where H is of even order or S consists of involutions. We classify all 6-valent first-kind Frobenius circulant graphs such that the underlying kernel K is cyclic. We give optimal gossiping and routing algorithms for such a circulant and compute its forwarding indices, Wiener indices and minimum gossip time. We also prove that its broadcasting time is equal to its diameter plus two or three. We prove that all 6-valent first-kind Frobenius circulants with cyclic kernels are Eisenstein-Jacobi graphs, the latter being Cayley graphs on quotient rings of the ring of Eisenstein-Jacobi integers. We also prove that larger Eisenstein-Jacobi graphs can be constructed from smaller ones as topological covers, and a similar result holds for 6-valent first-kind Frobenius circulants. As a corollary any Eisenstein-Jacobi graph with order congruent to 1 modulo 6 and underlying Eisenstein-Jacobi integer not an associate of a real integer, is a cover of a 6-valent first-kind Frobenius circulant. A distributed real-time computing architecture known as HARTS or hexagonal mesh is a special 6-valent first-kind Frobenius circulant.","Title: Finite locally-quasiprimitive graphs\nYear: 2002\n\nAbstract: A finite graph is said to be locally-quasiprimitive relative to a subgroup G of automorphisms if, for all vertices α, the stabiliser in G of α is quasiprimitive on the set of vertices adjacent to α. (A permutation group is said to be quasiprimitive if all of its non-trivial normal subgroups are transitive.) The graph theoretic condition of local quasiprimitivity is strictly weaker than the conditions of local primitivity and 2-arc transitivity which have been studied previously. It is shown that the family of locally-quasiprimitive graphs is closed under the formation of a certain kind of quotient graph, called a normal quotient, induced by a normal subgroup. Moreover, a locally-quasiprimitive graph is proved to be a multicover of each of its normal quotients. Thus finite locally-quasiprimitive graphs which are minimal in the sense that they have no non-trivial proper normal quotients form an important sub-family, since each finite locally-quasiprimitive graph has at least one such graph as a normal quotient. These minimal graphs in the family are called \"basic\" locally-quasiprimitive graphs, and their structure is analysed. The process of constructing locally-quasiprimitive graphs with a given locally-quasiprimitive graph Σ as a normal quotient is then considered. It turns out that this can be viewed as a problem of constructing covering graphs of certain multigraphs associated with Σ. Further, it is shown that, under certain conditions, a locally-quasiprimitive graph can be reconstructed from knowledge of two of its normal quotients. Finally a series of open problems is presented.","Title: Minimum partition of an independence system into independent sets\nYear: 2009\n\nAbstract: Given an independence system (E,P), the Minimum Partition Problem (MPP) seeks a partition of E into the least number of independent sets. This notion provides a unifying framework for a number of combinatorial optimisation problems, including various conditional colouring problems for graphs. The smallest integer n such that E can be partitioned into n independent sets is called the P-chromatic number of E. In this article we study MPP and the P-chromatic number with emphasis on connections with a few other well-studied optimisation problems. In particular, we show that the P-chromatic number of E is equal to the domination number of a split graph associated with (E,P). With the help of this connection we give a few upper bounds on the P-chromatic number of E in terms of some basic invariants of (E,P).","Title: Spectral Properties of Unitary Cayley Graphs of Finite Commutative Rings.\nYear: 2012\n\nAbstract: Let R be a finite commutative ring. The unitary Cayley graph of R, denoted G(R), is the graph with vertex set R and edge set {{a, b} : a, b is an element of R, a - b is an element of R-x}, where R-x is the set of units of R. An r-regular graph is Ramanujan if the absolute value of every eigenvalue of it other than +/- r is at most 2 root/r - 1. In this paper we give a necessary and sufficient condition for G(R) to be Ramanujan, and a necessary and sufficient condition for the complement of G(R) to be Ramanujan. We also determine the energy of the line graph of G(R), and compute the spectral moments of G(R) and its line graph.","Title: Routing balanced communications on hamilton decomposable networks\nYear: 2004\n\nAbstract: In |10| the authors proved upper bounds for the arc-congestion and wave- length number of any permutation demand on a bidirected ring. In this note, we give generalizations of their results in two directions. The first one is that instead of considering only permutation demands we consider any balanced demand, and the second one is that instezul of the ring network we consider any Hamilton decomposable network. Thus, we obtain upper bounds (which are best possible in general) for the arc-congestion and wavelength number of any balanced demand on a Hamilton decomposable network. As a special case, we obtain upper bounds on arc- and edge-forwarding indices of Hamilton decomposable networks that are in many caises better than the known ones.","Title: Almost Covers Of 2-Arc Transitive Graphs\nYear: 2004\n\nAbstract: Let Γ be a G-symmetric graph whose vertex set admits a nontrivial G-invariant partition ℬ with block size v. Let Γ ℬ be the quotient graph of Γ relative to ℬ and Γ[B,C] the bipartite subgraph of Γ induced by adjacent blocks B,C of ℬ. In this paper we study such graphs for which Γ ℬ is connected, (G, 2)-arc transitive and is almost covered by Γ in the sense that Γ[B,C] is a matching of v-1 ≥ 2 edges. Such graphs arose as a natural extremal case in a previous study by the author with Li and Praeger. The case Γ ℬ ≅K v+1 is covered by results of Gardiner and Praeger. We consider here the general case where Γ ℬ ≇K v+1, and prove that, for some even integer n ≥ 4, Γ ℬ is a near n-gonal graph with respect to a certain G-orbit on n-cycles of Γ ℬ. Moreover, we prove that every (G, 2)-arc transitive near n-gonal graph with respect to a G-orbit on n-cycles arises as a quotient Γ ℬ of a graph with these properties. (A near n-gonal graph is a connected graph Σ of girth at least 4 together with a set ℰ of n-cycles of Σ such that each 2-arc of Σ is contained in a unique member of ℰ.)","Title: Hamiltonicity of random graphs produced by 2-processes\nYear: 2007\n\nAbstract: Suppose that a random graph begins with n isolated vertices and evolves by edges being added at random, conditional upon all vertex degrees being at most 2. The final graph is usually 2-regular, but is not uniformly distributed. Some properties of this final graph are already known, but the asymptotic probability of being a Hamilton cycle was not known. We answer this question along with some related questions about cycles arising in the process. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007","Title: A distance-labelling problem for hypercubes\nYear: 2008\n\nAbstract: Let i\"1=i\"2=i\"3=1 be integers. An L(i\"1,i\"2,i\"3)-labelling of a graph G=(V,E) is a mapping @f:V-{0,1,2,...} such that |@f(u)-@f(v)|=i\"t for any u,v@?V with d(u,v)=t, t=1,2,3, where d(u,v) is the distance in G between u and v. The integer @f(v) is called the label assigned to v under @f, and the difference between the largest and the smallest labels is called the span of @f. The problem of finding the minimum span, @l\"i\"\"\"1\",\"i\"\"\"2\",\"i\"\"\"3(G), over all L(i\"1,i\"2,i\"3)-labellings of G arose from channel assignment in cellular communication systems, and the related problem of finding the minimum number of labels used in an L(i\"1,i\"2,i\"3)-labelling was originated from recent studies on the scalability of optical networks. In this paper we study the L(i\"1,i\"2,i\"3)-labelling problem for hypercubes Q\"d (d=3) and obtain upper and lower bounds on @l\"i\"\"\"1\",\"i\"\"\"2\",\"i\"\"\"3(Q\"d) for any (i\"1,i\"2,i\"3).","Title: Diameter and connectivity of 3-arc graphs\nYear: 2010\n\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a given graph G, X(G), is defined to have vertices the arcs of G. Two arcs uv,xy are adjacent in X(G) if and only if (v,u,x,y) is a 3-arc of G. This notion was introduced in recent studies of arc-transitive graphs. In this paper we study diameter and connectivity of 3-arc graphs. In particular, we obtain sharp bounds for the diameter and connectivity of X(G) in terms of the corresponding invariant of G.","Title: Labeling outerplanar graphs with maximum degree three\nYear: 2013\n\nAbstract: An L(2,1)-labeling of a graph G is an assignment of a non-negative integer to each vertex of G such that adjacent vertices receive integers that differ by at least two and vertices at distance two receive distinct integers. The span of such a labeling is the difference between the largest and smallest integers used. The @l-number of G, denoted by @l(G), is the minimum span over all L(2,1)-labelings of G. Bodlaender et al. conjectured that if G is an outerplanar graph of maximum degree @D, then @l(G)@?@D+2. Calamoneri and Petreschi proved that this conjecture is true when @D=8 but false when @D=3. Meanwhile, they proved that @l(G)@?@D+5 for any outerplanar graph G with @D=3 and asked whether or not this bound is sharp. In this paper we answer this question by proving that @l(G)@?@D+3 for every outerplanar graph with maximum degree @D=3. We also show that this bound @D+3 can be achieved by infinitely many outerplanar graphs with @D=3.","Title: Matroid tree graphs and interpolation theorems\nYear: 1995\n\nAbstract: Using the Hamiltonicity of matroid tree graphs we give a new proof for an interpolation theorem of Barefoot (1984) and other related results. From the proof we refine a general approach for dealing with interpolation problems of graphs.","Title: Large forbidden trade volumes and edge packings of random graphs\nYear: 2008\n\nAbstract: Let G be a graph. A G-trade of volume m is a pair (T,T^'), where each of T and T^' consists of m graphs, pairwise edge-disjoint, isomorphic to G, such that [email protected]?T^'[email protected] and the union of the edge sets of the graphs in T is identical to the union of the edge sets of the graphs in T^'. Let X(G) be the set of non-negative integers m such that no G-trade of volume m exists. In this paper we prove that, for [email protected]?G(n,12),{1,2,...,@?cn/[email protected]?}@?X(G) holds asymptotically almost surely, where c=log(4/3)/88.","Title: Interpolation theorems for graphs, hypergraphs and matroids\nYear: 1998\n\nAbstract: Let P and Q be, respectively, hereditary and cohereditary properties defined on the subsets of a finite set S . We first prove that several functions related to P and Q interpolate over some families of subsets of S . By using this we then derive a number of interpolation results for graphs, hypergraphs and matroids.","Title: Harper-type lower bounds and the bandwidths of the compositions of graphs\nYear: 1998\n\nAbstract: We give a general Harper-type lower bound for the bandwidth of a graph which is a common generalization of several known results. As applications we get a lower bound for the bandwidth of the composition of two graphs. By using this we determine the bandwidths of some composition graphs such as ( P r × P s )[ H ], ( P r × C s )[ H ] (2 r ≠ s ), ( C r × C s )[ H ] (6 ⩽ 2 r ⩽ s ), etc., for any graph H . Interestingly, the bandwidths of these graphs have nothing to do with the structure of H in general.","Title: On Isomorphisms of Minimal Cayley Graphs and Digraphs\nYear: 2001\n\nAbstract: . A Cayley graph or digraph Cay(G,S) is called a CI-graph of G if, for any T⊂G, Cay(G,S)≅Cay(G,T) if and only if S\n σ=T for some σ∈Aut(G). The aim of this paper is to characterize finite abelian groups for which all minimal Cayley graphs and digraphs are CI-graphs.","Title: Constructing a class of symmetric graphs\nYear: 2002\n\nAbstract: We find a natural construction of a large class of symmetric graphs from point- and block-transitive 1-designs. The graphs in this class can be characterized as G-symmetric graphs whose vertex sets admit a G-invariant partition B of block size at least 3 such that, for any two blocks B, C of B either there is no edge between B and C, or there exists only one vertex in B not adjacent to any vertex in C. The special case where the quotient graph ΓB of Γ relative to B is a complete graph occurs if and only if the 1-design needed in the construction is a G-doubly transitive and G-block-transitive 2-design, and in this case we give an explicit classification of Γ when G is a doubly transitive projective group or an affine group containing the affine general group. Examples of such graphs include cross ratio graphs studied recently by Gardiner, Praeger and Zhou and some other graphs with vertices the (point, line)-flags of the projective or affine geometry.","Title: Finite symmetric graphs with two-arc transitive quotients\nYear: 2005\n\nAbstract: This paper forms part of a study of 2-arc transitivity for finite imprimitive symmetric graphs, namely for graphs Γ admitting an automorphism group G that is transitive on ordered pairs of adjacent vertices, and leaves invariant a nontrivial vertex partition B. Such a group G is also transitive on the ordered pairs of adjacent vertices of the quotient graph ΓB corresponding to B. If in addition G is transitive on the 2-arcs of Γ (that is, on vertex triples (α, β γ) such that α, β and β, γ are adjacent and α ≠ γ), then G is not in general transitive on the 2-arcs of ΓB, although it does have this property in the special case where B is the orbit set of a vertex-intransitive normal subgroup of G. On the other hand, G is sometimes transitive on the 2-arcs of ΓB even if it is not transitive on the 2-arcs of Γ. We study conditions under which G is transitive on the 2-arcs of ΓB. Our conditions relate to the structure of the bipartite graph induced on B ∪ C for adjacent blocks B, C of B and a graph structure induced on B. We obtain necessary and sufficient conditions for G to be transitive on the 2-arcs of one or both of Γ, ΓB, for certain families of imprimitive symmetric graphs.","Title: The L(2, 1)-labelling problem for cubic Cayley graphs on dihedral groups.\nYear: 2013\n\nAbstract: A k-L(2,1)-labelling of a graph G is a mapping f:V(G)→{0,1,2,.,k} such that |f(u)-f(v)|≥2 if uvεE(G) and f(u)≠f(v) if u,v are distance two apart. The smallest positive integer k such that G admits a k-L(2,1)-labelling is called the λ-number of G. In this paper we study this quantity for cubic Cayley graphs (other than the prism graphs) on dihedral groups, which are called brick product graphs or honeycomb toroidal graphs. We prove that the λ-number of such a graph is between 5 and 7, and moreover we give a characterisation of such graphs with λ-number 5. © 2012 Springer Science+Business Media, LLC.","Title: Distance Labelling Problems for Hypercubes and Hamming Graphs – A Survey\nYear: 2007\n\nAbstract: We survey recent results on a few distance labelling problems for hypercubes and Hamming graphs.","Title: Domination number and neighbourhood conditions\nYear: 1999\n\nAbstract: The domination number γ of a graph G is the minimum cardinality of a subset D of vertices of G such that each vertex outside D is adjacent to at least one vertex in D . For any subset A of the vertex set of G , let ∂ + ( A ) be the set of vertices not in A which are adjacent to at least one vertex in A . Let N (A) be the union of A and ∂ + ( A ), and d ( A ) be the sum of degrees of all the vertices of A . In this paper we prove the inequality 2q ⩽ (p−γ)(p−γ+2)−|∂ + (A)| (p−γ+1)+d( N (A)) , and characterize the extremal graphs for which the equality holds, where p and q are the numbers of vertices and edges of G , respectively. From this we then get an upper bound for γ which generalizes the known upper bound γ⩽p+1− 2q+1 . Let I ( A ) be the set of vertices adjacent to all vertices of A , and I (A) be the union of A and I ( A ). We prove that 2q ⩽ (p − γ − | I (A)| + 2)(p − γ + 4) + d( I (A)) − min {p − γ − | I (A)| + 2, |A|, |I(A)|, 3} , which implies an upper bound for γ as well.","Title: A sequential coloring algorithm for finite sets\nYear: 1999\n\nAbstract: Let X be a finite set and P a hereditary property associated with the subsets of X . A partition of X into n subsets each with property P is said to be a P-n -coloring of X . The minimum n such that a P-n -coloring of X exists is defined to be the P -chromatic number of X . In this paper we give a sequential coloring algorithm for P -coloring X . From the algorithm we then get a few upper bounds for the P -chromatic number. In particular, we generalize the Welsh-Powell upper bound for ordinary chromatic number to the case of P -chromatic number of any finite set X .","Title: Dynamic domination in fuzzy causal networks\nYear: 2006\n\nAbstract: This paper presents a dynamic domination theory for fuzzy causal networks (FCN). There are three major contributions. First, we propose a new inference procedure based on dominating sets. Second, we introduce the concepts of dynamic and minimal dynamic dominating sets (DDS and MDDS) in an FCN. To reflect changes of dominance with time, we also introduce the concept of a dynamic dominating process (DDP) that has significant implications in many real-world problems. We pay a special attention to the minimal dynamic dominating process (MDDP) and develop rules for generating DDP and MDDP. Third, we investigate dynamic dominating sets with extended feedback, which we call effective dynamic dominating sets (EDDS), and related effective dynamic dominating process (EDDP). This study unveils a very important phenomenon in FCN: At any time t, either an EDDS exists or there is a dramatic change of the states of vertices. In the latter case we also identify the special structure of the sub-FCN induced by active vertices.","Title: Quotient FCMs-a decomposition theory for fuzzy cognitive maps\nYear: 2003\n\nAbstract: In this paper, we introduce a decomposition theory for fuzzy cognitive maps (FCM). First, we partition the set of vertices of an FCM into blocks according to an equivalence relation, and by regarding these blocks as vertices we construct a quotient FCM. Second, each block induces a natural sectional FCM of the original FCM, which inherits the topological structure as well as the inference from the original FCM. In this way, we decompose the original FCM into a quotient FCM and some sectional FCM. As a result, the analysis of the original FCM is reduced to the analysis of the quotient and sectional FCM, which are often much smaller in size and complexity. Such a reduction is important in analyzing large-scale FCM. We also propose a causal algebra in the quotient FCM, which indicates that the effect that one vertex influences another in the quotient depends on the weights and states of the vertices along directed paths from the former to the latter. To illustrate the process involved, we apply our decomposition theory to university management networks. Finally, we discuss possible approaches to partitioning an FCM and major concerns in constructing quotient FCM. The results represented in this paper provide an effective framework for calculating and simplifying causal inference patterns in complicated real-world applications.","Title: Optimal radio labellings of complete m-ary trees\nYear: 2010\n\nAbstract: A radio labelling of a connected graph G is a mapping f:V(G)-{0,1,2,...} such that |f(u)-f(v)|=diam(G)-d(u,v)+1 for each pair of distinct vertices u,v@?V(G), where diam(G) is the diameter of G and d(u,v) the distance between u and v. The span of f is defined as max\"u\",\"v\"@?\"V\"(\"G\")|f(u)-f(v)|, and the radio number of G is the minimum span of a radio labelling of G. A complete m-ary tree (m=2) is a rooted tree such that each vertex of degree greater than one has exactly m children and all degree-one vertices are of equal distance (height) to the root. In this paper we determine the radio number of the complete m-ary tree for any m=2 with any height and construct explicitly an optimal radio labelling.","Title: Decycling numbers of random regular graphs\nYear: 2002\n\nAbstract: The decycling number φ(G) of a graph G is the smallest number of vertices which can be removed from G so that the resultant graph contains no cycles. In this paper, we study the decycling numbers of random regular graphs. For a random cubic graph G of order n, we prove that φ(G) = ⌈n/4 + 1/2⌉ holds asymptotically almost surely. This is the result of executing a greedy algorithm for decycling G making use of a randomly chosen Hamilton cycle. For a general random d-regular graph G of order n, where d ≥ 4, we prove that φ(G)/n can be bounded below and above asymptotically almost surely by certain constants b(d) and B(d), depending solely on d, which are determined by solving, respectively, an algebraic equation and a system of differential equations.","Title: Imprimitive symmetric graphs, 3-arc graphs and 1-designs\nYear: 2002\n\nAbstract: Let Γ be a G-symmetric graph admitting a nontrivial G-invariant partition B. For B ∈ B, let D(B)=(B,ΓB(B),I) be the 1-design in which αIC for α ∈ B and C ∈ ΓR(B) if and only if α is adjacent to at least one vertex of C, where ΓB(B) is the neighbourhood of B in the quotient graph ΓB of Γ relative to B. In a natural way the setwise stabilizer GB of B in G induces a group of automorphisms of D(B). In this paper, we study those graphs Γ such that the actions of GB on B and ΓB(B) are permutationally equivalent, that is, there exists a bijection ρ :B → ΓB(B) such that ρ(αx) = (ρ(α))x for α ∈ B and x ∈ GB. In this case the vertices of Γ can be labelled naturally by the arcs of B. By using this labelling technique we analyse ΓB, D(B) and the bipartite subgraph Γ[B, C] induced by adjacent blocks B, C of B, and study the influence of them on the structure of Γ. We prove that the class of such graphs Γ is precisely the class of those graphs obtained from G-symmetric graphs Σ and self-paired G-orbits on 3-arcs of Σ by a construction introduced in a recent paper of Li, Praeger and the author, and that Γ can be reconstructed from ΓB via this construction.","Title: Fuzzy causal networks: general model, inference, and convergence\nYear: 2006\n\nAbstract: In this paper, we first propose a general framework for fuzzy causal networks (FCNs). Then, we study the dynamics and convergence of such general FCNs. We prove that any general FCN with constant weight matrix converges to a limit cycle or a static state, or the trajectory of the FCN is not repetitive. We also prove that under certain conditions a discrete state general FCN converges to its limit cycle or static state in O(n) steps, where n is the number of vertices of the FCN. This is in striking contrast with the exponential running time 2n, which is accepted widely for classic FCNs.","Title: The L(h,1,1)-labelling problem for trees\nYear: 2010\n\nAbstract: Let h=1 be an integer. An L(h,1,1)-labelling of a (finite or infinite) graph is an assignment of nonnegative integers (labels) to its vertices such that adjacent vertices receive labels with difference at least h, and vertices distance 2 or 3 apart receive distinct labels. The span of such a labelling is the difference between the maximum and minimum labels used, and the minimum span over all L(h,1,1)-labellings is called the @l\"h\",\"1\",\"1-number of the graph. We prove that, for any integer h=1 and any finite tree T of diameter at least 3 or infinite tree T of finite maximum degree, max{max\"u\"v\"@?\"E\"(\"T\")min{d(u),d(v)}+h-1,@D\"2(T)-1}@?@l\"h\",\"1\",\"1(T)@?@D\"2(T)+h-1, and both lower and upper bounds are attainable, where @D\"2(T) is the maximum total degree of two adjacent vertices. Moreover, if h is less than or equal to the minimum degree of a non-pendant vertex of T, then @l\"h\",\"1\",\"1(T)@?@D\"2(T)+h-2. In particular, @D\"2(T)-1@?@l\"2\",\"1\",\"1(T)@?@D\"2(T). Furthermore, if T is a caterpillar and h=2, then max{max\"u\"v\"@?\"E\"(\"T\")min{d(u),d(v)}+h-1,@D\"2(T)-1}@?@l\"h\",\"1\",\"1(T)@?@D\"2(T)+h-2 with both lower and upper bounds achievable.","Title: Classification of a family of symmetric graphs with complete 2-arc-transitive quotients\nYear: 2009\n\nAbstract: In this paper we give a classification of a family of symmetric graphs with complete 2-arc-transitive quotients. Of particular interest are two subfamilies of graphs which admit an arc-transitive action of a projective linear group. The graphs in these subfamilies can be defined in terms of the cross ratio of certain 4-tuples of elements of a finite projective line, and thus may be called the second type 'cross ratio graphs', which are different from the 'cross ratio graphs' studied in [A. Gardiner, C. E. Praeger, S. Zhou, Cross-ratio graphs, J. London Math. Soc. (2) 64 (2001), 257-272]. We also give a combinatorial characterisation of such second type cross ratio graphs.","Title: Routing permutations and involutions on optical ring networks: complexity results and solution to an open problem\nYear: 2007\n\nAbstract: Given a network G and a demand D of communication requests on G, a routing for (G,D) is a set of directed paths of G, each from the source to the destination of one request of D. The Routing and Wavelength Assignment Problem seeks a routing R for (G,D) and an assignment of wavelengths to the directed paths in R such that the number of wavelengths used is minimized, subject to that any two directed paths with at least one common arc receive distinct wavelengths. In the case where G is a ring, this problem is known as the Ring Routing and Wavelength Assignment Problem (RRWA). If in addition D is symmetric (that is, (s,t)@?D implies (t,s)@?D) and the directed paths for requests (s,t) and (t,s) are required to be reverse of each other, then the problem is called the Symmetric Ring Routing and Wavelength Assignment Problem (SRRWA). A demand is called a permutation demand if, for each vertex v of G, the number of requests with source v and the number of requests with destination v are the same and are equal to 0 or 1. A symmetric permutation demand is called an involution demand. In this paper we prove that both RRWA and SRRWA are NP-complete even when restricted to involution demands. As a consequence RRWA is NP-complete when restricted to permutation demands. For general demands we prove that RRWA and SRRWA can be solved in polynomial time when the number of wavelengths is fixed. Finally, we answer in the negative an open problem posed by Gargano and Vaccaro and construct infinitely many counterexamples using involution demands.","Title: No-hole 2-distant colorings for Cayley graphs on finitely generated abelian groups\nYear: 2007\n\nAbstract: no-hole 2-distant coloring of a graph @C is an assignment c of nonnegative integers to the vertices of @C such that |c(v)-c(w)|>=2 for any two adjacent vertices v and w, and the integers used are consecutive. Whenever such a coloring exists, define nsp(@C) to be the minimum difference (over all c) between the largest and smallest integers used. In this paper we study the no-hole 2-distant coloring problem for Cayley graphs over finitely generated abelian groups. We give sufficient conditions for the existence of no-hole 2-distant colorings of such graphs, and obtain upper bounds for the minimum span nsp(@C) by using a group-theoretic approach.","Title: Distance-two labellings of Hamming graphs\nYear: 2009\n\nAbstract: Let j=k=0 be integers. An @?-L(j,k)-labelling of a graph G=(V,E) is a mapping @f:V-{0,1,2,...,@?} such that |@f(u)-@f(v)|=j if u,v are adjacent and |@f(u)-@f(v)|=k if they are distance two apart. Let @l\"j\",\"k(G) be the smallest integer @? such that G admits an @?-L(j,k)-labelling. Define @l@?\"j\",\"k(G) to be the smallest @? if G admits an @?-L(j,k)-labelling with @f(V)={0,1,2,...,@?} and ~ otherwise. An @?-cyclic L(j,k)-labelling is a mapping @f:V-Z\"@? such that |@f(u)-@f(v)|\"@?=j if u,v are adjacent and |@f(u)-@f(v)|\"@?=k if they are distance two apart, where |x|\"@?=min{x,@?-x} for x between 0 and @?. Let @s\"j\",\"k(G) be the smallest @?-1 of such a labelling, and define @s@?\"j\",\"k(G) similarly to @l@?\"j\",\"k(G). We determine @l\"2\",\"0, @l@?\"2\",\"0, @s\"2\",\"0 and @s@?\"2\",\"0 for all Hamming graphs K\"q\"\"\"1@?K\"q\"\"\"2@?...@?K\"q\"\"\"d (d=2, q\"1=q\"2=...=q\"d=2) and give optimal labellings, with the only exception being 2q@?@s@?\"2\",\"0(K\"q@?K\"q)@?2q+1 for q=4. We also prove the following ''sandwich theorem'': If q\"1 is sufficiently large then @l\"2\",\"1(G)=@l@?\"2\",\"1(G)=@s@?\"2\",\"1(G)=@s\"2\",\"1(G)=@l\"1\",\"1(G)=@l@?\"1\",\"1(G)=@s@?\"1\",\"1(G)=@s\"1\",\"1(G)=q\"1q\"2-1 for any graph G between K\"q\"\"\"1@?K\"q\"\"\"2 and K\"q\"\"\"1@?K\"q\"\"\"2@?...@?K\"q\"\"\"d, and moreover we give a labelling which is optimal for these eight invariants simultaneously.","Title: Labelling Cayley Graphs on Abelian Groups\nYear: 2005\n\nAbstract: For given integers $j \\ge k \\ge 1$, an $L(j,k)$-labelling of a graph $\\Ga$ is an assignment of labels---nonnegative integers---to the vertices of $\\Ga$ such that adjacent vertices receive labels that differ by at least $j$, and vertices distance two apart receive labels that differ by at least $k$. The span of such a labelling is the difference between the largest and the smallest labels used, and the minimum span over all $L(j,k)$-labellings of $\\Ga$ is denoted by $\\l_{j,k}(\\Ga)$. The minimum number of labels needed in an $L(j,k)$-labelling of $\\Ga$ is independent of $j$ and $k$, and is denoted by $\\mu(\\Ga)$. In this paper we introduce a general approach to $L(j,k)$-labelling Cayley graphs $\\Ga$ over Abelian groups and deriving upper bounds for $\\l_{j,k}(\\Ga)$ and $\\mu(\\Ga)$. Using this approach we obtain upper bounds on $\\l_{j,k}(\\Ga)$ and $\\mu(\\Ga)$ for graphs $\\Ga$ admitting a vertex-transitive Abelian group of automorphisms. Hypercubes $Q_d$ are examples of such graphs, and as consequences we obtain upper bounds for $\\l_{j,k}(Q_d)$ and $\\mu(Q_d)$. We also obtain the exact values of $\\l_{j,k}(\\Ga)$ ($2k \\ge j \\ge k$) and $\\mu(\\Ga)$ for some Hamming graphs $\\Ga$. The result shows that, under certain arithmetic conditions, these two invariants rely only on $k$ and the orders of the two largest complete graph factors of the Hamming graph.","Title: Imprimitive symmetric graphs with cyclic blocks\nYear: 2010\n\nAbstract: Let @C be a graph admitting an arc-transitive subgroup G of automorphisms that leaves invariant a vertex partition B with parts of size v=3. In this paper we study such graphs where: for B,C@?B connected by some edge of @C, exactly two vertices of B lie on no edge with a vertex of C; and as C runs over all parts of B connected to B these vertex pairs (ignoring multiplicities) form a cycle. We prove that this occurs if and only if v=3 or 4, and moreover we give three geometric or group theoretic constructions of infinite families of such graphs.","Title: On a class of finite symmetric graphs\nYear: 2008\n\nAbstract: Let @C be a G-symmetric graph, and let B be a nontrivial G-invariant partition of the vertex set of @C. This paper aims to characterize (@C,G) under the conditions that the quotient graph @C\"B is (G,2)-arc transitive and the induced subgraph between two adjacent blocks is 2@?K\"2 or K\"2\",\"2. The results answer two questions about the relationship between @C and @C\"B for this class of graphs.","Title: Gossiping and routing in second-kind Frobenius graphs\nYear: 2012\n\nAbstract: A Frobenius group is a permutation group which is transitive but not regular such that only the identity element can fix two points. It is well known that such a group is a semidirect product G=K@?H, where K is a nilpotent normal subgroup of G. A second-kind G-Frobenius graph is a Cayley graph @C=Cay(K,a^H@?(a^-^1)^H) for some a@?K with order 2 and =K, where H is of odd order and x^H denotes the H-orbit containing x@?K. In the case when K is abelian of odd order, we give the exact value of the minimum gossiping time of @C under the store-and-forward, all-port and full-duplex model and prove that @C admits optimal gossiping schemes with the following properties: messages are always transmitted along shortest paths; each arc is used exactly once at each time step; at each step after the initial one the arcs carrying the message originated from a given vertex form a perfect matching. In the case when K is abelian of even order, we give an upper bound on the minimum gossiping time of @C under the same model. When K is abelian, we give an algorithm for producing all-to-all routings which are optimal for both edge-forwarding and minimal edge-forwarding indices of @C, and prove that such routings are also optimal for arc-forwarding and minimal arc-forwarding indices if in addition K is of odd order. We give a family of second-kind Frobenius graphs which contains all Paley graphs and connected generalized Paley graphs of odd order as a proper subfamily. Based on this and Dirichlet's prime number theorem we show that, for any even integer r=4, there exist infinitely many second-kind Frobenius graphs with valency r and order greater than any given integer such that the kernels of the underlying Frobenius groups are abelian of odd order.","Title: Gossiping and routing in undirected triple-loop networks\nYear: 2010\n\nAbstract: Given integers n ≥ 7 and a, b, c with 1 ≤ a, b, c ≤ n - 1 such that a, n - a, b, n - b, c, n - c are pairwise distinct, the (undirected) triple-loop network TLn(a, b, c) is the degree-six graph with vertices 0, 1, 2,…,n - 1 such that each vertex x is adjacent to x ± a, x ± b, and x ± c, where the operation is modulo n. It is known that the maximum order of a connected triple-loop network of the form TLn(a, b, n - (a + b)) with given diameter d ≥ 2 is nd = 3d2 + 3d + 1, which is achieved by TLnd = TLnd(1, 3d+ 1, 3d2 - 1). In this article, we study the routing and gossiping problems for such optimal triple-loop networks under the store-and-forward, all-port, and full-duplex model, and prove that they admit “perfect” gossiping and routing schemes which exhibit many interesting features. Using a group-theoretic approach we develop for TLnd a method for systematically producing such optimal gossiping and routing schemes. Moreover, we determine the minimum gossip time, the edge- and arc-forwarding indices, and the minimal edge- and arc-forwarding indices of TLnd, and prove that our routing schemes are optimal with respect to these four indices simultaneously. As a key step towards these results, we prove that TLnd is a Frobenius graph on a Frobenius group with Frobenius kernel ℤnd, and that TLnd is arc-transitive with respect to this Frobenius group. In addition, we show that TLnd admits complete rotations. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010","Title: A study of 3-arc graphs\nYear: 2011\n\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a graph G is defined to have the arcs of G as vertices such that two arcs uv,xy are adjacent if and only if (v,u,x,y) is a 3-arc of G. In this paper, we study the independence, domination and chromatic numbers of 3-arc graphs and obtain sharp lower and upper bounds for them. We introduce a new notion of arc-coloring of a graph in studying vertex-colorings of 3-arc graphs.","Title: Upper bounds for f-domination number of graphs\nYear: 1998\n\nAbstract: For an integer-valued function f defined on the vertices of a graph G, the f-domination number gamma(f)(G) of G is the smallest cardinality of a subset D subset of or equal to V(G) such that each x is an element of V(G) - D is adjacent to at least f(x) vertices in D. When f(x) = k for all x is an element of V(G), gamma(f)(G) is the k-domination number gamma(k)(G). In this note, we give a tight upper bound for gamma(f) and an improvement of the upper bound for a special f-domination number mu(j, k) of Stracke and Volkmann (1993). Some upper bounds for gamma(k) are also obtained. (C) 1998 Elsevier Science B.V. All rights reserved.","Title: An inequality between the diameter and the inverse dual degree of a tree\nYear: 2002\n\nAbstract: Let T be a nontrivial tree with diameter D(T) and radius R(T). Let I(T) be the inverse dual degree of T which is defined to be ΣuεV(T) 1/d(u), where d(u) = (Συ∈ N(u)d(υ))/d(u) for u ∈ V(T). For any longest path P of T, denote by a(P) the number of vertices outside P with degree at least 2, b(P) the number of vertices on P with degree at least 3 and distance at least 2 to each of the end-vertices of P, and c(P) the number of vertices adjacent to one of the end-vertices of P and with degree at least 3. In this note we prove that I(T) ≥ D(T)/2+ a(P)/3 + b(P)/10 + c(P)/12 + 5/6. As a corollary we then get {R(T) + 1/3 if D(T) is odd, I(T) ≥ {R(T) + 5/6 if D(T) is even, with equality if and only if T is a path of at least four vertices. The latter inequality strengthens a conjecture made by the program Graffiti.","Title: A channel assignment problem for optical networks modelled by Cayley graphs\nYear: 2004\n\nAbstract: A problem arising from a recent study of scalability of optical networks seeks to assign channels to the vertices of a network so that vertices distance 2 apart receive distinct channels. In this paper we introduce a general channel assignment scheme for Cayley graphs on abelian groups, and derive upper bounds for the minimum number of channels needed for such graphs. As application we give a systematic way of producing near-optimal channel assignments for connected graphs admitting a vertex-transitive abelian group of automorphisms. Hypercubes are examples of such graphs, and for them our near-optimal upper bound gives rise to the one obtained recently by Wan.","Title: Hamiltonicity of 3-Arc Graphs\nYear: 2014\n\nAbstract: n arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v, u, x, y) of vertices such that both (v, u, x) and (u, x, y) are paths of length two. The 3-arc graph of a graph G is defined to have vertices the arcs of G such that two arcs uv, xy are adjacent if and only if (v, u, x, y) is a 3-arc of G. We prove that any connected 3-arc graph is hamiltonian, and all iterative 3-arc graphs of any connected graph of minimum degree at least three are hamiltonian. As a corollary we obtain that any vertex-transitive graph which is isomorphic to the 3-arc graph of a connected arc-transitive graph of degree at least three must be hamiltonian. This confirms the conjecture, for this family of vertex-transitive graphs, that all vertex-transitive graphs with finitely many exceptions are hamiltonian. We also prove that if a graph with at least four vertices is Hamilton-connected, then so are its iterative 3-arc graphs.","Title: A Linear-Time Algorithm for the Orbit Problem over Cyclic Groups.\nYear: 2014\n\nAbstract: The orbit problem is at the heart of symmetry reduction methods for model checking concurrent systems. It asks whether two given configurations in a concurrent system (represented as finite strings over some finite alphabet) are in the same orbit with respect to a given finite permutation group (represented by their generators) acting on this set of configurations by permuting indices. It is known that the problem is in general as hard as the graph isomorphism problem, whose precise complexity (whether it is solvable in polynomial-time) is a long-standing open problem. In this paper, we consider the restriction of the orbit problem when the permutation group is cyclic (i.e. generated by a single permutation), an important restriction of the problem. It is known that this subproblem is solvable in polynomial-time. Our main result is a linear-time algorithm for this subproblem.","Title: A Survey on Approximation Mechanism Design without Money for Facility Games.\nYear: 2015\n\nAbstract: In a facility game one or more facilities are placed in a metric space to serve a set of selfish agents whose addresses are their private information. In a classical facility game, each agent wants to be as close to a facility as possible, and the cost of an agent can be defined as the distance between her location and the closest facility. In an obnoxious facility game, each agent wants to be far away from all facilities, and her utility is the distance from her location to the facility set. The objective of each agent is to minimize her cost or maximize her utility. An agent may lie if, by doing so, more benefit can be obtained. We are interested in social choice mechanisms that do not utilize payments. The game designer aims at a mechanism that is strategy-proof, in the sense that any agent cannot benefit by misreporting her address, or, even better, group strategy-proof, in the sense that any coalition of agents cannot all benefit by lying. Meanwhile, it is desirable to have the mechanism to be approximately optimal with respect to a chosen objective function. Several models for such approximation mechanism design without money for facility games have been proposed. In this paper we briefly review these models and related results for both deterministic and randomized mechanisms, and meanwhile we present a general framework for approximation mechanism design without money for facility games.","Title: Linear and cyclic distance-three labellings of trees.\nYear: 2014\n\nAbstract: Given a finite or infinite graph G and positive integers ℓ,h1,h2,h3, an L(h1,h2,h3)-labelling of G with span ℓ is a mapping f:V(G)→{0,1,2,…,ℓ} such that, for i=1,2,3 and any u,v∈V(G) at distance i in G, |f(u)−f(v)|≥hi. A C(h1,h2,h3)-labelling of G with span ℓ is defined similarly by requiring |f(u)−f(v)|ℓ≥hi instead, where |x|ℓ=min{|x|,ℓ−|x|}. The minimum span of an L(h1,h2,h3)-labelling, or a C(h1,h2,h3)-labelling, of G is denoted by λh1,h2,h3(G), or σh1,h2,h3(G), respectively. Two related invariants, λh1,h2,h3∗(G) and σh1,h2,h3∗(G), are defined similarly by requiring further that for every vertex u there exists an interval Iumod(ℓ+1) or modℓ, respectively, such that the neighbours of u are assigned labels from Iu and Iv∩Iw=0̸ for every edge vw of G. A recent result asserts that the L(2,1,1)-labelling problem is NP-complete even for the class of trees. In this paper we study the L(h,p,p) and C(h,p,p) labelling problems for finite or infinite trees T with finite maximum degree, where h≥p≥1 are integers. We give sharp bounds on λh,p,p(T), λh,p,p∗(T), σh,1,1(T) and σh,1,1∗(T), together with linear time approximation algorithms for the L(h,p,p)-labelling and the C(h,1,1)-labelling problems for finite trees. We obtain the precise values of these four invariants for complete m-ary trees with height at least 4, the infinite complete m-ary tree, and the infinite (m+1)-regular tree and its finite subtrees induced by vertices up to a given level. We give sharp bounds on σh,p,p(T) and σh,p,p∗(T) for trees with maximum degree Δ≤h/p, and as a special case we obtain that σh,1,1(T)=σh,1,1∗(T)=2h+Δ−1 for any tree T with Δ≤h.","Title: Group distance magic and antimagic graphs.\nYear: 2015\n\nAbstract: Given a graph G with n vertices and an Abelian group A of order n, an A-distance antimagic labelling of G is a bijection from V (G) to A such that the vertices of G have pairwise distinct weights, where the weight of a vertex is the sum (under the operation of A) of the labels assigned to its neighbours. An A-distance magic labelling of G is a bijection from V (G) to A such that the weights of all vertices of G are equal to the same element of A. In this paper we study these new labellings under a general setting with a focus on product graphs. We prove among other things several general results on group antimagic or magic labellings for Cartesian, direct and strong products of graphs. As applications we obtain several families of graphs admitting group distance antimagic or magic labellings with respect to elementary Abelian groups, cyclic groups or direct products of such groups.","Title: Radio number of trees\nYear: 2015\n\nAbstract: A radio labeling of a graph G is a mapping f : V ( G ) ź { 0 , 1 , 2 , ź } such that | f ( u ) - f ( v ) | ź diam ( G ) + 1 - d ( u , v ) for every pair of distinct vertices u , v of G , where diam ( G ) is the diameter of G and d ( u , v ) the distance between u and v in G . The radio number of G is the smallest integer k such that G has a radio labeling f with max { f ( v ) : v ź V ( G ) } = k . We give a necessary and sufficient condition for a lower bound on the radio number of trees to be achieved, two other sufficient conditions for the same bound to be achieved by a tree, and an upper bound on the radio number of trees. Using these, we determine the radio number for three families of trees.","Title: Cores of Imprimitive Symmetric Graphs of Order a Product of Two Distinct Primes\nYear: 2016\n\nAbstract: AbstractA retract of a graph ï is an induced subgraph Ψ of ï such that there exists a homomorphism from ï to Ψ whose restriction to Ψ is the identity map. A graph is a core if it has no nontrivial retracts. In general, the minimal retracts of a graph are cores and are unique up to isomorphism; they are called the core of the graph. A graph ï is G-symmetric if G is a subgroup of the automorphism group of ï that is transitive on the vertex set and also transitive on the set of ordered pairs of adjacent vertices. If in addition the vertex set of ï admits a nontrivial partition that is preserved by G, then ï is an imprimitive G-symmetric graph. In this paper cores of imprimitive symmetric graphs ï of order a product of two distinct primes are studied. In many cases the core of ï is determined completely. In other cases it is proved that either ï is a core or its core is isomorphic to one of two graphs, and conditions on when each of these possibilities occurs is given.","Title: Three-arc graphs: Characterization and domination.\nYear: 2015\n\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a graph G is defined to have vertices the arcs of G such that two arcs uv,xy are adjacent if and only if (v,u,x,y) is a 3-arc of G. In this paper we give a characterization of 3-arc graphs and obtain sharp upper bounds on the domination number of the 3-arc graph of a graph G in terms that of G.","Title: A Family of Symmetric Graphs with Complete Quotients.\nYear: 2016\n\nAbstract: A finite graph Gamma is G-symmetric if it admits G as a group of automorphisms acting transitively on V(Gamma) and transitively on the set of ordered pairs of adjacent vertices of Gamma. If V(Gamma) admits a nontrivial G-invariant partition B such that for blocks B, C is an element of B adjacent in the quotient graph Gamma(B) relative to B, exactly one vertex of B has no neighbour in C, then we say that Gamma is an almost multicover of Gamma(B). In this case there arises a natural incidence structure D(Gamma, B) with point set B. If in addition Gamma(B) is a complete graph, then D(Gamma, B) is a (G, 2)-point-transitive and G-block -transitive 2-(vertical bar B vertical bar, m + 1, lambda) design for some m >= 1, and moreover either lambda = 1 or lambda = m + 1. In this paper we classify such graphs in the case when lambda = m + 1; this together with earlier classifications when lambda = 1 gives a complete classification of almost multicovers of complete graphs.","Title: Recursive cubes of rings as models for interconnection networks.\nYear: 2017\n\nAbstract: We study recursive cubes of rings as models for interconnection networks. We first redefine each of them as a Cayley graph on the semidirect product of an elementary abelian group by a cyclic group in order to facilitate the study of them by using algebraic tools. We give an algorithm for computing shortest paths and the distance between any two vertices in recursive cubes of rings, and obtain the exact value of their diameters. We obtain sharp bounds on the Wiener index, vertex-forwarding index, edge-forwarding index and bisection width of recursive cubes of rings. The cube-connected cycles and cube-of-rings are special recursive cubes of rings, and hence all results obtained in the paper apply to these well-known networks.","Title: Networking for Big Data: A Survey.\nYear: 2017\n\nAbstract: Complementary to the fancy big data applications, networking for big data is an indispensable supporting platform for these applications in practice. This emerging research branch has gained extensive attention from both academia and industry in recent years. In this new territory, researchers are facing many unprecedented theoretical and practical challenges. We are therefore motivated to solicit...","Title: Vertex-imprimitive symmetric graphs with exactly one edge between any two distinct blocks.\nYear: 2017\n\nAbstract: A graph Γ is called G-symmetric if it admits G as a group of automorphisms acting transitively on the set of ordered pairs of adjacent vertices. We give a classification of G-symmetric graphs Γ with V(Γ) admitting a nontrivial G-invariant partition B such that there is exactly one edge of Γ between any two distinct blocks of B. This is achieved by giving a classification of (G,2)-point-transitive and G-block-transitive designs D together with G-orbits Ω on the flag set of D such that Gσ,L is transitive on L∖{σ} and L∩N={σ} for distinct (σ,L),(σ,N)∈Ω, where Gσ,L is the setwise stabilizer of L in the stabilizer Gσ of σ in G. Along the way we determine all imprimitive blocks of Gσ on V∖{σ} for every 2-transitive group G on a set V, where σ∈V.","Title: Weak metacirculants of odd prime power order.\nYear: 2018\n\nAbstract: Metacirculants are a basic and well-studied family of vertex-transitive graphs, and weak metacirculants are generalizations of them. A graph is called a weak metacirculant if it has a vertex-transitive metacyclic automorphism group. This paper is devoted to the study of weak metacirculants with odd prime power order. We first prove that a weak metacirculant of odd prime power order is a metacirculant if and only if it has a vertex-transitive split metacyclic automorphism group. We then prove that for any odd prime p and integer ℓ≥4, there exist weak metacirculants of order pℓ which are Cayley graphs but not Cayley graphs of any metacyclic group; this answers a question in Li et al. (2013) [11] We construct such graphs explicitly by introducing a construction which is a generalization of generalized Petersen graphs. Finally, we determine all smallest possible metacirculants of odd prime power order which are Cayley graphs but not Cayley graphs of any metacyclic group.","Title: Perfect Codes in Cayley Graphs.\nYear: 2018\n\nAbstract: Given a graph Gamma, a subset C of V(Gamma) is called a perfect code in Gamma if every vertex of Gamma is at distance no more than one to exactly one vertex in C, and a subset C of V(Gamma) is called a total perfect code in Gamma if every vertex of Gamma is adjacent to exactly one vertex in C. In this paper we study perfect codes and total perfect codes in Cayley graphs, with a focus on the following themes: when a subgroup of a given group is a (total) perfect code in a Cayley graph of the group; and how to construct new (total) perfect codes in a Cayley graph from known ones using automorphisms of the underlying group. We prove several results around these questions.","Title: The Isoperimetric Number of the Incidence Graph of $PG(n, q)$.\nYear: 2018\n\nAbstract: Let Gamma(n,q) be the point-hyperplane incidence graph of the projective space PG(n, q), where n >= 2 is an integer and q a prime power. We determine the order of magnitude of 1 - i(V)(Gamma(n,q)), where i(V)(Gamma(n,q)) is the vertex-isoperimetric number of Gamma(n,q). We also obtain the exact values of i(V)(Gamma(n,q)) and the related incidence-free number of Gamma(2)(,q) for q <= 16.","Title: Hadwiger's conjecture for squares of 2-trees.\nYear: 2019\n\nAbstract: Hadwiger’s conjecture asserts that any graph contains a clique minor with order no less than the chromatic number of the graph. We prove that this well-known conjecture is true for all graphs if and only if it is true for squares of split graphs. This observation implies that Hadwiger’s conjecture for squares of chordal graphs is as difficult as the general case, since chordal graphs are a superclass of split graphs. Then we consider 2-trees which are a subclass of each of planar graphs, 2-degenerate graphs and chordal graphs. We prove that Hadwiger’s conjecture is true for squares of 2-trees. We achieve this by proving the following stronger result: for any 2-tree T, its square T2 has a clique minor of order χ(T2) for which each branch set induces a path, where χ(T2) is the chromatic number of T2.","Title: Perfect codes in circulant graphs.\nYear: 2017\n\nAbstract: A perfect code in a graph =(V,E) is a subset C of V that is an independent set such that every vertex in VC is adjacent to exactly one vertex in C. A total perfect code in is a subset C of V such that every vertex of V is adjacent to exactly one vertex in C. A perfect code in the Hamming graph H(n,q) agrees with a q-ary perfect 1-code of length n in the classical setting. In this paper we give a necessary and sufficient condition for a circulant graph of degree p1 to admit a perfect code, where p is an odd prime. We also obtain a necessary and sufficient condition for a circulant graph of order n and degree pl1 to have a perfect code, where p is a prime and pl the largest power of p dividing n. Similar results for total perfect codes are also obtained in the paper.","Title: The vertex-isoperimetric number of the incidence and non-incidence graphs of unitals\nYear: 2019\n\nAbstract: We derive upper and lower bounds for the vertex-isoperimetric number of the incidence graphs of unitals and determine its order of magnitude. In the case when a unital contains sufficiently large arcs, these bounds agree and give rise to the precise value of this parameter. In particular, we obtain the exact value of the vertex-isoperimetric number of the incidence graphs of classical unitals and a certain subfamily of BM-unitals. In the case when the maximum size of arcs in the unital is relatively small, we obtain an upper bound for this parameter in terms of the vertex-isoperimetric number of the incidence graph. We also determine the exact value of the vertex-isoperimetric number of the non-incidence graph of any unital.","Title: Stability of circulant graphs\nYear: 2019\n\nAbstract: The canonical double cover D(Γ) of a graph Γ is the direct product of Γ and K2. If Aut(D(Γ))=Aut(Γ)×Z2 then Γ is called stable; otherwise Γ is called unstable. An unstable graph is nontrivially unstable if it is connected, non-bipartite and distinct vertices have different neighborhoods. In this paper we prove that every circulant graph of odd prime order is stable and there is no arc-transitive nontrivially unstable circulant graph. The latter answers a question of Wilson in 2008. We also give infinitely many counterexamples to a conjecture of Marušič, Scapellato and Zagaglia Salvi in 1989 by constructing a family of stable circulant graphs with compatible adjacency matrices.","Title: Affine flag graphs and classification of a family of symmetric graphs with complete quotients.\nYear: 2019\n\nAbstract: A graph Γ is G-symmetric if G is a group of automorphisms of Γ which is transitive on the set of ordered pairs of adjacent vertices of Γ. If V(Γ) admits a nontrivial G-invariant partition B such that for blocks B,C∈B adjacent in the quotient graph ΓB of Γ relative to B, exactly one vertex of B has no neighbour in C, then Γ is called an almost multicover of ΓB. In this case an incidence structure with point set B arises naturally, and it is a (G,2)-point-transitive and G-block-transitive 2-design if in addition ΓB is a complete graph. In this paper we classify all G-symmetric graphs Γ such that (i) B has block size |B|≥3; (ii) ΓB is complete and almost multi-covered by Γ; (iii) the incidence structure involved is a linear space; and (iv) G contains a regular normal subgroup which is elementary abelian. This classification together with earlier results in Gardiner and Praeger (2018), Giulietti et al. (2013) and Fang et al. (2016) completes the classification of symmetric graphs satisfying (i) and (ii).","Title: Subgroup perfect codes in Cayley graphs.\nYear: 2020\n\nAbstract: Let Gamma be a graph with vertex set V(Gamma). A subset C of V(Gamma) is called a perfect code in Gamma if C is an independent set of Gamma and every vertex in V(Gamma) \\C is adjacent to exactly one vertex in C. A subset C of a group G is called a perfect code of G if there exists a Cayley graph of G which admits C as a perfect code. A group G is said to be code-perfect if every proper subgroup of G is a perfect code of G. In this paper we prove that a group is code-perfect if and only if it has no elements of order 4. We also prove that a proper subgroup H of an abelian group G is a perfect code of G if and only if the Sylow 2-subgroup of H is a perfect code of the Sylow 2-subgroup of G. This reduces the problem of determining when a given subgroup of an abelian group is a perfect code to the case of abelian 2-groups. Finally, we determine all subgroup perfect codes in any generalized quaternion group.","Title: <p>On subgroup perfect codes in Cayley graphs (vol 101, 103461, 2022)</p>\nYear: 2022\n\nAbstract: We correct the statements of two theorems and two corollaries in our paper Zhang and Zhou (2021). Proofs of these theorems and three other results are given as well.(c) 2021 Elsevier Ltd. All rights reserved.","Title: Eigenvalues of Cayley Graphs\nYear: 2022\n\nAbstract: We survey some of the known results on eigenvalues of Cayley graphs and their applications, together with related results on eigenvalues of Cayley digraphs and generalizations of Cayley graphs."],"string":"[\n \"Title: Unitary Graphs.\\nYear: 2014\\n\\nAbstract: Unitary graphs are arc-transitive graphs with vertices the flags of Hermitian unitals and edges defined by certain elements of the underlying finite fields. They played a significant role in a recent classification of a class of arc-transitive graphs that admit an automorphism group acting imprimitively on the vertices. In this paper we prove that all unitary graphs are connected of diameter two and girth three. Based on this we obtain, for any prime power $q > 2$, a lower bound of order $O(\\\\Delta^{5/3})$ on the maximum number of vertices in an arc-transitive graph of degree $\\\\Delta = q(q^2-1)$ and diameter two.\",\n \"Title: Rotational circulant graphs\\nYear: 2014\\n\\nAbstract: A Frobenius group is a transitive permutation group which is not regular but only the identity element can fix two points. Such a group can be expressed as the semidirect product G = K ¿ H of a nilpotent normal subgroup K and another group H fixing a point. A first-kind G -Frobenius graph is a connected Cayley graph on K with connection set an H -orbit a H on K that generates K , where H has an even order or a is an involution. It is known that the first-kind Frobenius graphs admit attractive routing and gossiping algorithms. A complete rotation in a Cayley graph on a group G with connection set S is an automorphism of G fixing S setwise and permuting the elements of S cyclically. It is known that if the fixed-point set of such a complete rotation is an independent set and not a vertex-cut, then the gossiping time of the Cayley graph (under a certain model) attains the smallest possible value. In this paper we classify all first-kind Frobenius circulant graphs that admit complete rotations, and describe a means to construct them. This result can be stated as a necessary and sufficient condition for a first-kind Frobenius circulant to be 2-cell embeddable on a closed orientable surface as a balanced regular Cayley map. We construct a family of non-Frobenius circulants admitting complete rotations such that the corresponding fixed-point sets are independent and not vertex-cuts. We also give an infinite family of counterexamples to the conjecture that the fixed-point set of every complete rotation of a Cayley graph is not a vertex-cut.\",\n \"Title: A Class of Arc-Transitive Cayley Graphs as Models for Interconnection Networks\\nYear: 2009\\n\\nAbstract: We study a class of Cayley graphs as models for interconnection networks. With focus on efficient communication we prove that for any graph in the class there exists a gossiping protocol which exhibits attractive features, and, moreover, we give an algorithm for constructing such a protocol. In particular, these hold for two important subclasses of graphs, namely, Cayley graphs admitting a complete rotation and Frobenius graphs of a certain type. For such Frobenius graphs, we obtain the minimum gossip time and give an optimal gossiping protocol under which messages are transmitted along shortest paths and each arc is used exactly once at each time step. Moreover, for such Frobenius graphs we construct an all-to-all shortest path routing that is arc-transitive, edge- and arc-uniform, and optimal for the edge- and arc-forwarding indices simultaneously.\",\n \"Title: Frobenius circulant graphs of valency six, Eisenstein-Jacobi networks, and hexagonal meshes\\nYear: 2014\\n\\nAbstract: A Frobenius group is a transitive but not regular permutation group such that only the identity element can fix two points. A finite Frobenius group can be expressed as G=K@?H with K a nilpotent normal subgroup. A first-kind G-Frobenius graph is a Cayley graph on K with connection set S an H-orbit on K generating K, where H is of even order or S consists of involutions. We classify all 6-valent first-kind Frobenius circulant graphs such that the underlying kernel K is cyclic. We give optimal gossiping and routing algorithms for such a circulant and compute its forwarding indices, Wiener indices and minimum gossip time. We also prove that its broadcasting time is equal to its diameter plus two or three. We prove that all 6-valent first-kind Frobenius circulants with cyclic kernels are Eisenstein-Jacobi graphs, the latter being Cayley graphs on quotient rings of the ring of Eisenstein-Jacobi integers. We also prove that larger Eisenstein-Jacobi graphs can be constructed from smaller ones as topological covers, and a similar result holds for 6-valent first-kind Frobenius circulants. As a corollary any Eisenstein-Jacobi graph with order congruent to 1 modulo 6 and underlying Eisenstein-Jacobi integer not an associate of a real integer, is a cover of a 6-valent first-kind Frobenius circulant. A distributed real-time computing architecture known as HARTS or hexagonal mesh is a special 6-valent first-kind Frobenius circulant.\",\n \"Title: Finite locally-quasiprimitive graphs\\nYear: 2002\\n\\nAbstract: A finite graph is said to be locally-quasiprimitive relative to a subgroup G of automorphisms if, for all vertices α, the stabiliser in G of α is quasiprimitive on the set of vertices adjacent to α. (A permutation group is said to be quasiprimitive if all of its non-trivial normal subgroups are transitive.) The graph theoretic condition of local quasiprimitivity is strictly weaker than the conditions of local primitivity and 2-arc transitivity which have been studied previously. It is shown that the family of locally-quasiprimitive graphs is closed under the formation of a certain kind of quotient graph, called a normal quotient, induced by a normal subgroup. Moreover, a locally-quasiprimitive graph is proved to be a multicover of each of its normal quotients. Thus finite locally-quasiprimitive graphs which are minimal in the sense that they have no non-trivial proper normal quotients form an important sub-family, since each finite locally-quasiprimitive graph has at least one such graph as a normal quotient. These minimal graphs in the family are called \\\"basic\\\" locally-quasiprimitive graphs, and their structure is analysed. The process of constructing locally-quasiprimitive graphs with a given locally-quasiprimitive graph Σ as a normal quotient is then considered. It turns out that this can be viewed as a problem of constructing covering graphs of certain multigraphs associated with Σ. Further, it is shown that, under certain conditions, a locally-quasiprimitive graph can be reconstructed from knowledge of two of its normal quotients. Finally a series of open problems is presented.\",\n \"Title: Minimum partition of an independence system into independent sets\\nYear: 2009\\n\\nAbstract: Given an independence system (E,P), the Minimum Partition Problem (MPP) seeks a partition of E into the least number of independent sets. This notion provides a unifying framework for a number of combinatorial optimisation problems, including various conditional colouring problems for graphs. The smallest integer n such that E can be partitioned into n independent sets is called the P-chromatic number of E. In this article we study MPP and the P-chromatic number with emphasis on connections with a few other well-studied optimisation problems. In particular, we show that the P-chromatic number of E is equal to the domination number of a split graph associated with (E,P). With the help of this connection we give a few upper bounds on the P-chromatic number of E in terms of some basic invariants of (E,P).\",\n \"Title: Spectral Properties of Unitary Cayley Graphs of Finite Commutative Rings.\\nYear: 2012\\n\\nAbstract: Let R be a finite commutative ring. The unitary Cayley graph of R, denoted G(R), is the graph with vertex set R and edge set {{a, b} : a, b is an element of R, a - b is an element of R-x}, where R-x is the set of units of R. An r-regular graph is Ramanujan if the absolute value of every eigenvalue of it other than +/- r is at most 2 root/r - 1. In this paper we give a necessary and sufficient condition for G(R) to be Ramanujan, and a necessary and sufficient condition for the complement of G(R) to be Ramanujan. We also determine the energy of the line graph of G(R), and compute the spectral moments of G(R) and its line graph.\",\n \"Title: Routing balanced communications on hamilton decomposable networks\\nYear: 2004\\n\\nAbstract: In |10| the authors proved upper bounds for the arc-congestion and wave- length number of any permutation demand on a bidirected ring. In this note, we give generalizations of their results in two directions. The first one is that instead of considering only permutation demands we consider any balanced demand, and the second one is that instezul of the ring network we consider any Hamilton decomposable network. Thus, we obtain upper bounds (which are best possible in general) for the arc-congestion and wavelength number of any balanced demand on a Hamilton decomposable network. As a special case, we obtain upper bounds on arc- and edge-forwarding indices of Hamilton decomposable networks that are in many caises better than the known ones.\",\n \"Title: Almost Covers Of 2-Arc Transitive Graphs\\nYear: 2004\\n\\nAbstract: Let Γ be a G-symmetric graph whose vertex set admits a nontrivial G-invariant partition ℬ with block size v. Let Γ ℬ be the quotient graph of Γ relative to ℬ and Γ[B,C] the bipartite subgraph of Γ induced by adjacent blocks B,C of ℬ. In this paper we study such graphs for which Γ ℬ is connected, (G, 2)-arc transitive and is almost covered by Γ in the sense that Γ[B,C] is a matching of v-1 ≥ 2 edges. Such graphs arose as a natural extremal case in a previous study by the author with Li and Praeger. The case Γ ℬ ≅K v+1 is covered by results of Gardiner and Praeger. We consider here the general case where Γ ℬ ≇K v+1, and prove that, for some even integer n ≥ 4, Γ ℬ is a near n-gonal graph with respect to a certain G-orbit on n-cycles of Γ ℬ. Moreover, we prove that every (G, 2)-arc transitive near n-gonal graph with respect to a G-orbit on n-cycles arises as a quotient Γ ℬ of a graph with these properties. (A near n-gonal graph is a connected graph Σ of girth at least 4 together with a set ℰ of n-cycles of Σ such that each 2-arc of Σ is contained in a unique member of ℰ.)\",\n \"Title: Hamiltonicity of random graphs produced by 2-processes\\nYear: 2007\\n\\nAbstract: Suppose that a random graph begins with n isolated vertices and evolves by edges being added at random, conditional upon all vertex degrees being at most 2. The final graph is usually 2-regular, but is not uniformly distributed. Some properties of this final graph are already known, but the asymptotic probability of being a Hamilton cycle was not known. We answer this question along with some related questions about cycles arising in the process. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2007\",\n \"Title: A distance-labelling problem for hypercubes\\nYear: 2008\\n\\nAbstract: Let i\\\"1=i\\\"2=i\\\"3=1 be integers. An L(i\\\"1,i\\\"2,i\\\"3)-labelling of a graph G=(V,E) is a mapping @f:V-{0,1,2,...} such that |@f(u)-@f(v)|=i\\\"t for any u,v@?V with d(u,v)=t, t=1,2,3, where d(u,v) is the distance in G between u and v. The integer @f(v) is called the label assigned to v under @f, and the difference between the largest and the smallest labels is called the span of @f. The problem of finding the minimum span, @l\\\"i\\\"\\\"\\\"1\\\",\\\"i\\\"\\\"\\\"2\\\",\\\"i\\\"\\\"\\\"3(G), over all L(i\\\"1,i\\\"2,i\\\"3)-labellings of G arose from channel assignment in cellular communication systems, and the related problem of finding the minimum number of labels used in an L(i\\\"1,i\\\"2,i\\\"3)-labelling was originated from recent studies on the scalability of optical networks. In this paper we study the L(i\\\"1,i\\\"2,i\\\"3)-labelling problem for hypercubes Q\\\"d (d=3) and obtain upper and lower bounds on @l\\\"i\\\"\\\"\\\"1\\\",\\\"i\\\"\\\"\\\"2\\\",\\\"i\\\"\\\"\\\"3(Q\\\"d) for any (i\\\"1,i\\\"2,i\\\"3).\",\n \"Title: Diameter and connectivity of 3-arc graphs\\nYear: 2010\\n\\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a given graph G, X(G), is defined to have vertices the arcs of G. Two arcs uv,xy are adjacent in X(G) if and only if (v,u,x,y) is a 3-arc of G. This notion was introduced in recent studies of arc-transitive graphs. In this paper we study diameter and connectivity of 3-arc graphs. In particular, we obtain sharp bounds for the diameter and connectivity of X(G) in terms of the corresponding invariant of G.\",\n \"Title: Labeling outerplanar graphs with maximum degree three\\nYear: 2013\\n\\nAbstract: An L(2,1)-labeling of a graph G is an assignment of a non-negative integer to each vertex of G such that adjacent vertices receive integers that differ by at least two and vertices at distance two receive distinct integers. The span of such a labeling is the difference between the largest and smallest integers used. The @l-number of G, denoted by @l(G), is the minimum span over all L(2,1)-labelings of G. Bodlaender et al. conjectured that if G is an outerplanar graph of maximum degree @D, then @l(G)@?@D+2. Calamoneri and Petreschi proved that this conjecture is true when @D=8 but false when @D=3. Meanwhile, they proved that @l(G)@?@D+5 for any outerplanar graph G with @D=3 and asked whether or not this bound is sharp. In this paper we answer this question by proving that @l(G)@?@D+3 for every outerplanar graph with maximum degree @D=3. We also show that this bound @D+3 can be achieved by infinitely many outerplanar graphs with @D=3.\",\n \"Title: Matroid tree graphs and interpolation theorems\\nYear: 1995\\n\\nAbstract: Using the Hamiltonicity of matroid tree graphs we give a new proof for an interpolation theorem of Barefoot (1984) and other related results. From the proof we refine a general approach for dealing with interpolation problems of graphs.\",\n \"Title: Large forbidden trade volumes and edge packings of random graphs\\nYear: 2008\\n\\nAbstract: Let G be a graph. A G-trade of volume m is a pair (T,T^'), where each of T and T^' consists of m graphs, pairwise edge-disjoint, isomorphic to G, such that [email protected]?T^'[email protected] and the union of the edge sets of the graphs in T is identical to the union of the edge sets of the graphs in T^'. Let X(G) be the set of non-negative integers m such that no G-trade of volume m exists. In this paper we prove that, for [email protected]?G(n,12),{1,2,...,@?cn/[email protected]?}@?X(G) holds asymptotically almost surely, where c=log(4/3)/88.\",\n \"Title: Interpolation theorems for graphs, hypergraphs and matroids\\nYear: 1998\\n\\nAbstract: Let P and Q be, respectively, hereditary and cohereditary properties defined on the subsets of a finite set S . We first prove that several functions related to P and Q interpolate over some families of subsets of S . By using this we then derive a number of interpolation results for graphs, hypergraphs and matroids.\",\n \"Title: Harper-type lower bounds and the bandwidths of the compositions of graphs\\nYear: 1998\\n\\nAbstract: We give a general Harper-type lower bound for the bandwidth of a graph which is a common generalization of several known results. As applications we get a lower bound for the bandwidth of the composition of two graphs. By using this we determine the bandwidths of some composition graphs such as ( P r × P s )[ H ], ( P r × C s )[ H ] (2 r ≠ s ), ( C r × C s )[ H ] (6 ⩽ 2 r ⩽ s ), etc., for any graph H . Interestingly, the bandwidths of these graphs have nothing to do with the structure of H in general.\",\n \"Title: On Isomorphisms of Minimal Cayley Graphs and Digraphs\\nYear: 2001\\n\\nAbstract: . A Cayley graph or digraph Cay(G,S) is called a CI-graph of G if, for any T⊂G, Cay(G,S)≅Cay(G,T) if and only if S\\n σ=T for some σ∈Aut(G). The aim of this paper is to characterize finite abelian groups for which all minimal Cayley graphs and digraphs are CI-graphs.\",\n \"Title: Constructing a class of symmetric graphs\\nYear: 2002\\n\\nAbstract: We find a natural construction of a large class of symmetric graphs from point- and block-transitive 1-designs. The graphs in this class can be characterized as G-symmetric graphs whose vertex sets admit a G-invariant partition B of block size at least 3 such that, for any two blocks B, C of B either there is no edge between B and C, or there exists only one vertex in B not adjacent to any vertex in C. The special case where the quotient graph ΓB of Γ relative to B is a complete graph occurs if and only if the 1-design needed in the construction is a G-doubly transitive and G-block-transitive 2-design, and in this case we give an explicit classification of Γ when G is a doubly transitive projective group or an affine group containing the affine general group. Examples of such graphs include cross ratio graphs studied recently by Gardiner, Praeger and Zhou and some other graphs with vertices the (point, line)-flags of the projective or affine geometry.\",\n \"Title: Finite symmetric graphs with two-arc transitive quotients\\nYear: 2005\\n\\nAbstract: This paper forms part of a study of 2-arc transitivity for finite imprimitive symmetric graphs, namely for graphs Γ admitting an automorphism group G that is transitive on ordered pairs of adjacent vertices, and leaves invariant a nontrivial vertex partition B. Such a group G is also transitive on the ordered pairs of adjacent vertices of the quotient graph ΓB corresponding to B. If in addition G is transitive on the 2-arcs of Γ (that is, on vertex triples (α, β γ) such that α, β and β, γ are adjacent and α ≠ γ), then G is not in general transitive on the 2-arcs of ΓB, although it does have this property in the special case where B is the orbit set of a vertex-intransitive normal subgroup of G. On the other hand, G is sometimes transitive on the 2-arcs of ΓB even if it is not transitive on the 2-arcs of Γ. We study conditions under which G is transitive on the 2-arcs of ΓB. Our conditions relate to the structure of the bipartite graph induced on B ∪ C for adjacent blocks B, C of B and a graph structure induced on B. We obtain necessary and sufficient conditions for G to be transitive on the 2-arcs of one or both of Γ, ΓB, for certain families of imprimitive symmetric graphs.\",\n \"Title: The L(2, 1)-labelling problem for cubic Cayley graphs on dihedral groups.\\nYear: 2013\\n\\nAbstract: A k-L(2,1)-labelling of a graph G is a mapping f:V(G)→{0,1,2,.,k} such that |f(u)-f(v)|≥2 if uvεE(G) and f(u)≠f(v) if u,v are distance two apart. The smallest positive integer k such that G admits a k-L(2,1)-labelling is called the λ-number of G. In this paper we study this quantity for cubic Cayley graphs (other than the prism graphs) on dihedral groups, which are called brick product graphs or honeycomb toroidal graphs. We prove that the λ-number of such a graph is between 5 and 7, and moreover we give a characterisation of such graphs with λ-number 5. © 2012 Springer Science+Business Media, LLC.\",\n \"Title: Distance Labelling Problems for Hypercubes and Hamming Graphs – A Survey\\nYear: 2007\\n\\nAbstract: We survey recent results on a few distance labelling problems for hypercubes and Hamming graphs.\",\n \"Title: Domination number and neighbourhood conditions\\nYear: 1999\\n\\nAbstract: The domination number γ of a graph G is the minimum cardinality of a subset D of vertices of G such that each vertex outside D is adjacent to at least one vertex in D . For any subset A of the vertex set of G , let ∂ + ( A ) be the set of vertices not in A which are adjacent to at least one vertex in A . Let N (A) be the union of A and ∂ + ( A ), and d ( A ) be the sum of degrees of all the vertices of A . In this paper we prove the inequality 2q ⩽ (p−γ)(p−γ+2)−|∂ + (A)| (p−γ+1)+d( N (A)) , and characterize the extremal graphs for which the equality holds, where p and q are the numbers of vertices and edges of G , respectively. From this we then get an upper bound for γ which generalizes the known upper bound γ⩽p+1− 2q+1 . Let I ( A ) be the set of vertices adjacent to all vertices of A , and I (A) be the union of A and I ( A ). We prove that 2q ⩽ (p − γ − | I (A)| + 2)(p − γ + 4) + d( I (A)) − min {p − γ − | I (A)| + 2, |A|, |I(A)|, 3} , which implies an upper bound for γ as well.\",\n \"Title: A sequential coloring algorithm for finite sets\\nYear: 1999\\n\\nAbstract: Let X be a finite set and P a hereditary property associated with the subsets of X . A partition of X into n subsets each with property P is said to be a P-n -coloring of X . The minimum n such that a P-n -coloring of X exists is defined to be the P -chromatic number of X . In this paper we give a sequential coloring algorithm for P -coloring X . From the algorithm we then get a few upper bounds for the P -chromatic number. In particular, we generalize the Welsh-Powell upper bound for ordinary chromatic number to the case of P -chromatic number of any finite set X .\",\n \"Title: Dynamic domination in fuzzy causal networks\\nYear: 2006\\n\\nAbstract: This paper presents a dynamic domination theory for fuzzy causal networks (FCN). There are three major contributions. First, we propose a new inference procedure based on dominating sets. Second, we introduce the concepts of dynamic and minimal dynamic dominating sets (DDS and MDDS) in an FCN. To reflect changes of dominance with time, we also introduce the concept of a dynamic dominating process (DDP) that has significant implications in many real-world problems. We pay a special attention to the minimal dynamic dominating process (MDDP) and develop rules for generating DDP and MDDP. Third, we investigate dynamic dominating sets with extended feedback, which we call effective dynamic dominating sets (EDDS), and related effective dynamic dominating process (EDDP). This study unveils a very important phenomenon in FCN: At any time t, either an EDDS exists or there is a dramatic change of the states of vertices. In the latter case we also identify the special structure of the sub-FCN induced by active vertices.\",\n \"Title: Quotient FCMs-a decomposition theory for fuzzy cognitive maps\\nYear: 2003\\n\\nAbstract: In this paper, we introduce a decomposition theory for fuzzy cognitive maps (FCM). First, we partition the set of vertices of an FCM into blocks according to an equivalence relation, and by regarding these blocks as vertices we construct a quotient FCM. Second, each block induces a natural sectional FCM of the original FCM, which inherits the topological structure as well as the inference from the original FCM. In this way, we decompose the original FCM into a quotient FCM and some sectional FCM. As a result, the analysis of the original FCM is reduced to the analysis of the quotient and sectional FCM, which are often much smaller in size and complexity. Such a reduction is important in analyzing large-scale FCM. We also propose a causal algebra in the quotient FCM, which indicates that the effect that one vertex influences another in the quotient depends on the weights and states of the vertices along directed paths from the former to the latter. To illustrate the process involved, we apply our decomposition theory to university management networks. Finally, we discuss possible approaches to partitioning an FCM and major concerns in constructing quotient FCM. The results represented in this paper provide an effective framework for calculating and simplifying causal inference patterns in complicated real-world applications.\",\n \"Title: Optimal radio labellings of complete m-ary trees\\nYear: 2010\\n\\nAbstract: A radio labelling of a connected graph G is a mapping f:V(G)-{0,1,2,...} such that |f(u)-f(v)|=diam(G)-d(u,v)+1 for each pair of distinct vertices u,v@?V(G), where diam(G) is the diameter of G and d(u,v) the distance between u and v. The span of f is defined as max\\\"u\\\",\\\"v\\\"@?\\\"V\\\"(\\\"G\\\")|f(u)-f(v)|, and the radio number of G is the minimum span of a radio labelling of G. A complete m-ary tree (m=2) is a rooted tree such that each vertex of degree greater than one has exactly m children and all degree-one vertices are of equal distance (height) to the root. In this paper we determine the radio number of the complete m-ary tree for any m=2 with any height and construct explicitly an optimal radio labelling.\",\n \"Title: Decycling numbers of random regular graphs\\nYear: 2002\\n\\nAbstract: The decycling number φ(G) of a graph G is the smallest number of vertices which can be removed from G so that the resultant graph contains no cycles. In this paper, we study the decycling numbers of random regular graphs. For a random cubic graph G of order n, we prove that φ(G) = ⌈n/4 + 1/2⌉ holds asymptotically almost surely. This is the result of executing a greedy algorithm for decycling G making use of a randomly chosen Hamilton cycle. For a general random d-regular graph G of order n, where d ≥ 4, we prove that φ(G)/n can be bounded below and above asymptotically almost surely by certain constants b(d) and B(d), depending solely on d, which are determined by solving, respectively, an algebraic equation and a system of differential equations.\",\n \"Title: Imprimitive symmetric graphs, 3-arc graphs and 1-designs\\nYear: 2002\\n\\nAbstract: Let Γ be a G-symmetric graph admitting a nontrivial G-invariant partition B. For B ∈ B, let D(B)=(B,ΓB(B),I) be the 1-design in which αIC for α ∈ B and C ∈ ΓR(B) if and only if α is adjacent to at least one vertex of C, where ΓB(B) is the neighbourhood of B in the quotient graph ΓB of Γ relative to B. In a natural way the setwise stabilizer GB of B in G induces a group of automorphisms of D(B). In this paper, we study those graphs Γ such that the actions of GB on B and ΓB(B) are permutationally equivalent, that is, there exists a bijection ρ :B → ΓB(B) such that ρ(αx) = (ρ(α))x for α ∈ B and x ∈ GB. In this case the vertices of Γ can be labelled naturally by the arcs of B. By using this labelling technique we analyse ΓB, D(B) and the bipartite subgraph Γ[B, C] induced by adjacent blocks B, C of B, and study the influence of them on the structure of Γ. We prove that the class of such graphs Γ is precisely the class of those graphs obtained from G-symmetric graphs Σ and self-paired G-orbits on 3-arcs of Σ by a construction introduced in a recent paper of Li, Praeger and the author, and that Γ can be reconstructed from ΓB via this construction.\",\n \"Title: Fuzzy causal networks: general model, inference, and convergence\\nYear: 2006\\n\\nAbstract: In this paper, we first propose a general framework for fuzzy causal networks (FCNs). Then, we study the dynamics and convergence of such general FCNs. We prove that any general FCN with constant weight matrix converges to a limit cycle or a static state, or the trajectory of the FCN is not repetitive. We also prove that under certain conditions a discrete state general FCN converges to its limit cycle or static state in O(n) steps, where n is the number of vertices of the FCN. This is in striking contrast with the exponential running time 2n, which is accepted widely for classic FCNs.\",\n \"Title: The L(h,1,1)-labelling problem for trees\\nYear: 2010\\n\\nAbstract: Let h=1 be an integer. An L(h,1,1)-labelling of a (finite or infinite) graph is an assignment of nonnegative integers (labels) to its vertices such that adjacent vertices receive labels with difference at least h, and vertices distance 2 or 3 apart receive distinct labels. The span of such a labelling is the difference between the maximum and minimum labels used, and the minimum span over all L(h,1,1)-labellings is called the @l\\\"h\\\",\\\"1\\\",\\\"1-number of the graph. We prove that, for any integer h=1 and any finite tree T of diameter at least 3 or infinite tree T of finite maximum degree, max{max\\\"u\\\"v\\\"@?\\\"E\\\"(\\\"T\\\")min{d(u),d(v)}+h-1,@D\\\"2(T)-1}@?@l\\\"h\\\",\\\"1\\\",\\\"1(T)@?@D\\\"2(T)+h-1, and both lower and upper bounds are attainable, where @D\\\"2(T) is the maximum total degree of two adjacent vertices. Moreover, if h is less than or equal to the minimum degree of a non-pendant vertex of T, then @l\\\"h\\\",\\\"1\\\",\\\"1(T)@?@D\\\"2(T)+h-2. In particular, @D\\\"2(T)-1@?@l\\\"2\\\",\\\"1\\\",\\\"1(T)@?@D\\\"2(T). Furthermore, if T is a caterpillar and h=2, then max{max\\\"u\\\"v\\\"@?\\\"E\\\"(\\\"T\\\")min{d(u),d(v)}+h-1,@D\\\"2(T)-1}@?@l\\\"h\\\",\\\"1\\\",\\\"1(T)@?@D\\\"2(T)+h-2 with both lower and upper bounds achievable.\",\n \"Title: Classification of a family of symmetric graphs with complete 2-arc-transitive quotients\\nYear: 2009\\n\\nAbstract: In this paper we give a classification of a family of symmetric graphs with complete 2-arc-transitive quotients. Of particular interest are two subfamilies of graphs which admit an arc-transitive action of a projective linear group. The graphs in these subfamilies can be defined in terms of the cross ratio of certain 4-tuples of elements of a finite projective line, and thus may be called the second type 'cross ratio graphs', which are different from the 'cross ratio graphs' studied in [A. Gardiner, C. E. Praeger, S. Zhou, Cross-ratio graphs, J. London Math. Soc. (2) 64 (2001), 257-272]. We also give a combinatorial characterisation of such second type cross ratio graphs.\",\n \"Title: Routing permutations and involutions on optical ring networks: complexity results and solution to an open problem\\nYear: 2007\\n\\nAbstract: Given a network G and a demand D of communication requests on G, a routing for (G,D) is a set of directed paths of G, each from the source to the destination of one request of D. The Routing and Wavelength Assignment Problem seeks a routing R for (G,D) and an assignment of wavelengths to the directed paths in R such that the number of wavelengths used is minimized, subject to that any two directed paths with at least one common arc receive distinct wavelengths. In the case where G is a ring, this problem is known as the Ring Routing and Wavelength Assignment Problem (RRWA). If in addition D is symmetric (that is, (s,t)@?D implies (t,s)@?D) and the directed paths for requests (s,t) and (t,s) are required to be reverse of each other, then the problem is called the Symmetric Ring Routing and Wavelength Assignment Problem (SRRWA). A demand is called a permutation demand if, for each vertex v of G, the number of requests with source v and the number of requests with destination v are the same and are equal to 0 or 1. A symmetric permutation demand is called an involution demand. In this paper we prove that both RRWA and SRRWA are NP-complete even when restricted to involution demands. As a consequence RRWA is NP-complete when restricted to permutation demands. For general demands we prove that RRWA and SRRWA can be solved in polynomial time when the number of wavelengths is fixed. Finally, we answer in the negative an open problem posed by Gargano and Vaccaro and construct infinitely many counterexamples using involution demands.\",\n \"Title: No-hole 2-distant colorings for Cayley graphs on finitely generated abelian groups\\nYear: 2007\\n\\nAbstract: no-hole 2-distant coloring of a graph @C is an assignment c of nonnegative integers to the vertices of @C such that |c(v)-c(w)|>=2 for any two adjacent vertices v and w, and the integers used are consecutive. Whenever such a coloring exists, define nsp(@C) to be the minimum difference (over all c) between the largest and smallest integers used. In this paper we study the no-hole 2-distant coloring problem for Cayley graphs over finitely generated abelian groups. We give sufficient conditions for the existence of no-hole 2-distant colorings of such graphs, and obtain upper bounds for the minimum span nsp(@C) by using a group-theoretic approach.\",\n \"Title: Distance-two labellings of Hamming graphs\\nYear: 2009\\n\\nAbstract: Let j=k=0 be integers. An @?-L(j,k)-labelling of a graph G=(V,E) is a mapping @f:V-{0,1,2,...,@?} such that |@f(u)-@f(v)|=j if u,v are adjacent and |@f(u)-@f(v)|=k if they are distance two apart. Let @l\\\"j\\\",\\\"k(G) be the smallest integer @? such that G admits an @?-L(j,k)-labelling. Define @l@?\\\"j\\\",\\\"k(G) to be the smallest @? if G admits an @?-L(j,k)-labelling with @f(V)={0,1,2,...,@?} and ~ otherwise. An @?-cyclic L(j,k)-labelling is a mapping @f:V-Z\\\"@? such that |@f(u)-@f(v)|\\\"@?=j if u,v are adjacent and |@f(u)-@f(v)|\\\"@?=k if they are distance two apart, where |x|\\\"@?=min{x,@?-x} for x between 0 and @?. Let @s\\\"j\\\",\\\"k(G) be the smallest @?-1 of such a labelling, and define @s@?\\\"j\\\",\\\"k(G) similarly to @l@?\\\"j\\\",\\\"k(G). We determine @l\\\"2\\\",\\\"0, @l@?\\\"2\\\",\\\"0, @s\\\"2\\\",\\\"0 and @s@?\\\"2\\\",\\\"0 for all Hamming graphs K\\\"q\\\"\\\"\\\"1@?K\\\"q\\\"\\\"\\\"2@?...@?K\\\"q\\\"\\\"\\\"d (d=2, q\\\"1=q\\\"2=...=q\\\"d=2) and give optimal labellings, with the only exception being 2q@?@s@?\\\"2\\\",\\\"0(K\\\"q@?K\\\"q)@?2q+1 for q=4. We also prove the following ''sandwich theorem'': If q\\\"1 is sufficiently large then @l\\\"2\\\",\\\"1(G)=@l@?\\\"2\\\",\\\"1(G)=@s@?\\\"2\\\",\\\"1(G)=@s\\\"2\\\",\\\"1(G)=@l\\\"1\\\",\\\"1(G)=@l@?\\\"1\\\",\\\"1(G)=@s@?\\\"1\\\",\\\"1(G)=@s\\\"1\\\",\\\"1(G)=q\\\"1q\\\"2-1 for any graph G between K\\\"q\\\"\\\"\\\"1@?K\\\"q\\\"\\\"\\\"2 and K\\\"q\\\"\\\"\\\"1@?K\\\"q\\\"\\\"\\\"2@?...@?K\\\"q\\\"\\\"\\\"d, and moreover we give a labelling which is optimal for these eight invariants simultaneously.\",\n \"Title: Labelling Cayley Graphs on Abelian Groups\\nYear: 2005\\n\\nAbstract: For given integers $j \\\\ge k \\\\ge 1$, an $L(j,k)$-labelling of a graph $\\\\Ga$ is an assignment of labels---nonnegative integers---to the vertices of $\\\\Ga$ such that adjacent vertices receive labels that differ by at least $j$, and vertices distance two apart receive labels that differ by at least $k$. The span of such a labelling is the difference between the largest and the smallest labels used, and the minimum span over all $L(j,k)$-labellings of $\\\\Ga$ is denoted by $\\\\l_{j,k}(\\\\Ga)$. The minimum number of labels needed in an $L(j,k)$-labelling of $\\\\Ga$ is independent of $j$ and $k$, and is denoted by $\\\\mu(\\\\Ga)$. In this paper we introduce a general approach to $L(j,k)$-labelling Cayley graphs $\\\\Ga$ over Abelian groups and deriving upper bounds for $\\\\l_{j,k}(\\\\Ga)$ and $\\\\mu(\\\\Ga)$. Using this approach we obtain upper bounds on $\\\\l_{j,k}(\\\\Ga)$ and $\\\\mu(\\\\Ga)$ for graphs $\\\\Ga$ admitting a vertex-transitive Abelian group of automorphisms. Hypercubes $Q_d$ are examples of such graphs, and as consequences we obtain upper bounds for $\\\\l_{j,k}(Q_d)$ and $\\\\mu(Q_d)$. We also obtain the exact values of $\\\\l_{j,k}(\\\\Ga)$ ($2k \\\\ge j \\\\ge k$) and $\\\\mu(\\\\Ga)$ for some Hamming graphs $\\\\Ga$. The result shows that, under certain arithmetic conditions, these two invariants rely only on $k$ and the orders of the two largest complete graph factors of the Hamming graph.\",\n \"Title: Imprimitive symmetric graphs with cyclic blocks\\nYear: 2010\\n\\nAbstract: Let @C be a graph admitting an arc-transitive subgroup G of automorphisms that leaves invariant a vertex partition B with parts of size v=3. In this paper we study such graphs where: for B,C@?B connected by some edge of @C, exactly two vertices of B lie on no edge with a vertex of C; and as C runs over all parts of B connected to B these vertex pairs (ignoring multiplicities) form a cycle. We prove that this occurs if and only if v=3 or 4, and moreover we give three geometric or group theoretic constructions of infinite families of such graphs.\",\n \"Title: On a class of finite symmetric graphs\\nYear: 2008\\n\\nAbstract: Let @C be a G-symmetric graph, and let B be a nontrivial G-invariant partition of the vertex set of @C. This paper aims to characterize (@C,G) under the conditions that the quotient graph @C\\\"B is (G,2)-arc transitive and the induced subgraph between two adjacent blocks is 2@?K\\\"2 or K\\\"2\\\",\\\"2. The results answer two questions about the relationship between @C and @C\\\"B for this class of graphs.\",\n \"Title: Gossiping and routing in second-kind Frobenius graphs\\nYear: 2012\\n\\nAbstract: A Frobenius group is a permutation group which is transitive but not regular such that only the identity element can fix two points. It is well known that such a group is a semidirect product G=K@?H, where K is a nilpotent normal subgroup of G. A second-kind G-Frobenius graph is a Cayley graph @C=Cay(K,a^H@?(a^-^1)^H) for some a@?K with order 2 and =K, where H is of odd order and x^H denotes the H-orbit containing x@?K. In the case when K is abelian of odd order, we give the exact value of the minimum gossiping time of @C under the store-and-forward, all-port and full-duplex model and prove that @C admits optimal gossiping schemes with the following properties: messages are always transmitted along shortest paths; each arc is used exactly once at each time step; at each step after the initial one the arcs carrying the message originated from a given vertex form a perfect matching. In the case when K is abelian of even order, we give an upper bound on the minimum gossiping time of @C under the same model. When K is abelian, we give an algorithm for producing all-to-all routings which are optimal for both edge-forwarding and minimal edge-forwarding indices of @C, and prove that such routings are also optimal for arc-forwarding and minimal arc-forwarding indices if in addition K is of odd order. We give a family of second-kind Frobenius graphs which contains all Paley graphs and connected generalized Paley graphs of odd order as a proper subfamily. Based on this and Dirichlet's prime number theorem we show that, for any even integer r=4, there exist infinitely many second-kind Frobenius graphs with valency r and order greater than any given integer such that the kernels of the underlying Frobenius groups are abelian of odd order.\",\n \"Title: Gossiping and routing in undirected triple-loop networks\\nYear: 2010\\n\\nAbstract: Given integers n ≥ 7 and a, b, c with 1 ≤ a, b, c ≤ n - 1 such that a, n - a, b, n - b, c, n - c are pairwise distinct, the (undirected) triple-loop network TLn(a, b, c) is the degree-six graph with vertices 0, 1, 2,…,n - 1 such that each vertex x is adjacent to x ± a, x ± b, and x ± c, where the operation is modulo n. It is known that the maximum order of a connected triple-loop network of the form TLn(a, b, n - (a + b)) with given diameter d ≥ 2 is nd = 3d2 + 3d + 1, which is achieved by TLnd = TLnd(1, 3d+ 1, 3d2 - 1). In this article, we study the routing and gossiping problems for such optimal triple-loop networks under the store-and-forward, all-port, and full-duplex model, and prove that they admit “perfect” gossiping and routing schemes which exhibit many interesting features. Using a group-theoretic approach we develop for TLnd a method for systematically producing such optimal gossiping and routing schemes. Moreover, we determine the minimum gossip time, the edge- and arc-forwarding indices, and the minimal edge- and arc-forwarding indices of TLnd, and prove that our routing schemes are optimal with respect to these four indices simultaneously. As a key step towards these results, we prove that TLnd is a Frobenius graph on a Frobenius group with Frobenius kernel ℤnd, and that TLnd is arc-transitive with respect to this Frobenius group. In addition, we show that TLnd admits complete rotations. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010\",\n \"Title: A study of 3-arc graphs\\nYear: 2011\\n\\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a graph G is defined to have the arcs of G as vertices such that two arcs uv,xy are adjacent if and only if (v,u,x,y) is a 3-arc of G. In this paper, we study the independence, domination and chromatic numbers of 3-arc graphs and obtain sharp lower and upper bounds for them. We introduce a new notion of arc-coloring of a graph in studying vertex-colorings of 3-arc graphs.\",\n \"Title: Upper bounds for f-domination number of graphs\\nYear: 1998\\n\\nAbstract: For an integer-valued function f defined on the vertices of a graph G, the f-domination number gamma(f)(G) of G is the smallest cardinality of a subset D subset of or equal to V(G) such that each x is an element of V(G) - D is adjacent to at least f(x) vertices in D. When f(x) = k for all x is an element of V(G), gamma(f)(G) is the k-domination number gamma(k)(G). In this note, we give a tight upper bound for gamma(f) and an improvement of the upper bound for a special f-domination number mu(j, k) of Stracke and Volkmann (1993). Some upper bounds for gamma(k) are also obtained. (C) 1998 Elsevier Science B.V. All rights reserved.\",\n \"Title: An inequality between the diameter and the inverse dual degree of a tree\\nYear: 2002\\n\\nAbstract: Let T be a nontrivial tree with diameter D(T) and radius R(T). Let I(T) be the inverse dual degree of T which is defined to be ΣuεV(T) 1/d(u), where d(u) = (Συ∈ N(u)d(υ))/d(u) for u ∈ V(T). For any longest path P of T, denote by a(P) the number of vertices outside P with degree at least 2, b(P) the number of vertices on P with degree at least 3 and distance at least 2 to each of the end-vertices of P, and c(P) the number of vertices adjacent to one of the end-vertices of P and with degree at least 3. In this note we prove that I(T) ≥ D(T)/2+ a(P)/3 + b(P)/10 + c(P)/12 + 5/6. As a corollary we then get {R(T) + 1/3 if D(T) is odd, I(T) ≥ {R(T) + 5/6 if D(T) is even, with equality if and only if T is a path of at least four vertices. The latter inequality strengthens a conjecture made by the program Graffiti.\",\n \"Title: A channel assignment problem for optical networks modelled by Cayley graphs\\nYear: 2004\\n\\nAbstract: A problem arising from a recent study of scalability of optical networks seeks to assign channels to the vertices of a network so that vertices distance 2 apart receive distinct channels. In this paper we introduce a general channel assignment scheme for Cayley graphs on abelian groups, and derive upper bounds for the minimum number of channels needed for such graphs. As application we give a systematic way of producing near-optimal channel assignments for connected graphs admitting a vertex-transitive abelian group of automorphisms. Hypercubes are examples of such graphs, and for them our near-optimal upper bound gives rise to the one obtained recently by Wan.\",\n \"Title: Hamiltonicity of 3-Arc Graphs\\nYear: 2014\\n\\nAbstract: n arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v, u, x, y) of vertices such that both (v, u, x) and (u, x, y) are paths of length two. The 3-arc graph of a graph G is defined to have vertices the arcs of G such that two arcs uv, xy are adjacent if and only if (v, u, x, y) is a 3-arc of G. We prove that any connected 3-arc graph is hamiltonian, and all iterative 3-arc graphs of any connected graph of minimum degree at least three are hamiltonian. As a corollary we obtain that any vertex-transitive graph which is isomorphic to the 3-arc graph of a connected arc-transitive graph of degree at least three must be hamiltonian. This confirms the conjecture, for this family of vertex-transitive graphs, that all vertex-transitive graphs with finitely many exceptions are hamiltonian. We also prove that if a graph with at least four vertices is Hamilton-connected, then so are its iterative 3-arc graphs.\",\n \"Title: A Linear-Time Algorithm for the Orbit Problem over Cyclic Groups.\\nYear: 2014\\n\\nAbstract: The orbit problem is at the heart of symmetry reduction methods for model checking concurrent systems. It asks whether two given configurations in a concurrent system (represented as finite strings over some finite alphabet) are in the same orbit with respect to a given finite permutation group (represented by their generators) acting on this set of configurations by permuting indices. It is known that the problem is in general as hard as the graph isomorphism problem, whose precise complexity (whether it is solvable in polynomial-time) is a long-standing open problem. In this paper, we consider the restriction of the orbit problem when the permutation group is cyclic (i.e. generated by a single permutation), an important restriction of the problem. It is known that this subproblem is solvable in polynomial-time. Our main result is a linear-time algorithm for this subproblem.\",\n \"Title: A Survey on Approximation Mechanism Design without Money for Facility Games.\\nYear: 2015\\n\\nAbstract: In a facility game one or more facilities are placed in a metric space to serve a set of selfish agents whose addresses are their private information. In a classical facility game, each agent wants to be as close to a facility as possible, and the cost of an agent can be defined as the distance between her location and the closest facility. In an obnoxious facility game, each agent wants to be far away from all facilities, and her utility is the distance from her location to the facility set. The objective of each agent is to minimize her cost or maximize her utility. An agent may lie if, by doing so, more benefit can be obtained. We are interested in social choice mechanisms that do not utilize payments. The game designer aims at a mechanism that is strategy-proof, in the sense that any agent cannot benefit by misreporting her address, or, even better, group strategy-proof, in the sense that any coalition of agents cannot all benefit by lying. Meanwhile, it is desirable to have the mechanism to be approximately optimal with respect to a chosen objective function. Several models for such approximation mechanism design without money for facility games have been proposed. In this paper we briefly review these models and related results for both deterministic and randomized mechanisms, and meanwhile we present a general framework for approximation mechanism design without money for facility games.\",\n \"Title: Linear and cyclic distance-three labellings of trees.\\nYear: 2014\\n\\nAbstract: Given a finite or infinite graph G and positive integers ℓ,h1,h2,h3, an L(h1,h2,h3)-labelling of G with span ℓ is a mapping f:V(G)→{0,1,2,…,ℓ} such that, for i=1,2,3 and any u,v∈V(G) at distance i in G, |f(u)−f(v)|≥hi. A C(h1,h2,h3)-labelling of G with span ℓ is defined similarly by requiring |f(u)−f(v)|ℓ≥hi instead, where |x|ℓ=min{|x|,ℓ−|x|}. The minimum span of an L(h1,h2,h3)-labelling, or a C(h1,h2,h3)-labelling, of G is denoted by λh1,h2,h3(G), or σh1,h2,h3(G), respectively. Two related invariants, λh1,h2,h3∗(G) and σh1,h2,h3∗(G), are defined similarly by requiring further that for every vertex u there exists an interval Iumod(ℓ+1) or modℓ, respectively, such that the neighbours of u are assigned labels from Iu and Iv∩Iw=0̸ for every edge vw of G. A recent result asserts that the L(2,1,1)-labelling problem is NP-complete even for the class of trees. In this paper we study the L(h,p,p) and C(h,p,p) labelling problems for finite or infinite trees T with finite maximum degree, where h≥p≥1 are integers. We give sharp bounds on λh,p,p(T), λh,p,p∗(T), σh,1,1(T) and σh,1,1∗(T), together with linear time approximation algorithms for the L(h,p,p)-labelling and the C(h,1,1)-labelling problems for finite trees. We obtain the precise values of these four invariants for complete m-ary trees with height at least 4, the infinite complete m-ary tree, and the infinite (m+1)-regular tree and its finite subtrees induced by vertices up to a given level. We give sharp bounds on σh,p,p(T) and σh,p,p∗(T) for trees with maximum degree Δ≤h/p, and as a special case we obtain that σh,1,1(T)=σh,1,1∗(T)=2h+Δ−1 for any tree T with Δ≤h.\",\n \"Title: Group distance magic and antimagic graphs.\\nYear: 2015\\n\\nAbstract: Given a graph G with n vertices and an Abelian group A of order n, an A-distance antimagic labelling of G is a bijection from V (G) to A such that the vertices of G have pairwise distinct weights, where the weight of a vertex is the sum (under the operation of A) of the labels assigned to its neighbours. An A-distance magic labelling of G is a bijection from V (G) to A such that the weights of all vertices of G are equal to the same element of A. In this paper we study these new labellings under a general setting with a focus on product graphs. We prove among other things several general results on group antimagic or magic labellings for Cartesian, direct and strong products of graphs. As applications we obtain several families of graphs admitting group distance antimagic or magic labellings with respect to elementary Abelian groups, cyclic groups or direct products of such groups.\",\n \"Title: Radio number of trees\\nYear: 2015\\n\\nAbstract: A radio labeling of a graph G is a mapping f : V ( G ) ź { 0 , 1 , 2 , ź } such that | f ( u ) - f ( v ) | ź diam ( G ) + 1 - d ( u , v ) for every pair of distinct vertices u , v of G , where diam ( G ) is the diameter of G and d ( u , v ) the distance between u and v in G . The radio number of G is the smallest integer k such that G has a radio labeling f with max { f ( v ) : v ź V ( G ) } = k . We give a necessary and sufficient condition for a lower bound on the radio number of trees to be achieved, two other sufficient conditions for the same bound to be achieved by a tree, and an upper bound on the radio number of trees. Using these, we determine the radio number for three families of trees.\",\n \"Title: Cores of Imprimitive Symmetric Graphs of Order a Product of Two Distinct Primes\\nYear: 2016\\n\\nAbstract: AbstractA retract of a graph ï is an induced subgraph Ψ of ï such that there exists a homomorphism from ï to Ψ whose restriction to Ψ is the identity map. A graph is a core if it has no nontrivial retracts. In general, the minimal retracts of a graph are cores and are unique up to isomorphism; they are called the core of the graph. A graph ï is G-symmetric if G is a subgroup of the automorphism group of ï that is transitive on the vertex set and also transitive on the set of ordered pairs of adjacent vertices. If in addition the vertex set of ï admits a nontrivial partition that is preserved by G, then ï is an imprimitive G-symmetric graph. In this paper cores of imprimitive symmetric graphs ï of order a product of two distinct primes are studied. In many cases the core of ï is determined completely. In other cases it is proved that either ï is a core or its core is isomorphic to one of two graphs, and conditions on when each of these possibilities occurs is given.\",\n \"Title: Three-arc graphs: Characterization and domination.\\nYear: 2015\\n\\nAbstract: An arc of a graph is an oriented edge and a 3-arc is a 4-tuple (v,u,x,y) of vertices such that both (v,u,x) and (u,x,y) are paths of length two. The 3-arc graph of a graph G is defined to have vertices the arcs of G such that two arcs uv,xy are adjacent if and only if (v,u,x,y) is a 3-arc of G. In this paper we give a characterization of 3-arc graphs and obtain sharp upper bounds on the domination number of the 3-arc graph of a graph G in terms that of G.\",\n \"Title: A Family of Symmetric Graphs with Complete Quotients.\\nYear: 2016\\n\\nAbstract: A finite graph Gamma is G-symmetric if it admits G as a group of automorphisms acting transitively on V(Gamma) and transitively on the set of ordered pairs of adjacent vertices of Gamma. If V(Gamma) admits a nontrivial G-invariant partition B such that for blocks B, C is an element of B adjacent in the quotient graph Gamma(B) relative to B, exactly one vertex of B has no neighbour in C, then we say that Gamma is an almost multicover of Gamma(B). In this case there arises a natural incidence structure D(Gamma, B) with point set B. If in addition Gamma(B) is a complete graph, then D(Gamma, B) is a (G, 2)-point-transitive and G-block -transitive 2-(vertical bar B vertical bar, m + 1, lambda) design for some m >= 1, and moreover either lambda = 1 or lambda = m + 1. In this paper we classify such graphs in the case when lambda = m + 1; this together with earlier classifications when lambda = 1 gives a complete classification of almost multicovers of complete graphs.\",\n \"Title: Recursive cubes of rings as models for interconnection networks.\\nYear: 2017\\n\\nAbstract: We study recursive cubes of rings as models for interconnection networks. We first redefine each of them as a Cayley graph on the semidirect product of an elementary abelian group by a cyclic group in order to facilitate the study of them by using algebraic tools. We give an algorithm for computing shortest paths and the distance between any two vertices in recursive cubes of rings, and obtain the exact value of their diameters. We obtain sharp bounds on the Wiener index, vertex-forwarding index, edge-forwarding index and bisection width of recursive cubes of rings. The cube-connected cycles and cube-of-rings are special recursive cubes of rings, and hence all results obtained in the paper apply to these well-known networks.\",\n \"Title: Networking for Big Data: A Survey.\\nYear: 2017\\n\\nAbstract: Complementary to the fancy big data applications, networking for big data is an indispensable supporting platform for these applications in practice. This emerging research branch has gained extensive attention from both academia and industry in recent years. In this new territory, researchers are facing many unprecedented theoretical and practical challenges. We are therefore motivated to solicit...\",\n \"Title: Vertex-imprimitive symmetric graphs with exactly one edge between any two distinct blocks.\\nYear: 2017\\n\\nAbstract: A graph Γ is called G-symmetric if it admits G as a group of automorphisms acting transitively on the set of ordered pairs of adjacent vertices. We give a classification of G-symmetric graphs Γ with V(Γ) admitting a nontrivial G-invariant partition B such that there is exactly one edge of Γ between any two distinct blocks of B. This is achieved by giving a classification of (G,2)-point-transitive and G-block-transitive designs D together with G-orbits Ω on the flag set of D such that Gσ,L is transitive on L∖{σ} and L∩N={σ} for distinct (σ,L),(σ,N)∈Ω, where Gσ,L is the setwise stabilizer of L in the stabilizer Gσ of σ in G. Along the way we determine all imprimitive blocks of Gσ on V∖{σ} for every 2-transitive group G on a set V, where σ∈V.\",\n \"Title: Weak metacirculants of odd prime power order.\\nYear: 2018\\n\\nAbstract: Metacirculants are a basic and well-studied family of vertex-transitive graphs, and weak metacirculants are generalizations of them. A graph is called a weak metacirculant if it has a vertex-transitive metacyclic automorphism group. This paper is devoted to the study of weak metacirculants with odd prime power order. We first prove that a weak metacirculant of odd prime power order is a metacirculant if and only if it has a vertex-transitive split metacyclic automorphism group. We then prove that for any odd prime p and integer ℓ≥4, there exist weak metacirculants of order pℓ which are Cayley graphs but not Cayley graphs of any metacyclic group; this answers a question in Li et al. (2013) [11] We construct such graphs explicitly by introducing a construction which is a generalization of generalized Petersen graphs. Finally, we determine all smallest possible metacirculants of odd prime power order which are Cayley graphs but not Cayley graphs of any metacyclic group.\",\n \"Title: Perfect Codes in Cayley Graphs.\\nYear: 2018\\n\\nAbstract: Given a graph Gamma, a subset C of V(Gamma) is called a perfect code in Gamma if every vertex of Gamma is at distance no more than one to exactly one vertex in C, and a subset C of V(Gamma) is called a total perfect code in Gamma if every vertex of Gamma is adjacent to exactly one vertex in C. In this paper we study perfect codes and total perfect codes in Cayley graphs, with a focus on the following themes: when a subgroup of a given group is a (total) perfect code in a Cayley graph of the group; and how to construct new (total) perfect codes in a Cayley graph from known ones using automorphisms of the underlying group. We prove several results around these questions.\",\n \"Title: The Isoperimetric Number of the Incidence Graph of $PG(n, q)$.\\nYear: 2018\\n\\nAbstract: Let Gamma(n,q) be the point-hyperplane incidence graph of the projective space PG(n, q), where n >= 2 is an integer and q a prime power. We determine the order of magnitude of 1 - i(V)(Gamma(n,q)), where i(V)(Gamma(n,q)) is the vertex-isoperimetric number of Gamma(n,q). We also obtain the exact values of i(V)(Gamma(n,q)) and the related incidence-free number of Gamma(2)(,q) for q <= 16.\",\n \"Title: Hadwiger's conjecture for squares of 2-trees.\\nYear: 2019\\n\\nAbstract: Hadwiger’s conjecture asserts that any graph contains a clique minor with order no less than the chromatic number of the graph. We prove that this well-known conjecture is true for all graphs if and only if it is true for squares of split graphs. This observation implies that Hadwiger’s conjecture for squares of chordal graphs is as difficult as the general case, since chordal graphs are a superclass of split graphs. Then we consider 2-trees which are a subclass of each of planar graphs, 2-degenerate graphs and chordal graphs. We prove that Hadwiger’s conjecture is true for squares of 2-trees. We achieve this by proving the following stronger result: for any 2-tree T, its square T2 has a clique minor of order χ(T2) for which each branch set induces a path, where χ(T2) is the chromatic number of T2.\",\n \"Title: Perfect codes in circulant graphs.\\nYear: 2017\\n\\nAbstract: A perfect code in a graph =(V,E) is a subset C of V that is an independent set such that every vertex in VC is adjacent to exactly one vertex in C. A total perfect code in is a subset C of V such that every vertex of V is adjacent to exactly one vertex in C. A perfect code in the Hamming graph H(n,q) agrees with a q-ary perfect 1-code of length n in the classical setting. In this paper we give a necessary and sufficient condition for a circulant graph of degree p1 to admit a perfect code, where p is an odd prime. We also obtain a necessary and sufficient condition for a circulant graph of order n and degree pl1 to have a perfect code, where p is a prime and pl the largest power of p dividing n. Similar results for total perfect codes are also obtained in the paper.\",\n \"Title: The vertex-isoperimetric number of the incidence and non-incidence graphs of unitals\\nYear: 2019\\n\\nAbstract: We derive upper and lower bounds for the vertex-isoperimetric number of the incidence graphs of unitals and determine its order of magnitude. In the case when a unital contains sufficiently large arcs, these bounds agree and give rise to the precise value of this parameter. In particular, we obtain the exact value of the vertex-isoperimetric number of the incidence graphs of classical unitals and a certain subfamily of BM-unitals. In the case when the maximum size of arcs in the unital is relatively small, we obtain an upper bound for this parameter in terms of the vertex-isoperimetric number of the incidence graph. We also determine the exact value of the vertex-isoperimetric number of the non-incidence graph of any unital.\",\n \"Title: Stability of circulant graphs\\nYear: 2019\\n\\nAbstract: The canonical double cover D(Γ) of a graph Γ is the direct product of Γ and K2. If Aut(D(Γ))=Aut(Γ)×Z2 then Γ is called stable; otherwise Γ is called unstable. An unstable graph is nontrivially unstable if it is connected, non-bipartite and distinct vertices have different neighborhoods. In this paper we prove that every circulant graph of odd prime order is stable and there is no arc-transitive nontrivially unstable circulant graph. The latter answers a question of Wilson in 2008. We also give infinitely many counterexamples to a conjecture of Marušič, Scapellato and Zagaglia Salvi in 1989 by constructing a family of stable circulant graphs with compatible adjacency matrices.\",\n \"Title: Affine flag graphs and classification of a family of symmetric graphs with complete quotients.\\nYear: 2019\\n\\nAbstract: A graph Γ is G-symmetric if G is a group of automorphisms of Γ which is transitive on the set of ordered pairs of adjacent vertices of Γ. If V(Γ) admits a nontrivial G-invariant partition B such that for blocks B,C∈B adjacent in the quotient graph ΓB of Γ relative to B, exactly one vertex of B has no neighbour in C, then Γ is called an almost multicover of ΓB. In this case an incidence structure with point set B arises naturally, and it is a (G,2)-point-transitive and G-block-transitive 2-design if in addition ΓB is a complete graph. In this paper we classify all G-symmetric graphs Γ such that (i) B has block size |B|≥3; (ii) ΓB is complete and almost multi-covered by Γ; (iii) the incidence structure involved is a linear space; and (iv) G contains a regular normal subgroup which is elementary abelian. This classification together with earlier results in Gardiner and Praeger (2018), Giulietti et al. (2013) and Fang et al. (2016) completes the classification of symmetric graphs satisfying (i) and (ii).\",\n \"Title: Subgroup perfect codes in Cayley graphs.\\nYear: 2020\\n\\nAbstract: Let Gamma be a graph with vertex set V(Gamma). A subset C of V(Gamma) is called a perfect code in Gamma if C is an independent set of Gamma and every vertex in V(Gamma) \\\\C is adjacent to exactly one vertex in C. A subset C of a group G is called a perfect code of G if there exists a Cayley graph of G which admits C as a perfect code. A group G is said to be code-perfect if every proper subgroup of G is a perfect code of G. In this paper we prove that a group is code-perfect if and only if it has no elements of order 4. We also prove that a proper subgroup H of an abelian group G is a perfect code of G if and only if the Sylow 2-subgroup of H is a perfect code of the Sylow 2-subgroup of G. This reduces the problem of determining when a given subgroup of an abelian group is a perfect code to the case of abelian 2-groups. Finally, we determine all subgroup perfect codes in any generalized quaternion group.\",\n \"Title: <p>On subgroup perfect codes in Cayley graphs (vol 101, 103461, 2022)</p>\\nYear: 2022\\n\\nAbstract: We correct the statements of two theorems and two corollaries in our paper Zhang and Zhou (2021). Proofs of these theorems and three other results are given as well.(c) 2021 Elsevier Ltd. All rights reserved.\",\n \"Title: Eigenvalues of Cayley Graphs\\nYear: 2022\\n\\nAbstract: We survey some of the known results on eigenvalues of Cayley graphs and their applications, together with related results on eigenvalues of Cayley digraphs and generalizations of Cayley graphs.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":67,"string":"67"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":51,"string":"51"}}},{"rowIdx":52,"cells":{"question_id":{"kind":"string","value":"Song Chong"},"question":{"kind":"string","value":"Generate an abstract for the title \"Competition-based distributed BS power activation and user scheduling algorithm\" using the following items: 1. Cellular technologies\n2. Inter-cell interference (ICI) management\n3. Distributed optimization\n4. Competition-based BS activation and user scheduling framework (CBA)\n5. Increased throughput and higher"},"answer":{"kind":"string","value":"Existing cellular technologies in unlicensed band such as license assisted access (LAA)-LTE do not capture inter-cell interference (ICI) management which becomes more important in modern small cell network environments. Moreover, existing ICI management techniques not only can be operated in only licensed frequency band due to their centralized properties, but also have high computational complexities. In this paper, by invoking distributed optimization, we propose a fully distributed base station (BS) activation and user scheduling framework which can be operated in even unlicensed band because of its competition properties. Our simulation results demonstrate that (i) proposed competition-based BS activation and user scheduling framework (CBA) increases throughput of cell edge users by 112%-335% compared to conventional algorithms, (ii) the CBA properly catches up with the performance of optimal algorithm up to 93% in terms of overall performance and up to 95% in terms of edge user throughput, and (iii) the CBA also provides higher performance gains in the larger ratio of edge users and the smaller cell size, which indicates that the CBA well adapts to cellular network trend where cells are gradually smaller and densely deployed."},"correct_answer":{"kind":"string","value":"Existing cellular technologies in unlicensed band such as license assisted access (LAA)-LTE do not capture inter-cell interference (ICI) management which becomes more important in modern small cell network environments. Moreover, existing ICI management techniques not only can be operated in only licensed frequency band due to their centralized properties, but also have high computational complexities. In this paper, by invoking distributed optimization, we propose a fully distributed base station (BS) activation and user scheduling framework which can be operated in even unlicensed band because of its competition properties. Our simulation results demonstrate that (i) proposed competition-based BS activation and user scheduling framework (CBA) increases throughput of cell edge users by 112%-335% compared to conventional algorithms, (ii) the CBA properly catches up with the performance of optimal algorithm up to 93% in terms of overall performance and up to 95% in terms of edge user throughput, and (iii) the CBA also provides higher performance gains in the larger ratio of edge users and the smaller cell size, which indicates that the CBA well adapts to cellular network trend where cells are gradually smaller and densely deployed."},"documents":{"kind":"list like","value":["Title: ExMin: A routing metric for novel opportunity gain in Delay Tolerant Networks\nYear: 2014\n\nAbstract: Delay Tolerant Networks (DTNs) are characterized by intermittently connected links formed by mobile nodes' probabilistic encounters. Most DTN routing techniques use the first encountered node who has smaller routing metric as a relay node. Prior work on DTN routing can be broadly classified into one which takes the minimum out of expected delays for all possible individual routing paths, referred to as MinEx, as a routing metric to decide the next hop relay node. Fundamentally, MinEx has no difference from the shortest path computation in conventional multi-hop networks, where a link weight is the expected inter-meeting time. However in DTNs, nodes meet intermittently by their mobility, hence the links formed from the meetings are probabilistic. In this environment, MinEx often fails to accurately estimate the actual delay since opportunism in nodes' intermittent meeting is not properly taken into account. In this paper, to exploit the true opportunism, we first propose a metric called ExMin which stochastically calculates the metric by taking the expectation of the minimum delays over all possible routes. We further show that ExMin can be computed online by relying only on local information sharing. Our extensive experiments involving three realistic network scenarios created by two vehicle traces (about 1500 Shanghai taxies and 500 San Francisco taxies) and one human mobility trace (93 KAIST students) show that ExMin outperforms MinEx by up to 30% under either of DTN environments allowing single-copy or multi-copies of a packet.","Title: Multi-Path Aggregate Flow Control for Real-Time Traffic Engineering\nYear: 2008\n\nAbstract: We present an online distributed traffic engineering method for ISP networks with multi-path routing. The method is based on edge-to-edge aggregate flow control that balances load and makes the network congestion-free in real time, responding to actual traffic demands whether they are underload or overloaded. Moreover, it allows ISPs to apply various bandwidth-sharing policies to edge-to-edge flows, as desired. Our simulations confirm that the proposed method works as designed for TCP sources that have their own end-to-end congestion control mechanism and enhance the performance and the efficiency of the the network.","Title: Downlink resource allocation in multi-carrier systems: frequency-selective vs. equal power allocation\nYear: 2008\n\nAbstract: This paper revisits equal power allocation from the viewpoint of asymptotic network utility maximization (NUM) problem in multi-carrier systems. It is a well-known fact that the equal power allocation is near optimal to the sum capacity maximization problem in high SNR (signal-to-noise ratio) regime, i.e., optimal water-filling approximates to equal power allocation in that case. Due to this property together with its simplicity, the equal power allocation has been adopted in several researches, but its performance in other problems has not been clearly understood. We evaluate the suitability of equal power allocation in NUM problem which turns into various resource sharing policies according to utility functions. Namely, our conclusion is that in frequency selective channels, the equal power allocation is near optimal for efficiency-oriented resource sharing policy, but when fairness is emphasized, its performance is severely degraded and thus frequency-selective power allocation is necessary. For this, we develop a suboptimal subcarrier and frequency-selective power allocation algorithm for asymptotic NUM problem using the gradient-based scheduling theory and compare the performance of equal power allocation and the developed algorithm. Extensive simulation results are presented to verify our arguments.","Title: Utility-Optimal Multi-Pattern Reuse in Multi-Cell Networks\nYear: 2011\n\nAbstract: Achieving sufficient spatial capacity gain through the use of small cells requires careful consideration of inter-cell interference (ICI) management via BS power coordination coupled with user scheduling inside cells. Optimal algorithms are known to be difficult to implement due to high computation and signaling overhead. This study proposes joint pattern-based ICI management and user scheduling algorithms that are practically implementable. The key idea is to decompose the original problem into two sub-problems in which ICI management is run at a slower time scale than user scheduling. We empirically show that even with such a slow tracking of system dynamics at the ICI management part, the decomposed approach achieves a considerable performance increase compared to conventional universal reuse schemes.","Title: Rate control algorithms for the ATM ABR service\nYear: 1997\n\nAbstract: Over the last couple of years both the ATM Forum and ITU-T have converged on a closed-loop, feedback based, rate control mechanism as the framework for the Available Bit Rate ATM Transfer Capability. In this framework, an ABR source adapts its transmission rate to changing characteristics of the ATM network by either testing periodically the state of the network or through direct feedback from the network. The state of the network is conveyed to the source either as it simple binary feedback signaling congestion or no congestion, or as an explicit rate indicating the rate at which the source can transmit. In this paper we review the detailed framework for the ABR service standardized by the ATM Forum, the underlying service philosophy and protocol design goals for ABR flow control, and the premises and high-level performance characteristics for the more promising ABR rate control schemes proposed so far.","Title: Performance Enhancement In Obs Network With Flow Control And Edge Delay Method\nYear: 2006\n\nAbstract: This paper examines burst contention resolution problems in optical burst switching (OBS) networks. Since burst contentions take place i) when the network is congested by increased input traffic, or ii) two or more bursts demand the same wavelength exactly at the same time even though there is no congestion. From these insights, we present two novel methods that make higher throughputs and lower burst losses in the OBS network.First, from the viewpoint of flow control, we propose a burst flow control algorithm that controls the length of a burst based on the congestion price on its path. With the proposed flow control algorithm, the OBS network achieves improved efficiency and fairness compared to the case where a burst contention resolution scheme is solely used.Next, we develop an edge delay method which decreases burst losses especially when two or more bursts are overlapped in the core nodes. When some bursts need buffering to avoid contentions at core nodes, the proposed method makes them be delayed for the required buffering time at its ingress edge instead. Through extensive simulations, we demonstrate its performance.","Title: Joint network-wide opportunistic scheduling and power control in multi-cell networks\nYear: 2009\n\nAbstract: We present a unified analytical framework that maximizes generalized utilities of a wireless network by network-wide opportunistic scheduling and power control. That is, base stations in the network jointly decide mobile stations to be served at the same time as the transmission powers of base stations are coordinated to mitigate the mutually interfering effect. Although the maximization at the first glance appears to be a mixed, twofold and nonlinear optimization requiring excessive computational complexity, we show that the maximization can be transformed into a pure binary optimization with much lower complexity. To be exact, it is proven that binary power control of base stations is necessary and sufficient for maximizing the network-wide utilities under a physical layer regime where the channel capacity is linear in the signal-to-interference-noise ratio. To further reduce the complexity of the problem, a distributed heuristic algorithm is proposed that performs much better than existing opportunistic algorithms. Through extensive simulations, it becomes clear that network-wide opportunistic scheduling and power control is most suitable for fairness-oriented networks and under loaded networks. We believe that our work will serve as a cornerstone for network-wide scheduling approaches from theoretical and practical standpoints.","Title: Making 802.11 DCF Optimal: Design, Implementation, and Evaluation\nYear: 2012\n\nAbstract: This paper proposes a new protocol called Optimal DCF (O-DCF). Inspired by a sequence of analytic results, O-DCF modifies the rule of adapting CSMA parameters, such as backoff time and transmission length, based on a function of the demand-supply differential of link capacity captured by the local queue length. Unlike clean-slate design, O-DCF is fully compatible with 802.11 hardware, so that it can be easily implemented only with a simple device driver update. Through extensive simulations and real experiments with a 16-node wireless network testbed, we evaluate the performance of O-DCF and show that it achieves near-optimality, and outperforms other competitive ones, such as 802.11 DCF, optimal CSMA, and DiffQ in a wide range of scenarios.","Title: A simple, scalable, and stable explicit rate allocation algorithm for max-min flow control with minimum rate guarantee\nYear: 2001\n\nAbstract: We present a novel control-theoretic explicit rate (ER) allocation algorithm for the max-min flow control of elastic traffic services with minimum rate guarantee in the setting of the ATM available bit rate (ABR) service. The proposed ER algorithm is simple in that the number of operations required to compute it at a switch is minimized, scalable in that per-virtual-circuit (VC) operations including per-VC queueing, per-VC accounting, and per-VC state management are virtually removed, and stable in that by employing it, the user transmission rates and the network queues are asymptotically stabilized at a unique equilibrium point at which max-min fairness with minimum rate guarantee and target queue lengths are achieved, respectively. To improve the speed of convergence, we normalize the controller gains of the algorithm by the estimate of the number of locally bottlenecked VCs. The estimation scheme is also computationally simple and scalable since it does not require per-VC accounting either. We analyze the theoretical performance of the proposed algorithm and verify its agreement with the practical performance through simulations in the case of multiple bottleneck nodes. We believe that the proposed algorithm will serve as an encouraging solution to the max-min flow control of elastic traffic services, the deployment of which has been debated long due to their lack of theoretical foundation and implementation complexity","Title: Adaptive multi-pattern reuse in multi-cell networks\nYear: 2009\n\nAbstract: Multiuser information-theoretic analysis of achievable communication rate regions over networks traditionally assumes that individual sources of information are independent. However, fully exploiting network-wide synergies requires an understanding of ...","Title: Towards optimal MAC without message passing in wireless networks\nYear: 2009\n\nAbstract: One of the key messages in significant research on cross-layer design of wireless networks over the past 15 years is that extensive message passing may be necessary to achieve optimal performance. Heavy message passing is obviously an undesirable feature for practical implementation due to its reduced actual throughput and security issues. In this paper, we first summarize our preliminary work that does not need message passing, yet achieves near-optimality. Then, we present our recent efforts to realize such an algorithmic solution in a real network, e.g., IEEE 802.11-based systems, and discuss possible future research directions.","Title: SLAW: A New Mobility Model for Human Walks\nYear: 2009\n\nAbstract: Simulating human mobility is important in mobile networks because many mobile devices are either attached to or controlled by humans and it is very hard to deploy real mobile networks whose size is controllably scalable for performance evaluation. Lately various measurement studies of human walk traces have discovered several significant statistical patterns of human mobility. Namely these include truncated power-law distributions of flights, pause-times and inter-contact times, fractal way-points, and heterogeneously defined areas of individual mobility. Unfortunately, none of existing mobility models effectively captures all of these features. This paper presents a new mobility model called SLAW (self-similar least action walk) that can produce synthetic walk traces containing all these features. This is by far the first such model. Our performance study using using SLAW generated traces indicates that SLAW is effective in representing social contexts present among people sharing common interests or those in a single community such as university campus, companies and theme parks. The social contexts are typically common gathering places where most people visit during their daily lives such as student unions, dormitory, street malls and restaurants. SLAW expresses the mobility patterns involving these contexts by fractal way points and heavy-tail flights on top of the way points. We verify through simulation that SLAW brings out the unique performance features of various mobile network routing protocols.","Title: A distributed utility max-min flow control algorithm\nYear: 2006\n\nAbstract: A fair allocation of utility (application-layer performance) is essential in providing QoS (Quality of Service) guarantee. However, there have been few researches in the literature of utility-fair network resource allocation scheme. In this paper, we propose a distributed utility max–min flow control algorithm which accommodates application diversity in that it does not require the concavity of utility functions, and is scalable in that it does not require any per-flow operation in the network. The algorithm is proved to be convergent under the assumption that there exists a single bottleneck link and the communication delay between any two links in the network is bounded. Although the convergence of the algorithm is analyzed only for the case of a single bottleneck link, we show through simulations that the proposed algorithm works as designed for the case of multiple bottleneck links as well.","Title: Performance evaluation of a DTN as a city-wide infrastructure network\nYear: 2009\n\nAbstract: As providing data networks in an urban district through a cellular system is expensive and does not provide sufficient capacity, use of a wireless mesh network is generally considered as a way to achieve more capacity. While a mesh network has sizable installation costs to deploy routers and still does not provide abundant capacity, it is worthwhile to consider a DTN whose capacity is abundant without additional installation costs to support a mesh network. In this paper, we propose an architecture of a DTN as an infrastructure network and study the capacity region of the DTN over the real mobility of Shanghai taxies. We identify and verify several key characteristics of the DTN capacity, including time-varying and asymmetric characteristics. Our simulation results show that the capacity of the DTN is superior to a mesh network most of the time for both single-link and multi-link scenarios.","Title: Combined QoS Scheduling and Call Admission Control Algorithm in Cellular Networks\nYear: 2006\n\nAbstract: In this paper, a scheduling problem in wireless networks is considered when there simultaneously exist CBR (constant bit rate) users requiring exact minimum average throughput guarantee and EMG (elastic with minimum guarantee) users requiring minimum average throughput guarantee and more if possible. By exploiting utility maximization problem without minimum throughput constraint and newly defined utility functions, we propose a combined scheduling and call admission control scheme that exactly guarantees the minimum requirements of CBR and EMG users and then allocates the leftover capacity to EMG users. In the proposed scheme, it is easy to give priority to particular users so that they are guaranteed their requirements prior to any other user. Moreover, the priority structure enables the proposed measurement-based call admission control algorithm to perform admission trial without affecting the minimum performance of existing users. We show through mathematical analysis and simulations that our scheme works as designed.","Title: Dynamic bandwidth allocation for efficient transport of real-time VBR video over ATM\nYear: 1994\n\nAbstract: The paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. The authors describe video traffic in the frequency domain: the low frequency signal captures the slow time-variation of consecutive scene changes; the high frequency signal exhibits the feature of strong frame autocorrelation. The study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low, frequency signal. Since the time scale of scene changes is usually in the range of a second or longer, the low frequency video signal is defined in a well-founded low frequency band. Hence, it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: the recursive least square method vs. the time delay neural network method. A time delay neural network with low-complexity high-order architecture, called a “pi-sigma network”, is successfully used to predict scene changes. The proposed dynamic bandwidth allocation scheme is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic with guaranteed quality of services","Title: Utility Max-Min Flow Control Using Slope-Restricted Utility Functions\nYear: 2005\n\nAbstract: We present a network architecture for the distributed utility max-min flow control of elastic and nonelastic flows where utility values of users (rather than data rates of users) are enforced to achieve max-min fairness. The proposed link algorithm converges to utility max-min fair bandwidth allocation in the presence of round-trip delays without using the information of users' utility functions. To show that the proposed algorithm can be stabilized not locally but globally, we found that the use of nonlinear control theory is inevitable. Even though we use a distributed flow-control algorithm, it is shown that any kind of utility function can be used as long as the minimum slopes of the functions are greater than a certain positive value. Though our analysis is limited to the single-bottleneck and homogeneous-delay case, we believe that the proposed algorithm is the first to achieve utility max-min fairness with guaranteed stability in a distributed manner","Title: Research challenges towards the Future Internet\nYear: 2011\n\nAbstract: The convergence of computer-communication networks towards an all-IP integrated network has transformed Internet in a commercial commodity that has stimulated an un-precedent offer of novel communication services that are pushing the Internet architecture and protocols well beyond their original design. This calls for extraordinary research efforts at all levels of the protocol stack to address the challenges of existing and future networked applications and services in terms of scalability, mobility, flexibility, security, etc. In this article we focus on some hot research areas and discuss the research issues that need to be tackled for addressing the multiple challenges of the Future Internet. Far from being a comprehensive analysis of all the challenges faced by the Future Internet, this article tries to call the attention of Computer Communications readers to new and promising research areas, identified by members of the journal editorial board to stimulate further research activities in these areas. The survey of these research areas is then complemented with a brief review of the on-going activities in the other important research areas towards the Future Internet.","Title: Combined packet scheduling and call admission control with minimum throughput guarantee in wireless networks\nYear: 2007\n\nAbstract: In this paper, a scheduling problem is considered in the cellular network where there exist CBR (constant bit rate) users requiring exact minimum average throughput guarantee, and EMG (elastic with minimum guarantee) users requiring minimum average throughput guarantee and more if possible. We propose a combined scheduling and call admission control algorithm that exactly guarantees the minimum requirements of CBR and EMG users, and then allocates the leftover capacity to EMG users. The proposed algorithm is developed using utility maximization problem without minimum throughput constraints and newly defined utility functions. In the algorithm, it is easy to give priority to particular users so that their requirements are guaranteed prior to any other user. Moreover, the priority structure enables the proposed measurement-based call admission control algorithm to perform admission trial without affecting the minimum required throughput of ongoing users. We verify the performance of our algorithm through mathematical analysis and simulations.","Title: Spatial Resource Reuse in the Multi-Hop Cellular Networks: Difficulties and Benefits\nYear: 2008\n\nAbstract: The introduction of relays into legacy cellular networks is gaining more of an interest in the 4th generation (4G) wireless systems. In the presence of relays, simultaneous transmission of both base stations (BS) and relay stations (RS) on the same resources is possible, and consequently much higher throughput can be achieved. However, determining the set of links which will be turned on at the same time is usually considered a NP-complete combinatorial problem. Moreover, it requires cooperation between BSs and RSs of independent cells. In such context, we briefly address the difficulties of spatial resource reuse from the graph-theoretical perspective. Next, our focus shifts to developing a simple but efficient radio resource management algorithm which enables the spatial resource reuse, the pricing-based radio resource management (PRRM) strategy. The PRRM performs spatial reuse for interference-free users operating in the high signal-to-interference-and-noise ratio (SINR) region, while guaranteeing the signal quality of interference-susceptible users usually located near the coverage boundary. By applying the PRRM, we evaluate the potential benefits of the spatial resource reuse.","Title: (Sigma,Rho)-Characterization Based Connection Control For Guaranteed Services In High Speed Networks\nYear: 1995\n\nAbstract: In this paper we present a method to establish real-time connections with guaranteed qualityof-services, based on per-session (oe; ae)-characterization. Under two distinctive service disciplines,rate proportional processor sharing and fixed rate processor sharing, we derive tighter probabilisticbounds on per-session end-to-end average cell loss rate, which is caused by either buffer overflowin the route or excessive delay at the destination. One remarkable feature of the boundingsolutions ...","Title: Greening Effect of Spatio-Temporal Power Sharing Policies in Cellular Networks with Energy Constraints.\nYear: 2012\n\nAbstract: Greening effect in interference management (IM), a way of enhancing spectrum sharing via intelligent transmit power control, can be achieved by the fact that as BSs moderately reduce their transmit powers, the performance degradation decreases slower than linearly, yet a considerable overall energy saving is expected due to transmit powers' exerting influence on operational power. This paper inves...","Title: Flow control with processing constraint\nYear: 2005\n\nAbstract: In this letter we re-examine flow control issues for a network environment where transmission links and CPUs on a data path can be jointly bottlenecked. We show that flow control without consideration of CPU congestion can significantly lose both fairness and efficiency in this environment. As a solution to this problem, we establish the notion of dual-resource propor- tional fairness, propose a distributed algorithm to achieve this objective and demonstrate its performance through simulations.","Title: Detection of DDoS traffic by using the technical analysis used in the stock market\nYear: 2009\n\nAbstract: We propose a method for detecting Distributed Denial of Service (DDoS) traffic in real-time inside the network. For this purpose, we borrow the concepts of Moving Average Convergence Divergence, Rate of Change, and Relative Strength Index, which are used for technical analysis in the stock market. Due to the fact that the method is based on a quantitative, rather than a heuristic, detection level, DDoS traffic can be detected with greater accuracy (by reducing the false alarm ratio). Through detection algorithm and simulation results, we show how the detection level is determined and demonstrate the degree to which the accuracy of detection is enhanced.","Title: QoS Scheduling for Heterogeneous Traffic in OFDMA-Based Wireless Systems\nYear: 2009\n\nAbstract: In this paper, we propose a scheduling framework for heterogeneous traffic in OFDMA-based wireless systems. The proposed scheduling algorithm not only satisfies the QoS requirements of the real-time traffic but also maximizes the utility of the non real-time traffic. Step-by-step approach is used to achieve these two objectives simultaneously with low complexity and traffic class prioritization. A well-known bipartite matching algorithm and a standard gradient scheduling algorithm are adopted for the QoS scheduling of the real-time traffic and for the utility maximization scheduling of the non real-time traffic, respectively. Moreover, a noble beta deadline parameter is introduced to control the balance between the QoS provisioning and the diversity gain. Extensive simulation results in various scenarios are provided to demonstrate the good features of our scheduling framework.","Title: Max-Contribution: On Optimal Resource Allocation in Delay Tolerant Networks\nYear: 2010\n\nAbstract: This is by far the first paper considering joint optimization of link scheduling, routing and replication for disruption-tolerant networks (DTNs). The optimization problems for resource allocation in DTNs are typically solved using dynamic programming which requires knowledge of future events such as meeting schedules and durations. This paper defines a new notion of optimality for DTNs, called snapshot optimality where nodes are not clairvoyant, i.e., cannot look ahead into future events, and thus decisions are made using only contemporarily available knowledge. Unfortunately, the optimal solution for snapshot optimality still requires solving an NP-hard problem of maximum weight independent set and a global knowledge of who currently owns a copy and what their delivery probabilities are. This paper presents a new efficient approximation algorithm, called Distributed Max-Contribution (DMC) that performs greedy scheduling, routing and replication based only on locally and contemporarily available information. Through a simulation study based on real GPS traces tracking over 4000 taxies for about 30 days in a large city, DMC outperforms existing heuristically engineered resource allocation algorithms for DTNs.","Title: Stabilized Edge-to-Edge Aggregate Flow Control\nYear: 2004\n\nAbstract: In this paper, we present a distributed flow control scheme which achieves weighted max-min fair bandwidth allocation among all source-destination pairs on a per-aggregate basis within its network. The motivation behind the scheme is the absence of per-aggregate flow control in the current Internet, resulting in inability to enforce a certain fairness on source-destination flows. In our scheme, the distributed algorithm to compute weighted max-min fair rates is based on PI control in feedback control theory. We mathematically prove the asymptotic stability of the algorithm in presence of aggregate flows with heterogeneous round-trip delays. Through simulations we demonstrate the effectiveness of the proposed scheme in controlling per-aggregate flows.","Title: Fundamental limits of input rate control in high speed network\nYear: 1993\n\nAbstract: The fundamental limits of input rate control by specific analysis in the frequency domain are explored. Both deterministic and stochastic analyses are developed. The simple deterministic analysis helps provide knowledge about the performance tradeoff for input rate control in a high-speed network","Title: Power allocation policies with full and partial inter-system channel state information for cognitive radio networks\nYear: 2013\n\nAbstract: This paper investigates several power allocation policies in orthogonal frequency division multiplexing -based cognitive radio networks under the different availability of inter-system channel state information (CSI) and the different capability of licensed primary users (PUs). Specifically, we deal with two types of PUs having different capabilities: a dumb (peak interference-power tolerable) PU and a more sophisticated (average interference-power tolerable) PU. For such PU models, we first formulate two optimization problems that maximize the capacity of unlicensed secondary user (SU) while maintaining the quality of service of PU under the assumption that both intra- and inter-system CSI are fully available. However, due to loose cooperation between SU and PU, it may be difficult or even infeasible for SU to obtain the full inter-system CSI. Thus, under the partial inter-system CSI setting, we also formulate another two optimization problems by introducing interference-power outage constraints. We propose optimal and efficient suboptimal power allocation policies for these four problems. Extensive numerical results demonstrate that the spectral efficiency achieved by SU with partial inter-system CSI is less than half of what is achieved with full inter-system CSI within a reasonable range of outage probability (e.g., less than 10 %). Further, it is shown that the average interference-power tolerable PU can help to increase the saturated spectral efficiency of SU by about 20 and 50 % in both cases of full and partial inter-system CSI, respectively.","Title: Experimental evaluation of optimal CSMA\nYear: 2011\n\nAbstract: By `optimal CSMA' we denote a promising approach to maximize throughput-based utility in wireless networks without message passing or synchronization among nodes. Despite the theoretical guarantees on the performance of these protocols, their evaluation in real networking scenarios has been preliminary. In this paper, we propose a methodical approach for the first comprehensive evaluation of optimal CSMA, via experimentation with a custom implementation. Example findings include; 1) hidden terminals with symmetric channels can drive the protocol to a state of extreme contention aggressiveness due to the low service received by flows. Since increasing aggressiveness does not mitigate collisions but actually aggravates them, optimal CSMA enters a positive-feedback loop eventually reaching a deadlock state of total flow starvation; 2) however, the use of RTS/CTS in such scenarios can reduce collisions to lower levels, restoring throughput and preventing an excessive contention aggressiveness by optimal CSMA flows; 3) in practical hidden terminal scenarios with physical layer capture optimal CSMA reduces the aggressiveness of dominant flows, but the contention window sizes used by such adaptation mechanism are not long enough to solve competing flows' starvation when carrier sensing fails; 4) topologies with a “flow-in-the-middle” yield starvation in traditional CSMA but fairness in optimal CSMA, because its contention aggressiveness adaptation creates frequent transmission opportunities for the central (otherwise starved) flow; 5) optimal CSMA excessively prioritizes links with low channel quality, due to queue-based control that does not otherwise incorporate channel conditions; 6) in its current design, optimal CSMA conflicts with window-based end-to-end congestion control, and leads to a efficiency-fairness tradeoff in TCP performance. This study deepens our understanding of optimal CSMA and the general adaptation philosophy behind its design, and - - the derived insights suggest enhancements to optimal CSMA theory.","Title: Opportunistic Relaying in Cellular Network for Capacity and Fairness Improvement\nYear: 2007\n\nAbstract: In this paper, we study how the cooperative relaying can improve both capacity and fairness in cellular network. The capacity and fairness have a trade-off relationship, so increasing cell throughput deteriorates fairness and vice versa. First, we show that the achievable average throughput region can be enlarged by using the cooperative relaying. This enlarged region means that capacity and fairness can be improved at the same time with an adequate scheduling algorithm. Thus, secondly we propose a generalized scheduling algorithm for cooperative relaying. The proposed scheduling algorithm can improve both capacity and fairness at the expense of cooperation among users. From simulations, we show that the trade-off relationship can be surpassed and the unfairness problem in the heterogeneous channel condition can be solved by the opportunistic relaying.","Title: A TCP starvation problem in combining TCP and max-weight scheduling of cross-layer algorithms in WMNs\nYear: 2009\n\nAbstract: In this paper, we investigate the problem coming from the adaptation of legacy protocol TCP to the cross-layer protocols that is likely happen in future Internet. We point out named a TCP starvation problem in combining TCP and max-weight scheduling of cross-layer algorithms in wireless mesh networks. TCP starvation occurs when neighbor nodes are already scheduled with large queue length. To overcome TCP starvation as denoted in this paper, we propose a simple remedy named fake-ACK algorithm.","Title: Two-Hop Opportunistic Scheduling in Cooperative Cellular Networks\nYear: 2012\n\nAbstract: Due to the tradeoff between capacity and fairness in a wide variety of networks, increasing one objective may deteriorate the other. This paper investigates the possibility of improving capacity and fairness at the same time, specifically in two-hop cellular networks. First, we prove that an achievable capacity region can be enlarged by using relay, i.e., the capacity and fairness tradeoff relationship is alleviated. To achieve the Pareto-efficient boundary of this enlarged capacity region, an appropriate scheduling algorithm should be developed. Thus, second, we propose a generalized opportunistic scheduling algorithm for relaying mode that can improve both capacity and fairness. Furthermore, we propose a heuristic algorithm with low complexity and signaling overhead for relaying mode. Extensive simulations under various configurations demonstrate that the proposed algorithm not only increases the throughput of each user but also effectively alleviates unfairness among users.","Title: Scheduling and Source Control with Average Queue-Length Control in Cellular Networks\nYear: 2007\n\nAbstract: In this paper, a scheduling problem is considered in the cellular network where there exist CBR (constant bit rate) users requiring exact minimum average throughput and delay guarantee, and EMG (elastic with minimum guarantee) users requiring minimum average throughput and delay guarantee and more throughput if possible. We first define a new utility function of average queue length. Based on the new queue utility function and the throughput utility function proposed before, we design a 2-dimensional weight function that will be used in our scheduling algorithm, and suggest a source control algorithm that can work with the scheduling algorithm. We show through simulations that the proposed algorithm guarantees the QoS (quality of service) requirements of CBR and EMG users.","Title: Commoncode: a code-reuse platform for wireless network experimentation\nYear: 2012\n\nAbstract: Experimentation of a wireless network protocol over the air is of significant interest. However, it is more rarely performed than simulation because of the difficulties in coding and debugging as well as lack of scalability and repeatability. In this article, the concept of a code-reuse platform making use of a simulation code directly for real experiments is revisited as an efficient and easy means of experimentation. Furthermore, an architecture and key components of an idealistic code-reuse platform are suggested, and then CommonCode, the most advanced codereuse platform, is proposed. Through extensive simulations and experiments using Common-Code for the same codes, we demonstrate that CommonCode is valid and accurate in terms of protocol performance, and simultaneously fast and easy in terms of protocol development.","Title: Dynamic bandwidth allocation schemes to improve utilization under nonuniform traffic in Ethernet passive optical networks\nYear: 2004\n\nAbstract: In this paper, conventional bandwidth allocation schemes in ethernet passive optical network (EPON) are shown to suffer from poor utilization under the nonuniform traffic, particularly as the number of ONUs, guard time and round-trip time increase. To resolve this problem, we propose a new scheme which intelligently allocates a timeslot in consideration of other ONUs' queue occupancy, instead of strictly enforcing maximum timeslot size. The analysis and simulation results show that the proposed scheme can provide significantly higher utilization than the conventional schemes and support max-min fairness under the nonuniform traffic.","Title: Predictive dynamic bandwidth allocation for efficient transport of real-time VBR video over ATM\nYear: 1995\n\nAbstract: This paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. Video traffic statistics are measured in the frequency domain. The low-frequency signal captures the slow time-variation of consecutive scene changes while the high-frequency signal exhibits the feature of strong frame autocorrelation. Our queueing study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low-frequency signal. We further observe in typical JPEG/MPEG video sequences that the time scale of video scene changes is in the range of a second or longer, which localizes the low-frequency video signal in a well-defined low-frequency band. Hence, in a network design it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: recursive least square method and time delay neural network method. A time delay neural network with low-complexity high-order architecture, called “pi-sigma network,” is successfully used to predict scene changes. The overall dynamic bandwidth-allocation scheme presented is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic","Title: Improving TCP Performance over Optimal CSMA in Wireless Multi-Hop Networks\nYear: 2012\n\nAbstract: Optimal CSMA (oCSMA) has been receiving extensive attentions for its provable optimality in throughput and fairness without message passing over wireless multi-hop networks. However, recent studies suggest that TCP over oCSMA performs poorly, hindering the deployment of oCSMA in real networks. In this letter, we show that just a simple, additional virtual queue at the MAC layer can significantly improve TCP performance when oCSMA is used as the underlying MAC. Through testbed-based experiments, we demonstrate that with our virtual queueing scheme, TCP flows achieve near-optimal throughput performance in various scenarios.","Title: Distributed max-min flow control for multi-rate overlay multicast\nYear: 2010\n\nAbstract: We present a distributed algorithm to compute bandwidth max–min fair rates in an overlay multicast network supporting multi-rate data delivery. The proposed algorithm is scalable in that it does not require each logical link to maintain the saturation status of all sessions and virtual sessions traveling through it, stable in that it converges asymptotically to the desired equilibrium satisfying the minimum plus max–min fairness even in the presence of heterogeneous round-trip delays, and has explicit link buffer control in that the buffer occupancy of every bottlenecked link in the network asymptotically converges to the pre-defined value. The algorithm is based on PI (proportional integral) control in the feedback control theory and by appealing to the Nyquist stability criterion, a usable stability condition is derived in the presence of sources with heterogeneous round-trip delays. In addition, we propose an efficient feedback consolidation algorithm which is computationally simpler than its hard-synchronization based counterpart and eliminates unnecessary consolidation delay by preventing it from awaiting backward control packets that do not directly contribute to the session rate. Through simulations we further verify the analytical results and the performance of the proposed multi-rate multicast flow control scheme based on these two algorithms.","Title: Dynamic association for load balancing and interference avoidance in multi-cell networks\nYear: 2007\n\nAbstract: Next-generation cellular networks will provide higher cell capacity by adopting advanced physical layer techniques and broader bandwidth. Even in such networks, boundary users would suffer from low throughput due to severe intercell interference and unbalanced user distributions among cells, unless additional schemes to mitigate this problem are employed. In this paper, we tackle this problem by jointly optimizing partial frequency reuse and load-balancing schemes in a multicell network. We formulate this problem as a network-wide utility maximization problem and propose optimal offline and practical online algorithms to solve this. Our online algorithm turns out to be a simple mixture of inter- and intra-cell handover mechanisms for existing users and user association control and cell-site selection mechanisms for newly arriving users. A remarkable feature of the proposed algorithm is that it uses a notion of expected throughput as the decision making metric, as opposed to signal strength in conventional systems. Extensive simulations demonstrate that our online algorithm can not only closely approximate network-wide proportional fairness but also provide two types of gain, interference avoidance gain and load balancing gain, which yield 20~100% throughput improvement of boundary users (depending on traffic load distribution), while not penalizing total system throughput.We also demonstrate that this improvement cannot be achieved by conventional systems using universal frequency reuse and signal strength as the decision making metric.","Title: Feedback Reduction for Multiuser OFDM Systems\nYear: 2010\n\nAbstract: Feedback reduction in multiuser orthogonal frequency-division multiplexing (OFDM) systems has become an important issue due to the excessive amount of feedback required to use opportunistic scheduling, particularly when the number of users and carriers is large. In this paper, we propose a novel feedback-reduction scheme for efficient downlink scheduling. In the proposed scheme, each user determin...","Title: Feedback Reduction for Multiuser OFDM Systems\nYear: 2010\n\nAbstract: Feedback reduction in multiuser orthogonal frequency-division multiplexing (OFDM) systems has become an important issue due to the excessive amount of feedback required to use opportunistic scheduling, particularly when the number of users and carriers is large. In this paper, we propose a novel feedback-reduction scheme for efficient downlink scheduling. In the proposed scheme, each user determin...","Title: Probabilistic burstiness-curve-based connection control for real-time multimedia services in ATM networks\nYear: 1997\n\nAbstract: In this paper we present a method to establish real-time connections with guaranteed quality of service (QOS), based on a per-session probabilistic burstiness curve (PBC). Under two distinctive service disciplines, role proportional processor sharing and fixed rate processor sharing, we derive useful probabilistic bounds on per-session end-to-end loss which is caused by either buffer overflow in the path or excessive delay to the destination. One remarkable feature of the bounding solutions is that they are solely determined by the PBC of each session itself, independent of the network environment and other connections. To improve network resource utilization, our method is extended to allow statistical sharing of buffer resources. The admission control scheme presented in this paper has a great flexibility in connection management since bandwidth and buffer allocations can be adaptively adjusted among incoming and existing sessions according to present network resource availability. We also present a novel method to compute the PBC of multimedia traffic based on the measurement of two important statistics (rate histogram and power spectrum). Our study of MPEG/JPEG video sequences reveals the fundamental interrelationship among the PBC, the traffic statistics, and the QOS guarantee, and also provides many engineering aspects of the PBC approach to real-time multimedia services in ATM networks","Title: Energy-optimal collaborative GPS localization with short range communication\nYear: 2013\n\nAbstract: The key issue of the localization study is that how we can minimize the energy consumption of devices with guaranteeing high degree of accuracy. In this paper, we show that the collaboration among proxy devices with short range communication is helpful to energy-efficiently localize their locations in time-average sense by analyzing the device proximity including real GPS trace of students in KAIST and NCSU campuses. Next, we deliberate what is the best method for selfish mobile users to collaborate for the energy-efficient localization, and formulate an optimization problem which considers the energy efficiency and/or user fairness. However, optimizing this problem is tricky since it requires a global knowledge of sets of proxy devices and also solving a NP-hard problem to select devices which directly measure locations. This paper makes a contribution towards presenting a practical and fully distributed location sharing protocol based on competition for turning off GPS, and an optimal algorithm which controls mean waiting time used for the competition. Through the extensive simulations under several sample topologies and real mobility trace in KAIST campus, we obtain the following interesting observations: (i) (in sample topologies) our scheme achieves a near-optimal performance of proposed problem in terms of energy efficiency and fairness (up to 27.2% power saving with 35.8% higher fairness than existing heuristic algorithms), (ii) (in real mobility trace) our scheme well adapts at even unpredictably changing mobility environment (65.5% power saving than no collaboration, 27.4% or more power saving with 25% higher fairness than the existing algorithms).","Title: WiOpt - general chair's message.\nYear: 2009\n\nAbstract: Welcome to Seoul and welcome to the Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), the intellectual hub and melting pot of ideas from researchers and ractitioners interested in all aspects of modeling and optimization of wireless communication, ad hoc and mobile networking.","Title: Wi-Fi sensing: Should mobiles sleep longer as they age?\nYear: 2013\n\nAbstract: An essential condition precedent to the success of mobile applications based on Wi-Fi (e.g., iCloud) is an energy-efficient Wi-Fi sensing. From a user's perspective, a good WiFi sensing policy should depend on both inter-AP arrival and contact duration time distributions. Prior work focuses on limited cases of those two distributions (e.g., exponential) or introduces heuristic approaches such as AI (Additive Increase). In this paper, we formulate a functional optimization problem on Wi-Fi sensing under general inter-AP and contact duration distributions, and propose how each user should sense Wi-Fi APs to strike a balance between energy efficiency and performance, depending on the users' mobility pattern. To that end, we derive an optimal condition which sheds insights into the aging property, the key feature required by efficient Wi-Fi sensing polices. Guided by the analytical studies and the implications, we develop a new sensing algorithm, called WiSAG (Wi-Fi Sensing with AGing), which is demonstrated to outperform the existing sensing algorithms up to 34% through extensive trace-driven simulations using the real mobility traces gathered from smartphones.","Title: Opportunistic underlay transmission in multi-carrier cognitive radio systems\nYear: 2009\n\nAbstract: Underlay transmission in cognitive radio enables a secondary (unlicensed) system to utilize a frequency band of primary (licensed) system as long as the unlicensee interferes less than a certain threshold with the licensee. The secondary system needs to carefully consider not only its own channel to achieve a capacity gain by this sharing spectrum in multi-carrier systems, but also the interference channel to reduce interference at the primary receiver. In this paper, we formulate a capacity maximization problem of the secondary system under an interference-power constraint as well as a conventional transmit-power constraint, and propose an optimal power allocation policy in which we exploit a two-dimensional frequency-selectivity on both channels. Through extensive simulations, we compare the performance of optimal power allocation policy with that of equal power allocation policy and further investigate the effect of the primary's power allocation policy on the performance of the secondary system. Numerical results show that the optimal power allocation policy can achieve a higher capacity in more frequency-selective channels, compared to an equal power allocation policy. Interestingly, a water-filling policy for the primary system also gives additional opportunities to the secondary system than the equal power allocation policy.","Title: Dual-Resource TCP/AQM for Processing-Constrained Networks\nYear: 2008\n\nAbstract: This paper examines congestion control issues for TCP flows that require in-network processing on the fly in network elements such as gateways, proxies, firewalls and even routers. Applications of these flows are increasingly abundant in the future as the Internet evolves. Since these flows require use of CPUs in network elements, both bandwidth and CPU resources can be a bottleneck and thus congestion control must deal with ldquocongestionrdquo on both of these resources. In this paper, we show that conventional TCP/AQM schemes can significantly lose throughput and suffer harmful unfairness in this environment, particularly when CPU cycles become more scarce (which is likely the trend given the recent explosive growth rate of bandwidth). As a solution to this problem, we establish a notion of dual-resource proportional fairness and propose an AQM scheme, called Dual-Resource Queue (DRQ), that can closely approximate proportional fairness for TCP Reno sources with in-network processing requirements. DRQ is scalable because it does not maintain per-flow states while minimizing communication among different resource queues, and is also incrementally deployable because of no required change in TCP stacks. The simulation study shows that DRQ approximates proportional fairness without much implementation cost and even an incremental deployment of DRQ at the edge of the Internet improves the fairness and throughput of these TCP flows. Our work is at its early stage and might lead to an interesting development in congestion control research.","Title: On the Critical Delays of Mobile Networks Under Lévy Walks and Lévy Flights\nYear: 2011\n\nAbstract: Delay-capacity tradeoffs for mobile networks have been analyzed through a number of research works. However, Lévy mobility known to closely capture human movement patterns has not been adopted in such work. Understanding the delay-capacity tradeoff for a network with Lévy mobility can provide important insights into understanding the performance of real mobile networks governed by human mobility. This paper analytically derives an important point in the delay-capacity tradeoff for Lévy mobility, known as the critical delay. The critical delay is the minimum delay required to achieve greater throughput than what conventional static networks can possibly achieve (i.e., O(1/√n) per node in a network with n nodes). The Lévy mobility includes Lévy flight and Lévy walk whose step-size distributions parametrized by α ∈ (0,2] are both heavy-tailed while their times taken for the same step size are different. Our proposed technique involves: 1) analyzing the joint spatio-temporal probability density function of a time-varying location of a node for Lévy flight, and 2) characterizing an embedded Markov process in Lévy walk, which is a semi-Markov process. The results indicate that in Lévy walk, there is a phase transition such that for α ∈ (0,1), the critical delay is always Θ(n[1/2]), and for α ∈ [1,2] it is Θ(n[(α)/2]). In contrast, Lévy flight has the critical delay Θ(n[(α)/2]) for α ∈ (0,2].","Title: Capacity of interference-limited ad hoc networks with infrastructure support\nYear: 2006\n\nAbstract: In this letter, we consider the capacity of ad hoc networks with infrastructure support. Although Grossglauser-Tse mobile network model enables /spl Theta/(1) per-node throughput scaling, the mobility assumption may be too unrealistic to be accepted in some practical situations. One of the key observations we acquired is that the infrastructure support plays the same role played by the mobility in the Grossglauser-Tse model. We show that nodes can utilize the randomly located infrastructure support instead of mobility when nodes are nearly static. In this case, we show that the per-node throughput of /spl Theta/(1) is still achievable when the number of access points grows linearly with respect to the number of nodes.","Title: Delay-optimal data forwarding in Vehicular Sensor Networks\nYear: 2013\n\nAbstract: Vehicular Sensor Network (VSN) is emerging as a new solution for monitoring urban environments such as Intelligent Transportation Systems and air pollution. One of the crucial factors that determine the service quality of urban monitoring applications is the delivery delay of sensing data packets in the VSN. In this paper, we study the problem of routing data packets with minimum delay in the VSN, by exploiting i) vehicle traffic statistics, ii) anycast routing and iii) knowledge of future trajectories of vehicles such as buses. We first introduce a novel road network graph model that incorporates the three factors into the routing metric. We then characterize the packet delay on each edge as a function of the vehicle density, speed and the length of the edge. Based on the network model and delay function, we formulate the packet routing problem as a Markov Decision Process (MDP) and develop an optimal routing policy by solving the MDP. Evaluations using real vehicle traces in a city show that our routing policy significantly improves the delay performance compared to existing routing protocols.","Title: Economics of WiFi offloading: Trading delay for cellular capacity\nYear: 2013\n\nAbstract: Cellular networks are facing severe traffic overloads due to the proliferation of smart handheld devices and traffic-hungry applications. A cost-effective and practical solution is to offload cellular data through WiFi. Recent theoretical and experimental studies show that a scheme, referred to as delayed WiFi offloading, can significantly save the cellular capacity by delaying users' data and exploiting mobility and thus increasing chance of meeting WiFi APs (Access Points). Despite a huge potential of WiFi offloading in alleviating mobile data explosion, its success largely depends on the economic incentives provided to users and network providers to deploy and use delayed offloading. In this paper, we study how much economic benefits can be generated due to delayed WiFi offloading, by modeling the interaction between a single provider and users based on a two-stage sequential game. We first analytically prove that WiFi offloading is economically beneficial for both the provider and users. Also, we conduct trace-driven numerical analysis to quantify the practical gain, where the increase ranges from 21 to 152% in the provider's revenue, and from 73 to 319% in the users' surplus.","Title: Delay-capacity tradeoffs for mobile networks with Lévy walks and Lévy flights\nYear: 2011\n\nAbstract: This paper analytically derives the delay-capacity tradeoffs for Lévy mobility: Lévy walks and Lévy flights. Lévy mobility is a random walk with a power-law flight distribution. α is the power-law slope of the distribution and 0 <;; α ≤ 2. While in Lévy flight, each flight takes a constant flight time, in Lévy walk, it has a constant velocity which incurs strong spatio-temporal correlation as flight time depends on traveling distance. Lévy mobility is of special interest because it is known that Lévy mobility and human mobility share several common features including heavy-tail flight distributions. Humans highly influence the mobility of nodes (smartphones and cars) in real mobile networks as they carry or drive mobile nodes. Understanding the fundamental delay-capacity tradeoffs of Lévy mobility provides important insight into understanding the performance of real mobile networks. However, its power-law nature and strong spatio-temporal correlation make the scaling analysis non-trivial. This is in contrast to other random mobility models including Brownian motion, random waypoint and i.i.d. mobility which are amenable for a Markovian analysis. By exploiting the asymptotic characterization of the joint spatio-temporal probability density functions of Lévy models, the order of critical delay, the minimum delay required to achieve more throughput than Θ(1/√n) where n is the number of nodes in the network, is obtained. The results indicate that in Lévy walk, there is a phase transition that for 0 <; α <; 1, the critical delay is constantly Θ(n1/2) and for 1 ≤ α ≤ 2, is Θ(nα/2). In contrast, Lévy flight has critical delay Θ(nα/2) for 0 <; α ≤ 2.","Title: A Video Traffic Model Based on the Shifting-Level Process: the Effects of SRD and LRD on Queueing Behavior\nYear: 2000\n\nAbstract: Recently, a number of empirical studies havedemonstrated the existence of long-range dependence(LRD) or self-similarity in VBR video traffic. Since previousLRD models cannot capture all short- and long-term correlationand rate-distribution while still retaining mathematicaltractability, there exist many doubts on the importanceof SRD, LRD, and rate-distribution on traffic engineering.In this paper, we present a video traffic model basedon the shifting-level (SL) process with an...","Title: Designing stable ABR flow control with rate feedback and open-loop control: first-order control case\nYear: 1998\n\nAbstract: In this paper we present a control-theoretic approach to design stable rate-based flow control for ATM ABR services. The flow control algorithm that we consider has the most simple form among all the queue-length-based flow control algorithms, and is referred to as first-order rate-based flow control (FRFC) since the corresponding closed loop can be modeled as a first-order retarded differential equation. We analyze the equilibrium and the asymptotic stability of the closed loop for the case of multiple connections with diverse round-trip delays. We also characterize the asymptotic decay rate at which the stable closed loop tends to the equilibrium. The decay rate is shown to be a concave function of control gain with its maximum being the inverse of round-trip delay. We also consider an open loop control in which the queue control threshold is dynamically adjusted according to the changes in the available bandwidth and the number of connections. This open loop control is shown to be necessary and effective to prevent the closed loop from converging to an undesirable equilibrium point.","Title: REFIM: A Practical Interference Management in Heterogeneous Wireless Access Networks\nYear: 2011\n\nAbstract: Due to the increasing demand of capacity in wireless cellular networks, the small cells such as pico and femto cells are becoming more popular to enjoy a spatial reuse gain, and thus cells with different sizes are expected to coexist in a complex manner. In such a heterogeneous environment, the role of interference management (IM) becomes of more importance, but technical challenges also increase,...","Title: Routing performance analysis of human-driven delay tolerant networks using the truncated levy walk model\nYear: 2008\n\nAbstract: The routing performance of delay tolerant networks (DTN) is highly correlated with the distribution of inter-contact times (ICT), the time period between two successive contacts of the same two mobile nodes. As humans are often carriers of mobile communication devices, studying the patterns of human mobility is an essential tool to understand the performance of DTN protocols. From measurement studies of human contact behaviors, we find that their distributions closely resemble a form of power-law distributions called truncated Pareto. Human walk traces has a dichotomy distribution pattern of ICT; it has a power-law tendency up to some time, and decays exponentially after that time. Truncated Pareto distributions offer a simple yet cohesive mathematical model to express this dichotomy in the measured data. Using the residual and relaxation time theory [17] [4], we apply truncated Pareto distributions to quantify the performance of opportunistic routing in DTN. We further show that Truncated Levy walk (TLW) mobility model [22] commonly used in biology to describe the foraging patterns of animals [25], provide the same truncated power-law ICT distributions as observed from the empirical data, especially when mobility is confined within a finite area. This result confirms our recent finding that human walks contain similar statistical characteristics as Levy walks [22].","Title: TCP-friendly flow control of wireless multimedia using ECN marking\nYear: 2004\n\nAbstract: In a wireless network packet losses can be caused not only by network congestion but also by unreliable error-prone wireless links. Therefore, flow control schemes which use packet loss as a congestion measure cannot be directly applicable to a wireless network because there is no way to distinguish congestion losses from wireless losses. In this paper, we extend the so-called TCP-friendly flow control scheme, which was originally developed for the flow control of multimedia flows in a wired IP network environment, to a wireless environment. The main idea behind our scheme is that by using explicit congestion notification (ECN) marking in conjunction with random early detection (RED) queue management scheme intelligently, it is possible that not only the degree of network congestion is notified to multimedia sources explicitly in the form of ECN-marked packet probability but also wireless losses are hidden from multimedia sources. We calculate TCP-friendly rate based on ECN-marked packet probability instead of packet loss probability, thereby effectively eliminating the effect of wireless losses in flow control and thus preventing throughput degradation of multimedia flows travelling through wireless links. In addition, we refine the well-known TCP throughput model which establishes TCP-friendliness of multimedia flows in a way that the refined model provides more accurate throughput estimate of a TCP flow particularly when the number of TCP flows sharing a bottleneck link increases. Through extensive simulations, we show that the proposed scheme indeed improves the quality of the delivered video significantly while maintaining TCP-friendliness in a wireless environment for the case of wireless MPEG-4 video.","Title: On the Levy-Walk Nature of Human Mobility\nYear: 2011\n\nAbstract: We report that human walk patterns contain statistically similar features observed in Levy walks. These features include heavy-tail flight and pause-time distributions and the super-diffusive nature of mobility. Human walks are not random walks, but it is surprising that the patterns of human walks and Levy walks contain some statistical similarity. Our study is based on 226 daily GPS traces collected from 101 volunteers in five different outdoor sites. The heavy-tail flight distribution of human mobility induces the super-diffusivity of travel, but up to 30 min to 1 h due to the boundary effect of people's daily movement, which is caused by the tendency of people to move within a predefined (also confined) area of daily activities. These tendencies are not captured in common mobility models such as random way point (RWP). To evaluate the impact of these tendencies on the performance of mobile networks, we construct a simple truncated Levy walk mobility (TLW) model that emulates the statistical features observed in our analysis and under which we measure the performance of routing protocols in delay-tolerant networks (DTNs) and mobile ad hoc networks (MANETs). The results indicate the following. Higher diffusivity induces shorter intercontact times in DTN and shorter path durations with higher success probability in MANET. The diffusivity of TLW is in between those of RWP and Brownian motion (BM). Therefore, the routing performance under RWP as commonly used in mobile network studies and tends to be overestimated for DTNs and underestimated for MANETs compared to the performance under TLW.","Title: First-order rate-based flow control with dynamic queue threshold for high-speed wide-area ATM networks.\nYear: 1998\n\nAbstract: In this paper we present a new rate-based flow control scheme for ATM ABR services and analyze its performance. The proposed algorithm, which we refer to as first-order rate-based flow control (FRFC) is the most simple form of queue-length-based flow control. The asymptotic stability, the steady-state throughput, queue length and fairness, and the transient behavior are analyzed for the case of multiple connections with diverse round-trip delays. We also consider a novel approach to dynamically adjust a queue threshold in the FRFC according to the changes in the available bandwidth, and the arrival and departure of connections. Simulations show that the simple FRFC with dynamic queue threshold (DQT) effectively maintains high throughput, small loss and a desired fairness in these dynamic environments and is a promising solution for ABR flow control in ATM networks.","Title: SLAW: self-similar least-action human walk\nYear: 2012\n\nAbstract: Many empirical studies of human walks have reported that there exist fundamental statistical features commonly appearing in mobility traces taken in various mobility settings. These include: 1) heavy-tail flight and pause-time distributions; 2) heterogeneously bounded mobility areas of individuals; and 3) truncated power-law intercontact times. This paper reports two additional such features: a) The destinations of people (or we say waypoints) are dispersed in a self-similar manner; and b) people are more likely to choose a destination closer to its current waypoint. These features are known to be influential to the performance of human-assisted mobility networks. The main contribution of this paper is to present a mobility model called Self-similar Least-Action Walk (SLAW) that can produce synthetic mobility traces containing all the five statistical features in various mobility settings including user-created virtual ones for which no empirical information is available. Creating synthetic traces for virtual environments is important for the performance evaluation of mobile networks as network designers test their networks in many diverse network settings. A performance study of mobile routing protocols on top of synthetic traces created by SLAW shows that SLAW brings out the unique performance features of various routing protocols.","Title: CommonCode: a code reuse platform for co-simulation and experimentation\nYear: 2010\n\nAbstract: Experimentation of a wireless network protocol over the air is of significant interest. However it is rarely performed compared to the simulation because of the difficulties in coding and debugging as well as scalability and repeatability. CommonCode is a unique protocol validation platform reusing the simulation codes for the experiments. It helps fast, convenient and accurate validation of protocols.","Title: Mobile Data Offloading: How Much Can WiFi Deliver?\nYear: 2010\n\nAbstract: This paper presents a quantitative study on the performance of 3G mobile data offloading through WiFi networks. We recruited 97 iPhone users from metropolitan areas and collected statistics on their WiFi connectivity during a two-and-a-half-week period in February 2010. Our trace-driven simulation using the acquired whole-day traces indicates that WiFi already offloads about 65% of the total mobile data traffic and saves 55% of battery power without using any delayed transmission. If data transfers can be delayed with some deadline until users enter a WiFi zone, substantial gains can be achieved only when the deadline is fairly larger than tens of minutes. With 100-s delays, the achievable gain is less than only 2%-3%, whereas with 1 h or longer deadlines, traffic and energy saving gains increase beyond 29% and 20%, respectively. These results are in contrast to the substantial gain (20%-33%) reported by the existing work even for 100-s delayed transmission using traces taken from transit buses or war-driving. In addition, a distribution model-based simulator and a theoretical framework that enable analytical studies of the average performance of offloading are proposed. These tools are useful for network providers to obtain a rough estimate on the average performance of offloading for a given WiFi deployment condition.","Title: Mobile data offloading: how much can WiFi deliver?\nYear: 2013\n\nAbstract: This paper presents a quantitative study on the performance of 3G mobile data offloading through WiFi networks. We recruited 97 iPhone users from metropolitan areas and collected statistics on their WiFi connectivity during a two-and-a-halfweek period in February 2010. Our trace-driven simulation using the acquired whole-day traces indicates that WiFi already offloads about 65% of the total mobile data traffic and saves 55% of battery power without using any delayed transmission. If data transfers can be delayed with some deadline until users enter a WiFi zone, substantial gains can be achieved only when the deadline is fairly larger than tens of minutes. With 100-s delays, the achievable gain is less than only 2%-3%, whereas with 1 h or longer deadlines, traffic and energy saving gains increase beyond 29% and 20%, respectively. These results are in contrast to the substantial gain (20%-33%) reported by the existing work even for 100-s delayed transmission using traces taken from transit buses or war-driving. In addition, a distribution model-based simulator and a theoretical framework that enable analytical studies of the average performance of offloading are proposed. These tools are useful for network providers to obtain a rough estimate on the average performance of offloading for a given WiFi deployment condition.","Title: Deterministic packet marking for max-min flow control\nYear: 2005\n\nAbstract: This letter proposes a deterministic packet marking scheme that estimates the maximum link price on a communication path. The proposed scheme is simple and IP-compatible because it uses two-bit explicit congestion notification (ECN) field and IP identification (IPid) field in the standard IP header for the estimation. Through simulations using real IP packet traces, we show that our scheme indeed works as designed with small estimation errors, and thus enables existing max-min flow control algorithms to serve their purpose without the need of separate out-of-band control packets to carry link prices.","Title: Max Contribution: An Online Approximation of Optimal Resource Allocation in Delay Tolerant Networks\nYear: 2015\n\nAbstract: In this paper, a joint optimization of link scheduling, routing and replication for delay-tolerant networks (DTNs) has been studied. The optimization problems for resource allocation in DTNs are typically solved using dynamic programming which requires knowledge of future events such as meeting schedules and durations. This paper defines a new notion of approximation to the optimality for DTNs, called snapshot approximation where nodes are not clairvoyant, i.e., not looking ahead into future events, and thus decisions are made using only contemporarily available knowledges. Unfortunately, the snapshot approximation still requires solving an NP-hard problem of maximum weighted independent set (MWIS) and a global knowledge of who currently owns a copy and what their delivery probabilities are. This paper proposes an algorithm, Max-Contribution (MC) that approximates MWIS problem with a greedy method and its distributed online approximation algorithm, Distributed Max-Contribution (DMC) that performs scheduling, routing and replication based only on locally and contemporarily available information. Through extensive simulations based on real GPS traces tracking over 4,000 taxies and 500 taxies for about 30 days and 25 days in two different large cities, DMC is verified to perform closely to MC and outperform existing heuristically engineered resource allocation algorithms for DTNs.","Title: Virtual Cell Beamforming in Cooperative Networks\nYear: 2014\n\nAbstract: We study the coordinated transmission problem in cooperative cellular networks where a cluster of base stations forms a virtual cell to serve a mobile station (MS). The performance of such an MS-centric virtual cell network is dictated by the beamformer that enables to suppress interference; however, designing a beamformer is highly challenging due to the coupled nature of interference and desired signals under arbitrarily formed virtual cells. We develop a new formulation of the beamforming problem for sum-rate maximization in virtual cell networks and analyze the structure of its optimal solutions. Based on this analysis, we develop a beamforming algorithm that can balance between desired signal maximization and interference minimization, so as to maximize the sum-rate. We show through extensive simulations that our balanced beamforming algorithm mitigates edge user effect and outperforms existing algorithms in various scenarios where virtual cells are allowed to overlap.","Title: Dynamic speed scaling for energy minimization in delay-tolerant smartphone applications\nYear: 2014\n\nAbstract: Energy-delay tradeoffs in smartphone applications have been studied independently in dynamic voltage and frequency scaling (DVFS) problem and network interface selection problem. We optimize the two problems jointly to quantify how much energy can be saved further and propose a scheme called SpeedControl which jointly manages application scheduling, CPU speed control and wireless interface selection. The scheme is shown to be near-optimal in that it tends to minimize energy consumption for given delay constraints. This paper is the first to reveal energy-delay tradeoffs in a holistic view considering multiple wireless interfaces, DVFS and multitasking in smartphone. We perform real measurements on WiFi/3G coverage and throughput, power consumption of CPU and WiFi/3G interfaces, and CPU workloads. Trace-driven simulations based on the measurements demonstrate that SpeedControl can save over 30% of battery by trading 10 min delay as compared to existing schemes when WiFi temporal coverage is 65%, moreover, the saving tendency increases as WiFi coverage increases.","Title: PhonePool: On energy-efficient mobile network collaboration with provider aggregation\nYear: 2014\n\nAbstract: Energy consumption for cellular communication is increasingly gaining importance in smartphone battery lifetime as the bandwidth of wireless communication and the demand for mobile traffic increase. For energy-efficient cellular communication, we tackle two energy characteristics of cellular networks: (1) transmission energy highly varies upon channel condition, and (2) transmission of a packet accompanies unnecessary tail energy waste. Under the objective of transmitting packets when the best channel is provided as well as a number of packets are accumulated, we propose a new mobile collaboration framework “PhonePool” that aggregates smart devices across multiple cellular providers. Compared to the standalone operation, even without a buffering delay, PhonePool allows better channel and reduces more tail energy in a statistical point of view. To maximize the energy benefit while maintaining the fairness among the nodes in collaboration, we further develop a dynamic programming framework providing the optimal algorithm of PhonePool and its approximated heuristic. Trace-driven simulations on our experimental HSPA/EVDO/LTE network traces show that PhonePool of 5 devices achieves up to 42% of energy reduction.","Title: CSMA-Based Robust AP Throughput Guarantee Under User Distribution Uncertainty\nYear: 2015\n\nAbstract: We consider the problem of providing inter-access-point (AP) fairness guarantee in dense AP deployments where starvation can occur. In particular, we develop a framework for providing robust minimum throughput guarantee for each AP under the uncertainty of user distributions. Our framework consists of an AP throughput provisioning scheme and a distributed CSMA algorithm. The throughput provisioning scheme computes a robust feasible minimum AP throughput vector based on a random AP-level conflict graph and chance-constrained optimization. By incorporating the minimum throughput vector, we develop a distributed CSMA algorithm that fulfills the minimum requirement for each AP and is compatible with the IEEE 802.11 standard. We show through extensive simulations that our framework addresses the AP starvation problem by guaranteeing minimum throughput for each AP.","Title: Seamless realtime traffic handover policy for IEEE 802.16m mobile WiMAX\nYear: 2009\n\nAbstract: IEEE 802.16m standard is defining several improvements on IEEE 802.16e standard, one of them being handover (HO). This paper provides a policy to satisfy IEEE 802.16m benchmark of 150 msec or less for a hard handover (HO) between two base stations (BSs). To facilitate such fast HO, the target BSs are chosen before HO is sought. Such choice is made based on previously acquired knowledge of human mobility behavior. There are several initial ranging opportunities provided before the actual HO. Before the connection breaks with serving BS, target BS sets up its MAC states to allow instantaneous connection of service flows that are prevalent in the ongoing connection. Once the connection is broken, serving BS redirects the traffic to target BS while MSS, using the ranging parameters provided right before the connection breakup, initiates a connection request to the target BS. Several timers perform as check points so that critical operations are performed in timely manner.","Title: DREAM: Dynamic Resource and Task Allocation for Energy Minimization in Mobile Cloud Systems\nYear: 2015\n\nAbstract: To cope with increasing energy consumption in mobile devices, the mobile cloud offloading has received considerable attention from its ability to offload processing tasks of mobile devices to cloud servers, and previous studies have focused on single type tasks in fixed network environments. However, real network environments are spatio-temporally varying, and typical mobile devices have not only various types of tasks, e.g., network traffic, cloud offloadable/nonoffloadable workloads but also capabilities of CPU frequency scaling and network interface selection between WiFi and cellular. In this paper, we first jointly consider the following three dynamic problems in real mobile environments: 1) cloud offloading policy, i.e., determining to use local CPU resources or cloud resources; 2) allocation of tasks to transmit through networks and to process in local CPU; and 3) CPU clock speed and network interface controls. We propose a DREAM algorithm by invoking the Lyapunov optimization and mathematically prove that it minimizes CPU and network energy for given delay constraints. Trace-driven simulation based on real measurements demonstrates that DREAM can save over 35% of total energy than existing algorithms with the same delay. We also design DREAM architecture and demonstrate the applicability of DREAM in practice.","Title: Dual-side dynamic controls for cost minimization in mobile cloud computing systems\nYear: 2015\n\nAbstract: Mobile cloud computing (MCC) has been proposed to offload heavy computing jobs of mobile devices to cloud servers managed by cloud service provider (CSP), which enables the mobile devices to save energy and processing delay. Heretofore, cloud offloading policies in mobile devices and pricing/scheduling in CSP have been independently addressed. This paper is first to jointly account for both sides of mobile users and CSP in a unified mobile cloud computing framework. By invoking “Lyapunov drift-plus-penalty” technique, we propose dual-side control algorithms for the mobile users and CSP in two different scenarios: (i) In non-cooperation scenario, we propose a NC-UC algorithm for the mobile users and a NC-CC algorithm for the CSP to minimize each cost for given delay constraints. (ii) In cooperation scenario, we suggest a CP-JC algorithm for both cloud users and CSP to minimize the sum costs of them for given delay constraints. Trace-driven simulations demonstrate that NC-UC saves minimum 63% of cost by trading 8MB of average queue lengths when compared with the existing algorithms, and NC-CC achieves 71% of profit gain when compared with the same delay of existing scheme; moreover, the cooperation enables them to save additional costs and delays.","Title: TAES: Traffic-aware energy-saving base station sleeping and clustering in cooperative networks\nYear: 2015\n\nAbstract: We consider energy efficient base station sleeping and clustering problems in cooperative cellular networks where clusters of base stations jointly transmit to users. Our key idea of energy saving is to exploit a spatio-temporal fluctuation of traffic demand, which is to use minimal energy to provide capacity only slightly greater than varying traffic demand. Then, energy saving is possible without capacity loss. However, it is highly challenging to design traffic-aware algorithms without the future traffic demand information. To overcome this, we develop algorithms using queue instead of the future traffic information. For BS clustering problem, we propose an optimal algorithm that has polynomial complexity. For BS sleeping problem, which is a complex combinatorial problem, we propose two algorithms; One finds an optimal solution with reduced complexity compared to the exhaustive search, and the other finds a near-optimal solution with polynomial complexity. Through extensive simulations we show that the proposed algorithms can save significant energy when traffic load is low.","Title: Opportunistic shortest path forwarding in delay tolerant networks\nYear: 2010\n\nAbstract: Delay Tolerant Networks (DTNs) are characterized by probabilistic links formed among mobile nodes indicating their probabilistic encounters. Prior work on DTN routing uses expected delays as a routing metric to decide the next hop relay node for packet delivery to the destination. However, they measure the expected delays by taking the minimum of the expected delays over all possible paths from a candidate relay. This metric, denoted by MinEx, does not account for the opportunity gain enabled by having multiple paths to the destination through encountering multiple future neighbors. Since DTN routing uses as the relay the first encountered node satisfying given routing criteria, the random delays to multiple relay nodes should be aggregated. Thus, the true expected delays can be measured by taking the expectation of the minimum delays, denoted as ExMin, over all possible probabilistic paths from the candidate.","Title: Practicalizing Delay-Tolerant Mobile Apps with Cedos\nYear: 2015\n\nAbstract: Delay-tolerant Wi-Fi offloading is known to improve overall mobile network bandwidth at low delay and low cost. Yet, in reality, we rarely find mobile apps that fully support opportunistic Wi-Fi access. This is mainly because it is still challenging to develop delay-tolerant mobile apps due to the complexity of handling network disruptions and delays. In this work, we present Cedos, a practical delay-tolerant mobile network access architecture in which one can easily build a mobile app. Cedos consists of three components. First, it provides a familiar socket API whose semantics conforms to TCP while the underlying protocol, D2TP, transparently handles network disruptions and delays in mobility. Second, Cedos allows the developers to explicitly exploit delays in mobile apps. App developers can express maximum user-specified delays in content download or use the API for real-time buffer management at opportunistic Wi-Fi usage. Third, for backward compatibility to existing TCPbased servers, Cedos provides D2Prox, a protocol-translation Web proxy. D2Prox allows intermittent connections on the mobile device side, but correctly translates Web transactions with traditional TCP servers. We demonstrate the practicality of Cedos by porting mobile Firefox and VLC video streaming client to using the API. We also implement delay/disruption-tolerant podcast client and run a field study with 50 people for eight weeks. We find that up to 92.4% of the podcast traffic is offloaded to Wi-Fi, and one can watch a streaming video in a moving train while offloading 48% of the content to Wi-Fi without a single pause.","Title: Energy-Efficient Wi-Fi Sensing Policy Under Generalized Mobility Patterns With Aging.\nYear: 2016\n\nAbstract: An essential condition precedent to the success of mobile applications based on Wi-Fi e.g., iCloud is an energy-efficient Wi-Fi sensing. Clearly, a good Wi-Fi sensing policy should factor in both inter-access point AP arrival time IAT and contact duration time CDT distributions of each individual. However, prior work focuses on limited cases of those two distributions e.g., exponential or proposes heuristic approaches such as Additive Increase AI. In this paper, we first formulate a generalized functional optimization problem on Wi-Fi sensing under general inter-AP and contact duration distributions and investigate how each individual should sense Wi-Fi APs to strike a good balance between energy efficiency and performance, which is in turn intricately linked with users mobility patterns. We then derive a generic optimal condition that sheds insights into the aging property, underpinning energy-aware Wi-Fi sensing polices. In harnessing our analytical findings and the implications thereof, we develop a new sensing algorithm, called Wi-Fi Sensing with AGing WiSAG, and demonstrate that WiSAG outperforms the existing sensing algorithms up to 37% through extensive trace-driven simulations for which real mobility traces gathered from hundreds of smartphones is used.","Title: Just-In-Time Wlans: On-Demand Interference-Managed Wlan Infrastructures\nYear: 2016\n\nAbstract: In the past years, the centralized management of dense wireless local area networks has been emerged as a powerful paradigm for improving energy efficiency as well as avoiding severe interference. In this paper, we study the joint optimization on power-operation modes in access points (APs), channel selections and user-AP associations for improving energy efficiency and avoiding interference without sacrificing users' demands. To this end, we first formulate it as a mixed-integer programming using the popular Lyapunov approach, but it turns out to be computationally intractable, i.e., NP-hard. To address the issue, we propose a polynomial-time approximation algorithm and prove that it achieves a constant-factor approximation guarantee under mild assumptions. The main novelty underlying our algorithm design is based on a linear programming relaxation combining with two different greedy rounding schemes, where each achieves a constant-factor approximation in different regimes of parameters. We verify the performance of the proposed algorithm via extensive simulations and also demonstrate its practicability by implementing it at commercial APs using a Software-defined Networking framework, which shows that it reduces the wasted energy significantly while maintaining even higher throughput.","Title: Resource-Efficient Mobile Multimedia Streaming With Adaptive Network Selection.\nYear: 2016\n\nAbstract: From the advancements of mobile display and network infrastructure, mobile users can enjoy high quality mobile video streaming anywhere, anytime. However, most mobile users are still reluctant to use high quality video streaming when they are mobile due to costly cellular data and high energy consumption. In this work, we develop scheduling algorithms for resource-efficient mobile video streaming, which minimize the weighted sum objective of cellular cost and energy consumption. We first model the scheduling problem as a Markov decision process and propose an optimal scheduling algorithm based on dynamic programming. Then, we derive a heuristic algorithm that approximates the optimal algorithm. To evaluate the performance of proposed algorithms, we run simulation over YouTube video traces with audience retention graphs and mobility/connectivity traces in public transportation (e.g., commuting). Through extensive simulations, we show that our proposed scheduling algorithm has negligible performance loss compared to the optimal scheduling algorithm, where it saves 59% of cellular cost and 41% of energy compared to the YouTube default scheduler. We also implement our scheduling algorithm on an Android platform, and experimentally evaluate the performance compared to existing streaming policies.","Title: TravelMiner: On the Benefit of Path-Based Mobility Prediction\nYear: 2016\n\nAbstract: Mobility predictions are becoming more valuable in various applications with the rise of mobile devices. Given that existing prediction techniques are composed of two key procedures: 1) profiling past mobility trajectories as sequences of discrete atomic states (e.g., grid locations, semantic locations) and capturing them with an appropriate statistical model, 2) making a prediction on the next state using the statistical model, TravelMiner tackles the former with paths utilized as the atomic states for the first time, where the paths are defined as sub-trajectories with no branches. Comparing to available location-based predictors, TravelMiner makes a fundamental difference in that it is able to predict the sequence of paths rather than locations, which is far more detailed in the perspective of knowing the exact route to follow. TravelMiner enables this benefit by extracting disjoint paths from GPS trajectories via a similarity metric for curves, called Frechet distance and keeping the sequences of such paths in a statistical model, called probabilistic radix tree. Our extensive simulations over the GPS trajectories of 124 users reveal that TravelMiner outperforms other predictors in diverse popular performance metrics including predictability, prediction accuracy and prediction resolution.","Title: Dynamic Pricing, Scheduling, and Energy Management for Profit Maximization in PHEV Charging Stations.\nYear: 2017\n\nAbstract: Recently, as plug-in hybrid electric vehicles (PHEVs) take center stage for the eco-friendly and cost-effective transportation, commercial PHEV charging stations will be widely prevalent in the future. However, previous studies in the fields of the management of PHEV charging stations have not synthetically taken practical charging systems into account. In this paper, we study the profit-optimal m...","Title: CarrierMix: How Much Can User-side Carrier Mixing Help?\nYear: 2017\n\nAbstract: Energy consumption for cellular communication is increasingly gaining importance in smartphone battery lifetime as the bandwidth of wireless communication and the demand for mobile traffic increase. For energy-efficient cellular communication, we tackle two energy characteristics of cellular networks: (1) transmission energy highly varies upon channel condition, and (2) transmission of a packet accompanies unnecessary tail energy waste. Under the objective of transmitting packets when the best channel is provided as well as a number of packets are accumulated, we propose a new mobile collaboration framework “CarrierMix” that aggregates smart devices across multiple heterogeneous cellular carriers. Compared to the standalone operation, even without a buffering delay, CarrierMix allows better channel and reduces more tail energy in a statistical point of view. To maximize the energy benefit while maintaining the fairness among the nodes in collaboration, we further develop a dynamic programming framework providing the optimal algorithm of CarrierMix and its approximated heuristic. Trace-driven simulations on our experimental HSPA/EVDO/LTE network traces show that CarrierMix of five devices achieves up to 42 percent of energy reduction.","Title: Cedos: A Network Architecture and Programming Abstraction for Delay-Tolerant Mobile Apps.\nYear: 2017\n\nAbstract: Delay-tolerant Wi-Fi offloading is known to improve overall mobile network bandwidth at low delay and low cost. Yet, in reality, we rarely find mobile apps that fully support opportunistic Wi-Fi access. This is mainly because it is still challenging to develop delay-tolerant mobile apps due to the complexity of handling network disruptions and delays. In this paper, we present Cedos, a practical delay-tolerant mobile network access architecture in which one can easily build a mobile app. Cedos consists of three components. First, it provides a familiar socket API whose semantics conforms to TCP, while the underlying protocol, $\\\\text{D}^{2}$ TP, transparently handles network disruptions and delays in mobility. Second, Cedos allows the developers to explicitly exploit delays in mobile apps. App developers can express maximum user-specified delays in content download or use the API for real-time buffer management at opportunistic Wi-Fi usage. Third, for backward compatibility to existing TCP-based servers, Cedos provides $\\\\text{D}^{2}$ Prox, a protocol-translation Web proxy. $\\\\text{D}^{2}$ Prox allows intermittent connections on the mobile device side, but correctly translates Web transactions with traditional TCP servers. We demonstrate the practicality of Cedos by porting mobile Firefox and VLC video streaming client to using the API. We also implement delay/disruption-tolerant podcast client and run a field study with 50 people for eight weeks. We find that up to 92.4% of the podcast traffic is offloaded to Wi-Fi, and one can watch a streaming video in a moving train while offloading 48% of the content to Wi-Fi without a single pause.","Title: Hybrid Content Caching For Low End-To-End Latency In Cloud-Based Wireless Networks\nYear: 2017\n\nAbstract: In this paper, we consider the content caching design without requiring historical content access information or content popularity profiles in a hierarchical cellular network architecture. Our design aims to dynamically select caching locations for different contents where caching locations can be content servers, cloud units (CUs), and base stations (BSs). Our design objective is to support as high content request rates as possible while maintaining the finite service time. To tackle this design problem, we employ the Lyapunov optimization method where the caching algorithm is developed by minimizing the Lyapunov drift of a quadratic Lyapunov function of virtual queue backlogs. This solution approach requires to solve a max-weight problem, which is an NP-hard and difficult problem to solve due to the coupling between CU caching and BS caching decisions. By exploiting the submodularity of the objective function, we propose a hybrid caching algorithm which achieves the constant approximation ratio to the optimal performance. Trace-driven simulation results demonstrate that the proposed joint CU/BS caching algorithm achieves almost the same performance with the exhaustive search and outperforms the independent caching algorithm and heuristic joint caching algorithms in terms of average end-to-end latency and backhaul load reduction ratio.","Title: Traffic-Aware Energy-Saving Base Station Sleeping and Clustering in Cooperative Networks.\nYear: 2018\n\nAbstract: We consider energy efficient base station (BS) sleeping and clustering problems in cooperative cellular networks, where clusters of base stations jointly transmit to users. Our key idea of energy saving is to exploit spatio-temporal fluctuation of traffic demand, and use minimal energy to provide achievable data rate only slightly greater than varying traffic demand. However, it is highly challeng...","Title: Capacity, fairness, and queueing performance analysis of opportunistic scheduling with one-bit feedback.\nYear: 2018\n\nAbstract: In this paper, we consider opportunistic downlink scheduling in a cellular network that exploits multiuser diversity using one-bit feedback. To reduce the feedback overhead inherent in opportunistic scheduling, mobile stations are allowed to send one-bit information to the base station only when their channel quality exceeds a given threshold value. The objective of this paper is two-fold: (i) find the threshold value that can optimize queueing performance of the scheduler and (ii) investigate the relationship among capacity, fairness, and queueing performance. To this end, we first derive a formula for the sum-rate capacity as a function of the threshold. Next, we quantify the long-term and short-term fairness using Jain’s fairness index. Lastly, we develop a packet-level queueing model and derive QoS measures such as queueing delay and packet loss probability. Based on our analysis, we optimize the threshold value by considering both the traffic condition at the MAC layer and the temporal channel correlation at the PHY layer. Numerical results show that the optimized threshold can significantly reduce the average queueing delay and the packet loss probability. In addition, we find that there is a trade-off between short-term fairness and sum-rate capacity, whose control knob is the threshold. We show that, from a queueing performance perspective, supporting the sum-rate capacity (resp. the short-term fairness) is more important when the traffic is heavy (resp. light) or the wireless channel varies with low (resp. high) temporal correlation.","Title: Dual-Side Optimization for Cost-Delay Tradeoff in Mobile Edge Computing.\nYear: 2018\n\nAbstract: Mobile code offloading (MCO) is a technology that offloads computing tasks from mobile devices to remote servers managed by code offload service providers (CSPs). Nowadays, it is recommended that the remote servers be placed on the edge of the network to support modern applications, e.g., augmented reality, which demand stringent and ultralow latency or high bandwidth. To date, previous studies ha...","Title: Control of multi-resource infrastructures: Application to NFV and computation offloading\nYear: 2018\n\nAbstract: Network function virtualization (NFV) and Computation offloading (CO) are state-of-the-art technologies for flexible utilization of networking and processing resources. These two technologies are closely related in that they enable multiple physical entities to process a function provided in a service, and the service (or end host) chooses which resources to use. In this paper, we propose a generalized dual-resource system, which unifies NFV service and CO service frameworks, and formulate a multi-path problem for choosing resources to use in NFV and CO services. The problem is reformulated as a variational inequality by using Lagrange dual theory and saddle point theory. Based on this formulation, we propose an extragradient-based algorithm that controls and splits the sending rate of a service. We prove that the algorithm converges to an optimal point where system cost minus service utility is minimized. Simulations under diverse scenarios demonstrate that our algorithm achieves high quality of service while reducing the system cost by jointly considering dual-resource coupling and service characteristics.","Title: Hybrid Content Caching in 5G Wireless Networks: Cloud Versus Edge Caching.\nYear: 2018\n\nAbstract: Most existing content caching designs require accurate estimation of content popularity, which can be challenging in the dynamic mobile network environment. Moreover, emerging hierarchical network architecture enables us to enhance the content caching performance by opportunistically exploiting both cloud-centric and edge-centric caching. In this paper, we propose a hybrid content caching design t...","Title: Learning based Utility Maximization for Multi-Resource Management: Poster Abstract.\nYear: 2018\n\nAbstract: This poster addresses the problem of Network Utility Maximization (NUM) where multiple resources (computing/networking) participate in user services. NUM has usually been solved by Backpressure algorithms which has to build up queue size gradualy. This disadvantage stands out in the situation of multi-resource environment or multi-hop networking. To address the problem, we propose a reinforcement learning based algorithm that utilizes future prediction to overcome the previous limitation of non-learning based algorithms.","Title: Unknown Flow Detection with Imbalanced Traffic Data: Poster Abstract.\nYear: 2018\n\nAbstract: Unknown traffic is a serious problem in network traffic classification for network management and security, since it degrades the performance of a traffic classifier. We propose a machine learning-based classifier that can not only categorize the traffic of known classes but also detect unknown traffic in data imbalanced network environment, where frequency of traffic from one application outweighs that of other application. We improved the previous RTC model by adding data preprocessing module and simulated with synthesized dataset to show the effect of the data imbalance problem on classification accuracy and to validate the performance of our model in data-imbalanced network environment.","Title: Mobile Computation Offloading for Application Throughput Fairness and Energy Efficiency\nYear: 2019\n\nAbstract: Mobile computation offloading is emerging as a promising technology to enhance the computation power of mobile devices by borrowing processing resources from the cloud. However, using cloud resource is a double-edged sword because of the potentially enormous network energy consumption of mobile devices. In this paper, we study the mobile device resource management problem for application throughput fairness and energy efficiency in computation offloading environment. Our problem seeks to optimize task arrival rates, scheduling for local processing and offloading, CPU clock speed, and network interface selection, so as to maximize the energy-utility efficiency defined as achievable utility per unit energy consumption. The efficiency metric has a fractional form that is hard to deal with in general. To address this difficulty, we modify a general Lyapunov optimization technique and derive a series of short-term problems that change over time with respect to an unknown objective parameter. Then, we derive an offloading algorithm and prove that the algorithm maximizes the long-term energy-utility efficiency. Trace-driven simulations demonstrate that our algorithm achieves high-energy efficiency while maintaining throughput fairness among applications running on a mobile device.","Title: Virtual Beamforming and User Scheduling for Sub-Array Architecture in mmWave Networks.\nYear: 2019\n\nAbstract: In this letter, we propose a virtual beamforming and user scheduling technique, namely VirtualBus that attains higher beamforming gain by generating narrower beams in a sub-array mmWave network architecture. The proposed VirtualBus is beneficial as well in a sense that it does not increase the hardware complexity of the sub-array architecture. Through simulations on the practical scenario, we veri...","Title: TCP-friendly wireless multimedia flow control using ECN marking\nYear: 2002\n\nAbstract: In a wireless network, packet losses can be caused not only by network congestion but also by unreliable error-prone wireless links. Therefore, flow control schemes which use packet loss as a congestion measure cannot be directly applicable to a wireless network because congestion losses cannot be distinguished from wireless losses. We extend a so-called TCP-friendly flow control scheme, which was developed for the control of multimedia flows carried over UDP in the presence of TCP flows, to a wireless environment by using ECN (explicit congestion notification) marking capability with RED (random early detection) routers. By detecting congestion early, explicitly informing multimedia sources of congestion using ECN marking and calculating a TCP-friendly rate based on ECN-marked packet probability instead of packet loss probability, we are able effectively to separate the effect of wireless losses from flow control and thus prevent throughput degradation of multimedia flows traveling through wireless links. Also, we refine a well-known TCP throughput model developed for TCP-friendliness of multimedia flows such that the refined model provides more accurate estimate of TCP flows' throughput when both ECN marking and RED queue management are used. By simulation, we show that the proposed scheme does improve the quality of the delivered video significantly while maintaining TCP-friendliness for the case of wireless MPEG-4 video.","Title: Routing, path computation and traffic engineering in future Internet.\nYear: 2007\n\nAbstract: The current Internet architecture with integrated routing and forwarding planes has served the community well for the past three decades. The significant growth in Internet traffic and the need for support of very diverse sources has spurned research interest in new architectures. In particular, the next-generation Internet must cater to a variety of services with dynamically changing traffic demand and it is critical that it supports various quality of service (QoS) measures, to efficiently utilize network resources and to reduce operational costs.","Title: Multi-flow management for mobile data offloading\nYear: 2017\n\nAbstract: Cellular networks are facing explosive growth of mobile data traffic due to the proliferation of smart devices and traffic-intensive applications. As a cost-effective solution, delayed Wi-Fi offloading was introduced to shift the delay-tolerant traffic from cellular to Wi-Fi networks by trading additional delays. Our paper studies a multi-flow rate control problem where each flow has different traffic load and a deadline. To maximize user satisfaction defined as offloading efficiency minus disutility caused by deadline violation, we propose a dynamic programming-based rate control algorithm. Moreover, to reduce the computation and memory, we propose a simple threshold-based rate control algorithm.","Title: Simplified Stochastic Feedforward Neural Networks.\nYear: 2017\n\nAbstract: It has been believed that stochastic feedforward neural networks (SFNNs) have several advantages beyond deterministic deep neural networks (DNNs): they have more expressive power allowing multi-modal mappings and regularize better due to their stochastic nature. However, training large-scale SFNN is notoriously harder. In this paper, we aim at developing efficient training methods for SFNN, in particular using known architectures and pre-trained parameters of DNN. To this end, we propose a new intermediate stochastic model, called Simplified-SFNN, which can be built upon any baseline DNNand approximates certain SFNN by simplifying its upper latent units above stochastic ones. The main novelty of our approach is in establishing the connection between three models, i.e., DNN-u003eSimplified-SFNN-u003eSFNN, which naturally leads to an efficient training procedure of the stochastic models utilizing pre-trained parameters of DNN. Using several popular DNNs, we show how they can be effectively transferred to the corresponding stochastic models for both multi-modal and classification tasks on MNIST, TFD, CASIA, CIFAR-10, CIFAR-100 and SVHN datasets. In particular, we train a stochastic model of 28 layers and 36 million parameters, where training such a large-scale stochastic network is significantly challenging without using Simplified-SFNN","Title: Practical dynamic interference management in multi-carrier multi-cell wireless networks: A reference user based approach\nYear: 2010\n\nAbstract: In order to overcome low performance of conventional static interference management algorithms and high complexity of existing dynamic interference management algorithms, this paper proposes an efficient, low-complex and fully distributed power control and user scheduling algorithm in downlink multi-carrier multi-cell wireless networks. We decompose the original optimization problem, which requires intractable computation complexity for global optimality, into per-BS (base station) problems based on the notion of reference user. This idea is a good approximation of the optimal algorithms that permits significant complexity reduction, yet sustains near-optimal performance. We further reduce feedback overhead to make the resulting algorithm more practical by exploiting temporal correlations and spatial simplification. We verify the efficiency of our proposed algorithm through extensive simulations over various topologies and scenarios motivated by the current 3G BS deployment map.","Title: Proximity-Aware Location Based Collaborative Sensing for Energy-Efficient Mobile Devices\nYear: 2019\n\nAbstract: A fundamental question in the study of location-based mobile sensing is how much energy can be saved while still guaranteeing the reliable localization accuracy. In this paper, we analyze key features of human proximity and find a motivation which implies that the energy-efficient and accurate localization is possible by sharing the locations of nearby mobile devices. From the location-based collaborative sensing idea, we formulate an optimization problem which aims to minimize the total number of location measurements for a given fairness criterion. Then, we propose a practical and distributed location sharing (DLS) protocol and an optimal parameter control algorithm (OWD) which makes the DLS protocol attain an asymptotic optimal performance. Via extensive simulations under various environments including real mobility traces, we verify that the proposed DLS+OWD policy significantly reduces the average power consumption of mobile devices with a higher fairness compared to the existing algorithms.","Title: Hardware-adaptive Efficient Latency Prediction for NAS via Meta-Learning.\nYear: 2021\n\nAbstract: For deployment, neural architecture search should be hardware-aware, in order to satisfy the device-specific constraints (e.g., memory usage, latency and energy consumption) and enhance the model efficiency. Existing methods on hardware-aware NAS collect a large number of samples (e.g., accuracy and latency) from a target device, either builds a lookup table or a latency estimator. However, such approach is impractical in real-world scenarios as there exist numerous devices with different hardware specifications, and collecting samples from such a large number of devices will require prohibitive computational and monetary cost. To overcome such limitations, we propose Hardware-adaptive Efficient Latency Predictor (HELP), which formulates the device-specific latency estimation problem as a meta-learning problem, such that we can estimate the latency of a model's performance for a given task on an unseen device with a few samples. To this end, we introduce novel hardware embeddings to embed any devices considering them as black-box functions that output latencies, and meta-learn the hardware-adaptive latency predictor in a device-dependent manner, using the hardware embeddings. We validate the proposed HELP for its latency estimation performance on unseen platforms, on which it achieves high estimation performance with as few as 10 measurement samples, outperforming all relevant baselines. We also validate end-to-end NAS frameworks using HELP against ones without it, and show that it largely reduces the total time cost of the base NAS method, in latency-constrained settings.","Title: zTT: learning-based DVFS with zero thermal throttling for mobile devices\nYear: 2021\n\nAbstract: ABSTRACTDVFS (dynamic voltage and frequency scaling) is a system-level technique that adjusts voltage and frequency levels of CPU/GPU at runtime to balance energy efficiency and high performance. DVFS has been studied for many years, but it is considered still challenging to realize a DVFS that performs ideally for mobile devices for two main reasons: i) an optimal power budget distribution between CPU and GPU in a power-constrained platform can only be defined by the application performance, but conventional DVFS implementations are mostly application-agnostic; ii) mobile platforms experience dynamic thermal environments for many reasons such as mobility and holding methods, but conventional implementations are not adaptive enough to such environmental changes. In this work, we propose a deep reinforcement learning-based frequency scaling technique, zTT. zTT learns thermal environmental characteristics and jointly scales CPU and GPU frequencies to maximize the application performance in an energy-efficient manner while achieving zero thermal throttling. Our evaluations for zTT implemented on Google Pixel 3a and NVIDIA JETSON TX2 platform with various applications show that zTT can adapt quickly to changing thermal environments, consistently resulting in high application performance with energy efficiency. In a high-temperature environment where a rendering application with the default mobile DVFS fails to keep producing more than a target frame rate, zTT successfully manages to do so even with 23.9% less average power consumption.","Title: Energy and Delay Guaranteed Joint Beam and User Scheduling Policy in 5G CoMP Networks\nYear: 2022\n\nAbstract: Massive Multi-Input Multi-Output (MIMO) and Coordinated MultiPoint (CoMP) technologies in Cloud-RAN (C-RAN) architecture become inevitable trend due to the advent of next-generation mobile applications, which are traffic-intensive, such as ultra high definition (UHD) video. In this paper, we study a joint beam activation and user scheduling problem in a 5G cellular network with massive MIMO and Co...","Title: R-FEC: RL-based FEC Adjustment for Better QoE in WebRTC\nYear: 2022\n\nAbstract: ABSTRACTThe demand for video conferencing applications has seen explosive growth while users still often face unsatisfactory quality of experience (QoE). Video conferencing applications adopt Forward Error Correction (FEC) as a recovery mechanism to meet tight latency requirements and overcome packet losses prevalent in the network. However, many studies mainly focused on video rate control by neglecting the complex interactions of this video recovery mechanism on the rate control and its impact on the user QoE. Deciding the right amount of FEC for the current video rate under a dynamically changing network environment is not straightforward. For instance, the higher FEC may enhance the tolerance to packet losses, but it may increase latency due to FEC processing overhead and hurt the video quality due to the additional bandwidth used for FEC. To address this issue, we propose R-FEC which is a reinforcement learning (RL) based framework for video and FEC bitrate decisions in video conferencing. R-FEC aims to improve overall QoE by automatically learning through the results of past decisions and adjusting video and FEC bitrates to maximize the user QoE while minimizing the congestion in the network. Our experiments show that R-FEC outperforms the state-of-the-art solutions in video conferencing, with up to 27% improvement in its video rate and 6dB PSNR improvement in video quality over the default WebRTC."],"string":"[\n \"Title: ExMin: A routing metric for novel opportunity gain in Delay Tolerant Networks\\nYear: 2014\\n\\nAbstract: Delay Tolerant Networks (DTNs) are characterized by intermittently connected links formed by mobile nodes' probabilistic encounters. Most DTN routing techniques use the first encountered node who has smaller routing metric as a relay node. Prior work on DTN routing can be broadly classified into one which takes the minimum out of expected delays for all possible individual routing paths, referred to as MinEx, as a routing metric to decide the next hop relay node. Fundamentally, MinEx has no difference from the shortest path computation in conventional multi-hop networks, where a link weight is the expected inter-meeting time. However in DTNs, nodes meet intermittently by their mobility, hence the links formed from the meetings are probabilistic. In this environment, MinEx often fails to accurately estimate the actual delay since opportunism in nodes' intermittent meeting is not properly taken into account. In this paper, to exploit the true opportunism, we first propose a metric called ExMin which stochastically calculates the metric by taking the expectation of the minimum delays over all possible routes. We further show that ExMin can be computed online by relying only on local information sharing. Our extensive experiments involving three realistic network scenarios created by two vehicle traces (about 1500 Shanghai taxies and 500 San Francisco taxies) and one human mobility trace (93 KAIST students) show that ExMin outperforms MinEx by up to 30% under either of DTN environments allowing single-copy or multi-copies of a packet.\",\n \"Title: Multi-Path Aggregate Flow Control for Real-Time Traffic Engineering\\nYear: 2008\\n\\nAbstract: We present an online distributed traffic engineering method for ISP networks with multi-path routing. The method is based on edge-to-edge aggregate flow control that balances load and makes the network congestion-free in real time, responding to actual traffic demands whether they are underload or overloaded. Moreover, it allows ISPs to apply various bandwidth-sharing policies to edge-to-edge flows, as desired. Our simulations confirm that the proposed method works as designed for TCP sources that have their own end-to-end congestion control mechanism and enhance the performance and the efficiency of the the network.\",\n \"Title: Downlink resource allocation in multi-carrier systems: frequency-selective vs. equal power allocation\\nYear: 2008\\n\\nAbstract: This paper revisits equal power allocation from the viewpoint of asymptotic network utility maximization (NUM) problem in multi-carrier systems. It is a well-known fact that the equal power allocation is near optimal to the sum capacity maximization problem in high SNR (signal-to-noise ratio) regime, i.e., optimal water-filling approximates to equal power allocation in that case. Due to this property together with its simplicity, the equal power allocation has been adopted in several researches, but its performance in other problems has not been clearly understood. We evaluate the suitability of equal power allocation in NUM problem which turns into various resource sharing policies according to utility functions. Namely, our conclusion is that in frequency selective channels, the equal power allocation is near optimal for efficiency-oriented resource sharing policy, but when fairness is emphasized, its performance is severely degraded and thus frequency-selective power allocation is necessary. For this, we develop a suboptimal subcarrier and frequency-selective power allocation algorithm for asymptotic NUM problem using the gradient-based scheduling theory and compare the performance of equal power allocation and the developed algorithm. Extensive simulation results are presented to verify our arguments.\",\n \"Title: Utility-Optimal Multi-Pattern Reuse in Multi-Cell Networks\\nYear: 2011\\n\\nAbstract: Achieving sufficient spatial capacity gain through the use of small cells requires careful consideration of inter-cell interference (ICI) management via BS power coordination coupled with user scheduling inside cells. Optimal algorithms are known to be difficult to implement due to high computation and signaling overhead. This study proposes joint pattern-based ICI management and user scheduling algorithms that are practically implementable. The key idea is to decompose the original problem into two sub-problems in which ICI management is run at a slower time scale than user scheduling. We empirically show that even with such a slow tracking of system dynamics at the ICI management part, the decomposed approach achieves a considerable performance increase compared to conventional universal reuse schemes.\",\n \"Title: Rate control algorithms for the ATM ABR service\\nYear: 1997\\n\\nAbstract: Over the last couple of years both the ATM Forum and ITU-T have converged on a closed-loop, feedback based, rate control mechanism as the framework for the Available Bit Rate ATM Transfer Capability. In this framework, an ABR source adapts its transmission rate to changing characteristics of the ATM network by either testing periodically the state of the network or through direct feedback from the network. The state of the network is conveyed to the source either as it simple binary feedback signaling congestion or no congestion, or as an explicit rate indicating the rate at which the source can transmit. In this paper we review the detailed framework for the ABR service standardized by the ATM Forum, the underlying service philosophy and protocol design goals for ABR flow control, and the premises and high-level performance characteristics for the more promising ABR rate control schemes proposed so far.\",\n \"Title: Performance Enhancement In Obs Network With Flow Control And Edge Delay Method\\nYear: 2006\\n\\nAbstract: This paper examines burst contention resolution problems in optical burst switching (OBS) networks. Since burst contentions take place i) when the network is congested by increased input traffic, or ii) two or more bursts demand the same wavelength exactly at the same time even though there is no congestion. From these insights, we present two novel methods that make higher throughputs and lower burst losses in the OBS network.First, from the viewpoint of flow control, we propose a burst flow control algorithm that controls the length of a burst based on the congestion price on its path. With the proposed flow control algorithm, the OBS network achieves improved efficiency and fairness compared to the case where a burst contention resolution scheme is solely used.Next, we develop an edge delay method which decreases burst losses especially when two or more bursts are overlapped in the core nodes. When some bursts need buffering to avoid contentions at core nodes, the proposed method makes them be delayed for the required buffering time at its ingress edge instead. Through extensive simulations, we demonstrate its performance.\",\n \"Title: Joint network-wide opportunistic scheduling and power control in multi-cell networks\\nYear: 2009\\n\\nAbstract: We present a unified analytical framework that maximizes generalized utilities of a wireless network by network-wide opportunistic scheduling and power control. That is, base stations in the network jointly decide mobile stations to be served at the same time as the transmission powers of base stations are coordinated to mitigate the mutually interfering effect. Although the maximization at the first glance appears to be a mixed, twofold and nonlinear optimization requiring excessive computational complexity, we show that the maximization can be transformed into a pure binary optimization with much lower complexity. To be exact, it is proven that binary power control of base stations is necessary and sufficient for maximizing the network-wide utilities under a physical layer regime where the channel capacity is linear in the signal-to-interference-noise ratio. To further reduce the complexity of the problem, a distributed heuristic algorithm is proposed that performs much better than existing opportunistic algorithms. Through extensive simulations, it becomes clear that network-wide opportunistic scheduling and power control is most suitable for fairness-oriented networks and under loaded networks. We believe that our work will serve as a cornerstone for network-wide scheduling approaches from theoretical and practical standpoints.\",\n \"Title: Making 802.11 DCF Optimal: Design, Implementation, and Evaluation\\nYear: 2012\\n\\nAbstract: This paper proposes a new protocol called Optimal DCF (O-DCF). Inspired by a sequence of analytic results, O-DCF modifies the rule of adapting CSMA parameters, such as backoff time and transmission length, based on a function of the demand-supply differential of link capacity captured by the local queue length. Unlike clean-slate design, O-DCF is fully compatible with 802.11 hardware, so that it can be easily implemented only with a simple device driver update. Through extensive simulations and real experiments with a 16-node wireless network testbed, we evaluate the performance of O-DCF and show that it achieves near-optimality, and outperforms other competitive ones, such as 802.11 DCF, optimal CSMA, and DiffQ in a wide range of scenarios.\",\n \"Title: A simple, scalable, and stable explicit rate allocation algorithm for max-min flow control with minimum rate guarantee\\nYear: 2001\\n\\nAbstract: We present a novel control-theoretic explicit rate (ER) allocation algorithm for the max-min flow control of elastic traffic services with minimum rate guarantee in the setting of the ATM available bit rate (ABR) service. The proposed ER algorithm is simple in that the number of operations required to compute it at a switch is minimized, scalable in that per-virtual-circuit (VC) operations including per-VC queueing, per-VC accounting, and per-VC state management are virtually removed, and stable in that by employing it, the user transmission rates and the network queues are asymptotically stabilized at a unique equilibrium point at which max-min fairness with minimum rate guarantee and target queue lengths are achieved, respectively. To improve the speed of convergence, we normalize the controller gains of the algorithm by the estimate of the number of locally bottlenecked VCs. The estimation scheme is also computationally simple and scalable since it does not require per-VC accounting either. We analyze the theoretical performance of the proposed algorithm and verify its agreement with the practical performance through simulations in the case of multiple bottleneck nodes. We believe that the proposed algorithm will serve as an encouraging solution to the max-min flow control of elastic traffic services, the deployment of which has been debated long due to their lack of theoretical foundation and implementation complexity\",\n \"Title: Adaptive multi-pattern reuse in multi-cell networks\\nYear: 2009\\n\\nAbstract: Multiuser information-theoretic analysis of achievable communication rate regions over networks traditionally assumes that individual sources of information are independent. However, fully exploiting network-wide synergies requires an understanding of ...\",\n \"Title: Towards optimal MAC without message passing in wireless networks\\nYear: 2009\\n\\nAbstract: One of the key messages in significant research on cross-layer design of wireless networks over the past 15 years is that extensive message passing may be necessary to achieve optimal performance. Heavy message passing is obviously an undesirable feature for practical implementation due to its reduced actual throughput and security issues. In this paper, we first summarize our preliminary work that does not need message passing, yet achieves near-optimality. Then, we present our recent efforts to realize such an algorithmic solution in a real network, e.g., IEEE 802.11-based systems, and discuss possible future research directions.\",\n \"Title: SLAW: A New Mobility Model for Human Walks\\nYear: 2009\\n\\nAbstract: Simulating human mobility is important in mobile networks because many mobile devices are either attached to or controlled by humans and it is very hard to deploy real mobile networks whose size is controllably scalable for performance evaluation. Lately various measurement studies of human walk traces have discovered several significant statistical patterns of human mobility. Namely these include truncated power-law distributions of flights, pause-times and inter-contact times, fractal way-points, and heterogeneously defined areas of individual mobility. Unfortunately, none of existing mobility models effectively captures all of these features. This paper presents a new mobility model called SLAW (self-similar least action walk) that can produce synthetic walk traces containing all these features. This is by far the first such model. Our performance study using using SLAW generated traces indicates that SLAW is effective in representing social contexts present among people sharing common interests or those in a single community such as university campus, companies and theme parks. The social contexts are typically common gathering places where most people visit during their daily lives such as student unions, dormitory, street malls and restaurants. SLAW expresses the mobility patterns involving these contexts by fractal way points and heavy-tail flights on top of the way points. We verify through simulation that SLAW brings out the unique performance features of various mobile network routing protocols.\",\n \"Title: A distributed utility max-min flow control algorithm\\nYear: 2006\\n\\nAbstract: A fair allocation of utility (application-layer performance) is essential in providing QoS (Quality of Service) guarantee. However, there have been few researches in the literature of utility-fair network resource allocation scheme. In this paper, we propose a distributed utility max–min flow control algorithm which accommodates application diversity in that it does not require the concavity of utility functions, and is scalable in that it does not require any per-flow operation in the network. The algorithm is proved to be convergent under the assumption that there exists a single bottleneck link and the communication delay between any two links in the network is bounded. Although the convergence of the algorithm is analyzed only for the case of a single bottleneck link, we show through simulations that the proposed algorithm works as designed for the case of multiple bottleneck links as well.\",\n \"Title: Performance evaluation of a DTN as a city-wide infrastructure network\\nYear: 2009\\n\\nAbstract: As providing data networks in an urban district through a cellular system is expensive and does not provide sufficient capacity, use of a wireless mesh network is generally considered as a way to achieve more capacity. While a mesh network has sizable installation costs to deploy routers and still does not provide abundant capacity, it is worthwhile to consider a DTN whose capacity is abundant without additional installation costs to support a mesh network. In this paper, we propose an architecture of a DTN as an infrastructure network and study the capacity region of the DTN over the real mobility of Shanghai taxies. We identify and verify several key characteristics of the DTN capacity, including time-varying and asymmetric characteristics. Our simulation results show that the capacity of the DTN is superior to a mesh network most of the time for both single-link and multi-link scenarios.\",\n \"Title: Combined QoS Scheduling and Call Admission Control Algorithm in Cellular Networks\\nYear: 2006\\n\\nAbstract: In this paper, a scheduling problem in wireless networks is considered when there simultaneously exist CBR (constant bit rate) users requiring exact minimum average throughput guarantee and EMG (elastic with minimum guarantee) users requiring minimum average throughput guarantee and more if possible. By exploiting utility maximization problem without minimum throughput constraint and newly defined utility functions, we propose a combined scheduling and call admission control scheme that exactly guarantees the minimum requirements of CBR and EMG users and then allocates the leftover capacity to EMG users. In the proposed scheme, it is easy to give priority to particular users so that they are guaranteed their requirements prior to any other user. Moreover, the priority structure enables the proposed measurement-based call admission control algorithm to perform admission trial without affecting the minimum performance of existing users. We show through mathematical analysis and simulations that our scheme works as designed.\",\n \"Title: Dynamic bandwidth allocation for efficient transport of real-time VBR video over ATM\\nYear: 1994\\n\\nAbstract: The paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. The authors describe video traffic in the frequency domain: the low frequency signal captures the slow time-variation of consecutive scene changes; the high frequency signal exhibits the feature of strong frame autocorrelation. The study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low, frequency signal. Since the time scale of scene changes is usually in the range of a second or longer, the low frequency video signal is defined in a well-founded low frequency band. Hence, it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: the recursive least square method vs. the time delay neural network method. A time delay neural network with low-complexity high-order architecture, called a “pi-sigma network”, is successfully used to predict scene changes. The proposed dynamic bandwidth allocation scheme is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic with guaranteed quality of services\",\n \"Title: Utility Max-Min Flow Control Using Slope-Restricted Utility Functions\\nYear: 2005\\n\\nAbstract: We present a network architecture for the distributed utility max-min flow control of elastic and nonelastic flows where utility values of users (rather than data rates of users) are enforced to achieve max-min fairness. The proposed link algorithm converges to utility max-min fair bandwidth allocation in the presence of round-trip delays without using the information of users' utility functions. To show that the proposed algorithm can be stabilized not locally but globally, we found that the use of nonlinear control theory is inevitable. Even though we use a distributed flow-control algorithm, it is shown that any kind of utility function can be used as long as the minimum slopes of the functions are greater than a certain positive value. Though our analysis is limited to the single-bottleneck and homogeneous-delay case, we believe that the proposed algorithm is the first to achieve utility max-min fairness with guaranteed stability in a distributed manner\",\n \"Title: Research challenges towards the Future Internet\\nYear: 2011\\n\\nAbstract: The convergence of computer-communication networks towards an all-IP integrated network has transformed Internet in a commercial commodity that has stimulated an un-precedent offer of novel communication services that are pushing the Internet architecture and protocols well beyond their original design. This calls for extraordinary research efforts at all levels of the protocol stack to address the challenges of existing and future networked applications and services in terms of scalability, mobility, flexibility, security, etc. In this article we focus on some hot research areas and discuss the research issues that need to be tackled for addressing the multiple challenges of the Future Internet. Far from being a comprehensive analysis of all the challenges faced by the Future Internet, this article tries to call the attention of Computer Communications readers to new and promising research areas, identified by members of the journal editorial board to stimulate further research activities in these areas. The survey of these research areas is then complemented with a brief review of the on-going activities in the other important research areas towards the Future Internet.\",\n \"Title: Combined packet scheduling and call admission control with minimum throughput guarantee in wireless networks\\nYear: 2007\\n\\nAbstract: In this paper, a scheduling problem is considered in the cellular network where there exist CBR (constant bit rate) users requiring exact minimum average throughput guarantee, and EMG (elastic with minimum guarantee) users requiring minimum average throughput guarantee and more if possible. We propose a combined scheduling and call admission control algorithm that exactly guarantees the minimum requirements of CBR and EMG users, and then allocates the leftover capacity to EMG users. The proposed algorithm is developed using utility maximization problem without minimum throughput constraints and newly defined utility functions. In the algorithm, it is easy to give priority to particular users so that their requirements are guaranteed prior to any other user. Moreover, the priority structure enables the proposed measurement-based call admission control algorithm to perform admission trial without affecting the minimum required throughput of ongoing users. We verify the performance of our algorithm through mathematical analysis and simulations.\",\n \"Title: Spatial Resource Reuse in the Multi-Hop Cellular Networks: Difficulties and Benefits\\nYear: 2008\\n\\nAbstract: The introduction of relays into legacy cellular networks is gaining more of an interest in the 4th generation (4G) wireless systems. In the presence of relays, simultaneous transmission of both base stations (BS) and relay stations (RS) on the same resources is possible, and consequently much higher throughput can be achieved. However, determining the set of links which will be turned on at the same time is usually considered a NP-complete combinatorial problem. Moreover, it requires cooperation between BSs and RSs of independent cells. In such context, we briefly address the difficulties of spatial resource reuse from the graph-theoretical perspective. Next, our focus shifts to developing a simple but efficient radio resource management algorithm which enables the spatial resource reuse, the pricing-based radio resource management (PRRM) strategy. The PRRM performs spatial reuse for interference-free users operating in the high signal-to-interference-and-noise ratio (SINR) region, while guaranteeing the signal quality of interference-susceptible users usually located near the coverage boundary. By applying the PRRM, we evaluate the potential benefits of the spatial resource reuse.\",\n \"Title: (Sigma,Rho)-Characterization Based Connection Control For Guaranteed Services In High Speed Networks\\nYear: 1995\\n\\nAbstract: In this paper we present a method to establish real-time connections with guaranteed qualityof-services, based on per-session (oe; ae)-characterization. Under two distinctive service disciplines,rate proportional processor sharing and fixed rate processor sharing, we derive tighter probabilisticbounds on per-session end-to-end average cell loss rate, which is caused by either buffer overflowin the route or excessive delay at the destination. One remarkable feature of the boundingsolutions ...\",\n \"Title: Greening Effect of Spatio-Temporal Power Sharing Policies in Cellular Networks with Energy Constraints.\\nYear: 2012\\n\\nAbstract: Greening effect in interference management (IM), a way of enhancing spectrum sharing via intelligent transmit power control, can be achieved by the fact that as BSs moderately reduce their transmit powers, the performance degradation decreases slower than linearly, yet a considerable overall energy saving is expected due to transmit powers' exerting influence on operational power. This paper inves...\",\n \"Title: Flow control with processing constraint\\nYear: 2005\\n\\nAbstract: In this letter we re-examine flow control issues for a network environment where transmission links and CPUs on a data path can be jointly bottlenecked. We show that flow control without consideration of CPU congestion can significantly lose both fairness and efficiency in this environment. As a solution to this problem, we establish the notion of dual-resource propor- tional fairness, propose a distributed algorithm to achieve this objective and demonstrate its performance through simulations.\",\n \"Title: Detection of DDoS traffic by using the technical analysis used in the stock market\\nYear: 2009\\n\\nAbstract: We propose a method for detecting Distributed Denial of Service (DDoS) traffic in real-time inside the network. For this purpose, we borrow the concepts of Moving Average Convergence Divergence, Rate of Change, and Relative Strength Index, which are used for technical analysis in the stock market. Due to the fact that the method is based on a quantitative, rather than a heuristic, detection level, DDoS traffic can be detected with greater accuracy (by reducing the false alarm ratio). Through detection algorithm and simulation results, we show how the detection level is determined and demonstrate the degree to which the accuracy of detection is enhanced.\",\n \"Title: QoS Scheduling for Heterogeneous Traffic in OFDMA-Based Wireless Systems\\nYear: 2009\\n\\nAbstract: In this paper, we propose a scheduling framework for heterogeneous traffic in OFDMA-based wireless systems. The proposed scheduling algorithm not only satisfies the QoS requirements of the real-time traffic but also maximizes the utility of the non real-time traffic. Step-by-step approach is used to achieve these two objectives simultaneously with low complexity and traffic class prioritization. A well-known bipartite matching algorithm and a standard gradient scheduling algorithm are adopted for the QoS scheduling of the real-time traffic and for the utility maximization scheduling of the non real-time traffic, respectively. Moreover, a noble beta deadline parameter is introduced to control the balance between the QoS provisioning and the diversity gain. Extensive simulation results in various scenarios are provided to demonstrate the good features of our scheduling framework.\",\n \"Title: Max-Contribution: On Optimal Resource Allocation in Delay Tolerant Networks\\nYear: 2010\\n\\nAbstract: This is by far the first paper considering joint optimization of link scheduling, routing and replication for disruption-tolerant networks (DTNs). The optimization problems for resource allocation in DTNs are typically solved using dynamic programming which requires knowledge of future events such as meeting schedules and durations. This paper defines a new notion of optimality for DTNs, called snapshot optimality where nodes are not clairvoyant, i.e., cannot look ahead into future events, and thus decisions are made using only contemporarily available knowledge. Unfortunately, the optimal solution for snapshot optimality still requires solving an NP-hard problem of maximum weight independent set and a global knowledge of who currently owns a copy and what their delivery probabilities are. This paper presents a new efficient approximation algorithm, called Distributed Max-Contribution (DMC) that performs greedy scheduling, routing and replication based only on locally and contemporarily available information. Through a simulation study based on real GPS traces tracking over 4000 taxies for about 30 days in a large city, DMC outperforms existing heuristically engineered resource allocation algorithms for DTNs.\",\n \"Title: Stabilized Edge-to-Edge Aggregate Flow Control\\nYear: 2004\\n\\nAbstract: In this paper, we present a distributed flow control scheme which achieves weighted max-min fair bandwidth allocation among all source-destination pairs on a per-aggregate basis within its network. The motivation behind the scheme is the absence of per-aggregate flow control in the current Internet, resulting in inability to enforce a certain fairness on source-destination flows. In our scheme, the distributed algorithm to compute weighted max-min fair rates is based on PI control in feedback control theory. We mathematically prove the asymptotic stability of the algorithm in presence of aggregate flows with heterogeneous round-trip delays. Through simulations we demonstrate the effectiveness of the proposed scheme in controlling per-aggregate flows.\",\n \"Title: Fundamental limits of input rate control in high speed network\\nYear: 1993\\n\\nAbstract: The fundamental limits of input rate control by specific analysis in the frequency domain are explored. Both deterministic and stochastic analyses are developed. The simple deterministic analysis helps provide knowledge about the performance tradeoff for input rate control in a high-speed network\",\n \"Title: Power allocation policies with full and partial inter-system channel state information for cognitive radio networks\\nYear: 2013\\n\\nAbstract: This paper investigates several power allocation policies in orthogonal frequency division multiplexing -based cognitive radio networks under the different availability of inter-system channel state information (CSI) and the different capability of licensed primary users (PUs). Specifically, we deal with two types of PUs having different capabilities: a dumb (peak interference-power tolerable) PU and a more sophisticated (average interference-power tolerable) PU. For such PU models, we first formulate two optimization problems that maximize the capacity of unlicensed secondary user (SU) while maintaining the quality of service of PU under the assumption that both intra- and inter-system CSI are fully available. However, due to loose cooperation between SU and PU, it may be difficult or even infeasible for SU to obtain the full inter-system CSI. Thus, under the partial inter-system CSI setting, we also formulate another two optimization problems by introducing interference-power outage constraints. We propose optimal and efficient suboptimal power allocation policies for these four problems. Extensive numerical results demonstrate that the spectral efficiency achieved by SU with partial inter-system CSI is less than half of what is achieved with full inter-system CSI within a reasonable range of outage probability (e.g., less than 10 %). Further, it is shown that the average interference-power tolerable PU can help to increase the saturated spectral efficiency of SU by about 20 and 50 % in both cases of full and partial inter-system CSI, respectively.\",\n \"Title: Experimental evaluation of optimal CSMA\\nYear: 2011\\n\\nAbstract: By `optimal CSMA' we denote a promising approach to maximize throughput-based utility in wireless networks without message passing or synchronization among nodes. Despite the theoretical guarantees on the performance of these protocols, their evaluation in real networking scenarios has been preliminary. In this paper, we propose a methodical approach for the first comprehensive evaluation of optimal CSMA, via experimentation with a custom implementation. Example findings include; 1) hidden terminals with symmetric channels can drive the protocol to a state of extreme contention aggressiveness due to the low service received by flows. Since increasing aggressiveness does not mitigate collisions but actually aggravates them, optimal CSMA enters a positive-feedback loop eventually reaching a deadlock state of total flow starvation; 2) however, the use of RTS/CTS in such scenarios can reduce collisions to lower levels, restoring throughput and preventing an excessive contention aggressiveness by optimal CSMA flows; 3) in practical hidden terminal scenarios with physical layer capture optimal CSMA reduces the aggressiveness of dominant flows, but the contention window sizes used by such adaptation mechanism are not long enough to solve competing flows' starvation when carrier sensing fails; 4) topologies with a “flow-in-the-middle” yield starvation in traditional CSMA but fairness in optimal CSMA, because its contention aggressiveness adaptation creates frequent transmission opportunities for the central (otherwise starved) flow; 5) optimal CSMA excessively prioritizes links with low channel quality, due to queue-based control that does not otherwise incorporate channel conditions; 6) in its current design, optimal CSMA conflicts with window-based end-to-end congestion control, and leads to a efficiency-fairness tradeoff in TCP performance. This study deepens our understanding of optimal CSMA and the general adaptation philosophy behind its design, and - - the derived insights suggest enhancements to optimal CSMA theory.\",\n \"Title: Opportunistic Relaying in Cellular Network for Capacity and Fairness Improvement\\nYear: 2007\\n\\nAbstract: In this paper, we study how the cooperative relaying can improve both capacity and fairness in cellular network. The capacity and fairness have a trade-off relationship, so increasing cell throughput deteriorates fairness and vice versa. First, we show that the achievable average throughput region can be enlarged by using the cooperative relaying. This enlarged region means that capacity and fairness can be improved at the same time with an adequate scheduling algorithm. Thus, secondly we propose a generalized scheduling algorithm for cooperative relaying. The proposed scheduling algorithm can improve both capacity and fairness at the expense of cooperation among users. From simulations, we show that the trade-off relationship can be surpassed and the unfairness problem in the heterogeneous channel condition can be solved by the opportunistic relaying.\",\n \"Title: A TCP starvation problem in combining TCP and max-weight scheduling of cross-layer algorithms in WMNs\\nYear: 2009\\n\\nAbstract: In this paper, we investigate the problem coming from the adaptation of legacy protocol TCP to the cross-layer protocols that is likely happen in future Internet. We point out named a TCP starvation problem in combining TCP and max-weight scheduling of cross-layer algorithms in wireless mesh networks. TCP starvation occurs when neighbor nodes are already scheduled with large queue length. To overcome TCP starvation as denoted in this paper, we propose a simple remedy named fake-ACK algorithm.\",\n \"Title: Two-Hop Opportunistic Scheduling in Cooperative Cellular Networks\\nYear: 2012\\n\\nAbstract: Due to the tradeoff between capacity and fairness in a wide variety of networks, increasing one objective may deteriorate the other. This paper investigates the possibility of improving capacity and fairness at the same time, specifically in two-hop cellular networks. First, we prove that an achievable capacity region can be enlarged by using relay, i.e., the capacity and fairness tradeoff relationship is alleviated. To achieve the Pareto-efficient boundary of this enlarged capacity region, an appropriate scheduling algorithm should be developed. Thus, second, we propose a generalized opportunistic scheduling algorithm for relaying mode that can improve both capacity and fairness. Furthermore, we propose a heuristic algorithm with low complexity and signaling overhead for relaying mode. Extensive simulations under various configurations demonstrate that the proposed algorithm not only increases the throughput of each user but also effectively alleviates unfairness among users.\",\n \"Title: Scheduling and Source Control with Average Queue-Length Control in Cellular Networks\\nYear: 2007\\n\\nAbstract: In this paper, a scheduling problem is considered in the cellular network where there exist CBR (constant bit rate) users requiring exact minimum average throughput and delay guarantee, and EMG (elastic with minimum guarantee) users requiring minimum average throughput and delay guarantee and more throughput if possible. We first define a new utility function of average queue length. Based on the new queue utility function and the throughput utility function proposed before, we design a 2-dimensional weight function that will be used in our scheduling algorithm, and suggest a source control algorithm that can work with the scheduling algorithm. We show through simulations that the proposed algorithm guarantees the QoS (quality of service) requirements of CBR and EMG users.\",\n \"Title: Commoncode: a code-reuse platform for wireless network experimentation\\nYear: 2012\\n\\nAbstract: Experimentation of a wireless network protocol over the air is of significant interest. However, it is more rarely performed than simulation because of the difficulties in coding and debugging as well as lack of scalability and repeatability. In this article, the concept of a code-reuse platform making use of a simulation code directly for real experiments is revisited as an efficient and easy means of experimentation. Furthermore, an architecture and key components of an idealistic code-reuse platform are suggested, and then CommonCode, the most advanced codereuse platform, is proposed. Through extensive simulations and experiments using Common-Code for the same codes, we demonstrate that CommonCode is valid and accurate in terms of protocol performance, and simultaneously fast and easy in terms of protocol development.\",\n \"Title: Dynamic bandwidth allocation schemes to improve utilization under nonuniform traffic in Ethernet passive optical networks\\nYear: 2004\\n\\nAbstract: In this paper, conventional bandwidth allocation schemes in ethernet passive optical network (EPON) are shown to suffer from poor utilization under the nonuniform traffic, particularly as the number of ONUs, guard time and round-trip time increase. To resolve this problem, we propose a new scheme which intelligently allocates a timeslot in consideration of other ONUs' queue occupancy, instead of strictly enforcing maximum timeslot size. The analysis and simulation results show that the proposed scheme can provide significantly higher utilization than the conventional schemes and support max-min fairness under the nonuniform traffic.\",\n \"Title: Predictive dynamic bandwidth allocation for efficient transport of real-time VBR video over ATM\\nYear: 1995\\n\\nAbstract: This paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. Video traffic statistics are measured in the frequency domain. The low-frequency signal captures the slow time-variation of consecutive scene changes while the high-frequency signal exhibits the feature of strong frame autocorrelation. Our queueing study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low-frequency signal. We further observe in typical JPEG/MPEG video sequences that the time scale of video scene changes is in the range of a second or longer, which localizes the low-frequency video signal in a well-defined low-frequency band. Hence, in a network design it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: recursive least square method and time delay neural network method. A time delay neural network with low-complexity high-order architecture, called “pi-sigma network,” is successfully used to predict scene changes. The overall dynamic bandwidth-allocation scheme presented is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic\",\n \"Title: Improving TCP Performance over Optimal CSMA in Wireless Multi-Hop Networks\\nYear: 2012\\n\\nAbstract: Optimal CSMA (oCSMA) has been receiving extensive attentions for its provable optimality in throughput and fairness without message passing over wireless multi-hop networks. However, recent studies suggest that TCP over oCSMA performs poorly, hindering the deployment of oCSMA in real networks. In this letter, we show that just a simple, additional virtual queue at the MAC layer can significantly improve TCP performance when oCSMA is used as the underlying MAC. Through testbed-based experiments, we demonstrate that with our virtual queueing scheme, TCP flows achieve near-optimal throughput performance in various scenarios.\",\n \"Title: Distributed max-min flow control for multi-rate overlay multicast\\nYear: 2010\\n\\nAbstract: We present a distributed algorithm to compute bandwidth max–min fair rates in an overlay multicast network supporting multi-rate data delivery. The proposed algorithm is scalable in that it does not require each logical link to maintain the saturation status of all sessions and virtual sessions traveling through it, stable in that it converges asymptotically to the desired equilibrium satisfying the minimum plus max–min fairness even in the presence of heterogeneous round-trip delays, and has explicit link buffer control in that the buffer occupancy of every bottlenecked link in the network asymptotically converges to the pre-defined value. The algorithm is based on PI (proportional integral) control in the feedback control theory and by appealing to the Nyquist stability criterion, a usable stability condition is derived in the presence of sources with heterogeneous round-trip delays. In addition, we propose an efficient feedback consolidation algorithm which is computationally simpler than its hard-synchronization based counterpart and eliminates unnecessary consolidation delay by preventing it from awaiting backward control packets that do not directly contribute to the session rate. Through simulations we further verify the analytical results and the performance of the proposed multi-rate multicast flow control scheme based on these two algorithms.\",\n \"Title: Dynamic association for load balancing and interference avoidance in multi-cell networks\\nYear: 2007\\n\\nAbstract: Next-generation cellular networks will provide higher cell capacity by adopting advanced physical layer techniques and broader bandwidth. Even in such networks, boundary users would suffer from low throughput due to severe intercell interference and unbalanced user distributions among cells, unless additional schemes to mitigate this problem are employed. In this paper, we tackle this problem by jointly optimizing partial frequency reuse and load-balancing schemes in a multicell network. We formulate this problem as a network-wide utility maximization problem and propose optimal offline and practical online algorithms to solve this. Our online algorithm turns out to be a simple mixture of inter- and intra-cell handover mechanisms for existing users and user association control and cell-site selection mechanisms for newly arriving users. A remarkable feature of the proposed algorithm is that it uses a notion of expected throughput as the decision making metric, as opposed to signal strength in conventional systems. Extensive simulations demonstrate that our online algorithm can not only closely approximate network-wide proportional fairness but also provide two types of gain, interference avoidance gain and load balancing gain, which yield 20~100% throughput improvement of boundary users (depending on traffic load distribution), while not penalizing total system throughput.We also demonstrate that this improvement cannot be achieved by conventional systems using universal frequency reuse and signal strength as the decision making metric.\",\n \"Title: Feedback Reduction for Multiuser OFDM Systems\\nYear: 2010\\n\\nAbstract: Feedback reduction in multiuser orthogonal frequency-division multiplexing (OFDM) systems has become an important issue due to the excessive amount of feedback required to use opportunistic scheduling, particularly when the number of users and carriers is large. In this paper, we propose a novel feedback-reduction scheme for efficient downlink scheduling. In the proposed scheme, each user determin...\",\n \"Title: Feedback Reduction for Multiuser OFDM Systems\\nYear: 2010\\n\\nAbstract: Feedback reduction in multiuser orthogonal frequency-division multiplexing (OFDM) systems has become an important issue due to the excessive amount of feedback required to use opportunistic scheduling, particularly when the number of users and carriers is large. In this paper, we propose a novel feedback-reduction scheme for efficient downlink scheduling. In the proposed scheme, each user determin...\",\n \"Title: Probabilistic burstiness-curve-based connection control for real-time multimedia services in ATM networks\\nYear: 1997\\n\\nAbstract: In this paper we present a method to establish real-time connections with guaranteed quality of service (QOS), based on a per-session probabilistic burstiness curve (PBC). Under two distinctive service disciplines, role proportional processor sharing and fixed rate processor sharing, we derive useful probabilistic bounds on per-session end-to-end loss which is caused by either buffer overflow in the path or excessive delay to the destination. One remarkable feature of the bounding solutions is that they are solely determined by the PBC of each session itself, independent of the network environment and other connections. To improve network resource utilization, our method is extended to allow statistical sharing of buffer resources. The admission control scheme presented in this paper has a great flexibility in connection management since bandwidth and buffer allocations can be adaptively adjusted among incoming and existing sessions according to present network resource availability. We also present a novel method to compute the PBC of multimedia traffic based on the measurement of two important statistics (rate histogram and power spectrum). Our study of MPEG/JPEG video sequences reveals the fundamental interrelationship among the PBC, the traffic statistics, and the QOS guarantee, and also provides many engineering aspects of the PBC approach to real-time multimedia services in ATM networks\",\n \"Title: Energy-optimal collaborative GPS localization with short range communication\\nYear: 2013\\n\\nAbstract: The key issue of the localization study is that how we can minimize the energy consumption of devices with guaranteeing high degree of accuracy. In this paper, we show that the collaboration among proxy devices with short range communication is helpful to energy-efficiently localize their locations in time-average sense by analyzing the device proximity including real GPS trace of students in KAIST and NCSU campuses. Next, we deliberate what is the best method for selfish mobile users to collaborate for the energy-efficient localization, and formulate an optimization problem which considers the energy efficiency and/or user fairness. However, optimizing this problem is tricky since it requires a global knowledge of sets of proxy devices and also solving a NP-hard problem to select devices which directly measure locations. This paper makes a contribution towards presenting a practical and fully distributed location sharing protocol based on competition for turning off GPS, and an optimal algorithm which controls mean waiting time used for the competition. Through the extensive simulations under several sample topologies and real mobility trace in KAIST campus, we obtain the following interesting observations: (i) (in sample topologies) our scheme achieves a near-optimal performance of proposed problem in terms of energy efficiency and fairness (up to 27.2% power saving with 35.8% higher fairness than existing heuristic algorithms), (ii) (in real mobility trace) our scheme well adapts at even unpredictably changing mobility environment (65.5% power saving than no collaboration, 27.4% or more power saving with 25% higher fairness than the existing algorithms).\",\n \"Title: WiOpt - general chair's message.\\nYear: 2009\\n\\nAbstract: Welcome to Seoul and welcome to the Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), the intellectual hub and melting pot of ideas from researchers and ractitioners interested in all aspects of modeling and optimization of wireless communication, ad hoc and mobile networking.\",\n \"Title: Wi-Fi sensing: Should mobiles sleep longer as they age?\\nYear: 2013\\n\\nAbstract: An essential condition precedent to the success of mobile applications based on Wi-Fi (e.g., iCloud) is an energy-efficient Wi-Fi sensing. From a user's perspective, a good WiFi sensing policy should depend on both inter-AP arrival and contact duration time distributions. Prior work focuses on limited cases of those two distributions (e.g., exponential) or introduces heuristic approaches such as AI (Additive Increase). In this paper, we formulate a functional optimization problem on Wi-Fi sensing under general inter-AP and contact duration distributions, and propose how each user should sense Wi-Fi APs to strike a balance between energy efficiency and performance, depending on the users' mobility pattern. To that end, we derive an optimal condition which sheds insights into the aging property, the key feature required by efficient Wi-Fi sensing polices. Guided by the analytical studies and the implications, we develop a new sensing algorithm, called WiSAG (Wi-Fi Sensing with AGing), which is demonstrated to outperform the existing sensing algorithms up to 34% through extensive trace-driven simulations using the real mobility traces gathered from smartphones.\",\n \"Title: Opportunistic underlay transmission in multi-carrier cognitive radio systems\\nYear: 2009\\n\\nAbstract: Underlay transmission in cognitive radio enables a secondary (unlicensed) system to utilize a frequency band of primary (licensed) system as long as the unlicensee interferes less than a certain threshold with the licensee. The secondary system needs to carefully consider not only its own channel to achieve a capacity gain by this sharing spectrum in multi-carrier systems, but also the interference channel to reduce interference at the primary receiver. In this paper, we formulate a capacity maximization problem of the secondary system under an interference-power constraint as well as a conventional transmit-power constraint, and propose an optimal power allocation policy in which we exploit a two-dimensional frequency-selectivity on both channels. Through extensive simulations, we compare the performance of optimal power allocation policy with that of equal power allocation policy and further investigate the effect of the primary's power allocation policy on the performance of the secondary system. Numerical results show that the optimal power allocation policy can achieve a higher capacity in more frequency-selective channels, compared to an equal power allocation policy. Interestingly, a water-filling policy for the primary system also gives additional opportunities to the secondary system than the equal power allocation policy.\",\n \"Title: Dual-Resource TCP/AQM for Processing-Constrained Networks\\nYear: 2008\\n\\nAbstract: This paper examines congestion control issues for TCP flows that require in-network processing on the fly in network elements such as gateways, proxies, firewalls and even routers. Applications of these flows are increasingly abundant in the future as the Internet evolves. Since these flows require use of CPUs in network elements, both bandwidth and CPU resources can be a bottleneck and thus congestion control must deal with ldquocongestionrdquo on both of these resources. In this paper, we show that conventional TCP/AQM schemes can significantly lose throughput and suffer harmful unfairness in this environment, particularly when CPU cycles become more scarce (which is likely the trend given the recent explosive growth rate of bandwidth). As a solution to this problem, we establish a notion of dual-resource proportional fairness and propose an AQM scheme, called Dual-Resource Queue (DRQ), that can closely approximate proportional fairness for TCP Reno sources with in-network processing requirements. DRQ is scalable because it does not maintain per-flow states while minimizing communication among different resource queues, and is also incrementally deployable because of no required change in TCP stacks. The simulation study shows that DRQ approximates proportional fairness without much implementation cost and even an incremental deployment of DRQ at the edge of the Internet improves the fairness and throughput of these TCP flows. Our work is at its early stage and might lead to an interesting development in congestion control research.\",\n \"Title: On the Critical Delays of Mobile Networks Under Lévy Walks and Lévy Flights\\nYear: 2011\\n\\nAbstract: Delay-capacity tradeoffs for mobile networks have been analyzed through a number of research works. However, Lévy mobility known to closely capture human movement patterns has not been adopted in such work. Understanding the delay-capacity tradeoff for a network with Lévy mobility can provide important insights into understanding the performance of real mobile networks governed by human mobility. This paper analytically derives an important point in the delay-capacity tradeoff for Lévy mobility, known as the critical delay. The critical delay is the minimum delay required to achieve greater throughput than what conventional static networks can possibly achieve (i.e., O(1/√n) per node in a network with n nodes). The Lévy mobility includes Lévy flight and Lévy walk whose step-size distributions parametrized by α ∈ (0,2] are both heavy-tailed while their times taken for the same step size are different. Our proposed technique involves: 1) analyzing the joint spatio-temporal probability density function of a time-varying location of a node for Lévy flight, and 2) characterizing an embedded Markov process in Lévy walk, which is a semi-Markov process. The results indicate that in Lévy walk, there is a phase transition such that for α ∈ (0,1), the critical delay is always Θ(n[1/2]), and for α ∈ [1,2] it is Θ(n[(α)/2]). In contrast, Lévy flight has the critical delay Θ(n[(α)/2]) for α ∈ (0,2].\",\n \"Title: Capacity of interference-limited ad hoc networks with infrastructure support\\nYear: 2006\\n\\nAbstract: In this letter, we consider the capacity of ad hoc networks with infrastructure support. Although Grossglauser-Tse mobile network model enables /spl Theta/(1) per-node throughput scaling, the mobility assumption may be too unrealistic to be accepted in some practical situations. One of the key observations we acquired is that the infrastructure support plays the same role played by the mobility in the Grossglauser-Tse model. We show that nodes can utilize the randomly located infrastructure support instead of mobility when nodes are nearly static. In this case, we show that the per-node throughput of /spl Theta/(1) is still achievable when the number of access points grows linearly with respect to the number of nodes.\",\n \"Title: Delay-optimal data forwarding in Vehicular Sensor Networks\\nYear: 2013\\n\\nAbstract: Vehicular Sensor Network (VSN) is emerging as a new solution for monitoring urban environments such as Intelligent Transportation Systems and air pollution. One of the crucial factors that determine the service quality of urban monitoring applications is the delivery delay of sensing data packets in the VSN. In this paper, we study the problem of routing data packets with minimum delay in the VSN, by exploiting i) vehicle traffic statistics, ii) anycast routing and iii) knowledge of future trajectories of vehicles such as buses. We first introduce a novel road network graph model that incorporates the three factors into the routing metric. We then characterize the packet delay on each edge as a function of the vehicle density, speed and the length of the edge. Based on the network model and delay function, we formulate the packet routing problem as a Markov Decision Process (MDP) and develop an optimal routing policy by solving the MDP. Evaluations using real vehicle traces in a city show that our routing policy significantly improves the delay performance compared to existing routing protocols.\",\n \"Title: Economics of WiFi offloading: Trading delay for cellular capacity\\nYear: 2013\\n\\nAbstract: Cellular networks are facing severe traffic overloads due to the proliferation of smart handheld devices and traffic-hungry applications. A cost-effective and practical solution is to offload cellular data through WiFi. Recent theoretical and experimental studies show that a scheme, referred to as delayed WiFi offloading, can significantly save the cellular capacity by delaying users' data and exploiting mobility and thus increasing chance of meeting WiFi APs (Access Points). Despite a huge potential of WiFi offloading in alleviating mobile data explosion, its success largely depends on the economic incentives provided to users and network providers to deploy and use delayed offloading. In this paper, we study how much economic benefits can be generated due to delayed WiFi offloading, by modeling the interaction between a single provider and users based on a two-stage sequential game. We first analytically prove that WiFi offloading is economically beneficial for both the provider and users. Also, we conduct trace-driven numerical analysis to quantify the practical gain, where the increase ranges from 21 to 152% in the provider's revenue, and from 73 to 319% in the users' surplus.\",\n \"Title: Delay-capacity tradeoffs for mobile networks with Lévy walks and Lévy flights\\nYear: 2011\\n\\nAbstract: This paper analytically derives the delay-capacity tradeoffs for Lévy mobility: Lévy walks and Lévy flights. Lévy mobility is a random walk with a power-law flight distribution. α is the power-law slope of the distribution and 0 <;; α ≤ 2. While in Lévy flight, each flight takes a constant flight time, in Lévy walk, it has a constant velocity which incurs strong spatio-temporal correlation as flight time depends on traveling distance. Lévy mobility is of special interest because it is known that Lévy mobility and human mobility share several common features including heavy-tail flight distributions. Humans highly influence the mobility of nodes (smartphones and cars) in real mobile networks as they carry or drive mobile nodes. Understanding the fundamental delay-capacity tradeoffs of Lévy mobility provides important insight into understanding the performance of real mobile networks. However, its power-law nature and strong spatio-temporal correlation make the scaling analysis non-trivial. This is in contrast to other random mobility models including Brownian motion, random waypoint and i.i.d. mobility which are amenable for a Markovian analysis. By exploiting the asymptotic characterization of the joint spatio-temporal probability density functions of Lévy models, the order of critical delay, the minimum delay required to achieve more throughput than Θ(1/√n) where n is the number of nodes in the network, is obtained. The results indicate that in Lévy walk, there is a phase transition that for 0 <; α <; 1, the critical delay is constantly Θ(n1/2) and for 1 ≤ α ≤ 2, is Θ(nα/2). In contrast, Lévy flight has critical delay Θ(nα/2) for 0 <; α ≤ 2.\",\n \"Title: A Video Traffic Model Based on the Shifting-Level Process: the Effects of SRD and LRD on Queueing Behavior\\nYear: 2000\\n\\nAbstract: Recently, a number of empirical studies havedemonstrated the existence of long-range dependence(LRD) or self-similarity in VBR video traffic. Since previousLRD models cannot capture all short- and long-term correlationand rate-distribution while still retaining mathematicaltractability, there exist many doubts on the importanceof SRD, LRD, and rate-distribution on traffic engineering.In this paper, we present a video traffic model basedon the shifting-level (SL) process with an...\",\n \"Title: Designing stable ABR flow control with rate feedback and open-loop control: first-order control case\\nYear: 1998\\n\\nAbstract: In this paper we present a control-theoretic approach to design stable rate-based flow control for ATM ABR services. The flow control algorithm that we consider has the most simple form among all the queue-length-based flow control algorithms, and is referred to as first-order rate-based flow control (FRFC) since the corresponding closed loop can be modeled as a first-order retarded differential equation. We analyze the equilibrium and the asymptotic stability of the closed loop for the case of multiple connections with diverse round-trip delays. We also characterize the asymptotic decay rate at which the stable closed loop tends to the equilibrium. The decay rate is shown to be a concave function of control gain with its maximum being the inverse of round-trip delay. We also consider an open loop control in which the queue control threshold is dynamically adjusted according to the changes in the available bandwidth and the number of connections. This open loop control is shown to be necessary and effective to prevent the closed loop from converging to an undesirable equilibrium point.\",\n \"Title: REFIM: A Practical Interference Management in Heterogeneous Wireless Access Networks\\nYear: 2011\\n\\nAbstract: Due to the increasing demand of capacity in wireless cellular networks, the small cells such as pico and femto cells are becoming more popular to enjoy a spatial reuse gain, and thus cells with different sizes are expected to coexist in a complex manner. In such a heterogeneous environment, the role of interference management (IM) becomes of more importance, but technical challenges also increase,...\",\n \"Title: Routing performance analysis of human-driven delay tolerant networks using the truncated levy walk model\\nYear: 2008\\n\\nAbstract: The routing performance of delay tolerant networks (DTN) is highly correlated with the distribution of inter-contact times (ICT), the time period between two successive contacts of the same two mobile nodes. As humans are often carriers of mobile communication devices, studying the patterns of human mobility is an essential tool to understand the performance of DTN protocols. From measurement studies of human contact behaviors, we find that their distributions closely resemble a form of power-law distributions called truncated Pareto. Human walk traces has a dichotomy distribution pattern of ICT; it has a power-law tendency up to some time, and decays exponentially after that time. Truncated Pareto distributions offer a simple yet cohesive mathematical model to express this dichotomy in the measured data. Using the residual and relaxation time theory [17] [4], we apply truncated Pareto distributions to quantify the performance of opportunistic routing in DTN. We further show that Truncated Levy walk (TLW) mobility model [22] commonly used in biology to describe the foraging patterns of animals [25], provide the same truncated power-law ICT distributions as observed from the empirical data, especially when mobility is confined within a finite area. This result confirms our recent finding that human walks contain similar statistical characteristics as Levy walks [22].\",\n \"Title: TCP-friendly flow control of wireless multimedia using ECN marking\\nYear: 2004\\n\\nAbstract: In a wireless network packet losses can be caused not only by network congestion but also by unreliable error-prone wireless links. Therefore, flow control schemes which use packet loss as a congestion measure cannot be directly applicable to a wireless network because there is no way to distinguish congestion losses from wireless losses. In this paper, we extend the so-called TCP-friendly flow control scheme, which was originally developed for the flow control of multimedia flows in a wired IP network environment, to a wireless environment. The main idea behind our scheme is that by using explicit congestion notification (ECN) marking in conjunction with random early detection (RED) queue management scheme intelligently, it is possible that not only the degree of network congestion is notified to multimedia sources explicitly in the form of ECN-marked packet probability but also wireless losses are hidden from multimedia sources. We calculate TCP-friendly rate based on ECN-marked packet probability instead of packet loss probability, thereby effectively eliminating the effect of wireless losses in flow control and thus preventing throughput degradation of multimedia flows travelling through wireless links. In addition, we refine the well-known TCP throughput model which establishes TCP-friendliness of multimedia flows in a way that the refined model provides more accurate throughput estimate of a TCP flow particularly when the number of TCP flows sharing a bottleneck link increases. Through extensive simulations, we show that the proposed scheme indeed improves the quality of the delivered video significantly while maintaining TCP-friendliness in a wireless environment for the case of wireless MPEG-4 video.\",\n \"Title: On the Levy-Walk Nature of Human Mobility\\nYear: 2011\\n\\nAbstract: We report that human walk patterns contain statistically similar features observed in Levy walks. These features include heavy-tail flight and pause-time distributions and the super-diffusive nature of mobility. Human walks are not random walks, but it is surprising that the patterns of human walks and Levy walks contain some statistical similarity. Our study is based on 226 daily GPS traces collected from 101 volunteers in five different outdoor sites. The heavy-tail flight distribution of human mobility induces the super-diffusivity of travel, but up to 30 min to 1 h due to the boundary effect of people's daily movement, which is caused by the tendency of people to move within a predefined (also confined) area of daily activities. These tendencies are not captured in common mobility models such as random way point (RWP). To evaluate the impact of these tendencies on the performance of mobile networks, we construct a simple truncated Levy walk mobility (TLW) model that emulates the statistical features observed in our analysis and under which we measure the performance of routing protocols in delay-tolerant networks (DTNs) and mobile ad hoc networks (MANETs). The results indicate the following. Higher diffusivity induces shorter intercontact times in DTN and shorter path durations with higher success probability in MANET. The diffusivity of TLW is in between those of RWP and Brownian motion (BM). Therefore, the routing performance under RWP as commonly used in mobile network studies and tends to be overestimated for DTNs and underestimated for MANETs compared to the performance under TLW.\",\n \"Title: First-order rate-based flow control with dynamic queue threshold for high-speed wide-area ATM networks.\\nYear: 1998\\n\\nAbstract: In this paper we present a new rate-based flow control scheme for ATM ABR services and analyze its performance. The proposed algorithm, which we refer to as first-order rate-based flow control (FRFC) is the most simple form of queue-length-based flow control. The asymptotic stability, the steady-state throughput, queue length and fairness, and the transient behavior are analyzed for the case of multiple connections with diverse round-trip delays. We also consider a novel approach to dynamically adjust a queue threshold in the FRFC according to the changes in the available bandwidth, and the arrival and departure of connections. Simulations show that the simple FRFC with dynamic queue threshold (DQT) effectively maintains high throughput, small loss and a desired fairness in these dynamic environments and is a promising solution for ABR flow control in ATM networks.\",\n \"Title: SLAW: self-similar least-action human walk\\nYear: 2012\\n\\nAbstract: Many empirical studies of human walks have reported that there exist fundamental statistical features commonly appearing in mobility traces taken in various mobility settings. These include: 1) heavy-tail flight and pause-time distributions; 2) heterogeneously bounded mobility areas of individuals; and 3) truncated power-law intercontact times. This paper reports two additional such features: a) The destinations of people (or we say waypoints) are dispersed in a self-similar manner; and b) people are more likely to choose a destination closer to its current waypoint. These features are known to be influential to the performance of human-assisted mobility networks. The main contribution of this paper is to present a mobility model called Self-similar Least-Action Walk (SLAW) that can produce synthetic mobility traces containing all the five statistical features in various mobility settings including user-created virtual ones for which no empirical information is available. Creating synthetic traces for virtual environments is important for the performance evaluation of mobile networks as network designers test their networks in many diverse network settings. A performance study of mobile routing protocols on top of synthetic traces created by SLAW shows that SLAW brings out the unique performance features of various routing protocols.\",\n \"Title: CommonCode: a code reuse platform for co-simulation and experimentation\\nYear: 2010\\n\\nAbstract: Experimentation of a wireless network protocol over the air is of significant interest. However it is rarely performed compared to the simulation because of the difficulties in coding and debugging as well as scalability and repeatability. CommonCode is a unique protocol validation platform reusing the simulation codes for the experiments. It helps fast, convenient and accurate validation of protocols.\",\n \"Title: Mobile Data Offloading: How Much Can WiFi Deliver?\\nYear: 2010\\n\\nAbstract: This paper presents a quantitative study on the performance of 3G mobile data offloading through WiFi networks. We recruited 97 iPhone users from metropolitan areas and collected statistics on their WiFi connectivity during a two-and-a-half-week period in February 2010. Our trace-driven simulation using the acquired whole-day traces indicates that WiFi already offloads about 65% of the total mobile data traffic and saves 55% of battery power without using any delayed transmission. If data transfers can be delayed with some deadline until users enter a WiFi zone, substantial gains can be achieved only when the deadline is fairly larger than tens of minutes. With 100-s delays, the achievable gain is less than only 2%-3%, whereas with 1 h or longer deadlines, traffic and energy saving gains increase beyond 29% and 20%, respectively. These results are in contrast to the substantial gain (20%-33%) reported by the existing work even for 100-s delayed transmission using traces taken from transit buses or war-driving. In addition, a distribution model-based simulator and a theoretical framework that enable analytical studies of the average performance of offloading are proposed. These tools are useful for network providers to obtain a rough estimate on the average performance of offloading for a given WiFi deployment condition.\",\n \"Title: Mobile data offloading: how much can WiFi deliver?\\nYear: 2013\\n\\nAbstract: This paper presents a quantitative study on the performance of 3G mobile data offloading through WiFi networks. We recruited 97 iPhone users from metropolitan areas and collected statistics on their WiFi connectivity during a two-and-a-halfweek period in February 2010. Our trace-driven simulation using the acquired whole-day traces indicates that WiFi already offloads about 65% of the total mobile data traffic and saves 55% of battery power without using any delayed transmission. If data transfers can be delayed with some deadline until users enter a WiFi zone, substantial gains can be achieved only when the deadline is fairly larger than tens of minutes. With 100-s delays, the achievable gain is less than only 2%-3%, whereas with 1 h or longer deadlines, traffic and energy saving gains increase beyond 29% and 20%, respectively. These results are in contrast to the substantial gain (20%-33%) reported by the existing work even for 100-s delayed transmission using traces taken from transit buses or war-driving. In addition, a distribution model-based simulator and a theoretical framework that enable analytical studies of the average performance of offloading are proposed. These tools are useful for network providers to obtain a rough estimate on the average performance of offloading for a given WiFi deployment condition.\",\n \"Title: Deterministic packet marking for max-min flow control\\nYear: 2005\\n\\nAbstract: This letter proposes a deterministic packet marking scheme that estimates the maximum link price on a communication path. The proposed scheme is simple and IP-compatible because it uses two-bit explicit congestion notification (ECN) field and IP identification (IPid) field in the standard IP header for the estimation. Through simulations using real IP packet traces, we show that our scheme indeed works as designed with small estimation errors, and thus enables existing max-min flow control algorithms to serve their purpose without the need of separate out-of-band control packets to carry link prices.\",\n \"Title: Max Contribution: An Online Approximation of Optimal Resource Allocation in Delay Tolerant Networks\\nYear: 2015\\n\\nAbstract: In this paper, a joint optimization of link scheduling, routing and replication for delay-tolerant networks (DTNs) has been studied. The optimization problems for resource allocation in DTNs are typically solved using dynamic programming which requires knowledge of future events such as meeting schedules and durations. This paper defines a new notion of approximation to the optimality for DTNs, called snapshot approximation where nodes are not clairvoyant, i.e., not looking ahead into future events, and thus decisions are made using only contemporarily available knowledges. Unfortunately, the snapshot approximation still requires solving an NP-hard problem of maximum weighted independent set (MWIS) and a global knowledge of who currently owns a copy and what their delivery probabilities are. This paper proposes an algorithm, Max-Contribution (MC) that approximates MWIS problem with a greedy method and its distributed online approximation algorithm, Distributed Max-Contribution (DMC) that performs scheduling, routing and replication based only on locally and contemporarily available information. Through extensive simulations based on real GPS traces tracking over 4,000 taxies and 500 taxies for about 30 days and 25 days in two different large cities, DMC is verified to perform closely to MC and outperform existing heuristically engineered resource allocation algorithms for DTNs.\",\n \"Title: Virtual Cell Beamforming in Cooperative Networks\\nYear: 2014\\n\\nAbstract: We study the coordinated transmission problem in cooperative cellular networks where a cluster of base stations forms a virtual cell to serve a mobile station (MS). The performance of such an MS-centric virtual cell network is dictated by the beamformer that enables to suppress interference; however, designing a beamformer is highly challenging due to the coupled nature of interference and desired signals under arbitrarily formed virtual cells. We develop a new formulation of the beamforming problem for sum-rate maximization in virtual cell networks and analyze the structure of its optimal solutions. Based on this analysis, we develop a beamforming algorithm that can balance between desired signal maximization and interference minimization, so as to maximize the sum-rate. We show through extensive simulations that our balanced beamforming algorithm mitigates edge user effect and outperforms existing algorithms in various scenarios where virtual cells are allowed to overlap.\",\n \"Title: Dynamic speed scaling for energy minimization in delay-tolerant smartphone applications\\nYear: 2014\\n\\nAbstract: Energy-delay tradeoffs in smartphone applications have been studied independently in dynamic voltage and frequency scaling (DVFS) problem and network interface selection problem. We optimize the two problems jointly to quantify how much energy can be saved further and propose a scheme called SpeedControl which jointly manages application scheduling, CPU speed control and wireless interface selection. The scheme is shown to be near-optimal in that it tends to minimize energy consumption for given delay constraints. This paper is the first to reveal energy-delay tradeoffs in a holistic view considering multiple wireless interfaces, DVFS and multitasking in smartphone. We perform real measurements on WiFi/3G coverage and throughput, power consumption of CPU and WiFi/3G interfaces, and CPU workloads. Trace-driven simulations based on the measurements demonstrate that SpeedControl can save over 30% of battery by trading 10 min delay as compared to existing schemes when WiFi temporal coverage is 65%, moreover, the saving tendency increases as WiFi coverage increases.\",\n \"Title: PhonePool: On energy-efficient mobile network collaboration with provider aggregation\\nYear: 2014\\n\\nAbstract: Energy consumption for cellular communication is increasingly gaining importance in smartphone battery lifetime as the bandwidth of wireless communication and the demand for mobile traffic increase. For energy-efficient cellular communication, we tackle two energy characteristics of cellular networks: (1) transmission energy highly varies upon channel condition, and (2) transmission of a packet accompanies unnecessary tail energy waste. Under the objective of transmitting packets when the best channel is provided as well as a number of packets are accumulated, we propose a new mobile collaboration framework “PhonePool” that aggregates smart devices across multiple cellular providers. Compared to the standalone operation, even without a buffering delay, PhonePool allows better channel and reduces more tail energy in a statistical point of view. To maximize the energy benefit while maintaining the fairness among the nodes in collaboration, we further develop a dynamic programming framework providing the optimal algorithm of PhonePool and its approximated heuristic. Trace-driven simulations on our experimental HSPA/EVDO/LTE network traces show that PhonePool of 5 devices achieves up to 42% of energy reduction.\",\n \"Title: CSMA-Based Robust AP Throughput Guarantee Under User Distribution Uncertainty\\nYear: 2015\\n\\nAbstract: We consider the problem of providing inter-access-point (AP) fairness guarantee in dense AP deployments where starvation can occur. In particular, we develop a framework for providing robust minimum throughput guarantee for each AP under the uncertainty of user distributions. Our framework consists of an AP throughput provisioning scheme and a distributed CSMA algorithm. The throughput provisioning scheme computes a robust feasible minimum AP throughput vector based on a random AP-level conflict graph and chance-constrained optimization. By incorporating the minimum throughput vector, we develop a distributed CSMA algorithm that fulfills the minimum requirement for each AP and is compatible with the IEEE 802.11 standard. We show through extensive simulations that our framework addresses the AP starvation problem by guaranteeing minimum throughput for each AP.\",\n \"Title: Seamless realtime traffic handover policy for IEEE 802.16m mobile WiMAX\\nYear: 2009\\n\\nAbstract: IEEE 802.16m standard is defining several improvements on IEEE 802.16e standard, one of them being handover (HO). This paper provides a policy to satisfy IEEE 802.16m benchmark of 150 msec or less for a hard handover (HO) between two base stations (BSs). To facilitate such fast HO, the target BSs are chosen before HO is sought. Such choice is made based on previously acquired knowledge of human mobility behavior. There are several initial ranging opportunities provided before the actual HO. Before the connection breaks with serving BS, target BS sets up its MAC states to allow instantaneous connection of service flows that are prevalent in the ongoing connection. Once the connection is broken, serving BS redirects the traffic to target BS while MSS, using the ranging parameters provided right before the connection breakup, initiates a connection request to the target BS. Several timers perform as check points so that critical operations are performed in timely manner.\",\n \"Title: DREAM: Dynamic Resource and Task Allocation for Energy Minimization in Mobile Cloud Systems\\nYear: 2015\\n\\nAbstract: To cope with increasing energy consumption in mobile devices, the mobile cloud offloading has received considerable attention from its ability to offload processing tasks of mobile devices to cloud servers, and previous studies have focused on single type tasks in fixed network environments. However, real network environments are spatio-temporally varying, and typical mobile devices have not only various types of tasks, e.g., network traffic, cloud offloadable/nonoffloadable workloads but also capabilities of CPU frequency scaling and network interface selection between WiFi and cellular. In this paper, we first jointly consider the following three dynamic problems in real mobile environments: 1) cloud offloading policy, i.e., determining to use local CPU resources or cloud resources; 2) allocation of tasks to transmit through networks and to process in local CPU; and 3) CPU clock speed and network interface controls. We propose a DREAM algorithm by invoking the Lyapunov optimization and mathematically prove that it minimizes CPU and network energy for given delay constraints. Trace-driven simulation based on real measurements demonstrates that DREAM can save over 35% of total energy than existing algorithms with the same delay. We also design DREAM architecture and demonstrate the applicability of DREAM in practice.\",\n \"Title: Dual-side dynamic controls for cost minimization in mobile cloud computing systems\\nYear: 2015\\n\\nAbstract: Mobile cloud computing (MCC) has been proposed to offload heavy computing jobs of mobile devices to cloud servers managed by cloud service provider (CSP), which enables the mobile devices to save energy and processing delay. Heretofore, cloud offloading policies in mobile devices and pricing/scheduling in CSP have been independently addressed. This paper is first to jointly account for both sides of mobile users and CSP in a unified mobile cloud computing framework. By invoking “Lyapunov drift-plus-penalty” technique, we propose dual-side control algorithms for the mobile users and CSP in two different scenarios: (i) In non-cooperation scenario, we propose a NC-UC algorithm for the mobile users and a NC-CC algorithm for the CSP to minimize each cost for given delay constraints. (ii) In cooperation scenario, we suggest a CP-JC algorithm for both cloud users and CSP to minimize the sum costs of them for given delay constraints. Trace-driven simulations demonstrate that NC-UC saves minimum 63% of cost by trading 8MB of average queue lengths when compared with the existing algorithms, and NC-CC achieves 71% of profit gain when compared with the same delay of existing scheme; moreover, the cooperation enables them to save additional costs and delays.\",\n \"Title: TAES: Traffic-aware energy-saving base station sleeping and clustering in cooperative networks\\nYear: 2015\\n\\nAbstract: We consider energy efficient base station sleeping and clustering problems in cooperative cellular networks where clusters of base stations jointly transmit to users. Our key idea of energy saving is to exploit a spatio-temporal fluctuation of traffic demand, which is to use minimal energy to provide capacity only slightly greater than varying traffic demand. Then, energy saving is possible without capacity loss. However, it is highly challenging to design traffic-aware algorithms without the future traffic demand information. To overcome this, we develop algorithms using queue instead of the future traffic information. For BS clustering problem, we propose an optimal algorithm that has polynomial complexity. For BS sleeping problem, which is a complex combinatorial problem, we propose two algorithms; One finds an optimal solution with reduced complexity compared to the exhaustive search, and the other finds a near-optimal solution with polynomial complexity. Through extensive simulations we show that the proposed algorithms can save significant energy when traffic load is low.\",\n \"Title: Opportunistic shortest path forwarding in delay tolerant networks\\nYear: 2010\\n\\nAbstract: Delay Tolerant Networks (DTNs) are characterized by probabilistic links formed among mobile nodes indicating their probabilistic encounters. Prior work on DTN routing uses expected delays as a routing metric to decide the next hop relay node for packet delivery to the destination. However, they measure the expected delays by taking the minimum of the expected delays over all possible paths from a candidate relay. This metric, denoted by MinEx, does not account for the opportunity gain enabled by having multiple paths to the destination through encountering multiple future neighbors. Since DTN routing uses as the relay the first encountered node satisfying given routing criteria, the random delays to multiple relay nodes should be aggregated. Thus, the true expected delays can be measured by taking the expectation of the minimum delays, denoted as ExMin, over all possible probabilistic paths from the candidate.\",\n \"Title: Practicalizing Delay-Tolerant Mobile Apps with Cedos\\nYear: 2015\\n\\nAbstract: Delay-tolerant Wi-Fi offloading is known to improve overall mobile network bandwidth at low delay and low cost. Yet, in reality, we rarely find mobile apps that fully support opportunistic Wi-Fi access. This is mainly because it is still challenging to develop delay-tolerant mobile apps due to the complexity of handling network disruptions and delays. In this work, we present Cedos, a practical delay-tolerant mobile network access architecture in which one can easily build a mobile app. Cedos consists of three components. First, it provides a familiar socket API whose semantics conforms to TCP while the underlying protocol, D2TP, transparently handles network disruptions and delays in mobility. Second, Cedos allows the developers to explicitly exploit delays in mobile apps. App developers can express maximum user-specified delays in content download or use the API for real-time buffer management at opportunistic Wi-Fi usage. Third, for backward compatibility to existing TCPbased servers, Cedos provides D2Prox, a protocol-translation Web proxy. D2Prox allows intermittent connections on the mobile device side, but correctly translates Web transactions with traditional TCP servers. We demonstrate the practicality of Cedos by porting mobile Firefox and VLC video streaming client to using the API. We also implement delay/disruption-tolerant podcast client and run a field study with 50 people for eight weeks. We find that up to 92.4% of the podcast traffic is offloaded to Wi-Fi, and one can watch a streaming video in a moving train while offloading 48% of the content to Wi-Fi without a single pause.\",\n \"Title: Energy-Efficient Wi-Fi Sensing Policy Under Generalized Mobility Patterns With Aging.\\nYear: 2016\\n\\nAbstract: An essential condition precedent to the success of mobile applications based on Wi-Fi e.g., iCloud is an energy-efficient Wi-Fi sensing. Clearly, a good Wi-Fi sensing policy should factor in both inter-access point AP arrival time IAT and contact duration time CDT distributions of each individual. However, prior work focuses on limited cases of those two distributions e.g., exponential or proposes heuristic approaches such as Additive Increase AI. In this paper, we first formulate a generalized functional optimization problem on Wi-Fi sensing under general inter-AP and contact duration distributions and investigate how each individual should sense Wi-Fi APs to strike a good balance between energy efficiency and performance, which is in turn intricately linked with users mobility patterns. We then derive a generic optimal condition that sheds insights into the aging property, underpinning energy-aware Wi-Fi sensing polices. In harnessing our analytical findings and the implications thereof, we develop a new sensing algorithm, called Wi-Fi Sensing with AGing WiSAG, and demonstrate that WiSAG outperforms the existing sensing algorithms up to 37% through extensive trace-driven simulations for which real mobility traces gathered from hundreds of smartphones is used.\",\n \"Title: Just-In-Time Wlans: On-Demand Interference-Managed Wlan Infrastructures\\nYear: 2016\\n\\nAbstract: In the past years, the centralized management of dense wireless local area networks has been emerged as a powerful paradigm for improving energy efficiency as well as avoiding severe interference. In this paper, we study the joint optimization on power-operation modes in access points (APs), channel selections and user-AP associations for improving energy efficiency and avoiding interference without sacrificing users' demands. To this end, we first formulate it as a mixed-integer programming using the popular Lyapunov approach, but it turns out to be computationally intractable, i.e., NP-hard. To address the issue, we propose a polynomial-time approximation algorithm and prove that it achieves a constant-factor approximation guarantee under mild assumptions. The main novelty underlying our algorithm design is based on a linear programming relaxation combining with two different greedy rounding schemes, where each achieves a constant-factor approximation in different regimes of parameters. We verify the performance of the proposed algorithm via extensive simulations and also demonstrate its practicability by implementing it at commercial APs using a Software-defined Networking framework, which shows that it reduces the wasted energy significantly while maintaining even higher throughput.\",\n \"Title: Resource-Efficient Mobile Multimedia Streaming With Adaptive Network Selection.\\nYear: 2016\\n\\nAbstract: From the advancements of mobile display and network infrastructure, mobile users can enjoy high quality mobile video streaming anywhere, anytime. However, most mobile users are still reluctant to use high quality video streaming when they are mobile due to costly cellular data and high energy consumption. In this work, we develop scheduling algorithms for resource-efficient mobile video streaming, which minimize the weighted sum objective of cellular cost and energy consumption. We first model the scheduling problem as a Markov decision process and propose an optimal scheduling algorithm based on dynamic programming. Then, we derive a heuristic algorithm that approximates the optimal algorithm. To evaluate the performance of proposed algorithms, we run simulation over YouTube video traces with audience retention graphs and mobility/connectivity traces in public transportation (e.g., commuting). Through extensive simulations, we show that our proposed scheduling algorithm has negligible performance loss compared to the optimal scheduling algorithm, where it saves 59% of cellular cost and 41% of energy compared to the YouTube default scheduler. We also implement our scheduling algorithm on an Android platform, and experimentally evaluate the performance compared to existing streaming policies.\",\n \"Title: TravelMiner: On the Benefit of Path-Based Mobility Prediction\\nYear: 2016\\n\\nAbstract: Mobility predictions are becoming more valuable in various applications with the rise of mobile devices. Given that existing prediction techniques are composed of two key procedures: 1) profiling past mobility trajectories as sequences of discrete atomic states (e.g., grid locations, semantic locations) and capturing them with an appropriate statistical model, 2) making a prediction on the next state using the statistical model, TravelMiner tackles the former with paths utilized as the atomic states for the first time, where the paths are defined as sub-trajectories with no branches. Comparing to available location-based predictors, TravelMiner makes a fundamental difference in that it is able to predict the sequence of paths rather than locations, which is far more detailed in the perspective of knowing the exact route to follow. TravelMiner enables this benefit by extracting disjoint paths from GPS trajectories via a similarity metric for curves, called Frechet distance and keeping the sequences of such paths in a statistical model, called probabilistic radix tree. Our extensive simulations over the GPS trajectories of 124 users reveal that TravelMiner outperforms other predictors in diverse popular performance metrics including predictability, prediction accuracy and prediction resolution.\",\n \"Title: Dynamic Pricing, Scheduling, and Energy Management for Profit Maximization in PHEV Charging Stations.\\nYear: 2017\\n\\nAbstract: Recently, as plug-in hybrid electric vehicles (PHEVs) take center stage for the eco-friendly and cost-effective transportation, commercial PHEV charging stations will be widely prevalent in the future. However, previous studies in the fields of the management of PHEV charging stations have not synthetically taken practical charging systems into account. In this paper, we study the profit-optimal m...\",\n \"Title: CarrierMix: How Much Can User-side Carrier Mixing Help?\\nYear: 2017\\n\\nAbstract: Energy consumption for cellular communication is increasingly gaining importance in smartphone battery lifetime as the bandwidth of wireless communication and the demand for mobile traffic increase. For energy-efficient cellular communication, we tackle two energy characteristics of cellular networks: (1) transmission energy highly varies upon channel condition, and (2) transmission of a packet accompanies unnecessary tail energy waste. Under the objective of transmitting packets when the best channel is provided as well as a number of packets are accumulated, we propose a new mobile collaboration framework “CarrierMix” that aggregates smart devices across multiple heterogeneous cellular carriers. Compared to the standalone operation, even without a buffering delay, CarrierMix allows better channel and reduces more tail energy in a statistical point of view. To maximize the energy benefit while maintaining the fairness among the nodes in collaboration, we further develop a dynamic programming framework providing the optimal algorithm of CarrierMix and its approximated heuristic. Trace-driven simulations on our experimental HSPA/EVDO/LTE network traces show that CarrierMix of five devices achieves up to 42 percent of energy reduction.\",\n \"Title: Cedos: A Network Architecture and Programming Abstraction for Delay-Tolerant Mobile Apps.\\nYear: 2017\\n\\nAbstract: Delay-tolerant Wi-Fi offloading is known to improve overall mobile network bandwidth at low delay and low cost. Yet, in reality, we rarely find mobile apps that fully support opportunistic Wi-Fi access. This is mainly because it is still challenging to develop delay-tolerant mobile apps due to the complexity of handling network disruptions and delays. In this paper, we present Cedos, a practical delay-tolerant mobile network access architecture in which one can easily build a mobile app. Cedos consists of three components. First, it provides a familiar socket API whose semantics conforms to TCP, while the underlying protocol, $\\\\\\\\text{D}^{2}$ TP, transparently handles network disruptions and delays in mobility. Second, Cedos allows the developers to explicitly exploit delays in mobile apps. App developers can express maximum user-specified delays in content download or use the API for real-time buffer management at opportunistic Wi-Fi usage. Third, for backward compatibility to existing TCP-based servers, Cedos provides $\\\\\\\\text{D}^{2}$ Prox, a protocol-translation Web proxy. $\\\\\\\\text{D}^{2}$ Prox allows intermittent connections on the mobile device side, but correctly translates Web transactions with traditional TCP servers. We demonstrate the practicality of Cedos by porting mobile Firefox and VLC video streaming client to using the API. We also implement delay/disruption-tolerant podcast client and run a field study with 50 people for eight weeks. We find that up to 92.4% of the podcast traffic is offloaded to Wi-Fi, and one can watch a streaming video in a moving train while offloading 48% of the content to Wi-Fi without a single pause.\",\n \"Title: Hybrid Content Caching For Low End-To-End Latency In Cloud-Based Wireless Networks\\nYear: 2017\\n\\nAbstract: In this paper, we consider the content caching design without requiring historical content access information or content popularity profiles in a hierarchical cellular network architecture. Our design aims to dynamically select caching locations for different contents where caching locations can be content servers, cloud units (CUs), and base stations (BSs). Our design objective is to support as high content request rates as possible while maintaining the finite service time. To tackle this design problem, we employ the Lyapunov optimization method where the caching algorithm is developed by minimizing the Lyapunov drift of a quadratic Lyapunov function of virtual queue backlogs. This solution approach requires to solve a max-weight problem, which is an NP-hard and difficult problem to solve due to the coupling between CU caching and BS caching decisions. By exploiting the submodularity of the objective function, we propose a hybrid caching algorithm which achieves the constant approximation ratio to the optimal performance. Trace-driven simulation results demonstrate that the proposed joint CU/BS caching algorithm achieves almost the same performance with the exhaustive search and outperforms the independent caching algorithm and heuristic joint caching algorithms in terms of average end-to-end latency and backhaul load reduction ratio.\",\n \"Title: Traffic-Aware Energy-Saving Base Station Sleeping and Clustering in Cooperative Networks.\\nYear: 2018\\n\\nAbstract: We consider energy efficient base station (BS) sleeping and clustering problems in cooperative cellular networks, where clusters of base stations jointly transmit to users. Our key idea of energy saving is to exploit spatio-temporal fluctuation of traffic demand, and use minimal energy to provide achievable data rate only slightly greater than varying traffic demand. However, it is highly challeng...\",\n \"Title: Capacity, fairness, and queueing performance analysis of opportunistic scheduling with one-bit feedback.\\nYear: 2018\\n\\nAbstract: In this paper, we consider opportunistic downlink scheduling in a cellular network that exploits multiuser diversity using one-bit feedback. To reduce the feedback overhead inherent in opportunistic scheduling, mobile stations are allowed to send one-bit information to the base station only when their channel quality exceeds a given threshold value. The objective of this paper is two-fold: (i) find the threshold value that can optimize queueing performance of the scheduler and (ii) investigate the relationship among capacity, fairness, and queueing performance. To this end, we first derive a formula for the sum-rate capacity as a function of the threshold. Next, we quantify the long-term and short-term fairness using Jain’s fairness index. Lastly, we develop a packet-level queueing model and derive QoS measures such as queueing delay and packet loss probability. Based on our analysis, we optimize the threshold value by considering both the traffic condition at the MAC layer and the temporal channel correlation at the PHY layer. Numerical results show that the optimized threshold can significantly reduce the average queueing delay and the packet loss probability. In addition, we find that there is a trade-off between short-term fairness and sum-rate capacity, whose control knob is the threshold. We show that, from a queueing performance perspective, supporting the sum-rate capacity (resp. the short-term fairness) is more important when the traffic is heavy (resp. light) or the wireless channel varies with low (resp. high) temporal correlation.\",\n \"Title: Dual-Side Optimization for Cost-Delay Tradeoff in Mobile Edge Computing.\\nYear: 2018\\n\\nAbstract: Mobile code offloading (MCO) is a technology that offloads computing tasks from mobile devices to remote servers managed by code offload service providers (CSPs). Nowadays, it is recommended that the remote servers be placed on the edge of the network to support modern applications, e.g., augmented reality, which demand stringent and ultralow latency or high bandwidth. To date, previous studies ha...\",\n \"Title: Control of multi-resource infrastructures: Application to NFV and computation offloading\\nYear: 2018\\n\\nAbstract: Network function virtualization (NFV) and Computation offloading (CO) are state-of-the-art technologies for flexible utilization of networking and processing resources. These two technologies are closely related in that they enable multiple physical entities to process a function provided in a service, and the service (or end host) chooses which resources to use. In this paper, we propose a generalized dual-resource system, which unifies NFV service and CO service frameworks, and formulate a multi-path problem for choosing resources to use in NFV and CO services. The problem is reformulated as a variational inequality by using Lagrange dual theory and saddle point theory. Based on this formulation, we propose an extragradient-based algorithm that controls and splits the sending rate of a service. We prove that the algorithm converges to an optimal point where system cost minus service utility is minimized. Simulations under diverse scenarios demonstrate that our algorithm achieves high quality of service while reducing the system cost by jointly considering dual-resource coupling and service characteristics.\",\n \"Title: Hybrid Content Caching in 5G Wireless Networks: Cloud Versus Edge Caching.\\nYear: 2018\\n\\nAbstract: Most existing content caching designs require accurate estimation of content popularity, which can be challenging in the dynamic mobile network environment. Moreover, emerging hierarchical network architecture enables us to enhance the content caching performance by opportunistically exploiting both cloud-centric and edge-centric caching. In this paper, we propose a hybrid content caching design t...\",\n \"Title: Learning based Utility Maximization for Multi-Resource Management: Poster Abstract.\\nYear: 2018\\n\\nAbstract: This poster addresses the problem of Network Utility Maximization (NUM) where multiple resources (computing/networking) participate in user services. NUM has usually been solved by Backpressure algorithms which has to build up queue size gradualy. This disadvantage stands out in the situation of multi-resource environment or multi-hop networking. To address the problem, we propose a reinforcement learning based algorithm that utilizes future prediction to overcome the previous limitation of non-learning based algorithms.\",\n \"Title: Unknown Flow Detection with Imbalanced Traffic Data: Poster Abstract.\\nYear: 2018\\n\\nAbstract: Unknown traffic is a serious problem in network traffic classification for network management and security, since it degrades the performance of a traffic classifier. We propose a machine learning-based classifier that can not only categorize the traffic of known classes but also detect unknown traffic in data imbalanced network environment, where frequency of traffic from one application outweighs that of other application. We improved the previous RTC model by adding data preprocessing module and simulated with synthesized dataset to show the effect of the data imbalance problem on classification accuracy and to validate the performance of our model in data-imbalanced network environment.\",\n \"Title: Mobile Computation Offloading for Application Throughput Fairness and Energy Efficiency\\nYear: 2019\\n\\nAbstract: Mobile computation offloading is emerging as a promising technology to enhance the computation power of mobile devices by borrowing processing resources from the cloud. However, using cloud resource is a double-edged sword because of the potentially enormous network energy consumption of mobile devices. In this paper, we study the mobile device resource management problem for application throughput fairness and energy efficiency in computation offloading environment. Our problem seeks to optimize task arrival rates, scheduling for local processing and offloading, CPU clock speed, and network interface selection, so as to maximize the energy-utility efficiency defined as achievable utility per unit energy consumption. The efficiency metric has a fractional form that is hard to deal with in general. To address this difficulty, we modify a general Lyapunov optimization technique and derive a series of short-term problems that change over time with respect to an unknown objective parameter. Then, we derive an offloading algorithm and prove that the algorithm maximizes the long-term energy-utility efficiency. Trace-driven simulations demonstrate that our algorithm achieves high-energy efficiency while maintaining throughput fairness among applications running on a mobile device.\",\n \"Title: Virtual Beamforming and User Scheduling for Sub-Array Architecture in mmWave Networks.\\nYear: 2019\\n\\nAbstract: In this letter, we propose a virtual beamforming and user scheduling technique, namely VirtualBus that attains higher beamforming gain by generating narrower beams in a sub-array mmWave network architecture. The proposed VirtualBus is beneficial as well in a sense that it does not increase the hardware complexity of the sub-array architecture. Through simulations on the practical scenario, we veri...\",\n \"Title: TCP-friendly wireless multimedia flow control using ECN marking\\nYear: 2002\\n\\nAbstract: In a wireless network, packet losses can be caused not only by network congestion but also by unreliable error-prone wireless links. Therefore, flow control schemes which use packet loss as a congestion measure cannot be directly applicable to a wireless network because congestion losses cannot be distinguished from wireless losses. We extend a so-called TCP-friendly flow control scheme, which was developed for the control of multimedia flows carried over UDP in the presence of TCP flows, to a wireless environment by using ECN (explicit congestion notification) marking capability with RED (random early detection) routers. By detecting congestion early, explicitly informing multimedia sources of congestion using ECN marking and calculating a TCP-friendly rate based on ECN-marked packet probability instead of packet loss probability, we are able effectively to separate the effect of wireless losses from flow control and thus prevent throughput degradation of multimedia flows traveling through wireless links. Also, we refine a well-known TCP throughput model developed for TCP-friendliness of multimedia flows such that the refined model provides more accurate estimate of TCP flows' throughput when both ECN marking and RED queue management are used. By simulation, we show that the proposed scheme does improve the quality of the delivered video significantly while maintaining TCP-friendliness for the case of wireless MPEG-4 video.\",\n \"Title: Routing, path computation and traffic engineering in future Internet.\\nYear: 2007\\n\\nAbstract: The current Internet architecture with integrated routing and forwarding planes has served the community well for the past three decades. The significant growth in Internet traffic and the need for support of very diverse sources has spurned research interest in new architectures. In particular, the next-generation Internet must cater to a variety of services with dynamically changing traffic demand and it is critical that it supports various quality of service (QoS) measures, to efficiently utilize network resources and to reduce operational costs.\",\n \"Title: Multi-flow management for mobile data offloading\\nYear: 2017\\n\\nAbstract: Cellular networks are facing explosive growth of mobile data traffic due to the proliferation of smart devices and traffic-intensive applications. As a cost-effective solution, delayed Wi-Fi offloading was introduced to shift the delay-tolerant traffic from cellular to Wi-Fi networks by trading additional delays. Our paper studies a multi-flow rate control problem where each flow has different traffic load and a deadline. To maximize user satisfaction defined as offloading efficiency minus disutility caused by deadline violation, we propose a dynamic programming-based rate control algorithm. Moreover, to reduce the computation and memory, we propose a simple threshold-based rate control algorithm.\",\n \"Title: Simplified Stochastic Feedforward Neural Networks.\\nYear: 2017\\n\\nAbstract: It has been believed that stochastic feedforward neural networks (SFNNs) have several advantages beyond deterministic deep neural networks (DNNs): they have more expressive power allowing multi-modal mappings and regularize better due to their stochastic nature. However, training large-scale SFNN is notoriously harder. In this paper, we aim at developing efficient training methods for SFNN, in particular using known architectures and pre-trained parameters of DNN. To this end, we propose a new intermediate stochastic model, called Simplified-SFNN, which can be built upon any baseline DNNand approximates certain SFNN by simplifying its upper latent units above stochastic ones. The main novelty of our approach is in establishing the connection between three models, i.e., DNN-u003eSimplified-SFNN-u003eSFNN, which naturally leads to an efficient training procedure of the stochastic models utilizing pre-trained parameters of DNN. Using several popular DNNs, we show how they can be effectively transferred to the corresponding stochastic models for both multi-modal and classification tasks on MNIST, TFD, CASIA, CIFAR-10, CIFAR-100 and SVHN datasets. In particular, we train a stochastic model of 28 layers and 36 million parameters, where training such a large-scale stochastic network is significantly challenging without using Simplified-SFNN\",\n \"Title: Practical dynamic interference management in multi-carrier multi-cell wireless networks: A reference user based approach\\nYear: 2010\\n\\nAbstract: In order to overcome low performance of conventional static interference management algorithms and high complexity of existing dynamic interference management algorithms, this paper proposes an efficient, low-complex and fully distributed power control and user scheduling algorithm in downlink multi-carrier multi-cell wireless networks. We decompose the original optimization problem, which requires intractable computation complexity for global optimality, into per-BS (base station) problems based on the notion of reference user. This idea is a good approximation of the optimal algorithms that permits significant complexity reduction, yet sustains near-optimal performance. We further reduce feedback overhead to make the resulting algorithm more practical by exploiting temporal correlations and spatial simplification. We verify the efficiency of our proposed algorithm through extensive simulations over various topologies and scenarios motivated by the current 3G BS deployment map.\",\n \"Title: Proximity-Aware Location Based Collaborative Sensing for Energy-Efficient Mobile Devices\\nYear: 2019\\n\\nAbstract: A fundamental question in the study of location-based mobile sensing is how much energy can be saved while still guaranteeing the reliable localization accuracy. In this paper, we analyze key features of human proximity and find a motivation which implies that the energy-efficient and accurate localization is possible by sharing the locations of nearby mobile devices. From the location-based collaborative sensing idea, we formulate an optimization problem which aims to minimize the total number of location measurements for a given fairness criterion. Then, we propose a practical and distributed location sharing (DLS) protocol and an optimal parameter control algorithm (OWD) which makes the DLS protocol attain an asymptotic optimal performance. Via extensive simulations under various environments including real mobility traces, we verify that the proposed DLS+OWD policy significantly reduces the average power consumption of mobile devices with a higher fairness compared to the existing algorithms.\",\n \"Title: Hardware-adaptive Efficient Latency Prediction for NAS via Meta-Learning.\\nYear: 2021\\n\\nAbstract: For deployment, neural architecture search should be hardware-aware, in order to satisfy the device-specific constraints (e.g., memory usage, latency and energy consumption) and enhance the model efficiency. Existing methods on hardware-aware NAS collect a large number of samples (e.g., accuracy and latency) from a target device, either builds a lookup table or a latency estimator. However, such approach is impractical in real-world scenarios as there exist numerous devices with different hardware specifications, and collecting samples from such a large number of devices will require prohibitive computational and monetary cost. To overcome such limitations, we propose Hardware-adaptive Efficient Latency Predictor (HELP), which formulates the device-specific latency estimation problem as a meta-learning problem, such that we can estimate the latency of a model's performance for a given task on an unseen device with a few samples. To this end, we introduce novel hardware embeddings to embed any devices considering them as black-box functions that output latencies, and meta-learn the hardware-adaptive latency predictor in a device-dependent manner, using the hardware embeddings. We validate the proposed HELP for its latency estimation performance on unseen platforms, on which it achieves high estimation performance with as few as 10 measurement samples, outperforming all relevant baselines. We also validate end-to-end NAS frameworks using HELP against ones without it, and show that it largely reduces the total time cost of the base NAS method, in latency-constrained settings.\",\n \"Title: zTT: learning-based DVFS with zero thermal throttling for mobile devices\\nYear: 2021\\n\\nAbstract: ABSTRACTDVFS (dynamic voltage and frequency scaling) is a system-level technique that adjusts voltage and frequency levels of CPU/GPU at runtime to balance energy efficiency and high performance. DVFS has been studied for many years, but it is considered still challenging to realize a DVFS that performs ideally for mobile devices for two main reasons: i) an optimal power budget distribution between CPU and GPU in a power-constrained platform can only be defined by the application performance, but conventional DVFS implementations are mostly application-agnostic; ii) mobile platforms experience dynamic thermal environments for many reasons such as mobility and holding methods, but conventional implementations are not adaptive enough to such environmental changes. In this work, we propose a deep reinforcement learning-based frequency scaling technique, zTT. zTT learns thermal environmental characteristics and jointly scales CPU and GPU frequencies to maximize the application performance in an energy-efficient manner while achieving zero thermal throttling. Our evaluations for zTT implemented on Google Pixel 3a and NVIDIA JETSON TX2 platform with various applications show that zTT can adapt quickly to changing thermal environments, consistently resulting in high application performance with energy efficiency. In a high-temperature environment where a rendering application with the default mobile DVFS fails to keep producing more than a target frame rate, zTT successfully manages to do so even with 23.9% less average power consumption.\",\n \"Title: Energy and Delay Guaranteed Joint Beam and User Scheduling Policy in 5G CoMP Networks\\nYear: 2022\\n\\nAbstract: Massive Multi-Input Multi-Output (MIMO) and Coordinated MultiPoint (CoMP) technologies in Cloud-RAN (C-RAN) architecture become inevitable trend due to the advent of next-generation mobile applications, which are traffic-intensive, such as ultra high definition (UHD) video. In this paper, we study a joint beam activation and user scheduling problem in a 5G cellular network with massive MIMO and Co...\",\n \"Title: R-FEC: RL-based FEC Adjustment for Better QoE in WebRTC\\nYear: 2022\\n\\nAbstract: ABSTRACTThe demand for video conferencing applications has seen explosive growth while users still often face unsatisfactory quality of experience (QoE). Video conferencing applications adopt Forward Error Correction (FEC) as a recovery mechanism to meet tight latency requirements and overcome packet losses prevalent in the network. However, many studies mainly focused on video rate control by neglecting the complex interactions of this video recovery mechanism on the rate control and its impact on the user QoE. Deciding the right amount of FEC for the current video rate under a dynamically changing network environment is not straightforward. For instance, the higher FEC may enhance the tolerance to packet losses, but it may increase latency due to FEC processing overhead and hurt the video quality due to the additional bandwidth used for FEC. To address this issue, we propose R-FEC which is a reinforcement learning (RL) based framework for video and FEC bitrate decisions in video conferencing. R-FEC aims to improve overall QoE by automatically learning through the results of past decisions and adjusting video and FEC bitrates to maximize the user QoE while minimizing the congestion in the network. Our experiments show that R-FEC outperforms the state-of-the-art solutions in video conferencing, with up to 27% improvement in its video rate and 6dB PSNR improvement in video quality over the default WebRTC.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":103,"string":"103"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":52,"string":"52"}}},{"rowIdx":53,"cells":{"question_id":{"kind":"string","value":"Arijit Raychowdhury"},"question":{"kind":"string","value":"Generate an abstract for the title \"Embedded hybrid LDO topologies for digital load circuits\" using the following items: digital regulators, low dropout voltage regulator, steady state accuracy, hybrid topology, 130 nm CMOS process."},"answer":{"kind":"string","value":"Digital low dropout voltage regulators provide digital process synthesizability, fast transient response and performance adaptation but lack steady state voltage regulation performance. To overcome this lack of steady state accuracy due to limit cycle oscillations, a hybrid low dropout voltage regulator topology designed in 130 nm CMOS process is presented. In the proposed topology, the operational discrete dynamics of a digital regulator are augmented with continuous dynamics of an analog regulator in a parallel controller configuration to achieve better steady state performance. It has been shown that a higher gain bandwidth product of the analog LDO achieves greater reduction of limit cycle oscillations but uneven controller strengths and power consumption limits its use for wide operational range of digital load circuits."},"correct_answer":{"kind":"string","value":"Digital low dropout voltage regulators provide digital process synthesizability, fast transient response and performance adaptation but lack steady state voltage regulation performance. To overcome this lack of steady state accuracy due to limit cycle oscillations, a hybrid low dropout voltage regulator topology designed in 130 nm CMOS process is presented. In the proposed topology, the operational discrete dynamics of a digital regulator are augmented with continuous dynamics of an analog regulator in a parallel controller configuration to achieve better steady state performance. It has been shown that a higher gain bandwidth product of the analog LDO achieves greater reduction of limit cycle oscillations but uneven controller strengths and power consumption limits its use for wide operational range of digital load circuits."},"documents":{"kind":"list like","value":["Title: A 1.05 V 1.6 mW, 0.45 <formula formulatype=\"inline\"> <tex Notation=\"TeX\">$^{\\circ}$</tex></formula>C 3<formula formulatype=\"inline\"> <tex Notation=\"TeX\">$\\sigma$</tex></formula> Resolution <formula formulatype=\"inline\"> <tex Notation=\"TeX\">$\\Sigma\\Delta$</tex></formula> Based Temperature Sensor With Parasitic Resistance Compensation in 32 nm Digital CMOS Process\nYear: 2009\n\nAbstract: Monitoring temperature in a microprocessor is important for optimal energy consumption under various workloads. This paper presents a temperature sensor in a 32 nm high-k metal gate digital CMOS process for integration in a microprocessor core. The sensor uses a ratio of currents driven into a BJT pair with current chopping to up-convert the temperature signal. A second order sigma-delta (ΣΔ) 1-bi...","Title: Neuro Inspired Computing with Coupled Relaxation Oscillators\nYear: 2014\n\nAbstract: Harnessing the computational capabilities of dynamical systems has attracted the attention of scientists and engineers form varied technical disciplines over decades. The time evolution of coupled, non-linear synchronous oscillatory systems has led to active research in understanding their dynamical properties and exploring their applications in brain-inspired, neuromorphic computational models. In this paper we present the realization of coupled and scalable relaxation-oscillators utilizing the metal-insulator-metal transition of vanadium-dioxide (VO2) thin films. We demonstrate the potential use of such a system in pattern recognition, as one possible computational model using such a system.","Title: Analysis of super cut-off transistors for ultralow power digital logic circuits\nYear: 2006\n\nAbstract: Super cut-off devices with sub-60mV/decade subthreshold swings have recently been demonstrated and being extensively studied. This paper presents a feasibility analysis of such tunneling devices for ultralow power subthreshold logic. Analysis shows that this device can deliver 800X higher performance (@iso-IOFF) compared to a MOSFET. The possible use of this device as a sleep transistor in conjunction with the regular Si MOSFET shows 2000X average improvement in leakage power compared to Si MOSFETs.","Title: A high density, carbon nanotube capacitor for decoupling applications\nYear: 2006\n\nAbstract: We present a novel application for carbon nanotube devices, implementing a high density 3-D capacitor, which can be useful for decoupling applications to reduce supply voltage variations. The capacitor consists of staggered layers of interleaved carbon nanotubes, alternately connected to anode and cathode contacts. The device can realize a capacitance/area, significantly larger than the ITRS's projected requirements for year 2018. The capacitance per unit area can exceed 1pF/μm2, with a quality factor greater than 100 at 1GHz.","Title: TapeCache: a high density, energy efficient cache based on domain wall memory\nYear: 2012\n\nAbstract: Domain Wall Memory (DWM) is a recently developed spin-based memory technology in which several bits of data are densely packed into the domains of a ferromagnetic wire. DWM has shown great promise in enabling non-volatile memory with unprecedented density and high energy efficiency. In this work, we propose TapeCache, a first attempt to employ DWMs as last-level caches in general purpose computing platforms. DWMs enable much higher density compared to SRAM, DRAM, and other spin-based memory technologies such as STT-MRAM. However, they also pose unique challenges such as serial access to the bits stored in a DWM cell, leading to variable access latencies. We propose a novel circuit-architecture co-design for TapeCache, consisting of (i) a multi-port DWM macro-cell optimized for read operations considering the asymmetry in applications' read/write characteristics, and (ii) a new cache organization and suitable management policies that mitigate the performance penalty arising from serial access to bits in a macro-cell. Over a wide range of SPEC 2006 benchmarks, TapeCache achieves 7.8X improvement in area, an average energy improvement of 7.3X, and an average performance improvement of 1.2% compared to an iso-capacity SRAM cache. Compared to an iso-capacity STT-MRAM cache, TapeCache obtains 2.3X improvement in area and 1.4X average energy savings with virtually identical performance.","Title: Computing with subthreshold leakage: device/circuit/architecture co-design for ultralow-power subthreshold operation\nYear: 2005\n\nAbstract: This paper presents a novel design methodology for ultralow-power design using subthreshold leakage as the operating current (suitable for medium frequency of operation: tens to hundreds of millihertz). Standard design techniques suitable for super-threshold design can be used in the subthreshold region. However, in this study, it has been shown that a complete co-design at all levels of hierarchy (device, circuit, and architecture) is necessary to reduce the overall power consumption while achieving acceptable performance (hundreds of millihertz) in the subthreshold regime of operation. Simulation results of co-design on a five-tap finite-impulse-response filter shows ∼2.5 × improvement in throughput at iso-power compared to a conventional design.","Title: Modeling of Ballistic Carbon Nanotube Field Effect Transistors for Efficient Circuit Simulation\nYear: 2003\n\nAbstract: Carbon Nanotube Field-Effect Transistors (CNFETs) arebeing extensively studied as possible successors to CMOS.Novel device structures have been fabricated and devicesimulators have been developed to estimate theirperformance in a sub 10nm transistor era. This paperpresents a novel method of circuit-compatible modeling ofCNFETs in their ultimate performance limit. The model sodeveloped has been used to simulate arithmetic and logicblocks using HSPICE.","Title: Modeling and analysis of system stability in a distributed power delivery network with embedded digital linear regulators.\nYear: 2014\n\nAbstract: On-chip power delivery networks (PDNs) for today's microprocessors and systems-on-chip (SoCs), which are characterized by dynamic supply voltage, many embedded integrated VRs (IVRs), lower decoupling-capacitor, high current ranges, multiple power modes and fast transient loads are designed to minimize AC load transients and supply noise. The close interaction of the VRs with the power grids create multiple feedback paths in the overall network, compromising the resultant phase margin and can even lead to system instabilities. The introduction of digital linear regulators operating in the low dropout (LDO) mode, with low power supply rejection, further exacerbates the problem. This paper provides a comprehensive methodology, based on Mason's Gain Formula applied to hybrid control, for modeling and analyzing distributed linear regulators and their interaction with the PDN.","Title: Modeling and analysis of digital linear dropout regulators with adaptive control for high efficiency under wide dynamic range digital loads\nYear: 2014\n\nAbstract: Discrete time digital linear regulators, including low dropout regulators (LDOs) have become competitive in muti-Vcc digital systems for fine-grained spatio-temporal voltage regulation and distribution. However, wide dynamic current range of the digital load circuits poses serious problems in maintaining stability and high efficiency at all corners. In this paper we present a control model for discrete time LDOs and demonstrate how online adaptive control can be employed for consistent performance and high efficiency across the load current range.","Title: Accurate estimation of total leakage current in scaled CMOS logic circuits based on compact current modeling\nYear: 2003\n\nAbstract: Dramatic increase of subthreshold, gate and reverse biased junction band-to-band-tunneling (BTBT) leakage in scaled devices, results in the drastic increase of total leakage power in a logic circuit. In this paper a methodology for accurate estimation of the total leakage in a logic circuit based on the compact modeling of the different leakage current in scaled devices has been developed. Current models have been developed based on the exact device geometry, 2-D doping profile and operating temperature. A circuit level model of junction BTBT leakage (which is unprecedented) has been developed. Simple models of the subthreshold current and the gate current have been presented. Here, for the first time, the impact of quantum mechanical behavior of substrate electrons, on the circuit leakage has been analyzed. Using the compact current model, a transistor has been modeled as a Sum of Current Sources (SCS). The SCS transistor model has been used to estimate the total leakage in simple logic gates and complex logic circuits (designed with transistors of 25nm effective length) at the room and at the elevated temperatures.","Title: A Feasibility Study of Subthreshold SRAM Across Technology Generations\nYear: 2005\n\nAbstract: Abstract: In this paper we have explored the feasibility of designing an SRAM array in the subthreshold domain of device operation. We have performed a nominal corner analysis of power and stability and a statistical analysis of the different failure probablilities of the subthreshold SRAM. Our analysis shows that subthreshold SRAM gives significant reduction (~100X) of operating amd standby power at iso-performance (~100MHz) compared to the superthreshold counterpart. However, with increasing intra-die variation owing to technology scaling, the failure probability of subthreshold SRAM increases thereby masking the power benefits.","Title: Delay Fault Localization in Test-Per-Scan BIST Using Built-In Delay Sensor\nYear: 2006\n\nAbstract: Delay failures are becoming a dominant failure mechanism in nanometer technologies. Diagnosis of such failures is important to ensure yield and robustness of the design. However, the increasing circuit size limits the granularity of diagnosis, resulting in large suspect fault list. In this paper, we present a methodology for improving delay fault localization in test-per-scan BIST using on-die delay sensing at selective test points. It is demonstrated that the proposed technique can improve the resolution of fault localization for both transition and segment delay fault models. Experimental results for a set of ISCAS89 benchmarks show upto 49% (82%) average improvement in fault localization for transition (segment) delay fault models. The area overhead due to delay sensing hardware have been limited to 4%.","Title: Design for test and reliability in ultimate CMOS\nYear: 2012\n\nAbstract: This session brings together specialists from the DfT, DfY and DfR domains that will address key problems together with their solutions for the 14nm node and beyond, dealing with extremely complex chips affected by high defect levels, unpredictable and heterogeneous timing behavior, circuit degradation over time, including extreme situations related with the ultimate CMOS nodes, where all processor nodes, routers and links of single-chip massively parallel tera-device processors could comprise timing faults (such as delay faults or clock skews); a large percentage of these parts are affected by catastrophic failures; all parts experience significant performance degradations over time; and new catastrophic failures occur at low MTBF.","Title: All-Digital Circuit-Level Dynamic Variation Monitor for Silicon Debug and Adaptive Clock Control.\nYear: 2011\n\nAbstract: A 45 nm microprocessor integrates an all-digital dynamic variation monitor (DVM) to continuously measure the impact of dynamic parameter variations on circuit-level performance to enhance silicon debug and adaptive clock control. The DVM consists of a tunable replica circuit, a time-to-digital converter, and multiplexers to measure circuit delay or frequency changes with less than a 1% measured re...","Title: Device optimization for ultra-low power digital sub-threshold operation\nYear: 2004\n\nAbstract: Digital circuits operated in the sub-threshold region (supply voltage less than the transistor threshold voltage) can have orders of magnitude power advantage over standard CMOS circuits for applications requiring ultra-low power and medium frequency of operation. It is possible to implement sub-threshold logic circuits using the standard transistors that are designed primarily for ultra high performance super-threshold logic design. However, a Si MOSFET so optimized for performance in the super-threshold regime is not the best device to use in the sub-threshold domain. In this paper, we propose device designs apt for sub-threshold operation. Results show that the optimized device improves the delay and power delay product (PDP) of an inverter chain by 44% and 51%, respectively, over the normal super-threshold device operated in the sub-threshold region.","Title: Leakage Power Analysis and Reduction for Nanoscale Circuits\nYear: 2006\n\nAbstract: Leakage current in the nanometer regime has become a significant portion of power dissipation in CMOS circuits as threshold voltage, channel length, and gate oxide thickness scale downward. Various techniques are available to reduce leakage power in high-performance systems.","Title: Carbon Nanotube Electronics: Design of High-Performance and Low-Power Digital Circuits\nYear: 2007\n\nAbstract: Scaling of silicon transistors continue in the sub 100-nm regime amidst severe roadblocks. Increased short-channel effects, rising leakage currents, severe process parameter variations are only a few of the overwhelming challenges that the device and circuit designers are faced with. In an attempt to alleviate the problems associated with the scaling of silicon transistors, researchers have began ...","Title: A circuit model for carbon nanotube interconnects: comparative study with Cu interconnects for scaled technologies\nYear: 2004\n\nAbstract: Semiconducting carbon nanotubes (CNT) have gained immense popularity as possible successors to silicon as the channel material for ultra high performance field effect transistors. On the other hand, their metallic counterparts have often been regarded as ideal interconnects for the future technology generations. Owing to their high current densities and increased reliability, metallic-single walled CNTs (SWCNTs) have been subjects of fundamental research both in theory as well as experiments. Metallic CNTs have been modeled for RF applications in (Burke, 2003) using an LC model. We present an efficient circuit compatible RLC model for metallic SW CNTs, and analyze the impact of SW CNTs on the performance of ultra scaled digital VLSI design.","Title: A Novel Low-overhead Delay Testing Technique for Arbitrary Two-Pattern Test Application\nYear: 2005\n\nAbstract: With increasing process fluctuations in nano-scale technology, testing for delay faults is becoming essential in manufacturing test to complement stuck-at-fault testing. Design-for-testability techniques,such as enhanced scan are typically associated with considerable overhead in die-area,circuit performance, and power during normal mode of operation. This paper presents a novel test technique, which can be used as an alternative to the enhanced scan based delay fault testing method, with significantly less design overhead. Instead of using an extra latch as in the enhanced scan method, we propose using supply gating at the first level of logic gates to hold the state of a combinational circuit. Experimental results on a set of ISCAS89 benchmarks show an average reduction of 33% in area overhead with an average improvement of 71% in delay overhead and 90% in power overhead during normal mode of operation, compared to the enhanced scan implementation.","Title: Effectiveness Of Energy Recovery Techniques In Reducing On-Chip Power Density In Molecular Nano-Technologies\nYear: 2004\n\nAbstract: As scaling of silicon devices continues at an aggressive pace, the problems associated with it are becoming more and more evident. With 'short channel effects' already in the way of scaling, interest has shifted to the possible use of non-silicon molecular devices for circuit implementation. Carbon nanotube has emerged as a promising candidate. However, molecular devices such as Carbon Nanotube FETs (CNFETs) with their super-scaled dimensions and high current densities would increase the power density on chip and reasonable predictions estimate that they would far exceed the maximum power density limitation [2]. This paper explores the use of energy-recovery techniques in molecular CNFET based digital circuits and demonstrates how they can solve the power density problem in such circuits.","Title: A 45 nm Resilient Microprocessor Core for Dynamic Variation Tolerance\nYear: 2011\n\nAbstract: A 45 nm microprocessor core integrates resilient error-detection and recovery circuits to mitigate the clock frequency (FCLK) guardbands for dynamic parameter variations to improve throughput and energy efficiency. The core supports two distinct error-detection designs, allowing a direct comparison of the relative trade-offs. The first design embeds error-detection sequential (EDS) circuits in critical paths to detect late timing transitions. In addition to reducing the Fclk guardbands for dynamic variations, the embedded EDS design can exploit path-activation rates to operate the microprocessor faster than infrequently-activated critical paths. The second error-detection design offers a less-intrusive approach for dynamic timing-error detection by placing a tunable replica circuit (TRC) per pipeline stage to monitor worst-case delays. Although the TRCs require a delay guardband to ensure the TRC delay is always slower than critical-path delays, the TRC design captures most of the benefits from the embedded EDS design with less implementation overhead. Furthermore, while core min-delay constraints limit the potential benefits of the embedded EDS design, a salient advantage of the TRC design is the ability to detect a wider range of dynamic delay variation, as demonstrated through low supply voltage (VCC) measurements. Both error-detection designs interface with error-recovery techniques, enabling the detection and correction of timing errors from fast-changing variations such as high-frequency VCC droops. The microprocessor core also supports two separate error-recovery techniques to guarantee correct execution even if dynamic variations persist. The first technique requires clock control to replay errant instructions at 1/2FCLK. In comparison, the second technique is a new multiple-issue instruction replay design that corrects errant instructions with a lower performance penalty and without requiring clock control. Silico- - n measurements demonstrate that resilient circuits enable a 41% throughput gain at equal energy or a 22% energy reduction at equal throughput, as compared to a conventional design when executing a benchmark program with a 10% VCC droop. In addition, the microprocessor includes a new adaptive clock control circuit that interfaces with the resilient circuits and a phase-locked loop (PLL) to track recovery cycles and adapt to persistent errors by dynamically changing Fclk f°Γ maximum efficiency.","Title: Leakage Current Based Stabilization Scheme for Robust Sense-Amplifier Design for Yield Enhancement in Nano-scale SRAM\nYear: 2005\n\nAbstract: In this paper, we develop a method to analyze the probability of access failure in SRAM array (due to random Vt variation in transistors) by jointly considering variations in cell and senseamplifiers. Our analysis shows that, improving robustness of senseamplifier is extremely important for reducing memory access failure probability and improving yield. We present a process variation tolerant sense amplifier suitable for SRAM array designed in sub- 100nm CMOS technologies. The proposed technique reduces the failure probability of sense amplifiers by more than 80% with negligible penalty in the sensing delay.","Title: Error Detection and Correction in Microprocessor Core and Memory Due to Fast Dynamic Voltage Droops\nYear: 2011\n\nAbstract: Built-in resiliency features enable a microprocessor to detect and correct errors due to fast dynamic voltage droop events as well as other types of dynamic variations. Timing errors in the microprocessor core as well as read (RD) and write (WR) errors in the 8T SRAM based cache can be detected. As a result, guardbands added for these variations are reduced or eliminated, improving performance and reducing power consumption. Measurements on a 45 nm research microprocessor core demonstrate 41% improvement in throughput or 22% reduction in energy at 0.8 V. Measurements on the cache demonstrate reduction of the minimum operating Vcc (VMIN) by 9% thereby resulting in a 7.5% reduction of net operating power.","Title: Arbitrary Two-Pattern Delay Testing Using a Low-Overhead Supply Gating Technique\nYear: 2008\n\nAbstract: With increasing defect density and process variations in nanometer technologies, testing for delay faults is becoming essential in manufacturing test to complement stuck-at-fault testing. This paper presents a novel test technique based on supply gating, which can be used as an alternative to the enhanced scan based delay fault testing, with significantly less design overhead. Experimental results on a set of ISCAS89 benchmarks show an average reduction of 34% in area overhead with an average improvement of 65% in delay overhead and 90% in power overhead during normal mode of operation, compared to the enhanced scan implementation.","Title: Frequency Specification Testing of Analog Filters Using Wavelet Transform of Dynamic Supply Current\nYear: 2004\n\nAbstract: The wavelet transform has the property of resolving the signal in both time and frequency, unlike the Fourier transform. In this work, we show that time-domain information obtained from wavelet analysis of the supply current can be used to efficiently test the frequency specification of analog filters. The pole/zero locations in the frequency response of analog filters shift due to changes in component values with process variations. It is essential to test the filters for the shift in frequency response and fix it, during production test. Wavelet analysis of the supply current can be a promising alternative to test the frequency specification of analog filters, since it needs only one ac stimulus and is virtually unaffected by transistor threshold variation. Simulation results on two test circuits demonstrate that we can estimate the pole/zero shift with less than 3% error using only one measurement, which requires about 18 measurements in the conventional technique.","Title: Beyond charge based computation: Design space exploration of spin transfer torque based MRAMs for embedded applications.\nYear: 2013\n\nAbstract: Ever larger on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1–3]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin torque transfer (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The minimum size cell (mincell) contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3Fx2F=6F2. In this paper, we examine the design space for key magnetic material properties and access transistor needed for embedded on-die memory with adequate scalability, density, read/write performance and robustness against various intrinsic variabilities and disturbances. New models and simulation methodologies, calibrated to existing measurements [1], for read, write and disturbance mechanisms are developed. Different storage node structures and materials are evaluated to reveal the mos- promising scaling options.","Title: Defect Oriented Testing of Analog Circuits Using Wavelet Analysis of Dynamic Supply Current\nYear: 2005\n\nAbstract: In recent years, Defect Oriented Testing (DOT) has been investigated as an alternative testing method for analog circuits. In this paper, we propose a wavelet transform based dynamic supply current (IDD) analysis technique for detecting catastrophic and parametric faults in analog circuits. Wavelet transform has the property of resolving events in both time and frequency domain simultaneously unlike Fourier transform which decomposes a signal in frequency components only. Simulation results on benchmark circuits show that wavelet transform has higher fault detection sensitivity than Fourier or time-domain methods and hence, can be considered very promising for defect oriented testing of analog circuits. Effectiveness of wavelet transform based DOT amidst process variation and measurement noise is studied.","Title: A Novel Delay Fault Testing Methodology Using Low-Overhead Built-In Delay Sensor\nYear: 2006\n\nAbstract: A novel integrated approach for delay-fault testing in external (automatic-test-equipment-based) and test-per-scan built-in self-test (BIST) using on-die delay sensing and test point insertion is proposed. A robust, low-overhead, and process-tolerant on-chip delay-sensing circuit is designed for this purpose. An algorithm is also developed to judiciously insert delay-sensor circuits at the internal nodes of logic blocks for improving delay-fault coverage with little or no impact on the critical-path delay. The proposed delay-fault testing approach is verified for transition- and segment-delay-fault models. Experimental results for external testing (BIST) show up to 31% (30%) improvement in fault coverage and up to 67.5% (85.5%) reduction in test length for transition faults. An increase in the number of robustly detectable critical-path segments of up to 54% and a reduction in test length for the segment-delay-fault model of up to 76% were also observed. The delay and area overhead due to insertion of the delay-sensing hardware have been limited to 2% and 4%, respectively","Title: PETE: A device/circuit analysis framework for evaluation and comparison of charge based emerging devices\nYear: 2009\n\nAbstract: This paper describes PETE, a tool that has been developed for circuit/system level evaluation of nanoscaled devices. The motivation behind developing this tool is the fact that traditional device metrics like CV/Ion, Ioff or CV2f can no longer capture the true potential of semiconductor devices and underestimate or overestimate system level performance. At the same time, the development and deployment of compact models for any new device is a time-consuming effort, a task that can only be undertaken once the potential of the de established. Towards this end, we have developed PETE, so that device and circuit designers can perform a fast and reasonably accurate estimation of any new device without having to develop compact models. The inputs to PETE can be numerical I-V and C-V characteristics (derived from experiments or device simulations), and the tool can numerically evaluate a wide array of circuit/system level metrics pertaining to performance and power of logic gates, ring oscillators and mega-cells. We have evaluated four emerging device technologies, namely, 15 nm Silicon MOSFET transistors, Multi transistors, Band-to-band-tunneling transistors, and Ferroelectric FETs with PETE and the results obtained are within a 5% level of inaccuracy when compared to a traditional SPICE based approach. PETE has been deployed on the nanoHUB (nanohub.org) for public use, and its simple web interface ensures that even a non-expert in circuits can obtain accurate estimation of performance-power trade new technology.","Title: Optimization of burn-in test for many-core processors through adaptive spatiotemporal power migration\nYear: 2010\n\nAbstract: We present adaptive spatiotemporal power migration (ASTPM) for burn-in of many core chips. ASTPM adapts the number of simultaneously stressed cores and dynamically varies their location to prevent thermal runaway, improve test-quality, and optimize burn-in time.","Title: Resilient microprocessor design for high performance & energy efficiency\nYear: 2010\n\nAbstract: Conventional microprocessors require a clock frequency (FCLK) guardband to ensure correct functionality during infrequent dynamic operating variations in supply voltage (VCC), temperature, and transistor aging. Consequently, these inflexible designs cannot exploit opportunities for higher performance by increasing FCLK or lower energy by reducing VCC during favorable operating conditions. This presentation describes a 45nm resilient microprocessor with error-detection and recovery circuits to detect and correct timing errors from dynamic variations to mitigate the FCLK guardband, thus enabling higher performance or lower energy as compared to a conventional design. The microprocessor core supports two distinct error-detection designs and two separate error-recovery techniques, allowing a direct comparison of the relative trade-offs. Silicon measurements demonstrate that resilient circuits enable a 41% throughput gain at equal energy or a 22% energy reduction at equal throughput, as compared to a conventional design when executing a benchmark program with a 10% VCC droop. In addition, the resilient circuits guide an adaptive clock controller that tracks recovery cycles and adapts to persistent variations by changing FCLK. The combination of error-detection and recovery circuits with dynamic adaptation allows the microprocessor to adapt to the operating environment to deliver maximum efficiency. The presentation concludes by discussing the opportunity of applying resilient techniques to enhance the dynamic operating range (i.e., high-performance and low-power modes) for microprocessors.","Title: Novel Low-Overhead Operand Isolation Techniques For Low-Power Datapath Synthesis\nYear: 2006\n\nAbstract: Power consumption in datapath modules due to redundant switching is an important design concern for high-performance applications. Operand isolation schemes are adopted to reduce redundant switching in datapaths. However, they incur considerable overhead in terms of delay, power, and area. This paper presents novel operand isolation techniques based on supply gating that reduce the overheads associated with isolating circuitry. The proposed schemes also target leakage minimization and application of operand isolation at the internal logic of datapath to further reduce power consumption. We integrate the proposed techniques and power/delay models to develop a complete flow for low-power datapath synthesis. Simulation results show that the proposed operand isolation techniques can achieve at least 40% reduction in power consumption compared to the original circuit with minimal area overhead (5%) and small delay penalty (0.15%).","Title: Tunable Replica Bits for Dynamic Variation Tolerance in 8T SRAM Arrays\nYear: 2011\n\nAbstract: Infrequent dynamic events like VCC droops and temperature changes result in the use of a static VCC guardband in 8T SRAM arrays. This paper proposes the use of tunable replica bits (TRBs) as a potential solution to mitigating a part of the VCC guardband. Measured data on a 16 KB 8T array featuring tun able replica bits illustrate 9% reduction of the operating minimum VCC (VMIN) and correspondingly a 7.5% reduction in array power.","Title: A Model Study of an All-Digital, Discrete-Time and Embedded Linear Regulator.\nYear: 2015\n\nAbstract: With an increasing number of power-states, finer- grained power management and larger dynamic ranges of digital circuits, the integration of compact, scalable linear-regulators embedded deep within logic blocks has become important. While analog linear-regulators have traditionally been used in digital ICs, the need for digitally implementable designs that can be synthesized and embedded in digital functional units for ultra fine- grained power management has emerged. This paper presents the circuit design and control models of an all-digital, discrete-time linear regulator and explores the parametric design space for transient response time and loop stability.","Title: The role of adaptation and resiliency in computation and power management\nYear: 2014\n\nAbstract: Variations, both static and dynamic in nature, impact the performance and power-efficiency of microprocessors and other digital integrated circuits. While static process variations can often be mitigated through binning or by post-silicon tuning, dynamic variations change as a function of time and environment and cannot be reduced by static tuning. Examples of these types of dynamic variations include power supply (VCC) droop, temperature change, and device aging over time. The droop magnitude, frequency and duration depend on the complex interaction of capacitive and inductive parasitics at the board, package, and die levels and change with the workload and current demand [1-3]. VCC droops contain high-frequency (i.e., fast changing) and low-frequency (i.e., slow changing) components and occur locally and/or globally across the die. Temperature variations occur at a relatively slower time scale with local hot spots on the die, depending on environmental and workload conditions as well as the heat-removal capability of the package. Further, transistor aging slowly degrades the drive current over time as a function of gate bias and temperature conditions. Conventional designs build in VCC guardband (VCC GB) at a target frequency to ensure correct functionality even in the presence of worst-case dynamic variations. In the digital core, this GB accounts for the delay increase on critical paths when dynamic variations occur and guarantees that timing constraints are met even under worst-case conditions. In the storage arrays (register files and caches) this GB is added to the static minimum operating voltage (VMIN) to obtain the resultant operating VMIN and results in an increase of both leakage and dynamic array power. The key design aspect of adaptive and resilient designs is to remove a part of this GB, such that logic timing and memory functionality can be met at a lower VCC. This improves energy efficiency and improves battery life; a key consideration in mobile and handheld platforms. The mitigation of the design GB can be achieved in two fundamentally different ways. For dynamic variations with time scales in the order of hundreds of μs to ms (such as temperature variations or transistor aging), a reactive scheme where any functional error is avoided is applicable. For example, embedded temperature sensors can be used to trigger changes in the clock frequency or changes in the supply voltage, such that at low temperatures (when transistor currents are higher) a faster clock (at iso-VCC) or a lower supply (at iso-clock frequency) can be employed [4]. For dynamic changes which occur in time scales of ns to μs, such reactive schemes are impossible by design. Hence, an alternative scheme can be employed where timing errors (in logic) or read-write errors (in memory) are allowed to happen. Once errors occur, they are detected, and the errant instruction is replayed with proper care such that data integrity is maintained. A combination of such adaptive schemes (Fig. 1) result in the mitigation of a major part of the design GB, resulting in higher energy efficiency.","Title: 5.6 A 0.13μm fully digital low-dropout regulator with adaptive control and reduced dynamic stability for ultra-wide dynamic range\nYear: 2015\n\nAbstract: This paper presents a discrete-time, fully digital, scan-programmable LDO macro in 0.13μm technology featuring greater than 90% current efficiency across a 50× current range, and 8× improvement in transient response time in response to large load steps. The baseline design features a 128b barrel shifter that digitally controls 128 identical power PMOS devices to provide load and line regulation at the node VREG, for a scan-programmable fine-grained synthetic load. A clocked comparator, which eliminates the need for any bias current, controls the direction of shift, D. The programmable mux-select signals, MUX1 and MUX2, provide controllable closed loop gains, KBARREL, of 1 to 3×. Since at any clock edge only 1, 2 or 3 shifts can occur (depending on the gain setting), fine-grained clock gating is enabled by dividing the 128b shifter into four sections and only enabling the clock to the section(s) where the shift occurs.","Title: A 32 nm Embedded, Fully-Digital, Phase-Locked Low Dropout Regulator for Fine Grained Power Management in Digital Circuits\nYear: 2014\n\nAbstract: The need for fine-grained power management in digital ICs has led to the design and implementation of compact, scalable low-drop out regulators (LDOs) embedded deep within logic blocks. While analog LDOs have traditionally been used in digital ICs, the need for digitally implementable LDOs embedded in digital functional units for ultrafine grained power management is paramount. This paper presents a fully-digital, phase locked LDO implemented in 32 nm CMOS. The control model of the proposed design has been provided and limits of stability have been shown. Measurement results with a resistive load as well as a digital load exhibit peak current efficiency of 98%.","Title: Trim bit setting of analog filters using wavelet-based supply current analysis\nYear: 2004\n\nAbstract: Wavelet transform has the property of resolving signal in both time and frequency unlike Fourier transform. In this work, we show that time-domain information obtained from wavelet analysis of supply current can be used to efficiently trim analog filters. The pole/zero locations in the frequency response of analog filters shift due to change in component values with process variations. Wavelet analysis of supply current can be a promising alternative to test frequency specification of analog filters, since it needs only one test stimulus and is virtually unaffected by transistor threshold variation. Simulation results on two test circuits demonstrate that we can estimate pole/zero shift with less than 3% error.","Title: Spin torque devices in embedded memory: Model studies and design space exploration\nYear: 2013\n\nAbstract: Ever larger on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1-3]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin torque transfer (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The minimum size cell (mincell) contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3Fx2F=6F2. In this paper, we examine the design space for key magnetic material properties and access transistor needed for embedded on-die memory with adequate scalability, density, read/write performance and robustness against various intrinsic variabilities and disturbances. New models and simulation methodologies, calibrated to existing measurements [1], for read, write and disturbance mechanisms are developed. Different storage node structures and materials are evaluated to reveal the most promising scaling options.","Title: Exploiting Synchronization Properties of Correlated Electron Devices in a Non-Boolean Computing Fabric for Template Matching\nYear: 2014\n\nAbstract: As complementary metal-oxide-semiconductor (CMOS) scaling continues to offer insurmountable challenges, questions about the performance capabilities of Boolean, digital machine based on Von-Neumann architecture, when operated within a power budget, have also surfaced. Research has started in earnest to identify alternative computing paradigms that provide orders of magnitude improvement in power-performance for specific tasks such as graph traversal, image recognition, template matching, and so on. Further, post-CMOS device technologies have emerged that realize computing elements which are neither CMOS replacements nor suited to work as a binary switch. In this paper, we present the realization of coupled and scalable relaxation-oscillators utilizing the metal-insulator-metal transition of vanadium-dioxide (VO2) thin films. We demonstrate the potential use of such a system in a non-Boolean computing paradigm and demonstrate pattern recognition, as one possible application using such a system.","Title: Pulsed READ in spin transfer torque (STT) memory bitcell for lower READ disturb\nYear: 2013\n\nAbstract: Large on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1-2]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin transfer torque (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The smallest bitcell contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3F×2F=6F2 (Fig. 2).","Title: An Ultra-low power, “Always-On” Camera Front-End for Posture Detection in Body Worn Cameras using Restricted Boltzman Machines\nYear: 2015\n\nAbstract: The Internet of Things (IoTs) has triggered rapid advances in sensors, surveillance devices, wearables and body area networks with advanced Human-Computer Interfaces (HCI). One such application area is the adoption of Body Worn Cameras (BWCs) by law enforcement officials. The need to be ‘always-on’ puts heavy constraints on battery usage in these camera front-ends, thus limiting their widespread adoption. Further, the increasing number of such cameras is expected to create a data deluge, which requires large processing, transmission and storage capabilities. Instead of continuously capturing and streaming or storing videos, it is prudent to provide “smartness” to the camera front-end. This requires hardware assisted image recognition and template matching in the front-end, capable of making judicious decisions on when to trigger video capture or streaming. Restricted Boltzmann Machines (RBMs) based neural networks have been shown to provide high accuracy for image recognition and are well suited for low power and re-configurable systems. In this paper we propose an RBM based “always-on’’ camera front-end capable of detecting human posture. Aggressive behavior of the human being in the field of view will be used as a wake-up signal for further data collection and classification. The proposed system has been implemented on a Xilinx Virtex 7 XC7VX485T platform. A minimum dynamic power of 19.18 mW for a target recognition accuracy while maintaining real time constraints has been measured. The hardware-software co-design illustrates the trade-offs in the design with respect to accuracy, resource utilization, processing time and power. The results demonstrate the possibility of a true “always-on” body-worn camera system in the IoT environment.","Title: The Changing Computing Paradigm With Internet of Things: A Tutorial Introduction.\nYear: 2016\n\nAbstract: This Tutorial paper is about the Internet of Things, its applications, challenges, and how it may change the way of computing. Besides a comprehensive introduction, it focuses on two major design constraints, namely, security and power management.","Title: Modeling and Simulation of Vanadium Dioxide Relaxation Oscillators\nYear: 2015\n\nAbstract: This paper deals with modeling and simulation of a new family of two-terminal devices fabricated with vanadium dioxide material. Such devices allow realization of very compact relaxation nano-oscillators that can be connected electronically to form arrays of coupled oscillators. Challenging applications of oscillator arrays include the realization of multiphase signal generators and massively para...","Title: Enabling New Computation Paradigms with HyperFET - An Emerging Device.\nYear: 2016\n\nAbstract: High power consumption has significantly increased the cooling cost in high-performance computation stations and limited the operation time in portable systems powered by batteries. Traditional power reduction mechanisms have limited traction in the post-Dennard Scaling landscape. Emerging research on new computation devices and associated architectures has shown three trends with the potential to...","Title: Cache Design with Domain Wall Memory.\nYear: 2016\n\nAbstract: Domain wall memory (DWM) is a recently developed spin-based memory technology in which several bits of data are densely packed into the domains of a ferromagnetic wire. DWM has shown great promise in enabling non-volatile memory with very high density and energy efficiency, and has been explored for secondary storage and off-chip memory. In this work, we explore the use of DWM within the on-chip c...","Title: Integrated power management in IoT devices under wide dynamic ranges of operation\nYear: 2015\n\nAbstract: By the year 2020 it is expected that corresponding to every human being there would be seven connected devices. These connected devices will usher in the Internet of Things (IoTs) and would percolate every aspect of human life, changing the human experience at a fundamental level. In order to power these devices novel strategies would have to be developed as these devices will not only have a dynamic load, due to multiple features, but also dynamic sources if opportunistic energy harvesting is used to supplement the rechargeable battery. For the power delivery network, figures of merit would be to comprehend both the ability to supply the worst case design as well as to maintain high efficiency across a wide dynamic range. To maintain high efficiency for a large range we will need adaptive components on the load side as well as at the energy source. In this work we will discuss the general IoT power delivery network (PDN), current research and the state of the art PDN components, novel designs and control for interface circuits and energy harvesters.","Title: A Model Study of Defects and Faults in Embedded Spin Transfer Torque (STT) MRAM Arrays.\nYear: 2015\n\nAbstract: There has been a significant interest in Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) as a candidate for emerging memory technology for last-level embedded caches in the recent years. High density (3-4x of SRAM), non-volatility, nano-second Read and Write speeds, and process and voltage compatibility with CMOS are the attractive properties of this technology. A few studies have expounded on the reliability in this technology but various fault manifestations have not been studied in detail in the past. This paper attempts to study the fault models in STT-MRAM under both parametric variations as well as electrical defects (opens and shorts). Sensitivity of Read, Write and Retention to material and lithographic process parameters has been studied. Also electrical defects viz. intra-cell and inter-cell opens and shorts have been considered and the corresponding fault models have been identified and classified.","Title: A Light-powered, Always-On, Smart Camera with Compressed Domain Gesture Detection.\nYear: 2016\n\nAbstract: In this paper we propose an energy-efficient camera-based gesture recognition system powered by light energy for \\\"always on\\\" applications. Low energy consumption is achieved by directly extracting gesture features from the compressed measurements, which are the block averages and the linear combinations of the image sensor's pixel values. The gestures are recognized using a nearest-neighbour (NN) classifier followed by Dynamic Time Warping (DTW). The system has been implemented on an Analog Devices Black Fin ULP vision processor and powered by PV cells whose output is regulated by TI's DC-DC buck converter with Maximum Power Point Tracking (MPPT). Measured data reveals that with only 400 compressed measurements (768x compression ratio) per frame, the system is able to recognize key wake-up gestures with greater than 80% accuracy and only 95mJ of energy per frame. Owing to its fully self-powered operation, the proposed system can find wide applications in \\\"always-on\\\" vision systems such as in surveillance, robotics and consumer electronics with touch-less operation.","Title: All-digital linear regulators with proactive and reactive gain-boosting for supply droop mitigation in digital load circuits\nYear: 2016\n\nAbstract: This paper explores microarchitecture controlled proactive gain boosting as a means of lowering the effects of supply voltage droop in digital circuits powered by embedded, all-digital linear regulators. A behavioral power supply rejection model for all-digital linear regulator is presented. The presented regulator shows enhanced power supply rejection under increased operating frequency. Test-chip measurements in a 130nm CMOS process reveal more than 2X (4X) reduction in voltage droop (settling time) over purely reactive gain boosting.","Title: Vertex Coloring Of Graphs Via Phase Dynamics Of Coupled Oscillatory Networks\nYear: 2016\n\nAbstract: While Boolean logic has been the backbone of digital information processing, there exist classes of computationally hard problems wherein this paradigm is fundamentally inefficient. Vertex coloring of graphs, belonging to the class of combinatorial optimization, represents one such problem. It is well studied for its applications in data sciences, life sciences, social sciences and technology, and hence, motivates alternate, more efficient non-Boolean pathways towards its solution. Here we demonstrate a coupled relaxation oscillator based dynamical system that exploits insulator-metal transition in Vanadium Dioxide (VO2) to efficiently solve vertex coloring of graphs. Pairwise coupled VO2 oscillator circuits have been analyzed before for basic computing operations, but using complex networks of VO2 oscillators, or any other oscillators, for more complex tasks have been challenging in theory as well as in experiments. The proposed VO2 oscillator network harnesses the natural analogue between optimization problems and energy minimization processes in highly parallel, interconnected dynamical systems to approximate optimal coloring of graphs. We further indicate a fundamental connection between spectral properties of linear dynamical systems and spectral algorithms for graph coloring. Our work not only elucidates a physics-based computing approach but also presents tantalizing opportunities for building customized analog co-processors for solving hard problems efficiently.","Title: Computing with Dynamical Systems Based on Insulator-Metal-Transition Oscillators.\nYear: 2016\n\nAbstract: In this paper, we review recent work on novel computing paradigms using coupled oscillatory dynamical systems. We explore systems of relaxation oscillators based on linear state transitioning devices, which switch between two discrete states with hysteresis. By harnessing the dynamics of complex, connected systems, we embrace the philosophy of \"let physics do the computing\" and demonstrate how complex phase and frequency dynamics of such systems can be controlled, programmed, and observed to solve computationally hard problems. Although our discussion in this paper is limited to insulator-to-metallic state transition devices, the general philosophy of such computing paradigms can be translated to other mediums including optical systems. We present the necessary mathematical treatments necessary to understand the time evolution of these systems and demonstrate through recent experimental results the potential of such computational primitives.","Title: Analysis of Defects and Variations in Embedded Spin Transfer Torque (STT) MRAM Arrays.\nYear: 2016\n\nAbstract: Spin transfer torque magnetic random access memory (STT-MRAM) is a competitive, future memory technology for last-level embedded caches. It exhibits ultra-high density (3-4X of SRAM), non-volatility, nano-second Read and Write speeds, and process and voltage compatibility with CMOS. As the design and fabrication process mature for the STT-MRAM, there is a need to study the various fault models tha...","Title: A 130nm hybrid low dropout regulator based on switched mode control for digital load circuits.\nYear: 2016\n\nAbstract: A hybrid (digital and analog) low dropout regulator (LDO) utilizing switched mode control is designed in 130 nm CMOS for fine grain power management, fast droop recovery and robust small signal regulation of multi-V-CC digital loads. The design provides an optimal trade-off of performance and accuracy by switching between a digital and an analog control loop. The hybrid topology achieves robust small signal regulation and fast recovery from large signal transients or power state transitions. Measurements from a 130nm test-chip show Near-Threshold Voltage (NTV) operation, fast transient response of 18 ns for a load step of 10.3mA and a peak current efficiency of 98.64%.","Title: UVFR: A Unified Voltage and Frequency Regulator with 500MHz/0.84V to 100KHz/0.27V operating range, 99.4% current efficiency and 27% supply guardband reduction.\nYear: 2016\n\nAbstract: A fully-digital, single-loop Unified Voltage and Frequency Regulator (UVFR) is designed in 130nm CMOS to provide the correct supply to digital loads to meet a timing criteria. Simultaneously a Tunable Replica Circuit (TRC) based local oscillator is generated from the regulated supply and clocks the load. Measurements show 0.84V to 0.27V range of operation, and 27% supply guardband reduction at iso-performance through adaptation and resiliency which are intrinsic to the control loop.","Title: A Sar Pipeline Adc Embedding Time Interleaved Dac Sharing For Ultra-Low Power Camera Front Ends\nYear: 2015\n\nAbstract: The growing need for ultra-low power cameras for sensors, surveillance and consumer applications has resulted in significant advances in compressed domain data acquisition from pixel arrays. In this journal we present a novel 64-input Successive Approximation (SAR) Pipeline analog-to-digital converter (ADC) suitable for compressed domain data acquisition in camera front-ends. The proposed architecture features a time interleaved capacitive digital-to-analog converter (DAC) shared between column parallel ADCs for area savings (2.28X); and a shared amplifier stage for power savings (60%), achieving 4X throughput as compared to traditional architectures. Simulations on a 130nm foundry process shows that the proposed SAR Pipeline ADC draws 31 mu W at 2 MS/s having a target Figure-of-Merit (FOM) of 87 fJ/conv. per step at Nyquist rate. The proposed compressive sensing front end achieves per patch energy per patch of 0.9 nJ.","Title: High efficiency power side-channel attack immunity using noise injection in attenuated signature domain\nYear: 2017\n\nAbstract: With the advancement of technology in the last few decades, leading to the widespread availability of miniaturized sensors and internet-connected things (IoT), security of electronic devices has become a top priority. Side-channel attack (SCA) is one of the prominent methods to break the security of an encryption system by exploiting the information leaked from the physical devices. Correlational power attack (CPA) is an efficient power side-channel attack technique, which analyses the correlation between the estimated and measured supply current traces to extract the secret key. The existing countermeasures to the power attacks are mainly based on reducing the SNR of the leaked data, or introducing large overhead using techniques like power balancing. This paper presents an attenuated signature AES (AS-AES), which resists SCA with minimal noise current overhead. AS-AES uses a shunt low-drop-out (LDO) regulator to suppress the AES current signature by 400x in the supply current traces. The shunt LDO has been fabricated and validated in 130 nm CMOS technology. System-level implementation of the AS-AES along with noise injection, shows that the system remains secure even after 50K encryptions, with 10× reduction in power overhead compared to that of noise addition alone.","Title: In Quest of the Next Information Processing Substrate: Extended Abstract: Invited.\nYear: 2017\n\nAbstract: Conventional CMOS scaling and the Moore's law have been the cornerstone of progress in computing hardware technology. However, with dimensional scaling expected to end soon, there is a pressing need to find the next information processing hardware that can continue to support the technology revolution. Will this hardware solution be an enhanced or an augmented version of MOSFET or a switch based on a radically new switching mechanism. Ultimately, do we require a complete deviation from the Boolean paradigm itself? In this invited paper, we will review some of the actively pursued future logic, merged logic-memory and related concepts. While it remains unclear which of these options will eventually make it into commercial products, we will argue- based on lessons learnt from the past two decades of transistor development- that sustained and systematic research with careful benchmarking from future workload and applications viewpoint remains the key to success in the quest for the new information processing hardware.","Title: Test challenges in embedded STT-MRAM arrays\nYear: 2017\n\nAbstract: Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) is an emerging memory technology which exhibits non-volatility, high density and nanosecond read and write times. These attributes of STT-MRAM make it suitable for last level embedded caches. However, the defects and corresponding fault models of STT-MRAM are not as extensively explored as in SRAM and therefore, there is a growing need for defect and fault analysis. Moreover, stochastic retention failure of STTM-RAM imposes a large burden in testing time. Conventional test schemes for retention of STT-MRAM need to be optimized for testing a large-size embedded STT-MRAM array. This work presents a review of the different defect and fault mechanisms as well as a BIST architecture and circuit to reduce testing time in characterization and manufacturing tests for retention. We address the effect of resistive and capacitive defects and identify retention test setup for measuring worst case retention.","Title: Digitally-assisted leakage current supply circuit for reducing the analog LDO minimum dropout voltage\nYear: 2017\n\nAbstract: A digitally-assisted leakage current supply (LCS) circuit reduces the maximum current demand for analog lowdropout (LDO) voltage regulators to lower the minimum dropout voltage (VDO,MIN), and consequently, enable a wider range of LDO operation for power savings in system-on-chip processor cores. From silicon measurements in a 130nm test chip, the LCS assisted hybrid LDO decreases VDO,MIN by 30-38%, resulting in core power reduction of 21-28% at equal clock frequencies within the wider LDO operating range.","Title: Self-Optimizing IoT Wireless Video Sensor Node With In-Situ Data Analytics and Context-Driven Energy-Aware Real-Time Adaptation.\nYear: 2017\n\nAbstract: It is well understood that data-acquisition by distributed sensors and subsequent transmission of all the acquired data to the cloud will produce a “data deluge” in next-generation wireless networks leading to immense network congestion, and data back-logs on the server which will prevent real-time processing and control. This motivates in situ data analytics in energy-constrained wireless sensor ...","Title: Stochastic IMT (insulator-metal-transition) neurons: An interplay of thermal and threshold noise at bifurcation.\nYear: 2017\n\nAbstract: Artificial neural networks can harness stochasticity in multiple ways to enable a vast class of computationally powerful models. Boltzmann machines and other stochastic neural networks have been shown to outperform their deterministic counterparts by allowing dynamical systems to escape local energy minima. Electronic implementation of such stochastic networks is currently limited to addition of algorithmic noise to digital machines which is inherently inefficient; albeit recent efforts to harness physical noise in devices for stochasticity have shown promise. To succeed in fabricating electronic neuromorphic networks we need experimental evidence of devices with measurable and controllable stochasticity which is complemented with the development of reliable statistical models of such observed stochasticity. Current research literature has sparse evidence of the former and a complete lack of the latter. This motivates the current article where we demonstrate a stochastic neuron using an insulator-metal-transition (IMT) device, based on electrically induced phase-transition, in series with a tunable resistance. We show that an IMT neuron has dynamics similar to a piecewise linear FitzHugh-Nagumo (FHN) neuron and incorporates all characteristics of a spiking neuron in the device phenomena. We experimentally demonstrate spontaneous stochastic spiking along with electrically controllable firing probabilities using Vanadium Dioxide (VO2) based IMT neurons which show a sigmoid-like transfer function. The stochastic spiking is explained by two noise sources - thermal noise and threshold fluctuations, which act as precursors of bifurcation. As such, the IMT neuron is modeled as an Ornstein-Uhlenbeck (OU) process with a fluctuating boundary resulting in transfer curves that closely match experiments. The moments of interspike intervals are calculated analytically by extending the first-passage-time (FPT) models for Ornstein-Uhlenbeck (OU) process to include a fluctuating boundary. We find that the coefficient of variation of interspike intervals depend on the relative proportion of thermal and threshold noise, where threshold noise is the dominant source in the current experimental demonstrations. As one of the first comprehensive studies of a stochastic neuron hardware and its statistical properties, this article would enable efficient implementation of a large class of neuro-mimetic networks and algorithms.","Title: Connecting spectral techniques for graph coloring and eigen properties of coupled dynamics: A pathway for solving combinatorial optimizations (Invited paper).\nYear: 2017\n\nAbstract: This paper reviews an analog circuit system of capacitively coupled relaxation oscillators whose time evolution can be used to solve the graph coloring problem. These oscillators consist of a series combination of an insulator-metal-transition (IMT) device and a resistance. Such circuits were also demonstrated experimentally using VO 2 (Vanadium Dioxide) as the phase transition material. The time evolution of circuit dynamics depend on eigenvectors of the adjacency matrix in the same way as is used by spectral algorithms for graph coloring. As such, a coupled network of such oscillators with piecewise linear dynamics have steady state phases which can be used to approximate the minimum vertex coloring of a graph.","Title: A 65nm 376nA 0.4V linear classifier using time-based matrix-multiplying ADC with non-linearity aware training\nYear: 2017\n\nAbstract: A 6-bit time-based folding matrix multiplication technique for support vector machine (SVM) classification is proposed. A voltage controlled oscillator (VCO) based analog-to-digital converter (ADC) performs in-situ matrix multiplications (MM) along with analog to digital conversion. It also offers a low supply voltage of operation (down to 0.4V) and an input range of 0.8V, drawing a total of 376nA of current. We propose a technique to extend the input range of the VCO based ADC using a folding technique. The classifier is trained considering the non-linearity of the VCO, which results in 5X lower power at iso-accuracy. An accuracy of 93% is achieved with adaboost at the digital back-end with linear SVM as the weak classifier.","Title: Modeling and Analysis of Magnetic Field Induced Coupling on Embedded STT-MRAM Arrays.\nYear: 2018\n\nAbstract: Spin transfer torque magnetic random access memory (STT-MRAM) is an emerging memory technology which exhibits nonvolatility, high density, high endurance, and nano-second read and write times. These characteristics make STT-MRAM suitable for last-level cache and other embedded applications. The STT-MRAM bit-cell consists of a magnetic tunnel junction (MTJ) which is composed of two ferromagnetic la...","Title: Switched-Mode-Control Based Hybrid LDO for Fine-Grain Power Management of Digital Load Circuits.\nYear: 2018\n\nAbstract: Switched-mode-control (SMC) is a control methodology that allows instantaneous switching between controllers to extend the dynamic range of feedback circuits. A hybrid low dropout voltage regulator utilizing SMC is designed in 130 nm CMOS for fine-grain power management, fast droop recovery, and accurate voltage regulation of digital load circuits. The design provides an optimal tradeoff between p...","Title: A 130 nm 165 nJ/frame Compressed-Domain Smashed-Filter-Based Mixed-Signal Classifier for \"In-Sensor\" Analytics in Smart Cameras.\nYear: 2018\n\nAbstract: To avoid data deluge at the back end, it is imperative that advanced sensor nodes perform “in-sensor” processing to extract relevant features from data. We propose a compressed-domain smashed-filter-based object recognition system and measurements from a 130 nm mixed-signal test chip to demonstrate reconfigurable and ultra-low power operation. We measure greater than 90% accuracy in object localiz...","Title: A 65nm compressive-sensing time-based ADC with embedded classification and INL-aware training for arrhythmia detection.\nYear: 2017\n\nAbstract: In-sensor analytics are in high demand to avoid high computation at server back end. Traditional analog sensors require high supply voltage in the range of 1–1.2V even when digital supplies are scaled down to 0.4V-0.6V. We propose a time-based compressed-domain analog-to-digital (ADC) based encoder with parallel processing units for arrhythmia classification. The computationally enhanced ADC performs in-situ compression along with analog to digital conversion. An accuracy of 84% accuracy is achieved with 10.5nJ energy per classification for an 8X compression ratio.","Title: Smart Sensing for HVAC Control: Collaborative Intelligence in Optical and IR Cameras.\nYear: 2018\n\nAbstract: Energy management of heating, ventilation, and cooling (HVAC) has become a primary concern for residential and commercial buildings. In order to save energy without compromising the comfort of occupants, various techniques have been explored to sense the real-time occupancy/vacancy of HVAC zones. Among all these approaches, wireless-camera-based sensing stands out for its potential application in ...","Title: NavREn-Rl: Learning to fly in real environment via end-to-end deep reinforcement learning using monocular images\nYear: 2018\n\nAbstract: We present NavREn-RL, an approach to NAVigate an unmanned aerial vehicle in an indoor Real ENvironment via end-to-end reinforcement learning (RL). A suitable reward function is designed keeping in mind the cost and weight constraints for micro drone with minimum number of sensing modalities. Collection of small number of expert data and knowledge based data aggregation is integrated into the RL process to aid convergence. Experimentation is carried out on a Parrot AR drone in different indoor arenas and the results are compared with other baseline technologies. We demonstrate how the drone successfully avoids obstacles and navigates across different arenas. Video of the drone navigating using the proposed approach can be seen at https://youtu.be/yOTkTHUPNVY.","Title: Computing with Coupled Oscillators: Theory, Devices, and Applications\nYear: 2018\n\nAbstract: This paper will give a review of recent work on using networks of coupled oscillators for analog information processing. We will discuss the rationale of using coupled oscillators, and how they can be used to perform computational tasks, such as associative computing primitives, or how they can serve as hardware accelerators in vision processing pipelines. Further, we will study two specific physical implementations for such oscillator, namely relaxation oscillators based on metal-insulator phase transitions and magnetic spin-torque oscillators. We will also discuss the potential of such coupled-oscillator networks to solve computationally-hard optimization problems or even NP-hard problems.","Title: A Light-Powered Smart Camera With Compressed Domain Gesture Detection.\nYear: 2018\n\nAbstract: This paper presents an ultralow power smart camera with gesture detection. Low power is achieved by directly extracting gesture features from the compressed measurements, which are the block averages and the linear combinations of the image sensor's pixel values. We present two classifier techniques to allow low computational and storage requirements. The system has been implemented on an analog d...","Title: A Reconfigurable Hybrid Low Dropout Voltage Regulator for Wide-Range Power Supply Noise Rejection and Energy-Efficiency Trade-Off.\nYear: 2018\n\nAbstract: A scan-reconfigurable hybrid low dropout (LDO) macro with four operating modes to support tuning across a wide range of power supply noise rejection and power efficiency is presented. The configurations include: 1) a full-digital LDO; 2) an analog loop in parallel with a digital loop in switched mode control; 3) an analog LDO in parallel with discrete current sources; and 4) discrete current sourc...","Title: Dynamics of Coupled Systems and their Computing Properties Invited Paper : Invited Paper\nYear: 2018\n\nAbstract: Collective dynamical systems offer unique opportunities for computing by harnessing the complex interactions of simple elements such as oscillators or spike generators. This is possible when such dynamics can be programmed, controlled, and observed. In this talk, we will present some of our work where we are exploring the time-evolution of both deterministic and stochastic dynamical systems in both CMOS and post-CMOS computing substrates. Such systems find applications in solving inverse problems, distributed optimizations (convex and combinatorial) and machine learning. In this paper we will discuss our recent work that connects dynamics and algebraic graph theory. We will talk about implementation of such dynamics in mixed-signal CMOS, including a recent demonstration of reinforcement learning for energy-constrained edge devices. We will conclude with a brief discussion of the opportunities, potentials and challenges in realizing such computational systems.","Title: A 55-nm, 1.0–0.4V, 1.25-pJ/MAC Time-Domain Mixed-Signal Neuromorphic Accelerator With Stochastic Synapses for Reinforcement Learning in Autonomous Mobile Robots\nYear: 2019\n\nAbstract: Reinforcement learning (RL) is a bio-mimetic learning approach, where agents can learn about an environment by performing specific tasks without any human supervision. RL is inspired by behavioral psychology, where agents take actions to maximize a cumulative reward. In this paper, we present an RL neuromorphic accelerator capable of performing obstacle avoidance in a mobile robot at the edge of the cloud. We propose an energy-efficient time-domain mixed-signal (TD-MS) computational framework. In TD-MS computation, we demonstrate that the energy to compute is proportional to the importance of the computation. We leverage the unique properties of stochastic networks and recent advances in Q-learning in the proposed RL implementation. The 55-nm test chip implements RL using a three-layered fully connected neural network and consumes a peak power of 690 \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\mu \\text{W}$ </tex-math></inline-formula>\n.","Title: Computing With Networks of Oscillatory Dynamical Systems.\nYear: 2019\n\nAbstract: As we approach the end of the silicon road map, alternative computing models that can solve at-scale problems in the data-centric world are becoming important. This is accompanied by the realization that binary abstraction and Boolean logic, which have been the foundations of modern computing revolution, fall short of the desired performance and power efficiency. In particular, hard computing prob...","Title: 14.1 A 65nm 1.1-to-9.1TOPS/W Hybrid-Digital-Mixed-Signal Computing Platform for Accelerating Model-Based and Model-Free Swarm Robotics\nYear: 2019\n\nAbstract: Artificial swarm intelligence, inspired by biological studies of insects, ants and other organisms, present an emerging computing paradigm, where seemingly simple elements interact with each other to collectively solve challenging problems. In particular, swarm robotics, where multiple robots co-ordinate in real-time to solve diverse problems such as pattern-formation, cooperative reinforcement learning (RL), path-planning etc. [1], find extensive uses in exploration, reconnaissance and disaster relief. This is partly motivated by the robustness of swarm dynamics to failures and malfunctions of individual robots. Successful hardware demonstrations of neuro-inspired algorithms on edge-devices [2]–[6] is now leading to the emergence of intelligence and control in swarms as the next frontier. Although certain swarm algorithms rely on real-time learning (e.g., cooperative RL) representing a model-free approach, many powerful algorithms that have been developed over the past two decades (e.g., pattern formation) rely on a mathematical structure and represent a more traditional model-based approach. The next generation of swarm hardware needs to support both of these approaches. In this paper, we identify the commonalities and shared compute primitives across a variety of model-based and model-free swarm algorithms and present a unified, fully-programmable, energy-efficient and scalable platform capable of real-time swarm intelligence.","Title: Test and Reliability of Emerging Non-volatile Memories\nYear: 2017\n\nAbstract: The search for alternative memory technologies has attracted significant attention toward emerging non-volatile memories. Among them, STT-MRAM, PCM, RRAM have shown promising characteristic to gain a position inside the memory hierarchy of computing platforms, and even enable new computing paradigms. However like any other emerging technology these devices are affected by concerns to be resolved before they could become a mainstream. This paper reviews the main reliability and testability challenges of aforementioned emerging non-volatile memories and highlights the main future considerations toward them.","Title: ASNI: Attenuated Signature Noise Injection for Low-Overhead Power Side-Channel Attack Immunity.\nYear: 2018\n\nAbstract: Computationally-secure cryptographic algorithms implemented on a physical platform leak significant “side-channel” information through their power supplies. Correlational power attack is an efficient power side-channel attack (SCA) technique, which analyzes the statistical correlation between the estimated and the measured supply current traces to extract the secret key. The existing power SCA cou...","Title: A FeFET Based Processing-In-Memory Architecture for Solving Distributed Least-Square Optimizations\nYear: 2018\n\nAbstract: HfO\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n based ferroelectric FET (FeFET) has recently received great interest for its application in nonvolatile memory (NVM) [1]. Unlike conventional perovskite based ferroelectric materials, HfO\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n is CMOS compatible and retains ferroelectricity for thin film with thickness around 10 nm. Therefore, successful integration of ferroelectric HfO\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n into advanced CMOS technology makes this technology highly promising for NVM [1]. Moreover, by tuning the portion of switched ferroelectric domain, a FeFET can exhibit multiple intermediate states, which enables its application as an analog conductance in mixed-signal in-memory computing. Currently, such architectures have been applied to neuromorphic computing [2], [3]. In this paper, we present a processing-in-memory (PIM) architecture with FeFETs and demonstrate how this can be used to solve a new class of optimization problems, in particular, distributed least square minimization.","Title: Context-Aware Intelligence in Resource-Constrained IoT Nodes: Opportunities and Challenges.\nYear: 2019\n\nAbstract: Editor's note: This article provides an academic perspective of the problem, starting with a survey of recent advances in intelligent sensing, computation, communication, and energy management for resource-constrained IoT sensor nodes and leading to a future outlook and needs. -Shreyas Sen, Purdue University.","Title: Guest Editors' Introduction: Intelligent Resource-Constrained Sensor Nodes.\nYear: 2019\n\nAbstract: Following continued system miniaturization for over past five decades, the size of unit computing has been steadily shrinking. In the foreseeable future, computing will be all around us, in mostly invisible forms, and is expected to lead more than 50 billion Internet-of-Things (IoT) devices, at the forefront of which will be distributed sensing nodes acting as the eyes and ears of IoT.","Title: Transfer And Online Reinforcement Learning In Stt-Mram Based Embedded Systems For Autonomous Drones\nYear: 2019\n\nAbstract: In this paper we present an algorithm-hardware co design for camera-based autonomous flight in small drones. We show that the large write-latency and write-energy for nonvolatile memory (NVM) based embedded systems makes them unsuitable for real-time reinforcement learning (RL), We address this by performing transfer learning (TL) on meta environments and RL on the last few layers of a deep convolutional network. While the NVM stores the meta-model from TL, an on-die SRAM stores the weights of the last few layers. Thus all the real-time updates sia RL are carried out on the SRAM arrays. This provides us with a practical platform with comparable performance as end-to-end RL and 83.4% lower energy per image frame.","Title: X-DeepSCA: Cross-Device Deep Learning Side Channel Attack\nYear: 2019\n\nAbstract: This article, for the first time, demonstrates Cross-device Deep Learning Side-Channel Attack (X-DeepSCA), achieving an accuracy of > 99.9%, even in presence of significantly higher inter-device variations compared to the inter-key variations. Augmenting traces captured from multiple devices for training and with proper choice of hyper-parameters, the proposed 256-class Deep Neural Network (DNN) learns accurately from the power side-channel leakage of an AES-128 target encryption engine, and an N-trace (N ≤ 10) X-DeepSCA attack breaks different target devices within seconds compared to a few minutes for a correlational power analysis (CPA) attack, thereby increasing the threat surface for embedded devices significantly. Even for low SNR scenarios, the proposed X-DeepSCA attack achieves ~ 10× lower minimum traces to disclosure (MTD) compared to a traditional CPA.","Title: Direct Feedback Alignment with Sparse Connections for Local Learning.\nYear: 2019\n\nAbstract: Recent advances in deep neural networks (DNNs) owe their success to training algorithms that use backpropagation and gradient-descent. Backpropagation, while highly effective on von Neumann architectures, becomes inefficient when scaling to large networks. Commonly referred to as the weight transport problem, each neuron's dependence on the weights and errors located deeper in the network require exhaustive data movement which presents a key problem in enhancing the performance and energy-efficiency of machine-learning hardware. In this work, we propose a bio-plausible alternative to backpropagation drawing from advances in feedback alignment algorithms in which the error computation at a single synapse reduces to the product of three scalar values. Using a sparse feedback matrix, we show that a neuron needs only a fraction of the information previously used by the feedback alignment algorithms. Consequently, memory and compute can be partitioned and distributed whichever way produces the most efficient forward pass so long as a single error can be delivered to each neuron. We evaluate our algorithm using standard datasets, including ImageNet, to address the concern of scaling to challenging problems. Our results show orders of magnitude improvement in data movement and 2x improvement in multiply-and-accumulate operations over backpropagation. Like previous work, we observe that any variant of feedback alignment suffers significant losses in classification accuracy on deep convolutional neural networks. By transferring trained convolutional layers and training the fully connected layers using direct feedback alignment, we demonstrate that direct feedback alignment can obtain results competitive with backpropagation. Furthermore, we observe that using an extremely sparse feedback matrix, rather than a dense one, results in a small accuracy drop while yielding hardware advantages. All the code and results are available under https://github.com/bcrafton/ssdfa.","Title: Efficient Signal Reconstruction Via Distributed Least Square Optimization On A Systolic Fpga Architecture\nYear: 2019\n\nAbstract: Optimization problems form the basis of a wide gamut of computationally challenging tasks in signal processing, machine learning, resource planning and so on. Out of these, convex optimization, and in particular least square optimization, covers a vast majority; and recent advances in iterative algorithms to solve such problems of large dimensions have gained traction. Multi-core designs with systolic or semisystolic architectures can be a key enabler for implementing discrete dynamical systems and realize massively scalable architectures to solve such optimization algorithms. In this paper, we present a platform architecture implemented in programmable FPGA hardware to solve a template problem in distributed optimization, namely signal reconstruction from non-uniform sampling. This is a quintessential problem with wide-spread applications in signal processing, computational imaging etc. We expect such an architectural exploration to open up promising opportunities to solve distributed optimizations that are becoming increasingly important in real-world applications. The complete system design, mapping and optimization into an FPGA architecture as well as analysis of convergence and scalability have been presented.","Title: Statistical optimization of compute in-memory performance under device variation\nYear: 2021\n\nAbstract: ABSTRACTCompute in-memory (CIM) is a promising technique that minimizes data transport, maximizes memory throughput, and performs computation on the bitline of memory sub-arrays. Utilizing embedded non-volatile memories (eNVM) such as resistive random access memory (RRAM), various forms of neural networks can be implemented. Unfortunately, CIM faces new challenges traditional CMOS architectures have avoided. In this work, we explore the impact of device variation (calibrated with measured data on foundry RRAM arrays) and propose a new algorithm based on device variation to increase both performance and accuracy for CIM designs. We demonstrate up to 36% power improvement and 44% performance improvement, while satisfying any error constraint.","Title: Hardware-Algorithm Co-Design Enabling Efficient Event-based Object Detection\nYear: 2021\n\nAbstract: Event-based cameras are a promising alternative to traditional optical cameras for real time computer vision systems. They offer low power, high temporal resolution, and high dynamic range, making them an ideal candidate for resource-constrained edge computing. In this work, we evaluate system level designs using event-based cameras for computer vision on the edge. We present a new technique to im...","Title: RAPID-RL: A Reconfigurable Architecture with Preemptive-Exits for Efficient Deep-Reinforcement Learning\nYear: 2022\n\nAbstract: Present-day Deep Reinforcement Learning (RL) systems show great promise towards building intelligent agents surpassing human-level performance. However, the computational complexity associated with the underlying deep neural networks (DNNs) leads to power-hungry implementations. This makes deep RL systems unsuitable for deployment on resource-constrained edge devices. To address this challenge, we propose a reconfigurable architecture with preemptive exits for effi-cient deep RL (RAPID-RL). RAPID-RL enables conditional activation of DNN layers based on the difficulty level of inputs. This allows to dynamically adjust the compute effort during inference while maintaining competitive performance. We achieve this by augmenting a deep Q-network (DQN) with side-branches capable of generating intermediate predictions along with an associated confidence score. We also propose a novel training methodology for learning the actions and branch confidence scores in a dynamic RL setting. Our experiments evaluate the proposed framework for Atari 2600 gaming tasks and a realistic Drone navigation task on an open-source drone simulator (PEDRA). We show that RAPID-RL incurs 0.34 × (0.25 ×) number of operations (OPS) while maintaining performance above 0.88 × (0.91 ×) on Atari (Drone navigation) tasks, compared to a baseline-DQN without any side-branches. The reduction in OPS leads to fast and efficient inference, proving to be highly beneficial for the resource-constrained edge where making quick decisions with minimal compute is essential.","Title: Analyzing and Improving Fault Tolerance of Learning-Based Navigation Systems\nYear: 2021\n\nAbstract: Learning-based navigation systems are widely used in autonomous applications, such as robotics, unmanned vehicles and drones. Specialized hardware accelerators have been proposed for high-performance and energy-efficiency for such navigational tasks. However, transient and permanent faults are increasing in hardware systems and can catastrophically violate tasks safety. Meanwhile, traditional redundancy-based protection methods are challenging to deploy on resource-constrained edge applications. In this paper, we experimentally evaluate the resilience of navigation systems with respect to algorithms, fault models and data types from both RL training and inference. We further propose two efficient fault mitigation techniques that achieve 2x success rate and 39% quality-of-flight improvement in learning-based navigation systems.","Title: A 40-nm, 64-Kb, 56.67 TOPS/W Voltage-Sensing Computing-In-Memory/Digital RRAM Macro Supporting Iterative Write With Verification and Online Read-Disturb Detection\nYear: 2022\n\nAbstract: Computing-in-memory (CIM) architectures have gained importance in achieving high-throughput energy-efficient artificial intelligence (AI) systems. Resistive RAM (RRAM) is a promising candidate for CIM architectures due to a multiply-and-accumulate (MAC)-friendly structure, high bit density, compatibility with a CMOS process, and nonvolatility. Notwithstanding the advancement of RRAM technology, th...","Title: A decentralized policy gradient approach to multi-task reinforcement learning.\nYear: 2021\n\nAbstract: We develop a mathematical framework for solving multi-task reinforcement learning (MTRL) problems based on a type of policy gradient method. The goal in MTRL is to learn a common policy that operates effectively in different environments; these environments have similar (or overlapping) state spaces, but have different rewards and dynamics. We highlight two fundamental challenges in MTRL that are not present in its single task counterpart, and illustrate them with simple examples. We then develop a decentralized entropyregularized policy gradient method for solving the MTRL problem, and study its finite-time convergence rate. We demonstrate the effectiveness of the proposed method using a series of numerical experiments. These experiments range from small-scale \"GridWorld\" problems that readily demonstrate the trade-offs involved in multi-task learning to large-scale problems, where common policies are learned to navigate an airborne drone in multiple (simulated) environments.","Title: An Energy-Efficient and Runtime-Reconfigurable FPGA-Based Accelerator for Robotic Localization Systems\nYear: 2022\n\nAbstract: A robot usually localizes itself in an environment by estimating the collection of its position and rotation states, while constructing a map of unknown surroundings, giving rise to the notion of Simultaneous Localization and Mapping (SLAM). SLAM is a fundamental kernel in autonomous machines at all computing scales, from drones, AR, VR to self-driving cars. Principled mathematical solutions for SLAM involve filtering-based or non-linear optimization-based (Fig. 1a), where the latter recently shows higher robustness but with intensive computation. Prior ASICs [1], [2] and FPGAs [3], [4], [5] have accelerated SLAM on hardware, but they usually target one specific design. In this work, we present a runtime-reconfigurable FPGA accelerator for robotic localization tasks. We exploit SLAM-specific data locality, sparsity, reuse, and parallelism, and achieve >5x performance improvement over the state-of-the-art. Especially, our design is reconfigurable at runtime according to the environment and platform to save power while sustaining accuracy and performance.","Title: FRL-FI: Transient Fault Analysis for Federated Reinforcement Learning-Based Navigation Systems\nYear: 2022\n\nAbstract: Swarm intelligence is being increasingly deployed in autonomous systems, such as drones and unmanned vehicles. Federated reinforcement learning (FRL), a key swarm intelligence paradigm where agents interact with their own environments and cooperatively learn a consensus policy while preserving privacy, has recently shown potential advantages and gained popularity. However, transient faults are increasing in the hardware system with continuous technology node scaling and can pose threats to FRL systems. Meanwhile, conventional redundancy-based protection methods are challenging to deploy on resource-constrained edge applications. In this paper, we experimentally evaluate the fault tolerance of FRL navigation systems at various scales with respect to fault models, fault locations, learning algorithms, layer types, communication intervals, and data types at both training and inference stages. We further propose two cost-effective fault detection and recovery techniques that can achieve up to \n<tex xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">$3.3\\times$</tex>\n improvement in resilience with \n<tex xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">$<2.7\\%$</tex>\n overhead in FRL systems.","Title: Robotic Computing on FPGAs: Current Progress, Research Challenges, and Opportunities\nYear: 2022\n\nAbstract: Robotic computing has reached a tipping point, with a myriad of robots (e.g., drones, self-driving cars, logistic robots) being widely applied in diverse scenarios. The continuous proliferation of robotics, however, critically depends on efficient computing substrates, driven by real-time requirements, robotic size-weight-and-power constraints, cybersecurity considerations, and dynamically changing scenarios. Within all platforms, FPGA is able to deliver both software and hardware solutions with low power, high performance, reconfigurability, reliability, and adaptivity characteristics, serving as the promising computing substrate for robotic applications. This paper highlights the current progress, design techniques, challenges, and open research challenges in the domain of robotic computing on FPGAs.","Title: A Practical Design-Space Analysis of Compute-in-Memory With SRAM\nYear: 2022\n\nAbstract: Analog-domain compute-in-memory (CIM) is a technique that has emerged in part as a response to the memory-intensive vector-matrix-multiplications (VMMs) required to implement important emerging applications, notably machine learning inference. Implemented CIM systems have demonstrated good energy efficiency for lower-precision systems and/or with loosened compute-level accuracy requirements. A ...","Title: BitS-Net: Bit-Sparse Deep Neural Network for Energy-Efficient RRAM-Based Compute-In-Memory\nYear: 2022\n\nAbstract: The rising popularity of intelligent mobile devices and the computational cost of deep learning-based models call for efficient and accurate on-device inference schemes. We propose a novel model compression scheme that allows inference to be carried out using bit-level sparsity, which can be efficiently implemented using in-memory computing macros. In this paper, we introduce a method called BitS-Net to leverage the benefits of bit-sparsity (where the number of zeros are more than number of ones in binary representation of weight/activation values) when applied to compute-in-memory (CIM) with resistive RAM (RRAM) to develop energy efficient DNN accelerators operating in the inference mode. We demonstrate that BitS-Net improves the energy efficiency by up to 5x for ResNet models on the ImageNet dataset.","Title: A 65 nm Wireless Image SoC Supporting On-Chip DNN Optimization and Real-Time Computation-Communication Trade-Off via Actor-Critical Neuro-Controller\nYear: 2022\n\nAbstract: The widespread proliferation of smart sensors has led to hardware that enable edge intelligence (EI) with extreme energy efficiencies. This decreases the volume of data that is transmitted to the cloud, thus reducing: 1) processing latency; 2) communication energy; and 3) network congestion. However, this comes with an added cost of computation at the edge node. The cost (energy/latency) of edge computation and the cost of communication to the cloud vary widely depending on operating conditions, which include: 1) information content in the data; 2) algorithm selection; 3) channel conditions (noise, path-loss, etc.); 4) network size, available bandwidth; and 5) resources at the cloud. This article presents a 65 nm wireless image processing SoC for real-time computation-communication trade-off on resource-constrained edge devices. The test-chip includes: 1) an all-digital, near-memory, reconfigurable, and programmable neural-network (NN)-based systolic image processor; 2) a digitally adaptive radio-frequency digital-to-analog converter (RF-DAC)-based transceiver; and 3) a mixed-signal, time-based, actor-critic (AC) neuro-controller with compute-in-memory (CIM) and in-place weight updates that provide online learning and adaptation for efficiently controlling the computation, communication blocks separately as well as jointly. The major contributions of the proposed SoC are threefold: 1) a wireless Internet of Things (IoT) SoC architecture enabling a generic computation-communication trade-off scheme; 2) a novel CIM circuit design enabling effective AC control and online learning (0.59 pJ/MAC, 0.4 pJ/update); 3) integration of programmable deep NN (DNN) accelerator (1.05 TOPS/W) and reconfigurable transceiver (184 pJ/b @ –15 dBm) supporting versatile cloud-edge collaborations; and 4) significant system-level energy efficiency improvement (5.7\n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\times $ </tex-math></inline-formula>\n) with real-time on-chip smart control enabled by seamless chip integration and AI-enabled decision-making. Furthermore, this SoC serves as a system-level IoT prototype for next-generation context-aware EI.","Title: An End-to-End Spiking Neural Network Platform for Edge Robotics: From Event-Cameras to Central Pattern Generation\nYear: 2022\n\nAbstract: Learning to adapt one’s gait with environmental changes plays an essential role in the locomotion of legged robots which remains challenging for constrained computing resources and energy budget, as in the case of edge-robots. Recent advances in bio-inspired vision with dynamic vision sensors (DVSs) and associated neuromorphic processing can provide promising solutions for end-to-end sensing, cognition, and control tasks. However, such bio-mimetic closed-loop robotic systems based on event-based visual sensing and actuation in the form of spiking neural networks (SNNs) have not been well explored. In this work, we program the weights of a bio-mimetic multigait central pattern generator (CPG) and couple it with DVS-based visual data processing to show a spike-only closed-loop robotic system for a prey-tracking scenario. We first propose a supervised learning rule based on stochastic weight updates to produce a multigait producing spiking-CPG (SCPG) for hexapod robot locomotion. We then actuate the SCPG to seamlessly transition between the gaits for a nearest prey tracking task by incorporating SNN-based visual processing for input event-data generated by the DVS. This for the first time, demonstrates the natural coupling of event data flow from event-camera through SNN and neuromorphic locomotion. Thus, we exploit bio-mimetic dynamics and energy advantages of spike-based processing for autonomous edge-robotics.","Title: A 90.4% Peak Efficiency 48V/1V Three-Level Hybrid Dickson Converter with Gradient Descent Run-Time Optimizer and GaN/Si Hybrid Conversion\nYear: 2022\n\nAbstract: This work presents a 48V/1V DC-DC Point-of-Load (POL) converter for efficient high voltage conversion in data centers. The converter includes (1) a three-level hybrid Dickson topology with GaN/Si hybrid conversion achieving efficient flying capacitor (C\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">F</inf>\n) utilization. (2) A gradient descent run-time optimizer finding optimal switching frequency (f\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">SW</inf>\n) and number of fingers turned on (N\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">F</inf>\n) during converter’s operation. (3) A 10bit hybrid ADC for current sensing. The test chip is fabricated in 0.18μm BCD process and shows a 90.4% peak efficiency at 48V-1V conversion with a 240 A/inch\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">3</sup>\n current density.","Title: A low power and PVT variation tolerant mux-latch for serializer interface and on-chip serial link\nYear: 2022\n\nAbstract: Multiplexer (mux) latch is one of the key components for serializer interface to admit communication at Gbps. This work describes the working of a 2:1 mux-latch coupled to a power delivery network (PDN) and a CPU core drawing abrupt current. In comparison to conventional designs, multiplexer and latch operate at the same time, which is quite different because enable inputs are imperative to start latch operation. An analytical model is also derived to understand power delay trade-off and to choose gate sizes to obtain a comparable delay without increasing power. The average power and delay in post-layout are 257.7 μW and 35 ps, respectively, in a 90-nm CMOS, power supply voltage (Vdd) of 1.1 V and a clock switching at 6.25 GHz. However, a 117OC change in temperature at distinct corner allows average power to vary between 32.8 and 64 μW. The corresponding variation is 135–183.7 μW as Vdd switches from 0.75 to 1.1 V. In addition to so, delay changes between 5-14 ps and 3–12 ps for the given change in temperature and Vdd, respectively. Nonetheless, the effective supply voltage VP oscillates with time as the CPU core draws abrupt current. The delay values due to AC noise are found to be different than VP having no noise and the corresponding jitter changes linearly as a function of noise.","Title: Gradient Backpropagation based Feature Attribution to Enable Explainable-AI on the Edge\nYear: 2022\n\nAbstract: There has been a recent surge in the field of Explainable AI (XAI) which tackles the problem of providing insights into the behavior of black-box machine learning models. Within this field, feature attribution encompasses methods which assign relevance scores to input features and visualize them as a heatmap. Designing flexible accelerators for multiple such algorithms is challenging since the hardware mapping of these algorithms has not been studied yet. In this work, we first analyze the dataflow of gradient backpropagation based feature attribution algorithms to determine the resource overhead required over inference. The gradient computation is optimized to minimize the memory overhead. Second, we develop a High-Level Synthesis (HLS) based configurable FPGA design that is targeted for edge devices and supports three feature attribution algorithms. Tile based computation is employed to maximally use on-chip resources while adhering to the resource constraints. Representative CNNs are trained on CIFAR-10 dataset and implemented on multiple Xilinx FPGAs using 16-bit fixed-point precision demonstrating flexibility of our library. Finally, through efficient reuse of allocated hardware resources, our design methodology demonstrates a pathway to repurpose inference accelerators to support feature attribution with minimal overhead, thereby enabling real-time XAI on the edge.","Title: An Analog Clock-free Compute Fabric base on Continuous-Time Dynamical System for Solving Combinatorial Optimization Problems\nYear: 2022\n\nAbstract: NP-hard combinatorial optimization problems (COPs) are known to be very complex and expensive to solve with traditional computers. COPs can be mapped onto many different kinds of architecture, such as fully digital [1]–[3], event based [4], oscillators [5]–[6], Optical LASER [7], Qbits, or pure analog approach [8]–[9]. We propose a scalable pure analog clock-free continuous-time dynamical system to solve COPs in hardware.","Title: Towards CIM-friendly and Energy-Efficient DNN Accelerator via Bit-level Sparsity\nYear: 2022\n\nAbstract: The rising popularity of deep neural network (DNN) algorithms calls for energy-efficient accelerators to enable DNNs run on edge devices. In this paper, we presented BitS-Net, a bit-level sparsity method that quantize the network to desirable numbers with more zeros in their bit representation. We demonstrated that BitS-Net can preserve the accuracy (67.73 %) with accuracy drop ¡1% compared to the original network. Moreover, it achieved up to 5x energy efficiency for ResNet-18 models on the ImageNet dataset compared to the baseline methods.","Title: Towards Energy Efficient DNN accelerator via Sparsified Gradual Knowledge Distillation\nYear: 2022\n\nAbstract: Artificial intelligence (AI) is becoming increasingly popular in many applications. However, the computation cost of deep neural network (DNN) , which is a powerful form of AI, calls for efficient DNN compression technique to make energy efficient networks. In this paper, we proposed SKG, a method to jointly sparsify and quantize DNN models to ultra-low bit-precision using Knowledge Distillation and gradual quantization (SKG). We demonstrated that our method can preserve the accuracy more than 20% for uniform quantization with 2 bit-width compared to the baseline methods on ImageNet and ResNet-18. In addition, our method can achieve up to 2.7x lower energy consumption using compute-in-memory (CIM) architecture compared to a traditional 65nm CMOS architecture for both pruned and unpruned network during inference and eventually enabling using DNN models on resource constrained edge devices.","Title: Design Space Exploration of Interconnect Materials for Cryogenic Operation: Electrical and Thermal Analyses\nYear: 2022\n\nAbstract: With Copper (Cu) Interconnects causing performance bottleneck at single nanometer nodes due to increase in resistivity size effects viz., grain boundary scattering and surface scattering, there has always been scavenging for alternate interconnect materials. Although the Cu resistivity value decreases at cryogenic temperature, the problems continue to persist. In this work, we study three alternate interconnect materials specifically for 77K High Performance Compute applications. We select the materials based on their resistivity value at 77K for 7nm node computed using Fuchs-Sondheimer-Mayadas-Shatzkes (FS-MS) models. We analyze the delay of the interconnects, understand repeater insertion as a function of wire length, evaluate repeater count and energy at system level and perform IR drop analysis by showing through detailed analytical models that Ru, Rh and Al can provide appreciable improvements over Cu at 77K. The delay of interconnects reduces by 1-3.75% for Ru, 1.5-7.25% for Rh and 4.4-17.8% for Al across the BEOL stack while repeater counts decrease by 10%, 15% and 37% for Ru, Rh and Al respectively at 77K. We investigate thermal and reliability aspects of interconnect design including electromigration, Joule Heating and maximum allowed current densities again proving that Ru (9%), Rh (18%) and Al (63%) outperform Cu at 77K. Finally, we study the effects of various Low-k dielectric materials on the interconnect capacitance and thermal behavior for Cu as well as three alternate materials noting that, even though thermal conductivity of dielectrics decrease at 77K, the Joule Heating will not be as worse as one might expect."],"string":"[\n \"Title: A 1.05 V 1.6 mW, 0.45 <formula formulatype=\\\"inline\\\"> <tex Notation=\\\"TeX\\\">$^{\\\\circ}$</tex></formula>C 3<formula formulatype=\\\"inline\\\"> <tex Notation=\\\"TeX\\\">$\\\\sigma$</tex></formula> Resolution <formula formulatype=\\\"inline\\\"> <tex Notation=\\\"TeX\\\">$\\\\Sigma\\\\Delta$</tex></formula> Based Temperature Sensor With Parasitic Resistance Compensation in 32 nm Digital CMOS Process\\nYear: 2009\\n\\nAbstract: Monitoring temperature in a microprocessor is important for optimal energy consumption under various workloads. This paper presents a temperature sensor in a 32 nm high-k metal gate digital CMOS process for integration in a microprocessor core. The sensor uses a ratio of currents driven into a BJT pair with current chopping to up-convert the temperature signal. A second order sigma-delta (ΣΔ) 1-bi...\",\n \"Title: Neuro Inspired Computing with Coupled Relaxation Oscillators\\nYear: 2014\\n\\nAbstract: Harnessing the computational capabilities of dynamical systems has attracted the attention of scientists and engineers form varied technical disciplines over decades. The time evolution of coupled, non-linear synchronous oscillatory systems has led to active research in understanding their dynamical properties and exploring their applications in brain-inspired, neuromorphic computational models. In this paper we present the realization of coupled and scalable relaxation-oscillators utilizing the metal-insulator-metal transition of vanadium-dioxide (VO2) thin films. We demonstrate the potential use of such a system in pattern recognition, as one possible computational model using such a system.\",\n \"Title: Analysis of super cut-off transistors for ultralow power digital logic circuits\\nYear: 2006\\n\\nAbstract: Super cut-off devices with sub-60mV/decade subthreshold swings have recently been demonstrated and being extensively studied. This paper presents a feasibility analysis of such tunneling devices for ultralow power subthreshold logic. Analysis shows that this device can deliver 800X higher performance (@iso-IOFF) compared to a MOSFET. The possible use of this device as a sleep transistor in conjunction with the regular Si MOSFET shows 2000X average improvement in leakage power compared to Si MOSFETs.\",\n \"Title: A high density, carbon nanotube capacitor for decoupling applications\\nYear: 2006\\n\\nAbstract: We present a novel application for carbon nanotube devices, implementing a high density 3-D capacitor, which can be useful for decoupling applications to reduce supply voltage variations. The capacitor consists of staggered layers of interleaved carbon nanotubes, alternately connected to anode and cathode contacts. The device can realize a capacitance/area, significantly larger than the ITRS's projected requirements for year 2018. The capacitance per unit area can exceed 1pF/μm2, with a quality factor greater than 100 at 1GHz.\",\n \"Title: TapeCache: a high density, energy efficient cache based on domain wall memory\\nYear: 2012\\n\\nAbstract: Domain Wall Memory (DWM) is a recently developed spin-based memory technology in which several bits of data are densely packed into the domains of a ferromagnetic wire. DWM has shown great promise in enabling non-volatile memory with unprecedented density and high energy efficiency. In this work, we propose TapeCache, a first attempt to employ DWMs as last-level caches in general purpose computing platforms. DWMs enable much higher density compared to SRAM, DRAM, and other spin-based memory technologies such as STT-MRAM. However, they also pose unique challenges such as serial access to the bits stored in a DWM cell, leading to variable access latencies. We propose a novel circuit-architecture co-design for TapeCache, consisting of (i) a multi-port DWM macro-cell optimized for read operations considering the asymmetry in applications' read/write characteristics, and (ii) a new cache organization and suitable management policies that mitigate the performance penalty arising from serial access to bits in a macro-cell. Over a wide range of SPEC 2006 benchmarks, TapeCache achieves 7.8X improvement in area, an average energy improvement of 7.3X, and an average performance improvement of 1.2% compared to an iso-capacity SRAM cache. Compared to an iso-capacity STT-MRAM cache, TapeCache obtains 2.3X improvement in area and 1.4X average energy savings with virtually identical performance.\",\n \"Title: Computing with subthreshold leakage: device/circuit/architecture co-design for ultralow-power subthreshold operation\\nYear: 2005\\n\\nAbstract: This paper presents a novel design methodology for ultralow-power design using subthreshold leakage as the operating current (suitable for medium frequency of operation: tens to hundreds of millihertz). Standard design techniques suitable for super-threshold design can be used in the subthreshold region. However, in this study, it has been shown that a complete co-design at all levels of hierarchy (device, circuit, and architecture) is necessary to reduce the overall power consumption while achieving acceptable performance (hundreds of millihertz) in the subthreshold regime of operation. Simulation results of co-design on a five-tap finite-impulse-response filter shows ∼2.5 × improvement in throughput at iso-power compared to a conventional design.\",\n \"Title: Modeling of Ballistic Carbon Nanotube Field Effect Transistors for Efficient Circuit Simulation\\nYear: 2003\\n\\nAbstract: Carbon Nanotube Field-Effect Transistors (CNFETs) arebeing extensively studied as possible successors to CMOS.Novel device structures have been fabricated and devicesimulators have been developed to estimate theirperformance in a sub 10nm transistor era. This paperpresents a novel method of circuit-compatible modeling ofCNFETs in their ultimate performance limit. The model sodeveloped has been used to simulate arithmetic and logicblocks using HSPICE.\",\n \"Title: Modeling and analysis of system stability in a distributed power delivery network with embedded digital linear regulators.\\nYear: 2014\\n\\nAbstract: On-chip power delivery networks (PDNs) for today's microprocessors and systems-on-chip (SoCs), which are characterized by dynamic supply voltage, many embedded integrated VRs (IVRs), lower decoupling-capacitor, high current ranges, multiple power modes and fast transient loads are designed to minimize AC load transients and supply noise. The close interaction of the VRs with the power grids create multiple feedback paths in the overall network, compromising the resultant phase margin and can even lead to system instabilities. The introduction of digital linear regulators operating in the low dropout (LDO) mode, with low power supply rejection, further exacerbates the problem. This paper provides a comprehensive methodology, based on Mason's Gain Formula applied to hybrid control, for modeling and analyzing distributed linear regulators and their interaction with the PDN.\",\n \"Title: Modeling and analysis of digital linear dropout regulators with adaptive control for high efficiency under wide dynamic range digital loads\\nYear: 2014\\n\\nAbstract: Discrete time digital linear regulators, including low dropout regulators (LDOs) have become competitive in muti-Vcc digital systems for fine-grained spatio-temporal voltage regulation and distribution. However, wide dynamic current range of the digital load circuits poses serious problems in maintaining stability and high efficiency at all corners. In this paper we present a control model for discrete time LDOs and demonstrate how online adaptive control can be employed for consistent performance and high efficiency across the load current range.\",\n \"Title: Accurate estimation of total leakage current in scaled CMOS logic circuits based on compact current modeling\\nYear: 2003\\n\\nAbstract: Dramatic increase of subthreshold, gate and reverse biased junction band-to-band-tunneling (BTBT) leakage in scaled devices, results in the drastic increase of total leakage power in a logic circuit. In this paper a methodology for accurate estimation of the total leakage in a logic circuit based on the compact modeling of the different leakage current in scaled devices has been developed. Current models have been developed based on the exact device geometry, 2-D doping profile and operating temperature. A circuit level model of junction BTBT leakage (which is unprecedented) has been developed. Simple models of the subthreshold current and the gate current have been presented. Here, for the first time, the impact of quantum mechanical behavior of substrate electrons, on the circuit leakage has been analyzed. Using the compact current model, a transistor has been modeled as a Sum of Current Sources (SCS). The SCS transistor model has been used to estimate the total leakage in simple logic gates and complex logic circuits (designed with transistors of 25nm effective length) at the room and at the elevated temperatures.\",\n \"Title: A Feasibility Study of Subthreshold SRAM Across Technology Generations\\nYear: 2005\\n\\nAbstract: Abstract: In this paper we have explored the feasibility of designing an SRAM array in the subthreshold domain of device operation. We have performed a nominal corner analysis of power and stability and a statistical analysis of the different failure probablilities of the subthreshold SRAM. Our analysis shows that subthreshold SRAM gives significant reduction (~100X) of operating amd standby power at iso-performance (~100MHz) compared to the superthreshold counterpart. However, with increasing intra-die variation owing to technology scaling, the failure probability of subthreshold SRAM increases thereby masking the power benefits.\",\n \"Title: Delay Fault Localization in Test-Per-Scan BIST Using Built-In Delay Sensor\\nYear: 2006\\n\\nAbstract: Delay failures are becoming a dominant failure mechanism in nanometer technologies. Diagnosis of such failures is important to ensure yield and robustness of the design. However, the increasing circuit size limits the granularity of diagnosis, resulting in large suspect fault list. In this paper, we present a methodology for improving delay fault localization in test-per-scan BIST using on-die delay sensing at selective test points. It is demonstrated that the proposed technique can improve the resolution of fault localization for both transition and segment delay fault models. Experimental results for a set of ISCAS89 benchmarks show upto 49% (82%) average improvement in fault localization for transition (segment) delay fault models. The area overhead due to delay sensing hardware have been limited to 4%.\",\n \"Title: Design for test and reliability in ultimate CMOS\\nYear: 2012\\n\\nAbstract: This session brings together specialists from the DfT, DfY and DfR domains that will address key problems together with their solutions for the 14nm node and beyond, dealing with extremely complex chips affected by high defect levels, unpredictable and heterogeneous timing behavior, circuit degradation over time, including extreme situations related with the ultimate CMOS nodes, where all processor nodes, routers and links of single-chip massively parallel tera-device processors could comprise timing faults (such as delay faults or clock skews); a large percentage of these parts are affected by catastrophic failures; all parts experience significant performance degradations over time; and new catastrophic failures occur at low MTBF.\",\n \"Title: All-Digital Circuit-Level Dynamic Variation Monitor for Silicon Debug and Adaptive Clock Control.\\nYear: 2011\\n\\nAbstract: A 45 nm microprocessor integrates an all-digital dynamic variation monitor (DVM) to continuously measure the impact of dynamic parameter variations on circuit-level performance to enhance silicon debug and adaptive clock control. The DVM consists of a tunable replica circuit, a time-to-digital converter, and multiplexers to measure circuit delay or frequency changes with less than a 1% measured re...\",\n \"Title: Device optimization for ultra-low power digital sub-threshold operation\\nYear: 2004\\n\\nAbstract: Digital circuits operated in the sub-threshold region (supply voltage less than the transistor threshold voltage) can have orders of magnitude power advantage over standard CMOS circuits for applications requiring ultra-low power and medium frequency of operation. It is possible to implement sub-threshold logic circuits using the standard transistors that are designed primarily for ultra high performance super-threshold logic design. However, a Si MOSFET so optimized for performance in the super-threshold regime is not the best device to use in the sub-threshold domain. In this paper, we propose device designs apt for sub-threshold operation. Results show that the optimized device improves the delay and power delay product (PDP) of an inverter chain by 44% and 51%, respectively, over the normal super-threshold device operated in the sub-threshold region.\",\n \"Title: Leakage Power Analysis and Reduction for Nanoscale Circuits\\nYear: 2006\\n\\nAbstract: Leakage current in the nanometer regime has become a significant portion of power dissipation in CMOS circuits as threshold voltage, channel length, and gate oxide thickness scale downward. Various techniques are available to reduce leakage power in high-performance systems.\",\n \"Title: Carbon Nanotube Electronics: Design of High-Performance and Low-Power Digital Circuits\\nYear: 2007\\n\\nAbstract: Scaling of silicon transistors continue in the sub 100-nm regime amidst severe roadblocks. Increased short-channel effects, rising leakage currents, severe process parameter variations are only a few of the overwhelming challenges that the device and circuit designers are faced with. In an attempt to alleviate the problems associated with the scaling of silicon transistors, researchers have began ...\",\n \"Title: A circuit model for carbon nanotube interconnects: comparative study with Cu interconnects for scaled technologies\\nYear: 2004\\n\\nAbstract: Semiconducting carbon nanotubes (CNT) have gained immense popularity as possible successors to silicon as the channel material for ultra high performance field effect transistors. On the other hand, their metallic counterparts have often been regarded as ideal interconnects for the future technology generations. Owing to their high current densities and increased reliability, metallic-single walled CNTs (SWCNTs) have been subjects of fundamental research both in theory as well as experiments. Metallic CNTs have been modeled for RF applications in (Burke, 2003) using an LC model. We present an efficient circuit compatible RLC model for metallic SW CNTs, and analyze the impact of SW CNTs on the performance of ultra scaled digital VLSI design.\",\n \"Title: A Novel Low-overhead Delay Testing Technique for Arbitrary Two-Pattern Test Application\\nYear: 2005\\n\\nAbstract: With increasing process fluctuations in nano-scale technology, testing for delay faults is becoming essential in manufacturing test to complement stuck-at-fault testing. Design-for-testability techniques,such as enhanced scan are typically associated with considerable overhead in die-area,circuit performance, and power during normal mode of operation. This paper presents a novel test technique, which can be used as an alternative to the enhanced scan based delay fault testing method, with significantly less design overhead. Instead of using an extra latch as in the enhanced scan method, we propose using supply gating at the first level of logic gates to hold the state of a combinational circuit. Experimental results on a set of ISCAS89 benchmarks show an average reduction of 33% in area overhead with an average improvement of 71% in delay overhead and 90% in power overhead during normal mode of operation, compared to the enhanced scan implementation.\",\n \"Title: Effectiveness Of Energy Recovery Techniques In Reducing On-Chip Power Density In Molecular Nano-Technologies\\nYear: 2004\\n\\nAbstract: As scaling of silicon devices continues at an aggressive pace, the problems associated with it are becoming more and more evident. With 'short channel effects' already in the way of scaling, interest has shifted to the possible use of non-silicon molecular devices for circuit implementation. Carbon nanotube has emerged as a promising candidate. However, molecular devices such as Carbon Nanotube FETs (CNFETs) with their super-scaled dimensions and high current densities would increase the power density on chip and reasonable predictions estimate that they would far exceed the maximum power density limitation [2]. This paper explores the use of energy-recovery techniques in molecular CNFET based digital circuits and demonstrates how they can solve the power density problem in such circuits.\",\n \"Title: A 45 nm Resilient Microprocessor Core for Dynamic Variation Tolerance\\nYear: 2011\\n\\nAbstract: A 45 nm microprocessor core integrates resilient error-detection and recovery circuits to mitigate the clock frequency (FCLK) guardbands for dynamic parameter variations to improve throughput and energy efficiency. The core supports two distinct error-detection designs, allowing a direct comparison of the relative trade-offs. The first design embeds error-detection sequential (EDS) circuits in critical paths to detect late timing transitions. In addition to reducing the Fclk guardbands for dynamic variations, the embedded EDS design can exploit path-activation rates to operate the microprocessor faster than infrequently-activated critical paths. The second error-detection design offers a less-intrusive approach for dynamic timing-error detection by placing a tunable replica circuit (TRC) per pipeline stage to monitor worst-case delays. Although the TRCs require a delay guardband to ensure the TRC delay is always slower than critical-path delays, the TRC design captures most of the benefits from the embedded EDS design with less implementation overhead. Furthermore, while core min-delay constraints limit the potential benefits of the embedded EDS design, a salient advantage of the TRC design is the ability to detect a wider range of dynamic delay variation, as demonstrated through low supply voltage (VCC) measurements. Both error-detection designs interface with error-recovery techniques, enabling the detection and correction of timing errors from fast-changing variations such as high-frequency VCC droops. The microprocessor core also supports two separate error-recovery techniques to guarantee correct execution even if dynamic variations persist. The first technique requires clock control to replay errant instructions at 1/2FCLK. In comparison, the second technique is a new multiple-issue instruction replay design that corrects errant instructions with a lower performance penalty and without requiring clock control. Silico- - n measurements demonstrate that resilient circuits enable a 41% throughput gain at equal energy or a 22% energy reduction at equal throughput, as compared to a conventional design when executing a benchmark program with a 10% VCC droop. In addition, the microprocessor includes a new adaptive clock control circuit that interfaces with the resilient circuits and a phase-locked loop (PLL) to track recovery cycles and adapt to persistent errors by dynamically changing Fclk f°Γ maximum efficiency.\",\n \"Title: Leakage Current Based Stabilization Scheme for Robust Sense-Amplifier Design for Yield Enhancement in Nano-scale SRAM\\nYear: 2005\\n\\nAbstract: In this paper, we develop a method to analyze the probability of access failure in SRAM array (due to random Vt variation in transistors) by jointly considering variations in cell and senseamplifiers. Our analysis shows that, improving robustness of senseamplifier is extremely important for reducing memory access failure probability and improving yield. We present a process variation tolerant sense amplifier suitable for SRAM array designed in sub- 100nm CMOS technologies. The proposed technique reduces the failure probability of sense amplifiers by more than 80% with negligible penalty in the sensing delay.\",\n \"Title: Error Detection and Correction in Microprocessor Core and Memory Due to Fast Dynamic Voltage Droops\\nYear: 2011\\n\\nAbstract: Built-in resiliency features enable a microprocessor to detect and correct errors due to fast dynamic voltage droop events as well as other types of dynamic variations. Timing errors in the microprocessor core as well as read (RD) and write (WR) errors in the 8T SRAM based cache can be detected. As a result, guardbands added for these variations are reduced or eliminated, improving performance and reducing power consumption. Measurements on a 45 nm research microprocessor core demonstrate 41% improvement in throughput or 22% reduction in energy at 0.8 V. Measurements on the cache demonstrate reduction of the minimum operating Vcc (VMIN) by 9% thereby resulting in a 7.5% reduction of net operating power.\",\n \"Title: Arbitrary Two-Pattern Delay Testing Using a Low-Overhead Supply Gating Technique\\nYear: 2008\\n\\nAbstract: With increasing defect density and process variations in nanometer technologies, testing for delay faults is becoming essential in manufacturing test to complement stuck-at-fault testing. This paper presents a novel test technique based on supply gating, which can be used as an alternative to the enhanced scan based delay fault testing, with significantly less design overhead. Experimental results on a set of ISCAS89 benchmarks show an average reduction of 34% in area overhead with an average improvement of 65% in delay overhead and 90% in power overhead during normal mode of operation, compared to the enhanced scan implementation.\",\n \"Title: Frequency Specification Testing of Analog Filters Using Wavelet Transform of Dynamic Supply Current\\nYear: 2004\\n\\nAbstract: The wavelet transform has the property of resolving the signal in both time and frequency, unlike the Fourier transform. In this work, we show that time-domain information obtained from wavelet analysis of the supply current can be used to efficiently test the frequency specification of analog filters. The pole/zero locations in the frequency response of analog filters shift due to changes in component values with process variations. It is essential to test the filters for the shift in frequency response and fix it, during production test. Wavelet analysis of the supply current can be a promising alternative to test the frequency specification of analog filters, since it needs only one ac stimulus and is virtually unaffected by transistor threshold variation. Simulation results on two test circuits demonstrate that we can estimate the pole/zero shift with less than 3% error using only one measurement, which requires about 18 measurements in the conventional technique.\",\n \"Title: Beyond charge based computation: Design space exploration of spin transfer torque based MRAMs for embedded applications.\\nYear: 2013\\n\\nAbstract: Ever larger on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1–3]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin torque transfer (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The minimum size cell (mincell) contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3Fx2F=6F2. In this paper, we examine the design space for key magnetic material properties and access transistor needed for embedded on-die memory with adequate scalability, density, read/write performance and robustness against various intrinsic variabilities and disturbances. New models and simulation methodologies, calibrated to existing measurements [1], for read, write and disturbance mechanisms are developed. Different storage node structures and materials are evaluated to reveal the mos- promising scaling options.\",\n \"Title: Defect Oriented Testing of Analog Circuits Using Wavelet Analysis of Dynamic Supply Current\\nYear: 2005\\n\\nAbstract: In recent years, Defect Oriented Testing (DOT) has been investigated as an alternative testing method for analog circuits. In this paper, we propose a wavelet transform based dynamic supply current (IDD) analysis technique for detecting catastrophic and parametric faults in analog circuits. Wavelet transform has the property of resolving events in both time and frequency domain simultaneously unlike Fourier transform which decomposes a signal in frequency components only. Simulation results on benchmark circuits show that wavelet transform has higher fault detection sensitivity than Fourier or time-domain methods and hence, can be considered very promising for defect oriented testing of analog circuits. Effectiveness of wavelet transform based DOT amidst process variation and measurement noise is studied.\",\n \"Title: A Novel Delay Fault Testing Methodology Using Low-Overhead Built-In Delay Sensor\\nYear: 2006\\n\\nAbstract: A novel integrated approach for delay-fault testing in external (automatic-test-equipment-based) and test-per-scan built-in self-test (BIST) using on-die delay sensing and test point insertion is proposed. A robust, low-overhead, and process-tolerant on-chip delay-sensing circuit is designed for this purpose. An algorithm is also developed to judiciously insert delay-sensor circuits at the internal nodes of logic blocks for improving delay-fault coverage with little or no impact on the critical-path delay. The proposed delay-fault testing approach is verified for transition- and segment-delay-fault models. Experimental results for external testing (BIST) show up to 31% (30%) improvement in fault coverage and up to 67.5% (85.5%) reduction in test length for transition faults. An increase in the number of robustly detectable critical-path segments of up to 54% and a reduction in test length for the segment-delay-fault model of up to 76% were also observed. The delay and area overhead due to insertion of the delay-sensing hardware have been limited to 2% and 4%, respectively\",\n \"Title: PETE: A device/circuit analysis framework for evaluation and comparison of charge based emerging devices\\nYear: 2009\\n\\nAbstract: This paper describes PETE, a tool that has been developed for circuit/system level evaluation of nanoscaled devices. The motivation behind developing this tool is the fact that traditional device metrics like CV/Ion, Ioff or CV2f can no longer capture the true potential of semiconductor devices and underestimate or overestimate system level performance. At the same time, the development and deployment of compact models for any new device is a time-consuming effort, a task that can only be undertaken once the potential of the de established. Towards this end, we have developed PETE, so that device and circuit designers can perform a fast and reasonably accurate estimation of any new device without having to develop compact models. The inputs to PETE can be numerical I-V and C-V characteristics (derived from experiments or device simulations), and the tool can numerically evaluate a wide array of circuit/system level metrics pertaining to performance and power of logic gates, ring oscillators and mega-cells. We have evaluated four emerging device technologies, namely, 15 nm Silicon MOSFET transistors, Multi transistors, Band-to-band-tunneling transistors, and Ferroelectric FETs with PETE and the results obtained are within a 5% level of inaccuracy when compared to a traditional SPICE based approach. PETE has been deployed on the nanoHUB (nanohub.org) for public use, and its simple web interface ensures that even a non-expert in circuits can obtain accurate estimation of performance-power trade new technology.\",\n \"Title: Optimization of burn-in test for many-core processors through adaptive spatiotemporal power migration\\nYear: 2010\\n\\nAbstract: We present adaptive spatiotemporal power migration (ASTPM) for burn-in of many core chips. ASTPM adapts the number of simultaneously stressed cores and dynamically varies their location to prevent thermal runaway, improve test-quality, and optimize burn-in time.\",\n \"Title: Resilient microprocessor design for high performance & energy efficiency\\nYear: 2010\\n\\nAbstract: Conventional microprocessors require a clock frequency (FCLK) guardband to ensure correct functionality during infrequent dynamic operating variations in supply voltage (VCC), temperature, and transistor aging. Consequently, these inflexible designs cannot exploit opportunities for higher performance by increasing FCLK or lower energy by reducing VCC during favorable operating conditions. This presentation describes a 45nm resilient microprocessor with error-detection and recovery circuits to detect and correct timing errors from dynamic variations to mitigate the FCLK guardband, thus enabling higher performance or lower energy as compared to a conventional design. The microprocessor core supports two distinct error-detection designs and two separate error-recovery techniques, allowing a direct comparison of the relative trade-offs. Silicon measurements demonstrate that resilient circuits enable a 41% throughput gain at equal energy or a 22% energy reduction at equal throughput, as compared to a conventional design when executing a benchmark program with a 10% VCC droop. In addition, the resilient circuits guide an adaptive clock controller that tracks recovery cycles and adapts to persistent variations by changing FCLK. The combination of error-detection and recovery circuits with dynamic adaptation allows the microprocessor to adapt to the operating environment to deliver maximum efficiency. The presentation concludes by discussing the opportunity of applying resilient techniques to enhance the dynamic operating range (i.e., high-performance and low-power modes) for microprocessors.\",\n \"Title: Novel Low-Overhead Operand Isolation Techniques For Low-Power Datapath Synthesis\\nYear: 2006\\n\\nAbstract: Power consumption in datapath modules due to redundant switching is an important design concern for high-performance applications. Operand isolation schemes are adopted to reduce redundant switching in datapaths. However, they incur considerable overhead in terms of delay, power, and area. This paper presents novel operand isolation techniques based on supply gating that reduce the overheads associated with isolating circuitry. The proposed schemes also target leakage minimization and application of operand isolation at the internal logic of datapath to further reduce power consumption. We integrate the proposed techniques and power/delay models to develop a complete flow for low-power datapath synthesis. Simulation results show that the proposed operand isolation techniques can achieve at least 40% reduction in power consumption compared to the original circuit with minimal area overhead (5%) and small delay penalty (0.15%).\",\n \"Title: Tunable Replica Bits for Dynamic Variation Tolerance in 8T SRAM Arrays\\nYear: 2011\\n\\nAbstract: Infrequent dynamic events like VCC droops and temperature changes result in the use of a static VCC guardband in 8T SRAM arrays. This paper proposes the use of tunable replica bits (TRBs) as a potential solution to mitigating a part of the VCC guardband. Measured data on a 16 KB 8T array featuring tun able replica bits illustrate 9% reduction of the operating minimum VCC (VMIN) and correspondingly a 7.5% reduction in array power.\",\n \"Title: A Model Study of an All-Digital, Discrete-Time and Embedded Linear Regulator.\\nYear: 2015\\n\\nAbstract: With an increasing number of power-states, finer- grained power management and larger dynamic ranges of digital circuits, the integration of compact, scalable linear-regulators embedded deep within logic blocks has become important. While analog linear-regulators have traditionally been used in digital ICs, the need for digitally implementable designs that can be synthesized and embedded in digital functional units for ultra fine- grained power management has emerged. This paper presents the circuit design and control models of an all-digital, discrete-time linear regulator and explores the parametric design space for transient response time and loop stability.\",\n \"Title: The role of adaptation and resiliency in computation and power management\\nYear: 2014\\n\\nAbstract: Variations, both static and dynamic in nature, impact the performance and power-efficiency of microprocessors and other digital integrated circuits. While static process variations can often be mitigated through binning or by post-silicon tuning, dynamic variations change as a function of time and environment and cannot be reduced by static tuning. Examples of these types of dynamic variations include power supply (VCC) droop, temperature change, and device aging over time. The droop magnitude, frequency and duration depend on the complex interaction of capacitive and inductive parasitics at the board, package, and die levels and change with the workload and current demand [1-3]. VCC droops contain high-frequency (i.e., fast changing) and low-frequency (i.e., slow changing) components and occur locally and/or globally across the die. Temperature variations occur at a relatively slower time scale with local hot spots on the die, depending on environmental and workload conditions as well as the heat-removal capability of the package. Further, transistor aging slowly degrades the drive current over time as a function of gate bias and temperature conditions. Conventional designs build in VCC guardband (VCC GB) at a target frequency to ensure correct functionality even in the presence of worst-case dynamic variations. In the digital core, this GB accounts for the delay increase on critical paths when dynamic variations occur and guarantees that timing constraints are met even under worst-case conditions. In the storage arrays (register files and caches) this GB is added to the static minimum operating voltage (VMIN) to obtain the resultant operating VMIN and results in an increase of both leakage and dynamic array power. The key design aspect of adaptive and resilient designs is to remove a part of this GB, such that logic timing and memory functionality can be met at a lower VCC. This improves energy efficiency and improves battery life; a key consideration in mobile and handheld platforms. The mitigation of the design GB can be achieved in two fundamentally different ways. For dynamic variations with time scales in the order of hundreds of μs to ms (such as temperature variations or transistor aging), a reactive scheme where any functional error is avoided is applicable. For example, embedded temperature sensors can be used to trigger changes in the clock frequency or changes in the supply voltage, such that at low temperatures (when transistor currents are higher) a faster clock (at iso-VCC) or a lower supply (at iso-clock frequency) can be employed [4]. For dynamic changes which occur in time scales of ns to μs, such reactive schemes are impossible by design. Hence, an alternative scheme can be employed where timing errors (in logic) or read-write errors (in memory) are allowed to happen. Once errors occur, they are detected, and the errant instruction is replayed with proper care such that data integrity is maintained. A combination of such adaptive schemes (Fig. 1) result in the mitigation of a major part of the design GB, resulting in higher energy efficiency.\",\n \"Title: 5.6 A 0.13μm fully digital low-dropout regulator with adaptive control and reduced dynamic stability for ultra-wide dynamic range\\nYear: 2015\\n\\nAbstract: This paper presents a discrete-time, fully digital, scan-programmable LDO macro in 0.13μm technology featuring greater than 90% current efficiency across a 50× current range, and 8× improvement in transient response time in response to large load steps. The baseline design features a 128b barrel shifter that digitally controls 128 identical power PMOS devices to provide load and line regulation at the node VREG, for a scan-programmable fine-grained synthetic load. A clocked comparator, which eliminates the need for any bias current, controls the direction of shift, D. The programmable mux-select signals, MUX1 and MUX2, provide controllable closed loop gains, KBARREL, of 1 to 3×. Since at any clock edge only 1, 2 or 3 shifts can occur (depending on the gain setting), fine-grained clock gating is enabled by dividing the 128b shifter into four sections and only enabling the clock to the section(s) where the shift occurs.\",\n \"Title: A 32 nm Embedded, Fully-Digital, Phase-Locked Low Dropout Regulator for Fine Grained Power Management in Digital Circuits\\nYear: 2014\\n\\nAbstract: The need for fine-grained power management in digital ICs has led to the design and implementation of compact, scalable low-drop out regulators (LDOs) embedded deep within logic blocks. While analog LDOs have traditionally been used in digital ICs, the need for digitally implementable LDOs embedded in digital functional units for ultrafine grained power management is paramount. This paper presents a fully-digital, phase locked LDO implemented in 32 nm CMOS. The control model of the proposed design has been provided and limits of stability have been shown. Measurement results with a resistive load as well as a digital load exhibit peak current efficiency of 98%.\",\n \"Title: Trim bit setting of analog filters using wavelet-based supply current analysis\\nYear: 2004\\n\\nAbstract: Wavelet transform has the property of resolving signal in both time and frequency unlike Fourier transform. In this work, we show that time-domain information obtained from wavelet analysis of supply current can be used to efficiently trim analog filters. The pole/zero locations in the frequency response of analog filters shift due to change in component values with process variations. Wavelet analysis of supply current can be a promising alternative to test frequency specification of analog filters, since it needs only one test stimulus and is virtually unaffected by transistor threshold variation. Simulation results on two test circuits demonstrate that we can estimate pole/zero shift with less than 3% error.\",\n \"Title: Spin torque devices in embedded memory: Model studies and design space exploration\\nYear: 2013\\n\\nAbstract: Ever larger on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1-3]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin torque transfer (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The minimum size cell (mincell) contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3Fx2F=6F2. In this paper, we examine the design space for key magnetic material properties and access transistor needed for embedded on-die memory with adequate scalability, density, read/write performance and robustness against various intrinsic variabilities and disturbances. New models and simulation methodologies, calibrated to existing measurements [1], for read, write and disturbance mechanisms are developed. Different storage node structures and materials are evaluated to reveal the most promising scaling options.\",\n \"Title: Exploiting Synchronization Properties of Correlated Electron Devices in a Non-Boolean Computing Fabric for Template Matching\\nYear: 2014\\n\\nAbstract: As complementary metal-oxide-semiconductor (CMOS) scaling continues to offer insurmountable challenges, questions about the performance capabilities of Boolean, digital machine based on Von-Neumann architecture, when operated within a power budget, have also surfaced. Research has started in earnest to identify alternative computing paradigms that provide orders of magnitude improvement in power-performance for specific tasks such as graph traversal, image recognition, template matching, and so on. Further, post-CMOS device technologies have emerged that realize computing elements which are neither CMOS replacements nor suited to work as a binary switch. In this paper, we present the realization of coupled and scalable relaxation-oscillators utilizing the metal-insulator-metal transition of vanadium-dioxide (VO2) thin films. We demonstrate the potential use of such a system in a non-Boolean computing paradigm and demonstrate pattern recognition, as one possible application using such a system.\",\n \"Title: Pulsed READ in spin transfer torque (STT) memory bitcell for lower READ disturb\\nYear: 2013\\n\\nAbstract: Large on-die memory arrays for future processors in CMOS logic technology drives the need for dense and scalable embedded memory alternatives beyond SRAM and eDRAM. Recent advances in non-volatile STT-RAM technology, which stores data by the spin orientation of a soft ferromagnetic material and shows current induced switching, have created interest for its use as embedded memory [1-2]. When a spin-polarized current passes through a mono-domain ferromagnet, it attempts to polarize the current in its preferred direction of magnetic moment. As the ferromagnet absorbs some of the angular momentum of the electrons, it creates a torque that causes a flip in the direction of magnetization in the ferromagnet. This is used in magnetic tunneling junction (MTJ) based spin transfer torque (STT) RAM cells where a thin insulator (MgO) is sandwiched between a fixed ferromagnetic layer (polarizer) and the free layer (storage node). This can be integrated in the metal stack (Fig. 1) and hence provide high memory density. Depending on the direction of the current flow (perpendicular to these layers in our study), the magnetization of the free layer is switched to a parallel (P: low resistance state) or anti-parallel (AP: high resistance state) state. The smallest bitcell contains an access transistor (Tx) of width 2F (WTX=2F, F: half-pitch of the process node) and a planar storage node of dimensions 2FxF. The area of the mincell is 3F×2F=6F2 (Fig. 2).\",\n \"Title: An Ultra-low power, “Always-On” Camera Front-End for Posture Detection in Body Worn Cameras using Restricted Boltzman Machines\\nYear: 2015\\n\\nAbstract: The Internet of Things (IoTs) has triggered rapid advances in sensors, surveillance devices, wearables and body area networks with advanced Human-Computer Interfaces (HCI). One such application area is the adoption of Body Worn Cameras (BWCs) by law enforcement officials. The need to be ‘always-on’ puts heavy constraints on battery usage in these camera front-ends, thus limiting their widespread adoption. Further, the increasing number of such cameras is expected to create a data deluge, which requires large processing, transmission and storage capabilities. Instead of continuously capturing and streaming or storing videos, it is prudent to provide “smartness” to the camera front-end. This requires hardware assisted image recognition and template matching in the front-end, capable of making judicious decisions on when to trigger video capture or streaming. Restricted Boltzmann Machines (RBMs) based neural networks have been shown to provide high accuracy for image recognition and are well suited for low power and re-configurable systems. In this paper we propose an RBM based “always-on’’ camera front-end capable of detecting human posture. Aggressive behavior of the human being in the field of view will be used as a wake-up signal for further data collection and classification. The proposed system has been implemented on a Xilinx Virtex 7 XC7VX485T platform. A minimum dynamic power of 19.18 mW for a target recognition accuracy while maintaining real time constraints has been measured. The hardware-software co-design illustrates the trade-offs in the design with respect to accuracy, resource utilization, processing time and power. The results demonstrate the possibility of a true “always-on” body-worn camera system in the IoT environment.\",\n \"Title: The Changing Computing Paradigm With Internet of Things: A Tutorial Introduction.\\nYear: 2016\\n\\nAbstract: This Tutorial paper is about the Internet of Things, its applications, challenges, and how it may change the way of computing. Besides a comprehensive introduction, it focuses on two major design constraints, namely, security and power management.\",\n \"Title: Modeling and Simulation of Vanadium Dioxide Relaxation Oscillators\\nYear: 2015\\n\\nAbstract: This paper deals with modeling and simulation of a new family of two-terminal devices fabricated with vanadium dioxide material. Such devices allow realization of very compact relaxation nano-oscillators that can be connected electronically to form arrays of coupled oscillators. Challenging applications of oscillator arrays include the realization of multiphase signal generators and massively para...\",\n \"Title: Enabling New Computation Paradigms with HyperFET - An Emerging Device.\\nYear: 2016\\n\\nAbstract: High power consumption has significantly increased the cooling cost in high-performance computation stations and limited the operation time in portable systems powered by batteries. Traditional power reduction mechanisms have limited traction in the post-Dennard Scaling landscape. Emerging research on new computation devices and associated architectures has shown three trends with the potential to...\",\n \"Title: Cache Design with Domain Wall Memory.\\nYear: 2016\\n\\nAbstract: Domain wall memory (DWM) is a recently developed spin-based memory technology in which several bits of data are densely packed into the domains of a ferromagnetic wire. DWM has shown great promise in enabling non-volatile memory with very high density and energy efficiency, and has been explored for secondary storage and off-chip memory. In this work, we explore the use of DWM within the on-chip c...\",\n \"Title: Integrated power management in IoT devices under wide dynamic ranges of operation\\nYear: 2015\\n\\nAbstract: By the year 2020 it is expected that corresponding to every human being there would be seven connected devices. These connected devices will usher in the Internet of Things (IoTs) and would percolate every aspect of human life, changing the human experience at a fundamental level. In order to power these devices novel strategies would have to be developed as these devices will not only have a dynamic load, due to multiple features, but also dynamic sources if opportunistic energy harvesting is used to supplement the rechargeable battery. For the power delivery network, figures of merit would be to comprehend both the ability to supply the worst case design as well as to maintain high efficiency across a wide dynamic range. To maintain high efficiency for a large range we will need adaptive components on the load side as well as at the energy source. In this work we will discuss the general IoT power delivery network (PDN), current research and the state of the art PDN components, novel designs and control for interface circuits and energy harvesters.\",\n \"Title: A Model Study of Defects and Faults in Embedded Spin Transfer Torque (STT) MRAM Arrays.\\nYear: 2015\\n\\nAbstract: There has been a significant interest in Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) as a candidate for emerging memory technology for last-level embedded caches in the recent years. High density (3-4x of SRAM), non-volatility, nano-second Read and Write speeds, and process and voltage compatibility with CMOS are the attractive properties of this technology. A few studies have expounded on the reliability in this technology but various fault manifestations have not been studied in detail in the past. This paper attempts to study the fault models in STT-MRAM under both parametric variations as well as electrical defects (opens and shorts). Sensitivity of Read, Write and Retention to material and lithographic process parameters has been studied. Also electrical defects viz. intra-cell and inter-cell opens and shorts have been considered and the corresponding fault models have been identified and classified.\",\n \"Title: A Light-powered, Always-On, Smart Camera with Compressed Domain Gesture Detection.\\nYear: 2016\\n\\nAbstract: In this paper we propose an energy-efficient camera-based gesture recognition system powered by light energy for \\\\\\\"always on\\\\\\\" applications. Low energy consumption is achieved by directly extracting gesture features from the compressed measurements, which are the block averages and the linear combinations of the image sensor's pixel values. The gestures are recognized using a nearest-neighbour (NN) classifier followed by Dynamic Time Warping (DTW). The system has been implemented on an Analog Devices Black Fin ULP vision processor and powered by PV cells whose output is regulated by TI's DC-DC buck converter with Maximum Power Point Tracking (MPPT). Measured data reveals that with only 400 compressed measurements (768x compression ratio) per frame, the system is able to recognize key wake-up gestures with greater than 80% accuracy and only 95mJ of energy per frame. Owing to its fully self-powered operation, the proposed system can find wide applications in \\\\\\\"always-on\\\\\\\" vision systems such as in surveillance, robotics and consumer electronics with touch-less operation.\",\n \"Title: All-digital linear regulators with proactive and reactive gain-boosting for supply droop mitigation in digital load circuits\\nYear: 2016\\n\\nAbstract: This paper explores microarchitecture controlled proactive gain boosting as a means of lowering the effects of supply voltage droop in digital circuits powered by embedded, all-digital linear regulators. A behavioral power supply rejection model for all-digital linear regulator is presented. The presented regulator shows enhanced power supply rejection under increased operating frequency. Test-chip measurements in a 130nm CMOS process reveal more than 2X (4X) reduction in voltage droop (settling time) over purely reactive gain boosting.\",\n \"Title: Vertex Coloring Of Graphs Via Phase Dynamics Of Coupled Oscillatory Networks\\nYear: 2016\\n\\nAbstract: While Boolean logic has been the backbone of digital information processing, there exist classes of computationally hard problems wherein this paradigm is fundamentally inefficient. Vertex coloring of graphs, belonging to the class of combinatorial optimization, represents one such problem. It is well studied for its applications in data sciences, life sciences, social sciences and technology, and hence, motivates alternate, more efficient non-Boolean pathways towards its solution. Here we demonstrate a coupled relaxation oscillator based dynamical system that exploits insulator-metal transition in Vanadium Dioxide (VO2) to efficiently solve vertex coloring of graphs. Pairwise coupled VO2 oscillator circuits have been analyzed before for basic computing operations, but using complex networks of VO2 oscillators, or any other oscillators, for more complex tasks have been challenging in theory as well as in experiments. The proposed VO2 oscillator network harnesses the natural analogue between optimization problems and energy minimization processes in highly parallel, interconnected dynamical systems to approximate optimal coloring of graphs. We further indicate a fundamental connection between spectral properties of linear dynamical systems and spectral algorithms for graph coloring. Our work not only elucidates a physics-based computing approach but also presents tantalizing opportunities for building customized analog co-processors for solving hard problems efficiently.\",\n \"Title: Computing with Dynamical Systems Based on Insulator-Metal-Transition Oscillators.\\nYear: 2016\\n\\nAbstract: In this paper, we review recent work on novel computing paradigms using coupled oscillatory dynamical systems. We explore systems of relaxation oscillators based on linear state transitioning devices, which switch between two discrete states with hysteresis. By harnessing the dynamics of complex, connected systems, we embrace the philosophy of \\\"let physics do the computing\\\" and demonstrate how complex phase and frequency dynamics of such systems can be controlled, programmed, and observed to solve computationally hard problems. Although our discussion in this paper is limited to insulator-to-metallic state transition devices, the general philosophy of such computing paradigms can be translated to other mediums including optical systems. We present the necessary mathematical treatments necessary to understand the time evolution of these systems and demonstrate through recent experimental results the potential of such computational primitives.\",\n \"Title: Analysis of Defects and Variations in Embedded Spin Transfer Torque (STT) MRAM Arrays.\\nYear: 2016\\n\\nAbstract: Spin transfer torque magnetic random access memory (STT-MRAM) is a competitive, future memory technology for last-level embedded caches. It exhibits ultra-high density (3-4X of SRAM), non-volatility, nano-second Read and Write speeds, and process and voltage compatibility with CMOS. As the design and fabrication process mature for the STT-MRAM, there is a need to study the various fault models tha...\",\n \"Title: A 130nm hybrid low dropout regulator based on switched mode control for digital load circuits.\\nYear: 2016\\n\\nAbstract: A hybrid (digital and analog) low dropout regulator (LDO) utilizing switched mode control is designed in 130 nm CMOS for fine grain power management, fast droop recovery and robust small signal regulation of multi-V-CC digital loads. The design provides an optimal trade-off of performance and accuracy by switching between a digital and an analog control loop. The hybrid topology achieves robust small signal regulation and fast recovery from large signal transients or power state transitions. Measurements from a 130nm test-chip show Near-Threshold Voltage (NTV) operation, fast transient response of 18 ns for a load step of 10.3mA and a peak current efficiency of 98.64%.\",\n \"Title: UVFR: A Unified Voltage and Frequency Regulator with 500MHz/0.84V to 100KHz/0.27V operating range, 99.4% current efficiency and 27% supply guardband reduction.\\nYear: 2016\\n\\nAbstract: A fully-digital, single-loop Unified Voltage and Frequency Regulator (UVFR) is designed in 130nm CMOS to provide the correct supply to digital loads to meet a timing criteria. Simultaneously a Tunable Replica Circuit (TRC) based local oscillator is generated from the regulated supply and clocks the load. Measurements show 0.84V to 0.27V range of operation, and 27% supply guardband reduction at iso-performance through adaptation and resiliency which are intrinsic to the control loop.\",\n \"Title: A Sar Pipeline Adc Embedding Time Interleaved Dac Sharing For Ultra-Low Power Camera Front Ends\\nYear: 2015\\n\\nAbstract: The growing need for ultra-low power cameras for sensors, surveillance and consumer applications has resulted in significant advances in compressed domain data acquisition from pixel arrays. In this journal we present a novel 64-input Successive Approximation (SAR) Pipeline analog-to-digital converter (ADC) suitable for compressed domain data acquisition in camera front-ends. The proposed architecture features a time interleaved capacitive digital-to-analog converter (DAC) shared between column parallel ADCs for area savings (2.28X); and a shared amplifier stage for power savings (60%), achieving 4X throughput as compared to traditional architectures. Simulations on a 130nm foundry process shows that the proposed SAR Pipeline ADC draws 31 mu W at 2 MS/s having a target Figure-of-Merit (FOM) of 87 fJ/conv. per step at Nyquist rate. The proposed compressive sensing front end achieves per patch energy per patch of 0.9 nJ.\",\n \"Title: High efficiency power side-channel attack immunity using noise injection in attenuated signature domain\\nYear: 2017\\n\\nAbstract: With the advancement of technology in the last few decades, leading to the widespread availability of miniaturized sensors and internet-connected things (IoT), security of electronic devices has become a top priority. Side-channel attack (SCA) is one of the prominent methods to break the security of an encryption system by exploiting the information leaked from the physical devices. Correlational power attack (CPA) is an efficient power side-channel attack technique, which analyses the correlation between the estimated and measured supply current traces to extract the secret key. The existing countermeasures to the power attacks are mainly based on reducing the SNR of the leaked data, or introducing large overhead using techniques like power balancing. This paper presents an attenuated signature AES (AS-AES), which resists SCA with minimal noise current overhead. AS-AES uses a shunt low-drop-out (LDO) regulator to suppress the AES current signature by 400x in the supply current traces. The shunt LDO has been fabricated and validated in 130 nm CMOS technology. System-level implementation of the AS-AES along with noise injection, shows that the system remains secure even after 50K encryptions, with 10× reduction in power overhead compared to that of noise addition alone.\",\n \"Title: In Quest of the Next Information Processing Substrate: Extended Abstract: Invited.\\nYear: 2017\\n\\nAbstract: Conventional CMOS scaling and the Moore's law have been the cornerstone of progress in computing hardware technology. However, with dimensional scaling expected to end soon, there is a pressing need to find the next information processing hardware that can continue to support the technology revolution. Will this hardware solution be an enhanced or an augmented version of MOSFET or a switch based on a radically new switching mechanism. Ultimately, do we require a complete deviation from the Boolean paradigm itself? In this invited paper, we will review some of the actively pursued future logic, merged logic-memory and related concepts. While it remains unclear which of these options will eventually make it into commercial products, we will argue- based on lessons learnt from the past two decades of transistor development- that sustained and systematic research with careful benchmarking from future workload and applications viewpoint remains the key to success in the quest for the new information processing hardware.\",\n \"Title: Test challenges in embedded STT-MRAM arrays\\nYear: 2017\\n\\nAbstract: Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) is an emerging memory technology which exhibits non-volatility, high density and nanosecond read and write times. These attributes of STT-MRAM make it suitable for last level embedded caches. However, the defects and corresponding fault models of STT-MRAM are not as extensively explored as in SRAM and therefore, there is a growing need for defect and fault analysis. Moreover, stochastic retention failure of STTM-RAM imposes a large burden in testing time. Conventional test schemes for retention of STT-MRAM need to be optimized for testing a large-size embedded STT-MRAM array. This work presents a review of the different defect and fault mechanisms as well as a BIST architecture and circuit to reduce testing time in characterization and manufacturing tests for retention. We address the effect of resistive and capacitive defects and identify retention test setup for measuring worst case retention.\",\n \"Title: Digitally-assisted leakage current supply circuit for reducing the analog LDO minimum dropout voltage\\nYear: 2017\\n\\nAbstract: A digitally-assisted leakage current supply (LCS) circuit reduces the maximum current demand for analog lowdropout (LDO) voltage regulators to lower the minimum dropout voltage (VDO,MIN), and consequently, enable a wider range of LDO operation for power savings in system-on-chip processor cores. From silicon measurements in a 130nm test chip, the LCS assisted hybrid LDO decreases VDO,MIN by 30-38%, resulting in core power reduction of 21-28% at equal clock frequencies within the wider LDO operating range.\",\n \"Title: Self-Optimizing IoT Wireless Video Sensor Node With In-Situ Data Analytics and Context-Driven Energy-Aware Real-Time Adaptation.\\nYear: 2017\\n\\nAbstract: It is well understood that data-acquisition by distributed sensors and subsequent transmission of all the acquired data to the cloud will produce a “data deluge” in next-generation wireless networks leading to immense network congestion, and data back-logs on the server which will prevent real-time processing and control. This motivates in situ data analytics in energy-constrained wireless sensor ...\",\n \"Title: Stochastic IMT (insulator-metal-transition) neurons: An interplay of thermal and threshold noise at bifurcation.\\nYear: 2017\\n\\nAbstract: Artificial neural networks can harness stochasticity in multiple ways to enable a vast class of computationally powerful models. Boltzmann machines and other stochastic neural networks have been shown to outperform their deterministic counterparts by allowing dynamical systems to escape local energy minima. Electronic implementation of such stochastic networks is currently limited to addition of algorithmic noise to digital machines which is inherently inefficient; albeit recent efforts to harness physical noise in devices for stochasticity have shown promise. To succeed in fabricating electronic neuromorphic networks we need experimental evidence of devices with measurable and controllable stochasticity which is complemented with the development of reliable statistical models of such observed stochasticity. Current research literature has sparse evidence of the former and a complete lack of the latter. This motivates the current article where we demonstrate a stochastic neuron using an insulator-metal-transition (IMT) device, based on electrically induced phase-transition, in series with a tunable resistance. We show that an IMT neuron has dynamics similar to a piecewise linear FitzHugh-Nagumo (FHN) neuron and incorporates all characteristics of a spiking neuron in the device phenomena. We experimentally demonstrate spontaneous stochastic spiking along with electrically controllable firing probabilities using Vanadium Dioxide (VO2) based IMT neurons which show a sigmoid-like transfer function. The stochastic spiking is explained by two noise sources - thermal noise and threshold fluctuations, which act as precursors of bifurcation. As such, the IMT neuron is modeled as an Ornstein-Uhlenbeck (OU) process with a fluctuating boundary resulting in transfer curves that closely match experiments. The moments of interspike intervals are calculated analytically by extending the first-passage-time (FPT) models for Ornstein-Uhlenbeck (OU) process to include a fluctuating boundary. We find that the coefficient of variation of interspike intervals depend on the relative proportion of thermal and threshold noise, where threshold noise is the dominant source in the current experimental demonstrations. As one of the first comprehensive studies of a stochastic neuron hardware and its statistical properties, this article would enable efficient implementation of a large class of neuro-mimetic networks and algorithms.\",\n \"Title: Connecting spectral techniques for graph coloring and eigen properties of coupled dynamics: A pathway for solving combinatorial optimizations (Invited paper).\\nYear: 2017\\n\\nAbstract: This paper reviews an analog circuit system of capacitively coupled relaxation oscillators whose time evolution can be used to solve the graph coloring problem. These oscillators consist of a series combination of an insulator-metal-transition (IMT) device and a resistance. Such circuits were also demonstrated experimentally using VO 2 (Vanadium Dioxide) as the phase transition material. The time evolution of circuit dynamics depend on eigenvectors of the adjacency matrix in the same way as is used by spectral algorithms for graph coloring. As such, a coupled network of such oscillators with piecewise linear dynamics have steady state phases which can be used to approximate the minimum vertex coloring of a graph.\",\n \"Title: A 65nm 376nA 0.4V linear classifier using time-based matrix-multiplying ADC with non-linearity aware training\\nYear: 2017\\n\\nAbstract: A 6-bit time-based folding matrix multiplication technique for support vector machine (SVM) classification is proposed. A voltage controlled oscillator (VCO) based analog-to-digital converter (ADC) performs in-situ matrix multiplications (MM) along with analog to digital conversion. It also offers a low supply voltage of operation (down to 0.4V) and an input range of 0.8V, drawing a total of 376nA of current. We propose a technique to extend the input range of the VCO based ADC using a folding technique. The classifier is trained considering the non-linearity of the VCO, which results in 5X lower power at iso-accuracy. An accuracy of 93% is achieved with adaboost at the digital back-end with linear SVM as the weak classifier.\",\n \"Title: Modeling and Analysis of Magnetic Field Induced Coupling on Embedded STT-MRAM Arrays.\\nYear: 2018\\n\\nAbstract: Spin transfer torque magnetic random access memory (STT-MRAM) is an emerging memory technology which exhibits nonvolatility, high density, high endurance, and nano-second read and write times. These characteristics make STT-MRAM suitable for last-level cache and other embedded applications. The STT-MRAM bit-cell consists of a magnetic tunnel junction (MTJ) which is composed of two ferromagnetic la...\",\n \"Title: Switched-Mode-Control Based Hybrid LDO for Fine-Grain Power Management of Digital Load Circuits.\\nYear: 2018\\n\\nAbstract: Switched-mode-control (SMC) is a control methodology that allows instantaneous switching between controllers to extend the dynamic range of feedback circuits. A hybrid low dropout voltage regulator utilizing SMC is designed in 130 nm CMOS for fine-grain power management, fast droop recovery, and accurate voltage regulation of digital load circuits. The design provides an optimal tradeoff between p...\",\n \"Title: A 130 nm 165 nJ/frame Compressed-Domain Smashed-Filter-Based Mixed-Signal Classifier for \\\"In-Sensor\\\" Analytics in Smart Cameras.\\nYear: 2018\\n\\nAbstract: To avoid data deluge at the back end, it is imperative that advanced sensor nodes perform “in-sensor” processing to extract relevant features from data. We propose a compressed-domain smashed-filter-based object recognition system and measurements from a 130 nm mixed-signal test chip to demonstrate reconfigurable and ultra-low power operation. We measure greater than 90% accuracy in object localiz...\",\n \"Title: A 65nm compressive-sensing time-based ADC with embedded classification and INL-aware training for arrhythmia detection.\\nYear: 2017\\n\\nAbstract: In-sensor analytics are in high demand to avoid high computation at server back end. Traditional analog sensors require high supply voltage in the range of 1–1.2V even when digital supplies are scaled down to 0.4V-0.6V. We propose a time-based compressed-domain analog-to-digital (ADC) based encoder with parallel processing units for arrhythmia classification. The computationally enhanced ADC performs in-situ compression along with analog to digital conversion. An accuracy of 84% accuracy is achieved with 10.5nJ energy per classification for an 8X compression ratio.\",\n \"Title: Smart Sensing for HVAC Control: Collaborative Intelligence in Optical and IR Cameras.\\nYear: 2018\\n\\nAbstract: Energy management of heating, ventilation, and cooling (HVAC) has become a primary concern for residential and commercial buildings. In order to save energy without compromising the comfort of occupants, various techniques have been explored to sense the real-time occupancy/vacancy of HVAC zones. Among all these approaches, wireless-camera-based sensing stands out for its potential application in ...\",\n \"Title: NavREn-Rl: Learning to fly in real environment via end-to-end deep reinforcement learning using monocular images\\nYear: 2018\\n\\nAbstract: We present NavREn-RL, an approach to NAVigate an unmanned aerial vehicle in an indoor Real ENvironment via end-to-end reinforcement learning (RL). A suitable reward function is designed keeping in mind the cost and weight constraints for micro drone with minimum number of sensing modalities. Collection of small number of expert data and knowledge based data aggregation is integrated into the RL process to aid convergence. Experimentation is carried out on a Parrot AR drone in different indoor arenas and the results are compared with other baseline technologies. We demonstrate how the drone successfully avoids obstacles and navigates across different arenas. Video of the drone navigating using the proposed approach can be seen at https://youtu.be/yOTkTHUPNVY.\",\n \"Title: Computing with Coupled Oscillators: Theory, Devices, and Applications\\nYear: 2018\\n\\nAbstract: This paper will give a review of recent work on using networks of coupled oscillators for analog information processing. We will discuss the rationale of using coupled oscillators, and how they can be used to perform computational tasks, such as associative computing primitives, or how they can serve as hardware accelerators in vision processing pipelines. Further, we will study two specific physical implementations for such oscillator, namely relaxation oscillators based on metal-insulator phase transitions and magnetic spin-torque oscillators. We will also discuss the potential of such coupled-oscillator networks to solve computationally-hard optimization problems or even NP-hard problems.\",\n \"Title: A Light-Powered Smart Camera With Compressed Domain Gesture Detection.\\nYear: 2018\\n\\nAbstract: This paper presents an ultralow power smart camera with gesture detection. Low power is achieved by directly extracting gesture features from the compressed measurements, which are the block averages and the linear combinations of the image sensor's pixel values. We present two classifier techniques to allow low computational and storage requirements. The system has been implemented on an analog d...\",\n \"Title: A Reconfigurable Hybrid Low Dropout Voltage Regulator for Wide-Range Power Supply Noise Rejection and Energy-Efficiency Trade-Off.\\nYear: 2018\\n\\nAbstract: A scan-reconfigurable hybrid low dropout (LDO) macro with four operating modes to support tuning across a wide range of power supply noise rejection and power efficiency is presented. The configurations include: 1) a full-digital LDO; 2) an analog loop in parallel with a digital loop in switched mode control; 3) an analog LDO in parallel with discrete current sources; and 4) discrete current sourc...\",\n \"Title: Dynamics of Coupled Systems and their Computing Properties Invited Paper : Invited Paper\\nYear: 2018\\n\\nAbstract: Collective dynamical systems offer unique opportunities for computing by harnessing the complex interactions of simple elements such as oscillators or spike generators. This is possible when such dynamics can be programmed, controlled, and observed. In this talk, we will present some of our work where we are exploring the time-evolution of both deterministic and stochastic dynamical systems in both CMOS and post-CMOS computing substrates. Such systems find applications in solving inverse problems, distributed optimizations (convex and combinatorial) and machine learning. In this paper we will discuss our recent work that connects dynamics and algebraic graph theory. We will talk about implementation of such dynamics in mixed-signal CMOS, including a recent demonstration of reinforcement learning for energy-constrained edge devices. We will conclude with a brief discussion of the opportunities, potentials and challenges in realizing such computational systems.\",\n \"Title: A 55-nm, 1.0–0.4V, 1.25-pJ/MAC Time-Domain Mixed-Signal Neuromorphic Accelerator With Stochastic Synapses for Reinforcement Learning in Autonomous Mobile Robots\\nYear: 2019\\n\\nAbstract: Reinforcement learning (RL) is a bio-mimetic learning approach, where agents can learn about an environment by performing specific tasks without any human supervision. RL is inspired by behavioral psychology, where agents take actions to maximize a cumulative reward. In this paper, we present an RL neuromorphic accelerator capable of performing obstacle avoidance in a mobile robot at the edge of the cloud. We propose an energy-efficient time-domain mixed-signal (TD-MS) computational framework. In TD-MS computation, we demonstrate that the energy to compute is proportional to the importance of the computation. We leverage the unique properties of stochastic networks and recent advances in Q-learning in the proposed RL implementation. The 55-nm test chip implements RL using a three-layered fully connected neural network and consumes a peak power of 690 \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\mu \\\\text{W}$ </tex-math></inline-formula>\\n.\",\n \"Title: Computing With Networks of Oscillatory Dynamical Systems.\\nYear: 2019\\n\\nAbstract: As we approach the end of the silicon road map, alternative computing models that can solve at-scale problems in the data-centric world are becoming important. This is accompanied by the realization that binary abstraction and Boolean logic, which have been the foundations of modern computing revolution, fall short of the desired performance and power efficiency. In particular, hard computing prob...\",\n \"Title: 14.1 A 65nm 1.1-to-9.1TOPS/W Hybrid-Digital-Mixed-Signal Computing Platform for Accelerating Model-Based and Model-Free Swarm Robotics\\nYear: 2019\\n\\nAbstract: Artificial swarm intelligence, inspired by biological studies of insects, ants and other organisms, present an emerging computing paradigm, where seemingly simple elements interact with each other to collectively solve challenging problems. In particular, swarm robotics, where multiple robots co-ordinate in real-time to solve diverse problems such as pattern-formation, cooperative reinforcement learning (RL), path-planning etc. [1], find extensive uses in exploration, reconnaissance and disaster relief. This is partly motivated by the robustness of swarm dynamics to failures and malfunctions of individual robots. Successful hardware demonstrations of neuro-inspired algorithms on edge-devices [2]–[6] is now leading to the emergence of intelligence and control in swarms as the next frontier. Although certain swarm algorithms rely on real-time learning (e.g., cooperative RL) representing a model-free approach, many powerful algorithms that have been developed over the past two decades (e.g., pattern formation) rely on a mathematical structure and represent a more traditional model-based approach. The next generation of swarm hardware needs to support both of these approaches. In this paper, we identify the commonalities and shared compute primitives across a variety of model-based and model-free swarm algorithms and present a unified, fully-programmable, energy-efficient and scalable platform capable of real-time swarm intelligence.\",\n \"Title: Test and Reliability of Emerging Non-volatile Memories\\nYear: 2017\\n\\nAbstract: The search for alternative memory technologies has attracted significant attention toward emerging non-volatile memories. Among them, STT-MRAM, PCM, RRAM have shown promising characteristic to gain a position inside the memory hierarchy of computing platforms, and even enable new computing paradigms. However like any other emerging technology these devices are affected by concerns to be resolved before they could become a mainstream. This paper reviews the main reliability and testability challenges of aforementioned emerging non-volatile memories and highlights the main future considerations toward them.\",\n \"Title: ASNI: Attenuated Signature Noise Injection for Low-Overhead Power Side-Channel Attack Immunity.\\nYear: 2018\\n\\nAbstract: Computationally-secure cryptographic algorithms implemented on a physical platform leak significant “side-channel” information through their power supplies. Correlational power attack is an efficient power side-channel attack (SCA) technique, which analyzes the statistical correlation between the estimated and the measured supply current traces to extract the secret key. The existing power SCA cou...\",\n \"Title: A FeFET Based Processing-In-Memory Architecture for Solving Distributed Least-Square Optimizations\\nYear: 2018\\n\\nAbstract: HfO\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n based ferroelectric FET (FeFET) has recently received great interest for its application in nonvolatile memory (NVM) [1]. Unlike conventional perovskite based ferroelectric materials, HfO\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n is CMOS compatible and retains ferroelectricity for thin film with thickness around 10 nm. Therefore, successful integration of ferroelectric HfO\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n into advanced CMOS technology makes this technology highly promising for NVM [1]. Moreover, by tuning the portion of switched ferroelectric domain, a FeFET can exhibit multiple intermediate states, which enables its application as an analog conductance in mixed-signal in-memory computing. Currently, such architectures have been applied to neuromorphic computing [2], [3]. In this paper, we present a processing-in-memory (PIM) architecture with FeFETs and demonstrate how this can be used to solve a new class of optimization problems, in particular, distributed least square minimization.\",\n \"Title: Context-Aware Intelligence in Resource-Constrained IoT Nodes: Opportunities and Challenges.\\nYear: 2019\\n\\nAbstract: Editor's note: This article provides an academic perspective of the problem, starting with a survey of recent advances in intelligent sensing, computation, communication, and energy management for resource-constrained IoT sensor nodes and leading to a future outlook and needs. -Shreyas Sen, Purdue University.\",\n \"Title: Guest Editors' Introduction: Intelligent Resource-Constrained Sensor Nodes.\\nYear: 2019\\n\\nAbstract: Following continued system miniaturization for over past five decades, the size of unit computing has been steadily shrinking. In the foreseeable future, computing will be all around us, in mostly invisible forms, and is expected to lead more than 50 billion Internet-of-Things (IoT) devices, at the forefront of which will be distributed sensing nodes acting as the eyes and ears of IoT.\",\n \"Title: Transfer And Online Reinforcement Learning In Stt-Mram Based Embedded Systems For Autonomous Drones\\nYear: 2019\\n\\nAbstract: In this paper we present an algorithm-hardware co design for camera-based autonomous flight in small drones. We show that the large write-latency and write-energy for nonvolatile memory (NVM) based embedded systems makes them unsuitable for real-time reinforcement learning (RL), We address this by performing transfer learning (TL) on meta environments and RL on the last few layers of a deep convolutional network. While the NVM stores the meta-model from TL, an on-die SRAM stores the weights of the last few layers. Thus all the real-time updates sia RL are carried out on the SRAM arrays. This provides us with a practical platform with comparable performance as end-to-end RL and 83.4% lower energy per image frame.\",\n \"Title: X-DeepSCA: Cross-Device Deep Learning Side Channel Attack\\nYear: 2019\\n\\nAbstract: This article, for the first time, demonstrates Cross-device Deep Learning Side-Channel Attack (X-DeepSCA), achieving an accuracy of > 99.9%, even in presence of significantly higher inter-device variations compared to the inter-key variations. Augmenting traces captured from multiple devices for training and with proper choice of hyper-parameters, the proposed 256-class Deep Neural Network (DNN) learns accurately from the power side-channel leakage of an AES-128 target encryption engine, and an N-trace (N ≤ 10) X-DeepSCA attack breaks different target devices within seconds compared to a few minutes for a correlational power analysis (CPA) attack, thereby increasing the threat surface for embedded devices significantly. Even for low SNR scenarios, the proposed X-DeepSCA attack achieves ~ 10× lower minimum traces to disclosure (MTD) compared to a traditional CPA.\",\n \"Title: Direct Feedback Alignment with Sparse Connections for Local Learning.\\nYear: 2019\\n\\nAbstract: Recent advances in deep neural networks (DNNs) owe their success to training algorithms that use backpropagation and gradient-descent. Backpropagation, while highly effective on von Neumann architectures, becomes inefficient when scaling to large networks. Commonly referred to as the weight transport problem, each neuron's dependence on the weights and errors located deeper in the network require exhaustive data movement which presents a key problem in enhancing the performance and energy-efficiency of machine-learning hardware. In this work, we propose a bio-plausible alternative to backpropagation drawing from advances in feedback alignment algorithms in which the error computation at a single synapse reduces to the product of three scalar values. Using a sparse feedback matrix, we show that a neuron needs only a fraction of the information previously used by the feedback alignment algorithms. Consequently, memory and compute can be partitioned and distributed whichever way produces the most efficient forward pass so long as a single error can be delivered to each neuron. We evaluate our algorithm using standard datasets, including ImageNet, to address the concern of scaling to challenging problems. Our results show orders of magnitude improvement in data movement and 2x improvement in multiply-and-accumulate operations over backpropagation. Like previous work, we observe that any variant of feedback alignment suffers significant losses in classification accuracy on deep convolutional neural networks. By transferring trained convolutional layers and training the fully connected layers using direct feedback alignment, we demonstrate that direct feedback alignment can obtain results competitive with backpropagation. Furthermore, we observe that using an extremely sparse feedback matrix, rather than a dense one, results in a small accuracy drop while yielding hardware advantages. All the code and results are available under https://github.com/bcrafton/ssdfa.\",\n \"Title: Efficient Signal Reconstruction Via Distributed Least Square Optimization On A Systolic Fpga Architecture\\nYear: 2019\\n\\nAbstract: Optimization problems form the basis of a wide gamut of computationally challenging tasks in signal processing, machine learning, resource planning and so on. Out of these, convex optimization, and in particular least square optimization, covers a vast majority; and recent advances in iterative algorithms to solve such problems of large dimensions have gained traction. Multi-core designs with systolic or semisystolic architectures can be a key enabler for implementing discrete dynamical systems and realize massively scalable architectures to solve such optimization algorithms. In this paper, we present a platform architecture implemented in programmable FPGA hardware to solve a template problem in distributed optimization, namely signal reconstruction from non-uniform sampling. This is a quintessential problem with wide-spread applications in signal processing, computational imaging etc. We expect such an architectural exploration to open up promising opportunities to solve distributed optimizations that are becoming increasingly important in real-world applications. The complete system design, mapping and optimization into an FPGA architecture as well as analysis of convergence and scalability have been presented.\",\n \"Title: Statistical optimization of compute in-memory performance under device variation\\nYear: 2021\\n\\nAbstract: ABSTRACTCompute in-memory (CIM) is a promising technique that minimizes data transport, maximizes memory throughput, and performs computation on the bitline of memory sub-arrays. Utilizing embedded non-volatile memories (eNVM) such as resistive random access memory (RRAM), various forms of neural networks can be implemented. Unfortunately, CIM faces new challenges traditional CMOS architectures have avoided. In this work, we explore the impact of device variation (calibrated with measured data on foundry RRAM arrays) and propose a new algorithm based on device variation to increase both performance and accuracy for CIM designs. We demonstrate up to 36% power improvement and 44% performance improvement, while satisfying any error constraint.\",\n \"Title: Hardware-Algorithm Co-Design Enabling Efficient Event-based Object Detection\\nYear: 2021\\n\\nAbstract: Event-based cameras are a promising alternative to traditional optical cameras for real time computer vision systems. They offer low power, high temporal resolution, and high dynamic range, making them an ideal candidate for resource-constrained edge computing. In this work, we evaluate system level designs using event-based cameras for computer vision on the edge. We present a new technique to im...\",\n \"Title: RAPID-RL: A Reconfigurable Architecture with Preemptive-Exits for Efficient Deep-Reinforcement Learning\\nYear: 2022\\n\\nAbstract: Present-day Deep Reinforcement Learning (RL) systems show great promise towards building intelligent agents surpassing human-level performance. However, the computational complexity associated with the underlying deep neural networks (DNNs) leads to power-hungry implementations. This makes deep RL systems unsuitable for deployment on resource-constrained edge devices. To address this challenge, we propose a reconfigurable architecture with preemptive exits for effi-cient deep RL (RAPID-RL). RAPID-RL enables conditional activation of DNN layers based on the difficulty level of inputs. This allows to dynamically adjust the compute effort during inference while maintaining competitive performance. We achieve this by augmenting a deep Q-network (DQN) with side-branches capable of generating intermediate predictions along with an associated confidence score. We also propose a novel training methodology for learning the actions and branch confidence scores in a dynamic RL setting. Our experiments evaluate the proposed framework for Atari 2600 gaming tasks and a realistic Drone navigation task on an open-source drone simulator (PEDRA). We show that RAPID-RL incurs 0.34 × (0.25 ×) number of operations (OPS) while maintaining performance above 0.88 × (0.91 ×) on Atari (Drone navigation) tasks, compared to a baseline-DQN without any side-branches. The reduction in OPS leads to fast and efficient inference, proving to be highly beneficial for the resource-constrained edge where making quick decisions with minimal compute is essential.\",\n \"Title: Analyzing and Improving Fault Tolerance of Learning-Based Navigation Systems\\nYear: 2021\\n\\nAbstract: Learning-based navigation systems are widely used in autonomous applications, such as robotics, unmanned vehicles and drones. Specialized hardware accelerators have been proposed for high-performance and energy-efficiency for such navigational tasks. However, transient and permanent faults are increasing in hardware systems and can catastrophically violate tasks safety. Meanwhile, traditional redundancy-based protection methods are challenging to deploy on resource-constrained edge applications. In this paper, we experimentally evaluate the resilience of navigation systems with respect to algorithms, fault models and data types from both RL training and inference. We further propose two efficient fault mitigation techniques that achieve 2x success rate and 39% quality-of-flight improvement in learning-based navigation systems.\",\n \"Title: A 40-nm, 64-Kb, 56.67 TOPS/W Voltage-Sensing Computing-In-Memory/Digital RRAM Macro Supporting Iterative Write With Verification and Online Read-Disturb Detection\\nYear: 2022\\n\\nAbstract: Computing-in-memory (CIM) architectures have gained importance in achieving high-throughput energy-efficient artificial intelligence (AI) systems. Resistive RAM (RRAM) is a promising candidate for CIM architectures due to a multiply-and-accumulate (MAC)-friendly structure, high bit density, compatibility with a CMOS process, and nonvolatility. Notwithstanding the advancement of RRAM technology, th...\",\n \"Title: A decentralized policy gradient approach to multi-task reinforcement learning.\\nYear: 2021\\n\\nAbstract: We develop a mathematical framework for solving multi-task reinforcement learning (MTRL) problems based on a type of policy gradient method. The goal in MTRL is to learn a common policy that operates effectively in different environments; these environments have similar (or overlapping) state spaces, but have different rewards and dynamics. We highlight two fundamental challenges in MTRL that are not present in its single task counterpart, and illustrate them with simple examples. We then develop a decentralized entropyregularized policy gradient method for solving the MTRL problem, and study its finite-time convergence rate. We demonstrate the effectiveness of the proposed method using a series of numerical experiments. These experiments range from small-scale \\\"GridWorld\\\" problems that readily demonstrate the trade-offs involved in multi-task learning to large-scale problems, where common policies are learned to navigate an airborne drone in multiple (simulated) environments.\",\n \"Title: An Energy-Efficient and Runtime-Reconfigurable FPGA-Based Accelerator for Robotic Localization Systems\\nYear: 2022\\n\\nAbstract: A robot usually localizes itself in an environment by estimating the collection of its position and rotation states, while constructing a map of unknown surroundings, giving rise to the notion of Simultaneous Localization and Mapping (SLAM). SLAM is a fundamental kernel in autonomous machines at all computing scales, from drones, AR, VR to self-driving cars. Principled mathematical solutions for SLAM involve filtering-based or non-linear optimization-based (Fig. 1a), where the latter recently shows higher robustness but with intensive computation. Prior ASICs [1], [2] and FPGAs [3], [4], [5] have accelerated SLAM on hardware, but they usually target one specific design. In this work, we present a runtime-reconfigurable FPGA accelerator for robotic localization tasks. We exploit SLAM-specific data locality, sparsity, reuse, and parallelism, and achieve >5x performance improvement over the state-of-the-art. Especially, our design is reconfigurable at runtime according to the environment and platform to save power while sustaining accuracy and performance.\",\n \"Title: FRL-FI: Transient Fault Analysis for Federated Reinforcement Learning-Based Navigation Systems\\nYear: 2022\\n\\nAbstract: Swarm intelligence is being increasingly deployed in autonomous systems, such as drones and unmanned vehicles. Federated reinforcement learning (FRL), a key swarm intelligence paradigm where agents interact with their own environments and cooperatively learn a consensus policy while preserving privacy, has recently shown potential advantages and gained popularity. However, transient faults are increasing in the hardware system with continuous technology node scaling and can pose threats to FRL systems. Meanwhile, conventional redundancy-based protection methods are challenging to deploy on resource-constrained edge applications. In this paper, we experimentally evaluate the fault tolerance of FRL navigation systems at various scales with respect to fault models, fault locations, learning algorithms, layer types, communication intervals, and data types at both training and inference stages. We further propose two cost-effective fault detection and recovery techniques that can achieve up to \\n<tex xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">$3.3\\\\times$</tex>\\n improvement in resilience with \\n<tex xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">$<2.7\\\\%$</tex>\\n overhead in FRL systems.\",\n \"Title: Robotic Computing on FPGAs: Current Progress, Research Challenges, and Opportunities\\nYear: 2022\\n\\nAbstract: Robotic computing has reached a tipping point, with a myriad of robots (e.g., drones, self-driving cars, logistic robots) being widely applied in diverse scenarios. The continuous proliferation of robotics, however, critically depends on efficient computing substrates, driven by real-time requirements, robotic size-weight-and-power constraints, cybersecurity considerations, and dynamically changing scenarios. Within all platforms, FPGA is able to deliver both software and hardware solutions with low power, high performance, reconfigurability, reliability, and adaptivity characteristics, serving as the promising computing substrate for robotic applications. This paper highlights the current progress, design techniques, challenges, and open research challenges in the domain of robotic computing on FPGAs.\",\n \"Title: A Practical Design-Space Analysis of Compute-in-Memory With SRAM\\nYear: 2022\\n\\nAbstract: Analog-domain compute-in-memory (CIM) is a technique that has emerged in part as a response to the memory-intensive vector-matrix-multiplications (VMMs) required to implement important emerging applications, notably machine learning inference. Implemented CIM systems have demonstrated good energy efficiency for lower-precision systems and/or with loosened compute-level accuracy requirements. A ...\",\n \"Title: BitS-Net: Bit-Sparse Deep Neural Network for Energy-Efficient RRAM-Based Compute-In-Memory\\nYear: 2022\\n\\nAbstract: The rising popularity of intelligent mobile devices and the computational cost of deep learning-based models call for efficient and accurate on-device inference schemes. We propose a novel model compression scheme that allows inference to be carried out using bit-level sparsity, which can be efficiently implemented using in-memory computing macros. In this paper, we introduce a method called BitS-Net to leverage the benefits of bit-sparsity (where the number of zeros are more than number of ones in binary representation of weight/activation values) when applied to compute-in-memory (CIM) with resistive RAM (RRAM) to develop energy efficient DNN accelerators operating in the inference mode. We demonstrate that BitS-Net improves the energy efficiency by up to 5x for ResNet models on the ImageNet dataset.\",\n \"Title: A 65 nm Wireless Image SoC Supporting On-Chip DNN Optimization and Real-Time Computation-Communication Trade-Off via Actor-Critical Neuro-Controller\\nYear: 2022\\n\\nAbstract: The widespread proliferation of smart sensors has led to hardware that enable edge intelligence (EI) with extreme energy efficiencies. This decreases the volume of data that is transmitted to the cloud, thus reducing: 1) processing latency; 2) communication energy; and 3) network congestion. However, this comes with an added cost of computation at the edge node. The cost (energy/latency) of edge computation and the cost of communication to the cloud vary widely depending on operating conditions, which include: 1) information content in the data; 2) algorithm selection; 3) channel conditions (noise, path-loss, etc.); 4) network size, available bandwidth; and 5) resources at the cloud. This article presents a 65 nm wireless image processing SoC for real-time computation-communication trade-off on resource-constrained edge devices. The test-chip includes: 1) an all-digital, near-memory, reconfigurable, and programmable neural-network (NN)-based systolic image processor; 2) a digitally adaptive radio-frequency digital-to-analog converter (RF-DAC)-based transceiver; and 3) a mixed-signal, time-based, actor-critic (AC) neuro-controller with compute-in-memory (CIM) and in-place weight updates that provide online learning and adaptation for efficiently controlling the computation, communication blocks separately as well as jointly. The major contributions of the proposed SoC are threefold: 1) a wireless Internet of Things (IoT) SoC architecture enabling a generic computation-communication trade-off scheme; 2) a novel CIM circuit design enabling effective AC control and online learning (0.59 pJ/MAC, 0.4 pJ/update); 3) integration of programmable deep NN (DNN) accelerator (1.05 TOPS/W) and reconfigurable transceiver (184 pJ/b @ –15 dBm) supporting versatile cloud-edge collaborations; and 4) significant system-level energy efficiency improvement (5.7\\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\times $ </tex-math></inline-formula>\\n) with real-time on-chip smart control enabled by seamless chip integration and AI-enabled decision-making. Furthermore, this SoC serves as a system-level IoT prototype for next-generation context-aware EI.\",\n \"Title: An End-to-End Spiking Neural Network Platform for Edge Robotics: From Event-Cameras to Central Pattern Generation\\nYear: 2022\\n\\nAbstract: Learning to adapt one’s gait with environmental changes plays an essential role in the locomotion of legged robots which remains challenging for constrained computing resources and energy budget, as in the case of edge-robots. Recent advances in bio-inspired vision with dynamic vision sensors (DVSs) and associated neuromorphic processing can provide promising solutions for end-to-end sensing, cognition, and control tasks. However, such bio-mimetic closed-loop robotic systems based on event-based visual sensing and actuation in the form of spiking neural networks (SNNs) have not been well explored. In this work, we program the weights of a bio-mimetic multigait central pattern generator (CPG) and couple it with DVS-based visual data processing to show a spike-only closed-loop robotic system for a prey-tracking scenario. We first propose a supervised learning rule based on stochastic weight updates to produce a multigait producing spiking-CPG (SCPG) for hexapod robot locomotion. We then actuate the SCPG to seamlessly transition between the gaits for a nearest prey tracking task by incorporating SNN-based visual processing for input event-data generated by the DVS. This for the first time, demonstrates the natural coupling of event data flow from event-camera through SNN and neuromorphic locomotion. Thus, we exploit bio-mimetic dynamics and energy advantages of spike-based processing for autonomous edge-robotics.\",\n \"Title: A 90.4% Peak Efficiency 48V/1V Three-Level Hybrid Dickson Converter with Gradient Descent Run-Time Optimizer and GaN/Si Hybrid Conversion\\nYear: 2022\\n\\nAbstract: This work presents a 48V/1V DC-DC Point-of-Load (POL) converter for efficient high voltage conversion in data centers. The converter includes (1) a three-level hybrid Dickson topology with GaN/Si hybrid conversion achieving efficient flying capacitor (C\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">F</inf>\\n) utilization. (2) A gradient descent run-time optimizer finding optimal switching frequency (f\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">SW</inf>\\n) and number of fingers turned on (N\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">F</inf>\\n) during converter’s operation. (3) A 10bit hybrid ADC for current sensing. The test chip is fabricated in 0.18μm BCD process and shows a 90.4% peak efficiency at 48V-1V conversion with a 240 A/inch\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">3</sup>\\n current density.\",\n \"Title: A low power and PVT variation tolerant mux-latch for serializer interface and on-chip serial link\\nYear: 2022\\n\\nAbstract: Multiplexer (mux) latch is one of the key components for serializer interface to admit communication at Gbps. This work describes the working of a 2:1 mux-latch coupled to a power delivery network (PDN) and a CPU core drawing abrupt current. In comparison to conventional designs, multiplexer and latch operate at the same time, which is quite different because enable inputs are imperative to start latch operation. An analytical model is also derived to understand power delay trade-off and to choose gate sizes to obtain a comparable delay without increasing power. The average power and delay in post-layout are 257.7 μW and 35 ps, respectively, in a 90-nm CMOS, power supply voltage (Vdd) of 1.1 V and a clock switching at 6.25 GHz. However, a 117OC change in temperature at distinct corner allows average power to vary between 32.8 and 64 μW. The corresponding variation is 135–183.7 μW as Vdd switches from 0.75 to 1.1 V. In addition to so, delay changes between 5-14 ps and 3–12 ps for the given change in temperature and Vdd, respectively. Nonetheless, the effective supply voltage VP oscillates with time as the CPU core draws abrupt current. The delay values due to AC noise are found to be different than VP having no noise and the corresponding jitter changes linearly as a function of noise.\",\n \"Title: Gradient Backpropagation based Feature Attribution to Enable Explainable-AI on the Edge\\nYear: 2022\\n\\nAbstract: There has been a recent surge in the field of Explainable AI (XAI) which tackles the problem of providing insights into the behavior of black-box machine learning models. Within this field, feature attribution encompasses methods which assign relevance scores to input features and visualize them as a heatmap. Designing flexible accelerators for multiple such algorithms is challenging since the hardware mapping of these algorithms has not been studied yet. In this work, we first analyze the dataflow of gradient backpropagation based feature attribution algorithms to determine the resource overhead required over inference. The gradient computation is optimized to minimize the memory overhead. Second, we develop a High-Level Synthesis (HLS) based configurable FPGA design that is targeted for edge devices and supports three feature attribution algorithms. Tile based computation is employed to maximally use on-chip resources while adhering to the resource constraints. Representative CNNs are trained on CIFAR-10 dataset and implemented on multiple Xilinx FPGAs using 16-bit fixed-point precision demonstrating flexibility of our library. Finally, through efficient reuse of allocated hardware resources, our design methodology demonstrates a pathway to repurpose inference accelerators to support feature attribution with minimal overhead, thereby enabling real-time XAI on the edge.\",\n \"Title: An Analog Clock-free Compute Fabric base on Continuous-Time Dynamical System for Solving Combinatorial Optimization Problems\\nYear: 2022\\n\\nAbstract: NP-hard combinatorial optimization problems (COPs) are known to be very complex and expensive to solve with traditional computers. COPs can be mapped onto many different kinds of architecture, such as fully digital [1]–[3], event based [4], oscillators [5]–[6], Optical LASER [7], Qbits, or pure analog approach [8]–[9]. We propose a scalable pure analog clock-free continuous-time dynamical system to solve COPs in hardware.\",\n \"Title: Towards CIM-friendly and Energy-Efficient DNN Accelerator via Bit-level Sparsity\\nYear: 2022\\n\\nAbstract: The rising popularity of deep neural network (DNN) algorithms calls for energy-efficient accelerators to enable DNNs run on edge devices. In this paper, we presented BitS-Net, a bit-level sparsity method that quantize the network to desirable numbers with more zeros in their bit representation. We demonstrated that BitS-Net can preserve the accuracy (67.73 %) with accuracy drop ¡1% compared to the original network. Moreover, it achieved up to 5x energy efficiency for ResNet-18 models on the ImageNet dataset compared to the baseline methods.\",\n \"Title: Towards Energy Efficient DNN accelerator via Sparsified Gradual Knowledge Distillation\\nYear: 2022\\n\\nAbstract: Artificial intelligence (AI) is becoming increasingly popular in many applications. However, the computation cost of deep neural network (DNN) , which is a powerful form of AI, calls for efficient DNN compression technique to make energy efficient networks. In this paper, we proposed SKG, a method to jointly sparsify and quantize DNN models to ultra-low bit-precision using Knowledge Distillation and gradual quantization (SKG). We demonstrated that our method can preserve the accuracy more than 20% for uniform quantization with 2 bit-width compared to the baseline methods on ImageNet and ResNet-18. In addition, our method can achieve up to 2.7x lower energy consumption using compute-in-memory (CIM) architecture compared to a traditional 65nm CMOS architecture for both pruned and unpruned network during inference and eventually enabling using DNN models on resource constrained edge devices.\",\n \"Title: Design Space Exploration of Interconnect Materials for Cryogenic Operation: Electrical and Thermal Analyses\\nYear: 2022\\n\\nAbstract: With Copper (Cu) Interconnects causing performance bottleneck at single nanometer nodes due to increase in resistivity size effects viz., grain boundary scattering and surface scattering, there has always been scavenging for alternate interconnect materials. Although the Cu resistivity value decreases at cryogenic temperature, the problems continue to persist. In this work, we study three alternate interconnect materials specifically for 77K High Performance Compute applications. We select the materials based on their resistivity value at 77K for 7nm node computed using Fuchs-Sondheimer-Mayadas-Shatzkes (FS-MS) models. We analyze the delay of the interconnects, understand repeater insertion as a function of wire length, evaluate repeater count and energy at system level and perform IR drop analysis by showing through detailed analytical models that Ru, Rh and Al can provide appreciable improvements over Cu at 77K. The delay of interconnects reduces by 1-3.75% for Ru, 1.5-7.25% for Rh and 4.4-17.8% for Al across the BEOL stack while repeater counts decrease by 10%, 15% and 37% for Ru, Rh and Al respectively at 77K. We investigate thermal and reliability aspects of interconnect design including electromigration, Joule Heating and maximum allowed current densities again proving that Ru (9%), Rh (18%) and Al (63%) outperform Cu at 77K. Finally, we study the effects of various Low-k dielectric materials on the interconnect capacitance and thermal behavior for Cu as well as three alternate materials noting that, even though thermal conductivity of dielectrics decrease at 77K, the Joule Heating will not be as worse as one might expect.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":106,"string":"106"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":53,"string":"53"}}},{"rowIdx":54,"cells":{"question_id":{"kind":"string","value":"Farshad Lahouti"},"question":{"kind":"string","value":"Generate an abstract for the title \"Link-Adaptive and QoS-Provisioning Cooperative ARQ - Applications to Relay-Assisted Land Mobile Satellite Communications.\" using the following items: 1. Cooperative relay network\n2. Cross-layer approach\n3. Adaptive modulation and coding\n4. Truncated cooperative automatic repeat request (C-ARQ)\n5. Data transmission"},"answer":{"kind":"string","value":"In a cooperative relay network, a relay (R) node may facilitate data transmission to the destination (D) node when the latter node cannot correctly decode the source (S) node data. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and the truncated cooperative automatic repeat request (C-ARQ) pr..."},"correct_answer":{"kind":"string","value":"In a cooperative relay network, a relay (R) node may facilitate data transmission to the destination (D) node when the latter node cannot correctly decode the source (S) node data. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and the truncated cooperative automatic repeat request (C-ARQ) pr..."},"documents":{"kind":"list like","value":["Title: Synchrony in Neuronal Communications: An Energy Efficient Scheme.\nYear: 2014\n\nAbstract: We are interested in understanding the neural correlates of attentional processes using first principles. Here we apply a recently developed first principles approach that uses transmitted information in bits per joule to quantify the energy efficiency of information transmission for an inter-spike-interval (ISI) code that can be modulated by means of the synchrony in the presynaptic population. We simulate a single compartment conductance-based model neuron driven by excitatory and inhibitory spikes from a presynaptic population, where the rate and synchrony in the presynaptic excitatory population may vary independently from the average rate. We find that for a fixed input rate, the ISI distribution of the post synaptic neuron depends on the level of synchrony and is well-described by a Gamma distribution for synchrony levels less than 50%. For levels of synchrony between 15% and 50% (restricted for technical reasons), we compute the optimum input distribution that maximizes the mutual information per unit energy. This optimum distribution shows that an increased level of synchrony, as it has been reported experimentally in attention-demanding conditions, reduces the mode of the input distribution and the excitability threshold of post synaptic neuron. This facilitates a more energy efficient neuronal communication.","Title: Spectral Efficiency Optimization for an Interfering Cognitive Radio with Adaptive Modulation and Coding\nYear: 2009\n\nAbstract: In this paper, we consider a primary and a cognitive user transmitting over a\nwireless fading interference channel. The primary user transmits with a\nconstant power and utilizes an adaptive modulation and coding (AMC) scheme\nsatisfying a bit error rate requirement. We propose a link adaptation scheme to\nmaximize the average spectral efficiency of the cognitive radio, while a\nminimum required spectral efficiency for the primary user is provisioned. The\nresulting problem is constrained to also satisfy a bit error rate requirement\nand a power constraint for the cognitive link. The AMC mode selection and power\ncontrol at the cognitive transmitter is optimized based on the modified signal\nto noise plus interference ratio feedback of both links. The problem is then\ncast as a nonlinear discrete optimization problem for which a fast and\nefficient suboptimum solution is presented. We also present a scheme with rate\nadaptive and constant power cognitive radio. An important characteristic of the\nproposed schemes is that no computation or coordination overhead is imposed on\nthe primary radio due to the cognitive radio activity. Numerical results and\ncomparison with the interweave approach to cognitive radio demonstrate the\nefficiency of the proposed solutions.","Title: Network Code Design for Orthogonal Two-hop Network with Broadcasting Relay: A Joint Source Channel Network Coding Approach\nYear: 2012\n\nAbstract: This paper addresses network code design for robust transmission of sources\nover an orthogonal two-hop wireless network with a broadcasting relay. The\nnetwork consists of multiple sources and destinations in which each\ndestination, benefiting the relay signal, intends to decode a subset of the\nsources. Two special instances of this network are orthogonal broadcast relay\nchannel and the orthogonal multiple access relay channel. The focus is on\ncomplexity constrained scenarios, e.g., for wireless sensor networks, where\nchannel coding is practically imperfect. Taking a source-channel and network\ncoding approach, we design the network code (mapping) at the relay such that\nthe average reconstruction distortion at the destinations is minimized. To this\nend, by decomposing the distortion into its components, an efficient design\nalgorithm is proposed. The resulting network code is nonlinear and\nsubstantially outperforms the best performing linear network code. A motivating\nformulation of a family of structured nonlinear network codes is also\npresented. Numerical results and comparison with linear network coding at the\nrelay and the corresponding distortion-power bound demonstrate the\neffectiveness of the proposed schemes and a promising research direction.","Title: RECONSTRUCTION OF MULTI-STAGE VECTOR QUANTIZED SOURCES OVER NOISY CHANNELS- APPLICATIONS TO MELP CODEC\nYear: 2004\n\nAbstract: Design of source decoders that employ the residual redundancy at the source coder output is an interesting research direction in the joint source channelcoding framework. Suchdecodersare ex- pectedto replacethetraditionally heuristicerror concealmentunits that are elements of most multimedia communication systems. In this work, we consider the reconstruction of signals encoded with a Multi-Stage Vector Quantizer andtransmitted over a noisychan- nel. The MSVQ maintains a moderate complexity and, due to its successive refinement feature, is a suitable choice for the design of layered (progressive) source codes. An approximate MMSE source decoder for MSVQ is presented and its application to re- construction of LPC parameters in MELP is analyzed. Numerical results demonstratesthe effectiveness of the proposedschemes.","Title: Link Adaptation with Untrusted Relay Assignment: Design and Performance Analysis\nYear: 2012\n\nAbstract: In this paper, a link adaptation and untrusted relay assignment (LAURA) framework for efficient and reliable wireless cooperative communications with physical layer security is proposed. Using sharp channel codes in different transmission modes, reliability for the destination and security in the presence of untrusted relays (low probability of interception) are provided through rate and power allocation. Within this framework, several schemes are designed for highly spectrally efficient link adaptation and relay selection, which involve different levels of complexity and channel state information requirement. Analytical and simulation performance evaluation of the proposed LAURA schemes are provided, which demonstrates the effectiveness of the presented designs. The results indicate that power adaptation at the source plays a critical role in spectral efficiency performance. Also, it is shown that relay selection based on the signal to noise ratio of the source to relays channels provides an interesting balance of performance and complexity within the proposed LAURA framework.","Title: Lifetime maximized data gathering in wireless sensor networks using limited-order distributed source coding\nYear: 2011\n\nAbstract: This paper addresses the problem of efficient data gathering in wireless sensor networks with a complexity constrained data gathering node. Due to the complexity constraint, the data gathering node employs an asymmetric DSC that (de)compresses the data of a given node exploiting its dependency with a limited number of other nodes. This is characterized in a DSC rate allocation structure that is referred to as limited-order DSC. Within this structure, we investigate the problem of rate allocation for the nodes to maximize the network lifetime. To this end, an algorithm is proposed that is proven optimal with polynomial complexity in terms of number of network nodes. Numerical results demonstrate that the algorithm, even with limited complexity, allows for exploiting most of the achievable compression gain.","Title: Scalar Quantizer Design for Noisy Channel with Decoder Side Information\nYear: 2010\n\nAbstract: A Wyner-Ziv Quantizer design method is introduced when the indices at the output of the encoder are transmitted over a noisy channel. The source encoder is considered as a scalar Lloyd quantizer followed by a binning and an index assignment (BIA) mapping. A modified simulated annealing based algorithm is used for BIA mapping design. A minimax solution for Wyner-Ziv problem under channel mismatch condition is also suggested when the channel is assumed to be binary symmetric channel and no information about the statistic of channel is available except the range of bit error rate. Finally the simulation results are presented which show the effectiveness of the proposed algorithm over other common alternative approaches. These results approve the proposed minimax solution too.","Title: Soft Reconstruction of Speech in the Presence of Noise and Packet Loss\nYear: 2007\n\nAbstract: Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth efficient way to combat the noisy channel degradations. In this paper, we consider soft reconstruction of speech spectrum, in GSM adaptive multirate and IS-641 vocoders, transmitted over a channel disturbed with noise and/or packet loss. Several schemes are presented which exploit different levels of intraframe and interframe residual redundancy for improved source decoding at the receiver. A packetization strategy is proposed which is matched to the presented error concealment units. For decoders that exploit the residual redundancy, extensive complexity has been a serious concern, especially as the quantizer bitrate increases . In this paper, a novel method is presented to construct reduced complexity algorithms. The proposed methodology is based on the classification of the signal domain and efficient approximation of the residual redundancy or the a priori transition probabilities. The presented schemes provide high quality error concealment solutions for code excited linear prediction (CELP) coders","Title: Adaptive Transmission Of Qos-Guaranteed Traffic Over Mimo Wireless Links\nYear: 2008\n\nAbstract: In this paper, we consider the problem of transmission of a bursty data-packet traffic over MIMO space-time diversity fading channels. Aiming at minimizing the packet loss probability due to buffer overflow at the data link layer, we propose a cross-layer analytical framework for transmission policy design which directly satisfies a packet error rate (PER) constraint at the physical layer. Particularly, we present a power and rate adaptation policy for coded M-QAM modulation schemes that are implemented in conjunction with a MIMO diversity system. To enable the transmission policy design, we use a statistical model to characterize the buffer overflow derived from a large deviations result. Numerical results demonstrate that the proposed adaptation policy significantly improves the packet-loss performance for bursty data traffic over MIMO fading channels, when compared to others adaptive solutions.","Title: Performance Analysis of Hybrid CDMA Systems\nYear: 2009\n\nAbstract: In this paper, a hybrid wireless CDMA network composed of ad hoc relays overlaid on a conventional CDMA cellular network is considered. In this setting, effective relaying helps reduce the level of interference at the base stations. The goal of this paper is to investigate the performance improvement in hybrid networks as quantified by the reduction in the probability of outage over the base stations due to interference. A new approximation method to analyze this probability and the average number of active users is introduced. Numerical results and simulations verify the extensive gain obtained by employing ad hoc relaying over the conventional CDMA networks. Moreover, results illustrate the excellent accuracy of the presented analytic approach.","Title: Cross-Layer Link Adaptation Design for Relay Channels with Cooperative ARQ Protocol\nYear: 2008\n\nAbstract: The cooperative automatic repeat request (C-ARQ) is a link layer relaying protocol which exploits the spatial diversity and allows the relay node to retransmit the source data packet to the destination, when the latter is unable to decode the source data correctly. This paper presents a cross-layer link adaptation design for C-ARQ based relay channels in which both source and relay nodes employ adaptive modulation coding and power adaptation at the physical layer. For this scenario, we first derive closed-form expressions for the system spectral efficiency and average power consumption. We then present a low complexity iterative algorithm to find the optimized adaptation solution by maximizing the spectral efficiency subject to a packet loss rate (PLR) and an average power consumption constraint. The results indicate that the proposed adaptation scheme enhances the spectral efficiency noticeably when compared to other adaptive schemes, while guaranteeing the required PLR performance.","Title: Cross-Layer Dynamic Route Selection In Wireless Multiuser Two-Hop Networks\nYear: 2011\n\nAbstract: In mobile Ad-hoc networks forwarding data through intermediate relays extends the coverage area and enhances the network throughput. Dynamic assignment of routes for data transmission from sources to destinations that is optimized based on channel conditions in a cross-layer manner could provide improved performance. We consider a general multiuser two-hop transmission, where each flow is subject to a constraint on the end-to-end buffering delay and its associated packet loss rate as a quality of service requirement. The objective is to maximize the weighted sum-rate between source destination pairs, while the QoS requirement is satisfied. We introduce two new cross-layer dynamic route selection schemes in this setting that are designed involving physical, MAC, and network layers. In cross-layer opportunistic dynamic route selection, the routes are assigned dynamically based on the instantaneous state of fading channels. In time division cross-layer dynamic route selection, the route for data transmission is scheduled based on the average quality of links. Simulation results show that our proposed cross-layer dynamic route selection schemes provide superior performance in comparison to prior art.","Title: Online Multicasting Using Network Coding In Energy Constrained Wireless Ad Hoc Networks\nYear: 2008\n\nAbstract: We consider the optimized joint design of the physical, medium access control, and network layers to maximize the lifetime of energy constrained wireless ad hoc networks for online multicast applications. We consider two types of lifetime definitions, first node failure and multicast functionality. For each definition, we investigate two energy efficient approaches of minimum total energy and min-max per node energy usage to maximize network lifetime. Using network coding at the network layer, the problem of computing multipath flow for both schemes is formulated as a linear optimization problem. Simulation results are provided assessing the effectiveness of the algorithms.","Title: Effective capacity optimization for multiuser diversity systems with adaptive transmission.\nYear: 2012\n\nAbstract: The effective capacity (EC) for a wireless system expresses the maximum arrival source rate that the system can reliably transmit over the wireless channel while fulfilling a probabilistic delay constraint. This paper presents an EC optimization for a multiuser diversity system exploiting proportional opportunistic scheduling at the medium access control layer in conjunction with adaptive modulation and coding (AMC) at the physical layer. We consider the downlink of a time-slotted multiuser system with two different types of channel state information (CSI) at the transmitter, that is, (i) full CSI, whereby each user feeds back its normalized signal-to-noise ratio to the transmitter and (ii) quantized CSI, where each user feeds back the AMC mode for transmission. For each case, we first derive the EC function of the queue service process for the individual users at the medium access control layer. We then design the AMC scheme with power control aiming at maximizing the said function subject to a target packet-error rate constraint. Both independent and identically distributed and time-correlated fading channels are considered. The results illustrate the superior performance of the proposed schemes, when compared with the previous systems such as opportunistic scheduling with single-rate transmission and round-robin scheduling with AMC. Copyright (c) 2012 John Wiley & Sons, Ltd.","Title: Joint Adaptive Modulation Coding and Cooperative ARQ over Relay Channels-Applications to Land Mobile Satellite Communications\nYear: 2008\n\nAbstract: Summary In a cooperative relay network, a relay node (R) facilitates data transmission to the destination node (D), when the latter is unable to decode the source node (S) data correctly. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive a closed form expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme. Aiming at maximizing this performance measure, we then optimize two AMC schemes for S-D and R-D links, which directly satisfy a prescribed packet loss rate constraint. As an interesting application, we also consider the problem of joint link adaptation and blockage mitigation in land mobile satellite communications (LMSC). We also present a new relay-assisted transmission protocol for LMSC, which delivers the source data to the destination via the relaying link, when the S-D channel is in outage. Numerical results indicate that the proposed schemes noticeably enhances the spectral efficiency compared to a system, which uses a conventional ARQ-AMC scheme at the S-D link, or a system which employs an optimized fixed rate cooperative-ARQ protocol.","Title: Channel Feedback Quantization for High Data Rate MIMO Systems\nYear: 2006\n\nAbstract: In this work, we study a multiple-input multiple-output (MIMO) wireless system where the channel state information is partially available at the transmitter through a feedback link. Based on singular value decomposition, the MIMO channel is split into independent sub-channels. Effective feedback of the required spatial channel information entails efficient quantization/encoding of a unitary matrix. We propose two schemes for quantizing unitary matrices via Givens rotations and examine the performance for a scenario where the rates allocated to the sub-channels are selected according to their corresponding gains. Numerical results show that the proposed schemes offer a significant performance improvement as compared to that of MIMO systems without feedback, with a negligible increase in the complexity","Title: Modeling and Analysis of Abnormality Detection in Biomolecular Nano-Networks\nYear: 2012\n\nAbstract: A scheme for detection of abnormality in molecular nano-networks is proposed. This is motivated by the fact that early diagnosis, classification and detection of diseases such as cancer play a crucial role in their successful treatment. The proposed nano-abnormality detection scheme (NADS) comprises of a two-tier network of sensor nano-machines (SNMs) in the first tier and a data gathering node (DGN) at the sink. The SNMs detect the presence of competitor cells as abnormality that is captured by variations in parameters of a nano-communications channel. In the second step, the SNMs transmit micro-scale messages over a noisy micro communications channel (MCC) to the DGN, where a decision is made upon fusing the received signals. The detection performance of each SNM is analyzed by setting up a Neyman-Pearson test. Next, taking into account the effect of the MCC, the overall performance of the proposed NADS is quantified in terms of probabilities of misdetection and false alarm. A design problem is formulated, when the optimized concentration of SNMs in a sample is obtained for a high probability of detection and a limited probability of false alarm.","Title: Channel Sharing in Hybrid Sectorized Cellular Networks with Coverage-Limited Relays\nYear: 2009\n\nAbstract: Ad hoc relaying schemes are introduced as an effective mechanism for load balancing in wireless cellular systems. The relays facilitate channel sharing between the adjacent sectors of the neighboring cells, for the calls that are originated within their coverage area. In this paper, two configurations for relay deployment in sectorized cellular systems are presented. In each case, the probability of blocking in presence of limited-coverage relays and constrained channel sharing is derived. Numerical results verify that the proposed hybrid schemes achieve significantly better grade of service compared to conventional cellular networks.","Title: Multiple Descriptions With Symbol Based Turbo Codes Over Noisy Channels With Packet Loss: Design and Performance Analysis\nYear: 2008\n\nAbstract: Channel optimized multiple description (MD) vector quantization with symbol-based turbo codes are proposed, where the decoder exploits both nonuniformity of descriptions and their dependencies. The joint source channel coding strategy is devised by setting an entropy constraint for quantizer design, which together with the MD index assignment (IA), control the level of redundancy at the MD source ...","Title: Discrete Rate Interfering Cognitive Link Adaptation Design with Primary Link Spectral Efficiency Provisioning.\nYear: 2011\n\nAbstract: We consider a primary and a cognitive user transmitting over a wireless fading interference channel. A discrete rate link adaptation scheme is proposed to maximize the average spectral efficiency of the cognitive radio, while a minimum average spectral efficiency for the primary user is provisioned. The discrete rate scheme for interfering transmission is devised based on two sets of modulation an...","Title: Joint adaptive modulation-coding and cooperative ARQ for wireless relay networks\nYear: 2008\n\nAbstract: This paper presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive an exact closed form expression for the spectral efficiency of the proposed joint AMC - cooperative ARQ scheme. Aiming at maximizing this system performance measure, we then optimize an AMC scheme which directly satisfies a prescribed packet loss rate constraint at the data-link layer. The results indicate that utilizing cooperative ARQ as a retransmission strategy, noticeably enhances the spectral efficiency compared with the system that employs AMC alone at the physical layer. Moreover, the proposed adaptive rate cooperative ARQ scheme outperforms the fixed rate counterpart when the transmission modes at the source and relay are chosen based on the channel statistics. This in turn quantifies the possible gain achieved by joint design of AMC and ARQ in wireless relay networks.","Title: Delay Performance Optimization for Multiuser Diversity Systems with Bursty-Traffic and Heterogeneous Wireless Links\nYear: 2009\n\nAbstract: This paper presents a cross-layer approach for optimizing the delay performance of a multiuser diversity system with heterogeneous block-fading channels and a delay-sensitive bursty-traffic. We consider the downlink of a time-slotted multiuser system employing opportunistic scheduling with fair performance at the medium access (MAC) layer and adaptive modulation and coding (AMC) with power control at the physical layer. Assuming individual user buffers which temporarily store the arrival traffic of users at the MAC layer, we first present a large deviations based statistical model to evaluate the delay-bound violation of packets in the user buffers. Aiming at minimizing the delay probability of the individual users, we then optimize the AMC and power control module subject to a target packet-error rate constraint. In the case of a quantized feedback channel, we also present a constant-power AMC based opportunistic scheduling scheme. Numerical and simulation results are provided to evaluate the delay performance of the proposed adaptation schemes in a multiuser setup.","Title: Spectral Efficiency Optimized Adaptive Transmission for Cognitive Radios in an Interference Channel\nYear: 2009\n\nAbstract: In this paper, we consider a primary and a cognitive user transmitting over a\nwireless fading interference channel. The primary user transmits with a\nconstant power and utilizes an adaptive modulation and coding (AMC) scheme\nsatisfying a bit error rate requirement. We propose a link adaptation scheme to\nmaximize the average spectral efficiency of the cognitive radio, while a\nminimum required spectral efficiency for the primary user is provisioned. The\nresulting problem is constrained to also satisfy a bit error rate requirement\nand a power constraint for the cognitive link. The AMC mode selection and power\ncontrol at the cognitive transmitter is optimized based on the scaled signal to\nnoise plus interference ratio feedback of both links. The problem is then cast\nas a nonlinear discrete optimization problem for which a fast and efficient\nsuboptimum solution is presented. We also present a scheme with rate adaption\nand a constant power. An important characteristic of the proposed schemes is\nthat no negotiation between the users is required. Comparisons with underlay\nand interweave approaches to cognitive radio with adaptive transmission\ndemonstrate the efficiency of the proposed solutions.","Title: Block Network Error Control Codes and Syndrome-based Complete Maximum Likelihood Decoding\nYear: 2008\n\nAbstract: In this paper, network error control coding is studied for robust and efficient multicast in a directed acyclic network with imperfect links. The block network error control coding framework, BNEC, is presented and the capability of the scheme to correct a mixture of symbol errors and packet erasures and to detect symbol errors is studied. The idea of syndrome-based decoding and error detection is introduced for BNEC, which removes the effect of input data and hence decreases the complexity. Next, an efficient three- stage syndrome-based BNEC decoding scheme for network error correction is proposed, in which prior to finding the error values, the position of the edge errors are identified based on the error spaces at the receivers. In addition to bounded-distance decoding schemes for error correction up to the refined Singleton bound, a complete decoding scheme for BNEC is also introduced. Specifically, it is shown that using the proposed syndrome-based complete decoding, a network error correcting code with redundancy order δt for receiver t, can correct δt-1 random additive errors with a probability sufficiently close to 1, if the field size is sufficiently large. Also, a complete maximum likelihood decoding scheme for BNEC is proposed. As the probability of error in different network edges is not equal in general, and given the equivalency of certain edge errors within the network at a particular receiver, the number of edge errors, assessed in the refined Singleton bound, is not a sufficient statistic for ML decoding.","Title: Robust Transmission of Multistage Vector Quantized Sources Over Noisy Communication Channels—Applications to MELP Speech Codec\nYear: 2006\n\nAbstract: Joint source-channel coding is an effective approach for the design of bandwidth efficient and error resilient communication systems with manageable complexity. An interesting research direction within this framework is the design of source decoders that exploit the residual redundancy for effective signal reconstruction at the receiver. Such source decoders are expected to replace the traditional...","Title: Performance analysis of ad-hoc routing in heterogeneous clustered multi-hop wireless networks.\nYear: 2015\n\nAbstract: This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, hop-by-hop routing is known as an efficient decentralized routing algorithm which selects the best relay node in each hop using local channel state information. In this article, we combine hop-by-hop routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Numerical results are provided to validate the correctness of the presented analyses.","Title: Performance Analysis of Ad-Hoc Routing in Clustered Multi-hop Wireless Networks.\nYear: 2014\n\nAbstract: This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, ad-hoc routing is known as an efficient decentralized routing algorithm which selects the best relay node on a hop-by-hop basis using local channel state information. In this article, we combine ad-hoc routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Simulation results are provided to validate the correctness of the presented analyses.","Title: Design of LDPC Codes Robust to Noisy Message-Passing Decoding.\nYear: 2015\n\nAbstract: We address noisy message-passing decoding of lowdensity parity-check (LDPC) codes over additive white Gaussian noise channels. Message-passing decoders in which certain processing units iteratively exchange messages are common for decoding LDPC codes. The exchanged messages are in general subject to internal noise in hardware implementation of these decoders. We model the internal decoder noise as additive white Gaussian noise (AWGN) degrading exchanged messages. Using Gaussian approximation of the exchanged messages, we perform a two-dimensional density evolution analysis for the noisy LDPC decoder. This makes it possible to track both the mean, and the variance of the exchanged message densities, and hence, to quantify the threshold of the LDPC code in the presence of internal decoder noise. The numerical and simulation results are presented that quantify the performance loss due to the internal decoder noise. To partially compensate this performance loss, we propose a simple method, based on EXIT chart analysis, to design robust irregular LDPC codes. The simulation results indicate that the designed codes can indeed compensate part of the performance loss due to the internal decoder noise.","Title: On Capacity and Capacity per Unit Cost of Gaussian Multiple Access Channel with Peak Power Constraints.\nYear: 2014\n\nAbstract: This paper investigates the capacity and capacity per unit cost of Gaussian multiple access-channel (GMAC) with peak power constraints. We first devise an approach based on Blahut-Arimoto Algorithm to numerically optimize the sum rate and quantify the corresponding input distributions. The results reveal that in the case with identical peak power constraints, the user with higher SNR is to have a symmetric antipodal input distribution for all values of noise variance. Next, we analytically derive and characterize an achievable rate region for the capacity in cases with small peak power constraints, which coincides with the capacity in a certain scenario. The capacity per unit cost is of interest in low power regimes and is a target performance measure in energy efficient communications. In this work, we derive the capacity per unit cost of additive white Gaussian channel and GMAC with peak power constraints. The results in case of GMAC demonstrate that the capacity per unit cost is obtained using antipodal signaling for both users and is independent of users rate ratio. We characterize the optimized transmission strategies obtained for capacity and capacity per unit cost with peak-power constraint in detail and specifically in contrast to the settings with average-power constraints.","Title: Distributed Cross-layer Dynamic Route Selection in Wireless Multiuser Multihop Networks.\nYear: 2014\n\nAbstract: In wireless ad-hoc networks, forwarding data through intermediate relays extends the coverage area and enhances the network throughput. We consider a general wireless multiuser multihop transmission, where each data flow is subject to a constraint on the end-to-end buffering delay and the associated packet drop rate as a quality of service (QoS) requirement. The objective is to maximize the weighted sum-rate between source destination pairs, while the corresponding QoS requirements are satisfied. We introduce two new distributed cross-layer dynamic route selection schemes in this setting that are designed involving physical, MAC, and network layers. In the proposed opportunistic cross-layer dynamic route selection scheme, routes are assigned dynamically based on the state of network nodes' buffers and the instantaneous state of fading channels. In the same setting, the proposed time division cross layer dynamic route selection scheme utilizes the average quality of channels instead for more efficient implementation. Detailed results and comparisons are provided, which demonstrate the superior performance of the proposed cross-layer dynamic route selection schemes.","Title: A key pre-distribution scheme based on multiple block codes for wireless sensor networks\nYear: 2014\n\nAbstract: A key pre-distribution scheme (KPS) based on multiple codewords of block codes is presented for wireless sensor networks. The connectivity and security of the proposed KPS, quantified in terms of probabilities of sharing common keys for communications of pairs of nodes and their resilience against colluding nodes, are analytically assessed. The analysis is applicable to both linear and nonlinear codes and is simplified in the case of maximum distance separable codes. It is shown that the multiplicity of codes significantly enhances the security and connectivity of KPS at the cost of a modest increase of the nodes storage. Numerical and simulation results are provided, which sheds light on the effect of system parameters of the proposed KPS on its complexity and performance. Specifically, it is shown that the probability of resilience of secure pairs against collusion of other nodes only reduces slowly as the number of colluding nodes increase.","Title: A matrix completion approach to linear index coding problem\nYear: 2014\n\nAbstract: In this paper, a general algorithm is proposed for rate analysis and code design of linear index coding problems. Specifically a solution for minimum rank matrix completion problem over finite fields representing the linear index coding problem is devised in order to find the optimum transmission rate given vector length and size of the field. The new approach can be applied to both scalar and vector linear index coding.","Title: Multi-level Distributed Arithmetic Coding with Nested Lattice Quantization\nYear: 2014\n\nAbstract: In this paper, a scheme based on 1-D nested lattice quantization followed by multi-level distributed arithmetic coding (MLDAC) as the Slepian-Wolf (SW) code is proposed for the lossy source coding of continuous sources. This system can be employed in distributed video and image coding applications. The output of the quantizer is first converted to binary, and then the SW coding is applied on each bit plane. An efficient algorithm for joint decoding of bit planes at the decoder is proposed, which exploits the dependency of the bit planes with each other and the side-information available at the decoder. Also, a methodology for rate allocation among the bit planes is presented. The quantization parameters are designed to improve the end-to-end system performance based on its overall rate-distortion function taking into account both the distortions due to quantization and imperfect practical Slepian-Wolf coding. The simulation results demonstrate the effectiveness of the proposed MLDAC with the lattice quantization.","Title: Quantization of LSF parameters using a trellis modeling\nYear: 2003\n\nAbstract: An efficient block-based trellis quantization (BTQ) scheme is proposed for the quantization of the line spectral frequencies (LSF) in speech coding applications. The scheme is based on the modeling of the LSF intraframe dependencies with a trellis structure. The ordering property and the fact that LSF parameters are bounded within a range is explicitly incorporated in the trellis model. BTQ search and design algorithms are discussed and an efficient algorithm for the index generation (finding the index of a path in the trellis) is presented. Also the sequential vector decorrelation technique is presented to effectively exploit the intraframe correlation of LSF parameters within the trellis. Based on the proposed block-based trellis quantizer, two intraframe schemes and one interframe scheme are proposed. Comparisons to the split-VQ, the trellis coded quantization of LSF parameters, and the multi-stage VQ, as well as the interframe scheme used in IS-641 EFRC and the GSM AMR codec are provided. These results demonstrate that the proposed BTQ schemes outperform the above systems.","Title: Reconstruction of predictively encoded signals over noisy channels using a sequence MMSE decoder\nYear: 2004\n\nAbstract: Abstract Inthis work, we considertheproblem ofdecoding apredictively encodedsignal over anoisy channel whenthereisaresidualredundancy(capturedbya ∞-orderMarkovmodel)inthesequenceoftransmitted data. Ourobjectiveistominimizethemeansquarederrorinthereconstructionoftheoriginalsignal(input to the predictive source coder). The problem is formulated and solved through Minimum Mean Squared Error(MMSE)decodingofasequenceofsamplesoveramemorylessnoisychannel. Therelatedprevious works include several MAP and MMSE-based decoders. The MAP-based approaches are suboptimal when the performance criterion is the mean squared error. On the other hand, the previously known MMSE-basedapproachesaresuboptimalsincetheyaredesignedtoe‐cientlyreconstructthedatasamples received (the prediction residues) rather than the original signal. The proposed scheme,is setup by modeling the source coder produced symbols and their redundancy with a trellis structure. Methods are presented to optimize the solutions in terms of complexity. Numerical results and comparisons are provided which demonstrate the efiectiveness of the proposed techniques. Keywords Jointsourcechannelcoding residualredundancies sourcedecoding MMSEestimation MAPdetec-","Title: Queuing with Adaptive Modulation over MIMO Wireless Links for Deadline Constrained Traffic: Cross-Layer Analysis and Design\nYear: 2007\n\nAbstract: Abstract-In this paper, we consider a deadline constrained traffic and ,analyze the joint effects of packet ,queuing and adaptive modulation (AM) for packet transmission in MIMO systems. We present a general analytical procedure, and derive the achievable delay-bound violation probability, the packet loss rate, and the average throughput of AM in MIMO wireless links employing orthogonal space time block coding (STBC) over Nakagami fading channels. In the proposed analytical procedure, weuse,statistical delay-bound for deadline constrained traffic based,on the ,effective bandwidth ,theory. Based on our performance analysis, we propose a cross-layer design, which selects the optimal target packet error rate of AM at the physical layer, to minimize the packet loss rate and maximize the average throughput, when combined with packet queuing at the data link layer. Numerical ,results demonstrate ,that ,the ,system performance depends on various parameters, and show the performance,gain due to cross-layer design. We also ,discuss briefly possible applications of our proposed modeling to quality of service guarantee in multiuser scenarios.","Title: A Decentralized Approach to Network Coding Based on Learning\nYear: 2007\n\nAbstract: In this paper, we introduce a new efficient method based on reinforcement learning to construct linear network codes, referred to as the Reinforcement Learning Network Code (RLNC) design. We will make use of the market theory concepts in the learning section of the algorithm. The learning approach results in a smart random search and we demonstrate that the proposed algorithm is decentralized, and polynomial time complex. The RLNC algorithm constructs network codes faster than the random method of (4) with the same complexity order, especially in large networks with small field sizes. It is also shown that the algorithm can re-construct the network code in the presence of link failures with a small complexity and without previously being aware of error patterns even in very large networks. Further extension to achieve the objective of decreasing the number of encoding nodes in a network is discussed.","Title: Robust Network Coding in the Presence of Link Failure Using a Multicast Rate-Diversity Trade off\nYear: 2007\n\nAbstract: We introduce a centralized joint network- channel coding scheme for maximized throughput and increased robustness against link failure in a communication network. We introduce RNC1(h,k) to multicast k independent data in a directed and acyclic network with capacity h, h k ≤ . The redundancy through path diversity increases the resistance of the network against link failure. An improved version of RNC1, RNC2(h,k), is introduced to guarantee the rate k for h-k flow failures. The proposed schemes exploit the network structure for code design, which results in a manageable design complexity.","Title: Optimizing Delay Performance over MIMO Fading Channels with Adaptive Transmission\nYear: 2008\n\nAbstract: In this paper, we consider the problem of transmitting a delay-sensitive and bursty traffic over a time- varying MIMO Nakagami-ra fading channel, and optimize the delay performance of packet queuing at the data link layer. We use a statistical model to characterize the packet delay derived from a known large deviations result, and allows for analytical insights into transmission policy design. We derive power and rate adaptation policies for coded M-QAM modulation schemes that are implemented in conjunction with a MIMO diversity system; such that the packet delay probability is minimized subject to a prescribed channel packet error rate constraint. This is also equivalent to minimizing the system packet loss rate. The proposed adaptation policies depend not only on channel conditions but also on the quality of service performance at the data link layer. Numerical results show that the proposed cross- layer adaptation policies significantly improve the delay performance for delay-sensitive bursty traffic over MIMO fading channels, when compared to others adaptive solutions.","Title: Adaptive transmission policy design for delay-sensitive and bursty packet traffic over wireless fading channels\nYear: 2009\n\nAbstract: In this paper, we consider the problem of transmission of a delay-sensitive and bursty traffic source over a time-varying Nakagami-m fading channel in a cross-layer optimization framework. Aiming at minimizing the packet delay due to queuing at the data link layer, we present power and rate adaptation policies for coded M-QAM modulation schemes, which guarantee a prescribed channel packet error rate constraint. This is also equivalent to minimizing the system packet loss rate. The proposed adaptation policies are derived both for block and correlated channel fading scenarios. To enable the transmission policy design, we use a statistical model to characterize the packet delay derived from a known result of large deviations theory. Considering the error resolution capability of the automatic repeat request protocol, we then provide the appropriate analytical tools to incorporate the effect of packet retransmission in the proposed optimization framework for transmission policy design. The results show that the proposed adaptation policies compared to others adaptive solutions, significantly improve the delay and throughput performance for delay-sensitive bursty traffic over time-varying fading channels.","Title: A flexible rate slepian-wolf code construction\nYear: 2009\n\nAbstract: A flexible rate Slepian-Wolf (SW) code is constructed, which is vital for wireless sensor network applications. The proposed solution is based on an efficient and practical algorithm to compute the syndrome of the rate-compatible convolutional codes (RCPC). Using this algorithm, there is no need to compute the syndrome of punctured version of the mother code for each puncturing matrix, which is complex. Instead, the syndrome of the punctured code is the punctured version of the syndrome of the mother code using the same pattern of puncturing. The algorithm is general for all convolutional codes in Zq. The strategy is also generalized for parallel and serial concatenated convolutional codes. For the cases, where the dependencies among sources are modeled as a virtual discrete channel, a simplified decoding scheme is suggested. This method is generalized to achieve all points on the SW boundary using a simple code design technique. Simulation results demonstrate the performance and effectiveness of the proposed methods.","Title: Link adaptation for physical layer security over wireless fading channels\nYear: 2012\n\nAbstract: A secure link adaptation framework is proposed, which exploits the inherent fluctuations of wireless fading channels for high-performance communications and physical layer security in the presence of an eavesdropper. The authors use very sharp channel codes intended for reliability and demonstrate that they also provide security, when successfully incorporated in the link adaptation design framework and the security constraint is not very stringent. Two scenarios are considered in which the transmitter has access to the eavesdropper channel state information either instantaneously or statistically. The proposed secure link adaptation framework is formulated to maximise the spectral efficiency of the communication, whereas both reliability and security constraints are provisioned. Different designs are considered when the security constraint is quantified by instantaneous bit error rate (BER), average BER or leakage probability. For the problem with instantaneous BER constraint, an efficient analytical solution and a numerical solution are presented. A closed-form analytical solution is also provided for secure link adaptation with average BER constraint, whereas the problem with the leakage constraint is tackled numerically. Extensive results and detailed analysis are provided to draw insights on the effects of different design parameters on the performance.","Title: Multi-Mode Nested Quantization in Presence of Uncertain Side Information and Feedback\nYear: 2013\n\nAbstract: In this paper, the problem of uniform quantization for the Wyner-Ziv (WZ) problem in presence of uncertain side information at the encoder is addressed. The uncertain side information problem arises in data compression with side information (SI) when the joint probability distribution of source and SI is not (fully) known at the encoder. The uncertainty is due to the time varying nature of the dependency of source and SI in settings such as wireless sensor networks and distributed video coding. In this paper, a solution is proposed which consists of a multi-mode WZ encoder in conjunction with a carefully designed feedback scheme from the decoder. Each encoder mode is associated with a uniform nested quantizer. In this framework, the quantization parameters, the feedback scheme, and the source coding rate are jointly optimized to minimize the average rate or distortion. Two distinct schemes with adaptive or fixed transmission rate are proposed. Simulation results are provided which demonstrate the effectiveness of the presented solutions and assess the effect of different design parameters including the number of modes (feedback rate) on the performance.","Title: Delay-Limited Source and Channel Coding of Quasi-Stationary Sources over Block Fading Channels: Design and Scaling Laws\nYear: 2012\n\nAbstract: In this paper, delay-limited transmission of quasi-stationary sources over block fading channels is considered. Considering distortion outage probability as the performance measure, two source and channel coding schemes with power adaptive transmission are presented. The first one is optimized for fixed rate transmission, and hence enjoys simplicity of implementation. The second one is a high performance scheme, which also benefits from optimized rate adaptation with respect to source and channel states. In high SNR regime, the performance scaling laws in terms of outage distortion exponent and asymptotic outage distortion gain are derived, where two schemes with fixed transmission power and adaptive or optimized fixed rates are considered as benchmarks for comparisons. Various analytical and numerical results are provided which demonstrate a superior performance for source and channel optimized rate and power adaptive scheme. It is also observed that from a distortion outage perspective, the fixed rate adaptive power scheme substantially outperforms an adaptive rate fixed power scheme for delay-limited transmission of quasi-stationary sources over wireless block fading channels. The effect of the characteristics of the quasi-stationary source on performance, and the implication of the results for transmission of stationary sources are also investigated.","Title: A Type II Hybrid ARQ Protocol with Adaptive Modulation and Coding for Time-Correlated Fading Channels: Analysis and Design\nYear: 2010\n\nAbstract: This paper presents performance analysis and cross-layer design approaches for hybrid ARQ (HARQ) protocol in wireless networks which employ adaptive modulation and coding (AMC) at the physical layer and are subject to time-correlated fading channels. Utilizing a Markov channel model which accounts for the temporal correlation in successive parity transmissions by the adaptive rate HARQ protocol, we derive the system throughput and the packet loss probability based on a rate compatible punctured convolutional (RCPC) code family. As an application, we then present a cross-layer AMC design which takes into account the performance gain of the HARQ protocol at the link layer. The results illustrate that including AMC in the HARQ protocol leads to a substantial throughput gain, but the channel correlation strongly diminishes the performance of the HARQ protocol in terms of throughput and packet loss rate.","Title: Information Rates of ASK-Based Molecular Communication in Fluid Media.\nYear: 2015\n\nAbstract: This paper studies the capacity of molecular communications in fluid media, where the information is encoded in the number of transmitted molecules in a time-slot (amplitude shift keying). The propagation of molecules is governed by random Brownian motion and the communication is in general subject to intersymbol interference (ISI). We first consider the case where ISI is negligible and analyze th...","Title: Bounds on the Capacity of ASK Molecular Communication Channels with ISI\nYear: 2015\n\nAbstract: There are now several works on the use of the additive inverse Gaussian noise (AIGN) model for the random transit time in molecular communication (MC) channels. The randomness invariably causes inter- symbol interference (ISI) in MC, an issue largely ignored or simplified. In this paper we derive an upper bound and two lower bounds for MC based on amplitude shift keying (ASK) in presence of ISI. The Blahut-Arimoto algorithm (BAA) is modified to find the input distribution of transmitted symbols to maximize the lower bounds. Our results show that over wide parameter values the bound are close.","Title: Constellation Shaping and LDPC Coding in a Bidirectional Full Duplex Communication.\nYear: 2015\n\nAbstract: We investigate the ability of the physical layer approaches of constellation shaping and forward error correction to enhance the performance of full duplex (FD) wireless radio systems. We use low density parity check and optimized shaping codes to transmit non-equiprobable constellation points from an amplitude phase shift keying modulation with imperfect power amplifier and in the presence of FD residual self interference. A simple approach to the design of optimized shaping codes for a given signal to noise ratio and residual self interference power is presented. Simulation results show that a FD transceiver with bit interleaved coded modulation, optimized shaping and iterative demodulation and decoding noticeably improves the performance in comparison to the same system without constellation shaping.","Title: Distortion-Power Tradeoffs in Quasi-Stationary Source Transmission Over Delay and Buffer Limited Block Fading Channels.\nYear: 2016\n\nAbstract: This paper investigates distortion-power tradeoffs in transmission of quasi-stationary sources over delay and buffer limited block fading channels by studying encoder and decoder buffering techniques to smooth out the source and channel variations. Four source and channel coding schemes that consider buffer and power constraints are presented to minimize the reconstructed source distortion. The fi...","Title: RCFD: A Novel Channel Access Scheme for Full-Duplex Wireless Networks Based on Contention in Time and Frequency Domains.\nYear: 2018\n\nAbstract: In the last years, the advancements in signal processing and integrated circuits technology allowed several research groups to develop working prototypes of in-band full-duplex wireless systems. The introduction of such a revolutionary concept is promising in terms of increasing network performance, but at the same time poses several new challenges, especially at the MAC layer. Consequently, innov...","Title: Resource Allocation In Ofdma Networks With Half-Duplex And Imperfect Full-Duplex Users\nYear: 2016\n\nAbstract: Recent studies indicate the feasibility of in-band fullduplex (FD) wireless communications, where a wireless radio transmits and receives simultaneously in the same band. Due to its potential to increase the capacity, analyzing the performance of a cellular network that contains full-duplex devices is crucial. In this paper, we consider maximizing the weighted sum-rate of downlink and uplink of a single cell OFDMA network which consists of an imperfect FD base-station (BS) and a mixture of half-duplex and imperfect full-duplex mobile users. To this end, the joint problem of sub-channel assignment and power allocation is investigated and a two-step solution is proposed. A heuristic algorithm to allocate each sub-channel to a pair of downlink and uplink users with polynomial complexity is presented. The power allocation problem is convexified based on the difference of two concave functions approach, for which an iterative solution is obtained. Simulation results demonstrate that when all the users and the BS are perfect FD nodes the network throughput could be doubled, Otherwise, the performance improvement is limited by the inter-node interference and the self-interference. We also investigate the effect of the self-interference cancellation capability and the percentage of FD users on the network performance in both indoor and outdoor scenarios.","Title: RCFD: A Frequency Based Channel Access Scheme for Full Duplex Wireless Networks.\nYear: 2016\n\nAbstract: Recently, several working implementations of in--band full--duplex wireless systems have been presented, where the same node can transmit and receive simultaneously in the same frequency band. The introduction of such a possibility at the physical layer could lead to improved performance but also poses several challenges at the MAC layer. In this paper, an innovative mechanism of channel contention in full--duplex OFDM wireless networks is proposed. This strategy is able to ensure efficient transmission scheduling with the result of avoiding collisions and effectively exploiting full--duplex opportunities. As a consequence, considerable performance improvements are observed with respect to standard and state--of--the--art MAC protocols for wireless networks, as highlighted by extensive simulations performed in ad hoc wireless networks with varying number of nodes.","Title: Abnormality Detection in Correlated Gaussian Molecular Nano-Networks: Design and Analysis.\nYear: 2016\n\nAbstract: A nano-abnormality detection scheme (NADS) in molecular nano-networks is studied. This is motivated by the fact that early detection of diseases such as cancer plays a crucial role in their successful treatment. The proposed NADS is in fact a two-tier network of sensor nano-machines (SNMs) in the first tier and a data-gathering node (DGN) at the sink. The SNMs detect the presence of competitor cel...","Title: Statistical Qos Analysis Of Full Duplex And Half Duplex Heterogeneous Cellular Networks\nYear: 2016\n\nAbstract: In this paper, statistical Quality of Service provisioning in next generation heterogeneous mobile cellular networks is investigated. To this aim, any active entity of the cellular network is regarded as a queuing system, whose statistical QoS requirements depend on the specific application. In this context, by quantifying the performance in terms of effective capacity, we introduce a lower bound for the system performance that facilitates an efficient analysis. We exploit this analytical framework to give insights about the possible improvement of the statistical QoS experienced by the users if the current heterogeneous cellular network architecture migrates from a Half Duplex to a Full Duplex mode of operation. Numerical results and analysis are provided, where the network is modeled as a Matern point processes with a hard core distance. The results demonstrate the accuracy and computational efficiency of the proposed scheme, especially in large scale wireless systems.","Title: Analysis of key generation rate from wireless channel in in-band full-duplex communications\nYear: 2016\n\nAbstract: In this paper, the impact of in-band full-duplex (IBFD) wireless communications on secret key generation via physical layer channel state information is investigated. A key generation strategy for IBFD wireless devices to increase the rate of generated secret keys over multipath fading channels is proposed. Conventionally, due to the half-duplex (HD) constraint on wireless transmissions, sensing simultaneous reciprocal channel measurements is not possible, which leads to a degraded key generation rate. However, with the advent of IBFD wireless devices, the legitimate nodes can sense the shared wireless link simultaneously at the possible cost of a self-interference (SI) channel estimation and some residual self-interference (RSI). As we demonstrate, with HD correlated observations the key rate is upper bounded by a constant, while with IBFD the key rate is only limited by the SI cancellation performance and is in general greater than that of its HD counterpart. Our analysis shows that with reasonable levels of SI cancellation, in the high SNR regime the key rate of IBFD is much higher, while in low SNRs, the HD system performs better. Finally, the key rate loss due to the overhead imposed by the SI channel estimation phase is discussed.","Title: Automatic fault detection and diagnosis in cellular networks using operations support systems data.\nYear: 2016\n\nAbstract: Self-Healing is one of the key important functionalities in self-organizing mobile communication networks. Despite its importance, self-healing has yet to receive a deserving research attention in the literature. This paper considers important quality indicators in a live mobile communications network and presents an automatic unified detection and diagnosis framework to identify root causes of faults occurred in the network. The proposed solution relies on unsupervised clustering of both traffic and signaling (continuous) key performance indicators for diagnosis. Hence, it is immune to the human error in the modeling phase. It also allows to effectively encapsulate experts knowledge as they relate clusters to root causes in the design phase. Detailed analysis of fault detection, the clustering schemes and the diagnosis are provided using operations support systems data of a real cellular network.","Title: Analysis of Statistical QoS in Half Duplex and Full Duplex Dense Heterogeneous Cellular Networks.\nYear: 2017\n\nAbstract: Statistical QoS provisioning as an important performance metric in analyzing next generation mobile cellular network, aka 5G, is investigated. In this context, by quantifying the performance in terms of the effective capacity, we introduce a lower bound for the system performance that facilitates an efficient analysis. Based on the proposed lower bound, which is mainly built on a per resource block analysis, we build a basic mathematical framework to analyze effective capacity in an ultra dense heterogeneous cellular network. We use our proposed scalable approach to give insights about the possible enhancements of the statistical QoS experienced by the end users if heterogeneous cellular networks migrate from a conventional half duplex to an imperfect full duplex mode of operation. Numerical results and analysis are provided, where the network is modeled as a Matern point process. The results demonstrate the accuracy and computational efficiency of the proposed scheme, especially in large scale wireless systems. Moreover, the minimum level of self interference cancellation for the full duplex system to start outperforming its half duplex counterpart is investigated.","Title: Resource Allocation in Heterogenous Full-duplex OFDMA Networks: Design and Analysis.\nYear: 2018\n\nAbstract: Recent studies indicate the feasibility of full-duplex (FD) bidirectional wireless communications. Due to its potential to increase the capacity, analyzing the performance of a cellular network that contains full-duplex devices is crucial. In this paper, we consider maximizing the weighted sum-rate of downlink and uplink of an FD heterogeneous OFDMA network where each cell consists of an imperfect FD base-station (BS) and a mixture of half-duplex and imperfect full-duplex mobile users. To this end, first, the joint problem of sub-channel assignment and power allocation for a single cell network is investigated. Then, the proposed algorithms are extended for solving the optimization problem for an FD heterogeneous network in which intra-cell and inter-cell interferences are taken into account. Simulation results demonstrate that in a single cell network, when all the users and the BSs are perfect FD nodes, the network throughput could be doubled. Otherwise, the performance improvement is limited by the inter-cell interference, inter-node interference, and self-interference. We also investigate the effect of the percentage of FD users on the network performance in both indoor and outdoor scenarios, and analyze the effect of the self-interference cancellation capability of the FD nodes on the network performance.","Title: Exact Assessment of the Delay-Rate Tradeoff in Ergodic Interference Alignment.\nYear: 2018\n\nAbstract: In order to increase the network capacity and fulfill the Quality of Service requirements in multi-user wireless networks, interference alignment (IA) has been proposed. Subsequently, ergodic IA was introduced as a promising scheme to achieve a degrees-of-freedom metric equal to (1/2), at the expense of additional delay. In this letter, we study the delay-rate trade-off in ergodic IA and exactly c...","Title: Analysis of distributed ADMM algorithm for consensus optimisation over lossy networks.\nYear: 2018\n\nAbstract: Alternating direction method of multipliers (ADMM) is a popular convex optimisation algorithm, which is implemented in a distributed manner. Applying this algorithm to consensus optimisation problem, where a number of agents cooperatively try to solve an optimisation problem using locally available data, leads to a fully distributed algorithm which relies on local computations and communication be...","Title: Analysis of Distributed ADMM Algorithm for Consensus Optimization in Presence of Node Error.\nYear: 2019\n\nAbstract: Alternating direction method of multipliers (ADMM) is a popular convex optimization algorithm, which can be employed for solving distributed consensus optimization problems. In this setting, agents locally estimate the optimal solution of an optimization problem and exchange messages with their neighbors over a connected network. The distributed algorithms are typically exposed to different types ...","Title: Neuronal Synchronization Can Control the Energy Efficiency of Inter-Spike Interval Coding\nYear: 2018\n\nAbstract: The role of synchronous firing in sensory coding and cognition remains controversial. While studies, focusing on its mechanistic consequences in attentional tasks, suggest that synchronization dynamically boosts sensory processing, others failed to find significant synchronization in such tasks. We attempt to understand both lines of evidence within a coherent theoretical framework. We conceptualize synchronization as an independent control parameter to study how the postsynaptic neuron transmits the average firing activity of a presynaptic population, in the presence of synchronization. We apply the Berger-Levy theory of energy efficient information transmission to interpret simulations of a Hodgkin-Huxley-type postsynaptic neuron model, where we varied independently the firing rate and synchronization level in the presynaptic population. We find that for a fixed presynaptic firing rate the simulated postsynaptic interspike interval distribution depends on the synchronization level and is well-described by a generalized extreme value distribution. For synchronization levels of 15% to 50%, we find that the optimal distribution of presynaptic firing rate, maximizing the mutual information per unit cost, is maximized at ~30% synchronization level. These results suggest that the statistics and energy efficiency of neuronal communication channels, through which the input rate is communicated, can be dynamically adapted by the synchronization level.","Title: How to Query an Oracle? Efficient Strategies to Label Data\nYear: 2022\n\nAbstract: We consider the basic problem of querying an expert oracle for labeling a dataset in machine learning. This is typically an expensive and time consuming process and therefore, we seek ways to do so efficiently. The conventional approach involves comparing each sample with (the representative of) each class to find a match. In a setting with \n<inline-formula><tex-math notation=\"LaTeX\">$N$</tex-math></inline-formula>\n equally likely classes, this involves \n<inline-formula><tex-math notation=\"LaTeX\">$N/2$</tex-math></inline-formula>\n pairwise comparisons (queries per sample) on average. We consider a \n<inline-formula><tex-math notation=\"LaTeX\">$k$</tex-math></inline-formula>\n-ary query scheme with \n<inline-formula><tex-math notation=\"LaTeX\">$k\\geq 2$</tex-math></inline-formula>\n samples in a query that identifies (dis)similar items in the set while effectively exploiting the associated transitive relations. We present a randomized batch algorithm that operates on a round-by-round basis to label the samples and achieves a query rate of \n<inline-formula><tex-math notation=\"LaTeX\">$O(\\frac{N}{k^2})$</tex-math></inline-formula>\n. In addition, we present an adaptive greedy query scheme, which achieves an average rate of \n<inline-formula><tex-math notation=\"LaTeX\">$\\approx 0.2N$</tex-math></inline-formula>\n queries per sample with triplet queries. For the proposed algorithms, we investigate the query rate performance analytically and with simulations. Empirical studies suggest that each triplet query takes an expert at most 50% more time compared with a pairwise query, indicating the effectiveness of the proposed \n<inline-formula><tex-math notation=\"LaTeX\">$k$</tex-math></inline-formula>\n-ary query schemes. We generalize the analyses to nonuniform class distributions when possible."],"string":"[\n \"Title: Synchrony in Neuronal Communications: An Energy Efficient Scheme.\\nYear: 2014\\n\\nAbstract: We are interested in understanding the neural correlates of attentional processes using first principles. Here we apply a recently developed first principles approach that uses transmitted information in bits per joule to quantify the energy efficiency of information transmission for an inter-spike-interval (ISI) code that can be modulated by means of the synchrony in the presynaptic population. We simulate a single compartment conductance-based model neuron driven by excitatory and inhibitory spikes from a presynaptic population, where the rate and synchrony in the presynaptic excitatory population may vary independently from the average rate. We find that for a fixed input rate, the ISI distribution of the post synaptic neuron depends on the level of synchrony and is well-described by a Gamma distribution for synchrony levels less than 50%. For levels of synchrony between 15% and 50% (restricted for technical reasons), we compute the optimum input distribution that maximizes the mutual information per unit energy. This optimum distribution shows that an increased level of synchrony, as it has been reported experimentally in attention-demanding conditions, reduces the mode of the input distribution and the excitability threshold of post synaptic neuron. This facilitates a more energy efficient neuronal communication.\",\n \"Title: Spectral Efficiency Optimization for an Interfering Cognitive Radio with Adaptive Modulation and Coding\\nYear: 2009\\n\\nAbstract: In this paper, we consider a primary and a cognitive user transmitting over a\\nwireless fading interference channel. The primary user transmits with a\\nconstant power and utilizes an adaptive modulation and coding (AMC) scheme\\nsatisfying a bit error rate requirement. We propose a link adaptation scheme to\\nmaximize the average spectral efficiency of the cognitive radio, while a\\nminimum required spectral efficiency for the primary user is provisioned. The\\nresulting problem is constrained to also satisfy a bit error rate requirement\\nand a power constraint for the cognitive link. The AMC mode selection and power\\ncontrol at the cognitive transmitter is optimized based on the modified signal\\nto noise plus interference ratio feedback of both links. The problem is then\\ncast as a nonlinear discrete optimization problem for which a fast and\\nefficient suboptimum solution is presented. We also present a scheme with rate\\nadaptive and constant power cognitive radio. An important characteristic of the\\nproposed schemes is that no computation or coordination overhead is imposed on\\nthe primary radio due to the cognitive radio activity. Numerical results and\\ncomparison with the interweave approach to cognitive radio demonstrate the\\nefficiency of the proposed solutions.\",\n \"Title: Network Code Design for Orthogonal Two-hop Network with Broadcasting Relay: A Joint Source Channel Network Coding Approach\\nYear: 2012\\n\\nAbstract: This paper addresses network code design for robust transmission of sources\\nover an orthogonal two-hop wireless network with a broadcasting relay. The\\nnetwork consists of multiple sources and destinations in which each\\ndestination, benefiting the relay signal, intends to decode a subset of the\\nsources. Two special instances of this network are orthogonal broadcast relay\\nchannel and the orthogonal multiple access relay channel. The focus is on\\ncomplexity constrained scenarios, e.g., for wireless sensor networks, where\\nchannel coding is practically imperfect. Taking a source-channel and network\\ncoding approach, we design the network code (mapping) at the relay such that\\nthe average reconstruction distortion at the destinations is minimized. To this\\nend, by decomposing the distortion into its components, an efficient design\\nalgorithm is proposed. The resulting network code is nonlinear and\\nsubstantially outperforms the best performing linear network code. A motivating\\nformulation of a family of structured nonlinear network codes is also\\npresented. Numerical results and comparison with linear network coding at the\\nrelay and the corresponding distortion-power bound demonstrate the\\neffectiveness of the proposed schemes and a promising research direction.\",\n \"Title: RECONSTRUCTION OF MULTI-STAGE VECTOR QUANTIZED SOURCES OVER NOISY CHANNELS- APPLICATIONS TO MELP CODEC\\nYear: 2004\\n\\nAbstract: Design of source decoders that employ the residual redundancy at the source coder output is an interesting research direction in the joint source channelcoding framework. Suchdecodersare ex- pectedto replacethetraditionally heuristicerror concealmentunits that are elements of most multimedia communication systems. In this work, we consider the reconstruction of signals encoded with a Multi-Stage Vector Quantizer andtransmitted over a noisychan- nel. The MSVQ maintains a moderate complexity and, due to its successive refinement feature, is a suitable choice for the design of layered (progressive) source codes. An approximate MMSE source decoder for MSVQ is presented and its application to re- construction of LPC parameters in MELP is analyzed. Numerical results demonstratesthe effectiveness of the proposedschemes.\",\n \"Title: Link Adaptation with Untrusted Relay Assignment: Design and Performance Analysis\\nYear: 2012\\n\\nAbstract: In this paper, a link adaptation and untrusted relay assignment (LAURA) framework for efficient and reliable wireless cooperative communications with physical layer security is proposed. Using sharp channel codes in different transmission modes, reliability for the destination and security in the presence of untrusted relays (low probability of interception) are provided through rate and power allocation. Within this framework, several schemes are designed for highly spectrally efficient link adaptation and relay selection, which involve different levels of complexity and channel state information requirement. Analytical and simulation performance evaluation of the proposed LAURA schemes are provided, which demonstrates the effectiveness of the presented designs. The results indicate that power adaptation at the source plays a critical role in spectral efficiency performance. Also, it is shown that relay selection based on the signal to noise ratio of the source to relays channels provides an interesting balance of performance and complexity within the proposed LAURA framework.\",\n \"Title: Lifetime maximized data gathering in wireless sensor networks using limited-order distributed source coding\\nYear: 2011\\n\\nAbstract: This paper addresses the problem of efficient data gathering in wireless sensor networks with a complexity constrained data gathering node. Due to the complexity constraint, the data gathering node employs an asymmetric DSC that (de)compresses the data of a given node exploiting its dependency with a limited number of other nodes. This is characterized in a DSC rate allocation structure that is referred to as limited-order DSC. Within this structure, we investigate the problem of rate allocation for the nodes to maximize the network lifetime. To this end, an algorithm is proposed that is proven optimal with polynomial complexity in terms of number of network nodes. Numerical results demonstrate that the algorithm, even with limited complexity, allows for exploiting most of the achievable compression gain.\",\n \"Title: Scalar Quantizer Design for Noisy Channel with Decoder Side Information\\nYear: 2010\\n\\nAbstract: A Wyner-Ziv Quantizer design method is introduced when the indices at the output of the encoder are transmitted over a noisy channel. The source encoder is considered as a scalar Lloyd quantizer followed by a binning and an index assignment (BIA) mapping. A modified simulated annealing based algorithm is used for BIA mapping design. A minimax solution for Wyner-Ziv problem under channel mismatch condition is also suggested when the channel is assumed to be binary symmetric channel and no information about the statistic of channel is available except the range of bit error rate. Finally the simulation results are presented which show the effectiveness of the proposed algorithm over other common alternative approaches. These results approve the proposed minimax solution too.\",\n \"Title: Soft Reconstruction of Speech in the Presence of Noise and Packet Loss\\nYear: 2007\\n\\nAbstract: Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth efficient way to combat the noisy channel degradations. In this paper, we consider soft reconstruction of speech spectrum, in GSM adaptive multirate and IS-641 vocoders, transmitted over a channel disturbed with noise and/or packet loss. Several schemes are presented which exploit different levels of intraframe and interframe residual redundancy for improved source decoding at the receiver. A packetization strategy is proposed which is matched to the presented error concealment units. For decoders that exploit the residual redundancy, extensive complexity has been a serious concern, especially as the quantizer bitrate increases . In this paper, a novel method is presented to construct reduced complexity algorithms. The proposed methodology is based on the classification of the signal domain and efficient approximation of the residual redundancy or the a priori transition probabilities. The presented schemes provide high quality error concealment solutions for code excited linear prediction (CELP) coders\",\n \"Title: Adaptive Transmission Of Qos-Guaranteed Traffic Over Mimo Wireless Links\\nYear: 2008\\n\\nAbstract: In this paper, we consider the problem of transmission of a bursty data-packet traffic over MIMO space-time diversity fading channels. Aiming at minimizing the packet loss probability due to buffer overflow at the data link layer, we propose a cross-layer analytical framework for transmission policy design which directly satisfies a packet error rate (PER) constraint at the physical layer. Particularly, we present a power and rate adaptation policy for coded M-QAM modulation schemes that are implemented in conjunction with a MIMO diversity system. To enable the transmission policy design, we use a statistical model to characterize the buffer overflow derived from a large deviations result. Numerical results demonstrate that the proposed adaptation policy significantly improves the packet-loss performance for bursty data traffic over MIMO fading channels, when compared to others adaptive solutions.\",\n \"Title: Performance Analysis of Hybrid CDMA Systems\\nYear: 2009\\n\\nAbstract: In this paper, a hybrid wireless CDMA network composed of ad hoc relays overlaid on a conventional CDMA cellular network is considered. In this setting, effective relaying helps reduce the level of interference at the base stations. The goal of this paper is to investigate the performance improvement in hybrid networks as quantified by the reduction in the probability of outage over the base stations due to interference. A new approximation method to analyze this probability and the average number of active users is introduced. Numerical results and simulations verify the extensive gain obtained by employing ad hoc relaying over the conventional CDMA networks. Moreover, results illustrate the excellent accuracy of the presented analytic approach.\",\n \"Title: Cross-Layer Link Adaptation Design for Relay Channels with Cooperative ARQ Protocol\\nYear: 2008\\n\\nAbstract: The cooperative automatic repeat request (C-ARQ) is a link layer relaying protocol which exploits the spatial diversity and allows the relay node to retransmit the source data packet to the destination, when the latter is unable to decode the source data correctly. This paper presents a cross-layer link adaptation design for C-ARQ based relay channels in which both source and relay nodes employ adaptive modulation coding and power adaptation at the physical layer. For this scenario, we first derive closed-form expressions for the system spectral efficiency and average power consumption. We then present a low complexity iterative algorithm to find the optimized adaptation solution by maximizing the spectral efficiency subject to a packet loss rate (PLR) and an average power consumption constraint. The results indicate that the proposed adaptation scheme enhances the spectral efficiency noticeably when compared to other adaptive schemes, while guaranteeing the required PLR performance.\",\n \"Title: Cross-Layer Dynamic Route Selection In Wireless Multiuser Two-Hop Networks\\nYear: 2011\\n\\nAbstract: In mobile Ad-hoc networks forwarding data through intermediate relays extends the coverage area and enhances the network throughput. Dynamic assignment of routes for data transmission from sources to destinations that is optimized based on channel conditions in a cross-layer manner could provide improved performance. We consider a general multiuser two-hop transmission, where each flow is subject to a constraint on the end-to-end buffering delay and its associated packet loss rate as a quality of service requirement. The objective is to maximize the weighted sum-rate between source destination pairs, while the QoS requirement is satisfied. We introduce two new cross-layer dynamic route selection schemes in this setting that are designed involving physical, MAC, and network layers. In cross-layer opportunistic dynamic route selection, the routes are assigned dynamically based on the instantaneous state of fading channels. In time division cross-layer dynamic route selection, the route for data transmission is scheduled based on the average quality of links. Simulation results show that our proposed cross-layer dynamic route selection schemes provide superior performance in comparison to prior art.\",\n \"Title: Online Multicasting Using Network Coding In Energy Constrained Wireless Ad Hoc Networks\\nYear: 2008\\n\\nAbstract: We consider the optimized joint design of the physical, medium access control, and network layers to maximize the lifetime of energy constrained wireless ad hoc networks for online multicast applications. We consider two types of lifetime definitions, first node failure and multicast functionality. For each definition, we investigate two energy efficient approaches of minimum total energy and min-max per node energy usage to maximize network lifetime. Using network coding at the network layer, the problem of computing multipath flow for both schemes is formulated as a linear optimization problem. Simulation results are provided assessing the effectiveness of the algorithms.\",\n \"Title: Effective capacity optimization for multiuser diversity systems with adaptive transmission.\\nYear: 2012\\n\\nAbstract: The effective capacity (EC) for a wireless system expresses the maximum arrival source rate that the system can reliably transmit over the wireless channel while fulfilling a probabilistic delay constraint. This paper presents an EC optimization for a multiuser diversity system exploiting proportional opportunistic scheduling at the medium access control layer in conjunction with adaptive modulation and coding (AMC) at the physical layer. We consider the downlink of a time-slotted multiuser system with two different types of channel state information (CSI) at the transmitter, that is, (i) full CSI, whereby each user feeds back its normalized signal-to-noise ratio to the transmitter and (ii) quantized CSI, where each user feeds back the AMC mode for transmission. For each case, we first derive the EC function of the queue service process for the individual users at the medium access control layer. We then design the AMC scheme with power control aiming at maximizing the said function subject to a target packet-error rate constraint. Both independent and identically distributed and time-correlated fading channels are considered. The results illustrate the superior performance of the proposed schemes, when compared with the previous systems such as opportunistic scheduling with single-rate transmission and round-robin scheduling with AMC. Copyright (c) 2012 John Wiley & Sons, Ltd.\",\n \"Title: Joint Adaptive Modulation Coding and Cooperative ARQ over Relay Channels-Applications to Land Mobile Satellite Communications\\nYear: 2008\\n\\nAbstract: Summary In a cooperative relay network, a relay node (R) facilitates data transmission to the destination node (D), when the latter is unable to decode the source node (S) data correctly. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive a closed form expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme. Aiming at maximizing this performance measure, we then optimize two AMC schemes for S-D and R-D links, which directly satisfy a prescribed packet loss rate constraint. As an interesting application, we also consider the problem of joint link adaptation and blockage mitigation in land mobile satellite communications (LMSC). We also present a new relay-assisted transmission protocol for LMSC, which delivers the source data to the destination via the relaying link, when the S-D channel is in outage. Numerical results indicate that the proposed schemes noticeably enhances the spectral efficiency compared to a system, which uses a conventional ARQ-AMC scheme at the S-D link, or a system which employs an optimized fixed rate cooperative-ARQ protocol.\",\n \"Title: Channel Feedback Quantization for High Data Rate MIMO Systems\\nYear: 2006\\n\\nAbstract: In this work, we study a multiple-input multiple-output (MIMO) wireless system where the channel state information is partially available at the transmitter through a feedback link. Based on singular value decomposition, the MIMO channel is split into independent sub-channels. Effective feedback of the required spatial channel information entails efficient quantization/encoding of a unitary matrix. We propose two schemes for quantizing unitary matrices via Givens rotations and examine the performance for a scenario where the rates allocated to the sub-channels are selected according to their corresponding gains. Numerical results show that the proposed schemes offer a significant performance improvement as compared to that of MIMO systems without feedback, with a negligible increase in the complexity\",\n \"Title: Modeling and Analysis of Abnormality Detection in Biomolecular Nano-Networks\\nYear: 2012\\n\\nAbstract: A scheme for detection of abnormality in molecular nano-networks is proposed. This is motivated by the fact that early diagnosis, classification and detection of diseases such as cancer play a crucial role in their successful treatment. The proposed nano-abnormality detection scheme (NADS) comprises of a two-tier network of sensor nano-machines (SNMs) in the first tier and a data gathering node (DGN) at the sink. The SNMs detect the presence of competitor cells as abnormality that is captured by variations in parameters of a nano-communications channel. In the second step, the SNMs transmit micro-scale messages over a noisy micro communications channel (MCC) to the DGN, where a decision is made upon fusing the received signals. The detection performance of each SNM is analyzed by setting up a Neyman-Pearson test. Next, taking into account the effect of the MCC, the overall performance of the proposed NADS is quantified in terms of probabilities of misdetection and false alarm. A design problem is formulated, when the optimized concentration of SNMs in a sample is obtained for a high probability of detection and a limited probability of false alarm.\",\n \"Title: Channel Sharing in Hybrid Sectorized Cellular Networks with Coverage-Limited Relays\\nYear: 2009\\n\\nAbstract: Ad hoc relaying schemes are introduced as an effective mechanism for load balancing in wireless cellular systems. The relays facilitate channel sharing between the adjacent sectors of the neighboring cells, for the calls that are originated within their coverage area. In this paper, two configurations for relay deployment in sectorized cellular systems are presented. In each case, the probability of blocking in presence of limited-coverage relays and constrained channel sharing is derived. Numerical results verify that the proposed hybrid schemes achieve significantly better grade of service compared to conventional cellular networks.\",\n \"Title: Multiple Descriptions With Symbol Based Turbo Codes Over Noisy Channels With Packet Loss: Design and Performance Analysis\\nYear: 2008\\n\\nAbstract: Channel optimized multiple description (MD) vector quantization with symbol-based turbo codes are proposed, where the decoder exploits both nonuniformity of descriptions and their dependencies. The joint source channel coding strategy is devised by setting an entropy constraint for quantizer design, which together with the MD index assignment (IA), control the level of redundancy at the MD source ...\",\n \"Title: Discrete Rate Interfering Cognitive Link Adaptation Design with Primary Link Spectral Efficiency Provisioning.\\nYear: 2011\\n\\nAbstract: We consider a primary and a cognitive user transmitting over a wireless fading interference channel. A discrete rate link adaptation scheme is proposed to maximize the average spectral efficiency of the cognitive radio, while a minimum average spectral efficiency for the primary user is provisioned. The discrete rate scheme for interfering transmission is devised based on two sets of modulation an...\",\n \"Title: Joint adaptive modulation-coding and cooperative ARQ for wireless relay networks\\nYear: 2008\\n\\nAbstract: This paper presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive an exact closed form expression for the spectral efficiency of the proposed joint AMC - cooperative ARQ scheme. Aiming at maximizing this system performance measure, we then optimize an AMC scheme which directly satisfies a prescribed packet loss rate constraint at the data-link layer. The results indicate that utilizing cooperative ARQ as a retransmission strategy, noticeably enhances the spectral efficiency compared with the system that employs AMC alone at the physical layer. Moreover, the proposed adaptive rate cooperative ARQ scheme outperforms the fixed rate counterpart when the transmission modes at the source and relay are chosen based on the channel statistics. This in turn quantifies the possible gain achieved by joint design of AMC and ARQ in wireless relay networks.\",\n \"Title: Delay Performance Optimization for Multiuser Diversity Systems with Bursty-Traffic and Heterogeneous Wireless Links\\nYear: 2009\\n\\nAbstract: This paper presents a cross-layer approach for optimizing the delay performance of a multiuser diversity system with heterogeneous block-fading channels and a delay-sensitive bursty-traffic. We consider the downlink of a time-slotted multiuser system employing opportunistic scheduling with fair performance at the medium access (MAC) layer and adaptive modulation and coding (AMC) with power control at the physical layer. Assuming individual user buffers which temporarily store the arrival traffic of users at the MAC layer, we first present a large deviations based statistical model to evaluate the delay-bound violation of packets in the user buffers. Aiming at minimizing the delay probability of the individual users, we then optimize the AMC and power control module subject to a target packet-error rate constraint. In the case of a quantized feedback channel, we also present a constant-power AMC based opportunistic scheduling scheme. Numerical and simulation results are provided to evaluate the delay performance of the proposed adaptation schemes in a multiuser setup.\",\n \"Title: Spectral Efficiency Optimized Adaptive Transmission for Cognitive Radios in an Interference Channel\\nYear: 2009\\n\\nAbstract: In this paper, we consider a primary and a cognitive user transmitting over a\\nwireless fading interference channel. The primary user transmits with a\\nconstant power and utilizes an adaptive modulation and coding (AMC) scheme\\nsatisfying a bit error rate requirement. We propose a link adaptation scheme to\\nmaximize the average spectral efficiency of the cognitive radio, while a\\nminimum required spectral efficiency for the primary user is provisioned. The\\nresulting problem is constrained to also satisfy a bit error rate requirement\\nand a power constraint for the cognitive link. The AMC mode selection and power\\ncontrol at the cognitive transmitter is optimized based on the scaled signal to\\nnoise plus interference ratio feedback of both links. The problem is then cast\\nas a nonlinear discrete optimization problem for which a fast and efficient\\nsuboptimum solution is presented. We also present a scheme with rate adaption\\nand a constant power. An important characteristic of the proposed schemes is\\nthat no negotiation between the users is required. Comparisons with underlay\\nand interweave approaches to cognitive radio with adaptive transmission\\ndemonstrate the efficiency of the proposed solutions.\",\n \"Title: Block Network Error Control Codes and Syndrome-based Complete Maximum Likelihood Decoding\\nYear: 2008\\n\\nAbstract: In this paper, network error control coding is studied for robust and efficient multicast in a directed acyclic network with imperfect links. The block network error control coding framework, BNEC, is presented and the capability of the scheme to correct a mixture of symbol errors and packet erasures and to detect symbol errors is studied. The idea of syndrome-based decoding and error detection is introduced for BNEC, which removes the effect of input data and hence decreases the complexity. Next, an efficient three- stage syndrome-based BNEC decoding scheme for network error correction is proposed, in which prior to finding the error values, the position of the edge errors are identified based on the error spaces at the receivers. In addition to bounded-distance decoding schemes for error correction up to the refined Singleton bound, a complete decoding scheme for BNEC is also introduced. Specifically, it is shown that using the proposed syndrome-based complete decoding, a network error correcting code with redundancy order δt for receiver t, can correct δt-1 random additive errors with a probability sufficiently close to 1, if the field size is sufficiently large. Also, a complete maximum likelihood decoding scheme for BNEC is proposed. As the probability of error in different network edges is not equal in general, and given the equivalency of certain edge errors within the network at a particular receiver, the number of edge errors, assessed in the refined Singleton bound, is not a sufficient statistic for ML decoding.\",\n \"Title: Robust Transmission of Multistage Vector Quantized Sources Over Noisy Communication Channels—Applications to MELP Speech Codec\\nYear: 2006\\n\\nAbstract: Joint source-channel coding is an effective approach for the design of bandwidth efficient and error resilient communication systems with manageable complexity. An interesting research direction within this framework is the design of source decoders that exploit the residual redundancy for effective signal reconstruction at the receiver. Such source decoders are expected to replace the traditional...\",\n \"Title: Performance analysis of ad-hoc routing in heterogeneous clustered multi-hop wireless networks.\\nYear: 2015\\n\\nAbstract: This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, hop-by-hop routing is known as an efficient decentralized routing algorithm which selects the best relay node in each hop using local channel state information. In this article, we combine hop-by-hop routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Numerical results are provided to validate the correctness of the presented analyses.\",\n \"Title: Performance Analysis of Ad-Hoc Routing in Clustered Multi-hop Wireless Networks.\\nYear: 2014\\n\\nAbstract: This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, ad-hoc routing is known as an efficient decentralized routing algorithm which selects the best relay node on a hop-by-hop basis using local channel state information. In this article, we combine ad-hoc routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Simulation results are provided to validate the correctness of the presented analyses.\",\n \"Title: Design of LDPC Codes Robust to Noisy Message-Passing Decoding.\\nYear: 2015\\n\\nAbstract: We address noisy message-passing decoding of lowdensity parity-check (LDPC) codes over additive white Gaussian noise channels. Message-passing decoders in which certain processing units iteratively exchange messages are common for decoding LDPC codes. The exchanged messages are in general subject to internal noise in hardware implementation of these decoders. We model the internal decoder noise as additive white Gaussian noise (AWGN) degrading exchanged messages. Using Gaussian approximation of the exchanged messages, we perform a two-dimensional density evolution analysis for the noisy LDPC decoder. This makes it possible to track both the mean, and the variance of the exchanged message densities, and hence, to quantify the threshold of the LDPC code in the presence of internal decoder noise. The numerical and simulation results are presented that quantify the performance loss due to the internal decoder noise. To partially compensate this performance loss, we propose a simple method, based on EXIT chart analysis, to design robust irregular LDPC codes. The simulation results indicate that the designed codes can indeed compensate part of the performance loss due to the internal decoder noise.\",\n \"Title: On Capacity and Capacity per Unit Cost of Gaussian Multiple Access Channel with Peak Power Constraints.\\nYear: 2014\\n\\nAbstract: This paper investigates the capacity and capacity per unit cost of Gaussian multiple access-channel (GMAC) with peak power constraints. We first devise an approach based on Blahut-Arimoto Algorithm to numerically optimize the sum rate and quantify the corresponding input distributions. The results reveal that in the case with identical peak power constraints, the user with higher SNR is to have a symmetric antipodal input distribution for all values of noise variance. Next, we analytically derive and characterize an achievable rate region for the capacity in cases with small peak power constraints, which coincides with the capacity in a certain scenario. The capacity per unit cost is of interest in low power regimes and is a target performance measure in energy efficient communications. In this work, we derive the capacity per unit cost of additive white Gaussian channel and GMAC with peak power constraints. The results in case of GMAC demonstrate that the capacity per unit cost is obtained using antipodal signaling for both users and is independent of users rate ratio. We characterize the optimized transmission strategies obtained for capacity and capacity per unit cost with peak-power constraint in detail and specifically in contrast to the settings with average-power constraints.\",\n \"Title: Distributed Cross-layer Dynamic Route Selection in Wireless Multiuser Multihop Networks.\\nYear: 2014\\n\\nAbstract: In wireless ad-hoc networks, forwarding data through intermediate relays extends the coverage area and enhances the network throughput. We consider a general wireless multiuser multihop transmission, where each data flow is subject to a constraint on the end-to-end buffering delay and the associated packet drop rate as a quality of service (QoS) requirement. The objective is to maximize the weighted sum-rate between source destination pairs, while the corresponding QoS requirements are satisfied. We introduce two new distributed cross-layer dynamic route selection schemes in this setting that are designed involving physical, MAC, and network layers. In the proposed opportunistic cross-layer dynamic route selection scheme, routes are assigned dynamically based on the state of network nodes' buffers and the instantaneous state of fading channels. In the same setting, the proposed time division cross layer dynamic route selection scheme utilizes the average quality of channels instead for more efficient implementation. Detailed results and comparisons are provided, which demonstrate the superior performance of the proposed cross-layer dynamic route selection schemes.\",\n \"Title: A key pre-distribution scheme based on multiple block codes for wireless sensor networks\\nYear: 2014\\n\\nAbstract: A key pre-distribution scheme (KPS) based on multiple codewords of block codes is presented for wireless sensor networks. The connectivity and security of the proposed KPS, quantified in terms of probabilities of sharing common keys for communications of pairs of nodes and their resilience against colluding nodes, are analytically assessed. The analysis is applicable to both linear and nonlinear codes and is simplified in the case of maximum distance separable codes. It is shown that the multiplicity of codes significantly enhances the security and connectivity of KPS at the cost of a modest increase of the nodes storage. Numerical and simulation results are provided, which sheds light on the effect of system parameters of the proposed KPS on its complexity and performance. Specifically, it is shown that the probability of resilience of secure pairs against collusion of other nodes only reduces slowly as the number of colluding nodes increase.\",\n \"Title: A matrix completion approach to linear index coding problem\\nYear: 2014\\n\\nAbstract: In this paper, a general algorithm is proposed for rate analysis and code design of linear index coding problems. Specifically a solution for minimum rank matrix completion problem over finite fields representing the linear index coding problem is devised in order to find the optimum transmission rate given vector length and size of the field. The new approach can be applied to both scalar and vector linear index coding.\",\n \"Title: Multi-level Distributed Arithmetic Coding with Nested Lattice Quantization\\nYear: 2014\\n\\nAbstract: In this paper, a scheme based on 1-D nested lattice quantization followed by multi-level distributed arithmetic coding (MLDAC) as the Slepian-Wolf (SW) code is proposed for the lossy source coding of continuous sources. This system can be employed in distributed video and image coding applications. The output of the quantizer is first converted to binary, and then the SW coding is applied on each bit plane. An efficient algorithm for joint decoding of bit planes at the decoder is proposed, which exploits the dependency of the bit planes with each other and the side-information available at the decoder. Also, a methodology for rate allocation among the bit planes is presented. The quantization parameters are designed to improve the end-to-end system performance based on its overall rate-distortion function taking into account both the distortions due to quantization and imperfect practical Slepian-Wolf coding. The simulation results demonstrate the effectiveness of the proposed MLDAC with the lattice quantization.\",\n \"Title: Quantization of LSF parameters using a trellis modeling\\nYear: 2003\\n\\nAbstract: An efficient block-based trellis quantization (BTQ) scheme is proposed for the quantization of the line spectral frequencies (LSF) in speech coding applications. The scheme is based on the modeling of the LSF intraframe dependencies with a trellis structure. The ordering property and the fact that LSF parameters are bounded within a range is explicitly incorporated in the trellis model. BTQ search and design algorithms are discussed and an efficient algorithm for the index generation (finding the index of a path in the trellis) is presented. Also the sequential vector decorrelation technique is presented to effectively exploit the intraframe correlation of LSF parameters within the trellis. Based on the proposed block-based trellis quantizer, two intraframe schemes and one interframe scheme are proposed. Comparisons to the split-VQ, the trellis coded quantization of LSF parameters, and the multi-stage VQ, as well as the interframe scheme used in IS-641 EFRC and the GSM AMR codec are provided. These results demonstrate that the proposed BTQ schemes outperform the above systems.\",\n \"Title: Reconstruction of predictively encoded signals over noisy channels using a sequence MMSE decoder\\nYear: 2004\\n\\nAbstract: Abstract Inthis work, we considertheproblem ofdecoding apredictively encodedsignal over anoisy channel whenthereisaresidualredundancy(capturedbya ∞-orderMarkovmodel)inthesequenceoftransmitted data. Ourobjectiveistominimizethemeansquarederrorinthereconstructionoftheoriginalsignal(input to the predictive source coder). The problem is formulated and solved through Minimum Mean Squared Error(MMSE)decodingofasequenceofsamplesoveramemorylessnoisychannel. Therelatedprevious works include several MAP and MMSE-based decoders. The MAP-based approaches are suboptimal when the performance criterion is the mean squared error. On the other hand, the previously known MMSE-basedapproachesaresuboptimalsincetheyaredesignedtoe‐cientlyreconstructthedatasamples received (the prediction residues) rather than the original signal. The proposed scheme,is setup by modeling the source coder produced symbols and their redundancy with a trellis structure. Methods are presented to optimize the solutions in terms of complexity. Numerical results and comparisons are provided which demonstrate the efiectiveness of the proposed techniques. Keywords Jointsourcechannelcoding residualredundancies sourcedecoding MMSEestimation MAPdetec-\",\n \"Title: Queuing with Adaptive Modulation over MIMO Wireless Links for Deadline Constrained Traffic: Cross-Layer Analysis and Design\\nYear: 2007\\n\\nAbstract: Abstract-In this paper, we consider a deadline constrained traffic and ,analyze the joint effects of packet ,queuing and adaptive modulation (AM) for packet transmission in MIMO systems. We present a general analytical procedure, and derive the achievable delay-bound violation probability, the packet loss rate, and the average throughput of AM in MIMO wireless links employing orthogonal space time block coding (STBC) over Nakagami fading channels. In the proposed analytical procedure, weuse,statistical delay-bound for deadline constrained traffic based,on the ,effective bandwidth ,theory. Based on our performance analysis, we propose a cross-layer design, which selects the optimal target packet error rate of AM at the physical layer, to minimize the packet loss rate and maximize the average throughput, when combined with packet queuing at the data link layer. Numerical ,results demonstrate ,that ,the ,system performance depends on various parameters, and show the performance,gain due to cross-layer design. We also ,discuss briefly possible applications of our proposed modeling to quality of service guarantee in multiuser scenarios.\",\n \"Title: A Decentralized Approach to Network Coding Based on Learning\\nYear: 2007\\n\\nAbstract: In this paper, we introduce a new efficient method based on reinforcement learning to construct linear network codes, referred to as the Reinforcement Learning Network Code (RLNC) design. We will make use of the market theory concepts in the learning section of the algorithm. The learning approach results in a smart random search and we demonstrate that the proposed algorithm is decentralized, and polynomial time complex. The RLNC algorithm constructs network codes faster than the random method of (4) with the same complexity order, especially in large networks with small field sizes. It is also shown that the algorithm can re-construct the network code in the presence of link failures with a small complexity and without previously being aware of error patterns even in very large networks. Further extension to achieve the objective of decreasing the number of encoding nodes in a network is discussed.\",\n \"Title: Robust Network Coding in the Presence of Link Failure Using a Multicast Rate-Diversity Trade off\\nYear: 2007\\n\\nAbstract: We introduce a centralized joint network- channel coding scheme for maximized throughput and increased robustness against link failure in a communication network. We introduce RNC1(h,k) to multicast k independent data in a directed and acyclic network with capacity h, h k ≤ . The redundancy through path diversity increases the resistance of the network against link failure. An improved version of RNC1, RNC2(h,k), is introduced to guarantee the rate k for h-k flow failures. The proposed schemes exploit the network structure for code design, which results in a manageable design complexity.\",\n \"Title: Optimizing Delay Performance over MIMO Fading Channels with Adaptive Transmission\\nYear: 2008\\n\\nAbstract: In this paper, we consider the problem of transmitting a delay-sensitive and bursty traffic over a time- varying MIMO Nakagami-ra fading channel, and optimize the delay performance of packet queuing at the data link layer. We use a statistical model to characterize the packet delay derived from a known large deviations result, and allows for analytical insights into transmission policy design. We derive power and rate adaptation policies for coded M-QAM modulation schemes that are implemented in conjunction with a MIMO diversity system; such that the packet delay probability is minimized subject to a prescribed channel packet error rate constraint. This is also equivalent to minimizing the system packet loss rate. The proposed adaptation policies depend not only on channel conditions but also on the quality of service performance at the data link layer. Numerical results show that the proposed cross- layer adaptation policies significantly improve the delay performance for delay-sensitive bursty traffic over MIMO fading channels, when compared to others adaptive solutions.\",\n \"Title: Adaptive transmission policy design for delay-sensitive and bursty packet traffic over wireless fading channels\\nYear: 2009\\n\\nAbstract: In this paper, we consider the problem of transmission of a delay-sensitive and bursty traffic source over a time-varying Nakagami-m fading channel in a cross-layer optimization framework. Aiming at minimizing the packet delay due to queuing at the data link layer, we present power and rate adaptation policies for coded M-QAM modulation schemes, which guarantee a prescribed channel packet error rate constraint. This is also equivalent to minimizing the system packet loss rate. The proposed adaptation policies are derived both for block and correlated channel fading scenarios. To enable the transmission policy design, we use a statistical model to characterize the packet delay derived from a known result of large deviations theory. Considering the error resolution capability of the automatic repeat request protocol, we then provide the appropriate analytical tools to incorporate the effect of packet retransmission in the proposed optimization framework for transmission policy design. The results show that the proposed adaptation policies compared to others adaptive solutions, significantly improve the delay and throughput performance for delay-sensitive bursty traffic over time-varying fading channels.\",\n \"Title: A flexible rate slepian-wolf code construction\\nYear: 2009\\n\\nAbstract: A flexible rate Slepian-Wolf (SW) code is constructed, which is vital for wireless sensor network applications. The proposed solution is based on an efficient and practical algorithm to compute the syndrome of the rate-compatible convolutional codes (RCPC). Using this algorithm, there is no need to compute the syndrome of punctured version of the mother code for each puncturing matrix, which is complex. Instead, the syndrome of the punctured code is the punctured version of the syndrome of the mother code using the same pattern of puncturing. The algorithm is general for all convolutional codes in Zq. The strategy is also generalized for parallel and serial concatenated convolutional codes. For the cases, where the dependencies among sources are modeled as a virtual discrete channel, a simplified decoding scheme is suggested. This method is generalized to achieve all points on the SW boundary using a simple code design technique. Simulation results demonstrate the performance and effectiveness of the proposed methods.\",\n \"Title: Link adaptation for physical layer security over wireless fading channels\\nYear: 2012\\n\\nAbstract: A secure link adaptation framework is proposed, which exploits the inherent fluctuations of wireless fading channels for high-performance communications and physical layer security in the presence of an eavesdropper. The authors use very sharp channel codes intended for reliability and demonstrate that they also provide security, when successfully incorporated in the link adaptation design framework and the security constraint is not very stringent. Two scenarios are considered in which the transmitter has access to the eavesdropper channel state information either instantaneously or statistically. The proposed secure link adaptation framework is formulated to maximise the spectral efficiency of the communication, whereas both reliability and security constraints are provisioned. Different designs are considered when the security constraint is quantified by instantaneous bit error rate (BER), average BER or leakage probability. For the problem with instantaneous BER constraint, an efficient analytical solution and a numerical solution are presented. A closed-form analytical solution is also provided for secure link adaptation with average BER constraint, whereas the problem with the leakage constraint is tackled numerically. Extensive results and detailed analysis are provided to draw insights on the effects of different design parameters on the performance.\",\n \"Title: Multi-Mode Nested Quantization in Presence of Uncertain Side Information and Feedback\\nYear: 2013\\n\\nAbstract: In this paper, the problem of uniform quantization for the Wyner-Ziv (WZ) problem in presence of uncertain side information at the encoder is addressed. The uncertain side information problem arises in data compression with side information (SI) when the joint probability distribution of source and SI is not (fully) known at the encoder. The uncertainty is due to the time varying nature of the dependency of source and SI in settings such as wireless sensor networks and distributed video coding. In this paper, a solution is proposed which consists of a multi-mode WZ encoder in conjunction with a carefully designed feedback scheme from the decoder. Each encoder mode is associated with a uniform nested quantizer. In this framework, the quantization parameters, the feedback scheme, and the source coding rate are jointly optimized to minimize the average rate or distortion. Two distinct schemes with adaptive or fixed transmission rate are proposed. Simulation results are provided which demonstrate the effectiveness of the presented solutions and assess the effect of different design parameters including the number of modes (feedback rate) on the performance.\",\n \"Title: Delay-Limited Source and Channel Coding of Quasi-Stationary Sources over Block Fading Channels: Design and Scaling Laws\\nYear: 2012\\n\\nAbstract: In this paper, delay-limited transmission of quasi-stationary sources over block fading channels is considered. Considering distortion outage probability as the performance measure, two source and channel coding schemes with power adaptive transmission are presented. The first one is optimized for fixed rate transmission, and hence enjoys simplicity of implementation. The second one is a high performance scheme, which also benefits from optimized rate adaptation with respect to source and channel states. In high SNR regime, the performance scaling laws in terms of outage distortion exponent and asymptotic outage distortion gain are derived, where two schemes with fixed transmission power and adaptive or optimized fixed rates are considered as benchmarks for comparisons. Various analytical and numerical results are provided which demonstrate a superior performance for source and channel optimized rate and power adaptive scheme. It is also observed that from a distortion outage perspective, the fixed rate adaptive power scheme substantially outperforms an adaptive rate fixed power scheme for delay-limited transmission of quasi-stationary sources over wireless block fading channels. The effect of the characteristics of the quasi-stationary source on performance, and the implication of the results for transmission of stationary sources are also investigated.\",\n \"Title: A Type II Hybrid ARQ Protocol with Adaptive Modulation and Coding for Time-Correlated Fading Channels: Analysis and Design\\nYear: 2010\\n\\nAbstract: This paper presents performance analysis and cross-layer design approaches for hybrid ARQ (HARQ) protocol in wireless networks which employ adaptive modulation and coding (AMC) at the physical layer and are subject to time-correlated fading channels. Utilizing a Markov channel model which accounts for the temporal correlation in successive parity transmissions by the adaptive rate HARQ protocol, we derive the system throughput and the packet loss probability based on a rate compatible punctured convolutional (RCPC) code family. As an application, we then present a cross-layer AMC design which takes into account the performance gain of the HARQ protocol at the link layer. The results illustrate that including AMC in the HARQ protocol leads to a substantial throughput gain, but the channel correlation strongly diminishes the performance of the HARQ protocol in terms of throughput and packet loss rate.\",\n \"Title: Information Rates of ASK-Based Molecular Communication in Fluid Media.\\nYear: 2015\\n\\nAbstract: This paper studies the capacity of molecular communications in fluid media, where the information is encoded in the number of transmitted molecules in a time-slot (amplitude shift keying). The propagation of molecules is governed by random Brownian motion and the communication is in general subject to intersymbol interference (ISI). We first consider the case where ISI is negligible and analyze th...\",\n \"Title: Bounds on the Capacity of ASK Molecular Communication Channels with ISI\\nYear: 2015\\n\\nAbstract: There are now several works on the use of the additive inverse Gaussian noise (AIGN) model for the random transit time in molecular communication (MC) channels. The randomness invariably causes inter- symbol interference (ISI) in MC, an issue largely ignored or simplified. In this paper we derive an upper bound and two lower bounds for MC based on amplitude shift keying (ASK) in presence of ISI. The Blahut-Arimoto algorithm (BAA) is modified to find the input distribution of transmitted symbols to maximize the lower bounds. Our results show that over wide parameter values the bound are close.\",\n \"Title: Constellation Shaping and LDPC Coding in a Bidirectional Full Duplex Communication.\\nYear: 2015\\n\\nAbstract: We investigate the ability of the physical layer approaches of constellation shaping and forward error correction to enhance the performance of full duplex (FD) wireless radio systems. We use low density parity check and optimized shaping codes to transmit non-equiprobable constellation points from an amplitude phase shift keying modulation with imperfect power amplifier and in the presence of FD residual self interference. A simple approach to the design of optimized shaping codes for a given signal to noise ratio and residual self interference power is presented. Simulation results show that a FD transceiver with bit interleaved coded modulation, optimized shaping and iterative demodulation and decoding noticeably improves the performance in comparison to the same system without constellation shaping.\",\n \"Title: Distortion-Power Tradeoffs in Quasi-Stationary Source Transmission Over Delay and Buffer Limited Block Fading Channels.\\nYear: 2016\\n\\nAbstract: This paper investigates distortion-power tradeoffs in transmission of quasi-stationary sources over delay and buffer limited block fading channels by studying encoder and decoder buffering techniques to smooth out the source and channel variations. Four source and channel coding schemes that consider buffer and power constraints are presented to minimize the reconstructed source distortion. The fi...\",\n \"Title: RCFD: A Novel Channel Access Scheme for Full-Duplex Wireless Networks Based on Contention in Time and Frequency Domains.\\nYear: 2018\\n\\nAbstract: In the last years, the advancements in signal processing and integrated circuits technology allowed several research groups to develop working prototypes of in-band full-duplex wireless systems. The introduction of such a revolutionary concept is promising in terms of increasing network performance, but at the same time poses several new challenges, especially at the MAC layer. Consequently, innov...\",\n \"Title: Resource Allocation In Ofdma Networks With Half-Duplex And Imperfect Full-Duplex Users\\nYear: 2016\\n\\nAbstract: Recent studies indicate the feasibility of in-band fullduplex (FD) wireless communications, where a wireless radio transmits and receives simultaneously in the same band. Due to its potential to increase the capacity, analyzing the performance of a cellular network that contains full-duplex devices is crucial. In this paper, we consider maximizing the weighted sum-rate of downlink and uplink of a single cell OFDMA network which consists of an imperfect FD base-station (BS) and a mixture of half-duplex and imperfect full-duplex mobile users. To this end, the joint problem of sub-channel assignment and power allocation is investigated and a two-step solution is proposed. A heuristic algorithm to allocate each sub-channel to a pair of downlink and uplink users with polynomial complexity is presented. The power allocation problem is convexified based on the difference of two concave functions approach, for which an iterative solution is obtained. Simulation results demonstrate that when all the users and the BS are perfect FD nodes the network throughput could be doubled, Otherwise, the performance improvement is limited by the inter-node interference and the self-interference. We also investigate the effect of the self-interference cancellation capability and the percentage of FD users on the network performance in both indoor and outdoor scenarios.\",\n \"Title: RCFD: A Frequency Based Channel Access Scheme for Full Duplex Wireless Networks.\\nYear: 2016\\n\\nAbstract: Recently, several working implementations of in--band full--duplex wireless systems have been presented, where the same node can transmit and receive simultaneously in the same frequency band. The introduction of such a possibility at the physical layer could lead to improved performance but also poses several challenges at the MAC layer. In this paper, an innovative mechanism of channel contention in full--duplex OFDM wireless networks is proposed. This strategy is able to ensure efficient transmission scheduling with the result of avoiding collisions and effectively exploiting full--duplex opportunities. As a consequence, considerable performance improvements are observed with respect to standard and state--of--the--art MAC protocols for wireless networks, as highlighted by extensive simulations performed in ad hoc wireless networks with varying number of nodes.\",\n \"Title: Abnormality Detection in Correlated Gaussian Molecular Nano-Networks: Design and Analysis.\\nYear: 2016\\n\\nAbstract: A nano-abnormality detection scheme (NADS) in molecular nano-networks is studied. This is motivated by the fact that early detection of diseases such as cancer plays a crucial role in their successful treatment. The proposed NADS is in fact a two-tier network of sensor nano-machines (SNMs) in the first tier and a data-gathering node (DGN) at the sink. The SNMs detect the presence of competitor cel...\",\n \"Title: Statistical Qos Analysis Of Full Duplex And Half Duplex Heterogeneous Cellular Networks\\nYear: 2016\\n\\nAbstract: In this paper, statistical Quality of Service provisioning in next generation heterogeneous mobile cellular networks is investigated. To this aim, any active entity of the cellular network is regarded as a queuing system, whose statistical QoS requirements depend on the specific application. In this context, by quantifying the performance in terms of effective capacity, we introduce a lower bound for the system performance that facilitates an efficient analysis. We exploit this analytical framework to give insights about the possible improvement of the statistical QoS experienced by the users if the current heterogeneous cellular network architecture migrates from a Half Duplex to a Full Duplex mode of operation. Numerical results and analysis are provided, where the network is modeled as a Matern point processes with a hard core distance. The results demonstrate the accuracy and computational efficiency of the proposed scheme, especially in large scale wireless systems.\",\n \"Title: Analysis of key generation rate from wireless channel in in-band full-duplex communications\\nYear: 2016\\n\\nAbstract: In this paper, the impact of in-band full-duplex (IBFD) wireless communications on secret key generation via physical layer channel state information is investigated. A key generation strategy for IBFD wireless devices to increase the rate of generated secret keys over multipath fading channels is proposed. Conventionally, due to the half-duplex (HD) constraint on wireless transmissions, sensing simultaneous reciprocal channel measurements is not possible, which leads to a degraded key generation rate. However, with the advent of IBFD wireless devices, the legitimate nodes can sense the shared wireless link simultaneously at the possible cost of a self-interference (SI) channel estimation and some residual self-interference (RSI). As we demonstrate, with HD correlated observations the key rate is upper bounded by a constant, while with IBFD the key rate is only limited by the SI cancellation performance and is in general greater than that of its HD counterpart. Our analysis shows that with reasonable levels of SI cancellation, in the high SNR regime the key rate of IBFD is much higher, while in low SNRs, the HD system performs better. Finally, the key rate loss due to the overhead imposed by the SI channel estimation phase is discussed.\",\n \"Title: Automatic fault detection and diagnosis in cellular networks using operations support systems data.\\nYear: 2016\\n\\nAbstract: Self-Healing is one of the key important functionalities in self-organizing mobile communication networks. Despite its importance, self-healing has yet to receive a deserving research attention in the literature. This paper considers important quality indicators in a live mobile communications network and presents an automatic unified detection and diagnosis framework to identify root causes of faults occurred in the network. The proposed solution relies on unsupervised clustering of both traffic and signaling (continuous) key performance indicators for diagnosis. Hence, it is immune to the human error in the modeling phase. It also allows to effectively encapsulate experts knowledge as they relate clusters to root causes in the design phase. Detailed analysis of fault detection, the clustering schemes and the diagnosis are provided using operations support systems data of a real cellular network.\",\n \"Title: Analysis of Statistical QoS in Half Duplex and Full Duplex Dense Heterogeneous Cellular Networks.\\nYear: 2017\\n\\nAbstract: Statistical QoS provisioning as an important performance metric in analyzing next generation mobile cellular network, aka 5G, is investigated. In this context, by quantifying the performance in terms of the effective capacity, we introduce a lower bound for the system performance that facilitates an efficient analysis. Based on the proposed lower bound, which is mainly built on a per resource block analysis, we build a basic mathematical framework to analyze effective capacity in an ultra dense heterogeneous cellular network. We use our proposed scalable approach to give insights about the possible enhancements of the statistical QoS experienced by the end users if heterogeneous cellular networks migrate from a conventional half duplex to an imperfect full duplex mode of operation. Numerical results and analysis are provided, where the network is modeled as a Matern point process. The results demonstrate the accuracy and computational efficiency of the proposed scheme, especially in large scale wireless systems. Moreover, the minimum level of self interference cancellation for the full duplex system to start outperforming its half duplex counterpart is investigated.\",\n \"Title: Resource Allocation in Heterogenous Full-duplex OFDMA Networks: Design and Analysis.\\nYear: 2018\\n\\nAbstract: Recent studies indicate the feasibility of full-duplex (FD) bidirectional wireless communications. Due to its potential to increase the capacity, analyzing the performance of a cellular network that contains full-duplex devices is crucial. In this paper, we consider maximizing the weighted sum-rate of downlink and uplink of an FD heterogeneous OFDMA network where each cell consists of an imperfect FD base-station (BS) and a mixture of half-duplex and imperfect full-duplex mobile users. To this end, first, the joint problem of sub-channel assignment and power allocation for a single cell network is investigated. Then, the proposed algorithms are extended for solving the optimization problem for an FD heterogeneous network in which intra-cell and inter-cell interferences are taken into account. Simulation results demonstrate that in a single cell network, when all the users and the BSs are perfect FD nodes, the network throughput could be doubled. Otherwise, the performance improvement is limited by the inter-cell interference, inter-node interference, and self-interference. We also investigate the effect of the percentage of FD users on the network performance in both indoor and outdoor scenarios, and analyze the effect of the self-interference cancellation capability of the FD nodes on the network performance.\",\n \"Title: Exact Assessment of the Delay-Rate Tradeoff in Ergodic Interference Alignment.\\nYear: 2018\\n\\nAbstract: In order to increase the network capacity and fulfill the Quality of Service requirements in multi-user wireless networks, interference alignment (IA) has been proposed. Subsequently, ergodic IA was introduced as a promising scheme to achieve a degrees-of-freedom metric equal to (1/2), at the expense of additional delay. In this letter, we study the delay-rate trade-off in ergodic IA and exactly c...\",\n \"Title: Analysis of distributed ADMM algorithm for consensus optimisation over lossy networks.\\nYear: 2018\\n\\nAbstract: Alternating direction method of multipliers (ADMM) is a popular convex optimisation algorithm, which is implemented in a distributed manner. Applying this algorithm to consensus optimisation problem, where a number of agents cooperatively try to solve an optimisation problem using locally available data, leads to a fully distributed algorithm which relies on local computations and communication be...\",\n \"Title: Analysis of Distributed ADMM Algorithm for Consensus Optimization in Presence of Node Error.\\nYear: 2019\\n\\nAbstract: Alternating direction method of multipliers (ADMM) is a popular convex optimization algorithm, which can be employed for solving distributed consensus optimization problems. In this setting, agents locally estimate the optimal solution of an optimization problem and exchange messages with their neighbors over a connected network. The distributed algorithms are typically exposed to different types ...\",\n \"Title: Neuronal Synchronization Can Control the Energy Efficiency of Inter-Spike Interval Coding\\nYear: 2018\\n\\nAbstract: The role of synchronous firing in sensory coding and cognition remains controversial. While studies, focusing on its mechanistic consequences in attentional tasks, suggest that synchronization dynamically boosts sensory processing, others failed to find significant synchronization in such tasks. We attempt to understand both lines of evidence within a coherent theoretical framework. We conceptualize synchronization as an independent control parameter to study how the postsynaptic neuron transmits the average firing activity of a presynaptic population, in the presence of synchronization. We apply the Berger-Levy theory of energy efficient information transmission to interpret simulations of a Hodgkin-Huxley-type postsynaptic neuron model, where we varied independently the firing rate and synchronization level in the presynaptic population. We find that for a fixed presynaptic firing rate the simulated postsynaptic interspike interval distribution depends on the synchronization level and is well-described by a generalized extreme value distribution. For synchronization levels of 15% to 50%, we find that the optimal distribution of presynaptic firing rate, maximizing the mutual information per unit cost, is maximized at ~30% synchronization level. These results suggest that the statistics and energy efficiency of neuronal communication channels, through which the input rate is communicated, can be dynamically adapted by the synchronization level.\",\n \"Title: How to Query an Oracle? Efficient Strategies to Label Data\\nYear: 2022\\n\\nAbstract: We consider the basic problem of querying an expert oracle for labeling a dataset in machine learning. This is typically an expensive and time consuming process and therefore, we seek ways to do so efficiently. The conventional approach involves comparing each sample with (the representative of) each class to find a match. In a setting with \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$N$</tex-math></inline-formula>\\n equally likely classes, this involves \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$N/2$</tex-math></inline-formula>\\n pairwise comparisons (queries per sample) on average. We consider a \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$k$</tex-math></inline-formula>\\n-ary query scheme with \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$k\\\\geq 2$</tex-math></inline-formula>\\n samples in a query that identifies (dis)similar items in the set while effectively exploiting the associated transitive relations. We present a randomized batch algorithm that operates on a round-by-round basis to label the samples and achieves a query rate of \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$O(\\\\frac{N}{k^2})$</tex-math></inline-formula>\\n. In addition, we present an adaptive greedy query scheme, which achieves an average rate of \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$\\\\approx 0.2N$</tex-math></inline-formula>\\n queries per sample with triplet queries. For the proposed algorithms, we investigate the query rate performance analytically and with simulations. Empirical studies suggest that each triplet query takes an expert at most 50% more time compared with a pairwise query, indicating the effectiveness of the proposed \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$k$</tex-math></inline-formula>\\n-ary query schemes. We generalize the analyses to nonuniform class distributions when possible.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":54,"string":"54"}}},{"rowIdx":55,"cells":{"question_id":{"kind":"string","value":"Rong Zhu"},"question":{"kind":"string","value":"Generate an abstract for the title \"A two-dimensional flow sensor with integrated micro thermal sensing elements and a back propagation neural network.\" using the following items: Flow sensor, direction sensitivity, data fusion algorithm, micromachining techniques, measurement accuracy."},"answer":{"kind":"string","value":"This paper demonstrates a novel flow sensor with two-dimensional 360 direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360 direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s-30 m/s and the measurement accuracy of flow direction angle reaches 1.9 degrees in the range of 360 degrees."},"correct_answer":{"kind":"string","value":"This paper demonstrates a novel flow sensor with two-dimensional 360 direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360 direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s-30 m/s and the measurement accuracy of flow direction angle reaches 1.9 degrees in the range of 360 degrees."},"documents":{"kind":"list like","value":["Title: A Novel Image Classification Method Based on Double Manifold Learning\nYear: 2010\n\nAbstract: To solve the two-class classification problem existing in semantic-based image understanding, a novel classification method based on double manifold learning is proposed, which can transform the classification problem from a high-dimensional data space to a feature space with lower dimensionality. Two manifolds with different intrinsic dimensionalities will be first established separately, according to the significant differences between the positive samples and the negative ones, where globular neighborhood-based locally linear embedding (GNLLE) algorithm is adopted to implement dimensionality reduction and meantime unsupervised clustering. Then the aggregation center of each manifold is calculated, taking into account the grouping characteristics of similar samples. Furthermore, a new classifier is constructed for a double manifold learning model via distance companion. Finally experiments indicate that our method, which can be easily extended to multi-classification manifold learning, will not only reflect the topological structure of the whole data more precisely, but also achieve performance of classification more efficiently.","Title: XML based interactive video and data services over cable\nYear: 2000\n\nAbstract: The growing use of cable to broadcast digital TV programs provides the opportunity for delivering digital data services. Multi-dimensional information can be inserted into plain video streams. The information could be stock data, weather forecast or electronic programs guide. In our project, we embed the data which are related to the objects in video and provide more information about those objects. This is much like the hyperlinks in web pages. it's useful in such areas as advertising, distance education and entertainment This paper concisely describes the in-progress research of the process of data authoring and the use of XML to solve some problems within it.","Title: A novel intelligent strategy for improving measurement precision of FOG\nYear: 2000\n\nAbstract: This paper discusses a neural network-based strategy for reducing the existing errors of fiber-optic gyroscope (FOG). A series-single-layer neural network, which is composed of two single-layer networks in series, is presented for eliminating random noises. This network has simpler architecture, faster learning speed, and better performance compared to conventional backpropagation (BP) networks. A...","Title: A novel hybrid model for image classification\nYear: 2011\n\nAbstract: Recently, biological intelligent computing gains more and more attention in analysing large-scale real world datasets. Because the performance of the support vector machine (SVM) classifier is always degraded by poor feature subsets and inappropriate parameters for training, an improved quantum-behaved particle swarm optimisation (IQPSO) is introduced to optimise the features and parameters synchronically, aiming to improve the generalisation of the SVM classifier. That is, a novel hybrid image classification model by combing SVM and IQPSO, called as IQPSO_SVM is presented in this paper. Experimental results show that the proposed IQPSO_SVM improves the classification accuracy greatly compared to the traditional SVM with grid search, and outperforms such SVM based on genetic algorithm (GA_SVM) without accuracy loss.","Title: Linear grouping using orthogonal regression\nYear: 2006\n\nAbstract: A new method to detect different linear structures in a data set, called Linear Grouping Algorithm (LGA), is proposed. LGA is useful for investigating potential linear patterns in data sets, that is, subsets that follow different linear relationships. LGA combines ideas from principal components, clustering methods and resampling algorithms. It can detect several different linear relations at once. Methods to determine the number of groups in the data are proposed. Diagnostic tools to investigate the results obtained from LGA are introduced. It is shown how LGA can be extended to detect groups characterized by lower dimensional hyperplanes as well. Some applications illustrate the usefulness of LGA in practice.","Title: Semantic Image Retrieval Based on Multiple-Instance Learning\nYear: 2010\n\nAbstract: Image semantics have received more and more attention because of the huge gap between the low-level features and the semantics. Semantic image retrieval is a challenging problem and became a research focus. This paper presents a semantic image retrieval approach based on multiple-instance learning. In multiple-instance learning, the training samples are bags composed of instances without labels. The proposed approach realizes the mapping from low-level features to simple semantics and the mapping from simple semantics to compound semantics by means of multiple-instance learning. The obtained semantics are used in semantic image retrieval. The experiment results show that the proposed approach is able to process semantic image retrieval more reliably and more effectively.","Title: Parallel Matrix Multiplication Algorithm Based on Vector Linear Combination Using MapReduce\nYear: 2013\n\nAbstract: Matrix multiplication is used in a variety of applications. It requires a lot of computation time especially for large-scale matrices. Parallel processing is a good choice for matrix multiplication operation. To overcome the efficiencies of existing algorithms for parallel matrix multiplication, a matrix multiplication processing scheme based on vector linear combination (VLC) was presented. The VLC scheme splits the matrix multiplication procedure into two steps. The first step obtains the weighted vectors by scalar multiplication. The second step gets the final result through a linear combination of the weighted vectors with identical row numbers. We present parallel matrix multiplication implementations using MapReduce (MR) based on VLC scheme and explain in detail the MR job. The map method receives the matrix input and generates intermediate (key, value) pairs according to the VLC scheme requirement. The reduce method conducts the scalar multiplication and vectors summation. In the end, the reduce method outputs the result in the way of row vector. Then performance theoretical analysis and experiment result comparing with other algorithms are proposed. Algorithm presented in this paper needs less computation time than other algorithms. Finally, we conclude the paper and propose future works.","Title: A Novel Micro Air Vehicle with Flexible Wing Integrated with On-board Electronic Devices\nYear: 2008\n\nAbstract: This paper presents an electrically powered micro air vehicle (MAV) with a flexible wing integrated with on-board electronic components that is built at Tsinghua University. The low aspect ratio wing, adopting the airfoil of S5010 and Zimmerman shape, is made up of a flexible printed circuit membrane (FPCM) that covers a thin carbon fiber skeleton. The real MAV prototype is tested in a low-speed wind tunnel in order to evaluate its aerodynamic characteristics. The comparing experiments are conducted on the flexible wing and its rigid counterpart with the same size and the same wing shape to illustrate the aerodynamic advantages of the flexible wing. The results of the wind tunnel experiments indicate that the flexible wing has a larger angle of stall, bigger maximum lift coefficient than the rigid one. However, the lift-drag ratio of the flexible wing varies in a complex way because the flexible wing also increases the drag with the lift growth. The FPCM functions as both the skin of the aircraft wing and the supporting substrate for the electronic components, such as micro hot-film flow speed sensors that are used to determine 3 fundamental flight parameters: air speed, angle of attack and sideslip angle. In addition, most of the signal processing circuits is distributed on the FPCM, which remarkably reduces the autopilot load. The dimensions of a homemade autopilot that is separately installed in the fuselage are 35times20times12 mm with the weight of 6 g. Through experiments of real flights, the turning, climbing, maneuverability and wind resistant ability of the MAV are tested. The flight results show that the MAV can fly with good stability and maneuverability.","Title: Image Classification Approach Based on Manifold Learning in Web Image Mining\nYear: 2009\n\nAbstract: Automatic image classification is a challenging research topic in Web image mining. In this paper, we formulate image classification problem as the calculation of the distance measure between training manifold and test manifold. We propose an improved nonlinear dimensionality reduction algorithm based on neighborhood optimization, not only to decrease feature dimensionality but also to transform the problem from high-dimensional data space into low-dimensional feature space. Considering that the images in most real-world applications have large diversities within category and among categories, we propose a new scheme to construct a set of training manifolds each representing one semantic category and partition each nonlinear manifold into several linear sub-manifolds via region growing. Moreover, to further reduce computational complexity, each sub-manifold is depicted by aggregation center. Experimental results on two Web image sets demonstrate the feasibility and effectiveness of the proposed approach.","Title: Estimating the error variance after a pre-test for an interval restriction on the coefficients\nYear: 2011\n\nAbstract: This paper considers the estimation of the error variance after a pre-test of an interval restriction on the coefficients. We derive the exact finite sample risks of the interval restricted and pre-test estimators of the error variance, and examine the risk properties of the estimators to model misspecification through the omission of relevant regressors. It is found that the pre-test estimator performs better than the interval restricted estimator in terms of the risk properties in a large region of the parameter space; moreover, its risk performance is more robust with respect to the degrees of model misspecification. Furthermore, we propose a bootstrap procedure for estimating the risks of the estimators, to overcome the difficulty of computing the exact risks.","Title: Constructing a Novel Pos-neg Manifold for Global-Based Image Classification.\nYear: 2013\n\nAbstract: For the task of global-based image classification, we construct an image manifold, i.e., a pos-neg manifold, based on the solving strategies of two-class classification problem, which includes a positive sub-manifold and a negative one. We also present an improved globular neighborhood based locally linear embedding (an improved GNLLE) algorithm, fully taking account of the big differences between the positive and negative category images, thus the data distance calculation defined in the high-dimensional space can be translated into the one on the image manifold with lower dimensionality. Moreover, to simplify the distance measure between two nonlinear sub-manifolds, we put forward a clustering-based method to determine a manifold center for each sub-manifold. Experimental results on the real-world Web images show that the proposed method can improve the classification performance significantly. © Springer-Verlag 2013.","Title: New Approach for Embedded Computer Numeric Control Development\nYear: 2008\n\nAbstract: After analyzing the shortcomings of traditional code-centric development process for Embedded Computer Numeric Control (CNC), this paper presents a new approach: Embedded cNc Development based on modEl Driven (ENDED) which enjoys the advantages of model-driven development (MDD) and domain specific modeling (DSM). This approach is a model-based methodology which includes three parts: construction of domain modeling language, model transformation, code auto-generation from domain model. Multi-view based meta-modeling method was employed in the first step of ENDED to construct the CNC modeling language. During the model transformation part, three requirements of model transformation were proposed and corresponding processing strategies were elaborated. In the last part, code auto generator based on domain library to improve the productivity was described in details and an illustrative example was tested to show the feasibility of ENDED.","Title: A flexible flow sensor system and its characteristics for fluid mechanics measurements.\nYear: 2009\n\nAbstract: In this paper, we present a novel micromachined hot-film flow sensor system realized by a technique using a film depositing processes and incorporating a standard printed circuit. Sensor electrodes and electronic circuits are preprinted on a flexible substrate of polyimide (PI), i.e., a flexible printed circuit board (FPCB). The sensing element, which is made of Cr/Ni/Pt with a temperature coefficient of resistance around 2,000 ppm/K, is fabricated on the FPCB by either magnetron sputtering technology or pulsed laser deposition (PLD). The sensor can be packed efficiently at high-density and integrated with signal processing circuits without additional pads. A simple fabrication process using mature technique and materials selection guarantees that the time and costs are greatly reduced. Both steady-state and transient characteristics of the sensors are experimentally tested, and the results presented to validate the effectiveness of the sensors.","Title: Development of Micro Air Vehicle Based on Aerodynamic Modeling Analysis in Tunnel Tests\nYear: 2005\n\nAbstract: This paper presents development of an electrically powered Micro Air Vehicle (MAV) prototype based on aerodynamic analysis in wind tunnel and water tunnel tests. Two airframe models in triangle and square wing planforms, each with a wingspan of 100mm, are analyzed with a small-scale low speed wind tunnel to examine the practical characteristics at the low Reynolds number. The test in a water tunnel is further carried out to investigate the relationship between the vortex aerofoil design and turbulences created. The testing results show that the triangle wing aerofoil appears greater maximum lift coefficient and little occurrence of vortex and turbulences. Based on the verified wing planform in the tunnel tests, a MAV prototype was further designed and fabricated, with successful tests in the real flight.","Title: Collision-free Path Planning and Trajectory Generation for MAVs Flying in Urban Terrain\nYear: 2006\n\nAbstract: This paper presents an optimal algorithm for finding collision-free path and trajectory for microair vehicles (MAVs) in urban terrain where multiple ground obstacles are distributed. Regarding vertices of polygonal obstacles as input points of the Delaunay triangulations, a Delaunay-based path planning is proposed to determine an optimal waypoint path while considering criterions of minimum fuel expenditure and collision risk. A trajectory generation method with corresponding optimal constraints is further developed to yield feasible fly trajectory along the planned path. The off-line pre-planning and on-line updated planning are integrated to enhance autonomy of vehicles flying in dangerous situations, with tight maneuvering and operational capability. Simulation results of a mission scenario are finally presented to demonstrate effectiveness of the proposed approach","Title: Mining item-item and between-set correlated association rules.\nYear: 2011\n\nAbstract: To overcome the failure in eliminating suspicious patterns or association rules existing in traditional association rules\n mining, we propose a novel method to mine item-item and between-set correlated association rules. First, we present three\n measurements: the association, correlation, and item-set correlation measurements. In the association measurement, the all-confidence\n measure is used to filter suspicious cross-support patterns, while the all-item-confidence measure is applied in the correlation\n measurement to eliminate spurious association rules that contain negatively correlated items. Then, we define the item-set\n correlation measurement and show its corresponding properties. By using this measurement, spurious association rules in which\n the antecedent and consequent item-sets are negatively correlated can be eliminated. Finally, we propose item-item and between-set\n correlated association rules and two mining algorithms, I&ISCoMine_AP and I&ISCoMine_CT. Experimental results with synthetic\n and real retail datasets show that the proposed method is effective and valid.","Title: Smart Wheelchair Navigation Based on User's Gaze on Destination\nYear: 2010\n\nAbstract: Designing intelligent navigation systems is a challenging task because environmental uncertainty may prevent mission accomplishment. This paper presents a smart wheelchair navigation system using information from the goal position indicated by the user's gaze. The system tracks the user's head with a web camera to determine the direction where the gaze is fixed. Then, it detects the area that the user gazed at, in the panoramic image obtained from an omni-directional camera and sets the area as the destination. Once the destination is fixed, navigation starts by rotating the wheelchair heading to the destination by visual servoing with SURF descriptors around the destination area. During maneuver, a laser range sensor scans critical wheelchair's area for obstacles. If detected, their distribution is analyzed to generate steering commands for avoiding them and eventually ensuring the wheelchair's pose towards the goal. Experimental operation in indoor environments has shown the feasibility of the proposed system.","Title: A wireless portable system with microsensors for monitoring respiratory diseases.\nYear: 2012\n\nAbstract: A wireless portable monitoring system for respiratory diseases using microsensors is proposed. The monitoring system consists of two sensor nodes integrating with Bluetooth transmitters that measure user's respiratory airflow, blood oxygen saturation, and body posture. The utility of micro-hot-film flow sensor makes the monitor can acquire comprehensive respiration parameters which are useful for ...","Title: A two-level strategy for segmenting center of interest from pictures\nYear: 2011\n\nAbstract: Segmenting center of interests (COIs) from pictures is an important but highly challenging problem for researchers in computer vision and image processing. The capability of understanding the meanings of pictures by computers can lead to breakthroughs in a wide range of applications including Web image search and online picture-sharing communities. In this paper, a two-level strategy is presented, which consists of a rough segmentation stage and a fine segmentation stage. In the first level, a picture is partitioned into four regions by using a block clustering method based on color and texture features, and the COI within the picture is distinguished from the background according to the principles of photographic composition. This stage aims to determine the approximate region of the target. In the second level, a novel active contour model is established based on shape information and vector method, where the image energy is defined by a hue gradient and the external energy is generated from either a triangular inner force or a supplementary force. This stage tries to extract the boundary of the target accurately. Experimental results on photos downloaded from the Internet show the feasibility and effectiveness of the proposed method.","Title: Aircraft aerodynamic parameter detection using micro hot-film flow sensor array and BP neural network identification.\nYear: 2012\n\nAbstract: Air speed, angle of sideslip and angle of attack are fundamental aerodynamic parameters for controlling most aircraft. For small aircraft for which conventional detecting devices are too bulky and heavy to be utilized, a novel and practical methodology by which the aerodynamic parameters are inferred using a micro hot-film flow sensor array mounted on the surface of the wing is proposed. A back-propagation neural network is used to model the coupling relationship between readings of the sensor array and aerodynamic parameters. Two different sensor arrangements are tested in wind tunnel experiments and dependence of the system performance on the sensor arrangement is analyzed.","Title: Micro thermal flow sensors/systems on flexible PCB and extensive applications\nYear: 2013\n\nAbstract: We demonstrate our researches on developing micro thermal flow sensors by depositing nano metallic films on flexible substrates for detecting surface flow. The fabrication of the sensors is incorporating standard printed circuit technique with micromachining deposit/sputter, which takes advantages of low cost, easy fabrication, easy packaging and integrating sensors with processing circuits. The applications using the sensors to detect airflow around air vehicles, underwater wall shear stress, and to measure respiratory flow for monitoring and diagnosing respiratory diseases are also presented.","Title: Modeling and experimental study on characterization of micromachined thermal gas inertial sensors.\nYear: 2010\n\nAbstract: Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication.","Title: Research on the distribution of geomagnetic daily variation along some station chains in China\nYear: 2011\n\nAbstract: The temporal and spatial distribution of Sq(H)in China was analyzed based on the geomagnetic digitized data from the geomagnetic observation network.It was found that:(1)there was obvious prenoon-postnoon asymmetry of Sq(H)in Summer and Equinox.(2)in Summer,Equinox and Winter,the averaged focus position of Sq were 27 ° N,29 ° N and 35 ° N respectively.But in a single quiet day,the focus of Sq might appear in the north of 50 ° N and in the south of 19 ° N.(3)there were some special behavior of the Sq(H)distributions such as the latitudinal trend inconsistencies in two longitudinal chain,the reverse of Sq(H)variations in the same latitudinal chain and the increase(decrease)of the daily ranges from east to west.All these demonstrated that there might be latitudinal migration of the Sq focus or changes in current intensity during the longitudinal migration of Sq focus from east to west.","Title: Testing inequality constraints in a linear regression model with spherically symmetric disturbances.\nYear: 2014\n\nAbstract: This paper develops a Wald statistic for testing the validity of multivariate inequality constraints in linear regression models with spherically symmetric disturbances, and derive the distributions of the test statistic under null and nonnull hypotheses. The power of the test is then discussed. Numerical evaluations are also carried out to examine the power performances of the test for the case in which errors follow a multivariate student-t (Mt) distribution.","Title: Adaptive mode assignment in performance-critical cyber-physical systems\nYear: 2015\n\nAbstract: Distributed cyber-physical systems(CPS) deployed in performance-critical applications are imposed stringent constraints such as the real-time requirement and energy consumption budget. However, the performance of CPS is inevitably undermined by various physical uncertainties, which include stochastic environment noise and dynamics of the physical phenomenon. Both of those uncertainties might lead to overload and the power overconsumption as task execution times are unpredictable. While recent feedback control scheduling have shown promise to meet the end-to-end deadlines by adaptively adjusting the task loading rate, little work has focused on both the system service rate and the CPU execution modes as a whole to minimize the system power consumption. This paper presents a feedback control based algorithm that adaptively maintains desired task service rate for real-time requirement while minimizes the power consumption by assigning proper execution modes on processor for each node. The theoretic analysis and numerous simulations demonstrate that the proposed scheme can provide robust real-time guarantees and reduce the power consumption when the task workload vary significantly at run-time.","Title: The design of Ambisonic reproduction system based on dynamic gain parameters\nYear: 2014\n\nAbstract: This paper describes a design approach of Ambisonic reproduction system based on dynamic gain parameters (DGP). In the conventional approaches, the fixed gain parameters are often optimized to minimize the overall objective function for whole 360° sound stage. The proposed approach has an advantage that the gain parameters vary with angles of source objects. The problem of optimization tradeoff among different angles is overcome by DGP, which achieves an optimal solution in each position. Source localizations of the B-Format signals were estimated in frequency bands in order to match the corresponding gain parameters. For the synthesized signals, the process was simplified by the given spatial information. Using the head-related transfer function (HRTF) analysis, the proposed approach was found to be significantly better than reference approaches in interaural time difference (ITD) and interaural level difference (ILD).","Title: The design of HOA irregular decoders based on the optimal symmetrical virtual microphone response\nYear: 2014\n\nAbstract: Ambisonic decoder for irregular speaker arrays could be derived by optimization techniques. In terms of higher order reproduction system, the optimization program is hard to be guided to a large number of decoder coefficients. This paper describes a new method for higher order decoder based on the optimal symmetrical virtual microphone response (OSVMR). In the proposed method, the number of the decoder coefficients is reduced and the optimal symmetrical polar pattern of speaker feeds is obtained. The binaural evaluation demonstrates that the proposed method is found to be significantly better than reference methods on interaural time difference (ITD) and interaural level difference (ILD).","Title: Integration of micro sensors with mobile devices for monitoring vital signs of sleep apnea patients\nYear: 2014\n\nAbstract: Body Sensor Networks (BSNs) integrating micro sensor nodes with wireless communication are becoming flourishing in medical applications. This paper demonstrates a BSN-based portable monitor integrating micro sensors with mobile devices for monitoring and diagnosing obstructive sleep apnea syndrome (OSAS) at home. The system uses a micro hot-film flow sensor to detect respiratory flow, uses tri-axis micro accelerometer to detect body posture and motion intensity, and uses a micro photoelectric sensor to detect oxygen saturation of blood. The real-time vital signs are detected and transmitted wirelessly to a mobile device. The transmitted data are processed and analyzed in the mobile device and can be further transmitted to a remote medical center and physicians through mobile cellular networks or Internet for comprehensively analyzing, assessing, and diagnosing to the diseases.","Title: The design of ambisonics decoders for irregular speaker array conforming to subjective perception\nYear: 2014\n\nAbstract: An analysis of previously derived Ambisonics decoders shows that the mid-high frequency performance of these decoders has poor agreement with subjective perception, since the optimized decoder coefficients could not well meet the objectives developed by the energy vector, and the polar pattern of speaker feeds is suboptimal. In this paper, new objectives are added to fitness function for the optimal speaker response, and the sum of weighted rations genetic algorithm is applied to search a good set of decoder coefficients to meet all the objectives. The decoder of an example application of ITU-4.0 speaker array exhibits a significant improvement in localization performance at the rear of the listeners. In addition, the binaural evaluation demonstrates that the performance of the proposed decoder better conform to the subjective perception.","Title: A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.\nYear: 2016\n\nAbstract: Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 x 38 x 25 mm(3). The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 x 10(4) /cm(3) and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices.","Title: SimRank computation on uncertain graphs\nYear: 2016\n\nAbstract: SimRank is a similarity measure between vertices in a graph, which has become a fundamental technique in graph analytics. Recently, many algorithms have been proposed for efficient evaluation of SimRank similarities. However, the existing SimRank computation algorithms either overlook uncertainty in graph structures or is based on an unreasonable assumption (Du et al). In this paper, we study SimRank similarities on uncertain graphs based on the possible world model of uncertain graphs. Following the random-walk-based formulation of SimRank on deterministic graphs and the possible worlds model of uncertain graphs, we define random walks on uncertain graphs for the first time and show that our definition of random walks satisfies Markov's property. We formulate the SimRank measure based on random walks on uncertain graphs. We discover a critical difference between random walks on uncertain graphs and random walks on deterministic graphs, which makes all existing SimRank computation algorithms on deterministic graphs inapplicable to uncertain graphs. To efficiently compute SimRank similarities, we propose three algorithms, namely the baseline algorithm with high accuracy, the sampling algorithm with high efficiency, and the two-phase algorithm with comparable efficiency as the sampling algorithm and about an order of magnitude smaller relative error than the sampling algorithm. The extensive experiments and case studies verify the effectiveness of our SimRank measure and the efficiency of our SimRank computation algorithms.","Title: Gene Expression Programming With Multiple Chromosomes\nYear: 2011\n\nAbstract: Gene expression programming (GEP) has been widely used in the areas of pattern recognition and knowledge discovery, however, when dealing with complicated problems, it is very time-consuming and the number of generations is large. In order to overcome these drawbacks, this paper proposes a multi-chromosomes GEP algorithm (MC-GEP). Firstly, the individual is composed of multiple chromosomes, each chromosome consists of one or more genes. Secondly, the expression of each chromosome or combinations of several chromosomes may be chosen to indicate the individual. Finally, chromosome recombination is changed and performed orderly like meiosis. Experimental results show that MC-GEP can reduce the running time and the number of generations with respect to the GEP.","Title: Top-k Reliability Search on Uncertain Graphs\nYear: 2015\n\nAbstract: Uncertain graphs have been widely used to represent graph data with inherent uncertainty in structures. Reliability search is a fundamental problem in uncertain graph analytics. This paper studies a new problem, the top-k reliability search problem on uncertain graphs, that is, finding k vertices v with the highest reliabilities of connections from a source vertex s to v. Note that the existing algorithm for the threshold-based reliability search problem is inefficient for the top-k reliability search problem. We propose a new algorithm to efficiently solve the top-k reliability search problem. The algorithm adopts two important techniques, namely the BFS sharing technique and the offline sampling technique. The BFS sharing technique exploits overlaps among different sampled possible worlds of the input uncertain graph and performs a single BFS on all possible worlds simultaneously. The offline sampling technique samples possible worlds offline and stored them using a compact structure. The algorithm also takes advantages of bit vectors and bitwise operations to improve efficiency. Moreover, we generalize the top-k reliability search problem to the multi-source case and show that the multi-source case of the problem can be equivalently converted to the single-source case of the problem. Extensive experiments carried out on both real and synthetic datasets verify that the optimized algorithm outperforms the baselines by 1 -- 2 orders of magnitude in execution time while achieving comparable accuracy. Meanwhile, the optimized algorithm exhibits linear scalability with respect to the size of the input uncertain graph.","Title: System Error Compensation Methodology Based on a Neural Network for a Micromachined Inertial Measurement Unit.\nYear: 2016\n\nAbstract: Errors compensation of micromachined-inertial-measurement-units (MIMU) is essential in practical applications. This paper presents a new compensation method using a neural-network-based identification for MIMU, which capably solves the universal problems of cross-coupling, misalignment, eccentricity, and other deterministic errors existing in a three-dimensional integrated system. Using a neural network to model a complex multivariate and nonlinear coupling system, the errors could be readily compensated through a comprehensive calibration. In this paper, we also present a thermal-gas MIMU based on thermal expansion, which measures three-axis angular rates and three-axis accelerations using only three thermal-gas inertial sensors, each of which capably measures one-axis angular rate and one-axis acceleration simultaneously in one chip. The developed MIMU (100 x 100 x 100 mm(3)) possesses the advantages of simple structure, high shock resistance, and large measuring ranges (three-axes angular rates of +/- 4000 degrees/s and three-axes accelerations of +/- 10 g) compared with conventional MIMU, due to using gas medium instead of mechanical proof mass as the key moving and sensing elements. However, the gas MIMU suffers from cross-coupling effects, which corrupt the system accuracy. The proposed compensation method is, therefore, applied to compensate the system errors of the MIMU. Experiments validate the effectiveness of the compensation, and the measurement errors of three-axis angular rates and three-axis accelerations are reduced to less than 1% and 3% of uncompensated errors in the rotation range of +/- 600 degrees/s and the acceleration range of +/- 1 g, respectively.","Title: Self-Tuning Fully-Connected PID Neural Network System for Distributed Temperature Sensing and Control of Instrument with Multi-Modules.\nYear: 2016\n\nAbstract: High integration of multi-functional instruments raises a critical issue in temperature control that is challenging due to its spatial-temporal complexity. This paper presents a multi-input multi-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating the temperature environment within a multi-module instrument. The smart system ensures that the internal temperature of the instrument converges to a target without the need of a system model, thus making the control robust. The system consists of a fully-connected proportional-integral-derivative (PID) neural network (FCPIDNN) and an on-line self-tuning module. The experimental results show that the presented system can effectively control the internal temperature under various mission scenarios, in particular, it is able to self-reconfigure upon actuator failure. The system provides a new scheme for a complex and time-variant MIMO control system which can be widely applied for the distributed measurement and control of the environment in instruments, integration electronics, and house constructions.","Title: Towards efficient top-k reliability search on uncertain graphs.\nYear: 2017\n\nAbstract: Uncertain graph has been widely used to represent graph data with inherent uncertainty in structures. Reliability search is a fundamental problem in uncertain graph analytics. This paper investigates on a new problem with broad real-world applications, the top-k reliability search problem on uncertain graphs, that is, finding the k vertices v with the highest reliabilities of connections from a source vertex s to v. Note that the existing algorithm for the threshold-based reliability search problem is inefficient for the top-k reliability search problem. We propose a new algorithm to efficiently solve the top-k reliability search problem. The algorithm adopts two important techniques, namely the BFS sharing technique and the offline sampling technique. The BFS sharing technique exploits overlaps among different sampled possible worlds of the input uncertain graph and performs a single BFS on all possible worlds simultaneously. The offline sampling technique samples possible worlds offline and stores them using a compact structure. The algorithm also takes advantages of bit vectors and bitwise operations to improve efficiency. In addition, we generalize the top-k reliability search problem from single-source case to the multi-source case and show that the multi-source case of the problem can be equivalently converted to the single-source case of the problem. Moreover, we define two types of the reverse top-k reliability search problems with different semantics on uncertain graphs. We propose appropriate solutions for both of them. Extensive experiments carried out on both real and synthetic datasets verify that the optimized algorithm outperforms the baselines by 1---2 orders of magnitude in execution time while achieving comparable accuracy. Meanwhile, the optimized algorithm exhibits linear scalability with respect to the size of the input uncertain graph.","Title: Elimination of Drifts in Long-Duration Monitoring for Apnea-Hypopnea of Human Respiration.\nYear: 2016\n\nAbstract: This paper reports a methodology to eliminate an uncertain baseline drift in respiratory monitoring using a thermal airflow sensor exposed in a high humidity environment. Human respiratory airflow usually contains a large amount of moisture (relative humidity, RH >85%). Water vapors in breathing air condense gradually on the surface of the sensor so as to form a thin water film that leads to a significant sensor drift in long-duration respiratory monitoring. The water film is formed by a combination of condensation and evaporation, and therefore the behavior of the humidity drift is complicated. Fortunately, the exhale and inhale responses of the sensor exhibit distinguishing features that are different from the humidity drift. Using a wavelet analysis method, we removed the baseline drift of the sensor and successfully recovered the respiratory waveform. Finally, we extracted apnea-hypopnea events from the respiratory signals monitored in whole-night sleeps of patients and compared them with golden standard polysomnography (PSG) results.","Title: Highly Sensitive Hot-Wire Anemometry Based on Macro-Sized Double-Walled Carbon Nanotube Strands.\nYear: 2017\n\nAbstract: This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs) as sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT) strands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor is demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by suspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of silver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive TCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current was applied between the two prongs. This sensor can evidently respond to flow rate, and requires only several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor has better sensitivity than the Pt-coated DWCNT sensor.","Title: A Case Study of Land-Surface-Temperature Impact from Large-Scale Deployment of Wind Farms in China from Guazhou.\nYear: 2016\n\nAbstract: The wind industry in China has experienced a rapid expansion of capacity after 2009, especially in northwestern China, where the China's first 10 GW-level wind power project is located. Based on the analysis from Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data for period of 2005-2012, the potential LST impacts from the large-scale wind farms in northwestern China's Guazhou are investigated in this paper. It shows the noticeable nighttime warming trends on LST over the wind farm areas relative to the nearby non-wind-farm regions in Guazhou and that the nighttime LST warming is strongest in summer (0.51 degrees C/8 years), followed by autumn (0.48 degrees C/8 years) and weakest in winter (0.38 degrees C/8 years) with no warming trend observed in spring. Meanwhile, the quantitative comparison results firstly indicate that the nighttime LST warming from wind farm areas are less than those from the urban areas in this work.","Title: Micromachined Fluid Inertial Sensors.\nYear: 2017\n\nAbstract: Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri- axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern.","Title: A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles.\nYear: 2017\n\nAbstract: Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30-500 nm, number concentration in range of 5 x 10(2)-5 x 10(7) / cm(3). The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles.","Title: A vessel segmentation method for low contrast CT angiography image.\nYear: 2016\n\nAbstract: CT angiography image vessel segmentation technique plays a critical role in many practical applications such as diagnosis of diseases and surgical planning. Blood vessels after angiography are often defective in low contrast and high noise due to individual differences and limitations of imaging device. A set of segmentation methods has been proposed for such data feature, which firstly adopts combination of average filtering with high frequency emphasizes filtering enhancement algorithms to perform enhancement preprocessing on the original image, thereby enhancing the contrast ratio of blood vessels and surrounding area; secondly, it performs vessel extraction on the enhanced data using region growth algorithm to obtain the segmentation data of richer vessel branches. Experimental results prove that the segmentation approach proposed here can accurately perform vessel segmentation and effectively avoid incorrect segmentation with better robustness.","Title: Online Multi-threshold Learning with Imbalanced Data Stream.\nYear: 2017\n\nAbstract: This paper addresses the imbalanced data problem in an online fashion based on multi-threshold learning. The majority of existing works on processing large-scale imbalanced data stream assume a prior distribution of data based on a training dataset, while we consider a more challenging setting without any assumption of the prior, and propose an online multi-threshold learning (OMTL) method by simultaneously learning multiple classifiers with different threshold based on F-measure incremental updating. The proposed approach shows its potentials on recent benchmark datasets compared to previous cost-sensitive and threshold fine-tuning based online learning algorithms.","Title: A hybrid intra refresh and reference selection scheme for mobile video coding\nYear: 2017\n\nAbstract: Real-time video performance is difficult to guarantee under mobile communication environments characterized by loss-probability-varying transmission channel, heterogeneous networks, and various mobile devices of different access capabilities. In this paper, a novel attention-based network-aware robust video coding scheme mixing adaptive intra refresh with reference picture selection is proposed to improve the visual experience for mobile video. This method unifies human visual attention, state information of wireless channel and hybrid refresh tools to realize optimum bitrate allocation so that uneven robustness for attentive image regions against the packet loss can be readily accomplished. Further, a set of tools serving for evaluating the refresh regions, refresh modes and reference decision are developed, considering a balance among the coding efficiency, error resilience and user experience. Experiments on H.264 show that the proposed scheme provides a much better subjective feeling than traditional refresh methods when compressed video is delivered over wireless channels.","Title: A FPGA-Based, Granularity-Variable Neuromorphic Processor and Its Application in a MIMO Real-Time Control System.\nYear: 2017\n\nAbstract: Artificial Neural Networks (ANNs), including Deep Neural Networks (DNNs), have become the state-of-the-art methods in machine learning and achieved amazing success in speech recognition, visual object recognition, and many other domains. There are several hardware platforms for developing accelerated implementation of ANN models. Since Field Programmable Gate Array (FPGA) architectures are flexible and can provide high performance per watt of power consumption, they have drawn a number of applications from scientists. In this paper, we propose a FPGA-based, granularity-variable neuromorphic processor (FBGVNP). The traits of FBGVNP can be summarized as granularity variability, scalability, integrated computing, and addressing ability: first, the number of neurons is variable rather than constant in one core; second, the multi-core network scale can be extended in various forms; third, the neuron addressing and computing processes are executed simultaneously. These make the processor more flexible and better suited for different applications. Moreover, a neural network-based controller is mapped to FBGVNP and applied in a multi-input, multi-output, (MIMO) real-time, temperature-sensing and control system. Experiments validate the effectiveness of the neuromorphic processor. The FBGVNP provides a new scheme for building ANNs, which is flexible, highly energy-efficient, and can be applied in many areas.","Title: Diversified Coherent Core Search on Multi-Layer Graphs.\nYear: 2018\n\nAbstract: Mining dense subgraphs on multi-layer graphs is an interesting problem, which has witnessed lots of applications in practice. To overcome the limitations of the quasi-clique-based approach, we propose d-coherent core (d-CC), a new notion of dense subgraph on multi-layer graphs, which has several elegant properties. We formalize the diversified coherent core search (DCCS) problem, which finds kd-CCs that can cover the largest number of vertices. We propose a greedy algorithm with an approximation ratio of \n \n \n \n $$1 - 1/e$$\n \n \n \n and two search algorithms with an approximation ratio of 1/4. Furthermore, we propose some optimization techniques to further speed up the algorithms. The experiments verify that the search algorithms are faster than the greedy algorithm and produce comparably good results as the greedy algorithm in practice. As opposed to the quasi-clique-based approach, our DCCS algorithms can fast detect larger dense subgraphs that cover most of the quasi-clique-based results.","Title: SimRank on Uncertain Graphs.\nYear: 2017\n\nAbstract: SimRank is a similarity measure between vertices in a graph. Recently, many algorithms have been proposed to efficiently evaluate SimRank similarities. However, the existing algorithms either overlook uncertainty in graph structures or depends on an unreasonable assumption. In this paper, we study SimRank on uncertain graphs. Following the random-walk-based formulation of SimRank on deterministic ...","Title: Predicting the quality of online health expert question-answering services with temporal features in a deep learning framework.\nYear: 2018\n\nAbstract: Currently, online health expert question-answering (HQA) services are the most popular services for health consumers to search online health information due to their convenience and the cost-effectiveness. However, one main challenge of these services is that the quality of the answers posted by physicians varies over a large spectrum. Physicians may not have sufficient time to answer the questions or just want to post advertisements in the answers. To determine high-quality answers, we can apply classification models on them. However, it is critical to include the corresponding features in the classification models. To further enhance the model performance, we propose a set of novel temporal features based on the characteristics of HQA services. Moreover, we propose a deep learning framework, referred to as a collaborative decision convolutional neural network (CDCNN), to learn the semantic non-linear features embedded in the data. By exploiting the learned non-linear semantic features, we can apply the factorization machines (FM) to obtain the quality score of an answer. Finally, we conduct extensive experiments to show the advantages of the proposed framework. (c) 2017 Elsevier B.V. All rights reserved.","Title: Sharpness-preservation video upscaling\nYear: 2017\n\nAbstract: Video upscaling is a common task performing the adaption of the actual video resolution to the screen display area. The extensively used interpolation methods are easily implemented but usually result in some artifacts, such as blurring and aliasing effects. This paper proposes to combine sharpening with interpolation to reduce the blurring effects of enlarged videos, in which videos are firstly preprocessed with sharpening to enhance profiles so as to compensate the loss of high-frequency components during interpolation. To tune sharpness degree in sharpening procedure, the blurriness metric considering image gradients as well as pixel intensities is particularly suggested and the generation rule for sharpening strength is accordingly regulated. In practice, three representative interpolation methods, namely, Bilinear, Bicubic and Lanczos, are experimentally incorporated into our framework to carry out validation. Results with respect to both original and decoded videos show the significant objective and subjective improvements against the respective regular interpolation.","Title: Cognitive Gravity Model Based Semi-Supervised Dimension Reduction.\nYear: 2018\n\nAbstract: Dimension reduction is very important for pattern recognition. Preserving the manifold is a popular way to enhance the effect of the dimension reduction method. However, most of the manifold is designed according to the distribution of the data but not the requirement of the classifier, and then the preserved manifold structure could be not what the classifier need. In this paper, we note that the samples are often with different densities, and it is often ignored by many classifiers, such as support vector machine and -nearest neighbors. To overcome this problem, a new manifold based on the cognitive gravity model and Laplace matrix is designed, where the weight of the similar matrix of the Laplace matrix is set by the corresponding gravity. As a result, the difference among the densities of samples can be reduced by preserving the manifold. Subsequently, a new semi-supervised dimension reduction based on the above manifold is designed. The conducted experiments validate the proposed approach in term of the performance of classification.","Title: Sparse Stochastic Online AUC Optimization for Imbalanced Streaming Data.\nYear: 2017\n\nAbstract: Area Under the ROC Curve (AUC) is an objective indicator of evaluating classification performance for imbalanced data. In order to deal with large-scale imbalanced streaming data, especially high-dimensional sparse data, this paper proposes a Sparse Stochastic Online AUC Optimization (SSOAO) method. Specifically, we first turn the standard online AUC optimization problem into a stochastic saddle point problem, then optimizing AUC by solving stochastic saddle point problem through AdaGrad optimizer. A sparse regularization term is also added for learning sparse data with high dimension. Comprehensive evaluation has been carried out on the recent benchmark. The experimental results show that the proposed SSOAO has the comparable performance on low-dimensional data, and outperforms other popular AUC optimization methods on high-dimensional sparse imbalanced streaming data. Both time and space complexity for model updating are reduced from O(d(2)) to O(d), which equal to the data dimension.","Title: Subsampled Optimization: Statistical Guarantees, Mean Squared Error Approximation, and Sampling Method.\nYear: 2018\n\nAbstract: For optimization on large-scale data, exactly calculating its solution may be computationally difficulty because of the large size of the data. In this paper we consider subsampled optimization for fast approximating the exact solution. In this approach, one gets a surrogate dataset by sampling from the full data, and then obtains an approximate solution by solving the subsampled optimization based on the surrogate. One main theoretical contributions are to provide the asymptotic properties of the approximate solution with respect to the exact solution as statistical guarantees, and to rigorously derive an accurate approximation of the mean squared error (MSE) and an approximately unbiased MSE estimator. These results help us better diagnose the subsampled optimization in the context that a confidence region on the exact solution is provided using the approximate solution. The other consequence of our results is to propose an optimal sampling method, Hessian-based sampling, whose probabilities are proportional to the norms of Newton directions. Numerical experiments with least-squares and logistic regression show promising performance, in line with our results.","Title: QuickIM: Efficient, Accurate and Robust Influence Maximization Algorithm on Billion-Scale Networks.\nYear: 2018\n\nAbstract: The Influence Maximization (IM) problem aims at finding k seed vertices in a network, starting from which influence can be spread in the network to the maximum extent. In this paper, we propose QuickIM, the first versatile IM algorithm that attains all the desirable properties of a practically applicable IM algorithm at the same time, namely high time efficiency, good result quality, low memory footprint, and high robustness. On real-world social networks, QuickIM achieves the $Omega(n + m)$ lower bound on time complexity and $Omega(n)$ space complexity, where $n$ and $m$ are the number of vertices and edges in the network, respectively. Our experimental evaluation verifies the superiority of QuickIM. Firstly, QuickIM runs 1-3 orders of magnitude faster than the state-of-the-art IM algorithms. Secondly, except EasyIM, QuickIM requires 1-2 orders of magnitude less memory than the state-of-the-art algorithms. Thirdly, QuickIM always produces as good quality results as the state-of-the-art algorithms. Lastly, the time and the memory performance of QuickIM is independent of influence probabilities. On the largest network used in the experiments that contains more than 3.6 billion edges, QuickIM is able to find hundreds of influential seeds in less than 4 minutes, while all the state-of-the-art algorithms fail to terminate in an hour.","Title: Towards Real-Time Service from Remote Sensing: Compression of Earth Observatory Video Data via Long-Term Background Referencing.\nYear: 2018\n\nAbstract: City surveillance enables many innovative applications of smart cities. However, the real-time utilization of remotely sensed surveillance data via unmanned aerial vehicles (UAVs) or video satellites is hindered by the considerable gap between the high data collection rate and the limited transmission bandwidth. High efficiency compression of the data is in high demand. Long-term background redundancy (LBR) (in contrast to local spatial/temporal redundancies in a single video clip) is a new form of redundancy common in Earth observatory video data (EOVD). LBR is induced by the repetition of static landscapes across multiple video clips and becomes significant as the number of video clips shot of the same area increases. Eliminating LBR improves EOVD coding efficiency considerably. First, this study proposes eliminating LBR by creating a long-term background referencing library (LBRL) containing high-definition geographically registered images of an entire area. Then, it analyzes the factors affecting the variations in the image representations of the background. Next, it proposes a method of generating references for encoding current video and develops the encoding and decoding framework for EOVD compression. Experimental results show that encoding UAV video clips with the proposed method saved an average of more than 54% bits using references generated under the same conditions. Bitrate savings reached 25-35% when applied to satellite video data with arbitrarily collected reference images. Applying the proposed coding method to EOVD will facilitate remote surveillance, which can foster the development of online smart city applications.","Title: An Asian Face Dataset and How Race Influences Face Recognition.\nYear: 2018\n\nAbstract: The face recognition scheme based on deep learning can give the best face recognition performance at present, but this scheme requires a large amount of labeled face data. The currently available large-scale face datasets are mainly Westerners, only containing few Asians. In practice, we have found that models trained using these data sets are lower in accuracy in identifying Asians than Westerners. Therefore, the establishment of a large-scale Asian face dataset is of great value for the development and deployment of face related applications for Asians. In this paper, we propose a simple semi-automatic approach to collect face images from Internet and build a large-scale Asian face dataset (AFD) containing 2019 subjects and 360,000 images. To the best of our knowledge, this is the largest Asian face image dataset proposed so far. To illustrate the quality of AFD, we train 3 different models with the same CNN structure yet by different training datasets (AFD, WebFace, mixed WebFace& AFD) and verify them on one Western and two Asian face testing datasets. Extensive experimental results show that the model by our AFD outperforms counterparts by a large margin for Asian face recognition. We have made the AFD dataset public to facilitate face recognition development for Asians.","Title: Dataset Refinement for Convolutional Neural Networks via Active Learning.\nYear: 2018\n\nAbstract: Convolutional neural networks (CNNs) have shown significant advantages in computer vision fields. For the optimizations of CNNs, most research works focus on feature extraction, which creates deeper structures and better activations, but the optimizations on dataset is rarely discussed. Due to the boom of data, most CNNs suffer from serious problems of dataset redundancy and following high computational burden. To this end, this paper brings in an informativeness ranking thought and proposes a new methodology for dataset refinement based on Active Learning. Extensive experiments prove its effectiveness to achieve a higher classification accuracy for CNNs at a less training cost. Moreover, for classification problems with a large number of class, this paper further proposes Entropy Ranking, a new Active Learning method, to enhance the optimization ability.","Title: A Fast Quantum Clustering Approach For Cancer Gene Clustering\nYear: 2018\n\nAbstract: At present, the main problem of gene expression data processing is how to use effective analytical methods to analyze gene expression data to obtain useful information. A large amount of useful information can be obtained by cluster analysis of gene expression data, which provides a basis for biology to predict cell cycle, predict the gene function, discover disease-causing genes and explain some new disease types. In this paper, a fast clustering method is proposed, which effectively combines the advantages of the graph regularized non-negative matrices factorization (GNMF) method with Quantum Clustering (QC) method, effectively improving the running speed of existing clustering methods and improving the clustering accuracy to some extent.","Title: Sparse Orthogonal Nonnegative Matrix Factorization For Identifying Differentially Expressed Genes And Clustering Tumor Samples\nYear: 2018\n\nAbstract: Gene expression data are critical for disease diagnoses and classification. However gene expression data usually are high-dimensional and high-noisy. Currently, many matrix factorization methods have been widely used for dimensionality reduction and data preprocessing in bioinformatics. Particularly, nonnegative matrix factorization (NMF) has the outstanding interpretability in analyzing gene expression data due to the nonnegative constraints. In this paper, a new nonnegative matrix factorization algorithm named sparse orthogonal nonnegative matrix factorization (SONMF) is proposed and applied to identify differentially expressed genes and cluster tumor samples, in which the L1-norm regularization and the orthogonal constraint are incorporated into the traditional NMF model to get more powerful data analysis tool. An iterative algorithm is proposed to optimize the new objective function. In order to prove the efficiency of the algorithm, SONMF is tested on four public gene expression datasets and compared with the other four NMF methods. The experimental results on the four real tumor datasets confirm the efficiency of SONMF for identifying differentially expressed genes and clustering tumor samples.","Title: A comparative performance analysis of evolutionary algorithms on $${\\varvec{k}}$$ k -median and facility location problems.\nYear: 2018\n\nAbstract: k-median and facility location problems are classical NP-hard combinatorial optimization problems. Although there are many experimental studies on them, their theoretical results are relatively few. This paper mainly contributes to investigating the approximation performance of two evolutionary algorithms for the k-median and facility location problems from a theoretical perspective. For k-median problem, we show that the evolutionary algorithms with standard bit mutation (SBM) operator can obtain approximation ratios 5 and \\(3{+}2/p\\) in expected polynomial time while the evolutionary algorithm with somatic contiguous hypermutation (CHM) operator cannot obtain them. For facility location problem, we show that the evolutionary algorithms with SBM operator can obtain approximation ratio 3 in expected polynomial time while the evolutionary algorithm with CHM operator cannot obtain it. Further, we prove that on a facility location instance the evolutionary algorithm with CHM operator greatly outperforms the evolutionary algorithm with SBM operator.","Title: A Wearable Multifunctional Pulse Monitor using Thermosensation-based Flexible Sensors.\nYear: 2019\n\nAbstract: The monitor is small, simple-structured, with multifunction, and thus provides a promising auxiliary approach for traditional Chinese medicine (TCM) pulse diagnosis.","Title: Integrative graph regularized matrix factorization for drug-pathway associations analysis.\nYear: 2019\n\nAbstract: We propose a novel drug-pathway association identification method: Integrative Graph regularized Matrix Factorization (IGMF). It employs graph regularization to encode data geometrical information and prevent possible overfitting in prediction. Furthermore, it achieves parts-based and sparse data representation by imposing L1-norm regularization on the objective function. Empirical studies demonstrate that IGMF has strong advantages in identifying more new drug-pathway associations compared to its peer methods. It further shows a good capability to unveil the intrinsic structures of data. As an effective drug-pathway discovery method, it will inspire new analytics methods in this subfield.","Title: A Proportional Odds Model Of Human Mobility And Migration Patterns\nYear: 2019\n\nAbstract: The modelling of human mobility and migration patterns has received much attention due to its substantial importance. Despite long-term efforts, we still lack a modelling framework that captures mobility patterns and further obtains a prospective view of movement trends with regards to diverse impacting factors. Here, we propose a proportional odds model of human mobility and migration (POM-HM) that takes a probabilistic approach to model human movements. Our model is based on the migration probability with a log-logistic distribution under the proportional odds assumption. Explanatory variables are introduced into the model by re-parameterizing the probability distribution function. The two resultant functions, namely, the migration strength and cumulative hazard, are used to estimate regional differences among travel fluxes and their tendencies. The performance of the POM-HM in terms of its validity and accuracy is examined and compared with the gravity model and the radiation model. The probability-based modelling framework enables us to investigate regional variations in migrant fluxes consequently further predict potential future patterns. In short, our modelling approach captures the probabilistic nature of human mobility and migration and furthers our understanding of both the spatiotemporal patterns of population movements and the impacts of various driving forces.","Title: Fast Rectangle Counting on Massive Networks\nYear: 2018\n\nAbstract: Rectangle has been recognized as an essential motif in a large number of real-world networks. Counting rectangles in a network plays an important role in network analysis. This paper comprehensively studies the rectangle counting problem on large networks. We propose a novel counting paradigm called the wedge-centric counting, where a wedge is a simple path consisting of three vertices. Unlike the traditional edge-centric counting, the wedge-centric counting uses wedges instead of edges as building blocks of rectangles. The main advantage of the wedge-centric counting is that it does not need to access two-hop neighbors. Based on this paradigm, we develop a collection of rectangle counting algorithms, including an in-memory algorithm with lower time complexity, an external-memory algorithm with the optimal I/O complexity, and two randomized algorithms with provable error bounds. The experimental results on a variety of real networks verify the effectiveness and the efficiency of the proposed wedge-centric rectangle counting algorithms.","Title: Dimensionality Reduction Via Adjusting Data Distribution Density\nYear: 2018\n\nAbstract: Dimensionality reduction is an important processing step for pattern recognition. Designing a new optimization goal is a popular method to improve the effect of the dimensionality decrease method. In this paper, we noted that the distribution density of data was not considered in the most classifiers, which may have a negative impact on the classifier. To overcome the above problem, a new optimization goal is designed under the distribution density of the data. In this optimization goal, the sample with smaller density owns larger impact for the optimization result, and then the density of sample could be adjusted to nearly the same in the low dimensional space. The experiments performed verified the proposed method in terms of classification performance.","Title: Image Artistic Style Migration Based On Convolutional Neural Network\nYear: 2018\n\nAbstract: In recent years, the wave of artificial intelligence technology, which is guided by deep learning, is becoming more and more widely applied to all fields of society. Among them, the cross collision between artificial intelligence and art has attracted great attention in related research fields. The migration of image artistic style based on deep learning has become one of the active research topics. In this paper, a simple and effective method is presented for image artistic style migration. That is, firstly, we specify an input image as an original image (it is also called a content image); at the same time, another or more images are designated as the desired image style. And then, by constructing the network model based on convolutional neural network (CNN), the image style can be transformed while the content information of the content image is guaranteed, so that the final output image shows the perfect combination of the content of the input image and the style of the style image. The core of the proposed artistic style migration strategy is the construction of an unified CNN framework. Here, a generation network is set up based on a deep residual network and the VGG-19 network model is applied to built a loss network. The experimental results on an application system show that our proposed method achieves a good synthesis effect for image artistic style migration.","Title: Air Quality Index Forecasting Based On Svm And Moments\nYear: 2018\n\nAbstract: A novel air quality index (AQI) forecasting method based on support vector machine (SVM) and moments is proposed in this paper. By using it, the AQI value of a sky image can be forecasted. In order to improve the forecasting accuracy and stability, color moments, color correlogram and wavelet features are used to extract the image features, which transfers the input image from color space to feature space. We train the SVM with the input of these extracted features. Then the trained SVM is utilized to achieve the AQI forecasting for new images. The experimental results improve that the proposed method has good AQI forecasting results, and the accuracy of the testing dataset is more than 82.3%, with 1300 training images and 200 test images.","Title: Truss decomposition of uncertain graphs.\nYear: 2017\n\nAbstract: The k-truss of a graph is the largest edge-induced subgraph such that every edge is contained in at least k triangles within the subgraph, where a triangle is a cycle consisting of three vertices. As a new notion of cohesive subgraphs, truss has recently attracted a lot of research attentions in the database and data mining fields. At the same time, uncertainty is an intrinsic property of massive graph data, and truss decomposition (i.e., finding all k-trusses of a graph) has become a key primitive on uncertain graphs. In this paper, we study the truss decomposition problem on uncertain graphs, that is, finding all highly probable k-trusses of an uncertain graph. We first give an formal statement of the truss decomposition problem on uncertain graphs. Then, we prove that the truss decomposition of an uncertain graph attains two elegant properties, namely uniqueness and hierarchy. We show that the truss decomposition of an uncertain graph can be found in $$O(m^{1.5}Q)$$O(m1.5Q) time by proposing an in-memory algorithm called $$\\\\mathtt {TD_{mem}}$$TDmem, where m is the number of edges of the uncertain graph, and Q is at most the maximum number of common neighbors of the endpoints of an edge. When an uncertain graph is too large to fit into main memory, we propose an external-memory algorithm $$\\\\mathtt {TD_{I/O}}$$TDI/O to find the truss decomposition of the uncertain graph. Extensive experiments have been carried out to evaluate the practical performance of the proposed algorithms. The experimental results verify that both $$\\\\mathtt {TD_{mem}}$$TDmem and $$\\\\mathtt {TD_{I/O}}$$TDI/O are efficient when an uncertain graph is small enough to fit into main memory, and that $$\\\\mathtt {TD_{I/O}}$$TDI/O is much faster than $$\\\\mathtt {TD_{mem}}$$TDmem when the graph is too large to fit into main memory.","Title: Quarter-Century Offshore Winds from SSM/I and WRF in the North Sea and South China Sea.\nYear: 2016\n\nAbstract: We study the wind climate and its long-term variability in the North Sea and South China Sea, areas relevant for offshore wind energy development, using satellite-based wind data, because very few reliable long-term in-situ sea surface wind observations are available. The Special Sensor Microwave Imager (SSM/I) ocean winds extrapolated from 10 m to 100 m using the Charnock relationship and the logarithmic profile method are compared to Weather Research and Forecasting (WRF) model results in both seas and to in-situ observations in the North Sea. The mean wind speed from SSM/I and WRF differ only by 0.1 m/s at Fino1 in the North Sea, while west of Hainan in the South China Sea the difference is 1.0 m/s. Linear regression between SSM/I and WRF winds at 100 m show correlation coefficients squared of 0.75 and 0.67, standard deviation of 1.67 m/s and 1.41 m/s, and mean difference of -0.12 m/s and 0.83 m/s for Fino1 and Hainan, respectively. The WRF-derived winds overestimate the values in the South China Sea. The inter-annual wind speed variability is estimated as 4.6% and 4.4% based on SSM/I at Fino1 and Hainan, respectively. We find significant changes in the seasonal wind pattern at Fino1 with springtime winds arriving one month earlier from 1988 to 2013 and higher winds in June; no yearly trend in wind speed is observed in the two seas.","Title: Research on concurrency comparison modeling based on $$\\uppi $$ calculus in future computer technology\nYear: 2019\n\nAbstract: \\(\\uppi \\) calculus is an effective tool targeted at the description and modeling of mobile concurrency systems. In this paper, a brief introduction of \\(\\uppi \\) calculus is followed with the discussion on the \\(\\uppi \\)-calculus-based description and modeling of the comparison operation, one of the basic computer operations. According to the two different ways of data storage: the indexed storage and linked-list storage of elements, the paper analyzes the \\(\\uppi \\)-calculus-based formalized description method in the comparison of any two elements. Moreover, a theoretical efficiency analysis is performed on the comparison algorithm of relatively complex linked-list storage of elements in this paper.","Title: Factorization machines and deep views-based co-training for improving answer quality prediction in online health expert question-answering services.\nYear: 2018\n\nAbstract: •Automatically exploit unlabeled answers to improve the learning performance without the need for expensive expert annotation.•Present a solution to train a good deep co-training framework on sparse short texts.•Introduce two unique deep textual views based on domain-specific word embeddings.•Propose a deep co-training framework to learn the hidden semantic embedding.","Title: AliGraph: A Comprehensive Graph Neural Network Platform.\nYear: 2019\n\nAbstract: An increasing number of machine learning tasks require dealing with large graph datasets, which capture rich and complex relationship among potentially billions of elements. Graph Neural Network (GNN) becomes an effective way to address the graph learning problem by converting the graph data into a low dimensional space while keeping both the structural and property information to the maximum extent and constructing a neural network for training and referencing. However, it is challenging to provide an efficient graph storage and computation capabilities to facilitate GNN training and enable development of new GNN algorithms. In this paper, we present a comprehensive graph neural network system, namely AliGraph, which consists of distributed graph storage, optimized sampling operators and runtime to efficiently support not only existing popular GNNs but also a series of in-house developed ones for different scenarios. The system is currently deployed at Alibaba to support a variety of business scenarios, including product recommendation and personalized search at Alibabau0027s E-Commerce platform. By conducting extensive experiments on a real-world dataset with 492.90 million vertices, 6.82 billion edges and rich attributes, AliGraph performs an order of magnitude faster in terms of graph building (5 minutes vs hours reported from the state-of-the-art PowerGraph platform). At training, AliGraph runs 40%-50% faster with the novel caching strategy and demonstrates around 12 times speed up with the improved runtime. In addition, our in-house developed GNN models all showcase their statistically significant superiorities in terms of both effectiveness and efficiency (e.g., 4.12%-17.19% lift by F1 scores).","Title: A Wearable Human Motion Tracking Device Using Micro Flow Sensor Incorporating with Micro Accelerometer.\nYear: 2020\n\nAbstract: Objective: This paper proposes a wearable human motion tracking device using micro flow sensor incorporating a micro accelerometer, which allows detecting postures of human limbs in dynamic motions. Methods: A micro flow sensor is used to detect motion velocity, from which, motion acceleration can be estimated. Thereby, the limb postures are figured out by using the components of the gravity accel...","Title: Motion Velocity, Acceleration and Energy Expenditure Estimation Using Micro Flow Sensor.\nYear: 2019\n\nAbstract: Motion velocity, acceleration, and energy expenditure estimations are important in quantitative assessments for physical recovery and exercise-based interventions for post-stroke patients with partial losses of neurological functions. This paper proposes a novel wearable motion estimation device using a micro flow sensor, which realizes motion velocity, acceleration detection, and energy expenditure estimation for human limb motion. A homemade micro thermal flow sensor is used to detect motion velocity. Jerk-Kalman based algorithm is proposed to extract motion acceleration from the flow sensor outputs. Motion velocity and acceleration are used to estimate energy expenditure of limb motion. Calibration experiments and application cases are conducted to validate the effectiveness of the methodology. The micro flow sensor based motion estimation method is free of accumulated error, robust for dynamic motion measurement, and provides a promising auxiliary approach for evaluating energy expenditures of human limbs in rehabilitation training.","Title: Constrained Truth Discovery\nYear: 2022\n\nAbstract: To aggregate useful information among diversified sources, a hotspot research topic called truth discovery has emerged in recent years. Existing truth discovery methods attempt to infer the true attribute values for the entities by identifying and trusting reliable data sources. That is, the values provided by reliable sources are more likely to be the true values. However, all these methods negle...","Title: Random Effect Bandits\nYear: 2022\n\nAbstract: This paper studies regret minimization in a multi-armed bandit. It is well known that side information, such as the prior distribution of arm means in Thompson sampling, can improve the statistical efficiency of the bandit algorithm. While the prior is a blessing when correctly specified, it is a curse when misspecified. To address this issue, we introduce the assumption of a random-effect model to bandits. In this model, the mean arm rewards are drawn independently from an unknown distribution, which we estimate. We derive a random-effect estimator of the arm means, analyze its uncertainty, and design a UCB algorithm ReUCB that uses it. We analyze ReUCB and derive an upper bound on its n-round Bayes regret, which improves upon not using the random-effect structure. Our experiments show that ReUCB can outperform Thompson sampling, without knowing the prior distribution of arm means.","Title: GraphScope: a unified engine for big graph processing\nYear: 2021\n\nAbstract: AbstractGraphScope is a system and a set of language extensions that enable a new programming interface for large-scale distributed graph computing. It generalizes previous graph processing frameworks (e.g., Pregel, GraphX) and distributed graph databases (e.g., Janus-Graph, Neptune) in two important ways: by exposing a unified programming interface to a wide variety of graph computations such as graph traversal, pattern matching, iterative algorithms and graph neural networks within a high-level programming language; and by supporting the seamless integration of a highly optimized graph engine in a general purpose data-parallel computing system.A GraphScope program is a sequential program composed of declarative data-parallel operators, and can be written using standard Python development tools. The system automatically handles the parallelization and distributed execution of programs on a cluster of machines. It outperforms current state-of-the-art systems by enabling a separate optimization (or family of optimizations) for each graph operation in one carefully designed coherent framework. We describe the design and implementation of GraphScope and evaluate system performance using several real-world applications.","Title: Cardinality Estimation in DBMS: A Comprehensive Benchmark Evaluation.\nYear: 2022\n\nAbstract: Cardinality estimation (CardEst) plays a significant role in generating high-quality query plans for a query optimizer in DBMS. In the last decade, an increasing number of advanced CardEst methods (especially ML-based) have been proposed with outstanding estimation accuracy and inference latency. However, there exists no study that systematically evaluates the quality of these methods and answer the fundamental problem: to what extent can these methods improve the performance of query optimizer in real-world settings, which is the ultimate goal of a CardEst method. In this paper, we comprehensively and systematically compare the effectiveness of CardEst methods in a real DBMS. We establish a new benchmark for CardEst, which contains a new complex realworld dataset STATS and a diverse query workload STATS-CEB. We integrate multiple most representative CardEst methods into an open-source database system PostgreSQL, and comprehensively evaluate their true effectiveness in improving query plan quality, and other important aspects affecting their applicability, ranging from inference latency, model size, and training time, to update efficiency and accuracy. We obtain a number of key findings for the CardEst methods, under different data and query settings. Furthermore, we find that the widely used estimation accuracy metric(Q-Error) cannot distinguish the importance of different sub-plan queries during query optimization and thus cannot truly reflect the query plan quality generated by CardEst methods. Therefore, we propose a new metric P-Error to evaluate the performance of CardEst methods, which overcomes the limitation of Q-Error and is able to reflect the overall end-to-end performance of CardEst methods. We have made all of the benchmark data and evaluation code publicly available at https://github.com/Nathaniel-Han/Endto-End-CardEst-Benchmark.","Title: Deep Bandits Show-Off: Simple and Efficient Exploration with Deep Networks.\nYear: 2021\n\nAbstract: Designing efficient exploration is central to Reinforcement Learning due to the fundamental problem posed by the exploration-exploitation dilemma. Bayesian exploration strategies like Thompson Sampling resolve this trade-off in a principled way by modeling and updating the distribution of the parameters of the action-value function, the outcome model of the environment.However, this technique becomes infeasible for complex environments due to the computational intractability of maintaining probability distributions over parameters of outcome models of corresponding complexity.Moreover, the approximation techniques introduced to mitigate this issue typically result in poor exploration-exploitation trade-offs, as observed in the case of deep neural network models with approximate posterior methods that have been shown to underperform in the deep bandit scenario.In this paper we introduce Sample Average Uncertainty (SAU), a simple and efficient uncertainty measure for contextual bandits.While Bayesian approaches like Thompson Sampling estimate outcomes uncertainty indirectly by first quantifying the variability over the parameters of the outcome model, SAU is a frequentist approach that directly estimates the uncertainty of the outcomes based on the value predictions.Importantly, we show theoretically that the uncertainty measure estimated by SAU asymptotically matches the uncertainty provided by Thompson Sampling, as well as its regret bounds.Because of its simplicity SAU can be seamlessly applied to deep contextual bandits as a very scalable drop-in replacement for epsilon-greedy exploration.We confirm empirically our theory by showing that SAU-based exploration outperforms current state-of-the-art deep Bayesian bandit methods on several real-world datasets at modest computation cost, and make the code to reproduce our results available at \\url{https://github.com/ibm/sau-explore}.","Title: Predicting miRNA-disease associations via layer attention graph convolutional network model\nYear: 2022\n\nAbstract: MiRNA is a class of non-coding single-stranded RNA molecules with a length of approximately 22 nucleotides encoded by endogenous genes, which can regulate the expression of other genes. Therefore, it is very important to predict the associations between miRNA and disease. Predecessors developed a new prediction method of drug-disease association, and it achieved good results. In this paper, we introduced the method of LAGCN to identify potential miRNA-disease associations. First, we integrate three associations into a heterogeneous network, such as the known miRNA-disease association, miRNA-miRNA similarities and disease-disease similarities, next we apply graph convolution network to learn the embedding of miRNA and disease. We use an attention mechanism to combine embedding from multiple convolution layers. Unobserved miRNA-disease associations are scored based on integrated embedding. After fivefold cross-validations, the value of AUC is reached 0.9091, which is higher than other prediction methods and baseline methods. In this paper, we introduced the method of LAGCN to identify potential miRNA-disease associations. LAGCN has achieved good performance in predicting miRNA-disease associations, and it is superior to other association prediction methods and baseline methods.","Title: Towards Energy-Efficient CGRAs via Stochastic Computing\nYear: 2022\n\nAbstract: Stochastic computing (SC) is a promising computing paradigm for low-power and low-cost applications with the added benefit of high error tolerance. Meanwhile, Coarse-Grained Re-configurable Architecture (CGRA) is also a promising platform for domain-specific applications for its combination of energy efficiency and flexibility. Intuitively, introducing SC to CGRA would synergistically reinforce the strengths of both paradigms. Accordingly, this paper proposes an SC-based CGRA by replacing the exact multiplication in traditional CGRA with an SC-based multiplication, where the problem of accuracy and latency are both improved using parallel stochastic sequence generators and leading zero shifters. In addition, with the flexible connections among PEs, the high-accuracy operation can be easily achieved by combing neighbor PEs without switching costs like power-gating. Compared to the state-of-the-art approximate computing design of CGRA, our proposed CGRA has 16% more energy reduction and 34% energy efficiency improvement while keeping high configuration flexibility.","Title: RF-CGRA: A Routing-Friendly CGRA with Hierarchical Register Chains\nYear: 2022\n\nAbstract: CGRAs are promising architectures to accelerate domain-specific applications as they combine high energy-efficiency and flexibility. With either isolated register files (RFs) or link-consuming distributed registers in each processing element (PE), existing CGRAs are all not friendly to data routing for data-flow graphs (DFGs) with a high edge/node ratio since there are many multi-cycle dependences. To this end, this paper proposes a Routing-Friendly CGRA (RF-CGRA) where hierarchical (intra-PE or inter-PE) register chains could be flexibly (wide range of chain length) and compactly (consuming fewer links among PEs) achieved for data routing, resulting in a new mapping problem that requires the improvement of a compiler. Experimental results show that RF-CGRA gets 1.19× performance and 1.14× energy efficiency of the state-of-the-art CGRA with single-cycle multi-hop connections (HyCUBE) while keeping a moderate compilation time.","Title: Degradation analysis with nonlinear exponential-dispersion process: Bayesian offline and online perspectives\nYear: 2022\n\nAbstract: Exponential-dispersion (ED) process has been recently introduced and demonstrated as a promising degradation model, which can include classical Wiener, gamma, and inverse Gaussian (IG) processes as special cases. However, most related studies are based on offline and point estimation methods, which limit their capability for uncertainty quantification and online update inference. In this paper, nonlinear ED process models equipped with Bayesian offline and online inference methods are presented. Tweedie ED process models are studied for degradation analysis with accelerated factors and unit-to-unit variability. Bayesian offline method based on NO-U-Turn sampler (NUTS) algorithm and Bayesian online method based on particle filter are developed, respectively. The offline method is presented to enhance the ED process based degradation analysis with uncertainty quantification. The online method is developed for the applications with limited storage and computing resources, for which degradation observations are analyzed on-the-fly with improved efficiency. Effectiveness and characteristics of the proposed methods are demonstrated through a simulation study and two case studies."],"string":"[\n \"Title: A Novel Image Classification Method Based on Double Manifold Learning\\nYear: 2010\\n\\nAbstract: To solve the two-class classification problem existing in semantic-based image understanding, a novel classification method based on double manifold learning is proposed, which can transform the classification problem from a high-dimensional data space to a feature space with lower dimensionality. Two manifolds with different intrinsic dimensionalities will be first established separately, according to the significant differences between the positive samples and the negative ones, where globular neighborhood-based locally linear embedding (GNLLE) algorithm is adopted to implement dimensionality reduction and meantime unsupervised clustering. Then the aggregation center of each manifold is calculated, taking into account the grouping characteristics of similar samples. Furthermore, a new classifier is constructed for a double manifold learning model via distance companion. Finally experiments indicate that our method, which can be easily extended to multi-classification manifold learning, will not only reflect the topological structure of the whole data more precisely, but also achieve performance of classification more efficiently.\",\n \"Title: XML based interactive video and data services over cable\\nYear: 2000\\n\\nAbstract: The growing use of cable to broadcast digital TV programs provides the opportunity for delivering digital data services. Multi-dimensional information can be inserted into plain video streams. The information could be stock data, weather forecast or electronic programs guide. In our project, we embed the data which are related to the objects in video and provide more information about those objects. This is much like the hyperlinks in web pages. it's useful in such areas as advertising, distance education and entertainment This paper concisely describes the in-progress research of the process of data authoring and the use of XML to solve some problems within it.\",\n \"Title: A novel intelligent strategy for improving measurement precision of FOG\\nYear: 2000\\n\\nAbstract: This paper discusses a neural network-based strategy for reducing the existing errors of fiber-optic gyroscope (FOG). A series-single-layer neural network, which is composed of two single-layer networks in series, is presented for eliminating random noises. This network has simpler architecture, faster learning speed, and better performance compared to conventional backpropagation (BP) networks. A...\",\n \"Title: A novel hybrid model for image classification\\nYear: 2011\\n\\nAbstract: Recently, biological intelligent computing gains more and more attention in analysing large-scale real world datasets. Because the performance of the support vector machine (SVM) classifier is always degraded by poor feature subsets and inappropriate parameters for training, an improved quantum-behaved particle swarm optimisation (IQPSO) is introduced to optimise the features and parameters synchronically, aiming to improve the generalisation of the SVM classifier. That is, a novel hybrid image classification model by combing SVM and IQPSO, called as IQPSO_SVM is presented in this paper. Experimental results show that the proposed IQPSO_SVM improves the classification accuracy greatly compared to the traditional SVM with grid search, and outperforms such SVM based on genetic algorithm (GA_SVM) without accuracy loss.\",\n \"Title: Linear grouping using orthogonal regression\\nYear: 2006\\n\\nAbstract: A new method to detect different linear structures in a data set, called Linear Grouping Algorithm (LGA), is proposed. LGA is useful for investigating potential linear patterns in data sets, that is, subsets that follow different linear relationships. LGA combines ideas from principal components, clustering methods and resampling algorithms. It can detect several different linear relations at once. Methods to determine the number of groups in the data are proposed. Diagnostic tools to investigate the results obtained from LGA are introduced. It is shown how LGA can be extended to detect groups characterized by lower dimensional hyperplanes as well. Some applications illustrate the usefulness of LGA in practice.\",\n \"Title: Semantic Image Retrieval Based on Multiple-Instance Learning\\nYear: 2010\\n\\nAbstract: Image semantics have received more and more attention because of the huge gap between the low-level features and the semantics. Semantic image retrieval is a challenging problem and became a research focus. This paper presents a semantic image retrieval approach based on multiple-instance learning. In multiple-instance learning, the training samples are bags composed of instances without labels. The proposed approach realizes the mapping from low-level features to simple semantics and the mapping from simple semantics to compound semantics by means of multiple-instance learning. The obtained semantics are used in semantic image retrieval. The experiment results show that the proposed approach is able to process semantic image retrieval more reliably and more effectively.\",\n \"Title: Parallel Matrix Multiplication Algorithm Based on Vector Linear Combination Using MapReduce\\nYear: 2013\\n\\nAbstract: Matrix multiplication is used in a variety of applications. It requires a lot of computation time especially for large-scale matrices. Parallel processing is a good choice for matrix multiplication operation. To overcome the efficiencies of existing algorithms for parallel matrix multiplication, a matrix multiplication processing scheme based on vector linear combination (VLC) was presented. The VLC scheme splits the matrix multiplication procedure into two steps. The first step obtains the weighted vectors by scalar multiplication. The second step gets the final result through a linear combination of the weighted vectors with identical row numbers. We present parallel matrix multiplication implementations using MapReduce (MR) based on VLC scheme and explain in detail the MR job. The map method receives the matrix input and generates intermediate (key, value) pairs according to the VLC scheme requirement. The reduce method conducts the scalar multiplication and vectors summation. In the end, the reduce method outputs the result in the way of row vector. Then performance theoretical analysis and experiment result comparing with other algorithms are proposed. Algorithm presented in this paper needs less computation time than other algorithms. Finally, we conclude the paper and propose future works.\",\n \"Title: A Novel Micro Air Vehicle with Flexible Wing Integrated with On-board Electronic Devices\\nYear: 2008\\n\\nAbstract: This paper presents an electrically powered micro air vehicle (MAV) with a flexible wing integrated with on-board electronic components that is built at Tsinghua University. The low aspect ratio wing, adopting the airfoil of S5010 and Zimmerman shape, is made up of a flexible printed circuit membrane (FPCM) that covers a thin carbon fiber skeleton. The real MAV prototype is tested in a low-speed wind tunnel in order to evaluate its aerodynamic characteristics. The comparing experiments are conducted on the flexible wing and its rigid counterpart with the same size and the same wing shape to illustrate the aerodynamic advantages of the flexible wing. The results of the wind tunnel experiments indicate that the flexible wing has a larger angle of stall, bigger maximum lift coefficient than the rigid one. However, the lift-drag ratio of the flexible wing varies in a complex way because the flexible wing also increases the drag with the lift growth. The FPCM functions as both the skin of the aircraft wing and the supporting substrate for the electronic components, such as micro hot-film flow speed sensors that are used to determine 3 fundamental flight parameters: air speed, angle of attack and sideslip angle. In addition, most of the signal processing circuits is distributed on the FPCM, which remarkably reduces the autopilot load. The dimensions of a homemade autopilot that is separately installed in the fuselage are 35times20times12 mm with the weight of 6 g. Through experiments of real flights, the turning, climbing, maneuverability and wind resistant ability of the MAV are tested. The flight results show that the MAV can fly with good stability and maneuverability.\",\n \"Title: Image Classification Approach Based on Manifold Learning in Web Image Mining\\nYear: 2009\\n\\nAbstract: Automatic image classification is a challenging research topic in Web image mining. In this paper, we formulate image classification problem as the calculation of the distance measure between training manifold and test manifold. We propose an improved nonlinear dimensionality reduction algorithm based on neighborhood optimization, not only to decrease feature dimensionality but also to transform the problem from high-dimensional data space into low-dimensional feature space. Considering that the images in most real-world applications have large diversities within category and among categories, we propose a new scheme to construct a set of training manifolds each representing one semantic category and partition each nonlinear manifold into several linear sub-manifolds via region growing. Moreover, to further reduce computational complexity, each sub-manifold is depicted by aggregation center. Experimental results on two Web image sets demonstrate the feasibility and effectiveness of the proposed approach.\",\n \"Title: Estimating the error variance after a pre-test for an interval restriction on the coefficients\\nYear: 2011\\n\\nAbstract: This paper considers the estimation of the error variance after a pre-test of an interval restriction on the coefficients. We derive the exact finite sample risks of the interval restricted and pre-test estimators of the error variance, and examine the risk properties of the estimators to model misspecification through the omission of relevant regressors. It is found that the pre-test estimator performs better than the interval restricted estimator in terms of the risk properties in a large region of the parameter space; moreover, its risk performance is more robust with respect to the degrees of model misspecification. Furthermore, we propose a bootstrap procedure for estimating the risks of the estimators, to overcome the difficulty of computing the exact risks.\",\n \"Title: Constructing a Novel Pos-neg Manifold for Global-Based Image Classification.\\nYear: 2013\\n\\nAbstract: For the task of global-based image classification, we construct an image manifold, i.e., a pos-neg manifold, based on the solving strategies of two-class classification problem, which includes a positive sub-manifold and a negative one. We also present an improved globular neighborhood based locally linear embedding (an improved GNLLE) algorithm, fully taking account of the big differences between the positive and negative category images, thus the data distance calculation defined in the high-dimensional space can be translated into the one on the image manifold with lower dimensionality. Moreover, to simplify the distance measure between two nonlinear sub-manifolds, we put forward a clustering-based method to determine a manifold center for each sub-manifold. Experimental results on the real-world Web images show that the proposed method can improve the classification performance significantly. © Springer-Verlag 2013.\",\n \"Title: New Approach for Embedded Computer Numeric Control Development\\nYear: 2008\\n\\nAbstract: After analyzing the shortcomings of traditional code-centric development process for Embedded Computer Numeric Control (CNC), this paper presents a new approach: Embedded cNc Development based on modEl Driven (ENDED) which enjoys the advantages of model-driven development (MDD) and domain specific modeling (DSM). This approach is a model-based methodology which includes three parts: construction of domain modeling language, model transformation, code auto-generation from domain model. Multi-view based meta-modeling method was employed in the first step of ENDED to construct the CNC modeling language. During the model transformation part, three requirements of model transformation were proposed and corresponding processing strategies were elaborated. In the last part, code auto generator based on domain library to improve the productivity was described in details and an illustrative example was tested to show the feasibility of ENDED.\",\n \"Title: A flexible flow sensor system and its characteristics for fluid mechanics measurements.\\nYear: 2009\\n\\nAbstract: In this paper, we present a novel micromachined hot-film flow sensor system realized by a technique using a film depositing processes and incorporating a standard printed circuit. Sensor electrodes and electronic circuits are preprinted on a flexible substrate of polyimide (PI), i.e., a flexible printed circuit board (FPCB). The sensing element, which is made of Cr/Ni/Pt with a temperature coefficient of resistance around 2,000 ppm/K, is fabricated on the FPCB by either magnetron sputtering technology or pulsed laser deposition (PLD). The sensor can be packed efficiently at high-density and integrated with signal processing circuits without additional pads. A simple fabrication process using mature technique and materials selection guarantees that the time and costs are greatly reduced. Both steady-state and transient characteristics of the sensors are experimentally tested, and the results presented to validate the effectiveness of the sensors.\",\n \"Title: Development of Micro Air Vehicle Based on Aerodynamic Modeling Analysis in Tunnel Tests\\nYear: 2005\\n\\nAbstract: This paper presents development of an electrically powered Micro Air Vehicle (MAV) prototype based on aerodynamic analysis in wind tunnel and water tunnel tests. Two airframe models in triangle and square wing planforms, each with a wingspan of 100mm, are analyzed with a small-scale low speed wind tunnel to examine the practical characteristics at the low Reynolds number. The test in a water tunnel is further carried out to investigate the relationship between the vortex aerofoil design and turbulences created. The testing results show that the triangle wing aerofoil appears greater maximum lift coefficient and little occurrence of vortex and turbulences. Based on the verified wing planform in the tunnel tests, a MAV prototype was further designed and fabricated, with successful tests in the real flight.\",\n \"Title: Collision-free Path Planning and Trajectory Generation for MAVs Flying in Urban Terrain\\nYear: 2006\\n\\nAbstract: This paper presents an optimal algorithm for finding collision-free path and trajectory for microair vehicles (MAVs) in urban terrain where multiple ground obstacles are distributed. Regarding vertices of polygonal obstacles as input points of the Delaunay triangulations, a Delaunay-based path planning is proposed to determine an optimal waypoint path while considering criterions of minimum fuel expenditure and collision risk. A trajectory generation method with corresponding optimal constraints is further developed to yield feasible fly trajectory along the planned path. The off-line pre-planning and on-line updated planning are integrated to enhance autonomy of vehicles flying in dangerous situations, with tight maneuvering and operational capability. Simulation results of a mission scenario are finally presented to demonstrate effectiveness of the proposed approach\",\n \"Title: Mining item-item and between-set correlated association rules.\\nYear: 2011\\n\\nAbstract: To overcome the failure in eliminating suspicious patterns or association rules existing in traditional association rules\\n mining, we propose a novel method to mine item-item and between-set correlated association rules. First, we present three\\n measurements: the association, correlation, and item-set correlation measurements. In the association measurement, the all-confidence\\n measure is used to filter suspicious cross-support patterns, while the all-item-confidence measure is applied in the correlation\\n measurement to eliminate spurious association rules that contain negatively correlated items. Then, we define the item-set\\n correlation measurement and show its corresponding properties. By using this measurement, spurious association rules in which\\n the antecedent and consequent item-sets are negatively correlated can be eliminated. Finally, we propose item-item and between-set\\n correlated association rules and two mining algorithms, I&ISCoMine_AP and I&ISCoMine_CT. Experimental results with synthetic\\n and real retail datasets show that the proposed method is effective and valid.\",\n \"Title: Smart Wheelchair Navigation Based on User's Gaze on Destination\\nYear: 2010\\n\\nAbstract: Designing intelligent navigation systems is a challenging task because environmental uncertainty may prevent mission accomplishment. This paper presents a smart wheelchair navigation system using information from the goal position indicated by the user's gaze. The system tracks the user's head with a web camera to determine the direction where the gaze is fixed. Then, it detects the area that the user gazed at, in the panoramic image obtained from an omni-directional camera and sets the area as the destination. Once the destination is fixed, navigation starts by rotating the wheelchair heading to the destination by visual servoing with SURF descriptors around the destination area. During maneuver, a laser range sensor scans critical wheelchair's area for obstacles. If detected, their distribution is analyzed to generate steering commands for avoiding them and eventually ensuring the wheelchair's pose towards the goal. Experimental operation in indoor environments has shown the feasibility of the proposed system.\",\n \"Title: A wireless portable system with microsensors for monitoring respiratory diseases.\\nYear: 2012\\n\\nAbstract: A wireless portable monitoring system for respiratory diseases using microsensors is proposed. The monitoring system consists of two sensor nodes integrating with Bluetooth transmitters that measure user's respiratory airflow, blood oxygen saturation, and body posture. The utility of micro-hot-film flow sensor makes the monitor can acquire comprehensive respiration parameters which are useful for ...\",\n \"Title: A two-level strategy for segmenting center of interest from pictures\\nYear: 2011\\n\\nAbstract: Segmenting center of interests (COIs) from pictures is an important but highly challenging problem for researchers in computer vision and image processing. The capability of understanding the meanings of pictures by computers can lead to breakthroughs in a wide range of applications including Web image search and online picture-sharing communities. In this paper, a two-level strategy is presented, which consists of a rough segmentation stage and a fine segmentation stage. In the first level, a picture is partitioned into four regions by using a block clustering method based on color and texture features, and the COI within the picture is distinguished from the background according to the principles of photographic composition. This stage aims to determine the approximate region of the target. In the second level, a novel active contour model is established based on shape information and vector method, where the image energy is defined by a hue gradient and the external energy is generated from either a triangular inner force or a supplementary force. This stage tries to extract the boundary of the target accurately. Experimental results on photos downloaded from the Internet show the feasibility and effectiveness of the proposed method.\",\n \"Title: Aircraft aerodynamic parameter detection using micro hot-film flow sensor array and BP neural network identification.\\nYear: 2012\\n\\nAbstract: Air speed, angle of sideslip and angle of attack are fundamental aerodynamic parameters for controlling most aircraft. For small aircraft for which conventional detecting devices are too bulky and heavy to be utilized, a novel and practical methodology by which the aerodynamic parameters are inferred using a micro hot-film flow sensor array mounted on the surface of the wing is proposed. A back-propagation neural network is used to model the coupling relationship between readings of the sensor array and aerodynamic parameters. Two different sensor arrangements are tested in wind tunnel experiments and dependence of the system performance on the sensor arrangement is analyzed.\",\n \"Title: Micro thermal flow sensors/systems on flexible PCB and extensive applications\\nYear: 2013\\n\\nAbstract: We demonstrate our researches on developing micro thermal flow sensors by depositing nano metallic films on flexible substrates for detecting surface flow. The fabrication of the sensors is incorporating standard printed circuit technique with micromachining deposit/sputter, which takes advantages of low cost, easy fabrication, easy packaging and integrating sensors with processing circuits. The applications using the sensors to detect airflow around air vehicles, underwater wall shear stress, and to measure respiratory flow for monitoring and diagnosing respiratory diseases are also presented.\",\n \"Title: Modeling and experimental study on characterization of micromachined thermal gas inertial sensors.\\nYear: 2010\\n\\nAbstract: Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication.\",\n \"Title: Research on the distribution of geomagnetic daily variation along some station chains in China\\nYear: 2011\\n\\nAbstract: The temporal and spatial distribution of Sq(H)in China was analyzed based on the geomagnetic digitized data from the geomagnetic observation network.It was found that:(1)there was obvious prenoon-postnoon asymmetry of Sq(H)in Summer and Equinox.(2)in Summer,Equinox and Winter,the averaged focus position of Sq were 27 ° N,29 ° N and 35 ° N respectively.But in a single quiet day,the focus of Sq might appear in the north of 50 ° N and in the south of 19 ° N.(3)there were some special behavior of the Sq(H)distributions such as the latitudinal trend inconsistencies in two longitudinal chain,the reverse of Sq(H)variations in the same latitudinal chain and the increase(decrease)of the daily ranges from east to west.All these demonstrated that there might be latitudinal migration of the Sq focus or changes in current intensity during the longitudinal migration of Sq focus from east to west.\",\n \"Title: Testing inequality constraints in a linear regression model with spherically symmetric disturbances.\\nYear: 2014\\n\\nAbstract: This paper develops a Wald statistic for testing the validity of multivariate inequality constraints in linear regression models with spherically symmetric disturbances, and derive the distributions of the test statistic under null and nonnull hypotheses. The power of the test is then discussed. Numerical evaluations are also carried out to examine the power performances of the test for the case in which errors follow a multivariate student-t (Mt) distribution.\",\n \"Title: Adaptive mode assignment in performance-critical cyber-physical systems\\nYear: 2015\\n\\nAbstract: Distributed cyber-physical systems(CPS) deployed in performance-critical applications are imposed stringent constraints such as the real-time requirement and energy consumption budget. However, the performance of CPS is inevitably undermined by various physical uncertainties, which include stochastic environment noise and dynamics of the physical phenomenon. Both of those uncertainties might lead to overload and the power overconsumption as task execution times are unpredictable. While recent feedback control scheduling have shown promise to meet the end-to-end deadlines by adaptively adjusting the task loading rate, little work has focused on both the system service rate and the CPU execution modes as a whole to minimize the system power consumption. This paper presents a feedback control based algorithm that adaptively maintains desired task service rate for real-time requirement while minimizes the power consumption by assigning proper execution modes on processor for each node. The theoretic analysis and numerous simulations demonstrate that the proposed scheme can provide robust real-time guarantees and reduce the power consumption when the task workload vary significantly at run-time.\",\n \"Title: The design of Ambisonic reproduction system based on dynamic gain parameters\\nYear: 2014\\n\\nAbstract: This paper describes a design approach of Ambisonic reproduction system based on dynamic gain parameters (DGP). In the conventional approaches, the fixed gain parameters are often optimized to minimize the overall objective function for whole 360° sound stage. The proposed approach has an advantage that the gain parameters vary with angles of source objects. The problem of optimization tradeoff among different angles is overcome by DGP, which achieves an optimal solution in each position. Source localizations of the B-Format signals were estimated in frequency bands in order to match the corresponding gain parameters. For the synthesized signals, the process was simplified by the given spatial information. Using the head-related transfer function (HRTF) analysis, the proposed approach was found to be significantly better than reference approaches in interaural time difference (ITD) and interaural level difference (ILD).\",\n \"Title: The design of HOA irregular decoders based on the optimal symmetrical virtual microphone response\\nYear: 2014\\n\\nAbstract: Ambisonic decoder for irregular speaker arrays could be derived by optimization techniques. In terms of higher order reproduction system, the optimization program is hard to be guided to a large number of decoder coefficients. This paper describes a new method for higher order decoder based on the optimal symmetrical virtual microphone response (OSVMR). In the proposed method, the number of the decoder coefficients is reduced and the optimal symmetrical polar pattern of speaker feeds is obtained. The binaural evaluation demonstrates that the proposed method is found to be significantly better than reference methods on interaural time difference (ITD) and interaural level difference (ILD).\",\n \"Title: Integration of micro sensors with mobile devices for monitoring vital signs of sleep apnea patients\\nYear: 2014\\n\\nAbstract: Body Sensor Networks (BSNs) integrating micro sensor nodes with wireless communication are becoming flourishing in medical applications. This paper demonstrates a BSN-based portable monitor integrating micro sensors with mobile devices for monitoring and diagnosing obstructive sleep apnea syndrome (OSAS) at home. The system uses a micro hot-film flow sensor to detect respiratory flow, uses tri-axis micro accelerometer to detect body posture and motion intensity, and uses a micro photoelectric sensor to detect oxygen saturation of blood. The real-time vital signs are detected and transmitted wirelessly to a mobile device. The transmitted data are processed and analyzed in the mobile device and can be further transmitted to a remote medical center and physicians through mobile cellular networks or Internet for comprehensively analyzing, assessing, and diagnosing to the diseases.\",\n \"Title: The design of ambisonics decoders for irregular speaker array conforming to subjective perception\\nYear: 2014\\n\\nAbstract: An analysis of previously derived Ambisonics decoders shows that the mid-high frequency performance of these decoders has poor agreement with subjective perception, since the optimized decoder coefficients could not well meet the objectives developed by the energy vector, and the polar pattern of speaker feeds is suboptimal. In this paper, new objectives are added to fitness function for the optimal speaker response, and the sum of weighted rations genetic algorithm is applied to search a good set of decoder coefficients to meet all the objectives. The decoder of an example application of ITU-4.0 speaker array exhibits a significant improvement in localization performance at the rear of the listeners. In addition, the binaural evaluation demonstrates that the performance of the proposed decoder better conform to the subjective perception.\",\n \"Title: A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.\\nYear: 2016\\n\\nAbstract: Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 x 38 x 25 mm(3). The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 x 10(4) /cm(3) and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices.\",\n \"Title: SimRank computation on uncertain graphs\\nYear: 2016\\n\\nAbstract: SimRank is a similarity measure between vertices in a graph, which has become a fundamental technique in graph analytics. Recently, many algorithms have been proposed for efficient evaluation of SimRank similarities. However, the existing SimRank computation algorithms either overlook uncertainty in graph structures or is based on an unreasonable assumption (Du et al). In this paper, we study SimRank similarities on uncertain graphs based on the possible world model of uncertain graphs. Following the random-walk-based formulation of SimRank on deterministic graphs and the possible worlds model of uncertain graphs, we define random walks on uncertain graphs for the first time and show that our definition of random walks satisfies Markov's property. We formulate the SimRank measure based on random walks on uncertain graphs. We discover a critical difference between random walks on uncertain graphs and random walks on deterministic graphs, which makes all existing SimRank computation algorithms on deterministic graphs inapplicable to uncertain graphs. To efficiently compute SimRank similarities, we propose three algorithms, namely the baseline algorithm with high accuracy, the sampling algorithm with high efficiency, and the two-phase algorithm with comparable efficiency as the sampling algorithm and about an order of magnitude smaller relative error than the sampling algorithm. The extensive experiments and case studies verify the effectiveness of our SimRank measure and the efficiency of our SimRank computation algorithms.\",\n \"Title: Gene Expression Programming With Multiple Chromosomes\\nYear: 2011\\n\\nAbstract: Gene expression programming (GEP) has been widely used in the areas of pattern recognition and knowledge discovery, however, when dealing with complicated problems, it is very time-consuming and the number of generations is large. In order to overcome these drawbacks, this paper proposes a multi-chromosomes GEP algorithm (MC-GEP). Firstly, the individual is composed of multiple chromosomes, each chromosome consists of one or more genes. Secondly, the expression of each chromosome or combinations of several chromosomes may be chosen to indicate the individual. Finally, chromosome recombination is changed and performed orderly like meiosis. Experimental results show that MC-GEP can reduce the running time and the number of generations with respect to the GEP.\",\n \"Title: Top-k Reliability Search on Uncertain Graphs\\nYear: 2015\\n\\nAbstract: Uncertain graphs have been widely used to represent graph data with inherent uncertainty in structures. Reliability search is a fundamental problem in uncertain graph analytics. This paper studies a new problem, the top-k reliability search problem on uncertain graphs, that is, finding k vertices v with the highest reliabilities of connections from a source vertex s to v. Note that the existing algorithm for the threshold-based reliability search problem is inefficient for the top-k reliability search problem. We propose a new algorithm to efficiently solve the top-k reliability search problem. The algorithm adopts two important techniques, namely the BFS sharing technique and the offline sampling technique. The BFS sharing technique exploits overlaps among different sampled possible worlds of the input uncertain graph and performs a single BFS on all possible worlds simultaneously. The offline sampling technique samples possible worlds offline and stored them using a compact structure. The algorithm also takes advantages of bit vectors and bitwise operations to improve efficiency. Moreover, we generalize the top-k reliability search problem to the multi-source case and show that the multi-source case of the problem can be equivalently converted to the single-source case of the problem. Extensive experiments carried out on both real and synthetic datasets verify that the optimized algorithm outperforms the baselines by 1 -- 2 orders of magnitude in execution time while achieving comparable accuracy. Meanwhile, the optimized algorithm exhibits linear scalability with respect to the size of the input uncertain graph.\",\n \"Title: System Error Compensation Methodology Based on a Neural Network for a Micromachined Inertial Measurement Unit.\\nYear: 2016\\n\\nAbstract: Errors compensation of micromachined-inertial-measurement-units (MIMU) is essential in practical applications. This paper presents a new compensation method using a neural-network-based identification for MIMU, which capably solves the universal problems of cross-coupling, misalignment, eccentricity, and other deterministic errors existing in a three-dimensional integrated system. Using a neural network to model a complex multivariate and nonlinear coupling system, the errors could be readily compensated through a comprehensive calibration. In this paper, we also present a thermal-gas MIMU based on thermal expansion, which measures three-axis angular rates and three-axis accelerations using only three thermal-gas inertial sensors, each of which capably measures one-axis angular rate and one-axis acceleration simultaneously in one chip. The developed MIMU (100 x 100 x 100 mm(3)) possesses the advantages of simple structure, high shock resistance, and large measuring ranges (three-axes angular rates of +/- 4000 degrees/s and three-axes accelerations of +/- 10 g) compared with conventional MIMU, due to using gas medium instead of mechanical proof mass as the key moving and sensing elements. However, the gas MIMU suffers from cross-coupling effects, which corrupt the system accuracy. The proposed compensation method is, therefore, applied to compensate the system errors of the MIMU. Experiments validate the effectiveness of the compensation, and the measurement errors of three-axis angular rates and three-axis accelerations are reduced to less than 1% and 3% of uncompensated errors in the rotation range of +/- 600 degrees/s and the acceleration range of +/- 1 g, respectively.\",\n \"Title: Self-Tuning Fully-Connected PID Neural Network System for Distributed Temperature Sensing and Control of Instrument with Multi-Modules.\\nYear: 2016\\n\\nAbstract: High integration of multi-functional instruments raises a critical issue in temperature control that is challenging due to its spatial-temporal complexity. This paper presents a multi-input multi-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating the temperature environment within a multi-module instrument. The smart system ensures that the internal temperature of the instrument converges to a target without the need of a system model, thus making the control robust. The system consists of a fully-connected proportional-integral-derivative (PID) neural network (FCPIDNN) and an on-line self-tuning module. The experimental results show that the presented system can effectively control the internal temperature under various mission scenarios, in particular, it is able to self-reconfigure upon actuator failure. The system provides a new scheme for a complex and time-variant MIMO control system which can be widely applied for the distributed measurement and control of the environment in instruments, integration electronics, and house constructions.\",\n \"Title: Towards efficient top-k reliability search on uncertain graphs.\\nYear: 2017\\n\\nAbstract: Uncertain graph has been widely used to represent graph data with inherent uncertainty in structures. Reliability search is a fundamental problem in uncertain graph analytics. This paper investigates on a new problem with broad real-world applications, the top-k reliability search problem on uncertain graphs, that is, finding the k vertices v with the highest reliabilities of connections from a source vertex s to v. Note that the existing algorithm for the threshold-based reliability search problem is inefficient for the top-k reliability search problem. We propose a new algorithm to efficiently solve the top-k reliability search problem. The algorithm adopts two important techniques, namely the BFS sharing technique and the offline sampling technique. The BFS sharing technique exploits overlaps among different sampled possible worlds of the input uncertain graph and performs a single BFS on all possible worlds simultaneously. The offline sampling technique samples possible worlds offline and stores them using a compact structure. The algorithm also takes advantages of bit vectors and bitwise operations to improve efficiency. In addition, we generalize the top-k reliability search problem from single-source case to the multi-source case and show that the multi-source case of the problem can be equivalently converted to the single-source case of the problem. Moreover, we define two types of the reverse top-k reliability search problems with different semantics on uncertain graphs. We propose appropriate solutions for both of them. Extensive experiments carried out on both real and synthetic datasets verify that the optimized algorithm outperforms the baselines by 1---2 orders of magnitude in execution time while achieving comparable accuracy. Meanwhile, the optimized algorithm exhibits linear scalability with respect to the size of the input uncertain graph.\",\n \"Title: Elimination of Drifts in Long-Duration Monitoring for Apnea-Hypopnea of Human Respiration.\\nYear: 2016\\n\\nAbstract: This paper reports a methodology to eliminate an uncertain baseline drift in respiratory monitoring using a thermal airflow sensor exposed in a high humidity environment. Human respiratory airflow usually contains a large amount of moisture (relative humidity, RH >85%). Water vapors in breathing air condense gradually on the surface of the sensor so as to form a thin water film that leads to a significant sensor drift in long-duration respiratory monitoring. The water film is formed by a combination of condensation and evaporation, and therefore the behavior of the humidity drift is complicated. Fortunately, the exhale and inhale responses of the sensor exhibit distinguishing features that are different from the humidity drift. Using a wavelet analysis method, we removed the baseline drift of the sensor and successfully recovered the respiratory waveform. Finally, we extracted apnea-hypopnea events from the respiratory signals monitored in whole-night sleeps of patients and compared them with golden standard polysomnography (PSG) results.\",\n \"Title: Highly Sensitive Hot-Wire Anemometry Based on Macro-Sized Double-Walled Carbon Nanotube Strands.\\nYear: 2017\\n\\nAbstract: This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs) as sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT) strands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor is demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by suspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of silver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive TCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current was applied between the two prongs. This sensor can evidently respond to flow rate, and requires only several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor has better sensitivity than the Pt-coated DWCNT sensor.\",\n \"Title: A Case Study of Land-Surface-Temperature Impact from Large-Scale Deployment of Wind Farms in China from Guazhou.\\nYear: 2016\\n\\nAbstract: The wind industry in China has experienced a rapid expansion of capacity after 2009, especially in northwestern China, where the China's first 10 GW-level wind power project is located. Based on the analysis from Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data for period of 2005-2012, the potential LST impacts from the large-scale wind farms in northwestern China's Guazhou are investigated in this paper. It shows the noticeable nighttime warming trends on LST over the wind farm areas relative to the nearby non-wind-farm regions in Guazhou and that the nighttime LST warming is strongest in summer (0.51 degrees C/8 years), followed by autumn (0.48 degrees C/8 years) and weakest in winter (0.38 degrees C/8 years) with no warming trend observed in spring. Meanwhile, the quantitative comparison results firstly indicate that the nighttime LST warming from wind farm areas are less than those from the urban areas in this work.\",\n \"Title: Micromachined Fluid Inertial Sensors.\\nYear: 2017\\n\\nAbstract: Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri- axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern.\",\n \"Title: A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles.\\nYear: 2017\\n\\nAbstract: Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30-500 nm, number concentration in range of 5 x 10(2)-5 x 10(7) / cm(3). The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles.\",\n \"Title: A vessel segmentation method for low contrast CT angiography image.\\nYear: 2016\\n\\nAbstract: CT angiography image vessel segmentation technique plays a critical role in many practical applications such as diagnosis of diseases and surgical planning. Blood vessels after angiography are often defective in low contrast and high noise due to individual differences and limitations of imaging device. A set of segmentation methods has been proposed for such data feature, which firstly adopts combination of average filtering with high frequency emphasizes filtering enhancement algorithms to perform enhancement preprocessing on the original image, thereby enhancing the contrast ratio of blood vessels and surrounding area; secondly, it performs vessel extraction on the enhanced data using region growth algorithm to obtain the segmentation data of richer vessel branches. Experimental results prove that the segmentation approach proposed here can accurately perform vessel segmentation and effectively avoid incorrect segmentation with better robustness.\",\n \"Title: Online Multi-threshold Learning with Imbalanced Data Stream.\\nYear: 2017\\n\\nAbstract: This paper addresses the imbalanced data problem in an online fashion based on multi-threshold learning. The majority of existing works on processing large-scale imbalanced data stream assume a prior distribution of data based on a training dataset, while we consider a more challenging setting without any assumption of the prior, and propose an online multi-threshold learning (OMTL) method by simultaneously learning multiple classifiers with different threshold based on F-measure incremental updating. The proposed approach shows its potentials on recent benchmark datasets compared to previous cost-sensitive and threshold fine-tuning based online learning algorithms.\",\n \"Title: A hybrid intra refresh and reference selection scheme for mobile video coding\\nYear: 2017\\n\\nAbstract: Real-time video performance is difficult to guarantee under mobile communication environments characterized by loss-probability-varying transmission channel, heterogeneous networks, and various mobile devices of different access capabilities. In this paper, a novel attention-based network-aware robust video coding scheme mixing adaptive intra refresh with reference picture selection is proposed to improve the visual experience for mobile video. This method unifies human visual attention, state information of wireless channel and hybrid refresh tools to realize optimum bitrate allocation so that uneven robustness for attentive image regions against the packet loss can be readily accomplished. Further, a set of tools serving for evaluating the refresh regions, refresh modes and reference decision are developed, considering a balance among the coding efficiency, error resilience and user experience. Experiments on H.264 show that the proposed scheme provides a much better subjective feeling than traditional refresh methods when compressed video is delivered over wireless channels.\",\n \"Title: A FPGA-Based, Granularity-Variable Neuromorphic Processor and Its Application in a MIMO Real-Time Control System.\\nYear: 2017\\n\\nAbstract: Artificial Neural Networks (ANNs), including Deep Neural Networks (DNNs), have become the state-of-the-art methods in machine learning and achieved amazing success in speech recognition, visual object recognition, and many other domains. There are several hardware platforms for developing accelerated implementation of ANN models. Since Field Programmable Gate Array (FPGA) architectures are flexible and can provide high performance per watt of power consumption, they have drawn a number of applications from scientists. In this paper, we propose a FPGA-based, granularity-variable neuromorphic processor (FBGVNP). The traits of FBGVNP can be summarized as granularity variability, scalability, integrated computing, and addressing ability: first, the number of neurons is variable rather than constant in one core; second, the multi-core network scale can be extended in various forms; third, the neuron addressing and computing processes are executed simultaneously. These make the processor more flexible and better suited for different applications. Moreover, a neural network-based controller is mapped to FBGVNP and applied in a multi-input, multi-output, (MIMO) real-time, temperature-sensing and control system. Experiments validate the effectiveness of the neuromorphic processor. The FBGVNP provides a new scheme for building ANNs, which is flexible, highly energy-efficient, and can be applied in many areas.\",\n \"Title: Diversified Coherent Core Search on Multi-Layer Graphs.\\nYear: 2018\\n\\nAbstract: Mining dense subgraphs on multi-layer graphs is an interesting problem, which has witnessed lots of applications in practice. To overcome the limitations of the quasi-clique-based approach, we propose d-coherent core (d-CC), a new notion of dense subgraph on multi-layer graphs, which has several elegant properties. We formalize the diversified coherent core search (DCCS) problem, which finds kd-CCs that can cover the largest number of vertices. We propose a greedy algorithm with an approximation ratio of \\n \\n \\n \\n $$1 - 1/e$$\\n \\n \\n \\n and two search algorithms with an approximation ratio of 1/4. Furthermore, we propose some optimization techniques to further speed up the algorithms. The experiments verify that the search algorithms are faster than the greedy algorithm and produce comparably good results as the greedy algorithm in practice. As opposed to the quasi-clique-based approach, our DCCS algorithms can fast detect larger dense subgraphs that cover most of the quasi-clique-based results.\",\n \"Title: SimRank on Uncertain Graphs.\\nYear: 2017\\n\\nAbstract: SimRank is a similarity measure between vertices in a graph. Recently, many algorithms have been proposed to efficiently evaluate SimRank similarities. However, the existing algorithms either overlook uncertainty in graph structures or depends on an unreasonable assumption. In this paper, we study SimRank on uncertain graphs. Following the random-walk-based formulation of SimRank on deterministic ...\",\n \"Title: Predicting the quality of online health expert question-answering services with temporal features in a deep learning framework.\\nYear: 2018\\n\\nAbstract: Currently, online health expert question-answering (HQA) services are the most popular services for health consumers to search online health information due to their convenience and the cost-effectiveness. However, one main challenge of these services is that the quality of the answers posted by physicians varies over a large spectrum. Physicians may not have sufficient time to answer the questions or just want to post advertisements in the answers. To determine high-quality answers, we can apply classification models on them. However, it is critical to include the corresponding features in the classification models. To further enhance the model performance, we propose a set of novel temporal features based on the characteristics of HQA services. Moreover, we propose a deep learning framework, referred to as a collaborative decision convolutional neural network (CDCNN), to learn the semantic non-linear features embedded in the data. By exploiting the learned non-linear semantic features, we can apply the factorization machines (FM) to obtain the quality score of an answer. Finally, we conduct extensive experiments to show the advantages of the proposed framework. (c) 2017 Elsevier B.V. All rights reserved.\",\n \"Title: Sharpness-preservation video upscaling\\nYear: 2017\\n\\nAbstract: Video upscaling is a common task performing the adaption of the actual video resolution to the screen display area. The extensively used interpolation methods are easily implemented but usually result in some artifacts, such as blurring and aliasing effects. This paper proposes to combine sharpening with interpolation to reduce the blurring effects of enlarged videos, in which videos are firstly preprocessed with sharpening to enhance profiles so as to compensate the loss of high-frequency components during interpolation. To tune sharpness degree in sharpening procedure, the blurriness metric considering image gradients as well as pixel intensities is particularly suggested and the generation rule for sharpening strength is accordingly regulated. In practice, three representative interpolation methods, namely, Bilinear, Bicubic and Lanczos, are experimentally incorporated into our framework to carry out validation. Results with respect to both original and decoded videos show the significant objective and subjective improvements against the respective regular interpolation.\",\n \"Title: Cognitive Gravity Model Based Semi-Supervised Dimension Reduction.\\nYear: 2018\\n\\nAbstract: Dimension reduction is very important for pattern recognition. Preserving the manifold is a popular way to enhance the effect of the dimension reduction method. However, most of the manifold is designed according to the distribution of the data but not the requirement of the classifier, and then the preserved manifold structure could be not what the classifier need. In this paper, we note that the samples are often with different densities, and it is often ignored by many classifiers, such as support vector machine and -nearest neighbors. To overcome this problem, a new manifold based on the cognitive gravity model and Laplace matrix is designed, where the weight of the similar matrix of the Laplace matrix is set by the corresponding gravity. As a result, the difference among the densities of samples can be reduced by preserving the manifold. Subsequently, a new semi-supervised dimension reduction based on the above manifold is designed. The conducted experiments validate the proposed approach in term of the performance of classification.\",\n \"Title: Sparse Stochastic Online AUC Optimization for Imbalanced Streaming Data.\\nYear: 2017\\n\\nAbstract: Area Under the ROC Curve (AUC) is an objective indicator of evaluating classification performance for imbalanced data. In order to deal with large-scale imbalanced streaming data, especially high-dimensional sparse data, this paper proposes a Sparse Stochastic Online AUC Optimization (SSOAO) method. Specifically, we first turn the standard online AUC optimization problem into a stochastic saddle point problem, then optimizing AUC by solving stochastic saddle point problem through AdaGrad optimizer. A sparse regularization term is also added for learning sparse data with high dimension. Comprehensive evaluation has been carried out on the recent benchmark. The experimental results show that the proposed SSOAO has the comparable performance on low-dimensional data, and outperforms other popular AUC optimization methods on high-dimensional sparse imbalanced streaming data. Both time and space complexity for model updating are reduced from O(d(2)) to O(d), which equal to the data dimension.\",\n \"Title: Subsampled Optimization: Statistical Guarantees, Mean Squared Error Approximation, and Sampling Method.\\nYear: 2018\\n\\nAbstract: For optimization on large-scale data, exactly calculating its solution may be computationally difficulty because of the large size of the data. In this paper we consider subsampled optimization for fast approximating the exact solution. In this approach, one gets a surrogate dataset by sampling from the full data, and then obtains an approximate solution by solving the subsampled optimization based on the surrogate. One main theoretical contributions are to provide the asymptotic properties of the approximate solution with respect to the exact solution as statistical guarantees, and to rigorously derive an accurate approximation of the mean squared error (MSE) and an approximately unbiased MSE estimator. These results help us better diagnose the subsampled optimization in the context that a confidence region on the exact solution is provided using the approximate solution. The other consequence of our results is to propose an optimal sampling method, Hessian-based sampling, whose probabilities are proportional to the norms of Newton directions. Numerical experiments with least-squares and logistic regression show promising performance, in line with our results.\",\n \"Title: QuickIM: Efficient, Accurate and Robust Influence Maximization Algorithm on Billion-Scale Networks.\\nYear: 2018\\n\\nAbstract: The Influence Maximization (IM) problem aims at finding k seed vertices in a network, starting from which influence can be spread in the network to the maximum extent. In this paper, we propose QuickIM, the first versatile IM algorithm that attains all the desirable properties of a practically applicable IM algorithm at the same time, namely high time efficiency, good result quality, low memory footprint, and high robustness. On real-world social networks, QuickIM achieves the $Omega(n + m)$ lower bound on time complexity and $Omega(n)$ space complexity, where $n$ and $m$ are the number of vertices and edges in the network, respectively. Our experimental evaluation verifies the superiority of QuickIM. Firstly, QuickIM runs 1-3 orders of magnitude faster than the state-of-the-art IM algorithms. Secondly, except EasyIM, QuickIM requires 1-2 orders of magnitude less memory than the state-of-the-art algorithms. Thirdly, QuickIM always produces as good quality results as the state-of-the-art algorithms. Lastly, the time and the memory performance of QuickIM is independent of influence probabilities. On the largest network used in the experiments that contains more than 3.6 billion edges, QuickIM is able to find hundreds of influential seeds in less than 4 minutes, while all the state-of-the-art algorithms fail to terminate in an hour.\",\n \"Title: Towards Real-Time Service from Remote Sensing: Compression of Earth Observatory Video Data via Long-Term Background Referencing.\\nYear: 2018\\n\\nAbstract: City surveillance enables many innovative applications of smart cities. However, the real-time utilization of remotely sensed surveillance data via unmanned aerial vehicles (UAVs) or video satellites is hindered by the considerable gap between the high data collection rate and the limited transmission bandwidth. High efficiency compression of the data is in high demand. Long-term background redundancy (LBR) (in contrast to local spatial/temporal redundancies in a single video clip) is a new form of redundancy common in Earth observatory video data (EOVD). LBR is induced by the repetition of static landscapes across multiple video clips and becomes significant as the number of video clips shot of the same area increases. Eliminating LBR improves EOVD coding efficiency considerably. First, this study proposes eliminating LBR by creating a long-term background referencing library (LBRL) containing high-definition geographically registered images of an entire area. Then, it analyzes the factors affecting the variations in the image representations of the background. Next, it proposes a method of generating references for encoding current video and develops the encoding and decoding framework for EOVD compression. Experimental results show that encoding UAV video clips with the proposed method saved an average of more than 54% bits using references generated under the same conditions. Bitrate savings reached 25-35% when applied to satellite video data with arbitrarily collected reference images. Applying the proposed coding method to EOVD will facilitate remote surveillance, which can foster the development of online smart city applications.\",\n \"Title: An Asian Face Dataset and How Race Influences Face Recognition.\\nYear: 2018\\n\\nAbstract: The face recognition scheme based on deep learning can give the best face recognition performance at present, but this scheme requires a large amount of labeled face data. The currently available large-scale face datasets are mainly Westerners, only containing few Asians. In practice, we have found that models trained using these data sets are lower in accuracy in identifying Asians than Westerners. Therefore, the establishment of a large-scale Asian face dataset is of great value for the development and deployment of face related applications for Asians. In this paper, we propose a simple semi-automatic approach to collect face images from Internet and build a large-scale Asian face dataset (AFD) containing 2019 subjects and 360,000 images. To the best of our knowledge, this is the largest Asian face image dataset proposed so far. To illustrate the quality of AFD, we train 3 different models with the same CNN structure yet by different training datasets (AFD, WebFace, mixed WebFace& AFD) and verify them on one Western and two Asian face testing datasets. Extensive experimental results show that the model by our AFD outperforms counterparts by a large margin for Asian face recognition. We have made the AFD dataset public to facilitate face recognition development for Asians.\",\n \"Title: Dataset Refinement for Convolutional Neural Networks via Active Learning.\\nYear: 2018\\n\\nAbstract: Convolutional neural networks (CNNs) have shown significant advantages in computer vision fields. For the optimizations of CNNs, most research works focus on feature extraction, which creates deeper structures and better activations, but the optimizations on dataset is rarely discussed. Due to the boom of data, most CNNs suffer from serious problems of dataset redundancy and following high computational burden. To this end, this paper brings in an informativeness ranking thought and proposes a new methodology for dataset refinement based on Active Learning. Extensive experiments prove its effectiveness to achieve a higher classification accuracy for CNNs at a less training cost. Moreover, for classification problems with a large number of class, this paper further proposes Entropy Ranking, a new Active Learning method, to enhance the optimization ability.\",\n \"Title: A Fast Quantum Clustering Approach For Cancer Gene Clustering\\nYear: 2018\\n\\nAbstract: At present, the main problem of gene expression data processing is how to use effective analytical methods to analyze gene expression data to obtain useful information. A large amount of useful information can be obtained by cluster analysis of gene expression data, which provides a basis for biology to predict cell cycle, predict the gene function, discover disease-causing genes and explain some new disease types. In this paper, a fast clustering method is proposed, which effectively combines the advantages of the graph regularized non-negative matrices factorization (GNMF) method with Quantum Clustering (QC) method, effectively improving the running speed of existing clustering methods and improving the clustering accuracy to some extent.\",\n \"Title: Sparse Orthogonal Nonnegative Matrix Factorization For Identifying Differentially Expressed Genes And Clustering Tumor Samples\\nYear: 2018\\n\\nAbstract: Gene expression data are critical for disease diagnoses and classification. However gene expression data usually are high-dimensional and high-noisy. Currently, many matrix factorization methods have been widely used for dimensionality reduction and data preprocessing in bioinformatics. Particularly, nonnegative matrix factorization (NMF) has the outstanding interpretability in analyzing gene expression data due to the nonnegative constraints. In this paper, a new nonnegative matrix factorization algorithm named sparse orthogonal nonnegative matrix factorization (SONMF) is proposed and applied to identify differentially expressed genes and cluster tumor samples, in which the L1-norm regularization and the orthogonal constraint are incorporated into the traditional NMF model to get more powerful data analysis tool. An iterative algorithm is proposed to optimize the new objective function. In order to prove the efficiency of the algorithm, SONMF is tested on four public gene expression datasets and compared with the other four NMF methods. The experimental results on the four real tumor datasets confirm the efficiency of SONMF for identifying differentially expressed genes and clustering tumor samples.\",\n \"Title: A comparative performance analysis of evolutionary algorithms on $${\\\\varvec{k}}$$ k -median and facility location problems.\\nYear: 2018\\n\\nAbstract: k-median and facility location problems are classical NP-hard combinatorial optimization problems. Although there are many experimental studies on them, their theoretical results are relatively few. This paper mainly contributes to investigating the approximation performance of two evolutionary algorithms for the k-median and facility location problems from a theoretical perspective. For k-median problem, we show that the evolutionary algorithms with standard bit mutation (SBM) operator can obtain approximation ratios 5 and \\\\(3{+}2/p\\\\) in expected polynomial time while the evolutionary algorithm with somatic contiguous hypermutation (CHM) operator cannot obtain them. For facility location problem, we show that the evolutionary algorithms with SBM operator can obtain approximation ratio 3 in expected polynomial time while the evolutionary algorithm with CHM operator cannot obtain it. Further, we prove that on a facility location instance the evolutionary algorithm with CHM operator greatly outperforms the evolutionary algorithm with SBM operator.\",\n \"Title: A Wearable Multifunctional Pulse Monitor using Thermosensation-based Flexible Sensors.\\nYear: 2019\\n\\nAbstract: The monitor is small, simple-structured, with multifunction, and thus provides a promising auxiliary approach for traditional Chinese medicine (TCM) pulse diagnosis.\",\n \"Title: Integrative graph regularized matrix factorization for drug-pathway associations analysis.\\nYear: 2019\\n\\nAbstract: We propose a novel drug-pathway association identification method: Integrative Graph regularized Matrix Factorization (IGMF). It employs graph regularization to encode data geometrical information and prevent possible overfitting in prediction. Furthermore, it achieves parts-based and sparse data representation by imposing L1-norm regularization on the objective function. Empirical studies demonstrate that IGMF has strong advantages in identifying more new drug-pathway associations compared to its peer methods. It further shows a good capability to unveil the intrinsic structures of data. As an effective drug-pathway discovery method, it will inspire new analytics methods in this subfield.\",\n \"Title: A Proportional Odds Model Of Human Mobility And Migration Patterns\\nYear: 2019\\n\\nAbstract: The modelling of human mobility and migration patterns has received much attention due to its substantial importance. Despite long-term efforts, we still lack a modelling framework that captures mobility patterns and further obtains a prospective view of movement trends with regards to diverse impacting factors. Here, we propose a proportional odds model of human mobility and migration (POM-HM) that takes a probabilistic approach to model human movements. Our model is based on the migration probability with a log-logistic distribution under the proportional odds assumption. Explanatory variables are introduced into the model by re-parameterizing the probability distribution function. The two resultant functions, namely, the migration strength and cumulative hazard, are used to estimate regional differences among travel fluxes and their tendencies. The performance of the POM-HM in terms of its validity and accuracy is examined and compared with the gravity model and the radiation model. The probability-based modelling framework enables us to investigate regional variations in migrant fluxes consequently further predict potential future patterns. In short, our modelling approach captures the probabilistic nature of human mobility and migration and furthers our understanding of both the spatiotemporal patterns of population movements and the impacts of various driving forces.\",\n \"Title: Fast Rectangle Counting on Massive Networks\\nYear: 2018\\n\\nAbstract: Rectangle has been recognized as an essential motif in a large number of real-world networks. Counting rectangles in a network plays an important role in network analysis. This paper comprehensively studies the rectangle counting problem on large networks. We propose a novel counting paradigm called the wedge-centric counting, where a wedge is a simple path consisting of three vertices. Unlike the traditional edge-centric counting, the wedge-centric counting uses wedges instead of edges as building blocks of rectangles. The main advantage of the wedge-centric counting is that it does not need to access two-hop neighbors. Based on this paradigm, we develop a collection of rectangle counting algorithms, including an in-memory algorithm with lower time complexity, an external-memory algorithm with the optimal I/O complexity, and two randomized algorithms with provable error bounds. The experimental results on a variety of real networks verify the effectiveness and the efficiency of the proposed wedge-centric rectangle counting algorithms.\",\n \"Title: Dimensionality Reduction Via Adjusting Data Distribution Density\\nYear: 2018\\n\\nAbstract: Dimensionality reduction is an important processing step for pattern recognition. Designing a new optimization goal is a popular method to improve the effect of the dimensionality decrease method. In this paper, we noted that the distribution density of data was not considered in the most classifiers, which may have a negative impact on the classifier. To overcome the above problem, a new optimization goal is designed under the distribution density of the data. In this optimization goal, the sample with smaller density owns larger impact for the optimization result, and then the density of sample could be adjusted to nearly the same in the low dimensional space. The experiments performed verified the proposed method in terms of classification performance.\",\n \"Title: Image Artistic Style Migration Based On Convolutional Neural Network\\nYear: 2018\\n\\nAbstract: In recent years, the wave of artificial intelligence technology, which is guided by deep learning, is becoming more and more widely applied to all fields of society. Among them, the cross collision between artificial intelligence and art has attracted great attention in related research fields. The migration of image artistic style based on deep learning has become one of the active research topics. In this paper, a simple and effective method is presented for image artistic style migration. That is, firstly, we specify an input image as an original image (it is also called a content image); at the same time, another or more images are designated as the desired image style. And then, by constructing the network model based on convolutional neural network (CNN), the image style can be transformed while the content information of the content image is guaranteed, so that the final output image shows the perfect combination of the content of the input image and the style of the style image. The core of the proposed artistic style migration strategy is the construction of an unified CNN framework. Here, a generation network is set up based on a deep residual network and the VGG-19 network model is applied to built a loss network. The experimental results on an application system show that our proposed method achieves a good synthesis effect for image artistic style migration.\",\n \"Title: Air Quality Index Forecasting Based On Svm And Moments\\nYear: 2018\\n\\nAbstract: A novel air quality index (AQI) forecasting method based on support vector machine (SVM) and moments is proposed in this paper. By using it, the AQI value of a sky image can be forecasted. In order to improve the forecasting accuracy and stability, color moments, color correlogram and wavelet features are used to extract the image features, which transfers the input image from color space to feature space. We train the SVM with the input of these extracted features. Then the trained SVM is utilized to achieve the AQI forecasting for new images. The experimental results improve that the proposed method has good AQI forecasting results, and the accuracy of the testing dataset is more than 82.3%, with 1300 training images and 200 test images.\",\n \"Title: Truss decomposition of uncertain graphs.\\nYear: 2017\\n\\nAbstract: The k-truss of a graph is the largest edge-induced subgraph such that every edge is contained in at least k triangles within the subgraph, where a triangle is a cycle consisting of three vertices. As a new notion of cohesive subgraphs, truss has recently attracted a lot of research attentions in the database and data mining fields. At the same time, uncertainty is an intrinsic property of massive graph data, and truss decomposition (i.e., finding all k-trusses of a graph) has become a key primitive on uncertain graphs. In this paper, we study the truss decomposition problem on uncertain graphs, that is, finding all highly probable k-trusses of an uncertain graph. We first give an formal statement of the truss decomposition problem on uncertain graphs. Then, we prove that the truss decomposition of an uncertain graph attains two elegant properties, namely uniqueness and hierarchy. We show that the truss decomposition of an uncertain graph can be found in $$O(m^{1.5}Q)$$O(m1.5Q) time by proposing an in-memory algorithm called $$\\\\\\\\mathtt {TD_{mem}}$$TDmem, where m is the number of edges of the uncertain graph, and Q is at most the maximum number of common neighbors of the endpoints of an edge. When an uncertain graph is too large to fit into main memory, we propose an external-memory algorithm $$\\\\\\\\mathtt {TD_{I/O}}$$TDI/O to find the truss decomposition of the uncertain graph. Extensive experiments have been carried out to evaluate the practical performance of the proposed algorithms. The experimental results verify that both $$\\\\\\\\mathtt {TD_{mem}}$$TDmem and $$\\\\\\\\mathtt {TD_{I/O}}$$TDI/O are efficient when an uncertain graph is small enough to fit into main memory, and that $$\\\\\\\\mathtt {TD_{I/O}}$$TDI/O is much faster than $$\\\\\\\\mathtt {TD_{mem}}$$TDmem when the graph is too large to fit into main memory.\",\n \"Title: Quarter-Century Offshore Winds from SSM/I and WRF in the North Sea and South China Sea.\\nYear: 2016\\n\\nAbstract: We study the wind climate and its long-term variability in the North Sea and South China Sea, areas relevant for offshore wind energy development, using satellite-based wind data, because very few reliable long-term in-situ sea surface wind observations are available. The Special Sensor Microwave Imager (SSM/I) ocean winds extrapolated from 10 m to 100 m using the Charnock relationship and the logarithmic profile method are compared to Weather Research and Forecasting (WRF) model results in both seas and to in-situ observations in the North Sea. The mean wind speed from SSM/I and WRF differ only by 0.1 m/s at Fino1 in the North Sea, while west of Hainan in the South China Sea the difference is 1.0 m/s. Linear regression between SSM/I and WRF winds at 100 m show correlation coefficients squared of 0.75 and 0.67, standard deviation of 1.67 m/s and 1.41 m/s, and mean difference of -0.12 m/s and 0.83 m/s for Fino1 and Hainan, respectively. The WRF-derived winds overestimate the values in the South China Sea. The inter-annual wind speed variability is estimated as 4.6% and 4.4% based on SSM/I at Fino1 and Hainan, respectively. We find significant changes in the seasonal wind pattern at Fino1 with springtime winds arriving one month earlier from 1988 to 2013 and higher winds in June; no yearly trend in wind speed is observed in the two seas.\",\n \"Title: Research on concurrency comparison modeling based on $$\\\\uppi $$ calculus in future computer technology\\nYear: 2019\\n\\nAbstract: \\\\(\\\\uppi \\\\) calculus is an effective tool targeted at the description and modeling of mobile concurrency systems. In this paper, a brief introduction of \\\\(\\\\uppi \\\\) calculus is followed with the discussion on the \\\\(\\\\uppi \\\\)-calculus-based description and modeling of the comparison operation, one of the basic computer operations. According to the two different ways of data storage: the indexed storage and linked-list storage of elements, the paper analyzes the \\\\(\\\\uppi \\\\)-calculus-based formalized description method in the comparison of any two elements. Moreover, a theoretical efficiency analysis is performed on the comparison algorithm of relatively complex linked-list storage of elements in this paper.\",\n \"Title: Factorization machines and deep views-based co-training for improving answer quality prediction in online health expert question-answering services.\\nYear: 2018\\n\\nAbstract: •Automatically exploit unlabeled answers to improve the learning performance without the need for expensive expert annotation.•Present a solution to train a good deep co-training framework on sparse short texts.•Introduce two unique deep textual views based on domain-specific word embeddings.•Propose a deep co-training framework to learn the hidden semantic embedding.\",\n \"Title: AliGraph: A Comprehensive Graph Neural Network Platform.\\nYear: 2019\\n\\nAbstract: An increasing number of machine learning tasks require dealing with large graph datasets, which capture rich and complex relationship among potentially billions of elements. Graph Neural Network (GNN) becomes an effective way to address the graph learning problem by converting the graph data into a low dimensional space while keeping both the structural and property information to the maximum extent and constructing a neural network for training and referencing. However, it is challenging to provide an efficient graph storage and computation capabilities to facilitate GNN training and enable development of new GNN algorithms. In this paper, we present a comprehensive graph neural network system, namely AliGraph, which consists of distributed graph storage, optimized sampling operators and runtime to efficiently support not only existing popular GNNs but also a series of in-house developed ones for different scenarios. The system is currently deployed at Alibaba to support a variety of business scenarios, including product recommendation and personalized search at Alibabau0027s E-Commerce platform. By conducting extensive experiments on a real-world dataset with 492.90 million vertices, 6.82 billion edges and rich attributes, AliGraph performs an order of magnitude faster in terms of graph building (5 minutes vs hours reported from the state-of-the-art PowerGraph platform). At training, AliGraph runs 40%-50% faster with the novel caching strategy and demonstrates around 12 times speed up with the improved runtime. In addition, our in-house developed GNN models all showcase their statistically significant superiorities in terms of both effectiveness and efficiency (e.g., 4.12%-17.19% lift by F1 scores).\",\n \"Title: A Wearable Human Motion Tracking Device Using Micro Flow Sensor Incorporating with Micro Accelerometer.\\nYear: 2020\\n\\nAbstract: Objective: This paper proposes a wearable human motion tracking device using micro flow sensor incorporating a micro accelerometer, which allows detecting postures of human limbs in dynamic motions. Methods: A micro flow sensor is used to detect motion velocity, from which, motion acceleration can be estimated. Thereby, the limb postures are figured out by using the components of the gravity accel...\",\n \"Title: Motion Velocity, Acceleration and Energy Expenditure Estimation Using Micro Flow Sensor.\\nYear: 2019\\n\\nAbstract: Motion velocity, acceleration, and energy expenditure estimations are important in quantitative assessments for physical recovery and exercise-based interventions for post-stroke patients with partial losses of neurological functions. This paper proposes a novel wearable motion estimation device using a micro flow sensor, which realizes motion velocity, acceleration detection, and energy expenditure estimation for human limb motion. A homemade micro thermal flow sensor is used to detect motion velocity. Jerk-Kalman based algorithm is proposed to extract motion acceleration from the flow sensor outputs. Motion velocity and acceleration are used to estimate energy expenditure of limb motion. Calibration experiments and application cases are conducted to validate the effectiveness of the methodology. The micro flow sensor based motion estimation method is free of accumulated error, robust for dynamic motion measurement, and provides a promising auxiliary approach for evaluating energy expenditures of human limbs in rehabilitation training.\",\n \"Title: Constrained Truth Discovery\\nYear: 2022\\n\\nAbstract: To aggregate useful information among diversified sources, a hotspot research topic called truth discovery has emerged in recent years. Existing truth discovery methods attempt to infer the true attribute values for the entities by identifying and trusting reliable data sources. That is, the values provided by reliable sources are more likely to be the true values. However, all these methods negle...\",\n \"Title: Random Effect Bandits\\nYear: 2022\\n\\nAbstract: This paper studies regret minimization in a multi-armed bandit. It is well known that side information, such as the prior distribution of arm means in Thompson sampling, can improve the statistical efficiency of the bandit algorithm. While the prior is a blessing when correctly specified, it is a curse when misspecified. To address this issue, we introduce the assumption of a random-effect model to bandits. In this model, the mean arm rewards are drawn independently from an unknown distribution, which we estimate. We derive a random-effect estimator of the arm means, analyze its uncertainty, and design a UCB algorithm ReUCB that uses it. We analyze ReUCB and derive an upper bound on its n-round Bayes regret, which improves upon not using the random-effect structure. Our experiments show that ReUCB can outperform Thompson sampling, without knowing the prior distribution of arm means.\",\n \"Title: GraphScope: a unified engine for big graph processing\\nYear: 2021\\n\\nAbstract: AbstractGraphScope is a system and a set of language extensions that enable a new programming interface for large-scale distributed graph computing. It generalizes previous graph processing frameworks (e.g., Pregel, GraphX) and distributed graph databases (e.g., Janus-Graph, Neptune) in two important ways: by exposing a unified programming interface to a wide variety of graph computations such as graph traversal, pattern matching, iterative algorithms and graph neural networks within a high-level programming language; and by supporting the seamless integration of a highly optimized graph engine in a general purpose data-parallel computing system.A GraphScope program is a sequential program composed of declarative data-parallel operators, and can be written using standard Python development tools. The system automatically handles the parallelization and distributed execution of programs on a cluster of machines. It outperforms current state-of-the-art systems by enabling a separate optimization (or family of optimizations) for each graph operation in one carefully designed coherent framework. We describe the design and implementation of GraphScope and evaluate system performance using several real-world applications.\",\n \"Title: Cardinality Estimation in DBMS: A Comprehensive Benchmark Evaluation.\\nYear: 2022\\n\\nAbstract: Cardinality estimation (CardEst) plays a significant role in generating high-quality query plans for a query optimizer in DBMS. In the last decade, an increasing number of advanced CardEst methods (especially ML-based) have been proposed with outstanding estimation accuracy and inference latency. However, there exists no study that systematically evaluates the quality of these methods and answer the fundamental problem: to what extent can these methods improve the performance of query optimizer in real-world settings, which is the ultimate goal of a CardEst method. In this paper, we comprehensively and systematically compare the effectiveness of CardEst methods in a real DBMS. We establish a new benchmark for CardEst, which contains a new complex realworld dataset STATS and a diverse query workload STATS-CEB. We integrate multiple most representative CardEst methods into an open-source database system PostgreSQL, and comprehensively evaluate their true effectiveness in improving query plan quality, and other important aspects affecting their applicability, ranging from inference latency, model size, and training time, to update efficiency and accuracy. We obtain a number of key findings for the CardEst methods, under different data and query settings. Furthermore, we find that the widely used estimation accuracy metric(Q-Error) cannot distinguish the importance of different sub-plan queries during query optimization and thus cannot truly reflect the query plan quality generated by CardEst methods. Therefore, we propose a new metric P-Error to evaluate the performance of CardEst methods, which overcomes the limitation of Q-Error and is able to reflect the overall end-to-end performance of CardEst methods. We have made all of the benchmark data and evaluation code publicly available at https://github.com/Nathaniel-Han/Endto-End-CardEst-Benchmark.\",\n \"Title: Deep Bandits Show-Off: Simple and Efficient Exploration with Deep Networks.\\nYear: 2021\\n\\nAbstract: Designing efficient exploration is central to Reinforcement Learning due to the fundamental problem posed by the exploration-exploitation dilemma. Bayesian exploration strategies like Thompson Sampling resolve this trade-off in a principled way by modeling and updating the distribution of the parameters of the action-value function, the outcome model of the environment.However, this technique becomes infeasible for complex environments due to the computational intractability of maintaining probability distributions over parameters of outcome models of corresponding complexity.Moreover, the approximation techniques introduced to mitigate this issue typically result in poor exploration-exploitation trade-offs, as observed in the case of deep neural network models with approximate posterior methods that have been shown to underperform in the deep bandit scenario.In this paper we introduce Sample Average Uncertainty (SAU), a simple and efficient uncertainty measure for contextual bandits.While Bayesian approaches like Thompson Sampling estimate outcomes uncertainty indirectly by first quantifying the variability over the parameters of the outcome model, SAU is a frequentist approach that directly estimates the uncertainty of the outcomes based on the value predictions.Importantly, we show theoretically that the uncertainty measure estimated by SAU asymptotically matches the uncertainty provided by Thompson Sampling, as well as its regret bounds.Because of its simplicity SAU can be seamlessly applied to deep contextual bandits as a very scalable drop-in replacement for epsilon-greedy exploration.We confirm empirically our theory by showing that SAU-based exploration outperforms current state-of-the-art deep Bayesian bandit methods on several real-world datasets at modest computation cost, and make the code to reproduce our results available at \\\\url{https://github.com/ibm/sau-explore}.\",\n \"Title: Predicting miRNA-disease associations via layer attention graph convolutional network model\\nYear: 2022\\n\\nAbstract: MiRNA is a class of non-coding single-stranded RNA molecules with a length of approximately 22 nucleotides encoded by endogenous genes, which can regulate the expression of other genes. Therefore, it is very important to predict the associations between miRNA and disease. Predecessors developed a new prediction method of drug-disease association, and it achieved good results. In this paper, we introduced the method of LAGCN to identify potential miRNA-disease associations. First, we integrate three associations into a heterogeneous network, such as the known miRNA-disease association, miRNA-miRNA similarities and disease-disease similarities, next we apply graph convolution network to learn the embedding of miRNA and disease. We use an attention mechanism to combine embedding from multiple convolution layers. Unobserved miRNA-disease associations are scored based on integrated embedding. After fivefold cross-validations, the value of AUC is reached 0.9091, which is higher than other prediction methods and baseline methods. In this paper, we introduced the method of LAGCN to identify potential miRNA-disease associations. LAGCN has achieved good performance in predicting miRNA-disease associations, and it is superior to other association prediction methods and baseline methods.\",\n \"Title: Towards Energy-Efficient CGRAs via Stochastic Computing\\nYear: 2022\\n\\nAbstract: Stochastic computing (SC) is a promising computing paradigm for low-power and low-cost applications with the added benefit of high error tolerance. Meanwhile, Coarse-Grained Re-configurable Architecture (CGRA) is also a promising platform for domain-specific applications for its combination of energy efficiency and flexibility. Intuitively, introducing SC to CGRA would synergistically reinforce the strengths of both paradigms. Accordingly, this paper proposes an SC-based CGRA by replacing the exact multiplication in traditional CGRA with an SC-based multiplication, where the problem of accuracy and latency are both improved using parallel stochastic sequence generators and leading zero shifters. In addition, with the flexible connections among PEs, the high-accuracy operation can be easily achieved by combing neighbor PEs without switching costs like power-gating. Compared to the state-of-the-art approximate computing design of CGRA, our proposed CGRA has 16% more energy reduction and 34% energy efficiency improvement while keeping high configuration flexibility.\",\n \"Title: RF-CGRA: A Routing-Friendly CGRA with Hierarchical Register Chains\\nYear: 2022\\n\\nAbstract: CGRAs are promising architectures to accelerate domain-specific applications as they combine high energy-efficiency and flexibility. With either isolated register files (RFs) or link-consuming distributed registers in each processing element (PE), existing CGRAs are all not friendly to data routing for data-flow graphs (DFGs) with a high edge/node ratio since there are many multi-cycle dependences. To this end, this paper proposes a Routing-Friendly CGRA (RF-CGRA) where hierarchical (intra-PE or inter-PE) register chains could be flexibly (wide range of chain length) and compactly (consuming fewer links among PEs) achieved for data routing, resulting in a new mapping problem that requires the improvement of a compiler. Experimental results show that RF-CGRA gets 1.19× performance and 1.14× energy efficiency of the state-of-the-art CGRA with single-cycle multi-hop connections (HyCUBE) while keeping a moderate compilation time.\",\n \"Title: Degradation analysis with nonlinear exponential-dispersion process: Bayesian offline and online perspectives\\nYear: 2022\\n\\nAbstract: Exponential-dispersion (ED) process has been recently introduced and demonstrated as a promising degradation model, which can include classical Wiener, gamma, and inverse Gaussian (IG) processes as special cases. However, most related studies are based on offline and point estimation methods, which limit their capability for uncertainty quantification and online update inference. In this paper, nonlinear ED process models equipped with Bayesian offline and online inference methods are presented. Tweedie ED process models are studied for degradation analysis with accelerated factors and unit-to-unit variability. Bayesian offline method based on NO-U-Turn sampler (NUTS) algorithm and Bayesian online method based on particle filter are developed, respectively. The offline method is presented to enhance the ED process based degradation analysis with uncertainty quantification. The online method is developed for the applications with limited storage and computing resources, for which degradation observations are analyzed on-the-fly with improved efficiency. Effectiveness and characteristics of the proposed methods are demonstrated through a simulation study and two case studies.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":82,"string":"82"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":55,"string":"55"}}},{"rowIdx":56,"cells":{"question_id":{"kind":"string","value":"Makoto Takizawa"},"question":{"kind":"string","value":"Generate an abstract for the title \"A walkthrough from smart spaces to smart hyperspaces towards a smart world with ubiquitous intelligence\" using the following items: 1. Ubiquitous Computing\n2. Smart u-things\n3. Smart World\n4. Smart Objects\n5. Smart Hyperspace"},"answer":{"kind":"string","value":"In the ubicomp/percomp era, more ubiquitous computation/information/service would be the main driving force, and the corresponding essential element would be the various smart/intelligent ubiquitous things or u-things with attached/embedded/blended computers. Based on the soon available ubiquitous networking infrastructures and services, such ordinary u-things surrounding us are capable of computing, communicating, connecting or being connected, and behaving smartly with some intelligence. Our world would evolve towards a smart world mainly characterized by ubiquitous intelligence and filled with these smart u-things falling into three categories; smart object, smart space and smart system. The next research phase to emerge, we believe, is to coordinate these diverse smart objects and integrate these isolated smart spaces together into a higher level of spaces known as smart hyperspace or hyper-environments, and eventually create the smart world. In this paper, we discuss the potential trends and related challenges from smart things, smart spaces to smart hyperspaces toward the smart world with ubiquitous intelligence."},"correct_answer":{"kind":"string","value":"In the ubicomp/percomp era, more ubiquitous computation/information/service would be the main driving force, and the corresponding essential element would be the various smart/intelligent ubiquitous things or u-things with attached/embedded/blended computers. Based on the soon available ubiquitous networking infrastructures and services, such ordinary u-things surrounding us are capable of computing, communicating, connecting or being connected, and behaving smartly with some intelligence. Our world would evolve towards a smart world mainly characterized by ubiquitous intelligence and filled with these smart u-things falling into three categories; smart object, smart space and smart system. The next research phase to emerge, we believe, is to coordinate these diverse smart objects and integrate these isolated smart spaces together into a higher level of spaces known as smart hyperspace or hyper-environments, and eventually create the smart world. In this paper, we discuss the potential trends and related challenges from smart things, smart spaces to smart hyperspaces toward the smart world with ubiquitous intelligence."},"documents":{"kind":"list like","value":["Title: Experimental Results of a Raspberry Pi Based WMN Testbed for Different OSs in Indoor Environment Considering LoS Scenario.\nYear: 2015\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using Raspbian and OpenWRT OSs. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario. For evaluation we considered throughput, Packet Delivery Ratio (PDR), delay, jitter and hop count metrics. The experimental results show that the testbed mounted in OpenWRT has better results than Raspbian.","Title: Energy-Aware Migration and Replication of Processes in a Cluster\nYear: 2015\n\nAbstract: Application processes have to be efficiently performed in presence of server faults in a cluster. Replicas of a process are performed on multiple servers to be tolerant of server faults. However, the more number of replicas of a process are performed, the more reliably and available the process can be performed but the more amount of electric energy is consumed by servers. In this paper, we take a process migration approach to reliably and energy-efficiently performing process replicas. A process is replicated to multiple replicas. Each replica is performed on a server different from the other replicas to realize fault-tolerant computation. In addition, each replica of process migrates from a current server to another server if the current server is expected to consume the more electric energy. Thus, replicas migrate to servers to reduce the total electric energy consumption of the cluster.","Title: Power Consumption and Computation Models of a Storage Server.\nYear: 2015\n\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems including a huge number of servers like cluster computing systems. Types of application processes like computation, storage, and communication processes are performed on servers in clusters. In clusters, most applications use not only CPU resources but also storage drives like database and web applications. In this paper, we consider storage processes which read and write files in storage devices. The SPCS model (simple power consumption model for a storage server) shows how much electric power a server consumes to perform storage and computation processes. In our macro-level approach, we first measure the electric power consumed by a whole server to perform storage and computation processes and the computation time of each process. Then, we define the SPCS model of a server to perform storage and computation processes by abstracting parameters like number of processes which dominate the electric power consumption. We also define a simple computation model for a storage server (SPCS model) to perform storage and computation processes.","Title: Role Safety in a Flexible Read-Write Abortion Protocol.\nYear: 2015\n\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally reads an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the flexible read-write-abortion with role sensitivity (FRWA-R) and object sensitivity (FRWA-O) protocols are discussed to prevent illegal information flow. Here, a transaction is aborted with some probability once illegally reading an object. The abortion probability depends on the sensitivity of roles which the transaction holds and objects which the transaction illegally reads. The role sensitivity and object sensitivity show how many transactions which hold the role and illegally read the object are aborted after illegally reading the object, respectively. Here, the sensitivity just monotonically increases each time a transaction is aborted. In this paper, we newly propose a safety concept of a role and an FRWA with role safety (FRWA-RS) protocol where the safety of a role increases and decreases if a transaction holding the role and illegally reading objects commits and aborts, respectively. A transaction with safer roles is aborted with smaller probability. In the evaluation, we show a fewer number of transactions are aborted in the FRWA-RS protocol than the RWA protocol while more than the WA protocol and transactions are more efficiently performed than the WA protocol.","Title: Reliable and Efficient Parallel Transmission Protocols in P2P Networks.\nYear: 2015\n\nAbstract: In infrastructureless networks like P2P networks and mobile ad hoc networks, a pair of nodes are not always supported with reliable and efficient communication. For example, some relay nodes may be faulty and a communication link between some pair of neighboring nodes may be degraded in QoS due to noise. In this paper, we propose a parallel transmission protocol for reliably and efficiently transmitting data in P2P overlay networks. Packets of data are transmitted in multiple communication paths to support enough QoS. Even if each communication path does not support applications wit enough QoS, amount of QoS supported by multiple communication paths can support enough QoS. A subsequence of packets are in addition replicated with a parity packet in order to be tolerant of packet loss. Even if a packet is lost, the lost packet can be recovered by the parity packet and the other packets in the subsequence. Packets are lost in a burst manner. In order to be tolerant of burst loss of packets in a communication path, we discuss vertical and horizontal parity packets. We discuss how packets of data are allocated to multiple communication paths in order to increase the throughput and are replicated to be tolerant of burst packet loss.","Title: Energy-Efficient Virtualisation of Threads in a Server Cluster.\nYear: 2015\n\nAbstract: It is critical to reduce the electric power consumed by servers in a cluster in order to realize eco society. In our previous studies, the multi-level power consumption (MLPC) model of a server with a multi-thread CPU, the power consumption of the server is proposed and the globally energy-aware (GEA) algorithm is discussed to select a server for each process in a cluster. Here, not only the total electric energy consumption of all the servers but also the ratio of the basic electric energy consumed by the servers to the total electric energy consumption can be reduced in a cluster. However, the GEA algorithm is not scalable since every server is checked to find a server for each process in a cluster. In this paper, we newly propose a scalable energy-aware (SEA) algorithm to select a server for a process. Here, some number of servers are first randomly selected in a cluster and one server is then selected in the selected servers by the GEA algorithm. We evaluate the SEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the SEA algorithm compared with other algorithms.","Title: Evaluation of Energy-Aware Server Selection Algorithms\nYear: 2015\n\nAbstract: The electric power consumed by servers has to be reduced in a cluster in order to realize eco society. We take a macro level approach to reducing the total electric energy consumption of servers to perform application processes in a server cluster. Servers are now equipped with multi-core CPUs. In this paper, we discuss a multi-level power consumption (MLPC) model of a server with a multi-core CPU. Here, the power consumption of a server depends on the number of active cores and active threads where at least one application process is performed. We also discuss a multi-level computation (MLC) model which gives the expected execution time of a process which is concurrently performed with other processes on a server with a multi-core CPU. Based on the MLPC model and the MLC model, we discuss an energy-aware (EA) algorithm to select a server for each process requested by a client in a cluster so as to reduce the total electric energy consumption while satisfying deadline requirements of the processes. We evaluate the EA algorithm and show not only the total energy consumption but also the average execution time of each process is reduced in the EA algorithm compared with the round-robin (RR) and random (RD) algorithms.","Title: Energy-Efficient Replication and Migration of Processes in a Cluster\nYear: 2015\n\nAbstract: Application processes have to be efficiently performed in presence of server faults in a cluster. Multiple replicas of a process are performed on multiple servers. However, the more number of replicas of a process are performed, the more reliable and available the process can be performed but the more amount of electric energy is consumed. In this paper, we take a process migration (MG) approach to energy efficiently and reliably performing multiple replicas of an application process on servers. A replica of a process performed on a current server st migrates to another server su if the server su is expected to consume a smaller amount of electric energy to perform the replica than the current server st while the deadline constraint of the process is satisfied. We consider synchronous and asynchronous ways for process replicas to migrate to servers. In the synchronous migration, every replica migrates to another server on a same computation state. In the asynchronous migration, each replica makes a decision on when the replica migrates to which server.","Title: Power Consumption and Computation Models of Virtual Machines to Perform Computation Type Application Processes\nYear: 2015\n\nAbstract: Scalable and fault-tolerant information systems like cloud systems are realized in server cluster systems. Server cluster systems are equipped with virtual machines to provide applications with scalable and fault-tolerant services. Scalable and fault-tolerant application services can be provided by balancing processing load among virtual machines to perform application processes. On the other hand, a large amount of electric energy is consumed in a server cluster system since multiple virtual machines are performed on multiple servers which consume electric energy to perform application processes. In order to design and implement an energy-aware server cluster system, the computation model and power consumption model of a server to perform application processes on multiple virtual machines have to be defined. In this paper, we first define the computation model of a virtual machine to perform application processes. We also define the power consumption model of a server to perform application processes on virtual machines.","Title: A Flexible Read-Write Abortion Protocol with Sensitivity of Objects to Prevent Illegal Information Flow\nYear: 2015\n\nAbstract: In information systems, objects have to be not only legally accessed in presence of illegal accesses but also data in a suspicious object is not allowed to flow to another object. A transaction illegally and suspiciously reads an object if the transaction reads the object which includes data in other objects which are not allowed to be read and the object which is suspicious, respectively. A transaction illegally and impossibly writes an object after illegally and suspiciously reading an object, respectively. The write-abortion (WA), read-write-abortion (RWA), and flexible RWA (FRWA) protocols to prevent illegal information flow are proposed in our previous papers. In the WA and RWA protocols, a transaction is aborted once issuing an illegal or impossible write and issuing an illegal read or impossible write, respectively. Reads are meaninglessly performed since the reads are later undone due to the abortion of the transaction in the WA protocol. Reads which can be performed after an illegal read are not performed, i.e. Lost since a transaction is aborted just once issuing an illegal read in the RWA protocol. In the FRWA protocol, a transaction is aborted with some probability once illegally reading an object in order to reduce the number of meaningless and lost reads. We newly introduce the sensitivity concept of an object in order to decide on the abortion probability. The more number of transactions are aborted after illegally reading an object, the more highly sensitive the object is. A transaction which illegally reads a more sensitive object is aborted with higher probability. In the evaluation, we show the execution time of each transaction in the FRWA protocol is shorter than WA and more number of reads can be performed than RWA.","Title: Concurrency Control Based on Subject and Purpose Concepts\nYear: 2007\n\nAbstract: A subject doing a job function plays a role in an enterprise. In the role-based access control model, a role is a set of access rights. A subject granted a role can issue an access request in the role. In addition, objects are required to be consistent even if multiple transactions concurrently manipulate an object in a conflicting way. Here, a subject playing more significant roles should take the object prior to another subject. First, we discuss which roles are more significant than other roles in terms of types of methods. Next, we define which subject is moresignificant in terms of significancy of roles and authorization relations. A method issued by a more significant subject should be performed before another conflicting method issued by a less significant subject in the subject-oriented (SO) view. A transaction issued by a subject is associated with a subset of roles granted to the subject, which is named purpose. A method with a more significant purpose should be performed before another method with a less significant purpose in the purpose-oriented (PO) view. In this paper, we discuss how conflicting methods are ordered in a unique SO and PO (SPO) view. We discuss an SPO scheduler where multiple conflicting transactions are serializable in the SPO view. We evaluate the SPO scheduler compared with the traditional two-phase locking protocol in terms of throughput.","Title: A GA-Based Simulation System for WMNs: Performance Analysis of WMN-GA System for Different WMN Architectures Considering DCF and EDCA\nYear: 2015\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In our previous work, we evaluated WMN-GA system which is based on Genetic Algorithms (GAs) to find an optimal location assignment for mesh routers. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance for Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for normal distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the throughput of I/B WMN is higher than Hybrid WMN architecture. The delay and jitter of Hybrid WMN is a lower compared with I/B WMN. The fairness index of 10 and 20 flows is higher than 30 flows for both architectures. In I/B architecture the fairness index of DCF is higher than EDCA. However, for Hybrid WMN, the fairness index of EDCA is higher than DCF.","Title: An Energy-Efficient Load Balancing Algorithm to Perform Computation Type Application Processes for Virtual Machine Environments.\nYear: 2015\n\nAbstract: There are various types of high performance, scalable, and fault-tolerant information systems like cloud systems to realize applications on distributed systems. Virtual machines are used to realize these distributed applications in server cluster systems. In order to satisfy application requirements like deadline constraint for each application process, processing load of virtual machines has to balance with one another in a server cluster system. Here, in addition to achieving the performance objectives, the total electric energy consumption of a server cluster system to perform application processes has to be reduced as discussed in Green computing since a server cluster system is composed of large number of servers and consumes a large amount of electric energy to perform application processes. In our previous studies, the power consumption model of a server to perform application processes on virtual machines which migrate on servers is proposed. In addition, the computation model of a virtual machine to perform computation type application processes is proposed. In this paper, we propose the energy consumption laxity based (ECLB) algorithm to allocate computation type application processes to virtual machines in a server cluster based on the proposed computation model and power consumption model so that the total energy consumption of a server cluster and computation time of each process can be reduced. We evaluate the ECLB algorithm in terms of the total energy consumption of a server cluster and computation time of each process compared with basic round-robin (RR) algorithm. Evaluation results show the average total energy consumption of a server cluster and average computation time of each process in the ECLB algorithm can be maximumly reduced to 1.9% and 12.6% of the RR algorithm, respectively.","Title: Reduction of Unnecessarily Ordered Messages in Scalable Group Communication.\nYear: 2015\n\nAbstract: In distributed applications, multiple processes are cooperating with one another by exchanging messages in networks. Information systems like cloud computing systems are getting scalable, which are composed of a huge number of processes. In group communications, messages sent by processes have to be causally delivered to every process in a group. The vector clock is widely used in group communication protocols but cannot be adopted to scalable groups due to communication and computation overheads. In the linear clock, the message length is O(1) but some pairs of messages are unnecessarily ordered even if the messages are not required to be causally delivered. In this paper, we discuss a communication protocol for a scalable group where linear clock and physical clock are used to reduce the number of pairs of messages unnecessarily ordered. We consider a group of multiple processes where the maximum offset of every physical clock is the same, i.e. homogeneous clock but maximum delay time between every pair of processes is not the same, i.e. heterogeneous network. We evaluate the protocol and show the number of pairs of unnecessarily ordered messages can be reduced compared with the linear clock protocol.","Title: Eco Models of Storage-Based Severs.\nYear: 2015\n\nAbstract: Information systems are getting scalable like cloud computing systems and Internet of Things (IoT). It is critical to reduce electric energy consumed in our society. In information systems, we have to reduce the electric energy consumed by computers, especially servers in clusters to perform application processes. Types of application processes like computation, storage, and communication processes are performed on servers in clusters. Computation processes consume CPU resource to do the computation like scientific computation. The power consumption models like simple power consumption (SPC) and multi-level power consumption (MLPC) models are already proposed for computation processes in our previous studies. In this paper, we consider storage processes which read and write files in storage devices. We newly propose a simple power consumption model for a storage of a server (SPCS model), which shows how much electric power the server consumes to perform storage and computation processes. In our macro-level approach, we first measure the electric power consumed by a whole server to perform storage and computation processes. Then, we define the SPCS model of a server to perform storage and computation processes by abstracting parameters like number of processes which dominate the electric power consumption.","Title: On Streaming Consistency of Big Data Stream Processing in Heterogenous Clutsers.\nYear: 2015\n\nAbstract: There is currently a growing interest on Big Data Stream processing. With the increasing capabilities of Internet-based computing systems to generate, store and process Big Data Streams, various applications are benefiting from the information extracted in real time from data streams. Such families of applications comprise IoT-based monitoring systems, decision making systems, recommendation systems, security, etc. In all of them, the common ingredient is that of using real time data analytics for the purpose at hand. The foremost challenge of processing Big Data Streams is that of throughput performance, i.e., the computing system should be able to compute at high throughput to accommodate the high data stream rate generation in input. Additionally to this challenge, the processing should be such that the consistency of streaming is achieved. The consistency of streaming requires that the order of events in the original stream (in input) is preserved also in the output. In this paper we show that using a heterogeneous cluster for Big Data Stream processing could indeed incur into streaming inconsistency and one would indeed have to carefully tune the system so that streaming consistency is achieved. We exemplify the approach using the Yahoo!S4 for processing the Big Data Stream from FlightRadar24 global flight monitoring system.","Title: Trustworthiness in Peer-to-Peer Systems.\nYear: 2015\n\nAbstract: A peer-to-peer (P2P) system is composed of peer processes (peers) interconnected in overlay networks. A peer has to communicate only with acquaintance peers due to the scalability and autonomy of the P2P system. A peer can collect information on objects distributed in P2P systems through communicating with the acquaintance peers. Peers may hold obsolete information and be faulty. Hence, a peer has to collect information from trustworthy acquaintance peers. The trustworthiness of an acquaintance peer is defined in terms of multiple parameters like response time and number of correct replies. It is difficult to obtain the trustworthiness due to the complex calculation of multiple parameter. In this paper, we discuss trustworthiness of an acquaintance peer in Fuzzy logics.","Title: Performance Evaluation of a WMN Testbed in Indoor Environment Considering Mobile Mesh Node Scenario.\nYear: 2015\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. Considering mobility of the terminals, routing is a key process for operation of WMNs. In this paper, we present the implementation of a testbed for WMNs. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario considering mobile mesh node. For evaluation we considered throughput, Packet Delivery Ratio (PDR), hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly and we got good values for five parameters.","Title: A Flexible Read-Write Abortion Protocol with Sensitivity of Roles.\nYear: 2015\n\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally and suspiciously reads an object if the object includes data in other objects which are not allowed to be read and the object is suspicious, respectively. A transaction illegally and impossibly writes an object after illegally and suspiciously reading an object, respectively. In this paper, we discuss the flexible read-write-abortion with role sensitivity (FRWA-R) protocol where a transaction is aborted with some probability once illegally reading an object. The abortion ratio depends on the sensitivity of roles which the transaction holds. The sensitivity of a role shows how many transactions which holds the role are aborted after illegally reading an object. The more number of roles to which illegal information flow for a role occur, the lower sensitive the role is. A transaction with lower sensitive roles which illegally reads an object is aborted with higher probability. In the evaluation, we show the execution time of each transaction in the FRWA-R protocol is shorter than the WA protocol and more number of reads can be performed than the RWA protocol.","Title: Performance Evaluation of a Neural Network Based Intrusion Detection System for Tor Networks Considering different Hidden Units.\nYear: 2015\n\nAbstract: Due to the amount of anonymity afforded to users of the Tor infrastructure, Tor has become a useful tool for malicious users. With Tor, the users are able to compromise the non-repudiation principle of computer security. Also, the potentially hackers may launch attacks such as DDoS or identity theft behind Tor. For this reason, there are needed new systems and models to detect the intrusion in Tor networks. In this paper, we present the application of Neural Networks (NNs) for intrusion detection in Tor networks. We used the Back-propagation NN and constructed a Tor server and a Deep Web browser (client). Then, the client sends the data browsing to the Tor server using the Tor network. We used Wireshark Network Analyzer to get the data and then used the Backpropagation NN to make the approximation. We present many simulation results for different number of hidden units. The simulation results show that our simulation system has a good approximation and can be used for intrusion detection in Tor networks.","Title: Suggestion of the Cloud Type Virtual Policy Based Network Management Scheme for the Common Use between Plural Organizations.\nYear: 2015\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leak and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the course between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have been studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. As the second step for the last goal, we show the concept of the cloud type virtual PBNM which can be used by plural organizations in this paper.","Title: Energy-Efficient Broadcast Protocols in Wireless Network\nYear: 2015\n\nAbstract: It is significant to deliver messages to every node in a group to realize the cooperation of the nodes in wireless networks. In order to reduce the number of messages in the flooding protocols, the multi-point relay (MPR) protocols are discussed where only relay nodes forward messages and the other leaf nodes do not forward messages. In this paper, we discuss broadcast protocols where the total electric energy consumed by nodes to deliver messages to every node can be reduced. We newly propose energy-efficient broadcast (EEB) protocol, modified EEB (EEB2) protocol, and augmented EEB (AEEB) protocol. In the EEB protocol, a first-neighbour node to which another first-neighbour node cannot more energy-efficiently deliver messages is selected as a child node of a relay node. In the EEB2 protocol, child nodes are first selected for a relay node in the same way as the EEB protocol. In addition, a farthest child node steps down to a lower level to reduce the electric energy of the relay nodes. In the AEEB protocol, for each uncovered node pi which is a first-neighbour node of the nodes of level l, a node pj of the level l is selected as a parent node of the node pi if the electric energy consumed by the node pj to deliver a message to the node pi is the smallest. We evaluate the EEB and EEB2 protocols and show the total electric energy consumed by nodes can be reduced.","Title: A New FACS for Cellular Wireless Networks Considering QoS: A Comparison Study of FuzzyC with MATLAB.\nYear: 2015\n\nAbstract: Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In this paper, we evaluate the accuracy of implemented Fuzzy-based system written in C-language (FuzzyC) for CAC. For evaluation, we propose a new CAC scheme which considers for acceptance decision except other parameters also the QoS. We compared the performance of FuzzyC with MATLAB. The evaluation results show the FuzzyC has a good accuracy.","Title: Selective Delivery of Event Messages in Peer-to-Peer Topic-Based Publish/Subscribe Systems.\nYear: 2015\n\nAbstract: A distributed system is considered in an eventdriven model where states of processes transit on occurrence of events. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe (P2PPS) system where each peer process (peer) pi can both subscribe a subscription pi:S and publish an event message e with a publication e:P. The subscriptions and publications are specified in terms of topics, i.e. keywords. An event message e is notified to a target peer pi whose subscription pi:S includes a common keyword with the publication e:P. Each event message e carries a vector e:KV = (kv1,
, kvm) of keywords k1,
, km. An event message e1 causally precedes an event message e2 with respect to a subscription Si iff not only e1 causally precedes e2 but also e1:kvh","Title: Multi-level Computation and Power Consumption Models.\nYear: 2015\n\nAbstract: It is critical to reduce the electric power consumed by servers in a cluster in order to realize eco society. In the multi-level power consumption (MLPC) model of a server with a multi-core CPU, the power consumption of the server depends on the number of active cores and active threads where at least one application process is performed. In our previous studies, we discuss the energy-aware (EA) selection algorithm to select a server for each request process. Here, a server which is expected to consume the minimum electric energy is selected in a cluster. A server consumes the basic electric power even if no process is performed. The ratio of the basic energy consumption to the total electric energy consumption is large, e.g. 40 to 50 %. In this paper, we newly propose a globally energy-aware (GEA) algorithm to select a server for each process in a cluster. Here, not only the total electric energy consumption of the servers but also the ratio of basic electric energy consumed by servers to the total energy consumption can be reduced. We evaluate the GEA algorithm and show not only the total energy consumption of the servers but also the average execution time of processes are reduced in the GEA algorithm compared with the EA, round-robin (RR), and random (RD) algorithms.","Title: Trustworthiness-Based Broadcast Protocols in Wireless Networks\nYear: 2015\n\nAbstract: It is significant to deliver messages to every node in a group to realize the cooperation of the nodes in wireless networks. A node sends a message to the neighbour nodes, each of which forwards the message to the neighbour nodes in flooding protocols. Here, a huge number of messages are transmitted in a network. In multi-point relay (MPR) protocols, only a relay node forwards messages and the other leaf nodes do not forward messages in order to reduce the number of messages transmitted in networks. In this paper, we newly discuss trustworthiness concepts of a neighbour node to broadcast messages. The more trustworthy the node is, the more reliably and efficiently the node can forward messages. Trustworthy neighbour nodes are selected as relay nodes. We propose novel types of trustworthiness-based broadcast (TBR) protocols, TBR1 and TBR2 protocols. In the TBR1 protocol, trustworthy first-neighbour nodes are selected as relay nodes. In the TBR2 protocol, each second-neighbour node is connected to a trustworthy first-neighbour node. In the evaluation, electric energy consumed by a node to send messages from a node to the neighbour nodes is considered as trustworthiness of the neighbour node. We evaluate the TBR1 and TBR2 protocols and show the total electric energy consumed by nodes can be more reduced than the MPR protocol.","Title: Optimal Cloud Broker Method for Cloud Selection in Mobile Inter-cloud Computing\nYear: 2015\n\nAbstract: In the next generation of Cloud computing systems (so-called Inter-Cloud), it is expected that multiple Cloud Service Providers (CSPs) will collaborate or cooperate together to form the so-called Cloud Market, with the goal to advertise their services and associate prices to their end users. In this environment, mobile users will be able to better negotiate and select the CSP that better suits their budgetary and technical needs in a more flexible manner. However, despite the benefit of having multiple CSPs to choose from, mobile users will have to cope with several issues, for instance, that of selecting a suitable CSP to handle the incoming service request from the users. To address this problem, this paper proposes an optimal Cloud Broker. The role played by the optimal Cloud Broker is to provide the best possible match for mobile users and CSPs. The Cloud Broker design is formulated by using the framework of Semi-Markov Decision Process (SMDP). Considering the average cost criterion as the optimality criterion, the Value Iteration Algorithm is used to find the optimal Broker policy. Numerical results are presented, demonstrating the effectiveness of our proposed Broker design, in a scenario where a wireless service provider has its own Cloudlet and a Service level Agreement (SLA) has been established with a public CSP to handle the overload occurrences.","Title: Synchronization of Peers in Peer-to-Peer Publish/Subscribe Systems\nYear: 2015\n\nAbstract: In distributed systems, a group of multiple processes are cooperating with one another by exchanging messages in networks. In this paper, we consider a peer-to-peer (P2P) model of a topic-based publish/subscribe (P2PPS) system composed of peer processes (peers). Each peer pi can both subscribe a subscription p\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n. S and publish an event message e with a publication e.P, which are specified in terms topics, i.e. Keywords. An event message e is notified to a target peer p\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n whose subscription p\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n.S includes a common keyword with the publication e.P. Each event message e carries a vector e.V = (V\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n, , V\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">m</sub>\n) of keywords k\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n, , k\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">m</sub>\n. An event message e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n causally precedes an event message e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n with respect to a subscription S\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n iff e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n causally precedes e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n with respect to the send-receive relation and e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n.V\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">h</sub>\n <; e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n.V\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">h</sub>\n for every keyword k\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">h</sub>\n in the publications e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n.P and e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n.P and the subscription p\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">i</sub>\n.S. If a pair of event messages e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n and e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n are ordered so that e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n precedes e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n even if e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n does not causally precede e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n, the event messages e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sub>\n and e\n<sub xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sub>\n are unnecessarily ordered. In this paper, every pair of messages are causally delivered to every common target peer by using the linear clock and keyword vector to reduce pairs of messages unnecessarily ordered. We evaluate the keyword vectors in terms of number of messages unnecessarily ordered.","Title: A Read-Write Abortion Protocol To Prevent Illegal Information Flow In Role-Based Access Control Systems\nYear: 2016\n\nAbstract: In information systems, a transaction may illegally read data stored in an object which the transaction is not allowed to read is stored in the object. A transaction illegally writes data to an object after issuing illegal read. A transaction suspiciously reads data in a suspicious object whose data is not allowed to flow to some object. A transaction impossibly writes data to an object after issuing suspicious read. In our previous studies, the write-abortion (WA) role-based synchronisation (RBS) and object-based synchronisation (OBS) protocols are proposed where a transaction illegally or impossibly writes data to objects is aborted. In this paper, we newly propose a pair of read-write-abortion (RWA) RBS and OBS protocols where a transaction is aborted only if the transaction issues an illegal read or impossible write to an object. In the evaluation, the execution time of each transaction in RWA protocols is shorter than the WA protocols.","Title: Medical Image Analysis by Cognitive Information Systems - a Review.\nYear: 2016\n\nAbstract: This publication presents a review of medical image analysis systems. The paradigms of cognitive information systems will be presented by examples of medical image analysis systems. The semantic processes present as it is applied to different types of medical images. Cognitive information systems were defined on the basis of methods for the semantic analysis and interpretation of information --- medical images --- applied to cognitive meaning of medical images contained in analyzed data sets. Semantic analysis was proposed to analyzed the meaning of data. Meaning is included in information, for example in medical images. Medical image analysis will be presented and discussed as they are applied to various types of medical images, presented selected human organs, with different pathologies. Those images were analyzed using different classes of cognitive information systems. Cognitive information systems dedicated to medical image analysis was also defined for the decision supporting tasks. This process is very important for example in diagnostic and therapy processes, in the selection of semantic aspects/features, from analyzed data sets. Those features allow to create a new way of analysis.","Title: A Web Interface For Satellite Scheduling Problems\nYear: 2016\n\nAbstract: Mission planning plays an important role in satellite control systems, especially with increase of number of satellites and more complex missions to be planned. In a general setting, the satellite mission scheduling consists in allocating tasks such as observation, communication, etc. to resources (spacecrafts (SCs), satellites, ground stations). For instance, in ground station scheduling the aim is to compute an optimal planning of communications between satellites and operations teams of Ground Station (GS). Because the communication between SCs and GSs can be done during specific window times, this problem can also be seen as a window time scheduling problem. The required communication time is usually quite smaller than the window of visibility of SCs to GSs, however, clashes are produced, making the problem highly constrained. In this work we present a web interface for solving satellite scheduling problems through various heuristic methods. The web interface enables the users to remotely solve their problem instances through a selection of heuristic methods such as local search methods (Hill Climbing, Simulated Annealing and Tabu Search) and population-based methods (Genetic Algorithms and variants). The user can select to solve previously generated instances by the STK simulation toolkit or generate their own problem instances. The heuristic methods are easily configurable so that users can simulate a variety of scenarios, problem sizes, etc. The execution of the heuristics methods is done at a HPC Cluster infrastructure supporting efficient execution of various solvers. Additionally, the web application allows users to keep track of their executions as well as to share problem instances with other users.","Title: Energy-Aware Clusters of Servers for Storage and Computation Applications\nYear: 2016\n\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems like cloud computing systems. In clusters, most application processes like web applications use not only CPU resources but also files and databases. In this paper, we consider storage processes which read and write data in files in addition to computation processes. We propose a PCS model (power consumption model for a storage server) which shows how much electric power a server consumes to perform storage and computation processes. We also propose a CS model (a computation model for storage server) which shows how long it is expected to take to perform storage processes and computation processes. By using the PCS and CS models, we propose a local energy-aware (LEA) algorithm to select a server for a request process in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEA algorithm in terms of total electric energy consumption of the servers. We show the electric energy consumed by servers to perform computation and storage processes can be reduced in the LEA algorithm.","Title: Reduction Of Unnecessarily Ordered Event Messages In Peer-To-Peer Model Of Topic-Based Publish/Subscribe Systems\nYear: 2016\n\nAbstract: A distributed system is considered in an event driven model where a state of a process transits on occurrence of an event. In this paper, we discuss a peer-to-peer topic-based publish/subscribe (P2PPS) model where each peer process (peer) can both subscribe and publish event messages. The subscriptions and publications are specified in terms of topics. Each event message e carries a vector e.TV = < tv(1), ..., tv(h)> of topics t(1), ..., t(h) in a system. An event message e(1) causally precedes an event message e(2) with respect to a topic subset T iff not only e(1) causally precedes e(2) but also e(1).tv(j) <= e(2).tv(j) for every topic t(j) in an intersection T of the publications of e(1) and e(2) and the subscription S-i of p(i). A pair of event messages e(1) and e(2) are unnecessarily ordered if e(1).TV <= e(2).TV but e(1) does not causally precede e(2). In this paper, we newly propose a topic-based-causally delivering (TBC) protocol where the linear clock and physical clock are used with topic vectors to reduce the number of pairs of messages unnecessarily ordered. We evaluate the TBC protocol and show the number of pairs of unnecessarily ordered messages is reduced.","Title: Energy-Aware Server Selection Algorithms in a Scalable Cluster\nYear: 2016\n\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In this paper, we extend the multi-level power consumption (MLPC) model and the multi-level computation (MLC) model to a server with multiple CPUs. In this paper, we newly propose a totally energy-aware (TEA) algorithm to select a server for a process in a cluster. Here, servers in a cluster are first classified into subclusters. Each subcluster is characterized in terms of the electric power and computation rate. One server is randomly selected in each subcluster. Then, one server is selected so that the expected electric energy is minimum in the selected servers. We evaluate the TEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the TEA algorithm compared with other algorithms.","Title: Experimental Results of a Raspberry Pi and OLSR Based Wireless Content Centric Network Testbed Considering OpenWRT OS\nYear: 2016\n\nAbstract: The Content Centric Networks (CCN) replaces the IP narrow waist of the Internet architecture by a content layer. When a node wants to access a piece of content, it sends an Interest packet to the network. The network then, using the name of the content for routing, forwards the Interest to one or more copies of the content object. In this paper, we present the implementation of a OpenWRT OS based testbed for CCN. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario. We transmitted single ICMP flow over UDP. For evaluation we considered hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly and we got low values of delay and jitter.","Title: Influential Abortion Probability in a Flexible Read-Write Abortion Protocol\nYear: 2016\n\nAbstract: Data in an object may flow into another object if transactions read and write data in the objects. A transaction illegally reads data in an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the flexible read-write-abortion with role sensitivity (FRWA-R), object sensitivity (FRWA-O), and role safety (FRWA-RS) protocols are proposed to prevent illegal information flow. Here, a transaction aborts with some probability once illegally reading data in an object. The abortionprobability of a transaction depends on the sensitivities of roles which the transaction holds and objects in which the transaction illegally reads data. The safety of a role and object shows how many transactions which hold the role and illegally read data in the object commit or abort after illegally reading data in the object, respectively. Here, safety of a role which increases and decreases by constant values as a transaction holding the role aborts and commits, respectively. Based on the safety concept, we newly propose an influential abortion probability of a transaction where the abortion probability depends on not only roles held by the transaction but also the previous abortion probability. In this paper, we newly propose an FRWA with the influential abortion probability (FRWA-IAP) protocol. In the evaluation, we show a fewer number of transactions abort in the FRWA-IAP protocol than the RWA and FRWA-RS protocols while transactions are more efficiently performed than the WA protocol.","Title: An Energy-Efficient Load Balancing Algorithm for Virtual Machine Environments to Perform Communication Type Application Processes\nYear: 2016\n\nAbstract: Scalable, high performance, and fault-tolerant distributed applications are realized with virtual machines in server cluster systems. Application processes are performed on virtual machines in each server. Processing load of virtual machines to perform application processes has to be balanced in a server cluster system to satisfy the application requirements like response time. On the other hand, a server cluster system consumes a large amount of electric energy since multiple servers consume electric energy to perform application processes. It is critical to discuss how to reduce the total electric energy consumption of a server cluster to perform application processes on virtual machines. In our previous studies, the transmission model and power consumption model of a server to perform communication processes on multiple virtual machines are proposed. In this paper, we newly propose the transmission energy consumption laxity based (TECLB) algorithm to allocate communication processes to virtual machines in a server cluster based on the proposed transmission model and power consumption model of a server so that the total energy consumption of a server cluster can be reduced. We evaluate the TECLB algorithm in terms of the total energy consumption of a server cluster and transmission time of each process compared with the basic round-robin (RR) algorithm. The evaluation results show the average total energy consumption of a server cluster is maximumly reduced to 9% of the RR algorithm.","Title: An Energy-Aware Migration of Virtual Machines\nYear: 2016\n\nAbstract: We have to reduce the electric energy consumed by servers in a cluster. In our previous studies, types of algorithms to select an energy-efficient server for a request process are proposed. Furthermore, schemes for energy-efficiently migrating a process and replicas of a process are discussed where a process and a replica migrate on a host server to a more energy-efficient guest server in our previous studies. However, it is not easy to realize the migration of processes on types of servers. Virtual machine (VM) technologies are now widely used to support applications with virtual resource service in could computing systems. Here, a virtual machine with application processes can migrate from a host server to another guest server. In this paper, we newly propose an energy-aware migration scheme of virtual machines (EAMV). Here, processes on a virtual machine can migrate to a server which consumes smaller electric energy and can be energy-efficiently performed in a cluster. We implement the EAMV scheme and evaluate the migration scheme in terms of energy consumption of servers and execution time of each process.","Title: Examination Of The Implementation Method Of The Cloud Type Virtual Policy Based Network Management Scheme For The Common Use Between Plural Organizations\nYear: 2016\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the course between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. As the second step of the second phase for the last goal, we examine the implementation method of the cloud type virtual PBNM which can be used by plural organizations in this paper.","Title: A Model for Migration of Virtual Machines to Reduce Electric Energy Consumption\nYear: 2016\n\nAbstract: We have to reduce the electric energy consumed by servers in a cluster in order to realize eco-society. Types of algorithms for a request process to select an energy-efficient server in a cluster of servers are proposed in our previous studies. Furthermore, algorithms for energy-efficiently migrating a process on a host server to a more energy-efficient guest server is discussed. Virtual machines are now widely used to support applications with virtual computation service in cloud computing systems. Here, a virtual machine can migrate to a guest server, e.g. which is less loaded. By migrating a virtual machine, application processes performed on the virtual machine can also migrate from a host server to another guest server. In this paper, we newly propose an energy-aware migration algorithm of virtual machines (EAMV). Here, processes on a virtual machine can migrate to a guest server which consumes smaller electric energy and can be energy-efficiently performed in a cluster. We evaluate the EAMV algorithm compared with non-migration algorithms in terms of the total electric energy consumption and execution time of processes. We show the electric energy consumption and average execution time can be reduced in the EAMV algorithm.","Title: A Centrality-Based History Prediction Routing Protocol for Opportunistic Networks\nYear: 2016\n\nAbstract: In Opportunistic networks (OppNets), due to high mobility, short radio range, intermittent links, unstable topology, sparse connectivity, to name a few, routing is a very challenging task since it relies on cooperation between the nodes. This paper focuses on using the concept of centrality to alleviate this task. Unlike other nodes in the network, central nodes are those that are more likely to act as communication hubs to facilitate the message forwarding and thereby routing. In this paper, a recently proposed History-Based Prediction Routing protocol (HBPR) for OppNets is re-designed using this concept, yielding the so-called centrality-based HBPR (CHBPR) routing protocol. The proposed CHBPR scheme is evaluated by simulations using the Opportunistic NEtwork (ONE) simulator, showing superior performance compared to HBPR without centrality and Epidemic protocol with centrality, in terms of number of messages delivered at destination and overhead ratio, under varying number of nodes and Time-to-Live.","Title: Experimental Results of a Raspberry Pi Based Wireless Mesh Network Testbed Considering TCP and LoS Scenario\nYear: 2016\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using Raspbian OS. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor environment considering Transmission Control Protocol (TCP) and Line-of-Sight (LoS) scenario. For evaluation we considered throughput, hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly.","Title: Energy-Aware Algorithms to Select Servers in Scalable Clusters\nYear: 2016\n\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In this paper, we discuss an MLPCM (multi-level power consumption with multiple CPUs) model and an MLCM (multi-level computation with multiple CPUs) model of a server with multiple CPUs. In this paper, we newly propose a modified globally energy-aware (MEA) algorithm to select a server for a process in a cluster of m servers. In the MEA algorithm, a server where a process all is to be performed is selected with computation complexity O(m) if the total electric energy of the servers is minimum. We evaluate the MEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the MEA algorithm compared with other algorithms.","Title: Information Flow Control Models in Peer-to-Peer Publish/Subscribe Systems\nYear: 2016\n\nAbstract: A publish/subscribe (PS) model is an event-driven model of a distributed system. In this paper, we consider a peer-to-peer (P2P) type of PS model where each peer (process) can publish and subscribe events. Here, a peer publishes an event message and then the event message is notified to a target peer which is interested in the event. Publications and subscriptions are specified in terms of topics as discussed in topic-based PS systems. In this paper, we newly discuss a topic-based access control (TBAC) model to prevent illegal information flow among peers in PS systems. Here, an access right is a pair \"t, op\" of a topic t and an operation op which is publish or subscribe. A peer is allowed to publish an event message with topics and subscribe topics only if the topics are granted to the peer. An event message e is notified to a peer pi if the publication of e and subscription of pi include some common topic. If a peer pi publishes an event message e2 after receiving an event message e1, the event message e2 may bring the event of e1, which the peer pi is not allowed to publish. Here, information in the peer pi illegally flow to another peer. We define the legal flow relation among the peers. Then, we newly propose a subscription-based synchronization (SBS) protocol to prevent illegal information flow. Here, a notification is banned if the notification may cause illegal information flow. We evaluate the SBS protocol in terms of number of notifications banned.","Title: The Extended Power Consumption Model to Perform Computation Type Application Processes on Virtual Machines\nYear: 2016\n\nAbstract: Scalable and high performance server cluster systems like cloud computing systems are equipped with virtual machines to efficiently utilize server resources. On the other hand, a large amount of electric energy is consumed in a server cluster system since multiple servers consume electric energy to perform application processes on virtual machines. In order to design and implement an energy-aware server cluster system, the computation model of a virtual machine and power consumption model of a server have to be defined. In our previous studies, we proposed the power consumption model of a server and computation model of a virtual machine to perform application processes on virtual machines. However, the proposed power consumption model and computation model does not consider the change of the clock frequency of each core in a server. In this paper, we consider the change of the clock frequency of each core in a server. Then, we newly proposed the extended power consumption model of a server and computation model of a virtual machine to perform computation type application processes.","Title: Scalable Group Communication Protocols in the Peer-to-Peer Model of Topic-Based Publish/Subscribe Systems\nYear: 2016\n\nAbstract: A distributed system is considered in an event-driven model composed of processes which are sequences of events. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe system (P2PPS model) where each peer process (peer) can both subscribe interesting topics and publish event messages. Since each peer can both publish and receive event messages, a peer may publish an event message e1 after receiving an event message e2. In the P2PPS system, event messages have to be notified to every common target peer in the causal order. In the TBC (topicbased causally delivery) protocol, event messages are causally delivered by taking advantage of physical time in addition to linear time and topic vector. Physical time is used to reduce pairs of event messages unnecessarily ordered. In this paper, we discuss the relation among the clock offset and delay time in the evaluation.","Title: A Model for Energy-Aware Migration of Virtual Machines\nYear: 2016\n\nAbstract: In order to realize eco-society, we have to reduce the electric energy consumed by servers in a cluster in addition to satisfying performance requirements. Virtual machines are now widely used to support applications with virtual computation service in clusters like cloud computing systems. Here, a virtual machine on a host server can migrate to a guest server while processes are being performed on the virtual machine. For example, if the host server of a virtual machine is heavily loaded and a guest server is less loaded, the virtual machine migrates to the guest server. In our previous studies, the EAMV (Energy-Aware Migration of Virtual machines) algorithm is proposed where a virtual machine migrates to a guest server which is expected to consume smaller electric energy to perform processes on the virtual machines. Here, the termination time of each process on each virtual machine is estimated. It is not easy to obtain the state of each process and take time to calculate the expected termination time. In this paper, a virtual machine is considered to be a unit of computation. Termination time of a virtual machine, i.e. time when every process is to terminate on the virtual machine'C is estimated by considering the virtual machines.","Title: An Eco Model of Process Migration with Virtual Machines\nYear: 2016\n\nAbstract: It is critical to reduce the electric energy consumed by servers in clusters. In cloud computing systems, computation resources like CPU, memory, and storages are virtualized so that applications can use the resources without being conscious of which physical servers supports which service. Virtual machine technologies are now used to support applications with virtual computation service. Virtual machines are used to perform application processes issued by clients. More importantly, virtual machines can migrate from a host server to a guest server while processes are being performed on the virtual machines. In this paper, we take advantage of migration technologies of virtual machines to reduce the electric energy consumed by servers in a cluster. By using the virtual machines, we propose an energyaware migration model of processes to decide to which virtual machine a process issued by a client is allocated and which virtual machine migrates to another energy-efficient server in order to reduce the electric energy consumption.","Title: Power Control Scheme for Underlay Approach in Cognitive Radio Networks\nYear: 2016\n\nAbstract: In this paper, a conflict-graph based power control scheme for spectrum underlay in cognitive radio networks is proposed, which helps avoiding the interference and saving power when the primary and secondary users share the same channel simultaneously. Simulations results using the OMNet++ simulator are provided, showing the effectiveness of the proposed approach in terms of number of users in the network, interference imposed by the secondary users on the primary users, Signal to Interference plus Noise Ratio (SINR), and power saving.","Title: Performance Analysis of WMNs by WMN-GA Simulation System for Different WMN Architectures and TCP Congestion-Avoidance Algorithms Considering Uniform Distribution\nYear: 2016\n\nAbstract: In this paper, we evaluate the performance of two Wireless Mesh Networks (WMNs) architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3, Distributed Coordination Function (DCF) and Optimized Link State Routing (OLSR). We compare the performance for Transmission Control Protocol (TCP) Tahoe, Reno and NewReno for uniform distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for both WMN architectures, the PDR values of TCP congestion-avoidance algorithms are almost the same. For Hybrid WMN architecture, the throughput of TCP Reno is better than other algorithms. However, for I/B WMN, the throughput of TCP Tahoe is higher than other algorithms. The delay and jitter of TCP NewReno are a little bit lower compared with other algorithms. The I/B WMN architecture, the fairness index of TCP congestion-avoidance algorithms is almost the same.","Title: Selection Algorithms to Select Energy-Efficient Servers for Storage and Computation Processes\nYear: 2016\n\nAbstract: It is now critical to reduce electric energy consumed by servers in a cluster, especially scalable systems like cloud computing systems. In a cluster of servers, most application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the power consumption MLPCS model and computation MLCMS model are proposed. Ways to energy-efficiently perform processes which use either CPU or storages are discussed in a cluster of servers. In this paper, we consider a more general type of process which does both the computation and accesses to storages. By using the MLPCMS and MLCMS models, we propose LEAS and GEAS algorithms to select servers to perform processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the algorithms in terms of total electric energy consumption of the servers and average execution time of the processes. We show the electric energy consumed by servers can be reduced in the LEAS and GEAS algorithms.","Title: A Neural Network Based User Identification For Tor Networks: Comparison Analysis Of Different Activation Functions Using Friedman Test\nYear: 2016\n\nAbstract: In this paper, we present the application of Neural Networks (NNs) for user identification in Tor networks. We used the Back-propagation NN and constructed a Tor server, a Deep Web browser (Tor client) and a Surface Web browser. Then, the client sends the data browsing to the Tor server using the Tor network. We used Wireshark Network Analyzer to get the data and then used the Back-propagation NN to make the approximation. For evaluation we considered Number of Packets (NoP) metric and activation function. We analyze the data using Friedman test. From the results, we adopt null hypothesis H-0 since p < 0.05 for all activation functions. However, the softsign/x has the smallest p-value among activation functions. Therefore, it is better to use softsign/x for bad user identification in Tor networks.","Title: Multi-level Power Consumption and Computation Models and Energy-Efficient Server Selection Algorithms in a Scalable Cluster\nYear: 2016\n\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In ourprevious studies, the MLPCM (multi-level power consumption with multiple CPUs) and MLCM (multi-level computation with multiple CPUs) models are proposed with server selection algorithms. In the server selection algorithms, a server is selected to perform a process issued by a client by estimating the electric energy consumption by simulating the execution of every current process. However, it takes time to collect the state of processes performed on each server and estimate the termination time of the processes. In this paper, we propose a simple energy-efficient (PEA) algorithm to select server where only state information on number of processes on each serveris used. We evaluate the PEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the PEA algorithm compared with other algorithms.","Title: Experimental Results of a Raspberry Pi Based WMN Testbed in Indoor Environment: A Comparison Study of LoS and NLoS Scenarios\nYear: 2016\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using OpenWRT OS. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor environment considering Line-of-Sight (LoS) and Non Line-of-Sight (NLoS) scenarios. For evaluation we considered throughput, Packet Delivery Ratio (PDR), hop count, delay and jitter metrics. The experimental results show that the performance of the testbed was better for LoS scenario. Also, the nodes in the testbed were communicating smoothly.","Title: The Improved Redundant Delay Time-Based (IRDTB) Algorithm to Perform Computation Type Application Processes in Heterogeneous Server Clusters\nYear: 2016\n\nAbstract: In fault-tolerant information systems, application processes have to be reliably performed in presence of server faults. Server cluster systems are widely used to realize not only high performance but also fault-tolerant service. In order to reliably perform application processes, multiple replicas of each application process are performed on multiple servers in a server cluster system. On the other hand, the larger amount of electric energy is consumed in a server cluster system since multiple replicas of each application process are performed on multiple servers. The redundant delay time based (RDTB) algorithm is discussed to select multiple servers to redundantly perform each application process in a homogeneous server cluster so that the total energy consumption of the server cluster can be reduced. In a homogeneous cluster, every server follows the same computation model and power consumption model. On the other hand, servers follow different types of computation models and power consumption models in a heterogeneous server cluster. Hence, a load balancer cannot precisely estimate the processing load and energy consumption of each server in a heterogeneous server cluster by the RDTB algorithm. In this paper, we propose an improved RDTB (IRDTB) algorithm to select multiple servers for redundantly performing each application process so that the total energy consumption of a server cluster and response time of each process in a heterogeneous server cluster can be reduced. We evaluate the IRDTB algorithm compared with the RDTB algorithm in a heterogeneous server cluster. In the evaluation, we show the average total energy consumption of a heterogeneous server cluster in the IRDTB algorithm can be reduced maximum 44% of the RDTB algorithm.","Title: Subscription Initialization (SI) Protocol to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems\nYear: 2016\n\nAbstract: In a peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer (process) caP2P) typen be a publisher and subscriber. Here, a peer publishes an event message and then the event message is notified to a target peer which is interested in the event message. Publications and subscriptions are specified in terms of topics. In the topic-based access control (TBAC) model proposed in our previous studies, only a peer granted publication and subscription access rights is allowed to publish event messages with publication topics and subscribe events, respectively. In our previous studies, the illegal information flow relation among peers is defined and the subscription-based synchronization (SBS) protocol is proposed to prevent illegal information flow. Here, topics carried by event messages are just accumulated in the target peers and notification of event messages which may cause illegal information flow are banned in each target peer. The more number of event messages are published, the more number of event messages are not notified in the system. In this paper, we newly propose a subscription initialization (SI) protocol where topics accumulated in peers are removed to reduce the number of notifications banned. We show the number of notifications banned is reduced in the SI protocol compared with the SBS protocol in the evaluation.","Title: Topic-Based Causally Ordered Delivery of Event Messages in a Peer-to-Peer (P2P) Model of Publish/Subscribe Systems\nYear: 2016\n\nAbstract: An event-driven publish/subscribe (PS) model of a distributed system is used in various applications. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based PS system (P2PPS model) where each peer process (peer) can both subscribe interesting topics and publish event messages with topics. In our previous studies, we propose the TBC (topicbased causally delivery) protocol an homogeneous networks where maximum delay time between every pair of peers is same. Here, a pair of event messages are checked if the event messages are related in the topic vector and are causally delivered by taking advantage of physical time and linear time. In this paper, we consider a system where peers are interconnected in heterogeneous networks. Here, maximum delay time between every pair of peers is not same. We propose a heterogeneous TBC (HTBC) protocol where event messages are TBC-causally delivered to target peers in heterogeneous network. We evaluate the HTBC protocol and show the number of pair of event messages unnecessarily ordered is reduced in the HTBC protocol.","Title: An Energy-Efficient Routing Protocol for Infrastructure-Less Opportunistic Networks\nYear: 2016\n\nAbstract: In this paper, an energy-aware version of a recently proposed History-Based Prediction for Routing (HBPR) protocol for opportunistic networks (OppNets) called energy-efficient HBPR (AEHBPR) is proposed, which saves the energy consumption by avoiding unnecessary packets transmission in the network and by clearing the buffer of nodes carrying the copies of the already delivered packets. The proposed AEHBPR is simulated using the ONE simulator, using synthetic and real mobility traces, showing a superior performance compared to HBPR and AEProphet, in terms of average remaining energy, number of dead nodes, number of delivered messages, and overhead ratio, where AEProphet is the ProPHet routing protocol for OppNets, on which the same energy-aware mechanism has been implemented.","Title: Performance Analysis of a Genetic Algorithm Based System for Wireless Mesh Networks Considering Weibull Distribution, DCF and EDCA\nYear: 2016\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for Weibull distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for I/B WMN, the throughput of both MAC protocols is higher than Hybrid WMN. The delay and jitter of both architectures are almost the same. However, for 10 flows, the delay and jitter of I/B WMN is a lower compared with Hybrid WMN. The fairness index is a almost the same for both WMN architectures.","Title: Design and Evaluation of Algorithms to Energy-Efficiently Select Servers for Storage and Computation Processes\nYear: 2016\n\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems like cloud computing systems. In clusters, most application processes like web applications use not only CPU but also storages like databases. In this paper, we consider storage processes which read and write data in files in addition to computation processes. We propose an MLPCMS (power consumption model for a storage server) model which shows how much electric power a server consumes to perform storage and computation processes. We also propose an MLCMS (computation model for a storage server) model which shows the expected execution time of storage and computation processes. By using the MLPCMS and MLCMS models, we propose a GEAS (globally energy-aware server with storage processes) algorithm to select servers to perform computation and storage processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the GEAS algorithm in terms of total electric energy consumption of the servers. We show the electric energy consumed by servers can be reduced in the GEAS algorithm.","Title: Energy-Aware Analysis of Synchronizing a Groupware Calendar\nYear: 2016\n\nAbstract: With the fast development in Internet and Mobile technologies, we are witnessing a proliferation of applications that support online collaborative group work. Such applications offer many advantages as compared to traditional web-based online collaborative learning, the most salient feature being the ability to work not only geographically distributed but also on the move, anytime and anywhere. Such applications in the very recent past used to offer lightweight client applications, leaving the burden of the application logics to the server side applications. However, as mobile devices are each time more powerful in terms of computing and storage capacity, client applications at mobile device are each time more complex and heavy so that members of the group could be able to work both offline and online, which arises when members of the group use smartphones and can eventually run out of Internet connection from time to time, or simply want to develop some activities locally. This comes to the price of wasting the battery in shorter time and thus impeding the collaborative work for longer time intervals. Due to this reason, researchers and developers are interested to develop sophisticated mobile applications under energy-aware requirements. In this work we analyse the energy efficiency of a group calendar that offers 1) information sharing among all of members of the group, 2) synchronisation among local calendars of members and global group calendar, 3) conflict resolution through a voting system, 4) awareness of changes in the entries (tasks, members, events, etc.) of the calendar and 5) sharing of calendars among different groups. In particular, we analyse the energy efficiency due to the synchronisations mechanisms employed by a group calendar as synchronisation is among most compute intensive and time consuming tasks. Our study sheds light on the need of implementing various synchronisation mechanisms from lightweight synchronisation to full synchronisation and their applications according to energy profile of the mobile device.","Title: Personalized cryptography in cognitive management.\nYear: 2017\n\nAbstract: One of the existing problems of information management is an information security. In this aspects one of possible solution is divide information between a group of persons authorized to manage this information. Information sharing processes allow to protect the information from disclosure. In this paper, the process of division of the information has been enhanced by biometric identification stage. Secure information processes with biometric identification are used to manage very important and strategic data. This paper presents the questions of personal cryptography understood as a combination of the tasks of classifying information and biometric techniques used for this kind of tasks. The techniques of biometric data marking are present on the examples of data division and sharing protocols, expanded by the stages of personal identification and verification. This kind of solutions is presented for the tasks of dividing appropriately the shared secret information. Moreover, we shall present the management process of shadow sets, i.e., of parts of the divided, secret information. The processes of secret data management are refer to tasks of cognitive management, understood as management executed on the basis of understanding the meaning of the processed data.","Title: An energy-aware algorithm to migrate virtual machines in a server cluster.\nYear: 2017\n\nAbstract: In order to realise eco-society, we have to reduce the electric energy consumed by servers in a cluster in addition to satisfying performance requirements. Virtual machines are now widely used to support applications with virtual computation service in clusters of servers. Here, a virtual machine on a host server can migrate to a guest server while processes are being performed on the virtual machine. In this paper, we propose an energy-aware migration of virtual machines EAMV algorithm where not only a virtual machine is selected to perform a process issued by a client but also a virtual machine migrates to a guest server which is expected to consume smaller electric energy to perform processes on the virtual machine. In the evaluation, we show the total electric energy consumption of servers and the average execution time of processes can be reduced in the EAMV algorithm compared with non-migration algorithms.","Title: Effect of Node Density and Node Movement Model on Performance of a VDTN.\nYear: 2016\n\nAbstract: In this paper, we evaluate the effect of node density and node movement model in a many-to-one communication in a Vehicular Delay Tolerant Network (VDTN). Seven groups with three stationary sensor nodes sense the temperature, humidity and wind speed and send these data to a stationary destination node that collect them for statistical and data analysis purposes. Vehicles moving in Tirana city roads during the opportunistic contacts will exchange the sensed data to destination node. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. For the simulations we considered two different scenarios where the distance of the source nodes from the destination is short and long. The performance is analyzed for three routing protocols for delivery probability and average latency metrics. For both scenarios the effect of node density and node movement model is evaluated. The simulation results show that the increase of node density increases the delivery probability for all protocols and both scenarios, and better results are achieved when shortest-path map-based movement model is used.","Title: Energy-aware Migration of Virtual Machines in a Cluster.\nYear: 2016\n\nAbstract: In order to realize eco-society, we have to reduce the electric energy consumed by servers. Virtual machines are now widely used to support applications with virtual computation service in server clusters. Here, a virtual machine can migrate to a guest server while processes are being performed. In the EAMV algorithm we previously proposed, the termination time of each process on each virtual machine has to be estimated. However, it is not easy to obtain the state of each process and takes time to calculate the expected termination time. In this paper, we newly propose a virtual machine migration (VMM) algorithm where termination time of each virtual machine is estimated without considering each process. We evaluate the VMM algorithm and show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the VMM algorithm compared with non-migration algorithms. The VMM algorithm is simpler than the EAMV algorithm","Title: An Energy-efficient Migration Model of Processes with Virtual Machines in a Server Cluster.\nYear: 2016\n\nAbstract: In cloud computing systems, computation resources like CPU and storages are virtualized. Virtual machines are now widely used to support applications with virtual computation service and to perform application processes. Furthermore, virtual machines can migrate from a host server to a guest server while processes are being performed on the virtual machines. We have to reduce electric energy consumption of servers in server clusters. In this paper, we take advantage of the migration technologies of virtual machines to reduce the electric energy consumed by servers. We propose a simple virtual machine migration (SVM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. We show the total electric energy consumption of the servers can be reduced in the SVM algorithm.","Title: An Energy-efficient and Reliable Protocol in Wireless Networks.\nYear: 2016\n\nAbstract: In recent years, wireless ad-hoc networks which do not use network infrastructure are getting more important in various applications like vehicle-to-vehicle (V2V) networks. Especially, it is easy for nodes to communicate with one another without network infrastructure like access points and base stations. Here, ad-hoc routing protocols are needed to deliver messages to destination nodes. In wireless ad-hoc networks, neighbor nodes with which each node can directly communicate may be changed, e.g due to movement of nodes and faults of nodes. Besides, since nodes in ad-hoc networks work with their electric batteries, it is required to reduce electric energy consumed by nodes to send and receive messages. It is difficult to always find a best route to a destination node due to complex parameters like bandwidth and message loss ratio. In this paper, we newly propose a reliable one-to-one communication protocol named TBAH (Trustworthiness-Based Ad-Hoc communications) protocol where routes to the destination nodes are found by using the fuzzy logic in wireless networks.","Title: Comparison Analysis by WMN-GA Simulation System for Different WMN Architectures, Normal and Uniform Distributions, DCF and EDCA Functions.\nYear: 2016\n\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for normal and uniform distributions of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for normal distribution, the throughput of I/BWMNis higher than Hybrid WMN architecture. For uniform distribution, in case of I/B WMN, the throughput of EDCA is a little bit higher than Hybrid WMN. However, for Hybrid WMN, the throughput of DCF is higher than EDCA. For normal distribution, the delay and jitter of Hybrid WMN is lower compared with I/B WMN. For uniform distribution, the delay and jitter of both architectures are almost the same. However, in the case of DCF for 20 flows, the delay and jitter of I/B WMN is a lower compared with Hybrid WMN. In normal distribution case, the fairness index of 10 and 20 flows is higher than 30 flows for both WMN architectures. For I/B architecture the fairness index of DCF is higher than EDCA. However, for Hybrid WMN, the fairness index of EDCA is higher than DCF. For uniform distribution, the fairness index of 10 flows is higher than other flows for both WMN architectures.","Title: Energy-aware Server Selection Algorithms for Storage and Computation Processes.\nYear: 2016\n\nAbstract: Application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the algorithms to select a server in a cluster are proposed to energy-efficiently perform processes which use either CPU or storages. In this paper, we consider a more general type of process which does both the computation and accesses to storages. In this paper, we newly propose LEAG and GEAG algorithms to select servers to perform general processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEAG and GEAG algorithms in terms of total electric energy consumption of the servers and average execution time of the processes. We show the electric energy consumed by servers can be reduced in the LEAG and GEAG algorithms.","Title: Simple Energy-efficient Server Selection Algorithm in a Scalable Cluster.\nYear: 2016\n\nAbstract: It is critical to reduce the electric energy consumed in server clusters. In our previous studies, the MLPCM and MLCM models are proposed with LEA and MEA server selection algorithms. Here, a server is selected to perform a process by estimating the termination time of every current process. However, it takes time to collect the state of each process and estimate the termination time of each process. In this paper, we propose a simple energy-aware (PEA) algorithm to select a server where only state information on number of processes on each server is used. In the evaluation, we show the computation complexity of the PEA algorithm is O(1), smaller than the other algorithms while the total electric energy consumption of the servers of the PEA algorithm is almost the same as the MEA algorithm and is smaller than the others.","Title: Topic-based Synchronization (TBS) Protocols to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems.\nYear: 2016\n\nAbstract: In a peer-to-peer type of topic-based publish/subscribe (P2PPS) model, each peer (process) can publish an event message and receive an event message in which the peer is interested. Subscription of a peer and publication of an event message are specified in terms of topics. In the topic-based access control (TBAC) model proposed in our previous studies, only a peer granted publication and subscription rights is allowed to publish event messages with publication topics and to subscribe events, respectively. In our previous studies, the subscription-based synchronization (SBS) and subscription initialization SBS (SI-SBS) protocols are proposed where notifications which may cause illegal information flow are banned to prevent illegal information flow. It is checked whether or not an illegal information flow to occur in terms of subscription and publication rights granted to each peer. However, even some legal notifications are banned while no illegal event message is notified. In this paper, we newly propose a topic-based synchronization (TBS) and subscription initialization TBS (SI-TBS) protocols where only topics which each peer manipulates are considered. We show the number of notifications banned is reduced in the TBS and SI-TBS protocols compared with the SBS and SI-SBS protocols in the evaluation.","Title: Energy-Efficient Quorum Selection Algorithm for Distributed Object-Based Systems.\nYear: 2017\n\nAbstract: Distributed applications are composed of multiple objects and each object is replicated in order to increase reliability, availability, and performance. On the other hand, the larger amount of electric energy is consumed in a system since multiple replicas of each object are manipulated on multiple servers. In this paper, the energy efficient quorum selection (EEQS) algorithm is proposed to construct a quorum for each method issued by a transaction in the quorum based locking protocol so that the total electric energy consumption of servers to perform methods can be reduced. We show the total energy consumption of servers, the average execution time of each transaction, and the number of aborted transactions can be reduced in the EEQS algorithm compared with the random algorithm in the evaluation.","Title: Energy-Aware Dynamic Migration of Virtual Machines in a Server Cluster.\nYear: 2017\n\nAbstract: Virtual machines are now widely used to support applications with virtual computation service in server clusters. Here, a virtual machine can migrate from a host server to a guest server while processes are being performed. In this paper, we discuss a virtual machine migration approach to reducing the electric energy consumption of servers. In our previous studies, virtual machines are fixed in a cluster. In this paper, we consider a cluster where virtual machines are dynamically created and dropped. We propose a dynamic virtual machine migration (DVMM) algorithm to reduce the total electric energy consumption of servers. We evaluate the DVMM algorithm and show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced compared with other non-migration algorithms.","Title: An Energy-Efficient Migration Algorithm of Virtual Machines in Server Clusters.\nYear: 2017\n\nAbstract: Virtual machines are now widely used to support applications with virtual service on computation resources. Furthermore, a virtual machine can migrate from a host server to a guest server while processes are being performed. In this paper, we propose a Simple Energy-aware Migration (SEAM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. Here, the amount of computation to be performed by processes on a virtual machine is simply estimated only by using the number of the processes. We show the total electric energy consumption of the servers can be reduced in the SEAM algorithm compared with non-migration algorithms in the evaluation.","Title: A GA-Based Simulation System for WMNs: Performance Analysis for Different WMN Architectures Considering Weibull Distribution, HWMP and TCP Protocols.\nYear: 2017\n\nAbstract: In our previous work, we implemented WMN-GA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we evaluate the performance of Weibull distribution of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. We compare the performance of both architectures. The simulation results show that the PDR for both WMN architectures is almost the same. The throughput of I/B WMN is a little bit higher than Hybrid WMN. The delay of Hybrid WMN is lower than I/B WMN. The fairness index and the remaining energy for both WMN architectures are almost the same.","Title: Flexible Synchronization Protocol to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems.\nYear: 2017\n\nAbstract: In the peer-to-peer type of topic-based publish/subscribe (P2PPS) model, each peer (process) can publish event messages and event messages are notified to target peers with no centralized coordinator. Some information of a peer may flow to target peers by publishing an event message. Here, a target peer recognizes an event message to be related with topics which are in a publication of the event message and the peer subscribes. On the other hand, the peer forgets topics which are in a publication of the event message but not in a set of topics which the peer subscribes. We have to prevent illegal information flow to occur by flowing the forgotten topics. In this paper, we newly propose a flexible synchronization (FS) protocol and a relevance concept of topics to prevent illegal information flow to be caused by the forgotten topics. In the FS protocol, even if an event message carries forgotten topics, a peer accepts the event message if the forgotten topics are related with the subscription topics. In the evaluation, the number of illegal information flows decreases in the FS protocol.","Title: Simple Energy-Aware Algorithms for Selecting a Server in a Scalable Cluster\nYear: 2017\n\nAbstract: It is critical to reduce the electric energy consumed in server clusters in order to realize eco society. In our previous studies, a server is selected to perform a process by estimating the termination time of every current process and then the electric energy consumption of servers. However, it is not easy and takes time to collect the state of each process and estimate the termination time of each process. In this paper, we propose SLEA (simple locally energy-aware) and SGEA (simple globally energy-aware) algorithms to select a server where only the number of processes on each server is used. In the evaluation, we show the electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the SLEA and SGEA algorithms.","Title: Design and Implementation of a Simulation System Based on Deep Q-Network for Mobile Actor Node Control in Wireless Sensor and Actor Networks\nYear: 2017\n\nAbstract: A Wireless Sensor and Actor Network (WSAN) is a group of wireless devices with the ability to sense physical events (sensors) or/and to perform relatively complicated actions (actors), based on the sensed data shared by sensors. This paper presents design and implementation of a simulation system based on Deep Q-Network (DQN) for mobile actor node control in WSANs. DQN is a deep neural network structure used for estimation of Q-value of the Q-learning method. In this work, we implement the proposed simulating system by Rust programming language. We describe the design and implementation of the simulation system, and show some simulation results to evaluate its performance.","Title: Algorithms to Energy-Efficiently Select a Server for a General Process in a Scalable Cluster\nYear: 2017\n\nAbstract: Application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the algorithms to select a server in a cluster are proposed to energy efficiently perform processes which use either CPU or storages. In this paper, we consider a more general type of processes which do both the computation and access to storages. In this paper, we propose a computation model of a server to perform general processes and a pair of LEAG (locally energy-aware) and GEAG (globally energy-aware) algorithms to select servers to perform general processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEAG and GEAG algorithms and show the electric energy consumed by servers and the average execution time of processes can be reduced in the LEAG and GEAG algorithms.","Title: Differentiating the Starting Time of Computation Process Replicas in the Improved Redundant Delay Time-Based (IRDTB) Algorithm\nYear: 2017\n\nAbstract: Server cluster systems are widely used to provide not only scalable but also fault-tolerant distributed application services. Each application process has to be reliably performed in presence of server fault to provide reliable application services. One way to reliably perform an application process is that replicas of each application process are performed on multiple servers. However, a larger electric energy is consumed in a server cluster since multiple replicas are performed on multiple servers. In our previous studies, the improved redundant delay time-based (IRDTB) algorithm is proposed to select multiple servers for redundantly and energy efficiently performing computation type application processes in a server cluster. In the IRDTB algorithm, a request process broadcasts to multiple servers and replicas for the request process starts almost at the same time on each server. Here, once a replica successfully terminates on one server, replicas being or to be performed on other servers are meaningless. In this paper, we newly propose an extended IRDTB (EIRDTB) algorithm to furthermore reduce the total energy consumption of a server cluster by forcing meaningless replicas to terminate and differentiating the starting time of each replica. In the EIRDTB algorithm, a request process is serially sent to each server every δ time unit. We evaluate the EIRDTB algorithm in terms of total energy consumption of a server cluster and the average response time of each process compared with the IRDTB algorithm. The evaluation results show the longer inter-request time δ, the smaller amount electric energy is consumed in the EIRDTB algorithm than the IRDTB algorithm.","Title: Energy-Aware Virtual Machine Migration Models in a Scalable Cluster of Servers\nYear: 2017\n\nAbstract: In clusters of servers like cloud computing systems, computation resources like CPUs and storages are virtualized. Virtual machines are now widely used to support applications with virtual computation service on computation resources. Application processes are performed on virtual machines independently of which servers of which architectures are used. Furthermore, a virtual machine can migrate from a host server to a guest server while processes are being performed on the virtual machines. In this paper, we take advantage of the migration technologies of virtual machines to reduce the electric energy consumed by servers. We propose a modified simple virtual machine migration (MSVM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. Here, the amount of computation to be performed by processes on a virtual machine is estimated only by using the number of the processes. We show the total electric energy consumption of the servers can be reduced in the MSVM algorithm compared with non-migration algorithms.","Title: A GA-Based Simulation System for WMNs: Performance Analysis for Different WMN Architectures Considering Exponential Distribution, HWMP and TCP Protocols\nYear: 2017\n\nAbstract: In our previous work, we implemented WMNGA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we evaluate the performance of two different distributions of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. We compare the performance of both architectures for exponential distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the PDR for both WMN architectures is almost the same. The throughput of I/B WMN is higher than Hybrid WMN. The delay of I/B WMN is lower than Hybrid WMN. The fairness index of Hybrid WMN is higher than I/B WMN. For I/B WMN architecture, the energy decreases faster than Hybrid WMN.","Title: Load Experiment of the Cloud Type Virtual Policy Based Network Management Scheme for the Common Use between Plural Organizations\nYear: 2017\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, as the progression phase for the last goal, we perform the load experiment of the cloud type virtual PBNM, which can be used by plural organizations.","Title: Topic-Based Selective Delivery Of Event Messages In Peer-To-Peer Model Of Publish/Subscribe Systems In Heterogeneous Networks\nYear: 2017\n\nAbstract: In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe (PS) system (P2PPS model) where each peer process (peer) can both subscribe and publish event messages with topics and there is no centralized coordinator. Each peer has to causally deliver event messages in which the peer is interested. In our previous studies, the TBC (topic-based causally delivery) protocol is proposed for a homogeneous synchronous network where maximum delay time between every pair of peers is the same and the maximum clock offset of each peer is the same. In this paper, we propose a heterogeneous TBC (HTBC) protocol where peers are interconnected in heterogeneous networks where maximum delay time between every pair of peers and maximum clock offset of each peer may not be the same. In the evaluation, we show the number of pairs of event messages unnecessarily ordered is reduced in the HTBC protocol.","Title: Sensitivity-Based Synchronisation Protocol To Prevent Illegal Information Flow Among Objects\nYear: 2017\n\nAbstract: In information systems, a transaction may illegally read data stored in an object, which the transaction is not allowed to read. A transaction illegally writes data to an object after issuing illegal read. The write-abortion (WA), read-write-abortion (RWA) and flexible RWA (FRWA) protocols to prevent illegal information flow are proposed in our previous papers. In the WA and RWA, a transaction is aborted once issuing an illegal write and illegal read, respectively. In the WA, some reads are meaninglessly performed. In the RWA, some reads are lost. In the FRWA, a transaction is aborted with some probability once issuing illegal read. We newly introduce an object sensitivity concept to decide on the abortion probability. In the evaluation, the execution time of each transaction in the FRWA with object sensitivity is shorter than the WA and more number of reads can be performed than the RWA.","Title: Eco Models of Distributed Systems.\nYear: 2017\n\nAbstract: It is critical to reduce electric energy consumed in information systems, especially servers in scalable clusters, in order to realize eco society. In this paper, we take the macro-level approach to reducing the electric energy consumption of servers. Here, we aim at reducing the total energy consumed by a server to perform application processes. First, we discuss power consumption models which give electric power to be consumed by a server to perform application processes. We also discuss computation models of a server which give execution time of application processes. Based on the models, we discuss algorithms to select an energy-efficient server to perform an application process issued by a client. We also discuss algorithms to migrate processes on host servers to more energy-efficient servers by using virtual machines.","Title: Load Experiments of the vDACS Scheme in Case of the 600 Connections by 300 Clients.\nYear: 2017\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, as the progression phase for the last goal, we perform the load experiment of the cloud type virtual PBNM named the vDACS Scheme, which can be used by plural organizations, for applications to the small and medium size scale organization. The number of clients used in an experiment is 600.","Title: Energy-Efficient Role Ordering Scheduler.\nYear: 2017\n\nAbstract: In information systems, conflicting methods issued by multiple transactions have to be serialized to keep objects mutually consistent. There are various ways to serialize multiple conflicting transactions like timestamp ordering (TO) and FIFO schemes. In this paper, the energy efficient role ordering (EERO) scheduler is proposed to not only serialize multiple conflicting transactions in the significant order of subjects but also reduce the total energy consumption of servers by omitting meaningless methods.","Title: A Simple Energy-Aware Virtual Machine Migration Algorithm in a Server Cluster.\nYear: 2017\n\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where virtual machines with application processes migrate to more energy-efficient servers. In the SEAM algorithm previously proposed, a host server to perform a process and to migrate a virtual machine is selected whose expected electric energy consumption is minimum. In this paper, the SEAM algorithm is improved where a host server is selected with minimum expected electric energy consumed by not only the host server but also the other servers. We show the total electric energy consumption of the servers can be reduced in the improved SEAM (ISEAM) algorithm compared with non-migration algorithms and the SGEA algorithm in the evaluation.","Title: An Energy-Aware One-to-one Routing Protocol in Wireless Ad-Hoc Network.\nYear: 2017\n\nAbstract: In wireless ad-hoc networks, messages are exchanged among nodes in wireless communication networks in ad-hoc routing protocols. Here, the electric energy consumed by nodes to send messages has to be reduced. The ESU (Energy-Saving Unicast routing) protocol is proposed in our previous study, where the electric energy consumption of each node can be reduced, but the length of source-destination route, i.e. number of nodes increases. In this paper, we newly propose an EAO (Energy Aware One-to-one routing) protocol to shorten the length of a route and reduce the total electric energy consumption of nodes in a route. In the evaluation, we show the total electric energy consumption of nodes in a source-destination route can be reduced in the EAO protocol compared with other protocols.","Title: A GA-Based Simulation System for WMNs: A Comparison Study for Different WMN Architectures Considering Exponential and Weibull Distributions, HWMP and TCP Protocols.\nYear: 2017\n\nAbstract: In our previous work, we implemented WMN-GA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we compare the performance of Exponential and Weibull distributions of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. The simulation results show that the PDR for both distributions is almost the same. The throughput of Exponential distribution is a little bit higher than Weibull distribution. The delay of Weibull distribution is lower than Exponential distribution. For Hybrid WMN, the fairness index of Exponential distribution is higher than Weibull distribution. But for I/B WMN, the fairness index of Weibull distribution is higher than Exponential distribution.","Title: An Eco Algorithm for Dynamic Migration of Virtual Machines in a Server Cluster.\nYear: 2017\n\nAbstract: Electric energy consumed in server clusters has to be reduced. In our previous studies, the dynamic virtual machine migration (DVMM) algorithm is proposed to reduce the total electric energy consumption of servers. In this paper, we improve the DVMM algorithm to furthermore reduce the electric energy consumption. If an application issues a process to a cluster, a most energy-efficient host server is first selected and the process is performed on a virtual machine on the server. Then, a virtual machine migrates from a host server to a more energy-efficient guest server. In the evaluation, we show not only the total electric energy consumption and active time of servers but also the average execution time of processes can be reduced in the DVMM algorithm compared with other algorithms.","Title: Security of Visual Captcha for Authentication Procedures.\nYear: 2017\n\nAbstract: In this paper will be described new idea of security procedures using visual captcha, and dedicated to authentication procedures. In particular will be presented the most important aspects connected with security of visual captcha used in security procedures, implemented in service management solutions in Cloud environment. Services management in Cloud Computing will be connected with application of secure cognitive information and cognitive management systems, supporting management activities and securing data using visual captcha solutions.","Title: Evaluation of Flexible Synchronization Protocol to Prevent Illegal Information Flow in P2PPS Systems.\nYear: 2017\n\nAbstract: We consider the peer-to-peer type of topic-based publish/subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. Some information of a peer may flow to target peers by exchanging event messages. Here, the peer forgets topics which are in a publication of the event message but not in the subscription of the peer. In our previous studies, the flexible synchronization (FS) protocol and the relevance concept of topics are proposed. However, it is difficult, maybe impossible for each peer to know about every topic in a system. Each time a peer receives an event message, topics carried by the event message which the peer does not know but are related with subscribed topics are obtained in the peer. Thus, each peer learns and obtains new topics through receiving event messages. In the evaluation, we show the more number of topics each peer can initially subscribe, the fewer number of notifications are banned and the more number of forgotten topics are added to the subscription. However, the advantage obtained by initially including more number of topics decreases as the number of event messages exchanged among peers increases.","Title: Multi-Level Power Consumption Model And Energy-Aware Server Selection Algorithm\nYear: 2017\n\nAbstract: Electric power consumed by servers has to be reduced in a cluster in order to realise eco society. We take a macro-level approach to reducing the total electric energy consumption of servers to perform application processes. In this paper, we discuss a Multi-Level Power Consumption (MLPC) model of a server with a multi-thread CPU and a Multi-Level Computation (MLC) model. Based on the MLPC and the MLC models, we newly propose an energy-aware (EA) algorithm to select a server for each process requested by a client in a cluster to reduce the total electric energy consumption of the cluster while satisfying deadline requirements of the processes. We evaluate the EA algorithm and show that not only the total electric energy consumption of servers but also the average execution time of each process are reduced in the EA algorithm compared with the round-robin (RR) and random (RD) algorithms.","Title: Algorithms For Energy-Efficient Broadcasting Messages In Wireless Networks\nYear: 2018\n\nAbstract: In order to realize the cooperation of a group of multiple nodes, messages have to be reliably and efficiently delivered to all of them, according to a traditional broadcasting paradigm, by also reducing the electric energy consumed by each involved node. In this paper, we propose three types of energy-efficient broadcast algorithms, namely EEB (energy-efficient broadcast), EEB2 (modified EEB), and AEEB (augmented EEB) whose objective is reducing the total electric energy consumed by nodes. In the EEB algorithm, a wireless link to a farthest child node is truncated until there is no other child node which can forward messages to it in a more energy-efficient way. In the EEB2 algorithm, a link to a farthest child node is truncated if there is another child node which can forward the message to it. In the EEB and EEB2 algorithms, a child node is selected for each parent node. On the other hand, one parent node is selected among possible parent nodes of each child node, which is nearest to the child node in the AEEB algorithm. We evaluate the EEB, EEB2, and AEEB algorithms and show that the total electric energy consumed by nodes can be reduced in the AEEB algorithm.","Title: Visual CAPTCHA application in linguistic cryptography.\nYear: 2018\n\nAbstract: This paper presents an idea of linguistic cryptography and linguistic techniques for data analysis. The main aspects are using parts of divided information to reconstruct them. Linguistic techniques dedicated to cryptography, as well as secret splitting and sharing, are very useful to secure all information and all parts of them. Very important aspects of cryptographic algorithms are played by techniques of data division as well as data splitting and information sharing algorithms. Those methods allow the distributed data within a different selected group of secret trustees. In this paper, authors described algorithms of using those methods for linguistic data sharing techniques. In those methods, CAPTCHA analysis plays an important role. All secret parts of information can be written by using any parts of the selected CAPTCHA procedures.","Title: Cognitive Approaches for Medicine in Cloud Computing.\nYear: 2018\n\nAbstract: • We proposed a cognitive methods for data description. • Proposed a techniques for secure data in Cloud Computing. • Application of cognitive approaches for medicine was described.","Title: Concept of the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\nYear: 2017\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, the explanation about the scheme to manage the specific domain is performed. In this scheme, the scheme to manage the network group of plural organizations is expanded.","Title: Interference Aware Metric-Based Routing Protocol in Cognitive Radio Networks.\nYear: 2017\n\nAbstract: Cognitive radio networks (CRNs) are spectrum agile devices capable of changing their communication parameters based on their spectral environment. This capability can be exploited by designing dynamic spectrum access strategies that can utilize the unused spectrum vacated by the licensed users. In this paper, the problem of routing in Cognitive Radio Networks is investigated by exploiting the unoccupied spectrum called Spectrum Opportunities (SOP). An efficient Interference Aware Routing Protocol (IARP) is proposed which can be used to route the data packets between the unlicensed secondary users. The proposed IARP uses an interference aware routing metric (IR) that takes into account the interference in the spectral environment to determine good quality paths between two nodes. The performance of the IARP protocol is evaluated by simulating the CRN under different scenarios. The experimental results show the efficiency of the proposed routing protocol in delivering high throughput and packet delivery ratio with minimum network latency.","Title: An Energy Efficient Load Balancing Algorithm Based on the Active Time of Cores.\nYear: 2017\n\nAbstract: Server cluster systems are widely used to realize scalable and high performance computing systems with virtual machine technologies. A large amount of electric energy is consumed in a server cluster system since a server cluster system is composed of large number of servers and multiple servers consume electric energy to perform application processes on multiple virtual machines. In order to design and implement an energy-efficient server cluster system, it is necessary to realize energy-efficient load balancing algorithms. In this paper, the active time-based (ATB) algorithm is proposed to select a virtual machine for each request process so that the total electric energy of a server cluster to perform computation type application processes can be reduced. In the ATB algorithm, it is not necessary to collect a state of every process on every virtual machine to estimate the electric energy of each server. We evaluate the ATB algorithm in terms of the total electric energy of a server cluster compared with the energy consumption laxity based (ECLB) and basic round-robin (RR) algorithms.","Title: Performance Evaluation of WMNs by WMN-PSOSA Simulation System Considering Random Inertia Weight Method and Linearly Decreasing Vmax Method.\nYear: 2017\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the Performance of WMN-PSOSA by conducting computer simulations considering Random Inertia Weight Method (RIWM) and Linearly Decreasing Vmax Method (LDVM). The simulation results show that the LDVM has better performance than RIWM for this scenario.","Title: Comparison of Spray and Wait and Epidemic Protocols in Different DTN Scenarios.\nYear: 2017\n\nAbstract: In this paper, we evaluate the performance of Epidemic, Spray and Wait, and their versions with congestion control and Epidemic with TCP in two different set of simulations. In the first set of simulations, we evaluate the effect of network node density for map-based mobility model considering Tirana city map. In the second set of simulations, we compare the effect of mobility model on the network performance by comparing the results of map-based model with RWP mobility model. The performance evaluation metrics are: delivery ratio, hop count, average delay, average buffer occupancy. Simulations are conducted using NS3 simulator. The simulation results show that increase of node density increase also the delivery ratio. The performance using RWP is higher compared with the realistic scenarios because in the realistic scenario the nodes movement is more complex and opportunistic contacts are more rare. The usage of epidemic with TCP leads to high average delay in all scenarios because the need of sending ack packets to the source nodes.","Title: Hybrid Replication Schemes of Processes for Fault-Tolerance Systems in Energy-Efficient Server Clusters.\nYear: 2017\n\nAbstract: Application processes have to be not only fault-tolerantly but also energy-efficiently and performance-efficiently performed on servers in a cluster. The more number of replicas of a process are performed on servers, the more reliably and availably the process can be performed. However, the more electric energy is consumed by servers since the more number of servers work to perform the replicas. We make clear software components of replicas of a process. In this paper, we discuss new types of replica groups which are composed of different types of replicas with different software components. In the evaluation, we show the electric energy consumption of servers can be reduced in the replica groups compared with the traditional active and passive types of replication schemes.","Title: A Low-Energy Unicast Ad-Hoc Routing Protocol in Wireless Networks.\nYear: 2017\n\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently exchanged among neighboring nodes. In our previous studies, the reactive type ESU (Energy-Saving Unicast routing) and EAO (Energy-Aware One-to-one routing) protocols are proposed. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In this paper, we newly proposed an LEU (Low-Energy Unicast Ad-hoc routing) protocol to overcome the difficulties of the EAO protocol. Here, a neighbor node which has an uncovered neighbor node is selected as a prior node for each node to make a route. In the evaluation, we show the number of nodes in a source-to-destination route can be reduced and a route can be found even in shorter communication range in the LEU protocol compared with the EAO protocol.","Title: Classification of Cognitive Service Management Systems in Cloud Computing.\nYear: 2017\n\nAbstract: In this paper will be presented a new classification of cognitive systems dedicated to cloud service management. Especially, this classification will be described with application of cognitive aspects. Semantic description will be dedicated to service management application in the cloud. In particular will be presented the most important aspects of cognitive service management in the cloud and distributed systems. Services management in the cloud can be realized with application of secure semantic idea and cognitive service management solutions.","Title: A Simple Migration Algorithm of Virtual Machine in a Server Cluster.\nYear: 2017\n\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where virtual machines with application processes migrate to more energy-efficient servers. We newly propose an ISEAM2 algorithm to select a virtual machine on a host server to perform a process issued by an application and a guest server to which the virtual machine migrates so that the electric energy consumption of the servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and average execution time of processes can be reduced in the ISEAM2 algorithm.","Title: A Flexible Synchronization Protocol for Hidden Topics to Prevent Illegal Information Flow in P2PPS Systems.\nYear: 2017\n\nAbstract: We consider the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. Here, event messages on hidden topics which a peer can subscribe but a target peer cannot subscribe are notified to target peers. After an event message e(1) with hidden topics is notified, if a peer publishes another event message e(2), the event message e(2) may be related with the hidden topics. Hence, if the event message is notified to another peer which does not subscribe the hidden topics, illegal information flow occur. In this paper, we newly propose an FS-H (Flexible Synchronization for Hidden topics) protocol where a peer obtains hidden topics in the subscription if the hidden topics are related with the subscription topics. In the evaluation, the fewer number of notifications are banned in the FS-H protocol than the other protocols.","Title: Virtual Machine Migration Algorithms to Reduce Electric Energy Consumption of a Server Cluster.\nYear: 2018\n\nAbstract: In this paper, we discuss a virtual machine migration approach to reducing the electric energy consumption of servers. In our previous algorithms, one virtual machine migrates from a host server to a guest server. While the electric energy consumption of servers can be reduced by migrating some number b of processes, there might not be a virtual machine with the same number b of processes on a host server. In this paper, we propose an ISEAM2T algorithm where multiple virtual machines can migrate from a host server to a guest server. Here, multiple virtual machines on a host server are selected so that the total number of processes on the virtual machines can be more easily adjusted to the best number b of processes. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the proposed algorithm.","Title: Performance Analysis of Simulation System Based on Particle Swarm Optimization and Distributed Genetic Algorithm for WMNs Considering Different Distributions of Mesh Clients.\nYear: 2018\n\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), calledWMN-PSODGA. We analyze the performance of WMN-PSODGA by computer simulations considering different client distributions. Simulation results show that the WMN-PSODGA has good performance when the client distribution is Normal compared with the case of Exponential distribution.","Title: One-to-One Routing Protocols for Wireless Ad-Hoc Networks Considering the Electric Energy Consumption.\nYear: 2018\n\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently delivered to destination nodes by exchanging the messages among neighboring nodes. In our previous studies, the reactive type EAO, LEU, and IEAO protocols are proposed to unicast messages. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In the IEAO protocol, a route can be found even in short communication range. In the forwarding phase, a node p(i) does not necessarily receive an RQ messages which sent by a node p(j) whose level parameter is bigger than p(j) and keeps the information which is contained in the RQ messages. Here, by neglecting superfluous RQ messages, the electric energy consumption of the forwarding phase can be reduced. In this paper, we propose an IEAO2 protocol by improving the IEAO protocol so that the electric energy consumption is reduced in the forwarding phase. In the evaluation, we show the information which each node keeps can be reduced in the IEAO2 protocol compared with other protocols.","Title: An Integrated System Considering WLAN and DTN for Improving Network Performance: Evaluation for Different Scenarios and Parameters.\nYear: 2018\n\nAbstract: In this paper, we integrate a Wireless Local Area Network (WLAN) with a Delay Tolerant Network (DTN) to improve the network performance when the network is congested or communication link problems occur. We evaluate the performance under different scenarios for three routing protocols. Simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The simulation results shows that with the increase of the simulation time DTN hosts are in movement for longer time and the probability of the DTN hosts to meet and exchange the data is increased. The usage of DTN improves the performance of the network by sending information with high delivery probability.","Title: Eco Migration Algorithms of Processes with Virtual Machines in a Server Cluster.\nYear: 2018\n\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where a virtual machine with application processes migrates to a more energy-efficient server. We newly propose an ISEAM2 algorithm to select a pair of a virtual machine on a host server to perform a process issued by an application and a guest server to which the virtual machine migrates so that the electric energy consumption of the host and guest servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the ISEAM2 algorithm.","Title: Malicious Information Flow in P2PPS Systems.\nYear: 2018\n\nAbstract: We consider the peer-to-peer (P2P) type of topic-based publish/ subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. An event message e(1) may carry information of another event message e(2) causally preceding e(1), which are denoted by topics. If a peer receiving e(1) is not allowed to subscribe the topics, illegal information flow to the peer occur. In our previous studies, the subscription-based synchronization (SBS), topic-based synchronization (TBS), and flexible synchronization for hidden topics (FS-H) protocols are proposed to prevent illegal information flow. In this paper, we newly consider malicious information flow among peers where a source peer does not give related topics or gives unrelated topics to event messages. If a source peer pi publishes an event message e without including some related topic or with including some unrelated topic, the peer pi is malicious. In this paper, we newly define types of malicious information flow among peers based on a set of topics which every peer can publish and subscribe.","Title: Service Management Protocols in Cloud Computing.\nYear: 2018\n\nAbstract: In this paper will be presented a description of service management protocols for Cloud infrastructure. Especially, presented solutions will be dedicated to Cloud and Fog Computing. The main idea will be described with application of semantic aspects, dedicated to service management application. Services management protocols in the cloud and in the fog can be realized with application of secure and strategic methods.","Title: Performance Evaluation of WMN-PSOSA Considering Four Different Replacement Methods.\nYear: 2018\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering four different replacement methods. The simulation results show that LDIWM have better performance than CM, RIWM and LDVM replacement methods.","Title: Design and Implementation of a Hybrid Intelligent System Based on Particle Swarm Optimization and Distributed Genetic Algorithm.\nYear: 2018\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We evaluate WMN-PSODGA by computer simulations. The simulation results show that the WMN-PSODGA has good performance when the number of GA islands is 64.","Title: Application of Fuzzy Logic for Improving Human Sleeping Conditions in an Ambient Intelligence Testbed.\nYear: 2018\n\nAbstract: Ambient Intelligence (AmI) deals with a new world of ubiquitous computing devices, where physical environments interact intelligently and unobtrusively with people. AmI environments can be diverse, such as homes, offices, meeting rooms, schools, hospitals, control centers, vehicles, tourist attractions, stores, sports facilities, and music devices. In our previous work, we presented the implementation and evaluation of actor node for AmI testbed. In this paper, we introduce the implementation of the AmI testbed. We present the simulation results of the proposed Fuzzy-based Sleeping Condition System (FSCS) considering four parameters: room lighting, humidity, temperature and noise. The simulation results show that different parameters have different effects on human sleeping condition.","Title: Improved Energy-Efficient Quorum Selection Algorithm by Omitting Meaningless Methods.\nYear: 2018\n\nAbstract: Distributed applications are composed of multiple objects and each object is replicated in order to increase reliability, availability, and performance. On the other hand, the larger amount of electric energy is consumed in a system since multiple replicas of each object are manipulated on multiple servers. In our previous studies, the energy efficient quorum selection (EEQS) algorithm is proposed to construct a quorum for each method in the quorum based locking protocol so that the total electric energy of servers to perform methods can be reduced. In this paper, the improved energy efficient quorum selection (IEEQS) algorithm is proposed to furthermore reduce the total electric energy of servers by omitting meaningless methods. Evaluation results show the total electric energy of servers, the average execution time of each transaction, and the number of aborted transactions can be reduced in the IEEQS algorithm than the EEQS algorithm.","Title: Influence of Management and Sharing Protocols for Decision Making Processes in Cloud Computing.\nYear: 2018\n\nAbstract: In this paper will be evaluated influence of proposed sharing technologies for efficiency of decision making procedures in particular sectors or companies. Especially, such evaluation will be done for Cloud and Fog based procedures and services. Presented research justified the great importance of proper selection of efficient management services for particular task or distributed operations. Especially, presented solutions will be dedicated to Cloud and Fog Computing. The main idea will be describe with application of semantic aspects, dedicated to service management application. Services management protocols in the cloud and the fog can be realized with application of secure important and strategic idea.","Title: A Tree-Based Model of Energy-Efficient Fog Computing Systems in IoT.\nYear: 2018\n\nAbstract: A huge number and various types of devices like sensors and actuators are interconnected with clouds of servers in the IoT (Internet of Things). Here, a large volume of data created by sensors have to be efficiently transmitted and processed and actions have to be efficiently delivered to actuators at an opportune time. In order to reduce the delay time and increase the performance, data and processing are distributed to not only servers but also fog nodes in fog computing systems. On the other hand, the total electric energy consumed by fog nodes increases since a huge number of fog nodes are interconnected. In this paper, we newly propose a tree-based fog computing model to deploy processes and data to fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the tree-based model is smaller than the cloud model where processes and data are centralized.","Title: Performance Evaluation of WMN-PSOSA Considering Exponential and Weibull Distributions.\nYear: 2018\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, calledWMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering Exponential and Weibull distributions. Simulation results show that WMN-PSOSA performs better for Weibull distribution compared with the case of Exponential distribution.","Title: Energy-Efficient Process Replication by Forcing Meaningless Replicas to Terminate in Virtual Machine Environment.\nYear: 2018\n\nAbstract: Server cluster systems equipped with virtual machines are widely used to provide various types of reliable application services. Especially, multiple replicas of each application process can be redundantly performed on multiple virtual machines to realize reliable application services. On the other hand, a large amount of electric energy is consumed in a server cluster since multiple replicas of each application process are performed on multiple virtual machines. In this paper, the improved redundant energy consumption laxity based (IRECLB) algorithm is newly proposed to reduce the total electric energy consumption of a server cluster for redundantly performing each application process by forcing meaningless replicas to terminate. We evaluate the IRECLB algorithm in terms of the total electric energy consumption of a server cluster and the average response time of each process compared with the redundant energy consumption laxity based (RECLB) algorithm previously proposed.","Title: An Eco IDMMV Migration Algorithm of Dynamic Virtual Machines in a Server Cluster.\nYear: 2018\n\nAbstract: Processes on virtual machines can migrate from a host server to a guest server without suspending the processes by migrating the virtual machines. In our previous studies, the total electric energy consumed by servers and the average execution time of processes are shown to be reduced by migrating virtual machine to a more energy-efficient server. In this paper, we propose a DMMV2 (Dynamic Migration of Multiple Virtual machines 2) algorithm where multiple virtual machines migrate among servers. In the evaluation, we show not only the total electric energy consumption and total active time of servers but also the average execution time of processes can be reduced in the DMMV2 algorithm compared with other algorithms.","Title: Unicast Routing Protocols to Reduce Electric Energy Consumption in Wireless Ad-Hoc Networks.\nYear: 2018\n\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently exchanged among neighboring nodes. In our previous studies, the reactive type EAO (Energy-Aware One-to-one routing) and LEU (Low-Energy Unicast Ad-hoc routing) protocols are proposed to unicast messages to the destination node. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In this paper, we newly proposed an IEAO (Improved Energy-Aware One-to-one routing) protocol to overcome the difficulties of the EAO protocol. Here, after a shortest route is found to the destination node, a more energy-efficient prior node is found in nearest neighbor of each node starting from the destination node. In this paper, a neighbor node which has an uncovered neighbor node is selected as a prior node for each node to make a route. In the evaluation, we show the number of nodes in a source-to-destination route can be reduced and a route can be found even in shorter communication range in the IEAO protocol compared with the LEU and EAO protocols.","Title: A Simple Algorithm to Select Energy-Efficient Servers for Storage and Computation Processes.\nYear: 2018\n\nAbstract: In application processes like Web and databases, files and databases are manipulated on servers. Thus, both CPU and storage resources are used to perform application processes. In this paper, we propose a computation model to give the expected termination time of each application process. Here, computation operations and storage operations of a process are integrated into virtual computation steps. Then, we propose an SGEAG (Simple Globally-Energy-Aware for General processes) algorithm to select a server to perform a new process issued by a client, which is expected to consume the minimum electric energy to perform not only the new process but also every current process. In the evaluation, we show the electric energy consumed by servers and the average execution time of processes can be more reduced in the SGEAG algorithm than the other algorithms.","Title: An Energy-Efficient Model of Fog and Device Nodes in IoT.\nYear: 2018\n\nAbstract: Various types and huge number of devices like sensors and actuators are interconnected with clouds of servers in IoT (Internet of Things). Here, a large volume of data including multimedia data like image created by sensors are transmitted to servers in clouds through networks. Processes in servers decide on actions and send the actions to actuators under time constraints like realtime one. However, huge volume of data are transmitted in networks and servers are heavily loaded. An intermediate layer named fog layer is introduced between clouds and devices in IoT to overcome the difficulties. Processing to be done and data to be stored in servers are distributed to fog nodes while centralized on servers in clouds in traditional cloud computing systems. In this paper, we newly propose a linear IoT model to deploy processes and data to devices, fog nodes, and servers in IoT so that the total electric energy consumption of nodes can be reduced. We show the total electric energy of the IoT model is smaller than the cloud model in the evaluation.","Title: Concept Of User Authentication Method For The Cloud Type Virtual Policy Based Network Management Scheme For The Specific Domain\nYear: 2018\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations as a third step, concept of user authentication method applied for this scheme is expanded and described.","Title: Design And Implementation Of A Hybrid Intelligent System Based On Particle Swarm Optimization, Hill Climbing And Distributed Genetic Algorithm For Node Placement Problem In Wmns: A Comparison Study\nYear: 2018\n\nAbstract: The Wireless Mesh Networks (WMNs) have low cost and high speed wireless Internet connectivity, therefore they are becoming an important networking infrastructure. In our previous work, we implemented a hybrid intelligent system based on Particle Swarm Optimization (PSO) and Hill Climbing (HC), called WMN-PSOHC, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a new hybrid simulation system based on PSOHC and distributed GA (DGA), called WMN-PSOHC-DGA. We evaluate WMN-PSOHC-DGA system by computer simulations. The simulation results show that the WMN-PSOHC-DGA system has a better performance compared with WMN-PSODGA.","Title: Performance Evaluation Of Wmn-Psodga System For Node Placement Problem In Wmns Considering Four Different Crossover Methods\nYear: 2018\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We evaluate WMN-PSODGA system by computer simulations. The simulation results show that the WMN-PSODGA system has a good performance for SPX crossover method compared with other crossover methods.","Title: A Protocol to Prevent Malicious Information Flow in P2PPS Systems\nYear: 2018\n\nAbstract: In the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer process (peer) can publish and subscribe event messages which are characterized by topics with no centralized coordinator. A peer pj publishes an event message ej after receiving an event message ei, i.e. ei causally precedes ej. Here, the event message ej may carry information of the event message ei. If a peer pk receiving ej is not allowed to subscribe the topics of ei, the peer pk illegally obtains the information by receiving ej. In our previous studies, the SBS, TBS, and FS-H protocols are proposed to prevent illegal information flow. In addition, if a source peer pi publishes an event message e without giving related topics or with giving unrelated topics, a destination peer pj may misunderstand the meaning of the event message e. Here, malicious information flow occurs. In this paper, we newly propose a TBSM (topic-based synchronization to prevent malicious information flow) protocol. Here, event messages which may cause malicious information flow are banned. In the evaluation, we show the number of event messages banned in the TBSM protocol is larger than the TBS protocol since the number of event messages which are just malicious is larger than just illegal.","Title: Simple Models of Processes Migration with Virtual Machines in a Cluster of Servers\nYear: 2018\n\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption of servers where a virtual machine with application processes migrates to a more energy-efficient server. In this paper, we consider a homogeneous cluster. We newly propose an ISEAM2H algorithm. Here, a virtual machine on a host server is selected to perform a process issued by an application and a guest server to which a virtual machine migrates is found so that the total electric energy consumption of servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the ISEAM2H algorithm.","Title: Cognitive Systems For Service Management In Cloud Computing\nYear: 2018\n\nAbstract: This paper presents topic of cognitive systems dedicated to management processes. In this paper will be described the cryptographic techniques dedicated to sharing processes with cognitive interpretation stages. Also, safety analysis of these methods will be described. Such algorithms will be presented especially in Cloud Computing context. This solution allow protecting confidential information, and performing secure operation for different kinds of information.","Title: An Eco Migration Algorithm of Virtual Machines in a Server Cluster\nYear: 2018\n\nAbstract: Processes on virtual machines can migrate from a host server to a guest server by migrating the virtual machines. In this paper, we propose a DMMV (Dynamic Migration of Multiple Virtual machines) algorithm where virtual machines migrate from a host server to a more energy-efficient guest server. Here, virtual machines are dynamically suspended and resumed depending on the number of processes. In addition, one or more than one virtual machine is selected to migrate from a host server to a guest server. The number of virtual machines to migrate is decided so as to minimize the electric energy consumption of the host and guest servers. In the evaluation, we show not only the total electric energy consumption and active time of servers but also the average execution time of processes can be reduced in the DMMV algorithm compared with other algorithms.","Title: An Energy-Efficient Process Replication Algorithm Based on the Active Time of Cores\nYear: 2018\n\nAbstract: Server cluster systems equipped with virtual machines are widely used to realize fault-tolerant systems. Application processes are redundantly performed on multiple virtual machines to realize reliable distributed applications. However, a large amount of electric energy is consumed in a server cluster system since multiple replicas of each application process are redundantly performed on multiple virtual machines. In this paper, the redundant active time-based (RATB) algorithm is proposed to select multiple virtual machines for each application process so that the total electric energy of a server cluster to redundantly perform each application process can be reduced. In the RATB algorithm, it is not necessary for a load balancer to communicate with every virtual machine to estimate the electric energy of each server. Hence, the overhead of a load balancer to estimate the electric energy of each server and forward request processes can be reduced. We evaluate the RATB algorithm in terms of the total electric energy of a server cluster and the average response time of each process compared with the redundant energy consumption laxity based (RECLB) algorithm.","Title: Concept of Policy Information Decision Method in the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain\nYear: 2018\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, the concept of policy information decision method applied for this scheme are described.","Title: A flexible read-write abortion protocol with role safety concept to prevent illegal information flow.\nYear: 2018\n\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally reads data in an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the FRWA-R (flexible read-write-abortion with role sensitivity) and FRWA-O (object sensitivity) protocols are proposed to prevent illegal information flow. Here, a transaction aborts with some probability once illegally reading data in an object. The abortion probability depends on the sensitivity of roles which the transaction holds and objects in which the transaction illegally reads data. The role sensitivity and object sensitivity show how many transactions which hold the role and illegally read data in the object abort after illegally reading data in the object, respectively. Here, the sensitivity just monotonically increases each time a transaction aborts. In this paper, we propose a new safety concept of a role and an FRWA-RS (FRWA with role safety) protocol. Here, the safety of a role increases and decreases each time a transaction holding the role commits and aborts by issuing an illegal read operation, respectively. A transaction with safer roles aborts with smaller probability. In the evaluation, we show fewer and more numbers of transactions abort in the FRWA-RS protocol than the RWA protocol and than the WA protocol, respectively, and transactions are more efficiently performed than the WA protocol.","Title: Dynamic Migration Of Virtual Machines To Reduce Energy Consumption In A Cluster\nYear: 2018\n\nAbstract: Virtual machines are widely used to support applications with virtual service in server clusters. Here, a virtual machine can migrate from a host server to a guest server. In this paper, we consider a cluster where virtual machines are dynamically created and dropped depending on the number of processes. We propose a dynamic virtual machine migration (DVMM) algorithm to reduce the total electric energy consumption of servers. If an application issues a process to a cluster, the most energy-efficient host server is first selected and then the process is performed on a virtual machine of the server. Then, a virtual machine migrates from a host server to a guest server so that total electric energy consumption of servers can be reduced. In the evaluation, we show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the DVMM algorithm.","Title: The Improved Transmission Energy Consumption Laxity Based (ITECLB) Algorithm for Virtual Machine Environments.\nYear: 2018\n\nAbstract: Various types of distributed applications are realized in server cluster systems equipped with virtual machines like cloud computing systems. On the other hand, a server cluster system consumes a large amount of electric energy since a server cluster system is composed of large number of servers and each server consumes the large electric energy to perform application processes on multiple virtual machines. In this paper, the improved transmission energy consumption laxity based (ITECLB) algorithm is proposed to allocate communication processes to virtual machines in a server cluster so that the total electric energy consumption of a server cluster and the average transmission time of each communication process can be reduced. We evaluate the ITECLB algorithm in terms of the total electric energy consumption of a server cluster and the average transmission time of each process compared with the transmission energy consumption laxity based (TECLB) algorithm.","Title: A Hybrid Simulation System Based on Particle Swarm Optimization and Distributed Genetic Algorithm for WMNs - Performance Evaluation Considering Normal and Uniform Distribution of Mesh Clients.\nYear: 2018\n\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We analyze the performance of WMNs using WMN-PSODGA simulation system considering Normal and Uniform client distributions. Simulation results show that the WMN-PSODGA has good performance for Normal distribution compared with the case of Uniform distribution.","Title: An Energy-Efficient Dynamic Live Migration of Multiple Virtual Machines.\nYear: 2018\n\nAbstract: In this paper, we propose an algorithm to migrate virtual machines to reduce the total electric energy consumption of servers. Here, virtual machines are dynamically resumed and suspended so that the number of processes on each virtual machine can be kept fewer. In addition, multiple virtual machines migrate from a host server to a more energy-efficient guest server. In our previous studies, time to migrate virtual machines is assumed to be zero. The more often a virtual machine migrates, the longer time it takes to perform processes on the virtual machine. We propose a model to estimate the electric energy consumption of servers by considering the migration time of each virtual machine. By using the model, virtual machines to migrate and to perform processes are selected so that the total electric energy consumption can be reduced. In the evaluation, we show the total electric energy consumption of servers can be reduced compared with other algorithms.","Title: Object-Based Information Flow Control Model in P2PPS Systems.\nYear: 2018\n\nAbstract: In the P2PPS (P2P (peer-to-peer) type of topic-based PS (publish/subscribe)) model, each peer process (peer) publishes and subscribes event messages which are characterized by topics with no centralized coordinator. An illegal information flow occurs if an event message e(j) published by a peer p(j) carries information on some topics into the peer p(i), which the target peer p(i) is not allowed to subscribe. In our previous studies, the SBS, TBS, and FS-H protocols are proposed to prevent illegal information flow among peers by banning event messages. In the protocols, the number of topics kept in every peer monotonically increases. Hence, most of the event messages are banned. In this paper, we newly consider the P2PPSO (P2PPS with object concept) model where the number of topics kept in every peer increases and decreases each time objects obtained by every peer are updated. In order to prevent illegal information flow from occurring in the P2PPSO system, we newly propose a TOBS (topics of objects-based synchronization) and TSOBS (topics and states of objects-based synchronization) protocols. In the TOBS protocol, it is simpler to detect illegal information flow than the TSOBS protocol. On the other hand, the fewer number of event messages are banned in the TSOBS protocol than the TOBS protocol.","Title: Consideration of Policy Information Decision Processes in the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\nYear: 2018\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, the policy information decision processes applied for this scheme are considered and described.","Title: Innovative Protocols for Data Sharing and Cyber Systems Security.\nYear: 2018\n\nAbstract: In this paper will be presented new classes of cryptographic secret sharing procedures dedicated for secure information division and transmission. In particular will be presented two classes of protocols, which allow to share information with application of grammar solutions, as well as personal or behavioral parameters. Some possible application of such technologies will also be presented especially with relation to secure data or services management in distributed structures or Cloud environment.","Title: Evaluation of an Energy-Efficient Tree-Based Model of Fog Computing.\nYear: 2018\n\nAbstract: A huge number of devices like sensors are interconnected in the IoT (Internet of Things). In the cloud computing model, processes and data are centralized in a cloud. Here, networks are congested and servers are overloaded due to heavy traffic from sensors. In order to reduce the delay time and increase the performance, data and processes to handle the data are distributed to not only servers but also fog nodes in fog computing models. On the other hand, the total electric energy consumed by fog nodes increases to process a sensor data. In this paper, we newly propose a tree-based fog computing model to distribute processes and data to servers and fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the tree-based model is smaller than the cloud computing model.","Title: A Causally Precedent Relation Among Messages in Topic-Based Publish/Subscribe Systems.\nYear: 2018\n\nAbstract: Event-driven publish/subscribe (PS) systems are widely used in various types of applications. In this paper, we consider a peer-to-peer (P2P) model of a topic-based PS system which is composed of peer processes (peers) with no centralized coordinator. Here, each peer publishes a message with publication topics while receiving messages whose publication topics are in the subscription topics of the peer. Each peer has to deliver every pair of messages related with respect to topics in the causal order of publication events. In this paper, a message is considered to carry objects whose meanings are denoted by topics. Based on the meanings of objects, we define an object-based-causally (OBC) precedent relation among messages. Based on the OBC precedent relation, we newly propose a protocol to topic-based-causally (TBC) deliver messages to peers. Here, each peer causally delivers event messages which are related with respect to topics. If a message m(1) OBC-precedes a message m2, the message m1 TBC-precedes m(2).","Title: Performance Evaluation of Energy Consumption for Different DTN Routing Protocols.\nYear: 2018\n\nAbstract: In this paper, we evaluate the energy consumption of different routing protocols in a Delay Tolerant Network (DTN). Seven groups with three stationary sensor nodes for each group sense the temperature, humidity and wind speed and send these data to a stationary destination node that collects them for statistical and data analysis purposes. The opportunistic contacts will exchange the sensed data to different relay nodes that are pedestrians and cyclist equipped with smart devices moving in Tirana city roads, until the destination node is reached. For simulations we use the Opportunistic Network Environment (ONE) simulator. Nodes in this DTN are energy constrained and play an important role in the success of delivering messages. When the energy of a node is low chance to deliver messages across the network. In this work, we evaluate and compare the performance of different routing protocols in order to find the energy-efficient routing protocol to be used for message transmission for our DTN application. We evaluate the nodes average remaining energy, the number of dead nodes, delivery probability and overhead ratio for different routing protocols.","Title: Performance Evaluation of WMNs by WMN-PSOSA Simulation System Considering Constriction and Linearly Decreasing Vmax Methods.\nYear: 2017\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem inWMNs, calledWMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, calledWMN-PSOSA. We evaluate the performace of WMN-PSOSA by conducting computer simulations considering Constriction Method (CM) and Linearly Decreasing Vmax Method (LDVM). The simulation results show that the LDVM has better performace than CM for this scenario.","Title: Routing in a DTN: Performance Evaluation for Random Waypoint and Steady State Random Waypoint Using NS3 Simulator.\nYear: 2017\n\nAbstract: In this paper we evaluate the performance of Epidemic, Spray and Wait and their versions with congestion control and Epidemic with TCP for Random Waypoint (RWP) and Steady State Random Waypoint (SSRWP) mobility models. For performance evaluation, we used delivery ratio, hop count, average delay and average buffer occupancy metrics. Simulations are conducted using NS3 simulator. The simulation results show that the network performance is better for SSRWP mobility model.","Title: A Dynamic Model For Energy-Efficiently Migrating A Group Of Virtual Machines From A Host Server To A Guest Server\nYear: 2018\n\nAbstract: In this paper, we newly propose a dynamic migration of a group of v virtual machines [DMG(v)] algorithm to reduce the total electric energy consumption of servers in a cluster. Here, virtual machines are dynamically resumed and suspended so that the number of processes on each virtual machine can be kept fewer. In addition, a group of v (v >= 1) virtual machines migrate from a host server to a guest server so that the total electric energy consumed by the servers can be reduced. In our previous studies, time to migrate each virtual machine is assumed to be zero. In reality, there is migration time every process is suspended on a virtual machine migrating even in the live manner. Hence, the more often a virtual machine migrates, the longer time it takes to perform processes on the virtual machine. We propose a model to estimate electric energy to be consumed by servers through considering the migration time of each virtual machine. By using the estimation model, we can decide on which virtual machines on a host server to which guest server so that the total electric energy consumption of the host and guest servers can be reduced. In the evaluation, we show the total electric energy consumption of servers can be reduced by the DMG(v) algorithm compared with other algorithms.","Title: Model of Mobile Objects\nYear: 1996\n\nAbstract: Abstract. Distributed systems are composed of multiple objects. Ob-jects support abstract operations and are distributed in not only xed stations but also mobile ones. While the object is moving from one lo-cation to others, the quality of service (QoS) supported by the object is changed. We model the movement of the object as changes of QoS sup-ported by the object. W e discuss how to support users with QoS required while QoS of the object is being changed. W e present the migration and replication methods as a general framework to treat the disconnected operations. In addition, we present an optimistic concurrency control to maintain the mutual consistency among the replicas.","Title: Concurrent Execution of Prolog Transaction\nYear: 1987\n\nAbstract: Information systems are composed of multiple heterogeneous database systems and workstations interconnected by communication networks. Users want to manipulate data in multiple database systems in a common form. In our system, database systems are viewed to be fact base systems (FBSs), which provide sets of Prolog ground unit clauses, and retrieval and update operations on them. Transactions composed of multiple update operations on facts are written as Prolog rule clauses. In the Prolog system, atoms in a goal clause are selected from left to right. This means read/write operations on facts are sequentially executed. In this paper, we try to execute the transaction in parallel by multiple FBSs. In the sequence of atoms in the Prolog transaction, we define two types of meaningful sequences, i.e. conflict and flow ones. In this paper, we present how to decompose transactions into subtransactions, each of which is locally executed by one FBS, so as to preserve the meaningful sequences in the transaction. Also, we show that any parallel execution of the subtransactions is free of deadlock on send-receive relations.","Title: Comparison Analysis by WMN-GA Simulation System for Different WMN Architectures, Distributions and Routing Protocols Considering TCP.\nYear: 2016\n\nAbstract: In this paper, we evaluate the performance of two WMN architectures considering Packet Delivery Ratio (PDR), throughput, delay and energy metrics. For simulations, we used ns-3 and Transmission Control Protocol (TCP). We compare the performance for Hybrid Wireless Mesh Protocol (HWMP) and Optimized Link State Routing (OLSR) for normal and uniform distributions of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the PDR for both distributions and architectures is almost the same, but the PDR of HWMP is a little bit better than OLSR. the throughput is better for normal distribution and I/B WMN architecture in case of HWMP. However, for OLSR and normal distribution, the throughput of Hybrid WMN is a little bit higher than I/B WMN. For both distributions the delay of both architectures is better for HWMP compared with OLSR. For both WMN architectures and routing protocols for normal and uniform distributions, respectively. For normal distribution, the energy decreases sharply, because of the high density of nodes, thus the nodes spend more energy. So, the uniform distribution has better performance compared with normal distribution considering the energy parameter.","Title: An Energy-Efficient Process Replication Algorithm in Virtual Machine Environments.\nYear: 2016\n\nAbstract: Server cluster systems are widely used to realize fault-tolerant, scalable, and high performance application services with virtual machine technologies. In order to provide reliable application services, multiple replicas of each application process can be redundantly performed on multiple virtual machines. On the other hand, a server cluster system consumes a large amount of electric energy since multiple replicas of each application process are performed on multiple virtual machines. It is critical to discuss how to realize not only reliable but also energy-efficient server cluster systems. In this paper, we propose the redundant energy consumption laxity based (RECLB) algorithm to select multiple virtual machines for redundantly performing each application process in presence of server faults so that the total energy consumption of a server cluster and the average computation time of each process can be reduced. We evaluate the RECLB algorithm in terms of the total energy consumption of a server cluster and the average computation time of each process compared with the basic round-robin (RR) algorithm.","Title: A Probabilistic Encounter and Distance-based Routing Protocol for Opportunistic Networks.\nYear: 2016\n\nAbstract: An Opportunistic Network (OppNet) is one of the latest domain of wireless communication where information is transferred from the source to the destination without any infrastructure, internet connectivity and any predefined network topology. The mobile nodes participating in the network contribute in establishing a connectivity between the nodes to transmit the information from the source to the destination using a store-carry and forward mechanism. The nodes store the information in their in-built buffer until a suitable forwarder is available within their wi-fi/bluetooth transmission range. Designing a routing protocol in OppNet is thus a challenging task. This paper proposes a Probabilistic Encounter and Distance-based Routing Protocol (P-EDR) for Opportunistic Networks, which is designed as a combination the ProPHet and the Encounter and Distance-based Routing (EDR) protocols. Simulation results are presented, showing that P-EDR outperforms the EDR, History-based Prediction for Routing (HBPR) and ProPHet routing protocols in terms of message delivery probability, messages overhead ratio and number of messages dropped.","Title: An energy-aware load balancing algorithm to perform computation type application processes in a cluster of servers.\nYear: 2017\n\nAbstract: A cluster of servers is getting scalable and widely used in various types of applications. It is critical to reduce the electric energy consumed by servers in a cluster to realise eco society. In this paper, we newly propose an improved delay time based IDTB algorithm to reduce the total electric energy consumption of a cluster and to more efficiently utilise the computation resources for performing application processes in a cluster. In the IDTB algorithm, a load balancer estimates the state of each server just by using responses from processes and without additionally communicating with servers to collect states of the servers. We evaluate the IDTB algorithm compared with the basic round-robin RR, improved power consumption laxity based IPCLB, and delay time based DTB algorithms. We show the total electric energy consumption of a cluster and response time of each process can be reduced in the IDTB algorithm.","Title: Hybrid Replication Schemes of Processes in Energy-Efficient Server Clusters.\nYear: 2017\n\nAbstract: In order to fault-tolerantly perform an application process in a server cluster, the process is replicated on multiple servers. Even if some replicas of the process is faulty, e.g. due to stop-fault of the host server, the process can be successfully performed as long as some number of replicas are operational. The more number of replicas of a process are performed, the more reliably and availably the process can be performed but the more electric energy is consumed. In this paper, we make clear what software components each replica of a process includes. We newly propose new replication schemes which are composed of a primary replica and more types of secondary replicas so that the total electric energy consumption can be reduced while the reliability and availability of each process can be increased. In the evaluation, we show the electric energy consumption of servers can be reduced in the replication schemes compared with the traditional active and passive replication schemes.","Title: Implementation of an intelligent hybrid simulation systems for WMNs based on particle swarm optimization and simulated annealing: performance evaluation for different replacement methods\nYear: 2019\n\nAbstract: Wireless mesh networks (WMNs) have many advantages such as low-cost and increased high- speed wireless Internet connectivity; therefore, WMNs are becoming an important networking infrastructure. In our previous work, we implemented a particle swarm optimization (PSO)-based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on simulated annealing (SA) called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering four different replacement methods. The simulation results show that the rational decrement of Vmax method and linearly decreasing inertia weight method have better performance compared with constriction method and random inertia weight method.","Title: An Information Flow Control Model In A Topic-Based Publish/Subscribe System\nYear: 2018\n\nAbstract: A publish/subscribe (PS) model is an event-driven model of a distributed system. In traditional PS systems, each peer (process) can either publish or subscribe events. In this paper, we consider a peer-to-peer (P2P) type of topic-based PS model where each peer can both publish and subscribe events. In this paper, we newly propose a topic-based access control (TBAC) model for topic-based PS systems. Here, an access right is a pair < t, op > of a topic t and a publish or subscribe operation op. A peer is allowed to publish an event message with publication topics and subscribe interesting topics only if the publication and subscription access rights are granted to the peer, respectively. An event message e is delivered to a peer p(i) if the publication of e and subscription of pi include some common topic. If a peer pi publishes an event message e2 after receiving an event message e1, the event message e2 may bring some information of the event message e1. If a target peer p(j) is not allowed to subscribe at least one topic which is related with the event message e1, information in the peer pi illegally flows to the target peer pj. We newly propose a subscription-based synchronization (SBS) protocol to prevent illegal information flow. Here, an event message is banned by a target peer if the event message implies illegal information flow. However, event messages may be unnecessarily banned by a peer even if no illegal information flow to the peer occurs. In the evaluation, we show the number of event messages unnecessarily banned in the SBS protocol.","Title: Simple Algorithms For Selecting An Energy-Efficient Server In A Cluster Of Servers\nYear: 2018\n\nAbstract: Electric energy consumed by computers, especially servers in scalable clusters has to be reduced to realise eco society. In this paper, we first propose a multi-level power consumption (MLPCM) model which gives how much electric power a server consumes to perform application processes. We also propose an multi-level computation (MLCM) model which shows the expected execution time of an application process performed on a server. By using the MLPCM and MLCM models, we propose a pair of simple locally energy-aware (SLEA) and simple globally energy-aware (SGEA) algorithms to select a host server to perform an application process issued by a client. In the SLEA algorithm, a host server is selected, which is expected to consume the minimum electric energy to perform the process. In the SGEA algorithm, a host server is selected, where the total expected electric energy consumption of not only the host server but also the other servers is minimum. In the evaluation, we show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the SGEA algorithm compared with other algorithms.","Title: Energy consumption laxity-based quorum selection for distributed object-based systems\nYear: 2020\n\nAbstract: In object based systems, an object is an unit of computation resource. Distributed applications are composed of multiple objects. Objects in an application are replicated to multiple servers in order to increase reliability, availability, and performance. On the other hand, the large amount of electric energy is consumed in a system compared with non-replication systems since multiple replicas of each object are manipulated on multiple servers. In this paper, the energy consumption laxity-based quorum selection (ECLBQS) algorithm is proposed to construct a quorum for each method issued by a transaction so that the total electric energy consumption of servers to perform methods can be reduced in the quorum based locking protocol. The total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted transactions are shown to be more reduced in the ECLBQS algorithm than the random algorithm in evaluation.","Title: Evaluation of a Protocol to Prevent Malicious Information Flow in P2PPS Systems.\nYear: 2018\n\nAbstract: In the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer process (peer) can publish and subscribe event messages which are characterized by topics with no centralized coordinator. A peer p(j) publishes an event message e(j) after receiving an event message e(i), i.e. ei causally precedes ej. Here, the event message e(j) may carry information of the event message e(i). If a peer pk receives ej but is not allowed to subscribe the topics of e(i), the peer p(k) illegally obtains the information of e(i) via e(j). In addition, if a source peer pi publishes an event message e without related topics or with unrelated topics, a destination peer p(j) may misunderstand the meanings of the event message e, i.e. the event message e is maliciously received by the peer p(j). In our previous studies, the SBS, TBS, FS-H protocols and the TBSM protocol are proposed to ban illegal and malicious event messages, respectively. In this paper, we evaluate the TBSM protocol in terms of the numbers of illegal and malicious types of event messages. In the evaluation, we show the ratio of the number of event messages banned decreases as the numbers of topics in a system increases.","Title: An energy-efficient model for fog computing in the Internet of Things (IoT)\nYear: 2018\n\nAbstract: A huge number of devices like sensors in addition to computers are interconnected in the IoT (Internet of Things). In the cloud computing model, sensor data is transmitted to servers in networks and processed on the servers in a cloud. Here, networks are congested and servers are overloaded due to heavy traffic from sensors. In order to reduce the delay time and network traffic and increase the performance of the system, data and processes are distributed to not only servers in a cloud but also fog nodes in fog computing models. While the traffic of servers in a cloud can be reduced, the total electric energy consumed by fog nodes increases to process sensor data. In this paper, we newly propose a tree-based fog computing (TBFC) model to distribute processes and data to servers and fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the TBFC model is smaller than the cloud computing model.","Title: A Virtual Machine Migration for Storage Processes\nYear: 2018\n\nAbstract: Virtual machines are widely used to support applications with virtual computation service of computer resources like CPUs and storages in a cluster of servers. Application processes on a virtual machine can take usage of not only CPUs but also storage resources like files and databases independently of heterogeneity and location of each host server. In addition, virtual machines can migrate from a host server to a guest server in the live manner. In this paper, we consider storage processes which read and write data in files of storages like HDD. Through experiments, we make clear the execution time of a storage process on a virtual machine while the virtual machine is migrating among servers. We propose a model for using virtual machines where storage processes are performed and migrate from host servers to guest servers.","Title: Object-Based Selective Delivery of Event Messages in Topic-Based Publish/Subscribe Systems\nYear: 2018\n\nAbstract: A peer-to-peer (P2P) model of a topic-based publish/subscribe system is composed of peer processes (peers) with no centralized coordinator. Each peer publishes a message with publication topics while receiving messages whose publications include subscription topics. Each peer has to causally deliver every pair of messages related in terms of topics. Based on objects carried by messages, we define on object-based-causally (OBC) and topic-based-causally (TBC) precedent relations among the messages. We newly propose a protocol to TBC-deliver messages to peers. If a message m(1) OBC-precedes a message m(2), m(1) TBC-precedes m(2). On the other hand, even if m(1) TBC-precedes m(2), m(1) may not OBC-precede m(2).","Title: Consideration of Implementation Method for the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\nYear: 2019\n\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, concept of implementation method applied for this scheme is described.","Title: Energy-Efficient Group Migration of Virtual Machines in a Cluster.\nYear: 2019\n\nAbstract: In order to realize green society, we take the process migration approach to reducing the total electric energy consumption of clusters by migrating virtual machines. In our previous studies, the DM (Dynamic Migration) algorithm is proposed where virtual machines are dynamically resumed and suspended and a group of virtual machines on a host server migrate to a guest server so that the total energy consumption of the host and guest servers can be reduced. In this paper, we newly propose a DGM (Dynamic Group Migration) algorithm. Here, there is a seed virtual machine on each server. A virtual machine is created as a clone of the seed virtual machine so that the number of processes on each virtual machine is kept fewer. In the evaluation, we show the total electric energy consumption of servers can be more reduced in the DGM algorithm compared with other algorithms.","Title: Selection of IoT Devices in Opportunistic Networks - A Fuzzy-Based Approach Considering IoT Device's Selfish Behaviour.\nYear: 2019\n\nAbstract: In opportunistic networks the communication opportunities (contacts) are intermittent and there is no need to establish an end-to-end link between the communication nodes. The enormous growth of devices having access to the Internet, along the vast evolution of the Internet and the connectivity of objects and devices, has evolved as Internet of Things (IoT). There are different issues for these networks. One of them is the selection of IoT devices in order to carry out a task in opportunistic networks. In this work, we implement a Fuzzy-Based System for IoT device selection in opportunistic networks. For our system, we use four input parameters: IoT Device’s Selfish Behaviour (IDSB), IoT Device Remaining Energy (IDRE), IoT Device Storage (IDST) and IoT Device Contact Duration (IDCD). The output parameter is IoT Device Selection Decision (IDSD). The simulation results show that the proposed system makes a proper selection decision of IoT devices in opportunistic networks. The IoT device selection is increased up to 14% and decreased 23% by increasing IDRE and IDSB, respectively.","Title: Performance Analysis of WMNs by WMN-PSODGA Simulation System Considering Weibull and Chi-square Client Distributions.\nYear: 2019\n\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. Then, we implemented a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. In this paper, we analyze the performance of WMNs using WMN-PSODGA simulation system considering Weibull and Chi-square client distributions. Simulation results show that a good performance is achieved for Chi-square distribution compared with the case of Weibull distribution.","Title: A Fuzzy-Based System for Actor Node Selection in WSANs Considering Level of Received Signal.\nYear: 2019\n\nAbstract: Wireless Sensor and Actor Network (WSAN) is formed by the collaboration of micro-sensor and actor nodes. The sensor nodes have responsibility to sense an event and send information towards an actor node. The actor node is responsible to take prompt decision and react accordingly. In order to provide effective sensing and acting, a distributed local coordination mechanism is necessary among sensors and actors. In this work, we consider the actor node selection problem and propose a fuzzy-based system (FBS) that based on data provided by sensors and actors selects an appropriate actor node. We use 4 input parameters: Distance to Event (DE), Number of Sensors per Actor (NSA), Remaining Energy (RE) and Level of Received Signal (LRS) as new parameter. The output parameter is Actor Selection Decision (ASD). Considering NSA parameter, the ASD has better values when NSA is medium. Thus, when the NSA value is 0.5 the load is distributed better and in this situation the possibility for the actor to be selected is high. Also, for higher values of LRS, the actor is selected with high possibility.","Title: The Improved Energy-Efficient Quorum Selection with Excluding Meaningless Methods.\nYear: 2019\n\nAbstract: In distributed object-based systems, applications manipulate objects distributed on multiple servers. In order to provide reliable and available application services, each object is replicated on multiple servers and replicas of each object have to be mutually consistent. On the other hand, since methods issued to each object are performed on multiple replicas, the total amount of electric energy consumed in a system increases. In our previous studies, the IEEQS (improved energy efficient quorum selection) algorithm is proposed to reduce the total electric energy of servers by omitting only meaningless write methods. In this paper, the IEEQS-EMM (IEEQS with excluding meaningless methods) algorithm is proposed to furthermore reduce the total electric energy of servers by omitting meaningless read and write methods. Evaluation results show the total electric energy of servers can be reduced in the IEEQS-EMM algorithm than the IEEQS algorithm.","Title: Efficient Information Flow Control by Reducing Meaningless Messages in P2PPSO Systems.\nYear: 2019\n\nAbstract: In topic-based publish/subscribe (PS) model, each peer process (peer) only receives an event message whose publication topics include some common topic with the subscription topics. In a P2PPSO (P2P (peer-to-peer) type of topic-based PS with Object concept) model, each peer exchanges objects by publishing and receiving event messages with no centralized coordinator. Here, objects are denoted by topics and event messages are characterized by topics of the objects carried by the event messages. Suppose an event message (e_j) published by a peer (p_j) carries objects on some topics into a target peer (p_i). Here, objects in the peer (p_j) illegally flow to the peer (p_i) if the peer (p_i) is not allowed to subscribe the topics. An object of a peer (p_i) is illegal, whose topics the peer (p_i) is not allowed to subscribe. In this paper, we newly propose an ETOBSCO (Efficient TOBSCO) protocol where meaningless event messages are not published to reduce the number of event messages exchanged among peers. In the evaluation, we show the fewer number of event messages are delivered but longer update delay time to update replicas is taken in the ETOBSCO protocol.","Title: Biometric-Based Linguistic Solutions for Data Encryption and Sharing.\nYear: 2019\n\nAbstract: This paper will describe new hybrid classes of secret sharing protocols joining features of linguistic secret division procedures with biometric threshold schemes. Such advanced protocols will be defined with application of different classes of formal grammars with standard or non-standard biometric patterns. Evaluation of such method will be done, as well as possible application for data and services management will be presented.","Title: Energy-Efficient Recovery Algorithm in the Fault-Tolerant Tree-Based Fog Computing (FTBFC) Model.\nYear: 2019\n\nAbstract: In order to reduce the traffic of networks and servers, the fog computing model is proposed to realize the IoT (Internet of Things). In our previous studies, the fault-tolerant tree-based fog computing (FTBFC) model is proposed to be tolerant of faults of fog nodes. If a fog node (f_{j}) is faulty, child fog nodes of (f_{j}) are disconnected. Another operational fog node (f_{i}) at the same level as (f_{j}) is a candidate parent node of disconnected nodes. One candidate node is selected to be a parent of every disconnected node. However, the new parent node (f_{i}) has to additionally process data from the disconnected nodes. In order to reduce the energy consumption of each new parent node, we propose a modified FTBFC (MFTBFC) model where disconnected nodes are partitioned into groups and fog nodes in each group are connected to a different candidate node. We also propose an SMPR (selecting multiple parents for recovery) algorithm to select a candidate parent node for each disconnected node so that the electric energy consumption of each new parent node can be reduced. In the evaluation, we show the energy consumption and execution time of each new parent fog node can be reduced in the SMPR algorithm.","Title: Centrality Based Geocasting for Opportunistic Networks.\nYear: 2019\n\nAbstract: Opportunistic networks (OppNets) are a subclass of delay tolerant networks characterized by unstable topology, intermittent connectivity, and no guarantee of the existence of an end-to-end path to carry the messages from source to destination because of node’s mobility. For these reasons, the routing of data in such networks occurs in a store-carry-and-forward approach. Following this approach combined with geocasting as message transmission strategy, this paper proposes a geo-casting protocol for OppNets named Centrality based Geocasting for OPPortunistic networks (CGOPP for short). The proposed scheme combines uni-casting and flooding by first transferring a message to an individual geographic location, then intelligently flood the message to all nodes inside the area by using a degree centrality function. Simulation results are provided, demonstrating the efficiency of the proposed protocol against traditional geo-casting protocols for OppNets, in terms of average latency, delivery ratio, and number of messages forwarded, under varying number of nodes, buffer sizes, and TTL.","Title: Linguistic and Biometric Approaches for Data and Services Management in Cloud Computing\nYear: 2018\n\nAbstract: This paper will describe new classes of secure secret sharing procedures applied for information and services management. In particular will be presented two classes of procedures which allow to share data and services, using personal biometric characteristics and mathematical linguistic approaches. Examples of application of such technologies will also be presented connected with distributed services in Cloud Computing infrastructures.","Title: Group Migration of Virtual Machines in a Server Cluster\nYear: 2018\n\nAbstract: In this paper, we propose an algorithm to migrate a group of virtual machines among servers in a cluster so that the total electric energy consumption of the host and guest servers can be reduced. We propose a pair of static SM(v) and dynamic DM(v) algorithms where at most v (>= 0) virtual machines migrate from a host server to a guest server. In the DM(v) algorithm, virtual machines are dynamically resumed and suspended as the number of application processes increases and decreases. In the evaluation, we show the total electric energy consumption of servers can be reduced in the DM(v) algorithm compared with other algorithms.","Title: Evaluation of Object-Based Information Flow Control in P2PPS Systems\nYear: 2018\n\nAbstract: In the P2PPSO (P2P (peer-to-peer) type of topic-based PS (publish/subscribe) with object concept) model, each peer process (peer) exchanges objects by publishing and subscribing event messages which are characterized by topics with no centralized coordinator. Information in a peer p(i) illegally flows to a peer p(j) if an event message e(i) published by the peer p(i) carries an object on some topics into the target peer p(j), which is not allowed to subscribe the topics. In our previous studies, a TOBS (topics of objects-based synchronization) protocol is proposed to prevent illegal information flow in the P2PPSO system. In the TOBS protocol, an illegal object whose topics a target peer is not allowed to subscribe is not delivered to the target peer. In this paper, we evaluate the TOBS protocol in terms of the number of event messages including at least one illegal object. In the evaluation, we show the number of event messages including illegal objects in the TOBS protocol.","Title: The Improved Transmission Energy Consumption Laxity-Based Algorithm with Parallel Data Transmission\nYear: 2018\n\nAbstract: Various kinds of approaches are proposed to reduce the total electric energy consumption of a server cluster system equipped with virtual machines. In order to design and implement energy-efficient server cluster systems, processing load of virtual machines to perform application processes has to be balanced with one another to not only reduce the total electric energy consumption of a server cluster but also satisfy application's performance requirements like turn-around time for each client. In this paper, the ITECLB-P (improved transmission energy consumption laxity based algorithm with parallel data transmission) algorithm is proposed to allocate communication processes to virtual machines in a server cluster so that the total electric energy consumption of a server cluster and the average turn-around time of each client can be reduced. In the evaluation, we show the total electric energy consumption of a server cluster and the average turn-around time of each client can be reduced in the ITECLB-P algorithm compared with the improved transmission energy consumption laxity based (ITECLB) algorithm.","Title: Performance Behavior of WMN-PSODGA Simulation System for WMNs Considering Uniform and Chi-Square Client Distributions\nYear: 2018\n\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We analyze the performance of WMNs using WMN-PSODGA simulation system considering Uniform and Chi-square client distributions. Simulation results show that the WMN-PSODGA has good performance for Chi-square distribution compared with the case of Uniform distribution.","Title: Information flow control in object-based peer-to-peer publish/subscribe systems: Information flow control in object-based peer-to-peer publish/subscribe systems\nYear: 2020\n\nAbstract: In this paper, we propose a P2PPSO (P2P [peer-to-peer] type of topic-based Publish/Subscribe with Object concept) model, where each peer process (peer) exchanges objects by publishing and receiving event messages with no centralized coordinator. In addition, objects are characterized by topics. Suppose an event message e(j) published by a peer p(j) carries an object on some topics into a target peer p(i). Here, information in the peer p(j) illegally flows to the peer p(i) if the target peer p(i) is not allowed to subscribe the topics. An illegal object is an object whose topics a target peer is not allowed to subscribe. Even if an event message is received by a target peer by checking topics, objects carried by the event message may be illegal at the target peer. In this paper, we propose a TOBS (topics-of-objects-based synchronization) protocol to prevent target peers from receiving illegal objects in the P2PPSO model. Here, even if an event message is received by a target peer, illegal objects in the event message are not delivered to the target peer. In the evaluation, we show how many event messages carry illegal objects in the TOBS protocol.","Title: Causally ordering delivery of event messages in P2PPSO systems\nYear: 2019\n\nAbstract: In topic-based PS (Publish/Subscribe) model, each peer process (peer) specifies subscription topics and publishes an event message with publication topics. A peer only receives an event message whose publication topics include some common topic with the subscription topics. In the P2PPSO (P2P (peer-to-peer) type of topic-based Publish/Subscribe with Object concept) model, each peer exchanges objects by publishing and receiving event messages with no centralized coordinator. Here, objects are denoted by topics and event messages are characterized by topics of the objects in the event messages. Suppose an event message ej published by a peer pj carries objects on some topics into a target peer pi. Information, i.e. objects in the peer pj illegally flows to the peer pi if the peer pi is not allowed to subscribe the topics. An illegal object of a peer pi is an object whose topics the peer pi is not allowed to subscribe. In the TOBS (Topics-of-Objects-Based Synchronization) protocol, illegal objects are not delivered to target peers, but every event message is assumed to be causally delivered in the underlying network. In this paper, we newly propose a TOBSCO (TOBS with Causally Ordering delivery) protocol where the function to causally deliver every pair of event messages is added to the TOBS protocol. In the evaluation, we show every pair of event messages are causally delivered and it takes longer to deliver event messages in the TOBSCO protocol.","Title: Evaluation of a Two-Way Tree-Based Fog Computing (TWTBFC) Model.\nYear: 2019\n\nAbstract: In our previous studies, the TBFC (Tree-Based Fog Computing) model is proposed to reduce the electric energy consumed by fog nodes and servers in the fog computing model. Here, fog nodes are hierarchically structured in a height-balanced tree. A root node shows a cloud of servers and leaf nodes are edge nodes which collect data from sensors and send actions to actuators. Each node receives data from child nodes and sends the processed data to a parent node. Finally, servers receive sensor data processed by fog nodes and send actions to actuators. Thus, sensor data is sent up to a root node from sensors and action are sent down to actuators from the root node. In order to more promptly deliver actions to actuators, the TWTBFC (Two-Way TBFC) model is proposed where nodes send processed data not only to a parent node but also to each child node. Thus, each node can get more global data obtained by processing data from every sibling node. The node can make a decision on actions to be done by descendant nodes. On the other hand, more amount of data is transmitted in networks and processed by a fog node. In this paper, we discuss how to reduce the processing load of each node in the TWTBFC model.","Title: The Improved Energy Consumption Laxity Based (IECLB) Algorithm to Perform Computation Processes.\nYear: 2019\n\nAbstract: The total electric energy consumption of a server cluster to perform application processes on multiple virtual machines has to be reduced to realize energy-efficient information systems. In our previous studies, the ECLB (energy consumption laxity based) algorithm to allocate computation type application processes (computation processes) to virtual machines in a server cluster is proposed so that the total electric energy consumption of the server cluster can be reduced. Here, each virtual machine is bounded to one thread on a CPU in a server and computation processes are performed by using only one thread bounded to the virtual machine even if some threads are not used in the server. In this paper, the improved ECLB (IECLB) algorithm is proposed to furthermore reduce the total electric energy consumption of a server cluster by allocating unused threads to each virtual machine to perform computation processes. We evaluate the IECLB algorithm in terms of the total electric energy consumption of a server cluster compared with the ECLB algorithm.","Title: Capability-Based Information Flow Control Model in the IoT.\nYear: 2019\n\nAbstract: Various types and huge number of nodes including not only computers like servers but also devices like sensors and actuators are interconnected in the IoT (Internet of Things). Here, the CapBAC (Capability-Based Access Control) model is proposed in the IoT system. In the CapBAC model, an owner of a device issues a capability token, i.e. a set of access rights to a subject. Here, the subject is allowed to manipulate the device according to the access rights in the capability token. In the IoT, a subject sb(i) can get the data of the device d(1) from another device d(2) to which the data of the device d(1) is brought although the subject sb(i) is not allowed to get the data from the device d(1). Here, the data in the device d(1) illegal flows to the subject sb(i). In this paper, first, we newly define information flow relations among devices based on the CapBAC model. Next, we newly propose an OI (Operation Interruption) protocol to prevent illegal information flow in the IoT based on the information flow relations among devices. In the OI protocol, an operation to imply illegal information flow is interrupted.","Title: A Synchronization Protocol to Prevent Illegal Information Flow Based on Maximal Roles in the Role-Based Access Control Model.\nYear: 2018\n\nAbstract: In access control models, a transaction is allowed to read and write an object only if access rights to read and write the object are granted, respectively. Suppose a transaction T-1 reads data d from a file object f(1) and then writes the data d to another file object f(2). Here, another transaction T-2 can get the data d by reading the file object f(2) even if T-2 is not granted a read right on the file object f(1). Here, information in the file object f(1) flows to the transaction T-2 via the file object f(2). We have to prevent illegal information flow to occur by transactions manipulating objects. The role-based access control (RBAC) model is widely used in various applications like database systems. In our previous studies, the legally precedent relation from a role to a role is defined. However, even if the legal condition is satisfied, there is case illegal information flow occurs. In this paper, we redefine legal and illegal precedent relations among roles. In order to check if a collection A of roles illegally precedes a collection B of roles, we introduce a new condition which uses maximal roles of A and B.","Title: A Fuzzy-Based System for Safe Driving Information in VANETs.\nYear: 2018\n\nAbstract: Ambient intelligence (AmI) deals with a new world of ubiquitous computing devices, where physical environments interact intelligently and unobtrusively with people. AmI environments can be diverse, such as homes, offices, meeting rooms, schools, hospitals, control centers, vehicles, tourist attractions, stores, sports facilities, and music devices. In this paper, we propose a Fuzzy-based system for safe driving information in VANETs. The proposed system considers in-car environment data and driver's vital signs data to make the decision. Then uses the smart-box to inform the driver and change his mood. We want to realize a new system to support the driver for save driving. We evaluated the performance of proposed system by computer simulations. From the simulations results, we conclude that the driver vital information, vehicle mobility information and car environment information have different effects to the driver.","Title: Performance Comparison Of Cm And Ldvm Router Replacement Methods For Wmns By Wmn-Psosa-Dga Hybrid Simulation System Considering Stadium Distribution Of Mesh Clients\nYear: 2021\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as: easy maintenance, low upfront cost and high robustness. The connectivity and stability affect directly the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we compare the performance of Constriction Method (CM) and Linearly Decreasing Vmax Method (LDVM) for WMNs by using the WMN-PSOSA-DGA hybrid simulation system considering the Stadium distribution of mesh clients. Simulation results show that LDVM has better performance than CM.","Title: Transformative Computing Based On Advanced Human Cognitive Processes\nYear: 2021\n\nAbstract: Currently, data analysis processes based on individual, personalized recording techniques are used more and more. Such processes allow for intelligent data analysis considering only those elements that are of significant importance to a specific recipient. In addition, they provide the possibility of applying individual analysis results to deep data analysis processes. In this paper, such possibilities of data analysis will be described, with particular emphasis on the use of transformational computing technology taking into account advanced human cognitive processes.","Title: Performance Evaluation of WMNs by WMN-PSOSA-DGA Hybrid Simulation System Considering Stadium Distribution of Mesh Clients and Different Number of Mesh Routers\nYear: 2021\n\nAbstract: Wireless Mesh Networks (WMNs) are gaining a lot of attention from researchers due to their advantages such as easy maintenance, low upfront cost, and high robustness. Connectivity and stability directly affect the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we evaluate the performance of WMNs by using the WMN-PSOSA-DGA hybrid simulation system considering the Stadium distribution of mesh clients. Simulation results show that 32 mesh routers are enough for maximizing the network connectivity and user coverage.","Title: The Redundant Active Time-Based Algorithm with Forcing Meaningless Replica to Terminate\nYear: 2021\n\nAbstract: Reliable and available distributed application services can be provided by redundantly performing each application process. However, multiple replicas of each application process are performed on multiple virtual machines in a server cluster system. As a result, a server cluster consumes a large amount of electric energy to provide application services. In this paper, the RATB-FMRT (redundant active time-based with forcing meaningless replicas to terminate) algorithm is proposed to reduce the total electric energy consumption of a server cluster by forcing meaningless replica to terminate. In the evaluation, we show the total electric energy consumption of a server cluster and the average response time of each process can be reduced in the RATB-FMRT algorithm.","Title: Information Flow Control Based on Capability Token Validity for Secure IoT: Implementation and Evaluation\nYear: 2021\n\nAbstract: In the CBAC (Capability-Based Access Control) model proposed for realizing the secure IoT (Internet of Things), authorizers issue subjects capability tokens, i.e. sets of access rights on objects in devices. Objects are data resources which are used to store sensor data and action data. Data of an object may be stored in another object through communication among subjects and devices. A subject can get data of an object from another object even if the subject is not allowed to get the data, i.e. information illegally flows from the object to the subject. In addition, a subject can get data generated at time before which the capability token to get the data starts to be valid. Here, information flows from the object to the subject later than expected by the subject to get the data. In our previous studies, the OI (Operation Interruption) and the TBOI (Time-Based OI) protocols are proposed to interrupt operations implying illegal type of information flow and not only illegal but also late types of information flows, respectively. In this paper, the TBOI protocol is designed and implemented. In the evaluation, it is shown the late information flow is prevented in addition to the illegal one in the TBOI protocol although the request processing time is almost the same as the OI protocol.","Title: Probability And Topic-Based Data Transmission Protocol\nYear: 2021\n\nAbstract: In the fog computing (FC) models, a fog node supports not only routing functions but also application processes. By the application processes, output data are calculated on input data from sensors and other nodes and sent to target fog nodes which can calculate on the output data. In this article, we consider the mobile topic-based publish/subscribe fog computing (MPSFC) model where mobile fog nodes communicate with one another by publishing and subscribing messages in wireless networks. Subscription topics of a fog node denote input data on which the node can calculate output data. Publication topics of a message show data carried by the message. In the topic-based data transmission (TBDT) protocol proposed in our previous studies, while a fewer number of messages are transmitted, the delivery ratio of messages is smaller than the epidemic routing protocol. In this article, we newly propose a pair of time-to-live-based data transmission (TTLBDT) and probability and topic-based data transmission (PTBDT) protocols in order to increase the delivery ratio. If another node is found in the communication range, a fog node forwards messages to the node. Even if the node is not a target node, the node receives the message with some probability in the PTBDT protocol. In the evaluation, we show the delivery ratios in the TTLBDT and PTBDT protocols are larger than the TBDT protocol. In addition, we show the number of messages exchanged in the PTBDT protocol is smaller than the epidemic routing protocol.","Title: Performance Analysis of RIWM and RDVM Router Replacement Methods for WMNs by WMN-PSOSA-DGA Hybrid Simulation System Considering Stadium Distribution of Mesh Clients\nYear: 2021\n\nAbstract: Wireless Mesh Networks (WMNs) have many advantages, for example easy maintenance, low upfront cost and high robustness. However, WMNs have some problems to be solved such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we compare the performance of Random Inertia Weight Method (RIWM) and Rational Decrement of Vmax Method (RDVM) for WMNs by using WMN-PSOSA-DGA hybrid simulation system considering Stadium distribution of mesh clients. Simulation results show that RDVM has better performance than RIWM.","Title: Modern Cognitive Solutions for Advanced Information Processing\nYear: 2021\n\nAbstract: This paper will discuss modern cognitive solutions dedicated to information processing. Cognitive processes, as the most individual methods of information processing, are characteristic of every human being, and thus transferred to the ground of machine solutions, they offer the possibility of deep, meaningful data analysis. Their distinguishing feature is that they are based on a semantic interpretation based on a linguistic description. The possibility of using such solutions in information processing will allow to show their universality and usefulness.","Title: An Energy-Efficient Algorithm to Make Virtual Machines Migrate in a Server Cluster\nYear: 2021\n\nAbstract: Applications can take advantage of virtual computation services independently of heterogeneity and locations of servers by using virtual machines in clusters. Here, a virtual machine on an energy-efficient host server has to be selected to perform an application process. In this paper, we propose an SMI (Simple MI) algorithm to estimate the energy consumption of a server to perform application processes. Then, we propose an SMIM (SMI Migration) algorithm to make a virtual machine migrate from a host server to a guest server to reduce the total energy consumption of the servers by using the SMI algorithm. In the evaluation, we show the energy consumption of servers in a cluster can be reduced in the SMIM algorithm compared with other algorithms.","Title: Time-based legality of information flow in the capability-based access control model for the Internet of Things\nYear: 2021\n\nAbstract: The Internet of Things is composed of sensor and actuator devices. Devices have to be securely accessed by subjects. In this article, we take the capability-based access control (CBAC) model where a subject is issued a capability token to manipulate a device by a device owner. In the CBAC model, information which a subject is not allowed to get may illegally flow to the subject. Hence, the operation interruption (OI) protocol to prevent illegal information flow is proposed in our previous studies. However, although a subject is not allowed to get data at time tau, the subject can get the data later than the time tau. Here, the data come to the subject later than expected by the subject to get the data, that is, the information flows late to the subject. In this article, we newly propose a time-based OI (TBOI) protocol to prevent not only illegal information flow but also late information flow. Here, operations implying illegal or late information flow are interrupted, that is, not performed at devices. In the evaluation, we show not only illegal information flow but also late information flow are prevented in the TBOI protocol differently from the OI protocol.","Title: A comparison study of chi-square and uniform distributions of mesh clients for different router replacement methods using WMN-PSODGA hybrid intelligent simulation system\nYear: 2021\n\nAbstract: Wireless Mesh Networks (WMNs) are gaining a lot of attention from researchers due to their advantages such as easy maintenance, low upfront cost and high robustness. Connectivity and stability directly affect the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO) and Distributed Genetic Algorithm (DGA), called WMN-PSODGA. In this paper, we compare chi-square and uniform distributions of mesh clients for different router replacement methods. The router replacement methods considered are Constriction Method (CM), Random Inertia Weight Method (RIWM), Linearly Decreasing Inertia Weight Method (LDIWM), Linearly Decreasing Vmax Method (LDVM) and Rational Decrement of Vmax Method (RDVM). The simulation results show that for chi-square distribution the mesh routers cover all mesh clients for all router replacement methods. In terms of load balancing, the method that achieves the best performance is RDVM. When using the uniform distribution, the mesh routers do not cover all mesh clients, but this distribution shows good load balancing for four router replacement methods, with RIWM showing the best performance. The only method that shows poor performance for this distribution is LDIWM. However, since not all mesh clients are covered when using uniform distribution, the best scenario is chi-square distribution of mesh clients with RDVM as a router replacement method.","Title: Capability token selection algorithms to implement lightweight protocols\nYear: 2022\n\nAbstract: The IoT (Internet of Things) is now one of the most significant infrastructure and has to be secure against malicious accesses. Especially, it is critical to make devices secure in the IoT. In the CBAC (Capability-Based Access Control) model adopted to the IoT, device owners issue subjects capability tokens, i.e. a set of access rights on objects in devices. Objects in devices are data resource manipulated by subjects. Data are exchanged among subjects and objects through manipulating objects. Here, if subjects attempt to manipulate objects in accordance with the capability tokens issued, the subjects can get data which the subjects are not authorized to get, i.e. illegal information flow and late information flow occur. In our previous studies, protocols are implemented to prevent both illegal and late types of information flows from occurring. Here, operations implying such information flows are interrupted. However, the request processing time gets longer as the number of capability tokens used increases. In this paper, an MRCTSD (Minimum Required Capability Token Selection for Devices) algorithm is newly proposed to reduce the number of capability tokens used. In the evaluation, it is shown that the request processing times and the numbers of capability tokens used in the lightweight protocols realized with the MRCTSD algorithm are shorter and smaller than the conventional protocols, respectively.","Title: An energy-efficient quorum-based locking protocol by omitting meaningless methods on object replicas\nYear: 2022\n\nAbstract: In current information systems, a huge number of IoT (Internet of Things) devices are interconnected with various kinds of networks like WiFi and 5G networks. A large volume of data is gathered into servers from a huge number of IoT devices and is manipulated to provide application services. Gathered data is encapsulated along with methods to manipulate the data as an object like a database system. In objectbased systems, each application is composed of multiple objects. In addition, each object is replicated on multiple physical servers in order to increase availability, reliability, and performance of an application service. On the other hand, replicas of each object is required to be mutually consistent in presence of multiple transactions. Here, a larger amount of electric energy and computation resources are consumed in physical servers than non-replication approaches to serialize conflicting transactions on multiple replicas. Many algorithms to synchronize conflicting transactions are so far proposed like 2PL (Two-Phase Locking) and TO (Timestamp Ordering). However, the electric energy consumption is not considered. In this paper, an EEQBL-OMM (Energy-Efficient Quorum-Based Locking with Omitting Meaningless Method) protocol is newly proposed to reduce not only the average execution time of each transaction but also the total electric energy consumption of servers by omitting the execution of meaningless methods on replicas of each object. Evaluation results show the total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted instances of transactions in the EEQBL-OMM protocol can be on average reduced to 79%, 62%, and 80% of the ECLBQS (Energy Consumption Laxity-Based Quorum Selection) protocol which is proposed in our previous studies in a homogeneous set of servers, respectively. In addition, the evaluation results show the total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted instances of transactions in the EEQBL-OMM protocol can be on average reduced to 73%, 50%, and 67% of the ECLBQS protocol in a heterogeneous set of servers, respectively. The evaluation results also show at most 48% and 51% of the total number of methods can be omitted as meaningless methods in a homogeneous set and heterogeneous set of servers, respectively, in the EEQBL-OMM protocol."],"string":"[\n \"Title: Experimental Results of a Raspberry Pi Based WMN Testbed for Different OSs in Indoor Environment Considering LoS Scenario.\\nYear: 2015\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using Raspbian and OpenWRT OSs. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario. For evaluation we considered throughput, Packet Delivery Ratio (PDR), delay, jitter and hop count metrics. The experimental results show that the testbed mounted in OpenWRT has better results than Raspbian.\",\n \"Title: Energy-Aware Migration and Replication of Processes in a Cluster\\nYear: 2015\\n\\nAbstract: Application processes have to be efficiently performed in presence of server faults in a cluster. Replicas of a process are performed on multiple servers to be tolerant of server faults. However, the more number of replicas of a process are performed, the more reliably and available the process can be performed but the more amount of electric energy is consumed by servers. In this paper, we take a process migration approach to reliably and energy-efficiently performing process replicas. A process is replicated to multiple replicas. Each replica is performed on a server different from the other replicas to realize fault-tolerant computation. In addition, each replica of process migrates from a current server to another server if the current server is expected to consume the more electric energy. Thus, replicas migrate to servers to reduce the total electric energy consumption of the cluster.\",\n \"Title: Power Consumption and Computation Models of a Storage Server.\\nYear: 2015\\n\\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems including a huge number of servers like cluster computing systems. Types of application processes like computation, storage, and communication processes are performed on servers in clusters. In clusters, most applications use not only CPU resources but also storage drives like database and web applications. In this paper, we consider storage processes which read and write files in storage devices. The SPCS model (simple power consumption model for a storage server) shows how much electric power a server consumes to perform storage and computation processes. In our macro-level approach, we first measure the electric power consumed by a whole server to perform storage and computation processes and the computation time of each process. Then, we define the SPCS model of a server to perform storage and computation processes by abstracting parameters like number of processes which dominate the electric power consumption. We also define a simple computation model for a storage server (SPCS model) to perform storage and computation processes.\",\n \"Title: Role Safety in a Flexible Read-Write Abortion Protocol.\\nYear: 2015\\n\\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally reads an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the flexible read-write-abortion with role sensitivity (FRWA-R) and object sensitivity (FRWA-O) protocols are discussed to prevent illegal information flow. Here, a transaction is aborted with some probability once illegally reading an object. The abortion probability depends on the sensitivity of roles which the transaction holds and objects which the transaction illegally reads. The role sensitivity and object sensitivity show how many transactions which hold the role and illegally read the object are aborted after illegally reading the object, respectively. Here, the sensitivity just monotonically increases each time a transaction is aborted. In this paper, we newly propose a safety concept of a role and an FRWA with role safety (FRWA-RS) protocol where the safety of a role increases and decreases if a transaction holding the role and illegally reading objects commits and aborts, respectively. A transaction with safer roles is aborted with smaller probability. In the evaluation, we show a fewer number of transactions are aborted in the FRWA-RS protocol than the RWA protocol while more than the WA protocol and transactions are more efficiently performed than the WA protocol.\",\n \"Title: Reliable and Efficient Parallel Transmission Protocols in P2P Networks.\\nYear: 2015\\n\\nAbstract: In infrastructureless networks like P2P networks and mobile ad hoc networks, a pair of nodes are not always supported with reliable and efficient communication. For example, some relay nodes may be faulty and a communication link between some pair of neighboring nodes may be degraded in QoS due to noise. In this paper, we propose a parallel transmission protocol for reliably and efficiently transmitting data in P2P overlay networks. Packets of data are transmitted in multiple communication paths to support enough QoS. Even if each communication path does not support applications wit enough QoS, amount of QoS supported by multiple communication paths can support enough QoS. A subsequence of packets are in addition replicated with a parity packet in order to be tolerant of packet loss. Even if a packet is lost, the lost packet can be recovered by the parity packet and the other packets in the subsequence. Packets are lost in a burst manner. In order to be tolerant of burst loss of packets in a communication path, we discuss vertical and horizontal parity packets. We discuss how packets of data are allocated to multiple communication paths in order to increase the throughput and are replicated to be tolerant of burst packet loss.\",\n \"Title: Energy-Efficient Virtualisation of Threads in a Server Cluster.\\nYear: 2015\\n\\nAbstract: It is critical to reduce the electric power consumed by servers in a cluster in order to realize eco society. In our previous studies, the multi-level power consumption (MLPC) model of a server with a multi-thread CPU, the power consumption of the server is proposed and the globally energy-aware (GEA) algorithm is discussed to select a server for each process in a cluster. Here, not only the total electric energy consumption of all the servers but also the ratio of the basic electric energy consumed by the servers to the total electric energy consumption can be reduced in a cluster. However, the GEA algorithm is not scalable since every server is checked to find a server for each process in a cluster. In this paper, we newly propose a scalable energy-aware (SEA) algorithm to select a server for a process. Here, some number of servers are first randomly selected in a cluster and one server is then selected in the selected servers by the GEA algorithm. We evaluate the SEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the SEA algorithm compared with other algorithms.\",\n \"Title: Evaluation of Energy-Aware Server Selection Algorithms\\nYear: 2015\\n\\nAbstract: The electric power consumed by servers has to be reduced in a cluster in order to realize eco society. We take a macro level approach to reducing the total electric energy consumption of servers to perform application processes in a server cluster. Servers are now equipped with multi-core CPUs. In this paper, we discuss a multi-level power consumption (MLPC) model of a server with a multi-core CPU. Here, the power consumption of a server depends on the number of active cores and active threads where at least one application process is performed. We also discuss a multi-level computation (MLC) model which gives the expected execution time of a process which is concurrently performed with other processes on a server with a multi-core CPU. Based on the MLPC model and the MLC model, we discuss an energy-aware (EA) algorithm to select a server for each process requested by a client in a cluster so as to reduce the total electric energy consumption while satisfying deadline requirements of the processes. We evaluate the EA algorithm and show not only the total energy consumption but also the average execution time of each process is reduced in the EA algorithm compared with the round-robin (RR) and random (RD) algorithms.\",\n \"Title: Energy-Efficient Replication and Migration of Processes in a Cluster\\nYear: 2015\\n\\nAbstract: Application processes have to be efficiently performed in presence of server faults in a cluster. Multiple replicas of a process are performed on multiple servers. However, the more number of replicas of a process are performed, the more reliable and available the process can be performed but the more amount of electric energy is consumed. In this paper, we take a process migration (MG) approach to energy efficiently and reliably performing multiple replicas of an application process on servers. A replica of a process performed on a current server st migrates to another server su if the server su is expected to consume a smaller amount of electric energy to perform the replica than the current server st while the deadline constraint of the process is satisfied. We consider synchronous and asynchronous ways for process replicas to migrate to servers. In the synchronous migration, every replica migrates to another server on a same computation state. In the asynchronous migration, each replica makes a decision on when the replica migrates to which server.\",\n \"Title: Power Consumption and Computation Models of Virtual Machines to Perform Computation Type Application Processes\\nYear: 2015\\n\\nAbstract: Scalable and fault-tolerant information systems like cloud systems are realized in server cluster systems. Server cluster systems are equipped with virtual machines to provide applications with scalable and fault-tolerant services. Scalable and fault-tolerant application services can be provided by balancing processing load among virtual machines to perform application processes. On the other hand, a large amount of electric energy is consumed in a server cluster system since multiple virtual machines are performed on multiple servers which consume electric energy to perform application processes. In order to design and implement an energy-aware server cluster system, the computation model and power consumption model of a server to perform application processes on multiple virtual machines have to be defined. In this paper, we first define the computation model of a virtual machine to perform application processes. We also define the power consumption model of a server to perform application processes on virtual machines.\",\n \"Title: A Flexible Read-Write Abortion Protocol with Sensitivity of Objects to Prevent Illegal Information Flow\\nYear: 2015\\n\\nAbstract: In information systems, objects have to be not only legally accessed in presence of illegal accesses but also data in a suspicious object is not allowed to flow to another object. A transaction illegally and suspiciously reads an object if the transaction reads the object which includes data in other objects which are not allowed to be read and the object which is suspicious, respectively. A transaction illegally and impossibly writes an object after illegally and suspiciously reading an object, respectively. The write-abortion (WA), read-write-abortion (RWA), and flexible RWA (FRWA) protocols to prevent illegal information flow are proposed in our previous papers. In the WA and RWA protocols, a transaction is aborted once issuing an illegal or impossible write and issuing an illegal read or impossible write, respectively. Reads are meaninglessly performed since the reads are later undone due to the abortion of the transaction in the WA protocol. Reads which can be performed after an illegal read are not performed, i.e. Lost since a transaction is aborted just once issuing an illegal read in the RWA protocol. In the FRWA protocol, a transaction is aborted with some probability once illegally reading an object in order to reduce the number of meaningless and lost reads. We newly introduce the sensitivity concept of an object in order to decide on the abortion probability. The more number of transactions are aborted after illegally reading an object, the more highly sensitive the object is. A transaction which illegally reads a more sensitive object is aborted with higher probability. In the evaluation, we show the execution time of each transaction in the FRWA protocol is shorter than WA and more number of reads can be performed than RWA.\",\n \"Title: Concurrency Control Based on Subject and Purpose Concepts\\nYear: 2007\\n\\nAbstract: A subject doing a job function plays a role in an enterprise. In the role-based access control model, a role is a set of access rights. A subject granted a role can issue an access request in the role. In addition, objects are required to be consistent even if multiple transactions concurrently manipulate an object in a conflicting way. Here, a subject playing more significant roles should take the object prior to another subject. First, we discuss which roles are more significant than other roles in terms of types of methods. Next, we define which subject is moresignificant in terms of significancy of roles and authorization relations. A method issued by a more significant subject should be performed before another conflicting method issued by a less significant subject in the subject-oriented (SO) view. A transaction issued by a subject is associated with a subset of roles granted to the subject, which is named purpose. A method with a more significant purpose should be performed before another method with a less significant purpose in the purpose-oriented (PO) view. In this paper, we discuss how conflicting methods are ordered in a unique SO and PO (SPO) view. We discuss an SPO scheduler where multiple conflicting transactions are serializable in the SPO view. We evaluate the SPO scheduler compared with the traditional two-phase locking protocol in terms of throughput.\",\n \"Title: A GA-Based Simulation System for WMNs: Performance Analysis of WMN-GA System for Different WMN Architectures Considering DCF and EDCA\\nYear: 2015\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In our previous work, we evaluated WMN-GA system which is based on Genetic Algorithms (GAs) to find an optimal location assignment for mesh routers. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance for Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for normal distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the throughput of I/B WMN is higher than Hybrid WMN architecture. The delay and jitter of Hybrid WMN is a lower compared with I/B WMN. The fairness index of 10 and 20 flows is higher than 30 flows for both architectures. In I/B architecture the fairness index of DCF is higher than EDCA. However, for Hybrid WMN, the fairness index of EDCA is higher than DCF.\",\n \"Title: An Energy-Efficient Load Balancing Algorithm to Perform Computation Type Application Processes for Virtual Machine Environments.\\nYear: 2015\\n\\nAbstract: There are various types of high performance, scalable, and fault-tolerant information systems like cloud systems to realize applications on distributed systems. Virtual machines are used to realize these distributed applications in server cluster systems. In order to satisfy application requirements like deadline constraint for each application process, processing load of virtual machines has to balance with one another in a server cluster system. Here, in addition to achieving the performance objectives, the total electric energy consumption of a server cluster system to perform application processes has to be reduced as discussed in Green computing since a server cluster system is composed of large number of servers and consumes a large amount of electric energy to perform application processes. In our previous studies, the power consumption model of a server to perform application processes on virtual machines which migrate on servers is proposed. In addition, the computation model of a virtual machine to perform computation type application processes is proposed. In this paper, we propose the energy consumption laxity based (ECLB) algorithm to allocate computation type application processes to virtual machines in a server cluster based on the proposed computation model and power consumption model so that the total energy consumption of a server cluster and computation time of each process can be reduced. We evaluate the ECLB algorithm in terms of the total energy consumption of a server cluster and computation time of each process compared with basic round-robin (RR) algorithm. Evaluation results show the average total energy consumption of a server cluster and average computation time of each process in the ECLB algorithm can be maximumly reduced to 1.9% and 12.6% of the RR algorithm, respectively.\",\n \"Title: Reduction of Unnecessarily Ordered Messages in Scalable Group Communication.\\nYear: 2015\\n\\nAbstract: In distributed applications, multiple processes are cooperating with one another by exchanging messages in networks. Information systems like cloud computing systems are getting scalable, which are composed of a huge number of processes. In group communications, messages sent by processes have to be causally delivered to every process in a group. The vector clock is widely used in group communication protocols but cannot be adopted to scalable groups due to communication and computation overheads. In the linear clock, the message length is O(1) but some pairs of messages are unnecessarily ordered even if the messages are not required to be causally delivered. In this paper, we discuss a communication protocol for a scalable group where linear clock and physical clock are used to reduce the number of pairs of messages unnecessarily ordered. We consider a group of multiple processes where the maximum offset of every physical clock is the same, i.e. homogeneous clock but maximum delay time between every pair of processes is not the same, i.e. heterogeneous network. We evaluate the protocol and show the number of pairs of unnecessarily ordered messages can be reduced compared with the linear clock protocol.\",\n \"Title: Eco Models of Storage-Based Severs.\\nYear: 2015\\n\\nAbstract: Information systems are getting scalable like cloud computing systems and Internet of Things (IoT). It is critical to reduce electric energy consumed in our society. In information systems, we have to reduce the electric energy consumed by computers, especially servers in clusters to perform application processes. Types of application processes like computation, storage, and communication processes are performed on servers in clusters. Computation processes consume CPU resource to do the computation like scientific computation. The power consumption models like simple power consumption (SPC) and multi-level power consumption (MLPC) models are already proposed for computation processes in our previous studies. In this paper, we consider storage processes which read and write files in storage devices. We newly propose a simple power consumption model for a storage of a server (SPCS model), which shows how much electric power the server consumes to perform storage and computation processes. In our macro-level approach, we first measure the electric power consumed by a whole server to perform storage and computation processes. Then, we define the SPCS model of a server to perform storage and computation processes by abstracting parameters like number of processes which dominate the electric power consumption.\",\n \"Title: On Streaming Consistency of Big Data Stream Processing in Heterogenous Clutsers.\\nYear: 2015\\n\\nAbstract: There is currently a growing interest on Big Data Stream processing. With the increasing capabilities of Internet-based computing systems to generate, store and process Big Data Streams, various applications are benefiting from the information extracted in real time from data streams. Such families of applications comprise IoT-based monitoring systems, decision making systems, recommendation systems, security, etc. In all of them, the common ingredient is that of using real time data analytics for the purpose at hand. The foremost challenge of processing Big Data Streams is that of throughput performance, i.e., the computing system should be able to compute at high throughput to accommodate the high data stream rate generation in input. Additionally to this challenge, the processing should be such that the consistency of streaming is achieved. The consistency of streaming requires that the order of events in the original stream (in input) is preserved also in the output. In this paper we show that using a heterogeneous cluster for Big Data Stream processing could indeed incur into streaming inconsistency and one would indeed have to carefully tune the system so that streaming consistency is achieved. We exemplify the approach using the Yahoo!S4 for processing the Big Data Stream from FlightRadar24 global flight monitoring system.\",\n \"Title: Trustworthiness in Peer-to-Peer Systems.\\nYear: 2015\\n\\nAbstract: A peer-to-peer (P2P) system is composed of peer processes (peers) interconnected in overlay networks. A peer has to communicate only with acquaintance peers due to the scalability and autonomy of the P2P system. A peer can collect information on objects distributed in P2P systems through communicating with the acquaintance peers. Peers may hold obsolete information and be faulty. Hence, a peer has to collect information from trustworthy acquaintance peers. The trustworthiness of an acquaintance peer is defined in terms of multiple parameters like response time and number of correct replies. It is difficult to obtain the trustworthiness due to the complex calculation of multiple parameter. In this paper, we discuss trustworthiness of an acquaintance peer in Fuzzy logics.\",\n \"Title: Performance Evaluation of a WMN Testbed in Indoor Environment Considering Mobile Mesh Node Scenario.\\nYear: 2015\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. Considering mobility of the terminals, routing is a key process for operation of WMNs. In this paper, we present the implementation of a testbed for WMNs. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario considering mobile mesh node. For evaluation we considered throughput, Packet Delivery Ratio (PDR), hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly and we got good values for five parameters.\",\n \"Title: A Flexible Read-Write Abortion Protocol with Sensitivity of Roles.\\nYear: 2015\\n\\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally and suspiciously reads an object if the object includes data in other objects which are not allowed to be read and the object is suspicious, respectively. A transaction illegally and impossibly writes an object after illegally and suspiciously reading an object, respectively. In this paper, we discuss the flexible read-write-abortion with role sensitivity (FRWA-R) protocol where a transaction is aborted with some probability once illegally reading an object. The abortion ratio depends on the sensitivity of roles which the transaction holds. The sensitivity of a role shows how many transactions which holds the role are aborted after illegally reading an object. The more number of roles to which illegal information flow for a role occur, the lower sensitive the role is. A transaction with lower sensitive roles which illegally reads an object is aborted with higher probability. In the evaluation, we show the execution time of each transaction in the FRWA-R protocol is shorter than the WA protocol and more number of reads can be performed than the RWA protocol.\",\n \"Title: Performance Evaluation of a Neural Network Based Intrusion Detection System for Tor Networks Considering different Hidden Units.\\nYear: 2015\\n\\nAbstract: Due to the amount of anonymity afforded to users of the Tor infrastructure, Tor has become a useful tool for malicious users. With Tor, the users are able to compromise the non-repudiation principle of computer security. Also, the potentially hackers may launch attacks such as DDoS or identity theft behind Tor. For this reason, there are needed new systems and models to detect the intrusion in Tor networks. In this paper, we present the application of Neural Networks (NNs) for intrusion detection in Tor networks. We used the Back-propagation NN and constructed a Tor server and a Deep Web browser (client). Then, the client sends the data browsing to the Tor server using the Tor network. We used Wireshark Network Analyzer to get the data and then used the Backpropagation NN to make the approximation. We present many simulation results for different number of hidden units. The simulation results show that our simulation system has a good approximation and can be used for intrusion detection in Tor networks.\",\n \"Title: Suggestion of the Cloud Type Virtual Policy Based Network Management Scheme for the Common Use between Plural Organizations.\\nYear: 2015\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leak and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the course between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have been studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. As the second step for the last goal, we show the concept of the cloud type virtual PBNM which can be used by plural organizations in this paper.\",\n \"Title: Energy-Efficient Broadcast Protocols in Wireless Network\\nYear: 2015\\n\\nAbstract: It is significant to deliver messages to every node in a group to realize the cooperation of the nodes in wireless networks. In order to reduce the number of messages in the flooding protocols, the multi-point relay (MPR) protocols are discussed where only relay nodes forward messages and the other leaf nodes do not forward messages. In this paper, we discuss broadcast protocols where the total electric energy consumed by nodes to deliver messages to every node can be reduced. We newly propose energy-efficient broadcast (EEB) protocol, modified EEB (EEB2) protocol, and augmented EEB (AEEB) protocol. In the EEB protocol, a first-neighbour node to which another first-neighbour node cannot more energy-efficiently deliver messages is selected as a child node of a relay node. In the EEB2 protocol, child nodes are first selected for a relay node in the same way as the EEB protocol. In addition, a farthest child node steps down to a lower level to reduce the electric energy of the relay nodes. In the AEEB protocol, for each uncovered node pi which is a first-neighbour node of the nodes of level l, a node pj of the level l is selected as a parent node of the node pi if the electric energy consumed by the node pj to deliver a message to the node pi is the smallest. We evaluate the EEB and EEB2 protocols and show the total electric energy consumed by nodes can be reduced.\",\n \"Title: A New FACS for Cellular Wireless Networks Considering QoS: A Comparison Study of FuzzyC with MATLAB.\\nYear: 2015\\n\\nAbstract: Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In this paper, we evaluate the accuracy of implemented Fuzzy-based system written in C-language (FuzzyC) for CAC. For evaluation, we propose a new CAC scheme which considers for acceptance decision except other parameters also the QoS. We compared the performance of FuzzyC with MATLAB. The evaluation results show the FuzzyC has a good accuracy.\",\n \"Title: Selective Delivery of Event Messages in Peer-to-Peer Topic-Based Publish/Subscribe Systems.\\nYear: 2015\\n\\nAbstract: A distributed system is considered in an eventdriven model where states of processes transit on occurrence of events. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe (P2PPS) system where each peer process (peer) pi can both subscribe a subscription pi:S and publish an event message e with a publication e:P. The subscriptions and publications are specified in terms of topics, i.e. keywords. An event message e is notified to a target peer pi whose subscription pi:S includes a common keyword with the publication e:P. Each event message e carries a vector e:KV = (kv1,
, kvm) of keywords k1,
, km. An event message e1 causally precedes an event message e2 with respect to a subscription Si iff not only e1 causally precedes e2 but also e1:kvh\",\n \"Title: Multi-level Computation and Power Consumption Models.\\nYear: 2015\\n\\nAbstract: It is critical to reduce the electric power consumed by servers in a cluster in order to realize eco society. In the multi-level power consumption (MLPC) model of a server with a multi-core CPU, the power consumption of the server depends on the number of active cores and active threads where at least one application process is performed. In our previous studies, we discuss the energy-aware (EA) selection algorithm to select a server for each request process. Here, a server which is expected to consume the minimum electric energy is selected in a cluster. A server consumes the basic electric power even if no process is performed. The ratio of the basic energy consumption to the total electric energy consumption is large, e.g. 40 to 50 %. In this paper, we newly propose a globally energy-aware (GEA) algorithm to select a server for each process in a cluster. Here, not only the total electric energy consumption of the servers but also the ratio of basic electric energy consumed by servers to the total energy consumption can be reduced. We evaluate the GEA algorithm and show not only the total energy consumption of the servers but also the average execution time of processes are reduced in the GEA algorithm compared with the EA, round-robin (RR), and random (RD) algorithms.\",\n \"Title: Trustworthiness-Based Broadcast Protocols in Wireless Networks\\nYear: 2015\\n\\nAbstract: It is significant to deliver messages to every node in a group to realize the cooperation of the nodes in wireless networks. A node sends a message to the neighbour nodes, each of which forwards the message to the neighbour nodes in flooding protocols. Here, a huge number of messages are transmitted in a network. In multi-point relay (MPR) protocols, only a relay node forwards messages and the other leaf nodes do not forward messages in order to reduce the number of messages transmitted in networks. In this paper, we newly discuss trustworthiness concepts of a neighbour node to broadcast messages. The more trustworthy the node is, the more reliably and efficiently the node can forward messages. Trustworthy neighbour nodes are selected as relay nodes. We propose novel types of trustworthiness-based broadcast (TBR) protocols, TBR1 and TBR2 protocols. In the TBR1 protocol, trustworthy first-neighbour nodes are selected as relay nodes. In the TBR2 protocol, each second-neighbour node is connected to a trustworthy first-neighbour node. In the evaluation, electric energy consumed by a node to send messages from a node to the neighbour nodes is considered as trustworthiness of the neighbour node. We evaluate the TBR1 and TBR2 protocols and show the total electric energy consumed by nodes can be more reduced than the MPR protocol.\",\n \"Title: Optimal Cloud Broker Method for Cloud Selection in Mobile Inter-cloud Computing\\nYear: 2015\\n\\nAbstract: In the next generation of Cloud computing systems (so-called Inter-Cloud), it is expected that multiple Cloud Service Providers (CSPs) will collaborate or cooperate together to form the so-called Cloud Market, with the goal to advertise their services and associate prices to their end users. In this environment, mobile users will be able to better negotiate and select the CSP that better suits their budgetary and technical needs in a more flexible manner. However, despite the benefit of having multiple CSPs to choose from, mobile users will have to cope with several issues, for instance, that of selecting a suitable CSP to handle the incoming service request from the users. To address this problem, this paper proposes an optimal Cloud Broker. The role played by the optimal Cloud Broker is to provide the best possible match for mobile users and CSPs. The Cloud Broker design is formulated by using the framework of Semi-Markov Decision Process (SMDP). Considering the average cost criterion as the optimality criterion, the Value Iteration Algorithm is used to find the optimal Broker policy. Numerical results are presented, demonstrating the effectiveness of our proposed Broker design, in a scenario where a wireless service provider has its own Cloudlet and a Service level Agreement (SLA) has been established with a public CSP to handle the overload occurrences.\",\n \"Title: Synchronization of Peers in Peer-to-Peer Publish/Subscribe Systems\\nYear: 2015\\n\\nAbstract: In distributed systems, a group of multiple processes are cooperating with one another by exchanging messages in networks. In this paper, we consider a peer-to-peer (P2P) model of a topic-based publish/subscribe (P2PPS) system composed of peer processes (peers). Each peer pi can both subscribe a subscription p\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n. S and publish an event message e with a publication e.P, which are specified in terms topics, i.e. Keywords. An event message e is notified to a target peer p\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n whose subscription p\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n.S includes a common keyword with the publication e.P. Each event message e carries a vector e.V = (V\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n, , V\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">m</sub>\\n) of keywords k\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n, , k\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">m</sub>\\n. An event message e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n causally precedes an event message e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n with respect to a subscription S\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n iff e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n causally precedes e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n with respect to the send-receive relation and e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n.V\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">h</sub>\\n <; e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n.V\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">h</sub>\\n for every keyword k\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">h</sub>\\n in the publications e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n.P and e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n.P and the subscription p\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">i</sub>\\n.S. If a pair of event messages e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n and e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n are ordered so that e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n precedes e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n even if e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n does not causally precede e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n, the event messages e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sub>\\n and e\\n<sub xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sub>\\n are unnecessarily ordered. In this paper, every pair of messages are causally delivered to every common target peer by using the linear clock and keyword vector to reduce pairs of messages unnecessarily ordered. We evaluate the keyword vectors in terms of number of messages unnecessarily ordered.\",\n \"Title: A Read-Write Abortion Protocol To Prevent Illegal Information Flow In Role-Based Access Control Systems\\nYear: 2016\\n\\nAbstract: In information systems, a transaction may illegally read data stored in an object which the transaction is not allowed to read is stored in the object. A transaction illegally writes data to an object after issuing illegal read. A transaction suspiciously reads data in a suspicious object whose data is not allowed to flow to some object. A transaction impossibly writes data to an object after issuing suspicious read. In our previous studies, the write-abortion (WA) role-based synchronisation (RBS) and object-based synchronisation (OBS) protocols are proposed where a transaction illegally or impossibly writes data to objects is aborted. In this paper, we newly propose a pair of read-write-abortion (RWA) RBS and OBS protocols where a transaction is aborted only if the transaction issues an illegal read or impossible write to an object. In the evaluation, the execution time of each transaction in RWA protocols is shorter than the WA protocols.\",\n \"Title: Medical Image Analysis by Cognitive Information Systems - a Review.\\nYear: 2016\\n\\nAbstract: This publication presents a review of medical image analysis systems. The paradigms of cognitive information systems will be presented by examples of medical image analysis systems. The semantic processes present as it is applied to different types of medical images. Cognitive information systems were defined on the basis of methods for the semantic analysis and interpretation of information --- medical images --- applied to cognitive meaning of medical images contained in analyzed data sets. Semantic analysis was proposed to analyzed the meaning of data. Meaning is included in information, for example in medical images. Medical image analysis will be presented and discussed as they are applied to various types of medical images, presented selected human organs, with different pathologies. Those images were analyzed using different classes of cognitive information systems. Cognitive information systems dedicated to medical image analysis was also defined for the decision supporting tasks. This process is very important for example in diagnostic and therapy processes, in the selection of semantic aspects/features, from analyzed data sets. Those features allow to create a new way of analysis.\",\n \"Title: A Web Interface For Satellite Scheduling Problems\\nYear: 2016\\n\\nAbstract: Mission planning plays an important role in satellite control systems, especially with increase of number of satellites and more complex missions to be planned. In a general setting, the satellite mission scheduling consists in allocating tasks such as observation, communication, etc. to resources (spacecrafts (SCs), satellites, ground stations). For instance, in ground station scheduling the aim is to compute an optimal planning of communications between satellites and operations teams of Ground Station (GS). Because the communication between SCs and GSs can be done during specific window times, this problem can also be seen as a window time scheduling problem. The required communication time is usually quite smaller than the window of visibility of SCs to GSs, however, clashes are produced, making the problem highly constrained. In this work we present a web interface for solving satellite scheduling problems through various heuristic methods. The web interface enables the users to remotely solve their problem instances through a selection of heuristic methods such as local search methods (Hill Climbing, Simulated Annealing and Tabu Search) and population-based methods (Genetic Algorithms and variants). The user can select to solve previously generated instances by the STK simulation toolkit or generate their own problem instances. The heuristic methods are easily configurable so that users can simulate a variety of scenarios, problem sizes, etc. The execution of the heuristics methods is done at a HPC Cluster infrastructure supporting efficient execution of various solvers. Additionally, the web application allows users to keep track of their executions as well as to share problem instances with other users.\",\n \"Title: Energy-Aware Clusters of Servers for Storage and Computation Applications\\nYear: 2016\\n\\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems like cloud computing systems. In clusters, most application processes like web applications use not only CPU resources but also files and databases. In this paper, we consider storage processes which read and write data in files in addition to computation processes. We propose a PCS model (power consumption model for a storage server) which shows how much electric power a server consumes to perform storage and computation processes. We also propose a CS model (a computation model for storage server) which shows how long it is expected to take to perform storage processes and computation processes. By using the PCS and CS models, we propose a local energy-aware (LEA) algorithm to select a server for a request process in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEA algorithm in terms of total electric energy consumption of the servers. We show the electric energy consumed by servers to perform computation and storage processes can be reduced in the LEA algorithm.\",\n \"Title: Reduction Of Unnecessarily Ordered Event Messages In Peer-To-Peer Model Of Topic-Based Publish/Subscribe Systems\\nYear: 2016\\n\\nAbstract: A distributed system is considered in an event driven model where a state of a process transits on occurrence of an event. In this paper, we discuss a peer-to-peer topic-based publish/subscribe (P2PPS) model where each peer process (peer) can both subscribe and publish event messages. The subscriptions and publications are specified in terms of topics. Each event message e carries a vector e.TV = < tv(1), ..., tv(h)> of topics t(1), ..., t(h) in a system. An event message e(1) causally precedes an event message e(2) with respect to a topic subset T iff not only e(1) causally precedes e(2) but also e(1).tv(j) <= e(2).tv(j) for every topic t(j) in an intersection T of the publications of e(1) and e(2) and the subscription S-i of p(i). A pair of event messages e(1) and e(2) are unnecessarily ordered if e(1).TV <= e(2).TV but e(1) does not causally precede e(2). In this paper, we newly propose a topic-based-causally delivering (TBC) protocol where the linear clock and physical clock are used with topic vectors to reduce the number of pairs of messages unnecessarily ordered. We evaluate the TBC protocol and show the number of pairs of unnecessarily ordered messages is reduced.\",\n \"Title: Energy-Aware Server Selection Algorithms in a Scalable Cluster\\nYear: 2016\\n\\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In this paper, we extend the multi-level power consumption (MLPC) model and the multi-level computation (MLC) model to a server with multiple CPUs. In this paper, we newly propose a totally energy-aware (TEA) algorithm to select a server for a process in a cluster. Here, servers in a cluster are first classified into subclusters. Each subcluster is characterized in terms of the electric power and computation rate. One server is randomly selected in each subcluster. Then, one server is selected so that the expected electric energy is minimum in the selected servers. We evaluate the TEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the TEA algorithm compared with other algorithms.\",\n \"Title: Experimental Results of a Raspberry Pi and OLSR Based Wireless Content Centric Network Testbed Considering OpenWRT OS\\nYear: 2016\\n\\nAbstract: The Content Centric Networks (CCN) replaces the IP narrow waist of the Internet architecture by a content layer. When a node wants to access a piece of content, it sends an Interest packet to the network. The network then, using the name of the content for routing, forwards the Interest to one or more copies of the content object. In this paper, we present the implementation of a OpenWRT OS based testbed for CCN. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor scenario. We transmitted single ICMP flow over UDP. For evaluation we considered hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly and we got low values of delay and jitter.\",\n \"Title: Influential Abortion Probability in a Flexible Read-Write Abortion Protocol\\nYear: 2016\\n\\nAbstract: Data in an object may flow into another object if transactions read and write data in the objects. A transaction illegally reads data in an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the flexible read-write-abortion with role sensitivity (FRWA-R), object sensitivity (FRWA-O), and role safety (FRWA-RS) protocols are proposed to prevent illegal information flow. Here, a transaction aborts with some probability once illegally reading data in an object. The abortionprobability of a transaction depends on the sensitivities of roles which the transaction holds and objects in which the transaction illegally reads data. The safety of a role and object shows how many transactions which hold the role and illegally read data in the object commit or abort after illegally reading data in the object, respectively. Here, safety of a role which increases and decreases by constant values as a transaction holding the role aborts and commits, respectively. Based on the safety concept, we newly propose an influential abortion probability of a transaction where the abortion probability depends on not only roles held by the transaction but also the previous abortion probability. In this paper, we newly propose an FRWA with the influential abortion probability (FRWA-IAP) protocol. In the evaluation, we show a fewer number of transactions abort in the FRWA-IAP protocol than the RWA and FRWA-RS protocols while transactions are more efficiently performed than the WA protocol.\",\n \"Title: An Energy-Efficient Load Balancing Algorithm for Virtual Machine Environments to Perform Communication Type Application Processes\\nYear: 2016\\n\\nAbstract: Scalable, high performance, and fault-tolerant distributed applications are realized with virtual machines in server cluster systems. Application processes are performed on virtual machines in each server. Processing load of virtual machines to perform application processes has to be balanced in a server cluster system to satisfy the application requirements like response time. On the other hand, a server cluster system consumes a large amount of electric energy since multiple servers consume electric energy to perform application processes. It is critical to discuss how to reduce the total electric energy consumption of a server cluster to perform application processes on virtual machines. In our previous studies, the transmission model and power consumption model of a server to perform communication processes on multiple virtual machines are proposed. In this paper, we newly propose the transmission energy consumption laxity based (TECLB) algorithm to allocate communication processes to virtual machines in a server cluster based on the proposed transmission model and power consumption model of a server so that the total energy consumption of a server cluster can be reduced. We evaluate the TECLB algorithm in terms of the total energy consumption of a server cluster and transmission time of each process compared with the basic round-robin (RR) algorithm. The evaluation results show the average total energy consumption of a server cluster is maximumly reduced to 9% of the RR algorithm.\",\n \"Title: An Energy-Aware Migration of Virtual Machines\\nYear: 2016\\n\\nAbstract: We have to reduce the electric energy consumed by servers in a cluster. In our previous studies, types of algorithms to select an energy-efficient server for a request process are proposed. Furthermore, schemes for energy-efficiently migrating a process and replicas of a process are discussed where a process and a replica migrate on a host server to a more energy-efficient guest server in our previous studies. However, it is not easy to realize the migration of processes on types of servers. Virtual machine (VM) technologies are now widely used to support applications with virtual resource service in could computing systems. Here, a virtual machine with application processes can migrate from a host server to another guest server. In this paper, we newly propose an energy-aware migration scheme of virtual machines (EAMV). Here, processes on a virtual machine can migrate to a server which consumes smaller electric energy and can be energy-efficiently performed in a cluster. We implement the EAMV scheme and evaluate the migration scheme in terms of energy consumption of servers and execution time of each process.\",\n \"Title: Examination Of The Implementation Method Of The Cloud Type Virtual Policy Based Network Management Scheme For The Common Use Between Plural Organizations\\nYear: 2016\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the course between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. As the second step of the second phase for the last goal, we examine the implementation method of the cloud type virtual PBNM which can be used by plural organizations in this paper.\",\n \"Title: A Model for Migration of Virtual Machines to Reduce Electric Energy Consumption\\nYear: 2016\\n\\nAbstract: We have to reduce the electric energy consumed by servers in a cluster in order to realize eco-society. Types of algorithms for a request process to select an energy-efficient server in a cluster of servers are proposed in our previous studies. Furthermore, algorithms for energy-efficiently migrating a process on a host server to a more energy-efficient guest server is discussed. Virtual machines are now widely used to support applications with virtual computation service in cloud computing systems. Here, a virtual machine can migrate to a guest server, e.g. which is less loaded. By migrating a virtual machine, application processes performed on the virtual machine can also migrate from a host server to another guest server. In this paper, we newly propose an energy-aware migration algorithm of virtual machines (EAMV). Here, processes on a virtual machine can migrate to a guest server which consumes smaller electric energy and can be energy-efficiently performed in a cluster. We evaluate the EAMV algorithm compared with non-migration algorithms in terms of the total electric energy consumption and execution time of processes. We show the electric energy consumption and average execution time can be reduced in the EAMV algorithm.\",\n \"Title: A Centrality-Based History Prediction Routing Protocol for Opportunistic Networks\\nYear: 2016\\n\\nAbstract: In Opportunistic networks (OppNets), due to high mobility, short radio range, intermittent links, unstable topology, sparse connectivity, to name a few, routing is a very challenging task since it relies on cooperation between the nodes. This paper focuses on using the concept of centrality to alleviate this task. Unlike other nodes in the network, central nodes are those that are more likely to act as communication hubs to facilitate the message forwarding and thereby routing. In this paper, a recently proposed History-Based Prediction Routing protocol (HBPR) for OppNets is re-designed using this concept, yielding the so-called centrality-based HBPR (CHBPR) routing protocol. The proposed CHBPR scheme is evaluated by simulations using the Opportunistic NEtwork (ONE) simulator, showing superior performance compared to HBPR without centrality and Epidemic protocol with centrality, in terms of number of messages delivered at destination and overhead ratio, under varying number of nodes and Time-to-Live.\",\n \"Title: Experimental Results of a Raspberry Pi Based Wireless Mesh Network Testbed Considering TCP and LoS Scenario\\nYear: 2016\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using Raspbian OS. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor environment considering Transmission Control Protocol (TCP) and Line-of-Sight (LoS) scenario. For evaluation we considered throughput, hop count, delay and jitter metrics. The experimental results show that the nodes in the testbed were communicating smoothly.\",\n \"Title: Energy-Aware Algorithms to Select Servers in Scalable Clusters\\nYear: 2016\\n\\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In this paper, we discuss an MLPCM (multi-level power consumption with multiple CPUs) model and an MLCM (multi-level computation with multiple CPUs) model of a server with multiple CPUs. In this paper, we newly propose a modified globally energy-aware (MEA) algorithm to select a server for a process in a cluster of m servers. In the MEA algorithm, a server where a process all is to be performed is selected with computation complexity O(m) if the total electric energy of the servers is minimum. We evaluate the MEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the MEA algorithm compared with other algorithms.\",\n \"Title: Information Flow Control Models in Peer-to-Peer Publish/Subscribe Systems\\nYear: 2016\\n\\nAbstract: A publish/subscribe (PS) model is an event-driven model of a distributed system. In this paper, we consider a peer-to-peer (P2P) type of PS model where each peer (process) can publish and subscribe events. Here, a peer publishes an event message and then the event message is notified to a target peer which is interested in the event. Publications and subscriptions are specified in terms of topics as discussed in topic-based PS systems. In this paper, we newly discuss a topic-based access control (TBAC) model to prevent illegal information flow among peers in PS systems. Here, an access right is a pair \\\"t, op\\\" of a topic t and an operation op which is publish or subscribe. A peer is allowed to publish an event message with topics and subscribe topics only if the topics are granted to the peer. An event message e is notified to a peer pi if the publication of e and subscription of pi include some common topic. If a peer pi publishes an event message e2 after receiving an event message e1, the event message e2 may bring the event of e1, which the peer pi is not allowed to publish. Here, information in the peer pi illegally flow to another peer. We define the legal flow relation among the peers. Then, we newly propose a subscription-based synchronization (SBS) protocol to prevent illegal information flow. Here, a notification is banned if the notification may cause illegal information flow. We evaluate the SBS protocol in terms of number of notifications banned.\",\n \"Title: The Extended Power Consumption Model to Perform Computation Type Application Processes on Virtual Machines\\nYear: 2016\\n\\nAbstract: Scalable and high performance server cluster systems like cloud computing systems are equipped with virtual machines to efficiently utilize server resources. On the other hand, a large amount of electric energy is consumed in a server cluster system since multiple servers consume electric energy to perform application processes on virtual machines. In order to design and implement an energy-aware server cluster system, the computation model of a virtual machine and power consumption model of a server have to be defined. In our previous studies, we proposed the power consumption model of a server and computation model of a virtual machine to perform application processes on virtual machines. However, the proposed power consumption model and computation model does not consider the change of the clock frequency of each core in a server. In this paper, we consider the change of the clock frequency of each core in a server. Then, we newly proposed the extended power consumption model of a server and computation model of a virtual machine to perform computation type application processes.\",\n \"Title: Scalable Group Communication Protocols in the Peer-to-Peer Model of Topic-Based Publish/Subscribe Systems\\nYear: 2016\\n\\nAbstract: A distributed system is considered in an event-driven model composed of processes which are sequences of events. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe system (P2PPS model) where each peer process (peer) can both subscribe interesting topics and publish event messages. Since each peer can both publish and receive event messages, a peer may publish an event message e1 after receiving an event message e2. In the P2PPS system, event messages have to be notified to every common target peer in the causal order. In the TBC (topicbased causally delivery) protocol, event messages are causally delivered by taking advantage of physical time in addition to linear time and topic vector. Physical time is used to reduce pairs of event messages unnecessarily ordered. In this paper, we discuss the relation among the clock offset and delay time in the evaluation.\",\n \"Title: A Model for Energy-Aware Migration of Virtual Machines\\nYear: 2016\\n\\nAbstract: In order to realize eco-society, we have to reduce the electric energy consumed by servers in a cluster in addition to satisfying performance requirements. Virtual machines are now widely used to support applications with virtual computation service in clusters like cloud computing systems. Here, a virtual machine on a host server can migrate to a guest server while processes are being performed on the virtual machine. For example, if the host server of a virtual machine is heavily loaded and a guest server is less loaded, the virtual machine migrates to the guest server. In our previous studies, the EAMV (Energy-Aware Migration of Virtual machines) algorithm is proposed where a virtual machine migrates to a guest server which is expected to consume smaller electric energy to perform processes on the virtual machines. Here, the termination time of each process on each virtual machine is estimated. It is not easy to obtain the state of each process and take time to calculate the expected termination time. In this paper, a virtual machine is considered to be a unit of computation. Termination time of a virtual machine, i.e. time when every process is to terminate on the virtual machine'C is estimated by considering the virtual machines.\",\n \"Title: An Eco Model of Process Migration with Virtual Machines\\nYear: 2016\\n\\nAbstract: It is critical to reduce the electric energy consumed by servers in clusters. In cloud computing systems, computation resources like CPU, memory, and storages are virtualized so that applications can use the resources without being conscious of which physical servers supports which service. Virtual machine technologies are now used to support applications with virtual computation service. Virtual machines are used to perform application processes issued by clients. More importantly, virtual machines can migrate from a host server to a guest server while processes are being performed on the virtual machines. In this paper, we take advantage of migration technologies of virtual machines to reduce the electric energy consumed by servers in a cluster. By using the virtual machines, we propose an energyaware migration model of processes to decide to which virtual machine a process issued by a client is allocated and which virtual machine migrates to another energy-efficient server in order to reduce the electric energy consumption.\",\n \"Title: Power Control Scheme for Underlay Approach in Cognitive Radio Networks\\nYear: 2016\\n\\nAbstract: In this paper, a conflict-graph based power control scheme for spectrum underlay in cognitive radio networks is proposed, which helps avoiding the interference and saving power when the primary and secondary users share the same channel simultaneously. Simulations results using the OMNet++ simulator are provided, showing the effectiveness of the proposed approach in terms of number of users in the network, interference imposed by the secondary users on the primary users, Signal to Interference plus Noise Ratio (SINR), and power saving.\",\n \"Title: Performance Analysis of WMNs by WMN-GA Simulation System for Different WMN Architectures and TCP Congestion-Avoidance Algorithms Considering Uniform Distribution\\nYear: 2016\\n\\nAbstract: In this paper, we evaluate the performance of two Wireless Mesh Networks (WMNs) architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3, Distributed Coordination Function (DCF) and Optimized Link State Routing (OLSR). We compare the performance for Transmission Control Protocol (TCP) Tahoe, Reno and NewReno for uniform distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for both WMN architectures, the PDR values of TCP congestion-avoidance algorithms are almost the same. For Hybrid WMN architecture, the throughput of TCP Reno is better than other algorithms. However, for I/B WMN, the throughput of TCP Tahoe is higher than other algorithms. The delay and jitter of TCP NewReno are a little bit lower compared with other algorithms. The I/B WMN architecture, the fairness index of TCP congestion-avoidance algorithms is almost the same.\",\n \"Title: Selection Algorithms to Select Energy-Efficient Servers for Storage and Computation Processes\\nYear: 2016\\n\\nAbstract: It is now critical to reduce electric energy consumed by servers in a cluster, especially scalable systems like cloud computing systems. In a cluster of servers, most application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the power consumption MLPCS model and computation MLCMS model are proposed. Ways to energy-efficiently perform processes which use either CPU or storages are discussed in a cluster of servers. In this paper, we consider a more general type of process which does both the computation and accesses to storages. By using the MLPCMS and MLCMS models, we propose LEAS and GEAS algorithms to select servers to perform processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the algorithms in terms of total electric energy consumption of the servers and average execution time of the processes. We show the electric energy consumed by servers can be reduced in the LEAS and GEAS algorithms.\",\n \"Title: A Neural Network Based User Identification For Tor Networks: Comparison Analysis Of Different Activation Functions Using Friedman Test\\nYear: 2016\\n\\nAbstract: In this paper, we present the application of Neural Networks (NNs) for user identification in Tor networks. We used the Back-propagation NN and constructed a Tor server, a Deep Web browser (Tor client) and a Surface Web browser. Then, the client sends the data browsing to the Tor server using the Tor network. We used Wireshark Network Analyzer to get the data and then used the Back-propagation NN to make the approximation. For evaluation we considered Number of Packets (NoP) metric and activation function. We analyze the data using Friedman test. From the results, we adopt null hypothesis H-0 since p < 0.05 for all activation functions. However, the softsign/x has the smallest p-value among activation functions. Therefore, it is better to use softsign/x for bad user identification in Tor networks.\",\n \"Title: Multi-level Power Consumption and Computation Models and Energy-Efficient Server Selection Algorithms in a Scalable Cluster\\nYear: 2016\\n\\nAbstract: It is critical to reduce the electric energy consumed in information systems, especially server clusters. In ourprevious studies, the MLPCM (multi-level power consumption with multiple CPUs) and MLCM (multi-level computation with multiple CPUs) models are proposed with server selection algorithms. In the server selection algorithms, a server is selected to perform a process issued by a client by estimating the electric energy consumption by simulating the execution of every current process. However, it takes time to collect the state of processes performed on each server and estimate the termination time of the processes. In this paper, we propose a simple energy-efficient (PEA) algorithm to select server where only state information on number of processes on each serveris used. We evaluate the PEA algorithm and show not only the total electric energy consumption of the servers but also the average execution time of processes are reduced in the PEA algorithm compared with other algorithms.\",\n \"Title: Experimental Results of a Raspberry Pi Based WMN Testbed in Indoor Environment: A Comparison Study of LoS and NLoS Scenarios\\nYear: 2016\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers, because of their potential use in several fields such as collaborative computing and communications. In this paper, we present the implementation of a testbed for WMNs using OpenWRT OS. We analyze the performance of Optimized Link State Routing (OLSR) protocol in an indoor environment considering Line-of-Sight (LoS) and Non Line-of-Sight (NLoS) scenarios. For evaluation we considered throughput, Packet Delivery Ratio (PDR), hop count, delay and jitter metrics. The experimental results show that the performance of the testbed was better for LoS scenario. Also, the nodes in the testbed were communicating smoothly.\",\n \"Title: The Improved Redundant Delay Time-Based (IRDTB) Algorithm to Perform Computation Type Application Processes in Heterogeneous Server Clusters\\nYear: 2016\\n\\nAbstract: In fault-tolerant information systems, application processes have to be reliably performed in presence of server faults. Server cluster systems are widely used to realize not only high performance but also fault-tolerant service. In order to reliably perform application processes, multiple replicas of each application process are performed on multiple servers in a server cluster system. On the other hand, the larger amount of electric energy is consumed in a server cluster system since multiple replicas of each application process are performed on multiple servers. The redundant delay time based (RDTB) algorithm is discussed to select multiple servers to redundantly perform each application process in a homogeneous server cluster so that the total energy consumption of the server cluster can be reduced. In a homogeneous cluster, every server follows the same computation model and power consumption model. On the other hand, servers follow different types of computation models and power consumption models in a heterogeneous server cluster. Hence, a load balancer cannot precisely estimate the processing load and energy consumption of each server in a heterogeneous server cluster by the RDTB algorithm. In this paper, we propose an improved RDTB (IRDTB) algorithm to select multiple servers for redundantly performing each application process so that the total energy consumption of a server cluster and response time of each process in a heterogeneous server cluster can be reduced. We evaluate the IRDTB algorithm compared with the RDTB algorithm in a heterogeneous server cluster. In the evaluation, we show the average total energy consumption of a heterogeneous server cluster in the IRDTB algorithm can be reduced maximum 44% of the RDTB algorithm.\",\n \"Title: Subscription Initialization (SI) Protocol to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems\\nYear: 2016\\n\\nAbstract: In a peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer (process) caP2P) typen be a publisher and subscriber. Here, a peer publishes an event message and then the event message is notified to a target peer which is interested in the event message. Publications and subscriptions are specified in terms of topics. In the topic-based access control (TBAC) model proposed in our previous studies, only a peer granted publication and subscription access rights is allowed to publish event messages with publication topics and subscribe events, respectively. In our previous studies, the illegal information flow relation among peers is defined and the subscription-based synchronization (SBS) protocol is proposed to prevent illegal information flow. Here, topics carried by event messages are just accumulated in the target peers and notification of event messages which may cause illegal information flow are banned in each target peer. The more number of event messages are published, the more number of event messages are not notified in the system. In this paper, we newly propose a subscription initialization (SI) protocol where topics accumulated in peers are removed to reduce the number of notifications banned. We show the number of notifications banned is reduced in the SI protocol compared with the SBS protocol in the evaluation.\",\n \"Title: Topic-Based Causally Ordered Delivery of Event Messages in a Peer-to-Peer (P2P) Model of Publish/Subscribe Systems\\nYear: 2016\\n\\nAbstract: An event-driven publish/subscribe (PS) model of a distributed system is used in various applications. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based PS system (P2PPS model) where each peer process (peer) can both subscribe interesting topics and publish event messages with topics. In our previous studies, we propose the TBC (topicbased causally delivery) protocol an homogeneous networks where maximum delay time between every pair of peers is same. Here, a pair of event messages are checked if the event messages are related in the topic vector and are causally delivered by taking advantage of physical time and linear time. In this paper, we consider a system where peers are interconnected in heterogeneous networks. Here, maximum delay time between every pair of peers is not same. We propose a heterogeneous TBC (HTBC) protocol where event messages are TBC-causally delivered to target peers in heterogeneous network. We evaluate the HTBC protocol and show the number of pair of event messages unnecessarily ordered is reduced in the HTBC protocol.\",\n \"Title: An Energy-Efficient Routing Protocol for Infrastructure-Less Opportunistic Networks\\nYear: 2016\\n\\nAbstract: In this paper, an energy-aware version of a recently proposed History-Based Prediction for Routing (HBPR) protocol for opportunistic networks (OppNets) called energy-efficient HBPR (AEHBPR) is proposed, which saves the energy consumption by avoiding unnecessary packets transmission in the network and by clearing the buffer of nodes carrying the copies of the already delivered packets. The proposed AEHBPR is simulated using the ONE simulator, using synthetic and real mobility traces, showing a superior performance compared to HBPR and AEProphet, in terms of average remaining energy, number of dead nodes, number of delivered messages, and overhead ratio, where AEProphet is the ProPHet routing protocol for OppNets, on which the same energy-aware mechanism has been implemented.\",\n \"Title: Performance Analysis of a Genetic Algorithm Based System for Wireless Mesh Networks Considering Weibull Distribution, DCF and EDCA\\nYear: 2016\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for Weibull distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for I/B WMN, the throughput of both MAC protocols is higher than Hybrid WMN. The delay and jitter of both architectures are almost the same. However, for 10 flows, the delay and jitter of I/B WMN is a lower compared with Hybrid WMN. The fairness index is a almost the same for both WMN architectures.\",\n \"Title: Design and Evaluation of Algorithms to Energy-Efficiently Select Servers for Storage and Computation Processes\\nYear: 2016\\n\\nAbstract: It is now critical to reduce electric energy consumed in a cluster of servers, especially scalable systems like cloud computing systems. In clusters, most application processes like web applications use not only CPU but also storages like databases. In this paper, we consider storage processes which read and write data in files in addition to computation processes. We propose an MLPCMS (power consumption model for a storage server) model which shows how much electric power a server consumes to perform storage and computation processes. We also propose an MLCMS (computation model for a storage server) model which shows the expected execution time of storage and computation processes. By using the MLPCMS and MLCMS models, we propose a GEAS (globally energy-aware server with storage processes) algorithm to select servers to perform computation and storage processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the GEAS algorithm in terms of total electric energy consumption of the servers. We show the electric energy consumed by servers can be reduced in the GEAS algorithm.\",\n \"Title: Energy-Aware Analysis of Synchronizing a Groupware Calendar\\nYear: 2016\\n\\nAbstract: With the fast development in Internet and Mobile technologies, we are witnessing a proliferation of applications that support online collaborative group work. Such applications offer many advantages as compared to traditional web-based online collaborative learning, the most salient feature being the ability to work not only geographically distributed but also on the move, anytime and anywhere. Such applications in the very recent past used to offer lightweight client applications, leaving the burden of the application logics to the server side applications. However, as mobile devices are each time more powerful in terms of computing and storage capacity, client applications at mobile device are each time more complex and heavy so that members of the group could be able to work both offline and online, which arises when members of the group use smartphones and can eventually run out of Internet connection from time to time, or simply want to develop some activities locally. This comes to the price of wasting the battery in shorter time and thus impeding the collaborative work for longer time intervals. Due to this reason, researchers and developers are interested to develop sophisticated mobile applications under energy-aware requirements. In this work we analyse the energy efficiency of a group calendar that offers 1) information sharing among all of members of the group, 2) synchronisation among local calendars of members and global group calendar, 3) conflict resolution through a voting system, 4) awareness of changes in the entries (tasks, members, events, etc.) of the calendar and 5) sharing of calendars among different groups. In particular, we analyse the energy efficiency due to the synchronisations mechanisms employed by a group calendar as synchronisation is among most compute intensive and time consuming tasks. Our study sheds light on the need of implementing various synchronisation mechanisms from lightweight synchronisation to full synchronisation and their applications according to energy profile of the mobile device.\",\n \"Title: Personalized cryptography in cognitive management.\\nYear: 2017\\n\\nAbstract: One of the existing problems of information management is an information security. In this aspects one of possible solution is divide information between a group of persons authorized to manage this information. Information sharing processes allow to protect the information from disclosure. In this paper, the process of division of the information has been enhanced by biometric identification stage. Secure information processes with biometric identification are used to manage very important and strategic data. This paper presents the questions of personal cryptography understood as a combination of the tasks of classifying information and biometric techniques used for this kind of tasks. The techniques of biometric data marking are present on the examples of data division and sharing protocols, expanded by the stages of personal identification and verification. This kind of solutions is presented for the tasks of dividing appropriately the shared secret information. Moreover, we shall present the management process of shadow sets, i.e., of parts of the divided, secret information. The processes of secret data management are refer to tasks of cognitive management, understood as management executed on the basis of understanding the meaning of the processed data.\",\n \"Title: An energy-aware algorithm to migrate virtual machines in a server cluster.\\nYear: 2017\\n\\nAbstract: In order to realise eco-society, we have to reduce the electric energy consumed by servers in a cluster in addition to satisfying performance requirements. Virtual machines are now widely used to support applications with virtual computation service in clusters of servers. Here, a virtual machine on a host server can migrate to a guest server while processes are being performed on the virtual machine. In this paper, we propose an energy-aware migration of virtual machines EAMV algorithm where not only a virtual machine is selected to perform a process issued by a client but also a virtual machine migrates to a guest server which is expected to consume smaller electric energy to perform processes on the virtual machine. In the evaluation, we show the total electric energy consumption of servers and the average execution time of processes can be reduced in the EAMV algorithm compared with non-migration algorithms.\",\n \"Title: Effect of Node Density and Node Movement Model on Performance of a VDTN.\\nYear: 2016\\n\\nAbstract: In this paper, we evaluate the effect of node density and node movement model in a many-to-one communication in a Vehicular Delay Tolerant Network (VDTN). Seven groups with three stationary sensor nodes sense the temperature, humidity and wind speed and send these data to a stationary destination node that collect them for statistical and data analysis purposes. Vehicles moving in Tirana city roads during the opportunistic contacts will exchange the sensed data to destination node. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. For the simulations we considered two different scenarios where the distance of the source nodes from the destination is short and long. The performance is analyzed for three routing protocols for delivery probability and average latency metrics. For both scenarios the effect of node density and node movement model is evaluated. The simulation results show that the increase of node density increases the delivery probability for all protocols and both scenarios, and better results are achieved when shortest-path map-based movement model is used.\",\n \"Title: Energy-aware Migration of Virtual Machines in a Cluster.\\nYear: 2016\\n\\nAbstract: In order to realize eco-society, we have to reduce the electric energy consumed by servers. Virtual machines are now widely used to support applications with virtual computation service in server clusters. Here, a virtual machine can migrate to a guest server while processes are being performed. In the EAMV algorithm we previously proposed, the termination time of each process on each virtual machine has to be estimated. However, it is not easy to obtain the state of each process and takes time to calculate the expected termination time. In this paper, we newly propose a virtual machine migration (VMM) algorithm where termination time of each virtual machine is estimated without considering each process. We evaluate the VMM algorithm and show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the VMM algorithm compared with non-migration algorithms. The VMM algorithm is simpler than the EAMV algorithm\",\n \"Title: An Energy-efficient Migration Model of Processes with Virtual Machines in a Server Cluster.\\nYear: 2016\\n\\nAbstract: In cloud computing systems, computation resources like CPU and storages are virtualized. Virtual machines are now widely used to support applications with virtual computation service and to perform application processes. Furthermore, virtual machines can migrate from a host server to a guest server while processes are being performed on the virtual machines. We have to reduce electric energy consumption of servers in server clusters. In this paper, we take advantage of the migration technologies of virtual machines to reduce the electric energy consumed by servers. We propose a simple virtual machine migration (SVM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. We show the total electric energy consumption of the servers can be reduced in the SVM algorithm.\",\n \"Title: An Energy-efficient and Reliable Protocol in Wireless Networks.\\nYear: 2016\\n\\nAbstract: In recent years, wireless ad-hoc networks which do not use network infrastructure are getting more important in various applications like vehicle-to-vehicle (V2V) networks. Especially, it is easy for nodes to communicate with one another without network infrastructure like access points and base stations. Here, ad-hoc routing protocols are needed to deliver messages to destination nodes. In wireless ad-hoc networks, neighbor nodes with which each node can directly communicate may be changed, e.g due to movement of nodes and faults of nodes. Besides, since nodes in ad-hoc networks work with their electric batteries, it is required to reduce electric energy consumed by nodes to send and receive messages. It is difficult to always find a best route to a destination node due to complex parameters like bandwidth and message loss ratio. In this paper, we newly propose a reliable one-to-one communication protocol named TBAH (Trustworthiness-Based Ad-Hoc communications) protocol where routes to the destination nodes are found by using the fuzzy logic in wireless networks.\",\n \"Title: Comparison Analysis by WMN-GA Simulation System for Different WMN Architectures, Normal and Uniform Distributions, DCF and EDCA Functions.\\nYear: 2016\\n\\nAbstract: Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this paper, we evaluate the performance of two WMN architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) for normal and uniform distributions of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for normal distribution, the throughput of I/BWMNis higher than Hybrid WMN architecture. For uniform distribution, in case of I/B WMN, the throughput of EDCA is a little bit higher than Hybrid WMN. However, for Hybrid WMN, the throughput of DCF is higher than EDCA. For normal distribution, the delay and jitter of Hybrid WMN is lower compared with I/B WMN. For uniform distribution, the delay and jitter of both architectures are almost the same. However, in the case of DCF for 20 flows, the delay and jitter of I/B WMN is a lower compared with Hybrid WMN. In normal distribution case, the fairness index of 10 and 20 flows is higher than 30 flows for both WMN architectures. For I/B architecture the fairness index of DCF is higher than EDCA. However, for Hybrid WMN, the fairness index of EDCA is higher than DCF. For uniform distribution, the fairness index of 10 flows is higher than other flows for both WMN architectures.\",\n \"Title: Energy-aware Server Selection Algorithms for Storage and Computation Processes.\\nYear: 2016\\n\\nAbstract: Application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the algorithms to select a server in a cluster are proposed to energy-efficiently perform processes which use either CPU or storages. In this paper, we consider a more general type of process which does both the computation and accesses to storages. In this paper, we newly propose LEAG and GEAG algorithms to select servers to perform general processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEAG and GEAG algorithms in terms of total electric energy consumption of the servers and average execution time of the processes. We show the electric energy consumed by servers can be reduced in the LEAG and GEAG algorithms.\",\n \"Title: Simple Energy-efficient Server Selection Algorithm in a Scalable Cluster.\\nYear: 2016\\n\\nAbstract: It is critical to reduce the electric energy consumed in server clusters. In our previous studies, the MLPCM and MLCM models are proposed with LEA and MEA server selection algorithms. Here, a server is selected to perform a process by estimating the termination time of every current process. However, it takes time to collect the state of each process and estimate the termination time of each process. In this paper, we propose a simple energy-aware (PEA) algorithm to select a server where only state information on number of processes on each server is used. In the evaluation, we show the computation complexity of the PEA algorithm is O(1), smaller than the other algorithms while the total electric energy consumption of the servers of the PEA algorithm is almost the same as the MEA algorithm and is smaller than the others.\",\n \"Title: Topic-based Synchronization (TBS) Protocols to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems.\\nYear: 2016\\n\\nAbstract: In a peer-to-peer type of topic-based publish/subscribe (P2PPS) model, each peer (process) can publish an event message and receive an event message in which the peer is interested. Subscription of a peer and publication of an event message are specified in terms of topics. In the topic-based access control (TBAC) model proposed in our previous studies, only a peer granted publication and subscription rights is allowed to publish event messages with publication topics and to subscribe events, respectively. In our previous studies, the subscription-based synchronization (SBS) and subscription initialization SBS (SI-SBS) protocols are proposed where notifications which may cause illegal information flow are banned to prevent illegal information flow. It is checked whether or not an illegal information flow to occur in terms of subscription and publication rights granted to each peer. However, even some legal notifications are banned while no illegal event message is notified. In this paper, we newly propose a topic-based synchronization (TBS) and subscription initialization TBS (SI-TBS) protocols where only topics which each peer manipulates are considered. We show the number of notifications banned is reduced in the TBS and SI-TBS protocols compared with the SBS and SI-SBS protocols in the evaluation.\",\n \"Title: Energy-Efficient Quorum Selection Algorithm for Distributed Object-Based Systems.\\nYear: 2017\\n\\nAbstract: Distributed applications are composed of multiple objects and each object is replicated in order to increase reliability, availability, and performance. On the other hand, the larger amount of electric energy is consumed in a system since multiple replicas of each object are manipulated on multiple servers. In this paper, the energy efficient quorum selection (EEQS) algorithm is proposed to construct a quorum for each method issued by a transaction in the quorum based locking protocol so that the total electric energy consumption of servers to perform methods can be reduced. We show the total energy consumption of servers, the average execution time of each transaction, and the number of aborted transactions can be reduced in the EEQS algorithm compared with the random algorithm in the evaluation.\",\n \"Title: Energy-Aware Dynamic Migration of Virtual Machines in a Server Cluster.\\nYear: 2017\\n\\nAbstract: Virtual machines are now widely used to support applications with virtual computation service in server clusters. Here, a virtual machine can migrate from a host server to a guest server while processes are being performed. In this paper, we discuss a virtual machine migration approach to reducing the electric energy consumption of servers. In our previous studies, virtual machines are fixed in a cluster. In this paper, we consider a cluster where virtual machines are dynamically created and dropped. We propose a dynamic virtual machine migration (DVMM) algorithm to reduce the total electric energy consumption of servers. We evaluate the DVMM algorithm and show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced compared with other non-migration algorithms.\",\n \"Title: An Energy-Efficient Migration Algorithm of Virtual Machines in Server Clusters.\\nYear: 2017\\n\\nAbstract: Virtual machines are now widely used to support applications with virtual service on computation resources. Furthermore, a virtual machine can migrate from a host server to a guest server while processes are being performed. In this paper, we propose a Simple Energy-aware Migration (SEAM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. Here, the amount of computation to be performed by processes on a virtual machine is simply estimated only by using the number of the processes. We show the total electric energy consumption of the servers can be reduced in the SEAM algorithm compared with non-migration algorithms in the evaluation.\",\n \"Title: A GA-Based Simulation System for WMNs: Performance Analysis for Different WMN Architectures Considering Weibull Distribution, HWMP and TCP Protocols.\\nYear: 2017\\n\\nAbstract: In our previous work, we implemented WMN-GA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we evaluate the performance of Weibull distribution of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. We compare the performance of both architectures. The simulation results show that the PDR for both WMN architectures is almost the same. The throughput of I/B WMN is a little bit higher than Hybrid WMN. The delay of Hybrid WMN is lower than I/B WMN. The fairness index and the remaining energy for both WMN architectures are almost the same.\",\n \"Title: Flexible Synchronization Protocol to Prevent Illegal Information Flow in Peer-to-Peer Publish/Subscribe Systems.\\nYear: 2017\\n\\nAbstract: In the peer-to-peer type of topic-based publish/subscribe (P2PPS) model, each peer (process) can publish event messages and event messages are notified to target peers with no centralized coordinator. Some information of a peer may flow to target peers by publishing an event message. Here, a target peer recognizes an event message to be related with topics which are in a publication of the event message and the peer subscribes. On the other hand, the peer forgets topics which are in a publication of the event message but not in a set of topics which the peer subscribes. We have to prevent illegal information flow to occur by flowing the forgotten topics. In this paper, we newly propose a flexible synchronization (FS) protocol and a relevance concept of topics to prevent illegal information flow to be caused by the forgotten topics. In the FS protocol, even if an event message carries forgotten topics, a peer accepts the event message if the forgotten topics are related with the subscription topics. In the evaluation, the number of illegal information flows decreases in the FS protocol.\",\n \"Title: Simple Energy-Aware Algorithms for Selecting a Server in a Scalable Cluster\\nYear: 2017\\n\\nAbstract: It is critical to reduce the electric energy consumed in server clusters in order to realize eco society. In our previous studies, a server is selected to perform a process by estimating the termination time of every current process and then the electric energy consumption of servers. However, it is not easy and takes time to collect the state of each process and estimate the termination time of each process. In this paper, we propose SLEA (simple locally energy-aware) and SGEA (simple globally energy-aware) algorithms to select a server where only the number of processes on each server is used. In the evaluation, we show the electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the SLEA and SGEA algorithms.\",\n \"Title: Design and Implementation of a Simulation System Based on Deep Q-Network for Mobile Actor Node Control in Wireless Sensor and Actor Networks\\nYear: 2017\\n\\nAbstract: A Wireless Sensor and Actor Network (WSAN) is a group of wireless devices with the ability to sense physical events (sensors) or/and to perform relatively complicated actions (actors), based on the sensed data shared by sensors. This paper presents design and implementation of a simulation system based on Deep Q-Network (DQN) for mobile actor node control in WSANs. DQN is a deep neural network structure used for estimation of Q-value of the Q-learning method. In this work, we implement the proposed simulating system by Rust programming language. We describe the design and implementation of the simulation system, and show some simulation results to evaluate its performance.\",\n \"Title: Algorithms to Energy-Efficiently Select a Server for a General Process in a Scalable Cluster\\nYear: 2017\\n\\nAbstract: Application processes like Web applications use not only CPU but also storages like HDD. In our previous studies, the algorithms to select a server in a cluster are proposed to energy efficiently perform processes which use either CPU or storages. In this paper, we consider a more general type of processes which do both the computation and access to storages. In this paper, we propose a computation model of a server to perform general processes and a pair of LEAG (locally energy-aware) and GEAG (globally energy-aware) algorithms to select servers to perform general processes in a cluster so that the total electric energy consumption of the servers can be reduced. We evaluate the LEAG and GEAG algorithms and show the electric energy consumed by servers and the average execution time of processes can be reduced in the LEAG and GEAG algorithms.\",\n \"Title: Differentiating the Starting Time of Computation Process Replicas in the Improved Redundant Delay Time-Based (IRDTB) Algorithm\\nYear: 2017\\n\\nAbstract: Server cluster systems are widely used to provide not only scalable but also fault-tolerant distributed application services. Each application process has to be reliably performed in presence of server fault to provide reliable application services. One way to reliably perform an application process is that replicas of each application process are performed on multiple servers. However, a larger electric energy is consumed in a server cluster since multiple replicas are performed on multiple servers. In our previous studies, the improved redundant delay time-based (IRDTB) algorithm is proposed to select multiple servers for redundantly and energy efficiently performing computation type application processes in a server cluster. In the IRDTB algorithm, a request process broadcasts to multiple servers and replicas for the request process starts almost at the same time on each server. Here, once a replica successfully terminates on one server, replicas being or to be performed on other servers are meaningless. In this paper, we newly propose an extended IRDTB (EIRDTB) algorithm to furthermore reduce the total energy consumption of a server cluster by forcing meaningless replicas to terminate and differentiating the starting time of each replica. In the EIRDTB algorithm, a request process is serially sent to each server every δ time unit. We evaluate the EIRDTB algorithm in terms of total energy consumption of a server cluster and the average response time of each process compared with the IRDTB algorithm. The evaluation results show the longer inter-request time δ, the smaller amount electric energy is consumed in the EIRDTB algorithm than the IRDTB algorithm.\",\n \"Title: Energy-Aware Virtual Machine Migration Models in a Scalable Cluster of Servers\\nYear: 2017\\n\\nAbstract: In clusters of servers like cloud computing systems, computation resources like CPUs and storages are virtualized. Virtual machines are now widely used to support applications with virtual computation service on computation resources. Application processes are performed on virtual machines independently of which servers of which architectures are used. Furthermore, a virtual machine can migrate from a host server to a guest server while processes are being performed on the virtual machines. In this paper, we take advantage of the migration technologies of virtual machines to reduce the electric energy consumed by servers. We propose a modified simple virtual machine migration (MSVM) algorithm to migrate a virtual machine to another energy-efficient server in order to reduce the electric energy consumption. Here, the amount of computation to be performed by processes on a virtual machine is estimated only by using the number of the processes. We show the total electric energy consumption of the servers can be reduced in the MSVM algorithm compared with non-migration algorithms.\",\n \"Title: A GA-Based Simulation System for WMNs: Performance Analysis for Different WMN Architectures Considering Exponential Distribution, HWMP and TCP Protocols\\nYear: 2017\\n\\nAbstract: In our previous work, we implemented WMNGA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we evaluate the performance of two different distributions of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. We compare the performance of both architectures for exponential distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the PDR for both WMN architectures is almost the same. The throughput of I/B WMN is higher than Hybrid WMN. The delay of I/B WMN is lower than Hybrid WMN. The fairness index of Hybrid WMN is higher than I/B WMN. For I/B WMN architecture, the energy decreases faster than Hybrid WMN.\",\n \"Title: Load Experiment of the Cloud Type Virtual Policy Based Network Management Scheme for the Common Use between Plural Organizations\\nYear: 2017\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, as the progression phase for the last goal, we perform the load experiment of the cloud type virtual PBNM, which can be used by plural organizations.\",\n \"Title: Topic-Based Selective Delivery Of Event Messages In Peer-To-Peer Model Of Publish/Subscribe Systems In Heterogeneous Networks\\nYear: 2017\\n\\nAbstract: In this paper, we discuss a peer-to-peer (P2P) model of a topic-based publish/subscribe (PS) system (P2PPS model) where each peer process (peer) can both subscribe and publish event messages with topics and there is no centralized coordinator. Each peer has to causally deliver event messages in which the peer is interested. In our previous studies, the TBC (topic-based causally delivery) protocol is proposed for a homogeneous synchronous network where maximum delay time between every pair of peers is the same and the maximum clock offset of each peer is the same. In this paper, we propose a heterogeneous TBC (HTBC) protocol where peers are interconnected in heterogeneous networks where maximum delay time between every pair of peers and maximum clock offset of each peer may not be the same. In the evaluation, we show the number of pairs of event messages unnecessarily ordered is reduced in the HTBC protocol.\",\n \"Title: Sensitivity-Based Synchronisation Protocol To Prevent Illegal Information Flow Among Objects\\nYear: 2017\\n\\nAbstract: In information systems, a transaction may illegally read data stored in an object, which the transaction is not allowed to read. A transaction illegally writes data to an object after issuing illegal read. The write-abortion (WA), read-write-abortion (RWA) and flexible RWA (FRWA) protocols to prevent illegal information flow are proposed in our previous papers. In the WA and RWA, a transaction is aborted once issuing an illegal write and illegal read, respectively. In the WA, some reads are meaninglessly performed. In the RWA, some reads are lost. In the FRWA, a transaction is aborted with some probability once issuing illegal read. We newly introduce an object sensitivity concept to decide on the abortion probability. In the evaluation, the execution time of each transaction in the FRWA with object sensitivity is shorter than the WA and more number of reads can be performed than the RWA.\",\n \"Title: Eco Models of Distributed Systems.\\nYear: 2017\\n\\nAbstract: It is critical to reduce electric energy consumed in information systems, especially servers in scalable clusters, in order to realize eco society. In this paper, we take the macro-level approach to reducing the electric energy consumption of servers. Here, we aim at reducing the total energy consumed by a server to perform application processes. First, we discuss power consumption models which give electric power to be consumed by a server to perform application processes. We also discuss computation models of a server which give execution time of application processes. Based on the models, we discuss algorithms to select an energy-efficient server to perform an application process issued by a client. We also discuss algorithms to migrate processes on host servers to more energy-efficient servers by using virtual machines.\",\n \"Title: Load Experiments of the vDACS Scheme in Case of the 600 Connections by 300 Clients.\\nYear: 2017\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, as the progression phase for the last goal, we perform the load experiment of the cloud type virtual PBNM named the vDACS Scheme, which can be used by plural organizations, for applications to the small and medium size scale organization. The number of clients used in an experiment is 600.\",\n \"Title: Energy-Efficient Role Ordering Scheduler.\\nYear: 2017\\n\\nAbstract: In information systems, conflicting methods issued by multiple transactions have to be serialized to keep objects mutually consistent. There are various ways to serialize multiple conflicting transactions like timestamp ordering (TO) and FIFO schemes. In this paper, the energy efficient role ordering (EERO) scheduler is proposed to not only serialize multiple conflicting transactions in the significant order of subjects but also reduce the total energy consumption of servers by omitting meaningless methods.\",\n \"Title: A Simple Energy-Aware Virtual Machine Migration Algorithm in a Server Cluster.\\nYear: 2017\\n\\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where virtual machines with application processes migrate to more energy-efficient servers. In the SEAM algorithm previously proposed, a host server to perform a process and to migrate a virtual machine is selected whose expected electric energy consumption is minimum. In this paper, the SEAM algorithm is improved where a host server is selected with minimum expected electric energy consumed by not only the host server but also the other servers. We show the total electric energy consumption of the servers can be reduced in the improved SEAM (ISEAM) algorithm compared with non-migration algorithms and the SGEA algorithm in the evaluation.\",\n \"Title: An Energy-Aware One-to-one Routing Protocol in Wireless Ad-Hoc Network.\\nYear: 2017\\n\\nAbstract: In wireless ad-hoc networks, messages are exchanged among nodes in wireless communication networks in ad-hoc routing protocols. Here, the electric energy consumed by nodes to send messages has to be reduced. The ESU (Energy-Saving Unicast routing) protocol is proposed in our previous study, where the electric energy consumption of each node can be reduced, but the length of source-destination route, i.e. number of nodes increases. In this paper, we newly propose an EAO (Energy Aware One-to-one routing) protocol to shorten the length of a route and reduce the total electric energy consumption of nodes in a route. In the evaluation, we show the total electric energy consumption of nodes in a source-destination route can be reduced in the EAO protocol compared with other protocols.\",\n \"Title: A GA-Based Simulation System for WMNs: A Comparison Study for Different WMN Architectures Considering Exponential and Weibull Distributions, HWMP and TCP Protocols.\\nYear: 2017\\n\\nAbstract: In our previous work, we implemented WMN-GA system which is based on Genetic Algorithms (GAs) and used it for node placement problem in WMNs. In this paper, we compare the performance of Exponential and Weibull distributions of mesh clients for two WMN architectures considering PDR, throughput, delay, fairness index and energy metrics. For simulations, we used ns-3, Hybrid Wireless Mesh Protocol (HWMP) and TCP. The simulation results show that the PDR for both distributions is almost the same. The throughput of Exponential distribution is a little bit higher than Weibull distribution. The delay of Weibull distribution is lower than Exponential distribution. For Hybrid WMN, the fairness index of Exponential distribution is higher than Weibull distribution. But for I/B WMN, the fairness index of Weibull distribution is higher than Exponential distribution.\",\n \"Title: An Eco Algorithm for Dynamic Migration of Virtual Machines in a Server Cluster.\\nYear: 2017\\n\\nAbstract: Electric energy consumed in server clusters has to be reduced. In our previous studies, the dynamic virtual machine migration (DVMM) algorithm is proposed to reduce the total electric energy consumption of servers. In this paper, we improve the DVMM algorithm to furthermore reduce the electric energy consumption. If an application issues a process to a cluster, a most energy-efficient host server is first selected and the process is performed on a virtual machine on the server. Then, a virtual machine migrates from a host server to a more energy-efficient guest server. In the evaluation, we show not only the total electric energy consumption and active time of servers but also the average execution time of processes can be reduced in the DVMM algorithm compared with other algorithms.\",\n \"Title: Security of Visual Captcha for Authentication Procedures.\\nYear: 2017\\n\\nAbstract: In this paper will be described new idea of security procedures using visual captcha, and dedicated to authentication procedures. In particular will be presented the most important aspects connected with security of visual captcha used in security procedures, implemented in service management solutions in Cloud environment. Services management in Cloud Computing will be connected with application of secure cognitive information and cognitive management systems, supporting management activities and securing data using visual captcha solutions.\",\n \"Title: Evaluation of Flexible Synchronization Protocol to Prevent Illegal Information Flow in P2PPS Systems.\\nYear: 2017\\n\\nAbstract: We consider the peer-to-peer type of topic-based publish/subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. Some information of a peer may flow to target peers by exchanging event messages. Here, the peer forgets topics which are in a publication of the event message but not in the subscription of the peer. In our previous studies, the flexible synchronization (FS) protocol and the relevance concept of topics are proposed. However, it is difficult, maybe impossible for each peer to know about every topic in a system. Each time a peer receives an event message, topics carried by the event message which the peer does not know but are related with subscribed topics are obtained in the peer. Thus, each peer learns and obtains new topics through receiving event messages. In the evaluation, we show the more number of topics each peer can initially subscribe, the fewer number of notifications are banned and the more number of forgotten topics are added to the subscription. However, the advantage obtained by initially including more number of topics decreases as the number of event messages exchanged among peers increases.\",\n \"Title: Multi-Level Power Consumption Model And Energy-Aware Server Selection Algorithm\\nYear: 2017\\n\\nAbstract: Electric power consumed by servers has to be reduced in a cluster in order to realise eco society. We take a macro-level approach to reducing the total electric energy consumption of servers to perform application processes. In this paper, we discuss a Multi-Level Power Consumption (MLPC) model of a server with a multi-thread CPU and a Multi-Level Computation (MLC) model. Based on the MLPC and the MLC models, we newly propose an energy-aware (EA) algorithm to select a server for each process requested by a client in a cluster to reduce the total electric energy consumption of the cluster while satisfying deadline requirements of the processes. We evaluate the EA algorithm and show that not only the total electric energy consumption of servers but also the average execution time of each process are reduced in the EA algorithm compared with the round-robin (RR) and random (RD) algorithms.\",\n \"Title: Algorithms For Energy-Efficient Broadcasting Messages In Wireless Networks\\nYear: 2018\\n\\nAbstract: In order to realize the cooperation of a group of multiple nodes, messages have to be reliably and efficiently delivered to all of them, according to a traditional broadcasting paradigm, by also reducing the electric energy consumed by each involved node. In this paper, we propose three types of energy-efficient broadcast algorithms, namely EEB (energy-efficient broadcast), EEB2 (modified EEB), and AEEB (augmented EEB) whose objective is reducing the total electric energy consumed by nodes. In the EEB algorithm, a wireless link to a farthest child node is truncated until there is no other child node which can forward messages to it in a more energy-efficient way. In the EEB2 algorithm, a link to a farthest child node is truncated if there is another child node which can forward the message to it. In the EEB and EEB2 algorithms, a child node is selected for each parent node. On the other hand, one parent node is selected among possible parent nodes of each child node, which is nearest to the child node in the AEEB algorithm. We evaluate the EEB, EEB2, and AEEB algorithms and show that the total electric energy consumed by nodes can be reduced in the AEEB algorithm.\",\n \"Title: Visual CAPTCHA application in linguistic cryptography.\\nYear: 2018\\n\\nAbstract: This paper presents an idea of linguistic cryptography and linguistic techniques for data analysis. The main aspects are using parts of divided information to reconstruct them. Linguistic techniques dedicated to cryptography, as well as secret splitting and sharing, are very useful to secure all information and all parts of them. Very important aspects of cryptographic algorithms are played by techniques of data division as well as data splitting and information sharing algorithms. Those methods allow the distributed data within a different selected group of secret trustees. In this paper, authors described algorithms of using those methods for linguistic data sharing techniques. In those methods, CAPTCHA analysis plays an important role. All secret parts of information can be written by using any parts of the selected CAPTCHA procedures.\",\n \"Title: Cognitive Approaches for Medicine in Cloud Computing.\\nYear: 2018\\n\\nAbstract: • We proposed a cognitive methods for data description. • Proposed a techniques for secure data in Cloud Computing. • Application of cognitive approaches for medicine was described.\",\n \"Title: Concept of the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\\nYear: 2017\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. The first is the scheme for managing the whole LAN by locating the communication control mechanisms on the path between network servers and clients. The second is the scheme of managing the whole LAN by locating the communication control mechanisms on clients. As the second scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, the explanation about the scheme to manage the specific domain is performed. In this scheme, the scheme to manage the network group of plural organizations is expanded.\",\n \"Title: Interference Aware Metric-Based Routing Protocol in Cognitive Radio Networks.\\nYear: 2017\\n\\nAbstract: Cognitive radio networks (CRNs) are spectrum agile devices capable of changing their communication parameters based on their spectral environment. This capability can be exploited by designing dynamic spectrum access strategies that can utilize the unused spectrum vacated by the licensed users. In this paper, the problem of routing in Cognitive Radio Networks is investigated by exploiting the unoccupied spectrum called Spectrum Opportunities (SOP). An efficient Interference Aware Routing Protocol (IARP) is proposed which can be used to route the data packets between the unlicensed secondary users. The proposed IARP uses an interference aware routing metric (IR) that takes into account the interference in the spectral environment to determine good quality paths between two nodes. The performance of the IARP protocol is evaluated by simulating the CRN under different scenarios. The experimental results show the efficiency of the proposed routing protocol in delivering high throughput and packet delivery ratio with minimum network latency.\",\n \"Title: An Energy Efficient Load Balancing Algorithm Based on the Active Time of Cores.\\nYear: 2017\\n\\nAbstract: Server cluster systems are widely used to realize scalable and high performance computing systems with virtual machine technologies. A large amount of electric energy is consumed in a server cluster system since a server cluster system is composed of large number of servers and multiple servers consume electric energy to perform application processes on multiple virtual machines. In order to design and implement an energy-efficient server cluster system, it is necessary to realize energy-efficient load balancing algorithms. In this paper, the active time-based (ATB) algorithm is proposed to select a virtual machine for each request process so that the total electric energy of a server cluster to perform computation type application processes can be reduced. In the ATB algorithm, it is not necessary to collect a state of every process on every virtual machine to estimate the electric energy of each server. We evaluate the ATB algorithm in terms of the total electric energy of a server cluster compared with the energy consumption laxity based (ECLB) and basic round-robin (RR) algorithms.\",\n \"Title: Performance Evaluation of WMNs by WMN-PSOSA Simulation System Considering Random Inertia Weight Method and Linearly Decreasing Vmax Method.\\nYear: 2017\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the Performance of WMN-PSOSA by conducting computer simulations considering Random Inertia Weight Method (RIWM) and Linearly Decreasing Vmax Method (LDVM). The simulation results show that the LDVM has better performance than RIWM for this scenario.\",\n \"Title: Comparison of Spray and Wait and Epidemic Protocols in Different DTN Scenarios.\\nYear: 2017\\n\\nAbstract: In this paper, we evaluate the performance of Epidemic, Spray and Wait, and their versions with congestion control and Epidemic with TCP in two different set of simulations. In the first set of simulations, we evaluate the effect of network node density for map-based mobility model considering Tirana city map. In the second set of simulations, we compare the effect of mobility model on the network performance by comparing the results of map-based model with RWP mobility model. The performance evaluation metrics are: delivery ratio, hop count, average delay, average buffer occupancy. Simulations are conducted using NS3 simulator. The simulation results show that increase of node density increase also the delivery ratio. The performance using RWP is higher compared with the realistic scenarios because in the realistic scenario the nodes movement is more complex and opportunistic contacts are more rare. The usage of epidemic with TCP leads to high average delay in all scenarios because the need of sending ack packets to the source nodes.\",\n \"Title: Hybrid Replication Schemes of Processes for Fault-Tolerance Systems in Energy-Efficient Server Clusters.\\nYear: 2017\\n\\nAbstract: Application processes have to be not only fault-tolerantly but also energy-efficiently and performance-efficiently performed on servers in a cluster. The more number of replicas of a process are performed on servers, the more reliably and availably the process can be performed. However, the more electric energy is consumed by servers since the more number of servers work to perform the replicas. We make clear software components of replicas of a process. In this paper, we discuss new types of replica groups which are composed of different types of replicas with different software components. In the evaluation, we show the electric energy consumption of servers can be reduced in the replica groups compared with the traditional active and passive types of replication schemes.\",\n \"Title: A Low-Energy Unicast Ad-Hoc Routing Protocol in Wireless Networks.\\nYear: 2017\\n\\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently exchanged among neighboring nodes. In our previous studies, the reactive type ESU (Energy-Saving Unicast routing) and EAO (Energy-Aware One-to-one routing) protocols are proposed. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In this paper, we newly proposed an LEU (Low-Energy Unicast Ad-hoc routing) protocol to overcome the difficulties of the EAO protocol. Here, a neighbor node which has an uncovered neighbor node is selected as a prior node for each node to make a route. In the evaluation, we show the number of nodes in a source-to-destination route can be reduced and a route can be found even in shorter communication range in the LEU protocol compared with the EAO protocol.\",\n \"Title: Classification of Cognitive Service Management Systems in Cloud Computing.\\nYear: 2017\\n\\nAbstract: In this paper will be presented a new classification of cognitive systems dedicated to cloud service management. Especially, this classification will be described with application of cognitive aspects. Semantic description will be dedicated to service management application in the cloud. In particular will be presented the most important aspects of cognitive service management in the cloud and distributed systems. Services management in the cloud can be realized with application of secure semantic idea and cognitive service management solutions.\",\n \"Title: A Simple Migration Algorithm of Virtual Machine in a Server Cluster.\\nYear: 2017\\n\\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where virtual machines with application processes migrate to more energy-efficient servers. We newly propose an ISEAM2 algorithm to select a virtual machine on a host server to perform a process issued by an application and a guest server to which the virtual machine migrates so that the electric energy consumption of the servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and average execution time of processes can be reduced in the ISEAM2 algorithm.\",\n \"Title: A Flexible Synchronization Protocol for Hidden Topics to Prevent Illegal Information Flow in P2PPS Systems.\\nYear: 2017\\n\\nAbstract: We consider the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. Here, event messages on hidden topics which a peer can subscribe but a target peer cannot subscribe are notified to target peers. After an event message e(1) with hidden topics is notified, if a peer publishes another event message e(2), the event message e(2) may be related with the hidden topics. Hence, if the event message is notified to another peer which does not subscribe the hidden topics, illegal information flow occur. In this paper, we newly propose an FS-H (Flexible Synchronization for Hidden topics) protocol where a peer obtains hidden topics in the subscription if the hidden topics are related with the subscription topics. In the evaluation, the fewer number of notifications are banned in the FS-H protocol than the other protocols.\",\n \"Title: Virtual Machine Migration Algorithms to Reduce Electric Energy Consumption of a Server Cluster.\\nYear: 2018\\n\\nAbstract: In this paper, we discuss a virtual machine migration approach to reducing the electric energy consumption of servers. In our previous algorithms, one virtual machine migrates from a host server to a guest server. While the electric energy consumption of servers can be reduced by migrating some number b of processes, there might not be a virtual machine with the same number b of processes on a host server. In this paper, we propose an ISEAM2T algorithm where multiple virtual machines can migrate from a host server to a guest server. Here, multiple virtual machines on a host server are selected so that the total number of processes on the virtual machines can be more easily adjusted to the best number b of processes. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the proposed algorithm.\",\n \"Title: Performance Analysis of Simulation System Based on Particle Swarm Optimization and Distributed Genetic Algorithm for WMNs Considering Different Distributions of Mesh Clients.\\nYear: 2018\\n\\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), calledWMN-PSODGA. We analyze the performance of WMN-PSODGA by computer simulations considering different client distributions. Simulation results show that the WMN-PSODGA has good performance when the client distribution is Normal compared with the case of Exponential distribution.\",\n \"Title: One-to-One Routing Protocols for Wireless Ad-Hoc Networks Considering the Electric Energy Consumption.\\nYear: 2018\\n\\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently delivered to destination nodes by exchanging the messages among neighboring nodes. In our previous studies, the reactive type EAO, LEU, and IEAO protocols are proposed to unicast messages. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In the IEAO protocol, a route can be found even in short communication range. In the forwarding phase, a node p(i) does not necessarily receive an RQ messages which sent by a node p(j) whose level parameter is bigger than p(j) and keeps the information which is contained in the RQ messages. Here, by neglecting superfluous RQ messages, the electric energy consumption of the forwarding phase can be reduced. In this paper, we propose an IEAO2 protocol by improving the IEAO protocol so that the electric energy consumption is reduced in the forwarding phase. In the evaluation, we show the information which each node keeps can be reduced in the IEAO2 protocol compared with other protocols.\",\n \"Title: An Integrated System Considering WLAN and DTN for Improving Network Performance: Evaluation for Different Scenarios and Parameters.\\nYear: 2018\\n\\nAbstract: In this paper, we integrate a Wireless Local Area Network (WLAN) with a Delay Tolerant Network (DTN) to improve the network performance when the network is congested or communication link problems occur. We evaluate the performance under different scenarios for three routing protocols. Simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The simulation results shows that with the increase of the simulation time DTN hosts are in movement for longer time and the probability of the DTN hosts to meet and exchange the data is increased. The usage of DTN improves the performance of the network by sending information with high delivery probability.\",\n \"Title: Eco Migration Algorithms of Processes with Virtual Machines in a Server Cluster.\\nYear: 2018\\n\\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption where a virtual machine with application processes migrates to a more energy-efficient server. We newly propose an ISEAM2 algorithm to select a pair of a virtual machine on a host server to perform a process issued by an application and a guest server to which the virtual machine migrates so that the electric energy consumption of the host and guest servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the ISEAM2 algorithm.\",\n \"Title: Malicious Information Flow in P2PPS Systems.\\nYear: 2018\\n\\nAbstract: We consider the peer-to-peer (P2P) type of topic-based publish/ subscribe (P2PPS) model where each process (peer) can publish and subscribe event messages with no centralized coordinator. An event message e(1) may carry information of another event message e(2) causally preceding e(1), which are denoted by topics. If a peer receiving e(1) is not allowed to subscribe the topics, illegal information flow to the peer occur. In our previous studies, the subscription-based synchronization (SBS), topic-based synchronization (TBS), and flexible synchronization for hidden topics (FS-H) protocols are proposed to prevent illegal information flow. In this paper, we newly consider malicious information flow among peers where a source peer does not give related topics or gives unrelated topics to event messages. If a source peer pi publishes an event message e without including some related topic or with including some unrelated topic, the peer pi is malicious. In this paper, we newly define types of malicious information flow among peers based on a set of topics which every peer can publish and subscribe.\",\n \"Title: Service Management Protocols in Cloud Computing.\\nYear: 2018\\n\\nAbstract: In this paper will be presented a description of service management protocols for Cloud infrastructure. Especially, presented solutions will be dedicated to Cloud and Fog Computing. The main idea will be described with application of semantic aspects, dedicated to service management application. Services management protocols in the cloud and in the fog can be realized with application of secure and strategic methods.\",\n \"Title: Performance Evaluation of WMN-PSOSA Considering Four Different Replacement Methods.\\nYear: 2018\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering four different replacement methods. The simulation results show that LDIWM have better performance than CM, RIWM and LDVM replacement methods.\",\n \"Title: Design and Implementation of a Hybrid Intelligent System Based on Particle Swarm Optimization and Distributed Genetic Algorithm.\\nYear: 2018\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We evaluate WMN-PSODGA by computer simulations. The simulation results show that the WMN-PSODGA has good performance when the number of GA islands is 64.\",\n \"Title: Application of Fuzzy Logic for Improving Human Sleeping Conditions in an Ambient Intelligence Testbed.\\nYear: 2018\\n\\nAbstract: Ambient Intelligence (AmI) deals with a new world of ubiquitous computing devices, where physical environments interact intelligently and unobtrusively with people. AmI environments can be diverse, such as homes, offices, meeting rooms, schools, hospitals, control centers, vehicles, tourist attractions, stores, sports facilities, and music devices. In our previous work, we presented the implementation and evaluation of actor node for AmI testbed. In this paper, we introduce the implementation of the AmI testbed. We present the simulation results of the proposed Fuzzy-based Sleeping Condition System (FSCS) considering four parameters: room lighting, humidity, temperature and noise. The simulation results show that different parameters have different effects on human sleeping condition.\",\n \"Title: Improved Energy-Efficient Quorum Selection Algorithm by Omitting Meaningless Methods.\\nYear: 2018\\n\\nAbstract: Distributed applications are composed of multiple objects and each object is replicated in order to increase reliability, availability, and performance. On the other hand, the larger amount of electric energy is consumed in a system since multiple replicas of each object are manipulated on multiple servers. In our previous studies, the energy efficient quorum selection (EEQS) algorithm is proposed to construct a quorum for each method in the quorum based locking protocol so that the total electric energy of servers to perform methods can be reduced. In this paper, the improved energy efficient quorum selection (IEEQS) algorithm is proposed to furthermore reduce the total electric energy of servers by omitting meaningless methods. Evaluation results show the total electric energy of servers, the average execution time of each transaction, and the number of aborted transactions can be reduced in the IEEQS algorithm than the EEQS algorithm.\",\n \"Title: Influence of Management and Sharing Protocols for Decision Making Processes in Cloud Computing.\\nYear: 2018\\n\\nAbstract: In this paper will be evaluated influence of proposed sharing technologies for efficiency of decision making procedures in particular sectors or companies. Especially, such evaluation will be done for Cloud and Fog based procedures and services. Presented research justified the great importance of proper selection of efficient management services for particular task or distributed operations. Especially, presented solutions will be dedicated to Cloud and Fog Computing. The main idea will be describe with application of semantic aspects, dedicated to service management application. Services management protocols in the cloud and the fog can be realized with application of secure important and strategic idea.\",\n \"Title: A Tree-Based Model of Energy-Efficient Fog Computing Systems in IoT.\\nYear: 2018\\n\\nAbstract: A huge number and various types of devices like sensors and actuators are interconnected with clouds of servers in the IoT (Internet of Things). Here, a large volume of data created by sensors have to be efficiently transmitted and processed and actions have to be efficiently delivered to actuators at an opportune time. In order to reduce the delay time and increase the performance, data and processing are distributed to not only servers but also fog nodes in fog computing systems. On the other hand, the total electric energy consumed by fog nodes increases since a huge number of fog nodes are interconnected. In this paper, we newly propose a tree-based fog computing model to deploy processes and data to fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the tree-based model is smaller than the cloud model where processes and data are centralized.\",\n \"Title: Performance Evaluation of WMN-PSOSA Considering Exponential and Weibull Distributions.\\nYear: 2018\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem in WMNs, calledWMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering Exponential and Weibull distributions. Simulation results show that WMN-PSOSA performs better for Weibull distribution compared with the case of Exponential distribution.\",\n \"Title: Energy-Efficient Process Replication by Forcing Meaningless Replicas to Terminate in Virtual Machine Environment.\\nYear: 2018\\n\\nAbstract: Server cluster systems equipped with virtual machines are widely used to provide various types of reliable application services. Especially, multiple replicas of each application process can be redundantly performed on multiple virtual machines to realize reliable application services. On the other hand, a large amount of electric energy is consumed in a server cluster since multiple replicas of each application process are performed on multiple virtual machines. In this paper, the improved redundant energy consumption laxity based (IRECLB) algorithm is newly proposed to reduce the total electric energy consumption of a server cluster for redundantly performing each application process by forcing meaningless replicas to terminate. We evaluate the IRECLB algorithm in terms of the total electric energy consumption of a server cluster and the average response time of each process compared with the redundant energy consumption laxity based (RECLB) algorithm previously proposed.\",\n \"Title: An Eco IDMMV Migration Algorithm of Dynamic Virtual Machines in a Server Cluster.\\nYear: 2018\\n\\nAbstract: Processes on virtual machines can migrate from a host server to a guest server without suspending the processes by migrating the virtual machines. In our previous studies, the total electric energy consumed by servers and the average execution time of processes are shown to be reduced by migrating virtual machine to a more energy-efficient server. In this paper, we propose a DMMV2 (Dynamic Migration of Multiple Virtual machines 2) algorithm where multiple virtual machines migrate among servers. In the evaluation, we show not only the total electric energy consumption and total active time of servers but also the average execution time of processes can be reduced in the DMMV2 algorithm compared with other algorithms.\",\n \"Title: Unicast Routing Protocols to Reduce Electric Energy Consumption in Wireless Ad-Hoc Networks.\\nYear: 2018\\n\\nAbstract: In wireless ad-hoc networks, messages have to be energy-efficiently exchanged among neighboring nodes. In our previous studies, the reactive type EAO (Energy-Aware One-to-one routing) and LEU (Low-Energy Unicast Ad-hoc routing) protocols are proposed to unicast messages to the destination node. In the EAO protocol, the total electric energy of nodes and delay time from a source node to a destination node can be reduced compared with the ESU and AODV protocols. However, a source-to-destination route may not be found if the communication range of each node is shorter. In this paper, we newly proposed an IEAO (Improved Energy-Aware One-to-one routing) protocol to overcome the difficulties of the EAO protocol. Here, after a shortest route is found to the destination node, a more energy-efficient prior node is found in nearest neighbor of each node starting from the destination node. In this paper, a neighbor node which has an uncovered neighbor node is selected as a prior node for each node to make a route. In the evaluation, we show the number of nodes in a source-to-destination route can be reduced and a route can be found even in shorter communication range in the IEAO protocol compared with the LEU and EAO protocols.\",\n \"Title: A Simple Algorithm to Select Energy-Efficient Servers for Storage and Computation Processes.\\nYear: 2018\\n\\nAbstract: In application processes like Web and databases, files and databases are manipulated on servers. Thus, both CPU and storage resources are used to perform application processes. In this paper, we propose a computation model to give the expected termination time of each application process. Here, computation operations and storage operations of a process are integrated into virtual computation steps. Then, we propose an SGEAG (Simple Globally-Energy-Aware for General processes) algorithm to select a server to perform a new process issued by a client, which is expected to consume the minimum electric energy to perform not only the new process but also every current process. In the evaluation, we show the electric energy consumed by servers and the average execution time of processes can be more reduced in the SGEAG algorithm than the other algorithms.\",\n \"Title: An Energy-Efficient Model of Fog and Device Nodes in IoT.\\nYear: 2018\\n\\nAbstract: Various types and huge number of devices like sensors and actuators are interconnected with clouds of servers in IoT (Internet of Things). Here, a large volume of data including multimedia data like image created by sensors are transmitted to servers in clouds through networks. Processes in servers decide on actions and send the actions to actuators under time constraints like realtime one. However, huge volume of data are transmitted in networks and servers are heavily loaded. An intermediate layer named fog layer is introduced between clouds and devices in IoT to overcome the difficulties. Processing to be done and data to be stored in servers are distributed to fog nodes while centralized on servers in clouds in traditional cloud computing systems. In this paper, we newly propose a linear IoT model to deploy processes and data to devices, fog nodes, and servers in IoT so that the total electric energy consumption of nodes can be reduced. We show the total electric energy of the IoT model is smaller than the cloud model in the evaluation.\",\n \"Title: Concept Of User Authentication Method For The Cloud Type Virtual Policy Based Network Management Scheme For The Specific Domain\\nYear: 2018\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations as a third step, concept of user authentication method applied for this scheme is expanded and described.\",\n \"Title: Design And Implementation Of A Hybrid Intelligent System Based On Particle Swarm Optimization, Hill Climbing And Distributed Genetic Algorithm For Node Placement Problem In Wmns: A Comparison Study\\nYear: 2018\\n\\nAbstract: The Wireless Mesh Networks (WMNs) have low cost and high speed wireless Internet connectivity, therefore they are becoming an important networking infrastructure. In our previous work, we implemented a hybrid intelligent system based on Particle Swarm Optimization (PSO) and Hill Climbing (HC), called WMN-PSOHC, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a new hybrid simulation system based on PSOHC and distributed GA (DGA), called WMN-PSOHC-DGA. We evaluate WMN-PSOHC-DGA system by computer simulations. The simulation results show that the WMN-PSOHC-DGA system has a better performance compared with WMN-PSODGA.\",\n \"Title: Performance Evaluation Of Wmn-Psodga System For Node Placement Problem In Wmns Considering Four Different Crossover Methods\\nYear: 2018\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We evaluate WMN-PSODGA system by computer simulations. The simulation results show that the WMN-PSODGA system has a good performance for SPX crossover method compared with other crossover methods.\",\n \"Title: A Protocol to Prevent Malicious Information Flow in P2PPS Systems\\nYear: 2018\\n\\nAbstract: In the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer process (peer) can publish and subscribe event messages which are characterized by topics with no centralized coordinator. A peer pj publishes an event message ej after receiving an event message ei, i.e. ei causally precedes ej. Here, the event message ej may carry information of the event message ei. If a peer pk receiving ej is not allowed to subscribe the topics of ei, the peer pk illegally obtains the information by receiving ej. In our previous studies, the SBS, TBS, and FS-H protocols are proposed to prevent illegal information flow. In addition, if a source peer pi publishes an event message e without giving related topics or with giving unrelated topics, a destination peer pj may misunderstand the meaning of the event message e. Here, malicious information flow occurs. In this paper, we newly propose a TBSM (topic-based synchronization to prevent malicious information flow) protocol. Here, event messages which may cause malicious information flow are banned. In the evaluation, we show the number of event messages banned in the TBSM protocol is larger than the TBS protocol since the number of event messages which are just malicious is larger than just illegal.\",\n \"Title: Simple Models of Processes Migration with Virtual Machines in a Cluster of Servers\\nYear: 2018\\n\\nAbstract: It is critical to reduce the electric energy consumption of servers in a cluster. In this paper, we discuss a migration approach to reducing the electric energy consumption of servers where a virtual machine with application processes migrates to a more energy-efficient server. In this paper, we consider a homogeneous cluster. We newly propose an ISEAM2H algorithm. Here, a virtual machine on a host server is selected to perform a process issued by an application and a guest server to which a virtual machine migrates is found so that the total electric energy consumption of servers can be minimized. In the evaluation, we show the total electric energy consumption and active time of the servers and the average execution time of processes can be reduced in the ISEAM2H algorithm.\",\n \"Title: Cognitive Systems For Service Management In Cloud Computing\\nYear: 2018\\n\\nAbstract: This paper presents topic of cognitive systems dedicated to management processes. In this paper will be described the cryptographic techniques dedicated to sharing processes with cognitive interpretation stages. Also, safety analysis of these methods will be described. Such algorithms will be presented especially in Cloud Computing context. This solution allow protecting confidential information, and performing secure operation for different kinds of information.\",\n \"Title: An Eco Migration Algorithm of Virtual Machines in a Server Cluster\\nYear: 2018\\n\\nAbstract: Processes on virtual machines can migrate from a host server to a guest server by migrating the virtual machines. In this paper, we propose a DMMV (Dynamic Migration of Multiple Virtual machines) algorithm where virtual machines migrate from a host server to a more energy-efficient guest server. Here, virtual machines are dynamically suspended and resumed depending on the number of processes. In addition, one or more than one virtual machine is selected to migrate from a host server to a guest server. The number of virtual machines to migrate is decided so as to minimize the electric energy consumption of the host and guest servers. In the evaluation, we show not only the total electric energy consumption and active time of servers but also the average execution time of processes can be reduced in the DMMV algorithm compared with other algorithms.\",\n \"Title: An Energy-Efficient Process Replication Algorithm Based on the Active Time of Cores\\nYear: 2018\\n\\nAbstract: Server cluster systems equipped with virtual machines are widely used to realize fault-tolerant systems. Application processes are redundantly performed on multiple virtual machines to realize reliable distributed applications. However, a large amount of electric energy is consumed in a server cluster system since multiple replicas of each application process are redundantly performed on multiple virtual machines. In this paper, the redundant active time-based (RATB) algorithm is proposed to select multiple virtual machines for each application process so that the total electric energy of a server cluster to redundantly perform each application process can be reduced. In the RATB algorithm, it is not necessary for a load balancer to communicate with every virtual machine to estimate the electric energy of each server. Hence, the overhead of a load balancer to estimate the electric energy of each server and forward request processes can be reduced. We evaluate the RATB algorithm in terms of the total electric energy of a server cluster and the average response time of each process compared with the redundant energy consumption laxity based (RECLB) algorithm.\",\n \"Title: Concept of Policy Information Decision Method in the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain\\nYear: 2018\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, the concept of policy information decision method applied for this scheme are described.\",\n \"Title: A flexible read-write abortion protocol with role safety concept to prevent illegal information flow.\\nYear: 2018\\n\\nAbstract: In information systems, illegal information flow among objects has to be prevented. A transaction illegally reads data in an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the FRWA-R (flexible read-write-abortion with role sensitivity) and FRWA-O (object sensitivity) protocols are proposed to prevent illegal information flow. Here, a transaction aborts with some probability once illegally reading data in an object. The abortion probability depends on the sensitivity of roles which the transaction holds and objects in which the transaction illegally reads data. The role sensitivity and object sensitivity show how many transactions which hold the role and illegally read data in the object abort after illegally reading data in the object, respectively. Here, the sensitivity just monotonically increases each time a transaction aborts. In this paper, we propose a new safety concept of a role and an FRWA-RS (FRWA with role safety) protocol. Here, the safety of a role increases and decreases each time a transaction holding the role commits and aborts by issuing an illegal read operation, respectively. A transaction with safer roles aborts with smaller probability. In the evaluation, we show fewer and more numbers of transactions abort in the FRWA-RS protocol than the RWA protocol and than the WA protocol, respectively, and transactions are more efficiently performed than the WA protocol.\",\n \"Title: Dynamic Migration Of Virtual Machines To Reduce Energy Consumption In A Cluster\\nYear: 2018\\n\\nAbstract: Virtual machines are widely used to support applications with virtual service in server clusters. Here, a virtual machine can migrate from a host server to a guest server. In this paper, we consider a cluster where virtual machines are dynamically created and dropped depending on the number of processes. We propose a dynamic virtual machine migration (DVMM) algorithm to reduce the total electric energy consumption of servers. If an application issues a process to a cluster, the most energy-efficient host server is first selected and then the process is performed on a virtual machine of the server. Then, a virtual machine migrates from a host server to a guest server so that total electric energy consumption of servers can be reduced. In the evaluation, we show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the DVMM algorithm.\",\n \"Title: The Improved Transmission Energy Consumption Laxity Based (ITECLB) Algorithm for Virtual Machine Environments.\\nYear: 2018\\n\\nAbstract: Various types of distributed applications are realized in server cluster systems equipped with virtual machines like cloud computing systems. On the other hand, a server cluster system consumes a large amount of electric energy since a server cluster system is composed of large number of servers and each server consumes the large electric energy to perform application processes on multiple virtual machines. In this paper, the improved transmission energy consumption laxity based (ITECLB) algorithm is proposed to allocate communication processes to virtual machines in a server cluster so that the total electric energy consumption of a server cluster and the average transmission time of each communication process can be reduced. We evaluate the ITECLB algorithm in terms of the total electric energy consumption of a server cluster and the average transmission time of each process compared with the transmission energy consumption laxity based (TECLB) algorithm.\",\n \"Title: A Hybrid Simulation System Based on Particle Swarm Optimization and Distributed Genetic Algorithm for WMNs - Performance Evaluation Considering Normal and Uniform Distribution of Mesh Clients.\\nYear: 2018\\n\\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We analyze the performance of WMNs using WMN-PSODGA simulation system considering Normal and Uniform client distributions. Simulation results show that the WMN-PSODGA has good performance for Normal distribution compared with the case of Uniform distribution.\",\n \"Title: An Energy-Efficient Dynamic Live Migration of Multiple Virtual Machines.\\nYear: 2018\\n\\nAbstract: In this paper, we propose an algorithm to migrate virtual machines to reduce the total electric energy consumption of servers. Here, virtual machines are dynamically resumed and suspended so that the number of processes on each virtual machine can be kept fewer. In addition, multiple virtual machines migrate from a host server to a more energy-efficient guest server. In our previous studies, time to migrate virtual machines is assumed to be zero. The more often a virtual machine migrates, the longer time it takes to perform processes on the virtual machine. We propose a model to estimate the electric energy consumption of servers by considering the migration time of each virtual machine. By using the model, virtual machines to migrate and to perform processes are selected so that the total electric energy consumption can be reduced. In the evaluation, we show the total electric energy consumption of servers can be reduced compared with other algorithms.\",\n \"Title: Object-Based Information Flow Control Model in P2PPS Systems.\\nYear: 2018\\n\\nAbstract: In the P2PPS (P2P (peer-to-peer) type of topic-based PS (publish/subscribe)) model, each peer process (peer) publishes and subscribes event messages which are characterized by topics with no centralized coordinator. An illegal information flow occurs if an event message e(j) published by a peer p(j) carries information on some topics into the peer p(i), which the target peer p(i) is not allowed to subscribe. In our previous studies, the SBS, TBS, and FS-H protocols are proposed to prevent illegal information flow among peers by banning event messages. In the protocols, the number of topics kept in every peer monotonically increases. Hence, most of the event messages are banned. In this paper, we newly consider the P2PPSO (P2PPS with object concept) model where the number of topics kept in every peer increases and decreases each time objects obtained by every peer are updated. In order to prevent illegal information flow from occurring in the P2PPSO system, we newly propose a TOBS (topics of objects-based synchronization) and TSOBS (topics and states of objects-based synchronization) protocols. In the TOBS protocol, it is simpler to detect illegal information flow than the TSOBS protocol. On the other hand, the fewer number of event messages are banned in the TSOBS protocol than the TOBS protocol.\",\n \"Title: Consideration of Policy Information Decision Processes in the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\\nYear: 2018\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, the policy information decision processes applied for this scheme are considered and described.\",\n \"Title: Innovative Protocols for Data Sharing and Cyber Systems Security.\\nYear: 2018\\n\\nAbstract: In this paper will be presented new classes of cryptographic secret sharing procedures dedicated for secure information division and transmission. In particular will be presented two classes of protocols, which allow to share information with application of grammar solutions, as well as personal or behavioral parameters. Some possible application of such technologies will also be presented especially with relation to secure data or services management in distributed structures or Cloud environment.\",\n \"Title: Evaluation of an Energy-Efficient Tree-Based Model of Fog Computing.\\nYear: 2018\\n\\nAbstract: A huge number of devices like sensors are interconnected in the IoT (Internet of Things). In the cloud computing model, processes and data are centralized in a cloud. Here, networks are congested and servers are overloaded due to heavy traffic from sensors. In order to reduce the delay time and increase the performance, data and processes to handle the data are distributed to not only servers but also fog nodes in fog computing models. On the other hand, the total electric energy consumed by fog nodes increases to process a sensor data. In this paper, we newly propose a tree-based fog computing model to distribute processes and data to servers and fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the tree-based model is smaller than the cloud computing model.\",\n \"Title: A Causally Precedent Relation Among Messages in Topic-Based Publish/Subscribe Systems.\\nYear: 2018\\n\\nAbstract: Event-driven publish/subscribe (PS) systems are widely used in various types of applications. In this paper, we consider a peer-to-peer (P2P) model of a topic-based PS system which is composed of peer processes (peers) with no centralized coordinator. Here, each peer publishes a message with publication topics while receiving messages whose publication topics are in the subscription topics of the peer. Each peer has to deliver every pair of messages related with respect to topics in the causal order of publication events. In this paper, a message is considered to carry objects whose meanings are denoted by topics. Based on the meanings of objects, we define an object-based-causally (OBC) precedent relation among messages. Based on the OBC precedent relation, we newly propose a protocol to topic-based-causally (TBC) deliver messages to peers. Here, each peer causally delivers event messages which are related with respect to topics. If a message m(1) OBC-precedes a message m2, the message m1 TBC-precedes m(2).\",\n \"Title: Performance Evaluation of Energy Consumption for Different DTN Routing Protocols.\\nYear: 2018\\n\\nAbstract: In this paper, we evaluate the energy consumption of different routing protocols in a Delay Tolerant Network (DTN). Seven groups with three stationary sensor nodes for each group sense the temperature, humidity and wind speed and send these data to a stationary destination node that collects them for statistical and data analysis purposes. The opportunistic contacts will exchange the sensed data to different relay nodes that are pedestrians and cyclist equipped with smart devices moving in Tirana city roads, until the destination node is reached. For simulations we use the Opportunistic Network Environment (ONE) simulator. Nodes in this DTN are energy constrained and play an important role in the success of delivering messages. When the energy of a node is low chance to deliver messages across the network. In this work, we evaluate and compare the performance of different routing protocols in order to find the energy-efficient routing protocol to be used for message transmission for our DTN application. We evaluate the nodes average remaining energy, the number of dead nodes, delivery probability and overhead ratio for different routing protocols.\",\n \"Title: Performance Evaluation of WMNs by WMN-PSOSA Simulation System Considering Constriction and Linearly Decreasing Vmax Methods.\\nYear: 2017\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as low cost and increased high speed wireless Internet connectivity, therefore WMNs are becoming an important networking infrastructure. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on Simulated Annealing (SA) for solving node placement problem inWMNs, calledWMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, calledWMN-PSOSA. We evaluate the performace of WMN-PSOSA by conducting computer simulations considering Constriction Method (CM) and Linearly Decreasing Vmax Method (LDVM). The simulation results show that the LDVM has better performace than CM for this scenario.\",\n \"Title: Routing in a DTN: Performance Evaluation for Random Waypoint and Steady State Random Waypoint Using NS3 Simulator.\\nYear: 2017\\n\\nAbstract: In this paper we evaluate the performance of Epidemic, Spray and Wait and their versions with congestion control and Epidemic with TCP for Random Waypoint (RWP) and Steady State Random Waypoint (SSRWP) mobility models. For performance evaluation, we used delivery ratio, hop count, average delay and average buffer occupancy metrics. Simulations are conducted using NS3 simulator. The simulation results show that the network performance is better for SSRWP mobility model.\",\n \"Title: A Dynamic Model For Energy-Efficiently Migrating A Group Of Virtual Machines From A Host Server To A Guest Server\\nYear: 2018\\n\\nAbstract: In this paper, we newly propose a dynamic migration of a group of v virtual machines [DMG(v)] algorithm to reduce the total electric energy consumption of servers in a cluster. Here, virtual machines are dynamically resumed and suspended so that the number of processes on each virtual machine can be kept fewer. In addition, a group of v (v >= 1) virtual machines migrate from a host server to a guest server so that the total electric energy consumed by the servers can be reduced. In our previous studies, time to migrate each virtual machine is assumed to be zero. In reality, there is migration time every process is suspended on a virtual machine migrating even in the live manner. Hence, the more often a virtual machine migrates, the longer time it takes to perform processes on the virtual machine. We propose a model to estimate electric energy to be consumed by servers through considering the migration time of each virtual machine. By using the estimation model, we can decide on which virtual machines on a host server to which guest server so that the total electric energy consumption of the host and guest servers can be reduced. In the evaluation, we show the total electric energy consumption of servers can be reduced by the DMG(v) algorithm compared with other algorithms.\",\n \"Title: Model of Mobile Objects\\nYear: 1996\\n\\nAbstract: Abstract. Distributed systems are composed of multiple objects. Ob-jects support abstract operations and are distributed in not only xed stations but also mobile ones. While the object is moving from one lo-cation to others, the quality of service (QoS) supported by the object is changed. We model the movement of the object as changes of QoS sup-ported by the object. W e discuss how to support users with QoS required while QoS of the object is being changed. W e present the migration and replication methods as a general framework to treat the disconnected operations. In addition, we present an optimistic concurrency control to maintain the mutual consistency among the replicas.\",\n \"Title: Concurrent Execution of Prolog Transaction\\nYear: 1987\\n\\nAbstract: Information systems are composed of multiple heterogeneous database systems and workstations interconnected by communication networks. Users want to manipulate data in multiple database systems in a common form. In our system, database systems are viewed to be fact base systems (FBSs), which provide sets of Prolog ground unit clauses, and retrieval and update operations on them. Transactions composed of multiple update operations on facts are written as Prolog rule clauses. In the Prolog system, atoms in a goal clause are selected from left to right. This means read/write operations on facts are sequentially executed. In this paper, we try to execute the transaction in parallel by multiple FBSs. In the sequence of atoms in the Prolog transaction, we define two types of meaningful sequences, i.e. conflict and flow ones. In this paper, we present how to decompose transactions into subtransactions, each of which is locally executed by one FBS, so as to preserve the meaningful sequences in the transaction. Also, we show that any parallel execution of the subtransactions is free of deadlock on send-receive relations.\",\n \"Title: Comparison Analysis by WMN-GA Simulation System for Different WMN Architectures, Distributions and Routing Protocols Considering TCP.\\nYear: 2016\\n\\nAbstract: In this paper, we evaluate the performance of two WMN architectures considering Packet Delivery Ratio (PDR), throughput, delay and energy metrics. For simulations, we used ns-3 and Transmission Control Protocol (TCP). We compare the performance for Hybrid Wireless Mesh Protocol (HWMP) and Optimized Link State Routing (OLSR) for normal and uniform distributions of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that the PDR for both distributions and architectures is almost the same, but the PDR of HWMP is a little bit better than OLSR. the throughput is better for normal distribution and I/B WMN architecture in case of HWMP. However, for OLSR and normal distribution, the throughput of Hybrid WMN is a little bit higher than I/B WMN. For both distributions the delay of both architectures is better for HWMP compared with OLSR. For both WMN architectures and routing protocols for normal and uniform distributions, respectively. For normal distribution, the energy decreases sharply, because of the high density of nodes, thus the nodes spend more energy. So, the uniform distribution has better performance compared with normal distribution considering the energy parameter.\",\n \"Title: An Energy-Efficient Process Replication Algorithm in Virtual Machine Environments.\\nYear: 2016\\n\\nAbstract: Server cluster systems are widely used to realize fault-tolerant, scalable, and high performance application services with virtual machine technologies. In order to provide reliable application services, multiple replicas of each application process can be redundantly performed on multiple virtual machines. On the other hand, a server cluster system consumes a large amount of electric energy since multiple replicas of each application process are performed on multiple virtual machines. It is critical to discuss how to realize not only reliable but also energy-efficient server cluster systems. In this paper, we propose the redundant energy consumption laxity based (RECLB) algorithm to select multiple virtual machines for redundantly performing each application process in presence of server faults so that the total energy consumption of a server cluster and the average computation time of each process can be reduced. We evaluate the RECLB algorithm in terms of the total energy consumption of a server cluster and the average computation time of each process compared with the basic round-robin (RR) algorithm.\",\n \"Title: A Probabilistic Encounter and Distance-based Routing Protocol for Opportunistic Networks.\\nYear: 2016\\n\\nAbstract: An Opportunistic Network (OppNet) is one of the latest domain of wireless communication where information is transferred from the source to the destination without any infrastructure, internet connectivity and any predefined network topology. The mobile nodes participating in the network contribute in establishing a connectivity between the nodes to transmit the information from the source to the destination using a store-carry and forward mechanism. The nodes store the information in their in-built buffer until a suitable forwarder is available within their wi-fi/bluetooth transmission range. Designing a routing protocol in OppNet is thus a challenging task. This paper proposes a Probabilistic Encounter and Distance-based Routing Protocol (P-EDR) for Opportunistic Networks, which is designed as a combination the ProPHet and the Encounter and Distance-based Routing (EDR) protocols. Simulation results are presented, showing that P-EDR outperforms the EDR, History-based Prediction for Routing (HBPR) and ProPHet routing protocols in terms of message delivery probability, messages overhead ratio and number of messages dropped.\",\n \"Title: An energy-aware load balancing algorithm to perform computation type application processes in a cluster of servers.\\nYear: 2017\\n\\nAbstract: A cluster of servers is getting scalable and widely used in various types of applications. It is critical to reduce the electric energy consumed by servers in a cluster to realise eco society. In this paper, we newly propose an improved delay time based IDTB algorithm to reduce the total electric energy consumption of a cluster and to more efficiently utilise the computation resources for performing application processes in a cluster. In the IDTB algorithm, a load balancer estimates the state of each server just by using responses from processes and without additionally communicating with servers to collect states of the servers. We evaluate the IDTB algorithm compared with the basic round-robin RR, improved power consumption laxity based IPCLB, and delay time based DTB algorithms. We show the total electric energy consumption of a cluster and response time of each process can be reduced in the IDTB algorithm.\",\n \"Title: Hybrid Replication Schemes of Processes in Energy-Efficient Server Clusters.\\nYear: 2017\\n\\nAbstract: In order to fault-tolerantly perform an application process in a server cluster, the process is replicated on multiple servers. Even if some replicas of the process is faulty, e.g. due to stop-fault of the host server, the process can be successfully performed as long as some number of replicas are operational. The more number of replicas of a process are performed, the more reliably and availably the process can be performed but the more electric energy is consumed. In this paper, we make clear what software components each replica of a process includes. We newly propose new replication schemes which are composed of a primary replica and more types of secondary replicas so that the total electric energy consumption can be reduced while the reliability and availability of each process can be increased. In the evaluation, we show the electric energy consumption of servers can be reduced in the replication schemes compared with the traditional active and passive replication schemes.\",\n \"Title: Implementation of an intelligent hybrid simulation systems for WMNs based on particle swarm optimization and simulated annealing: performance evaluation for different replacement methods\\nYear: 2019\\n\\nAbstract: Wireless mesh networks (WMNs) have many advantages such as low-cost and increased high- speed wireless Internet connectivity; therefore, WMNs are becoming an important networking infrastructure. In our previous work, we implemented a particle swarm optimization (PSO)-based simulation system for node placement in WMNs, called WMN-PSO. Also, we implemented a simulation system based on simulated annealing (SA) called WMN-SA. In this paper, we implement a hybrid simulation system based on PSO and SA, called WMN-PSOSA. We evaluate the performance of WMN-PSOSA by conducting computer simulations considering four different replacement methods. The simulation results show that the rational decrement of Vmax method and linearly decreasing inertia weight method have better performance compared with constriction method and random inertia weight method.\",\n \"Title: An Information Flow Control Model In A Topic-Based Publish/Subscribe System\\nYear: 2018\\n\\nAbstract: A publish/subscribe (PS) model is an event-driven model of a distributed system. In traditional PS systems, each peer (process) can either publish or subscribe events. In this paper, we consider a peer-to-peer (P2P) type of topic-based PS model where each peer can both publish and subscribe events. In this paper, we newly propose a topic-based access control (TBAC) model for topic-based PS systems. Here, an access right is a pair < t, op > of a topic t and a publish or subscribe operation op. A peer is allowed to publish an event message with publication topics and subscribe interesting topics only if the publication and subscription access rights are granted to the peer, respectively. An event message e is delivered to a peer p(i) if the publication of e and subscription of pi include some common topic. If a peer pi publishes an event message e2 after receiving an event message e1, the event message e2 may bring some information of the event message e1. If a target peer p(j) is not allowed to subscribe at least one topic which is related with the event message e1, information in the peer pi illegally flows to the target peer pj. We newly propose a subscription-based synchronization (SBS) protocol to prevent illegal information flow. Here, an event message is banned by a target peer if the event message implies illegal information flow. However, event messages may be unnecessarily banned by a peer even if no illegal information flow to the peer occurs. In the evaluation, we show the number of event messages unnecessarily banned in the SBS protocol.\",\n \"Title: Simple Algorithms For Selecting An Energy-Efficient Server In A Cluster Of Servers\\nYear: 2018\\n\\nAbstract: Electric energy consumed by computers, especially servers in scalable clusters has to be reduced to realise eco society. In this paper, we first propose a multi-level power consumption (MLPCM) model which gives how much electric power a server consumes to perform application processes. We also propose an multi-level computation (MLCM) model which shows the expected execution time of an application process performed on a server. By using the MLPCM and MLCM models, we propose a pair of simple locally energy-aware (SLEA) and simple globally energy-aware (SGEA) algorithms to select a host server to perform an application process issued by a client. In the SLEA algorithm, a host server is selected, which is expected to consume the minimum electric energy to perform the process. In the SGEA algorithm, a host server is selected, where the total expected electric energy consumption of not only the host server but also the other servers is minimum. In the evaluation, we show the total electric energy consumption and active time of servers and the average execution time of processes can be reduced in the SGEA algorithm compared with other algorithms.\",\n \"Title: Energy consumption laxity-based quorum selection for distributed object-based systems\\nYear: 2020\\n\\nAbstract: In object based systems, an object is an unit of computation resource. Distributed applications are composed of multiple objects. Objects in an application are replicated to multiple servers in order to increase reliability, availability, and performance. On the other hand, the large amount of electric energy is consumed in a system compared with non-replication systems since multiple replicas of each object are manipulated on multiple servers. In this paper, the energy consumption laxity-based quorum selection (ECLBQS) algorithm is proposed to construct a quorum for each method issued by a transaction so that the total electric energy consumption of servers to perform methods can be reduced in the quorum based locking protocol. The total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted transactions are shown to be more reduced in the ECLBQS algorithm than the random algorithm in evaluation.\",\n \"Title: Evaluation of a Protocol to Prevent Malicious Information Flow in P2PPS Systems.\\nYear: 2018\\n\\nAbstract: In the peer-to-peer (P2P) type of topic-based publish/subscribe (P2PPS) model, each peer process (peer) can publish and subscribe event messages which are characterized by topics with no centralized coordinator. A peer p(j) publishes an event message e(j) after receiving an event message e(i), i.e. ei causally precedes ej. Here, the event message e(j) may carry information of the event message e(i). If a peer pk receives ej but is not allowed to subscribe the topics of e(i), the peer p(k) illegally obtains the information of e(i) via e(j). In addition, if a source peer pi publishes an event message e without related topics or with unrelated topics, a destination peer p(j) may misunderstand the meanings of the event message e, i.e. the event message e is maliciously received by the peer p(j). In our previous studies, the SBS, TBS, FS-H protocols and the TBSM protocol are proposed to ban illegal and malicious event messages, respectively. In this paper, we evaluate the TBSM protocol in terms of the numbers of illegal and malicious types of event messages. In the evaluation, we show the ratio of the number of event messages banned decreases as the numbers of topics in a system increases.\",\n \"Title: An energy-efficient model for fog computing in the Internet of Things (IoT)\\nYear: 2018\\n\\nAbstract: A huge number of devices like sensors in addition to computers are interconnected in the IoT (Internet of Things). In the cloud computing model, sensor data is transmitted to servers in networks and processed on the servers in a cloud. Here, networks are congested and servers are overloaded due to heavy traffic from sensors. In order to reduce the delay time and network traffic and increase the performance of the system, data and processes are distributed to not only servers in a cloud but also fog nodes in fog computing models. While the traffic of servers in a cloud can be reduced, the total electric energy consumed by fog nodes increases to process sensor data. In this paper, we newly propose a tree-based fog computing (TBFC) model to distribute processes and data to servers and fog nodes so that the total electric energy consumption of nodes can be reduced in the IoT. In the evaluation, we show the total electric energy consumption of nodes in the TBFC model is smaller than the cloud computing model.\",\n \"Title: A Virtual Machine Migration for Storage Processes\\nYear: 2018\\n\\nAbstract: Virtual machines are widely used to support applications with virtual computation service of computer resources like CPUs and storages in a cluster of servers. Application processes on a virtual machine can take usage of not only CPUs but also storage resources like files and databases independently of heterogeneity and location of each host server. In addition, virtual machines can migrate from a host server to a guest server in the live manner. In this paper, we consider storage processes which read and write data in files of storages like HDD. Through experiments, we make clear the execution time of a storage process on a virtual machine while the virtual machine is migrating among servers. We propose a model for using virtual machines where storage processes are performed and migrate from host servers to guest servers.\",\n \"Title: Object-Based Selective Delivery of Event Messages in Topic-Based Publish/Subscribe Systems\\nYear: 2018\\n\\nAbstract: A peer-to-peer (P2P) model of a topic-based publish/subscribe system is composed of peer processes (peers) with no centralized coordinator. Each peer publishes a message with publication topics while receiving messages whose publications include subscription topics. Each peer has to causally deliver every pair of messages related in terms of topics. Based on objects carried by messages, we define on object-based-causally (OBC) and topic-based-causally (TBC) precedent relations among the messages. We newly propose a protocol to TBC-deliver messages to peers. If a message m(1) OBC-precedes a message m(2), m(1) TBC-precedes m(2). On the other hand, even if m(1) TBC-precedes m(2), m(1) may not OBC-precede m(2).\",\n \"Title: Consideration of Implementation Method for the Cloud Type Virtual Policy Based Network Management Scheme for the Specific Domain.\\nYear: 2019\\n\\nAbstract: In the current Internet system, there are many problems using anonymity of the network communication such as personal information leaks and crimes using the Internet system. This is why TCP/IP protocol used in Internet system does not have the user identification information on the communication data, and it is difficult to supervise the user performing the above acts immediately. As a study for solving the above problem, there is the study of Policy Based Network Management (PBNM). This is the scheme for managing a whole Local Area Network (LAN) through communication control for every user. In this PBNM, two types of schemes exist. As one scheme, we have studied theoretically about the Destination Addressing Control System (DACS) Scheme with affinity with existing internet. By applying this DACS Scheme to Internet system management, we will realize the policy-based Internet system management. In this paper, to realize management of the specific domain with some network groups with plural organizations, concept of implementation method applied for this scheme is described.\",\n \"Title: Energy-Efficient Group Migration of Virtual Machines in a Cluster.\\nYear: 2019\\n\\nAbstract: In order to realize green society, we take the process migration approach to reducing the total electric energy consumption of clusters by migrating virtual machines. In our previous studies, the DM (Dynamic Migration) algorithm is proposed where virtual machines are dynamically resumed and suspended and a group of virtual machines on a host server migrate to a guest server so that the total energy consumption of the host and guest servers can be reduced. In this paper, we newly propose a DGM (Dynamic Group Migration) algorithm. Here, there is a seed virtual machine on each server. A virtual machine is created as a clone of the seed virtual machine so that the number of processes on each virtual machine is kept fewer. In the evaluation, we show the total electric energy consumption of servers can be more reduced in the DGM algorithm compared with other algorithms.\",\n \"Title: Selection of IoT Devices in Opportunistic Networks - A Fuzzy-Based Approach Considering IoT Device's Selfish Behaviour.\\nYear: 2019\\n\\nAbstract: In opportunistic networks the communication opportunities (contacts) are intermittent and there is no need to establish an end-to-end link between the communication nodes. The enormous growth of devices having access to the Internet, along the vast evolution of the Internet and the connectivity of objects and devices, has evolved as Internet of Things (IoT). There are different issues for these networks. One of them is the selection of IoT devices in order to carry out a task in opportunistic networks. In this work, we implement a Fuzzy-Based System for IoT device selection in opportunistic networks. For our system, we use four input parameters: IoT Device’s Selfish Behaviour (IDSB), IoT Device Remaining Energy (IDRE), IoT Device Storage (IDST) and IoT Device Contact Duration (IDCD). The output parameter is IoT Device Selection Decision (IDSD). The simulation results show that the proposed system makes a proper selection decision of IoT devices in opportunistic networks. The IoT device selection is increased up to 14% and decreased 23% by increasing IDRE and IDSB, respectively.\",\n \"Title: Performance Analysis of WMNs by WMN-PSODGA Simulation System Considering Weibull and Chi-square Client Distributions.\\nYear: 2019\\n\\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. Then, we implemented a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. In this paper, we analyze the performance of WMNs using WMN-PSODGA simulation system considering Weibull and Chi-square client distributions. Simulation results show that a good performance is achieved for Chi-square distribution compared with the case of Weibull distribution.\",\n \"Title: A Fuzzy-Based System for Actor Node Selection in WSANs Considering Level of Received Signal.\\nYear: 2019\\n\\nAbstract: Wireless Sensor and Actor Network (WSAN) is formed by the collaboration of micro-sensor and actor nodes. The sensor nodes have responsibility to sense an event and send information towards an actor node. The actor node is responsible to take prompt decision and react accordingly. In order to provide effective sensing and acting, a distributed local coordination mechanism is necessary among sensors and actors. In this work, we consider the actor node selection problem and propose a fuzzy-based system (FBS) that based on data provided by sensors and actors selects an appropriate actor node. We use 4 input parameters: Distance to Event (DE), Number of Sensors per Actor (NSA), Remaining Energy (RE) and Level of Received Signal (LRS) as new parameter. The output parameter is Actor Selection Decision (ASD). Considering NSA parameter, the ASD has better values when NSA is medium. Thus, when the NSA value is 0.5 the load is distributed better and in this situation the possibility for the actor to be selected is high. Also, for higher values of LRS, the actor is selected with high possibility.\",\n \"Title: The Improved Energy-Efficient Quorum Selection with Excluding Meaningless Methods.\\nYear: 2019\\n\\nAbstract: In distributed object-based systems, applications manipulate objects distributed on multiple servers. In order to provide reliable and available application services, each object is replicated on multiple servers and replicas of each object have to be mutually consistent. On the other hand, since methods issued to each object are performed on multiple replicas, the total amount of electric energy consumed in a system increases. In our previous studies, the IEEQS (improved energy efficient quorum selection) algorithm is proposed to reduce the total electric energy of servers by omitting only meaningless write methods. In this paper, the IEEQS-EMM (IEEQS with excluding meaningless methods) algorithm is proposed to furthermore reduce the total electric energy of servers by omitting meaningless read and write methods. Evaluation results show the total electric energy of servers can be reduced in the IEEQS-EMM algorithm than the IEEQS algorithm.\",\n \"Title: Efficient Information Flow Control by Reducing Meaningless Messages in P2PPSO Systems.\\nYear: 2019\\n\\nAbstract: In topic-based publish/subscribe (PS) model, each peer process (peer) only receives an event message whose publication topics include some common topic with the subscription topics. In a P2PPSO (P2P (peer-to-peer) type of topic-based PS with Object concept) model, each peer exchanges objects by publishing and receiving event messages with no centralized coordinator. Here, objects are denoted by topics and event messages are characterized by topics of the objects carried by the event messages. Suppose an event message (e_j) published by a peer (p_j) carries objects on some topics into a target peer (p_i). Here, objects in the peer (p_j) illegally flow to the peer (p_i) if the peer (p_i) is not allowed to subscribe the topics. An object of a peer (p_i) is illegal, whose topics the peer (p_i) is not allowed to subscribe. In this paper, we newly propose an ETOBSCO (Efficient TOBSCO) protocol where meaningless event messages are not published to reduce the number of event messages exchanged among peers. In the evaluation, we show the fewer number of event messages are delivered but longer update delay time to update replicas is taken in the ETOBSCO protocol.\",\n \"Title: Biometric-Based Linguistic Solutions for Data Encryption and Sharing.\\nYear: 2019\\n\\nAbstract: This paper will describe new hybrid classes of secret sharing protocols joining features of linguistic secret division procedures with biometric threshold schemes. Such advanced protocols will be defined with application of different classes of formal grammars with standard or non-standard biometric patterns. Evaluation of such method will be done, as well as possible application for data and services management will be presented.\",\n \"Title: Energy-Efficient Recovery Algorithm in the Fault-Tolerant Tree-Based Fog Computing (FTBFC) Model.\\nYear: 2019\\n\\nAbstract: In order to reduce the traffic of networks and servers, the fog computing model is proposed to realize the IoT (Internet of Things). In our previous studies, the fault-tolerant tree-based fog computing (FTBFC) model is proposed to be tolerant of faults of fog nodes. If a fog node (f_{j}) is faulty, child fog nodes of (f_{j}) are disconnected. Another operational fog node (f_{i}) at the same level as (f_{j}) is a candidate parent node of disconnected nodes. One candidate node is selected to be a parent of every disconnected node. However, the new parent node (f_{i}) has to additionally process data from the disconnected nodes. In order to reduce the energy consumption of each new parent node, we propose a modified FTBFC (MFTBFC) model where disconnected nodes are partitioned into groups and fog nodes in each group are connected to a different candidate node. We also propose an SMPR (selecting multiple parents for recovery) algorithm to select a candidate parent node for each disconnected node so that the electric energy consumption of each new parent node can be reduced. In the evaluation, we show the energy consumption and execution time of each new parent fog node can be reduced in the SMPR algorithm.\",\n \"Title: Centrality Based Geocasting for Opportunistic Networks.\\nYear: 2019\\n\\nAbstract: Opportunistic networks (OppNets) are a subclass of delay tolerant networks characterized by unstable topology, intermittent connectivity, and no guarantee of the existence of an end-to-end path to carry the messages from source to destination because of node’s mobility. For these reasons, the routing of data in such networks occurs in a store-carry-and-forward approach. Following this approach combined with geocasting as message transmission strategy, this paper proposes a geo-casting protocol for OppNets named Centrality based Geocasting for OPPortunistic networks (CGOPP for short). The proposed scheme combines uni-casting and flooding by first transferring a message to an individual geographic location, then intelligently flood the message to all nodes inside the area by using a degree centrality function. Simulation results are provided, demonstrating the efficiency of the proposed protocol against traditional geo-casting protocols for OppNets, in terms of average latency, delivery ratio, and number of messages forwarded, under varying number of nodes, buffer sizes, and TTL.\",\n \"Title: Linguistic and Biometric Approaches for Data and Services Management in Cloud Computing\\nYear: 2018\\n\\nAbstract: This paper will describe new classes of secure secret sharing procedures applied for information and services management. In particular will be presented two classes of procedures which allow to share data and services, using personal biometric characteristics and mathematical linguistic approaches. Examples of application of such technologies will also be presented connected with distributed services in Cloud Computing infrastructures.\",\n \"Title: Group Migration of Virtual Machines in a Server Cluster\\nYear: 2018\\n\\nAbstract: In this paper, we propose an algorithm to migrate a group of virtual machines among servers in a cluster so that the total electric energy consumption of the host and guest servers can be reduced. We propose a pair of static SM(v) and dynamic DM(v) algorithms where at most v (>= 0) virtual machines migrate from a host server to a guest server. In the DM(v) algorithm, virtual machines are dynamically resumed and suspended as the number of application processes increases and decreases. In the evaluation, we show the total electric energy consumption of servers can be reduced in the DM(v) algorithm compared with other algorithms.\",\n \"Title: Evaluation of Object-Based Information Flow Control in P2PPS Systems\\nYear: 2018\\n\\nAbstract: In the P2PPSO (P2P (peer-to-peer) type of topic-based PS (publish/subscribe) with object concept) model, each peer process (peer) exchanges objects by publishing and subscribing event messages which are characterized by topics with no centralized coordinator. Information in a peer p(i) illegally flows to a peer p(j) if an event message e(i) published by the peer p(i) carries an object on some topics into the target peer p(j), which is not allowed to subscribe the topics. In our previous studies, a TOBS (topics of objects-based synchronization) protocol is proposed to prevent illegal information flow in the P2PPSO system. In the TOBS protocol, an illegal object whose topics a target peer is not allowed to subscribe is not delivered to the target peer. In this paper, we evaluate the TOBS protocol in terms of the number of event messages including at least one illegal object. In the evaluation, we show the number of event messages including illegal objects in the TOBS protocol.\",\n \"Title: The Improved Transmission Energy Consumption Laxity-Based Algorithm with Parallel Data Transmission\\nYear: 2018\\n\\nAbstract: Various kinds of approaches are proposed to reduce the total electric energy consumption of a server cluster system equipped with virtual machines. In order to design and implement energy-efficient server cluster systems, processing load of virtual machines to perform application processes has to be balanced with one another to not only reduce the total electric energy consumption of a server cluster but also satisfy application's performance requirements like turn-around time for each client. In this paper, the ITECLB-P (improved transmission energy consumption laxity based algorithm with parallel data transmission) algorithm is proposed to allocate communication processes to virtual machines in a server cluster so that the total electric energy consumption of a server cluster and the average turn-around time of each client can be reduced. In the evaluation, we show the total electric energy consumption of a server cluster and the average turn-around time of each client can be reduced in the ITECLB-P algorithm compared with the improved transmission energy consumption laxity based (ITECLB) algorithm.\",\n \"Title: Performance Behavior of WMN-PSODGA Simulation System for WMNs Considering Uniform and Chi-Square Client Distributions\\nYear: 2018\\n\\nAbstract: The Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure because they have many advantages such as low cost and increased high speed wireless Internet connectivity. In our previous work, we implemented a Particle Swarm Optimization (PSO) based simulation system, called WMN-PSO, and a simulation system based on Genetic Algorithm (GA), called WMN-GA, for solving node placement problem in WMNs. In this paper, we implement a hybrid simulation system based on PSO and distributed GA (DGA), called WMN-PSODGA. We analyze the performance of WMNs using WMN-PSODGA simulation system considering Uniform and Chi-square client distributions. Simulation results show that the WMN-PSODGA has good performance for Chi-square distribution compared with the case of Uniform distribution.\",\n \"Title: Information flow control in object-based peer-to-peer publish/subscribe systems: Information flow control in object-based peer-to-peer publish/subscribe systems\\nYear: 2020\\n\\nAbstract: In this paper, we propose a P2PPSO (P2P [peer-to-peer] type of topic-based Publish/Subscribe with Object concept) model, where each peer process (peer) exchanges objects by publishing and receiving event messages with no centralized coordinator. In addition, objects are characterized by topics. Suppose an event message e(j) published by a peer p(j) carries an object on some topics into a target peer p(i). Here, information in the peer p(j) illegally flows to the peer p(i) if the target peer p(i) is not allowed to subscribe the topics. An illegal object is an object whose topics a target peer is not allowed to subscribe. Even if an event message is received by a target peer by checking topics, objects carried by the event message may be illegal at the target peer. In this paper, we propose a TOBS (topics-of-objects-based synchronization) protocol to prevent target peers from receiving illegal objects in the P2PPSO model. Here, even if an event message is received by a target peer, illegal objects in the event message are not delivered to the target peer. In the evaluation, we show how many event messages carry illegal objects in the TOBS protocol.\",\n \"Title: Causally ordering delivery of event messages in P2PPSO systems\\nYear: 2019\\n\\nAbstract: In topic-based PS (Publish/Subscribe) model, each peer process (peer) specifies subscription topics and publishes an event message with publication topics. A peer only receives an event message whose publication topics include some common topic with the subscription topics. In the P2PPSO (P2P (peer-to-peer) type of topic-based Publish/Subscribe with Object concept) model, each peer exchanges objects by publishing and receiving event messages with no centralized coordinator. Here, objects are denoted by topics and event messages are characterized by topics of the objects in the event messages. Suppose an event message ej published by a peer pj carries objects on some topics into a target peer pi. Information, i.e. objects in the peer pj illegally flows to the peer pi if the peer pi is not allowed to subscribe the topics. An illegal object of a peer pi is an object whose topics the peer pi is not allowed to subscribe. In the TOBS (Topics-of-Objects-Based Synchronization) protocol, illegal objects are not delivered to target peers, but every event message is assumed to be causally delivered in the underlying network. In this paper, we newly propose a TOBSCO (TOBS with Causally Ordering delivery) protocol where the function to causally deliver every pair of event messages is added to the TOBS protocol. In the evaluation, we show every pair of event messages are causally delivered and it takes longer to deliver event messages in the TOBSCO protocol.\",\n \"Title: Evaluation of a Two-Way Tree-Based Fog Computing (TWTBFC) Model.\\nYear: 2019\\n\\nAbstract: In our previous studies, the TBFC (Tree-Based Fog Computing) model is proposed to reduce the electric energy consumed by fog nodes and servers in the fog computing model. Here, fog nodes are hierarchically structured in a height-balanced tree. A root node shows a cloud of servers and leaf nodes are edge nodes which collect data from sensors and send actions to actuators. Each node receives data from child nodes and sends the processed data to a parent node. Finally, servers receive sensor data processed by fog nodes and send actions to actuators. Thus, sensor data is sent up to a root node from sensors and action are sent down to actuators from the root node. In order to more promptly deliver actions to actuators, the TWTBFC (Two-Way TBFC) model is proposed where nodes send processed data not only to a parent node but also to each child node. Thus, each node can get more global data obtained by processing data from every sibling node. The node can make a decision on actions to be done by descendant nodes. On the other hand, more amount of data is transmitted in networks and processed by a fog node. In this paper, we discuss how to reduce the processing load of each node in the TWTBFC model.\",\n \"Title: The Improved Energy Consumption Laxity Based (IECLB) Algorithm to Perform Computation Processes.\\nYear: 2019\\n\\nAbstract: The total electric energy consumption of a server cluster to perform application processes on multiple virtual machines has to be reduced to realize energy-efficient information systems. In our previous studies, the ECLB (energy consumption laxity based) algorithm to allocate computation type application processes (computation processes) to virtual machines in a server cluster is proposed so that the total electric energy consumption of the server cluster can be reduced. Here, each virtual machine is bounded to one thread on a CPU in a server and computation processes are performed by using only one thread bounded to the virtual machine even if some threads are not used in the server. In this paper, the improved ECLB (IECLB) algorithm is proposed to furthermore reduce the total electric energy consumption of a server cluster by allocating unused threads to each virtual machine to perform computation processes. We evaluate the IECLB algorithm in terms of the total electric energy consumption of a server cluster compared with the ECLB algorithm.\",\n \"Title: Capability-Based Information Flow Control Model in the IoT.\\nYear: 2019\\n\\nAbstract: Various types and huge number of nodes including not only computers like servers but also devices like sensors and actuators are interconnected in the IoT (Internet of Things). Here, the CapBAC (Capability-Based Access Control) model is proposed in the IoT system. In the CapBAC model, an owner of a device issues a capability token, i.e. a set of access rights to a subject. Here, the subject is allowed to manipulate the device according to the access rights in the capability token. In the IoT, a subject sb(i) can get the data of the device d(1) from another device d(2) to which the data of the device d(1) is brought although the subject sb(i) is not allowed to get the data from the device d(1). Here, the data in the device d(1) illegal flows to the subject sb(i). In this paper, first, we newly define information flow relations among devices based on the CapBAC model. Next, we newly propose an OI (Operation Interruption) protocol to prevent illegal information flow in the IoT based on the information flow relations among devices. In the OI protocol, an operation to imply illegal information flow is interrupted.\",\n \"Title: A Synchronization Protocol to Prevent Illegal Information Flow Based on Maximal Roles in the Role-Based Access Control Model.\\nYear: 2018\\n\\nAbstract: In access control models, a transaction is allowed to read and write an object only if access rights to read and write the object are granted, respectively. Suppose a transaction T-1 reads data d from a file object f(1) and then writes the data d to another file object f(2). Here, another transaction T-2 can get the data d by reading the file object f(2) even if T-2 is not granted a read right on the file object f(1). Here, information in the file object f(1) flows to the transaction T-2 via the file object f(2). We have to prevent illegal information flow to occur by transactions manipulating objects. The role-based access control (RBAC) model is widely used in various applications like database systems. In our previous studies, the legally precedent relation from a role to a role is defined. However, even if the legal condition is satisfied, there is case illegal information flow occurs. In this paper, we redefine legal and illegal precedent relations among roles. In order to check if a collection A of roles illegally precedes a collection B of roles, we introduce a new condition which uses maximal roles of A and B.\",\n \"Title: A Fuzzy-Based System for Safe Driving Information in VANETs.\\nYear: 2018\\n\\nAbstract: Ambient intelligence (AmI) deals with a new world of ubiquitous computing devices, where physical environments interact intelligently and unobtrusively with people. AmI environments can be diverse, such as homes, offices, meeting rooms, schools, hospitals, control centers, vehicles, tourist attractions, stores, sports facilities, and music devices. In this paper, we propose a Fuzzy-based system for safe driving information in VANETs. The proposed system considers in-car environment data and driver's vital signs data to make the decision. Then uses the smart-box to inform the driver and change his mood. We want to realize a new system to support the driver for save driving. We evaluated the performance of proposed system by computer simulations. From the simulations results, we conclude that the driver vital information, vehicle mobility information and car environment information have different effects to the driver.\",\n \"Title: Performance Comparison Of Cm And Ldvm Router Replacement Methods For Wmns By Wmn-Psosa-Dga Hybrid Simulation System Considering Stadium Distribution Of Mesh Clients\\nYear: 2021\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages such as: easy maintenance, low upfront cost and high robustness. The connectivity and stability affect directly the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we compare the performance of Constriction Method (CM) and Linearly Decreasing Vmax Method (LDVM) for WMNs by using the WMN-PSOSA-DGA hybrid simulation system considering the Stadium distribution of mesh clients. Simulation results show that LDVM has better performance than CM.\",\n \"Title: Transformative Computing Based On Advanced Human Cognitive Processes\\nYear: 2021\\n\\nAbstract: Currently, data analysis processes based on individual, personalized recording techniques are used more and more. Such processes allow for intelligent data analysis considering only those elements that are of significant importance to a specific recipient. In addition, they provide the possibility of applying individual analysis results to deep data analysis processes. In this paper, such possibilities of data analysis will be described, with particular emphasis on the use of transformational computing technology taking into account advanced human cognitive processes.\",\n \"Title: Performance Evaluation of WMNs by WMN-PSOSA-DGA Hybrid Simulation System Considering Stadium Distribution of Mesh Clients and Different Number of Mesh Routers\\nYear: 2021\\n\\nAbstract: Wireless Mesh Networks (WMNs) are gaining a lot of attention from researchers due to their advantages such as easy maintenance, low upfront cost, and high robustness. Connectivity and stability directly affect the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we evaluate the performance of WMNs by using the WMN-PSOSA-DGA hybrid simulation system considering the Stadium distribution of mesh clients. Simulation results show that 32 mesh routers are enough for maximizing the network connectivity and user coverage.\",\n \"Title: The Redundant Active Time-Based Algorithm with Forcing Meaningless Replica to Terminate\\nYear: 2021\\n\\nAbstract: Reliable and available distributed application services can be provided by redundantly performing each application process. However, multiple replicas of each application process are performed on multiple virtual machines in a server cluster system. As a result, a server cluster consumes a large amount of electric energy to provide application services. In this paper, the RATB-FMRT (redundant active time-based with forcing meaningless replicas to terminate) algorithm is proposed to reduce the total electric energy consumption of a server cluster by forcing meaningless replica to terminate. In the evaluation, we show the total electric energy consumption of a server cluster and the average response time of each process can be reduced in the RATB-FMRT algorithm.\",\n \"Title: Information Flow Control Based on Capability Token Validity for Secure IoT: Implementation and Evaluation\\nYear: 2021\\n\\nAbstract: In the CBAC (Capability-Based Access Control) model proposed for realizing the secure IoT (Internet of Things), authorizers issue subjects capability tokens, i.e. sets of access rights on objects in devices. Objects are data resources which are used to store sensor data and action data. Data of an object may be stored in another object through communication among subjects and devices. A subject can get data of an object from another object even if the subject is not allowed to get the data, i.e. information illegally flows from the object to the subject. In addition, a subject can get data generated at time before which the capability token to get the data starts to be valid. Here, information flows from the object to the subject later than expected by the subject to get the data. In our previous studies, the OI (Operation Interruption) and the TBOI (Time-Based OI) protocols are proposed to interrupt operations implying illegal type of information flow and not only illegal but also late types of information flows, respectively. In this paper, the TBOI protocol is designed and implemented. In the evaluation, it is shown the late information flow is prevented in addition to the illegal one in the TBOI protocol although the request processing time is almost the same as the OI protocol.\",\n \"Title: Probability And Topic-Based Data Transmission Protocol\\nYear: 2021\\n\\nAbstract: In the fog computing (FC) models, a fog node supports not only routing functions but also application processes. By the application processes, output data are calculated on input data from sensors and other nodes and sent to target fog nodes which can calculate on the output data. In this article, we consider the mobile topic-based publish/subscribe fog computing (MPSFC) model where mobile fog nodes communicate with one another by publishing and subscribing messages in wireless networks. Subscription topics of a fog node denote input data on which the node can calculate output data. Publication topics of a message show data carried by the message. In the topic-based data transmission (TBDT) protocol proposed in our previous studies, while a fewer number of messages are transmitted, the delivery ratio of messages is smaller than the epidemic routing protocol. In this article, we newly propose a pair of time-to-live-based data transmission (TTLBDT) and probability and topic-based data transmission (PTBDT) protocols in order to increase the delivery ratio. If another node is found in the communication range, a fog node forwards messages to the node. Even if the node is not a target node, the node receives the message with some probability in the PTBDT protocol. In the evaluation, we show the delivery ratios in the TTLBDT and PTBDT protocols are larger than the TBDT protocol. In addition, we show the number of messages exchanged in the PTBDT protocol is smaller than the epidemic routing protocol.\",\n \"Title: Performance Analysis of RIWM and RDVM Router Replacement Methods for WMNs by WMN-PSOSA-DGA Hybrid Simulation System Considering Stadium Distribution of Mesh Clients\\nYear: 2021\\n\\nAbstract: Wireless Mesh Networks (WMNs) have many advantages, for example easy maintenance, low upfront cost and high robustness. However, WMNs have some problems to be solved such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO), Simulated Annealing (SA) and Distributed Genetic Algorithm (DGA), called WMN-PSOSA-DGA. In this paper, we compare the performance of Random Inertia Weight Method (RIWM) and Rational Decrement of Vmax Method (RDVM) for WMNs by using WMN-PSOSA-DGA hybrid simulation system considering Stadium distribution of mesh clients. Simulation results show that RDVM has better performance than RIWM.\",\n \"Title: Modern Cognitive Solutions for Advanced Information Processing\\nYear: 2021\\n\\nAbstract: This paper will discuss modern cognitive solutions dedicated to information processing. Cognitive processes, as the most individual methods of information processing, are characteristic of every human being, and thus transferred to the ground of machine solutions, they offer the possibility of deep, meaningful data analysis. Their distinguishing feature is that they are based on a semantic interpretation based on a linguistic description. The possibility of using such solutions in information processing will allow to show their universality and usefulness.\",\n \"Title: An Energy-Efficient Algorithm to Make Virtual Machines Migrate in a Server Cluster\\nYear: 2021\\n\\nAbstract: Applications can take advantage of virtual computation services independently of heterogeneity and locations of servers by using virtual machines in clusters. Here, a virtual machine on an energy-efficient host server has to be selected to perform an application process. In this paper, we propose an SMI (Simple MI) algorithm to estimate the energy consumption of a server to perform application processes. Then, we propose an SMIM (SMI Migration) algorithm to make a virtual machine migrate from a host server to a guest server to reduce the total energy consumption of the servers by using the SMI algorithm. In the evaluation, we show the energy consumption of servers in a cluster can be reduced in the SMIM algorithm compared with other algorithms.\",\n \"Title: Time-based legality of information flow in the capability-based access control model for the Internet of Things\\nYear: 2021\\n\\nAbstract: The Internet of Things is composed of sensor and actuator devices. Devices have to be securely accessed by subjects. In this article, we take the capability-based access control (CBAC) model where a subject is issued a capability token to manipulate a device by a device owner. In the CBAC model, information which a subject is not allowed to get may illegally flow to the subject. Hence, the operation interruption (OI) protocol to prevent illegal information flow is proposed in our previous studies. However, although a subject is not allowed to get data at time tau, the subject can get the data later than the time tau. Here, the data come to the subject later than expected by the subject to get the data, that is, the information flows late to the subject. In this article, we newly propose a time-based OI (TBOI) protocol to prevent not only illegal information flow but also late information flow. Here, operations implying illegal or late information flow are interrupted, that is, not performed at devices. In the evaluation, we show not only illegal information flow but also late information flow are prevented in the TBOI protocol differently from the OI protocol.\",\n \"Title: A comparison study of chi-square and uniform distributions of mesh clients for different router replacement methods using WMN-PSODGA hybrid intelligent simulation system\\nYear: 2021\\n\\nAbstract: Wireless Mesh Networks (WMNs) are gaining a lot of attention from researchers due to their advantages such as easy maintenance, low upfront cost and high robustness. Connectivity and stability directly affect the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO) and Distributed Genetic Algorithm (DGA), called WMN-PSODGA. In this paper, we compare chi-square and uniform distributions of mesh clients for different router replacement methods. The router replacement methods considered are Constriction Method (CM), Random Inertia Weight Method (RIWM), Linearly Decreasing Inertia Weight Method (LDIWM), Linearly Decreasing Vmax Method (LDVM) and Rational Decrement of Vmax Method (RDVM). The simulation results show that for chi-square distribution the mesh routers cover all mesh clients for all router replacement methods. In terms of load balancing, the method that achieves the best performance is RDVM. When using the uniform distribution, the mesh routers do not cover all mesh clients, but this distribution shows good load balancing for four router replacement methods, with RIWM showing the best performance. The only method that shows poor performance for this distribution is LDIWM. However, since not all mesh clients are covered when using uniform distribution, the best scenario is chi-square distribution of mesh clients with RDVM as a router replacement method.\",\n \"Title: Capability token selection algorithms to implement lightweight protocols\\nYear: 2022\\n\\nAbstract: The IoT (Internet of Things) is now one of the most significant infrastructure and has to be secure against malicious accesses. Especially, it is critical to make devices secure in the IoT. In the CBAC (Capability-Based Access Control) model adopted to the IoT, device owners issue subjects capability tokens, i.e. a set of access rights on objects in devices. Objects in devices are data resource manipulated by subjects. Data are exchanged among subjects and objects through manipulating objects. Here, if subjects attempt to manipulate objects in accordance with the capability tokens issued, the subjects can get data which the subjects are not authorized to get, i.e. illegal information flow and late information flow occur. In our previous studies, protocols are implemented to prevent both illegal and late types of information flows from occurring. Here, operations implying such information flows are interrupted. However, the request processing time gets longer as the number of capability tokens used increases. In this paper, an MRCTSD (Minimum Required Capability Token Selection for Devices) algorithm is newly proposed to reduce the number of capability tokens used. In the evaluation, it is shown that the request processing times and the numbers of capability tokens used in the lightweight protocols realized with the MRCTSD algorithm are shorter and smaller than the conventional protocols, respectively.\",\n \"Title: An energy-efficient quorum-based locking protocol by omitting meaningless methods on object replicas\\nYear: 2022\\n\\nAbstract: In current information systems, a huge number of IoT (Internet of Things) devices are interconnected with various kinds of networks like WiFi and 5G networks. A large volume of data is gathered into servers from a huge number of IoT devices and is manipulated to provide application services. Gathered data is encapsulated along with methods to manipulate the data as an object like a database system. In objectbased systems, each application is composed of multiple objects. In addition, each object is replicated on multiple physical servers in order to increase availability, reliability, and performance of an application service. On the other hand, replicas of each object is required to be mutually consistent in presence of multiple transactions. Here, a larger amount of electric energy and computation resources are consumed in physical servers than non-replication approaches to serialize conflicting transactions on multiple replicas. Many algorithms to synchronize conflicting transactions are so far proposed like 2PL (Two-Phase Locking) and TO (Timestamp Ordering). However, the electric energy consumption is not considered. In this paper, an EEQBL-OMM (Energy-Efficient Quorum-Based Locking with Omitting Meaningless Method) protocol is newly proposed to reduce not only the average execution time of each transaction but also the total electric energy consumption of servers by omitting the execution of meaningless methods on replicas of each object. Evaluation results show the total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted instances of transactions in the EEQBL-OMM protocol can be on average reduced to 79%, 62%, and 80% of the ECLBQS (Energy Consumption Laxity-Based Quorum Selection) protocol which is proposed in our previous studies in a homogeneous set of servers, respectively. In addition, the evaluation results show the total electric energy consumption of servers, the average execution time of each transaction, and the number of aborted instances of transactions in the EEQBL-OMM protocol can be on average reduced to 73%, 50%, and 67% of the ECLBQS protocol in a heterogeneous set of servers, respectively. The evaluation results also show at most 48% and 51% of the total number of methods can be omitted as meaningless methods in a homogeneous set and heterogeneous set of servers, respectively, in the EEQBL-OMM protocol.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":56,"string":"56"}}},{"rowIdx":57,"cells":{"question_id":{"kind":"string","value":"Nianwen Xue"},"question":{"kind":"string","value":"Generate an abstract for the title \"Joint Pos Tagging And Transition-Based Constituent Parsing In Chinese With Non-Local Features\" using the following items: 1. Transition-based constituent parsers.\n2. POS tagging in syntactic parsing.\n3. Parser states alignment.\n4. Non-local and semi-supervised word cluster features.\n5. Improved parsing performance."},"answer":{"kind":"string","value":"We propose three improvements to address the drawbacks of state-of-the-art transition-based constituent parsers. First, to resolve the error propagation problem of the traditional pipeline approach, we incorporate POS tagging into the syntactic parsing process. Second, to alleviate the negative influence of size differences among competing action sequences, we align parser states during beam-search decoding. Third, to enhance the power of parsing models, we enlarge the feature set with non-local features and semi-supervised word cluster features. Experimental results show that these modifications improve parsing performance significantly. Evaluated on the Chinese TreeBank (CTB), our final performance reaches 86.3% (F1) when trained on CTB 5.1, and 87.1% when trained on CTB 6.0, and these results outperform all state-of-the-art parsers."},"correct_answer":{"kind":"string","value":"We propose three improvements to address the drawbacks of state-of-the-art transition-based constituent parsers. First, to resolve the error propagation problem of the traditional pipeline approach, we incorporate POS tagging into the syntactic parsing process. Second, to alleviate the negative influence of size differences among competing action sequences, we align parser states during beam-search decoding. Third, to enhance the power of parsing models, we enlarge the feature set with non-local features and semi-supervised word cluster features. Experimental results show that these modifications improve parsing performance significantly. Evaluated on the Chinese TreeBank (CTB), our final performance reaches 86.3% (F1) when trained on CTB 5.1, and 87.1% when trained on CTB 6.0, and these results outperform all state-of-the-art parsers."},"documents":{"kind":"list like","value":["Title: Applying syntactic, semantic and discourse constraints in Chinese temporal annotation\nYear: 2010\n\nAbstract: We describe a Chinese temporal annotation experiment that produced a sizable data set for the TempEval-2 evaluation campaign. We show that while we have achieved high inter-annotator agreement for simpler tasks such as identification of events and time expressions, temporal relation annotation proves to be much more challenging. We show that in order to improve the inter-annotator agreement it is important to strategically select the annotation targets, and the selection of annotation targets should be subject to syntactic, semantic and discourse constraints.","Title: Chinese Word Segmentation as Character Tagging\nYear: 2003\n\nAbstract: In this paper we report results of a supervised machine-learning approach to Chinese word segmentation. A maximum entropy tagger is trained on manually annotated data to automatically assign to Chinese characters, or hanzi, tags that indicate the position of a hanzi within a word. The tagged output is then converted into segmented text for evaluation. Preliminary results show that this approach is competitive against other supervised machine-learning segmenters reported in previous studies, achieving precision and recall rates of 95.01% and 94.94% respectively, trained on a 237K-word training set.","Title: Chinese word segmentation as LMR tagging\nYear: 2003\n\nAbstract: In this paper we present Chinese word segmentation algorithms based on the so-called LMR tagging. Our LMR taggers are implemented with the Maximum Entropy Markov Model and we then use Transformation-Based Learning to combine the results of the two LMR taggers that scan the input in opposite directions. Our system achieves F-scores of 95.9% and 91.6% on the Academia Sinica corpus and the Hong Kong City University corpus respectively.","Title: PropBank annotation of multilingual light verb constructions\nYear: 2010\n\nAbstract: In this paper, we have addressed the task of PropBank annotation of light verb constructions, which like multi-word expressions pose special problems. To arrive at a solution, we have evaluated 3 different possible methods of annotation. The final method involves three passes: (1) manual identification of a light verb construction, (2) annotation based on the light verb construction's Frame File, and (3) a deterministic merging of the first two passes. We also discuss how in various languages the light verb constructions are identified and can be distinguished from the non-light verb word groupings.","Title: Discourse-constrained temporal annotation\nYear: 2011\n\nAbstract: We describe an experiment on a temporal ordering task in this paper. We show that by selecting event pairs based on discourse structure and by modifying the pre-existent temporal classification scheme to fit the data better, we significantly improve inter-annotator agreement, as well as broaden the coverage of the task. We also present analysis of the current temporal classification scheme and propose ways to improve it in future work.","Title: OntoNotes: the 90% solution\nYear: 2009\n\nAbstract: OntoNotes is a five year multi-site collaboration between BBN Technologies, Information Sciences Institute of University of Southern California, University of Colorado, University of Pennsylvania and Brandeis University. The goal of the OntoNotes project is to provide linguistic data annotated with a skeletal representation of the literal meaning of sentences including syntactic parse, predicate-argument structure, coreference, and word senses linked to an ontology, allowing a new generation of language understanding technologies to be developed with new functional capabilities.","Title: Developing Guidelines and Ensuring Consistency for Chinese Text Annotation\nYear: 2000\n\nAbstract: With growing interest in Chinese Language Processing, numerous NLP tools (e.g. word segmenters, part-of-speech taggers, and parsers)for Chinese have been developed all over the world. However, since no large-scale bracketed corpora are available to the public, thesetools are trained on the corpora with different segmentation criteria, part-of-speech tagsets and bracketing guidelines, and therefore,comparisons are difficult. As a first step towards addressing this issue, we have been...","Title: A Machine Learning-Based Coreference Detection System for OntoNotes.\nYear: 2011\n\nAbstract: In this paper, we describe the algorithms and experimental results of Brandeis University in the participation of the CoNLL Task 2011 closed track. We report the features used in our system, and describe a novel cluster-based chaining algorithm to improve performance of coreference identification. We evaluate the system using the OntoNotes data set and describe our results.","Title: Annotating the propositions in the Penn Chinese Treebank\nYear: 2003\n\nAbstract: In this paper, we describe an approach to annotate the propositions in the Penn Chinese Treebank. We describe how diathesis alternation patterns can be used to make coarse sense distinctions for Chinese verbs as a necessary step in annotating the predicate-structure of Chinese verbs. We then discuss the representation scheme we use to label the semantic arguments and adjuncts of the predicates. We discuss several complications for this type of annotation and describe our solutions. We then discuss how a lexical database with predicate-argument structure information can be used to ensure consistent annotation. Finally, we discuss possible applications for this resource.","Title: The CoNLL-2009 shared task: syntactic and semantic dependencies in multiple languages\nYear: 2009\n\nAbstract: For the 11th straight year, the Conference on Computational Natural Language Learning has been accompanied by a shared task whose purpose is to promote natural language processing applications and evaluate them in a standard setting. In 2009, the shared task was dedicated to the joint parsing of syntactic and semantic dependencies in multiple languages. This shared task combines the shared tasks of the previous five years under a unique dependency-based formalism similar to the 2008 task. In this paper, we define the shared task, describe how the data sets were created and show their quantitative properties, report the results and summarize the approaches of the participating systems.","Title: Using parallel PropBanks to enhance word-alignments\nYear: 2009\n\nAbstract: This short paper describes the use of the linguistic annotation available in parallel PropBanks (Chinese and English) for the enhancement of automatically derived word alignments. Specifically, we suggest ways to refine and expand word alignments for verb-predicates by using predicate-argument structures. Evaluations demonstrate improved alignment accuracies that vary by corpus type.","Title: Aligning features with sense distinction dimensions\nYear: 2006\n\nAbstract: In this paper we present word sense disambiguation (WSD) experiments on ten highly polysemous verbs in Chinese, where significant performance improvements are achieved using rich linguistic features. Our system performs significantly better, and in some cases substantially better, than the baseline on all ten verbs. Our results also demonstrate that features extracted from the output of an automatic Chinese semantic role labeling system in general benefited the WSD system, even though the amount of improvement was not consistent across the verbs. For a few verbs, semantic role information actually hurt WSD performance. The inconsistency of feature performance is a general characteristic of the WSD task, as has been observed by others. We argue that this result can be explained by the fact that word senses are partitioned along different dimensions for different verbs and the features therefore need to be tailored to particular verbs in order to achieve adequate accuracy on verb sense disambiguation.","Title: Exploring temporal vagueness with mechanical turk\nYear: 2012\n\nAbstract: This paper proposes schematic changes to the TempEval framework that target the temporal vagueness problem. Specifically, two elements of vagueness are singled out for special treatment: vague time expressions, and explicit/implicit temporal modification of events. As proof of concept, an annotation experiment on explicit/implicit modification is conducted on Amazon's Mechanical Turk. Results show that the quality of a considerable segment of the annotation is comparable to annotation obtained in the traditional double-blind setting, only with higher coverage. This approach offers additional flexibility in how the temporal annotation data can be used.","Title: Automatic inference of the temporal location of situations in Chinese text\nYear: 2008\n\nAbstract: Chinese is a language that does not have morphological tense markers that provide explicit grammaticalization of the temporal location of situations (events or states). However, in many NLP applications such as Machine Translation, Information Extraction and Question Answering, it is desirable to make the temporal location of the situations explicit. We describe a machine learning framework where different sources of information can be combined to predict the temporal location of situations in Chinese text. Our experiments show that this approach significantly outperforms the most frequent tense baseline. More importantly, the high training accuracy shows promise that this challenging problem is solvable to a level where it can be used in practical NLP applications with more training data, better modeling techniques and more informative and generalizable features.","Title: Buy one get one free: Distant annotation of Chinese tense, event type and modality.\nYear: 2014\n\nAbstract: We describe a \"distant annotation\" method where we mark up the semantic tense, event type, and modality of Chinese events via a word-aligned parallel corpus. We first map Chinese verbs to their English counterparts via word alignment, and then annotate the resulting English text spans with coarse-grained categories for semantic tense, event type, and modality that we believe apply to both English and Chinese. Because English has richer morpho-syntactic indicators for semantic tense, event type and modality than Chinese, our intuition is that this distant annotation approach will yield more consistent annotation than if we annotate the Chinese side directly. We report experimental results that show stable annotation agreement statistics and that event type and modality have significant influence on tense prediction. We also report the size of the annotated corpus that we have obtained, and how different domains impact annotation consistency.","Title: Chinese sentence segmentation as comma classification\nYear: 2011\n\nAbstract: We describe a method for disambiguating Chinese commas that is central to Chinese sentence segmentation. Chinese sentence segmentation is viewed as the detection of loosely coordinated clauses separated by commas. Trained and tested on data derived from the Chinese Treebank, our model achieves a classification accuracy of close to 90% overall, which translates to an F1 score of 70% for detecting commas that signal sentence boundaries.","Title: Annotating the Predicate-Argument Structure of Chinese Nominalizations\nYear: 2006\n\nAbstract: Abstract This paper describes the Chinese NomBank Project, the goal of which is to annotate the predicate-argument structure of nominalized predicates in Chinese. The Chinese Nombank,extends the general framework,of the English and Chinese Proposition Banks to the annotation of nominalized,predicates and adds a layer of semantic annotation to the Chinese Treebank. We first outline the scope of the work by discussing the markability of the nominalized,predicates and their arguments. We then attempt to provide a categorization of the distribution of the arguments,of nominalized predicates. We also discuss the relevance of the event/result distinction to the annotation of nominalized,predicates and the phenomenon,of incorporation. Finally we discuss some cross-linguistic differences between,English and Chinese.","Title: Calibrating Features for Semantic Role Labeling\nYear: 2004\n\nAbstract: This paper takes a critical look at the features used in the semantic role tagging literature and show that the information in the input, gener- ally a syntactic parse tree, has yet to be fully exploited. We propose an additional set of fea- tures and our experiments show that these fea- tures lead to fairly signicant improvements in the tasks we performed. We further show that dierent features are needed for dierent sub- tasks. Finally, we show that by using a Maxi- mum Entropy classier and fewer features, we achieved results comparable with the best previ- ously reported results obtained with SVM mod- els. We believe this is a clear indication that developing features that capture the right kind of information is crucial to advancing the state- of-the-art in semantic analysis.","Title: Automatic semantic role labeling for Chinese verbs\nYear: 2005\n\nAbstract: Recent years have seen a revived interest in semantic parsing by applying statistical and machine-learning methods to semantically annotated corpora such as the FrameNet and the Proposition Bank. So far much of the research has been focused on English due to the lack of semantically annotated resources in other languages. In this paper, we report first results on semantic role labeling using a pre-release version of the Chinese Proposition Bank. Since the Chinese Proposition Bank is superimposed on top of the Chinese Tree-bank, i.e., the semantic role labels are assigned to constituents in a treebank parse tree, we start by reporting results on experiments using the handcrafted parses in the treebank. This will give us a measure of the extent to which the semantic role labels can be bootstrapped from the syntactic annotation in the treebank. We will then report experiments using a fully automatic Chinese parser that integrates word segmentation, POS-tagging and parsing. This will gauge how successful semantic role labeling can be done for Chinese in realistic situations. We show that our results using hand-crafted parses are slightly higher than the results reported for the state-of-the-art semantic role labeling systems for English using the Penn English Proposition Bank data, even though the Chinese Proposition Bank is smaller in size. When an automatic parser is used, however, the accuracy of our system is much lower than the English state-of-the-art. This reveals an interesting cross-linguistic difference between the two languages, which we attempt to explain. We also describe a method to induce verb classes from the Proposition Bank \"frame files\" that can be used to improve semantic role labeling.","Title: Adding semantic roles to the chinese treebank\nYear: 2009\n\nAbstract: We report work on adding semantic role labels to the Chinese Treebank, a corpus already annotated with phrase structures. The work involves locating all verbs and their nominalizations in the corpus, and semi-automatically adding semantic role labels to their arguments, which are constituents in a parse tree. Although the same procedure is followed, different issues arise in the annotation of verbs and nominalized predicates. For verbs, identifying their arguments is generally straightforward given their syntactic structure in the Chinese Treebank as they tend to occupy well-defined syntactic positions. Our discussion focuses on the syntactic variations in the realization of the arguments as well as our approach to annotating dislocated and discontinuous arguments. In comparison, identifying the arguments for nominalized predicates is more challenging and we discuss criteria and procedures for distinguishing arguments from non-arguments. In particular we focus on the role of support verbs as well as the relevance of event/result distinctions in the annotation of the predicate-argument structure of nominalized predicates. We also present our approach to taking advantage of the syntactic structure in the Chinese Treebank to bootstrap the predicate-argument structure annotation of verbs. Finally, we discuss the creation of a lexical database of frame files and its role in guiding predicate-argument annotation. Procedures for ensuring annotation consistency and inter-annotator agreement evaluation results are also presented.","Title: Combining classifiers for Chinese word segmentation\nYear: 2002\n\nAbstract: In this paper we report results of a supervised machine-learning approach to Chinese word segmentation. First, a maximum entropy tagger is trained on manually annotated data to automatically labels the characters with tags that indicate the position of character within a word. An error-driven transformation-based tagger is then trained to clean up the tagging inconsistencies of the first tagger. The tagged output is then converted into segmented text. The preliminary results show that this approach is competitive compared with other supervised machine-learning segmenters reported in previous studies.","Title: Chinese comma disambiguation for discourse analysis\nYear: 2012\n\nAbstract: The Chinese comma signals the boundary of discourse units and also anchors discourse relations between adjacent text spans. In this work, we propose a discourse structure-oriented classification of the comma that can be automatically extracted from the Chinese Treebank based on syntactic patterns. We then experimented with two supervised learning methods that automatically disambiguate the Chinese comma based on this classification. The first method integrates comma classification into parsing, and the second method adopts a \"post-processing\" approach that extracts features from automatic parses to train a classifier. The experimental results show that the second approach compares favorably against the first approach.","Title: Automatic recognition of logical relations for English, Chinese and Japanese in the GLARF framework\nYear: 2009\n\nAbstract: We present GLARF, a framework for representing three linguistic levels and systems for generating this representation. We focus on a logical level, like LFG's F-structure, but compatible with Penn Treebanks. While less finegrained than typical semantic role labeling approaches, our logical structure has several advantages: (1) it includes all words in all sentences, regardless of part of speech or semantic domain; and (2) it is easier to produce accurately. Our systems achieve 90% for English/Japanese News and 74.5% for Chinese News -- these F-scores are nearly the same as those achieved for treebank-based parsing.","Title: Annotating discourse connectives in the Chinese Treebank\nYear: 2005\n\nAbstract: In this paper we examine the issues that arise from the annotation of the discourse connectives for the Chinese Discourse Treebank Project. This project is based on the same principles as the PDTB, a project that annotates the English discourse connectives in the Perm Treebank. The paper begins by outlining range of discourse connectives under consideration in this project and examines the distribution of the explicit discourse connectives. We then examine the types of syntactic units that can be arguments to the discourse connectives. We show that one of the most challenging issues in this type of discourse annotation is determining the textual spans of the arguments and this is partly due to the hierarchical nature of discourse relations. Finally, we discuss sense discrimination of the discourse connectives, which involves separating discourse connective from non-discourse connective senses and teasing apart the different discourse connective senses, and discourse connective variation, the use of different connectives to represent the same discourse relation.","Title: A parallel Proposition Bank II for Chinese and English\nYear: 2005\n\nAbstract: The Proposition Bank (PropBank) project is aimed at creating a corpus of text annotated with information about semantic propositions. The second phase of the project, PropBank II adds additional levels of semantic annotation which include eventuality variables, co-reference, coarse-grained sense tags, and discourse connectives. This paper presents the results of the parallel PropBank II project, which adds these richer layers of semantic annotation to the first 100K of the Chinese Treebank and its English translation. Our preliminary analysis supports the hypothesis that this additional annotation reconciles many of the surface differences between the two languages.","Title: Transducing logical relations from automatic and manual GLARF\nYear: 2009\n\nAbstract: GLARF relations are generated from treebank and parses for English, Chinese and Japanese. Our evaluation of system output for these input types requires consideration of multiple correct answers.","Title: PDTB-style discourse annotation of Chinese text\nYear: 2012\n\nAbstract: We describe a discourse annotation scheme for Chinese and report on the preliminary results. Our scheme, inspired by the Penn Discourse TreeBank (PDTB), adopts the lexically grounded approach; at the same time, it makes adaptations based on the linguistic and statistical characteristics of Chinese text. Annotation results show that these adaptations work well in practice. Our scheme, taken together with other PDTB-style schemes (e.g. for English, Turkish, Hindi, and Czech), affords a broader perspective on how the generalized lexically grounded approach can flesh itself out in the context of cross-linguistic annotation of discourse relations.","Title: Using a smoothing maximum entropy model for chinese nominal entity tagging\nYear: 2004\n\nAbstract: This paper treats nominal entity tagging as a six-way (five categories plus non-entity) classification problem and applies a smoothing maximum entropy (ME) model with a Gaussian prior to a Chinese nominal entity tagging task. The experimental results show that the model performs consistently better than an ME model using a simple count cut-off. The results also suggest that simple semantic features extracted from an electronic dictionary improve the model’s performance, especially when the training data is insufficient.","Title: Chasing the ghost: recovering empty categories in the Chinese treebank\nYear: 2010\n\nAbstract: Empty categories represent an important source of information in syntactic parses annotated in the generative linguistic tradition, but empty category recovery has only started to receive serious attention until very recently, after substantial progress in statistical parsing. This paper describes a unified framework in recovering empty categories in the Chinese Tree-bank. Our results show that given skeletal gold standard parses, the empty categories can be detected with very high accuracy. We report very promising results for empty category recovery for automatic parses as well.","Title: Semantic role labeling of nominalized predicates in Chinese\nYear: 2006\n\nAbstract: Recent work on semantic role labeling (SRL) has focused almost exclusively on the analysis of the predicate-argument structure of verbs, largely due to the lack of human-annotated resources for other types of predicates that can serve as training and test data for the semantic role labeling systems. However, it is well-known that verbs are not the only type of predicates that can take arguments. Most notably, nouns that are nominalized forms of verbs and relational nouns generally are also considered to have their own predicate-argument structure. In this paper we report results of SRL experiments on nominalized predicates in Chinese, using a newly completed corpus, the Chinese Nombank. We also discuss the impact of using publicly available manually annotated verb data to improve the SRL accuracy of nouns, exploiting a widely-held assumption that verbs and their nominalizations share the same predicate-argument structure. Finally, we discuss the results of applying reranking techniques to improve SRL accuracy for nominalized predicates, which showed insignificant improvement.","Title: Proposition Bank II: Delving Deeper\nYear: 2004\n\nAbstract: The PropBank project is creating a corpus of text annotated with information about basic semantic propositions. PropBank I (Kingsbury & Palmer, 2002) added a layer of predicate- argument information, or semantic roles, to the syntactic structures of the English Penn Treebank. This paper presents an overview of the second phase of PropBank Annotation, PropBank II, which is being applied to Eng- lish and Chinese, and includes (Neodavid- sonian) eventuality variables, nominal references, sense tagging, and connections to the Penn Discourse Treebank (PDTB), a pro- ject for annotating discourse connectives and their arguments.","Title: Bidirectional Sequence Labeling Via Dual Decomposition\nYear: 2013\n\nAbstract: In this paper, we propose a bidirectional algorithm for sequence labeling to capture the influence of both the left-to-right and the right-to-left directions. We combine the optimization of two unidirectional models from opposite directions via the dual decomposition method to jointly label the input sequence. Experiments on three sequence labeling tasks (Chinese word segmentation, English POS tagging and text chunking) show that our approach can improve the accuracy of sequence labeling tasks when the two unidirectional models individually make highly different predictions.","Title: Improving MT word alignment using aligned multi-stage parses\nYear: 2011\n\nAbstract: We use hand-coded rules and graph-aligned logical dependencies to reorder English text towards Chinese word order. We obtain a 1.5% higher F-score for Giza++ compared to running with unprocessed text. We describe this research and its implications for SMT.","Title: Not an Interlingua, But Close: Comparison of English AMRs to Chinese and Czech.\nYear: 2014\n\nAbstract: Meaning Representations (AMRs) are rooted, directional and labeled graphs that abstract away from morpho-syntactic idiosyncrasies such as word category (verbs and nouns), word order, and function words (determiners, some prepositions). Because these syntactic idiosyncrasies account for many of the cross-lingual differences, it would be interesting to see if this representation can serve, e.g., as a useful, minimally divergent transfer layer in machine translation. To answer this question, we have translated 100 English sentences that have existing AMRs into Chinese and Czech to create AMRs for them. A cross-linguistic comparison of English to Chinese and Czech AMRs reveals both cases where the AMRs for the language pairs align well structurally and cases of linguistic divergence. We found that the level of compatibility of AMR between English and Chinese is higher than between English and Czech. We believe this kind of comparison is beneficial to further refining the annotation standards for each of the three languages and will lead to more compatible annotation guidelines between the languages.","Title: Annotating dropped pronouns in Chinese newswire text.\nYear: 2012\n\nAbstract: We propose an annotation framework to explicitly identify dropped subject pronouns in Chinese. We acknowledge and specify 10 concrete pronouns that exist as words in Chinese and 4 abstract pronouns that do not correspond to Chinese words, but that are recognized conceptually, to native Chinese speakers. These abstract pronouns are identified as \"unspecified\", \"pleonastic\", \"event\", and \"existential\" and are argued to exist cross-linguistically. We trained two annotators, fluent in Chinese, and adjudicated their annotations to form a gold standard. We achieved an inter-annotator agreement kappa of .6 and an observed agreement of .7. We found that annotators had the most difficulty with the abstract pronouns, such as \"unspecified\" and \"event\", but we posit that further specification and training has the potential to significantly improve these results. We believe that this annotated data will serve to help improve Machine Translation models that translate from Chinese to a non pro-drop language, like English, that requires all subject pronouns to be explicit.","Title: Parallel Aligned Treebanks at LDC: New Challenges Interfacing Existing Infrastructures.\nYear: 2012\n\nAbstract: Parallel aligned treebanks (PAT) are linguistic corpora annotated with morphological and syntactic structures that are aligned at sentence as well as sub-sentence levels. They are valuable resources for improving machine translation (MT) quality. Recently, there has been an increasing demand for such data, especially for divergent language pairs. The Linguistic Data Consortium (LDC) and its academic partners have been developing Arabic-English and Chinese-English PATs for several years. This paper describes the PAT corpus creation effort for the program GALE (Global Autonomous Language Exploitation) and introduces the potential issues of scaling up this PAT effort for the program BOLT (Broad Operational Language Translation). Based on existing infrastructures and in the light of current annotation process, challenges and approaches, we are exploring new methodologies to address emerging challenges in constructing PATs, including data volume bottlenecks, dialect issues of Arabic languages, and new genre features related to rapidly changing social media. Preliminary experimental results are presented to show the feasibility of the approaches proposed.","Title: A corpus of full-text journal articles is a robust evaluation tool for revealing differences in performance of biomedical natural language processing tools.\nYear: 2012\n\nAbstract: We introduce the linguistic annotation of a corpus of 97 full-text biomedical publications, known as the Colorado Richly Annotated Full Text (CRAFT) corpus. We further assess the performance of existing tools for performing sentence splitting, tokenization, syntactic parsing, and named entity recognition on this corpus.Many biomedical natural language processing systems demonstrated large differences between their previously published results and their performance on the CRAFT corpus when tested with the publicly available models or rule sets. Trainable systems differed widely with respect to their ability to build high-performing models based on this data.The finding that some systems were able to train high-performing models based on this corpus is additional evidence, beyond high inter-annotator agreement, that the quality of the CRAFT corpus is high. The overall poor performance of various systems indicates that considerable work needs to be done to enable natural language processing systems to work well when the input is full-text journal articles. The CRAFT corpus provides a valuable resource to the biomedical natural language processing community for evaluation and training of new models for biomedical full text publications.","Title: Automatic predicate argument structure analysis of the Penn Chinese Treebank.\nYear: 2003\n\nAbstract: Recent work in machine translation and information extraction has demonstrated the utility of a level that represents the predicate-argument structure. It would be especially useful for machine translation to have two such Proposition Banks, one for each language under consideration. A Proposition Bank for English has been developed over the last few years, and we describe here our development of a tool for facilitating the development of a Chinese Proposition Bank. We also discuss some issues specific to the Chinese Treebank that complicate the matter of mapping syntactic representation to a predicate-argument level, and report on some preliminary evaluation of the accuracy of the semantic tagging tool.","Title: Temporal relation discovery between events and temporal expressions identified in clinical narrative.\nYear: 2013\n\nAbstract: The automatic detection of temporal relations between events in electronic medical records has the potential to greatly augment the value of such records for understanding disease progression and patients' responses to treatments. We present a three-step methodology for labeling temporal relations using machine learning and deterministic rules over an annotated corpus provided by the 2012 i2b2 Shared Challenge. We first create an expanded training network of relations by computing the transitive closure over the annotated data; we then apply hand-written rules and machine learning with a feature set that casts a wide net across potentially relevant lexical and syntactic information; finally, we employ a voting mechanism to resolve global contradictions between the local predictions made by the learned classifier. Results over the testing data illustrate the contributions of initial prediction and conflict resolution.","Title: A Chinese semantic lexicon of senses and roles\nYear: 2006\n\nAbstract: We describe a Chinese lexical semantic resource that consists of 11,765 predicates (mostly verbs and their nominalizations)\n analyzed with coarse-grained senses and semantic roles. We show that distinguishing senses at a coarse-grained level is a\n necessary part of specifying the semantic roles and describe our strategies for sense determination for purposes of predicate-argument\n structure specification. The semantic roles are postulated to account for syntactic variations, the different ways in which\n the semantic roles of a predicate are realized. The immediate purpose for this lexical semantic resource is to support the\n annotation of the Chinese PropBank, but we believe it can also serve as stepping stone for higher-level semantic generalizations.","Title: Labeling chinese predicates with semantic roles\nYear: 2008\n\nAbstract: In this article we report work on Chinese semantic role labeling, taking advantage of two recently completed corpora, the Chinese PropBank, a semantically annotated corpus of Chinese verbs, and the Chinese Nombank, a companion corpus that annotates the predicate-argument structure of nominalized predicates. Because the semantic role labels are assigned to the constituents in a parse tree, we first report experiments in which semantic role labels are automatically assigned to hand-crafted parses in the Chinese Treebank. This gives us a measure of the extent to which semantic role labels can be bootstrapped from the syntactic annotation provided in the treebank. We then report experiments using automatic parses with decreasing levels of human annotation in the input to the syntactic parser: parses that use gold-standard segmentation and POS-tagging, parses that use only gold-standard segmentation, and fully automatic parses. These experiments gauge how successful semantic role labeling for Chinese can be in more realistic situations. Our results show that when hand-crafted parses are used, semantic role labeling accuracy for Chinese is comparable to what has been reported for the state-of-the-art English semantic role labeling systems trained and tested on the English PropBank, even though the Chinese PropBank is significantly smaller in size. When an automatic parser is used, however, the accuracy of our system is significantly lower than the English state of the art. This indicates that an improvement in Chinese parsing is critical to high-performance semantic role labeling for Chinese.","Title: CoNLL-2011 Shared Task: Modeling Unrestricted Coreference in OntoNotes.\nYear: 2011\n\nAbstract: The CoNLL-2011 shared task involved predicting coreference using OntoNotes data. Resources in this field have tended to be limited to noun phrase coreference, often on a restricted set of entities, such as ace entities. OntoNotes provides a large-scale corpus of general anaphoric coreference not restricted to noun phrases or to a specified set of entity types. OntoNotes also provides additional layers of integrated annotation, capturing additional shallow semantic structure. This paper briefly describes the OntoNotes annotation (coreference and other layers) and then describes the parameters of the shared task including the format, pre-processing information, and evaluation criteria, and presents and discusses the results achieved by the participating systems. Having a standard test set and evaluation parameters, all based on a new resource that provides multiple integrated annotation layers (parses, semantic roles, word senses, named entities and coreference) that could support joint models, should help to energize ongoing research in the task of entity and event coreference.","Title: Annotating \"tense\" in a Tense-less Language\nYear: 2008\n\nAbstract: In the context of Natural Language Processing, annotation is about recovering implicit information that is useful for natural language applications. In this paper we describe a \"tense\" annotation task for Chinese, a language that does not have grammatical tense, that is designed to infer the temporal location of a situation in relation to the temporal deixis, the moment of speech. If successful, this would be a highly rewarding endeavor as it has application in many natural language systems. Our preliminary experiments show that while this is a very challenging annotation task for which high annotation consistency is very difficult but not impossible to achieve. We show that guidelines that provide a conceptually intuitive framework will be crucial to the success of this annotation effort.","Title: The Chinese Discourse TreeBank: a Chinese corpus annotated with discourse relations\nYear: 2015\n\nAbstract: The paper presents the Chinese Discourse TreeBank, a corpus annotated with Penn Discourse TreeBank style discourse relations that take the form of a predicate taking two arguments. We first characterize the syntactic and statistical distributions of Chinese discourse connectives as well as the role of Chinese punctuation marks in discourse annotation, and then describe how we design our annotation strategy procedure based on this characterization. The Chinese-specific features of our annotation strategy include annotating explicit and implicit discourse relations in one single pass, defining the argument labels on semantic, rather than syntactic, grounds, as well as annotating the semantic type of implicit discourse relations directly. We also introduce a flat, 11-valued semantic type classification scheme for discourse relations. We finally demonstrate the feasibility of our approach with evaluation results.","Title: Effective Document-Level Features For Chinese Patent Word Segmentation\nYear: 2014\n\nAbstract: A patent is a property right for an invention granted by the government to the inventor. Patents often have a high concentration of scientific and technical terms that are rare in everyday language. However, some scientific and technical terms usually appear with high frequency only in one specific patent. In this paper, we propose a pragmatic approach to Chinese word segmentation on patents where we train a sequence labeling model based on a group of novel document-level features. Experiments show that the accuracy of our model reached 96.3% (F-1 score) on the development set and 95.0% on a held-out test set.","Title: Feature Optimization For Constituent Parsing Via Neural Networks\nYear: 2015\n\nAbstract: The performance of discriminative constituent parsing relies crucially on feature engineering, and effective features usually have to be carefully selected through a painful manual process. In this paper, we propose to automatically learn a set of effective features via neural networks. Specifically, we build a feedforward neural network model, which takes as input a few primitive units (words, POS tags and certain contextual tokens) from the local context, induces the feature representation in the hidden layer and makes parsing predictions in the output layer. The network simultaneously learns the feature representation and the prediction model parameters using a back propagation algorithm. By pre-training the model on a large amount of automatically parsed data, and then fine-tuning on the manually annotated Treebank data, our parser achieves the highest F-1 score at 86.6% on Chinese Treebank 5.1, and a competitive F-1 score at 90.7% on English Treebank. More importantly, our parser generalizes well on cross-domain test sets, where we significantly outperform Berkeley parser by 3.4 points on average for Chinese and 2.5 points for English.","Title: Recovering Dropped Pronouns From Chinese Text Messages\nYear: 2015\n\nAbstract: Pronouns are frequently dropped in Chinese sentences, especially in informal data such as text messages. In this work we propose a solution to recover dropped pronouns in SMS data. We manually annotate dropped pronouns in 684 SMS files and apply machine learning algorithms to recover them, leveraging lexical, contextual and syntactic information as features. We believe this is the first work on recovering dropped pronouns in Chinese text messages.","Title: Boosting Transition-Based Amr Parsing With Refined Actions And Auxiliary Analyzers\nYear: 2015\n\nAbstract: We report improved AMR parsing results by adding a new action to a transition-based AMR parser to infer abstract concepts and by incorporating richer features produced by auxiliary analyzers such as a semantic role labeler and a coreference resolver. We report final AMR parsing results that show an improvement of 7% absolute in F-1 score over the best previously reported result. Our parser is available at: https://github.com/Juicechuan/AMRParsing","Title: A Transition-based Algorithm for AMR Parsing.\nYear: 2015\n\nAbstract: We present a two-stage framework to parse a sentence into its Abstract Meaning Representation (AMR). We first use a dependency parser to generate a dependency tree for the sentence. In the second stage, we design a novel transition-based algorithm that transforms the dependency tree to an AMR graph. There are several advantages with this approach. First, the dependency parser can be trained on a training set much larger than the training set for the tree-to-graph algorithm, resulting in a more accurate AMR parser overall. Our parser yields an improvement of 5% absolute in F-measure over the best previous result. Second, the actions that we design are linguistically intuitive and capture the regularities in the mapping between the dependency structure and the AMR of a sentence. Third, our parser runs in nearly linear time in practice in spite of a worst-case complexity ofO(n 2 ).","Title: Improving the Inference of Implicit Discourse Relations via Classifying Explicit Discourse Connectives.\nYear: 2015\n\nAbstract: Discourse relation classification is an important component for automatic discourse parsing and natural language understanding. The performance bottleneck of a discourse parser comes from implicit discourse relations, whose discourse connectives are not overtly present. Explicit discourse connectives can potentially be exploited to collect more training data to collect more data and boost the performance. However, using them indiscriminately has been shown to hurt the performance because not all discourse connectives can be dropped arbitrarily. Based on this insight, we investigate the interaction between discourse connectives and the discourse relations and propose the criteria for selecting the discourse connectives that can be dropped independently of the context without changing the interpretation of the discourse. Extra training data collected only by the freely omissible connectives improve the performance of the system without additional features.","Title: Neural Network Models for Implicit Discourse Relation Classification in English and Chinese without Surface Features.\nYear: 2016\n\nAbstract: Inferring implicit discourse relations in natural language text is the most difficult subtask in discourse parsing. Surface features achieve good performance, but they are not readily applicable to other languages without semantic lexicons. Previous neural models require parses, surface features, or a small label set to work well. Here, we propose neural network models that are based on feedforward and long-short term memory architecture without any surface features. To our surprise, our best configured feedforward architecture outperforms LSTM-based model in most cases despite thorough tuning. Under various fine-grained label sets and a cross-linguistic setting, our feedforward models perform consistently better or at least just as well as systems that require hand-crafted surface features. Our models present the first neural Chinese discourse parser in the style of Chinese Discourse Treebank, showing that our results hold cross-linguistically.","Title: Large Multi-lingual, Multi-level and Multi-genre Annotation Corpus.\nYear: 2016\n\nAbstract: High accuracy for automated translation and information retrieval calls for linguistic annotations at various language levels. The plethora of informal internet content sparked the demand for porting state-of-art natural language processing (NLP) applications to new social media as well as diverse language adaptation. Effort launched by the BOLT (Broad Operational Language Translation) program at DARPA (Defense Advanced Research Projects Agency) successfully addressed the internet information with enhanced NLP systems. BOLT aims for automated translation and linguistic analysis for informal genres of text and speech in online and in-person communication. As a part of this program, the Linguistic Data Consortium (LDC) developed valuable linguistic resources in support of the training and evaluation of such new technologies. This paper focuses on methodologies, infrastructure, and procedure for developing linguistic annotation at various language levels, including Treebank (TB), word alignment (WA), PropBank (PB), and co-reference (CoRef). Inspired by the OntoNotes approach with adaptations to the tasks to reflect the goals and scope of the BOLT project, this effort has introduced more annotation types of informal and free-style genres in English, Chinese and Egyptian Arabic. The corpus produced is by far the largest multi-lingual, multi-level and multi-genre annotation corpus of informal text and speech.","Title: Generalizing the semantic roles in the Chinese Proposition Bank.\nYear: 2016\n\nAbstract: The Chinese Proposition Bank (CPB) is a corpus annotated with semantic roles for the arguments of verbal and nominalized predicates. The semantic roles for the core arguments are defined in a predicate-specific manner. That is, a set of semantic roles, numerically identified, are defined for each sense of a predicate lemma and recorded in a valency lexicon called frame files. The predicate-specific manner in which the semantic roles are defined reduces the cognitive burden on the annotators since they only need to internalize a few roles at a time and this has contributed to the consistency in annotation. It was also a sensible approach given the contentious issue of how many semantic roles are needed if one were to adopt of set of global semantic roles that apply to all predicates. A downside of this approach, however, is that the predicate-specific roles may not be consistent across predicates, and this inconsistency has a negative impact on training automatic systems. Given the progress that has been made in defining semantic roles in the last decade or so, time is ripe for adopting a set of general semantic roles. In this article, we describe our effort to \\\"re-annotate\\\" the CPB with a set of \\\"global\\\" semantic roles that are predicate-independent and investigate their impact on automatic semantic role labeling systems. When defining these global semantic roles, we strive to make them compatible with a recently published ISO standards on the annotation of semantic roles (ISO 24617-4:2014 SemAF-SR) while taking the linguistic characteristics of the Chinese language into account. We show that in spite of the much larger number of global semantic roles, the accuracy of an off-the-shelf semantic role labeling system retrained on the data re-annotated with global semantic roles is comparable to that trained on the data set with the original predicate-specific semantic roles. We also argue that the re-annotated data set, together with the original data, provides the user with more flexibility when using the corpus.","Title: CoNLL 2016 Shared Task on Multilingual Shallow Discourse Parsing.\nYear: 2016\n\nAbstract: The CoNLL-2016 Shared Task is the second edition of the CoNLL-2015 Shared Task, now on Multilingual Shallow discourse parsing. Similar to the 2015 task, the goal of the shared task is to identify individual discourse relations that are present in natural language text. Given a natural language text, participating teams are asked to locate the discourse connectives (explicit or implicit) and their arguments as well as predicting the sense of the discourse connectives. Based on the success of the previous year, we continued to ask participants to deploy their systems on TIRA, a web-based platform on which participants can run their systems on the test data for evaluation. This evaluation methodology preserves the integrity of the shared task. We have also made a few changes and additions in the 2016 shared task based on the feedback from 2015. The first is that teams could choose to carry out the task on Chinese texts, or English texts, or both. We have also allowed participants to focus on parts of the shared task (rather than the whole thing) as a typical system requires substantial investment of effort. Finally, we have modified the scorer so that it can report results based on partial matches of the arguments. 23 teams participated in this year’s shared task, using a wide variety of approaches. In this overview paper, we present the task definition, the training and test sets, and the evaluation protocol and metric used during this shared task. We also summarize the different approaches adopted by the participating teams, and present the evaluation results. The evaluation data sets and the scorer will serve as a benchmark for future research on shallow discourse parsing.","Title: Towards Accurate Word Segmentation for Chinese Patents.\nYear: 2016\n\nAbstract: A patent is a property right for an invention granted by the government to the inventor. An invention is a solution to a specific technological problem. So patents often have a high concentration of scientific and technical terms that are rare in everyday language. The Chinese word segmentation model trained on currently available everyday language data sets performs poorly because it cannot effectively recognize these scientific and technical terms. In this paper we describe a pragmatic approach to Chinese word segmentation on patents where we train a character-based semi-supervised sequence labeling model by extracting features from a manually segmented corpus of 142 patents, enhanced with information extracted from the Chinese TreeBank. Experiments show that the accuracy of our model reached 95.08% (F1 score) on a held-out test set and 96.59% on development set, compared with an F1 score of 91.48% on development set if the model is trained on the Chinese TreeBank. We also experimented with some existing domain adaptation techniques, the results show that the amount of target domain data and the selected features impact the performance of the domain adaptation techniques.","Title: Addressing the Data Sparsity Issue in Neural AMR Parsing.\nYear: 2017\n\nAbstract: Neural attention models have achieved great success in different NLP tasks. How- ever, they have not fulfilled their promise on the AMR parsing task due to the data sparsity issue. In this paper, we de- scribe a sequence-to-sequence model for AMR parsing and present different ways to tackle the data sparsity problem. We show that our methods achieve significant improvement over a baseline neural atten- tion model and our results are also compet- itive against state-of-the-art systems that do not use extra linguistic resources.","Title: Translation Divergences in Chinese-English Machine Translation: An Empirical Investigation.\nYear: 2017\n\nAbstract: In this article, we conduct an empirical investigation of translation divergences between Chinese and English relying on a parallel treebank. To do this, we first devise a hierarchical alignment scheme where Chinese and English parse trees are aligned in a way that eliminates conflicts and redundancies between word alignments and syntactic parses to prevent the generation of spurious translation divergences. Using this Hierarchically Aligned Chinese-English Parallel Treebank HACEPT, we are able to semi-automatically identify and categorize the translation divergences between the two languages and quantify each type of translation divergence. Our results show that the translation divergences are much broader than described in previous studies that are largely based on anecdotal evidence and linguistic knowledge. The distribution of the translation divergences also shows that some high-profile translation divergences that motivate previous research are actually very rare in our data, whereas other translation divergences that have previously received little attention actually exist in large quantities. We also show that HACEPT allows the extraction of syntax-based translation rules, most of which are expressive enough to capture the translation divergences, and point out that the syntactic annotation in existing treebanks is not optimal for extracting such translation rules. We also discuss the implications of our study for attempts to bridge translation divergences by devising shared semantic representations across languages. Our quantitative results lend further support to the observation that although it is possible to bridge some translation divergences with semantic representations, other translation divergences are open-ended, thus building a semantic representation that captures all possible translation divergences may be impractical.","Title: Structured Interpretation of Temporal Relations.\nYear: 2018\n\nAbstract: Temporal relations between events and time expressions in a document are often modeled in an unstructured manner where relations between individual pairs of time expressions and events are considered in isolation. This often results in inconsistent and incomplete annotation and computational modeling. We propose a novel annotation approach where events and time expressions in a document form a dependency tree in which each dependency relation corresponds to an instance of temporal anaphora where the antecedent is the parent and the anaphor is the child. We annotate a corpus of 235 documents using this approach in the two genres of news and narratives, with 48 documents doubly annotated. We report a stable and high inter-annotator agreement on the doubly annotated subset, validating our approach, and perform a quantitative comparison between the two genres of the entire corpus. We make this corpus publicly available.","Title: Neural Ranking Models for Temporal Dependency Structure Parsing.\nYear: 2018\n\nAbstract: We design and build the first neural temporal dependency parser. It utilizes a neural ranking model with minimal feature engineering, and parses time expressions and events in a text into a temporal dependency tree structure. We evaluate our parser on two domains: news reports and narrative stories. In a parsing-only evaluation setup where gold time expressions and events are provided, our parser reaches 0.81 and 0.70 f-score on unlabeled and labeled parsing respectively, a result that is very competitive against alternative approaches. In an end-to-end evaluation setup where time expressions and events are automatically recognized, our parser beats two strong baselines on both data domains. Our experimental results and discussions shed light on the nature of temporal dependency structures in different domains and provide insights that we believe will be valuable to future research in this area.","Title: A Survey of Discourse Representations for Chinese Discourse Annotation\nYear: 2019\n\nAbstract: A key element in computational discourse analysis is the design of a formal representation for the discourse structure of a text. With machine learning being the dominant method, it is important to identify a discourse representation that can be used to perform large-scale annotation. This survey provides a systematic analysis of existing discourse representation theories to evaluate whether they are suitable for annotation of Chinese text. Specifically, the two properties, expressiveness and practicality, are introduced to compare the representations of theories based on rhetorical relations and the representations of theories based on entity relations. The comparison systematically reveals linguistic and computational characteristics of the theories. After that, we conclude that none of the existing theories are quite suitable for scalable Chinese discourse annotation because they are not both expressive and practical. Therefore, a new discourse representation needs to be proposed, which should balance the expressiveness and practicality, and cover rhetorical relations and entity relations. Inspired by the conclusions, this survey discusses some preliminary proposals on how to represent the discourse structure that are worth pursuing.","Title: Recovering Dropped Pronouns in Chinese Conversations via Modeling Their Referents.\nYear: 2019\n\nAbstract: Pronouns are often dropped in Chinese sentences, and this happens more frequently in conversational genres as their referents can be easily understood from context. Recovering dropped pronouns is essential to applications such as Information Extraction where the referents of these dropped pronouns need to be resolved, or Machine Translation when Chinese is the source language. In this work, we present a novel end-to-end neural network model to recover dropped pronouns in conversational data. Our model is based on a structured attention mechanism that models the referents of dropped pronouns utilizing both sentence-level and word-level information. Results on three different conversational genres show that our approach achieves a significant improvement over the current state of the art.","Title: UMR-Writer: A Web Application for Annotating Uniform Meaning Representations\nYear: 2021\n\nAbstract: We present UMR-Writer, a web-based application for annotating Uniform Meaning Representations (UMR), a graph-based, cross-linguistically applicable semantic representation developed recently to support the development of interpretable natural language applications that require deep semantic analysis of texts. We present the functionalities of UMR-Writer and discuss the challenges in developing such a tool and how they are addressed."],"string":"[\n \"Title: Applying syntactic, semantic and discourse constraints in Chinese temporal annotation\\nYear: 2010\\n\\nAbstract: We describe a Chinese temporal annotation experiment that produced a sizable data set for the TempEval-2 evaluation campaign. We show that while we have achieved high inter-annotator agreement for simpler tasks such as identification of events and time expressions, temporal relation annotation proves to be much more challenging. We show that in order to improve the inter-annotator agreement it is important to strategically select the annotation targets, and the selection of annotation targets should be subject to syntactic, semantic and discourse constraints.\",\n \"Title: Chinese Word Segmentation as Character Tagging\\nYear: 2003\\n\\nAbstract: In this paper we report results of a supervised machine-learning approach to Chinese word segmentation. A maximum entropy tagger is trained on manually annotated data to automatically assign to Chinese characters, or hanzi, tags that indicate the position of a hanzi within a word. The tagged output is then converted into segmented text for evaluation. Preliminary results show that this approach is competitive against other supervised machine-learning segmenters reported in previous studies, achieving precision and recall rates of 95.01% and 94.94% respectively, trained on a 237K-word training set.\",\n \"Title: Chinese word segmentation as LMR tagging\\nYear: 2003\\n\\nAbstract: In this paper we present Chinese word segmentation algorithms based on the so-called LMR tagging. Our LMR taggers are implemented with the Maximum Entropy Markov Model and we then use Transformation-Based Learning to combine the results of the two LMR taggers that scan the input in opposite directions. Our system achieves F-scores of 95.9% and 91.6% on the Academia Sinica corpus and the Hong Kong City University corpus respectively.\",\n \"Title: PropBank annotation of multilingual light verb constructions\\nYear: 2010\\n\\nAbstract: In this paper, we have addressed the task of PropBank annotation of light verb constructions, which like multi-word expressions pose special problems. To arrive at a solution, we have evaluated 3 different possible methods of annotation. The final method involves three passes: (1) manual identification of a light verb construction, (2) annotation based on the light verb construction's Frame File, and (3) a deterministic merging of the first two passes. We also discuss how in various languages the light verb constructions are identified and can be distinguished from the non-light verb word groupings.\",\n \"Title: Discourse-constrained temporal annotation\\nYear: 2011\\n\\nAbstract: We describe an experiment on a temporal ordering task in this paper. We show that by selecting event pairs based on discourse structure and by modifying the pre-existent temporal classification scheme to fit the data better, we significantly improve inter-annotator agreement, as well as broaden the coverage of the task. We also present analysis of the current temporal classification scheme and propose ways to improve it in future work.\",\n \"Title: OntoNotes: the 90% solution\\nYear: 2009\\n\\nAbstract: OntoNotes is a five year multi-site collaboration between BBN Technologies, Information Sciences Institute of University of Southern California, University of Colorado, University of Pennsylvania and Brandeis University. The goal of the OntoNotes project is to provide linguistic data annotated with a skeletal representation of the literal meaning of sentences including syntactic parse, predicate-argument structure, coreference, and word senses linked to an ontology, allowing a new generation of language understanding technologies to be developed with new functional capabilities.\",\n \"Title: Developing Guidelines and Ensuring Consistency for Chinese Text Annotation\\nYear: 2000\\n\\nAbstract: With growing interest in Chinese Language Processing, numerous NLP tools (e.g. word segmenters, part-of-speech taggers, and parsers)for Chinese have been developed all over the world. However, since no large-scale bracketed corpora are available to the public, thesetools are trained on the corpora with different segmentation criteria, part-of-speech tagsets and bracketing guidelines, and therefore,comparisons are difficult. As a first step towards addressing this issue, we have been...\",\n \"Title: A Machine Learning-Based Coreference Detection System for OntoNotes.\\nYear: 2011\\n\\nAbstract: In this paper, we describe the algorithms and experimental results of Brandeis University in the participation of the CoNLL Task 2011 closed track. We report the features used in our system, and describe a novel cluster-based chaining algorithm to improve performance of coreference identification. We evaluate the system using the OntoNotes data set and describe our results.\",\n \"Title: Annotating the propositions in the Penn Chinese Treebank\\nYear: 2003\\n\\nAbstract: In this paper, we describe an approach to annotate the propositions in the Penn Chinese Treebank. We describe how diathesis alternation patterns can be used to make coarse sense distinctions for Chinese verbs as a necessary step in annotating the predicate-structure of Chinese verbs. We then discuss the representation scheme we use to label the semantic arguments and adjuncts of the predicates. We discuss several complications for this type of annotation and describe our solutions. We then discuss how a lexical database with predicate-argument structure information can be used to ensure consistent annotation. Finally, we discuss possible applications for this resource.\",\n \"Title: The CoNLL-2009 shared task: syntactic and semantic dependencies in multiple languages\\nYear: 2009\\n\\nAbstract: For the 11th straight year, the Conference on Computational Natural Language Learning has been accompanied by a shared task whose purpose is to promote natural language processing applications and evaluate them in a standard setting. In 2009, the shared task was dedicated to the joint parsing of syntactic and semantic dependencies in multiple languages. This shared task combines the shared tasks of the previous five years under a unique dependency-based formalism similar to the 2008 task. In this paper, we define the shared task, describe how the data sets were created and show their quantitative properties, report the results and summarize the approaches of the participating systems.\",\n \"Title: Using parallel PropBanks to enhance word-alignments\\nYear: 2009\\n\\nAbstract: This short paper describes the use of the linguistic annotation available in parallel PropBanks (Chinese and English) for the enhancement of automatically derived word alignments. Specifically, we suggest ways to refine and expand word alignments for verb-predicates by using predicate-argument structures. Evaluations demonstrate improved alignment accuracies that vary by corpus type.\",\n \"Title: Aligning features with sense distinction dimensions\\nYear: 2006\\n\\nAbstract: In this paper we present word sense disambiguation (WSD) experiments on ten highly polysemous verbs in Chinese, where significant performance improvements are achieved using rich linguistic features. Our system performs significantly better, and in some cases substantially better, than the baseline on all ten verbs. Our results also demonstrate that features extracted from the output of an automatic Chinese semantic role labeling system in general benefited the WSD system, even though the amount of improvement was not consistent across the verbs. For a few verbs, semantic role information actually hurt WSD performance. The inconsistency of feature performance is a general characteristic of the WSD task, as has been observed by others. We argue that this result can be explained by the fact that word senses are partitioned along different dimensions for different verbs and the features therefore need to be tailored to particular verbs in order to achieve adequate accuracy on verb sense disambiguation.\",\n \"Title: Exploring temporal vagueness with mechanical turk\\nYear: 2012\\n\\nAbstract: This paper proposes schematic changes to the TempEval framework that target the temporal vagueness problem. Specifically, two elements of vagueness are singled out for special treatment: vague time expressions, and explicit/implicit temporal modification of events. As proof of concept, an annotation experiment on explicit/implicit modification is conducted on Amazon's Mechanical Turk. Results show that the quality of a considerable segment of the annotation is comparable to annotation obtained in the traditional double-blind setting, only with higher coverage. This approach offers additional flexibility in how the temporal annotation data can be used.\",\n \"Title: Automatic inference of the temporal location of situations in Chinese text\\nYear: 2008\\n\\nAbstract: Chinese is a language that does not have morphological tense markers that provide explicit grammaticalization of the temporal location of situations (events or states). However, in many NLP applications such as Machine Translation, Information Extraction and Question Answering, it is desirable to make the temporal location of the situations explicit. We describe a machine learning framework where different sources of information can be combined to predict the temporal location of situations in Chinese text. Our experiments show that this approach significantly outperforms the most frequent tense baseline. More importantly, the high training accuracy shows promise that this challenging problem is solvable to a level where it can be used in practical NLP applications with more training data, better modeling techniques and more informative and generalizable features.\",\n \"Title: Buy one get one free: Distant annotation of Chinese tense, event type and modality.\\nYear: 2014\\n\\nAbstract: We describe a \\\"distant annotation\\\" method where we mark up the semantic tense, event type, and modality of Chinese events via a word-aligned parallel corpus. We first map Chinese verbs to their English counterparts via word alignment, and then annotate the resulting English text spans with coarse-grained categories for semantic tense, event type, and modality that we believe apply to both English and Chinese. Because English has richer morpho-syntactic indicators for semantic tense, event type and modality than Chinese, our intuition is that this distant annotation approach will yield more consistent annotation than if we annotate the Chinese side directly. We report experimental results that show stable annotation agreement statistics and that event type and modality have significant influence on tense prediction. We also report the size of the annotated corpus that we have obtained, and how different domains impact annotation consistency.\",\n \"Title: Chinese sentence segmentation as comma classification\\nYear: 2011\\n\\nAbstract: We describe a method for disambiguating Chinese commas that is central to Chinese sentence segmentation. Chinese sentence segmentation is viewed as the detection of loosely coordinated clauses separated by commas. Trained and tested on data derived from the Chinese Treebank, our model achieves a classification accuracy of close to 90% overall, which translates to an F1 score of 70% for detecting commas that signal sentence boundaries.\",\n \"Title: Annotating the Predicate-Argument Structure of Chinese Nominalizations\\nYear: 2006\\n\\nAbstract: Abstract This paper describes the Chinese NomBank Project, the goal of which is to annotate the predicate-argument structure of nominalized predicates in Chinese. The Chinese Nombank,extends the general framework,of the English and Chinese Proposition Banks to the annotation of nominalized,predicates and adds a layer of semantic annotation to the Chinese Treebank. We first outline the scope of the work by discussing the markability of the nominalized,predicates and their arguments. We then attempt to provide a categorization of the distribution of the arguments,of nominalized predicates. We also discuss the relevance of the event/result distinction to the annotation of nominalized,predicates and the phenomenon,of incorporation. Finally we discuss some cross-linguistic differences between,English and Chinese.\",\n \"Title: Calibrating Features for Semantic Role Labeling\\nYear: 2004\\n\\nAbstract: This paper takes a critical look at the features used in the semantic role tagging literature and show that the information in the input, gener- ally a syntactic parse tree, has yet to be fully exploited. We propose an additional set of fea- tures and our experiments show that these fea- tures lead to fairly signicant improvements in the tasks we performed. We further show that dierent features are needed for dierent sub- tasks. Finally, we show that by using a Maxi- mum Entropy classier and fewer features, we achieved results comparable with the best previ- ously reported results obtained with SVM mod- els. We believe this is a clear indication that developing features that capture the right kind of information is crucial to advancing the state- of-the-art in semantic analysis.\",\n \"Title: Automatic semantic role labeling for Chinese verbs\\nYear: 2005\\n\\nAbstract: Recent years have seen a revived interest in semantic parsing by applying statistical and machine-learning methods to semantically annotated corpora such as the FrameNet and the Proposition Bank. So far much of the research has been focused on English due to the lack of semantically annotated resources in other languages. In this paper, we report first results on semantic role labeling using a pre-release version of the Chinese Proposition Bank. Since the Chinese Proposition Bank is superimposed on top of the Chinese Tree-bank, i.e., the semantic role labels are assigned to constituents in a treebank parse tree, we start by reporting results on experiments using the handcrafted parses in the treebank. This will give us a measure of the extent to which the semantic role labels can be bootstrapped from the syntactic annotation in the treebank. We will then report experiments using a fully automatic Chinese parser that integrates word segmentation, POS-tagging and parsing. This will gauge how successful semantic role labeling can be done for Chinese in realistic situations. We show that our results using hand-crafted parses are slightly higher than the results reported for the state-of-the-art semantic role labeling systems for English using the Penn English Proposition Bank data, even though the Chinese Proposition Bank is smaller in size. When an automatic parser is used, however, the accuracy of our system is much lower than the English state-of-the-art. This reveals an interesting cross-linguistic difference between the two languages, which we attempt to explain. We also describe a method to induce verb classes from the Proposition Bank \\\"frame files\\\" that can be used to improve semantic role labeling.\",\n \"Title: Adding semantic roles to the chinese treebank\\nYear: 2009\\n\\nAbstract: We report work on adding semantic role labels to the Chinese Treebank, a corpus already annotated with phrase structures. The work involves locating all verbs and their nominalizations in the corpus, and semi-automatically adding semantic role labels to their arguments, which are constituents in a parse tree. Although the same procedure is followed, different issues arise in the annotation of verbs and nominalized predicates. For verbs, identifying their arguments is generally straightforward given their syntactic structure in the Chinese Treebank as they tend to occupy well-defined syntactic positions. Our discussion focuses on the syntactic variations in the realization of the arguments as well as our approach to annotating dislocated and discontinuous arguments. In comparison, identifying the arguments for nominalized predicates is more challenging and we discuss criteria and procedures for distinguishing arguments from non-arguments. In particular we focus on the role of support verbs as well as the relevance of event/result distinctions in the annotation of the predicate-argument structure of nominalized predicates. We also present our approach to taking advantage of the syntactic structure in the Chinese Treebank to bootstrap the predicate-argument structure annotation of verbs. Finally, we discuss the creation of a lexical database of frame files and its role in guiding predicate-argument annotation. Procedures for ensuring annotation consistency and inter-annotator agreement evaluation results are also presented.\",\n \"Title: Combining classifiers for Chinese word segmentation\\nYear: 2002\\n\\nAbstract: In this paper we report results of a supervised machine-learning approach to Chinese word segmentation. First, a maximum entropy tagger is trained on manually annotated data to automatically labels the characters with tags that indicate the position of character within a word. An error-driven transformation-based tagger is then trained to clean up the tagging inconsistencies of the first tagger. The tagged output is then converted into segmented text. The preliminary results show that this approach is competitive compared with other supervised machine-learning segmenters reported in previous studies.\",\n \"Title: Chinese comma disambiguation for discourse analysis\\nYear: 2012\\n\\nAbstract: The Chinese comma signals the boundary of discourse units and also anchors discourse relations between adjacent text spans. In this work, we propose a discourse structure-oriented classification of the comma that can be automatically extracted from the Chinese Treebank based on syntactic patterns. We then experimented with two supervised learning methods that automatically disambiguate the Chinese comma based on this classification. The first method integrates comma classification into parsing, and the second method adopts a \\\"post-processing\\\" approach that extracts features from automatic parses to train a classifier. The experimental results show that the second approach compares favorably against the first approach.\",\n \"Title: Automatic recognition of logical relations for English, Chinese and Japanese in the GLARF framework\\nYear: 2009\\n\\nAbstract: We present GLARF, a framework for representing three linguistic levels and systems for generating this representation. We focus on a logical level, like LFG's F-structure, but compatible with Penn Treebanks. While less finegrained than typical semantic role labeling approaches, our logical structure has several advantages: (1) it includes all words in all sentences, regardless of part of speech or semantic domain; and (2) it is easier to produce accurately. Our systems achieve 90% for English/Japanese News and 74.5% for Chinese News -- these F-scores are nearly the same as those achieved for treebank-based parsing.\",\n \"Title: Annotating discourse connectives in the Chinese Treebank\\nYear: 2005\\n\\nAbstract: In this paper we examine the issues that arise from the annotation of the discourse connectives for the Chinese Discourse Treebank Project. This project is based on the same principles as the PDTB, a project that annotates the English discourse connectives in the Perm Treebank. The paper begins by outlining range of discourse connectives under consideration in this project and examines the distribution of the explicit discourse connectives. We then examine the types of syntactic units that can be arguments to the discourse connectives. We show that one of the most challenging issues in this type of discourse annotation is determining the textual spans of the arguments and this is partly due to the hierarchical nature of discourse relations. Finally, we discuss sense discrimination of the discourse connectives, which involves separating discourse connective from non-discourse connective senses and teasing apart the different discourse connective senses, and discourse connective variation, the use of different connectives to represent the same discourse relation.\",\n \"Title: A parallel Proposition Bank II for Chinese and English\\nYear: 2005\\n\\nAbstract: The Proposition Bank (PropBank) project is aimed at creating a corpus of text annotated with information about semantic propositions. The second phase of the project, PropBank II adds additional levels of semantic annotation which include eventuality variables, co-reference, coarse-grained sense tags, and discourse connectives. This paper presents the results of the parallel PropBank II project, which adds these richer layers of semantic annotation to the first 100K of the Chinese Treebank and its English translation. Our preliminary analysis supports the hypothesis that this additional annotation reconciles many of the surface differences between the two languages.\",\n \"Title: Transducing logical relations from automatic and manual GLARF\\nYear: 2009\\n\\nAbstract: GLARF relations are generated from treebank and parses for English, Chinese and Japanese. Our evaluation of system output for these input types requires consideration of multiple correct answers.\",\n \"Title: PDTB-style discourse annotation of Chinese text\\nYear: 2012\\n\\nAbstract: We describe a discourse annotation scheme for Chinese and report on the preliminary results. Our scheme, inspired by the Penn Discourse TreeBank (PDTB), adopts the lexically grounded approach; at the same time, it makes adaptations based on the linguistic and statistical characteristics of Chinese text. Annotation results show that these adaptations work well in practice. Our scheme, taken together with other PDTB-style schemes (e.g. for English, Turkish, Hindi, and Czech), affords a broader perspective on how the generalized lexically grounded approach can flesh itself out in the context of cross-linguistic annotation of discourse relations.\",\n \"Title: Using a smoothing maximum entropy model for chinese nominal entity tagging\\nYear: 2004\\n\\nAbstract: This paper treats nominal entity tagging as a six-way (five categories plus non-entity) classification problem and applies a smoothing maximum entropy (ME) model with a Gaussian prior to a Chinese nominal entity tagging task. The experimental results show that the model performs consistently better than an ME model using a simple count cut-off. The results also suggest that simple semantic features extracted from an electronic dictionary improve the model’s performance, especially when the training data is insufficient.\",\n \"Title: Chasing the ghost: recovering empty categories in the Chinese treebank\\nYear: 2010\\n\\nAbstract: Empty categories represent an important source of information in syntactic parses annotated in the generative linguistic tradition, but empty category recovery has only started to receive serious attention until very recently, after substantial progress in statistical parsing. This paper describes a unified framework in recovering empty categories in the Chinese Tree-bank. Our results show that given skeletal gold standard parses, the empty categories can be detected with very high accuracy. We report very promising results for empty category recovery for automatic parses as well.\",\n \"Title: Semantic role labeling of nominalized predicates in Chinese\\nYear: 2006\\n\\nAbstract: Recent work on semantic role labeling (SRL) has focused almost exclusively on the analysis of the predicate-argument structure of verbs, largely due to the lack of human-annotated resources for other types of predicates that can serve as training and test data for the semantic role labeling systems. However, it is well-known that verbs are not the only type of predicates that can take arguments. Most notably, nouns that are nominalized forms of verbs and relational nouns generally are also considered to have their own predicate-argument structure. In this paper we report results of SRL experiments on nominalized predicates in Chinese, using a newly completed corpus, the Chinese Nombank. We also discuss the impact of using publicly available manually annotated verb data to improve the SRL accuracy of nouns, exploiting a widely-held assumption that verbs and their nominalizations share the same predicate-argument structure. Finally, we discuss the results of applying reranking techniques to improve SRL accuracy for nominalized predicates, which showed insignificant improvement.\",\n \"Title: Proposition Bank II: Delving Deeper\\nYear: 2004\\n\\nAbstract: The PropBank project is creating a corpus of text annotated with information about basic semantic propositions. PropBank I (Kingsbury & Palmer, 2002) added a layer of predicate- argument information, or semantic roles, to the syntactic structures of the English Penn Treebank. This paper presents an overview of the second phase of PropBank Annotation, PropBank II, which is being applied to Eng- lish and Chinese, and includes (Neodavid- sonian) eventuality variables, nominal references, sense tagging, and connections to the Penn Discourse Treebank (PDTB), a pro- ject for annotating discourse connectives and their arguments.\",\n \"Title: Bidirectional Sequence Labeling Via Dual Decomposition\\nYear: 2013\\n\\nAbstract: In this paper, we propose a bidirectional algorithm for sequence labeling to capture the influence of both the left-to-right and the right-to-left directions. We combine the optimization of two unidirectional models from opposite directions via the dual decomposition method to jointly label the input sequence. Experiments on three sequence labeling tasks (Chinese word segmentation, English POS tagging and text chunking) show that our approach can improve the accuracy of sequence labeling tasks when the two unidirectional models individually make highly different predictions.\",\n \"Title: Improving MT word alignment using aligned multi-stage parses\\nYear: 2011\\n\\nAbstract: We use hand-coded rules and graph-aligned logical dependencies to reorder English text towards Chinese word order. We obtain a 1.5% higher F-score for Giza++ compared to running with unprocessed text. We describe this research and its implications for SMT.\",\n \"Title: Not an Interlingua, But Close: Comparison of English AMRs to Chinese and Czech.\\nYear: 2014\\n\\nAbstract: Meaning Representations (AMRs) are rooted, directional and labeled graphs that abstract away from morpho-syntactic idiosyncrasies such as word category (verbs and nouns), word order, and function words (determiners, some prepositions). Because these syntactic idiosyncrasies account for many of the cross-lingual differences, it would be interesting to see if this representation can serve, e.g., as a useful, minimally divergent transfer layer in machine translation. To answer this question, we have translated 100 English sentences that have existing AMRs into Chinese and Czech to create AMRs for them. A cross-linguistic comparison of English to Chinese and Czech AMRs reveals both cases where the AMRs for the language pairs align well structurally and cases of linguistic divergence. We found that the level of compatibility of AMR between English and Chinese is higher than between English and Czech. We believe this kind of comparison is beneficial to further refining the annotation standards for each of the three languages and will lead to more compatible annotation guidelines between the languages.\",\n \"Title: Annotating dropped pronouns in Chinese newswire text.\\nYear: 2012\\n\\nAbstract: We propose an annotation framework to explicitly identify dropped subject pronouns in Chinese. We acknowledge and specify 10 concrete pronouns that exist as words in Chinese and 4 abstract pronouns that do not correspond to Chinese words, but that are recognized conceptually, to native Chinese speakers. These abstract pronouns are identified as \\\"unspecified\\\", \\\"pleonastic\\\", \\\"event\\\", and \\\"existential\\\" and are argued to exist cross-linguistically. We trained two annotators, fluent in Chinese, and adjudicated their annotations to form a gold standard. We achieved an inter-annotator agreement kappa of .6 and an observed agreement of .7. We found that annotators had the most difficulty with the abstract pronouns, such as \\\"unspecified\\\" and \\\"event\\\", but we posit that further specification and training has the potential to significantly improve these results. We believe that this annotated data will serve to help improve Machine Translation models that translate from Chinese to a non pro-drop language, like English, that requires all subject pronouns to be explicit.\",\n \"Title: Parallel Aligned Treebanks at LDC: New Challenges Interfacing Existing Infrastructures.\\nYear: 2012\\n\\nAbstract: Parallel aligned treebanks (PAT) are linguistic corpora annotated with morphological and syntactic structures that are aligned at sentence as well as sub-sentence levels. They are valuable resources for improving machine translation (MT) quality. Recently, there has been an increasing demand for such data, especially for divergent language pairs. The Linguistic Data Consortium (LDC) and its academic partners have been developing Arabic-English and Chinese-English PATs for several years. This paper describes the PAT corpus creation effort for the program GALE (Global Autonomous Language Exploitation) and introduces the potential issues of scaling up this PAT effort for the program BOLT (Broad Operational Language Translation). Based on existing infrastructures and in the light of current annotation process, challenges and approaches, we are exploring new methodologies to address emerging challenges in constructing PATs, including data volume bottlenecks, dialect issues of Arabic languages, and new genre features related to rapidly changing social media. Preliminary experimental results are presented to show the feasibility of the approaches proposed.\",\n \"Title: A corpus of full-text journal articles is a robust evaluation tool for revealing differences in performance of biomedical natural language processing tools.\\nYear: 2012\\n\\nAbstract: We introduce the linguistic annotation of a corpus of 97 full-text biomedical publications, known as the Colorado Richly Annotated Full Text (CRAFT) corpus. We further assess the performance of existing tools for performing sentence splitting, tokenization, syntactic parsing, and named entity recognition on this corpus.Many biomedical natural language processing systems demonstrated large differences between their previously published results and their performance on the CRAFT corpus when tested with the publicly available models or rule sets. Trainable systems differed widely with respect to their ability to build high-performing models based on this data.The finding that some systems were able to train high-performing models based on this corpus is additional evidence, beyond high inter-annotator agreement, that the quality of the CRAFT corpus is high. The overall poor performance of various systems indicates that considerable work needs to be done to enable natural language processing systems to work well when the input is full-text journal articles. The CRAFT corpus provides a valuable resource to the biomedical natural language processing community for evaluation and training of new models for biomedical full text publications.\",\n \"Title: Automatic predicate argument structure analysis of the Penn Chinese Treebank.\\nYear: 2003\\n\\nAbstract: Recent work in machine translation and information extraction has demonstrated the utility of a level that represents the predicate-argument structure. It would be especially useful for machine translation to have two such Proposition Banks, one for each language under consideration. A Proposition Bank for English has been developed over the last few years, and we describe here our development of a tool for facilitating the development of a Chinese Proposition Bank. We also discuss some issues specific to the Chinese Treebank that complicate the matter of mapping syntactic representation to a predicate-argument level, and report on some preliminary evaluation of the accuracy of the semantic tagging tool.\",\n \"Title: Temporal relation discovery between events and temporal expressions identified in clinical narrative.\\nYear: 2013\\n\\nAbstract: The automatic detection of temporal relations between events in electronic medical records has the potential to greatly augment the value of such records for understanding disease progression and patients' responses to treatments. We present a three-step methodology for labeling temporal relations using machine learning and deterministic rules over an annotated corpus provided by the 2012 i2b2 Shared Challenge. We first create an expanded training network of relations by computing the transitive closure over the annotated data; we then apply hand-written rules and machine learning with a feature set that casts a wide net across potentially relevant lexical and syntactic information; finally, we employ a voting mechanism to resolve global contradictions between the local predictions made by the learned classifier. Results over the testing data illustrate the contributions of initial prediction and conflict resolution.\",\n \"Title: A Chinese semantic lexicon of senses and roles\\nYear: 2006\\n\\nAbstract: We describe a Chinese lexical semantic resource that consists of 11,765 predicates (mostly verbs and their nominalizations)\\n analyzed with coarse-grained senses and semantic roles. We show that distinguishing senses at a coarse-grained level is a\\n necessary part of specifying the semantic roles and describe our strategies for sense determination for purposes of predicate-argument\\n structure specification. The semantic roles are postulated to account for syntactic variations, the different ways in which\\n the semantic roles of a predicate are realized. The immediate purpose for this lexical semantic resource is to support the\\n annotation of the Chinese PropBank, but we believe it can also serve as stepping stone for higher-level semantic generalizations.\",\n \"Title: Labeling chinese predicates with semantic roles\\nYear: 2008\\n\\nAbstract: In this article we report work on Chinese semantic role labeling, taking advantage of two recently completed corpora, the Chinese PropBank, a semantically annotated corpus of Chinese verbs, and the Chinese Nombank, a companion corpus that annotates the predicate-argument structure of nominalized predicates. Because the semantic role labels are assigned to the constituents in a parse tree, we first report experiments in which semantic role labels are automatically assigned to hand-crafted parses in the Chinese Treebank. This gives us a measure of the extent to which semantic role labels can be bootstrapped from the syntactic annotation provided in the treebank. We then report experiments using automatic parses with decreasing levels of human annotation in the input to the syntactic parser: parses that use gold-standard segmentation and POS-tagging, parses that use only gold-standard segmentation, and fully automatic parses. These experiments gauge how successful semantic role labeling for Chinese can be in more realistic situations. Our results show that when hand-crafted parses are used, semantic role labeling accuracy for Chinese is comparable to what has been reported for the state-of-the-art English semantic role labeling systems trained and tested on the English PropBank, even though the Chinese PropBank is significantly smaller in size. When an automatic parser is used, however, the accuracy of our system is significantly lower than the English state of the art. This indicates that an improvement in Chinese parsing is critical to high-performance semantic role labeling for Chinese.\",\n \"Title: CoNLL-2011 Shared Task: Modeling Unrestricted Coreference in OntoNotes.\\nYear: 2011\\n\\nAbstract: The CoNLL-2011 shared task involved predicting coreference using OntoNotes data. Resources in this field have tended to be limited to noun phrase coreference, often on a restricted set of entities, such as ace entities. OntoNotes provides a large-scale corpus of general anaphoric coreference not restricted to noun phrases or to a specified set of entity types. OntoNotes also provides additional layers of integrated annotation, capturing additional shallow semantic structure. This paper briefly describes the OntoNotes annotation (coreference and other layers) and then describes the parameters of the shared task including the format, pre-processing information, and evaluation criteria, and presents and discusses the results achieved by the participating systems. Having a standard test set and evaluation parameters, all based on a new resource that provides multiple integrated annotation layers (parses, semantic roles, word senses, named entities and coreference) that could support joint models, should help to energize ongoing research in the task of entity and event coreference.\",\n \"Title: Annotating \\\"tense\\\" in a Tense-less Language\\nYear: 2008\\n\\nAbstract: In the context of Natural Language Processing, annotation is about recovering implicit information that is useful for natural language applications. In this paper we describe a \\\"tense\\\" annotation task for Chinese, a language that does not have grammatical tense, that is designed to infer the temporal location of a situation in relation to the temporal deixis, the moment of speech. If successful, this would be a highly rewarding endeavor as it has application in many natural language systems. Our preliminary experiments show that while this is a very challenging annotation task for which high annotation consistency is very difficult but not impossible to achieve. We show that guidelines that provide a conceptually intuitive framework will be crucial to the success of this annotation effort.\",\n \"Title: The Chinese Discourse TreeBank: a Chinese corpus annotated with discourse relations\\nYear: 2015\\n\\nAbstract: The paper presents the Chinese Discourse TreeBank, a corpus annotated with Penn Discourse TreeBank style discourse relations that take the form of a predicate taking two arguments. We first characterize the syntactic and statistical distributions of Chinese discourse connectives as well as the role of Chinese punctuation marks in discourse annotation, and then describe how we design our annotation strategy procedure based on this characterization. The Chinese-specific features of our annotation strategy include annotating explicit and implicit discourse relations in one single pass, defining the argument labels on semantic, rather than syntactic, grounds, as well as annotating the semantic type of implicit discourse relations directly. We also introduce a flat, 11-valued semantic type classification scheme for discourse relations. We finally demonstrate the feasibility of our approach with evaluation results.\",\n \"Title: Effective Document-Level Features For Chinese Patent Word Segmentation\\nYear: 2014\\n\\nAbstract: A patent is a property right for an invention granted by the government to the inventor. Patents often have a high concentration of scientific and technical terms that are rare in everyday language. However, some scientific and technical terms usually appear with high frequency only in one specific patent. In this paper, we propose a pragmatic approach to Chinese word segmentation on patents where we train a sequence labeling model based on a group of novel document-level features. Experiments show that the accuracy of our model reached 96.3% (F-1 score) on the development set and 95.0% on a held-out test set.\",\n \"Title: Feature Optimization For Constituent Parsing Via Neural Networks\\nYear: 2015\\n\\nAbstract: The performance of discriminative constituent parsing relies crucially on feature engineering, and effective features usually have to be carefully selected through a painful manual process. In this paper, we propose to automatically learn a set of effective features via neural networks. Specifically, we build a feedforward neural network model, which takes as input a few primitive units (words, POS tags and certain contextual tokens) from the local context, induces the feature representation in the hidden layer and makes parsing predictions in the output layer. The network simultaneously learns the feature representation and the prediction model parameters using a back propagation algorithm. By pre-training the model on a large amount of automatically parsed data, and then fine-tuning on the manually annotated Treebank data, our parser achieves the highest F-1 score at 86.6% on Chinese Treebank 5.1, and a competitive F-1 score at 90.7% on English Treebank. More importantly, our parser generalizes well on cross-domain test sets, where we significantly outperform Berkeley parser by 3.4 points on average for Chinese and 2.5 points for English.\",\n \"Title: Recovering Dropped Pronouns From Chinese Text Messages\\nYear: 2015\\n\\nAbstract: Pronouns are frequently dropped in Chinese sentences, especially in informal data such as text messages. In this work we propose a solution to recover dropped pronouns in SMS data. We manually annotate dropped pronouns in 684 SMS files and apply machine learning algorithms to recover them, leveraging lexical, contextual and syntactic information as features. We believe this is the first work on recovering dropped pronouns in Chinese text messages.\",\n \"Title: Boosting Transition-Based Amr Parsing With Refined Actions And Auxiliary Analyzers\\nYear: 2015\\n\\nAbstract: We report improved AMR parsing results by adding a new action to a transition-based AMR parser to infer abstract concepts and by incorporating richer features produced by auxiliary analyzers such as a semantic role labeler and a coreference resolver. We report final AMR parsing results that show an improvement of 7% absolute in F-1 score over the best previously reported result. Our parser is available at: https://github.com/Juicechuan/AMRParsing\",\n \"Title: A Transition-based Algorithm for AMR Parsing.\\nYear: 2015\\n\\nAbstract: We present a two-stage framework to parse a sentence into its Abstract Meaning Representation (AMR). We first use a dependency parser to generate a dependency tree for the sentence. In the second stage, we design a novel transition-based algorithm that transforms the dependency tree to an AMR graph. There are several advantages with this approach. First, the dependency parser can be trained on a training set much larger than the training set for the tree-to-graph algorithm, resulting in a more accurate AMR parser overall. Our parser yields an improvement of 5% absolute in F-measure over the best previous result. Second, the actions that we design are linguistically intuitive and capture the regularities in the mapping between the dependency structure and the AMR of a sentence. Third, our parser runs in nearly linear time in practice in spite of a worst-case complexity ofO(n 2 ).\",\n \"Title: Improving the Inference of Implicit Discourse Relations via Classifying Explicit Discourse Connectives.\\nYear: 2015\\n\\nAbstract: Discourse relation classification is an important component for automatic discourse parsing and natural language understanding. The performance bottleneck of a discourse parser comes from implicit discourse relations, whose discourse connectives are not overtly present. Explicit discourse connectives can potentially be exploited to collect more training data to collect more data and boost the performance. However, using them indiscriminately has been shown to hurt the performance because not all discourse connectives can be dropped arbitrarily. Based on this insight, we investigate the interaction between discourse connectives and the discourse relations and propose the criteria for selecting the discourse connectives that can be dropped independently of the context without changing the interpretation of the discourse. Extra training data collected only by the freely omissible connectives improve the performance of the system without additional features.\",\n \"Title: Neural Network Models for Implicit Discourse Relation Classification in English and Chinese without Surface Features.\\nYear: 2016\\n\\nAbstract: Inferring implicit discourse relations in natural language text is the most difficult subtask in discourse parsing. Surface features achieve good performance, but they are not readily applicable to other languages without semantic lexicons. Previous neural models require parses, surface features, or a small label set to work well. Here, we propose neural network models that are based on feedforward and long-short term memory architecture without any surface features. To our surprise, our best configured feedforward architecture outperforms LSTM-based model in most cases despite thorough tuning. Under various fine-grained label sets and a cross-linguistic setting, our feedforward models perform consistently better or at least just as well as systems that require hand-crafted surface features. Our models present the first neural Chinese discourse parser in the style of Chinese Discourse Treebank, showing that our results hold cross-linguistically.\",\n \"Title: Large Multi-lingual, Multi-level and Multi-genre Annotation Corpus.\\nYear: 2016\\n\\nAbstract: High accuracy for automated translation and information retrieval calls for linguistic annotations at various language levels. The plethora of informal internet content sparked the demand for porting state-of-art natural language processing (NLP) applications to new social media as well as diverse language adaptation. Effort launched by the BOLT (Broad Operational Language Translation) program at DARPA (Defense Advanced Research Projects Agency) successfully addressed the internet information with enhanced NLP systems. BOLT aims for automated translation and linguistic analysis for informal genres of text and speech in online and in-person communication. As a part of this program, the Linguistic Data Consortium (LDC) developed valuable linguistic resources in support of the training and evaluation of such new technologies. This paper focuses on methodologies, infrastructure, and procedure for developing linguistic annotation at various language levels, including Treebank (TB), word alignment (WA), PropBank (PB), and co-reference (CoRef). Inspired by the OntoNotes approach with adaptations to the tasks to reflect the goals and scope of the BOLT project, this effort has introduced more annotation types of informal and free-style genres in English, Chinese and Egyptian Arabic. The corpus produced is by far the largest multi-lingual, multi-level and multi-genre annotation corpus of informal text and speech.\",\n \"Title: Generalizing the semantic roles in the Chinese Proposition Bank.\\nYear: 2016\\n\\nAbstract: The Chinese Proposition Bank (CPB) is a corpus annotated with semantic roles for the arguments of verbal and nominalized predicates. The semantic roles for the core arguments are defined in a predicate-specific manner. That is, a set of semantic roles, numerically identified, are defined for each sense of a predicate lemma and recorded in a valency lexicon called frame files. The predicate-specific manner in which the semantic roles are defined reduces the cognitive burden on the annotators since they only need to internalize a few roles at a time and this has contributed to the consistency in annotation. It was also a sensible approach given the contentious issue of how many semantic roles are needed if one were to adopt of set of global semantic roles that apply to all predicates. A downside of this approach, however, is that the predicate-specific roles may not be consistent across predicates, and this inconsistency has a negative impact on training automatic systems. Given the progress that has been made in defining semantic roles in the last decade or so, time is ripe for adopting a set of general semantic roles. In this article, we describe our effort to \\\\\\\"re-annotate\\\\\\\" the CPB with a set of \\\\\\\"global\\\\\\\" semantic roles that are predicate-independent and investigate their impact on automatic semantic role labeling systems. When defining these global semantic roles, we strive to make them compatible with a recently published ISO standards on the annotation of semantic roles (ISO 24617-4:2014 SemAF-SR) while taking the linguistic characteristics of the Chinese language into account. We show that in spite of the much larger number of global semantic roles, the accuracy of an off-the-shelf semantic role labeling system retrained on the data re-annotated with global semantic roles is comparable to that trained on the data set with the original predicate-specific semantic roles. We also argue that the re-annotated data set, together with the original data, provides the user with more flexibility when using the corpus.\",\n \"Title: CoNLL 2016 Shared Task on Multilingual Shallow Discourse Parsing.\\nYear: 2016\\n\\nAbstract: The CoNLL-2016 Shared Task is the second edition of the CoNLL-2015 Shared Task, now on Multilingual Shallow discourse parsing. Similar to the 2015 task, the goal of the shared task is to identify individual discourse relations that are present in natural language text. Given a natural language text, participating teams are asked to locate the discourse connectives (explicit or implicit) and their arguments as well as predicting the sense of the discourse connectives. Based on the success of the previous year, we continued to ask participants to deploy their systems on TIRA, a web-based platform on which participants can run their systems on the test data for evaluation. This evaluation methodology preserves the integrity of the shared task. We have also made a few changes and additions in the 2016 shared task based on the feedback from 2015. The first is that teams could choose to carry out the task on Chinese texts, or English texts, or both. We have also allowed participants to focus on parts of the shared task (rather than the whole thing) as a typical system requires substantial investment of effort. Finally, we have modified the scorer so that it can report results based on partial matches of the arguments. 23 teams participated in this year’s shared task, using a wide variety of approaches. In this overview paper, we present the task definition, the training and test sets, and the evaluation protocol and metric used during this shared task. We also summarize the different approaches adopted by the participating teams, and present the evaluation results. The evaluation data sets and the scorer will serve as a benchmark for future research on shallow discourse parsing.\",\n \"Title: Towards Accurate Word Segmentation for Chinese Patents.\\nYear: 2016\\n\\nAbstract: A patent is a property right for an invention granted by the government to the inventor. An invention is a solution to a specific technological problem. So patents often have a high concentration of scientific and technical terms that are rare in everyday language. The Chinese word segmentation model trained on currently available everyday language data sets performs poorly because it cannot effectively recognize these scientific and technical terms. In this paper we describe a pragmatic approach to Chinese word segmentation on patents where we train a character-based semi-supervised sequence labeling model by extracting features from a manually segmented corpus of 142 patents, enhanced with information extracted from the Chinese TreeBank. Experiments show that the accuracy of our model reached 95.08% (F1 score) on a held-out test set and 96.59% on development set, compared with an F1 score of 91.48% on development set if the model is trained on the Chinese TreeBank. We also experimented with some existing domain adaptation techniques, the results show that the amount of target domain data and the selected features impact the performance of the domain adaptation techniques.\",\n \"Title: Addressing the Data Sparsity Issue in Neural AMR Parsing.\\nYear: 2017\\n\\nAbstract: Neural attention models have achieved great success in different NLP tasks. How- ever, they have not fulfilled their promise on the AMR parsing task due to the data sparsity issue. In this paper, we de- scribe a sequence-to-sequence model for AMR parsing and present different ways to tackle the data sparsity problem. We show that our methods achieve significant improvement over a baseline neural atten- tion model and our results are also compet- itive against state-of-the-art systems that do not use extra linguistic resources.\",\n \"Title: Translation Divergences in Chinese-English Machine Translation: An Empirical Investigation.\\nYear: 2017\\n\\nAbstract: In this article, we conduct an empirical investigation of translation divergences between Chinese and English relying on a parallel treebank. To do this, we first devise a hierarchical alignment scheme where Chinese and English parse trees are aligned in a way that eliminates conflicts and redundancies between word alignments and syntactic parses to prevent the generation of spurious translation divergences. Using this Hierarchically Aligned Chinese-English Parallel Treebank HACEPT, we are able to semi-automatically identify and categorize the translation divergences between the two languages and quantify each type of translation divergence. Our results show that the translation divergences are much broader than described in previous studies that are largely based on anecdotal evidence and linguistic knowledge. The distribution of the translation divergences also shows that some high-profile translation divergences that motivate previous research are actually very rare in our data, whereas other translation divergences that have previously received little attention actually exist in large quantities. We also show that HACEPT allows the extraction of syntax-based translation rules, most of which are expressive enough to capture the translation divergences, and point out that the syntactic annotation in existing treebanks is not optimal for extracting such translation rules. We also discuss the implications of our study for attempts to bridge translation divergences by devising shared semantic representations across languages. Our quantitative results lend further support to the observation that although it is possible to bridge some translation divergences with semantic representations, other translation divergences are open-ended, thus building a semantic representation that captures all possible translation divergences may be impractical.\",\n \"Title: Structured Interpretation of Temporal Relations.\\nYear: 2018\\n\\nAbstract: Temporal relations between events and time expressions in a document are often modeled in an unstructured manner where relations between individual pairs of time expressions and events are considered in isolation. This often results in inconsistent and incomplete annotation and computational modeling. We propose a novel annotation approach where events and time expressions in a document form a dependency tree in which each dependency relation corresponds to an instance of temporal anaphora where the antecedent is the parent and the anaphor is the child. We annotate a corpus of 235 documents using this approach in the two genres of news and narratives, with 48 documents doubly annotated. We report a stable and high inter-annotator agreement on the doubly annotated subset, validating our approach, and perform a quantitative comparison between the two genres of the entire corpus. We make this corpus publicly available.\",\n \"Title: Neural Ranking Models for Temporal Dependency Structure Parsing.\\nYear: 2018\\n\\nAbstract: We design and build the first neural temporal dependency parser. It utilizes a neural ranking model with minimal feature engineering, and parses time expressions and events in a text into a temporal dependency tree structure. We evaluate our parser on two domains: news reports and narrative stories. In a parsing-only evaluation setup where gold time expressions and events are provided, our parser reaches 0.81 and 0.70 f-score on unlabeled and labeled parsing respectively, a result that is very competitive against alternative approaches. In an end-to-end evaluation setup where time expressions and events are automatically recognized, our parser beats two strong baselines on both data domains. Our experimental results and discussions shed light on the nature of temporal dependency structures in different domains and provide insights that we believe will be valuable to future research in this area.\",\n \"Title: A Survey of Discourse Representations for Chinese Discourse Annotation\\nYear: 2019\\n\\nAbstract: A key element in computational discourse analysis is the design of a formal representation for the discourse structure of a text. With machine learning being the dominant method, it is important to identify a discourse representation that can be used to perform large-scale annotation. This survey provides a systematic analysis of existing discourse representation theories to evaluate whether they are suitable for annotation of Chinese text. Specifically, the two properties, expressiveness and practicality, are introduced to compare the representations of theories based on rhetorical relations and the representations of theories based on entity relations. The comparison systematically reveals linguistic and computational characteristics of the theories. After that, we conclude that none of the existing theories are quite suitable for scalable Chinese discourse annotation because they are not both expressive and practical. Therefore, a new discourse representation needs to be proposed, which should balance the expressiveness and practicality, and cover rhetorical relations and entity relations. Inspired by the conclusions, this survey discusses some preliminary proposals on how to represent the discourse structure that are worth pursuing.\",\n \"Title: Recovering Dropped Pronouns in Chinese Conversations via Modeling Their Referents.\\nYear: 2019\\n\\nAbstract: Pronouns are often dropped in Chinese sentences, and this happens more frequently in conversational genres as their referents can be easily understood from context. Recovering dropped pronouns is essential to applications such as Information Extraction where the referents of these dropped pronouns need to be resolved, or Machine Translation when Chinese is the source language. In this work, we present a novel end-to-end neural network model to recover dropped pronouns in conversational data. Our model is based on a structured attention mechanism that models the referents of dropped pronouns utilizing both sentence-level and word-level information. Results on three different conversational genres show that our approach achieves a significant improvement over the current state of the art.\",\n \"Title: UMR-Writer: A Web Application for Annotating Uniform Meaning Representations\\nYear: 2021\\n\\nAbstract: We present UMR-Writer, a web-based application for annotating Uniform Meaning Representations (UMR), a graph-based, cross-linguistically applicable semantic representation developed recently to support the development of interpretable natural language applications that require deep semantic analysis of texts. We present the functionalities of UMR-Writer and discuss the challenges in developing such a tool and how they are addressed.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":62,"string":"62"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":57,"string":"57"}}},{"rowIdx":58,"cells":{"question_id":{"kind":"string","value":"Lynne E Parker"},"question":{"kind":"string","value":"Generate an abstract for the title \"Solution space reasoning to improve IQ-ASyMTRe in tightly-coupled multirobot tasks\" using the following items: 1. IQ-ASyMTRe\n2. Coalition formation \n3. Solution space \n4. Efficiency improvements \n5. Robot simulation."},"answer":{"kind":"string","value":"In our prior work, we proposed the IQ-ASyMTRe architecture as a general method to combine coalition formation and execution for tightly-coupled multirobot tasks. IQ ASyMTRe extends the ASyMTRe architecture by introducing several new mechanisms to provide more flexibility for coalition formation as well as to facilitate coalition execution. On the other hand, these mechanisms also change the process of reasoning about solutions and further increase the complexity of the solution space. In this paper, we provide improvements for utilizing the IQ-ASyMTRe architecture based on reasoning about the solution space. We introduce a method in which the exponential growth of the number of potential solutions to be searched can be avoided; instead, the search space is only of linear size for certain tasks. Unnecessary potential solutions are removed to further increase online efficiency. Moreover, the relationships between the created solution space and the complete solution space are studied, and are utilized to provide more coverage of the complete solution space for arbitrary tasks. Although these improvements are discussed with respect to IQ-ASyMTRe, they are also applicable to architectures that approach the generality that IQ-ASyMTRe achieves. Robot simulation and experimental results are provided to demonstrate that the generation and searching of the solution space can be done online (which was impractical previously even for tasks with relatively modest complexities) for certain tasks, and to illustrate how our approach impacts the solution space."},"correct_answer":{"kind":"string","value":"In our prior work, we proposed the IQ-ASyMTRe architecture as a general method to combine coalition formation and execution for tightly-coupled multirobot tasks. IQ ASyMTRe extends the ASyMTRe architecture by introducing several new mechanisms to provide more flexibility for coalition formation as well as to facilitate coalition execution. On the other hand, these mechanisms also change the process of reasoning about solutions and further increase the complexity of the solution space. In this paper, we provide improvements for utilizing the IQ-ASyMTRe architecture based on reasoning about the solution space. We introduce a method in which the exponential growth of the number of potential solutions to be searched can be avoided; instead, the search space is only of linear size for certain tasks. Unnecessary potential solutions are removed to further increase online efficiency. Moreover, the relationships between the created solution space and the complete solution space are studied, and are utilized to provide more coverage of the complete solution space for arbitrary tasks. Although these improvements are discussed with respect to IQ-ASyMTRe, they are also applicable to architectures that approach the generality that IQ-ASyMTRe achieves. Robot simulation and experimental results are provided to demonstrate that the generation and searching of the solution space can be done online (which was impractical previously even for tasks with relatively modest complexities) for certain tasks, and to illustrate how our approach impacts the solution space."},"documents":{"kind":"list like","value":["Title: Decision making as optimization in multi-robot teams\nYear: 2012\n\nAbstract: A key challenge in multi-robot teaming research is determining how to properly enable robots to make decisions on actions they should take to contribute to the overall system objective. This article discusses how many forms of decision making in multi-robot teams can be formulated as optimization problems. In particular, we examine the common multi-robot capabilities of task allocation, path planning, formation generation, and target tracking/observation, showing how each can be represented as optimization problems. Of course, globally optimal solutions to such formulations are not possible, as it is well-known that such problems are intractable. However, many researchers have successfully built solutions that are approximations to the global problems, which work well in practice. While we do not argue that all decision making in multi-robot systems should be based on optimization formulations, it is instructive to study when this technique is appropriate. Future development of new approximation algorithms to well-known global optimization problems can therefore have an important positive impact for many applications in multi-robot systems.","Title: Distributed Cooperative Outdoor Multirobot Localization and Mapping\nYear: 2004\n\nAbstract: The subject of this article is a scheme for distributed outdoor localization of a team of robots and the use of the robot team for outdoor terrain mapping. Localization is accomplished via Extended Kalman Filtering (EKF). In the distributed EKF-based scheme for localization, heterogeneity of the available sensors is exploited in the absence or degradation of absolute sensors aboard the team members. The terrain mapping technique then utilizes localization information to facilitate the fusion of vision-based range information of environmental features with changes in elevation profile across the terrain. The result is a terrain matrix from which a metric map is then generated. The proposed algorithms are implemented using field data obtained from a team of robots traversing an uneven outdoor terrain.","Title: Robopedia: Leveraging Sensorpedia for web-enabled robot control\nYear: 2010\n\nAbstract: There is a growing interest in building Internet- scale sensor networks that integrate sensors from around the world into a single unified system. In contrast, robotics applica- tion development has primarily focused on building specialized systems. These specialized systems take scalability and reliabil- ity into consideration, but generally neglect exploring the key components required to build a large scale system. Integrating robotic applications with Internet-scale sensor networks will unify specialized robotics applications and provide answers to large scale implementation concerns. We focus on utilizing Internet-scale sensor network technology to construct a frame- work for unifying robotic systems. Our framework web-enables a surveillance robot's sensor observations and provides a web- interface to the robot's actuators. This lets robots seamlessly integrate into web applications. In addition, the framework eliminates most prerequisite robotics knowledge, allowing for the creation of general web-based robotics applications. The framework also provides mechanisms to create applications that can interface with any robot. Frameworks such as this one are key to solving large scale mobile robotics implemen- tation problems. We provide an overview of previous Internet- scale sensor networks, Sensorpedia (an ad-hoc Internet-scale sensor network), our framework for integrating robots with Sensorpedia, two applications which illustrate our frameworks ability to support general web-based robotic control, and offer experimental results that illustrate our framework's scalability, feasibility, and resource requirements. I. INTRODUCTION","Title: Tightly-Coupled Navigation Assistance in Heterogeneous Multi-Robot Teams\nYear: 2004\n\nAbstract: This paper presents the design and results of autonomous behaviors for tightly-coupled cooperation in het- erogeneous robot teams, specifically for the task of navigat ion assistance. These cooperative behaviors enable capable, sensor- rich (\"leader\") robots to assist in the navigation of sensor-limited (\"simple\") robots that have no onboard capabilities for obstacle avoidance or localization, and only minimal capabilities for kin recognition. The simple robots must be dispersed throughout a known, indoor environment to serve as a sensor network. However, because of their navigation limitations, they are unable to autonomously disperse themselves or move to planned sensor deployment positions independently. To address this challenge, we present cooperative behaviors for heterogeneous robots that enable the successful deployment of sensor-limited robots by assistance from more capable leader robots. These heteroge- neous cooperative behaviors are quite complex, and involve the combination of several behavior components, including vision- based marker detection, autonomous teleoperation, color marker following in robot chains, laser-based localization, map-based path planning, and ad hoc mobile networking. We present the results of the implementation and extensive testing of these behaviors for deployment in a rigorous test environment. To our knowledge, this is the most complex heterogeneous robot team cooperative task ever attempted on physical robots. We consider it a significant success to have achieved such a high degree of system effectiveness, given the complexity of the overall heterogeneous system.","Title: ASyMTRe: Automated Synthesis of Multi-Robot Task Solutions through Software Reconfiguration\nYear: 2005\n\nAbstract: This paper describes a methodology for automat ically synthesizing task solutions for heterogeneous multi-robot teams. In contrast to prior approaches that require a manual pre definition of how the robot team will accomplish its task (while perhaps automating who performs which task), our approach automates both the how and the who to generate task solution approaches that were not explicitly defined by the designer a priori. The advantages of this new approach are that it: (1) enables the robot team to synthesize new task solutions that use fundamentally different combinations of robot behaviors for different team compositions, and (2) provides a general mechanism for sharing sensory information across networked robots, so that more capable robots can assist less capable robots in accomplishing their objectives. Our approach, which we call ASyMTRe (Automated Synthesis of Multi-robot Task solutions through software Reconfiguration, pronounced “Asymmetry”), is based on mapping environmental, perceptual, and motor control schemas to the required flow of information through the multi-robot system, automatically reconfiguring the connections of schemas within and across robots to synthesize valid and efficient multi-robot behaviors for accomplishing the team objectives. We validate this approach by presenting the results of applying our methodology to two different teaming scenarios: altruistic cooperation involving multi-robot transportation, and coalescent cooperation involving multi-robot box pushing.","Title: Designing Control Laws for Cooperative Agent Teams\nYear: 1993\n\nAbstract: The design of the control laws governing the behavior of individual agents is crucial for the successful development of cooperative agent teams. These control laws utilize a combination of local and/or global knowledge to achieve the resulting group behavior. A key difficulty in this development is determining the appropriate balance between the use of global information and the use of local information to achieve coherent cooperation without excessive communication requirements. This paper...","Title: Multi-robot task scheduling\nYear: 2013\n\nAbstract: The scheduling problem has been studied extensively in the literature. Many algorithms have been developed to operate with different types of processors and tasks. In the robotics domain, when considering each robot as a processor, some of these algorithms can be directly adapted. However, most of the existing algorithms can only handle single-robot tasks, or multi-robot tasks that can be divided into single-robot tasks. As the task requirements may only be partially known, and the available (heterogeneous) robots can dynamically change, robots may be required to cooperate tightly to share different capabilities (i.e., sensors and motors). In such cases, considering scheduling for individual robots is no longer sufficient, since the robots need to work at the coalition level. Although there exist a few algorithms that also support these more complex cases, they do not represent efficient solutions that can be adapted by various multi-robot systems in a convenient manner. In this paper, we propose heuristics to address the multi-robot task scheduling problem at the coalition level, which hides the details of robot specifications, thus allowing these heuristics to be incorporated straightforwardly. These heuristics are easy to implement and efficient enough to run in real time. We provide formal analyses and simulation results to demonstrate and compare their performances.","Title: Zebrafish Larva Locomotor Activity Analysis Using Machine Learning Techniques\nYear: 2013\n\nAbstract: Zebra fish larvae have become a popular model organism to investigate genetic and environmental factors affecting behavior. However, difficulties exist in the analysis of complex behaviors from a large array of larvae. In this paper, we present the new application of machine learning techniques in bioinformatics to automatically detect and investigate the locomotor activities of zebra fish larvae. To achieve this, twelve features were defined and seven unsupervised learning methods were implemented. Next, seven performance measures were applied to evaluate and compare these methods. In order to empirically evaluate the machine learning algorithms, a large dataset was collected that contained 6847 valid instances. Using this dataset, the characteristics of the features were analyzed and the most appropriate unsupervised learning algorithm, i.e., Unweighted Pair Group Method with Arithmetic mean (UPGMA), for locomotor activity analysis was identified. In addition, UPGMA's ability to reveal underlying patterns of zebra fish locomotor activities was demonstrated. In general, this study shows that machine learning techniques have the potential to construct effective, high-throughput systems to automate the process of identifying zebra fish behaviors influenced by genetic manipulation, pharmaceuticals, and environmental toxins.","Title: Distributed sensor analysis for fault detection in tightly-coupled multi-robot team tasks\nYear: 2009\n\nAbstract: This paper presents a distributed version of our previous work, called SAFDetection, which is a sensor analysis-based fault detection approach that is used to monitor tightly-coupled multi-robot team tasks.While the centralized version of SAFDetection was shown to be successful, a shortcoming of the approach is that it does not scale well to large team sizes. The distributed SAFDetection approach addresses this problem by adapting and distributing the approach across team members. Distributed SAFDetection has the same theoretic foundation as centralized SAFDetection, which maps selected robot sensor data to a robot state by using a clustering algorithm, and builds state transition diagrams to describe the normal behavior of the robot system. However, rather than processing multiple robots' sensor data centralized on a server, distributed SAFDetection performs feature selection and clustering on individual robots to build the normal behavior model of an individual robot and the entire robot team. Fault detection is also accomplished in a distributed manner. We have implemented this distributed approach on a physical robot team and in simulation. This paper presents the results of these experiments, showing that distributed SAFDetection is an efficient approach to detect both local and interactive faults in tightly-coupled multi-robot team tasks. Compared to the centralized version, this approach provides more scalability and reliability.","Title: A Complete Methodology for Generating Multi-Robot Task Solutions using ASyMTRe-D and Market-Based Task Allocation\nYear: 2007\n\nAbstract: This paper presents an approach that enables heterogeneous robots to automatically form groups as needed to generate both strongly-cooperative and weakly-cooperative multi-robot task solutions in the same application. The fundamental contribution of this work is the layering of our low-level coalition formation algorithm for generating strongly-cooperative task solutions, with high-level, traditional task allocation methods for weakly-cooperative task solutions. At the low level, coalitions that generate strongly-cooperative multi-robot task solutions are formed using our ASyMTRe-D approach that maps environmental sensors and perceptual and motor schemas to the required flow of information in the robot team, automatically reconfiguring the connections of schemas within and across robots to form efficient solutions. At the high level, a traditional task allocation approach is used to enable individual robots and/or coalitions to compete for weakly-cooperative task assignments through task allocation. We introduce the site clearing task to motivate the work, and then formalize the problem. We then present the approach of layering ASyMTRe-D with task allocation. We validate the approach on a team of robots with the site clearing task. We believe the resulting approach is a flexible system that can handle a broad range of realistic multi-robot applications beyond what is possible using other existing approaches.","Title: Sensor Analysis For Fault Detection In Tightly-Coupled Multi-Robot Team Tasks\nYear: 2007\n\nAbstract: This paper presents a sensor analysis based fault detection approach (which we call SAFDetection) that is used to monitor tightly-coupled multi-robot team tasks. Our approach aims at detecting both physical and logic faults of a robot system with little prior knowledge on the system. We do not need the motion model or a priori knowledge of the possible fault types of the monitored system. Our approach treats the monitored robot system as a black box, with only sensor data available. Thus, we believe the approach is general, and can be used in a wide variety of robot systems performing many different kinds of tasks. Our approach combines data clustering techniques with the generation of a probabilistic state diagram to model the normal operation of the multi-robot system. We have implemented this approach on a physical robot team. This paper presents the results of these experiments, which show that sensor data analyzed from a training phase of normal operation can be used to generate a model of normal robot team operation. This model can then be used to detect many types of abnormal behavior of the system, based purely on monitoring the sensor data of the system.","Title: IQ-ASyMTRe: Forming Executable Coalitions for Tightly Coupled Multirobot Tasks\nYear: 2013\n\nAbstract: While most previous research on forming coalitions mainly concentrates on loosely coupled multirobot tasks, a more challenging problem is to address tightly coupled multirobot tasks that involve close robot coordinations, which often require capability sharing. General methods for autonomous capability sharing have been shown to greatly improve the flexibility of distributed systems. However, in addition to the interaction constraints between the robots and the environment as required by the tasks, these methods may introduce additional interaction constraints between the robots based on how the capabilities are shared. The satisfiability of these constraints in the current situation determines the feasibility of the potential coalitions. To achieve system autonomy, the ability to identify the potential coalitions that are feasible for task execution is critical. In this paper, we demonstrate a general approach that incorporates this capability based on the ASyMTRe architecture. The extended architecture, which is called IQ-ASyMTRe, is able to find coalitions in which these required constraints are satisfied. When used to form coalitions, IQ-ASyMTRe sets up only feasible coalitions, thus enabling tasks to be executed autonomously. We formally present the new architecture and prove that it is sound and complete, given certain assumptions. Simulations and experimental results are provided for different applications in which the robots are able to flexibly form coalitions that are ready to execute.","Title: Approximate l-Fold Cross-Validation with Least Squares SVM and Kernel Ridge Regression\nYear: 2013\n\nAbstract: Kernel methods have difficulties scaling to large modern data sets. The scalability issues are based on computational and memory requirements for working with a large matrix. These requirements have been addressed over the years by using low-rank kernel approximations or by improving the solvers' scalability. However, Least Squares Support Vector Machines (LS-SVM), a popular SVM variant, and Kernel Ridge Regression still have several scalability issues. In particular, the O(n^3) computational complexity for solving a single model, and the overall computational complexity associated with tuning hyper parameters are still major problems. We address these problems by introducing an O(nlog n) approximate l-fold cross-validation method that uses a multi-level circulant matrix to approximate the kernel. In addition, we prove our algorithm's computational complexity and present empirical runtimes on data sets with approximately one million data points. We also validate our approximate method's effectiveness at selecting hyper parameters on real world and standard benchmark data sets. Lastly, we provide experimental results on using a multi level circulant kernel approximation to solve LS-SVM problems with hyper parameters selected using our method.","Title: Considering inter-task resource constraints in task allocation\nYear: 2013\n\nAbstract: This paper focuses on task allocation with single-task robots, multi-robot tasks and instantaneous assignment, which has been shown to be strongly NP-hard. Although this problem has been studied extensively, few efficient approximation algorithms have been provided due to its inherent complexity. In this paper, we first provide discussions and analyses for two natural greedy heuristics for solving this problem. Then, a new greedy heuristic is introduced, which considers inter-task resource constraints to approximate the influence between different assignments in task allocation. Instead of only looking at the utility of the assignment, our approach computes the expected loss of utility (due to the assigned robots and task) as an offset and uses the offset utility for making the greedy choice. A formal analysis is provided for the new heuristic, which reveals that the solution quality is bounded by two different factors. A new algorithm is then provided to approximate the new heuristic for performance improvement. Finally, for more complicated applications, we extend this problem to include general task dependencies and provide a result on the hardness of approximating this new formulation. Comparison results with the two natural heuristics in simulation are provided for both formulations, which show that the new approach achieves improved performance.","Title: Task allocation with executable coalitions in multirobot tasks\nYear: 2012\n\nAbstract: In our prior work, we proposed the IQ-ASyMTRe architecture with a measure of information quality to reason about forming coalitions in multirobot tasks. The formed coalitions are guaranteed to be executable, given the current configurations of the robots and environment. A cost and a quality measure are associated with each coalition to further determine its utility for the task. In this paper, we show that IQ-ASyMTRe-like architectures can be utilized to significantly reduce the overall complexity of task allocation by considering only executable coalitions. For implementation, we apply a layering technique such that most existing methods for task allocation can be easily incorporated. Furthermore, we introduce a general process to address situations in which no executable coalitions are available for certain tasks, and integrate it with IQ-ASyMTRe to achieve more autonomy. Such an approach is able to autonomously decompose unsatisfied preconditions of the required task behaviors into satisfiable components, in order to generate partial order plans for them accordingly. We show how this process can be implemented using a market-based approach. Simulation results are provided to demonstrate these techniques.","Title: Experiments with a Large Heterogeneous Mobile Robot Team: Exploration, Mapping, Deployment and Detection\nYear: 2006\n\nAbstract: We describe the design and experimental validation of a large heterogeneous mobile robot team built for the DARPA Software for Distributed Robotics (SDR) program. The core challenge for the SDR program was to develop a multi-robot system capable of carrying out a specific mission: to deploy a large number of robots into an unexplored building, map the building interior, detect and track intruders, and transmit all of the above information to a remote operator. To satisfy these requirements, we developed a heterogeneous robot team consisting of approximately 80 robots. We sketch the key technical elements of this team, focusing on the novel aspects, and present selected results from supervised experiments conducted in a 600 m 2 indoor environment.","Title: Detecting time-related changes in Wireless Sensor Networks using symbol compression and Probabilistic Suffix Trees\nYear: 2010\n\nAbstract: Our research focuses on anomaly detection problems in unknown environments using Wireless Sensor Networks (WSN). We are interested in detecting two types of abnormal events: sensory level anomalies (e.g., noise in an office without lights on) and time-related anomalies (e.g., freezing temperature in a mid-summer day).We present a novel, distributed, machine learning based anomaly detector that is able to detect time-related changes. It consists of three components. First, a Fuzzy Adaptive Resonance Theory (ART) neural network classifier is used to label multi-dimensional sensor data into discrete classes and detect sensory level anomalies. Over time, the labeled classes form a sequence of classes. Next, a symbol compressor is used to extract the semantic meaning of the temporal sequence. Finally, a Variable Memory Markov (VMM) model in the form of a Probabilistic Suffix Tree (PST) is used to model and detect time-related anomalies in the environment. To our knowledge, this is the first work that analyzes/models the temporal sensor data using a symbol compressor and PST in a WSN. Our proposed detection algorithm is distributed, “light-weight”, and practical for resource constrained sensor nodes. We verify the proposed approach using a volcano monitoring dataset. Our results show that this approach yields the same performance as the traditional Markov models with much less cost.","Title: Quantitative and Qualitative Comparison of Three Laser-Range Mapping Algorithms Using Two Types of Laser Scanner Data\nYear: 2000\n\nAbstract: This paper presents our initial results in comparing three algorithms for autonomous robotic mapping using two types of laser scanner data. The algorithms compared are the Markov localization approach of Thrun, the Lu and Milios iterative dual correspondence algorithm, and the Touzet model-free landmark extraction algorithm. The two types of laser scanner data utilized are the AccuRange laser scanner from Acuity and the SICK laser scanner. We compare these algorithms in terms of the quality of mapped results, computational requirements, and sensitivity to data and odometry error. While the complete comparison of these algorithms on all these measures is not yet accomplished; our results to date indicate that laser mapping algorithms are not immediately transferrable from one type of laser scanner data to another. Instead, algorithms appear to make implicit assumptions on the quality or content of laser data that play a strong role in the quality of the mapping results.","Title: Multi-Robot Team Design for Real-World Applications.\nYear: 1996\n\nAbstract: Real-world applications that are ideal for robotic solutions are very complex and challenging. Manyof these applications are set in dynamic environments that require capabilities distributed in functionality,space, or time. These applications, therefore, often require teams of robots to work togethercooperatively to successfully address the mission. While much research in recent years has addressedthe issues of autonomous robots and multi-robot cooperation, current robotics technology is...","Title: Distributed Algorithms for Multi-Robot Observation of Multiple Moving Targets\nYear: 2002\n\nAbstract: An important issue that arises in the automation of many security, surveillance, and reconnaissance tasks is that of observing the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement—determining where sensors should be located to maintain the targets in view. In complex applications involving limited-range sensors, the use of multiple sensors dynamically moving over time is required. In this paper, we investigate the use of a cooperative team of autonomous sensor-based robots for the observation of multiple moving targets. In other research, analytical techniques have been developed for solving this problem in complex geometrical environments. However, these previous approaches are very computationally expensive—at least exponential in the number of robots—and cannot be implemented on robots operating in real-time. Thus, this paper reports on our studies of a simpler problem involving uncluttered environments—those with either no obstacles or with randomly distributed simple convex obstacles. We focus primarily on developing the on-line distributed control strategies that allow the robot team to attempt to minimize the total time in which targets escape observation by some robot team member in the area of interest. This paper first formalizes the problem (which we term CMOMMT for iCooperative Multi-Robot Observation of Multiple Moving Targets) and discusses related work. We then present a distributed heuristic approach (which we call A-CMOMMT) for solving the CMOMMT problem that uses weighted local force vector control. We analyze the effectiveness of the resulting weighted force vector approach by comparing it to three other approaches. We present the results of our experiments in both simulation and on physical robots that demonstrate the superiority of the A-CMOMMT approach for situations in which the ratio of targets to robots is greater than 1/2. Finally, we conclude by proposing that the CMOMMT problem makes an excellent domain for studying multi-robot learning in inherently cooperative tasks. This approach is the first of its kind for solving the on-line cooperative observation problem and implementing it on a physical robot team.","Title: Real-time multiple human perception with color-depth cameras on a mobile robot.\nYear: 2013\n\nAbstract: The ability to perceive humans is an essential requirement for safe and efficient human-robot interaction. In real-world applications, the need for a robot to interact in real time with multiple humans in a dynamic, 3-D environment presents a significant challenge. The recent availability of commercial color-depth cameras allow for the creation of a system that makes use of the depth dimension, thus enabling a robot to observe its environment and perceive in the 3-D space. Here we present a system for 3-D multiple human perception in real time from a moving robot equipped with a color-depth camera and a consumer-grade computer. Our approach reduces computation time to achieve real-time performance through a unique combination of new ideas and established techniques. We remove the ground and ceiling planes from the 3-D point cloud input to separate candidate point clusters. We introduce the novel information concept, depth of interest, which we use to identify candidates for detection, and that avoids the computationally expensive scanning-window methods of other approaches. We utilize a cascade of detectors to distinguish humans from objects, in which we make intelligent reuse of intermediary features in successive detectors to improve computation. Because of the high computational cost of some methods, we represent our candidate tracking algorithm with a decision directed acyclic graph, which allows us to use the most computationally intense techniques only where necessary. We detail the successful implementation of our novel approach on a mobile robot and examine its performance in scenarios with real-world challenges, including occlusion, robot motion, nonupright humans, humans leaving and reentering the field of view (i.e., the reidentification challenge), human-object and human-human interaction. We conclude with the observation that the incorporation of the depth information, together with the use of modern techniques in new ways, we are able to create an accurate system for real-time 3-D perception of humans by a mobile robot.","Title: Cooperative multi-robot observation of multiple moving targets\nYear: 1997\n\nAbstract: An important issue that arises in the automation of many security, surveillance, and reconnaissance tasks is that of monitoring, or observing, the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement-determining where sensors should be located to maintain the targets in view. In complex applications of this type, the use of multiple sensors dynamically moving over time is required. In this paper, we investigate the use of a cooperative team of autonomous sensor-based robots for multi-robot observation of multiple moving targets. We focus primarily on developing the distributed control strategies that allow the robot team to attempt to maximize the collective time during which each object is being observed by at least one robot in the area of interest. Our initial efforts in this problem address the aspects of distributed control in homogeneous robot teams with equivalent sensing and movement capabilities working in an uncluttered, bounded area. This paper first formalizes the problem, discusses related work, and then shows that this problem is NP-hard. We then present a distributed approximate approach to solving this problem that combines low-level multi-robot control with higher-level control. The low-level control is described in terms of force fields emanating from the targets and the robots. The higher level control is presented in the ALLIANCE formalism, which provides mechanisms for fault tolerant cooperative control, and allows robot team members to adjust their low-level actions based upon the actions of their teammates. We then present the results of the implementation of portions of our approach, both in simulation and on physical robots.","Title: On the design of behavior-based multi-robot teams\nYear: 1995\n\nAbstract: Real-world applications that are ideal for robotic solutions are very complex and challenging. Many of these applications are set in dynamic environments that require capabilities distributed in functionality, space or time. These applications, therefore, often require teams of robots to work together cooperatively to successfully address the mission. While much research in recent years has addressed the issues of autonomous robots and multi-robot cooperation, current robotics technology is still far from achieving many of these real world applications. We believe that two primary reasons for this technology gap are that (1) previous work has not adequately addressed the issues of fault tolerance and adaptivity in multi-robot teams, and (2) existing robotics research is often geared at specific applications and is not easily generalized to different, but related, applications. This paper addresses these issues by first describing the design issues of key importance in these real-world cooperative robotics applications - fault tolerance, reliability, adaptivity and coherence. We then present a general architecture addressing these design issues - called ALLIANCE - that facilitates multi-robot cooperation of small- to medium-sized teams in dynamic environments, performing missions composed of loosely coupled subtasks. We illustrate the generality of this architecture by describing two very different proof-of-concept implementations of this architecture: a janitorial service mission and a bounding overwatch mission.","Title: Adaptive heterogeneous multi-robot teams\nYear: 1999\n\nAbstract: This research addresses the problem of achieving fault-tolerant cooperation within small- to medium-sized teams of heterogeneous mobile robots. We describe a novel behavior-based, fully distributed architecture, called ALLIANCE, that utilizes adaptive action selection to achieve fault tolerant cooperative control in robot missions involving loosely coupled tasks. The robots in this architecture possess a variety of high-level functions that they can perform during a mission, and must at all times select an appropriate action based on the requirements of the mission, the activities of other robots, the current environmental conditions, and their own internal states. Since such cooperative teams often work in dynamic and unpredictable environments, the software architecture allows the team members to respond robustly and reliably to unexpected environmental changes and modifications in the robot team that may occur due to mechanical failure, the learning of new skills, or the addition or removal of robots from the team by human intervention. After presenting ALLIANCE, we describe in detail our experimental results of an implementation of this architecture on a team of physical mobile robots performing a cooperative box pushing demonstration. These experiments illustrate the ability of ALLIANCE to achieve adaptive, fault-tolerant cooperative control amidst dynamic changes in the capabilities of the robot team.","Title: Peer-to-Peer Human-Robot Teaming through Reconfigurable Schemas\nYear: 2006\n\nAbstract: This position paper presents our ongoing work of developing mechanisms to facilitate human-robot teaming with a focus on peer-to-peer interaction. We have developed an approach that autonomously configures solutions for multi-robot teams based on the team capabilities and the task objective. With the success of this approach in simulation and on physical robots, we plan to extend it to address several challenging issues in human-robot teaming. a dialogue system to facilitate the interaction; computational cognitive architectures that model humans to enhance the understanding between humans and robots; and a series of evaluation methods. This project is currently the most com- prehensive work that deals with most of the issues in human- robot teaming. The objective of our work is to explore an alternative way of interaction based on the information that team members need to exchange to accomplish the task col- laboratively.","Title: Lifelong Adaptation in Heterogeneous Multi-Robot Teams: Response to Continual Variation in Individual Robot Performance\nYear: 2000\n\nAbstract: Generating teams of robots that are able to perform their tasks over long periods of time requires the robots to be responsive to continual changes in robot team member capabilities and to changes in the state of the environment and mission. In this article, we describe the L-ALLIANCE architecture, which enables teams of heterogeneous robots to dynamically adapt their actions over time. This architecture, which is an extension of our earlier work on ALLIANCE, is a distributed, behavior-based architecture aimed for use in applications consisting of a collection of independent tasks. The key issue addressed in L-ALLIANCE is the determination of which tasks robots should select to perform during their mission, even when multiple robots with heterogeneous, continually changing capabilities are present on the team. In this approach, robots monitor the performance of their teammates performing common tasks, and evaluate their performance based upon the time of task completion. Robots then use this information throughout the lifetime of their mission to automatically update their control parameters. After describing the L-ALLIANCE architecture, we discuss the results of implementing this approach on a physical team of heterogeneous robots performing proof-of-concept box pushing experiments. The results illustrate the ability of L-ALLIANCE to enable lifelong adaptation of heterogeneous robot teams to continuing changes in the robot team member capabilities and in the environment.","Title: Behavior-Based Cooperative Robotics Applied to Multi-Target Observation\nYear: 1996\n\nAbstract: this paper, we investigate the useof a cooperative team of autonomous sensor-based robots for the observation of multiplemoving targets. We focus primarily on developing the distributed control strategies thatallow the robot team to attempt to minimize the total time in which targets escapeobservation by some robot team member in the area of interest. Our initial efforts onthis problem address the aspects of distributed control in homogeneous robot teams withequivalent sensing and...","Title: Heterogeneous Mobile Sensor Net Deployment Using Robot Herding And Line-Of-Sight Formations\nYear: 2003\n\nAbstract: This paper presents an approach for deploying a team of mobile sensor nodes to form a sensor network in indoor environments. The challenge in this work is that the mobile sensor nodes have no ability for localization or obstacle avoidance. Thus, our approach entails the use of more capable \"helper\" robots that \"herd\" the mobile sensor nodes into their deployment positions. To extensively explore the issues of heterogeneity in multi-robot teams, we employ the use of two types of helper robots - one that acts as a leader and a second that: 1) acts as a follower and 2) autonomously teleoperates the mobile sensor nodes. Due to limited sensing capabilities, neither of these helper robots can herd the mobile sensor nodes alone; instead, our approach enables the team as a whole to successfully accomplish the sensor deployment task. Our approach involves the use of line-of-sight formation keeping, which enables the follower robot to use visual markers to move the group along the path executed by the leader robot We present results of the implementation of this approach in simulation, as well as results to date in the implementation on physical robot systems. To our knowledge, this is the first implementation of robot herding using such highly heterogeneous robots, in which no single type of robot could accomplish the sensor network deployment task, even if multiple copies of that robot type were available.","Title: A general information quality based approach for satisfying sensor constraints in multirobot tasks\nYear: 2010\n\nAbstract: Many architectures have been proposed to solve tightly-coupled multirobot tasks (MT) through coalitions of heterogeneous robots. However, several issues remain unaddressed. As coalitions are formed, sensor constraints among robots are also established. For example, in a leader-follower task, follower robots must keep leader robots within their sights, while in a box-pushing task, a supervisor robot needs to track the moving direction of the box and monitor the pushing path to the goal for obstacle avoidance. The question of how to keep these constraints satisfied during the entire execution, from initial configurations to completeness of the task, remains an open issue. In addition, environmental factors, both static and dynamic, can influence the maintenance of the constraints. Moreover, problems arise when the constraints are unsatisfiable given the current circumstances. For example, the sight of the leader might be blocked or there might be obstacles blocking the view of the box. This paper proposes a general method to address these issues for various applications with sensors having certain characteristics. Our approach combines the use of sensor models, environment sampling, measures of information quality, a motion model with sampling, and a constraint model. We believe that this approach offers the first generic formulation of robotic sensor constraints that can be applied to a wide variety of applications. To illustrate this method, we apply the approach to solve robot tracking and navigation tasks both in simulation and with physical robots. Experimental results illustrate the flexibility and robustness of the approach.","Title: A Decentralized Architecture for Multi-Robot Systems Based on the Null-Space-Behavioral Control with Application to Multi-Robot Border Patrolling.\nYear: 2013\n\nAbstract: This paper presents a control architecture for multi-robot systems. The proposed architecture has been developed in the framework of the Null-Space-based-Behavioral (NSB) control, a competitive-collaborative behavior-based control approach. The standard NSB statically determines a set of suitably defined elementary tasks (behaviors) and their priorities, i.e., they cannot be dynamically changed according to mission requirements and environmental constraints. In this paper, a three layer architecture has been designed in order to avoid such a drawback. The single robotic unit (agent) performing the mission is placed on the lower layer. In the middle layer, suitably defined elementary are defined; these elementary are then combined, via the NSB approach, in more complex . The upper layer is a Supervisor in charge of dynamically selecting the proper action to be executed. As further contribution, the architecture has been applied to the multi-robot border patrolling mission to generate a decentralized, deterministic and non-communicative solution that is robust to faults, and prevents collisions, even in the case of high robot density. Finally, the simulations on a team composed by a large number of robots, and experiments on a real setup, composed by three Pioneer-3DX robots, are provided.","Title: Adaptive Causal Models For Fault Diagnosis, And Recovery In Multi-Robot Teams\nYear: 2006\n\nAbstract: This paper presents an adaptive causal model method (adaptive CMM) for fault diagnosis and recovery in complex multi-robot teams. We claim that a causal model approach is effective for anticipating and recovering from many types of robot team errors, presenting extensive experimental results to support this claim. To our knowledge, these results show the first, full implementation of a CMM on a large multi-robot team. However, because of the significant number of possible failure modes in a complex multi-robot application, and the difficulty in anticipating all possible failures in advance, our empirical results show that one cannot guarantee the generation of a complete a priori causal model that identifies and specifies all faults that may occur in the system. Instead, an adaptive method is needed to enable the robot team to use its experience to update and extend its causal model to enable the team, over time, to better recover from faults when they occur. We present our case-based learning approach, called LeaF (for Learning-based Fault diagnosis), that enables robot team members to adapt their causal models, thereby improving their ability to diagnose and recover from these faults over time.","Title: Distributed Intelligence: Overview of the Field and its Application in Multi-Robot Systems\nYear: 2007\n\nAbstract: This paper introduces the concepts of distributed intelligence, outlining the motivations for studying this field of research. We then classify common systems of distributed intelligence based upon the types of interactions exhibited, since the type of interaction has relevance to the solution paradigm to be used. We outline three common paradigms for distributed intelligence — the bioinspired paradigm, the organizational and social paradigm, and the knowledge-based, ontological paradigm — and give examples of how these paradigms can be used in multi-robot systems. We then look at a common problem in multi-robot systems — that of task allocation — and show how the solution approach to this problem is very different depending upon the paradigm chosen for abstract- ing the problem. Our conclusion is that the paradigms are not interchangeable, but rather the selection of the appropri- ate paradigm is dependent upon the specific constraints and requirements of the application of interest. Further work is needed to provide guidance to the system designer on select- ing the proper abstraction, or paradigm, for a given problem.","Title: A Reinforcement Learning Algorithm in Cooperative Multi-Robot Domains\nYear: 2005\n\nAbstract: Reinforcement learning has been widely applied to solve a diverse set of learning tasks, from board games to robot behaviours. In some of them, results have been very successful, but some tasks present several characteristics that make the application of reinforcement learning harder to define. One of these areas is multi-robot learning, which has two important problems. The first is credit assignment, or how to define the reinforcement signal to each robot belonging to a cooperative team depending on the results achieved by the whole team. The second one is working with large domains, where the amount of data can be large and different in each moment of a learning step. This paper studies both issues in a multi-robot environment, showing that introducing domain knowledge and machine learning algorithms can be combined to achieve successful cooperative behaviours.","Title: Distributed Multi-Agent Diagnosis And Recovery From Sensor Failures\nYear: 2003\n\nAbstract: This paper presents work extending previous research in sensor fault tolerance, classification, and recovery from a single robot to a heterogeneous team of distributed robots. This approach allows teams of robots to share knowledge about the working environment, sensor and task state, to diagnose failures and also communicate to redistribute tasks in the event that a robot becomes inoperable. Our work presents several novel extensions to prior art: distributed fault handling and task management in a dynamic, distributed Java framework. This research was implemented and demonstrated on robots in a lab environment performing a simplified search operation.","Title: IQ-ASyMTRe: Synthesizing coalition formation and execution for tightly-coupled multirobot tasks\nYear: 2010\n\nAbstract: This paper presents the IQ-ASyMTRe architecture, which is aimed to address both coalition formation and execution for tightly-coupled multirobot tasks in a single framework. Many task allocation algorithms have been previously proposed without explicitly enabling the sharing of robot capabilities. Inspired by information invariant theory, ASyMTRe was introduced which enables the sharing of sensory and computational capabilities by allowing information to flow among different robots via communication. However, ASyMTRe does not provide a solution for how a coalition should satisfy sensor constraints introduced by the sharing of capabilities while executing the assigned task. Furthermore, conversions among different information types are hardcoded, which limits the flexibility of ASyMTRe. Moreover, relationships between entities (e.g., robots) and information types are not explicitly captured, which may produce infeasible solutions from the start, as the defined information type may not correspond well to the current environment settings. The new architecture introduces a complete definition of information type to guarantee the feasibility of solutions; it also explicitly models information conversions. Inspired by our previous work, IQ-ASyMTRe uses measures of information quality to guide robot coalitions to satisfy sensor constraints (introduced by capability sharing) while executing tasks, thus providing a complete and general solution. We demonstrate the capability of the approach both in simulation and on physical robots to form and execute coalitions that share sensory information to achieve tightly-coupled tasks.","Title: Estimating building simulation parameters via Bayesian structure learning\nYear: 2013\n\nAbstract: Many key building design policies are made using sophisticated computer simulations such as EnergyPlus (E+), the DOE flagship whole-building energy simulation engine. E+ and other sophisticated computer simulations have several major problems. The two main issues are 1) gaps between the simulation model and the actual structure, and 2) limitations of the modeling engine's capabilities. Currently, these problems are addressed by having an engineer manually calibrate simulation parameters to real world data or using algorithmic optimization methods to adjust the building parameters. However, some simulations engines, like E+, are computationally expensive, which makes repeatedly evaluating the simulation engine costly. This work explores addressing this issue by automatically discovering the simulation's internal input and output dependencies from ~20 Gigabytes of E+ simulation data, future extensions will use ~200 Terabytes of E+ simulation data. The model is validated by inferring building parameters for E+ simulations with ground truth building parameters. Our results indicate that the model accurately represents parameter means with some deviation from the means, but does not support inferring parameter values that exist on the distribution's tail.","Title: On the design and development of a human-robot synergistic system\nYear: 1992\n\nAbstract: A great variety of robotic systems have been developed over the past decades, varying from fully human-controlled teleoperated systems, to fully motion-programmed, industrial-type devices, to sensor-equipped ‘intelligent’ machines with autonomous perception and reasoning capabilities. All these systems, however, have very static roles in supporting humans, in the sense that their capabilities are limited to very narrow functions or tasks domains and they cannot really adapt to changing environments where entirely new tasks may be necessary. By considering these systems as part of overall human-machine systems, interesting adaptation capabilities can be envisioned for the machine through the sharing of control and experiences, and observation of the human actions. This paper proposes a general conceptual architecture for enhancing the synergy between humans and machines in such cooperative systems, and investigates an implementation of the concept to the synergistic integration of teleoperative and autonomous operation of a manipulator arm for the execution of sequential tasks. The proposed architecture reflects a unique blend of many disciplines of artificial or machine intelligence and the functioning of its major modules is discussed. The paper then focuses on initial implementations of the Job Planner, Task Allocator, and Execution Monitor modules to discuss simple proof-of-principle experiments illustrating the coalescence of these modules needed to achieve skill-based dynamic task planning, allocation, and execution.","Title: Evaluating success in autonomous multi-robot teams: experiences from ALLIANCE architecture implementations\nYear: 2001\n\nAbstract: A current limitation in multi-robot systems research is the lack of metrics that enable the performance comparison of various approaches to cooperative control. Ideally, metrics would be available that provide quantitative evaluations of cooperative robot teams based upon high-level design goals, such as fault tolerance, adaptivity, and so forth. In current research, however, metrics are limited to application-dependent measures. This paper summarizes the metrics that have been used in eight implementations of the ALLIANCE architecture in multi-robot teams. We explore the implications of the chosen metrics and offer suggestions for developing less application-dependent metrics in the future.","Title: The SDR Experience: Experiments with a Large-Scale Heterogeneous Mobile Robot Team\nYear: 2004\n\nAbstract: This paper reports on experiments conducted as part of the DARPA SDR (Software for Distributed Robotics) program. The core challenge for this program is to develop a system capable of carrying out 'locate-and-protect' missions: the system must be able to deploy a large number of robots into an unexplored building, map the building interior, locate a valued object, detect and track intruders, and transmit all of the above information to a remote observer/operator. To satisfy these requirements, we have developed a large heterogeneous robot team consisting of approximately 80 robots. This paper sketches the key technical elements of this system, and presents selected results from externally supervised experiments conducted in a 600 m2 indoor environment.","Title: Planning mobile sensor net deployment for navigationally-challenged sensor nodes\nYear: 2004\n\nAbstract: This wok describes novel algorithms for planning the deployment of a large number of navigationally-challenged mobile sensor nodes in known indoor environments. Due to cost and power constraints, our mobile sensor nodes have the ability to move and communicate, but they cannot detect or avoid obstacles or localize to the environment. Additionally, they have only minimal capabilities for detecting other robot team members, through the use of a crude camera. Our deployment process, therefore, uses an assistive navigation technique that enables a more capable leader robot, equipped with a laser rangefinder and a camera, to guide several mobile sensor nodes to their deployment positions. To ensure the successful deployment of the mobile sensor nodes, we have developed an autonomous planning process that plans the positions of the sensor nodes based upon a number of constraints, including maintaining line of sight maximizing visibility coverage, avoiding placement in doorways, minimizing obstruction of corridors, and so forth. Additionally, because of the navigational constraints of simple robots following a leader to these deployment positions, our algorithm also derives two leader waypoints for each sensor position, which on strain the motion of the leader path to the deployment position. These leader","Title: Toward the Automated Synthesis of Cooperative Mobile Robot Teams\nYear: 1998\n\nAbstract: A current limitation in the real-world use of cooperating mobile robots is the difficulty in determining the proper team composition for a given robotic application. Present technology restricts the design and implementation of cooperative robot teams to the expertise of a robotics researcher, who has to develop robot teams on an application-specific basis. The objective of our research is to reduce the complexity of cooperative robotic systems through the development of a methodology that enables the automated synthesis of cooperative robot teams. We propose an approach to this problem that uses a combination of the theories of sensori-computational systems and information invariants, building on the earlier work of Donald, Rus, et al. We describe the notion of defining equivalence classes that serve as fundamental building blocks of more complex cooperative mobile robot behaviors. We postulate a methodology for framing mission requirements in terms of the goals and constraints of the problem, incorporating issues such as multi-robot interference, communication, control strategy, robot complexity, and so forth, into the mechanism. Our initial work restricts the robot application and design space to three multi-robot application domains we have previously studied and implemented: keeping formation, \"mock\" hazardous waste cleanup, and cooperative observation. This paper presents the foundational ideas upon which our approach to cooperative team design is based.","Title: Indoor Target Intercept Using An Acoustic Sensor Network And Dual Wavefront Path Planning\nYear: 2003\n\nAbstract: This paper presents an approach that enables a mobile \"Interceptor\" robot to intercept targets in an indoor environment using information from a distributed acoustic sensor network. The approach assurnes the indoor environment has been previously mapped and that the sensor nodes know their position in the map. The targets are localized in the sensor network based upon local maxima of the acoustic volume. The current target localization information is reported to an Interceptor robot, which utilizes a dual wavefront path planner to move from its current location to a location that is within viisibility range of a target. Results of the complete implementation of this approach using 70 sensor net robots in the Player/Stage multi-robot simulator are reported, as well as implementation results to date on a team of physical robots. To our knowledge, this is the first implementation of a multi-robot system that combines the use of an acoustic sensor net for target detection with an Interceptor robot that can efficiently reach the moving position of the detected target in indoor environments.","Title: Nearest neighbor imputation using spatial-temporal correlations in wireless sensor networks.\nYear: 2014\n\nAbstract: Missing data is common in Wireless Sensor Networks (WSNs), especially with multi-hop communications. There are many reasons for this phenomenon, such as unstable wireless communications, synchronization issues, and unreliable sensors. Unfortunately, missing data creates a number of problems for WSNs. First, since most sensor nodes in the network are battery-powered, it is too expensive to have the nodes re-transmit missing data across the network. Data re-transmission may also cause time delays when detecting abnormal changes in an environment. Furthermore, localized reasoning techniques on sensor nodes (such as machine learning algorithms to classify states of the environment) are generally not robust enough to handle missing data. Since sensor data collected by a WSN is generally correlated in time and space, we illustrate how replacing missing sensor values with spatially and temporally correlated sensor values can significantly improve the network’s performance. However, our studies show that it is important to determine which nodes are spatially and temporally correlated with each other. Simple techniques based on Euclidean distance are not sufficient for complex environmental deployments. Thus, we have developed a novel Nearest Neighbor (NN) imputation method that estimates missing data in WSNs by learning spatial and temporal correlations between sensor nodes. To improve the search time, we utilize a kd-tree data structure, which is a non-parametric, data-driven binary search tree. Instead of using traditional mean and variance of each dimension for kd-tree construction, and Euclidean distance for kd-tree search, we use weighted variances and weighted Euclidean distances based on measured percentages of missing data. We have evaluated this approach through experiments on sensor data from a volcano dataset collected by a network of Crossbow motes, as well as experiments using sensor data from a highway traffic monitoring application. Our experimental results show that our proposed K-NN imputation method has a competitive accuracy with state-of-the-art Expectation–Maximization (EM) techniques, while using much simpler computational techniques, thus making it suitable for use in resource-constrained WSNs.","Title: L-ALLIANCE: Task-Oriented Multi-Robot Learning in Behaviour-Based Systems\nYear: 1996\n\nAbstract: A large application domain for multi-robot teams involves task-oriented missions, in which potentially heterogeneous robots must solve several distinct tasks. Previous research addressing this problem in multi-robot systems has largely focused on issues of efficiency, while ignoring the real-world situated robot needs of fault tolerance and adaptivity. This paper addresses this problem by developing an architecture called L-ALLIANCE that incorporates task-oriented action selection mechanisms into a behavior-based system, thus increasing the efficiency of robot team performance while maintaining the desirable characteristics of fault tolerance and adaptivity. We present our investigations of several competing control strategies and derive an approach that works well in a wide variety of multi-robot task-oriented mission scenarios. We provide a formal model of this technique to illustrate how it can be incorporated into any behavior-based system.","Title: Calibrating building energy models using supercomputer trained machine learning agents\nYear: 2014\n\nAbstract: Building energy modeling BEM is an approach to model the energy usage in buildings for design and retrofit purposes. EnergyPlus is the flagship Department of Energy software that performs BEM for different types of buildings. The input to EnergyPlus can often extend in the order of a few thousand parameters that have to be calibrated manually by an expert for realistic energy modeling. This makes it challenging and expensive thereby making BEM unfeasible for smaller projects. In this paper, we describe the 'Autotune' research that employs machine learning algorithms to generate agents for the different kinds of standard reference buildings in the US building stock. The parametric space and the variety of building locations and types make this a challenging computational problem necessitating the use of supercomputers. Millions of EnergyPlus simulations are run on supercomputers that are subsequently used to train machine learning algorithms to generate agents. These agents, once created, can then run in a fraction of the time thereby allowing cost-effective calibration of building models. Published 2014. This article is a US Government work and is in the public domain in the USA.","Title: Fuzzy segmentation and recognition of continuous human activities\nYear: 2014\n\nAbstract: Most previous research has focused on classifying single human activities contained in segmented videos. However, in real-world scenarios, human activities are inherently continuous and gradual transitions always exist between temporally adjacent activities. In this paper, we propose a Fuzzy Segmentation and Recognition (FuzzySR) algorithm to explicitly model this gradual transition. Our goal is to simultaneously segment a given video into events and recognize the activity contained in each event. Specifically, our algorithm uniformly partitions the video into a sequence of non-overlapping blocks, each of which lasts a short period of time. Then, a multi-variable time series is creatively formed through concatenating the block-level human activity summaries that are computed using topic models over each block's local spatio-temporal features. By representing an event as a fuzzy set that has fuzzy boundaries to model gradual transitions, our algorithm is able to segment the video into a sequence of fuzzy events. By incorporating all block summaries contained in an event, the proposed algorithm determines the most appropriate activity category for each event. We evaluate our algorithm's performance using two real-world benchmark datasets that are widely used in the machine vision community. We also demonstrate our algorithm's effectiveness in important robotics applications, such as intelligent service robotics. For all used datasets, our algorithm achieves promising continuous human activity segmentation and recognition results.","Title: Coalition coordination for tightly coupled multirobot tasks with sensor constraints\nYear: 2014\n\nAbstract: Although many approaches have been developed to form robot coalitions that can achieve a multirobot task, no general methods exist to execute these coalitions, especially when the coordination among the robots is tightly coupled. In this paper, we propose a coordination mechanism as the first step to address coalition execution; it provides a flexible method to reason about synergies with overlapping coalitions (thus enabling multi-tasking robots in multi-robot tasks), which not only improves efficiency, but also reduces resource requirements in task execution. This means that our approach enables tasks that cannot be easily handled before, especially when critical resources are rare but commonly required. Our approach is based on the concept of sensor constraint, which is introduced by the tight coupling (e.g., information sharing) between the robots. We show that our algorithm is sound and complete in finding a coordination solution given a few assumptions, and discuss a distributed implementation. Simulation results are provided to demonstrate the capabilities of this new approach.","Title: Simplex-Based 3D Spatio-temporal Feature Description for Action Recognition\nYear: 2014\n\nAbstract: We present a novel feature description algorithm to describe 3D local spatio-temporal features for human action recognition. Our descriptor avoids the singularity and limited discrimination power issues of traditional 3D descriptors by quantizing and describing visual features in the simplex topological vector space. Specifically, given a feature's support region containing a set of 3D visual cues, we decompose the cues' orientation into three angles, transform the decomposed angles into the simplex space, and describe them in such a space. Then, quadrant decomposition is performed to improve discrimination, and a final feature vector is composed from the resulting histograms. We develop intuitive visualization tools for analyzing feature characteristics in the simplex topological vector space. Experimental results demonstrate that our novel simplex-based orientation decomposition (SOD) descriptor substantially outperforms traditional 3D descriptors for the KTH, UCF Sport, and Hollywood-2 benchmark action datasets. In addition, the results show that our SOD descriptor is a superior individual descriptor for action recognition.","Title: A distributed and optimal motion planning approach for multiple mobile robots\nYear: 2002\n\nAbstract: We propose a distributed and optimal motion planning algorithm for multiple robots. The computationally expensive problem is decomposed into two modules: path planning and velocity planning. The D* search method is applied in both modules, based on either geometric formulation or schedule formulation. Optimization is achieved at the individual robot level by defining cost functions, and also at the team level by a global measurement function reflecting performance indices of interest as a team. Contrary to our knowledge of previous results on multi-robot motion planning that either obtain optimal solutions through centralized and exhaustive computing, or achieve distributed implementations without considering any optimization issues, our approach combines these two features and explicitly optimizes performance functions through a distributed implementation. It is also one of the few that is capable of handling outdoor rough terrain environments and real time replanning. Simulations are shown on a Mars-like rough terrain using a 3D vehicle planner and control simulator. The algorithm was also implemented and successfully run on a group of Nomad 200 indoor robots","Title: Cooperative leader following in a distributed multi-robot system\nYear: 2002\n\nAbstract: The cooperative leader following task for multi-robot teams is introduced and discussed. We describe the design and implementation of a distributed technique to coordinate team level and robot level behaviors for this task, as well as a multi-threaded framework for the implementation of a multi-robot system with heterogeneous sensing capabilities. This approach enables robots to remain in formation as they deal with other obstacles that may appear within the formation. We describe how single robot behaviors are realized and scheduled. We show some of the results of the team implementations. The proposed approach has been run and validated on a team of robots performing both in indoor and outdoor environments","Title: Distributed heterogeneous outdoor multi-robot localization\nYear: 2002\n\nAbstract: An Extended Kalman Filter-based algorithm for the localization of a team of robots is described in this paper. The distributed EKF localization scheme is straightforward in that the individual robots maintain a pose estimate using EKFs that are local to every robot. We then show how these results can be extended to perform heterogeneous cooperative localization in the absence or degradation of absolute sensors aboard the team members. The proposed algorithms are implemented using field data obtained from a team of ATRV-Mini robots traversing on have a fully centralized scheme for the control of mul- tiple robots as the increase in computational overhead is proportional to the number of robots in the team. When there is no central processing facility and all the decisional issues for a team member are tackled within the robot itself, the disadvantages associated with the centralized architectures can be overcome. This moti- vation has manifest itself into decentralized (and dis- tributed) architectures that render robust and modular capabilities (3). Localization, the process of determining the position and orientation (pose) of a robot within the operating environment, is critical for subsequent high level nav- igation tasks. Each member of the robot team con- sidered in this paper possesses absolute positioning ca- pability by means of differential GPS (DGPS). Multi- pathing 1 errors make it extremely difficult to localize based on DGPS alone. Thus it becomes necessary to develop a framework within which observations from dead-reckoning and absolute sensors can be fused to continually deliver reliable and consistent pose esti- mates. Additionally, in order to minimize the com- putational bottlenecks associated with centralized ar- chitectures for multi-robot localization, we seek to de- centralize the estimation process across the members of the group. To achieve the above requirements, a distributed Extended Kalman Filter-based algorithm for the localization of a team of robots operating on outdoor terrain is developed in this paper. In the first part of the paper, we show that distributed localization of robot team members can be realized in a straight- forward manner by enabling each robot to maintain its pose using an EKF that is local to that particular robot. The resulting pose estimates are intended to aid the construction of an elevation map (described in a companion paper (4)). We also consider the case when","Title: Guest editorial advances in multirobot systems\nYear: 2002\n\nAbstract: As research progresses in distributed robotic systems, more and more aspects of multirobot systems are being explored. This Special Issue on Advances in Multirobot Systems provides a broad sampling of the research that is currently ongoing in the field of distributed mobile robot systems. To help categorize this research, we have identified seven primary research topics within multirobot systems: biological inspirations, communication, architectures, localization/mapping/exploration, object transport and manipulation, motion coordination, and reconfigurable robots. This editorial examines these research areas and discusses the Special Issue papers in this context. We conclude by identifying several additional open research issues in distributed mobile robotic systems.","Title: Task-oriented multi-robot learning in behavior-based systems\nYear: 1996\n\nAbstract: A large application domain for multi-robot teams involves task-oriented missions, in which potentially heterogeneous robots must solve several distinct tasks. Previous research addressing this problem in multi-robot systems has largely focused on issues of efficiency, while ignoring the real-world situated robot needs of fault tolerance and adaptivity. This paper addresses this problem by developing an architecture called L-ALLIANCE that incorporates task-oriented action selection mechanisms into a behavior-based system, thus increasing the efficiency of robot team performance while maintaining the desirable characteristics of fault tolerance and adaptivity. We present our investigations of several competing control strategies and derive an approach that works well in a wide variety of multi-robot task-oriented mission scenarios. We provide a formal model of this technique to illustrate how it can be incorporated into any behavior-based system","Title: Building Multirobot Coalitions Through Automated Task Solution Synthesis\nYear: 2006\n\nAbstract: ABSTRACT | This paper,presents,a reasoning,system,that enables,a group,of heterogeneous,robots,to form,coalitions to accomplish,a multirobot task using tightly coupled,sensor sharing. Our approach, which we call ASyMTRe, maps environmental,sensors,and perceptual and motor control schemas,to the required,flow of information,through,the multirobot,system, automatically reconfiguring the connections of schemas within and across robots to synthesize,valid and,efficient multirobot,behaviors,for accomplishing,a multirobot,task. We present,the centralized,anytime,ASyMTRe configuration,algorithm, proving that the algorithm is correct, and formally addressing,issues,of completeness,and,optimality.,We then present a distributed version of ASyMTRe, called ASyMTRe-D, which,uses communication,to enable,distributed,coalition formation. We validate the centralized,approach,by applying,the ASyMTRe methodology,to two,application,scenarios: multirobot transportation and multirobot box pushing.,We then validate,the,ASyMTRe-D implementation,in the multirobot transportation task, illustrating its fault-tolerance capabilities. The advantages,of this new,approach,are that it: 1) enables robots,to synthesize,new,task solutions,using,fundamentally different combinations,of sensors and effectors for different coalition compositions,and,2) provides,a general,mechanism for sharing sensory information across networked,robots. , formation;,information,invariants;","Title: Metrics for quantifying system performance in intelligent, fault-tolerant multi-robot teams\nYear: 2007\n\nAbstract: Any system that has the capability to diagnose and recover from faults is considered to be a fault-tolerant system. Additionally, the quality of the incorporated fault-tolerance has a direct impact on the overall performance of the system. Hence, being able to measure the extent and usefulness of fault- tolerance exhibited by the system would provide the designer with a useful analysis tool for better understanding the system as a whole. Unfortunately, it is difficult to quantify system fault-tolerance on its own for intelligent systems. A more useful metric for evaluation is the \"effectiveness\" measure of fault- tolerance. The influence of fault-tolerance towards improving overall performance determines the overall effectiveness or quality of the system. In this paper, we outline application- independent metrics to measure fault-tolerance within the context of system performance. In addition, we also outline potential methods to better interpret the obtained measures towards understanding the capabilities of the implemented system. Furthermore, a main focus of our approach is to capture the effect of intelligence, reasoning, or learning on the effective fault-tolerance of the system, rather than relying purely on traditional redundancy based measures. We show the utility of the designed metrics by applying them to different fault-tolerance architectures implemented for multiple complex heterogeneous multi-robot team applications and comparing system performance. Finally, we contrast the developed metrics with the only other existing method (HWB method) for evaluating (that we are aware of) effective fault-tolerance for multi-robot teams and rate them in terms of their capability to best interpret the workings of the implemented systems. To the best of our knowledge, this is the first metric that attempts to evaluate the quality of learning towards understanding system level fault-tolerance.","Title: Using critical junctures and environmentally-dependent information for management of tightly-coupled cooperation in heterogeneous robot teams\nYear: 2009\n\nAbstract: This paper addresses the challenge of forming appropriate heterogeneous robot teams to solve tightly-coupled, potentially multi-robot tasks, in which the robot capabilities may vary over the environment in which the task is being performed. Rather than making use of a permanent tightly-coupled robot team for performing the task, our approach aims to recognize when tight coupling is needed, and then only form tight cooperative teams at those times. This results in important cost savings, since coordination is only used when the independent operation of the team members would put mission success at risk. Our approach is to define a new semantic information type, called environmentally dependent information, which allows us to capture certain environmentally-dependent perceptual constraints on vehicle capabilities. We define locations at which the robot team must transition between tight and weak cooperation as critical junctures. Note that these critical juncture points are a function of the robot team capabilities and the environmental characteristics, and are not due to a change in the task itself. We calculate critical juncture points by making use of our prior ASyMTRe approach, which can automatically configure heterogeneous robot team solutions to enable sharing of sensory capabilities across robots. We demonstrate these concepts in experiments involving a human-controlled blimp and an autonomous ground robot in a target localization task.","Title: Fuzzy Temporal Segmentation and Probabilistic Recognition of Continuous Human Daily Activities\nYear: 2015\n\nAbstract: Understanding human activities is an essential capability for intelligent robots to help people in a variety of applications. Humans perform activities in a continuous fashion, and transitions between temporally adjacent activities are gradual. Our Fuzzy Segmentation and Recognition (FuzzySR) algorithm explicitly reasons about gradual transitions between continuous human activities. Our objective is to simultaneously segment a given video into a sequence of events and recognize the activity contained in each event. The algorithm uniformly segments the video into a sequence of nonoverlapping blocks, each lasting a short period of time. Then, a multivariable time series is formed by concatenating block-level human activity summaries that are computed using topic models over local spatiotemporal features extracted from each block. Through encoding an event as a fuzzy set with fuzzy boundaries to represent gradual transitions, our approach is capable of segmenting the continuous visual data into a sequence of fuzzy events. By incorporating all block summaries contained in an event, our algorithm determines the activity label for each event. To evaluate performance, we conduct experiments using six datasets. Our algorithm shows promising continuous activity segmentation results on these datasets and obtains the event-level activity recognition precision of 42.6%, 60.4%, 65.2%, and 78.9% on the Hollywood-2, CAD-60, ACT , and UTK-CAP datasets, respectively.","Title: Cooperative Robotics For Multi-Target Observation\nYear: 1999\n\nAbstract: An important issue that arises in the automation of many security, surveillance and reconnaissance tasks is that of observing (or monitoring) the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement-determining where sensors should be located to maintain the targets in view. In complex applications involving limited-range sensors, the use of multiple sensors dynamically moving over time is required. In this article, we investigate the use of a cooperative team of autonomous sensor-based robots for the observation of multiple moving targets (a problem that we term CMOMMT). We focus primarily on developing the distributed control strategies that allow the robot team to attempt to maximize the collective time during which each target is being observed by at least one robot team member in the area of interest. Our initial efforts on this problem address the aspects of distributed control in robot teams with equivalent movement capabilities working in an uncluttered, bounded area This article first formalizes the problem and discusses related work. We then present a distributed approximate approach to solving this problem (called A-CMOMMT) that combines low-level multi-robot control with higher-level control. The low-level control is described in terms of force fields emanating from the targets and the robots. The higher level control is presented in our ALLANCE formalism[16,17], which provides mechanisms for fault tolerant cooperative control, and allows robot ream members to adjust their low-level actions based upon the actions of their teammates. We then present the results of the ongoing implementation of our approach, both in simulation and on physical robots. To our knowledge, this is the first article addressing this research problem that has been implemented on physical robot teams.","Title: CoDe4D: Color-Depth Local Spatio-Temporal Features for Human Activity Recognition From RGB-D Videos.\nYear: 2016\n\nAbstract: Human activity recognition has a variety of important real-world applications, such as video analysis, surveillance, and human-robot interaction. As a promising video representation method, local spatio-temporal (LST) features have received increasing attention from computer vision, machine learning, and robotics communities. However, approaches based on traditional LST features only use color inf...","Title: Self-Reflective Risk-Aware Artificial Cognitive Modeling for Robot Response to Human Behaviors.\nYear: 2016\n\nAbstract: In order for cooperative robots (\"co-robots\") to respond to human behaviors accurately and efficiently in human-robot collaboration, interpretation of human actions, awareness of new situations, and appropriate decision making are all crucial abilities for co-robots. For this purpose, the human behaviors should be interpreted by co-robots in the same manner as human peers. To address this issue, a novel interpretability indicator is introduced so that robot actions are appropriate to the current human behaviors. In addition, the complete consideration of all potential situations of a robot's environment is nearly impossible in real-world applications, making it difficult for the co-robot to act appropriately and safely in new scenarios. This is true even when the pretrained model is highly accurate in a known situation. For effective and safe teaming with humans, we introduce a new generalizability indicator that allows a co-robot to self-reflect and reason about when an observation falls outside the co-robot's learned model. Based on topic modeling and two novel indicators, we propose a new Self-reflective Risk-aware Artificial Cognitive (SRAC) model. The co-robots are able to consider action risks and identify new situations so that better decisions can be made. Experiments both using real-world datasets and on physical robots suggest that our SRAC model significantly outperforms the traditional methodology and enables better decision making in response to human activities.","Title: Unified robot learning of action labels and motion trajectories from 3D human skeletal data\nYear: 2016\n\nAbstract: Currently, robot learning of human activities is mainly studied in two largely disconnected domains: high level semantics understanding in human activity recognition, and low level motion trajectory reproduction in robot imitation learning. The critical problem of human activity unified learning (HAUL) was not well studied in previous work. One important challenge is the lack of a representation that can be learned from both levels. We introduce a novel approach to address this HAUL problem at the representation level, by simultaneously learning action labels and motion trajectories from publicly available 3D human skeletal datasets, thus avoiding additional human labor for data collection. Our approach builds a subject and body position independent shared skeleton, and extracts features of skeletal activities based on this model. Then the extracted features are encoded by the parameter set of Gaussian Mixture Models to construct the unified representations. The proposed compact representation can be directly applied to identify activity labels when combined with Support Vector Machines, and can be also employed to generate trajectories of the learned activities when combined with Gaussian Mixture Regression on a robot. Finally, an inverse kinematic mapping is developed to transfer human skeletal trajectories to joint angle sequences in the robot's embodiment. Empirical studies using simulation and real humanoid robots demonstrate that our approach achieves promising performance on robot unified learning of human action labels and motion trajectories, effectively addressing the HAUL problem.","Title: Minimum uncertainty latent variable models for robot recognition of sequential human activities.\nYear: 2017\n\nAbstract: Recognition of sequential human activities, such as “sitting down” and “standing up”, is a common but challenging problem in human-robot interaction, which requires modeling their underlying temporal patterns. Although previous sequence modeling methods, such as Hidden Conditional Random Fields (HCRFs), demonstrated satisfactory recognition accuracy, they do not explicitly model the uncertainty in underlying temporal patterns, which can provide valuable information to characterize sequential activities. To address this problem, we introduce a novel Minimum Uncertainty HCRF (MU, or μHCRF). Different from traditional HCRF-based techniques that only utilize the negative log-likelihood of the categoriesu0027 conditional probability as the loss function, the proposed μ-HCRF also introduces a regularization term to model the underlying temporal pattern of the latent variables. As another theoretical contribution, we provide a derivation to show that the formulated problem has a closed-form solution, and prove that inference of the proposed μHCRF is tractable. Extensive empirical study is performed to evaluate our approach, using four public benchmark datasets. Experimental results have shown that our μHCRFs outperform previous techniques and achieve state-of-the-art performance on human activity recognition, especially on sequential activities.","Title: Skeleton-based bio-inspired human activity prediction for real-time human–robot interaction\nYear: 2018\n\nAbstract: Activity prediction is an essential task in practical human-centered robotics applications, such as security, assisted living, etc., which is targeted at inferring ongoing human activities based on incomplete observations. To address this challenging problem, we introduce a novel bio-inspired predictive orientation decomposition (BIPOD) approach to construct representations of people from 3D skeleton trajectories. BIPOD is invariant to scales and viewpoints, runs in real-time on basic computer systems, and is able to recognize and predict activities in an online fashion. Our approach is inspired by biological research in human anatomy. To capture spatio-temporal information of human motions, we spatially decompose 3D human skeleton trajectories and project them onto three anatomical planes (i.e., coronal, transverse and sagittal planes); then, we describe short-term time information of joint motions and encode high-order temporal dependencies. By using Extended Kalman Filters to estimate future skeleton trajectories, we endow our BIPOD representation with the critical capabilities to reduce noisy skeleton observation data and predict the ongoing activities. Experiments on benchmark datasets have shown that our BIPOD representation significantly outperforms previous methods for real-time human activity classification and prediction from 3D skeleton trajectories. Empirical studies using TurtleBot2 and Baxter humanoid robots have also validated that our BIPOD method obtains promising performance, in terms of both accuracy and efficiency, making BIPOD a fast, simple, yet powerful representation for low-latency online activity prediction in human–robot interaction applications.","Title: Creation of the National Artificial Intelligence Research and Development Strategic Plan.\nYear: 2018\n\nAbstract: In October 2016, the United States government published the National Artificial Intelligence Research and Development Strategic Plan, which lays out a strategic plan for federally funded research and development in AI. As a coleader of the task force that developed this plan, I was asked to discuss its creation in an invited presentation at AAAI 2017. This article is based on that presentation, which outlines not only the plan itself, but also provides insight into its goads and objectives, and background into how it was created.","Title: Human Spatio-Temporal Attention Modeling Using Head Pose Tracking for Implicit Object of Interest Discrimination in Robot Agents\nYear: 2018\n\nAbstract: Hazardous search missions are an excellent application domain for human-robot teams because cost-effective robot systems could be leveraged to reduce total mission duration time, improve search space thoroughness, and reduce human exposure to danger. Efficiently pairing robotic agents with human workers requires leveraging implicit communication when explicit techniques are either unavailable, socially unnatural, or impractical, such as is often the case with challenging search and rescue missions. Although successful implicit communication methods for robotics systems exist, (e.g., gestural recognition, activity recognition, and gaze management), a full suite of effective natural communication skills remains an open problem in robotics, thus preventing human-robot team solutions from being more commonplace. To help address this capability gap, we introduce a technique to implicitly model human spatio-temporal attention with a 3D heat map based on head pose trajectory tracking. We then show that this version of attention modeling can be applied by a robot agent to reliably extract Object of Interest (OOI) information for use in improving implicit communication in human-robot teams. This technique is evaluated in an OOI search task and a shared workspace clustered OOI discrimination task.","Title: Robots Can Teach Students With Intellectual Disabilities: Educational Benefits of Using Robotic and Augmented Reality Applications\nYear: 2019\n\nAbstract: In the face of a worldwide teacher shortage and, in the United States, a critical shortage of special education teachers, there is an urgent demand for appropriate educational resources. For people with intellectual and developmental disabilities (I/DDs), in particular, there is a compelling need to develop educational tools and strategies to facilitate independence and self-sufficiency and address poor employment outcomes in adulthood."],"string":"[\n \"Title: Decision making as optimization in multi-robot teams\\nYear: 2012\\n\\nAbstract: A key challenge in multi-robot teaming research is determining how to properly enable robots to make decisions on actions they should take to contribute to the overall system objective. This article discusses how many forms of decision making in multi-robot teams can be formulated as optimization problems. In particular, we examine the common multi-robot capabilities of task allocation, path planning, formation generation, and target tracking/observation, showing how each can be represented as optimization problems. Of course, globally optimal solutions to such formulations are not possible, as it is well-known that such problems are intractable. However, many researchers have successfully built solutions that are approximations to the global problems, which work well in practice. While we do not argue that all decision making in multi-robot systems should be based on optimization formulations, it is instructive to study when this technique is appropriate. Future development of new approximation algorithms to well-known global optimization problems can therefore have an important positive impact for many applications in multi-robot systems.\",\n \"Title: Distributed Cooperative Outdoor Multirobot Localization and Mapping\\nYear: 2004\\n\\nAbstract: The subject of this article is a scheme for distributed outdoor localization of a team of robots and the use of the robot team for outdoor terrain mapping. Localization is accomplished via Extended Kalman Filtering (EKF). In the distributed EKF-based scheme for localization, heterogeneity of the available sensors is exploited in the absence or degradation of absolute sensors aboard the team members. The terrain mapping technique then utilizes localization information to facilitate the fusion of vision-based range information of environmental features with changes in elevation profile across the terrain. The result is a terrain matrix from which a metric map is then generated. The proposed algorithms are implemented using field data obtained from a team of robots traversing an uneven outdoor terrain.\",\n \"Title: Robopedia: Leveraging Sensorpedia for web-enabled robot control\\nYear: 2010\\n\\nAbstract: There is a growing interest in building Internet- scale sensor networks that integrate sensors from around the world into a single unified system. In contrast, robotics applica- tion development has primarily focused on building specialized systems. These specialized systems take scalability and reliabil- ity into consideration, but generally neglect exploring the key components required to build a large scale system. Integrating robotic applications with Internet-scale sensor networks will unify specialized robotics applications and provide answers to large scale implementation concerns. We focus on utilizing Internet-scale sensor network technology to construct a frame- work for unifying robotic systems. Our framework web-enables a surveillance robot's sensor observations and provides a web- interface to the robot's actuators. This lets robots seamlessly integrate into web applications. In addition, the framework eliminates most prerequisite robotics knowledge, allowing for the creation of general web-based robotics applications. The framework also provides mechanisms to create applications that can interface with any robot. Frameworks such as this one are key to solving large scale mobile robotics implemen- tation problems. We provide an overview of previous Internet- scale sensor networks, Sensorpedia (an ad-hoc Internet-scale sensor network), our framework for integrating robots with Sensorpedia, two applications which illustrate our frameworks ability to support general web-based robotic control, and offer experimental results that illustrate our framework's scalability, feasibility, and resource requirements. I. INTRODUCTION\",\n \"Title: Tightly-Coupled Navigation Assistance in Heterogeneous Multi-Robot Teams\\nYear: 2004\\n\\nAbstract: This paper presents the design and results of autonomous behaviors for tightly-coupled cooperation in het- erogeneous robot teams, specifically for the task of navigat ion assistance. These cooperative behaviors enable capable, sensor- rich (\\\"leader\\\") robots to assist in the navigation of sensor-limited (\\\"simple\\\") robots that have no onboard capabilities for obstacle avoidance or localization, and only minimal capabilities for kin recognition. The simple robots must be dispersed throughout a known, indoor environment to serve as a sensor network. However, because of their navigation limitations, they are unable to autonomously disperse themselves or move to planned sensor deployment positions independently. To address this challenge, we present cooperative behaviors for heterogeneous robots that enable the successful deployment of sensor-limited robots by assistance from more capable leader robots. These heteroge- neous cooperative behaviors are quite complex, and involve the combination of several behavior components, including vision- based marker detection, autonomous teleoperation, color marker following in robot chains, laser-based localization, map-based path planning, and ad hoc mobile networking. We present the results of the implementation and extensive testing of these behaviors for deployment in a rigorous test environment. To our knowledge, this is the most complex heterogeneous robot team cooperative task ever attempted on physical robots. We consider it a significant success to have achieved such a high degree of system effectiveness, given the complexity of the overall heterogeneous system.\",\n \"Title: ASyMTRe: Automated Synthesis of Multi-Robot Task Solutions through Software Reconfiguration\\nYear: 2005\\n\\nAbstract: This paper describes a methodology for automat ically synthesizing task solutions for heterogeneous multi-robot teams. In contrast to prior approaches that require a manual pre definition of how the robot team will accomplish its task (while perhaps automating who performs which task), our approach automates both the how and the who to generate task solution approaches that were not explicitly defined by the designer a priori. The advantages of this new approach are that it: (1) enables the robot team to synthesize new task solutions that use fundamentally different combinations of robot behaviors for different team compositions, and (2) provides a general mechanism for sharing sensory information across networked robots, so that more capable robots can assist less capable robots in accomplishing their objectives. Our approach, which we call ASyMTRe (Automated Synthesis of Multi-robot Task solutions through software Reconfiguration, pronounced “Asymmetry”), is based on mapping environmental, perceptual, and motor control schemas to the required flow of information through the multi-robot system, automatically reconfiguring the connections of schemas within and across robots to synthesize valid and efficient multi-robot behaviors for accomplishing the team objectives. We validate this approach by presenting the results of applying our methodology to two different teaming scenarios: altruistic cooperation involving multi-robot transportation, and coalescent cooperation involving multi-robot box pushing.\",\n \"Title: Designing Control Laws for Cooperative Agent Teams\\nYear: 1993\\n\\nAbstract: The design of the control laws governing the behavior of individual agents is crucial for the successful development of cooperative agent teams. These control laws utilize a combination of local and/or global knowledge to achieve the resulting group behavior. A key difficulty in this development is determining the appropriate balance between the use of global information and the use of local information to achieve coherent cooperation without excessive communication requirements. This paper...\",\n \"Title: Multi-robot task scheduling\\nYear: 2013\\n\\nAbstract: The scheduling problem has been studied extensively in the literature. Many algorithms have been developed to operate with different types of processors and tasks. In the robotics domain, when considering each robot as a processor, some of these algorithms can be directly adapted. However, most of the existing algorithms can only handle single-robot tasks, or multi-robot tasks that can be divided into single-robot tasks. As the task requirements may only be partially known, and the available (heterogeneous) robots can dynamically change, robots may be required to cooperate tightly to share different capabilities (i.e., sensors and motors). In such cases, considering scheduling for individual robots is no longer sufficient, since the robots need to work at the coalition level. Although there exist a few algorithms that also support these more complex cases, they do not represent efficient solutions that can be adapted by various multi-robot systems in a convenient manner. In this paper, we propose heuristics to address the multi-robot task scheduling problem at the coalition level, which hides the details of robot specifications, thus allowing these heuristics to be incorporated straightforwardly. These heuristics are easy to implement and efficient enough to run in real time. We provide formal analyses and simulation results to demonstrate and compare their performances.\",\n \"Title: Zebrafish Larva Locomotor Activity Analysis Using Machine Learning Techniques\\nYear: 2013\\n\\nAbstract: Zebra fish larvae have become a popular model organism to investigate genetic and environmental factors affecting behavior. However, difficulties exist in the analysis of complex behaviors from a large array of larvae. In this paper, we present the new application of machine learning techniques in bioinformatics to automatically detect and investigate the locomotor activities of zebra fish larvae. To achieve this, twelve features were defined and seven unsupervised learning methods were implemented. Next, seven performance measures were applied to evaluate and compare these methods. In order to empirically evaluate the machine learning algorithms, a large dataset was collected that contained 6847 valid instances. Using this dataset, the characteristics of the features were analyzed and the most appropriate unsupervised learning algorithm, i.e., Unweighted Pair Group Method with Arithmetic mean (UPGMA), for locomotor activity analysis was identified. In addition, UPGMA's ability to reveal underlying patterns of zebra fish locomotor activities was demonstrated. In general, this study shows that machine learning techniques have the potential to construct effective, high-throughput systems to automate the process of identifying zebra fish behaviors influenced by genetic manipulation, pharmaceuticals, and environmental toxins.\",\n \"Title: Distributed sensor analysis for fault detection in tightly-coupled multi-robot team tasks\\nYear: 2009\\n\\nAbstract: This paper presents a distributed version of our previous work, called SAFDetection, which is a sensor analysis-based fault detection approach that is used to monitor tightly-coupled multi-robot team tasks.While the centralized version of SAFDetection was shown to be successful, a shortcoming of the approach is that it does not scale well to large team sizes. The distributed SAFDetection approach addresses this problem by adapting and distributing the approach across team members. Distributed SAFDetection has the same theoretic foundation as centralized SAFDetection, which maps selected robot sensor data to a robot state by using a clustering algorithm, and builds state transition diagrams to describe the normal behavior of the robot system. However, rather than processing multiple robots' sensor data centralized on a server, distributed SAFDetection performs feature selection and clustering on individual robots to build the normal behavior model of an individual robot and the entire robot team. Fault detection is also accomplished in a distributed manner. We have implemented this distributed approach on a physical robot team and in simulation. This paper presents the results of these experiments, showing that distributed SAFDetection is an efficient approach to detect both local and interactive faults in tightly-coupled multi-robot team tasks. Compared to the centralized version, this approach provides more scalability and reliability.\",\n \"Title: A Complete Methodology for Generating Multi-Robot Task Solutions using ASyMTRe-D and Market-Based Task Allocation\\nYear: 2007\\n\\nAbstract: This paper presents an approach that enables heterogeneous robots to automatically form groups as needed to generate both strongly-cooperative and weakly-cooperative multi-robot task solutions in the same application. The fundamental contribution of this work is the layering of our low-level coalition formation algorithm for generating strongly-cooperative task solutions, with high-level, traditional task allocation methods for weakly-cooperative task solutions. At the low level, coalitions that generate strongly-cooperative multi-robot task solutions are formed using our ASyMTRe-D approach that maps environmental sensors and perceptual and motor schemas to the required flow of information in the robot team, automatically reconfiguring the connections of schemas within and across robots to form efficient solutions. At the high level, a traditional task allocation approach is used to enable individual robots and/or coalitions to compete for weakly-cooperative task assignments through task allocation. We introduce the site clearing task to motivate the work, and then formalize the problem. We then present the approach of layering ASyMTRe-D with task allocation. We validate the approach on a team of robots with the site clearing task. We believe the resulting approach is a flexible system that can handle a broad range of realistic multi-robot applications beyond what is possible using other existing approaches.\",\n \"Title: Sensor Analysis For Fault Detection In Tightly-Coupled Multi-Robot Team Tasks\\nYear: 2007\\n\\nAbstract: This paper presents a sensor analysis based fault detection approach (which we call SAFDetection) that is used to monitor tightly-coupled multi-robot team tasks. Our approach aims at detecting both physical and logic faults of a robot system with little prior knowledge on the system. We do not need the motion model or a priori knowledge of the possible fault types of the monitored system. Our approach treats the monitored robot system as a black box, with only sensor data available. Thus, we believe the approach is general, and can be used in a wide variety of robot systems performing many different kinds of tasks. Our approach combines data clustering techniques with the generation of a probabilistic state diagram to model the normal operation of the multi-robot system. We have implemented this approach on a physical robot team. This paper presents the results of these experiments, which show that sensor data analyzed from a training phase of normal operation can be used to generate a model of normal robot team operation. This model can then be used to detect many types of abnormal behavior of the system, based purely on monitoring the sensor data of the system.\",\n \"Title: IQ-ASyMTRe: Forming Executable Coalitions for Tightly Coupled Multirobot Tasks\\nYear: 2013\\n\\nAbstract: While most previous research on forming coalitions mainly concentrates on loosely coupled multirobot tasks, a more challenging problem is to address tightly coupled multirobot tasks that involve close robot coordinations, which often require capability sharing. General methods for autonomous capability sharing have been shown to greatly improve the flexibility of distributed systems. However, in addition to the interaction constraints between the robots and the environment as required by the tasks, these methods may introduce additional interaction constraints between the robots based on how the capabilities are shared. The satisfiability of these constraints in the current situation determines the feasibility of the potential coalitions. To achieve system autonomy, the ability to identify the potential coalitions that are feasible for task execution is critical. In this paper, we demonstrate a general approach that incorporates this capability based on the ASyMTRe architecture. The extended architecture, which is called IQ-ASyMTRe, is able to find coalitions in which these required constraints are satisfied. When used to form coalitions, IQ-ASyMTRe sets up only feasible coalitions, thus enabling tasks to be executed autonomously. We formally present the new architecture and prove that it is sound and complete, given certain assumptions. Simulations and experimental results are provided for different applications in which the robots are able to flexibly form coalitions that are ready to execute.\",\n \"Title: Approximate l-Fold Cross-Validation with Least Squares SVM and Kernel Ridge Regression\\nYear: 2013\\n\\nAbstract: Kernel methods have difficulties scaling to large modern data sets. The scalability issues are based on computational and memory requirements for working with a large matrix. These requirements have been addressed over the years by using low-rank kernel approximations or by improving the solvers' scalability. However, Least Squares Support Vector Machines (LS-SVM), a popular SVM variant, and Kernel Ridge Regression still have several scalability issues. In particular, the O(n^3) computational complexity for solving a single model, and the overall computational complexity associated with tuning hyper parameters are still major problems. We address these problems by introducing an O(nlog n) approximate l-fold cross-validation method that uses a multi-level circulant matrix to approximate the kernel. In addition, we prove our algorithm's computational complexity and present empirical runtimes on data sets with approximately one million data points. We also validate our approximate method's effectiveness at selecting hyper parameters on real world and standard benchmark data sets. Lastly, we provide experimental results on using a multi level circulant kernel approximation to solve LS-SVM problems with hyper parameters selected using our method.\",\n \"Title: Considering inter-task resource constraints in task allocation\\nYear: 2013\\n\\nAbstract: This paper focuses on task allocation with single-task robots, multi-robot tasks and instantaneous assignment, which has been shown to be strongly NP-hard. Although this problem has been studied extensively, few efficient approximation algorithms have been provided due to its inherent complexity. In this paper, we first provide discussions and analyses for two natural greedy heuristics for solving this problem. Then, a new greedy heuristic is introduced, which considers inter-task resource constraints to approximate the influence between different assignments in task allocation. Instead of only looking at the utility of the assignment, our approach computes the expected loss of utility (due to the assigned robots and task) as an offset and uses the offset utility for making the greedy choice. A formal analysis is provided for the new heuristic, which reveals that the solution quality is bounded by two different factors. A new algorithm is then provided to approximate the new heuristic for performance improvement. Finally, for more complicated applications, we extend this problem to include general task dependencies and provide a result on the hardness of approximating this new formulation. Comparison results with the two natural heuristics in simulation are provided for both formulations, which show that the new approach achieves improved performance.\",\n \"Title: Task allocation with executable coalitions in multirobot tasks\\nYear: 2012\\n\\nAbstract: In our prior work, we proposed the IQ-ASyMTRe architecture with a measure of information quality to reason about forming coalitions in multirobot tasks. The formed coalitions are guaranteed to be executable, given the current configurations of the robots and environment. A cost and a quality measure are associated with each coalition to further determine its utility for the task. In this paper, we show that IQ-ASyMTRe-like architectures can be utilized to significantly reduce the overall complexity of task allocation by considering only executable coalitions. For implementation, we apply a layering technique such that most existing methods for task allocation can be easily incorporated. Furthermore, we introduce a general process to address situations in which no executable coalitions are available for certain tasks, and integrate it with IQ-ASyMTRe to achieve more autonomy. Such an approach is able to autonomously decompose unsatisfied preconditions of the required task behaviors into satisfiable components, in order to generate partial order plans for them accordingly. We show how this process can be implemented using a market-based approach. Simulation results are provided to demonstrate these techniques.\",\n \"Title: Experiments with a Large Heterogeneous Mobile Robot Team: Exploration, Mapping, Deployment and Detection\\nYear: 2006\\n\\nAbstract: We describe the design and experimental validation of a large heterogeneous mobile robot team built for the DARPA Software for Distributed Robotics (SDR) program. The core challenge for the SDR program was to develop a multi-robot system capable of carrying out a specific mission: to deploy a large number of robots into an unexplored building, map the building interior, detect and track intruders, and transmit all of the above information to a remote operator. To satisfy these requirements, we developed a heterogeneous robot team consisting of approximately 80 robots. We sketch the key technical elements of this team, focusing on the novel aspects, and present selected results from supervised experiments conducted in a 600 m 2 indoor environment.\",\n \"Title: Detecting time-related changes in Wireless Sensor Networks using symbol compression and Probabilistic Suffix Trees\\nYear: 2010\\n\\nAbstract: Our research focuses on anomaly detection problems in unknown environments using Wireless Sensor Networks (WSN). We are interested in detecting two types of abnormal events: sensory level anomalies (e.g., noise in an office without lights on) and time-related anomalies (e.g., freezing temperature in a mid-summer day).We present a novel, distributed, machine learning based anomaly detector that is able to detect time-related changes. It consists of three components. First, a Fuzzy Adaptive Resonance Theory (ART) neural network classifier is used to label multi-dimensional sensor data into discrete classes and detect sensory level anomalies. Over time, the labeled classes form a sequence of classes. Next, a symbol compressor is used to extract the semantic meaning of the temporal sequence. Finally, a Variable Memory Markov (VMM) model in the form of a Probabilistic Suffix Tree (PST) is used to model and detect time-related anomalies in the environment. To our knowledge, this is the first work that analyzes/models the temporal sensor data using a symbol compressor and PST in a WSN. Our proposed detection algorithm is distributed, “light-weight”, and practical for resource constrained sensor nodes. We verify the proposed approach using a volcano monitoring dataset. Our results show that this approach yields the same performance as the traditional Markov models with much less cost.\",\n \"Title: Quantitative and Qualitative Comparison of Three Laser-Range Mapping Algorithms Using Two Types of Laser Scanner Data\\nYear: 2000\\n\\nAbstract: This paper presents our initial results in comparing three algorithms for autonomous robotic mapping using two types of laser scanner data. The algorithms compared are the Markov localization approach of Thrun, the Lu and Milios iterative dual correspondence algorithm, and the Touzet model-free landmark extraction algorithm. The two types of laser scanner data utilized are the AccuRange laser scanner from Acuity and the SICK laser scanner. We compare these algorithms in terms of the quality of mapped results, computational requirements, and sensitivity to data and odometry error. While the complete comparison of these algorithms on all these measures is not yet accomplished; our results to date indicate that laser mapping algorithms are not immediately transferrable from one type of laser scanner data to another. Instead, algorithms appear to make implicit assumptions on the quality or content of laser data that play a strong role in the quality of the mapping results.\",\n \"Title: Multi-Robot Team Design for Real-World Applications.\\nYear: 1996\\n\\nAbstract: Real-world applications that are ideal for robotic solutions are very complex and challenging. Manyof these applications are set in dynamic environments that require capabilities distributed in functionality,space, or time. These applications, therefore, often require teams of robots to work togethercooperatively to successfully address the mission. While much research in recent years has addressedthe issues of autonomous robots and multi-robot cooperation, current robotics technology is...\",\n \"Title: Distributed Algorithms for Multi-Robot Observation of Multiple Moving Targets\\nYear: 2002\\n\\nAbstract: An important issue that arises in the automation of many security, surveillance, and reconnaissance tasks is that of observing the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement—determining where sensors should be located to maintain the targets in view. In complex applications involving limited-range sensors, the use of multiple sensors dynamically moving over time is required. In this paper, we investigate the use of a cooperative team of autonomous sensor-based robots for the observation of multiple moving targets. In other research, analytical techniques have been developed for solving this problem in complex geometrical environments. However, these previous approaches are very computationally expensive—at least exponential in the number of robots—and cannot be implemented on robots operating in real-time. Thus, this paper reports on our studies of a simpler problem involving uncluttered environments—those with either no obstacles or with randomly distributed simple convex obstacles. We focus primarily on developing the on-line distributed control strategies that allow the robot team to attempt to minimize the total time in which targets escape observation by some robot team member in the area of interest. This paper first formalizes the problem (which we term CMOMMT for iCooperative Multi-Robot Observation of Multiple Moving Targets) and discusses related work. We then present a distributed heuristic approach (which we call A-CMOMMT) for solving the CMOMMT problem that uses weighted local force vector control. We analyze the effectiveness of the resulting weighted force vector approach by comparing it to three other approaches. We present the results of our experiments in both simulation and on physical robots that demonstrate the superiority of the A-CMOMMT approach for situations in which the ratio of targets to robots is greater than 1/2. Finally, we conclude by proposing that the CMOMMT problem makes an excellent domain for studying multi-robot learning in inherently cooperative tasks. This approach is the first of its kind for solving the on-line cooperative observation problem and implementing it on a physical robot team.\",\n \"Title: Real-time multiple human perception with color-depth cameras on a mobile robot.\\nYear: 2013\\n\\nAbstract: The ability to perceive humans is an essential requirement for safe and efficient human-robot interaction. In real-world applications, the need for a robot to interact in real time with multiple humans in a dynamic, 3-D environment presents a significant challenge. The recent availability of commercial color-depth cameras allow for the creation of a system that makes use of the depth dimension, thus enabling a robot to observe its environment and perceive in the 3-D space. Here we present a system for 3-D multiple human perception in real time from a moving robot equipped with a color-depth camera and a consumer-grade computer. Our approach reduces computation time to achieve real-time performance through a unique combination of new ideas and established techniques. We remove the ground and ceiling planes from the 3-D point cloud input to separate candidate point clusters. We introduce the novel information concept, depth of interest, which we use to identify candidates for detection, and that avoids the computationally expensive scanning-window methods of other approaches. We utilize a cascade of detectors to distinguish humans from objects, in which we make intelligent reuse of intermediary features in successive detectors to improve computation. Because of the high computational cost of some methods, we represent our candidate tracking algorithm with a decision directed acyclic graph, which allows us to use the most computationally intense techniques only where necessary. We detail the successful implementation of our novel approach on a mobile robot and examine its performance in scenarios with real-world challenges, including occlusion, robot motion, nonupright humans, humans leaving and reentering the field of view (i.e., the reidentification challenge), human-object and human-human interaction. We conclude with the observation that the incorporation of the depth information, together with the use of modern techniques in new ways, we are able to create an accurate system for real-time 3-D perception of humans by a mobile robot.\",\n \"Title: Cooperative multi-robot observation of multiple moving targets\\nYear: 1997\\n\\nAbstract: An important issue that arises in the automation of many security, surveillance, and reconnaissance tasks is that of monitoring, or observing, the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement-determining where sensors should be located to maintain the targets in view. In complex applications of this type, the use of multiple sensors dynamically moving over time is required. In this paper, we investigate the use of a cooperative team of autonomous sensor-based robots for multi-robot observation of multiple moving targets. We focus primarily on developing the distributed control strategies that allow the robot team to attempt to maximize the collective time during which each object is being observed by at least one robot in the area of interest. Our initial efforts in this problem address the aspects of distributed control in homogeneous robot teams with equivalent sensing and movement capabilities working in an uncluttered, bounded area. This paper first formalizes the problem, discusses related work, and then shows that this problem is NP-hard. We then present a distributed approximate approach to solving this problem that combines low-level multi-robot control with higher-level control. The low-level control is described in terms of force fields emanating from the targets and the robots. The higher level control is presented in the ALLIANCE formalism, which provides mechanisms for fault tolerant cooperative control, and allows robot team members to adjust their low-level actions based upon the actions of their teammates. We then present the results of the implementation of portions of our approach, both in simulation and on physical robots.\",\n \"Title: On the design of behavior-based multi-robot teams\\nYear: 1995\\n\\nAbstract: Real-world applications that are ideal for robotic solutions are very complex and challenging. Many of these applications are set in dynamic environments that require capabilities distributed in functionality, space or time. These applications, therefore, often require teams of robots to work together cooperatively to successfully address the mission. While much research in recent years has addressed the issues of autonomous robots and multi-robot cooperation, current robotics technology is still far from achieving many of these real world applications. We believe that two primary reasons for this technology gap are that (1) previous work has not adequately addressed the issues of fault tolerance and adaptivity in multi-robot teams, and (2) existing robotics research is often geared at specific applications and is not easily generalized to different, but related, applications. This paper addresses these issues by first describing the design issues of key importance in these real-world cooperative robotics applications - fault tolerance, reliability, adaptivity and coherence. We then present a general architecture addressing these design issues - called ALLIANCE - that facilitates multi-robot cooperation of small- to medium-sized teams in dynamic environments, performing missions composed of loosely coupled subtasks. We illustrate the generality of this architecture by describing two very different proof-of-concept implementations of this architecture: a janitorial service mission and a bounding overwatch mission.\",\n \"Title: Adaptive heterogeneous multi-robot teams\\nYear: 1999\\n\\nAbstract: This research addresses the problem of achieving fault-tolerant cooperation within small- to medium-sized teams of heterogeneous mobile robots. We describe a novel behavior-based, fully distributed architecture, called ALLIANCE, that utilizes adaptive action selection to achieve fault tolerant cooperative control in robot missions involving loosely coupled tasks. The robots in this architecture possess a variety of high-level functions that they can perform during a mission, and must at all times select an appropriate action based on the requirements of the mission, the activities of other robots, the current environmental conditions, and their own internal states. Since such cooperative teams often work in dynamic and unpredictable environments, the software architecture allows the team members to respond robustly and reliably to unexpected environmental changes and modifications in the robot team that may occur due to mechanical failure, the learning of new skills, or the addition or removal of robots from the team by human intervention. After presenting ALLIANCE, we describe in detail our experimental results of an implementation of this architecture on a team of physical mobile robots performing a cooperative box pushing demonstration. These experiments illustrate the ability of ALLIANCE to achieve adaptive, fault-tolerant cooperative control amidst dynamic changes in the capabilities of the robot team.\",\n \"Title: Peer-to-Peer Human-Robot Teaming through Reconfigurable Schemas\\nYear: 2006\\n\\nAbstract: This position paper presents our ongoing work of developing mechanisms to facilitate human-robot teaming with a focus on peer-to-peer interaction. We have developed an approach that autonomously configures solutions for multi-robot teams based on the team capabilities and the task objective. With the success of this approach in simulation and on physical robots, we plan to extend it to address several challenging issues in human-robot teaming. a dialogue system to facilitate the interaction; computational cognitive architectures that model humans to enhance the understanding between humans and robots; and a series of evaluation methods. This project is currently the most com- prehensive work that deals with most of the issues in human- robot teaming. The objective of our work is to explore an alternative way of interaction based on the information that team members need to exchange to accomplish the task col- laboratively.\",\n \"Title: Lifelong Adaptation in Heterogeneous Multi-Robot Teams: Response to Continual Variation in Individual Robot Performance\\nYear: 2000\\n\\nAbstract: Generating teams of robots that are able to perform their tasks over long periods of time requires the robots to be responsive to continual changes in robot team member capabilities and to changes in the state of the environment and mission. In this article, we describe the L-ALLIANCE architecture, which enables teams of heterogeneous robots to dynamically adapt their actions over time. This architecture, which is an extension of our earlier work on ALLIANCE, is a distributed, behavior-based architecture aimed for use in applications consisting of a collection of independent tasks. The key issue addressed in L-ALLIANCE is the determination of which tasks robots should select to perform during their mission, even when multiple robots with heterogeneous, continually changing capabilities are present on the team. In this approach, robots monitor the performance of their teammates performing common tasks, and evaluate their performance based upon the time of task completion. Robots then use this information throughout the lifetime of their mission to automatically update their control parameters. After describing the L-ALLIANCE architecture, we discuss the results of implementing this approach on a physical team of heterogeneous robots performing proof-of-concept box pushing experiments. The results illustrate the ability of L-ALLIANCE to enable lifelong adaptation of heterogeneous robot teams to continuing changes in the robot team member capabilities and in the environment.\",\n \"Title: Behavior-Based Cooperative Robotics Applied to Multi-Target Observation\\nYear: 1996\\n\\nAbstract: this paper, we investigate the useof a cooperative team of autonomous sensor-based robots for the observation of multiplemoving targets. We focus primarily on developing the distributed control strategies thatallow the robot team to attempt to minimize the total time in which targets escapeobservation by some robot team member in the area of interest. Our initial efforts onthis problem address the aspects of distributed control in homogeneous robot teams withequivalent sensing and...\",\n \"Title: Heterogeneous Mobile Sensor Net Deployment Using Robot Herding And Line-Of-Sight Formations\\nYear: 2003\\n\\nAbstract: This paper presents an approach for deploying a team of mobile sensor nodes to form a sensor network in indoor environments. The challenge in this work is that the mobile sensor nodes have no ability for localization or obstacle avoidance. Thus, our approach entails the use of more capable \\\"helper\\\" robots that \\\"herd\\\" the mobile sensor nodes into their deployment positions. To extensively explore the issues of heterogeneity in multi-robot teams, we employ the use of two types of helper robots - one that acts as a leader and a second that: 1) acts as a follower and 2) autonomously teleoperates the mobile sensor nodes. Due to limited sensing capabilities, neither of these helper robots can herd the mobile sensor nodes alone; instead, our approach enables the team as a whole to successfully accomplish the sensor deployment task. Our approach involves the use of line-of-sight formation keeping, which enables the follower robot to use visual markers to move the group along the path executed by the leader robot We present results of the implementation of this approach in simulation, as well as results to date in the implementation on physical robot systems. To our knowledge, this is the first implementation of robot herding using such highly heterogeneous robots, in which no single type of robot could accomplish the sensor network deployment task, even if multiple copies of that robot type were available.\",\n \"Title: A general information quality based approach for satisfying sensor constraints in multirobot tasks\\nYear: 2010\\n\\nAbstract: Many architectures have been proposed to solve tightly-coupled multirobot tasks (MT) through coalitions of heterogeneous robots. However, several issues remain unaddressed. As coalitions are formed, sensor constraints among robots are also established. For example, in a leader-follower task, follower robots must keep leader robots within their sights, while in a box-pushing task, a supervisor robot needs to track the moving direction of the box and monitor the pushing path to the goal for obstacle avoidance. The question of how to keep these constraints satisfied during the entire execution, from initial configurations to completeness of the task, remains an open issue. In addition, environmental factors, both static and dynamic, can influence the maintenance of the constraints. Moreover, problems arise when the constraints are unsatisfiable given the current circumstances. For example, the sight of the leader might be blocked or there might be obstacles blocking the view of the box. This paper proposes a general method to address these issues for various applications with sensors having certain characteristics. Our approach combines the use of sensor models, environment sampling, measures of information quality, a motion model with sampling, and a constraint model. We believe that this approach offers the first generic formulation of robotic sensor constraints that can be applied to a wide variety of applications. To illustrate this method, we apply the approach to solve robot tracking and navigation tasks both in simulation and with physical robots. Experimental results illustrate the flexibility and robustness of the approach.\",\n \"Title: A Decentralized Architecture for Multi-Robot Systems Based on the Null-Space-Behavioral Control with Application to Multi-Robot Border Patrolling.\\nYear: 2013\\n\\nAbstract: This paper presents a control architecture for multi-robot systems. The proposed architecture has been developed in the framework of the Null-Space-based-Behavioral (NSB) control, a competitive-collaborative behavior-based control approach. The standard NSB statically determines a set of suitably defined elementary tasks (behaviors) and their priorities, i.e., they cannot be dynamically changed according to mission requirements and environmental constraints. In this paper, a three layer architecture has been designed in order to avoid such a drawback. The single robotic unit (agent) performing the mission is placed on the lower layer. In the middle layer, suitably defined elementary are defined; these elementary are then combined, via the NSB approach, in more complex . The upper layer is a Supervisor in charge of dynamically selecting the proper action to be executed. As further contribution, the architecture has been applied to the multi-robot border patrolling mission to generate a decentralized, deterministic and non-communicative solution that is robust to faults, and prevents collisions, even in the case of high robot density. Finally, the simulations on a team composed by a large number of robots, and experiments on a real setup, composed by three Pioneer-3DX robots, are provided.\",\n \"Title: Adaptive Causal Models For Fault Diagnosis, And Recovery In Multi-Robot Teams\\nYear: 2006\\n\\nAbstract: This paper presents an adaptive causal model method (adaptive CMM) for fault diagnosis and recovery in complex multi-robot teams. We claim that a causal model approach is effective for anticipating and recovering from many types of robot team errors, presenting extensive experimental results to support this claim. To our knowledge, these results show the first, full implementation of a CMM on a large multi-robot team. However, because of the significant number of possible failure modes in a complex multi-robot application, and the difficulty in anticipating all possible failures in advance, our empirical results show that one cannot guarantee the generation of a complete a priori causal model that identifies and specifies all faults that may occur in the system. Instead, an adaptive method is needed to enable the robot team to use its experience to update and extend its causal model to enable the team, over time, to better recover from faults when they occur. We present our case-based learning approach, called LeaF (for Learning-based Fault diagnosis), that enables robot team members to adapt their causal models, thereby improving their ability to diagnose and recover from these faults over time.\",\n \"Title: Distributed Intelligence: Overview of the Field and its Application in Multi-Robot Systems\\nYear: 2007\\n\\nAbstract: This paper introduces the concepts of distributed intelligence, outlining the motivations for studying this field of research. We then classify common systems of distributed intelligence based upon the types of interactions exhibited, since the type of interaction has relevance to the solution paradigm to be used. We outline three common paradigms for distributed intelligence — the bioinspired paradigm, the organizational and social paradigm, and the knowledge-based, ontological paradigm — and give examples of how these paradigms can be used in multi-robot systems. We then look at a common problem in multi-robot systems — that of task allocation — and show how the solution approach to this problem is very different depending upon the paradigm chosen for abstract- ing the problem. Our conclusion is that the paradigms are not interchangeable, but rather the selection of the appropri- ate paradigm is dependent upon the specific constraints and requirements of the application of interest. Further work is needed to provide guidance to the system designer on select- ing the proper abstraction, or paradigm, for a given problem.\",\n \"Title: A Reinforcement Learning Algorithm in Cooperative Multi-Robot Domains\\nYear: 2005\\n\\nAbstract: Reinforcement learning has been widely applied to solve a diverse set of learning tasks, from board games to robot behaviours. In some of them, results have been very successful, but some tasks present several characteristics that make the application of reinforcement learning harder to define. One of these areas is multi-robot learning, which has two important problems. The first is credit assignment, or how to define the reinforcement signal to each robot belonging to a cooperative team depending on the results achieved by the whole team. The second one is working with large domains, where the amount of data can be large and different in each moment of a learning step. This paper studies both issues in a multi-robot environment, showing that introducing domain knowledge and machine learning algorithms can be combined to achieve successful cooperative behaviours.\",\n \"Title: Distributed Multi-Agent Diagnosis And Recovery From Sensor Failures\\nYear: 2003\\n\\nAbstract: This paper presents work extending previous research in sensor fault tolerance, classification, and recovery from a single robot to a heterogeneous team of distributed robots. This approach allows teams of robots to share knowledge about the working environment, sensor and task state, to diagnose failures and also communicate to redistribute tasks in the event that a robot becomes inoperable. Our work presents several novel extensions to prior art: distributed fault handling and task management in a dynamic, distributed Java framework. This research was implemented and demonstrated on robots in a lab environment performing a simplified search operation.\",\n \"Title: IQ-ASyMTRe: Synthesizing coalition formation and execution for tightly-coupled multirobot tasks\\nYear: 2010\\n\\nAbstract: This paper presents the IQ-ASyMTRe architecture, which is aimed to address both coalition formation and execution for tightly-coupled multirobot tasks in a single framework. Many task allocation algorithms have been previously proposed without explicitly enabling the sharing of robot capabilities. Inspired by information invariant theory, ASyMTRe was introduced which enables the sharing of sensory and computational capabilities by allowing information to flow among different robots via communication. However, ASyMTRe does not provide a solution for how a coalition should satisfy sensor constraints introduced by the sharing of capabilities while executing the assigned task. Furthermore, conversions among different information types are hardcoded, which limits the flexibility of ASyMTRe. Moreover, relationships between entities (e.g., robots) and information types are not explicitly captured, which may produce infeasible solutions from the start, as the defined information type may not correspond well to the current environment settings. The new architecture introduces a complete definition of information type to guarantee the feasibility of solutions; it also explicitly models information conversions. Inspired by our previous work, IQ-ASyMTRe uses measures of information quality to guide robot coalitions to satisfy sensor constraints (introduced by capability sharing) while executing tasks, thus providing a complete and general solution. We demonstrate the capability of the approach both in simulation and on physical robots to form and execute coalitions that share sensory information to achieve tightly-coupled tasks.\",\n \"Title: Estimating building simulation parameters via Bayesian structure learning\\nYear: 2013\\n\\nAbstract: Many key building design policies are made using sophisticated computer simulations such as EnergyPlus (E+), the DOE flagship whole-building energy simulation engine. E+ and other sophisticated computer simulations have several major problems. The two main issues are 1) gaps between the simulation model and the actual structure, and 2) limitations of the modeling engine's capabilities. Currently, these problems are addressed by having an engineer manually calibrate simulation parameters to real world data or using algorithmic optimization methods to adjust the building parameters. However, some simulations engines, like E+, are computationally expensive, which makes repeatedly evaluating the simulation engine costly. This work explores addressing this issue by automatically discovering the simulation's internal input and output dependencies from ~20 Gigabytes of E+ simulation data, future extensions will use ~200 Terabytes of E+ simulation data. The model is validated by inferring building parameters for E+ simulations with ground truth building parameters. Our results indicate that the model accurately represents parameter means with some deviation from the means, but does not support inferring parameter values that exist on the distribution's tail.\",\n \"Title: On the design and development of a human-robot synergistic system\\nYear: 1992\\n\\nAbstract: A great variety of robotic systems have been developed over the past decades, varying from fully human-controlled teleoperated systems, to fully motion-programmed, industrial-type devices, to sensor-equipped ‘intelligent’ machines with autonomous perception and reasoning capabilities. All these systems, however, have very static roles in supporting humans, in the sense that their capabilities are limited to very narrow functions or tasks domains and they cannot really adapt to changing environments where entirely new tasks may be necessary. By considering these systems as part of overall human-machine systems, interesting adaptation capabilities can be envisioned for the machine through the sharing of control and experiences, and observation of the human actions. This paper proposes a general conceptual architecture for enhancing the synergy between humans and machines in such cooperative systems, and investigates an implementation of the concept to the synergistic integration of teleoperative and autonomous operation of a manipulator arm for the execution of sequential tasks. The proposed architecture reflects a unique blend of many disciplines of artificial or machine intelligence and the functioning of its major modules is discussed. The paper then focuses on initial implementations of the Job Planner, Task Allocator, and Execution Monitor modules to discuss simple proof-of-principle experiments illustrating the coalescence of these modules needed to achieve skill-based dynamic task planning, allocation, and execution.\",\n \"Title: Evaluating success in autonomous multi-robot teams: experiences from ALLIANCE architecture implementations\\nYear: 2001\\n\\nAbstract: A current limitation in multi-robot systems research is the lack of metrics that enable the performance comparison of various approaches to cooperative control. Ideally, metrics would be available that provide quantitative evaluations of cooperative robot teams based upon high-level design goals, such as fault tolerance, adaptivity, and so forth. In current research, however, metrics are limited to application-dependent measures. This paper summarizes the metrics that have been used in eight implementations of the ALLIANCE architecture in multi-robot teams. We explore the implications of the chosen metrics and offer suggestions for developing less application-dependent metrics in the future.\",\n \"Title: The SDR Experience: Experiments with a Large-Scale Heterogeneous Mobile Robot Team\\nYear: 2004\\n\\nAbstract: This paper reports on experiments conducted as part of the DARPA SDR (Software for Distributed Robotics) program. The core challenge for this program is to develop a system capable of carrying out 'locate-and-protect' missions: the system must be able to deploy a large number of robots into an unexplored building, map the building interior, locate a valued object, detect and track intruders, and transmit all of the above information to a remote observer/operator. To satisfy these requirements, we have developed a large heterogeneous robot team consisting of approximately 80 robots. This paper sketches the key technical elements of this system, and presents selected results from externally supervised experiments conducted in a 600 m2 indoor environment.\",\n \"Title: Planning mobile sensor net deployment for navigationally-challenged sensor nodes\\nYear: 2004\\n\\nAbstract: This wok describes novel algorithms for planning the deployment of a large number of navigationally-challenged mobile sensor nodes in known indoor environments. Due to cost and power constraints, our mobile sensor nodes have the ability to move and communicate, but they cannot detect or avoid obstacles or localize to the environment. Additionally, they have only minimal capabilities for detecting other robot team members, through the use of a crude camera. Our deployment process, therefore, uses an assistive navigation technique that enables a more capable leader robot, equipped with a laser rangefinder and a camera, to guide several mobile sensor nodes to their deployment positions. To ensure the successful deployment of the mobile sensor nodes, we have developed an autonomous planning process that plans the positions of the sensor nodes based upon a number of constraints, including maintaining line of sight maximizing visibility coverage, avoiding placement in doorways, minimizing obstruction of corridors, and so forth. Additionally, because of the navigational constraints of simple robots following a leader to these deployment positions, our algorithm also derives two leader waypoints for each sensor position, which on strain the motion of the leader path to the deployment position. These leader\",\n \"Title: Toward the Automated Synthesis of Cooperative Mobile Robot Teams\\nYear: 1998\\n\\nAbstract: A current limitation in the real-world use of cooperating mobile robots is the difficulty in determining the proper team composition for a given robotic application. Present technology restricts the design and implementation of cooperative robot teams to the expertise of a robotics researcher, who has to develop robot teams on an application-specific basis. The objective of our research is to reduce the complexity of cooperative robotic systems through the development of a methodology that enables the automated synthesis of cooperative robot teams. We propose an approach to this problem that uses a combination of the theories of sensori-computational systems and information invariants, building on the earlier work of Donald, Rus, et al. We describe the notion of defining equivalence classes that serve as fundamental building blocks of more complex cooperative mobile robot behaviors. We postulate a methodology for framing mission requirements in terms of the goals and constraints of the problem, incorporating issues such as multi-robot interference, communication, control strategy, robot complexity, and so forth, into the mechanism. Our initial work restricts the robot application and design space to three multi-robot application domains we have previously studied and implemented: keeping formation, \\\"mock\\\" hazardous waste cleanup, and cooperative observation. This paper presents the foundational ideas upon which our approach to cooperative team design is based.\",\n \"Title: Indoor Target Intercept Using An Acoustic Sensor Network And Dual Wavefront Path Planning\\nYear: 2003\\n\\nAbstract: This paper presents an approach that enables a mobile \\\"Interceptor\\\" robot to intercept targets in an indoor environment using information from a distributed acoustic sensor network. The approach assurnes the indoor environment has been previously mapped and that the sensor nodes know their position in the map. The targets are localized in the sensor network based upon local maxima of the acoustic volume. The current target localization information is reported to an Interceptor robot, which utilizes a dual wavefront path planner to move from its current location to a location that is within viisibility range of a target. Results of the complete implementation of this approach using 70 sensor net robots in the Player/Stage multi-robot simulator are reported, as well as implementation results to date on a team of physical robots. To our knowledge, this is the first implementation of a multi-robot system that combines the use of an acoustic sensor net for target detection with an Interceptor robot that can efficiently reach the moving position of the detected target in indoor environments.\",\n \"Title: Nearest neighbor imputation using spatial-temporal correlations in wireless sensor networks.\\nYear: 2014\\n\\nAbstract: Missing data is common in Wireless Sensor Networks (WSNs), especially with multi-hop communications. There are many reasons for this phenomenon, such as unstable wireless communications, synchronization issues, and unreliable sensors. Unfortunately, missing data creates a number of problems for WSNs. First, since most sensor nodes in the network are battery-powered, it is too expensive to have the nodes re-transmit missing data across the network. Data re-transmission may also cause time delays when detecting abnormal changes in an environment. Furthermore, localized reasoning techniques on sensor nodes (such as machine learning algorithms to classify states of the environment) are generally not robust enough to handle missing data. Since sensor data collected by a WSN is generally correlated in time and space, we illustrate how replacing missing sensor values with spatially and temporally correlated sensor values can significantly improve the network’s performance. However, our studies show that it is important to determine which nodes are spatially and temporally correlated with each other. Simple techniques based on Euclidean distance are not sufficient for complex environmental deployments. Thus, we have developed a novel Nearest Neighbor (NN) imputation method that estimates missing data in WSNs by learning spatial and temporal correlations between sensor nodes. To improve the search time, we utilize a kd-tree data structure, which is a non-parametric, data-driven binary search tree. Instead of using traditional mean and variance of each dimension for kd-tree construction, and Euclidean distance for kd-tree search, we use weighted variances and weighted Euclidean distances based on measured percentages of missing data. We have evaluated this approach through experiments on sensor data from a volcano dataset collected by a network of Crossbow motes, as well as experiments using sensor data from a highway traffic monitoring application. Our experimental results show that our proposed K-NN imputation method has a competitive accuracy with state-of-the-art Expectation–Maximization (EM) techniques, while using much simpler computational techniques, thus making it suitable for use in resource-constrained WSNs.\",\n \"Title: L-ALLIANCE: Task-Oriented Multi-Robot Learning in Behaviour-Based Systems\\nYear: 1996\\n\\nAbstract: A large application domain for multi-robot teams involves task-oriented missions, in which potentially heterogeneous robots must solve several distinct tasks. Previous research addressing this problem in multi-robot systems has largely focused on issues of efficiency, while ignoring the real-world situated robot needs of fault tolerance and adaptivity. This paper addresses this problem by developing an architecture called L-ALLIANCE that incorporates task-oriented action selection mechanisms into a behavior-based system, thus increasing the efficiency of robot team performance while maintaining the desirable characteristics of fault tolerance and adaptivity. We present our investigations of several competing control strategies and derive an approach that works well in a wide variety of multi-robot task-oriented mission scenarios. We provide a formal model of this technique to illustrate how it can be incorporated into any behavior-based system.\",\n \"Title: Calibrating building energy models using supercomputer trained machine learning agents\\nYear: 2014\\n\\nAbstract: Building energy modeling BEM is an approach to model the energy usage in buildings for design and retrofit purposes. EnergyPlus is the flagship Department of Energy software that performs BEM for different types of buildings. The input to EnergyPlus can often extend in the order of a few thousand parameters that have to be calibrated manually by an expert for realistic energy modeling. This makes it challenging and expensive thereby making BEM unfeasible for smaller projects. In this paper, we describe the 'Autotune' research that employs machine learning algorithms to generate agents for the different kinds of standard reference buildings in the US building stock. The parametric space and the variety of building locations and types make this a challenging computational problem necessitating the use of supercomputers. Millions of EnergyPlus simulations are run on supercomputers that are subsequently used to train machine learning algorithms to generate agents. These agents, once created, can then run in a fraction of the time thereby allowing cost-effective calibration of building models. Published 2014. This article is a US Government work and is in the public domain in the USA.\",\n \"Title: Fuzzy segmentation and recognition of continuous human activities\\nYear: 2014\\n\\nAbstract: Most previous research has focused on classifying single human activities contained in segmented videos. However, in real-world scenarios, human activities are inherently continuous and gradual transitions always exist between temporally adjacent activities. In this paper, we propose a Fuzzy Segmentation and Recognition (FuzzySR) algorithm to explicitly model this gradual transition. Our goal is to simultaneously segment a given video into events and recognize the activity contained in each event. Specifically, our algorithm uniformly partitions the video into a sequence of non-overlapping blocks, each of which lasts a short period of time. Then, a multi-variable time series is creatively formed through concatenating the block-level human activity summaries that are computed using topic models over each block's local spatio-temporal features. By representing an event as a fuzzy set that has fuzzy boundaries to model gradual transitions, our algorithm is able to segment the video into a sequence of fuzzy events. By incorporating all block summaries contained in an event, the proposed algorithm determines the most appropriate activity category for each event. We evaluate our algorithm's performance using two real-world benchmark datasets that are widely used in the machine vision community. We also demonstrate our algorithm's effectiveness in important robotics applications, such as intelligent service robotics. For all used datasets, our algorithm achieves promising continuous human activity segmentation and recognition results.\",\n \"Title: Coalition coordination for tightly coupled multirobot tasks with sensor constraints\\nYear: 2014\\n\\nAbstract: Although many approaches have been developed to form robot coalitions that can achieve a multirobot task, no general methods exist to execute these coalitions, especially when the coordination among the robots is tightly coupled. In this paper, we propose a coordination mechanism as the first step to address coalition execution; it provides a flexible method to reason about synergies with overlapping coalitions (thus enabling multi-tasking robots in multi-robot tasks), which not only improves efficiency, but also reduces resource requirements in task execution. This means that our approach enables tasks that cannot be easily handled before, especially when critical resources are rare but commonly required. Our approach is based on the concept of sensor constraint, which is introduced by the tight coupling (e.g., information sharing) between the robots. We show that our algorithm is sound and complete in finding a coordination solution given a few assumptions, and discuss a distributed implementation. Simulation results are provided to demonstrate the capabilities of this new approach.\",\n \"Title: Simplex-Based 3D Spatio-temporal Feature Description for Action Recognition\\nYear: 2014\\n\\nAbstract: We present a novel feature description algorithm to describe 3D local spatio-temporal features for human action recognition. Our descriptor avoids the singularity and limited discrimination power issues of traditional 3D descriptors by quantizing and describing visual features in the simplex topological vector space. Specifically, given a feature's support region containing a set of 3D visual cues, we decompose the cues' orientation into three angles, transform the decomposed angles into the simplex space, and describe them in such a space. Then, quadrant decomposition is performed to improve discrimination, and a final feature vector is composed from the resulting histograms. We develop intuitive visualization tools for analyzing feature characteristics in the simplex topological vector space. Experimental results demonstrate that our novel simplex-based orientation decomposition (SOD) descriptor substantially outperforms traditional 3D descriptors for the KTH, UCF Sport, and Hollywood-2 benchmark action datasets. In addition, the results show that our SOD descriptor is a superior individual descriptor for action recognition.\",\n \"Title: A distributed and optimal motion planning approach for multiple mobile robots\\nYear: 2002\\n\\nAbstract: We propose a distributed and optimal motion planning algorithm for multiple robots. The computationally expensive problem is decomposed into two modules: path planning and velocity planning. The D* search method is applied in both modules, based on either geometric formulation or schedule formulation. Optimization is achieved at the individual robot level by defining cost functions, and also at the team level by a global measurement function reflecting performance indices of interest as a team. Contrary to our knowledge of previous results on multi-robot motion planning that either obtain optimal solutions through centralized and exhaustive computing, or achieve distributed implementations without considering any optimization issues, our approach combines these two features and explicitly optimizes performance functions through a distributed implementation. It is also one of the few that is capable of handling outdoor rough terrain environments and real time replanning. Simulations are shown on a Mars-like rough terrain using a 3D vehicle planner and control simulator. The algorithm was also implemented and successfully run on a group of Nomad 200 indoor robots\",\n \"Title: Cooperative leader following in a distributed multi-robot system\\nYear: 2002\\n\\nAbstract: The cooperative leader following task for multi-robot teams is introduced and discussed. We describe the design and implementation of a distributed technique to coordinate team level and robot level behaviors for this task, as well as a multi-threaded framework for the implementation of a multi-robot system with heterogeneous sensing capabilities. This approach enables robots to remain in formation as they deal with other obstacles that may appear within the formation. We describe how single robot behaviors are realized and scheduled. We show some of the results of the team implementations. The proposed approach has been run and validated on a team of robots performing both in indoor and outdoor environments\",\n \"Title: Distributed heterogeneous outdoor multi-robot localization\\nYear: 2002\\n\\nAbstract: An Extended Kalman Filter-based algorithm for the localization of a team of robots is described in this paper. The distributed EKF localization scheme is straightforward in that the individual robots maintain a pose estimate using EKFs that are local to every robot. We then show how these results can be extended to perform heterogeneous cooperative localization in the absence or degradation of absolute sensors aboard the team members. The proposed algorithms are implemented using field data obtained from a team of ATRV-Mini robots traversing on have a fully centralized scheme for the control of mul- tiple robots as the increase in computational overhead is proportional to the number of robots in the team. When there is no central processing facility and all the decisional issues for a team member are tackled within the robot itself, the disadvantages associated with the centralized architectures can be overcome. This moti- vation has manifest itself into decentralized (and dis- tributed) architectures that render robust and modular capabilities (3). Localization, the process of determining the position and orientation (pose) of a robot within the operating environment, is critical for subsequent high level nav- igation tasks. Each member of the robot team con- sidered in this paper possesses absolute positioning ca- pability by means of differential GPS (DGPS). Multi- pathing 1 errors make it extremely difficult to localize based on DGPS alone. Thus it becomes necessary to develop a framework within which observations from dead-reckoning and absolute sensors can be fused to continually deliver reliable and consistent pose esti- mates. Additionally, in order to minimize the com- putational bottlenecks associated with centralized ar- chitectures for multi-robot localization, we seek to de- centralize the estimation process across the members of the group. To achieve the above requirements, a distributed Extended Kalman Filter-based algorithm for the localization of a team of robots operating on outdoor terrain is developed in this paper. In the first part of the paper, we show that distributed localization of robot team members can be realized in a straight- forward manner by enabling each robot to maintain its pose using an EKF that is local to that particular robot. The resulting pose estimates are intended to aid the construction of an elevation map (described in a companion paper (4)). We also consider the case when\",\n \"Title: Guest editorial advances in multirobot systems\\nYear: 2002\\n\\nAbstract: As research progresses in distributed robotic systems, more and more aspects of multirobot systems are being explored. This Special Issue on Advances in Multirobot Systems provides a broad sampling of the research that is currently ongoing in the field of distributed mobile robot systems. To help categorize this research, we have identified seven primary research topics within multirobot systems: biological inspirations, communication, architectures, localization/mapping/exploration, object transport and manipulation, motion coordination, and reconfigurable robots. This editorial examines these research areas and discusses the Special Issue papers in this context. We conclude by identifying several additional open research issues in distributed mobile robotic systems.\",\n \"Title: Task-oriented multi-robot learning in behavior-based systems\\nYear: 1996\\n\\nAbstract: A large application domain for multi-robot teams involves task-oriented missions, in which potentially heterogeneous robots must solve several distinct tasks. Previous research addressing this problem in multi-robot systems has largely focused on issues of efficiency, while ignoring the real-world situated robot needs of fault tolerance and adaptivity. This paper addresses this problem by developing an architecture called L-ALLIANCE that incorporates task-oriented action selection mechanisms into a behavior-based system, thus increasing the efficiency of robot team performance while maintaining the desirable characteristics of fault tolerance and adaptivity. We present our investigations of several competing control strategies and derive an approach that works well in a wide variety of multi-robot task-oriented mission scenarios. We provide a formal model of this technique to illustrate how it can be incorporated into any behavior-based system\",\n \"Title: Building Multirobot Coalitions Through Automated Task Solution Synthesis\\nYear: 2006\\n\\nAbstract: ABSTRACT | This paper,presents,a reasoning,system,that enables,a group,of heterogeneous,robots,to form,coalitions to accomplish,a multirobot task using tightly coupled,sensor sharing. Our approach, which we call ASyMTRe, maps environmental,sensors,and perceptual and motor control schemas,to the required,flow of information,through,the multirobot,system, automatically reconfiguring the connections of schemas within and across robots to synthesize,valid and,efficient multirobot,behaviors,for accomplishing,a multirobot,task. We present,the centralized,anytime,ASyMTRe configuration,algorithm, proving that the algorithm is correct, and formally addressing,issues,of completeness,and,optimality.,We then present a distributed version of ASyMTRe, called ASyMTRe-D, which,uses communication,to enable,distributed,coalition formation. We validate the centralized,approach,by applying,the ASyMTRe methodology,to two,application,scenarios: multirobot transportation and multirobot box pushing.,We then validate,the,ASyMTRe-D implementation,in the multirobot transportation task, illustrating its fault-tolerance capabilities. The advantages,of this new,approach,are that it: 1) enables robots,to synthesize,new,task solutions,using,fundamentally different combinations,of sensors and effectors for different coalition compositions,and,2) provides,a general,mechanism for sharing sensory information across networked,robots. , formation;,information,invariants;\",\n \"Title: Metrics for quantifying system performance in intelligent, fault-tolerant multi-robot teams\\nYear: 2007\\n\\nAbstract: Any system that has the capability to diagnose and recover from faults is considered to be a fault-tolerant system. Additionally, the quality of the incorporated fault-tolerance has a direct impact on the overall performance of the system. Hence, being able to measure the extent and usefulness of fault- tolerance exhibited by the system would provide the designer with a useful analysis tool for better understanding the system as a whole. Unfortunately, it is difficult to quantify system fault-tolerance on its own for intelligent systems. A more useful metric for evaluation is the \\\"effectiveness\\\" measure of fault- tolerance. The influence of fault-tolerance towards improving overall performance determines the overall effectiveness or quality of the system. In this paper, we outline application- independent metrics to measure fault-tolerance within the context of system performance. In addition, we also outline potential methods to better interpret the obtained measures towards understanding the capabilities of the implemented system. Furthermore, a main focus of our approach is to capture the effect of intelligence, reasoning, or learning on the effective fault-tolerance of the system, rather than relying purely on traditional redundancy based measures. We show the utility of the designed metrics by applying them to different fault-tolerance architectures implemented for multiple complex heterogeneous multi-robot team applications and comparing system performance. Finally, we contrast the developed metrics with the only other existing method (HWB method) for evaluating (that we are aware of) effective fault-tolerance for multi-robot teams and rate them in terms of their capability to best interpret the workings of the implemented systems. To the best of our knowledge, this is the first metric that attempts to evaluate the quality of learning towards understanding system level fault-tolerance.\",\n \"Title: Using critical junctures and environmentally-dependent information for management of tightly-coupled cooperation in heterogeneous robot teams\\nYear: 2009\\n\\nAbstract: This paper addresses the challenge of forming appropriate heterogeneous robot teams to solve tightly-coupled, potentially multi-robot tasks, in which the robot capabilities may vary over the environment in which the task is being performed. Rather than making use of a permanent tightly-coupled robot team for performing the task, our approach aims to recognize when tight coupling is needed, and then only form tight cooperative teams at those times. This results in important cost savings, since coordination is only used when the independent operation of the team members would put mission success at risk. Our approach is to define a new semantic information type, called environmentally dependent information, which allows us to capture certain environmentally-dependent perceptual constraints on vehicle capabilities. We define locations at which the robot team must transition between tight and weak cooperation as critical junctures. Note that these critical juncture points are a function of the robot team capabilities and the environmental characteristics, and are not due to a change in the task itself. We calculate critical juncture points by making use of our prior ASyMTRe approach, which can automatically configure heterogeneous robot team solutions to enable sharing of sensory capabilities across robots. We demonstrate these concepts in experiments involving a human-controlled blimp and an autonomous ground robot in a target localization task.\",\n \"Title: Fuzzy Temporal Segmentation and Probabilistic Recognition of Continuous Human Daily Activities\\nYear: 2015\\n\\nAbstract: Understanding human activities is an essential capability for intelligent robots to help people in a variety of applications. Humans perform activities in a continuous fashion, and transitions between temporally adjacent activities are gradual. Our Fuzzy Segmentation and Recognition (FuzzySR) algorithm explicitly reasons about gradual transitions between continuous human activities. Our objective is to simultaneously segment a given video into a sequence of events and recognize the activity contained in each event. The algorithm uniformly segments the video into a sequence of nonoverlapping blocks, each lasting a short period of time. Then, a multivariable time series is formed by concatenating block-level human activity summaries that are computed using topic models over local spatiotemporal features extracted from each block. Through encoding an event as a fuzzy set with fuzzy boundaries to represent gradual transitions, our approach is capable of segmenting the continuous visual data into a sequence of fuzzy events. By incorporating all block summaries contained in an event, our algorithm determines the activity label for each event. To evaluate performance, we conduct experiments using six datasets. Our algorithm shows promising continuous activity segmentation results on these datasets and obtains the event-level activity recognition precision of 42.6%, 60.4%, 65.2%, and 78.9% on the Hollywood-2, CAD-60, ACT , and UTK-CAP datasets, respectively.\",\n \"Title: Cooperative Robotics For Multi-Target Observation\\nYear: 1999\\n\\nAbstract: An important issue that arises in the automation of many security, surveillance and reconnaissance tasks is that of observing (or monitoring) the movements of targets navigating in a bounded area of interest. A key research issue in these problems is that of sensor placement-determining where sensors should be located to maintain the targets in view. In complex applications involving limited-range sensors, the use of multiple sensors dynamically moving over time is required. In this article, we investigate the use of a cooperative team of autonomous sensor-based robots for the observation of multiple moving targets (a problem that we term CMOMMT). We focus primarily on developing the distributed control strategies that allow the robot team to attempt to maximize the collective time during which each target is being observed by at least one robot team member in the area of interest. Our initial efforts on this problem address the aspects of distributed control in robot teams with equivalent movement capabilities working in an uncluttered, bounded area This article first formalizes the problem and discusses related work. We then present a distributed approximate approach to solving this problem (called A-CMOMMT) that combines low-level multi-robot control with higher-level control. The low-level control is described in terms of force fields emanating from the targets and the robots. The higher level control is presented in our ALLANCE formalism[16,17], which provides mechanisms for fault tolerant cooperative control, and allows robot ream members to adjust their low-level actions based upon the actions of their teammates. We then present the results of the ongoing implementation of our approach, both in simulation and on physical robots. To our knowledge, this is the first article addressing this research problem that has been implemented on physical robot teams.\",\n \"Title: CoDe4D: Color-Depth Local Spatio-Temporal Features for Human Activity Recognition From RGB-D Videos.\\nYear: 2016\\n\\nAbstract: Human activity recognition has a variety of important real-world applications, such as video analysis, surveillance, and human-robot interaction. As a promising video representation method, local spatio-temporal (LST) features have received increasing attention from computer vision, machine learning, and robotics communities. However, approaches based on traditional LST features only use color inf...\",\n \"Title: Self-Reflective Risk-Aware Artificial Cognitive Modeling for Robot Response to Human Behaviors.\\nYear: 2016\\n\\nAbstract: In order for cooperative robots (\\\"co-robots\\\") to respond to human behaviors accurately and efficiently in human-robot collaboration, interpretation of human actions, awareness of new situations, and appropriate decision making are all crucial abilities for co-robots. For this purpose, the human behaviors should be interpreted by co-robots in the same manner as human peers. To address this issue, a novel interpretability indicator is introduced so that robot actions are appropriate to the current human behaviors. In addition, the complete consideration of all potential situations of a robot's environment is nearly impossible in real-world applications, making it difficult for the co-robot to act appropriately and safely in new scenarios. This is true even when the pretrained model is highly accurate in a known situation. For effective and safe teaming with humans, we introduce a new generalizability indicator that allows a co-robot to self-reflect and reason about when an observation falls outside the co-robot's learned model. Based on topic modeling and two novel indicators, we propose a new Self-reflective Risk-aware Artificial Cognitive (SRAC) model. The co-robots are able to consider action risks and identify new situations so that better decisions can be made. Experiments both using real-world datasets and on physical robots suggest that our SRAC model significantly outperforms the traditional methodology and enables better decision making in response to human activities.\",\n \"Title: Unified robot learning of action labels and motion trajectories from 3D human skeletal data\\nYear: 2016\\n\\nAbstract: Currently, robot learning of human activities is mainly studied in two largely disconnected domains: high level semantics understanding in human activity recognition, and low level motion trajectory reproduction in robot imitation learning. The critical problem of human activity unified learning (HAUL) was not well studied in previous work. One important challenge is the lack of a representation that can be learned from both levels. We introduce a novel approach to address this HAUL problem at the representation level, by simultaneously learning action labels and motion trajectories from publicly available 3D human skeletal datasets, thus avoiding additional human labor for data collection. Our approach builds a subject and body position independent shared skeleton, and extracts features of skeletal activities based on this model. Then the extracted features are encoded by the parameter set of Gaussian Mixture Models to construct the unified representations. The proposed compact representation can be directly applied to identify activity labels when combined with Support Vector Machines, and can be also employed to generate trajectories of the learned activities when combined with Gaussian Mixture Regression on a robot. Finally, an inverse kinematic mapping is developed to transfer human skeletal trajectories to joint angle sequences in the robot's embodiment. Empirical studies using simulation and real humanoid robots demonstrate that our approach achieves promising performance on robot unified learning of human action labels and motion trajectories, effectively addressing the HAUL problem.\",\n \"Title: Minimum uncertainty latent variable models for robot recognition of sequential human activities.\\nYear: 2017\\n\\nAbstract: Recognition of sequential human activities, such as “sitting down” and “standing up”, is a common but challenging problem in human-robot interaction, which requires modeling their underlying temporal patterns. Although previous sequence modeling methods, such as Hidden Conditional Random Fields (HCRFs), demonstrated satisfactory recognition accuracy, they do not explicitly model the uncertainty in underlying temporal patterns, which can provide valuable information to characterize sequential activities. To address this problem, we introduce a novel Minimum Uncertainty HCRF (MU, or μHCRF). Different from traditional HCRF-based techniques that only utilize the negative log-likelihood of the categoriesu0027 conditional probability as the loss function, the proposed μ-HCRF also introduces a regularization term to model the underlying temporal pattern of the latent variables. As another theoretical contribution, we provide a derivation to show that the formulated problem has a closed-form solution, and prove that inference of the proposed μHCRF is tractable. Extensive empirical study is performed to evaluate our approach, using four public benchmark datasets. Experimental results have shown that our μHCRFs outperform previous techniques and achieve state-of-the-art performance on human activity recognition, especially on sequential activities.\",\n \"Title: Skeleton-based bio-inspired human activity prediction for real-time human–robot interaction\\nYear: 2018\\n\\nAbstract: Activity prediction is an essential task in practical human-centered robotics applications, such as security, assisted living, etc., which is targeted at inferring ongoing human activities based on incomplete observations. To address this challenging problem, we introduce a novel bio-inspired predictive orientation decomposition (BIPOD) approach to construct representations of people from 3D skeleton trajectories. BIPOD is invariant to scales and viewpoints, runs in real-time on basic computer systems, and is able to recognize and predict activities in an online fashion. Our approach is inspired by biological research in human anatomy. To capture spatio-temporal information of human motions, we spatially decompose 3D human skeleton trajectories and project them onto three anatomical planes (i.e., coronal, transverse and sagittal planes); then, we describe short-term time information of joint motions and encode high-order temporal dependencies. By using Extended Kalman Filters to estimate future skeleton trajectories, we endow our BIPOD representation with the critical capabilities to reduce noisy skeleton observation data and predict the ongoing activities. Experiments on benchmark datasets have shown that our BIPOD representation significantly outperforms previous methods for real-time human activity classification and prediction from 3D skeleton trajectories. Empirical studies using TurtleBot2 and Baxter humanoid robots have also validated that our BIPOD method obtains promising performance, in terms of both accuracy and efficiency, making BIPOD a fast, simple, yet powerful representation for low-latency online activity prediction in human–robot interaction applications.\",\n \"Title: Creation of the National Artificial Intelligence Research and Development Strategic Plan.\\nYear: 2018\\n\\nAbstract: In October 2016, the United States government published the National Artificial Intelligence Research and Development Strategic Plan, which lays out a strategic plan for federally funded research and development in AI. As a coleader of the task force that developed this plan, I was asked to discuss its creation in an invited presentation at AAAI 2017. This article is based on that presentation, which outlines not only the plan itself, but also provides insight into its goads and objectives, and background into how it was created.\",\n \"Title: Human Spatio-Temporal Attention Modeling Using Head Pose Tracking for Implicit Object of Interest Discrimination in Robot Agents\\nYear: 2018\\n\\nAbstract: Hazardous search missions are an excellent application domain for human-robot teams because cost-effective robot systems could be leveraged to reduce total mission duration time, improve search space thoroughness, and reduce human exposure to danger. Efficiently pairing robotic agents with human workers requires leveraging implicit communication when explicit techniques are either unavailable, socially unnatural, or impractical, such as is often the case with challenging search and rescue missions. Although successful implicit communication methods for robotics systems exist, (e.g., gestural recognition, activity recognition, and gaze management), a full suite of effective natural communication skills remains an open problem in robotics, thus preventing human-robot team solutions from being more commonplace. To help address this capability gap, we introduce a technique to implicitly model human spatio-temporal attention with a 3D heat map based on head pose trajectory tracking. We then show that this version of attention modeling can be applied by a robot agent to reliably extract Object of Interest (OOI) information for use in improving implicit communication in human-robot teams. This technique is evaluated in an OOI search task and a shared workspace clustered OOI discrimination task.\",\n \"Title: Robots Can Teach Students With Intellectual Disabilities: Educational Benefits of Using Robotic and Augmented Reality Applications\\nYear: 2019\\n\\nAbstract: In the face of a worldwide teacher shortage and, in the United States, a critical shortage of special education teachers, there is an urgent demand for appropriate educational resources. For people with intellectual and developmental disabilities (I/DDs), in particular, there is a compelling need to develop educational tools and strategies to facilitate independence and self-sufficiency and address poor employment outcomes in adulthood.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":66,"string":"66"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":58,"string":"58"}}},{"rowIdx":59,"cells":{"question_id":{"kind":"string","value":"Jeffrey A Fessler"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Recursive Algorithm For Computing Cramer-Rao-Type Bounds On Estimator Covariance\" using the following items: recursive algorithm, Cramer-Rao matrix bound, exponential convergence, splitting matrix, image reconstruction."},"answer":{"kind":"string","value":"We give a recursive algorithm to calculate submatrices of the Cramer-Rao (CR) matrix bound on the covariance of any unbiased estimator of a vector parameter theta. Our algorithm computes a sequence of lower bounds that converges monotonically to the CR bound with exponential speed of convergence. The recursive algorithm uses an invertible ''splitting matrix'' to successively approximate the inverse Fisher information matrix. We present a statistical approach to selecting the splitting matrix based on a ''complete-data-incomplete-data'' formulation similar to that of the well-known EM parameter estimation algorithm. As a concrete illustration we consider image reconstruction from projections for emission computed tomography."},"correct_answer":{"kind":"string","value":"We give a recursive algorithm to calculate submatrices of the Cramer-Rao (CR) matrix bound on the covariance of any unbiased estimator of a vector parameter theta. Our algorithm computes a sequence of lower bounds that converges monotonically to the CR bound with exponential speed of convergence. The recursive algorithm uses an invertible ''splitting matrix'' to successively approximate the inverse Fisher information matrix. We present a statistical approach to selecting the splitting matrix based on a ''complete-data-incomplete-data'' formulation similar to that of the well-known EM parameter estimation algorithm. As a concrete illustration we consider image reconstruction from projections for emission computed tomography."},"documents":{"kind":"list like","value":["Title: Cross-validation and predicted risk estimation for nonlinear iterative reweighted least-squares MRI reconstruction.\nYear: 2012\n\nAbstract: Regularization is an effective means of reducing noise and artifacts in MR image reconstruction from undersampled k-space data. Proper application of regularization demands appropriate selection of the associated regularization parameter. Generalized cross-validation (GCV) is a popular parameter tuning technique especially for linear reconstruction methods, but its application to nonlinear iterative MRI reconstruction is more involved as it demands the evaluation of the Jacobian matrix of the reconstruction algorithm with respect to complex-valued data. We derive analytical expressions for recursively updating this Jacobian matrix for an iterative reweighted least-squares reconstruction algorithm. Our method can also be used to calculate a predicted risk estimate (PSURE) for MRI based on Stein's principle. We demonstrate with simulations and experiments with real data that regularization parameter selection based on GCV and PSURE provides near-MSE-optimal results for nonlinear MRI reconstruction from undersampled k-space data using l(1)-regularization.","Title: Asymptotic Source Detection Performance of Gamma-Ray Imaging Systems Under Model Mismatch\nYear: 2011\n\nAbstract: Likelihood-based test statistics for the task of detecting a radioactive source in background using a gamma-ray imaging system often have intractable distributions. This complicates the tasks of predicting detection performance and setting thresholds that ensure desired false-alarm rates. Asymptotic distributions of test statistics can aid in predicting performance and in setting detection thresholds. However, in applications with complex sensors, like gamma-ray imaging, often only approximate statistical models for the measurements are available. Standard asymptotic approximations can yield inaccurate performance predictions when based on misspecified models. This paper considers asymptotic properties of detection tests based on maximum likelihood (ML) estimates under model mismatch, i.e., when the statistical model used for detection differs from the true distribution. We provide general expressions for the asymptotic distribution of likelihood-based test statistics when the number of measurements is Poisson, and expressions specific to gamma-ray source detection that one can evaluate using a modest amount of data from a real system or Monte Carlo simulation. Considering a simulated Compton imaging system, we show that the proposed expressions yield more accurate detection performance predictions than previous expressions that ignore model mismatch. These expressions require less data and computation than conventional empirical methods.","Title: Respiratory Motion Estimation From Slowly Rotating X-Ray Projections\nYear: 2004\n\nAbstract: As radiotherapy has become increasingly conformal, geometric uncertainties caused by breathing and organ motion have become an important issue. Accurate motion estimates may lead to improved treatment planning and dose calculation in radiation therapy. However, respiratory motion is difficult to study by conventional X-ray CT imaging since object motion causes inconsistent projection views leading to artifacts in reconstructed images.We propose to estimate the parameters of a nonrigid motion model from a set of projection views of the thorax that are acquired using a slowly rotating cone-beam CT scanner, such as a radiotherapy simulator. We use a conventionally reconstructed 3D thorax image, acquired by breath-hold CT, as a reference volume. We represent respiratory motion using a flexible parametric nonrigid motion model based on B-splines. The motion parameters are estimated by optimizing a regularized cost function that includes the squared error between the measured projection views and the reprojections of the deformed reference image. Preliminary 2D simulation results show that there is good agreement between the estimated motion and the true motion.","Title: New Statistical Models for Randoms-Precorrected PET Scans\nYear: 1997\n\nAbstract: PET measurements are usually precorrected for accidental coincidence events by real-time subtraction of the delayed window coincidences. Randoms subtraction compensates in mean for accidental coincidences but destroys the Poisson statistics. We propose and analyze two new approximations to the exact log-likelihood of the precorrected measurements, one based on a \"shifted Poisson\" model, the other based on saddle-point approximations to the measurement probability mass function (pmf). The methods apply to both emission and transmission tomography; however in this paper we focus on transmission tomography. We compare the new models to conventional data-weighted least squares (WLS) and conventional maximum likelihood (based on the ordinary Poisson (OP) model) using simulations and analytic approximations. The results demonstrate that the proposed methods avoid the systematic bias of the WLS method, and lead to significantly lower variance than the conventional OP method. The saddle-point method provides a more accurate approximation to the exact log-likelihood than the WLS, OP and shifted Poisson alternatives. However, the simpler shifted Poisson method yielded comparable bias-variance performance in the simulations. The new methods offer improved image reconstruction in PET through more realistic statistical modeling, yet with negligible increase in computation over the conventional OP method.","Title: Analytical Approach to Channelized Hotelling Observer Performance For Regularized Tomographic Image Reconstruction\nYear: 2004\n\nAbstract: Our goal is to analyze regularized image reconstruction meth- ods such as penalized likelihood with respect to the perfor- mance of the Channelized Hotelling Observer (CHO) in the task of detecting a small target signal in the reconstructed images, in the presence of a correlated random background. We derive here an approximation to the performance of the CHO by working entirely with continuous-space formula- tions and then discretizing the nal result. This approach leads to an extension and a renement of approximations that we previously derived in the discrete space.","Title: Accelerated Regularized Estimation of MR Coil Sensitivities Using Augmented Lagrangian Methods.\nYear: 2013\n\nAbstract: Several magnetic resonance parallel imaging techniques require explicit estimates of the receive coil sensitivity profiles. These estimates must be accurate over both the object and its surrounding regions to avoid generating artifacts in the reconstructed images. Regularized estimation methods that involve minimizing a cost function containing both a data-fit term and a regularization term provide robust sensitivity estimates. However, these methods can be computationally expensive when dealing with large problems. In this paper, we propose an iterative algorithm based on variable splitting and the augmented Lagrangian method that estimates the coil sensitivity profile by minimizing a quadratic cost function. Our method, ADMM-Circ, reformulates the finite differencing matrix in the regularization term to enable exact alternating minimization steps. We also present a faster variant of this algorithm using intermediate updating of the associated Lagrange multipliers. Numerical experiments with simulated and real data sets indicate that our proposed method converges approximately twice as fast as the preconditioned conjugate gradient method over the entire field-of-view. These concepts may accelerate other quadratic optimization problems.","Title: Accelerated Edge-Preserving Image Restoration Without Boundary Artifacts\nYear: 2013\n\nAbstract: To reduce blur in noisy images, regularized image restoration methods have been proposed that use nonquadratic regularizers (like $l_{1}$ regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a noncirculant model could prevent these artifacts at the cost of increased computational complexity. In this paper, we propose to use a circulant blur model combined with a masking operator that prevents wraparound artifacts. The resulting model is noncirculant, so we propose an efficient algorithm using variable splitting and augmented Lagrangian (AL) strategies. Our variable splitting scheme, when combined with the AL framework and alternating minimization, leads to simple linear systems that can be solved noniteratively using fast Fourier transforms (FFTs), eliminating the need for more expensive conjugate gradient-type solvers. The proposed method can also efficiently tackle a variety of convex regularizers, including edge-preserving (e.g., total-variation) and sparsity promoting (e.g., $l_{1}$-norm) regularizers. Simulation results show fast convergence of the proposed method, along with improved image quality at the boundaries where the circulant model is inaccurate.","Title: Iterative tomographic image reconstruction using Fourier-based forward and back-projectors.\nYear: 2004\n\nAbstract: Iterative image reconstruction algorithms play an increasingly important role in modern tomographic systems, especially in emission tomography. With the fast increase of the sizes of the tomographic data, reduction of the computation demands of the reconstruction algorithms is of great importance. Fourier-based forward and back-projection methods have the potential to considerably reduce the computation time in iterative reconstruction. Additional substantial speed-up of those approaches can be obtained utilizing powerful and cheap off-the-shelf fast Fourier transform (FFT) processing hardware. The Fourier reconstruction approaches are based on the relationship between the Fourier transform of the image and Fourier transformation of the parallel-ray projections. The critical two steps are the estimations of the samples of the projection transform, on the central section through the origin of Fourier space, from the samples of the transform of the image, and vice versa for back-projection. Interpolation errors are a limitation of Fourier-based reconstruction methods. We have applied min-max optimized Kaiser-Bessel interpolation within the nonuniform FFT (NUFFT) framework and devised ways of incorporation of resolution models into the Fourier-based iterative approaches. Numerical and computer simulation results show that the min-max NUFFT approach provides substantially lower approximation errors in tomographic forward and back-projection than conventional interpolation methods. Our studies have further confirmed that Fourier-based projectors using the NUFFT approach provide accurate approximations to their space-based counterparts but with about ten times faster computation, and that they are viable candidates for fast iterative image reconstruction.","Title: Accelerated Monotonic Algorithms for Transmission Tomography\nYear: 1998\n\nAbstract: We present a framework for designing fast and mono- tonic algorithms for transmission tomography penalized- likelihood image reconstruction. The new algorithms are based on paraboloidal surrogate functions for the log- likelihood. Due to the form of the log-likelihood func- tion, it is possible to find low curvature surrogate func- tions that guarantee monotonicity. Unlike previous meth- ods, the proposed surrogate functions lead to monotonic al- gorithms even for the nonconvex log- likelihood that arises due to background events such as scatter and random coin- cidences. The gradient and the curvature of the likelihood terms are evaluated only once per iteration. Since the prob- lem is simplified, the CPU time per iteration is less than that of current algorithms which directly minimize the ob- jective, yet the convergence rate is comparable. The sim- plicity, monotonicity and speed of the new algorithms are quite attractive. The convergence rates of the algorithms are demonstrated using real PET transmission scans. incidences in PET and emission crosstalk in SPECT. The assumption of no background counts can only be valid in X-ray CT. In this paper, we present an algorithm which is guaranteed to be monotonic even in the non-convex objec- tive function case. This algorithm depends on paraboloidal surrogate functions to the log-likelihood which transform the problem into a simpler optimization problem at each iteration. To obtain the paraboloid, we find 1-D parabolic functions that are tangent to and lie above each of the terms in the log-likelihood, similar to Huber's method for robust linear regression (3).","Title: Separate magnitude and phase regularization via compressed sensing.\nYear: 2012\n\nAbstract: Compressed sensing (CS) has been used for accelerating magnetic resonance imaging acquisitions, but its use in applications with rapid spatial phase variations is challenging, e.g., proton resonance frequency shift (PRF-shift) thermometry and velocity mapping. Previously, an iterative MRI reconstruction with separate magnitude and phase regularization was proposed for applications where magnitude and phase maps are both of interest, but it requires fully sampled data and unwrapped phase maps. In this paper, CS is combined into this framework to reconstruct magnitude and phase images accurately from undersampled data. Moreover, new phase regularization terms are proposed to accommodate phase wrapping and to reconstruct images with encoded phase variations, e.g., PRF-shift thermometry and velocity mapping. The proposed method is demonstrated with simulated thermometry data and in vivo velocity mapping data and compared to conventional phase corrected CS.","Title: Parallel MR image reconstruction using augmented Lagrangian methods.\nYear: 2011\n\nAbstract: Magnetic resonance image (MRI) reconstruction using SENSitivity Encoding (SENSE) requires regularization to suppress noise and aliasing effects. Edge-preserving and sparsity-based regularization criteria can improve image quality, but they demand computation-intensive nonlinear optimization. In this paper, we present novel methods for regularized MRI reconstruction from undersampled sensitivity en...","Title: A penalized-likelihood image reconstruction method for emission tomography, compared to postsmoothed maximum-likelihood with matched spatial resolution.\nYear: 2003\n\nAbstract: Regularization is desirable for image reconstruction in emission tomography. A powerful regularization method is the penalized-likelihood (PL) reconstruction algorithm (or equivalently, maximum a posteriori reconstruction), where the sum of the likelihood and a noise suppressing penalty term (or Bayesian prior) is optimized. Usually, this approach yields position-dependent resolution and bias. However, for some applications in emission tomography, a shift-invariant point spread function would be advantageous. Recently, a new method has been proposed, in which the penalty term is tuned in every pixel to impose a uniform local impulse response. In this paper, an alternative way to tune the penalty term is presented. We performed positron emission tomography and single photon emission computed tomography simulations to compare the performance of the new method to that of the postsmoothed maximum-likelihood (ML) approach, using the impulse response of the former method as the postsmoothing filter for the latter. For this experiment, the noise properties of the PL algorithm were not superior to those of postsmoothed ML reconstruction.","Title: Spatially-Variant Roughness Penalty Design for Uniform Resolution in Penalized-Likelihood Image Reconstruction\nYear: 1998\n\nAbstract: Traditional space-invariant regularization schemes in tomographic image reconstruction using penalized- likelihood estimators produce images with nonuniform resolution properties. The local point spread functions that quantify the local smoothing properties of such estimators are not only space-variant and asymmetric, but are also object-dependent even for space-invariant systems. We propose a new regularization scheme for increased spatial uniformity and demonstrate the resolution properties of this new method versus conventional regularization schemes through an investigation of local point spread functions.","Title: Relaxed ordered subsets algorithm for image restoration of confocal microscopy\nYear: 2002\n\nAbstract: The expectation-maximization (EM) algorithm for maximum-likelihood image recovery converges very slowly. Thus, the ordered subsets EM (OS-EM) algorithm has been widely used in image reconstruction for tomography due to an order-of-magnitude acceleration over the EM algorithm. However, OS-EM is not guaranteed to converge. The recently proposed ordered subsets, separable paraboloidal surrogates (OS-SPS) algorithm with relaxation has been shown to converge to the optimal point while providing fast convergence. In this paper, we develop a relaxed OS-SPS algorithm for image restoration. Because data acquisition is different in image restoration than in tomography, we adapt a different strategy for choosing subsets in image restoration which uses pixel location rather than projection angles. Simulation results show that the order-of-magnitude acceleration of the relaxed OS-SPS algorithm can be achieved in restoration. Thus the speed and the guarantee of the convergence of the OS algorithm is advantageous for image restoration as well.","Title: TWO STATE MARKOV MODELLING AND DETECTION OF SINGLE ELECTRON SPIN SIGNALS\nYear: 2004\n\nAbstract: The focus of this paper is the optimal detection of piecewise constant binary valued continuous-time (C-T) signals with Markovian state transitions. One example is the classic ran- dom telegraph signal for which the number of states is two and the transitions follow a Poisson process. This signal de- tection problem arises in many different areas of engineer- ing and science, notably modulation classification in digital communications and detection of digital content in continu- ous signals or images with high noise contamination. Our motivation is single electron-spin detection in Magnetic Res- onance Force Microscopy (MRFM), which is an emerging molecular scale imaging modality. We will obtain an optimal discrete time iterative detection algorithm and an associated upper bound on the Receiver Operating Characteristic (ROC) curve. These results will be used to show that the optimal detector reduces to a simple filtered energy detector when the state transition probabilities are symmetric, the signal- to-noise ratio (SNR) is low, and the time-bandwidth product is high. In the general case when the state transition proba- bilities can be either symmetric or asymmetric, the optimal detector reduces to a hybrid filtered energy/amplitude/energy detector when the SNR is low and there are a large number of samples per observation.","Title: Forward-Projection Architecture for Fast Iterative Image Reconstruction in X-Ray CT\nYear: 2012\n\nAbstract: Iterative image reconstruction can dramatically improve the image quality in X-ray computed tomography (CT), but the computation involves iterative steps of 3D forward- and back-projection, which impedes routine clinical use. To accelerate forward-projection, we analyze the CT geometry to identify the intrinsic parallelism and data access sequence for a highly parallel hardware architecture. To improve the efficiency of this architecture, we propose a water-filling buffer to remove pipeline stalls, and an out-of-order sectored processing to reduce the off-chip memory access by up to three orders of magnitude. We make a floating-point to fixed-point conversion based on numerical simulations and demonstrate comparable image quality at a much lower implementation cost. As a proof of concept, a 5-stage fully pipelined, 55-way parallel separable-footprint forward-projector is prototyped on a Xilinx Virtex-5 FPGA for a throughput of 925.8 million voxel projections/s at 200 MHz clock frequency, 4.6 times higher than an optimized 16-threaded program running on an 8-core 2.8-GHz CPU. A similar architecture can be applied to back-projection for a complete iterative image reconstruction system. The proposed algorithm and architecture can also be applied to hardware platforms such as graphics processing unit and digital signal processor to achieve significant accelerations.","Title: Efficient calculation of resolution and covariance for penalized-likelihood reconstruction in fully 3-D SPECT\nYear: 2004\n\nAbstract: Resolution and covariance predictors have been derived previously for penalized-likelihood estimators. These predictors can provide accurate approximations to the local resolution properties and covariance functions for tomographic systems given a good estimate of the mean measurements. Although these predictors may be evaluated iteratively, circulant approximations are often made for practical co...","Title: Fast, Iterative Image Reconstruction for MRI in the Presence of Field Inhomogeneities.\nYear: 2003\n\nAbstract: In magnetic resonance imaging, magnetic field inhomogeneities cause distortions in images that are reconstructed by conventional fast Fourier transform (FFT) methods. Several noniterative image reconstruction methods are used currently to compensate for field inhomogeneities, but these methods assume that the field map that characterizes the off-resonance frequencies is spatially smooth. Recently,...","Title: Motion Correction in fMRI by Mapping Slice-to-Volume with Concurrent Field-Inhomogeneity Correction\nYear: 2004\n\nAbstract: Head motion is the major source of error in measuring intensity changes related to given stimuli in fMRI. The effects of head motion are image shifts and field inhomogeneity variations which cause local changes in geometric distortions. The previously developed motion correction method, mapping slice-to-volume (MSV), retrospectively remaps slices that are shifted by head motion to their spatially correct locations in an anatomical reference. Images exhibiting spatially varying geometric distortions require non-linear mapping solutions. An accurate field map can be used for the correction of such spatial distortions. However, field-map changes with head motion and, in practice, only one field-map is available typically. This work evaluates the improved motion correction capability of MSV with concurrent iterative field-corrected reconstruction using only an initial field-map. The results from simulated motion data show effective convergence and accuracy in image registration for the correction of image artifacts complicated by the motion induced field effects.","Title: Space-alternating generalized expectation-maximization algorithm\nYear: 1994\n\nAbstract: The expectation-maximization (EM) method can facilitate maximizing likelihood functions that arise in statistical estimation problems. In the classical EM paradigm, one iteratively maximizes the conditional log-likelihood of a single unobservable complete data space, rather than maximizing the intractable likelihood function for the measured or incomplete data. EM algorithms update all parameters simultaneously, which has two drawbacks: 1) slow convergence, and 2) difficult maximization steps due to coupling when smoothness penalties are used. The paper describes the space-alternating generalized EM (SAGE) method, which updates the parameters sequentially by alternating between several small hidden-data spaces defined by the algorithm designer. The authors prove that the sequence of estimates monotonically increases the penalized-likelihood objective, derive asymptotic convergence rates, and provide sufficient conditions for monotone convergence in norm. Two signal processing applications illustrate the method: estimation of superimposed signals in Gaussian noise, and image reconstruction from Poisson measurements. In both applications, the SAGE algorithms easily accommodate smoothness penalties and converge faster than the EM algorithms","Title: Nonparametric fixed-interval smoothing with vector splines\nYear: 1991\n\nAbstract: A computationally efficient algorithm for nonparametric smoothing of vector signals with general measurement covariances is presented. This algorithm provides an alternative to the optimal smoothing algorithms that hinge on (possibly inaccurate) parametric state-space models. Automatic procedures that use the measurements to determine how much to smooth are developed and compared. This adaptation allows the data to speak for itself without imposing a Gauss-Markov model structure. A nonparametric approach to covariance estimation for the case of independently identically distributed (i.i.d.) measurement errors is presented. Monte Carlo simulations demonstrate the performance of the algorithm","Title: Maximum-likelihood dual-energy tomographic image reconstruction\nYear: 2002\n\nAbstract: Dual-energy (DE) X-ray computed tomography (CT) has shown promise for material characterization and for providing quantitatively accurate CT values in a variety of applications. However, DE-CT has not been used routinely in medicine to date, primarily due to dose considerations. Most methods for DE-CT have used the filtered backprojection method for image reconstruction, leading to suboptimal noise/dose properties. This paper describes a statistical (maximum-likelihood) method for dual-energy X-ray CT that accommodates a wide variety of potential system configurations and measurement noise models. Regularized methods (such as penalized-likelihood or Bayesian estimation) are straightforward extensions. One version of the algorithm monotonically decreases the negative log-likelihood cost function each iteration. An ordered-subsets variation of the algorithm provides a fast and practical version.","Title: Model-based estimation techniques for 3-D reconstruction from projections\nYear: 1988\n\nAbstract: A parametric estimation approach to reconstruction from projections with incomplete and very noisy data is described. Embedding prior knowledge about “objects” in the probed domain and about the data acquisition process into stochastic dynamic models, we transform the reconstruction problem into a computationally challenging nonlinear state-estimation problem, where the objects' parametrized descriptions are to be directly estimated from the projection data. This paper is a review in a common framework and a comparative study of two distinct algorithms which were developed recently for the solution of this problem. The first, is an approximate, globally optimal minimum-meansquare-error recursive algorithm. The second is a hierarchical suboptimal Bayesian algorithm. Simulation examples demonstrate accurate reconstructions with as few as four views in a 135° sector, at an average signal to noise ratio of 0.6.","Title: Regularized image reconstruction algorithms for dual-isotope myocardial perfusion SPECT (MPS) imaging using a cross-tracer prior.\nYear: 2011\n\nAbstract: In simultaneous dual-isotope myocardial perfusion SPECT (MPS) imaging, data are simultaneously acquired to determine the distributions of two radioactive isotopes. The goal of this work was to develop penalized maximum likelihood (PML) algorithms for a novel cross-tracer prior that exploits the fact that the two images reconstructed from simultaneous dual-isotope MPS projection data are perfectly registered in space. We first formulated the simultaneous dual-isotope MPS reconstruction problem as a joint estimation problem. A cross-tracer prior that couples voxel values on both images was then proposed. We developed an iterative algorithm to reconstruct the MPS images that converges to the maximum a posteriori solution for this prior based on separable surrogate functions. To accelerate the convergence, we developed a fast algorithm for the cross-tracer prior based on the complete data OS-EM (COSEM) framework. The proposed algorithm was compared qualitatively and quantitatively to a single-tracer version of the prior that did not include the cross-tracer term. Quantitative evaluations included comparisons of mean and standard deviation images as well as assessment of image fidelity using the mean square error. We also evaluated the cross tracer prior using a three-class observer study with respect to the three-class MPS diagnostic task, i.e., classifying patients as having either no defect, reversible defect, or fixed defects. For this study, a comparison with conventional ordered subsets-expectation maximization (OS-EM) reconstruction with postfiltering was performed. The comparisons to the single-tracer prior demonstrated similar resolution for areas of the image with large intensity changes and reduced noise in uniform regions. The cross-tracer prior was also superior to the single-tracer version in terms of restoring image fidelity. Results of the three-class observer study showed that the proposed cross-tracer prior and the convergent algorithms improved the image quality of dual-isotope MPS images compared to OS-EM.","Title: Tomographic Reconstruction Using Information-Weighted Spline Smoothing\nYear: 1993\n\nAbstract: The conventional method for tomographic image reconstruction, convolution backprojection (CBP), attempts to reduce the effects of measurement noise by radial smoothing with a spatially-invariant filter. Spatially-invariant smoothing is suboptimal when the measurement statistics are nonstationary, and often leads to a choice between oversmoothing or streak artifacts. In this paper, we describe a nonstationary sinogram smoothing method that ac- counts for the relative variances between different detector measurements and for the finite width of tomographic detectors. The method is based on an information-weighted smoothing spline, where the weights are determined from the calibration factors and from the measurements themselves. This weighting diminishes the influence of high variance measurements, such as detectors with relatively poor efficiency, which is shown to reduce streak artifacts. Simulations of emission and transmission tomography applications demonstrate qualitatively improved image noise structure and quantitative improvements in the tradeoffs between bias and variance.","Title: Quadratic regularization design for fan beam transmission tomography\nYear: 2005\n\nAbstract: Statistical methods for tomographic image reconstruction have shown considerable potential for improving image quality in X-ray CT. Penalized-likelihood (PL) image reconstruction methods require maximizing an objective function that is based on the log-likelihood of the sinogram measurements and on a roughness penalty I unction to control noise. In transmission tomography, PL methods (and MAP methods) based on conventional quadratic regularization functions lead to nonuniform and anisotropic spatial resolution, even for idealized shift-invariant imaging systems. We have previously addressed this problem for parallel-beam emission tomography by designing data-dependent, shift-variant regularizers that improve resolution uniformity. This paper extends those methods to the fan-beam geometry used in X-ray CT imaging Simulation results demonstrate that the new method for regularization design requires very modest computation and leads to nearly uniform and isotropic spatial resolution in the fan-beam geometry when using quadratic regularization.","Title: Regularized methods for topology-preserving smooth nonrigid image registration using B-spline basis\nYear: 2008\n\nAbstract: B-splines are a convenient tool for nonrigid registration, but ensuring invertibility can be challenge. This paper describes a new penalty method that is devised to enforce a sufficient condition for local invertibility and smoothness of nth order B-spline based deformations. Traditional direct Jacobian penalty methods penalize negative Jacobian determinant values only at grid points. In contrast, our new penalty method enforces the sufficient condition for invertibility directly on the B-spline coefficients by using a modified quadratic penalty function so that it enforces invertibility globally over a 3D continuous domain. This approach also saves computation time and memory compared to using Jacobian determinant values. We apply this method to 3D CT images of a thorax at inhale and exhale.","Title: Fast Predictions of Variance Images for Fan-Beam Transmission Tomography With Quadratic Regularization.\nYear: 2007\n\nAbstract: Accurate predictions of image variances can be useful for reconstruction algorithm analysis and for the design of regularization methods. Computing the predicted variance at every pixel using matrix-based approximations [1] is impractical. Even most recently adopted methods that are based on local discrete Fourier approximations are impractical since they would require a forward and backprojection and two fast Fourier transform (FFT) calculations for every pixel, particularly for shift-variant systems like fan-beam tomography. This paper describes new \"analytical\" approaches to predicting the approximate variance maps of 2-D images that are reconstructed by penalized-likelihood estimation with quadratic regularization in fan-beam geometries. The simplest of the proposed analytical approaches requires computation equivalent to one backprojection and some summations, so it is computationally practical even for the data sizes in X-ray computed tomography (CT). Simulation results show that it gives accurate predictions of the variance maps. The parallel-beam geometry is a simple special case of the fan-beam analysis. The analysis is also applicable to 2-D positron emission tomography (PET).","Title: Convergent incremental optimization transfer algorithms: application to tomography.\nYear: 2006\n\nAbstract: No convergent ordered subsets (OS) type image reconstruction algorithms for transmission tomography have been proposed to date. In contrast, in emission tomography, there are two known families of convergent OS algorithms: methods that use relaxation parameters, and methods based on the incremental expectation-maximization (EM) approach. This paper generalizes the incremental EM approach by introducing a general framework, \"incremental optimization transfer.\" The proposed algorithms accelerate convergence speeds and ensure global convergence without requiring relaxation parameters. The general optimization transfer framework allows the use of a very broad family of surrogate functions, enabling the development of new algorithms. This paper provides the first convergent OS-type algorithm for (nonconcave) penalized-likelihood (PL) transmission image reconstruction by using separable paraboloidal surrogates (SPS) which yield closed-form maximization steps. We found it is very effective to achieve fast convergence rates by starting with an OS algorithm with a large number of subsets and switching to the new \"transmission incremental optimization transfer (TRIOT)\" algorithm. Results show that TRIOT is faster in increasing the PL objective than nonincremental ordinary SPS and even OS-SPS yet is convergent.","Title: Dynamic Mr Image And Fieldmap Joint Reconstruction Accounting For Through-Plane Fieldmap Gradients\nYear: 2011\n\nAbstract: In susceptibility-weighted MRI, ignoring the magnetic field inhomogeneity can lead to severe reconstruction artifacts. Correcting for the effects of magnetic field inhomogeneity requires accurate fieldmaps. Especially in functional MRI, dynamic updates are desirable, since the fieldmap may change in time. Also, susceptibility effects that induce field inhomogeneity often have non-zero through-plane gradients, which, if uncorrected, can cause signal loss in the reconstructed images. Most image reconstruction methods that compensate for field inhomogeneity, even using dynamic fieldmap updates, ignore through-plane fieldmap gradients. This work proposes a computationally efficient, model based iterative method for joint reconstruction of image and dynamic fieldmap that accounts for the through-plane gradients of the field inhomogeneity. The proposed method allows for efficient reconstruction by applying fast approximations that allow the use of the conjugate gradient algorithm along with FFTs.","Title: Reducing between scanner differences in multi-center PET studies.\nYear: 2009\n\nAbstract: This work is part of the multi-center Alzheimer's Disease Neuroimaging Initiative (ADNI), a large multi-site study of dementia, including patients having mild cognitive impairment (MCI), probable Alzheimer's disease (AD), as well as healthy elderly controls. A major portion of ADNI involves the use of [18F]-fluorodeoxyglucose (FDG) with positron emission tomography (PET). The objective of this paper is the reduction of inter-scanner differences in the FDG-PET scans obtained from the 50 participating PET centers having fifteen different scanner models. In spite of a standardized imaging protocol, systematic inter-scanner variability in PET images from various sites is observed primarily due to differences in scanner resolution, reconstruction techniques, and different implementations of scatter and attenuation corrections. Two correction steps were developed by comparison of 3-D Hoffman brain phantom scans with the ‘gold standard’ digital 3-D Hoffman brain phantom: i) high frequency correction; where a smoothing kernel for each scanner model was estimated to smooth all images to a common resolution and ii) low frequency correction; where smooth affine correction factors were obtained to reduce the attenuation and scatter correction errors. For the phantom data, the high frequency correction reduced the variability by 20%–50% and the low frequency correction further reduced the differences by another 20%–25%. Correction factors obtained from phantom studies were applied to 95 scans from normal control subjects obtained from the participating sites. The high frequency correction reduced differences similar to the phantom studies. However, the low frequency correction did not further reduce differences; hence further refinement of the procedure is necessary.","Title: Emission image reconstruction for randoms-precorrected PET allowing negative sinogram values.\nYear: 2004\n\nAbstract: Most positron emission tomography (PET) emission scans are corrected for accidental coincidence (AC) events by real-time subtraction of delayed-window coincidences, leaving only the randoms-precorrected data available for image reconstruction. The real-time randoms precorrection compensates in mean for AC events but destroys the Poisson statistics. The exact log-likelihood for randoms-precorrected data is inconvenient, so practical approximations are needed for maximum likelihood or penalized-likelihood image reconstruction. Conventional approximations involve setting negative sinogram values to zero, which can induce positive systematic biases, particularly for scans with low counts per ray. We propose new likelihood approximations that allow negative sinogram values without requiring zero-thresholding. With negative sinogram values, the log-likelihood functions can be nonconcave, complicating maximization; nevertheless, we develop monotonic algorithms for the new models by modifying the separable paraboloidal surrogates and the maximum-likelihood expectation-maximization (ML-EM) methods. These algorithms ascend to local maximizers of the objective function. Analysis and simulation results show that the new shifted Poisson (SP) model is nearly free of systematic bias yet keeps low variance. Despite its simpler implementation, the new SP performs comparably to the saddle-point model which has shown the best performance (as to systematic bias and variance) in randoms-precorrected PET emission reconstruction.","Title: Regularization Parameter Selection for Nonlinear Iterative Image Restoration and MRI Reconstruction Using GCV and SURE-Based Methods\nYear: 2012\n\nAbstract: Regularized iterative reconstruction algorithms for imaging inverse problems require selection of appropriate regularization parameter values. We focus on the challenging problem of tuning regularization parameters for nonlinear algorithms for the case of additive (possibly complex) Gaussian noise. Generalized cross-validation (GCV) and (weighted) mean-squared error (MSE) approaches [based on Stein's unbiased risk estimate (SURE)] need the Jacobian matrix of the nonlinear reconstruction operator (representative of the iterative algorithm) with respect to the data. We derive the desired Jacobian matrix for two types of nonlinear iterative algorithms: a fast variant of the standard iterative reweighted least-squares method and the contemporary split-Bregman algorithm, both of which can accommodate a wide variety of analysis- and synthesis-type regularizers. The proposed approach iteratively computes two weighted SURE-type measures: predicted-SURE and projected-SURE (which require knowledge of noise variance $\\sigma^{2}$), and GCV (which does not need $\\sigma^{2}$) for these algorithms. We apply the methods to image restoration and to magnetic resonance image (MRI) reconstruction using total variation and an analysis-type $\\ell_{1}$-regularization. We demonstrate through simulations and experiments with real data that minimizing predicted-SURE and projected-SURE consistently lead to near-MSE-optimal reconstructions. We also observe that minimizing GCV yields reconstruction results that are near-MSE-optimal for image restoration and slightly suboptimal for MRI. Theoretical derivations in this paper related to Jacobian matrix evaluations can be extended, in principle, to other types of regularizers and reconstruction algorithms.","Title: Grouped-Coordinate Ascent Algorithms for Penalized-Likelihood Transmission Image Reconstruction\nYear: 1997\n\nAbstract: Presents a new class of algorithms for penalized-likelihood reconstruction of attenuation maps from low-count transmission scans. We derive the algorithms by applying to the transmission log-likelihood a version of the convexity technique developed by De Pierro for emission tomography. The new class includes the single-coordinate ascent (SCA) algorithm and Lange's convex algorithm for transmission...","Title: Maximum Likelihood Transmission Image Reconstruction for Overlapping Transmission Beams\nYear: 2000\n\nAbstract: In many transmission imaging geometries, the transmitted "beams" of photons overlap on the detector, such that a detector element may record photons that originated in different sources or source locations and thus traversed different paths through the object. Examples include systems based on scanning line sources or on multiple parallel rod sources. The overlap of these beams has been disregarde...","Title: Regularized Field Map Estimation in MRI.\nYear: 2008\n\nAbstract: In fast magnetic resonance (MR) imaging with long readout times, such as echo-planar imaging (EPI) and spiral scans, it is important to correct for the effects of field inhomogeneity to reduce image distortion and blurring. Such corrections require an accurate field map, a map of the off-resonance frequency at each voxel. Standard field map estimation methods yield noisy field maps, particularly i...","Title: A Simple Regularizer for B-spline Nonrigid Image Registration That Encourages Local Invertibility.\nYear: 2009\n\nAbstract: Non rigid image registration is an important task for many medical imaging applications. In particular, for radiation oncology it is desirable to track respiratory motion for thoracic cancer treatment. B-splines are convenient for modeling nonrigid deformations, but ensuring invertibility can be a challenge. This paper describes sufficient conditions for local invertibility of deformations based on B-spline bases. These sufficient conditions can be used with constrained optimization to enforce local invertibility. We also incorporate these conditions into nonrigid image registration methods based on a simple penalty approach that encourages diffeomorphic deformations. Traditional Jacobian penalty methods penalize negative Jacobian determinant values only at grid points. In contrast, our new method enforces a sufficient condition for invertibility directly on the deformation coefficients to encourage invertibility globally over a 3-D continuous domain. The proposed penalty approach requires substantially less compute time than Jacobian penalties per iteration.","Title: Intensity-based image registration using robust correlation coefficients.\nYear: 2004\n\nAbstract: The ordinary sample correlation coefficient is a popular similarity measure for aligning images from the same or similar modalities. However, this measure can be sensitive to the presence of "outlier" objects that appear in one image but not the other, such as surgical instruments, the patient table, etc., which can lead to biased registrations. This paper describes an intensity-based image regist...","Title: Fast Large-Tip-Angle Multidimensional and Parallel RF Pulse Design in MRI.\nYear: 2009\n\nAbstract: Large-tip-angle multidimensional radio-frequency (RF) pulse design is a difficult problem, due to the nonlinear response of magnetization to applied RF at large tip-angles. In parallel excitation, multidimensional RF pulse design is further complicated by the possibility for transmit field patterns to change between subjects, requiring pulses to be designed rapidly while a subject lies in the scanner. To accelerate pulse design, we introduce a fast version of the optimal control method for large-tip-angle parallel excitation. The new method is based on a novel approach to analytically linearizing the Bloch equation about a large-tip-angle RF pulse, which results in an approximate linear model for the perturbations created by adding a small-tip-angle pulse to a large-tip-angle pulse. The linear model can be evaluated rapidly using nonuniform fast Fourier transforms, and we apply it iteratively to produce a sequence of pulse updates that improve excitation accuracy. We achieve drastic reductions in design time and memory requirements compared to conventional optimal control, while producing pulses of similar accuracy. The new method can also compensate for nonidealities such as main field inhomogeneties.","Title: Joint Estimation Of Respiratory Motion And Activity In 4d Pet Using Ct Side Information\nYear: 2006\n\nAbstract: In previous work, we proposed a Poisson statistical model for gated PET data in which the distribution was parametrized in terms of both image intensity and motion parameters. The motion parameters related the activity image in each gate to that of a base image in some fixed gate. By doing maximum loglikelihood (ML) estimation of all parameters simultaneously, one obtains an estimate of the base gate image that exploits the full set of measured sinogram data. Previously, this joint ML approach was compared, in a highly simplified single-slice setting, to more conventional methods. Performance was measured in terms of the recovery of tracer uptake in a synthetic lung nodule. This paper reports the extension to 3D with much more realistic simulated motion. Furthermore, in addition to pure ML estimation, we consider the use of side information from a breath-hold CT scan to facilitate regularization, while preserving hot lesions of the kind seen in FDG oncology studies.","Title: Statistical sinogram restoration in dual-energy CT for PET attenuation correction.\nYear: 2009\n\nAbstract: Dual-energy (DE) X-ray computed tomography (CT) has been found useful in various applications. In medical imaging, one promising application is using low-dose DECT for attenuation correction in positron emission tomography (PET). Existing approaches to sinogram material decomposition ignore noise characteristics and are based on logarithmic transforms, producing noisy component sinogram estimates ...","Title: Ordered subsets with momentum for accelerated X-ray CT image reconstruction\nYear: 2013\n\nAbstract: Statistical image reconstruction methods provide improved image quality in low-dose X-ray CT. However, the long computation time of iterative algorithms limits their clinical use. Ordered subsets algorithms based on separable quadratic surrogates (OS-SQS) are attractive as they are simple and amenable for massive parallelization in modern computing architecture, but require many iterations to converge. Here, we further accelerate OS algorithms by using momentum techniques. We use real patient CT scan to illustrate that the proposed algorithms converge rapidly compared to previous OS algorithms.","Title: Image registration using robust correlation\nYear: 2002\n\nAbstract: We have investigated an intensity-based image registration technique using a robust correlation coefficient as a similarity measure. The proposed method has an advantage over the ordinary correlation coefficient since it reduces the effect of \"outlier\" image intensity values. For the application of image registration to radiotherapy or image-guided surgery, there may be outlier samples due to the presence of the objects such as surgical instruments. We have verified the usefulness of the proposed method by simulation and phantom experiment.","Title: Correction for Collimator-Detector Response in SPECT Using Point Spread Function Template\nYear: 2013\n\nAbstract: Compensating for the collimator-detector response (CDR) in SPECT is important for accurate quantification. The CDR consists of both a geometric response and a septal penetration and collimator scatter response. The geometric response can be modeled analytically and is often used for modeling the whole CDR if the geometric response dominates. However, for radionuclides that emit medium or high-energy photons such as I-131, the septal penetration and collimator scatter response is significant and its modeling in the CDR correction is important for accurate quantification. There are two main methods for modeling the depth-dependent CDR so as to include both the geometric response and the septal penetration and collimator scatter response. One is to fit a Gaussian plus exponential function that is rotationally invariant to the measured point source response at several source-detector distances. However, a rotationally-invariant exponential function cannot represent the star-shaped septal penetration tails in detail. Another is to perform Monte-Carlo (MC) simulations to generate the depth-dependent point spread functions (PSFs) for all necessary distances. However, MC simulations, which require careful modeling of the SPECT detector components, can be challenging and accurate results may not be available for all of the different SPECT scanners in clinics. In this paper, we propose an alternative approach to CDR modeling. We use a Gaussian function plus a 2-D B-spline PSF template and fit the model to measurements of an I-131 point source at several distances. The proposed PSF-template-based approach is nearly non-parametric, captures the characteristics of the septal penetration tails, and minimizes the difference between the fitted and measured CDR at the distances of interest. The new model is applied to I-131 SPECT reconstructions of experimental phantom measurements, a patient study, and a MC patient simulation study employing the XCAT phantom. The proposed model yi- lds up to a 16.5 and 10.8% higher recovery coefficient compared to the results with the conventional Gaussian model and the Gaussian plus exponential model, respectively.","Title: Fast Interpolation Operations in Non-Rigid Image Registration\nYear: 2005\n\nAbstract: Much literature on image registration(1-3) has worked with purely geometric image deformation models. For such models, interpolation/resampling operations are often the computationally intensive steps when iteratively minimizing the deformation cost function. This article discusses some techniques for efficiently implementing and accelerating these operations. To simplify presentation, we discuss our ideas in the context of 2D imaging. However, the concepts readily generalize to 3D. Our central technique is a table-lookup scheme that makes somewhat liberal use of RAM, but should not strain the resources of modern processors if certain design parameters are appropriately selected. The technique works by pre-interpolating and tabulating the grid values of the reference image onto a finer grid along one of the axes of the image. The lookup table can be rapidly constructed using FFTs. Our results show that this technique reduces iterative computation by an order of magnitude. When a minimization algorithm employing coordinate block alternation is used, one can obtain still faster computation by storing certain intermediate quantities as state variables. We refer to this technique as state variable hold-over. When combined with table-lookup, state variable hold-over reduces CPU time by about a factor two, as compared to table-lookup alone.","Title: Incorporating Mri Region Information Into Spect Reconstruction Using Joint Estimation\nYear: 1995\n\nAbstract: Single Photon Emission Computed Tomographic images(SPECT) have relatively poor resolution. In an attemptto improve SPECT image quality, many methodshave been developed for including anatomic information,extracted from higher resolution, structurally correlated MagneticResonance images(MRI), into SPECT reconstructionprocess. These methods provide improved SPECT reconstructionaccuracy if the anatomic information is perfectlycorrelated with the SPECT functional information. Howeverthere...","Title: Model-based image reconstruction for dual-energy X-ray CT with fast KVP switching\nYear: 2009\n\nAbstract: The most recent generation of X-ray CT systems can collect dual energy (DE) sinograms by rapidly switching the X-ray tube voltage between two levels for alternate projection views. This reduces motion artifacts in DE imaging, but yields sinograms that may be angularly under-sampled. This paper describes an iterative algorithm for statistical image reconstruction of material component images (e.g., soft tissue and bone) directly from such under-sampled DE data, without resorting to the interpolation operations required by conventional DE reconstruction methods.","Title: ALGORITHMS FOR AREA PRESERVING FLOWS.\nYear: 2011\n\nAbstract: We propose efficient and accurate algorithms for computing certain area preserving geometric motions of curves in the plane, such as area preserving motion by curvature. These schemes are based on a new class of diffusion generated motion algorithms using signed distance functions. In particular, they alternate two very simple and fast operations, namely convolution with the Gaussian kernel and construction of the distance function, to generate the desired geometric flow in an unconditionally stable manner. We present applications of these area preserving flows to large scale simulations of coarsening.","Title: Sufficient condition for local invertibility of spatio-temporal 4D B-spline deformations\nYear: 2010\n\nAbstract: Recent advances in medical imaging technologies have made 4D image sequences available in clinical routine. As a consequence, image registration techniques are evolving from alignment of pairs of static volumetric images to spatio-temporal registration of dynamic (4D) images. Since the elastic image registration problem is ill-posed, additional prior information or constraints are usually required to regularize the problem. This work proposes to enforce local invertibility (diffeomorphism) of 4D deformations. A novel sufficient condition for local invertibility over continuous space and time is proposed and a practical regularization prior is designed from the theory. The method has been applied to an image registration (motion tracking) of a dynamic 4D CT image sequence. Results show that using proposed regularizer leads to deformations that are more plausible for respiratory motion than the standard approach without additional temporal regularization.","Title: Accelerated Ordered-Subsets Algorithm Based On Separable Quadratic Surrogates For Regularized Image Reconstruction In X-Ray Ct\nYear: 2011\n\nAbstract: Iterative algorithms for X-ray CT image reconstruction offer the possibility of reduced dose and/or improved image quality, but require substantial compute time. Reducing the time will likely require algorithms that can be massively parallelized. Ordered subsets (OS) algorithms update all voxels simultaneously and thus are amenable to such parallelization. We present an new monotonic algorithm for regularized image reconstruction that is derived using optimization transfer with separable quadratic surrogates (SQS). The new algorithm accelerates the convergence rate by adapting reduced curvature values for the regularizer that were proposed by Yu et al. [1] for coordinate descent algorithms. We further accelerate the algorithm using ordered subsets. Simulation results show that the proposed OS algorithm converges faster than the traditional OS algorithm for X-ray CT reconstruction from a limited number of projection views.","Title: Fast Monotonic Algorithms for Transmission Tomography\nYear: 1999\n\nAbstract: We present a framework for designing fast and monotonic algorithms for transmission tomography penalized- likelihood image reconstruction. The new algorithms are based on paraboloidal surrogate functions for the log likelihood. Due to the form of the log-likelihood function it is possible to find low curvature surrogate functions that guarantee monotonicity. Unlike previous methods, the proposed surrogate functions lead to monotonic algorithms even for the nonconvex log likelihood that arises due to background events, such as scatter and random coincidences. The gradient and the curvature of the likelihood terms are evaluated only once per iteration. Since the problem is simplified at each iteration, the CPU time is less than that of current algorithms which directly minimize the objective, yet the convergence rate is comparable. The simplicity, monotonic- ity, and speed of the new algorithms are quite attractive. The convergence rates of the algorithms are demonstrated using real and simulated PET transmission scans.","Title: Spatial resolution and noise properties of regularized motion-compensated image reconstruction\nYear: 2009\n\nAbstract: Reducing motion artifacts is an important problem in medical image reconstruction. Using gating to partition data into separate frames can reduce motion artifacts but can increase noise in images reconstructed fromindividual frames. One can pool the frames to reduce noise by using motion-compensated image reconstruction (MCIR) methods. MCIR methods have been studied in many medical imaging modalities to reduce both noise and motion artifacts. However, there has been less analysis of the spatial resolution and noise properties of MCIR methods. This paper analyzes the spatial resolution and noise properties of MCIR methods based on a general parametric motion model. For simplicity we consider the motion to be given. We present a method to choose quadratic spatial regularization parameters to provide predictable resolution properties that are independent of the object and the motion. The noise analysis shows that the estimator variance depends on both the measurement covariance and the Jacobian determinant values of the motion. A 2D PET simulation demonstrates the theoretical results.","Title: Iterative image reconstruction for dual-energy X-ray CT using regularized material sinogram estimates.\nYear: 2011\n\nAbstract: X-ray CT images have various applications, including CT-based attenuation correction (CTAC) for PET. Low-dose CT imaging is particularly desirable for CTAC. Dual-energy (DE) CT imaging methods may improve the accuracy of attenuation correction in PET. However, conventional DE CT approaches to sinogram material decomposition use logarithmic transforms that are sensitive to noise in low-dose scans. This paper describes a DE reconstruction method based on statistical models that avoids using a logarithm. We first estimate material sinograms directly from the raw DE data (without any logarithm), with mild regularization to control noise and avoid outliers. We then apply a penalized weighted least squares (PWLS) method to reconstruct images of the two material components. We also propose a joint edge-preserving regularizer that uses the prior knowledge that the two material images have many region edges located in the same positions. Preliminary simulation results suggest that this iterative method improves image quality compared to conventional approaches based on log data for low-dose DE CT scans.","Title: Motion Robust Magnetic Susceptibility and Field Inhomogeneity Estimation Using Regularized Image Restoration Techniques for fMRI\nYear: 2008\n\nAbstract: In functional MRI, head motion may cause dynamic nonlinear field-inhomogeneity changes, especially with large out-of-plane rotations. This may lead to dynamic geometric distortion or blurring in the time series, which may reduce activation detection accuracy. The use of image registration to estimate dynamic field inhomogeneity maps from a static field map is not sufficient in the presence of such rotations. This paper introduces a retrospective approach to estimate magnetic susceptibility induced field maps of an object in motion, given a static susceptibility induced field map and the associated object motion parameters. It estimates a susceptibility map from a static field map using regularized image restoration techniques, and applies rigid body motion to the former. The dynamic field map is then computed using susceptibility voxel convolution. The method addresses field map changes due to out-of-plane rotations during time series acquisition and does not involve real time field map acquisitions.","Title: Analysis Of Unknown-Location Signal Detectability For Regularized Tomographic Image Reconstruction\nYear: 2006\n\nAbstract: Our goal is to optimize regularized image reconstruction methods for emission tomography with respect to the task of detecting small lesions of unknown location in the reconstructed images. We consider model observers whose decisions are based on finding the maximum value of a local test statistic over all possible lesion locations. We use tail probability approximations by Adler (AAP 2000) and Siegmund and Worsley (AS 1995) to evaluate the probabilities of false alarm and detection respectively for the observers of interest. We illustrate how these analytical tools can be used to optimize regularization with respect to the performance (at low probability of false alarm operating points) of a maximum channelized non-prewhitening observer.","Title: Fourier-based forward and back-projectors in iterative fan-beam tomographic image reconstruction.\nYear: 2004\n\nAbstract: Fourier-based forward and back-projection methods can reduce computation in iterative tomographic image reconstruction. Recently, an optimized nonuniform fast Fourier transform (NUFFT) approach was shown to yield accurate parallel-beam projections. In this paper, we extend the NUFFT approach to describe an O (N2 log N) projector/backprojector pair for fan-beam transmission tomography. Simulations and experiments with real CT data show that fan-beam Fourier-based forward and back-projection methods can reduce computation for iterative reconstruction while still providing accuracy comparable to their O (N3) space-based counterparts.","Title: Statistical Image Reconstruction for Polyenergetic X-ray Computer Tomography\nYear: 2002\n\nAbstract: This paper describes a statistical image reconstruction method for X-ray computed tomography (CT) that is based on a physical model that accounts for the polyenergetic X-ray source spectrum and the measurement nonlinearities caused by energy-dependent attenuation. We assume that the object consists of a given number of nonoverlapping materials, such as soft tissue and bone. The attenuation coeffic...","Title: 3D forward and back-projection for X-ray CT using separable footprints.\nYear: 2010\n\nAbstract: Iterative methods for 3D image reconstruction have the potential to improve image quality over conventional filtered back projection (FBP) in X-ray computed tomography (CT). However, the computation burden of 3D cone-beam forward and back-projectors is one of the greatest challenges facing practical adoption of iterative methods for X-ray CT. Moreover, projector accuracy is also important for iterative methods. This paper describes two new separable footprint (SF) projector methods that approximate the voxel footprint functions as 2D separable functions. Because of the separability of these footprint functions, calculating their integrals over a detector cell is greatly simplified and can be implemented efficiently. The SF-TR projector uses trapezoid functions in the transaxial direction and rectangular functions in the axial direction, whereas the SF-TT projector uses trapezoid functions in both directions. Simulations and experiments showed that both SF projector methods are more accurate than the distance-driven (DD) projector, which is a current state-of-the-art method in the field. The SF-TT projector is more accurate than the SF-TR projector for rays associated with large cone angles. The SF-TR projector has similar computation speed with the DD projector and the SF-TT projector is about two times slower.","Title: Penalized Likelihood Transmission Image Reconstruction: Unconstrained Monotonic Algorithms\nYear: 2004\n\nAbstract: Statistical reconstruction algorithms in transmission tomography yield improved images relative to the conventional FBP method. The most popular iterative algorithms for this problem are the conjugate gradient (CG) method and ordered subsets (OS) methods. Neither method is ideal. OS methods \"converge\" quickly, but are suboptimal for problems with factored system matrices. Nonnegativity constraints are not imposed easily by the CG method. To speed convergence, we propose to abandon the nonnegativity constraints (letting the regularization discourage the negative values), and to use quadratic surrogates to choose the step size rather than using an expensive line search. To ensure monotonicity, we develop a modification of the transmission log-likelihood. The resulting algorithm is suitable for large-scale problems with factored system matrices such as X-ray CT image reconstruction with afterglow models. Preliminary results show that the regularization ensures minimal negative values, and that the algorithm is indeed monotone.","Title: Model-based estimation with boundary side information or boundary regularization [cardiac emission CT]\nYear: 1994\n\nAbstract: We have previously developed a model-based strategy for joint estimation of myocardial perfusion and boundaries using ECT (Emission Computed Tomography). We have also reported difficulties with boundary estimation in low contrast and low count rate situations. In this paper, we propose using boundary side information (obtainable from high resolution MRI and CT images) or boundary regularization to improve both perfusion and boundary estimation in these situations. To fuse boundary side information into the emission measurements, we formulate a joint log-likelihood function to include auxiliary boundary measurements as well as ECT projection measurements. In addition, we introduce registration parameters to align auxiliary boundary measurements with ECT measurements and jointly estimate these parameters with other parameters of interest from the composite measurements. In simulated PET 0-15 water myocardial perfusion studies using a simplified model, we show that the joint estimation improves perfusion estimation performance and gives boundary alignment accuracy of <0.5 mm even at 0.2 million counts. We implement boundary regularization through formulating a penalized log-likelihood function. We also demonstrate in simulations that simultaneous regularization of the epicardial boundary and myocardial thickness gives comparable perfusion estimation accuracy with the use of boundary side information.","Title: Hardware Acceleration Of Iterative Image Reconstruction For X-Ray Computed Tomography\nYear: 2011\n\nAbstract: X-ray computed tomography (CT) images could be improved using iterative image reconstruction if the 3D cone-beam forward-and back-projection computations can be accelerated significantly. We investigated the feasibility of a field-programmable gate array (FPGA) implementation of the separable footprint (SF) forward projector. A 16-bit fixed-point quantization introduces negligible numerical errors without affecting the perceptual image quality. The SF-based 3D cone-beam projector can be efficiently parallelized and its memory bandwidth reduced by exploiting projection geometry and data locality. We demonstrate a fully pipelined, 75-way parallel hardware architecture of the SF forward projector on a Xilinx Virtex-5 FPGA that can complete one forward projection of a 320x320x61 object over 3,625 views in 6.3 seconds.","Title: Image recovery using partitioned-separable paraboloidal surrogate coordinate ascent algorithms.\nYear: 2002\n\nAbstract: Iterative coordinate ascent algorithms have been shown to be useful for image recovery, but are poorly suited to parallel computing due to their sequential nature. This paper presents a new fast converging parallelizable algorithm for image recovery that can be applied to a very broad class of objective functions. This method is based on paraboloidal surrogate functions and a concavity technique. The paraboloidal surrogates simplify the optimization problem. The idea of the concavity technique is to partition pixels into subsets that can be updated in parallel to reduce the computation time. For fast convergence, pixels within each subset are updated sequentially using a coordinate ascent algorithm. The proposed algorithm is guaranteed to monotonically increase the objective function and intrinsically accommodates nonnegativity constraints. A global convergence proof is summarized. Simulation results show that the proposed algorithm requires less elapsed time for convergence than iterative coordinate ascent algorithms. With four parallel processors, the proposed algorithm yields a speedup factor of 3.77 relative to single processor coordinate ascent algorithms for a three-dimensional (3-D) confocal image restoration problem.","Title: Regularized Estimation Of Stokes-Images From Polarimetric Measurements\nYear: 2008\n\nAbstract: In the remote sensing context the goal of imaging polarimetry is to map the state of polarization of a scene of interest. The polarization state of a scene can be represented by the Stokes parameters. Since the Stokes parameters are not directly measurable one must first make several individual measurements and then the infer the Stokes parameters. We approach the Stokes parameter construction problem using penalized-likelihood estimation. Given the measured linearly polarized images, what is the optimal means by which to deblur and denoise and construct the Stokes parameters? In traditional image restoration one attempts to restore the blurred and noise corrupted data directly. In the case of imaging polarimetry we must answer the question of the optimality of restoring the measured data and then forming the Stokes images or restoring the Stokes images directly. An alternative approach is to estimate the Stokes parameters directly. We define our cost function for reconstruction by a weighted least squares data fit penalty and a regularization penalty. We show that for quadratic regularization the estimators of Stokes and intensity images can be made equal by appropriate choice of regularization parameters. It is empirically shown that, when using edge preserving regularization, estimating Stokes parameters directly leads to somewhat lower error.","Title: A new statistical image reconstruction algorithm for polyenergetic X-ray CT\nYear: 2009\n\nAbstract: This paper presents a new statistical reconstruction algorithm for X-ray CT. The algorithm is based on Poisson statistics and a physical model that accounts for the measurement nonlinearities caused by energy-dependent attenuation. We model each voxel's attenuation as a mixture of bone and soft tissue by defining density-dependent tissue fractions, maintaining one unknown per voxel avoiding the need of a pre-segmentation. Rather than requiring the entire X-ray spectrum, the method approximates the 2D beam hardening function corresponding to bone and soft tissue with the 1D function corresponding to water and one or two empirical tuning parameters. Results on simulated human data (NCAT phantom) showed a beam hardening reduction similar to conventional post-processing techniques, but with an improved signal to noise ratio.","Title: Spatial Resolution Properties of Motion-Compensated Tomographic Image Reconstruction Methods.\nYear: 2012\n\nAbstract: Many motion-compensated image reconstruction (MCIR) methods have been proposed to correct for subject motion in medical imaging. MCIR methods incorporate motion models to improve image quality by reducing motion artifacts and noise. This paper analyzes the spatial resolution properties of MCIR methods and shows that nonrigid local motion can lead to nonuniform and anisotropic spatial resolution fo...","Title: Nonrigid Registration Using Regularization that Accommodates Local Tissue Rigidity\nYear: 2006\n\nAbstract: Regularized nonrigid medical image registration algorithms usually estimate the deformation by minimizing a cost function, consisting of a similarity measure and a penalty term that discourages \"unreasonable\" deformations. Conventional regularization methods enforce homogeneous smoothness properties of the deformation field; less work has been done to incorporate tissue-type-specific elasticity information. Yet ignoring the elasticity differences between tissue types can result in non-physical results, such as bone warping. Bone structures should move rigidly (locally), unlike the more elastic deformation of soft issues. Existing solutions for this problem either treat different regions of an image independently, which requires precise segmentation and incurs boundary issues; or use an empirical spatial varying \"filter\" to \"correct\" the deformation field, which requires the knowledge of a stiffness map and departs from the cost-function formulation. We propose a new approach to incorporate tissue rigidity information into the nonrigid registration problem, by developing a space variant regularization function that encourages the local Jacobian of the deformation to be a nearly orthogonal matrix in rigid image regions, while allowing more elastic deformations elsewhere. For the case of X-ray CT data, we use a simple monotonic increasing function of the CT numbers (in HU) as a \"rigidity index\" since bones typically have the highest CT numbers. Unlike segmentation-based methods, this approach is flexible enough to account for partial volume effects. Results using a B-spline deformation parameterization illustrate that the proposed approach improves registration accuracy in inhale-exhale CT scans with minimal computational penalty.","Title: A splitting-based iterative algorithm for accelerated statistical X-ray CT reconstruction.\nYear: 2012\n\nAbstract: Statistical image reconstruction using penalized weighted least-squares (PWLS) criteria can improve image-quality in X-ray computed tomography (CT). However, the huge dynamic range of the statistical weights leads to a highly shift-variant inverse problem making it difficult to precondition and accelerate existing iterative algorithms that attack the statistical model directly. We propose to allev...","Title: A convergence proof of the split Bregman method for regularized least-squares problems.\nYear: 2014\n\nAbstract: The split Bregman (SB) method [T. Goldstein and S. Osher, SIAM J. Imaging Sci., 2 (2009), pp. 323-43] is a fast splitting-based algorithm that solves image reconstruction problems with general l1, e.g., total-variation (TV) and compressed sensing (CS), regularizations by introducing a single variable split to decouple the data-fitting term and the regularization term, yielding simple subproblems that are separable (or partially separable) and easy to minimize. Several convergence proofs have been proposed, and these proofs either impose a \"full column rank\" assumption to the split or assume exact updates in all subproblems. However, these assumptions are impractical in many applications such as the X-ray computed tomography (CT) image reconstructions, where the inner least-squares problem usually cannot be solved efficiently due to the highly shift-variant Hessian. In this paper, we show that when the data-fitting term is quadratic, the SB method is a convergent alternating direction method of multipliers (ADMM), and a straightforward convergence proof with inexact updates is given using [J. Eckstein and D. P. Bertsekas, Mathematical Programming, 55 (1992), pp. 293-318, Theorem 8]. Furthermore, since the SB method is just a special case of an ADMM algorithm, it seems likely that the ADMM algorithm will be faster than the SB method if the augmented Largangian (AL) penalty parameters are selected appropriately. To have a concrete example, we conduct a convergence rate analysis of the ADMM algorithm using two splits for image restoration problems with quadratic data-fitting term and regularization term. According to our analysis, we can show that the two-split ADMM algorithm can be faster than the SB method if the AL penalty parameter of the SB method is suboptimal. Numerical experiments were conducted to verify our analysis.","Title: Covariance Of Kinetic Parameter Estimators Based On Time Activity Curve Reconstructions: Preliminary Study On 1d Dynamic Imaging\nYear: 2004\n\nAbstract: We provide approximate expressions for the covariance matrix of kinetic parameter estimators based on time activity curve (TAC) reconstructions when TACs are modeled as a linear combination of temporal basis functions such as B-splines. The approximations are useful tools for assessing and optimizing the basis functions for TACs and the temporal bins for data in terms of computation and efficiency. In this paper we analyze a 1D temporal problem for simplicity, and we consider a scenario where TACs are reconstructed by penalized-likelihood (PL) estimation incorporating temporal regularization, and kinetic parameters are obtained by maximum likelihood (ML) estimation. We derive approximate formulas for the covariance of the kinetic parameter estimators using 1) the mean and variance approximations for PL estimators in (Fessler, 1996) and 2) Cramer-Rao bounds. The approximations apply to list-mode data as well as bin-mode data.","Title: Hybrid Poisson/polynomial objective functions for tomographic image reconstruction from transmission scans\nYear: 1995\n\nAbstract: This paper describes rapidly converging algorithms for computing attenuation maps from Poisson transmission measurements using penalized-likelihood objective functions. We demonstrate that an under-relaxed cyclic coordinate-ascent algorithm converges faster than the convex algorithm of Lange (see ibid., vol.4, no.10, p.1430-1438, 1995), which in turn converges faster than the expectation-maximization (EM) algorithm for transmission tomography. To further reduce computation, one could replace the log-likelihood objective with a quadratic approximation. However, we show with simulations and analysis that the quadratic objective function leads to biased estimates for low-count measurements. Therefore we introduce hybrid Poisson/polynomial objective functions that use the exact Poisson log-likelihood for detector measurements with low counts, but use computationally efficient quadratic or cubic approximations for the high-count detector measurements. We demonstrate that the hybrid objective functions reduce computation time without increasing estimation bias","Title: Accelerated nonrigid intensity-based image registration using importance sampling.\nYear: 2009\n\nAbstract: Nonrigid image registration methods using intensity-based similarity metrics are becoming increasingly common tools to estimate many types of deformations. Nonrigid warps can be very flexible with a large number of parameters and gradient optimization schemes are widely used to estimate them. However, for large datasets, the computation of the gradient of the similarity metric with respect to thes...","Title: Gradient Based Image Registration Using Importance Sampling\nYear: 2006\n\nAbstract: Analytical gradient based non-rigid image registration methods, using intensity based similarity measures (e.g. mutual information), have proven to be capable of accurately handling many types of deformations. While their versatility is largely in part to their high degrees of freedom, the computation of the gradient of the similarity measure with respect to the many warp parameters becomes very time consuming. Recently, a simple stochastic approximation method using a small random subset of image pixels to approximate this gradient has been shown to be effective. We propose to use importance sampling to improve the accuracy and reduce the variance of this approximation by preferentially selecting pixels near image edges. Initial empirical results show that a combination of stochastic approximation methods and importance sampling greatly improves the rate of convergence of the registration process while preserving accuracy.","Title: Estimating 3-D respiratory motion from orbiting views by tomographic image registration.\nYear: 2007\n\nAbstract: Respiratory motion remains a significant source of errors in treatment planning for the thorax and upper abdomen. Recently, we proposed a method to estimate two-dimensional (2-D) object motion from a sequence of slowly rotating X-ray projection views, which we called deformation from orbiting views (DOVs). In this method, we model the motion as a time varying deformation of a static prior of the anatomy. We then optimize the parameters of the motion model by maximizing the similarity between the modeled and actual projection views. This paper extends the method to full three-dimensional (3-D) motion and cone-beam projection views. We address several practical issues for using a cone-beam computed tomography (CBCT) scanner that is integrated in a radiotherapy system, such as the effects of Compton scatter and the limited gantry rotation for one breathing cycle. We also present simulation and phantom results to illustrate the performance of this method.","Title: Quadratic Regularization Design for 2-D CT.\nYear: 2009\n\nAbstract: Statistical methods for tomographic image reconstruction have improved noise and spatial resolution properties that may improve image quality in X-ray computed tomography (CT). Penalized weighted least squares (PWLS) methods using conventional quadratic regularization lead to nonuniform and anisotropic spatial resolution due to interactions between the weighting, which is necessary for good noise ...","Title: Accelerating ordered subsets image reconstruction for X-ray CT using spatially nonuniform optimization transfer.\nYear: 2013\n\nAbstract: Statistical image reconstruction algorithms in X-ray computed tomography (CT) provide improved image quality for reduced dose levels but require substantial computation time. Iterative algorithms that converge in few iterations and that are amenable to massive parallelization are favorable in multiprocessor implementations. The separable quadratic surrogate (SQS) algorithm is desirable as it is simple and updates all voxels simultaneously. However, the standard SQS algorithm requires many iterations to converge. This paper proposes an extension of the SQS algorithm that leads to spatially nonuniform updates. The nonuniform (NU) SQS encourages larger step sizes for the voxels that are expected to change more between the current and the final image, accelerating convergence, while the derivation of NU-SQS guarantees monotonic descent. Ordered subsets (OS) algorithms can also accelerate SQS, provided suitable \"subset balance\" conditions hold. These conditions can fail in 3-D helical cone-beam CT due to incomplete sampling outside the axial region-of-interest (ROI). This paper proposes a modified OS algorithm that is more stable outside the ROI in helical CT. We use CT scans to demonstrate that the proposed NU-OS-SQS algorithm handles the helical geometry better than the conventional OS methods and \"converges\" in less than half the time of ordinary OS-SQS.","Title: Conjugate phase MRI reconstruction with spatially variant sample density correction.\nYear: 2005\n\nAbstract: A new image reconstruction method to correct for the effects of magnetic field inhomogeneity in non-Cartesian sampled magnetic resonance imaging (MRI) is proposed. The conjugate phase reconstruction method, which corrects for phase accumulation due to applied gradients and magnetic field inhomogeneity, has been commonly used for this case. This can lead to incomplete correction, in part, due to th...","Title: Regularization Design For Isotropic Spatial Resolution In Motion-Compensated Image Reconstruction\nYear: 2011\n\nAbstract: Patient motion degrades image quality in medical imaging. Gating can reduce motion artifacts by using part of the acquired data, but can increase noise. Motion-compensated image reconstruction (MCIR) utilizes all collected data with motion information to reduce motion artifacts and noise.Interactions between Poisson log-likelihood and quadratic regularizers lead to nonuniform and anisotropic spatial resolution in the static case. These undesirable problems can become worse in MCIR due to local motion. We previously compensated for local volume changes in MCIR to provide approximately uniform spatial resolution, but achieved isotropic resolution only for the static case.This paper proposes a quadratic spatial regularizer design that achieves nearly uniform and isotropic spatial resolution in MCIR. We consider \"analytical approach\" to regularization design that was developed for static image reconstruction and extend it to MCIR methods based on a general parametric motion model. Our proposed regularizer can compensate not only for the effects of interactions between the Poisson log-likelihood and the spatial regularizer but also for the effects of nonrigid motion. A 2D PET simulation demonstrates the theoretical results.","Title: Simplified Digital Holographic Reconstruction Using Statistical Methods\nYear: 2004\n\nAbstract: For reconstructing a complex object wavefront from digital holograms. we propose a new penalized-likelihood approach based on the measurement statistics and edge-preserving regularization. The log-likelihood is complicated since the measurements are related to the magnitude of the complex beam. We use optimization transfer to derive a new simplified iterative algorithm that monotonically decreases the cost function. Unlike the conventional FFT-based holographic reconstruction method, the new approach uses all of the measured data, and can be applied to holograms with any (known) reference beam pattern. Simulation results demonstrate the potential for improved image quality.","Title: Noise Properties of Motion-Compensated Tomographic Image Reconstruction Methods\nYear: 2013\n\nAbstract: Motion-compensated image reconstruction (MCIR) methods incorporate motion models to improve image quality in the presence of motion. MCIR methods differ in terms of how they use motion information and they have been well studied separately. However, there have been less theoretical comparisions of different MCIR methods. This paper compares the theoretical noise properties of three popular MCIR methods assuming known nonrigid motion. We show the relationship among three MCIR methods-motion-compensated temporal regularization (MTR), the parametric motion model (PMM), and post-reconstruction motion correction (PMC)-for penalized weighted least square cases. These analyses show that PMM and MTR are matrix-weighted sums of all registered image frames, while PMC is a scalar-weighted sum. We further investigate the noise properties of MCIR methods with Poisson models and quadratic regularizers by deriving accurate and fast variance prediction formulas using an “analytical approach.” These theoretical noise analyses show that the variances of PMM and MTR are lower than or comparable to the variance of PMC due to the statistical weighting. These analyses also facilitate comparisons of the noise properties of different MCIR methods, including the effects of different quadratic regularizers, the influence of the motion through its Jacobian determinant, and the effect of assuming that total activity is preserved. Two-dimensional positron emission tomography simulations demonstrate the theoretical results.","Title: ITERATIVE SORTING FOR 4DCT IMAGES BASED ON INTERNAL ANATOMY MOTION\nYear: 2007\n\nAbstract: Geometric uncertainties caused by respiratory motion complicate radiotherapy treatment planning. Therefore 4D CT imaging is important in characterizing anatomy motion during breathing. Current 4D CT imaging techniques using multislice CT scanners involve multiple scans at several axial positions and retrospective sorting processes. Most sorting methods are based on externally monitored signals recorded by external monitoring instruments, which may not always accurately catch the actual breathing status and may lead to severe discontinuity artifacts in the sorted CT volumes. We propose a method to reconstruct time-resolved CT volumes based on internal motion to avoid the inaccuracies caused by external breathing signals. In our method, we iteratively sort the 4D CT slices using internal motion based breathing indices. In each iteration, respiratory motion is estimated by updating a motion model to best match a deformed reference volume to each moving multi-slice sub-volumes. The breathing indices as well as the reference volumes are refined for each iteration based on the currently estimated respiratory motion. An example is presented to illustrate the feasibility of our 4D CT sorting method without using any external motion monitoring systems.","Title: Spoke pulse design in magnetic resonance imaging using greedy minimax algorithm\nYear: 2013\n\nAbstract: Spoke RF pulse design in MRI requires joint optimization of the k-space trajectory and RF pulse weights. This design task is often modelled as a sparse approximation problem with a cost function evaluating the l2 norm of the excitation error, which can be approximately solved using the orthogonal matching pursuit (OMP) algorithm. However, l2 optimization does not strictly regulate a maximum deviation between excitation and desired patterns, and may leave bright or dark spots in the image. In this paper, we model the pulse design problem as a sparse approximation problem with an l∞ norm cost function, and propose a greedy algorithm for solving this new problem. Simulation results demonstrate that our algorithm can produce improved spoke RF pulses (reduced maximum error) compared to l2 optimization.","Title: Regularized Parallel Mri Reconstruction Using An Alternating Direction Method Of Multipliers\nYear: 2011\n\nAbstract: Using sparsity-based regularization to improve magnetic resonance image (MRI) reconstruction quality demands computation-intensive nonlinear optimization. In this paper, we develop an iterative algorithm based on the method of multipliers-augmented Lagrangian (AL) formalism-for reconstruction from sensitivity encoded data using sparsity-based regularization. We first convert the unconstrained reconstruction problem into an equivalent constrained optimization task and attack the constrained version in an AL framework using an alternating direction minimization method-this leads to an alternating direction method of multipliers whose intermediate steps are amenable to parallelization. Numerical experiments with in-vivo human brain data illustrate that the proposed algorithm converges faster than both general-purpose optimization algorithms such as nonlinear conjugate gradient (NCG) and state-of-the-art MFISTA.","Title: Fast Joint Reconstruction Of Dynamic R-2* And Field Maps In Functional Mri\nYear: 2008\n\nAbstract: Blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) is conventionally done by reconstructing T-2*-weighted images. However, since the images are unitless they are nonquantifiable in terms of important physiological parameters. An alternative approach is to reconstruct R-2* maps which are quantifiable and have comparable BOLD contrast as T-2*-weighted images. However, conventional R-2* mapping involves long readouts and ignores relaxation during readout. Another problem with fMRI imaging is temporal drift/fluctuations in off-resonance. Conventionally, a field map is collected at the start of the fMRI study to correct for off-resonance, ignoring an), temporal changes. Here, we propose a new fast regularized iterative algorithm that Jointly reconstructs R-2* and field maps for all time frames in fMRI data. To accelerate the algorithm we linearize the MR signal model, enabling the use of fast regularized iterative reconstruction methods. The regularizer was designed to account for the different resolution properties of both R-2* and field maps and provide uniform spatial resolution. For fMRI data with the same temporal frame rate as data collected for T-2*-weighted imaging the resulting R-2* maps performed comparably to T-2*-weighted images in activation detection while also correcting for spatially global and local temporal changes in off-resonance.","Title: Augmented Lagrangian With Variable Splitting For Faster Non-Cartesian L-1-Spirit Mr Image Reconstruction\nYear: 2014\n\nAbstract: SPIRiT (iterative self-consistent parallel imaging reconstruction), and its sparsity-regularized variant L-1-SPIRiT, are compatible with both Cartesian and non-Cartesian magnetic resonance imaging sampling trajectories. However, the non-Cartesian framework is more expensive computationally, involving a nonuniform Fourier transform with a nontrivial Gram matrix. We propose a novel implementation of the regularized reconstruction problem using variable splitting, alternating minimization of the augmented Lagrangian, and careful preconditioning. Our new method based on the alternating direction method of multipliers converges much faster than existing methods because of the preconditioners' heightened effectiveness. We demonstrate such rapid convergence substantially improves image quality for a fixed computation time. Our framework is a step forward towards rapid non-Cartesian L-1-SPIRiT reconstructions.","Title: Regularization Designs for Uniform Spatial Resolution and Noise Properties in Statistical Image Reconstruction for 3-D X-ray CT\nYear: 2015\n\nAbstract: Statistical image reconstruction methods for X-ray computed tomography (CT) provide improved spatial resolution and noise properties over conventional filtered back-projection (FBP) reconstruction, along with other potential advantages such as reduced patient dose and artifacts. Conventional regularized image reconstruction leads to spatially variant spatial resolution and noise characteristics because of interactions between the system models and the regularization. Previous regularization design methods aiming to solve such issues mostly rely on circulant approximations of the Fisher information matrix that are very inaccurate for undersampled geometries like short-scan cone-beam CT. This paper extends the regularization method proposed in [1] to 3-D cone-beam CT by introducing a hypothetical scanning geometry that helps address the sampling properties. The proposed regularization designs were compared with the original method in [1] with both phantom simulation and clinical reconstruction in 3-D axial X-ray CT. The proposed regularization methods yield improved spatial resolution or noise uniformity in statistical image reconstruction for short-scan axial cone-beam CT.","Title: Combining ordered subsets and momentum for accelerated X-ray CT image reconstruction.\nYear: 2015\n\nAbstract: Statistical X-ray computed tomography (CT) reconstruction can improve image quality from reduced dose scans, but requires very long computation time. Ordered subsets (OS) methods have been widely used for research in X-ray CT statistical image reconstruction (and are used in clinical PET and SPECT reconstruction). In particular, OS methods based on separable quadratic surrogates (OS-SQS) are massively parallelizable and are well suited to modern computing architectures, but the number of iterations required for convergence should be reduced for better practical use. This paper introduces OS-SQS-momentum algorithms that combine Nesterov's momentum techniques with OS-SQS methods, greatly improving convergence speed in early iterations. If the number of subsets is too large, the OS-SQS-momentum methods can be unstable, so we propose diminishing step sizes that stabilize the method while preserving the very fast convergence behavior. Experiments with simulated and real 3D CT scan data illustrate the performance of the proposed algorithms.","Title: Fast X-ray CT image reconstruction using a linearized augmented lagrangian method with ordered subsets.\nYear: 2015\n\nAbstract: Augmented Lagrangian (AL) methods for solving convex optimization problems with linear constraints are attractive for imaging applications with composite cost functions due to the empirical fast convergence rate under weak conditions. However, for problems such as X-ray computed tomography (CT) image reconstruction, where the inner least-squares problem is challenging and requires iterations, AL methods can be slow. This paper focuses on solving regularized (weighted) least-squares problems using a linearized variant of AL methods that replaces the quadratic AL penalty term in the scaled augmented Lagrangian with its separable quadratic surrogate function, leading to a simpler ordered-subsets (OS) accelerable splitting-based algorithm, OS-LALM. To further accelerate the proposed algorithm, we use a second-order recursive system analysis to design a deterministic downward continuation approach that avoids tedious parameter tuning and provides fast convergence. Experimental results show that the proposed algorithm significantly accelerates the convergence of X-ray CT image reconstruction with negligible overhead and can reduce OS artifacts when using many subsets.","Title: Fast parallel MR image reconstruction via B1-based, adaptive restart, iterative soft thresholding algorithms (BARISTA).\nYear: 2015\n\nAbstract: Sparsity-promoting regularization is useful for combining compressed sensing assumptions with parallel MRI for reducing scan time while preserving image quality. Variable splitting algorithms are the current state-of-the-art algorithms for SENSE-type MR image reconstruction with sparsity-promoting regularization. These methods are very general and have been observed to work with almost any regularizer; however, the tuning of associated convergence parameters is a commonly-cited hindrance in their adoption. Conversely, majorize-minimize algorithms based on a single Lipschitz constant have been observed to be slow in shift-variant applications such as SENSE-type MR image reconstruction since the associated Lipschitz constants are loose bounds for the shift-variant behavior. This paper bridges the gap between the Lipschitz constant and the shift-variant aspects of SENSE-type MR imaging by introducing majorizing matrices in the range of the regularizer matrix. The proposed majorize-minimize methods (called BARISTA) converge faster than state-of-the-art variable splitting algorithms when combined with momentum acceleration and adaptive momentum restarting. Furthermore, the tuning parameters associated with the proposed methods are unitless convergence tolerances that are easier to choose than the constraint penalty parameters required by variable splitting algorithms.","Title: Edge-preserving image denoising via group coordinate descent on the GPU.\nYear: 2015\n\nAbstract: Image denoising is a fundamental operation in image processing, and its applications range from the direct (photographic enhancement) to the technical (as a subproblem in image reconstruction algorithms). In many applications, the number of pixels has continued to grow, while the serial execution speed of computational hardware has begun to stall. New image processing algorithms must exploit the power offered by massively parallel architectures like graphics processing units (GPUs). This paper describes a family of image denoising algorithms well-suited to the GPU. The algorithms iteratively perform a set of independent, parallel 1D pixel-update subproblems. To match GPU memory limitations, they perform these pixel updates in-place and only store the noisy data, denoised image, and problem parameters. The algorithms can handle a wide range of edge-preserving roughness penalties, including differentiable convex penalties and anisotropic total variation. Both algorithms use the majorize-minimize framework to solve the 1D pixel update subproblem. Results from a large 2D image denoising problem and a 3D medical imaging denoising problem demonstrate that the proposed algorithms converge rapidly in terms of both iteration and run-time.","Title: Multi-material decomposition using statistical image reconstruction for spectral CT.\nYear: 2014\n\nAbstract: Spectral computed tomography (CT) provides information on material characterization and quantification because of its ability to separate different basis materials. Dual-energy (DE) CT provides two sets of measurements at two different source energies. In principle, two materials can be accurately decomposed from DECT measurements. However, many clinical and industrial applications require three or more material images. For triple-material decomposition, a third constraint, such as volume conservation, mass conservation or both, is required to solve three sets of unknowns from two sets of measurements. The recently proposed flexible image-domain (ID) multi-material decomposition) method assumes each pixel contains at most three materials out of several possible materials and decomposes a mixture pixel by pixel. We propose a penalized-likelihood (PL) method with edge-preserving regularizers for each material to reconstruct multi-material images using a similar constraint from sinogram data. We develop an optimization transfer method with a series of pixel-wise separable quadratic surrogate (PWSQS) functions to monotonically decrease the complicated PL cost function. The PWSQS algorithm separates pixels to allow simultaneous update of all pixels, but keeps the basis materials coupled to allow faster convergence rate than our previous proposed material- and pixel-wise SQS algorithms. Comparing with the ID method using 2-D fan-beam simulations, the PL method greatly reduced noise, streak and cross-talk artifacts in the reconstructed basis component images, and achieved much smaller root mean square errors.","Title: Alternating Direction Method of Multiplier for Tomography With Nonlocal Regularizers.\nYear: 2014\n\nAbstract: The ordered subset expectation maximization (OSEM) algorithm approximates the gradient of a likelihood function using a subset of projections instead of using all projections so that fast image reconstruction is possible for emission and transmission tomography such as SPECT, PET, and CT. However, OSEM does not significantly accelerate reconstruction with computationally expensive regularizers such as patch-based nonlocal (NL) regularizers, because the regularizer gradient is evaluated for every subset. We propose to use variable splitting to separate the likelihood term and the regularizer term for penalized emission tomographic image reconstruction problem and to optimize it using the alternating direction method of multiplier (ADMM). We also propose a fast algorithm to optimize the ADMM parameter based on convergence rate analysis. This new scheme enables more sub-iterations related to the likelihood term. We evaluated our ADMM for 3-D SPECT image reconstruction with a patch-based NL regularizer that uses the Fair potential function. Our proposed ADMM improved the speed of convergence substantially compared to other existing methods such as gradient descent, EM, and OSEM using De Pierro's approach, and the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm.","Title: Regularized Estimation Of Magnitude And Phase Of Multi-Coil B-1 Field Via Bloch-Siegert B-1 Mapping And Coil Combination Optimizations\nYear: 2014\n\nAbstract: Parallel excitation requires fast and accurate map estimation. Bloch-Siegert (BS) B-1 mapping is very fast and accurate over a large dynamic range. When applied to multi-coil systems, however, this phase-based method may produce low signal-to-noise ratio estimates in low magnitude regions due to localized excitation patterns of parallel excitation systems. Also, the imaging time increases with the number of coils. In this work, we first propose to modify the standard BS B-1 mapping sequence so that it avoids the scans required by previous B-1 phase estimation methods. A regularized method is then proposed to jointly estimate the magnitude and phase of multi-coil B-1 maps from BS mapping data, improving estimation quality by using the prior knowledge of the smoothness of B-1 magnitude and phase. Lastly, we use Cramer-Rao lower bound analysis to optimize the coil combinations, to improve the quality of the raw data for B-1 estimation. The proposed methods are demonstrated by simulations and phantom experiments.","Title: Nmr Object Boundaries - B-Spline Modeling And Estimator Performance\nYear: 1995\n\nAbstract: We give estimation error bounds and specify optimal estimators for continuous, closed boundary curves in an NMR image. The boundary is parameterized us- ing periodic B-Splines. A Cramer-Rao lower bound on mean-square-estimate error in the presence of system smoothing and Gaussian noise is derived, and the per- formance of maximum likelihood and penalized maxi- muin likelihood estimators is compared to this bound. Finally, we comment on the usefulness of estimates of the boundary for providing anatomical side information in the reconstruction of functional tomographic images like those of a PET or SPECT system.","Title: Regularized estimation of Bloch-Siegert |B1+| maps in MRI\nYear: 2014\n\nAbstract: The Bloch-Siegert (BS) method is a fast method for finding RF transmit fields (|B1+| maps) in MRI based on the phase shift induced by an off-resonance pulse. The phase calculation can be very noisy in regions with low image magnitude, leading to inaccurate estimations using the conventional method. This paper proposes a penalized likelihood (PL) estimator of the |B1+| map in the image domain, and a fast optimization transfer algorithm for solving the problem. We validated our proposed method with both simulation and experimental data sets.","Title: Phase Retrieval Of Sparse Signals Using Optimization Transfer And Admm\nYear: 2014\n\nAbstract: We propose a reconstruction method for the phase retrieval problem prevalent in optics, crystallography, and other imaging applications. Our approach uses signal sparsity to provide robust reconstruction, even in the presence of outliers. Our method is multi-layered, involving multiple random initial conditions, convex majorization, variable splitting, and alternating directions method of multipliers (ADMM)-based implementation. Monte Carlo simulations demonstrate that our algorithm can correctly and robustly detect sparse signals from full and undersampled sets of squared-magnitude-only measurements, corrupted by additive noise or outliers.","Title: Alternating minimization approach for multi-frame image reconstruction.\nYear: 2012\n\nAbstract: There are a variety of imaging modalities that record a sequence of measurements where the sensor and/or the objects in the scene aremoving and the goal is to reconstruct an image without motion blur. Examples include multi-frame super-resolution problems and motion-compensated image reconstruction problems in medical imaging. Various methods have been proposed for such applications, often in the context of specific imaging modalities. However, many such methods can be formulated in a common framework and thus solved by the same optimization method. To solve the reconstruction problem efficiently, the optimization method must be designed carefully.This paper proposes a novel approach to solve multi-frame image reconstruction problems more efficiently. We use a variable-splitting technique to dissociate the original problem into a few simpler problems that are then solved individually using an alternating minimization method. The proposed method is amenable to preconditioning, parallelization, and application of block iterative algorithms to the sub-problems. Simulation results demonstrate that even with simple diagonal or circulant preconditioners, the proposed method converges faster than the conjugate gradient (CG) method.","Title: A Bayesian approach to reconstruction from incomplete projections of a multiple object 3D domain\nYear: 1989\n\nAbstract: An estimation approach is described for three-dimensional reconstruction from line integral projections using incomplete and very noisy data. Generalized cylinders parameterized by stochastic dynamic models are used to represent prior knowledge about the properties of objects of interest in the probed domain. The object models, a statistical measurement model, and the maximum a posteriori probability performance criterion are combined to reformulate the reconstruction problem as a computationally challenging nonlinear estimation problem. For computational feasibility, a suboptimal hierarchical algorithm is described whose individual steps are locally optimal and are combined to satisfy a global optimality criterion. The formulation and algorithm are restricted to objects whose center axis is a single-valued function of a fixed spatial coordinate. Simulation examples demonstrate accurate reconstructions with as few as four views in a 135 degrees sector, at an average signal-to-noise ratio of 3.3.","Title: Penalized weighted least-squares image reconstruction for positron emission tomography.\nYear: 1994\n\nAbstract: This paper presents an image reconstruction method for positron-emission tomography (PET) based on a penalized, weighted least- squares (PWLS) objective. For PET measurements that are precorrected for accidental coincidences, we argue statistically that a least-squares ob- jective function is as appropriate, if not more so, than the popular Pois- son likelihood objective. We propose a simple data-based method for determining the weights that accounts for attenuation and detector effi- ciency. A nonnegative successive over-relaxation (+SOR) algorithm con- verges rapidly to the global minimum of the PWLS objective. Quan- titative simulation results demonstrate that the bias/var iance tradeoff of the PWLS+SOR method is comparable to the maximum-likelihood expectation-maximization (ML-EM) method (but with fewer iterations), and is improved relative to the conventional filtered backpr ojection (FBP) method. Qualitative results suggest that the streak artifa cts common to the FBP method are nearly eliminated by the PWLS+SOR method, and indicate that the proposed method for weighting the measurements is a sig- nificant factor in the improvement over FBP.","Title: Fast, iterative, field-corrected image reconstruction for MRI\nYear: 2002\n\nAbstract: Magnetic field inhomogeneities cause distortions in the reconstructed images for non-cartesian k-space MRI (using spirals, for example). Several noniterative methods are currently used to compensate for the off-resonance during the reconstruction, but these methods rely on the assumption of a smoothly varying field map. Recently, iterative methods have been proposed that do not rely on this assumption and have the potential to estimate undistorted field maps, but suffer from prohibitively long computation times. In this abstract we present a min-max derived, time-segmented approximation to the signal equation for MRI that, when combined with the nonuniform fast Fourier transform, provides a fast, accurate field-corrected image reconstruction.","Title: Segmentation-free statistical image reconstruction for polyenergetic X-ray computed tomography\nYear: 2002\n\nAbstract: This paper describes a statistical iterative reconstruction method for X-ray CT based on a physical model that accounts for the polyenergetic X-ray source spectrum and the measure- ment nonlinearities caused by energy-dependent attenuation. The algorithm accommodates mixtures of tissues with known mass attenuation coefficients but unknown densities. We formulate a penalized-likelihood approach for this polyen- ergetic model based on Poisson statistics.","Title: Moments of implicitly defined estimators (e.g. ML and MAP): applications to transmission tomography\nYear: 1995\n\nAbstract: Many estimators in signal processing problems are defined implicitly as the maximum of an objective function, such as maximum likelihood (ML) and maximum a posteriori (MAP) methods. Exact analytical expressions for the mean and variance of such estimators are usually unavailable, so investigators usually resort to numerical simulations. The paper describes approximate analytical expressions for the mean and variance of implicitly defined estimators. The expressions are defined solely in terms of the partial derivatives of whatever objective function one uses for estimation. The authors demonstrate the utility and accuracy of the approximations in a PET transmission computed tomography application with Poisson statistics. The approximations should be useful in a wide range of estimation problems","Title: Compensation for nonuniform resolution using penalized-likelihood reconstruction in space-variant imaging systems.\nYear: 2004\n\nAbstract: Imaging systems that form estimates using a statistical approach generally yield images with nonuniform resolution properties. That is, the reconstructed images possess resolution properties marked by space-variant and/or anisotropic responses. We have previously developed a space-variant penalty for penalized-likelihood (PL) reconstruction that yields nearly uniform resolution properties. We demonstrated how to calculate this penalty efficiently and apply it to an idealized positron emission tomography (PET) system whose geometric response is space-invariant. In this paper, we demonstrate the efficient calculation and application of this penalty to space-variant systems. (The method is most appropriate when the system matrix has been precalculated.) We apply the penalty to a large field of view PET system where crystal penetration effects make the geometric response space-variant, and to a two-dimensional single photon emission computed tomography system whose detector responses are modeled by a depth-dependent Gaussian with linearly varying full-width at half-maximum. We perform a simulation study comparing reconstructions using our proposed PL approach with other reconstruction methods and demonstrate the relative resolution uniformity, and discuss tradeoffs among estimators that yield nearly uniform resolution. We observe similar noise performance for the PL and post-smoothed maximum-likelihood (ML) approaches with carefully matched resolution, so choosing one estimator over another should be made on other factors like computational complexity and convergence rates of the iterative reconstruction. Additionally, because the postsmoothed ML and the proposed PL approach can outperform one another in terms of resolution uniformity depending on the desired reconstruction resolution, we present and discuss a hybrid approach adopting both a penalty and post-smoothing.","Title: Penalized likelihood emission image reconstruction with uncertain boundary information\nYear: 1997\n\nAbstract: In this paper, a method is introduced for incorporating perfectly registered MRI boundary information into a penalized likelihood emission reconstruction scheme. The boundary curve is modeled as a periodic spline whose coefficients are estimated from the MRI image. The resulting boundary estimate is mapped to a spatially variant set of Gibbs weights. When incorporated into a quadratic roughness penalty, these weights improve emission reconstruction bias/variance performance by preventing smoothing across the estimated boundary. Finally, we derive a new penalty function that accounts for the uncertainty inherent in the boundary estimates","Title: Iterative image reconstruction in MRI with separate magnitude and phase regularization\nYear: 2004\n\nAbstract: Iterative methods for image reconstruction in MRI are useful in several applications, including reconstruction from non-Cartesian k-space samples, compensation for magnetic field inhomogeneities, and imaging with multiple receive coils. Existing iterative MR image reconstruction methods are either unregularized, and therefore sensitive to noise, or have used regularization methods that smooth the complex valued image. These existing methods regularize the real and imaginary components of the image equally. In many MRI applications, including T ∗ 2-weighted imaging as used in fMRI BOLD imaging, one expects most of the signal in- formation of interest to be contained in the magnitude of the voxel value, whereas the phase values are expected to vary smoothly spatially. This paper proposes separate regu- larization of the magnitude and phase components, preserv- ing the spatial resolution of the magnitude component while strongly regularizing the phase component. This leads to a non-convex regularized least-squares cost function. We describe a new iterative algorithm that monotonically de- creases this cost function. The resulting images have re- duced noise relative to conventional regularization methods.","Title: Edge-preserving tomographic reconstruction with nonlocal regularization.\nYear: 2002\n\nAbstract: Tomographic image reconstruction using statistical methods can provide more accurate system modeling, statistical models, and physical constraints than the conventional filtered backprojection (FBP) method. Because of the ill posedness of the reconstruction problem, a roughness penalty is often imposed on the solution to control noise. To avoid smoothing of edges, which are important image attributes, various edge-preserving regularization methods have been proposed. Most of these schemes rely on information from local neighborhoods to determine the presence of edges. In this paper, we propose a cost function that incorporates nonlocal boundary information into the regularization method. We use an alternating minimization algorithm with deterministic annealing to minimize the proposed cost function, jointly estimating region boundaries and object pixel values. We apply variational techniques implemented using level-sets methods to update the boundary estimates; then, using the most recent boundary estimate, we minimize a space-variant quadratic cost function to update the image estimate. For the positron emission tomography transmission reconstruction application, we compare the bias-variance tradeoff of this method with that of a \"conventional\" penalized-likelihood algorithm with local Huber roughness penalty.","Title: Analysis of observer performance in known-location tasks for tomographic image reconstruction\nYear: 2006\n\nAbstract: We consider the task of detecting a statistically varying signal of known location on a statistically varying background in a reconstructed tomographic image. We analyze the performance of linear observer models in this task. We show that, if one chooses a suitable reconstruction method, a broad family of linear observers can exactly achieve the optimal detection performance attainable with any combination of a linear observer and linear reconstructor. This conclusion encompasses several well-known observer models from the literature, including models with a frequency-selective channel mechanism and certain types of internal noise. Interestingly, the \"optimal\" reconstruction methods are unregularized and in some cases quite unconventional. These results suggest that, for the purposes of designing regularized reconstruction methods that optimize lesion detectability, known-location tasks are of limited use.","Title: Regularized fieldmap estimation in MRI\nYear: 2006\n\nAbstract: In fast MR imaging with long readout times, such as echo- planar imaging (EPI) and spiral scans, it is important to cor- rect for the effects of field inhomogeneity to reduce image distortion and blurring. Such corrections require an accurate field map, a map of the off-resonance frequency at each voxel. Standard fieldmap estimation methods yield noisy fieldmaps, particularly in image regions having low spin density. This paper describes regularized methods for fieldmap estimation. These methods exploit the factthatfieldmaps are smooth func- tions. Efficient convergent algorithms are given even though the problem is highly nonlinear. Results show that the pro- posed regularized methods significantly improve the quality of fieldmap estimates relative to conventional unregularized methods.","Title: Spatial resolution analysis of iterative image reconstruction with separate regularization of real and imaginary parts\nYear: 2006\n\nAbstract: A common method of improving the conditioning in itera- tive image reconstruction is to include regularization in the re- construction algorithm. One such regularization is the rough- ness penalty, which when used in the algorithm encourages smoother images. For complex valued images, the rough- ness penalty typically penalizes equally the real and imagi- nary parts. The desired resolution of the reconstructed image can then be evaluated using the local impulse response. A fast algorithm to calculate it was developed for the typical rough- ness penalty, used for matching the regularization parameter expediently to the desired resolution. For some cases its ad- vantageous to penalize independently the real and imaginary parts. This paper proposes a fast algorithm to calculate the local impulse response for that penalty and applies it to an fMRI reconstruction problem.","Title: Regularization for uniform spatial resolution properties in penalized-likelihood image reconstruction.\nYear: 2000\n\nAbstract: Traditional space-invariant regularization methods in tomo- graphic image reconstruction using penalized-likelihood estimators pro- duce images with nonuniformspatial resolution properties. The local point spread functions that quantify the local smoothing properties of such es- timators are not only space-variant and asymmetric, but are also object- dependent even for space-invariant imaging systems. We propose a new quadratic regularization scheme for shift-invariant imaging systems that yields increased spatial uniformity motivated by the least-squares fitting of a parameterized local impulse response to a desired global response. We demonstrate the increased spatial uniformity of this new method versus conventional quadratic regularization schemes through an investigation of local point spread functions, and through reconstruction of thorax phan- tom data with known structure.","Title: Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT\nYear: 2006\n\nAbstract: In order to reconstruct attenuation maps with improved spatial resolution and quantitative accuracy, we developed an approximate method of incorporating system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission reconstruction. Our method approximately models the blur caused by the finite intrinsic detector resolution, the nonideal source collimation and detector collimation. We derived the formulation using the optimization transfer principle as in the derivation of the OSTR algorithm. The formulation includes one forward-blur step and one back-blur step, which do not severely slow down reconstruction. The formulation could be applicable to various transmission geometries, such as point-source, line-source, and sheet-source systems. Through computer simulations of the MCAT phantom and transmission measurements of the air-filled Data Spectrum Deluxe single photo emission computed tomography (SPECT) Phantom on a system which employed a cone-beam geometry and a system which employed a scanning-line-source geometry, we showed that incorporation of RC increased spatial resolution and improved the quantitative accuracy of reconstruction. In simulation studies, attenuation maps reconstructed with RC correction improved the quantitative accuracy of emission reconstruction.","Title: REGULARIZED B1+ MAP ESTIMATION IN MRI\nYear: 2007\n\nAbstract: A challenge in MR imaging is that RF transmit coils produce non-uniform field strengths, so an excitation pulse will produce tip angles that vary substantially from the desired tip angle over the field of view. For parallel transmit excitation (using a coil array), it is important to have a map of the B1+ field strength (and phase) for RF pulse design. Standard B1+ map estimation methods perform poorly in image regions with low spin density. This paper describes a regularized method for B1+ map estimation using MR scans for each coil and for two or more tip angles. Using these scans and exploiting the fact that maps are generally smooth, the iterative algorithm estimates both the magnitude and phase at each coil's B1+ map. Results from both simulations and real MR data show significant improvements over conventional unregularized methods for B1 + mapping.","Title: MODEL-BASED MR IMAGE RECONSTRUCTION WITH COMPENSATION FOR THROUGH-PLANE FIELD INHOMOGENEITY\nYear: 2007\n\nAbstract: To improve image quality in susceptibility-weighted MR imaging, it is important to correct for the effects of field inhomogeneity. In particular, susceptibility differences between air and tissue induce magnetic field nonuniformity; often those susceptibility effects have nonzero through-plane gradients that lead to spin dephasing across the slice within each voxel. If uncorrected, these through-plane gradients cause signal loss in the reconstructed images. Several methods exist for reconstructing MR images with compensation for field inhomogeneity, but most of these methods, even the model-based iterative ones, treat the inhomogeneity within each voxel as being a constant, thus ignoring the through-plane gradient effects. This paper describes a model-based iterative method for reconstructing MR images with compensation for field inhomogeneity that accounts for the slice profile and the through-plane gradients of the field inhomogeneity (assumed to be determined by a pre-scan). In particular, this paper describes an accelerated algorithm for implementing the forward model and its adjoint as needed in a conjugate gradient algorithm for iterative MR image reconstruction.","Title: An expanded theoretical treatment of iteration-dependent majorize-minimize algorithms.\nYear: 2007\n\nAbstract: The majorize-minimize (MM) optimization technique has received considerable attention in signal and image processing applications, as well as in statistics literature. At each iteration of an MM algorithm, one constructs a tangent majorant function that majorizes the given cost function and is equal to it at the current iterate. The next iterate is obtained by minimizing this tangent majorant function, resulting in a sequence of iterates that reduces the cost function monotonically. A well-known special case of MM methods are expectation-maximization algorithms. In this paper, we expand on previous analyses of MM, due to Fessler and Hero, that allowed the tangent majorants to be constructed in iteration-dependent ways. Also, this paper overcomes an error in one of those earlier analyses. There are three main aspects in which our analysis builds upon previous work. First, our treatment relaxes many assumptions related to the structure of the cost function, feasible set, and tangent majorants. For example, the cost function can be nonconvex and the feasible set for the problem can be any convex set. Second, we propose convergence conditions, based on upper curvature bounds, that can be easier to verify than more standard continuity conditions. Furthermore, these conditions allow for considerable design freedom in the iteration-dependent behavior of the algorithm. Finally, we give an original characterization of the local region of convergence of MM algorithms based on connected (e.g., convex) tangent majorants. For such algorithms, cost function minimizers will locally attract the iterates over larger neighborhoods than typically is guaranteed with other methods. This expanded treatment widens the scope of the MM algorithm designs that can be considered for signal and image processing applications, allows us to verify the convergent behavior of previously published algorithms, and gives a fuller understanding overall of how these algorithms behave.","Title: Discriminative sliding preserving regularization in medical image registration\nYear: 2009\n\nAbstract: Sliding effects often occur along tissue/organ boundaries. For instance, it is widely observed that the lung and diaphragm slide against the rib cage and the atria during breathing. Conventional homogeneous smooth registration methods fail to address this issue. Some recent studies preserve motion discontinuities by either using joint registration/segmentation or utilizing robust regularization energy on the motion field. However, allowing all types of discontinuities is not strict enough for physical deformations. In particular, flows that generate local vacuums or mass collisions should be discouraged by the energy functional. In this study, we propose a regularization energy that encodes a discriminative treatment of different types of motion discontinuities. The key idea is motivated by the Helmholtz-Hodge decomposition, and regards the underlying motion flow as a superposition of a solenoidal component, an irrotational component and a harmonic part. The proposed method applies a homogeneous penalty on the divergence, discouraging local volume change caused by the irrotational component, thus avoiding local vacuum or collision; it regularizes the curl field with a robust functional so that the resulting solenoidal component vanishes almost everywhere except on a singular set where the large shear values are preserved. This singularity set corresponds to sliding interfaces. Preliminary tests with both simulated and clinical data showed promising results.","Title: Regularized MR coil sensitivity estimation using augmented Lagrangian methods\nYear: 2012\n\nAbstract: Several magnetic resonance (MR) parallel imaging techniques require explicit estimates of the receive coil sensitivity profiles. These estimates must be accurate over both the object and its surrounding regions to avoid generating artifacts in the reconstructed images. Statistical estimation methods provide robust sensitivity estimates but can be computationally expensive. In this paper, we propose an augmented Lagrangian (AL) based method that estimates the coil sensitivity by minimizing a quadratic cost function. This method reformulates the finite differencing matrix to allow for exact alternating minimization steps. We also explore a variation of our algorithm that involves intermediate updating of the Lagrange multipliers. We demonstrate that our proposed algorithm converges in half the time of the traditional conjugate gradient method with a circulant preconditioner (PCG) on a real data set.","Title: An accelerated iterative reweighted least squares algorithm for compressed sensing MRI\nYear: 2010\n\nAbstract: Compressed sensing for MRI (CS-MRI) attempts to recover an object from undersampled k-space data by minimizing sparsity-promoting regularization criteria. The iterative reweighted least squares (IRLS) algorithm can perform the minimization task by solving iteration-dependent linear systems, recursively. However, this process can be slow as the associated linear system is often poorly conditioned for ill-posed problems. We propose a new scheme based on the matrix inversion lemma (MIL) to accelerate the solving process. We demonstrate numerically for CS-MRI that our method provides significant speed-up compared to linear and nonlinear conjugate gradient algorithms, thus making it a promising alternative for such applications.","Title: Joint estimation of image and fieldmap in parallel MRI using single-shot acquisitions\nYear: 2010\n\nAbstract: We propose a method for joint reconstruction of dynamic images and fieldmaps in parallel MRI, using single-shot trajectories. We exploit the sensitivity encoding from parallel imaging to reduce the length of acquisition and essentially perform joint reconstruction using just one full k-space dataset. We also explore the use of modified trajectories (both EPI and spiral) that provide full coverage of k-space and also contain enough inherent time differences to permit accurate fieldmap estimation. Finally we improve the efficiency of the reconstruction algorithm by using a linearization technique for fieldmap estimation, which allows the use of the conjugate gradient algorithm.","Title: MODEL-BASED IMAGE RECONSTRUCTION FOR MRI.\nYear: 2010\n\nAbstract: Magnetic resonance imaging (MRI) is a sophisticated and versatile medical imaging modality. Traditionally, MR images are reconstructed from the raw measurements by a simple inverse 2D or 3D fast Fourier transform (FFT). However, there are a growing number of MRI applications where a simple inverse FFT is inadequate, e.g., due to non-Cartesian sampling patterns, non-Fourier physical effects, nonlinear magnetic fields, or deliberate under-sampling to reduce scan times. Such considerations have led to increasing interest in methods for model-based image reconstruction in MRI.","Title: Improved Robust PCA using low-rank denoising with optimal singular value shrinkage\nYear: 2014\n\nAbstract: We study the robust PCA problem of reliably recovering a low-rank signal matrix from a signal-plus-noise-plus-outliers matrix. We analytically characterize the extent to which the singular vectors of the signal-plus-noise-plus-outliers matrix can be degraded by outliers and discuss why a recently proposed method for robust PCA that exploits outlier sparsity to improve low-rank estimation will produce suboptimal low-rank matrix estimates in the presence of noise. Next, we propose a new iterative algorithm for robust PCA that utilizes an optimal, data-driven low-rank matrix estimator (OptShrink). Finally, we show that the proposed approach yields superior background subtraction on a computer vision dataset.","Title: Fast MR image reconstruction with orthogonal wavelet regularization via shift-variant shrinkage\nYear: 2014\n\nAbstract: Algorithms with Lipschitz bounds such as ISTA and FISTA are useful for solving optimization problems with sparsity-promoting regularizers. However, they can be slow in applications that involve shift-variant system matrices. One example of such an application is MRI with multiple sensitivity coils. We propose a reconstruction algorithm for wavelet regularized SENSE MR image reconstruction that exploits the spatial localization of the wavelet basis and the shift-variant behavior of the MR system matrix to accelerate algorithm convergence. Our results indicate that the proposed method is faster than state-of-the-art variable splitting algorithms in terms of convergence speed for a SENSE-type reconstruction problem even when the variable splitting methods are tuned carefully. Unlike variable splitting methods, the proposed method requires no convergence parameter tuning.","Title: Model-based estimation of T2 maps with dual-echo steady-state MR imaging\nYear: 2014\n\nAbstract: Fast and accurate quantification of spin-spin relaxation parameter T2 is of importance for clinical MRI applications. Classical spin echo (SE) sequences yield straightforward T2 estimates, but require undesirably long scans. By contrast, steady-state sequences such as the Dual-Echo Steady-State (DESS) sequence are considerably faster, but produce signals that depend on more complex functions of both desired and nuisance parameters. Conventional method-of-moments estimators exhibit systematic error because of the approximations used to bypass nuisance parameter estimation. To improve T2 mapping accuracy, we propose a novel, model-based approach to this nonlinear estimation problem. We use a fast scan to estimate nuisance parameters M0* and T1, and then use the exact DESS signal model for regularized T2 estimation from DESS data, with minimal approximations. MR brain simulation results show that the proposed approach substantially improves T2 estimation accuracy and precision, compared to conventional method-of-moments estimators.","Title: Benefits of Position-Sensitive Detectors for Radioactive Source Detection\nYear: 2010\n\nAbstract: There are many systems for counting photons such as gamma-rays emitted from radioactive sources. Many of these systems are also position-sensitive, which means that the system provides directional information about recorded events. This paper investigates whether or not the additional information provided by position-sensitive capability improves the performance of detecting a point-source in background. We analyze the asymptotic performance of the generalized likelihood ratio test (GLRT) and a test based on the maximum-likelihood (ML) estimate of the source intensity for systems with and without position-sensitive capability. When the background intensity is known and detector sensitivity is spatially uniform, we prove that position-sensitive capability increases the area under the receiver operating characteristic curve (AUC). For cases when detector sensitivity is nonuniform or background intensity is unknown, we provide numerical results to illustrate the effect of the parameters on detection performance.","Title: Image restoration using non-circulant shift-invariant system models\nYear: 2012\n\nAbstract: Image restoration is a well studied problem and there are several proposed methods for deblurring and denoising. Recently, there is increasing interest in iterative schemes that employ non-quadratic regularizers, especially edge-preserving like Total Variation (TV) and sparsity promoting like l1 regularization. Most methods make simplifying assumptions concerning the system model and the most common one is the use of a circulant blurring model because it facilitates using the FFT. In this work we focus on a more realistic non-circulant blurring model and apply existing algorithms for image restoration with non-quadratic regularization, tailored to work with our non-circulant model.","Title: Optimization transfer approach to joint registration / reconstruction for motion-compensated image reconstruction\nYear: 2010\n\nAbstract: Motion artifacts in image reconstruction problems can be reduced by performing image motion estimation and image reconstruction jointly using a penalized-likelihood cost function. However, updating the motion parameters by conventional gradient-based iterations can be computationally demanding due to the system model required in inverse problems. This paper describes an optimization transfer approach that leads to minimization steps for the motion parameters that have comparable complexity to those needed in image registration problems. This approach can simplify the implementation of motion-compensated image reconstruction (MCIR) methods when the motion parameters are estimated jointly with the reconstructed image.","Title: Cramér Rao bound analysis of joint B1/T1 mapping methods in MRI\nYear: 2010\n\nAbstract: In MRI, RF field inhomogeneity (B1) and relaxation effects (T1) significantly affect both B1 and T1 mapping. Simultaneous joint estimation of both B1 and T1 has the potential to greatly improve both B1 and T1 estimation. This paper analyzes the Cramér Rao Bound for joint B1, T1 estimation using common B1 and T1 pulse sequences. This analysis aids choosing pulse sequences and parameters given desired levels of B1 and T1 accuracy and the inherent trade off between the two mappings.","Title: Non-Cartesian MRI Reconstruction With Automatic Regularization Via Monte-Carlo SURE\nYear: 2013\n\nAbstract: Magnetic resonance image (MRI) reconstruction from undersampled k-space data requires regularization to reduce noise and aliasing artifacts. Proper application of regularization however requires appropriate selection of associated regularization parameters. In this work, we develop a data-driven regularization parameter adjustment scheme that minimizes an estimate [based on the principle of Stein's unbiased risk estimate (SURE)] of a suitable weighted squared-error measure in k-space. To compute this SURE-type estimate, we propose a Monte-Carlo scheme that extends our previous approach to inverse problems (e.g., MRI reconstruction) involving complex-valued images. Our approach depends only on the output of a given reconstruction algorithm and does not require knowledge of its internal workings, so it is capable of tackling a wide variety of reconstruction algorithms and nonquadratic regularizers including total variation and those based on the l1-norm. Experiments with simulated and real MR data indicate that the proposed approach is capable of providing near mean squared-error optimal regularization parameters for single-coil undersampled non-Cartesian MRI reconstruction.","Title: Sure-based parameter selection for parallel MRI reconstruction using GRAPPA and sparsity\nYear: 2013\n\nAbstract: New methods have been developed for parallel MRI reconstruction combining GRAPPA and sparsity. One impediment to the practical application of such methods is selecting a regularization parameter that acceptably balances the contributions of GRAPPA and sparsity. We propose a broadly applicable Monte-Carlo-based approximation to Stein's unbiased risk estimate (SURE) for a suitable weighted mean-squared error (WMSE) metric. Applying this approximation to predict the WMSE-optimal tuning parameter for sparsity-based reconstruction, we are able to tune our parameter to achieve nearly MSE-optimal performance. In our simulations, we vary the noise level in the simulated data and use our Monte-Carlo method to tune the reconstruction to the noise level automatically.","Title: Globally convergent image reconstruction for emission tomography using relaxed ordered subsets algorithms.\nYear: 2003\n\nAbstract: We present two types of globally convergent relaxed ordered subsets (OS) algorithms for penalized-likelihood image reconstruction in emission tomography: modified block sequential regularized expectation-maximization (BSREM) and relaxed OS separable paraboloidal surrogates (OS-SPS). The global convergence proof of the existing BSREM (De Pierro and Yamagishi, 2001) required a few a posteriori assum...","Title: Undersampled Phase Retrieval with Outliers.\nYear: 2015\n\nAbstract: This paper proposes a general framework for reconstructing sparse images from undersampled (squared)magnitude data corrupted with outliers and noise. This phase retrieval method uses a layered approach, combining repeated minimization of a convex majorizer (surrogate for a nonconvex objective function), and iterative optimization of that majorizer using a preconditioned variant of the alternating ...","Title: Joint Design of Excitation k-Space Trajectory and RF Pulse for Small-Tip 3D Tailored Excitation in MRI.\nYear: 2016\n\nAbstract: We propose a new method for the joint design of k-space trajectory and RF pulse in 3D small-tip tailored excitation. Designing time-varying RF and gradient waveforms for a desired 3D target excitation pattern in MRI poses a non-linear, non-convex, constrained optimization problem with relatively large problem size that is difficult to solve directly. Existing joint pulse design approaches are therefore typically restricted to predefined trajectory types such as EPI or stack-of-spirals that intrinsically satisfy the gradient maximum and slew rate constraints and reduce the problem size (dimensionality) dramatically, but lead to suboptimal excitation accuracy for a given pulse duration. Here we use a 2nd-order B-spline basis that can be fitted to an arbitrary k-space trajectory, and allows the gradient constraints to be implemented efficiently. We show that this allows the joint optimization problem to be solved with quite general k-space trajectories. Starting from an arbitrary initial trajectory, we first approximate the trajectory using B-spline basis, and then optimize the corresponding coefficients. We evaluate our method in simulation using four different k-space initializations: stack-of-spirals, SPINS, KT-points, and a new method based on KT-points. In all cases, our approach leads to substantial improvement in excitation accuracy for a given pulse duration. We also validated our method for inner-volume excitation using phantom experiments. The computation is fast enough for online applications.","Title: Relaxed Linearized Algorithms for Faster X-Ray CT Image Reconstruction.\nYear: 2016\n\nAbstract: Statistical image reconstruction (SIR) methods are studied extensively for X-ray computed tomography (CT) due to the potential of acquiring CT scans with reduced X-ray dose while maintaining image quality. However, the longer reconstruction time of SIR methods hinders their use in X-ray CT in practice. To accelerate statistical methods, many optimization techniques have been investigated. Over-rel...","Title: Model-Based, One-Sided, Time-Of-Flight Terahertz Image Reconstruction\nYear: 2014\n\nAbstract: In the last decade, terahertz-mode imaging has received increased attention for non-destructive testing applications due to its ability to penetrate many materials while maintaining a small wavelength. This paper describes a model-based reconstruction algorithm that is able to image defects in the spray-on foam insulation (SOFT) used in aerospace applications that has been sprayed on a reflective metal hull. In this situation, X-ray based imaging is infeasible since only one side of the hull is accessible in flight.This paper models the object as a grid of materials, each section of which has a constant index of refraction. The delay between the transmission and reception of a THz pulse is related to the integral of the index of refraction along the pulse's path, and we adapt computed tomography (CT) methods to reconstruct an image of an object's index of refraction.We present the results of our reconstruction method using real data of the timing of THz pulses passing through a block of SOFT with holes of a known location and radius. The resulting image of the block has a low level of noise, but contains artifacts due to the limited angular range of one-sided imaging and due to the narrow beam approximation used in the forward model.","Title: Iterative Weighted Risk Estimation For Nonlinear Image Restoration With Analysis Priors\nYear: 2012\n\nAbstract: Image acquisition systems invariably introduce blur, which necessitates the use of deblurring algorithms for image restoration. Restoration techniques involving regularization require appropriate selection of the regularization parameter that controls the quality of the restored result. We focus on the problem of automatic adjustment of this parameter for nonlinear image restoration using analysis-type regularizers such as total variation (TV). For this purpose, we use two variants of Stein's unbiased risk estimate (SURE), Predicted-SURE and Projected-SURE, that are applicable for parameter selection in inverse problems involving Gaussian noise. These estimates require the Jacobian matrix of the restoration algorithm evaluated with respect to the data. We derive analytical expressions to recursively update the desired Jacobian matrix for a fast variant of the iterative reweighted least-squares restoration algorithm that can accommodate a variety of regularization criteria. Our method can also be used to compute a nonlinear version of the generalized cross-validation (NGCV) measure for parameter tuning. We demonstrate using simulations that Predicted-SURE, Projected-SURE, and NGCV-based adjustment of the regularization parameter yields near-MSE-optimal results for image restoration using TV, an analysis-type L-1-Regularization, and a smooth convex edge-preserving regularizer.","Title: Fast Edge-Preserving Image Denoising Via Group Coordinate Descent On The Gpu\nYear: 2014\n\nAbstract: We present group coordinate descent algorithms for edge-preserving image denoising that are particularly well-suited to the graphics processing unit (GPU). The algorithms decouple the denoising optimization problem into a set of iterated, independent one-dimensional problems. We provide methods to handle both differentiable regularizers and the absolute value function using the majorize-minimize technique. Specifically, we use quadratic majorizers with Huber curvatures for differentiable potentials and a duality approach for the absolute value function. Preliminary experimental results indicate that the algorithms converge remarkably quickly in time.","Title: Joint estimation of activity distribution and attenuation map for TOF-PET using alternating direction method of multiplier\nYear: 2016\n\nAbstract: Recent advances in TOF PET joint estimation of activity and attenuation showed that activity and attenuation can be determined up to a global constant scale without severe crosstalk. MLAA was first proposed to estimate activity and attenuation map simultaneously, and then MLACF was developed to estimate activity and attenuation compensation factor (ACF). MLAA incorporated prior knowledge on the zero attenuation value outside body area to determine global scalar, but was slow to converge. MLACF converged much faster than MLAA, but required knowing total activity level in advance. We propose a new optimization method based on variable splitting and alternating direction method of multiplier (MLADMM). Our proposed MLADMM achieved fast convergence rate comparable to MLACF without knowing total activity level. MLADMM also has a potential to use more sophisticated MR-based prior for attenuation in PET-MR.","Title: Low-rank and Adaptive Sparse Signal (LASSI) Models for Highly Accelerated Dynamic Imaging.\nYear: 2017\n\nAbstract: Sparsity-based approaches have been popular in many applications in image processing and imaging. Compressed sensing exploits the sparsity of images in a transform domain or dictionary to improve image recovery from undersampled measurements. In the context of inverse problems in dynamic imaging, recent research has demonstrated the promise of sparsity and low-rank techniques. For example, the pat...","Title: Fast Variance Prediction for Iteratively Reconstructed CT Images With Locally Quadratic Regularization.\nYear: 2017\n\nAbstract: Predicting noise properties of iteratively reconstructed CT images is useful for analyzing reconstruction methods; for example, local noise power spectrum (NPS) predictions may be used to quantify the detectability of an image feature, to design regularization methods, or to determine dynamic tube current adjustment during a CT scan. This paper presents a method for fast prediction of reconstructe...","Title: Towards a theoretical analysis of PCA for heteroscedastic data\nYear: 2016\n\nAbstract: Principal Component Analysis (PCA) is a method for estimating a subspace given noisy samples. It is useful in a variety of problems ranging from dimensionality reduction to anomaly detection and the visualization of high dimensional data. PCA performs well in the presence of moderate noise and even with missing data, but is also sensitive to outliers. PCA is also known to have a phase transition when noise is independent and identically distributed; recovery of the subspace sharply declines at a threshold noise variance. Effective use of PCA requires a rigorous understanding of these behaviors. This paper provides a step towards an analysis of PCA for samples with heteroscedastic noise, that is, samples that have non-uniform noise variances and so are no longer identically distributed. In particular, we provide a simple asymptotic prediction of the recovery of a one-dimensional subspace from noisy heteroscedastic samples. The prediction enables: a) easy and efficient calculation of the asymptotic performance, and b) qualitative reasoning to understand how PCA is impacted by heteroscedasticity (such as outliers).","Title: Detector Blur and Correlated Noise Modeling for Digital Breast Tomosynthesis Reconstruction.\nYear: 2018\n\nAbstract: This paper describes a new image reconstruction method for digital breast tomosynthesis (DBT). The new method incorporates detector blur into the forward model. The detector blur in DBT causes correlation in the measurement noise. By making a few approximations that are reasonable for breast imaging, we formulated a regularized quadratic optimization problem with a data-fit term that incorporates ...","Title: Efficient Sum of Outer Products Dictionary Learning (SOUP-DIL) - The $\\ell_0$ Method.\nYear: 2015\n\nAbstract: The sparsity of natural signals and images in a transform domain or dictionary has been extensively exploited in several applications such as compression, denoising and inverse problems. More recently, data-driven adaptation of synthesis dictionaries has shown promise in many applications compared to fixed or analytical dictionary models. However, dictionary learning problems are typically non-convex and NP-hard, and the usual alternating minimization approaches for these problems are often computationally expensive, with the computations dominated by the NP-hard synthesis sparse coding step. In this work, we investigate an efficient method for $\\ell_{0}$ \"norm\"-based dictionary learning by first approximating the training data set with a sum of sparse rank-one matrices and then using a block coordinate descent approach to estimate the unknowns. The proposed block coordinate descent algorithm involves efficient closed-form solutions. In particular, the sparse coding step involves a simple form of thresholding. We provide a convergence analysis for the proposed block coordinate descent approach. Our numerical experiments show the promising performance and significant speed-ups provided by our method over the classical K-SVD scheme in sparse signal representation and image denoising.","Title: Efficient, Convergent SENSE MRI Reconstruction for Nonperiodic Boundary Conditions via Tridiagonal Solvers.\nYear: 2017\n\nAbstract: Undersampling is an effective method for reducing scan acquisition time for MRI. Strategies for accelerated MRI, such as parallel MRI and compressed sensing MRI present challenging image reconstruction problems with nondifferentiable cost functions and computationally demanding operations. Variable splitting (VS) can simplify implementation of difficult image reconstruction problems, such as the c...","Title: LASSI: A low-rank and adaptive sparse signal model for highly accelerated dynamic imaging\nYear: 2016\n\nAbstract: Sparsity-based approaches have been popular in many applications in image processing and imaging. Recent research has shown the usefulness of sparsity or low-rank techniques for solving inverse problems such as those in dynamic imaging. In particular, the imaged temporal data sequence is modeled as a sum of low-rank and sparse components that are estimated from measurements. In this work, we instead decompose the temporal image sequence into a low-rank component and a component whose spatiotemporal patches are assumed sparse in some adaptive dictionary domain. We present a methodology to jointly estimate the underlying signal components and the spatiotemporal dictionary from highly under-sampled measurements. Our numerical experiments demonstrate the promising performance of our scheme for dynamic magnetic resonance image reconstruction from undersampled k-t space data.","Title: Low dose CT image reconstruction with learned sparsifying transform\nYear: 2017\n\nAbstract: A major challenge in computed tomography (CT) is to reduce X-ray dose to a low or even ultra-low level while maintaining the high quality of reconstructed images. We propose a new method for CT reconstruction that combines penalized weighted-least squares reconstruction (PWLS) with regularization based on a sparsifying transform (PWLS-ST) learned from a dataset of numerous CT images. We adopt an alternating algorithm to optimize the PWLS-ST cost function that alternates between a CT image update step and a sparse coding step. We adopt a relaxed linearized augmented Lagrangian method with ordered-subsets (relaxed OS-LALM) to accelerate the CT image update step by reducing the number of forward and backward projections. Numerical experiments on the XCAT phantom show that for low dose levels, the proposed PWLS-ST method dramatically improves the quality of reconstructed images compared to PWLS reconstruction with a nonadaptive edge-preserving regularizer (PWLS-EP).","Title: Efficient learning of dictionaries with low-rank atoms\nYear: 2016\n\nAbstract: Sparsity-based techniques have been popular in many applications in signal and image processing. In particular, the data-driven adaptation of sparse signal models such as the synthesis model has shown promise in applications. However, dictionary learning problems are typically nonconvex and NP-hard, and the usual alternating minimization approaches for learning are often expensive and lack convergence guarantees. In this work, we investigate efficient methods for learning structured synthesis dictionaries. In particular, we model the atoms (columns) of the dictionary, after reshaping, as low-rank. We propose a block coordinate descent algorithm for our dictionary learning model that involves efficient optimal updates. We also provide a convergence analysis of the proposed method for a highly nonconvex problem. Our numerical experiments show the usefulness of our schemes in inverse problem settings, such as in dynamic MRI and inpainting.","Title: Sum Of Outer Products Dictionary Learning For Inverse Problems\nYear: 2016\n\nAbstract: The data-driven adaptation of synthesis dictionaries has been exploited in many applications in signal processing and imaging. This paper exploits efficient methods for aggregate sparsity penalized dictionary learning by first approximating the matrix of image patches with a sum of sparse rank-one matrices (outer products) and then using a block coordinate descent approach to estimate the unknowns, and applies such sum of outer products methodologies for the problem of dictionary-blind image reconstruction. We propose efficient algorithms for adaptive image reconstruction and provide a convergence analysis for our methods. Our numerical experiments show the promising performance provided by the proposed schemes over recent methods in compressed sensing-based image reconstruction.","Title: Dictionary-free MRI parameter estimation via kernel ridge regression\nYear: 2017\n\nAbstract: MRI parameter quantification has diverse applications, but likelihood-based methods typically require nonconvex optimization due to nonlinear signal models. To avoid expensive grid searches used in prior works, we propose to learn a nonlinear estimator from simulated training examples and (approximate) kernel ridge regression. As proof of concept, we apply kernel-based estimation to quantify six parameters per voxel describing the steady-state magnetization dynamics of two water compartments from simulated data. In relevant regions of fast-relaxing compartmental fraction estimates, kernel estimation achieves comparable mean-squared error as grid search, with dramatically reduced computation.","Title: Convolutional Dictionary Learning: Acceleration and Convergence.\nYear: 2018\n\nAbstract: Convolutional dictionary learning (CDL or sparsifying CDL) has many applications in image processing and computer vision. There has been growing interest in developing efficient algorithms for CDL, mostly relying on the augmented Lagrangian (AL) method or the variant alternating direction method of multipliers (ADMM). When their parameters are properly tuned, AL methods have shown fast convergence...","Title: Challenges and Open Problems in Signal Processing: Panel Discussion Summary from ICASSP 2017 [Panel and Forum].\nYear: 2017\n\nAbstract: This column summarizes the panel on open problems in signal processing, which took place on 5 March 2017 at the International Conference on Acoustics, Speech, and Signal Processing (ICASSP) in New Orleans, Louisiana. The goal of the panel was to draw attention to some of the challenges and open problems in various areas of signal processing and generate discussion on future research areas that can...","Title: Efficient Sum of Outer Products Dictionary Learning (SOUP-DIL) and Its Application to Inverse Problems.\nYear: 2017\n\nAbstract: The sparsity of signals in a transform domain or dictionary has been exploited in applications, such as compression, denoising, and inverse problems. More recently, data-driven adaptation of synthesis dictionaries has shown promise compared to analytical dictionary models. However, dictionary learning problems are typically nonconvex and NP-hard, and the usual alternating minimization approaches f...","Title: Adaptive sparse modeling and shifted-poisson likelihood based approach for low-dosect image reconstruction\nYear: 2017\n\nAbstract: Recent research in computed tomographic imaging has focused on developing techniques that enable reduction of the X-ray radiation dose without loss of quality of the reconstructed images or volumes. While penalized weighted-least squares (PWLS) approaches have been popular for CT image reconstruction, their performance degrades for very low dose levels due to the inaccuracy of the underlying WLS statistical model. We propose a new formulation for low-dose CT image reconstruction based on a shifted-Poisson model based likelihood function and a data-adaptive regularizer using the sparsifying transform model for images. The sparsifying transform is pre-learned from a dataset of patches extracted from CT images. The nonconvex cost function of the proposed penalized-likelihood reconstruction with sparsifying transforms regularizer (PL-ST) is optimized by alternating between a sparse coding step and an image update step. The image update step deploys a series of convex quadratic majorizers that are optimized using a relaxed linearized augmented Lagrangian method with ordered-subsets, reducing the number of (expensive) forward and backward projection operations. Numerical experiments show that for low dose levels, the proposed data-driven PL-ST approach outperforms prior methods employing a nonadaptive edge-preserving regularizer. PL-ST also outperforms prior PWLS-ST approach at very low X-ray doses.","Title: Fast Spatial Resolution Analysis of Quadratic Penalized Least-Squares Image Reconstruction With Separate Real and Imaginary Roughness Penalty: Application to fMRI.\nYear: 2018\n\nAbstract: Penalized least-squares iterative image reconstruction algorithms used for spatial resolution-limited imaging, such as functional magnetic resonance imaging (fMRI), commonly use a quadratic roughness penalty to regularize the reconstructed images. When used for complex-valued images, the conventional roughness penalty regularizes the real and imaginary parts equally. However, these imaging methods...","Title: Image Reconstruction for Limited-Angle Electron Beam X-Ray Computed Tomography With Energy-Integrating Detectors for Multiphase Flows.\nYear: 2018\n\nAbstract: We propose a new iterative X-ray computed tomography (CT) reconstruction algorithm for electron beam X-ray tomography of multiphase flows in metal pipes. This application uses limited-angle projections due to the fixed configuration, and semiconductor-type energy-integrating detectors. For the data-fitting objective function, the proposed method incorporates a nonlinear Gaussian model with object-...","Title: Online dynamic MRI reconstruction via robust subspace tracking.\nYear: 2017\n\nAbstract: We propose an efficient online reconstruction algorithm for the problem of highly undersampled dynamic magnetic resonance imaging (DMRI). Our approach reconstructs the dynamic time series by processing only a small batch of frames at a time. We adapt an online subspace tracking algorithm based on manifold optimization to the DMRI reconstruction setting and propose a novel extension of the algorithm to enable robust subspace tracking based on a local low-rank plus transform sparse model. Our experiments on real and synthetic data show that proposed approach gives comparable results to methods that reconstruct the entire image series at once while requiring only a fraction of the memory and computational demand. The dramatic memory savings allows robust subspace-based methods to be applied to much larger datasets than previously allowed.","Title: Convolutional Analysis Operator Learning: Acceleration, Convergence, Application, and Neural Networks.\nYear: 2018\n\nAbstract: Convolutional operator learning is increasingly gaining attention in many signal processing and computer vision applications. Learning kernels has mostly relied on so-called local approaches that extract and store many overlapping patches across training signals. Due to memory demands, local approaches have limitations when learning kernels from large datasets -- particularly with multi-layered structures, e.g., convolutional neural network (CNN) -- and/or applying the learned kernels to high-dimensional signal recovery problems. The so-called global approach has been studied within the synthesis signal model, e.g., convolutional dictionary learning, overcoming the memory problems by careful algorithmic designs. This paper proposes a new convolutional analysis operator learning (CAOL) framework in the global approach, and develops a new convergent Block Proximal Gradient method using a Majorizer (BPG-M) to solve the corresponding block multi-nonconvex problems. To learn diverse filters within the CAOL framework, this paper introduces an orthogonality constraint that enforces a tight-frame (TF) filter condition, and a regularizer that promotes diversity between filters. Numerical experiments show that, for tight majorizers, BPG-M significantly accelerates the CAOL convergence rate compared to the state-of-the-art method, BPG. Numerical experiments for sparse-view computational tomography show that CAOL using TF filters significantly improves reconstruction quality compared to a conventional edge-preserving regularizer. Finally, this paper shows that CAOL can be useful to mathematically model a CNN, and the corresponding updates obtained via BPG-M coincide with core modules of the CNN.","Title: Accelerated high b-value diffusion-weighted MR imaging via phase-constrained low-rank tensor model\nYear: 2018\n\nAbstract: High b-value Diffusion-weighted MRI (DWI) is promising in cancer imaging but suffers from long acquisition time and low signal-to-noise ratio (SNR). We propose a low-rank tensor model that exploits correlation across both diffusion-induced signal decays and neighboring k-space samples, to accelerate the acquisition of DWI using an extended range of b-values (0 s/mm\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\n to 2500 s/mm\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\n) and limited (orthogonal only) diffusion directions, an imaging scheme that is increasingly used for brain gliomas evaluation. A phase constraint accounts for phase variations between b-values is also applied. Our method integrates parallel imaging and partial Fourier acquisition naturally, and undersamples along phase-encoding direction only. Reconstruction results using both patient and simulated data with an acceleration factor of 8 show improved SNR and reduced aliasing, as compared to parallel imaging only method as well as two other low-rank model-based methods.","Title: Accelerated methods for low-rank plus sparse image reconstruction\nYear: 2018\n\nAbstract: The low-rank plus sparse (L+S) decomposition model enables the reconstruction of undersampled dynamic magnetic resonance imaging (MRI) data. Solving for the L and S components is anonsmooth composite convex minimization problem. While current techniques for this model are based on the classical iterative soft thresholding algorithm (ISTA), accelerated methods can be applied to obtain faster rate of convergence of the algorithm. This paper proposes two alternative methods for solving the L+S problem, one based on the fast iterative shrinkage-thresholding algorithm (FISTA), and the other based on the recent proximal optimized gradient method (POGM). Numerical results suggest faster convergence than the traditional ISTA, while preserving its computational simplicity.","Title: Image-domain material decomposition using data-driven sparsity models for dual-energy CT\nYear: 2018\n\nAbstract: Penalized weighted least squares (PWLS) with better image priors is a promising way to develop improved image-domain dual-energy CT (DECT) methods for achieving high quality basis material images. We propose a new method for DECT that combines conventional PWLS estimation with regularization based on sparsifying transforms (DECT-ST) learned from datasets of numerous CT images. Numerical experiments with phantom and patient data show that the proposed method significantly improves the image quality over direct matrix inversion decomposition and over PWLS decomposition with an edge-preserving hyperbola regularizer (DECT-EP).","Title: Another Look at the Fast Iterative Shrinkage/Thresholding Algorithm (FISTA).\nYear: 2018\n\nAbstract: This paper provides a new way of developing the fast iterative shrinkage/thresholding algorithm (FISTA) [A. Beck and M. Teboulle, SIAM T. Imaging Sci., 2 (2009), pp. 183-202] that is widely used for minimizing composite convex functions with a nonsmooth term such as the l(1) regularizer. In particular, this paper shows that FISTA corresponds to an optimized approach to accelerating the proximal gradient method with respect to a worst-case bound of the cost function. This paper then proposes a new algorithm that is derived by instead optimizing the step coefficients of the proximal gradient method with respect to a worst-case bound of the composite gradient mapping. The proof is based on the worst-case analysis called the performance estimation problem in [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482].","Title: PWLS-ULTRA: An Efficient Clustering and Learning-Based Approach for Low-Dose 3D CT Image Reconstruction.\nYear: 2018\n\nAbstract: The development of computed tomography (CT) image reconstruction methods that significantly reduce patient radiation exposure, while maintaining high image quality is an important area of research in low-dose CT imaging. We propose a new penalized weighted least squares (PWLS) reconstruction method that exploits regularization based on an efficient Union of Learned TRAnsforms (PWLS-ULTRA). The uni...","Title: Image Reconstruction is a New Frontier of Machine Learning.\nYear: 2018\n\nAbstract: Over past several years, machine learning, or more generally artificial intelligence, has generated overwhelming research interest and attracted unprecedented public attention. As tomographic imaging researchers, we share the excitement from our imaging perspective [item 1) in the Appendix], and organized this special issue dedicated to the theme of “Machine learning for image reconstruction.” Thi...","Title: Adaptive Restart of the Optimized Gradient Method for Convex Optimization.\nYear: 2018\n\nAbstract: First-order methods with momentum, such as Nesterov’s fast gradient method, are very useful for convex optimization problems, but can exhibit undesirable oscillations yielding slow convergence rates for some applications. An adaptive restarting scheme can improve the convergence rate of the fast gradient method, when the parameter of a strongly convex cost function is unknown or when the iterates of the algorithm enter a locally strongly convex region. Recently, we introduced the optimized gradient method, a first-order algorithm that has an inexpensive per-iteration computational cost similar to that of the fast gradient method, yet has a worst-case cost function rate that is twice faster than that of the fast gradient method and that is optimal for large-dimensional smooth convex problems. Building upon the success of accelerating the fast gradient method using adaptive restart, this paper investigates similar heuristic acceleration of the optimized gradient method. We first derive a new first-order method that resembles the optimized gradient method for strongly convex quadratic problems with known function parameters, yielding a linear convergence rate that is faster than that of the analogous version of the fast gradient method. We then provide a heuristic analysis and numerical experiments that illustrate that adaptive restart can accelerate the convergence of the optimized gradient method. Numerical results also illustrate that adaptive restart is helpful for a proximal version of the optimized gradient method for nonsmooth composite convex functions.","Title: Asymptotic performance of PCA for high-dimensional heteroscedastic data.\nYear: 2018\n\nAbstract: Principal Component Analysis (PCA) is a classical method for reducing the dimensionality of data by projecting them onto a subspace that captures most of their variation. Effective use of PCA in modern applications requires understanding its performance for data that are both high-dimensional and heteroscedastic. This paper analyzes the statistical performance of PCA in this setting, i.e., for high-dimensional data drawn from a low-dimensional subspace and degraded by heteroscedastic noise. We provide simplified expressions for the asymptotic PCA recovery of the underlying subspace, subspace amplitudes and subspace coefficients; the expressions enable both easy and efficient calculation and reasoning about the performance of PCA. We exploit the structure of these expressions to show that, for a fixed average noise variance, the asymptotic recovery of PCA for heteroscedastic data is always worse than that for homoscedastic data (i.e., for noise variances that are equal across samples). Hence, while average noise variance is often a practically convenient measure for the overall quality of data, it gives an overly optimistic estimate of the performance of PCA for heteroscedastic data.","Title: Dictionary-Free MRI PERK: Parameter Estimation via Regression with Kernels.\nYear: 2018\n\nAbstract: This paper introduces a fast, general method for dictionary-free parameter estimation in quantitative magnetic resonance imaging (QMRI) parameter estimation via regression with kernels (PERK). PERK first uses prior distributions and the nonlinear MR signal model to simulate many parameter-measurement pairs. Inspired by machine learning, PERK then takes these parameter-measurement pairs as labeled ...","Title: Learning Dictionary-Based Unions of Subspaces for Image Denoising.\nYear: 2018\n\nAbstract: Many signals of interest are well-approximated by sparse linear combinations of atomic signals from a dictionary. Equivalently, they are well-approximated by low-dimensional subspaces in a union of subspaces generated by the dictionary. A given sparsity level has an associated union of subspaces (UoS) generated by sparse combinations of correspondingly many atoms. When considering a sequence of sparsity levels, we have a sequence of unions of subspaces (SUoS) of increasing dimension. This paper considers the problem of learning such an SUoS from data. While each UoS is combinatorially large with respect to sparsity level, our learning approach exploits the fact that sparsity is structured for many signals of interest, i.e., that certain collections of atoms are more frequently used together than others. This is known as group sparsity structure and has been studied extensively when the structure is known a priori. We consider the setting where the structure is unknown, and we seek to learn it from training data. We also adapt the subspaces we obtain to improve representation and parsimony, similar to the goal of adapting atoms in dictionary learning. We illustrate the benefits of the learned dictionary-based SUoS for the problem of denoising; using a more parsimonious and representative SUoS results in improved recovery of complicated structures and edges.","Title: Real-Time Filtering with Sparse Variations for Head Motion in Magnetic Resonance Imaging.\nYear: 2019\n\nAbstract: •Sparse residual image modeling adapts Kalman filtering to temporal dynamics.•Augmented Lagrangian optimization can produce motion estimates in real time.•Adapting the process covariance estimate can improve handling of large motions.•Simulations depict improved brain activity detection with prospective correction.","Title: Fast and convergent iterative image recovery using trained convolutional neural networks.\nYear: 2018\n\nAbstract: Deep image mapping networks have been recently applied to solving some inverse problems in imaging due to their good mapping capabilities. However, the greater mapping capability can increase the chance of causing some artificial features when test images differ from training images. Combining image mapping networks with an iterative image recovery that naturally considers imaging system physics is an alternative approach to solving inverse problems. This alternative approach can avoid artificial features, by (back-)projecting the output signals of image mapping networks while considering the imaging system physics. By generalizing the state-of-the-art iterative image recovery algorithm using learned regularizer with iteration-wise image mapping networks, this paper proposes a new recurrent convolutional neural network, Momentum-Net. In addition, this paper investigates the theoretical convergence behavior of Momentum-Net. Numerical experiments show that, for ${a}$) denoising low signal-to-noise-ratio images, and ${b}$) sparse-view X-ray computed tomography, the proposed Momentum-Net achieves significantly more accurate and faster image recovery, compared to the state-of-the-art data-driven regularizer or the unsupervised autoencoding regularizer.","Title: Efficient Dynamic Parallel MRI Reconstruction for the Low-Rank Plus Sparse Model\nYear: 2019\n\nAbstract: The low-rank plus sparse (L+S) decomposition model enables the reconstruction of undersampled dynamic parallel magnetic resonance imaging data. Solving for the low rank and the sparse components involves nonsmooth composite convex optimization, and algorithms for this problem can be categorized into proximal gradient methods and variable splitting methods. This paper investigates new efficient algorithms for both schemes. While current proximal gradient techniques for the L+S model involve the classical iterative soft thresholding algorithm (ISTA), this paper considers two accelerated alternatives, one based on the fast iterative shrinkage-thresholding algorithm (FISTA) and the other with the recent proximal optimized gradient method (POGM). In the augmented Lagrangian (AL) framework, we propose an efficient variable splitting scheme based on the form of the data acquisition operator, leading to simpler computation than the conjugate gradient approach required by existing AL methods. Numerical results suggest faster convergence of the efficient implementations for both frameworks, with POGM providing the fastest convergence overall and the practical benefit of being free of algorithm tuning parameters.","Title: LEARNED MIXED MATERIAL MODELS FOR EFFICIENT CLUSTERING BASED DUAL-ENERGY CT IMAGE DECOMPOSITION\nYear: 2018\n\nAbstract: Penalized weight-least squares (PWLS) with basis material priors is a promising way to achieve high quality material decompositions for Dual-energy CT (DECT). This paper proposes a new method dubbed DECT-MULTRA for image domain DECT material decomposition that combines conventional PWLS estimation with regular-ization based on a mixed union of learned transforms (MULTRA) model. Our approach pre-learns from training data a common union of unitary transforms for all the basis materials’ patches, as well as a cross-material union of unitary transforms that captures relationships between the different basis material images. The proposed DECT-MULTRA algorithm efficiently obtains material decompositions by alternating between updating the material images and performing clustering of patches in the MULTRA model. Both these steps of the alternating algorithm have closed-form updates. Numerical experiments with the XCAT phantom show that the proposed method significantly improves image quality compared to the recent DECT-ST method that learns different sparsifying transforms for different basis materials and the DECT-EP approach that uses a non-adaptive edge-preserving hyperbola regularizer.","Title: Convolutional analysis operator learning - Application to sparse-view CT - (Invited Paper).\nYear: 2018\n\nAbstract: Convolutional analysis operator learning (CAOL) methods train an autoencoding convolutional neural network (CNN) in an unsupervised learning manner, to more accurately solve inverse problems. Block Proximal Gradient method using a Majorizer (BPG-M) achieved fast and convergent CAOL, by using sharp majorizers and the momentum terms. This paper proposes a model-based image reconstruction (MBIR) method using autoencoding CNNs trained via CAOL, for sparse-view computational tomography (CT). We apply BPG-M to rapidly and stably solve the corresponding block multi-nonconvex optimization problem. Numerical experiments show that, for sparse-view CT, 1) the proposed MBIR method outperforms the standard MBIR method using edge-preserving regularization; 2) larger parameter dimensions of autoencoding CNNs improve reconstruction accuracy of the proposed MBIR method; and 3) when using BPG-M, sharper majorization is more critical for accelerating its convergence than giving more weights on extrapolation.","Title: Generalizing the Optimized Gradient Method for Smooth Convex Minimization.\nYear: 2018\n\nAbstract: This paper generalizes the optimized gradient method (OGM) [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482], [D. Kim and J. A. Fessler, Math. Program., 159 (2016), pp. 81-107], [D. Kim and J. A. Fessler, J. Optim. Theory Appl., 172 (2017), pp. 187205] that achieves the optimal worst-case cost function bound of first-order methods for smooth convex minimization [Y. Drori, J. Complexity, 39 (2017), pp. 1-16]. Specifically, this paper studies a generalized formulation of OGM and analyzes its worst-case rates in terms of both the function value and the norm of the function gradient. This paper also develops a new algorithm called OGM-OG that is in the generalized family of OGM and that has the best known analytical worst-case bound with rate O(1/N-1.5) on the decrease of the gradient norm among fixed-step first-order methods. This paper also proves that Nesterov's fast gradient method [Y. Nesterov, Dokl. Akad. Nauk. USSR, 269 (1983), pp. 543-547], [Y. Nesterov, Math. Program., 103 (2005), pp. 127-152] has an O(1/N-1.5) worst-case gradient norm rate but with constant larger than OGM-OG. The proof is based on the worst-case analysis called the Performance Estimation Problem in [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482].","Title: Deep Dictionary-Transform Learning For Image Reconstruction\nYear: 2018\n\nAbstract: Various dictionaries and transforms are known to sparsify images, and have been exploited in algorithms for image reconstruction from limited data. Methods that simultaneously reconstruct the image and learn dictionaries or sparsifying transforms for image patches, called blind compressed sensing methods, have shown promising performance. Motivated by such adaptive algorithms, this paper proposes an approach to train dictionary-transform based methods for image reconstruction by minimizing a minimum absolute reconstruction error criterion. Each \"layer\" of the algorithm consists of applying (convolving) trained transforms, thresholdings, and dictionaries to images, followed by a simple least squares update of the images. Numerical experiments illustrate the usefulness and speed-ups provided by such trained algorithms compared to related schemes.","Title: DECT-MULTRA: Dual-Energy CT Image Decomposition With Learned Mixed Material Models and Efficient Clustering.\nYear: 2019\n\nAbstract: Dual-energy computed tomography (DECT) imaging plays an important role in advanced imaging applications due to its material decomposition capability. Image-domain decomposition operates directly on CT images using linear matrix inversion, but the decomposed material images can be severely degraded by noise and artifacts. This paper proposes a new method dubbed DECT-MULTRA for image-domain DECT material decomposition that combines conventional penalized weighted-least squares (PWLS) estimation with regularization based on a mixed union of learned transforms (MULTRA) model. Our proposed approach pre-learns a union of common-material sparsifying transforms from patches extracted from all the basis materials, and a union of cross-material sparsifying transforms from multi-material patches. The common-material transforms capture the common properties among different material images, while the cross-material transforms capture the cross-dependencies. The proposed PWLS formulation is optimized efficiently by alternating between an image update step and a sparse coding and clustering step, with both of these steps having closed-form solutions. The effectiveness of our method is validated with both XCAT phantom and clinical head data. The results demonstrate that our proposed method provides superior material image quality and decomposition accuracy compared to other competing methods.","Title: Optimizing MRF-ASL Scan Design for Precise Quantification of Brain Hemodynamics using Neural Network Regression.\nYear: 2019\n\nAbstract: Purpose Arterial Spin Labeling (ASL) is a quantitative, non-invasive alternative for perfusion imaging that does not use contrast agents. The magnetic resonance fingerprinting (MRF) framework can be adapted to ASL to estimate multiple physiological parameters simultaneously. In this work, we introduce an optimization scheme to increase the sensitivity of the ASL fingerprint. We also propose a regression based estimation framework for MRF-ASL. Methods To improve the sensitivity of MRF-ASL signals to underlying parameters, we optimized ASL labeling durations using the Cramer-Rao Lower Bound (CRLB). This paper also proposes a neural network regression based estimation framework trained using noisy synthetic signals generated from our ASL signal model. We tested our methods in silico and in vivo, and compared with multiple post labeling delay (multi-PLD) ASL and unoptimized MRF-ASL. We present comparisons of estimated maps for the six parameters of our signal model. Results The scan design process facilitated precise estimates of multiple hemodynamic parameters and tissue properties from a single scan, in regions of normal gray and white matter, as well as regions with anomalous perfusion activity in the brain. In particular, there was a 86.7% correlation of perfusion estimates with the ground truth in silico, using our proposed techniques. In vivo, there was roughly a 7 fold improvement in the Coefficient of Variation (CoV) for white matter perfusion, and 2 fold improvement in gray matter perfusion CoV in comparison to a reference Multi PLD method. The regression based estimation approach provided perfusion estimates rapidly, with estimation times of around 1s per map. Conclusions Scan design optimization, coupled with regression-based estimation is a powerful tool for improving precision in MRF-ASL","Title: Simplified Statistical Image Reconstruction for X-ray CT with Beam-Hardening Artifact Compensation.\nYear: 2020\n\nAbstract: CT images are often affected by beam-hardening artifacts due to the polychromatic nature of the X-ray spectra. These artifacts appear in the image as cupping in homogeneous areas and as dark bands between dense regions such as bones. This paper proposes a simplified statistical reconstruction method for X-ray CT based on Poisson statistics that accounts for the non-linearities caused by beam hardening. The main advantages of the proposed method over previous algorithms are that it avoids the preliminary segmentation step, which can be tricky, especially for low-dose scans, and it does not require knowledge of the whole source spectrum, which is often unknown. Each voxel attenuation is modeled as a mixture of bone and soft tissue by defining density-dependent tissue fractions and maintaining one unknown per voxel. We approximate the energy-dependent attenuation corresponding to different combinations of bone and soft tissues, the so-called beam-hardening function, with the 1D function corresponding to water plus two parameters that can be tuned empirically. Results on both simulated data with Poisson sinogram noise and two rodent studies acquired with the ARGUS/CT system showed a beam hardening reduction (both cupping and dark bands) similar to analytical reconstruction followed by post-processing techniques but with reduced noise and streaks in cases with a low number of projections, as expected for statistical image reconstruction.","Title: Improved low-count quantitative PET reconstruction with a variational neural network.\nYear: 2019\n\nAbstract: Image reconstruction in low-count PET is particularly challenging because gammas from natural radioactivity in Lu-based crystals cause high random fractions that lower the measurement signal-to-noise-ratio (SNR). In model-based image reconstruction (MBIR), using more iterations of an unregularized method may increase the noise, so incorporating regularization into the image reconstruction is desirable to control the noise. New regularization methods based on learned convolutional operators are emerging in MBIR. We modify the architecture of a variational neural network, BCD-Net, for PET MBIR, and demonstrate the efficacy of the trained BCD-Net using XCAT phantom data that simulates the low true coincidence count-rates with high random fractions typical for Y-90 PET patient imaging after Y-90 microsphere radioembolization. Numerical results show that the proposed BCD-Net significantly improves PET reconstruction performance compared to MBIR methods using non-trained regularizers, total variation (TV) and non-local means (NLM), and a non-MBIR method using a single forward pass deep neural network, U-Net. BCD-Net improved activity recovery for a hot sphere significantly and reduced noise, whereas non-trained regularizers had a trade-off between noise and quantification. BCD-Net improved CNR and RMSE by 43.4% (85.7%) and 12.9% (29.1%) compared to TV (NLM) regularized MBIR. Moreover, whereas the image reconstruction results show that the non-MBIR U-Net over-fits the training data, BCD-Net successfully generalizes to data that differs from training data. Improvements were also demonstrated for the clinically relevant phantom measurement data where we used training and testing datasets having very different activity distribution and count-level.","Title: Efficient Multi-GPU Shared Memory via Automatic Optimization of Fine-Grained Transfers\nYear: 2021\n\nAbstract: Despite continuing research into inter-GPU communication mechanisms, extracting performance from multi-GPU systems remains a significant challenge. Inter-GPU communication via bulk DMA-based transfers exposes data transfer latency on the GPU’s critical execution path because these large transfers are logically interleaved between compute kernels. Conversely, fine-grained peer-to-peer memory accesses during kernel execution lead to memory stalls that can exceed the GPUs’ ability to cover these operations via multi-threading. Worse yet, these sub-cacheline transfers are highly inefficient on current inter-GPU interconnects. To remedy these issues, we propose PROACT, a system enabling remote memory transfers with the programmability and pipeline advantages of peer-to-peer stores, while achieving interconnect efficiency that rivals bulk DMA transfers. Combining compile-time instrumentation with fine-grain tracking of data block readiness within each GPU, PROACT enables interconnect-friendly data transfers while hiding the transfer latency via pipelining during kernel execution. This work describes both hardware and software implementations of PROACT and demonstrates the effectiveness of a PROACT software prototype on three generations of GPU hardware and interconnects. Achieving near-ideal interconnect efficiency, PROACT realizes a mean speedup of 3.0× over single-GPU performance for 4-GPU systems, capturing 83% of available performance opportunity. On a 16-GPU NVIDIA DGX-2 system, we demonstrate an 11.0× average strong-scaling speedup over single-GPU performance, 5.3× better than a bulk DMA-based approach.","Title: Jigsaw: A Slice-and-Dice Approach to Non-uniform FFT Acceleration for MRI Image Reconstruction\nYear: 2021\n\nAbstract: The Fast Fourier Transform (FFT) is a fundamental algorithm in signal processing; significant efforts have been made to improve its performance using software optimizations and specialized hardware accelerators. Computational imaging modalities, such as MRI, often rely on the Non-uniform Fast Fourier Transform (NuFFT), a variant of the FFT for processing data acquired from non-uniform sampling pat...","Title: Bilevel Methods for Image Reconstruction.\nYear: 2022\n\nAbstract: This review discusses methods for learning parameters for image reconstruction problems using bilevel formulations. Image reconstruction typically involves optimizing a cost function to recover a vector of unknown variables that agrees with collected measurements and prior assumptions. State-of-the-art image reconstruction methods learn these prior assumptions from training data using various machine learning techniques, such as bilevel methods. One can view the bilevel problem as formalizing hyperparameter optimization, as bridging machine learning and cost function based optimization methods, or as a method to learn variables best suited to a specific task. More formally, bilevel problems attempt to minimize an upper-level loss function, where variables in the upper-level loss function are themselves minimizers of a lower-level cost function. This review contains a running example problem of learning tuning parameters and the coefficients for sparsifying filters used in a regularizer. Such filters generalize the popular total variation regularization method, and learned filters are closely related to convolutional neural networks approaches that are rapidly gaining in popularity. Here, the lower-level problem is to reconstruct an image using a regularizer with learned sparsifying filters; the corresponding upper-level optimization problem involves a measure of reconstructed image quality based on training data. This review discusses multiple perspectives to motivate the use of bilevel methods and to make them more easily accessible to different audiences. We then turn to ways to optimize the bilevel problem, providing pros and cons of the variety of proposed approaches. Finally we overview bilevel applications in image reconstruction.","Title: Poisson Phase Retrieval in Very Low-Count Regimes\nYear: 2022\n\nAbstract: This paper proposes novel phase retrieval algorithms for maximum likelihood (ML) estimation from measurements following independent Poisson distributions in very low-count regimes, e.g., 0.25 photon per pixel. Specifically, we propose a modified Wirtinger flow (WF) algorithm using a step size based on the observed Fisher information. This approach eliminates all parameter tuning except the number of iterations. We also propose a novel curvature for majorize-minimize (MM) algorithms with a quadratic majorizer. We show theoretically that our proposed curvature is sharper than the curvature derived from the supremum of the second derivative of the Poisson ML cost function. We compare the proposed algorithms (WF, MM) with existing optimization methods, including WF using other step-size schemes, quasi-Newton methods and alternating direction method of multipliers (ADMM) algorithms, under a variety of experimental settings. Simulation experiments with a random Gaussian matrix, a canonical discrete Fourier transform (DFT) matrix, a masked DFT matrix and an empirical transmission matrix demonstrate the following. 1) As expected, algorithms based on the Poisson ML model consistently produce higher quality reconstructions than algorithms derived from Gaussian noise ML models when applied to low-count data. 2) For unregularized cases, our proposed WF algorithm with Fisher information for step size converges faster than other WF methods, e.g., WF with empirical step size, backtracking line search, and optimal step size for the Gaussian noise model; it also converges faster than the quasi-Newton method. 3) In regularized cases, our proposed WF algorithm converges faster than WF with backtracking line search, quasi-Newton, MM and ADMM."],"string":"[\n \"Title: Cross-validation and predicted risk estimation for nonlinear iterative reweighted least-squares MRI reconstruction.\\nYear: 2012\\n\\nAbstract: Regularization is an effective means of reducing noise and artifacts in MR image reconstruction from undersampled k-space data. Proper application of regularization demands appropriate selection of the associated regularization parameter. Generalized cross-validation (GCV) is a popular parameter tuning technique especially for linear reconstruction methods, but its application to nonlinear iterative MRI reconstruction is more involved as it demands the evaluation of the Jacobian matrix of the reconstruction algorithm with respect to complex-valued data. We derive analytical expressions for recursively updating this Jacobian matrix for an iterative reweighted least-squares reconstruction algorithm. Our method can also be used to calculate a predicted risk estimate (PSURE) for MRI based on Stein's principle. We demonstrate with simulations and experiments with real data that regularization parameter selection based on GCV and PSURE provides near-MSE-optimal results for nonlinear MRI reconstruction from undersampled k-space data using l(1)-regularization.\",\n \"Title: Asymptotic Source Detection Performance of Gamma-Ray Imaging Systems Under Model Mismatch\\nYear: 2011\\n\\nAbstract: Likelihood-based test statistics for the task of detecting a radioactive source in background using a gamma-ray imaging system often have intractable distributions. This complicates the tasks of predicting detection performance and setting thresholds that ensure desired false-alarm rates. Asymptotic distributions of test statistics can aid in predicting performance and in setting detection thresholds. However, in applications with complex sensors, like gamma-ray imaging, often only approximate statistical models for the measurements are available. Standard asymptotic approximations can yield inaccurate performance predictions when based on misspecified models. This paper considers asymptotic properties of detection tests based on maximum likelihood (ML) estimates under model mismatch, i.e., when the statistical model used for detection differs from the true distribution. We provide general expressions for the asymptotic distribution of likelihood-based test statistics when the number of measurements is Poisson, and expressions specific to gamma-ray source detection that one can evaluate using a modest amount of data from a real system or Monte Carlo simulation. Considering a simulated Compton imaging system, we show that the proposed expressions yield more accurate detection performance predictions than previous expressions that ignore model mismatch. These expressions require less data and computation than conventional empirical methods.\",\n \"Title: Respiratory Motion Estimation From Slowly Rotating X-Ray Projections\\nYear: 2004\\n\\nAbstract: As radiotherapy has become increasingly conformal, geometric uncertainties caused by breathing and organ motion have become an important issue. Accurate motion estimates may lead to improved treatment planning and dose calculation in radiation therapy. However, respiratory motion is difficult to study by conventional X-ray CT imaging since object motion causes inconsistent projection views leading to artifacts in reconstructed images.We propose to estimate the parameters of a nonrigid motion model from a set of projection views of the thorax that are acquired using a slowly rotating cone-beam CT scanner, such as a radiotherapy simulator. We use a conventionally reconstructed 3D thorax image, acquired by breath-hold CT, as a reference volume. We represent respiratory motion using a flexible parametric nonrigid motion model based on B-splines. The motion parameters are estimated by optimizing a regularized cost function that includes the squared error between the measured projection views and the reprojections of the deformed reference image. Preliminary 2D simulation results show that there is good agreement between the estimated motion and the true motion.\",\n \"Title: New Statistical Models for Randoms-Precorrected PET Scans\\nYear: 1997\\n\\nAbstract: PET measurements are usually precorrected for accidental coincidence events by real-time subtraction of the delayed window coincidences. Randoms subtraction compensates in mean for accidental coincidences but destroys the Poisson statistics. We propose and analyze two new approximations to the exact log-likelihood of the precorrected measurements, one based on a \\\"shifted Poisson\\\" model, the other based on saddle-point approximations to the measurement probability mass function (pmf). The methods apply to both emission and transmission tomography; however in this paper we focus on transmission tomography. We compare the new models to conventional data-weighted least squares (WLS) and conventional maximum likelihood (based on the ordinary Poisson (OP) model) using simulations and analytic approximations. The results demonstrate that the proposed methods avoid the systematic bias of the WLS method, and lead to significantly lower variance than the conventional OP method. The saddle-point method provides a more accurate approximation to the exact log-likelihood than the WLS, OP and shifted Poisson alternatives. However, the simpler shifted Poisson method yielded comparable bias-variance performance in the simulations. The new methods offer improved image reconstruction in PET through more realistic statistical modeling, yet with negligible increase in computation over the conventional OP method.\",\n \"Title: Analytical Approach to Channelized Hotelling Observer Performance For Regularized Tomographic Image Reconstruction\\nYear: 2004\\n\\nAbstract: Our goal is to analyze regularized image reconstruction meth- ods such as penalized likelihood with respect to the perfor- mance of the Channelized Hotelling Observer (CHO) in the task of detecting a small target signal in the reconstructed images, in the presence of a correlated random background. We derive here an approximation to the performance of the CHO by working entirely with continuous-space formula- tions and then discretizing the nal result. This approach leads to an extension and a renement of approximations that we previously derived in the discrete space.\",\n \"Title: Accelerated Regularized Estimation of MR Coil Sensitivities Using Augmented Lagrangian Methods.\\nYear: 2013\\n\\nAbstract: Several magnetic resonance parallel imaging techniques require explicit estimates of the receive coil sensitivity profiles. These estimates must be accurate over both the object and its surrounding regions to avoid generating artifacts in the reconstructed images. Regularized estimation methods that involve minimizing a cost function containing both a data-fit term and a regularization term provide robust sensitivity estimates. However, these methods can be computationally expensive when dealing with large problems. In this paper, we propose an iterative algorithm based on variable splitting and the augmented Lagrangian method that estimates the coil sensitivity profile by minimizing a quadratic cost function. Our method, ADMM-Circ, reformulates the finite differencing matrix in the regularization term to enable exact alternating minimization steps. We also present a faster variant of this algorithm using intermediate updating of the associated Lagrange multipliers. Numerical experiments with simulated and real data sets indicate that our proposed method converges approximately twice as fast as the preconditioned conjugate gradient method over the entire field-of-view. These concepts may accelerate other quadratic optimization problems.\",\n \"Title: Accelerated Edge-Preserving Image Restoration Without Boundary Artifacts\\nYear: 2013\\n\\nAbstract: To reduce blur in noisy images, regularized image restoration methods have been proposed that use nonquadratic regularizers (like $l_{1}$ regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a noncirculant model could prevent these artifacts at the cost of increased computational complexity. In this paper, we propose to use a circulant blur model combined with a masking operator that prevents wraparound artifacts. The resulting model is noncirculant, so we propose an efficient algorithm using variable splitting and augmented Lagrangian (AL) strategies. Our variable splitting scheme, when combined with the AL framework and alternating minimization, leads to simple linear systems that can be solved noniteratively using fast Fourier transforms (FFTs), eliminating the need for more expensive conjugate gradient-type solvers. The proposed method can also efficiently tackle a variety of convex regularizers, including edge-preserving (e.g., total-variation) and sparsity promoting (e.g., $l_{1}$-norm) regularizers. Simulation results show fast convergence of the proposed method, along with improved image quality at the boundaries where the circulant model is inaccurate.\",\n \"Title: Iterative tomographic image reconstruction using Fourier-based forward and back-projectors.\\nYear: 2004\\n\\nAbstract: Iterative image reconstruction algorithms play an increasingly important role in modern tomographic systems, especially in emission tomography. With the fast increase of the sizes of the tomographic data, reduction of the computation demands of the reconstruction algorithms is of great importance. Fourier-based forward and back-projection methods have the potential to considerably reduce the computation time in iterative reconstruction. Additional substantial speed-up of those approaches can be obtained utilizing powerful and cheap off-the-shelf fast Fourier transform (FFT) processing hardware. The Fourier reconstruction approaches are based on the relationship between the Fourier transform of the image and Fourier transformation of the parallel-ray projections. The critical two steps are the estimations of the samples of the projection transform, on the central section through the origin of Fourier space, from the samples of the transform of the image, and vice versa for back-projection. Interpolation errors are a limitation of Fourier-based reconstruction methods. We have applied min-max optimized Kaiser-Bessel interpolation within the nonuniform FFT (NUFFT) framework and devised ways of incorporation of resolution models into the Fourier-based iterative approaches. Numerical and computer simulation results show that the min-max NUFFT approach provides substantially lower approximation errors in tomographic forward and back-projection than conventional interpolation methods. Our studies have further confirmed that Fourier-based projectors using the NUFFT approach provide accurate approximations to their space-based counterparts but with about ten times faster computation, and that they are viable candidates for fast iterative image reconstruction.\",\n \"Title: Accelerated Monotonic Algorithms for Transmission Tomography\\nYear: 1998\\n\\nAbstract: We present a framework for designing fast and mono- tonic algorithms for transmission tomography penalized- likelihood image reconstruction. The new algorithms are based on paraboloidal surrogate functions for the log- likelihood. Due to the form of the log-likelihood func- tion, it is possible to find low curvature surrogate func- tions that guarantee monotonicity. Unlike previous meth- ods, the proposed surrogate functions lead to monotonic al- gorithms even for the nonconvex log- likelihood that arises due to background events such as scatter and random coin- cidences. The gradient and the curvature of the likelihood terms are evaluated only once per iteration. Since the prob- lem is simplified, the CPU time per iteration is less than that of current algorithms which directly minimize the ob- jective, yet the convergence rate is comparable. The sim- plicity, monotonicity and speed of the new algorithms are quite attractive. The convergence rates of the algorithms are demonstrated using real PET transmission scans. incidences in PET and emission crosstalk in SPECT. The assumption of no background counts can only be valid in X-ray CT. In this paper, we present an algorithm which is guaranteed to be monotonic even in the non-convex objec- tive function case. This algorithm depends on paraboloidal surrogate functions to the log-likelihood which transform the problem into a simpler optimization problem at each iteration. To obtain the paraboloid, we find 1-D parabolic functions that are tangent to and lie above each of the terms in the log-likelihood, similar to Huber's method for robust linear regression (3).\",\n \"Title: Separate magnitude and phase regularization via compressed sensing.\\nYear: 2012\\n\\nAbstract: Compressed sensing (CS) has been used for accelerating magnetic resonance imaging acquisitions, but its use in applications with rapid spatial phase variations is challenging, e.g., proton resonance frequency shift (PRF-shift) thermometry and velocity mapping. Previously, an iterative MRI reconstruction with separate magnitude and phase regularization was proposed for applications where magnitude and phase maps are both of interest, but it requires fully sampled data and unwrapped phase maps. In this paper, CS is combined into this framework to reconstruct magnitude and phase images accurately from undersampled data. Moreover, new phase regularization terms are proposed to accommodate phase wrapping and to reconstruct images with encoded phase variations, e.g., PRF-shift thermometry and velocity mapping. The proposed method is demonstrated with simulated thermometry data and in vivo velocity mapping data and compared to conventional phase corrected CS.\",\n \"Title: Parallel MR image reconstruction using augmented Lagrangian methods.\\nYear: 2011\\n\\nAbstract: Magnetic resonance image (MRI) reconstruction using SENSitivity Encoding (SENSE) requires regularization to suppress noise and aliasing effects. Edge-preserving and sparsity-based regularization criteria can improve image quality, but they demand computation-intensive nonlinear optimization. In this paper, we present novel methods for regularized MRI reconstruction from undersampled sensitivity en...\",\n \"Title: A penalized-likelihood image reconstruction method for emission tomography, compared to postsmoothed maximum-likelihood with matched spatial resolution.\\nYear: 2003\\n\\nAbstract: Regularization is desirable for image reconstruction in emission tomography. A powerful regularization method is the penalized-likelihood (PL) reconstruction algorithm (or equivalently, maximum a posteriori reconstruction), where the sum of the likelihood and a noise suppressing penalty term (or Bayesian prior) is optimized. Usually, this approach yields position-dependent resolution and bias. However, for some applications in emission tomography, a shift-invariant point spread function would be advantageous. Recently, a new method has been proposed, in which the penalty term is tuned in every pixel to impose a uniform local impulse response. In this paper, an alternative way to tune the penalty term is presented. We performed positron emission tomography and single photon emission computed tomography simulations to compare the performance of the new method to that of the postsmoothed maximum-likelihood (ML) approach, using the impulse response of the former method as the postsmoothing filter for the latter. For this experiment, the noise properties of the PL algorithm were not superior to those of postsmoothed ML reconstruction.\",\n \"Title: Spatially-Variant Roughness Penalty Design for Uniform Resolution in Penalized-Likelihood Image Reconstruction\\nYear: 1998\\n\\nAbstract: Traditional space-invariant regularization schemes in tomographic image reconstruction using penalized- likelihood estimators produce images with nonuniform resolution properties. The local point spread functions that quantify the local smoothing properties of such estimators are not only space-variant and asymmetric, but are also object-dependent even for space-invariant systems. We propose a new regularization scheme for increased spatial uniformity and demonstrate the resolution properties of this new method versus conventional regularization schemes through an investigation of local point spread functions.\",\n \"Title: Relaxed ordered subsets algorithm for image restoration of confocal microscopy\\nYear: 2002\\n\\nAbstract: The expectation-maximization (EM) algorithm for maximum-likelihood image recovery converges very slowly. Thus, the ordered subsets EM (OS-EM) algorithm has been widely used in image reconstruction for tomography due to an order-of-magnitude acceleration over the EM algorithm. However, OS-EM is not guaranteed to converge. The recently proposed ordered subsets, separable paraboloidal surrogates (OS-SPS) algorithm with relaxation has been shown to converge to the optimal point while providing fast convergence. In this paper, we develop a relaxed OS-SPS algorithm for image restoration. Because data acquisition is different in image restoration than in tomography, we adapt a different strategy for choosing subsets in image restoration which uses pixel location rather than projection angles. Simulation results show that the order-of-magnitude acceleration of the relaxed OS-SPS algorithm can be achieved in restoration. Thus the speed and the guarantee of the convergence of the OS algorithm is advantageous for image restoration as well.\",\n \"Title: TWO STATE MARKOV MODELLING AND DETECTION OF SINGLE ELECTRON SPIN SIGNALS\\nYear: 2004\\n\\nAbstract: The focus of this paper is the optimal detection of piecewise constant binary valued continuous-time (C-T) signals with Markovian state transitions. One example is the classic ran- dom telegraph signal for which the number of states is two and the transitions follow a Poisson process. This signal de- tection problem arises in many different areas of engineer- ing and science, notably modulation classification in digital communications and detection of digital content in continu- ous signals or images with high noise contamination. Our motivation is single electron-spin detection in Magnetic Res- onance Force Microscopy (MRFM), which is an emerging molecular scale imaging modality. We will obtain an optimal discrete time iterative detection algorithm and an associated upper bound on the Receiver Operating Characteristic (ROC) curve. These results will be used to show that the optimal detector reduces to a simple filtered energy detector when the state transition probabilities are symmetric, the signal- to-noise ratio (SNR) is low, and the time-bandwidth product is high. In the general case when the state transition proba- bilities can be either symmetric or asymmetric, the optimal detector reduces to a hybrid filtered energy/amplitude/energy detector when the SNR is low and there are a large number of samples per observation.\",\n \"Title: Forward-Projection Architecture for Fast Iterative Image Reconstruction in X-Ray CT\\nYear: 2012\\n\\nAbstract: Iterative image reconstruction can dramatically improve the image quality in X-ray computed tomography (CT), but the computation involves iterative steps of 3D forward- and back-projection, which impedes routine clinical use. To accelerate forward-projection, we analyze the CT geometry to identify the intrinsic parallelism and data access sequence for a highly parallel hardware architecture. To improve the efficiency of this architecture, we propose a water-filling buffer to remove pipeline stalls, and an out-of-order sectored processing to reduce the off-chip memory access by up to three orders of magnitude. We make a floating-point to fixed-point conversion based on numerical simulations and demonstrate comparable image quality at a much lower implementation cost. As a proof of concept, a 5-stage fully pipelined, 55-way parallel separable-footprint forward-projector is prototyped on a Xilinx Virtex-5 FPGA for a throughput of 925.8 million voxel projections/s at 200 MHz clock frequency, 4.6 times higher than an optimized 16-threaded program running on an 8-core 2.8-GHz CPU. A similar architecture can be applied to back-projection for a complete iterative image reconstruction system. The proposed algorithm and architecture can also be applied to hardware platforms such as graphics processing unit and digital signal processor to achieve significant accelerations.\",\n \"Title: Efficient calculation of resolution and covariance for penalized-likelihood reconstruction in fully 3-D SPECT\\nYear: 2004\\n\\nAbstract: Resolution and covariance predictors have been derived previously for penalized-likelihood estimators. These predictors can provide accurate approximations to the local resolution properties and covariance functions for tomographic systems given a good estimate of the mean measurements. Although these predictors may be evaluated iteratively, circulant approximations are often made for practical co...\",\n \"Title: Fast, Iterative Image Reconstruction for MRI in the Presence of Field Inhomogeneities.\\nYear: 2003\\n\\nAbstract: In magnetic resonance imaging, magnetic field inhomogeneities cause distortions in images that are reconstructed by conventional fast Fourier transform (FFT) methods. Several noniterative image reconstruction methods are used currently to compensate for field inhomogeneities, but these methods assume that the field map that characterizes the off-resonance frequencies is spatially smooth. Recently,...\",\n \"Title: Motion Correction in fMRI by Mapping Slice-to-Volume with Concurrent Field-Inhomogeneity Correction\\nYear: 2004\\n\\nAbstract: Head motion is the major source of error in measuring intensity changes related to given stimuli in fMRI. The effects of head motion are image shifts and field inhomogeneity variations which cause local changes in geometric distortions. The previously developed motion correction method, mapping slice-to-volume (MSV), retrospectively remaps slices that are shifted by head motion to their spatially correct locations in an anatomical reference. Images exhibiting spatially varying geometric distortions require non-linear mapping solutions. An accurate field map can be used for the correction of such spatial distortions. However, field-map changes with head motion and, in practice, only one field-map is available typically. This work evaluates the improved motion correction capability of MSV with concurrent iterative field-corrected reconstruction using only an initial field-map. The results from simulated motion data show effective convergence and accuracy in image registration for the correction of image artifacts complicated by the motion induced field effects.\",\n \"Title: Space-alternating generalized expectation-maximization algorithm\\nYear: 1994\\n\\nAbstract: The expectation-maximization (EM) method can facilitate maximizing likelihood functions that arise in statistical estimation problems. In the classical EM paradigm, one iteratively maximizes the conditional log-likelihood of a single unobservable complete data space, rather than maximizing the intractable likelihood function for the measured or incomplete data. EM algorithms update all parameters simultaneously, which has two drawbacks: 1) slow convergence, and 2) difficult maximization steps due to coupling when smoothness penalties are used. The paper describes the space-alternating generalized EM (SAGE) method, which updates the parameters sequentially by alternating between several small hidden-data spaces defined by the algorithm designer. The authors prove that the sequence of estimates monotonically increases the penalized-likelihood objective, derive asymptotic convergence rates, and provide sufficient conditions for monotone convergence in norm. Two signal processing applications illustrate the method: estimation of superimposed signals in Gaussian noise, and image reconstruction from Poisson measurements. In both applications, the SAGE algorithms easily accommodate smoothness penalties and converge faster than the EM algorithms\",\n \"Title: Nonparametric fixed-interval smoothing with vector splines\\nYear: 1991\\n\\nAbstract: A computationally efficient algorithm for nonparametric smoothing of vector signals with general measurement covariances is presented. This algorithm provides an alternative to the optimal smoothing algorithms that hinge on (possibly inaccurate) parametric state-space models. Automatic procedures that use the measurements to determine how much to smooth are developed and compared. This adaptation allows the data to speak for itself without imposing a Gauss-Markov model structure. A nonparametric approach to covariance estimation for the case of independently identically distributed (i.i.d.) measurement errors is presented. Monte Carlo simulations demonstrate the performance of the algorithm\",\n \"Title: Maximum-likelihood dual-energy tomographic image reconstruction\\nYear: 2002\\n\\nAbstract: Dual-energy (DE) X-ray computed tomography (CT) has shown promise for material characterization and for providing quantitatively accurate CT values in a variety of applications. However, DE-CT has not been used routinely in medicine to date, primarily due to dose considerations. Most methods for DE-CT have used the filtered backprojection method for image reconstruction, leading to suboptimal noise/dose properties. This paper describes a statistical (maximum-likelihood) method for dual-energy X-ray CT that accommodates a wide variety of potential system configurations and measurement noise models. Regularized methods (such as penalized-likelihood or Bayesian estimation) are straightforward extensions. One version of the algorithm monotonically decreases the negative log-likelihood cost function each iteration. An ordered-subsets variation of the algorithm provides a fast and practical version.\",\n \"Title: Model-based estimation techniques for 3-D reconstruction from projections\\nYear: 1988\\n\\nAbstract: A parametric estimation approach to reconstruction from projections with incomplete and very noisy data is described. Embedding prior knowledge about “objects” in the probed domain and about the data acquisition process into stochastic dynamic models, we transform the reconstruction problem into a computationally challenging nonlinear state-estimation problem, where the objects' parametrized descriptions are to be directly estimated from the projection data. This paper is a review in a common framework and a comparative study of two distinct algorithms which were developed recently for the solution of this problem. The first, is an approximate, globally optimal minimum-meansquare-error recursive algorithm. The second is a hierarchical suboptimal Bayesian algorithm. Simulation examples demonstrate accurate reconstructions with as few as four views in a 135° sector, at an average signal to noise ratio of 0.6.\",\n \"Title: Regularized image reconstruction algorithms for dual-isotope myocardial perfusion SPECT (MPS) imaging using a cross-tracer prior.\\nYear: 2011\\n\\nAbstract: In simultaneous dual-isotope myocardial perfusion SPECT (MPS) imaging, data are simultaneously acquired to determine the distributions of two radioactive isotopes. The goal of this work was to develop penalized maximum likelihood (PML) algorithms for a novel cross-tracer prior that exploits the fact that the two images reconstructed from simultaneous dual-isotope MPS projection data are perfectly registered in space. We first formulated the simultaneous dual-isotope MPS reconstruction problem as a joint estimation problem. A cross-tracer prior that couples voxel values on both images was then proposed. We developed an iterative algorithm to reconstruct the MPS images that converges to the maximum a posteriori solution for this prior based on separable surrogate functions. To accelerate the convergence, we developed a fast algorithm for the cross-tracer prior based on the complete data OS-EM (COSEM) framework. The proposed algorithm was compared qualitatively and quantitatively to a single-tracer version of the prior that did not include the cross-tracer term. Quantitative evaluations included comparisons of mean and standard deviation images as well as assessment of image fidelity using the mean square error. We also evaluated the cross tracer prior using a three-class observer study with respect to the three-class MPS diagnostic task, i.e., classifying patients as having either no defect, reversible defect, or fixed defects. For this study, a comparison with conventional ordered subsets-expectation maximization (OS-EM) reconstruction with postfiltering was performed. The comparisons to the single-tracer prior demonstrated similar resolution for areas of the image with large intensity changes and reduced noise in uniform regions. The cross-tracer prior was also superior to the single-tracer version in terms of restoring image fidelity. Results of the three-class observer study showed that the proposed cross-tracer prior and the convergent algorithms improved the image quality of dual-isotope MPS images compared to OS-EM.\",\n \"Title: Tomographic Reconstruction Using Information-Weighted Spline Smoothing\\nYear: 1993\\n\\nAbstract: The conventional method for tomographic image reconstruction, convolution backprojection (CBP), attempts to reduce the effects of measurement noise by radial smoothing with a spatially-invariant filter. Spatially-invariant smoothing is suboptimal when the measurement statistics are nonstationary, and often leads to a choice between oversmoothing or streak artifacts. In this paper, we describe a nonstationary sinogram smoothing method that ac- counts for the relative variances between different detector measurements and for the finite width of tomographic detectors. The method is based on an information-weighted smoothing spline, where the weights are determined from the calibration factors and from the measurements themselves. This weighting diminishes the influence of high variance measurements, such as detectors with relatively poor efficiency, which is shown to reduce streak artifacts. Simulations of emission and transmission tomography applications demonstrate qualitatively improved image noise structure and quantitative improvements in the tradeoffs between bias and variance.\",\n \"Title: Quadratic regularization design for fan beam transmission tomography\\nYear: 2005\\n\\nAbstract: Statistical methods for tomographic image reconstruction have shown considerable potential for improving image quality in X-ray CT. Penalized-likelihood (PL) image reconstruction methods require maximizing an objective function that is based on the log-likelihood of the sinogram measurements and on a roughness penalty I unction to control noise. In transmission tomography, PL methods (and MAP methods) based on conventional quadratic regularization functions lead to nonuniform and anisotropic spatial resolution, even for idealized shift-invariant imaging systems. We have previously addressed this problem for parallel-beam emission tomography by designing data-dependent, shift-variant regularizers that improve resolution uniformity. This paper extends those methods to the fan-beam geometry used in X-ray CT imaging Simulation results demonstrate that the new method for regularization design requires very modest computation and leads to nearly uniform and isotropic spatial resolution in the fan-beam geometry when using quadratic regularization.\",\n \"Title: Regularized methods for topology-preserving smooth nonrigid image registration using B-spline basis\\nYear: 2008\\n\\nAbstract: B-splines are a convenient tool for nonrigid registration, but ensuring invertibility can be challenge. This paper describes a new penalty method that is devised to enforce a sufficient condition for local invertibility and smoothness of nth order B-spline based deformations. Traditional direct Jacobian penalty methods penalize negative Jacobian determinant values only at grid points. In contrast, our new penalty method enforces the sufficient condition for invertibility directly on the B-spline coefficients by using a modified quadratic penalty function so that it enforces invertibility globally over a 3D continuous domain. This approach also saves computation time and memory compared to using Jacobian determinant values. We apply this method to 3D CT images of a thorax at inhale and exhale.\",\n \"Title: Fast Predictions of Variance Images for Fan-Beam Transmission Tomography With Quadratic Regularization.\\nYear: 2007\\n\\nAbstract: Accurate predictions of image variances can be useful for reconstruction algorithm analysis and for the design of regularization methods. Computing the predicted variance at every pixel using matrix-based approximations [1] is impractical. Even most recently adopted methods that are based on local discrete Fourier approximations are impractical since they would require a forward and backprojection and two fast Fourier transform (FFT) calculations for every pixel, particularly for shift-variant systems like fan-beam tomography. This paper describes new \\\"analytical\\\" approaches to predicting the approximate variance maps of 2-D images that are reconstructed by penalized-likelihood estimation with quadratic regularization in fan-beam geometries. The simplest of the proposed analytical approaches requires computation equivalent to one backprojection and some summations, so it is computationally practical even for the data sizes in X-ray computed tomography (CT). Simulation results show that it gives accurate predictions of the variance maps. The parallel-beam geometry is a simple special case of the fan-beam analysis. The analysis is also applicable to 2-D positron emission tomography (PET).\",\n \"Title: Convergent incremental optimization transfer algorithms: application to tomography.\\nYear: 2006\\n\\nAbstract: No convergent ordered subsets (OS) type image reconstruction algorithms for transmission tomography have been proposed to date. In contrast, in emission tomography, there are two known families of convergent OS algorithms: methods that use relaxation parameters, and methods based on the incremental expectation-maximization (EM) approach. This paper generalizes the incremental EM approach by introducing a general framework, \\\"incremental optimization transfer.\\\" The proposed algorithms accelerate convergence speeds and ensure global convergence without requiring relaxation parameters. The general optimization transfer framework allows the use of a very broad family of surrogate functions, enabling the development of new algorithms. This paper provides the first convergent OS-type algorithm for (nonconcave) penalized-likelihood (PL) transmission image reconstruction by using separable paraboloidal surrogates (SPS) which yield closed-form maximization steps. We found it is very effective to achieve fast convergence rates by starting with an OS algorithm with a large number of subsets and switching to the new \\\"transmission incremental optimization transfer (TRIOT)\\\" algorithm. Results show that TRIOT is faster in increasing the PL objective than nonincremental ordinary SPS and even OS-SPS yet is convergent.\",\n \"Title: Dynamic Mr Image And Fieldmap Joint Reconstruction Accounting For Through-Plane Fieldmap Gradients\\nYear: 2011\\n\\nAbstract: In susceptibility-weighted MRI, ignoring the magnetic field inhomogeneity can lead to severe reconstruction artifacts. Correcting for the effects of magnetic field inhomogeneity requires accurate fieldmaps. Especially in functional MRI, dynamic updates are desirable, since the fieldmap may change in time. Also, susceptibility effects that induce field inhomogeneity often have non-zero through-plane gradients, which, if uncorrected, can cause signal loss in the reconstructed images. Most image reconstruction methods that compensate for field inhomogeneity, even using dynamic fieldmap updates, ignore through-plane fieldmap gradients. This work proposes a computationally efficient, model based iterative method for joint reconstruction of image and dynamic fieldmap that accounts for the through-plane gradients of the field inhomogeneity. The proposed method allows for efficient reconstruction by applying fast approximations that allow the use of the conjugate gradient algorithm along with FFTs.\",\n \"Title: Reducing between scanner differences in multi-center PET studies.\\nYear: 2009\\n\\nAbstract: This work is part of the multi-center Alzheimer's Disease Neuroimaging Initiative (ADNI), a large multi-site study of dementia, including patients having mild cognitive impairment (MCI), probable Alzheimer's disease (AD), as well as healthy elderly controls. A major portion of ADNI involves the use of [18F]-fluorodeoxyglucose (FDG) with positron emission tomography (PET). The objective of this paper is the reduction of inter-scanner differences in the FDG-PET scans obtained from the 50 participating PET centers having fifteen different scanner models. In spite of a standardized imaging protocol, systematic inter-scanner variability in PET images from various sites is observed primarily due to differences in scanner resolution, reconstruction techniques, and different implementations of scatter and attenuation corrections. Two correction steps were developed by comparison of 3-D Hoffman brain phantom scans with the ‘gold standard’ digital 3-D Hoffman brain phantom: i) high frequency correction; where a smoothing kernel for each scanner model was estimated to smooth all images to a common resolution and ii) low frequency correction; where smooth affine correction factors were obtained to reduce the attenuation and scatter correction errors. For the phantom data, the high frequency correction reduced the variability by 20%–50% and the low frequency correction further reduced the differences by another 20%–25%. Correction factors obtained from phantom studies were applied to 95 scans from normal control subjects obtained from the participating sites. The high frequency correction reduced differences similar to the phantom studies. However, the low frequency correction did not further reduce differences; hence further refinement of the procedure is necessary.\",\n \"Title: Emission image reconstruction for randoms-precorrected PET allowing negative sinogram values.\\nYear: 2004\\n\\nAbstract: Most positron emission tomography (PET) emission scans are corrected for accidental coincidence (AC) events by real-time subtraction of delayed-window coincidences, leaving only the randoms-precorrected data available for image reconstruction. The real-time randoms precorrection compensates in mean for AC events but destroys the Poisson statistics. The exact log-likelihood for randoms-precorrected data is inconvenient, so practical approximations are needed for maximum likelihood or penalized-likelihood image reconstruction. Conventional approximations involve setting negative sinogram values to zero, which can induce positive systematic biases, particularly for scans with low counts per ray. We propose new likelihood approximations that allow negative sinogram values without requiring zero-thresholding. With negative sinogram values, the log-likelihood functions can be nonconcave, complicating maximization; nevertheless, we develop monotonic algorithms for the new models by modifying the separable paraboloidal surrogates and the maximum-likelihood expectation-maximization (ML-EM) methods. These algorithms ascend to local maximizers of the objective function. Analysis and simulation results show that the new shifted Poisson (SP) model is nearly free of systematic bias yet keeps low variance. Despite its simpler implementation, the new SP performs comparably to the saddle-point model which has shown the best performance (as to systematic bias and variance) in randoms-precorrected PET emission reconstruction.\",\n \"Title: Regularization Parameter Selection for Nonlinear Iterative Image Restoration and MRI Reconstruction Using GCV and SURE-Based Methods\\nYear: 2012\\n\\nAbstract: Regularized iterative reconstruction algorithms for imaging inverse problems require selection of appropriate regularization parameter values. We focus on the challenging problem of tuning regularization parameters for nonlinear algorithms for the case of additive (possibly complex) Gaussian noise. Generalized cross-validation (GCV) and (weighted) mean-squared error (MSE) approaches [based on Stein's unbiased risk estimate (SURE)] need the Jacobian matrix of the nonlinear reconstruction operator (representative of the iterative algorithm) with respect to the data. We derive the desired Jacobian matrix for two types of nonlinear iterative algorithms: a fast variant of the standard iterative reweighted least-squares method and the contemporary split-Bregman algorithm, both of which can accommodate a wide variety of analysis- and synthesis-type regularizers. The proposed approach iteratively computes two weighted SURE-type measures: predicted-SURE and projected-SURE (which require knowledge of noise variance $\\\\sigma^{2}$), and GCV (which does not need $\\\\sigma^{2}$) for these algorithms. We apply the methods to image restoration and to magnetic resonance image (MRI) reconstruction using total variation and an analysis-type $\\\\ell_{1}$-regularization. We demonstrate through simulations and experiments with real data that minimizing predicted-SURE and projected-SURE consistently lead to near-MSE-optimal reconstructions. We also observe that minimizing GCV yields reconstruction results that are near-MSE-optimal for image restoration and slightly suboptimal for MRI. Theoretical derivations in this paper related to Jacobian matrix evaluations can be extended, in principle, to other types of regularizers and reconstruction algorithms.\",\n \"Title: Grouped-Coordinate Ascent Algorithms for Penalized-Likelihood Transmission Image Reconstruction\\nYear: 1997\\n\\nAbstract: Presents a new class of algorithms for penalized-likelihood reconstruction of attenuation maps from low-count transmission scans. We derive the algorithms by applying to the transmission log-likelihood a version of the convexity technique developed by De Pierro for emission tomography. The new class includes the single-coordinate ascent (SCA) algorithm and Lange's convex algorithm for transmission...\",\n \"Title: Maximum Likelihood Transmission Image Reconstruction for Overlapping Transmission Beams\\nYear: 2000\\n\\nAbstract: In many transmission imaging geometries, the transmitted "beams" of photons overlap on the detector, such that a detector element may record photons that originated in different sources or source locations and thus traversed different paths through the object. Examples include systems based on scanning line sources or on multiple parallel rod sources. The overlap of these beams has been disregarde...\",\n \"Title: Regularized Field Map Estimation in MRI.\\nYear: 2008\\n\\nAbstract: In fast magnetic resonance (MR) imaging with long readout times, such as echo-planar imaging (EPI) and spiral scans, it is important to correct for the effects of field inhomogeneity to reduce image distortion and blurring. Such corrections require an accurate field map, a map of the off-resonance frequency at each voxel. Standard field map estimation methods yield noisy field maps, particularly i...\",\n \"Title: A Simple Regularizer for B-spline Nonrigid Image Registration That Encourages Local Invertibility.\\nYear: 2009\\n\\nAbstract: Non rigid image registration is an important task for many medical imaging applications. In particular, for radiation oncology it is desirable to track respiratory motion for thoracic cancer treatment. B-splines are convenient for modeling nonrigid deformations, but ensuring invertibility can be a challenge. This paper describes sufficient conditions for local invertibility of deformations based on B-spline bases. These sufficient conditions can be used with constrained optimization to enforce local invertibility. We also incorporate these conditions into nonrigid image registration methods based on a simple penalty approach that encourages diffeomorphic deformations. Traditional Jacobian penalty methods penalize negative Jacobian determinant values only at grid points. In contrast, our new method enforces a sufficient condition for invertibility directly on the deformation coefficients to encourage invertibility globally over a 3-D continuous domain. The proposed penalty approach requires substantially less compute time than Jacobian penalties per iteration.\",\n \"Title: Intensity-based image registration using robust correlation coefficients.\\nYear: 2004\\n\\nAbstract: The ordinary sample correlation coefficient is a popular similarity measure for aligning images from the same or similar modalities. However, this measure can be sensitive to the presence of "outlier" objects that appear in one image but not the other, such as surgical instruments, the patient table, etc., which can lead to biased registrations. This paper describes an intensity-based image regist...\",\n \"Title: Fast Large-Tip-Angle Multidimensional and Parallel RF Pulse Design in MRI.\\nYear: 2009\\n\\nAbstract: Large-tip-angle multidimensional radio-frequency (RF) pulse design is a difficult problem, due to the nonlinear response of magnetization to applied RF at large tip-angles. In parallel excitation, multidimensional RF pulse design is further complicated by the possibility for transmit field patterns to change between subjects, requiring pulses to be designed rapidly while a subject lies in the scanner. To accelerate pulse design, we introduce a fast version of the optimal control method for large-tip-angle parallel excitation. The new method is based on a novel approach to analytically linearizing the Bloch equation about a large-tip-angle RF pulse, which results in an approximate linear model for the perturbations created by adding a small-tip-angle pulse to a large-tip-angle pulse. The linear model can be evaluated rapidly using nonuniform fast Fourier transforms, and we apply it iteratively to produce a sequence of pulse updates that improve excitation accuracy. We achieve drastic reductions in design time and memory requirements compared to conventional optimal control, while producing pulses of similar accuracy. The new method can also compensate for nonidealities such as main field inhomogeneties.\",\n \"Title: Joint Estimation Of Respiratory Motion And Activity In 4d Pet Using Ct Side Information\\nYear: 2006\\n\\nAbstract: In previous work, we proposed a Poisson statistical model for gated PET data in which the distribution was parametrized in terms of both image intensity and motion parameters. The motion parameters related the activity image in each gate to that of a base image in some fixed gate. By doing maximum loglikelihood (ML) estimation of all parameters simultaneously, one obtains an estimate of the base gate image that exploits the full set of measured sinogram data. Previously, this joint ML approach was compared, in a highly simplified single-slice setting, to more conventional methods. Performance was measured in terms of the recovery of tracer uptake in a synthetic lung nodule. This paper reports the extension to 3D with much more realistic simulated motion. Furthermore, in addition to pure ML estimation, we consider the use of side information from a breath-hold CT scan to facilitate regularization, while preserving hot lesions of the kind seen in FDG oncology studies.\",\n \"Title: Statistical sinogram restoration in dual-energy CT for PET attenuation correction.\\nYear: 2009\\n\\nAbstract: Dual-energy (DE) X-ray computed tomography (CT) has been found useful in various applications. In medical imaging, one promising application is using low-dose DECT for attenuation correction in positron emission tomography (PET). Existing approaches to sinogram material decomposition ignore noise characteristics and are based on logarithmic transforms, producing noisy component sinogram estimates ...\",\n \"Title: Ordered subsets with momentum for accelerated X-ray CT image reconstruction\\nYear: 2013\\n\\nAbstract: Statistical image reconstruction methods provide improved image quality in low-dose X-ray CT. However, the long computation time of iterative algorithms limits their clinical use. Ordered subsets algorithms based on separable quadratic surrogates (OS-SQS) are attractive as they are simple and amenable for massive parallelization in modern computing architecture, but require many iterations to converge. Here, we further accelerate OS algorithms by using momentum techniques. We use real patient CT scan to illustrate that the proposed algorithms converge rapidly compared to previous OS algorithms.\",\n \"Title: Image registration using robust correlation\\nYear: 2002\\n\\nAbstract: We have investigated an intensity-based image registration technique using a robust correlation coefficient as a similarity measure. The proposed method has an advantage over the ordinary correlation coefficient since it reduces the effect of \\\"outlier\\\" image intensity values. For the application of image registration to radiotherapy or image-guided surgery, there may be outlier samples due to the presence of the objects such as surgical instruments. We have verified the usefulness of the proposed method by simulation and phantom experiment.\",\n \"Title: Correction for Collimator-Detector Response in SPECT Using Point Spread Function Template\\nYear: 2013\\n\\nAbstract: Compensating for the collimator-detector response (CDR) in SPECT is important for accurate quantification. The CDR consists of both a geometric response and a septal penetration and collimator scatter response. The geometric response can be modeled analytically and is often used for modeling the whole CDR if the geometric response dominates. However, for radionuclides that emit medium or high-energy photons such as I-131, the septal penetration and collimator scatter response is significant and its modeling in the CDR correction is important for accurate quantification. There are two main methods for modeling the depth-dependent CDR so as to include both the geometric response and the septal penetration and collimator scatter response. One is to fit a Gaussian plus exponential function that is rotationally invariant to the measured point source response at several source-detector distances. However, a rotationally-invariant exponential function cannot represent the star-shaped septal penetration tails in detail. Another is to perform Monte-Carlo (MC) simulations to generate the depth-dependent point spread functions (PSFs) for all necessary distances. However, MC simulations, which require careful modeling of the SPECT detector components, can be challenging and accurate results may not be available for all of the different SPECT scanners in clinics. In this paper, we propose an alternative approach to CDR modeling. We use a Gaussian function plus a 2-D B-spline PSF template and fit the model to measurements of an I-131 point source at several distances. The proposed PSF-template-based approach is nearly non-parametric, captures the characteristics of the septal penetration tails, and minimizes the difference between the fitted and measured CDR at the distances of interest. The new model is applied to I-131 SPECT reconstructions of experimental phantom measurements, a patient study, and a MC patient simulation study employing the XCAT phantom. The proposed model yi- lds up to a 16.5 and 10.8% higher recovery coefficient compared to the results with the conventional Gaussian model and the Gaussian plus exponential model, respectively.\",\n \"Title: Fast Interpolation Operations in Non-Rigid Image Registration\\nYear: 2005\\n\\nAbstract: Much literature on image registration(1-3) has worked with purely geometric image deformation models. For such models, interpolation/resampling operations are often the computationally intensive steps when iteratively minimizing the deformation cost function. This article discusses some techniques for efficiently implementing and accelerating these operations. To simplify presentation, we discuss our ideas in the context of 2D imaging. However, the concepts readily generalize to 3D. Our central technique is a table-lookup scheme that makes somewhat liberal use of RAM, but should not strain the resources of modern processors if certain design parameters are appropriately selected. The technique works by pre-interpolating and tabulating the grid values of the reference image onto a finer grid along one of the axes of the image. The lookup table can be rapidly constructed using FFTs. Our results show that this technique reduces iterative computation by an order of magnitude. When a minimization algorithm employing coordinate block alternation is used, one can obtain still faster computation by storing certain intermediate quantities as state variables. We refer to this technique as state variable hold-over. When combined with table-lookup, state variable hold-over reduces CPU time by about a factor two, as compared to table-lookup alone.\",\n \"Title: Incorporating Mri Region Information Into Spect Reconstruction Using Joint Estimation\\nYear: 1995\\n\\nAbstract: Single Photon Emission Computed Tomographic images(SPECT) have relatively poor resolution. In an attemptto improve SPECT image quality, many methodshave been developed for including anatomic information,extracted from higher resolution, structurally correlated MagneticResonance images(MRI), into SPECT reconstructionprocess. These methods provide improved SPECT reconstructionaccuracy if the anatomic information is perfectlycorrelated with the SPECT functional information. Howeverthere...\",\n \"Title: Model-based image reconstruction for dual-energy X-ray CT with fast KVP switching\\nYear: 2009\\n\\nAbstract: The most recent generation of X-ray CT systems can collect dual energy (DE) sinograms by rapidly switching the X-ray tube voltage between two levels for alternate projection views. This reduces motion artifacts in DE imaging, but yields sinograms that may be angularly under-sampled. This paper describes an iterative algorithm for statistical image reconstruction of material component images (e.g., soft tissue and bone) directly from such under-sampled DE data, without resorting to the interpolation operations required by conventional DE reconstruction methods.\",\n \"Title: ALGORITHMS FOR AREA PRESERVING FLOWS.\\nYear: 2011\\n\\nAbstract: We propose efficient and accurate algorithms for computing certain area preserving geometric motions of curves in the plane, such as area preserving motion by curvature. These schemes are based on a new class of diffusion generated motion algorithms using signed distance functions. In particular, they alternate two very simple and fast operations, namely convolution with the Gaussian kernel and construction of the distance function, to generate the desired geometric flow in an unconditionally stable manner. We present applications of these area preserving flows to large scale simulations of coarsening.\",\n \"Title: Sufficient condition for local invertibility of spatio-temporal 4D B-spline deformations\\nYear: 2010\\n\\nAbstract: Recent advances in medical imaging technologies have made 4D image sequences available in clinical routine. As a consequence, image registration techniques are evolving from alignment of pairs of static volumetric images to spatio-temporal registration of dynamic (4D) images. Since the elastic image registration problem is ill-posed, additional prior information or constraints are usually required to regularize the problem. This work proposes to enforce local invertibility (diffeomorphism) of 4D deformations. A novel sufficient condition for local invertibility over continuous space and time is proposed and a practical regularization prior is designed from the theory. The method has been applied to an image registration (motion tracking) of a dynamic 4D CT image sequence. Results show that using proposed regularizer leads to deformations that are more plausible for respiratory motion than the standard approach without additional temporal regularization.\",\n \"Title: Accelerated Ordered-Subsets Algorithm Based On Separable Quadratic Surrogates For Regularized Image Reconstruction In X-Ray Ct\\nYear: 2011\\n\\nAbstract: Iterative algorithms for X-ray CT image reconstruction offer the possibility of reduced dose and/or improved image quality, but require substantial compute time. Reducing the time will likely require algorithms that can be massively parallelized. Ordered subsets (OS) algorithms update all voxels simultaneously and thus are amenable to such parallelization. We present an new monotonic algorithm for regularized image reconstruction that is derived using optimization transfer with separable quadratic surrogates (SQS). The new algorithm accelerates the convergence rate by adapting reduced curvature values for the regularizer that were proposed by Yu et al. [1] for coordinate descent algorithms. We further accelerate the algorithm using ordered subsets. Simulation results show that the proposed OS algorithm converges faster than the traditional OS algorithm for X-ray CT reconstruction from a limited number of projection views.\",\n \"Title: Fast Monotonic Algorithms for Transmission Tomography\\nYear: 1999\\n\\nAbstract: We present a framework for designing fast and monotonic algorithms for transmission tomography penalized- likelihood image reconstruction. The new algorithms are based on paraboloidal surrogate functions for the log likelihood. Due to the form of the log-likelihood function it is possible to find low curvature surrogate functions that guarantee monotonicity. Unlike previous methods, the proposed surrogate functions lead to monotonic algorithms even for the nonconvex log likelihood that arises due to background events, such as scatter and random coincidences. The gradient and the curvature of the likelihood terms are evaluated only once per iteration. Since the problem is simplified at each iteration, the CPU time is less than that of current algorithms which directly minimize the objective, yet the convergence rate is comparable. The simplicity, monotonic- ity, and speed of the new algorithms are quite attractive. The convergence rates of the algorithms are demonstrated using real and simulated PET transmission scans.\",\n \"Title: Spatial resolution and noise properties of regularized motion-compensated image reconstruction\\nYear: 2009\\n\\nAbstract: Reducing motion artifacts is an important problem in medical image reconstruction. Using gating to partition data into separate frames can reduce motion artifacts but can increase noise in images reconstructed fromindividual frames. One can pool the frames to reduce noise by using motion-compensated image reconstruction (MCIR) methods. MCIR methods have been studied in many medical imaging modalities to reduce both noise and motion artifacts. However, there has been less analysis of the spatial resolution and noise properties of MCIR methods. This paper analyzes the spatial resolution and noise properties of MCIR methods based on a general parametric motion model. For simplicity we consider the motion to be given. We present a method to choose quadratic spatial regularization parameters to provide predictable resolution properties that are independent of the object and the motion. The noise analysis shows that the estimator variance depends on both the measurement covariance and the Jacobian determinant values of the motion. A 2D PET simulation demonstrates the theoretical results.\",\n \"Title: Iterative image reconstruction for dual-energy X-ray CT using regularized material sinogram estimates.\\nYear: 2011\\n\\nAbstract: X-ray CT images have various applications, including CT-based attenuation correction (CTAC) for PET. Low-dose CT imaging is particularly desirable for CTAC. Dual-energy (DE) CT imaging methods may improve the accuracy of attenuation correction in PET. However, conventional DE CT approaches to sinogram material decomposition use logarithmic transforms that are sensitive to noise in low-dose scans. This paper describes a DE reconstruction method based on statistical models that avoids using a logarithm. We first estimate material sinograms directly from the raw DE data (without any logarithm), with mild regularization to control noise and avoid outliers. We then apply a penalized weighted least squares (PWLS) method to reconstruct images of the two material components. We also propose a joint edge-preserving regularizer that uses the prior knowledge that the two material images have many region edges located in the same positions. Preliminary simulation results suggest that this iterative method improves image quality compared to conventional approaches based on log data for low-dose DE CT scans.\",\n \"Title: Motion Robust Magnetic Susceptibility and Field Inhomogeneity Estimation Using Regularized Image Restoration Techniques for fMRI\\nYear: 2008\\n\\nAbstract: In functional MRI, head motion may cause dynamic nonlinear field-inhomogeneity changes, especially with large out-of-plane rotations. This may lead to dynamic geometric distortion or blurring in the time series, which may reduce activation detection accuracy. The use of image registration to estimate dynamic field inhomogeneity maps from a static field map is not sufficient in the presence of such rotations. This paper introduces a retrospective approach to estimate magnetic susceptibility induced field maps of an object in motion, given a static susceptibility induced field map and the associated object motion parameters. It estimates a susceptibility map from a static field map using regularized image restoration techniques, and applies rigid body motion to the former. The dynamic field map is then computed using susceptibility voxel convolution. The method addresses field map changes due to out-of-plane rotations during time series acquisition and does not involve real time field map acquisitions.\",\n \"Title: Analysis Of Unknown-Location Signal Detectability For Regularized Tomographic Image Reconstruction\\nYear: 2006\\n\\nAbstract: Our goal is to optimize regularized image reconstruction methods for emission tomography with respect to the task of detecting small lesions of unknown location in the reconstructed images. We consider model observers whose decisions are based on finding the maximum value of a local test statistic over all possible lesion locations. We use tail probability approximations by Adler (AAP 2000) and Siegmund and Worsley (AS 1995) to evaluate the probabilities of false alarm and detection respectively for the observers of interest. We illustrate how these analytical tools can be used to optimize regularization with respect to the performance (at low probability of false alarm operating points) of a maximum channelized non-prewhitening observer.\",\n \"Title: Fourier-based forward and back-projectors in iterative fan-beam tomographic image reconstruction.\\nYear: 2004\\n\\nAbstract: Fourier-based forward and back-projection methods can reduce computation in iterative tomographic image reconstruction. Recently, an optimized nonuniform fast Fourier transform (NUFFT) approach was shown to yield accurate parallel-beam projections. In this paper, we extend the NUFFT approach to describe an O (N2 log N) projector/backprojector pair for fan-beam transmission tomography. Simulations and experiments with real CT data show that fan-beam Fourier-based forward and back-projection methods can reduce computation for iterative reconstruction while still providing accuracy comparable to their O (N3) space-based counterparts.\",\n \"Title: Statistical Image Reconstruction for Polyenergetic X-ray Computer Tomography\\nYear: 2002\\n\\nAbstract: This paper describes a statistical image reconstruction method for X-ray computed tomography (CT) that is based on a physical model that accounts for the polyenergetic X-ray source spectrum and the measurement nonlinearities caused by energy-dependent attenuation. We assume that the object consists of a given number of nonoverlapping materials, such as soft tissue and bone. The attenuation coeffic...\",\n \"Title: 3D forward and back-projection for X-ray CT using separable footprints.\\nYear: 2010\\n\\nAbstract: Iterative methods for 3D image reconstruction have the potential to improve image quality over conventional filtered back projection (FBP) in X-ray computed tomography (CT). However, the computation burden of 3D cone-beam forward and back-projectors is one of the greatest challenges facing practical adoption of iterative methods for X-ray CT. Moreover, projector accuracy is also important for iterative methods. This paper describes two new separable footprint (SF) projector methods that approximate the voxel footprint functions as 2D separable functions. Because of the separability of these footprint functions, calculating their integrals over a detector cell is greatly simplified and can be implemented efficiently. The SF-TR projector uses trapezoid functions in the transaxial direction and rectangular functions in the axial direction, whereas the SF-TT projector uses trapezoid functions in both directions. Simulations and experiments showed that both SF projector methods are more accurate than the distance-driven (DD) projector, which is a current state-of-the-art method in the field. The SF-TT projector is more accurate than the SF-TR projector for rays associated with large cone angles. The SF-TR projector has similar computation speed with the DD projector and the SF-TT projector is about two times slower.\",\n \"Title: Penalized Likelihood Transmission Image Reconstruction: Unconstrained Monotonic Algorithms\\nYear: 2004\\n\\nAbstract: Statistical reconstruction algorithms in transmission tomography yield improved images relative to the conventional FBP method. The most popular iterative algorithms for this problem are the conjugate gradient (CG) method and ordered subsets (OS) methods. Neither method is ideal. OS methods \\\"converge\\\" quickly, but are suboptimal for problems with factored system matrices. Nonnegativity constraints are not imposed easily by the CG method. To speed convergence, we propose to abandon the nonnegativity constraints (letting the regularization discourage the negative values), and to use quadratic surrogates to choose the step size rather than using an expensive line search. To ensure monotonicity, we develop a modification of the transmission log-likelihood. The resulting algorithm is suitable for large-scale problems with factored system matrices such as X-ray CT image reconstruction with afterglow models. Preliminary results show that the regularization ensures minimal negative values, and that the algorithm is indeed monotone.\",\n \"Title: Model-based estimation with boundary side information or boundary regularization [cardiac emission CT]\\nYear: 1994\\n\\nAbstract: We have previously developed a model-based strategy for joint estimation of myocardial perfusion and boundaries using ECT (Emission Computed Tomography). We have also reported difficulties with boundary estimation in low contrast and low count rate situations. In this paper, we propose using boundary side information (obtainable from high resolution MRI and CT images) or boundary regularization to improve both perfusion and boundary estimation in these situations. To fuse boundary side information into the emission measurements, we formulate a joint log-likelihood function to include auxiliary boundary measurements as well as ECT projection measurements. In addition, we introduce registration parameters to align auxiliary boundary measurements with ECT measurements and jointly estimate these parameters with other parameters of interest from the composite measurements. In simulated PET 0-15 water myocardial perfusion studies using a simplified model, we show that the joint estimation improves perfusion estimation performance and gives boundary alignment accuracy of <0.5 mm even at 0.2 million counts. We implement boundary regularization through formulating a penalized log-likelihood function. We also demonstrate in simulations that simultaneous regularization of the epicardial boundary and myocardial thickness gives comparable perfusion estimation accuracy with the use of boundary side information.\",\n \"Title: Hardware Acceleration Of Iterative Image Reconstruction For X-Ray Computed Tomography\\nYear: 2011\\n\\nAbstract: X-ray computed tomography (CT) images could be improved using iterative image reconstruction if the 3D cone-beam forward-and back-projection computations can be accelerated significantly. We investigated the feasibility of a field-programmable gate array (FPGA) implementation of the separable footprint (SF) forward projector. A 16-bit fixed-point quantization introduces negligible numerical errors without affecting the perceptual image quality. The SF-based 3D cone-beam projector can be efficiently parallelized and its memory bandwidth reduced by exploiting projection geometry and data locality. We demonstrate a fully pipelined, 75-way parallel hardware architecture of the SF forward projector on a Xilinx Virtex-5 FPGA that can complete one forward projection of a 320x320x61 object over 3,625 views in 6.3 seconds.\",\n \"Title: Image recovery using partitioned-separable paraboloidal surrogate coordinate ascent algorithms.\\nYear: 2002\\n\\nAbstract: Iterative coordinate ascent algorithms have been shown to be useful for image recovery, but are poorly suited to parallel computing due to their sequential nature. This paper presents a new fast converging parallelizable algorithm for image recovery that can be applied to a very broad class of objective functions. This method is based on paraboloidal surrogate functions and a concavity technique. The paraboloidal surrogates simplify the optimization problem. The idea of the concavity technique is to partition pixels into subsets that can be updated in parallel to reduce the computation time. For fast convergence, pixels within each subset are updated sequentially using a coordinate ascent algorithm. The proposed algorithm is guaranteed to monotonically increase the objective function and intrinsically accommodates nonnegativity constraints. A global convergence proof is summarized. Simulation results show that the proposed algorithm requires less elapsed time for convergence than iterative coordinate ascent algorithms. With four parallel processors, the proposed algorithm yields a speedup factor of 3.77 relative to single processor coordinate ascent algorithms for a three-dimensional (3-D) confocal image restoration problem.\",\n \"Title: Regularized Estimation Of Stokes-Images From Polarimetric Measurements\\nYear: 2008\\n\\nAbstract: In the remote sensing context the goal of imaging polarimetry is to map the state of polarization of a scene of interest. The polarization state of a scene can be represented by the Stokes parameters. Since the Stokes parameters are not directly measurable one must first make several individual measurements and then the infer the Stokes parameters. We approach the Stokes parameter construction problem using penalized-likelihood estimation. Given the measured linearly polarized images, what is the optimal means by which to deblur and denoise and construct the Stokes parameters? In traditional image restoration one attempts to restore the blurred and noise corrupted data directly. In the case of imaging polarimetry we must answer the question of the optimality of restoring the measured data and then forming the Stokes images or restoring the Stokes images directly. An alternative approach is to estimate the Stokes parameters directly. We define our cost function for reconstruction by a weighted least squares data fit penalty and a regularization penalty. We show that for quadratic regularization the estimators of Stokes and intensity images can be made equal by appropriate choice of regularization parameters. It is empirically shown that, when using edge preserving regularization, estimating Stokes parameters directly leads to somewhat lower error.\",\n \"Title: A new statistical image reconstruction algorithm for polyenergetic X-ray CT\\nYear: 2009\\n\\nAbstract: This paper presents a new statistical reconstruction algorithm for X-ray CT. The algorithm is based on Poisson statistics and a physical model that accounts for the measurement nonlinearities caused by energy-dependent attenuation. We model each voxel's attenuation as a mixture of bone and soft tissue by defining density-dependent tissue fractions, maintaining one unknown per voxel avoiding the need of a pre-segmentation. Rather than requiring the entire X-ray spectrum, the method approximates the 2D beam hardening function corresponding to bone and soft tissue with the 1D function corresponding to water and one or two empirical tuning parameters. Results on simulated human data (NCAT phantom) showed a beam hardening reduction similar to conventional post-processing techniques, but with an improved signal to noise ratio.\",\n \"Title: Spatial Resolution Properties of Motion-Compensated Tomographic Image Reconstruction Methods.\\nYear: 2012\\n\\nAbstract: Many motion-compensated image reconstruction (MCIR) methods have been proposed to correct for subject motion in medical imaging. MCIR methods incorporate motion models to improve image quality by reducing motion artifacts and noise. This paper analyzes the spatial resolution properties of MCIR methods and shows that nonrigid local motion can lead to nonuniform and anisotropic spatial resolution fo...\",\n \"Title: Nonrigid Registration Using Regularization that Accommodates Local Tissue Rigidity\\nYear: 2006\\n\\nAbstract: Regularized nonrigid medical image registration algorithms usually estimate the deformation by minimizing a cost function, consisting of a similarity measure and a penalty term that discourages \\\"unreasonable\\\" deformations. Conventional regularization methods enforce homogeneous smoothness properties of the deformation field; less work has been done to incorporate tissue-type-specific elasticity information. Yet ignoring the elasticity differences between tissue types can result in non-physical results, such as bone warping. Bone structures should move rigidly (locally), unlike the more elastic deformation of soft issues. Existing solutions for this problem either treat different regions of an image independently, which requires precise segmentation and incurs boundary issues; or use an empirical spatial varying \\\"filter\\\" to \\\"correct\\\" the deformation field, which requires the knowledge of a stiffness map and departs from the cost-function formulation. We propose a new approach to incorporate tissue rigidity information into the nonrigid registration problem, by developing a space variant regularization function that encourages the local Jacobian of the deformation to be a nearly orthogonal matrix in rigid image regions, while allowing more elastic deformations elsewhere. For the case of X-ray CT data, we use a simple monotonic increasing function of the CT numbers (in HU) as a \\\"rigidity index\\\" since bones typically have the highest CT numbers. Unlike segmentation-based methods, this approach is flexible enough to account for partial volume effects. Results using a B-spline deformation parameterization illustrate that the proposed approach improves registration accuracy in inhale-exhale CT scans with minimal computational penalty.\",\n \"Title: A splitting-based iterative algorithm for accelerated statistical X-ray CT reconstruction.\\nYear: 2012\\n\\nAbstract: Statistical image reconstruction using penalized weighted least-squares (PWLS) criteria can improve image-quality in X-ray computed tomography (CT). However, the huge dynamic range of the statistical weights leads to a highly shift-variant inverse problem making it difficult to precondition and accelerate existing iterative algorithms that attack the statistical model directly. We propose to allev...\",\n \"Title: A convergence proof of the split Bregman method for regularized least-squares problems.\\nYear: 2014\\n\\nAbstract: The split Bregman (SB) method [T. Goldstein and S. Osher, SIAM J. Imaging Sci., 2 (2009), pp. 323-43] is a fast splitting-based algorithm that solves image reconstruction problems with general l1, e.g., total-variation (TV) and compressed sensing (CS), regularizations by introducing a single variable split to decouple the data-fitting term and the regularization term, yielding simple subproblems that are separable (or partially separable) and easy to minimize. Several convergence proofs have been proposed, and these proofs either impose a \\\"full column rank\\\" assumption to the split or assume exact updates in all subproblems. However, these assumptions are impractical in many applications such as the X-ray computed tomography (CT) image reconstructions, where the inner least-squares problem usually cannot be solved efficiently due to the highly shift-variant Hessian. In this paper, we show that when the data-fitting term is quadratic, the SB method is a convergent alternating direction method of multipliers (ADMM), and a straightforward convergence proof with inexact updates is given using [J. Eckstein and D. P. Bertsekas, Mathematical Programming, 55 (1992), pp. 293-318, Theorem 8]. Furthermore, since the SB method is just a special case of an ADMM algorithm, it seems likely that the ADMM algorithm will be faster than the SB method if the augmented Largangian (AL) penalty parameters are selected appropriately. To have a concrete example, we conduct a convergence rate analysis of the ADMM algorithm using two splits for image restoration problems with quadratic data-fitting term and regularization term. According to our analysis, we can show that the two-split ADMM algorithm can be faster than the SB method if the AL penalty parameter of the SB method is suboptimal. Numerical experiments were conducted to verify our analysis.\",\n \"Title: Covariance Of Kinetic Parameter Estimators Based On Time Activity Curve Reconstructions: Preliminary Study On 1d Dynamic Imaging\\nYear: 2004\\n\\nAbstract: We provide approximate expressions for the covariance matrix of kinetic parameter estimators based on time activity curve (TAC) reconstructions when TACs are modeled as a linear combination of temporal basis functions such as B-splines. The approximations are useful tools for assessing and optimizing the basis functions for TACs and the temporal bins for data in terms of computation and efficiency. In this paper we analyze a 1D temporal problem for simplicity, and we consider a scenario where TACs are reconstructed by penalized-likelihood (PL) estimation incorporating temporal regularization, and kinetic parameters are obtained by maximum likelihood (ML) estimation. We derive approximate formulas for the covariance of the kinetic parameter estimators using 1) the mean and variance approximations for PL estimators in (Fessler, 1996) and 2) Cramer-Rao bounds. The approximations apply to list-mode data as well as bin-mode data.\",\n \"Title: Hybrid Poisson/polynomial objective functions for tomographic image reconstruction from transmission scans\\nYear: 1995\\n\\nAbstract: This paper describes rapidly converging algorithms for computing attenuation maps from Poisson transmission measurements using penalized-likelihood objective functions. We demonstrate that an under-relaxed cyclic coordinate-ascent algorithm converges faster than the convex algorithm of Lange (see ibid., vol.4, no.10, p.1430-1438, 1995), which in turn converges faster than the expectation-maximization (EM) algorithm for transmission tomography. To further reduce computation, one could replace the log-likelihood objective with a quadratic approximation. However, we show with simulations and analysis that the quadratic objective function leads to biased estimates for low-count measurements. Therefore we introduce hybrid Poisson/polynomial objective functions that use the exact Poisson log-likelihood for detector measurements with low counts, but use computationally efficient quadratic or cubic approximations for the high-count detector measurements. We demonstrate that the hybrid objective functions reduce computation time without increasing estimation bias\",\n \"Title: Accelerated nonrigid intensity-based image registration using importance sampling.\\nYear: 2009\\n\\nAbstract: Nonrigid image registration methods using intensity-based similarity metrics are becoming increasingly common tools to estimate many types of deformations. Nonrigid warps can be very flexible with a large number of parameters and gradient optimization schemes are widely used to estimate them. However, for large datasets, the computation of the gradient of the similarity metric with respect to thes...\",\n \"Title: Gradient Based Image Registration Using Importance Sampling\\nYear: 2006\\n\\nAbstract: Analytical gradient based non-rigid image registration methods, using intensity based similarity measures (e.g. mutual information), have proven to be capable of accurately handling many types of deformations. While their versatility is largely in part to their high degrees of freedom, the computation of the gradient of the similarity measure with respect to the many warp parameters becomes very time consuming. Recently, a simple stochastic approximation method using a small random subset of image pixels to approximate this gradient has been shown to be effective. We propose to use importance sampling to improve the accuracy and reduce the variance of this approximation by preferentially selecting pixels near image edges. Initial empirical results show that a combination of stochastic approximation methods and importance sampling greatly improves the rate of convergence of the registration process while preserving accuracy.\",\n \"Title: Estimating 3-D respiratory motion from orbiting views by tomographic image registration.\\nYear: 2007\\n\\nAbstract: Respiratory motion remains a significant source of errors in treatment planning for the thorax and upper abdomen. Recently, we proposed a method to estimate two-dimensional (2-D) object motion from a sequence of slowly rotating X-ray projection views, which we called deformation from orbiting views (DOVs). In this method, we model the motion as a time varying deformation of a static prior of the anatomy. We then optimize the parameters of the motion model by maximizing the similarity between the modeled and actual projection views. This paper extends the method to full three-dimensional (3-D) motion and cone-beam projection views. We address several practical issues for using a cone-beam computed tomography (CBCT) scanner that is integrated in a radiotherapy system, such as the effects of Compton scatter and the limited gantry rotation for one breathing cycle. We also present simulation and phantom results to illustrate the performance of this method.\",\n \"Title: Quadratic Regularization Design for 2-D CT.\\nYear: 2009\\n\\nAbstract: Statistical methods for tomographic image reconstruction have improved noise and spatial resolution properties that may improve image quality in X-ray computed tomography (CT). Penalized weighted least squares (PWLS) methods using conventional quadratic regularization lead to nonuniform and anisotropic spatial resolution due to interactions between the weighting, which is necessary for good noise ...\",\n \"Title: Accelerating ordered subsets image reconstruction for X-ray CT using spatially nonuniform optimization transfer.\\nYear: 2013\\n\\nAbstract: Statistical image reconstruction algorithms in X-ray computed tomography (CT) provide improved image quality for reduced dose levels but require substantial computation time. Iterative algorithms that converge in few iterations and that are amenable to massive parallelization are favorable in multiprocessor implementations. The separable quadratic surrogate (SQS) algorithm is desirable as it is simple and updates all voxels simultaneously. However, the standard SQS algorithm requires many iterations to converge. This paper proposes an extension of the SQS algorithm that leads to spatially nonuniform updates. The nonuniform (NU) SQS encourages larger step sizes for the voxels that are expected to change more between the current and the final image, accelerating convergence, while the derivation of NU-SQS guarantees monotonic descent. Ordered subsets (OS) algorithms can also accelerate SQS, provided suitable \\\"subset balance\\\" conditions hold. These conditions can fail in 3-D helical cone-beam CT due to incomplete sampling outside the axial region-of-interest (ROI). This paper proposes a modified OS algorithm that is more stable outside the ROI in helical CT. We use CT scans to demonstrate that the proposed NU-OS-SQS algorithm handles the helical geometry better than the conventional OS methods and \\\"converges\\\" in less than half the time of ordinary OS-SQS.\",\n \"Title: Conjugate phase MRI reconstruction with spatially variant sample density correction.\\nYear: 2005\\n\\nAbstract: A new image reconstruction method to correct for the effects of magnetic field inhomogeneity in non-Cartesian sampled magnetic resonance imaging (MRI) is proposed. The conjugate phase reconstruction method, which corrects for phase accumulation due to applied gradients and magnetic field inhomogeneity, has been commonly used for this case. This can lead to incomplete correction, in part, due to th...\",\n \"Title: Regularization Design For Isotropic Spatial Resolution In Motion-Compensated Image Reconstruction\\nYear: 2011\\n\\nAbstract: Patient motion degrades image quality in medical imaging. Gating can reduce motion artifacts by using part of the acquired data, but can increase noise. Motion-compensated image reconstruction (MCIR) utilizes all collected data with motion information to reduce motion artifacts and noise.Interactions between Poisson log-likelihood and quadratic regularizers lead to nonuniform and anisotropic spatial resolution in the static case. These undesirable problems can become worse in MCIR due to local motion. We previously compensated for local volume changes in MCIR to provide approximately uniform spatial resolution, but achieved isotropic resolution only for the static case.This paper proposes a quadratic spatial regularizer design that achieves nearly uniform and isotropic spatial resolution in MCIR. We consider \\\"analytical approach\\\" to regularization design that was developed for static image reconstruction and extend it to MCIR methods based on a general parametric motion model. Our proposed regularizer can compensate not only for the effects of interactions between the Poisson log-likelihood and the spatial regularizer but also for the effects of nonrigid motion. A 2D PET simulation demonstrates the theoretical results.\",\n \"Title: Simplified Digital Holographic Reconstruction Using Statistical Methods\\nYear: 2004\\n\\nAbstract: For reconstructing a complex object wavefront from digital holograms. we propose a new penalized-likelihood approach based on the measurement statistics and edge-preserving regularization. The log-likelihood is complicated since the measurements are related to the magnitude of the complex beam. We use optimization transfer to derive a new simplified iterative algorithm that monotonically decreases the cost function. Unlike the conventional FFT-based holographic reconstruction method, the new approach uses all of the measured data, and can be applied to holograms with any (known) reference beam pattern. Simulation results demonstrate the potential for improved image quality.\",\n \"Title: Noise Properties of Motion-Compensated Tomographic Image Reconstruction Methods\\nYear: 2013\\n\\nAbstract: Motion-compensated image reconstruction (MCIR) methods incorporate motion models to improve image quality in the presence of motion. MCIR methods differ in terms of how they use motion information and they have been well studied separately. However, there have been less theoretical comparisions of different MCIR methods. This paper compares the theoretical noise properties of three popular MCIR methods assuming known nonrigid motion. We show the relationship among three MCIR methods-motion-compensated temporal regularization (MTR), the parametric motion model (PMM), and post-reconstruction motion correction (PMC)-for penalized weighted least square cases. These analyses show that PMM and MTR are matrix-weighted sums of all registered image frames, while PMC is a scalar-weighted sum. We further investigate the noise properties of MCIR methods with Poisson models and quadratic regularizers by deriving accurate and fast variance prediction formulas using an “analytical approach.” These theoretical noise analyses show that the variances of PMM and MTR are lower than or comparable to the variance of PMC due to the statistical weighting. These analyses also facilitate comparisons of the noise properties of different MCIR methods, including the effects of different quadratic regularizers, the influence of the motion through its Jacobian determinant, and the effect of assuming that total activity is preserved. Two-dimensional positron emission tomography simulations demonstrate the theoretical results.\",\n \"Title: ITERATIVE SORTING FOR 4DCT IMAGES BASED ON INTERNAL ANATOMY MOTION\\nYear: 2007\\n\\nAbstract: Geometric uncertainties caused by respiratory motion complicate radiotherapy treatment planning. Therefore 4D CT imaging is important in characterizing anatomy motion during breathing. Current 4D CT imaging techniques using multislice CT scanners involve multiple scans at several axial positions and retrospective sorting processes. Most sorting methods are based on externally monitored signals recorded by external monitoring instruments, which may not always accurately catch the actual breathing status and may lead to severe discontinuity artifacts in the sorted CT volumes. We propose a method to reconstruct time-resolved CT volumes based on internal motion to avoid the inaccuracies caused by external breathing signals. In our method, we iteratively sort the 4D CT slices using internal motion based breathing indices. In each iteration, respiratory motion is estimated by updating a motion model to best match a deformed reference volume to each moving multi-slice sub-volumes. The breathing indices as well as the reference volumes are refined for each iteration based on the currently estimated respiratory motion. An example is presented to illustrate the feasibility of our 4D CT sorting method without using any external motion monitoring systems.\",\n \"Title: Spoke pulse design in magnetic resonance imaging using greedy minimax algorithm\\nYear: 2013\\n\\nAbstract: Spoke RF pulse design in MRI requires joint optimization of the k-space trajectory and RF pulse weights. This design task is often modelled as a sparse approximation problem with a cost function evaluating the l2 norm of the excitation error, which can be approximately solved using the orthogonal matching pursuit (OMP) algorithm. However, l2 optimization does not strictly regulate a maximum deviation between excitation and desired patterns, and may leave bright or dark spots in the image. In this paper, we model the pulse design problem as a sparse approximation problem with an l∞ norm cost function, and propose a greedy algorithm for solving this new problem. Simulation results demonstrate that our algorithm can produce improved spoke RF pulses (reduced maximum error) compared to l2 optimization.\",\n \"Title: Regularized Parallel Mri Reconstruction Using An Alternating Direction Method Of Multipliers\\nYear: 2011\\n\\nAbstract: Using sparsity-based regularization to improve magnetic resonance image (MRI) reconstruction quality demands computation-intensive nonlinear optimization. In this paper, we develop an iterative algorithm based on the method of multipliers-augmented Lagrangian (AL) formalism-for reconstruction from sensitivity encoded data using sparsity-based regularization. We first convert the unconstrained reconstruction problem into an equivalent constrained optimization task and attack the constrained version in an AL framework using an alternating direction minimization method-this leads to an alternating direction method of multipliers whose intermediate steps are amenable to parallelization. Numerical experiments with in-vivo human brain data illustrate that the proposed algorithm converges faster than both general-purpose optimization algorithms such as nonlinear conjugate gradient (NCG) and state-of-the-art MFISTA.\",\n \"Title: Fast Joint Reconstruction Of Dynamic R-2* And Field Maps In Functional Mri\\nYear: 2008\\n\\nAbstract: Blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) is conventionally done by reconstructing T-2*-weighted images. However, since the images are unitless they are nonquantifiable in terms of important physiological parameters. An alternative approach is to reconstruct R-2* maps which are quantifiable and have comparable BOLD contrast as T-2*-weighted images. However, conventional R-2* mapping involves long readouts and ignores relaxation during readout. Another problem with fMRI imaging is temporal drift/fluctuations in off-resonance. Conventionally, a field map is collected at the start of the fMRI study to correct for off-resonance, ignoring an), temporal changes. Here, we propose a new fast regularized iterative algorithm that Jointly reconstructs R-2* and field maps for all time frames in fMRI data. To accelerate the algorithm we linearize the MR signal model, enabling the use of fast regularized iterative reconstruction methods. The regularizer was designed to account for the different resolution properties of both R-2* and field maps and provide uniform spatial resolution. For fMRI data with the same temporal frame rate as data collected for T-2*-weighted imaging the resulting R-2* maps performed comparably to T-2*-weighted images in activation detection while also correcting for spatially global and local temporal changes in off-resonance.\",\n \"Title: Augmented Lagrangian With Variable Splitting For Faster Non-Cartesian L-1-Spirit Mr Image Reconstruction\\nYear: 2014\\n\\nAbstract: SPIRiT (iterative self-consistent parallel imaging reconstruction), and its sparsity-regularized variant L-1-SPIRiT, are compatible with both Cartesian and non-Cartesian magnetic resonance imaging sampling trajectories. However, the non-Cartesian framework is more expensive computationally, involving a nonuniform Fourier transform with a nontrivial Gram matrix. We propose a novel implementation of the regularized reconstruction problem using variable splitting, alternating minimization of the augmented Lagrangian, and careful preconditioning. Our new method based on the alternating direction method of multipliers converges much faster than existing methods because of the preconditioners' heightened effectiveness. We demonstrate such rapid convergence substantially improves image quality for a fixed computation time. Our framework is a step forward towards rapid non-Cartesian L-1-SPIRiT reconstructions.\",\n \"Title: Regularization Designs for Uniform Spatial Resolution and Noise Properties in Statistical Image Reconstruction for 3-D X-ray CT\\nYear: 2015\\n\\nAbstract: Statistical image reconstruction methods for X-ray computed tomography (CT) provide improved spatial resolution and noise properties over conventional filtered back-projection (FBP) reconstruction, along with other potential advantages such as reduced patient dose and artifacts. Conventional regularized image reconstruction leads to spatially variant spatial resolution and noise characteristics because of interactions between the system models and the regularization. Previous regularization design methods aiming to solve such issues mostly rely on circulant approximations of the Fisher information matrix that are very inaccurate for undersampled geometries like short-scan cone-beam CT. This paper extends the regularization method proposed in [1] to 3-D cone-beam CT by introducing a hypothetical scanning geometry that helps address the sampling properties. The proposed regularization designs were compared with the original method in [1] with both phantom simulation and clinical reconstruction in 3-D axial X-ray CT. The proposed regularization methods yield improved spatial resolution or noise uniformity in statistical image reconstruction for short-scan axial cone-beam CT.\",\n \"Title: Combining ordered subsets and momentum for accelerated X-ray CT image reconstruction.\\nYear: 2015\\n\\nAbstract: Statistical X-ray computed tomography (CT) reconstruction can improve image quality from reduced dose scans, but requires very long computation time. Ordered subsets (OS) methods have been widely used for research in X-ray CT statistical image reconstruction (and are used in clinical PET and SPECT reconstruction). In particular, OS methods based on separable quadratic surrogates (OS-SQS) are massively parallelizable and are well suited to modern computing architectures, but the number of iterations required for convergence should be reduced for better practical use. This paper introduces OS-SQS-momentum algorithms that combine Nesterov's momentum techniques with OS-SQS methods, greatly improving convergence speed in early iterations. If the number of subsets is too large, the OS-SQS-momentum methods can be unstable, so we propose diminishing step sizes that stabilize the method while preserving the very fast convergence behavior. Experiments with simulated and real 3D CT scan data illustrate the performance of the proposed algorithms.\",\n \"Title: Fast X-ray CT image reconstruction using a linearized augmented lagrangian method with ordered subsets.\\nYear: 2015\\n\\nAbstract: Augmented Lagrangian (AL) methods for solving convex optimization problems with linear constraints are attractive for imaging applications with composite cost functions due to the empirical fast convergence rate under weak conditions. However, for problems such as X-ray computed tomography (CT) image reconstruction, where the inner least-squares problem is challenging and requires iterations, AL methods can be slow. This paper focuses on solving regularized (weighted) least-squares problems using a linearized variant of AL methods that replaces the quadratic AL penalty term in the scaled augmented Lagrangian with its separable quadratic surrogate function, leading to a simpler ordered-subsets (OS) accelerable splitting-based algorithm, OS-LALM. To further accelerate the proposed algorithm, we use a second-order recursive system analysis to design a deterministic downward continuation approach that avoids tedious parameter tuning and provides fast convergence. Experimental results show that the proposed algorithm significantly accelerates the convergence of X-ray CT image reconstruction with negligible overhead and can reduce OS artifacts when using many subsets.\",\n \"Title: Fast parallel MR image reconstruction via B1-based, adaptive restart, iterative soft thresholding algorithms (BARISTA).\\nYear: 2015\\n\\nAbstract: Sparsity-promoting regularization is useful for combining compressed sensing assumptions with parallel MRI for reducing scan time while preserving image quality. Variable splitting algorithms are the current state-of-the-art algorithms for SENSE-type MR image reconstruction with sparsity-promoting regularization. These methods are very general and have been observed to work with almost any regularizer; however, the tuning of associated convergence parameters is a commonly-cited hindrance in their adoption. Conversely, majorize-minimize algorithms based on a single Lipschitz constant have been observed to be slow in shift-variant applications such as SENSE-type MR image reconstruction since the associated Lipschitz constants are loose bounds for the shift-variant behavior. This paper bridges the gap between the Lipschitz constant and the shift-variant aspects of SENSE-type MR imaging by introducing majorizing matrices in the range of the regularizer matrix. The proposed majorize-minimize methods (called BARISTA) converge faster than state-of-the-art variable splitting algorithms when combined with momentum acceleration and adaptive momentum restarting. Furthermore, the tuning parameters associated with the proposed methods are unitless convergence tolerances that are easier to choose than the constraint penalty parameters required by variable splitting algorithms.\",\n \"Title: Edge-preserving image denoising via group coordinate descent on the GPU.\\nYear: 2015\\n\\nAbstract: Image denoising is a fundamental operation in image processing, and its applications range from the direct (photographic enhancement) to the technical (as a subproblem in image reconstruction algorithms). In many applications, the number of pixels has continued to grow, while the serial execution speed of computational hardware has begun to stall. New image processing algorithms must exploit the power offered by massively parallel architectures like graphics processing units (GPUs). This paper describes a family of image denoising algorithms well-suited to the GPU. The algorithms iteratively perform a set of independent, parallel 1D pixel-update subproblems. To match GPU memory limitations, they perform these pixel updates in-place and only store the noisy data, denoised image, and problem parameters. The algorithms can handle a wide range of edge-preserving roughness penalties, including differentiable convex penalties and anisotropic total variation. Both algorithms use the majorize-minimize framework to solve the 1D pixel update subproblem. Results from a large 2D image denoising problem and a 3D medical imaging denoising problem demonstrate that the proposed algorithms converge rapidly in terms of both iteration and run-time.\",\n \"Title: Multi-material decomposition using statistical image reconstruction for spectral CT.\\nYear: 2014\\n\\nAbstract: Spectral computed tomography (CT) provides information on material characterization and quantification because of its ability to separate different basis materials. Dual-energy (DE) CT provides two sets of measurements at two different source energies. In principle, two materials can be accurately decomposed from DECT measurements. However, many clinical and industrial applications require three or more material images. For triple-material decomposition, a third constraint, such as volume conservation, mass conservation or both, is required to solve three sets of unknowns from two sets of measurements. The recently proposed flexible image-domain (ID) multi-material decomposition) method assumes each pixel contains at most three materials out of several possible materials and decomposes a mixture pixel by pixel. We propose a penalized-likelihood (PL) method with edge-preserving regularizers for each material to reconstruct multi-material images using a similar constraint from sinogram data. We develop an optimization transfer method with a series of pixel-wise separable quadratic surrogate (PWSQS) functions to monotonically decrease the complicated PL cost function. The PWSQS algorithm separates pixels to allow simultaneous update of all pixels, but keeps the basis materials coupled to allow faster convergence rate than our previous proposed material- and pixel-wise SQS algorithms. Comparing with the ID method using 2-D fan-beam simulations, the PL method greatly reduced noise, streak and cross-talk artifacts in the reconstructed basis component images, and achieved much smaller root mean square errors.\",\n \"Title: Alternating Direction Method of Multiplier for Tomography With Nonlocal Regularizers.\\nYear: 2014\\n\\nAbstract: The ordered subset expectation maximization (OSEM) algorithm approximates the gradient of a likelihood function using a subset of projections instead of using all projections so that fast image reconstruction is possible for emission and transmission tomography such as SPECT, PET, and CT. However, OSEM does not significantly accelerate reconstruction with computationally expensive regularizers such as patch-based nonlocal (NL) regularizers, because the regularizer gradient is evaluated for every subset. We propose to use variable splitting to separate the likelihood term and the regularizer term for penalized emission tomographic image reconstruction problem and to optimize it using the alternating direction method of multiplier (ADMM). We also propose a fast algorithm to optimize the ADMM parameter based on convergence rate analysis. This new scheme enables more sub-iterations related to the likelihood term. We evaluated our ADMM for 3-D SPECT image reconstruction with a patch-based NL regularizer that uses the Fair potential function. Our proposed ADMM improved the speed of convergence substantially compared to other existing methods such as gradient descent, EM, and OSEM using De Pierro's approach, and the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm.\",\n \"Title: Regularized Estimation Of Magnitude And Phase Of Multi-Coil B-1 Field Via Bloch-Siegert B-1 Mapping And Coil Combination Optimizations\\nYear: 2014\\n\\nAbstract: Parallel excitation requires fast and accurate map estimation. Bloch-Siegert (BS) B-1 mapping is very fast and accurate over a large dynamic range. When applied to multi-coil systems, however, this phase-based method may produce low signal-to-noise ratio estimates in low magnitude regions due to localized excitation patterns of parallel excitation systems. Also, the imaging time increases with the number of coils. In this work, we first propose to modify the standard BS B-1 mapping sequence so that it avoids the scans required by previous B-1 phase estimation methods. A regularized method is then proposed to jointly estimate the magnitude and phase of multi-coil B-1 maps from BS mapping data, improving estimation quality by using the prior knowledge of the smoothness of B-1 magnitude and phase. Lastly, we use Cramer-Rao lower bound analysis to optimize the coil combinations, to improve the quality of the raw data for B-1 estimation. The proposed methods are demonstrated by simulations and phantom experiments.\",\n \"Title: Nmr Object Boundaries - B-Spline Modeling And Estimator Performance\\nYear: 1995\\n\\nAbstract: We give estimation error bounds and specify optimal estimators for continuous, closed boundary curves in an NMR image. The boundary is parameterized us- ing periodic B-Splines. A Cramer-Rao lower bound on mean-square-estimate error in the presence of system smoothing and Gaussian noise is derived, and the per- formance of maximum likelihood and penalized maxi- muin likelihood estimators is compared to this bound. Finally, we comment on the usefulness of estimates of the boundary for providing anatomical side information in the reconstruction of functional tomographic images like those of a PET or SPECT system.\",\n \"Title: Regularized estimation of Bloch-Siegert |B1+| maps in MRI\\nYear: 2014\\n\\nAbstract: The Bloch-Siegert (BS) method is a fast method for finding RF transmit fields (|B1+| maps) in MRI based on the phase shift induced by an off-resonance pulse. The phase calculation can be very noisy in regions with low image magnitude, leading to inaccurate estimations using the conventional method. This paper proposes a penalized likelihood (PL) estimator of the |B1+| map in the image domain, and a fast optimization transfer algorithm for solving the problem. We validated our proposed method with both simulation and experimental data sets.\",\n \"Title: Phase Retrieval Of Sparse Signals Using Optimization Transfer And Admm\\nYear: 2014\\n\\nAbstract: We propose a reconstruction method for the phase retrieval problem prevalent in optics, crystallography, and other imaging applications. Our approach uses signal sparsity to provide robust reconstruction, even in the presence of outliers. Our method is multi-layered, involving multiple random initial conditions, convex majorization, variable splitting, and alternating directions method of multipliers (ADMM)-based implementation. Monte Carlo simulations demonstrate that our algorithm can correctly and robustly detect sparse signals from full and undersampled sets of squared-magnitude-only measurements, corrupted by additive noise or outliers.\",\n \"Title: Alternating minimization approach for multi-frame image reconstruction.\\nYear: 2012\\n\\nAbstract: There are a variety of imaging modalities that record a sequence of measurements where the sensor and/or the objects in the scene aremoving and the goal is to reconstruct an image without motion blur. Examples include multi-frame super-resolution problems and motion-compensated image reconstruction problems in medical imaging. Various methods have been proposed for such applications, often in the context of specific imaging modalities. However, many such methods can be formulated in a common framework and thus solved by the same optimization method. To solve the reconstruction problem efficiently, the optimization method must be designed carefully.This paper proposes a novel approach to solve multi-frame image reconstruction problems more efficiently. We use a variable-splitting technique to dissociate the original problem into a few simpler problems that are then solved individually using an alternating minimization method. The proposed method is amenable to preconditioning, parallelization, and application of block iterative algorithms to the sub-problems. Simulation results demonstrate that even with simple diagonal or circulant preconditioners, the proposed method converges faster than the conjugate gradient (CG) method.\",\n \"Title: A Bayesian approach to reconstruction from incomplete projections of a multiple object 3D domain\\nYear: 1989\\n\\nAbstract: An estimation approach is described for three-dimensional reconstruction from line integral projections using incomplete and very noisy data. Generalized cylinders parameterized by stochastic dynamic models are used to represent prior knowledge about the properties of objects of interest in the probed domain. The object models, a statistical measurement model, and the maximum a posteriori probability performance criterion are combined to reformulate the reconstruction problem as a computationally challenging nonlinear estimation problem. For computational feasibility, a suboptimal hierarchical algorithm is described whose individual steps are locally optimal and are combined to satisfy a global optimality criterion. The formulation and algorithm are restricted to objects whose center axis is a single-valued function of a fixed spatial coordinate. Simulation examples demonstrate accurate reconstructions with as few as four views in a 135 degrees sector, at an average signal-to-noise ratio of 3.3.\",\n \"Title: Penalized weighted least-squares image reconstruction for positron emission tomography.\\nYear: 1994\\n\\nAbstract: This paper presents an image reconstruction method for positron-emission tomography (PET) based on a penalized, weighted least- squares (PWLS) objective. For PET measurements that are precorrected for accidental coincidences, we argue statistically that a least-squares ob- jective function is as appropriate, if not more so, than the popular Pois- son likelihood objective. We propose a simple data-based method for determining the weights that accounts for attenuation and detector effi- ciency. A nonnegative successive over-relaxation (+SOR) algorithm con- verges rapidly to the global minimum of the PWLS objective. Quan- titative simulation results demonstrate that the bias/var iance tradeoff of the PWLS+SOR method is comparable to the maximum-likelihood expectation-maximization (ML-EM) method (but with fewer iterations), and is improved relative to the conventional filtered backpr ojection (FBP) method. Qualitative results suggest that the streak artifa cts common to the FBP method are nearly eliminated by the PWLS+SOR method, and indicate that the proposed method for weighting the measurements is a sig- nificant factor in the improvement over FBP.\",\n \"Title: Fast, iterative, field-corrected image reconstruction for MRI\\nYear: 2002\\n\\nAbstract: Magnetic field inhomogeneities cause distortions in the reconstructed images for non-cartesian k-space MRI (using spirals, for example). Several noniterative methods are currently used to compensate for the off-resonance during the reconstruction, but these methods rely on the assumption of a smoothly varying field map. Recently, iterative methods have been proposed that do not rely on this assumption and have the potential to estimate undistorted field maps, but suffer from prohibitively long computation times. In this abstract we present a min-max derived, time-segmented approximation to the signal equation for MRI that, when combined with the nonuniform fast Fourier transform, provides a fast, accurate field-corrected image reconstruction.\",\n \"Title: Segmentation-free statistical image reconstruction for polyenergetic X-ray computed tomography\\nYear: 2002\\n\\nAbstract: This paper describes a statistical iterative reconstruction method for X-ray CT based on a physical model that accounts for the polyenergetic X-ray source spectrum and the measure- ment nonlinearities caused by energy-dependent attenuation. The algorithm accommodates mixtures of tissues with known mass attenuation coefficients but unknown densities. We formulate a penalized-likelihood approach for this polyen- ergetic model based on Poisson statistics.\",\n \"Title: Moments of implicitly defined estimators (e.g. ML and MAP): applications to transmission tomography\\nYear: 1995\\n\\nAbstract: Many estimators in signal processing problems are defined implicitly as the maximum of an objective function, such as maximum likelihood (ML) and maximum a posteriori (MAP) methods. Exact analytical expressions for the mean and variance of such estimators are usually unavailable, so investigators usually resort to numerical simulations. The paper describes approximate analytical expressions for the mean and variance of implicitly defined estimators. The expressions are defined solely in terms of the partial derivatives of whatever objective function one uses for estimation. The authors demonstrate the utility and accuracy of the approximations in a PET transmission computed tomography application with Poisson statistics. The approximations should be useful in a wide range of estimation problems\",\n \"Title: Compensation for nonuniform resolution using penalized-likelihood reconstruction in space-variant imaging systems.\\nYear: 2004\\n\\nAbstract: Imaging systems that form estimates using a statistical approach generally yield images with nonuniform resolution properties. That is, the reconstructed images possess resolution properties marked by space-variant and/or anisotropic responses. We have previously developed a space-variant penalty for penalized-likelihood (PL) reconstruction that yields nearly uniform resolution properties. We demonstrated how to calculate this penalty efficiently and apply it to an idealized positron emission tomography (PET) system whose geometric response is space-invariant. In this paper, we demonstrate the efficient calculation and application of this penalty to space-variant systems. (The method is most appropriate when the system matrix has been precalculated.) We apply the penalty to a large field of view PET system where crystal penetration effects make the geometric response space-variant, and to a two-dimensional single photon emission computed tomography system whose detector responses are modeled by a depth-dependent Gaussian with linearly varying full-width at half-maximum. We perform a simulation study comparing reconstructions using our proposed PL approach with other reconstruction methods and demonstrate the relative resolution uniformity, and discuss tradeoffs among estimators that yield nearly uniform resolution. We observe similar noise performance for the PL and post-smoothed maximum-likelihood (ML) approaches with carefully matched resolution, so choosing one estimator over another should be made on other factors like computational complexity and convergence rates of the iterative reconstruction. Additionally, because the postsmoothed ML and the proposed PL approach can outperform one another in terms of resolution uniformity depending on the desired reconstruction resolution, we present and discuss a hybrid approach adopting both a penalty and post-smoothing.\",\n \"Title: Penalized likelihood emission image reconstruction with uncertain boundary information\\nYear: 1997\\n\\nAbstract: In this paper, a method is introduced for incorporating perfectly registered MRI boundary information into a penalized likelihood emission reconstruction scheme. The boundary curve is modeled as a periodic spline whose coefficients are estimated from the MRI image. The resulting boundary estimate is mapped to a spatially variant set of Gibbs weights. When incorporated into a quadratic roughness penalty, these weights improve emission reconstruction bias/variance performance by preventing smoothing across the estimated boundary. Finally, we derive a new penalty function that accounts for the uncertainty inherent in the boundary estimates\",\n \"Title: Iterative image reconstruction in MRI with separate magnitude and phase regularization\\nYear: 2004\\n\\nAbstract: Iterative methods for image reconstruction in MRI are useful in several applications, including reconstruction from non-Cartesian k-space samples, compensation for magnetic field inhomogeneities, and imaging with multiple receive coils. Existing iterative MR image reconstruction methods are either unregularized, and therefore sensitive to noise, or have used regularization methods that smooth the complex valued image. These existing methods regularize the real and imaginary components of the image equally. In many MRI applications, including T ∗ 2-weighted imaging as used in fMRI BOLD imaging, one expects most of the signal in- formation of interest to be contained in the magnitude of the voxel value, whereas the phase values are expected to vary smoothly spatially. This paper proposes separate regu- larization of the magnitude and phase components, preserv- ing the spatial resolution of the magnitude component while strongly regularizing the phase component. This leads to a non-convex regularized least-squares cost function. We describe a new iterative algorithm that monotonically de- creases this cost function. The resulting images have re- duced noise relative to conventional regularization methods.\",\n \"Title: Edge-preserving tomographic reconstruction with nonlocal regularization.\\nYear: 2002\\n\\nAbstract: Tomographic image reconstruction using statistical methods can provide more accurate system modeling, statistical models, and physical constraints than the conventional filtered backprojection (FBP) method. Because of the ill posedness of the reconstruction problem, a roughness penalty is often imposed on the solution to control noise. To avoid smoothing of edges, which are important image attributes, various edge-preserving regularization methods have been proposed. Most of these schemes rely on information from local neighborhoods to determine the presence of edges. In this paper, we propose a cost function that incorporates nonlocal boundary information into the regularization method. We use an alternating minimization algorithm with deterministic annealing to minimize the proposed cost function, jointly estimating region boundaries and object pixel values. We apply variational techniques implemented using level-sets methods to update the boundary estimates; then, using the most recent boundary estimate, we minimize a space-variant quadratic cost function to update the image estimate. For the positron emission tomography transmission reconstruction application, we compare the bias-variance tradeoff of this method with that of a \\\"conventional\\\" penalized-likelihood algorithm with local Huber roughness penalty.\",\n \"Title: Analysis of observer performance in known-location tasks for tomographic image reconstruction\\nYear: 2006\\n\\nAbstract: We consider the task of detecting a statistically varying signal of known location on a statistically varying background in a reconstructed tomographic image. We analyze the performance of linear observer models in this task. We show that, if one chooses a suitable reconstruction method, a broad family of linear observers can exactly achieve the optimal detection performance attainable with any combination of a linear observer and linear reconstructor. This conclusion encompasses several well-known observer models from the literature, including models with a frequency-selective channel mechanism and certain types of internal noise. Interestingly, the \\\"optimal\\\" reconstruction methods are unregularized and in some cases quite unconventional. These results suggest that, for the purposes of designing regularized reconstruction methods that optimize lesion detectability, known-location tasks are of limited use.\",\n \"Title: Regularized fieldmap estimation in MRI\\nYear: 2006\\n\\nAbstract: In fast MR imaging with long readout times, such as echo- planar imaging (EPI) and spiral scans, it is important to cor- rect for the effects of field inhomogeneity to reduce image distortion and blurring. Such corrections require an accurate field map, a map of the off-resonance frequency at each voxel. Standard fieldmap estimation methods yield noisy fieldmaps, particularly in image regions having low spin density. This paper describes regularized methods for fieldmap estimation. These methods exploit the factthatfieldmaps are smooth func- tions. Efficient convergent algorithms are given even though the problem is highly nonlinear. Results show that the pro- posed regularized methods significantly improve the quality of fieldmap estimates relative to conventional unregularized methods.\",\n \"Title: Spatial resolution analysis of iterative image reconstruction with separate regularization of real and imaginary parts\\nYear: 2006\\n\\nAbstract: A common method of improving the conditioning in itera- tive image reconstruction is to include regularization in the re- construction algorithm. One such regularization is the rough- ness penalty, which when used in the algorithm encourages smoother images. For complex valued images, the rough- ness penalty typically penalizes equally the real and imagi- nary parts. The desired resolution of the reconstructed image can then be evaluated using the local impulse response. A fast algorithm to calculate it was developed for the typical rough- ness penalty, used for matching the regularization parameter expediently to the desired resolution. For some cases its ad- vantageous to penalize independently the real and imaginary parts. This paper proposes a fast algorithm to calculate the local impulse response for that penalty and applies it to an fMRI reconstruction problem.\",\n \"Title: Regularization for uniform spatial resolution properties in penalized-likelihood image reconstruction.\\nYear: 2000\\n\\nAbstract: Traditional space-invariant regularization methods in tomo- graphic image reconstruction using penalized-likelihood estimators pro- duce images with nonuniformspatial resolution properties. The local point spread functions that quantify the local smoothing properties of such es- timators are not only space-variant and asymmetric, but are also object- dependent even for space-invariant imaging systems. We propose a new quadratic regularization scheme for shift-invariant imaging systems that yields increased spatial uniformity motivated by the least-squares fitting of a parameterized local impulse response to a desired global response. We demonstrate the increased spatial uniformity of this new method versus conventional quadratic regularization schemes through an investigation of local point spread functions, and through reconstruction of thorax phan- tom data with known structure.\",\n \"Title: Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT\\nYear: 2006\\n\\nAbstract: In order to reconstruct attenuation maps with improved spatial resolution and quantitative accuracy, we developed an approximate method of incorporating system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission reconstruction. Our method approximately models the blur caused by the finite intrinsic detector resolution, the nonideal source collimation and detector collimation. We derived the formulation using the optimization transfer principle as in the derivation of the OSTR algorithm. The formulation includes one forward-blur step and one back-blur step, which do not severely slow down reconstruction. The formulation could be applicable to various transmission geometries, such as point-source, line-source, and sheet-source systems. Through computer simulations of the MCAT phantom and transmission measurements of the air-filled Data Spectrum Deluxe single photo emission computed tomography (SPECT) Phantom on a system which employed a cone-beam geometry and a system which employed a scanning-line-source geometry, we showed that incorporation of RC increased spatial resolution and improved the quantitative accuracy of reconstruction. In simulation studies, attenuation maps reconstructed with RC correction improved the quantitative accuracy of emission reconstruction.\",\n \"Title: REGULARIZED B1+ MAP ESTIMATION IN MRI\\nYear: 2007\\n\\nAbstract: A challenge in MR imaging is that RF transmit coils produce non-uniform field strengths, so an excitation pulse will produce tip angles that vary substantially from the desired tip angle over the field of view. For parallel transmit excitation (using a coil array), it is important to have a map of the B1+ field strength (and phase) for RF pulse design. Standard B1+ map estimation methods perform poorly in image regions with low spin density. This paper describes a regularized method for B1+ map estimation using MR scans for each coil and for two or more tip angles. Using these scans and exploiting the fact that maps are generally smooth, the iterative algorithm estimates both the magnitude and phase at each coil's B1+ map. Results from both simulations and real MR data show significant improvements over conventional unregularized methods for B1 + mapping.\",\n \"Title: MODEL-BASED MR IMAGE RECONSTRUCTION WITH COMPENSATION FOR THROUGH-PLANE FIELD INHOMOGENEITY\\nYear: 2007\\n\\nAbstract: To improve image quality in susceptibility-weighted MR imaging, it is important to correct for the effects of field inhomogeneity. In particular, susceptibility differences between air and tissue induce magnetic field nonuniformity; often those susceptibility effects have nonzero through-plane gradients that lead to spin dephasing across the slice within each voxel. If uncorrected, these through-plane gradients cause signal loss in the reconstructed images. Several methods exist for reconstructing MR images with compensation for field inhomogeneity, but most of these methods, even the model-based iterative ones, treat the inhomogeneity within each voxel as being a constant, thus ignoring the through-plane gradient effects. This paper describes a model-based iterative method for reconstructing MR images with compensation for field inhomogeneity that accounts for the slice profile and the through-plane gradients of the field inhomogeneity (assumed to be determined by a pre-scan). In particular, this paper describes an accelerated algorithm for implementing the forward model and its adjoint as needed in a conjugate gradient algorithm for iterative MR image reconstruction.\",\n \"Title: An expanded theoretical treatment of iteration-dependent majorize-minimize algorithms.\\nYear: 2007\\n\\nAbstract: The majorize-minimize (MM) optimization technique has received considerable attention in signal and image processing applications, as well as in statistics literature. At each iteration of an MM algorithm, one constructs a tangent majorant function that majorizes the given cost function and is equal to it at the current iterate. The next iterate is obtained by minimizing this tangent majorant function, resulting in a sequence of iterates that reduces the cost function monotonically. A well-known special case of MM methods are expectation-maximization algorithms. In this paper, we expand on previous analyses of MM, due to Fessler and Hero, that allowed the tangent majorants to be constructed in iteration-dependent ways. Also, this paper overcomes an error in one of those earlier analyses. There are three main aspects in which our analysis builds upon previous work. First, our treatment relaxes many assumptions related to the structure of the cost function, feasible set, and tangent majorants. For example, the cost function can be nonconvex and the feasible set for the problem can be any convex set. Second, we propose convergence conditions, based on upper curvature bounds, that can be easier to verify than more standard continuity conditions. Furthermore, these conditions allow for considerable design freedom in the iteration-dependent behavior of the algorithm. Finally, we give an original characterization of the local region of convergence of MM algorithms based on connected (e.g., convex) tangent majorants. For such algorithms, cost function minimizers will locally attract the iterates over larger neighborhoods than typically is guaranteed with other methods. This expanded treatment widens the scope of the MM algorithm designs that can be considered for signal and image processing applications, allows us to verify the convergent behavior of previously published algorithms, and gives a fuller understanding overall of how these algorithms behave.\",\n \"Title: Discriminative sliding preserving regularization in medical image registration\\nYear: 2009\\n\\nAbstract: Sliding effects often occur along tissue/organ boundaries. For instance, it is widely observed that the lung and diaphragm slide against the rib cage and the atria during breathing. Conventional homogeneous smooth registration methods fail to address this issue. Some recent studies preserve motion discontinuities by either using joint registration/segmentation or utilizing robust regularization energy on the motion field. However, allowing all types of discontinuities is not strict enough for physical deformations. In particular, flows that generate local vacuums or mass collisions should be discouraged by the energy functional. In this study, we propose a regularization energy that encodes a discriminative treatment of different types of motion discontinuities. The key idea is motivated by the Helmholtz-Hodge decomposition, and regards the underlying motion flow as a superposition of a solenoidal component, an irrotational component and a harmonic part. The proposed method applies a homogeneous penalty on the divergence, discouraging local volume change caused by the irrotational component, thus avoiding local vacuum or collision; it regularizes the curl field with a robust functional so that the resulting solenoidal component vanishes almost everywhere except on a singular set where the large shear values are preserved. This singularity set corresponds to sliding interfaces. Preliminary tests with both simulated and clinical data showed promising results.\",\n \"Title: Regularized MR coil sensitivity estimation using augmented Lagrangian methods\\nYear: 2012\\n\\nAbstract: Several magnetic resonance (MR) parallel imaging techniques require explicit estimates of the receive coil sensitivity profiles. These estimates must be accurate over both the object and its surrounding regions to avoid generating artifacts in the reconstructed images. Statistical estimation methods provide robust sensitivity estimates but can be computationally expensive. In this paper, we propose an augmented Lagrangian (AL) based method that estimates the coil sensitivity by minimizing a quadratic cost function. This method reformulates the finite differencing matrix to allow for exact alternating minimization steps. We also explore a variation of our algorithm that involves intermediate updating of the Lagrange multipliers. We demonstrate that our proposed algorithm converges in half the time of the traditional conjugate gradient method with a circulant preconditioner (PCG) on a real data set.\",\n \"Title: An accelerated iterative reweighted least squares algorithm for compressed sensing MRI\\nYear: 2010\\n\\nAbstract: Compressed sensing for MRI (CS-MRI) attempts to recover an object from undersampled k-space data by minimizing sparsity-promoting regularization criteria. The iterative reweighted least squares (IRLS) algorithm can perform the minimization task by solving iteration-dependent linear systems, recursively. However, this process can be slow as the associated linear system is often poorly conditioned for ill-posed problems. We propose a new scheme based on the matrix inversion lemma (MIL) to accelerate the solving process. We demonstrate numerically for CS-MRI that our method provides significant speed-up compared to linear and nonlinear conjugate gradient algorithms, thus making it a promising alternative for such applications.\",\n \"Title: Joint estimation of image and fieldmap in parallel MRI using single-shot acquisitions\\nYear: 2010\\n\\nAbstract: We propose a method for joint reconstruction of dynamic images and fieldmaps in parallel MRI, using single-shot trajectories. We exploit the sensitivity encoding from parallel imaging to reduce the length of acquisition and essentially perform joint reconstruction using just one full k-space dataset. We also explore the use of modified trajectories (both EPI and spiral) that provide full coverage of k-space and also contain enough inherent time differences to permit accurate fieldmap estimation. Finally we improve the efficiency of the reconstruction algorithm by using a linearization technique for fieldmap estimation, which allows the use of the conjugate gradient algorithm.\",\n \"Title: MODEL-BASED IMAGE RECONSTRUCTION FOR MRI.\\nYear: 2010\\n\\nAbstract: Magnetic resonance imaging (MRI) is a sophisticated and versatile medical imaging modality. Traditionally, MR images are reconstructed from the raw measurements by a simple inverse 2D or 3D fast Fourier transform (FFT). However, there are a growing number of MRI applications where a simple inverse FFT is inadequate, e.g., due to non-Cartesian sampling patterns, non-Fourier physical effects, nonlinear magnetic fields, or deliberate under-sampling to reduce scan times. Such considerations have led to increasing interest in methods for model-based image reconstruction in MRI.\",\n \"Title: Improved Robust PCA using low-rank denoising with optimal singular value shrinkage\\nYear: 2014\\n\\nAbstract: We study the robust PCA problem of reliably recovering a low-rank signal matrix from a signal-plus-noise-plus-outliers matrix. We analytically characterize the extent to which the singular vectors of the signal-plus-noise-plus-outliers matrix can be degraded by outliers and discuss why a recently proposed method for robust PCA that exploits outlier sparsity to improve low-rank estimation will produce suboptimal low-rank matrix estimates in the presence of noise. Next, we propose a new iterative algorithm for robust PCA that utilizes an optimal, data-driven low-rank matrix estimator (OptShrink). Finally, we show that the proposed approach yields superior background subtraction on a computer vision dataset.\",\n \"Title: Fast MR image reconstruction with orthogonal wavelet regularization via shift-variant shrinkage\\nYear: 2014\\n\\nAbstract: Algorithms with Lipschitz bounds such as ISTA and FISTA are useful for solving optimization problems with sparsity-promoting regularizers. However, they can be slow in applications that involve shift-variant system matrices. One example of such an application is MRI with multiple sensitivity coils. We propose a reconstruction algorithm for wavelet regularized SENSE MR image reconstruction that exploits the spatial localization of the wavelet basis and the shift-variant behavior of the MR system matrix to accelerate algorithm convergence. Our results indicate that the proposed method is faster than state-of-the-art variable splitting algorithms in terms of convergence speed for a SENSE-type reconstruction problem even when the variable splitting methods are tuned carefully. Unlike variable splitting methods, the proposed method requires no convergence parameter tuning.\",\n \"Title: Model-based estimation of T2 maps with dual-echo steady-state MR imaging\\nYear: 2014\\n\\nAbstract: Fast and accurate quantification of spin-spin relaxation parameter T2 is of importance for clinical MRI applications. Classical spin echo (SE) sequences yield straightforward T2 estimates, but require undesirably long scans. By contrast, steady-state sequences such as the Dual-Echo Steady-State (DESS) sequence are considerably faster, but produce signals that depend on more complex functions of both desired and nuisance parameters. Conventional method-of-moments estimators exhibit systematic error because of the approximations used to bypass nuisance parameter estimation. To improve T2 mapping accuracy, we propose a novel, model-based approach to this nonlinear estimation problem. We use a fast scan to estimate nuisance parameters M0* and T1, and then use the exact DESS signal model for regularized T2 estimation from DESS data, with minimal approximations. MR brain simulation results show that the proposed approach substantially improves T2 estimation accuracy and precision, compared to conventional method-of-moments estimators.\",\n \"Title: Benefits of Position-Sensitive Detectors for Radioactive Source Detection\\nYear: 2010\\n\\nAbstract: There are many systems for counting photons such as gamma-rays emitted from radioactive sources. Many of these systems are also position-sensitive, which means that the system provides directional information about recorded events. This paper investigates whether or not the additional information provided by position-sensitive capability improves the performance of detecting a point-source in background. We analyze the asymptotic performance of the generalized likelihood ratio test (GLRT) and a test based on the maximum-likelihood (ML) estimate of the source intensity for systems with and without position-sensitive capability. When the background intensity is known and detector sensitivity is spatially uniform, we prove that position-sensitive capability increases the area under the receiver operating characteristic curve (AUC). For cases when detector sensitivity is nonuniform or background intensity is unknown, we provide numerical results to illustrate the effect of the parameters on detection performance.\",\n \"Title: Image restoration using non-circulant shift-invariant system models\\nYear: 2012\\n\\nAbstract: Image restoration is a well studied problem and there are several proposed methods for deblurring and denoising. Recently, there is increasing interest in iterative schemes that employ non-quadratic regularizers, especially edge-preserving like Total Variation (TV) and sparsity promoting like l1 regularization. Most methods make simplifying assumptions concerning the system model and the most common one is the use of a circulant blurring model because it facilitates using the FFT. In this work we focus on a more realistic non-circulant blurring model and apply existing algorithms for image restoration with non-quadratic regularization, tailored to work with our non-circulant model.\",\n \"Title: Optimization transfer approach to joint registration / reconstruction for motion-compensated image reconstruction\\nYear: 2010\\n\\nAbstract: Motion artifacts in image reconstruction problems can be reduced by performing image motion estimation and image reconstruction jointly using a penalized-likelihood cost function. However, updating the motion parameters by conventional gradient-based iterations can be computationally demanding due to the system model required in inverse problems. This paper describes an optimization transfer approach that leads to minimization steps for the motion parameters that have comparable complexity to those needed in image registration problems. This approach can simplify the implementation of motion-compensated image reconstruction (MCIR) methods when the motion parameters are estimated jointly with the reconstructed image.\",\n \"Title: Cramér Rao bound analysis of joint B1/T1 mapping methods in MRI\\nYear: 2010\\n\\nAbstract: In MRI, RF field inhomogeneity (B1) and relaxation effects (T1) significantly affect both B1 and T1 mapping. Simultaneous joint estimation of both B1 and T1 has the potential to greatly improve both B1 and T1 estimation. This paper analyzes the Cramér Rao Bound for joint B1, T1 estimation using common B1 and T1 pulse sequences. This analysis aids choosing pulse sequences and parameters given desired levels of B1 and T1 accuracy and the inherent trade off between the two mappings.\",\n \"Title: Non-Cartesian MRI Reconstruction With Automatic Regularization Via Monte-Carlo SURE\\nYear: 2013\\n\\nAbstract: Magnetic resonance image (MRI) reconstruction from undersampled k-space data requires regularization to reduce noise and aliasing artifacts. Proper application of regularization however requires appropriate selection of associated regularization parameters. In this work, we develop a data-driven regularization parameter adjustment scheme that minimizes an estimate [based on the principle of Stein's unbiased risk estimate (SURE)] of a suitable weighted squared-error measure in k-space. To compute this SURE-type estimate, we propose a Monte-Carlo scheme that extends our previous approach to inverse problems (e.g., MRI reconstruction) involving complex-valued images. Our approach depends only on the output of a given reconstruction algorithm and does not require knowledge of its internal workings, so it is capable of tackling a wide variety of reconstruction algorithms and nonquadratic regularizers including total variation and those based on the l1-norm. Experiments with simulated and real MR data indicate that the proposed approach is capable of providing near mean squared-error optimal regularization parameters for single-coil undersampled non-Cartesian MRI reconstruction.\",\n \"Title: Sure-based parameter selection for parallel MRI reconstruction using GRAPPA and sparsity\\nYear: 2013\\n\\nAbstract: New methods have been developed for parallel MRI reconstruction combining GRAPPA and sparsity. One impediment to the practical application of such methods is selecting a regularization parameter that acceptably balances the contributions of GRAPPA and sparsity. We propose a broadly applicable Monte-Carlo-based approximation to Stein's unbiased risk estimate (SURE) for a suitable weighted mean-squared error (WMSE) metric. Applying this approximation to predict the WMSE-optimal tuning parameter for sparsity-based reconstruction, we are able to tune our parameter to achieve nearly MSE-optimal performance. In our simulations, we vary the noise level in the simulated data and use our Monte-Carlo method to tune the reconstruction to the noise level automatically.\",\n \"Title: Globally convergent image reconstruction for emission tomography using relaxed ordered subsets algorithms.\\nYear: 2003\\n\\nAbstract: We present two types of globally convergent relaxed ordered subsets (OS) algorithms for penalized-likelihood image reconstruction in emission tomography: modified block sequential regularized expectation-maximization (BSREM) and relaxed OS separable paraboloidal surrogates (OS-SPS). The global convergence proof of the existing BSREM (De Pierro and Yamagishi, 2001) required a few a posteriori assum...\",\n \"Title: Undersampled Phase Retrieval with Outliers.\\nYear: 2015\\n\\nAbstract: This paper proposes a general framework for reconstructing sparse images from undersampled (squared)magnitude data corrupted with outliers and noise. This phase retrieval method uses a layered approach, combining repeated minimization of a convex majorizer (surrogate for a nonconvex objective function), and iterative optimization of that majorizer using a preconditioned variant of the alternating ...\",\n \"Title: Joint Design of Excitation k-Space Trajectory and RF Pulse for Small-Tip 3D Tailored Excitation in MRI.\\nYear: 2016\\n\\nAbstract: We propose a new method for the joint design of k-space trajectory and RF pulse in 3D small-tip tailored excitation. Designing time-varying RF and gradient waveforms for a desired 3D target excitation pattern in MRI poses a non-linear, non-convex, constrained optimization problem with relatively large problem size that is difficult to solve directly. Existing joint pulse design approaches are therefore typically restricted to predefined trajectory types such as EPI or stack-of-spirals that intrinsically satisfy the gradient maximum and slew rate constraints and reduce the problem size (dimensionality) dramatically, but lead to suboptimal excitation accuracy for a given pulse duration. Here we use a 2nd-order B-spline basis that can be fitted to an arbitrary k-space trajectory, and allows the gradient constraints to be implemented efficiently. We show that this allows the joint optimization problem to be solved with quite general k-space trajectories. Starting from an arbitrary initial trajectory, we first approximate the trajectory using B-spline basis, and then optimize the corresponding coefficients. We evaluate our method in simulation using four different k-space initializations: stack-of-spirals, SPINS, KT-points, and a new method based on KT-points. In all cases, our approach leads to substantial improvement in excitation accuracy for a given pulse duration. We also validated our method for inner-volume excitation using phantom experiments. The computation is fast enough for online applications.\",\n \"Title: Relaxed Linearized Algorithms for Faster X-Ray CT Image Reconstruction.\\nYear: 2016\\n\\nAbstract: Statistical image reconstruction (SIR) methods are studied extensively for X-ray computed tomography (CT) due to the potential of acquiring CT scans with reduced X-ray dose while maintaining image quality. However, the longer reconstruction time of SIR methods hinders their use in X-ray CT in practice. To accelerate statistical methods, many optimization techniques have been investigated. Over-rel...\",\n \"Title: Model-Based, One-Sided, Time-Of-Flight Terahertz Image Reconstruction\\nYear: 2014\\n\\nAbstract: In the last decade, terahertz-mode imaging has received increased attention for non-destructive testing applications due to its ability to penetrate many materials while maintaining a small wavelength. This paper describes a model-based reconstruction algorithm that is able to image defects in the spray-on foam insulation (SOFT) used in aerospace applications that has been sprayed on a reflective metal hull. In this situation, X-ray based imaging is infeasible since only one side of the hull is accessible in flight.This paper models the object as a grid of materials, each section of which has a constant index of refraction. The delay between the transmission and reception of a THz pulse is related to the integral of the index of refraction along the pulse's path, and we adapt computed tomography (CT) methods to reconstruct an image of an object's index of refraction.We present the results of our reconstruction method using real data of the timing of THz pulses passing through a block of SOFT with holes of a known location and radius. The resulting image of the block has a low level of noise, but contains artifacts due to the limited angular range of one-sided imaging and due to the narrow beam approximation used in the forward model.\",\n \"Title: Iterative Weighted Risk Estimation For Nonlinear Image Restoration With Analysis Priors\\nYear: 2012\\n\\nAbstract: Image acquisition systems invariably introduce blur, which necessitates the use of deblurring algorithms for image restoration. Restoration techniques involving regularization require appropriate selection of the regularization parameter that controls the quality of the restored result. We focus on the problem of automatic adjustment of this parameter for nonlinear image restoration using analysis-type regularizers such as total variation (TV). For this purpose, we use two variants of Stein's unbiased risk estimate (SURE), Predicted-SURE and Projected-SURE, that are applicable for parameter selection in inverse problems involving Gaussian noise. These estimates require the Jacobian matrix of the restoration algorithm evaluated with respect to the data. We derive analytical expressions to recursively update the desired Jacobian matrix for a fast variant of the iterative reweighted least-squares restoration algorithm that can accommodate a variety of regularization criteria. Our method can also be used to compute a nonlinear version of the generalized cross-validation (NGCV) measure for parameter tuning. We demonstrate using simulations that Predicted-SURE, Projected-SURE, and NGCV-based adjustment of the regularization parameter yields near-MSE-optimal results for image restoration using TV, an analysis-type L-1-Regularization, and a smooth convex edge-preserving regularizer.\",\n \"Title: Fast Edge-Preserving Image Denoising Via Group Coordinate Descent On The Gpu\\nYear: 2014\\n\\nAbstract: We present group coordinate descent algorithms for edge-preserving image denoising that are particularly well-suited to the graphics processing unit (GPU). The algorithms decouple the denoising optimization problem into a set of iterated, independent one-dimensional problems. We provide methods to handle both differentiable regularizers and the absolute value function using the majorize-minimize technique. Specifically, we use quadratic majorizers with Huber curvatures for differentiable potentials and a duality approach for the absolute value function. Preliminary experimental results indicate that the algorithms converge remarkably quickly in time.\",\n \"Title: Joint estimation of activity distribution and attenuation map for TOF-PET using alternating direction method of multiplier\\nYear: 2016\\n\\nAbstract: Recent advances in TOF PET joint estimation of activity and attenuation showed that activity and attenuation can be determined up to a global constant scale without severe crosstalk. MLAA was first proposed to estimate activity and attenuation map simultaneously, and then MLACF was developed to estimate activity and attenuation compensation factor (ACF). MLAA incorporated prior knowledge on the zero attenuation value outside body area to determine global scalar, but was slow to converge. MLACF converged much faster than MLAA, but required knowing total activity level in advance. We propose a new optimization method based on variable splitting and alternating direction method of multiplier (MLADMM). Our proposed MLADMM achieved fast convergence rate comparable to MLACF without knowing total activity level. MLADMM also has a potential to use more sophisticated MR-based prior for attenuation in PET-MR.\",\n \"Title: Low-rank and Adaptive Sparse Signal (LASSI) Models for Highly Accelerated Dynamic Imaging.\\nYear: 2017\\n\\nAbstract: Sparsity-based approaches have been popular in many applications in image processing and imaging. Compressed sensing exploits the sparsity of images in a transform domain or dictionary to improve image recovery from undersampled measurements. In the context of inverse problems in dynamic imaging, recent research has demonstrated the promise of sparsity and low-rank techniques. For example, the pat...\",\n \"Title: Fast Variance Prediction for Iteratively Reconstructed CT Images With Locally Quadratic Regularization.\\nYear: 2017\\n\\nAbstract: Predicting noise properties of iteratively reconstructed CT images is useful for analyzing reconstruction methods; for example, local noise power spectrum (NPS) predictions may be used to quantify the detectability of an image feature, to design regularization methods, or to determine dynamic tube current adjustment during a CT scan. This paper presents a method for fast prediction of reconstructe...\",\n \"Title: Towards a theoretical analysis of PCA for heteroscedastic data\\nYear: 2016\\n\\nAbstract: Principal Component Analysis (PCA) is a method for estimating a subspace given noisy samples. It is useful in a variety of problems ranging from dimensionality reduction to anomaly detection and the visualization of high dimensional data. PCA performs well in the presence of moderate noise and even with missing data, but is also sensitive to outliers. PCA is also known to have a phase transition when noise is independent and identically distributed; recovery of the subspace sharply declines at a threshold noise variance. Effective use of PCA requires a rigorous understanding of these behaviors. This paper provides a step towards an analysis of PCA for samples with heteroscedastic noise, that is, samples that have non-uniform noise variances and so are no longer identically distributed. In particular, we provide a simple asymptotic prediction of the recovery of a one-dimensional subspace from noisy heteroscedastic samples. The prediction enables: a) easy and efficient calculation of the asymptotic performance, and b) qualitative reasoning to understand how PCA is impacted by heteroscedasticity (such as outliers).\",\n \"Title: Detector Blur and Correlated Noise Modeling for Digital Breast Tomosynthesis Reconstruction.\\nYear: 2018\\n\\nAbstract: This paper describes a new image reconstruction method for digital breast tomosynthesis (DBT). The new method incorporates detector blur into the forward model. The detector blur in DBT causes correlation in the measurement noise. By making a few approximations that are reasonable for breast imaging, we formulated a regularized quadratic optimization problem with a data-fit term that incorporates ...\",\n \"Title: Efficient Sum of Outer Products Dictionary Learning (SOUP-DIL) - The $\\\\ell_0$ Method.\\nYear: 2015\\n\\nAbstract: The sparsity of natural signals and images in a transform domain or dictionary has been extensively exploited in several applications such as compression, denoising and inverse problems. More recently, data-driven adaptation of synthesis dictionaries has shown promise in many applications compared to fixed or analytical dictionary models. However, dictionary learning problems are typically non-convex and NP-hard, and the usual alternating minimization approaches for these problems are often computationally expensive, with the computations dominated by the NP-hard synthesis sparse coding step. In this work, we investigate an efficient method for $\\\\ell_{0}$ \\\"norm\\\"-based dictionary learning by first approximating the training data set with a sum of sparse rank-one matrices and then using a block coordinate descent approach to estimate the unknowns. The proposed block coordinate descent algorithm involves efficient closed-form solutions. In particular, the sparse coding step involves a simple form of thresholding. We provide a convergence analysis for the proposed block coordinate descent approach. Our numerical experiments show the promising performance and significant speed-ups provided by our method over the classical K-SVD scheme in sparse signal representation and image denoising.\",\n \"Title: Efficient, Convergent SENSE MRI Reconstruction for Nonperiodic Boundary Conditions via Tridiagonal Solvers.\\nYear: 2017\\n\\nAbstract: Undersampling is an effective method for reducing scan acquisition time for MRI. Strategies for accelerated MRI, such as parallel MRI and compressed sensing MRI present challenging image reconstruction problems with nondifferentiable cost functions and computationally demanding operations. Variable splitting (VS) can simplify implementation of difficult image reconstruction problems, such as the c...\",\n \"Title: LASSI: A low-rank and adaptive sparse signal model for highly accelerated dynamic imaging\\nYear: 2016\\n\\nAbstract: Sparsity-based approaches have been popular in many applications in image processing and imaging. Recent research has shown the usefulness of sparsity or low-rank techniques for solving inverse problems such as those in dynamic imaging. In particular, the imaged temporal data sequence is modeled as a sum of low-rank and sparse components that are estimated from measurements. In this work, we instead decompose the temporal image sequence into a low-rank component and a component whose spatiotemporal patches are assumed sparse in some adaptive dictionary domain. We present a methodology to jointly estimate the underlying signal components and the spatiotemporal dictionary from highly under-sampled measurements. Our numerical experiments demonstrate the promising performance of our scheme for dynamic magnetic resonance image reconstruction from undersampled k-t space data.\",\n \"Title: Low dose CT image reconstruction with learned sparsifying transform\\nYear: 2017\\n\\nAbstract: A major challenge in computed tomography (CT) is to reduce X-ray dose to a low or even ultra-low level while maintaining the high quality of reconstructed images. We propose a new method for CT reconstruction that combines penalized weighted-least squares reconstruction (PWLS) with regularization based on a sparsifying transform (PWLS-ST) learned from a dataset of numerous CT images. We adopt an alternating algorithm to optimize the PWLS-ST cost function that alternates between a CT image update step and a sparse coding step. We adopt a relaxed linearized augmented Lagrangian method with ordered-subsets (relaxed OS-LALM) to accelerate the CT image update step by reducing the number of forward and backward projections. Numerical experiments on the XCAT phantom show that for low dose levels, the proposed PWLS-ST method dramatically improves the quality of reconstructed images compared to PWLS reconstruction with a nonadaptive edge-preserving regularizer (PWLS-EP).\",\n \"Title: Efficient learning of dictionaries with low-rank atoms\\nYear: 2016\\n\\nAbstract: Sparsity-based techniques have been popular in many applications in signal and image processing. In particular, the data-driven adaptation of sparse signal models such as the synthesis model has shown promise in applications. However, dictionary learning problems are typically nonconvex and NP-hard, and the usual alternating minimization approaches for learning are often expensive and lack convergence guarantees. In this work, we investigate efficient methods for learning structured synthesis dictionaries. In particular, we model the atoms (columns) of the dictionary, after reshaping, as low-rank. We propose a block coordinate descent algorithm for our dictionary learning model that involves efficient optimal updates. We also provide a convergence analysis of the proposed method for a highly nonconvex problem. Our numerical experiments show the usefulness of our schemes in inverse problem settings, such as in dynamic MRI and inpainting.\",\n \"Title: Sum Of Outer Products Dictionary Learning For Inverse Problems\\nYear: 2016\\n\\nAbstract: The data-driven adaptation of synthesis dictionaries has been exploited in many applications in signal processing and imaging. This paper exploits efficient methods for aggregate sparsity penalized dictionary learning by first approximating the matrix of image patches with a sum of sparse rank-one matrices (outer products) and then using a block coordinate descent approach to estimate the unknowns, and applies such sum of outer products methodologies for the problem of dictionary-blind image reconstruction. We propose efficient algorithms for adaptive image reconstruction and provide a convergence analysis for our methods. Our numerical experiments show the promising performance provided by the proposed schemes over recent methods in compressed sensing-based image reconstruction.\",\n \"Title: Dictionary-free MRI parameter estimation via kernel ridge regression\\nYear: 2017\\n\\nAbstract: MRI parameter quantification has diverse applications, but likelihood-based methods typically require nonconvex optimization due to nonlinear signal models. To avoid expensive grid searches used in prior works, we propose to learn a nonlinear estimator from simulated training examples and (approximate) kernel ridge regression. As proof of concept, we apply kernel-based estimation to quantify six parameters per voxel describing the steady-state magnetization dynamics of two water compartments from simulated data. In relevant regions of fast-relaxing compartmental fraction estimates, kernel estimation achieves comparable mean-squared error as grid search, with dramatically reduced computation.\",\n \"Title: Convolutional Dictionary Learning: Acceleration and Convergence.\\nYear: 2018\\n\\nAbstract: Convolutional dictionary learning (CDL or sparsifying CDL) has many applications in image processing and computer vision. There has been growing interest in developing efficient algorithms for CDL, mostly relying on the augmented Lagrangian (AL) method or the variant alternating direction method of multipliers (ADMM). When their parameters are properly tuned, AL methods have shown fast convergence...\",\n \"Title: Challenges and Open Problems in Signal Processing: Panel Discussion Summary from ICASSP 2017 [Panel and Forum].\\nYear: 2017\\n\\nAbstract: This column summarizes the panel on open problems in signal processing, which took place on 5 March 2017 at the International Conference on Acoustics, Speech, and Signal Processing (ICASSP) in New Orleans, Louisiana. The goal of the panel was to draw attention to some of the challenges and open problems in various areas of signal processing and generate discussion on future research areas that can...\",\n \"Title: Efficient Sum of Outer Products Dictionary Learning (SOUP-DIL) and Its Application to Inverse Problems.\\nYear: 2017\\n\\nAbstract: The sparsity of signals in a transform domain or dictionary has been exploited in applications, such as compression, denoising, and inverse problems. More recently, data-driven adaptation of synthesis dictionaries has shown promise compared to analytical dictionary models. However, dictionary learning problems are typically nonconvex and NP-hard, and the usual alternating minimization approaches f...\",\n \"Title: Adaptive sparse modeling and shifted-poisson likelihood based approach for low-dosect image reconstruction\\nYear: 2017\\n\\nAbstract: Recent research in computed tomographic imaging has focused on developing techniques that enable reduction of the X-ray radiation dose without loss of quality of the reconstructed images or volumes. While penalized weighted-least squares (PWLS) approaches have been popular for CT image reconstruction, their performance degrades for very low dose levels due to the inaccuracy of the underlying WLS statistical model. We propose a new formulation for low-dose CT image reconstruction based on a shifted-Poisson model based likelihood function and a data-adaptive regularizer using the sparsifying transform model for images. The sparsifying transform is pre-learned from a dataset of patches extracted from CT images. The nonconvex cost function of the proposed penalized-likelihood reconstruction with sparsifying transforms regularizer (PL-ST) is optimized by alternating between a sparse coding step and an image update step. The image update step deploys a series of convex quadratic majorizers that are optimized using a relaxed linearized augmented Lagrangian method with ordered-subsets, reducing the number of (expensive) forward and backward projection operations. Numerical experiments show that for low dose levels, the proposed data-driven PL-ST approach outperforms prior methods employing a nonadaptive edge-preserving regularizer. PL-ST also outperforms prior PWLS-ST approach at very low X-ray doses.\",\n \"Title: Fast Spatial Resolution Analysis of Quadratic Penalized Least-Squares Image Reconstruction With Separate Real and Imaginary Roughness Penalty: Application to fMRI.\\nYear: 2018\\n\\nAbstract: Penalized least-squares iterative image reconstruction algorithms used for spatial resolution-limited imaging, such as functional magnetic resonance imaging (fMRI), commonly use a quadratic roughness penalty to regularize the reconstructed images. When used for complex-valued images, the conventional roughness penalty regularizes the real and imaginary parts equally. However, these imaging methods...\",\n \"Title: Image Reconstruction for Limited-Angle Electron Beam X-Ray Computed Tomography With Energy-Integrating Detectors for Multiphase Flows.\\nYear: 2018\\n\\nAbstract: We propose a new iterative X-ray computed tomography (CT) reconstruction algorithm for electron beam X-ray tomography of multiphase flows in metal pipes. This application uses limited-angle projections due to the fixed configuration, and semiconductor-type energy-integrating detectors. For the data-fitting objective function, the proposed method incorporates a nonlinear Gaussian model with object-...\",\n \"Title: Online dynamic MRI reconstruction via robust subspace tracking.\\nYear: 2017\\n\\nAbstract: We propose an efficient online reconstruction algorithm for the problem of highly undersampled dynamic magnetic resonance imaging (DMRI). Our approach reconstructs the dynamic time series by processing only a small batch of frames at a time. We adapt an online subspace tracking algorithm based on manifold optimization to the DMRI reconstruction setting and propose a novel extension of the algorithm to enable robust subspace tracking based on a local low-rank plus transform sparse model. Our experiments on real and synthetic data show that proposed approach gives comparable results to methods that reconstruct the entire image series at once while requiring only a fraction of the memory and computational demand. The dramatic memory savings allows robust subspace-based methods to be applied to much larger datasets than previously allowed.\",\n \"Title: Convolutional Analysis Operator Learning: Acceleration, Convergence, Application, and Neural Networks.\\nYear: 2018\\n\\nAbstract: Convolutional operator learning is increasingly gaining attention in many signal processing and computer vision applications. Learning kernels has mostly relied on so-called local approaches that extract and store many overlapping patches across training signals. Due to memory demands, local approaches have limitations when learning kernels from large datasets -- particularly with multi-layered structures, e.g., convolutional neural network (CNN) -- and/or applying the learned kernels to high-dimensional signal recovery problems. The so-called global approach has been studied within the synthesis signal model, e.g., convolutional dictionary learning, overcoming the memory problems by careful algorithmic designs. This paper proposes a new convolutional analysis operator learning (CAOL) framework in the global approach, and develops a new convergent Block Proximal Gradient method using a Majorizer (BPG-M) to solve the corresponding block multi-nonconvex problems. To learn diverse filters within the CAOL framework, this paper introduces an orthogonality constraint that enforces a tight-frame (TF) filter condition, and a regularizer that promotes diversity between filters. Numerical experiments show that, for tight majorizers, BPG-M significantly accelerates the CAOL convergence rate compared to the state-of-the-art method, BPG. Numerical experiments for sparse-view computational tomography show that CAOL using TF filters significantly improves reconstruction quality compared to a conventional edge-preserving regularizer. Finally, this paper shows that CAOL can be useful to mathematically model a CNN, and the corresponding updates obtained via BPG-M coincide with core modules of the CNN.\",\n \"Title: Accelerated high b-value diffusion-weighted MR imaging via phase-constrained low-rank tensor model\\nYear: 2018\\n\\nAbstract: High b-value Diffusion-weighted MRI (DWI) is promising in cancer imaging but suffers from long acquisition time and low signal-to-noise ratio (SNR). We propose a low-rank tensor model that exploits correlation across both diffusion-induced signal decays and neighboring k-space samples, to accelerate the acquisition of DWI using an extended range of b-values (0 s/mm\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\n to 2500 s/mm\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\n) and limited (orthogonal only) diffusion directions, an imaging scheme that is increasingly used for brain gliomas evaluation. A phase constraint accounts for phase variations between b-values is also applied. Our method integrates parallel imaging and partial Fourier acquisition naturally, and undersamples along phase-encoding direction only. Reconstruction results using both patient and simulated data with an acceleration factor of 8 show improved SNR and reduced aliasing, as compared to parallel imaging only method as well as two other low-rank model-based methods.\",\n \"Title: Accelerated methods for low-rank plus sparse image reconstruction\\nYear: 2018\\n\\nAbstract: The low-rank plus sparse (L+S) decomposition model enables the reconstruction of undersampled dynamic magnetic resonance imaging (MRI) data. Solving for the L and S components is anonsmooth composite convex minimization problem. While current techniques for this model are based on the classical iterative soft thresholding algorithm (ISTA), accelerated methods can be applied to obtain faster rate of convergence of the algorithm. This paper proposes two alternative methods for solving the L+S problem, one based on the fast iterative shrinkage-thresholding algorithm (FISTA), and the other based on the recent proximal optimized gradient method (POGM). Numerical results suggest faster convergence than the traditional ISTA, while preserving its computational simplicity.\",\n \"Title: Image-domain material decomposition using data-driven sparsity models for dual-energy CT\\nYear: 2018\\n\\nAbstract: Penalized weighted least squares (PWLS) with better image priors is a promising way to develop improved image-domain dual-energy CT (DECT) methods for achieving high quality basis material images. We propose a new method for DECT that combines conventional PWLS estimation with regularization based on sparsifying transforms (DECT-ST) learned from datasets of numerous CT images. Numerical experiments with phantom and patient data show that the proposed method significantly improves the image quality over direct matrix inversion decomposition and over PWLS decomposition with an edge-preserving hyperbola regularizer (DECT-EP).\",\n \"Title: Another Look at the Fast Iterative Shrinkage/Thresholding Algorithm (FISTA).\\nYear: 2018\\n\\nAbstract: This paper provides a new way of developing the fast iterative shrinkage/thresholding algorithm (FISTA) [A. Beck and M. Teboulle, SIAM T. Imaging Sci., 2 (2009), pp. 183-202] that is widely used for minimizing composite convex functions with a nonsmooth term such as the l(1) regularizer. In particular, this paper shows that FISTA corresponds to an optimized approach to accelerating the proximal gradient method with respect to a worst-case bound of the cost function. This paper then proposes a new algorithm that is derived by instead optimizing the step coefficients of the proximal gradient method with respect to a worst-case bound of the composite gradient mapping. The proof is based on the worst-case analysis called the performance estimation problem in [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482].\",\n \"Title: PWLS-ULTRA: An Efficient Clustering and Learning-Based Approach for Low-Dose 3D CT Image Reconstruction.\\nYear: 2018\\n\\nAbstract: The development of computed tomography (CT) image reconstruction methods that significantly reduce patient radiation exposure, while maintaining high image quality is an important area of research in low-dose CT imaging. We propose a new penalized weighted least squares (PWLS) reconstruction method that exploits regularization based on an efficient Union of Learned TRAnsforms (PWLS-ULTRA). The uni...\",\n \"Title: Image Reconstruction is a New Frontier of Machine Learning.\\nYear: 2018\\n\\nAbstract: Over past several years, machine learning, or more generally artificial intelligence, has generated overwhelming research interest and attracted unprecedented public attention. As tomographic imaging researchers, we share the excitement from our imaging perspective [item 1) in the Appendix], and organized this special issue dedicated to the theme of “Machine learning for image reconstruction.” Thi...\",\n \"Title: Adaptive Restart of the Optimized Gradient Method for Convex Optimization.\\nYear: 2018\\n\\nAbstract: First-order methods with momentum, such as Nesterov’s fast gradient method, are very useful for convex optimization problems, but can exhibit undesirable oscillations yielding slow convergence rates for some applications. An adaptive restarting scheme can improve the convergence rate of the fast gradient method, when the parameter of a strongly convex cost function is unknown or when the iterates of the algorithm enter a locally strongly convex region. Recently, we introduced the optimized gradient method, a first-order algorithm that has an inexpensive per-iteration computational cost similar to that of the fast gradient method, yet has a worst-case cost function rate that is twice faster than that of the fast gradient method and that is optimal for large-dimensional smooth convex problems. Building upon the success of accelerating the fast gradient method using adaptive restart, this paper investigates similar heuristic acceleration of the optimized gradient method. We first derive a new first-order method that resembles the optimized gradient method for strongly convex quadratic problems with known function parameters, yielding a linear convergence rate that is faster than that of the analogous version of the fast gradient method. We then provide a heuristic analysis and numerical experiments that illustrate that adaptive restart can accelerate the convergence of the optimized gradient method. Numerical results also illustrate that adaptive restart is helpful for a proximal version of the optimized gradient method for nonsmooth composite convex functions.\",\n \"Title: Asymptotic performance of PCA for high-dimensional heteroscedastic data.\\nYear: 2018\\n\\nAbstract: Principal Component Analysis (PCA) is a classical method for reducing the dimensionality of data by projecting them onto a subspace that captures most of their variation. Effective use of PCA in modern applications requires understanding its performance for data that are both high-dimensional and heteroscedastic. This paper analyzes the statistical performance of PCA in this setting, i.e., for high-dimensional data drawn from a low-dimensional subspace and degraded by heteroscedastic noise. We provide simplified expressions for the asymptotic PCA recovery of the underlying subspace, subspace amplitudes and subspace coefficients; the expressions enable both easy and efficient calculation and reasoning about the performance of PCA. We exploit the structure of these expressions to show that, for a fixed average noise variance, the asymptotic recovery of PCA for heteroscedastic data is always worse than that for homoscedastic data (i.e., for noise variances that are equal across samples). Hence, while average noise variance is often a practically convenient measure for the overall quality of data, it gives an overly optimistic estimate of the performance of PCA for heteroscedastic data.\",\n \"Title: Dictionary-Free MRI PERK: Parameter Estimation via Regression with Kernels.\\nYear: 2018\\n\\nAbstract: This paper introduces a fast, general method for dictionary-free parameter estimation in quantitative magnetic resonance imaging (QMRI) parameter estimation via regression with kernels (PERK). PERK first uses prior distributions and the nonlinear MR signal model to simulate many parameter-measurement pairs. Inspired by machine learning, PERK then takes these parameter-measurement pairs as labeled ...\",\n \"Title: Learning Dictionary-Based Unions of Subspaces for Image Denoising.\\nYear: 2018\\n\\nAbstract: Many signals of interest are well-approximated by sparse linear combinations of atomic signals from a dictionary. Equivalently, they are well-approximated by low-dimensional subspaces in a union of subspaces generated by the dictionary. A given sparsity level has an associated union of subspaces (UoS) generated by sparse combinations of correspondingly many atoms. When considering a sequence of sparsity levels, we have a sequence of unions of subspaces (SUoS) of increasing dimension. This paper considers the problem of learning such an SUoS from data. While each UoS is combinatorially large with respect to sparsity level, our learning approach exploits the fact that sparsity is structured for many signals of interest, i.e., that certain collections of atoms are more frequently used together than others. This is known as group sparsity structure and has been studied extensively when the structure is known a priori. We consider the setting where the structure is unknown, and we seek to learn it from training data. We also adapt the subspaces we obtain to improve representation and parsimony, similar to the goal of adapting atoms in dictionary learning. We illustrate the benefits of the learned dictionary-based SUoS for the problem of denoising; using a more parsimonious and representative SUoS results in improved recovery of complicated structures and edges.\",\n \"Title: Real-Time Filtering with Sparse Variations for Head Motion in Magnetic Resonance Imaging.\\nYear: 2019\\n\\nAbstract: •Sparse residual image modeling adapts Kalman filtering to temporal dynamics.•Augmented Lagrangian optimization can produce motion estimates in real time.•Adapting the process covariance estimate can improve handling of large motions.•Simulations depict improved brain activity detection with prospective correction.\",\n \"Title: Fast and convergent iterative image recovery using trained convolutional neural networks.\\nYear: 2018\\n\\nAbstract: Deep image mapping networks have been recently applied to solving some inverse problems in imaging due to their good mapping capabilities. However, the greater mapping capability can increase the chance of causing some artificial features when test images differ from training images. Combining image mapping networks with an iterative image recovery that naturally considers imaging system physics is an alternative approach to solving inverse problems. This alternative approach can avoid artificial features, by (back-)projecting the output signals of image mapping networks while considering the imaging system physics. By generalizing the state-of-the-art iterative image recovery algorithm using learned regularizer with iteration-wise image mapping networks, this paper proposes a new recurrent convolutional neural network, Momentum-Net. In addition, this paper investigates the theoretical convergence behavior of Momentum-Net. Numerical experiments show that, for ${a}$) denoising low signal-to-noise-ratio images, and ${b}$) sparse-view X-ray computed tomography, the proposed Momentum-Net achieves significantly more accurate and faster image recovery, compared to the state-of-the-art data-driven regularizer or the unsupervised autoencoding regularizer.\",\n \"Title: Efficient Dynamic Parallel MRI Reconstruction for the Low-Rank Plus Sparse Model\\nYear: 2019\\n\\nAbstract: The low-rank plus sparse (L+S) decomposition model enables the reconstruction of undersampled dynamic parallel magnetic resonance imaging data. Solving for the low rank and the sparse components involves nonsmooth composite convex optimization, and algorithms for this problem can be categorized into proximal gradient methods and variable splitting methods. This paper investigates new efficient algorithms for both schemes. While current proximal gradient techniques for the L+S model involve the classical iterative soft thresholding algorithm (ISTA), this paper considers two accelerated alternatives, one based on the fast iterative shrinkage-thresholding algorithm (FISTA) and the other with the recent proximal optimized gradient method (POGM). In the augmented Lagrangian (AL) framework, we propose an efficient variable splitting scheme based on the form of the data acquisition operator, leading to simpler computation than the conjugate gradient approach required by existing AL methods. Numerical results suggest faster convergence of the efficient implementations for both frameworks, with POGM providing the fastest convergence overall and the practical benefit of being free of algorithm tuning parameters.\",\n \"Title: LEARNED MIXED MATERIAL MODELS FOR EFFICIENT CLUSTERING BASED DUAL-ENERGY CT IMAGE DECOMPOSITION\\nYear: 2018\\n\\nAbstract: Penalized weight-least squares (PWLS) with basis material priors is a promising way to achieve high quality material decompositions for Dual-energy CT (DECT). This paper proposes a new method dubbed DECT-MULTRA for image domain DECT material decomposition that combines conventional PWLS estimation with regular-ization based on a mixed union of learned transforms (MULTRA) model. Our approach pre-learns from training data a common union of unitary transforms for all the basis materials’ patches, as well as a cross-material union of unitary transforms that captures relationships between the different basis material images. The proposed DECT-MULTRA algorithm efficiently obtains material decompositions by alternating between updating the material images and performing clustering of patches in the MULTRA model. Both these steps of the alternating algorithm have closed-form updates. Numerical experiments with the XCAT phantom show that the proposed method significantly improves image quality compared to the recent DECT-ST method that learns different sparsifying transforms for different basis materials and the DECT-EP approach that uses a non-adaptive edge-preserving hyperbola regularizer.\",\n \"Title: Convolutional analysis operator learning - Application to sparse-view CT - (Invited Paper).\\nYear: 2018\\n\\nAbstract: Convolutional analysis operator learning (CAOL) methods train an autoencoding convolutional neural network (CNN) in an unsupervised learning manner, to more accurately solve inverse problems. Block Proximal Gradient method using a Majorizer (BPG-M) achieved fast and convergent CAOL, by using sharp majorizers and the momentum terms. This paper proposes a model-based image reconstruction (MBIR) method using autoencoding CNNs trained via CAOL, for sparse-view computational tomography (CT). We apply BPG-M to rapidly and stably solve the corresponding block multi-nonconvex optimization problem. Numerical experiments show that, for sparse-view CT, 1) the proposed MBIR method outperforms the standard MBIR method using edge-preserving regularization; 2) larger parameter dimensions of autoencoding CNNs improve reconstruction accuracy of the proposed MBIR method; and 3) when using BPG-M, sharper majorization is more critical for accelerating its convergence than giving more weights on extrapolation.\",\n \"Title: Generalizing the Optimized Gradient Method for Smooth Convex Minimization.\\nYear: 2018\\n\\nAbstract: This paper generalizes the optimized gradient method (OGM) [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482], [D. Kim and J. A. Fessler, Math. Program., 159 (2016), pp. 81-107], [D. Kim and J. A. Fessler, J. Optim. Theory Appl., 172 (2017), pp. 187205] that achieves the optimal worst-case cost function bound of first-order methods for smooth convex minimization [Y. Drori, J. Complexity, 39 (2017), pp. 1-16]. Specifically, this paper studies a generalized formulation of OGM and analyzes its worst-case rates in terms of both the function value and the norm of the function gradient. This paper also develops a new algorithm called OGM-OG that is in the generalized family of OGM and that has the best known analytical worst-case bound with rate O(1/N-1.5) on the decrease of the gradient norm among fixed-step first-order methods. This paper also proves that Nesterov's fast gradient method [Y. Nesterov, Dokl. Akad. Nauk. USSR, 269 (1983), pp. 543-547], [Y. Nesterov, Math. Program., 103 (2005), pp. 127-152] has an O(1/N-1.5) worst-case gradient norm rate but with constant larger than OGM-OG. The proof is based on the worst-case analysis called the Performance Estimation Problem in [Y. Drori and M. Teboulle, Math. Program., 145 (2014), pp. 451-482].\",\n \"Title: Deep Dictionary-Transform Learning For Image Reconstruction\\nYear: 2018\\n\\nAbstract: Various dictionaries and transforms are known to sparsify images, and have been exploited in algorithms for image reconstruction from limited data. Methods that simultaneously reconstruct the image and learn dictionaries or sparsifying transforms for image patches, called blind compressed sensing methods, have shown promising performance. Motivated by such adaptive algorithms, this paper proposes an approach to train dictionary-transform based methods for image reconstruction by minimizing a minimum absolute reconstruction error criterion. Each \\\"layer\\\" of the algorithm consists of applying (convolving) trained transforms, thresholdings, and dictionaries to images, followed by a simple least squares update of the images. Numerical experiments illustrate the usefulness and speed-ups provided by such trained algorithms compared to related schemes.\",\n \"Title: DECT-MULTRA: Dual-Energy CT Image Decomposition With Learned Mixed Material Models and Efficient Clustering.\\nYear: 2019\\n\\nAbstract: Dual-energy computed tomography (DECT) imaging plays an important role in advanced imaging applications due to its material decomposition capability. Image-domain decomposition operates directly on CT images using linear matrix inversion, but the decomposed material images can be severely degraded by noise and artifacts. This paper proposes a new method dubbed DECT-MULTRA for image-domain DECT material decomposition that combines conventional penalized weighted-least squares (PWLS) estimation with regularization based on a mixed union of learned transforms (MULTRA) model. Our proposed approach pre-learns a union of common-material sparsifying transforms from patches extracted from all the basis materials, and a union of cross-material sparsifying transforms from multi-material patches. The common-material transforms capture the common properties among different material images, while the cross-material transforms capture the cross-dependencies. The proposed PWLS formulation is optimized efficiently by alternating between an image update step and a sparse coding and clustering step, with both of these steps having closed-form solutions. The effectiveness of our method is validated with both XCAT phantom and clinical head data. The results demonstrate that our proposed method provides superior material image quality and decomposition accuracy compared to other competing methods.\",\n \"Title: Optimizing MRF-ASL Scan Design for Precise Quantification of Brain Hemodynamics using Neural Network Regression.\\nYear: 2019\\n\\nAbstract: Purpose Arterial Spin Labeling (ASL) is a quantitative, non-invasive alternative for perfusion imaging that does not use contrast agents. The magnetic resonance fingerprinting (MRF) framework can be adapted to ASL to estimate multiple physiological parameters simultaneously. In this work, we introduce an optimization scheme to increase the sensitivity of the ASL fingerprint. We also propose a regression based estimation framework for MRF-ASL. Methods To improve the sensitivity of MRF-ASL signals to underlying parameters, we optimized ASL labeling durations using the Cramer-Rao Lower Bound (CRLB). This paper also proposes a neural network regression based estimation framework trained using noisy synthetic signals generated from our ASL signal model. We tested our methods in silico and in vivo, and compared with multiple post labeling delay (multi-PLD) ASL and unoptimized MRF-ASL. We present comparisons of estimated maps for the six parameters of our signal model. Results The scan design process facilitated precise estimates of multiple hemodynamic parameters and tissue properties from a single scan, in regions of normal gray and white matter, as well as regions with anomalous perfusion activity in the brain. In particular, there was a 86.7% correlation of perfusion estimates with the ground truth in silico, using our proposed techniques. In vivo, there was roughly a 7 fold improvement in the Coefficient of Variation (CoV) for white matter perfusion, and 2 fold improvement in gray matter perfusion CoV in comparison to a reference Multi PLD method. The regression based estimation approach provided perfusion estimates rapidly, with estimation times of around 1s per map. Conclusions Scan design optimization, coupled with regression-based estimation is a powerful tool for improving precision in MRF-ASL\",\n \"Title: Simplified Statistical Image Reconstruction for X-ray CT with Beam-Hardening Artifact Compensation.\\nYear: 2020\\n\\nAbstract: CT images are often affected by beam-hardening artifacts due to the polychromatic nature of the X-ray spectra. These artifacts appear in the image as cupping in homogeneous areas and as dark bands between dense regions such as bones. This paper proposes a simplified statistical reconstruction method for X-ray CT based on Poisson statistics that accounts for the non-linearities caused by beam hardening. The main advantages of the proposed method over previous algorithms are that it avoids the preliminary segmentation step, which can be tricky, especially for low-dose scans, and it does not require knowledge of the whole source spectrum, which is often unknown. Each voxel attenuation is modeled as a mixture of bone and soft tissue by defining density-dependent tissue fractions and maintaining one unknown per voxel. We approximate the energy-dependent attenuation corresponding to different combinations of bone and soft tissues, the so-called beam-hardening function, with the 1D function corresponding to water plus two parameters that can be tuned empirically. Results on both simulated data with Poisson sinogram noise and two rodent studies acquired with the ARGUS/CT system showed a beam hardening reduction (both cupping and dark bands) similar to analytical reconstruction followed by post-processing techniques but with reduced noise and streaks in cases with a low number of projections, as expected for statistical image reconstruction.\",\n \"Title: Improved low-count quantitative PET reconstruction with a variational neural network.\\nYear: 2019\\n\\nAbstract: Image reconstruction in low-count PET is particularly challenging because gammas from natural radioactivity in Lu-based crystals cause high random fractions that lower the measurement signal-to-noise-ratio (SNR). In model-based image reconstruction (MBIR), using more iterations of an unregularized method may increase the noise, so incorporating regularization into the image reconstruction is desirable to control the noise. New regularization methods based on learned convolutional operators are emerging in MBIR. We modify the architecture of a variational neural network, BCD-Net, for PET MBIR, and demonstrate the efficacy of the trained BCD-Net using XCAT phantom data that simulates the low true coincidence count-rates with high random fractions typical for Y-90 PET patient imaging after Y-90 microsphere radioembolization. Numerical results show that the proposed BCD-Net significantly improves PET reconstruction performance compared to MBIR methods using non-trained regularizers, total variation (TV) and non-local means (NLM), and a non-MBIR method using a single forward pass deep neural network, U-Net. BCD-Net improved activity recovery for a hot sphere significantly and reduced noise, whereas non-trained regularizers had a trade-off between noise and quantification. BCD-Net improved CNR and RMSE by 43.4% (85.7%) and 12.9% (29.1%) compared to TV (NLM) regularized MBIR. Moreover, whereas the image reconstruction results show that the non-MBIR U-Net over-fits the training data, BCD-Net successfully generalizes to data that differs from training data. Improvements were also demonstrated for the clinically relevant phantom measurement data where we used training and testing datasets having very different activity distribution and count-level.\",\n \"Title: Efficient Multi-GPU Shared Memory via Automatic Optimization of Fine-Grained Transfers\\nYear: 2021\\n\\nAbstract: Despite continuing research into inter-GPU communication mechanisms, extracting performance from multi-GPU systems remains a significant challenge. Inter-GPU communication via bulk DMA-based transfers exposes data transfer latency on the GPU’s critical execution path because these large transfers are logically interleaved between compute kernels. Conversely, fine-grained peer-to-peer memory accesses during kernel execution lead to memory stalls that can exceed the GPUs’ ability to cover these operations via multi-threading. Worse yet, these sub-cacheline transfers are highly inefficient on current inter-GPU interconnects. To remedy these issues, we propose PROACT, a system enabling remote memory transfers with the programmability and pipeline advantages of peer-to-peer stores, while achieving interconnect efficiency that rivals bulk DMA transfers. Combining compile-time instrumentation with fine-grain tracking of data block readiness within each GPU, PROACT enables interconnect-friendly data transfers while hiding the transfer latency via pipelining during kernel execution. This work describes both hardware and software implementations of PROACT and demonstrates the effectiveness of a PROACT software prototype on three generations of GPU hardware and interconnects. Achieving near-ideal interconnect efficiency, PROACT realizes a mean speedup of 3.0× over single-GPU performance for 4-GPU systems, capturing 83% of available performance opportunity. On a 16-GPU NVIDIA DGX-2 system, we demonstrate an 11.0× average strong-scaling speedup over single-GPU performance, 5.3× better than a bulk DMA-based approach.\",\n \"Title: Jigsaw: A Slice-and-Dice Approach to Non-uniform FFT Acceleration for MRI Image Reconstruction\\nYear: 2021\\n\\nAbstract: The Fast Fourier Transform (FFT) is a fundamental algorithm in signal processing; significant efforts have been made to improve its performance using software optimizations and specialized hardware accelerators. Computational imaging modalities, such as MRI, often rely on the Non-uniform Fast Fourier Transform (NuFFT), a variant of the FFT for processing data acquired from non-uniform sampling pat...\",\n \"Title: Bilevel Methods for Image Reconstruction.\\nYear: 2022\\n\\nAbstract: This review discusses methods for learning parameters for image reconstruction problems using bilevel formulations. Image reconstruction typically involves optimizing a cost function to recover a vector of unknown variables that agrees with collected measurements and prior assumptions. State-of-the-art image reconstruction methods learn these prior assumptions from training data using various machine learning techniques, such as bilevel methods. One can view the bilevel problem as formalizing hyperparameter optimization, as bridging machine learning and cost function based optimization methods, or as a method to learn variables best suited to a specific task. More formally, bilevel problems attempt to minimize an upper-level loss function, where variables in the upper-level loss function are themselves minimizers of a lower-level cost function. This review contains a running example problem of learning tuning parameters and the coefficients for sparsifying filters used in a regularizer. Such filters generalize the popular total variation regularization method, and learned filters are closely related to convolutional neural networks approaches that are rapidly gaining in popularity. Here, the lower-level problem is to reconstruct an image using a regularizer with learned sparsifying filters; the corresponding upper-level optimization problem involves a measure of reconstructed image quality based on training data. This review discusses multiple perspectives to motivate the use of bilevel methods and to make them more easily accessible to different audiences. We then turn to ways to optimize the bilevel problem, providing pros and cons of the variety of proposed approaches. Finally we overview bilevel applications in image reconstruction.\",\n \"Title: Poisson Phase Retrieval in Very Low-Count Regimes\\nYear: 2022\\n\\nAbstract: This paper proposes novel phase retrieval algorithms for maximum likelihood (ML) estimation from measurements following independent Poisson distributions in very low-count regimes, e.g., 0.25 photon per pixel. Specifically, we propose a modified Wirtinger flow (WF) algorithm using a step size based on the observed Fisher information. This approach eliminates all parameter tuning except the number of iterations. We also propose a novel curvature for majorize-minimize (MM) algorithms with a quadratic majorizer. We show theoretically that our proposed curvature is sharper than the curvature derived from the supremum of the second derivative of the Poisson ML cost function. We compare the proposed algorithms (WF, MM) with existing optimization methods, including WF using other step-size schemes, quasi-Newton methods and alternating direction method of multipliers (ADMM) algorithms, under a variety of experimental settings. Simulation experiments with a random Gaussian matrix, a canonical discrete Fourier transform (DFT) matrix, a masked DFT matrix and an empirical transmission matrix demonstrate the following. 1) As expected, algorithms based on the Poisson ML model consistently produce higher quality reconstructions than algorithms derived from Gaussian noise ML models when applied to low-count data. 2) For unregularized cases, our proposed WF algorithm with Fisher information for step size converges faster than other WF methods, e.g., WF with empirical step size, backtracking line search, and optimal step size for the Gaussian noise model; it also converges faster than the quasi-Newton method. 3) In regularized cases, our proposed WF algorithm converges faster than WF with backtracking line search, quasi-Newton, MM and ADMM.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":179,"string":"179"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":59,"string":"59"}}},{"rowIdx":60,"cells":{"question_id":{"kind":"string","value":"Abhishek Dubey"},"question":{"kind":"string","value":"Generate an abstract for the title \"URMILA: A Performance and Mobility-Aware Fog/Edge Resource Management Middleware\" using the following items: 1. Fog Computing \n2. Latency-sensitive IoT applications \n3. Resource management middleware \n4. User mobility challenges \n5. Real-world use case evaluation"},"answer":{"kind":"string","value":"Fog/'Edge computing is increasingly used to support a wide range of latency-sensitive Internet of Things (IoT) applications due to its elastic computing capabilities that are offered closer to the users. Despite this promise, IoT applications with user mobility face many challenges since offloading the application functionality from the edge to the fog may not always be feasible due to the intermittent connectivity to the fog, and could require application migration among fog nodes due to user mobility. Likewise, executing the applications exclusively on the edge may not be feasible due to resource constraints and battery drain. To address these challenges, this paper describes URMILA, a resource management middleware that makes effective tradeoffs between using fog and edge resources while ensuring that the latency requirements of the IoT applications are met. We evaluate URMILA in the context of a real-world use case on an emulated but realistic IoT testbed."},"correct_answer":{"kind":"string","value":"Fog/'Edge computing is increasingly used to support a wide range of latency-sensitive Internet of Things (IoT) applications due to its elastic computing capabilities that are offered closer to the users. Despite this promise, IoT applications with user mobility face many challenges since offloading the application functionality from the edge to the fog may not always be feasible due to the intermittent connectivity to the fog, and could require application migration among fog nodes due to user mobility. Likewise, executing the applications exclusively on the edge may not be feasible due to resource constraints and battery drain. To address these challenges, this paper describes URMILA, a resource management middleware that makes effective tradeoffs between using fog and edge resources while ensuring that the latency requirements of the IoT applications are met. We evaluate URMILA in the context of a real-world use case on an emulated but realistic IoT testbed."},"documents":{"kind":"list like","value":["Title: Integrated Monitoring and Control for Performance Management of Distributed Enterprise Systems\nYear: 2010\n\nAbstract: This paper describes an integrated monitoring and control framework for managing performance of distributed enterprise systems.","Title: Application of software health management techniques\nYear: 2011\n\nAbstract: The growing complexity of software used in large-scale, safety critical cyber-physical systems makes it increasingly difficult to expose and hence correct all potential defects. There is a need to augment the existing fault tolerance methodologies with new approaches that address latent software defects exposed at runtime. This paper describes an approach that borrows and adapts traditional 'System Health Management' techniques to improve software dependability through simple formal specification of runtime monitoring, diagnosis, and mitigation strategies. The two-level approach to health management at the component and system level is demonstrated on a simulated case study of an Air Data Inertial Reference Unit (ADIRU). An ADIRU was categorized as the primary failure source for the in-flight upset caused in the Malaysian Air flight 124 over Perth, Australia in 2005.","Title: A capacity planning process for performance assurance of component-based distributed systems (abstracts only)\nYear: 2011\n\nAbstract: For service providers of multi-tiered component-based applications, such as web portals, assuring high performance and availability to their customers without impacting revenue requires effective and careful capacity planning that aims at minimizing the number of resources, and utilizing them efficiently while simultaneously supporting a large customer base and meeting their service level agreements. This paper presents a novel, hybrid capacity planning process that results from a systematic blending of 1) analytical modeling, where traditional modeling techniques are enhanced to overcome their limitations in providing accurate performance estimates; 2) profile-based techniques, which determine performance profiles of individual software components for use in resource allocation and balancing resource usage; and 3) allocation heuristics that determine minimum number of resources to allocate software components. Our results illustrate that using our technique, performance (i.e., bounded response time) can be assured while reducing operating costs by using 25% less resources and increasing revenues by handling 20% more clients compared to traditional approaches.","Title: Efficient Autoscaling in the Cloud Using Predictive Models for Workload Forecasting\nYear: 2011\n\nAbstract: Large-scale component-based enterprise applications that leverage Cloud resources expect Quality of Service(QoS) guarantees in accordance with service level agreements between the customer and service providers. In the context of Cloud computing, auto scaling mechanisms hold the promise of assuring QoS properties to the applications while simultaneously making efficient use of resources and keeping operational costs low for the service providers. Despite the perceived advantages of auto scaling, realizing the full potential of auto scaling is hard due to multiple challenges stemming from the need to precisely estimate resource usage in the face of significant variability in client workload patterns. This paper makes three contributions to overcome the general lack of effective techniques for workload forecasting and optimal resource allocation. First, it discusses the challenges involved in auto scaling in the cloud. Second, it develops a model-predictive algorithm for workload forecasting that is used for resource auto scaling. Finally, empirical results are provided that demonstrate that resources can be allocated and deal located by our algorithm in a way that satisfies both the application QoS while keeping operational costs low.","Title: Towards a resilient deployment and configuration infrastructure for fractionated spacecraft\nYear: 2013\n\nAbstract: Fractionated spacecraft are clusters of small, independent modules that interact wirelessly to realize the functionality of a traditional monolithic spacecraft. System F6 (F6 stands for Future, Fast, Flexible, Fractionated, Free-Flying spacecraft) is a DARPA program for fractionated spacecraft. Software applications in F6 are implemented in the context of the F6 Information Architecture Platform (IAP), which provides component-based abstractions for composing distributed applications. The lifecycle of these distributed applications must be managed autonomously by a deployment and configuration (D&C) infrastructure, which can redeploy and reconfigure the running applications in response to faults and other anomalies that may occur during system operation. Addressing these D&C requirements is hard due to the significant fluctuation in resource availabilities, constraints on resources, and safety and security concerns. This paper presents the key architectural ideas that are required in realizing such a D&C infrastructure.","Title: A component model for hard real-time systems: CCM with ARINC-653\nYear: 2011\n\nAbstract: The size and complexity of software in safety-critical systems is increasing at a rapid pace. One technology that can be used to mitigate this complexity is component-based software development. However, in spite of the apparent benefits of a component-based approach to development, little work has been done in applying these concepts to hard real-time systems. This paper improves the state of the art by making three contributions: (1) we present a component model for hard real-time systems and define the semantics of different types of component interactions; (2) we present an implementation of a middleware that supports this component model. This middleware combines an open-source CORBA Component Model (CCM) implementation (MICO) with ARINC-653: a state-of-the-art real-time operating systems (RTOS) standard, (3) finally; we describe a modeling environment that enables design, analysis, and deployment of component assemblies. We conclude with a discussion of the lessons learned during this exercise. Our experiences point toward extending both the CCM as well as revising the ARINC-653. Copyright © 2011 John Wiley & Sons, Ltd.","Title: Deliberative, search-based mitigation strategies for model-based software health management\nYear: 2013\n\nAbstract: Rising software complexity in aerospace systems makes them very difficult to analyze and prepare for all possible fault scenarios at design time; therefore, classical run-time fault tolerance techniques such as self-checking pairs and triple modular redundancy are used. However, several recent incidents have made it clear that existing software fault tolerance techniques alone are not sufficient. To improve system dependability, simpler, yet formally specified and verified run-time monitoring, diagnosis, and fault mitigation capabilities are needed. Such architectures are already in use for managing the health of vehicles and systems. Software health management is the application of these techniques to software systems. In this paper, we briefly describe the software health management techniques and architecture developed by our research group. The foundation of the architecture is a real-time component framework (built upon ARINC-653 platform services) that defines a model of computation for software components. Dedicated architectural elements: the Component Level Health Manager (CLHM) and System Level Health Manager (SLHM) provide the health management services: anomaly detection, fault source isolation, and fault mitigation. The SLHM includes a diagnosis engine that (1) uses a Timed Failure Propagation Graph (TFPG) model derived from the component assembly model, (2) reasons about cascading fault effects in the system, and (3) isolates the fault source component(s). Thereafter, the appropriate system-level mitigation action is taken. The main focus of this article is the description of the fault mitigation architecture that uses goal-based deliberative reasoning to determine the best mitigation actions for recovering the system from the identified failure mode.","Title: Modeling and Analysis of Probabilistic Timed Systems\nYear: 2009\n\nAbstract: Probabilistic models are useful for analyzing systems which operate under the presence of uncertainty. In this paper, we present a technique for verifying safety and liveness properties for probabilistic timed automata. The proposed technique is an extension of a technique used to verify stochastic hybrid automata using an approximation with Markov Decision Processes. A case study for CSMA/CD protocol has been used to show case the methodology used in our technique.","Title: Compensating for Timing Jitter in Computing Systems with General-Purpose Operating Systems\nYear: 2009\n\nAbstract: Fault-tolerant frameworks for large scale computing clusters require sensor programs, which are executed periodically to facilitate performance and fault management. By construction, these clusters use general purpose operating systems such as Linux that are built for best average case performance and do not provide deterministic scheduling guarantees. Consequently, periodic applications show jitter in execution times relative to the expected execution time. Obtaining a deterministic schedule for periodic tasks in general purpose operating systems is difficult without using kernel-level modifications such as RTAI and RTLinux. However, due to performance and administrative issues kernel modification cannot be used in all scenarios. In this paper, we address the problem of jitter compensation for periodic tasks that cannot rely on modifying the operating system kernel. ; Towards that, (a) we present motivating examples; (b) we present a feedback controller based approach that runs in the user space and actively compensates periodic schedule based on past jitter; This approach is platform-agnostic i.e. it can be used in different operating systems without modification; and (c) we show through analysis and experiments that this approach is platform-agnostic i.e. it can be used in different operating systems without modification and also that it maintains a stable system with bounded total jitter.","Title: Towards a verifiable real-time, autonomic, fault mitigation framework for large scale real-time systems\nYear: 2007\n\nAbstract: Designing autonomic fault responses is difficult, particularly in large-scale systems, as there is no single ‘perfect’ fault\n mitigation response to a given failure. The design of appropriate mitigation actions depend upon the goals and state of the\n application and environment. Strict time deadlines in real-time systems further exacerbate this problem. Any autonomic behavior\n in such systems must not only be functionally correct but should also conform to properties of liveness, safety and bounded\n time responsiveness. This paper details a real-time fault-tolerant framework, which uses a reflex and healing architecture\n to provide fault mitigation capabilities for large-scale real-time systems. At the heart of this architecture is a real-time\n reflex engine, which has a state-based failure management logic that can respond to both event- and time-based triggers. We\n also present a semantic domain for verifying properties of systems, which use this framework of real-time reflex engines.\n Lastly, a case study, which examines the details of such an approach, is presented.","Title: A capacity planning process for performance assurance of component-based distributed systems\nYear: 2011\n\nAbstract: For service providers of multi-tiered component-based applications, such as web portals, assuring high performance and availability to their customers without impacting revenue requires effective and careful capacity planning that aims at minimizing the number of resources, and utilizing them efficiently while simultaneously supporting a large customer base and meeting their service level agreements. This paper presents a novel, hybrid capacity planning process that results from a systematic blending of 1) analytical modeling, where traditional modeling techniques are enhanced to overcome their limitations in providing accurate performance estimates; 2) profile-based techniques, which determine performance profiles of individual software components for use in resource allocation and balancing resource usage; and 3) allocation heuristics that determine minimum number of resources to allocate software components. Our results illustrate that using our technique, performance (i.e., bounded response time) can be assured while reducing operating costs by using 25% less resources and increasing revenues by handling 20% more clients compared to traditional approaches.","Title: Scientific Computing Autonomic Reliability Framework\nYear: 2008\n\nAbstract: Large scientific computing clusters require a distributed dependability subsystem that can provide fault isolation and recovery and is capable of learning and predicting failures, to improve the reliability of scientific workflows. In this paper, we outline the key ideas in the design of a Scientific Computing Autonomic Reliability Framework (SCARF) for large computing clusters used in the Lattice Quantum Chromo Dynamics project at Fermi Lab.","Title: Comprehensive Border Bases for Zero Dimensional Parametric Polynomial Ideals.\nYear: 2013\n\nAbstract: In this paper, we extend the idea of comprehensive Gr\\\"{o}bner bases given by Weispfenning (1992) to border bases for zero dimensional parametric polynomial ideals. For this, we introduce a notion of comprehensive border bases and border system, and prove their existence even in the cases where they do not correspond to any term order. We further present algorithms to compute comprehensive border bases and border system. Finally, we study the relation between comprehensive Gr\\\"{o}bner bases and comprehensive border bases w.r.t. a term order and give an algorithm to compute such comprehensive border bases from comprehensive Gr\\\"{o}bner bases.","Title: Algorithms for Synthesizing Safe Sets of Operation for Embedded Systems\nYear: 2009\n\nAbstract: A large number of embedded computing systems are modeled as hybrid system with both discrete and continuous dynamics. In this paper, we present algorithms for analyzing nonlinear time-invariant continuous-time systems by employing reachability algorithms. We propose synthesis algorithms for finding sets of initial states for the continuous dynamical systems so that temporal properties, such as safety and liveness properties, are satisfied. The initial sets produced by the algorithms are related to some classical concepts for continuous dynamical systems, such as invariant sets and domains of attraction.","Title: Investigating a novel GA-based feature selection method using improved KNN classifiers\nYear: 2011\n\nAbstract: This paper presents a novel scheme to select a subset of features from a dataset. We apply genetic algorithm (GA) with a random small subset of features. The GA explores stochastically a better subset of features using various combinations of lengths and features over a number of generations. The classification accuracy due to different classifiers in presence of these subsets of features is taken as the performance criteria (objective function) of GA. The proposed scheme is tested on a few UCI datasets. The performances of the KNN, informative KNN (local LI-KNN and global GI-KNN), and LI-KNN with boosting in presence of all features and those in presence of only selected subset of features are compared with reported results. With extensive simulation study, it is observed that the proposed scheme produces a reasonably good accuracy with a reduced subset of features in these datasets.","Title: Autonomic Healing of Model-Based Systems.\nYear: 2011\n\nAbstract: Embedded computing is an area in which many of the self-* properties of autonomic systems are desirable. Model-based tools for designing embedded systems, while proven successful in many applications, are not yet applicable toward building autonomic or self-sustaining embedded systems. This is, in part, due to the domain-specific nature of modeling tools used to design and deploy embedded systems. The approach outlined in this paper uses a model-driven healing process to direct the system's adaptation in such a way that the resulting system configurations satisfy their particular domain-specific needs. A method for reducing the computational complexity of this healing process is also given.","Title: Architecting Health Management into Software Component Assemblies: Lessons Learned from the ARINC-653 Component Mode\nYear: 2012\n\nAbstract: Complex real-time software systems require an active fault management capability. While testing, verification and validation schemes and their constant evolution help improve the dependability of these systems, an active fault management strategy is essential to potentially mitigate the unacceptable behaviors at run-time. In our work we have applied the experience gained from the field of Systems Health Management towards component-based software systems. The software components interact via well-defined concurrency patterns and are executed on a real-time component framework built upon ARINC-653 platform services. In this paper, we present the lessons learned in architecting and applying a two-level health management strategy to assemblies of software components.","Title: Distributed and Managed: Research Challenges and Opportunities of the Next Generation Cyber-Physical Systems\nYear: 2014\n\nAbstract: Cyber-physical systems increasingly rely on distributed computing platforms where sensing, computing, actuation, and communication resources are shared by a multitude of applications. Such 'cyber-physical cloud computing platforms' present novel challenges because the system is built from mobile embedded devices, is inherently distributed, and typically suffers from highly fluctuating connectivity among the modules. Architecting software for these systems raises many challenges not present in traditional cloud computing. Effective management of constrained resources and application isolation without adversely affecting performance are necessary. Autonomous fault management and real-time performance requirements must be met in a verifiable manner. It is also both critical and challenging to support multiple end-users whose diverse software applications have changing demands for computational and communication resources, while operating on different levels and in separate domains of security. The solution presented in this paper is based on a layered architecture consisting of a novel operating system, a middleware layer, and component-structured applications. The component model facilitates the construction of software applications from modular and reusable components that are deployed in the distributed system and interact only through well-defined mechanisms. The complexity of creating applications and performing system integration is mitigated through the use of a domain-specific model-driven development process that relies on a domain-specific modeling language and its accompanying graphical modeling tools, software generators for synthesizing infrastructure code, and the extensive use of model-based analysis for verification and validation.","Title: A Real-Time Component Framework: Experience with CCM and ARINC-653\nYear: 2010\n\nAbstract: The complexity of software in systems like aerospace vehicles has reached the point where new techniques are needed to ensure system dependability while improving the productivity of developers. One possible approach is to use precisely defined software execution platforms that (1) enable the system to be composed from separate components, (2) restrict component interactions and prevent fault propagation, and (3) whose compositional properties are well-known. In this paper we describe the initial steps towards building a platform that combines component-based software construction with hard real-time operating system services. Specifically, the paper discusses how the CORBA Component Model (CCM) could be combined with the ARINC-653 platform services and the lessons learned from this experiment. The results point towards both extending the CCM as well as revising the ARINC-653.","Title: DREMS ML: A wide spectrum architecture design language for distributed computing platforms\nYear: 2015\n\nAbstract: Complex sensing, processing and control applications running on distributed platforms are difficult to design, develop, analyze, integrate, deploy and operate, especially if resource constraints, fault tolerance and security issues are to be addressed. While technology exists today for engineering distributed, real-time component-based applications, many problems remain unsolved by existing tools. Model-driven development techniques are powerful, but there are very few existing and complete tool chains that offer an end-to-end solution to developers, from design to deployment. There is a need for an integrated model-driven development environment that addresses all phases of application lifecycle including design, development, verification, analysis, integration, deployment, operation and maintenance, with supporting automation in every phase. Arguably, a centerpiece of such a model-driven environment is the modeling language. To that end, this paper presents a wide-spectrum architecture design language called DREMS ML that itself is an integrated collection of individual domain-specific sub-languages. We claim that the language promotes “correct-by-construction” software development and integration by supporting each individual phase of the application lifecycle. Using a case study, we demonstrate how the design of DREMS ML impacts the development of embedded systems.","Title: CHARIOT: a domain specific language for extensible cyber-physical systems.\nYear: 2015\n\nAbstract: Wider adoption, availability and ubiquity of wireless networking technologies, integrated sensors, actuators, and edge computing devices is facilitating a paradigm shift by allowing us to transition from traditional statically configured vertical silos of Cyber-Physical Systems (CPS) to next generation CPS that are more open, dynamic and extensible. Fractionated spacecraft, smart cities computing architectures, Unmanned Aerial Vehicle (UAV) clusters are all examples of extensible CPS wherein extensibility is implied by the dynamic aggregation of physical resources, affect of physical dynamics on availability of computing resources, and various multi-domain applications hosted on these systems. However, realization of extensible CPS requires resolving design-time and runtime challenges emanating from properties specific to these systems. In this paper, we first describe different properties of extensible CPS - dynamism, extensibility, remote deployment, security, heterogeneity and resilience. Then we identify different design-time challenges stemming from heterogeneity and resilience requirements. We particularly focus on software heterogeneity arising from availability of various communication middleware. We then present appropriate solutions in the context of a novel domain specific language and describe how this language and its features have evolved from our past work.","Title: Analysis, verification, and management toolsuite for cyber-physical applications on time-varying networks\nYear: 2014\n\nAbstract: Cyber-Physical Systems (CPS) are increasingly utilizing advances in wireless mesh networking among computing nodes to facilitate communication and control for distributed applications. Factors such as interference or node mobility cause such wireless networks to experience changes in both topology and link capacities. These dynamic networks pose a reliability concern for high-criticality or mixed-criticality systems which require strict guarantees about system performance and robustness prior to deployment. To address the design- and run-time verification and reliability concerns created by these dynamic networks, we are developing an integrated modeling, analysis, and run-time toolsuite which provides (1) network profiles that model the dynamics of system network resources and application network requirements over time, (2) design-time verification of application performance on dynamic networks, and (3) management of the CPS network resources during run-time. In this paper we present the foundations for the analysis of dynamic networks and show experimental validations of this analysis. We conclude with a focus on future work and applications to the field.","Title: WiP Abstract: Platform for Designing and Managing Resilient and Extensible CPS\nYear: 2016\n\nAbstract: Extensible Cyber-Physical Systems (CPS) are loosely connected, multi-domain platforms that \"virtualize\" their resources to provide an open platform capable of hosting different cyber-physical applications. These cyber- physical platforms are extensible since resources and applications can be added or removed at any time. However, realizing such platform requires resolving challenges emanating from different properties; for this paper, we focus on resilience. Resilience is important for extensible CPS to make sure that extensibility of a system doesn't result in failures and anomalies.","Title: Poster Abstract: Distributed Reasoning for Diagnosing Cascading Outages in Cyber Physical Energy Systems\nYear: 2016\n\nAbstract: The power grid incorporates a number of protection elements such as distance relays that detect faults and prevent the propagation of failure effects from influencing the rest of system. However, the decision of these protection elements is only influenced by local information in the form of bus voltage/current (V-I) samples. Due to lack of system wide perspective, erroneous settings, and latent failure modes, protection devices often mis-operate and cause cascading effects that ultimately lead to blackouts. Blackouts around the world have been triggered or worsened by circuit breakers tripping, including the blackout of 2003 in North America, where the secondary/ remote protection relays incorrectly opened the breaker. Tools that aid the operators in finding the root cause of the problem on-line are required. However, high system complexity and the interdependencies between the cyber and physical elements of the system and the mis-operation of protection devices make the failure diagnosis a challenging problem.","Title: Designing a Resilient Deployment and Reconfiguration Infrastructure for Remotely Managed Cyber-Physical Systems.\nYear: 2016\n\nAbstract: Multi-module Cyber-Physical Systems (CPS), such as satellite clusters, swarms of Unmanned Aerial Vehicles (UAV), and fleets of Unmanned Underwater Vehicles (UUV) provide a CPS cluster-as-a- service for CPS applications. The distributed and remote nature of these systems often necessitates the use of Deployment and Configuration (D&C) services to manage the lifecycle of these applications. Fluctuating resources, volatile cluster membership and changing environmental conditions necessitate resilience. Thus, the D&C infrastructure does not only have to undertake basic management actions, such as activation of new applications and deactivation of existing applications, but also has to autonomously reconfigure existing applications to mitigate failures including D&C infrastructure failures. This paper describes the design and architectural considerations to realize such a D&C infrastructure for component-based distributed systems. Experimental results demonstrating the autonomous resilience capabilities are presented.","Title: The Role of Context and Resilient Middleware in Next Generation Smart Grids.\nYear: 2016\n\nAbstract: The emerging trends of volatile distributed energy resources and micro-grids are putting pressure on electrical power system infrastructure. This pressure is motivating the integration of digital technology and advanced power-industry practices to improve the management of distributed electricity generation, transmission, and distribution, thereby creating a web of systems. Unlike legacy power system infrastructure, however, this emerging next-generation smart grid should be context-aware and adaptive to enable the creation of applications needed to enhance grid robustness and efficiency. This paper describes key factors that are driving the architecture of smart grids and describes orchestration middleware needed to make the infrastructure resilient. We use an example of adaptive protection logic in smart grid substations as a use case to motivate the need for contextawareness and adaptivity.","Title: Delayradar: A Multivariate Predictive Model For Transit Systems\nYear: 2016\n\nAbstract: Effective public transit operations are one of the fundamental requirements for a modern community. Recently, a number of transit agencies have started integrating automated vehicle locators in their fleet, which provides a real-time estimate of the time of arrival. In this paper, we use the data collected over several months from one such transit system and show how this data can be potentially used to learn long term patterns of travel time. More specifically, we study the effect of weather and other factors such as traffic on the transit system delay. These models can later be used to understand the seasonal variations and to design adaptive and transient transit schedules. Towards this goal, we also propose an online architecture called DelayRadar. The novelty of DelayRadar lies in three aspects: (1) a data store that collects and integrates real-time and static data from multiple data sources, (2) a predictive statistical model that analyzes the data to make predictions on transit travel time, and (3) a decision making framework to develop an optimal transit schedule based on variable forecasts related to traffic, weather, and other impactful factors. This paper focuses on identifying the model with the best predictive accuracy to be used in DelayRadar. According to the preliminary study results, we are able to explain more than 70% of the variance in the bus travel time and we can make future travel predictions with an out-of-sample error of 4.8 minutes with information on the bus schedule, traffic, and weather.","Title: Achieving resilience in distributed software systems via self-reconfiguration.\nYear: 2016\n\nAbstract: We describe resilient operation of cyber-physical application platforms.We describe implicit design-time encoding of the reconfiguration.We describe design-time analysis and validation tools for these systems. Improvements in mobile networking combined with the ubiquitous availability and adoption of low-cost development boards have enabled the vision of mobile platforms of Cyber-Physical Systems (CPS), such as fractionated spacecraft and UAV swarms. Computation and communication resources, sensors, and actuators that are shared among different applications characterize these systems. The cyber-physical nature of these systems means that physical environments can affect both the resource availability and software applications that depend on resource availability. While many application development and management challenges associated with such systems have been described in existing literature, resilient operation and execution have received less attention. This paper describes our work on improving runtime support for resilience in mobile CPS, with a special focus on our runtime infrastructure that provides autonomous resilience via self-reconfiguration. We also describe the interplay between this runtime infrastructure and our design-time tools, as the later is used to statically determine the resilience properties of the former. Finally, we present a use case study to demonstrate and evaluate our design-time resilience analysis and runtime self-reconfiguration infrastructure.","Title: Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems.\nYear: 2016\n\nAbstract: In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems.","Title: Optimal Detection of Faulty Traffic Sensors Used in Route Planning.\nYear: 2017\n\nAbstract: In a smart city, real-time traffic sensors may be deployed for various applications, such as route planning. Unfortunately, sensors are prone to failures, which result in erroneous traffic data. Erroneous data can adversely affect applications such as route planning, and can cause increased travel time. To minimize the impact of sensor failures, we must detect them promptly and accurately. However, typical detection algorithms may lead to a large number of false positives (i.e., false alarms) and false negatives (i.e., missed detections), which can result in suboptimal route planning. In this paper, we devise an effective detector for identifying faulty traffic sensors using a prediction model based on Gaussian Processes. Further, we present an approach for computing the optimal parameters of the detector which minimize losses due to false-positive and false-negative errors. We also characterize critical sensors, whose failure can have high impact on the route planning application. Finally, we implement our method and evaluate it numerically using a real- world dataset and the route planning platform OpenTripPlanner.","Title: Poster Abstract: A Distributed and Resilient Platform for City-Scale Smart Systems\nYear: 2016\n\nAbstract: The advent of the Internet of Things (IoT) is driving several technological trends. The first trend is an increased level of integration between edge devices and commodity computers. This trend, in conjunction with low power-devices, energy harvesting, and improved battery technology, is enabling the next generation of information technology (IT) innovation: city-scale smart systems. These types of IoT systems can operate at multiple time-scales, ranging from closed-loop control requiring strict real-time decision and actuation to near real-time operation with humans-in-the-loop, as well as to long-term analysis, planning, and decision-making.","Title: Demo Abstract: RIAPS — A Resilient Information Architecture Platform for Edge Computing\nYear: 2016\n\nAbstract: The emerging CPS/IoT ecosystem platforms such as Beaglebone Black, Raspberry Pi, Intel Edison and other edge devices such as SCALE, Paradrop are providing new capabilities for data collection, analysis and processing at the edge (also referred to as Fog Computing). This allows the dynamic composition of computing and communication networks that can be used to monitor and control the physical phenomena closer to the physical system. However, there are still a number of challenges that exist and must be resolved before we see wider applicability of these platforms for applications in safety-critical application domains such as Smart Grid and Traffic Control.","Title: Resilience at the edge in cyber-physical systems\nYear: 2017\n\nAbstract: As the number of low cost computing devices at the edge of communication network increase, there are greater opportunities to enable innovative capabilities, especially in cyber-physical systems. For example, micro-grid power systems can make use of computing capabilities at the edge of a Smart Grid to provide more robust and decentralized control. However, the downside to distributing intelligence to the edge away from the controlled environment of the data centers is the increased risk of failures. The paper introduces a framework for handling these challenges. The contribution of this framework is to support strategies to (a) tolerate the transient faults as they appear due to network fluctuations or node failures, and to (b) systematically reconfigure the application if the faults persist.","Title: Prioritized Allocation of Emergency Responders based on a Continuous-Time Incident Prediction Model.\nYear: 2017\n\nAbstract: Efficient emergency response is a major concern in densely populated urban areas. Numerous techniques have been proposed to allocate emergency responders to optimize response times, coverage, and incident prevention. Effective response depends, in turn, on effective prediction of incidents occurring in space and time, a problem which has also received considerable prior attention. We formulate a non-linear mathematical program maximizing expected incident coverage, and propose a novel algorithmic framework for solving this problem. In order to aid the optimization problem, we propose a novel incident prediction mechanism. Prior art in incident prediction does not generally consider incident priorities which are crucial in optimal dispatch, and spatial modeling either considers each discretized area independently, or learns a homogeneous model. We bridge these gaps by learning a joint distribution of both incident arrival time and severity, with spatial heterogeneity captured using a hierarchical clustering approach. Moreover, our decomposition of the joint arrival and severity distributions allows us to independently learn the continuous-time arrival model, and subsequently use a multinomial logistic regression to capture severity, conditional on incident time. We use real traffic accident and response data from the urban area around Nashville, USA, to evaluate the proposed approach, showing that it significantly outperforms prior art as well as the real dispatch method currently in use.","Title: RIAPS: Resilient Information Architecture Platform for Decentralized Smart Systems\nYear: 2017\n\nAbstract: The emerging Fog Computing paradigm provides an additional computational layer that enables new capabilities in real-time data-driven applications. This is especially interesting in the domain of Smart Grid as the boundaries between traditional generation, distribution, and consumer roles are blurring. This is a reflection of the ongoing trend of intelligence distribution in Smart Systems. In this paper, we briefly describe a component-based decentralized software platform called Resilient Information Architecture Platform for Smart Systems (RIAPS) which provides an infrastructure for such systems. We briefly describe some initial applications built using this platform. Then, we focus on the design and integration choices for a resilient Discovery Manager service that is a critical component of this infrastructure. The service allows applications to discover each other, work collaboratively, and ensure the stability of the Smart System.","Title: Short Paper: Towards Low-Cost Indoor Localization Using Edge Computing Resources\nYear: 2017\n\nAbstract: Emerging smart services, such as indoor smart parking or patient monitoring and tracking in hospitals, incur a significant technical roadblock stemming primarily from a lack of cost-effective and easily deployable localization framework that impedes their widespread deployment. To address this concern, in this paper we present a low-cost, indoor localization and navigation system, which performs continuous and real-time processing of Bluetooth Low Energy (BLE) and IEEE 802.15.4a compliant Ultra-wideband (UWB) sensor data to localize and navigate the concerned entity to its desired location. Our approach depends upon fusing the two feature sets, using the UWB to calibrate the BLE localization mechanism.","Title: SpeedPro: A Predictive Multi-Model Approach for Urban Traffic Speed Estimation\nYear: 2017\n\nAbstract: Data generated by GPS-equipped probe vehicles, especially public transit vehicles can be a reliable source for traffic speed estimation. Traditionally, this estimation is done by learning the parameters of a model that describes the relationship between the speed of the probe vehicle and the actual traffic speed. However, such approaches typically suffer from data sparsity issues. Furthermore, most state of the art approaches does not consider the effect of weather and the driver of the probe vehicle on the parameters of the learned model. In this paper, we describe a multivariate predictive multi-model approach called SpeedPro that (a) first identifies similar clusters of operation from the historic data that includes the real-time position of the probe vehicle, the weather data, and anonymized driver identifier, and then (b) uses these different models to estimate the traffic speed in real-time as a function of current weather, driver and probe vehicle speed. When the real-time information is not available our approach uses a different model that uses the historical weather and traffic information for estimation. Our results show that the purely historical data is less accurate than the model that uses the real-time information.","Title: Unsupervised Mechanisms For Optimizing On-Time Performance Of Fixed Schedule Transit Vehicles\nYear: 2017\n\nAbstract: The on-time arrival performance of vehicles at stops is a critical metric for both riders and city planners to evaluate the reliability of a transit system. However, it is a non-trivial task for transit agencies to adjust the existing bus schedule to optimize the on-time performance for the future. For example, severe weather conditions and special events in the city could slow down traffic and cause bus delay. Furthermore, the delay of previous trips may affect the initial departure time of consecutive trips and generate accumulated delay. In this paper, we formulate the problem as a single-objective optimization task with constraints and propose a greedy algorithm and a genetic algorithm to generate bus schedules at timepoints that improve the bus on-time performance at timepoints which is indicated by whether the arrival delay is within the desired range. We use the Nashville bus system as a case study and simulate the optimization performance using historical data. The comparative analysis of the results identifies that delay patterns change over time and reveals the efficiency of the greedy and genetic algorithms.","Title: Indicator frameworks.\nYear: 2017\n\nAbstract: We develop a diagrammatic tool for constructing correlations between random variables, called an abstract indicator framework. Abstract indicator frameworks are modeled off operational (key performance) indicator frameworks as they are used in city planning and project governance, and give a rigorous, statistically-motivated process for constructing operational indicator frameworks.","Title: Transactive energy demo with RIAPS platform.\nYear: 2017\n\nAbstract: This work presents a platform for decentralized distributed computing called Resilient Information Architecture for the Smart Grid (RIAPS) through a transactional energy and a traffic application.","Title: Diagnostics and prognostics using temporal causal models for cyber physical energy systems.\nYear: 2017\n\nAbstract: Reliable operation of cyber-physical systems such as Power Transmission and Distribution Systems is critical for the seamless functioning of a vibrant economy. These systems consist of tightly coupled physical (energy sources, transmission and distribution lines, and loads) and computational components (protection devices, energy management systems, etc). The protection devices such as distance relays help in preventing failure propagation by isolating faulty physical components. However, these devices rely on hard thresholds and local information, often ignoring system-level effects introduced by the distributed control algorithms. This leads to scenarios wherein a local mitigation in a subsystem could trigger a larger fault cascade, possibly resulting in a blackout. Efficient models and tool that curtail such systematic failures by performing fault diagnosis and prognosis are therefore necessary.","Title: A Systematic Approach of Identifying Optimal Load Control Actions for Arresting Cascading Failures in Power Systems\nYear: 2017\n\nAbstract: Cascading outages in power networks cause blackouts which lead to huge economic and social consequences. The traditional form of load shedding is avoidable in many cases by identifying optimal load control actions. However, if there is a change in the system topology (adding or removing loads, lines etc), the calculations have to be performed again. This paper addresses this problem by providing a workflow that 1) generates system models from IEEE CDF specifications, 2) identifies a collection of blackout causing contingencies, 3) dynamically sets up an optimization problem, and 4) generates a table of mitigation strategies in terms of minimal load curtailment. We demonstrate the applicability of our proposed methodology by finding load curtailment actions for N-k contingencies (k = 1, 2, 3) in IEEE 14 Bus system.","Title: On the Design of Communication and Transaction Anonymity in Blockchain-Based Transactive Microgrids.\nYear: 2017\n\nAbstract: Transactive microgrids are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation, such as wind and solar power. Distributed ledgers have recently found widespread interest in this domain due to their ability to provide transactional integrity across decentralized computing nodes. However, the existing state of the art has not focused on the privacy preservation requirement of these energy systems - the transaction level data can provide much greater insights into a prosumer's behavior compared to smart meter data. There are specific safety requirements in transactive microgrids to ensure the stability of the grid and to control the load. To fulfil these requirements, the distribution system operator needs transaction information from the grid, which poses a further challenge to the privacy goals. In this paper, we extend a recently developed trading workflow called PETra and describe our solution for communication and transactional anonymity.","Title: Providing Privacy, Safety, and Security in IoT-Based Transactive Energy Systems using Distributed Ledgers.\nYear: 2017\n\nAbstract: Power grids are undergoing major changes due to rapid growth in renewable energy resources and improvements in battery technology. While these changes enhance sustainability and efficiency, they also create significant management challenges as the complexity of power systems increases. To tackle these challenges, decentralized Internet-of-Things (IoT) solutions are emerging, which arrange local communities into transactive microgrids. Within a transactive microgrid, prosumers (i.e., consumers with energy generation and storage capabilities) can trade energy with each other, thereby smoothing the load on the main grid using local supply. It is hard, however, to provide security, safety, and privacy in a decentralized and transactive energy system. On the one hand, prosumersu0027 personal information must be protected from their trade partners and the system operator. On the other hand, the system must be protected from careless or malicious trading, which could destabilize the entire grid. This paper describes Privacy-preserving Energy Transactions (PETra), which is a secure and safe solution for transactive microgrids that enables consumers to trade energy without sacrificing their privacy. PETra builds on distributed ledgers, such as blockchains, and provides anonymity for communication, bidding, and trading.","Title: Privacy-Preserving Platform for Transactive Energy Systems.\nYear: 2017\n\nAbstract: Transactive energy systems (TES) are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation. These, on one hand, pose a decentralized power system controls problem, requiring strategic microgrid control to maintain stability for the community and for the utility. On the other hand, they require robust financial markets operating on distributed software platforms that preserve privacy. In this paper, we describe the implementation of a novel, blockchain-based transactive energy system. We outline the key requirements and motivation of this platform, describe the lessons learned, and provide a description of key architectural components of this system.","Title: DREMS-OS: An Operating System for Managed Distributed Real-Time Embedded Systems\nYear: 2017\n\nAbstract: Distributed real-time and embedded (DRE) systems executing mixed criticality task sets are increasingly being deployed in mobile and embedded cloud computing platforms, including space applications. These DRE systems must not only operate over a range of temporal and spatial scales, but also require stringent assurances for secure interactions between the system's tasks without violating their individual timing constraints. To address these challenges, this paper describes a novel distributed operating system focusing on the scheduler design to support the mixed criticality task sets. Empirical results from experiments involving a case study of a cluster of satellites emulated in a laboratory testbed validate our claims.","Title: Time synchronization services for low-cost fog computing applications.\nYear: 2017\n\nAbstract: This paper presents the time synchronization infrastructure for a low-cost run-time platform and application framework specifically targeting Smart Grid applications. Such distributed applications require the execution of reliable and accurate time-coordinated actions and observations both within islands of deployments and across geographically distant nodes. The time synchronization infrastructure is built on well-established technologies: GPS, NTP, PTP, PPS and Linux with real-time extensions, running on low-cost BeagleBone Black hardware nodes. We describe the architecture, implementation, instrumentation approach, performance results and present an example from the application domain. Also, we discuss an important finding on the effect of the Linux RT_PREEMPT real-time patch on the accuracy of the PPS subsystem and its use for GPS-based time references.","Title: Towards a Socially Optimal Multi-Modal Routing Platform.\nYear: 2018\n\nAbstract: The increasing rate of urbanization has added pressure on the already constrained transportation networks in our communities. Ride-sharing platforms such as Uber and Lyft are becoming a more commonplace, particularly in urban environments. While such services may be deemed more convenient than riding public transit due to their on-demand nature, reports show that they do not necessarily decrease the congestion in major cities. One of the key problems is that typically mobility decision support systems focus on individual utility and react only after congestion appears. In this paper, we propose socially considerate multi-modal routing algorithms that are proactive and consider, via predictions, the shared effect of riders on the overall efficacy of mobility services. We have adapted the MATSim simulator framework to incorporate the proposed algorithms present a simulation analysis of a case study in Nashville, Tennessee that assesses the effects of our routing models on the traffic congestion for different levels of penetration and adoption of socially considerate routes. Our results indicate that even at a low penetration (social ratio), we are able to achieve an improvement in system-level performance.","Title: SolidWorx: A Resilient and Trustworthy Transactive Platform for Smart and Connected Communities.\nYear: 2018\n\nAbstract: Internet of Things and data sciences are fueling the development of innovative solutions for various applications in Smart and Connected Communities (SCC). These applications provide participants with the capability to exchange not only data but also resources, which raises the concerns of integrity, trust, and above all the need for fair and optimal solutions to the problem of resource allocation. This exchange of information and resources leads to a problem where the stakeholders of the system may have limited trust in each other. Thus, collaboratively reaching consensus on when, how, and who should access certain resources becomes problematic. This paper presents SolidWorx, a blockchain-based platform that provides key mechanisms required for arbitrating resource consumption across different SCC applications in a domain-agnostic manner. For example, it introduces and implements a hybrid-solver pattern, where complex optimization computation is handled off-blockchain while solution validation is performed by a smart contract. To ensure correctness, the smart contract of SolidWorx is generated and verified using a model-based approach.","Title: Towards an architecture for evaluating and analyzing decentralized Fog applications\nYear: 2017\n\nAbstract: As the number of low cost computing devices at the edge of network increases, there are greater opportunities to enable novel, innovative capabilities, especially in decentralized cyber-physical systems. For example, in an urban setting, a set of networked, collaborating processors at the edge can be used to dynamically detect traffic densities via image processing and then use those densities to control the traffic flow by coordinating traffic light sequences, in a decentralized architecture. In this paper we describe a testbed and an application framework for such applications.","Title: Performance evaluation of smart systems under uncertainty\nYear: 2017\n\nAbstract: This paper develops a model-based framework for the quantification and propagation of multiple uncertainty sources affecting the performance of a smart system. A smart system, in general, performs sensing, control and actuation for proper functioning of a physical subsystem (also referred to as a plant). With strong feedback coupling between several subsystems, the uncertainty in the quantities of interest (QoI) amplifies over time. The coupling in a generic smart system occurs at two levels: (1) coupling between individual subsystems (plant, cyber, actuation, sensors), and (2) coupling between nodes in a distributed computational subsystem. In this paper, a coupled smart system is decoupled and considered as a feed-forward system over time and modeled using a two-level Dynamic Bayesian Network (DBN), one at each level of coupling (between subsystems and between nodes). A DBN can aggregate uncertainty from multiple sources within a time step and across time steps. The DBN associated with a smart system can be learned using available system models, physics models and data. The proposed methodology is demonstrated for the design of a smart indoor heating system (identification of sensors and a wireless network) within cost constraints that enables room-by-room temperature control. We observe that sensor uncertainty has a higher impact on the performance of the heating system compared to the uncertainty in the wireless network.","Title: Mobilytics- An Extensible, Modular and Resilient Mobility Platform\nYear: 2018\n\nAbstract: Transportation management platforms provide communities the ability to integrate the available mobility options and localized transportation demand management policies. A central component of a transportation management platform is the mobility planning application. Given the societal relevance of these platforms, it is necessary to ensure that they operate resiliently. Modularity and extensibility are also critical properties that are required for manageability. Modularity allows to isolate faults easily. Extensibility enables update of policies and integration of new mobility modes or new routing algorithms. However, state of the art mobility planning applications like open trip planner, are monolithic applications, which makes it difficult to scale and modify them dynamically. This paper describes a microservices based modular multi-modal mobility platform Mobilytics, that integrates mobility providers, commuters, and community stakeholders. We describe our requirements, architecture, and discuss the resilience challenges, and how our platform functions properly in presence of failure. Conceivably, the patterns and principles manifested in our system can serve as guidelines for current and future practitioners in this field.","Title: Short-Term Transit Decision Support System Using Multi-task Deep Neural Networks\nYear: 2018\n\nAbstract: Unpredictability is one of the top reasons that prevent people from using public transportation. To improve the on-time performance of transit systems, prior work focuses on updating schedule periodically in the long-term and providing arrival delay prediction in real-time. But when no real-time transit and traffic feed is available (e.g., one day ahead), there is a lack of effective contextual prediction mechanism that can give alerts of possible delay to commuters. In this paper, we propose a generic tool-chain that takes standard General Transit Feed Specification (GTFS) transit feeds and contextual information (recurring delay patterns before and after big events in the city and the contextual information such as scheduled events and forecasted weather conditions) as inputs and provides service alerts as output. Particularly, we utilize shared route segment networks and multi-task deep neural networks to solve the data sparsity and generalization issues. Experimental evaluation shows that the proposed toolchain is effective at predicting severe delay with a relatively high recall of 76% and F1 score of 55%.","Title: CHARIOT: Goal-Driven Orchestration Middleware for Resilient IoT Systems.\nYear: 2018\n\nAbstract: An emerging trend in Internet of Things (IoT) applications is to move the computation (cyber) closer to the source of the data (physical). This paradigm is often referred to as edge computing. If edge resources are pooled together, they can be used as decentralized shared resources for IoT applications, providing increased capacity to scale up computations and minimize end-to-end latency. Managing applications on these edge resources is hard, however, due to their remote, distributed, and (possibly) dynamic nature, which necessitates autonomous management mechanisms that facilitate application deployment, failure avoidance, failure management, and incremental updates. To address these needs, we present CHARIOT, which is orchestration middleware capable of autonomously managing IoT systems consisting of edge resources and applications.\n\nCHARIOT implements a three-layer architecture. The topmost layer comprises a system description language, the middle layer comprises a persistent data storage layer and the corresponding schema to store system information, and the bottom layer comprises a management engine that uses information stored persistently to formulate constraints that encode system properties and requirements, thereby enabling the use of satisfiability modulo theory solvers to compute optimal system (re)configurations dynamically at runtime. This article describes the structure and functionality of CHARIOT and evaluates its efficacy as the basis for a smart parking system case study that uses sensors to manage parking spaces.","Title: A Data-driven Prognostic Architecture for Online Monitoring of Hard Disks Using Deep LSTM Networks.\nYear: 2018\n\nAbstract: With the advent of pervasive cloud computing technologies, service reliability and availability are becoming major concerns,especially as we start to integrate cyber-physical systems with the cloud networks. A number of smart and connected community systems such as emergency response systems utilize cloud networks to analyze real-time data streams and provide context-sensitive decision support.Improving overall system reliability requires us to study all the aspects of the end-to-end of this distributed system,including the backend data servers. In this paper, we describe a bi-layered prognostic architecture for predicting the Remaining Useful Life (RUL) of components of backend servers,especially those that are subjected to degradation. We show that our architecture is especially good at predicting the remaining useful life of hard disks. A Deep LSTM Network is used as the backbone of this fast, data-driven decision framework and dynamically captures the pattern of the incoming data. In the article, we discuss the architecture of the neural network and describe the mechanisms to choose the various hyper-parameters. We describe the challenges faced in extracting effective training sets from highly unorganized and class-imbalanced big data and establish methods for online predictions with extensive data pre-processing, feature extraction and validation through test sets with unknown remaining useful lives of the hard disks. Our algorithm performs especially well in predicting RUL near the critical zone of a device approaching failure.The proposed architecture is able to predict whether a disk is going to fail in next ten days with an average precision of 0.8435.In future, we will extend this architecture to learn and predict the RUL of the edge devices in the end-to-end distributed systems of smart communities, taking into consideration context-sensitive external features such as weather.","Title: Introducing the new paradigm of Social Dispersed Computing: Applications, Technologies and Challenges.\nYear: 2018\n\nAbstract: If last decade viewed computational services as a utilitythen surely this decade has transformed computation into a commodity. Computation is now progressively integrated into the physical networks in a seamless way that enables cyber-physical systems (CPS) and the Internet of Things (IoT) meet their latency requirements. Similar to the concept of “platform as a service” or “software as a service”, both cloudlets and fog computing have found their own use cases. Edge devices (that we call end or user devices for disambiguation) play the role of personal computers, dedicated to a user and to a set of correlated applications. In this new scenario, the boundaries between the network node, the sensor, and the actuator are blurring, driven primarily by the computation power of IoT nodes like single board computers and the smartphones. The bigger data generated in this type of networks needs clever, scalable, and possibly decentralized computing solutions that can scale independently as required. Any node can be seen as part of a graph, with the capacity to serve as a computing or network router node, or both. Complex applications can possibly be distributed over this graph or network of nodes to improve the overall performance like the amount of data processed over time. In this paper, we identify this new computing paradigm that we call Social Dispersed Computing, analyzing key themes in it that includes a new outlook on its relation to agent based applications. We architect this new paradigm by providing supportive application examples that include next generation electrical energy distribution networks, next generation mobility services for transportation, and applications for distributed analysis and identification of non-recurring traffic congestion in cities. The paper analyzes the existing computing paradigms (e.g., cloud, fog, edge, mobile edge, social, etc.), solving the ambiguity of their definitions; and analyzes and discusses the relevant foundational software technologies, the remaining challenges, and research opportunities.","Title: VeriSolid: Correct-by-Design Smart Contracts for Ethereum.\nYear: 2019\n\nAbstract: The adoption of blockchain based distributed ledgers is growing fast due to their ability to provide reliability, integrity, and auditability without trusted entities. One of the key capabilities of these emerging platforms is the ability to create self-enforcing smart contracts. However, the development of smart contracts has proven to be error-prone in practice, and as a result, contracts deployed on public platforms are often riddled with security vulnerabilities. This issue is exacerbated by the design of these platforms, which forbids updating contract code and rolling back malicious transactions. In light of this, it is crucial to ensure that a smart contract is secure before deploying it and trusting it with significant amounts of cryptocurrency. To this end, we introduce the VeriSolid framework for the formal verification of contracts that are specified using a transition-system based model with rigorous operational semantics. Our model-based approach allows developers to reason about and verify contract behavior at a high level of abstraction. VeriSolid allows the generation of Solidity code from the verified models, which enables the correct-by-design development of smart contracts.","Title: TRANSAX: A Blockchain-Based Decentralized Forward-Trading Energy Exchanged for Transactive Microgrids\nYear: 2019\n\nAbstract: Power grids are undergoing major changes due to rapid growth in renewable energy and improvements in battery technology. Prompted by the increasing complexity of power systems, decentralized IoT solutions are emerging, which arrange local communities into transactive microgrids. The core functionality of these solutions is to provide mechanisms for matching producers with consumers while ensuring system safety. However, there are multiple challenges that these solutions still face: privacy, trust, and resilience. The privacy challenge arises because the time series of production and consumption data for each participant is sensitive and may be used to infer personal information. Trust is an issue because a producer or consumer can renege on the promised energy transfer. Providing resilience is challenging due to the possibility of failures in the infrastructure that is required to support these market based solutions. In this paper, we develop a rigorous solution for transactive microgrids that addresses all three challenges by providing an innovative combination of MILP solvers, smart contracts, and publish-subscribe middleware within a framework of a novel distributed application platform, called Resilient Information Architecture Platform for Smart Grid. Towards this purpose, we describe the key architectural concepts, including fault tolerance, and show the trade-off between market efficiency and resource requirements,","Title: Incident Analysis And Prediction Using Clustering And Bayesian Network\nYear: 2017\n\nAbstract: Advances in data collection and storage infrastructure offer an unprecedented opportunity to integrate both data and emergency resources in a city into a dynamic learning system that can anticipate and rapidly respond to heterogeneous incidents. In this paper, we describe integration methods for spatio-temporal incident forecasting using previously collected vehicular accident data provided to us by the Nashville Fire Department. The literature provides several techniques that focus on analyzing features and predicting accidents for specific situations (specific intersections in a city, or certain segments of a freeway, for example), but these models break down when applied to a large, general area consisting of many road and intersection types and other factors like weather conditions. We use Similarity Based Agglomerative Clustering (SBAC) analysis to categorize incidents to account for these variables. Thereafter, we use survival analysis to learn the likelihood of incidents per cluster. The mapping of the clusters to the spatial locations is achieved using a Bayesian network. The prediction methods we have developed lay the foundation for future work on an optimal emergency vehicle allocation and dispatch system in Nashville.","Title: PlaTIBART: a platform for transactive IoT blockchain applications with repeatable testing.\nYear: 2017\n\nAbstract: With the advent of blockchain-enabled IoT applications, there is an increased need for related software patterns, middleware concepts, and testing practices to ensure adequate quality and productivity. IoT and blockchain each provide different design goals, concepts, and practices that must be integrated, including the distributed actor model and fault tolerance from IoT and transactive information integrity over untrustworthy sources from blockchain. Both IoT and blockchain are emerging technologies and both lack codified patterns and practices for development of applications when combined. This paper describes PlaTIBART, which is a platform for transactive IoT blockchain applications with repeatable testing that combines the Actor pattern (which is a commonly used model of computation in IoT) together with a custom Domain Specific Language (DSL) and test network management tools. We show how PlaTIBART has been applied to develop, test, and analyze fault-tolerant IoT blockchain applications.","Title: Transit-hub: a smart public transportation decision support system with multi-timescale analytical services\nYear: 2019\n\nAbstract: Public transit is a critical component of a smart and connected community. As such, citizens expect and require accurate information about real-time arrival/departures of transportation assets. As transit agencies enable large-scale integration of real-time sensors and support back-end data-driven decision support systems, the dynamic data-driven applications systems (DDDAS) paradigm becomes a promising approach to make the system smarter by providing online model learning and multi-time scale analytics as part of the decision support system that is used in the DDDAS feedback loop. In this paper, we describe a system in use in Nashville and illustrate the analytic methods developed by our team. These methods use both historical as well as real-time streaming data for online bus arrival prediction. The historical data is used to build classifiers that enable us to create expected performance models as well as identify anomalies. These classifiers can be used to provide schedule adjustment feedback to the metro transit authority. We also show how these analytics services can be packaged into modular, distributed and resilient micro-services that can be deployed on both cloud back ends as well as edge computing resources.","Title: Device Access Abstractions for Resilient Information Architecture Platform for Smart Grid\nYear: 2019\n\nAbstract: This letter presents an overview of design mechanisms to abstract device access protocols in the resilient information architecture platform for smart grid, a middleware for developing distributed smart grid applications. These mechanisms are required to decouple the application functionality from the specifics of the device mechanisms built by the device vendors.","Title: Supporting Fog/Edge-Based Cognitive Assistance Iot Services For The Visually Mpaired\nYear: 2019\n\nAbstract: The fog/edge computing paradigm is increasingly being adopted to support a variety of latency-sensitive IoT services, such as cognitive assistance to the visually impaired, due to its ability to assure the latency requirements of these services while continuing to benefit from the elastic properties of cloud computing. However, user mobility in such applications imposes a new set of challenges that must be addressed before such applications can be deployed and benefit the society. This paper presents ongoing work on a dynamic resource management middleware called URMILA that addresses these concerns. URMILA ensures that the service remains available despite user mobility and ensuing wireless connectivity issues by opportunistically leveraging both fog and edge resources in such a way that the latency requirements of the service are met while ensuring longevity of the battery life on the edge devices. We present the design principles of URMILA's capabilities and a real-world cognitive assistance application that we have built and are testing on an emulated but realistic IoT testbed.","Title: An online decision-theoretic pipeline for responder dispatch.\nYear: 2019\n\nAbstract: The problem of dispatching emergency responders to service traffic accidents, fire, distress calls and crimes plagues urban areas across the globe. While such problems have been extensively looked at, most approaches are offline. Such methodologies fail to capture the dynamically changing environments under which critical emergency response occurs, and therefore, fail to be implemented in practice. Any holistic approach towards creating a pipeline for effective emergency response must also look at other challenges that it subsumes - predicting when and where incidents happen and understanding the changing environmental dynamics. We describe a system that collectively deals with all these problems in an online manner, meaning that the models get updated with streaming data sources. We highlight why such an approach is crucial to the effectiveness of emergency response, and present an algorithmic framework that can compute promising actions for a given decision-theoretic model for responder dispatch. We argue that carefully crafted heuristic measures can balance the trade-off between computational time and the quality of solutions achieved and highlight why such an approach is more scalable and tractable than traditional approaches. We also present an online mechanism for incident prediction, as well as an approach based on recurrent neural networks for learning and predicting environmental features that affect responder dispatch. We compare our methodology with prior state-of-the-art and existing dispatch strategies in the field, which show that our approach results in a reduction in response time with a drastic reduction in computational time.","Title: Incident management and analysis dashboard for fire departments - ICCPS demo.\nYear: 2019\n\nAbstract: This work presents a dashboard tool that helps emergency responders analyze and manage spatial-temporal incidents like crime and traffic accidents. It uses state-of-the-art statistical models to learn incident probabilities based on factors such as prior incidents, time and weather. The dashboard can then present historic and predicted incident distributions. It also allows responders to analyze how moving or adding depots (stations for emergency responders) affects average response times, and can make dispatching recommendations based on heuristics. Broadly, it is a one-stop tool that helps responders visualize historical data as well as plan for and respond to incidents.","Title: A CPS toolchain for learning-based systems - demo abstract.\nYear: 2019\n\nAbstract: Cyber-Physical Systems (CPS) are expected to perform tasks with ever-increasing levels of autonomy, often in highly uncertain environments. Traditional design techniques based on domain knowledge and analytical models are often unable to cope with epistemic uncertainties present in these systems. This challenge, combined with recent advances in machine learning, has led to the emergence of Learning-Enabled Components (LECs) in CPS. However, very little tool support is available for design automation of these systems. In this demonstration, we introduce an integrated toolchain for the development of CPS with LECs with support for architectural modeling, data collection, system software deployment, and LEC training, evaluation, and verification. Additionally, the toolchain supports the modeling and analysis of safety cases - a critical part of the engineering process for mission and safety critical systems.","Title: Model-based design for CPS with learning-enabled components.\nYear: 2019\n\nAbstract: Recent advances in machine learning led to the appearance of Learning-Enabled Components (LECs) in Cyber-Physical Systems. LECs are being evaluated and used for various, complex functions including perception and control. However, very little tool support is available for design automation in such systems. This paper introduces an integrated toolchain that supports the architectural modeling of CPS with LECs, but also has extensive support for the engineering and integration of LECs, including support for training data collection, LEC training, LEC evaluation and verification, and system software deployment. Additionally, the toolsuite supports the modeling and analysis of safety cases - a critical part of the engineering process for mission and safety critical systems.","Title: Towards demand-oriented flexible rerouting of public transit under uncertainty.\nYear: 2019\n\nAbstract: This paper proposes a flexible rerouting strategy for the public transit to accommodate the spatio-temporal variation in the travel demand. Transit routes are typically static in nature, i.e., the buses serve well-defined routes; this results in people living in away from the bus routes choose alternate transit modes such as private automotive vehicles resulting in ever-increasing traffic congestion. In the flex-transit mode, we reroute the buses to accommodate high travel demand areas away from the static routes considering its spatio-temporal variation. We perform clustering to identify several flex stops; these are stops not on the static routes, but with high travel demand around them. We divide the bus stops on the static routes into critical and non-critical bus stops; critical bus stops refer to transfer points, where people change bus routes to reach their destinations. In the existing static scheduling process, some slack time is provided at the end of each trip to account for any travel delays. Thus, the additional travel time incurred due to taking flexible routes is constrained to be less than the available slack time. We use the percent increase in travel demand to analyze the effectiveness of the rerouting process. The proposed methodology is demonstrated using real-world travel data for Route 7 operated by the Nashville Metropolitan Transit Authority (MTA).","Title: Cyber-physical simulation platform for security assessment of transactive energy systems\nYear: 2019\n\nAbstract: Transactive energy systems (TES) are emerging as a transformative solution for the problems that distribution system operators face due to an increase in the use of distributed energy resources and rapid growth in scalability of managing active distribution system (ADS). On the one hand, these changes pose a decentralized power system control problem, requiring strategic control to maintain reliability and resiliency for the community and for the utility. On the other hand, they require robust financial markets while allowing participation from diverse prosumers. To support the computing and flexibility requirements of TES while preserving privacy and security, distributed software platforms are required. In this paper, we enable the study and analysis of security concerns by developing Transactive Energy Security Simulation Testbed (TESST), a TES testbed for simulating various cyber attacks. In this work, the testbed is used for TES simulation with centralized clearing market, highlighting weaknesses in a centralized system. Additionally, we present a blockchain enabled decentralized market solution supported by distributed computing for TES, which on one hand can alleviate some of the problems that we identify, but on the other hand, may introduce newer issues. Future study of these differing paradigms is necessary and will continue as we develop our security simulation testbed.","Title: Augmenting Learning Components for Safety in Resource Constrained Autonomous Robots\nYear: 2019\n\nAbstract: Learning enabled components (LECs) trained using data-driven algorithms are increasingly being used in autonomous robots commonly found in factories, hospitals, and educational laboratories. However, these LECs do not provide any safety guarantees, and testing them is challenging. In this paper, we introduce a framework that performs weighted simplex strategy based supervised safety control, resource management and confidence estimation of autonomous robots. Specifically, we describe two weighted simplex strategies: (a) simple weighted simplex strategy (SW-Simplex) that computes a weighted controller output by comparing the decisions between a safety supervisor and an LEC, and (b) a context-sensitive weighted simplex strategy (CSW-Simplex) that computes a context-aware weighted controller output. We use reinforcement learning to learn the contextual weights. We also introduce a system monitor that uses the current state information and a Bayesian network model learned from past data to estimate the probability of the robotic system staying in the safe working region. To aid resource constrained robots in performing complex computations of these weighted simplex strategies, we describe a resource manager that offloads tasks to an available fog nodes. The paper also describes a hardware testbed called DeepNNCar, which is a low cost resource-constrained RC car, built to perform autonomous driving. Using the hardware, we show that both SW-Simplex and CSW-Simplex have 40% and 60% fewer safety violations, while demonstrating higher optimized speed during indoor driving (~ 0.40 m/s) than the original system (using only LECs).","Title: Towards an Adaptive Multi-Modal Traffic Analytics Framework at the Edge\nYear: 2019\n\nAbstract: The Internet of Things (IoT) requires distributed, large scale data collection via geographically distributed devices. While IoT devices typically send data to the cloud for processing, this is problematic for bandwidth constrained applications. Fog and edge computing (processing data near where it is gathered, and sending only results to the cloud) has become more popular, as it lowers network overhead and latency. Edge computing often uses devices with low computational capacity, therefore service frameworks and middleware are needed to efficiently compose services. While many frameworks use a top-down perspective, quality of service is an emergent property of the entire system and often requires a bottom up approach. We define services as multi-modal, allowing resource and performance tradeoffs. Different modes can be composed to meet an application's high level goal, which is modeled as a function. We examine a case study for counting vehicle traffic through intersections in Nashville. We apply object detection and tracking to video of the intersection, which must be performed at the edge due to privacy and bandwidth constraints. We explore the hardware and software architectures, and identify the various modes. This paper lays the foundation to formulate the online optimization problem presented by the system which makes tradeoffs between the quantity of services and their quality constrained by available resources.","Title: Demo: Transactive Energy Application with RIAPS\nYear: 2019\n\nAbstract: The modern electric grid is a complex, decentralized cyber-physical system requiring higher-level control techniques to balance the demand and supply of energy to optimize the overall energy usage. The concept of Transactive Energy utilizes distributed system principle to address this challenge. In this demonstration we show the usage of the distributed application management platform RIAPS in the implementation of one such Transactive Energy approach to control elements of a power system, which runs as a a simulation using the Gridlab-d simulation solver.","Title: DeepNNCar: A Testbed for Deploying and Testing Middleware Frameworks for Autonomous Robots\nYear: 2019\n\nAbstract: This demo showcases the features of an adaptive middleware framework for resource constrained autonomous robots like DeepNNCar (Figure 1). These robots use Learning Enabled Components (LECs), trained with deep learning models to perform control actions. However, these LECs do not provide any safety guarantees and testing them is challenging. To overcome these challenges, we have developed an adaptive middleware framework that (1) augments the LEC with safety controllers that can use different weighted simplex strategies to improve the systems safety guarantees, and (2) includes a resource manager to monitor the resource parameters (temperature, CPU Utilization), and offload tasks at runtime. Using DeepNNCar we will demonstrate the framework and its capability to adaptively switch between the controllers and strategies based on its safety and speed performance.","Title: Short Paper: Towards An Edge-Located Time-Series Database\nYear: 2019\n\nAbstract: Smart infrastructure demands resilient data storage, and emerging applications execute queries on this data over time. Typically, time-series databases serve these queries; however, cloud-based time-series storage can be prohibitively expensive. As smart devices proliferate, the amount of computing power and memory available in our connected infrastructure provides the opportunity to move resilient time-series data storage and analytics to the edge. This paper proposes time-series storage in a Distributed Hash Table (DHT), and a novel key-generation technique that provides time-indexed reads and writes for key-value pairs. Experimental results show this technique meets demands for smart infrastructure situations.","Title: On the Design of Fault- Tolerance in a Decentralized Software Platform for Power Systems\nYear: 2019\n\nAbstract: The vision of the `Smart Grid' assumes a distributed real-time embedded system that implements various monitoring and control functions. As the reliability of the power grid is critical to modern society, the software supporting the grid must support fault tolerance and resilience in the resulting cyber-physical system. This paper describes the fault-tolerance features of a software framework called Resilient Information Architecture Platform for Smart Grid (RIAPS). The framework supports various mechanisms for fault detection and mitigation and works in concert with the applications that implement the grid-specific functions. The paper discusses the design philosophy for and the implementation of the fault tolerance features and presents an application example to show how it can be used to build highly resilient systems.","Title: Analyzing The Cascading Effect Of Traffic Congestion Using Lstm Networks\nYear: 2019\n\nAbstract: This paper presents a data-driven approach for predicting the propagation of traffic congestion at road segments as a function of the congestion in their neighboring segments. In the past, this problem has mostly been addressed by modelling the traffic congestion over some standard physical phenomenon through which it is difficult to capture all the modalities of such a dynamic and complex system. While other recent works have focused on applying a generalized data-driven technique on the whole network at once, they often ignore intersection characteristics. On the contrary, we propose a citywide ensemble of intersection level connected LSTM models and propose mechanisms for identifying congestion events using the predictions from the networks. To reduce the search space of likely congestion sinks we use the likelihood of congestion propagation in neighboring road segments of a congestion source that we learn from the past historical data. We validated our congestion forecasting framework on the real world traffic data of Nashville, USA and identified the onset of congestion in each of the neighboring segments of any congestion source with an average precision of 0.9269 and an average recall of 0.9118 tested over ten congestion events.","Title: Cyber-Attacks and Mitigation in Blockchain Based Transactive Energy Systems\nYear: 2020\n\nAbstract: Power grids are undergoing major changes due to the rapid adoption of intermittent renewable energy resources and the increased availability of energy storage devices. These trends drive smart-grid operators to envision a future where peer-to-peer energy trading occurs within microgrids, leading to the development of Transactive Energy Systems. Blockchains have garnered significant interest from both academia and industry for their potential application in decentralized TES, in large part due to their high level of resilience. In this paper, we introduce a novel class of attacks against blockchain based TES, which target the gateways that connect market participants to the system. We introduce a general model of blockchain based TES and study multiple threat models and attack strategies. We also demonstrate the impact of these attacks using a testbed based on GridLAB-D and a private Ethereum network. Finally, we study how to mitigate these attack.","Title: TRANSIT-GYM: A Simulation and Evaluation Engine for Analysis of Bus Transit Systems\nYear: 2021\n\nAbstract: Public-transit systems face a number of operational challenges: (a) changing ridership patterns requiring optimization of fixed line services, (b) optimizing vehicle-to-trip assignments to reduce maintenance and operation codes, and (c) ensuring equitable and fair coverage to areas with low ridership. Optimizing these objectives presents a hard computational problem due to the size and complexity ...","Title: Energy and Emission Prediction for Mixed-Vehicle Transit Fleets Using Multi-task and Inductive Transfer Learning\nYear: 2021\n\nAbstract: Public transit agencies are focused on making their fixed-line bus systems more energy efficient by introducing electric (EV) and hybrid (HV) vehicles to their fleets. However, because of the high upfront cost of these vehicles, most agencies are tasked with managing a mixed-fleet of internal combustion vehicles (ICEVs), EVs, and HVs. In managing mixed-fleets, agencies require accurate predictions of energy use for optimizing the assignment of vehicles to transit routes, scheduling charging, and ensuring that emission standards are met. The current state-of-the-art is to develop separate neural network models to predict energy consumption for each vehicle class. Although different vehicle classes' energy consumption depends on a varied set of covariates, we hypothesize that there are broader generalizable patterns that govern energy consumption and emissions. In this paper, we seek to extract these patterns to aid learning to address two problems faced by transit agencies. First, in the case of a transit agency which operates many ICEVs, HVs, and EVs, we use multi-task learning (MTL) to improve accuracy of forecasting energy consumption. Second, in the case where there is a significant variation in vehicles in each category, we use inductive transfer learning (ITL) to improve predictive accuracy for vehicle class models with insufficient data. As this work is to be deployed by our partner agency, we also provide an online pipeline for joining the various sensor streams for fixed-line transit energy prediction. We find that our approach outperforms vehicle-specific baselines in both the MTL and ITL settings.","Title: User-centric Distributed Route Planning in Smart Cities based on Multi-objective Optimization\nYear: 2021\n\nAbstract: The realization of edge-based cyber-physical systems (CPS) poses important challenges in terms of performance, robustness, security, etc. This paper examines a novel approach to providing a user-centric adaptive route planning service over a network of Road Side Units (RSUs) in smart cities. The key idea is to adaptively select routing task parameters such as privacy-cloaked area sizes and number ...","Title: Learning Incident Prediction Models Over Large Geographical Areas for Emergency Response\nYear: 2021\n\nAbstract: Emergency Response Management (ERM) necessitates the use of models capable of predicting the spatial-temporal likelihood of incident occurrence. These models are used for proactive stationing in order to reduce overall response time. Traditional methods simply aggregate past incidents over space and time; such approaches fail to make useful short-term predictions when the spatial region is large a...","Title: Power-attack: a comprehensive tool-chain for modeling and simulating attacks in power systems\nYear: 2021\n\nAbstract: ABSTRACTDue to the increased deployment of novel communication, control and protection functions, the grid has become vulnerable to a variety of attacks. Designing robust machine learning based attack detection and mitigation algorithms require large amounts of data that rely heavily on a representative environment, where different attacks can be simulated. This paper presents a comprehensive tool-chain for modeling and simulating attacks in power systems. The paper makes the following contributions, first, we present a probabilistic domain specific language to define multiple attack scenarios and simulation configuration parameters. Secondly, we extend the PyPower-dynamics simulator with protection system components to simulate cyber attacks in control and protection layers of power system. In the end, we demonstrate multiple attack scenarios with a case study based on IEEE 39 bus system.","Title: RT-METER: a real-time, multi-layer cyber-power testbed for resiliency analysis\nYear: 2021\n\nAbstract: ABSTRACTIn this work, we present a Real-Time, Multi-layer cybEr-power TestbEd for the Resiliency analysis (RT-METER) to support power grid operation and planning. Developed cyber-power testbed provides a mechanism for end-to-end validation of advanced tools for cyber-power grid monitoring, control, and planning. By integrating a host of features across three core layers-physical power system, communication network, and monitoring/control center with advanced tools,---the testbed provides a platform to model and simulate rich and diverse cyber-power grid scenarios and generating realistic sensors, system, and network data. These data are subsequently used in validating advanced tools to assist operators during complex and challenging scenarios, which is essential for the successful operation of the future grid. We detail a suite of algorithmic tools validated using the developed testbed and the generated realistic grid data.","Title: Data-Driven Prediction and Optimization of Energy Use for Transit Fleets of Electric and ICE Vehicles\nYear: 2022\n\nAbstract: AbstractDue to the high upfront cost of electric vehicles, many public transit agencies can afford only mixed fleets of internal combustion and electric vehicles. Optimizing the operation of such mixed fleets is challenging because it requires accurate trip-level predictions of electricity and fuel use as well as efficient algorithms for assigning vehicles to transit routes. We present a novel framework for the data-driven prediction of trip-level energy use for mixed-vehicle transit fleets and for the optimization of vehicle assignments, which we evaluate using data collected from the bus fleet of CARTA, the public transit agency of Chattanooga, TN. We first introduce a data collection, storage, and processing framework for system-level and high-frequency vehicle-level transit data, including domain-specific data cleansing methods. We train and evaluate machine learning models for energy prediction, demonstrating that deep neural networks attain the highest accuracy. Based on these predictions, we formulate the problem of minimizing energy use through assigning vehicles to fixed-route transit trips. We propose an optimal integer program as well as efficient heuristic and meta-heuristic algorithms, demonstrating the scalability and performance of these algorithms numerically using the transit network of CARTA.","Title: Practitioner-Centric Approach for Early Incident Detection Using Crowdsourced Data for Emergency Services\nYear: 2021\n\nAbstract: Emergency response is highly dependent on the time of incident reporting. Unfortunately, the traditional approach to receiving incident reports (e.g., calling 911 in the USA) has time delays. Crowdsourcing platforms such as Waze provide an opportunity for early identification of incidents. However, detecting incidents from crowdsourced data streams is difficult due to the challenges of noise and uncertainty associated with such data. Further, simply optimizing over detection accuracy can compromise spatial-temporal localization of the inference, thereby making such approaches infeasible for real-world deployment. This paper presents a novel problem formulation and solution approach for practitioner-centered incident detection using crowdsourced data by using emergency response management as a case-study. The proposed approach CROME (Crowdsourced Multi-objective Event Detection) quantifies the relationship between the performance metrics of incident classification (e.g., F1 score) and the requirements of model practitioners (e.g., 1 km. radius for incident detection). First, we show how crowdsourced reports, ground-truth historical data, and other relevant determinants such as traffic and weather can be used together in a Convolutional Neural Network (CNN) architecture for early detection of emergency incidents. Then, we use a Pareto optimization-based approach to optimize the output of the CNN in tandem with practitioner-centric parameters to balance detection accuracy and spatial-temporal localization. Finally, we demonstrate the applicability of this approach using crowdsourced data from Waze and traffic accident reports from Nashville, TN, USA. Our experiments demonstrate that the proposed approach outperforms existing approaches in incident detection while simultaneously optimizing the needs for real-world deployment and usability.","Title: Automated Method for Assurance Case Construction from System Design Models\nYear: 2021\n\nAbstract: Many Cyber Physical Systems (CPSs) operate in safety- or mission-critical applications where strong assurance of safe operation is required. Assurance cases are one widely used tool for presenting an argument in support of system safety requirements backed by a body of evidence - e.g., test data, formal analysis, or expert review. A system assurance case should regularly evolve during the developm...","Title: Risk-Aware Scene Sampling for Dynamic Assurance of Autonomous Systems\nYear: 2022\n\nAbstract: Autonomous Cyber-Physical Systems must often operate under uncertainties like sensor degradation and shifts in the operating conditions, which increases its operational risk. Dynamic Assurance of these systems requires designing runtime safety components like Out-of-Distribution detectors and risk estimators, which require labeled data from different operating modes of the system that belong to sc...","Title: An Online Approach to Solve the Dynamic Vehicle Routing Problem with Stochastic Trip Requests for Paratransit Services\nYear: 2022\n\nAbstract: Many transit agencies operating paratransit and microtransit ser-vices have to respond to trip requests that arrive in real-time, which entails solving hard combinatorial and sequential decision-making problems under uncertainty. To avoid decisions that lead to signifi-cant inefficiency in the long term, vehicles should be allocated to requests by optimizing a non-myopic utility function or by batching requests together and optimizing a myopic utility function. While the former approach is typically offline, the latter can be performed online. We point out two major issues with such approaches when applied to paratransit services in practice. First, it is difficult to batch paratransit requests together as they are temporally sparse. Second, the environment in which transit agencies operate changes dynamically (e.g., traffic conditions can change over time), causing the estimates that are learned offline to become stale. To address these challenges, we propose a fully online approach to solve the dynamic vehicle routing problem (DVRP) with time windows and stochastic trip requests that is robust to changing environmental dynamics by construction. We focus on scenarios where requests are relatively sparse-our problem is motivated by applications to paratransit services. We formulate DVRP as a Markov decision process and use Monte Carlo tree search to evaluate actions for any given state. Accounting for stochastic requests while optimizing a non-myopic utility function is computationally challenging; indeed, the action space for such a problem is intractably large in practice. To tackle the large action space, we leverage the structure of the problem to design heuristics that can sample promising actions for the tree search. Our experiments using real-world data from our partner agency show that the proposed approach outperforms existing state-of-the-art approaches both in terms of performance and robustness.","Title: Offline Vehicle Routing Problem with Online Bookings: A Novel Problem Formulation with Applications to Paratransit.\nYear: 2022\n\nAbstract: Vehicle routing problems (VRPs) can be divided into two major categories: offline VRPs, which consider a given set of trip requests to be served, and online VRPs, which consider requests as they arrive in real-time. Based on discussions with public transit agencies, we identify a real-world problem that is not addressed by existing formulations: booking trips with flexible pickup windows (e.g., 3 hours) in advance (e.g., the day before) and confirming tight pickup windows (e.g., 30 minutes) at the time of booking. Such a service model is often required in paratransit service settings, where passengers typically book trips for the next day over the phone. To address this gap between offline and online problems, we introduce a novel formulation, the offline vehicle routing problem with online bookings. This problem is very challenging computationally since it faces the complexity of considering large sets of requests -- similar to offline VRPs -- but must abide by strict constraints on running time -- similar to online VRPs. To solve this problem, we propose a novel computational approach, which combines an anytime algorithm with a learning-based policy for real-time decisions. Based on a paratransit dataset obtained from our partner transit agency, we demonstrate that our novel formulation and computational approach lead to significantly better outcomes in this service setting than existing algorithms.","Title: ADVISER: AI-Driven Vaccination Intervention Optimiser for Increasing Vaccine Uptake in Nigeria.\nYear: 2022\n\nAbstract: More than 5 million children under five years die from largely preventable or treatable medical conditions every year, with an overwhelmingly large proportion of deaths occurring in under-developed countries with low vaccination uptake. One of the United Nations' sustainable development goals (SDG 3) aims to end preventable deaths of newborns and children under five years of age. We focus on Nigeria, where the rate of infant mortality is appalling. We collaborate with HelpMum, a large non-profit organization in Nigeria to design and optimize the allocation of heterogeneous health interventions under uncertainty to increase vaccination uptake, the first such collaboration in Nigeria. Our framework, ADVISER: AI-Driven Vaccination Intervention Optimiser, is based on an integer linear program that seeks to maximize the cumulative probability of successful vaccination. Our optimization formulation is intractable in practice. We present a heuristic approach that enables us to solve the problem for real-world use-cases. We also present theoretical bounds for the heuristic method. Finally, we show that the proposed approach outperforms baseline methods in terms of vaccination uptake through experimental evaluation. HelpMum is currently planning a pilot program based on our approach to be deployed in the largest city of Nigeria, which would be the first deployment of an AI-driven vaccination uptake program in the country and hopefully, pave the way for other data-driven programs to improve health outcomes in Nigeria.","Title: Moving target defense for the security and resilience of mixed time and event triggered cyber–physical systems\nYear: 2022\n\nAbstract: Memory corruption attacks such as code injection, code reuse, and non-control data attacks have become widely popular for compromising safety-critical Cyber–Physical Systems (CPS). Moving target defense (MTD) techniques such as instruction set randomization (ISR), address space randomization (ASR), and data space randomization (DSR) can be used to protect systems against such attacks. CPS often use time-triggered architectures to guarantee predictable and reliable operation. MTD techniques can cause time delays with unpredictable behavior. To protect CPS against memory corruption attacks, MTD techniques can be implemented in a mixed time and event-triggered architecture that provides capabilities for maintaining safety and availability during an attack. This paper presents a mixed time and event-triggered MTD security approach based on the ARINC 653 architecture that provides predictable and reliable operation during normal operation and rapid detection and reconfiguration upon detection of attacks. We leverage a hardware-in-the-loop testbed and an advanced emergency braking system (AEBS) case study to show the effectiveness of our approach.","Title: Syntheto: A Surface Language for APT and ACL2.\nYear: 2022\n\nAbstract: Syntheto is a surface language for carrying out formally verified program synthesis by transformational refinement in ACL2 using the APT toolkit. Syntheto aims at providing more familiarity and automation, in order to make this technology more widely usable. Syntheto is a strongly statically typed functional language that includes both executable and non-executable constructs, including facilities to state and prove theorems and facilities to apply proof-generating transformations. Syntheto is integrated into an IDE with a notebook-style, interactive interface that translates Syntheto to ACL2 definitions and APT transformation invocations, and back-translates the prover's results to Syntheto; the bidirectional translation happens behind the scenes, with the user interacting solely with Syntheto.","Title: ANTI-CARLA: An Adversarial Testing Framework for Autonomous Vehicles in CARLA.\nYear: 2022\n\nAbstract: Despite recent advances in autonomous driving systems, accidents such as the fatal Uber crash in 2018 show these systems are still susceptible to edge cases. Such systems must be thoroughly tested and validated before being deployed in the real world to avoid such events. Testing in open-world scenarios can be difficult, time-consuming, and expensive. These challenges can be addressed by using driving simulators such as CARLA instead. A key part of such tests is adversarial testing, in which the goal is to find scenarios that lead to failures of the given system. While several independent efforts in testing have been made, a well-established testing framework that enables adversarial testing has yet to be made available for CARLA. We therefore propose ANTI-CARLA, an automated testing framework in CARLA for simulating adversarial weather conditions (e.g., heavy rain) and sensor faults (e.g., camera occlusion) that fail the system. The operating conditions in which a given system should be tested are specified in a scenario description language. The framework offers an efficient search mechanism that searches for adversarial operating conditions that will fail the tested system. In this way, ANTI-CARLA extends the CARLA simulator with the capability of performing adversarial testing on any given driving pipeline. We use ANTI-CARLA to test the driving pipeline trained with Learning By Cheating (LBC) approach. The simulation results demonstrate that ANTI-CARLA can effectively and automatically find a range of failure cases despite LBC reaching an accuracy of 100% in the CARLA benchmark.","Title: Anomaly based Incident Detection in Large Scale Smart Transportation Systems\nYear: 2022\n\nAbstract: Modern smart cities are focusing on smart transportation solutions to detect and mitigate the effects of various traffic incidents in the city. To materialize this, roadside units and ambient trans-portation sensors are being deployed to collect vehicular data that provides real-time traffic monitoring. In this paper, we first propose a real-time data-driven anomaly-based traffic incident detection framework for a city-scale smart transportation system. Specifically, we propose an incremental region growing approximation algorithm for optimal Spatio-temporal clustering of road segments and their data; such that road segments are strategically divided into highly correlated clusters. The highly correlated clusters enable identifying a Pythagorean Mean-based invariant as an anomaly detection metric that is highly stable under no incidents but shows a deviation in the presence of incidents. We learn the bounds of the invariants in a robust manner such that anomaly detection can generalize to unseen events, even when learning from real noisy data. We perform extensive experimental validation using mobility data collected from the City of Nashville, Tennessee, and prove that the method can detect incidents within each cluster in real-time.","Title: Neural Architecture and Feature Search for Predicting the Ridership of Public Transportation Routes\nYear: 2022\n\nAbstract: Accurately predicting the ridership of public-transit routes provides substantial benefits to both transit agencies, who can dispatch additional vehicles proactively before the vehicles that serve a route become crowded, and to passengers, who can avoid crowded vehicles based on publicly available predictions. The spread of the coronavirus disease has further elevated the importance of ridership prediction as crowded vehicles now present not only an inconvenience but also a public-health risk. At the same time, accurately predicting ridership has become more challenging due to evolving ridership patterns, which may make all data except for the most recent records stale. One promising approach for improving prediction accuracy is to fine-tune the hyper-parameters of machine-learning models for each transit route based on the characteristics of the particular route, such as the number of records. However, manually designing a machine-learning model for each route is a labor-intensive process, which may require experts to spend a significant amount of their valuable time. To help experts with designing machine-learning models, we propose a neural-architecture and feature search approach, which optimizes the architecture and features of a deep neural network for predicting the ridership of a public-transit route. Our approach is based on a randomized local hyper-parameter search, which minimizes both prediction error as well as the complexity of the model. We evaluate our approach on real-world ridership data provided by the public transit agency of Chattanooga, TN, and we demonstrate that training neural networks whose architectures and features are optimized for each route provides significantly better performance than training neural networks whose architectures and features are generic.","Title: Automating Pattern Selection for Assurance Case Development for Cyber-Physical Systems\nYear: 2022\n\nAbstract: Assurance Cases are increasingly being required for regulatory acceptance of Cyber-Physical Systems. However, the ever-increasing complexity of these systems has made the assurance cases development complex, labor-intensive and time-consuming. Assurance case fragments called patterns are used to handle the complexity. The state-of-the-art approach has been to manually select generic patterns from online catalogs, instantiate them with system-specific information, and assemble them into an assurance case. While there has been some work in automating the instantiation and assembly, a less researched area is the automation of the pattern selection process, which takes a considerable amount of the assurance case development time. To close this automation gap, we have developed an automated pattern selection workflow that handles the selection problem as a coverage problem, intending to find the smallest set of patterns that can cover the available system artifacts. For this, we utilize the ontology graphs of the system artifacts and the patterns and perform graph analytics. The selected patterns are fed into an external instantiation function to develop an assurance case. Then, they are evaluated for coverage using two coverage metrics. An illustrative autonomous vehicle example is provided, demonstrating the utility of the proposed workflow in developing an assurance case with reduced efforts and time compared to the manual development alternative."],"string":"[\n \"Title: Integrated Monitoring and Control for Performance Management of Distributed Enterprise Systems\\nYear: 2010\\n\\nAbstract: This paper describes an integrated monitoring and control framework for managing performance of distributed enterprise systems.\",\n \"Title: Application of software health management techniques\\nYear: 2011\\n\\nAbstract: The growing complexity of software used in large-scale, safety critical cyber-physical systems makes it increasingly difficult to expose and hence correct all potential defects. There is a need to augment the existing fault tolerance methodologies with new approaches that address latent software defects exposed at runtime. This paper describes an approach that borrows and adapts traditional 'System Health Management' techniques to improve software dependability through simple formal specification of runtime monitoring, diagnosis, and mitigation strategies. The two-level approach to health management at the component and system level is demonstrated on a simulated case study of an Air Data Inertial Reference Unit (ADIRU). An ADIRU was categorized as the primary failure source for the in-flight upset caused in the Malaysian Air flight 124 over Perth, Australia in 2005.\",\n \"Title: A capacity planning process for performance assurance of component-based distributed systems (abstracts only)\\nYear: 2011\\n\\nAbstract: For service providers of multi-tiered component-based applications, such as web portals, assuring high performance and availability to their customers without impacting revenue requires effective and careful capacity planning that aims at minimizing the number of resources, and utilizing them efficiently while simultaneously supporting a large customer base and meeting their service level agreements. This paper presents a novel, hybrid capacity planning process that results from a systematic blending of 1) analytical modeling, where traditional modeling techniques are enhanced to overcome their limitations in providing accurate performance estimates; 2) profile-based techniques, which determine performance profiles of individual software components for use in resource allocation and balancing resource usage; and 3) allocation heuristics that determine minimum number of resources to allocate software components. Our results illustrate that using our technique, performance (i.e., bounded response time) can be assured while reducing operating costs by using 25% less resources and increasing revenues by handling 20% more clients compared to traditional approaches.\",\n \"Title: Efficient Autoscaling in the Cloud Using Predictive Models for Workload Forecasting\\nYear: 2011\\n\\nAbstract: Large-scale component-based enterprise applications that leverage Cloud resources expect Quality of Service(QoS) guarantees in accordance with service level agreements between the customer and service providers. In the context of Cloud computing, auto scaling mechanisms hold the promise of assuring QoS properties to the applications while simultaneously making efficient use of resources and keeping operational costs low for the service providers. Despite the perceived advantages of auto scaling, realizing the full potential of auto scaling is hard due to multiple challenges stemming from the need to precisely estimate resource usage in the face of significant variability in client workload patterns. This paper makes three contributions to overcome the general lack of effective techniques for workload forecasting and optimal resource allocation. First, it discusses the challenges involved in auto scaling in the cloud. Second, it develops a model-predictive algorithm for workload forecasting that is used for resource auto scaling. Finally, empirical results are provided that demonstrate that resources can be allocated and deal located by our algorithm in a way that satisfies both the application QoS while keeping operational costs low.\",\n \"Title: Towards a resilient deployment and configuration infrastructure for fractionated spacecraft\\nYear: 2013\\n\\nAbstract: Fractionated spacecraft are clusters of small, independent modules that interact wirelessly to realize the functionality of a traditional monolithic spacecraft. System F6 (F6 stands for Future, Fast, Flexible, Fractionated, Free-Flying spacecraft) is a DARPA program for fractionated spacecraft. Software applications in F6 are implemented in the context of the F6 Information Architecture Platform (IAP), which provides component-based abstractions for composing distributed applications. The lifecycle of these distributed applications must be managed autonomously by a deployment and configuration (D&C) infrastructure, which can redeploy and reconfigure the running applications in response to faults and other anomalies that may occur during system operation. Addressing these D&C requirements is hard due to the significant fluctuation in resource availabilities, constraints on resources, and safety and security concerns. This paper presents the key architectural ideas that are required in realizing such a D&C infrastructure.\",\n \"Title: A component model for hard real-time systems: CCM with ARINC-653\\nYear: 2011\\n\\nAbstract: The size and complexity of software in safety-critical systems is increasing at a rapid pace. One technology that can be used to mitigate this complexity is component-based software development. However, in spite of the apparent benefits of a component-based approach to development, little work has been done in applying these concepts to hard real-time systems. This paper improves the state of the art by making three contributions: (1) we present a component model for hard real-time systems and define the semantics of different types of component interactions; (2) we present an implementation of a middleware that supports this component model. This middleware combines an open-source CORBA Component Model (CCM) implementation (MICO) with ARINC-653: a state-of-the-art real-time operating systems (RTOS) standard, (3) finally; we describe a modeling environment that enables design, analysis, and deployment of component assemblies. We conclude with a discussion of the lessons learned during this exercise. Our experiences point toward extending both the CCM as well as revising the ARINC-653. Copyright © 2011 John Wiley & Sons, Ltd.\",\n \"Title: Deliberative, search-based mitigation strategies for model-based software health management\\nYear: 2013\\n\\nAbstract: Rising software complexity in aerospace systems makes them very difficult to analyze and prepare for all possible fault scenarios at design time; therefore, classical run-time fault tolerance techniques such as self-checking pairs and triple modular redundancy are used. However, several recent incidents have made it clear that existing software fault tolerance techniques alone are not sufficient. To improve system dependability, simpler, yet formally specified and verified run-time monitoring, diagnosis, and fault mitigation capabilities are needed. Such architectures are already in use for managing the health of vehicles and systems. Software health management is the application of these techniques to software systems. In this paper, we briefly describe the software health management techniques and architecture developed by our research group. The foundation of the architecture is a real-time component framework (built upon ARINC-653 platform services) that defines a model of computation for software components. Dedicated architectural elements: the Component Level Health Manager (CLHM) and System Level Health Manager (SLHM) provide the health management services: anomaly detection, fault source isolation, and fault mitigation. The SLHM includes a diagnosis engine that (1) uses a Timed Failure Propagation Graph (TFPG) model derived from the component assembly model, (2) reasons about cascading fault effects in the system, and (3) isolates the fault source component(s). Thereafter, the appropriate system-level mitigation action is taken. The main focus of this article is the description of the fault mitigation architecture that uses goal-based deliberative reasoning to determine the best mitigation actions for recovering the system from the identified failure mode.\",\n \"Title: Modeling and Analysis of Probabilistic Timed Systems\\nYear: 2009\\n\\nAbstract: Probabilistic models are useful for analyzing systems which operate under the presence of uncertainty. In this paper, we present a technique for verifying safety and liveness properties for probabilistic timed automata. The proposed technique is an extension of a technique used to verify stochastic hybrid automata using an approximation with Markov Decision Processes. A case study for CSMA/CD protocol has been used to show case the methodology used in our technique.\",\n \"Title: Compensating for Timing Jitter in Computing Systems with General-Purpose Operating Systems\\nYear: 2009\\n\\nAbstract: Fault-tolerant frameworks for large scale computing clusters require sensor programs, which are executed periodically to facilitate performance and fault management. By construction, these clusters use general purpose operating systems such as Linux that are built for best average case performance and do not provide deterministic scheduling guarantees. Consequently, periodic applications show jitter in execution times relative to the expected execution time. Obtaining a deterministic schedule for periodic tasks in general purpose operating systems is difficult without using kernel-level modifications such as RTAI and RTLinux. However, due to performance and administrative issues kernel modification cannot be used in all scenarios. In this paper, we address the problem of jitter compensation for periodic tasks that cannot rely on modifying the operating system kernel. ; Towards that, (a) we present motivating examples; (b) we present a feedback controller based approach that runs in the user space and actively compensates periodic schedule based on past jitter; This approach is platform-agnostic i.e. it can be used in different operating systems without modification; and (c) we show through analysis and experiments that this approach is platform-agnostic i.e. it can be used in different operating systems without modification and also that it maintains a stable system with bounded total jitter.\",\n \"Title: Towards a verifiable real-time, autonomic, fault mitigation framework for large scale real-time systems\\nYear: 2007\\n\\nAbstract: Designing autonomic fault responses is difficult, particularly in large-scale systems, as there is no single ‘perfect’ fault\\n mitigation response to a given failure. The design of appropriate mitigation actions depend upon the goals and state of the\\n application and environment. Strict time deadlines in real-time systems further exacerbate this problem. Any autonomic behavior\\n in such systems must not only be functionally correct but should also conform to properties of liveness, safety and bounded\\n time responsiveness. This paper details a real-time fault-tolerant framework, which uses a reflex and healing architecture\\n to provide fault mitigation capabilities for large-scale real-time systems. At the heart of this architecture is a real-time\\n reflex engine, which has a state-based failure management logic that can respond to both event- and time-based triggers. We\\n also present a semantic domain for verifying properties of systems, which use this framework of real-time reflex engines.\\n Lastly, a case study, which examines the details of such an approach, is presented.\",\n \"Title: A capacity planning process for performance assurance of component-based distributed systems\\nYear: 2011\\n\\nAbstract: For service providers of multi-tiered component-based applications, such as web portals, assuring high performance and availability to their customers without impacting revenue requires effective and careful capacity planning that aims at minimizing the number of resources, and utilizing them efficiently while simultaneously supporting a large customer base and meeting their service level agreements. This paper presents a novel, hybrid capacity planning process that results from a systematic blending of 1) analytical modeling, where traditional modeling techniques are enhanced to overcome their limitations in providing accurate performance estimates; 2) profile-based techniques, which determine performance profiles of individual software components for use in resource allocation and balancing resource usage; and 3) allocation heuristics that determine minimum number of resources to allocate software components. Our results illustrate that using our technique, performance (i.e., bounded response time) can be assured while reducing operating costs by using 25% less resources and increasing revenues by handling 20% more clients compared to traditional approaches.\",\n \"Title: Scientific Computing Autonomic Reliability Framework\\nYear: 2008\\n\\nAbstract: Large scientific computing clusters require a distributed dependability subsystem that can provide fault isolation and recovery and is capable of learning and predicting failures, to improve the reliability of scientific workflows. In this paper, we outline the key ideas in the design of a Scientific Computing Autonomic Reliability Framework (SCARF) for large computing clusters used in the Lattice Quantum Chromo Dynamics project at Fermi Lab.\",\n \"Title: Comprehensive Border Bases for Zero Dimensional Parametric Polynomial Ideals.\\nYear: 2013\\n\\nAbstract: In this paper, we extend the idea of comprehensive Gr\\\\\\\"{o}bner bases given by Weispfenning (1992) to border bases for zero dimensional parametric polynomial ideals. For this, we introduce a notion of comprehensive border bases and border system, and prove their existence even in the cases where they do not correspond to any term order. We further present algorithms to compute comprehensive border bases and border system. Finally, we study the relation between comprehensive Gr\\\\\\\"{o}bner bases and comprehensive border bases w.r.t. a term order and give an algorithm to compute such comprehensive border bases from comprehensive Gr\\\\\\\"{o}bner bases.\",\n \"Title: Algorithms for Synthesizing Safe Sets of Operation for Embedded Systems\\nYear: 2009\\n\\nAbstract: A large number of embedded computing systems are modeled as hybrid system with both discrete and continuous dynamics. In this paper, we present algorithms for analyzing nonlinear time-invariant continuous-time systems by employing reachability algorithms. We propose synthesis algorithms for finding sets of initial states for the continuous dynamical systems so that temporal properties, such as safety and liveness properties, are satisfied. The initial sets produced by the algorithms are related to some classical concepts for continuous dynamical systems, such as invariant sets and domains of attraction.\",\n \"Title: Investigating a novel GA-based feature selection method using improved KNN classifiers\\nYear: 2011\\n\\nAbstract: This paper presents a novel scheme to select a subset of features from a dataset. We apply genetic algorithm (GA) with a random small subset of features. The GA explores stochastically a better subset of features using various combinations of lengths and features over a number of generations. The classification accuracy due to different classifiers in presence of these subsets of features is taken as the performance criteria (objective function) of GA. The proposed scheme is tested on a few UCI datasets. The performances of the KNN, informative KNN (local LI-KNN and global GI-KNN), and LI-KNN with boosting in presence of all features and those in presence of only selected subset of features are compared with reported results. With extensive simulation study, it is observed that the proposed scheme produces a reasonably good accuracy with a reduced subset of features in these datasets.\",\n \"Title: Autonomic Healing of Model-Based Systems.\\nYear: 2011\\n\\nAbstract: Embedded computing is an area in which many of the self-* properties of autonomic systems are desirable. Model-based tools for designing embedded systems, while proven successful in many applications, are not yet applicable toward building autonomic or self-sustaining embedded systems. This is, in part, due to the domain-specific nature of modeling tools used to design and deploy embedded systems. The approach outlined in this paper uses a model-driven healing process to direct the system's adaptation in such a way that the resulting system configurations satisfy their particular domain-specific needs. A method for reducing the computational complexity of this healing process is also given.\",\n \"Title: Architecting Health Management into Software Component Assemblies: Lessons Learned from the ARINC-653 Component Mode\\nYear: 2012\\n\\nAbstract: Complex real-time software systems require an active fault management capability. While testing, verification and validation schemes and their constant evolution help improve the dependability of these systems, an active fault management strategy is essential to potentially mitigate the unacceptable behaviors at run-time. In our work we have applied the experience gained from the field of Systems Health Management towards component-based software systems. The software components interact via well-defined concurrency patterns and are executed on a real-time component framework built upon ARINC-653 platform services. In this paper, we present the lessons learned in architecting and applying a two-level health management strategy to assemblies of software components.\",\n \"Title: Distributed and Managed: Research Challenges and Opportunities of the Next Generation Cyber-Physical Systems\\nYear: 2014\\n\\nAbstract: Cyber-physical systems increasingly rely on distributed computing platforms where sensing, computing, actuation, and communication resources are shared by a multitude of applications. Such 'cyber-physical cloud computing platforms' present novel challenges because the system is built from mobile embedded devices, is inherently distributed, and typically suffers from highly fluctuating connectivity among the modules. Architecting software for these systems raises many challenges not present in traditional cloud computing. Effective management of constrained resources and application isolation without adversely affecting performance are necessary. Autonomous fault management and real-time performance requirements must be met in a verifiable manner. It is also both critical and challenging to support multiple end-users whose diverse software applications have changing demands for computational and communication resources, while operating on different levels and in separate domains of security. The solution presented in this paper is based on a layered architecture consisting of a novel operating system, a middleware layer, and component-structured applications. The component model facilitates the construction of software applications from modular and reusable components that are deployed in the distributed system and interact only through well-defined mechanisms. The complexity of creating applications and performing system integration is mitigated through the use of a domain-specific model-driven development process that relies on a domain-specific modeling language and its accompanying graphical modeling tools, software generators for synthesizing infrastructure code, and the extensive use of model-based analysis for verification and validation.\",\n \"Title: A Real-Time Component Framework: Experience with CCM and ARINC-653\\nYear: 2010\\n\\nAbstract: The complexity of software in systems like aerospace vehicles has reached the point where new techniques are needed to ensure system dependability while improving the productivity of developers. One possible approach is to use precisely defined software execution platforms that (1) enable the system to be composed from separate components, (2) restrict component interactions and prevent fault propagation, and (3) whose compositional properties are well-known. In this paper we describe the initial steps towards building a platform that combines component-based software construction with hard real-time operating system services. Specifically, the paper discusses how the CORBA Component Model (CCM) could be combined with the ARINC-653 platform services and the lessons learned from this experiment. The results point towards both extending the CCM as well as revising the ARINC-653.\",\n \"Title: DREMS ML: A wide spectrum architecture design language for distributed computing platforms\\nYear: 2015\\n\\nAbstract: Complex sensing, processing and control applications running on distributed platforms are difficult to design, develop, analyze, integrate, deploy and operate, especially if resource constraints, fault tolerance and security issues are to be addressed. While technology exists today for engineering distributed, real-time component-based applications, many problems remain unsolved by existing tools. Model-driven development techniques are powerful, but there are very few existing and complete tool chains that offer an end-to-end solution to developers, from design to deployment. There is a need for an integrated model-driven development environment that addresses all phases of application lifecycle including design, development, verification, analysis, integration, deployment, operation and maintenance, with supporting automation in every phase. Arguably, a centerpiece of such a model-driven environment is the modeling language. To that end, this paper presents a wide-spectrum architecture design language called DREMS ML that itself is an integrated collection of individual domain-specific sub-languages. We claim that the language promotes “correct-by-construction” software development and integration by supporting each individual phase of the application lifecycle. Using a case study, we demonstrate how the design of DREMS ML impacts the development of embedded systems.\",\n \"Title: CHARIOT: a domain specific language for extensible cyber-physical systems.\\nYear: 2015\\n\\nAbstract: Wider adoption, availability and ubiquity of wireless networking technologies, integrated sensors, actuators, and edge computing devices is facilitating a paradigm shift by allowing us to transition from traditional statically configured vertical silos of Cyber-Physical Systems (CPS) to next generation CPS that are more open, dynamic and extensible. Fractionated spacecraft, smart cities computing architectures, Unmanned Aerial Vehicle (UAV) clusters are all examples of extensible CPS wherein extensibility is implied by the dynamic aggregation of physical resources, affect of physical dynamics on availability of computing resources, and various multi-domain applications hosted on these systems. However, realization of extensible CPS requires resolving design-time and runtime challenges emanating from properties specific to these systems. In this paper, we first describe different properties of extensible CPS - dynamism, extensibility, remote deployment, security, heterogeneity and resilience. Then we identify different design-time challenges stemming from heterogeneity and resilience requirements. We particularly focus on software heterogeneity arising from availability of various communication middleware. We then present appropriate solutions in the context of a novel domain specific language and describe how this language and its features have evolved from our past work.\",\n \"Title: Analysis, verification, and management toolsuite for cyber-physical applications on time-varying networks\\nYear: 2014\\n\\nAbstract: Cyber-Physical Systems (CPS) are increasingly utilizing advances in wireless mesh networking among computing nodes to facilitate communication and control for distributed applications. Factors such as interference or node mobility cause such wireless networks to experience changes in both topology and link capacities. These dynamic networks pose a reliability concern for high-criticality or mixed-criticality systems which require strict guarantees about system performance and robustness prior to deployment. To address the design- and run-time verification and reliability concerns created by these dynamic networks, we are developing an integrated modeling, analysis, and run-time toolsuite which provides (1) network profiles that model the dynamics of system network resources and application network requirements over time, (2) design-time verification of application performance on dynamic networks, and (3) management of the CPS network resources during run-time. In this paper we present the foundations for the analysis of dynamic networks and show experimental validations of this analysis. We conclude with a focus on future work and applications to the field.\",\n \"Title: WiP Abstract: Platform for Designing and Managing Resilient and Extensible CPS\\nYear: 2016\\n\\nAbstract: Extensible Cyber-Physical Systems (CPS) are loosely connected, multi-domain platforms that \\\"virtualize\\\" their resources to provide an open platform capable of hosting different cyber-physical applications. These cyber- physical platforms are extensible since resources and applications can be added or removed at any time. However, realizing such platform requires resolving challenges emanating from different properties; for this paper, we focus on resilience. Resilience is important for extensible CPS to make sure that extensibility of a system doesn't result in failures and anomalies.\",\n \"Title: Poster Abstract: Distributed Reasoning for Diagnosing Cascading Outages in Cyber Physical Energy Systems\\nYear: 2016\\n\\nAbstract: The power grid incorporates a number of protection elements such as distance relays that detect faults and prevent the propagation of failure effects from influencing the rest of system. However, the decision of these protection elements is only influenced by local information in the form of bus voltage/current (V-I) samples. Due to lack of system wide perspective, erroneous settings, and latent failure modes, protection devices often mis-operate and cause cascading effects that ultimately lead to blackouts. Blackouts around the world have been triggered or worsened by circuit breakers tripping, including the blackout of 2003 in North America, where the secondary/ remote protection relays incorrectly opened the breaker. Tools that aid the operators in finding the root cause of the problem on-line are required. However, high system complexity and the interdependencies between the cyber and physical elements of the system and the mis-operation of protection devices make the failure diagnosis a challenging problem.\",\n \"Title: Designing a Resilient Deployment and Reconfiguration Infrastructure for Remotely Managed Cyber-Physical Systems.\\nYear: 2016\\n\\nAbstract: Multi-module Cyber-Physical Systems (CPS), such as satellite clusters, swarms of Unmanned Aerial Vehicles (UAV), and fleets of Unmanned Underwater Vehicles (UUV) provide a CPS cluster-as-a- service for CPS applications. The distributed and remote nature of these systems often necessitates the use of Deployment and Configuration (D&C) services to manage the lifecycle of these applications. Fluctuating resources, volatile cluster membership and changing environmental conditions necessitate resilience. Thus, the D&C infrastructure does not only have to undertake basic management actions, such as activation of new applications and deactivation of existing applications, but also has to autonomously reconfigure existing applications to mitigate failures including D&C infrastructure failures. This paper describes the design and architectural considerations to realize such a D&C infrastructure for component-based distributed systems. Experimental results demonstrating the autonomous resilience capabilities are presented.\",\n \"Title: The Role of Context and Resilient Middleware in Next Generation Smart Grids.\\nYear: 2016\\n\\nAbstract: The emerging trends of volatile distributed energy resources and micro-grids are putting pressure on electrical power system infrastructure. This pressure is motivating the integration of digital technology and advanced power-industry practices to improve the management of distributed electricity generation, transmission, and distribution, thereby creating a web of systems. Unlike legacy power system infrastructure, however, this emerging next-generation smart grid should be context-aware and adaptive to enable the creation of applications needed to enhance grid robustness and efficiency. This paper describes key factors that are driving the architecture of smart grids and describes orchestration middleware needed to make the infrastructure resilient. We use an example of adaptive protection logic in smart grid substations as a use case to motivate the need for contextawareness and adaptivity.\",\n \"Title: Delayradar: A Multivariate Predictive Model For Transit Systems\\nYear: 2016\\n\\nAbstract: Effective public transit operations are one of the fundamental requirements for a modern community. Recently, a number of transit agencies have started integrating automated vehicle locators in their fleet, which provides a real-time estimate of the time of arrival. In this paper, we use the data collected over several months from one such transit system and show how this data can be potentially used to learn long term patterns of travel time. More specifically, we study the effect of weather and other factors such as traffic on the transit system delay. These models can later be used to understand the seasonal variations and to design adaptive and transient transit schedules. Towards this goal, we also propose an online architecture called DelayRadar. The novelty of DelayRadar lies in three aspects: (1) a data store that collects and integrates real-time and static data from multiple data sources, (2) a predictive statistical model that analyzes the data to make predictions on transit travel time, and (3) a decision making framework to develop an optimal transit schedule based on variable forecasts related to traffic, weather, and other impactful factors. This paper focuses on identifying the model with the best predictive accuracy to be used in DelayRadar. According to the preliminary study results, we are able to explain more than 70% of the variance in the bus travel time and we can make future travel predictions with an out-of-sample error of 4.8 minutes with information on the bus schedule, traffic, and weather.\",\n \"Title: Achieving resilience in distributed software systems via self-reconfiguration.\\nYear: 2016\\n\\nAbstract: We describe resilient operation of cyber-physical application platforms.We describe implicit design-time encoding of the reconfiguration.We describe design-time analysis and validation tools for these systems. Improvements in mobile networking combined with the ubiquitous availability and adoption of low-cost development boards have enabled the vision of mobile platforms of Cyber-Physical Systems (CPS), such as fractionated spacecraft and UAV swarms. Computation and communication resources, sensors, and actuators that are shared among different applications characterize these systems. The cyber-physical nature of these systems means that physical environments can affect both the resource availability and software applications that depend on resource availability. While many application development and management challenges associated with such systems have been described in existing literature, resilient operation and execution have received less attention. This paper describes our work on improving runtime support for resilience in mobile CPS, with a special focus on our runtime infrastructure that provides autonomous resilience via self-reconfiguration. We also describe the interplay between this runtime infrastructure and our design-time tools, as the later is used to statically determine the resilience properties of the former. Finally, we present a use case study to demonstrate and evaluate our design-time resilience analysis and runtime self-reconfiguration infrastructure.\",\n \"Title: Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems.\\nYear: 2016\\n\\nAbstract: In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems.\",\n \"Title: Optimal Detection of Faulty Traffic Sensors Used in Route Planning.\\nYear: 2017\\n\\nAbstract: In a smart city, real-time traffic sensors may be deployed for various applications, such as route planning. Unfortunately, sensors are prone to failures, which result in erroneous traffic data. Erroneous data can adversely affect applications such as route planning, and can cause increased travel time. To minimize the impact of sensor failures, we must detect them promptly and accurately. However, typical detection algorithms may lead to a large number of false positives (i.e., false alarms) and false negatives (i.e., missed detections), which can result in suboptimal route planning. In this paper, we devise an effective detector for identifying faulty traffic sensors using a prediction model based on Gaussian Processes. Further, we present an approach for computing the optimal parameters of the detector which minimize losses due to false-positive and false-negative errors. We also characterize critical sensors, whose failure can have high impact on the route planning application. Finally, we implement our method and evaluate it numerically using a real- world dataset and the route planning platform OpenTripPlanner.\",\n \"Title: Poster Abstract: A Distributed and Resilient Platform for City-Scale Smart Systems\\nYear: 2016\\n\\nAbstract: The advent of the Internet of Things (IoT) is driving several technological trends. The first trend is an increased level of integration between edge devices and commodity computers. This trend, in conjunction with low power-devices, energy harvesting, and improved battery technology, is enabling the next generation of information technology (IT) innovation: city-scale smart systems. These types of IoT systems can operate at multiple time-scales, ranging from closed-loop control requiring strict real-time decision and actuation to near real-time operation with humans-in-the-loop, as well as to long-term analysis, planning, and decision-making.\",\n \"Title: Demo Abstract: RIAPS — A Resilient Information Architecture Platform for Edge Computing\\nYear: 2016\\n\\nAbstract: The emerging CPS/IoT ecosystem platforms such as Beaglebone Black, Raspberry Pi, Intel Edison and other edge devices such as SCALE, Paradrop are providing new capabilities for data collection, analysis and processing at the edge (also referred to as Fog Computing). This allows the dynamic composition of computing and communication networks that can be used to monitor and control the physical phenomena closer to the physical system. However, there are still a number of challenges that exist and must be resolved before we see wider applicability of these platforms for applications in safety-critical application domains such as Smart Grid and Traffic Control.\",\n \"Title: Resilience at the edge in cyber-physical systems\\nYear: 2017\\n\\nAbstract: As the number of low cost computing devices at the edge of communication network increase, there are greater opportunities to enable innovative capabilities, especially in cyber-physical systems. For example, micro-grid power systems can make use of computing capabilities at the edge of a Smart Grid to provide more robust and decentralized control. However, the downside to distributing intelligence to the edge away from the controlled environment of the data centers is the increased risk of failures. The paper introduces a framework for handling these challenges. The contribution of this framework is to support strategies to (a) tolerate the transient faults as they appear due to network fluctuations or node failures, and to (b) systematically reconfigure the application if the faults persist.\",\n \"Title: Prioritized Allocation of Emergency Responders based on a Continuous-Time Incident Prediction Model.\\nYear: 2017\\n\\nAbstract: Efficient emergency response is a major concern in densely populated urban areas. Numerous techniques have been proposed to allocate emergency responders to optimize response times, coverage, and incident prevention. Effective response depends, in turn, on effective prediction of incidents occurring in space and time, a problem which has also received considerable prior attention. We formulate a non-linear mathematical program maximizing expected incident coverage, and propose a novel algorithmic framework for solving this problem. In order to aid the optimization problem, we propose a novel incident prediction mechanism. Prior art in incident prediction does not generally consider incident priorities which are crucial in optimal dispatch, and spatial modeling either considers each discretized area independently, or learns a homogeneous model. We bridge these gaps by learning a joint distribution of both incident arrival time and severity, with spatial heterogeneity captured using a hierarchical clustering approach. Moreover, our decomposition of the joint arrival and severity distributions allows us to independently learn the continuous-time arrival model, and subsequently use a multinomial logistic regression to capture severity, conditional on incident time. We use real traffic accident and response data from the urban area around Nashville, USA, to evaluate the proposed approach, showing that it significantly outperforms prior art as well as the real dispatch method currently in use.\",\n \"Title: RIAPS: Resilient Information Architecture Platform for Decentralized Smart Systems\\nYear: 2017\\n\\nAbstract: The emerging Fog Computing paradigm provides an additional computational layer that enables new capabilities in real-time data-driven applications. This is especially interesting in the domain of Smart Grid as the boundaries between traditional generation, distribution, and consumer roles are blurring. This is a reflection of the ongoing trend of intelligence distribution in Smart Systems. In this paper, we briefly describe a component-based decentralized software platform called Resilient Information Architecture Platform for Smart Systems (RIAPS) which provides an infrastructure for such systems. We briefly describe some initial applications built using this platform. Then, we focus on the design and integration choices for a resilient Discovery Manager service that is a critical component of this infrastructure. The service allows applications to discover each other, work collaboratively, and ensure the stability of the Smart System.\",\n \"Title: Short Paper: Towards Low-Cost Indoor Localization Using Edge Computing Resources\\nYear: 2017\\n\\nAbstract: Emerging smart services, such as indoor smart parking or patient monitoring and tracking in hospitals, incur a significant technical roadblock stemming primarily from a lack of cost-effective and easily deployable localization framework that impedes their widespread deployment. To address this concern, in this paper we present a low-cost, indoor localization and navigation system, which performs continuous and real-time processing of Bluetooth Low Energy (BLE) and IEEE 802.15.4a compliant Ultra-wideband (UWB) sensor data to localize and navigate the concerned entity to its desired location. Our approach depends upon fusing the two feature sets, using the UWB to calibrate the BLE localization mechanism.\",\n \"Title: SpeedPro: A Predictive Multi-Model Approach for Urban Traffic Speed Estimation\\nYear: 2017\\n\\nAbstract: Data generated by GPS-equipped probe vehicles, especially public transit vehicles can be a reliable source for traffic speed estimation. Traditionally, this estimation is done by learning the parameters of a model that describes the relationship between the speed of the probe vehicle and the actual traffic speed. However, such approaches typically suffer from data sparsity issues. Furthermore, most state of the art approaches does not consider the effect of weather and the driver of the probe vehicle on the parameters of the learned model. In this paper, we describe a multivariate predictive multi-model approach called SpeedPro that (a) first identifies similar clusters of operation from the historic data that includes the real-time position of the probe vehicle, the weather data, and anonymized driver identifier, and then (b) uses these different models to estimate the traffic speed in real-time as a function of current weather, driver and probe vehicle speed. When the real-time information is not available our approach uses a different model that uses the historical weather and traffic information for estimation. Our results show that the purely historical data is less accurate than the model that uses the real-time information.\",\n \"Title: Unsupervised Mechanisms For Optimizing On-Time Performance Of Fixed Schedule Transit Vehicles\\nYear: 2017\\n\\nAbstract: The on-time arrival performance of vehicles at stops is a critical metric for both riders and city planners to evaluate the reliability of a transit system. However, it is a non-trivial task for transit agencies to adjust the existing bus schedule to optimize the on-time performance for the future. For example, severe weather conditions and special events in the city could slow down traffic and cause bus delay. Furthermore, the delay of previous trips may affect the initial departure time of consecutive trips and generate accumulated delay. In this paper, we formulate the problem as a single-objective optimization task with constraints and propose a greedy algorithm and a genetic algorithm to generate bus schedules at timepoints that improve the bus on-time performance at timepoints which is indicated by whether the arrival delay is within the desired range. We use the Nashville bus system as a case study and simulate the optimization performance using historical data. The comparative analysis of the results identifies that delay patterns change over time and reveals the efficiency of the greedy and genetic algorithms.\",\n \"Title: Indicator frameworks.\\nYear: 2017\\n\\nAbstract: We develop a diagrammatic tool for constructing correlations between random variables, called an abstract indicator framework. Abstract indicator frameworks are modeled off operational (key performance) indicator frameworks as they are used in city planning and project governance, and give a rigorous, statistically-motivated process for constructing operational indicator frameworks.\",\n \"Title: Transactive energy demo with RIAPS platform.\\nYear: 2017\\n\\nAbstract: This work presents a platform for decentralized distributed computing called Resilient Information Architecture for the Smart Grid (RIAPS) through a transactional energy and a traffic application.\",\n \"Title: Diagnostics and prognostics using temporal causal models for cyber physical energy systems.\\nYear: 2017\\n\\nAbstract: Reliable operation of cyber-physical systems such as Power Transmission and Distribution Systems is critical for the seamless functioning of a vibrant economy. These systems consist of tightly coupled physical (energy sources, transmission and distribution lines, and loads) and computational components (protection devices, energy management systems, etc). The protection devices such as distance relays help in preventing failure propagation by isolating faulty physical components. However, these devices rely on hard thresholds and local information, often ignoring system-level effects introduced by the distributed control algorithms. This leads to scenarios wherein a local mitigation in a subsystem could trigger a larger fault cascade, possibly resulting in a blackout. Efficient models and tool that curtail such systematic failures by performing fault diagnosis and prognosis are therefore necessary.\",\n \"Title: A Systematic Approach of Identifying Optimal Load Control Actions for Arresting Cascading Failures in Power Systems\\nYear: 2017\\n\\nAbstract: Cascading outages in power networks cause blackouts which lead to huge economic and social consequences. The traditional form of load shedding is avoidable in many cases by identifying optimal load control actions. However, if there is a change in the system topology (adding or removing loads, lines etc), the calculations have to be performed again. This paper addresses this problem by providing a workflow that 1) generates system models from IEEE CDF specifications, 2) identifies a collection of blackout causing contingencies, 3) dynamically sets up an optimization problem, and 4) generates a table of mitigation strategies in terms of minimal load curtailment. We demonstrate the applicability of our proposed methodology by finding load curtailment actions for N-k contingencies (k = 1, 2, 3) in IEEE 14 Bus system.\",\n \"Title: On the Design of Communication and Transaction Anonymity in Blockchain-Based Transactive Microgrids.\\nYear: 2017\\n\\nAbstract: Transactive microgrids are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation, such as wind and solar power. Distributed ledgers have recently found widespread interest in this domain due to their ability to provide transactional integrity across decentralized computing nodes. However, the existing state of the art has not focused on the privacy preservation requirement of these energy systems - the transaction level data can provide much greater insights into a prosumer's behavior compared to smart meter data. There are specific safety requirements in transactive microgrids to ensure the stability of the grid and to control the load. To fulfil these requirements, the distribution system operator needs transaction information from the grid, which poses a further challenge to the privacy goals. In this paper, we extend a recently developed trading workflow called PETra and describe our solution for communication and transactional anonymity.\",\n \"Title: Providing Privacy, Safety, and Security in IoT-Based Transactive Energy Systems using Distributed Ledgers.\\nYear: 2017\\n\\nAbstract: Power grids are undergoing major changes due to rapid growth in renewable energy resources and improvements in battery technology. While these changes enhance sustainability and efficiency, they also create significant management challenges as the complexity of power systems increases. To tackle these challenges, decentralized Internet-of-Things (IoT) solutions are emerging, which arrange local communities into transactive microgrids. Within a transactive microgrid, prosumers (i.e., consumers with energy generation and storage capabilities) can trade energy with each other, thereby smoothing the load on the main grid using local supply. It is hard, however, to provide security, safety, and privacy in a decentralized and transactive energy system. On the one hand, prosumersu0027 personal information must be protected from their trade partners and the system operator. On the other hand, the system must be protected from careless or malicious trading, which could destabilize the entire grid. This paper describes Privacy-preserving Energy Transactions (PETra), which is a secure and safe solution for transactive microgrids that enables consumers to trade energy without sacrificing their privacy. PETra builds on distributed ledgers, such as blockchains, and provides anonymity for communication, bidding, and trading.\",\n \"Title: Privacy-Preserving Platform for Transactive Energy Systems.\\nYear: 2017\\n\\nAbstract: Transactive energy systems (TES) are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation. These, on one hand, pose a decentralized power system controls problem, requiring strategic microgrid control to maintain stability for the community and for the utility. On the other hand, they require robust financial markets operating on distributed software platforms that preserve privacy. In this paper, we describe the implementation of a novel, blockchain-based transactive energy system. We outline the key requirements and motivation of this platform, describe the lessons learned, and provide a description of key architectural components of this system.\",\n \"Title: DREMS-OS: An Operating System for Managed Distributed Real-Time Embedded Systems\\nYear: 2017\\n\\nAbstract: Distributed real-time and embedded (DRE) systems executing mixed criticality task sets are increasingly being deployed in mobile and embedded cloud computing platforms, including space applications. These DRE systems must not only operate over a range of temporal and spatial scales, but also require stringent assurances for secure interactions between the system's tasks without violating their individual timing constraints. To address these challenges, this paper describes a novel distributed operating system focusing on the scheduler design to support the mixed criticality task sets. Empirical results from experiments involving a case study of a cluster of satellites emulated in a laboratory testbed validate our claims.\",\n \"Title: Time synchronization services for low-cost fog computing applications.\\nYear: 2017\\n\\nAbstract: This paper presents the time synchronization infrastructure for a low-cost run-time platform and application framework specifically targeting Smart Grid applications. Such distributed applications require the execution of reliable and accurate time-coordinated actions and observations both within islands of deployments and across geographically distant nodes. The time synchronization infrastructure is built on well-established technologies: GPS, NTP, PTP, PPS and Linux with real-time extensions, running on low-cost BeagleBone Black hardware nodes. We describe the architecture, implementation, instrumentation approach, performance results and present an example from the application domain. Also, we discuss an important finding on the effect of the Linux RT_PREEMPT real-time patch on the accuracy of the PPS subsystem and its use for GPS-based time references.\",\n \"Title: Towards a Socially Optimal Multi-Modal Routing Platform.\\nYear: 2018\\n\\nAbstract: The increasing rate of urbanization has added pressure on the already constrained transportation networks in our communities. Ride-sharing platforms such as Uber and Lyft are becoming a more commonplace, particularly in urban environments. While such services may be deemed more convenient than riding public transit due to their on-demand nature, reports show that they do not necessarily decrease the congestion in major cities. One of the key problems is that typically mobility decision support systems focus on individual utility and react only after congestion appears. In this paper, we propose socially considerate multi-modal routing algorithms that are proactive and consider, via predictions, the shared effect of riders on the overall efficacy of mobility services. We have adapted the MATSim simulator framework to incorporate the proposed algorithms present a simulation analysis of a case study in Nashville, Tennessee that assesses the effects of our routing models on the traffic congestion for different levels of penetration and adoption of socially considerate routes. Our results indicate that even at a low penetration (social ratio), we are able to achieve an improvement in system-level performance.\",\n \"Title: SolidWorx: A Resilient and Trustworthy Transactive Platform for Smart and Connected Communities.\\nYear: 2018\\n\\nAbstract: Internet of Things and data sciences are fueling the development of innovative solutions for various applications in Smart and Connected Communities (SCC). These applications provide participants with the capability to exchange not only data but also resources, which raises the concerns of integrity, trust, and above all the need for fair and optimal solutions to the problem of resource allocation. This exchange of information and resources leads to a problem where the stakeholders of the system may have limited trust in each other. Thus, collaboratively reaching consensus on when, how, and who should access certain resources becomes problematic. This paper presents SolidWorx, a blockchain-based platform that provides key mechanisms required for arbitrating resource consumption across different SCC applications in a domain-agnostic manner. For example, it introduces and implements a hybrid-solver pattern, where complex optimization computation is handled off-blockchain while solution validation is performed by a smart contract. To ensure correctness, the smart contract of SolidWorx is generated and verified using a model-based approach.\",\n \"Title: Towards an architecture for evaluating and analyzing decentralized Fog applications\\nYear: 2017\\n\\nAbstract: As the number of low cost computing devices at the edge of network increases, there are greater opportunities to enable novel, innovative capabilities, especially in decentralized cyber-physical systems. For example, in an urban setting, a set of networked, collaborating processors at the edge can be used to dynamically detect traffic densities via image processing and then use those densities to control the traffic flow by coordinating traffic light sequences, in a decentralized architecture. In this paper we describe a testbed and an application framework for such applications.\",\n \"Title: Performance evaluation of smart systems under uncertainty\\nYear: 2017\\n\\nAbstract: This paper develops a model-based framework for the quantification and propagation of multiple uncertainty sources affecting the performance of a smart system. A smart system, in general, performs sensing, control and actuation for proper functioning of a physical subsystem (also referred to as a plant). With strong feedback coupling between several subsystems, the uncertainty in the quantities of interest (QoI) amplifies over time. The coupling in a generic smart system occurs at two levels: (1) coupling between individual subsystems (plant, cyber, actuation, sensors), and (2) coupling between nodes in a distributed computational subsystem. In this paper, a coupled smart system is decoupled and considered as a feed-forward system over time and modeled using a two-level Dynamic Bayesian Network (DBN), one at each level of coupling (between subsystems and between nodes). A DBN can aggregate uncertainty from multiple sources within a time step and across time steps. The DBN associated with a smart system can be learned using available system models, physics models and data. The proposed methodology is demonstrated for the design of a smart indoor heating system (identification of sensors and a wireless network) within cost constraints that enables room-by-room temperature control. We observe that sensor uncertainty has a higher impact on the performance of the heating system compared to the uncertainty in the wireless network.\",\n \"Title: Mobilytics- An Extensible, Modular and Resilient Mobility Platform\\nYear: 2018\\n\\nAbstract: Transportation management platforms provide communities the ability to integrate the available mobility options and localized transportation demand management policies. A central component of a transportation management platform is the mobility planning application. Given the societal relevance of these platforms, it is necessary to ensure that they operate resiliently. Modularity and extensibility are also critical properties that are required for manageability. Modularity allows to isolate faults easily. Extensibility enables update of policies and integration of new mobility modes or new routing algorithms. However, state of the art mobility planning applications like open trip planner, are monolithic applications, which makes it difficult to scale and modify them dynamically. This paper describes a microservices based modular multi-modal mobility platform Mobilytics, that integrates mobility providers, commuters, and community stakeholders. We describe our requirements, architecture, and discuss the resilience challenges, and how our platform functions properly in presence of failure. Conceivably, the patterns and principles manifested in our system can serve as guidelines for current and future practitioners in this field.\",\n \"Title: Short-Term Transit Decision Support System Using Multi-task Deep Neural Networks\\nYear: 2018\\n\\nAbstract: Unpredictability is one of the top reasons that prevent people from using public transportation. To improve the on-time performance of transit systems, prior work focuses on updating schedule periodically in the long-term and providing arrival delay prediction in real-time. But when no real-time transit and traffic feed is available (e.g., one day ahead), there is a lack of effective contextual prediction mechanism that can give alerts of possible delay to commuters. In this paper, we propose a generic tool-chain that takes standard General Transit Feed Specification (GTFS) transit feeds and contextual information (recurring delay patterns before and after big events in the city and the contextual information such as scheduled events and forecasted weather conditions) as inputs and provides service alerts as output. Particularly, we utilize shared route segment networks and multi-task deep neural networks to solve the data sparsity and generalization issues. Experimental evaluation shows that the proposed toolchain is effective at predicting severe delay with a relatively high recall of 76% and F1 score of 55%.\",\n \"Title: CHARIOT: Goal-Driven Orchestration Middleware for Resilient IoT Systems.\\nYear: 2018\\n\\nAbstract: An emerging trend in Internet of Things (IoT) applications is to move the computation (cyber) closer to the source of the data (physical). This paradigm is often referred to as edge computing. If edge resources are pooled together, they can be used as decentralized shared resources for IoT applications, providing increased capacity to scale up computations and minimize end-to-end latency. Managing applications on these edge resources is hard, however, due to their remote, distributed, and (possibly) dynamic nature, which necessitates autonomous management mechanisms that facilitate application deployment, failure avoidance, failure management, and incremental updates. To address these needs, we present CHARIOT, which is orchestration middleware capable of autonomously managing IoT systems consisting of edge resources and applications.\\n\\nCHARIOT implements a three-layer architecture. The topmost layer comprises a system description language, the middle layer comprises a persistent data storage layer and the corresponding schema to store system information, and the bottom layer comprises a management engine that uses information stored persistently to formulate constraints that encode system properties and requirements, thereby enabling the use of satisfiability modulo theory solvers to compute optimal system (re)configurations dynamically at runtime. This article describes the structure and functionality of CHARIOT and evaluates its efficacy as the basis for a smart parking system case study that uses sensors to manage parking spaces.\",\n \"Title: A Data-driven Prognostic Architecture for Online Monitoring of Hard Disks Using Deep LSTM Networks.\\nYear: 2018\\n\\nAbstract: With the advent of pervasive cloud computing technologies, service reliability and availability are becoming major concerns,especially as we start to integrate cyber-physical systems with the cloud networks. A number of smart and connected community systems such as emergency response systems utilize cloud networks to analyze real-time data streams and provide context-sensitive decision support.Improving overall system reliability requires us to study all the aspects of the end-to-end of this distributed system,including the backend data servers. In this paper, we describe a bi-layered prognostic architecture for predicting the Remaining Useful Life (RUL) of components of backend servers,especially those that are subjected to degradation. We show that our architecture is especially good at predicting the remaining useful life of hard disks. A Deep LSTM Network is used as the backbone of this fast, data-driven decision framework and dynamically captures the pattern of the incoming data. In the article, we discuss the architecture of the neural network and describe the mechanisms to choose the various hyper-parameters. We describe the challenges faced in extracting effective training sets from highly unorganized and class-imbalanced big data and establish methods for online predictions with extensive data pre-processing, feature extraction and validation through test sets with unknown remaining useful lives of the hard disks. Our algorithm performs especially well in predicting RUL near the critical zone of a device approaching failure.The proposed architecture is able to predict whether a disk is going to fail in next ten days with an average precision of 0.8435.In future, we will extend this architecture to learn and predict the RUL of the edge devices in the end-to-end distributed systems of smart communities, taking into consideration context-sensitive external features such as weather.\",\n \"Title: Introducing the new paradigm of Social Dispersed Computing: Applications, Technologies and Challenges.\\nYear: 2018\\n\\nAbstract: If last decade viewed computational services as a utilitythen surely this decade has transformed computation into a commodity. Computation is now progressively integrated into the physical networks in a seamless way that enables cyber-physical systems (CPS) and the Internet of Things (IoT) meet their latency requirements. Similar to the concept of “platform as a service” or “software as a service”, both cloudlets and fog computing have found their own use cases. Edge devices (that we call end or user devices for disambiguation) play the role of personal computers, dedicated to a user and to a set of correlated applications. In this new scenario, the boundaries between the network node, the sensor, and the actuator are blurring, driven primarily by the computation power of IoT nodes like single board computers and the smartphones. The bigger data generated in this type of networks needs clever, scalable, and possibly decentralized computing solutions that can scale independently as required. Any node can be seen as part of a graph, with the capacity to serve as a computing or network router node, or both. Complex applications can possibly be distributed over this graph or network of nodes to improve the overall performance like the amount of data processed over time. In this paper, we identify this new computing paradigm that we call Social Dispersed Computing, analyzing key themes in it that includes a new outlook on its relation to agent based applications. We architect this new paradigm by providing supportive application examples that include next generation electrical energy distribution networks, next generation mobility services for transportation, and applications for distributed analysis and identification of non-recurring traffic congestion in cities. The paper analyzes the existing computing paradigms (e.g., cloud, fog, edge, mobile edge, social, etc.), solving the ambiguity of their definitions; and analyzes and discusses the relevant foundational software technologies, the remaining challenges, and research opportunities.\",\n \"Title: VeriSolid: Correct-by-Design Smart Contracts for Ethereum.\\nYear: 2019\\n\\nAbstract: The adoption of blockchain based distributed ledgers is growing fast due to their ability to provide reliability, integrity, and auditability without trusted entities. One of the key capabilities of these emerging platforms is the ability to create self-enforcing smart contracts. However, the development of smart contracts has proven to be error-prone in practice, and as a result, contracts deployed on public platforms are often riddled with security vulnerabilities. This issue is exacerbated by the design of these platforms, which forbids updating contract code and rolling back malicious transactions. In light of this, it is crucial to ensure that a smart contract is secure before deploying it and trusting it with significant amounts of cryptocurrency. To this end, we introduce the VeriSolid framework for the formal verification of contracts that are specified using a transition-system based model with rigorous operational semantics. Our model-based approach allows developers to reason about and verify contract behavior at a high level of abstraction. VeriSolid allows the generation of Solidity code from the verified models, which enables the correct-by-design development of smart contracts.\",\n \"Title: TRANSAX: A Blockchain-Based Decentralized Forward-Trading Energy Exchanged for Transactive Microgrids\\nYear: 2019\\n\\nAbstract: Power grids are undergoing major changes due to rapid growth in renewable energy and improvements in battery technology. Prompted by the increasing complexity of power systems, decentralized IoT solutions are emerging, which arrange local communities into transactive microgrids. The core functionality of these solutions is to provide mechanisms for matching producers with consumers while ensuring system safety. However, there are multiple challenges that these solutions still face: privacy, trust, and resilience. The privacy challenge arises because the time series of production and consumption data for each participant is sensitive and may be used to infer personal information. Trust is an issue because a producer or consumer can renege on the promised energy transfer. Providing resilience is challenging due to the possibility of failures in the infrastructure that is required to support these market based solutions. In this paper, we develop a rigorous solution for transactive microgrids that addresses all three challenges by providing an innovative combination of MILP solvers, smart contracts, and publish-subscribe middleware within a framework of a novel distributed application platform, called Resilient Information Architecture Platform for Smart Grid. Towards this purpose, we describe the key architectural concepts, including fault tolerance, and show the trade-off between market efficiency and resource requirements,\",\n \"Title: Incident Analysis And Prediction Using Clustering And Bayesian Network\\nYear: 2017\\n\\nAbstract: Advances in data collection and storage infrastructure offer an unprecedented opportunity to integrate both data and emergency resources in a city into a dynamic learning system that can anticipate and rapidly respond to heterogeneous incidents. In this paper, we describe integration methods for spatio-temporal incident forecasting using previously collected vehicular accident data provided to us by the Nashville Fire Department. The literature provides several techniques that focus on analyzing features and predicting accidents for specific situations (specific intersections in a city, or certain segments of a freeway, for example), but these models break down when applied to a large, general area consisting of many road and intersection types and other factors like weather conditions. We use Similarity Based Agglomerative Clustering (SBAC) analysis to categorize incidents to account for these variables. Thereafter, we use survival analysis to learn the likelihood of incidents per cluster. The mapping of the clusters to the spatial locations is achieved using a Bayesian network. The prediction methods we have developed lay the foundation for future work on an optimal emergency vehicle allocation and dispatch system in Nashville.\",\n \"Title: PlaTIBART: a platform for transactive IoT blockchain applications with repeatable testing.\\nYear: 2017\\n\\nAbstract: With the advent of blockchain-enabled IoT applications, there is an increased need for related software patterns, middleware concepts, and testing practices to ensure adequate quality and productivity. IoT and blockchain each provide different design goals, concepts, and practices that must be integrated, including the distributed actor model and fault tolerance from IoT and transactive information integrity over untrustworthy sources from blockchain. Both IoT and blockchain are emerging technologies and both lack codified patterns and practices for development of applications when combined. This paper describes PlaTIBART, which is a platform for transactive IoT blockchain applications with repeatable testing that combines the Actor pattern (which is a commonly used model of computation in IoT) together with a custom Domain Specific Language (DSL) and test network management tools. We show how PlaTIBART has been applied to develop, test, and analyze fault-tolerant IoT blockchain applications.\",\n \"Title: Transit-hub: a smart public transportation decision support system with multi-timescale analytical services\\nYear: 2019\\n\\nAbstract: Public transit is a critical component of a smart and connected community. As such, citizens expect and require accurate information about real-time arrival/departures of transportation assets. As transit agencies enable large-scale integration of real-time sensors and support back-end data-driven decision support systems, the dynamic data-driven applications systems (DDDAS) paradigm becomes a promising approach to make the system smarter by providing online model learning and multi-time scale analytics as part of the decision support system that is used in the DDDAS feedback loop. In this paper, we describe a system in use in Nashville and illustrate the analytic methods developed by our team. These methods use both historical as well as real-time streaming data for online bus arrival prediction. The historical data is used to build classifiers that enable us to create expected performance models as well as identify anomalies. These classifiers can be used to provide schedule adjustment feedback to the metro transit authority. We also show how these analytics services can be packaged into modular, distributed and resilient micro-services that can be deployed on both cloud back ends as well as edge computing resources.\",\n \"Title: Device Access Abstractions for Resilient Information Architecture Platform for Smart Grid\\nYear: 2019\\n\\nAbstract: This letter presents an overview of design mechanisms to abstract device access protocols in the resilient information architecture platform for smart grid, a middleware for developing distributed smart grid applications. These mechanisms are required to decouple the application functionality from the specifics of the device mechanisms built by the device vendors.\",\n \"Title: Supporting Fog/Edge-Based Cognitive Assistance Iot Services For The Visually Mpaired\\nYear: 2019\\n\\nAbstract: The fog/edge computing paradigm is increasingly being adopted to support a variety of latency-sensitive IoT services, such as cognitive assistance to the visually impaired, due to its ability to assure the latency requirements of these services while continuing to benefit from the elastic properties of cloud computing. However, user mobility in such applications imposes a new set of challenges that must be addressed before such applications can be deployed and benefit the society. This paper presents ongoing work on a dynamic resource management middleware called URMILA that addresses these concerns. URMILA ensures that the service remains available despite user mobility and ensuing wireless connectivity issues by opportunistically leveraging both fog and edge resources in such a way that the latency requirements of the service are met while ensuring longevity of the battery life on the edge devices. We present the design principles of URMILA's capabilities and a real-world cognitive assistance application that we have built and are testing on an emulated but realistic IoT testbed.\",\n \"Title: An online decision-theoretic pipeline for responder dispatch.\\nYear: 2019\\n\\nAbstract: The problem of dispatching emergency responders to service traffic accidents, fire, distress calls and crimes plagues urban areas across the globe. While such problems have been extensively looked at, most approaches are offline. Such methodologies fail to capture the dynamically changing environments under which critical emergency response occurs, and therefore, fail to be implemented in practice. Any holistic approach towards creating a pipeline for effective emergency response must also look at other challenges that it subsumes - predicting when and where incidents happen and understanding the changing environmental dynamics. We describe a system that collectively deals with all these problems in an online manner, meaning that the models get updated with streaming data sources. We highlight why such an approach is crucial to the effectiveness of emergency response, and present an algorithmic framework that can compute promising actions for a given decision-theoretic model for responder dispatch. We argue that carefully crafted heuristic measures can balance the trade-off between computational time and the quality of solutions achieved and highlight why such an approach is more scalable and tractable than traditional approaches. We also present an online mechanism for incident prediction, as well as an approach based on recurrent neural networks for learning and predicting environmental features that affect responder dispatch. We compare our methodology with prior state-of-the-art and existing dispatch strategies in the field, which show that our approach results in a reduction in response time with a drastic reduction in computational time.\",\n \"Title: Incident management and analysis dashboard for fire departments - ICCPS demo.\\nYear: 2019\\n\\nAbstract: This work presents a dashboard tool that helps emergency responders analyze and manage spatial-temporal incidents like crime and traffic accidents. It uses state-of-the-art statistical models to learn incident probabilities based on factors such as prior incidents, time and weather. The dashboard can then present historic and predicted incident distributions. It also allows responders to analyze how moving or adding depots (stations for emergency responders) affects average response times, and can make dispatching recommendations based on heuristics. Broadly, it is a one-stop tool that helps responders visualize historical data as well as plan for and respond to incidents.\",\n \"Title: A CPS toolchain for learning-based systems - demo abstract.\\nYear: 2019\\n\\nAbstract: Cyber-Physical Systems (CPS) are expected to perform tasks with ever-increasing levels of autonomy, often in highly uncertain environments. Traditional design techniques based on domain knowledge and analytical models are often unable to cope with epistemic uncertainties present in these systems. This challenge, combined with recent advances in machine learning, has led to the emergence of Learning-Enabled Components (LECs) in CPS. However, very little tool support is available for design automation of these systems. In this demonstration, we introduce an integrated toolchain for the development of CPS with LECs with support for architectural modeling, data collection, system software deployment, and LEC training, evaluation, and verification. Additionally, the toolchain supports the modeling and analysis of safety cases - a critical part of the engineering process for mission and safety critical systems.\",\n \"Title: Model-based design for CPS with learning-enabled components.\\nYear: 2019\\n\\nAbstract: Recent advances in machine learning led to the appearance of Learning-Enabled Components (LECs) in Cyber-Physical Systems. LECs are being evaluated and used for various, complex functions including perception and control. However, very little tool support is available for design automation in such systems. This paper introduces an integrated toolchain that supports the architectural modeling of CPS with LECs, but also has extensive support for the engineering and integration of LECs, including support for training data collection, LEC training, LEC evaluation and verification, and system software deployment. Additionally, the toolsuite supports the modeling and analysis of safety cases - a critical part of the engineering process for mission and safety critical systems.\",\n \"Title: Towards demand-oriented flexible rerouting of public transit under uncertainty.\\nYear: 2019\\n\\nAbstract: This paper proposes a flexible rerouting strategy for the public transit to accommodate the spatio-temporal variation in the travel demand. Transit routes are typically static in nature, i.e., the buses serve well-defined routes; this results in people living in away from the bus routes choose alternate transit modes such as private automotive vehicles resulting in ever-increasing traffic congestion. In the flex-transit mode, we reroute the buses to accommodate high travel demand areas away from the static routes considering its spatio-temporal variation. We perform clustering to identify several flex stops; these are stops not on the static routes, but with high travel demand around them. We divide the bus stops on the static routes into critical and non-critical bus stops; critical bus stops refer to transfer points, where people change bus routes to reach their destinations. In the existing static scheduling process, some slack time is provided at the end of each trip to account for any travel delays. Thus, the additional travel time incurred due to taking flexible routes is constrained to be less than the available slack time. We use the percent increase in travel demand to analyze the effectiveness of the rerouting process. The proposed methodology is demonstrated using real-world travel data for Route 7 operated by the Nashville Metropolitan Transit Authority (MTA).\",\n \"Title: Cyber-physical simulation platform for security assessment of transactive energy systems\\nYear: 2019\\n\\nAbstract: Transactive energy systems (TES) are emerging as a transformative solution for the problems that distribution system operators face due to an increase in the use of distributed energy resources and rapid growth in scalability of managing active distribution system (ADS). On the one hand, these changes pose a decentralized power system control problem, requiring strategic control to maintain reliability and resiliency for the community and for the utility. On the other hand, they require robust financial markets while allowing participation from diverse prosumers. To support the computing and flexibility requirements of TES while preserving privacy and security, distributed software platforms are required. In this paper, we enable the study and analysis of security concerns by developing Transactive Energy Security Simulation Testbed (TESST), a TES testbed for simulating various cyber attacks. In this work, the testbed is used for TES simulation with centralized clearing market, highlighting weaknesses in a centralized system. Additionally, we present a blockchain enabled decentralized market solution supported by distributed computing for TES, which on one hand can alleviate some of the problems that we identify, but on the other hand, may introduce newer issues. Future study of these differing paradigms is necessary and will continue as we develop our security simulation testbed.\",\n \"Title: Augmenting Learning Components for Safety in Resource Constrained Autonomous Robots\\nYear: 2019\\n\\nAbstract: Learning enabled components (LECs) trained using data-driven algorithms are increasingly being used in autonomous robots commonly found in factories, hospitals, and educational laboratories. However, these LECs do not provide any safety guarantees, and testing them is challenging. In this paper, we introduce a framework that performs weighted simplex strategy based supervised safety control, resource management and confidence estimation of autonomous robots. Specifically, we describe two weighted simplex strategies: (a) simple weighted simplex strategy (SW-Simplex) that computes a weighted controller output by comparing the decisions between a safety supervisor and an LEC, and (b) a context-sensitive weighted simplex strategy (CSW-Simplex) that computes a context-aware weighted controller output. We use reinforcement learning to learn the contextual weights. We also introduce a system monitor that uses the current state information and a Bayesian network model learned from past data to estimate the probability of the robotic system staying in the safe working region. To aid resource constrained robots in performing complex computations of these weighted simplex strategies, we describe a resource manager that offloads tasks to an available fog nodes. The paper also describes a hardware testbed called DeepNNCar, which is a low cost resource-constrained RC car, built to perform autonomous driving. Using the hardware, we show that both SW-Simplex and CSW-Simplex have 40% and 60% fewer safety violations, while demonstrating higher optimized speed during indoor driving (~ 0.40 m/s) than the original system (using only LECs).\",\n \"Title: Towards an Adaptive Multi-Modal Traffic Analytics Framework at the Edge\\nYear: 2019\\n\\nAbstract: The Internet of Things (IoT) requires distributed, large scale data collection via geographically distributed devices. While IoT devices typically send data to the cloud for processing, this is problematic for bandwidth constrained applications. Fog and edge computing (processing data near where it is gathered, and sending only results to the cloud) has become more popular, as it lowers network overhead and latency. Edge computing often uses devices with low computational capacity, therefore service frameworks and middleware are needed to efficiently compose services. While many frameworks use a top-down perspective, quality of service is an emergent property of the entire system and often requires a bottom up approach. We define services as multi-modal, allowing resource and performance tradeoffs. Different modes can be composed to meet an application's high level goal, which is modeled as a function. We examine a case study for counting vehicle traffic through intersections in Nashville. We apply object detection and tracking to video of the intersection, which must be performed at the edge due to privacy and bandwidth constraints. We explore the hardware and software architectures, and identify the various modes. This paper lays the foundation to formulate the online optimization problem presented by the system which makes tradeoffs between the quantity of services and their quality constrained by available resources.\",\n \"Title: Demo: Transactive Energy Application with RIAPS\\nYear: 2019\\n\\nAbstract: The modern electric grid is a complex, decentralized cyber-physical system requiring higher-level control techniques to balance the demand and supply of energy to optimize the overall energy usage. The concept of Transactive Energy utilizes distributed system principle to address this challenge. In this demonstration we show the usage of the distributed application management platform RIAPS in the implementation of one such Transactive Energy approach to control elements of a power system, which runs as a a simulation using the Gridlab-d simulation solver.\",\n \"Title: DeepNNCar: A Testbed for Deploying and Testing Middleware Frameworks for Autonomous Robots\\nYear: 2019\\n\\nAbstract: This demo showcases the features of an adaptive middleware framework for resource constrained autonomous robots like DeepNNCar (Figure 1). These robots use Learning Enabled Components (LECs), trained with deep learning models to perform control actions. However, these LECs do not provide any safety guarantees and testing them is challenging. To overcome these challenges, we have developed an adaptive middleware framework that (1) augments the LEC with safety controllers that can use different weighted simplex strategies to improve the systems safety guarantees, and (2) includes a resource manager to monitor the resource parameters (temperature, CPU Utilization), and offload tasks at runtime. Using DeepNNCar we will demonstrate the framework and its capability to adaptively switch between the controllers and strategies based on its safety and speed performance.\",\n \"Title: Short Paper: Towards An Edge-Located Time-Series Database\\nYear: 2019\\n\\nAbstract: Smart infrastructure demands resilient data storage, and emerging applications execute queries on this data over time. Typically, time-series databases serve these queries; however, cloud-based time-series storage can be prohibitively expensive. As smart devices proliferate, the amount of computing power and memory available in our connected infrastructure provides the opportunity to move resilient time-series data storage and analytics to the edge. This paper proposes time-series storage in a Distributed Hash Table (DHT), and a novel key-generation technique that provides time-indexed reads and writes for key-value pairs. Experimental results show this technique meets demands for smart infrastructure situations.\",\n \"Title: On the Design of Fault- Tolerance in a Decentralized Software Platform for Power Systems\\nYear: 2019\\n\\nAbstract: The vision of the `Smart Grid' assumes a distributed real-time embedded system that implements various monitoring and control functions. As the reliability of the power grid is critical to modern society, the software supporting the grid must support fault tolerance and resilience in the resulting cyber-physical system. This paper describes the fault-tolerance features of a software framework called Resilient Information Architecture Platform for Smart Grid (RIAPS). The framework supports various mechanisms for fault detection and mitigation and works in concert with the applications that implement the grid-specific functions. The paper discusses the design philosophy for and the implementation of the fault tolerance features and presents an application example to show how it can be used to build highly resilient systems.\",\n \"Title: Analyzing The Cascading Effect Of Traffic Congestion Using Lstm Networks\\nYear: 2019\\n\\nAbstract: This paper presents a data-driven approach for predicting the propagation of traffic congestion at road segments as a function of the congestion in their neighboring segments. In the past, this problem has mostly been addressed by modelling the traffic congestion over some standard physical phenomenon through which it is difficult to capture all the modalities of such a dynamic and complex system. While other recent works have focused on applying a generalized data-driven technique on the whole network at once, they often ignore intersection characteristics. On the contrary, we propose a citywide ensemble of intersection level connected LSTM models and propose mechanisms for identifying congestion events using the predictions from the networks. To reduce the search space of likely congestion sinks we use the likelihood of congestion propagation in neighboring road segments of a congestion source that we learn from the past historical data. We validated our congestion forecasting framework on the real world traffic data of Nashville, USA and identified the onset of congestion in each of the neighboring segments of any congestion source with an average precision of 0.9269 and an average recall of 0.9118 tested over ten congestion events.\",\n \"Title: Cyber-Attacks and Mitigation in Blockchain Based Transactive Energy Systems\\nYear: 2020\\n\\nAbstract: Power grids are undergoing major changes due to the rapid adoption of intermittent renewable energy resources and the increased availability of energy storage devices. These trends drive smart-grid operators to envision a future where peer-to-peer energy trading occurs within microgrids, leading to the development of Transactive Energy Systems. Blockchains have garnered significant interest from both academia and industry for their potential application in decentralized TES, in large part due to their high level of resilience. In this paper, we introduce a novel class of attacks against blockchain based TES, which target the gateways that connect market participants to the system. We introduce a general model of blockchain based TES and study multiple threat models and attack strategies. We also demonstrate the impact of these attacks using a testbed based on GridLAB-D and a private Ethereum network. Finally, we study how to mitigate these attack.\",\n \"Title: TRANSIT-GYM: A Simulation and Evaluation Engine for Analysis of Bus Transit Systems\\nYear: 2021\\n\\nAbstract: Public-transit systems face a number of operational challenges: (a) changing ridership patterns requiring optimization of fixed line services, (b) optimizing vehicle-to-trip assignments to reduce maintenance and operation codes, and (c) ensuring equitable and fair coverage to areas with low ridership. Optimizing these objectives presents a hard computational problem due to the size and complexity ...\",\n \"Title: Energy and Emission Prediction for Mixed-Vehicle Transit Fleets Using Multi-task and Inductive Transfer Learning\\nYear: 2021\\n\\nAbstract: Public transit agencies are focused on making their fixed-line bus systems more energy efficient by introducing electric (EV) and hybrid (HV) vehicles to their fleets. However, because of the high upfront cost of these vehicles, most agencies are tasked with managing a mixed-fleet of internal combustion vehicles (ICEVs), EVs, and HVs. In managing mixed-fleets, agencies require accurate predictions of energy use for optimizing the assignment of vehicles to transit routes, scheduling charging, and ensuring that emission standards are met. The current state-of-the-art is to develop separate neural network models to predict energy consumption for each vehicle class. Although different vehicle classes' energy consumption depends on a varied set of covariates, we hypothesize that there are broader generalizable patterns that govern energy consumption and emissions. In this paper, we seek to extract these patterns to aid learning to address two problems faced by transit agencies. First, in the case of a transit agency which operates many ICEVs, HVs, and EVs, we use multi-task learning (MTL) to improve accuracy of forecasting energy consumption. Second, in the case where there is a significant variation in vehicles in each category, we use inductive transfer learning (ITL) to improve predictive accuracy for vehicle class models with insufficient data. As this work is to be deployed by our partner agency, we also provide an online pipeline for joining the various sensor streams for fixed-line transit energy prediction. We find that our approach outperforms vehicle-specific baselines in both the MTL and ITL settings.\",\n \"Title: User-centric Distributed Route Planning in Smart Cities based on Multi-objective Optimization\\nYear: 2021\\n\\nAbstract: The realization of edge-based cyber-physical systems (CPS) poses important challenges in terms of performance, robustness, security, etc. This paper examines a novel approach to providing a user-centric adaptive route planning service over a network of Road Side Units (RSUs) in smart cities. The key idea is to adaptively select routing task parameters such as privacy-cloaked area sizes and number ...\",\n \"Title: Learning Incident Prediction Models Over Large Geographical Areas for Emergency Response\\nYear: 2021\\n\\nAbstract: Emergency Response Management (ERM) necessitates the use of models capable of predicting the spatial-temporal likelihood of incident occurrence. These models are used for proactive stationing in order to reduce overall response time. Traditional methods simply aggregate past incidents over space and time; such approaches fail to make useful short-term predictions when the spatial region is large a...\",\n \"Title: Power-attack: a comprehensive tool-chain for modeling and simulating attacks in power systems\\nYear: 2021\\n\\nAbstract: ABSTRACTDue to the increased deployment of novel communication, control and protection functions, the grid has become vulnerable to a variety of attacks. Designing robust machine learning based attack detection and mitigation algorithms require large amounts of data that rely heavily on a representative environment, where different attacks can be simulated. This paper presents a comprehensive tool-chain for modeling and simulating attacks in power systems. The paper makes the following contributions, first, we present a probabilistic domain specific language to define multiple attack scenarios and simulation configuration parameters. Secondly, we extend the PyPower-dynamics simulator with protection system components to simulate cyber attacks in control and protection layers of power system. In the end, we demonstrate multiple attack scenarios with a case study based on IEEE 39 bus system.\",\n \"Title: RT-METER: a real-time, multi-layer cyber-power testbed for resiliency analysis\\nYear: 2021\\n\\nAbstract: ABSTRACTIn this work, we present a Real-Time, Multi-layer cybEr-power TestbEd for the Resiliency analysis (RT-METER) to support power grid operation and planning. Developed cyber-power testbed provides a mechanism for end-to-end validation of advanced tools for cyber-power grid monitoring, control, and planning. By integrating a host of features across three core layers-physical power system, communication network, and monitoring/control center with advanced tools,---the testbed provides a platform to model and simulate rich and diverse cyber-power grid scenarios and generating realistic sensors, system, and network data. These data are subsequently used in validating advanced tools to assist operators during complex and challenging scenarios, which is essential for the successful operation of the future grid. We detail a suite of algorithmic tools validated using the developed testbed and the generated realistic grid data.\",\n \"Title: Data-Driven Prediction and Optimization of Energy Use for Transit Fleets of Electric and ICE Vehicles\\nYear: 2022\\n\\nAbstract: AbstractDue to the high upfront cost of electric vehicles, many public transit agencies can afford only mixed fleets of internal combustion and electric vehicles. Optimizing the operation of such mixed fleets is challenging because it requires accurate trip-level predictions of electricity and fuel use as well as efficient algorithms for assigning vehicles to transit routes. We present a novel framework for the data-driven prediction of trip-level energy use for mixed-vehicle transit fleets and for the optimization of vehicle assignments, which we evaluate using data collected from the bus fleet of CARTA, the public transit agency of Chattanooga, TN. We first introduce a data collection, storage, and processing framework for system-level and high-frequency vehicle-level transit data, including domain-specific data cleansing methods. We train and evaluate machine learning models for energy prediction, demonstrating that deep neural networks attain the highest accuracy. Based on these predictions, we formulate the problem of minimizing energy use through assigning vehicles to fixed-route transit trips. We propose an optimal integer program as well as efficient heuristic and meta-heuristic algorithms, demonstrating the scalability and performance of these algorithms numerically using the transit network of CARTA.\",\n \"Title: Practitioner-Centric Approach for Early Incident Detection Using Crowdsourced Data for Emergency Services\\nYear: 2021\\n\\nAbstract: Emergency response is highly dependent on the time of incident reporting. Unfortunately, the traditional approach to receiving incident reports (e.g., calling 911 in the USA) has time delays. Crowdsourcing platforms such as Waze provide an opportunity for early identification of incidents. However, detecting incidents from crowdsourced data streams is difficult due to the challenges of noise and uncertainty associated with such data. Further, simply optimizing over detection accuracy can compromise spatial-temporal localization of the inference, thereby making such approaches infeasible for real-world deployment. This paper presents a novel problem formulation and solution approach for practitioner-centered incident detection using crowdsourced data by using emergency response management as a case-study. The proposed approach CROME (Crowdsourced Multi-objective Event Detection) quantifies the relationship between the performance metrics of incident classification (e.g., F1 score) and the requirements of model practitioners (e.g., 1 km. radius for incident detection). First, we show how crowdsourced reports, ground-truth historical data, and other relevant determinants such as traffic and weather can be used together in a Convolutional Neural Network (CNN) architecture for early detection of emergency incidents. Then, we use a Pareto optimization-based approach to optimize the output of the CNN in tandem with practitioner-centric parameters to balance detection accuracy and spatial-temporal localization. Finally, we demonstrate the applicability of this approach using crowdsourced data from Waze and traffic accident reports from Nashville, TN, USA. Our experiments demonstrate that the proposed approach outperforms existing approaches in incident detection while simultaneously optimizing the needs for real-world deployment and usability.\",\n \"Title: Automated Method for Assurance Case Construction from System Design Models\\nYear: 2021\\n\\nAbstract: Many Cyber Physical Systems (CPSs) operate in safety- or mission-critical applications where strong assurance of safe operation is required. Assurance cases are one widely used tool for presenting an argument in support of system safety requirements backed by a body of evidence - e.g., test data, formal analysis, or expert review. A system assurance case should regularly evolve during the developm...\",\n \"Title: Risk-Aware Scene Sampling for Dynamic Assurance of Autonomous Systems\\nYear: 2022\\n\\nAbstract: Autonomous Cyber-Physical Systems must often operate under uncertainties like sensor degradation and shifts in the operating conditions, which increases its operational risk. Dynamic Assurance of these systems requires designing runtime safety components like Out-of-Distribution detectors and risk estimators, which require labeled data from different operating modes of the system that belong to sc...\",\n \"Title: An Online Approach to Solve the Dynamic Vehicle Routing Problem with Stochastic Trip Requests for Paratransit Services\\nYear: 2022\\n\\nAbstract: Many transit agencies operating paratransit and microtransit ser-vices have to respond to trip requests that arrive in real-time, which entails solving hard combinatorial and sequential decision-making problems under uncertainty. To avoid decisions that lead to signifi-cant inefficiency in the long term, vehicles should be allocated to requests by optimizing a non-myopic utility function or by batching requests together and optimizing a myopic utility function. While the former approach is typically offline, the latter can be performed online. We point out two major issues with such approaches when applied to paratransit services in practice. First, it is difficult to batch paratransit requests together as they are temporally sparse. Second, the environment in which transit agencies operate changes dynamically (e.g., traffic conditions can change over time), causing the estimates that are learned offline to become stale. To address these challenges, we propose a fully online approach to solve the dynamic vehicle routing problem (DVRP) with time windows and stochastic trip requests that is robust to changing environmental dynamics by construction. We focus on scenarios where requests are relatively sparse-our problem is motivated by applications to paratransit services. We formulate DVRP as a Markov decision process and use Monte Carlo tree search to evaluate actions for any given state. Accounting for stochastic requests while optimizing a non-myopic utility function is computationally challenging; indeed, the action space for such a problem is intractably large in practice. To tackle the large action space, we leverage the structure of the problem to design heuristics that can sample promising actions for the tree search. Our experiments using real-world data from our partner agency show that the proposed approach outperforms existing state-of-the-art approaches both in terms of performance and robustness.\",\n \"Title: Offline Vehicle Routing Problem with Online Bookings: A Novel Problem Formulation with Applications to Paratransit.\\nYear: 2022\\n\\nAbstract: Vehicle routing problems (VRPs) can be divided into two major categories: offline VRPs, which consider a given set of trip requests to be served, and online VRPs, which consider requests as they arrive in real-time. Based on discussions with public transit agencies, we identify a real-world problem that is not addressed by existing formulations: booking trips with flexible pickup windows (e.g., 3 hours) in advance (e.g., the day before) and confirming tight pickup windows (e.g., 30 minutes) at the time of booking. Such a service model is often required in paratransit service settings, where passengers typically book trips for the next day over the phone. To address this gap between offline and online problems, we introduce a novel formulation, the offline vehicle routing problem with online bookings. This problem is very challenging computationally since it faces the complexity of considering large sets of requests -- similar to offline VRPs -- but must abide by strict constraints on running time -- similar to online VRPs. To solve this problem, we propose a novel computational approach, which combines an anytime algorithm with a learning-based policy for real-time decisions. Based on a paratransit dataset obtained from our partner transit agency, we demonstrate that our novel formulation and computational approach lead to significantly better outcomes in this service setting than existing algorithms.\",\n \"Title: ADVISER: AI-Driven Vaccination Intervention Optimiser for Increasing Vaccine Uptake in Nigeria.\\nYear: 2022\\n\\nAbstract: More than 5 million children under five years die from largely preventable or treatable medical conditions every year, with an overwhelmingly large proportion of deaths occurring in under-developed countries with low vaccination uptake. One of the United Nations' sustainable development goals (SDG 3) aims to end preventable deaths of newborns and children under five years of age. We focus on Nigeria, where the rate of infant mortality is appalling. We collaborate with HelpMum, a large non-profit organization in Nigeria to design and optimize the allocation of heterogeneous health interventions under uncertainty to increase vaccination uptake, the first such collaboration in Nigeria. Our framework, ADVISER: AI-Driven Vaccination Intervention Optimiser, is based on an integer linear program that seeks to maximize the cumulative probability of successful vaccination. Our optimization formulation is intractable in practice. We present a heuristic approach that enables us to solve the problem for real-world use-cases. We also present theoretical bounds for the heuristic method. Finally, we show that the proposed approach outperforms baseline methods in terms of vaccination uptake through experimental evaluation. HelpMum is currently planning a pilot program based on our approach to be deployed in the largest city of Nigeria, which would be the first deployment of an AI-driven vaccination uptake program in the country and hopefully, pave the way for other data-driven programs to improve health outcomes in Nigeria.\",\n \"Title: Moving target defense for the security and resilience of mixed time and event triggered cyber–physical systems\\nYear: 2022\\n\\nAbstract: Memory corruption attacks such as code injection, code reuse, and non-control data attacks have become widely popular for compromising safety-critical Cyber–Physical Systems (CPS). Moving target defense (MTD) techniques such as instruction set randomization (ISR), address space randomization (ASR), and data space randomization (DSR) can be used to protect systems against such attacks. CPS often use time-triggered architectures to guarantee predictable and reliable operation. MTD techniques can cause time delays with unpredictable behavior. To protect CPS against memory corruption attacks, MTD techniques can be implemented in a mixed time and event-triggered architecture that provides capabilities for maintaining safety and availability during an attack. This paper presents a mixed time and event-triggered MTD security approach based on the ARINC 653 architecture that provides predictable and reliable operation during normal operation and rapid detection and reconfiguration upon detection of attacks. We leverage a hardware-in-the-loop testbed and an advanced emergency braking system (AEBS) case study to show the effectiveness of our approach.\",\n \"Title: Syntheto: A Surface Language for APT and ACL2.\\nYear: 2022\\n\\nAbstract: Syntheto is a surface language for carrying out formally verified program synthesis by transformational refinement in ACL2 using the APT toolkit. Syntheto aims at providing more familiarity and automation, in order to make this technology more widely usable. Syntheto is a strongly statically typed functional language that includes both executable and non-executable constructs, including facilities to state and prove theorems and facilities to apply proof-generating transformations. Syntheto is integrated into an IDE with a notebook-style, interactive interface that translates Syntheto to ACL2 definitions and APT transformation invocations, and back-translates the prover's results to Syntheto; the bidirectional translation happens behind the scenes, with the user interacting solely with Syntheto.\",\n \"Title: ANTI-CARLA: An Adversarial Testing Framework for Autonomous Vehicles in CARLA.\\nYear: 2022\\n\\nAbstract: Despite recent advances in autonomous driving systems, accidents such as the fatal Uber crash in 2018 show these systems are still susceptible to edge cases. Such systems must be thoroughly tested and validated before being deployed in the real world to avoid such events. Testing in open-world scenarios can be difficult, time-consuming, and expensive. These challenges can be addressed by using driving simulators such as CARLA instead. A key part of such tests is adversarial testing, in which the goal is to find scenarios that lead to failures of the given system. While several independent efforts in testing have been made, a well-established testing framework that enables adversarial testing has yet to be made available for CARLA. We therefore propose ANTI-CARLA, an automated testing framework in CARLA for simulating adversarial weather conditions (e.g., heavy rain) and sensor faults (e.g., camera occlusion) that fail the system. The operating conditions in which a given system should be tested are specified in a scenario description language. The framework offers an efficient search mechanism that searches for adversarial operating conditions that will fail the tested system. In this way, ANTI-CARLA extends the CARLA simulator with the capability of performing adversarial testing on any given driving pipeline. We use ANTI-CARLA to test the driving pipeline trained with Learning By Cheating (LBC) approach. The simulation results demonstrate that ANTI-CARLA can effectively and automatically find a range of failure cases despite LBC reaching an accuracy of 100% in the CARLA benchmark.\",\n \"Title: Anomaly based Incident Detection in Large Scale Smart Transportation Systems\\nYear: 2022\\n\\nAbstract: Modern smart cities are focusing on smart transportation solutions to detect and mitigate the effects of various traffic incidents in the city. To materialize this, roadside units and ambient trans-portation sensors are being deployed to collect vehicular data that provides real-time traffic monitoring. In this paper, we first propose a real-time data-driven anomaly-based traffic incident detection framework for a city-scale smart transportation system. Specifically, we propose an incremental region growing approximation algorithm for optimal Spatio-temporal clustering of road segments and their data; such that road segments are strategically divided into highly correlated clusters. The highly correlated clusters enable identifying a Pythagorean Mean-based invariant as an anomaly detection metric that is highly stable under no incidents but shows a deviation in the presence of incidents. We learn the bounds of the invariants in a robust manner such that anomaly detection can generalize to unseen events, even when learning from real noisy data. We perform extensive experimental validation using mobility data collected from the City of Nashville, Tennessee, and prove that the method can detect incidents within each cluster in real-time.\",\n \"Title: Neural Architecture and Feature Search for Predicting the Ridership of Public Transportation Routes\\nYear: 2022\\n\\nAbstract: Accurately predicting the ridership of public-transit routes provides substantial benefits to both transit agencies, who can dispatch additional vehicles proactively before the vehicles that serve a route become crowded, and to passengers, who can avoid crowded vehicles based on publicly available predictions. The spread of the coronavirus disease has further elevated the importance of ridership prediction as crowded vehicles now present not only an inconvenience but also a public-health risk. At the same time, accurately predicting ridership has become more challenging due to evolving ridership patterns, which may make all data except for the most recent records stale. One promising approach for improving prediction accuracy is to fine-tune the hyper-parameters of machine-learning models for each transit route based on the characteristics of the particular route, such as the number of records. However, manually designing a machine-learning model for each route is a labor-intensive process, which may require experts to spend a significant amount of their valuable time. To help experts with designing machine-learning models, we propose a neural-architecture and feature search approach, which optimizes the architecture and features of a deep neural network for predicting the ridership of a public-transit route. Our approach is based on a randomized local hyper-parameter search, which minimizes both prediction error as well as the complexity of the model. We evaluate our approach on real-world ridership data provided by the public transit agency of Chattanooga, TN, and we demonstrate that training neural networks whose architectures and features are optimized for each route provides significantly better performance than training neural networks whose architectures and features are generic.\",\n \"Title: Automating Pattern Selection for Assurance Case Development for Cyber-Physical Systems\\nYear: 2022\\n\\nAbstract: Assurance Cases are increasingly being required for regulatory acceptance of Cyber-Physical Systems. However, the ever-increasing complexity of these systems has made the assurance cases development complex, labor-intensive and time-consuming. Assurance case fragments called patterns are used to handle the complexity. The state-of-the-art approach has been to manually select generic patterns from online catalogs, instantiate them with system-specific information, and assemble them into an assurance case. While there has been some work in automating the instantiation and assembly, a less researched area is the automation of the pattern selection process, which takes a considerable amount of the assurance case development time. To close this automation gap, we have developed an automated pattern selection workflow that handles the selection problem as a coverage problem, intending to find the smallest set of patterns that can cover the available system artifacts. For this, we utilize the ontology graphs of the system artifacts and the patterns and perform graph analytics. The selected patterns are fed into an external instantiation function to develop an assurance case. Then, they are evaluated for coverage using two coverage metrics. An illustrative autonomous vehicle example is provided, demonstrating the utility of the proposed workflow in developing an assurance case with reduced efforts and time compared to the manual development alternative.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":96,"string":"96"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":60,"string":"60"}}},{"rowIdx":61,"cells":{"question_id":{"kind":"string","value":"Padma Raghavan"},"question":{"kind":"string","value":"Generate an abstract for the title \"Scalable parallel graph partitioning\" using the following items: 1. Parallel graph partitioning\n2. Multilevel partitioners\n3. Coordinate bisection schemes\n4. Scalable parallel scheme\n5. Lattice-based multilevel embedding"},"answer":{"kind":"string","value":"We consider partitioning a graph in parallel using a large number of processors. Parallel multilevel partitioners, such as Pt-Scotch and ParMetis, produce good quality partitions but their performance scales poorly. Coordinate bisection schemes such as those in Zoltan, which can be applied only to graphs with coordinates, scale well but partition quality is often compromised. We seek to address this gap by developing a scalable parallel scheme which imparts coordinates to a graph through a lattice-based multilevel embedding. Partitions are computed with a parallel formulation of a geometric scheme that has been shown to provide provably good cuts on certain classes of graphs. We analyze the parallel complexity of our scheme and we observe speed-ups and cut-sizes on large graphs. Our results indicate that our method is substantially faster than ParMetis and Pt-Scotch for hundreds to thousands of processors, while producing high quality cuts."},"correct_answer":{"kind":"string","value":"We consider partitioning a graph in parallel using a large number of processors. Parallel multilevel partitioners, such as Pt-Scotch and ParMetis, produce good quality partitions but their performance scales poorly. Coordinate bisection schemes such as those in Zoltan, which can be applied only to graphs with coordinates, scale well but partition quality is often compromised. We seek to address this gap by developing a scalable parallel scheme which imparts coordinates to a graph through a lattice-based multilevel embedding. Partitions are computed with a parallel formulation of a geometric scheme that has been shown to provide provably good cuts on certain classes of graphs. We analyze the parallel complexity of our scheme and we observe speed-ups and cut-sizes on large graphs. Our results indicate that our method is substantially faster than ParMetis and Pt-Scotch for hundreds to thousands of processors, while producing high quality cuts."},"documents":{"kind":"list like","value":["Title: A new data-mapping scheme for latency-tolerant distributed sparse triangular solution\nYear: 2002\n\nAbstract: This paper concerns latency-tolerant schemes for the efficient parallel solution of sparse triangular linear systems on distributed memory multiprocessors. Such triangular solution is required when sparse Cholesky factors are used to solve for a sequence of right-hand-side vectors or when incomplete sparse Cholesky factors are used to precondition a Conjugate Gradients iterative solver. In such applications, the use of traditional distributed substitution schemes can create a performance bottleneck when the latency of interprocessor communication is large. We had earlier developed the Selective Inversion (SI) scheme to reduce communication latency costs by replacing distributed substitution by parallel matrix vector multiplication. We now present a new two-way mapping of the triangular sparse matrix to processors to improve the performance of SI by halving its communication latency costs. We provide analytic results for model sparse matrices and we report on the performance of our scheme for parallel preconditioning with incomplete sparse Cholesky factors.","Title: Load Miss Prediction - Exploiting Power Performance Trade-offs\nYear: 2007\n\nAbstract: Modern CPUs operate at GHz frequencies, but the latencies of memory accesses are still relatively large, in the order of hundreds of cycles. Deeper cache hierarchies with larger cache sizes can mask these latencies for codes with good data locality and reuse, such as structured dense matrix computations. However, cache hierarchies do not necessarily benefit sparse scientific computing codes, which tend to have limited data locality and reuse. We therefore propose a new memory architecture with a Load Miss Predictor (LMP), which includes a data bypass cache and a predictor table, to reduce access latencies by determining whether a load should bypass the main cache hierarchy and issue an early load to main memory. Our architecture uses the L2 (and lower caches) as a victim cache for data removed from our bypass cache. We use cycle- accurate simulations, with SimpleScalar and Wattch to show that our LMP improves the performance of sparse codes, our application domain of interest, on average by 14%, with a 13.6% increase in power. When the LMP is used with dynamic voltage and frequency scaling (DVFS), performance can be improved by 8.7% with system power savings of 7.3% and energy reduction of 17.3% at 1800MHz relative to the base system at 2000MHz. Alternatively our LMP can be used to improve the performance of SPEC benchmarks by an average of 2.9% at the cost of 7.1% increase in average power.","Title: Performance of a Fully Parallel Sparse Solver.\nYear: 1997\n\nAbstract: The performance of a fully parallel direct solver for large sparse-symmetric positive definite systems of linear equations is demonstrated. The solver is designed for distributed-memory, message-passing parallel computer systems. All phases of the computation, including sym bolic processing as well as numeric factorization and triangular solution, are performed in parallel. A parallel Cartesian-nested dissection algorithm is used to compute a fill- reducing ordering for the matrix and an appropriate partitioning of the problem across the processors. The separator tree resulting from nested dissection is used to identify and exploit large-grain parallelism in the remaining steps of the computation. The parallel performance of the solver is reported for a series of test problems on the Thinking Machines CM-5 and the Intel Touchstone Delta. The parallel efficiency, scalability, and absolute perfor mance of the solver, as well as the relative importance of the various phases of the computation, are investigated empirically","Title: Feature subspace transformations for enhancing k-means clustering\nYear: 2010\n\nAbstract: Unsupervised classification typically concerns identifying clusters of similar entities in an unlabeled dataset. Popular methods include clustering based on (i) distance-based metrics between the entities in the feature space (K-Means), and (ii) combinatorial properties in a weighted graph representation of the dataset (Multilevel K-Means). In this paper, we present a force-directed graph layout based feature subspace transformation (FST) scheme to transform the dataset before the application of K-Means. Our FST-K-Means method utilizes both distance-based and combinatorial attributes of the original dataset to seek improvements in the internal and external quality metrics of unsupervised classification. We demonstrate the effectiveness of FST-K-Means in improving classification quality relative to K-Means and Multilevel K-Means (GraClus). The quality of classification is measured by observing internal and external quality metrics on a test suite of datasets. Our results indicate that on average, the internal quality metric (cluster cohesiveness) is 20.2% better than K-Means, and 6.6% better than GraClus. More significantly, FST-K-Means improves the external quality metric (accuracy) of classification on average by 14.9% relative to K-Means and 23.6% relative to GraClus.","Title: Multi-pass mapping schemes for parallel sparse matrix computations\nYear: 2005\n\nAbstract: Consider the solution of a large sparse linear system Ax = b on multiprocessors. A parallel sparse matrix factorization is required in a direct solver. Alternatively, if Krylov subspace iterative methods are used, then incomplete forms of parallel sparse factorization are required for preconditioning. In such schemes, the underlying parallel computation is tree-structured, utilizing task-parallelism at lower levels of the tree and data-parallelism at higher levels. The proportional heuristic has typically been used to map the data and computation to processors. However, for sparse systems from finite-element methods on complex domains, the resulting assignments can exhibit significant load-imbalances. In this paper, we develop a multi-pass mapping scheme to reduce such load imbalances and we demonstrate its effectiveness for a test suite of large sparse matrices. Our scheme can also be used to generate improved mappings for tree-structured applications beyond those considered in this paper.","Title: Adapting application execution in CMPs using helper threads\nYear: 2009\n\nAbstract: In parallel to the changes in both the architecture domain-the move toward chip multiprocessors (CMPs)-and the application domain-the move toward increasingly data-intensive workloads-issues such as performance, energy efficiency and CPU availability are becoming increasingly critical. The CPU availability can change dynamically due to several reasons such as thermal overload, increase in transient errors, or operating system scheduling. An important question in this context is how to adapt, in a CMP, the execution of a given application to CPU availability change at runtime. Our paper studies this problem, targeting the energy-delay product (EDP) as the main metric to optimize. We first discuss that, in adapting the application execution to the varying CPU availability, one needs to consider the number of CPUs to use, the number of application threads to accommodate and the voltage/frequency levels to employ (if the CMP has this capability). We then propose to use helper threads to adapt the application execution to CPU availability change in general with the goal of minimizing the EDP. The helper thread runs parallel to the application execution threads and tries to determine the ideal number of CPUs, threads and voltage/frequency levels to employ at any given point in execution. We illustrate this idea using four applications (Fast Fourier Transform, MultiGrid, LU decomposition and Conjugate Gradient) under different execution scenarios. The results collected through our experiments are very promising and indicate that significant EDP reductions are possible using helper threads. For example, we achieved up to 66.3%, 83.3%, 91.2%, and 94.2% savings in EDP when adjusting all the parameters properly in applications FFT, MG, LU, and CG, respectively. We also discuss how our approach can be extended to address multi-programmed workloads.","Title: A latency tolerant hybrid sparse solver using incomplete Cholesky factorization\nYear: 2003\n\nAbstract: Consider the solution of large sparse symmetric positive definite linear systems using the preconditioned conjugate gradient method. On sequential architectures, incomplete Cholesky factorizations provide effective preconditioning for systems from a variety of application domains, some of which may have widely differing preconditioning requirements. However, incomplete factorization based preconditioners are not considered suitable for multiprocessors. This is primarily because the triangular solution step required to apply the preconditioner (at each iteration) does not scale well due to the large latency of inter-processor communication. We propose a new approach to overcome this performance bottleneck by coupling incomplete factorization with a selective inversion scheme to replace triangular solutions by scalable matrix-vector multiplications. We discuss our algorithm, analyze its communication latency for model sparse linear systems, and provide empirical results on its performance and scalability. Copyright (C) 2003 John Wiley, Sons, Ltd.","Title: A Cartesian Parallel Nested Dissection Algorithm\nYear: 1995\n\nAbstract: This paper is concerned with the distributed parallel computation of an ordering for a symmetric positive definite sparse matrix. The purpose of the ordering is to limit fill and enhance concurrency in the subsequent Cholesky factorization of the matrix. A geometric approach to nested dissection is used based on a given Cartesian embedding of the graph of the matrix in Euclidean space. The resulting algorithm can be implemented efficiently on massively parallel, distributed memory computers. One unusual feature of the distributed algorithm is that its effectiveness does not depend on data locality, which is critical in this context, since an appropriate partitioning of the problem is not known until after the ordering has been determined. The ordering algorithm is the first component in a suite of scalable parallel algorithms currently under development for solving large sparse linear systems on massively parallel computers.","Title: Poster reception - Energy/performance modeling for collective communication in 3-D torus cluster networks\nYear: 2006\n\nAbstract: As supercomputers scale ever larger, energy consumption in interconnection networks is an emerging problem. In this work, we analyze the energy consumption and traffic patterns in a 3-D torus network in order to locate and exploit opportunities to save energy by disabling network links dynamically. Using a custom-built simulator, TorusSim, we show that, for common scientific computing codes that utilize collective communications, regularities in the network and algorithmic data flow result in many unused and under-utilized links that can be disabled to save energy at no performance cost. In the case of a reduce operation, we see that at least 56% of the links in a 4x4x4 torus network can be disabled during communication, with significant other opportunity to save energy on under-utilized links that could lead to over 80% overall link energy savings.","Title: Towards energy efficient scaling of scientific codes\nYear: 2008\n\nAbstract: Energy consumption is becoming a crucial concern within the high performance computing community as computers expand to the peta-scale and beyond. Although the peak execution rates on tuned dense matrix operations in supercomputers have consistently increased to approach the peta-scale regime, the linear scaling of peak execution rates has been achieved at the expense of cubic growth in power with systems already appearing in the megawatt range. In this paper, we extend the ideas of algorithm scalability and performance iso-efficiency to characterize the system-wide energy consumption. The latter includes dynamic and leakage energy for CPUs, memories and network interconnects. We propose analytical models for evaluating energy scalability and energy efficiency. These models are important for understanding the power consumption trends of data intensive applications executing on a large number of processors. We apply the models to two scientific applications to explore opportunities when using voltage/frequency scaling for energy savings without degrading performance. Our results indicate that such models are critical for energy-aware high-performance computing in the tera- to peta-scale regime.","Title: Advanced algorithms and software components for scientific computing: an introduction\nYear: 2004\n\nAbstract: Scientific computing concerns the design, analysis and implementation of algorithms and software to enable computational modeling and simulation across disciplines. Recent research in scientific computing has been spurred both by advances in multiprocessor systems and the wider acceptance of computational modeling as a third mode of scientific investigation, in addition in to theory and experiment. We introduce the next six chapters on advanced algorithms and software components for scientific computing on parallel computers. We review recent results toward enabling the scalable solution of large-scale modeling applications.","Title: Conjugate gradient sparse solvers: performance-power characteristics\nYear: 2006\n\nAbstract: We characterize the performance and power attributes of the conjugate gradient (CG) sparse solver which is widely used in scientific applications. We use cycle-accurate simulations with SimpleScalar and Wattch, on a processor and memory architecture similar to the configuration of a node of the BlueGene/L. We first demonstrate that substantial power savings can be obtained without performance degradation if low power modes of caches can be utilized. We next show that if Dynamic Voltage Scaling (DVS) can be used, power and energy savings are possible, but these are realized only at the expense of performance penalties. We then consider two simple memory subsystem optimizations, namely memory and level-2 cache prefetching. We demonstrate that when DVS and low power modes of caches are used with these optimizations, performance can be improved significantly with reductions in power and energy. For example, execution time is reduced by 23%, power by 55% and energy by 65% in the final configuration at 500 MHz relative to the original at 1 GHz. We also use our codes and the CG NAS benchmark code to demonstrate that performance and power profiles can vary significantly depending on matrix properties and the level of code tuning. These results indicate that architectural evaluations can benefit if traditional benchmarks are augmented with codes more representative of tuned scientific applications.","Title: A Grid Computing Environment for Enabling Large Scale Quantum Mechanical Simulations\nYear: 2000\n\nAbstract: This paper describes work-in-progress towards developing a simulation environment that utilizes recent advances in in the areas of grid middleware and computational kernels. Our goal is to develop an environment suitable for composing and deploying an overall high-performance, flexible and robust software solution for large-scale quantum mechanical simulations.","Title: Integrated link/CPU voltage scaling for reducing energy consumption of parallel sparse matrix applications\nYear: 2006\n\nAbstract: Reducing power consumption is quickly becoming a first-class optimization metric for many high-performance parallel computing platforms. One of the techniques employed by many prior proposals along this direction is voltage scaling and past research used it on different components such as networks, CPUs, and memories. In contrast to most of the existent efforts on voltage scaling that target a single component (CPU, network or memory components), this paper proposes and experimentally evaluates a voltage/frequency scaling algorithm that considers CPU and communication links in a mesh network at the same time. More specifically, it scales voltages/frequencies of both CPUs in the network and the communication links among them in a coordinated fashion (instead of one after another) such that energy savings are maximized without impacting execution time. Our experiments with several tree-based sparse matrix computations reveal that the proposed integrated voltage scaling approach is very effective in practice and brings 13% and 17% energy savings over the pure CPU and pure communication link voltage scaling schemes, respectively. The results also show that our savings are consistent with the different network sizes and different sets of voltage/frequency levels","Title: A Multilevel Cholesky Conjugate Gradients Hybrid Solver For Linear Systems With Multiple Right-Hand Sides\nYear: 2011\n\nAbstract: We consider the problem of repeatedly solving a large sparse linear system Ax = b for the same coefficient matrix A with a sequence of different right-hand side vectors b. We seek to develop a new tree-structured hybrid solver as an efficient alternative to Preconditioned Conjugate Gradients (PCG) based methods for this problem when A is symmetric positive definite and sparse.In this paper, our key contribution is a tree-based multilevel hybrid of direct and iterative methods using sparse Cholesky and PCG, respectively. Cholesky is applied to the leaf submatrices and PCG is applied to higher level subsystems in the tree. Partial solutions obtained thereafter are aggregated and corrected to provide the final solution. Our tree-based hybrid solution strategy seeks to couple the accuracy of a sparse direct solver with the memory efficiency of an iterative method to potentially improve overall performance for repeated solutions.We provide an empirical evaluation on a suite of 12 benchmark matrices from the University of Florida collection. Our results indicate that our tree-based hybrid solver is 1.87 times faster than most variants of PCG, among several, using different combinations of ordering, level-of-fill or threshold methods with an Incomplete Cholesky preconditioner.","Title: Reducing energy consumption of parallel sparse matrix applications through integrated link/CPU voltage scaling\nYear: 2007\n\nAbstract: Reducing power consumption is quickly becoming a first-class optimization metric for many high-performance parallel computing platforms. One of the techniques employed by many prior proposals along this direction is voltage scaling and past research used it on different components such as networks, CPUs, and memories. In contrast to most of the existent efforts on voltage scaling that target a single component (CPU, network or memory components), this paper proposes and experimentally evaluates a voltage/frequency scaling algorithm that considers CPU and communication links in a mesh network at the same time. More specifically, it scales voltages/frequencies of CPUs in the nodes and the communication links among them in a coordinated fashion (instead of one after another) such that energy savings are maximized without impacting execution time. Our experiments with several tree-based sparse matrix computations reveal that the proposed integrated voltage scaling approach is very effective in practice and brings 13% and 17% energy savings over the pure CPU and pure communication link voltage scaling schemes, respectively. The results also show that our savings are consistent with the different network sizes and different sets of voltage/frequency levels.","Title: Similarity Graph Neighborhoods for Enhanced Supervised Classification.\nYear: 2012\n\nAbstract: We consider transformations to enhance classification accuracy that are applied during the training phase of a supervised classifier with prelabeled data. We consider similarity graph neighborhoods (SGN) in the feature subspace of the training data to obtain a transformed dataset by determining displacements for each entity. Our SGN classifier is a supervised learning scheme that is trained on these transformed data; the separating boundary obtained is thereafter used for future classification. We discuss improvements in classification accuracy for an artificial dataset and present empirical results for Linear Discriminant (LD) classifier, Support Vector Machine (SVM), SGN-LD, and SGN-SVM for 6 well-known datasets from the University of California at Irvine (UCI) repository [1]. Our results indicate that on average SGN-LD improves accuracy by 5.0% and SGN-SVM improves it by 4.52%.","Title: Markov Model Based Disk Power Management for Data Intensive Workloads\nYear: 2009\n\nAbstract: In order to meet the increasing demands of present and upcoming data-intensive computer applications, there has been a major shift in the disk subsystem, which now consists of more disks with higher storage capacities and higher rotational speeds. These have made the disk subsystem a major consumer of power, making disk power management an important issue. People have considered the option of spinning down the disk during periods of idleness or serving the requests at lower rotational speeds when performance is not an issue. Accurately predicting future disk idle periods is crucial to such schemes. This paper presents a novel disk-idleness prediction mechanism based on Markov models and explains how this mechanism can be used in conjunction with a three-speed disk. Our experimental evaluation using a diverse set of workloads indicates that (i) prediction accuracies achieved by the proposed scheme are very good (87.5% on average); (ii) it generates significant energy savings over the traditional power-saving method of spinning down the disk when idle (35.5% onaverage); (iii) it performs better than a previously proposed multi-speed disk management scheme (19% on average); and (iv) the performance penalty is negligible (less than 1% on average). Overall, our implementation and experimental evaluation using both synthetic disk traces and traces extracted from real applications demonstrate the feasibility of a Markov-model-based approach to saving disk power.","Title: Adapting Application Mapping to Systematic Within-Die Process Variations on Chip Multiprocessors\nYear: 2009\n\nAbstract: Process variations, which lead to timing and power variations across identically-designed components, have been identified as one of the key future design challenges by the semiconductor industry. Using worst case latency/power assumptions is one option to address process variations. This option, while simplifying the problem, is becoming less and less attractive as its performance and power costs keep increasing. As a result, exploring options that allow the software to have knowledge about the actual latency/power consumption values is critical for future systems. Targeting systematic process variations, this paper makes two contributions. First, we discuss how we can assign threads to the cores of a chip multiprocessor (CMP) with process variations in mind and show the energy-delay product (EDP) benefits such a process variation-aware thread mapping can bring. Second, we study the benefits of varying the frequencies on a subset of the cores to increase EDP savings. We propose and evaluate integer linear programming based thread mapping schemes in both studies. While these schemes operate with profile data, they can be made to work with partial profiling as well with the help of curve fitting. We tested our schemes using both sequential and multi-threaded benchmarks from different suites and the results collected indicate that we can achieve EDP savings as much as 73.4%, with an average saving of 37.1% over a process variation agnostic scheme.","Title: Dynamic core partitioning for energy efficiency\nYear: 2010\n\nAbstract: Chip multiprocessors (CMPs) are expected to dominate the landscape of computer architecture in the near future. The potential performance gains that can be achieved by the use of CMPs depend, to a large extent, on how much parallelism can be extracted from applications. One effective way of utilizing CMP architectures is to execute multiple (potentially multi-threaded) applications at the same time. In this work, we propose and evaluate a dynamic (runtime) core partitioning scheme for CMPs that exploits application level information. Focusing on an optimization metric called the weighted energy-delay product gain (W-EDPG), we dynamically partition available cores across competing applications during the course of execution. This dynamic partitioning uses input from a curve fitting model to predict the best operating points for an application at runtime. It can generate nonuniform core allocations across applications (i.e., some applications may have more or fewer cores than others) if doing so increases the value of the W-EDPG metric. We compare this approach against several alternative schemes (including equal partitioning of cores and standard operating system based scheduling). Our experiments indicate that the proposed core partitioning scheme improves the W-EDPG metric significantly (e.g., 14.0% on average over the equal partitioning scheme on a 16-core CMP when four multi-threaded applications are executing concurrently).","Title: Performance of Greedy Ordering Heuristics for Sparse Cholesky Factorization\nYear: 1999\n\nAbstract: Greedy algorithms for ordering sparse matrices for Cholesky factorization can be based on different metrics. Minimum degree, a popular and effective greedy ordering scheme, minimizes the number of nonzero entries in the rank-1 update (degree) at each step of the factorization. Alternatively, minimum deficiency minimizes the number of nonzero entries introduced (deficiency) at each step of the factorization. In this paper we develop two new heuristics: modified minimum deficiency (MMDF) and modified multiple minimum degree (MMMD). The former uses a metric similar to deficiency while the latter uses a degree-like metric. Our experiments reveal that on the average, MMDF orderings result in 21% fewer operations to factor than minimum degree; MMMD orderings result in 15% fewer operations to factor than minimum degree. MMMD requires on the average 7--13% more time than minimum degree, while MMDF requires on the average 33--34% more time than minimum degree.","Title: Characterizing sparse preconditioner performance for the support vector machine kernel\nYear: 2010\n\nAbstract: A two-class Support Vector Machine (SVM) classifier finds a hyperplane that separates two classes of data with the maximum margin. In a first learning phase, SVM involves the construction and solution of a primal-dual interiorpoint optimization problem. Each iteration of the interior-point method (IPM) requires a sparse linear system solution, which dominates the execution time of SVM learning. Solving this linear system can often be computationally expensive depending on the conditioning of the matrix. Consequently, preconditioned linear systems can lead to improved SVM performance while maintaining the classification accuracy. In this paper, we seek to characterize the role of preconditioning schemes for enhancing the SVM classifier performance. We compare and report on the solution time, convergence, and number of Newton iterations of the iterior-point method and classification accuracy of the SVM for 6 well-accepted preconditioning schemes and datasets chosen from well-known machine learning repositories. In particular, we introduce Δ-IPM that sparsifies the linear system at each iteration of the IPM. Our results indicate that on average the Jacobi and SSOR preconditioners perform 10.01 times better than other preconditioning schemes for IPM and 8.83 times better for Δ-IPM. Also, across all datasets Jacobi and SSOR perform between 2 to 30 times better than other schemes in both IPM and Δ-IPM. Moreover, Δ-IPM obtains a speedup over IPM performance on average by 1.25 and as much as 2 times speedup in the best case.","Title: Co-Scheduling Algorithms for High-Throughput Workload Execution\nYear: 2013\n\nAbstract: This paper investigates co-scheduling algorithms for processing a set of parallel applications. Instead of executing each application one by one, using a maximum degree of parallelism for each of them, we aim at scheduling several applications concurrently. We partition the original application set into a series of packs, which are executed one by one. A pack comprises several applications, each of them with an assigned number of processors, with the constraint that the total number of processors assigned within a pack does not exceed the maximum number of available processors. The objective is to determine a partition into packs, and an assignment of processors to applications, that minimize the sum of the execution times of the packs. We thoroughly study the complexity of this optimization problem, and propose several heuristics that exhibit very good performance on a variety of workloads, whose application execution times model profiles of parallel scientific codes. We show that co-scheduling leads to faster workload completion time (40 % improvement on average over traditional scheduling) and to faster response times (50 % improvement). Hence, co-scheduling increases system throughput and saves energy, leading to significant benefits from both the user and system perspectives.","Title: Towards A Scalable Hybrid Sparse Solver\nYear: 2000\n\nAbstract: Consider the solution of very large, sparse linear systems, The most popular techniques can be broadly classified as either 'direct' or 'iterative', When the sparse matrix is symmetric and positive definite, direct methods use Cholesky factorization while iterative methods rely on Conjugate Gradients, Our goal is to develop a scalable and memory-efficient hybrid of the two methods that can be implemented with high efficiency on both serial and parallel computers and be suitable for a wide range of problems. We discuss our overall design with emphasis on performance and scalability issues, and report on progress to date. Copyright (C) 2000 John Wiley & Sons, Ltd.","Title: Speedup-Aware Co-Schedules For Efficient Workload Management\nYear: 2013\n\nAbstract: Many HPC systems run workloads comprising scientific simulations where the problem size is often fixed while model parameters are changed for each run. The speedup pro file of such applications can often be determined using data from previous runs. Many applications exhibit sublinear speedups and thus only incremental improvements in ex ecution time when larger numbers of processors are used. In this paper, we consider a workload of applications queued for execution and co-schedules that can exploit speedup profiles. More specifically, we seek co-schedules to reduce workload completion time (i.e., makespan), and total energy consumed by the system. Additionally, we explore how co schedules may reduce average application turnaround time and thus benefit the user. We propose speedup-aware processor partitioning (SAPP) co-scheduling schemes, including optimal and greedy variants. We show that our greedy co-schedules reduce system energy, workload makespan and average application turnaround time when compared to a base scheme that runs each application on all available processors. Our experiments demonstrate that on a system with 128 processors, on average, our SAPP-greedy co schedules can reduce makespan and turnaround time by 20% and decrease total energy consumed by 40%.","Title: Characterizing the impact of soft errors on iterative methods in scientific computing\nYear: 2011\n\nAbstract: The increase in on-chip transistor count facilitates achieving higher performance, but at the expense of higher susceptibility to soft errors. In this paper, we characterize the challenges posed by soft errors for large-scale applications representative of workloads on supercomputing systems. Such applications are typically based on the computational solution of partial differential equation models using either explicit or implicit methods. In both cases, the execution time of such applications is typically dominated by the time spent in their underlying sparse matrix vector multiplication kernel (SpMV, t ← A • y). We provide a theoretical analysis of the impact of a single soft error through its propagation by a sequence of sparse matrix vector multiplication operations. Our analysis indicates that a single soft error in some ith component of the vector y can corrupt the entire resultant vector in a relatively short sequence of SpMV operations. Additionally, the propagation pattern corresponds to the sparsity structure of the coefficient matrix A and the magnitude of the error grows non-linearly as(||Ai||2∗)k, after k SpMV operations, where, ||Ai∗||2 is the 2-norm of the ith row of A. We corroborate this analysis with empirical observations on a model heat equation using explicit method and well known sparse matrix systems (matrices from a test suite) for the implicit method using iterative solvers such as CG, PCG and SOR. Our results indicate that explicit schemes will suffer from soft error induced numerical instabilities, thus exacerbating intrinsic stability issues for such methods, that impose constraints on relative time and space step sizes. For implicit schemes, linear solver performance through widely used CG and PCG schemes, degrades by a factor as high as 200x, whereas, a stationary scheme such as SOR is inherently soft error resilient. Our results thus indicate the need for new approaches to achieve soft error resiliency in such methods and a critical evaluation of the tradeoffs among multiple metrics, including, performance, reliability and energy.","Title: Ring Data Location Prediction Scheme For Non-Uniform Cache Architectures\nYear: 2008\n\nAbstract: Increases in cache capacity are accompanied by growing wire delays due to technology scaling. Non-Uniform Cache Architecture (NUCA) is one of proposed solutions to reducing the average access latency in such cache designs. While most of the prior NUCA work focuses on data placement, data replacement, and migration related issues, this paper studies the problem of data search (access) in NUCA. In our architecture we arrange sets of banks with equal access latency into rings. Our Last Access Based (LAB) prediction scheme predicts the ring that is expected to contain the required data and checks the banks in that ring first for the data block sought. We compare our scheme to two alternate approaches: searching all rings in parallel, and searching rings sequentially. We show that our LAB ring prediction scheme reduces L2 energy significantly over the sequential and parallel schemes, while maintaining similar performance. Our LAB scheme reduces energy consumption by 15.9% relative to the sequential lookup scheme, and 53.8% relative to the parallel lookup scheme.","Title: Level search schemes for information filtering and retrieval\nYear: 2001\n\nAbstract: Latent semantic indexing (LSI) has been demonstrated to outperform lexical matching in information retrieval. However, the enormous cost associated with the singular value decomposition (SVD) of the large term-by-document matrix becomes a barrier for its application to scalable information retrieval. This work shows that information filtering using level search techniques can reduce the SVD computation cost for LSI. For each query, level search extracts a much smaller subset of the original term-by-document matrix, containing on average 27% of the original non-zero entries. When LSI is applied to such subsets, the average precision can degrade by as much as 23% due to level search filtering. However, for some document collections an increase in precision has also been observed. Further enhancement of level search can be based on a pruning scheme which deletes terms connected to only one document from the query-specific submatrix. Such pruning has achieved a 65% reduction (on average) in the number of non-zeros with a precision loss of 5% for most collections.","Title: Phase Partitioning Methods for I/O Cache Optimization\nYear: 2012\n\nAbstract: System designers face large challenges in the storage hierarchy when putting new optimizations into practice. We consider a recent storage cache optimization, designed to reduce cache requirements and boost I/O performance, which adapts to individual program behavior. This scheme leverages a quantum-based design, and we observe that the choice of time quanta has a significant effect on performance and overheads. Accordingly, intelligent designs must judiciously select re-optimization points. We therefore develop new phase detection schemes that identify valued re-optimization points through interaction models between applications and this caching technique. We evaluate online and offline variants in the context of enterprise I/O workloads and observe hit-rate gains over 20% for a range of cache sizes.","Title: Interference Resolver in Shared Storage Systems to Provide Fairness to I/O Intensive Applications\nYear: 2013\n\nAbstract: Most of the prior mechanisms on managing shared storage resources manage each individual shared resource without considering the interplay between different resources, leading to low fairness and loss of performance. Therefore, a coordinated mechanism that provides fairness in the entire shared storage system is desirable. This paper proposes a strategy to control inter-application interference by dynamically adjusting the aggressiveness of the shared storage cache and I/O bandwidth accesses made by multiple, concurrently-executing applications, in a coordinated fashion. Our interference resolver eliminates the need for complicated individual resource-based partitioning mechanisms implemented independently in each resource and that require coordination. It ensures fairness among high performance applications that access the underlying storage system, while best utilizing the available resources. In our experimental evaluation, we use both trace-driven simulations and an implementation in the Linux kernel 2.6.32, and show that our interference resolver can significantly increase system performance and provide fairness to concurrently-executing applications.","Title: Ring Prediction for Non-Uniform Cache Architectures\nYear: 2007\n\nAbstract: Increasing wire delays and memory capacities motivate new ways of designing L2 and L3 caches. NUCA (Non-Uniform Cache Architecture) has received considerable attention in the last few years. While most of the prior NUCA-based efforts have focused on data placement, data replacement, and migration related issues, this paper studies the problem of data search. Specifically, it proposes and experimentally evaluates several data search schemes for NUCA L2 caches that exhibit different performance-power trade-offs. These schemes are based on predicting the next ring (set of banks) to be accessed in a NUCA L2, and checking the banks in that ring first. In this work, we present the details of these prediction schemes, and compare them to two alternate approaches: searching all rings in parallel, and searching rings sequentially, starting with the one that is closest to the CPU.","Title: Towards Low-Cost, High-Accuracy Classifiers for Linear Solver Selection\nYear: 2009\n\nAbstract: The time to solve linear systems depends to a large extent on the choice of the solution method and the properties of the coefficient matrix. Although there are several linear solution methods, in most cases it is impossible to predict apriori which linear solver would be best suited for a given linear system. Recent investigations on selecting linear solvers for a given system have explored the use of classification techniques based on the linear system parameters for solver selection. In this paper, we present a method to develop low-cost high-accuracy classifiers. We show that the cost for constructing a classifier can be significantly reduced by focusing on the computational complexity of each feature. In particular, we filter out low information linear system parameters and then order the remaining parameters to decrease the total computation cost for classification at a prescribed accuracy. Our results indicate that the speedup factor of the time to compute the feature set using our ordering can be as high as 262. The accuracy and computation time of the feature set generated using our method is comparable to a near-optimal one, thus demonstrating the effectiveness of our technique.","Title: Hybrid Techniques for Fast Multicore Simulation\nYear: 2009\n\nAbstract: One of the challenges in the design of multicore architectures concerns the fast evaluation of hardware design-tradeoffs using simulation techniques. Simulation tools for multicore architectures tend to have long execution times that grow linearly with the number of cores simulated. In this paper, we present two hybrid techniques for fast and accurate multicore simulation. Our first method, the Monte Carlo Co-Simulation (MCCS) scheme, considers application phases, and within each phase, interleaves a Monte Carlo modeling scheme with a traditional simulator, such as Simics. Our second method, the Curve Fitting Based Simulation (CFBS) scheme, is tailored to evaluate the behavior of applications with multiple iterations, such as scientific applications that have consistent cycles per instruction (CPI) behavior within a subroutine over different iterations. In our CFBS method, we represent the CPI profile of a subroutine as a signature using curve fitting and represent the entire application execution as a set of signatures to predict performance metrics. Our results indicate that MCCS can reduce simulation time by as much as a factor of 2.37, with a speedup of 1.77 on average compared to Simics. We also observe that CFBS can reduce simulation time by as much as a factor of 13.6, with a speedup of 6.24 on average. The observed average relative errors in CPI compared to Simics are 32% for MCCS and significantly lower, at 2%, for CFBS.","Title: Link Shutdown Opportunities During Collective Communications in 3-D Torus Nets\nYear: 2007\n\nAbstract: As modern computing clusters used in scientific computing applications scale to ever-larger sizes and capabilities, their operational energy costs have be- come prohibitive. While it is an emerging trend in modern cluster design to optimize for low energy consumption in the individual computational nodes, little attention has been paid to reducing the energy used by the communication network that connects the nodes. In this work. we consider a 3-D torus network similar to the one in BlueGene/L to ex- plore opporunities for link shutdown during collec- tive communication operations. For example, we demonstrate that in the case of all-to-one reduce codes, approximately 99% of the total network link time can be spent in a shutoff state on a 64-node toroidal network, thus reducing the overall system energy by approximately 15-28%","Title: Parallel Hybrid Preconditioning: Incomplete Factorization with Selective Sparse Approximate Inversion\nYear: 2010\n\nAbstract: We consider parallel preconditioning to solve large sparse linear systems $Ax=b$ using conjugate gradients when $A$ is symmetric and positive definite. We develop a preconditioner that can be viewed as a hybrid of incomplete factorization and sparse approximate inversion schemes. Such a hybrid can potentially enable fast and reliable solution through a preconditioner with low memory requirements that allows latency-tolerant construction and application on multiprocessor systems. We propose a parallel hybrid scheme which yields a preconditioner as a tree-structured aggregate of sparse incomplete factors and inverses of selected submatrices. We analyze the computation and communication costs of our hybrid preconditioner and report on its parallel performance on some well-known test matrices. Our results indicate that our hybrid has significant advantages over sparse approximate inverse preconditioners and incomplete Cholesky preconditioners using either drop-threshold or zero-level-of-fill schemes.","Title: Time-memory trade-offs using sparse matrix methods for large-scale eigenvalue problems\nYear: 2003\n\nAbstract: Iterative methods such as Lanczos and Jacobi-Davidson are typically used to compute a small number of eigenvalues and eigenvectors of a sparse matrix. However, these methods are not effective in certain large-scale applications, for example, \"global tight binding molecular dynamics.\" Such applications require all the eigenvectors of a large sparse matrix; the eigenvectors can be computed a few at a time and discarded after a simple update step in the modeling process. We show that by using sparse matrix methods, a direct-iterative hybrid scheme can significantly reduce memory requirements while requiring less computational time than a banded direct scheme. Our method also allows a more scalable parallel formulation for eigenvector computation through spectrum slicing. We discuss our method and provide empirical results for a wide variety of sparse matrix test problems.","Title: Fault tolerant preconditioned conjugate gradient for sparse linear system solution\nYear: 2012\n\nAbstract: In scientific applications that involve dense matrices, checksum encodings have yielded \"algorithm-based fault tolerance\" (ABFT) in the event of data corruption from either hard or transient (soft) errors in the hardware. However, such checksum-based ABFT techniques have not been developed when sparse matrices are involved, for example, in sparse linear system solution through a method such as preconditioned conjugate gradients (PCG). In this paper, we develop a new sparse checksum encoded algorithm-based fault tolerant PCG, S-ABFT-PCG. Our checksum based approach can be applied to all the key operations in PCG, including sparse matrix-vector multiplication (SpMV), vector operations and the application of a preconditioner through sparse triangular solution. We prove that our approach detects a single error in the matrix and vector elements and in the metadata representing the sparse matrix row or column indices, when the linear system has a coefficient matrix that is symmetric positive definite and strictly diagonally dominant. The overhead of S-ABFT-PCG is proportional to the cost of a few O(n) vector operations, a value that is relatively low compared to the total cost of a PCG iteration with an SpMV and two triangular solutions. However, if an error is detected, then the underlying PCG iteration must be recomputed because our approach does not enable checksum encoded recovery from the error. We compare our S-ABFT-PCG with a classical ABFT-PCG (C-ABFT-PCG) that detects and recovers from a single error in the SpMV kernel, but does not provide fault tolerance for the sparse triangular solution kernel. Our experimental results indicate that in the event of no errors, compared to a PCG with no ABFT, the overheads of S-ABFT-PCG are 11.3% and lower than the 23.1% overheads of C-ABFT-PCG. Furthermore, in the event of a single error in the application of the preconditioner through triangular solution, C-ABFT-PCG suffers from significant increases in iteration counts, leading to performance degradations of 63.2% on average compared to 3.2% on average for S-ABFT-PCG.","Title: Large-Scale Normal Coordinate Analysis On Distributed Memory Parallel Systems\nYear: 2002\n\nAbstract: A parallel computational scheme for analyzing large-scale molecular vibration on distributed memory computing platforms is presented in this paper. This method combines the implicitly restarted Lanczos algorithm with a state-of-art parallel sparse direct solver to compute a set of low frequency vibrational modes for molecular systems containing tens of thousands of atoms. Although the original motivation for developing such a scheme was to overcome memory limitations on traditional sequential and shared memory machines, our computational experiments show that with a careful parallel design and data partitioning scheme one can achieve scalable performance on lightly coupled distributed memory parallel systems. In particular, we demonstrate performance enhancement achieved by using the latency tolerant \"selective inversion\" scheme in the sparse triangular substitution phase of the computation.","Title: Incomplete Cholesky Parallel Preconditioners with Selective Inversion\nYear: 1999\n\nAbstract: Consider the solution of a large linear system when the coe cient matrix is sparse, symmetric, and positive de nite. One approach is the method of \\conjugate gradient\" (CG) with an incomplete Cholesky (IC) preconditioner (ICCG). A key problem with the design of a parallel ICCG solver is the bottleneck posed by repeated parallel sparse triangular solves to apply the preconditioner. Our work concerns the use of \\selective inversion\" techniques to replace parallel substitution schemes (for triangular solution) by e cient, scalable matrix-vector multiplication. We report on the performance of our parallel solver by summarizing results of experiments on both SMPs and message-passing multiprocessors.","Title: Poster reception - Toward a power efficient computer architecture for Barnes-Hut N-body simulations\nYear: 2006\n\nAbstract: Recent improvements in processor performance have been accompanied by increased chip complexity and power consumption, resulting in increased heat dissipation. This has resulted in higher cooling costs and lower reliability. In this paper, we focus on power-aware high performance scientific computing and in particular the Barnes-Hut (BH) code that is used for N-body problems. We show how low power modes of the CPU and caches, and hardware optimizations such as a load miss predictor and data prefetchers enable BH to operate at lower power configurations with out performance degradation. On our optimized processor, power is reduced by 57% and energy is reduced by 58% with no performance penalty using simulations with SimpleScalar and Wattch. Consequently, the energy efficiency of the processor increases by a factor of more than two when compared to the base architecture.","Title: Parallel hybrid sparse solvers through flexible incomplete cholesky preconditioning\nYear: 2004\n\nAbstract: We consider parallel preconditioning schemes to accelerate the convergence of Conjugate Gradients (CG) for sparse linear system solution. We develop methods for constructing and applying preconditioners on multiprocessors using incomplete factorizations with selective inversion for improved latency-tolerance. We provide empirical results on the efficiency, scalability and quality of our preconditioners for sparse matrices from model grids and some problems from practical applications. Our results indicate that our preconditioners enable more robust sparse linear system solution.","Title: On improving performance and energy profiles of sparse scientific applications\nYear: 2006\n\nAbstract: In many scientific applications, the majority of the execution time is spent within a few basic sparse kernels such as sparse matrix vector multiplication (SMV). Such sparse kernels can utilize only a fraction of the available processing speed because of their relatively large number of data accesses per floating point operation, and limited data locality and data re-use. Algorithmic changes and tuning of codes through blocking and loop unrolling schemes can improve performance but such tuned versions are typically not available in benchmark suites such as the SPEC CFP 2000. In this paper, we consider sparse SMV kernels with different levels of tuning that are representative of this application space. We emulate certain memory subsystem optimizations using SimpleScalar and Wattch to evaluate improvements in performance and energy metrics. We also characterize how such an evaluation can be affected by the interplay between code tuning and memory subsystem optimizations. Our results indicate that the optimizations reduce execution time by over 40%, and the energy by over 85%, when used with power control modes of CPUs and caches. Furthermore, the relative impact of the same set of memory subsystem optimizations can vary significantly depending on the level of code tuning. Consequently, it may be appropriate to augment traditional benchmarks by tuned kernels typical of high performance sparse scientific codes to enable comprehensive evaluations of future systems.","Title: Characterizing the performance and energy attributes of scientific simulations\nYear: 2006\n\nAbstract: We characterize the performance and energy attributes of scientific applications based on nonlinear partial differential equations (PDEs). where the dominant cost is that of sparse linear system solution. We obtain performance and energy metrics using cycle-accurate emulations on a processor and memory system derived from the PowerPC RISC architecture with extensions to resemble the processor in the BlueGene/L. These results indicate that low-power modes of CPUs such as Dynamic Voltage Scaling (DVS) can indeed result in energy savings at the expense of performance degradation. We then consider the impact of certain memory subsystem optimizations to demonstrate that these optimizations in conjunction with DVS can provide faster execution time and lower energy consumption. For example, on the optimized architecture, if DVS is used to scale down the processor to 600MHz, execution times are faster by 45% with energy reductions of 75% compared to the original architecture at 1GHz. The insights gained from this study can help scientific applications better utilize the low-power modes of processors as well as guide the selection of hardware optimizations in future power-aware, high-performance computers.","Title: Phase-aware adaptive hardware selection for power-efficient scientific computations\nYear: 2007\n\nAbstract: Increased power consumption and heat dissipation have become the major limiters of available computational resources at many high performance computing (HPC) centers. Applications that run at such centers typically operate in single user mode, run for long periods of time, and have long lasting application phases. Their users are interested in obtaining the maximum performance. We propose a phase aware adaptive hardware selection technique, featuring data prefetchers and dynamic voltage and frequency scaling. Our technique takes advantage of memory bound phases in scientific codes, resulting in significant power (39%) and energy (37%) reductions while maintaining or exceeding the performance of an unoptimized system.","Title: Intra-application shared cache partitioning for multithreaded applications\nYear: 2010\n\nAbstract: In this paper, we address the problem of partitioning a shared cache when the executing threads belong to the same application.","Title: PFFTC: An improved fast Fourier transform for the IBM cell broadband engine\nYear: 2010\n\nAbstract: The Fast Fourier Transform (FFT) is a widely used algorithm that is frequently employed in environments where high performance is critical. In the context of embedded systems, FFTs often have hard runtime constraints and must be evaluated using limited hardware. In this paper, we present a partitioned FFT algorithm (PFFTC) for the Cell Broadband Engine ( Cell BE) that improves upon previous FFT implementations for this platform. PFFTC has three main phases to (i) partition the problem into independent sub-problems, (ii) solve the sub-problems in parallel, and (iii) combine the results of the sub-problems to obtain the solution to the original problem. PFFTC includes optimizations for exploiting data transfer parallelism, avoiding unnecessary communication through careful data routing, avoiding data dependency stalls with instruction-level double buffering, and minimizing synchronization overhead through the use of an \"asynchronous\" single-based barrier. We evaluate the performance of PFFTC and other FFT algorithms for the Cell BE. Our results indicate that PFFTC attains a peak processing rate 33.6 GFLOPS, and achieves speedups ranging form 31% to 62% over the previous Cell BE FFT algorithm's reported performance for complex single-precision FETs with 1,024-16,384 data points. (C) 2010 Published by Elsevier Ltd.","Title: Virtual I/O caching: dynamic storage cache management for concurrent workloads\nYear: 2011\n\nAbstract: A leading cause of reduced or unpredictable application performance in distributed systems is contention at the storage layer, where resources are multiplexed among many concur rent data intensive workloads. We target the shared storage cache, used to alleviate disk I/O bottlenecks, and propose a new caching paradigm to both improve performance and reduce memory requirements for HPC storage systems. We present the virtual I/O cache, a dynamic scheme to manage a limited storage cache resource. Application behavior and the corresponding performance of a chosen replacement policy are observed at run time, and a mechanism is designed to mitigate suboptimal behavior and increase cache efficiency. We further use the virtual I/O cache to isolate concurrent workloads and globally manage physical resource allocation towards system level performance objectives. We evaluate our scheme using twenty I/O intensive applications and benchmarks. Average hit rate gains over 17% were observed for isolated workloads, as well as cache size reductions near 80% for equivalent performance levels. Our largest concurrent workload achieved hit rate gains over 23%, and an over 80% iso-performance cache reduction.","Title: Can models of scientific software-hardware interactions be predictive?\nYear: 2011\n\nAbstract: Sparse scientific codes face grave performance challenges as memory bandwidth limitations grow on multi-core architectures. We investigate the memory behavior of a key sparse scientific kernel and study model-driven performance evaluation in this scope. We propose the Coupled Reuse-Cache Model (CRC Model), to enable multilevel cache performance analysis of parallel sparse codes. Our approach builds separate probabilistic application and hardware models, which are coupled to discover unprecedented insight into software-hardware interactions in the cache hierarchy. We evaluate our model's predictive performance with the pervasive sparse matrix-vector product kernel, using 1 to 16 cores and multiple cache configurations. For multi-core setups, average L1 and L2 prediction errors are within 3% and 6% respectively.","Title: Effective Preconditioning through Ordering Interleaved with Incomplete Factorization\nYear: 2006\n\nAbstract: Consider an incomplete Cholesky factorization of a sparse symmetric positive definite matrix. It is common practice to start with a symmetric permutation of the rows and columns of the matrix using an ordering to reduce fill in the complete Cholesky factor. Such an approach has two drawbacks. First, such an ordering is designed to reduce fill or operation counts in the complete Cholesky factor, and thus does not necessarily address the issue of controlling fill or operation counts during incomplete factorization. Second, because the ordering is determined in advance of the incomplete factorization, it is not easy to accommodate alternative pivoting sequences, for example, using numeric measures to promote stability, while taking into account their impact on fill and operation counts. In this paper, we consider an alternative approach that interleaves ordering with numeric computation in an incomplete Cholesky factorization. Such an interleaved scheme controls fill and operation counts. It also allows the incorporation of some limited, pivot selection strategies for stability. We demonstrate through experiments that our interleaved minimum-degree approach leads to fewer failures during incomplete factorization and improved convergence when the incomplete factor is used as a preconditioner for the conjugate gradient method. We conjecture that the improvements in the quality of preconditioning arise from the ability of our method to generate better approximations to the complete factor.","Title: A Combinatorial Scheme for Developing Efficient Composite Solvers\nYear: 2002\n\nAbstract: Many fundamental problems in scientific computing have more than one solution method. It is not uncommon for alternative solution methods to represent different tradeoffs between solution cost and reliability. Furthermore, the performance of a solution method often depends on the numerical properties of the problem instance and thus can vary dramatically across application domains. In such situations, it is natural to consider the construction of a multi-method composite solver to potentially improve both the average performance and reliability. In this paper, we provide a combinatorial framework for developing such composite solvers. We provide analytical results for obtaining an optimal composite from a set of methods with normalized measures of performance and reliability. Our empirical results demonstrate the effectiveness of such optimal composites for solving large, sparse linear systems of equations.","Title: Exploiting dense substructures for fast sparse matrix vector multiplication\nYear: 2011\n\nAbstract: The execution time of many scientific computing applications is dominated by the time spent in performing sparse matrix vector multiplication (SMV; y â聠聬 A 脗· x). We consider improving the performance of SMV on multicores by exploiting the dense substructures that are inherently present in many sparse matrices derived from partial differential equation models. First, we identify indistinguishable vertices, i.e., vertices with the same adjacency structure, in a graph representation of the sparse matrix (A) and group them into a supernode. Next, we identify effectively dense blocks within the matrix by grouping rows and columns in each supernode. Finally, by using a suitable data structure for this representation of the matrix, we reduce the number of load operations during SMV while exactly preserving the original sparsity structure of A. In addition, we use ordering techniques to enhance locality in accesses to the vector, x, to yield an SMV kernel that exploits the effectively dense substructures in the matrix. We evaluate our scheme on Intel Nehalem and AMD Shanghai processors. We observe that for larger matrices on the Intel Nehalem processor, our method improves performance on average by 37.35% compared with the traditional compressed sparse row scheme (a blocked compressed form improves performance on average by 30.27%). Benefits of our new format are similar for the AMD processor. More importantly, if we pick for each matrix the best among our method and the blocked compressed scheme, the average performance improvements increase to 40.85%. Additional results indicate that the best performing scheme varies depending on the matrix and the system. We therefore propose an effective density measure that could be used for method selection, thus adding to the variety of options for an auto-tuned optimized SMV kernel that can exploit sparse matrix properties and hardware attributes for high performance.","Title: Analysis of the IPv4 Address Space Delegation Structure\nYear: 2007\n\nAbstract: The Internet has grown tremendously in terms of the number of users who rely on it and the number of orga- nizations that are connected to it. Characterizing how this growth affects its structure and topology is vitally impor- tant to determine the fundamental characteristics and limi- tations that must be handled, such as address space exhaus- tion; understanding the process of allocating and delegat- ing address space can help to answer these questions. In this paper, we analyze BGP routing data to study the struc- ture and growth of IPv4 address space allocation, fragmen- tation and usage. We explore the notion of delegation rela- tionships among prefixes and use this information to con- struct an autonomous system (AS) delegation tree. We show that delegation in the Internet is not significantly correlated to the underlying topology or AS customer-provider rela- tionships. We also analyze the fragmentation and usage of address space over a period of five years and examine pre- fixes that are delegated by organizations vs. those that are not delegated. We notice that the address space usage due to delegating prefixes is increasing at the same rate as the ad- dress space usage due to non-delegating prefixes. This indi- cates that fragmentation rate of the address space is actu- ally almost a constant with respect to total address usage. Additionally, we show that most delegation is performed by a small number of organizations, which may aid in the im- plementation of a public-key infrastructure for the Internet.","Title: Adapting Sparse Triangular Solution to GPUs\nYear: 2012\n\nAbstract: High performance computing systems are increasingly incorporating hybrid CPU/GPU nodes to accelerate the rate at which floating point calculations can be performed for scientific applications. Currently, a key challenge is adapting scientific applications to such systems when the underlying computations are sparse, such as sparse linear solvers for the simulation of partial differential equation models using semi-implicit methods. Now, a key bottleneck is sparse triangular solution for solvers such as preconditioned conjugate gradients (PCG). We show that sparse triangular solution can be effectively mapped to GPUs by extracting very large degrees of fine-grained parallelism using graph coloring. We develop simple performance models to predict these effects at intersection of the data and hardware attributes and we evaluate our scheme on a Nvidia Tesla M2090 GPU relative to the level set scheme developed at NVIDIA. Our results indicate that our approach significantly enhances the available fine-grained parallelism to speed-up PCG iteration time compared to the NVIDIA scheme, by a factor with a geometric mean of 5.41 on a single GPU, with speedups as high as 63 in some cases.","Title: T-NUCA - a novel approach to non-uniform access latency cache architectures for 3D CMPs\nYear: 2010\n\nAbstract: We consider a non-uniform access latency cache architecture (NUCA) design for 3D chip multi-processors (CMPs) where cache structures are divided into small banks interconnected by a network-on-chip (NoC). In earlier NUCA designs, data is placed in banks either statically (S-NUCA) or dynamically (D-NUCA). In both S-NUCA and D-NUCA designs, scaling to hundreds of cores can pose several challenges. Thus, we propose a new NUCA architecture with an inclusive, octal tree-based, hierarchical directory (T-NUCA-8), with the potential to scale to hundreds of cores with performance comparable to D-NUCA at a fraction of the energy cost. Our evaluations indicate that relative to D-NUCA, our T-NUCA-8 reduces network usage by 92%, energy by 87%, and EDP by 87%, at performance cost of 10%.","Title: Analyzing the soft error resilience of linear solvers on multicore multiprocessors\nYear: 2010\n\nAbstract: As chip transistor densities continue to increase, soft errors (bit flips) are becoming a significant concern in networked multiprocessors with multicore nodes. Large cache structures in multicore processors are especially susceptible to soft errors as they occupy a significant portion of the chip area. In this paper, we consider the impacts of soft errors in caches on the resilience and energy efficiency of sparse linear solvers. In particular, we focus on two widely used sparse iterative solvers, namely Conjugate Gradient (CG) and Generalized Minimum Residuals (GMRES). We propose two adaptive schemes, (i) a Write Eviction Hybrid ECC (WEH-ECC) scheme for the L1 cache and (ii) a Prefetcher Based Adaptive ECC (PBA-ECC) scheme for the L2 cache, and evaluate the energy and reliability trade-offs they bring in the context of GMRES and CG solvers. Our evaluations indicate that WEH-ECC reduces the CG and GMRES soft error vulnerability by a factor of 18 to 220 in L1 cache, relative to an unprotected L1 cache, and energy consumption by 16%, relative to a cache with strong protection. The PBA-ECC scheme reduces the CG and GMRES soft error vulnerability by a factor of 9 Ã 103 to 8.6 Ã 109, relative to an unprotected L2 cache, and reduces the energy consumption by 8.5%, relative to a cache with strong ECC protection. Our energy overheads over unprotected L1 and L2 caches are 5% and 14% respectively.","Title: Intra-application cache partitioning\nYear: 2010\n\nAbstract: Efficient management of shared on-chip resources such as the shared level 2 (L2) cache has become an important problem with the emergence of chip multiprocessors (CMPs). Partitioning the shared cache in chip multiprocessors (CMPs) among concurrently executing applications can provide important benefits such as throughput improvement, fairness guarantees, and quality of service (QoS) enhancements. In this paper, we pose an interesting related question, which is, if partitioning the shared cache space among concurrently executing threads of the same application can enhance the application performance. We address this problem by identifying and speeding up the slowest thread, also termed as the critical path thread, during each execution interval since the overall performance of a multithreaded application is determined by the critical path thread. To do so, we propose a dynamic, runtime system based, cache partitioning scheme that partitions the shared cache space dynamically among the individual threads of a given application. In a nutshell, we wish to take some cache space away from the faster threads and give it to the critical path thread at each execution interval. We show that speeding up the critical path thread this way, results in overall performance enhancement of the application execution in the long term. Our experimental evaluation indicates that, the proposed dynamic cache partitioning scheme yields benefits up to 15% over a shared cache with no partitions, up to 23% over a statically partitioned cache (private cache) and up to 20% over a throughput-oriented scheme.","Title: NUMA-aware graph mining techniques for performance and energy efficiency\nYear: 2012\n\nAbstract: We investigate dynamic methods to improve the power and performance profiles of large irregular applications on modern multi-core systems. In this context, we study a large sparse graph application, Betweenness Centrality, and focus on memory behavior as core count scales. We introduce new techniques to efficiently map the computational demands onto non-uniform memory architectures (NUMA). Our dynamic design adapts to hardware topology and dramatically improves both energy and performance. These gains are more significant at higher core counts. We implement a scheme for adaptive data layout, which reorganizes the graph after observing parallel access patterns, and a dynamic task scheduler that encourages shared data between neighboring cores. We measure performance and energy consumption on a modern multi-core machine and observe that mean execution time is reduced by 51.2% and energy is reduced by 52.4%.","Title: STS-k: a multilevel sparse triangular solution scheme for NUMA multicores\nYear: 2015\n\nAbstract: We consider techniques to improve the performance of parallel sparse triangular solution on non-uniform memory architecture multicores by extending earlier coloring and level set schemes for single-core multiprocessors. We develop STS-k, where k represents a small number of transformations for latency reduction from increased spatial and temporal locality of data accesses. We propose a graph model of data reuse to inform the development of STS-k and to prove that computing an optimal cost schedule is NP-complete. We observe significant speed-ups with STS-3 on 32-core Intel Westmere-Ex and 24-core AMD `MagnyCours' processors. Incremental gains solely from the 3-level transformations in STS-3 for a fixed ordering, correspond to reductions in execution times by factors of 1.4(Intel) and 1.5(AMD) for level sets and 2(Intel) and 2.2(AMD) for coloring. On average, execution times are reduced by a factor of 6(Intel) and 4(AMD) for STS-3 with coloring compared to a reference implementation using level sets.","Title: Phase Detection with Hidden Markov Models for DVFS on Many-Core Processors\nYear: 2015\n\nAbstract: The energy concerns of many-core processors are increasing with the number of cores. We provide a new method that reduces energy consumption of an application on many-core processors by identifying unique segments to apply dynamic voltage and frequency scaling (DVFS). Our method, phase-based voltage and frequency scaling (PVFS), hinges on the identification of phases, i.e., Segments of code with unique performance and power attributes, using hidden Markov Models. In particular, we demonstrate the use of this method to target hardware components on many-core processors such as Network-on-Chip (NoC). PVFS uses these phases to construct a static power schedule that uses DVFS to reduce energy with minimal performance penalty. This general scheme can be used with a variety of performance and power metrics to match the needs of the system and application. More importantly, the flexibility in the general scheme allows for targeting of the unique hardware components of future many-core processors. We provide an in-depth analysis of PVFS applied to five threaded benchmark applications, and demonstrate the advantage of using PVFS for 4 to 32 cores in a single socket. Empirical results of PVFS show a reduction of up to 10.1% of total energy while only impacting total time by at most 2.7% across all core counts. Furthermore, PVFS outperforms standard coarse-grain time-driven DVFS, while scaling better in terms of energy savings with increasing core counts.","Title: A multilevel compressed sparse row format for efficient sparse computations on multicore processors\nYear: 2014\n\nAbstract: We seek to improve the performance of sparse matrix computations on multicore processors with non-uniform memory access (NUMA). Typical implementations use a bandwidth reducing ordering of the matrix to increase locality of accesses with a compressed storage format to store and operate only on the non-zero values. We propose a new multilevel storage format and a companion ordering scheme as an explicit adaptation to map to NUMA hierarchies. More specifically, we propose CSR-k, a multilevel form of the popular compressed sparse row (CSR) format for a multicore processor with k > 1 well-differentiated levels in the memory subsystem. Additionally, we develop Band-k, a modified form of a traditional bandwidth reduction scheme, to convert a matrix represented in CSRto our proposed CSR-k. We evaluate the performance of the widely-used and important sparse matrix-vector multiplication (SpMV) kernel using CSR-2 on Intel Westmere processors for a test suite of 12 large sparse matrices with row densities in the range 3 to 45. On 32 cores, on average across all matrices in the test suite, the execution time for SpMV with CSR-2is less than 42% of the time taken by the state-of-the-art automatically tuned SpMV resulting in energy savings of approximately 56%. Additionally, on average, the parallel speed-up on 32 cores of the automatically tuned SpMV relative to its 1-core performance is 8.18 compared to a value of 19.71 for CSR-2. Our analysis indicates that the higher performance of SpMV with CSR-2 comes from achieving higher reuse of x in the shared L3 cache without incurring overheads from fill-in of original zeroes. Furthermore, the pre-processing costs of SpMV with CSR-2 can be amortized on average over 97 iterations of SpMV using CSR and are substantially lower than the 513 iterations required for the automatically tuned implementation. Based on these results, CSR-k appears to be a promising multilevel formulation of CSR for adapting sparse computations to multico- e processors with NUMA memory hierarchies.","Title: Locality-Aware Laplacian Mesh Smoothing\nYear: 2016\n\nAbstract: In this paper, we propose a novel reordering scheme to improve the performance of a Laplacian Mesh Smoothing (LMS). While the Laplacian smoothing algorithm is well optimized and studied, we show how a simple reordering of the vertices of the mesh can greatly improve the execution time of the smoothing algorithm. The idea of our reordering is based on (i) the postulate that cache misses are a very time consuming part of the execution of LMS, and (ii) the study of the reuse distance patterns of various executions of the LMS algorithm. Our reordering algorithm is very simple but allows for huge performance improvement. We ran it on a Westmere-EX platform and obtained a speedup of 75 on 32 cores compared to the single core execution without reordering, and a gain in execution of 32% on 32 cores compared to state of the art reordering. Finally, we show that we leave little room for a better ordering by reducing the L2 and L3 cache misses to a bare minimum.","Title: Research and Education in Computational Science and Engineering.\nYear: 2018\n\nAbstract: This report presents challenges, opportunities, and directions for computational science and engineering (CSE) research and education for the next decade. Over the past two decades the field of CSE has penetrated both basic and applied research in academia, industry, and laboratories to advance discovery, optimize systems, support decision-makers, and educate the scientific and engineering workforce. Informed by centuries of theory and experiment, CSE performs computational experiments to answer questions that neither theory nor experiment, alone is equipped to answer. CSE provides scientists and engineers with algorithmic inventions and software systems that, transcend disciplines and scales. CSE brings the power of parallelism to bear on troves of data. Mathematics-based advanced computing has become a prevalent means of discovery and innovation in essentially all areas of science, engineering, technology, and society, and the CSE community is at the core of this transformation. However, a combination of disruptive developments-including the architectural complexity of extreme-scale computing, the data revolution and increased attention to data-driven discovery, and the specialization required to follow the applications to new frontiers-is redefining the scope and reach of the CSE endeavor. With these many current and expanding opportunities for the CSE field, there is a growing demand for CSE graduates and a need to expand CSE educational offerings. This need includes CSE programs at both the undergraduate and graduate levels, as well as continuing education and professional development programs, exploiting the synergy between computational science and data science. Yet, as institutions consider new and evolving educational programs, it is essential to consider the broader research challenges and opportunities that provide the context for CSE education and workforce development.","Title: Identifying the Right Replication Level to Detect and Correct Silent Errors at Scale\nYear: 2017\n\nAbstract: This paper provides a model and an analytical study of replication as a technique to detect and correct silent errors. Although other detection techniques exist for HPC applications, based on algorithms (ABFT), invariant preservation or data analytics, replication remains the most transparent and least intrusive technique. We explore the right level (duplication, triplication or more) of replication needed to efficiently detect and correct silent errors. Replication is combined with checkpointing and comes with two flavors: process replication and group replication. Process replication applies to message-passing applications with communicating processes. Each process is replicated, and the platform is composed of process pairs, or triplets. Group replication applies to black-box applications, whose parallel execution is replicated several times. The platform is partitioned into two halves (or three thirds). In both scenarios, results are compared before each checkpoint, which is taken only when both results (duplication) or two out of three results (triplication) coincide. If not, one or more silent errors have been detected, and the application rolls back to the last checkpoint. We provide a detailed analytical study of both scenarios, with formulas to decide, for each scenario, the optimal parameters as a function of the error rate, checkpoint cost, and platform size. We also report a set of extensive simulation results that corroborates the analytical model.","Title: Co-scheduling Amdahl applications on cache-partitioned systems\nYear: 2018\n\nAbstract: AbstractCache-partitioned architectures allow subsections of the shared last-level cache LLC to be exclusively reserved for some applications. This technique dramatically limits interactions between applications that are concurrently executing on a multicore machine. Consider n applications that execute concurrently, with the objective to minimize the makespan, defined as the maximum completion time of the n applications. Key scheduling questions are as follows: i which proportion of cache and ii how many processors should be given to each application? In this article, we provide answers to i and ii for Amdahl applications. Even though the problem is shown to be NP-complete, we give key elements to determine the subset of applications that should share the LLC while remaining ones only use their smaller private cache. Building upon these results, we design efficient heuristics for Amdahl applications. Extensive simulations demonstrate the usefulness of co-scheduling when our efficient cache partitioning strategies are deployed.","Title: Realizing the potential of data science.\nYear: 2018\n\nAbstract: Data science promises new insights, helping transform information into knowledge that can drive science and industry.","Title: Scheduling Parallel Tasks under Multiple Resources: List Scheduling vs. Pack Scheduling\nYear: 2018\n\nAbstract: Scheduling in High-Performance Computing (HPC) has been traditionally centered around computing resources (e.g., processors/cores). The ever-growing amount of data produced by modern scientific applications start to drive novel architectures and new computing frameworks to support more efficient data processing, transfer and storage for future HPC systems. This trend towards data-driven computing demands the scheduling solutions to also consider other resources (e.g., I/O, memory, cache) that can be shared amongst competing applications. In this paper, we study the problem of scheduling HPC applications while exploring the availability of multiple types of resources that could impact their performance. The goal is to minimize the overall execution time, or makespan, for a set of moldable tasks under multiple-resource constraints. Two scheduling paradigms, namely, list scheduling and pack scheduling, are compared through both theoretical analyses and experimental evaluations. Theoretically, we prove, for several algorithms falling in the two scheduling paradigms, tight approximation ratios that increase linearly with the number of resource types. As the complexity of direct solutions grows exponentially with the number of resource types, we also design a strategy to indirectly solve the problem via a transformation to a single-resource-type problem, which can significantly reduce the algorithms' running times without compromising their approximation ratios. Experiments conducted on Intel Knights Landing with two resource types (processor cores and high-bandwidth memory) and simulations designed on more resource types confirm the benefit of the transformation strategy and show that pack-based scheduling, despite having a worse theoretical bound, offers a practically promising and easy-to-implement solution, especially when more resource types need to be managed.","Title: Coping with silent and fail-stop errors at scale by combining replication and checkpointing.\nYear: 2018\n\nAbstract: This paper provides a model and an analytical study of replication as a technique to cope with silent errors, as well as a mixture of both silent and fail-stop errors on large-scale platforms. Compared with fail-stop errors that are immediately detected when they occur, silent errors require a detection mechanism. To detect silent errors, many application-specific techniques are available, either based on algorithms (e.g., ABFT), invariant preservation or data analytics, but replication remains the most transparent and least intrusive technique. We explore the right level (duplication, triplication or more) of replication for two frameworks: (i) when the platform is subject to only silent errors, and (ii) when the platform is subject to both silent and fail-stop errors. A higher level of replication is more expensive in terms of resource usage but enables to tolerate more errors and to even correct some errors, hence there is a trade-off to be found. Replication is combined with checkpointing and comes with two flavors: process replication and group replication. Process replication applies to message-passing applications with communicating processes. Each process is replicated, and the platform is composed of process pairs, or triplets. Group replication applies to black-box applications, whose parallel execution is replicated several times. The platform is partitioned into two halves (or three thirds). In both scenarios, results are compared before each checkpoint, which is taken only when both results (duplication) or two out of three results (triplication) coincide. Otherwise, one or more silent errors have been detected, and the application rolls back to the last checkpoint, as well as when fail-stop errors have struck. We provide a detailed analytical study for all of these scenarios, with formulas to decide, for each scenario, the optimal parameters as a function of the error rate, checkpoint cost, and platform size. We also report a set of extensive simulation results that nicely corroborates the analytical model.","Title: A Scalability and Sensitivity Study of Parallel Geometric Algorithms for Graph Partitioning\nYear: 2018\n\nAbstract: Graph partitioning arises in many computational simulation workloads, including those that involve finite difference or finite element methods, where partitioning enables efficient parallel processing of the entire simulation. We focus on parallel geometric algorithms for partitioning large graphs whose vertices are associated with coordinates in two or three-dimensional space on multi-core processors. Compared with other types of partitioning algorithms, geometric schemes generally show better scalability on a large number of processors or cores. This paper studies the scalability and sensitivity of two parallel algorithms, namely, recursive coordinate bisection (denoted by pRCB) and geometric mesh partitioning (denoted by pGMP), in terms of their robustness to several key factors that affect the partition quality, including coordinate perturbation, approximate embedding, mesh quality and graph planarity. Our results indicate that the quality of a partition as measured by the size of the edge separator (or cutsize) remains consistently better for pGMP compared to pRCB. On average for our test suite, relative to pRCB, pGMP yields 25% smaller cutsizes on the original embedding, and across all perturbations cutsizes that are smaller by at least 8% and by as much as 50%. Not surprisingly, higher quality cuts are obtained at the expense of longer execution times; on a single core, pGMP has an average execution time that is almost 10 times slower than that of pRCB, but it scales better and catches up at 32-cores to be slower by less than 20%. With the current trends in core counts that continue to increase per chip, these results suggest that pGMP presents an attractive solution if a modest number of cores can be deployed to reduce execution times while providing high quality partitions.","Title: Reservation Strategies for Stochastic Jobs\nYear: 2019\n\nAbstract: In this paper, we are interested in scheduling stochastic jobs on a reservation-based platform. Specifically, we consider jobs whose execution time follows a known probability distribution. The platform is reservation-based, meaning that the user has to request fixed-length time slots. The cost then depends on both (i) the request duration (pay for what you ask); and (ii) the actual execution time of the job (pay for what you use). A reservation strategy determines a sequence of increasing length reservations, which are paid for until one of them allows the job to successfully complete. The goal is to minimize the total expected cost of the strategy. We provide some properties of the optimal solution, which we characterize up to the length of the first reservation. We then design several heuristics based on various approaches, including a brute-force search of the first reservation length while relying on the characterization of the optimal strategy, as well as the discretization of the target continuous probability distribution together with an optimal dynamic programming algorithm for the discrete distribution. We evaluate these heuristics using two different platform models and cost functions: The first one targets a cloud oriented platform (e.g., Amazon AWS) using jobs that follow a large number of usual probability distributions (e.g., Uniform, Exponential, LogNormal, Weibull, Beta), and the second one is based on interpolating traces from a real neuroscience application executed on an HPC platform. An extensive set of simulation results show the effectiveness of the proposed reservation-based approaches for scheduling stochastic jobs.","Title: On-the-fly scheduling versus reservation-based scheduling for unpredictable workflows\nYear: 2019\n\nAbstract: AbstractScientific insights in the coming decade will clearly depend on the effective processing of large data sets generated by dynamic heterogeneous applications typical of workflows in large data centers or of emerging fields like neuroscience. In this article, we show how these big data workflows have a unique set of characteristics that pose challenges for leveraging HPC methodologies, particularly in scheduling. Our findings indicate that execution times for these workflows are highly unpredictable and are not correlated with the size of the data set involved or the precise functions used in the analysis. We characterize this inherent variability and sketch the need for new scheduling approaches by quantifying significant gaps in achievable performance. Through simulations, we show how on-the-fly scheduling approaches can deliver benefits in both system-level and user-level performance measures. On average, we find improvements of up to 35% in system utilization and up to 45% in average stretch of the applications, illustrating the potential of increasing performance through new scheduling approaches.","Title: Speculative Scheduling for Stochastic HPC Applications\nYear: 2019\n\nAbstract: New emerging fields are developing a growing number of large-scale applications with heterogeneous, dynamic and data-intensive requirements that put a high emphasis on productivity and thus are not tuned to run efficiently on today's high performance computing (HPC) systems. Some of these applications, such as neuroscience workloads and those that use adaptive numerical algorithms, develop modeling and simulation workflows with stochastic execution times and unpredictable resource requirements. When they are deployed on current HPC systems using existing resource management solutions, it can result in loss of efficiency for the users and decrease in effective system utilization for the platform providers.\n\nIn this paper, we consider the current HPC scheduling model and describe the challenge it poses for stochastic applications due to the strict requirement in its job deployment policies. To address the challenge, we present speculative scheduling techniques that adapt the resource requirements of a stochastic application on-the-fly, based on its past execution behavior instead of relying on estimates given by the user. We focus on improving the overall system utilization and application response time without disrupting the current HPC scheduling model or the application development process. Our solution can operate alongside existing HPC batch schedulers without interfering with their usage modes. We show that speculative scheduling can improve the system utilization and average application response time by 25-30% compared to the classical HPC approach.","Title: Multi-Resource List Scheduling of Moldable Parallel Jobs under Precedence Constraints.\nYear: 2021\n\nAbstract: The scheduling literature has traditionally focused on a single type of resource (e.g., computing nodes). However, scientific applications in modern High-Performance Computing (HPC) systems process large amounts of data, hence have diverse requirements on different types of resources (e.g., cores, cache, memory, I/O). All of these resources could potentially be exploited by the runtime scheduler to improve the application performance. In this paper, we study multi-resource scheduling to minimize the makespan of computational workflows comprised of parallel jobs subject to precedence constraints. The jobs are assumed to be moldable, allowing the scheduler to flexibly select a variable set of resources before execution. We propose a multi-resource, list-based scheduling algorithm, and prove that, on a system with $d$ types of schedulable resources, our algorithm achieves an approximation ratio of $1.619d+2.545\\sqrt{d}+1$ for any $d$, and a ratio of $d+O(\\sqrt[3]{d^2})$ for large $d$. We also present improved results for independent jobs and for jobs with special precedence constraints (e.g., series-parallel graphs and trees). Finally, we prove a lower bound of $d$ on the approximation ratio of any list scheduling scheme with local priority considerations. To the best of our knowledge, these are the first approximation results for moldable workflows with multiple resource requirements.","Title: Resilient Scheduling of Moldable Parallel Jobs to Cope With Silent Errors\nYear: 2022\n\nAbstract: We study the resilient scheduling of moldable parallel jobs on high-performance computing (HPC) platforms. Moldable jobs allow for choosing a processor allocation before execution, and their execution time obeys various speedup models. The objective is to minimize the overall completion time or the makespan, when jobs can fail due to silent errors and hence may need to be re-executed after each failure until successful completion. Our work generalizes the classical scheduling framework for failure-free jobs. To cope with silent errors, we introduce two resilient scheduling algorithms, \n<sc xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">Lpa-List</small>\n and \n<sc xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">Batch-List</small>\n, both of which use the \n<sc xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">List</small>\n strategy to schedule the jobs. Without knowing a priori how many times each job will fail, \n<sc xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">Lpa-List</small>\n relies on a local strategy to allocate processors to the jobs, while \n<sc xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">Batch-List</small>\n schedules the jobs in batches and allows only a restricted number of failures per job in each batch. We prove approximation ratios for the two algorithms under several prominent speedup models (e.g., roofline, communication, Amdahl, power, monotonic, and a mix model). An extensive set of simulations is conducted to evaluate different variants of the two algorithms, and the results show that they consistently outperform some baseline heuristics. Overall, our best algorithm is within a factor of 1.6 of a lower bound on average over the entire set of experiments, and within a factor of 4.2 in the worst case."],"string":"[\n \"Title: A new data-mapping scheme for latency-tolerant distributed sparse triangular solution\\nYear: 2002\\n\\nAbstract: This paper concerns latency-tolerant schemes for the efficient parallel solution of sparse triangular linear systems on distributed memory multiprocessors. Such triangular solution is required when sparse Cholesky factors are used to solve for a sequence of right-hand-side vectors or when incomplete sparse Cholesky factors are used to precondition a Conjugate Gradients iterative solver. In such applications, the use of traditional distributed substitution schemes can create a performance bottleneck when the latency of interprocessor communication is large. We had earlier developed the Selective Inversion (SI) scheme to reduce communication latency costs by replacing distributed substitution by parallel matrix vector multiplication. We now present a new two-way mapping of the triangular sparse matrix to processors to improve the performance of SI by halving its communication latency costs. We provide analytic results for model sparse matrices and we report on the performance of our scheme for parallel preconditioning with incomplete sparse Cholesky factors.\",\n \"Title: Load Miss Prediction - Exploiting Power Performance Trade-offs\\nYear: 2007\\n\\nAbstract: Modern CPUs operate at GHz frequencies, but the latencies of memory accesses are still relatively large, in the order of hundreds of cycles. Deeper cache hierarchies with larger cache sizes can mask these latencies for codes with good data locality and reuse, such as structured dense matrix computations. However, cache hierarchies do not necessarily benefit sparse scientific computing codes, which tend to have limited data locality and reuse. We therefore propose a new memory architecture with a Load Miss Predictor (LMP), which includes a data bypass cache and a predictor table, to reduce access latencies by determining whether a load should bypass the main cache hierarchy and issue an early load to main memory. Our architecture uses the L2 (and lower caches) as a victim cache for data removed from our bypass cache. We use cycle- accurate simulations, with SimpleScalar and Wattch to show that our LMP improves the performance of sparse codes, our application domain of interest, on average by 14%, with a 13.6% increase in power. When the LMP is used with dynamic voltage and frequency scaling (DVFS), performance can be improved by 8.7% with system power savings of 7.3% and energy reduction of 17.3% at 1800MHz relative to the base system at 2000MHz. Alternatively our LMP can be used to improve the performance of SPEC benchmarks by an average of 2.9% at the cost of 7.1% increase in average power.\",\n \"Title: Performance of a Fully Parallel Sparse Solver.\\nYear: 1997\\n\\nAbstract: The performance of a fully parallel direct solver for large sparse-symmetric positive definite systems of linear equations is demonstrated. The solver is designed for distributed-memory, message-passing parallel computer systems. All phases of the computation, including sym bolic processing as well as numeric factorization and triangular solution, are performed in parallel. A parallel Cartesian-nested dissection algorithm is used to compute a fill- reducing ordering for the matrix and an appropriate partitioning of the problem across the processors. The separator tree resulting from nested dissection is used to identify and exploit large-grain parallelism in the remaining steps of the computation. The parallel performance of the solver is reported for a series of test problems on the Thinking Machines CM-5 and the Intel Touchstone Delta. The parallel efficiency, scalability, and absolute perfor mance of the solver, as well as the relative importance of the various phases of the computation, are investigated empirically\",\n \"Title: Feature subspace transformations for enhancing k-means clustering\\nYear: 2010\\n\\nAbstract: Unsupervised classification typically concerns identifying clusters of similar entities in an unlabeled dataset. Popular methods include clustering based on (i) distance-based metrics between the entities in the feature space (K-Means), and (ii) combinatorial properties in a weighted graph representation of the dataset (Multilevel K-Means). In this paper, we present a force-directed graph layout based feature subspace transformation (FST) scheme to transform the dataset before the application of K-Means. Our FST-K-Means method utilizes both distance-based and combinatorial attributes of the original dataset to seek improvements in the internal and external quality metrics of unsupervised classification. We demonstrate the effectiveness of FST-K-Means in improving classification quality relative to K-Means and Multilevel K-Means (GraClus). The quality of classification is measured by observing internal and external quality metrics on a test suite of datasets. Our results indicate that on average, the internal quality metric (cluster cohesiveness) is 20.2% better than K-Means, and 6.6% better than GraClus. More significantly, FST-K-Means improves the external quality metric (accuracy) of classification on average by 14.9% relative to K-Means and 23.6% relative to GraClus.\",\n \"Title: Multi-pass mapping schemes for parallel sparse matrix computations\\nYear: 2005\\n\\nAbstract: Consider the solution of a large sparse linear system Ax = b on multiprocessors. A parallel sparse matrix factorization is required in a direct solver. Alternatively, if Krylov subspace iterative methods are used, then incomplete forms of parallel sparse factorization are required for preconditioning. In such schemes, the underlying parallel computation is tree-structured, utilizing task-parallelism at lower levels of the tree and data-parallelism at higher levels. The proportional heuristic has typically been used to map the data and computation to processors. However, for sparse systems from finite-element methods on complex domains, the resulting assignments can exhibit significant load-imbalances. In this paper, we develop a multi-pass mapping scheme to reduce such load imbalances and we demonstrate its effectiveness for a test suite of large sparse matrices. Our scheme can also be used to generate improved mappings for tree-structured applications beyond those considered in this paper.\",\n \"Title: Adapting application execution in CMPs using helper threads\\nYear: 2009\\n\\nAbstract: In parallel to the changes in both the architecture domain-the move toward chip multiprocessors (CMPs)-and the application domain-the move toward increasingly data-intensive workloads-issues such as performance, energy efficiency and CPU availability are becoming increasingly critical. The CPU availability can change dynamically due to several reasons such as thermal overload, increase in transient errors, or operating system scheduling. An important question in this context is how to adapt, in a CMP, the execution of a given application to CPU availability change at runtime. Our paper studies this problem, targeting the energy-delay product (EDP) as the main metric to optimize. We first discuss that, in adapting the application execution to the varying CPU availability, one needs to consider the number of CPUs to use, the number of application threads to accommodate and the voltage/frequency levels to employ (if the CMP has this capability). We then propose to use helper threads to adapt the application execution to CPU availability change in general with the goal of minimizing the EDP. The helper thread runs parallel to the application execution threads and tries to determine the ideal number of CPUs, threads and voltage/frequency levels to employ at any given point in execution. We illustrate this idea using four applications (Fast Fourier Transform, MultiGrid, LU decomposition and Conjugate Gradient) under different execution scenarios. The results collected through our experiments are very promising and indicate that significant EDP reductions are possible using helper threads. For example, we achieved up to 66.3%, 83.3%, 91.2%, and 94.2% savings in EDP when adjusting all the parameters properly in applications FFT, MG, LU, and CG, respectively. We also discuss how our approach can be extended to address multi-programmed workloads.\",\n \"Title: A latency tolerant hybrid sparse solver using incomplete Cholesky factorization\\nYear: 2003\\n\\nAbstract: Consider the solution of large sparse symmetric positive definite linear systems using the preconditioned conjugate gradient method. On sequential architectures, incomplete Cholesky factorizations provide effective preconditioning for systems from a variety of application domains, some of which may have widely differing preconditioning requirements. However, incomplete factorization based preconditioners are not considered suitable for multiprocessors. This is primarily because the triangular solution step required to apply the preconditioner (at each iteration) does not scale well due to the large latency of inter-processor communication. We propose a new approach to overcome this performance bottleneck by coupling incomplete factorization with a selective inversion scheme to replace triangular solutions by scalable matrix-vector multiplications. We discuss our algorithm, analyze its communication latency for model sparse linear systems, and provide empirical results on its performance and scalability. Copyright (C) 2003 John Wiley, Sons, Ltd.\",\n \"Title: A Cartesian Parallel Nested Dissection Algorithm\\nYear: 1995\\n\\nAbstract: This paper is concerned with the distributed parallel computation of an ordering for a symmetric positive definite sparse matrix. The purpose of the ordering is to limit fill and enhance concurrency in the subsequent Cholesky factorization of the matrix. A geometric approach to nested dissection is used based on a given Cartesian embedding of the graph of the matrix in Euclidean space. The resulting algorithm can be implemented efficiently on massively parallel, distributed memory computers. One unusual feature of the distributed algorithm is that its effectiveness does not depend on data locality, which is critical in this context, since an appropriate partitioning of the problem is not known until after the ordering has been determined. The ordering algorithm is the first component in a suite of scalable parallel algorithms currently under development for solving large sparse linear systems on massively parallel computers.\",\n \"Title: Poster reception - Energy/performance modeling for collective communication in 3-D torus cluster networks\\nYear: 2006\\n\\nAbstract: As supercomputers scale ever larger, energy consumption in interconnection networks is an emerging problem. In this work, we analyze the energy consumption and traffic patterns in a 3-D torus network in order to locate and exploit opportunities to save energy by disabling network links dynamically. Using a custom-built simulator, TorusSim, we show that, for common scientific computing codes that utilize collective communications, regularities in the network and algorithmic data flow result in many unused and under-utilized links that can be disabled to save energy at no performance cost. In the case of a reduce operation, we see that at least 56% of the links in a 4x4x4 torus network can be disabled during communication, with significant other opportunity to save energy on under-utilized links that could lead to over 80% overall link energy savings.\",\n \"Title: Towards energy efficient scaling of scientific codes\\nYear: 2008\\n\\nAbstract: Energy consumption is becoming a crucial concern within the high performance computing community as computers expand to the peta-scale and beyond. Although the peak execution rates on tuned dense matrix operations in supercomputers have consistently increased to approach the peta-scale regime, the linear scaling of peak execution rates has been achieved at the expense of cubic growth in power with systems already appearing in the megawatt range. In this paper, we extend the ideas of algorithm scalability and performance iso-efficiency to characterize the system-wide energy consumption. The latter includes dynamic and leakage energy for CPUs, memories and network interconnects. We propose analytical models for evaluating energy scalability and energy efficiency. These models are important for understanding the power consumption trends of data intensive applications executing on a large number of processors. We apply the models to two scientific applications to explore opportunities when using voltage/frequency scaling for energy savings without degrading performance. Our results indicate that such models are critical for energy-aware high-performance computing in the tera- to peta-scale regime.\",\n \"Title: Advanced algorithms and software components for scientific computing: an introduction\\nYear: 2004\\n\\nAbstract: Scientific computing concerns the design, analysis and implementation of algorithms and software to enable computational modeling and simulation across disciplines. Recent research in scientific computing has been spurred both by advances in multiprocessor systems and the wider acceptance of computational modeling as a third mode of scientific investigation, in addition in to theory and experiment. We introduce the next six chapters on advanced algorithms and software components for scientific computing on parallel computers. We review recent results toward enabling the scalable solution of large-scale modeling applications.\",\n \"Title: Conjugate gradient sparse solvers: performance-power characteristics\\nYear: 2006\\n\\nAbstract: We characterize the performance and power attributes of the conjugate gradient (CG) sparse solver which is widely used in scientific applications. We use cycle-accurate simulations with SimpleScalar and Wattch, on a processor and memory architecture similar to the configuration of a node of the BlueGene/L. We first demonstrate that substantial power savings can be obtained without performance degradation if low power modes of caches can be utilized. We next show that if Dynamic Voltage Scaling (DVS) can be used, power and energy savings are possible, but these are realized only at the expense of performance penalties. We then consider two simple memory subsystem optimizations, namely memory and level-2 cache prefetching. We demonstrate that when DVS and low power modes of caches are used with these optimizations, performance can be improved significantly with reductions in power and energy. For example, execution time is reduced by 23%, power by 55% and energy by 65% in the final configuration at 500 MHz relative to the original at 1 GHz. We also use our codes and the CG NAS benchmark code to demonstrate that performance and power profiles can vary significantly depending on matrix properties and the level of code tuning. These results indicate that architectural evaluations can benefit if traditional benchmarks are augmented with codes more representative of tuned scientific applications.\",\n \"Title: A Grid Computing Environment for Enabling Large Scale Quantum Mechanical Simulations\\nYear: 2000\\n\\nAbstract: This paper describes work-in-progress towards developing a simulation environment that utilizes recent advances in in the areas of grid middleware and computational kernels. Our goal is to develop an environment suitable for composing and deploying an overall high-performance, flexible and robust software solution for large-scale quantum mechanical simulations.\",\n \"Title: Integrated link/CPU voltage scaling for reducing energy consumption of parallel sparse matrix applications\\nYear: 2006\\n\\nAbstract: Reducing power consumption is quickly becoming a first-class optimization metric for many high-performance parallel computing platforms. One of the techniques employed by many prior proposals along this direction is voltage scaling and past research used it on different components such as networks, CPUs, and memories. In contrast to most of the existent efforts on voltage scaling that target a single component (CPU, network or memory components), this paper proposes and experimentally evaluates a voltage/frequency scaling algorithm that considers CPU and communication links in a mesh network at the same time. More specifically, it scales voltages/frequencies of both CPUs in the network and the communication links among them in a coordinated fashion (instead of one after another) such that energy savings are maximized without impacting execution time. Our experiments with several tree-based sparse matrix computations reveal that the proposed integrated voltage scaling approach is very effective in practice and brings 13% and 17% energy savings over the pure CPU and pure communication link voltage scaling schemes, respectively. The results also show that our savings are consistent with the different network sizes and different sets of voltage/frequency levels\",\n \"Title: A Multilevel Cholesky Conjugate Gradients Hybrid Solver For Linear Systems With Multiple Right-Hand Sides\\nYear: 2011\\n\\nAbstract: We consider the problem of repeatedly solving a large sparse linear system Ax = b for the same coefficient matrix A with a sequence of different right-hand side vectors b. We seek to develop a new tree-structured hybrid solver as an efficient alternative to Preconditioned Conjugate Gradients (PCG) based methods for this problem when A is symmetric positive definite and sparse.In this paper, our key contribution is a tree-based multilevel hybrid of direct and iterative methods using sparse Cholesky and PCG, respectively. Cholesky is applied to the leaf submatrices and PCG is applied to higher level subsystems in the tree. Partial solutions obtained thereafter are aggregated and corrected to provide the final solution. Our tree-based hybrid solution strategy seeks to couple the accuracy of a sparse direct solver with the memory efficiency of an iterative method to potentially improve overall performance for repeated solutions.We provide an empirical evaluation on a suite of 12 benchmark matrices from the University of Florida collection. Our results indicate that our tree-based hybrid solver is 1.87 times faster than most variants of PCG, among several, using different combinations of ordering, level-of-fill or threshold methods with an Incomplete Cholesky preconditioner.\",\n \"Title: Reducing energy consumption of parallel sparse matrix applications through integrated link/CPU voltage scaling\\nYear: 2007\\n\\nAbstract: Reducing power consumption is quickly becoming a first-class optimization metric for many high-performance parallel computing platforms. One of the techniques employed by many prior proposals along this direction is voltage scaling and past research used it on different components such as networks, CPUs, and memories. In contrast to most of the existent efforts on voltage scaling that target a single component (CPU, network or memory components), this paper proposes and experimentally evaluates a voltage/frequency scaling algorithm that considers CPU and communication links in a mesh network at the same time. More specifically, it scales voltages/frequencies of CPUs in the nodes and the communication links among them in a coordinated fashion (instead of one after another) such that energy savings are maximized without impacting execution time. Our experiments with several tree-based sparse matrix computations reveal that the proposed integrated voltage scaling approach is very effective in practice and brings 13% and 17% energy savings over the pure CPU and pure communication link voltage scaling schemes, respectively. The results also show that our savings are consistent with the different network sizes and different sets of voltage/frequency levels.\",\n \"Title: Similarity Graph Neighborhoods for Enhanced Supervised Classification.\\nYear: 2012\\n\\nAbstract: We consider transformations to enhance classification accuracy that are applied during the training phase of a supervised classifier with prelabeled data. We consider similarity graph neighborhoods (SGN) in the feature subspace of the training data to obtain a transformed dataset by determining displacements for each entity. Our SGN classifier is a supervised learning scheme that is trained on these transformed data; the separating boundary obtained is thereafter used for future classification. We discuss improvements in classification accuracy for an artificial dataset and present empirical results for Linear Discriminant (LD) classifier, Support Vector Machine (SVM), SGN-LD, and SGN-SVM for 6 well-known datasets from the University of California at Irvine (UCI) repository [1]. Our results indicate that on average SGN-LD improves accuracy by 5.0% and SGN-SVM improves it by 4.52%.\",\n \"Title: Markov Model Based Disk Power Management for Data Intensive Workloads\\nYear: 2009\\n\\nAbstract: In order to meet the increasing demands of present and upcoming data-intensive computer applications, there has been a major shift in the disk subsystem, which now consists of more disks with higher storage capacities and higher rotational speeds. These have made the disk subsystem a major consumer of power, making disk power management an important issue. People have considered the option of spinning down the disk during periods of idleness or serving the requests at lower rotational speeds when performance is not an issue. Accurately predicting future disk idle periods is crucial to such schemes. This paper presents a novel disk-idleness prediction mechanism based on Markov models and explains how this mechanism can be used in conjunction with a three-speed disk. Our experimental evaluation using a diverse set of workloads indicates that (i) prediction accuracies achieved by the proposed scheme are very good (87.5% on average); (ii) it generates significant energy savings over the traditional power-saving method of spinning down the disk when idle (35.5% onaverage); (iii) it performs better than a previously proposed multi-speed disk management scheme (19% on average); and (iv) the performance penalty is negligible (less than 1% on average). Overall, our implementation and experimental evaluation using both synthetic disk traces and traces extracted from real applications demonstrate the feasibility of a Markov-model-based approach to saving disk power.\",\n \"Title: Adapting Application Mapping to Systematic Within-Die Process Variations on Chip Multiprocessors\\nYear: 2009\\n\\nAbstract: Process variations, which lead to timing and power variations across identically-designed components, have been identified as one of the key future design challenges by the semiconductor industry. Using worst case latency/power assumptions is one option to address process variations. This option, while simplifying the problem, is becoming less and less attractive as its performance and power costs keep increasing. As a result, exploring options that allow the software to have knowledge about the actual latency/power consumption values is critical for future systems. Targeting systematic process variations, this paper makes two contributions. First, we discuss how we can assign threads to the cores of a chip multiprocessor (CMP) with process variations in mind and show the energy-delay product (EDP) benefits such a process variation-aware thread mapping can bring. Second, we study the benefits of varying the frequencies on a subset of the cores to increase EDP savings. We propose and evaluate integer linear programming based thread mapping schemes in both studies. While these schemes operate with profile data, they can be made to work with partial profiling as well with the help of curve fitting. We tested our schemes using both sequential and multi-threaded benchmarks from different suites and the results collected indicate that we can achieve EDP savings as much as 73.4%, with an average saving of 37.1% over a process variation agnostic scheme.\",\n \"Title: Dynamic core partitioning for energy efficiency\\nYear: 2010\\n\\nAbstract: Chip multiprocessors (CMPs) are expected to dominate the landscape of computer architecture in the near future. The potential performance gains that can be achieved by the use of CMPs depend, to a large extent, on how much parallelism can be extracted from applications. One effective way of utilizing CMP architectures is to execute multiple (potentially multi-threaded) applications at the same time. In this work, we propose and evaluate a dynamic (runtime) core partitioning scheme for CMPs that exploits application level information. Focusing on an optimization metric called the weighted energy-delay product gain (W-EDPG), we dynamically partition available cores across competing applications during the course of execution. This dynamic partitioning uses input from a curve fitting model to predict the best operating points for an application at runtime. It can generate nonuniform core allocations across applications (i.e., some applications may have more or fewer cores than others) if doing so increases the value of the W-EDPG metric. We compare this approach against several alternative schemes (including equal partitioning of cores and standard operating system based scheduling). Our experiments indicate that the proposed core partitioning scheme improves the W-EDPG metric significantly (e.g., 14.0% on average over the equal partitioning scheme on a 16-core CMP when four multi-threaded applications are executing concurrently).\",\n \"Title: Performance of Greedy Ordering Heuristics for Sparse Cholesky Factorization\\nYear: 1999\\n\\nAbstract: Greedy algorithms for ordering sparse matrices for Cholesky factorization can be based on different metrics. Minimum degree, a popular and effective greedy ordering scheme, minimizes the number of nonzero entries in the rank-1 update (degree) at each step of the factorization. Alternatively, minimum deficiency minimizes the number of nonzero entries introduced (deficiency) at each step of the factorization. In this paper we develop two new heuristics: modified minimum deficiency (MMDF) and modified multiple minimum degree (MMMD). The former uses a metric similar to deficiency while the latter uses a degree-like metric. Our experiments reveal that on the average, MMDF orderings result in 21% fewer operations to factor than minimum degree; MMMD orderings result in 15% fewer operations to factor than minimum degree. MMMD requires on the average 7--13% more time than minimum degree, while MMDF requires on the average 33--34% more time than minimum degree.\",\n \"Title: Characterizing sparse preconditioner performance for the support vector machine kernel\\nYear: 2010\\n\\nAbstract: A two-class Support Vector Machine (SVM) classifier finds a hyperplane that separates two classes of data with the maximum margin. In a first learning phase, SVM involves the construction and solution of a primal-dual interiorpoint optimization problem. Each iteration of the interior-point method (IPM) requires a sparse linear system solution, which dominates the execution time of SVM learning. Solving this linear system can often be computationally expensive depending on the conditioning of the matrix. Consequently, preconditioned linear systems can lead to improved SVM performance while maintaining the classification accuracy. In this paper, we seek to characterize the role of preconditioning schemes for enhancing the SVM classifier performance. We compare and report on the solution time, convergence, and number of Newton iterations of the iterior-point method and classification accuracy of the SVM for 6 well-accepted preconditioning schemes and datasets chosen from well-known machine learning repositories. In particular, we introduce Δ-IPM that sparsifies the linear system at each iteration of the IPM. Our results indicate that on average the Jacobi and SSOR preconditioners perform 10.01 times better than other preconditioning schemes for IPM and 8.83 times better for Δ-IPM. Also, across all datasets Jacobi and SSOR perform between 2 to 30 times better than other schemes in both IPM and Δ-IPM. Moreover, Δ-IPM obtains a speedup over IPM performance on average by 1.25 and as much as 2 times speedup in the best case.\",\n \"Title: Co-Scheduling Algorithms for High-Throughput Workload Execution\\nYear: 2013\\n\\nAbstract: This paper investigates co-scheduling algorithms for processing a set of parallel applications. Instead of executing each application one by one, using a maximum degree of parallelism for each of them, we aim at scheduling several applications concurrently. We partition the original application set into a series of packs, which are executed one by one. A pack comprises several applications, each of them with an assigned number of processors, with the constraint that the total number of processors assigned within a pack does not exceed the maximum number of available processors. The objective is to determine a partition into packs, and an assignment of processors to applications, that minimize the sum of the execution times of the packs. We thoroughly study the complexity of this optimization problem, and propose several heuristics that exhibit very good performance on a variety of workloads, whose application execution times model profiles of parallel scientific codes. We show that co-scheduling leads to faster workload completion time (40 % improvement on average over traditional scheduling) and to faster response times (50 % improvement). Hence, co-scheduling increases system throughput and saves energy, leading to significant benefits from both the user and system perspectives.\",\n \"Title: Towards A Scalable Hybrid Sparse Solver\\nYear: 2000\\n\\nAbstract: Consider the solution of very large, sparse linear systems, The most popular techniques can be broadly classified as either 'direct' or 'iterative', When the sparse matrix is symmetric and positive definite, direct methods use Cholesky factorization while iterative methods rely on Conjugate Gradients, Our goal is to develop a scalable and memory-efficient hybrid of the two methods that can be implemented with high efficiency on both serial and parallel computers and be suitable for a wide range of problems. We discuss our overall design with emphasis on performance and scalability issues, and report on progress to date. Copyright (C) 2000 John Wiley & Sons, Ltd.\",\n \"Title: Speedup-Aware Co-Schedules For Efficient Workload Management\\nYear: 2013\\n\\nAbstract: Many HPC systems run workloads comprising scientific simulations where the problem size is often fixed while model parameters are changed for each run. The speedup pro file of such applications can often be determined using data from previous runs. Many applications exhibit sublinear speedups and thus only incremental improvements in ex ecution time when larger numbers of processors are used. In this paper, we consider a workload of applications queued for execution and co-schedules that can exploit speedup profiles. More specifically, we seek co-schedules to reduce workload completion time (i.e., makespan), and total energy consumed by the system. Additionally, we explore how co schedules may reduce average application turnaround time and thus benefit the user. We propose speedup-aware processor partitioning (SAPP) co-scheduling schemes, including optimal and greedy variants. We show that our greedy co-schedules reduce system energy, workload makespan and average application turnaround time when compared to a base scheme that runs each application on all available processors. Our experiments demonstrate that on a system with 128 processors, on average, our SAPP-greedy co schedules can reduce makespan and turnaround time by 20% and decrease total energy consumed by 40%.\",\n \"Title: Characterizing the impact of soft errors on iterative methods in scientific computing\\nYear: 2011\\n\\nAbstract: The increase in on-chip transistor count facilitates achieving higher performance, but at the expense of higher susceptibility to soft errors. In this paper, we characterize the challenges posed by soft errors for large-scale applications representative of workloads on supercomputing systems. Such applications are typically based on the computational solution of partial differential equation models using either explicit or implicit methods. In both cases, the execution time of such applications is typically dominated by the time spent in their underlying sparse matrix vector multiplication kernel (SpMV, t ← A • y). We provide a theoretical analysis of the impact of a single soft error through its propagation by a sequence of sparse matrix vector multiplication operations. Our analysis indicates that a single soft error in some ith component of the vector y can corrupt the entire resultant vector in a relatively short sequence of SpMV operations. Additionally, the propagation pattern corresponds to the sparsity structure of the coefficient matrix A and the magnitude of the error grows non-linearly as(||Ai||2∗)k, after k SpMV operations, where, ||Ai∗||2 is the 2-norm of the ith row of A. We corroborate this analysis with empirical observations on a model heat equation using explicit method and well known sparse matrix systems (matrices from a test suite) for the implicit method using iterative solvers such as CG, PCG and SOR. Our results indicate that explicit schemes will suffer from soft error induced numerical instabilities, thus exacerbating intrinsic stability issues for such methods, that impose constraints on relative time and space step sizes. For implicit schemes, linear solver performance through widely used CG and PCG schemes, degrades by a factor as high as 200x, whereas, a stationary scheme such as SOR is inherently soft error resilient. Our results thus indicate the need for new approaches to achieve soft error resiliency in such methods and a critical evaluation of the tradeoffs among multiple metrics, including, performance, reliability and energy.\",\n \"Title: Ring Data Location Prediction Scheme For Non-Uniform Cache Architectures\\nYear: 2008\\n\\nAbstract: Increases in cache capacity are accompanied by growing wire delays due to technology scaling. Non-Uniform Cache Architecture (NUCA) is one of proposed solutions to reducing the average access latency in such cache designs. While most of the prior NUCA work focuses on data placement, data replacement, and migration related issues, this paper studies the problem of data search (access) in NUCA. In our architecture we arrange sets of banks with equal access latency into rings. Our Last Access Based (LAB) prediction scheme predicts the ring that is expected to contain the required data and checks the banks in that ring first for the data block sought. We compare our scheme to two alternate approaches: searching all rings in parallel, and searching rings sequentially. We show that our LAB ring prediction scheme reduces L2 energy significantly over the sequential and parallel schemes, while maintaining similar performance. Our LAB scheme reduces energy consumption by 15.9% relative to the sequential lookup scheme, and 53.8% relative to the parallel lookup scheme.\",\n \"Title: Level search schemes for information filtering and retrieval\\nYear: 2001\\n\\nAbstract: Latent semantic indexing (LSI) has been demonstrated to outperform lexical matching in information retrieval. However, the enormous cost associated with the singular value decomposition (SVD) of the large term-by-document matrix becomes a barrier for its application to scalable information retrieval. This work shows that information filtering using level search techniques can reduce the SVD computation cost for LSI. For each query, level search extracts a much smaller subset of the original term-by-document matrix, containing on average 27% of the original non-zero entries. When LSI is applied to such subsets, the average precision can degrade by as much as 23% due to level search filtering. However, for some document collections an increase in precision has also been observed. Further enhancement of level search can be based on a pruning scheme which deletes terms connected to only one document from the query-specific submatrix. Such pruning has achieved a 65% reduction (on average) in the number of non-zeros with a precision loss of 5% for most collections.\",\n \"Title: Phase Partitioning Methods for I/O Cache Optimization\\nYear: 2012\\n\\nAbstract: System designers face large challenges in the storage hierarchy when putting new optimizations into practice. We consider a recent storage cache optimization, designed to reduce cache requirements and boost I/O performance, which adapts to individual program behavior. This scheme leverages a quantum-based design, and we observe that the choice of time quanta has a significant effect on performance and overheads. Accordingly, intelligent designs must judiciously select re-optimization points. We therefore develop new phase detection schemes that identify valued re-optimization points through interaction models between applications and this caching technique. We evaluate online and offline variants in the context of enterprise I/O workloads and observe hit-rate gains over 20% for a range of cache sizes.\",\n \"Title: Interference Resolver in Shared Storage Systems to Provide Fairness to I/O Intensive Applications\\nYear: 2013\\n\\nAbstract: Most of the prior mechanisms on managing shared storage resources manage each individual shared resource without considering the interplay between different resources, leading to low fairness and loss of performance. Therefore, a coordinated mechanism that provides fairness in the entire shared storage system is desirable. This paper proposes a strategy to control inter-application interference by dynamically adjusting the aggressiveness of the shared storage cache and I/O bandwidth accesses made by multiple, concurrently-executing applications, in a coordinated fashion. Our interference resolver eliminates the need for complicated individual resource-based partitioning mechanisms implemented independently in each resource and that require coordination. It ensures fairness among high performance applications that access the underlying storage system, while best utilizing the available resources. In our experimental evaluation, we use both trace-driven simulations and an implementation in the Linux kernel 2.6.32, and show that our interference resolver can significantly increase system performance and provide fairness to concurrently-executing applications.\",\n \"Title: Ring Prediction for Non-Uniform Cache Architectures\\nYear: 2007\\n\\nAbstract: Increasing wire delays and memory capacities motivate new ways of designing L2 and L3 caches. NUCA (Non-Uniform Cache Architecture) has received considerable attention in the last few years. While most of the prior NUCA-based efforts have focused on data placement, data replacement, and migration related issues, this paper studies the problem of data search. Specifically, it proposes and experimentally evaluates several data search schemes for NUCA L2 caches that exhibit different performance-power trade-offs. These schemes are based on predicting the next ring (set of banks) to be accessed in a NUCA L2, and checking the banks in that ring first. In this work, we present the details of these prediction schemes, and compare them to two alternate approaches: searching all rings in parallel, and searching rings sequentially, starting with the one that is closest to the CPU.\",\n \"Title: Towards Low-Cost, High-Accuracy Classifiers for Linear Solver Selection\\nYear: 2009\\n\\nAbstract: The time to solve linear systems depends to a large extent on the choice of the solution method and the properties of the coefficient matrix. Although there are several linear solution methods, in most cases it is impossible to predict apriori which linear solver would be best suited for a given linear system. Recent investigations on selecting linear solvers for a given system have explored the use of classification techniques based on the linear system parameters for solver selection. In this paper, we present a method to develop low-cost high-accuracy classifiers. We show that the cost for constructing a classifier can be significantly reduced by focusing on the computational complexity of each feature. In particular, we filter out low information linear system parameters and then order the remaining parameters to decrease the total computation cost for classification at a prescribed accuracy. Our results indicate that the speedup factor of the time to compute the feature set using our ordering can be as high as 262. The accuracy and computation time of the feature set generated using our method is comparable to a near-optimal one, thus demonstrating the effectiveness of our technique.\",\n \"Title: Hybrid Techniques for Fast Multicore Simulation\\nYear: 2009\\n\\nAbstract: One of the challenges in the design of multicore architectures concerns the fast evaluation of hardware design-tradeoffs using simulation techniques. Simulation tools for multicore architectures tend to have long execution times that grow linearly with the number of cores simulated. In this paper, we present two hybrid techniques for fast and accurate multicore simulation. Our first method, the Monte Carlo Co-Simulation (MCCS) scheme, considers application phases, and within each phase, interleaves a Monte Carlo modeling scheme with a traditional simulator, such as Simics. Our second method, the Curve Fitting Based Simulation (CFBS) scheme, is tailored to evaluate the behavior of applications with multiple iterations, such as scientific applications that have consistent cycles per instruction (CPI) behavior within a subroutine over different iterations. In our CFBS method, we represent the CPI profile of a subroutine as a signature using curve fitting and represent the entire application execution as a set of signatures to predict performance metrics. Our results indicate that MCCS can reduce simulation time by as much as a factor of 2.37, with a speedup of 1.77 on average compared to Simics. We also observe that CFBS can reduce simulation time by as much as a factor of 13.6, with a speedup of 6.24 on average. The observed average relative errors in CPI compared to Simics are 32% for MCCS and significantly lower, at 2%, for CFBS.\",\n \"Title: Link Shutdown Opportunities During Collective Communications in 3-D Torus Nets\\nYear: 2007\\n\\nAbstract: As modern computing clusters used in scientific computing applications scale to ever-larger sizes and capabilities, their operational energy costs have be- come prohibitive. While it is an emerging trend in modern cluster design to optimize for low energy consumption in the individual computational nodes, little attention has been paid to reducing the energy used by the communication network that connects the nodes. In this work. we consider a 3-D torus network similar to the one in BlueGene/L to ex- plore opporunities for link shutdown during collec- tive communication operations. For example, we demonstrate that in the case of all-to-one reduce codes, approximately 99% of the total network link time can be spent in a shutoff state on a 64-node toroidal network, thus reducing the overall system energy by approximately 15-28%\",\n \"Title: Parallel Hybrid Preconditioning: Incomplete Factorization with Selective Sparse Approximate Inversion\\nYear: 2010\\n\\nAbstract: We consider parallel preconditioning to solve large sparse linear systems $Ax=b$ using conjugate gradients when $A$ is symmetric and positive definite. We develop a preconditioner that can be viewed as a hybrid of incomplete factorization and sparse approximate inversion schemes. Such a hybrid can potentially enable fast and reliable solution through a preconditioner with low memory requirements that allows latency-tolerant construction and application on multiprocessor systems. We propose a parallel hybrid scheme which yields a preconditioner as a tree-structured aggregate of sparse incomplete factors and inverses of selected submatrices. We analyze the computation and communication costs of our hybrid preconditioner and report on its parallel performance on some well-known test matrices. Our results indicate that our hybrid has significant advantages over sparse approximate inverse preconditioners and incomplete Cholesky preconditioners using either drop-threshold or zero-level-of-fill schemes.\",\n \"Title: Time-memory trade-offs using sparse matrix methods for large-scale eigenvalue problems\\nYear: 2003\\n\\nAbstract: Iterative methods such as Lanczos and Jacobi-Davidson are typically used to compute a small number of eigenvalues and eigenvectors of a sparse matrix. However, these methods are not effective in certain large-scale applications, for example, \\\"global tight binding molecular dynamics.\\\" Such applications require all the eigenvectors of a large sparse matrix; the eigenvectors can be computed a few at a time and discarded after a simple update step in the modeling process. We show that by using sparse matrix methods, a direct-iterative hybrid scheme can significantly reduce memory requirements while requiring less computational time than a banded direct scheme. Our method also allows a more scalable parallel formulation for eigenvector computation through spectrum slicing. We discuss our method and provide empirical results for a wide variety of sparse matrix test problems.\",\n \"Title: Fault tolerant preconditioned conjugate gradient for sparse linear system solution\\nYear: 2012\\n\\nAbstract: In scientific applications that involve dense matrices, checksum encodings have yielded \\\"algorithm-based fault tolerance\\\" (ABFT) in the event of data corruption from either hard or transient (soft) errors in the hardware. However, such checksum-based ABFT techniques have not been developed when sparse matrices are involved, for example, in sparse linear system solution through a method such as preconditioned conjugate gradients (PCG). In this paper, we develop a new sparse checksum encoded algorithm-based fault tolerant PCG, S-ABFT-PCG. Our checksum based approach can be applied to all the key operations in PCG, including sparse matrix-vector multiplication (SpMV), vector operations and the application of a preconditioner through sparse triangular solution. We prove that our approach detects a single error in the matrix and vector elements and in the metadata representing the sparse matrix row or column indices, when the linear system has a coefficient matrix that is symmetric positive definite and strictly diagonally dominant. The overhead of S-ABFT-PCG is proportional to the cost of a few O(n) vector operations, a value that is relatively low compared to the total cost of a PCG iteration with an SpMV and two triangular solutions. However, if an error is detected, then the underlying PCG iteration must be recomputed because our approach does not enable checksum encoded recovery from the error. We compare our S-ABFT-PCG with a classical ABFT-PCG (C-ABFT-PCG) that detects and recovers from a single error in the SpMV kernel, but does not provide fault tolerance for the sparse triangular solution kernel. Our experimental results indicate that in the event of no errors, compared to a PCG with no ABFT, the overheads of S-ABFT-PCG are 11.3% and lower than the 23.1% overheads of C-ABFT-PCG. Furthermore, in the event of a single error in the application of the preconditioner through triangular solution, C-ABFT-PCG suffers from significant increases in iteration counts, leading to performance degradations of 63.2% on average compared to 3.2% on average for S-ABFT-PCG.\",\n \"Title: Large-Scale Normal Coordinate Analysis On Distributed Memory Parallel Systems\\nYear: 2002\\n\\nAbstract: A parallel computational scheme for analyzing large-scale molecular vibration on distributed memory computing platforms is presented in this paper. This method combines the implicitly restarted Lanczos algorithm with a state-of-art parallel sparse direct solver to compute a set of low frequency vibrational modes for molecular systems containing tens of thousands of atoms. Although the original motivation for developing such a scheme was to overcome memory limitations on traditional sequential and shared memory machines, our computational experiments show that with a careful parallel design and data partitioning scheme one can achieve scalable performance on lightly coupled distributed memory parallel systems. In particular, we demonstrate performance enhancement achieved by using the latency tolerant \\\"selective inversion\\\" scheme in the sparse triangular substitution phase of the computation.\",\n \"Title: Incomplete Cholesky Parallel Preconditioners with Selective Inversion\\nYear: 1999\\n\\nAbstract: Consider the solution of a large linear system when the coe cient matrix is sparse, symmetric, and positive de nite. One approach is the method of \\\\conjugate gradient\\\" (CG) with an incomplete Cholesky (IC) preconditioner (ICCG). A key problem with the design of a parallel ICCG solver is the bottleneck posed by repeated parallel sparse triangular solves to apply the preconditioner. Our work concerns the use of \\\\selective inversion\\\" techniques to replace parallel substitution schemes (for triangular solution) by e cient, scalable matrix-vector multiplication. We report on the performance of our parallel solver by summarizing results of experiments on both SMPs and message-passing multiprocessors.\",\n \"Title: Poster reception - Toward a power efficient computer architecture for Barnes-Hut N-body simulations\\nYear: 2006\\n\\nAbstract: Recent improvements in processor performance have been accompanied by increased chip complexity and power consumption, resulting in increased heat dissipation. This has resulted in higher cooling costs and lower reliability. In this paper, we focus on power-aware high performance scientific computing and in particular the Barnes-Hut (BH) code that is used for N-body problems. We show how low power modes of the CPU and caches, and hardware optimizations such as a load miss predictor and data prefetchers enable BH to operate at lower power configurations with out performance degradation. On our optimized processor, power is reduced by 57% and energy is reduced by 58% with no performance penalty using simulations with SimpleScalar and Wattch. Consequently, the energy efficiency of the processor increases by a factor of more than two when compared to the base architecture.\",\n \"Title: Parallel hybrid sparse solvers through flexible incomplete cholesky preconditioning\\nYear: 2004\\n\\nAbstract: We consider parallel preconditioning schemes to accelerate the convergence of Conjugate Gradients (CG) for sparse linear system solution. We develop methods for constructing and applying preconditioners on multiprocessors using incomplete factorizations with selective inversion for improved latency-tolerance. We provide empirical results on the efficiency, scalability and quality of our preconditioners for sparse matrices from model grids and some problems from practical applications. Our results indicate that our preconditioners enable more robust sparse linear system solution.\",\n \"Title: On improving performance and energy profiles of sparse scientific applications\\nYear: 2006\\n\\nAbstract: In many scientific applications, the majority of the execution time is spent within a few basic sparse kernels such as sparse matrix vector multiplication (SMV). Such sparse kernels can utilize only a fraction of the available processing speed because of their relatively large number of data accesses per floating point operation, and limited data locality and data re-use. Algorithmic changes and tuning of codes through blocking and loop unrolling schemes can improve performance but such tuned versions are typically not available in benchmark suites such as the SPEC CFP 2000. In this paper, we consider sparse SMV kernels with different levels of tuning that are representative of this application space. We emulate certain memory subsystem optimizations using SimpleScalar and Wattch to evaluate improvements in performance and energy metrics. We also characterize how such an evaluation can be affected by the interplay between code tuning and memory subsystem optimizations. Our results indicate that the optimizations reduce execution time by over 40%, and the energy by over 85%, when used with power control modes of CPUs and caches. Furthermore, the relative impact of the same set of memory subsystem optimizations can vary significantly depending on the level of code tuning. Consequently, it may be appropriate to augment traditional benchmarks by tuned kernels typical of high performance sparse scientific codes to enable comprehensive evaluations of future systems.\",\n \"Title: Characterizing the performance and energy attributes of scientific simulations\\nYear: 2006\\n\\nAbstract: We characterize the performance and energy attributes of scientific applications based on nonlinear partial differential equations (PDEs). where the dominant cost is that of sparse linear system solution. We obtain performance and energy metrics using cycle-accurate emulations on a processor and memory system derived from the PowerPC RISC architecture with extensions to resemble the processor in the BlueGene/L. These results indicate that low-power modes of CPUs such as Dynamic Voltage Scaling (DVS) can indeed result in energy savings at the expense of performance degradation. We then consider the impact of certain memory subsystem optimizations to demonstrate that these optimizations in conjunction with DVS can provide faster execution time and lower energy consumption. For example, on the optimized architecture, if DVS is used to scale down the processor to 600MHz, execution times are faster by 45% with energy reductions of 75% compared to the original architecture at 1GHz. The insights gained from this study can help scientific applications better utilize the low-power modes of processors as well as guide the selection of hardware optimizations in future power-aware, high-performance computers.\",\n \"Title: Phase-aware adaptive hardware selection for power-efficient scientific computations\\nYear: 2007\\n\\nAbstract: Increased power consumption and heat dissipation have become the major limiters of available computational resources at many high performance computing (HPC) centers. Applications that run at such centers typically operate in single user mode, run for long periods of time, and have long lasting application phases. Their users are interested in obtaining the maximum performance. We propose a phase aware adaptive hardware selection technique, featuring data prefetchers and dynamic voltage and frequency scaling. Our technique takes advantage of memory bound phases in scientific codes, resulting in significant power (39%) and energy (37%) reductions while maintaining or exceeding the performance of an unoptimized system.\",\n \"Title: Intra-application shared cache partitioning for multithreaded applications\\nYear: 2010\\n\\nAbstract: In this paper, we address the problem of partitioning a shared cache when the executing threads belong to the same application.\",\n \"Title: PFFTC: An improved fast Fourier transform for the IBM cell broadband engine\\nYear: 2010\\n\\nAbstract: The Fast Fourier Transform (FFT) is a widely used algorithm that is frequently employed in environments where high performance is critical. In the context of embedded systems, FFTs often have hard runtime constraints and must be evaluated using limited hardware. In this paper, we present a partitioned FFT algorithm (PFFTC) for the Cell Broadband Engine ( Cell BE) that improves upon previous FFT implementations for this platform. PFFTC has three main phases to (i) partition the problem into independent sub-problems, (ii) solve the sub-problems in parallel, and (iii) combine the results of the sub-problems to obtain the solution to the original problem. PFFTC includes optimizations for exploiting data transfer parallelism, avoiding unnecessary communication through careful data routing, avoiding data dependency stalls with instruction-level double buffering, and minimizing synchronization overhead through the use of an \\\"asynchronous\\\" single-based barrier. We evaluate the performance of PFFTC and other FFT algorithms for the Cell BE. Our results indicate that PFFTC attains a peak processing rate 33.6 GFLOPS, and achieves speedups ranging form 31% to 62% over the previous Cell BE FFT algorithm's reported performance for complex single-precision FETs with 1,024-16,384 data points. (C) 2010 Published by Elsevier Ltd.\",\n \"Title: Virtual I/O caching: dynamic storage cache management for concurrent workloads\\nYear: 2011\\n\\nAbstract: A leading cause of reduced or unpredictable application performance in distributed systems is contention at the storage layer, where resources are multiplexed among many concur rent data intensive workloads. We target the shared storage cache, used to alleviate disk I/O bottlenecks, and propose a new caching paradigm to both improve performance and reduce memory requirements for HPC storage systems. We present the virtual I/O cache, a dynamic scheme to manage a limited storage cache resource. Application behavior and the corresponding performance of a chosen replacement policy are observed at run time, and a mechanism is designed to mitigate suboptimal behavior and increase cache efficiency. We further use the virtual I/O cache to isolate concurrent workloads and globally manage physical resource allocation towards system level performance objectives. We evaluate our scheme using twenty I/O intensive applications and benchmarks. Average hit rate gains over 17% were observed for isolated workloads, as well as cache size reductions near 80% for equivalent performance levels. Our largest concurrent workload achieved hit rate gains over 23%, and an over 80% iso-performance cache reduction.\",\n \"Title: Can models of scientific software-hardware interactions be predictive?\\nYear: 2011\\n\\nAbstract: Sparse scientific codes face grave performance challenges as memory bandwidth limitations grow on multi-core architectures. We investigate the memory behavior of a key sparse scientific kernel and study model-driven performance evaluation in this scope. We propose the Coupled Reuse-Cache Model (CRC Model), to enable multilevel cache performance analysis of parallel sparse codes. Our approach builds separate probabilistic application and hardware models, which are coupled to discover unprecedented insight into software-hardware interactions in the cache hierarchy. We evaluate our model's predictive performance with the pervasive sparse matrix-vector product kernel, using 1 to 16 cores and multiple cache configurations. For multi-core setups, average L1 and L2 prediction errors are within 3% and 6% respectively.\",\n \"Title: Effective Preconditioning through Ordering Interleaved with Incomplete Factorization\\nYear: 2006\\n\\nAbstract: Consider an incomplete Cholesky factorization of a sparse symmetric positive definite matrix. It is common practice to start with a symmetric permutation of the rows and columns of the matrix using an ordering to reduce fill in the complete Cholesky factor. Such an approach has two drawbacks. First, such an ordering is designed to reduce fill or operation counts in the complete Cholesky factor, and thus does not necessarily address the issue of controlling fill or operation counts during incomplete factorization. Second, because the ordering is determined in advance of the incomplete factorization, it is not easy to accommodate alternative pivoting sequences, for example, using numeric measures to promote stability, while taking into account their impact on fill and operation counts. In this paper, we consider an alternative approach that interleaves ordering with numeric computation in an incomplete Cholesky factorization. Such an interleaved scheme controls fill and operation counts. It also allows the incorporation of some limited, pivot selection strategies for stability. We demonstrate through experiments that our interleaved minimum-degree approach leads to fewer failures during incomplete factorization and improved convergence when the incomplete factor is used as a preconditioner for the conjugate gradient method. We conjecture that the improvements in the quality of preconditioning arise from the ability of our method to generate better approximations to the complete factor.\",\n \"Title: A Combinatorial Scheme for Developing Efficient Composite Solvers\\nYear: 2002\\n\\nAbstract: Many fundamental problems in scientific computing have more than one solution method. It is not uncommon for alternative solution methods to represent different tradeoffs between solution cost and reliability. Furthermore, the performance of a solution method often depends on the numerical properties of the problem instance and thus can vary dramatically across application domains. In such situations, it is natural to consider the construction of a multi-method composite solver to potentially improve both the average performance and reliability. In this paper, we provide a combinatorial framework for developing such composite solvers. We provide analytical results for obtaining an optimal composite from a set of methods with normalized measures of performance and reliability. Our empirical results demonstrate the effectiveness of such optimal composites for solving large, sparse linear systems of equations.\",\n \"Title: Exploiting dense substructures for fast sparse matrix vector multiplication\\nYear: 2011\\n\\nAbstract: The execution time of many scientific computing applications is dominated by the time spent in performing sparse matrix vector multiplication (SMV; y â聠聬 A 脗· x). We consider improving the performance of SMV on multicores by exploiting the dense substructures that are inherently present in many sparse matrices derived from partial differential equation models. First, we identify indistinguishable vertices, i.e., vertices with the same adjacency structure, in a graph representation of the sparse matrix (A) and group them into a supernode. Next, we identify effectively dense blocks within the matrix by grouping rows and columns in each supernode. Finally, by using a suitable data structure for this representation of the matrix, we reduce the number of load operations during SMV while exactly preserving the original sparsity structure of A. In addition, we use ordering techniques to enhance locality in accesses to the vector, x, to yield an SMV kernel that exploits the effectively dense substructures in the matrix. We evaluate our scheme on Intel Nehalem and AMD Shanghai processors. We observe that for larger matrices on the Intel Nehalem processor, our method improves performance on average by 37.35% compared with the traditional compressed sparse row scheme (a blocked compressed form improves performance on average by 30.27%). Benefits of our new format are similar for the AMD processor. More importantly, if we pick for each matrix the best among our method and the blocked compressed scheme, the average performance improvements increase to 40.85%. Additional results indicate that the best performing scheme varies depending on the matrix and the system. We therefore propose an effective density measure that could be used for method selection, thus adding to the variety of options for an auto-tuned optimized SMV kernel that can exploit sparse matrix properties and hardware attributes for high performance.\",\n \"Title: Analysis of the IPv4 Address Space Delegation Structure\\nYear: 2007\\n\\nAbstract: The Internet has grown tremendously in terms of the number of users who rely on it and the number of orga- nizations that are connected to it. Characterizing how this growth affects its structure and topology is vitally impor- tant to determine the fundamental characteristics and limi- tations that must be handled, such as address space exhaus- tion; understanding the process of allocating and delegat- ing address space can help to answer these questions. In this paper, we analyze BGP routing data to study the struc- ture and growth of IPv4 address space allocation, fragmen- tation and usage. We explore the notion of delegation rela- tionships among prefixes and use this information to con- struct an autonomous system (AS) delegation tree. We show that delegation in the Internet is not significantly correlated to the underlying topology or AS customer-provider rela- tionships. We also analyze the fragmentation and usage of address space over a period of five years and examine pre- fixes that are delegated by organizations vs. those that are not delegated. We notice that the address space usage due to delegating prefixes is increasing at the same rate as the ad- dress space usage due to non-delegating prefixes. This indi- cates that fragmentation rate of the address space is actu- ally almost a constant with respect to total address usage. Additionally, we show that most delegation is performed by a small number of organizations, which may aid in the im- plementation of a public-key infrastructure for the Internet.\",\n \"Title: Adapting Sparse Triangular Solution to GPUs\\nYear: 2012\\n\\nAbstract: High performance computing systems are increasingly incorporating hybrid CPU/GPU nodes to accelerate the rate at which floating point calculations can be performed for scientific applications. Currently, a key challenge is adapting scientific applications to such systems when the underlying computations are sparse, such as sparse linear solvers for the simulation of partial differential equation models using semi-implicit methods. Now, a key bottleneck is sparse triangular solution for solvers such as preconditioned conjugate gradients (PCG). We show that sparse triangular solution can be effectively mapped to GPUs by extracting very large degrees of fine-grained parallelism using graph coloring. We develop simple performance models to predict these effects at intersection of the data and hardware attributes and we evaluate our scheme on a Nvidia Tesla M2090 GPU relative to the level set scheme developed at NVIDIA. Our results indicate that our approach significantly enhances the available fine-grained parallelism to speed-up PCG iteration time compared to the NVIDIA scheme, by a factor with a geometric mean of 5.41 on a single GPU, with speedups as high as 63 in some cases.\",\n \"Title: T-NUCA - a novel approach to non-uniform access latency cache architectures for 3D CMPs\\nYear: 2010\\n\\nAbstract: We consider a non-uniform access latency cache architecture (NUCA) design for 3D chip multi-processors (CMPs) where cache structures are divided into small banks interconnected by a network-on-chip (NoC). In earlier NUCA designs, data is placed in banks either statically (S-NUCA) or dynamically (D-NUCA). In both S-NUCA and D-NUCA designs, scaling to hundreds of cores can pose several challenges. Thus, we propose a new NUCA architecture with an inclusive, octal tree-based, hierarchical directory (T-NUCA-8), with the potential to scale to hundreds of cores with performance comparable to D-NUCA at a fraction of the energy cost. Our evaluations indicate that relative to D-NUCA, our T-NUCA-8 reduces network usage by 92%, energy by 87%, and EDP by 87%, at performance cost of 10%.\",\n \"Title: Analyzing the soft error resilience of linear solvers on multicore multiprocessors\\nYear: 2010\\n\\nAbstract: As chip transistor densities continue to increase, soft errors (bit flips) are becoming a significant concern in networked multiprocessors with multicore nodes. Large cache structures in multicore processors are especially susceptible to soft errors as they occupy a significant portion of the chip area. In this paper, we consider the impacts of soft errors in caches on the resilience and energy efficiency of sparse linear solvers. In particular, we focus on two widely used sparse iterative solvers, namely Conjugate Gradient (CG) and Generalized Minimum Residuals (GMRES). We propose two adaptive schemes, (i) a Write Eviction Hybrid ECC (WEH-ECC) scheme for the L1 cache and (ii) a Prefetcher Based Adaptive ECC (PBA-ECC) scheme for the L2 cache, and evaluate the energy and reliability trade-offs they bring in the context of GMRES and CG solvers. Our evaluations indicate that WEH-ECC reduces the CG and GMRES soft error vulnerability by a factor of 18 to 220 in L1 cache, relative to an unprotected L1 cache, and energy consumption by 16%, relative to a cache with strong protection. The PBA-ECC scheme reduces the CG and GMRES soft error vulnerability by a factor of 9 Ã 103 to 8.6 Ã 109, relative to an unprotected L2 cache, and reduces the energy consumption by 8.5%, relative to a cache with strong ECC protection. Our energy overheads over unprotected L1 and L2 caches are 5% and 14% respectively.\",\n \"Title: Intra-application cache partitioning\\nYear: 2010\\n\\nAbstract: Efficient management of shared on-chip resources such as the shared level 2 (L2) cache has become an important problem with the emergence of chip multiprocessors (CMPs). Partitioning the shared cache in chip multiprocessors (CMPs) among concurrently executing applications can provide important benefits such as throughput improvement, fairness guarantees, and quality of service (QoS) enhancements. In this paper, we pose an interesting related question, which is, if partitioning the shared cache space among concurrently executing threads of the same application can enhance the application performance. We address this problem by identifying and speeding up the slowest thread, also termed as the critical path thread, during each execution interval since the overall performance of a multithreaded application is determined by the critical path thread. To do so, we propose a dynamic, runtime system based, cache partitioning scheme that partitions the shared cache space dynamically among the individual threads of a given application. In a nutshell, we wish to take some cache space away from the faster threads and give it to the critical path thread at each execution interval. We show that speeding up the critical path thread this way, results in overall performance enhancement of the application execution in the long term. Our experimental evaluation indicates that, the proposed dynamic cache partitioning scheme yields benefits up to 15% over a shared cache with no partitions, up to 23% over a statically partitioned cache (private cache) and up to 20% over a throughput-oriented scheme.\",\n \"Title: NUMA-aware graph mining techniques for performance and energy efficiency\\nYear: 2012\\n\\nAbstract: We investigate dynamic methods to improve the power and performance profiles of large irregular applications on modern multi-core systems. In this context, we study a large sparse graph application, Betweenness Centrality, and focus on memory behavior as core count scales. We introduce new techniques to efficiently map the computational demands onto non-uniform memory architectures (NUMA). Our dynamic design adapts to hardware topology and dramatically improves both energy and performance. These gains are more significant at higher core counts. We implement a scheme for adaptive data layout, which reorganizes the graph after observing parallel access patterns, and a dynamic task scheduler that encourages shared data between neighboring cores. We measure performance and energy consumption on a modern multi-core machine and observe that mean execution time is reduced by 51.2% and energy is reduced by 52.4%.\",\n \"Title: STS-k: a multilevel sparse triangular solution scheme for NUMA multicores\\nYear: 2015\\n\\nAbstract: We consider techniques to improve the performance of parallel sparse triangular solution on non-uniform memory architecture multicores by extending earlier coloring and level set schemes for single-core multiprocessors. We develop STS-k, where k represents a small number of transformations for latency reduction from increased spatial and temporal locality of data accesses. We propose a graph model of data reuse to inform the development of STS-k and to prove that computing an optimal cost schedule is NP-complete. We observe significant speed-ups with STS-3 on 32-core Intel Westmere-Ex and 24-core AMD `MagnyCours' processors. Incremental gains solely from the 3-level transformations in STS-3 for a fixed ordering, correspond to reductions in execution times by factors of 1.4(Intel) and 1.5(AMD) for level sets and 2(Intel) and 2.2(AMD) for coloring. On average, execution times are reduced by a factor of 6(Intel) and 4(AMD) for STS-3 with coloring compared to a reference implementation using level sets.\",\n \"Title: Phase Detection with Hidden Markov Models for DVFS on Many-Core Processors\\nYear: 2015\\n\\nAbstract: The energy concerns of many-core processors are increasing with the number of cores. We provide a new method that reduces energy consumption of an application on many-core processors by identifying unique segments to apply dynamic voltage and frequency scaling (DVFS). Our method, phase-based voltage and frequency scaling (PVFS), hinges on the identification of phases, i.e., Segments of code with unique performance and power attributes, using hidden Markov Models. In particular, we demonstrate the use of this method to target hardware components on many-core processors such as Network-on-Chip (NoC). PVFS uses these phases to construct a static power schedule that uses DVFS to reduce energy with minimal performance penalty. This general scheme can be used with a variety of performance and power metrics to match the needs of the system and application. More importantly, the flexibility in the general scheme allows for targeting of the unique hardware components of future many-core processors. We provide an in-depth analysis of PVFS applied to five threaded benchmark applications, and demonstrate the advantage of using PVFS for 4 to 32 cores in a single socket. Empirical results of PVFS show a reduction of up to 10.1% of total energy while only impacting total time by at most 2.7% across all core counts. Furthermore, PVFS outperforms standard coarse-grain time-driven DVFS, while scaling better in terms of energy savings with increasing core counts.\",\n \"Title: A multilevel compressed sparse row format for efficient sparse computations on multicore processors\\nYear: 2014\\n\\nAbstract: We seek to improve the performance of sparse matrix computations on multicore processors with non-uniform memory access (NUMA). Typical implementations use a bandwidth reducing ordering of the matrix to increase locality of accesses with a compressed storage format to store and operate only on the non-zero values. We propose a new multilevel storage format and a companion ordering scheme as an explicit adaptation to map to NUMA hierarchies. More specifically, we propose CSR-k, a multilevel form of the popular compressed sparse row (CSR) format for a multicore processor with k > 1 well-differentiated levels in the memory subsystem. Additionally, we develop Band-k, a modified form of a traditional bandwidth reduction scheme, to convert a matrix represented in CSRto our proposed CSR-k. We evaluate the performance of the widely-used and important sparse matrix-vector multiplication (SpMV) kernel using CSR-2 on Intel Westmere processors for a test suite of 12 large sparse matrices with row densities in the range 3 to 45. On 32 cores, on average across all matrices in the test suite, the execution time for SpMV with CSR-2is less than 42% of the time taken by the state-of-the-art automatically tuned SpMV resulting in energy savings of approximately 56%. Additionally, on average, the parallel speed-up on 32 cores of the automatically tuned SpMV relative to its 1-core performance is 8.18 compared to a value of 19.71 for CSR-2. Our analysis indicates that the higher performance of SpMV with CSR-2 comes from achieving higher reuse of x in the shared L3 cache without incurring overheads from fill-in of original zeroes. Furthermore, the pre-processing costs of SpMV with CSR-2 can be amortized on average over 97 iterations of SpMV using CSR and are substantially lower than the 513 iterations required for the automatically tuned implementation. Based on these results, CSR-k appears to be a promising multilevel formulation of CSR for adapting sparse computations to multico- e processors with NUMA memory hierarchies.\",\n \"Title: Locality-Aware Laplacian Mesh Smoothing\\nYear: 2016\\n\\nAbstract: In this paper, we propose a novel reordering scheme to improve the performance of a Laplacian Mesh Smoothing (LMS). While the Laplacian smoothing algorithm is well optimized and studied, we show how a simple reordering of the vertices of the mesh can greatly improve the execution time of the smoothing algorithm. The idea of our reordering is based on (i) the postulate that cache misses are a very time consuming part of the execution of LMS, and (ii) the study of the reuse distance patterns of various executions of the LMS algorithm. Our reordering algorithm is very simple but allows for huge performance improvement. We ran it on a Westmere-EX platform and obtained a speedup of 75 on 32 cores compared to the single core execution without reordering, and a gain in execution of 32% on 32 cores compared to state of the art reordering. Finally, we show that we leave little room for a better ordering by reducing the L2 and L3 cache misses to a bare minimum.\",\n \"Title: Research and Education in Computational Science and Engineering.\\nYear: 2018\\n\\nAbstract: This report presents challenges, opportunities, and directions for computational science and engineering (CSE) research and education for the next decade. Over the past two decades the field of CSE has penetrated both basic and applied research in academia, industry, and laboratories to advance discovery, optimize systems, support decision-makers, and educate the scientific and engineering workforce. Informed by centuries of theory and experiment, CSE performs computational experiments to answer questions that neither theory nor experiment, alone is equipped to answer. CSE provides scientists and engineers with algorithmic inventions and software systems that, transcend disciplines and scales. CSE brings the power of parallelism to bear on troves of data. Mathematics-based advanced computing has become a prevalent means of discovery and innovation in essentially all areas of science, engineering, technology, and society, and the CSE community is at the core of this transformation. However, a combination of disruptive developments-including the architectural complexity of extreme-scale computing, the data revolution and increased attention to data-driven discovery, and the specialization required to follow the applications to new frontiers-is redefining the scope and reach of the CSE endeavor. With these many current and expanding opportunities for the CSE field, there is a growing demand for CSE graduates and a need to expand CSE educational offerings. This need includes CSE programs at both the undergraduate and graduate levels, as well as continuing education and professional development programs, exploiting the synergy between computational science and data science. Yet, as institutions consider new and evolving educational programs, it is essential to consider the broader research challenges and opportunities that provide the context for CSE education and workforce development.\",\n \"Title: Identifying the Right Replication Level to Detect and Correct Silent Errors at Scale\\nYear: 2017\\n\\nAbstract: This paper provides a model and an analytical study of replication as a technique to detect and correct silent errors. Although other detection techniques exist for HPC applications, based on algorithms (ABFT), invariant preservation or data analytics, replication remains the most transparent and least intrusive technique. We explore the right level (duplication, triplication or more) of replication needed to efficiently detect and correct silent errors. Replication is combined with checkpointing and comes with two flavors: process replication and group replication. Process replication applies to message-passing applications with communicating processes. Each process is replicated, and the platform is composed of process pairs, or triplets. Group replication applies to black-box applications, whose parallel execution is replicated several times. The platform is partitioned into two halves (or three thirds). In both scenarios, results are compared before each checkpoint, which is taken only when both results (duplication) or two out of three results (triplication) coincide. If not, one or more silent errors have been detected, and the application rolls back to the last checkpoint. We provide a detailed analytical study of both scenarios, with formulas to decide, for each scenario, the optimal parameters as a function of the error rate, checkpoint cost, and platform size. We also report a set of extensive simulation results that corroborates the analytical model.\",\n \"Title: Co-scheduling Amdahl applications on cache-partitioned systems\\nYear: 2018\\n\\nAbstract: AbstractCache-partitioned architectures allow subsections of the shared last-level cache LLC to be exclusively reserved for some applications. This technique dramatically limits interactions between applications that are concurrently executing on a multicore machine. Consider n applications that execute concurrently, with the objective to minimize the makespan, defined as the maximum completion time of the n applications. Key scheduling questions are as follows: i which proportion of cache and ii how many processors should be given to each application? In this article, we provide answers to i and ii for Amdahl applications. Even though the problem is shown to be NP-complete, we give key elements to determine the subset of applications that should share the LLC while remaining ones only use their smaller private cache. Building upon these results, we design efficient heuristics for Amdahl applications. Extensive simulations demonstrate the usefulness of co-scheduling when our efficient cache partitioning strategies are deployed.\",\n \"Title: Realizing the potential of data science.\\nYear: 2018\\n\\nAbstract: Data science promises new insights, helping transform information into knowledge that can drive science and industry.\",\n \"Title: Scheduling Parallel Tasks under Multiple Resources: List Scheduling vs. Pack Scheduling\\nYear: 2018\\n\\nAbstract: Scheduling in High-Performance Computing (HPC) has been traditionally centered around computing resources (e.g., processors/cores). The ever-growing amount of data produced by modern scientific applications start to drive novel architectures and new computing frameworks to support more efficient data processing, transfer and storage for future HPC systems. This trend towards data-driven computing demands the scheduling solutions to also consider other resources (e.g., I/O, memory, cache) that can be shared amongst competing applications. In this paper, we study the problem of scheduling HPC applications while exploring the availability of multiple types of resources that could impact their performance. The goal is to minimize the overall execution time, or makespan, for a set of moldable tasks under multiple-resource constraints. Two scheduling paradigms, namely, list scheduling and pack scheduling, are compared through both theoretical analyses and experimental evaluations. Theoretically, we prove, for several algorithms falling in the two scheduling paradigms, tight approximation ratios that increase linearly with the number of resource types. As the complexity of direct solutions grows exponentially with the number of resource types, we also design a strategy to indirectly solve the problem via a transformation to a single-resource-type problem, which can significantly reduce the algorithms' running times without compromising their approximation ratios. Experiments conducted on Intel Knights Landing with two resource types (processor cores and high-bandwidth memory) and simulations designed on more resource types confirm the benefit of the transformation strategy and show that pack-based scheduling, despite having a worse theoretical bound, offers a practically promising and easy-to-implement solution, especially when more resource types need to be managed.\",\n \"Title: Coping with silent and fail-stop errors at scale by combining replication and checkpointing.\\nYear: 2018\\n\\nAbstract: This paper provides a model and an analytical study of replication as a technique to cope with silent errors, as well as a mixture of both silent and fail-stop errors on large-scale platforms. Compared with fail-stop errors that are immediately detected when they occur, silent errors require a detection mechanism. To detect silent errors, many application-specific techniques are available, either based on algorithms (e.g., ABFT), invariant preservation or data analytics, but replication remains the most transparent and least intrusive technique. We explore the right level (duplication, triplication or more) of replication for two frameworks: (i) when the platform is subject to only silent errors, and (ii) when the platform is subject to both silent and fail-stop errors. A higher level of replication is more expensive in terms of resource usage but enables to tolerate more errors and to even correct some errors, hence there is a trade-off to be found. Replication is combined with checkpointing and comes with two flavors: process replication and group replication. Process replication applies to message-passing applications with communicating processes. Each process is replicated, and the platform is composed of process pairs, or triplets. Group replication applies to black-box applications, whose parallel execution is replicated several times. The platform is partitioned into two halves (or three thirds). In both scenarios, results are compared before each checkpoint, which is taken only when both results (duplication) or two out of three results (triplication) coincide. Otherwise, one or more silent errors have been detected, and the application rolls back to the last checkpoint, as well as when fail-stop errors have struck. We provide a detailed analytical study for all of these scenarios, with formulas to decide, for each scenario, the optimal parameters as a function of the error rate, checkpoint cost, and platform size. We also report a set of extensive simulation results that nicely corroborates the analytical model.\",\n \"Title: A Scalability and Sensitivity Study of Parallel Geometric Algorithms for Graph Partitioning\\nYear: 2018\\n\\nAbstract: Graph partitioning arises in many computational simulation workloads, including those that involve finite difference or finite element methods, where partitioning enables efficient parallel processing of the entire simulation. We focus on parallel geometric algorithms for partitioning large graphs whose vertices are associated with coordinates in two or three-dimensional space on multi-core processors. Compared with other types of partitioning algorithms, geometric schemes generally show better scalability on a large number of processors or cores. This paper studies the scalability and sensitivity of two parallel algorithms, namely, recursive coordinate bisection (denoted by pRCB) and geometric mesh partitioning (denoted by pGMP), in terms of their robustness to several key factors that affect the partition quality, including coordinate perturbation, approximate embedding, mesh quality and graph planarity. Our results indicate that the quality of a partition as measured by the size of the edge separator (or cutsize) remains consistently better for pGMP compared to pRCB. On average for our test suite, relative to pRCB, pGMP yields 25% smaller cutsizes on the original embedding, and across all perturbations cutsizes that are smaller by at least 8% and by as much as 50%. Not surprisingly, higher quality cuts are obtained at the expense of longer execution times; on a single core, pGMP has an average execution time that is almost 10 times slower than that of pRCB, but it scales better and catches up at 32-cores to be slower by less than 20%. With the current trends in core counts that continue to increase per chip, these results suggest that pGMP presents an attractive solution if a modest number of cores can be deployed to reduce execution times while providing high quality partitions.\",\n \"Title: Reservation Strategies for Stochastic Jobs\\nYear: 2019\\n\\nAbstract: In this paper, we are interested in scheduling stochastic jobs on a reservation-based platform. Specifically, we consider jobs whose execution time follows a known probability distribution. The platform is reservation-based, meaning that the user has to request fixed-length time slots. The cost then depends on both (i) the request duration (pay for what you ask); and (ii) the actual execution time of the job (pay for what you use). A reservation strategy determines a sequence of increasing length reservations, which are paid for until one of them allows the job to successfully complete. The goal is to minimize the total expected cost of the strategy. We provide some properties of the optimal solution, which we characterize up to the length of the first reservation. We then design several heuristics based on various approaches, including a brute-force search of the first reservation length while relying on the characterization of the optimal strategy, as well as the discretization of the target continuous probability distribution together with an optimal dynamic programming algorithm for the discrete distribution. We evaluate these heuristics using two different platform models and cost functions: The first one targets a cloud oriented platform (e.g., Amazon AWS) using jobs that follow a large number of usual probability distributions (e.g., Uniform, Exponential, LogNormal, Weibull, Beta), and the second one is based on interpolating traces from a real neuroscience application executed on an HPC platform. An extensive set of simulation results show the effectiveness of the proposed reservation-based approaches for scheduling stochastic jobs.\",\n \"Title: On-the-fly scheduling versus reservation-based scheduling for unpredictable workflows\\nYear: 2019\\n\\nAbstract: AbstractScientific insights in the coming decade will clearly depend on the effective processing of large data sets generated by dynamic heterogeneous applications typical of workflows in large data centers or of emerging fields like neuroscience. In this article, we show how these big data workflows have a unique set of characteristics that pose challenges for leveraging HPC methodologies, particularly in scheduling. Our findings indicate that execution times for these workflows are highly unpredictable and are not correlated with the size of the data set involved or the precise functions used in the analysis. We characterize this inherent variability and sketch the need for new scheduling approaches by quantifying significant gaps in achievable performance. Through simulations, we show how on-the-fly scheduling approaches can deliver benefits in both system-level and user-level performance measures. On average, we find improvements of up to 35% in system utilization and up to 45% in average stretch of the applications, illustrating the potential of increasing performance through new scheduling approaches.\",\n \"Title: Speculative Scheduling for Stochastic HPC Applications\\nYear: 2019\\n\\nAbstract: New emerging fields are developing a growing number of large-scale applications with heterogeneous, dynamic and data-intensive requirements that put a high emphasis on productivity and thus are not tuned to run efficiently on today's high performance computing (HPC) systems. Some of these applications, such as neuroscience workloads and those that use adaptive numerical algorithms, develop modeling and simulation workflows with stochastic execution times and unpredictable resource requirements. When they are deployed on current HPC systems using existing resource management solutions, it can result in loss of efficiency for the users and decrease in effective system utilization for the platform providers.\\n\\nIn this paper, we consider the current HPC scheduling model and describe the challenge it poses for stochastic applications due to the strict requirement in its job deployment policies. To address the challenge, we present speculative scheduling techniques that adapt the resource requirements of a stochastic application on-the-fly, based on its past execution behavior instead of relying on estimates given by the user. We focus on improving the overall system utilization and application response time without disrupting the current HPC scheduling model or the application development process. Our solution can operate alongside existing HPC batch schedulers without interfering with their usage modes. We show that speculative scheduling can improve the system utilization and average application response time by 25-30% compared to the classical HPC approach.\",\n \"Title: Multi-Resource List Scheduling of Moldable Parallel Jobs under Precedence Constraints.\\nYear: 2021\\n\\nAbstract: The scheduling literature has traditionally focused on a single type of resource (e.g., computing nodes). However, scientific applications in modern High-Performance Computing (HPC) systems process large amounts of data, hence have diverse requirements on different types of resources (e.g., cores, cache, memory, I/O). All of these resources could potentially be exploited by the runtime scheduler to improve the application performance. In this paper, we study multi-resource scheduling to minimize the makespan of computational workflows comprised of parallel jobs subject to precedence constraints. The jobs are assumed to be moldable, allowing the scheduler to flexibly select a variable set of resources before execution. We propose a multi-resource, list-based scheduling algorithm, and prove that, on a system with $d$ types of schedulable resources, our algorithm achieves an approximation ratio of $1.619d+2.545\\\\sqrt{d}+1$ for any $d$, and a ratio of $d+O(\\\\sqrt[3]{d^2})$ for large $d$. We also present improved results for independent jobs and for jobs with special precedence constraints (e.g., series-parallel graphs and trees). Finally, we prove a lower bound of $d$ on the approximation ratio of any list scheduling scheme with local priority considerations. To the best of our knowledge, these are the first approximation results for moldable workflows with multiple resource requirements.\",\n \"Title: Resilient Scheduling of Moldable Parallel Jobs to Cope With Silent Errors\\nYear: 2022\\n\\nAbstract: We study the resilient scheduling of moldable parallel jobs on high-performance computing (HPC) platforms. Moldable jobs allow for choosing a processor allocation before execution, and their execution time obeys various speedup models. The objective is to minimize the overall completion time or the makespan, when jobs can fail due to silent errors and hence may need to be re-executed after each failure until successful completion. Our work generalizes the classical scheduling framework for failure-free jobs. To cope with silent errors, we introduce two resilient scheduling algorithms, \\n<sc xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">Lpa-List</small>\\n and \\n<sc xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">Batch-List</small>\\n, both of which use the \\n<sc xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">List</small>\\n strategy to schedule the jobs. Without knowing a priori how many times each job will fail, \\n<sc xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">Lpa-List</small>\\n relies on a local strategy to allocate processors to the jobs, while \\n<sc xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">Batch-List</small>\\n schedules the jobs in batches and allows only a restricted number of failures per job in each batch. We prove approximation ratios for the two algorithms under several prominent speedup models (e.g., roofline, communication, Amdahl, power, monotonic, and a mix model). An extensive set of simulations is conducted to evaluate different variants of the two algorithms, and the results show that they consistently outperform some baseline heuristics. Overall, our best algorithm is within a factor of 1.6 of a lower bound on average over the entire set of experiments, and within a factor of 4.2 in the worst case.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":73,"string":"73"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":61,"string":"61"}}},{"rowIdx":62,"cells":{"question_id":{"kind":"string","value":"Yifan Xu"},"question":{"kind":"string","value":"Generate an abstract for the title \"A rank-one fitting algorithm for unconstrained optimization problems\" using the following items: 1. Rank-one algorithm\n2. Modified fitting\n3. Quadratic function\n4. Global convergence\n5. Linear convergence"},"answer":{"kind":"string","value":"This paper proposes a rank-one modified fitting algorithm. The main feature of the approach is that the update formula for the deflection matrix in an iteration is deduced from a quadratic fitting function, not from the traditional quasi-Newton equation. Under some mild assumptions, the algorithm is globally and linearly convergent."},"correct_answer":{"kind":"string","value":"This paper proposes a rank-one modified fitting algorithm. The main feature of the approach is that the update formula for the deflection matrix in an iteration is deduced from a quadratic fitting function, not from the traditional quasi-Newton equation. Under some mild assumptions, the algorithm is globally and linearly convergent."},"documents":{"kind":"list like","value":["Title: The Algorithm of Sequential KKT Equations by Nonmonotone Search for Arbitrary Initial Point\nYear: 2001\n\nAbstract: In this paper, a new algorithm for arbitrary initial point is proposed. The feature of the algorithm is that only KKT equations are solved in each iteration which greatly decreases the amount of computation. Under some proper assumptions, the algorithm is globally and superlinearly convergent.","Title: A nonlinear Lagrangian dual for integer programming\nYear: 2002\n\nAbstract: Nonlinear Lagrangian theory offers a success guarantee for the dual search via construction of a nonlinear support of the perturbation function at the optimal point. In this paper, a new nonlinear dual formulation of an exponential form is proposed for bounded integer programming. This new formulation possesses an asymptotic strong duality property and guarantees a success in identifying a primal optimum solution. No actual dual search is needed in the solution process when the parameter of the nonlinear Lagrangian formulation is set to be large enough.","Title: Generalized Nonlinear Lagrangian Formulation for Bounded Integer Programming\nYear: 2005\n\nAbstract: Several nonlinear Lagrangian formulations have been recently proposed forbounded integer programming problems. While possessing an asymptotic strong dualityproperty, these formulations offer a success guarantee for the identification of an optimalprimal solution via a dual search. Investigating common features of nonlinear Lagrangianformulations in constructing a nonlinear support for nonconvex piecewise constant perturbation function, this paper proposes a generalized nonlinear Lagrangian formulation of which many existing nonlinear Lagrangian formulations become special cases.","Title: Asymptotic strong determination in integer programming: Quasi dual method\nYear: 2003\n\nAbstract: . Although the Lagrangian method is a powerful dual search method in integer programming, it often fail to identify the optimal\n solution of the primal problem. In this paper, a quasi dual formulation is proposed for bounded integer programming. This\n formulation possesses an asymptotic strong determination property and guarantees a success for identifying an optimum solution.\n Its another feature is that no actual dual search is needed when the parameters of the method are set to be large enough.","Title: Contamination control in food supply chain\nYear: 2010\n\nAbstract: In this paper, we study a contamination control problem in food supply chain. We formulate the problem as a dynamic programming problem and then study the structure of the optimal control which turns out to be very similar to the hedging-point type of policy. Under the environment in which there is uncertainty associated with contamination control, we propose a stochastic dynamic programming formulation with chance constraints, to which simulation based methods could be applied.","Title: On the tour planning problem.\nYear: 2012\n\nAbstract: Increasingly, tourists are planning trips by themselves using the vast amount of information available on the Web. However, they still expect and want trip plan advisory services. In this paper, we study the tour planning problem in which our goal is to design a tour trip with the most desirable sites, subject to various budget and time constraints. We first establish a framework for this problem, and then formulate it as a mixed integer linear programming problem. However, except when the size of the problem is small, say, with less than 20-30 sites, it is computationally infeasible to solve the mixed-integer linear programming problem. Therefore, we propose a heuristic method based on local search ideas. The method is efficient and provides good approximation solutions. Numerical results are provided to validate the method. We also apply our method to the team orienteering problem, a special case of the tour planning problem which has been considered in the literature, and compare our method with other existing methods. Our numerical results show that our method produces very good approximation solutions with relatively small computational efforts comparing with other existing methods. © 2010 Springer Science+Business Media, LLC.","Title: A mixed and superlinearly convergent algorithm for constrained optimization\nYear: 2003\n\nAbstract: In this paper, a mixed QP-free method for constrained optimization problem is proposed. This new method consists of two different sub-methods, sub-method I and sub-method II. These two sub-methods are all QP-free. A switch is designed to decide which sub-method should be adopted in each iteration. Under some mild assumptions, we prove that the method is globally and superlinearly convergent.","Title: Simple transformation functions for finding better minima\nYear: 2008\n\nAbstract: This work presents two transformation functions, the α-function and the M-function, for finding better minimizers in global optimization. We prove that under some general assumptions these functions possess the characters of both tunnelling functions and filled functions. Numerical tests from some test functions show that our transformation functions are very effective in finding better minima.","Title: Stochastic control via direct comparison\nYear: 2011\n\nAbstract: The standard approach to stochastic control is dynamic programming. In this paper, we introduce an alternative approach based on direct comparison of the performance of any two policies. This is achieved by modeling the state process as a continuous-time and continuous-state Markov process and applying the same ideas as for the discrete-time and discrete-state case. This approach is simple and intuitively clear; it applies to different problems with, finite and infinite horizons, discounted and long-run-average performance, continuous and jump diffusions, in the same way. Discounting is not needed when dealing with long-run average performance. The approach provides a unified framework for stochastic control and other optimization theory and methodologies, including Markov decision processes, perturbation analysis, and reinforcement learning.","Title: Implicit Multifunction Theorems in Banach Spaces.\nYear: 2014\n\nAbstract: This paper is mainly devoted to the study of implicit multifunction theorems in terms of Clarke coderivative in general Banach spaces. We present new sufficient conditions for the local metric regularity, metric regularity, Lipschitz-like property, nonemptiness, and lower semicontinuity of implicit multifunctions in general Banach spaces. The basic tools of our analysis involve the Ekeland variational principle, the Clarke subdifferential, and the Clarke coderivative.","Title: Dynamic inventory and pricing policy in a capacitated stochastic inventory system with fixed ordering cost.\nYear: 2012\n\nAbstract: We study a dynamic inventory and pricing optimization problem in a periodic review inventory system with setup cost and finite ordering capacity in each period. We show that the optimal inventory control is characterized by an (s,s′,p) policy in four regions of the starting inventory level.","Title: Openness results for parametric set-valued mappings in Asplund spaces.\nYear: 2014\n\nAbstract: In this paper, we first prove a lemma about the lower semicontinuity of the distance function in infinite dimensional spaces, which is crucial to openness results hereafter. Then we obtain some openness results in terms of Frechet coderivatives for parametric set-valued mappings in Asplund spaces under mild conditions. The results of the paper generalize several corresponding results in the recent literature. Finally, we give two examples to illustrate our openness results.","Title: Non-cooperative Resource Allocation Scheme for Data Access in VANET Cloud Environment\nYear: 2015\n\nAbstract: Data dissemination, especially large amount of data transmission, has become one of the main tasks for the selfish vehicle nodes in Vehicular Ad hoc Networks (VANETs). Exploiting the Road Side Unites (RSUs), which construct the Cloud Computing environment, provides more data access opportunities and stable communication time for the vehicles. However, due to the high mobility of the vehicles and the frequent changes in the network topology, the flow rate of the vehicles for multimedia data access may fluctuate, leading to the high transmission latency. In this paper, the cloud resource allocation for data access is investigated with the non-cooperative cloud resource allocation game based on Gauss-Seidel iteration method. Specifically, an on-demand precision control strategy is proposed to achieve the iteration precision of the flow control. The analysis based on these models lays a theoretical method foundation on the noncooperative game computing process. Furthermore, two common methods for calculating the Nash Equilibrium Point (NEP) of the cloud resource allocation game are compared based on the analytical results. The validity of the modeling and the accuracy of the analysis are verified through the extensive simulations, which also guide the design of more sophisticated cloud resource allocation schemes.","Title: A Nanoporous Alumina Membrane Based Electrochemical Biosensor for Histamine Determination with Biofunctionalized Magnetic Nanoparticles Concentration and Signal Amplification.\nYear: 2016\n\nAbstract: Histamine is an indicator of food quality and indispensable in the efficient functioning of various physiological systems. Rapid and sensitive determination of histamine is urgently needed in food analysis and clinical diagnostics. Traditional histamine detection methods require qualified personnel, need complex operation processes, and are time-consuming. In this study, a biofunctionalized nanoporous alumina membrane based electrochemical biosensor with magnetic nanoparticles (MNPs) concentration and signal amplification was developed for histamine determination. Nanoporous alumina membranes were modified by anti-histamine antibody and integrated into polydimethylsiloxane (PDMS) chambers. The specific antibody modified MNPs were used to concentrate histamine from samples and transferred to the antibody modified nanoporous membrane. The MNPs conjugated to histamine were captured in the nanopores via specific reaction between histamine and anti-histamine antibody, resulting in a blocking effect that was amplified by MNPs in the nanopores. The blockage signals could be measured by electrochemical impedance spectroscopy across the nanoporous alumina membrane. The sensing platform had great sensitivity and the limit of detection (LOD) reached as low as 3 nM. This biosensor could be successfully applied for histamine determination in saury that was stored in frozen conditions for different hours, presenting a potentially novel, sensitive, and specific sensing system for food quality assessment and safety support.","Title: An Alarm Flood Pattern Matching Algorithm Based On Modified Blast With Leveshtein Distance\nYear: 2016\n\nAbstract: Alarm flooding is one of the main problems in alarm management. Alarm flood pattern analysis is helpful for root cause analysis of historical floods and for incoming flood prediction. This paper introduces a data driven method for alarm flood pattern matching. A modified BLAST algorithm with Levenshtein distance is proposed to discover similar alarm floods. A quadruple tank process is simulated to test the effectiveness of the proposed algorithm. The results show that the algorithm is quick and accurate.","Title: A resource allocation game with restriction mechanism in VANET cloud.\nYear: 2017\n\nAbstract: In Vehicular Ad hoc Networks (VANETs), because of the selfishness of the vehicles, the resource allocation in VANET has become one of the primary tasks. Exploiting the Road Side Units (RSUs), which constructs the Cloud Computing environment, provides more data access opportunities and stable communication time for the vehicles. We investigated the cloud resource allocation for data access with noncooperative game based on a Gauss-Seidel iteration method. We further proposed a repeated game scheme, which can approximately achieve the near Pareto-optimal flow allocation among the vehicles. Considering the vehicles' irrational behavior, a punishment strategy was designed to prevent the vehicles from behavior deviation. The analysis based on these models lays a theoretical method foundation on cloud resource allocation process. The validity of the modeling and the accuracy of the analysis were verified through the extensive simulations, which also guide the future design of more sophisticated cloud resource allocation schemes. Copyright (C) 2016 John Wiley & Sons, Ltd.","Title: Data Gathering Framework Based On Fog Computing Paradigm In Vanets\nYear: 2017\n\nAbstract: Vehicular nodes are equipped with more and more sensing units, and large amount of sensing data are generated. This makes the data gathering and monitoring is a challenging problem in VANETs. In this paper we first present an sensing and data gathering framework through the concept of fog computing in VANETs, then we propose an event-based data gathering scheme based on this framework that adaptively adjusts the threshold to upload suitable amount of data for decision making, while at the same time suppress unnecessary message transmissions. Preliminary experiments demonstrate the effectiveness of the proposed algorithm in vehicular sensing applications.","Title: Location-Aware Worker Selection for Mobile Opportunistic Crowdsensing in VANETs.\nYear: 2017\n\nAbstract: Worker selection for location-based crowdsensing can be described as the strategy of choosing the proper cooperative participants to complete the allocated tasks in specified regions. Due to the mobility pattern of vehicles and regular road networks, the Vehicular Ad-hoc Networks (VANETs) are expected to provide many opportunities for task execution in opportunistic crowdsensing, enabling some emerging applications. To fulfill tasks with the least execution time under the spatial-temporal restrictions, we propose a Location-Aware Worker Selection scheme (LAWS) for mobile opportunistic crowdsensing in urban areas. Different from the traditional worker selection schemes assigning a task to one designated worker, LAWS exploits the vehicles contacts provided by taxicabs and buses and makes full advantage of prior knowledge of vehicles to promote the performance of task execution. Real-world vehicle traces are introduced to construct the extensive simulations. The simulation results show that our scheme outperforms the well-known algorithms, e.g., Epidemic, Prophet, in terms of the task execution success ratio, the execution time and the network load.","Title: Efficient parallel determinacy race detection for two-dimensional dags.\nYear: 2018\n\nAbstract: A program is said to have a determinacy race if logically parallel parts of a program access the same memory location and one of the accesses is a write. These races are generally bugs in the program since they lead to non-deterministic program behavior --- different schedules of the program can lead to different results. Most prior work on detecting these races focuses on a subclass of programs with fork-join parallelism.\n\nThis paper presents a race-detection algorithm, 2D-Order, for detecting races in a more general class of programs, namely programs whose dependence structure can be represented as planar dags embedded in 2D grids. Such dependence structures arise from programs that use pipelined parallelism or dynamic programming recurrences. Given a computation with T1 work and T∞ span, 2D-Order executes it while also detecting races in O(T1/P + T∞) time on P processors, which is asymptotically optimal.\n\nWe also implemented PRacer, a race-detection algorithm based on 2D-Order for Cilk-P, which is a language for expressing pipeline parallelism. Empirical results demonstrate that PRacer incurs reasonable overhead and exhibits scalability similar to the baseline (executions without race detection) when running on multiple cores.","Title: Improved Benders Decomposition For Capacitated Hub Location Problem With Incomplete Hub Networks\nYear: 2017\n\nAbstract: The hub location problem (HLP) has been studied by researchers for many years. A number of model variants and solution techniques for solving the problem have been proposed. Most researchers consider the uncapacitated HLP(UHLP), given the difficulty in computation that comes with capacity constraints. Particularly, together with incomplete hub networks, capacity constraints have shown to be highly intractable. We develop a novel, efficient Benders decomposition algorithm to solve the CHLP with incomplete hub networks. In order to explore the impact of capacity constraints on hubs and backbone arcs, the CAB dataset is used as a case study. In addition, we compare the performance of our improved algorithm to the classical one. We find that capacity constraints on hubs and backbone links tend to render a robust network with more fully connected hub node pairs and flexible linking structure. In addition, the computation time is significantly reduced, up to one order of magnitude, compared with the state-of-the-art. We believe that our work lays the foundation for solving more realistic hub location problems.","Title: Fog-Based Two-Phase Event Monitoring and Data Gathering in Vehicular Sensor Networks.\nYear: 2018\n\nAbstract: Vehicular nodes are equipped with more and more sensing units, and a large amount of sensing data is generated. Recently, more and more research considers cooperative urban sensing as the heart of intelligent and green city traffic management. The key components of the platform will be a combination of a pervasive vehicular sensing system, as well as a central control and analysis system, where data-gathering is a fundamental component. However, the data-gathering and monitoring are also challenging issues in vehicular sensor networks because of the large amount of data and the dynamic nature of the network. In this paper, we propose an efficient continuous event-monitoring and data-gathering framework based on fog nodes in vehicular sensor networks. A fog-based two-level threshold strategy is adopted to suppress unnecessary data upload and transmissions. In the monitoring phase, nodes sense the environment in low cost sensing mode and generate sensed data. When the probability of the event is high and exceeds some threshold, nodes transfer to the event-checking phase, and some nodes would be selected to transfer to the deep sensing mode to generate more accurate data of the environment. Furthermore, it adaptively adjusts the threshold to upload a suitable amount of data for decision making, while at the same time suppressing unnecessary message transmissions. Simulation results showed that the proposed scheme could reduce more than 84 percent of the data transmissions compared with other existing algorithms, while it detects the events and gathers the event data.","Title: Anti-jamming transmission in UAV communication networks: A Stackelberg game approach.\nYear: 2017\n\nAbstract: We investigate the anti-jamming problem in unmanned aerial vehicles (UAV) communication networks, in which the mutual interference among UAVs is considered. A Stackelberg game approach is proposed to solve this problem. The smart jammer who has the privilege over multiple users acts first as the leader of the game, while the users act as the followers after knowing the strategy of the smart jammer. The optimal transmission power of users and smart jammer are derived, and the influence of transmission cost on the users and the smart jammer are shown in the simulation results. The existence as well as the uniqueness of the Stackelberg equlibrium (SE) have been proved as well.","Title: A One-Leader Multi-Follower Bayesian-Stackelberg Game for Anti-Jamming Transmission in UAV Communication Networks.\nYear: 2018\n\nAbstract: This paper focuses on the anti-jamming transmission problem in unmanned aerial vehicle (UAV) communication networks. Considering the incomplete information constraint and the co-channel mutual interference, a Bayesian Stackelberg game is proposed to formulate the competitive relations between UAVs (users) and the jammer. Specifically, the jammer acts as the leader, whereas users act as followers of the proposed game. Based on their utility functions, the jammer and users select their optimal power control strategies respectively. In addition, the observation error is also investigated in this paper. Due to the incomplete information constraint and the existence of co-channel mutual interference, it is challenging to obtain Stackelberg equilibrium (SE) of the proposed game. Thus, a sub-gradient based Bayesian Stackelberg iterative algorithm is proposed to obtain SE. Finally, simulations are conducted to demonstrate the performance of the proposed algorithm, and the impact of incomplete information and observation error on users' utilities are also presented.","Title: A NUMA-Aware Provably-Efficient Task-Parallel Platform Based on the Work-First Principle\nYear: 2018\n\nAbstract: Task parallelism is designed to simplify the task of parallel programming. When executing a task parallel program on modern NUMA architectures, it can fail to scale due to the phenomenon called work inflation, where the overall processing time that multiple cores spend on doing useful work is higher compared to the time required to do the same amount of work on one core, due to effects experienced only during parallel executions such as additional cache misses, remote memory accesses, and memory bandwidth issues.One can mitigate work inflation by co-locating the computation with its data, but this is nontrivial to do with task parallel programs. First, by design, the scheduling for task parallel programs is automated, giving the user little control over where the computation is performed. Second, the platforms tend to employ work stealing, which provides strong theoretical guarantees, but its randomized protocol for load balancing does not discern between work items that are far away versus ones that are closer.In this work, we propose NUMA-WS, a NUMA-aware task parallel platform engineered based on the work-first principle. By abiding by the work-first principle, we are able to obtain a platform that is work efficient, provides the same theoretical guarantees as a classic work stealing scheduler, and mitigates work inflation. We have extended Cilk Plus runtime system to implemented NUMA-WS. Empirical results indicate that the NUMA-WS is work efficient and can provide better scalability by mitigating work inflation.","Title: Power Attack and Protected Implementation on Lightweight Block Cipher SKINNY\nYear: 2018\n\nAbstract: SKINNY is a new lightweight tweakable block cipher family, which can compete to other lightweight cipher in terms of hardware or software implementations. While its theoretical security has been widely studied, little effort has been made to analyze its implementation security such as side-channel attacks protection. In this paper, we first give correlation power attack and its experiment on SKINNY. Then, a masking scheme for software SKINNY is proposed against side-channel attacks. Its implementation shows that the protected SKINNY only costs 8.42%, 183.27%, and 90.85% of extra code, time, and RAM, respectively.","Title: Collaborative Route Plan For Parking Sites Selection In Bike-Sharing Systems\nYear: 2018\n\nAbstract: In order to alleviate the traffic congestion caused by the bike-sharing system, the bicycles should be parked in designated parking sites, particularly around the hot scenic spots. A proper route, which guides the cyclers to select a vacant place among the sites to park the bike, is required. In this paper, the Expected Travel Distance (KID) and the Probability of Successful Parking (PSP) are formulated to evaluate the routes, which will guide the users to travel all the parking sites. We exploit the Poisson process to model the increment of the bicycle number in the parking site and construct the travel tree for the route plan problem. To provide a proper route, we propose the GOR algorithm and the F-M method based on the travel tree. Through extensive simulations, our algorithms are compared with TSP in terms of ETD, PSP and the execution time.","Title: Plasmonic Sensing Characteristics of Gold Nanorods with Large Aspect Ratios.\nYear: 2018\n\nAbstract: Plasmonic gold nanorods play important roles in nowadays state-of-the-art plasmonic sensing techniques. Most of the previous studies and applications focused on gold nanorods with relatively small aspect ratios, where the plasmon wavelengths are smaller than 900 nm. Gold nanorods with large aspect ratios are predicted to exhibit high refractive-index sensitivity (Langmir 2008, 24, 5233-5237), which therefore should be promising for the development of high-performance plasmonic chemical- and bio-sensors. In this study, we developed gold nanorods with aspect ratios over 7.9, which exhibit plasmon resonances around 1064 nm. The refractive index (RI) sensitivity of these nanorods have been evaluated by varying their dielectric environment, whereby a sensitivity as high as 473 nm/RIU (refractive index unit) can be obtained. Furthermore, we have demonstrated the large-aspect-ratio nanorods as efficient substrate for surface enhanced Raman spectroscopy (SERS), where an enhancement factor (EF) as high as 9.47 x 10(8) was measured using 4-methylbenzenethiol (4-MBT) as probe molecule. Finally, a type of flexible SERS substrate is developed by conjugating the gold nanorods with the polystyrene (PS) polymer. The results obtained in our study can benefit the development of plasmonic sensing techniques utilized in the near-infrared spectral region.","Title: A stochastic multi-channel revenue management model with time-dependent demand.\nYear: 2018\n\nAbstract: •This paper examines the firm's optimal channel control strategy with combining its revenue management decision.•A multi-period multi-channel continuous-time model with time-dependent arrival rates has been proposed.•Using the Maximum Principle, the optimal channel control rules are found and a threshold channel control policy is proposed.","Title: Proactive work stealing for futures.\nYear: 2019\n\nAbstract: The use of futures provides a flexible way to express parallelism and can generate arbitrary dependences among parallel subcomputations. The additional flexibility that futures provide comes with a cost, however. When scheduled using classic work stealing, a program with futures, compared to a program that uses only fork-join parallelism, can incur a much higher number of \"deviations,\" a metric for evaluating the performance of parallel executions. All prior works assume a parsimonious work-stealing scheduler, however, where a worker thread (surrogate of a processor) steals work only when its local deque becomes empty.\n\nIn this work, we investigate an alternative scheduling approach, called ProWS, where the workers perform proactive work stealing when handling future operations. We show that ProWS, for programs that use futures, can provide provably efficient execution time and equal or better bounds on the number of deviations compared to classic parsimonious work stealing. Given a computation with T1 work and T∞ span, ProWS executes the computation on P processors in expected time O(T1/P + T∞ lg P), with an additional lg P overhead on the span term compared to the parsimonious variant. For structured use of futures, where each future is single touch with no race on the future handle, the algorithm incurs deviations, matching that of the parsimonious variant. For general use of futures, the algorithm incurs O(mkT∞ + PT∞ lg P) deviations, where mk is the maximum number of future touches that are logically parallel. Compared to the bound for the parsimonious variant, O(kT∞ + PT∞), with k being the total number of touches in the entire computation, this bound is better assuming mk = Ω(P lg P) and is smaller than k, which holds true for all the benchmarks we examined.","Title: Inventory centralization with risk-averse newsvendors.\nYear: 2018\n\nAbstract: In the paper, we study the inventory centralization problem with risk-averse newsvendors using cooperative game theory. Pareto-optimality and collective rationality conditions are adopted to characterize the stable profit allocations among coalition members. Pareto-optimal profit allocation rules are derived for exponential and power utilities while the necessary and sufficient conditions are shown for stable profit allocations. We also show that the game model has a nonempty core when the exponential and power utilities are adopted to describe the risk-averse behavior.","Title: Deep Review Sharing\nYear: 2019\n\nAbstract: Review-Based Software Improvement (RBSI for short) has drawn increasing research attentions in recent years. Relevant efforts focus on how to leverage the underlying information within reviews to obtain a better guidance for further updating. However, few efforts consider the Projects Without sufficient Reviews (PWR for short). Actually, PWR dominates the software projects, and the lack of PWR-based RBSI research severely blocks the improvement of certain software. In this paper, we make the first attempt to pave the road. Our goal is to establish a generic framework for sharing suitable and informative reviews to arbitrary PWR. To achieve this goal, we exploit techniques of code clone detection and review ranking. In order to improve the sharing precision, we introduce Convolutional Neural Network (CNN) into our clone detection, and design a novel CNN based clone searching module for our sharing system. Meanwhile, we adopt a heuristic filtering strategy to reduce the sharing time cost. We implement a prototype review sharing system RSharer and collect 72,440 code-review pairs as our ground knowledge. Empirical experiments on hundreds of real code fragments verify the effectiveness of RSharer. RSharer also achieves positive response and evaluation by expert developers.","Title: High Temporal Resolution Monitoring of Suspended Matter Changes from GOCI Measurements in Lake Taihu.\nYear: 2019\n\nAbstract: The Tiaoxi River is the main source of water for Lake Taihu and can result in plumes in the lake after heavy precipitation events. These plumes have played a crucial role in the water quality changes within the lake. High temporal resolution GOCI (Geostationary Ocean Color Imager) data were used to study the spatial distribution of the total suspended matter concentration in Lake Taihu after heavy precipitation events in the Tiaoxi River Basin via an empirical model. The plumes were analyzed after two heavy precipitation events in 2011 and 2013 using 16 GOCI images, which indicated that the Tiaoxi River had a great influence on the spatial distributions of total suspended matter and algal blooms. It was concluded that the main factors affecting the plumes in the Tiaoxi River were precipitation intensity, runoff, and total suspended matter concentration. Human activity, such as sand excavation also played a crucial role in sediment discharge. The results of this study demonstrate that the visualization of GOCI data makes it possible to use remote sensing technology to continuously monitor an inland water environment on an hourly scale, which is of great significance for studying the diffusion and evolution of river plumes.","Title: LISA: a MATLAB package for Longitudinal Image Sequence Analysis.\nYear: 2019\n\nAbstract: Large sequences of images (or movies) can now be obtained on an unprecedented scale, which poses fundamental challenges to the existing image analysis techniques. The challenges include heterogeneity, (automatic) alignment, multiple comparisons, potential artifacts, and hidden noises. This paper introduces our MATLAB package, Longitudinal Image Sequence Analysis (LISA), as a one-stop ensemble of image processing and analysis tool for comparing a general class of images from either different times, sessions, or subjects. Given two contrasting sequences of images, the image processing in LISA starts with selecting a region of interest in two representative images, followed by automatic or manual segmentation and registration. Automatic segmentation de-noises an image using a mixture of Gaussian distributions of the pixel intensity values, while manual segmentation applies a user-chosen intensity cut-off value to filter out noises. Automatic registration aligns the contrasting images based on a mid-line regression whereas manual registration lines up the images along a reference line formed by two user-selected points. The processed images are then rendered for simultaneous statistical comparisons to generate D, S, T, and P-maps. The D map represents a curated difference of contrasting images, the S map is the non-parametrically smoothed differences, the T map presents the variance-adjusted, smoothed differences, and the P-map provides multiplicity-controlled p-values. These maps reveal the regions with significant differences due to either longitudinal, subject-specific, or treatment changes. A user can skip the image processing step to dive directly into the statistical analysis step if the images have already been processed. Hence, LISA offers flexibility in applying other image pre-processing tools. LISA also has a parallel computing option for high definition images.","Title: Privacy-aware query processing in vehicular ad-hoc networks\nYear: 2019\n\nAbstract: Recently there is a research trend to integrate the cloud and the vehicular ad-hoc networks to enhance each other on the cooperative urban sensing applications. However, it remains a challenging problem on how to forward queries to search the results and then to route back the query results, as the vehicular nodes dynamically move on the road. Also, the dark side of vehicular cloud is often ignored. Getting the owner’s identity or locations of a given vehicle, or getting the queries submitted by vehicles would put the data privacy at risk. In this paper we propose a privacy preserving query processing scheme for vehicular sensor networks. The scheme consists of two phases: 1) at the index mapping phase, sensed data are stored locally at road side units (RSU), and a global index is maintained at the cloud; 2) at the query processing phase, queries are transformed based on a mapping function, and then are routed to the cloud. The cloud computes the set of RSUs that have the query result based on the mapping index, and then directs the query to the RSUs. Then the result forwarding is transformed into a query result forwarding problem at the RSU, where the data of query results are routed back at their best paths either through the 4G channel or through the DSRC (Dedicated Short Range Communication) channel. Also, the query results are encrypted and diffused to a set of RSUs that the query requester would travel along, so the requester could fetch the results before the query is outdated. Extensive experiments demonstrate the effectiveness of the proposed algorithm in vehicular sensor networks. The ratio of successful query delivery is higher than existing query schemes, while at the same time preserving the privacy of query requesters and the data owner in vehicular sensor networks.","Title: Simulation And Assessment Of The Capabilities Of Orbita Hyperspectral (Ohs) Imagery For Remotely Monitoring Chlorophyll-A In Eutrophic Plateau Lakes\nYear: 2021\n\nAbstract: The chlorophyll-a (Chl-a) concentration of eutrophic lakes fluctuates significantly due to the disturbance of wind and anthropogenic activities on the water body. Consequently, estimation of the Chl-a concentration has become an immense challenge. Due to urgent demand and rapid development in high-resolution earth observation systems, it has become crucial to assess hyperspectral satellite imagery capabilities on inland water monitoring. The Orbita hyperspectral (OHS) satellite is the latest hyperspectral sensor with both high spectral and spatial resolution (2.5 nm and 10 m, respectively), which could provide great potential for remotely estimating the concentration of Chl-a for inland waters. However, there are still some deficiencies that are mainly manifested in the Chl-a concentration remote sensing retrieval model assessment and accuracy validation, as well as signal-to-noise ratio (SNR) estimation of OHS imagery for inland waters. Therefore, the radiometric performance of OHS imagery for water quality monitoring is evaluated in this study by comparing different atmospheric correction models and the SNR with several remote sensing images. Several crucial findings can be drawn: (1) the three-band model ((1/B15-1/B17)B19) developed by OHS imagery is most suitable for estimating the Chl-a concentration in Dianchi Lake, with the root-mean-square error (RMSE) and the mean absolute percentage error (MAPE) of 15.55 mu g/L and 16.31%, respectively; (2) the applicability of the FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes) atmospheric correction model for OHS imagery in a eutrophic plateau lake (Dianchi Lake) was better than the 6S (Second Simulation of Satellite Signal in the Solar Spectrum) model, and QUAC (Quick Atmospheric Correction) model, as well as the dark pixel method; (3) the SNR of the OHS imagery was similar to that of Hyperion imagery and was significantly higher than SNR of the HSI imagery; (4) the spatial resolution showed slight influence on the SNR of the OHS imagery. The results show that OHS imagery could be applied to remote sensing retrieval of Chl-a in eutrophic plateau lakes and presents a new tool for dynamic hyperspectral monitoring of water quality.","Title: Evo-ViT: Slow-Fast Token Evolution for Dynamic Vision Transformer.\nYear: 2022\n\nAbstract: Vision transformers (ViTs) have recently received explosive popularity, but the huge computational cost is still a severe issue. Since the computation complexity of ViT is quadratic with respect to the input sequence length, a mainstream paradigm for computation reduction is to reduce the number of tokens. Existing designs include structured spatial compression that uses a progressive shrinking pyramid to reduce the computations of large feature maps, and unstructured token pruning that dynamically drops redundant tokens. However, the limitation of existing token pruning lies in two folds: 1) the incomplete spatial structure caused by pruning is not compatible with structured spatial compression that is commonly used in modern deep-narrow transformers; 2) it usually requires a time-consuming pre-training procedure. To tackle the limitations and expand the applicable scenario of token pruning, we present Evo-ViT, a self-motivated slow-fast token evolution approach for vision transformers. Specifically, we conduct unstructured instance-wise token selection by taking advantage of the simple and effective global class attention that is native to vision transformers. Then, we propose to update the selected informative tokens and uninformative tokens with different computation paths, namely, slow-fast updating. Since slow-fast updating mechanism maintains the spatial structure and information flow, Evo-ViT can accelerate vanilla transformers of both flat and deep-narrow structures from the very beginning of the training process. Experimental results demonstrate that our method significantly reduces the computational cost of vision transformers while maintaining comparable performance on image classification. For example, our method accelerates DeiT-S by over 60% throughput while only sacrificing 0.4% top-1 accuracy on ImageNet-1K, outperforming current token pruning methods on both accuracy and efficiency.","Title: Gis Partial Discharge Pattern Recognition Based On A Novel Convolutional Neural Networks And Long Short-Term Memory\nYear: 2021\n\nAbstract: Distinguishing the types of partial discharge (PD) caused by different insulation defects in gas-insulated switchgear (GIS) is a great challenge in the power industry, and improving the recognition accuracy of the relevant models is one of the key problems. In this paper, a convolutional neural network and long short-term memory (CNN-LSTM) model is proposed, which can effectively extract and utilize the spatiotemporal characteristics of PD input signals. First, the spatial characteristics of higher-level PD signals can be obtained through the CNN network, but because CNN is a deep feedforward neural network, it does not have the ability to process time-series data. The PD voltage signal is related to the time dimension, so LSTM saves and analyzes the previous voltage signal information, realizes the modeling of the time dependence of the data, and improves the accuracy of the PD signal pattern recognition. Finally, the pattern recognition results based on CNN-LSTM are given and compared with those based on other traditional analysis methods. The results show that the pattern recognition rate of this method is the highest, with an average of 97.9%, and its overall accuracy is better than that of other traditional analysis methods. The CNN-LSTM model provides a reliable reference for GIS PD diagnosis.","Title: CEBD: Contact-Evidence-Driven Blackhole Detection Based on Machine Learning in OppNets\nYear: 2021\n\nAbstract: Blackhole detection in the opportunistic networks offers an effective means to mitigate the routing performance degradation but faces many challenges from corrupted nodes due to their collusion behaviors. Most existing effort in the literature focuses on the blackhole feature extraction from the message exchange. However, the decay effect of features and the forged features from the corrupted node...","Title: Better Late Than Never: GAN-Enhanced Dynamic Anti-Jamming Spectrum Access With Incomplete Sensing Information\nYear: 2021\n\nAbstract: This letter studies the problem of anti-jamming spectrum access in dynamic and unknown environments with incomplete spectrum sensing information. Most existing studies were based on the assumption that users have perfect spectrum information, thus they worked poorly with incomplete sensing information. To overcome the shortcoming, we present a robust intelligent anti-jamming spectrum access scheme which includes spectrum sensing, completion, learning and access. To complete the missing spectrum data, we design a generative adversarial network (GAN) based spectrum completion network. Based on deep reinforcement learning (DRL), a channel selection network is introduced to choose effective anti-jamming channel access policy. Simulation results show that the proposed approach is able to avoid complex jamming attacks effectively and outperforms conventional DRL-based approach with incomplete spectrum information.","Title: Efficient Parallel Determinacy Race Detection for Structured Futures\nYear: 2021\n\nAbstract: ABSTRACTIn task-parallel code, a determinancy race occurs when two logically parallel instructions access the same memory location in a conflicting way. A determinacy race tends to be a bug as it leads to non-deterministic program behaviors. Researchers have studied algorithms for detecting determinacy races in task-parallel code, with most prior work focuses on computations with nice structural properties (e.g., fork-join or pipeline parallelism). For such computations, one can devise provably efficient algorithms with constant overhead, leading to a asymptotically optimal running time --- O(T_1 / P + T_∞) on P cores for a computation with T_1 work and T_∞ span. More recently, researchers have begun to address the problem of race detecting computations with less structural properties, such as ones that arise from the use of futures. Due to the lack of structural properties, the race detection algorithm incurs higher overhead. % Given a computation with work T_1 and span T_∞, the state-of-the-art parallel algorithm for race detecting programs with futures runs in time O((T_1 łgk + k^2) / P + T_∞(łg k + łgr łgk )) on P cores (Xu ηl, 2020), where k is the total number of futures used, k is the maximum number of future operations per \"future task,'' and r is the maximum number of readers between two consecutive writes to a given memory location. Interestingly, it has been shown that when one imposes certain restrictions on the use of futures, referred to as the structured futures, although the restrictions do not entirely eliminate arbitrary dependences among subcomputations, one can race detect such programs more efficiently than that for programs with general futures (i.e., no restrictions). The improved efficiency has only been demonstrated for a sequential algorithm (Utterback ηl, 2019) that race detects while executing the computation sequentially, however. The algorithm requires sequential execution, because the correctness of the algorithm relies on updating the necessary data structures while traversing the computation dag in a specific order. An interesting question remains, whether a parallel algorithm exists for race detecting programs with structured future that achieves better execution time compared to that designed for general futures. This work attempts to answer this question. We propose a parallel algorithm designed to race detect structured futures. By exploiting the restrictions imposed by structured futures, the proposed algorithm allows for a constant-time query while keeping fewer previous accessors around to provide the same correctness guarantees as prior work. Our algorithm runs in time O((T_1 + k^2)/P + T_∞ łg k) on P cores. We have also implemented and empirically evaluated the proposed algorithm. When compared to the state-of-the-art sequential algorithm designed for structured futures, although our algorithm has a longer one-core execution time, its absolute running time wins out when running on two cores or more. When compared to the state-of-the-art parallel algorithm designed for general futures, it indeed incurs lower overhead and performs better.","Title: Efficient Access History for Race Detection\nYear: 2021\n\nAbstract: ABSTRACTWhile there has been extensive research on race-detection algorithms for task-parallel programs, most of this research has focused on optimizing a particular component, namely, reachability analysis, which checks whether two instructions are logically in parallel. Little attention has been paid to the other important component, the access history, which stores all memory locations previous instructions have accessed. In theory, the access-history component adds no asymptotic overhead; however, in practice, it is often the most expensive component of race detection since it is queried and (possibly) updated at each memory access. We optimize this component based on the observation that, typically, strands within parallel programs access contiguous blocks of memory. Therefore, instead of maintaining the access history at the granularity of individual memory locations, we maintain it at the granularity of these (varying size) intervals. To enable this access history, we propose (1) compiler and runtime mechanisms that allow us to efficiently collect these intervals and (2) a tree-based access-history data structure that allows updates and queries at interval granularity. The resulting tool can race-detect fork-join code with amortized constant overhead, assuming the number of intervals is small compared to the total work of the computation.","Title: Tree Extraction From Airborne Laser Scanning Data In Urban Areas\nYear: 2021\n\nAbstract: Tree information in urban areas plays a significant role in many fields of study, such as ecology and environmental management. Airborne LiDAR scanning (ALS) excels at the fast and efficient acquisition of spatial information in urban-scale areas. Tree extraction from ALS data is an essential part of tree structural studies. Current raster-based methods that use canopy height models (CHMs) suffer from the loss of 3D structure information, whereas the existing point-based methods are non-robust in complex environments. Aiming at making full use of the canopy's 3D structure information that is provided by point cloud data, and ensuring the method's suitability in complex scenes, this paper proposes a new point-based method for tree extraction that is based on 3D morphological features. Considering the elevation deviations of the ALS data, we propose a neighborhood search method to filter out the ground and flat-roof points. A coarse extraction method, combining planar projection with a point density-filtering algorithm is applied to filter out distracting objects, such as utility poles and cars. After that, a Euclidean cluster extraction (ECE) algorithm is used as an optimization strategy for coarse extraction. In order to verify the robustness and accuracy of the method, airborne LiDAR data from Zhangye, Gansu, China and unmanned aircraft vehicle (UAV) LiDAR data from Xinyang, Henan, China were tested in this study. The experimental results demonstrated that our method was suitable for extracting trees in complex urban scenes with either high or low point densities. The extraction accuracy obtained for the airborne LiDAR data and UAV LiDAR data were 99.4% and 99.2%, respectively. In addition, a further study found that the aberrant vertical structure of the artificially pruned canopy was the main cause of the error. Our method achieved desirable results in different scenes, with only one adjustable parameter, making it an easy-to-use method for urban area studies.","Title: Fairness Maximization Among Offline Agents in Online-Matching Markets\nYear: 2021\n\nAbstract: Matching markets involve heterogeneous agents (typically from two parties) who are paired for mutual benefit. During the last decade, matching markets have emerged and grown rapidly through the medium of the Internet. They have evolved into a new format, called Online Matching Markets (OMMs), with examples ranging from crowdsourcing to online recommendations to ridesharing. There are two features distinguishing OMMs from traditional matching markets. One is the dynamic arrival of one side of the market: we refer to these as online agents while the rest are offline agents. Examples of online and offline agents include keywords (online) and sponsors (offline) in Google Advertising; workers (online) and tasks (offline) in Amazon Mechanical Turk (AMT); riders (online) and drivers (offline when restricted to a short time window) in ridesharing. The second distinguishing feature of OMMs is the real-time decision-making element. However, studies have shown that the algorithms making decisions in these OMMs leave disparities in the match rates of offline agents. For example, tasks in neighborhoods of low socioeconomic status rarely get matched to gig workers, and drivers of certain races/genders get discriminated against in matchmaking. In this paper, we propose online matching algorithms which optimize for either individual or group-level fairness among offline agents in OMMs. We present two linear-programming (LP) based sampling algorithms, which achieve online competitive ratios at least 0.725 for individual fairness maximization (IFM) and 0.719 for group fairness maximization (GFM), respectively. We conduct extensive numerical experiments and results show that our boosted version of sampling algorithms are not only conceptually easy to implement but also highly effective in practical instances of fairness-maximization-related models.","Title: FAMGAN: Fine-grained AUs Modulation based Generative Adversarial Network for Micro-Expression Generation\nYear: 2021\n\nAbstract: ABSTRACTMicro-expressions (MEs) are significant and effective clues to reveal the true feelings and emotions of human beings, and thus MEs analysis is widely used in different fields such as medical diagnosis, interrogation and security. However, it is extremely difficult to elicit and label MEs, resulting in a lack of sufficient MEs data for MEs analysis. To address this challenge and inspired by the current face generation technology, in this paper we introduce Generative Adversarial Network based on fine-grained Action Units (AUs) modulation to generate MEs sequence (FAMGAN). Specifically, after comprehensively analyzing the factors that lead to inaccurate AU values detection, we performed fine-grained AUs modulation, which includes carefully eliminating the various noises and dealing with the asymmetry of AUs intensity. Additionally, we incorporate super-resolution into our model to enhance the quality of the generated images. Through experiments, we show that the system achieves very competitive results on the Micro-Expression Grand Challenge (MEGC2021).","Title: TSOR: Thompson Sampling-Based Opportunistic Routing\nYear: 2021\n\nAbstract: Routing is a fundamental problem and has been extensively studied in various networks. However, in highly dynamic networks (e.g., wireless ad hoc networks), nodes have limited transmission opportunities due to high mobility, noise and interference, where traditional routing is often not the best approach. Opportunistic routing (OR), on the other hand, can effectively minimize the ...","Title: RFNet - Recurrent Forward Network for Dense Point Cloud Completion.\nYear: 2021\n\nAbstract: Point cloud completion is an interesting and challenging task in 3D vision, aiming to recover complete shapes from sparse and incomplete point clouds. Existing learning-based methods often require vast computation cost to achieve excellent performance, which limits their practical applications. In this paper, we propose a novel Recurrent Forward Network (RFNet), which is composed of three modules: Recurrent Feature Extraction (RFE), Forward Dense Completion (FDC) and Raw Shape Protection (RSP). The RFE extracts multiple global features from the incomplete point clouds for different recurrent levels, and the FDC generates point clouds in a coarse-to-fine pipeline. The RSP introduces details from the original incomplete models to refine the completion results. Besides, we propose a Sampling Chamfer Distance to better capture the shapes of models and a new Balanced Expansion Constraint to restrict the expansion distances from coarse to fine. According to the experiments on ShapeNet and KITTI, our network can achieve the state-of-the-art with lower memory cost and faster convergence.","Title: Energy-Efficient Channel Access and Data Offloading Against Dynamic Jamming Attacks\nYear: 2021\n\nAbstract: Multi-access edge computing (MEC) system is developing to take advantage of the adjacent computation devices to reach better performance for IoT networks, and has to fight against malicious jamming attacks and heavy co-channel interference. To address this issue, this paper investigates the energy-efficient MEC optimization problem in a jamming environment where the attack activities of the jammer...","Title: Equity Promotion in Online Resource Allocation.\nYear: 2022\n\nAbstract: We consider online resource allocation under a typical non-profit setting, where limited or even scarce resources are administered by a not-for-profit organization like a government. We focus on the internal-equity by assuming that arriving requesters are homogeneous in terms of their external factors like demands but heterogeneous for their internal attributes like demographics. Specifically, we associate each arriving requester with one or several groups based on their demographics (i.e., race, gender, and age), and we aim to design an equitable distributing strategy such that every group of requesters can receive a fair share of resources proportional to a preset target ratio. We present two LP-based sampling algorithms and investigate them both theoretically (in terms of competitive-ratio analysis) and experimentally based on real COVID-19 vaccination data maintained by the Minnesota Department of Health. Both theoretical and numerical results show that our LP-based sampling strategies can effectively promote equity, especially when the arrival population is disproportionately represented, as observed in the early stage of the COVID-19 vaccine rollout.","Title: A multi-agent reinforcement learning anti-jamming method with partially overlapping channels\nYear: 2021\n\nAbstract: This paper investigates the problem of multi-user anti-jamming channel access with partially overlapping channels (POC). Compared with traditional anti-jamming systems that use non-overlapping channels, POC improve the spectral efficiency. However, the partial overlap of channels also brings more serious interference. For this, physical distance and channel separation on the interference intensity under partially overlapping channels are first considered and the malicious jamming and interference among users are formulated as a hierarchical binary model. Secondly, to cope with multi-user decisions under dynamic jamming conditions, the Markov game framework is adopted to analyse the problem. Thirdly, a multi-user collaborative anti-jamming channel selection algorithm based on reinforcement learning is proposed as well as the optimal anti-jamming strategy can be obtained. Finally, the simulation results validate that the proposed algorithm helps users cope with jamming and eliminate mutual interference. Compared with the non-overlapping channel access scheme, the POC access scheme achieves higher network throughput.","Title: Primary-User-Friendly Dynamic Spectrum Anti-Jamming Access: A GAN-Enhanced Deep Reinforcement Learning Approach\nYear: 2022\n\nAbstract: This letter studies the problem of deep reinforcement learning (DRL)-based dynamic spectrum anti-jamming access in overlay cognitive radio networks. To prevent secondary user (SU) from interfering with primary user (PU) and being jammed by jammer, we propose a PU-friendly dynamic spectrum anti-jamming access scheme. First, a generative adversarial network (GAN)-based virtual environment is proposed to simulate spectrum environment. Then, a DRL-based channel decision network (CDN) is trained to learn the optimal spectrum access policy in the virtual environment. Finally, SU accesses spectrum environment under the guidance of the trained CDN. Simulation results show that the proposed scheme is able to elude both PU signals and jamming completely and converges much faster than the scheme that trains the CDN in spectrum environment from scratch.","Title: Play it by Ear: Context-Aware Distributed Coordinated Anti-Jamming Channel Access\nYear: 2021\n\nAbstract: This paper investigates the anti-jamming problems in wireless communication networks. In these networks consisted of multiple devices (users), there exist two critical problems. On the one hand, users with various transmission requirements should coordinate their channel selection strategies distributedly to avoid spectrum conflicts and satisfy transmission demands. On the other hand, they also need to fully consider how to eliminate the effects of malicious attacks. To cope with the internal coordination and external confrontation challenges and accommodate the dynamic changing jamming attacks, a context-aware distributed coordinated anti-jamming channel access mechanism is proposed, which means for different cases of jamming attacks, different access strategies are adopted. In detail, to reflect the heterogeneous communication demands of users, the transmission satisfaction function is firstly introduced. Then, the multi-user anti-jamming scenario is modeled as a context-aware multi-pattern dynamic anti-jamming game, which can be decomposed into two sub-games. Here, for the case that the control channel is available, a local altruistic sub-game is introduced. While for the case that the control channel has been jammed, an anti-jamming congestion sub-game is designed. Besides, the existence of Nash Equilibriums is demonstrated. To obtain NEs, a context-aware distributed channel access (CDCA) algorithm is designed. Through game-theoretic analysis and distributed learning, global transmission satisfaction can be improved under the dynamic jamming environment. Furthermore, the fairness of the network can also be guaranteed.","Title: Optimized Large-Scale Road Sensing Through Crowdsourced Vehicles\nYear: 2022\n\nAbstract: Modern vehicles are gradually becoming powerful mobile sensing, communication, computing and storage platforms, which bring about the concept of vehicular urban sensing that leverages sensor nodes as an effective and affordable solution for large-scale and fine-grained sensing. And there is a trend to combine the vehicular sensing and outsourcing technologies to solve the large-scale urban road se...","Title: Proceed From Known to Unknown: Jamming Pattern Recognition Under Open-Set Setting\nYear: 2022\n\nAbstract: In this letter, we study the problem of jamming pattern recognition (JPR) when some patterns have no training samples. Existing works were designed for recognition of known jamming patterns only, hence they failed to deal with unknown jamming patterns. To address this challenge, a zero-shot learning (ZSL) based JPR scheme is proposed. Firstly, a supervised training process is introduced to learn t...","Title: Joint flight scheduling and task allocation for secure data collection in UAV-aided IoTs\nYear: 2022\n\nAbstract: With the flexible mobility and deployment, Unmanned Aerial Vehicles (UAVs) have created a new dimension to provide data collection services for a large number of distributed wireless sensory devices. Unfortunately, the broadcast nature of wireless channels make it hard to guarantee the security of data transmission in Internet of Things (IoTs). In this paper, focusing on the scenario where potential eavesdroppers intend to intercept the data uploading of legitimate nodes, we take the advantages of the UAV technology and the physical-layer security approach to study the Secure Data Collection Problem (SDCP). We first explore the flight scheduling and task allocation, that is, determining which areas to be visited and who to be served by UAVs, to establish favorable communication channels. Then we set up the utility function with secrecy rates and non-negative budget constraints. Due to the coupling between the UAV scheduling and task allocation optimization variables in the SDCP, we construct a surrogate function to achieve decoupling and reformulate SDCP into the SDCP-m problem, which is analyzed and proved to be a nonnegative monotone submodular function subject to a general constraint. Finally, an efficient Cost-Benefit Greedy (CBG) algorithm, which is theoretically analyzed to seek the quantitative value of approximation ratio, is proposed. The simulation results show that the CBG algorithm not only outperforms benchmark algorithms in terms of the average secrecy rate and the iteration number, but also generates a nearly optimal trajectory.","Title: Joint channel and power optimisation for multi-user anti-jamming communications: A dual mode Q-learning approach\nYear: 2022\n\nAbstract: In view of the anti-tracking-jamming problem, traditional online learning methods usually cannot analyse the jamming behaviour, and find an effective way to prevent the jamming attacks. To cope with these challenges, a novel communication/deception dual mode mechanism is proposed in this paper. Deception users are selected to send high-power signal for jamming attraction, and form collaborative relationships with communication users. The corresponding collaborative anti-jamming model is then constructed as a Markov game to analyse the multi-agent decision. Based on that, a joint channel and power optimisation for multi-user anti-jamming communications based on dual mode Q-learning scheme is proposed. Compared with two traditional online learning algorithms, the proposed DCAJ-QL algorithm effectively achieves 146.5% and 80.4% higher maximum communication rate under tracking jamming conditions, and achieves 40.7% and 53.6% higher maximum communication rate under fixed jamming conditions.","Title: Providers-Clients-Robots: Framework for spatial-semantic planning for shared understanding in human-robot interaction.\nYear: 2022\n\nAbstract: This paper develops a novel framework called Providers-Clients-Robots (PCR), applicable to socially assistive robots that support research on shared understanding in human-robot interactions. Providers, Clients, and Robots share an actionable and intuitive representation of the environment to create plans that best satisfy the combined needs of all parties. The plans are formed via interaction between the Client and the Robot based on a previously built multi-modal navigation graph. The explainable environmental representation in the form of a navigation graph is constructed collaboratively between Providers and Robots prior to interaction with Clients. We develop a realization of the proposed framework to create a spatial-semantic representation of an indoor environment autonomously. Moreover, we develop a planner that takes in constraints from Providers and Clients of the establishment and dynamically plans a sequence of visits to each area of interest. Evaluations show that the proposed realization of the PCR framework can successfully make plans while satisfying the specified time budget and sequence constraints and outperforming the greedy baseline.","Title: A Novel Method for Pattern Recognition of GIS Partial Discharge via Multi-Information Ensemble Learning\nYear: 2022\n\nAbstract: Partial discharge (PD) is the main feature that effectively reflects the internal insulation defects of gas-insulated switchgear (GIS). It is of great significance to diagnose the types of insulation faults by recognizing PD to ensure the normal operation of GIS. However, the traditional diagnosis method based on single feature information analysis has a low recognition accuracy of PD, and there are great differences in the diagnosis effect of various insulation defects. To make the most of the rich insulation state information contained in PD, we propose a novel multi-information ensemble learning for PD pattern recognition. First, the ultra-high frequency and ultrasonic data of PD under four typical defects of GIS are obtained through experiment. Then the deep residual convolution neural network is used to automatically extract discriminative features. Finally, multi-information ensemble learning is used to classify PD types at the decision level, which can complement the shortcomings of the independent recognition of the two types of feature information and has higher accuracy and reliability. Experiments show that the accuracy of the proposed method can reach 97.500%, which greatly improves the diagnosis accuracy of various insulation defects.","Title: XDAI: A Tuning-free Framework for Exploiting Pre-trained Language Models in Knowledge Grounded Dialogue Generation\nYear: 2022\n\nAbstract: Large-scale pre-trained language models (PLMs) have shown promising advances on various downstream tasks, among which dialogue is one of the most concerned. However, there remain challenges for individual developers to create a knowledge-grounded dialogue system upon such big models because of the expensive cost of collecting the knowledge resources for supporting the system as well as tuning these large models for the task. To tackle these obstacles, we propose XDAI, a knowledge-grounded dialogue system that is equipped with the prompt-aware tuning-free PLM exploitation and supported by the ready-to-use open-domain external knowledge resources plus the easy-to-change domain-specific mechanism. With XDAI, the developers can leverage the PLMs without any fine-tuning cost to quickly create the open-domain dialogue systems as well as easily customize their own domain-specific systems. Extensive experiments including human evaluation, Turing test, and online evaluation have demonstrated the competitive performance of XDAI compared with the state-of-the-art general PLMs and specific PLMs for dialogue. XDAI pilots studies on the exploitation of PLMs and made intriguing findings which could be inspiring for the future research on other PLM-based applications. Developers and related researchers can get access to our repository at https://github.com/THUDM/XDAI, which presents a series of APIs, incremental toolkits and chatbot service of XDAI platform.","Title: Accelerated Sampling Research Under Task Optimized Strategy for Multistate Systems\nYear: 2022\n\nAbstract: The complex multi-state systems joint operation simulation and two task strategies are explored. For Monte Carlo sampling, based on the indirect sampling method, the principle of accelerated sampling methods (ASM), including forced transition (FT) and fault biasing (FB), is studied. It is found that the direct adoption of the current FT and FB will result in systematic bias for the calculation of task success metrics. For the bias, a state-transition chain truncation rule (SCTR) is proposed. In case study, after the simulation of various parameter combinations, it is found that when the sailing time is relatively smaller than the equipment reliability, which means a small probability event for the sampling of equipment faults, the ASM based on indirect sampling is applicable. Otherwise, the conventional sampling method should be used. The proposed state-transition chain truncation rule is also verified in case study.","Title: Resilient Participant Selection Under Vulnerability Induced Colluding Attacks for Crowdsourcing\nYear: 2022\n\nAbstract: This paper investigates the problem of participant selection considering colluding attacks for crowdsourcing. Compared with existing work, a practical vulnerability-induced colluding attack model is considered, where the malicious participants with different vulnerability levels collude with each other to perform attacks, which makes the participant selection problem more challenging. To address this problem, according to the structural characteristics of the colluding attack model, we derive the necessary condition and sufficient condition of achieving the colluding possibility minimization of the selected participants. A novel resilient participant selection algorithm is developed based on the necessary condition and sufficient condition. The proposed algorithm can select participants to complete tasks with the time complexity \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$O(mn)$</tex-math></inline-formula>\n, where \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><tex-math notation=\"LaTeX\">$m, n$</tex-math></inline-formula>\n are the numbers of participants and tasks, respectively. We analyze that the proposed algorithm achieves the colluding possibility minimization to defeat the vulnerability-induced colluding attack. It is also analyzed that the social cost of the proposed algorithm is smaller than existing algorithms in terms of the task-performing cost and the potential damage of the colluding attacks. Extensive real-world trace-based simulations are conducted to demonstrate the effectiveness of the proposed algorithm and the correctness of the theoretical results.","Title: PINT: Parallel INTerval-Based Race Detector\nYear: 2022\n\nAbstract: A race detector for task-parallel code typically consists of two main components - a reachability analysis component that checks whether two instructions are logically in parallel and an access history component that keeps track of memory locations accessed by previous instructions. Race detectors from prior work typically utilize a hashmap to maintain the access history, which provides asymptotically optimal overhead per operation but can incur significant overhead in practice, since the detector needs to insert into and query the hashmap for every memory access. An exception is STINT by Xu et al., which race detects task-parallel code by coalescing memory accesses into intervals, or continuous memory locations accessed within a sequence of instructions without any parallel construct. STINT utilizes a treap to manage access history that allows for insertions and queries of non-overlapping intervals. While a treap incurs higher asymptotic overhead per operation, this strategy works well in practice as the race detector performs operation on the access history with much lower frequency compared to the strategy that utilizes a hashmap. STINT only executes task-parallel code sequentially, however, due to the unique design of their treap that ensures no overlapping intervals exist in the tree. Parallelizing STINT efficiently is non-trivial, as it would require a concurrent treap that ensures no overlapping interval, which is challenging to design and likely incurs high synchronization overhead. This work proposes PINT, a race detector that, like STINT, race detects task-parallel code at the interval granularity and utilizes the same treap design to maintain access history. PINT executes the computation in parallel, however, while keeping the parallelization / synchronization overhead low. A key insight is that, PINT separates out operations needed for race detection into the core part (e.g., reachability maintenance) and the access history part. Doing so allows PINT to parallelize the core part efficiently and perform the access history part asynchronously, thereby incurring low overhead.","Title: Fine-grained Micro-Expression Generation based on Thin-Plate Spline and Relative AU Constraint\nYear: 2022\n\nAbstract: ABSTRACTAs a typical psychological stress reaction, micro-expression (ME) is usually quickly leaked on a human face and can reveal the true feeling and emotional cognition. Therefore,automatic ME analysis (MEA) has essential applications in safety, clinical and other fields. However, the lack of adequate ME data has severely hindered MEA research. To overcome this dilemma and encouraged by current image generation techniques, this paper proposes a fine-grained ME generation method to enhance ME data in terms of data volume and diversity. Specifically, we first estimate non-linear ME motion using thin-plate spline transformation with a dense motion network. Then, the estimated ME motion transformations, including optical flow and occlusion masks, are sent to the generation network to synthesize the target facial micro-expression. In particular, we obtain the relative action units (AUs) of the source ME to the target face as a constraint to encourage the network to ignore expression-irrelevant movements, thereby generating fine-grained MEs. Through comparative experiments on CASME II, SMIC and SAMM datasets, we demonstrate the effectiveness and superiority of our method. Source code is provided in https://github.com/MEA-LAB-421/MEGC2022-Generation.","Title: Inconsistency-Based Multi-Task Cooperative Learning for Emotion Recognition\nYear: 2022\n\nAbstract: Emotion recognition is an important part of affective computing. Human emotions can be described categorically or dimensionally. Accurate machine learning models for emotion classification and estimation usually depend on a large amount of annotated data. However, label acquisition in emotion recognition is costly: obtaining the ground-truth labels of an emotional sample usually requires multiple annotators’ assessments, which is expensive and time-consuming. To reduce the labeling effort in multi-task emotions recognition, the paper proposes an inconsistency measure that can indicate the difference between the labels estimated from the feature space and the label distribution of labeled dataset. Using the inconsistency as an indicator of sample informativeness, we further propose an inconsistency-based multi-task cooperative learning framework that integrates multi-task active learning and self-training semi-supervised learning. Experiments in two multi-task emotion recognition scenarios, multi-dimensional emotion estimation and simultaneous emotion classification and estimation, were conducted under this framework. The results demonstrated that the proposed multi-task active learning framework outperformed several single-task and multi-task active learning approaches."],"string":"[\n \"Title: The Algorithm of Sequential KKT Equations by Nonmonotone Search for Arbitrary Initial Point\\nYear: 2001\\n\\nAbstract: In this paper, a new algorithm for arbitrary initial point is proposed. The feature of the algorithm is that only KKT equations are solved in each iteration which greatly decreases the amount of computation. Under some proper assumptions, the algorithm is globally and superlinearly convergent.\",\n \"Title: A nonlinear Lagrangian dual for integer programming\\nYear: 2002\\n\\nAbstract: Nonlinear Lagrangian theory offers a success guarantee for the dual search via construction of a nonlinear support of the perturbation function at the optimal point. In this paper, a new nonlinear dual formulation of an exponential form is proposed for bounded integer programming. This new formulation possesses an asymptotic strong duality property and guarantees a success in identifying a primal optimum solution. No actual dual search is needed in the solution process when the parameter of the nonlinear Lagrangian formulation is set to be large enough.\",\n \"Title: Generalized Nonlinear Lagrangian Formulation for Bounded Integer Programming\\nYear: 2005\\n\\nAbstract: Several nonlinear Lagrangian formulations have been recently proposed forbounded integer programming problems. While possessing an asymptotic strong dualityproperty, these formulations offer a success guarantee for the identification of an optimalprimal solution via a dual search. Investigating common features of nonlinear Lagrangianformulations in constructing a nonlinear support for nonconvex piecewise constant perturbation function, this paper proposes a generalized nonlinear Lagrangian formulation of which many existing nonlinear Lagrangian formulations become special cases.\",\n \"Title: Asymptotic strong determination in integer programming: Quasi dual method\\nYear: 2003\\n\\nAbstract: . Although the Lagrangian method is a powerful dual search method in integer programming, it often fail to identify the optimal\\n solution of the primal problem. In this paper, a quasi dual formulation is proposed for bounded integer programming. This\\n formulation possesses an asymptotic strong determination property and guarantees a success for identifying an optimum solution.\\n Its another feature is that no actual dual search is needed when the parameters of the method are set to be large enough.\",\n \"Title: Contamination control in food supply chain\\nYear: 2010\\n\\nAbstract: In this paper, we study a contamination control problem in food supply chain. We formulate the problem as a dynamic programming problem and then study the structure of the optimal control which turns out to be very similar to the hedging-point type of policy. Under the environment in which there is uncertainty associated with contamination control, we propose a stochastic dynamic programming formulation with chance constraints, to which simulation based methods could be applied.\",\n \"Title: On the tour planning problem.\\nYear: 2012\\n\\nAbstract: Increasingly, tourists are planning trips by themselves using the vast amount of information available on the Web. However, they still expect and want trip plan advisory services. In this paper, we study the tour planning problem in which our goal is to design a tour trip with the most desirable sites, subject to various budget and time constraints. We first establish a framework for this problem, and then formulate it as a mixed integer linear programming problem. However, except when the size of the problem is small, say, with less than 20-30 sites, it is computationally infeasible to solve the mixed-integer linear programming problem. Therefore, we propose a heuristic method based on local search ideas. The method is efficient and provides good approximation solutions. Numerical results are provided to validate the method. We also apply our method to the team orienteering problem, a special case of the tour planning problem which has been considered in the literature, and compare our method with other existing methods. Our numerical results show that our method produces very good approximation solutions with relatively small computational efforts comparing with other existing methods. © 2010 Springer Science+Business Media, LLC.\",\n \"Title: A mixed and superlinearly convergent algorithm for constrained optimization\\nYear: 2003\\n\\nAbstract: In this paper, a mixed QP-free method for constrained optimization problem is proposed. This new method consists of two different sub-methods, sub-method I and sub-method II. These two sub-methods are all QP-free. A switch is designed to decide which sub-method should be adopted in each iteration. Under some mild assumptions, we prove that the method is globally and superlinearly convergent.\",\n \"Title: Simple transformation functions for finding better minima\\nYear: 2008\\n\\nAbstract: This work presents two transformation functions, the α-function and the M-function, for finding better minimizers in global optimization. We prove that under some general assumptions these functions possess the characters of both tunnelling functions and filled functions. Numerical tests from some test functions show that our transformation functions are very effective in finding better minima.\",\n \"Title: Stochastic control via direct comparison\\nYear: 2011\\n\\nAbstract: The standard approach to stochastic control is dynamic programming. In this paper, we introduce an alternative approach based on direct comparison of the performance of any two policies. This is achieved by modeling the state process as a continuous-time and continuous-state Markov process and applying the same ideas as for the discrete-time and discrete-state case. This approach is simple and intuitively clear; it applies to different problems with, finite and infinite horizons, discounted and long-run-average performance, continuous and jump diffusions, in the same way. Discounting is not needed when dealing with long-run average performance. The approach provides a unified framework for stochastic control and other optimization theory and methodologies, including Markov decision processes, perturbation analysis, and reinforcement learning.\",\n \"Title: Implicit Multifunction Theorems in Banach Spaces.\\nYear: 2014\\n\\nAbstract: This paper is mainly devoted to the study of implicit multifunction theorems in terms of Clarke coderivative in general Banach spaces. We present new sufficient conditions for the local metric regularity, metric regularity, Lipschitz-like property, nonemptiness, and lower semicontinuity of implicit multifunctions in general Banach spaces. The basic tools of our analysis involve the Ekeland variational principle, the Clarke subdifferential, and the Clarke coderivative.\",\n \"Title: Dynamic inventory and pricing policy in a capacitated stochastic inventory system with fixed ordering cost.\\nYear: 2012\\n\\nAbstract: We study a dynamic inventory and pricing optimization problem in a periodic review inventory system with setup cost and finite ordering capacity in each period. We show that the optimal inventory control is characterized by an (s,s′,p) policy in four regions of the starting inventory level.\",\n \"Title: Openness results for parametric set-valued mappings in Asplund spaces.\\nYear: 2014\\n\\nAbstract: In this paper, we first prove a lemma about the lower semicontinuity of the distance function in infinite dimensional spaces, which is crucial to openness results hereafter. Then we obtain some openness results in terms of Frechet coderivatives for parametric set-valued mappings in Asplund spaces under mild conditions. The results of the paper generalize several corresponding results in the recent literature. Finally, we give two examples to illustrate our openness results.\",\n \"Title: Non-cooperative Resource Allocation Scheme for Data Access in VANET Cloud Environment\\nYear: 2015\\n\\nAbstract: Data dissemination, especially large amount of data transmission, has become one of the main tasks for the selfish vehicle nodes in Vehicular Ad hoc Networks (VANETs). Exploiting the Road Side Unites (RSUs), which construct the Cloud Computing environment, provides more data access opportunities and stable communication time for the vehicles. However, due to the high mobility of the vehicles and the frequent changes in the network topology, the flow rate of the vehicles for multimedia data access may fluctuate, leading to the high transmission latency. In this paper, the cloud resource allocation for data access is investigated with the non-cooperative cloud resource allocation game based on Gauss-Seidel iteration method. Specifically, an on-demand precision control strategy is proposed to achieve the iteration precision of the flow control. The analysis based on these models lays a theoretical method foundation on the noncooperative game computing process. Furthermore, two common methods for calculating the Nash Equilibrium Point (NEP) of the cloud resource allocation game are compared based on the analytical results. The validity of the modeling and the accuracy of the analysis are verified through the extensive simulations, which also guide the design of more sophisticated cloud resource allocation schemes.\",\n \"Title: A Nanoporous Alumina Membrane Based Electrochemical Biosensor for Histamine Determination with Biofunctionalized Magnetic Nanoparticles Concentration and Signal Amplification.\\nYear: 2016\\n\\nAbstract: Histamine is an indicator of food quality and indispensable in the efficient functioning of various physiological systems. Rapid and sensitive determination of histamine is urgently needed in food analysis and clinical diagnostics. Traditional histamine detection methods require qualified personnel, need complex operation processes, and are time-consuming. In this study, a biofunctionalized nanoporous alumina membrane based electrochemical biosensor with magnetic nanoparticles (MNPs) concentration and signal amplification was developed for histamine determination. Nanoporous alumina membranes were modified by anti-histamine antibody and integrated into polydimethylsiloxane (PDMS) chambers. The specific antibody modified MNPs were used to concentrate histamine from samples and transferred to the antibody modified nanoporous membrane. The MNPs conjugated to histamine were captured in the nanopores via specific reaction between histamine and anti-histamine antibody, resulting in a blocking effect that was amplified by MNPs in the nanopores. The blockage signals could be measured by electrochemical impedance spectroscopy across the nanoporous alumina membrane. The sensing platform had great sensitivity and the limit of detection (LOD) reached as low as 3 nM. This biosensor could be successfully applied for histamine determination in saury that was stored in frozen conditions for different hours, presenting a potentially novel, sensitive, and specific sensing system for food quality assessment and safety support.\",\n \"Title: An Alarm Flood Pattern Matching Algorithm Based On Modified Blast With Leveshtein Distance\\nYear: 2016\\n\\nAbstract: Alarm flooding is one of the main problems in alarm management. Alarm flood pattern analysis is helpful for root cause analysis of historical floods and for incoming flood prediction. This paper introduces a data driven method for alarm flood pattern matching. A modified BLAST algorithm with Levenshtein distance is proposed to discover similar alarm floods. A quadruple tank process is simulated to test the effectiveness of the proposed algorithm. The results show that the algorithm is quick and accurate.\",\n \"Title: A resource allocation game with restriction mechanism in VANET cloud.\\nYear: 2017\\n\\nAbstract: In Vehicular Ad hoc Networks (VANETs), because of the selfishness of the vehicles, the resource allocation in VANET has become one of the primary tasks. Exploiting the Road Side Units (RSUs), which constructs the Cloud Computing environment, provides more data access opportunities and stable communication time for the vehicles. We investigated the cloud resource allocation for data access with noncooperative game based on a Gauss-Seidel iteration method. We further proposed a repeated game scheme, which can approximately achieve the near Pareto-optimal flow allocation among the vehicles. Considering the vehicles' irrational behavior, a punishment strategy was designed to prevent the vehicles from behavior deviation. The analysis based on these models lays a theoretical method foundation on cloud resource allocation process. The validity of the modeling and the accuracy of the analysis were verified through the extensive simulations, which also guide the future design of more sophisticated cloud resource allocation schemes. Copyright (C) 2016 John Wiley & Sons, Ltd.\",\n \"Title: Data Gathering Framework Based On Fog Computing Paradigm In Vanets\\nYear: 2017\\n\\nAbstract: Vehicular nodes are equipped with more and more sensing units, and large amount of sensing data are generated. This makes the data gathering and monitoring is a challenging problem in VANETs. In this paper we first present an sensing and data gathering framework through the concept of fog computing in VANETs, then we propose an event-based data gathering scheme based on this framework that adaptively adjusts the threshold to upload suitable amount of data for decision making, while at the same time suppress unnecessary message transmissions. Preliminary experiments demonstrate the effectiveness of the proposed algorithm in vehicular sensing applications.\",\n \"Title: Location-Aware Worker Selection for Mobile Opportunistic Crowdsensing in VANETs.\\nYear: 2017\\n\\nAbstract: Worker selection for location-based crowdsensing can be described as the strategy of choosing the proper cooperative participants to complete the allocated tasks in specified regions. Due to the mobility pattern of vehicles and regular road networks, the Vehicular Ad-hoc Networks (VANETs) are expected to provide many opportunities for task execution in opportunistic crowdsensing, enabling some emerging applications. To fulfill tasks with the least execution time under the spatial-temporal restrictions, we propose a Location-Aware Worker Selection scheme (LAWS) for mobile opportunistic crowdsensing in urban areas. Different from the traditional worker selection schemes assigning a task to one designated worker, LAWS exploits the vehicles contacts provided by taxicabs and buses and makes full advantage of prior knowledge of vehicles to promote the performance of task execution. Real-world vehicle traces are introduced to construct the extensive simulations. The simulation results show that our scheme outperforms the well-known algorithms, e.g., Epidemic, Prophet, in terms of the task execution success ratio, the execution time and the network load.\",\n \"Title: Efficient parallel determinacy race detection for two-dimensional dags.\\nYear: 2018\\n\\nAbstract: A program is said to have a determinacy race if logically parallel parts of a program access the same memory location and one of the accesses is a write. These races are generally bugs in the program since they lead to non-deterministic program behavior --- different schedules of the program can lead to different results. Most prior work on detecting these races focuses on a subclass of programs with fork-join parallelism.\\n\\nThis paper presents a race-detection algorithm, 2D-Order, for detecting races in a more general class of programs, namely programs whose dependence structure can be represented as planar dags embedded in 2D grids. Such dependence structures arise from programs that use pipelined parallelism or dynamic programming recurrences. Given a computation with T1 work and T∞ span, 2D-Order executes it while also detecting races in O(T1/P + T∞) time on P processors, which is asymptotically optimal.\\n\\nWe also implemented PRacer, a race-detection algorithm based on 2D-Order for Cilk-P, which is a language for expressing pipeline parallelism. Empirical results demonstrate that PRacer incurs reasonable overhead and exhibits scalability similar to the baseline (executions without race detection) when running on multiple cores.\",\n \"Title: Improved Benders Decomposition For Capacitated Hub Location Problem With Incomplete Hub Networks\\nYear: 2017\\n\\nAbstract: The hub location problem (HLP) has been studied by researchers for many years. A number of model variants and solution techniques for solving the problem have been proposed. Most researchers consider the uncapacitated HLP(UHLP), given the difficulty in computation that comes with capacity constraints. Particularly, together with incomplete hub networks, capacity constraints have shown to be highly intractable. We develop a novel, efficient Benders decomposition algorithm to solve the CHLP with incomplete hub networks. In order to explore the impact of capacity constraints on hubs and backbone arcs, the CAB dataset is used as a case study. In addition, we compare the performance of our improved algorithm to the classical one. We find that capacity constraints on hubs and backbone links tend to render a robust network with more fully connected hub node pairs and flexible linking structure. In addition, the computation time is significantly reduced, up to one order of magnitude, compared with the state-of-the-art. We believe that our work lays the foundation for solving more realistic hub location problems.\",\n \"Title: Fog-Based Two-Phase Event Monitoring and Data Gathering in Vehicular Sensor Networks.\\nYear: 2018\\n\\nAbstract: Vehicular nodes are equipped with more and more sensing units, and a large amount of sensing data is generated. Recently, more and more research considers cooperative urban sensing as the heart of intelligent and green city traffic management. The key components of the platform will be a combination of a pervasive vehicular sensing system, as well as a central control and analysis system, where data-gathering is a fundamental component. However, the data-gathering and monitoring are also challenging issues in vehicular sensor networks because of the large amount of data and the dynamic nature of the network. In this paper, we propose an efficient continuous event-monitoring and data-gathering framework based on fog nodes in vehicular sensor networks. A fog-based two-level threshold strategy is adopted to suppress unnecessary data upload and transmissions. In the monitoring phase, nodes sense the environment in low cost sensing mode and generate sensed data. When the probability of the event is high and exceeds some threshold, nodes transfer to the event-checking phase, and some nodes would be selected to transfer to the deep sensing mode to generate more accurate data of the environment. Furthermore, it adaptively adjusts the threshold to upload a suitable amount of data for decision making, while at the same time suppressing unnecessary message transmissions. Simulation results showed that the proposed scheme could reduce more than 84 percent of the data transmissions compared with other existing algorithms, while it detects the events and gathers the event data.\",\n \"Title: Anti-jamming transmission in UAV communication networks: A Stackelberg game approach.\\nYear: 2017\\n\\nAbstract: We investigate the anti-jamming problem in unmanned aerial vehicles (UAV) communication networks, in which the mutual interference among UAVs is considered. A Stackelberg game approach is proposed to solve this problem. The smart jammer who has the privilege over multiple users acts first as the leader of the game, while the users act as the followers after knowing the strategy of the smart jammer. The optimal transmission power of users and smart jammer are derived, and the influence of transmission cost on the users and the smart jammer are shown in the simulation results. The existence as well as the uniqueness of the Stackelberg equlibrium (SE) have been proved as well.\",\n \"Title: A One-Leader Multi-Follower Bayesian-Stackelberg Game for Anti-Jamming Transmission in UAV Communication Networks.\\nYear: 2018\\n\\nAbstract: This paper focuses on the anti-jamming transmission problem in unmanned aerial vehicle (UAV) communication networks. Considering the incomplete information constraint and the co-channel mutual interference, a Bayesian Stackelberg game is proposed to formulate the competitive relations between UAVs (users) and the jammer. Specifically, the jammer acts as the leader, whereas users act as followers of the proposed game. Based on their utility functions, the jammer and users select their optimal power control strategies respectively. In addition, the observation error is also investigated in this paper. Due to the incomplete information constraint and the existence of co-channel mutual interference, it is challenging to obtain Stackelberg equilibrium (SE) of the proposed game. Thus, a sub-gradient based Bayesian Stackelberg iterative algorithm is proposed to obtain SE. Finally, simulations are conducted to demonstrate the performance of the proposed algorithm, and the impact of incomplete information and observation error on users' utilities are also presented.\",\n \"Title: A NUMA-Aware Provably-Efficient Task-Parallel Platform Based on the Work-First Principle\\nYear: 2018\\n\\nAbstract: Task parallelism is designed to simplify the task of parallel programming. When executing a task parallel program on modern NUMA architectures, it can fail to scale due to the phenomenon called work inflation, where the overall processing time that multiple cores spend on doing useful work is higher compared to the time required to do the same amount of work on one core, due to effects experienced only during parallel executions such as additional cache misses, remote memory accesses, and memory bandwidth issues.One can mitigate work inflation by co-locating the computation with its data, but this is nontrivial to do with task parallel programs. First, by design, the scheduling for task parallel programs is automated, giving the user little control over where the computation is performed. Second, the platforms tend to employ work stealing, which provides strong theoretical guarantees, but its randomized protocol for load balancing does not discern between work items that are far away versus ones that are closer.In this work, we propose NUMA-WS, a NUMA-aware task parallel platform engineered based on the work-first principle. By abiding by the work-first principle, we are able to obtain a platform that is work efficient, provides the same theoretical guarantees as a classic work stealing scheduler, and mitigates work inflation. We have extended Cilk Plus runtime system to implemented NUMA-WS. Empirical results indicate that the NUMA-WS is work efficient and can provide better scalability by mitigating work inflation.\",\n \"Title: Power Attack and Protected Implementation on Lightweight Block Cipher SKINNY\\nYear: 2018\\n\\nAbstract: SKINNY is a new lightweight tweakable block cipher family, which can compete to other lightweight cipher in terms of hardware or software implementations. While its theoretical security has been widely studied, little effort has been made to analyze its implementation security such as side-channel attacks protection. In this paper, we first give correlation power attack and its experiment on SKINNY. Then, a masking scheme for software SKINNY is proposed against side-channel attacks. Its implementation shows that the protected SKINNY only costs 8.42%, 183.27%, and 90.85% of extra code, time, and RAM, respectively.\",\n \"Title: Collaborative Route Plan For Parking Sites Selection In Bike-Sharing Systems\\nYear: 2018\\n\\nAbstract: In order to alleviate the traffic congestion caused by the bike-sharing system, the bicycles should be parked in designated parking sites, particularly around the hot scenic spots. A proper route, which guides the cyclers to select a vacant place among the sites to park the bike, is required. In this paper, the Expected Travel Distance (KID) and the Probability of Successful Parking (PSP) are formulated to evaluate the routes, which will guide the users to travel all the parking sites. We exploit the Poisson process to model the increment of the bicycle number in the parking site and construct the travel tree for the route plan problem. To provide a proper route, we propose the GOR algorithm and the F-M method based on the travel tree. Through extensive simulations, our algorithms are compared with TSP in terms of ETD, PSP and the execution time.\",\n \"Title: Plasmonic Sensing Characteristics of Gold Nanorods with Large Aspect Ratios.\\nYear: 2018\\n\\nAbstract: Plasmonic gold nanorods play important roles in nowadays state-of-the-art plasmonic sensing techniques. Most of the previous studies and applications focused on gold nanorods with relatively small aspect ratios, where the plasmon wavelengths are smaller than 900 nm. Gold nanorods with large aspect ratios are predicted to exhibit high refractive-index sensitivity (Langmir 2008, 24, 5233-5237), which therefore should be promising for the development of high-performance plasmonic chemical- and bio-sensors. In this study, we developed gold nanorods with aspect ratios over 7.9, which exhibit plasmon resonances around 1064 nm. The refractive index (RI) sensitivity of these nanorods have been evaluated by varying their dielectric environment, whereby a sensitivity as high as 473 nm/RIU (refractive index unit) can be obtained. Furthermore, we have demonstrated the large-aspect-ratio nanorods as efficient substrate for surface enhanced Raman spectroscopy (SERS), where an enhancement factor (EF) as high as 9.47 x 10(8) was measured using 4-methylbenzenethiol (4-MBT) as probe molecule. Finally, a type of flexible SERS substrate is developed by conjugating the gold nanorods with the polystyrene (PS) polymer. The results obtained in our study can benefit the development of plasmonic sensing techniques utilized in the near-infrared spectral region.\",\n \"Title: A stochastic multi-channel revenue management model with time-dependent demand.\\nYear: 2018\\n\\nAbstract: •This paper examines the firm's optimal channel control strategy with combining its revenue management decision.•A multi-period multi-channel continuous-time model with time-dependent arrival rates has been proposed.•Using the Maximum Principle, the optimal channel control rules are found and a threshold channel control policy is proposed.\",\n \"Title: Proactive work stealing for futures.\\nYear: 2019\\n\\nAbstract: The use of futures provides a flexible way to express parallelism and can generate arbitrary dependences among parallel subcomputations. The additional flexibility that futures provide comes with a cost, however. When scheduled using classic work stealing, a program with futures, compared to a program that uses only fork-join parallelism, can incur a much higher number of \\\"deviations,\\\" a metric for evaluating the performance of parallel executions. All prior works assume a parsimonious work-stealing scheduler, however, where a worker thread (surrogate of a processor) steals work only when its local deque becomes empty.\\n\\nIn this work, we investigate an alternative scheduling approach, called ProWS, where the workers perform proactive work stealing when handling future operations. We show that ProWS, for programs that use futures, can provide provably efficient execution time and equal or better bounds on the number of deviations compared to classic parsimonious work stealing. Given a computation with T1 work and T∞ span, ProWS executes the computation on P processors in expected time O(T1/P + T∞ lg P), with an additional lg P overhead on the span term compared to the parsimonious variant. For structured use of futures, where each future is single touch with no race on the future handle, the algorithm incurs deviations, matching that of the parsimonious variant. For general use of futures, the algorithm incurs O(mkT∞ + PT∞ lg P) deviations, where mk is the maximum number of future touches that are logically parallel. Compared to the bound for the parsimonious variant, O(kT∞ + PT∞), with k being the total number of touches in the entire computation, this bound is better assuming mk = Ω(P lg P) and is smaller than k, which holds true for all the benchmarks we examined.\",\n \"Title: Inventory centralization with risk-averse newsvendors.\\nYear: 2018\\n\\nAbstract: In the paper, we study the inventory centralization problem with risk-averse newsvendors using cooperative game theory. Pareto-optimality and collective rationality conditions are adopted to characterize the stable profit allocations among coalition members. Pareto-optimal profit allocation rules are derived for exponential and power utilities while the necessary and sufficient conditions are shown for stable profit allocations. We also show that the game model has a nonempty core when the exponential and power utilities are adopted to describe the risk-averse behavior.\",\n \"Title: Deep Review Sharing\\nYear: 2019\\n\\nAbstract: Review-Based Software Improvement (RBSI for short) has drawn increasing research attentions in recent years. Relevant efforts focus on how to leverage the underlying information within reviews to obtain a better guidance for further updating. However, few efforts consider the Projects Without sufficient Reviews (PWR for short). Actually, PWR dominates the software projects, and the lack of PWR-based RBSI research severely blocks the improvement of certain software. In this paper, we make the first attempt to pave the road. Our goal is to establish a generic framework for sharing suitable and informative reviews to arbitrary PWR. To achieve this goal, we exploit techniques of code clone detection and review ranking. In order to improve the sharing precision, we introduce Convolutional Neural Network (CNN) into our clone detection, and design a novel CNN based clone searching module for our sharing system. Meanwhile, we adopt a heuristic filtering strategy to reduce the sharing time cost. We implement a prototype review sharing system RSharer and collect 72,440 code-review pairs as our ground knowledge. Empirical experiments on hundreds of real code fragments verify the effectiveness of RSharer. RSharer also achieves positive response and evaluation by expert developers.\",\n \"Title: High Temporal Resolution Monitoring of Suspended Matter Changes from GOCI Measurements in Lake Taihu.\\nYear: 2019\\n\\nAbstract: The Tiaoxi River is the main source of water for Lake Taihu and can result in plumes in the lake after heavy precipitation events. These plumes have played a crucial role in the water quality changes within the lake. High temporal resolution GOCI (Geostationary Ocean Color Imager) data were used to study the spatial distribution of the total suspended matter concentration in Lake Taihu after heavy precipitation events in the Tiaoxi River Basin via an empirical model. The plumes were analyzed after two heavy precipitation events in 2011 and 2013 using 16 GOCI images, which indicated that the Tiaoxi River had a great influence on the spatial distributions of total suspended matter and algal blooms. It was concluded that the main factors affecting the plumes in the Tiaoxi River were precipitation intensity, runoff, and total suspended matter concentration. Human activity, such as sand excavation also played a crucial role in sediment discharge. The results of this study demonstrate that the visualization of GOCI data makes it possible to use remote sensing technology to continuously monitor an inland water environment on an hourly scale, which is of great significance for studying the diffusion and evolution of river plumes.\",\n \"Title: LISA: a MATLAB package for Longitudinal Image Sequence Analysis.\\nYear: 2019\\n\\nAbstract: Large sequences of images (or movies) can now be obtained on an unprecedented scale, which poses fundamental challenges to the existing image analysis techniques. The challenges include heterogeneity, (automatic) alignment, multiple comparisons, potential artifacts, and hidden noises. This paper introduces our MATLAB package, Longitudinal Image Sequence Analysis (LISA), as a one-stop ensemble of image processing and analysis tool for comparing a general class of images from either different times, sessions, or subjects. Given two contrasting sequences of images, the image processing in LISA starts with selecting a region of interest in two representative images, followed by automatic or manual segmentation and registration. Automatic segmentation de-noises an image using a mixture of Gaussian distributions of the pixel intensity values, while manual segmentation applies a user-chosen intensity cut-off value to filter out noises. Automatic registration aligns the contrasting images based on a mid-line regression whereas manual registration lines up the images along a reference line formed by two user-selected points. The processed images are then rendered for simultaneous statistical comparisons to generate D, S, T, and P-maps. The D map represents a curated difference of contrasting images, the S map is the non-parametrically smoothed differences, the T map presents the variance-adjusted, smoothed differences, and the P-map provides multiplicity-controlled p-values. These maps reveal the regions with significant differences due to either longitudinal, subject-specific, or treatment changes. A user can skip the image processing step to dive directly into the statistical analysis step if the images have already been processed. Hence, LISA offers flexibility in applying other image pre-processing tools. LISA also has a parallel computing option for high definition images.\",\n \"Title: Privacy-aware query processing in vehicular ad-hoc networks\\nYear: 2019\\n\\nAbstract: Recently there is a research trend to integrate the cloud and the vehicular ad-hoc networks to enhance each other on the cooperative urban sensing applications. However, it remains a challenging problem on how to forward queries to search the results and then to route back the query results, as the vehicular nodes dynamically move on the road. Also, the dark side of vehicular cloud is often ignored. Getting the owner’s identity or locations of a given vehicle, or getting the queries submitted by vehicles would put the data privacy at risk. In this paper we propose a privacy preserving query processing scheme for vehicular sensor networks. The scheme consists of two phases: 1) at the index mapping phase, sensed data are stored locally at road side units (RSU), and a global index is maintained at the cloud; 2) at the query processing phase, queries are transformed based on a mapping function, and then are routed to the cloud. The cloud computes the set of RSUs that have the query result based on the mapping index, and then directs the query to the RSUs. Then the result forwarding is transformed into a query result forwarding problem at the RSU, where the data of query results are routed back at their best paths either through the 4G channel or through the DSRC (Dedicated Short Range Communication) channel. Also, the query results are encrypted and diffused to a set of RSUs that the query requester would travel along, so the requester could fetch the results before the query is outdated. Extensive experiments demonstrate the effectiveness of the proposed algorithm in vehicular sensor networks. The ratio of successful query delivery is higher than existing query schemes, while at the same time preserving the privacy of query requesters and the data owner in vehicular sensor networks.\",\n \"Title: Simulation And Assessment Of The Capabilities Of Orbita Hyperspectral (Ohs) Imagery For Remotely Monitoring Chlorophyll-A In Eutrophic Plateau Lakes\\nYear: 2021\\n\\nAbstract: The chlorophyll-a (Chl-a) concentration of eutrophic lakes fluctuates significantly due to the disturbance of wind and anthropogenic activities on the water body. Consequently, estimation of the Chl-a concentration has become an immense challenge. Due to urgent demand and rapid development in high-resolution earth observation systems, it has become crucial to assess hyperspectral satellite imagery capabilities on inland water monitoring. The Orbita hyperspectral (OHS) satellite is the latest hyperspectral sensor with both high spectral and spatial resolution (2.5 nm and 10 m, respectively), which could provide great potential for remotely estimating the concentration of Chl-a for inland waters. However, there are still some deficiencies that are mainly manifested in the Chl-a concentration remote sensing retrieval model assessment and accuracy validation, as well as signal-to-noise ratio (SNR) estimation of OHS imagery for inland waters. Therefore, the radiometric performance of OHS imagery for water quality monitoring is evaluated in this study by comparing different atmospheric correction models and the SNR with several remote sensing images. Several crucial findings can be drawn: (1) the three-band model ((1/B15-1/B17)B19) developed by OHS imagery is most suitable for estimating the Chl-a concentration in Dianchi Lake, with the root-mean-square error (RMSE) and the mean absolute percentage error (MAPE) of 15.55 mu g/L and 16.31%, respectively; (2) the applicability of the FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes) atmospheric correction model for OHS imagery in a eutrophic plateau lake (Dianchi Lake) was better than the 6S (Second Simulation of Satellite Signal in the Solar Spectrum) model, and QUAC (Quick Atmospheric Correction) model, as well as the dark pixel method; (3) the SNR of the OHS imagery was similar to that of Hyperion imagery and was significantly higher than SNR of the HSI imagery; (4) the spatial resolution showed slight influence on the SNR of the OHS imagery. The results show that OHS imagery could be applied to remote sensing retrieval of Chl-a in eutrophic plateau lakes and presents a new tool for dynamic hyperspectral monitoring of water quality.\",\n \"Title: Evo-ViT: Slow-Fast Token Evolution for Dynamic Vision Transformer.\\nYear: 2022\\n\\nAbstract: Vision transformers (ViTs) have recently received explosive popularity, but the huge computational cost is still a severe issue. Since the computation complexity of ViT is quadratic with respect to the input sequence length, a mainstream paradigm for computation reduction is to reduce the number of tokens. Existing designs include structured spatial compression that uses a progressive shrinking pyramid to reduce the computations of large feature maps, and unstructured token pruning that dynamically drops redundant tokens. However, the limitation of existing token pruning lies in two folds: 1) the incomplete spatial structure caused by pruning is not compatible with structured spatial compression that is commonly used in modern deep-narrow transformers; 2) it usually requires a time-consuming pre-training procedure. To tackle the limitations and expand the applicable scenario of token pruning, we present Evo-ViT, a self-motivated slow-fast token evolution approach for vision transformers. Specifically, we conduct unstructured instance-wise token selection by taking advantage of the simple and effective global class attention that is native to vision transformers. Then, we propose to update the selected informative tokens and uninformative tokens with different computation paths, namely, slow-fast updating. Since slow-fast updating mechanism maintains the spatial structure and information flow, Evo-ViT can accelerate vanilla transformers of both flat and deep-narrow structures from the very beginning of the training process. Experimental results demonstrate that our method significantly reduces the computational cost of vision transformers while maintaining comparable performance on image classification. For example, our method accelerates DeiT-S by over 60% throughput while only sacrificing 0.4% top-1 accuracy on ImageNet-1K, outperforming current token pruning methods on both accuracy and efficiency.\",\n \"Title: Gis Partial Discharge Pattern Recognition Based On A Novel Convolutional Neural Networks And Long Short-Term Memory\\nYear: 2021\\n\\nAbstract: Distinguishing the types of partial discharge (PD) caused by different insulation defects in gas-insulated switchgear (GIS) is a great challenge in the power industry, and improving the recognition accuracy of the relevant models is one of the key problems. In this paper, a convolutional neural network and long short-term memory (CNN-LSTM) model is proposed, which can effectively extract and utilize the spatiotemporal characteristics of PD input signals. First, the spatial characteristics of higher-level PD signals can be obtained through the CNN network, but because CNN is a deep feedforward neural network, it does not have the ability to process time-series data. The PD voltage signal is related to the time dimension, so LSTM saves and analyzes the previous voltage signal information, realizes the modeling of the time dependence of the data, and improves the accuracy of the PD signal pattern recognition. Finally, the pattern recognition results based on CNN-LSTM are given and compared with those based on other traditional analysis methods. The results show that the pattern recognition rate of this method is the highest, with an average of 97.9%, and its overall accuracy is better than that of other traditional analysis methods. The CNN-LSTM model provides a reliable reference for GIS PD diagnosis.\",\n \"Title: CEBD: Contact-Evidence-Driven Blackhole Detection Based on Machine Learning in OppNets\\nYear: 2021\\n\\nAbstract: Blackhole detection in the opportunistic networks offers an effective means to mitigate the routing performance degradation but faces many challenges from corrupted nodes due to their collusion behaviors. Most existing effort in the literature focuses on the blackhole feature extraction from the message exchange. However, the decay effect of features and the forged features from the corrupted node...\",\n \"Title: Better Late Than Never: GAN-Enhanced Dynamic Anti-Jamming Spectrum Access With Incomplete Sensing Information\\nYear: 2021\\n\\nAbstract: This letter studies the problem of anti-jamming spectrum access in dynamic and unknown environments with incomplete spectrum sensing information. Most existing studies were based on the assumption that users have perfect spectrum information, thus they worked poorly with incomplete sensing information. To overcome the shortcoming, we present a robust intelligent anti-jamming spectrum access scheme which includes spectrum sensing, completion, learning and access. To complete the missing spectrum data, we design a generative adversarial network (GAN) based spectrum completion network. Based on deep reinforcement learning (DRL), a channel selection network is introduced to choose effective anti-jamming channel access policy. Simulation results show that the proposed approach is able to avoid complex jamming attacks effectively and outperforms conventional DRL-based approach with incomplete spectrum information.\",\n \"Title: Efficient Parallel Determinacy Race Detection for Structured Futures\\nYear: 2021\\n\\nAbstract: ABSTRACTIn task-parallel code, a determinancy race occurs when two logically parallel instructions access the same memory location in a conflicting way. A determinacy race tends to be a bug as it leads to non-deterministic program behaviors. Researchers have studied algorithms for detecting determinacy races in task-parallel code, with most prior work focuses on computations with nice structural properties (e.g., fork-join or pipeline parallelism). For such computations, one can devise provably efficient algorithms with constant overhead, leading to a asymptotically optimal running time --- O(T_1 / P + T_∞) on P cores for a computation with T_1 work and T_∞ span. More recently, researchers have begun to address the problem of race detecting computations with less structural properties, such as ones that arise from the use of futures. Due to the lack of structural properties, the race detection algorithm incurs higher overhead. % Given a computation with work T_1 and span T_∞, the state-of-the-art parallel algorithm for race detecting programs with futures runs in time O((T_1 łgk + k^2) / P + T_∞(łg k + łgr łgk )) on P cores (Xu ηl, 2020), where k is the total number of futures used, k is the maximum number of future operations per \\\"future task,'' and r is the maximum number of readers between two consecutive writes to a given memory location. Interestingly, it has been shown that when one imposes certain restrictions on the use of futures, referred to as the structured futures, although the restrictions do not entirely eliminate arbitrary dependences among subcomputations, one can race detect such programs more efficiently than that for programs with general futures (i.e., no restrictions). The improved efficiency has only been demonstrated for a sequential algorithm (Utterback ηl, 2019) that race detects while executing the computation sequentially, however. The algorithm requires sequential execution, because the correctness of the algorithm relies on updating the necessary data structures while traversing the computation dag in a specific order. An interesting question remains, whether a parallel algorithm exists for race detecting programs with structured future that achieves better execution time compared to that designed for general futures. This work attempts to answer this question. We propose a parallel algorithm designed to race detect structured futures. By exploiting the restrictions imposed by structured futures, the proposed algorithm allows for a constant-time query while keeping fewer previous accessors around to provide the same correctness guarantees as prior work. Our algorithm runs in time O((T_1 + k^2)/P + T_∞ łg k) on P cores. We have also implemented and empirically evaluated the proposed algorithm. When compared to the state-of-the-art sequential algorithm designed for structured futures, although our algorithm has a longer one-core execution time, its absolute running time wins out when running on two cores or more. When compared to the state-of-the-art parallel algorithm designed for general futures, it indeed incurs lower overhead and performs better.\",\n \"Title: Efficient Access History for Race Detection\\nYear: 2021\\n\\nAbstract: ABSTRACTWhile there has been extensive research on race-detection algorithms for task-parallel programs, most of this research has focused on optimizing a particular component, namely, reachability analysis, which checks whether two instructions are logically in parallel. Little attention has been paid to the other important component, the access history, which stores all memory locations previous instructions have accessed. In theory, the access-history component adds no asymptotic overhead; however, in practice, it is often the most expensive component of race detection since it is queried and (possibly) updated at each memory access. We optimize this component based on the observation that, typically, strands within parallel programs access contiguous blocks of memory. Therefore, instead of maintaining the access history at the granularity of individual memory locations, we maintain it at the granularity of these (varying size) intervals. To enable this access history, we propose (1) compiler and runtime mechanisms that allow us to efficiently collect these intervals and (2) a tree-based access-history data structure that allows updates and queries at interval granularity. The resulting tool can race-detect fork-join code with amortized constant overhead, assuming the number of intervals is small compared to the total work of the computation.\",\n \"Title: Tree Extraction From Airborne Laser Scanning Data In Urban Areas\\nYear: 2021\\n\\nAbstract: Tree information in urban areas plays a significant role in many fields of study, such as ecology and environmental management. Airborne LiDAR scanning (ALS) excels at the fast and efficient acquisition of spatial information in urban-scale areas. Tree extraction from ALS data is an essential part of tree structural studies. Current raster-based methods that use canopy height models (CHMs) suffer from the loss of 3D structure information, whereas the existing point-based methods are non-robust in complex environments. Aiming at making full use of the canopy's 3D structure information that is provided by point cloud data, and ensuring the method's suitability in complex scenes, this paper proposes a new point-based method for tree extraction that is based on 3D morphological features. Considering the elevation deviations of the ALS data, we propose a neighborhood search method to filter out the ground and flat-roof points. A coarse extraction method, combining planar projection with a point density-filtering algorithm is applied to filter out distracting objects, such as utility poles and cars. After that, a Euclidean cluster extraction (ECE) algorithm is used as an optimization strategy for coarse extraction. In order to verify the robustness and accuracy of the method, airborne LiDAR data from Zhangye, Gansu, China and unmanned aircraft vehicle (UAV) LiDAR data from Xinyang, Henan, China were tested in this study. The experimental results demonstrated that our method was suitable for extracting trees in complex urban scenes with either high or low point densities. The extraction accuracy obtained for the airborne LiDAR data and UAV LiDAR data were 99.4% and 99.2%, respectively. In addition, a further study found that the aberrant vertical structure of the artificially pruned canopy was the main cause of the error. Our method achieved desirable results in different scenes, with only one adjustable parameter, making it an easy-to-use method for urban area studies.\",\n \"Title: Fairness Maximization Among Offline Agents in Online-Matching Markets\\nYear: 2021\\n\\nAbstract: Matching markets involve heterogeneous agents (typically from two parties) who are paired for mutual benefit. During the last decade, matching markets have emerged and grown rapidly through the medium of the Internet. They have evolved into a new format, called Online Matching Markets (OMMs), with examples ranging from crowdsourcing to online recommendations to ridesharing. There are two features distinguishing OMMs from traditional matching markets. One is the dynamic arrival of one side of the market: we refer to these as online agents while the rest are offline agents. Examples of online and offline agents include keywords (online) and sponsors (offline) in Google Advertising; workers (online) and tasks (offline) in Amazon Mechanical Turk (AMT); riders (online) and drivers (offline when restricted to a short time window) in ridesharing. The second distinguishing feature of OMMs is the real-time decision-making element. However, studies have shown that the algorithms making decisions in these OMMs leave disparities in the match rates of offline agents. For example, tasks in neighborhoods of low socioeconomic status rarely get matched to gig workers, and drivers of certain races/genders get discriminated against in matchmaking. In this paper, we propose online matching algorithms which optimize for either individual or group-level fairness among offline agents in OMMs. We present two linear-programming (LP) based sampling algorithms, which achieve online competitive ratios at least 0.725 for individual fairness maximization (IFM) and 0.719 for group fairness maximization (GFM), respectively. We conduct extensive numerical experiments and results show that our boosted version of sampling algorithms are not only conceptually easy to implement but also highly effective in practical instances of fairness-maximization-related models.\",\n \"Title: FAMGAN: Fine-grained AUs Modulation based Generative Adversarial Network for Micro-Expression Generation\\nYear: 2021\\n\\nAbstract: ABSTRACTMicro-expressions (MEs) are significant and effective clues to reveal the true feelings and emotions of human beings, and thus MEs analysis is widely used in different fields such as medical diagnosis, interrogation and security. However, it is extremely difficult to elicit and label MEs, resulting in a lack of sufficient MEs data for MEs analysis. To address this challenge and inspired by the current face generation technology, in this paper we introduce Generative Adversarial Network based on fine-grained Action Units (AUs) modulation to generate MEs sequence (FAMGAN). Specifically, after comprehensively analyzing the factors that lead to inaccurate AU values detection, we performed fine-grained AUs modulation, which includes carefully eliminating the various noises and dealing with the asymmetry of AUs intensity. Additionally, we incorporate super-resolution into our model to enhance the quality of the generated images. Through experiments, we show that the system achieves very competitive results on the Micro-Expression Grand Challenge (MEGC2021).\",\n \"Title: TSOR: Thompson Sampling-Based Opportunistic Routing\\nYear: 2021\\n\\nAbstract: Routing is a fundamental problem and has been extensively studied in various networks. However, in highly dynamic networks (e.g., wireless ad hoc networks), nodes have limited transmission opportunities due to high mobility, noise and interference, where traditional routing is often not the best approach. Opportunistic routing (OR), on the other hand, can effectively minimize the ...\",\n \"Title: RFNet - Recurrent Forward Network for Dense Point Cloud Completion.\\nYear: 2021\\n\\nAbstract: Point cloud completion is an interesting and challenging task in 3D vision, aiming to recover complete shapes from sparse and incomplete point clouds. Existing learning-based methods often require vast computation cost to achieve excellent performance, which limits their practical applications. In this paper, we propose a novel Recurrent Forward Network (RFNet), which is composed of three modules: Recurrent Feature Extraction (RFE), Forward Dense Completion (FDC) and Raw Shape Protection (RSP). The RFE extracts multiple global features from the incomplete point clouds for different recurrent levels, and the FDC generates point clouds in a coarse-to-fine pipeline. The RSP introduces details from the original incomplete models to refine the completion results. Besides, we propose a Sampling Chamfer Distance to better capture the shapes of models and a new Balanced Expansion Constraint to restrict the expansion distances from coarse to fine. According to the experiments on ShapeNet and KITTI, our network can achieve the state-of-the-art with lower memory cost and faster convergence.\",\n \"Title: Energy-Efficient Channel Access and Data Offloading Against Dynamic Jamming Attacks\\nYear: 2021\\n\\nAbstract: Multi-access edge computing (MEC) system is developing to take advantage of the adjacent computation devices to reach better performance for IoT networks, and has to fight against malicious jamming attacks and heavy co-channel interference. To address this issue, this paper investigates the energy-efficient MEC optimization problem in a jamming environment where the attack activities of the jammer...\",\n \"Title: Equity Promotion in Online Resource Allocation.\\nYear: 2022\\n\\nAbstract: We consider online resource allocation under a typical non-profit setting, where limited or even scarce resources are administered by a not-for-profit organization like a government. We focus on the internal-equity by assuming that arriving requesters are homogeneous in terms of their external factors like demands but heterogeneous for their internal attributes like demographics. Specifically, we associate each arriving requester with one or several groups based on their demographics (i.e., race, gender, and age), and we aim to design an equitable distributing strategy such that every group of requesters can receive a fair share of resources proportional to a preset target ratio. We present two LP-based sampling algorithms and investigate them both theoretically (in terms of competitive-ratio analysis) and experimentally based on real COVID-19 vaccination data maintained by the Minnesota Department of Health. Both theoretical and numerical results show that our LP-based sampling strategies can effectively promote equity, especially when the arrival population is disproportionately represented, as observed in the early stage of the COVID-19 vaccine rollout.\",\n \"Title: A multi-agent reinforcement learning anti-jamming method with partially overlapping channels\\nYear: 2021\\n\\nAbstract: This paper investigates the problem of multi-user anti-jamming channel access with partially overlapping channels (POC). Compared with traditional anti-jamming systems that use non-overlapping channels, POC improve the spectral efficiency. However, the partial overlap of channels also brings more serious interference. For this, physical distance and channel separation on the interference intensity under partially overlapping channels are first considered and the malicious jamming and interference among users are formulated as a hierarchical binary model. Secondly, to cope with multi-user decisions under dynamic jamming conditions, the Markov game framework is adopted to analyse the problem. Thirdly, a multi-user collaborative anti-jamming channel selection algorithm based on reinforcement learning is proposed as well as the optimal anti-jamming strategy can be obtained. Finally, the simulation results validate that the proposed algorithm helps users cope with jamming and eliminate mutual interference. Compared with the non-overlapping channel access scheme, the POC access scheme achieves higher network throughput.\",\n \"Title: Primary-User-Friendly Dynamic Spectrum Anti-Jamming Access: A GAN-Enhanced Deep Reinforcement Learning Approach\\nYear: 2022\\n\\nAbstract: This letter studies the problem of deep reinforcement learning (DRL)-based dynamic spectrum anti-jamming access in overlay cognitive radio networks. To prevent secondary user (SU) from interfering with primary user (PU) and being jammed by jammer, we propose a PU-friendly dynamic spectrum anti-jamming access scheme. First, a generative adversarial network (GAN)-based virtual environment is proposed to simulate spectrum environment. Then, a DRL-based channel decision network (CDN) is trained to learn the optimal spectrum access policy in the virtual environment. Finally, SU accesses spectrum environment under the guidance of the trained CDN. Simulation results show that the proposed scheme is able to elude both PU signals and jamming completely and converges much faster than the scheme that trains the CDN in spectrum environment from scratch.\",\n \"Title: Play it by Ear: Context-Aware Distributed Coordinated Anti-Jamming Channel Access\\nYear: 2021\\n\\nAbstract: This paper investigates the anti-jamming problems in wireless communication networks. In these networks consisted of multiple devices (users), there exist two critical problems. On the one hand, users with various transmission requirements should coordinate their channel selection strategies distributedly to avoid spectrum conflicts and satisfy transmission demands. On the other hand, they also need to fully consider how to eliminate the effects of malicious attacks. To cope with the internal coordination and external confrontation challenges and accommodate the dynamic changing jamming attacks, a context-aware distributed coordinated anti-jamming channel access mechanism is proposed, which means for different cases of jamming attacks, different access strategies are adopted. In detail, to reflect the heterogeneous communication demands of users, the transmission satisfaction function is firstly introduced. Then, the multi-user anti-jamming scenario is modeled as a context-aware multi-pattern dynamic anti-jamming game, which can be decomposed into two sub-games. Here, for the case that the control channel is available, a local altruistic sub-game is introduced. While for the case that the control channel has been jammed, an anti-jamming congestion sub-game is designed. Besides, the existence of Nash Equilibriums is demonstrated. To obtain NEs, a context-aware distributed channel access (CDCA) algorithm is designed. Through game-theoretic analysis and distributed learning, global transmission satisfaction can be improved under the dynamic jamming environment. Furthermore, the fairness of the network can also be guaranteed.\",\n \"Title: Optimized Large-Scale Road Sensing Through Crowdsourced Vehicles\\nYear: 2022\\n\\nAbstract: Modern vehicles are gradually becoming powerful mobile sensing, communication, computing and storage platforms, which bring about the concept of vehicular urban sensing that leverages sensor nodes as an effective and affordable solution for large-scale and fine-grained sensing. And there is a trend to combine the vehicular sensing and outsourcing technologies to solve the large-scale urban road se...\",\n \"Title: Proceed From Known to Unknown: Jamming Pattern Recognition Under Open-Set Setting\\nYear: 2022\\n\\nAbstract: In this letter, we study the problem of jamming pattern recognition (JPR) when some patterns have no training samples. Existing works were designed for recognition of known jamming patterns only, hence they failed to deal with unknown jamming patterns. To address this challenge, a zero-shot learning (ZSL) based JPR scheme is proposed. Firstly, a supervised training process is introduced to learn t...\",\n \"Title: Joint flight scheduling and task allocation for secure data collection in UAV-aided IoTs\\nYear: 2022\\n\\nAbstract: With the flexible mobility and deployment, Unmanned Aerial Vehicles (UAVs) have created a new dimension to provide data collection services for a large number of distributed wireless sensory devices. Unfortunately, the broadcast nature of wireless channels make it hard to guarantee the security of data transmission in Internet of Things (IoTs). In this paper, focusing on the scenario where potential eavesdroppers intend to intercept the data uploading of legitimate nodes, we take the advantages of the UAV technology and the physical-layer security approach to study the Secure Data Collection Problem (SDCP). We first explore the flight scheduling and task allocation, that is, determining which areas to be visited and who to be served by UAVs, to establish favorable communication channels. Then we set up the utility function with secrecy rates and non-negative budget constraints. Due to the coupling between the UAV scheduling and task allocation optimization variables in the SDCP, we construct a surrogate function to achieve decoupling and reformulate SDCP into the SDCP-m problem, which is analyzed and proved to be a nonnegative monotone submodular function subject to a general constraint. Finally, an efficient Cost-Benefit Greedy (CBG) algorithm, which is theoretically analyzed to seek the quantitative value of approximation ratio, is proposed. The simulation results show that the CBG algorithm not only outperforms benchmark algorithms in terms of the average secrecy rate and the iteration number, but also generates a nearly optimal trajectory.\",\n \"Title: Joint channel and power optimisation for multi-user anti-jamming communications: A dual mode Q-learning approach\\nYear: 2022\\n\\nAbstract: In view of the anti-tracking-jamming problem, traditional online learning methods usually cannot analyse the jamming behaviour, and find an effective way to prevent the jamming attacks. To cope with these challenges, a novel communication/deception dual mode mechanism is proposed in this paper. Deception users are selected to send high-power signal for jamming attraction, and form collaborative relationships with communication users. The corresponding collaborative anti-jamming model is then constructed as a Markov game to analyse the multi-agent decision. Based on that, a joint channel and power optimisation for multi-user anti-jamming communications based on dual mode Q-learning scheme is proposed. Compared with two traditional online learning algorithms, the proposed DCAJ-QL algorithm effectively achieves 146.5% and 80.4% higher maximum communication rate under tracking jamming conditions, and achieves 40.7% and 53.6% higher maximum communication rate under fixed jamming conditions.\",\n \"Title: Providers-Clients-Robots: Framework for spatial-semantic planning for shared understanding in human-robot interaction.\\nYear: 2022\\n\\nAbstract: This paper develops a novel framework called Providers-Clients-Robots (PCR), applicable to socially assistive robots that support research on shared understanding in human-robot interactions. Providers, Clients, and Robots share an actionable and intuitive representation of the environment to create plans that best satisfy the combined needs of all parties. The plans are formed via interaction between the Client and the Robot based on a previously built multi-modal navigation graph. The explainable environmental representation in the form of a navigation graph is constructed collaboratively between Providers and Robots prior to interaction with Clients. We develop a realization of the proposed framework to create a spatial-semantic representation of an indoor environment autonomously. Moreover, we develop a planner that takes in constraints from Providers and Clients of the establishment and dynamically plans a sequence of visits to each area of interest. Evaluations show that the proposed realization of the PCR framework can successfully make plans while satisfying the specified time budget and sequence constraints and outperforming the greedy baseline.\",\n \"Title: A Novel Method for Pattern Recognition of GIS Partial Discharge via Multi-Information Ensemble Learning\\nYear: 2022\\n\\nAbstract: Partial discharge (PD) is the main feature that effectively reflects the internal insulation defects of gas-insulated switchgear (GIS). It is of great significance to diagnose the types of insulation faults by recognizing PD to ensure the normal operation of GIS. However, the traditional diagnosis method based on single feature information analysis has a low recognition accuracy of PD, and there are great differences in the diagnosis effect of various insulation defects. To make the most of the rich insulation state information contained in PD, we propose a novel multi-information ensemble learning for PD pattern recognition. First, the ultra-high frequency and ultrasonic data of PD under four typical defects of GIS are obtained through experiment. Then the deep residual convolution neural network is used to automatically extract discriminative features. Finally, multi-information ensemble learning is used to classify PD types at the decision level, which can complement the shortcomings of the independent recognition of the two types of feature information and has higher accuracy and reliability. Experiments show that the accuracy of the proposed method can reach 97.500%, which greatly improves the diagnosis accuracy of various insulation defects.\",\n \"Title: XDAI: A Tuning-free Framework for Exploiting Pre-trained Language Models in Knowledge Grounded Dialogue Generation\\nYear: 2022\\n\\nAbstract: Large-scale pre-trained language models (PLMs) have shown promising advances on various downstream tasks, among which dialogue is one of the most concerned. However, there remain challenges for individual developers to create a knowledge-grounded dialogue system upon such big models because of the expensive cost of collecting the knowledge resources for supporting the system as well as tuning these large models for the task. To tackle these obstacles, we propose XDAI, a knowledge-grounded dialogue system that is equipped with the prompt-aware tuning-free PLM exploitation and supported by the ready-to-use open-domain external knowledge resources plus the easy-to-change domain-specific mechanism. With XDAI, the developers can leverage the PLMs without any fine-tuning cost to quickly create the open-domain dialogue systems as well as easily customize their own domain-specific systems. Extensive experiments including human evaluation, Turing test, and online evaluation have demonstrated the competitive performance of XDAI compared with the state-of-the-art general PLMs and specific PLMs for dialogue. XDAI pilots studies on the exploitation of PLMs and made intriguing findings which could be inspiring for the future research on other PLM-based applications. Developers and related researchers can get access to our repository at https://github.com/THUDM/XDAI, which presents a series of APIs, incremental toolkits and chatbot service of XDAI platform.\",\n \"Title: Accelerated Sampling Research Under Task Optimized Strategy for Multistate Systems\\nYear: 2022\\n\\nAbstract: The complex multi-state systems joint operation simulation and two task strategies are explored. For Monte Carlo sampling, based on the indirect sampling method, the principle of accelerated sampling methods (ASM), including forced transition (FT) and fault biasing (FB), is studied. It is found that the direct adoption of the current FT and FB will result in systematic bias for the calculation of task success metrics. For the bias, a state-transition chain truncation rule (SCTR) is proposed. In case study, after the simulation of various parameter combinations, it is found that when the sailing time is relatively smaller than the equipment reliability, which means a small probability event for the sampling of equipment faults, the ASM based on indirect sampling is applicable. Otherwise, the conventional sampling method should be used. The proposed state-transition chain truncation rule is also verified in case study.\",\n \"Title: Resilient Participant Selection Under Vulnerability Induced Colluding Attacks for Crowdsourcing\\nYear: 2022\\n\\nAbstract: This paper investigates the problem of participant selection considering colluding attacks for crowdsourcing. Compared with existing work, a practical vulnerability-induced colluding attack model is considered, where the malicious participants with different vulnerability levels collude with each other to perform attacks, which makes the participant selection problem more challenging. To address this problem, according to the structural characteristics of the colluding attack model, we derive the necessary condition and sufficient condition of achieving the colluding possibility minimization of the selected participants. A novel resilient participant selection algorithm is developed based on the necessary condition and sufficient condition. The proposed algorithm can select participants to complete tasks with the time complexity \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$O(mn)$</tex-math></inline-formula>\\n, where \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><tex-math notation=\\\"LaTeX\\\">$m, n$</tex-math></inline-formula>\\n are the numbers of participants and tasks, respectively. We analyze that the proposed algorithm achieves the colluding possibility minimization to defeat the vulnerability-induced colluding attack. It is also analyzed that the social cost of the proposed algorithm is smaller than existing algorithms in terms of the task-performing cost and the potential damage of the colluding attacks. Extensive real-world trace-based simulations are conducted to demonstrate the effectiveness of the proposed algorithm and the correctness of the theoretical results.\",\n \"Title: PINT: Parallel INTerval-Based Race Detector\\nYear: 2022\\n\\nAbstract: A race detector for task-parallel code typically consists of two main components - a reachability analysis component that checks whether two instructions are logically in parallel and an access history component that keeps track of memory locations accessed by previous instructions. Race detectors from prior work typically utilize a hashmap to maintain the access history, which provides asymptotically optimal overhead per operation but can incur significant overhead in practice, since the detector needs to insert into and query the hashmap for every memory access. An exception is STINT by Xu et al., which race detects task-parallel code by coalescing memory accesses into intervals, or continuous memory locations accessed within a sequence of instructions without any parallel construct. STINT utilizes a treap to manage access history that allows for insertions and queries of non-overlapping intervals. While a treap incurs higher asymptotic overhead per operation, this strategy works well in practice as the race detector performs operation on the access history with much lower frequency compared to the strategy that utilizes a hashmap. STINT only executes task-parallel code sequentially, however, due to the unique design of their treap that ensures no overlapping intervals exist in the tree. Parallelizing STINT efficiently is non-trivial, as it would require a concurrent treap that ensures no overlapping interval, which is challenging to design and likely incurs high synchronization overhead. This work proposes PINT, a race detector that, like STINT, race detects task-parallel code at the interval granularity and utilizes the same treap design to maintain access history. PINT executes the computation in parallel, however, while keeping the parallelization / synchronization overhead low. A key insight is that, PINT separates out operations needed for race detection into the core part (e.g., reachability maintenance) and the access history part. Doing so allows PINT to parallelize the core part efficiently and perform the access history part asynchronously, thereby incurring low overhead.\",\n \"Title: Fine-grained Micro-Expression Generation based on Thin-Plate Spline and Relative AU Constraint\\nYear: 2022\\n\\nAbstract: ABSTRACTAs a typical psychological stress reaction, micro-expression (ME) is usually quickly leaked on a human face and can reveal the true feeling and emotional cognition. Therefore,automatic ME analysis (MEA) has essential applications in safety, clinical and other fields. However, the lack of adequate ME data has severely hindered MEA research. To overcome this dilemma and encouraged by current image generation techniques, this paper proposes a fine-grained ME generation method to enhance ME data in terms of data volume and diversity. Specifically, we first estimate non-linear ME motion using thin-plate spline transformation with a dense motion network. Then, the estimated ME motion transformations, including optical flow and occlusion masks, are sent to the generation network to synthesize the target facial micro-expression. In particular, we obtain the relative action units (AUs) of the source ME to the target face as a constraint to encourage the network to ignore expression-irrelevant movements, thereby generating fine-grained MEs. Through comparative experiments on CASME II, SMIC and SAMM datasets, we demonstrate the effectiveness and superiority of our method. Source code is provided in https://github.com/MEA-LAB-421/MEGC2022-Generation.\",\n \"Title: Inconsistency-Based Multi-Task Cooperative Learning for Emotion Recognition\\nYear: 2022\\n\\nAbstract: Emotion recognition is an important part of affective computing. Human emotions can be described categorically or dimensionally. Accurate machine learning models for emotion classification and estimation usually depend on a large amount of annotated data. However, label acquisition in emotion recognition is costly: obtaining the ground-truth labels of an emotional sample usually requires multiple annotators’ assessments, which is expensive and time-consuming. To reduce the labeling effort in multi-task emotions recognition, the paper proposes an inconsistency measure that can indicate the difference between the labels estimated from the feature space and the label distribution of labeled dataset. Using the inconsistency as an indicator of sample informativeness, we further propose an inconsistency-based multi-task cooperative learning framework that integrates multi-task active learning and self-training semi-supervised learning. Experiments in two multi-task emotion recognition scenarios, multi-dimensional emotion estimation and simultaneous emotion classification and estimation, were conducted under this framework. The results demonstrated that the proposed multi-task active learning framework outperformed several single-task and multi-task active learning approaches.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":62,"string":"62"}}},{"rowIdx":63,"cells":{"question_id":{"kind":"string","value":"Francesco Piccialli"},"question":{"kind":"string","value":"Generate an abstract for the title \"Handling Uncertainty in Clustering Art-Exhibition Visiting Styles\" using the following items: 1. Uncertainty\n2. Clustering\n3. Big Data\n4. IoT\n5. Accuracy"},"answer":{"kind":"string","value":"Uncertainty is one of the most critical aspects that affect the quality of Big Data management and mining methods. Clustering uncertain data has traditionally focused on data coming from location- based services, sensor networks, or error-prone laboratory experiments. In this work we study for the first time the impact of clustering uncertain data on a novel context consisting in visiting styles in an art exhibition. We consider a dataset derived from the interaction of visitors of a museum with a complex Internet of Things (IoT) framework. We model this data as a set of uncertain objects, and cluster them by employing the well-established UK-medoids algorithm. Results show that clustering accuracy is positively impacted when data uncertainty is taken into account."},"correct_answer":{"kind":"string","value":"Uncertainty is one of the most critical aspects that affect the quality of Big Data management and mining methods. Clustering uncertain data has traditionally focused on data coming from location- based services, sensor networks, or error-prone laboratory experiments. In this work we study for the first time the impact of clustering uncertain data on a novel context consisting in visiting styles in an art exhibition. We consider a dataset derived from the interaction of visitors of a museum with a complex Internet of Things (IoT) framework. We model this data as a set of uncertain objects, and cluster them by employing the well-established UK-medoids algorithm. Results show that clustering accuracy is positively impacted when data uncertainty is taken into account."},"documents":{"kind":"list like","value":["Title: The Talking Museum Project.\nYear: 2013\n\nAbstract: In this paper, we present an ongoing project, named Talking Museum and developed within DATABENC - a high technology district for Cultural Heritage management. The project exploits the Internet of Things technologies in order to make objects of a museum exhibition able to “talk” during users’ visit and capable of automatically telling their story using multimedia facilities. In particular, we have deployed in the museum a particular Wireless Sensor Network that, using Bluetooth technology, is able to sense the surrounding area for detecting user devices’ presence. Once a device has been detected, the related MAC address is retrieved and a multimedia story of the closest museum objects is delivered to the related user. Eventually, proper multimedia recommendation techniques drive users towards other objects of possible interest to facilitate and make more stimulating the visit. As case of study, we show an example of Talking museum as a smart guide of sculptures’ art exhibition within the Maschio Angioino castle, in Naples (Italy).","Title: Mobile learning for clinical practice guidelines implementation: a medical app for pediatric acute gastroenteritis\nYear: 2013\n\nAbstract: Clinical practice guidelines (CPGs) are systematically developed documents that assist healthcare practitioners in making decisions about appropriate care for specific diseases based on evidence. In this context, acute gastroenteritis (AGE) in pediatrics is a suitable model for guidelines implementation and CPGs are available and very straightforward. Unfortunately, CPGs for AGE are poorly applied and most children receive not needed interventions. Mobile learning is a collaborative form of learning that can be used as a strategy of implementation for CPGs, for its portability and spreading capacity at a reasonable cost. In this paper we describe the development of a smartphone/tablet application for physicians providing guided decision making and carrying guidelines content about pediatric AGE in order to implement the pivotal recommendations from the CPGs and to foster their diffusion.","Title: SmARTweet: A Location-Based Smart Application for Exhibits and Museums\nYear: 2013\n\nAbstract: In this paper, we present \"Smartweed\", a Locationbased application developed within DATABENC, a high technology district for Cultural Heritage management. In particular, the project aims at exploiting several location-based services and technologies to realize a smart multimedia guide system able to detect the closest artworks to an user, make them able to \"tweet\" and \"talk\" during tourists' visit and capable of automatically telling their stories using multimedia facilities. Moreover, we have deployed and tested the installation of some sensors that, using Wi-Fi technology, allow to the users' mobile devices to detect the closest artwork in a museum environment. Once an artwork has been detected, the related identifier is retrieved and a multimedia story is delivered to user by means of proper multimedia delivery and user-profiling techniques, in order to facilitate and make more stimulating the visit. The artworks detection was performed by a localization algorithm that we designed and tested in our laboratory rooms. As case of study, we show an example of \"tweeting and talking artworks\" as a location-based application of a sculptures' art exhibition within the Maschio Angioino castle, in Naples - Italy.","Title: The C@Rolin@ Software A System For Monitoring Skills Development Of Children With Down Syndrome\nYear: 2011\n\nAbstract: The study of medical protocols for monitoring and analyzing the cognitive development of children with disabilities is a fundamental research area. In this context, a well established curriculum-based assessment is the Carolina Curriculum for Infants and Toddlers with Special Needs(CCITSN). This is a suitable curriculum for early intervention programs, where sequenced items data collection and analysis allow for monitoring, incremental program change, and recognition of areas of relative strength and weakness in children with mild, moderate, or severe disabilities.This paper describes the design and the development of an information system based on a client-server software application, named C@rolin@, which carries out all CCITSN abilities and more, for the monitoring and the analysis of data coming from a medical protocol for children with the Down syndrome. In particular, by means of user-friendly graphic interfaces, the C@rolin@ software helps users to add, modify, recover, and analyze data, to watch singular and aggregate data via customized reports, as well as to interpolate data among children to determine or prevent specific behaviors.","Title: A Regularized Mri Image Reconstruction Based On Hessian Penalty Term On Cpu/Gpu Systems\nYear: 2013\n\nAbstract: In this paper we investigate an inverse reconstruction problem of Magnetic Resonance Imaging with few acquired body scanner samples. The missing information in the Fourier domain causes image artefacts, therefore iterative computationally expensive recovery techniques are needed. We propose a regularization approach based on second order derivative of both simulated and real images with highly undersampled data, obtaining a good reconstruction accuracy. Moreover, an accelerated regularization algorithm, by using a projection technique combined with an implementation on Graphics Processing Unit (GPU) computing environment, is presented. The numerical experiments give clinically-feasible reconstruction runtimes with an increase in speed and accuracy of the MRI dataset reconstructions.","Title: A Novel Challenge into Multimedia Cultural Heritage: An Integrated Approach to Support Cultural Information Enrichment\nYear: 2013\n\nAbstract: In this paper we focus on the issue of pervasive applications and service development supporting cultural heritage. Modeling and creation of unified, structured and extensible artwork badge, here referred as booklet, represents the base to exploit such structured information as the building block for innovative amazing and more involving multimedia fruition paths in the cultural heritage domains. So we propose an integrated approach to cover multiple issues represented by: (i) enriching the collection of available information about artworks, from domain experts and well assessed sources, (ii) structuring of such heterogeneous information in a unified model, (iii) stimulating into no expert and, more generally, common people the attitude to take care and valorize cultural richness and goods, by the way of involving them to actively contribute to the composition and enrichment process of the artworks information and of proposing innovative and pervasive ways to enjoy cultural goods, even through the means of social networks channels and explicit feedback system. Common people's and domain experts' precious contributions have to be verified, merged, homogenized and structured to become knowledge, in the form of a booklet. To collect such data, there's the need to provide proper tools to people and new kinds of presentation and fruition experiences. In this perspective, we propose a prototypal framework architecture, organized as a Service Oriented Architecture (SOA) and focused on the modeling of knowledge and on the orchestration of a set of software services involved in the verification, merging and homogenization of different kinds of retrieved data.","Title: 3D data denoising via Nonlocal Means filter by using parallel GPU strategies.\nYear: 2014\n\nAbstract: Nonlocal Means (NLM) algorithm is widely considered as a state-of-the-art denoising filter in many research fields. Its high computational complexity leads researchers to the development of parallel programming approaches and the use of massively parallel architectures such as the GPUs. In the recent years, the GPU devices had led to achieving reasonable running times by filtering, slice-by-slice, and 3D datasets with a 2D NLM algorithm. In our approach we design and implement a fully 3D NonLocal Means parallel approach, adopting different algorithm mapping strategies on GPU architecture and multi-GPU framework, in order to demonstrate its high applicability and scalability. The experimental results we obtained encourage the usability of our approach in a large spectrum of applicative scenarios such as magnetic resonance imaging (MRI) or video sequence denoising.","Title: A location-based smart application applied to cultural heritage environments.\nYear: 2014\n\nAbstract: In this paper, we present a Location-based application developed within DATABENC, a high technology district for Cultural Heritage management. In particular, the project aims at exploiting several location-based services and technologies in order to realize a smart multimedia guide system. This system is able to detect the closest artworks to an user, make these artworks able to tweet and talk during users visit and capable of automatically telling their stories using multimedia facilities. Several experiments are performend in our laboratory by means of the installation of some sensors that, using Wi-Fi technology, allow the users mobile devices to detect the closest artwork as in a museum environment. The cultural items detection was performed by a localization algorithm designed and tested in our laboratory environment. As case of study, we show an example of tweeting and talking artworks as a location-based application of a sculptures art exhibition within the Maschio Angioino castle, in Naples Italy.","Title: SmaCH: A Framework for Smart Cultural Heritage Spaces\nYear: 2014\n\nAbstract: Cultural Heritage represents a world wide resource of inestimable value, attracting millions of visitors every year to monuments, museums and art exhibitions. A fundamental aspect of this resource is represented by its fruition and promotion. Indeed, to achieve a fruition of a cultural space that is sustainable, it is necessary to realize smart solutions for visitors' interaction to enrich their visiting experience. In this paper we present a service-oriented framework aimed to transform indoor Cultural Heritage sites in smart environments, which enforces a set of multimedia and communication services to support the changing of these spaces in an indispensable dynamic instrument for knowledge, fruition and growth for all the people. Following the Internet of Things paradigm, the proposed framework relies on the integration of a Wireless Sensor Network (WSN) with Wi-Fi and Bluetooth technologies to identify, locate and support visitors equipped with their own mobile devices.","Title: Designing a Smart Museum: When Cultural Heritage Joins IoT\nYear: 2014\n\nAbstract: The adoption of the Internet of Things (IoT) paradigm constitutes the basic building block to progress towards unified ICT platforms for a variety of applications within the large framework of the smart cities. Unfortunately, designing a general architecture for IoT is still a very complex challenge, since in such system may be involved several devices, link layer technologies and services. Cultural Heritage represents a worldwide resource of inestimable value and it gains more and more importance when embedded into the digital ecosystem of a smart city. In this paper we focus specifically to design a IoT architecture that is able to support the designing of a smart museum, a static cultural space that becomes intelligent thanks to the definition of an innovative model of sensors and services. Furthermore, the paper will present and discuss a real case of study, placed in a temporary art exhibition of sculptures in the Maschio Angioino Castle, located in Naples, Italy.","Title: Smart environments and Cultural Heritage: a novel approach to create intelligent cultural spaces\nYear: 2015\n\nAbstract: AbstractThe relationship between cultural heritage domain and new technologies has always been complex, dialectical and often inspired by the human desire to induce these spaces not created for that purpose, to pursue technological trends, eventually offering to the end-users devices and innovative technologies that could become a ‘dead weight’ during their cultural experiences. However, by means of innovative technological applications and location-based services it is possible to shorten the distance between cultural spaces and their visitors, nowadays determined by the purely aesthetic and essentially passive fruition of cultural objects. This paper presents the design and implementation of a novel multipurpose system for creating single smart spaces , a new concept of intelligent environment, that relies on innovative sensors board named smart crickets and an ad hoc proximity strategy; by following the Internet of Things paradigm the proposed system is able to transform a cultural space in a smart cultural environment to enhance the enjoyment and satisfaction of the involved people. To assess the effectiveness of our solution, we have experienced two real case studies, the first one situated within an art exhibition indoor, and the second one concerning an historical building outdoor. In this way, technology can become a mediator between visitors and fruition, an instrument of connection between people, objects and spaces to create new social, economic and cultural opportunities.","Title: Cultural Heritage and Social Pulse: A Semantic Approach for CH Sensitivity Discovery in Social Media Data\nYear: 2016\n\nAbstract: The demand for real-time business intelligence and the popularity of social media offer room for synthesis. A recent topic of interest in such perspective is Cultural Heritage, as empirically evidenced, in 2015, by Twitter introduction of the hashtag #culturalheritage. The opportunities offered by linking both concepts are acknowledged in the recent scientific literature, but a relative underexposure of quantitative studies devoted to assess the potential and effectiveness of social pulses and activities for supporting organizations promoting Cultural Heritage was recorded. In this work a data driven approach is proposed. Basing on the effective employment of domain specific and general ontologies, it aims to identify a set of Key Performance Indicators (KPIs) for quantitative estimation of Cultural Heritage Sensitivity as expressed by social network users. Quantitative analysis of huge datasets of tweets, combining Natural Language Processing (NLP), semantic technologies, geo-referencing and temporal analysis, and issued in a long period of time from geographical areas of Italy having different densities of CH resources, were performed. Examples of computed measures for characterizing people's interest and sensitivity into CH subjects, are geographical density of CH resources and temporal proximity to CHrelated events. Obtained results encourage a Business-Intelligence approach.","Title: SMuNe: A Smart Multisensor Network Based on Embedded Systems in IoT Environment.\nYear: 2015\n\nAbstract: Nowadays embedded systems have reached a great level of maturity and diffusion thanks to their small size, low power consumption, large connectivity and variety of application in everyday contexts. These systems, if properly structured and configured, can significantly increase the smartness of the environments where they are deployed, monitoring and continuously collecting data to be processed and elaborated. Such operations can be correctly executed, especially in large locations, if several embedded systems nodes are deployed under the design of an intelligent network. This paper presents SMuNe, a Smart Multisensor Network based on the BeableBone Black platform, a complete open hardware and software embedded computer, the challenge is to create a multi-purpose hierarchical network composed by smart nodes able to gain and manage heterogeneous data and spaces according to the Internet of Things (IoT) paradigm. As a proof of the effectiveness of SMuNe we conducted an experimentation within the Cultural Heritage domain, in detail we deployed SMuNe within a sculptures exhibition named \\\"The Beauty or the Truth\\\" in the monumental site of San Domenico Maggiore in Naples, Italy.","Title: Modelling the context evolution in Cultural Heritage domain: A graph approach\nYear: 2014\n\nAbstract: Nowadays, smart and pervasive environments are characterized by a large number of devices and related services offered to users. Providing the most appropriate services according to users behaviour and preferences is still a challenge and strongly depends on the user's current context. How it is well known, the context is often rich of data and very dynamic, and the users aim to continuously receive information about contextualised services. In this scenario, Cultural Heritage represents a domain where exchanged and produced data can be opportunely exploited by a set of applications and services in order to make the environment smart. This paper proposes a novel approach to represent and manage the evolution of context instances driven by events adopting a graph structure. As a case study, we propose an example of context evolution in an art exhibition within the Maschio Angioino castle, in Naples (Italy).","Title: The TrUST Project: Improving the Fruition of Historical Centres through Smart Objects\nYear: 2015\n\nAbstract: In the last few years, the Internet of Things (IoT) is evolving through a new definition of this paradigm describing a system of cooperating Smart Objects (SOs). An SO can be defined as a physical digital object augmented with sensing, processing, storing and networking capabilities. The key role of such objects resides in the capabilities they have to make physical environments intel- ligent so as to provide novel services to people. Cultural Heritage domain and in particular its fruition and enjoyment perspectives can profitably benefits of such technologies since it characterize a domain where different aspects have to be considered: people enjoyment, cultural items fruition, valorisation and tutelage of spaces and artworks. In this paper we present an ongoing project, named (TrUST - Transport with Ubiquiotus and Smart Technologies) and developed within DATABENC, a high technology district for Cultural Heritage management, in collaboration with the Mobility Transport Company (ANM) of Naples. The project exploits the Internet of Things technologies in order to enable a novel fruition metaphor inside the transport coaches. Deploying a SO with GPS and WiFi capabilities, users can enjoy of multimedia content about the cultural heritage that surrounds them during a trip.","Title: An Associative Engines Based Approach Supporting Collaborative Analytics in the Internet of Cultural Things.\nYear: 2017\n\nAbstract: Abstract In this paper we illustrate an integrated approach combining Business Intelligence, Big Data and Internet of Things (IoT), which is applied to information resources including structured and unstructured contents, Geo-Spatial and Social Network data, Multimedia (MM), multiple domain vocabularies, classifiers and ontologies. This is implemented in an information system which exploits Associative in-memory technologies in the context of Cloud Computing, as well as Semantic technologies for merging and analyzing information coming from heterogeneous sources. The primary aim is supporting Cultural Heritage Asset crowdsourcing, promotion, publication, management and usage. We describe and discuss, in particular, the application of this system for the analysis of behavior and interest of visitors in different types of populations and visits: on-site/ad-hoc (exhibitions, museums, cultural events) and territorial (historical downtown, archaeological or other touristic areas and routes including cultural resources). In this way it will be possible to provide a common ICT infrastructure and a set of advanced services for all types of subjects interested in the Cultural Heritage domain. The results of the experimentation encourage a Business Intelligence approach which is suitable for both nonprofit, research and business oriented organizations.","Title: A smart system to manage the context evolution in the Cultural Heritage domain.\nYear: 2016\n\nAbstract: Model the context evolution by means of a graph approach.Design a Context Evolution System (CES) to manage the context evolution and the consequently tailoring of data and services.Improve user experience by means of this kind of system.Our apporach is suitable within the Cultural Heritage domain. Nowadays intelligent and pervasive environments are characterized by a great number of devices and sensors that develop continuously and capture enormous amounts of data. Designing a context-aware system able to provide the most tailored services to users according to their behaviors, preferences and needs is still a research challenge. In such environments, although the context is very complex, dynamic and full of data captured and produced, users aspire to automatically receive contextualized services. The Cultural Heritage domain represents a domain where exchanged and produced data can be opportunely exploited by a set of applications and services in order to transform a static space into a smart environment. In this perspective, this paper presents a context-aware system named Context Evolution System (CES) able to represent and manage the evolution of the context through its instances; such an evolution is driven by occurring events and opportunely modeled by a graph structure. To assess the proposed solution, a Cultural Heritage case study of a real temporary art exhibition named the Beauty or the Truth and located in Naples (Italy) is presented and discussed.","Title: Sensitivity Mining in Social Pulses to Address Cultural Heritage Competitive Intelligence\nYear: 2016\n\nAbstract: AbstractThe remarkable opportunities of discovering interesting knowledge from Big Data can be exploited in the Cultural Heritage CH domain, where Social Data Mining could advantage cultural organizations and operators with strategical elements for enjoying and attracting and enjoy visitors, as well as to support knowledge sharing and diffusion processes. A challenging and profitable direction may be combining Social Media Pulses Mining with Business Intelligence, to reveal the underlying key performance indicators, so leading to a 'competitive intelligence' whose application well fits with CH. The main contribution of the proposed research is the application of a Multidimensional Text Mining over multiple dimensions for social media pulses analysis. A set of exploratory studies were performed on textual messages Twitter to explore multiple kind of relations between terms, their compliance with CH, and finally estimating the Social Sensitivity Indicator to this domain and its polarity. Advanced technologies for Big Data processing were exploited.","Title: A Service Oriented Framework for Analysing Social Network Activities.\nYear: 2016\n\nAbstract: Analysing and monitoring Social Networking activities raise multiple challenges for the evolution of Service Oriented Systems Engineering. This is particularly evident for event detection in social networks and, more in general, for large-scale Social Analytics, which require continuous processing of data. In this paper we present a service oriented framework exploring effective ways to leverage the opportunities coming from innovations and evolutions in computational power, storage, and infrastructures, with particular focus on modern architectures including in-memory database technology, in-database computation, massive parallel processing, Open Data Services, and scalability with multi-node clusters in Cloud. A prototype of this system was experimented in the contest of a specific kind of social event, an art exhibition of sculptures, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.","Title: A novel approach for automatic text analysis and generation for the cultural heritage domain.\nYear: 2017\n\nAbstract: Knowledge is information that has been contextualised in a certain domain, to be used or applied. It represents the basic core of our Cultural Heritage and Natural Language provides us with prime versatile means of construing experience at multiple levels of organization. The natural language generation field consists in the creation of texts providing information contained in other kind of sources (numerical data, graphics, taxonomies and ontologies or even other texts), with the aim of making such texts indistinguishable, as far as possible, from those created by humans. On the other hand, the knowledge extraction, basing on text mining and text analysis tasks, as examples of the many applications born from computational linguistic, provides summarization, categorization, topics extractions from textual resources using linguistic concepts, which deal with the imprecision and ambiguity of human language. This paper presents a research activity focused on exploring and scientifically describing knowledge structure and organization involved in textual resources' generation. Thus, a novel multidimensional model for the representation of conceptual knowledge, is proposed. Furthermore, a real case study in the Cultural Heritage domain is described to demonstrate the effectiveness and the feasibility of the proposed model and approach.","Title: A location-based IoT platform supporting the cultural heritage domain.\nYear: 2017\n\nAbstract: The Cultural Heritage domain is a global resource able to gain more and more importance and value because it becomes research field characterized by many aspects to be studied such as its enjoyment and promotion. In this paper, we present the design and the implementation of an intelligent Internet of Things (IoT) platform supporting the Cultural Heritage domain. In details, the objective of the proposed platform is to create intelligent solutions and services to enhance the visitors' interaction with cultural objects. To perform this research task, the platform relies on ubiquitous and IoT applications that can represent a suitable solution for improving visitors' experience when inside a museum or a temporary art exhibition. The IoT paradigm applied to the Cultural Heritage domain has the main purpose to transform a static cultural space into an intelligent environment enforcing a set of proximity-based and multimedia services. To assess our methodology, we realize a real case study during an art event in Naples, Italy.","Title: Social recommendation service for cultural heritage.\nYear: 2017\n\nAbstract: Cultural heritage is a domain in which new technologies and services have a special impact on people approach to its spaces. Technologies are changing the role of such spaces, allowing a more in-depth knowledge diffusion and social interactions. Static places become dynamic cultural environments in which people can discover and share new knowledge. Nowadays, cultural heritage is approaching to a new digital era in which people become active elements, as recipients of the actions ensuring the sustainability of such heritage, both moneywise but also simply as the perceived quality of life. In this perspective, this paper presents a novel recommender system to individual and people group in order to create a social recommendation service for cultural ICT applications. As key aspect of the presented work, we introduce a method for discovering and exploiting social affinity between users based on artwork features and user experience. In addition, we propose an architecture of the recommender system related with the affinity and discuss the architecture in terms of sparsity, group recommendation, and sustainability.","Title: IoT-based collaborative reputation system for associating visitors and artworks in a cultural scenario.\nYear: 2017\n\nAbstract: We design a CRS to establish the people reputation within Cultural spaces.The system is able to classify visitor behaviours.Our approach is suitable for both nonprofit and business oriented organizations. In this paper, starting from a comprehensive mathematical model of a Collaborative Reputation Systems (CRSes), we present a research study within the Cultural Heritage domain. The main goal of this study has been the evaluation and classification of the visitors behaviour during a cultural event. By means of mobile technological instruments, opportunely deployed within the environment, it is possible to collect data representing the knowledge to be inferred and give a reliable rate for both visitors and exposed artworks. Discussed results, confirm the reliability and the usefulness of CRSes for deeply understand dynamics related to people visiting styles.","Title: The Internet of Things Supporting Context-Aware Computing: A Cultural Heritage Case Study.\nYear: 2017\n\nAbstract: We're currently shifting from the Information Age to the Intelligence Age. The Intelligence Age will be characterized by autonomous communication between intelligent devices that are sensitive to a person's presence and respond by performing a specific task that enhances that person's lifestyle. In this perspective, the Internet of Things envisages a plethora of heterogeneous objects interacting with people and the physical environment. Things are able to sense a user's presence, movement and behaviour, analyse that data in order to learn about that user, and then make an intelligent decision to perform a task based on the data. Context-aware computing has proven to be successful in understanding data captured by sensors. In this paper, we present a Internet of Things (IoT) context-aware system and its application in the Cultural Heritage domain. Cultural Heritage is a domain where the widespread diffusion of ICT technology and sensors, within its spaces like museums, art exhibition, etc., can strongly enhance the quality of the offered services and subsequently create a Smart Cultural Environment.","Title: The Internet of Cultural Things: Towards a Smart Cultural Heritage\nYear: 2016\n\nAbstract: Cultural Heritage (CH) represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments, museums, exhibitions and historical centres. Fundamental aspects of this resource to be enhanced are the promotion, the tutelage, the safeguard and people enjoyment. The Internet of Things (IoT) paradigm applied to the Cultural Heritage domain is a novel concept integrating intelligent objects, sensors, services and applications within static cultural places. The objective is to transform these spaces into Smart Cultural Heritage environments. The Internet of Cultural Things is an emerging discipline aims to design a novel fruition, tutelage and promotion models of the Cultural Heritage in the worldwide. The designed and developed IoT systems will be able to be pervasive and ubiquitous with the definitive goal of rethinking CH in terms of sustainability, enrichment and valorisation towards the future generations. Furthermore, the Internet of Cultural Things can provide greater efficiency in the coordination of processes and facilitate the development of new activities that can generate economic returns.","Title: Designing a Service Oriented System for social analytics.\nYear: 2016\n\nAbstract: Event detection in social networks and, more in general, for large-scale Social Analytics, requires continuous monitoring and processing of huge volumes of data. In this paper we explored effective ways to leverage the opportunities coming from innovations and evolutions in computational power, storage, and infrastructures, with particular focus on modern architectures. In particular, we position a specific core technology and cloud platform adopted in our research with respect to micro-services. Furthermore, we demonstrate the application of some of its capabilities for performing data-intensive computations and implementing services in a real case of social analytics. A prototype of this system was experimented in the contest of a specific kind of social event, an art exhibition of sculptures, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.","Title: Understanding Customer Experience Diffusion on Social Networking Services by Big Data Analytics.\nYear: 2017\n\nAbstract: Social networking services (e.g., Facebook and Twitter) are playing a significant role of interacting with customers. In particular, most of businesses are trying to exploit such social networking services for more profit, since it has dramatically become an information carrier for customers who are disseminating latest information about products and services. Thus, this study examines how information shared by companies is distributed and what the important factors in understanding information dissemination are. More importantly, this study classifies the types of tweets posted by a company and then to investigate the effect of these types of tweets on diffusion. By using content analysis, this study defined three types, which are ) information provision (IF), ) advertisement (AD), and ) both (IFAD), with 8 specific concepts. These results indicate that the differences are significant for all three types of information content. It shows that companies can spread information more quickly by providing the IFAD type rather than the AD type.","Title: Spatio-Temporal Contextualization of Queries for Microtexts in Social Media: Mathematical Modeling.\nYear: 2017\n\nAbstract: In this paper, we present our ongoing project on query contextualization by integrating all possible IoT-based data sources. Most importantly, mobile users are regarded as the IoT sensors which can be the textual data sources with spatio-temporal contexts. Given a large amount of text streams, it has been difficult for the traditional information retrieval systems to conduct the searching tasks. The goal of this work is i) to understand and process microtexts in social media (e.g., Twitter and Facebook), and ii) to reformulate the queries for searching for relevant microtexts in these social media.","Title: Remarks on a computational estimator for the barrier option pricing in an IoT scenario.\nYear: 2017\n\nAbstract: The importance of derivatives in financial markets has known an exponential growth in the last decades, especially in risk management and speculation fields: this explains researchers’ interest in answering questions about this kind of contracts. In particular, in this paper we restrict our attention on European vanilla and barrier options, and we propose a statistical procedure to solve efficiently the problem of determining the no arbitrage price of this type of derivatives in an IoT context: starting form an Internet of Things (IoT) data flow, an IoT system takes information from several sources and stores it into a suitable database; this information is used in our estimation problem. Our scheme is based on some strong assumptions about the market model, in particular the completeness of the market, the log-normality of the underlying asset with a constant volatility.","Title: Control frameworks in network emulation testbeds: A survey.\nYear: 2017\n\nAbstract: Abstract The network emulation testbed is a promising research area because it provides a platform to fulfill testing requirements, creating emulated environments for conducting experiments. Through such testbeds, heterogeneous resources can be well controlled as emulated environment, and new ideas can be verified in the environment without interfering the real world. Thus, it can be used to reduce the time of the developers for conducting experiment to explore new inventions. Various kinds of network emulation testbed have been around for years, and it can be expected that more testbeds will emerge. To provide an integrated perspective of network emulation testbed, this paper surveys the issues associated in developing network emulation testbeds, including the state-of-the-art of architecture, the interoperability of orchestrating resources, and the way of managing components. Several wide-area, geographically distributed and large-scale network testbeds have been reviewed and discussed. Finally, critical research findings, open issues, and possible future research directions have also been provided.","Title: Smach: An Infrastructure For Smart Cultural Heritage Environments\nYear: 2017\n\nAbstract: Cultural heritage represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments and museums. Fundamental aspects of this resource to be investigated are its promotion and people enjoyment. Indeed, to achieve an enjoyment of a cultural space that is attractive, it is necessary to realise ubiquitous solutions for users' interaction to enrich their visiting experience and improve the knowledge transmission process. Thanks to ICT technologies, it is possible to shorten the distance between a cultural site and its visitors, and re-establish to them the truly educational role which provides the opportunity to produce new experiences of knowledge transmission. In this paper, we present a service-oriented infrastructure aimed to transform cultural heritage sites into smart environments. Following the Internet of Things paradigm, the proposed infrastructure relies on the integration of a wireless sensor network (WSN) with Wi-Fi and Bluetooth technologies to identify, locate and support users.","Title: S-InTime: A social cloud analytical service oriented system.\nYear: 2018\n\nAbstract: Social Networking activities raise multiple challenges for the evolution of Service Oriented Systems Engineering. The purpose of this research work is to demonstrate how a specific core technology and cloud platform with micro-services can be designed and used for performing data-intensive computations and implementing services in a real case of social analytics. In detail, we face the challenges of real-time data-intensive processing with the systematic application of in-memory view-based information modeling & computation, which is based on different types of non-materialized views without pre-aggregation of data. Finally, our study presents and compares design alternatives for these mappings, and demonstrates their effective application for implementing a large set of social analytics service types, with particular reference to the case of streaming sources of twitter data. A prototype of this system was experimented in the contest of a specific kind of social event, a permanent exhibition of Artworks, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.","Title: Editorial for FGCS special issue: The Internet of Cultural Things: Towards a Smart Cultural heritage.\nYear: 2018\n\nAbstract: Cultural Heritage (CH) represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments, museums, events and exhibitions. Fundamental aspects of this resource to be enhanced are the promotion, the tutelage, the safeguard and people enjoyment.","Title: Centrality in heterogeneous social networks for lurkers detection: An approach based on hypergraphs.\nYear: 2018\n\nAbstract: Nowadays, social networks provide users an interactive platform to create and share heterogeneous content for a lot of different purposes (eg, to comment events and facts, and express and share personal opinions on specific topics), allowing millions of individuals to create online profiles and share personal information with vast networks known and sometimes also unknown people. Knowledge about users, content, and relationships in a social network may be used for an adversary attack of some victims easily. Although a number of works have been done for data privacy preservation on relational data, they cannot be applied in social networks and in general for big data analytics. In this paper, we first propose a novel data model that integrates and combines information on users belonging to 1 or more heterogeneous online social networks, together with the content that is generated, shared, and used within the related environments, using an hypergraph data structure; then we implemented the most diffused centrality measures and also introduced a new centrality measurebased on the concept of neighborhood among usersthat may be efficiently applied for a number of data privacy issues, such as lurkers and neighborhood attack prevention, especially in interest-based social networks. Some experiments using the Yelp dataset are discussed.","Title: A Framework for Assessing Reusability Using Package Cohesion Measure in Aspect Oriented Systems.\nYear: 2018\n\nAbstract: Due to better modularization of crosscutting concerns, the Aspect oriented programming approach enhances the quality of the system as it results in less complex and more readable implementation of the system. As the software applications grow in size and complexity, they require some kind of high level organization. For high level organization of software system, packages are required. A lot of work has been carried out for measuring cohesion in Aspect Oriented Systems (AOS) at class level but very less research has been done for designing package level cohesion metric. Package cohesion metrics plays an important role in analyzing quality of software at package level. According to object oriented design principle, a good software design must have high cohesion with high reusability. Thus a relationship must therefore exist between cohesion and reusability. Number of attempts has been made to evaluate effect of cohesion on external attributes but at class level only. Impact of package level cohesion metrics on reusability for AOS is not yet explored. (a) To implement the proposed package cohesion measure, PCohA, on AspectJ sample packages, (b) to theoretically validate the proposed measure and (c) to find the impact of package cohesion on measuring reusability for AOS. Theoretical validation has been done by proving its validity on four theorems given by Briand et al. For finding the impact of proposed measure on external attributes, correlation has been found between package cohesion, PCohA, and external attribute—reusability. After theoretical validation, it has been proved that the proposed measure is suitable for measuring cohesion at package level. Correlation between package cohesion metric (PCohA) and reusability is calculated by using Karl Pearson Product Moment correlation. The computed values show a strong positive relation between PCohA and Reusability. The proposed package cohesion measure is found to be a useful indicator of external quality factors such as reusability. The proposed metric is also established as a better predictor of code reusability than the existing cohesion measures. The work discussed in this paper can be used for designing high quality software by developing new package level metrics for other quality attributes such as maintainability, changeability etc. as a future work.","Title: A GPU Implementation of OLPCA Method in Hybrid Environment.\nYear: 2018\n\nAbstract: Sophisticated denoising algorithms are used to improve image quality in the Magnetic Resonance Imaging field. Of course, better results are obtained by implementing computationally expensive schemes. In this paper, we consider the Overcomplete Local Principal Component Analysis (OLPCA) method for image denoising and its main issues. More in detail, we investigated the impact of the Singular Value Decomposition on the OLPCA algorithm and its high computational cost. Moreover, we propose a fine-to-coarse parallelization strategy in order to exploit a parallel hybrid architecture and we implement a multilevel parallel software as a smart combination between codes using NVIDIA cuBLAS library for Graphic Processor Units (GPUs) and the standard Message Passing Interface library for cluster programming. Experimental results show improvements in terms of execution time with a promising speed up with respect to the CPU and our old GPU versions.","Title: A (Multi) Gpu Iterative Reconstruction Algorithm Based On Hessian Penalty Term For Sparse Mri\nYear: 2018\n\nAbstract: A recent trend in the Magnetic Resonance Imaging (MRI) research field is to design and adopt machines that are able to acquire undersampled clinical data, reducing the time for which the patient is lying in the body scanner. Unfortunately, the missing information in these undersampled acquired datasets leads to artefacts in the reconstructed image; therefore, computationally expensive image reconstruction techniques are required. In this paper, we present an iterative regularisation strategy with a second-order derivative penalty term for the reconstruction of undersampled image datasets. Moreover, we compare this approach with other constrained minimisation methods, resulting in improved accuracy. Finally, an implementation on a massively parallel architecture environment, a multi Graphics Processing Unit (GPU) system, of the proposed iterative algorithm is presented. The resulting performance gives clinically-feasible reconstruction run times, speed-up and improvements in terms of reconstruction accuracy of the undersampled MRI images.","Title: An inverse Bayesian scheme for the denoising of ECG signals.\nYear: 2018\n\nAbstract: The ECG filtering problem is a widely explored research topic. In this paper we propose a novel methodology taking into account some “a priori” information on the signal components that gives significant improvements in the denoising task. Our approach is a modification of recursive filtering (RF) by considering a probabilistic Bayesian framework that is adopted to remove selectively artifacts from the signals without the loss of any crucial medical information on the acquired data. The proposed scheme is very efficient from the computational point of view and this feature makes it ready as a useful tool for application in mobile devices equipped with specific sensors. Finally, numerical experiments have been carried out on real data to assess the advantages of the algorithm.","Title: A Robust Features-Based Person Tracker for Overhead Views in Industrial Environment.\nYear: 2018\n\nAbstract: A top view camera having wide range lens installed overhead of the objects contributes greatly toward resolving the tracking problem and also maintains comprehensive visual access of the environment. Video analytics becoming more important to Internet of Things applications including automatic people monitoring and surveillance systems. We followed an approach based on machine learning features-ba...","Title: A Perspective On Applications Of In-Memory And Associative Approaches Supporting Cultural Big Data Analytics\nYear: 2018\n\nAbstract: Business intelligence, advanced analytics, big data, in-memory database and associative technologies are actually the key enablers for enhanced business decision making. In this paper, we provide a perspective on applications of in-memory approaches supporting analytics in the field of the cultural heritage applied to information resources including structured and unstructured contents, geo-spatial and social network data, multimedia (MM), multiple domain vocabularies, classifiers and ontologies. The proposed approach has been implemented in an information system exploiting associative in-memory technologies in a cloud context, as well as integrating semantic technologies for merging and analysing information coming from heterogeneous sources. We analyse and describe the application of this system to trace a behavioural and interest profile of users and visitors for cultural events (exhibitions, museums, etc.) and territorial (tourist areas and routes including cultural resources, historical down-town, and archaeological sites). The results of ongoing experimentation encourage a business intelligence approach which is suitable for supporting cultural heritage asset crowdsourcing, promotion, publication, management and usage.","Title: Self And Social Network Behaviours Of Users In Cultural Spaces\nYear: 2018\n\nAbstract: Many cultural spaces offer their visitors the use of ICT tools to enhance their visit experience. Data collected within such spaces can be analysed in order to discover hidden information related to visitors' behaviours and needs. In this paper, a computational model inspired by neuroscience simulating the personalised interactions of users with cultural heritage objects is presented. We compare a strengthened validation approach for neural networks based on classification techniques with a novel proposal one, based on clustering strategies. Such approaches allow us to identify natural users' groups in data and to verify the model responses in terms of user interests. Finally, the presented model has been extended to simulate social behaviours in a community, through the sharing of interests and opinions related to cultural heritage assets. This data propagation has been further analysed in order to reproduce applicative scenarios on social networks.","Title: Reproducing dynamics related to an Internet of Things framework: A numerical and statistical approach.\nYear: 2018\n\nAbstract: In the Cultural Heritage domain, novel fruition and enjoyment approaches, based on Internet of Things (IoT) paradigm, have the effect to change the way people experiencing cultural spaces, such as museums and exhibitions. Within these environments, a main challenge is to classify and forecast the behaviours of visitors by collecting their movements, choices and needs. In this paper, starting from the design of an IoT system for collecting behavioural data, we propose and discuss a model able to reproduce, and then “predict”, the dynamics related to the interactions of the visitors with the exposed artworks and, in particular, with the available technologies. Generally, collected data are affected by many kinds of errors; to address this issue a powerful statistical method to reproduce the dynamics related to the visiting styles of the spectators is proposed. Numerical experiments on real data have been reported in order to assess the proposed methodology.","Title: Implications of deep learning for the automation of design patterns organization.\nYear: 2018\n\nAbstract: Though like other domains such as email filtering, web page classification, sentiment analysis, and author identification, the researchers have employed the text categorization approach to automate organization and selection of design patterns. However, there is a need to bridge the gap between the semantic relationship between design patterns (i.e. Documents) and the features which are used for the organization of design patterns. In this study, we propose an approach by leveraging a powerful deep learning algorithm named Deep Belief Network (DBN) which learns on the semantic representation of documents formulated in the form of feature vectors. We performed a case study in the context of a text categorization based automated system used for the classification and selection of software design patterns. In the case study, we focused on two main research objectives: 1) to empirically investigate the effect of feature sets constructed through the global filter-based feature selection methods besides the proposed approach, and 2) to evaluate the significant improvement in the classification decision (i.e. Pattern organization) of classifiers using the proposed approach. The adjustment of DBN parameters such as a number of hidden layers, nodes and iteration can aid a developer to construct a more illustrative feature set. The experimental promising results suggest the significance of the proposed approach to construct a more representative feature set and improve the classifier’s performance in terms of organization of design patterns.","Title: Remarks of Social Data Mining Applications in the Internet of Data.\nYear: 2018\n\nAbstract: Social network analysis attracted interests from both the research and business communities for a strong potential and variety of applications. In addition, this interest has been fuelled by the large success of online social networking sites and the subsequent abundance of social network data produced. A key aspect in this research field is the influence maximization in social networks. In this paper we discuss an overview about the models and the approaches widely used to analyse social networks. In this context, we also discuss data preparation and privacy concerns also considering different kind of approaches based on centrality measures.","Title: Serious Games and In-Cloud Data Analytics for the Virtualization and Personalization of Rehabilitation Treatments.\nYear: 2019\n\nAbstract: During the last years, the significant increase in the number of patients in need of rehabilitation has generated an unsustainable economic impact on healthcare systems, implying a reduction in therapeutic supervision and support for each patient. To address this problem, this paper proposes a telerehabilitation system based on serious games and in-cloud data analytics services, in accordance with...","Title: SOS: A multimedia recommender System for Online Social networks.\nYear: 2019\n\nAbstract: The use of Online Social Networks has been rapidly increased over the last years. In particular, Social Media Networks allow people to communicate, share, comment and observe different types of multimedia content. This phenomenon produces a huge amount of data showing Big Data features, mainly due to their high change rate, large volume and intrinsic heterogeneity. In this perspective, in the last decade Recommender Systems have been introduced to support the browsing of such data collections, assisting users to find “what they really need” within this ocean of information. In this research work, we propose and describe a novel recommending system for big data applications able to provide recommendations on the base of the interactions among users and the generated multimedia contents in one or more social media networks. The proposed system relies on a “user-centered” approach. An experimental campaign, using data coming from many social media networks, has been performed in order to assess the proposed approach also showing how it can obtain very promising results.","Title: Enabling multimedia aware vertical handover Management in Internet of Things based heterogeneous wireless networks.\nYear: 2017\n\nAbstract: Enabling seamless connectivity in Internet of Things (IoT) based heterogeneous wireless networks and pervasive use of smartphones in daily life require high data speed and always-best-connected services. However, providing vertical handover management in heterogeneous wireless networks is a difficult and challenging task. Moreover, various issues are present in the current vertical handover management schemes such as inappropriate handover triggering, high handover delay, wrong network selection, etc. In order to address the aforementioned issues, we propose a generic vertical handover management scheme. Our research is twofold; firstly, the Mobile Node (MN) dynamically checks the data rate required by the applications running on the MN’s device. If the data rate drops below a predefined threshold, the MN initiates the handover. Secondly, the network selection is performed by considering various parameters such as end-to-end delay, jitter, Bit Error Rate, and packet loss. The Artificial Bee Colony (ABC) optimization algorithm uses the above parameters to select the target network with minimum handover delay and time. The proposed scheme is compared with the Simple Additive Weighting (SAW), Weighted Product Method (WPM), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and Fuzzy TOPSIS in context of energy consumption, throughput, average MN’s stay time in a network, handover delay, and handover time. The experimental results show that the proposed vertical handover management scheme outperforms the existing schemes used for similar purpose.","Title: A computational method for the European option price in an Internet of Things framework\nYear: 2020\n\nAbstract: In an Internet of Things (IoT) scenario, sensors and devices are able to: (i) extract information from real; (ii) storage them into a database; (iii) use this information for inferring results by the implementation of very efficient algorithms. In this paper we present a computational schema in which, in order to price financial European options, an IoT framework processes data, as financial assets, expiration day, interest rate, strike price. In particular, this procedure involves mathematical tools for the estimation of the volatility and for the calculation of the no arbitrage price. The mathematical model is translated into an algorithm that is implemented in a mobile software. To test its validity, we apply our schema to a real case.","Title: Pricing estimation of a barrier option in an IoT scenario\nYear: 2020\n\nAbstract: IoT systems are able to manage very great amount of different types of data. In our paper we propose a mobile app which uses data processed by an IoT framework to estimate the price of a European barrier price. This software is based on an algorithm: in input it receives the values of maturity, strike price, interest rate, barrier level and in output it gives the value of the price. The algorithm implements a mathematical procedure involving numerical and statistical issues, as quadrature formulas and statistical tests. The validity of our methodology is verified by applying it to a real case.","Title: Traditional and Deep Learning Approaches to Information and Influence Propagation in Social Networks.\nYear: 2018\n\nAbstract: Social network analysis is an interdisciplinary topic attracting researchers from biology, economics, psychology, and machine learning. It has attracted interests from both the research and business communities for a strong potential and variety of applications. Also, this interest has been fueled by the large success of online social networking sites and the subsequent abundance of social network data produced. An important aspect in this research field is influence maximization in social networks. The goal is to find a set of individuals to be targeted, with the aim to drive social contagion and generate a diffusion cascade. We provide here an overview of the models and approaches used to analyze interaction networks. The challenges this problem introduces are recently being tackled using Deep Learning approaches such as Recurrent Neural Networks (RNNs) which are particularly suited to model sequence inputs.","Title: Lessons learned from longitudinal modeling of mobile-equipped visitors in a complex museum\nYear: 2020\n\nAbstract: Cultural sites are evolving toward smart environments, including the notion of hyper-connected museums. In this context, stakeholders of cultural assets need more advanced and comprehensive ICT systems for monitoring and modeling visitors behaviors. In this paper, we discuss the results of a longitudinal research study embracing multiple seasons, in a complex cultural structure including outdoor and indoor attractions, multiple floors and multiple routes for visitors. Here, interactive mobile devices were used for both offering multimedial context-aware assistance to visitors and monitoring services to museum stakeholders. We deeply analyzed the data using an unsupervised classification approach, obtaining a model where the number of distinct user profiles and the number of features were considered not trivial as well as not too complex for museum stakeholders.\nWe observed that some optimistic expectations about visitor performances were only partially met, devising possible explanations in terms of the different user profiles and features of the model. Finally, we also compared some outcomes from our interactive system with those obtained in another complex cultural structure using a noninvasive monitoring system.","Title: General Paradigm of Edge-Based Internet of Things Data Mining for Geohazard Prevention\nYear: 2021\n\nAbstract: Geological hazards (geohazards) are geological processes or phenomena formed under external-induced factors causing losses to human life and property. Geohazards are sudden, cause great harm, and have broad ranges of influence, which bring considerable challenges to geohazard prevention. Monitoring and early warning are the most common strategies to prevent geohazards. With the development of the internet of things (IoT), IoT-based monitoring devices provide rich and fine data, making geohazard monitoring and early warning more accurate and effective. IoT-based monitoring data can be transmitted to a cloud center for processing to provide credible data references for geohazard early warning. However, the massive numbers of IoT devices occupy most resources of the cloud center, which increases the data processing delay. Moreover, limited bandwidth restricts the transmission of large amounts of geohazard monitoring data. Thus, in some cases, cloud computing is not able to meet the real-time requirements of geohazard early warning. Edge computing technology processes data closer to the data source than to the cloud center, which provides the opportunity for the rapid processing of monitoring data. This article presents the general paradigm of edge-based IoT data mining for geohazard prevention, especially monitoring and early warning. The paradigm mainly includes data acquisition, data mining and analysis, and data interpretation. Moreover, a real case is used to illustrate the details of the presented general paradigm. Finally, this article discusses several key problems for the general paradigm of edge-based IoT data mining for geohazard prevention.","Title: Optimizing makespan and resource utilization for multi-DNN training in GPU cluster\nYear: 2021\n\nAbstract: Deep neural network (DNN) has been widely applied in many fields of artificial intelligence (AI), gaining great popularity both in industry and academia. Increasing the size of DNN models does dramatically improve the learning accuracy. However, training large-scale DNN models on a single GPU takes unacceptable waiting time. In order to speed up the training process, many distributed deep learning (DL) systems and frameworks have been published and designed for parallel DNN training with multiple GPUs. However, most of the existing studies concentrate only on improving the training speed of a single DNN model under centralized or decentralized systems with synchronous or asynchronous approaches. Few works consider the issue of multi-DNN training on the GPU cluster, which is the joint optimization problem of job scheduling and resource allocation. This paper proposes an optimizing makespan and resource utilization (OMRU) approach to minimize job completion time and improve resource utilization for multi-DNN training in a GPU cluster. Specifically, we first collect the training speed/time data of all DNN models by running a job for one epoch on a different number of GPUs. The OMRU algorithm, integrating job scheduling, resource allocation, and GPU reuse strategies, is then devised to minimize the total job completion time (also called makespan) and improve GPU cluster resource utilization. The linear scaling rule (LSR) is adopted for adjusting the learning rate when a DNN model is trained on multiple GPUs with large minibatch size, which can guarantee model accuracy without the other hyper-parameters tune-up. We implement the OMRU algorithm on the Pytorch with Ring-Allreduce communication architecture and a GPU cluster with 8 nodes, each of which has 4 NVIDIA V100 GPUs. Experimental results on image classification and action recognition show that OMRU achieves a makespan reduction of up to 30% compared to the baseline scheduling algorithms and reach an average of 98.4% and 99.2% resource utilization on image classification and action recognition, respectively, with the state-of-the-art model accuracy.","Title: Predictive Analytics for Smart Parking: A Deep Learning Approach in Forecasting of IoT Data\nYear: 2021\n\nAbstract: AbstractNowadays, a sustainable and smart city focuses on energy efficiency and the reduction of polluting emissions through smart mobility projects and initiatives to “sensitize” infrastructure. Smart parking is one of the building blocks of intelligent mobility, innovative mobility that aims to be flexible, integrated, and sustainable and consequently integrated into a Smart City. By using the Internet of Things (IoT) sensors located in the parking areas or the underground car parks in combination with a mobile application, which indicates to citizens the free places in the different areas of the city and guides them toward the chosen parking, it is possible to reduce air pollution and fluidifying noise traffic. In this article, we present and discuss an innovative Deep Learning-based ensemble technique in forecasting the parking space occupancy to reduce the search time for parking and to optimize the flow of cars in particularly congested areas, with an overall positive impact on traffic in urban centres. A genetic algorithm has also been used to optimize predictors parameters. The main goal is to design an intelligent IoT-based service that can predict, in the next few hours, the parking spaces occupancy of a street. The proposed approach has been assessed on a real IoT dataset composed by over than 15M of collected sensor records. Obtained results demonstrate that our method outperforms both single predictors and the widely used strategy of the mean providing inherently robust predictions.","Title: Predictive Medicine for Salivary Gland Tumours Identification Through Deep Learning\nYear: 2022\n\nAbstract: Nowadays, predictive medicine begins to become a reality thanks to Artificial Intelligence (AI) which allows, through the processing of huge amounts of data, to identify correlations not perceptible to the human brain. The application of AI in predictive diagnostics is increasingly pervasive; through the use and interpretation of data, the first signs of some diseases (i.e. tumours) can be detected to help physicians make more accurate diagnoses to reduce the errors and develop methods for individualized medical treatment. In this perspective, salivary gland tumours (SGTs) are rare cancers with variable malignancy representing less than 1% of all cancer diagnoses and about 5% of head and neck cancers. The clinical management of SGTs is complicated by a high rate of preclinical diagnostic errors. Today, fine needle aspiration cytology (FNAC) represents the primary diagnostic tool in the hands of clinicians. However, it provides information that about 25% of cases are dubious or inconclusive, complicating therapeutic choices. Thus, finding new tools supporting clinicians to make the right choices in doubtful cases is necessary. This research work presents and discusses a Deep Learning-based framework for automatic segmentation and classification of salivary gland tumours. Furthermore, we propose an explainable segmentation learning approach supporting the effectiveness of the proposed framework through a per-epoch learning process analysis and the attention map mechanism. The proposed framework was evaluated with a collected CT dataset of patients with salivary gland tumours. Experimental results show that our methodology achieves significant scores on both segmentation and classification tasks.","Title: Scientific Machine Learning Through Physics–Informed Neural Networks: Where we are and What’s Next\nYear: 2022\n\nAbstract: Physics-Informed Neural Networks (PINN) are neural networks (NNs) that encode model equations, like Partial Differential Equations (PDE), as a component of the neural network itself. PINNs are nowadays used to solve PDEs, fractional equations, integral-differential equations, and stochastic PDEs. This novel methodology has arisen as a multi-task learning framework in which a NN must fit observed data while reducing a PDE residual. This article provides a comprehensive review of the literature on PINNs: while the primary goal of the study was to characterize these networks and their related advantages and disadvantages. The review also attempts to incorporate publications on a broader range of collocation-based physics informed neural networks, which stars form the vanilla PINN, as well as many other variants, such as physics-constrained neural networks (PCNN), variational hp-VPINN, and conservative PINN (CPINN). The study indicates that most research has focused on customizing the PINN through different activation functions, gradient optimization techniques, neural network structures, and loss function structures. Despite the wide range of applications for which PINNs have been used, by demonstrating their ability to be more feasible in some contexts than classical numerical techniques like Finite Element Method (FEM), advancements are still possible, most notably theoretical issues that remain unresolved.","Title: An unsupervised learning framework for marketneutral portfolio\nYear: 2022\n\nAbstract: In this paper, we present a portfolio optimization strategy based on a novel approach in assets clustering on the financial background of the Arbitrage Pricing Theory, a well-known multi-factor model. In particular, our aim is to exploit data analysis tools, such as the techniques of features extraction and feature selection, to group assets that exhibit a significant exposition to the same risk factors. Then, we exploit the clustering to build a market-neutral portfolio and, more in general, an investment methodology that takes into account the peculiarities of the specific market. Finally, we apply our methodology in various case studies, discussing the results obtained and highlighting the strengths and the limits of the proposed strategy.","Title: Explainable Deep Learning Models on the Diagnosis of Pneumonia\nYear: 2021\n\nAbstract: Pneumonia is a lung infection caused by pathogens such as bacteria and viruses. If the diagnosis is not timely and the treatment cannot be performed in time, it may threaten the life of the patient. Currently, the most common method for the diagnosis of pneumonia is to take chest X-rays and perform manual diagnosis. However, manual diagnosis is less efficient and highly subjective. In this paper, we present a deep learning approach for X-ray image identification of pneumonia and conducts the corresponding explainability. The essential idea is to use the existing pre-trained deep learning model and the Grad-CAM method to construct an explainable deep learning model of pneumonia X-ray image recognition. In the proposed deep learning model, ResNet50 and VGG16 models can achieve higher accuracy after data augmentation. The proposed deep learning model could be applied to the computer-aided diagnosis of pneumonia to achieve efficient detection and diagnosis of pneumonia.","Title: Neurocomputing for internet of things: Object recognition and detection strategy\nYear: 2022\n\nAbstract: Modern and new integrated technologies have changed the traditional systems by using more advanced machine learning, artificial intelligence methods, new generation standards, and smart and intelligent devices. The new integrated networks like the Internet of Things (IoT) and 5G standards offer various benefits and services. However, these networks have suffered from multiple object detection, localization, and classification issues. Conventional Neural Networks (CNN) and their variants have been adopted for object detection, classification, and localization in IoT networks to create autonomous devices to make decisions and perform tasks without human intervention and helpful to learn in-depth features. Motivated by these facts, this paper investigates existing object detection and recognition techniques by using CNN models used in IoT networks. This paper presents a Conventional Neural Networks for 5G-Enabled Internet of Things Network (CNN-5GIoT) model for moving and static objects in IoT networks after a detailed comparison. The proposed model is evaluated with existing models to check the accuracy of real-time tracking. The proposed model is more efficient for real-time object detection and recognition than conventional methods.","Title: From Artificial Intelligence to Explainable Artificial Intelligence in Industry 4.0: A Survey on What, How, and Where\nYear: 2022\n\nAbstract: Nowadays, Industry 4.0 can be considered a reality, a paradigm integrating modern technologies and innovations. Artificial intelligence (AI) can be considered the leading component of the industrial transformation enabling intelligent machines to execute tasks autonomously such as self-monitoring, interpretation, diagnosis, and analysis. AI-based methodologies (especially machine learning and deep...","Title: An Efficient Deep Learning Approach Using Improved Generative Adversarial Networks for Incomplete Information Completion of Self-driving Vehicles\nYear: 2022\n\nAbstract: Autonomous driving is a key technology for intelligent logistics in the Industrial Internet of Things (IIoT). In autonomous driving, the appearance of incomplete point clouds that lose geometric and semantic information is inevitable due to the limitations of occlusion, sensor resolution, and viewing angle when Light Detection And Ranging (LiDAR) is applied. The existence of incomplete point clouds, especially incomplete vehicle point clouds, would lead to a reduction in the accuracy of object detection, traffic alerts, and collision avoidance for autonomous driving vehicles. Existing point cloud completion networks, such as the Point Fractal Network (PF-Net), focus on the accuracy of point cloud completion without considering the efficiency of the inference process, which makes it difficult for them to be deployed for vehicle point cloud repair in autonomous driving. To address this problem, in this paper, we propose an efficient deep learning approach to repair incomplete vehicle point clouds in autonomous driving accurately and efficiently. In the proposed method, an efficient downsampling algorithm that combines incremental sampling and one-time sampling is presented to improve the inference speed of the PF-Net based on Generative Adversarial Network (GAN). To evaluate the performance of the proposed method, a real dataset is used, and autonomous driving scenes are created, where three incomplete vehicle point clouds with 5 different sizes are used for three autonomous driving situations. The improved PF-Net can achieve speedups of over 19x with almost the same accuracy when compared to the original PF-Net. Experimental results demonstrate that the improved PF-Net can be applied to efficiently complete vehicle point clouds in autonomous driving.","Title: SWCGAN: Generative Adversarial Network Combining Swin Transformer and CNN for Remote Sensing Image Super-Resolution\nYear: 2022\n\nAbstract: Easy and efficient acquisition of high-resolution remote sensing images is of importance in geographic information systems. Previously, deep neural networks composed of convolutional layers have achieved impressive progress in super-resolution reconstruction. However, the inherent problems of the convolutional layer, including the difficulty of modeling the long-range dependency, limit the performance of these networks on super-resolution reconstruction. To address the abovementioned problems, we propose a generative adversarial network (GAN) by combining the advantages of the swin transformer and convolutional layers, called SWCGAN. It is different from the previous super-resolution models, which are composed of pure convolutional blocks. The essential idea behind the proposed method is to generate high-resolution images by a generator network with a hybrid of convolutional and swin transformer layers and then to use a pure swin transformer discriminator network for adversarial training. In the proposed method, first, we employ a convolutional layer for shallow feature extraction that can be adapted to flexible input sizes; second, we further propose the residual dense swin transformer block to extract deep features for upsampling to generate high-resolution images; and third, we use a simplified swin transformer as the discriminator for adversarial training. To evaluate the performance of the proposed method, we compare the proposed method with other state-of-the-art methods by utilizing the UCMerced benchmark dataset, and we apply the proposed method to real-world remote sensing images. The results demonstrate that the reconstruction performance of the proposed method outperforms other state-of-the-art methods in most metrics.","Title: Deep Learning for Secure Communication in Cyber-Physical Systems\nYear: 2022\n\nAbstract: The proliferation of ubiquitous cyber-physical systems (CPSs) that integrate emerging applications of embedded computers and communication technologies into various physical domains exposes them to distinct security challenges. Deep learning (DL) is a promising solution in securing CPS communication by detecting diverse unknown attacks. In this article, we demonstrate the significant potential of DL-based solutions to address the challenges of secure communications in CPSs. First, we outline classic challenges in CPS secure communication. Second, we introduce deep neural networks that are available to address these challenges in CPS secure communication. Third, we demonstrate DL-based solutions for mitigating the challenges in CPS secure communication. Specifically, we discuss the application of DL-based solutions and design two experiments for anomaly detection in CPS secure communication. The remarkable performance of the experimental results demonstrates the effectiveness of DL-based solutions in CPS secure communication."],"string":"[\n \"Title: The Talking Museum Project.\\nYear: 2013\\n\\nAbstract: In this paper, we present an ongoing project, named Talking Museum and developed within DATABENC - a high technology district for Cultural Heritage management. The project exploits the Internet of Things technologies in order to make objects of a museum exhibition able to “talk” during users’ visit and capable of automatically telling their story using multimedia facilities. In particular, we have deployed in the museum a particular Wireless Sensor Network that, using Bluetooth technology, is able to sense the surrounding area for detecting user devices’ presence. Once a device has been detected, the related MAC address is retrieved and a multimedia story of the closest museum objects is delivered to the related user. Eventually, proper multimedia recommendation techniques drive users towards other objects of possible interest to facilitate and make more stimulating the visit. As case of study, we show an example of Talking museum as a smart guide of sculptures’ art exhibition within the Maschio Angioino castle, in Naples (Italy).\",\n \"Title: Mobile learning for clinical practice guidelines implementation: a medical app for pediatric acute gastroenteritis\\nYear: 2013\\n\\nAbstract: Clinical practice guidelines (CPGs) are systematically developed documents that assist healthcare practitioners in making decisions about appropriate care for specific diseases based on evidence. In this context, acute gastroenteritis (AGE) in pediatrics is a suitable model for guidelines implementation and CPGs are available and very straightforward. Unfortunately, CPGs for AGE are poorly applied and most children receive not needed interventions. Mobile learning is a collaborative form of learning that can be used as a strategy of implementation for CPGs, for its portability and spreading capacity at a reasonable cost. In this paper we describe the development of a smartphone/tablet application for physicians providing guided decision making and carrying guidelines content about pediatric AGE in order to implement the pivotal recommendations from the CPGs and to foster their diffusion.\",\n \"Title: SmARTweet: A Location-Based Smart Application for Exhibits and Museums\\nYear: 2013\\n\\nAbstract: In this paper, we present \\\"Smartweed\\\", a Locationbased application developed within DATABENC, a high technology district for Cultural Heritage management. In particular, the project aims at exploiting several location-based services and technologies to realize a smart multimedia guide system able to detect the closest artworks to an user, make them able to \\\"tweet\\\" and \\\"talk\\\" during tourists' visit and capable of automatically telling their stories using multimedia facilities. Moreover, we have deployed and tested the installation of some sensors that, using Wi-Fi technology, allow to the users' mobile devices to detect the closest artwork in a museum environment. Once an artwork has been detected, the related identifier is retrieved and a multimedia story is delivered to user by means of proper multimedia delivery and user-profiling techniques, in order to facilitate and make more stimulating the visit. The artworks detection was performed by a localization algorithm that we designed and tested in our laboratory rooms. As case of study, we show an example of \\\"tweeting and talking artworks\\\" as a location-based application of a sculptures' art exhibition within the Maschio Angioino castle, in Naples - Italy.\",\n \"Title: The C@Rolin@ Software A System For Monitoring Skills Development Of Children With Down Syndrome\\nYear: 2011\\n\\nAbstract: The study of medical protocols for monitoring and analyzing the cognitive development of children with disabilities is a fundamental research area. In this context, a well established curriculum-based assessment is the Carolina Curriculum for Infants and Toddlers with Special Needs(CCITSN). This is a suitable curriculum for early intervention programs, where sequenced items data collection and analysis allow for monitoring, incremental program change, and recognition of areas of relative strength and weakness in children with mild, moderate, or severe disabilities.This paper describes the design and the development of an information system based on a client-server software application, named C@rolin@, which carries out all CCITSN abilities and more, for the monitoring and the analysis of data coming from a medical protocol for children with the Down syndrome. In particular, by means of user-friendly graphic interfaces, the C@rolin@ software helps users to add, modify, recover, and analyze data, to watch singular and aggregate data via customized reports, as well as to interpolate data among children to determine or prevent specific behaviors.\",\n \"Title: A Regularized Mri Image Reconstruction Based On Hessian Penalty Term On Cpu/Gpu Systems\\nYear: 2013\\n\\nAbstract: In this paper we investigate an inverse reconstruction problem of Magnetic Resonance Imaging with few acquired body scanner samples. The missing information in the Fourier domain causes image artefacts, therefore iterative computationally expensive recovery techniques are needed. We propose a regularization approach based on second order derivative of both simulated and real images with highly undersampled data, obtaining a good reconstruction accuracy. Moreover, an accelerated regularization algorithm, by using a projection technique combined with an implementation on Graphics Processing Unit (GPU) computing environment, is presented. The numerical experiments give clinically-feasible reconstruction runtimes with an increase in speed and accuracy of the MRI dataset reconstructions.\",\n \"Title: A Novel Challenge into Multimedia Cultural Heritage: An Integrated Approach to Support Cultural Information Enrichment\\nYear: 2013\\n\\nAbstract: In this paper we focus on the issue of pervasive applications and service development supporting cultural heritage. Modeling and creation of unified, structured and extensible artwork badge, here referred as booklet, represents the base to exploit such structured information as the building block for innovative amazing and more involving multimedia fruition paths in the cultural heritage domains. So we propose an integrated approach to cover multiple issues represented by: (i) enriching the collection of available information about artworks, from domain experts and well assessed sources, (ii) structuring of such heterogeneous information in a unified model, (iii) stimulating into no expert and, more generally, common people the attitude to take care and valorize cultural richness and goods, by the way of involving them to actively contribute to the composition and enrichment process of the artworks information and of proposing innovative and pervasive ways to enjoy cultural goods, even through the means of social networks channels and explicit feedback system. Common people's and domain experts' precious contributions have to be verified, merged, homogenized and structured to become knowledge, in the form of a booklet. To collect such data, there's the need to provide proper tools to people and new kinds of presentation and fruition experiences. In this perspective, we propose a prototypal framework architecture, organized as a Service Oriented Architecture (SOA) and focused on the modeling of knowledge and on the orchestration of a set of software services involved in the verification, merging and homogenization of different kinds of retrieved data.\",\n \"Title: 3D data denoising via Nonlocal Means filter by using parallel GPU strategies.\\nYear: 2014\\n\\nAbstract: Nonlocal Means (NLM) algorithm is widely considered as a state-of-the-art denoising filter in many research fields. Its high computational complexity leads researchers to the development of parallel programming approaches and the use of massively parallel architectures such as the GPUs. In the recent years, the GPU devices had led to achieving reasonable running times by filtering, slice-by-slice, and 3D datasets with a 2D NLM algorithm. In our approach we design and implement a fully 3D NonLocal Means parallel approach, adopting different algorithm mapping strategies on GPU architecture and multi-GPU framework, in order to demonstrate its high applicability and scalability. The experimental results we obtained encourage the usability of our approach in a large spectrum of applicative scenarios such as magnetic resonance imaging (MRI) or video sequence denoising.\",\n \"Title: A location-based smart application applied to cultural heritage environments.\\nYear: 2014\\n\\nAbstract: In this paper, we present a Location-based application developed within DATABENC, a high technology district for Cultural Heritage management. In particular, the project aims at exploiting several location-based services and technologies in order to realize a smart multimedia guide system. This system is able to detect the closest artworks to an user, make these artworks able to tweet and talk during users visit and capable of automatically telling their stories using multimedia facilities. Several experiments are performend in our laboratory by means of the installation of some sensors that, using Wi-Fi technology, allow the users mobile devices to detect the closest artwork as in a museum environment. The cultural items detection was performed by a localization algorithm designed and tested in our laboratory environment. As case of study, we show an example of tweeting and talking artworks as a location-based application of a sculptures art exhibition within the Maschio Angioino castle, in Naples Italy.\",\n \"Title: SmaCH: A Framework for Smart Cultural Heritage Spaces\\nYear: 2014\\n\\nAbstract: Cultural Heritage represents a world wide resource of inestimable value, attracting millions of visitors every year to monuments, museums and art exhibitions. A fundamental aspect of this resource is represented by its fruition and promotion. Indeed, to achieve a fruition of a cultural space that is sustainable, it is necessary to realize smart solutions for visitors' interaction to enrich their visiting experience. In this paper we present a service-oriented framework aimed to transform indoor Cultural Heritage sites in smart environments, which enforces a set of multimedia and communication services to support the changing of these spaces in an indispensable dynamic instrument for knowledge, fruition and growth for all the people. Following the Internet of Things paradigm, the proposed framework relies on the integration of a Wireless Sensor Network (WSN) with Wi-Fi and Bluetooth technologies to identify, locate and support visitors equipped with their own mobile devices.\",\n \"Title: Designing a Smart Museum: When Cultural Heritage Joins IoT\\nYear: 2014\\n\\nAbstract: The adoption of the Internet of Things (IoT) paradigm constitutes the basic building block to progress towards unified ICT platforms for a variety of applications within the large framework of the smart cities. Unfortunately, designing a general architecture for IoT is still a very complex challenge, since in such system may be involved several devices, link layer technologies and services. Cultural Heritage represents a worldwide resource of inestimable value and it gains more and more importance when embedded into the digital ecosystem of a smart city. In this paper we focus specifically to design a IoT architecture that is able to support the designing of a smart museum, a static cultural space that becomes intelligent thanks to the definition of an innovative model of sensors and services. Furthermore, the paper will present and discuss a real case of study, placed in a temporary art exhibition of sculptures in the Maschio Angioino Castle, located in Naples, Italy.\",\n \"Title: Smart environments and Cultural Heritage: a novel approach to create intelligent cultural spaces\\nYear: 2015\\n\\nAbstract: AbstractThe relationship between cultural heritage domain and new technologies has always been complex, dialectical and often inspired by the human desire to induce these spaces not created for that purpose, to pursue technological trends, eventually offering to the end-users devices and innovative technologies that could become a ‘dead weight’ during their cultural experiences. However, by means of innovative technological applications and location-based services it is possible to shorten the distance between cultural spaces and their visitors, nowadays determined by the purely aesthetic and essentially passive fruition of cultural objects. This paper presents the design and implementation of a novel multipurpose system for creating single smart spaces , a new concept of intelligent environment, that relies on innovative sensors board named smart crickets and an ad hoc proximity strategy; by following the Internet of Things paradigm the proposed system is able to transform a cultural space in a smart cultural environment to enhance the enjoyment and satisfaction of the involved people. To assess the effectiveness of our solution, we have experienced two real case studies, the first one situated within an art exhibition indoor, and the second one concerning an historical building outdoor. In this way, technology can become a mediator between visitors and fruition, an instrument of connection between people, objects and spaces to create new social, economic and cultural opportunities.\",\n \"Title: Cultural Heritage and Social Pulse: A Semantic Approach for CH Sensitivity Discovery in Social Media Data\\nYear: 2016\\n\\nAbstract: The demand for real-time business intelligence and the popularity of social media offer room for synthesis. A recent topic of interest in such perspective is Cultural Heritage, as empirically evidenced, in 2015, by Twitter introduction of the hashtag #culturalheritage. The opportunities offered by linking both concepts are acknowledged in the recent scientific literature, but a relative underexposure of quantitative studies devoted to assess the potential and effectiveness of social pulses and activities for supporting organizations promoting Cultural Heritage was recorded. In this work a data driven approach is proposed. Basing on the effective employment of domain specific and general ontologies, it aims to identify a set of Key Performance Indicators (KPIs) for quantitative estimation of Cultural Heritage Sensitivity as expressed by social network users. Quantitative analysis of huge datasets of tweets, combining Natural Language Processing (NLP), semantic technologies, geo-referencing and temporal analysis, and issued in a long period of time from geographical areas of Italy having different densities of CH resources, were performed. Examples of computed measures for characterizing people's interest and sensitivity into CH subjects, are geographical density of CH resources and temporal proximity to CHrelated events. Obtained results encourage a Business-Intelligence approach.\",\n \"Title: SMuNe: A Smart Multisensor Network Based on Embedded Systems in IoT Environment.\\nYear: 2015\\n\\nAbstract: Nowadays embedded systems have reached a great level of maturity and diffusion thanks to their small size, low power consumption, large connectivity and variety of application in everyday contexts. These systems, if properly structured and configured, can significantly increase the smartness of the environments where they are deployed, monitoring and continuously collecting data to be processed and elaborated. Such operations can be correctly executed, especially in large locations, if several embedded systems nodes are deployed under the design of an intelligent network. This paper presents SMuNe, a Smart Multisensor Network based on the BeableBone Black platform, a complete open hardware and software embedded computer, the challenge is to create a multi-purpose hierarchical network composed by smart nodes able to gain and manage heterogeneous data and spaces according to the Internet of Things (IoT) paradigm. As a proof of the effectiveness of SMuNe we conducted an experimentation within the Cultural Heritage domain, in detail we deployed SMuNe within a sculptures exhibition named \\\\\\\"The Beauty or the Truth\\\\\\\" in the monumental site of San Domenico Maggiore in Naples, Italy.\",\n \"Title: Modelling the context evolution in Cultural Heritage domain: A graph approach\\nYear: 2014\\n\\nAbstract: Nowadays, smart and pervasive environments are characterized by a large number of devices and related services offered to users. Providing the most appropriate services according to users behaviour and preferences is still a challenge and strongly depends on the user's current context. How it is well known, the context is often rich of data and very dynamic, and the users aim to continuously receive information about contextualised services. In this scenario, Cultural Heritage represents a domain where exchanged and produced data can be opportunely exploited by a set of applications and services in order to make the environment smart. This paper proposes a novel approach to represent and manage the evolution of context instances driven by events adopting a graph structure. As a case study, we propose an example of context evolution in an art exhibition within the Maschio Angioino castle, in Naples (Italy).\",\n \"Title: The TrUST Project: Improving the Fruition of Historical Centres through Smart Objects\\nYear: 2015\\n\\nAbstract: In the last few years, the Internet of Things (IoT) is evolving through a new definition of this paradigm describing a system of cooperating Smart Objects (SOs). An SO can be defined as a physical digital object augmented with sensing, processing, storing and networking capabilities. The key role of such objects resides in the capabilities they have to make physical environments intel- ligent so as to provide novel services to people. Cultural Heritage domain and in particular its fruition and enjoyment perspectives can profitably benefits of such technologies since it characterize a domain where different aspects have to be considered: people enjoyment, cultural items fruition, valorisation and tutelage of spaces and artworks. In this paper we present an ongoing project, named (TrUST - Transport with Ubiquiotus and Smart Technologies) and developed within DATABENC, a high technology district for Cultural Heritage management, in collaboration with the Mobility Transport Company (ANM) of Naples. The project exploits the Internet of Things technologies in order to enable a novel fruition metaphor inside the transport coaches. Deploying a SO with GPS and WiFi capabilities, users can enjoy of multimedia content about the cultural heritage that surrounds them during a trip.\",\n \"Title: An Associative Engines Based Approach Supporting Collaborative Analytics in the Internet of Cultural Things.\\nYear: 2017\\n\\nAbstract: Abstract In this paper we illustrate an integrated approach combining Business Intelligence, Big Data and Internet of Things (IoT), which is applied to information resources including structured and unstructured contents, Geo-Spatial and Social Network data, Multimedia (MM), multiple domain vocabularies, classifiers and ontologies. This is implemented in an information system which exploits Associative in-memory technologies in the context of Cloud Computing, as well as Semantic technologies for merging and analyzing information coming from heterogeneous sources. The primary aim is supporting Cultural Heritage Asset crowdsourcing, promotion, publication, management and usage. We describe and discuss, in particular, the application of this system for the analysis of behavior and interest of visitors in different types of populations and visits: on-site/ad-hoc (exhibitions, museums, cultural events) and territorial (historical downtown, archaeological or other touristic areas and routes including cultural resources). In this way it will be possible to provide a common ICT infrastructure and a set of advanced services for all types of subjects interested in the Cultural Heritage domain. The results of the experimentation encourage a Business Intelligence approach which is suitable for both nonprofit, research and business oriented organizations.\",\n \"Title: A smart system to manage the context evolution in the Cultural Heritage domain.\\nYear: 2016\\n\\nAbstract: Model the context evolution by means of a graph approach.Design a Context Evolution System (CES) to manage the context evolution and the consequently tailoring of data and services.Improve user experience by means of this kind of system.Our apporach is suitable within the Cultural Heritage domain. Nowadays intelligent and pervasive environments are characterized by a great number of devices and sensors that develop continuously and capture enormous amounts of data. Designing a context-aware system able to provide the most tailored services to users according to their behaviors, preferences and needs is still a research challenge. In such environments, although the context is very complex, dynamic and full of data captured and produced, users aspire to automatically receive contextualized services. The Cultural Heritage domain represents a domain where exchanged and produced data can be opportunely exploited by a set of applications and services in order to transform a static space into a smart environment. In this perspective, this paper presents a context-aware system named Context Evolution System (CES) able to represent and manage the evolution of the context through its instances; such an evolution is driven by occurring events and opportunely modeled by a graph structure. To assess the proposed solution, a Cultural Heritage case study of a real temporary art exhibition named the Beauty or the Truth and located in Naples (Italy) is presented and discussed.\",\n \"Title: Sensitivity Mining in Social Pulses to Address Cultural Heritage Competitive Intelligence\\nYear: 2016\\n\\nAbstract: AbstractThe remarkable opportunities of discovering interesting knowledge from Big Data can be exploited in the Cultural Heritage CH domain, where Social Data Mining could advantage cultural organizations and operators with strategical elements for enjoying and attracting and enjoy visitors, as well as to support knowledge sharing and diffusion processes. A challenging and profitable direction may be combining Social Media Pulses Mining with Business Intelligence, to reveal the underlying key performance indicators, so leading to a 'competitive intelligence' whose application well fits with CH. The main contribution of the proposed research is the application of a Multidimensional Text Mining over multiple dimensions for social media pulses analysis. A set of exploratory studies were performed on textual messages Twitter to explore multiple kind of relations between terms, their compliance with CH, and finally estimating the Social Sensitivity Indicator to this domain and its polarity. Advanced technologies for Big Data processing were exploited.\",\n \"Title: A Service Oriented Framework for Analysing Social Network Activities.\\nYear: 2016\\n\\nAbstract: Analysing and monitoring Social Networking activities raise multiple challenges for the evolution of Service Oriented Systems Engineering. This is particularly evident for event detection in social networks and, more in general, for large-scale Social Analytics, which require continuous processing of data. In this paper we present a service oriented framework exploring effective ways to leverage the opportunities coming from innovations and evolutions in computational power, storage, and infrastructures, with particular focus on modern architectures including in-memory database technology, in-database computation, massive parallel processing, Open Data Services, and scalability with multi-node clusters in Cloud. A prototype of this system was experimented in the contest of a specific kind of social event, an art exhibition of sculptures, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.\",\n \"Title: A novel approach for automatic text analysis and generation for the cultural heritage domain.\\nYear: 2017\\n\\nAbstract: Knowledge is information that has been contextualised in a certain domain, to be used or applied. It represents the basic core of our Cultural Heritage and Natural Language provides us with prime versatile means of construing experience at multiple levels of organization. The natural language generation field consists in the creation of texts providing information contained in other kind of sources (numerical data, graphics, taxonomies and ontologies or even other texts), with the aim of making such texts indistinguishable, as far as possible, from those created by humans. On the other hand, the knowledge extraction, basing on text mining and text analysis tasks, as examples of the many applications born from computational linguistic, provides summarization, categorization, topics extractions from textual resources using linguistic concepts, which deal with the imprecision and ambiguity of human language. This paper presents a research activity focused on exploring and scientifically describing knowledge structure and organization involved in textual resources' generation. Thus, a novel multidimensional model for the representation of conceptual knowledge, is proposed. Furthermore, a real case study in the Cultural Heritage domain is described to demonstrate the effectiveness and the feasibility of the proposed model and approach.\",\n \"Title: A location-based IoT platform supporting the cultural heritage domain.\\nYear: 2017\\n\\nAbstract: The Cultural Heritage domain is a global resource able to gain more and more importance and value because it becomes research field characterized by many aspects to be studied such as its enjoyment and promotion. In this paper, we present the design and the implementation of an intelligent Internet of Things (IoT) platform supporting the Cultural Heritage domain. In details, the objective of the proposed platform is to create intelligent solutions and services to enhance the visitors' interaction with cultural objects. To perform this research task, the platform relies on ubiquitous and IoT applications that can represent a suitable solution for improving visitors' experience when inside a museum or a temporary art exhibition. The IoT paradigm applied to the Cultural Heritage domain has the main purpose to transform a static cultural space into an intelligent environment enforcing a set of proximity-based and multimedia services. To assess our methodology, we realize a real case study during an art event in Naples, Italy.\",\n \"Title: Social recommendation service for cultural heritage.\\nYear: 2017\\n\\nAbstract: Cultural heritage is a domain in which new technologies and services have a special impact on people approach to its spaces. Technologies are changing the role of such spaces, allowing a more in-depth knowledge diffusion and social interactions. Static places become dynamic cultural environments in which people can discover and share new knowledge. Nowadays, cultural heritage is approaching to a new digital era in which people become active elements, as recipients of the actions ensuring the sustainability of such heritage, both moneywise but also simply as the perceived quality of life. In this perspective, this paper presents a novel recommender system to individual and people group in order to create a social recommendation service for cultural ICT applications. As key aspect of the presented work, we introduce a method for discovering and exploiting social affinity between users based on artwork features and user experience. In addition, we propose an architecture of the recommender system related with the affinity and discuss the architecture in terms of sparsity, group recommendation, and sustainability.\",\n \"Title: IoT-based collaborative reputation system for associating visitors and artworks in a cultural scenario.\\nYear: 2017\\n\\nAbstract: We design a CRS to establish the people reputation within Cultural spaces.The system is able to classify visitor behaviours.Our approach is suitable for both nonprofit and business oriented organizations. In this paper, starting from a comprehensive mathematical model of a Collaborative Reputation Systems (CRSes), we present a research study within the Cultural Heritage domain. The main goal of this study has been the evaluation and classification of the visitors behaviour during a cultural event. By means of mobile technological instruments, opportunely deployed within the environment, it is possible to collect data representing the knowledge to be inferred and give a reliable rate for both visitors and exposed artworks. Discussed results, confirm the reliability and the usefulness of CRSes for deeply understand dynamics related to people visiting styles.\",\n \"Title: The Internet of Things Supporting Context-Aware Computing: A Cultural Heritage Case Study.\\nYear: 2017\\n\\nAbstract: We're currently shifting from the Information Age to the Intelligence Age. The Intelligence Age will be characterized by autonomous communication between intelligent devices that are sensitive to a person's presence and respond by performing a specific task that enhances that person's lifestyle. In this perspective, the Internet of Things envisages a plethora of heterogeneous objects interacting with people and the physical environment. Things are able to sense a user's presence, movement and behaviour, analyse that data in order to learn about that user, and then make an intelligent decision to perform a task based on the data. Context-aware computing has proven to be successful in understanding data captured by sensors. In this paper, we present a Internet of Things (IoT) context-aware system and its application in the Cultural Heritage domain. Cultural Heritage is a domain where the widespread diffusion of ICT technology and sensors, within its spaces like museums, art exhibition, etc., can strongly enhance the quality of the offered services and subsequently create a Smart Cultural Environment.\",\n \"Title: The Internet of Cultural Things: Towards a Smart Cultural Heritage\\nYear: 2016\\n\\nAbstract: Cultural Heritage (CH) represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments, museums, exhibitions and historical centres. Fundamental aspects of this resource to be enhanced are the promotion, the tutelage, the safeguard and people enjoyment. The Internet of Things (IoT) paradigm applied to the Cultural Heritage domain is a novel concept integrating intelligent objects, sensors, services and applications within static cultural places. The objective is to transform these spaces into Smart Cultural Heritage environments. The Internet of Cultural Things is an emerging discipline aims to design a novel fruition, tutelage and promotion models of the Cultural Heritage in the worldwide. The designed and developed IoT systems will be able to be pervasive and ubiquitous with the definitive goal of rethinking CH in terms of sustainability, enrichment and valorisation towards the future generations. Furthermore, the Internet of Cultural Things can provide greater efficiency in the coordination of processes and facilitate the development of new activities that can generate economic returns.\",\n \"Title: Designing a Service Oriented System for social analytics.\\nYear: 2016\\n\\nAbstract: Event detection in social networks and, more in general, for large-scale Social Analytics, requires continuous monitoring and processing of huge volumes of data. In this paper we explored effective ways to leverage the opportunities coming from innovations and evolutions in computational power, storage, and infrastructures, with particular focus on modern architectures. In particular, we position a specific core technology and cloud platform adopted in our research with respect to micro-services. Furthermore, we demonstrate the application of some of its capabilities for performing data-intensive computations and implementing services in a real case of social analytics. A prototype of this system was experimented in the contest of a specific kind of social event, an art exhibition of sculptures, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.\",\n \"Title: Understanding Customer Experience Diffusion on Social Networking Services by Big Data Analytics.\\nYear: 2017\\n\\nAbstract: Social networking services (e.g., Facebook and Twitter) are playing a significant role of interacting with customers. In particular, most of businesses are trying to exploit such social networking services for more profit, since it has dramatically become an information carrier for customers who are disseminating latest information about products and services. Thus, this study examines how information shared by companies is distributed and what the important factors in understanding information dissemination are. More importantly, this study classifies the types of tweets posted by a company and then to investigate the effect of these types of tweets on diffusion. By using content analysis, this study defined three types, which are ) information provision (IF), ) advertisement (AD), and ) both (IFAD), with 8 specific concepts. These results indicate that the differences are significant for all three types of information content. It shows that companies can spread information more quickly by providing the IFAD type rather than the AD type.\",\n \"Title: Spatio-Temporal Contextualization of Queries for Microtexts in Social Media: Mathematical Modeling.\\nYear: 2017\\n\\nAbstract: In this paper, we present our ongoing project on query contextualization by integrating all possible IoT-based data sources. Most importantly, mobile users are regarded as the IoT sensors which can be the textual data sources with spatio-temporal contexts. Given a large amount of text streams, it has been difficult for the traditional information retrieval systems to conduct the searching tasks. The goal of this work is i) to understand and process microtexts in social media (e.g., Twitter and Facebook), and ii) to reformulate the queries for searching for relevant microtexts in these social media.\",\n \"Title: Remarks on a computational estimator for the barrier option pricing in an IoT scenario.\\nYear: 2017\\n\\nAbstract: The importance of derivatives in financial markets has known an exponential growth in the last decades, especially in risk management and speculation fields: this explains researchers’ interest in answering questions about this kind of contracts. In particular, in this paper we restrict our attention on European vanilla and barrier options, and we propose a statistical procedure to solve efficiently the problem of determining the no arbitrage price of this type of derivatives in an IoT context: starting form an Internet of Things (IoT) data flow, an IoT system takes information from several sources and stores it into a suitable database; this information is used in our estimation problem. Our scheme is based on some strong assumptions about the market model, in particular the completeness of the market, the log-normality of the underlying asset with a constant volatility.\",\n \"Title: Control frameworks in network emulation testbeds: A survey.\\nYear: 2017\\n\\nAbstract: Abstract The network emulation testbed is a promising research area because it provides a platform to fulfill testing requirements, creating emulated environments for conducting experiments. Through such testbeds, heterogeneous resources can be well controlled as emulated environment, and new ideas can be verified in the environment without interfering the real world. Thus, it can be used to reduce the time of the developers for conducting experiment to explore new inventions. Various kinds of network emulation testbed have been around for years, and it can be expected that more testbeds will emerge. To provide an integrated perspective of network emulation testbed, this paper surveys the issues associated in developing network emulation testbeds, including the state-of-the-art of architecture, the interoperability of orchestrating resources, and the way of managing components. Several wide-area, geographically distributed and large-scale network testbeds have been reviewed and discussed. Finally, critical research findings, open issues, and possible future research directions have also been provided.\",\n \"Title: Smach: An Infrastructure For Smart Cultural Heritage Environments\\nYear: 2017\\n\\nAbstract: Cultural heritage represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments and museums. Fundamental aspects of this resource to be investigated are its promotion and people enjoyment. Indeed, to achieve an enjoyment of a cultural space that is attractive, it is necessary to realise ubiquitous solutions for users' interaction to enrich their visiting experience and improve the knowledge transmission process. Thanks to ICT technologies, it is possible to shorten the distance between a cultural site and its visitors, and re-establish to them the truly educational role which provides the opportunity to produce new experiences of knowledge transmission. In this paper, we present a service-oriented infrastructure aimed to transform cultural heritage sites into smart environments. Following the Internet of Things paradigm, the proposed infrastructure relies on the integration of a wireless sensor network (WSN) with Wi-Fi and Bluetooth technologies to identify, locate and support users.\",\n \"Title: S-InTime: A social cloud analytical service oriented system.\\nYear: 2018\\n\\nAbstract: Social Networking activities raise multiple challenges for the evolution of Service Oriented Systems Engineering. The purpose of this research work is to demonstrate how a specific core technology and cloud platform with micro-services can be designed and used for performing data-intensive computations and implementing services in a real case of social analytics. In detail, we face the challenges of real-time data-intensive processing with the systematic application of in-memory view-based information modeling & computation, which is based on different types of non-materialized views without pre-aggregation of data. Finally, our study presents and compares design alternatives for these mappings, and demonstrates their effective application for implementing a large set of social analytics service types, with particular reference to the case of streaming sources of twitter data. A prototype of this system was experimented in the contest of a specific kind of social event, a permanent exhibition of Artworks, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms.\",\n \"Title: Editorial for FGCS special issue: The Internet of Cultural Things: Towards a Smart Cultural heritage.\\nYear: 2018\\n\\nAbstract: Cultural Heritage (CH) represents a worldwide resource of inestimable value, attracting millions of visitors every year to monuments, museums, events and exhibitions. Fundamental aspects of this resource to be enhanced are the promotion, the tutelage, the safeguard and people enjoyment.\",\n \"Title: Centrality in heterogeneous social networks for lurkers detection: An approach based on hypergraphs.\\nYear: 2018\\n\\nAbstract: Nowadays, social networks provide users an interactive platform to create and share heterogeneous content for a lot of different purposes (eg, to comment events and facts, and express and share personal opinions on specific topics), allowing millions of individuals to create online profiles and share personal information with vast networks known and sometimes also unknown people. Knowledge about users, content, and relationships in a social network may be used for an adversary attack of some victims easily. Although a number of works have been done for data privacy preservation on relational data, they cannot be applied in social networks and in general for big data analytics. In this paper, we first propose a novel data model that integrates and combines information on users belonging to 1 or more heterogeneous online social networks, together with the content that is generated, shared, and used within the related environments, using an hypergraph data structure; then we implemented the most diffused centrality measures and also introduced a new centrality measurebased on the concept of neighborhood among usersthat may be efficiently applied for a number of data privacy issues, such as lurkers and neighborhood attack prevention, especially in interest-based social networks. Some experiments using the Yelp dataset are discussed.\",\n \"Title: A Framework for Assessing Reusability Using Package Cohesion Measure in Aspect Oriented Systems.\\nYear: 2018\\n\\nAbstract: Due to better modularization of crosscutting concerns, the Aspect oriented programming approach enhances the quality of the system as it results in less complex and more readable implementation of the system. As the software applications grow in size and complexity, they require some kind of high level organization. For high level organization of software system, packages are required. A lot of work has been carried out for measuring cohesion in Aspect Oriented Systems (AOS) at class level but very less research has been done for designing package level cohesion metric. Package cohesion metrics plays an important role in analyzing quality of software at package level. According to object oriented design principle, a good software design must have high cohesion with high reusability. Thus a relationship must therefore exist between cohesion and reusability. Number of attempts has been made to evaluate effect of cohesion on external attributes but at class level only. Impact of package level cohesion metrics on reusability for AOS is not yet explored. (a) To implement the proposed package cohesion measure, PCohA, on AspectJ sample packages, (b) to theoretically validate the proposed measure and (c) to find the impact of package cohesion on measuring reusability for AOS. Theoretical validation has been done by proving its validity on four theorems given by Briand et al. For finding the impact of proposed measure on external attributes, correlation has been found between package cohesion, PCohA, and external attribute—reusability. After theoretical validation, it has been proved that the proposed measure is suitable for measuring cohesion at package level. Correlation between package cohesion metric (PCohA) and reusability is calculated by using Karl Pearson Product Moment correlation. The computed values show a strong positive relation between PCohA and Reusability. The proposed package cohesion measure is found to be a useful indicator of external quality factors such as reusability. The proposed metric is also established as a better predictor of code reusability than the existing cohesion measures. The work discussed in this paper can be used for designing high quality software by developing new package level metrics for other quality attributes such as maintainability, changeability etc. as a future work.\",\n \"Title: A GPU Implementation of OLPCA Method in Hybrid Environment.\\nYear: 2018\\n\\nAbstract: Sophisticated denoising algorithms are used to improve image quality in the Magnetic Resonance Imaging field. Of course, better results are obtained by implementing computationally expensive schemes. In this paper, we consider the Overcomplete Local Principal Component Analysis (OLPCA) method for image denoising and its main issues. More in detail, we investigated the impact of the Singular Value Decomposition on the OLPCA algorithm and its high computational cost. Moreover, we propose a fine-to-coarse parallelization strategy in order to exploit a parallel hybrid architecture and we implement a multilevel parallel software as a smart combination between codes using NVIDIA cuBLAS library for Graphic Processor Units (GPUs) and the standard Message Passing Interface library for cluster programming. Experimental results show improvements in terms of execution time with a promising speed up with respect to the CPU and our old GPU versions.\",\n \"Title: A (Multi) Gpu Iterative Reconstruction Algorithm Based On Hessian Penalty Term For Sparse Mri\\nYear: 2018\\n\\nAbstract: A recent trend in the Magnetic Resonance Imaging (MRI) research field is to design and adopt machines that are able to acquire undersampled clinical data, reducing the time for which the patient is lying in the body scanner. Unfortunately, the missing information in these undersampled acquired datasets leads to artefacts in the reconstructed image; therefore, computationally expensive image reconstruction techniques are required. In this paper, we present an iterative regularisation strategy with a second-order derivative penalty term for the reconstruction of undersampled image datasets. Moreover, we compare this approach with other constrained minimisation methods, resulting in improved accuracy. Finally, an implementation on a massively parallel architecture environment, a multi Graphics Processing Unit (GPU) system, of the proposed iterative algorithm is presented. The resulting performance gives clinically-feasible reconstruction run times, speed-up and improvements in terms of reconstruction accuracy of the undersampled MRI images.\",\n \"Title: An inverse Bayesian scheme for the denoising of ECG signals.\\nYear: 2018\\n\\nAbstract: The ECG filtering problem is a widely explored research topic. In this paper we propose a novel methodology taking into account some “a priori” information on the signal components that gives significant improvements in the denoising task. Our approach is a modification of recursive filtering (RF) by considering a probabilistic Bayesian framework that is adopted to remove selectively artifacts from the signals without the loss of any crucial medical information on the acquired data. The proposed scheme is very efficient from the computational point of view and this feature makes it ready as a useful tool for application in mobile devices equipped with specific sensors. Finally, numerical experiments have been carried out on real data to assess the advantages of the algorithm.\",\n \"Title: A Robust Features-Based Person Tracker for Overhead Views in Industrial Environment.\\nYear: 2018\\n\\nAbstract: A top view camera having wide range lens installed overhead of the objects contributes greatly toward resolving the tracking problem and also maintains comprehensive visual access of the environment. Video analytics becoming more important to Internet of Things applications including automatic people monitoring and surveillance systems. We followed an approach based on machine learning features-ba...\",\n \"Title: A Perspective On Applications Of In-Memory And Associative Approaches Supporting Cultural Big Data Analytics\\nYear: 2018\\n\\nAbstract: Business intelligence, advanced analytics, big data, in-memory database and associative technologies are actually the key enablers for enhanced business decision making. In this paper, we provide a perspective on applications of in-memory approaches supporting analytics in the field of the cultural heritage applied to information resources including structured and unstructured contents, geo-spatial and social network data, multimedia (MM), multiple domain vocabularies, classifiers and ontologies. The proposed approach has been implemented in an information system exploiting associative in-memory technologies in a cloud context, as well as integrating semantic technologies for merging and analysing information coming from heterogeneous sources. We analyse and describe the application of this system to trace a behavioural and interest profile of users and visitors for cultural events (exhibitions, museums, etc.) and territorial (tourist areas and routes including cultural resources, historical down-town, and archaeological sites). The results of ongoing experimentation encourage a business intelligence approach which is suitable for supporting cultural heritage asset crowdsourcing, promotion, publication, management and usage.\",\n \"Title: Self And Social Network Behaviours Of Users In Cultural Spaces\\nYear: 2018\\n\\nAbstract: Many cultural spaces offer their visitors the use of ICT tools to enhance their visit experience. Data collected within such spaces can be analysed in order to discover hidden information related to visitors' behaviours and needs. In this paper, a computational model inspired by neuroscience simulating the personalised interactions of users with cultural heritage objects is presented. We compare a strengthened validation approach for neural networks based on classification techniques with a novel proposal one, based on clustering strategies. Such approaches allow us to identify natural users' groups in data and to verify the model responses in terms of user interests. Finally, the presented model has been extended to simulate social behaviours in a community, through the sharing of interests and opinions related to cultural heritage assets. This data propagation has been further analysed in order to reproduce applicative scenarios on social networks.\",\n \"Title: Reproducing dynamics related to an Internet of Things framework: A numerical and statistical approach.\\nYear: 2018\\n\\nAbstract: In the Cultural Heritage domain, novel fruition and enjoyment approaches, based on Internet of Things (IoT) paradigm, have the effect to change the way people experiencing cultural spaces, such as museums and exhibitions. Within these environments, a main challenge is to classify and forecast the behaviours of visitors by collecting their movements, choices and needs. In this paper, starting from the design of an IoT system for collecting behavioural data, we propose and discuss a model able to reproduce, and then “predict”, the dynamics related to the interactions of the visitors with the exposed artworks and, in particular, with the available technologies. Generally, collected data are affected by many kinds of errors; to address this issue a powerful statistical method to reproduce the dynamics related to the visiting styles of the spectators is proposed. Numerical experiments on real data have been reported in order to assess the proposed methodology.\",\n \"Title: Implications of deep learning for the automation of design patterns organization.\\nYear: 2018\\n\\nAbstract: Though like other domains such as email filtering, web page classification, sentiment analysis, and author identification, the researchers have employed the text categorization approach to automate organization and selection of design patterns. However, there is a need to bridge the gap between the semantic relationship between design patterns (i.e. Documents) and the features which are used for the organization of design patterns. In this study, we propose an approach by leveraging a powerful deep learning algorithm named Deep Belief Network (DBN) which learns on the semantic representation of documents formulated in the form of feature vectors. We performed a case study in the context of a text categorization based automated system used for the classification and selection of software design patterns. In the case study, we focused on two main research objectives: 1) to empirically investigate the effect of feature sets constructed through the global filter-based feature selection methods besides the proposed approach, and 2) to evaluate the significant improvement in the classification decision (i.e. Pattern organization) of classifiers using the proposed approach. The adjustment of DBN parameters such as a number of hidden layers, nodes and iteration can aid a developer to construct a more illustrative feature set. The experimental promising results suggest the significance of the proposed approach to construct a more representative feature set and improve the classifier’s performance in terms of organization of design patterns.\",\n \"Title: Remarks of Social Data Mining Applications in the Internet of Data.\\nYear: 2018\\n\\nAbstract: Social network analysis attracted interests from both the research and business communities for a strong potential and variety of applications. In addition, this interest has been fuelled by the large success of online social networking sites and the subsequent abundance of social network data produced. A key aspect in this research field is the influence maximization in social networks. In this paper we discuss an overview about the models and the approaches widely used to analyse social networks. In this context, we also discuss data preparation and privacy concerns also considering different kind of approaches based on centrality measures.\",\n \"Title: Serious Games and In-Cloud Data Analytics for the Virtualization and Personalization of Rehabilitation Treatments.\\nYear: 2019\\n\\nAbstract: During the last years, the significant increase in the number of patients in need of rehabilitation has generated an unsustainable economic impact on healthcare systems, implying a reduction in therapeutic supervision and support for each patient. To address this problem, this paper proposes a telerehabilitation system based on serious games and in-cloud data analytics services, in accordance with...\",\n \"Title: SOS: A multimedia recommender System for Online Social networks.\\nYear: 2019\\n\\nAbstract: The use of Online Social Networks has been rapidly increased over the last years. In particular, Social Media Networks allow people to communicate, share, comment and observe different types of multimedia content. This phenomenon produces a huge amount of data showing Big Data features, mainly due to their high change rate, large volume and intrinsic heterogeneity. In this perspective, in the last decade Recommender Systems have been introduced to support the browsing of such data collections, assisting users to find “what they really need” within this ocean of information. In this research work, we propose and describe a novel recommending system for big data applications able to provide recommendations on the base of the interactions among users and the generated multimedia contents in one or more social media networks. The proposed system relies on a “user-centered” approach. An experimental campaign, using data coming from many social media networks, has been performed in order to assess the proposed approach also showing how it can obtain very promising results.\",\n \"Title: Enabling multimedia aware vertical handover Management in Internet of Things based heterogeneous wireless networks.\\nYear: 2017\\n\\nAbstract: Enabling seamless connectivity in Internet of Things (IoT) based heterogeneous wireless networks and pervasive use of smartphones in daily life require high data speed and always-best-connected services. However, providing vertical handover management in heterogeneous wireless networks is a difficult and challenging task. Moreover, various issues are present in the current vertical handover management schemes such as inappropriate handover triggering, high handover delay, wrong network selection, etc. In order to address the aforementioned issues, we propose a generic vertical handover management scheme. Our research is twofold; firstly, the Mobile Node (MN) dynamically checks the data rate required by the applications running on the MN’s device. If the data rate drops below a predefined threshold, the MN initiates the handover. Secondly, the network selection is performed by considering various parameters such as end-to-end delay, jitter, Bit Error Rate, and packet loss. The Artificial Bee Colony (ABC) optimization algorithm uses the above parameters to select the target network with minimum handover delay and time. The proposed scheme is compared with the Simple Additive Weighting (SAW), Weighted Product Method (WPM), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and Fuzzy TOPSIS in context of energy consumption, throughput, average MN’s stay time in a network, handover delay, and handover time. The experimental results show that the proposed vertical handover management scheme outperforms the existing schemes used for similar purpose.\",\n \"Title: A computational method for the European option price in an Internet of Things framework\\nYear: 2020\\n\\nAbstract: In an Internet of Things (IoT) scenario, sensors and devices are able to: (i) extract information from real; (ii) storage them into a database; (iii) use this information for inferring results by the implementation of very efficient algorithms. In this paper we present a computational schema in which, in order to price financial European options, an IoT framework processes data, as financial assets, expiration day, interest rate, strike price. In particular, this procedure involves mathematical tools for the estimation of the volatility and for the calculation of the no arbitrage price. The mathematical model is translated into an algorithm that is implemented in a mobile software. To test its validity, we apply our schema to a real case.\",\n \"Title: Pricing estimation of a barrier option in an IoT scenario\\nYear: 2020\\n\\nAbstract: IoT systems are able to manage very great amount of different types of data. In our paper we propose a mobile app which uses data processed by an IoT framework to estimate the price of a European barrier price. This software is based on an algorithm: in input it receives the values of maturity, strike price, interest rate, barrier level and in output it gives the value of the price. The algorithm implements a mathematical procedure involving numerical and statistical issues, as quadrature formulas and statistical tests. The validity of our methodology is verified by applying it to a real case.\",\n \"Title: Traditional and Deep Learning Approaches to Information and Influence Propagation in Social Networks.\\nYear: 2018\\n\\nAbstract: Social network analysis is an interdisciplinary topic attracting researchers from biology, economics, psychology, and machine learning. It has attracted interests from both the research and business communities for a strong potential and variety of applications. Also, this interest has been fueled by the large success of online social networking sites and the subsequent abundance of social network data produced. An important aspect in this research field is influence maximization in social networks. The goal is to find a set of individuals to be targeted, with the aim to drive social contagion and generate a diffusion cascade. We provide here an overview of the models and approaches used to analyze interaction networks. The challenges this problem introduces are recently being tackled using Deep Learning approaches such as Recurrent Neural Networks (RNNs) which are particularly suited to model sequence inputs.\",\n \"Title: Lessons learned from longitudinal modeling of mobile-equipped visitors in a complex museum\\nYear: 2020\\n\\nAbstract: Cultural sites are evolving toward smart environments, including the notion of hyper-connected museums. In this context, stakeholders of cultural assets need more advanced and comprehensive ICT systems for monitoring and modeling visitors behaviors. In this paper, we discuss the results of a longitudinal research study embracing multiple seasons, in a complex cultural structure including outdoor and indoor attractions, multiple floors and multiple routes for visitors. Here, interactive mobile devices were used for both offering multimedial context-aware assistance to visitors and monitoring services to museum stakeholders. We deeply analyzed the data using an unsupervised classification approach, obtaining a model where the number of distinct user profiles and the number of features were considered not trivial as well as not too complex for museum stakeholders.\\nWe observed that some optimistic expectations about visitor performances were only partially met, devising possible explanations in terms of the different user profiles and features of the model. Finally, we also compared some outcomes from our interactive system with those obtained in another complex cultural structure using a noninvasive monitoring system.\",\n \"Title: General Paradigm of Edge-Based Internet of Things Data Mining for Geohazard Prevention\\nYear: 2021\\n\\nAbstract: Geological hazards (geohazards) are geological processes or phenomena formed under external-induced factors causing losses to human life and property. Geohazards are sudden, cause great harm, and have broad ranges of influence, which bring considerable challenges to geohazard prevention. Monitoring and early warning are the most common strategies to prevent geohazards. With the development of the internet of things (IoT), IoT-based monitoring devices provide rich and fine data, making geohazard monitoring and early warning more accurate and effective. IoT-based monitoring data can be transmitted to a cloud center for processing to provide credible data references for geohazard early warning. However, the massive numbers of IoT devices occupy most resources of the cloud center, which increases the data processing delay. Moreover, limited bandwidth restricts the transmission of large amounts of geohazard monitoring data. Thus, in some cases, cloud computing is not able to meet the real-time requirements of geohazard early warning. Edge computing technology processes data closer to the data source than to the cloud center, which provides the opportunity for the rapid processing of monitoring data. This article presents the general paradigm of edge-based IoT data mining for geohazard prevention, especially monitoring and early warning. The paradigm mainly includes data acquisition, data mining and analysis, and data interpretation. Moreover, a real case is used to illustrate the details of the presented general paradigm. Finally, this article discusses several key problems for the general paradigm of edge-based IoT data mining for geohazard prevention.\",\n \"Title: Optimizing makespan and resource utilization for multi-DNN training in GPU cluster\\nYear: 2021\\n\\nAbstract: Deep neural network (DNN) has been widely applied in many fields of artificial intelligence (AI), gaining great popularity both in industry and academia. Increasing the size of DNN models does dramatically improve the learning accuracy. However, training large-scale DNN models on a single GPU takes unacceptable waiting time. In order to speed up the training process, many distributed deep learning (DL) systems and frameworks have been published and designed for parallel DNN training with multiple GPUs. However, most of the existing studies concentrate only on improving the training speed of a single DNN model under centralized or decentralized systems with synchronous or asynchronous approaches. Few works consider the issue of multi-DNN training on the GPU cluster, which is the joint optimization problem of job scheduling and resource allocation. This paper proposes an optimizing makespan and resource utilization (OMRU) approach to minimize job completion time and improve resource utilization for multi-DNN training in a GPU cluster. Specifically, we first collect the training speed/time data of all DNN models by running a job for one epoch on a different number of GPUs. The OMRU algorithm, integrating job scheduling, resource allocation, and GPU reuse strategies, is then devised to minimize the total job completion time (also called makespan) and improve GPU cluster resource utilization. The linear scaling rule (LSR) is adopted for adjusting the learning rate when a DNN model is trained on multiple GPUs with large minibatch size, which can guarantee model accuracy without the other hyper-parameters tune-up. We implement the OMRU algorithm on the Pytorch with Ring-Allreduce communication architecture and a GPU cluster with 8 nodes, each of which has 4 NVIDIA V100 GPUs. Experimental results on image classification and action recognition show that OMRU achieves a makespan reduction of up to 30% compared to the baseline scheduling algorithms and reach an average of 98.4% and 99.2% resource utilization on image classification and action recognition, respectively, with the state-of-the-art model accuracy.\",\n \"Title: Predictive Analytics for Smart Parking: A Deep Learning Approach in Forecasting of IoT Data\\nYear: 2021\\n\\nAbstract: AbstractNowadays, a sustainable and smart city focuses on energy efficiency and the reduction of polluting emissions through smart mobility projects and initiatives to “sensitize” infrastructure. Smart parking is one of the building blocks of intelligent mobility, innovative mobility that aims to be flexible, integrated, and sustainable and consequently integrated into a Smart City. By using the Internet of Things (IoT) sensors located in the parking areas or the underground car parks in combination with a mobile application, which indicates to citizens the free places in the different areas of the city and guides them toward the chosen parking, it is possible to reduce air pollution and fluidifying noise traffic. In this article, we present and discuss an innovative Deep Learning-based ensemble technique in forecasting the parking space occupancy to reduce the search time for parking and to optimize the flow of cars in particularly congested areas, with an overall positive impact on traffic in urban centres. A genetic algorithm has also been used to optimize predictors parameters. The main goal is to design an intelligent IoT-based service that can predict, in the next few hours, the parking spaces occupancy of a street. The proposed approach has been assessed on a real IoT dataset composed by over than 15M of collected sensor records. Obtained results demonstrate that our method outperforms both single predictors and the widely used strategy of the mean providing inherently robust predictions.\",\n \"Title: Predictive Medicine for Salivary Gland Tumours Identification Through Deep Learning\\nYear: 2022\\n\\nAbstract: Nowadays, predictive medicine begins to become a reality thanks to Artificial Intelligence (AI) which allows, through the processing of huge amounts of data, to identify correlations not perceptible to the human brain. The application of AI in predictive diagnostics is increasingly pervasive; through the use and interpretation of data, the first signs of some diseases (i.e. tumours) can be detected to help physicians make more accurate diagnoses to reduce the errors and develop methods for individualized medical treatment. In this perspective, salivary gland tumours (SGTs) are rare cancers with variable malignancy representing less than 1% of all cancer diagnoses and about 5% of head and neck cancers. The clinical management of SGTs is complicated by a high rate of preclinical diagnostic errors. Today, fine needle aspiration cytology (FNAC) represents the primary diagnostic tool in the hands of clinicians. However, it provides information that about 25% of cases are dubious or inconclusive, complicating therapeutic choices. Thus, finding new tools supporting clinicians to make the right choices in doubtful cases is necessary. This research work presents and discusses a Deep Learning-based framework for automatic segmentation and classification of salivary gland tumours. Furthermore, we propose an explainable segmentation learning approach supporting the effectiveness of the proposed framework through a per-epoch learning process analysis and the attention map mechanism. The proposed framework was evaluated with a collected CT dataset of patients with salivary gland tumours. Experimental results show that our methodology achieves significant scores on both segmentation and classification tasks.\",\n \"Title: Scientific Machine Learning Through Physics–Informed Neural Networks: Where we are and What’s Next\\nYear: 2022\\n\\nAbstract: Physics-Informed Neural Networks (PINN) are neural networks (NNs) that encode model equations, like Partial Differential Equations (PDE), as a component of the neural network itself. PINNs are nowadays used to solve PDEs, fractional equations, integral-differential equations, and stochastic PDEs. This novel methodology has arisen as a multi-task learning framework in which a NN must fit observed data while reducing a PDE residual. This article provides a comprehensive review of the literature on PINNs: while the primary goal of the study was to characterize these networks and their related advantages and disadvantages. The review also attempts to incorporate publications on a broader range of collocation-based physics informed neural networks, which stars form the vanilla PINN, as well as many other variants, such as physics-constrained neural networks (PCNN), variational hp-VPINN, and conservative PINN (CPINN). The study indicates that most research has focused on customizing the PINN through different activation functions, gradient optimization techniques, neural network structures, and loss function structures. Despite the wide range of applications for which PINNs have been used, by demonstrating their ability to be more feasible in some contexts than classical numerical techniques like Finite Element Method (FEM), advancements are still possible, most notably theoretical issues that remain unresolved.\",\n \"Title: An unsupervised learning framework for marketneutral portfolio\\nYear: 2022\\n\\nAbstract: In this paper, we present a portfolio optimization strategy based on a novel approach in assets clustering on the financial background of the Arbitrage Pricing Theory, a well-known multi-factor model. In particular, our aim is to exploit data analysis tools, such as the techniques of features extraction and feature selection, to group assets that exhibit a significant exposition to the same risk factors. Then, we exploit the clustering to build a market-neutral portfolio and, more in general, an investment methodology that takes into account the peculiarities of the specific market. Finally, we apply our methodology in various case studies, discussing the results obtained and highlighting the strengths and the limits of the proposed strategy.\",\n \"Title: Explainable Deep Learning Models on the Diagnosis of Pneumonia\\nYear: 2021\\n\\nAbstract: Pneumonia is a lung infection caused by pathogens such as bacteria and viruses. If the diagnosis is not timely and the treatment cannot be performed in time, it may threaten the life of the patient. Currently, the most common method for the diagnosis of pneumonia is to take chest X-rays and perform manual diagnosis. However, manual diagnosis is less efficient and highly subjective. In this paper, we present a deep learning approach for X-ray image identification of pneumonia and conducts the corresponding explainability. The essential idea is to use the existing pre-trained deep learning model and the Grad-CAM method to construct an explainable deep learning model of pneumonia X-ray image recognition. In the proposed deep learning model, ResNet50 and VGG16 models can achieve higher accuracy after data augmentation. The proposed deep learning model could be applied to the computer-aided diagnosis of pneumonia to achieve efficient detection and diagnosis of pneumonia.\",\n \"Title: Neurocomputing for internet of things: Object recognition and detection strategy\\nYear: 2022\\n\\nAbstract: Modern and new integrated technologies have changed the traditional systems by using more advanced machine learning, artificial intelligence methods, new generation standards, and smart and intelligent devices. The new integrated networks like the Internet of Things (IoT) and 5G standards offer various benefits and services. However, these networks have suffered from multiple object detection, localization, and classification issues. Conventional Neural Networks (CNN) and their variants have been adopted for object detection, classification, and localization in IoT networks to create autonomous devices to make decisions and perform tasks without human intervention and helpful to learn in-depth features. Motivated by these facts, this paper investigates existing object detection and recognition techniques by using CNN models used in IoT networks. This paper presents a Conventional Neural Networks for 5G-Enabled Internet of Things Network (CNN-5GIoT) model for moving and static objects in IoT networks after a detailed comparison. The proposed model is evaluated with existing models to check the accuracy of real-time tracking. The proposed model is more efficient for real-time object detection and recognition than conventional methods.\",\n \"Title: From Artificial Intelligence to Explainable Artificial Intelligence in Industry 4.0: A Survey on What, How, and Where\\nYear: 2022\\n\\nAbstract: Nowadays, Industry 4.0 can be considered a reality, a paradigm integrating modern technologies and innovations. Artificial intelligence (AI) can be considered the leading component of the industrial transformation enabling intelligent machines to execute tasks autonomously such as self-monitoring, interpretation, diagnosis, and analysis. AI-based methodologies (especially machine learning and deep...\",\n \"Title: An Efficient Deep Learning Approach Using Improved Generative Adversarial Networks for Incomplete Information Completion of Self-driving Vehicles\\nYear: 2022\\n\\nAbstract: Autonomous driving is a key technology for intelligent logistics in the Industrial Internet of Things (IIoT). In autonomous driving, the appearance of incomplete point clouds that lose geometric and semantic information is inevitable due to the limitations of occlusion, sensor resolution, and viewing angle when Light Detection And Ranging (LiDAR) is applied. The existence of incomplete point clouds, especially incomplete vehicle point clouds, would lead to a reduction in the accuracy of object detection, traffic alerts, and collision avoidance for autonomous driving vehicles. Existing point cloud completion networks, such as the Point Fractal Network (PF-Net), focus on the accuracy of point cloud completion without considering the efficiency of the inference process, which makes it difficult for them to be deployed for vehicle point cloud repair in autonomous driving. To address this problem, in this paper, we propose an efficient deep learning approach to repair incomplete vehicle point clouds in autonomous driving accurately and efficiently. In the proposed method, an efficient downsampling algorithm that combines incremental sampling and one-time sampling is presented to improve the inference speed of the PF-Net based on Generative Adversarial Network (GAN). To evaluate the performance of the proposed method, a real dataset is used, and autonomous driving scenes are created, where three incomplete vehicle point clouds with 5 different sizes are used for three autonomous driving situations. The improved PF-Net can achieve speedups of over 19x with almost the same accuracy when compared to the original PF-Net. Experimental results demonstrate that the improved PF-Net can be applied to efficiently complete vehicle point clouds in autonomous driving.\",\n \"Title: SWCGAN: Generative Adversarial Network Combining Swin Transformer and CNN for Remote Sensing Image Super-Resolution\\nYear: 2022\\n\\nAbstract: Easy and efficient acquisition of high-resolution remote sensing images is of importance in geographic information systems. Previously, deep neural networks composed of convolutional layers have achieved impressive progress in super-resolution reconstruction. However, the inherent problems of the convolutional layer, including the difficulty of modeling the long-range dependency, limit the performance of these networks on super-resolution reconstruction. To address the abovementioned problems, we propose a generative adversarial network (GAN) by combining the advantages of the swin transformer and convolutional layers, called SWCGAN. It is different from the previous super-resolution models, which are composed of pure convolutional blocks. The essential idea behind the proposed method is to generate high-resolution images by a generator network with a hybrid of convolutional and swin transformer layers and then to use a pure swin transformer discriminator network for adversarial training. In the proposed method, first, we employ a convolutional layer for shallow feature extraction that can be adapted to flexible input sizes; second, we further propose the residual dense swin transformer block to extract deep features for upsampling to generate high-resolution images; and third, we use a simplified swin transformer as the discriminator for adversarial training. To evaluate the performance of the proposed method, we compare the proposed method with other state-of-the-art methods by utilizing the UCMerced benchmark dataset, and we apply the proposed method to real-world remote sensing images. The results demonstrate that the reconstruction performance of the proposed method outperforms other state-of-the-art methods in most metrics.\",\n \"Title: Deep Learning for Secure Communication in Cyber-Physical Systems\\nYear: 2022\\n\\nAbstract: The proliferation of ubiquitous cyber-physical systems (CPSs) that integrate emerging applications of embedded computers and communication technologies into various physical domains exposes them to distinct security challenges. Deep learning (DL) is a promising solution in securing CPS communication by detecting diverse unknown attacks. In this article, we demonstrate the significant potential of DL-based solutions to address the challenges of secure communications in CPSs. First, we outline classic challenges in CPS secure communication. Second, we introduce deep neural networks that are available to address these challenges in CPS secure communication. Third, we demonstrate DL-based solutions for mitigating the challenges in CPS secure communication. Specifically, we discuss the application of DL-based solutions and design two experiments for anomaly detection in CPS secure communication. The remarkable performance of the experimental results demonstrates the effectiveness of DL-based solutions in CPS secure communication.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":63,"string":"63"}}},{"rowIdx":64,"cells":{"question_id":{"kind":"string","value":"Yinong Chen"},"question":{"kind":"string","value":"Generate an abstract for the title \"Robot as a Service in Computing Curriculum\" using the following items: computer science, programming course, enrollment crisis, robotics programming, curriculum improvement."},"answer":{"kind":"string","value":"This paper reports the newly designed first computer science and first programming course CSE101 developed and taught at Arizona State University, and disseminated to many other universities, to address the enrollment crisis as reported by ACM CS Curriculum Committee Review Task Force in 2008. The course teaches the basic computer science and engineering concepts and gives the students the first programming experience through robotics programming. The initial curriculum and the ongoing improvement of the course are presented. The course started with its experiment environment using Microsoft Robotics Developer Studio, Visual Programming Language, and Lego Mind storms robots. The environment is extended to a Web-based programming environment and Intel architecture-based robots."},"correct_answer":{"kind":"string","value":"This paper reports the newly designed first computer science and first programming course CSE101 developed and taught at Arizona State University, and disseminated to many other universities, to address the enrollment crisis as reported by ACM CS Curriculum Committee Review Task Force in 2008. The course teaches the basic computer science and engineering concepts and gives the students the first programming experience through robotics programming. The initial curriculum and the ongoing improvement of the course are presented. The course started with its experiment environment using Microsoft Robotics Developer Studio, Visual Programming Language, and Lego Mind storms robots. The environment is extended to a Web-based programming environment and Intel architecture-based robots."},"documents":{"kind":"list like","value":["Title: Collaborative Learning Using Wiki Web Sites for Computer Science Undergraduate Education: A Case Study\nYear: 2011\n\nAbstract: This paper proposes a collaborative approach to enhancing the student learning experience based on Web 2.0 principles. Specifically, wiki Web sites are used by students for collaboration and for publication of course assignments, which are then shared with the class. Web 2.0 principles include: the Web as platform, harnessing collective intelligence, data are the next Intel Inside, and rich user experiences. Based on a case study in a junior-level undergraduate class, this paper studies a set of six factors with comprehensive grading and evaluation criteria that are critical to make this approach successful. The six factors are knowledge base, motivation, research, social aspects, presentation, and feedback and support. The data collected show that most of the students who participated feel that this approach is exciting and rewarding, and that even some undergraduate students are able to produce original and innovative concepts. The data also show other interesting phenomena with respect to motivation, undergraduate research, and social aspects. Finally, the paper proposes a methodology of conducting a wiki project in a university class using a cyclic constant improvement process.","Title: RTSOA: Real-Time Service-Oriented Architecture\nYear: 2006\n\nAbstract: This paper extends the traditional Service-Oriented Architecture (SOA) to a new Real-Time SOA (RTSOA) and proposes a framework for the new architecture, by providing real-time service modeling, design, code generation, simulation, deployment, execution, orchestration, and management. The concepts, architecture, and enabling technique are studied for Real-time SOA. In addition, an efficient algorithm is derived in the paper to find the optimal composition of real-time services subject to the real-time constraint.","Title: On an Automatic Simulation Environment Customizing Services for Cloud Simulation Center\nYear: 2010\n\nAbstract: Simulation plays an important role in both academic research and industrial development and manufactory. The users’ requirements for simulation are often complex and diverse. It is time consuming and error-prone for users to build different simulation environments manually to conduct their simulation tasks. An Automatic Simulation Environment Customiz卢ing Service for Cloud Simulation Center is presented in this paper to address this problem. The service offers an automatic simulation environment that can customize and configure service requirements of simulation users with high efficiency, flexibility and agility. The system is capable of processing diversified requests dynamically and responding the requests in real-time. The operation and experiments on the prototype system operation and experiment show higher availability, flexibility, and reusability of our method than the traditional simulation environment customizing method.","Title: Distributed Policy Specification and Enforcement in Service-Oriented Business Systems\nYear: 2005\n\nAbstract: Service-Oriented Computing (SOC) and Web Services (WS) provide a flexible computing platform for electronic business and commerce. Introducing policy-based computing to service-oriented business systems adds another dimension of flexibility and security. While service composition and re-composition in service-oriented business systems allow major system reconstruction, policy-based computing can better deal with the small and routine changes of business processing. This paper reports our latest research on integrating policy-based computing into service-oriented business system and discusses its feasibility, benefits and cost. Under this research, we designed a policy specification and enforcement language PSEL for specifying system constraints and business rules. We implemented a runtime environment in which a service-oriented business system can be modeled, analyzed, deployed, and executed with policy enforcement. Automated tools have been developed to facilitate the entire development process. The cost of policy-based computing is experimentally evaluated.","Title: A SOA Based Pipeline System to Deal with Astronomy Telescope Data\nYear: 2006\n\nAbstract: In order to deal with telescope data more systematically and flexibly, this paper proposes a grid middleware pipeline system PMGrid based on serviceoriented architecture (SOA) for efficient telescope data processing. This system allows users to dynamically compose data process application as a Pipeline Virtual Service (PVS) using existing services for their special purposes. Furthermore, the configured PVS has the standard interface as services and can be published in PMGrid system as a single unit of service shared and reused by other users. Grid technologies and Web service technologies are aligned with each other in this system through standard-based interface and protocols. Based on SOA, the PMGrid system can provide not only more telescope data process functions to satisfy users' special purposes, but also more shared public functions. Combing SOA and Grid, the PMGrid system is portable and has advantages in reducing cost and increasing the services utilization. This paper presents the design, analysis, and implementation of the PVS subsystem in the telescope data processing system.","Title: Secondary-diagonal mean transformation Partial Grey Model based on matrix series.\nYear: 2012\n\nAbstract: Grey Model (GM) deals with the systems where certain information about the systems is unknown or incomplete. GM has been successfully used in many engineering areas, including agriculture, energy, economy, and environmental engineering where prediction needs to be made with uncertain factors. Particularly, GM is widely applied in image processing and data filtering. In a GM defined by matrix series, the prediction is made by solving these matrixes through a sequence of matrix operations. To improve the simulation and prediction accuracy of GM matrix solving, a novel secondary-diagonal mean transformation Partial GM (mtP-GM) is developed in this paper. We first defined a mean transformation in the secondary-diagonal direction of the matrix series. We then defined the mtP Accumulating Generation Operation (mtP-AGO) according to the principles of AGO, matrix-AGO (m-AGO), and Partial-AGO (P-AGO). The principles of GM are followed in the modeling process, and grey impact factors of the model are encapsulated in a matrix with m2 unknown elements. Finally, four real data sets with long-running data and multi-stream series are imported for comparing the performance of the developed mtP-GM with several other grey models, such as RGM, dtP-GM, and GM(1,1). The comparison results show that dtP-GM can obtain a better accuracy for periodic data sequences. However, our mtP-GM outperforms the other three models for non-periodic data sequences.","Title: A New SOA Data-Provenance Framework\nYear: 2007\n\nAbstract: Due to the dynamic nature, such as runtime composition and evaluation, it is critical for an SOA system to consider its data provenance, which concerns security, reliability, and integrity of data as it is routed in the system. In a traditional software system, one can focus on the software itself to determine the security, reliability, and integrity; however, in an SOA system, one also needs to consider the origins and routes of data and their impact, i.e., data provenance. This paper first analyzes the unique natures and characteristics of data provenance in an SOA system. Then it proposes a new framework to classify data provenance and collect data in SOA systems. Finally, this paper uses an example to illustrate these concepts and techniques.","Title: Adaptive Web Services Testing\nYear: 2007\n\nAbstract: Web Services (WS) and Service-Oriented Architecture (SOA) present a set of unique testing challenges. As services are distributed, it is necessary to test them using a distributed architecture. Furthermore, as these services may keep on changing, testing needs to be adaptive. This paper proposes an adaptive testing framework which can continuously learn and improve the built-in test strategies. The framework allows different test cases to be selected based on the recent test results. The framework also has a windowing mechanism to evaluate and select test cases. . .","Title: An Index Clustering and Mapping Algorithm for Large Scale Astronomical Data Searching\nYear: 2009\n\nAbstract: For large scale unstructured astronomical data documents, the simple index method often results in high communication cost and slow query processing. Based on the characteristics of domain specific astronomical data and the quantitative tracing and analyzing results, a query terms similarity calculation formula is provided. An index clustering algorithm is designed to generate many small clusters with high term association and small real index size which can be stored into different nodes as a whole. To keep high query locality and reasonable load balancing, a practical index mapping algorithm is proposed to map different logical index clusters onto physical nodes. The simulation results show that the algorithms provided in this paper have good scalability for large scale astronomical data index system. Compared with other methods, different queries can be distributed and located onto smaller number of nodes, so communication cost among different nodes can be reduced significantly and the search efficiency could be well improved.","Title: A simulation cloud monitoring framework and its evaluation model.\nYear: 2013\n\nAbstract: •A framework is provided to design the monitoring system of Simulation Cloud.•Two strategies are provided to reduce monitoring cost and balance load.•An evaluation model is developed to check its feasibility.","Title: Collaborative Web Services Monitoring with Active Service Broker\nYear: 2008\n\nAbstract: This paper proposes a collaborative runtime monitoring framework to enhance the dependability of the software developed in traditional Web services architecture. The enabling mechanism is an active service broker (ASB) architecture which allows the service broker not only to serve as a passive service repository, but also to involve itself in service interactions and thus to play an active role in service execution and monitoring. The ASB communicates remotely with the distributed monitoring agents deployed at the service providerspsila sites. Sensors are instrumented in services at different levels, including the composition level, interface level, and component level. The model-based approach is discussed for automatic sensor generation and runtime enforcement based on service's process model and verification model. A prototype is implemented for the research of the user and science data center of the astronomic satellite system at Tsinghua University.","Title: Verification Framework for Dynamic Collaborative Services in Service-Oriented Architecture\nYear: 2006\n\nAbstract: This paper introduces a dynamic verification framework for collaborative services in Service- Oriented Architecture (SOA). Collaboration plays a critical role in SOA, an effective verification framework for collaboration will greatly reduce the effort for rapid and adaptive service composition and evaluation of applications based on collaborative services. The verification framework provides a service-oriented infrastructure for completeness and consistency analyses, model-checking, simulation, and policy enforcement of process specification based on collaborative services in SOA. The paper presents the concepts, architecture, profiling techniques and illustrative examples that demonstrate the concepts and the techniques.","Title: Teaching Service-Oriented Computing and STEM Topics via Robotic Games\nYear: 2008\n\nAbstract: The ever-increasing functionality and the non-functional constraints that must be satisfied by embedded systems lead to an enormous growth in the complexity at the system level. In this paper we investigate the notion of cognitive complexity and argue ...","Title: Event-driven service-oriented simulation framework\nYear: 2010\n\nAbstract: Service-oriented architecture (SOA) and event-driven architecture (EDA) have received significant attention recently. This paper presents an event-driven service-oriented simulation framework that combines both features of SOA and EDA and it can be used to evaluate embedded applications. The framework allows events, event generators, and event handlers to be published, discovered, and composed to develop an event-driven system, furthermore these can be seamlessly integrated into the existing SOA framework where publishing, discovery, composition and runtime monitoring are key features. This paper also uses PSML (Process Specification and Modeling Language) [1] to specify events. Finally, this paper uses an embedded system to illustrate the framework.","Title: A stepwise optimization algorithm of clustered streaming media servers\nYear: 2009\n\nAbstract: The optimization of Clustered Streaming Media Servers (CSMS), which aims at using as few hardware resources and as cost-effective as possible, while providing satisfactory performance and QoS, has a great impact on the practicability and efficiency of CSMS. Based on the analysis and formulization of critical performance factors of CSMS and the relationship among the performance, QoS, and the costs in CSMS, a stepwise optimization algorithm is developed to solve the optimization problem efficiently. The algorithm is based on an approach that models the optimization problem into a directed acyclic graph and then addresses the complex optimization problem step by step. The algorithm applies a divide and conquer model that not only reduces the complexity of the optimization problem, but also accelerates the optimization process. Progressive information is collected in the process and used in solving the problem. Furthermore, a simulation system of CSMS is necessary for the optimization algorithm to generate the accurate information produced in the entire streaming service process. Thus, we designed and implemented such a simulation system based on the theoretical performance model of CSMS and the parameters measured in practical CSMS testbed. Finally, a case study of the optimization problem is given to demonstrate the process of the algorithm, and an appropriate plan for designing practical CSMS system is illustrated.","Title: Global Software Enterprise: A New Software Constructing Architecture\nYear: 2006\n\nAbstract: Based on current Service-Oriented Architecture (SOA), this paper introduces a consumer-oriented SOA software constructing architecture: the Global Software Enterprise (GSE) architecture. In this architecture, the software construction starts from the consumers' publishing their requirements in the form of application or service specification which they exactly want. The consumer also publishes the expectation for the services the application needs in the form of collaboration specification and test scripts. The service providers then produce services that meet the needs of the applications. This new approach reduces the workload for the consumer and the communication between the consumer and provider. It also extends the design and code sharing, and thus further improves the software productivity.","Title: Performance Simulation of a Dependable Distributed System\nYear: 2001\n\nAbstract: The aim of our research is to develop a distributed system platform that supports a variety of tasks. Currently, we are implementing Internet applications on the system, including a service redirector, firewall, and web applications. These applications have different levels of dependability requirements. Depending on their criticality, a single task may execute on one or more computer nodes. Software-implemented fault-tolerant protocols are used to detect the disagreement among replicas. A reconfiguration protocol is used to identify faulty nodes according to the fault reports from other fault-tolerant protocols and to reallocate their tasks to other working nodes. As a part of the project, this work focuses on the implementation and simulation of the system and the firewall application. Data transfer throughput of the system is measured and analyzed. The results are being used in supporting our development of the overall system.","Title: Automated Model Checking and Testing for Composite Web Services\nYear: 2005\n\nAbstract: Web Services form a new distributed computing paradigm. Collaborative verification and validation are important when Web Services from different vendors are integrated together to carry out a coherent task. This paper presents a new approach to verify Web Services by model checking the process model of OWL-S (Web Ontology Language for Web Services) and to validate them by the test cases automatically generated in the model checking process. We extend the BLAST, a model checker that handles control flow model naturally, to handle the concurrency in OWL-S. We also propose enhancement in OWL-S and PDDL (Planning Domain Definition Language) to facilitate the automated test case generation. Experiments on realistic examples are provided to illustrate the process.","Title: Scheduling Simulation in a Distributed Wireless Embedded System\nYear: 2005\n\nAbstract: The aims of the research are to develop a distributed simulation environment and to investigate techniques that support efficient task-scheduling algorithms in fault-tolerant, real-time, distributed, and wireless embedded systems. Techniques developed include deadline-based real-time scheduling, priority-based scheduling, and redundant resource allocation for fault-tolerant, energy-aware, and signal strength-aware scheduling. A system model is proposed, and a prototype of the distributed simulation environment is implemented. Three scheduling algorithms and sample applications are designed and implemented in the environment. Experiment data are collected for analyzing the effectiveness of the algorithms.","Title: An autonomic provisioning framework for outsourcing data center based on virtual appliances\nYear: 2008\n\nAbstract: As outsourcing data centers emerge to host applications and services from many different organizations, it is critical for data center owners to isolate different applications while dynamically and optimally allocate sharable resources among them. To address this issue, we propose a virtual-appliance-based autonomic resource provisioning framework for large virtualized data centers. We present the architecture of the data center with enriched autonomic features. We define a non-linear constrained optimization model for dynamic resource provisioning and present a novel analytic solution. Key factors, including virtualization overhead and reconfiguration delay, are incorporated into the model. Experimental results based on a prototype demonstrate that the system-level performance has been greatly improved by taking advantage of fine-grained server consolidation, and the whole system exhibits flexible adaptation in failure scenarios. Experiments with the impact of switching delay also show the efficiency of the framework due to significantly reduced provisioning time.","Title: Dynamic Dataflow Driven Service Composition Mechanism for Astronomy Data Processing\nYear: 2007\n\nAbstract: Although some relatively mature products and systems about Dynamic service composition are proposed, their manipulations are mostly not trivial and intuitive for the common users. Therefore, this paper proposes a dataflow driven dynamic service composition architecture aiming at astronomy applications, to simplify the requirements for users to compose a service. The architecture utilizes Dataflow Driven conception to discover an Original Topology Graph, which includes the final composite service with the shortest length and good parallel structure, and uses a Converse Composition algorithm to ascertain the final result quickly. This architecture is applied in the PMGrid prototype for astronomy data processing, and the experiment results show the architecture satisfies the parallelism and asynchrony in distributed system, avoids manual errors, increases the service configuring efficiency, provides the composite service with better structure to increase the executing parallelism, and finally improve the scientific discovery.","Title: Adaptive Testing, Oracle Generation, and Test Case Ranking for Web Services\nYear: 2005\n\nAbstract: Web services and service-oriented architecture are emerging technologies that are changing the way we develop and use computer software. Due to the standardization of web services related description languages and protocols, as well as the open platforms, for the same web service specification, many different implementations can be offered from different service providers. This paper presents an adaptive group testing technique that can test large number web services simultaneously and effectively. Based on a case study, experiments are performed to validate the correctness and effectiveness of the technique.","Title: Architecture Classification for SOA-Based Applications\nYear: 2006\n\nAbstract: The architecture of SOA-based applications is different from traditional software architecture where the architecture is mainly static. The architecture of an SOA-based application is dynamic, i.e., the application may be composed at runtime using existing services. Thus SOA has provided a new direction for software architecture study, where the architecture is determined at runtime and architecture can be dynamically changed at runtime to meet the new software requirements. This paper proposes an architecture classification scheme for SOA-based applications. Using this classification, several wellknown SOA-based applications are reviewed including the architectures proposed and adopted by major computer companies and standard organizations. The architecture classification provides a unified way to evaluate a variety of architectures for SOA-based applications.","Title: Designing a Service-Oriented Computing Course for High Schools\nYear: 2007\n\nAbstract: Service-Oriented Computing (SOC) is becoming the dominating paradigm for software development in many areas, including e-business, robotics, gaming, and scientific computation. One of the key issues lagging behind is the education. In spite of significant progress in SOC applications, SOC education has not been taught in introductory classes. Existing SOC courses are graduate or senior-level courses in universities that require full programming background. While various issues regarding SOC are being explored and discussed, the issues for SOC education, especially at high school level, still remain uncultivated, which does not match up with the importance of SOC paradigm. Sponsored by U.S. Department of Education, the Computer Science & Engineering Department and the College of Education at Arizona State University, in cooperation with Scottsdale Unified School District and Coronado High School, we pioneered the first SOC course for high school students in Spring 2007. The same course was taught to high school teachers in summer 2007, and the service-oriented robotics development part was taught to high school students in a summer camp in 2007. This paper discusses the design of the course and reports the experience and lessons in teaching these classes.","Title: Ontology-Based Test Modeling and Partition Testing of Web Services\nYear: 2008\n\nAbstract: Testing is useful to establish trust between service providers and clients. To test the service-oriented applications, automated and specification-based test generation and test collaboration are necessary. The paper proposes an ontology-based approach for Web Services (WS) testing. A Test Ontology Model (TOM) is defined to specify the test concepts, relationships, and semantics from two aspects: test design (such as test data, test behavior, and test cases) and test execution (such as test plan, schedule and configuration). The TOM specification using OWL (Web Ontology Language) can serve as test contracts among test components. Based on the WS semantic specification in OWL-S, the paper discusses the techniques to generate the sub-domains for input partition testing. Data pools are established for each parameter of the specified service. Data partitions are derived by class property and relationship analysis. Completeness and consistency (C&C) checking can be performed on the data partitions and data values, both within the TOM and against the OWL-S, by ontology class computation and reasoning. A prototype tool is implemented to support OWL-S analysis, test ontology generation and C&C checking.","Title: Optimized QoS-aware replica placement heuristics and applications in astronomy data grid\nYear: 2011\n\nAbstract: This paper studies the Quality-of-Service (QoS)-aware replica placement problem in a general graph model. Since the problem was proved NP-hard, heuristic algorithms are the current solutions to the problem. However, these algorithms cannot always find the effective replica placement strategy. We propose two algorithms that can obtain better results within the given time period. The first algorithm is called Cover Distance algorithm, which is based on the Greedy Cover algorithm. The second algorithm is an optimized genetic algorithm, in which we use random heuristic algorithms to generate initial population to avoid enormous useless searching. Then, the 0-Greedy-Delete algorithm is used to optimize the genetic algorithm solutions. According to the performance evaluation, our Cover Distance algorithm can obtain relatively better solution in time critical scenarios. Whereas, the optimized genetic algorithm is better when the replica cost is of higher priority than algorithm execution time. The QoS-aware data replication heuristic algorithms are applied into the data distribution service of an astronomy data grid pipeline prototype, and the operation process is studied in detail.","Title: Simulation Verification and Validation by Dynamic Policy Specification and Enforcement\nYear: 2006\n\nAbstract: This article presents a new verification and validation technique for simulation using dynamic policy specification and enforcement. Security requirements, certain functional requirements, and constraints can be formally specified as policies, and they are used to check at runtime whether the behaviors of the system under simulation are within the given constraints. A policy violation reveals a potential design error of the system under simulation. This article also presents the policy specification language and the policy development framework that are used to specify policies, to verify their completeness and consistency of policies, to translate them into executable representations, and to enforce them at runtime. The policy specification language and the policy development framework are fully integrated into the simulation infrastructure. An example is used throughout the article to illustrate the policy specification and enforcement processes. The article discusses different algorithms of policy enforcement and their space and time complexity.","Title: QoS Enhancement for PDES Grid Based on Time Series Prediction\nYear: 2007\n\nAbstract: The combination of parallel/distributed discrete event simulation (PDES) and Grid technology is a new trend in simulation. QoS is important yet difficult in this process. With the special features of Gird architecture and PDES input, such as periodical and predictable inputs, we could enhance QoS with a PDES-specific prediction. A Grid-based framework is presented that is designed to help predict the performance of PDES. Based on this framework, a prediction algorithm using time series theory is presented in the context of large scale Grid simulations. Experiments are executed in the context of GridSim, which shows methods discussed before to help to improve QoS level.","Title: A service scheduler in a trustworthy system\nYear: 2004\n\nAbstract: The aim of the research is to investigate techniques that support efficient service scheduling algorithms in a service-oriented fault-tolerant real-time distributed system. Techniques we developed include deadline-based real-time scheduling, priority-based scheduling, and redundant resource allocation for fault-tolerance. The system model and scheduling algorithms are designed, and a prototype is implemented to facilitate the investigation and experimentation.","Title: A software reliability model for web services\nYear: 2004\n\nAbstract: This paper proposes a service-oriented software reliability model that dynamically evaluates the reliability of Web services. There are two kinds of Web services: atomic services without the structural information and the composite services consisting of atomic services. The model first evaluates the reliability of atomic services based on group testing and majority voting. Group testing is the key technique proposed in this paper to support the service-oriented reliability model. Then, the reliability model evaluates the overall reliability of composite services using an architecture-based model and based on reliabilities of the atomic services, execution scenarios, and operational profiles. The reliability model is dynamic and the reliabilities of the services are evaluated in the actual operational environment. A case study is designed, implemented, and analyzed using the design of experiment technique. The results show the significances of the model and its components.","Title: Dependability modelling of homogeneous and heterogeneous distributed systems\nYear: 2001\n\nAbstract: In the past few years we have developed an experimental distributed system that supports multi-task applications with different levels of criticality. Software implemented fault-tolerant protocols are used to support dependable computing. This paper first presents Markov models of a distributed system under the occurrence of faults, reconfiguration and repair. As a part of our overall project, these models are intended for solving our particular problems, like assessing the merits of redundant schemes, task allocation and reallocation policies, and fault handling used in our experimental system. However, these models are developed in a generic way. They can also be used in evaluating individual task's reliability, risk and availability under various redundant schemes in any homogeneous distributed system. Then, we extend our study in analysing the dependability of the heterogeneous system consisting of a number homogeneous distributed systems connected through gateways","Title: Fast Detection of Path Failures in an Autonomous Decentralized System\nYear: 2011\n\nAbstract: An autonomous decentralized system and a series of methods for reducing the detection time of path failures in the system are developed. Computing devices in the proposed system are organized into at least three groups based on their connectivity of system’s graph model. Each computing device is assigned three identification values associated with their group memberships. The identification values are stored in a router connected to the communications network. Heartbeat packets are sent from the computing devices to the router periodically. If the router fails to receive a heartbeat packet from a computing device, a failed communication path from the router to the computing device is determined based on the three identification values.","Title: Design and Performance Evaluation of a Service-Oriented Robotics Application\nYear: 2009\n\nAbstract: Service-oriented computing (SOC) is becoming increasingly important and is being adopted by more and more organizations. However, the applications and research of SOC have been limited to Web services and enterprise systems. Embedded systems and robotics applications are recent domains that SOC has been applied to. This paper provides an insight about the application of SOC for robotics, event-driven paradigm of designing robotics system, and a model for publishing and utilizing the artifacts that are required for building SOC-based robotics applications. The main benefit of SOC robotics application is to have a layer of common services with standard interfaces. The invocations of the services are device-independent. In this way, we can deploy the same application to different robotics platforms, as long as we rebind the service invocation to the services that are built for the robotics platform. Sponsored by Intel, we have developed a number of prototypes using different boards, processors, and drive systems. We have measured the performance and power consumption of these prototypes.","Title: Service Replication Strategies with MapReduce in Clouds\nYear: 2011\n\nAbstract: The current implementations of cloud environment do not have suitable mechanism through which services can be managed to make use of cloud resources. The services in these environments can passively serve users' request only. If a service receives more requests than it can handle in a certain time period, it is subject to malfunctioning. This paper proposes a new approach to service replications that allows a cloud to adjust its service instance deployments in response to existing and projected service request loads. This approach defines an optimal service replication strategy based on MapReduce, a processing model used extensively in GAE (Google App Engine) to solve huge data processing tasks. This service replication strategy is implemented by Service Level MapReduce (SLMR). To better support for SLMR, service replication technology is introduced, which include dynamic service replication and pre-deployed service replication. Furthermore, a passive SLMR approach that depends on the cloud management service (CMS) and a positive SLMR approach that does not need the support from CMS will be introduced.","Title: Development of a Decentralized Virtual Service Redirector for Internet Applications\nYear: 1999\n\nAbstract: An ongoing project of the Highly Dependable Systems Research Program (PHDS) at the University of the Witwatersrand is the development of a dependable distributed system and its application in supporting Internet services. The current research related to this project includes the design, specification, verification and implementation of a virtual service redirector for critical internet applications. This paper summarizes this system and related projects.","Title: Ontology-Based Dependency-Guided Service Composition For User-Centric Soa\nYear: 2010\n\nAbstract: Service-Oriented Architecture (SOA) is characterized by dynamic service discovery and composition. For user-centric SOA, not only services, but workflows and application templates also can be published and discovered for composition. This paper proposes a two-steps composition process, ontology-based dependency-guided service composition (OBDG). In the first step, users compose their templates based on domain ontology or using existing templates. In the second step, users submit the templates to the OBDG system and let the system complete the dependencies by choosing and finalizing the selection of services and workflows from a set of candidate services or workflows based on user preferences. In this paper, services are described as interface service and implementation service. Interface service is like a service specification that describes service interface and its description, which is used to build domain ontology. Implementation services implement interface services. OBDG maintains a one-to-many relationship between them plus test scripts and cases. Templates are composed by interface services or test script so they can be instantiated by implementation services or test scripts and cases. In this way, application templates and testing templates can be same, which means OBDG can instantiate same template as application or testing by choosing implementation service or test script.","Title: Automatic Mutation Testing and Simulation on OWL-S Specified Web Services\nYear: 2008\n\nAbstract: Web Ontology Language for Services (OWL-S) is a standard XML-based language for specifying workflows and integration semantics among Web services (WS), which form composite WS. This paper analyzes the fault patterns of OWL-S specified composite WS and their workflows, proposes an ontology-based mutation analysis method, and applies specification-based mutation techniques for composite WS simulation and testing. Four categories of OWL-S mutant operators are specified, including data mutation, condition mutation, control flow mutation, and data flow mutation. Finally, the paper studies the ontology-based input mutation technique using a BookFinder service as a case study, which shows that ontology-based mutation provides viable test adequacy criteria for testing OWL-S specified composite WS.","Title: SOA Collaboration Modeling, Analysis, and Simulation in PSML-C\nYear: 2006\n\nAbstract: This paper extends the ebXML Web services development framework to introduce a new collaboration framework, which is based on the collaboration specification language PSML-C (Process Specification and Modeling Language for Collaboration), CCSOA (Consumer-Centric Service-Oriented Architecture), and DDSOS (Dynamic Distributed Service-Oriented Simulation) framework. Since collaborations are inevitable and play a critical role in SOA, an effective framework will greatly reduce the effort for rapid and adaptive service composition, simulation, evaluation, and collaboration. The PSML-C collaboration framework provides a service-oriented infrastructure for process collaboration specification, modeling, design, code generation, simulation, deployment, execution, and management. This paper presents the concepts, architecture, enabling techniques, and illustrative examples that demonstrate the concepts and the techniques","Title: Perspectives on Service-Oriented Computing and Service-Oriented System Engineering\nYear: 2006\n\nAbstract: The Service-Oriented Computing (SOC) paradigm leads the innovation of today's computing system and software development, and it can transform the human society into a new republic of all-to-all connected world. There are a number of interesting and innovative research challenges involved in achieving this vision of Service-Oriented System Engineering (SOSE). This paper highlights some of these significant research opportunities and also the need for enhanced education in this emerging area.","Title: Modeling and Simulation of Virtualized Autonomic Service Centers\nYear: 2008\n\nAbstract: Large service centers are becoming widely used to host many different services on a shared computing infrastructure, for which autonomic control and management are necessary to meet the service quality targets and maximize the overall profit. This paper presents the architecture, design and implementation of a framework for modeling and simulating virtualized autonomic service centers. This provides methods of estimating the system behavior for capacity planning before real establishment or execution. In addition, the performance of an existing service center can be efficiently evaluated. Performance analysis shows that our system is moderately efficient to perform large-scale simulation. Moreover, detailed evaluation results also depict various aspects of the feasibility and the efficiency of our modeling and simulation approaches, which can help to improve the productivity of researchers via quick proof of concepts.","Title: SOAVM: A Service-Oriented Virtualization Management System with Automated Configuration\nYear: 2008\n\nAbstract: Virtualization technologies are becoming more and more widely used in the distributed computing area. In order to organize and manage various virtual machines in the SOA (Service Oriented Architecture) environment more effectively, a virtualization management system called SOAVM is proposed and demonstrated in this paper. SOAVM addresses the limitation of virtual appliances in software quantities by employing ACS (Automated Configuration Service). ACS provides a more flexible way to conduct automated software configuration on virtual machines compared to the traditional virtual appliance pattern. The system framework is designed, which defines all functions of SOAVM as services to comply with SOA. Then the system design is described, illustrating how ACS works. Furthermore, critical implementation issues are discussed in detail, which demonstrates that SOAVM is a feasible and efficient virtualization management system.","Title: Dynamic system reconfiguration via service composition for dependable computing\nYear: 2005\n\nAbstract: Dependable service-oriented computing is challenging because it faces an open, heterogeneous, and dynamic computing environment. In a service-oriented computing system, services developed by different vendors ondifferent platforms and in different programming languages perform computations collaboratively through open standard protocols. This paper presents an innovative dynamic reconfiguration technology that can be embedded into a service-oriented application tomake the application reconfigurable. Traditional reconfiguration algorithmassumes each component can independently switch without collaboration. The proposed reconfiguration agents are embedded in different services, and they communicate via a collaborative reconfiguration protocol to achieve a consistent reconfiguration decision. In addition, the reconfiguration protocol itself is fault-tolerant.","Title: Internet of intelligent things and robot as a service.\nYear: 2013\n\nAbstract: The development of computing and communication systems has gone through a spiral cycle of centralization and decentralization paradigms. The earliest computer systems are centralized mainframe computers. The paradigm moved to decentralized as networked stations became more dependable, extensible and cost-effective. The decentralized systems have their limitations and inconveniences. The virtualization and cloud computing paradigm creates a centralized system that appears to users to be a centralized system, where computing and communication resources are not in the client computers but in an integrated infrastructure that is accessible anywhere and anytime. Nevertheless, the implementation of the centralized infrastructure is equipped with decentralized and redundant resources, which makes the system more dependable as any component failures can be tolerated internally. The Internet of Things extends the cloud computing concept beyond computing and communication to include everything, particularly, the physical devices. This paper discusses the architectures, interfaces, and behaviors of intelligent devices connected to the cloud computing environment. Robot as a Service is the case study, which has all the key features of Internet of Intelligent Things: autonomous, mobile, sensing, and action taking. The goal is to further extend the centralized cloud computing environment into a decentralized system to complete another cycle of the spiral development. The idea of achieving the goal is through autonomous and intelligent mobile physical services or robots as services to form local pool of intelligent devices and that can make local decisions without communicate with the cloud.","Title: Data provenance in SOA: security, reliability, and integrity.\nYear: 2007\n\nAbstract: Due to the dynamic nature, such as services composition and evaluation, it is critical for a Service- Oriented Architecture (SOA) system to consider its data prov- enance, which concerns security, reliability, and integrity of data as they are being routed in the system. In a traditional software system, one focuses on the software itself to deter- mine the security, reliability, and integrity of the software. In an SOA system, however, one also needs to consider ori- gins and routes of data and their impact, i.e., data provenance. This paper first analyzes the unique nature and characteristics of data provenance in an SOA system, particularly related to data security, reliability, and integrity. Then it proposes a new framework for data provenance analysis in an SOA system. Finally, this paper uses an example which illustrates these techniques.","Title: Service-oriented system engineering (SOSE) and its applications to embedded system development\nYear: 2007\n\nAbstract: In the past few years, we witnessed a rapid progress in service-oriented computing (SOC), which represents a new computing\n paradigm. SOC changes the way we develop and use software and hardware. Major enabling techniques, including service-oriented\n architecture (SOA), service-oriented enterprise (SOE), service-oriented infrastructure (SOI), Web services (WS), and associated\n protocols and standards are being established. This paper focuses on the system engineering issues and how these engineering\n issues manifested in SOA development processes. SOSE differs from traditional system engineering because it emphasizes on\n reusability, dynamic and adaptive nature, and unique model-driven approach.","Title: Choosing cost-effective configuration in cloud storage.\nYear: 2013\n\nAbstract: Cloud storage provides a virtually unlimited storage spaces for customers. Customers can combine their data storages from different types of cloud storage following their own requirements. End customers often stuck in choosing desirable configuration from different types of cloud storage. How to spend the minimum costs on using the highly efficient cloud storage? How to balance the relationship between the expenditures and performance? This paper proposes a cost-effective optimal configuration model using the repeated game model that can provide optimal configuration solutions to customers. The data mining techniques are used in provisioning on cloud storage. Classification helps users to find the related data and trend analysis assists users to mine the future trend on data storage. A simulate experiment is discussed and verify the correctness of the proposed model.","Title: Collaboration Policy Generation in Dynamic Collaborative SOA\nYear: 2007\n\nAbstract: Governance by policies is an important feature in Service-Oriented Architecture (SOA). This paper introduces a collaboration policy generation technique to govern dynamic collaboration in SOA systems. Dynamic collaboration allows two parties not knowing each other establish their collaboration protocol at runtime. Traditional SOA allows parties to collaborate but with a known collaboration protocol before execution. In dynamic collaboration, as collaboration protocols will be negotiated and determined at runtime, policies need to be generated at runtime to manage the interaction. This paper presents the concepts, architecture, and illustrative examples that demonstrate the dynamic collaboration policy generation technique.","Title: Binary analysis and automated hot patching for Web-based applications\nYear: 2006\n\nAbstract: Patching technologies are commonly applied to improve the dependability of software after release. This paper reports the design of an automated hot patching (AHP) framework that fully automates reasoning for the causes of failures and patching the binary code of Web-based applications. AHP admits the hardness for rooting out all faults before product release, and autonomously patches problems of application programs. By directly operating on binary code, AHP is universal to virtually all applications. A promising application of AHP is to shortcut a function of the remote maintenance center (RMC) and hence to reduce the turn around time for patches.","Title: Simulating highly dependable applications in a distributed computing environment\nYear: 2003\n\nAbstract: The aims of the research are to investigate techniques that support the development of highly dependable applications in a distributed system environment. Techniques we developed include redundant task allocation, load balancing, fault-tolerant computing and communication. The application we have implemented in the system is a firewall application. The firewall runs in redundant mode. Each incoming or outgoing packet is checked by two or more copies of the firewall application. Only when the majority of the firewall copies decide to accept the packet, the packet can go through the firewall. Different decisions from the different firewall copies signify a possible hardware fault or a software error in the underlying system. This paper reports a recent implementation of a simulation system, in which computing nodes, redundant copies of tasks and packet queues are implemented as independent threads, as well as experimental result we obtained based on queuing models.","Title: On Robotics Applications in Service-Oriented Architecture\nYear: 2008\n\nAbstract: Service-Oriented Computing (SOC) research and applications have been largely limited to software development in electronic and Web based applications. Service-oriented robotics software development extends SOC from its current fields to a new domain, which was considered not feasible because of the efficiency issues in terms of computing and communication. This paper presents the concepts, principles, and methods in SOC and SOC-based robotics software development and applies them in the design of distributed robotics applications. Two case studies, Intel security robot design and a maze-traversing robot application in Microsoft Robotics Studio, are used to illustrate the concepts and methods.","Title: The Triangular Pyramid Scheduling Model and algorithm for PDES in Grid\nYear: 2009\n\nAbstract: Grid is a perfect environment for the large scale Parallel Discrete Event Simulation (PDES), because its distribution and collaboration features match the PDES applications well. The PDES tasks or applications are modeled as a Directed Acyclic Graph (DAG), in which the simulation resources consist of three critical factors, simulation hosting machine (SHM), simulation service (SS) and simulation data (SD) in Grid environment. By solving the model we attempt to obtain an optimized triangular matching of the simulation resources on Grid, so that it can support the PDES activities better. We name the algorithm of solving the model Triangular Pyramid Scheduling (TPS). The PDES DAG is divided into three basic graph structures: Sequential structure, Fork structure, and Join structure. The TPS algorithm is developed based on these graph structures. The simulation results show that TPS algorithm can reduce the makespan and congestion, improve the simulation efficiency, and increase the resource utilization efficiency, compared to the existing algorithms.","Title: V3COCA: An effective clustering algorithm for complicated objects and its application in breast cancer research and diagnosis\nYear: 2009\n\nAbstract: In breast cancer studies, researchers often use clustering algorithms to investigate similarity/dissimilarity among different cancer cases. The clustering algorithm design becomes a key factor to provide intrinsic disease information. However, the traditional algorithms do not meet the latest multiple requirements simultaneously for breast cancer objects. The Variable parameters, Variable densities, Variable weights, and Complicated Objects Clustering Algorithm (V3COCA) presented in this paper can handle these problems very well. The V3COCA (1) enables alternative inputs of none or a series of objects for disease research and computer aided diagnosis; (2) proposes an automatic parameter calculation strategy to create clusters with different densities; (3) enables noises recognition, and generates arbitrary shaped clusters; and (4) defines a flexibly weighted distance for measuring the dissimilarity between two complicated medical objects, which emphasizes certain medically concerned issues in the objects. The experimental results with 10,000 patient cases from SEER database show that V3COCA can not only meet the various requirements of complicated objects clustering, but also be as efficient as the traditional clustering algorithms.","Title: Service-Oriented User Interface Modeling and Composition\nYear: 2008\n\nAbstract: Traditional service-oriented applications mainly focus on machine-to-machine interaction. However, human-machine interaction in applications also plays an important role. A better user interface can provide better usability and make the system user friendly. A user can be considered a service provider, where the user interaction is a workflow as a part of the system workflow and a user can place SOA User Interface (SOAUI) design into an overall system design. Traditionally, user interface design follows the MVC (Mode-View-Controller) architectural pattern. The SOAUI is a complement to the existing solution by providing the view for the application to the end-user.","Title: An adaptive model-free resource and power management approach for multi-tier cloud environments\nYear: 2012\n\nAbstract: With the development of cloud environments serving as a unified infrastructure, the resource management and energy consumption issues become more important in the operations of such systems. In this paper, we investigate adaptive model-free approaches for resource allocation and energy management under time-varying workloads and heterogeneous multi-tier applications. Specifically, we make use of measurable metrics, including throughput, rejection amount, queuing state, and so on, to design resource adjustment schemes and to make control decisions adaptively. The ultimate objective is to guarantee the summarized revenue of the resource provider while saving energy and operational costs. To validate the effectiveness, performance evaluation experiments are performed in a simulated environment, with realistic workloads considered. Results show that with the combination of long-term adaptation and short-term adaptation, the fluctuation of unpredictable workloads can be captured, and thus the total revenue can be preserved while balancing the power consumption as needed. Furthermore, the proposed approach can achieve better effect and efficiency than the model-based approaches in dealing with real-world workloads.","Title: A Hierarchical Reliability Model of Service-Based Software System\nYear: 2009\n\nAbstract: Service-Oriented Architecture (SOA) introduces a new paradigm where data, service, and the service composition logic are decoupled in an open environment. Software systems are built and evolved online by dynamic discovering and binding to the open services accessible through standard protocols. It requires new reliability modeling techniques to facilitate the analysis of dynamic collaborations and to be adaptable to the changes of service composition and system configuration at runtime. The paper proposes a hierarchical reliability model, in which the system reliability is calculated according to the layered superimposition of the reliabilities of data, services, fault-tolerant mechanism and service composition logic. At the basic-service layer, the service reliability is considered in the context of data reliability and service pools with backup alternatives. At the composition layer, a DTMC (Discrete Time Markov Chain) model is created for analyzing system reliability based on the reliability of the constituent services and their execution rate which are decided by the composite control structure and the operation scenarios. The DTMC state transition diagram can be automatically generated by analyzing and transforming the layered superimposition of the application following the transformation rules. The hierarchical modeling framework enables change adaptation at various levels. In addition, the models can be continuously learned and dynamically adjusted by profiling on the runtime monitoring log files.","Title: A Coverage Relationship Model for Test Case Selection and Ranking for Multi-version Software\nYear: 2007\n\nAbstract: Testing a group of software artifacts that implement the same specification can be time consuming, especially when the test case repository is large. In the meantime, some test cases may cover the same aspects in the software, thus it is not necessary to apply all the test cases. This paper proposes a Model-based Adaptive Test (MAT) case selection and ranking technique to eliminate duplicate test cases, i.e., test cases with the similar coverage, and rank the test cases according to their potency and coverage. This technique can be applied in various domains where multiple versions of applications are available to test, such as web service testing, n-version applications, regression testing, and standard-based testing. The MAT is based a statistical model based on earlier testing results, and the model can determine the next sets of test cases to minimize the testing effort. The MAT is then applied to testing of multi-versioned web services and the results shows that the MAT can reduce testing effort while still maintain the effectiveness of testing.","Title: Structure-oriented dependability evaluation of fault-tolerant protocols\nYear: 1994\n\nAbstract: Fault-tolerant protocols are special software components used to maintain correct communication and computing in highly dependable distributed systems. Before being put into use, the correctness or dependability of a fault-tolerant protocol must be ensured. Based on a deterministic test strategy with imperfect error correction, we propose and investigate a quantified reliability model for fault-tolerant protocols. The parameters of the model can be estimated from the frequencies of the failures attributable to a single design error and from the times between the failures attributable to different design errors observed during testing.","Title: Virtualization-based autonomic resource management for multi-tier Web applications in shared data center\nYear: 2008\n\nAbstract: As large data centers emerge, which host multiple Web applications, it is critical to isolate different application environments for security reasons and to provision shared resources effectively and efficiently to meet different service quality targets at minimum operational cost. To address this problem, we developed a novel architecture of resource management framework for multi-tier applications based on virtualization mechanisms. Key techniques presented in this paper include (1) establishment of the analytic performance model which employs probabilistic analysis and overload management to deal with non-equilibrium states; (2) a general formulation of the resource management problem which can be solved by incorporating both deterministic and stochastic optimizing algorithms; (3) deployment of virtual servers to partition resource at a much finer level; and (4) investigation of the impact of the failure rate to examine the effect of application isolation. Simulation experiments comparing three resource allocation schemes demonstrate the advantage of our dynamic approach in providing differentiated service qualities, preserving QoS levels in failure scenarios and also improving the overall performance while reducing the resource usage cost.","Title: Composing Highly Reliable Service-Oriented Applications Adaptively\nYear: 2008\n\nAbstract: This paper proposes dynamic and adaptive reliability methods that can be integrated into a collaborative composition framework with dynamic verification and adaptive reliability modeling. The composition process follows a template-based approach with ontology systems where a variety of items can be reused including services, workflows, application templates, and test cases/scripts. Items submitted to publication are subjected to test and evaluation before they can be published and reused. Test cases can also be ranked based on their effectiveness and test cases will be continuously re-ranked based on recent testing results and reliability modeling. Composed applications will be tested and evaluated before deployment, and even during execution, applications will be monitored so that their reliability can be continuously updated. This paper proposed several adaptive mechanisms to estimate software reliability and update test case effectiveness. They are illustrated by examples.","Title: Robot as a Service in Cloud Computing\nYear: 2010\n\nAbstract: Service-oriented architecture and cloud computing are becoming a dominant computing paradigm, as all major computing companies are supporting this paradigm and more and more organizations are adopting this paradigm. Robotics and service-oriented robotics computing start to joint this new paradigm in the past five years and are now ready to participate in large scale. This paper reports our research on service-oriented robotics computing and our design, implementation, and evaluation of Robot as a Service (RaaS) unit. To fully qualify the RaaS as a cloud computing unit, we have kept our design to comply with the common service standards, development platforms, and execution infrastructure. We also keep the source code open and allow the community to configure the RaaS following the Web 2.0 principles of participation. Developers can add, remove, and modify the RaaS of their own. For this purpose, we have implemented our RaaS on Windows and Linux operating systems running on Atom and Core 2 Duo architectures. RaaS supports programming languages commonly used for service-oriented computing such as Java and C#. Special efforts have been made to support Microsoft Visual Programming Language (VPL) for graphic composition. We are working with high schools to use RaaS and VPL in robotics camps and robotics competitions.","Title: Design of a Robot Cloud Center\nYear: 2011\n\nAbstract: Service-oriented architecture and cloud computing have become the prevalent computing paradigm. In this paradigm, computing resources can be accessed like other utility services available in today's society. In the meantime, robotics applications are joining the trend. More and more robot applications are shifting from manufacture to non-manufacture and service industries. However, for the on-demand supply of the large-scale heterogeneous robots, It is still a problem have not yet been studied, including the fundamental management and efficiency issues in using of these resources. In this paper, we design a framework of \"Robot Cloud Center\" (RCC) following the general cloud computing paradigm to address the current limitations in capacity and versatility of robotic applications. In this framework, a robot can be provided as a service just like a public utility service so that everyone can access the powerful robotic services easily, efficiently, and cheaply. Based on a given scenario, a robot scheduling algorithm in RCC is proposed to take advantage of the heterogeneous robot resources to meet the end user's requirement with the minimum cost.","Title: A content and user-oblivious video-recommendation algorithm\nYear: 2011\n\nAbstract: Videos have become popular on Internet, and corresponding video-recommendation algorithms have become an important factor for maintaining user’s satisfactory level and the profits of video-service providers. Existing recommendation algorithms are often highly dependent on the precious information of contents and users. However in many scenarios those information is not available for privacy reasons. This paper provides a watching sequence-based video-recommendation algorithm that can work well without the video contents and users information. The algorithm consists of three models: the exactly prefix matching tree, partial prefix matching tree, and the postfix matching tree. The final recommendation results are composed from the three models. The corresponding search tree, the matching search tree, and weight calculating algorithm are developed for each model. The algorithm is evaluated based on the half-year log files of a practical video website. The experimental results show that our algorithm performs better on execution time, accuracy, diversity of recommendation results, and non-hot coverage than the traditional recommendation algorithms.","Title: Autonomous hot patching for Web-based applications\nYear: 2005\n\nAbstract: Patching technologies are commonly applied to improve the dependability of software after release. This paper proposes an autonomous hot patching (AHP) framework to fully automate the reasoning for the causes of failures, and to patch the binary code of Web-based applications. AHP admits the hardness for rooting out all faults before product release, and autonomously patches problems of application programs. By directly operating on binary code, AHP is universal to virtually all applications. A promising application of AHP is to shortcut the remote maintenance center (RMC) and hence to reduce the turn around time for patches.","Title: An Introductory Course On Service-Oriented Computing For High Schools\nYear: 2008\n\nAbstract: Service-Oriented Computing (SOC) is a new computing paradigm that has been adopted by major computer companies as well as government agencies such as the Department of Defense for mission-critical applications. SOC is being used for developing Web and electronic business applications, as well as robotics, gaming, and scientific applications. Yet, SOC education is lagging. In spite of significant progresses in SOC technology and applications, SOC education has not been taught in introductory classes, even if it is technologically feasible. Most of the existing SOC courses are either graduate seminars or senior-level courses at various universities. On the other hand, SOC is component-based and introduces a high-level of abstraction, which makes it possible to teach computing within an application domain, such as robotics. In other words, the SOC learning process focuses more on the application logic rather than the syntax of programming languages, potentially making computer education entertaining. The Computer Science & Engineering Department and the College of Education at Arizona State University, in cooperation with the Scottsdale Unified School District and Coronado High School, pioneered the first SOC course for high schools (grades 9 through 12) in the Spring and Fall of 2007. The course was also offered in summers 2006, 2007, and 2008 to high school students and teachers. This course is designed so that even high school students without any computing training can learn the latest software technologies in an entertaining manner. Specifically, this course uses a visual programming environment so students can design their software visually. Thus, they can learn control constructs but do not need to focus on the details of programming language syntax. Furthermore, once the software is designed, a visual 3-D simulator can give students instantaneous feedback. Finally, the software designed can be downloaded into LEGO robots for robotic competition. Most students who took the course rated the course \"very well\" or \"pretty well\" and some indicated that they are interested enough to contemplate pursuing computer science as their career.","Title: Autonomous decentralised systems in web computing environment\nYear: 2011\n\nAbstract: This introductory note outlines autonomous decentralised systems (ADS) technologies as applied to service-oriented computing (SOC) and cloud computing environments, and also introduces the papers in the special issue.","Title: Mutation-Based Simulation Test Data Generation for Testing Complex Real-Time Software\nYear: 2007\n\nAbstract: Simulation is proven to be an effective way for testing complex real-time hardware/software systems. However, simulation test data generation is a challenging issue which determines the efficiency in such testing. This paper proposed a data-driven mutation based approach for test data generation to address the unique requirements of real-time, input domain coverage, adaptability, and reliability. The architecture is designed to simulate the process for data sampling, transforming, packaging, and transmitting segments in an aerospace ground control system. Various mutant operators are defined for signal generation and data package generation to produce fault-sensitive inputs based on the system's fault pattern analysis. Mechanisms are defined to generate a large number of test cases by combination and composition of various data outputs from different dimensions to achieve a high coverage. A configuration mechanism is introduced to enable recomposition and re-combination of simulation components. The selective simulation testing method is discussed to improve test effectiveness. A case study shows that the proposed approach can achieve a high fault-coverage with a small number of effective test cases.","Title: Roadmap to a Full Service Broker in Service-Oriented Architecture\nYear: 2007\n\nAbstract: Service-broker is an important mechanism in Service-Oriented Architecture (SOA), which facilitates service registration, publication, and discovery. UDDI and ebXML are two major standards that implement service brokerage by providing service registry and service repository. As SOA applications become pervasive, the need for more powerful service broker becomes a necessity. This paper explores the features, criteria of the future service brokers that can meet the increasing needs in SOA software development.","Title: Service-orientation in computing curriculum\nYear: 2011\n\nAbstract: Web software development and cloud computing based on Service-Oriented Architecture (SOA) and Service-Oriented Computing (SOC) represent the modern software engineering theories, practices, and technologies. As an architecture-driven computing paradigm, SOA and SOC are mature and are becoming the major paradigm for software development. SOA and SOC should be taught in all computer science and computer engineering programs. We do not suggest using SOC to replace the currently taught Object-Oriented Computing (OOC) paradigm. As SOC is based on OOC, we suggest to teaching SOC as the continuation and extension of OOC. At Arizona State University, SOA and SOC paradigm is incorporated into our Computing Science and Software Engineering programs since 2006. This paper presents the topics of the related courses and the open resources created for the courses, which are available for public accesses, including textbooks, lecture presentation slides, tests and assignments, software tools, a repository of sample services and applications, and tutorials of using tools and the cloud computing environment for service hosting and deployment.","Title: An Infrastructure for Web Services Migration for Real-Time Applications\nYear: 2006\n\nAbstract: Service-oriented architecture (SOA) is a highly promising technology for software development. It can greatly reduce the development time and cost and achieve system agility. Web service is the current practice for realizing SOA. Due to the nature of widely distributed Web service providers, the service performance could be impacted when the network traffic is congested. There are methods, such as communication cost based service selection strategies, developed to cope with the problem. In this paper, we propose a complementing technology, migratable Web services, to overcome the performance problems for real-time applications. A service can be implemented by multiple light weighted Web services and some of them can be migrated to strategic sites to minimize the communication delays so the real-time requirements can be met. We have designed an infrastructure to support Web service migration and execution. Also, appropriate decision mechanism, which decides whether a Web service should be migrated and where to send it to, is the key for major performance gains. We use genetic algorithm to efficiently make the best migration decisions. Experimental studies show that the approach can achieve significant performance improvement","Title: Assuring Mobile Physical Services for the New Generation of Networks\nYear: 2011\n\nAbstract: The development of computing and communication systems has gone through a spiral cycle of centralization and decentralization schemas. The earliest telephone network used decentralized point-to-point connections. It moved to centralized switching system as the number of devices increased. The centralized computing and communication systems further moved into a decentralized paradigm, as devices expand and dependability of large systems becomes a dominating factor. The current cloud computing and communication systems appear to be a centralized system where computing and communication resources are not in the client computers but in an integrated infrastructure. Nevertheless, the implementation of the centralized infrastructure is equipped with decentralized and redundant resources, which makes the system more dependable as any internal failures can be tolerated internally. However, the terminal devices and their interfaces to the centralized infrastructure remain vulnerable to the single-point-of-failures. This paper focuses on terminal devices and their interfaces to the new generation of assurance network and presents the challenges of making the devices and the interfaces as dependable as the assurance network. The idea of achieving the goal is through a pool of Mobile Physical Services (MPS) that can connect to multiple networks and can be shared by neighboring users.","Title: UCSOA: User-Centric Service-Oriented Architecture\nYear: 2006\n\nAbstract: This paper introduces a new user-centric serviceoriented architecture (UCSOA) that allows end users to compose applications. UCSOA is an extension of consumer-centric service-oriented architecture CCSOA), which is an extension of conventional SOA. The conventional SOA is producer-centric because service providers publish their services and service consumers must search available services to compose their applications. CCSOA is different as it allows consumers publish their needs including workflows and services, and let producers to produce services to meet the requirements. Based on CCSOA, UCSOA provides support for end users. An application builder is an engineer who has both domain and programming knowledge, while an end user has little knowledge on programming and thus UCSOA needs to allow nontechnical persons to compose their applications. This paper presents the concepts, architecture, enabling techniques, and illustrative examples.","Title: A service-oriented modeling and simulation framework for rapid development of distributed applications\nYear: 2006\n\nAbstract: The paper presents a service-oriented distributed modeling and simulation framework that supports the development and evaluation of large scale distributed systems such as network-centric and system-of-systems applications. The distinct features of the framework include a modeling and specification language, dynamic model checking for completeness and consistency, automated code generation from the specification, simulation of different architectures with a template-based platform builder, service-oriented multi-agent simulation for easy re-configuration and re-composition, formal policy specification and enforcement for dynamic verification, and dynamic analyses for evaluation and monitoring. The framework and most of the tools reported in this paper have been implemented and applied in several industrial projects. This paper presents the design principles, user interfaces, its runtime infrastructure, and the experiment results on its performance.","Title: A Machine Learning-Based Reliability Assessment Model for Critical Software Systems\nYear: 2007\n\nAbstract: Service-oriented architecture (SOA) techniques are being increasingly used for developing critical applications, especially network-centric systems. While the SOA paradigm provides flexibility and agility to better respond to changing business requirements, the task of assessing the reliability of SOA-based systems is challenging, especially for composite services. However, deriving high confidence reliability estimates for missioncritical systems can require huge costs and time. This paper presents a reliability assessment and prediction model for SOA-based systems. The services are assumed to be realized with reuse and logical composition of components. The model uses AI reasoning techniques on dynamically collected failure data of each service and its components as one of the evidences together with results from random testing. Memory-Based Reasoning technique and Bayesian Belief Networks are used as reasoning tools to guide the prediction analysis. The least tested and \"high usage\" input subdomains are identified and necessary remedial actions are taken depending on the predicted results from the proposed model. The model is illustrated using a simulated case study based on a real-time dataset from the NASA software repository.","Title: The Temporal Correlation Hypothesis For Self-Organizing Feature Maps\nYear: 2000\n\nAbstract: Feature maps, in which one or more aspects of the environment are systematically represented over the surface of the cerebral cortex, are of ten found in primary sensory and motor cortical regions of the vertebrate brain. They have inspired a great deal of computational modelling, and this has provided evidence that such maps are emergent properties of the interactions of numerous cortical neurons and their adaptive, nonlinear connections. In this paper, we address the issue of how multiple feature maps that coexist in the same region of cerebral cortex align with each other. We hypothesize that such alignment is governed by temporal correlations : features in one map that are temporally correlated with those in another come to occupy the same spatial locations over time. To examine the feasibility of this hypothesis and to establish some of its detailed implications, we initially studied a computational model of primary sensorimotor cortex. Coexisting sensory and motor maps formed and generally aligned in a fashion consistent with the temporal correlation hypothesis. We summarize these results, and then mathematically analyse a simplified model of self-organization during unsupervised learning. We show that the properties observed computationally are quite general : that temporally correlated inputs become spatially correlated (i.e. aligned), while input patterns that are temporally anti-correlated tend to result in mutually exclusive (i.e. unaligned) spatial distributions. This work provides a framework in which to interpret and understand future experimental studies of map relationships.","Title: A Cost-Effective Intelligent Configuration Model in Cloud Computing\nYear: 2012\n\nAbstract: Cloud computing environments provide a resource pool for customers for their processing, storage and networking needs. It is necessary for customers to choose desirable configuration from vast resources available in the cloud. This paper proposes a heuristic model to choose a cloud configuration for efficient use. Trend analysis in data mining is used to predict the future trend and assist provisioning. The model is experimented with Intel power 32 core machine and in Azure cloud. Both environments demonstrated that the proposed model provided effective solutions.","Title: Typical Virtual Appliances: An optimized mechanism for virtual appliances provisioning and management\nYear: 2011\n\nAbstract: A computing infrastructure requirement in the cloud computing environment can be specified and composed using virtual appliances, which forms the infrastructure-as-a-service (IaaS). Due to the diversity of user requirements, a large number of virtual appliances may be needed. We propose a mechanism called Typical Virtual Appliances (TVAs), an efficient method for providing virtual appliances. In this paper, we present the concept of TVAs and formulate it as an optimization problem with given constraints. With analysis of the software download logs of real web sites, we discover that the number of user requirements follows a quadratic polynomial distribution, and the user requirements are clustered in nature. According to this finding, we develop a clustering-based TVAs generation algorithm, and we show that this algorithm can achieve the optimal result. The clustering algorithm can generate TVAs, which can be transformed to other virtual appliances easily and efficiently. We further design a TVA Management System (TVAMS) to support this mechanism. The simulation results show that our method can meet most of the user requirements efficiently with low storage overhead.","Title: Virtual Workspace Based Job Execution Methods and Dynamic Makespan Optimized Scheduling Algorithms\nYear: 2008\n\nAbstract: The virtualization technology is helpful to support grid QoS. A manual configuration method and an automatic configuration method are designed to build the virtual workspace environment based on virtualization technology. Both the MetaServices and the automatic configuration software are employed to establish the virtual workspace environment. For dynamic jobs, the corresponding Dynamic Makespan Optimized (DMO) scheduling algorithms are developed. Results of the simulation experiments demonstrate that, compared to models without virtualization support, the job execution methods and DMO scheduling algorithms proposed in this paper can achieve higher throughput, optimize job makespan, and improve the QoS of grid systems.","Title: An Approach for Service Composition and Testing for Cloud Computing\nYear: 2011\n\nAbstract: As cloud services proliferate, it becomes difficult to facilitate service composition and testing in clouds. In traditional service-oriented computing, service composition and testing are carried out independently. This paper proposes a new approach to manage services on the cloud so that it can facilitate service composition and testing. The paper uses service implementation selection to facilitate service composition similar to Google’s Guice and Spring tools, and apply the group testing technique to identify the oracle, and use the established oracle to perform continuous testing for new services or compositions. The paper extends the existing concept of template based service composition and focus on testing the same workflow of service composition. In addition, all these testing processes can be executed in parallel, and the paper illustrates how to apply service-level MapReduce technique to accelerate the testing process.","Title: Dynamic Collaboration Simulation in Service-Oriented Computing Paradigm\nYear: 2007\n\nAbstract: In Service-Oriented Architecture (SOA) and Service-Oriented Computing (SOC), service collaboration is an important aspect. While service collaboration protocols for data exchange are well explored, the Dynamic Process Collaboration (DPC) is still a challenging issue. The DPC brings new features and uncertainty to the current SOA/SOC, such as run-time behavior evaluation, dynamic collaboration performance measurement and dynamic Recomposition/ Reconfiguration capability assessment. This paper presents the Dynamic Service-Oriented Collaboration Simulation (DSOCS) framework we have developed, which supports the dynamic collaboration, development, simulation, and evaluation of large scale SOA systems. The distinct features of the framework include automated simulation code generation from the specification, code deployment, and simulation of different architectures with a template-based platform builder, service-oriented multi-agent simulation for easy reconfiguration, and dynamic analyses of results from evaluation and monitoring. The framework and the associated tools have been implemented and applied in several governmental and industrial projects.","Title: Ontology-based Dynamic Process Collaboration in Service-Oriented Architecture\nYear: 2007\n\nAbstract: Service collaboration is important in Service- Oriented Architecture (SOA). While service collaboration protocols for data exchange are well explored, the Dynamic Process Collaboration (DPC) is still a challenge. DPC requires not only exchanging meaningful information between collaboration parties, but also performing collaboration workflow matching based on collaboration ontology. To do this, DPC needs service collaboration ontology modeling, service collaboration discovery and establishment based on collaboration ontology and runtime recomposition capability. This paper presents an Ontology-based Dynamic Process Collaboration (ODPC) framework with these features to facilitate DPC.","Title: A framework for contract-based collaborative verification and validation of web services\nYear: 2007\n\nAbstract: A key issue with Web Services (WS) is the verification and validation (V&V) of services to build trust between service providers and service users. This paper proposed a test-broker architecture so that all stakeholder within WS can contribute to improve the testing of the services. The test broker supports the submission, indexing, and querying of test artifacts such as test cases, defect reports and evaluations. It can also provide the services for the test generation, test coordination, and distributed testing services. The DCV&V (Decentralized, Collaborative, Verification and Validation) framework is proposed with a set of distributed and collaborated test brokers dedicated to different V&V tasks to enable scalable and flexible test collaborations. The paper explores the concept of design-by-contract and applies the principle to DCV&V. It identifies two categories of testing contracts including TSC (Testing Service Contracts) and TCC (Test Collaboration Contracts). It illustrates the application of TSC with contract-based test generation based on WS OWL-S specification. It elaborates TCC with the analysis of the test artifacts definitions.","Title: The Simulation of a Highly Dependable Distributed Computing Environment.\nYear: 2003\n\nAbstract: The aim of the research is to investigate techniques that support the development of highly dependable applications in a distributed system environment. Techniques developed include redundant task allocation, load balancing, fault-tolerant computing, and communication. The application the authors have implemented in the system is a firewall application. The firewall runs in redundant mode. Each incoming or outgoing packet is checked by two or more copies of the firewall application. Only when the majority of the firewall copies decide to accept the packet can the packet go through the firewall. Disagreed decision from the different firewall copies signify a possible hardware fault or a software error in the underlying system. This article reports a recent implementation of a simulation system in which computing nodes, redundant copies of tasks, and packet queues are implemented as independent threads, as well as experiment results obtained based on queuing models.","Title: Priori information and sliding window based prediction algorithm for energy-efficient storage systems in cloud.\nYear: 2013\n\nAbstract: One of the major challenges in cloud computing and data centers is the energy conservation and emission reduction. Accurate prediction algorithms are essential for building energy efficient storage systems in cloud computing. In this paper, we first propose a Three-State Disk Model (3SDM), which can describe the service quality and energy consumption states of a storage system accurately. Based on this model, we develop a method for achieving energy conservation without losing quality by skewing the workload among the disks to transmit the disk states of a storage system. The efficiency of this method is highly dependent on the accuracy of the information predicting the blocks to be accessed and the blocks not be accessed in the near future. We develop a priori information and sliding window based prediction (PISWP) algorithm by taking advantage of the priori information about human behavior and selecting suitable size of sliding window. The PISWP method targets at streaming media applications, but we also check its efficiency on other two applications, news in webpage and new tool released. Disksim, an established storage system simulator, is applied in our experiments to verify the effect of our method for various users’ traces. The results show that this prediction method can bring a high degree energy saving for storage systems in cloud computing environment.","Title: Services utility prediction on a cloud\nYear: 2011\n\nAbstract: Cloud computing and Software-as-a-Service (SaaS) are being widely applied. In the near future, there will be many cloud services providing similar services. One of the issues is to dispatch service requests to available services dynamically so that service requests can be served in the most effective and efficient way. This paper proposes an algorithm that efficiently serves requests for services by predicting the number of services needed. Furthermore, a cloud architectural framework to support the algorithm and prediction model is introduced. The paper also presents a simulation study to validate the algorithm proposed.","Title: Voting Multi-Dimensional Data with Deviations for Web Services under Group Testing\nYear: 2005\n\nAbstract: Web Services (WS) need to be trustworthy to be used in critical applications. A technique called WS Group Testing has been proposed which can significantly reduce the cost of testing and ranking a large number of WS. A main feature of WS group testing is that it is able to establish the test oracles for the given test inputs from multiple WS and infer the oracles by plural voting. Efficient voting of complex and large number of data is critical to the success of group testing. Current voting techniques are not designed to deal with such a situation. This paper presents efficient voting algorithms that determine the plural value on multi-dimensional data and large number of data. The algorithm uses a clustering method to classify data into regions to identify the plural value. Experiments are designed and performed to concept-prove the algorithms and their applications with group testing.","Title: DDSOS: A Dynamic Distributed Service-Oriented Simulation Framework1\nYear: 2006\n\nAbstract: This paper presents the DDSOS framework developed at Arizona State University, which supports the simulation, development, and evaluation of large scale distributed systems such as network-centric and system-of-systems applications. The distinct features of the framework include automated simulation code generation from the specification, code deployment, simulation of different architectures with a templatebased platform builder, service-oriented multi-agent simulation for easy reconfiguration, and dynamic analyses of results from evaluation and monitoring. The framework and the associated tools have been implemented and applied in several governmental and industrial projects.","Title: Swiss Cheese Test Case Generation for Web Services Testing\nYear: 2005\n\nAbstract: Current Web services testing techniques are unable to assure the desired level of trustworthiness, which presents a barrier to WS applications in mission and business critical environments. This paper presents a framework that assures the trustworthiness of Web services. New assurance techniques are developed within the framework, including specification verification via completeness and consistency checking, test case generation, and automated Web services testing. Traditional test case generation methods only generate positive test cases that verify the functionality of software. The proposed Swiss Cheese test case generation method is designed to generate both positive and negative test cases that also reveal the vulnerability of Web services. This integrated development process is implemented in a case study. The experimental evaluation demonstrates the effectiveness of this approach. It also reveals that the Swiss Cheese negative testing detects even more faults than positive testing and thus significantly reduces the vulnerability of Web services.","Title: Bounds on the reliability of distributed systems with unreliable nodes and links\nYear: 2004\n\nAbstract: The reliability of distributed systems & computer networks in which computing nodes and/or communication links may fail with certain probabilities have been modeled by a probabilistic network. Computing the residual connectedness reliability (RCR) of probabilistic networks under the fault model with both node & link faults is very useful, but is an NP-hard problem. Up to now, there has been little...","Title: Distributed collaborative filtering with singular ratings for large scale recommendation\nYear: 2014\n\nAbstract: Collaborative filtering (CF) is an effective technique addressing the information overloading problem, where each user is associated with a set of rating scores on a set of items. For a chosen target user, conventional CF algorithms measure similarity between this user and other users by utilizing pairs of rating scores on common rated items, but discarding scores rated by one of them only. We call these comparative scores as dual ratings, while the non-comparative scores as singular ratings. Our experiments show that only about 10% ratings are dual ones that can be used for similarity evaluation, while the other 90% are singular ones. In this paper, we propose SingCF approach, which attempts to incorporate multiple singular ratings, in addition to dual ratings, to implement collaborative filtering, aiming at improving the recommendation accuracy. We first estimate the unrated scores for singular ratings and transform them into dual ones. Then we perform a CF process to discover neighborhood users and make predictions for each target user. Furthermore, we provide a MapReduce-based distributed framework on Hadoop for significant improvement in efficiency. Experiments in comparison with the state-of-the-art methods demonstrate the performance gains of our approaches.","Title: Design and analysis on trusted network equipment access authentication protocol.\nYear: 2015\n\nAbstract: Cloud security is a system engineering problem. A common approach to address the problem is to adapt existing Trusted Network Connection (TNC) framework in the cloud environment, which can be used to assess and verify end clients’ system state. However, TNC cannot be applied to network equipment attached to the cloud computing environment directly. To allow the network devices to access the trusted network devices safely and reliably, we first developed a Trusted Network Equipment Access Authentication Protocol (TNEAAP). We use the BAN logic system to prove that TNEAAP is secure and credible. We then configure the protocol in an attack detection mode to experimentally show that the protocol can withstand attacks in the real network. Experiment results show that all the nine goals that decide the protocol’s security have been achieved.","Title: On monitoring and predicting mobile network traffic abnormality.\nYear: 2015\n\nAbstract: Traffic analysis and traffic abnormality detection are emerged as an efficient way of detecting network attacks in recent years. The existing approaches can be improved by introducing a new model and a new analysis method of network user’s traffic behaviors. The description dimensions to network user’s traffic behaviors in the current approaches are high, resulting in high processing complexity, high delay in differentiating an individual user’s abnormal traffic behavior from massive network data, and low detection rate. To improve the detection rate and efficiency, we develop a new method of establishing user’s traffic behavior analysis system based on a new model of network traffic monitoring. First, we establish a more complete feature set based on the characteristics of network traffic to describe massive network user’s behaviors. Then, we define a feature selection rule based on the relative deviation distance to select the optimized feature set. We use the selected feature set to locate the abnormality moment and the users who produce the abnormal traffic behavior. Finally, a traffic behavior analysis method based on prediction is developed to improve efficiency of the system. This new method is applied to evaluate the mobile users on mobile cloud. The experimental results show that the proposed method has a higher detection rate and lower delay in the analysis of abnormal user’s traffic behavior than that of the existing approaches.","Title: Service-Oriented Computing and Software Integration in Computing Curriculum\nYear: 2014\n\nAbstract: Web software development and cloud computing based on Service-Oriented Architecture (SOA) represent the latest parallel distributed computing theories, practices, and technologies. As a distributed software development diagram, SOA is being taught in many computer science programs. We do not suggest using SOA to replace the currently taught Object-Oriented Computing paradigm. As SOA is based on Object-Oriented Computing, we suggest teaching SOA as the continuation and extension. At Arizona State University, SOA paradigm is incorporated into our Computing Science program since 2006. This paper presents the topics of the related courses and the open resources created for the courses, which are available for public accesses, including textbooks, lecture presentation slides, tests and assignments, software tools, and a repository of components, services and applications.","Title: Trust-Based Security for the Spanning Tree Protocol\nYear: 2014\n\nAbstract: Attacks executed on Spanning Tree Protocol (STP) expose the weakness of link layer protocols and put the higher layers in jeopardy. Although the problems have been studied for many years and various solutions have been proposed, many security issues remain. To enhance the security and credibility of layer-2 network, we propose a trust-based spanning tree protocol aiming at achieving a higher credibility of LAN switch with a simple and lightweight authentication mechanism. If correctly implemented in each trusted switch, the authentication of trust-based STP can guarantee the credibility of topology information that is announced to other switch in the LAN. To verify the enforcement of the trusted protocol, we present a new credible evaluation method of the STP using a specification-based state model. We implement a prototype of trust-based STP to investigate its practicality. Experiment shows that the trusted protocol can achieve security goals and effectively avoid STP attacks with a lower computation overhead and good convergence performance.","Title: A Foot-Mounted Sensor Based 3D Indoor Positioning Approach\nYear: 2015\n\nAbstract: We present a 3D indoor positioning system with foot mounted low cost MEMS sensors. The sensors includes the accelerometers, gyroscopes, and barometer. The output of accelerometers and gyroscopes are used to calculate the zero velocity update (ZUPT) and the movement of one step. The barometer is used to detect the altitude changes. A Kalman filter based framework is used to fusion the outputs of the sensors and estimate the non-linear errors of the position and heading, which increased over time. A particle filter is used to further reduce the errors. The test result shows that the designed system perform well.","Title: Evaluation of deterministic fault injection for fault-tolerant protocol testing\nYear: 1991\n\nAbstract: A deterministic test strategy consisting of deterministic fault injection at the message level is investigated. Messages sent by faulty units are replaced by such wrong messages that cause all program parts of the faultless protocol units to be executed subsequently. Since this well-aimed fault injection poses complex problems, heuristics based on the program flow of previous injections of wrong messages is dynamically applied. The program parts to be tested are selected with increasing granularity until either a design error is found or sufficient structural coverage is reached, which reflects the portion of tested program parts. Using a simplified program model, an algebraic analysis of the structural coverage and the design error coverage, which is the probability to reveal an existing design error, is carried out. It is shown that fault-tolerant protocol testing by deterministic fault injection achieve better coverages than by random fault injection.<>","Title: Progressive ranking and composition of Web services using covering arrays\nYear: 2005\n\nAbstract: Major computer companies and government agencies are adopting Web services (WS) technology. Web services must ensure interoperability and security, and be reliable and trustworthy. Consumers must make runtime decisions based on an intelligent and unbiased evaluation. We propose one component of a test suite generator to address this critical issue. The goal is to transform the labor-intensive software development process into a largely automated Web services development process. The method operates within a service-oriented architecture, with the models and tools implemented as services that can be added, removed and replaced at runtime. We propose a generic greedy algorithm based on covering arrays for application in this environment.","Title: Specification-based verification and validation of Web services and service-oriented operating systems\nYear: 2005\n\nAbstract: Service-oriented architecture (SOA) and Web services (WS) have received significant attention recently. Even though WS are based on open standards and support software interoperability, but the trustworthy issues of WS has actually limited the growth of WS applications as organizations do not trust those WS developed by other vendors and at the same time they do not have access to the source code. This paper addressed this issue by proposing several solutions including specification-based verification and validation, collaborative testing, and group testing. The key concept is that it is possible to provide a comprehensive evaluation of WS even if their source code is not available.","Title: Stochastic voting algorithms for Web services group testing\nYear: 2005\n\nAbstract: This paper proposes a stochastic voting for testing a large number of Web services (WS) under group testing. In the future, a large number of WS would be available and they need to be tested and evaluated in real time. While numerous test input generation techniques are available to generate test inputs, the oracle or the expected output of these test input is often difficult to obtain. One way to obtain the oracle in this case is to give the same input to multiple WS and to establish the oracle by a majority voting. This is based on the assumption that faulty WS often would not produce consistent results, and thus if a majority can be reached, the oracle can be established statistically. However, even correct WS may still produce slightly different outputs, and thus the majority-voting scheme must be carefully designed to distinguish correct but slightly variant output from truly incorrect output. This paper proposes a hierarchical classification based on simulated annealing and multi-dimensional Chi-square statistical techniques to analyze data to see if a majority can be reached. The algorithm is evaluated by a comprehensive simulated data as well as actual data. The data show that the proposed algorithm is effective even in a difficult situation where clusters of WS produce clusters of output.","Title: Testability of Software in Service-Oriented Architecture\nYear: 2006\n\nAbstract: Service-Oriented Architecture (SOA) is a system architecture in which a collection of loosely coupled services communicate with each other using standard interfaces and message-exchanging protocols. As an emerging technology in software development, the SOA presents a new paradigm, and it affects the entire software development cycle including analysis, specification, design, implementation, verification, validation, maintenance and evoluation. This paper proposes several testability evaluation criteria for SOA software, which serves as a reference for both service providers and application builders to evaluate the test support to SOA software. The proposed evaluation criteria are illustrated in a stock-trading case study.","Title: Process Specification and Modeling Language for Service-Oriented Software Development\nYear: 2007\n\nAbstract: This paper focuses on the service-oriented system engineering issues using PSML (Process Specification and Modeling Language) framework. The key innovations of the framework are the PSML-based service-oriented software development and Single Model with Multiple Analyses (SMMA) model-driven architecture. SMMA uses one integrated core model, the PSML model, to derive other models for code generation simulation, and various analyses, which leads to the service-oriented system engineering.","Title: SOA Simulation and Verification by Event-Driven Policy Enforcement\nYear: 2008\n\nAbstract: The verification of SOA (Service-Oriented Architecture) applications is important, and, simulation is a promising method because it provides runtime behavior and performance analysis. This paper uses a BPEL engine as a simulation engine to simulate SOA applications, and proposes an event- driven policy enforcement framework to verify the SOA applications during simulation.","Title: On Testing and Evaluating Service-Oriented Software\nYear: 2008\n\nAbstract: As service-oriented architecture matures and more Web services become available, developers must test an ever-increasing volume of services. A framework that defines and evaluates test-case potency based on coverage relationships can reduce testing effort while maintaining testing's effectiveness.","Title: Biased covering arrays for progressive ranking and composition of Web Services\nYear: 2007\n\nAbstract: Service-oriented computing is a new software development paradigm that allows application builders to choose from many available services. The challenges are to efficiently determine which services are the most appropriate to combine into an application based on concerns such as functionalities, licensing costs, and known reliability. Group testing has addressed some issues on how to select a small subset of candidate services. We expand upon the group testing methodology with a greedy algorithm that generates biased covering arrays for interactive testing of the services selected by group testing.","Title: A green-aware virtual machine migration strategy for sustainable datacenter powered by renewable energy\nYear: 2015\n\nAbstract: •We propose a green-aware approach for managing VMs in datacenters.•Models are established for datacenters, VMs and power consumption.•An optimization problem is formulated to incorporate revenue and costs.•Three strategies designed to manage VMs dynamically are implemented.•The proposed approach is proved to be feasible in utilizing green energy.","Title: Developing a Security Robot in Service-Oriented Architecture\nYear: 2008\n\nAbstract: Service composition accelerates rapid application development, service reuse, and complex service consummation, thus, quantitative characteristics such as service execution throughput should be evaluated to measure the system performance. Based on Continuous ...","Title: Web Service Group Testing with Windowing Mechanisms\nYear: 2005\n\nAbstract: ASTRAR provides a framework for testing Web Services (WS) using the group testing technique. This paper extends the basic two-phase testing process and introduces the windowing mechanism to further improve testing efficiency. Rather than testing a large number of WS simultaneously, WS are divided into subsets called windows and testing is exercised window by window. Testing results are analyzed for different strategies such as using all of the historical data, using the most recent windows, and using the current window only. Based on the results, test cases are ranked according to their potency to detect faults; and oracles and the confidence level of each oracle are established for individual test cases at run-time. In addition, different strategies are proposed to determine the optimal window size at run-time. By incorporating the windowing mechanism, the two-phase training and volume testing process becomes a continuous learning process and the basic group testing process becomes more adaptive to dynamically changing environment.","Title: WSDL-Based Automatic Test Case Generation for Web Services Testing\nYear: 2005\n\nAbstract: In the past a few years, we witnessed a rapid progress in Service-Oriented Computing (SOC), which represents a paradigm shift from the current mainstream Object-Oriented Computing (OOC) paradigm to the SOC paradigm. This paradigm shift is changing the ...","Title: Automatically Building Service Evaluation Metadata in a Grid Environment\nYear: 2006\n\nAbstract: This paper presents a mechanism that automatically build evaluation metadata for grid services by using the information from the execution of different applications. A new MetaService AMDBS, Automatic Metadata Building Service, is designed to support this mechanism. The typical feature of this mechanism is that it can get not only the absolute evaluation information, but also the relative global ranking result through the collaboration of different AMDBSs. Web Service group testing is used as an example of a grid application to accelerate the process of evaluation metadata building. Simulation experiment results show that the HP (Heavy-Powerful) algorithm which is designed based on the dynamic evaluation metadata can improve the application performance significantly, compared with the RR (Round-Robin) algorithm which does not use the evaluation metadata. The effect of using evaluation metadata in different task and resource conditions is also demonstrated by experiment results.","Title: Consumer-Centric Service-Oriented Architecture: A New Approach\nYear: 2006\n\nAbstract: This paper extends the current Service-Oriented Architecture (SOA) to introduce a Consumer-Centric Service-Oriented Architecture (CCSOA) paradigm. The current SOA is producer-centric, because the basic idea is that service providers publish services that they produce and let the consumers to search available services to compose their applications. CCSOA focuses on consumers' publishing the services they need and even the applications they need. The service providers must produce services that are in need. This new paradigm extends the design and code sharing, and thus further improves the software productivity. This paper presents the concepts, architecture, enabling techniques, and illustrative examples.","Title: A Security Authentication Protocol for Trusted Domains in an Autonomous Decentralized System\nYear: 2016\n\nAbstract: AbstractSoftware Defined Network SDN architecture has been widely used in various application domains. Aiming at the authentication and security issues of SDN architecture in autonomous decentralized system ADS applications, securing the mutual trust among the autonomous controllers, we combine trusted technology and SDN architecture, and we introduce an authentication protocol based on SDN architecture without any trusted third party between trusted domains in autonomous systems. By applying BAN predicate logic and AVISPA security analysis tool of network interaction protocol, we can guarantee protocol security and provide complete safety tests. Our work fills the gap of mutual trust between different trusted domains and provides security foundation for interaction between different trusted domains.","Title: Analyzing and visual programming internet of things and autonomous decentralized systems.\nYear: 2016\n\nAbstract: The development of Internet of Things, fueled by cloud computing and big data processing from upper level, and by ubiquitous sensory and actuator devices from the lower level, has taken a sharp turn towards integrating the entire information, computing, communication, and control systems. This special issue selected seven papers from the 2015 IEEE twelfth International Symposium on Autonomous Decentralized Systems (ISADS). These papers cover the latest research on IoT and ADS based system science and system engineering methods; the wearable sensor network development and applications; and data analysis for security and reliability in IoT and ADS applications. As an addition to these selected topics, this guest editorial paper also adds IoT education and dissemination aspects to this special issue. As the IoT research and applications expand explosively into all the domains, schools and universities must prepare students to understand and to be able to program the IoT devices. This paper presents a visual programming environment that allows students without programming background to learn the key concepts of computing and IoT devices, and to program IoT devices into different application systems.","Title: A Novel Multi-Focus Image Fusion Method Based on Stochastic Coordinate Coding and Local Density Peaks Clustering.\nYear: 2016\n\nAbstract: The multi-focus image fusion method is used in image processing to generate all-focus images that have large depth of field (DOF) based on original multi-focus images. Different approaches have been used in the spatial and transform domain to fuse multi-focus images. As one of the most popular image processing methods, dictionary-learning-based spare representation achieves great performance in multi-focus image fusion. Most of the existing dictionary-learning-based multi-focus image fusion methods directly use the whole source images for dictionary learning. However, it incurs a high error rate and high computation cost in dictionary learning process by using the whole source images. This paper proposes a novel stochastic coordinate coding-based image fusion framework integrated with local density peaks. The proposed multi-focus image fusion method consists of three steps. First, source images are split into small image patches, then the split image patches are classified into a few groups by local density peaks clustering. Next, the grouped image patches are used for sub-dictionary learning by stochastic coordinate coding. The trained sub-dictionaries are combined into a dictionary for sparse representation. Finally, the simultaneous orthogonal matching pursuit (SOMP) algorithm is used to carry out sparse representation. After the three steps, the obtained sparse coefficients are fused following the max L1-norm rule. The fused coefficients are inversely transformed to an image by using the learned dictionary. The results and analyses of comparison experiments demonstrate that fused images of the proposed method have higher qualities than existing state-of-the-art methods.","Title: A trusted access method in software-defined network.\nYear: 2017\n\nAbstract: In software-defined networks (SDN), most controllers do not have an established control function for endpoint users and access terminals to access network, which may lead to many attacks. In order to address the problem of security check on access terminals, a secure trusted access method in SDN is designed and implemented in this paper. The method includes an access architecture design and a security access authentication protocol. The access architecture combines the characteristics of the trusted access technology and SDN architecture, and enhances the access security of SDN. The security access authentication protocol specifies the specific structure and implementation of data exchange in the access process. The architecture and protocol implemented in this paper can complete the credibility judgment of the access device and user's identification. Furthermore, it provides different trusted users with different network access permissions. Experiments show that the proposed access method is more secure than the access method that is based on IP address, MAC address and user identity authentication only, thus can effectively guarantee the access security of SDN.","Title: Robot Cloud: Bridging the power of robotics and cloud computing.\nYear: 2017\n\nAbstract: Cloud computing is shaping the cyber world and evolves as a key computing and service platform for sharing resources including platforms, software applications and everything in the form of services. This is known “X as a Service”. Although it brings our age unparalleled computing ability and economic benefits, the application of cloud computing is still limited currently in the cyberspace due to the cloud services can only reside in cloud instead of our daily life environment. In fact, there are still a plethora of physical position based on-site service demands that cloud computing could help little due to the “cyber limitation”. In this paper, we aim to integrate the cyber world and the physical world by bringing up the idea of “Robot Cloud” to bridge the power of robotics and cloud computing. To make it possible, we design a novel Robot Cloud stack to support our idea and adopt the service-oriented architecture (SOA) to make the functional modules in the Robot Cloud more flexible, extensible and reusable. Then we develop a prototype of Robot Cloud using the popular Google App Engine to demonstrate our design method. Finally, we conduct the simulation experiments with a “robot show” application scenario to evaluate our scheduling policy and identify the effect of different request distributions and robot center solutions.","Title: A Distributed Proactive Service Framework for Crowd-Sensing Process\nYear: 2017\n\nAbstract: With the wide deployment of various kinds of sensors in fixed infrastructures and in mobile devices, technologies and applications of crowd-sensing has drawn attentions in the fields of mobile computing. This paper studies the design of frameworks for crowd-sensing process in a distributed environment. We discuss the realization of the compatibilities of devices and services, as well as the algorithms of dealing with transmitting and accessing large amount of sensing data. We present a new distributed crowd-sensing framework called DASF, which is based on context data servers. The framework consists of three layers: hardware device layer, context data layer, and smart service layer. The key innovations and features of the framework are illustrated in detail. Through experiments and results analyses, DASF is shown to have good compatibility in heterogeneous device platforms, and it is capable of dealing with heavy load of accessing with practical significance.","Title: Dynamic Resource Allocation Algorithm for Container-Based Service Computing\nYear: 2017\n\nAbstract: Cloud computing and virtualization technologies play important roles in modern service-oriented computing paradigm. More conventional services are being migrated to virtualized computing environments to achieve flexible deployment and high availability. We introduce a schedule algorithm based on fuzzy inference system (FIS), for global container resource allocation by evaluating nodes' statuses using FIS. We present the approaches to build containerized test environment and validates the effectiveness of the resource allocation policies by running sample use cases. Experiment results show that the presented infrastructure and schema derive optimal resource configurations and significantly improves the performance of the cluster.","Title: Robot as a Service in Information Science & Electronic Engineering Education\nYear: 2017\n\nAbstract: This paper reports the newly designed programming course developed and taught at Zhejiang University for a freshman class majoring in information science and electronic engineering, and disseminated to many other universities, to address the enrollment crisis as reported by ACM Curriculum Committee Review Task Force. The course teaches the basic information science and electronic engineering concepts and gives the students practical programming experience through robotics programming. The initial curriculum and the ongoing improvement of the course are presented. The course started with its experiment environment using ASU Visual IoT/Robotics Programming Environment (VIPLE). The environment supports a variety of platforms, including open architecture-based robots, such as Intel robots, PCDuino robots, vendor-specific robots, such as Lego EV3, as well as simulated robots, such as Web simulated robots in HTML5 and Unity-based 3D robots.","Title: Visual IoT/Robotics Programming Language in Pi-Calculus\nYear: 2017\n\nAbstract: As IoT/robotics research and applications expand explosively into many domains in computing, information, and control systems, schools and universities must prepare students to understand and be able to program IoT devices and robots. However, programming IoT and physical devices is hard and depends on good understanding of hardware and low-level programming. Workflow and visual programming environments have been developed to address this issue, including MIT App Inventor, Microsoft Robotics Developer Studio and VPL (Visual Programming Language), and Intel Service Orchestration Layer. We have developed a new visual programming language and its development environment: ASU VIPLE (Visual IoT/Robotics Programming Language Environment). ASU VIPLE is specifically developed to support different device platforms. It supports LEGO EV3 and all IoT devices based on an open architecture. ASU VIPLE integrates engineering design process, workflow, fundamental programming concepts, control flow, parallel computing, and event-driven programming seamlessly into the curriculum. It has been pilot tested at Arizona State University in summers 2015 and 2016, and is now taught in an ASU regular class, Introduction to Engineering. It has been adopted by numerous universities around the world. This paper focuses on the mathematical model of ASU VIPLE. π-calculus is used to describe the basic activities in VIPLE, as well as the workflow defined by the basic activities.","Title: Fault-diagnosis for reciprocating compressors using big data and machine learning.\nYear: 2018\n\nAbstract: Reciprocating compressors are widely used in petroleum industry. A small fault in reciprocating compressor may cause serious issues in operation. Traditional regular maintenance and fault diagnosis solutions cannot efficiently detect potential faults in reciprocating compressors. This paper proposes a fault-diagnosis system for reciprocating compressors. It applies machine-learning techniques to data analysis and fault diagnosis. The raw data is denoised first. Then the denoised data is sparse coded to train a dictionary. Based on the learned dictionary, potential faults are finally recognized and classified by support vector machine (SVM). The system is evaluated by using 5-year operation data collected from an offshore oil corporation in a cloud environment. The collected data is evenly divided into two halves. One half is used for training, and the other half is used for testing. The results demonstrate that the proposed system can efficiently diagnose potential faults in compressors with more than 80% accuracy, which represents a better result than the current practice.","Title: Morphology-based visible-infrared image fusion framework for smart city.\nYear: 2018\n\nAbstract: Sparse representation-based approaches are often applied to image fusion. Owing to the difficulties of obtaining a complete and non-redundant dictionary, this paper proposes a hierarchical image fusion framework that applies layer-by-layer deep learning techniques to explore the detailed information of images and extract key information of images for dictionary learning. According to morphological similarities, this paper clusters source image patches into smooth, stochastic, and dominant orientation patch group. High-frequency and low-frequency components of three clustered image-patch groups are fused by max-L1 and L2-norm based weighted average fusion rule respectively. The fused low-frequency and high-frequency components are combined to obtain the final fusion results. The comparison experimentations confirm the feasibility and effectiveness of the proposed image fusion solution.","Title: Tenant-centric Sub-Tenancy Architecture in Software-as-a-Service\nYear: 2016\n\nAbstract: Multi-tenancy architecture (MTA) is often used in Software-as-a-Service (SaaS) and the central idea is that multiple tenant applications can be developed using components stored in the SaaS infrastructure. Recently, MTA has been extended to allow a tenant application to have its own sub-tenants, where the tenant application acts like a SaaS infrastructure. In other words, MTA is extended to STA (Sub-Tenancy Architecture). In STA, each tenant application needs not only to develop its own functionalities, but also to prepare an infrastructure to allow its sub-tenants to develop customized applications. This paper applies Crowdsourcing as the core to STA component in the development life cycle. In addition, to discovering adequate fit tenant developers or components to help build and compose new components, dynamic and static ranking models are proposed. Furthermore, rank computation architecture is presented to deal with the case when the number of tenants and components becomes huge. Finally, experiments are performed to demonstrate that the ranking models and the rank computation architecture work as design.","Title: Technologies for developing a smart city in computational thinking.\nYear: 2018\n\nAbstract: Building a smart city involves almost all the aspects of social, economic, and technological issues. This paper gives a brief survey and overview of the latest technologies for building a smart city. It covers IoT, device as a service, service-oriented computing and cloud computing as the infrastructure, big data analysis and processing for data mining, and artificial intelligence. A visual programming language for IoT and robotics application development is also introduced, which offers a tool for architects and developers to define the applications using computational thinking and workflow of existing services and components.","Title: Visual programming language environment for different IoT and robotics platforms in computer science education\nYear: 2018\n\nAbstract: This study presents the authors’ recent research and application of a new visual programming language and its development environment: VIPLE (Visual IoT/Robotics Programming Language Environment) at Arizona State University (ASU). ASU VIPLE supports a variety of IoT devices and robots based on an open architecture. Based on computational thinking, VIPLE supports the integration of engineering desi...","Title: Modeling and simulation of improved artificial bee colony algorithm with data-driven optimization\nYear: 2019\n\nAbstract: •This paper studies the driving force of additional data for ABC.•An improved artificial bee colony algorithm with data-driven is proposed.•The searching process is driven by directional guiding data and local data.•Our work is compared with some ABC-based and nature-inspired algorithms.","Title: A Spark-Based Open Source Framework for Large-Scale Parallel Processing of Rich Text Documents\nYear: 2021\n\nAbstract: The large amount of unstructured educational data is an important data source of educational big data analysis. However, there is a lack of efficient and simple distributed solutions to process these unstructured documents. To address this problem, this study proposes a Spark-based parallel processing framework of large-scale rich text documents (mainly as MS Word documents), which can seamlessly ...","Title: Twe-Wsd: An Effective Topical Word Embedding Based Word Sense Disambiguation\nYear: 2021\n\nAbstract: Word embedding has been widely used in word sense disambiguation (WSD) and many other tasks in recent years for it can well represent the semantics of words. However, the existing word embedding methods mostly represent each word as a single vector, without considering the homonymy and polysemy of the word; thus, their performances are limited. In order to address this problem, an effective topical word embedding (TWE)-based WSD method, named TWE-WSD, is proposed, which integrates Latent Dirichlet Allocation (LDA) and word embedding. Instead of generating a single word vector (WV) for each word, TWE-WSD generates a topical WV for each word under each topic. Effective integrating strategies are designed to obtain high quality contextual vectors. Extensive experiments on SemEval-2013 and SemEval-2015 for English all-words tasks showed that TWE-WSD outperforms other state-of-the-art WSD methods, especially on nouns.","Title: Multi-view 3D model retrieval based on enhanced detail features with contrastive center loss\nYear: 2022\n\nAbstract: In recent years, 3D model retrieval has become a hot topic. With the development of deep learning technology, many state-of-the-art deep learning based multi-view 3D model retrieval algorithms have emerged. One of the major challenges in view-based 3D model retrieval is how to achieve rotation invariant. MVCNN (Multi-View Convolutional Neural Networks) achieving higher performance while maintaining rotation invariant. However, the element-wise maximum operation across the views leads to the loss of detailed information. To address this problem, in this paper, we use a deep cross-modal learning method to treat the features of different views as different modal features. First, we select two of the views as the input of the deep multimodal learning method. Then we combine the proposed method with an improved contrastive center loss, so that we can align the features in the same subspace and obtain a higher discriminative fused feature. Experimental results show that the training of the proposed CNN (Convolutional Neural Networks) model is based on the existing MVCNN pre-trained model, which takes only 18 epochs to converge, and it obtains 90.07% in terms of mAP (mean average precision) using only the MVCNN as the backbone, which is comparable to the feature fusion algorithm PVRNet (Point-View Relation Neural Network) and much higher than the mAP of MVCNN (80.2%). The experimental results demonstrated that the proposed method avoids explicitly learning the weights for fusion of different view features, while incorporating more details into the 3D model’s final descriptor can improve the retrieval results.","Title: Multi-head self-attention based gated graph convolutional networks for aspect-based sentiment classification\nYear: 2022\n\nAbstract: Aspect-based sentiment classification aims to predict the sentiment polarity of specific aspects appeared in a sentence. Nowadays, most current methods mainly focus on the semantic information by exploiting traditional attention mechanisms combined with recurrent neural networks to capture the interaction between the contexts and the targets. However, these models did not consider the importance of the relevant syntactical constraints. In this paper, we propose to employ a novel gated graph convolutional networks on the dependency tree to encode syntactical information, and we design a Syntax-aware Context Dynamic Weighted layer to guide our model to pay more attention to the local syntax-aware context. Moreover, Multi-head Attention is utilized for capturing both semantic information and interactive information between semantics and syntax. We conducted experiments on five datasets and the results demonstrate the effectiveness of the proposed model.","Title: Bayesian estimation-based sentiment word embedding model for sentiment analysis\nYear: 2022\n\nAbstract: Sentiment word embedding has been extensively studied and used in sentiment analysis tasks. However, most existing models have failed to differentiate high-frequency and low-frequency words. Accordingly, the sentiment information of low-frequency words is insufficiently captured, thus resulting in inaccurate sentiment word embedding and degradation of overall performance of sentiment analysis. A Bayesian estimation-based sentiment word embedding (BESWE) model, which aims to precisely extract the sentiment information of low-frequency words, has been proposed. In the model, a Bayesian estimator is constructed based on the co-occurrence probabilities and sentiment probabilities of words, and a novel loss function is defined for sentiment word embedding learning. The experimental results based on the sentiment lexicons and Movie Review dataset show that BESWE outperforms many state-of-the-art methods, for example, C&W, CBOW, GloVe, SE-HyRank and DLJT1, in sentiment analysis tasks, which demonstrate that Bayesian estimation can effectively capture the sentiment information of low-frequency words and integrate the sentiment information into the word embedding through the loss function. In addition, replacing the embedding of low-frequency words in the state-of-the-art methods with BESWE can significantly improve the performance of those methods in sentiment analysis tasks.","Title: Polymorphic graph attention network for Chinese NER\nYear: 2022\n\nAbstract: •Lexicon information has been proved to be very useful in Chinese Named Entity task.•The existing methods make insufficient use of lexicon information.•We propose a Polymorphic Graph Attention Network for fusion lexicon into character.•Our method can be easily combined with pre-trained or sequence encoding model.•The proposed method supports multi-head attention and has excellent inference speed."],"string":"[\n \"Title: Collaborative Learning Using Wiki Web Sites for Computer Science Undergraduate Education: A Case Study\\nYear: 2011\\n\\nAbstract: This paper proposes a collaborative approach to enhancing the student learning experience based on Web 2.0 principles. Specifically, wiki Web sites are used by students for collaboration and for publication of course assignments, which are then shared with the class. Web 2.0 principles include: the Web as platform, harnessing collective intelligence, data are the next Intel Inside, and rich user experiences. Based on a case study in a junior-level undergraduate class, this paper studies a set of six factors with comprehensive grading and evaluation criteria that are critical to make this approach successful. The six factors are knowledge base, motivation, research, social aspects, presentation, and feedback and support. The data collected show that most of the students who participated feel that this approach is exciting and rewarding, and that even some undergraduate students are able to produce original and innovative concepts. The data also show other interesting phenomena with respect to motivation, undergraduate research, and social aspects. Finally, the paper proposes a methodology of conducting a wiki project in a university class using a cyclic constant improvement process.\",\n \"Title: RTSOA: Real-Time Service-Oriented Architecture\\nYear: 2006\\n\\nAbstract: This paper extends the traditional Service-Oriented Architecture (SOA) to a new Real-Time SOA (RTSOA) and proposes a framework for the new architecture, by providing real-time service modeling, design, code generation, simulation, deployment, execution, orchestration, and management. The concepts, architecture, and enabling technique are studied for Real-time SOA. In addition, an efficient algorithm is derived in the paper to find the optimal composition of real-time services subject to the real-time constraint.\",\n \"Title: On an Automatic Simulation Environment Customizing Services for Cloud Simulation Center\\nYear: 2010\\n\\nAbstract: Simulation plays an important role in both academic research and industrial development and manufactory. The users’ requirements for simulation are often complex and diverse. It is time consuming and error-prone for users to build different simulation environments manually to conduct their simulation tasks. An Automatic Simulation Environment Customiz卢ing Service for Cloud Simulation Center is presented in this paper to address this problem. The service offers an automatic simulation environment that can customize and configure service requirements of simulation users with high efficiency, flexibility and agility. The system is capable of processing diversified requests dynamically and responding the requests in real-time. The operation and experiments on the prototype system operation and experiment show higher availability, flexibility, and reusability of our method than the traditional simulation environment customizing method.\",\n \"Title: Distributed Policy Specification and Enforcement in Service-Oriented Business Systems\\nYear: 2005\\n\\nAbstract: Service-Oriented Computing (SOC) and Web Services (WS) provide a flexible computing platform for electronic business and commerce. Introducing policy-based computing to service-oriented business systems adds another dimension of flexibility and security. While service composition and re-composition in service-oriented business systems allow major system reconstruction, policy-based computing can better deal with the small and routine changes of business processing. This paper reports our latest research on integrating policy-based computing into service-oriented business system and discusses its feasibility, benefits and cost. Under this research, we designed a policy specification and enforcement language PSEL for specifying system constraints and business rules. We implemented a runtime environment in which a service-oriented business system can be modeled, analyzed, deployed, and executed with policy enforcement. Automated tools have been developed to facilitate the entire development process. The cost of policy-based computing is experimentally evaluated.\",\n \"Title: A SOA Based Pipeline System to Deal with Astronomy Telescope Data\\nYear: 2006\\n\\nAbstract: In order to deal with telescope data more systematically and flexibly, this paper proposes a grid middleware pipeline system PMGrid based on serviceoriented architecture (SOA) for efficient telescope data processing. This system allows users to dynamically compose data process application as a Pipeline Virtual Service (PVS) using existing services for their special purposes. Furthermore, the configured PVS has the standard interface as services and can be published in PMGrid system as a single unit of service shared and reused by other users. Grid technologies and Web service technologies are aligned with each other in this system through standard-based interface and protocols. Based on SOA, the PMGrid system can provide not only more telescope data process functions to satisfy users' special purposes, but also more shared public functions. Combing SOA and Grid, the PMGrid system is portable and has advantages in reducing cost and increasing the services utilization. This paper presents the design, analysis, and implementation of the PVS subsystem in the telescope data processing system.\",\n \"Title: Secondary-diagonal mean transformation Partial Grey Model based on matrix series.\\nYear: 2012\\n\\nAbstract: Grey Model (GM) deals with the systems where certain information about the systems is unknown or incomplete. GM has been successfully used in many engineering areas, including agriculture, energy, economy, and environmental engineering where prediction needs to be made with uncertain factors. Particularly, GM is widely applied in image processing and data filtering. In a GM defined by matrix series, the prediction is made by solving these matrixes through a sequence of matrix operations. To improve the simulation and prediction accuracy of GM matrix solving, a novel secondary-diagonal mean transformation Partial GM (mtP-GM) is developed in this paper. We first defined a mean transformation in the secondary-diagonal direction of the matrix series. We then defined the mtP Accumulating Generation Operation (mtP-AGO) according to the principles of AGO, matrix-AGO (m-AGO), and Partial-AGO (P-AGO). The principles of GM are followed in the modeling process, and grey impact factors of the model are encapsulated in a matrix with m2 unknown elements. Finally, four real data sets with long-running data and multi-stream series are imported for comparing the performance of the developed mtP-GM with several other grey models, such as RGM, dtP-GM, and GM(1,1). The comparison results show that dtP-GM can obtain a better accuracy for periodic data sequences. However, our mtP-GM outperforms the other three models for non-periodic data sequences.\",\n \"Title: A New SOA Data-Provenance Framework\\nYear: 2007\\n\\nAbstract: Due to the dynamic nature, such as runtime composition and evaluation, it is critical for an SOA system to consider its data provenance, which concerns security, reliability, and integrity of data as it is routed in the system. In a traditional software system, one can focus on the software itself to determine the security, reliability, and integrity; however, in an SOA system, one also needs to consider the origins and routes of data and their impact, i.e., data provenance. This paper first analyzes the unique natures and characteristics of data provenance in an SOA system. Then it proposes a new framework to classify data provenance and collect data in SOA systems. Finally, this paper uses an example to illustrate these concepts and techniques.\",\n \"Title: Adaptive Web Services Testing\\nYear: 2007\\n\\nAbstract: Web Services (WS) and Service-Oriented Architecture (SOA) present a set of unique testing challenges. As services are distributed, it is necessary to test them using a distributed architecture. Furthermore, as these services may keep on changing, testing needs to be adaptive. This paper proposes an adaptive testing framework which can continuously learn and improve the built-in test strategies. The framework allows different test cases to be selected based on the recent test results. The framework also has a windowing mechanism to evaluate and select test cases. . .\",\n \"Title: An Index Clustering and Mapping Algorithm for Large Scale Astronomical Data Searching\\nYear: 2009\\n\\nAbstract: For large scale unstructured astronomical data documents, the simple index method often results in high communication cost and slow query processing. Based on the characteristics of domain specific astronomical data and the quantitative tracing and analyzing results, a query terms similarity calculation formula is provided. An index clustering algorithm is designed to generate many small clusters with high term association and small real index size which can be stored into different nodes as a whole. To keep high query locality and reasonable load balancing, a practical index mapping algorithm is proposed to map different logical index clusters onto physical nodes. The simulation results show that the algorithms provided in this paper have good scalability for large scale astronomical data index system. Compared with other methods, different queries can be distributed and located onto smaller number of nodes, so communication cost among different nodes can be reduced significantly and the search efficiency could be well improved.\",\n \"Title: A simulation cloud monitoring framework and its evaluation model.\\nYear: 2013\\n\\nAbstract: •A framework is provided to design the monitoring system of Simulation Cloud.•Two strategies are provided to reduce monitoring cost and balance load.•An evaluation model is developed to check its feasibility.\",\n \"Title: Collaborative Web Services Monitoring with Active Service Broker\\nYear: 2008\\n\\nAbstract: This paper proposes a collaborative runtime monitoring framework to enhance the dependability of the software developed in traditional Web services architecture. The enabling mechanism is an active service broker (ASB) architecture which allows the service broker not only to serve as a passive service repository, but also to involve itself in service interactions and thus to play an active role in service execution and monitoring. The ASB communicates remotely with the distributed monitoring agents deployed at the service providerspsila sites. Sensors are instrumented in services at different levels, including the composition level, interface level, and component level. The model-based approach is discussed for automatic sensor generation and runtime enforcement based on service's process model and verification model. A prototype is implemented for the research of the user and science data center of the astronomic satellite system at Tsinghua University.\",\n \"Title: Verification Framework for Dynamic Collaborative Services in Service-Oriented Architecture\\nYear: 2006\\n\\nAbstract: This paper introduces a dynamic verification framework for collaborative services in Service- Oriented Architecture (SOA). Collaboration plays a critical role in SOA, an effective verification framework for collaboration will greatly reduce the effort for rapid and adaptive service composition and evaluation of applications based on collaborative services. The verification framework provides a service-oriented infrastructure for completeness and consistency analyses, model-checking, simulation, and policy enforcement of process specification based on collaborative services in SOA. The paper presents the concepts, architecture, profiling techniques and illustrative examples that demonstrate the concepts and the techniques.\",\n \"Title: Teaching Service-Oriented Computing and STEM Topics via Robotic Games\\nYear: 2008\\n\\nAbstract: The ever-increasing functionality and the non-functional constraints that must be satisfied by embedded systems lead to an enormous growth in the complexity at the system level. In this paper we investigate the notion of cognitive complexity and argue ...\",\n \"Title: Event-driven service-oriented simulation framework\\nYear: 2010\\n\\nAbstract: Service-oriented architecture (SOA) and event-driven architecture (EDA) have received significant attention recently. This paper presents an event-driven service-oriented simulation framework that combines both features of SOA and EDA and it can be used to evaluate embedded applications. The framework allows events, event generators, and event handlers to be published, discovered, and composed to develop an event-driven system, furthermore these can be seamlessly integrated into the existing SOA framework where publishing, discovery, composition and runtime monitoring are key features. This paper also uses PSML (Process Specification and Modeling Language) [1] to specify events. Finally, this paper uses an embedded system to illustrate the framework.\",\n \"Title: A stepwise optimization algorithm of clustered streaming media servers\\nYear: 2009\\n\\nAbstract: The optimization of Clustered Streaming Media Servers (CSMS), which aims at using as few hardware resources and as cost-effective as possible, while providing satisfactory performance and QoS, has a great impact on the practicability and efficiency of CSMS. Based on the analysis and formulization of critical performance factors of CSMS and the relationship among the performance, QoS, and the costs in CSMS, a stepwise optimization algorithm is developed to solve the optimization problem efficiently. The algorithm is based on an approach that models the optimization problem into a directed acyclic graph and then addresses the complex optimization problem step by step. The algorithm applies a divide and conquer model that not only reduces the complexity of the optimization problem, but also accelerates the optimization process. Progressive information is collected in the process and used in solving the problem. Furthermore, a simulation system of CSMS is necessary for the optimization algorithm to generate the accurate information produced in the entire streaming service process. Thus, we designed and implemented such a simulation system based on the theoretical performance model of CSMS and the parameters measured in practical CSMS testbed. Finally, a case study of the optimization problem is given to demonstrate the process of the algorithm, and an appropriate plan for designing practical CSMS system is illustrated.\",\n \"Title: Global Software Enterprise: A New Software Constructing Architecture\\nYear: 2006\\n\\nAbstract: Based on current Service-Oriented Architecture (SOA), this paper introduces a consumer-oriented SOA software constructing architecture: the Global Software Enterprise (GSE) architecture. In this architecture, the software construction starts from the consumers' publishing their requirements in the form of application or service specification which they exactly want. The consumer also publishes the expectation for the services the application needs in the form of collaboration specification and test scripts. The service providers then produce services that meet the needs of the applications. This new approach reduces the workload for the consumer and the communication between the consumer and provider. It also extends the design and code sharing, and thus further improves the software productivity.\",\n \"Title: Performance Simulation of a Dependable Distributed System\\nYear: 2001\\n\\nAbstract: The aim of our research is to develop a distributed system platform that supports a variety of tasks. Currently, we are implementing Internet applications on the system, including a service redirector, firewall, and web applications. These applications have different levels of dependability requirements. Depending on their criticality, a single task may execute on one or more computer nodes. Software-implemented fault-tolerant protocols are used to detect the disagreement among replicas. A reconfiguration protocol is used to identify faulty nodes according to the fault reports from other fault-tolerant protocols and to reallocate their tasks to other working nodes. As a part of the project, this work focuses on the implementation and simulation of the system and the firewall application. Data transfer throughput of the system is measured and analyzed. The results are being used in supporting our development of the overall system.\",\n \"Title: Automated Model Checking and Testing for Composite Web Services\\nYear: 2005\\n\\nAbstract: Web Services form a new distributed computing paradigm. Collaborative verification and validation are important when Web Services from different vendors are integrated together to carry out a coherent task. This paper presents a new approach to verify Web Services by model checking the process model of OWL-S (Web Ontology Language for Web Services) and to validate them by the test cases automatically generated in the model checking process. We extend the BLAST, a model checker that handles control flow model naturally, to handle the concurrency in OWL-S. We also propose enhancement in OWL-S and PDDL (Planning Domain Definition Language) to facilitate the automated test case generation. Experiments on realistic examples are provided to illustrate the process.\",\n \"Title: Scheduling Simulation in a Distributed Wireless Embedded System\\nYear: 2005\\n\\nAbstract: The aims of the research are to develop a distributed simulation environment and to investigate techniques that support efficient task-scheduling algorithms in fault-tolerant, real-time, distributed, and wireless embedded systems. Techniques developed include deadline-based real-time scheduling, priority-based scheduling, and redundant resource allocation for fault-tolerant, energy-aware, and signal strength-aware scheduling. A system model is proposed, and a prototype of the distributed simulation environment is implemented. Three scheduling algorithms and sample applications are designed and implemented in the environment. Experiment data are collected for analyzing the effectiveness of the algorithms.\",\n \"Title: An autonomic provisioning framework for outsourcing data center based on virtual appliances\\nYear: 2008\\n\\nAbstract: As outsourcing data centers emerge to host applications and services from many different organizations, it is critical for data center owners to isolate different applications while dynamically and optimally allocate sharable resources among them. To address this issue, we propose a virtual-appliance-based autonomic resource provisioning framework for large virtualized data centers. We present the architecture of the data center with enriched autonomic features. We define a non-linear constrained optimization model for dynamic resource provisioning and present a novel analytic solution. Key factors, including virtualization overhead and reconfiguration delay, are incorporated into the model. Experimental results based on a prototype demonstrate that the system-level performance has been greatly improved by taking advantage of fine-grained server consolidation, and the whole system exhibits flexible adaptation in failure scenarios. Experiments with the impact of switching delay also show the efficiency of the framework due to significantly reduced provisioning time.\",\n \"Title: Dynamic Dataflow Driven Service Composition Mechanism for Astronomy Data Processing\\nYear: 2007\\n\\nAbstract: Although some relatively mature products and systems about Dynamic service composition are proposed, their manipulations are mostly not trivial and intuitive for the common users. Therefore, this paper proposes a dataflow driven dynamic service composition architecture aiming at astronomy applications, to simplify the requirements for users to compose a service. The architecture utilizes Dataflow Driven conception to discover an Original Topology Graph, which includes the final composite service with the shortest length and good parallel structure, and uses a Converse Composition algorithm to ascertain the final result quickly. This architecture is applied in the PMGrid prototype for astronomy data processing, and the experiment results show the architecture satisfies the parallelism and asynchrony in distributed system, avoids manual errors, increases the service configuring efficiency, provides the composite service with better structure to increase the executing parallelism, and finally improve the scientific discovery.\",\n \"Title: Adaptive Testing, Oracle Generation, and Test Case Ranking for Web Services\\nYear: 2005\\n\\nAbstract: Web services and service-oriented architecture are emerging technologies that are changing the way we develop and use computer software. Due to the standardization of web services related description languages and protocols, as well as the open platforms, for the same web service specification, many different implementations can be offered from different service providers. This paper presents an adaptive group testing technique that can test large number web services simultaneously and effectively. Based on a case study, experiments are performed to validate the correctness and effectiveness of the technique.\",\n \"Title: Architecture Classification for SOA-Based Applications\\nYear: 2006\\n\\nAbstract: The architecture of SOA-based applications is different from traditional software architecture where the architecture is mainly static. The architecture of an SOA-based application is dynamic, i.e., the application may be composed at runtime using existing services. Thus SOA has provided a new direction for software architecture study, where the architecture is determined at runtime and architecture can be dynamically changed at runtime to meet the new software requirements. This paper proposes an architecture classification scheme for SOA-based applications. Using this classification, several wellknown SOA-based applications are reviewed including the architectures proposed and adopted by major computer companies and standard organizations. The architecture classification provides a unified way to evaluate a variety of architectures for SOA-based applications.\",\n \"Title: Designing a Service-Oriented Computing Course for High Schools\\nYear: 2007\\n\\nAbstract: Service-Oriented Computing (SOC) is becoming the dominating paradigm for software development in many areas, including e-business, robotics, gaming, and scientific computation. One of the key issues lagging behind is the education. In spite of significant progress in SOC applications, SOC education has not been taught in introductory classes. Existing SOC courses are graduate or senior-level courses in universities that require full programming background. While various issues regarding SOC are being explored and discussed, the issues for SOC education, especially at high school level, still remain uncultivated, which does not match up with the importance of SOC paradigm. Sponsored by U.S. Department of Education, the Computer Science & Engineering Department and the College of Education at Arizona State University, in cooperation with Scottsdale Unified School District and Coronado High School, we pioneered the first SOC course for high school students in Spring 2007. The same course was taught to high school teachers in summer 2007, and the service-oriented robotics development part was taught to high school students in a summer camp in 2007. This paper discusses the design of the course and reports the experience and lessons in teaching these classes.\",\n \"Title: Ontology-Based Test Modeling and Partition Testing of Web Services\\nYear: 2008\\n\\nAbstract: Testing is useful to establish trust between service providers and clients. To test the service-oriented applications, automated and specification-based test generation and test collaboration are necessary. The paper proposes an ontology-based approach for Web Services (WS) testing. A Test Ontology Model (TOM) is defined to specify the test concepts, relationships, and semantics from two aspects: test design (such as test data, test behavior, and test cases) and test execution (such as test plan, schedule and configuration). The TOM specification using OWL (Web Ontology Language) can serve as test contracts among test components. Based on the WS semantic specification in OWL-S, the paper discusses the techniques to generate the sub-domains for input partition testing. Data pools are established for each parameter of the specified service. Data partitions are derived by class property and relationship analysis. Completeness and consistency (C&C) checking can be performed on the data partitions and data values, both within the TOM and against the OWL-S, by ontology class computation and reasoning. A prototype tool is implemented to support OWL-S analysis, test ontology generation and C&C checking.\",\n \"Title: Optimized QoS-aware replica placement heuristics and applications in astronomy data grid\\nYear: 2011\\n\\nAbstract: This paper studies the Quality-of-Service (QoS)-aware replica placement problem in a general graph model. Since the problem was proved NP-hard, heuristic algorithms are the current solutions to the problem. However, these algorithms cannot always find the effective replica placement strategy. We propose two algorithms that can obtain better results within the given time period. The first algorithm is called Cover Distance algorithm, which is based on the Greedy Cover algorithm. The second algorithm is an optimized genetic algorithm, in which we use random heuristic algorithms to generate initial population to avoid enormous useless searching. Then, the 0-Greedy-Delete algorithm is used to optimize the genetic algorithm solutions. According to the performance evaluation, our Cover Distance algorithm can obtain relatively better solution in time critical scenarios. Whereas, the optimized genetic algorithm is better when the replica cost is of higher priority than algorithm execution time. The QoS-aware data replication heuristic algorithms are applied into the data distribution service of an astronomy data grid pipeline prototype, and the operation process is studied in detail.\",\n \"Title: Simulation Verification and Validation by Dynamic Policy Specification and Enforcement\\nYear: 2006\\n\\nAbstract: This article presents a new verification and validation technique for simulation using dynamic policy specification and enforcement. Security requirements, certain functional requirements, and constraints can be formally specified as policies, and they are used to check at runtime whether the behaviors of the system under simulation are within the given constraints. A policy violation reveals a potential design error of the system under simulation. This article also presents the policy specification language and the policy development framework that are used to specify policies, to verify their completeness and consistency of policies, to translate them into executable representations, and to enforce them at runtime. The policy specification language and the policy development framework are fully integrated into the simulation infrastructure. An example is used throughout the article to illustrate the policy specification and enforcement processes. The article discusses different algorithms of policy enforcement and their space and time complexity.\",\n \"Title: QoS Enhancement for PDES Grid Based on Time Series Prediction\\nYear: 2007\\n\\nAbstract: The combination of parallel/distributed discrete event simulation (PDES) and Grid technology is a new trend in simulation. QoS is important yet difficult in this process. With the special features of Gird architecture and PDES input, such as periodical and predictable inputs, we could enhance QoS with a PDES-specific prediction. A Grid-based framework is presented that is designed to help predict the performance of PDES. Based on this framework, a prediction algorithm using time series theory is presented in the context of large scale Grid simulations. Experiments are executed in the context of GridSim, which shows methods discussed before to help to improve QoS level.\",\n \"Title: A service scheduler in a trustworthy system\\nYear: 2004\\n\\nAbstract: The aim of the research is to investigate techniques that support efficient service scheduling algorithms in a service-oriented fault-tolerant real-time distributed system. Techniques we developed include deadline-based real-time scheduling, priority-based scheduling, and redundant resource allocation for fault-tolerance. The system model and scheduling algorithms are designed, and a prototype is implemented to facilitate the investigation and experimentation.\",\n \"Title: A software reliability model for web services\\nYear: 2004\\n\\nAbstract: This paper proposes a service-oriented software reliability model that dynamically evaluates the reliability of Web services. There are two kinds of Web services: atomic services without the structural information and the composite services consisting of atomic services. The model first evaluates the reliability of atomic services based on group testing and majority voting. Group testing is the key technique proposed in this paper to support the service-oriented reliability model. Then, the reliability model evaluates the overall reliability of composite services using an architecture-based model and based on reliabilities of the atomic services, execution scenarios, and operational profiles. The reliability model is dynamic and the reliabilities of the services are evaluated in the actual operational environment. A case study is designed, implemented, and analyzed using the design of experiment technique. The results show the significances of the model and its components.\",\n \"Title: Dependability modelling of homogeneous and heterogeneous distributed systems\\nYear: 2001\\n\\nAbstract: In the past few years we have developed an experimental distributed system that supports multi-task applications with different levels of criticality. Software implemented fault-tolerant protocols are used to support dependable computing. This paper first presents Markov models of a distributed system under the occurrence of faults, reconfiguration and repair. As a part of our overall project, these models are intended for solving our particular problems, like assessing the merits of redundant schemes, task allocation and reallocation policies, and fault handling used in our experimental system. However, these models are developed in a generic way. They can also be used in evaluating individual task's reliability, risk and availability under various redundant schemes in any homogeneous distributed system. Then, we extend our study in analysing the dependability of the heterogeneous system consisting of a number homogeneous distributed systems connected through gateways\",\n \"Title: Fast Detection of Path Failures in an Autonomous Decentralized System\\nYear: 2011\\n\\nAbstract: An autonomous decentralized system and a series of methods for reducing the detection time of path failures in the system are developed. Computing devices in the proposed system are organized into at least three groups based on their connectivity of system’s graph model. Each computing device is assigned three identification values associated with their group memberships. The identification values are stored in a router connected to the communications network. Heartbeat packets are sent from the computing devices to the router periodically. If the router fails to receive a heartbeat packet from a computing device, a failed communication path from the router to the computing device is determined based on the three identification values.\",\n \"Title: Design and Performance Evaluation of a Service-Oriented Robotics Application\\nYear: 2009\\n\\nAbstract: Service-oriented computing (SOC) is becoming increasingly important and is being adopted by more and more organizations. However, the applications and research of SOC have been limited to Web services and enterprise systems. Embedded systems and robotics applications are recent domains that SOC has been applied to. This paper provides an insight about the application of SOC for robotics, event-driven paradigm of designing robotics system, and a model for publishing and utilizing the artifacts that are required for building SOC-based robotics applications. The main benefit of SOC robotics application is to have a layer of common services with standard interfaces. The invocations of the services are device-independent. In this way, we can deploy the same application to different robotics platforms, as long as we rebind the service invocation to the services that are built for the robotics platform. Sponsored by Intel, we have developed a number of prototypes using different boards, processors, and drive systems. We have measured the performance and power consumption of these prototypes.\",\n \"Title: Service Replication Strategies with MapReduce in Clouds\\nYear: 2011\\n\\nAbstract: The current implementations of cloud environment do not have suitable mechanism through which services can be managed to make use of cloud resources. The services in these environments can passively serve users' request only. If a service receives more requests than it can handle in a certain time period, it is subject to malfunctioning. This paper proposes a new approach to service replications that allows a cloud to adjust its service instance deployments in response to existing and projected service request loads. This approach defines an optimal service replication strategy based on MapReduce, a processing model used extensively in GAE (Google App Engine) to solve huge data processing tasks. This service replication strategy is implemented by Service Level MapReduce (SLMR). To better support for SLMR, service replication technology is introduced, which include dynamic service replication and pre-deployed service replication. Furthermore, a passive SLMR approach that depends on the cloud management service (CMS) and a positive SLMR approach that does not need the support from CMS will be introduced.\",\n \"Title: Development of a Decentralized Virtual Service Redirector for Internet Applications\\nYear: 1999\\n\\nAbstract: An ongoing project of the Highly Dependable Systems Research Program (PHDS) at the University of the Witwatersrand is the development of a dependable distributed system and its application in supporting Internet services. The current research related to this project includes the design, specification, verification and implementation of a virtual service redirector for critical internet applications. This paper summarizes this system and related projects.\",\n \"Title: Ontology-Based Dependency-Guided Service Composition For User-Centric Soa\\nYear: 2010\\n\\nAbstract: Service-Oriented Architecture (SOA) is characterized by dynamic service discovery and composition. For user-centric SOA, not only services, but workflows and application templates also can be published and discovered for composition. This paper proposes a two-steps composition process, ontology-based dependency-guided service composition (OBDG). In the first step, users compose their templates based on domain ontology or using existing templates. In the second step, users submit the templates to the OBDG system and let the system complete the dependencies by choosing and finalizing the selection of services and workflows from a set of candidate services or workflows based on user preferences. In this paper, services are described as interface service and implementation service. Interface service is like a service specification that describes service interface and its description, which is used to build domain ontology. Implementation services implement interface services. OBDG maintains a one-to-many relationship between them plus test scripts and cases. Templates are composed by interface services or test script so they can be instantiated by implementation services or test scripts and cases. In this way, application templates and testing templates can be same, which means OBDG can instantiate same template as application or testing by choosing implementation service or test script.\",\n \"Title: Automatic Mutation Testing and Simulation on OWL-S Specified Web Services\\nYear: 2008\\n\\nAbstract: Web Ontology Language for Services (OWL-S) is a standard XML-based language for specifying workflows and integration semantics among Web services (WS), which form composite WS. This paper analyzes the fault patterns of OWL-S specified composite WS and their workflows, proposes an ontology-based mutation analysis method, and applies specification-based mutation techniques for composite WS simulation and testing. Four categories of OWL-S mutant operators are specified, including data mutation, condition mutation, control flow mutation, and data flow mutation. Finally, the paper studies the ontology-based input mutation technique using a BookFinder service as a case study, which shows that ontology-based mutation provides viable test adequacy criteria for testing OWL-S specified composite WS.\",\n \"Title: SOA Collaboration Modeling, Analysis, and Simulation in PSML-C\\nYear: 2006\\n\\nAbstract: This paper extends the ebXML Web services development framework to introduce a new collaboration framework, which is based on the collaboration specification language PSML-C (Process Specification and Modeling Language for Collaboration), CCSOA (Consumer-Centric Service-Oriented Architecture), and DDSOS (Dynamic Distributed Service-Oriented Simulation) framework. Since collaborations are inevitable and play a critical role in SOA, an effective framework will greatly reduce the effort for rapid and adaptive service composition, simulation, evaluation, and collaboration. The PSML-C collaboration framework provides a service-oriented infrastructure for process collaboration specification, modeling, design, code generation, simulation, deployment, execution, and management. This paper presents the concepts, architecture, enabling techniques, and illustrative examples that demonstrate the concepts and the techniques\",\n \"Title: Perspectives on Service-Oriented Computing and Service-Oriented System Engineering\\nYear: 2006\\n\\nAbstract: The Service-Oriented Computing (SOC) paradigm leads the innovation of today's computing system and software development, and it can transform the human society into a new republic of all-to-all connected world. There are a number of interesting and innovative research challenges involved in achieving this vision of Service-Oriented System Engineering (SOSE). This paper highlights some of these significant research opportunities and also the need for enhanced education in this emerging area.\",\n \"Title: Modeling and Simulation of Virtualized Autonomic Service Centers\\nYear: 2008\\n\\nAbstract: Large service centers are becoming widely used to host many different services on a shared computing infrastructure, for which autonomic control and management are necessary to meet the service quality targets and maximize the overall profit. This paper presents the architecture, design and implementation of a framework for modeling and simulating virtualized autonomic service centers. This provides methods of estimating the system behavior for capacity planning before real establishment or execution. In addition, the performance of an existing service center can be efficiently evaluated. Performance analysis shows that our system is moderately efficient to perform large-scale simulation. Moreover, detailed evaluation results also depict various aspects of the feasibility and the efficiency of our modeling and simulation approaches, which can help to improve the productivity of researchers via quick proof of concepts.\",\n \"Title: SOAVM: A Service-Oriented Virtualization Management System with Automated Configuration\\nYear: 2008\\n\\nAbstract: Virtualization technologies are becoming more and more widely used in the distributed computing area. In order to organize and manage various virtual machines in the SOA (Service Oriented Architecture) environment more effectively, a virtualization management system called SOAVM is proposed and demonstrated in this paper. SOAVM addresses the limitation of virtual appliances in software quantities by employing ACS (Automated Configuration Service). ACS provides a more flexible way to conduct automated software configuration on virtual machines compared to the traditional virtual appliance pattern. The system framework is designed, which defines all functions of SOAVM as services to comply with SOA. Then the system design is described, illustrating how ACS works. Furthermore, critical implementation issues are discussed in detail, which demonstrates that SOAVM is a feasible and efficient virtualization management system.\",\n \"Title: Dynamic system reconfiguration via service composition for dependable computing\\nYear: 2005\\n\\nAbstract: Dependable service-oriented computing is challenging because it faces an open, heterogeneous, and dynamic computing environment. In a service-oriented computing system, services developed by different vendors ondifferent platforms and in different programming languages perform computations collaboratively through open standard protocols. This paper presents an innovative dynamic reconfiguration technology that can be embedded into a service-oriented application tomake the application reconfigurable. Traditional reconfiguration algorithmassumes each component can independently switch without collaboration. The proposed reconfiguration agents are embedded in different services, and they communicate via a collaborative reconfiguration protocol to achieve a consistent reconfiguration decision. In addition, the reconfiguration protocol itself is fault-tolerant.\",\n \"Title: Internet of intelligent things and robot as a service.\\nYear: 2013\\n\\nAbstract: The development of computing and communication systems has gone through a spiral cycle of centralization and decentralization paradigms. The earliest computer systems are centralized mainframe computers. The paradigm moved to decentralized as networked stations became more dependable, extensible and cost-effective. The decentralized systems have their limitations and inconveniences. The virtualization and cloud computing paradigm creates a centralized system that appears to users to be a centralized system, where computing and communication resources are not in the client computers but in an integrated infrastructure that is accessible anywhere and anytime. Nevertheless, the implementation of the centralized infrastructure is equipped with decentralized and redundant resources, which makes the system more dependable as any component failures can be tolerated internally. The Internet of Things extends the cloud computing concept beyond computing and communication to include everything, particularly, the physical devices. This paper discusses the architectures, interfaces, and behaviors of intelligent devices connected to the cloud computing environment. Robot as a Service is the case study, which has all the key features of Internet of Intelligent Things: autonomous, mobile, sensing, and action taking. The goal is to further extend the centralized cloud computing environment into a decentralized system to complete another cycle of the spiral development. The idea of achieving the goal is through autonomous and intelligent mobile physical services or robots as services to form local pool of intelligent devices and that can make local decisions without communicate with the cloud.\",\n \"Title: Data provenance in SOA: security, reliability, and integrity.\\nYear: 2007\\n\\nAbstract: Due to the dynamic nature, such as services composition and evaluation, it is critical for a Service- Oriented Architecture (SOA) system to consider its data prov- enance, which concerns security, reliability, and integrity of data as they are being routed in the system. In a traditional software system, one focuses on the software itself to deter- mine the security, reliability, and integrity of the software. In an SOA system, however, one also needs to consider ori- gins and routes of data and their impact, i.e., data provenance. This paper first analyzes the unique nature and characteristics of data provenance in an SOA system, particularly related to data security, reliability, and integrity. Then it proposes a new framework for data provenance analysis in an SOA system. Finally, this paper uses an example which illustrates these techniques.\",\n \"Title: Service-oriented system engineering (SOSE) and its applications to embedded system development\\nYear: 2007\\n\\nAbstract: In the past few years, we witnessed a rapid progress in service-oriented computing (SOC), which represents a new computing\\n paradigm. SOC changes the way we develop and use software and hardware. Major enabling techniques, including service-oriented\\n architecture (SOA), service-oriented enterprise (SOE), service-oriented infrastructure (SOI), Web services (WS), and associated\\n protocols and standards are being established. This paper focuses on the system engineering issues and how these engineering\\n issues manifested in SOA development processes. SOSE differs from traditional system engineering because it emphasizes on\\n reusability, dynamic and adaptive nature, and unique model-driven approach.\",\n \"Title: Choosing cost-effective configuration in cloud storage.\\nYear: 2013\\n\\nAbstract: Cloud storage provides a virtually unlimited storage spaces for customers. Customers can combine their data storages from different types of cloud storage following their own requirements. End customers often stuck in choosing desirable configuration from different types of cloud storage. How to spend the minimum costs on using the highly efficient cloud storage? How to balance the relationship between the expenditures and performance? This paper proposes a cost-effective optimal configuration model using the repeated game model that can provide optimal configuration solutions to customers. The data mining techniques are used in provisioning on cloud storage. Classification helps users to find the related data and trend analysis assists users to mine the future trend on data storage. A simulate experiment is discussed and verify the correctness of the proposed model.\",\n \"Title: Collaboration Policy Generation in Dynamic Collaborative SOA\\nYear: 2007\\n\\nAbstract: Governance by policies is an important feature in Service-Oriented Architecture (SOA). This paper introduces a collaboration policy generation technique to govern dynamic collaboration in SOA systems. Dynamic collaboration allows two parties not knowing each other establish their collaboration protocol at runtime. Traditional SOA allows parties to collaborate but with a known collaboration protocol before execution. In dynamic collaboration, as collaboration protocols will be negotiated and determined at runtime, policies need to be generated at runtime to manage the interaction. This paper presents the concepts, architecture, and illustrative examples that demonstrate the dynamic collaboration policy generation technique.\",\n \"Title: Binary analysis and automated hot patching for Web-based applications\\nYear: 2006\\n\\nAbstract: Patching technologies are commonly applied to improve the dependability of software after release. This paper reports the design of an automated hot patching (AHP) framework that fully automates reasoning for the causes of failures and patching the binary code of Web-based applications. AHP admits the hardness for rooting out all faults before product release, and autonomously patches problems of application programs. By directly operating on binary code, AHP is universal to virtually all applications. A promising application of AHP is to shortcut a function of the remote maintenance center (RMC) and hence to reduce the turn around time for patches.\",\n \"Title: Simulating highly dependable applications in a distributed computing environment\\nYear: 2003\\n\\nAbstract: The aims of the research are to investigate techniques that support the development of highly dependable applications in a distributed system environment. Techniques we developed include redundant task allocation, load balancing, fault-tolerant computing and communication. The application we have implemented in the system is a firewall application. The firewall runs in redundant mode. Each incoming or outgoing packet is checked by two or more copies of the firewall application. Only when the majority of the firewall copies decide to accept the packet, the packet can go through the firewall. Different decisions from the different firewall copies signify a possible hardware fault or a software error in the underlying system. This paper reports a recent implementation of a simulation system, in which computing nodes, redundant copies of tasks and packet queues are implemented as independent threads, as well as experimental result we obtained based on queuing models.\",\n \"Title: On Robotics Applications in Service-Oriented Architecture\\nYear: 2008\\n\\nAbstract: Service-Oriented Computing (SOC) research and applications have been largely limited to software development in electronic and Web based applications. Service-oriented robotics software development extends SOC from its current fields to a new domain, which was considered not feasible because of the efficiency issues in terms of computing and communication. This paper presents the concepts, principles, and methods in SOC and SOC-based robotics software development and applies them in the design of distributed robotics applications. Two case studies, Intel security robot design and a maze-traversing robot application in Microsoft Robotics Studio, are used to illustrate the concepts and methods.\",\n \"Title: The Triangular Pyramid Scheduling Model and algorithm for PDES in Grid\\nYear: 2009\\n\\nAbstract: Grid is a perfect environment for the large scale Parallel Discrete Event Simulation (PDES), because its distribution and collaboration features match the PDES applications well. The PDES tasks or applications are modeled as a Directed Acyclic Graph (DAG), in which the simulation resources consist of three critical factors, simulation hosting machine (SHM), simulation service (SS) and simulation data (SD) in Grid environment. By solving the model we attempt to obtain an optimized triangular matching of the simulation resources on Grid, so that it can support the PDES activities better. We name the algorithm of solving the model Triangular Pyramid Scheduling (TPS). The PDES DAG is divided into three basic graph structures: Sequential structure, Fork structure, and Join structure. The TPS algorithm is developed based on these graph structures. The simulation results show that TPS algorithm can reduce the makespan and congestion, improve the simulation efficiency, and increase the resource utilization efficiency, compared to the existing algorithms.\",\n \"Title: V3COCA: An effective clustering algorithm for complicated objects and its application in breast cancer research and diagnosis\\nYear: 2009\\n\\nAbstract: In breast cancer studies, researchers often use clustering algorithms to investigate similarity/dissimilarity among different cancer cases. The clustering algorithm design becomes a key factor to provide intrinsic disease information. However, the traditional algorithms do not meet the latest multiple requirements simultaneously for breast cancer objects. The Variable parameters, Variable densities, Variable weights, and Complicated Objects Clustering Algorithm (V3COCA) presented in this paper can handle these problems very well. The V3COCA (1) enables alternative inputs of none or a series of objects for disease research and computer aided diagnosis; (2) proposes an automatic parameter calculation strategy to create clusters with different densities; (3) enables noises recognition, and generates arbitrary shaped clusters; and (4) defines a flexibly weighted distance for measuring the dissimilarity between two complicated medical objects, which emphasizes certain medically concerned issues in the objects. The experimental results with 10,000 patient cases from SEER database show that V3COCA can not only meet the various requirements of complicated objects clustering, but also be as efficient as the traditional clustering algorithms.\",\n \"Title: Service-Oriented User Interface Modeling and Composition\\nYear: 2008\\n\\nAbstract: Traditional service-oriented applications mainly focus on machine-to-machine interaction. However, human-machine interaction in applications also plays an important role. A better user interface can provide better usability and make the system user friendly. A user can be considered a service provider, where the user interaction is a workflow as a part of the system workflow and a user can place SOA User Interface (SOAUI) design into an overall system design. Traditionally, user interface design follows the MVC (Mode-View-Controller) architectural pattern. The SOAUI is a complement to the existing solution by providing the view for the application to the end-user.\",\n \"Title: An adaptive model-free resource and power management approach for multi-tier cloud environments\\nYear: 2012\\n\\nAbstract: With the development of cloud environments serving as a unified infrastructure, the resource management and energy consumption issues become more important in the operations of such systems. In this paper, we investigate adaptive model-free approaches for resource allocation and energy management under time-varying workloads and heterogeneous multi-tier applications. Specifically, we make use of measurable metrics, including throughput, rejection amount, queuing state, and so on, to design resource adjustment schemes and to make control decisions adaptively. The ultimate objective is to guarantee the summarized revenue of the resource provider while saving energy and operational costs. To validate the effectiveness, performance evaluation experiments are performed in a simulated environment, with realistic workloads considered. Results show that with the combination of long-term adaptation and short-term adaptation, the fluctuation of unpredictable workloads can be captured, and thus the total revenue can be preserved while balancing the power consumption as needed. Furthermore, the proposed approach can achieve better effect and efficiency than the model-based approaches in dealing with real-world workloads.\",\n \"Title: A Hierarchical Reliability Model of Service-Based Software System\\nYear: 2009\\n\\nAbstract: Service-Oriented Architecture (SOA) introduces a new paradigm where data, service, and the service composition logic are decoupled in an open environment. Software systems are built and evolved online by dynamic discovering and binding to the open services accessible through standard protocols. It requires new reliability modeling techniques to facilitate the analysis of dynamic collaborations and to be adaptable to the changes of service composition and system configuration at runtime. The paper proposes a hierarchical reliability model, in which the system reliability is calculated according to the layered superimposition of the reliabilities of data, services, fault-tolerant mechanism and service composition logic. At the basic-service layer, the service reliability is considered in the context of data reliability and service pools with backup alternatives. At the composition layer, a DTMC (Discrete Time Markov Chain) model is created for analyzing system reliability based on the reliability of the constituent services and their execution rate which are decided by the composite control structure and the operation scenarios. The DTMC state transition diagram can be automatically generated by analyzing and transforming the layered superimposition of the application following the transformation rules. The hierarchical modeling framework enables change adaptation at various levels. In addition, the models can be continuously learned and dynamically adjusted by profiling on the runtime monitoring log files.\",\n \"Title: A Coverage Relationship Model for Test Case Selection and Ranking for Multi-version Software\\nYear: 2007\\n\\nAbstract: Testing a group of software artifacts that implement the same specification can be time consuming, especially when the test case repository is large. In the meantime, some test cases may cover the same aspects in the software, thus it is not necessary to apply all the test cases. This paper proposes a Model-based Adaptive Test (MAT) case selection and ranking technique to eliminate duplicate test cases, i.e., test cases with the similar coverage, and rank the test cases according to their potency and coverage. This technique can be applied in various domains where multiple versions of applications are available to test, such as web service testing, n-version applications, regression testing, and standard-based testing. The MAT is based a statistical model based on earlier testing results, and the model can determine the next sets of test cases to minimize the testing effort. The MAT is then applied to testing of multi-versioned web services and the results shows that the MAT can reduce testing effort while still maintain the effectiveness of testing.\",\n \"Title: Structure-oriented dependability evaluation of fault-tolerant protocols\\nYear: 1994\\n\\nAbstract: Fault-tolerant protocols are special software components used to maintain correct communication and computing in highly dependable distributed systems. Before being put into use, the correctness or dependability of a fault-tolerant protocol must be ensured. Based on a deterministic test strategy with imperfect error correction, we propose and investigate a quantified reliability model for fault-tolerant protocols. The parameters of the model can be estimated from the frequencies of the failures attributable to a single design error and from the times between the failures attributable to different design errors observed during testing.\",\n \"Title: Virtualization-based autonomic resource management for multi-tier Web applications in shared data center\\nYear: 2008\\n\\nAbstract: As large data centers emerge, which host multiple Web applications, it is critical to isolate different application environments for security reasons and to provision shared resources effectively and efficiently to meet different service quality targets at minimum operational cost. To address this problem, we developed a novel architecture of resource management framework for multi-tier applications based on virtualization mechanisms. Key techniques presented in this paper include (1) establishment of the analytic performance model which employs probabilistic analysis and overload management to deal with non-equilibrium states; (2) a general formulation of the resource management problem which can be solved by incorporating both deterministic and stochastic optimizing algorithms; (3) deployment of virtual servers to partition resource at a much finer level; and (4) investigation of the impact of the failure rate to examine the effect of application isolation. Simulation experiments comparing three resource allocation schemes demonstrate the advantage of our dynamic approach in providing differentiated service qualities, preserving QoS levels in failure scenarios and also improving the overall performance while reducing the resource usage cost.\",\n \"Title: Composing Highly Reliable Service-Oriented Applications Adaptively\\nYear: 2008\\n\\nAbstract: This paper proposes dynamic and adaptive reliability methods that can be integrated into a collaborative composition framework with dynamic verification and adaptive reliability modeling. The composition process follows a template-based approach with ontology systems where a variety of items can be reused including services, workflows, application templates, and test cases/scripts. Items submitted to publication are subjected to test and evaluation before they can be published and reused. Test cases can also be ranked based on their effectiveness and test cases will be continuously re-ranked based on recent testing results and reliability modeling. Composed applications will be tested and evaluated before deployment, and even during execution, applications will be monitored so that their reliability can be continuously updated. This paper proposed several adaptive mechanisms to estimate software reliability and update test case effectiveness. They are illustrated by examples.\",\n \"Title: Robot as a Service in Cloud Computing\\nYear: 2010\\n\\nAbstract: Service-oriented architecture and cloud computing are becoming a dominant computing paradigm, as all major computing companies are supporting this paradigm and more and more organizations are adopting this paradigm. Robotics and service-oriented robotics computing start to joint this new paradigm in the past five years and are now ready to participate in large scale. This paper reports our research on service-oriented robotics computing and our design, implementation, and evaluation of Robot as a Service (RaaS) unit. To fully qualify the RaaS as a cloud computing unit, we have kept our design to comply with the common service standards, development platforms, and execution infrastructure. We also keep the source code open and allow the community to configure the RaaS following the Web 2.0 principles of participation. Developers can add, remove, and modify the RaaS of their own. For this purpose, we have implemented our RaaS on Windows and Linux operating systems running on Atom and Core 2 Duo architectures. RaaS supports programming languages commonly used for service-oriented computing such as Java and C#. Special efforts have been made to support Microsoft Visual Programming Language (VPL) for graphic composition. We are working with high schools to use RaaS and VPL in robotics camps and robotics competitions.\",\n \"Title: Design of a Robot Cloud Center\\nYear: 2011\\n\\nAbstract: Service-oriented architecture and cloud computing have become the prevalent computing paradigm. In this paradigm, computing resources can be accessed like other utility services available in today's society. In the meantime, robotics applications are joining the trend. More and more robot applications are shifting from manufacture to non-manufacture and service industries. However, for the on-demand supply of the large-scale heterogeneous robots, It is still a problem have not yet been studied, including the fundamental management and efficiency issues in using of these resources. In this paper, we design a framework of \\\"Robot Cloud Center\\\" (RCC) following the general cloud computing paradigm to address the current limitations in capacity and versatility of robotic applications. In this framework, a robot can be provided as a service just like a public utility service so that everyone can access the powerful robotic services easily, efficiently, and cheaply. Based on a given scenario, a robot scheduling algorithm in RCC is proposed to take advantage of the heterogeneous robot resources to meet the end user's requirement with the minimum cost.\",\n \"Title: A content and user-oblivious video-recommendation algorithm\\nYear: 2011\\n\\nAbstract: Videos have become popular on Internet, and corresponding video-recommendation algorithms have become an important factor for maintaining user’s satisfactory level and the profits of video-service providers. Existing recommendation algorithms are often highly dependent on the precious information of contents and users. However in many scenarios those information is not available for privacy reasons. This paper provides a watching sequence-based video-recommendation algorithm that can work well without the video contents and users information. The algorithm consists of three models: the exactly prefix matching tree, partial prefix matching tree, and the postfix matching tree. The final recommendation results are composed from the three models. The corresponding search tree, the matching search tree, and weight calculating algorithm are developed for each model. The algorithm is evaluated based on the half-year log files of a practical video website. The experimental results show that our algorithm performs better on execution time, accuracy, diversity of recommendation results, and non-hot coverage than the traditional recommendation algorithms.\",\n \"Title: Autonomous hot patching for Web-based applications\\nYear: 2005\\n\\nAbstract: Patching technologies are commonly applied to improve the dependability of software after release. This paper proposes an autonomous hot patching (AHP) framework to fully automate the reasoning for the causes of failures, and to patch the binary code of Web-based applications. AHP admits the hardness for rooting out all faults before product release, and autonomously patches problems of application programs. By directly operating on binary code, AHP is universal to virtually all applications. A promising application of AHP is to shortcut the remote maintenance center (RMC) and hence to reduce the turn around time for patches.\",\n \"Title: An Introductory Course On Service-Oriented Computing For High Schools\\nYear: 2008\\n\\nAbstract: Service-Oriented Computing (SOC) is a new computing paradigm that has been adopted by major computer companies as well as government agencies such as the Department of Defense for mission-critical applications. SOC is being used for developing Web and electronic business applications, as well as robotics, gaming, and scientific applications. Yet, SOC education is lagging. In spite of significant progresses in SOC technology and applications, SOC education has not been taught in introductory classes, even if it is technologically feasible. Most of the existing SOC courses are either graduate seminars or senior-level courses at various universities. On the other hand, SOC is component-based and introduces a high-level of abstraction, which makes it possible to teach computing within an application domain, such as robotics. In other words, the SOC learning process focuses more on the application logic rather than the syntax of programming languages, potentially making computer education entertaining. The Computer Science & Engineering Department and the College of Education at Arizona State University, in cooperation with the Scottsdale Unified School District and Coronado High School, pioneered the first SOC course for high schools (grades 9 through 12) in the Spring and Fall of 2007. The course was also offered in summers 2006, 2007, and 2008 to high school students and teachers. This course is designed so that even high school students without any computing training can learn the latest software technologies in an entertaining manner. Specifically, this course uses a visual programming environment so students can design their software visually. Thus, they can learn control constructs but do not need to focus on the details of programming language syntax. Furthermore, once the software is designed, a visual 3-D simulator can give students instantaneous feedback. Finally, the software designed can be downloaded into LEGO robots for robotic competition. Most students who took the course rated the course \\\"very well\\\" or \\\"pretty well\\\" and some indicated that they are interested enough to contemplate pursuing computer science as their career.\",\n \"Title: Autonomous decentralised systems in web computing environment\\nYear: 2011\\n\\nAbstract: This introductory note outlines autonomous decentralised systems (ADS) technologies as applied to service-oriented computing (SOC) and cloud computing environments, and also introduces the papers in the special issue.\",\n \"Title: Mutation-Based Simulation Test Data Generation for Testing Complex Real-Time Software\\nYear: 2007\\n\\nAbstract: Simulation is proven to be an effective way for testing complex real-time hardware/software systems. However, simulation test data generation is a challenging issue which determines the efficiency in such testing. This paper proposed a data-driven mutation based approach for test data generation to address the unique requirements of real-time, input domain coverage, adaptability, and reliability. The architecture is designed to simulate the process for data sampling, transforming, packaging, and transmitting segments in an aerospace ground control system. Various mutant operators are defined for signal generation and data package generation to produce fault-sensitive inputs based on the system's fault pattern analysis. Mechanisms are defined to generate a large number of test cases by combination and composition of various data outputs from different dimensions to achieve a high coverage. A configuration mechanism is introduced to enable recomposition and re-combination of simulation components. The selective simulation testing method is discussed to improve test effectiveness. A case study shows that the proposed approach can achieve a high fault-coverage with a small number of effective test cases.\",\n \"Title: Roadmap to a Full Service Broker in Service-Oriented Architecture\\nYear: 2007\\n\\nAbstract: Service-broker is an important mechanism in Service-Oriented Architecture (SOA), which facilitates service registration, publication, and discovery. UDDI and ebXML are two major standards that implement service brokerage by providing service registry and service repository. As SOA applications become pervasive, the need for more powerful service broker becomes a necessity. This paper explores the features, criteria of the future service brokers that can meet the increasing needs in SOA software development.\",\n \"Title: Service-orientation in computing curriculum\\nYear: 2011\\n\\nAbstract: Web software development and cloud computing based on Service-Oriented Architecture (SOA) and Service-Oriented Computing (SOC) represent the modern software engineering theories, practices, and technologies. As an architecture-driven computing paradigm, SOA and SOC are mature and are becoming the major paradigm for software development. SOA and SOC should be taught in all computer science and computer engineering programs. We do not suggest using SOC to replace the currently taught Object-Oriented Computing (OOC) paradigm. As SOC is based on OOC, we suggest to teaching SOC as the continuation and extension of OOC. At Arizona State University, SOA and SOC paradigm is incorporated into our Computing Science and Software Engineering programs since 2006. This paper presents the topics of the related courses and the open resources created for the courses, which are available for public accesses, including textbooks, lecture presentation slides, tests and assignments, software tools, a repository of sample services and applications, and tutorials of using tools and the cloud computing environment for service hosting and deployment.\",\n \"Title: An Infrastructure for Web Services Migration for Real-Time Applications\\nYear: 2006\\n\\nAbstract: Service-oriented architecture (SOA) is a highly promising technology for software development. It can greatly reduce the development time and cost and achieve system agility. Web service is the current practice for realizing SOA. Due to the nature of widely distributed Web service providers, the service performance could be impacted when the network traffic is congested. There are methods, such as communication cost based service selection strategies, developed to cope with the problem. In this paper, we propose a complementing technology, migratable Web services, to overcome the performance problems for real-time applications. A service can be implemented by multiple light weighted Web services and some of them can be migrated to strategic sites to minimize the communication delays so the real-time requirements can be met. We have designed an infrastructure to support Web service migration and execution. Also, appropriate decision mechanism, which decides whether a Web service should be migrated and where to send it to, is the key for major performance gains. We use genetic algorithm to efficiently make the best migration decisions. Experimental studies show that the approach can achieve significant performance improvement\",\n \"Title: Assuring Mobile Physical Services for the New Generation of Networks\\nYear: 2011\\n\\nAbstract: The development of computing and communication systems has gone through a spiral cycle of centralization and decentralization schemas. The earliest telephone network used decentralized point-to-point connections. It moved to centralized switching system as the number of devices increased. The centralized computing and communication systems further moved into a decentralized paradigm, as devices expand and dependability of large systems becomes a dominating factor. The current cloud computing and communication systems appear to be a centralized system where computing and communication resources are not in the client computers but in an integrated infrastructure. Nevertheless, the implementation of the centralized infrastructure is equipped with decentralized and redundant resources, which makes the system more dependable as any internal failures can be tolerated internally. However, the terminal devices and their interfaces to the centralized infrastructure remain vulnerable to the single-point-of-failures. This paper focuses on terminal devices and their interfaces to the new generation of assurance network and presents the challenges of making the devices and the interfaces as dependable as the assurance network. The idea of achieving the goal is through a pool of Mobile Physical Services (MPS) that can connect to multiple networks and can be shared by neighboring users.\",\n \"Title: UCSOA: User-Centric Service-Oriented Architecture\\nYear: 2006\\n\\nAbstract: This paper introduces a new user-centric serviceoriented architecture (UCSOA) that allows end users to compose applications. UCSOA is an extension of consumer-centric service-oriented architecture CCSOA), which is an extension of conventional SOA. The conventional SOA is producer-centric because service providers publish their services and service consumers must search available services to compose their applications. CCSOA is different as it allows consumers publish their needs including workflows and services, and let producers to produce services to meet the requirements. Based on CCSOA, UCSOA provides support for end users. An application builder is an engineer who has both domain and programming knowledge, while an end user has little knowledge on programming and thus UCSOA needs to allow nontechnical persons to compose their applications. This paper presents the concepts, architecture, enabling techniques, and illustrative examples.\",\n \"Title: A service-oriented modeling and simulation framework for rapid development of distributed applications\\nYear: 2006\\n\\nAbstract: The paper presents a service-oriented distributed modeling and simulation framework that supports the development and evaluation of large scale distributed systems such as network-centric and system-of-systems applications. The distinct features of the framework include a modeling and specification language, dynamic model checking for completeness and consistency, automated code generation from the specification, simulation of different architectures with a template-based platform builder, service-oriented multi-agent simulation for easy re-configuration and re-composition, formal policy specification and enforcement for dynamic verification, and dynamic analyses for evaluation and monitoring. The framework and most of the tools reported in this paper have been implemented and applied in several industrial projects. This paper presents the design principles, user interfaces, its runtime infrastructure, and the experiment results on its performance.\",\n \"Title: A Machine Learning-Based Reliability Assessment Model for Critical Software Systems\\nYear: 2007\\n\\nAbstract: Service-oriented architecture (SOA) techniques are being increasingly used for developing critical applications, especially network-centric systems. While the SOA paradigm provides flexibility and agility to better respond to changing business requirements, the task of assessing the reliability of SOA-based systems is challenging, especially for composite services. However, deriving high confidence reliability estimates for missioncritical systems can require huge costs and time. This paper presents a reliability assessment and prediction model for SOA-based systems. The services are assumed to be realized with reuse and logical composition of components. The model uses AI reasoning techniques on dynamically collected failure data of each service and its components as one of the evidences together with results from random testing. Memory-Based Reasoning technique and Bayesian Belief Networks are used as reasoning tools to guide the prediction analysis. The least tested and \\\"high usage\\\" input subdomains are identified and necessary remedial actions are taken depending on the predicted results from the proposed model. The model is illustrated using a simulated case study based on a real-time dataset from the NASA software repository.\",\n \"Title: The Temporal Correlation Hypothesis For Self-Organizing Feature Maps\\nYear: 2000\\n\\nAbstract: Feature maps, in which one or more aspects of the environment are systematically represented over the surface of the cerebral cortex, are of ten found in primary sensory and motor cortical regions of the vertebrate brain. They have inspired a great deal of computational modelling, and this has provided evidence that such maps are emergent properties of the interactions of numerous cortical neurons and their adaptive, nonlinear connections. In this paper, we address the issue of how multiple feature maps that coexist in the same region of cerebral cortex align with each other. We hypothesize that such alignment is governed by temporal correlations : features in one map that are temporally correlated with those in another come to occupy the same spatial locations over time. To examine the feasibility of this hypothesis and to establish some of its detailed implications, we initially studied a computational model of primary sensorimotor cortex. Coexisting sensory and motor maps formed and generally aligned in a fashion consistent with the temporal correlation hypothesis. We summarize these results, and then mathematically analyse a simplified model of self-organization during unsupervised learning. We show that the properties observed computationally are quite general : that temporally correlated inputs become spatially correlated (i.e. aligned), while input patterns that are temporally anti-correlated tend to result in mutually exclusive (i.e. unaligned) spatial distributions. This work provides a framework in which to interpret and understand future experimental studies of map relationships.\",\n \"Title: A Cost-Effective Intelligent Configuration Model in Cloud Computing\\nYear: 2012\\n\\nAbstract: Cloud computing environments provide a resource pool for customers for their processing, storage and networking needs. It is necessary for customers to choose desirable configuration from vast resources available in the cloud. This paper proposes a heuristic model to choose a cloud configuration for efficient use. Trend analysis in data mining is used to predict the future trend and assist provisioning. The model is experimented with Intel power 32 core machine and in Azure cloud. Both environments demonstrated that the proposed model provided effective solutions.\",\n \"Title: Typical Virtual Appliances: An optimized mechanism for virtual appliances provisioning and management\\nYear: 2011\\n\\nAbstract: A computing infrastructure requirement in the cloud computing environment can be specified and composed using virtual appliances, which forms the infrastructure-as-a-service (IaaS). Due to the diversity of user requirements, a large number of virtual appliances may be needed. We propose a mechanism called Typical Virtual Appliances (TVAs), an efficient method for providing virtual appliances. In this paper, we present the concept of TVAs and formulate it as an optimization problem with given constraints. With analysis of the software download logs of real web sites, we discover that the number of user requirements follows a quadratic polynomial distribution, and the user requirements are clustered in nature. According to this finding, we develop a clustering-based TVAs generation algorithm, and we show that this algorithm can achieve the optimal result. The clustering algorithm can generate TVAs, which can be transformed to other virtual appliances easily and efficiently. We further design a TVA Management System (TVAMS) to support this mechanism. The simulation results show that our method can meet most of the user requirements efficiently with low storage overhead.\",\n \"Title: Virtual Workspace Based Job Execution Methods and Dynamic Makespan Optimized Scheduling Algorithms\\nYear: 2008\\n\\nAbstract: The virtualization technology is helpful to support grid QoS. A manual configuration method and an automatic configuration method are designed to build the virtual workspace environment based on virtualization technology. Both the MetaServices and the automatic configuration software are employed to establish the virtual workspace environment. For dynamic jobs, the corresponding Dynamic Makespan Optimized (DMO) scheduling algorithms are developed. Results of the simulation experiments demonstrate that, compared to models without virtualization support, the job execution methods and DMO scheduling algorithms proposed in this paper can achieve higher throughput, optimize job makespan, and improve the QoS of grid systems.\",\n \"Title: An Approach for Service Composition and Testing for Cloud Computing\\nYear: 2011\\n\\nAbstract: As cloud services proliferate, it becomes difficult to facilitate service composition and testing in clouds. In traditional service-oriented computing, service composition and testing are carried out independently. This paper proposes a new approach to manage services on the cloud so that it can facilitate service composition and testing. The paper uses service implementation selection to facilitate service composition similar to Google’s Guice and Spring tools, and apply the group testing technique to identify the oracle, and use the established oracle to perform continuous testing for new services or compositions. The paper extends the existing concept of template based service composition and focus on testing the same workflow of service composition. In addition, all these testing processes can be executed in parallel, and the paper illustrates how to apply service-level MapReduce technique to accelerate the testing process.\",\n \"Title: Dynamic Collaboration Simulation in Service-Oriented Computing Paradigm\\nYear: 2007\\n\\nAbstract: In Service-Oriented Architecture (SOA) and Service-Oriented Computing (SOC), service collaboration is an important aspect. While service collaboration protocols for data exchange are well explored, the Dynamic Process Collaboration (DPC) is still a challenging issue. The DPC brings new features and uncertainty to the current SOA/SOC, such as run-time behavior evaluation, dynamic collaboration performance measurement and dynamic Recomposition/ Reconfiguration capability assessment. This paper presents the Dynamic Service-Oriented Collaboration Simulation (DSOCS) framework we have developed, which supports the dynamic collaboration, development, simulation, and evaluation of large scale SOA systems. The distinct features of the framework include automated simulation code generation from the specification, code deployment, and simulation of different architectures with a template-based platform builder, service-oriented multi-agent simulation for easy reconfiguration, and dynamic analyses of results from evaluation and monitoring. The framework and the associated tools have been implemented and applied in several governmental and industrial projects.\",\n \"Title: Ontology-based Dynamic Process Collaboration in Service-Oriented Architecture\\nYear: 2007\\n\\nAbstract: Service collaboration is important in Service- Oriented Architecture (SOA). While service collaboration protocols for data exchange are well explored, the Dynamic Process Collaboration (DPC) is still a challenge. DPC requires not only exchanging meaningful information between collaboration parties, but also performing collaboration workflow matching based on collaboration ontology. To do this, DPC needs service collaboration ontology modeling, service collaboration discovery and establishment based on collaboration ontology and runtime recomposition capability. This paper presents an Ontology-based Dynamic Process Collaboration (ODPC) framework with these features to facilitate DPC.\",\n \"Title: A framework for contract-based collaborative verification and validation of web services\\nYear: 2007\\n\\nAbstract: A key issue with Web Services (WS) is the verification and validation (V&V) of services to build trust between service providers and service users. This paper proposed a test-broker architecture so that all stakeholder within WS can contribute to improve the testing of the services. The test broker supports the submission, indexing, and querying of test artifacts such as test cases, defect reports and evaluations. It can also provide the services for the test generation, test coordination, and distributed testing services. The DCV&V (Decentralized, Collaborative, Verification and Validation) framework is proposed with a set of distributed and collaborated test brokers dedicated to different V&V tasks to enable scalable and flexible test collaborations. The paper explores the concept of design-by-contract and applies the principle to DCV&V. It identifies two categories of testing contracts including TSC (Testing Service Contracts) and TCC (Test Collaboration Contracts). It illustrates the application of TSC with contract-based test generation based on WS OWL-S specification. It elaborates TCC with the analysis of the test artifacts definitions.\",\n \"Title: The Simulation of a Highly Dependable Distributed Computing Environment.\\nYear: 2003\\n\\nAbstract: The aim of the research is to investigate techniques that support the development of highly dependable applications in a distributed system environment. Techniques developed include redundant task allocation, load balancing, fault-tolerant computing, and communication. The application the authors have implemented in the system is a firewall application. The firewall runs in redundant mode. Each incoming or outgoing packet is checked by two or more copies of the firewall application. Only when the majority of the firewall copies decide to accept the packet can the packet go through the firewall. Disagreed decision from the different firewall copies signify a possible hardware fault or a software error in the underlying system. This article reports a recent implementation of a simulation system in which computing nodes, redundant copies of tasks, and packet queues are implemented as independent threads, as well as experiment results obtained based on queuing models.\",\n \"Title: Priori information and sliding window based prediction algorithm for energy-efficient storage systems in cloud.\\nYear: 2013\\n\\nAbstract: One of the major challenges in cloud computing and data centers is the energy conservation and emission reduction. Accurate prediction algorithms are essential for building energy efficient storage systems in cloud computing. In this paper, we first propose a Three-State Disk Model (3SDM), which can describe the service quality and energy consumption states of a storage system accurately. Based on this model, we develop a method for achieving energy conservation without losing quality by skewing the workload among the disks to transmit the disk states of a storage system. The efficiency of this method is highly dependent on the accuracy of the information predicting the blocks to be accessed and the blocks not be accessed in the near future. We develop a priori information and sliding window based prediction (PISWP) algorithm by taking advantage of the priori information about human behavior and selecting suitable size of sliding window. The PISWP method targets at streaming media applications, but we also check its efficiency on other two applications, news in webpage and new tool released. Disksim, an established storage system simulator, is applied in our experiments to verify the effect of our method for various users’ traces. The results show that this prediction method can bring a high degree energy saving for storage systems in cloud computing environment.\",\n \"Title: Services utility prediction on a cloud\\nYear: 2011\\n\\nAbstract: Cloud computing and Software-as-a-Service (SaaS) are being widely applied. In the near future, there will be many cloud services providing similar services. One of the issues is to dispatch service requests to available services dynamically so that service requests can be served in the most effective and efficient way. This paper proposes an algorithm that efficiently serves requests for services by predicting the number of services needed. Furthermore, a cloud architectural framework to support the algorithm and prediction model is introduced. The paper also presents a simulation study to validate the algorithm proposed.\",\n \"Title: Voting Multi-Dimensional Data with Deviations for Web Services under Group Testing\\nYear: 2005\\n\\nAbstract: Web Services (WS) need to be trustworthy to be used in critical applications. A technique called WS Group Testing has been proposed which can significantly reduce the cost of testing and ranking a large number of WS. A main feature of WS group testing is that it is able to establish the test oracles for the given test inputs from multiple WS and infer the oracles by plural voting. Efficient voting of complex and large number of data is critical to the success of group testing. Current voting techniques are not designed to deal with such a situation. This paper presents efficient voting algorithms that determine the plural value on multi-dimensional data and large number of data. The algorithm uses a clustering method to classify data into regions to identify the plural value. Experiments are designed and performed to concept-prove the algorithms and their applications with group testing.\",\n \"Title: DDSOS: A Dynamic Distributed Service-Oriented Simulation Framework1\\nYear: 2006\\n\\nAbstract: This paper presents the DDSOS framework developed at Arizona State University, which supports the simulation, development, and evaluation of large scale distributed systems such as network-centric and system-of-systems applications. The distinct features of the framework include automated simulation code generation from the specification, code deployment, simulation of different architectures with a templatebased platform builder, service-oriented multi-agent simulation for easy reconfiguration, and dynamic analyses of results from evaluation and monitoring. The framework and the associated tools have been implemented and applied in several governmental and industrial projects.\",\n \"Title: Swiss Cheese Test Case Generation for Web Services Testing\\nYear: 2005\\n\\nAbstract: Current Web services testing techniques are unable to assure the desired level of trustworthiness, which presents a barrier to WS applications in mission and business critical environments. This paper presents a framework that assures the trustworthiness of Web services. New assurance techniques are developed within the framework, including specification verification via completeness and consistency checking, test case generation, and automated Web services testing. Traditional test case generation methods only generate positive test cases that verify the functionality of software. The proposed Swiss Cheese test case generation method is designed to generate both positive and negative test cases that also reveal the vulnerability of Web services. This integrated development process is implemented in a case study. The experimental evaluation demonstrates the effectiveness of this approach. It also reveals that the Swiss Cheese negative testing detects even more faults than positive testing and thus significantly reduces the vulnerability of Web services.\",\n \"Title: Bounds on the reliability of distributed systems with unreliable nodes and links\\nYear: 2004\\n\\nAbstract: The reliability of distributed systems & computer networks in which computing nodes and/or communication links may fail with certain probabilities have been modeled by a probabilistic network. Computing the residual connectedness reliability (RCR) of probabilistic networks under the fault model with both node & link faults is very useful, but is an NP-hard problem. Up to now, there has been little...\",\n \"Title: Distributed collaborative filtering with singular ratings for large scale recommendation\\nYear: 2014\\n\\nAbstract: Collaborative filtering (CF) is an effective technique addressing the information overloading problem, where each user is associated with a set of rating scores on a set of items. For a chosen target user, conventional CF algorithms measure similarity between this user and other users by utilizing pairs of rating scores on common rated items, but discarding scores rated by one of them only. We call these comparative scores as dual ratings, while the non-comparative scores as singular ratings. Our experiments show that only about 10% ratings are dual ones that can be used for similarity evaluation, while the other 90% are singular ones. In this paper, we propose SingCF approach, which attempts to incorporate multiple singular ratings, in addition to dual ratings, to implement collaborative filtering, aiming at improving the recommendation accuracy. We first estimate the unrated scores for singular ratings and transform them into dual ones. Then we perform a CF process to discover neighborhood users and make predictions for each target user. Furthermore, we provide a MapReduce-based distributed framework on Hadoop for significant improvement in efficiency. Experiments in comparison with the state-of-the-art methods demonstrate the performance gains of our approaches.\",\n \"Title: Design and analysis on trusted network equipment access authentication protocol.\\nYear: 2015\\n\\nAbstract: Cloud security is a system engineering problem. A common approach to address the problem is to adapt existing Trusted Network Connection (TNC) framework in the cloud environment, which can be used to assess and verify end clients’ system state. However, TNC cannot be applied to network equipment attached to the cloud computing environment directly. To allow the network devices to access the trusted network devices safely and reliably, we first developed a Trusted Network Equipment Access Authentication Protocol (TNEAAP). We use the BAN logic system to prove that TNEAAP is secure and credible. We then configure the protocol in an attack detection mode to experimentally show that the protocol can withstand attacks in the real network. Experiment results show that all the nine goals that decide the protocol’s security have been achieved.\",\n \"Title: On monitoring and predicting mobile network traffic abnormality.\\nYear: 2015\\n\\nAbstract: Traffic analysis and traffic abnormality detection are emerged as an efficient way of detecting network attacks in recent years. The existing approaches can be improved by introducing a new model and a new analysis method of network user’s traffic behaviors. The description dimensions to network user’s traffic behaviors in the current approaches are high, resulting in high processing complexity, high delay in differentiating an individual user’s abnormal traffic behavior from massive network data, and low detection rate. To improve the detection rate and efficiency, we develop a new method of establishing user’s traffic behavior analysis system based on a new model of network traffic monitoring. First, we establish a more complete feature set based on the characteristics of network traffic to describe massive network user’s behaviors. Then, we define a feature selection rule based on the relative deviation distance to select the optimized feature set. We use the selected feature set to locate the abnormality moment and the users who produce the abnormal traffic behavior. Finally, a traffic behavior analysis method based on prediction is developed to improve efficiency of the system. This new method is applied to evaluate the mobile users on mobile cloud. The experimental results show that the proposed method has a higher detection rate and lower delay in the analysis of abnormal user’s traffic behavior than that of the existing approaches.\",\n \"Title: Service-Oriented Computing and Software Integration in Computing Curriculum\\nYear: 2014\\n\\nAbstract: Web software development and cloud computing based on Service-Oriented Architecture (SOA) represent the latest parallel distributed computing theories, practices, and technologies. As a distributed software development diagram, SOA is being taught in many computer science programs. We do not suggest using SOA to replace the currently taught Object-Oriented Computing paradigm. As SOA is based on Object-Oriented Computing, we suggest teaching SOA as the continuation and extension. At Arizona State University, SOA paradigm is incorporated into our Computing Science program since 2006. This paper presents the topics of the related courses and the open resources created for the courses, which are available for public accesses, including textbooks, lecture presentation slides, tests and assignments, software tools, and a repository of components, services and applications.\",\n \"Title: Trust-Based Security for the Spanning Tree Protocol\\nYear: 2014\\n\\nAbstract: Attacks executed on Spanning Tree Protocol (STP) expose the weakness of link layer protocols and put the higher layers in jeopardy. Although the problems have been studied for many years and various solutions have been proposed, many security issues remain. To enhance the security and credibility of layer-2 network, we propose a trust-based spanning tree protocol aiming at achieving a higher credibility of LAN switch with a simple and lightweight authentication mechanism. If correctly implemented in each trusted switch, the authentication of trust-based STP can guarantee the credibility of topology information that is announced to other switch in the LAN. To verify the enforcement of the trusted protocol, we present a new credible evaluation method of the STP using a specification-based state model. We implement a prototype of trust-based STP to investigate its practicality. Experiment shows that the trusted protocol can achieve security goals and effectively avoid STP attacks with a lower computation overhead and good convergence performance.\",\n \"Title: A Foot-Mounted Sensor Based 3D Indoor Positioning Approach\\nYear: 2015\\n\\nAbstract: We present a 3D indoor positioning system with foot mounted low cost MEMS sensors. The sensors includes the accelerometers, gyroscopes, and barometer. The output of accelerometers and gyroscopes are used to calculate the zero velocity update (ZUPT) and the movement of one step. The barometer is used to detect the altitude changes. A Kalman filter based framework is used to fusion the outputs of the sensors and estimate the non-linear errors of the position and heading, which increased over time. A particle filter is used to further reduce the errors. The test result shows that the designed system perform well.\",\n \"Title: Evaluation of deterministic fault injection for fault-tolerant protocol testing\\nYear: 1991\\n\\nAbstract: A deterministic test strategy consisting of deterministic fault injection at the message level is investigated. Messages sent by faulty units are replaced by such wrong messages that cause all program parts of the faultless protocol units to be executed subsequently. Since this well-aimed fault injection poses complex problems, heuristics based on the program flow of previous injections of wrong messages is dynamically applied. The program parts to be tested are selected with increasing granularity until either a design error is found or sufficient structural coverage is reached, which reflects the portion of tested program parts. Using a simplified program model, an algebraic analysis of the structural coverage and the design error coverage, which is the probability to reveal an existing design error, is carried out. It is shown that fault-tolerant protocol testing by deterministic fault injection achieve better coverages than by random fault injection.<>\",\n \"Title: Progressive ranking and composition of Web services using covering arrays\\nYear: 2005\\n\\nAbstract: Major computer companies and government agencies are adopting Web services (WS) technology. Web services must ensure interoperability and security, and be reliable and trustworthy. Consumers must make runtime decisions based on an intelligent and unbiased evaluation. We propose one component of a test suite generator to address this critical issue. The goal is to transform the labor-intensive software development process into a largely automated Web services development process. The method operates within a service-oriented architecture, with the models and tools implemented as services that can be added, removed and replaced at runtime. We propose a generic greedy algorithm based on covering arrays for application in this environment.\",\n \"Title: Specification-based verification and validation of Web services and service-oriented operating systems\\nYear: 2005\\n\\nAbstract: Service-oriented architecture (SOA) and Web services (WS) have received significant attention recently. Even though WS are based on open standards and support software interoperability, but the trustworthy issues of WS has actually limited the growth of WS applications as organizations do not trust those WS developed by other vendors and at the same time they do not have access to the source code. This paper addressed this issue by proposing several solutions including specification-based verification and validation, collaborative testing, and group testing. The key concept is that it is possible to provide a comprehensive evaluation of WS even if their source code is not available.\",\n \"Title: Stochastic voting algorithms for Web services group testing\\nYear: 2005\\n\\nAbstract: This paper proposes a stochastic voting for testing a large number of Web services (WS) under group testing. In the future, a large number of WS would be available and they need to be tested and evaluated in real time. While numerous test input generation techniques are available to generate test inputs, the oracle or the expected output of these test input is often difficult to obtain. One way to obtain the oracle in this case is to give the same input to multiple WS and to establish the oracle by a majority voting. This is based on the assumption that faulty WS often would not produce consistent results, and thus if a majority can be reached, the oracle can be established statistically. However, even correct WS may still produce slightly different outputs, and thus the majority-voting scheme must be carefully designed to distinguish correct but slightly variant output from truly incorrect output. This paper proposes a hierarchical classification based on simulated annealing and multi-dimensional Chi-square statistical techniques to analyze data to see if a majority can be reached. The algorithm is evaluated by a comprehensive simulated data as well as actual data. The data show that the proposed algorithm is effective even in a difficult situation where clusters of WS produce clusters of output.\",\n \"Title: Testability of Software in Service-Oriented Architecture\\nYear: 2006\\n\\nAbstract: Service-Oriented Architecture (SOA) is a system architecture in which a collection of loosely coupled services communicate with each other using standard interfaces and message-exchanging protocols. As an emerging technology in software development, the SOA presents a new paradigm, and it affects the entire software development cycle including analysis, specification, design, implementation, verification, validation, maintenance and evoluation. This paper proposes several testability evaluation criteria for SOA software, which serves as a reference for both service providers and application builders to evaluate the test support to SOA software. The proposed evaluation criteria are illustrated in a stock-trading case study.\",\n \"Title: Process Specification and Modeling Language for Service-Oriented Software Development\\nYear: 2007\\n\\nAbstract: This paper focuses on the service-oriented system engineering issues using PSML (Process Specification and Modeling Language) framework. The key innovations of the framework are the PSML-based service-oriented software development and Single Model with Multiple Analyses (SMMA) model-driven architecture. SMMA uses one integrated core model, the PSML model, to derive other models for code generation simulation, and various analyses, which leads to the service-oriented system engineering.\",\n \"Title: SOA Simulation and Verification by Event-Driven Policy Enforcement\\nYear: 2008\\n\\nAbstract: The verification of SOA (Service-Oriented Architecture) applications is important, and, simulation is a promising method because it provides runtime behavior and performance analysis. This paper uses a BPEL engine as a simulation engine to simulate SOA applications, and proposes an event- driven policy enforcement framework to verify the SOA applications during simulation.\",\n \"Title: On Testing and Evaluating Service-Oriented Software\\nYear: 2008\\n\\nAbstract: As service-oriented architecture matures and more Web services become available, developers must test an ever-increasing volume of services. A framework that defines and evaluates test-case potency based on coverage relationships can reduce testing effort while maintaining testing's effectiveness.\",\n \"Title: Biased covering arrays for progressive ranking and composition of Web Services\\nYear: 2007\\n\\nAbstract: Service-oriented computing is a new software development paradigm that allows application builders to choose from many available services. The challenges are to efficiently determine which services are the most appropriate to combine into an application based on concerns such as functionalities, licensing costs, and known reliability. Group testing has addressed some issues on how to select a small subset of candidate services. We expand upon the group testing methodology with a greedy algorithm that generates biased covering arrays for interactive testing of the services selected by group testing.\",\n \"Title: A green-aware virtual machine migration strategy for sustainable datacenter powered by renewable energy\\nYear: 2015\\n\\nAbstract: •We propose a green-aware approach for managing VMs in datacenters.•Models are established for datacenters, VMs and power consumption.•An optimization problem is formulated to incorporate revenue and costs.•Three strategies designed to manage VMs dynamically are implemented.•The proposed approach is proved to be feasible in utilizing green energy.\",\n \"Title: Developing a Security Robot in Service-Oriented Architecture\\nYear: 2008\\n\\nAbstract: Service composition accelerates rapid application development, service reuse, and complex service consummation, thus, quantitative characteristics such as service execution throughput should be evaluated to measure the system performance. Based on Continuous ...\",\n \"Title: Web Service Group Testing with Windowing Mechanisms\\nYear: 2005\\n\\nAbstract: ASTRAR provides a framework for testing Web Services (WS) using the group testing technique. This paper extends the basic two-phase testing process and introduces the windowing mechanism to further improve testing efficiency. Rather than testing a large number of WS simultaneously, WS are divided into subsets called windows and testing is exercised window by window. Testing results are analyzed for different strategies such as using all of the historical data, using the most recent windows, and using the current window only. Based on the results, test cases are ranked according to their potency to detect faults; and oracles and the confidence level of each oracle are established for individual test cases at run-time. In addition, different strategies are proposed to determine the optimal window size at run-time. By incorporating the windowing mechanism, the two-phase training and volume testing process becomes a continuous learning process and the basic group testing process becomes more adaptive to dynamically changing environment.\",\n \"Title: WSDL-Based Automatic Test Case Generation for Web Services Testing\\nYear: 2005\\n\\nAbstract: In the past a few years, we witnessed a rapid progress in Service-Oriented Computing (SOC), which represents a paradigm shift from the current mainstream Object-Oriented Computing (OOC) paradigm to the SOC paradigm. This paradigm shift is changing the ...\",\n \"Title: Automatically Building Service Evaluation Metadata in a Grid Environment\\nYear: 2006\\n\\nAbstract: This paper presents a mechanism that automatically build evaluation metadata for grid services by using the information from the execution of different applications. A new MetaService AMDBS, Automatic Metadata Building Service, is designed to support this mechanism. The typical feature of this mechanism is that it can get not only the absolute evaluation information, but also the relative global ranking result through the collaboration of different AMDBSs. Web Service group testing is used as an example of a grid application to accelerate the process of evaluation metadata building. Simulation experiment results show that the HP (Heavy-Powerful) algorithm which is designed based on the dynamic evaluation metadata can improve the application performance significantly, compared with the RR (Round-Robin) algorithm which does not use the evaluation metadata. The effect of using evaluation metadata in different task and resource conditions is also demonstrated by experiment results.\",\n \"Title: Consumer-Centric Service-Oriented Architecture: A New Approach\\nYear: 2006\\n\\nAbstract: This paper extends the current Service-Oriented Architecture (SOA) to introduce a Consumer-Centric Service-Oriented Architecture (CCSOA) paradigm. The current SOA is producer-centric, because the basic idea is that service providers publish services that they produce and let the consumers to search available services to compose their applications. CCSOA focuses on consumers' publishing the services they need and even the applications they need. The service providers must produce services that are in need. This new paradigm extends the design and code sharing, and thus further improves the software productivity. This paper presents the concepts, architecture, enabling techniques, and illustrative examples.\",\n \"Title: A Security Authentication Protocol for Trusted Domains in an Autonomous Decentralized System\\nYear: 2016\\n\\nAbstract: AbstractSoftware Defined Network SDN architecture has been widely used in various application domains. Aiming at the authentication and security issues of SDN architecture in autonomous decentralized system ADS applications, securing the mutual trust among the autonomous controllers, we combine trusted technology and SDN architecture, and we introduce an authentication protocol based on SDN architecture without any trusted third party between trusted domains in autonomous systems. By applying BAN predicate logic and AVISPA security analysis tool of network interaction protocol, we can guarantee protocol security and provide complete safety tests. Our work fills the gap of mutual trust between different trusted domains and provides security foundation for interaction between different trusted domains.\",\n \"Title: Analyzing and visual programming internet of things and autonomous decentralized systems.\\nYear: 2016\\n\\nAbstract: The development of Internet of Things, fueled by cloud computing and big data processing from upper level, and by ubiquitous sensory and actuator devices from the lower level, has taken a sharp turn towards integrating the entire information, computing, communication, and control systems. This special issue selected seven papers from the 2015 IEEE twelfth International Symposium on Autonomous Decentralized Systems (ISADS). These papers cover the latest research on IoT and ADS based system science and system engineering methods; the wearable sensor network development and applications; and data analysis for security and reliability in IoT and ADS applications. As an addition to these selected topics, this guest editorial paper also adds IoT education and dissemination aspects to this special issue. As the IoT research and applications expand explosively into all the domains, schools and universities must prepare students to understand and to be able to program the IoT devices. This paper presents a visual programming environment that allows students without programming background to learn the key concepts of computing and IoT devices, and to program IoT devices into different application systems.\",\n \"Title: A Novel Multi-Focus Image Fusion Method Based on Stochastic Coordinate Coding and Local Density Peaks Clustering.\\nYear: 2016\\n\\nAbstract: The multi-focus image fusion method is used in image processing to generate all-focus images that have large depth of field (DOF) based on original multi-focus images. Different approaches have been used in the spatial and transform domain to fuse multi-focus images. As one of the most popular image processing methods, dictionary-learning-based spare representation achieves great performance in multi-focus image fusion. Most of the existing dictionary-learning-based multi-focus image fusion methods directly use the whole source images for dictionary learning. However, it incurs a high error rate and high computation cost in dictionary learning process by using the whole source images. This paper proposes a novel stochastic coordinate coding-based image fusion framework integrated with local density peaks. The proposed multi-focus image fusion method consists of three steps. First, source images are split into small image patches, then the split image patches are classified into a few groups by local density peaks clustering. Next, the grouped image patches are used for sub-dictionary learning by stochastic coordinate coding. The trained sub-dictionaries are combined into a dictionary for sparse representation. Finally, the simultaneous orthogonal matching pursuit (SOMP) algorithm is used to carry out sparse representation. After the three steps, the obtained sparse coefficients are fused following the max L1-norm rule. The fused coefficients are inversely transformed to an image by using the learned dictionary. The results and analyses of comparison experiments demonstrate that fused images of the proposed method have higher qualities than existing state-of-the-art methods.\",\n \"Title: A trusted access method in software-defined network.\\nYear: 2017\\n\\nAbstract: In software-defined networks (SDN), most controllers do not have an established control function for endpoint users and access terminals to access network, which may lead to many attacks. In order to address the problem of security check on access terminals, a secure trusted access method in SDN is designed and implemented in this paper. The method includes an access architecture design and a security access authentication protocol. The access architecture combines the characteristics of the trusted access technology and SDN architecture, and enhances the access security of SDN. The security access authentication protocol specifies the specific structure and implementation of data exchange in the access process. The architecture and protocol implemented in this paper can complete the credibility judgment of the access device and user's identification. Furthermore, it provides different trusted users with different network access permissions. Experiments show that the proposed access method is more secure than the access method that is based on IP address, MAC address and user identity authentication only, thus can effectively guarantee the access security of SDN.\",\n \"Title: Robot Cloud: Bridging the power of robotics and cloud computing.\\nYear: 2017\\n\\nAbstract: Cloud computing is shaping the cyber world and evolves as a key computing and service platform for sharing resources including platforms, software applications and everything in the form of services. This is known “X as a Service”. Although it brings our age unparalleled computing ability and economic benefits, the application of cloud computing is still limited currently in the cyberspace due to the cloud services can only reside in cloud instead of our daily life environment. In fact, there are still a plethora of physical position based on-site service demands that cloud computing could help little due to the “cyber limitation”. In this paper, we aim to integrate the cyber world and the physical world by bringing up the idea of “Robot Cloud” to bridge the power of robotics and cloud computing. To make it possible, we design a novel Robot Cloud stack to support our idea and adopt the service-oriented architecture (SOA) to make the functional modules in the Robot Cloud more flexible, extensible and reusable. Then we develop a prototype of Robot Cloud using the popular Google App Engine to demonstrate our design method. Finally, we conduct the simulation experiments with a “robot show” application scenario to evaluate our scheduling policy and identify the effect of different request distributions and robot center solutions.\",\n \"Title: A Distributed Proactive Service Framework for Crowd-Sensing Process\\nYear: 2017\\n\\nAbstract: With the wide deployment of various kinds of sensors in fixed infrastructures and in mobile devices, technologies and applications of crowd-sensing has drawn attentions in the fields of mobile computing. This paper studies the design of frameworks for crowd-sensing process in a distributed environment. We discuss the realization of the compatibilities of devices and services, as well as the algorithms of dealing with transmitting and accessing large amount of sensing data. We present a new distributed crowd-sensing framework called DASF, which is based on context data servers. The framework consists of three layers: hardware device layer, context data layer, and smart service layer. The key innovations and features of the framework are illustrated in detail. Through experiments and results analyses, DASF is shown to have good compatibility in heterogeneous device platforms, and it is capable of dealing with heavy load of accessing with practical significance.\",\n \"Title: Dynamic Resource Allocation Algorithm for Container-Based Service Computing\\nYear: 2017\\n\\nAbstract: Cloud computing and virtualization technologies play important roles in modern service-oriented computing paradigm. More conventional services are being migrated to virtualized computing environments to achieve flexible deployment and high availability. We introduce a schedule algorithm based on fuzzy inference system (FIS), for global container resource allocation by evaluating nodes' statuses using FIS. We present the approaches to build containerized test environment and validates the effectiveness of the resource allocation policies by running sample use cases. Experiment results show that the presented infrastructure and schema derive optimal resource configurations and significantly improves the performance of the cluster.\",\n \"Title: Robot as a Service in Information Science & Electronic Engineering Education\\nYear: 2017\\n\\nAbstract: This paper reports the newly designed programming course developed and taught at Zhejiang University for a freshman class majoring in information science and electronic engineering, and disseminated to many other universities, to address the enrollment crisis as reported by ACM Curriculum Committee Review Task Force. The course teaches the basic information science and electronic engineering concepts and gives the students practical programming experience through robotics programming. The initial curriculum and the ongoing improvement of the course are presented. The course started with its experiment environment using ASU Visual IoT/Robotics Programming Environment (VIPLE). The environment supports a variety of platforms, including open architecture-based robots, such as Intel robots, PCDuino robots, vendor-specific robots, such as Lego EV3, as well as simulated robots, such as Web simulated robots in HTML5 and Unity-based 3D robots.\",\n \"Title: Visual IoT/Robotics Programming Language in Pi-Calculus\\nYear: 2017\\n\\nAbstract: As IoT/robotics research and applications expand explosively into many domains in computing, information, and control systems, schools and universities must prepare students to understand and be able to program IoT devices and robots. However, programming IoT and physical devices is hard and depends on good understanding of hardware and low-level programming. Workflow and visual programming environments have been developed to address this issue, including MIT App Inventor, Microsoft Robotics Developer Studio and VPL (Visual Programming Language), and Intel Service Orchestration Layer. We have developed a new visual programming language and its development environment: ASU VIPLE (Visual IoT/Robotics Programming Language Environment). ASU VIPLE is specifically developed to support different device platforms. It supports LEGO EV3 and all IoT devices based on an open architecture. ASU VIPLE integrates engineering design process, workflow, fundamental programming concepts, control flow, parallel computing, and event-driven programming seamlessly into the curriculum. It has been pilot tested at Arizona State University in summers 2015 and 2016, and is now taught in an ASU regular class, Introduction to Engineering. It has been adopted by numerous universities around the world. This paper focuses on the mathematical model of ASU VIPLE. π-calculus is used to describe the basic activities in VIPLE, as well as the workflow defined by the basic activities.\",\n \"Title: Fault-diagnosis for reciprocating compressors using big data and machine learning.\\nYear: 2018\\n\\nAbstract: Reciprocating compressors are widely used in petroleum industry. A small fault in reciprocating compressor may cause serious issues in operation. Traditional regular maintenance and fault diagnosis solutions cannot efficiently detect potential faults in reciprocating compressors. This paper proposes a fault-diagnosis system for reciprocating compressors. It applies machine-learning techniques to data analysis and fault diagnosis. The raw data is denoised first. Then the denoised data is sparse coded to train a dictionary. Based on the learned dictionary, potential faults are finally recognized and classified by support vector machine (SVM). The system is evaluated by using 5-year operation data collected from an offshore oil corporation in a cloud environment. The collected data is evenly divided into two halves. One half is used for training, and the other half is used for testing. The results demonstrate that the proposed system can efficiently diagnose potential faults in compressors with more than 80% accuracy, which represents a better result than the current practice.\",\n \"Title: Morphology-based visible-infrared image fusion framework for smart city.\\nYear: 2018\\n\\nAbstract: Sparse representation-based approaches are often applied to image fusion. Owing to the difficulties of obtaining a complete and non-redundant dictionary, this paper proposes a hierarchical image fusion framework that applies layer-by-layer deep learning techniques to explore the detailed information of images and extract key information of images for dictionary learning. According to morphological similarities, this paper clusters source image patches into smooth, stochastic, and dominant orientation patch group. High-frequency and low-frequency components of three clustered image-patch groups are fused by max-L1 and L2-norm based weighted average fusion rule respectively. The fused low-frequency and high-frequency components are combined to obtain the final fusion results. The comparison experimentations confirm the feasibility and effectiveness of the proposed image fusion solution.\",\n \"Title: Tenant-centric Sub-Tenancy Architecture in Software-as-a-Service\\nYear: 2016\\n\\nAbstract: Multi-tenancy architecture (MTA) is often used in Software-as-a-Service (SaaS) and the central idea is that multiple tenant applications can be developed using components stored in the SaaS infrastructure. Recently, MTA has been extended to allow a tenant application to have its own sub-tenants, where the tenant application acts like a SaaS infrastructure. In other words, MTA is extended to STA (Sub-Tenancy Architecture). In STA, each tenant application needs not only to develop its own functionalities, but also to prepare an infrastructure to allow its sub-tenants to develop customized applications. This paper applies Crowdsourcing as the core to STA component in the development life cycle. In addition, to discovering adequate fit tenant developers or components to help build and compose new components, dynamic and static ranking models are proposed. Furthermore, rank computation architecture is presented to deal with the case when the number of tenants and components becomes huge. Finally, experiments are performed to demonstrate that the ranking models and the rank computation architecture work as design.\",\n \"Title: Technologies for developing a smart city in computational thinking.\\nYear: 2018\\n\\nAbstract: Building a smart city involves almost all the aspects of social, economic, and technological issues. This paper gives a brief survey and overview of the latest technologies for building a smart city. It covers IoT, device as a service, service-oriented computing and cloud computing as the infrastructure, big data analysis and processing for data mining, and artificial intelligence. A visual programming language for IoT and robotics application development is also introduced, which offers a tool for architects and developers to define the applications using computational thinking and workflow of existing services and components.\",\n \"Title: Visual programming language environment for different IoT and robotics platforms in computer science education\\nYear: 2018\\n\\nAbstract: This study presents the authors’ recent research and application of a new visual programming language and its development environment: VIPLE (Visual IoT/Robotics Programming Language Environment) at Arizona State University (ASU). ASU VIPLE supports a variety of IoT devices and robots based on an open architecture. Based on computational thinking, VIPLE supports the integration of engineering desi...\",\n \"Title: Modeling and simulation of improved artificial bee colony algorithm with data-driven optimization\\nYear: 2019\\n\\nAbstract: •This paper studies the driving force of additional data for ABC.•An improved artificial bee colony algorithm with data-driven is proposed.•The searching process is driven by directional guiding data and local data.•Our work is compared with some ABC-based and nature-inspired algorithms.\",\n \"Title: A Spark-Based Open Source Framework for Large-Scale Parallel Processing of Rich Text Documents\\nYear: 2021\\n\\nAbstract: The large amount of unstructured educational data is an important data source of educational big data analysis. However, there is a lack of efficient and simple distributed solutions to process these unstructured documents. To address this problem, this study proposes a Spark-based parallel processing framework of large-scale rich text documents (mainly as MS Word documents), which can seamlessly ...\",\n \"Title: Twe-Wsd: An Effective Topical Word Embedding Based Word Sense Disambiguation\\nYear: 2021\\n\\nAbstract: Word embedding has been widely used in word sense disambiguation (WSD) and many other tasks in recent years for it can well represent the semantics of words. However, the existing word embedding methods mostly represent each word as a single vector, without considering the homonymy and polysemy of the word; thus, their performances are limited. In order to address this problem, an effective topical word embedding (TWE)-based WSD method, named TWE-WSD, is proposed, which integrates Latent Dirichlet Allocation (LDA) and word embedding. Instead of generating a single word vector (WV) for each word, TWE-WSD generates a topical WV for each word under each topic. Effective integrating strategies are designed to obtain high quality contextual vectors. Extensive experiments on SemEval-2013 and SemEval-2015 for English all-words tasks showed that TWE-WSD outperforms other state-of-the-art WSD methods, especially on nouns.\",\n \"Title: Multi-view 3D model retrieval based on enhanced detail features with contrastive center loss\\nYear: 2022\\n\\nAbstract: In recent years, 3D model retrieval has become a hot topic. With the development of deep learning technology, many state-of-the-art deep learning based multi-view 3D model retrieval algorithms have emerged. One of the major challenges in view-based 3D model retrieval is how to achieve rotation invariant. MVCNN (Multi-View Convolutional Neural Networks) achieving higher performance while maintaining rotation invariant. However, the element-wise maximum operation across the views leads to the loss of detailed information. To address this problem, in this paper, we use a deep cross-modal learning method to treat the features of different views as different modal features. First, we select two of the views as the input of the deep multimodal learning method. Then we combine the proposed method with an improved contrastive center loss, so that we can align the features in the same subspace and obtain a higher discriminative fused feature. Experimental results show that the training of the proposed CNN (Convolutional Neural Networks) model is based on the existing MVCNN pre-trained model, which takes only 18 epochs to converge, and it obtains 90.07% in terms of mAP (mean average precision) using only the MVCNN as the backbone, which is comparable to the feature fusion algorithm PVRNet (Point-View Relation Neural Network) and much higher than the mAP of MVCNN (80.2%). The experimental results demonstrated that the proposed method avoids explicitly learning the weights for fusion of different view features, while incorporating more details into the 3D model’s final descriptor can improve the retrieval results.\",\n \"Title: Multi-head self-attention based gated graph convolutional networks for aspect-based sentiment classification\\nYear: 2022\\n\\nAbstract: Aspect-based sentiment classification aims to predict the sentiment polarity of specific aspects appeared in a sentence. Nowadays, most current methods mainly focus on the semantic information by exploiting traditional attention mechanisms combined with recurrent neural networks to capture the interaction between the contexts and the targets. However, these models did not consider the importance of the relevant syntactical constraints. In this paper, we propose to employ a novel gated graph convolutional networks on the dependency tree to encode syntactical information, and we design a Syntax-aware Context Dynamic Weighted layer to guide our model to pay more attention to the local syntax-aware context. Moreover, Multi-head Attention is utilized for capturing both semantic information and interactive information between semantics and syntax. We conducted experiments on five datasets and the results demonstrate the effectiveness of the proposed model.\",\n \"Title: Bayesian estimation-based sentiment word embedding model for sentiment analysis\\nYear: 2022\\n\\nAbstract: Sentiment word embedding has been extensively studied and used in sentiment analysis tasks. However, most existing models have failed to differentiate high-frequency and low-frequency words. Accordingly, the sentiment information of low-frequency words is insufficiently captured, thus resulting in inaccurate sentiment word embedding and degradation of overall performance of sentiment analysis. A Bayesian estimation-based sentiment word embedding (BESWE) model, which aims to precisely extract the sentiment information of low-frequency words, has been proposed. In the model, a Bayesian estimator is constructed based on the co-occurrence probabilities and sentiment probabilities of words, and a novel loss function is defined for sentiment word embedding learning. The experimental results based on the sentiment lexicons and Movie Review dataset show that BESWE outperforms many state-of-the-art methods, for example, C&W, CBOW, GloVe, SE-HyRank and DLJT1, in sentiment analysis tasks, which demonstrate that Bayesian estimation can effectively capture the sentiment information of low-frequency words and integrate the sentiment information into the word embedding through the loss function. In addition, replacing the embedding of low-frequency words in the state-of-the-art methods with BESWE can significantly improve the performance of those methods in sentiment analysis tasks.\",\n \"Title: Polymorphic graph attention network for Chinese NER\\nYear: 2022\\n\\nAbstract: •Lexicon information has been proved to be very useful in Chinese Named Entity task.•The existing methods make insufficient use of lexicon information.•We propose a Polymorphic Graph Attention Network for fusion lexicon into character.•Our method can be easily combined with pre-trained or sequence encoding model.•The proposed method supports multi-head attention and has excellent inference speed.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":130,"string":"130"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":64,"string":"64"}}},{"rowIdx":65,"cells":{"question_id":{"kind":"string","value":"Kia Makki"},"question":{"kind":"string","value":"Generate an abstract for the title \"Graph-based object-oriented approach for structural and behavioral representation of multimedia data\" using the following items: 1. Multimedia Information Systems\n2. Object-Oriented Data Model\n3. Graph-Based Data Model\n4. Schema Versioning Approach\n5. Perspective Version Abstraction"},"answer":{"kind":"string","value":"The management of multimedia information poses special requirements for multimedia information systems. Both representation and retrieval of the complex and multifaceted multimedia data are not easily handled with the flat relational model and require new data models. In the last several years, object-oriented and graph-based data models are actively pursued approaches for handling the multimedia information. In this paper the characteristics of the novel graph-based object-oriented data model are presented. This model represents the structural and behavioral aspects of data that form multimedia information systems. It also provides for handling the continuously changing user requirements and the complexity of the schema and data representation in multimedia information systems using the schema versioning approach and perspective version abstraction."},"correct_answer":{"kind":"string","value":"The management of multimedia information poses special requirements for multimedia information systems. Both representation and retrieval of the complex and multifaceted multimedia data are not easily handled with the flat relational model and require new data models. In the last several years, object-oriented and graph-based data models are actively pursued approaches for handling the multimedia information. In this paper the characteristics of the novel graph-based object-oriented data model are presented. This model represents the structural and behavioral aspects of data that form multimedia information systems. It also provides for handling the continuously changing user requirements and the complexity of the schema and data representation in multimedia information systems using the schema versioning approach and perspective version abstraction."},"documents":{"kind":"list like","value":["Title: A context-aware prefetching strategy for mobile computing environments\nYear: 2006\n\nAbstract: In a mobile wireless environment, the latency (time-delay) observed by a user before s/he receives up-to-date information may be high because of the limited available bandwidth. An efficient prefetching strategy must be tailored to the competing goals of keeping latency low (which requires more prefetching) and reducing resource waste in a mobile environment, which is characterized by scarce bandwidth and resource-poor user devices. Current research is based on the tangent velocity approach, which is effective only within a short time interval and has a high cost of continuous geometric estimations.This paper proposes a cache management method that maintains the mobile terminal's cache content by prefetching data items with maximum benefit and evicting cache data entries with minimum benefit. The data item benefit is evaluated based on the user's query context defined as a set of constraints (predicates), which define both the movement pattern and information context requested by the mobile user. A context-aware cache is formed and maintained using a set of neighboring locations (we call the prime list) restricted by the validity of the data fetched from the server. Simulation results show that the proposed strategy using different levels of granularity can greatly improve the system performance in terms of cache hit ratio.","Title: Machine Learning On Congestion Analysis Based Real-Time Navigation System\nYear: 2011\n\nAbstract: In the metropolitan region, most congestion or traffic jams are caused by the uneven distribution of traffic flow that creates bottleneck points where the traffic volume exceeds the road capacity. Additionally, unexpected incidents are the next most probable cause of these bottleneck regions. Moreover, most drivers are driving based on their empirical experience without awareness of real-time traffic situations. This unintelligent traffic behavior can make the congestion problem worse. Prediction based route guidance systems show great improvements in solving the inefficient diversion strategy problem by estimating future travel time when calculating accurate travel time is difficult. However, performances of machine learning based prediction models that are based on the historical data set degrade sharply during a congestion situation. This paper develops a new navigation system for reducing travel time of an individual driver and distributing the flow of urban traffic efficiently in order to reduce the occurrence of congestion. Compared with previous route guidance systems, the results reveal that our system, applying the advanced multi-lane prediction based real-time fastest path (AMPRFP) algorithm, can significantly reduce the travel time especially when drivers travel in a complex route environment and face frequent congestion problems. Unlike the previous system,(1) it can be applied either for single lane or multi-lane urban traffic networks where the reason for congestion is significantly complex. We also demonstrate the advantages of this system and verify the results using real highway traffic data and a synthetic experiment.","Title: Ensemble Of Machine Learning Algorithms For Intrusion Detection\nYear: 2009\n\nAbstract: Ensemble-classifier is a technique that uses a combination of multiple classifiers to reach a more precise inference result than a single classifier. In this paper, a three-layer hierarchy multi-classifier intrusion detection architecture is proposed to promote the overall detection accuracy. For making every individual classifier is independent from others, each uses a diverse soft computing technique as well as different feature subset. In addition, the performances of a variety of combination methods that fuse the outputs from classifiers are studied. In the experiments, DARPA KDD99 intrusion detection data set is chosen as the evaluation tools. The results show that our approach achieves a better performance than that of a single classifier.","Title: Design And Evaluation Of An Efficient Traffic Control Scheme For Integrated Voice, Video, And Data Over Asynchronous Transfer Mode Networks: Explicit Allowed Rate Algorithm\nYear: 1999\n\nAbstract: Asychronous transfer mode (ATM) networks are high-speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of physical bandwidth. Unlike constant bit-rate (CBR) traffic, the bandwidth reserved by variable bit-rate (VBR) traffic is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit-rate (ABR) traffic. As the bandwidth used by VER traffic changes, available bandwidth for ABR traffic varies; i.e., available bandwidth for ABR traffic is inversely proportional to the bandwidth used by the VER traffic. Based on this fact, a rate-based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), in both LAN and WAN environments. Simulation of all three algorithms are conducted under both congestion and fairness configurations with simultaneous generation of CBR, rt-VBR, nrt-VBR and ABR traffic. The results show that, with very small over-head on the switch, EARA significantly decreases the required buffer space and improves the network throughput. Copyright (C) 1999 John Wiley & Sons, Ltd.","Title: A coherent architecture for a temporal object data base management system\nYear: 1994\n\nAbstract: The last decade has witnessed the emergence of practical general-purpose data base management systems (DBMS) as “state of the art” technology. In consequence, these systems are now widely used in a variety of application environments. However, many such systems were designed to capture current data, i.e., a snapshot of reality, but are insufficient for those applications in which past or future data are also required. Even so, there has been little effort to design temporal DBMS, and currently there are no prominent commercial temporal DBMS. This article identifies, explores, and provides an approach to designing a coherent architecture for a temporal object DBMS (TODBMS). It specifically involves the design, development, and implementation of TODBMS. We introduce the basic features of our system and provide an overview of the functionalities supported. In addition, we identify the major components of TODBMS and define the types of services each component should offer, as well as common abstractions and interfaces for these components. Application environments include management and geographic information systems, data base visualization, and robotics.","Title: Using logical rings to solve the distributed mutual exclusion problem with fault tolerance issues\nYear: 2000\n\nAbstract: In this paper, we investigate distributed mutual exclusion algorithms and delineate the features of a new distributed mutual exclusion algorithm. The basis of the algorithm is the logical ring structure employed in token-based mutual exclusion algorithms. Specifically, there exists dynamic properties of the logical ring that, given certain restrictions regarding message traffic flow, passively give useful information about the location of the token. Effectively, the algorithm demonstrates a type of 'intelligent routing' that identifies useful shortcuts in the routing of the token. The result is a reduction in the total number of messages exchanged prior to the execution of the critical section as compared to the algorithm proposed by Fu and Tzeng [3]. Furthermore, the algorithm allows for an increased degree of fairness in a lightly loaded system than that allowed by Fu and Tzeng's algorithm. The paper also addresses failure recovery issues.","Title: Resource Management In The Next-Generation Integrated Wlan/3g Cellular Networks\nYear: 2007\n\nAbstract: The next-generation (4G) wireless communication systems focus on the seamless integration of various existing wireless communication networks, such as integrating the third-generation (3G) cellular networks and wireless local area network (WLAN). Resource management (RM) is one of the essential techniques to improve both overall resource utilization and quality-of-service (QoS) provisioning. In this paper, we proposed a novel joint resource management scheme with QoS provisioning. A joint call admission policy is derived to support heterogeneous network architecture, service types, user mobility characteristics, and QoS levels. To relieve traffic congestion, an optimal channel searching and replacement algorithm (oCSR) and passive handoff techniques are further developed to balance total system traffic between WLAN and 3G cellular network as well as to reduce average system QoS cost, such as weighted blocking probability. Theoretical analysis and simulation results show that our scheme outperforms both traditional disjoint RM and joint RM without optimization.","Title: Achieve constant performance guarantees using asynchronous crossbar scheduling without speedup\nYear: 2010\n\nAbstract: Buffered crossbar switches are special crossbar switches with a small exclusive buffer at each crosspoint of the crossbar. They demonstrate unique advantages, such as variable length packet handling and distributed scheduling, over traditional unbuffered crossbar switches. The current main approach for buffered crossbar switches to provide performance guarantees is to emulate push-in-first-out output queued switches. However, such an approach has several drawbacks, and in particular it has difficulty in providing tight constant performance guarantees. To address the issue, we propose in this paper the guaranteed-performance asynchronous packet scheduling (GAPS) algorithm for buffered crossbar switches. GAPS intends to provide tight performance guarantees, and requires no speedup. It directly handles variable length packets without segmentation and reassembly, and makes scheduling decisions in a distributed manner. We show by theoretical analysis that GAPS achieves constant performance guarantees. We also prove that GAPS has a bounded crosspoint buffer size of 3L, where L is the maximum packet length. Finally, we present simulation data to verify the analytical results and show the effectiveness of GAPS.","Title: Towards a framework for integrating multilevel secure models and temporal data models\nYear: 1994\n\nAbstract: Within many organizations the number of databases containing classified or otherwise sensitive data is increasing rapidly. Access to these databases must be restricted and controlled to limit the unauthorized disclosure, or malicious modification of data contained in them. However, the conventional models of authorization that have been designed for database systems supporting the hierarchical, network and relational models of data do not provide adequate mechanisms to support controlled access of temporal objects and context based temporal information. In this paper we extend the multilevel secure relational model to capture the functionality required of a temporal database, i.e. a database that supports some aspect of time, not counting user-defined time. In particular we assign class access to bitemporal timestamped attributes, and give explicit security classifications to temporal elements.","Title: A Framework for Temporal Object Databases\nYear: 1992\n\nAbstract: The 3 Dimensional Information Space (3DIS) is a rich, extensible, object database model for information management. Here, we concentrate on extending the 3DIS to incorporate the semantics of time, and to support temporal data and the temporal evolution of data. We present a unique approach towards the synthesis of an integrated 3DIS model that supports the temporal aspects of data modeling in addition to the structural and dynamic ones, while preserving its original three dimensional geometric space features. This research presents a step towards defining the concepts and techniques for incorporating time in object databases, and provides a concrete experimental framework for demonstration thereof.","Title: MURU: A Multi-Hop Routing Protocol for Urban Vehicular Ad Hoc Networks\nYear: 2006\n\nAbstract: Vehicular ad hoc networks (VANETs) are going to be an important communication infrastructure in our life. Because of high mobility and frequent link disconnection, it becomes quite challenging to establish a robust multi-hop path that helps packet delivery from the source to the destination. This paper presents a multi-hop routing protocol, called MURU that is able to find robust paths in urban VANETs to achieve high end-to-end packet delivery ratio with low overhead. MURU tries to minimize the probability of path breakage by exploiting mobility information of each vehicle in VANETs. A new metric called expected disconnection degree (EDD) is used to select the most robust path from the source to the destination. MURU is fully distributed and does not incur much overhead, which makes MURU highly scalable for VANETs. The design is sufficiently justified through theoretical analysis and the protocol is evaluated with extensive simulations. Simulation results demonstrate that MURU significantly outperforms existing ad hoc routing protocols in terms of packet delivery ratio, packet delay and control overhead","Title: An Efficient Approximate Algorithm For Delay-Cost-Constrained Qos Routing\nYear: 2001\n\nAbstract: The problem of finding a path with two additive constraints is called multi-constrained path (MCP) problem in the literature. In this paper, we explore the MCP problem based on the idea of single mixed weight. Given two infeasible paths, it can be theoretically proved that a better path can possibly be found if we choose an appropriate parameter to construct the mixed weight. An approximate algorithm is thus proposed to solve the MCP problem. A large number of experiments on networks of different sizes demonstrate that this algorithm can make a correct judgment whether there is a feasible path or not with a very high probability. On the other band, the time complexity of this algorithm is very small since it only needs to execute Dijkstra's algorithm a limited number of times even for a network of relatively large size.","Title: Providing Performance Guarantees for Buffered Crossbar Switches without Speedup\nYear: 2009\n\nAbstract: Buffered crossbar switches are special crossbar switches with each crosspoint equipped with a small exclusive buffer. The crosspoint buffers decouple input ports and output ports, and simplify switch scheduling. In this paper, we propose a scheduling algorithm called Fair and Localized Asynchronous Packet Scheduling (FLAPS) for buffered crossbar switches, to provide tight performance guarantees. FLAPS needs no speedup for the crossbar and handles variable length packets without segmentation and reassembly (SAR.). With FLAPS, each input port and output port independently make scheduling decisions and rely on only local queue statuses. We theoretically show that a crosspoint buffer size of 4L is sufficient for FLAPS to avoid buffer overflow, where L is the maximum packet length. In addition, we prove that FLAPS achieves strong stability, and provides bounded delay guarantees. Finally, we present simulation data to verify the analytical results.","Title: Fuzzy Belief Reasoning for Intrusion Detection Design\nYear: 2007\n\nAbstract: In this paper, we propose a method to resolve uncertainty problems by incorporating fuzzy clustering technique and Dempster-Shafer theory. Also, the k- nearest neighbors (k-NN) technique is applied to speed up the detection process and C4.5 decision tree algorithm is used to improve the classification accuracy. For verifying the performance of our classifier, DARPA KDD99 Intrusion Detection Evaluation data set is used. We compare the results of our proposed approach with those of k-NN classifier, fuzzy k-NN classifier and evidence-theoretic k-NN classifier. The result indicates that our approach has a better performance than these from the other three classifiers.","Title: Communications via Systems-on-Chips Clustering in Large-Scaled Sensor Networks\nYear: 2008\n\nAbstract: In this paper, we have proposed a framework of systems-on-chips clustering in application to complicated sensor networks. The framework can be applied to address the communication issues in distributed and large-scaled sensor nodes in wireless sensor network application. There are two communication categories under consideration, i.e. intra-nodes and inter-nodes. Due to the potentially higher frequency in the signal propagation within the sensor node, the characteristics of the interconnect among various systems-on-chips cannot be described in the traditionally lumped R, L, C components. We adapt a distributed transmission line model to address such issues and possibly improve the reliability in the intra-nodes communication. Furthermore, based on the bandwidth requirements of each sensor node, the large-scaled senor network is proposed to be transformed into a maze diagram by a user defined threshold bandwidth, so that many existing approaches may be applied to determine the routing paths in the inter-nodes communication to improve the efficiency of the overall network.","Title: Collaborative Trust-Based Secure Routing in Multihop Ad Hoc Networks\nYear: 2004\n\nAbstract: In this paper we have proposed a secure routing protocol based on AODV for multihop ad hoc networks. Our protocol is unique in the sense that it is capable of finding a secure end-to-end route free of any malicious entity, thus resisting an internal attack within the network either in the form of compromised or disloyal nodes. We propose to find a secure and efficient route to a destination based on collaborative effort of all the nodes.","Title: A Future Location-Prediction Replacement Strategy For Mobile Computing Environments\nYear: 2006\n\nAbstract: While the traditional data shipping systems use physical information to organize data, a newer data caching technique maintains both associated answers (data items) of previous queries and their meaning (purpose). This form of information description is called semantic description, and it makes it possible to reason about and derive knowledge from the given description. In a distributed heterogeneous environment, such as the mobile environment, the semantic data caching paradigm is an important technique for improving the performance of wireless data dissemination systems. Data caching performance depends heavily on the replacement policy being used for the cache management. However, future location ambiguity, limited client resources and frequent client disconnections make cache management a challenge.This paper proposes a future location-aware cache replacement policy to manage a semantic cache. The proposed replacement policy uses the validity of the data fetched from the server and the neighboring locations to decide which of the cache entries is less likely to be needed in the future, and therefore, a good candidate to be evicted when cache space is needed. The replacement policy's preference for cached items to be evicted is modelled as a general function that declines with distance between the cell the candidate for replacement's cached item is bounded to and the query's bound cell. For better efficiency the overall replacement granularity is dynamically achieved along three levels: ring, cell and data item. Simulation study of the proposed approach shows that it outperforms both the least recently used (LRU) and furthest away replacement (FAR) schemes, where only temporal locality is considered. Moreover, the proposed scheme is easier to implement than the industry standard policies.","Title: The secure model for enterprise connectivity.\nYear: 2000\n\nAbstract: The need for implementing data security over the enterprise network model has been brought to the forefront of the e-commerce marketplace by an increasing amount of incidents involving the compromise of confidential data as well as the abuse of private information by electronic intruders. The priority of data that is being stored, distributed and processed over the network medium has led to a strong focus on the security of the data, and the security of systems that contain and distribute it. The ideal of this new prototype is an alternative mode of enforcing security on enterprise networks by using algorithms aimed at data fragmentation rather than encryption. While encryption provides a means for scrambling data through the use of complex algorithms, this model proposes a mechanism for fragmenting the data stream in a way that reconstruction is possible only within a zone deemed safe by the implementation process. By binding the reconstruction process to a logical location within the safe area, it is possible to enforce a high level of safety around the entire data link process. The compromise of all data fragments would not allow reconstruction into the original form without the necessary complimentary reconstruction algorithm. As another layer of security, the reconstruction algorithm would allow execution only from a predefined logical location on the enterprise domain, and would thus be rendered useless if executed from an intruder's location. This system ensures that the overhead involved with imposing higher encryption strengths is bypassed without the loss of the security enforced over the system.","Title: Estimated Replication Of Data In Wireless Sensor Networks\nYear: 2008\n\nAbstract: A wireless sensor network (WSN) can be envisaged as a distributed system where the sensor nodes (clients) continuously update the sensed information to the sink (server). In many real-time environments exact replica of data is not required by the end application to deduce the result. Data estimation/prediction techniques at the sink can be used to infer the desired output. The proposed design is an improvement of the model as proposed by Santini [1] which uses the traditional LMS algorithm to predict the desired output at the sink. In this work we solve the synchronization of mode problem in the Santini's model by effectively utilizing the the principles of adaptive filter theory. The focus of this paper is to make better use of communication resources in data replication platforms than approaches based on periodic refreshing.","Title: Waiting time of handoff calls for the wireless mobile networks with dependent calls arrival processes and impatient calls\nYear: 2000\n\nAbstract: This paper studies the quasi-waiting time, the actual waiting time of the handoff calls in the buffer and the actual call holding times of new calls for the mobile wireless networks, in which the new calls arrival processes may depend on the number of calls in the target cells and the handoff calls arrival processes from the given cell to the target cell are modeled to be dependent on the number of calls in the given cells. In particular, the caller in the buffer waiting for further communication may become impatient. We propose an analytical model and obtain the expressions of the quasi and actual waiting time of a handoff call in the buffer, and prove that the actual call holding time of a new call is exponential. Some special cases of our model used in previous traffic models of wireless and/or wireline communications are discussed. The results presented in this paper may provide guidelines for field data processing on updated wireless mobile network design and performance evaluation","Title: Reachability and reverse reachability analysis of CFSMs\nYear: 1996\n\nAbstract: Reachability analysis and the recently proposed reverse reachability analysis are two important verification techniques for communicating finite state machines (CFSM). The issue of the relative efficiency of reachability analysis and reverse reachability analysis is still unsettled. In this paper, we first propose a new theory of reachability and reverse reachability analysis. Based on the new theory, we discuss and analyse the suitability of these two reachability analysis methods. We then present a reachability evaluator which, given any network of CFSMs, will try to estimate the sizes of the reachable and reverse reachable state spaces by taking snapshots of the reachability and reverse reachability spaces. The core of the evaluator is the notion of random state generation with seed states, which extends the idea of random state exploration proposed in [1]. Results from example applications have shown that the evaluator provides an excellent guidance in choosing the better of the two methods.","Title: A token based distributed k mutual exclusion algorithm\nYear: 1992\n\nAbstract: The authors present an algorithm for solving the k mutual exclusion problem in a distributed system. The algorithm is token based, whereby a token is passed among sites. Only sites that either receive the token with a nonzero semaphore or receive the token with a zero semaphore and later receive a release message from a previous site are allowed to enter their critical sections. Attached to the token is a queue which lists the sites scheduled to receive the token and a general semaphore. In all cases except extremely light token request traffic, the number of messages per critical section execution can be expressed as a small constant. This constant approaches three in an extremely heavy token request environment.","Title: Efficient implementations of a delay-constrained least-cost multicast algorithm.\nYear: 2002\n\nAbstract: Constrained minimum Steiner tree (CMST) problem is a key issue in multicast routing with quality of service (QoS) support. Bounded shortest path algorithm (BSMA) has been recognized as one of the best algorithms for the CMST problem due to its excellent cost performance. This algorithm starts with a minimum-delay tree, and then iteratively uses a k-shortest-path (KSP) algorithm to search for a better path to replace a \\superedge\" in the existing tree, and consequently reduces the cost of the tree. The ma- jor drawback of BSMA is its high time complexity because of the use of the KSP algorithm. For this reason, we investigate in this paper the possibility of more ecien t implementations of BSMA by using dieren t methods to locate the target path for replacing a superedge. Our experimental results indicate that our methods can signican tly reduce the time complexity of BSMA without deteriorating the cost performance.","Title: On Petri nets and self-stabilization of communication protocols\nYear: 1996\n\nAbstract: With Petri nets as the concurrent model, the issue of self-stabilizing communication protocols is discussed. It is argued that self-stabilizing extensions of communication protocols should not interfere with their normal operations by giving a new definition of self-stabilizing extension and a ring net that meets the new definition. It is also argued that communication protocols are usually delay sensitive and timed Petri nets provide a more suitable formal model than ordinary Petri nets to express the self-stabilizing property. The possibility and suitability of using Petri nets with a new type of transitions, the max transitions, to express self-stabilizing communication protocols is explored. To facilitate practical implementations, two types of interferences, external and internal interferences, are formally identified and discussed","Title: Mobile Agents to Automate Fault Management in Wireless and Mobile Networks\nYear: 2000\n\nAbstract: This paper studies the automation of fault management of wireless and mobile networks. A network management protocol similar to SNMP with an integrated architecture using mobile agents will prove effective in fault management of such networks. In view of the above, we design a wireless network management protocol to support fault management. In particular, we use mobile agents to detect, diagnose and recover from faults in wireless and mobile networks.","Title: Inferring Internet Worm Temporal Characteristics\nYear: 2008\n\nAbstract: Internet worm attacks pose a significant threat to network security. In this work, we coin the term Internet worm tomography as inferring the characteristics of Internet worms from the observations of Darknet or network telescopes that are routable but unused IP addresses. Under the framework of Internet worm tomography, we attempt to infer worm temporal behaviors such as the host infection time and the worm infection sequence, and thus pinpoint patient zero. Specifically, we introduce statistical estimation techniques and propose method of moments, maximum likelihood, and linear regression estimators. We show analytically and empirically that our proposed estimators can better infer worm temporal characteristics than a naive estimator that has been used in the previous work.","Title: Fair Queueing Based Packet Scheduling for Buffered Crossbar Switches\nYear: 2009\n\nAbstract: Recent development in VLSI technology makes it feasible to integrate on-chip memories to crossbar switching fabrics. Switches using such crossbars are called buffered crossbar switches, in which each crosspoint has a small exclusive buffer. The crosspoint buffers decouple input ports and output ports, and reduce the switch scheduling problem to the fair queueing problem. In this paper, we present the fair queueing based packet scheduling scheme for buffered crossbar switches, which requires no speedup and directly handles variable length packets without segmentation and reassembly (SAR). The presented scheme makes scheduling decisions in a distributed manner, and provides performance guarantees. Given the properties of the actual fair queueing algorithm used in the scheduling scheme, we calculate the crosspoint buffer size bound to avoid overflow, and analyze the fairness and delay guarantees provided by the scheduling scheme. In addition, we use WF2Q, the fair queueing algorithm with the tightest performance guarantees, as a case study, and present simulation data to verify the analytical results.","Title: A context-aware cache structure for mobile computing environments\nYear: 2007\n\nAbstract: This paper proposes a cache management method that maintains a mobile terminal's cache content by prefetching data items with maximum benefit and evicting cache data entries with minimum benefit. The data item benefit is evaluated based on the user's query context which is defined as a set of constraints (predicates) that define both the movement pattern and the information context requested by the mobile user. A context-aware cache is formed and maintained using a set of neighboring locations (called the prime list) that are restricted by the validity of the data fetched from the server. Simulation results show that the proposed strategy, using different levels of granularity, can greatly improve system performance in terms of the cache hit ratio.","Title: An Agent-Based Mobile System\nYear: 1997\n\nAbstract: In this paper we propose a new mobile system architecture, called the Client-Representative-Agent-Server (CRAS) architecture. While developing this architecture, an attempt is being made to keep GRAS compatible existing distributed object management frameworks and standards.","Title: A Hybrid Method To Cellular Traffic Using Optic Beam Interconnects\nYear: 2000\n\nAbstract: We propose a new type of wireless system, which is to provide for multimedia, bandwidth upon demand and Quality of Service (QoS) to the user. The system proposes to disable the problem caused by the unavailability of wired access by inculcating large bandwidths upon demand to individual users. The scheme proposes the use of optical beams in interconnecting mobile-telephone-switching-offices (MTSO) with each other using distinct WDM measures in a multihop scenario. Small microcells capable of growing themselves and reducing back to their macro size are employed. Traffic is dealt with the anomalous expansion and contraction of these cells. A high data rate to individual users is provided upon by a FH-CDMA based system whereby the chip rate becomes proportional to the channel quality. This ad-hoc method of adaptive coding helps the user maintain a uniform data rate through out all times.Benefits of this approach are dealt with in great detail and issues of reliability and hand off as well as system diversity is dealt with. As a further approach is suggested the interaction of this system with an all-optical underlaying network.","Title: Attack distribution modeling and its applications in sensor network security\nYear: 2008\n\nAbstract: Defending against attack is the key successful factor for sensor network security. There are many approaches that can be used to detect and defend against attacks, yet few are focused on modeling attack distribution. Knowing the distribution models of attacks can help system estimate the attack probability and thus defend against them effectively and efficiently. In this paper, we use probability theory to develop a basic uniform model, a basic gradient model, an intelligent uniform model and an intelligent gradient model of attack distribution in order to adapt to different application environments. These models allow systems to estimate the attack probability of each node under a given position and time. Applying these models in system security designs can improve system security performance and decrease the overheads in nearly every security area. Based on these models, we describe a novel probability secure routing algorithm that is effective to defend against attacks whether they are detected or not. Besides this application, we also introduce some other applications, such as secure routing that can save systems available energy and resources while still providing enough security, detecting attack, and key management.","Title: A Middleware-Based Architecture to Support Transparent Data Access by Mobile Users in Heterogeneous Environments\nYear: 2000\n\nAbstract: Mobile computing is becoming more and more pervasive, liberating users from the confines of wired networks. At the same time, transparent access to heterogeneous, distributed information sources has become a reality in wired computing. Obviously, this kind of access is highly desirable for mobile users, too. However, current architectures for transparent information access do not take the specific needs of mobile users into account, while existing architectures for mobile computing do not support transparent access well. For the future growth of the usage of mobile computing it is of utmost importance that instead of individually developed, isolated extensions to the existing architectures, the research community agrees on a strong, standardized middleware platform extending both existing mobile architectures and existing information access architectures to ensure mobile access in heterogeneous environments. In this paper we propose such a platform.","Title: A new storage organization for temporal data bases\nYear: 1994\n\nAbstract: A temporal data base needs to maintain large amounts of data, which causes long delays in accessing information. In this article, we design and develop an efficient storage structure for maintaining both current and historical data. Our strategy consists of two storage organizations, one for current versions and the other for history versions. The organization for current versions follows an efficient storage organization of a conventional nontemporal data base. However, for maintaining the history versions of each item in the data base, we use an extended version of a Fibonacci heap, referred to as a history version heap. The novelty of our approach resides in its ability to insert a new version for an item into the data base in O (1) amortized time and retrieve the oldest version of an item in O (1) amortized time. These bounds are irrespective of the number of existing versions for that item. In addition, we can access or delete any version of a given item in logarithmic amortized time. Because our approach treats the current store and history store differently, it uses different access methods for each store possible.","Title: On optimizing compatible security policies in wireless networks\nYear: 2006\n\nAbstract: This paper deals with finding the maximum number of security policies without conflicts. By doing so we can remove security loophole that causes security violation. We present the problem of maximum compatible security policy and its relationship to the problem of maximum acyclic subgraph, which is proved to be NP-hard. Then we present a polynomial-time approximation algorithm and show that our result has approximation ratio 1 + 1/k for any integer k with complexity O(Nk+1).","Title: Lossy Communicating Finite State Machines\nYear: 2004\n\nAbstract: network of communicating finite state machines (CFSM) consists of a set of finite state machines that communicate asynchronously with each other over (potentially) unbounded FIFO channels by sending and receiving typed messages. As a concurrency model, CFSMs has been widely used to specify and validate communications protocols. In this paper we propose to extend the classical CFSM model by introducing a new type of actions --- the deletion action. The resulted model is called lossy communicating finite state machines (LCFSMs). The LCFSM model remedies two weaknesses in classical CFSM model. We show that the LCFSM model allows specification and verification of unreliable communication channels with no need of extra CFSMs. The LCFSM model enables more succinct specification and verification of communication protocols that use unreliable communication channels. LCFSM paradigm can also be used to concisely model communication errors such as dropping datagrams in UDP due to lack of local buffers.","Title: A modular methodology to verify communication protocols\nYear: 1997\n\nAbstract: State explosion has been a major problem for verifying communication protocols and distributed algorithms. In this paper we analyze the sources that cause the state explosion problem and propose a modular approach to verifying communication protocols based on networks of communicating finite state machines (CFSMs). Our proposed method is innovative and its time and space complexity is independent of the number of processes in a system. The new methodology can significantly reduce the time and space needed to verify a number of interesting logical properties, as evidenced by our implementations.","Title: Automatic detection of errors in distributed systems\nYear: 1995\n\nAbstract: Debugging in a distributed environment is very complex when compared to debugging in a uniprocessor or sequential environment. The order of events in a distributed environment is not deterministic, and this order of events may some times produce some unexpected errors. These errors which depend on the timing of events are typical of distributed systems. In this paper we proposed an approach based on the timing graphs concept to debug these timing errors. Here we give some conditions which should be satisfied by a timing graph, if the execution of that instance of the program, from which the graph is constructed, doesn’t have any errors. The graphs are constructed using the information gathered at the run time using tracing mechanism. This approach uses topological sorting of directed acyclic graphs in analyzing the timing graphs. In this paper, we have developed the theory behind this approach and presented an algorithm to automate the procedure. Since the manual approach to this problem is cumbersome and error prone, this automatic error detection procedure simplifies the detection of the cause of the error for some standard error patterns.","Title: Achieving Flow Level Constant Performance Guarantees for CICQ Switches without Speedup\nYear: 2010\n\nAbstract: Performance guarantees provided by switches can be at different granularity: port level and flow level. As a trade-off, it is usually more expensive to provide performance guarantees at finer granularity. Existing solutions for switches to provide flow level performance guarantees require either expensive hardware support or centralized scheduling algorithms with multiple iterations. In this paper, we present the Flow-level Fair Scheduling (FFS) algorithm to provide flow level performance guarantees for Combined-Input- Crosspoint-Queued (CICQ) switches, which are special crossbar switches with a small exclusive buffer at each crosspoint of the crossbar. FFS uses hierarchical and multidimensional fair queueing to emulate the ideal Generalized Processing Sharing (GPS) model. The main features of FFS include: constant performance guarantees, bounded crosspoint buffer sizes, no speedup requirement, and distributed operation. We theoretically analyze the performance of FFS, and conduct simulations to verify the analytical results.","Title: Belief based data cleaning for wireless sensor networks\nYear: 2012\n\nAbstract: Wireless sensor network (WSN) data is often subjected to corruption and losses due to wireless medium of communication and presence of hardware inaccuracies in the nodes. For a WSN application to deduce an appropriate result it is necessary that the data received is clean, accurate, and lossless. WSN data cleaning systems exploit contextual associations existing in the received data to suppress data inconsistencies and anomalies. In this work we attempt to clean the data gathered from WSN by capturing the influence of changing dynamics of the environment on the contextual associations existing in the sensor nodes. Specifically, our work validates the extent of similarities among the sensed observations from contextually (spatio-temporally) associated nodes and considers the time of arrival of data at the sink to educate the cleaning process about the WSN's behavior. We term the data cleaning technique proposed in this work as time of arrival for data cleaning (TOAD). TOAD establishes belief on spatially related nodes to identify potential nodes that can contribute to data cleaning. By using information theory concepts and experiments on data sets from a real-time scenario we demonstrate and establish that validation of contextual associations among the sensor nodes significantly contributes to data cleaning. Copyright © 2010 John Wiley & Sons, Ltd.","Title: On Quality Of Service Routing in Ad-Hoc Networks\nYear: 2003\n\nAbstract: Ad-hoc networks can be formally defined as acollection of wireless mobile hosts dynamically forminga temporary network without the aid of any existingestablished infrastructure or centralized admission[1].The main focus of the paper is the extension to the QoSrouting procedure, which can inform the source qualityof service available to any destination in the wirelessnetwork. The Ad-Hoc On Demand Distance VectorRouting Protocol (AODV) is taken into considerationand an extension to the protocol has been suggested tosupport Quality of Service.","Title: Efficient solutions to multicast routing in communication networks\nYear: 1996\n\nAbstract: An important problemin both wireless and wired communication networks is to be able to efficiently multicast information to a group of network sites. Multicasting reduces the transmission overhead of both wireless and wired networks and the time it takes for all the nodes in the subset to receive the information. Since transmission bandwidth is a scarce commodity especially in wireless networks, efficient and near minimum-cost multicast algorithms are particularly useful in the wireless context. In this paper, we discuss methods of establishing efficient and near minimum-cost multicast routing in communication networks. In particular, we discuss an efficient implementation of a widely used multicast routing method which can construct a multicast tree with a cost no greater than twice the cost of an optimal tree. We also present two efficient multicast tree constructions for a general version of the multicast routing problem in which a network consists of different classes of nodes, where each class can have one or more nodes of the same characteristic which is different fromthe characteristics of nodes fromother classes. Because of their efficient running times, these multicast routing methods are particularly useful in the mobile communication environments where topology changes will imply recomputation of the multicast trees. Furthermore, the proposed efficient and near minimum-cost multicast routing methods are particularly suited to the wireless communication environments, where transmission bandwidth is more scarce than wired communication environments.","Title: A future location-aware replacement policy for the cache management at the mobile terminal\nYear: 2009\n\nAbstract: While the traditional data shipping systems use physical information to organize data, a newer data caching technique maintains both associated answers (data items) of previous queries and their meaning (purpose). This form of information description is called semantic description, and it makes it possible to reason about and derive knowledge from the given description. In a distributed heterogeneous environment, such as the mobile environment, the semantic data caching paradigm is an important technique for improving the performance of wireless data dissemination systems. Data caching performance depends heavily on the replacement policy being used for the cache management. However, future location uncertainty, limited client resources and frequent client disconnections make cache management a challenge. This paper proposes a future location-aware cache replacement policy to manage a semantic cache. The proposed replacement policy uses the validity of the data fetched from the server and the neighboring locations to decide which of the cache entries is less likely to be needed in the future, and therefore a good victim for eviction when cache space is needed. The replacement policy's preference for cached items to be evicted is modeled as a general function that declines with distance between the mobile user's current location and the candidate for replacement cached item's bound location. For better efficiency, the overall replacement granularity is dynamically achieved along three levels: ring, cell and data item. Simulation study of the proposed approach shows that it outperforms both the least recently used (LRU) and furthest away replacement (FAR) schemes, where only temporal locality is considered. Moreover, the proposed scheme is easier to implement than other research and development proposals. Copyright © 2008 John Wiley & Sons, Ltd.","Title: A proactive secure routing algorithm defense against node compromise in sensor networks\nYear: 2008\n\nAbstract: Providing a secure routing algorithm that defend against node compromise is a challenging task in sensor networks. In this paper, we propose a proactive secure routing algorithm (PSR) to conquer the undetected compromised nodes-the compromised nodes that the system has not detected them yet. Compared with other secure routing algorithms or ideas, routing paths in PSR not only bypass the detected compromised nodes but also bypass the nodes with larger probabilities of being compromised. To estimate the probability of node compromise, we introduce a node compromise distribution model. Simulations show that PSR is effective to prevent routing path from passing compromised nodes whether detected or not.","Title: A parallel algorithm for the Steiner tree problem\nYear: 1993\n\nAbstract: The Steiner problem in graphs is to find the minimum cost tree which spans at least a given subset of V, where V is the set of vertices in the graph. This problem has a wide variety of practical applications, including wire routing in physical VLSI design. Since the problem is NP-complete, much work has been devoted to developing approximate solutions such as the one proposed by V.J. Rayward-Smith (1988). In this paper, we identify the Rayward-Smith's algorithm as being appropriate for parallelization, and describe a parallel implementation of that algorithm. We also show that linear speedup is achievable on the PRAM model with the number of processors p⩽|V|","Title: Performance Analysis Of Dsr Using Cached Route Replies For Multihop Wireless Networks\nYear: 2005\n\nAbstract: Effective routing in multihop wireless networks is an interesting problem to solve because of the nature of multihop wireless networks. We use the DSR as an example of on demand routing protocol for multihop wireless networks to show the effectiveness of cache-enabled scheme. We present the performance evaluation of the enhanced routing scheme of using cached route replies for the DSR. Through simulation analysis, we demonstrate the effectiveness of this scheme in an on-demand (reactive) routing protocol. We collect the different performance statistics and show through simulation results that the performance is improved in terms of total traffic, routing traffic (overhead), and route discovery time and download response time. We have used OPNET modeler for simulating our scheme for multihop wireless network.","Title: Video Content Representation Based on Texture and Lighting\nYear: 2000\n\nAbstract: When dealing with yet unprocessed video, structuring and extracting features according to models that reflect the idiosyncrasies of a video data category (film, news, etc.) are essential for guaranteeing the content annotation, and thus the use of video. In this paper, we present methods for automatic extraction of texture and lighting features of representative frames of video data shots. These features are the most important elements which characterize the development of plastic (physical) space in the film video. They are also important in other video categories. Texture and lighting are two basic properties, or features, of video frames represented in the general film model presented in [12]. This model is informed by the internal components and interrelationships known and used in the film application domain. The method for extraction of texture granularity is based on the approach for measuring the granularity as the spatial rate of change of the image intensity [3], where we extend it to color textures. The method for extraction of lighting feature is based on the approach of closed solution schemes [4], which we improve by making it more general and more effective.","Title: Mobile users in heterogeneous environments with middleware platform\nYear: 2003\n\nAbstract: Mobile computing is becoming more and more pervasive, liberating users from the confines of wired networks. At the same time, transparent access to heterogeneous, distributed information sources has become a reality in wired computing. Obviously, this kind of access is highly desirable for mobile users, too. However, current architectures for transparent information access do not take the specific needs of mobile users into account, while existing architectures for mobile computing do not support transparent access well. For the future growth of the usage of mobile computing it is of utmost importance that instead of individually developed, isolated extensions to the existing architectures, the research community agrees on a strong, standardized middleware platform extending both existing mobile architectures and existing information access architectures to ensure mobile access in heterogeneous environments. In this paper we propose such a platform.","Title: Thermal aware clock synthesis considering stochastic variation and correlations\nYear: 2008\n\nAbstract: In this paper, we have proposed a thermal aware routing based parameterization to generate a clock model that takes the stochastic temperature variation into consideration. The worst-case skew is calculated by using the transient analysis. The proposed Thermal Aware Routing based Clock Tree Optimization (TARCO) is performed level by level via the use of sensitivities from the proposed macromodel. The experimental results show that our algorithm reduces up to 5X worst-case skew in comparison to the existing bonded-skew based Deferred Merge Embedding (DME) approach, and 1.7X worst-case skew compared to Perturbation based Clock Optimization (PECO) and 2.1X compared to Temperature Aware Clocktree Optimization (TACO).","Title: On Peer-To-Peer Location Management In Vehicular Ad Hoc Networks\nYear: 2009\n\nAbstract: Vehicular ad-hoc networks (VANETs) have been gained importance for the inter-vehicle communication that supports local communication between vehicles without any expensive infrastructure and considerable configuration efforts. How to provide light-weight and scalable location management service which facilitates geographic routing in VANETs remains a fundamental issue. In this paper we will present a novel peer-to-peer location management protocol, called PLM, to provide location management service in VANETs. PLM makes use of high mobility in VANETs to disseminate vehicles' historical location information over the network. A vehicle is able to predict current location of other vehicles with Kalman filtering technique. Our theoretical analysis shows that PLM is able to achieve high location information availability with a low protocol overhead and latency. The simulation results indicate that PLM can provide fairly accurate location information with quite low communication overhead in VANETs.. [Article copies are available for purchase from InfoSci-on-Demand.com]","Title: Self-organized forensic support in MANETs\nYear: 2008\n\nAbstract: A distributed hash table (DHT) based approach for supporting forensic capability in mobile ad hoc networks (MANETs) is presented. The DHT-based approach has been modified to inhibit recursive increase in bandwidth consumption due to forensic activity - the process of logging is associated with that of packet delivery via customizable decreasing functions. Simulation has revealed that this approach limits the bandwidth requirement for forensic activities, although it requires a trade-off between bandwidth consumption and effective logging. The focus is to design a self-organized logging system over networks with dynamic topology.","Title: A Real-Time Wireless Route Guidance System for Urban Traffic Management and Its Performance Evaluation\nYear: 2009\n\nAbstract: Selecting optimal routes to reduce travel time has been an important research area for urban traffic network managements. Various parameters such as route length, average speed and event situations need to be considered in the design of a route guidance system. In this paper, we develop a new navigation system based on the combination of fastest path search algorithm and travel time prediction method for urban traffic areas. Compared with previous route guidance systems, the results reveal that our system, applying the prediction based realtime fastest path (PRFP) algorithm, can significantly reduce the travel time especially when customers travel in a complex route environment and face frequent congestion. We also demonstrate the advantages of this system and verify the results using simulation.","Title: Dynamic key management for secure routing in MANET\nYear: 2007\n\nAbstract: A secure key management scheme for the locality caching multi-root multi-generation (LCMRMG) MANET routing algorithm is proposed. The scheme takes advantage of the multi-root nature of LCMRMG and successfully integrates public key, certification and threshold technologies. The scheme is hierarchical and fully distributed. The key management operations are flexible in secure share distribution and scalable well to large MANET. Extensive simulations have shown that the scheme is secure, robust, efficient, and scalable. Copyright (C) 2007 John Wiley & Sons, Ltd.","Title: A New Network Topology Evolution Generator Based on Traffic Increase and Distribution Model\nYear: 2007\n\nAbstract: Following traffic increase near to network backbone capacity in a domain network, the evolution of backbone topology takes place. In this paper, three main types of evolution methods: link upgrading only method (upgrade link capacity only), node upgrading method (add nodes and links with the same link capacity), and the combinations of previous two are explored. To shunt the saturated traffic efficiently, we propose several node upgrading generators - Adapting Traffic Evolution Topology gEnerators (ATETEs). ATETEs consider traffic distribution and node burden conditions and select the congested link as the main shunting object. The difference among ATETEs lies that they have diverse strategies to choose a node in the congested link as the second shunting aim. Simulation shows that: the type of ATETEs which picks the burdened node in the saturated link as another shunting object has the most effective shunting result. Compare with most of current topology generators such as [BRITE] in [1] which consider little about traffic increase distribution, ATETEs are more efficient to satisfy traffic increase.","Title: Spatio-Temporal Modeling in Video and Multimedia Geographic Information Systems\nYear: 2001\n\nAbstract: The geographic application domain includes important information such as design plans, record drawings, photographs, and video data records. The corresponding geographic information systems (GISs) should maintain a specific model for each geographic data modality such as geographic video model for video records. Real-time 3-D geographic information systems provide comprehensive interface to complex and dynamic databases and truly immersive capability for visualizing geographic data. In cases, where information about location of geographic objects is needed at different moments of time, a GIS should process video data that is directly manipulated and retrieved through representation of its spatio-temporal characteristics. In this context, the most advanced multimedia form—digital video, finds an efficient application in GIS for versatile specification of geographic data. In this paper, a model for spatial data evolving with time is introduced in the context of video data manipulation. We designed a model that represents the spatio-temporal continuum among geographic objects in geographic video sequences, or digital video. The model developed here was motivated by the requirements for manipulating, managing, and analyzing geographic data for the necessities of infrastructure management, urban and regional planning, hazard prevention and management, transportation networks, vehicles routing, etc. This model allows the important issues for GIS such as conditions of adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close one geographic object is to another) to be determined. Our model describes the spatial relationships among objects for each key frame in a given video scene, and the temporal relationships of the temporal intervals measuring the validity duration of the spatial relationships spanning over the given key frame. One of the main GIS issues—distance estimation, is solved as quantitative metrics of geographic objects in digital video are easily and precisely specified. This model is a basis for annotation of raw video for subsequent use in geographic video databases and digital libraries that provide access to and efficient storage of large volume of geographic data.","Title: The Steiner tree problem with minimum number of vertices in graphs\nYear: 1992\n\nAbstract: The Steiner tree problem is to find a tree in a connected undirected distance graph G=(V, E, d) which spans a given set S⊆V. The minimum Steiner tree for G and S is a tree which spans S with a minimum total distance on its edges. The authors consider a special case of the Steiner tree problem in graphs. For this problem they assume that the underlying graph G does not have any direct edge between the vertices in S⊆V. The problem is to find a tree in G which spans the vertices in S and uses minimum number of vertices in V-S","Title: Locality caching multiroot multigeneration routing algorithm in mobile ad hoc networks\nYear: 2003\n\nAbstract: A locality caching multiroot multigeneration (LCMRMG) routing algorithm for mobile ad hoc networks (MANET). The LCMRMG algorithm extends and significantly enhances a previously proposed single-root MANET routing algorithm. Hosts in a LCMRMG MANET cache the locality of network traffic routing through them. Based on the cached locality statistics, a host can calculate the estimated reduction of network traffic if it becomes a new root router and can elect to do so if the reduction exceeds a predefined threshold value.","Title: Spatio-temporal composition of video objects: representation and querying in video database systems\nYear: 2001\n\nAbstract: A key characteristic of video data is the associated spatial and temporal semantics. It is important that a video model models the characteristics of objects and their relationships in time and space. J.F. Allen's (1983) 13 temporal relationships are often used in formulating queries that contain the temporal relationships among video frames. For the spatial relationships, most of the approaches are based on projecting objects on a two or three-dimensional coordinate system. However, very few attempts have been made formally to represent the spatio-temporal relationships of objects contained in the video data and to formulate queries with spatio-temporal constraints. The purpose of the work is to design a model representation for the specification of the spatio-temporal relationships among objects in video sequences. The model describes the spatial relationships among objects for each frame in a given video scene and the temporal relationships (for this frame) of the temporal intervals measuring the duration of these spatial relationships. It also models the temporal composition of an object, which reflects the evolution of object's spatial relationships over the subsequent frames in the video scene and in the entire video sequence. Our model representation also provides an effective and expressive way for the complete and precise specification of distances among objects in digital video. This model is a basis for the annotation of raw video","Title: Belief-free equilibrium of packet forwarding game in ad hoc networks under imperfect monitoring\nYear: 2010\n\nAbstract: Future applications will require autonomous devices to be interconnected and form ad hoc networks. In such networks, cooperation will be the first problem to solve at all layers of the protocol stack. This paper deals with one of the basic functions of a network, namely packet forwarding. We model packet forwarding as a stochastic game in which each node monitors the behavior of its neighbors. We consider the realistic scenario when the monitoring technology used by the nodes is imperfect. In reality, there can be inconsistencies between the true action of a node and the observations of its neighbors. Therefore, in an ad hoc network, each node receives only noisy private information about the past play of its neighbors. We develop a simple one period memory strategy that constrains self-interested nodes to cooperate under noise. We use a belief-free approach. A belief-free approach delivers a tremendous computational advantage because nodes' belief about the neighbors' private history does not need to be computed. We support our results by mathematical proofs and simulations.","Title: Game Theoretic Modeling and Evolution of Trust in Autonomous Multi-Hop Networks: Application to Network Security and Privacy\nYear: 2011\n\nAbstract: Future applications will require autonomous devices to be interconnected to form a network. Such networks will not have a central manager; each node will manage itself and will be free to decide participation in any network function. As with traditional networks, these networks need to be secured to authenticate the nodes, prevent misuse, detect anomalies and protect user privacy. Network security and privacy protection without a central manager will be challenging. Several security mechanisms and privacy protections will require the cooperation of several nodes to defend the network from malicious attacks. We particularly investigate when for each node it is cost-effective to freely participate in the security mechanism or protect its privacy depending if that node believes or trusts that all other nodes or at least a minimum number of other nodes will do the same. In this case, each node will be involved in a trust dilemma that we will model using the mathematical framework of game theory and evolutionary game theory. The well known stag hunt game will be our basic game model. This paper will clearly present the interconnection between cooperation, trust, privacy and security in a network.","Title: Mobile learning object authoring tool and management system for mobile ad hoc wireless networks\nYear: 2015\n\nAbstract: Mobile learning can augment formal education and bridge the gap between formal and informal education by creating extended learning communities using any digital technology in connected or infrastructure-less environments. With the use of ad hoc networks and mobile authoring tools, we can now create an 'on-the-fly' learning scenario, where learners can create, share, and view content from their mobile devices without the need for server-client or infrastructure-based liaisons. Mobile learning, however, is not just about sharing content or learning using mobile, wireless, and portable devices. Rather, it is learning across spatiotemporal contexts that enables learners to form knowledge and understanding in different scenarios. When facing limited resources stemming from the characteristics of mobility and wireless technologies, determining the best practices for content creation and delivery becomes a challenge. This paper describes the architecture of a mobile-focused learning network designed so that learning tools, activities, contexts, and interactions are created as necessary over time and space while adhering to traditional learning object standards. Copyright © 2015John Wiley & Sons, Ltd.","Title: Game theoretic modeling of security and trust relationship in cyberspace\nYear: 2016\n\nAbstract: AbstractToday, online network services have evolved as the highest-emergent medium, enabling various online activities to be lucrative. However, these lucrative activities also bring new forms of privacy threats to the community. In a reliable e-business service, users should be able to trust the providers of the service to protect their customers' privacy. The service providers should not risk the personal and private information about their customers in cyberspace. There is an economic gain for a business provider when users trust the service provider. Despite those benefits, cyber security concern is the main reason some large organization may go bankrupted. Unfortunately, attackers may attempt to breach a provider's database and expose customers' private information. Therefore, in this paper, we propose a game theoretic framework for security and trust relationship in cyberspace for users, service providers, and attackers. Mathematical proofs and evaluations support our model. Service providers may use the model to see how important and dissuasive against attackers is when investing in cybersecurity. Copyright © 2016 John Wiley & Sons, Ltd.","Title: A Game-Theoretic Approach On Resource Allocation With Colluding Nodes In Manets\nYear: 2016\n\nAbstract: Prevalent concerns with dynamic networks typically involve security. Especially with resource constraints in dynamic networks such as mobile ad-hoc networks (MANETs), security needs to be of particular consideration. In this paper, we first analyze the solution concept involved in optimizing resource allocation and data packet forwarding. In a MANET, the availability of having data packets forwarded may be insubstantial due to the presence of selfish nodes. Nodes may not want to participate in the network to preserve their own resources. We propose a packet-forwarding problem model with a negotiation game, where an arbitrator acts as a cluster head and initiates a bargaining game. Thereafter, we consider the possibility of having some group of nodes exhibit malicious behavior and collude to subvert the MANET. We investigate the problem by finding the optimal Nash Equilibrium (NE) strategies of the negotiation game. Then, we simulate the effect of the coalition of malicious nodes in a mobile environment. Simulation results support our model.","Title: Game theoretic analysis for resource allocation in dynamic multi-hop networks with arbitration\nYear: 2017\n\nAbstract: A connection through a mobile node may not be available because of the greediness of selfish nodes. In this paper, we address the issue of dynamic packet forwarding by a set of wireless autonomous ad hoc nodes. Wireless nodes acting in a selfish manner try to use the resources of other nodes without their own participation. We model the dynamic packet forwarding problem as a negotiation game with an arbitrator. In our model, a group of mobile nodes requesting to forward packets negotiates with a mobile arbitrator until an agreement at least by simple majority is reached on a resource allocation. The mobile arbitrator submits offers to each mobile device in the group, and the mobile nodes decide to agree or disagree on the offer. The ultimate decision is made by simple majority. We investigate and solve the negotiation by finding the optimal Nash Equilibrium strategies of the game. We consider offers generated from Dirichlet's distribution for an ensemble of mobile devices over a finite and sporadic time limitation. The solution obtained from negotiation ensures that a mobile device always finds a peer or arbitrator to help forward packets and keep the network flowing. Mathematical proofs and MATLAB simulations support our model."],"string":"[\n \"Title: A context-aware prefetching strategy for mobile computing environments\\nYear: 2006\\n\\nAbstract: In a mobile wireless environment, the latency (time-delay) observed by a user before s/he receives up-to-date information may be high because of the limited available bandwidth. An efficient prefetching strategy must be tailored to the competing goals of keeping latency low (which requires more prefetching) and reducing resource waste in a mobile environment, which is characterized by scarce bandwidth and resource-poor user devices. Current research is based on the tangent velocity approach, which is effective only within a short time interval and has a high cost of continuous geometric estimations.This paper proposes a cache management method that maintains the mobile terminal's cache content by prefetching data items with maximum benefit and evicting cache data entries with minimum benefit. The data item benefit is evaluated based on the user's query context defined as a set of constraints (predicates), which define both the movement pattern and information context requested by the mobile user. A context-aware cache is formed and maintained using a set of neighboring locations (we call the prime list) restricted by the validity of the data fetched from the server. Simulation results show that the proposed strategy using different levels of granularity can greatly improve the system performance in terms of cache hit ratio.\",\n \"Title: Machine Learning On Congestion Analysis Based Real-Time Navigation System\\nYear: 2011\\n\\nAbstract: In the metropolitan region, most congestion or traffic jams are caused by the uneven distribution of traffic flow that creates bottleneck points where the traffic volume exceeds the road capacity. Additionally, unexpected incidents are the next most probable cause of these bottleneck regions. Moreover, most drivers are driving based on their empirical experience without awareness of real-time traffic situations. This unintelligent traffic behavior can make the congestion problem worse. Prediction based route guidance systems show great improvements in solving the inefficient diversion strategy problem by estimating future travel time when calculating accurate travel time is difficult. However, performances of machine learning based prediction models that are based on the historical data set degrade sharply during a congestion situation. This paper develops a new navigation system for reducing travel time of an individual driver and distributing the flow of urban traffic efficiently in order to reduce the occurrence of congestion. Compared with previous route guidance systems, the results reveal that our system, applying the advanced multi-lane prediction based real-time fastest path (AMPRFP) algorithm, can significantly reduce the travel time especially when drivers travel in a complex route environment and face frequent congestion problems. Unlike the previous system,(1) it can be applied either for single lane or multi-lane urban traffic networks where the reason for congestion is significantly complex. We also demonstrate the advantages of this system and verify the results using real highway traffic data and a synthetic experiment.\",\n \"Title: Ensemble Of Machine Learning Algorithms For Intrusion Detection\\nYear: 2009\\n\\nAbstract: Ensemble-classifier is a technique that uses a combination of multiple classifiers to reach a more precise inference result than a single classifier. In this paper, a three-layer hierarchy multi-classifier intrusion detection architecture is proposed to promote the overall detection accuracy. For making every individual classifier is independent from others, each uses a diverse soft computing technique as well as different feature subset. In addition, the performances of a variety of combination methods that fuse the outputs from classifiers are studied. In the experiments, DARPA KDD99 intrusion detection data set is chosen as the evaluation tools. The results show that our approach achieves a better performance than that of a single classifier.\",\n \"Title: Design And Evaluation Of An Efficient Traffic Control Scheme For Integrated Voice, Video, And Data Over Asynchronous Transfer Mode Networks: Explicit Allowed Rate Algorithm\\nYear: 1999\\n\\nAbstract: Asychronous transfer mode (ATM) networks are high-speed networks with guaranteed quality of service. The main cause of congestion in ATM networks is over utilization of physical bandwidth. Unlike constant bit-rate (CBR) traffic, the bandwidth reserved by variable bit-rate (VBR) traffic is not fully utilized at all instances. Hence, this unused bandwidth is allocated to available bit-rate (ABR) traffic. As the bandwidth used by VER traffic changes, available bandwidth for ABR traffic varies; i.e., available bandwidth for ABR traffic is inversely proportional to the bandwidth used by the VER traffic. Based on this fact, a rate-based congestion control algorithm, Explicit Allowed Rate Algorithm (EARA), is presented in this paper. EARA is compared with Proportional Rate Control Algorithm (PRCA) and Explicit Rate Indication Congestion Avoidance Algorithm (ERICA), in both LAN and WAN environments. Simulation of all three algorithms are conducted under both congestion and fairness configurations with simultaneous generation of CBR, rt-VBR, nrt-VBR and ABR traffic. The results show that, with very small over-head on the switch, EARA significantly decreases the required buffer space and improves the network throughput. Copyright (C) 1999 John Wiley & Sons, Ltd.\",\n \"Title: A coherent architecture for a temporal object data base management system\\nYear: 1994\\n\\nAbstract: The last decade has witnessed the emergence of practical general-purpose data base management systems (DBMS) as “state of the art” technology. In consequence, these systems are now widely used in a variety of application environments. However, many such systems were designed to capture current data, i.e., a snapshot of reality, but are insufficient for those applications in which past or future data are also required. Even so, there has been little effort to design temporal DBMS, and currently there are no prominent commercial temporal DBMS. This article identifies, explores, and provides an approach to designing a coherent architecture for a temporal object DBMS (TODBMS). It specifically involves the design, development, and implementation of TODBMS. We introduce the basic features of our system and provide an overview of the functionalities supported. In addition, we identify the major components of TODBMS and define the types of services each component should offer, as well as common abstractions and interfaces for these components. Application environments include management and geographic information systems, data base visualization, and robotics.\",\n \"Title: Using logical rings to solve the distributed mutual exclusion problem with fault tolerance issues\\nYear: 2000\\n\\nAbstract: In this paper, we investigate distributed mutual exclusion algorithms and delineate the features of a new distributed mutual exclusion algorithm. The basis of the algorithm is the logical ring structure employed in token-based mutual exclusion algorithms. Specifically, there exists dynamic properties of the logical ring that, given certain restrictions regarding message traffic flow, passively give useful information about the location of the token. Effectively, the algorithm demonstrates a type of 'intelligent routing' that identifies useful shortcuts in the routing of the token. The result is a reduction in the total number of messages exchanged prior to the execution of the critical section as compared to the algorithm proposed by Fu and Tzeng [3]. Furthermore, the algorithm allows for an increased degree of fairness in a lightly loaded system than that allowed by Fu and Tzeng's algorithm. The paper also addresses failure recovery issues.\",\n \"Title: Resource Management In The Next-Generation Integrated Wlan/3g Cellular Networks\\nYear: 2007\\n\\nAbstract: The next-generation (4G) wireless communication systems focus on the seamless integration of various existing wireless communication networks, such as integrating the third-generation (3G) cellular networks and wireless local area network (WLAN). Resource management (RM) is one of the essential techniques to improve both overall resource utilization and quality-of-service (QoS) provisioning. In this paper, we proposed a novel joint resource management scheme with QoS provisioning. A joint call admission policy is derived to support heterogeneous network architecture, service types, user mobility characteristics, and QoS levels. To relieve traffic congestion, an optimal channel searching and replacement algorithm (oCSR) and passive handoff techniques are further developed to balance total system traffic between WLAN and 3G cellular network as well as to reduce average system QoS cost, such as weighted blocking probability. Theoretical analysis and simulation results show that our scheme outperforms both traditional disjoint RM and joint RM without optimization.\",\n \"Title: Achieve constant performance guarantees using asynchronous crossbar scheduling without speedup\\nYear: 2010\\n\\nAbstract: Buffered crossbar switches are special crossbar switches with a small exclusive buffer at each crosspoint of the crossbar. They demonstrate unique advantages, such as variable length packet handling and distributed scheduling, over traditional unbuffered crossbar switches. The current main approach for buffered crossbar switches to provide performance guarantees is to emulate push-in-first-out output queued switches. However, such an approach has several drawbacks, and in particular it has difficulty in providing tight constant performance guarantees. To address the issue, we propose in this paper the guaranteed-performance asynchronous packet scheduling (GAPS) algorithm for buffered crossbar switches. GAPS intends to provide tight performance guarantees, and requires no speedup. It directly handles variable length packets without segmentation and reassembly, and makes scheduling decisions in a distributed manner. We show by theoretical analysis that GAPS achieves constant performance guarantees. We also prove that GAPS has a bounded crosspoint buffer size of 3L, where L is the maximum packet length. Finally, we present simulation data to verify the analytical results and show the effectiveness of GAPS.\",\n \"Title: Towards a framework for integrating multilevel secure models and temporal data models\\nYear: 1994\\n\\nAbstract: Within many organizations the number of databases containing classified or otherwise sensitive data is increasing rapidly. Access to these databases must be restricted and controlled to limit the unauthorized disclosure, or malicious modification of data contained in them. However, the conventional models of authorization that have been designed for database systems supporting the hierarchical, network and relational models of data do not provide adequate mechanisms to support controlled access of temporal objects and context based temporal information. In this paper we extend the multilevel secure relational model to capture the functionality required of a temporal database, i.e. a database that supports some aspect of time, not counting user-defined time. In particular we assign class access to bitemporal timestamped attributes, and give explicit security classifications to temporal elements.\",\n \"Title: A Framework for Temporal Object Databases\\nYear: 1992\\n\\nAbstract: The 3 Dimensional Information Space (3DIS) is a rich, extensible, object database model for information management. Here, we concentrate on extending the 3DIS to incorporate the semantics of time, and to support temporal data and the temporal evolution of data. We present a unique approach towards the synthesis of an integrated 3DIS model that supports the temporal aspects of data modeling in addition to the structural and dynamic ones, while preserving its original three dimensional geometric space features. This research presents a step towards defining the concepts and techniques for incorporating time in object databases, and provides a concrete experimental framework for demonstration thereof.\",\n \"Title: MURU: A Multi-Hop Routing Protocol for Urban Vehicular Ad Hoc Networks\\nYear: 2006\\n\\nAbstract: Vehicular ad hoc networks (VANETs) are going to be an important communication infrastructure in our life. Because of high mobility and frequent link disconnection, it becomes quite challenging to establish a robust multi-hop path that helps packet delivery from the source to the destination. This paper presents a multi-hop routing protocol, called MURU that is able to find robust paths in urban VANETs to achieve high end-to-end packet delivery ratio with low overhead. MURU tries to minimize the probability of path breakage by exploiting mobility information of each vehicle in VANETs. A new metric called expected disconnection degree (EDD) is used to select the most robust path from the source to the destination. MURU is fully distributed and does not incur much overhead, which makes MURU highly scalable for VANETs. The design is sufficiently justified through theoretical analysis and the protocol is evaluated with extensive simulations. Simulation results demonstrate that MURU significantly outperforms existing ad hoc routing protocols in terms of packet delivery ratio, packet delay and control overhead\",\n \"Title: An Efficient Approximate Algorithm For Delay-Cost-Constrained Qos Routing\\nYear: 2001\\n\\nAbstract: The problem of finding a path with two additive constraints is called multi-constrained path (MCP) problem in the literature. In this paper, we explore the MCP problem based on the idea of single mixed weight. Given two infeasible paths, it can be theoretically proved that a better path can possibly be found if we choose an appropriate parameter to construct the mixed weight. An approximate algorithm is thus proposed to solve the MCP problem. A large number of experiments on networks of different sizes demonstrate that this algorithm can make a correct judgment whether there is a feasible path or not with a very high probability. On the other band, the time complexity of this algorithm is very small since it only needs to execute Dijkstra's algorithm a limited number of times even for a network of relatively large size.\",\n \"Title: Providing Performance Guarantees for Buffered Crossbar Switches without Speedup\\nYear: 2009\\n\\nAbstract: Buffered crossbar switches are special crossbar switches with each crosspoint equipped with a small exclusive buffer. The crosspoint buffers decouple input ports and output ports, and simplify switch scheduling. In this paper, we propose a scheduling algorithm called Fair and Localized Asynchronous Packet Scheduling (FLAPS) for buffered crossbar switches, to provide tight performance guarantees. FLAPS needs no speedup for the crossbar and handles variable length packets without segmentation and reassembly (SAR.). With FLAPS, each input port and output port independently make scheduling decisions and rely on only local queue statuses. We theoretically show that a crosspoint buffer size of 4L is sufficient for FLAPS to avoid buffer overflow, where L is the maximum packet length. In addition, we prove that FLAPS achieves strong stability, and provides bounded delay guarantees. Finally, we present simulation data to verify the analytical results.\",\n \"Title: Fuzzy Belief Reasoning for Intrusion Detection Design\\nYear: 2007\\n\\nAbstract: In this paper, we propose a method to resolve uncertainty problems by incorporating fuzzy clustering technique and Dempster-Shafer theory. Also, the k- nearest neighbors (k-NN) technique is applied to speed up the detection process and C4.5 decision tree algorithm is used to improve the classification accuracy. For verifying the performance of our classifier, DARPA KDD99 Intrusion Detection Evaluation data set is used. We compare the results of our proposed approach with those of k-NN classifier, fuzzy k-NN classifier and evidence-theoretic k-NN classifier. The result indicates that our approach has a better performance than these from the other three classifiers.\",\n \"Title: Communications via Systems-on-Chips Clustering in Large-Scaled Sensor Networks\\nYear: 2008\\n\\nAbstract: In this paper, we have proposed a framework of systems-on-chips clustering in application to complicated sensor networks. The framework can be applied to address the communication issues in distributed and large-scaled sensor nodes in wireless sensor network application. There are two communication categories under consideration, i.e. intra-nodes and inter-nodes. Due to the potentially higher frequency in the signal propagation within the sensor node, the characteristics of the interconnect among various systems-on-chips cannot be described in the traditionally lumped R, L, C components. We adapt a distributed transmission line model to address such issues and possibly improve the reliability in the intra-nodes communication. Furthermore, based on the bandwidth requirements of each sensor node, the large-scaled senor network is proposed to be transformed into a maze diagram by a user defined threshold bandwidth, so that many existing approaches may be applied to determine the routing paths in the inter-nodes communication to improve the efficiency of the overall network.\",\n \"Title: Collaborative Trust-Based Secure Routing in Multihop Ad Hoc Networks\\nYear: 2004\\n\\nAbstract: In this paper we have proposed a secure routing protocol based on AODV for multihop ad hoc networks. Our protocol is unique in the sense that it is capable of finding a secure end-to-end route free of any malicious entity, thus resisting an internal attack within the network either in the form of compromised or disloyal nodes. We propose to find a secure and efficient route to a destination based on collaborative effort of all the nodes.\",\n \"Title: A Future Location-Prediction Replacement Strategy For Mobile Computing Environments\\nYear: 2006\\n\\nAbstract: While the traditional data shipping systems use physical information to organize data, a newer data caching technique maintains both associated answers (data items) of previous queries and their meaning (purpose). This form of information description is called semantic description, and it makes it possible to reason about and derive knowledge from the given description. In a distributed heterogeneous environment, such as the mobile environment, the semantic data caching paradigm is an important technique for improving the performance of wireless data dissemination systems. Data caching performance depends heavily on the replacement policy being used for the cache management. However, future location ambiguity, limited client resources and frequent client disconnections make cache management a challenge.This paper proposes a future location-aware cache replacement policy to manage a semantic cache. The proposed replacement policy uses the validity of the data fetched from the server and the neighboring locations to decide which of the cache entries is less likely to be needed in the future, and therefore, a good candidate to be evicted when cache space is needed. The replacement policy's preference for cached items to be evicted is modelled as a general function that declines with distance between the cell the candidate for replacement's cached item is bounded to and the query's bound cell. For better efficiency the overall replacement granularity is dynamically achieved along three levels: ring, cell and data item. Simulation study of the proposed approach shows that it outperforms both the least recently used (LRU) and furthest away replacement (FAR) schemes, where only temporal locality is considered. Moreover, the proposed scheme is easier to implement than the industry standard policies.\",\n \"Title: The secure model for enterprise connectivity.\\nYear: 2000\\n\\nAbstract: The need for implementing data security over the enterprise network model has been brought to the forefront of the e-commerce marketplace by an increasing amount of incidents involving the compromise of confidential data as well as the abuse of private information by electronic intruders. The priority of data that is being stored, distributed and processed over the network medium has led to a strong focus on the security of the data, and the security of systems that contain and distribute it. The ideal of this new prototype is an alternative mode of enforcing security on enterprise networks by using algorithms aimed at data fragmentation rather than encryption. While encryption provides a means for scrambling data through the use of complex algorithms, this model proposes a mechanism for fragmenting the data stream in a way that reconstruction is possible only within a zone deemed safe by the implementation process. By binding the reconstruction process to a logical location within the safe area, it is possible to enforce a high level of safety around the entire data link process. The compromise of all data fragments would not allow reconstruction into the original form without the necessary complimentary reconstruction algorithm. As another layer of security, the reconstruction algorithm would allow execution only from a predefined logical location on the enterprise domain, and would thus be rendered useless if executed from an intruder's location. This system ensures that the overhead involved with imposing higher encryption strengths is bypassed without the loss of the security enforced over the system.\",\n \"Title: Estimated Replication Of Data In Wireless Sensor Networks\\nYear: 2008\\n\\nAbstract: A wireless sensor network (WSN) can be envisaged as a distributed system where the sensor nodes (clients) continuously update the sensed information to the sink (server). In many real-time environments exact replica of data is not required by the end application to deduce the result. Data estimation/prediction techniques at the sink can be used to infer the desired output. The proposed design is an improvement of the model as proposed by Santini [1] which uses the traditional LMS algorithm to predict the desired output at the sink. In this work we solve the synchronization of mode problem in the Santini's model by effectively utilizing the the principles of adaptive filter theory. The focus of this paper is to make better use of communication resources in data replication platforms than approaches based on periodic refreshing.\",\n \"Title: Waiting time of handoff calls for the wireless mobile networks with dependent calls arrival processes and impatient calls\\nYear: 2000\\n\\nAbstract: This paper studies the quasi-waiting time, the actual waiting time of the handoff calls in the buffer and the actual call holding times of new calls for the mobile wireless networks, in which the new calls arrival processes may depend on the number of calls in the target cells and the handoff calls arrival processes from the given cell to the target cell are modeled to be dependent on the number of calls in the given cells. In particular, the caller in the buffer waiting for further communication may become impatient. We propose an analytical model and obtain the expressions of the quasi and actual waiting time of a handoff call in the buffer, and prove that the actual call holding time of a new call is exponential. Some special cases of our model used in previous traffic models of wireless and/or wireline communications are discussed. The results presented in this paper may provide guidelines for field data processing on updated wireless mobile network design and performance evaluation\",\n \"Title: Reachability and reverse reachability analysis of CFSMs\\nYear: 1996\\n\\nAbstract: Reachability analysis and the recently proposed reverse reachability analysis are two important verification techniques for communicating finite state machines (CFSM). The issue of the relative efficiency of reachability analysis and reverse reachability analysis is still unsettled. In this paper, we first propose a new theory of reachability and reverse reachability analysis. Based on the new theory, we discuss and analyse the suitability of these two reachability analysis methods. We then present a reachability evaluator which, given any network of CFSMs, will try to estimate the sizes of the reachable and reverse reachable state spaces by taking snapshots of the reachability and reverse reachability spaces. The core of the evaluator is the notion of random state generation with seed states, which extends the idea of random state exploration proposed in [1]. Results from example applications have shown that the evaluator provides an excellent guidance in choosing the better of the two methods.\",\n \"Title: A token based distributed k mutual exclusion algorithm\\nYear: 1992\\n\\nAbstract: The authors present an algorithm for solving the k mutual exclusion problem in a distributed system. The algorithm is token based, whereby a token is passed among sites. Only sites that either receive the token with a nonzero semaphore or receive the token with a zero semaphore and later receive a release message from a previous site are allowed to enter their critical sections. Attached to the token is a queue which lists the sites scheduled to receive the token and a general semaphore. In all cases except extremely light token request traffic, the number of messages per critical section execution can be expressed as a small constant. This constant approaches three in an extremely heavy token request environment.\",\n \"Title: Efficient implementations of a delay-constrained least-cost multicast algorithm.\\nYear: 2002\\n\\nAbstract: Constrained minimum Steiner tree (CMST) problem is a key issue in multicast routing with quality of service (QoS) support. Bounded shortest path algorithm (BSMA) has been recognized as one of the best algorithms for the CMST problem due to its excellent cost performance. This algorithm starts with a minimum-delay tree, and then iteratively uses a k-shortest-path (KSP) algorithm to search for a better path to replace a \\\\superedge\\\" in the existing tree, and consequently reduces the cost of the tree. The ma- jor drawback of BSMA is its high time complexity because of the use of the KSP algorithm. For this reason, we investigate in this paper the possibility of more ecien t implementations of BSMA by using dieren t methods to locate the target path for replacing a superedge. Our experimental results indicate that our methods can signican tly reduce the time complexity of BSMA without deteriorating the cost performance.\",\n \"Title: On Petri nets and self-stabilization of communication protocols\\nYear: 1996\\n\\nAbstract: With Petri nets as the concurrent model, the issue of self-stabilizing communication protocols is discussed. It is argued that self-stabilizing extensions of communication protocols should not interfere with their normal operations by giving a new definition of self-stabilizing extension and a ring net that meets the new definition. It is also argued that communication protocols are usually delay sensitive and timed Petri nets provide a more suitable formal model than ordinary Petri nets to express the self-stabilizing property. The possibility and suitability of using Petri nets with a new type of transitions, the max transitions, to express self-stabilizing communication protocols is explored. To facilitate practical implementations, two types of interferences, external and internal interferences, are formally identified and discussed\",\n \"Title: Mobile Agents to Automate Fault Management in Wireless and Mobile Networks\\nYear: 2000\\n\\nAbstract: This paper studies the automation of fault management of wireless and mobile networks. A network management protocol similar to SNMP with an integrated architecture using mobile agents will prove effective in fault management of such networks. In view of the above, we design a wireless network management protocol to support fault management. In particular, we use mobile agents to detect, diagnose and recover from faults in wireless and mobile networks.\",\n \"Title: Inferring Internet Worm Temporal Characteristics\\nYear: 2008\\n\\nAbstract: Internet worm attacks pose a significant threat to network security. In this work, we coin the term Internet worm tomography as inferring the characteristics of Internet worms from the observations of Darknet or network telescopes that are routable but unused IP addresses. Under the framework of Internet worm tomography, we attempt to infer worm temporal behaviors such as the host infection time and the worm infection sequence, and thus pinpoint patient zero. Specifically, we introduce statistical estimation techniques and propose method of moments, maximum likelihood, and linear regression estimators. We show analytically and empirically that our proposed estimators can better infer worm temporal characteristics than a naive estimator that has been used in the previous work.\",\n \"Title: Fair Queueing Based Packet Scheduling for Buffered Crossbar Switches\\nYear: 2009\\n\\nAbstract: Recent development in VLSI technology makes it feasible to integrate on-chip memories to crossbar switching fabrics. Switches using such crossbars are called buffered crossbar switches, in which each crosspoint has a small exclusive buffer. The crosspoint buffers decouple input ports and output ports, and reduce the switch scheduling problem to the fair queueing problem. In this paper, we present the fair queueing based packet scheduling scheme for buffered crossbar switches, which requires no speedup and directly handles variable length packets without segmentation and reassembly (SAR). The presented scheme makes scheduling decisions in a distributed manner, and provides performance guarantees. Given the properties of the actual fair queueing algorithm used in the scheduling scheme, we calculate the crosspoint buffer size bound to avoid overflow, and analyze the fairness and delay guarantees provided by the scheduling scheme. In addition, we use WF2Q, the fair queueing algorithm with the tightest performance guarantees, as a case study, and present simulation data to verify the analytical results.\",\n \"Title: A context-aware cache structure for mobile computing environments\\nYear: 2007\\n\\nAbstract: This paper proposes a cache management method that maintains a mobile terminal's cache content by prefetching data items with maximum benefit and evicting cache data entries with minimum benefit. The data item benefit is evaluated based on the user's query context which is defined as a set of constraints (predicates) that define both the movement pattern and the information context requested by the mobile user. A context-aware cache is formed and maintained using a set of neighboring locations (called the prime list) that are restricted by the validity of the data fetched from the server. Simulation results show that the proposed strategy, using different levels of granularity, can greatly improve system performance in terms of the cache hit ratio.\",\n \"Title: An Agent-Based Mobile System\\nYear: 1997\\n\\nAbstract: In this paper we propose a new mobile system architecture, called the Client-Representative-Agent-Server (CRAS) architecture. While developing this architecture, an attempt is being made to keep GRAS compatible existing distributed object management frameworks and standards.\",\n \"Title: A Hybrid Method To Cellular Traffic Using Optic Beam Interconnects\\nYear: 2000\\n\\nAbstract: We propose a new type of wireless system, which is to provide for multimedia, bandwidth upon demand and Quality of Service (QoS) to the user. The system proposes to disable the problem caused by the unavailability of wired access by inculcating large bandwidths upon demand to individual users. The scheme proposes the use of optical beams in interconnecting mobile-telephone-switching-offices (MTSO) with each other using distinct WDM measures in a multihop scenario. Small microcells capable of growing themselves and reducing back to their macro size are employed. Traffic is dealt with the anomalous expansion and contraction of these cells. A high data rate to individual users is provided upon by a FH-CDMA based system whereby the chip rate becomes proportional to the channel quality. This ad-hoc method of adaptive coding helps the user maintain a uniform data rate through out all times.Benefits of this approach are dealt with in great detail and issues of reliability and hand off as well as system diversity is dealt with. As a further approach is suggested the interaction of this system with an all-optical underlaying network.\",\n \"Title: Attack distribution modeling and its applications in sensor network security\\nYear: 2008\\n\\nAbstract: Defending against attack is the key successful factor for sensor network security. There are many approaches that can be used to detect and defend against attacks, yet few are focused on modeling attack distribution. Knowing the distribution models of attacks can help system estimate the attack probability and thus defend against them effectively and efficiently. In this paper, we use probability theory to develop a basic uniform model, a basic gradient model, an intelligent uniform model and an intelligent gradient model of attack distribution in order to adapt to different application environments. These models allow systems to estimate the attack probability of each node under a given position and time. Applying these models in system security designs can improve system security performance and decrease the overheads in nearly every security area. Based on these models, we describe a novel probability secure routing algorithm that is effective to defend against attacks whether they are detected or not. Besides this application, we also introduce some other applications, such as secure routing that can save systems available energy and resources while still providing enough security, detecting attack, and key management.\",\n \"Title: A Middleware-Based Architecture to Support Transparent Data Access by Mobile Users in Heterogeneous Environments\\nYear: 2000\\n\\nAbstract: Mobile computing is becoming more and more pervasive, liberating users from the confines of wired networks. At the same time, transparent access to heterogeneous, distributed information sources has become a reality in wired computing. Obviously, this kind of access is highly desirable for mobile users, too. However, current architectures for transparent information access do not take the specific needs of mobile users into account, while existing architectures for mobile computing do not support transparent access well. For the future growth of the usage of mobile computing it is of utmost importance that instead of individually developed, isolated extensions to the existing architectures, the research community agrees on a strong, standardized middleware platform extending both existing mobile architectures and existing information access architectures to ensure mobile access in heterogeneous environments. In this paper we propose such a platform.\",\n \"Title: A new storage organization for temporal data bases\\nYear: 1994\\n\\nAbstract: A temporal data base needs to maintain large amounts of data, which causes long delays in accessing information. In this article, we design and develop an efficient storage structure for maintaining both current and historical data. Our strategy consists of two storage organizations, one for current versions and the other for history versions. The organization for current versions follows an efficient storage organization of a conventional nontemporal data base. However, for maintaining the history versions of each item in the data base, we use an extended version of a Fibonacci heap, referred to as a history version heap. The novelty of our approach resides in its ability to insert a new version for an item into the data base in O (1) amortized time and retrieve the oldest version of an item in O (1) amortized time. These bounds are irrespective of the number of existing versions for that item. In addition, we can access or delete any version of a given item in logarithmic amortized time. Because our approach treats the current store and history store differently, it uses different access methods for each store possible.\",\n \"Title: On optimizing compatible security policies in wireless networks\\nYear: 2006\\n\\nAbstract: This paper deals with finding the maximum number of security policies without conflicts. By doing so we can remove security loophole that causes security violation. We present the problem of maximum compatible security policy and its relationship to the problem of maximum acyclic subgraph, which is proved to be NP-hard. Then we present a polynomial-time approximation algorithm and show that our result has approximation ratio 1 + 1/k for any integer k with complexity O(Nk+1).\",\n \"Title: Lossy Communicating Finite State Machines\\nYear: 2004\\n\\nAbstract: network of communicating finite state machines (CFSM) consists of a set of finite state machines that communicate asynchronously with each other over (potentially) unbounded FIFO channels by sending and receiving typed messages. As a concurrency model, CFSMs has been widely used to specify and validate communications protocols. In this paper we propose to extend the classical CFSM model by introducing a new type of actions --- the deletion action. The resulted model is called lossy communicating finite state machines (LCFSMs). The LCFSM model remedies two weaknesses in classical CFSM model. We show that the LCFSM model allows specification and verification of unreliable communication channels with no need of extra CFSMs. The LCFSM model enables more succinct specification and verification of communication protocols that use unreliable communication channels. LCFSM paradigm can also be used to concisely model communication errors such as dropping datagrams in UDP due to lack of local buffers.\",\n \"Title: A modular methodology to verify communication protocols\\nYear: 1997\\n\\nAbstract: State explosion has been a major problem for verifying communication protocols and distributed algorithms. In this paper we analyze the sources that cause the state explosion problem and propose a modular approach to verifying communication protocols based on networks of communicating finite state machines (CFSMs). Our proposed method is innovative and its time and space complexity is independent of the number of processes in a system. The new methodology can significantly reduce the time and space needed to verify a number of interesting logical properties, as evidenced by our implementations.\",\n \"Title: Automatic detection of errors in distributed systems\\nYear: 1995\\n\\nAbstract: Debugging in a distributed environment is very complex when compared to debugging in a uniprocessor or sequential environment. The order of events in a distributed environment is not deterministic, and this order of events may some times produce some unexpected errors. These errors which depend on the timing of events are typical of distributed systems. In this paper we proposed an approach based on the timing graphs concept to debug these timing errors. Here we give some conditions which should be satisfied by a timing graph, if the execution of that instance of the program, from which the graph is constructed, doesn’t have any errors. The graphs are constructed using the information gathered at the run time using tracing mechanism. This approach uses topological sorting of directed acyclic graphs in analyzing the timing graphs. In this paper, we have developed the theory behind this approach and presented an algorithm to automate the procedure. Since the manual approach to this problem is cumbersome and error prone, this automatic error detection procedure simplifies the detection of the cause of the error for some standard error patterns.\",\n \"Title: Achieving Flow Level Constant Performance Guarantees for CICQ Switches without Speedup\\nYear: 2010\\n\\nAbstract: Performance guarantees provided by switches can be at different granularity: port level and flow level. As a trade-off, it is usually more expensive to provide performance guarantees at finer granularity. Existing solutions for switches to provide flow level performance guarantees require either expensive hardware support or centralized scheduling algorithms with multiple iterations. In this paper, we present the Flow-level Fair Scheduling (FFS) algorithm to provide flow level performance guarantees for Combined-Input- Crosspoint-Queued (CICQ) switches, which are special crossbar switches with a small exclusive buffer at each crosspoint of the crossbar. FFS uses hierarchical and multidimensional fair queueing to emulate the ideal Generalized Processing Sharing (GPS) model. The main features of FFS include: constant performance guarantees, bounded crosspoint buffer sizes, no speedup requirement, and distributed operation. We theoretically analyze the performance of FFS, and conduct simulations to verify the analytical results.\",\n \"Title: Belief based data cleaning for wireless sensor networks\\nYear: 2012\\n\\nAbstract: Wireless sensor network (WSN) data is often subjected to corruption and losses due to wireless medium of communication and presence of hardware inaccuracies in the nodes. For a WSN application to deduce an appropriate result it is necessary that the data received is clean, accurate, and lossless. WSN data cleaning systems exploit contextual associations existing in the received data to suppress data inconsistencies and anomalies. In this work we attempt to clean the data gathered from WSN by capturing the influence of changing dynamics of the environment on the contextual associations existing in the sensor nodes. Specifically, our work validates the extent of similarities among the sensed observations from contextually (spatio-temporally) associated nodes and considers the time of arrival of data at the sink to educate the cleaning process about the WSN's behavior. We term the data cleaning technique proposed in this work as time of arrival for data cleaning (TOAD). TOAD establishes belief on spatially related nodes to identify potential nodes that can contribute to data cleaning. By using information theory concepts and experiments on data sets from a real-time scenario we demonstrate and establish that validation of contextual associations among the sensor nodes significantly contributes to data cleaning. Copyright © 2010 John Wiley & Sons, Ltd.\",\n \"Title: On Quality Of Service Routing in Ad-Hoc Networks\\nYear: 2003\\n\\nAbstract: Ad-hoc networks can be formally defined as acollection of wireless mobile hosts dynamically forminga temporary network without the aid of any existingestablished infrastructure or centralized admission[1].The main focus of the paper is the extension to the QoSrouting procedure, which can inform the source qualityof service available to any destination in the wirelessnetwork. The Ad-Hoc On Demand Distance VectorRouting Protocol (AODV) is taken into considerationand an extension to the protocol has been suggested tosupport Quality of Service.\",\n \"Title: Efficient solutions to multicast routing in communication networks\\nYear: 1996\\n\\nAbstract: An important problemin both wireless and wired communication networks is to be able to efficiently multicast information to a group of network sites. Multicasting reduces the transmission overhead of both wireless and wired networks and the time it takes for all the nodes in the subset to receive the information. Since transmission bandwidth is a scarce commodity especially in wireless networks, efficient and near minimum-cost multicast algorithms are particularly useful in the wireless context. In this paper, we discuss methods of establishing efficient and near minimum-cost multicast routing in communication networks. In particular, we discuss an efficient implementation of a widely used multicast routing method which can construct a multicast tree with a cost no greater than twice the cost of an optimal tree. We also present two efficient multicast tree constructions for a general version of the multicast routing problem in which a network consists of different classes of nodes, where each class can have one or more nodes of the same characteristic which is different fromthe characteristics of nodes fromother classes. Because of their efficient running times, these multicast routing methods are particularly useful in the mobile communication environments where topology changes will imply recomputation of the multicast trees. Furthermore, the proposed efficient and near minimum-cost multicast routing methods are particularly suited to the wireless communication environments, where transmission bandwidth is more scarce than wired communication environments.\",\n \"Title: A future location-aware replacement policy for the cache management at the mobile terminal\\nYear: 2009\\n\\nAbstract: While the traditional data shipping systems use physical information to organize data, a newer data caching technique maintains both associated answers (data items) of previous queries and their meaning (purpose). This form of information description is called semantic description, and it makes it possible to reason about and derive knowledge from the given description. In a distributed heterogeneous environment, such as the mobile environment, the semantic data caching paradigm is an important technique for improving the performance of wireless data dissemination systems. Data caching performance depends heavily on the replacement policy being used for the cache management. However, future location uncertainty, limited client resources and frequent client disconnections make cache management a challenge. This paper proposes a future location-aware cache replacement policy to manage a semantic cache. The proposed replacement policy uses the validity of the data fetched from the server and the neighboring locations to decide which of the cache entries is less likely to be needed in the future, and therefore a good victim for eviction when cache space is needed. The replacement policy's preference for cached items to be evicted is modeled as a general function that declines with distance between the mobile user's current location and the candidate for replacement cached item's bound location. For better efficiency, the overall replacement granularity is dynamically achieved along three levels: ring, cell and data item. Simulation study of the proposed approach shows that it outperforms both the least recently used (LRU) and furthest away replacement (FAR) schemes, where only temporal locality is considered. Moreover, the proposed scheme is easier to implement than other research and development proposals. Copyright © 2008 John Wiley & Sons, Ltd.\",\n \"Title: A proactive secure routing algorithm defense against node compromise in sensor networks\\nYear: 2008\\n\\nAbstract: Providing a secure routing algorithm that defend against node compromise is a challenging task in sensor networks. In this paper, we propose a proactive secure routing algorithm (PSR) to conquer the undetected compromised nodes-the compromised nodes that the system has not detected them yet. Compared with other secure routing algorithms or ideas, routing paths in PSR not only bypass the detected compromised nodes but also bypass the nodes with larger probabilities of being compromised. To estimate the probability of node compromise, we introduce a node compromise distribution model. Simulations show that PSR is effective to prevent routing path from passing compromised nodes whether detected or not.\",\n \"Title: A parallel algorithm for the Steiner tree problem\\nYear: 1993\\n\\nAbstract: The Steiner problem in graphs is to find the minimum cost tree which spans at least a given subset of V, where V is the set of vertices in the graph. This problem has a wide variety of practical applications, including wire routing in physical VLSI design. Since the problem is NP-complete, much work has been devoted to developing approximate solutions such as the one proposed by V.J. Rayward-Smith (1988). In this paper, we identify the Rayward-Smith's algorithm as being appropriate for parallelization, and describe a parallel implementation of that algorithm. We also show that linear speedup is achievable on the PRAM model with the number of processors p⩽|V|\",\n \"Title: Performance Analysis Of Dsr Using Cached Route Replies For Multihop Wireless Networks\\nYear: 2005\\n\\nAbstract: Effective routing in multihop wireless networks is an interesting problem to solve because of the nature of multihop wireless networks. We use the DSR as an example of on demand routing protocol for multihop wireless networks to show the effectiveness of cache-enabled scheme. We present the performance evaluation of the enhanced routing scheme of using cached route replies for the DSR. Through simulation analysis, we demonstrate the effectiveness of this scheme in an on-demand (reactive) routing protocol. We collect the different performance statistics and show through simulation results that the performance is improved in terms of total traffic, routing traffic (overhead), and route discovery time and download response time. We have used OPNET modeler for simulating our scheme for multihop wireless network.\",\n \"Title: Video Content Representation Based on Texture and Lighting\\nYear: 2000\\n\\nAbstract: When dealing with yet unprocessed video, structuring and extracting features according to models that reflect the idiosyncrasies of a video data category (film, news, etc.) are essential for guaranteeing the content annotation, and thus the use of video. In this paper, we present methods for automatic extraction of texture and lighting features of representative frames of video data shots. These features are the most important elements which characterize the development of plastic (physical) space in the film video. They are also important in other video categories. Texture and lighting are two basic properties, or features, of video frames represented in the general film model presented in [12]. This model is informed by the internal components and interrelationships known and used in the film application domain. The method for extraction of texture granularity is based on the approach for measuring the granularity as the spatial rate of change of the image intensity [3], where we extend it to color textures. The method for extraction of lighting feature is based on the approach of closed solution schemes [4], which we improve by making it more general and more effective.\",\n \"Title: Mobile users in heterogeneous environments with middleware platform\\nYear: 2003\\n\\nAbstract: Mobile computing is becoming more and more pervasive, liberating users from the confines of wired networks. At the same time, transparent access to heterogeneous, distributed information sources has become a reality in wired computing. Obviously, this kind of access is highly desirable for mobile users, too. However, current architectures for transparent information access do not take the specific needs of mobile users into account, while existing architectures for mobile computing do not support transparent access well. For the future growth of the usage of mobile computing it is of utmost importance that instead of individually developed, isolated extensions to the existing architectures, the research community agrees on a strong, standardized middleware platform extending both existing mobile architectures and existing information access architectures to ensure mobile access in heterogeneous environments. In this paper we propose such a platform.\",\n \"Title: Thermal aware clock synthesis considering stochastic variation and correlations\\nYear: 2008\\n\\nAbstract: In this paper, we have proposed a thermal aware routing based parameterization to generate a clock model that takes the stochastic temperature variation into consideration. The worst-case skew is calculated by using the transient analysis. The proposed Thermal Aware Routing based Clock Tree Optimization (TARCO) is performed level by level via the use of sensitivities from the proposed macromodel. The experimental results show that our algorithm reduces up to 5X worst-case skew in comparison to the existing bonded-skew based Deferred Merge Embedding (DME) approach, and 1.7X worst-case skew compared to Perturbation based Clock Optimization (PECO) and 2.1X compared to Temperature Aware Clocktree Optimization (TACO).\",\n \"Title: On Peer-To-Peer Location Management In Vehicular Ad Hoc Networks\\nYear: 2009\\n\\nAbstract: Vehicular ad-hoc networks (VANETs) have been gained importance for the inter-vehicle communication that supports local communication between vehicles without any expensive infrastructure and considerable configuration efforts. How to provide light-weight and scalable location management service which facilitates geographic routing in VANETs remains a fundamental issue. In this paper we will present a novel peer-to-peer location management protocol, called PLM, to provide location management service in VANETs. PLM makes use of high mobility in VANETs to disseminate vehicles' historical location information over the network. A vehicle is able to predict current location of other vehicles with Kalman filtering technique. Our theoretical analysis shows that PLM is able to achieve high location information availability with a low protocol overhead and latency. The simulation results indicate that PLM can provide fairly accurate location information with quite low communication overhead in VANETs.. [Article copies are available for purchase from InfoSci-on-Demand.com]\",\n \"Title: Self-organized forensic support in MANETs\\nYear: 2008\\n\\nAbstract: A distributed hash table (DHT) based approach for supporting forensic capability in mobile ad hoc networks (MANETs) is presented. The DHT-based approach has been modified to inhibit recursive increase in bandwidth consumption due to forensic activity - the process of logging is associated with that of packet delivery via customizable decreasing functions. Simulation has revealed that this approach limits the bandwidth requirement for forensic activities, although it requires a trade-off between bandwidth consumption and effective logging. The focus is to design a self-organized logging system over networks with dynamic topology.\",\n \"Title: A Real-Time Wireless Route Guidance System for Urban Traffic Management and Its Performance Evaluation\\nYear: 2009\\n\\nAbstract: Selecting optimal routes to reduce travel time has been an important research area for urban traffic network managements. Various parameters such as route length, average speed and event situations need to be considered in the design of a route guidance system. In this paper, we develop a new navigation system based on the combination of fastest path search algorithm and travel time prediction method for urban traffic areas. Compared with previous route guidance systems, the results reveal that our system, applying the prediction based realtime fastest path (PRFP) algorithm, can significantly reduce the travel time especially when customers travel in a complex route environment and face frequent congestion. We also demonstrate the advantages of this system and verify the results using simulation.\",\n \"Title: Dynamic key management for secure routing in MANET\\nYear: 2007\\n\\nAbstract: A secure key management scheme for the locality caching multi-root multi-generation (LCMRMG) MANET routing algorithm is proposed. The scheme takes advantage of the multi-root nature of LCMRMG and successfully integrates public key, certification and threshold technologies. The scheme is hierarchical and fully distributed. The key management operations are flexible in secure share distribution and scalable well to large MANET. Extensive simulations have shown that the scheme is secure, robust, efficient, and scalable. Copyright (C) 2007 John Wiley & Sons, Ltd.\",\n \"Title: A New Network Topology Evolution Generator Based on Traffic Increase and Distribution Model\\nYear: 2007\\n\\nAbstract: Following traffic increase near to network backbone capacity in a domain network, the evolution of backbone topology takes place. In this paper, three main types of evolution methods: link upgrading only method (upgrade link capacity only), node upgrading method (add nodes and links with the same link capacity), and the combinations of previous two are explored. To shunt the saturated traffic efficiently, we propose several node upgrading generators - Adapting Traffic Evolution Topology gEnerators (ATETEs). ATETEs consider traffic distribution and node burden conditions and select the congested link as the main shunting object. The difference among ATETEs lies that they have diverse strategies to choose a node in the congested link as the second shunting aim. Simulation shows that: the type of ATETEs which picks the burdened node in the saturated link as another shunting object has the most effective shunting result. Compare with most of current topology generators such as [BRITE] in [1] which consider little about traffic increase distribution, ATETEs are more efficient to satisfy traffic increase.\",\n \"Title: Spatio-Temporal Modeling in Video and Multimedia Geographic Information Systems\\nYear: 2001\\n\\nAbstract: The geographic application domain includes important information such as design plans, record drawings, photographs, and video data records. The corresponding geographic information systems (GISs) should maintain a specific model for each geographic data modality such as geographic video model for video records. Real-time 3-D geographic information systems provide comprehensive interface to complex and dynamic databases and truly immersive capability for visualizing geographic data. In cases, where information about location of geographic objects is needed at different moments of time, a GIS should process video data that is directly manipulated and retrieved through representation of its spatio-temporal characteristics. In this context, the most advanced multimedia form—digital video, finds an efficient application in GIS for versatile specification of geographic data. In this paper, a model for spatial data evolving with time is introduced in the context of video data manipulation. We designed a model that represents the spatio-temporal continuum among geographic objects in geographic video sequences, or digital video. The model developed here was motivated by the requirements for manipulating, managing, and analyzing geographic data for the necessities of infrastructure management, urban and regional planning, hazard prevention and management, transportation networks, vehicles routing, etc. This model allows the important issues for GIS such as conditions of adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close one geographic object is to another) to be determined. Our model describes the spatial relationships among objects for each key frame in a given video scene, and the temporal relationships of the temporal intervals measuring the validity duration of the spatial relationships spanning over the given key frame. One of the main GIS issues—distance estimation, is solved as quantitative metrics of geographic objects in digital video are easily and precisely specified. This model is a basis for annotation of raw video for subsequent use in geographic video databases and digital libraries that provide access to and efficient storage of large volume of geographic data.\",\n \"Title: The Steiner tree problem with minimum number of vertices in graphs\\nYear: 1992\\n\\nAbstract: The Steiner tree problem is to find a tree in a connected undirected distance graph G=(V, E, d) which spans a given set S⊆V. The minimum Steiner tree for G and S is a tree which spans S with a minimum total distance on its edges. The authors consider a special case of the Steiner tree problem in graphs. For this problem they assume that the underlying graph G does not have any direct edge between the vertices in S⊆V. The problem is to find a tree in G which spans the vertices in S and uses minimum number of vertices in V-S\",\n \"Title: Locality caching multiroot multigeneration routing algorithm in mobile ad hoc networks\\nYear: 2003\\n\\nAbstract: A locality caching multiroot multigeneration (LCMRMG) routing algorithm for mobile ad hoc networks (MANET). The LCMRMG algorithm extends and significantly enhances a previously proposed single-root MANET routing algorithm. Hosts in a LCMRMG MANET cache the locality of network traffic routing through them. Based on the cached locality statistics, a host can calculate the estimated reduction of network traffic if it becomes a new root router and can elect to do so if the reduction exceeds a predefined threshold value.\",\n \"Title: Spatio-temporal composition of video objects: representation and querying in video database systems\\nYear: 2001\\n\\nAbstract: A key characteristic of video data is the associated spatial and temporal semantics. It is important that a video model models the characteristics of objects and their relationships in time and space. J.F. Allen's (1983) 13 temporal relationships are often used in formulating queries that contain the temporal relationships among video frames. For the spatial relationships, most of the approaches are based on projecting objects on a two or three-dimensional coordinate system. However, very few attempts have been made formally to represent the spatio-temporal relationships of objects contained in the video data and to formulate queries with spatio-temporal constraints. The purpose of the work is to design a model representation for the specification of the spatio-temporal relationships among objects in video sequences. The model describes the spatial relationships among objects for each frame in a given video scene and the temporal relationships (for this frame) of the temporal intervals measuring the duration of these spatial relationships. It also models the temporal composition of an object, which reflects the evolution of object's spatial relationships over the subsequent frames in the video scene and in the entire video sequence. Our model representation also provides an effective and expressive way for the complete and precise specification of distances among objects in digital video. This model is a basis for the annotation of raw video\",\n \"Title: Belief-free equilibrium of packet forwarding game in ad hoc networks under imperfect monitoring\\nYear: 2010\\n\\nAbstract: Future applications will require autonomous devices to be interconnected and form ad hoc networks. In such networks, cooperation will be the first problem to solve at all layers of the protocol stack. This paper deals with one of the basic functions of a network, namely packet forwarding. We model packet forwarding as a stochastic game in which each node monitors the behavior of its neighbors. We consider the realistic scenario when the monitoring technology used by the nodes is imperfect. In reality, there can be inconsistencies between the true action of a node and the observations of its neighbors. Therefore, in an ad hoc network, each node receives only noisy private information about the past play of its neighbors. We develop a simple one period memory strategy that constrains self-interested nodes to cooperate under noise. We use a belief-free approach. A belief-free approach delivers a tremendous computational advantage because nodes' belief about the neighbors' private history does not need to be computed. We support our results by mathematical proofs and simulations.\",\n \"Title: Game Theoretic Modeling and Evolution of Trust in Autonomous Multi-Hop Networks: Application to Network Security and Privacy\\nYear: 2011\\n\\nAbstract: Future applications will require autonomous devices to be interconnected to form a network. Such networks will not have a central manager; each node will manage itself and will be free to decide participation in any network function. As with traditional networks, these networks need to be secured to authenticate the nodes, prevent misuse, detect anomalies and protect user privacy. Network security and privacy protection without a central manager will be challenging. Several security mechanisms and privacy protections will require the cooperation of several nodes to defend the network from malicious attacks. We particularly investigate when for each node it is cost-effective to freely participate in the security mechanism or protect its privacy depending if that node believes or trusts that all other nodes or at least a minimum number of other nodes will do the same. In this case, each node will be involved in a trust dilemma that we will model using the mathematical framework of game theory and evolutionary game theory. The well known stag hunt game will be our basic game model. This paper will clearly present the interconnection between cooperation, trust, privacy and security in a network.\",\n \"Title: Mobile learning object authoring tool and management system for mobile ad hoc wireless networks\\nYear: 2015\\n\\nAbstract: Mobile learning can augment formal education and bridge the gap between formal and informal education by creating extended learning communities using any digital technology in connected or infrastructure-less environments. With the use of ad hoc networks and mobile authoring tools, we can now create an 'on-the-fly' learning scenario, where learners can create, share, and view content from their mobile devices without the need for server-client or infrastructure-based liaisons. Mobile learning, however, is not just about sharing content or learning using mobile, wireless, and portable devices. Rather, it is learning across spatiotemporal contexts that enables learners to form knowledge and understanding in different scenarios. When facing limited resources stemming from the characteristics of mobility and wireless technologies, determining the best practices for content creation and delivery becomes a challenge. This paper describes the architecture of a mobile-focused learning network designed so that learning tools, activities, contexts, and interactions are created as necessary over time and space while adhering to traditional learning object standards. Copyright © 2015John Wiley & Sons, Ltd.\",\n \"Title: Game theoretic modeling of security and trust relationship in cyberspace\\nYear: 2016\\n\\nAbstract: AbstractToday, online network services have evolved as the highest-emergent medium, enabling various online activities to be lucrative. However, these lucrative activities also bring new forms of privacy threats to the community. In a reliable e-business service, users should be able to trust the providers of the service to protect their customers' privacy. The service providers should not risk the personal and private information about their customers in cyberspace. There is an economic gain for a business provider when users trust the service provider. Despite those benefits, cyber security concern is the main reason some large organization may go bankrupted. Unfortunately, attackers may attempt to breach a provider's database and expose customers' private information. Therefore, in this paper, we propose a game theoretic framework for security and trust relationship in cyberspace for users, service providers, and attackers. Mathematical proofs and evaluations support our model. Service providers may use the model to see how important and dissuasive against attackers is when investing in cybersecurity. Copyright © 2016 John Wiley & Sons, Ltd.\",\n \"Title: A Game-Theoretic Approach On Resource Allocation With Colluding Nodes In Manets\\nYear: 2016\\n\\nAbstract: Prevalent concerns with dynamic networks typically involve security. Especially with resource constraints in dynamic networks such as mobile ad-hoc networks (MANETs), security needs to be of particular consideration. In this paper, we first analyze the solution concept involved in optimizing resource allocation and data packet forwarding. In a MANET, the availability of having data packets forwarded may be insubstantial due to the presence of selfish nodes. Nodes may not want to participate in the network to preserve their own resources. We propose a packet-forwarding problem model with a negotiation game, where an arbitrator acts as a cluster head and initiates a bargaining game. Thereafter, we consider the possibility of having some group of nodes exhibit malicious behavior and collude to subvert the MANET. We investigate the problem by finding the optimal Nash Equilibrium (NE) strategies of the negotiation game. Then, we simulate the effect of the coalition of malicious nodes in a mobile environment. Simulation results support our model.\",\n \"Title: Game theoretic analysis for resource allocation in dynamic multi-hop networks with arbitration\\nYear: 2017\\n\\nAbstract: A connection through a mobile node may not be available because of the greediness of selfish nodes. In this paper, we address the issue of dynamic packet forwarding by a set of wireless autonomous ad hoc nodes. Wireless nodes acting in a selfish manner try to use the resources of other nodes without their own participation. We model the dynamic packet forwarding problem as a negotiation game with an arbitrator. In our model, a group of mobile nodes requesting to forward packets negotiates with a mobile arbitrator until an agreement at least by simple majority is reached on a resource allocation. The mobile arbitrator submits offers to each mobile device in the group, and the mobile nodes decide to agree or disagree on the offer. The ultimate decision is made by simple majority. We investigate and solve the negotiation by finding the optimal Nash Equilibrium strategies of the game. We consider offers generated from Dirichlet's distribution for an ensemble of mobile devices over a finite and sporadic time limitation. The solution obtained from negotiation ensures that a mobile device always finds a peer or arbitrator to help forward packets and keep the network flowing. Mathematical proofs and MATLAB simulations support our model.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":63,"string":"63"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":65,"string":"65"}}},{"rowIdx":66,"cells":{"question_id":{"kind":"string","value":"Teruko Mitamura"},"question":{"kind":"string","value":"Generate an abstract for the title \"Evaluation metrics for knowledge-based machine translation\" using the following items: 1. Methodology\n2. Machine Translation Evaluation\n3. Causal Error Analysis\n4. Knowledge-Based Machine Translation\n5. KANT Machine Translation System"},"answer":{"kind":"string","value":"A methodology is presented for component-based machine translation (MT) evaluation through causal error analysis to complement existing global evaluation methods. This methodology is particularly appropriate for knowledge-based machine translation (KBMT) systems. After a discussion of MT evaluation criteria and the particular evaluation metrics proposed for KBMT, we apply this methodology to a large-scale application of the KANT machine translation system, and present some sample results."},"correct_answer":{"kind":"string","value":"A methodology is presented for component-based machine translation (MT) evaluation through causal error analysis to complement existing global evaluation methods. This methodology is particularly appropriate for knowledge-based machine translation (KBMT) systems. After a discussion of MT evaluation criteria and the particular evaluation metrics proposed for KBMT, we apply this methodology to a large-scale application of the KANT machine translation system, and present some sample results."},"documents":{"kind":"list like","value":["Title: Source language diagnostics for MT.\nYear: 2003\n\nAbstract: This paper presents a source language diagnostic system for controlled translation. Diagnostics were designed and implemented to address the most difficult rewrites for authors, based on an empirical analysis of log files containing over 180,000 sentences. The design and implementa- tion of the diagnostic system are presented, along with experimental results from an empirical evaluation of the completed system. We found that the diagnostic system can correctly identify the problem in 90.2% of the cases. In addition, depending on the type of grammar problem, the diagnostic system may offer a rewritten sentence. We found that 89.4% of the rewritten sentences were correctly rewritten. The results suggest that these methods could be used as the basis for an automatic rewriting system in the future.","Title: Lexicons\nYear: 1989\n\nAbstract: The three lexicons used by KBMT-89 are described: A concept lexicon constitutes the sublanguage domain model for specifying semantic information; it is maintained by Ontos, a knowledge-acquisition and maintenance system. An analysis lexicon is a dictionary containing syntactic information and mapping rules required for semantic parsing. And a generation lexicon, similar to the analysis lexicon, is employed in the generation phase.","Title: Analysis and generation grammars\nYear: 1989\n\nAbstract: This paper describes the analysis and generation grammars for English and Japanese as they were employed in the KBMT-89 program. We discuss word order, coordination, subcategorization, morphological rules, rule ordering and bi-directional grammars.","Title: A fast, accurate deterministic parser for Chinese\nYear: 2006\n\nAbstract: We present a novel classifier-based deterministic parser for Chinese constituency parsing. Our parser computes parse trees from bottom up in one pass, and uses classifiers to make shift-reduce decisions. Trained and evaluated on the standard training and test sets, our best model (using stacked classifiers) runs in linear time and has labeled precision and recall above 88% using gold-standard part-of-speech tags, surpassing the best published results. Our SVM parser is 2-13 times faster than state-of-the-art parsers, while producing more accurate results. Our Maxent and DTree parsers run at speeds 40-270 times faster than state-of-the-art parsers, but with 5-6% losses in accuracy.","Title: Robust Speech Dialog Interface For Car Telematics Service\nYear: 2004\n\nAbstract: In this paper, we describe new consumer services based on speech processing technologies to support a new digital/mobile era of ubiquitous communication. First, we propose a compact and noise robust embedded speech recognition middleware implemented on microprocessors focused on sophisticated HMIs (Human Machine Interfaces) for car information systems (i.e. Car Telematics). Second, we report on a novel and sophisticated Dialog Management/Manager (DM) system based on VoiceXML (Voice eXtensible Markup Language), called CAMMIA (Conversational Agent for Multimedia Mobile Information Access). The proposed DM will handle two important issues: an automatic generation scheme for lexicons and grammars, and an effective combination/merger between Automatic Speech Recognition (ASR) and Natural Language Processing (NLP). The new DM scheme has been evaluated for an application of the Car Telematics service task after integration with ASR and a VoiceXML interpreter (VXI).","Title: Parallel Syntactic Annotation of Multiple Languages\nYear: 2006\n\nAbstract: This paper describes an effort to investigate the incrementally deepening development of an interlingua notation, validated by human annotation of texts in English plus six languages. We begin with deep syntactic annotation, and in this paper present a series of annotation manuals for six different languages at the deep-syntactic level of representation. Many syntactic differences between languages are removed in the proposed syntactic annotation, making them useful resources for multilingual NLP projects with semantic components.","Title: Deriving Semantic Knowledge from Descriptive Texts Using an MT System\nYear: 2002\n\nAbstract: This paper describes the results of a feasibility study which focused on deriving semantic networks from descriptive texts using controlled language. The KANT system [3,6] was used to analyze input paragraphs, producing sentence-level interlingua representations. The interlinguas were merged to construct a paragraph-level representation, which was used to create a semantic network in Conceptual Graph (CG) [1] format. The interlinguas are also translated (using the KANTOO generator) into OWL statements for entry into the Ontology Works electrical power factbase [9]. The system was extended to allow simple querying in natural language.","Title: The JAVELIN Question-Answering System at TREC 2003: A Multi-Strategh Approach with Dynamic Planning\nYear: 2003\n\nAbstract: The JAVELIN system evaluated at TREC 2003 is an integrated architecture for open-domain question answering. JAVELIN employs a mod- ular approach that addresses individual aspects of the QA task in an abstract manner. The Sys- tem implements a planner that controls the ex- ecution and information flow, as well as a mul- tiple answer seeking strategies used differently depending on the type of question.","Title: Controlled language for multilingual machine translation.\nYear: 1999\n\nAbstract: In this paper, we present an overview of the issues in designing a controlled language, the implementation of a controlled language checker, and the deployment of KANT Con- trolled English for multilingual machine translation. We also discuss some success criteria for introducing controlled language. Finally, future vision of KANT controlled language development is discussed.","Title: An English-to-Turkish Interlingual MT System\nYear: 1998\n\nAbstract: This paper describes the integration of a Turkish generation system with the KANT knowledge-based machine translation system to produce a prototype English-Turkish interlingua-based machine translation system. These two independently constructed systems were successfully integrated within a period of two months, through development of a module which maps KANT interlingua expressions to Turkish syntactic structures. The combined system is able to translate completely and correctly 44 of 52 benchmark sentences in the domain of broadcast news captions. This study is the first known application of knowledge-based machine translation from English to Turkish, and our initial results show promise for future development.","Title: Probabilistic models for answer-ranking in multilingual question-answering\nYear: 2010\n\nAbstract: This article presents two probabilistic models for answering ranking in the multilingual question-answering (QA) task, which finds exact answers to a natural language question written in different languages. Although some probabilistic methods have been utilized in traditional monolingual answer-ranking, limited prior research has been conducted for answer-ranking in multilingual question-answering with formal methods. This article first describes a probabilistic model that predicts the probabilities of correctness for individual answers in an independent way. It then proposes a novel probabilistic method to jointly predict the correctness of answers by considering both the correctness of individual answers as well as their correlations. As far as we know, this is the first probabilistic framework that proposes to model the correctness and correlation of answer candidates in multilingual question-answering and provide a novel approach to design a flexible and extensible system architecture for answer selection in multilingual QA. An extensive set of experiments were conducted to show the effectiveness of the proposed probabilistic methods in English-to-Chinese and English-to-Japanese cross-lingual QA, as well as English, Chinese, and Japanese monolingual QA using TREC and NTCIR questions.","Title: Automatic collocation suggestion in academic writing\nYear: 2010\n\nAbstract: In recent years, collocation has been widely acknowledged as an essential characteristic to distinguish native speakers from non-native speakers. Research on academic writing has also shown that collocations are not only common but serve a particularly important discourse function within the academic community. In our study, we propose a machine learning approach to implementing an online collocation writing assistant. We use a data-driven classifier to provide collocation suggestions to improve word choices, based on the result of classification. The system generates and ranks suggestions to assist learners' collocation usages in their academic writing with satisfactory results.","Title: Interlingual annotation of parallel text corpora: A new framework for annotation and evaluation\nYear: 2010\n\nAbstract: This paper focuses on an important step in the creation of a system of meaning representation and the development of semantically annotated parallel corpora, for use in applications such as machine translation, question answering, text summarization, and information retrieval. The work described below constitutes the first effort of any kind to annotate multiple translations of foreign-language texts with interlingual content. Three levels of representation are introduced: deep syntactic dependencies (IL0), intermediate semantic representations (IL1), and a normalized representation that unifies conversives, nonliteral language, and paraphrase (IL2). The resulting annotated, multilingually induced, parallel corpora will be useful as an empirical basis for a wide range of research, including the development and evaluation of interlingual NLP systems and paraphrase-extraction systems as well as a host of other research and development efforts in theoretical and applied linguistics, foreign language pedagogy, translation studies, and other related disciplines.","Title: Effects of adaptive prompted self-explanation on robust learning of second language grammar\nYear: 2011\n\nAbstract: Prompted self-explanation is a successful intervention for many domains. However, in our previous work within the domain of second language grammar learning, we found no advantage for self-explanation over practice alone. Here, we continue testing the generality of self-explanation through the development of an adaptive self-explanation tutor and report on results of a classroom evaluation (N=92) in which we compare the adaptive tutor to a practice-only tutor. We investigate both procedural and declarative knowledge acquisition as well as long-term retention. Results show that while self-explanation takes more time than practice alone, it leads to greater learning of declarative knowledge. However, there are no differences between conditions on immediate or long-term retention measures of procedural knowledge.","Title: The JAVELIN Question-Answering System at TREC 2002\nYear: 2002\n\nAbstract: This paper describes the JAVELIN approach for open-domain question answering (Justification-based AnswerValuation through Language Interpretation), and our participation in the TREC 2002 question-answeringtrack. The main scientific tenets underlying JAVELIN are:QA as Planning. Question Answering is a complex multi-faceted task, where question type, informationavailability, user needs, and NLP sophistication of QA modules all combine dynamically to determine the optimal QA strategy....","Title: GE-CMU: description of the SHOGUN system used for MUC-5\nYear: 1993\n\nAbstract: This paper describes the GE-CMU TIPSTER/SHOGUN system as configured for the TIP-STER 24-month (MUC-5) benchmark, and gives details of the system's performance on the selected Japanese and English texts. The SHOGUN system is a distillation of some of the key ideas that emerged from previous benchmarks and experiments, emphasizing a simple architecture in which the focus is on detailed corpus-based knowledge. This design allowed the project to meet its goal of achieving advances in coverage and accuracy while showing consistently good performance across languages and domains.","Title: Interlingual Annotation for MT Development\nYear: 2004\n\nAbstract: MT systems that use only superficial representations, including the current generation of statistical MT systems, have been successful and useful. However, they will experience a plateau in quality, much like other \"silver bullet\" approaches to MT. We pursue work on the development of interlingual representations for use in symbolic or hybrid MT systems. In this paper, we describe the creation of an interlingua and the development of a corpus of semantically annotated text, to be validated in six languages and evaluated in several ways. We have established a distributed, well-functioning research methodology, designed a preliminary interlingua notation, created annotation manuals and tools, developed a test collection in six languages with associated English translations, annotated some 150 translations, and designed and applied various annotation metrics. We describe the data sets being annotated and the interlingual (IL) representation language which uses two ontologies and a systematic theta-role list. We present the annotation tools built and outline the annotation process. Following this, we describe our evaluation methodology and conclude with a summary of issues that have arisen.","Title: Evaluating Textual Entailment Recognition for University Entrance Examinations\nYear: 2012\n\nAbstract: The present article addresses an attempt to apply questions in university entrance examinations to the evaluation of textual entailment recognition. Questions in several fields, such as history and politics, primarily test the examinee’s knowledge in the form of choosing true statements from multiple choices. Answering such questions can be regarded as equivalent to finding evidential texts from a textbase such as textbooks and Wikipedia. Therefore, this task can be recast as recognizing textual entailment between a description in a textbase and a statement given in a question. We focused on the National Center Test for University Admission in Japan and converted questions into the evaluation data for textual entailment recognition by using Wikipedia as a textbase. Consequently, it is revealed that nearly half of the questions can be mapped into textual entailment recognition; 941 text pairs were created from 404 questions from six subjects. This data set is provided for a subtask of NTCIR RITE (Recognizing Inference in Text), and 16 systems from six teams used the data set for evaluation. The evaluation results revealed that the best system achieved a correct answer ratio of 56%, which is significantly better than a random choice baseline.","Title: Keyword Translation from English to Chinese for Multilingual QA\nYear: 2004\n\nAbstract: The Keyword Translator is a part of the Question Analyzer module in the JAVELIN Question-Answering system; it translates the keywords, which are used to query documents and extract answers, from one language to another. Much work has been in the area of query translation for CLIR or MLIR, however, many have focused on methods using hard-to-obtain and domain-specific resources, and evaluation is often based on retrieval performance rather than translation correctness. In this paper we will describe methods combining easily accessible, general-purpose MT systems to improve keyword translation correctness. We also describe methods that utilize the question sentence available to a question-answering system to improve translation correctness. We will show that using multiple MT systems and the question sentence to translate keywords from English to Mandarin Chinese can significantly improve keyword translation correctness.","Title: Resources for the Detection of Conventionalized Metaphors in Four Languages.\nYear: 2014\n\nAbstract: This paper describes a suite of tools for extracting conventionalized metaphors in English, Spanish, Farsi, and Russian. The method depends on three significant resources for each language: a corpus of conventionalized metaphors, a table of conventionalized conceptual metaphors (CCM table), and a set of extraction rules. Conventionalized metaphors are things like escape from poverty and burden of taxation. For each metaphor, the CCM table contains the metaphorical source domain word (such as escape) the target domain word (such as poverty) and the grammatical construction in which they can be found. The extraction rules operate on the output of a dependency parser and identify the grammatical configurations (such as a verb with a prepositional phrase complement) that are likely to contain conventional metaphors. We present results on detection rates for conventional metaphors and analysis of the similarity and differences of source domains for conventional metaphors in the four languages.","Title: Conference Information Management System: Towards a Personal Assistant System\nYear: 2001\n\nAbstract: We are aiming to develop a personal assistant system which handles its user's files stored in his/her computers and his/her interesting information that can be accessed on the Web. The system categorizes the files and Web pages gathered and extracts information specified by him/her and stores it into a structured database for use as the knowledge of its dialogue module. This paper presents a prototype of the system that handles information about conferences of interest to the user. The system extracts conference names, submission deadlines, dates, URIs and locations from e-mail messages the user has received, and web pages gathered by both crawling and meta-search. Extracted information is stored into a database so that the user can interactively search conference information via a user interface with natural language queries.","Title: Capturing knowledge from domain text with controlled language\nYear: 2005\n\nAbstract: This paper describes a prototype system which captures semantic knowledge from domain text using controlled language. The KANTOO system is used to analyze input sentences from college-level science textbooks, producing sentence-level meaning representations (interlingua). The interlingua expressions are mapped into F-logic statements, which are be stored in a separate knowledge base to support reasoning in the domain.","Title: Language-independent Probabilistic Answer Ranking for Question Answering\nYear: 2007\n\nAbstract: This paper presents a language-independent probabilistic answer ranking framework for question answering. The framework esti- mates the probability of an individual an- swer candidate given the degree of answer relevance and the amount of supporting evi- dence provided in the set of answer candi- dates for the question. Our approach was evaluated by comparing the candidate an- swer sets generated by Chinese and Japanese answer extractors with the re-ranked answer sets produced by the answer ranking frame- work. Empirical results from testing on NT- CIR factoid questions show a 40% perfor- mance improvement in Chinese answer se- lection and a 45% improvement in Japanese answer selection.","Title: Arabic morphology generation using a concatenative strategy\nYear: 2000\n\nAbstract: Arabic inflectional morphology requires infixation, prefixation and suffixation, giving rise to a large space of morphological variation. In this paper we describe an approach to reducing the complexity of Arabic morphology generation using discrimination trees and transformational rules. By decoupling the problem of stem changes from that of prefixes and suffixes, we gain a significant reduction in the number of rules required, as much as a factor of three for certain verb types. We focus on hollow verbs but discuss the wider applicability of the approach.","Title: Diversity-aware evaluation for paraphrase patterns\nYear: 2011\n\nAbstract: Common evaluation metrics for paraphrase patterns do not necessarily correlate with extrinsic recognition task performance. We propose a metric which gives weight to lexical variety in paraphrase patterns; our proposed metric has a positive correlation with paraphrase recognition task performance, with a Pearson correlation of 0.5~0.7 (k=10, with \"strict\" judgment) in a statistically significant level (p-value","Title: Modular Approach to Error Analysis and Evaluation for Multilingual Question Answering\nYear: 2006\n\nAbstract: Multilingual Question Answering systems are generally very complex, integrating several submodules to achieve their result. Global metrics (such as average precision and recall) are insufficient when evaluating the performance of individual submodules and their influence on each other. In this paper, we present a modular approach to error analysis and evaluation; we use manuallyconstructed, goldstandard input for each module to obtain an upperbound for the (local) performance of that module. This approach enables us to identify existing problem areas quickly, and to target improvements accordingly. In this paper, we present a new approach for the evaluation of Multilingual Question Answering (MLQA) systems. Our focus is the JAVELIN MLQA system for factoid questions, which integrates multiple modules in a sequential pipeline with no backtracking or dynamic planning (Lin et al., 2005). The system requires complex integration of several modules. In order to evaluate our system, we analyzed the performance of each module on the evaluation data from the NTCIR CLQA1 task 1 . We created goldstandard data (perfect input) for each module, in order to establish performance upper bounds for each module. Our analysis allows us not only to identify several research issues, but also to compare the performance of our system across different languages (EnglishChinese and EnglishJapanese) on a permodule basis. For evaluating the performance of the same system handling different languages, modular analysis is also useful in identifying languagespecific issues in individual modules. Since our evaluation focuses on the performance of the system, it is a form of informationbased evaluation rather than utilitybased or architectural evaluation (Nyberg & Mitamura, 2002). We adopted a fullyautomatic, informationbased approach to support regular batch evaluation during development and maintenance of the system. 2. Javelin Architecture Our JAVELIN MLQA system consists of five modules: Question Analyzer (QA), Translation Module (TM), Retrieval Strategist (RS), Information eXtractor (IX) and Answer Generator (AG). Input question sentences in English are processed by these modules in the order listed above. The answer candidates are returned in one of the two languages (Japanese and Chinese) as final outputs. The QA module is responsible for parsing the input question, choosing the expected answer type, and producing a set of keywords. The QA module calls the","Title: Zero-Example Event Search using MultiModal Pseudo Relevance Feedback\nYear: 2014\n\nAbstract: We propose a novel method MultiModal Pseudo Relevance Feedback (MMPRF) for event search in video, which requires no search examples from the user. Pseudo Relevance Feedback has shown great potential in retrieval tasks, but previous works are limited to unimodal tasks with only a single ranked list. To tackle the event search task which is inherently multimodal, our proposed MMPRF takes advantage of multiple modalities and multiple ranked lists to enhance event search performance in a principled way. The approach is unique in that it leverages not only semantic features, but also non-semantic low-level features for event search in the absence of training data. Evaluated on the TRECVID MEDTest dataset, the approach improves the baseline by up to 158% in terms of the mean average precision. It also significantly contributes to CMU Team's final submission in TRECVID-13 Multimedia Event Detection.","Title: The KANT system: fast, accurate, high-quality translation in practical domains\nYear: 1992\n\nAbstract: Knowledge-based interlingual machine translation systems produce semantically accurate translations, but typically require massive knowledge acquisition. Ongoing research and development at the Center for Machine Translation has focussed on reducing this requirement to produce large-scale practical applications of knowledge-based MT. This paper describes KANT, the first system to combine principled source language design, semi-automated knowledge acquisition, and knowledge compilation techniques to produce fast, high-quality translation to multiple languages.","Title: Knowledge-based extraction of named entities\nYear: 2002\n\nAbstract: The usual approach to named-entity detection is to learn extraction rules that rely on linguistic, syntactic, or document format patterns that are consistent across a set of documents. However, when there is no consistency among documents, it may be more effective to learn document-specific extraction rules.This paper presents a knowledge-based approach to learning rules for named-entity extraction. Document-specific extraction rules are created using a generate-and-test paradigm and a database of known named-entities. Experimental results show that this approach is effective on Web documents that are difficult for the usual methods.","Title: Hierarchical lexical structure and interpretive mapping in machine translation\nYear: 1992\n\nAbstract: Large-scale knowledge-based machine translation requires significant amounts of lexical knowledge in order to map syntactic structures to conceptual structures. This paper presents a framework in which lexical knowledge is separated into different levels of representation, which are arranged in a hierarchical model based on principles of knowledge representation and lexical semantics. The proposed methodology is language-independent, and has been used to organize lexical knowledge for both English and Japanese.","Title: Challenges in Adapting an Interlingua for Bidirectional English-Italian Translation\nYear: 2000\n\nAbstract: We describe our experience in adapting an existing high-quality, interlingual, unidirectional machine translation system to a new domain and bidirectional translation for a new language pair (English and Italian). We focus on the interlingua design changes which were necessary to achieve high quality output in view of the language mismatches between English and Italian. The representation we propose contains features that are interpreted differently, depending on the translation direction. This decision simplified the process of creating the interlingua for individual sentences, and allows the system to defer mapping of language-specific features (such as tense and aspect), which are realized when the target syntactic feature structure is created. We also describe a set of problems we encountered in translating modal verbs, and discuss the representation of modality in our interlingua.","Title: An Information Repository Model for Advanced Question Answering Systems.\nYear: 2004\n\nAbstract: This paper presents the design and implementation of the information repository which is the central core of the JAVELIN open- domain question answering system. JAVELIN is comprised of several modules that perform a wide variety of question answering (QA) tasks, such as question analysis, document and passage retrieval, answer candidate extraction, answer selection, answer justification, and planning. The architecture is designed to support comparative component-level evaluation, so that different strategies for each module can be integrated and tested in a straightforward way. Each time a module uses a particular piece of information to produce an output, a dependency is created. To support answer justification and introspective learning, the system can use this long- term memory to trace the origin of each answer it produces for a particular question. The JAVELIN Repository implements a complete, consistent relational model for all of the information associated with a question answering scenario.","Title: Extending the self-explanation effect to second language grammar learning\nYear: 2010\n\nAbstract: Self-explanation is an instructional strategy that has shown to be beneficial for math and science learning. However, it remains an open question whether these benefits will extend to other domains like second language grammar learning. Within the domain of the English article system (teaching students when to use a, an, the, or no article at all), we compare two computer-based tutoring conditions in an in vivo classroom study. In the article choice condition, students select the correct article to complete the sentence. In the explanation choice condition, students are given a sentence with the correct article highlighted and choose the rule or feature that best explains the article use. Students (N=101) in both conditions show significant learning on both procedural (article choice) and declarative (explanation choice) tasks. Not surprisingly, we found that declarative instruction (explanation choice) led to significant learning of explanations, while procedural practice (article choice) led to significant learning of the procedures. More interestingly, we also found evidence of cross-type transfer such that declarative practice led to procedural gains and procedural practice led to better understanding of the declarative rules. In general the effects of prompted self-explanation appeared somewhat stronger than those of procedural practice.","Title: Diversifiable Bootstrapping for Acquiring High-Coverage Paraphrase Resource.\nYear: 2012\n\nAbstract: Recognizing similar or close meaning on different surface form is a common challenge in various Natural Language Processing and Information Access applications. However, we identified multiple limitations in existing resources that can be used for solving the vocabulary mismatch problem. To this end, we will propose the Diversifiable Bootstrapping algorithm that can learn paraphrase patterns with a high lexical coverage. The algorithm works in a lightly-supervised iterative fashion, where instance and pattern acquisition are interleaved, each using information provided by the other. By tweaking a parameter in the algorithm, resulting patterns can be diversifiable with a specific degree one can control.","Title: Pronominal anaphora resolution in KANTOO English-to-Spanish machine translation system.\nYear: 2001\n\nAbstract: We describe the automatic resolution of pronominal anaphora using KANT Controlled English (KCE) and the KANTOO English-to-Spanish MT system. Our algorithm is based on a robust, syntax-based approach that applies a set of restrictions and preferences to select the correct antecedent. We report a success rate of 89.6% on a training corpus with 289 anaphors, and 87.5% on held-out data containing 145 anaphors. Resolution of anaphors is important in translation, due to gender mismatches among languages; our approach translates anaphors to Spanish with 97.2% accuracy.","Title: The KANTOO Machine Translation Environment\nYear: 2000\n\nAbstract: In this paper we describe the KANTOO machine translation environment, a set of software services and tools for multilingual document Production. KANTOO includes modules for source language analysis, target language generation, source terminology management, target terminology management, and knowledge source development. The KANTOO system represents a complete re-design and re-implementation of the KANT machine translation system.","Title: Detecting Subevent Structure for Event Coreference Resolution.\nYear: 2014\n\nAbstract: In the task of event coreference resolution, recent work has shown the need to perform not only full coreference but also partial coreference of events. We show that subevents can form a particular hierarchical event structure. This paper examines a novel two-stage approach to finding and improving subevent structures. First, we introduce a multiclass logistic regression model that can detect subevent relations in addition to full coreference. Second, we propose a method to improve subevent structure based on subevent clusters detected by the model. Using a corpus in the Intelligence Community domain, we show that the method achieves over 3.2 BLANC F1 gain in detecting subevent relations against the logistic regression model.","Title: Analogies, explanations, and practice: examining how task types affect second language grammar learning\nYear: 2010\n\nAbstract: Self-explanation is an effective instructional strategy for improving problem solving in math and science domains. However, our previous studies, within the domain of second language grammar learning, show self-explanation to be no more effective than simple practice; perhaps the metalinguistic challenges involved in explaining using one's non-native language are hampering the potential benefits. An alternative strategy is tutoring using analogical comparisons, which reduces language difficulties while continuing to encourage feature focusing and deep processing. In this paper, we investigate adult English language learners learning the English article system (e.g. the difference between “a dog” and “the dog”). We present the results of a classroom-based study (N=99) that compares practice-only to two conditions that facilitate deep processing: self-explanation with practice and analogy with practice. Results show that students in all conditions benefit from the instruction. However, students in the practice-only condition complete the instruction in significantly less time leading to greater learning efficiency. Possible explanations regarding the differences between language and science learning are discussed.","Title: Acquisition of large lexicons for practical knowledge-based MT\nYear: 1994\n\nAbstract: . Although knowledge-based MT systems have the potential to achieve high translationaccuracy, each successful application system requires a large amount of hand-coded lexicalknowledge. Systems like KBMT-89 and its descendents have demonstrated how knowledge-basedtranslation can produce good results in technical domainswith tractable domain semantics. Nevertheless,the magnitude of the development task for large-scale applications with tens of thousandsof domain concepts precludes a purely...","Title: Boiling down information retrieval test collections\nYear: 2010\n\nAbstract: Constructing large-scale test collections is costly and time-consuming, and a few relevance assessment methods have been proposed for constructing \"minimal\" information retrieval test collections that may still provide reliable experimental results. In contrast to building up such test collections, we take existing test collections constructed through the traditional pooling approach and empirically investigate whether they can be \"boiled down.\" More specifically, we report on experiments with test collections from both NT-CIR and TREC to investigate the effect of reducing both the topic set size and the pool depth on the outcome of a statistical significance test between two systems, starting with (approximately) 100 topics and depth-100 pools. We define cost (of manual relevance assessment) as the pool depth multiplied by the topic set size, and error as a system pair whose outcome of statistical significance testing differs from the original result based on the full test collection. Our main findings are: (a) Cost and the number of errors are negatively correlated, and any attempt at substantially reducing cost introduces some errors; (b) The NTCIR-7 IR4QA and the TREC 2004 robust track test collections all yield a comparable and considerable number of errors in response to cost reduction, and this is true despite the fact that the TREC relevance assessments relied on more than twice as many runs as the NTCIR ones; (c) Using 100 topics with depth-30 pools generally yields fewer errors than using 30 topics with depth-100 pools; and (d) Even with depth-100 pools, using fewer than 100 topics results in false alarms, i.e. two systems are declared significantly different even though the full topic set would declare otherwise.","Title: Coping with ambiguity in a large-scale machine translation system\nYear: 1994\n\nAbstract: In an interlingual knowledge-based machine translation system, ambignuity arises when the source language analyzer produces more than one interlingua expression for a source sentence. This can have a negative impact on translation quality, since a target sentence may be produced from an unintended meaning. In this paper we describe the methods used in the KANT machine translation system to reduce or eliminate ambiguity in a large-scale application domain. We also test these methods on a large corpus of test sentences, in order to illustrate how the different disambiguation methods reduce the average number of parses per sentence.","Title: Supervised Within-Document Event Coreference using Information Propagation.\nYear: 2014\n\nAbstract: Event coreference is an important task for full text analysis. However, previous work uses a variety of approaches, sources and evaluation, making the literature confusing and the results incommensurate. We provide a description of the differences to facilitate future research. Second, we present a supervised method for event coreference resolution that uses a rich feature set and propagates information alternatively between events and their arguments, adapting appropriately for each type of argument.","Title: Overview of the NTCIR-8 ACLIA Tasks: Advanced Cross-Lingual Information Access\nYear: 2010\n\nAbstract: paper presents an overview of the ACLIA (Advanced Cross-Lingual Information Access) task cluster at NTCIR-8. The task overview includes: a definition of and motivation for the evaluation; a description of the complex and factoid question types evaluated; the document sources and exchange formats selected and/or defined; the official metrics used in evaluating participant runs; the tools and process used to develop the official evaluation topics; summary data regarding the runs submitted; and the results of evaluating the submitted runs with the official metrics.","Title: Analyzing the Effects of Spoken Dialog Systems on Driving Behavior\nYear: 2006\n\nAbstract: This paper presents an evaluation of a spoken dialog system for automotive environments. Our overall goal was to measure the impact of user-system interaction on the user's driving performance, and to determine whether adding context-awareness to the dialog system might reduce the degree of user distraction during driving. To address this issue, we incorporated context-awareness into a spoken dialog system, and implemented three system features using user context, network context and dialog context. A series of experiments were conducted under three different configurations: driving without a dialog system, driving while using a context-aware dialog system, and driving while using a context-unaware dialog system. We measured the differences between the three configurations by comparing the average car speed, the frequency of speed changes and the angle between the car's direction and the centerline on the road. These results indicate that context-awareness could reduce the degree of user distraction when using a dialog system during driving.","Title: Multimodal knowledge-based analysis in multimedia event detection\nYear: 2012\n\nAbstract: Multimedia Event Detection (MED) is a multimedia retrieval task with the goal of finding videos of a particular event in a large-scale Internet video archive, given example videos and text descriptions. We focus on the multimodal knowledge-based analysis in MED where we utilize meaningful and semantic features such as Automatic Speech Recognition (ASR) transcripts, acoustic concept indexing (i.e. 42 acoustic concepts) and visual semantic indexing (i.e. 346 visual concepts) to characterize videos in archive. We study two scenarios where we either do or do not use the provided example videos. In the former, we propose a novel Adaptive Semantic Similarity (ASS) to measure textual similarity between ASR transcripts of videos. We also incorporate acoustic concept indexing and classification to retrieve test videos, specially with too few spoken words. In the latter 'ad-hoc' scenario where we do not have any example video, we use only the event kit description to retrieve test videos ASR transcripts and visual semantics. We also propose an event-specific fusion scheme to combine textual and visual retrieval outputs. Our results show the effectiveness of the proposed ASS and acoustic concept indexing methods and their complimentary role. We also conduct a set of experiments to assess the proposed framework for the 'ad-hoc' scenario.","Title: Easy Samples First: Self-paced Reranking for Zero-Example Multimedia Search\nYear: 2014\n\nAbstract: Reranking has been a focal technique in multimedia retrieval due to its efficacy in improving initial retrieval results. Current reranking methods, however, mainly rely on the heuristic weighting. In this paper, we propose a novel reranking approach called Self-Paced Reranking (SPaR) for multimodal data. As its name suggests, SPaR utilizes samples from easy to more complex ones in a self-paced fashion. SPaR is special in that it has a concise mathematical objective to optimize and useful properties that can be theoretically verified. It on one hand offers a unified framework providing theoretical justifications for current reranking methods, and on the other hand generates a spectrum of new reranking schemes. This paper also advances the state-of-the-art self-paced learning research which potentially benefits applications in other fields. Experimental results validate the efficacy and the efficiency of the proposed method on both image and video search tasks. Notably, SPaR achieves by far the best result on the challenging TRECVID multimedia event search task.","Title: Text-to-video: a semantic search engine for internet videos\nYear: 2016\n\nAbstract: Abstract Semantic search or text-to-video search in video is a novel and challenging problem in information and multimedia retrieval. Existing solutions are mainly limited to text-to-text matching, in which the query words are matched against the user-generated metadata. This kind of text-to-text search, though simple, is of limited functionality as it provides no understanding about the video content. This paper presents a state-of-the-art system for event search without any user-generated metadata or example videos, known as text-to-video search. The system relies on substantial video content understanding and allows for searching complex events over a large collection of videos. The proposed text-to-video search can be used to augment the existing text-to-text search for video. The novelty and practicality are demonstrated by the evaluation in NIST TRECVID 2014, where the proposed system achieves the best performance. We share our observations and lessons in building such a state-of-the-art system, which may be instrumental in guiding the design of the future system for video search and analysis.","Title: JAVELIN III: Cross-Lingual Question Answering from Japanese and Chinese Documents\nYear: 2007\n\nAbstract: In this paper, we describe the JAVELIN Cross Language Question Answering system, which includes modules for question analysis, keyword translation, document retrieval, information extraction and answer generation. In the NTCIR6 CLQA2 evaluation, our system achieved 19% and 13% accuracy in the English-to-Chinese and English-to-Japanese subtasks, respectively. An overall analysis and a detailed module-by-module analysis are presented.","Title: JAVELIN III: Answering Non-Factoid Questions in Japanese\nYear: 2007\n\nAbstract: In this paper, we describe our adaptation of the JAVELIN system to Japanese question answering for the NTCIR-6 QAC track. To establish a baseline Japanese-to-Japanese non-factoid question answering system, we performed the minimum extensions to our factoid question answering system. The answer boundary recognition task was simplified by introducing a \u001cone sentence assumption \u001d in the answer extraction phase. In the end, the performance of our machine learning-based sub-modules was affected by a scarcity of training data; nevertheless, our system performed close to the average accuracy in the number of questions correctly answered.","Title: Overview of the NTCIR-7 ACLIA IR4QA Task\nYear: 2008\n\nAbstract: This paper presents an overview of the IR4QA (In- formation Retrieval for Question Answering) Task of the NTCIR-7 ACLIA (Advanced Cross-lingual Infor- mation Access) Task Cluster. IR4QA evaluates tra- ditional ranked retrieval of documents using well- studied metrics such as Average Precision, but the re- trieval task is embedded in the context of cross-lingual question answering. That is, document retrieval is treated as a component of the entire question answer- ing system. This paper concentrates on how rele- vance assessments for the Simpified Chinese, Tradi- tional Chinese and Japanese IR4QA test collections were obtained, and the outcome of the formal IR4QA evaluation using the three collections. For the rela- tionship between IR4QA and the entire ACLIA task cluster, we refer the reader to the overview paper of ACLIA (17). For details of the individual IR4QA sys- tems, we refer the reader to the participants' reports.","Title: Query Expansion and Machine Translation for Robust Cross-Lingual Information Retrieval\nYear: 2008\n\nAbstract: In this paper, we describe the Information Retrieval subsystem of JAVELIN IV, a question-answering system that answers complex questions from multilingual sources. Our research focus is on different strategies for query term extraction, translation, filtering, expansion and weighting, including a novel alias expansion technique using lexico-syntactic patterns learned with weakly-supervised algorithm. In the NTCIR7 IR4QA evaluation, our retrieval system achieved 59% and 59% MAP in the Chinese-to-Chinese and Japanese-to- Japanese subtasks, respectively. We provide a rationale for the retrieval system design, and present a detailed error analysis for our formal run results.","Title: Complex Cross-lingual Question Answering as a Sequential Classification and Multi-Document Summarization Task\nYear: 2008\n\nAbstract: In this paper, we describe the JAVELIN IV system, which treats complex question answering as a sequential classification and multi-document summarization task. Our research and development effort is based on various forms of linguistic annotation, and a comparison of various answer extraction and summarization algorithms. We discuss the use of different units of extraction, the effect of different syntactic features for classification, and the effect of different summarization strategies. We also analyze how the performance of machine translation and information retrieval affect the performance of question answering. In the NTCIR-7 CCLQA main track official evaluation, our system achieved 16.3% and 19.2% accuracy in the English-to- Japanese and English-to-Chinese subtasks, respectively.","Title: Bootstrap Pattern Learning for Open-Domain CLQA*.\nYear: 2010\n\nAbstract: We describe Javelin, a Cross-lingual Question Answering system which participated in the NTCIR-8 ACLIA evaluation and which is designed to work on any type of question, including factoid and complex questions. The key technical contribution of this paper is a minimally supervised bootstrapping approach to generating lexico- syntactic patterns used for answer extraction. The preliminary evaluation result (measured by nugget F3 score) shows that the proposed pattern learning approach outperformed two baselines, a supervised learning approach used in NTCIR-7 ACLIA and a simple key-term based approach, for both monolingual and crosslingual tracks. The proposed approach is general and thus it has potential applicability to a wide variety of information access applications which require deeper semantic processing. Keywordslearning, minimally-supervised learning, bootstrapping.","Title: CMU JAVELIN System for NTCIR5 CLQA1\nYear: 2005\n\nAbstract: In this paper, we describe the JAVELIN Cross Lan- guage Question Answering system, which includes modules for question analysis, keyword translation, document retrieval, information extraction and an- swer generation. In the NTCIR5 CLQA1 evaluation, our system achieved 7.5% and 10.0% accuracy in the English-to-Chinese and English-to-Japanese sub- tasks, respectively. An overall analysis and a detailed module-by-module analysis are presented.","Title: Fast and Accurate Content-based Semantic Search in 100M Internet Videos\nYear: 2015\n\nAbstract: Large-scale content-based semantic search in video is an interesting and fundamental problem in multimedia analysis and retrieval. Existing methods index a video by the raw concept detection score that is dense and inconsistent, and thus cannot scale to \\\"big data\\\" that are readily available on the Internet. This paper proposes a scalable solution. The key is a novel step called concept adjustment that represents a video by a few salient and consistent concepts that can be efficiently indexed by the modified inverted index. The proposed adjustment model relies on a concise optimization framework with interpretations. The proposed index leverages the text-based inverted index for video retrieval. Experimental results validate the efficacy and the efficiency of the proposed method. The results show that our method can scale up the semantic search while maintaining state-of-the-art search performance. Specifically, the proposed method (with reranking) achieves the best result on the challenging TRECVID Multimedia Event Detection (MED) zero-example task. It only takes 0.2 second on a single CPU core to search a collection of 100 million Internet videos.","Title: Bridging the Ultimate Semantic Gap: A Semantic Search Engine for Internet Videos\nYear: 2015\n\nAbstract: Semantic search in video is a novel and challenging problem in information and multimedia retrieval. Existing solutions are mainly limited to text matching, in which the query words are matched against the textual metadata generated by users. This paper presents a state-of-the-art system for event search without any textual metadata or example videos. The system relies on substantial video content understanding and allows for semantic search over a large collection of videos. The novelty and practicality is demonstrated by the evaluation in NIST TRECVID 2014, where the proposed system achieves the best performance. We share our observations and lessons in building such a state-of-the-art system, which may be instrumental in guiding the design of the future system for semantic search in video.","Title: SIGIR 2017 Workshop on Open Knowledge Base and Question Answering (OKBQA2017)\nYear: 2017\n\nAbstract: Over the past years, several challenges and calls for research projects have pointed out the dire need for pushing natural language interfaces. In this context, the importance of Semantic Web data as a premier knowledge source is rapidly increasing. But we are still far from having accurate natural language interfaces that allow handling complex information needs in a user-centric and highly performant manner. The development of such interfaces requires collaboration of a range of different fields, including natural language processing, information extraction, knowledge base construction and population, reasoning, and question answering. With the goal to join forces in the collaborative development of natural language QA systems, the second OKBQA workshop is organized within the 40th SIGIR conference.","Title: Event Nugget and Event Coreference Annotation.\nYear: 2016\n\nAbstract: In this paper, we describe the event nugget annotation created in support of the pilot Event Nugget Detection evaluation in 2014 and in support of the Event Nugget Detection and Coreference open evaluation in 2015, which was one of the Knowledge Base Population tracks within the NIST Text Analysis Conference. We present the data volume annotated for both training and evaluation data for the 2015 evaluation as well as changes to annotation in 2015 as compared to that of 2014. We also analyze the annotation for the 2015 evaluation as an example to show the annotation challenges and consistency, and identify the event types and subtypes that are most difficult for human annotators. Finally, we discuss annotation issues that we need to take into consideration in the future.","Title: The ARIEL-CMU situation frame detection pipeline for LoReHLT16: a model translation approach.\nYear: 2018\n\nAbstract: The LoReHLT16 evaluation challenged participants to extract Situation Frames (SFs)—structured descriptions of humanitarian need situations—from monolingual Uyghur text. The ARIEL-CMU SF detector combines two classification paradigms, a manually curated keyword-spotting system and a machine learning classifier. These were applied by translating the models on a per-feature basis, rather than translating the input text. The resulting combined model provides the accuracy of human insight with the generality of machine learning, and is relatively tractable to human analysis and error correction. Other factors contributing to success were automatic dictionary creation, the use of phonetic transcription, detailed, hand-written morphological analysis, and naturalistic glossing for error analysis by humans. The ARIEL-CMU SF pipeline produced the top-scoring LoReHLT16 situation frame detection systems for the metrics SFType, SFType+Place+Need, SFType+Place+Relief, and SFType+Place+Urgency, at each of the three checkpoints.","Title: BioAMA: Towards an End to End BioMedical Question Answering System.\nYear: 2018\n\nAbstract: In this paper, we present a novel Biomedical Question Answering system, BioAMA: \"Biomedical Ask Me Anything\" on task 5b of the annual BioASQ challenge (Balikas et al., 2015). We focus on a wide variety of question types including factoid, list based, summary and yes/no type questions that generate both exact and well-formed 'ideal' answers. For summary-type questions, we combine effective IR-based techniques for retrieval and diversification of relevant snippets for a question to create an end-to-end system which achieves a ROUGE-2 score of 0.72 and a ROUGE-SU4 score of 0.71 on ideal answer questions (7% improvement over the previous best model). Additionally, we propose a novel Natural Language Inference (NLI) based framework to answer the yes/no questions. To train the NLI model, we also devise a transfer-learning technique by cross-domain projection of word embeddings. Finally, we present a two-stage approach to address the factoid and list type questions by first generating a candidate set using NER taggers and ranking them using both supervised and unsupervised techniques.","Title: Graph Based Decoding for Event Sequencing and Coreference Resolution.\nYear: 2018\n\nAbstract: Events in text documents are interrelated in complex ways. In this paper, we study two types of relation: Event Coreference and Event Sequencing. We show that the popular tree-like decoding structure for automated Event Coreference is not suitable for Event Sequencing. To this end, we propose a graph-based decoding algorithm that is applicable to both tasks. The new decoding algorithm supports flexible feature sets for both tasks. Empirically, our event coreference system has achieved state-of-the-art performance on the TAC-KBP 2015 event coreference task and our event sequencing system beats a strong temporal-based, oracle-informed baseline. We discuss the challenges of studying these event relations.","Title: Automatic Event Salience Identification.\nYear: 2018\n\nAbstract: Identifying the salience (i.e. importance) of discourse units is an important task in language understanding. While events play important roles in text documents, little research exists on analyzing their saliency status. This paper empirically studies the Event Salience task and proposes two salience detection models based on content similarities and discourse relations. The first is a feature based salience model that incorporates similarities among discourse units. The second is a neural model that captures more complex relations between discourse units. Tested on our new large-scale event salience corpus, both methods significantly outperform the strong frequency baseline, while our neural model further improves the feature based one by a large margin. Our analyses demonstrate that our neural model captures interesting connections between salience and discourse unit relations (e.g., scripts and frame structures).","Title: Correction grammars for error handling in a speech dialog system\nYear: 2004\n\nAbstract: Speech recognition errors are inevitable in a speech dialog system. This paper presents an error handling method based on correction grammars which recognize the correction utterances which follow a recognition error. Correction grammars are dynamically created from existing grammars and a set of correction templates. We also describe a prototype dialog system which incorporates this error handling method, and provide empirical evidence that this method can improve dialog success rate and reduce the number of dialog turns required for error recovery.","Title: The ARIEL-CMU Systems for LoReHLT18.\nYear: 2019\n\nAbstract: This paper describes the ARIEL-CMU submissions to the Low Resource Human Language Technologies (LoReHLT) 2018 evaluations for the tasks Machine Translation (MT), Entity Discovery and Linking (EDL), and detection of Situation Frames in Text and Speech (SF Text and Speech).","Title: Retrieve, Caption, Generate: Visual Grounding for Enhancing Commonsense in Text Generation Models.\nYear: 2022\n\nAbstract: We investigate the use of multimodal information contained in images as an effective method for enhancing the commonsense of Transformer models for text generation. We perform experiments using BART and T5 on concept-to-text generation, specifically the task of generative commonsense reasoning, or CommonGen. We call our approach VisCTG: Visually Grounded Concept-to-Text Generation. VisCTG involves captioning images representing appropriate everyday scenarios, and using these captions to enrich and steer the generation process. Comprehensive evaluation and analysis demonstrate that VisCTG noticeably improves model performance while successfully addressing several issues of the baseline generations, including poor commonsense, fluency, and specificity.","Title: Cross-document Event Identity via Dense Annotation.\nYear: 2021\n\nAbstract: In this paper, we study the identity of textual events from different documents. While the complex nature of event identity is previously studied (Hovy et al., 2013), the case of events across documents is unclear. Prior work on cross-document event coreference has two main drawbacks. First, they restrict the annotations to a limited set of event types. Second, they insufficiently tackle the concept of event identity. Such annotation setup reduces the pool of event mentions and prevents one from considering the possibility of quasi-identity relations. We propose a dense annotation approach for cross-document event coreference, comprising a rich source of event mentions and a dense annotation effort between related document pairs. To this end, we design a new annotation workflow with careful quality control and an easy-to-use annotation interface. In addition to the links, we further collect overlapping event contexts, including time, location, and participants, to shed some light on the relation between identity decisions and context. We present an open-access dataset for cross-document event coreference, CDEC-WN, collected from English Wikinews and open-source our annotation toolkit to encourage further research on cross-document tasks.","Title: R3: Refined Retriever-Reader Pipeline for Multidoc2dial\nYear: 2022\n\nAbstract: In this paper, we present our submission to the DialDoc shared task based on the Multi-Doc2Dial dataset. MultiDoc2Dial is a conversational question answering dataset that grounds dialogues in multiple documents. The task involves grounding a user's query in a document followed by generating an appropriate response. We propose several improvements over the baseline's retriever-reader architecture to aid in modeling goal-oriented dialogues grounded in multiple documents. Our proposed approach employs sparse representations for passage retrieval, a passage re-ranker, the fusion-in-decoder architecture for generation, and a curriculum learning training paradigm. Our approach shows a 12 point improvement in BLEU score compared to the baseline RAG model.","Title: GSRFormer: Grounded Situation Recognition Transformer with Alternate Semantic Attention Refinement\nYear: 2022\n\nAbstract: ABSTRACTGrounded Situation Recognition (GSR) aims to generate structured semantic summaries of images for \"human-like'' event understanding. Specifically, GSR task not only detects the salient activity verb (e.g. buying), but also predicts all corresponding semantic roles (e.g. agent and goods). Inspired by object detection and image captioning tasks, existing methods typically employ a two-stage framework: 1) detect the activity verb, and then 2) predict semantic roles based on the detected verb. Obviously, this illogical framework constitutes a huge obstacle to semantic understanding. First, pre-detecting verbs solely without semantic roles inevitably fails to distinguish many similar daily activities (e.g., offering and giving, buying and selling). Second, predicting semantic roles in a closed auto-regressive manner can hardly exploit the semantic relations among the verb and roles. To this end, in this paper we propose a novel two-stage framework that focuses on utilizing such bidirectional relations within verbs and roles. In the first stage, instead of pre-detecting the verb, we postpone the detection step and assume a pseudo label, where an intermediate representation for each corresponding semantic role is learned from images. In the second stage, we exploit transformer layers to unearth the potential semantic relations within both verbs and semantic roles. With the help of a set of support images, an alternate learning scheme is designed to simultaneously optimize the results: update the verb using nouns corresponding to the image, and update nouns using verbs from support images. Extensive experimental results on challenging SWiG benchmarks show that our renovated framework outperforms other state-of-the-art methods under various metrics."],"string":"[\n \"Title: Source language diagnostics for MT.\\nYear: 2003\\n\\nAbstract: This paper presents a source language diagnostic system for controlled translation. Diagnostics were designed and implemented to address the most difficult rewrites for authors, based on an empirical analysis of log files containing over 180,000 sentences. The design and implementa- tion of the diagnostic system are presented, along with experimental results from an empirical evaluation of the completed system. We found that the diagnostic system can correctly identify the problem in 90.2% of the cases. In addition, depending on the type of grammar problem, the diagnostic system may offer a rewritten sentence. We found that 89.4% of the rewritten sentences were correctly rewritten. The results suggest that these methods could be used as the basis for an automatic rewriting system in the future.\",\n \"Title: Lexicons\\nYear: 1989\\n\\nAbstract: The three lexicons used by KBMT-89 are described: A concept lexicon constitutes the sublanguage domain model for specifying semantic information; it is maintained by Ontos, a knowledge-acquisition and maintenance system. An analysis lexicon is a dictionary containing syntactic information and mapping rules required for semantic parsing. And a generation lexicon, similar to the analysis lexicon, is employed in the generation phase.\",\n \"Title: Analysis and generation grammars\\nYear: 1989\\n\\nAbstract: This paper describes the analysis and generation grammars for English and Japanese as they were employed in the KBMT-89 program. We discuss word order, coordination, subcategorization, morphological rules, rule ordering and bi-directional grammars.\",\n \"Title: A fast, accurate deterministic parser for Chinese\\nYear: 2006\\n\\nAbstract: We present a novel classifier-based deterministic parser for Chinese constituency parsing. Our parser computes parse trees from bottom up in one pass, and uses classifiers to make shift-reduce decisions. Trained and evaluated on the standard training and test sets, our best model (using stacked classifiers) runs in linear time and has labeled precision and recall above 88% using gold-standard part-of-speech tags, surpassing the best published results. Our SVM parser is 2-13 times faster than state-of-the-art parsers, while producing more accurate results. Our Maxent and DTree parsers run at speeds 40-270 times faster than state-of-the-art parsers, but with 5-6% losses in accuracy.\",\n \"Title: Robust Speech Dialog Interface For Car Telematics Service\\nYear: 2004\\n\\nAbstract: In this paper, we describe new consumer services based on speech processing technologies to support a new digital/mobile era of ubiquitous communication. First, we propose a compact and noise robust embedded speech recognition middleware implemented on microprocessors focused on sophisticated HMIs (Human Machine Interfaces) for car information systems (i.e. Car Telematics). Second, we report on a novel and sophisticated Dialog Management/Manager (DM) system based on VoiceXML (Voice eXtensible Markup Language), called CAMMIA (Conversational Agent for Multimedia Mobile Information Access). The proposed DM will handle two important issues: an automatic generation scheme for lexicons and grammars, and an effective combination/merger between Automatic Speech Recognition (ASR) and Natural Language Processing (NLP). The new DM scheme has been evaluated for an application of the Car Telematics service task after integration with ASR and a VoiceXML interpreter (VXI).\",\n \"Title: Parallel Syntactic Annotation of Multiple Languages\\nYear: 2006\\n\\nAbstract: This paper describes an effort to investigate the incrementally deepening development of an interlingua notation, validated by human annotation of texts in English plus six languages. We begin with deep syntactic annotation, and in this paper present a series of annotation manuals for six different languages at the deep-syntactic level of representation. Many syntactic differences between languages are removed in the proposed syntactic annotation, making them useful resources for multilingual NLP projects with semantic components.\",\n \"Title: Deriving Semantic Knowledge from Descriptive Texts Using an MT System\\nYear: 2002\\n\\nAbstract: This paper describes the results of a feasibility study which focused on deriving semantic networks from descriptive texts using controlled language. The KANT system [3,6] was used to analyze input paragraphs, producing sentence-level interlingua representations. The interlinguas were merged to construct a paragraph-level representation, which was used to create a semantic network in Conceptual Graph (CG) [1] format. The interlinguas are also translated (using the KANTOO generator) into OWL statements for entry into the Ontology Works electrical power factbase [9]. The system was extended to allow simple querying in natural language.\",\n \"Title: The JAVELIN Question-Answering System at TREC 2003: A Multi-Strategh Approach with Dynamic Planning\\nYear: 2003\\n\\nAbstract: The JAVELIN system evaluated at TREC 2003 is an integrated architecture for open-domain question answering. JAVELIN employs a mod- ular approach that addresses individual aspects of the QA task in an abstract manner. The Sys- tem implements a planner that controls the ex- ecution and information flow, as well as a mul- tiple answer seeking strategies used differently depending on the type of question.\",\n \"Title: Controlled language for multilingual machine translation.\\nYear: 1999\\n\\nAbstract: In this paper, we present an overview of the issues in designing a controlled language, the implementation of a controlled language checker, and the deployment of KANT Con- trolled English for multilingual machine translation. We also discuss some success criteria for introducing controlled language. Finally, future vision of KANT controlled language development is discussed.\",\n \"Title: An English-to-Turkish Interlingual MT System\\nYear: 1998\\n\\nAbstract: This paper describes the integration of a Turkish generation system with the KANT knowledge-based machine translation system to produce a prototype English-Turkish interlingua-based machine translation system. These two independently constructed systems were successfully integrated within a period of two months, through development of a module which maps KANT interlingua expressions to Turkish syntactic structures. The combined system is able to translate completely and correctly 44 of 52 benchmark sentences in the domain of broadcast news captions. This study is the first known application of knowledge-based machine translation from English to Turkish, and our initial results show promise for future development.\",\n \"Title: Probabilistic models for answer-ranking in multilingual question-answering\\nYear: 2010\\n\\nAbstract: This article presents two probabilistic models for answering ranking in the multilingual question-answering (QA) task, which finds exact answers to a natural language question written in different languages. Although some probabilistic methods have been utilized in traditional monolingual answer-ranking, limited prior research has been conducted for answer-ranking in multilingual question-answering with formal methods. This article first describes a probabilistic model that predicts the probabilities of correctness for individual answers in an independent way. It then proposes a novel probabilistic method to jointly predict the correctness of answers by considering both the correctness of individual answers as well as their correlations. As far as we know, this is the first probabilistic framework that proposes to model the correctness and correlation of answer candidates in multilingual question-answering and provide a novel approach to design a flexible and extensible system architecture for answer selection in multilingual QA. An extensive set of experiments were conducted to show the effectiveness of the proposed probabilistic methods in English-to-Chinese and English-to-Japanese cross-lingual QA, as well as English, Chinese, and Japanese monolingual QA using TREC and NTCIR questions.\",\n \"Title: Automatic collocation suggestion in academic writing\\nYear: 2010\\n\\nAbstract: In recent years, collocation has been widely acknowledged as an essential characteristic to distinguish native speakers from non-native speakers. Research on academic writing has also shown that collocations are not only common but serve a particularly important discourse function within the academic community. In our study, we propose a machine learning approach to implementing an online collocation writing assistant. We use a data-driven classifier to provide collocation suggestions to improve word choices, based on the result of classification. The system generates and ranks suggestions to assist learners' collocation usages in their academic writing with satisfactory results.\",\n \"Title: Interlingual annotation of parallel text corpora: A new framework for annotation and evaluation\\nYear: 2010\\n\\nAbstract: This paper focuses on an important step in the creation of a system of meaning representation and the development of semantically annotated parallel corpora, for use in applications such as machine translation, question answering, text summarization, and information retrieval. The work described below constitutes the first effort of any kind to annotate multiple translations of foreign-language texts with interlingual content. Three levels of representation are introduced: deep syntactic dependencies (IL0), intermediate semantic representations (IL1), and a normalized representation that unifies conversives, nonliteral language, and paraphrase (IL2). The resulting annotated, multilingually induced, parallel corpora will be useful as an empirical basis for a wide range of research, including the development and evaluation of interlingual NLP systems and paraphrase-extraction systems as well as a host of other research and development efforts in theoretical and applied linguistics, foreign language pedagogy, translation studies, and other related disciplines.\",\n \"Title: Effects of adaptive prompted self-explanation on robust learning of second language grammar\\nYear: 2011\\n\\nAbstract: Prompted self-explanation is a successful intervention for many domains. However, in our previous work within the domain of second language grammar learning, we found no advantage for self-explanation over practice alone. Here, we continue testing the generality of self-explanation through the development of an adaptive self-explanation tutor and report on results of a classroom evaluation (N=92) in which we compare the adaptive tutor to a practice-only tutor. We investigate both procedural and declarative knowledge acquisition as well as long-term retention. Results show that while self-explanation takes more time than practice alone, it leads to greater learning of declarative knowledge. However, there are no differences between conditions on immediate or long-term retention measures of procedural knowledge.\",\n \"Title: The JAVELIN Question-Answering System at TREC 2002\\nYear: 2002\\n\\nAbstract: This paper describes the JAVELIN approach for open-domain question answering (Justification-based AnswerValuation through Language Interpretation), and our participation in the TREC 2002 question-answeringtrack. The main scientific tenets underlying JAVELIN are:QA as Planning. Question Answering is a complex multi-faceted task, where question type, informationavailability, user needs, and NLP sophistication of QA modules all combine dynamically to determine the optimal QA strategy....\",\n \"Title: GE-CMU: description of the SHOGUN system used for MUC-5\\nYear: 1993\\n\\nAbstract: This paper describes the GE-CMU TIPSTER/SHOGUN system as configured for the TIP-STER 24-month (MUC-5) benchmark, and gives details of the system's performance on the selected Japanese and English texts. The SHOGUN system is a distillation of some of the key ideas that emerged from previous benchmarks and experiments, emphasizing a simple architecture in which the focus is on detailed corpus-based knowledge. This design allowed the project to meet its goal of achieving advances in coverage and accuracy while showing consistently good performance across languages and domains.\",\n \"Title: Interlingual Annotation for MT Development\\nYear: 2004\\n\\nAbstract: MT systems that use only superficial representations, including the current generation of statistical MT systems, have been successful and useful. However, they will experience a plateau in quality, much like other \\\"silver bullet\\\" approaches to MT. We pursue work on the development of interlingual representations for use in symbolic or hybrid MT systems. In this paper, we describe the creation of an interlingua and the development of a corpus of semantically annotated text, to be validated in six languages and evaluated in several ways. We have established a distributed, well-functioning research methodology, designed a preliminary interlingua notation, created annotation manuals and tools, developed a test collection in six languages with associated English translations, annotated some 150 translations, and designed and applied various annotation metrics. We describe the data sets being annotated and the interlingual (IL) representation language which uses two ontologies and a systematic theta-role list. We present the annotation tools built and outline the annotation process. Following this, we describe our evaluation methodology and conclude with a summary of issues that have arisen.\",\n \"Title: Evaluating Textual Entailment Recognition for University Entrance Examinations\\nYear: 2012\\n\\nAbstract: The present article addresses an attempt to apply questions in university entrance examinations to the evaluation of textual entailment recognition. Questions in several fields, such as history and politics, primarily test the examinee’s knowledge in the form of choosing true statements from multiple choices. Answering such questions can be regarded as equivalent to finding evidential texts from a textbase such as textbooks and Wikipedia. Therefore, this task can be recast as recognizing textual entailment between a description in a textbase and a statement given in a question. We focused on the National Center Test for University Admission in Japan and converted questions into the evaluation data for textual entailment recognition by using Wikipedia as a textbase. Consequently, it is revealed that nearly half of the questions can be mapped into textual entailment recognition; 941 text pairs were created from 404 questions from six subjects. This data set is provided for a subtask of NTCIR RITE (Recognizing Inference in Text), and 16 systems from six teams used the data set for evaluation. The evaluation results revealed that the best system achieved a correct answer ratio of 56%, which is significantly better than a random choice baseline.\",\n \"Title: Keyword Translation from English to Chinese for Multilingual QA\\nYear: 2004\\n\\nAbstract: The Keyword Translator is a part of the Question Analyzer module in the JAVELIN Question-Answering system; it translates the keywords, which are used to query documents and extract answers, from one language to another. Much work has been in the area of query translation for CLIR or MLIR, however, many have focused on methods using hard-to-obtain and domain-specific resources, and evaluation is often based on retrieval performance rather than translation correctness. In this paper we will describe methods combining easily accessible, general-purpose MT systems to improve keyword translation correctness. We also describe methods that utilize the question sentence available to a question-answering system to improve translation correctness. We will show that using multiple MT systems and the question sentence to translate keywords from English to Mandarin Chinese can significantly improve keyword translation correctness.\",\n \"Title: Resources for the Detection of Conventionalized Metaphors in Four Languages.\\nYear: 2014\\n\\nAbstract: This paper describes a suite of tools for extracting conventionalized metaphors in English, Spanish, Farsi, and Russian. The method depends on three significant resources for each language: a corpus of conventionalized metaphors, a table of conventionalized conceptual metaphors (CCM table), and a set of extraction rules. Conventionalized metaphors are things like escape from poverty and burden of taxation. For each metaphor, the CCM table contains the metaphorical source domain word (such as escape) the target domain word (such as poverty) and the grammatical construction in which they can be found. The extraction rules operate on the output of a dependency parser and identify the grammatical configurations (such as a verb with a prepositional phrase complement) that are likely to contain conventional metaphors. We present results on detection rates for conventional metaphors and analysis of the similarity and differences of source domains for conventional metaphors in the four languages.\",\n \"Title: Conference Information Management System: Towards a Personal Assistant System\\nYear: 2001\\n\\nAbstract: We are aiming to develop a personal assistant system which handles its user's files stored in his/her computers and his/her interesting information that can be accessed on the Web. The system categorizes the files and Web pages gathered and extracts information specified by him/her and stores it into a structured database for use as the knowledge of its dialogue module. This paper presents a prototype of the system that handles information about conferences of interest to the user. The system extracts conference names, submission deadlines, dates, URIs and locations from e-mail messages the user has received, and web pages gathered by both crawling and meta-search. Extracted information is stored into a database so that the user can interactively search conference information via a user interface with natural language queries.\",\n \"Title: Capturing knowledge from domain text with controlled language\\nYear: 2005\\n\\nAbstract: This paper describes a prototype system which captures semantic knowledge from domain text using controlled language. The KANTOO system is used to analyze input sentences from college-level science textbooks, producing sentence-level meaning representations (interlingua). The interlingua expressions are mapped into F-logic statements, which are be stored in a separate knowledge base to support reasoning in the domain.\",\n \"Title: Language-independent Probabilistic Answer Ranking for Question Answering\\nYear: 2007\\n\\nAbstract: This paper presents a language-independent probabilistic answer ranking framework for question answering. The framework esti- mates the probability of an individual an- swer candidate given the degree of answer relevance and the amount of supporting evi- dence provided in the set of answer candi- dates for the question. Our approach was evaluated by comparing the candidate an- swer sets generated by Chinese and Japanese answer extractors with the re-ranked answer sets produced by the answer ranking frame- work. Empirical results from testing on NT- CIR factoid questions show a 40% perfor- mance improvement in Chinese answer se- lection and a 45% improvement in Japanese answer selection.\",\n \"Title: Arabic morphology generation using a concatenative strategy\\nYear: 2000\\n\\nAbstract: Arabic inflectional morphology requires infixation, prefixation and suffixation, giving rise to a large space of morphological variation. In this paper we describe an approach to reducing the complexity of Arabic morphology generation using discrimination trees and transformational rules. By decoupling the problem of stem changes from that of prefixes and suffixes, we gain a significant reduction in the number of rules required, as much as a factor of three for certain verb types. We focus on hollow verbs but discuss the wider applicability of the approach.\",\n \"Title: Diversity-aware evaluation for paraphrase patterns\\nYear: 2011\\n\\nAbstract: Common evaluation metrics for paraphrase patterns do not necessarily correlate with extrinsic recognition task performance. We propose a metric which gives weight to lexical variety in paraphrase patterns; our proposed metric has a positive correlation with paraphrase recognition task performance, with a Pearson correlation of 0.5~0.7 (k=10, with \\\"strict\\\" judgment) in a statistically significant level (p-value\",\n \"Title: Modular Approach to Error Analysis and Evaluation for Multilingual Question Answering\\nYear: 2006\\n\\nAbstract: Multilingual Question Answering systems are generally very complex, integrating several submodules to achieve their result. Global metrics (such as average precision and recall) are insufficient when evaluating the performance of individual submodules and their influence on each other. In this paper, we present a modular approach to error analysis and evaluation; we use manuallyconstructed, goldstandard input for each module to obtain an upperbound for the (local) performance of that module. This approach enables us to identify existing problem areas quickly, and to target improvements accordingly. In this paper, we present a new approach for the evaluation of Multilingual Question Answering (MLQA) systems. Our focus is the JAVELIN MLQA system for factoid questions, which integrates multiple modules in a sequential pipeline with no backtracking or dynamic planning (Lin et al., 2005). The system requires complex integration of several modules. In order to evaluate our system, we analyzed the performance of each module on the evaluation data from the NTCIR CLQA1 task 1 . We created goldstandard data (perfect input) for each module, in order to establish performance upper bounds for each module. Our analysis allows us not only to identify several research issues, but also to compare the performance of our system across different languages (EnglishChinese and EnglishJapanese) on a permodule basis. For evaluating the performance of the same system handling different languages, modular analysis is also useful in identifying languagespecific issues in individual modules. Since our evaluation focuses on the performance of the system, it is a form of informationbased evaluation rather than utilitybased or architectural evaluation (Nyberg & Mitamura, 2002). We adopted a fullyautomatic, informationbased approach to support regular batch evaluation during development and maintenance of the system. 2. Javelin Architecture Our JAVELIN MLQA system consists of five modules: Question Analyzer (QA), Translation Module (TM), Retrieval Strategist (RS), Information eXtractor (IX) and Answer Generator (AG). Input question sentences in English are processed by these modules in the order listed above. The answer candidates are returned in one of the two languages (Japanese and Chinese) as final outputs. The QA module is responsible for parsing the input question, choosing the expected answer type, and producing a set of keywords. The QA module calls the\",\n \"Title: Zero-Example Event Search using MultiModal Pseudo Relevance Feedback\\nYear: 2014\\n\\nAbstract: We propose a novel method MultiModal Pseudo Relevance Feedback (MMPRF) for event search in video, which requires no search examples from the user. Pseudo Relevance Feedback has shown great potential in retrieval tasks, but previous works are limited to unimodal tasks with only a single ranked list. To tackle the event search task which is inherently multimodal, our proposed MMPRF takes advantage of multiple modalities and multiple ranked lists to enhance event search performance in a principled way. The approach is unique in that it leverages not only semantic features, but also non-semantic low-level features for event search in the absence of training data. Evaluated on the TRECVID MEDTest dataset, the approach improves the baseline by up to 158% in terms of the mean average precision. It also significantly contributes to CMU Team's final submission in TRECVID-13 Multimedia Event Detection.\",\n \"Title: The KANT system: fast, accurate, high-quality translation in practical domains\\nYear: 1992\\n\\nAbstract: Knowledge-based interlingual machine translation systems produce semantically accurate translations, but typically require massive knowledge acquisition. Ongoing research and development at the Center for Machine Translation has focussed on reducing this requirement to produce large-scale practical applications of knowledge-based MT. This paper describes KANT, the first system to combine principled source language design, semi-automated knowledge acquisition, and knowledge compilation techniques to produce fast, high-quality translation to multiple languages.\",\n \"Title: Knowledge-based extraction of named entities\\nYear: 2002\\n\\nAbstract: The usual approach to named-entity detection is to learn extraction rules that rely on linguistic, syntactic, or document format patterns that are consistent across a set of documents. However, when there is no consistency among documents, it may be more effective to learn document-specific extraction rules.This paper presents a knowledge-based approach to learning rules for named-entity extraction. Document-specific extraction rules are created using a generate-and-test paradigm and a database of known named-entities. Experimental results show that this approach is effective on Web documents that are difficult for the usual methods.\",\n \"Title: Hierarchical lexical structure and interpretive mapping in machine translation\\nYear: 1992\\n\\nAbstract: Large-scale knowledge-based machine translation requires significant amounts of lexical knowledge in order to map syntactic structures to conceptual structures. This paper presents a framework in which lexical knowledge is separated into different levels of representation, which are arranged in a hierarchical model based on principles of knowledge representation and lexical semantics. The proposed methodology is language-independent, and has been used to organize lexical knowledge for both English and Japanese.\",\n \"Title: Challenges in Adapting an Interlingua for Bidirectional English-Italian Translation\\nYear: 2000\\n\\nAbstract: We describe our experience in adapting an existing high-quality, interlingual, unidirectional machine translation system to a new domain and bidirectional translation for a new language pair (English and Italian). We focus on the interlingua design changes which were necessary to achieve high quality output in view of the language mismatches between English and Italian. The representation we propose contains features that are interpreted differently, depending on the translation direction. This decision simplified the process of creating the interlingua for individual sentences, and allows the system to defer mapping of language-specific features (such as tense and aspect), which are realized when the target syntactic feature structure is created. We also describe a set of problems we encountered in translating modal verbs, and discuss the representation of modality in our interlingua.\",\n \"Title: An Information Repository Model for Advanced Question Answering Systems.\\nYear: 2004\\n\\nAbstract: This paper presents the design and implementation of the information repository which is the central core of the JAVELIN open- domain question answering system. JAVELIN is comprised of several modules that perform a wide variety of question answering (QA) tasks, such as question analysis, document and passage retrieval, answer candidate extraction, answer selection, answer justification, and planning. The architecture is designed to support comparative component-level evaluation, so that different strategies for each module can be integrated and tested in a straightforward way. Each time a module uses a particular piece of information to produce an output, a dependency is created. To support answer justification and introspective learning, the system can use this long- term memory to trace the origin of each answer it produces for a particular question. The JAVELIN Repository implements a complete, consistent relational model for all of the information associated with a question answering scenario.\",\n \"Title: Extending the self-explanation effect to second language grammar learning\\nYear: 2010\\n\\nAbstract: Self-explanation is an instructional strategy that has shown to be beneficial for math and science learning. However, it remains an open question whether these benefits will extend to other domains like second language grammar learning. Within the domain of the English article system (teaching students when to use a, an, the, or no article at all), we compare two computer-based tutoring conditions in an in vivo classroom study. In the article choice condition, students select the correct article to complete the sentence. In the explanation choice condition, students are given a sentence with the correct article highlighted and choose the rule or feature that best explains the article use. Students (N=101) in both conditions show significant learning on both procedural (article choice) and declarative (explanation choice) tasks. Not surprisingly, we found that declarative instruction (explanation choice) led to significant learning of explanations, while procedural practice (article choice) led to significant learning of the procedures. More interestingly, we also found evidence of cross-type transfer such that declarative practice led to procedural gains and procedural practice led to better understanding of the declarative rules. In general the effects of prompted self-explanation appeared somewhat stronger than those of procedural practice.\",\n \"Title: Diversifiable Bootstrapping for Acquiring High-Coverage Paraphrase Resource.\\nYear: 2012\\n\\nAbstract: Recognizing similar or close meaning on different surface form is a common challenge in various Natural Language Processing and Information Access applications. However, we identified multiple limitations in existing resources that can be used for solving the vocabulary mismatch problem. To this end, we will propose the Diversifiable Bootstrapping algorithm that can learn paraphrase patterns with a high lexical coverage. The algorithm works in a lightly-supervised iterative fashion, where instance and pattern acquisition are interleaved, each using information provided by the other. By tweaking a parameter in the algorithm, resulting patterns can be diversifiable with a specific degree one can control.\",\n \"Title: Pronominal anaphora resolution in KANTOO English-to-Spanish machine translation system.\\nYear: 2001\\n\\nAbstract: We describe the automatic resolution of pronominal anaphora using KANT Controlled English (KCE) and the KANTOO English-to-Spanish MT system. Our algorithm is based on a robust, syntax-based approach that applies a set of restrictions and preferences to select the correct antecedent. We report a success rate of 89.6% on a training corpus with 289 anaphors, and 87.5% on held-out data containing 145 anaphors. Resolution of anaphors is important in translation, due to gender mismatches among languages; our approach translates anaphors to Spanish with 97.2% accuracy.\",\n \"Title: The KANTOO Machine Translation Environment\\nYear: 2000\\n\\nAbstract: In this paper we describe the KANTOO machine translation environment, a set of software services and tools for multilingual document Production. KANTOO includes modules for source language analysis, target language generation, source terminology management, target terminology management, and knowledge source development. The KANTOO system represents a complete re-design and re-implementation of the KANT machine translation system.\",\n \"Title: Detecting Subevent Structure for Event Coreference Resolution.\\nYear: 2014\\n\\nAbstract: In the task of event coreference resolution, recent work has shown the need to perform not only full coreference but also partial coreference of events. We show that subevents can form a particular hierarchical event structure. This paper examines a novel two-stage approach to finding and improving subevent structures. First, we introduce a multiclass logistic regression model that can detect subevent relations in addition to full coreference. Second, we propose a method to improve subevent structure based on subevent clusters detected by the model. Using a corpus in the Intelligence Community domain, we show that the method achieves over 3.2 BLANC F1 gain in detecting subevent relations against the logistic regression model.\",\n \"Title: Analogies, explanations, and practice: examining how task types affect second language grammar learning\\nYear: 2010\\n\\nAbstract: Self-explanation is an effective instructional strategy for improving problem solving in math and science domains. However, our previous studies, within the domain of second language grammar learning, show self-explanation to be no more effective than simple practice; perhaps the metalinguistic challenges involved in explaining using one's non-native language are hampering the potential benefits. An alternative strategy is tutoring using analogical comparisons, which reduces language difficulties while continuing to encourage feature focusing and deep processing. In this paper, we investigate adult English language learners learning the English article system (e.g. the difference between “a dog” and “the dog”). We present the results of a classroom-based study (N=99) that compares practice-only to two conditions that facilitate deep processing: self-explanation with practice and analogy with practice. Results show that students in all conditions benefit from the instruction. However, students in the practice-only condition complete the instruction in significantly less time leading to greater learning efficiency. Possible explanations regarding the differences between language and science learning are discussed.\",\n \"Title: Acquisition of large lexicons for practical knowledge-based MT\\nYear: 1994\\n\\nAbstract: . Although knowledge-based MT systems have the potential to achieve high translationaccuracy, each successful application system requires a large amount of hand-coded lexicalknowledge. Systems like KBMT-89 and its descendents have demonstrated how knowledge-basedtranslation can produce good results in technical domainswith tractable domain semantics. Nevertheless,the magnitude of the development task for large-scale applications with tens of thousandsof domain concepts precludes a purely...\",\n \"Title: Boiling down information retrieval test collections\\nYear: 2010\\n\\nAbstract: Constructing large-scale test collections is costly and time-consuming, and a few relevance assessment methods have been proposed for constructing \\\"minimal\\\" information retrieval test collections that may still provide reliable experimental results. In contrast to building up such test collections, we take existing test collections constructed through the traditional pooling approach and empirically investigate whether they can be \\\"boiled down.\\\" More specifically, we report on experiments with test collections from both NT-CIR and TREC to investigate the effect of reducing both the topic set size and the pool depth on the outcome of a statistical significance test between two systems, starting with (approximately) 100 topics and depth-100 pools. We define cost (of manual relevance assessment) as the pool depth multiplied by the topic set size, and error as a system pair whose outcome of statistical significance testing differs from the original result based on the full test collection. Our main findings are: (a) Cost and the number of errors are negatively correlated, and any attempt at substantially reducing cost introduces some errors; (b) The NTCIR-7 IR4QA and the TREC 2004 robust track test collections all yield a comparable and considerable number of errors in response to cost reduction, and this is true despite the fact that the TREC relevance assessments relied on more than twice as many runs as the NTCIR ones; (c) Using 100 topics with depth-30 pools generally yields fewer errors than using 30 topics with depth-100 pools; and (d) Even with depth-100 pools, using fewer than 100 topics results in false alarms, i.e. two systems are declared significantly different even though the full topic set would declare otherwise.\",\n \"Title: Coping with ambiguity in a large-scale machine translation system\\nYear: 1994\\n\\nAbstract: In an interlingual knowledge-based machine translation system, ambignuity arises when the source language analyzer produces more than one interlingua expression for a source sentence. This can have a negative impact on translation quality, since a target sentence may be produced from an unintended meaning. In this paper we describe the methods used in the KANT machine translation system to reduce or eliminate ambiguity in a large-scale application domain. We also test these methods on a large corpus of test sentences, in order to illustrate how the different disambiguation methods reduce the average number of parses per sentence.\",\n \"Title: Supervised Within-Document Event Coreference using Information Propagation.\\nYear: 2014\\n\\nAbstract: Event coreference is an important task for full text analysis. However, previous work uses a variety of approaches, sources and evaluation, making the literature confusing and the results incommensurate. We provide a description of the differences to facilitate future research. Second, we present a supervised method for event coreference resolution that uses a rich feature set and propagates information alternatively between events and their arguments, adapting appropriately for each type of argument.\",\n \"Title: Overview of the NTCIR-8 ACLIA Tasks: Advanced Cross-Lingual Information Access\\nYear: 2010\\n\\nAbstract: paper presents an overview of the ACLIA (Advanced Cross-Lingual Information Access) task cluster at NTCIR-8. The task overview includes: a definition of and motivation for the evaluation; a description of the complex and factoid question types evaluated; the document sources and exchange formats selected and/or defined; the official metrics used in evaluating participant runs; the tools and process used to develop the official evaluation topics; summary data regarding the runs submitted; and the results of evaluating the submitted runs with the official metrics.\",\n \"Title: Analyzing the Effects of Spoken Dialog Systems on Driving Behavior\\nYear: 2006\\n\\nAbstract: This paper presents an evaluation of a spoken dialog system for automotive environments. Our overall goal was to measure the impact of user-system interaction on the user's driving performance, and to determine whether adding context-awareness to the dialog system might reduce the degree of user distraction during driving. To address this issue, we incorporated context-awareness into a spoken dialog system, and implemented three system features using user context, network context and dialog context. A series of experiments were conducted under three different configurations: driving without a dialog system, driving while using a context-aware dialog system, and driving while using a context-unaware dialog system. We measured the differences between the three configurations by comparing the average car speed, the frequency of speed changes and the angle between the car's direction and the centerline on the road. These results indicate that context-awareness could reduce the degree of user distraction when using a dialog system during driving.\",\n \"Title: Multimodal knowledge-based analysis in multimedia event detection\\nYear: 2012\\n\\nAbstract: Multimedia Event Detection (MED) is a multimedia retrieval task with the goal of finding videos of a particular event in a large-scale Internet video archive, given example videos and text descriptions. We focus on the multimodal knowledge-based analysis in MED where we utilize meaningful and semantic features such as Automatic Speech Recognition (ASR) transcripts, acoustic concept indexing (i.e. 42 acoustic concepts) and visual semantic indexing (i.e. 346 visual concepts) to characterize videos in archive. We study two scenarios where we either do or do not use the provided example videos. In the former, we propose a novel Adaptive Semantic Similarity (ASS) to measure textual similarity between ASR transcripts of videos. We also incorporate acoustic concept indexing and classification to retrieve test videos, specially with too few spoken words. In the latter 'ad-hoc' scenario where we do not have any example video, we use only the event kit description to retrieve test videos ASR transcripts and visual semantics. We also propose an event-specific fusion scheme to combine textual and visual retrieval outputs. Our results show the effectiveness of the proposed ASS and acoustic concept indexing methods and their complimentary role. We also conduct a set of experiments to assess the proposed framework for the 'ad-hoc' scenario.\",\n \"Title: Easy Samples First: Self-paced Reranking for Zero-Example Multimedia Search\\nYear: 2014\\n\\nAbstract: Reranking has been a focal technique in multimedia retrieval due to its efficacy in improving initial retrieval results. Current reranking methods, however, mainly rely on the heuristic weighting. In this paper, we propose a novel reranking approach called Self-Paced Reranking (SPaR) for multimodal data. As its name suggests, SPaR utilizes samples from easy to more complex ones in a self-paced fashion. SPaR is special in that it has a concise mathematical objective to optimize and useful properties that can be theoretically verified. It on one hand offers a unified framework providing theoretical justifications for current reranking methods, and on the other hand generates a spectrum of new reranking schemes. This paper also advances the state-of-the-art self-paced learning research which potentially benefits applications in other fields. Experimental results validate the efficacy and the efficiency of the proposed method on both image and video search tasks. Notably, SPaR achieves by far the best result on the challenging TRECVID multimedia event search task.\",\n \"Title: Text-to-video: a semantic search engine for internet videos\\nYear: 2016\\n\\nAbstract: Abstract Semantic search or text-to-video search in video is a novel and challenging problem in information and multimedia retrieval. Existing solutions are mainly limited to text-to-text matching, in which the query words are matched against the user-generated metadata. This kind of text-to-text search, though simple, is of limited functionality as it provides no understanding about the video content. This paper presents a state-of-the-art system for event search without any user-generated metadata or example videos, known as text-to-video search. The system relies on substantial video content understanding and allows for searching complex events over a large collection of videos. The proposed text-to-video search can be used to augment the existing text-to-text search for video. The novelty and practicality are demonstrated by the evaluation in NIST TRECVID 2014, where the proposed system achieves the best performance. We share our observations and lessons in building such a state-of-the-art system, which may be instrumental in guiding the design of the future system for video search and analysis.\",\n \"Title: JAVELIN III: Cross-Lingual Question Answering from Japanese and Chinese Documents\\nYear: 2007\\n\\nAbstract: In this paper, we describe the JAVELIN Cross Language Question Answering system, which includes modules for question analysis, keyword translation, document retrieval, information extraction and answer generation. In the NTCIR6 CLQA2 evaluation, our system achieved 19% and 13% accuracy in the English-to-Chinese and English-to-Japanese subtasks, respectively. An overall analysis and a detailed module-by-module analysis are presented.\",\n \"Title: JAVELIN III: Answering Non-Factoid Questions in Japanese\\nYear: 2007\\n\\nAbstract: In this paper, we describe our adaptation of the JAVELIN system to Japanese question answering for the NTCIR-6 QAC track. To establish a baseline Japanese-to-Japanese non-factoid question answering system, we performed the minimum extensions to our factoid question answering system. The answer boundary recognition task was simplified by introducing a \\u001cone sentence assumption \\u001d in the answer extraction phase. In the end, the performance of our machine learning-based sub-modules was affected by a scarcity of training data; nevertheless, our system performed close to the average accuracy in the number of questions correctly answered.\",\n \"Title: Overview of the NTCIR-7 ACLIA IR4QA Task\\nYear: 2008\\n\\nAbstract: This paper presents an overview of the IR4QA (In- formation Retrieval for Question Answering) Task of the NTCIR-7 ACLIA (Advanced Cross-lingual Infor- mation Access) Task Cluster. IR4QA evaluates tra- ditional ranked retrieval of documents using well- studied metrics such as Average Precision, but the re- trieval task is embedded in the context of cross-lingual question answering. That is, document retrieval is treated as a component of the entire question answer- ing system. This paper concentrates on how rele- vance assessments for the Simpified Chinese, Tradi- tional Chinese and Japanese IR4QA test collections were obtained, and the outcome of the formal IR4QA evaluation using the three collections. For the rela- tionship between IR4QA and the entire ACLIA task cluster, we refer the reader to the overview paper of ACLIA (17). For details of the individual IR4QA sys- tems, we refer the reader to the participants' reports.\",\n \"Title: Query Expansion and Machine Translation for Robust Cross-Lingual Information Retrieval\\nYear: 2008\\n\\nAbstract: In this paper, we describe the Information Retrieval subsystem of JAVELIN IV, a question-answering system that answers complex questions from multilingual sources. Our research focus is on different strategies for query term extraction, translation, filtering, expansion and weighting, including a novel alias expansion technique using lexico-syntactic patterns learned with weakly-supervised algorithm. In the NTCIR7 IR4QA evaluation, our retrieval system achieved 59% and 59% MAP in the Chinese-to-Chinese and Japanese-to- Japanese subtasks, respectively. We provide a rationale for the retrieval system design, and present a detailed error analysis for our formal run results.\",\n \"Title: Complex Cross-lingual Question Answering as a Sequential Classification and Multi-Document Summarization Task\\nYear: 2008\\n\\nAbstract: In this paper, we describe the JAVELIN IV system, which treats complex question answering as a sequential classification and multi-document summarization task. Our research and development effort is based on various forms of linguistic annotation, and a comparison of various answer extraction and summarization algorithms. We discuss the use of different units of extraction, the effect of different syntactic features for classification, and the effect of different summarization strategies. We also analyze how the performance of machine translation and information retrieval affect the performance of question answering. In the NTCIR-7 CCLQA main track official evaluation, our system achieved 16.3% and 19.2% accuracy in the English-to- Japanese and English-to-Chinese subtasks, respectively.\",\n \"Title: Bootstrap Pattern Learning for Open-Domain CLQA*.\\nYear: 2010\\n\\nAbstract: We describe Javelin, a Cross-lingual Question Answering system which participated in the NTCIR-8 ACLIA evaluation and which is designed to work on any type of question, including factoid and complex questions. The key technical contribution of this paper is a minimally supervised bootstrapping approach to generating lexico- syntactic patterns used for answer extraction. The preliminary evaluation result (measured by nugget F3 score) shows that the proposed pattern learning approach outperformed two baselines, a supervised learning approach used in NTCIR-7 ACLIA and a simple key-term based approach, for both monolingual and crosslingual tracks. The proposed approach is general and thus it has potential applicability to a wide variety of information access applications which require deeper semantic processing. Keywordslearning, minimally-supervised learning, bootstrapping.\",\n \"Title: CMU JAVELIN System for NTCIR5 CLQA1\\nYear: 2005\\n\\nAbstract: In this paper, we describe the JAVELIN Cross Lan- guage Question Answering system, which includes modules for question analysis, keyword translation, document retrieval, information extraction and an- swer generation. In the NTCIR5 CLQA1 evaluation, our system achieved 7.5% and 10.0% accuracy in the English-to-Chinese and English-to-Japanese sub- tasks, respectively. An overall analysis and a detailed module-by-module analysis are presented.\",\n \"Title: Fast and Accurate Content-based Semantic Search in 100M Internet Videos\\nYear: 2015\\n\\nAbstract: Large-scale content-based semantic search in video is an interesting and fundamental problem in multimedia analysis and retrieval. Existing methods index a video by the raw concept detection score that is dense and inconsistent, and thus cannot scale to \\\\\\\"big data\\\\\\\" that are readily available on the Internet. This paper proposes a scalable solution. The key is a novel step called concept adjustment that represents a video by a few salient and consistent concepts that can be efficiently indexed by the modified inverted index. The proposed adjustment model relies on a concise optimization framework with interpretations. The proposed index leverages the text-based inverted index for video retrieval. Experimental results validate the efficacy and the efficiency of the proposed method. The results show that our method can scale up the semantic search while maintaining state-of-the-art search performance. Specifically, the proposed method (with reranking) achieves the best result on the challenging TRECVID Multimedia Event Detection (MED) zero-example task. It only takes 0.2 second on a single CPU core to search a collection of 100 million Internet videos.\",\n \"Title: Bridging the Ultimate Semantic Gap: A Semantic Search Engine for Internet Videos\\nYear: 2015\\n\\nAbstract: Semantic search in video is a novel and challenging problem in information and multimedia retrieval. Existing solutions are mainly limited to text matching, in which the query words are matched against the textual metadata generated by users. This paper presents a state-of-the-art system for event search without any textual metadata or example videos. The system relies on substantial video content understanding and allows for semantic search over a large collection of videos. The novelty and practicality is demonstrated by the evaluation in NIST TRECVID 2014, where the proposed system achieves the best performance. We share our observations and lessons in building such a state-of-the-art system, which may be instrumental in guiding the design of the future system for semantic search in video.\",\n \"Title: SIGIR 2017 Workshop on Open Knowledge Base and Question Answering (OKBQA2017)\\nYear: 2017\\n\\nAbstract: Over the past years, several challenges and calls for research projects have pointed out the dire need for pushing natural language interfaces. In this context, the importance of Semantic Web data as a premier knowledge source is rapidly increasing. But we are still far from having accurate natural language interfaces that allow handling complex information needs in a user-centric and highly performant manner. The development of such interfaces requires collaboration of a range of different fields, including natural language processing, information extraction, knowledge base construction and population, reasoning, and question answering. With the goal to join forces in the collaborative development of natural language QA systems, the second OKBQA workshop is organized within the 40th SIGIR conference.\",\n \"Title: Event Nugget and Event Coreference Annotation.\\nYear: 2016\\n\\nAbstract: In this paper, we describe the event nugget annotation created in support of the pilot Event Nugget Detection evaluation in 2014 and in support of the Event Nugget Detection and Coreference open evaluation in 2015, which was one of the Knowledge Base Population tracks within the NIST Text Analysis Conference. We present the data volume annotated for both training and evaluation data for the 2015 evaluation as well as changes to annotation in 2015 as compared to that of 2014. We also analyze the annotation for the 2015 evaluation as an example to show the annotation challenges and consistency, and identify the event types and subtypes that are most difficult for human annotators. Finally, we discuss annotation issues that we need to take into consideration in the future.\",\n \"Title: The ARIEL-CMU situation frame detection pipeline for LoReHLT16: a model translation approach.\\nYear: 2018\\n\\nAbstract: The LoReHLT16 evaluation challenged participants to extract Situation Frames (SFs)—structured descriptions of humanitarian need situations—from monolingual Uyghur text. The ARIEL-CMU SF detector combines two classification paradigms, a manually curated keyword-spotting system and a machine learning classifier. These were applied by translating the models on a per-feature basis, rather than translating the input text. The resulting combined model provides the accuracy of human insight with the generality of machine learning, and is relatively tractable to human analysis and error correction. Other factors contributing to success were automatic dictionary creation, the use of phonetic transcription, detailed, hand-written morphological analysis, and naturalistic glossing for error analysis by humans. The ARIEL-CMU SF pipeline produced the top-scoring LoReHLT16 situation frame detection systems for the metrics SFType, SFType+Place+Need, SFType+Place+Relief, and SFType+Place+Urgency, at each of the three checkpoints.\",\n \"Title: BioAMA: Towards an End to End BioMedical Question Answering System.\\nYear: 2018\\n\\nAbstract: In this paper, we present a novel Biomedical Question Answering system, BioAMA: \\\"Biomedical Ask Me Anything\\\" on task 5b of the annual BioASQ challenge (Balikas et al., 2015). We focus on a wide variety of question types including factoid, list based, summary and yes/no type questions that generate both exact and well-formed 'ideal' answers. For summary-type questions, we combine effective IR-based techniques for retrieval and diversification of relevant snippets for a question to create an end-to-end system which achieves a ROUGE-2 score of 0.72 and a ROUGE-SU4 score of 0.71 on ideal answer questions (7% improvement over the previous best model). Additionally, we propose a novel Natural Language Inference (NLI) based framework to answer the yes/no questions. To train the NLI model, we also devise a transfer-learning technique by cross-domain projection of word embeddings. Finally, we present a two-stage approach to address the factoid and list type questions by first generating a candidate set using NER taggers and ranking them using both supervised and unsupervised techniques.\",\n \"Title: Graph Based Decoding for Event Sequencing and Coreference Resolution.\\nYear: 2018\\n\\nAbstract: Events in text documents are interrelated in complex ways. In this paper, we study two types of relation: Event Coreference and Event Sequencing. We show that the popular tree-like decoding structure for automated Event Coreference is not suitable for Event Sequencing. To this end, we propose a graph-based decoding algorithm that is applicable to both tasks. The new decoding algorithm supports flexible feature sets for both tasks. Empirically, our event coreference system has achieved state-of-the-art performance on the TAC-KBP 2015 event coreference task and our event sequencing system beats a strong temporal-based, oracle-informed baseline. We discuss the challenges of studying these event relations.\",\n \"Title: Automatic Event Salience Identification.\\nYear: 2018\\n\\nAbstract: Identifying the salience (i.e. importance) of discourse units is an important task in language understanding. While events play important roles in text documents, little research exists on analyzing their saliency status. This paper empirically studies the Event Salience task and proposes two salience detection models based on content similarities and discourse relations. The first is a feature based salience model that incorporates similarities among discourse units. The second is a neural model that captures more complex relations between discourse units. Tested on our new large-scale event salience corpus, both methods significantly outperform the strong frequency baseline, while our neural model further improves the feature based one by a large margin. Our analyses demonstrate that our neural model captures interesting connections between salience and discourse unit relations (e.g., scripts and frame structures).\",\n \"Title: Correction grammars for error handling in a speech dialog system\\nYear: 2004\\n\\nAbstract: Speech recognition errors are inevitable in a speech dialog system. This paper presents an error handling method based on correction grammars which recognize the correction utterances which follow a recognition error. Correction grammars are dynamically created from existing grammars and a set of correction templates. We also describe a prototype dialog system which incorporates this error handling method, and provide empirical evidence that this method can improve dialog success rate and reduce the number of dialog turns required for error recovery.\",\n \"Title: The ARIEL-CMU Systems for LoReHLT18.\\nYear: 2019\\n\\nAbstract: This paper describes the ARIEL-CMU submissions to the Low Resource Human Language Technologies (LoReHLT) 2018 evaluations for the tasks Machine Translation (MT), Entity Discovery and Linking (EDL), and detection of Situation Frames in Text and Speech (SF Text and Speech).\",\n \"Title: Retrieve, Caption, Generate: Visual Grounding for Enhancing Commonsense in Text Generation Models.\\nYear: 2022\\n\\nAbstract: We investigate the use of multimodal information contained in images as an effective method for enhancing the commonsense of Transformer models for text generation. We perform experiments using BART and T5 on concept-to-text generation, specifically the task of generative commonsense reasoning, or CommonGen. We call our approach VisCTG: Visually Grounded Concept-to-Text Generation. VisCTG involves captioning images representing appropriate everyday scenarios, and using these captions to enrich and steer the generation process. Comprehensive evaluation and analysis demonstrate that VisCTG noticeably improves model performance while successfully addressing several issues of the baseline generations, including poor commonsense, fluency, and specificity.\",\n \"Title: Cross-document Event Identity via Dense Annotation.\\nYear: 2021\\n\\nAbstract: In this paper, we study the identity of textual events from different documents. While the complex nature of event identity is previously studied (Hovy et al., 2013), the case of events across documents is unclear. Prior work on cross-document event coreference has two main drawbacks. First, they restrict the annotations to a limited set of event types. Second, they insufficiently tackle the concept of event identity. Such annotation setup reduces the pool of event mentions and prevents one from considering the possibility of quasi-identity relations. We propose a dense annotation approach for cross-document event coreference, comprising a rich source of event mentions and a dense annotation effort between related document pairs. To this end, we design a new annotation workflow with careful quality control and an easy-to-use annotation interface. In addition to the links, we further collect overlapping event contexts, including time, location, and participants, to shed some light on the relation between identity decisions and context. We present an open-access dataset for cross-document event coreference, CDEC-WN, collected from English Wikinews and open-source our annotation toolkit to encourage further research on cross-document tasks.\",\n \"Title: R3: Refined Retriever-Reader Pipeline for Multidoc2dial\\nYear: 2022\\n\\nAbstract: In this paper, we present our submission to the DialDoc shared task based on the Multi-Doc2Dial dataset. MultiDoc2Dial is a conversational question answering dataset that grounds dialogues in multiple documents. The task involves grounding a user's query in a document followed by generating an appropriate response. We propose several improvements over the baseline's retriever-reader architecture to aid in modeling goal-oriented dialogues grounded in multiple documents. Our proposed approach employs sparse representations for passage retrieval, a passage re-ranker, the fusion-in-decoder architecture for generation, and a curriculum learning training paradigm. Our approach shows a 12 point improvement in BLEU score compared to the baseline RAG model.\",\n \"Title: GSRFormer: Grounded Situation Recognition Transformer with Alternate Semantic Attention Refinement\\nYear: 2022\\n\\nAbstract: ABSTRACTGrounded Situation Recognition (GSR) aims to generate structured semantic summaries of images for \\\"human-like'' event understanding. Specifically, GSR task not only detects the salient activity verb (e.g. buying), but also predicts all corresponding semantic roles (e.g. agent and goods). Inspired by object detection and image captioning tasks, existing methods typically employ a two-stage framework: 1) detect the activity verb, and then 2) predict semantic roles based on the detected verb. Obviously, this illogical framework constitutes a huge obstacle to semantic understanding. First, pre-detecting verbs solely without semantic roles inevitably fails to distinguish many similar daily activities (e.g., offering and giving, buying and selling). Second, predicting semantic roles in a closed auto-regressive manner can hardly exploit the semantic relations among the verb and roles. To this end, in this paper we propose a novel two-stage framework that focuses on utilizing such bidirectional relations within verbs and roles. In the first stage, instead of pre-detecting the verb, we postpone the detection step and assume a pseudo label, where an intermediate representation for each corresponding semantic role is learned from images. In the second stage, we exploit transformer layers to unearth the potential semantic relations within both verbs and semantic roles. With the help of a set of support images, an alternate learning scheme is designed to simultaneously optimize the results: update the verb using nouns corresponding to the image, and update nouns using verbs from support images. Extensive experimental results on challenging SWiG benchmarks show that our renovated framework outperforms other state-of-the-art methods under various metrics.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":68,"string":"68"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":66,"string":"66"}}},{"rowIdx":67,"cells":{"question_id":{"kind":"string","value":"Vinod Sharma"},"question":{"kind":"string","value":"Generate an abstract for the title \"Some algorithms for discrete time queues with finite capacity\" using the following items: queue, efficiency, moments, distribution, numerical examples."},"answer":{"kind":"string","value":"We consider a discrete time queue with finite capacity and i.i.d. and Markov modulated arrivals. Efficient algorithms are developed to calculate the moments and the distributions of the first time to overflow and the regeneration length. Results are extended to the multiserver queue. Some illustrative numerical examples are provided."},"correct_answer":{"kind":"string","value":"We consider a discrete time queue with finite capacity and i.i.d. and Markov modulated arrivals. Efficient algorithms are developed to calculate the moments and the distributions of the first time to overflow and the regeneration length. Results are extended to the multiserver queue. Some illustrative numerical examples are provided."},"documents":{"kind":"list like","value":["Title: Theoretical analysis of high-speed multiple TCP connections through multiple routers.\nYear: 2013\n\nAbstract: We study a system of multiple routers traversed by multiple TCP connections using TCP New Reno, CUBIC and Compound. More than one router may be congested. To analyze this system we will use earlier theoretical models of TCP New Reno and CUBIC but develop a new model of TCP Compound experiencing random packet losses and queuing delays. We model the router queues as M/GI/1 queues with arrival rates controlled by TCP window flow control. We also look at an alternate approach assuming proportional fairness of TCP to find the throughputs of the multiple TCP connections. These approximations are validated through comparison with ns-2 simulations.","Title: Modelling and analysis of New Coolstreaming for P2P IPTV.\nYear: 2012\n\nAbstract: Peer to peer networks are being used extensively nowadays for file sharing, video on demand and live streaming. For IPTV, delay deadlines are more stringent compared to file sharing. Coolstreaming was the first P2P IPTV system. In this paper, we model New Coolstreaming (newer version of Coolstreaming) via a queueing network. We use two time scale decomposition of Markov chains to compute the stationary distribution of number of peers and the expected number of substreams in the overlay which are not being received at the required rate due to parent overloading. We also characterize the end-to-end delay encountered by a video packet received by a user and originated at the server. Three factors contribute towards the delay. The first factor is the mean shortest path length between any two overlay peers in terms of overlay hops of the partnership graph which is shown to be O (log n) where n is the number of peers in the overlay. The second factor is the mean number of routers between any two overlay neighbours which is seen to be at most O (log N-I) where N-I is the number of routers in the internet. Third factor is the mean delay at a router in the internet. We provide an approximation of this mean delay E [W]. Thus, the mean end to end delay in New Coolstreaming is shown to be upper bounded by O [(log E [N]) (log N-I) E (W)] where E [N] is the mean number of peers at a channel.","Title: Distributed Joint Source-Channel Coding for Functions over a Multiple Access Channel\nYear: 2009\n\nAbstract: In this paper we provide sufficient conditions for lossy transmission of functions of correlated data over a multiple access channel (MAC). The conditions obtained can be shown as generalized version of Yamamoto's result [28]. We also obtain efficient joint source-channel coding schemes for transmission of discrete and continuous alphabet sources to recover the function values.","Title: A stochastic control approach for scheduling multimedia transmissions over a polled multiaccess fading channel\nYear: 2006\n\nAbstract: We develop scheduling strategies for carrying multimedia traffic over a polled multiple access wireless network with fading. We consider a slotted system with three classes of traffic (voice, streaming media and file transfers). A Markov model is used for the fading and also for modeling voice packet arrivals and streaming arrivals. The performance objectives are a loss probability for voice, mean network delay for streaming media, and time average throughput for file transfers. A central scheduler (e.g., the access point in a single cell IEEE 802.11 wireless local area network (WLAN)) is assumed to be able to keep track of all the available state information and make the scheduling decision in each slot (e.g., as would be the case for PCF mode operation of the IEEE 802.11 WLAN). The problem is modeled as a constrained Markov decision problem. By using constraint relaxations (a linear relaxation and Whittle type relaxations) an index based policy is obtained. For the file transfers the decision problem turns out to be one with partial state information. Numerical comparisons are provided with the performance obtained from some simple policies.","Title: Performance analysis of battery power management schemes in wireless mobile devices.\nYear: 2002\n\nAbstract: In this paper, we analyze the performance of battery power management schemes in wireless mobile devices using a queueing theory approach. We model the battery as a server with finite service capacity and data packets as customers to be served. With an intent to exploit the recharging capability of the battery when left idle, we allow the battery to go on intentional vacations during which the battery can recharge itself. The recharge thus built up can effectively increase the number of customers served (in other words, battery life can be extended). Such improved battery life performance would, however, come at the expense of increased packet delay performance. We quantify the battery life gain versus delay performance trade-off in this approach through analysis and simulations. By considering a continuous recharge model of the battery, we derive expressions for the number of customers served and the mean delay for an M/GI/1 queueing system without and with server vacations. We show that allowing intentional vacations during busy periods helps to increase battery life, and that this approach can be beneficial when applied on traffic of delay-tolerant applications. We also propose a packet delay constrained power saving algorithm that will exploit the recharge phenomenon when packet delay constraints are imposed.","Title: Reliable estimation via simulation\nYear: 1995\n\nAbstract: Leta ands denote the inter arrival times and service times in aGI/GI/1 queue. Let a(n), s(n) be the r.v.s. with distributions as the estimated distributions ofa ands from iid samples ofa ands of sizesn. Letw be a r.v. with the stationary distribution p of the waiting times of the queue with input(a,s). We consider the problem of estimatingE[wa], a> 0 and a via simulations when (a(n),s(n)) are used as input. Conditions for the accuracy of the asymptotic estimate, continuity of the asymptotic variance and uniformity in the rate of convergence to the estimate are obtained. We also obtain rates of convergence for sample moments, the empirical process and the quantile process for the regenerative processes. Robust estimates are also obtained when an outlier contaminated sample ofa ands is provided. In the process we obtain consistency, continuity and asymptotic normality of M-estimators for stationary sequences. Some robustness results for Markov processes are included.","Title: Cooperative Sequential Spectrum Sensing Algorithms for OFDM\nYear: 2010\n\nAbstract: This paper considers the problem of spectrum sensing in cognitive radio\nnetworks when the primary user employs Orthogonal Frequency Division\nMultiplexing (OFDM). We develop cooperative sequential detection algorithms\nbased on energy detectors and the autocorrelation property of cyclic prefix\n(CP) used in OFDM systems and compare their performances. We show that\nsequential detection provides much better performance than the traditional\nfixed sample size (snapshot) based detectors. We also study the effect of model\nuncertainties such as timing and frequency offset, IQ-imbalance and uncertainty\nin noise and transmit power on the performance of the detectors. We modify the\ndetectors to mitigate the effects of these impairments. The performance of the\nproposed algorithms are studied via simulations. It is shown that energy\ndetector performs significantly better than the CP-based detector, except in\ncase of a snapshot detector with noise power uncertainty. Also, unlike for the\nCP-based detector, most of the above mentioned impairments have no effect on\nthe energy detector.","Title: Performance Analysis of a Cooperative System with Rateless Codes and Buffered Relays\nYear: 2011\n\nAbstract: In a cooperative relay-assisted communication system that uses rateless codes, packets get transmitted from a source to a destination at a rate that depends on instantaneous channel states of the wireless links between nodes. When multiple relays are present, the relay with the highest channel gain to the source is the first to successfully decode a packet from the source and forward it to the des...","Title: Optimal energy management policies for energy harvesting sensor nodes\nYear: 2008\n\nAbstract: We study a sensor node with an energy harvesting source. The generated energy can be stored in a buffer. The sensor node periodically senses a random field and generates a packet. These packets are stored in a queue and transmitted using the energy available at that time. We obtain energy management policies that are throughput optimal, i.e., the data queue stays stable for the largest possible data rate. Next we obtain energy management policies which minimize the mean delay in the queue. We also compare performance of several easily implementable sub-optimal energy management policies. A greedy policy is identified which, in low SNR regime, is throughput optimal and also minimizes mean delay.","Title: On Optimal Distributed Joint Source-Channel Coding for Correlated Gaussian Sources over Gaussian Channels\nYear: 2009\n\nAbstract: We consider the problem of distributed joint source-channel coding of\ncorrelated Gaussian sources over a Gaussian Multiple Access Channel (GMAC).\nThere may be side information at the decoder and/or at the encoders. First we\nspecialize a general result (for transmission of correlated sources over a MAC\nwith side information) to obtain sufficient conditions for reliable\ntransmission over a Gaussian MAC. This system does not satisfy the\nsource-channel separation. We study and compare three joint source-channel\ncoding schemes available in literature. We show that each of these schemes is\noptimal under different scenarios. One of the schemes, Amplify and Forward (AF)\nwhich simplifies the design of encoders and the decoder, is optimal at low SNR\nbut not at high SNR. Another scheme is asymptotically optimal at high SNR. The\nthird coding scheme is optimal for orthogonal Gaussian channels. We also show\nthat AF is close to the optimal scheme for orthogonal channels even at high\nSNR.","Title: Efficient Energy Management Policies for Networks with Energy Harvesting Sensor Nodes\nYear: 2008\n\nAbstract: We study sensor networks with energy harvesting nodes. The generated energy at a node can be stored in a buffer. A sensor node periodically senses a random field and generates a packet. These packets are stored in a queue and transmitted using the energy available at that time at the node. For such networks we develop efficient energy management policies. First, for a single node, we obtain policies that a re throughput optimal, i.e., the data queue stays stable for the largest possible data rate. Next we obtain energy management policies which minimize the mean delay in the queue. We also compare performance of several easily implementable sub- optimal policies. A greedy policy is identified which, in low SNR regime, is throughput optimal and also minimizes mean delay. Next using the results for a single node, we develop efficient MAC policies.","Title: Joint Source-Channel Coding on a Multiple Access Channel with Side Information\nYear: 2009\n\nAbstract: We consider the problem of transmission of several distributed correlated\nsources over a multiple access channel (MAC) with side information at the\nsources and the decoder. Source-channel separation does not hold for this\nchannel. Sufficient conditions are provided for transmission of sources with a\ngiven distortion. The source and/or the channel could have continuous alphabets\n(thus Gaussian sources and Gaussian MACs are special cases). Various previous\nresults are obtained as special cases. We also provide several good joint\nsource-channel coding schemes for discrete sources and discrete/continuous\nalphabet channel.","Title: An analytical model for capacity evaluation of VoIP on HCCA and TCP file transfers over EDCA in an IEEE 802.11e WLAN\nYear: 2006\n\nAbstract: In the context of the IEEE 802.11e standard for WLANs, we provide an analytical model for obtaining the maximum number of VoIP calls that can be supported on HCCA, such that the delay QoS constraint of the accepted calls is met, when TCP downloads are coexistent on EDCA. In this scenario, we derive the TCP download throughput by using an analytical model for the case where only TCP sessions are present in the WLAN. We show that the analytical model for combined voice and TCP transfers provides accurate results in comparison with simulations (using ns-2).","Title: Stability and Analysis of TCP Connections with RED Control and Exogenous Traffic\nYear: 2004\n\nAbstract: In this paper we study the stability and performance of a system involving several TCP connections passing through a tandem of RED controlled queues each of which has an incoming exogenous stream. The exogenous stream, representing the superposition of all incoming UDP connections into a queue, has been modeled as an MMPP stream. We consider both the TCP Tahoe and the TCP Reno versions. We start with the analysis of a single TCP connection sharing a RED controlled queue with an exogenous stream. The effect of the exogenous stream (which is almost always present in large networks) is to cause the system to converge to a stationary distribution from any initial conditions. This stability result holds good for any work conserving discipline. We also obtain the performance indices of the system; specifically the goodputs and the mean sojourn times of the various connections. The complexity involved in computation of performance indices for the system is reduced by approximating the evolution of the average queue length process of the RED queue by a deterministic ODE. Then, by using a decomposition approach of two time scales, we reduce the study of the system to that of a simplified one for which the performance measures can be obtained under stationarity. Finally, we extend the above results to the case when multiple TCP connections share a RED controlled queue with an exogenous stream and to the case when a TCP connection passes through several RED controlled tandem queues each of which has an incoming exogenous stream. We also consider an example of multiple TCPs passing through a tandem of queues. A number of simulation results have been provided which support the analysis.","Title: Comparative analysis of machine learning techniques in prognosis of type II diabetes.\nYear: 2014\n\nAbstract: Artificial Intelligence (AI) is now a days gaining immense importance and is becoming a key technology in many fields ranging from banking industry, to travel industry, to communication industry, and to robotic industry. The use of AI in medical diagnosis too is becoming increasingly popular and has been widely used in the diagnosis of tumors, cancers, hepatitis, lung diseases, etc. Numerous algorithms have been designed that help in the process of decision making by analyzing the hidden patterns in previously held information. The main objective of this manuscript is to apply multiple algorithms to a problem in the domain of medical diagnosis and analyze their efficiency in predicting the results. The problem selected for the study is the diagnosis of diabetes. Authors have identified ten parameters that play an important role in diabetes and prepared a rich database of training data which served as the backbone of the prediction algorithms. Keeping in view this training data, authors implemented three algorithms [Naïve Bayes, artificial neural networks (ANN), and K-nearest neighbors (KNN)] and developed prediction models. To calculate the efficiency, the results of prediction system were compared with the actual medical diagnosis of the subjects. The results indicate that the ANN is the best predictor with the accuracy of about 96 % which was followed by Naïve Bayes networks having an accuracy of about 95 % and the KNN came to be the worst predictor having an accuracy of about 91 %.","Title: A finite buffer queue with priorities\nYear: 2002\n\nAbstract: We consider a queue with finite buffer where the buffer size limits the amount of work that can be stored in the queue. The arrival process is a Poisson or a Markov modulated Poisson process. The service times (packet lengths) are i.i.d. with a general distribution. Our queue models the systems in the Internet more realistically than the usual M/GI/1/K queue which restricts the number of packets in the buffer rather than the buffer content (the number of bits). We obtain the stability, the rates of convergence to the stationary distribution and functional limit theorems for this system. In addition, we also obtain algorithms to compute the stationary density of the workload process, the waiting times and the probability of packet loss. Next, we study the queue with two priority classes. The higher priority traffic has preemptive-resume priority. For sharing the buffer, we consider two cases. In the first case, the buffer is shared by both the classes without any priority. In the second case, the buffer is partitioned into two groups, one reserved for each class. For this system also we obtain all the results mentioned for the single class traffic.","Title: Stability and continuity of polling systems\nYear: 1994\n\nAbstract: The stability of a polling system with exhaustive service and a finite number of users, each with infinite buffers is considered. The arrival process is more general than a Poisson process and the system is not slotted. Stochastic continuity of the stationary distributions, rates of convergence and functional limit theorems for the queue length and waiting time processes have also been proved. The results extend to the gated service discipline.","Title: Scheduling Under Fading and Partial Channel Information\nYear: 2012\n\nAbstract: We consider a scheduler for the downlink of a wireless channel when only partial channel-state information is available at the scheduler. We characterize the network stability region and provide two throughput-optimal scheduling policies. We also derive a deterministic bound on the mean packet delay in the network. Finally, we provide a throughput-optimal policy for the network under QoS constraints when real-time and rate-guaranteed data traffic may be present.","Title: Providing QoS to TCP and Real Time Connections in the Internet\nYear: 2004\n\nAbstract: We consider a system where streaming and/or real time applications, using the UDP protocol pass through a bottleneck router. Several persistent and non persistent TCP connections may also be passing through that router. Using the rate control at the UDP sources and choosing the RED parameters appropriately, we obtain pre-specified delays, little delay jitter, no packet loss, 100% channel efficiency, pre-specified throughput for the TCP and UDP streams and little rate fluctuation. We verify our control scheme by extensive simulations. Results are extended to a tandem of queues.","Title: Understanding User's Emotional Engagement to the Contents on a Smartphone Display: Psychiatric Prospective\nYear: 2013\n\nAbstract: Mobile phones are a ubiquitous and preferred communication, entertainment, and information access platform. Smartphones may provide an opportunity to better assess mood and behavior and to provide intervention timely, economical, rapid and effective intervention for those with mental disorders. This is an important target because behavioral health problems are associated with many of the medical disorders most responsible for morbidity and cost. Today, psychiatrists seek for various channels of mobile technology that can reduce evaluation costs and increase accuracy and also facilitate ubiquitous longitudinal monitoring of treatment and outcome measures on patients' smartphone. Facial expression recognition is one of the active research areas in the field of psychiatry to evaluate a patient's emotional health. Smartphone technology for recognizing facial expression of emotions is still emerging and offers an open platform for the research areas such as ubiquitous intelligence and computing. In this research, we present a framework to track user's emotional engagement to videos played on a smartphone. The presented framework processes user's video recorded from the front-facing camera of a smartphone and tracks facial features to detect joyful durations induced by the played videos. We also conducted subject studies on healthy individuals to evaluate the applied approach of emotional engagement. We believe that the presented results are promising and present a valuable insight to build ubiquitous intelligent systems that can help various areas of psychiatric research.","Title: Joint Routing, Scheduling And Power Control For Multihop Wireless Networks With Multiple Antennas\nYear: 2011\n\nAbstract: We consider the problem of Joint Routing, Scheduling and Power-control (JRSP) problem for multihop wireless networks (MHWN) with multiple antennas. We extend the problem and a (sub-optimal) heuristic solution method for JRSP in MHWN with single antennas. We present an iterative scheme to calculate link capacities(achievable rates) in the interference environment of the network using SINR model. We then present the algorithm for solving the JRSP problem. This completes a feasible system model for MHWN when nodes have multiple antennas. We show that the gain we achieve by using multiple antennas in the network is linear both in optimal performance as well as heuristic algorithmic performance.","Title: Joint Source-Channel Coding over a Fading Multiple Access Channel with Partial Channel State Information\nYear: 2009\n\nAbstract: In this paper we address the problem of transmission of correlated sources over a fast fading multiple access channel (MAC) with partial channel state information available at both the encoders and the decoder. We provide sufficient conditions for transmission with given distortions. Next these conditions are specialized to a Gaussian MAC (GMAC). We provide the optimal power allocation strategy and compare the strategy with various levels of channel state information.","Title: Estimating traffic parameters in queueing systems with local information\nYear: 1998\n\nAbstract: In ATM networks a new connection is accepted if the CAC (call acceptance controller) at the entering node decides that the network has the requisite resources for the incoming traffic. For this, the CAC will need to monitor the network congestion based on the local information available to it. In this paper we propose several schemes that the CAC can use to estimate the traffic of the users on the various routes in the network by sending a ‘probing’ stream. First we consider a single node where the probing stream could be arbitrary while the total interfering traffic is a Poisson process. Knowing the mean service time of the interfering traffic and the delays experienced by the probing stream we provide algorithms to estimate the arrival rate of the interfering traffic. We model the node as a continuous time as well as a discrete time queue. Then we generalize the assumptions on the interfering traffic to make the overall traffic at the node a general stationary ergodic stream. For the Poisson interfering traffic we also consider a tandem of queues. Finally, for a product form Kelly network we provide estimates of the arrival rates of interfering traffic and the service rates of customers on the route of the probing stream of the CAC. These estimates are also used to provide the optimal ‘reshaping’ of the traffic stream of a user based on the delays experienced by the user in the network.","Title: Joint power control, scheduling and routing for multihop energy harvesting sensor networks\nYear: 2009\n\nAbstract: We study wireless multihop energy harvesting sensor net works employed for random field estimation. The sensors sense the random field and generate data that is to be sent to a fusion node for estimation. Each sensor has an energy harvesting source and can operate in two modes: Wake and Sleep. We consider the problem of obtaining jointly optimal power control, routing and scheduling policies that ensure a fair utilization of network resources. This problem has a high computational complexity. Therefore, we develop a computationally efficient suboptimal approach to obtain good solutions to this problem. We study the optimal solution and performance of the suboptimal approach through some numerical examples.","Title: Performance analysis of a slotted-ALOHA protocol on a capture channel with fading\nYear: 2000\n\nAbstract: We consider the slotted ALOHA protocol on a channel with a capture effect. There are M users each with an infinite buffer. If in a slot, i packets are transmitted, then the probability of a successful reception of a packet is q_i. This model contains the CDMA protocols as special cases. We obtain sufficient rate conditions, which are close to necessary for stability of the system, when the arrival streams are stationary ergodic. Under the same rate conditions, for general regenerative arrival streams, we obtain the rates of convergence to stationarity, finiteness of stationary moments and various functional limit theorems. Our arrival streams contain all the traffic models suggested in the recent literature, including the ones which display long range dependence. We also obtain bounds on the stationary moments of waiting times which can be tight under realistic conditions. Finally, we obtain several results on the transient performance of the system, e.g., first time to overflow and the limits of the overflow process. We also extend the above results to the case of a capture channel exhibiting Markov modulated fading. Most of our results and proofs will be shown to hold also for the slotted ALOHA protocol without capture.","Title: Queued Cooperative Wireless Networks With Rateless Codes\nYear: 2008\n\nAbstract: Cooperative communication using rateless codes, in which the source transmits an infinite number of parity bits to the destination until the receipt of an acknowledgment, has recently attracted considerable interest. It provides a natural and efficient mechanism for accumulating mutual information from multiple transmitting relays. We develop an analysis of queued cooperative relay systems that combines the communication-theoretic transmission aspects of cooperative communication using rateless codes over Rayleigh fading channels with the queuing-theoretic aspects associated with buffering messages at the relays. Relay cooperation combined with queuing reduces the message transmission times and also helps distribute the traffic load in the network, which improves throughput significantly.","Title: An Efficient Algorithm for Cooperative Spectrum Sensing in Cognitive Radio Networks\nYear: 2008\n\nAbstract: We consider the problem of Spectrum Sensing in Cogni- tive Radio Systems. We have developed a distributed algorithm that the Secondary users can run to sense the channel cooperatively. It is based on sequential detection algorithms which optimally use the past observations. We use the algorithm on secondary users with energy detectors although it can be used with matched filter and other spectrum sensing algorithms also. The algorithm provides very low detection delays and also consumes little energy. Furthermore it causes low interference to the primary users. We compare this algo- rithm to several recently proposed algorithms and show that it de- tects changes in spectrum faster than these algorithms and uses sig- nificantly less energy.","Title: Cooperative distributed sequential spectrum sensing\nYear: 2010\n\nAbstract: We consider cooperative spectrum sensing for cognitive radios. We develop an energy efficient detector with low detection delay using sequential hypothesis testing. Sequential Probability Ratio Test (SPRT) is used at both the local nodes and the fusion center. We also analyse the performance of this algorithm and compare with the simulations. Modelling uncertainties in the distribution parameters are considered. Slow fading with and without perfect channel state information at the cognitive radios is taken into account.","Title: Performance analysis of a fluid queue with random service rate in discrete time\nYear: 2007\n\nAbstract: We consider a fluid queue in discrete time with random service rate. Such a queue has been used in several recent studies on wireless networks where the packets can be arbitrarily fragmented. We provide conditions on finiteness of moments of stationary delay, its Laplace-Stieltjes transform and various approximations under heavy traffic. Results are extended to the case where the wireless link can transmit in only a few slots during a frame.","Title: Stochastic Games on a Multiple Access Channel\nYear: 2012\n\nAbstract: We consider a scenario where N users try to access a common base station. Associated with each user is its channel state and a finite queue which varies with time. Each user chooses his power and the admission control variable in a dynamic manner so as to maximize his expected throughput. The throughput of each user is a function of the actions and states of all users. The scenario considers the situation where each user knows his channel and buffer state but is unaware of the states and actions taken by the other users. We consider the scenario when each user is saturated (i.e., always has a packet to transmit) as well as the case when each user is unsaturated. We formulate the problem as a Markov game and show connections with strategic form games. We then consider various throughput functions associated with the multiple user channel and provide algorithms for finding these equilibria.","Title: Opportunistic scheduling of wireless links\nYear: 2007\n\nAbstract: We consider the problem of scheduling of a wireless channel (server) to several queues. Each queue has its own link (transmission) rate. The link rate of a queue can vary randomly from slot to slot. The queue lengths and channel states of all users are known at the beginning of each slot. We show the existence of an optimal policy that minimizes the long term (discounted) average sum of queue lengths. The optimal policy, in general needs to be computed numerically. Then we identify a greedy (one step optimal) policy, MAX-TRANS which is easy to implement and does not require the channel and traffic statistics. The cost of this policy is close to optimal and better than other well-known policies (when stable) although it is not throughput optimal for asymmetric systems. We (approximately) identify its stability region and obtain approximations for its mean queue lengths and mean delays. We also modify this policy to make it throughput optimal while retaining good performance.","Title: Power control and transmission scheduling for network utility maximization in wireless networks\nYear: 2007\n\nAbstract: We consider a joint power control and transmission scheduling problem in wireless networks with average power constraints. While the capacity region of a wireless network is convex, a characterization of this region is a hard problem. We formulate a network utility optimization problem involving time-sharing across different \"transmission modes,\" where each mode corresponds to the set of power levels used in the network. The structure of the optimal solution is a time-sharing across a small set of such modes. We use this structure to develop an efficient heuristic approach to finding a suboptimal solution through column generation iterations. This heuristic approach converges quite fast in simulations, and provides a tool for wireless network planning.","Title: Delay Optimal Control Algorithm For A Multiaccess Fading Channel With Peak Power Constraint\nYear: 2005\n\nAbstract: We consider an optimal power and rate scheduling problem for a multiaccess fading wireless channel with the objective of minimising a weighted sum of mean packet transmission delay subject to a peak power constraint. The base station acts as a controller which, depending upon the buffer lengths and the channel state of each user, allocates transmission rate and power to individual users. We assume perfect channel state information at the transmitter and the receiver. We also assume a Markov model for the fading and packet arrival processes. The policy obtained represents a form of Indexability.","Title: An analytical model for performance evaluation of multimedia applications over EDCA in an IEEE 802.11e WLAN\nYear: 2010\n\nAbstract: We extend the modeling heuristic of (Harsha et al. 2006. In IEEE IWQoS '06, pp 178 --- 187) to evaluate the performance of an IEEE 802.11e infrastructure network carrying packet telephone calls, streaming video sessions and TCP controlled file downloads, using Enhanced Distributed Channel Access (EDCA). We identify the time boundaries of activities on the channel (called channel slot boundaries) and derive a Markov Renewal Process of the contending nodes on these epochs. This is achieved by the use of attempt probabilities of the contending nodes as those obtained from the saturation fixed point analysis of (Ramaiyan et al. 2005. In Proceedings ACM Sigmetrics, '05. Journal version accepted for publication in IEEE TON). Regenerative analysis on this MRP yields the desired steady state performance measures. We then use the MRP model to develop an effective bandwidth approach for obtaining a bound on the size of the buffer required at the video queue of the AP, such that the streaming video packet loss probability is kept to less than 1%. The results obtained match well with simulations using the network simulator, ns-2. We find that, with the default IEEE 802.11e EDCA parameters for access categories AC 1, AC 2 and AC 3, the voice call capacity decreases if even one streaming video session and one TCP file download are initiated by some wireless station. Subsequently, reducing the voice calls increases the video downlink stream throughput by 0.38 Mbps and file download capacity by 0.14 Mbps, for every voice call (for the 11 Mbps PHY). We find that a buffer size of 75KB is sufficient to ensure that the video packet loss probability at the QAP is within 1%.","Title: Queueing systems with random service rate\nYear: 2000\n\nAbstract: We consider a queue with the arrival process, the service time process and the service rate process as regenerative processes. We provide conditions for its stability, rates of convergence, finiteness of moments and functional limit theorems. This queue can model a queue serving ABR and UBR traffic in an ATM switch; a multiple access channel with TDMA or CDMA protocol and fading; a queue holding best effort or controlled and guaranteed traffic in a router in the integrated service architecture (ISA) of IP-based Internet and a scheduler in the router of a differentiated service architecture. In the process we also provide results for a queue with a leaky bucket controlled bandwidth scheduler. This result is of independent interest. We extend these results to feed-forward networks of queues. We also obtain the results when the arrival rate to the queue can be feedback controlled based on the congestion information in the queue (as in ABR service in the ATM networks or in the real time applications controlled by RTCP protocol in the Internet).","Title: Approximate theoretical models for TCP connections using different high speed congestion control algorithms in a multihop network.\nYear: 2013\n\nAbstract: We consider a multihop network when the flows may be using TCP Reno, CUBIC or Compound. We study its performance using fluid approximations. We provide theoretical justification for these approximations. Our approximations are simple, yet can be used to obtain throughput and average window size for each TCP connection with good accuracy. We compare results obtained using fluid approximations with discrete Markov chain models in [1] and [2] and with ns2 simulations. The fluid approximation models can be seen to trade-off accuracy for simplicity.","Title: Asymptotics for transient and stationary probabilities for finite and infinite buffer discrete time queues\nYear: 1997\n\nAbstract: Consider a discrete time queue with i.i.d. arrivals (see the generalisation below) and a single server with a buffer length m. Let {T}_{m} be the first time an overflow occurs. We obtain asymptotic rate of growth of moments and distributions of {T}_{m} as m \\to \\infty. We also show that under general conditions, the overflow epochs converge to a compound Poisson process. Furthermore, we show that the results for the overflow epochs are qualitatively as well as quantitatively different from the excursion process of an infinite buffer queue studied in continuous time in the literature. Asymptotic results for several other characteristics of the loss process are also studied, e.g., exponential decay of the probability of no loss (for a fixed buffer length) in time [0, n], as n \\to \\infty, total number of packets lost in [0, n], maximum run of loss states in [0, n]. We also study tails of stationary distributions. All results extend to the multiserver case and most to a Markov modulated arrival process.","Title: Capacity of Gaussian Channels With Energy Harvesting and Processing Cost\nYear: 2014\n\nAbstract: Energy harvesting sensor nodes are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting green communication. In this paper, we focus on communicating reliably over an additive white Gaussian noise channel using such an energy harvesting sensor node. An important part of this paper involves appropriate modeling of energy harvesting, as done via various practical architectures. Our main result is the characterization of the Shannon capacity of the communication system. The key technical challenge involves dealing with the dynamic (and stochastic) nature of the (quadratic) cost of the input to the channel. As a corollary, we find close connections between the capacity achieving energy management policies and the queueing theoretic throughput optimal policies.","Title: Analytical Model for Congestion Control and Throughput with TCP CUBIC Connections.\nYear: 2011\n\nAbstract: We develop a Markov model for a TCP CUBIC connection. Next we use it to obtain approximate expressions for throughput when there may be queuing in the network. Finally we provide the throughputs different TCP CUBIC and TCP NewReno connections obtain while sharing a channel when they may have different round trip delays and packet loss probabilities.","Title: Error Exponent Analysis of Energy-Based Bayesian Spectrum Sensing under Fading Channels.\nYear: 2011\n\nAbstract: This paper analyzes the error exponents in Bayesian decentralized spectrum sensing, i.e., the detection of occupancy of the primary spectrum by a cognitive radio, with probability of error as the performance metric. At the individual sensors, the error exponents of a Central Limit Theorem (CLT) based detection scheme are analyzed. At the fusion center, a K-out-of-N rule is employed to arrive at the overall decision. It is shown that, in the presence of fading, for a fixed number of sensors, the error exponents with respect to the number of observations at both the individual sensors as well as at the fusion center are zero. This motivates the development of the error exponent with a certain probability as a novel metric that can be used to compare different detection schemes in the presence of fading. The metric is useful, for example, in answering the question of whether to sense for a pilot tone in a narrow band (and suffer Rayleigh fading) or to sense the entire wide-band signal (and suffer log-normal shadowing), in terms of the error exponent performance. The error exponents with a certain probability at both the individual sensors and at the fusion center are derived, with both Rayleigh as well as log-normal shadow fading. Numerical results are used to illustrate and provide a visual feel for the theoretical expressions obtained.","Title: Capacity of Gaussian MAC Powered by Energy Harvesters without Storage Buffer\nYear: 2012\n\nAbstract: We consider a Gaussian multiple access channel (GMAC) where the users are sensor nodes powered by energy harvesters. The energy harvester has no buffer to store the harvested energy and hence the energy need to be expended immediately. We assume that the decoder has perfect knowledge of the energy harvesting process. We characterize the capacity region of such a GMAC. We also provide the capacity region when one of the users has infinite buffer to store the energy harvested. Next we find the achievable rates when the energy harvesting information is not available at the decoder.","Title: Amplify and forward for correlated data gathering over hierarchical sensor networks\nYear: 2009\n\nAbstract: We address the problem of estimating a random field via a wireless sensor network. We use a Multiple Access Channel (MAC) as the basic building block for such a network. For Gaussian sources over Gaussian MACs, we show that Amplify and Forward scheme (AF) performs well in such sensor network scenarios where the battery power is at a premium. We then extend this result to the hierarchical network scenario and show that it can perform favourably to the Slepian-Wolf based source coding and independent channel coding scheme. Since AF is simple and scalable, a good performance makes it an attractive scheme.","Title: A unified approach for analyzing persistent, non-persistent and ON-OFF TCP sessions in the internet\nYear: 2006\n\nAbstract: Most of the studies on TCP assume a fixed number of persistent TCP connections. A few of the recent studies look at non-persistent TCP connections but with many limiting assumptions. We look at a bottleneck router which has real time UDP traffic, TCP ON-OFF traffic and a stochastic flow of non-persistent TCP connections going through it. Our analysis is able to handle a large number (100s) of TCP connections and still provides the mean file download times of each of these connections when all of them have different packet sizes, round trip times and max window size. Using this approach we are able to model almost all the different traffic types that exist in the Internet today. We also study systems employing RED control, which is recommeded to be used in the Internet. We demostrate the effectiveness of RED for congestion control in realistic Internet scenarios both theoretically and via simulations.","Title: Some limit theorems for regenerative queues\nYear: 1998\n\nAbstract: We consider a single server queue with the interarrival times and the service times forming a regenerative sequence. This traffic class includes the standard models: \\mathit{iid}, periodic, Markov modulated (e.g., BMAP model of Lucantoni [18]) and their superpositions. This class also includes the recently proposed traffic models in high speed networks, exhibiting long range dependence. Under minimal conditions we obtain the rates of convergence to stationary distributions, finiteness of stationary moments, various functional limit theorems and the continuity of stationary distributions and moments. We use the continuity results to obtain approximations for stationary distributions and moments of an MMPP/GI/1 queue where the modulating chain has a countable state space. We extend all our results to feed-forward networks where the external arrivals to each queue can be regenerative. In the end we show that the output process of a leaky bucket is regenerative if the input process is and hence our results extend to a queue with arrivals controlled by a leaky bucket.","Title: Achieving Shannon Capacity in a Wiretap Channel via Previous Messages.\nYear: 2014\n\nAbstract: In this paper we consider a wiretap channel with a secret key buffer. We use the coding scheme of [1] to enhance the secrecy rate to the capacity of the main channel, while storing each securely transmitted message in the secret key buffer. We use the oldest secret bits from the buffer to be used as a secret key to transmit a message in a slot and then remove those bits. With this scheme we are able to prove stronger results than those in [1]. i.e., not only the message which is being transmitted currently, but all the messages transmitted in last $N_1$ slots are secure with respect to all the information that the eavesdropper possesses, where $N_1$ can be chosen arbitrarily large.","Title: Information capacity of energy harvesting sensor nodes\nYear: 2011\n\nAbstract: Sensor nodes with energy harvesting sources are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting `green communication'. We study such a sensor node with an energy harvesting source and compare various architectures by which the harvested energy is used. We find its Shannon capacity when it is transmitting its observations over an AWGN channel and show that the capacity achieving energy management policies are related to the throughput optimal policies. We also obtain the capacity when energy conserving sleep-wake modes are supported and an achievable rate for the system with inefficiencies in energy storage.","Title: Queues with Service Rate Controlled by a Delayed Feedback\nYear: 2001\n\nAbstract: We consider a single queue with a Markov modulated Poisson arrival process. Its service rate is controlled by a scheduler. The scheduler receives the workload information from the queue after a delay. This queue models the buffer in an earth station in a satellite network where the scheduler resides in the satellite. We obtain the conditions for stability, rates of convergence to the stationary distribution and the finiteness of the stationary moments. Next we extend these results to the system where the scheduler schedules the service rate among several competing queues based on delayed information about the workloads in the different queues.","Title: Algorithms for routing and centralized scheduling to provide QoS in IEEE 802.16 mesh networks\nYear: 2005\n\nAbstract: We consider the problem of routing and centralized scheduling for IEEE 802.16 mesh networks. We first fix the routing, which reduces the network to a tree. We then present scheduling algorithms which provide per flow QoS (Quality of Service) guarantees to real and interactive data applications while utilizing the network resources efficiently. Our algorithms are also scalable: they do not require per flow processing and queueing and the computational requirements are minimal. We also discuss admission control policies which ensure that sufficient resources are available. We have verified our algorithms via extensive simulations.","Title: Optimal MSE Solution for a Decision Feedback Equalizer.\nYear: 2012\n\nAbstract: Due to the inherent feedback in a decision feedback equalizer (DFE) the minimum mean square error (MMSE) or Wiener solution is not known exactly. The main difficulty in such analysis is due to the propagation of the decision errors, which occur because of the feedback. Thus in literature, these errors are neglected while designing and/or analyzing the DFEs. Then a closed form expression is obtained for Wiener solution and we refer this as ideal DFE (IDFE). DFE has also been designed using an iterative and computationally efficient alternative called least mean square (LMS) algorithm. However, again due to the feedback involved, the analysis of an LMS-DFE is not known so far. In this paper we theoretically analyze a DFE taking into account the decision errors. We study its performance at steady state. We then study an LMS-DFE and show the proximity of LMS-DFE attractors to that of the optimal DFE Wiener filter (obtained after considering the decision errors) at high signal to noise ratios (SNR). Further, via simulations we demonstrate that, even at moderate SNRs, an LMS-DFE is close to the MSE optimal DFE. Finally, we compare the LMS DFE attractors with IDFE via simulations. We show that an LMS equalizer outperforms the IDFE. In fact, the performance improvement is very significant even at high SNRs (up to 33%), where an IDFE is believed to be closer to the optimal one. Towards the end, we briefly discuss the tracking properties of the LMS-DFE.","Title: AWGN Channel Capacity of Energy Harvesting Transmitters with a Finite Energy Buffer.\nYear: 2013\n\nAbstract: We consider an AWGN channel with a transmitter powered by an energy harvesting source. The node is equipped with a finite energy buffer. Such a system can be modelled as a channel with side information (about energy in the energy buffer) causally known at the transmitter. The receiver may or may not have the side information. We prove that Markov energy management policies are sufficient to achieve the capacity of the system and provide a single letter characterization for the capacity. The computation of the capacity is expensive. Therefore, we discuss an achievable scheme that is easy to compute. This achievable rate converges to the infinite buffer capacity as the buffer length increases.","Title: Open queueing networks in discrete time-some limit theorems\nYear: 1993\n\nAbstract: A finite number of nodes, each with a single server and infinite buffers, is considered in discrete time. The service may be FIFO and the service times are constant. The external arrivals and the routing decision variables form a general stationary sequence. Stability of the system is proved under these assumptions. Extension to multiple servers at a node and general stationary distributions holds. If the external input is i.i.d. and the routing is Markovian then stochastic ordering, continuity of stationary distributions, rates of convergence, a functional CLT and a functional LIL and various other limit theorems for the queue length process are also proved. Generalizations to multiple servers at nodes, customers with priority, multiple customer classes, general service length and Markov modulated external arrival cases are discussed.","Title: Convergence And Performance Analysis Of Godard Family Of Blind Equalization Algorithms\nYear: 2003\n\nAbstract: We obtain the convergence of the Godard family (including SATO and CM algorithms) In a unified way. Our assumptions are quite realistic: the channel input can be asymptotically stationary and ergodic, the channel impulse response is finite and can be stationary, ergodic (this models fading channels) and the equalizer length is finite. The noise is i.i.d. The channel Input can be discrete or continuous. Our approach allows us to approximate the whole trajectory of the equalizer coefficients. This provides estimates of the rate of convergence an the system performance (symbol error rate) can be evaluated under transience and steady state.","Title: A Joint Uplink/Downlink Opportunistic Scheduling Scheme for Infrastructure WLANs.\nYear: 2013\n\nAbstract: We propose a combined uplink/downlink opportunistic scheduling algorithm for infrastructure WLANs. In the presence of both uplink and downlink flows, an infrastructure WLAN suffers from the uplink/downlink unfairness problem which severely decreases the throughput of the access point (AP). We resolve the unfairness by maintaining a separate queue and a backoff timer for each associated mobile station (STA) at the AP. We also increase the system throughput by making the backoff time a function of the channel gains. This reduces the collision probability also. We theoretically analyze the performance of the system under symmetric statistics for all users and validate the analysis by extensive simulations. Simulation results show increase in system throughput by over 40% compared to the 802.11 MAC.","Title: Analytical models for capacity estimation of IEEE 802.11 WLANs using DCF for internet applications\nYear: 2009\n\nAbstract: We provide analytical models for capacity evaluation of an infrastructure IEEE 802.11 based network carrying TCP controlled file downloads or full-duplex packet telephone calls. In each case the analytical models utilize the attempt probabilities from a well known fixed-point based saturation analysis. For TCP controlled file downloads, following Bruno et al. (In Networking '04, LNCS 2042, pp.驴626---637), we model the number of wireless stations (STAs) with ACKs as a Markov renewal process embedded at packet success instants. In our work, analysis of the evolution between the embedded instants is done by using saturation analysis to provide state dependent attempt probabilities. We show that in spite of its simplicity, our model works well, by comparing various simulated quantities, such as collision probability, with values predicted from our model. Next we consider N constant bit rate VoIP calls terminating at N STAs. We model the number of STAs that have an up-link voice packet as a Markov renewal process embedded at so called channel slot boundaries. Analysis of the evolution over a channel slot is done using saturation analysis as before. We find that again the AP is the bottleneck, and the system can support (in the sense of a bound on the probability of delay exceeding a given value) a number of calls less than that at which the arrival rate into the AP exceeds the average service rate applied to the AP. Finally, we extend the analytical model for VoIP calls to determine the call capacity of an 802.11b WLAN in a situation where VoIP calls originate from two different types of coders. We consider N 1 calls originating from Type 1 codecs and N 2 calls originating from Type 2 codecs. For G711 and G729 voice coders, we show that the analytical model again provides accurate results in comparison with simulations.","Title: Spectrum sensing using distributed sequential detection via noisy reporting MAC.\nYear: 2015\n\nAbstract: This paper considers cooperative spectrum sensing algorithms for Cognitive Radios which focus on reducing the number of samples to make a reliable detection. We propose algorithms based on decentralized sequential hypothesis testing in which the Cognitive Radios sequentially collect the observations, make local decisions and send them to the fusion center for further processing to make a final decision on spectrum usage. The reporting channel between the Cognitive Radios and the fusion center is assumed more realistically as a Multiple Access Channel (MAC) with receiver noise. Furthermore the communication for reporting is limited, thereby reducing the communication cost. We start with an algorithm where the fusion center uses an SPRT-like (Sequential Probability Ratio Test) procedure and theoretically analyze its performance. Asymptotically, its performance is close to the optimal centralized test without fusion center noise. We further modify this algorithm to improve its performance at practical operating points. Later we generalize these algorithms to handle uncertainties in SNR and fading.","Title: Learning Equilibrium of a Stochastic Game on Gaussian Interference Channels with Incomplete Information.\nYear: 2015\n\nAbstract: We consider a wireless communication system in which $N$ transmitter-receiver pairs want to communicate with each other. Each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgment (ACK), else it sends a negative ACK (NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium (CE). In addition, we use a no regret algorithm to find a coarse correlated equilibrium (CCE) for our power allocation game. We also propose a fully distributed learning algorithm to find a Pareto optimal solution. In general Pareto points do not guarantee fairness among the users, therefore we also propose an algorithm to compute a Nash bargaining solution which is Pareto optimal and provides fairness among users. Finally, under the same game theoretic setup, we study these equilibria and Pareto points when each transmitter sends data at multiple rates rather than at a fixed rate. We compare the sum rate obtained at the CE, CCE, Nash bargaining solution and the Pareto point and also via some other well known recent algorithms.","Title: Algorithms for stochastic games on interference channels\nYear: 2014\n\nAbstract: We consider a wireless channel shared by multiple transmitter-receiver pairs. Their transmissions interfere with each other. Each transmitter-receiver pair aims to maximize its long-term average transmission rate subject to an average power constraint. This scenario is modeled as a stochastic game. We then formulate the problem of finding a Nash equilibrium (NE) as an affine variational inequality (VI) problem, and present an algorithm to solve the VI. We provide sufficient conditions for uniqueness of the NE and convergence of the algorithm which are much weaker than the sufficient conditions available in literature. We also provide a distributed algorithm to compute Pareto optimal solutions for the proposed game.","Title: Critter: Content-Rich Traffic Trace Repository\nYear: 2014\n\nAbstract: Access to current application and network data is vital to cybersecurity and networking research. Intrusion detection, steganography, traffic camouflaging, traffic classification and modeling all benefit from real-world data. Such data provides training, testing, and evaluation as well as furthers efforts to reach ground truth. Currently available network data--especially data with application-level information--is often outdated and is either private or customized to specific, narrow research needs. The biggest hurdle to obtaining such content-rich data is addressing the huge privacy risks associated with sharing such complex and open-ended data. In this paper we present a data sharing system called Critter-at-Home which addresses these challenges. Critter connects end-users willing to share data with researchers and strikes a balance between privacy risks for a data contributor and utility for a researcher.","Title: Spark: Personalized Parkinson Disease Interventions Through Synergy Between A Smartphone And A Smartwatch\nYear: 2014\n\nAbstract: Parkinson disease (PD) is a neurodegenerative disorder afflicting more than 1 million aging Americans, incurring $23 billion in annual medical costs in the U.S. alone. Approximately 90% Parkinson patients undergoing treatment have mobility related problems related to medication which prevent them doing their activities of daily living. Efficient management of PD requires complex medication regimens specifically titrated to individuals' needs. These personalized regimens are difficult to maintain for the patient and difficult to prescribe for a physician in the few minutes available during office visits. Diverging from current form of laboratory-ridden wearable sensor technologies, we have developed SPARK, a framework that leverages a synergistic combination of Smartphone and Smartwatch in monitoring multidimensional symptoms - such as facial tremors, dysfunctional speech, limb dyskinesia, and gait abnormalities. In addition, SPARK allows physicians to conduct effective tele-interventions on PD patients when they are in non-clinical settings (e. g., at home or work). Initial case series that use SPARK framework show promising results of monitoring multidimensional PD symptoms and provide a glimpse of its potential use in real-world, personalized PD interventions.","Title: Optimal power allocation policies for low powered wireless communication systems\nYear: 2014\n\nAbstract: We consider optimal average power allocation policies in a wireless channel in the presence of individual delay constraints on the transmitted packets. Power is consumed in transmission of data only. We consider the case when the power used in transmission is a linear function of the data transmitted. The transmission channel may experience multipath fading. We have developed a computationally efficient online algorithm, when there is same hard delay constraint for all packets. Later on, we generalize it to the case when there are multiple real time streams with different hard deadline constraints. Our algorithm uses linear programming and has very low complexity.","Title: Low complexity power and scheduling policies for wireless networks to provide quality of service\nYear: 2014\n\nAbstract: We consider optimal power allocation policies for a single server, multiuser system. The power is consumed in transmission of data only. The transmission channel may experience multipath fading. We obtain very efficient, low computational complexity algorithms which minimize power and ensure stability of the data queues. We also obtain policies when the users may have mean delay constraints. If the power required is a linear function of rate then we exploit linearity and obtain linear programs with low complexity.","Title: Novel distributed sequential nonparametric tests for spectrum sensing\nYear: 2014\n\nAbstract: We consider the problem of spectrum sensing in cognitive radio networks under model uncertainties, i.e., the distribution under null hypothesis and the alternate hypothesis is not known. We model the presence of the primary signal as a mean change problem. Two simple nonparametric sequential algorithms for testing the mean are proposed. These nonparametric algorithms are applied to a decentralized detection framework. These algorithms show better performance than some of the existing nonparametric tests in literature. The performance of these algorithms is analysed via theory and simulations.","Title: A new algorithm for distributed nonparametric sequential detection\nYear: 2013\n\nAbstract: We consider non parametric sequential hypothesis testing problem when the distribution under the null hypothesis is fully known but the alternate hypothesis corresponds to some other unknown distribution with some loose constraints. We propose a simple algorithm to address the problem. This is also generalized to the case when the distribution under the null hypothesis is not fully known. These problems are primarily motivated from wireless sensor networks and spectrum sensing in Cognitive Radios. A decentralized version utilizing spatial diversity is also proposed. Its performance is analysed and asymptotic properties are proved. The simulated and analysed performance of the algorithm are shown to be better than an earlier algorithm addressing the same problem with similar assumptions. We also modify the algorithm for optimizing performance when information about the prior probabilities of occurrence of the two hypotheses are known.","Title: QoS provisioning for multiple femtocells via game theory\nYear: 2014\n\nAbstract: We consider a system with multiple Femtocells (FCs) operating in a Macrocell. The transmissions in one Femtocell interfere with its neighboring Femtocells. Each Femtocell has multiple users, each requiring a minimum transmission rate. There is also peak transmit power constraint in each channel to control interference to the BS and the users in the Macrocell. We formulate the problem of channel allocation and power control in each Femtocell as a noncooperative Game. We develop efficient decentralized algorithms to obtain a Nash equilibrium (NE) that satisfies the Quality of Service (QoS) of each user, in an efficient way. We also obtain efficient decentralized algorithms to obtain fair NE when it may not be feasible to satisfy the QoS of all the users in FCs. Finally, we extend our algorithms to the case where there may be voice and data users in the system.","Title: Decomposition of field-induced transmembrane potential responses of single cardiac cells\nYear: 2002\n\nAbstract: In this study, we used a multi-site optical mapping system to record field-induced responses of single cells isolated from guinea pig hearts. The cells were stained with voltage sensitive dye di-8-ANEPPS and stimulated with two uniform field (S1-S2) pulses along their longitudinal axes. The first pulse (S1 = 5 ms, <10 V/cm) was applied during rest and elicited an action potential. The second pulse (S2 = 10 ms, 4-50 V/cm) was applied 15 ms after the break of the S1 pulse (during the action potential plateau). The transmembrane potential responses, Vm(F)s, were optically recorded from up to 12 sites along the cell length using a fiber optic based optical mapping system at a resolution of 17 or 25 microm. The field-induced Vm(F)s had a complex spatio-temporal pattern. We show that these responses can be decomposed into simpler components. The first component, termed the differential-mode component (Vmd(F)), is like the response of a passive cell. The second component, termed the common-mode component (Vmc(F)), is identical all along the cell and adds a constant offset to the differential mode response of various sites along the cell length, to produce the total Vm(F) responses of the cell.","Title: Algorithms for computing the capacity of Markov channels with side information\nYear: 2002\n\nAbstract: Consider a finite state, irreducible Markov channel {Sk}. At time k the channel output Y k depends only on the channel input Xk and the channel state Sk. Let Uk and Vk be the CSIT (channel state information at transmitter) and the CSIR (CSI at receiver) respectively. In this paper we provide algorithms to compute the capacity of the Markov channel under various assumptions on CSIT and CSIR where the assumption P(S k = s|U1k) = P(Sk|Uk) is not necessarily satisfied. Our algorithms are based on the extension of ideas developed for channels with feedback.","Title: Optimal power control for convolutional and turbo codes over fading channels\nYear: 2002\n\nAbstract: We consider the problem of optimal power allocation to a user transmitting on a fading channel. The our Is using some specific, convolutional or turbo code. The cost function to be minimized is the bit error rate. The user needs to satisfy an average power constraint We And that the optimal power policy is code and fading distribution dependent and can be significantly different from the commonly considered policies e.g, water filling and (truncated) channel inversion. The gain In BER can be substantial.","Title: Power constrained and delay optimal policies for scheduling transmission over a fading channel\nYear: 2003\n\nAbstract: I. ABSTRACT We consider an optimal power and rate scheduling problem for a single user transmitting to a base station on a fading wireless link with the objective of minimizing the mean delay subject to an average power constraint. The base station acts as a controller which, depending upon the transmitter buffer lengths and the signal power to interference ratio (SIR) on the uplink pilot channel, allocates transmission rate and power to the user. We provide structural results for an average cost optimal stationary policy under a long run average transmitter power constraint. We obtain a closed form expression relating the optimal policy when the SIR is the best, to the optimal policy for any other SIR value. We also obtain lower and upper bounds for the optimal policy.","Title: Comparison of training, blind and semi blind equalizers in MIMO fading systems using capacity as measure\nYear: 2005\n\nAbstract: Semiblind/blind equalizers are believed to work unsatisfactorily in fading MIMO channels compared to training based methods, due to slow convergence or high computational complexity. In this paper we revisit this issue. Defining a 'composite' channel for each equalizer, we compare the three algorithms based on the capacity of this channel. We show that in Ricean (with Line of sight, LOS) environment semiblind/blind algorithms outperform training equalizers. But in Rayleigh channels it is better to use training based methods. We also find the optimum training size in training and semiblind methods.","Title: Algorithms for routing and centralized scheduling in IEEE 802.16 mesh networks\nYear: 2006\n\nAbstract: IEEE 802.16 standards for Wireless Metropolitan Area Networks (WMANs) include a mesh mode of operation for improving the coverage and throughput of the network. In this paper, we consider the problem of routing and centralized scheduling for such networks. We first fix the routing, which reduces the network to a tree. We then present a finite horizon dynamic programming framework. Using it we obtain various scheduling algorithms depending upon the cost function. Next we consider simpler suboptimal algorithms and compare their performances. I. INTRODUCTION IEEE 802.16 standard (1), also known as WiMax has been specifically designed to provide wireless last-mile broadband access in the Metropolitan Area Network (MAN), delivering performance comparable to traditional cable, DSL or T1 offerings. In order to provide the coverage and data rates envisioned, even on uneven terrain, the use of multihop communication seems desirable. Hence WiMax supports a Mesh mode in which unlike the traditional cellular systems, the nodes can operate without having a direct connection with the base station. In a IEEE 802.16d Mesh network, a system that has a direct connection to backhaul services outside the Mesh network, is termed a Mesh Base Station (MBS). All other systems of a Mesh network are termed Mesh Subscriber Stations (MSS). The IEEE 802.16d standards do not support mobility. The standard specifies a centralized scheduling scheme for mesh networks. Under this scheme, the MSSs notify the MBS their data transfer requirements and the quality of their links to their neighbours. The MBS uses the topology information along with the requirements of each MSS to decide the routing and the scheduling. The MAC scheme used is TDMA and the resource allocation is in terms of time slots within a frame. The standard does not specify an algorithm for scheduling of the slots to different MSSs; neither does it specify any routing algorithm. Scheduling and routing will have significant impact on the performance of the system and will largely decide the end to end quality of service (QoS) to different users. and (12). But in these studies spectral reuse is employed. Thus scheduling in these studies cannot be used in our system.(More recently 802.16 standard also allows channel reuse with the option of minimum hop distance of 1, 3 or 7 for reuse. Taking it 7 will practically make it a system without channel reuse.) Also some of the assumptions made in these studies do not hold in our system. In (12) (p.310), Klimov's algorithm is provided where a single server is shared by various queues. The assumptions required here are also not satisfied in our setup. However we modify this algorithm and then compare with other algorithms we develop. In this paper, we present algorithms for centralized scheduling with the objective of maximizing the network throughput within the framework of the IEEE 802.16 mesh mode. We first fix the routing within the network. We then present a finite horizon dynamic programming framework which optimizes a cost function over a fixed number of time slots. Depending upon the cost function, we obtain good scheduling algorithms which are then compared with each other and also with some of the standard algorithms available in literature. As mentioned above, in this paper we provide routing and scheduling algorithms that optimize the system performance. This has also been the goal of the other studies mentioned above. However one can also look from the user's point of view to obtain algorithms which help provide end-to- end QoS (Quality of Service) to individual connections. We have used the lessons learnt in this study and modified these algorithms to provide QoS to individual real and nonreal time (which use TCP) applications in (11). The organization of the paper is as follows. Section II describes the system model. Section III provides a good rout- ing scheme. Section IV develops the scheduling algorithms and compares them via simulations. Section V concludes the paper.","Title: Efficient and fair scheduling of uplink and downlink in IEEE 802.16 OFDMA networks\nYear: 2006\n\nAbstract: We develop new scheduling algorithms for the IEEE 802.16d OFDMA/TDD based broadband wireless access system, in which radio resources of both time and frequency slots are dynamically shared by all users. Our objective is to provide a fair and efficient allocation to all the users to satisfy their quality of service. Keywords : OFDMA, fair scheduling, IEEE 802.16d, resource allocation, QoS.","Title: Distributed coding for multiple access communication with side information\nYear: 2006\n\nAbstract: In a typical sensor network scenario a goal is to monitor a spatio-temporal process through a number of inexpensive sensing nodes, the key parameter being the fidelity at which the process has to be estimated at distant locations. We study such a scenario in which multiple encoders transmit their correlated data at finite rates to a distant, common decoder over a discrete time multiple access channel under various side information assumptions. In particular, we derive an achievable rate region for this communication problem","Title: Providing QoS to Real and Data Applications in WiMAX Mesh Networks\nYear: 2008\n\nAbstract: We consider the problem of centralized routing and scheduling for IEEE 802.16 mesh networks so as to provide Quality of Service (QoS) to individual real and interactive data applications. We first obtain an optimal and fair routing and scheduling policy for aggregate demands for different source- destination pairs. We then present scheduling algorithms which provide per flow QoS guarantees while utilizing the network resources efficiently. Our algorithms are also scalable: th ey do not require per flow processing and queueing and the computation al requirements are modest. We have verified our algorithms via extensive simulations.","Title: Computing TCP Throughput in a UMTS Network\nYear: 2008\n\nAbstract: We compute the throughput obtained by a TCP connection in a UMTS environment. For downloading data at a mobile terminal, the packets of each TCP connection are stored in separate queues at the base station (node B). Also due to fragmentation of the TCP packets into Protocol Data Units (PDU) and link layer retransmissions of PDUs there can be significant delays at the queue of the node B. In such a scenario the existing models of TCP may not be sufficient. Thus, we provide a new approximate TCP model and also obtain new closed-form expressions of mean window size. Using these we obtain the throughput of a TCP connection which matches with simulations quite well. Keywords: UMTS, TCP, throughput computation, mean window size.","Title: Energy efficient change detection over a MAC using physical layer fusion\nYear: 2008\n\nAbstract: We propose a simple and energy efficient distributed change detection scheme for sensor networks based on Page's parametric CUSUM algorithm. The sensor observations are IID over time and across the sensors conditioned on the change variable. Each sensor runs CUSUM and transmits only when the CUSUM is above some threshold. The transmissions from the sensors are fused at the physical layer. The channel is modeled as a multiple access channel (MAC) corrupted with IID noise. The fusion center which is the global decision maker, performs another CUSUM to detect the change. We provide the analysis and simulation results for our scheme and compare the performance with an existing scheme which ensures energy efficiency via optimal power selection.","Title: Optimal Sleep-Wake Policies for an Energy Harvesting Sensor Node\nYear: 2009\n\nAbstract: We study a sensor node with an energy harvesting source. In any slot, the sensor node is in one of two modes: Wake or Sleep. The generated energy is stored in a buffer. The sensor node senses a random field and generates a packet when it is awake. These packets are stored in a queue and transmitted in the wake mode using the energy available in the energy buffer. We obtain energy management policies which minimize a linear combination of the mean queue length and the mean data loss rate. Then, we obtain two easily implementable suboptimal policies and compare their performance to that of the optimal policy. Next, we extend the Throughput Optimal policy developed in our previous work to sensors with two modes. Via this policy, we can increase the throughput substantially and stabilize the data queue by allowing the node to sleep in some slots and to drop some generated packets. This policy requires minimal statistical knowledge of the system. We also modify this policy to decrease the switching costs.","Title: Diversity order vs rate in an AWGN channel\nYear: 2011\n\nAbstract: We study the diversity order vs rate of an additive white Gaussian noise (AWGN) channel in the whole capacity region. We show that for discrete input as well as for continuous input, Gallager's upper bounds on error probability have exponential diversity in low and high rate region but only subexponential in the mid-rate region. For the best available lower bounds and for the practical codes one observes exponential diversity throughout the capacity region. However we also show that performance of practical codes is close to Gallager's upper bounds and the mid-rate subexponential diversity has a bearing on the performance of the practical codes. Finally we show that the upper bounds with Gaussian input provide good approximation throughout the capacity region even for finite constellation.","Title: Queuing theoretic and information theoretic capacity of energy harvesting sensor nodes\nYear: 2011\n\nAbstract: Energy harvesting sensor networks provide near perpetual operation and reduce carbon emissions thereby supporting `green communication'. We study such a sensor node powered with an energy harvesting source. We obtain energy management policies that are throughput optimal. We also obtain delay-optimal policies. Next we obtain the Shannon capacity of such a system. Further we combine the information theoretic and queuing theoretic approaches to obtain the Shannon capacity of an energy harvesting sensor node with a data queue. Then we generalize these results to models with fading and energy consumption in activities other than transmission.","Title: Joint routing, scheduling and power control in multihop MIMO networks with MAC and broadcast links\nYear: 2012\n\nAbstract: We consider the problem of joint routing, scheduling and power control in a multihop wireless network when the nodes have multiple antennas. We focus on exploiting the multiple degrees-of-freedom available at each transmitter and receiver due to multiple antennas. Specifically we use multiple antennas at each node to form multiple access and broadcast links in the network rather than just point to point links. We show that such a generic transmission model improves the system performance significantly. Since the complexity of the resulting optimization problem is very high, we also develop efficient suboptimal solutions for joint routing, scheduling and power control in this setup.","Title: Achievable secrecy sum-rate in a fading MAC-WT with power control and without CSI of eavesdropper\nYear: 2011\n\nAbstract: We consider a two user fading Multiple Access Channel with a wire-tapper (MAC-WT) where the transmitter has the channel state information (CSI) to the intended receiver but not to the eavesdropper (eve). We provide an achievable secrecy sum-rate with optimal power control. We next provide a secrecy sum-rate with optimal power control and cooperative jamming (CJ). We then study an achievable secrecy sum rate by employing an ON/OFF power control scheme which is more easily computable. We also employ CJ over this power control scheme. Results show that CJ boosts the secrecy sum-rate significantly even if we do not know the CSI of the eve's channel. At high SNR, the secrecy sum-rate (with CJ) without CSI of the eve exceeds the secrecy sum-rate (without CJ) with full CSI of the eve.","Title: Cooperative robust sequential detection algorithms for Spectrum Sensing in Cognitive Radio\nYear: 2009\n\nAbstract: We consider the problem of Spectrum Sensing in Cogni- tive Radio Networks. In our previous work we have developed Du- alCUSUM, a distributed algorithm for change detection and used it for cooperative spectrum sensing. The algorithm is based on se- quential change detection techniques which optimally use the past observations. But DualCUSUM requires the knowledge of the channel gains for each of the secondary users. In this work we mod- ify DualCUSUM to develop GLR-CUSUM which can work with imprecise estimates of the channel gains. Next we extend the algo- rithm to the case where the receiver noise power is also not known exactly. We show that the SNR wall problem encountered in this scenario is not experienced by our algorithm. We also analyze these algorithms theoretically.","Title: Diversity-rate trade-off for fading channels with power control\nYear: 2012\n\nAbstract: We consider a complex, additive, white Gaussian noise channel with flat fading. We study its diversity order vs transmission rate for some known power allocation schemes. The capacity region is divided into three regions. For one power allocation scheme, the diversity order is exponential throughout the capacity region. For selective channel inversion (SCI) scheme, the diversity order is exponential in low and high rate region but polynomial in mid rate region. For fast fading case we also provide a new upper bound on block error probability and a power allocation scheme that minimizes it. The diversity order behaviour of this scheme is same as for SCI but provides lower BER than the other policies.","Title: Cyclic Prefix Based Cooperative Sequential Spectrum Sensing Algorithms for OFDM\nYear: 2010\n\nAbstract: This paper considers the problem of spectrum sensing in cognitive radio networks when the primary user is using Orthogonal Frequency Division Multiplexing (OFDM). For this we develop cooperative sequential detection algorithms that use the autocorrelation property of cyclic prefix (CP) used in OFDM systems. We study the effect of timing and frequency offset, IQ-imbalance and uncertainty in noise and transmit power. We also modify the detector to mitigate the effects of these impairments. The performance of the proposed algorithms is studied via simulations. We show that sequential detection can significantly improve the performance over a fixed sample size detector.","Title: Previous messages provide the key to achieve shannon capacity in a wiretap channel\nYear: 2013\n\nAbstract: We consider a wiretap channel and use previously transmitted messages to generate a secret key which increases the secrecy capacity. This can be bootstrapped to increase the secrecy capacity to the Shannon capacity without using any feedback or extra channel while retaining the strong secrecy of the wiretap channel.","Title: New algorithms for wideband spectrum sensing via compressive sensing\nYear: 2013\n\nAbstract: We consider the problem of spectrum sensing in a Cognitive Radio (CR) system when the primaries can be occupying a few subbands in a wideband spectrum. Since the primary signal dimension is large, Nyquist rate can be very high. Compressive sensing (CS) can be useful in this setup. However a CR system needs to operate at a very low SNR(~ -20dB) where the compressive sensing techniques are usually not successful. Combining them with statistical techniques can be useful. But this has been difficult because the statistics of the parameters obtained from the recovery algorithms (e.g., OMP) are not available. We develop a suboptimal recovery algorithm COR for which the statistics can be easily approximated. This allows us to use Neyman Pearson technique as well as sequential detection techniques with CS. The resulting algorithms provide satisfactory performance at -20 dB SNR. In fact COR's recovery performance is better than OMP itself at low SNR. We also modify the algorithm for the scenario when the channel gains and the noise variance may also not be available.","Title: Achieving shannon capacity region as secrecy rate region in a multiple access wiretap channel\nYear: 2015\n\nAbstract: We consider a two user multiple-access channel with an eavesdropper at the receiving end. We use previously transmitted messages as a key in the next slot till we achieve the capacity region of the usual multiple access channel (MAC).","Title: A Theoretical Framework for Hierarchical Routing Games\nYear: 2010\n\nAbstract: Most theoretical research on routing games in telecommunication networks has so far dealt with reciprocal congestion effects between routed entities. Yet in networks that support differentiation between flows, the congestion experienced by a packet depends on its priority level. Another differentiation is made by compressing the packets in the low priority flow while leaving the high priority flow intact. In this paper we study such kind of routing scenarios for the case of non-atomic users and we establish conditions for the existence and uniqueness of equilibrium.","Title: Spectrum sensing via universal source coding\nYear: 2012\n\nAbstract: We consider nonparametric sequential hypothesis testing when the distribution under null hypothesis is fully known and the alternate hypothesis corresponds to some other unknown distribution. We use easily implementable universal lossless source codes to propose simple algorithms for such a setup. These algorithms are motivated from spectrum sensing application in Cognitive Radios. Universal sequential hypothesis testing using Lempel Ziv codes and Krichevsky-Trofimov estimator with Arithmetic Encoder are considered and compared for different distributions. Cooperative spectrum sensing with multiple Cognitive Radios using universal codes is also considered.","Title: Nonparametric distributed sequential detection via universal source coding\nYear: 2013\n\nAbstract: We consider nonparametric or universal sequential hypothesis testing when the distribution under the null hypothesis is fully known but the alternate hypothesis corresponds to some other unknown distribution. These algorithms are primarily motivated from spectrum sensing in Cognitive Radios and intruder detection in wireless sensor networks. We use easily implementable universal lossless source codes to propose simple algorithms for such a setup. The algorithms are first proposed for discrete alphabet. Their performance and asymptotic properties are studied theoretically. Later these are extended to continuous alphabets. Their performance with two well known universal source codes, Lempel-Ziv code and KT-estimator with Arithmetic Encoder are compared. These algorithms are also compared with the tests using various other nonparametric estimators. Finally a decentralized version utilizing spatial diversity is also proposed and analysed.","Title: Atomic hierarchical routing games in communication networks\nYear: 2010\n\nAbstract: Theoretical studies on routing games in networks have so far dealt with reciprocal congestion effects between routing entities. But, with the advent of technologies like Cognitive Radio, we have networks which support differentiation of flows. In a two priority level model a user can be high priority or low priority and there is a cost for such a classification. The point of departure of this model from the traditional routing scenarios is the absence of reciprocity in the congestion effects: The low priority flow faces congestion from both high priority as well as low priority flow while the high priority flow is immune to the congestion effects from the low priority flow. This hierarchy is naturally present in contexts where there are primary (licensed) users and secondary (unlicensed) users who can sense their environment because there are equipped with a cognitive radio. We study such kind of routing scenarios for the cases of atomic users. We establish the existence and the uniqueness of Nash equilibrium and further we show the existence of a potential function for linear congestion costs and a certain priority classification pricing scheme. Natural applications of this model to Cognitive Radio are also pointed out.","Title: Energy efficient low complexity joint scheduling and routing for wireless networks\nYear: 2015\n\nAbstract: We consider a multihop wireless network with multiple users. The channels may experience fading. The power is consumed only during transmission and is a general monotonically increasing function of rate. We provide low complexity algorithms for joint routing, scheduling and power control which ensure stability of the queues, certain minimum rates and/or upper bound on the end-to-end, mean delays.","Title: Distributed learning of equilibria for a stochastic game on interference channels\nYear: 2015\n\nAbstract: We consider a wireless communication system in which N transmitter-receiver pairs want to communicate with each other. Each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgement (ACK), else it sends a negative ACK (NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium (CE). We also propose a fully distributed learning algorithm to find a Pareto optimal solution, and we compare the utilities of each user at the CE and the Pareto point and also with some other well known recent algorithms.","Title: Stability and performance analysis of rate-based feedback flow controlled ATM networks\nYear: 1998\n\nAbstract: Motivated by ABR class of service in ATM networks, we study a continuous time queueing system with a feedback control of the arrival rate of some of the sources. The feedback about the queue length or the total workload is provided at regular intervals (variations on it, especially the traffic management specification TM 4.0, are also considered). The propagation delays can be nonnegligible. For a general class of feedback algorithms, we obtain the stability of the system in the presence of one or more bottleneck nodes in the virtual circuit. Our system is general enough that it can be useful to study feedback control in other network protocols. We also obtain rates of convergence to the stationary distributions and finiteness of moments. For the single botterneck case, we provide algorithms to compute the stationary distributions and the moments of the sojourn times in different sets of states. We also show analytically (by showing continuity of stationary distributions and moments) that for small propagation delays, we can provide feedback algorithms which have higher mean throughput, lower probability of overflow and lower delay jitter than any open loop policy. Finally these results are supplemented by some computational results.","Title: Analysis of Multiple Flows using Different High Speed TCP protocols on a General Network.\nYear: 2016\n\nAbstract: We develop analytical tools for performance analysis of multiple TCP flows (which could be using TCP CUBIC, TCP Compound, TCP New Reno) passing through a multi-hop network. We first compute average window size for a single TCP connection (using CUBIC or Compound TCP) under random losses. We then consider two techniques to compute steady state throughput for different TCP flows in a multi-hop network. In the first technique, we approximate the queues as M/G/1 queues. In the second technique, we use an optimization program whose solution approximates the steady state throughput of the different flows. Our results match well with ns2 simulations.","Title: Achieving Shannon Capacity in a Fading Wiretap Channel.\nYear: 2015\n\nAbstract: Reliable communication imposes an upper limit on the achievable rate, namely the Shannon capacity. Wyneru0027s wiretap coding, which ensures a security constraint also in addition to reliability, results in decrease of the achievable rate. To mitigate the loss in the secrecy rate, we propose a coding scheme paper where we use sufficiently old messages as key and for this scheme prove that multiple messages are secure with respect to (w.r.t.) all the information possessed by the eavesdropper. We also show that we can achieve security in the strong sense. Next we consider a fading wiretap channel with full channel state information of the eavesdropperu0027s channel and use our coding/decoding scheme to achieve secrecy capacity close to the Shannon capacity of the main channel (in the ergodic sense). Finally we also consider the case where the transmitter does not have the instantaneous information of the channel state of the eavesdropper, but only its distribution.","Title: Distributed Algorithms for Complete and Partial Information Games on Interference Channels.\nYear: 2016\n\nAbstract: We consider a Gaussian interference channel with independent direct and cross link channel gains, each of which is independent and identically distributed across time. Each transmitter-receiver user pair aims to maximize its long-term average transmission rate subject to an average power constraint. We formulate a stochastic game for this system in three different scenarios. First, we assume that each user knows all direct and cross link channel gains. Later, we assume that each user knows channel gains of only the links that are incident on its receiver. Lastly, we assume that each user knows only its own direct link channel gain. In all cases, we formulate the problem of finding a Nash equilibrium (NE) as a variational inequality (VI) problem. We present a novel heuristic for solving a VI. We use this heuristic to solve for a NE of power allocation games with partial information. We also present a lower bound on the utility for each user at any NE in the case of the games with partial information. We obtain this lower bound using a water-filling like power allocation that requires only knowledge of the distribution of a useru0027s own channel gains and average power constraints of all the users. We also provide a distributed algorithm to compute Pareto optimal solutions for the proposed games. Finally, we use Bayesian learning to obtain an algorithm that converges to an $epsilon$-Nash equilibrium for the incomplete information game with direct link channel gain knowledge only without requiring the knowledge of the power policies of the other users.","Title: Error exponent analysis of energy-based Bayesian decentralized spectrum sensing under fading\nYear: 2015\n\nAbstract: This paper considers decentralized spectrum sensing, i.e., detection of occupancy of the primary users' spectrum by a set of Cognitive Radio (CR) nodes, under a Bayesian set-up. The nodes use energy detection to make their individual decisions, which are combined at a Fusion Center (FC) using the K -out-of- N fusion rule. The channel from the primary transmitter to the CR nodes is assumed to undergo fading, while that from the nodes to the FC is assumed to be error-free. In this scenario, a novel concept termed as the Error Exponent with a Confidence Level (EECL) is introduced to evaluate and compare the performance of different detection schemes. Expressions for the EECL under general fading conditions are derived. As a special case, it is shown that the conventional error exponent both at individual sensors, and at the FC is zero. Further, closed-form lower bounds on the EECL are derived under Rayleigh fading and lognormal shadowing. As an example application, it answers the question of whether to use pilot-signal based narrowband sensing, where the signal undergoes Rayleigh fading, or to sense over the entire bandwidth of a wideband signal, where the signal undergoes lognormal shadowing. Theoretical results are validated using Monte Carlo simulations.","Title: Information rates over an AWGN channel with an energy harvesting transmitter having a finite energy buffer\nYear: 2015\n\nAbstract: We consider an AWGN channel with a transmitter powered by an energy harvesting source. The node is equipped with a finite energy buffer. Such a system can be modelled as a channel with side information (about energy in the energy buffer) causally known at the transmitter. The receiver is assumed to have no side information. First, we provide an achievable scheme that approximates the system capacity at low buffer lengths. Next we consider a scheme viz. the truncated Gaussian signalling that provides excellent approximation to system capacity at large buffer lengths. These achievable rates are easy to compute and converge to the infinite buffer capacity as the buffer length increases. The achievable schemes we discuss belong to a general class of policies called Markov energy management policies. Markov energy management policies together with Shannon strategies provide good lower bounds to the system capacity.","Title: Power allocation games on interference channels with complete and partial information\nYear: 2015\n\nAbstract: We consider a Gaussian interference channel with independent direct and cross link channel gains, each of which is independent and identically distributed across time. Each transmitter-receiver user pair aims to maximize its long-term average transmission rate subject to an average power constraint. We formulate a stochastic game for this system in three different scenarios. First, we assume that each user knows all direct and cross link channel gains. Later, we assume that each user knows channel gains of only the links that are incident on its receiver. Lastly, we assume that each user knows only its own direct link channel gain. In all cases, we formulate the problem of finding the Nash equilibrium as a variational inequality (VI) problem and present a novel heuristic for solving the VI. We also present a lower bound on the utility for each user at any Nash equilibrium in the case of the games with partial information. We obtain this lower bound using a water-filling like power allocation that requires only knowledge of the distribution of a user's own channel gains and average power constraints of all users.","Title: Throughput of TCP over Cognitive Radio Channels.\nYear: 2016\n\nAbstract: We study TCP performance over ON-OFF channels, i.e., channels which are busy/unavailable for transmissions intermittently. The data may also be subject to random errors. Such situations arise in cognitive radio networks when secondary users opportunistically use the channel when the licensed user is not using it. We use a Markov model to evaluate the TCP throughput and probability of retransmission timeout when the ON-OFF periods are exponentially distributed and then extend it to phase-type ON and phase-type OFF periods. We then generalize the Markovian model to more general ON-OFF duration distributions and also to multiple TCP connections.","Title: Performance Based Evaluation of Various Machine Learning Classification Techniques for Chronic Kidney Disease Diagnosis.\nYear: 2016\n\nAbstract: Areas where Artificial Intelligence (AI) u0026 related fields are finding their applications are increasing day by day, moving from core areas of computer science they are finding their applications in various other domains.In recent times Machine Learning i.e. a sub-domain of AI has been widely used in order to assist medical experts and doctors in the prediction, diagnosis and prognosis of various diseases and other medical disorders. In this manuscript the authors applied various machine learning algorithms to a problem in the domain of medical diagnosis and analyzed their efficiency in predicting the results. The problem selected for the study is the diagnosis of the Chronic Kidney Disease.The dataset used for the study consists of 400 instances and 24 attributes. The authors evaluated 12 classification techniques by applying them to the Chronic Kidney Disease data. In order to calculate efficiency, results of the prediction by candidate methods were compared with the actual medical results of the subject.The various metrics used for performance evaluation are predictive accuracy, precision, sensitivity and specificity. The results indicate that decision-tree performed best with nearly the accuracy of 98.6%, sensitivity of 0.9720, precision of 1 and specificity of 1.","Title: Resource Allocation in a MAC with and without security via Game Theoretic Learning.\nYear: 2017\n\nAbstract: In this paper, we study a K-user fading multiple access channel (F-MAC), with and without an eavesdropper (Eve). In the system without Eve, we assume that each user knows only its own channel gain and is completely ignorant about the other users’ channel state. The legitimate receiver sends a short acknowledgement message Acknowledge (ACK) if the message is correctly decoded and a No Acknowledge (NACK) if the message is not correctly decoded. Under these assumptions, we use game theoretic learning setup to make transmitters learn about the power allocation under each state. We use multiplicative weight no-regret algorithm to achieve an ε-coarse correlated equilibrium. We also consider the case where a user can receive other users’ ACK/NACK messages. Now, we can maximize a weighted sum utility and achieve Pareto optimal points. We also obtain Nash bargaining solutions, which are Pareto points that are fairer to the transmitting users. Fairness among users is quantified using Jain’s index.","Title: On Strategic Multi-Antenna Jamming in Centralized Detection Networks.\nYear: 2017\n\nAbstract: In this letter, we model a complete-information zero-sum game between a centralized detection network with a multiple access channel between the sensors and the fusion center (FC), and a jammer with multiple transmitting antennas. We choose error probability at the FC as the performance metric, and investigate pure strategy equilibria for this game, and show that the jammer has no impact on the FC...","Title: A Distributed Algorithm for Quality-of-Service Provisioning in Multihop Networks.\nYear: 2017\n\nAbstract: We present a distributed algorithm for joint power control, routing and scheduling in multihop wireless networks. The algorithm also provides for Quality of Service (QoS) guarantees, namely, end-to-end mean delay guarantees and hard deadline guarantees, for different users. It is easily implementable and works by giving local dynamic priority to flows requiring QoS, the priority being a function of the queue length at the nodes. We provide theoretical bounds for the stability properties of the algorithm. We also compare the performance of the algorithm with other existing algorithms by means of extensive simulations, and demonstrate its efficacy in providing QoS on demand.","Title: Jointly broadcasting data and power with quality of service guarantees\nYear: 2017\n\nAbstract: In this work, we consider a scenario wherein an energy harvesting wireless radio equipment sends information to multiple receivers alongside powering them. In addition to harvesting the incoming radio frequency (RF) energy, the receivers also harvest energy from its environment (e.g., solar energy). This communication framework is captured by a fading Gaussian Broadcast Channel (GBC) with energy harvesting transmitter and receivers. In order to ensure some quality of service (QoS) in data reception among the receivers, we impose a minimumrate requirement on data transmission. For the setting in place, we characterize the fundamental limits in jointly transmitting information and power subject to a QoS guarantee, for three cardinal receiver structures namely, ideal, time-switching and power-splitting. We show that a time-switching receiver can switch between information reception mode and energy harvesting mode, without the transmitter's knowledge of the same and without any extra rate loss. We also prove that, for the same amount of power transferred, on average, a power-splitting receiver supports higher data rates compared to a time-switching receiver.","Title: Information and Power Transfer by Energy Harvesting Transmitters over a Fading Multiple Access Channel with Minimum Rate Constraints.\nYear: 2016\n\nAbstract: We consider the problem of Simultaneous Wireless Information and Power Transfer (SWIPT) over a fading multiple access channel with additive Gaussian noise. The transmitters as well as the receiver harvest energy from ambient sources. We assume that the transmitters have two classes of data to send, viz. delay sensitive and delay tolerant data. Each transmitter sends the delay sensitive data at a certain minimum rate irrespective of the channel conditions (fading states). In addition, if the channel conditions are good, the delay tolerant data is sent. {Along with data, the transmitters also transfer power to aid the receiver in meeting its energy requirements.} In this setting, we characterize the textit{minimum-rate capacity region} which provides the fundamental limit of transferring information and power simultaneously with minimum rate guarantees. Owing to the limitations of current technology, these limits might not be achievable in practice. Among the practical receiver structures proposed for SWIPT in literature, two popular architectures are the textit{time switching} and textit{power splitting} receivers. For each of these architectures, we derive the minimum-rate capacity regions. We show that power splitting receivers although more complex, provide a larger capacity region.","Title: Finite Blocklength Analysis Of Energy Harvesting Channels\nYear: 2016\n\nAbstract: We consider additive white Gaussian noise channels and discrete memoryless channels where the transmitter harvests energy from the environment. These can model wireless sensor networks as well as Internet of Things. By providing a unifying framework that works for any energy harvesting channel, we study these channels assuming an infinite energy buffer and provide the corresponding achievability and converse bounds on the channel capacity in the finite blocklength regime. We additionally provide moderate deviation asymptotic bounds.","Title: An asymptotic approximation for TCP compound.\nYear: 2017\n\nAbstract: In this paper, we derive an approximation for throughput of TCP Compound connections under random losses. Throughput expressions for TCP Compound under a deterministic loss model exist in the literature. These are obtained assuming that the window sizes are continuous, i.e., a fluid behavior is assumed. We validate this model theoretically. We show that under the deterministic loss model, the TCP window evolution for TCP Compound is asymptotically periodic and is independent of the initial window size. We then consider the case when packets are lost randomly and independently of each other. We discuss Markov chain models to analyze performance of TCP in this scenario. We use insights from the deterministic loss model to get an appropriate scaling for the window size process and show that these scaled processes, indexed by p, the packet error rate, converge to a limit Markov chain process as p goes to 0. We show the existence and uniqueness of the stationary distribution for this limit process. Using the stationary distribution for the limit process, we obtain approximations for throughput, under random losses, for TCP Compound when packet error rates are small. We compare our results with ns2 simulations which show a good match and a better approximation than the fluid model at low p.","Title: An Achievable Rate for an Optical Channel with Finite Memory.\nYear: 2017\n\nAbstract: A fiber optic channel is modeled in a variety of ways; from the simple additive white complex Gaussian noise model, to models that incorporate memory in the channel. Because of Kerr nonlinearity, a simple model is not a good approximation to an optical fiber. Hence we study a fiber optic channel with finite memory and provide an achievable bound on channel capacity that improves upon a previously known bound.","Title: Finite Blocklength Rates over a Fading Channel with CSIT and CSIR\nYear: 2018\n\nAbstract: In this work, we obtain lower and upper bounds on the maximal {transmission} rate at a given codeword length $n$, average probability of error $\\epsilon$ and power constraint $\\bar{P}$, over a finite valued, block fading additive white Gaussian noise (AWGN) channel with channel state information (CSI) at the transmitter {and the receiver}. {These bounds characterize} deviation of the finite blocklength coding rates from the channel capacity which is in turn achieved by the \\textit{water filling} power allocation across time. {The bounds obtained also} characterize the rate enhancement possible due to the {CSI} at the transmitter in the finite blocklength regime. The results are further elucidated via numerical examples.","Title: Algorithms for Nash and Pareto Equilibria for Resource Allocation in Multiple Femtocells.\nYear: 2017\n\nAbstract: We consider a cellular system with multiple Femtocells operating in a Macrocell. They are sharing a set of communication channels. Each Femtocell has multiple users requiring certain minimum rate guarantees. Each channel has a peak power constraint to limit interference to the Macro Base Station (BS). We formulate the problem of channel allocation and power control at the Femtocells as a noncooperative Game. We develop decentralized algorithms to obtain a Coarse Correlated equilibrium that satisfies the QoS of each user. If the QoS of all the users cannot be satisfied, then we obtain a fair equilibrium. Finally we also provide a decentralized algorithm to reach a Pareto and a Nash Bargaining solution which has a much lower complexity than the algorithm to compute the NE.","Title: A Distributed Scheduling Algorithm to Provide Quality-of-Service in Multihop Wireless Networks.\nYear: 2017\n\nAbstract: Control of multihop Wireless networks in a distributed manner while providing end-to-end delay requirements for different flows, is a challenging problem. Using the notions of Draining Time and Discrete Review from the theory of fluid limits of queues, an algorithm that meets delay requirements to various flows in a network is constructed. The algorithm involves an optimization which is implemented in a cyclic distributed manner across nodes by using the technique of iterative gradient ascent, with minimal information exchange between nodes. The algorithm uses time varying weights to give priority to flows. The performance of the algorithm is studied in a network with interference modelled by independent sets.","Title: Learning Equilibria For Power Allocation Games In Cognitive Radio Networks With A Jammer\nYear: 2016\n\nAbstract: In this paper, competitive interactions between a secondary transmitter-receiver pair and a jammer are investigated in a distributed manner over N orthogonal frequency bands, each of which is licensed to a primary user (PU). There is an interference restriction at the secondary receiver (SR) and power budget constraints at the secondary transmitter (ST) and the jammer. In addition, the ST (jammer) does not know the channels' gains of the jammer (ST). After sensing each of the frequency bands, the ST and the jammer decide how to transmit information and how to block these transmissions respectively. In this respect, both the ST and the jammer incur a communication cost and the SR sends an acknowledgment (ACK) if it decodes the information correctly. Otherwise, it sends a negative ACK (NACK). The strategic and distributed power allocation between the ST and the jammer is modeled as a stochastic game in which we employ a multiplicative weight no-regret learning mechanism to obtain an equilibrium point.","Title: Detection diversity of spatio-temporal data using Pitman's efficiency for low SNR regimes\nYear: 2016\n\nAbstract: In this work, we use Pitman's efficiency to characterize the diversity of a spatio-temporal distributed detection system. Pitman's efficiency directly measures the detection ability of the data at low signal to noise ratios (SNRs). We study how the statistics of spatio-temporal distributed data affect the diversity of the system. We derive the diversity measure for the optimal likelihood ratio test (LRT) statistic for slow fading channels. Moreover, we capture the heterogeneity of channel gains and channel noise variances in our diversity expressions. Then, we compare our diversity measure with another one that was also proposed for low SNRs.","Title: Neuro-fuzzy approach in business applications: a decade survey.\nYear: 2017\n\nAbstract: This paper presents a survey of the application-based research on neuro-fuzzy systems (NFS) in business on account of the research articles published in various reputed international journals and conferences during the last decade (2005-2014). The application of the NFS in different business domains has diversified enormously during this period and NFS has emerged as a dominant technique for addressing various research problems in various business domains. On the basis of an in-depth review of these research articles, we have identified finance, marketing, distribution, business planning, information systems, production and operations as the main business application domains of NFS during this period. The impact of NFS in different business domains and the trends in this application-based research are presented and discussed in this paper. For each of these years, this paper also explores the various innovations in NFS methodologies employed by the researchers to tackle different business problems. Furthe...","Title: A review on the applications of neuro-fuzzy systems in business.\nYear: 2018\n\nAbstract: This paper presents a review of the application of neuro-fuzzy systems (NFS) in business on the basis of the research articles issued in various reputed international journals and conferences during 2005–2015. The use of NFS for tackling various real world problems in different business domains has diversified significantly during this period. In effect NFS has emerged as a dominant technique for addressing various difficult research problems in business. Based on a detailed review of these research papers we have identified finance, marketing, distribution, business planning, information systems, production and operations as the main business application domains of NFS during this period. This paper also discusses the impact of NFS in various business domains and the trend of this application based research during this period. This paper also surveys the various innovations in NFS methodologies employed by the researchers to deal with different business problems in each of these years. Moreover the paper includes some articles published during 2016 in several international journals to present the latest progress in the application of NFS in various business domains.","Title: Optimal Sensor Collaboration for Parameter Tracking Using Energy Harvesting Sensors.\nYear: 2018\n\nAbstract: In this paper, we design an optimal sensor collaboration strategy among neighboring nodes while tracking a time-varying parameter using wireless sensor networks in the presence of imperfect communication channels. The sensor network is assumed to be self-powered, where sensors are equipped with energy harvesters that replenish energy from the environment. In order to minimize the mean square estim...","Title: On Sequential Random Distortion Testing of Non-Stationary Processes.\nYear: 2018\n\nAbstract: In this work, we propose a non-parametric sequential hypothesis test based on random distortion testing (RDT). RDT addresses the problem of testing whether or not a random signal, Ξ, observed in independent and identically distributed (i.i.d) additive noise deviates by more than a specified tolerance, τ, from a fixed model, ξ0. The test is non-parametric in the sense that the underlying signal dis...","Title: Bounds on Channel Capacity of a Fiber Optic Channel with Memory\nYear: 2018\n\nAbstract: The following topics are dealt with: learning (artificial intelligence); computational complexity; optimisation; probability; graph theory; channel coding; array signal processing; stochastic processes; decoding; millimetre wave communication.","Title: Quality-of-Service in Multihop Wireless Networks: Diffusion Approximation.\nYear: 2018\n\nAbstract: We consider a multihop wireless system. There are multiple source-destination pairs. The data from a source may have to pass through multiple nodes. We obtain a channel scheduling policy which can guarantee end-to-end mean delay for the different traffic streams. We show the stability of the network for this policy by convergence to a fluid limit. It is intractable to obtain the stationary distribution of this network. Thus we also provide a diffusion approximation for this scheme under heavy traffic. We show that the stationary distribution of the scaled process of the network converges to that of the Brownian limit. This theoretically justifies the performance of the system. We provide simulations to verify our claims.","Title: An interpretable neuro-fuzzy approach to stock price forecasting.\nYear: 2019\n\nAbstract: Stock price prediction is a complex and difficult task due to the chaotic behavior and high uncertainty in stock market prices. The design of a highly accurate, simple and intelligible forecasting model is of prime importance in this field. With this aim, a number of research studies have employed fuzzy rule-based systems for stock price forecasting. But the main focus has been on obtaining fuzzy systems with high accuracy and the interpretability aspect has been overlooked due to the assumption that the fuzzy rule-based systems are implicitly interpretable in the form of fuzzy rules which is not essentially true. This paper proposes an efficient and interpretable neuro-fuzzy system for stock price prediction using multiple technical indicators with focus on interpretability–accuracy trade-off. The interpretability of the system is ensured by: (1) rule base reduction via selection of the best rules using rule performance criteria to obtain an efficient and a compact rule base which is easily comprehendible and (2) constrained learning during model optimization stage so that simple constraints are imposed on the updates of fuzzy set parameters due to which the system remains interpretable and forecasting accuracy is not compromised. For experimental evaluation of the proposed system, daily stock data of Bombay Stock Exchange, CNX Nifty and S&P 500 stock indices are used. The simulation results show that the proposed system obtains a better balance between accuracy and interpretability than two other artificial intelligence techniques and two statistical techniques commonly used in stock price prediction.","Title: On Random Distortion Testing Based Sequential Non-Parametric Hypothesis Testing<sup>*</sup>\nYear: 2018\n\nAbstract: In this work, we propose a new method for sequential binary hypothesis testing. The approach is non-parametric in the sense that it does not assume any knowledge of signal distributions under each hypothesis. The proposed framework is based on Random distortion testing (RDT) which addresses the problem of testing whether or not a random signal, deviates by more than a specified tolerance, $\\tau$, from a fixed value, $\\xi_{0}$. We first state the problem setup and then discuss earlier approaches to solve the problem. We then propose a new sequential algorithm, T-SeqRDT, which is shown to control the probabilities of error while reducing the number of samples required to make a decision compared to the fixed-sample-size version of RDT. Finally, via simulations we compare T-SeqRDT to other algorithms and show its robustness compared to standard likelihood ratio based approaches.","Title: An asymptotic approximation for TCP CUBIC\nYear: 2019\n\nAbstract: AbstractIn this paper, we derive an expression for computing the average window size of a single TCP CUBIC connection under random losses. For this we consider a throughput expression for TCP CUBIC computed earlier under deterministic periodic packet losses. We validate this expression theoretically. We then use insights from the deterministic loss-based model to scale appropriately a sequence of Markov chains with random losses indexed by the probability of loss p. We show that this sequence converges to a limiting Markov chain as p tends to 0. The stationary distribution of the limiting Markov chain is then used to derive the average window size for small packet error rates. We then use a simple approximation to extend our current results with negligible queuing to a setup with multiple connections and non-negligible queuing. We validate our model and approximations via simulations.","Title: Towards An Online Energy Allocation Policy For Distributed Estimation With Sensor Collaboration Using Energy Harvesting Sensors\nYear: 2016\n\nAbstract: We study an energy allocation problem for distributed estimation with sensor collaboration, where collaboration refers to the act of sharing measurements with neighboring sensors prior to transmission to the fusion center, and the sensors are equipped with energy harvesters to replenish their power from the environment. Based on the statistics of the harvested energy and dynamics of energy flow at each sensor, we propose a provably efficient online energy allocation policy for distributed estimation with sensor collaboration. The proposed online policy relies on solving an offline non-convex optimization problem, in which the estimation distortion is minimized subject to energy and network topology constraints. We employ semidefinite programming to find the globallyoptimal solution of the non-convex problem. We show that the proposed online policy is asymptotically consistent and provide mean square error of the optimal offline solution over an infinite time horizon.","Title: Novel benchmark database of digitized and calibrated cervical cells for artificial intelligence based screening of cervical cancer.\nYear: 2016\n\nAbstract: The primary objective of this research work is to develop a novel benchmark database of digitized and calibrated, cervical cells obtained from slides of Papanicolaou smear test, which is done for screening of cervical cancer. This database can serve as a potential tool for designing, developing, training, testing and validating various artificial intelligence based systems for prognosis of cervical cancer by characterization and classification of Papanicolaou smear images. The database can also be used by other researchers for comparative analysis of working efficiencies of various machine learning and image processing algorithms. The database can be obtained by sending a request to the corresponding author or can be downloaded from http://digitalpapsmeardb.in/. Besides developing a rich machine learning database we have also presented a novel artificial intelligence based hybrid ensemble technique for efficient screening of cervical cancer by automated analysis of Papanicolaou smear images. The correct and timely diagnosis of cervical cancer is one of the major problems in the medical world. From the literature it has been found that different pattern recognition techniques can help them to improve in this domain. Papanicolaou smear (also referred to as Pap smear) is a microscopic examination of samples of human cells scraped from the lower, narrow part of the uterus, called cervix. A sample of cells after being stained by using Papanicolaou method is analyzed under microscope for the presence of any unusual developments indicating any precancerous and potentially precancerous developments. Abnormal findings, if observed are subjected to further precise diagnostic subroutines. Examining the cell images for abnormalities in the cervix provides grounds for provision of prompt action and thus reducing incidence and deaths from cervical cancer. It is the most popular technique used for screening of cervical cancer. Pap smear test, if done with a regular screening programs and proper follow-up, can reduce cervical cancer mortality by up to 80 % (Arbyn et al. Ann Oncol 21:48–458, 2010). The contribution of this paper is that we have created a rich machine learning database of quantitatively profiled and calibrated cervical cells obtained from Pap-smear test slides. The database so created consists of data of about 200 clinical cases (8091 cervical cells), which have been obtained from multiple health care centers, so as to ensure diversity in data. The Pap-smear slides were processed using a multi-headed digital microscope and images of cervical cells were obtained, which were then passed through various data preprocessing subroutines. After preprocessing the cells were morphologically profiled and scaled to obtain separate quantitative measurements of various features of cytoplasm and nucleus respectively. The cells in the database were carefully classified in different corresponding classes according to the latest 2001-Bethesda system of classification, by multiple cytotechnicians and histopathologists. In addition to this, we have also pioneered to apply a novel hybrid ensemble system to this database in order to evaluate the effectiveness of both novel database and novel hybrid ensemble technique to screen cervical cancer by categorization of Pap smear data. The paper also presents a comparative analysis of multiple artificial intelligence based classification algorithms for prognosis of cervical cancer. For evaluating the effectiveness and correctness of the digital database prepared in this work, authors implemented this database for training, testing and validating fifteen different artificial intelligence based machine learning algorithms. All the algorithms trained with this database presented commendable efficiency in screening of cervical cancer. For two-class problem all the algorithms trained with the digital database showed the efficiencies in the range of about 93 to 95 % while as in case of multi class problem algorithms expressed the efficiencies in the range of about 69 to 78 %. The results indicate that the novel digital database prepared in this work can be efficiently used for developing new machine learning based techniques for automated screening of cervical cancer. The results also indicate that hybrid ensemble technique is an efficient method for classification of pap-smear images and hence can be effectively used for diagnosis of cervical cancer. Among all the algorithms implemented, the hybrid ensemble approach outperformed and expressed an efficiency of about 98 % for 2-class problem and about 86 % for 7-class problem. The results when compared with the all the standalone classifiers were significantly better for both two-class and multi-class problems.","Title: Artificial neural network based screening of cervical cancer using a hierarchical modular neural network architecture (HMNNA) and novel benchmark uterine cervix cancer database\nYear: 2019\n\nAbstract: The work reported in this paper presents a novel hierarchical modular neural network architecture (HMNNA) for automated screening of cervical cancer. HMNNA consists of three neural networks trained specifically on different areas of problem space under consideration, and the trained networks are then arranged in a tree structure forming hierarchical modular neural network architecture. The three specialized neural networks are trained by Levenberg–Maarquardt neural network algorithm. As compared to the standard back propagation algorithm, Levenberg–Maarquardt is fast and stable for convergence with only one drawback, i.e., storage requirement for estimated Hessian Matrix. For training and testing of HMNNA, a huge primary database is created which contains 8091 cervical cell images pertaining to 200 clinical cases collected from two health care institutions of northern India. The raw cases of cervical cancer in the form of Pap smear slides were photographed under a multi-headed digital microscope. Individual cells were manually cropped off from these slide images which were then passed through a feature extraction module for morphological profiling. Each cell was calibrated on the basis of 40 features from both cytoplasm and nucleus. After profiling, these cells were vigilantly assigned cell classes as per the latest 2001-Bethesda system of cervical cancer cell classification, by trained cytotechnicians and histopathologists. HMNNA is also trained and tested on the Herlev Benchmark dataset created by the Denmark University, which consists of 1417 cervical cancer cells. Both the datasets have seven classes of diagnosis, i.e., superficial squamous, intermediate squamous, columnar, mild dysplasia, moderate dysplasia, severe dysplasia, and carcinoma in situ, corresponding to the level of abnormality in cervical cells. These datasets are available in public domain at http://digitalpapsmeardb.in/ and http://mde-lab.aegean.gr/index.php/downloads. The screening potential of the HMNNA is compared with 25 well-known machine learning algorithms available in MatlabR2016 (Machine learning and statistics toolbox 10.2) and monolithic neural network algorithms available in Matlab neural network pattern recognition toolbox. The HMNNA outperformed in all the 25 algorithms for both the datasets. For the Novel Benchmark database, it produced a classification accuracy of 95.32% with an F-value of 0.949310 and classification accuracy of 88.41% with an F-value of 0.89145 for the Herlev dataset. The screening potential of HMNNA was also evaluated and compared with the other diagnostic systems available in the recently published literature and was found to be performing much better than the counterparts on multiple parameters of performance evaluation.","Title: Cross-App Tracking via Nearby Bluetooth Low Energy Devices.\nYear: 2018\n\nAbstract: Today an increasing number of consumer devices such as head phones, wearables, light bulbs and even baseball bats, are Bluetooth-enabled thanks to the widespread support of the technology by phone manufacturers and mobile operating system vendors. The ability for any device to seamlessly connect and exchange information with smartphones via Bluetooth Low Energy (BLE) protocol promises unlimited room for innovation. However, it also brings about new privacy challenges. We show that the BLE protocol together with the Bluetooth permission model implemented in the Android and iOS operating systems can be used for cross-app tracking unbeknownst to the individuals.\n\nSpecifically, through experiments and analyses based on real-world smartphone data we show that by listening to advertising packets broadcasted by nearby BLE-enabled devices and recording information contained in them, app developers can derive fairly unique \"fingerprints\" for their users, which can be used for cross-app tracking, i.e., linking pseudonymous users of different apps to each other. We demonstrate that privacy protections put in place by the Bluetooth Special Interest Group, Google, and Apple are not sufficient to prevent such fingerprinting or to make cross-app tracking difficult to execute.\n\nOur main contribution is to demonstrate the feasibility of cross-app tracking using nearby BLE and raise awareness that changes are needed in order to prevent it from becoming widespread. We also propose mitigation strategies to decrease the feasibility of tracking using nearby BLE devices while preserving the utility of the BLE technology.","Title: Queuing Theoretic Models for Multicast and Coded-Caching in Downlink Wireless Systems.\nYear: 2018\n\nAbstract: We consider a server connected to $L$ users over a shared finite capacity link. Each user is equipped with a cache. File requests at the users are generated as independent Poisson processes according to a popularity profile from a library of $M$ files. The server has access to all the files in the library. Users can store parts of the files or full files from the library in their local caches. The server should send missing parts of the files requested by the users. The server attempts to fulfill the pending requests with minimal transmissions exploiting multicasting and coding opportunities among the pending requests. We study the performance of this system in terms of queuing delays for the naive multicasting and several coded multicasting schemes proposed in the literature. We also provide approximate expressions for the mean queuing delay for these models and establish their effectiveness with simulations.","Title: Second Order and Moderate Deviation Analysis of a Block Fading Channel with Deterministic and Energy Harvesting Power Constraints.\nYear: 2019\n\nAbstract: We consider a block fading additive white Gaussian noise (AWGN) channel with perfect channel state information (CSI) at the transmitter and the receiver. First, for a given codeword length and non-vanishing average probability of error, we obtain lower and upper bounds on the maximum transmission rate. We derive bounds for three kinds of power constraints inherent to a wireless transmitter. These include the canonical peak power constraint and average power constraint. In addition, we consider a time varying peak power constraint imposed by an emph{energy harvesting device}-a mechanism that powers many modern-day wireless transmitters. The bounds characterize emph{second order} deviation of finite blocklength coding rates from the channel capacity, which is in turn achieved by textit{water-filling} power allocation across time. The bounds obtained also indicate the rate enhancement possible due to CSI at the transmitter in the finite blocklength regime. Next, we provide bounds on the optimal exponent with which error probability drops to zero when channel coding rate is simultaneously allowed to approach capacity emph{at a certain rate}, as the codeword length increases. These bounds identify what is known as the moderate deviation regime of the block fading channel. We compare the bounds numerically to bring out the efficacy of our results.","Title: A Lower Bound on Channel Capacity of a Nonlinear Fiber Optic Channel with Memory\nYear: 2018\n\nAbstract: We consider a nonlinear fiber optic channel with memory and signal dependent noise. We provide an achievable rate via an i.i.d. complex Gaussian input. This improves on an existing bound. We also argue that our bound is close to the capacity of the channel.","Title: Queueing Theoretic Models for Uncoded and Coded Multicast Wireless Networks With Caches\nYear: 2022\n\nAbstract: We consider a server connected to several users over a shared finite capacity link. Each user is equipped with a cache. File requests at the users are generated as independent Poisson processes according to a popularity profile from a fixed finite library of files. The server has access to all the files in the library. Users can store parts of the files or full files from the library in their local caches. The server should send missing parts of the files requested by the users. The server attempts to fulfill the pending requests with minimal transmissions exploiting multicasting and coding opportunities among the pending requests. We consider a queue in which requests for the same file from different users is merged and transmitted simultaneously to all the requested users. We study and compare the performance of this queuing system in terms of queuing delays when LRU caches are used and when coded caching schemes proposed in the literature are used. We provide approximate expressions for the mean queuing delay for these models and establish their effectiveness with simulations. We extend the analysis to the case when transmission errors are also taken into account."],"string":"[\n \"Title: Theoretical analysis of high-speed multiple TCP connections through multiple routers.\\nYear: 2013\\n\\nAbstract: We study a system of multiple routers traversed by multiple TCP connections using TCP New Reno, CUBIC and Compound. More than one router may be congested. To analyze this system we will use earlier theoretical models of TCP New Reno and CUBIC but develop a new model of TCP Compound experiencing random packet losses and queuing delays. We model the router queues as M/GI/1 queues with arrival rates controlled by TCP window flow control. We also look at an alternate approach assuming proportional fairness of TCP to find the throughputs of the multiple TCP connections. These approximations are validated through comparison with ns-2 simulations.\",\n \"Title: Modelling and analysis of New Coolstreaming for P2P IPTV.\\nYear: 2012\\n\\nAbstract: Peer to peer networks are being used extensively nowadays for file sharing, video on demand and live streaming. For IPTV, delay deadlines are more stringent compared to file sharing. Coolstreaming was the first P2P IPTV system. In this paper, we model New Coolstreaming (newer version of Coolstreaming) via a queueing network. We use two time scale decomposition of Markov chains to compute the stationary distribution of number of peers and the expected number of substreams in the overlay which are not being received at the required rate due to parent overloading. We also characterize the end-to-end delay encountered by a video packet received by a user and originated at the server. Three factors contribute towards the delay. The first factor is the mean shortest path length between any two overlay peers in terms of overlay hops of the partnership graph which is shown to be O (log n) where n is the number of peers in the overlay. The second factor is the mean number of routers between any two overlay neighbours which is seen to be at most O (log N-I) where N-I is the number of routers in the internet. Third factor is the mean delay at a router in the internet. We provide an approximation of this mean delay E [W]. Thus, the mean end to end delay in New Coolstreaming is shown to be upper bounded by O [(log E [N]) (log N-I) E (W)] where E [N] is the mean number of peers at a channel.\",\n \"Title: Distributed Joint Source-Channel Coding for Functions over a Multiple Access Channel\\nYear: 2009\\n\\nAbstract: In this paper we provide sufficient conditions for lossy transmission of functions of correlated data over a multiple access channel (MAC). The conditions obtained can be shown as generalized version of Yamamoto's result [28]. We also obtain efficient joint source-channel coding schemes for transmission of discrete and continuous alphabet sources to recover the function values.\",\n \"Title: A stochastic control approach for scheduling multimedia transmissions over a polled multiaccess fading channel\\nYear: 2006\\n\\nAbstract: We develop scheduling strategies for carrying multimedia traffic over a polled multiple access wireless network with fading. We consider a slotted system with three classes of traffic (voice, streaming media and file transfers). A Markov model is used for the fading and also for modeling voice packet arrivals and streaming arrivals. The performance objectives are a loss probability for voice, mean network delay for streaming media, and time average throughput for file transfers. A central scheduler (e.g., the access point in a single cell IEEE 802.11 wireless local area network (WLAN)) is assumed to be able to keep track of all the available state information and make the scheduling decision in each slot (e.g., as would be the case for PCF mode operation of the IEEE 802.11 WLAN). The problem is modeled as a constrained Markov decision problem. By using constraint relaxations (a linear relaxation and Whittle type relaxations) an index based policy is obtained. For the file transfers the decision problem turns out to be one with partial state information. Numerical comparisons are provided with the performance obtained from some simple policies.\",\n \"Title: Performance analysis of battery power management schemes in wireless mobile devices.\\nYear: 2002\\n\\nAbstract: In this paper, we analyze the performance of battery power management schemes in wireless mobile devices using a queueing theory approach. We model the battery as a server with finite service capacity and data packets as customers to be served. With an intent to exploit the recharging capability of the battery when left idle, we allow the battery to go on intentional vacations during which the battery can recharge itself. The recharge thus built up can effectively increase the number of customers served (in other words, battery life can be extended). Such improved battery life performance would, however, come at the expense of increased packet delay performance. We quantify the battery life gain versus delay performance trade-off in this approach through analysis and simulations. By considering a continuous recharge model of the battery, we derive expressions for the number of customers served and the mean delay for an M/GI/1 queueing system without and with server vacations. We show that allowing intentional vacations during busy periods helps to increase battery life, and that this approach can be beneficial when applied on traffic of delay-tolerant applications. We also propose a packet delay constrained power saving algorithm that will exploit the recharge phenomenon when packet delay constraints are imposed.\",\n \"Title: Reliable estimation via simulation\\nYear: 1995\\n\\nAbstract: Leta ands denote the inter arrival times and service times in aGI/GI/1 queue. Let a(n), s(n) be the r.v.s. with distributions as the estimated distributions ofa ands from iid samples ofa ands of sizesn. Letw be a r.v. with the stationary distribution p of the waiting times of the queue with input(a,s). We consider the problem of estimatingE[wa], a> 0 and a via simulations when (a(n),s(n)) are used as input. Conditions for the accuracy of the asymptotic estimate, continuity of the asymptotic variance and uniformity in the rate of convergence to the estimate are obtained. We also obtain rates of convergence for sample moments, the empirical process and the quantile process for the regenerative processes. Robust estimates are also obtained when an outlier contaminated sample ofa ands is provided. In the process we obtain consistency, continuity and asymptotic normality of M-estimators for stationary sequences. Some robustness results for Markov processes are included.\",\n \"Title: Cooperative Sequential Spectrum Sensing Algorithms for OFDM\\nYear: 2010\\n\\nAbstract: This paper considers the problem of spectrum sensing in cognitive radio\\nnetworks when the primary user employs Orthogonal Frequency Division\\nMultiplexing (OFDM). We develop cooperative sequential detection algorithms\\nbased on energy detectors and the autocorrelation property of cyclic prefix\\n(CP) used in OFDM systems and compare their performances. We show that\\nsequential detection provides much better performance than the traditional\\nfixed sample size (snapshot) based detectors. We also study the effect of model\\nuncertainties such as timing and frequency offset, IQ-imbalance and uncertainty\\nin noise and transmit power on the performance of the detectors. We modify the\\ndetectors to mitigate the effects of these impairments. The performance of the\\nproposed algorithms are studied via simulations. It is shown that energy\\ndetector performs significantly better than the CP-based detector, except in\\ncase of a snapshot detector with noise power uncertainty. Also, unlike for the\\nCP-based detector, most of the above mentioned impairments have no effect on\\nthe energy detector.\",\n \"Title: Performance Analysis of a Cooperative System with Rateless Codes and Buffered Relays\\nYear: 2011\\n\\nAbstract: In a cooperative relay-assisted communication system that uses rateless codes, packets get transmitted from a source to a destination at a rate that depends on instantaneous channel states of the wireless links between nodes. When multiple relays are present, the relay with the highest channel gain to the source is the first to successfully decode a packet from the source and forward it to the des...\",\n \"Title: Optimal energy management policies for energy harvesting sensor nodes\\nYear: 2008\\n\\nAbstract: We study a sensor node with an energy harvesting source. The generated energy can be stored in a buffer. The sensor node periodically senses a random field and generates a packet. These packets are stored in a queue and transmitted using the energy available at that time. We obtain energy management policies that are throughput optimal, i.e., the data queue stays stable for the largest possible data rate. Next we obtain energy management policies which minimize the mean delay in the queue. We also compare performance of several easily implementable sub-optimal energy management policies. A greedy policy is identified which, in low SNR regime, is throughput optimal and also minimizes mean delay.\",\n \"Title: On Optimal Distributed Joint Source-Channel Coding for Correlated Gaussian Sources over Gaussian Channels\\nYear: 2009\\n\\nAbstract: We consider the problem of distributed joint source-channel coding of\\ncorrelated Gaussian sources over a Gaussian Multiple Access Channel (GMAC).\\nThere may be side information at the decoder and/or at the encoders. First we\\nspecialize a general result (for transmission of correlated sources over a MAC\\nwith side information) to obtain sufficient conditions for reliable\\ntransmission over a Gaussian MAC. This system does not satisfy the\\nsource-channel separation. We study and compare three joint source-channel\\ncoding schemes available in literature. We show that each of these schemes is\\noptimal under different scenarios. One of the schemes, Amplify and Forward (AF)\\nwhich simplifies the design of encoders and the decoder, is optimal at low SNR\\nbut not at high SNR. Another scheme is asymptotically optimal at high SNR. The\\nthird coding scheme is optimal for orthogonal Gaussian channels. We also show\\nthat AF is close to the optimal scheme for orthogonal channels even at high\\nSNR.\",\n \"Title: Efficient Energy Management Policies for Networks with Energy Harvesting Sensor Nodes\\nYear: 2008\\n\\nAbstract: We study sensor networks with energy harvesting nodes. The generated energy at a node can be stored in a buffer. A sensor node periodically senses a random field and generates a packet. These packets are stored in a queue and transmitted using the energy available at that time at the node. For such networks we develop efficient energy management policies. First, for a single node, we obtain policies that a re throughput optimal, i.e., the data queue stays stable for the largest possible data rate. Next we obtain energy management policies which minimize the mean delay in the queue. We also compare performance of several easily implementable sub- optimal policies. A greedy policy is identified which, in low SNR regime, is throughput optimal and also minimizes mean delay. Next using the results for a single node, we develop efficient MAC policies.\",\n \"Title: Joint Source-Channel Coding on a Multiple Access Channel with Side Information\\nYear: 2009\\n\\nAbstract: We consider the problem of transmission of several distributed correlated\\nsources over a multiple access channel (MAC) with side information at the\\nsources and the decoder. Source-channel separation does not hold for this\\nchannel. Sufficient conditions are provided for transmission of sources with a\\ngiven distortion. The source and/or the channel could have continuous alphabets\\n(thus Gaussian sources and Gaussian MACs are special cases). Various previous\\nresults are obtained as special cases. We also provide several good joint\\nsource-channel coding schemes for discrete sources and discrete/continuous\\nalphabet channel.\",\n \"Title: An analytical model for capacity evaluation of VoIP on HCCA and TCP file transfers over EDCA in an IEEE 802.11e WLAN\\nYear: 2006\\n\\nAbstract: In the context of the IEEE 802.11e standard for WLANs, we provide an analytical model for obtaining the maximum number of VoIP calls that can be supported on HCCA, such that the delay QoS constraint of the accepted calls is met, when TCP downloads are coexistent on EDCA. In this scenario, we derive the TCP download throughput by using an analytical model for the case where only TCP sessions are present in the WLAN. We show that the analytical model for combined voice and TCP transfers provides accurate results in comparison with simulations (using ns-2).\",\n \"Title: Stability and Analysis of TCP Connections with RED Control and Exogenous Traffic\\nYear: 2004\\n\\nAbstract: In this paper we study the stability and performance of a system involving several TCP connections passing through a tandem of RED controlled queues each of which has an incoming exogenous stream. The exogenous stream, representing the superposition of all incoming UDP connections into a queue, has been modeled as an MMPP stream. We consider both the TCP Tahoe and the TCP Reno versions. We start with the analysis of a single TCP connection sharing a RED controlled queue with an exogenous stream. The effect of the exogenous stream (which is almost always present in large networks) is to cause the system to converge to a stationary distribution from any initial conditions. This stability result holds good for any work conserving discipline. We also obtain the performance indices of the system; specifically the goodputs and the mean sojourn times of the various connections. The complexity involved in computation of performance indices for the system is reduced by approximating the evolution of the average queue length process of the RED queue by a deterministic ODE. Then, by using a decomposition approach of two time scales, we reduce the study of the system to that of a simplified one for which the performance measures can be obtained under stationarity. Finally, we extend the above results to the case when multiple TCP connections share a RED controlled queue with an exogenous stream and to the case when a TCP connection passes through several RED controlled tandem queues each of which has an incoming exogenous stream. We also consider an example of multiple TCPs passing through a tandem of queues. A number of simulation results have been provided which support the analysis.\",\n \"Title: Comparative analysis of machine learning techniques in prognosis of type II diabetes.\\nYear: 2014\\n\\nAbstract: Artificial Intelligence (AI) is now a days gaining immense importance and is becoming a key technology in many fields ranging from banking industry, to travel industry, to communication industry, and to robotic industry. The use of AI in medical diagnosis too is becoming increasingly popular and has been widely used in the diagnosis of tumors, cancers, hepatitis, lung diseases, etc. Numerous algorithms have been designed that help in the process of decision making by analyzing the hidden patterns in previously held information. The main objective of this manuscript is to apply multiple algorithms to a problem in the domain of medical diagnosis and analyze their efficiency in predicting the results. The problem selected for the study is the diagnosis of diabetes. Authors have identified ten parameters that play an important role in diabetes and prepared a rich database of training data which served as the backbone of the prediction algorithms. Keeping in view this training data, authors implemented three algorithms [Naïve Bayes, artificial neural networks (ANN), and K-nearest neighbors (KNN)] and developed prediction models. To calculate the efficiency, the results of prediction system were compared with the actual medical diagnosis of the subjects. The results indicate that the ANN is the best predictor with the accuracy of about 96 % which was followed by Naïve Bayes networks having an accuracy of about 95 % and the KNN came to be the worst predictor having an accuracy of about 91 %.\",\n \"Title: A finite buffer queue with priorities\\nYear: 2002\\n\\nAbstract: We consider a queue with finite buffer where the buffer size limits the amount of work that can be stored in the queue. The arrival process is a Poisson or a Markov modulated Poisson process. The service times (packet lengths) are i.i.d. with a general distribution. Our queue models the systems in the Internet more realistically than the usual M/GI/1/K queue which restricts the number of packets in the buffer rather than the buffer content (the number of bits). We obtain the stability, the rates of convergence to the stationary distribution and functional limit theorems for this system. In addition, we also obtain algorithms to compute the stationary density of the workload process, the waiting times and the probability of packet loss. Next, we study the queue with two priority classes. The higher priority traffic has preemptive-resume priority. For sharing the buffer, we consider two cases. In the first case, the buffer is shared by both the classes without any priority. In the second case, the buffer is partitioned into two groups, one reserved for each class. For this system also we obtain all the results mentioned for the single class traffic.\",\n \"Title: Stability and continuity of polling systems\\nYear: 1994\\n\\nAbstract: The stability of a polling system with exhaustive service and a finite number of users, each with infinite buffers is considered. The arrival process is more general than a Poisson process and the system is not slotted. Stochastic continuity of the stationary distributions, rates of convergence and functional limit theorems for the queue length and waiting time processes have also been proved. The results extend to the gated service discipline.\",\n \"Title: Scheduling Under Fading and Partial Channel Information\\nYear: 2012\\n\\nAbstract: We consider a scheduler for the downlink of a wireless channel when only partial channel-state information is available at the scheduler. We characterize the network stability region and provide two throughput-optimal scheduling policies. We also derive a deterministic bound on the mean packet delay in the network. Finally, we provide a throughput-optimal policy for the network under QoS constraints when real-time and rate-guaranteed data traffic may be present.\",\n \"Title: Providing QoS to TCP and Real Time Connections in the Internet\\nYear: 2004\\n\\nAbstract: We consider a system where streaming and/or real time applications, using the UDP protocol pass through a bottleneck router. Several persistent and non persistent TCP connections may also be passing through that router. Using the rate control at the UDP sources and choosing the RED parameters appropriately, we obtain pre-specified delays, little delay jitter, no packet loss, 100% channel efficiency, pre-specified throughput for the TCP and UDP streams and little rate fluctuation. We verify our control scheme by extensive simulations. Results are extended to a tandem of queues.\",\n \"Title: Understanding User's Emotional Engagement to the Contents on a Smartphone Display: Psychiatric Prospective\\nYear: 2013\\n\\nAbstract: Mobile phones are a ubiquitous and preferred communication, entertainment, and information access platform. Smartphones may provide an opportunity to better assess mood and behavior and to provide intervention timely, economical, rapid and effective intervention for those with mental disorders. This is an important target because behavioral health problems are associated with many of the medical disorders most responsible for morbidity and cost. Today, psychiatrists seek for various channels of mobile technology that can reduce evaluation costs and increase accuracy and also facilitate ubiquitous longitudinal monitoring of treatment and outcome measures on patients' smartphone. Facial expression recognition is one of the active research areas in the field of psychiatry to evaluate a patient's emotional health. Smartphone technology for recognizing facial expression of emotions is still emerging and offers an open platform for the research areas such as ubiquitous intelligence and computing. In this research, we present a framework to track user's emotional engagement to videos played on a smartphone. The presented framework processes user's video recorded from the front-facing camera of a smartphone and tracks facial features to detect joyful durations induced by the played videos. We also conducted subject studies on healthy individuals to evaluate the applied approach of emotional engagement. We believe that the presented results are promising and present a valuable insight to build ubiquitous intelligent systems that can help various areas of psychiatric research.\",\n \"Title: Joint Routing, Scheduling And Power Control For Multihop Wireless Networks With Multiple Antennas\\nYear: 2011\\n\\nAbstract: We consider the problem of Joint Routing, Scheduling and Power-control (JRSP) problem for multihop wireless networks (MHWN) with multiple antennas. We extend the problem and a (sub-optimal) heuristic solution method for JRSP in MHWN with single antennas. We present an iterative scheme to calculate link capacities(achievable rates) in the interference environment of the network using SINR model. We then present the algorithm for solving the JRSP problem. This completes a feasible system model for MHWN when nodes have multiple antennas. We show that the gain we achieve by using multiple antennas in the network is linear both in optimal performance as well as heuristic algorithmic performance.\",\n \"Title: Joint Source-Channel Coding over a Fading Multiple Access Channel with Partial Channel State Information\\nYear: 2009\\n\\nAbstract: In this paper we address the problem of transmission of correlated sources over a fast fading multiple access channel (MAC) with partial channel state information available at both the encoders and the decoder. We provide sufficient conditions for transmission with given distortions. Next these conditions are specialized to a Gaussian MAC (GMAC). We provide the optimal power allocation strategy and compare the strategy with various levels of channel state information.\",\n \"Title: Estimating traffic parameters in queueing systems with local information\\nYear: 1998\\n\\nAbstract: In ATM networks a new connection is accepted if the CAC (call acceptance controller) at the entering node decides that the network has the requisite resources for the incoming traffic. For this, the CAC will need to monitor the network congestion based on the local information available to it. In this paper we propose several schemes that the CAC can use to estimate the traffic of the users on the various routes in the network by sending a ‘probing’ stream. First we consider a single node where the probing stream could be arbitrary while the total interfering traffic is a Poisson process. Knowing the mean service time of the interfering traffic and the delays experienced by the probing stream we provide algorithms to estimate the arrival rate of the interfering traffic. We model the node as a continuous time as well as a discrete time queue. Then we generalize the assumptions on the interfering traffic to make the overall traffic at the node a general stationary ergodic stream. For the Poisson interfering traffic we also consider a tandem of queues. Finally, for a product form Kelly network we provide estimates of the arrival rates of interfering traffic and the service rates of customers on the route of the probing stream of the CAC. These estimates are also used to provide the optimal ‘reshaping’ of the traffic stream of a user based on the delays experienced by the user in the network.\",\n \"Title: Joint power control, scheduling and routing for multihop energy harvesting sensor networks\\nYear: 2009\\n\\nAbstract: We study wireless multihop energy harvesting sensor net works employed for random field estimation. The sensors sense the random field and generate data that is to be sent to a fusion node for estimation. Each sensor has an energy harvesting source and can operate in two modes: Wake and Sleep. We consider the problem of obtaining jointly optimal power control, routing and scheduling policies that ensure a fair utilization of network resources. This problem has a high computational complexity. Therefore, we develop a computationally efficient suboptimal approach to obtain good solutions to this problem. We study the optimal solution and performance of the suboptimal approach through some numerical examples.\",\n \"Title: Performance analysis of a slotted-ALOHA protocol on a capture channel with fading\\nYear: 2000\\n\\nAbstract: We consider the slotted ALOHA protocol on a channel with a capture effect. There are M users each with an infinite buffer. If in a slot, i packets are transmitted, then the probability of a successful reception of a packet is q_i. This model contains the CDMA protocols as special cases. We obtain sufficient rate conditions, which are close to necessary for stability of the system, when the arrival streams are stationary ergodic. Under the same rate conditions, for general regenerative arrival streams, we obtain the rates of convergence to stationarity, finiteness of stationary moments and various functional limit theorems. Our arrival streams contain all the traffic models suggested in the recent literature, including the ones which display long range dependence. We also obtain bounds on the stationary moments of waiting times which can be tight under realistic conditions. Finally, we obtain several results on the transient performance of the system, e.g., first time to overflow and the limits of the overflow process. We also extend the above results to the case of a capture channel exhibiting Markov modulated fading. Most of our results and proofs will be shown to hold also for the slotted ALOHA protocol without capture.\",\n \"Title: Queued Cooperative Wireless Networks With Rateless Codes\\nYear: 2008\\n\\nAbstract: Cooperative communication using rateless codes, in which the source transmits an infinite number of parity bits to the destination until the receipt of an acknowledgment, has recently attracted considerable interest. It provides a natural and efficient mechanism for accumulating mutual information from multiple transmitting relays. We develop an analysis of queued cooperative relay systems that combines the communication-theoretic transmission aspects of cooperative communication using rateless codes over Rayleigh fading channels with the queuing-theoretic aspects associated with buffering messages at the relays. Relay cooperation combined with queuing reduces the message transmission times and also helps distribute the traffic load in the network, which improves throughput significantly.\",\n \"Title: An Efficient Algorithm for Cooperative Spectrum Sensing in Cognitive Radio Networks\\nYear: 2008\\n\\nAbstract: We consider the problem of Spectrum Sensing in Cogni- tive Radio Systems. We have developed a distributed algorithm that the Secondary users can run to sense the channel cooperatively. It is based on sequential detection algorithms which optimally use the past observations. We use the algorithm on secondary users with energy detectors although it can be used with matched filter and other spectrum sensing algorithms also. The algorithm provides very low detection delays and also consumes little energy. Furthermore it causes low interference to the primary users. We compare this algo- rithm to several recently proposed algorithms and show that it de- tects changes in spectrum faster than these algorithms and uses sig- nificantly less energy.\",\n \"Title: Cooperative distributed sequential spectrum sensing\\nYear: 2010\\n\\nAbstract: We consider cooperative spectrum sensing for cognitive radios. We develop an energy efficient detector with low detection delay using sequential hypothesis testing. Sequential Probability Ratio Test (SPRT) is used at both the local nodes and the fusion center. We also analyse the performance of this algorithm and compare with the simulations. Modelling uncertainties in the distribution parameters are considered. Slow fading with and without perfect channel state information at the cognitive radios is taken into account.\",\n \"Title: Performance analysis of a fluid queue with random service rate in discrete time\\nYear: 2007\\n\\nAbstract: We consider a fluid queue in discrete time with random service rate. Such a queue has been used in several recent studies on wireless networks where the packets can be arbitrarily fragmented. We provide conditions on finiteness of moments of stationary delay, its Laplace-Stieltjes transform and various approximations under heavy traffic. Results are extended to the case where the wireless link can transmit in only a few slots during a frame.\",\n \"Title: Stochastic Games on a Multiple Access Channel\\nYear: 2012\\n\\nAbstract: We consider a scenario where N users try to access a common base station. Associated with each user is its channel state and a finite queue which varies with time. Each user chooses his power and the admission control variable in a dynamic manner so as to maximize his expected throughput. The throughput of each user is a function of the actions and states of all users. The scenario considers the situation where each user knows his channel and buffer state but is unaware of the states and actions taken by the other users. We consider the scenario when each user is saturated (i.e., always has a packet to transmit) as well as the case when each user is unsaturated. We formulate the problem as a Markov game and show connections with strategic form games. We then consider various throughput functions associated with the multiple user channel and provide algorithms for finding these equilibria.\",\n \"Title: Opportunistic scheduling of wireless links\\nYear: 2007\\n\\nAbstract: We consider the problem of scheduling of a wireless channel (server) to several queues. Each queue has its own link (transmission) rate. The link rate of a queue can vary randomly from slot to slot. The queue lengths and channel states of all users are known at the beginning of each slot. We show the existence of an optimal policy that minimizes the long term (discounted) average sum of queue lengths. The optimal policy, in general needs to be computed numerically. Then we identify a greedy (one step optimal) policy, MAX-TRANS which is easy to implement and does not require the channel and traffic statistics. The cost of this policy is close to optimal and better than other well-known policies (when stable) although it is not throughput optimal for asymmetric systems. We (approximately) identify its stability region and obtain approximations for its mean queue lengths and mean delays. We also modify this policy to make it throughput optimal while retaining good performance.\",\n \"Title: Power control and transmission scheduling for network utility maximization in wireless networks\\nYear: 2007\\n\\nAbstract: We consider a joint power control and transmission scheduling problem in wireless networks with average power constraints. While the capacity region of a wireless network is convex, a characterization of this region is a hard problem. We formulate a network utility optimization problem involving time-sharing across different \\\"transmission modes,\\\" where each mode corresponds to the set of power levels used in the network. The structure of the optimal solution is a time-sharing across a small set of such modes. We use this structure to develop an efficient heuristic approach to finding a suboptimal solution through column generation iterations. This heuristic approach converges quite fast in simulations, and provides a tool for wireless network planning.\",\n \"Title: Delay Optimal Control Algorithm For A Multiaccess Fading Channel With Peak Power Constraint\\nYear: 2005\\n\\nAbstract: We consider an optimal power and rate scheduling problem for a multiaccess fading wireless channel with the objective of minimising a weighted sum of mean packet transmission delay subject to a peak power constraint. The base station acts as a controller which, depending upon the buffer lengths and the channel state of each user, allocates transmission rate and power to individual users. We assume perfect channel state information at the transmitter and the receiver. We also assume a Markov model for the fading and packet arrival processes. The policy obtained represents a form of Indexability.\",\n \"Title: An analytical model for performance evaluation of multimedia applications over EDCA in an IEEE 802.11e WLAN\\nYear: 2010\\n\\nAbstract: We extend the modeling heuristic of (Harsha et al. 2006. In IEEE IWQoS '06, pp 178 --- 187) to evaluate the performance of an IEEE 802.11e infrastructure network carrying packet telephone calls, streaming video sessions and TCP controlled file downloads, using Enhanced Distributed Channel Access (EDCA). We identify the time boundaries of activities on the channel (called channel slot boundaries) and derive a Markov Renewal Process of the contending nodes on these epochs. This is achieved by the use of attempt probabilities of the contending nodes as those obtained from the saturation fixed point analysis of (Ramaiyan et al. 2005. In Proceedings ACM Sigmetrics, '05. Journal version accepted for publication in IEEE TON). Regenerative analysis on this MRP yields the desired steady state performance measures. We then use the MRP model to develop an effective bandwidth approach for obtaining a bound on the size of the buffer required at the video queue of the AP, such that the streaming video packet loss probability is kept to less than 1%. The results obtained match well with simulations using the network simulator, ns-2. We find that, with the default IEEE 802.11e EDCA parameters for access categories AC 1, AC 2 and AC 3, the voice call capacity decreases if even one streaming video session and one TCP file download are initiated by some wireless station. Subsequently, reducing the voice calls increases the video downlink stream throughput by 0.38 Mbps and file download capacity by 0.14 Mbps, for every voice call (for the 11 Mbps PHY). We find that a buffer size of 75KB is sufficient to ensure that the video packet loss probability at the QAP is within 1%.\",\n \"Title: Queueing systems with random service rate\\nYear: 2000\\n\\nAbstract: We consider a queue with the arrival process, the service time process and the service rate process as regenerative processes. We provide conditions for its stability, rates of convergence, finiteness of moments and functional limit theorems. This queue can model a queue serving ABR and UBR traffic in an ATM switch; a multiple access channel with TDMA or CDMA protocol and fading; a queue holding best effort or controlled and guaranteed traffic in a router in the integrated service architecture (ISA) of IP-based Internet and a scheduler in the router of a differentiated service architecture. In the process we also provide results for a queue with a leaky bucket controlled bandwidth scheduler. This result is of independent interest. We extend these results to feed-forward networks of queues. We also obtain the results when the arrival rate to the queue can be feedback controlled based on the congestion information in the queue (as in ABR service in the ATM networks or in the real time applications controlled by RTCP protocol in the Internet).\",\n \"Title: Approximate theoretical models for TCP connections using different high speed congestion control algorithms in a multihop network.\\nYear: 2013\\n\\nAbstract: We consider a multihop network when the flows may be using TCP Reno, CUBIC or Compound. We study its performance using fluid approximations. We provide theoretical justification for these approximations. Our approximations are simple, yet can be used to obtain throughput and average window size for each TCP connection with good accuracy. We compare results obtained using fluid approximations with discrete Markov chain models in [1] and [2] and with ns2 simulations. The fluid approximation models can be seen to trade-off accuracy for simplicity.\",\n \"Title: Asymptotics for transient and stationary probabilities for finite and infinite buffer discrete time queues\\nYear: 1997\\n\\nAbstract: Consider a discrete time queue with i.i.d. arrivals (see the generalisation below) and a single server with a buffer length m. Let {T}_{m} be the first time an overflow occurs. We obtain asymptotic rate of growth of moments and distributions of {T}_{m} as m \\\\to \\\\infty. We also show that under general conditions, the overflow epochs converge to a compound Poisson process. Furthermore, we show that the results for the overflow epochs are qualitatively as well as quantitatively different from the excursion process of an infinite buffer queue studied in continuous time in the literature. Asymptotic results for several other characteristics of the loss process are also studied, e.g., exponential decay of the probability of no loss (for a fixed buffer length) in time [0, n], as n \\\\to \\\\infty, total number of packets lost in [0, n], maximum run of loss states in [0, n]. We also study tails of stationary distributions. All results extend to the multiserver case and most to a Markov modulated arrival process.\",\n \"Title: Capacity of Gaussian Channels With Energy Harvesting and Processing Cost\\nYear: 2014\\n\\nAbstract: Energy harvesting sensor nodes are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting green communication. In this paper, we focus on communicating reliably over an additive white Gaussian noise channel using such an energy harvesting sensor node. An important part of this paper involves appropriate modeling of energy harvesting, as done via various practical architectures. Our main result is the characterization of the Shannon capacity of the communication system. The key technical challenge involves dealing with the dynamic (and stochastic) nature of the (quadratic) cost of the input to the channel. As a corollary, we find close connections between the capacity achieving energy management policies and the queueing theoretic throughput optimal policies.\",\n \"Title: Analytical Model for Congestion Control and Throughput with TCP CUBIC Connections.\\nYear: 2011\\n\\nAbstract: We develop a Markov model for a TCP CUBIC connection. Next we use it to obtain approximate expressions for throughput when there may be queuing in the network. Finally we provide the throughputs different TCP CUBIC and TCP NewReno connections obtain while sharing a channel when they may have different round trip delays and packet loss probabilities.\",\n \"Title: Error Exponent Analysis of Energy-Based Bayesian Spectrum Sensing under Fading Channels.\\nYear: 2011\\n\\nAbstract: This paper analyzes the error exponents in Bayesian decentralized spectrum sensing, i.e., the detection of occupancy of the primary spectrum by a cognitive radio, with probability of error as the performance metric. At the individual sensors, the error exponents of a Central Limit Theorem (CLT) based detection scheme are analyzed. At the fusion center, a K-out-of-N rule is employed to arrive at the overall decision. It is shown that, in the presence of fading, for a fixed number of sensors, the error exponents with respect to the number of observations at both the individual sensors as well as at the fusion center are zero. This motivates the development of the error exponent with a certain probability as a novel metric that can be used to compare different detection schemes in the presence of fading. The metric is useful, for example, in answering the question of whether to sense for a pilot tone in a narrow band (and suffer Rayleigh fading) or to sense the entire wide-band signal (and suffer log-normal shadowing), in terms of the error exponent performance. The error exponents with a certain probability at both the individual sensors and at the fusion center are derived, with both Rayleigh as well as log-normal shadow fading. Numerical results are used to illustrate and provide a visual feel for the theoretical expressions obtained.\",\n \"Title: Capacity of Gaussian MAC Powered by Energy Harvesters without Storage Buffer\\nYear: 2012\\n\\nAbstract: We consider a Gaussian multiple access channel (GMAC) where the users are sensor nodes powered by energy harvesters. The energy harvester has no buffer to store the harvested energy and hence the energy need to be expended immediately. We assume that the decoder has perfect knowledge of the energy harvesting process. We characterize the capacity region of such a GMAC. We also provide the capacity region when one of the users has infinite buffer to store the energy harvested. Next we find the achievable rates when the energy harvesting information is not available at the decoder.\",\n \"Title: Amplify and forward for correlated data gathering over hierarchical sensor networks\\nYear: 2009\\n\\nAbstract: We address the problem of estimating a random field via a wireless sensor network. We use a Multiple Access Channel (MAC) as the basic building block for such a network. For Gaussian sources over Gaussian MACs, we show that Amplify and Forward scheme (AF) performs well in such sensor network scenarios where the battery power is at a premium. We then extend this result to the hierarchical network scenario and show that it can perform favourably to the Slepian-Wolf based source coding and independent channel coding scheme. Since AF is simple and scalable, a good performance makes it an attractive scheme.\",\n \"Title: A unified approach for analyzing persistent, non-persistent and ON-OFF TCP sessions in the internet\\nYear: 2006\\n\\nAbstract: Most of the studies on TCP assume a fixed number of persistent TCP connections. A few of the recent studies look at non-persistent TCP connections but with many limiting assumptions. We look at a bottleneck router which has real time UDP traffic, TCP ON-OFF traffic and a stochastic flow of non-persistent TCP connections going through it. Our analysis is able to handle a large number (100s) of TCP connections and still provides the mean file download times of each of these connections when all of them have different packet sizes, round trip times and max window size. Using this approach we are able to model almost all the different traffic types that exist in the Internet today. We also study systems employing RED control, which is recommeded to be used in the Internet. We demostrate the effectiveness of RED for congestion control in realistic Internet scenarios both theoretically and via simulations.\",\n \"Title: Some limit theorems for regenerative queues\\nYear: 1998\\n\\nAbstract: We consider a single server queue with the interarrival times and the service times forming a regenerative sequence. This traffic class includes the standard models: \\\\mathit{iid}, periodic, Markov modulated (e.g., BMAP model of Lucantoni [18]) and their superpositions. This class also includes the recently proposed traffic models in high speed networks, exhibiting long range dependence. Under minimal conditions we obtain the rates of convergence to stationary distributions, finiteness of stationary moments, various functional limit theorems and the continuity of stationary distributions and moments. We use the continuity results to obtain approximations for stationary distributions and moments of an MMPP/GI/1 queue where the modulating chain has a countable state space. We extend all our results to feed-forward networks where the external arrivals to each queue can be regenerative. In the end we show that the output process of a leaky bucket is regenerative if the input process is and hence our results extend to a queue with arrivals controlled by a leaky bucket.\",\n \"Title: Achieving Shannon Capacity in a Wiretap Channel via Previous Messages.\\nYear: 2014\\n\\nAbstract: In this paper we consider a wiretap channel with a secret key buffer. We use the coding scheme of [1] to enhance the secrecy rate to the capacity of the main channel, while storing each securely transmitted message in the secret key buffer. We use the oldest secret bits from the buffer to be used as a secret key to transmit a message in a slot and then remove those bits. With this scheme we are able to prove stronger results than those in [1]. i.e., not only the message which is being transmitted currently, but all the messages transmitted in last $N_1$ slots are secure with respect to all the information that the eavesdropper possesses, where $N_1$ can be chosen arbitrarily large.\",\n \"Title: Information capacity of energy harvesting sensor nodes\\nYear: 2011\\n\\nAbstract: Sensor nodes with energy harvesting sources are gaining popularity due to their ability to improve the network life time and are becoming a preferred choice supporting `green communication'. We study such a sensor node with an energy harvesting source and compare various architectures by which the harvested energy is used. We find its Shannon capacity when it is transmitting its observations over an AWGN channel and show that the capacity achieving energy management policies are related to the throughput optimal policies. We also obtain the capacity when energy conserving sleep-wake modes are supported and an achievable rate for the system with inefficiencies in energy storage.\",\n \"Title: Queues with Service Rate Controlled by a Delayed Feedback\\nYear: 2001\\n\\nAbstract: We consider a single queue with a Markov modulated Poisson arrival process. Its service rate is controlled by a scheduler. The scheduler receives the workload information from the queue after a delay. This queue models the buffer in an earth station in a satellite network where the scheduler resides in the satellite. We obtain the conditions for stability, rates of convergence to the stationary distribution and the finiteness of the stationary moments. Next we extend these results to the system where the scheduler schedules the service rate among several competing queues based on delayed information about the workloads in the different queues.\",\n \"Title: Algorithms for routing and centralized scheduling to provide QoS in IEEE 802.16 mesh networks\\nYear: 2005\\n\\nAbstract: We consider the problem of routing and centralized scheduling for IEEE 802.16 mesh networks. We first fix the routing, which reduces the network to a tree. We then present scheduling algorithms which provide per flow QoS (Quality of Service) guarantees to real and interactive data applications while utilizing the network resources efficiently. Our algorithms are also scalable: they do not require per flow processing and queueing and the computational requirements are minimal. We also discuss admission control policies which ensure that sufficient resources are available. We have verified our algorithms via extensive simulations.\",\n \"Title: Optimal MSE Solution for a Decision Feedback Equalizer.\\nYear: 2012\\n\\nAbstract: Due to the inherent feedback in a decision feedback equalizer (DFE) the minimum mean square error (MMSE) or Wiener solution is not known exactly. The main difficulty in such analysis is due to the propagation of the decision errors, which occur because of the feedback. Thus in literature, these errors are neglected while designing and/or analyzing the DFEs. Then a closed form expression is obtained for Wiener solution and we refer this as ideal DFE (IDFE). DFE has also been designed using an iterative and computationally efficient alternative called least mean square (LMS) algorithm. However, again due to the feedback involved, the analysis of an LMS-DFE is not known so far. In this paper we theoretically analyze a DFE taking into account the decision errors. We study its performance at steady state. We then study an LMS-DFE and show the proximity of LMS-DFE attractors to that of the optimal DFE Wiener filter (obtained after considering the decision errors) at high signal to noise ratios (SNR). Further, via simulations we demonstrate that, even at moderate SNRs, an LMS-DFE is close to the MSE optimal DFE. Finally, we compare the LMS DFE attractors with IDFE via simulations. We show that an LMS equalizer outperforms the IDFE. In fact, the performance improvement is very significant even at high SNRs (up to 33%), where an IDFE is believed to be closer to the optimal one. Towards the end, we briefly discuss the tracking properties of the LMS-DFE.\",\n \"Title: AWGN Channel Capacity of Energy Harvesting Transmitters with a Finite Energy Buffer.\\nYear: 2013\\n\\nAbstract: We consider an AWGN channel with a transmitter powered by an energy harvesting source. The node is equipped with a finite energy buffer. Such a system can be modelled as a channel with side information (about energy in the energy buffer) causally known at the transmitter. The receiver may or may not have the side information. We prove that Markov energy management policies are sufficient to achieve the capacity of the system and provide a single letter characterization for the capacity. The computation of the capacity is expensive. Therefore, we discuss an achievable scheme that is easy to compute. This achievable rate converges to the infinite buffer capacity as the buffer length increases.\",\n \"Title: Open queueing networks in discrete time-some limit theorems\\nYear: 1993\\n\\nAbstract: A finite number of nodes, each with a single server and infinite buffers, is considered in discrete time. The service may be FIFO and the service times are constant. The external arrivals and the routing decision variables form a general stationary sequence. Stability of the system is proved under these assumptions. Extension to multiple servers at a node and general stationary distributions holds. If the external input is i.i.d. and the routing is Markovian then stochastic ordering, continuity of stationary distributions, rates of convergence, a functional CLT and a functional LIL and various other limit theorems for the queue length process are also proved. Generalizations to multiple servers at nodes, customers with priority, multiple customer classes, general service length and Markov modulated external arrival cases are discussed.\",\n \"Title: Convergence And Performance Analysis Of Godard Family Of Blind Equalization Algorithms\\nYear: 2003\\n\\nAbstract: We obtain the convergence of the Godard family (including SATO and CM algorithms) In a unified way. Our assumptions are quite realistic: the channel input can be asymptotically stationary and ergodic, the channel impulse response is finite and can be stationary, ergodic (this models fading channels) and the equalizer length is finite. The noise is i.i.d. The channel Input can be discrete or continuous. Our approach allows us to approximate the whole trajectory of the equalizer coefficients. This provides estimates of the rate of convergence an the system performance (symbol error rate) can be evaluated under transience and steady state.\",\n \"Title: A Joint Uplink/Downlink Opportunistic Scheduling Scheme for Infrastructure WLANs.\\nYear: 2013\\n\\nAbstract: We propose a combined uplink/downlink opportunistic scheduling algorithm for infrastructure WLANs. In the presence of both uplink and downlink flows, an infrastructure WLAN suffers from the uplink/downlink unfairness problem which severely decreases the throughput of the access point (AP). We resolve the unfairness by maintaining a separate queue and a backoff timer for each associated mobile station (STA) at the AP. We also increase the system throughput by making the backoff time a function of the channel gains. This reduces the collision probability also. We theoretically analyze the performance of the system under symmetric statistics for all users and validate the analysis by extensive simulations. Simulation results show increase in system throughput by over 40% compared to the 802.11 MAC.\",\n \"Title: Analytical models for capacity estimation of IEEE 802.11 WLANs using DCF for internet applications\\nYear: 2009\\n\\nAbstract: We provide analytical models for capacity evaluation of an infrastructure IEEE 802.11 based network carrying TCP controlled file downloads or full-duplex packet telephone calls. In each case the analytical models utilize the attempt probabilities from a well known fixed-point based saturation analysis. For TCP controlled file downloads, following Bruno et al. (In Networking '04, LNCS 2042, pp.驴626---637), we model the number of wireless stations (STAs) with ACKs as a Markov renewal process embedded at packet success instants. In our work, analysis of the evolution between the embedded instants is done by using saturation analysis to provide state dependent attempt probabilities. We show that in spite of its simplicity, our model works well, by comparing various simulated quantities, such as collision probability, with values predicted from our model. Next we consider N constant bit rate VoIP calls terminating at N STAs. We model the number of STAs that have an up-link voice packet as a Markov renewal process embedded at so called channel slot boundaries. Analysis of the evolution over a channel slot is done using saturation analysis as before. We find that again the AP is the bottleneck, and the system can support (in the sense of a bound on the probability of delay exceeding a given value) a number of calls less than that at which the arrival rate into the AP exceeds the average service rate applied to the AP. Finally, we extend the analytical model for VoIP calls to determine the call capacity of an 802.11b WLAN in a situation where VoIP calls originate from two different types of coders. We consider N 1 calls originating from Type 1 codecs and N 2 calls originating from Type 2 codecs. For G711 and G729 voice coders, we show that the analytical model again provides accurate results in comparison with simulations.\",\n \"Title: Spectrum sensing using distributed sequential detection via noisy reporting MAC.\\nYear: 2015\\n\\nAbstract: This paper considers cooperative spectrum sensing algorithms for Cognitive Radios which focus on reducing the number of samples to make a reliable detection. We propose algorithms based on decentralized sequential hypothesis testing in which the Cognitive Radios sequentially collect the observations, make local decisions and send them to the fusion center for further processing to make a final decision on spectrum usage. The reporting channel between the Cognitive Radios and the fusion center is assumed more realistically as a Multiple Access Channel (MAC) with receiver noise. Furthermore the communication for reporting is limited, thereby reducing the communication cost. We start with an algorithm where the fusion center uses an SPRT-like (Sequential Probability Ratio Test) procedure and theoretically analyze its performance. Asymptotically, its performance is close to the optimal centralized test without fusion center noise. We further modify this algorithm to improve its performance at practical operating points. Later we generalize these algorithms to handle uncertainties in SNR and fading.\",\n \"Title: Learning Equilibrium of a Stochastic Game on Gaussian Interference Channels with Incomplete Information.\\nYear: 2015\\n\\nAbstract: We consider a wireless communication system in which $N$ transmitter-receiver pairs want to communicate with each other. Each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgment (ACK), else it sends a negative ACK (NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium (CE). In addition, we use a no regret algorithm to find a coarse correlated equilibrium (CCE) for our power allocation game. We also propose a fully distributed learning algorithm to find a Pareto optimal solution. In general Pareto points do not guarantee fairness among the users, therefore we also propose an algorithm to compute a Nash bargaining solution which is Pareto optimal and provides fairness among users. Finally, under the same game theoretic setup, we study these equilibria and Pareto points when each transmitter sends data at multiple rates rather than at a fixed rate. We compare the sum rate obtained at the CE, CCE, Nash bargaining solution and the Pareto point and also via some other well known recent algorithms.\",\n \"Title: Algorithms for stochastic games on interference channels\\nYear: 2014\\n\\nAbstract: We consider a wireless channel shared by multiple transmitter-receiver pairs. Their transmissions interfere with each other. Each transmitter-receiver pair aims to maximize its long-term average transmission rate subject to an average power constraint. This scenario is modeled as a stochastic game. We then formulate the problem of finding a Nash equilibrium (NE) as an affine variational inequality (VI) problem, and present an algorithm to solve the VI. We provide sufficient conditions for uniqueness of the NE and convergence of the algorithm which are much weaker than the sufficient conditions available in literature. We also provide a distributed algorithm to compute Pareto optimal solutions for the proposed game.\",\n \"Title: Critter: Content-Rich Traffic Trace Repository\\nYear: 2014\\n\\nAbstract: Access to current application and network data is vital to cybersecurity and networking research. Intrusion detection, steganography, traffic camouflaging, traffic classification and modeling all benefit from real-world data. Such data provides training, testing, and evaluation as well as furthers efforts to reach ground truth. Currently available network data--especially data with application-level information--is often outdated and is either private or customized to specific, narrow research needs. The biggest hurdle to obtaining such content-rich data is addressing the huge privacy risks associated with sharing such complex and open-ended data. In this paper we present a data sharing system called Critter-at-Home which addresses these challenges. Critter connects end-users willing to share data with researchers and strikes a balance between privacy risks for a data contributor and utility for a researcher.\",\n \"Title: Spark: Personalized Parkinson Disease Interventions Through Synergy Between A Smartphone And A Smartwatch\\nYear: 2014\\n\\nAbstract: Parkinson disease (PD) is a neurodegenerative disorder afflicting more than 1 million aging Americans, incurring $23 billion in annual medical costs in the U.S. alone. Approximately 90% Parkinson patients undergoing treatment have mobility related problems related to medication which prevent them doing their activities of daily living. Efficient management of PD requires complex medication regimens specifically titrated to individuals' needs. These personalized regimens are difficult to maintain for the patient and difficult to prescribe for a physician in the few minutes available during office visits. Diverging from current form of laboratory-ridden wearable sensor technologies, we have developed SPARK, a framework that leverages a synergistic combination of Smartphone and Smartwatch in monitoring multidimensional symptoms - such as facial tremors, dysfunctional speech, limb dyskinesia, and gait abnormalities. In addition, SPARK allows physicians to conduct effective tele-interventions on PD patients when they are in non-clinical settings (e. g., at home or work). Initial case series that use SPARK framework show promising results of monitoring multidimensional PD symptoms and provide a glimpse of its potential use in real-world, personalized PD interventions.\",\n \"Title: Optimal power allocation policies for low powered wireless communication systems\\nYear: 2014\\n\\nAbstract: We consider optimal average power allocation policies in a wireless channel in the presence of individual delay constraints on the transmitted packets. Power is consumed in transmission of data only. We consider the case when the power used in transmission is a linear function of the data transmitted. The transmission channel may experience multipath fading. We have developed a computationally efficient online algorithm, when there is same hard delay constraint for all packets. Later on, we generalize it to the case when there are multiple real time streams with different hard deadline constraints. Our algorithm uses linear programming and has very low complexity.\",\n \"Title: Low complexity power and scheduling policies for wireless networks to provide quality of service\\nYear: 2014\\n\\nAbstract: We consider optimal power allocation policies for a single server, multiuser system. The power is consumed in transmission of data only. The transmission channel may experience multipath fading. We obtain very efficient, low computational complexity algorithms which minimize power and ensure stability of the data queues. We also obtain policies when the users may have mean delay constraints. If the power required is a linear function of rate then we exploit linearity and obtain linear programs with low complexity.\",\n \"Title: Novel distributed sequential nonparametric tests for spectrum sensing\\nYear: 2014\\n\\nAbstract: We consider the problem of spectrum sensing in cognitive radio networks under model uncertainties, i.e., the distribution under null hypothesis and the alternate hypothesis is not known. We model the presence of the primary signal as a mean change problem. Two simple nonparametric sequential algorithms for testing the mean are proposed. These nonparametric algorithms are applied to a decentralized detection framework. These algorithms show better performance than some of the existing nonparametric tests in literature. The performance of these algorithms is analysed via theory and simulations.\",\n \"Title: A new algorithm for distributed nonparametric sequential detection\\nYear: 2013\\n\\nAbstract: We consider non parametric sequential hypothesis testing problem when the distribution under the null hypothesis is fully known but the alternate hypothesis corresponds to some other unknown distribution with some loose constraints. We propose a simple algorithm to address the problem. This is also generalized to the case when the distribution under the null hypothesis is not fully known. These problems are primarily motivated from wireless sensor networks and spectrum sensing in Cognitive Radios. A decentralized version utilizing spatial diversity is also proposed. Its performance is analysed and asymptotic properties are proved. The simulated and analysed performance of the algorithm are shown to be better than an earlier algorithm addressing the same problem with similar assumptions. We also modify the algorithm for optimizing performance when information about the prior probabilities of occurrence of the two hypotheses are known.\",\n \"Title: QoS provisioning for multiple femtocells via game theory\\nYear: 2014\\n\\nAbstract: We consider a system with multiple Femtocells (FCs) operating in a Macrocell. The transmissions in one Femtocell interfere with its neighboring Femtocells. Each Femtocell has multiple users, each requiring a minimum transmission rate. There is also peak transmit power constraint in each channel to control interference to the BS and the users in the Macrocell. We formulate the problem of channel allocation and power control in each Femtocell as a noncooperative Game. We develop efficient decentralized algorithms to obtain a Nash equilibrium (NE) that satisfies the Quality of Service (QoS) of each user, in an efficient way. We also obtain efficient decentralized algorithms to obtain fair NE when it may not be feasible to satisfy the QoS of all the users in FCs. Finally, we extend our algorithms to the case where there may be voice and data users in the system.\",\n \"Title: Decomposition of field-induced transmembrane potential responses of single cardiac cells\\nYear: 2002\\n\\nAbstract: In this study, we used a multi-site optical mapping system to record field-induced responses of single cells isolated from guinea pig hearts. The cells were stained with voltage sensitive dye di-8-ANEPPS and stimulated with two uniform field (S1-S2) pulses along their longitudinal axes. The first pulse (S1 = 5 ms, <10 V/cm) was applied during rest and elicited an action potential. The second pulse (S2 = 10 ms, 4-50 V/cm) was applied 15 ms after the break of the S1 pulse (during the action potential plateau). The transmembrane potential responses, Vm(F)s, were optically recorded from up to 12 sites along the cell length using a fiber optic based optical mapping system at a resolution of 17 or 25 microm. The field-induced Vm(F)s had a complex spatio-temporal pattern. We show that these responses can be decomposed into simpler components. The first component, termed the differential-mode component (Vmd(F)), is like the response of a passive cell. The second component, termed the common-mode component (Vmc(F)), is identical all along the cell and adds a constant offset to the differential mode response of various sites along the cell length, to produce the total Vm(F) responses of the cell.\",\n \"Title: Algorithms for computing the capacity of Markov channels with side information\\nYear: 2002\\n\\nAbstract: Consider a finite state, irreducible Markov channel {Sk}. At time k the channel output Y k depends only on the channel input Xk and the channel state Sk. Let Uk and Vk be the CSIT (channel state information at transmitter) and the CSIR (CSI at receiver) respectively. In this paper we provide algorithms to compute the capacity of the Markov channel under various assumptions on CSIT and CSIR where the assumption P(S k = s|U1k) = P(Sk|Uk) is not necessarily satisfied. Our algorithms are based on the extension of ideas developed for channels with feedback.\",\n \"Title: Optimal power control for convolutional and turbo codes over fading channels\\nYear: 2002\\n\\nAbstract: We consider the problem of optimal power allocation to a user transmitting on a fading channel. The our Is using some specific, convolutional or turbo code. The cost function to be minimized is the bit error rate. The user needs to satisfy an average power constraint We And that the optimal power policy is code and fading distribution dependent and can be significantly different from the commonly considered policies e.g, water filling and (truncated) channel inversion. The gain In BER can be substantial.\",\n \"Title: Power constrained and delay optimal policies for scheduling transmission over a fading channel\\nYear: 2003\\n\\nAbstract: I. ABSTRACT We consider an optimal power and rate scheduling problem for a single user transmitting to a base station on a fading wireless link with the objective of minimizing the mean delay subject to an average power constraint. The base station acts as a controller which, depending upon the transmitter buffer lengths and the signal power to interference ratio (SIR) on the uplink pilot channel, allocates transmission rate and power to the user. We provide structural results for an average cost optimal stationary policy under a long run average transmitter power constraint. We obtain a closed form expression relating the optimal policy when the SIR is the best, to the optimal policy for any other SIR value. We also obtain lower and upper bounds for the optimal policy.\",\n \"Title: Comparison of training, blind and semi blind equalizers in MIMO fading systems using capacity as measure\\nYear: 2005\\n\\nAbstract: Semiblind/blind equalizers are believed to work unsatisfactorily in fading MIMO channels compared to training based methods, due to slow convergence or high computational complexity. In this paper we revisit this issue. Defining a 'composite' channel for each equalizer, we compare the three algorithms based on the capacity of this channel. We show that in Ricean (with Line of sight, LOS) environment semiblind/blind algorithms outperform training equalizers. But in Rayleigh channels it is better to use training based methods. We also find the optimum training size in training and semiblind methods.\",\n \"Title: Algorithms for routing and centralized scheduling in IEEE 802.16 mesh networks\\nYear: 2006\\n\\nAbstract: IEEE 802.16 standards for Wireless Metropolitan Area Networks (WMANs) include a mesh mode of operation for improving the coverage and throughput of the network. In this paper, we consider the problem of routing and centralized scheduling for such networks. We first fix the routing, which reduces the network to a tree. We then present a finite horizon dynamic programming framework. Using it we obtain various scheduling algorithms depending upon the cost function. Next we consider simpler suboptimal algorithms and compare their performances. I. INTRODUCTION IEEE 802.16 standard (1), also known as WiMax has been specifically designed to provide wireless last-mile broadband access in the Metropolitan Area Network (MAN), delivering performance comparable to traditional cable, DSL or T1 offerings. In order to provide the coverage and data rates envisioned, even on uneven terrain, the use of multihop communication seems desirable. Hence WiMax supports a Mesh mode in which unlike the traditional cellular systems, the nodes can operate without having a direct connection with the base station. In a IEEE 802.16d Mesh network, a system that has a direct connection to backhaul services outside the Mesh network, is termed a Mesh Base Station (MBS). All other systems of a Mesh network are termed Mesh Subscriber Stations (MSS). The IEEE 802.16d standards do not support mobility. The standard specifies a centralized scheduling scheme for mesh networks. Under this scheme, the MSSs notify the MBS their data transfer requirements and the quality of their links to their neighbours. The MBS uses the topology information along with the requirements of each MSS to decide the routing and the scheduling. The MAC scheme used is TDMA and the resource allocation is in terms of time slots within a frame. The standard does not specify an algorithm for scheduling of the slots to different MSSs; neither does it specify any routing algorithm. Scheduling and routing will have significant impact on the performance of the system and will largely decide the end to end quality of service (QoS) to different users. and (12). But in these studies spectral reuse is employed. Thus scheduling in these studies cannot be used in our system.(More recently 802.16 standard also allows channel reuse with the option of minimum hop distance of 1, 3 or 7 for reuse. Taking it 7 will practically make it a system without channel reuse.) Also some of the assumptions made in these studies do not hold in our system. In (12) (p.310), Klimov's algorithm is provided where a single server is shared by various queues. The assumptions required here are also not satisfied in our setup. However we modify this algorithm and then compare with other algorithms we develop. In this paper, we present algorithms for centralized scheduling with the objective of maximizing the network throughput within the framework of the IEEE 802.16 mesh mode. We first fix the routing within the network. We then present a finite horizon dynamic programming framework which optimizes a cost function over a fixed number of time slots. Depending upon the cost function, we obtain good scheduling algorithms which are then compared with each other and also with some of the standard algorithms available in literature. As mentioned above, in this paper we provide routing and scheduling algorithms that optimize the system performance. This has also been the goal of the other studies mentioned above. However one can also look from the user's point of view to obtain algorithms which help provide end-to- end QoS (Quality of Service) to individual connections. We have used the lessons learnt in this study and modified these algorithms to provide QoS to individual real and nonreal time (which use TCP) applications in (11). The organization of the paper is as follows. Section II describes the system model. Section III provides a good rout- ing scheme. Section IV develops the scheduling algorithms and compares them via simulations. Section V concludes the paper.\",\n \"Title: Efficient and fair scheduling of uplink and downlink in IEEE 802.16 OFDMA networks\\nYear: 2006\\n\\nAbstract: We develop new scheduling algorithms for the IEEE 802.16d OFDMA/TDD based broadband wireless access system, in which radio resources of both time and frequency slots are dynamically shared by all users. Our objective is to provide a fair and efficient allocation to all the users to satisfy their quality of service. Keywords : OFDMA, fair scheduling, IEEE 802.16d, resource allocation, QoS.\",\n \"Title: Distributed coding for multiple access communication with side information\\nYear: 2006\\n\\nAbstract: In a typical sensor network scenario a goal is to monitor a spatio-temporal process through a number of inexpensive sensing nodes, the key parameter being the fidelity at which the process has to be estimated at distant locations. We study such a scenario in which multiple encoders transmit their correlated data at finite rates to a distant, common decoder over a discrete time multiple access channel under various side information assumptions. In particular, we derive an achievable rate region for this communication problem\",\n \"Title: Providing QoS to Real and Data Applications in WiMAX Mesh Networks\\nYear: 2008\\n\\nAbstract: We consider the problem of centralized routing and scheduling for IEEE 802.16 mesh networks so as to provide Quality of Service (QoS) to individual real and interactive data applications. We first obtain an optimal and fair routing and scheduling policy for aggregate demands for different source- destination pairs. We then present scheduling algorithms which provide per flow QoS guarantees while utilizing the network resources efficiently. Our algorithms are also scalable: th ey do not require per flow processing and queueing and the computation al requirements are modest. We have verified our algorithms via extensive simulations.\",\n \"Title: Computing TCP Throughput in a UMTS Network\\nYear: 2008\\n\\nAbstract: We compute the throughput obtained by a TCP connection in a UMTS environment. For downloading data at a mobile terminal, the packets of each TCP connection are stored in separate queues at the base station (node B). Also due to fragmentation of the TCP packets into Protocol Data Units (PDU) and link layer retransmissions of PDUs there can be significant delays at the queue of the node B. In such a scenario the existing models of TCP may not be sufficient. Thus, we provide a new approximate TCP model and also obtain new closed-form expressions of mean window size. Using these we obtain the throughput of a TCP connection which matches with simulations quite well. Keywords: UMTS, TCP, throughput computation, mean window size.\",\n \"Title: Energy efficient change detection over a MAC using physical layer fusion\\nYear: 2008\\n\\nAbstract: We propose a simple and energy efficient distributed change detection scheme for sensor networks based on Page's parametric CUSUM algorithm. The sensor observations are IID over time and across the sensors conditioned on the change variable. Each sensor runs CUSUM and transmits only when the CUSUM is above some threshold. The transmissions from the sensors are fused at the physical layer. The channel is modeled as a multiple access channel (MAC) corrupted with IID noise. The fusion center which is the global decision maker, performs another CUSUM to detect the change. We provide the analysis and simulation results for our scheme and compare the performance with an existing scheme which ensures energy efficiency via optimal power selection.\",\n \"Title: Optimal Sleep-Wake Policies for an Energy Harvesting Sensor Node\\nYear: 2009\\n\\nAbstract: We study a sensor node with an energy harvesting source. In any slot, the sensor node is in one of two modes: Wake or Sleep. The generated energy is stored in a buffer. The sensor node senses a random field and generates a packet when it is awake. These packets are stored in a queue and transmitted in the wake mode using the energy available in the energy buffer. We obtain energy management policies which minimize a linear combination of the mean queue length and the mean data loss rate. Then, we obtain two easily implementable suboptimal policies and compare their performance to that of the optimal policy. Next, we extend the Throughput Optimal policy developed in our previous work to sensors with two modes. Via this policy, we can increase the throughput substantially and stabilize the data queue by allowing the node to sleep in some slots and to drop some generated packets. This policy requires minimal statistical knowledge of the system. We also modify this policy to decrease the switching costs.\",\n \"Title: Diversity order vs rate in an AWGN channel\\nYear: 2011\\n\\nAbstract: We study the diversity order vs rate of an additive white Gaussian noise (AWGN) channel in the whole capacity region. We show that for discrete input as well as for continuous input, Gallager's upper bounds on error probability have exponential diversity in low and high rate region but only subexponential in the mid-rate region. For the best available lower bounds and for the practical codes one observes exponential diversity throughout the capacity region. However we also show that performance of practical codes is close to Gallager's upper bounds and the mid-rate subexponential diversity has a bearing on the performance of the practical codes. Finally we show that the upper bounds with Gaussian input provide good approximation throughout the capacity region even for finite constellation.\",\n \"Title: Queuing theoretic and information theoretic capacity of energy harvesting sensor nodes\\nYear: 2011\\n\\nAbstract: Energy harvesting sensor networks provide near perpetual operation and reduce carbon emissions thereby supporting `green communication'. We study such a sensor node powered with an energy harvesting source. We obtain energy management policies that are throughput optimal. We also obtain delay-optimal policies. Next we obtain the Shannon capacity of such a system. Further we combine the information theoretic and queuing theoretic approaches to obtain the Shannon capacity of an energy harvesting sensor node with a data queue. Then we generalize these results to models with fading and energy consumption in activities other than transmission.\",\n \"Title: Joint routing, scheduling and power control in multihop MIMO networks with MAC and broadcast links\\nYear: 2012\\n\\nAbstract: We consider the problem of joint routing, scheduling and power control in a multihop wireless network when the nodes have multiple antennas. We focus on exploiting the multiple degrees-of-freedom available at each transmitter and receiver due to multiple antennas. Specifically we use multiple antennas at each node to form multiple access and broadcast links in the network rather than just point to point links. We show that such a generic transmission model improves the system performance significantly. Since the complexity of the resulting optimization problem is very high, we also develop efficient suboptimal solutions for joint routing, scheduling and power control in this setup.\",\n \"Title: Achievable secrecy sum-rate in a fading MAC-WT with power control and without CSI of eavesdropper\\nYear: 2011\\n\\nAbstract: We consider a two user fading Multiple Access Channel with a wire-tapper (MAC-WT) where the transmitter has the channel state information (CSI) to the intended receiver but not to the eavesdropper (eve). We provide an achievable secrecy sum-rate with optimal power control. We next provide a secrecy sum-rate with optimal power control and cooperative jamming (CJ). We then study an achievable secrecy sum rate by employing an ON/OFF power control scheme which is more easily computable. We also employ CJ over this power control scheme. Results show that CJ boosts the secrecy sum-rate significantly even if we do not know the CSI of the eve's channel. At high SNR, the secrecy sum-rate (with CJ) without CSI of the eve exceeds the secrecy sum-rate (without CJ) with full CSI of the eve.\",\n \"Title: Cooperative robust sequential detection algorithms for Spectrum Sensing in Cognitive Radio\\nYear: 2009\\n\\nAbstract: We consider the problem of Spectrum Sensing in Cogni- tive Radio Networks. In our previous work we have developed Du- alCUSUM, a distributed algorithm for change detection and used it for cooperative spectrum sensing. The algorithm is based on se- quential change detection techniques which optimally use the past observations. But DualCUSUM requires the knowledge of the channel gains for each of the secondary users. In this work we mod- ify DualCUSUM to develop GLR-CUSUM which can work with imprecise estimates of the channel gains. Next we extend the algo- rithm to the case where the receiver noise power is also not known exactly. We show that the SNR wall problem encountered in this scenario is not experienced by our algorithm. We also analyze these algorithms theoretically.\",\n \"Title: Diversity-rate trade-off for fading channels with power control\\nYear: 2012\\n\\nAbstract: We consider a complex, additive, white Gaussian noise channel with flat fading. We study its diversity order vs transmission rate for some known power allocation schemes. The capacity region is divided into three regions. For one power allocation scheme, the diversity order is exponential throughout the capacity region. For selective channel inversion (SCI) scheme, the diversity order is exponential in low and high rate region but polynomial in mid rate region. For fast fading case we also provide a new upper bound on block error probability and a power allocation scheme that minimizes it. The diversity order behaviour of this scheme is same as for SCI but provides lower BER than the other policies.\",\n \"Title: Cyclic Prefix Based Cooperative Sequential Spectrum Sensing Algorithms for OFDM\\nYear: 2010\\n\\nAbstract: This paper considers the problem of spectrum sensing in cognitive radio networks when the primary user is using Orthogonal Frequency Division Multiplexing (OFDM). For this we develop cooperative sequential detection algorithms that use the autocorrelation property of cyclic prefix (CP) used in OFDM systems. We study the effect of timing and frequency offset, IQ-imbalance and uncertainty in noise and transmit power. We also modify the detector to mitigate the effects of these impairments. The performance of the proposed algorithms is studied via simulations. We show that sequential detection can significantly improve the performance over a fixed sample size detector.\",\n \"Title: Previous messages provide the key to achieve shannon capacity in a wiretap channel\\nYear: 2013\\n\\nAbstract: We consider a wiretap channel and use previously transmitted messages to generate a secret key which increases the secrecy capacity. This can be bootstrapped to increase the secrecy capacity to the Shannon capacity without using any feedback or extra channel while retaining the strong secrecy of the wiretap channel.\",\n \"Title: New algorithms for wideband spectrum sensing via compressive sensing\\nYear: 2013\\n\\nAbstract: We consider the problem of spectrum sensing in a Cognitive Radio (CR) system when the primaries can be occupying a few subbands in a wideband spectrum. Since the primary signal dimension is large, Nyquist rate can be very high. Compressive sensing (CS) can be useful in this setup. However a CR system needs to operate at a very low SNR(~ -20dB) where the compressive sensing techniques are usually not successful. Combining them with statistical techniques can be useful. But this has been difficult because the statistics of the parameters obtained from the recovery algorithms (e.g., OMP) are not available. We develop a suboptimal recovery algorithm COR for which the statistics can be easily approximated. This allows us to use Neyman Pearson technique as well as sequential detection techniques with CS. The resulting algorithms provide satisfactory performance at -20 dB SNR. In fact COR's recovery performance is better than OMP itself at low SNR. We also modify the algorithm for the scenario when the channel gains and the noise variance may also not be available.\",\n \"Title: Achieving shannon capacity region as secrecy rate region in a multiple access wiretap channel\\nYear: 2015\\n\\nAbstract: We consider a two user multiple-access channel with an eavesdropper at the receiving end. We use previously transmitted messages as a key in the next slot till we achieve the capacity region of the usual multiple access channel (MAC).\",\n \"Title: A Theoretical Framework for Hierarchical Routing Games\\nYear: 2010\\n\\nAbstract: Most theoretical research on routing games in telecommunication networks has so far dealt with reciprocal congestion effects between routed entities. Yet in networks that support differentiation between flows, the congestion experienced by a packet depends on its priority level. Another differentiation is made by compressing the packets in the low priority flow while leaving the high priority flow intact. In this paper we study such kind of routing scenarios for the case of non-atomic users and we establish conditions for the existence and uniqueness of equilibrium.\",\n \"Title: Spectrum sensing via universal source coding\\nYear: 2012\\n\\nAbstract: We consider nonparametric sequential hypothesis testing when the distribution under null hypothesis is fully known and the alternate hypothesis corresponds to some other unknown distribution. We use easily implementable universal lossless source codes to propose simple algorithms for such a setup. These algorithms are motivated from spectrum sensing application in Cognitive Radios. Universal sequential hypothesis testing using Lempel Ziv codes and Krichevsky-Trofimov estimator with Arithmetic Encoder are considered and compared for different distributions. Cooperative spectrum sensing with multiple Cognitive Radios using universal codes is also considered.\",\n \"Title: Nonparametric distributed sequential detection via universal source coding\\nYear: 2013\\n\\nAbstract: We consider nonparametric or universal sequential hypothesis testing when the distribution under the null hypothesis is fully known but the alternate hypothesis corresponds to some other unknown distribution. These algorithms are primarily motivated from spectrum sensing in Cognitive Radios and intruder detection in wireless sensor networks. We use easily implementable universal lossless source codes to propose simple algorithms for such a setup. The algorithms are first proposed for discrete alphabet. Their performance and asymptotic properties are studied theoretically. Later these are extended to continuous alphabets. Their performance with two well known universal source codes, Lempel-Ziv code and KT-estimator with Arithmetic Encoder are compared. These algorithms are also compared with the tests using various other nonparametric estimators. Finally a decentralized version utilizing spatial diversity is also proposed and analysed.\",\n \"Title: Atomic hierarchical routing games in communication networks\\nYear: 2010\\n\\nAbstract: Theoretical studies on routing games in networks have so far dealt with reciprocal congestion effects between routing entities. But, with the advent of technologies like Cognitive Radio, we have networks which support differentiation of flows. In a two priority level model a user can be high priority or low priority and there is a cost for such a classification. The point of departure of this model from the traditional routing scenarios is the absence of reciprocity in the congestion effects: The low priority flow faces congestion from both high priority as well as low priority flow while the high priority flow is immune to the congestion effects from the low priority flow. This hierarchy is naturally present in contexts where there are primary (licensed) users and secondary (unlicensed) users who can sense their environment because there are equipped with a cognitive radio. We study such kind of routing scenarios for the cases of atomic users. We establish the existence and the uniqueness of Nash equilibrium and further we show the existence of a potential function for linear congestion costs and a certain priority classification pricing scheme. Natural applications of this model to Cognitive Radio are also pointed out.\",\n \"Title: Energy efficient low complexity joint scheduling and routing for wireless networks\\nYear: 2015\\n\\nAbstract: We consider a multihop wireless network with multiple users. The channels may experience fading. The power is consumed only during transmission and is a general monotonically increasing function of rate. We provide low complexity algorithms for joint routing, scheduling and power control which ensure stability of the queues, certain minimum rates and/or upper bound on the end-to-end, mean delays.\",\n \"Title: Distributed learning of equilibria for a stochastic game on interference channels\\nYear: 2015\\n\\nAbstract: We consider a wireless communication system in which N transmitter-receiver pairs want to communicate with each other. Each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgement (ACK), else it sends a negative ACK (NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium (CE). We also propose a fully distributed learning algorithm to find a Pareto optimal solution, and we compare the utilities of each user at the CE and the Pareto point and also with some other well known recent algorithms.\",\n \"Title: Stability and performance analysis of rate-based feedback flow controlled ATM networks\\nYear: 1998\\n\\nAbstract: Motivated by ABR class of service in ATM networks, we study a continuous time queueing system with a feedback control of the arrival rate of some of the sources. The feedback about the queue length or the total workload is provided at regular intervals (variations on it, especially the traffic management specification TM 4.0, are also considered). The propagation delays can be nonnegligible. For a general class of feedback algorithms, we obtain the stability of the system in the presence of one or more bottleneck nodes in the virtual circuit. Our system is general enough that it can be useful to study feedback control in other network protocols. We also obtain rates of convergence to the stationary distributions and finiteness of moments. For the single botterneck case, we provide algorithms to compute the stationary distributions and the moments of the sojourn times in different sets of states. We also show analytically (by showing continuity of stationary distributions and moments) that for small propagation delays, we can provide feedback algorithms which have higher mean throughput, lower probability of overflow and lower delay jitter than any open loop policy. Finally these results are supplemented by some computational results.\",\n \"Title: Analysis of Multiple Flows using Different High Speed TCP protocols on a General Network.\\nYear: 2016\\n\\nAbstract: We develop analytical tools for performance analysis of multiple TCP flows (which could be using TCP CUBIC, TCP Compound, TCP New Reno) passing through a multi-hop network. We first compute average window size for a single TCP connection (using CUBIC or Compound TCP) under random losses. We then consider two techniques to compute steady state throughput for different TCP flows in a multi-hop network. In the first technique, we approximate the queues as M/G/1 queues. In the second technique, we use an optimization program whose solution approximates the steady state throughput of the different flows. Our results match well with ns2 simulations.\",\n \"Title: Achieving Shannon Capacity in a Fading Wiretap Channel.\\nYear: 2015\\n\\nAbstract: Reliable communication imposes an upper limit on the achievable rate, namely the Shannon capacity. Wyneru0027s wiretap coding, which ensures a security constraint also in addition to reliability, results in decrease of the achievable rate. To mitigate the loss in the secrecy rate, we propose a coding scheme paper where we use sufficiently old messages as key and for this scheme prove that multiple messages are secure with respect to (w.r.t.) all the information possessed by the eavesdropper. We also show that we can achieve security in the strong sense. Next we consider a fading wiretap channel with full channel state information of the eavesdropperu0027s channel and use our coding/decoding scheme to achieve secrecy capacity close to the Shannon capacity of the main channel (in the ergodic sense). Finally we also consider the case where the transmitter does not have the instantaneous information of the channel state of the eavesdropper, but only its distribution.\",\n \"Title: Distributed Algorithms for Complete and Partial Information Games on Interference Channels.\\nYear: 2016\\n\\nAbstract: We consider a Gaussian interference channel with independent direct and cross link channel gains, each of which is independent and identically distributed across time. Each transmitter-receiver user pair aims to maximize its long-term average transmission rate subject to an average power constraint. We formulate a stochastic game for this system in three different scenarios. First, we assume that each user knows all direct and cross link channel gains. Later, we assume that each user knows channel gains of only the links that are incident on its receiver. Lastly, we assume that each user knows only its own direct link channel gain. In all cases, we formulate the problem of finding a Nash equilibrium (NE) as a variational inequality (VI) problem. We present a novel heuristic for solving a VI. We use this heuristic to solve for a NE of power allocation games with partial information. We also present a lower bound on the utility for each user at any NE in the case of the games with partial information. We obtain this lower bound using a water-filling like power allocation that requires only knowledge of the distribution of a useru0027s own channel gains and average power constraints of all the users. We also provide a distributed algorithm to compute Pareto optimal solutions for the proposed games. Finally, we use Bayesian learning to obtain an algorithm that converges to an $epsilon$-Nash equilibrium for the incomplete information game with direct link channel gain knowledge only without requiring the knowledge of the power policies of the other users.\",\n \"Title: Error exponent analysis of energy-based Bayesian decentralized spectrum sensing under fading\\nYear: 2015\\n\\nAbstract: This paper considers decentralized spectrum sensing, i.e., detection of occupancy of the primary users' spectrum by a set of Cognitive Radio (CR) nodes, under a Bayesian set-up. The nodes use energy detection to make their individual decisions, which are combined at a Fusion Center (FC) using the K -out-of- N fusion rule. The channel from the primary transmitter to the CR nodes is assumed to undergo fading, while that from the nodes to the FC is assumed to be error-free. In this scenario, a novel concept termed as the Error Exponent with a Confidence Level (EECL) is introduced to evaluate and compare the performance of different detection schemes. Expressions for the EECL under general fading conditions are derived. As a special case, it is shown that the conventional error exponent both at individual sensors, and at the FC is zero. Further, closed-form lower bounds on the EECL are derived under Rayleigh fading and lognormal shadowing. As an example application, it answers the question of whether to use pilot-signal based narrowband sensing, where the signal undergoes Rayleigh fading, or to sense over the entire bandwidth of a wideband signal, where the signal undergoes lognormal shadowing. Theoretical results are validated using Monte Carlo simulations.\",\n \"Title: Information rates over an AWGN channel with an energy harvesting transmitter having a finite energy buffer\\nYear: 2015\\n\\nAbstract: We consider an AWGN channel with a transmitter powered by an energy harvesting source. The node is equipped with a finite energy buffer. Such a system can be modelled as a channel with side information (about energy in the energy buffer) causally known at the transmitter. The receiver is assumed to have no side information. First, we provide an achievable scheme that approximates the system capacity at low buffer lengths. Next we consider a scheme viz. the truncated Gaussian signalling that provides excellent approximation to system capacity at large buffer lengths. These achievable rates are easy to compute and converge to the infinite buffer capacity as the buffer length increases. The achievable schemes we discuss belong to a general class of policies called Markov energy management policies. Markov energy management policies together with Shannon strategies provide good lower bounds to the system capacity.\",\n \"Title: Power allocation games on interference channels with complete and partial information\\nYear: 2015\\n\\nAbstract: We consider a Gaussian interference channel with independent direct and cross link channel gains, each of which is independent and identically distributed across time. Each transmitter-receiver user pair aims to maximize its long-term average transmission rate subject to an average power constraint. We formulate a stochastic game for this system in three different scenarios. First, we assume that each user knows all direct and cross link channel gains. Later, we assume that each user knows channel gains of only the links that are incident on its receiver. Lastly, we assume that each user knows only its own direct link channel gain. In all cases, we formulate the problem of finding the Nash equilibrium as a variational inequality (VI) problem and present a novel heuristic for solving the VI. We also present a lower bound on the utility for each user at any Nash equilibrium in the case of the games with partial information. We obtain this lower bound using a water-filling like power allocation that requires only knowledge of the distribution of a user's own channel gains and average power constraints of all users.\",\n \"Title: Throughput of TCP over Cognitive Radio Channels.\\nYear: 2016\\n\\nAbstract: We study TCP performance over ON-OFF channels, i.e., channels which are busy/unavailable for transmissions intermittently. The data may also be subject to random errors. Such situations arise in cognitive radio networks when secondary users opportunistically use the channel when the licensed user is not using it. We use a Markov model to evaluate the TCP throughput and probability of retransmission timeout when the ON-OFF periods are exponentially distributed and then extend it to phase-type ON and phase-type OFF periods. We then generalize the Markovian model to more general ON-OFF duration distributions and also to multiple TCP connections.\",\n \"Title: Performance Based Evaluation of Various Machine Learning Classification Techniques for Chronic Kidney Disease Diagnosis.\\nYear: 2016\\n\\nAbstract: Areas where Artificial Intelligence (AI) u0026 related fields are finding their applications are increasing day by day, moving from core areas of computer science they are finding their applications in various other domains.In recent times Machine Learning i.e. a sub-domain of AI has been widely used in order to assist medical experts and doctors in the prediction, diagnosis and prognosis of various diseases and other medical disorders. In this manuscript the authors applied various machine learning algorithms to a problem in the domain of medical diagnosis and analyzed their efficiency in predicting the results. The problem selected for the study is the diagnosis of the Chronic Kidney Disease.The dataset used for the study consists of 400 instances and 24 attributes. The authors evaluated 12 classification techniques by applying them to the Chronic Kidney Disease data. In order to calculate efficiency, results of the prediction by candidate methods were compared with the actual medical results of the subject.The various metrics used for performance evaluation are predictive accuracy, precision, sensitivity and specificity. The results indicate that decision-tree performed best with nearly the accuracy of 98.6%, sensitivity of 0.9720, precision of 1 and specificity of 1.\",\n \"Title: Resource Allocation in a MAC with and without security via Game Theoretic Learning.\\nYear: 2017\\n\\nAbstract: In this paper, we study a K-user fading multiple access channel (F-MAC), with and without an eavesdropper (Eve). In the system without Eve, we assume that each user knows only its own channel gain and is completely ignorant about the other users’ channel state. The legitimate receiver sends a short acknowledgement message Acknowledge (ACK) if the message is correctly decoded and a No Acknowledge (NACK) if the message is not correctly decoded. Under these assumptions, we use game theoretic learning setup to make transmitters learn about the power allocation under each state. We use multiplicative weight no-regret algorithm to achieve an ε-coarse correlated equilibrium. We also consider the case where a user can receive other users’ ACK/NACK messages. Now, we can maximize a weighted sum utility and achieve Pareto optimal points. We also obtain Nash bargaining solutions, which are Pareto points that are fairer to the transmitting users. Fairness among users is quantified using Jain’s index.\",\n \"Title: On Strategic Multi-Antenna Jamming in Centralized Detection Networks.\\nYear: 2017\\n\\nAbstract: In this letter, we model a complete-information zero-sum game between a centralized detection network with a multiple access channel between the sensors and the fusion center (FC), and a jammer with multiple transmitting antennas. We choose error probability at the FC as the performance metric, and investigate pure strategy equilibria for this game, and show that the jammer has no impact on the FC...\",\n \"Title: A Distributed Algorithm for Quality-of-Service Provisioning in Multihop Networks.\\nYear: 2017\\n\\nAbstract: We present a distributed algorithm for joint power control, routing and scheduling in multihop wireless networks. The algorithm also provides for Quality of Service (QoS) guarantees, namely, end-to-end mean delay guarantees and hard deadline guarantees, for different users. It is easily implementable and works by giving local dynamic priority to flows requiring QoS, the priority being a function of the queue length at the nodes. We provide theoretical bounds for the stability properties of the algorithm. We also compare the performance of the algorithm with other existing algorithms by means of extensive simulations, and demonstrate its efficacy in providing QoS on demand.\",\n \"Title: Jointly broadcasting data and power with quality of service guarantees\\nYear: 2017\\n\\nAbstract: In this work, we consider a scenario wherein an energy harvesting wireless radio equipment sends information to multiple receivers alongside powering them. In addition to harvesting the incoming radio frequency (RF) energy, the receivers also harvest energy from its environment (e.g., solar energy). This communication framework is captured by a fading Gaussian Broadcast Channel (GBC) with energy harvesting transmitter and receivers. In order to ensure some quality of service (QoS) in data reception among the receivers, we impose a minimumrate requirement on data transmission. For the setting in place, we characterize the fundamental limits in jointly transmitting information and power subject to a QoS guarantee, for three cardinal receiver structures namely, ideal, time-switching and power-splitting. We show that a time-switching receiver can switch between information reception mode and energy harvesting mode, without the transmitter's knowledge of the same and without any extra rate loss. We also prove that, for the same amount of power transferred, on average, a power-splitting receiver supports higher data rates compared to a time-switching receiver.\",\n \"Title: Information and Power Transfer by Energy Harvesting Transmitters over a Fading Multiple Access Channel with Minimum Rate Constraints.\\nYear: 2016\\n\\nAbstract: We consider the problem of Simultaneous Wireless Information and Power Transfer (SWIPT) over a fading multiple access channel with additive Gaussian noise. The transmitters as well as the receiver harvest energy from ambient sources. We assume that the transmitters have two classes of data to send, viz. delay sensitive and delay tolerant data. Each transmitter sends the delay sensitive data at a certain minimum rate irrespective of the channel conditions (fading states). In addition, if the channel conditions are good, the delay tolerant data is sent. {Along with data, the transmitters also transfer power to aid the receiver in meeting its energy requirements.} In this setting, we characterize the textit{minimum-rate capacity region} which provides the fundamental limit of transferring information and power simultaneously with minimum rate guarantees. Owing to the limitations of current technology, these limits might not be achievable in practice. Among the practical receiver structures proposed for SWIPT in literature, two popular architectures are the textit{time switching} and textit{power splitting} receivers. For each of these architectures, we derive the minimum-rate capacity regions. We show that power splitting receivers although more complex, provide a larger capacity region.\",\n \"Title: Finite Blocklength Analysis Of Energy Harvesting Channels\\nYear: 2016\\n\\nAbstract: We consider additive white Gaussian noise channels and discrete memoryless channels where the transmitter harvests energy from the environment. These can model wireless sensor networks as well as Internet of Things. By providing a unifying framework that works for any energy harvesting channel, we study these channels assuming an infinite energy buffer and provide the corresponding achievability and converse bounds on the channel capacity in the finite blocklength regime. We additionally provide moderate deviation asymptotic bounds.\",\n \"Title: An asymptotic approximation for TCP compound.\\nYear: 2017\\n\\nAbstract: In this paper, we derive an approximation for throughput of TCP Compound connections under random losses. Throughput expressions for TCP Compound under a deterministic loss model exist in the literature. These are obtained assuming that the window sizes are continuous, i.e., a fluid behavior is assumed. We validate this model theoretically. We show that under the deterministic loss model, the TCP window evolution for TCP Compound is asymptotically periodic and is independent of the initial window size. We then consider the case when packets are lost randomly and independently of each other. We discuss Markov chain models to analyze performance of TCP in this scenario. We use insights from the deterministic loss model to get an appropriate scaling for the window size process and show that these scaled processes, indexed by p, the packet error rate, converge to a limit Markov chain process as p goes to 0. We show the existence and uniqueness of the stationary distribution for this limit process. Using the stationary distribution for the limit process, we obtain approximations for throughput, under random losses, for TCP Compound when packet error rates are small. We compare our results with ns2 simulations which show a good match and a better approximation than the fluid model at low p.\",\n \"Title: An Achievable Rate for an Optical Channel with Finite Memory.\\nYear: 2017\\n\\nAbstract: A fiber optic channel is modeled in a variety of ways; from the simple additive white complex Gaussian noise model, to models that incorporate memory in the channel. Because of Kerr nonlinearity, a simple model is not a good approximation to an optical fiber. Hence we study a fiber optic channel with finite memory and provide an achievable bound on channel capacity that improves upon a previously known bound.\",\n \"Title: Finite Blocklength Rates over a Fading Channel with CSIT and CSIR\\nYear: 2018\\n\\nAbstract: In this work, we obtain lower and upper bounds on the maximal {transmission} rate at a given codeword length $n$, average probability of error $\\\\epsilon$ and power constraint $\\\\bar{P}$, over a finite valued, block fading additive white Gaussian noise (AWGN) channel with channel state information (CSI) at the transmitter {and the receiver}. {These bounds characterize} deviation of the finite blocklength coding rates from the channel capacity which is in turn achieved by the \\\\textit{water filling} power allocation across time. {The bounds obtained also} characterize the rate enhancement possible due to the {CSI} at the transmitter in the finite blocklength regime. The results are further elucidated via numerical examples.\",\n \"Title: Algorithms for Nash and Pareto Equilibria for Resource Allocation in Multiple Femtocells.\\nYear: 2017\\n\\nAbstract: We consider a cellular system with multiple Femtocells operating in a Macrocell. They are sharing a set of communication channels. Each Femtocell has multiple users requiring certain minimum rate guarantees. Each channel has a peak power constraint to limit interference to the Macro Base Station (BS). We formulate the problem of channel allocation and power control at the Femtocells as a noncooperative Game. We develop decentralized algorithms to obtain a Coarse Correlated equilibrium that satisfies the QoS of each user. If the QoS of all the users cannot be satisfied, then we obtain a fair equilibrium. Finally we also provide a decentralized algorithm to reach a Pareto and a Nash Bargaining solution which has a much lower complexity than the algorithm to compute the NE.\",\n \"Title: A Distributed Scheduling Algorithm to Provide Quality-of-Service in Multihop Wireless Networks.\\nYear: 2017\\n\\nAbstract: Control of multihop Wireless networks in a distributed manner while providing end-to-end delay requirements for different flows, is a challenging problem. Using the notions of Draining Time and Discrete Review from the theory of fluid limits of queues, an algorithm that meets delay requirements to various flows in a network is constructed. The algorithm involves an optimization which is implemented in a cyclic distributed manner across nodes by using the technique of iterative gradient ascent, with minimal information exchange between nodes. The algorithm uses time varying weights to give priority to flows. The performance of the algorithm is studied in a network with interference modelled by independent sets.\",\n \"Title: Learning Equilibria For Power Allocation Games In Cognitive Radio Networks With A Jammer\\nYear: 2016\\n\\nAbstract: In this paper, competitive interactions between a secondary transmitter-receiver pair and a jammer are investigated in a distributed manner over N orthogonal frequency bands, each of which is licensed to a primary user (PU). There is an interference restriction at the secondary receiver (SR) and power budget constraints at the secondary transmitter (ST) and the jammer. In addition, the ST (jammer) does not know the channels' gains of the jammer (ST). After sensing each of the frequency bands, the ST and the jammer decide how to transmit information and how to block these transmissions respectively. In this respect, both the ST and the jammer incur a communication cost and the SR sends an acknowledgment (ACK) if it decodes the information correctly. Otherwise, it sends a negative ACK (NACK). The strategic and distributed power allocation between the ST and the jammer is modeled as a stochastic game in which we employ a multiplicative weight no-regret learning mechanism to obtain an equilibrium point.\",\n \"Title: Detection diversity of spatio-temporal data using Pitman's efficiency for low SNR regimes\\nYear: 2016\\n\\nAbstract: In this work, we use Pitman's efficiency to characterize the diversity of a spatio-temporal distributed detection system. Pitman's efficiency directly measures the detection ability of the data at low signal to noise ratios (SNRs). We study how the statistics of spatio-temporal distributed data affect the diversity of the system. We derive the diversity measure for the optimal likelihood ratio test (LRT) statistic for slow fading channels. Moreover, we capture the heterogeneity of channel gains and channel noise variances in our diversity expressions. Then, we compare our diversity measure with another one that was also proposed for low SNRs.\",\n \"Title: Neuro-fuzzy approach in business applications: a decade survey.\\nYear: 2017\\n\\nAbstract: This paper presents a survey of the application-based research on neuro-fuzzy systems (NFS) in business on account of the research articles published in various reputed international journals and conferences during the last decade (2005-2014). The application of the NFS in different business domains has diversified enormously during this period and NFS has emerged as a dominant technique for addressing various research problems in various business domains. On the basis of an in-depth review of these research articles, we have identified finance, marketing, distribution, business planning, information systems, production and operations as the main business application domains of NFS during this period. The impact of NFS in different business domains and the trends in this application-based research are presented and discussed in this paper. For each of these years, this paper also explores the various innovations in NFS methodologies employed by the researchers to tackle different business problems. Furthe...\",\n \"Title: A review on the applications of neuro-fuzzy systems in business.\\nYear: 2018\\n\\nAbstract: This paper presents a review of the application of neuro-fuzzy systems (NFS) in business on the basis of the research articles issued in various reputed international journals and conferences during 2005–2015. The use of NFS for tackling various real world problems in different business domains has diversified significantly during this period. In effect NFS has emerged as a dominant technique for addressing various difficult research problems in business. Based on a detailed review of these research papers we have identified finance, marketing, distribution, business planning, information systems, production and operations as the main business application domains of NFS during this period. This paper also discusses the impact of NFS in various business domains and the trend of this application based research during this period. This paper also surveys the various innovations in NFS methodologies employed by the researchers to deal with different business problems in each of these years. Moreover the paper includes some articles published during 2016 in several international journals to present the latest progress in the application of NFS in various business domains.\",\n \"Title: Optimal Sensor Collaboration for Parameter Tracking Using Energy Harvesting Sensors.\\nYear: 2018\\n\\nAbstract: In this paper, we design an optimal sensor collaboration strategy among neighboring nodes while tracking a time-varying parameter using wireless sensor networks in the presence of imperfect communication channels. The sensor network is assumed to be self-powered, where sensors are equipped with energy harvesters that replenish energy from the environment. In order to minimize the mean square estim...\",\n \"Title: On Sequential Random Distortion Testing of Non-Stationary Processes.\\nYear: 2018\\n\\nAbstract: In this work, we propose a non-parametric sequential hypothesis test based on random distortion testing (RDT). RDT addresses the problem of testing whether or not a random signal, Ξ, observed in independent and identically distributed (i.i.d) additive noise deviates by more than a specified tolerance, τ, from a fixed model, ξ0. The test is non-parametric in the sense that the underlying signal dis...\",\n \"Title: Bounds on Channel Capacity of a Fiber Optic Channel with Memory\\nYear: 2018\\n\\nAbstract: The following topics are dealt with: learning (artificial intelligence); computational complexity; optimisation; probability; graph theory; channel coding; array signal processing; stochastic processes; decoding; millimetre wave communication.\",\n \"Title: Quality-of-Service in Multihop Wireless Networks: Diffusion Approximation.\\nYear: 2018\\n\\nAbstract: We consider a multihop wireless system. There are multiple source-destination pairs. The data from a source may have to pass through multiple nodes. We obtain a channel scheduling policy which can guarantee end-to-end mean delay for the different traffic streams. We show the stability of the network for this policy by convergence to a fluid limit. It is intractable to obtain the stationary distribution of this network. Thus we also provide a diffusion approximation for this scheme under heavy traffic. We show that the stationary distribution of the scaled process of the network converges to that of the Brownian limit. This theoretically justifies the performance of the system. We provide simulations to verify our claims.\",\n \"Title: An interpretable neuro-fuzzy approach to stock price forecasting.\\nYear: 2019\\n\\nAbstract: Stock price prediction is a complex and difficult task due to the chaotic behavior and high uncertainty in stock market prices. The design of a highly accurate, simple and intelligible forecasting model is of prime importance in this field. With this aim, a number of research studies have employed fuzzy rule-based systems for stock price forecasting. But the main focus has been on obtaining fuzzy systems with high accuracy and the interpretability aspect has been overlooked due to the assumption that the fuzzy rule-based systems are implicitly interpretable in the form of fuzzy rules which is not essentially true. This paper proposes an efficient and interpretable neuro-fuzzy system for stock price prediction using multiple technical indicators with focus on interpretability–accuracy trade-off. The interpretability of the system is ensured by: (1) rule base reduction via selection of the best rules using rule performance criteria to obtain an efficient and a compact rule base which is easily comprehendible and (2) constrained learning during model optimization stage so that simple constraints are imposed on the updates of fuzzy set parameters due to which the system remains interpretable and forecasting accuracy is not compromised. For experimental evaluation of the proposed system, daily stock data of Bombay Stock Exchange, CNX Nifty and S&P 500 stock indices are used. The simulation results show that the proposed system obtains a better balance between accuracy and interpretability than two other artificial intelligence techniques and two statistical techniques commonly used in stock price prediction.\",\n \"Title: On Random Distortion Testing Based Sequential Non-Parametric Hypothesis Testing<sup>*</sup>\\nYear: 2018\\n\\nAbstract: In this work, we propose a new method for sequential binary hypothesis testing. The approach is non-parametric in the sense that it does not assume any knowledge of signal distributions under each hypothesis. The proposed framework is based on Random distortion testing (RDT) which addresses the problem of testing whether or not a random signal, deviates by more than a specified tolerance, $\\\\tau$, from a fixed value, $\\\\xi_{0}$. We first state the problem setup and then discuss earlier approaches to solve the problem. We then propose a new sequential algorithm, T-SeqRDT, which is shown to control the probabilities of error while reducing the number of samples required to make a decision compared to the fixed-sample-size version of RDT. Finally, via simulations we compare T-SeqRDT to other algorithms and show its robustness compared to standard likelihood ratio based approaches.\",\n \"Title: An asymptotic approximation for TCP CUBIC\\nYear: 2019\\n\\nAbstract: AbstractIn this paper, we derive an expression for computing the average window size of a single TCP CUBIC connection under random losses. For this we consider a throughput expression for TCP CUBIC computed earlier under deterministic periodic packet losses. We validate this expression theoretically. We then use insights from the deterministic loss-based model to scale appropriately a sequence of Markov chains with random losses indexed by the probability of loss p. We show that this sequence converges to a limiting Markov chain as p tends to 0. The stationary distribution of the limiting Markov chain is then used to derive the average window size for small packet error rates. We then use a simple approximation to extend our current results with negligible queuing to a setup with multiple connections and non-negligible queuing. We validate our model and approximations via simulations.\",\n \"Title: Towards An Online Energy Allocation Policy For Distributed Estimation With Sensor Collaboration Using Energy Harvesting Sensors\\nYear: 2016\\n\\nAbstract: We study an energy allocation problem for distributed estimation with sensor collaboration, where collaboration refers to the act of sharing measurements with neighboring sensors prior to transmission to the fusion center, and the sensors are equipped with energy harvesters to replenish their power from the environment. Based on the statistics of the harvested energy and dynamics of energy flow at each sensor, we propose a provably efficient online energy allocation policy for distributed estimation with sensor collaboration. The proposed online policy relies on solving an offline non-convex optimization problem, in which the estimation distortion is minimized subject to energy and network topology constraints. We employ semidefinite programming to find the globallyoptimal solution of the non-convex problem. We show that the proposed online policy is asymptotically consistent and provide mean square error of the optimal offline solution over an infinite time horizon.\",\n \"Title: Novel benchmark database of digitized and calibrated cervical cells for artificial intelligence based screening of cervical cancer.\\nYear: 2016\\n\\nAbstract: The primary objective of this research work is to develop a novel benchmark database of digitized and calibrated, cervical cells obtained from slides of Papanicolaou smear test, which is done for screening of cervical cancer. This database can serve as a potential tool for designing, developing, training, testing and validating various artificial intelligence based systems for prognosis of cervical cancer by characterization and classification of Papanicolaou smear images. The database can also be used by other researchers for comparative analysis of working efficiencies of various machine learning and image processing algorithms. The database can be obtained by sending a request to the corresponding author or can be downloaded from http://digitalpapsmeardb.in/. Besides developing a rich machine learning database we have also presented a novel artificial intelligence based hybrid ensemble technique for efficient screening of cervical cancer by automated analysis of Papanicolaou smear images. The correct and timely diagnosis of cervical cancer is one of the major problems in the medical world. From the literature it has been found that different pattern recognition techniques can help them to improve in this domain. Papanicolaou smear (also referred to as Pap smear) is a microscopic examination of samples of human cells scraped from the lower, narrow part of the uterus, called cervix. A sample of cells after being stained by using Papanicolaou method is analyzed under microscope for the presence of any unusual developments indicating any precancerous and potentially precancerous developments. Abnormal findings, if observed are subjected to further precise diagnostic subroutines. Examining the cell images for abnormalities in the cervix provides grounds for provision of prompt action and thus reducing incidence and deaths from cervical cancer. It is the most popular technique used for screening of cervical cancer. Pap smear test, if done with a regular screening programs and proper follow-up, can reduce cervical cancer mortality by up to 80 % (Arbyn et al. Ann Oncol 21:48–458, 2010). The contribution of this paper is that we have created a rich machine learning database of quantitatively profiled and calibrated cervical cells obtained from Pap-smear test slides. The database so created consists of data of about 200 clinical cases (8091 cervical cells), which have been obtained from multiple health care centers, so as to ensure diversity in data. The Pap-smear slides were processed using a multi-headed digital microscope and images of cervical cells were obtained, which were then passed through various data preprocessing subroutines. After preprocessing the cells were morphologically profiled and scaled to obtain separate quantitative measurements of various features of cytoplasm and nucleus respectively. The cells in the database were carefully classified in different corresponding classes according to the latest 2001-Bethesda system of classification, by multiple cytotechnicians and histopathologists. In addition to this, we have also pioneered to apply a novel hybrid ensemble system to this database in order to evaluate the effectiveness of both novel database and novel hybrid ensemble technique to screen cervical cancer by categorization of Pap smear data. The paper also presents a comparative analysis of multiple artificial intelligence based classification algorithms for prognosis of cervical cancer. For evaluating the effectiveness and correctness of the digital database prepared in this work, authors implemented this database for training, testing and validating fifteen different artificial intelligence based machine learning algorithms. All the algorithms trained with this database presented commendable efficiency in screening of cervical cancer. For two-class problem all the algorithms trained with the digital database showed the efficiencies in the range of about 93 to 95 % while as in case of multi class problem algorithms expressed the efficiencies in the range of about 69 to 78 %. The results indicate that the novel digital database prepared in this work can be efficiently used for developing new machine learning based techniques for automated screening of cervical cancer. The results also indicate that hybrid ensemble technique is an efficient method for classification of pap-smear images and hence can be effectively used for diagnosis of cervical cancer. Among all the algorithms implemented, the hybrid ensemble approach outperformed and expressed an efficiency of about 98 % for 2-class problem and about 86 % for 7-class problem. The results when compared with the all the standalone classifiers were significantly better for both two-class and multi-class problems.\",\n \"Title: Artificial neural network based screening of cervical cancer using a hierarchical modular neural network architecture (HMNNA) and novel benchmark uterine cervix cancer database\\nYear: 2019\\n\\nAbstract: The work reported in this paper presents a novel hierarchical modular neural network architecture (HMNNA) for automated screening of cervical cancer. HMNNA consists of three neural networks trained specifically on different areas of problem space under consideration, and the trained networks are then arranged in a tree structure forming hierarchical modular neural network architecture. The three specialized neural networks are trained by Levenberg–Maarquardt neural network algorithm. As compared to the standard back propagation algorithm, Levenberg–Maarquardt is fast and stable for convergence with only one drawback, i.e., storage requirement for estimated Hessian Matrix. For training and testing of HMNNA, a huge primary database is created which contains 8091 cervical cell images pertaining to 200 clinical cases collected from two health care institutions of northern India. The raw cases of cervical cancer in the form of Pap smear slides were photographed under a multi-headed digital microscope. Individual cells were manually cropped off from these slide images which were then passed through a feature extraction module for morphological profiling. Each cell was calibrated on the basis of 40 features from both cytoplasm and nucleus. After profiling, these cells were vigilantly assigned cell classes as per the latest 2001-Bethesda system of cervical cancer cell classification, by trained cytotechnicians and histopathologists. HMNNA is also trained and tested on the Herlev Benchmark dataset created by the Denmark University, which consists of 1417 cervical cancer cells. Both the datasets have seven classes of diagnosis, i.e., superficial squamous, intermediate squamous, columnar, mild dysplasia, moderate dysplasia, severe dysplasia, and carcinoma in situ, corresponding to the level of abnormality in cervical cells. These datasets are available in public domain at http://digitalpapsmeardb.in/ and http://mde-lab.aegean.gr/index.php/downloads. The screening potential of the HMNNA is compared with 25 well-known machine learning algorithms available in MatlabR2016 (Machine learning and statistics toolbox 10.2) and monolithic neural network algorithms available in Matlab neural network pattern recognition toolbox. The HMNNA outperformed in all the 25 algorithms for both the datasets. For the Novel Benchmark database, it produced a classification accuracy of 95.32% with an F-value of 0.949310 and classification accuracy of 88.41% with an F-value of 0.89145 for the Herlev dataset. The screening potential of HMNNA was also evaluated and compared with the other diagnostic systems available in the recently published literature and was found to be performing much better than the counterparts on multiple parameters of performance evaluation.\",\n \"Title: Cross-App Tracking via Nearby Bluetooth Low Energy Devices.\\nYear: 2018\\n\\nAbstract: Today an increasing number of consumer devices such as head phones, wearables, light bulbs and even baseball bats, are Bluetooth-enabled thanks to the widespread support of the technology by phone manufacturers and mobile operating system vendors. The ability for any device to seamlessly connect and exchange information with smartphones via Bluetooth Low Energy (BLE) protocol promises unlimited room for innovation. However, it also brings about new privacy challenges. We show that the BLE protocol together with the Bluetooth permission model implemented in the Android and iOS operating systems can be used for cross-app tracking unbeknownst to the individuals.\\n\\nSpecifically, through experiments and analyses based on real-world smartphone data we show that by listening to advertising packets broadcasted by nearby BLE-enabled devices and recording information contained in them, app developers can derive fairly unique \\\"fingerprints\\\" for their users, which can be used for cross-app tracking, i.e., linking pseudonymous users of different apps to each other. We demonstrate that privacy protections put in place by the Bluetooth Special Interest Group, Google, and Apple are not sufficient to prevent such fingerprinting or to make cross-app tracking difficult to execute.\\n\\nOur main contribution is to demonstrate the feasibility of cross-app tracking using nearby BLE and raise awareness that changes are needed in order to prevent it from becoming widespread. We also propose mitigation strategies to decrease the feasibility of tracking using nearby BLE devices while preserving the utility of the BLE technology.\",\n \"Title: Queuing Theoretic Models for Multicast and Coded-Caching in Downlink Wireless Systems.\\nYear: 2018\\n\\nAbstract: We consider a server connected to $L$ users over a shared finite capacity link. Each user is equipped with a cache. File requests at the users are generated as independent Poisson processes according to a popularity profile from a library of $M$ files. The server has access to all the files in the library. Users can store parts of the files or full files from the library in their local caches. The server should send missing parts of the files requested by the users. The server attempts to fulfill the pending requests with minimal transmissions exploiting multicasting and coding opportunities among the pending requests. We study the performance of this system in terms of queuing delays for the naive multicasting and several coded multicasting schemes proposed in the literature. We also provide approximate expressions for the mean queuing delay for these models and establish their effectiveness with simulations.\",\n \"Title: Second Order and Moderate Deviation Analysis of a Block Fading Channel with Deterministic and Energy Harvesting Power Constraints.\\nYear: 2019\\n\\nAbstract: We consider a block fading additive white Gaussian noise (AWGN) channel with perfect channel state information (CSI) at the transmitter and the receiver. First, for a given codeword length and non-vanishing average probability of error, we obtain lower and upper bounds on the maximum transmission rate. We derive bounds for three kinds of power constraints inherent to a wireless transmitter. These include the canonical peak power constraint and average power constraint. In addition, we consider a time varying peak power constraint imposed by an emph{energy harvesting device}-a mechanism that powers many modern-day wireless transmitters. The bounds characterize emph{second order} deviation of finite blocklength coding rates from the channel capacity, which is in turn achieved by textit{water-filling} power allocation across time. The bounds obtained also indicate the rate enhancement possible due to CSI at the transmitter in the finite blocklength regime. Next, we provide bounds on the optimal exponent with which error probability drops to zero when channel coding rate is simultaneously allowed to approach capacity emph{at a certain rate}, as the codeword length increases. These bounds identify what is known as the moderate deviation regime of the block fading channel. We compare the bounds numerically to bring out the efficacy of our results.\",\n \"Title: A Lower Bound on Channel Capacity of a Nonlinear Fiber Optic Channel with Memory\\nYear: 2018\\n\\nAbstract: We consider a nonlinear fiber optic channel with memory and signal dependent noise. We provide an achievable rate via an i.i.d. complex Gaussian input. This improves on an existing bound. We also argue that our bound is close to the capacity of the channel.\",\n \"Title: Queueing Theoretic Models for Uncoded and Coded Multicast Wireless Networks With Caches\\nYear: 2022\\n\\nAbstract: We consider a server connected to several users over a shared finite capacity link. Each user is equipped with a cache. File requests at the users are generated as independent Poisson processes according to a popularity profile from a fixed finite library of files. The server has access to all the files in the library. Users can store parts of the files or full files from the library in their local caches. The server should send missing parts of the files requested by the users. The server attempts to fulfill the pending requests with minimal transmissions exploiting multicasting and coding opportunities among the pending requests. We consider a queue in which requests for the same file from different users is merged and transmitted simultaneously to all the requested users. We study and compare the performance of this queuing system in terms of queuing delays when LRU caches are used and when coded caching schemes proposed in the literature are used. We provide approximate expressions for the mean queuing delay for these models and establish their effectiveness with simulations. We extend the analysis to the case when transmission errors are also taken into account.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":131,"string":"131"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":67,"string":"67"}}},{"rowIdx":68,"cells":{"question_id":{"kind":"string","value":"Hang Yu"},"question":{"kind":"string","value":"Generate an abstract for the title \"AP-10K: A Benchmark for Animal Pose Estimation in the Wild.\" using the following items: animal pose estimation, benchmark, diversity, generalization ability, large-scale."},"answer":{"kind":"string","value":"Accurate animal pose estimation is an essential step towards understanding animal behavior, and can potentially benefit many downstream applications, such as wildlife conservation. Previous works only focus on specific animals while ignoring the diversity of animal species, limiting the generalization ability. In this paper, we propose AP-10K, the first large-scale benchmark for general animal pose estimation, to facilitate the research in animal pose estimation. AP-10K consists of 10,015 images collected and filtered from 23 animal families and 54 species following the taxonomic rank and high-quality keypoint annotations labeled and checked manually. Based on AP-10K, we benchmark representative pose estimation models on the following three tracks: (1) supervised learning for animal pose estimation, (2) cross-domain transfer learning from human pose estimation to animal pose estimation, and (3) intra- and inter-family domain generalization for unseen animals. The experimental results provide sound empirical evidence on the superiority of learning from diverse animals species in terms of both accuracy and generalization ability. It opens new directions for facilitating future research in animal pose estimation. AP-10k is publicly available at https://github.com/AlexTheBad/AP10K."},"correct_answer":{"kind":"string","value":"Accurate animal pose estimation is an essential step towards understanding animal behavior, and can potentially benefit many downstream applications, such as wildlife conservation. Previous works only focus on specific animals while ignoring the diversity of animal species, limiting the generalization ability. In this paper, we propose AP-10K, the first large-scale benchmark for general animal pose estimation, to facilitate the research in animal pose estimation. AP-10K consists of 10,015 images collected and filtered from 23 animal families and 54 species following the taxonomic rank and high-quality keypoint annotations labeled and checked manually. Based on AP-10K, we benchmark representative pose estimation models on the following three tracks: (1) supervised learning for animal pose estimation, (2) cross-domain transfer learning from human pose estimation to animal pose estimation, and (3) intra- and inter-family domain generalization for unseen animals. The experimental results provide sound empirical evidence on the superiority of learning from diverse animals species in terms of both accuracy and generalization ability. It opens new directions for facilitating future research in animal pose estimation. AP-10k is publicly available at https://github.com/AlexTheBad/AP10K."},"documents":{"kind":"list like","value":["Title: Argos: practical many-antenna base stations\nYear: 2012\n\nAbstract: Multi-user multiple-input multiple-output theory predicts manyfold capacity gains by leveraging many antennas on wireless base stations to serve multiple clients simultaneously through multi-user beamforming (MUBF). However, realizing a base station with a large number antennas is non-trivial, and has yet to be achieved in the real-world. We present the design, realization, and evaluation of Argos, the first reported base station architecture that is capable of serving many terminals simultaneously through MUBF with a large number of antennas (M >> 10). Designed for extreme flexibility and scalability, Argos exploits hierarchical and modular design principles, properly partitions baseband processing, and holistically considers real-time requirements of MUBF. Argos employs a novel, completely distributed, beamforming technique, as well as an internal calibration procedure to enable implicit beamforming with channel estimation cost independent of the number of base station antennas. We report an Argos prototype with 64 antennas and capable of serving 15 clients simultaneously. We experimentally demonstrate that by scaling from 1 to 64 antennas the prototype can achieve up to 6.7 fold capacity gains while using a mere 1/64th of the transmission power.","Title: A Time-Delay-Integration Cmos Image Sensor With Pipelined Charge Transfer Architecture\nYear: 2012\n\nAbstract: In this paper, we report a novel Time-Delay-Integration (TDI) CMOS image sensor for low-earth orbit (LEO) nano-satellite imaging application, where limited exposure time and unexpected flight fluctuations are major design challenges. The sensor features programmable integration time per stage, dynamic charge transfer path and tunable well capacity. A prototype chip of 1536x8 pixels was implemented using TSMC 0.18 mu m CMOS image sensor process. Photodiode and other transistors are floor-planned in different arrays, providing small pixel pitch of 3.25 mu m and high fill factor of 57%.","Title: XTree: A New XML Keyword Retrieval Model\nYear: 2009\n\nAbstract: As more and more data are represented and stored by XML format, how to query XML data has become an increasingly important research issue. Keyword search is a proven user-friendly way of querying HTML documents, and it is well suited to XML trees as well. However, it is still an open problem in XML keyword retrieval that which XML nodes are meaningful and reasonable to a query, how to find these nodes effectively and efficiently. In recent years, many XML keyword retrieval models have been presented to solve the problem, such as XRANK and SLCA. These models usually return the most specific results and discard most ancestral nodes. There may not be sufficient information for users to understand the returned results easily. In this paper, we present a new XML keyword retrieval model, XTree, which can cover every keyword node and return the comprehensive result trees. For XTree model, we propose Xscan algorithm for processing keyword queries and GenerateTree for constructing results. We analytically and experimentally evaluate the performances of our algorithms, and the experiments show that our algorithms are efficient.","Title: Eigenspaces from seriated graphs\nYear: 2005\n\nAbstract: The aim in this paper is to show how the problem of learning the modes of structural variation in sets of graphs can be solved by converting the graphs to strings. We commence by showing how the problem of converting graphs to strings, or seriation, can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision for problems including image segmentation and relaxation labelling. We detail the representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We show how to perform PCA on the strings delivered by our method. By projecting the seriated graphs on to the leading eigenvectors of the sample covariance matrix, we pattern spaces suitable for graph clustering.","Title: Fast rendering of foveated volumes in wavelet-based representation\nYear: 2005\n\nAbstract: A foveated volume can be viewed as a blending of multiple regions, each with a different level of resolution. It can be efficiently represented in the wavelet domain by retaining a small number of wavelet coefficients. We exploit the arrangement of those wavelet coefficients to achieve fast volume rendering. The running time is O(n2+m), where n is the width of the rendered image, and m is the number of wavelet coefficients retained for the foveated volume. Our algorithm consists of two phases. The first phase is a fast reconstruction of the super-voxels from the wavelet coefficients, and the second phase renders the super-voxels by carefully tracking rays with different thickness in the super-voxels. No expensive preprocessing on the wavelet coefficients is required. Hence, it is possible to interactively modify different viewing parameters like the transfer functions. A potential application of our algorithm is in remote visualization of large volume data-sets.","Title: Graph seriation using semi-definite programming\nYear: 2005\n\nAbstract: Graph seriation is concerned with placing the nodes of a graph in a serial order so that edge consecutive constraints are generally preserved. It is an important task in network analysis problem in routine and bioinformatics. In this paper we show how the problem of graph seriation can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision. The main contribution of the paper is to detail the matrix representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We illustrate the utility of the method for graph-matching and graph-clustering, where it is shown to offer advantages to the graph-spectral approach to seriation.","Title: A new indexing strategy for XML keyword search\nYear: 2010\n\nAbstract: With the rapid increase of XML documents on the web, how to index, store and retrieve these documents has become a very popular and valuable problem. At present, there are two normal ways of retrieving XML documents. One is structure-based retrieval; the other is keyword-based retrieval. However, XML keyword search is becoming more and more popular because it is easy to master and manipulate. In XML keyword search system, a key problem is how to store the structure information into XML indices efficiently. At present, Dewey numbers are often used to label XML nodes in XML indices. However, Dewey numbers may lead to redundancy in XML indices. In this paper, we propose a new labeling method called LAF numbers for XML indices and we device a new indexing structure called Two-Layer index for XML keyword retrieval systems. At last, we have conducted an extensive experimental study and the experimental results show that our indexing method achieves better space efficiency than prevailing Dewey-number-based indexing method.","Title: Copula Gaussian graphical model for discrete data.\nYear: 2013\n\nAbstract: Copula Gaussian graphical models are capable of describing dependencies between a large number of heterogeneous variables. In this paper, low-complexity algorithms are proposed for learning copula Gaussian graphical models from discrete data. The proposed approach is Monte-Carlo expectation maximization: in the E-step, an efficient Gibbs sampler is applied, and in the M-step, the sparse graphical model is inferred by solving a penalized maximize likelihood problem. The regularization parameter is determined through the BINCO method proposed by Li et al. Numerical results for both synthetic and real data demonstrate the effectiveness of the proposed approach.","Title: Clonal selection algorithm with immunologic regulation for function optimization\nYear: 2005\n\nAbstract: Based on the Antibody Clonal Selection Theory of immunology, four immunologic regulation operators inspired by immune regulation mechanism of biology immune system are presented in this paper, and a corresponding algorithm, Immunologic Regulation Clonal Selection Algorithm (IRCSA), is put forward. The essential of immunologic regulation operators is to make fine adjustment among the candidates of the algorithm so as to make interrelations between antibodies more complicated and improve the stability, robustness and accuracy of the algorithm. Numeric experiments of function optimization indicate that the new algorithm is effective and useful.","Title: A 10gb/S Wire-Line Transceiver With Half Rate Period Calibration Cdr\nYear: 2009\n\nAbstract: This paper presents the design of a 10Gb/s low power wire-line transceiver in 65nm CMOS process with IV supply voltage. The transmitter occupies an area of 430 mu m x 240 mu m, consumes 50.56mW power and has a 5-order programmable pre-emphasis equalizer. The receiver occupies an area of 300 mu m x 500 mu m. With the novel half rate period calibration clock data recovery (CDR) circuit, the receiver consumes only 52mW power. The receiver combines a low power wideband programmable continuous time linear equalizer (CTLE) and a 3-order decision feedback equalizer (DEE).","Title: ArgosV2: a flexible many-antenna research platform\nYear: 2013\n\nAbstract: Many-antenna base stations are a rapidly growing field in wireless research. A plethora of new theoretical techniques have been recently proposed for many-antenna base stations and networks. However, without experimental validation, it is difficult or impossible to predict the practicality and performance of these techniques in real hardware, under complex, rapidly varying, real-world conditions. Indeed, there is a significant demand for a flexible many-antenna research platform which supports rapid prototyping and validation of new massive-MIMO techniques. Leveraging our experience building Argos, a 64-antenna base station prototype, we have designed and built ArgosV2, a compact, powerful, and scalable many-antenna research platform based on WARP. In addition to the physical hardware and mechanical design, we are developing a software framework, ArgosLab, which will provide synchronization and channel estimation, greatly reducing the development effort for a wide range of massive-MIMO techniques. ArgosV2 is intended to provide ultimate scalability and programmability for experimental massive-MIMO research. The modular architecture and real-time capability of ArgosV2 can support up to 100s of base station antennas and 10s of users with streaming applications. For our demonstration, we will unveil a 96-antenna base station which supports real-time streaming applications to 32 users simultaneously.","Title: Context-Based Hierarchical Unequal Merging for SAR Image Segmentation.\nYear: 2013\n\nAbstract: This paper presents an image segmentation method named Context-based Hierarchical Unequal Merging for Synthetic aperture radar (SAR) Image Segmentation (CHUMSIS), which uses superpixels as the operation units instead of pixels. Based on the Gestalt laws, three rules that realize a new and natural way to manage different kinds of features extracted from SAR images are proposed to represent superpix...","Title: Data broadcasting using mobile FM radio: design, realization and application\nYear: 2011\n\nAbstract: In this work, we offer a novel system, MicroStation (μStation) that allows ubiquitous data broadcasting applications using the FM radio on mobile devices such as smartphones. μStation includes two key modules to enable data broadcasting based on existing mobile FM radio hardware. Channel Selector assigns different FM channels to neighboring μStation broadcasters to avoid collision and guides μStation listeners to find their broadcasting of interest. Data Codec realizes bit-level communication between mobile devices through existing FM radio hardware. We describe an implementation of μStation on the Nokia N900 smartphone, and provide low-level APIs and services to support application development. We also demonstrate two representative applications: Facebook-FM and Sync-Flash. These applications demonstrate the capability of μStation to readily enable a new class of ubiquitous data broadcasting applications on mobile devices.","Title: Developing an ontology for the U.S. patent system\nYear: 2011\n\nAbstract: The past few years have experienced an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous information domains making it a challenging task to gather information. In this paper, we develop an ontology to standardize the representation of the patent system in order to overcome the heterogeneity and integrate information from the patent document, court case and file wrapper domains. Through a use case in the bio domain erythropoietin, we demonstrate how this ontology can be used as a tool to improve the learning curve of users gathering information across these multiple information domains. The proposed ontology provides the required semantics to develop automated tools for a variety of purposes including Information Retrieval (IR) and analytics.","Title: BeamAdapt: energy efficient beamsteering on mobile devices\nYear: 2010\n\nAbstract: All current mobile devices are omni directional in transmission, which not only limits device energy efficiency but also poses a significant challenge toward network capacity through inter-link interference. In this work, we make mobile devices directional with beamsteering. By allowing a dynamic number of antennas in beamsteering, we reveal an important tradeoff between device energy efficiency and network capacity. We then provide a distributed algorithm called BeamAdapt that allows each mobile device in the network to closely approach the optimal tradeoff, with minimum aggregated device power to achieve certain network capacity. We also offer a cellular system realization of BeamAdapt as well as a Qualnet-based evaluation. The results show the effectiveness of BeamAdapt in device power reduction without sacrificing network throughput.","Title: ListOPT: learning to optimize for XML ranking\nYear: 2011\n\nAbstract: Many machine learning classification technologies such as boosting, support vector machine or neural networks have been applied to the ranking problem in information retrieval. However, since the purpose of these learning-torank methods is to directly acquire the sorted results based on the features of documents, they are unable to combine and utilize the existing ranking methods proven to be effective such as BM25 and PageRank. To solve this defect, we conducted a study on learning-to-optimize, which is to construct a learning model or method for optimizing the free parameters in ranking functions. This paper proposes a listwise learning-to-optimize process ListOPT and introduces three alternative differentiable query-level loss functions. The experimental results on the XML dataset of Wikipedia English show that these approaches can be successfully applied to tuning the parameters used in an existing highly cited ranking function BM25. Furthermore, we found that the formulas with optimized parameters indeed improve the effectiveness compared with the original ones.","Title: Two-step 3-dimensional sketching tool for new product development\nYear: 2004\n\nAbstract: This paper discusses a two-step virtual reality based conceptual design tool that enables industrial designers to create sketches of their ideas in 3-dimensional space in real time. In the developed sketching tool, the rough shapes of products are generated by tracing the trajectory of the data-gloves worn by the designer. In the model a practical solution is provided to reduce the generation of unnecessary control points. This is achieved by representing each control point by a spherical volume. Once the rough sketching is completed, NURBS surfaces are constructed by the limited number of reference points that are selected from the initial sketch by using a virtual pen. The two-steps sketching technique enables designers to perform their artistic characteristics freely in an intuitive environment and also enables designers to generate parametric representations of the surfaces to be used in CAD/CAM systems for further analysis.","Title: Testing BPEL-based Web Service Composition Using High-level Petri Nets\nYear: 2006\n\nAbstract: This paper proposes a technique for analysis and testing BPEL-based web service composition using High-level Petri Nets. To illustrate how these compositions are verified, the relationships between BPEL-based web service composition and High-level Petri Nets is constructed. By analyzing the structure of web service composition based on BPEL, the corresponding HPN is constructed. The dynamism and occurrence are presented in HPN with guard expression with coloured token. After translation, the equivalent HPN of the web service composition based on BPEL can be verified on existing mature tool, and the related researches on HPN, e.g. testing coverage and reduction techniques that have been studied deeply, can be employed in testing of web service composition based on BPEL, optimized test case can be generated based on the HPN translated. An example is provided to illustrate the translation ruled and the automatic verify progress.","Title: Graph matching using spectral embedding and alignment\nYear: 2004\n\nAbstract: This paper describes how graph-spectral methods can be used to transform the node correspondence problem into one of point-set alignment. We commence by using the ISOMAP algorithm to embed the nodes of a graph in a low-dimensional Euclidean space. With the nodes in the graph transformed to points in a metric space, we can recast the problem of graph matching into that of aligning the points. Here, we use a variant of the Scott and Longuet-Higgins algorithm to find point correspondences. We experiment with the resulting algorithm on a number of real-world problems.","Title: A neural contextual model for detecting perceptually salient contours\nYear: 2009\n\nAbstract: A computational model, inspired by visual cortical mechanisms of contextual modulation, is presented in this paper, and is applied to detect perceptually salient contours. The presented model incorporates two mechanisms of contextual modulation, surround suppression and collinear facilitation. An oriented filterbank generated by Gaussian derivatives and their Hilbert transform is proposed for pre-processing. The operators of surround suppression and collinear facilitation are applied to the orientation energy resulting from the outputs of oriented filterbank. To avoid augmenting the noise when the facilitation operator enhances the saliency parts, we employ a contrast enhancement transformation for the facilitation operator. For drawing the binary contours, we present an automatic thresholding approach for post-processing. The performance of our model is tested by artificial images with heavy noise and nature images with texture background. Results show that the model has a good performance on extracting the salient contours from images.","Title: Adaptive Top-k Algorithm in SLCA-Based XML Keyword Search\nYear: 2010\n\nAbstract: Computing top-k results matching XML queries is gaining importance due to the increasing of large XML repositories. In this paper, we propose a novel two-layer-based index construction and associated algorithms for efficiently computing top-k results for SLCA-based XML keyword search. We have conducted expensive experiments and the results show great advantage on efficiency compared with existing approaches.","Title: Integrated Optimization of Video Server Resource and Streaming Quality Over Best-Effort Network\nYear: 2009\n\nAbstract: A video streaming server needs to adapt its source/channel encoding parameters (or configurations) to changes in network conditions and to differences in users' connection profiles. The adaptation can be achieved by adjusting parameters such as frame rate, error protection ratio, and resolution. Ideally, the server should adapt the serving configurations with respect to the current network and user conditions to improve received video quality. However, adaptations that optimize playable frame rate require intensive computation, and storing all possible configurations requires a tremendous amount of storage. This brings forth the issues of how to obtain good video quality and reduce server resources usage at the same time. We address this issue in this paper. Our approach is based on the observation that transcoding between certain configurations can be performed very efficiently. We propose a framework to compute a set of configurations to store on the server by considering two opposing goals: (a) maximizing expected received quality of the video, and (b) minimizing server resource usage by lowering transcoding cost and expected number of switches between configurations. The second objective also reduces the number of configurations, and therefore reduces the total storage required. Our framework models the relationship among different configurations in a partial order, formulates the search of a good set of configurations as an energy minimization problem, and we use techniques in image segmentation to solve the problem. Experimental results show that our framework relieves the server load and increases the number of clients served, while only slightly reducing the expected frame rate.","Title: Power management of MIMO network interfaces on mobile systems\nYear: 2012\n\nAbstract: High-speed wireless network interfaces are among the most power-hungry components on mobile systems. This is particularly true for multiple-input-multiple-output (MIMO) network interfaces which use multiple RF chains simultaneously. In this paper, we present a novel power management solution for MIMO network interfaces on mobile systems, called antenna management. The key idea is to adaptively disable a subset of antennas and their RF chains to reduce circuit power consumption, when the capacity improvement of using a large number of antennas is small. Antenna management judiciously determines the number of active antennas to minimize energy per bit while satisfying the data rate requirement. This work provides both theoretical framework and system design of antenna management. We first present an algorithm that efficiently solves the problem of minimizing energy per bit and, then offer its 802.11n-compliant system designs. We employ both MATLAB-based simulation and prototype-based experiment to validate the energy efficiency benefit of antenna management. The results showthat antenna management can achieve 21% one-end energy per bit reduction to the front end of the MIMO network interface, compared to a static MIMO configuration that keeps all antennas active.","Title: Combining strategies for XML retrieval\nYear: 2010\n\nAbstract: This paper describes Peking University's approaches to the Ad Hoc, Data Centric and Relevance Feedback track. In Ad Hoc track, results for four tasks were submitted, Efficiency, Restricted Focused, Relevance In Context and Restricted Relevance In Context. To evaluate the relevance between documents and a given query, multiple strategies, such as Two-Step retrieval, MAXLCA query results, BM25, distribution measurements and learn-to-optimize method are combined to form a more effective search engine. In Data Centric track, to gain a set of closely related nodes that are collectively relevant to a given keyword query, we promote three factors, correlation, explicitnesses and distinctiveness. In Relevance Feedback track, to obtain useful information from feedbacks, our implementation employs two techniques, a revised Rocchio algorithm and criterion weight adjustment.","Title: Vision-based 3D finger interactions for mixed reality games with physics simulation\nYear: 2008\n\nAbstract: Mixed reality applications can provide users with enhanced interaction experiences by integrating virtual and real world objects in a mixed environment. Through the mixed reality interface, a more realistic and immersive control style is achieved compared to the traditional keyboard and mouse input devices. The interface proposed in this paper consists of a stereo camera, which tracks the user's hands and fingers robustly and accurately in the 3D space. To enable a physically realistic experience in the interaction, a physics engine is adopted for the simulating the physics of virtual object manipulation. The objects can be picked up and tossed with physical characteristics, such as gravity and collisions which occur in the real world. Detection and interaction in our system is fully computer-vision based, without any markers or additional sensors. We demonstrate this gesture-based interface using two mixed reality game implementations: finger fishing, in which a player can simulate fishing for virtual objects with his/her fingers as in a real environment, and Jenga, which is a simulation of the well-known tower building game. A user study is conducted and reported to demonstrate the accuracy, effectiveness and comfort of using this interactive interface.","Title: Manifold embedding for shape analysis\nYear: 2010\n\nAbstract: Shape analysis played important role in computer vision based tasks. The importance of shape information relies that it usually contains perceptual information, and thus can be used for high level visual information analysis. Currently, there are many ways that shapes can be represented as a structural manner using graphs. Hence shapes can be analyzed by using graph methods. This paper describes how graph-spectral methods can be used to transform the node correspondence problem into one of point-sets alignment. We commence by using the ISOMAP algorithm to embed the nodes of a graph in a low-dimensional Euclidean space. With the nodes in the graph transformed to points in a metric space, we can recast the problem of graph-matching into that of aligning the point-sets. Here we use semidefinite programming to develop a robust point-sets correspondences algorithm. Variations in graph structure using the covariance matrix for corresponding embedded point-positions is captured. We construct a statistical point distribution model for the embedded node positions using the eigenvalues and eigenvectors of the covariance matrix. We show how to use this model to project individual graph, i.e. shape into the eigenspace of the point position covariance matrix. We illustrate the utility of the resulting method for shape analysis and recognition on COIL and MPEG-7 databases.","Title: Modeling Spatially-Dependent Extreme Events With Markov Random Field Priors\nYear: 2012\n\nAbstract: A novel spatial model for extreme events is proposed. The model may for instance be used to describe the occurrence of catastrophic events such as earthquakes, floods, or hurricanes in certain regions; it may therefore be relevant for, e.g., weather forecasting, urban planning, and environmental assessment. The model is derived from the following ideas: The above-threshold values at each location are assumed to follow a generalized Pareto (GP) distribution. The GP parameters are coupled across space through Markov random fields, in particular, thin-membrane models. The latter are inferred through an empirical Bayes approach. Numerical results are presented for synthetic and real data (related to hurricanes in the Gulf of Mexico).","Title: Perceptual Weighting in LSP-Based Multi-Description Coding for Real-Time Low-Bit-Rate Voice Over IP\nYear: 2005\n\nAbstract: This paper focuses on improving an LSP-based multi-description coding (MDC) scheme for concealing losses when real-time CELP-coded speech data is sent over IP networks. In that scheme, LSP vectors are interleaved because they are highly correlated and can be reconstructed by interpolations when packets are delayed or lost. However, excitation vectors are random in nature and must be replicated in order to conceal losses. To avoid increasing the bit rate of the encoded speech, the excitation vectors are generated from longer subframes. This leads to lower quality of the decoded speech because noise from outside formant regions is over-emphasized, and more excitation information is extracted there. To improve quality, we propose in this paper to modify the perceptual-weighting filter (PWF) in the coder in order to adjust the allocation of noise inside and outside formant regions. We further study a method that selects the PWF in such a way that maintains high quality of the LSP-based MDC across different voice streams and loss scenarios. Experimental results on FS-1016 CELP (4800 bps), ITU G.723.1 ACELP (5300 bps), and ITU G.723.1 MP-MLQ (6300 bps) demonstrate noticeable improvements in decoding quality","Title: Machine learning with seriated graphs\nYear: 2005\n\nAbstract: The aim in this paper is to show how the problem of learning the class-structure and modes of structural variation in sets of graphs can be solved by converting the graphs to strings. We commence by showing how the problem of converting graphs to strings, or seriation, can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision for problems including image segmentation and relaxation labelling. We detail the representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We show how the strings delivered by our method can be used for graph-clustering and the construction of graph eigenspaces.","Title: Null controllability for a fourth order parabolic equation.\nYear: 2009\n\nAbstract: In the paper, the null interior controllability for a fourth order parabolic equation is obtained. The method is based on\n Lebeau-Rabbiano inequality which is a quantitative unique continuation property for the sum of eigenfunctions of the Laplacian.","Title: Inferring Brain Networks through Graphical Models with Hidden Variables.\nYear: 2011\n\nAbstract: Inferring the interactions between different brain areas is an important step towards understanding brain activity. Most often, signals can only be measured from some specific brain areas (e.g., cortex in the case of scalp electroencephalograms). However, those signals may be affected by brain areas from which no measurements are available (e.g., deeper areas such as hippocampus). In this paper, the latter are described as hidden variables in a graphical model; such model quantifies the statistical structure in the neural recordings, conditioned on hidden variables, which are inferred in an automated fashion from the data.","Title: Copula Gaussian multiscale graphical models with application to geophysical modeling\nYear: 2012\n\nAbstract: Gaussian Multiscale graphical models are powerful tools to describe high-dimensional spatial data; they capture longrange statistical dependencies among distant sites by introducing coarser scales. However, such models are only applicable to Gaussian data. In this paper, a new class of copula Gaussian multiscale graphical models is proposed which possesses rich modeling capabilities and computational efficiency while eliminating the Gaussian assumption. Numerical results are presented for synthetic data as well as data from a few applications in geophysics - models of sea surface temperature and Asian rainfall patterns.","Title: Developing a comprehensive patent related information retrieval tool\nYear: 2011\n\nAbstract: In recent years, there has been a massive growth of regulatory and related information available online. This information is distributed across many different domains creating a problem for accessing and managing this data. This paper proposes a framework to access information across two such domains - patents and court cases. The framework is designed to boost the value of a set of patents based on information available in court cases by identifying and cross-referencing mutual information in the two domains. We test our framework by constructing a use case involving the hormone erythropoietin. A corpus of 1150 patents (including 135 closely related patents) and 30 court cases is gathered. Challenges associated with such integration and future plans are briefly discussed.","Title: Retrieving information across multiple, related domains based on user query and feedback: application to patent laws and regulations\nYear: 2010\n\nAbstract: In this paper, we present a framework that can process user query for retrieval of information from documents of different properties across multiple domains, with specific application to patent laws and regulations. A case example is given to demonstrate how results from multiple domain searches can be combined using ontology and cross referencing. A user feedback mechanism is also discussed in this paper.","Title: Adaptive RF chain management for energy-efficient spatial-multiplexing MIMO transmission\nYear: 2009\n\nAbstract: We present the theoretical foundation, implementation, and experimental evaluation of a novel power-saving mechanism for wireless transmission from multiple-input multiple-output (MIMO) transceivers, called RF chain management. RF chain management seeks to minimize the energy per bit for MIMO transmission, via adaptively choosing the optimal RF chain configuration, and satisfies the minimum data rate requirement at the same time. Our simulation shows that up to 45% and averagely 23% energy per bit reduction can be achieved. We have also built a prototype based on the WARP platform, and our experimental results have proved the feasibility of RF chain management in real systems and under realistic channels.","Title: An ontology-based interactive tool to search documents in the U.S. patent system\nYear: 2011\n\nAbstract: The past few years have seen an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous and distributed information sources making it very challenging to retrieve information across multiple domains. In this demonstration, we present a tool that enables users to simultaneously search multiple information domains in the patent system. The presented tool is built upon the Patent System Ontology, which provides both a standardized representation of the patent system domain and required semantics to integrate the various information domains [1], [2]. The tool provides features such as integration with a biomedical knowledge base and recommendations for related articles. Future additions to the tool will provide features to analyze the data both statistically and visually to aid in research. We demonstrate how this tool can be helpful in expediting search and information retrieval in an intelligent and convenient way through a use case in the bio domain -- erythropoietin.","Title: String Kernels for Matching Seriated Graphs\nYear: 2006\n\nAbstract: Graph seriation allows the nodes of a graph to be placed in a string order, and then matched using string alignment algorithms. Prior work has used Bayesian methods to derive the string edit costs required in matching. The aim in this paper is to demonstrate how the matching of seriated graphs can be kernelised. To do this we make use of string kernels and show how the parameters of the kernels can be linked to edge density. We illustrate that the graph edit distances computed using the string kernel can be used for graph clustering.","Title: Beamsteering on Mobile Devices: Network Capacity and Client Efficiency\nYear: 2010\n\nAbstract: Current and emerging mobile devices are omni directional in wireless\ncommunication. Such omni directionality not only limits device energy\nefficiency but also poses a significant challenge toward the capacity of\nwireless networks through inter-link interference. In this work, we seek to\nmake mobile clients directional with beamsteering. We first demonstrate that\nbeamsteering is already feasible to mobile devices such as Netbooks and eBook\nreaders in terms of form factor, power efficiency, and device mobility. We\nfurther reveal that beamsteering mobile clients face a unique challenge to\nbalance client efficiency and network capacity. There is an optimal operating\npoint for a beamsteering mobile client in terms of the number of antennas and\ntransmit power that achieve the required capacity with lowest power. Finally,\nwe provide a distributed algorithm called BeamAdapt that allows each client to\nclosely approach its optimal point iteratively without central coordination. We\nalso offer a cellular system realization of BeamAdapt. Using Qualnet-based\nsimulation, we show that BeamAdapt with four antennas can reduce client power\nconsumption by 55% while maintaining a required network throughput for a\nlarge-scale network, compared to the same network with omni directional mobile\nclients.","Title: Beamforming on mobile devices: a first study\nYear: 2011\n\nAbstract: In this work, we report the first study of an important realization of directional communication, beamforming, on mobile devices. We first demonstrate that beamforming is already feasible on mobile devices in terms of form factor, device mobility and power efficiency. Surprisingly, we show that by making an increasingly profitable tradeoff between transmit and circuit power, beamforming with state-of-the-art integrated CMOS implementations can be more power-efficient than its single antenna counterpart. We then investigate the optimal way of using beamforming in terms of device power efficiency, by allowing a dynamic number of active antennas. We propose a simple yet effective solution, BeamAdapt, which allows each mobile client in a network to individually identify the optimal number of active antennas with guaranteed convergence and close-to-optimal performance. We finally report a WARP-based prototype of BeamAdapt and experimentally demonstrate its effectiveness in realistic environments, and then complement the prototype-based experiments with Qualnet-based simulation of a large-scale network. Our results show that BeamAdapt with four antennas can reduce the power consumption of mobile clients by more than half compared to a single antenna, while maintaining a required network throughput.","Title: Fully utilize feedbacks: language model based relevance feedback in information retrieval\nYear: 2011\n\nAbstract: Relevance feedback algorithm is proposed to be an effective way to improve the precision of information retrieval. However, most researches about relevance feedback are based on vector space model, which can't be used in other more complicated and powerful models, such as language model and logic model. Meanwhile, other researches are conceptually restricted to the view of a query as a set of terms, and so cannot be naturally applied to more general case when the query is considered as a sequence of terms and the frequency information of a query tern is considered. In this paper, we mainly focuses on relevant feedback Algorithm based on language model. We use a mixture model to describe the process of generating document and use EM to solve model's parameters. Our research also employs semi-supervised learning to calculate collection model and proposes an effective way to obtain feedback from irrelevant documents to improve our algorithm.","Title: System optimization of a 5.8 GHz ETC receiver using Memetic algorithm\nYear: 2011\n\nAbstract: ETC (Electronic Tolling Collection) systems develop rapidly in China in order to relieve the traffic congestion. As the key component of the ETC system, the design of the Radio Frequency (RF) transceiver is usually a tedious and experienced based work due to its high non-linearity. An automatic system level optimization method based on Memetic algorithm (MA) is proposed in this paper. A fitness function describing the relationship between receiver output signal-to-noise ratio (SNRout) and 9 system level parameters was derived and was optimized by the MA method. The correctness of the MA method was verified by the ADS simulation. A close result was obtained and the effects of the 9 parameters on the SNRout were discussed. The future design of the whole transceiver system can be based on this method.","Title: Membrane Sculpting By F-Bar Domains Studied By Molecular Dynamics Simulations\nYear: 2013\n\nAbstract: Interplay between cellular membranes and their peripheral proteins drives many processes in eukaryotic cells. Proteins of the Bin/Amphiphysin/Rvs (BAR) domain family, in particular, play a role in cellular morphogenesis, for example curving planar membranes into tubular membranes. However, it is still unclear how F-BAR domain proteins act on membranes. Electron microscopy revealed that, in vitro, F-BAR proteins form regular lattices on cylindrically deformed membrane surfaces. Using all-atom and coarse-grained (CG) molecular dynamics simulations, we show that such lattices, indeed, induce tubes of observed radii. A 250 ns all-atom simulation reveals that F-BAR domain curves membranes via the so-called scaffolding mechanism. Plasticity of the F-BAR domain permits conformational change in response to membrane interaction, via partial unwinding of the domains 3-helix bundle structure. A CG simulation covering more than 350 mu s provides a dynamic picture of membrane tubulation by lattices of F-BAR domains. A series of CG simulations identified the optimal lattice type for membrane sculpting, which matches closely the lattices seen through cryo-electron microscopy.","Title: Extreme-value graphical models with multiple covariates\nYear: 2014\n\nAbstract: To assess the risk of extreme events such as hurricanes and floods, it is crucial to develop accurate extreme-value statistical models. Extreme events often display heterogeneity, varying continuously with a number of covariates. Previous studies have suggested that models considering covariate effects lead to reliable estimates of extreme value distributions. In this paper, we develop a novel model to incorporate the effects of multiple covariates. Specifically, we analyze as an example the extreme sea states in the Gulf of Mexico, where the distribution of extreme wave heights changes systematically with location and wind direction. The block maxima at each location and sector of wind direction are assumed to follow the Generalized Extreme Value (GEV) distribution. The GEV parameters are coupled across the spatio-directional domain through a graphical model, particularly, a multidimensional thin-membrane model. Efficient learning and inference algorithms are then developed based on the special characteristics of the thin-membrane model. Numerical results for both synthetic and real data indicate that the proposed model can accurately describe marginal behavior of extreme events.","Title: Modeling spatial extremes via ensemble-of-trees of pairwise copulas\nYear: 2014\n\nAbstract: Assessing the risk of extreme events in a spatial domain, such as hurricanes, floods and droughts, presents unique significance in practice. Unfortunately, the existing extreme-value statistical models are typically not feasible for practical large-scale problems. Graphical models are capable of handling enormous number of variables, yet have not been explored in the realm of extreme-value analysis. To bridge the gap, an extreme-value graphical model is introduced in this paper, i.e., ensemble-of-trees of pairwise copulas (ETPC). In the proposed graphical model, extreme-value marginal distributions are stitched together by means of pairwise copulas, which in turn are the building blocks of the ensemble of trees. By exploiting this particular structure, novel efficient inference algorithms are derived that are applicable to large-scale statistical problems involving extreme values. It is proven that, under mild conditions, the ETPC model exhibits the favorable property of tail-dependence between an arbitrary pair of sites (variables), and therefore is reliable to capture the dependence between extremes at different sites. Real data results further demonstrate the advantages of the ETPC model.","Title: Network inference and change point detection for piecewise-stationary time series\nYear: 2014\n\nAbstract: Graphical models are powerful tools to describe complex systems. Especially sparse graphical models are currently en vogue, as they allow us to infer network structure from multiple time series (e.g., functional brain networks from multichannel electroencephalograms). So far, most of the literature deals with stationary time series, whereas real-life time series often exhibit non-stationarity. In this paper, techniques are proposed to infer graphical models from piecewise stationary time series; first change point are detected in the time series, and then graphical models are inferred for each stationary segment. Specifically, a low-complexity algorithm based on Pruned Exact Linear Time method is proposed to identify change points. Copula Gaussian graphical models (with and without hidden variables) are then generated for each stationary segment. The crux of the proposed approach is that it determines the number and location of the change points as well as the graphical models in a fully automated manner. Results for both synthetic data and scalp electroencephalograms of epileptic seizure patients are provided to validate the model.","Title: Sensor fault detection by sparsity optimization\nYear: 2014\n\nAbstract: Measurement faults in control systems may result in permanent damages to the system components. Therefore, sensor validation is essential before the measurements are used for any system reconfiguration. In this paper, a statistical approach for sensor fault identification is proposed. Specifically, the potential sensor fault is assumed to be an additive bias term in the measurement model. The problem of fault identification is formulated as a least-squares optimization problem with an ℓ1 penalty on the bias term. An algorithm is further introduced to determine the regularization parameter automatically. Experimental results show that the proposed method can accurately detect multiple sensor failures from noisy measurements.","Title: Combating inter-cell interference in 802.11ac-based multi-user MIMO networks\nYear: 2014\n\nAbstract: In an 802.11ac-based MU-MIMO network comprised of multiple cells1, inter-cell interference allows only a single AP to serve its clients at the same time, significantly limiting the network capacity. In this work, we overcome this limitation by letting the APs and clients in interfering cells coordinately cancel the inter-cell interference using their antennas for beamforming. To achieve such coordinated interference cancellation in a practical way, we propose a novel two-step optimization. First, without requiring any channel knowledge, each AP and client optimizes the use of its antennas for either data communication or inter-cell interference cancellation, in order to maximize the total number of deliverable streams in the MU-MIMO network. Second, with only partial channel knowledge, each AP and client optimizes their beamforming weights after the optimal antenna usage has been identified in the first step. Our solution, CoaCa, integrates this two-step optimization into 802.11ac with small modifications and negligible overhead, allowing each AP and client to locally perform the two-step optimization. Our experimental evaluation indicates that for a MU-MIMO network with two cells, by cancelling the inter-cell interference CoaCa can convert the majority of the expected number of streams increase (50%-67%) into network capacity improvement (41%-52%).","Title: A dual-exposure in-pixel charge subtraction CTIA CMOS image sensor for centroid measurement in star trackers\nYear: 2014\n\nAbstract: In this work, we present a CMOS image sensor for star centroid measurement in star trackers. The analysis of the star tracker system shows that long integration will cause \"tail effect\" in the star image. It significantly reduces the signal magnitude, which in turn increases the centroiding errors. In order to capture limited photons generated from dim stars within shortened integration time, we propose a new capacitive transimpedance amplifier (CTIA) pixel architecture with a small integration capacitor. On the other hand, bright stars can easily saturate the pixels, which can also induce significant measurement errors. To avoid pixel saturation, the pixel is able to perform in-pixel charge subtraction based on photocurrent thresholding. In order to validate the pixel design, we have fabricated a test chip consisting of a 4×4 pixel array using Global Foundry 65 nm mixed signal CMOS process.","Title: Spatio-temporal graphical models for extreme events\nYear: 2014\n\nAbstract: We propose a novel statistical model to describe spatio-temporal extreme events. The model can be used to estimate extreme-value temporal pattern such as seasonality and trend, and further to predict the distribution of extreme events in the future. The basic idea is to explore graphical models to capture the highly structured dependencies among extreme events measured in time and space. More explicitly, we first assume the single observation at each location and time point follows a Generalized Extreme Value (GEV) distribution. The spatio-temporal dependencies are further encoded via graphical models imposed on the GEV parameters. We develop efficient learning and inference algorithms for the resulting non-Gaussian graphical model. Results of both synthetic and real data demonstrate the effectiveness of the proposed approach.","Title: Design and characterization of radiation-tolerant CMOS 4T Active Pixel Sensors\nYear: 2014\n\nAbstract: The design and radiation characterization of pinned photodiode 4T Active Pixel Sensors (APS) is presented in this paper. Four types of pixel layout are characterized and irradiated by 60Co γ-rays up to 170krad(Si). A variety of radiation hardening techniques are applied in these pixels. The variations between the four pixels allow us to optimize the design parameters for radiation hardness. Our experimental results exhibit increase in dark current and its non-uniformity after radiation. It is also found that Enclosed Layout Transistor (ELT) transfer gate (TX) becomes the major cause of the dark current increase. The dark current increase attributed to the shallow trench isolation (STI) around the photodiode can be mitigated by recessed-STI photodiode structure when the total dose is low. Large floating diffusion (FD) shows more immunity to the radiation-induced leakage current and random noise.","Title: Rotation of foveated image in the wavelet domain\nYear: 2004\n\nAbstract: An advantage of wavelet transform is its efficiency in rep- resenting natural images, that is, a natural image can be accurately represented by only a small number of retained wavelet coefficients. It is interesting to know whether some common image operations, e.g. rotation, can be performed very fast in wavelet domain. Preferably, the running time should depend only on the number of retained coefficients, not the size of the original image. However, it is not clear how this can be achieved. In this paper, we consider rota- tion, and images with a special structure: foveated images. Wavelet coefficients of a foveated image vanish outside an arrangement of circles. We exploit this structure to derive algorithms that accurately approximate rotation. The run- ning time is �(m) where m is the number of retained coef- ficients. Experiments show the accuracy of the approxima- tion.","Title: An amelioration Particle Swarm Optimization algorithm\nYear: 2010\n\nAbstract: A new amelioration Particle Swarm Optimization (SARPSO) based on simulated annealing (SA), asynchronously changed learning genes (ACLG) and roulette strategy was proposed because the classical Particle Swarm Optimization (PSO) algorithm was easily plunged into local minimums. SA had the ability of probability mutation in the search process, by which the search processes of PSO plunging into local minimums could be effectively avoided; ACLG could improve the ability of global search at the beginning, and it was propitious to be convergent to global optimization in the end; the roulette strategy could avoid prematurity of the algorithm. The emulation experiment results of three multi-peaking testing functions had shown the validity and practicability of the SARPSO algorithm.","Title: CRIM-FCHO: SAR Image Two-Stage Segmentation With Multifeature Ensemble\nYear: 2016\n\nAbstract: This paper investigates the synthetic aperture radar (SAR) image segmentation in terms of feature analysis and fusion and develops a new algorithm based on multifeature ensemble accordingly. This paper is characterized by two aspects. First, multiple heterogeneous features are extracted to accurately describe the objects in SAR images. These features are then integrated in the feature level and the similarity level, respectively, to avoid the mutual influences between different kinds of features and maximize the discriminability of the similarity measure between objects. Second, a two-stage algorithm consisting of a coarse merging stage and a fine classification stage is proposed. In the coarse merging stage, a context-based region iterative merging algorithm is designed to merge most of the unambiguous superpixels in image domain at a high speed. In the fine classification stage, a fuzzy clustering algorithm incorporating hybrid optimization is developed to balance the efficiency and the robustness of the algorithm by simultaneously searching heuristically in the complete high-dimension feature space and searching along the direction of the gradient steepest descent in each feature subspace. The effectiveness of the proposed method has been successfully validated on synthetic and real SAR images.","Title: Robustly building keypoint mappings with global information on multispectral images\nYear: 2015\n\nAbstract: This paper proposes an approach to robustly build keypoint mappings on multispectral images. The distinctiveness and repeatability of descriptors often decrease significantly on multispectral images and thus give unreliable keypoint mappings. To complement this decrease, global information over entire images is induced in this work to evaluate keypoint mappings. Initial keypoint mappings are established by utilizing descriptors. A pair of keypoint mappings determines a similarity transformation T, and then it is evaluated with the induced global information that is defined to be the similarity metric between the reference image and the transformed image by T. A process is utilized that iteratively considers the pairs of keypoint mappings and searches the best reference matched keypoint for every test keypoint. Experimental results show that the proposed approach can provide more reliable keypoint mappings than SIFT, ORB, FREAK, and ISS on multispectral images.","Title: Miniaturized optical neuroimaging in unrestrained animals.\nYear: 2015\n\nAbstract: The confluence of technological advances in optics, miniaturized electronic components and the availability of ever increasing and affordable computational power have ushered in a new era in functional neuroimaging, namely, an era in which neuroimaging of cortical function in unrestrained and unanesthetized rodents has become a reality. Traditional optical neuroimaging required animals to be anesthetized and restrained. This greatly limited the kinds of experiments that could be performed in vivo. Now one can assess blood flow and oxygenation changes resulting from functional activity and image functional response in disease models such as stroke and seizure, and even conduct long-term imaging of tumor physiology, all without the confounding effects of anesthetics or animal restraints. These advances are shedding new light on mammalian brain organization and function, and helping to elucidate loss of this organization or ‘dysfunction’ in a wide array of central nervous system disease models.","Title: Modeling Spatio-Temporal Extreme Events Using Graphical Models.\nYear: 2016\n\nAbstract: We propose a novel statistical model to describe spatio-temporal extreme events. The model can be used, for instance, to estimate extreme-value temporal pattern such as seasonality and trend, and further to predict the distribution of extreme events in the future. Such model usually involves thousands or even millions of variables in the spatio-temporal domain, whereas only one single observation ...","Title: Research on Automate Discovery of Deep Web Interfaces.\nYear: 2015\n\nAbstract: The main means to obtain information from Deep Web is submitting query condition through the provided query interfaces, so it is the first problem that needs to be solved for Deep Web data integration system. At present, most researchers think of query interface is merely defined within the form html tag. This paper firstly proposes the concept of interface block, then designs the interface block location method based on page and vision information, and finally takes the judgment of whether interface block is a query interface or not as the special multi-class classification problems and by applying classification algorithm combining C4.5 decision tree and SVM. The experiment adopts TEL-8 data sets of UIUC, and the findings indicate that the method in this paper get an accuracy of 97.30%, and has good feasibility and practicability.","Title: Variational Bayes Learning Of Multiscale Graphical Models\nYear: 2015\n\nAbstract: Multiscale (multisolution) graphical models have gained widespread popularity in recent years, since they enjoy rich modeling power as well as efficient inference procedures, Existing approaches to learning multiscale graphical models often leverage the framework of penalized likelihood, and therefore suffer from the issue of regularization selection. In this paper, we propose a novel method to learn multiscale graphical models from the Bayesian perspective. More specifically, the regularization parameters are treated as random variables that follow Gamma distributions, We then derive an efficient variational Bayes algorithm to learn the model, and further demonstrate the advantages of the proposed method through numerical experiments.","Title: An 8-stage time delay integration CMOS image sensor with on-chip polarization pixels\nYear: 2015\n\nAbstract: Machine vision applications involving the assistance of robots for scene mapping or object classification encounter issues when faced with smooth transparent surfaces, such as glass. Specular reflection from such surfaces saturate the image sensor pixels, restricting their vision of objects beyond the surface. The problem is aggravated by the movement of the robot, making traditional approaches unfeasible. We propose a solution that uses on-chip polarizers to limit the specular reflection and improve scene visibility while overcoming the limited SNR and motion artifacts by using a time delay integration image sensor. We have fabricated a 256×8×5 prototype sensor using a 0.18μm CIS process which achieves a DR of 52.3dB while providing an SNR improvement of 8.8dB over a single-stage linear scanner.","Title: An ontology to integrate multiple information domains in the patent system\nYear: 2011\n\nAbstract: In recent years, there has been an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous information domains making it very challenging to retrieve information across multiple domains. In this paper, we develop an ontology for the patent system to integrate information from the patent and court case domains. Through a use case erythropoietin, we demonstrate how this ontology can be used to enhance information retrieval across multiple domains.","Title: Forwarding Schemes for EM-based Wireless Nanosensor Networks in the Terahertz Band\nYear: 2015\n\nAbstract: Electromagnetic-based Wireless NanoSensor Networks (EM-WNSNs) operating in the TeraHertz (THz) band (0.1 THz--10 THz) has been in focus recently because of potential applications in nano-scale scenarios. However, one major hurdle for advancing nano-scale communications is the lack of suitable networking protocols to address current and future needs of nanonetworks. Working together with routing that finds the path from a source to destination, forwarding is a networking task of sending a packet to the next-hop along its path to the destination. While forwarding has been straightforward in traditional wired networks, forwarding schemes now play a vital role in determining wireless network performance. In this paper, we propose a channel-aware forwarding scheme and compare it against traditional forwarding schemes for wireless sensor networks. To fit the peculiarity of EM-WNSNs, the channel-aware forwarding scheme makes forwarding decision considering the frequency selective pecularities of the THz channel which are undesirable from a networking perspective. It is shown through simulation that the proposed channel-aware forwarding scheme outperforms traditional forwarding schemes in terms of the end-to-end capacity while maintaining comparable performance for delay.","Title: Variational Bayes learning of graphical models with hidden variables\nYear: 2015\n\nAbstract: Hidden variable graphical models are powerful tools to describe high-dimensional data; they capture dependencies between observed variables by introducing a suitable number of hidden variables. Present methods for learning the dependence structure of hidden variable graphical models are derived from the idea of maximizing penalized likelihood, and hence are associated with the troublesome problem of regularization selection. In this paper, we show that this problem can be successfully circumvented by treating the penalty parameters as random variables and describing the hidden variable graphical models in a Bayesian formulation. An efficient variational Bayes algorithm is further developed to adaptively learn the graphical model as well as the distribution of penalty parameters. Numerical results from both synthetic and real data show that the proposed variational Bayes method yields comparable or better performance than the stability selection based maximum penalized likelihood method, yet it requires several orders of magnitude less computational time.","Title: A time delay integration CMOS image sensor with online deblurring algorithm\nYear: 2015\n\nAbstract: This paper presents an online deblurring (ODB) algorithm for time delay integration (TDI) CMOS image sensor (CIS) used in small remote imaging systems, where image quality is degraded due to vibration caused by different factors. The ODB algorithm can detect and compensate the image shift so as to produce sharp TDI images. A 256×8-pixel prototype chip was fabricated using a 0.18μm CIS technology, which contains 8 TDI stages, column-parallel TDI accumulation and online deblurring circuits. The 4-transistor active pixel sensor (4T-APS) is applied, with the pixel size of 6.5μm×6.5μm and the fill factor of 28%.","Title: A Global-Shutter Centroiding Measurement CMOS Image Sensor With Star Region SNR Improvement for Star Trackers.\nYear: 2016\n\nAbstract: A star tracker is a critical sensor for determining and controlling the attitude of a satellite. It utilizes a complementary metal-oxide-semiconductor (CMOS)-active pixel sensor to map the star field onto the focal plane. Starlight is measured and star centroids are calculated to estimate attitude knowledge. In this paper, we present a CMOS image sensor for star centroid measurement in star tracke...","Title: An Antivibration Time-Delay Integration CMOS Image Sensor With Online Deblurring Algorithm.\nYear: 2016\n\nAbstract: This paper presents an antivibration time-delay integration (TDI) CMOS image sensor (CIS) for small remote imaging systems, introducing a hardware-implemented online deblurring (ODB) algorithm to address the image blur problems caused by vibrations. The proposed sensor has eight TDI stages, column-parallel TDI accumulating and ODB circuits. A 256×8-pixel prototype chip was fabricated using a 0.18-...","Title: Variational bayes learning of time-varying graphical models\nYear: 2016\n\nAbstract: We propose a tuning-free Bayesian approach to learn a set of sparse graphical models, in which adjacent graphs share similar structures. This model can be applied to estimating dynamic networks that evolve smoothly with regard to a covariate (e.g., time). Specifically, a novel structured spike and slab prior is constructed. This prior allows time-varying sparsity pattern by smoothing the spike probabilities across time using a Gauss-Markov chain. An efficient variational Bayes (VB) algorithm is then derived to learn the model, and is compared to related frequentist methods in the literature. We further extend the proposed mechanism to learn graphical models for multivariate time series in frequency domain. As an example, we analyze scalp electroencephalograms (EEG) recordings of patients at early stages of Alzheimer disease (AD), and quantify the loss of synchrony in comparison with control subjects.","Title: Anti-Starvation Channel Assignment With Global Conflict Set Selection in IEEE 802.11 WMNs.\nYear: 2016\n\nAbstract: Channel assignment algorithms play a critical role in the performance of IEEE 802.11 wireless mesh network by allocating channels and regulating interference between channels. In a channel assignment algorithm, the strategy used to compute a conflict set is crucial because it directly determines the allocation of channels to a given link. This paper investigates the fairness and prevention of flow starvation due to different strategies in selecting conflict sets in a channel assignment algorithm. We apply five different conflict set selection strategies to a vanilla channel assignment algorithm and compare the resulting network performance of each strategy. Our findings show that none of these conflict set selection strategies prevent flow starvation and achieve poor fairness as they only consider \\\"local channel conflict\\\" and lack the consideration of \\\"global channel conflict\\\". We propose a new conflict set selection for channel assignment algorithms called anti-starvation channel assignment (ASCA). Our proposed algorithm considers both local and global conflict to alleviate flow starvation and improves fairness by 62% (with respect to the fairness index) compared with the best result from existing conflict set selection strategies. To the best of our knowledge, the proposed ASCA is the first one to analyse channel assignment algorithms using the concept of local and global conflict sets.","Title: A Two-Step Prediction ADC Architecture for Integrated Low Power Image Sensors.\nYear: 2017\n\nAbstract: This paper presents a two-step prediction method for the design of low-power column-parallel analog-to-digital converters (ADC) in CMOS image sensors. The proposed prediction method takes advantage of the spatial likelihood of natural scenes, which shows strong correlations between neighboring pixels in the image. Based on this property, the proposed method predicts the MSBs of the selected pixel ...","Title: Control plane innovations to realize dynamic formulation of multicast sessions in inter-DC software-defined elastic optical networks.\nYear: 2017\n\nAbstract: It is known that to support the applications such as datacenter backup and migration, multicast should be supported efficiently in inter-datacenter (inter-DC) networks to carry the corresponding point-to multiple -point communications. Moreover, due to the traffic dynamics in inter-DC networks, we might have to consider the case that the multicast members can join or leave a multicast session dynamically. Therefore, in this work, we try to leverage control plane innovations to realize dynamic formulation of multicast sessions in inter-DC software-defined elastic optical networks (SD-EONS), which are equipped with multicast-incapable bandwidth-variable wavelength selective switches (MI-BV-WSS'). Here, one key issue to address is that the continuous changing of multicast group members can degrade the optimality of a multicast-tree. Hence, we propose to rearrange the multicast-trees adaptively to reduce their spectrum usage. Meanwhile, we try to minimize the frequency of rearrangements to avoid unnecessary operation complexity. Based on these considerations, we propose several multicast-tree rearrangement algorithms for updating multicast sessions dynamically with lightpath reroutings in inter DC SD-EONs. Both partial and full multicast-tree rearrangements are studied. Simulation results indicate that the proposed algorithms can rearrange the multicast-trees intelligently such that the blocking probability can be reduced effectively with the least lightpath reroutings. Next, based on these theoretical investigations, we consider how to implement the proposed algorithms in the control plane of an inter-DC SD-EON, We extend the OpenFlow (OF) protocol to support the dynamic formulation of multicast sessions and also design the functional models in the control plane elements to realize multicasttree rearrangements. Experiment results verify the effectiveness of our proposed algorithms and system design. (C) 2016 Elsevier B.V. All rights reserved.","Title: Outlier-insensitive Kalman smoothing and marginal message passing.\nYear: 2016\n\nAbstract: We propose a new approach to outlier-insensitive Kalman smoothing based on normal priors with unknown variance (NUV). In contrast to prior work, the actual computations amount essentially to iterations of a standard Kalman smoother (with few extra computations). The proposed approach is easily extended to nonlinear estimation problems by combining the outlier detection with an extended Kalman smoother. For the Kalman smoothing, we consider both a Modified Bryson-Frasier smoother and the recently proposed Backward Information Filter Forward Marginal smoother, neither of which requires matrix inversions.","Title: On-demand efficient polling for nanonetworks under dynamic IoT backhaul network conditions\nYear: 2016\n\nAbstract: Driven by the high sensing resolution provided by advanced nano technologies, Electromagnetic-based Wireless Nano Sensor Networks (EM-WNSNs) operating in the terahertz (THz) band is becoming an integral part of the Internet of Things (IoT). Data acquisition for EM-WNSNs face two challenges: the dynamic IoT backhaul bandwidth and THz channel conditions that jointly impact resource utilization efficiency. Specifically, the mismatch between the demands of the EM-WNSNs and the available bandwidth of the backhaul link reduces the bandwidth efficiency of IoT backhaul or the energy efficiency of EM-WNSNs. To address the new constraints that emerge from the EM-WNSN, an On-demand Efficient (OE) polling is proposed for the backhaul tier of EM-WNSNs which is composed of nano sinks that aggregate and transport data from nano sensors to the IoT gateway. The OE polling adjusts the packet aggregation process of nano sinks according to the up-to-date network conditions and we show that it achieves both high bandwidth efficiency for IoT backhaul and high energy efficiency for EM-WNSNs. To the best of our knowledge, OE polling is the first data acquisition scheme that connects EM-WNSNs with IoT by taking into consideration the dynamic IoT backhaul bandwidth and THz channel conditions.","Title: Opportunistic Geographic Forwarding in Wireless Sensor Networks for Critical Rare Events\nYear: 2016\n\nAbstract: Wireless sensor networks for rarely occurring critical events must maintain sensing coverage and low latency network connectivity to ensure event detection and subsequent rapid propagation of notification messages. Existing geographic forwarding algorithms have proved successful in providing energy efficient network connectivity for arbitrary topologies where sensing coverage is not guaranteed. This paper proposes a location aware algorithm for Swift Opportunistic Forwarding of Infrequent Events (SOFIE) that takes advantage of geometric properties common to sensing networks providing perfect area coverage. The algorithm is shown to deliver more rapid message propagation than two established, general purpose geographic forwarding algorithm in optimally and randomly placed networks of varied sensing node density. Further, the algorithm is shown to maintain this advantage when deployed in a coverage preserving, duty-cycled sensing network where nodes may power down whilst the network is actively forwarding event notification messages.","Title: TTL-based efficient forwarding for the backhaul tier in nanonetworks\nYear: 2017\n\nAbstract: Electromagnetic-based Wireless Nano Sensor Networks (EM-WNSNs) working in the TeraHertz (THz) band are developing fast because of the high sensing resolution that benefits a wide range of applications. In EM-WNSNs, nano sinks that aggregate data from nano sensors to the Internet of Things (IoT) gateway collectively form a backhaul tier of EM-WNSNs. Unlike the data tier composed of densely deployed nano sensors that are closely connected, the backhaul tier consisting of less dense nano sinks is highly vulnerable to the dynamic channel states of THz band that is sensitive to the surrounding humidity change. Thus, a forwarding scheme that adapts to dynamic channel states is needed to ensure both connectivity and efficiency of data transfers over the backhaul. Current channel-aware approaches are based on complex hardware support that cannot be deployed on nano devices due to the size constraints. To solve this problem, the Time-To-Live (TTL)-based Efficient Forwarding (TEFoward) with low complexity is proposed for the backhaul tier of multi-hop polling-based EM-WNSNs. In TEFoward, the functions carried by polling beacons are diversified besides data extraction. Nano sinks select forwarders and direct packets based on the duplicate counts and TTL values of polling beacons which reflect the latest topology information. Demanding lightweight resource support, TEFoward achieves high end-to-end data delivery ratio and energy efficiency.","Title: Fitness evaluation for channel assignment algorithms in IEEE 802.11 WMNs\nYear: 2017\n\nAbstract: Wireless mesh networks (WMNs) cannot utilize the full capability of these radio technologies without an effective channel assignment algorithm. Existing metrics for characterising the efficacy of channel assignment algorithms poorly reflect the goodput distribution in WMNs. In this paper, we develop a fitness evaluation algorithm that feeds back several indicators of efficacy to a channel assignment algorithm and evaluate the resulting goodput distribution. To the best of our knowledge, our algorithm is the first to evaluate the fitness of channel assignment algorithms with goodput distribution, average goodput, and fairness index. Simulation results show that our evaluation algorithm provides accurate prediction of goodput distribution, average goodput, and fairness index with errors below 8%.","Title: Energy Efficient Routing Algorithm Using Software Defining Network for WSNs via Unequal Clustering.\nYear: 2016\n\nAbstract: Clustering and multi-hop routing algorithms substantially prolong the lifetime of wireless sensor networks (WSNs). However, in multi-hop routing, the nodes near the sink are burdened with heavy relay traffic and tend to exhaust their energy very quickly. Thus, the energy hole arises. In this paper, we propose an SDN-based Unequal Clustering Routing (SDUCR) protocol for WSNs, which consists of a Centralized Unequal Clustering algorithm (CUCA) and a Connected Graph Based Minimum Energy Consumption (CGMEC) multi-hop routing algorithm. We use the centralized intelligence of Software Defined Network (SDN) to implement clustering and routing. Our CUCA is used to partition the network into clusters of unequal size based on residual energy and degree of sensor nodes. The CGMEC algorithm constructs a routing tree among cluster heads which ensures the connectivity among nodes and balances the communication cost of all nodes. Simulation results show that our SDUCR protocol balances the energy consumption among sensor nodes and achieves an obvious improvement on the network lifetime.","Title: Production Strategy With Substitution Under Cap-And-Trade Regulation\nYear: 2016\n\nAbstract: This paper researches the two products production strategy under cap and trade policies by newsboy model. The green product could be regarded as an equivalent of the regular product. The useful conclusions can be obtained: 1) The establishment of cap and trade will benefit for the improvement of manufacture performance. 2) After green technology input, the quantity of regular product will raise and the quantity of green product under cap and trade will decrease. 3) There is expectant profit that could be earned through selling extra carbon emission or buy less carbon emission from outside market after green technology input under cap and trade policy.","Title: Case-based reasoning classifier based on learning pseudo metric retrieval\nYear: 2017\n\nAbstract: A learning pseudo metric case-based reasoning classification method is proposed.A new classifier is redesigned on the basis of the traditional CBR classifier.The algorithm of LPM-CBR has some anti-interference ability and good robustness.The LPM-based retrieval method can improve the quality and learning ability of CBR. In case-based reasoning (CBR) classification systems, the similarity metrics play a key role and directly affect the system's performance. Based on our previous work on the learning pseudo metrics (LPM), we propose a case-based reasoning method for pattern classification, where the widely used Euclidean distance is replaced by the LPM to measure the closeness between the target case and each source case. The same type of case as the target case can be retrieved and the category of the target case can be defined by using the majority of reuse principle. Experimental results over some benchmark datasets and a fault diagnosis of the Tennessee-Eastman (TE) process demonstrate that the proposed reasoning techniques in this paper can effectively improve the classification accuracy, and the LPM-based retrieval method can substantially improve the quality and learning ability of CBR classifiers.","Title: Pulse Arrival Scheduling for Nanonetworks Under Limited IoT Access Bandwidth\nYear: 2017\n\nAbstract: Electromagnetic Wireless Nano Sensor Networks (EM-WNSNs) with molecule-level sensing capacity benefit a wide range of applications that demand high resolution. To accommodate the potentially high data volume, small antenna size, and limited energy capacity, the high-speed TeraHertz (THz) pulses sparsely distributed over time are adopted for communications among nano devices. For EM-WNSNs connected to the Internet of Things (IoT), matching the throughput of nanonetworks and the IoT access bandwidth is significant for resource utilization efficiency. On the one hand, high throughput from nano sensors are limited by IoT access bandwidth, which results in low energy efficiency of EM-WNSNs when traffic regulation mechanisms are applied. On the other hand, low throughput from nanonetworks under utilize the allocated access bandwidth. To enable efficient data forwarding towards the access network, the EM-WNSNs throughput must match the IoT access bandwidth. For this purpose, the Adaptive Pulse Interval Scheduling (APIS) scheme, which schedules the arrival pattern of pulses transmitted by nano sinks based on the access bandwidth, is proposed for event-based EM-WNSNs. From performance evaluation and modelling, APIS implements data forwarding with high energy efficiency for nanonetworks and high bandwidth efficiency for IoT access networks. To the best of our knowledge, APIS is the first pulse level access scheduling solution for EM-WNSNs connected to the IoT.","Title: On-Demand Probabilistic Polling for Nanonetworks Under Dynamic IoT Backhaul Network Conditions.\nYear: 2017\n\nAbstract: Driven by the high sensing resolution provided by advanced nano technologies, electromagnetic-based wireless nano sensor networks (EM-WNSNs) operating in the terahertz (THz) band is becoming an integral part of the Internet of Things (IoT). Data acquisition for EM-WNSNs faces two challenges: 1) the dynamic IoT backhaul bandwidth and 2) THz channel conditions that jointly impact resource utilizatio...","Title: Learning a fuzzy decision tree from uncertain data\nYear: 2017\n\nAbstract: Uncertainty in data exists when the value of a data item is not a precise value, but rather by an interval data with a probability distribution function, or a probability distribution of multiple values. Since there are intrinsic differences between uncertain and certain data, it is difficult to deal with uncertain data using traditional classification algorithms. Therefore, in this paper, we propose a fuzzy decision tree algorithm based on a classical ID3 algorithm, it integrates fuzzy set theory and ID3 to overcome the uncertain data classification problem. Besides, we propose a discretization algorithm that enables our proposed Fuzzy-ID3 algorithm to handle the interval data. Experimental results show that our Fuzzy-ID3 algorithm is a practical and robust solution to the problem of uncertain data classification and that it performs better than some of the existing algorithms.","Title: Self-Adaptive Gravitational Search Algorithm With a Modified Chaotic Local Search.\nYear: 2017\n\nAbstract: The gravitational search algorithm (GSA) has been proved to yield good performance in solving various optimization problems. However, it is inevitable to suffer from slow exploitation when solving complex problems. In this paper, a thorough empirical analysis of the GSA is performed, which elaborates the role of the gravitational parameter G in the optimization process of the GSA. The convergence speed and solution quality are found to be highly sensitive to the value of G. A self-adaptive mechanism is proposed to adjust the value of G automatically, aiming to maintain the balance of exploration and exploitation. To further improve the convergence speed of GSA, we also modify the classic chaotic local search and insert it into the optimization process of the GSA. Through these two techniques, the main weakness of GSA has been overcome effectively, and the obtained results of 23 benchmark functions confirm the excellent performance of the proposed method.","Title: A Comprehensive Study Of Blind And Non-Blind Deconvolution Methods Applied To Spectrum Extraction\nYear: 2017\n\nAbstract: Spectrum extraction which is applied to extract one-dimensional (1D) astronomical spectroscopy from two-dimensional (2D) multi-fiber spectrum images plays a key role in data processing of 2D optical fiber spectrum. In this paper, we have given a detailed comparison of spectrum extraction methods between the blind deconvolution and the non-blind deconvolution to find out their specialities. The simulated arc spectrum data is used in Comparative experiments. The results show that the blind deconvolution is better than the non-blind deconvolution not only at spectrum extraction result but also remarkably at signal noise ratio (SNR).","Title: Linear-Complexity Stochastic Variational Bayes Inference For Slam\nYear: 2017\n\nAbstract: The simultaneous localization and mapping (SLAM) problem is concerned with using sensor data to build an environmental map, while also localizing an autonomous agent within this map. Two approaches are currently prevalent (Bayesian filtering and graph-based optimization), however these both involve approximations and have the potential to be improved. In this paper, we propose novel high-performance SLAM algorithms derived from variational Bayes inference. By using mean-field type approximations, the resulting computational complexity is linear. We also add an empirical Bayes assumption to improve the flexibility of the inference. Experiments are conducted on both synthetic data and real RGB-D images. The proposed approach achieves 42% average error reduction in all scenarios on synthetic data, and 26% average error reduction on real images (with respect to two other baseline algorithms).","Title: Noncontact Human-Machine Interface With Planar Probing Coils in a Differential Sensing Architecture.\nYear: 2018\n\nAbstract: This paper presents a noncontact human-machine interface which is capable of sensing and indicating the position of a human hand that is approaching a probing coil. High sensitivity is achieved by utilizing a structure including two oscillators and a mixer to compare and extract the electromagnetic shift between two probing coils. The probing coils chosen in this system have a planar structure and...","Title: An Incremental Dual nu-Support Vector Regression Algorithm.\nYear: 2018\n\nAbstract: Support vector regression (SVR) has been a hot research topic for several years as it is an effective regression learning algorithm. Early studies on SVR mostly focus on solving large-scale problems. Nowadays, an increasing number of researchers are focusing on incremental SVR algorithms. However, these incremental SVR algorithms cannot handle uncertain data, which are very common in real life because the data in the training example must be precise. Therefore, to handle the incremental regression problem with uncertain data, an incremental dual nu-support vector regression algorithm (dual-v-SVR) is proposed. In the algorithm, a dual-v-SVR formulation is designed to handle the uncertain data at first, then we design two special adjustments to enable the dual-v-SVR model to learn incrementally: incremental adjustment and decremental adjustment. Finally, the experiment results demonstrate that the incremental dual-v-SVR algorithm is an efficient incremental algorithm which is not only capable of solving the incremental regression problem with uncertain data, it is also faster than batch or other incremental SVR algorithms.","Title: TTL-Based Efficient Forwarding for Nanonetworks With Multiple Coordinated IoT Gateways.\nYear: 2018\n\nAbstract: Electromagnetic-based wireless nanosensor networks (EM-WNSNs) working in the terahertz (THz) band are developing fast because of the high sensing resolution that benefits a wide range of applications. In EM-WNSNs, nano-sinks that aggregate data from nanosensors to the Internet of Things (IoT) gateway collectively form a backhaul tier of EM-WNSNs. Unlike the data tier composed of densely deployed n...","Title: A 16 MHz, 59.2 ppm/°C CMOS DLL-Assisted VCO with Improved Frequency Stability Towards Single Chip Wireless IOT\nYear: 2016\n\nAbstract: A 16 MHz, highly stable voltage controlled oscillator (VCO) is reported in this paper. The proposed VCO consists of three cross-coupled RC stages, and is fully compatible with standard CMOS process. A positively biased PN junction with negative temperature coefficient is incorporated in the design to compensate frequency drift. In addition, a delay locked loop (DLL) directly following the VCO is utilized to further improve the output stability caused by temperature variations. The designed circuit was implemented using CMOS 0.18 mu m technology, and was validated through experiments. Measurement results show that the DLL-assisted VCO output variation across the 25 similar to 120 A degrees C temperature range is less than 0.56 %, corresponding to 59.2 ppm/A degrees C. It also shows that the output standard deviation of the DLL-assisted VCO is only 6.816 KHz, similar to 16.6 % better compared with the same VCO without DLL's assistance.","Title: Multi-Gateway Polling for Nanonetworks under Dynamic IoT Backhaul Bandwidth\nYear: 2018\n\nAbstract: As an emerging part of the Internet of Things (IoT), Electromagnetic-based Wireless NanoSensor Networks (EM-WNSNs) working in the TeraHertz (THz) band are envisaged to enable applications that demand high sensing resolution. For the high-speed nanonetworks deployed for time critical applications, the limited IoT backhaul bandwidth of the existing infrastructure becomes the bottleneck that deteriorates resource utilization efficiency. On the one hand, the bandwidth demand exceeding the supply results in unnecessary energy consumption on nano-devices due to the overdue data discarded. On the other hand, the excess supply of bandwidth reduces the bandwidth efficiency. To address this problem, the On-demand Efficient (OE) polling and On-demand Probabilistic (OP) polling were proposed. Nevertheless, the existing solutions only apply to the single-gateway scenario whereas deploying multiple gateways is required for achieving high data completeness and energy efficiency. Therefore, in this paper, we propose the Multi-gateway Probabilistic (MP) polling for the multi-gateway EMWNSNs. To achieve high bandwidth efficiency, in MP polling, one master gateway is selected for OP polling with the aggregated bandwidth that reduces the probabilistic uncertainty. Next, all gateways probabilistically receive packets using the bandwidth-based receiving windows. To the best of our knowledge, MP Polling is the first polling solution designed for the multi gateway EM-WNSNs under dynamic backhaul bandwidth.","Title: Study on Security Technology of Internet of Things Based on Network Coding\nYear: 2018\n\nAbstract: Along with the continuous progress of the information technology, Internet of Things is the inevitable way for realizing the fusion of communication and traditional network technology. Network coding, an important breakthrough in the field of communication, has many applied advantages in information network. This article analyses the eavesdropping problem of Internet of Things and presents an information secure network coding scheme against the eavesdropping adversaries. We show that, if the number of links the adversaries can eavesdrop on is less than the max-flow of a network, the proposed coding scheme not only `achieves the prefect information secure condition but also the max-flow of the network.","Title: A CMOS Time-to-Digital Converter for Real-Time Optical Time-of-Flight Sensing System.\nYear: 2018\n\nAbstract: The TOF method is the most popular and efficient way to extract depth information in an optical sensing system, and TDC is generally used to measure the round-trip delay. In this article, a TDC with ~40 ps measurement resolution and very large linear dynamic range is proposed for optical sensing applications. Referenced to a single 100 MHz clock, the TDC incorporates a DLL and a VDL loop to automa...","Title: Design and Characteristic Analysis of Cross-Capacitance Fuel-Level Sensor.\nYear: 2018\n\nAbstract: A cross-capacitance liquid level sensor is based on the principle of cross capacitance. This study designed a new single-tube cross-capacitance fuel-level sensor. The fuel-level measurement model is established for a single-tube cross-capacitive sensor, and the relationship between the measured liquid level and sensor output capacitance is derived. The characteristics of the sensor were tested experimentally. The experimental results demonstrate that the linearity error of the liquid-level sensor of the single-tube calculation for the spacecraft is +/- 0.48%, the repeatability error is +/- 0.47%, and the hysteresis error is +/- 0.68%. The cross-capacitive fuel-level sensor developed in this study can be used in the fuel tank of spacecrafts owing to its low weight and high precision.","Title: Detecting and Segmenting White Blood Cells in Microscopy Images of Thin Blood Smears\nYear: 2017\n\nAbstract: A malarial infection is diagnosed and monitored by screening microscope images of blood smears for parasite-infected red blood cells. Millions of blood slides are manually screened for parasites every year, which is a tedious and error-prone process, and which largely depends on the expertise of the microscopists. We have developed a software to perform this task on a smartphone, using machine learning and image analysis methods for counting infected red blood cells automatically. The method we implemented first needs to detect and segment red blood cells. However, the presence of white blood cells (WBCs) contaminates the red blood cell detection and segmentation process because WBCs can be miscounted as red blood cells by automatic cell detection methods. As a result, a preprocessing step for WBC elimination is essential. Our paper proposes a novel method for white blood cell segmentation in microscopic images of blood smears. First, a range filtering algorithm is used to specify the location of white blood cells in the image following a Chan- Vese level-set algorithm to estimate the boundaries of each white blood cell present in the image. The proposed segmentation algorithm is systematically tested on a database of more than 1300 thin blood smear images exhibiting approximately 1350 WBCs. We evaluate the performance of the proposed method for the two WBC detection and WBC segmentation steps by comparing the annotations provided by a human expert with the results produced by the proposed algorithm. Our detection technique achieves a 96.37 % overall precision, 98.37 % recall, and 97.36 % Fl-score. The proposed segmentation method grants an overall 82.28 % Jaccard Similarity Index. These results demonstrate that our approach allows us to filter out WBCs, which significantly improves the precision of the cell counts for malaria diagnosis.","Title: A Unified Smart Chinese Medicine Framework for Healthcare and Medical Services.\nYear: 2021\n\nAbstract: Smart Chinese medicine has emerged to contribute to the evolution of healthcare and medical services by applying machine learning together with advanced computing techniques like cloud computing to computer-aided diagnosis and treatment in the health engineering and informatics. Specifically, smart Chinese medicine is considered to have the potential to treat difficult and complicated diseases suc...","Title: Parallel Parametric Linear Programming Solving, And Application To Polyhedral Computations\nYear: 2019\n\nAbstract: Parametric linear programming is central in polyhedral computations and in certain control applications. We propose a task-based scheme for parallelizing it, with quasi-linear speedup over large problems.","Title: Weighted total least-squares joint adjustment with weight correction factors\nYear: 2019\n\nAbstract: A joint adjustment involves integrating different types of geodetic datasets, or multiple datasets of the same data type, into a single adjustment. This paper applies the weighted total least-squares (WTLS) principle to joint adjustment problems and proposes an iterative algorithm for WTLS joint (WTLS-J) adjustment with weight correction factors. Weight correction factors are used to rescale the weight matrix of each dataset while using the Helmert variance component estimation (VCE) method to estimate the variance components, since the variance components in the stochastic model are unknown. An affine transformation example is illustrated to verify the practical benefit and the relative computational efficiency of the proposed algorithm. It is shown that the proposed algorithm obtains the same parameter estimates as the Amiri-Simkooei algorithm in our example; however, the proposed algorithm has its own computational advantages, especially when the number of data points is large.","Title: Weighted total least-squares joint adjustment with weight correction factors\nYear: 2019\n\nAbstract: A joint adjustment involves integrating different types of geodetic datasets, or multiple datasets of the same data type, into a single adjustment. This paper applies the weighted total least-squares (WTLS) principle to joint adjustment problems and proposes an iterative algorithm for WTLS joint (WTLS-J) adjustment with weight correction factors. Weight correction factors are used to rescale the weight matrix of each dataset while using the Helmert variance component estimation (VCE) method to estimate the variance components, since the variance components in the stochastic model are unknown. An affine transformation example is illustrated to verify the practical benefit and the relative computational efficiency of the proposed algorithm. It is shown that the proposed algorithm obtains the same parameter estimates as the Amiri-Simkooei algorithm in our example; however, the proposed algorithm has its own computational advantages, especially when the number of data points is large.","Title: Deep reinforcement learning with its application for lung cancer detection in medical Internet of Things\nYear: 2019\n\nAbstract: Recently, deep reinforcement learning has achieved great success by integrating deep learning models into reinforcement learning algorithms in various applications such as computer games and robots. Specially, it is promising for computer-aided diagnosis and treatment to combine deep reinforcement learning with medical big data generated and collected from medical Internet of Things. In this paper, we focus on the potential of the deep reinforcement learning for lung cancer detection as many people are suffering from the lung tumor and about 1.8 million patients died from lung cancer in 2018. Early detection and diagnosis of lung tumor can significantly improve the treatment effect and prolong survival. In this work, we present several representative deep reinforcement learning models that are potential to use for lung cancer detection. Furthermore, we summarize the common types of lung cancer and the main characteristics of each type. Finally, we point out the open challenges and possible future research directions of applying deep reinforcement learning to lung cancer detection, which is expected to promote the evolution of smart medicine with medical Internet of Things.","Title: Deep Learning Models For Diagnosing Spleen And Stomach Diseases In Smart Chinese Medicine With Cloud Computing\nYear: 2021\n\nAbstract: Cloud computing is significantly contributing to the development of smart Chinese medicine. The diagnosis and treatment of spleen and stomach diseases has been arousing great interest in smart Chinese medicine with cloud computing since many persons are suffering from spleen and stomach diseases. Currently, spleen and stomach diseases present some new characteristics with the dramatic changes in natural climate, social environment, and human living habits. Recently, deep learning, together with cloud computing techniques, has successfully used in medical image analysis and therefore it is the most promising model for diagnosing spleen and stomach disease in smart Chinese medicine. In this paper, we present a survey on deep learning models in medical image analysis for computer-aided diagnosis in modern medicine. Afterwards, we summarize the syndrome types of spleen and stomach diseases and furthermore analyze the causes and pathogenesis for each syndrome. Finally, we discuss the open challenges and research directions of deep learning models applicable to the computer-aided diagnosis of spleen and stomach diseases, which is expected to contribute to the development of smart Chinese medicine with cloud computing.","Title: Mathematical modeling of yard template regeneration for multiple container terminals\nYear: 2019\n\nAbstract: As a tactical-level plan, the yard template determines the space allocation in a container terminal yard for all the arriving shipping liners. Generally speaking, the yard template will not change and it may last a matter of years. However, it has to be changed to response to the alteration of shipping liner. This paper investigates the problem of yard template regeneration for container port, which contains multiple container terminals. Firstly, the concept of yard template regeneration as well as the main influencing factors is proposed. Secondly, a multiple-objective mixed integer programming model is formulated which fully considering the minimum transportation cost, minimum template disturbance and maximum space utilization. Moreover, a case study is conducted to intuitively illustrate the regeneration problem of yard template. Finally, performance analysis and sensitivity analysis are performed to validate the effectiveness of the model.","Title: Efficient Stochastic Subgradient Descent Algorithms For High-Dimensional Semi-Sparse Graphical Model Selection\nYear: 2019\n\nAbstract: We consider the structure learning problem of Gaussian graphical models when the underlying graph is semi-sparse. More specifically, we assume that the number of edges in the graph grows quadratically with the dimension P. Similar to the case of sparse graphs, the problem is formulated as maximizing the data log-likelihood with an l(1) norm penalty on the precision matrix (the inverse covariance matrix) that promotes sparsity. We notice that the time complexity of all existing methods is at least O(P-3) under the scenario of semi-sparse graphs, thus severely hindering their applications to high-dimensional data. By contrast, the time complexity of the proposed method is only O(P-2) with the help of stochastic gradients. We prove the convergence of the proposed algorithm. Numerical results show that the computational time of the proposed method is shorter than that of the state-of-the-art methods when the graph is semi-sparse.","Title: The Verified Polyhedron Library: an Overview\nYear: 2018\n\nAbstract: The Verified Polyhedra Library operates upon a constraint-only representation of convex polyhedra and provides all common operations (image, pre-image, projection, convex hull, widening, inclusion and equality tests. . . ). Optionally, the soundness of the results is checked by a layer certified in Coq.","Title: A Bayesian Method For Dynamic Origin-Destination Demand Estimation Synthesizing Multiple Sources Of Data\nYear: 2021\n\nAbstract: In this paper a Bayesian method is proposed to estimate dynamic origin-destination (O-D) demand. The proposed method can synthesize multiple sources of data collected by various sensors, including link counts, turning movements at intersections, flows, and travel times on partial paths. Time-dependent demand for each O-D pair at each departure time is assumed to satisfy the normal distribution. The connections among multiple sources of field data and O-D demands for all departure times are established by their variance-covariance matrices. Given the prior distribution of dynamic O-D demands, the posterior distribution is developed by updating the traffic count information. Then, based on the posterior distribution, both point estimation and the corresponding confidence intervals of O-D demand variables are estimated. Further, a stepwise algorithm that can avoid matrix inversion, in which traffic counts are updated one by one, is proposed. Finally, a numerical example is conducted on Nguyen-Dupuis network to demonstrate the effectiveness of the proposed Bayesian method and solution algorithm. Results show that the total O-D variance is decreasing with each added traffic count, implying that updating traffic counts reduces O-D demand uncertainty. Using the proposed method, both total error and source-specific errors between estimated and observed traffic counts decrease by iteration. Specifically, using 52 multiple sources of traffic counts, the relative errors of almost 50% traffic counts are less than 5%, the relative errors of 85% traffic counts are less than 10%, the total error between the estimated and \"true\" O-D demands is relatively small, and the O-D demand estimation accuracy can be improved by using more traffic counts. It concludes that the proposed Bayesian method can effectively synthesize multiple sources of data and estimate dynamic O-D demands with fine accuracy.","Title: Research on economic benefits of multi-city logistics development based on data-driven analysis\nYear: 2021\n\nAbstract: This study aims to measure the logistics economic efficiency of major first-tier cities in China and propose the interactive development plan of the green logistics industry based on the division of the urban agglomeration. In this study, the evaluation system for the logistics input and economic output of urban agglomerations is firstly established based on data-driven analytics, and a green logistics economic efficiency model using the dataset from 2008 to 2017 is constructed to estimate the input–output efficiency, development trend, and spatial differentiation of urban agglomerations comprehensively. Finally, the Shapley value method is adopted to obtain the specific distribution plan of logistics investment. The results show that the logistics economic efficiency of the 9 major urban agglomerations is all greater than 1 under the constant returns-to-scale (CRS) hypothesis while the average logistics economic efficiency of Pearl River Delta region, Chengdu-Chongqing region, and Shandong Peninsula region is significantly less than 1 under the medium returns-to-scale (MRS) hypothesis. The comprehensive input–output efficiency of five out of 9 major Chinese urban agglomerations showed a downward trend, with the highest declining rate of 5.9% in the Yangtze River Delta urban agglomeration. The urban agglomeration with the highest increase rate in input–output efficiency from 2013 to 2017 is the Chengdu-Chongqing region, which reached 3.97%.","Title: Laser Induced Graphene Patterns On A Thin Polyimide Film Via A Cooling Plate\nYear: 2021\n\nAbstract: Laser induced graphene technology on a polyimide (PI) film substrate for supercapacitors, flexible sensors and heaters, has been a hot topic due to its fast fabrication speed and 3D controllable microstructure formation. However, the thin PI film will suffer burnthrough of the film under the required high energy density to form graphene. Herein, we introduced an auxiliary cooling semiconductor plate beneath the PI substrate to decrease the temperature of the substrate to reduce the burnt thickness. Experiment results showed that the burnt thickness will decrease to about 33.39 mu m for -2 degrees C on the thin film with thickness about 12 mu m and the value of resistance can still be kept at 8.33 k Omega. The effects of the scanning speed and power on the size of the wire also discussed. Therefore, such method may open a way to fabricate graphene patterns on thin films with thickness less than a few micrometers, which will play an important role in applications including electronic skins and multi-layer flexible plastic circuits.","Title: Salient Region Guided Blind Image Sharpness Assessment\nYear: 2021\n\nAbstract: Salient regions provide important cues for scene understanding to the human vision system. However, whether the detected salient regions are helpful in image blur estimation is unknown. In this study, a salient region guided blind image sharpness assessment (BISA) framework is proposed, and the effect of the detected salient regions on the BISA performance is investigated. Specifically, three salient region detection (SRD) methods and ten BISA models are jointly explored, during which the output saliency maps from SRD methods are re-organized as the input of BISA models. Consequently, the change in BISA metric values can be quantified and then directly related to the difference in BISA model inputs. Finally, experiments are conducted on three Gaussian blurring image databases, and the BISA prediction performance is evaluated. The comparison results indicate that salient region input can help achieve a close and sometimes superior performance to a BISA model over the whole image input. When using the center region input as the baseline, the detected salient regions from the saliency optimization from robust background detection (SORBD) method lead to consistently better score prediction, regardless of the BISA model. Based on the proposed hybrid framework, this study reveals that saliency detection benefits image blur estimation, while how to properly incorporate SRD methods and BISA models to improve the score prediction will be explored in our future work.","Title: Trajectory Planning for Collaborative Transportation by Tethered Multi-UAVs\nYear: 2021\n\nAbstract: Collaborative transportation has been widely studied due to its high efficiency, and interesting research problems., specifically in trajectory planning. In this paper, a new trajectory planning scheme for collaborative transportation by tethered multi-UAVs is proposed to avoid obstacles. Firstly, the dynamics and configuration of the system is analyzed to derive the tethered force acting on each UAV, and define the angle between the rope and the vertical direction is calculated. Then the kinodynamic path search method is used to search an initial trajectory of the payload, and the initial trajectory of each UAV is solved. Finally, nonlinear optimization is used to optimize the trajectory of each UAV and the payload to achieve the effect of obstacle avoidance. Both numerical simulations and practical experiments are completed to verify the feasibility and effectiveness of the proposed planning scheme.","Title: Progressive Diversified Augmentation for General Robustness of DNNs: A Unified Approach\nYear: 2021\n\nAbstract: Adversarial images are imperceptible perturbations to mislead deep neural networks (DNNs), which have attracted great attention in recent years. Although several defense strategies achieved encouraging robustness against adversarial samples, most of them still failed to consider the robustness on common corruptions (e.g. noise, blur, and weather/digital effects). To address this problem, we propose a simple yet effective method, named Progressive Diversified Augmentation (PDA), which improves the robustness of DNNs by progressively injecting diverse adversarial noises during training. In other words, DNNs trained with PDA achieve better general robustness against both adversarial attacks and common corruptions than other strategies. In addition, PDA also enjoys the advantages of spending less training time and keeping high standard accuracy on clean examples. Further, we theoretically prove that PDA can control the perturbation bound and guarantee better robustness. Extensive results on CIFAR-10, SVHN, ImageNet, CIFAR-10-C and ImageNet-C have demonstrated that PDA comprehensively outperforms its counterparts on the robustness against adversarial examples and common corruptions as well as clean images. More experiments on the frequency-based perturbations and visualized gradients further prove that PDA achieves general robustness and is more aligned with the human visual system.","Title: How Does Social Behavior Affect Your Password?\nYear: 2021\n\nAbstract: A password is an important method of identity authentication, so there are endless research attempts on passwords, but most of them are based on different languages and technologies. As far as we know, no one has studied the influence of one's social behavior (e.g., religious belief) on passwords. Based on this, we first study the influence of religion on the generation of user passwords. Taking C...","Title: Further studies on numerical instabilities of Godunov-type schemes for strong shocks\nYear: 2021\n\nAbstract: In this paper, continuous research is undertaken to explore the underlying mechanism of numerical shock instabilities of Godunov-type schemes for strong shocks. By conducting dissipation analysis of Godunov-type schemes and a sequence of numerical experiments, we are able to clarify that the instability may be attributed to insufficient entropy production inside the numerical shock structure. As a result, a general entropy-control technique for improving the robustness of various Godunov-type schemes at strong shocks is developed. It plays a part in guaranteeing that enough entropy is produced inside the numerical shock structure. Furthermore, such a modified approach does not introduce any additional numerical dissipation on linear degenerate waves to suppress the shock instability. Numerical results that are obtained for various test cases indicate that the proposed methods have a good performance in terms of accuracy and robustness.","Title: An Online Robust Support Vector Regression for Data Streams\nYear: 2022\n\nAbstract: Since support vector regression (SVR) is a flexible regression algorithm, its computational complexity does not depend on the dimensionality of the input space, and it has excellent generalization capability. However, a central assumption with SVRs is that all the required data is available at the time of construction, which means these algorithms cannot be used with data streams. Incremental SVR ...","Title: Distributed cooperative guidance law for multiple missiles with input delay and topology switching\nYear: 2021\n\nAbstract: This paper considers the simultaneous attack of a stationary target by multiple missiles. A novel fixed-time distributed guidance law based on the proportional navigation (PN) guidance law is designed by integrating a consistent control technique into the guidance strategy. This guarantees that the time-to-go of the missile becomes consistent. The guidance law adopts a discrete design, and a compensation item driven by normal acceleration is added to tangential acceleration. This eliminates the potential singularity problem when the heading angle is zero before the consistency is obtained, and thus the multiple missile system still converges in fixed time. In addition, the proposed guidance law can be applied to both undirected and directed graphs. Furthermore, two improved guidance laws are proposed to improve the robustness of the system against adverse effects caused by input delays and topology switching failures and to provide a theoretical proof. Finally, a simulation is used to verify the performance of the distributed guidance law and its robustness against the above failures.","Title: Identifying Drug-Resistant Tuberculosis in Chest Radiographs: Evaluation of CNN Architectures and Training Strategies\nYear: 2021\n\nAbstract: Tuberculosis (TB) is a serious infectious disease that mainly affects the lungs. Drug resistance to the disease makes it more challenging to control. Early diagnosis of drug resistance can help with decision making resulting in appropriate and successful treatment. Chest X-rays (CXRs) have been pivotal to identifying tuberculosis and are widely available. In this work, we utilize CXRs to distinguish between drug-resistant and drug-sensitive tuberculosis. We incorporate Convolutional Neural Network (CNN) based models to discriminate the two types of TB, and employ standard and deep learning based data augmentation methods to improve the classification. Using labeled data from NIAID TB Portals and additional non-labeled sources, we were able to achieve an Area Under the ROC Curve (AUC) of up to 85% using a pretrained InceptionV3 network.","Title: Secure typing via BCI system with encrypted feedback\nYear: 2021\n\nAbstract: Information transmission security is an important issue in many scenarios such as password input. Traditional approaches such as typing or voice input are prone to peep, leading to a risk of information leakage. Brain computer interface (BCI) can read information directly from the brain, which is confidential inherently, thus it may be an ideal way for secure information input. This paper proposes a novel BCI-based secure input approach with encrypted feedback. The encrypted feedback is specially designed to notify users and confuse peepers at the same time. We give the theoretical guarantee of accuracy and evaluate the system with both simulation and experiments. The results show that our method can transmit messages effectively.","Title: CvT-ASSD: Convolutional vision-Transformer Based Attentive Single Shot MultiBox Detector\nYear: 2021\n\nAbstract: Due to the success of Bidirectional Encoder Representations from Transformers (BERT) in natural language process (NLP), the multi-head attention transformer has been more and more prevalent in computer-vision researches (CV). However, it still remains a challenge for researchers to put forward complex tasks such as vision detection and semantic segmentation. Although multiple Transformer-Based architectures like DETR and ViT-FRCNN have been proposed to complete object detection task, they inevitably decreases discrimination accuracy and brings down computational efficiency caused by the enormous learning parameters and heavy computational complexity incurred by the traditional self-attention operation. In order to alleviate these issues, we present a novel object detection architecture, named Convolutional vision Transformer-Based Attentive Single Shot MultiBox Detector (CvT-ASSD), that built on the top of Convolutional vision Transormer (CvT) with the efficient Attentive Single Shot MultiBox Detector (ASSD). We provide comprehensive empirical evidence showing that our model CvT-ASSD can leads to good system efficiency and performance while being pretrained on large-scale detection datasets such as PASCAL VOC and MS COCO. Code has been released on public github repository at https://github.com/albert-jin/CvT-ASSD.","Title: Efficient Variational Bayes Learning of Graphical Models With Smooth Structural Changes\nYear: 2023\n\nAbstract: Estimating a sequence of dynamic undirected graphical models, in which adjacent graphs share similar structures, is of paramount importance in various social, financial, biological, and engineering systems, since the evolution of such networks can be utilized for example to spot trends, detect anomalies, predict vulnerability, and evaluate the impact of interventions. Existing methods for learning dynamic graphical models require the tuning parameters that control the graph sparsity and the temporal smoothness to be selected via brute-force grid search. Furthermore, these methods are computationally burdensome with time complexity \n<inline-formula><tex-math notation=\"LaTeX\">$\\mathcal {O}(NP^3)$</tex-math></inline-formula>\n for \n<inline-formula><tex-math notation=\"LaTeX\">$P$</tex-math></inline-formula>\n variables and \n<inline-formula><tex-math notation=\"LaTeX\">$N$</tex-math></inline-formula>\n time points. As a remedy, we propose a low-complexity tuning-free Bayesian approach, named BASS. Specifically, we impose temporally dependent spike and slab priors on the graphs such that they are sparse and varying smoothly across time. An efficient variational inference algorithm based on natural gradients is then derived to learn the graph structures from the data in an automatic manner. Owing to the pseudo-likelihood and the mean-field approximation, the time complexity of BASS is only \n<inline-formula><tex-math notation=\"LaTeX\">$\\mathcal {O}(NP^2)$</tex-math></inline-formula>\n. To cope with the local maxima problem of variational inference, we resort to simulated annealing and propose a method based on bootstrapping of the observations to generate the annealing noise. We provide numerical evidence that BASS outperforms existing methods on synthetic data in terms of structure estimation, while being more efficient especially when the dimension \n<inline-formula><tex-math notation=\"LaTeX\">$P$</tex-math></inline-formula>\n becomes high. We further apply the approach to the stock return data of 78 banks from 2005 to 2013 and find that the number of edges in the financial network as a function of time contains three peaks, in coincidence with the 2008 global financial crisis and the two subsequent European debt crisis. On the other hand, by identifying the frequency-domain resemblance to the time-varying graphical models, we show that BASS can be extended to learning frequency-varying inverse spectral density matrices, and further yields graphical models for multivariate stationary time series. As an illustration, we analyze scalp EEG signals of patients at the early stages of Alzheimer’s disease (AD) and show that the brain networks extracted by BASS can better distinguish between the patients and the healthy controls.","Title: Entity Relation Fusion for Real-Time One-Stage Referring Expression Comprehension\nYear: 2021\n\nAbstract: ABSTRACTReferring Expression Comprehension (REC) is the task of grounding object which is referred by the language expression. Previous one-stage REC methods usually use one single language feature vector to represent the whole query for grounding and no reasoning between different objects is performed despite the rich relation cues of objects contained in the language expression, which depresses their grounding accuracy. Additionally, these methods mostly use the feature pyramid networks for multi-scale visual object feature extraction but ground on different feature layers separately, neglecting the connections between objects with different scales. To address these problems, we propose a novel one-stage REC method, i.e. the Entity Relation Fusion Network (ERFN) to locate referred object by relation guided reasoning on different objects. In ERFN, instead of grounding objects at each layer separately, we propose a Language Guided Multi-Scale Fusion (LGMSF) model to utilize language to guide the fusion of representations of objects with different scales into one feature map.For modeling connections between different objects, we design a Relation Guided Feature Fusion (RGFF) model that extracts entities in the language expression to enhance the referred entity feature in the visual object feature map, and further extracts relations to guide object feature fusion based on the self-attention mechanism. Experimental results show that our method is competitive with the state-of-the-art one-stage and two-stage REC methods, and can also keep inferring in real time.","Title: Nonlinear Noise Cleaning in Gravitational-Wave Detectors With Convolutional Neural Networks.\nYear: 2022\n\nAbstract: Currently, the sub-60 Hz sensitivity of gravitational-wave (GW) detectors like Advanced LIGO (aLIGO) is limited by the control noises from auxiliary degrees of freedom which nonlinearly couple to the main GW readout. One promising way to tackle this challenge is to perform nonlinear noise mitigation using convolutional neural networks (CNNs), which we examine in detail in this study. In many cases, the noise coupling is bilinear and can be viewed as a few fast channels' outputs modulated by some slow channels. We show that we can utilize this knowledge of the physical system and adopt an explicit \"slow×fast\" structure in the design of the CNN to enhance its performance of noise subtraction. We then examine the requirements in the signal-to-noise ratio (SNR) in both the target channel (i.e., the main GW readout) and in the auxiliary sensors in order to reduce the noise by at least a factor of a few. In the case of limited SNR in the target channel, we further demonstrate that the CNN can still reach a good performance if we use curriculum learning techniques, which in reality can be achieved by combining data from quiet times and those from periods with active noise injections.","Title: Pyraformer: Low-Complexity Pyramidal Attention for Long-Range Time Series Modeling and Forecasting\nYear: 2022\n\nAbstract: Accurate prediction of the future given the past based on time series data is of paramount importance, since it opens the door for decision making and risk management ahead of time. In practice, the challenge is to build a flexible but parsimonious model that can capture a wide range of temporal dependencies. In this paper, we propose Pyraformer by exploring the multiresolution representation of the time series. Specifically, we introduce the pyramidal attention module (PAM) in which the inter-scale tree structure summarizes features at different resolutions and the intra-scale neighboring connections model the temporal dependencies of different ranges. Under mild conditions, the maximum length of the signal traversing path in Pyraformer is a constant (i.e., $\\mathcal O(1)$) with regard to the sequence length $L$, while its time and space complexity scale linearly with $L$. Extensive numerical results show that Pyraformer typically achieves the highest prediction accuracy in both single-step and long-range forecasting tasks with the least amount of time and memory consumption, especially when the sequence is long.","Title: Quantitative Analysis of Structural Parameters Importance of Helical Temperature Microfiber Sensor by Artificial Neural Network\nYear: 2021\n\nAbstract: With the assistance of the evaluation algorithms based on the well-performed backpropagation neural network (BPNN), we quantitatively analyze the importance of the structural parameters of the supported helical microfiber (HMF) temperature sensor. The relative output intensities of HMF sensor at different temperatures are predicted by the BPNN with the HMF's structural parameters as the input variables. The best-forecasted performance is obtained by the BPNN with one hidden layer of ten neurons. Compared with the actual values, the root-mean-square error (RMSE) and the correlation coefficient of the predicted values are 9.7 x 10(-3) dB and 99.84%, respectively. Based on the BPNN with precise prediction, the backward stepwise elimination and the holdback input randomization methods are used to quantitatively discuss the influence of the structural parameters on the output intensity of the HMF. The relative importance from high to low is the helical length (similar to 38%), microfiber diameter (similar to 27%), helical angle (similar to 25%), and cone angle (similar to 10%). The importance of four geometric parameters obtained by the two methods is ranked the same. Quantitative analysis of structural parameters relying on the well-predicted BPNN can give basic information on the structural characteristics of the HMF sensor, which helps to optimize the structure design of the optical sensors based on micro/nanofiber and provides a powerful guarantee for its practical application.","Title: Remote Sensing Image Land Classification Based on Deep Learning\nYear: 2021\n\nAbstract: Aiming at the problems of high-resolution remote sensing images with many features and low classification accuracy using a single feature description, a remote sensing image land classification model based on deep learning from the perspective of ecological resource utilization is proposed. Firstly, the remote sensing image obtained by Gaofen-1 satellite is preprocessed, including multispectral data and panchromatic data. Then, the color, texture, shape, and local features are extracted from the image data, and the feature-level image fusion method is used to associate these features to realize the fusion of remote sensing image features. Finally, the fused image features are input into the trained depth belief network (DBN) for processing, and the land type is obtained by the Softmax classifier. Based on the Keras and TensorFlow platform, the experimental analysis of the proposed model shows that it can clearly classify all land types, and the overall accuracy, F1 value, and reasoning time of the classification results are 97.86%, 87.25%, and 128 ms, respectively, which are better than other comparative models.","Title: Underground Object Classification Using Deep 3-D Convolutional Networks and Multiple Mirror Encoding for GPR Data\nYear: 2022\n\nAbstract: Ground-penetrating radar (GPR) is an effective tool for underground object detection, but its data interpretation remains a great challenge. In this letter, we propose a novel underground object classification algorithm using deep 3-D convolutional networks (C3D) and multiple mirror encoding (MME) for 3-D GPR data. Although deep learning technique has been applied to interpret the GPR data, most of the existing methods are based on GPR B-scans and have a relatively low accuracy since the reflections from various subsurface targets present similar hyperbolic patterns in B-scans. To improve the classification accuracy, we use 3-D GPR data as training data for C3D to capture the spatio-temporal features between parallel B-scans. Since 3-D GPR data including single object has different sizes in consideration of actual sizes of objects, they are rearranged by the MME method to enhance spatio-temporal features, as well as to satisfy the requirement of the network input. Experimental results demonstrate that the proposed method outperforms the state-of-the-art B-scan-based methods.","Title: Semi-Supervised Cross-Subject Emotion Recognition Based on Stacked Denoising Autoencoder Architecture Using a Fusion of Multi-Modal Physiological Signals\nYear: 2022\n\nAbstract: In recent decades, emotion recognition has received considerable attention. As more enthusiasm has shifted to the physiological pattern, a wide range of elaborate physiological emotion data features come up and are combined with various classifying models to detect one's emotional states. To circumvent the labor of artificially designing features, we propose to acquire affective and robust representations automatically through the Stacked Denoising Autoencoder (SDA) architecture with unsupervised pre-training, followed by supervised fine-tuning. In this paper, we compare the performances of different features and models through three binary classification tasks based on the Valence-Arousal-Dominance (VAD) affection model. Decision fusion and feature fusion of electroencephalogram (EEG) and peripheral signals are performed on hand-engineered features; data-level fusion is performed on deep-learning methods. It turns out that the fusion data perform better than the two modalities. To take advantage of deep-learning algorithms, we augment the original data and feed it directly into our training model. We use two deep architectures and another generative stacked semi-supervised architecture as references for comparison to test the method's practical effects. The results reveal that our scheme slightly outperforms the other three deep feature extractors and surpasses the state-of-the-art of hand-engineered features.","Title: General Mass Property Measurement Equipment for Large-Sized Aircraft\nYear: 2022\n\nAbstract: The accurate measurement of aircraft mass properties, such as the mass, centroid, and moment of inertia (MOI), plays a key role in the precise control of aircraft. In order to obtain high-precision information on the parameters of the mass, centroid, and MOI of an aircraft using a single instrument, an integrated mass property measurement system was developed in this study by analyzing and comparing the latest technologies, especially the function-switching device, which switches the measurement states between the center of mass and the MOI. The purpose of mass property measurement was achieved through single clamping. In addition, the system has strong versatility and expansion and can be used with different tooling or adapter rings to measure the mass properties of aircraft with different shapes. In this paper, the main mechanical structure of the measurement system, the measurement method of relevant mass parameters, and the solution method of the transformation matrix are introduced, and the standard parts and the aircraft were verified experimentally. The test results showed that the mass measurement accuracy was 0.03%, the centroid measurement error was within +/- 0.2 mm, and the measurement accuracy of the MOI was within 0.2%, all of which meet the high-precision measurement requirements for the mass properties.","Title: Deep Learning-Based Cell Detection and Extraction in Thin Blood Smears for Malaria Diagnosis\nYear: 2021\n\nAbstract: Malaria is a major health threat caused by Plasmod-ium parasites that infect the red blood cells. Two predominant types of Plasmodium parasites are Plasmodium vivax (P. vivax) and Plasmodium falciparum (P. falciparum). Diagnosis of malaria typically involves visual microscopy examination of blood smears for malaria parasites. This is a tedious, error-prone visual inspection task requiring microsco...","Title: Automated Drug-Resistant TB Screening: Importance of Demographic Features and Radiological Findings in Chest X-Ray\nYear: 2021\n\nAbstract: Tuberculosis (TB) is a global disease caused by the bacillus Mycobacterium tuberculosis. In recent years, great progress has been made in care and control of drug-sensitive TB, whereas drug-resistant TB continues to be a worldwide public health problem that takes a heavy toll on both patients and the health care system. Early detection of drug resistance during a patient's first visit is very impo...","Title: Self-Distilled Supervised Contrastive Learning for diagnosis of breast cancers with histopathological images\nYear: 2022\n\nAbstract: Convolutional neural networks (CNN) and its variants have been widely used for developing the histopathological image based computer-aided diagnosis (CAD). However, the annotated data are scarce in clinical practice, and limited training samples generally cannot well train the CNN model, resulting in degraded predictive performance. To this end, we propose a novel Self-Distilled Supervised Contrastive Learning (SDSCL) algorithm to improve the diagnostic performance of a CNN-based CAD for breast cancer. In particular, the original histopathological images are first decomposed into H and E stain views, which are served as the augmented sample pairs in the supervised contrastive learning (SCL). Due to the complementary characteristic of the two stain views, this data-driven SCL guide the CNN model to efficiently learn the discriminative features, alleviating the problem of small sample size. Furthermore, self-distillation is embedded into the SCL framework, in which the CNN model jointly distills itself and conducts SCL to further improve feature representation. The proposed SDSCL is evaluated on two public breast histopathological datasets, which outperforms all the compared algorithms. Its average classification accuracy, precision, recall, and F1 scores are 94.28%, 94.64%, 94.58%, 94.34%, respectively, on Bioimaging dataset, and 80.44%, 81.92%, 80.57%, 80.10% on Databiox dataset. The experimental results on two datasets indicate that SDSCL has the potential for the histopathological image based CAD.","Title: An immersed boundary method with implicit body force for compressible viscous flow\nYear: 2022\n\nAbstract: We present a new immersed boundary method for the simulation of compressible viscous flow. The method is based on the singular source approach where the immersed boundary adds surface singularities to the governing equations. The strengths of the surface singularities are treated as algebraic variables under the framework of differential-algebraic equations and are implicitly calculated to enforce the corresponding boundary conditions. Discrete delta functions are used to approximate the surface singularities in the Eulerian grid and interpolate variables back to the surface mesh. A half-explicit Runge-Kutta method is used to achieve desired temporal accuracy. The method has been generalized from the well-known no-slip and isothermal condition to stress and heat flux conditions. The latter necessitates the introduction of further singularities in the stresses and heat flux, which is a new feature of the formulation. Furthermore, the approach has been extended to porous surfaces. The method is also applicable to flow-structure interaction problems. Two- and three-dimensional numerical tests are carried out to demonstrate accuracy. The results are compared with previous numerical and experimental studies or analytical solutions. Finally, a fully three-dimensional fluid-structure interaction simulation of a subsonic parachute is showcased to demonstrate applicability to a real problem.","Title: On the Bilevel Optimization for Remapping Virtual Networks in an HOE-DCN\nYear: 2022\n\nAbstract: Hybrid optical/electrical datacenter network (HOE-DCN) uses the inter-rack networks that consist of both electrical Ethernet switches and optical cross-connects (OXCs), for better cost-efficiency and scalability. Meanwhile, to provision dynamic network services well, the operator of an HOE-DCN needs to deploy virtual networks (VNTs) and remap them adaptively. Therefore, this work studies the problem of VNT remapping in an HOE-DCN from a novel perspective, i.e., the remapping schemes should be optimized for not only the network status after the remapping but also the transition to realize it. Specifically, we model this problem as a bilevel optimization, where the upper-level optimization aims at selecting proper virtual machines (VMs) to migrate such that the estimated latency of VM migration can be minimized, and the lower-level optimization determines the actual scheme of VNT remapping for minimizing the number of resource hot-spots. We first formulate a bilevel mixed integer linear programming (BMILP) model for the bilevel optimization, and then propose a polynomial time algorithm based on enumeration to solve it approximately. Extensive simulations verify the effectiveness of our proposal.","Title: Nucleus image segmentation method based on GAN and FCN model\nYear: 2022\n\nAbstract: The study aims at the problems of rough edges and low accuracy in processing cell nucleus image segmentation in existing image segmentation methods. The use of a generative adversarial network (GAN) and a fully convolutional network (FCN) model to segment cell nuclei is suggested. First, the FCN model is used to perform preliminary segmentation of the cell nucleus image, in which the fully connected layer convolution and skip connection are used to improve the accuracy of image segmentation, then improve the GAN, introduce splitting branches into the discriminator structure, and combine the GAN and the splitting network into one. At the same time, pixel loss is introduced in the generator to obtain a nucleus image that is visually more similar to the real image. Finally, the segmented image output by the FCN model is used as the input of the GAN to achieve high-precision segmentation of the nucleus image. The proposed method is experimentally demonstrated based on the 2018 data science bowl data set. The results show that it can achieve rapid convergence, and the mean intersection over union (MIoU) is 85.34%, which is better than other comparison methods.","Title: HTIDB: Hierarchical Time-Indexed Database for Efficient Storage and Access to Irregular Time-series Health Sensor Data.\nYear: 2022\n\nAbstract: With the enormous amount of data collected by unobtrusive sensors, the potential of utilizing these data and applying various multi-modal advanced analytics on them is numerous and promising. However, taking advantage of the ever-growing data requires high-performance data-handling systems to enable high data scalability and easy data accessibility. This paper demonstrates robust design, developments, and techniques of a hierarchical time-indexed database for decision support systems leveraging irregular and sporadic time series data from sensor systems, e.g., wearables or environmental. We propose a technique that leverages the flexibility of general purpose, high-scalability database systems, while integrating data analytics focused column stores that leverage hierarchical time indexing, compression, and dense raw numeric data storage. We have evaluated the performance characteristics and tradeoffs of each to understand the data access latencies and storage requirements, which are key elements for capacity planning for scalable systems.","Title: Achieving Efficient and Adaptable Dispatching for Vehicle-to-Grid Using Distributed Edge Computing and Attention-Based LSTM\nYear: 2022\n\nAbstract: With the popularity of electric vehicles (EVs), vehicle-to-grid (V2G) technology is attracting increasing attention due to its crucial merit of enabling bidirectional power flows between EVs and grid, so as to enhance the grid security and stability by regulated dispatching. However, the existing V2G approaches are confronted with several unrealizable challenges because of high computational complexity for large-scale EVs and impracticality for future power data acquisition. In this article, an edge computing framework is proposed in a distributed manner to ensure the dispatching efficiently and provide the raw dataset flexibly. Meanwhile, the long short-term memory network is applied to prediction merely by the past and present power data. Moreover, attention mechanism and data clustering are utilized to improve the prediction accuracy and operation robustness. Experiments involving real dataset demonstrated that the proposed V2G scheme is able to achieve very satisfactory dispatching performance with the prediction accuracy up to 98.89%.","Title: Real-Time Prediction System of Train Carriage Load Based on Multi-Stream Fuzzy Learning\nYear: 2022\n\nAbstract: When a train leaves a platform, knowing the carriage load (the number of passengers in each carriage) of this train will support train managers to guide passengers at the next platform to choose carriages to avoid congestion. This capacity has become critical since the onset of the pandemic. However, with the dynamicity of passengers and the speed of trains improved (about 3 minutes travel between stations) as well as the station stop period reduced (60–90 second per station), the real-time prediction is more challenging. This paper presents an intelligent system, which is developed in collaboration with Sydney Trains, for real-time predicting carriage load across a city passenger train network. The system comprises three innovations. First, a fuzzy time-matching method significantly improves prediction accuracy in the uncertain situations and allows noisy historical data to be used for training. Second, the LightGBM model is extended with an incremental learning scheme to make forecasting in real-time possible. Third, a new multi-stream learning strategy that merges data streams with similar concept drift patterns is pioneered to increase the amount of suitable training data while reducing generalization errors. A comprehensive suite of practical tests on real-world datasets demonstrates the merit of these solutions.","Title: Charging RF-Energy Harvesting Devices in IoT Networks With Imperfect CSI\nYear: 2022\n\nAbstract: This article considers energy delivery by a hybrid access point (HAP) to one or more radio-frequency (RF)-energy harvesting devices. Unlike prior works, it considers imperfect and causal channel state information (CSI) and probabilistic constraints that ensure devices receive their required amount of energy over a given planning horizon. To this end, it outlines two novel contributions. The first is a chance-constrained program, which is then solved using a mixed-integer linear program (MILP) coupled with a sample average approximation (SAA) method. The second is a model predictive control (MPC) solution that utilizes the Gaussian mixture model (GMM) and a so-called \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">backoff</i>\n that is used to tighten probabilistic constraints. The results show that the performance of the MPC-based solution is within 8% of the optimal solution with a probability of 90.8%.","Title: Meta-ADD: A meta-learning based pre-trained model for concept drift active detection\nYear: 2022\n\nAbstract: Concept drift is a phenomenon that commonly happened in data streams and need to be detected, because it means the statistical properties of a target variable, which the model is trying to predict, change over time in an unseen way. Most current detection methods are based on a hypothesis test framework. As a result, in these detection methods, a hypothesis test is need to be set, and more importantly, cannot obtain the type of drift. The setting of a hypothesis test requires an understanding of data streams, and cannot obtain the type of concept drift results in the loss of drift information. Hence, in this paper, to get rid of the setting of hypothesis test, and obtain the type of concept drift, we propose Active Drift Detection based on Meta learning (Meta-ADD), a novel framework that learns to classify concept drift by offline pre-training a model on data stream with known drifts, then online fine-tuning model to improve detection accuracy. Specifically, in the pre-trained phase, we extract meta-features based on the error rates of various concept drift, after which a pre-trained model called meta-detector is developed via a prototypical neural network by representing various concept drift classes as corresponding prototypes. In the detection phase, the meta-detector is fine-tuned to adapt to the real data stream via a simple stream-based active learning. Hence, Meta-ADD does not need a hypothesis test to detect concept drifts and identify their types automatically, which can directly support drift understand. The experiment results verify the effectiveness of Meta-ADD.","Title: Evaluating the Applicability of PERSIANN-CDR Products in Drought Monitoring: A Case Study of Long-Term Droughts over Huaihe River Basin, China\nYear: 2022\n\nAbstract: In this study, Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) was evaluated for the assessment of long-term drought monitoring in Huaihe River Basin using daily gauge observation data for the period from 1983 to 2017. The evaluation results show that the PERSIANN-CDR algorithm has a good detection ability for small precipitation events over the whole basin, but a poor ability for extreme precipitation events (>50 mm/day). Daily PERSIANN-CDR estimates perform relatively better in areas with abundant precipitation, while the monthly and yearly PERSIANN-CDR estimates are highly consistent with gauge observations both in magnitude and space. The Standardized Precipitation Index (SPI) at various time scales (3, 6, and 12 months) was calculated based on PERSIANN-CDR and gauge observation, respectively. Grid-based values of statistics derived from those SPI values demonstrate that PERSIANN-CDR has a good ability to capture drought events of each time scale across the basin. However, caution should be applied when using PERSIANN-CDR estimates for basin-scale drought trend analysis. Furthermore, three drought events with long duration and large extent were selected to test the applicability of PERSIANN-CDR in drought monitoring. The results show that it has a good ability to capture when and where droughts occur and how far they spread. Due to the overestimation of small precipitation events, PERSIANN-CDR tends to overestimate the number of extreme droughts and their extents. This needs to be considered in future algorithm improvement.","Title: Detecting group concept drift from multiple data streams\nYear: 2023\n\nAbstract: •Proposing a new type of concept drift group concept drift that commonly exists in multiple data streams.•A group concept drift detection method is proposed through detecting the change of error rate.•A new test statistic, free for any distributions with any dimension p, is proposed.•A novel online hypothesis testing based on our proposed test statistic is developed.","Title: IA-ICGCN: Integrating Prior Knowledge via Intra-event Association and Inter-event Causality for Chinese Causal Event Extraction\nYear: 2022\n\nAbstract: Causal event extraction (CEE) is a joint extraction task of event detection and event causality discrimination, which is of great value on dialogue system, event prediction and so on. However, the ambiguity of Chinese event description and the implicit causal relationship makes the poor performance with existing models. To deal with this problem, we propose a model to incorporate domain knowledge by taking Intra-event Association and Inter-event Causality into account. We use causal indicators to obtain sentences containing causal relationships from domain texts, and use these sentences to construct event association networks and causality transition networks. To obtain complete event expressions and accurate event causality, we use graph convolutional neural networks (GCN) to encode the information of the two networks separately. Finally, all the information are fed into the Bidirectional Long Short-Term Memory networks. Experimental results on two datasets show that our method outperforms the state-of-the-art baselines.","Title: Research on belt foreign body detection method based on deep learning\nYear: 2022\n\nAbstract: Recently, accelerating the improvement in the level of iron ore mining has become extremely important for the sustainable development of the steel industry. Various foreign objects such as steel bars, wood, and plastic pipes easily appear on iron ore belt conveyors, which cause damage to equipment and harm the personal safety of mining workers. Accordingly, a lightweight detection model based on you only look once (YOLO)v3 is proposed in this study. This study first uses the median filter method to preprocess the belt foreign body image to remove the influence of dust and improve the clarity of ore edges. Second, we train the YOLOv3 belt foreign matter detection algorithm based on the selected data set to detect belt foreign matter and evaluate the model based on mean average precision (mAP) and other indicators. Finally, after implementing the sparse training based on the batch normalization (BN) layers, the channel-pruning and layer-pruning strategies are implemented to simplify the YOLOv3 model, followed by parameter fine-tuning. When the accuracy of the model is not affected, our model realizes smaller calculations, faster processing, and a smaller size compared to the original YOLOv3 model. Hence, the model effectively achieves real-time recognition of foreign matter on the ore conveyor belt."],"string":"[\n \"Title: Argos: practical many-antenna base stations\\nYear: 2012\\n\\nAbstract: Multi-user multiple-input multiple-output theory predicts manyfold capacity gains by leveraging many antennas on wireless base stations to serve multiple clients simultaneously through multi-user beamforming (MUBF). However, realizing a base station with a large number antennas is non-trivial, and has yet to be achieved in the real-world. We present the design, realization, and evaluation of Argos, the first reported base station architecture that is capable of serving many terminals simultaneously through MUBF with a large number of antennas (M >> 10). Designed for extreme flexibility and scalability, Argos exploits hierarchical and modular design principles, properly partitions baseband processing, and holistically considers real-time requirements of MUBF. Argos employs a novel, completely distributed, beamforming technique, as well as an internal calibration procedure to enable implicit beamforming with channel estimation cost independent of the number of base station antennas. We report an Argos prototype with 64 antennas and capable of serving 15 clients simultaneously. We experimentally demonstrate that by scaling from 1 to 64 antennas the prototype can achieve up to 6.7 fold capacity gains while using a mere 1/64th of the transmission power.\",\n \"Title: A Time-Delay-Integration Cmos Image Sensor With Pipelined Charge Transfer Architecture\\nYear: 2012\\n\\nAbstract: In this paper, we report a novel Time-Delay-Integration (TDI) CMOS image sensor for low-earth orbit (LEO) nano-satellite imaging application, where limited exposure time and unexpected flight fluctuations are major design challenges. The sensor features programmable integration time per stage, dynamic charge transfer path and tunable well capacity. A prototype chip of 1536x8 pixels was implemented using TSMC 0.18 mu m CMOS image sensor process. Photodiode and other transistors are floor-planned in different arrays, providing small pixel pitch of 3.25 mu m and high fill factor of 57%.\",\n \"Title: XTree: A New XML Keyword Retrieval Model\\nYear: 2009\\n\\nAbstract: As more and more data are represented and stored by XML format, how to query XML data has become an increasingly important research issue. Keyword search is a proven user-friendly way of querying HTML documents, and it is well suited to XML trees as well. However, it is still an open problem in XML keyword retrieval that which XML nodes are meaningful and reasonable to a query, how to find these nodes effectively and efficiently. In recent years, many XML keyword retrieval models have been presented to solve the problem, such as XRANK and SLCA. These models usually return the most specific results and discard most ancestral nodes. There may not be sufficient information for users to understand the returned results easily. In this paper, we present a new XML keyword retrieval model, XTree, which can cover every keyword node and return the comprehensive result trees. For XTree model, we propose Xscan algorithm for processing keyword queries and GenerateTree for constructing results. We analytically and experimentally evaluate the performances of our algorithms, and the experiments show that our algorithms are efficient.\",\n \"Title: Eigenspaces from seriated graphs\\nYear: 2005\\n\\nAbstract: The aim in this paper is to show how the problem of learning the modes of structural variation in sets of graphs can be solved by converting the graphs to strings. We commence by showing how the problem of converting graphs to strings, or seriation, can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision for problems including image segmentation and relaxation labelling. We detail the representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We show how to perform PCA on the strings delivered by our method. By projecting the seriated graphs on to the leading eigenvectors of the sample covariance matrix, we pattern spaces suitable for graph clustering.\",\n \"Title: Fast rendering of foveated volumes in wavelet-based representation\\nYear: 2005\\n\\nAbstract: A foveated volume can be viewed as a blending of multiple regions, each with a different level of resolution. It can be efficiently represented in the wavelet domain by retaining a small number of wavelet coefficients. We exploit the arrangement of those wavelet coefficients to achieve fast volume rendering. The running time is O(n2+m), where n is the width of the rendered image, and m is the number of wavelet coefficients retained for the foveated volume. Our algorithm consists of two phases. The first phase is a fast reconstruction of the super-voxels from the wavelet coefficients, and the second phase renders the super-voxels by carefully tracking rays with different thickness in the super-voxels. No expensive preprocessing on the wavelet coefficients is required. Hence, it is possible to interactively modify different viewing parameters like the transfer functions. A potential application of our algorithm is in remote visualization of large volume data-sets.\",\n \"Title: Graph seriation using semi-definite programming\\nYear: 2005\\n\\nAbstract: Graph seriation is concerned with placing the nodes of a graph in a serial order so that edge consecutive constraints are generally preserved. It is an important task in network analysis problem in routine and bioinformatics. In this paper we show how the problem of graph seriation can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision. The main contribution of the paper is to detail the matrix representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We illustrate the utility of the method for graph-matching and graph-clustering, where it is shown to offer advantages to the graph-spectral approach to seriation.\",\n \"Title: A new indexing strategy for XML keyword search\\nYear: 2010\\n\\nAbstract: With the rapid increase of XML documents on the web, how to index, store and retrieve these documents has become a very popular and valuable problem. At present, there are two normal ways of retrieving XML documents. One is structure-based retrieval; the other is keyword-based retrieval. However, XML keyword search is becoming more and more popular because it is easy to master and manipulate. In XML keyword search system, a key problem is how to store the structure information into XML indices efficiently. At present, Dewey numbers are often used to label XML nodes in XML indices. However, Dewey numbers may lead to redundancy in XML indices. In this paper, we propose a new labeling method called LAF numbers for XML indices and we device a new indexing structure called Two-Layer index for XML keyword retrieval systems. At last, we have conducted an extensive experimental study and the experimental results show that our indexing method achieves better space efficiency than prevailing Dewey-number-based indexing method.\",\n \"Title: Copula Gaussian graphical model for discrete data.\\nYear: 2013\\n\\nAbstract: Copula Gaussian graphical models are capable of describing dependencies between a large number of heterogeneous variables. In this paper, low-complexity algorithms are proposed for learning copula Gaussian graphical models from discrete data. The proposed approach is Monte-Carlo expectation maximization: in the E-step, an efficient Gibbs sampler is applied, and in the M-step, the sparse graphical model is inferred by solving a penalized maximize likelihood problem. The regularization parameter is determined through the BINCO method proposed by Li et al. Numerical results for both synthetic and real data demonstrate the effectiveness of the proposed approach.\",\n \"Title: Clonal selection algorithm with immunologic regulation for function optimization\\nYear: 2005\\n\\nAbstract: Based on the Antibody Clonal Selection Theory of immunology, four immunologic regulation operators inspired by immune regulation mechanism of biology immune system are presented in this paper, and a corresponding algorithm, Immunologic Regulation Clonal Selection Algorithm (IRCSA), is put forward. The essential of immunologic regulation operators is to make fine adjustment among the candidates of the algorithm so as to make interrelations between antibodies more complicated and improve the stability, robustness and accuracy of the algorithm. Numeric experiments of function optimization indicate that the new algorithm is effective and useful.\",\n \"Title: A 10gb/S Wire-Line Transceiver With Half Rate Period Calibration Cdr\\nYear: 2009\\n\\nAbstract: This paper presents the design of a 10Gb/s low power wire-line transceiver in 65nm CMOS process with IV supply voltage. The transmitter occupies an area of 430 mu m x 240 mu m, consumes 50.56mW power and has a 5-order programmable pre-emphasis equalizer. The receiver occupies an area of 300 mu m x 500 mu m. With the novel half rate period calibration clock data recovery (CDR) circuit, the receiver consumes only 52mW power. The receiver combines a low power wideband programmable continuous time linear equalizer (CTLE) and a 3-order decision feedback equalizer (DEE).\",\n \"Title: ArgosV2: a flexible many-antenna research platform\\nYear: 2013\\n\\nAbstract: Many-antenna base stations are a rapidly growing field in wireless research. A plethora of new theoretical techniques have been recently proposed for many-antenna base stations and networks. However, without experimental validation, it is difficult or impossible to predict the practicality and performance of these techniques in real hardware, under complex, rapidly varying, real-world conditions. Indeed, there is a significant demand for a flexible many-antenna research platform which supports rapid prototyping and validation of new massive-MIMO techniques. Leveraging our experience building Argos, a 64-antenna base station prototype, we have designed and built ArgosV2, a compact, powerful, and scalable many-antenna research platform based on WARP. In addition to the physical hardware and mechanical design, we are developing a software framework, ArgosLab, which will provide synchronization and channel estimation, greatly reducing the development effort for a wide range of massive-MIMO techniques. ArgosV2 is intended to provide ultimate scalability and programmability for experimental massive-MIMO research. The modular architecture and real-time capability of ArgosV2 can support up to 100s of base station antennas and 10s of users with streaming applications. For our demonstration, we will unveil a 96-antenna base station which supports real-time streaming applications to 32 users simultaneously.\",\n \"Title: Context-Based Hierarchical Unequal Merging for SAR Image Segmentation.\\nYear: 2013\\n\\nAbstract: This paper presents an image segmentation method named Context-based Hierarchical Unequal Merging for Synthetic aperture radar (SAR) Image Segmentation (CHUMSIS), which uses superpixels as the operation units instead of pixels. Based on the Gestalt laws, three rules that realize a new and natural way to manage different kinds of features extracted from SAR images are proposed to represent superpix...\",\n \"Title: Data broadcasting using mobile FM radio: design, realization and application\\nYear: 2011\\n\\nAbstract: In this work, we offer a novel system, MicroStation (μStation) that allows ubiquitous data broadcasting applications using the FM radio on mobile devices such as smartphones. μStation includes two key modules to enable data broadcasting based on existing mobile FM radio hardware. Channel Selector assigns different FM channels to neighboring μStation broadcasters to avoid collision and guides μStation listeners to find their broadcasting of interest. Data Codec realizes bit-level communication between mobile devices through existing FM radio hardware. We describe an implementation of μStation on the Nokia N900 smartphone, and provide low-level APIs and services to support application development. We also demonstrate two representative applications: Facebook-FM and Sync-Flash. These applications demonstrate the capability of μStation to readily enable a new class of ubiquitous data broadcasting applications on mobile devices.\",\n \"Title: Developing an ontology for the U.S. patent system\\nYear: 2011\\n\\nAbstract: The past few years have experienced an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous information domains making it a challenging task to gather information. In this paper, we develop an ontology to standardize the representation of the patent system in order to overcome the heterogeneity and integrate information from the patent document, court case and file wrapper domains. Through a use case in the bio domain erythropoietin, we demonstrate how this ontology can be used as a tool to improve the learning curve of users gathering information across these multiple information domains. The proposed ontology provides the required semantics to develop automated tools for a variety of purposes including Information Retrieval (IR) and analytics.\",\n \"Title: BeamAdapt: energy efficient beamsteering on mobile devices\\nYear: 2010\\n\\nAbstract: All current mobile devices are omni directional in transmission, which not only limits device energy efficiency but also poses a significant challenge toward network capacity through inter-link interference. In this work, we make mobile devices directional with beamsteering. By allowing a dynamic number of antennas in beamsteering, we reveal an important tradeoff between device energy efficiency and network capacity. We then provide a distributed algorithm called BeamAdapt that allows each mobile device in the network to closely approach the optimal tradeoff, with minimum aggregated device power to achieve certain network capacity. We also offer a cellular system realization of BeamAdapt as well as a Qualnet-based evaluation. The results show the effectiveness of BeamAdapt in device power reduction without sacrificing network throughput.\",\n \"Title: ListOPT: learning to optimize for XML ranking\\nYear: 2011\\n\\nAbstract: Many machine learning classification technologies such as boosting, support vector machine or neural networks have been applied to the ranking problem in information retrieval. However, since the purpose of these learning-torank methods is to directly acquire the sorted results based on the features of documents, they are unable to combine and utilize the existing ranking methods proven to be effective such as BM25 and PageRank. To solve this defect, we conducted a study on learning-to-optimize, which is to construct a learning model or method for optimizing the free parameters in ranking functions. This paper proposes a listwise learning-to-optimize process ListOPT and introduces three alternative differentiable query-level loss functions. The experimental results on the XML dataset of Wikipedia English show that these approaches can be successfully applied to tuning the parameters used in an existing highly cited ranking function BM25. Furthermore, we found that the formulas with optimized parameters indeed improve the effectiveness compared with the original ones.\",\n \"Title: Two-step 3-dimensional sketching tool for new product development\\nYear: 2004\\n\\nAbstract: This paper discusses a two-step virtual reality based conceptual design tool that enables industrial designers to create sketches of their ideas in 3-dimensional space in real time. In the developed sketching tool, the rough shapes of products are generated by tracing the trajectory of the data-gloves worn by the designer. In the model a practical solution is provided to reduce the generation of unnecessary control points. This is achieved by representing each control point by a spherical volume. Once the rough sketching is completed, NURBS surfaces are constructed by the limited number of reference points that are selected from the initial sketch by using a virtual pen. The two-steps sketching technique enables designers to perform their artistic characteristics freely in an intuitive environment and also enables designers to generate parametric representations of the surfaces to be used in CAD/CAM systems for further analysis.\",\n \"Title: Testing BPEL-based Web Service Composition Using High-level Petri Nets\\nYear: 2006\\n\\nAbstract: This paper proposes a technique for analysis and testing BPEL-based web service composition using High-level Petri Nets. To illustrate how these compositions are verified, the relationships between BPEL-based web service composition and High-level Petri Nets is constructed. By analyzing the structure of web service composition based on BPEL, the corresponding HPN is constructed. The dynamism and occurrence are presented in HPN with guard expression with coloured token. After translation, the equivalent HPN of the web service composition based on BPEL can be verified on existing mature tool, and the related researches on HPN, e.g. testing coverage and reduction techniques that have been studied deeply, can be employed in testing of web service composition based on BPEL, optimized test case can be generated based on the HPN translated. An example is provided to illustrate the translation ruled and the automatic verify progress.\",\n \"Title: Graph matching using spectral embedding and alignment\\nYear: 2004\\n\\nAbstract: This paper describes how graph-spectral methods can be used to transform the node correspondence problem into one of point-set alignment. We commence by using the ISOMAP algorithm to embed the nodes of a graph in a low-dimensional Euclidean space. With the nodes in the graph transformed to points in a metric space, we can recast the problem of graph matching into that of aligning the points. Here, we use a variant of the Scott and Longuet-Higgins algorithm to find point correspondences. We experiment with the resulting algorithm on a number of real-world problems.\",\n \"Title: A neural contextual model for detecting perceptually salient contours\\nYear: 2009\\n\\nAbstract: A computational model, inspired by visual cortical mechanisms of contextual modulation, is presented in this paper, and is applied to detect perceptually salient contours. The presented model incorporates two mechanisms of contextual modulation, surround suppression and collinear facilitation. An oriented filterbank generated by Gaussian derivatives and their Hilbert transform is proposed for pre-processing. The operators of surround suppression and collinear facilitation are applied to the orientation energy resulting from the outputs of oriented filterbank. To avoid augmenting the noise when the facilitation operator enhances the saliency parts, we employ a contrast enhancement transformation for the facilitation operator. For drawing the binary contours, we present an automatic thresholding approach for post-processing. The performance of our model is tested by artificial images with heavy noise and nature images with texture background. Results show that the model has a good performance on extracting the salient contours from images.\",\n \"Title: Adaptive Top-k Algorithm in SLCA-Based XML Keyword Search\\nYear: 2010\\n\\nAbstract: Computing top-k results matching XML queries is gaining importance due to the increasing of large XML repositories. In this paper, we propose a novel two-layer-based index construction and associated algorithms for efficiently computing top-k results for SLCA-based XML keyword search. We have conducted expensive experiments and the results show great advantage on efficiency compared with existing approaches.\",\n \"Title: Integrated Optimization of Video Server Resource and Streaming Quality Over Best-Effort Network\\nYear: 2009\\n\\nAbstract: A video streaming server needs to adapt its source/channel encoding parameters (or configurations) to changes in network conditions and to differences in users' connection profiles. The adaptation can be achieved by adjusting parameters such as frame rate, error protection ratio, and resolution. Ideally, the server should adapt the serving configurations with respect to the current network and user conditions to improve received video quality. However, adaptations that optimize playable frame rate require intensive computation, and storing all possible configurations requires a tremendous amount of storage. This brings forth the issues of how to obtain good video quality and reduce server resources usage at the same time. We address this issue in this paper. Our approach is based on the observation that transcoding between certain configurations can be performed very efficiently. We propose a framework to compute a set of configurations to store on the server by considering two opposing goals: (a) maximizing expected received quality of the video, and (b) minimizing server resource usage by lowering transcoding cost and expected number of switches between configurations. The second objective also reduces the number of configurations, and therefore reduces the total storage required. Our framework models the relationship among different configurations in a partial order, formulates the search of a good set of configurations as an energy minimization problem, and we use techniques in image segmentation to solve the problem. Experimental results show that our framework relieves the server load and increases the number of clients served, while only slightly reducing the expected frame rate.\",\n \"Title: Power management of MIMO network interfaces on mobile systems\\nYear: 2012\\n\\nAbstract: High-speed wireless network interfaces are among the most power-hungry components on mobile systems. This is particularly true for multiple-input-multiple-output (MIMO) network interfaces which use multiple RF chains simultaneously. In this paper, we present a novel power management solution for MIMO network interfaces on mobile systems, called antenna management. The key idea is to adaptively disable a subset of antennas and their RF chains to reduce circuit power consumption, when the capacity improvement of using a large number of antennas is small. Antenna management judiciously determines the number of active antennas to minimize energy per bit while satisfying the data rate requirement. This work provides both theoretical framework and system design of antenna management. We first present an algorithm that efficiently solves the problem of minimizing energy per bit and, then offer its 802.11n-compliant system designs. We employ both MATLAB-based simulation and prototype-based experiment to validate the energy efficiency benefit of antenna management. The results showthat antenna management can achieve 21% one-end energy per bit reduction to the front end of the MIMO network interface, compared to a static MIMO configuration that keeps all antennas active.\",\n \"Title: Combining strategies for XML retrieval\\nYear: 2010\\n\\nAbstract: This paper describes Peking University's approaches to the Ad Hoc, Data Centric and Relevance Feedback track. In Ad Hoc track, results for four tasks were submitted, Efficiency, Restricted Focused, Relevance In Context and Restricted Relevance In Context. To evaluate the relevance between documents and a given query, multiple strategies, such as Two-Step retrieval, MAXLCA query results, BM25, distribution measurements and learn-to-optimize method are combined to form a more effective search engine. In Data Centric track, to gain a set of closely related nodes that are collectively relevant to a given keyword query, we promote three factors, correlation, explicitnesses and distinctiveness. In Relevance Feedback track, to obtain useful information from feedbacks, our implementation employs two techniques, a revised Rocchio algorithm and criterion weight adjustment.\",\n \"Title: Vision-based 3D finger interactions for mixed reality games with physics simulation\\nYear: 2008\\n\\nAbstract: Mixed reality applications can provide users with enhanced interaction experiences by integrating virtual and real world objects in a mixed environment. Through the mixed reality interface, a more realistic and immersive control style is achieved compared to the traditional keyboard and mouse input devices. The interface proposed in this paper consists of a stereo camera, which tracks the user's hands and fingers robustly and accurately in the 3D space. To enable a physically realistic experience in the interaction, a physics engine is adopted for the simulating the physics of virtual object manipulation. The objects can be picked up and tossed with physical characteristics, such as gravity and collisions which occur in the real world. Detection and interaction in our system is fully computer-vision based, without any markers or additional sensors. We demonstrate this gesture-based interface using two mixed reality game implementations: finger fishing, in which a player can simulate fishing for virtual objects with his/her fingers as in a real environment, and Jenga, which is a simulation of the well-known tower building game. A user study is conducted and reported to demonstrate the accuracy, effectiveness and comfort of using this interactive interface.\",\n \"Title: Manifold embedding for shape analysis\\nYear: 2010\\n\\nAbstract: Shape analysis played important role in computer vision based tasks. The importance of shape information relies that it usually contains perceptual information, and thus can be used for high level visual information analysis. Currently, there are many ways that shapes can be represented as a structural manner using graphs. Hence shapes can be analyzed by using graph methods. This paper describes how graph-spectral methods can be used to transform the node correspondence problem into one of point-sets alignment. We commence by using the ISOMAP algorithm to embed the nodes of a graph in a low-dimensional Euclidean space. With the nodes in the graph transformed to points in a metric space, we can recast the problem of graph-matching into that of aligning the point-sets. Here we use semidefinite programming to develop a robust point-sets correspondences algorithm. Variations in graph structure using the covariance matrix for corresponding embedded point-positions is captured. We construct a statistical point distribution model for the embedded node positions using the eigenvalues and eigenvectors of the covariance matrix. We show how to use this model to project individual graph, i.e. shape into the eigenspace of the point position covariance matrix. We illustrate the utility of the resulting method for shape analysis and recognition on COIL and MPEG-7 databases.\",\n \"Title: Modeling Spatially-Dependent Extreme Events With Markov Random Field Priors\\nYear: 2012\\n\\nAbstract: A novel spatial model for extreme events is proposed. The model may for instance be used to describe the occurrence of catastrophic events such as earthquakes, floods, or hurricanes in certain regions; it may therefore be relevant for, e.g., weather forecasting, urban planning, and environmental assessment. The model is derived from the following ideas: The above-threshold values at each location are assumed to follow a generalized Pareto (GP) distribution. The GP parameters are coupled across space through Markov random fields, in particular, thin-membrane models. The latter are inferred through an empirical Bayes approach. Numerical results are presented for synthetic and real data (related to hurricanes in the Gulf of Mexico).\",\n \"Title: Perceptual Weighting in LSP-Based Multi-Description Coding for Real-Time Low-Bit-Rate Voice Over IP\\nYear: 2005\\n\\nAbstract: This paper focuses on improving an LSP-based multi-description coding (MDC) scheme for concealing losses when real-time CELP-coded speech data is sent over IP networks. In that scheme, LSP vectors are interleaved because they are highly correlated and can be reconstructed by interpolations when packets are delayed or lost. However, excitation vectors are random in nature and must be replicated in order to conceal losses. To avoid increasing the bit rate of the encoded speech, the excitation vectors are generated from longer subframes. This leads to lower quality of the decoded speech because noise from outside formant regions is over-emphasized, and more excitation information is extracted there. To improve quality, we propose in this paper to modify the perceptual-weighting filter (PWF) in the coder in order to adjust the allocation of noise inside and outside formant regions. We further study a method that selects the PWF in such a way that maintains high quality of the LSP-based MDC across different voice streams and loss scenarios. Experimental results on FS-1016 CELP (4800 bps), ITU G.723.1 ACELP (5300 bps), and ITU G.723.1 MP-MLQ (6300 bps) demonstrate noticeable improvements in decoding quality\",\n \"Title: Machine learning with seriated graphs\\nYear: 2005\\n\\nAbstract: The aim in this paper is to show how the problem of learning the class-structure and modes of structural variation in sets of graphs can be solved by converting the graphs to strings. We commence by showing how the problem of converting graphs to strings, or seriation, can be solved using semi-definite programming (SDP). This is a convex optimisation procedure that has recently found widespread use in computer vision for problems including image segmentation and relaxation labelling. We detail the representation needed to cast the graph-seriation problem in a matrix setting so that it can be solved using SDP. We show how the strings delivered by our method can be used for graph-clustering and the construction of graph eigenspaces.\",\n \"Title: Null controllability for a fourth order parabolic equation.\\nYear: 2009\\n\\nAbstract: In the paper, the null interior controllability for a fourth order parabolic equation is obtained. The method is based on\\n Lebeau-Rabbiano inequality which is a quantitative unique continuation property for the sum of eigenfunctions of the Laplacian.\",\n \"Title: Inferring Brain Networks through Graphical Models with Hidden Variables.\\nYear: 2011\\n\\nAbstract: Inferring the interactions between different brain areas is an important step towards understanding brain activity. Most often, signals can only be measured from some specific brain areas (e.g., cortex in the case of scalp electroencephalograms). However, those signals may be affected by brain areas from which no measurements are available (e.g., deeper areas such as hippocampus). In this paper, the latter are described as hidden variables in a graphical model; such model quantifies the statistical structure in the neural recordings, conditioned on hidden variables, which are inferred in an automated fashion from the data.\",\n \"Title: Copula Gaussian multiscale graphical models with application to geophysical modeling\\nYear: 2012\\n\\nAbstract: Gaussian Multiscale graphical models are powerful tools to describe high-dimensional spatial data; they capture longrange statistical dependencies among distant sites by introducing coarser scales. However, such models are only applicable to Gaussian data. In this paper, a new class of copula Gaussian multiscale graphical models is proposed which possesses rich modeling capabilities and computational efficiency while eliminating the Gaussian assumption. Numerical results are presented for synthetic data as well as data from a few applications in geophysics - models of sea surface temperature and Asian rainfall patterns.\",\n \"Title: Developing a comprehensive patent related information retrieval tool\\nYear: 2011\\n\\nAbstract: In recent years, there has been a massive growth of regulatory and related information available online. This information is distributed across many different domains creating a problem for accessing and managing this data. This paper proposes a framework to access information across two such domains - patents and court cases. The framework is designed to boost the value of a set of patents based on information available in court cases by identifying and cross-referencing mutual information in the two domains. We test our framework by constructing a use case involving the hormone erythropoietin. A corpus of 1150 patents (including 135 closely related patents) and 30 court cases is gathered. Challenges associated with such integration and future plans are briefly discussed.\",\n \"Title: Retrieving information across multiple, related domains based on user query and feedback: application to patent laws and regulations\\nYear: 2010\\n\\nAbstract: In this paper, we present a framework that can process user query for retrieval of information from documents of different properties across multiple domains, with specific application to patent laws and regulations. A case example is given to demonstrate how results from multiple domain searches can be combined using ontology and cross referencing. A user feedback mechanism is also discussed in this paper.\",\n \"Title: Adaptive RF chain management for energy-efficient spatial-multiplexing MIMO transmission\\nYear: 2009\\n\\nAbstract: We present the theoretical foundation, implementation, and experimental evaluation of a novel power-saving mechanism for wireless transmission from multiple-input multiple-output (MIMO) transceivers, called RF chain management. RF chain management seeks to minimize the energy per bit for MIMO transmission, via adaptively choosing the optimal RF chain configuration, and satisfies the minimum data rate requirement at the same time. Our simulation shows that up to 45% and averagely 23% energy per bit reduction can be achieved. We have also built a prototype based on the WARP platform, and our experimental results have proved the feasibility of RF chain management in real systems and under realistic channels.\",\n \"Title: An ontology-based interactive tool to search documents in the U.S. patent system\\nYear: 2011\\n\\nAbstract: The past few years have seen an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous and distributed information sources making it very challenging to retrieve information across multiple domains. In this demonstration, we present a tool that enables users to simultaneously search multiple information domains in the patent system. The presented tool is built upon the Patent System Ontology, which provides both a standardized representation of the patent system domain and required semantics to integrate the various information domains [1], [2]. The tool provides features such as integration with a biomedical knowledge base and recommendations for related articles. Future additions to the tool will provide features to analyze the data both statistically and visually to aid in research. We demonstrate how this tool can be helpful in expediting search and information retrieval in an intelligent and convenient way through a use case in the bio domain -- erythropoietin.\",\n \"Title: String Kernels for Matching Seriated Graphs\\nYear: 2006\\n\\nAbstract: Graph seriation allows the nodes of a graph to be placed in a string order, and then matched using string alignment algorithms. Prior work has used Bayesian methods to derive the string edit costs required in matching. The aim in this paper is to demonstrate how the matching of seriated graphs can be kernelised. To do this we make use of string kernels and show how the parameters of the kernels can be linked to edge density. We illustrate that the graph edit distances computed using the string kernel can be used for graph clustering.\",\n \"Title: Beamsteering on Mobile Devices: Network Capacity and Client Efficiency\\nYear: 2010\\n\\nAbstract: Current and emerging mobile devices are omni directional in wireless\\ncommunication. Such omni directionality not only limits device energy\\nefficiency but also poses a significant challenge toward the capacity of\\nwireless networks through inter-link interference. In this work, we seek to\\nmake mobile clients directional with beamsteering. We first demonstrate that\\nbeamsteering is already feasible to mobile devices such as Netbooks and eBook\\nreaders in terms of form factor, power efficiency, and device mobility. We\\nfurther reveal that beamsteering mobile clients face a unique challenge to\\nbalance client efficiency and network capacity. There is an optimal operating\\npoint for a beamsteering mobile client in terms of the number of antennas and\\ntransmit power that achieve the required capacity with lowest power. Finally,\\nwe provide a distributed algorithm called BeamAdapt that allows each client to\\nclosely approach its optimal point iteratively without central coordination. We\\nalso offer a cellular system realization of BeamAdapt. Using Qualnet-based\\nsimulation, we show that BeamAdapt with four antennas can reduce client power\\nconsumption by 55% while maintaining a required network throughput for a\\nlarge-scale network, compared to the same network with omni directional mobile\\nclients.\",\n \"Title: Beamforming on mobile devices: a first study\\nYear: 2011\\n\\nAbstract: In this work, we report the first study of an important realization of directional communication, beamforming, on mobile devices. We first demonstrate that beamforming is already feasible on mobile devices in terms of form factor, device mobility and power efficiency. Surprisingly, we show that by making an increasingly profitable tradeoff between transmit and circuit power, beamforming with state-of-the-art integrated CMOS implementations can be more power-efficient than its single antenna counterpart. We then investigate the optimal way of using beamforming in terms of device power efficiency, by allowing a dynamic number of active antennas. We propose a simple yet effective solution, BeamAdapt, which allows each mobile client in a network to individually identify the optimal number of active antennas with guaranteed convergence and close-to-optimal performance. We finally report a WARP-based prototype of BeamAdapt and experimentally demonstrate its effectiveness in realistic environments, and then complement the prototype-based experiments with Qualnet-based simulation of a large-scale network. Our results show that BeamAdapt with four antennas can reduce the power consumption of mobile clients by more than half compared to a single antenna, while maintaining a required network throughput.\",\n \"Title: Fully utilize feedbacks: language model based relevance feedback in information retrieval\\nYear: 2011\\n\\nAbstract: Relevance feedback algorithm is proposed to be an effective way to improve the precision of information retrieval. However, most researches about relevance feedback are based on vector space model, which can't be used in other more complicated and powerful models, such as language model and logic model. Meanwhile, other researches are conceptually restricted to the view of a query as a set of terms, and so cannot be naturally applied to more general case when the query is considered as a sequence of terms and the frequency information of a query tern is considered. In this paper, we mainly focuses on relevant feedback Algorithm based on language model. We use a mixture model to describe the process of generating document and use EM to solve model's parameters. Our research also employs semi-supervised learning to calculate collection model and proposes an effective way to obtain feedback from irrelevant documents to improve our algorithm.\",\n \"Title: System optimization of a 5.8 GHz ETC receiver using Memetic algorithm\\nYear: 2011\\n\\nAbstract: ETC (Electronic Tolling Collection) systems develop rapidly in China in order to relieve the traffic congestion. As the key component of the ETC system, the design of the Radio Frequency (RF) transceiver is usually a tedious and experienced based work due to its high non-linearity. An automatic system level optimization method based on Memetic algorithm (MA) is proposed in this paper. A fitness function describing the relationship between receiver output signal-to-noise ratio (SNRout) and 9 system level parameters was derived and was optimized by the MA method. The correctness of the MA method was verified by the ADS simulation. A close result was obtained and the effects of the 9 parameters on the SNRout were discussed. The future design of the whole transceiver system can be based on this method.\",\n \"Title: Membrane Sculpting By F-Bar Domains Studied By Molecular Dynamics Simulations\\nYear: 2013\\n\\nAbstract: Interplay between cellular membranes and their peripheral proteins drives many processes in eukaryotic cells. Proteins of the Bin/Amphiphysin/Rvs (BAR) domain family, in particular, play a role in cellular morphogenesis, for example curving planar membranes into tubular membranes. However, it is still unclear how F-BAR domain proteins act on membranes. Electron microscopy revealed that, in vitro, F-BAR proteins form regular lattices on cylindrically deformed membrane surfaces. Using all-atom and coarse-grained (CG) molecular dynamics simulations, we show that such lattices, indeed, induce tubes of observed radii. A 250 ns all-atom simulation reveals that F-BAR domain curves membranes via the so-called scaffolding mechanism. Plasticity of the F-BAR domain permits conformational change in response to membrane interaction, via partial unwinding of the domains 3-helix bundle structure. A CG simulation covering more than 350 mu s provides a dynamic picture of membrane tubulation by lattices of F-BAR domains. A series of CG simulations identified the optimal lattice type for membrane sculpting, which matches closely the lattices seen through cryo-electron microscopy.\",\n \"Title: Extreme-value graphical models with multiple covariates\\nYear: 2014\\n\\nAbstract: To assess the risk of extreme events such as hurricanes and floods, it is crucial to develop accurate extreme-value statistical models. Extreme events often display heterogeneity, varying continuously with a number of covariates. Previous studies have suggested that models considering covariate effects lead to reliable estimates of extreme value distributions. In this paper, we develop a novel model to incorporate the effects of multiple covariates. Specifically, we analyze as an example the extreme sea states in the Gulf of Mexico, where the distribution of extreme wave heights changes systematically with location and wind direction. The block maxima at each location and sector of wind direction are assumed to follow the Generalized Extreme Value (GEV) distribution. The GEV parameters are coupled across the spatio-directional domain through a graphical model, particularly, a multidimensional thin-membrane model. Efficient learning and inference algorithms are then developed based on the special characteristics of the thin-membrane model. Numerical results for both synthetic and real data indicate that the proposed model can accurately describe marginal behavior of extreme events.\",\n \"Title: Modeling spatial extremes via ensemble-of-trees of pairwise copulas\\nYear: 2014\\n\\nAbstract: Assessing the risk of extreme events in a spatial domain, such as hurricanes, floods and droughts, presents unique significance in practice. Unfortunately, the existing extreme-value statistical models are typically not feasible for practical large-scale problems. Graphical models are capable of handling enormous number of variables, yet have not been explored in the realm of extreme-value analysis. To bridge the gap, an extreme-value graphical model is introduced in this paper, i.e., ensemble-of-trees of pairwise copulas (ETPC). In the proposed graphical model, extreme-value marginal distributions are stitched together by means of pairwise copulas, which in turn are the building blocks of the ensemble of trees. By exploiting this particular structure, novel efficient inference algorithms are derived that are applicable to large-scale statistical problems involving extreme values. It is proven that, under mild conditions, the ETPC model exhibits the favorable property of tail-dependence between an arbitrary pair of sites (variables), and therefore is reliable to capture the dependence between extremes at different sites. Real data results further demonstrate the advantages of the ETPC model.\",\n \"Title: Network inference and change point detection for piecewise-stationary time series\\nYear: 2014\\n\\nAbstract: Graphical models are powerful tools to describe complex systems. Especially sparse graphical models are currently en vogue, as they allow us to infer network structure from multiple time series (e.g., functional brain networks from multichannel electroencephalograms). So far, most of the literature deals with stationary time series, whereas real-life time series often exhibit non-stationarity. In this paper, techniques are proposed to infer graphical models from piecewise stationary time series; first change point are detected in the time series, and then graphical models are inferred for each stationary segment. Specifically, a low-complexity algorithm based on Pruned Exact Linear Time method is proposed to identify change points. Copula Gaussian graphical models (with and without hidden variables) are then generated for each stationary segment. The crux of the proposed approach is that it determines the number and location of the change points as well as the graphical models in a fully automated manner. Results for both synthetic data and scalp electroencephalograms of epileptic seizure patients are provided to validate the model.\",\n \"Title: Sensor fault detection by sparsity optimization\\nYear: 2014\\n\\nAbstract: Measurement faults in control systems may result in permanent damages to the system components. Therefore, sensor validation is essential before the measurements are used for any system reconfiguration. In this paper, a statistical approach for sensor fault identification is proposed. Specifically, the potential sensor fault is assumed to be an additive bias term in the measurement model. The problem of fault identification is formulated as a least-squares optimization problem with an ℓ1 penalty on the bias term. An algorithm is further introduced to determine the regularization parameter automatically. Experimental results show that the proposed method can accurately detect multiple sensor failures from noisy measurements.\",\n \"Title: Combating inter-cell interference in 802.11ac-based multi-user MIMO networks\\nYear: 2014\\n\\nAbstract: In an 802.11ac-based MU-MIMO network comprised of multiple cells1, inter-cell interference allows only a single AP to serve its clients at the same time, significantly limiting the network capacity. In this work, we overcome this limitation by letting the APs and clients in interfering cells coordinately cancel the inter-cell interference using their antennas for beamforming. To achieve such coordinated interference cancellation in a practical way, we propose a novel two-step optimization. First, without requiring any channel knowledge, each AP and client optimizes the use of its antennas for either data communication or inter-cell interference cancellation, in order to maximize the total number of deliverable streams in the MU-MIMO network. Second, with only partial channel knowledge, each AP and client optimizes their beamforming weights after the optimal antenna usage has been identified in the first step. Our solution, CoaCa, integrates this two-step optimization into 802.11ac with small modifications and negligible overhead, allowing each AP and client to locally perform the two-step optimization. Our experimental evaluation indicates that for a MU-MIMO network with two cells, by cancelling the inter-cell interference CoaCa can convert the majority of the expected number of streams increase (50%-67%) into network capacity improvement (41%-52%).\",\n \"Title: A dual-exposure in-pixel charge subtraction CTIA CMOS image sensor for centroid measurement in star trackers\\nYear: 2014\\n\\nAbstract: In this work, we present a CMOS image sensor for star centroid measurement in star trackers. The analysis of the star tracker system shows that long integration will cause \\\"tail effect\\\" in the star image. It significantly reduces the signal magnitude, which in turn increases the centroiding errors. In order to capture limited photons generated from dim stars within shortened integration time, we propose a new capacitive transimpedance amplifier (CTIA) pixel architecture with a small integration capacitor. On the other hand, bright stars can easily saturate the pixels, which can also induce significant measurement errors. To avoid pixel saturation, the pixel is able to perform in-pixel charge subtraction based on photocurrent thresholding. In order to validate the pixel design, we have fabricated a test chip consisting of a 4×4 pixel array using Global Foundry 65 nm mixed signal CMOS process.\",\n \"Title: Spatio-temporal graphical models for extreme events\\nYear: 2014\\n\\nAbstract: We propose a novel statistical model to describe spatio-temporal extreme events. The model can be used to estimate extreme-value temporal pattern such as seasonality and trend, and further to predict the distribution of extreme events in the future. The basic idea is to explore graphical models to capture the highly structured dependencies among extreme events measured in time and space. More explicitly, we first assume the single observation at each location and time point follows a Generalized Extreme Value (GEV) distribution. The spatio-temporal dependencies are further encoded via graphical models imposed on the GEV parameters. We develop efficient learning and inference algorithms for the resulting non-Gaussian graphical model. Results of both synthetic and real data demonstrate the effectiveness of the proposed approach.\",\n \"Title: Design and characterization of radiation-tolerant CMOS 4T Active Pixel Sensors\\nYear: 2014\\n\\nAbstract: The design and radiation characterization of pinned photodiode 4T Active Pixel Sensors (APS) is presented in this paper. Four types of pixel layout are characterized and irradiated by 60Co γ-rays up to 170krad(Si). A variety of radiation hardening techniques are applied in these pixels. The variations between the four pixels allow us to optimize the design parameters for radiation hardness. Our experimental results exhibit increase in dark current and its non-uniformity after radiation. It is also found that Enclosed Layout Transistor (ELT) transfer gate (TX) becomes the major cause of the dark current increase. The dark current increase attributed to the shallow trench isolation (STI) around the photodiode can be mitigated by recessed-STI photodiode structure when the total dose is low. Large floating diffusion (FD) shows more immunity to the radiation-induced leakage current and random noise.\",\n \"Title: Rotation of foveated image in the wavelet domain\\nYear: 2004\\n\\nAbstract: An advantage of wavelet transform is its efficiency in rep- resenting natural images, that is, a natural image can be accurately represented by only a small number of retained wavelet coefficients. It is interesting to know whether some common image operations, e.g. rotation, can be performed very fast in wavelet domain. Preferably, the running time should depend only on the number of retained coefficients, not the size of the original image. However, it is not clear how this can be achieved. In this paper, we consider rota- tion, and images with a special structure: foveated images. Wavelet coefficients of a foveated image vanish outside an arrangement of circles. We exploit this structure to derive algorithms that accurately approximate rotation. The run- ning time is �(m) where m is the number of retained coef- ficients. Experiments show the accuracy of the approxima- tion.\",\n \"Title: An amelioration Particle Swarm Optimization algorithm\\nYear: 2010\\n\\nAbstract: A new amelioration Particle Swarm Optimization (SARPSO) based on simulated annealing (SA), asynchronously changed learning genes (ACLG) and roulette strategy was proposed because the classical Particle Swarm Optimization (PSO) algorithm was easily plunged into local minimums. SA had the ability of probability mutation in the search process, by which the search processes of PSO plunging into local minimums could be effectively avoided; ACLG could improve the ability of global search at the beginning, and it was propitious to be convergent to global optimization in the end; the roulette strategy could avoid prematurity of the algorithm. The emulation experiment results of three multi-peaking testing functions had shown the validity and practicability of the SARPSO algorithm.\",\n \"Title: CRIM-FCHO: SAR Image Two-Stage Segmentation With Multifeature Ensemble\\nYear: 2016\\n\\nAbstract: This paper investigates the synthetic aperture radar (SAR) image segmentation in terms of feature analysis and fusion and develops a new algorithm based on multifeature ensemble accordingly. This paper is characterized by two aspects. First, multiple heterogeneous features are extracted to accurately describe the objects in SAR images. These features are then integrated in the feature level and the similarity level, respectively, to avoid the mutual influences between different kinds of features and maximize the discriminability of the similarity measure between objects. Second, a two-stage algorithm consisting of a coarse merging stage and a fine classification stage is proposed. In the coarse merging stage, a context-based region iterative merging algorithm is designed to merge most of the unambiguous superpixels in image domain at a high speed. In the fine classification stage, a fuzzy clustering algorithm incorporating hybrid optimization is developed to balance the efficiency and the robustness of the algorithm by simultaneously searching heuristically in the complete high-dimension feature space and searching along the direction of the gradient steepest descent in each feature subspace. The effectiveness of the proposed method has been successfully validated on synthetic and real SAR images.\",\n \"Title: Robustly building keypoint mappings with global information on multispectral images\\nYear: 2015\\n\\nAbstract: This paper proposes an approach to robustly build keypoint mappings on multispectral images. The distinctiveness and repeatability of descriptors often decrease significantly on multispectral images and thus give unreliable keypoint mappings. To complement this decrease, global information over entire images is induced in this work to evaluate keypoint mappings. Initial keypoint mappings are established by utilizing descriptors. A pair of keypoint mappings determines a similarity transformation T, and then it is evaluated with the induced global information that is defined to be the similarity metric between the reference image and the transformed image by T. A process is utilized that iteratively considers the pairs of keypoint mappings and searches the best reference matched keypoint for every test keypoint. Experimental results show that the proposed approach can provide more reliable keypoint mappings than SIFT, ORB, FREAK, and ISS on multispectral images.\",\n \"Title: Miniaturized optical neuroimaging in unrestrained animals.\\nYear: 2015\\n\\nAbstract: The confluence of technological advances in optics, miniaturized electronic components and the availability of ever increasing and affordable computational power have ushered in a new era in functional neuroimaging, namely, an era in which neuroimaging of cortical function in unrestrained and unanesthetized rodents has become a reality. Traditional optical neuroimaging required animals to be anesthetized and restrained. This greatly limited the kinds of experiments that could be performed in vivo. Now one can assess blood flow and oxygenation changes resulting from functional activity and image functional response in disease models such as stroke and seizure, and even conduct long-term imaging of tumor physiology, all without the confounding effects of anesthetics or animal restraints. These advances are shedding new light on mammalian brain organization and function, and helping to elucidate loss of this organization or ‘dysfunction’ in a wide array of central nervous system disease models.\",\n \"Title: Modeling Spatio-Temporal Extreme Events Using Graphical Models.\\nYear: 2016\\n\\nAbstract: We propose a novel statistical model to describe spatio-temporal extreme events. The model can be used, for instance, to estimate extreme-value temporal pattern such as seasonality and trend, and further to predict the distribution of extreme events in the future. Such model usually involves thousands or even millions of variables in the spatio-temporal domain, whereas only one single observation ...\",\n \"Title: Research on Automate Discovery of Deep Web Interfaces.\\nYear: 2015\\n\\nAbstract: The main means to obtain information from Deep Web is submitting query condition through the provided query interfaces, so it is the first problem that needs to be solved for Deep Web data integration system. At present, most researchers think of query interface is merely defined within the form html tag. This paper firstly proposes the concept of interface block, then designs the interface block location method based on page and vision information, and finally takes the judgment of whether interface block is a query interface or not as the special multi-class classification problems and by applying classification algorithm combining C4.5 decision tree and SVM. The experiment adopts TEL-8 data sets of UIUC, and the findings indicate that the method in this paper get an accuracy of 97.30%, and has good feasibility and practicability.\",\n \"Title: Variational Bayes Learning Of Multiscale Graphical Models\\nYear: 2015\\n\\nAbstract: Multiscale (multisolution) graphical models have gained widespread popularity in recent years, since they enjoy rich modeling power as well as efficient inference procedures, Existing approaches to learning multiscale graphical models often leverage the framework of penalized likelihood, and therefore suffer from the issue of regularization selection. In this paper, we propose a novel method to learn multiscale graphical models from the Bayesian perspective. More specifically, the regularization parameters are treated as random variables that follow Gamma distributions, We then derive an efficient variational Bayes algorithm to learn the model, and further demonstrate the advantages of the proposed method through numerical experiments.\",\n \"Title: An 8-stage time delay integration CMOS image sensor with on-chip polarization pixels\\nYear: 2015\\n\\nAbstract: Machine vision applications involving the assistance of robots for scene mapping or object classification encounter issues when faced with smooth transparent surfaces, such as glass. Specular reflection from such surfaces saturate the image sensor pixels, restricting their vision of objects beyond the surface. The problem is aggravated by the movement of the robot, making traditional approaches unfeasible. We propose a solution that uses on-chip polarizers to limit the specular reflection and improve scene visibility while overcoming the limited SNR and motion artifacts by using a time delay integration image sensor. We have fabricated a 256×8×5 prototype sensor using a 0.18μm CIS process which achieves a DR of 52.3dB while providing an SNR improvement of 8.8dB over a single-stage linear scanner.\",\n \"Title: An ontology to integrate multiple information domains in the patent system\\nYear: 2011\\n\\nAbstract: In recent years, there has been an explosive growth in scientific and regulatory documents related to the patent system. Relevant information is siloed into many heterogeneous information domains making it very challenging to retrieve information across multiple domains. In this paper, we develop an ontology for the patent system to integrate information from the patent and court case domains. Through a use case erythropoietin, we demonstrate how this ontology can be used to enhance information retrieval across multiple domains.\",\n \"Title: Forwarding Schemes for EM-based Wireless Nanosensor Networks in the Terahertz Band\\nYear: 2015\\n\\nAbstract: Electromagnetic-based Wireless NanoSensor Networks (EM-WNSNs) operating in the TeraHertz (THz) band (0.1 THz--10 THz) has been in focus recently because of potential applications in nano-scale scenarios. However, one major hurdle for advancing nano-scale communications is the lack of suitable networking protocols to address current and future needs of nanonetworks. Working together with routing that finds the path from a source to destination, forwarding is a networking task of sending a packet to the next-hop along its path to the destination. While forwarding has been straightforward in traditional wired networks, forwarding schemes now play a vital role in determining wireless network performance. In this paper, we propose a channel-aware forwarding scheme and compare it against traditional forwarding schemes for wireless sensor networks. To fit the peculiarity of EM-WNSNs, the channel-aware forwarding scheme makes forwarding decision considering the frequency selective pecularities of the THz channel which are undesirable from a networking perspective. It is shown through simulation that the proposed channel-aware forwarding scheme outperforms traditional forwarding schemes in terms of the end-to-end capacity while maintaining comparable performance for delay.\",\n \"Title: Variational Bayes learning of graphical models with hidden variables\\nYear: 2015\\n\\nAbstract: Hidden variable graphical models are powerful tools to describe high-dimensional data; they capture dependencies between observed variables by introducing a suitable number of hidden variables. Present methods for learning the dependence structure of hidden variable graphical models are derived from the idea of maximizing penalized likelihood, and hence are associated with the troublesome problem of regularization selection. In this paper, we show that this problem can be successfully circumvented by treating the penalty parameters as random variables and describing the hidden variable graphical models in a Bayesian formulation. An efficient variational Bayes algorithm is further developed to adaptively learn the graphical model as well as the distribution of penalty parameters. Numerical results from both synthetic and real data show that the proposed variational Bayes method yields comparable or better performance than the stability selection based maximum penalized likelihood method, yet it requires several orders of magnitude less computational time.\",\n \"Title: A time delay integration CMOS image sensor with online deblurring algorithm\\nYear: 2015\\n\\nAbstract: This paper presents an online deblurring (ODB) algorithm for time delay integration (TDI) CMOS image sensor (CIS) used in small remote imaging systems, where image quality is degraded due to vibration caused by different factors. The ODB algorithm can detect and compensate the image shift so as to produce sharp TDI images. A 256×8-pixel prototype chip was fabricated using a 0.18μm CIS technology, which contains 8 TDI stages, column-parallel TDI accumulation and online deblurring circuits. The 4-transistor active pixel sensor (4T-APS) is applied, with the pixel size of 6.5μm×6.5μm and the fill factor of 28%.\",\n \"Title: A Global-Shutter Centroiding Measurement CMOS Image Sensor With Star Region SNR Improvement for Star Trackers.\\nYear: 2016\\n\\nAbstract: A star tracker is a critical sensor for determining and controlling the attitude of a satellite. It utilizes a complementary metal-oxide-semiconductor (CMOS)-active pixel sensor to map the star field onto the focal plane. Starlight is measured and star centroids are calculated to estimate attitude knowledge. In this paper, we present a CMOS image sensor for star centroid measurement in star tracke...\",\n \"Title: An Antivibration Time-Delay Integration CMOS Image Sensor With Online Deblurring Algorithm.\\nYear: 2016\\n\\nAbstract: This paper presents an antivibration time-delay integration (TDI) CMOS image sensor (CIS) for small remote imaging systems, introducing a hardware-implemented online deblurring (ODB) algorithm to address the image blur problems caused by vibrations. The proposed sensor has eight TDI stages, column-parallel TDI accumulating and ODB circuits. A 256×8-pixel prototype chip was fabricated using a 0.18-...\",\n \"Title: Variational bayes learning of time-varying graphical models\\nYear: 2016\\n\\nAbstract: We propose a tuning-free Bayesian approach to learn a set of sparse graphical models, in which adjacent graphs share similar structures. This model can be applied to estimating dynamic networks that evolve smoothly with regard to a covariate (e.g., time). Specifically, a novel structured spike and slab prior is constructed. This prior allows time-varying sparsity pattern by smoothing the spike probabilities across time using a Gauss-Markov chain. An efficient variational Bayes (VB) algorithm is then derived to learn the model, and is compared to related frequentist methods in the literature. We further extend the proposed mechanism to learn graphical models for multivariate time series in frequency domain. As an example, we analyze scalp electroencephalograms (EEG) recordings of patients at early stages of Alzheimer disease (AD), and quantify the loss of synchrony in comparison with control subjects.\",\n \"Title: Anti-Starvation Channel Assignment With Global Conflict Set Selection in IEEE 802.11 WMNs.\\nYear: 2016\\n\\nAbstract: Channel assignment algorithms play a critical role in the performance of IEEE 802.11 wireless mesh network by allocating channels and regulating interference between channels. In a channel assignment algorithm, the strategy used to compute a conflict set is crucial because it directly determines the allocation of channels to a given link. This paper investigates the fairness and prevention of flow starvation due to different strategies in selecting conflict sets in a channel assignment algorithm. We apply five different conflict set selection strategies to a vanilla channel assignment algorithm and compare the resulting network performance of each strategy. Our findings show that none of these conflict set selection strategies prevent flow starvation and achieve poor fairness as they only consider \\\\\\\"local channel conflict\\\\\\\" and lack the consideration of \\\\\\\"global channel conflict\\\\\\\". We propose a new conflict set selection for channel assignment algorithms called anti-starvation channel assignment (ASCA). Our proposed algorithm considers both local and global conflict to alleviate flow starvation and improves fairness by 62% (with respect to the fairness index) compared with the best result from existing conflict set selection strategies. To the best of our knowledge, the proposed ASCA is the first one to analyse channel assignment algorithms using the concept of local and global conflict sets.\",\n \"Title: A Two-Step Prediction ADC Architecture for Integrated Low Power Image Sensors.\\nYear: 2017\\n\\nAbstract: This paper presents a two-step prediction method for the design of low-power column-parallel analog-to-digital converters (ADC) in CMOS image sensors. The proposed prediction method takes advantage of the spatial likelihood of natural scenes, which shows strong correlations between neighboring pixels in the image. Based on this property, the proposed method predicts the MSBs of the selected pixel ...\",\n \"Title: Control plane innovations to realize dynamic formulation of multicast sessions in inter-DC software-defined elastic optical networks.\\nYear: 2017\\n\\nAbstract: It is known that to support the applications such as datacenter backup and migration, multicast should be supported efficiently in inter-datacenter (inter-DC) networks to carry the corresponding point-to multiple -point communications. Moreover, due to the traffic dynamics in inter-DC networks, we might have to consider the case that the multicast members can join or leave a multicast session dynamically. Therefore, in this work, we try to leverage control plane innovations to realize dynamic formulation of multicast sessions in inter-DC software-defined elastic optical networks (SD-EONS), which are equipped with multicast-incapable bandwidth-variable wavelength selective switches (MI-BV-WSS'). Here, one key issue to address is that the continuous changing of multicast group members can degrade the optimality of a multicast-tree. Hence, we propose to rearrange the multicast-trees adaptively to reduce their spectrum usage. Meanwhile, we try to minimize the frequency of rearrangements to avoid unnecessary operation complexity. Based on these considerations, we propose several multicast-tree rearrangement algorithms for updating multicast sessions dynamically with lightpath reroutings in inter DC SD-EONs. Both partial and full multicast-tree rearrangements are studied. Simulation results indicate that the proposed algorithms can rearrange the multicast-trees intelligently such that the blocking probability can be reduced effectively with the least lightpath reroutings. Next, based on these theoretical investigations, we consider how to implement the proposed algorithms in the control plane of an inter-DC SD-EON, We extend the OpenFlow (OF) protocol to support the dynamic formulation of multicast sessions and also design the functional models in the control plane elements to realize multicasttree rearrangements. Experiment results verify the effectiveness of our proposed algorithms and system design. (C) 2016 Elsevier B.V. All rights reserved.\",\n \"Title: Outlier-insensitive Kalman smoothing and marginal message passing.\\nYear: 2016\\n\\nAbstract: We propose a new approach to outlier-insensitive Kalman smoothing based on normal priors with unknown variance (NUV). In contrast to prior work, the actual computations amount essentially to iterations of a standard Kalman smoother (with few extra computations). The proposed approach is easily extended to nonlinear estimation problems by combining the outlier detection with an extended Kalman smoother. For the Kalman smoothing, we consider both a Modified Bryson-Frasier smoother and the recently proposed Backward Information Filter Forward Marginal smoother, neither of which requires matrix inversions.\",\n \"Title: On-demand efficient polling for nanonetworks under dynamic IoT backhaul network conditions\\nYear: 2016\\n\\nAbstract: Driven by the high sensing resolution provided by advanced nano technologies, Electromagnetic-based Wireless Nano Sensor Networks (EM-WNSNs) operating in the terahertz (THz) band is becoming an integral part of the Internet of Things (IoT). Data acquisition for EM-WNSNs face two challenges: the dynamic IoT backhaul bandwidth and THz channel conditions that jointly impact resource utilization efficiency. Specifically, the mismatch between the demands of the EM-WNSNs and the available bandwidth of the backhaul link reduces the bandwidth efficiency of IoT backhaul or the energy efficiency of EM-WNSNs. To address the new constraints that emerge from the EM-WNSN, an On-demand Efficient (OE) polling is proposed for the backhaul tier of EM-WNSNs which is composed of nano sinks that aggregate and transport data from nano sensors to the IoT gateway. The OE polling adjusts the packet aggregation process of nano sinks according to the up-to-date network conditions and we show that it achieves both high bandwidth efficiency for IoT backhaul and high energy efficiency for EM-WNSNs. To the best of our knowledge, OE polling is the first data acquisition scheme that connects EM-WNSNs with IoT by taking into consideration the dynamic IoT backhaul bandwidth and THz channel conditions.\",\n \"Title: Opportunistic Geographic Forwarding in Wireless Sensor Networks for Critical Rare Events\\nYear: 2016\\n\\nAbstract: Wireless sensor networks for rarely occurring critical events must maintain sensing coverage and low latency network connectivity to ensure event detection and subsequent rapid propagation of notification messages. Existing geographic forwarding algorithms have proved successful in providing energy efficient network connectivity for arbitrary topologies where sensing coverage is not guaranteed. This paper proposes a location aware algorithm for Swift Opportunistic Forwarding of Infrequent Events (SOFIE) that takes advantage of geometric properties common to sensing networks providing perfect area coverage. The algorithm is shown to deliver more rapid message propagation than two established, general purpose geographic forwarding algorithm in optimally and randomly placed networks of varied sensing node density. Further, the algorithm is shown to maintain this advantage when deployed in a coverage preserving, duty-cycled sensing network where nodes may power down whilst the network is actively forwarding event notification messages.\",\n \"Title: TTL-based efficient forwarding for the backhaul tier in nanonetworks\\nYear: 2017\\n\\nAbstract: Electromagnetic-based Wireless Nano Sensor Networks (EM-WNSNs) working in the TeraHertz (THz) band are developing fast because of the high sensing resolution that benefits a wide range of applications. In EM-WNSNs, nano sinks that aggregate data from nano sensors to the Internet of Things (IoT) gateway collectively form a backhaul tier of EM-WNSNs. Unlike the data tier composed of densely deployed nano sensors that are closely connected, the backhaul tier consisting of less dense nano sinks is highly vulnerable to the dynamic channel states of THz band that is sensitive to the surrounding humidity change. Thus, a forwarding scheme that adapts to dynamic channel states is needed to ensure both connectivity and efficiency of data transfers over the backhaul. Current channel-aware approaches are based on complex hardware support that cannot be deployed on nano devices due to the size constraints. To solve this problem, the Time-To-Live (TTL)-based Efficient Forwarding (TEFoward) with low complexity is proposed for the backhaul tier of multi-hop polling-based EM-WNSNs. In TEFoward, the functions carried by polling beacons are diversified besides data extraction. Nano sinks select forwarders and direct packets based on the duplicate counts and TTL values of polling beacons which reflect the latest topology information. Demanding lightweight resource support, TEFoward achieves high end-to-end data delivery ratio and energy efficiency.\",\n \"Title: Fitness evaluation for channel assignment algorithms in IEEE 802.11 WMNs\\nYear: 2017\\n\\nAbstract: Wireless mesh networks (WMNs) cannot utilize the full capability of these radio technologies without an effective channel assignment algorithm. Existing metrics for characterising the efficacy of channel assignment algorithms poorly reflect the goodput distribution in WMNs. In this paper, we develop a fitness evaluation algorithm that feeds back several indicators of efficacy to a channel assignment algorithm and evaluate the resulting goodput distribution. To the best of our knowledge, our algorithm is the first to evaluate the fitness of channel assignment algorithms with goodput distribution, average goodput, and fairness index. Simulation results show that our evaluation algorithm provides accurate prediction of goodput distribution, average goodput, and fairness index with errors below 8%.\",\n \"Title: Energy Efficient Routing Algorithm Using Software Defining Network for WSNs via Unequal Clustering.\\nYear: 2016\\n\\nAbstract: Clustering and multi-hop routing algorithms substantially prolong the lifetime of wireless sensor networks (WSNs). However, in multi-hop routing, the nodes near the sink are burdened with heavy relay traffic and tend to exhaust their energy very quickly. Thus, the energy hole arises. In this paper, we propose an SDN-based Unequal Clustering Routing (SDUCR) protocol for WSNs, which consists of a Centralized Unequal Clustering algorithm (CUCA) and a Connected Graph Based Minimum Energy Consumption (CGMEC) multi-hop routing algorithm. We use the centralized intelligence of Software Defined Network (SDN) to implement clustering and routing. Our CUCA is used to partition the network into clusters of unequal size based on residual energy and degree of sensor nodes. The CGMEC algorithm constructs a routing tree among cluster heads which ensures the connectivity among nodes and balances the communication cost of all nodes. Simulation results show that our SDUCR protocol balances the energy consumption among sensor nodes and achieves an obvious improvement on the network lifetime.\",\n \"Title: Production Strategy With Substitution Under Cap-And-Trade Regulation\\nYear: 2016\\n\\nAbstract: This paper researches the two products production strategy under cap and trade policies by newsboy model. The green product could be regarded as an equivalent of the regular product. The useful conclusions can be obtained: 1) The establishment of cap and trade will benefit for the improvement of manufacture performance. 2) After green technology input, the quantity of regular product will raise and the quantity of green product under cap and trade will decrease. 3) There is expectant profit that could be earned through selling extra carbon emission or buy less carbon emission from outside market after green technology input under cap and trade policy.\",\n \"Title: Case-based reasoning classifier based on learning pseudo metric retrieval\\nYear: 2017\\n\\nAbstract: A learning pseudo metric case-based reasoning classification method is proposed.A new classifier is redesigned on the basis of the traditional CBR classifier.The algorithm of LPM-CBR has some anti-interference ability and good robustness.The LPM-based retrieval method can improve the quality and learning ability of CBR. In case-based reasoning (CBR) classification systems, the similarity metrics play a key role and directly affect the system's performance. Based on our previous work on the learning pseudo metrics (LPM), we propose a case-based reasoning method for pattern classification, where the widely used Euclidean distance is replaced by the LPM to measure the closeness between the target case and each source case. The same type of case as the target case can be retrieved and the category of the target case can be defined by using the majority of reuse principle. Experimental results over some benchmark datasets and a fault diagnosis of the Tennessee-Eastman (TE) process demonstrate that the proposed reasoning techniques in this paper can effectively improve the classification accuracy, and the LPM-based retrieval method can substantially improve the quality and learning ability of CBR classifiers.\",\n \"Title: Pulse Arrival Scheduling for Nanonetworks Under Limited IoT Access Bandwidth\\nYear: 2017\\n\\nAbstract: Electromagnetic Wireless Nano Sensor Networks (EM-WNSNs) with molecule-level sensing capacity benefit a wide range of applications that demand high resolution. To accommodate the potentially high data volume, small antenna size, and limited energy capacity, the high-speed TeraHertz (THz) pulses sparsely distributed over time are adopted for communications among nano devices. For EM-WNSNs connected to the Internet of Things (IoT), matching the throughput of nanonetworks and the IoT access bandwidth is significant for resource utilization efficiency. On the one hand, high throughput from nano sensors are limited by IoT access bandwidth, which results in low energy efficiency of EM-WNSNs when traffic regulation mechanisms are applied. On the other hand, low throughput from nanonetworks under utilize the allocated access bandwidth. To enable efficient data forwarding towards the access network, the EM-WNSNs throughput must match the IoT access bandwidth. For this purpose, the Adaptive Pulse Interval Scheduling (APIS) scheme, which schedules the arrival pattern of pulses transmitted by nano sinks based on the access bandwidth, is proposed for event-based EM-WNSNs. From performance evaluation and modelling, APIS implements data forwarding with high energy efficiency for nanonetworks and high bandwidth efficiency for IoT access networks. To the best of our knowledge, APIS is the first pulse level access scheduling solution for EM-WNSNs connected to the IoT.\",\n \"Title: On-Demand Probabilistic Polling for Nanonetworks Under Dynamic IoT Backhaul Network Conditions.\\nYear: 2017\\n\\nAbstract: Driven by the high sensing resolution provided by advanced nano technologies, electromagnetic-based wireless nano sensor networks (EM-WNSNs) operating in the terahertz (THz) band is becoming an integral part of the Internet of Things (IoT). Data acquisition for EM-WNSNs faces two challenges: 1) the dynamic IoT backhaul bandwidth and 2) THz channel conditions that jointly impact resource utilizatio...\",\n \"Title: Learning a fuzzy decision tree from uncertain data\\nYear: 2017\\n\\nAbstract: Uncertainty in data exists when the value of a data item is not a precise value, but rather by an interval data with a probability distribution function, or a probability distribution of multiple values. Since there are intrinsic differences between uncertain and certain data, it is difficult to deal with uncertain data using traditional classification algorithms. Therefore, in this paper, we propose a fuzzy decision tree algorithm based on a classical ID3 algorithm, it integrates fuzzy set theory and ID3 to overcome the uncertain data classification problem. Besides, we propose a discretization algorithm that enables our proposed Fuzzy-ID3 algorithm to handle the interval data. Experimental results show that our Fuzzy-ID3 algorithm is a practical and robust solution to the problem of uncertain data classification and that it performs better than some of the existing algorithms.\",\n \"Title: Self-Adaptive Gravitational Search Algorithm With a Modified Chaotic Local Search.\\nYear: 2017\\n\\nAbstract: The gravitational search algorithm (GSA) has been proved to yield good performance in solving various optimization problems. However, it is inevitable to suffer from slow exploitation when solving complex problems. In this paper, a thorough empirical analysis of the GSA is performed, which elaborates the role of the gravitational parameter G in the optimization process of the GSA. The convergence speed and solution quality are found to be highly sensitive to the value of G. A self-adaptive mechanism is proposed to adjust the value of G automatically, aiming to maintain the balance of exploration and exploitation. To further improve the convergence speed of GSA, we also modify the classic chaotic local search and insert it into the optimization process of the GSA. Through these two techniques, the main weakness of GSA has been overcome effectively, and the obtained results of 23 benchmark functions confirm the excellent performance of the proposed method.\",\n \"Title: A Comprehensive Study Of Blind And Non-Blind Deconvolution Methods Applied To Spectrum Extraction\\nYear: 2017\\n\\nAbstract: Spectrum extraction which is applied to extract one-dimensional (1D) astronomical spectroscopy from two-dimensional (2D) multi-fiber spectrum images plays a key role in data processing of 2D optical fiber spectrum. In this paper, we have given a detailed comparison of spectrum extraction methods between the blind deconvolution and the non-blind deconvolution to find out their specialities. The simulated arc spectrum data is used in Comparative experiments. The results show that the blind deconvolution is better than the non-blind deconvolution not only at spectrum extraction result but also remarkably at signal noise ratio (SNR).\",\n \"Title: Linear-Complexity Stochastic Variational Bayes Inference For Slam\\nYear: 2017\\n\\nAbstract: The simultaneous localization and mapping (SLAM) problem is concerned with using sensor data to build an environmental map, while also localizing an autonomous agent within this map. Two approaches are currently prevalent (Bayesian filtering and graph-based optimization), however these both involve approximations and have the potential to be improved. In this paper, we propose novel high-performance SLAM algorithms derived from variational Bayes inference. By using mean-field type approximations, the resulting computational complexity is linear. We also add an empirical Bayes assumption to improve the flexibility of the inference. Experiments are conducted on both synthetic data and real RGB-D images. The proposed approach achieves 42% average error reduction in all scenarios on synthetic data, and 26% average error reduction on real images (with respect to two other baseline algorithms).\",\n \"Title: Noncontact Human-Machine Interface With Planar Probing Coils in a Differential Sensing Architecture.\\nYear: 2018\\n\\nAbstract: This paper presents a noncontact human-machine interface which is capable of sensing and indicating the position of a human hand that is approaching a probing coil. High sensitivity is achieved by utilizing a structure including two oscillators and a mixer to compare and extract the electromagnetic shift between two probing coils. The probing coils chosen in this system have a planar structure and...\",\n \"Title: An Incremental Dual nu-Support Vector Regression Algorithm.\\nYear: 2018\\n\\nAbstract: Support vector regression (SVR) has been a hot research topic for several years as it is an effective regression learning algorithm. Early studies on SVR mostly focus on solving large-scale problems. Nowadays, an increasing number of researchers are focusing on incremental SVR algorithms. However, these incremental SVR algorithms cannot handle uncertain data, which are very common in real life because the data in the training example must be precise. Therefore, to handle the incremental regression problem with uncertain data, an incremental dual nu-support vector regression algorithm (dual-v-SVR) is proposed. In the algorithm, a dual-v-SVR formulation is designed to handle the uncertain data at first, then we design two special adjustments to enable the dual-v-SVR model to learn incrementally: incremental adjustment and decremental adjustment. Finally, the experiment results demonstrate that the incremental dual-v-SVR algorithm is an efficient incremental algorithm which is not only capable of solving the incremental regression problem with uncertain data, it is also faster than batch or other incremental SVR algorithms.\",\n \"Title: TTL-Based Efficient Forwarding for Nanonetworks With Multiple Coordinated IoT Gateways.\\nYear: 2018\\n\\nAbstract: Electromagnetic-based wireless nanosensor networks (EM-WNSNs) working in the terahertz (THz) band are developing fast because of the high sensing resolution that benefits a wide range of applications. In EM-WNSNs, nano-sinks that aggregate data from nanosensors to the Internet of Things (IoT) gateway collectively form a backhaul tier of EM-WNSNs. Unlike the data tier composed of densely deployed n...\",\n \"Title: A 16 MHz, 59.2 ppm/°C CMOS DLL-Assisted VCO with Improved Frequency Stability Towards Single Chip Wireless IOT\\nYear: 2016\\n\\nAbstract: A 16 MHz, highly stable voltage controlled oscillator (VCO) is reported in this paper. The proposed VCO consists of three cross-coupled RC stages, and is fully compatible with standard CMOS process. A positively biased PN junction with negative temperature coefficient is incorporated in the design to compensate frequency drift. In addition, a delay locked loop (DLL) directly following the VCO is utilized to further improve the output stability caused by temperature variations. The designed circuit was implemented using CMOS 0.18 mu m technology, and was validated through experiments. Measurement results show that the DLL-assisted VCO output variation across the 25 similar to 120 A degrees C temperature range is less than 0.56 %, corresponding to 59.2 ppm/A degrees C. It also shows that the output standard deviation of the DLL-assisted VCO is only 6.816 KHz, similar to 16.6 % better compared with the same VCO without DLL's assistance.\",\n \"Title: Multi-Gateway Polling for Nanonetworks under Dynamic IoT Backhaul Bandwidth\\nYear: 2018\\n\\nAbstract: As an emerging part of the Internet of Things (IoT), Electromagnetic-based Wireless NanoSensor Networks (EM-WNSNs) working in the TeraHertz (THz) band are envisaged to enable applications that demand high sensing resolution. For the high-speed nanonetworks deployed for time critical applications, the limited IoT backhaul bandwidth of the existing infrastructure becomes the bottleneck that deteriorates resource utilization efficiency. On the one hand, the bandwidth demand exceeding the supply results in unnecessary energy consumption on nano-devices due to the overdue data discarded. On the other hand, the excess supply of bandwidth reduces the bandwidth efficiency. To address this problem, the On-demand Efficient (OE) polling and On-demand Probabilistic (OP) polling were proposed. Nevertheless, the existing solutions only apply to the single-gateway scenario whereas deploying multiple gateways is required for achieving high data completeness and energy efficiency. Therefore, in this paper, we propose the Multi-gateway Probabilistic (MP) polling for the multi-gateway EMWNSNs. To achieve high bandwidth efficiency, in MP polling, one master gateway is selected for OP polling with the aggregated bandwidth that reduces the probabilistic uncertainty. Next, all gateways probabilistically receive packets using the bandwidth-based receiving windows. To the best of our knowledge, MP Polling is the first polling solution designed for the multi gateway EM-WNSNs under dynamic backhaul bandwidth.\",\n \"Title: Study on Security Technology of Internet of Things Based on Network Coding\\nYear: 2018\\n\\nAbstract: Along with the continuous progress of the information technology, Internet of Things is the inevitable way for realizing the fusion of communication and traditional network technology. Network coding, an important breakthrough in the field of communication, has many applied advantages in information network. This article analyses the eavesdropping problem of Internet of Things and presents an information secure network coding scheme against the eavesdropping adversaries. We show that, if the number of links the adversaries can eavesdrop on is less than the max-flow of a network, the proposed coding scheme not only `achieves the prefect information secure condition but also the max-flow of the network.\",\n \"Title: A CMOS Time-to-Digital Converter for Real-Time Optical Time-of-Flight Sensing System.\\nYear: 2018\\n\\nAbstract: The TOF method is the most popular and efficient way to extract depth information in an optical sensing system, and TDC is generally used to measure the round-trip delay. In this article, a TDC with ~40 ps measurement resolution and very large linear dynamic range is proposed for optical sensing applications. Referenced to a single 100 MHz clock, the TDC incorporates a DLL and a VDL loop to automa...\",\n \"Title: Design and Characteristic Analysis of Cross-Capacitance Fuel-Level Sensor.\\nYear: 2018\\n\\nAbstract: A cross-capacitance liquid level sensor is based on the principle of cross capacitance. This study designed a new single-tube cross-capacitance fuel-level sensor. The fuel-level measurement model is established for a single-tube cross-capacitive sensor, and the relationship between the measured liquid level and sensor output capacitance is derived. The characteristics of the sensor were tested experimentally. The experimental results demonstrate that the linearity error of the liquid-level sensor of the single-tube calculation for the spacecraft is +/- 0.48%, the repeatability error is +/- 0.47%, and the hysteresis error is +/- 0.68%. The cross-capacitive fuel-level sensor developed in this study can be used in the fuel tank of spacecrafts owing to its low weight and high precision.\",\n \"Title: Detecting and Segmenting White Blood Cells in Microscopy Images of Thin Blood Smears\\nYear: 2017\\n\\nAbstract: A malarial infection is diagnosed and monitored by screening microscope images of blood smears for parasite-infected red blood cells. Millions of blood slides are manually screened for parasites every year, which is a tedious and error-prone process, and which largely depends on the expertise of the microscopists. We have developed a software to perform this task on a smartphone, using machine learning and image analysis methods for counting infected red blood cells automatically. The method we implemented first needs to detect and segment red blood cells. However, the presence of white blood cells (WBCs) contaminates the red blood cell detection and segmentation process because WBCs can be miscounted as red blood cells by automatic cell detection methods. As a result, a preprocessing step for WBC elimination is essential. Our paper proposes a novel method for white blood cell segmentation in microscopic images of blood smears. First, a range filtering algorithm is used to specify the location of white blood cells in the image following a Chan- Vese level-set algorithm to estimate the boundaries of each white blood cell present in the image. The proposed segmentation algorithm is systematically tested on a database of more than 1300 thin blood smear images exhibiting approximately 1350 WBCs. We evaluate the performance of the proposed method for the two WBC detection and WBC segmentation steps by comparing the annotations provided by a human expert with the results produced by the proposed algorithm. Our detection technique achieves a 96.37 % overall precision, 98.37 % recall, and 97.36 % Fl-score. The proposed segmentation method grants an overall 82.28 % Jaccard Similarity Index. These results demonstrate that our approach allows us to filter out WBCs, which significantly improves the precision of the cell counts for malaria diagnosis.\",\n \"Title: A Unified Smart Chinese Medicine Framework for Healthcare and Medical Services.\\nYear: 2021\\n\\nAbstract: Smart Chinese medicine has emerged to contribute to the evolution of healthcare and medical services by applying machine learning together with advanced computing techniques like cloud computing to computer-aided diagnosis and treatment in the health engineering and informatics. Specifically, smart Chinese medicine is considered to have the potential to treat difficult and complicated diseases suc...\",\n \"Title: Parallel Parametric Linear Programming Solving, And Application To Polyhedral Computations\\nYear: 2019\\n\\nAbstract: Parametric linear programming is central in polyhedral computations and in certain control applications. We propose a task-based scheme for parallelizing it, with quasi-linear speedup over large problems.\",\n \"Title: Weighted total least-squares joint adjustment with weight correction factors\\nYear: 2019\\n\\nAbstract: A joint adjustment involves integrating different types of geodetic datasets, or multiple datasets of the same data type, into a single adjustment. This paper applies the weighted total least-squares (WTLS) principle to joint adjustment problems and proposes an iterative algorithm for WTLS joint (WTLS-J) adjustment with weight correction factors. Weight correction factors are used to rescale the weight matrix of each dataset while using the Helmert variance component estimation (VCE) method to estimate the variance components, since the variance components in the stochastic model are unknown. An affine transformation example is illustrated to verify the practical benefit and the relative computational efficiency of the proposed algorithm. It is shown that the proposed algorithm obtains the same parameter estimates as the Amiri-Simkooei algorithm in our example; however, the proposed algorithm has its own computational advantages, especially when the number of data points is large.\",\n \"Title: Weighted total least-squares joint adjustment with weight correction factors\\nYear: 2019\\n\\nAbstract: A joint adjustment involves integrating different types of geodetic datasets, or multiple datasets of the same data type, into a single adjustment. This paper applies the weighted total least-squares (WTLS) principle to joint adjustment problems and proposes an iterative algorithm for WTLS joint (WTLS-J) adjustment with weight correction factors. Weight correction factors are used to rescale the weight matrix of each dataset while using the Helmert variance component estimation (VCE) method to estimate the variance components, since the variance components in the stochastic model are unknown. An affine transformation example is illustrated to verify the practical benefit and the relative computational efficiency of the proposed algorithm. It is shown that the proposed algorithm obtains the same parameter estimates as the Amiri-Simkooei algorithm in our example; however, the proposed algorithm has its own computational advantages, especially when the number of data points is large.\",\n \"Title: Deep reinforcement learning with its application for lung cancer detection in medical Internet of Things\\nYear: 2019\\n\\nAbstract: Recently, deep reinforcement learning has achieved great success by integrating deep learning models into reinforcement learning algorithms in various applications such as computer games and robots. Specially, it is promising for computer-aided diagnosis and treatment to combine deep reinforcement learning with medical big data generated and collected from medical Internet of Things. In this paper, we focus on the potential of the deep reinforcement learning for lung cancer detection as many people are suffering from the lung tumor and about 1.8 million patients died from lung cancer in 2018. Early detection and diagnosis of lung tumor can significantly improve the treatment effect and prolong survival. In this work, we present several representative deep reinforcement learning models that are potential to use for lung cancer detection. Furthermore, we summarize the common types of lung cancer and the main characteristics of each type. Finally, we point out the open challenges and possible future research directions of applying deep reinforcement learning to lung cancer detection, which is expected to promote the evolution of smart medicine with medical Internet of Things.\",\n \"Title: Deep Learning Models For Diagnosing Spleen And Stomach Diseases In Smart Chinese Medicine With Cloud Computing\\nYear: 2021\\n\\nAbstract: Cloud computing is significantly contributing to the development of smart Chinese medicine. The diagnosis and treatment of spleen and stomach diseases has been arousing great interest in smart Chinese medicine with cloud computing since many persons are suffering from spleen and stomach diseases. Currently, spleen and stomach diseases present some new characteristics with the dramatic changes in natural climate, social environment, and human living habits. Recently, deep learning, together with cloud computing techniques, has successfully used in medical image analysis and therefore it is the most promising model for diagnosing spleen and stomach disease in smart Chinese medicine. In this paper, we present a survey on deep learning models in medical image analysis for computer-aided diagnosis in modern medicine. Afterwards, we summarize the syndrome types of spleen and stomach diseases and furthermore analyze the causes and pathogenesis for each syndrome. Finally, we discuss the open challenges and research directions of deep learning models applicable to the computer-aided diagnosis of spleen and stomach diseases, which is expected to contribute to the development of smart Chinese medicine with cloud computing.\",\n \"Title: Mathematical modeling of yard template regeneration for multiple container terminals\\nYear: 2019\\n\\nAbstract: As a tactical-level plan, the yard template determines the space allocation in a container terminal yard for all the arriving shipping liners. Generally speaking, the yard template will not change and it may last a matter of years. However, it has to be changed to response to the alteration of shipping liner. This paper investigates the problem of yard template regeneration for container port, which contains multiple container terminals. Firstly, the concept of yard template regeneration as well as the main influencing factors is proposed. Secondly, a multiple-objective mixed integer programming model is formulated which fully considering the minimum transportation cost, minimum template disturbance and maximum space utilization. Moreover, a case study is conducted to intuitively illustrate the regeneration problem of yard template. Finally, performance analysis and sensitivity analysis are performed to validate the effectiveness of the model.\",\n \"Title: Efficient Stochastic Subgradient Descent Algorithms For High-Dimensional Semi-Sparse Graphical Model Selection\\nYear: 2019\\n\\nAbstract: We consider the structure learning problem of Gaussian graphical models when the underlying graph is semi-sparse. More specifically, we assume that the number of edges in the graph grows quadratically with the dimension P. Similar to the case of sparse graphs, the problem is formulated as maximizing the data log-likelihood with an l(1) norm penalty on the precision matrix (the inverse covariance matrix) that promotes sparsity. We notice that the time complexity of all existing methods is at least O(P-3) under the scenario of semi-sparse graphs, thus severely hindering their applications to high-dimensional data. By contrast, the time complexity of the proposed method is only O(P-2) with the help of stochastic gradients. We prove the convergence of the proposed algorithm. Numerical results show that the computational time of the proposed method is shorter than that of the state-of-the-art methods when the graph is semi-sparse.\",\n \"Title: The Verified Polyhedron Library: an Overview\\nYear: 2018\\n\\nAbstract: The Verified Polyhedra Library operates upon a constraint-only representation of convex polyhedra and provides all common operations (image, pre-image, projection, convex hull, widening, inclusion and equality tests. . . ). Optionally, the soundness of the results is checked by a layer certified in Coq.\",\n \"Title: A Bayesian Method For Dynamic Origin-Destination Demand Estimation Synthesizing Multiple Sources Of Data\\nYear: 2021\\n\\nAbstract: In this paper a Bayesian method is proposed to estimate dynamic origin-destination (O-D) demand. The proposed method can synthesize multiple sources of data collected by various sensors, including link counts, turning movements at intersections, flows, and travel times on partial paths. Time-dependent demand for each O-D pair at each departure time is assumed to satisfy the normal distribution. The connections among multiple sources of field data and O-D demands for all departure times are established by their variance-covariance matrices. Given the prior distribution of dynamic O-D demands, the posterior distribution is developed by updating the traffic count information. Then, based on the posterior distribution, both point estimation and the corresponding confidence intervals of O-D demand variables are estimated. Further, a stepwise algorithm that can avoid matrix inversion, in which traffic counts are updated one by one, is proposed. Finally, a numerical example is conducted on Nguyen-Dupuis network to demonstrate the effectiveness of the proposed Bayesian method and solution algorithm. Results show that the total O-D variance is decreasing with each added traffic count, implying that updating traffic counts reduces O-D demand uncertainty. Using the proposed method, both total error and source-specific errors between estimated and observed traffic counts decrease by iteration. Specifically, using 52 multiple sources of traffic counts, the relative errors of almost 50% traffic counts are less than 5%, the relative errors of 85% traffic counts are less than 10%, the total error between the estimated and \\\"true\\\" O-D demands is relatively small, and the O-D demand estimation accuracy can be improved by using more traffic counts. It concludes that the proposed Bayesian method can effectively synthesize multiple sources of data and estimate dynamic O-D demands with fine accuracy.\",\n \"Title: Research on economic benefits of multi-city logistics development based on data-driven analysis\\nYear: 2021\\n\\nAbstract: This study aims to measure the logistics economic efficiency of major first-tier cities in China and propose the interactive development plan of the green logistics industry based on the division of the urban agglomeration. In this study, the evaluation system for the logistics input and economic output of urban agglomerations is firstly established based on data-driven analytics, and a green logistics economic efficiency model using the dataset from 2008 to 2017 is constructed to estimate the input–output efficiency, development trend, and spatial differentiation of urban agglomerations comprehensively. Finally, the Shapley value method is adopted to obtain the specific distribution plan of logistics investment. The results show that the logistics economic efficiency of the 9 major urban agglomerations is all greater than 1 under the constant returns-to-scale (CRS) hypothesis while the average logistics economic efficiency of Pearl River Delta region, Chengdu-Chongqing region, and Shandong Peninsula region is significantly less than 1 under the medium returns-to-scale (MRS) hypothesis. The comprehensive input–output efficiency of five out of 9 major Chinese urban agglomerations showed a downward trend, with the highest declining rate of 5.9% in the Yangtze River Delta urban agglomeration. The urban agglomeration with the highest increase rate in input–output efficiency from 2013 to 2017 is the Chengdu-Chongqing region, which reached 3.97%.\",\n \"Title: Laser Induced Graphene Patterns On A Thin Polyimide Film Via A Cooling Plate\\nYear: 2021\\n\\nAbstract: Laser induced graphene technology on a polyimide (PI) film substrate for supercapacitors, flexible sensors and heaters, has been a hot topic due to its fast fabrication speed and 3D controllable microstructure formation. However, the thin PI film will suffer burnthrough of the film under the required high energy density to form graphene. Herein, we introduced an auxiliary cooling semiconductor plate beneath the PI substrate to decrease the temperature of the substrate to reduce the burnt thickness. Experiment results showed that the burnt thickness will decrease to about 33.39 mu m for -2 degrees C on the thin film with thickness about 12 mu m and the value of resistance can still be kept at 8.33 k Omega. The effects of the scanning speed and power on the size of the wire also discussed. Therefore, such method may open a way to fabricate graphene patterns on thin films with thickness less than a few micrometers, which will play an important role in applications including electronic skins and multi-layer flexible plastic circuits.\",\n \"Title: Salient Region Guided Blind Image Sharpness Assessment\\nYear: 2021\\n\\nAbstract: Salient regions provide important cues for scene understanding to the human vision system. However, whether the detected salient regions are helpful in image blur estimation is unknown. In this study, a salient region guided blind image sharpness assessment (BISA) framework is proposed, and the effect of the detected salient regions on the BISA performance is investigated. Specifically, three salient region detection (SRD) methods and ten BISA models are jointly explored, during which the output saliency maps from SRD methods are re-organized as the input of BISA models. Consequently, the change in BISA metric values can be quantified and then directly related to the difference in BISA model inputs. Finally, experiments are conducted on three Gaussian blurring image databases, and the BISA prediction performance is evaluated. The comparison results indicate that salient region input can help achieve a close and sometimes superior performance to a BISA model over the whole image input. When using the center region input as the baseline, the detected salient regions from the saliency optimization from robust background detection (SORBD) method lead to consistently better score prediction, regardless of the BISA model. Based on the proposed hybrid framework, this study reveals that saliency detection benefits image blur estimation, while how to properly incorporate SRD methods and BISA models to improve the score prediction will be explored in our future work.\",\n \"Title: Trajectory Planning for Collaborative Transportation by Tethered Multi-UAVs\\nYear: 2021\\n\\nAbstract: Collaborative transportation has been widely studied due to its high efficiency, and interesting research problems., specifically in trajectory planning. In this paper, a new trajectory planning scheme for collaborative transportation by tethered multi-UAVs is proposed to avoid obstacles. Firstly, the dynamics and configuration of the system is analyzed to derive the tethered force acting on each UAV, and define the angle between the rope and the vertical direction is calculated. Then the kinodynamic path search method is used to search an initial trajectory of the payload, and the initial trajectory of each UAV is solved. Finally, nonlinear optimization is used to optimize the trajectory of each UAV and the payload to achieve the effect of obstacle avoidance. Both numerical simulations and practical experiments are completed to verify the feasibility and effectiveness of the proposed planning scheme.\",\n \"Title: Progressive Diversified Augmentation for General Robustness of DNNs: A Unified Approach\\nYear: 2021\\n\\nAbstract: Adversarial images are imperceptible perturbations to mislead deep neural networks (DNNs), which have attracted great attention in recent years. Although several defense strategies achieved encouraging robustness against adversarial samples, most of them still failed to consider the robustness on common corruptions (e.g. noise, blur, and weather/digital effects). To address this problem, we propose a simple yet effective method, named Progressive Diversified Augmentation (PDA), which improves the robustness of DNNs by progressively injecting diverse adversarial noises during training. In other words, DNNs trained with PDA achieve better general robustness against both adversarial attacks and common corruptions than other strategies. In addition, PDA also enjoys the advantages of spending less training time and keeping high standard accuracy on clean examples. Further, we theoretically prove that PDA can control the perturbation bound and guarantee better robustness. Extensive results on CIFAR-10, SVHN, ImageNet, CIFAR-10-C and ImageNet-C have demonstrated that PDA comprehensively outperforms its counterparts on the robustness against adversarial examples and common corruptions as well as clean images. More experiments on the frequency-based perturbations and visualized gradients further prove that PDA achieves general robustness and is more aligned with the human visual system.\",\n \"Title: How Does Social Behavior Affect Your Password?\\nYear: 2021\\n\\nAbstract: A password is an important method of identity authentication, so there are endless research attempts on passwords, but most of them are based on different languages and technologies. As far as we know, no one has studied the influence of one's social behavior (e.g., religious belief) on passwords. Based on this, we first study the influence of religion on the generation of user passwords. Taking C...\",\n \"Title: Further studies on numerical instabilities of Godunov-type schemes for strong shocks\\nYear: 2021\\n\\nAbstract: In this paper, continuous research is undertaken to explore the underlying mechanism of numerical shock instabilities of Godunov-type schemes for strong shocks. By conducting dissipation analysis of Godunov-type schemes and a sequence of numerical experiments, we are able to clarify that the instability may be attributed to insufficient entropy production inside the numerical shock structure. As a result, a general entropy-control technique for improving the robustness of various Godunov-type schemes at strong shocks is developed. It plays a part in guaranteeing that enough entropy is produced inside the numerical shock structure. Furthermore, such a modified approach does not introduce any additional numerical dissipation on linear degenerate waves to suppress the shock instability. Numerical results that are obtained for various test cases indicate that the proposed methods have a good performance in terms of accuracy and robustness.\",\n \"Title: An Online Robust Support Vector Regression for Data Streams\\nYear: 2022\\n\\nAbstract: Since support vector regression (SVR) is a flexible regression algorithm, its computational complexity does not depend on the dimensionality of the input space, and it has excellent generalization capability. However, a central assumption with SVRs is that all the required data is available at the time of construction, which means these algorithms cannot be used with data streams. Incremental SVR ...\",\n \"Title: Distributed cooperative guidance law for multiple missiles with input delay and topology switching\\nYear: 2021\\n\\nAbstract: This paper considers the simultaneous attack of a stationary target by multiple missiles. A novel fixed-time distributed guidance law based on the proportional navigation (PN) guidance law is designed by integrating a consistent control technique into the guidance strategy. This guarantees that the time-to-go of the missile becomes consistent. The guidance law adopts a discrete design, and a compensation item driven by normal acceleration is added to tangential acceleration. This eliminates the potential singularity problem when the heading angle is zero before the consistency is obtained, and thus the multiple missile system still converges in fixed time. In addition, the proposed guidance law can be applied to both undirected and directed graphs. Furthermore, two improved guidance laws are proposed to improve the robustness of the system against adverse effects caused by input delays and topology switching failures and to provide a theoretical proof. Finally, a simulation is used to verify the performance of the distributed guidance law and its robustness against the above failures.\",\n \"Title: Identifying Drug-Resistant Tuberculosis in Chest Radiographs: Evaluation of CNN Architectures and Training Strategies\\nYear: 2021\\n\\nAbstract: Tuberculosis (TB) is a serious infectious disease that mainly affects the lungs. Drug resistance to the disease makes it more challenging to control. Early diagnosis of drug resistance can help with decision making resulting in appropriate and successful treatment. Chest X-rays (CXRs) have been pivotal to identifying tuberculosis and are widely available. In this work, we utilize CXRs to distinguish between drug-resistant and drug-sensitive tuberculosis. We incorporate Convolutional Neural Network (CNN) based models to discriminate the two types of TB, and employ standard and deep learning based data augmentation methods to improve the classification. Using labeled data from NIAID TB Portals and additional non-labeled sources, we were able to achieve an Area Under the ROC Curve (AUC) of up to 85% using a pretrained InceptionV3 network.\",\n \"Title: Secure typing via BCI system with encrypted feedback\\nYear: 2021\\n\\nAbstract: Information transmission security is an important issue in many scenarios such as password input. Traditional approaches such as typing or voice input are prone to peep, leading to a risk of information leakage. Brain computer interface (BCI) can read information directly from the brain, which is confidential inherently, thus it may be an ideal way for secure information input. This paper proposes a novel BCI-based secure input approach with encrypted feedback. The encrypted feedback is specially designed to notify users and confuse peepers at the same time. We give the theoretical guarantee of accuracy and evaluate the system with both simulation and experiments. The results show that our method can transmit messages effectively.\",\n \"Title: CvT-ASSD: Convolutional vision-Transformer Based Attentive Single Shot MultiBox Detector\\nYear: 2021\\n\\nAbstract: Due to the success of Bidirectional Encoder Representations from Transformers (BERT) in natural language process (NLP), the multi-head attention transformer has been more and more prevalent in computer-vision researches (CV). However, it still remains a challenge for researchers to put forward complex tasks such as vision detection and semantic segmentation. Although multiple Transformer-Based architectures like DETR and ViT-FRCNN have been proposed to complete object detection task, they inevitably decreases discrimination accuracy and brings down computational efficiency caused by the enormous learning parameters and heavy computational complexity incurred by the traditional self-attention operation. In order to alleviate these issues, we present a novel object detection architecture, named Convolutional vision Transformer-Based Attentive Single Shot MultiBox Detector (CvT-ASSD), that built on the top of Convolutional vision Transormer (CvT) with the efficient Attentive Single Shot MultiBox Detector (ASSD). We provide comprehensive empirical evidence showing that our model CvT-ASSD can leads to good system efficiency and performance while being pretrained on large-scale detection datasets such as PASCAL VOC and MS COCO. Code has been released on public github repository at https://github.com/albert-jin/CvT-ASSD.\",\n \"Title: Efficient Variational Bayes Learning of Graphical Models With Smooth Structural Changes\\nYear: 2023\\n\\nAbstract: Estimating a sequence of dynamic undirected graphical models, in which adjacent graphs share similar structures, is of paramount importance in various social, financial, biological, and engineering systems, since the evolution of such networks can be utilized for example to spot trends, detect anomalies, predict vulnerability, and evaluate the impact of interventions. Existing methods for learning dynamic graphical models require the tuning parameters that control the graph sparsity and the temporal smoothness to be selected via brute-force grid search. Furthermore, these methods are computationally burdensome with time complexity \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$\\\\mathcal {O}(NP^3)$</tex-math></inline-formula>\\n for \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$P$</tex-math></inline-formula>\\n variables and \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$N$</tex-math></inline-formula>\\n time points. As a remedy, we propose a low-complexity tuning-free Bayesian approach, named BASS. Specifically, we impose temporally dependent spike and slab priors on the graphs such that they are sparse and varying smoothly across time. An efficient variational inference algorithm based on natural gradients is then derived to learn the graph structures from the data in an automatic manner. Owing to the pseudo-likelihood and the mean-field approximation, the time complexity of BASS is only \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$\\\\mathcal {O}(NP^2)$</tex-math></inline-formula>\\n. To cope with the local maxima problem of variational inference, we resort to simulated annealing and propose a method based on bootstrapping of the observations to generate the annealing noise. We provide numerical evidence that BASS outperforms existing methods on synthetic data in terms of structure estimation, while being more efficient especially when the dimension \\n<inline-formula><tex-math notation=\\\"LaTeX\\\">$P$</tex-math></inline-formula>\\n becomes high. We further apply the approach to the stock return data of 78 banks from 2005 to 2013 and find that the number of edges in the financial network as a function of time contains three peaks, in coincidence with the 2008 global financial crisis and the two subsequent European debt crisis. On the other hand, by identifying the frequency-domain resemblance to the time-varying graphical models, we show that BASS can be extended to learning frequency-varying inverse spectral density matrices, and further yields graphical models for multivariate stationary time series. As an illustration, we analyze scalp EEG signals of patients at the early stages of Alzheimer’s disease (AD) and show that the brain networks extracted by BASS can better distinguish between the patients and the healthy controls.\",\n \"Title: Entity Relation Fusion for Real-Time One-Stage Referring Expression Comprehension\\nYear: 2021\\n\\nAbstract: ABSTRACTReferring Expression Comprehension (REC) is the task of grounding object which is referred by the language expression. Previous one-stage REC methods usually use one single language feature vector to represent the whole query for grounding and no reasoning between different objects is performed despite the rich relation cues of objects contained in the language expression, which depresses their grounding accuracy. Additionally, these methods mostly use the feature pyramid networks for multi-scale visual object feature extraction but ground on different feature layers separately, neglecting the connections between objects with different scales. To address these problems, we propose a novel one-stage REC method, i.e. the Entity Relation Fusion Network (ERFN) to locate referred object by relation guided reasoning on different objects. In ERFN, instead of grounding objects at each layer separately, we propose a Language Guided Multi-Scale Fusion (LGMSF) model to utilize language to guide the fusion of representations of objects with different scales into one feature map.For modeling connections between different objects, we design a Relation Guided Feature Fusion (RGFF) model that extracts entities in the language expression to enhance the referred entity feature in the visual object feature map, and further extracts relations to guide object feature fusion based on the self-attention mechanism. Experimental results show that our method is competitive with the state-of-the-art one-stage and two-stage REC methods, and can also keep inferring in real time.\",\n \"Title: Nonlinear Noise Cleaning in Gravitational-Wave Detectors With Convolutional Neural Networks.\\nYear: 2022\\n\\nAbstract: Currently, the sub-60 Hz sensitivity of gravitational-wave (GW) detectors like Advanced LIGO (aLIGO) is limited by the control noises from auxiliary degrees of freedom which nonlinearly couple to the main GW readout. One promising way to tackle this challenge is to perform nonlinear noise mitigation using convolutional neural networks (CNNs), which we examine in detail in this study. In many cases, the noise coupling is bilinear and can be viewed as a few fast channels' outputs modulated by some slow channels. We show that we can utilize this knowledge of the physical system and adopt an explicit \\\"slow×fast\\\" structure in the design of the CNN to enhance its performance of noise subtraction. We then examine the requirements in the signal-to-noise ratio (SNR) in both the target channel (i.e., the main GW readout) and in the auxiliary sensors in order to reduce the noise by at least a factor of a few. In the case of limited SNR in the target channel, we further demonstrate that the CNN can still reach a good performance if we use curriculum learning techniques, which in reality can be achieved by combining data from quiet times and those from periods with active noise injections.\",\n \"Title: Pyraformer: Low-Complexity Pyramidal Attention for Long-Range Time Series Modeling and Forecasting\\nYear: 2022\\n\\nAbstract: Accurate prediction of the future given the past based on time series data is of paramount importance, since it opens the door for decision making and risk management ahead of time. In practice, the challenge is to build a flexible but parsimonious model that can capture a wide range of temporal dependencies. In this paper, we propose Pyraformer by exploring the multiresolution representation of the time series. Specifically, we introduce the pyramidal attention module (PAM) in which the inter-scale tree structure summarizes features at different resolutions and the intra-scale neighboring connections model the temporal dependencies of different ranges. Under mild conditions, the maximum length of the signal traversing path in Pyraformer is a constant (i.e., $\\\\mathcal O(1)$) with regard to the sequence length $L$, while its time and space complexity scale linearly with $L$. Extensive numerical results show that Pyraformer typically achieves the highest prediction accuracy in both single-step and long-range forecasting tasks with the least amount of time and memory consumption, especially when the sequence is long.\",\n \"Title: Quantitative Analysis of Structural Parameters Importance of Helical Temperature Microfiber Sensor by Artificial Neural Network\\nYear: 2021\\n\\nAbstract: With the assistance of the evaluation algorithms based on the well-performed backpropagation neural network (BPNN), we quantitatively analyze the importance of the structural parameters of the supported helical microfiber (HMF) temperature sensor. The relative output intensities of HMF sensor at different temperatures are predicted by the BPNN with the HMF's structural parameters as the input variables. The best-forecasted performance is obtained by the BPNN with one hidden layer of ten neurons. Compared with the actual values, the root-mean-square error (RMSE) and the correlation coefficient of the predicted values are 9.7 x 10(-3) dB and 99.84%, respectively. Based on the BPNN with precise prediction, the backward stepwise elimination and the holdback input randomization methods are used to quantitatively discuss the influence of the structural parameters on the output intensity of the HMF. The relative importance from high to low is the helical length (similar to 38%), microfiber diameter (similar to 27%), helical angle (similar to 25%), and cone angle (similar to 10%). The importance of four geometric parameters obtained by the two methods is ranked the same. Quantitative analysis of structural parameters relying on the well-predicted BPNN can give basic information on the structural characteristics of the HMF sensor, which helps to optimize the structure design of the optical sensors based on micro/nanofiber and provides a powerful guarantee for its practical application.\",\n \"Title: Remote Sensing Image Land Classification Based on Deep Learning\\nYear: 2021\\n\\nAbstract: Aiming at the problems of high-resolution remote sensing images with many features and low classification accuracy using a single feature description, a remote sensing image land classification model based on deep learning from the perspective of ecological resource utilization is proposed. Firstly, the remote sensing image obtained by Gaofen-1 satellite is preprocessed, including multispectral data and panchromatic data. Then, the color, texture, shape, and local features are extracted from the image data, and the feature-level image fusion method is used to associate these features to realize the fusion of remote sensing image features. Finally, the fused image features are input into the trained depth belief network (DBN) for processing, and the land type is obtained by the Softmax classifier. Based on the Keras and TensorFlow platform, the experimental analysis of the proposed model shows that it can clearly classify all land types, and the overall accuracy, F1 value, and reasoning time of the classification results are 97.86%, 87.25%, and 128 ms, respectively, which are better than other comparative models.\",\n \"Title: Underground Object Classification Using Deep 3-D Convolutional Networks and Multiple Mirror Encoding for GPR Data\\nYear: 2022\\n\\nAbstract: Ground-penetrating radar (GPR) is an effective tool for underground object detection, but its data interpretation remains a great challenge. In this letter, we propose a novel underground object classification algorithm using deep 3-D convolutional networks (C3D) and multiple mirror encoding (MME) for 3-D GPR data. Although deep learning technique has been applied to interpret the GPR data, most of the existing methods are based on GPR B-scans and have a relatively low accuracy since the reflections from various subsurface targets present similar hyperbolic patterns in B-scans. To improve the classification accuracy, we use 3-D GPR data as training data for C3D to capture the spatio-temporal features between parallel B-scans. Since 3-D GPR data including single object has different sizes in consideration of actual sizes of objects, they are rearranged by the MME method to enhance spatio-temporal features, as well as to satisfy the requirement of the network input. Experimental results demonstrate that the proposed method outperforms the state-of-the-art B-scan-based methods.\",\n \"Title: Semi-Supervised Cross-Subject Emotion Recognition Based on Stacked Denoising Autoencoder Architecture Using a Fusion of Multi-Modal Physiological Signals\\nYear: 2022\\n\\nAbstract: In recent decades, emotion recognition has received considerable attention. As more enthusiasm has shifted to the physiological pattern, a wide range of elaborate physiological emotion data features come up and are combined with various classifying models to detect one's emotional states. To circumvent the labor of artificially designing features, we propose to acquire affective and robust representations automatically through the Stacked Denoising Autoencoder (SDA) architecture with unsupervised pre-training, followed by supervised fine-tuning. In this paper, we compare the performances of different features and models through three binary classification tasks based on the Valence-Arousal-Dominance (VAD) affection model. Decision fusion and feature fusion of electroencephalogram (EEG) and peripheral signals are performed on hand-engineered features; data-level fusion is performed on deep-learning methods. It turns out that the fusion data perform better than the two modalities. To take advantage of deep-learning algorithms, we augment the original data and feed it directly into our training model. We use two deep architectures and another generative stacked semi-supervised architecture as references for comparison to test the method's practical effects. The results reveal that our scheme slightly outperforms the other three deep feature extractors and surpasses the state-of-the-art of hand-engineered features.\",\n \"Title: General Mass Property Measurement Equipment for Large-Sized Aircraft\\nYear: 2022\\n\\nAbstract: The accurate measurement of aircraft mass properties, such as the mass, centroid, and moment of inertia (MOI), plays a key role in the precise control of aircraft. In order to obtain high-precision information on the parameters of the mass, centroid, and MOI of an aircraft using a single instrument, an integrated mass property measurement system was developed in this study by analyzing and comparing the latest technologies, especially the function-switching device, which switches the measurement states between the center of mass and the MOI. The purpose of mass property measurement was achieved through single clamping. In addition, the system has strong versatility and expansion and can be used with different tooling or adapter rings to measure the mass properties of aircraft with different shapes. In this paper, the main mechanical structure of the measurement system, the measurement method of relevant mass parameters, and the solution method of the transformation matrix are introduced, and the standard parts and the aircraft were verified experimentally. The test results showed that the mass measurement accuracy was 0.03%, the centroid measurement error was within +/- 0.2 mm, and the measurement accuracy of the MOI was within 0.2%, all of which meet the high-precision measurement requirements for the mass properties.\",\n \"Title: Deep Learning-Based Cell Detection and Extraction in Thin Blood Smears for Malaria Diagnosis\\nYear: 2021\\n\\nAbstract: Malaria is a major health threat caused by Plasmod-ium parasites that infect the red blood cells. Two predominant types of Plasmodium parasites are Plasmodium vivax (P. vivax) and Plasmodium falciparum (P. falciparum). Diagnosis of malaria typically involves visual microscopy examination of blood smears for malaria parasites. This is a tedious, error-prone visual inspection task requiring microsco...\",\n \"Title: Automated Drug-Resistant TB Screening: Importance of Demographic Features and Radiological Findings in Chest X-Ray\\nYear: 2021\\n\\nAbstract: Tuberculosis (TB) is a global disease caused by the bacillus Mycobacterium tuberculosis. In recent years, great progress has been made in care and control of drug-sensitive TB, whereas drug-resistant TB continues to be a worldwide public health problem that takes a heavy toll on both patients and the health care system. Early detection of drug resistance during a patient's first visit is very impo...\",\n \"Title: Self-Distilled Supervised Contrastive Learning for diagnosis of breast cancers with histopathological images\\nYear: 2022\\n\\nAbstract: Convolutional neural networks (CNN) and its variants have been widely used for developing the histopathological image based computer-aided diagnosis (CAD). However, the annotated data are scarce in clinical practice, and limited training samples generally cannot well train the CNN model, resulting in degraded predictive performance. To this end, we propose a novel Self-Distilled Supervised Contrastive Learning (SDSCL) algorithm to improve the diagnostic performance of a CNN-based CAD for breast cancer. In particular, the original histopathological images are first decomposed into H and E stain views, which are served as the augmented sample pairs in the supervised contrastive learning (SCL). Due to the complementary characteristic of the two stain views, this data-driven SCL guide the CNN model to efficiently learn the discriminative features, alleviating the problem of small sample size. Furthermore, self-distillation is embedded into the SCL framework, in which the CNN model jointly distills itself and conducts SCL to further improve feature representation. The proposed SDSCL is evaluated on two public breast histopathological datasets, which outperforms all the compared algorithms. Its average classification accuracy, precision, recall, and F1 scores are 94.28%, 94.64%, 94.58%, 94.34%, respectively, on Bioimaging dataset, and 80.44%, 81.92%, 80.57%, 80.10% on Databiox dataset. The experimental results on two datasets indicate that SDSCL has the potential for the histopathological image based CAD.\",\n \"Title: An immersed boundary method with implicit body force for compressible viscous flow\\nYear: 2022\\n\\nAbstract: We present a new immersed boundary method for the simulation of compressible viscous flow. The method is based on the singular source approach where the immersed boundary adds surface singularities to the governing equations. The strengths of the surface singularities are treated as algebraic variables under the framework of differential-algebraic equations and are implicitly calculated to enforce the corresponding boundary conditions. Discrete delta functions are used to approximate the surface singularities in the Eulerian grid and interpolate variables back to the surface mesh. A half-explicit Runge-Kutta method is used to achieve desired temporal accuracy. The method has been generalized from the well-known no-slip and isothermal condition to stress and heat flux conditions. The latter necessitates the introduction of further singularities in the stresses and heat flux, which is a new feature of the formulation. Furthermore, the approach has been extended to porous surfaces. The method is also applicable to flow-structure interaction problems. Two- and three-dimensional numerical tests are carried out to demonstrate accuracy. The results are compared with previous numerical and experimental studies or analytical solutions. Finally, a fully three-dimensional fluid-structure interaction simulation of a subsonic parachute is showcased to demonstrate applicability to a real problem.\",\n \"Title: On the Bilevel Optimization for Remapping Virtual Networks in an HOE-DCN\\nYear: 2022\\n\\nAbstract: Hybrid optical/electrical datacenter network (HOE-DCN) uses the inter-rack networks that consist of both electrical Ethernet switches and optical cross-connects (OXCs), for better cost-efficiency and scalability. Meanwhile, to provision dynamic network services well, the operator of an HOE-DCN needs to deploy virtual networks (VNTs) and remap them adaptively. Therefore, this work studies the problem of VNT remapping in an HOE-DCN from a novel perspective, i.e., the remapping schemes should be optimized for not only the network status after the remapping but also the transition to realize it. Specifically, we model this problem as a bilevel optimization, where the upper-level optimization aims at selecting proper virtual machines (VMs) to migrate such that the estimated latency of VM migration can be minimized, and the lower-level optimization determines the actual scheme of VNT remapping for minimizing the number of resource hot-spots. We first formulate a bilevel mixed integer linear programming (BMILP) model for the bilevel optimization, and then propose a polynomial time algorithm based on enumeration to solve it approximately. Extensive simulations verify the effectiveness of our proposal.\",\n \"Title: Nucleus image segmentation method based on GAN and FCN model\\nYear: 2022\\n\\nAbstract: The study aims at the problems of rough edges and low accuracy in processing cell nucleus image segmentation in existing image segmentation methods. The use of a generative adversarial network (GAN) and a fully convolutional network (FCN) model to segment cell nuclei is suggested. First, the FCN model is used to perform preliminary segmentation of the cell nucleus image, in which the fully connected layer convolution and skip connection are used to improve the accuracy of image segmentation, then improve the GAN, introduce splitting branches into the discriminator structure, and combine the GAN and the splitting network into one. At the same time, pixel loss is introduced in the generator to obtain a nucleus image that is visually more similar to the real image. Finally, the segmented image output by the FCN model is used as the input of the GAN to achieve high-precision segmentation of the nucleus image. The proposed method is experimentally demonstrated based on the 2018 data science bowl data set. The results show that it can achieve rapid convergence, and the mean intersection over union (MIoU) is 85.34%, which is better than other comparison methods.\",\n \"Title: HTIDB: Hierarchical Time-Indexed Database for Efficient Storage and Access to Irregular Time-series Health Sensor Data.\\nYear: 2022\\n\\nAbstract: With the enormous amount of data collected by unobtrusive sensors, the potential of utilizing these data and applying various multi-modal advanced analytics on them is numerous and promising. However, taking advantage of the ever-growing data requires high-performance data-handling systems to enable high data scalability and easy data accessibility. This paper demonstrates robust design, developments, and techniques of a hierarchical time-indexed database for decision support systems leveraging irregular and sporadic time series data from sensor systems, e.g., wearables or environmental. We propose a technique that leverages the flexibility of general purpose, high-scalability database systems, while integrating data analytics focused column stores that leverage hierarchical time indexing, compression, and dense raw numeric data storage. We have evaluated the performance characteristics and tradeoffs of each to understand the data access latencies and storage requirements, which are key elements for capacity planning for scalable systems.\",\n \"Title: Achieving Efficient and Adaptable Dispatching for Vehicle-to-Grid Using Distributed Edge Computing and Attention-Based LSTM\\nYear: 2022\\n\\nAbstract: With the popularity of electric vehicles (EVs), vehicle-to-grid (V2G) technology is attracting increasing attention due to its crucial merit of enabling bidirectional power flows between EVs and grid, so as to enhance the grid security and stability by regulated dispatching. However, the existing V2G approaches are confronted with several unrealizable challenges because of high computational complexity for large-scale EVs and impracticality for future power data acquisition. In this article, an edge computing framework is proposed in a distributed manner to ensure the dispatching efficiently and provide the raw dataset flexibly. Meanwhile, the long short-term memory network is applied to prediction merely by the past and present power data. Moreover, attention mechanism and data clustering are utilized to improve the prediction accuracy and operation robustness. Experiments involving real dataset demonstrated that the proposed V2G scheme is able to achieve very satisfactory dispatching performance with the prediction accuracy up to 98.89%.\",\n \"Title: Real-Time Prediction System of Train Carriage Load Based on Multi-Stream Fuzzy Learning\\nYear: 2022\\n\\nAbstract: When a train leaves a platform, knowing the carriage load (the number of passengers in each carriage) of this train will support train managers to guide passengers at the next platform to choose carriages to avoid congestion. This capacity has become critical since the onset of the pandemic. However, with the dynamicity of passengers and the speed of trains improved (about 3 minutes travel between stations) as well as the station stop period reduced (60–90 second per station), the real-time prediction is more challenging. This paper presents an intelligent system, which is developed in collaboration with Sydney Trains, for real-time predicting carriage load across a city passenger train network. The system comprises three innovations. First, a fuzzy time-matching method significantly improves prediction accuracy in the uncertain situations and allows noisy historical data to be used for training. Second, the LightGBM model is extended with an incremental learning scheme to make forecasting in real-time possible. Third, a new multi-stream learning strategy that merges data streams with similar concept drift patterns is pioneered to increase the amount of suitable training data while reducing generalization errors. A comprehensive suite of practical tests on real-world datasets demonstrates the merit of these solutions.\",\n \"Title: Charging RF-Energy Harvesting Devices in IoT Networks With Imperfect CSI\\nYear: 2022\\n\\nAbstract: This article considers energy delivery by a hybrid access point (HAP) to one or more radio-frequency (RF)-energy harvesting devices. Unlike prior works, it considers imperfect and causal channel state information (CSI) and probabilistic constraints that ensure devices receive their required amount of energy over a given planning horizon. To this end, it outlines two novel contributions. The first is a chance-constrained program, which is then solved using a mixed-integer linear program (MILP) coupled with a sample average approximation (SAA) method. The second is a model predictive control (MPC) solution that utilizes the Gaussian mixture model (GMM) and a so-called \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">backoff</i>\\n that is used to tighten probabilistic constraints. The results show that the performance of the MPC-based solution is within 8% of the optimal solution with a probability of 90.8%.\",\n \"Title: Meta-ADD: A meta-learning based pre-trained model for concept drift active detection\\nYear: 2022\\n\\nAbstract: Concept drift is a phenomenon that commonly happened in data streams and need to be detected, because it means the statistical properties of a target variable, which the model is trying to predict, change over time in an unseen way. Most current detection methods are based on a hypothesis test framework. As a result, in these detection methods, a hypothesis test is need to be set, and more importantly, cannot obtain the type of drift. The setting of a hypothesis test requires an understanding of data streams, and cannot obtain the type of concept drift results in the loss of drift information. Hence, in this paper, to get rid of the setting of hypothesis test, and obtain the type of concept drift, we propose Active Drift Detection based on Meta learning (Meta-ADD), a novel framework that learns to classify concept drift by offline pre-training a model on data stream with known drifts, then online fine-tuning model to improve detection accuracy. Specifically, in the pre-trained phase, we extract meta-features based on the error rates of various concept drift, after which a pre-trained model called meta-detector is developed via a prototypical neural network by representing various concept drift classes as corresponding prototypes. In the detection phase, the meta-detector is fine-tuned to adapt to the real data stream via a simple stream-based active learning. Hence, Meta-ADD does not need a hypothesis test to detect concept drifts and identify their types automatically, which can directly support drift understand. The experiment results verify the effectiveness of Meta-ADD.\",\n \"Title: Evaluating the Applicability of PERSIANN-CDR Products in Drought Monitoring: A Case Study of Long-Term Droughts over Huaihe River Basin, China\\nYear: 2022\\n\\nAbstract: In this study, Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) was evaluated for the assessment of long-term drought monitoring in Huaihe River Basin using daily gauge observation data for the period from 1983 to 2017. The evaluation results show that the PERSIANN-CDR algorithm has a good detection ability for small precipitation events over the whole basin, but a poor ability for extreme precipitation events (>50 mm/day). Daily PERSIANN-CDR estimates perform relatively better in areas with abundant precipitation, while the monthly and yearly PERSIANN-CDR estimates are highly consistent with gauge observations both in magnitude and space. The Standardized Precipitation Index (SPI) at various time scales (3, 6, and 12 months) was calculated based on PERSIANN-CDR and gauge observation, respectively. Grid-based values of statistics derived from those SPI values demonstrate that PERSIANN-CDR has a good ability to capture drought events of each time scale across the basin. However, caution should be applied when using PERSIANN-CDR estimates for basin-scale drought trend analysis. Furthermore, three drought events with long duration and large extent were selected to test the applicability of PERSIANN-CDR in drought monitoring. The results show that it has a good ability to capture when and where droughts occur and how far they spread. Due to the overestimation of small precipitation events, PERSIANN-CDR tends to overestimate the number of extreme droughts and their extents. This needs to be considered in future algorithm improvement.\",\n \"Title: Detecting group concept drift from multiple data streams\\nYear: 2023\\n\\nAbstract: •Proposing a new type of concept drift group concept drift that commonly exists in multiple data streams.•A group concept drift detection method is proposed through detecting the change of error rate.•A new test statistic, free for any distributions with any dimension p, is proposed.•A novel online hypothesis testing based on our proposed test statistic is developed.\",\n \"Title: IA-ICGCN: Integrating Prior Knowledge via Intra-event Association and Inter-event Causality for Chinese Causal Event Extraction\\nYear: 2022\\n\\nAbstract: Causal event extraction (CEE) is a joint extraction task of event detection and event causality discrimination, which is of great value on dialogue system, event prediction and so on. However, the ambiguity of Chinese event description and the implicit causal relationship makes the poor performance with existing models. To deal with this problem, we propose a model to incorporate domain knowledge by taking Intra-event Association and Inter-event Causality into account. We use causal indicators to obtain sentences containing causal relationships from domain texts, and use these sentences to construct event association networks and causality transition networks. To obtain complete event expressions and accurate event causality, we use graph convolutional neural networks (GCN) to encode the information of the two networks separately. Finally, all the information are fed into the Bidirectional Long Short-Term Memory networks. Experimental results on two datasets show that our method outperforms the state-of-the-art baselines.\",\n \"Title: Research on belt foreign body detection method based on deep learning\\nYear: 2022\\n\\nAbstract: Recently, accelerating the improvement in the level of iron ore mining has become extremely important for the sustainable development of the steel industry. Various foreign objects such as steel bars, wood, and plastic pipes easily appear on iron ore belt conveyors, which cause damage to equipment and harm the personal safety of mining workers. Accordingly, a lightweight detection model based on you only look once (YOLO)v3 is proposed in this study. This study first uses the median filter method to preprocess the belt foreign body image to remove the influence of dust and improve the clarity of ore edges. Second, we train the YOLOv3 belt foreign matter detection algorithm based on the selected data set to detect belt foreign matter and evaluate the model based on mean average precision (mAP) and other indicators. Finally, after implementing the sparse training based on the batch normalization (BN) layers, the channel-pruning and layer-pruning strategies are implemented to simplify the YOLOv3 model, followed by parameter fine-tuning. When the accuracy of the model is not affected, our model realizes smaller calculations, faster processing, and a smaller size compared to the original YOLOv3 model. Hence, the model effectively achieves real-time recognition of foreign matter on the ore conveyor belt.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":138,"string":"138"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":68,"string":"68"}}},{"rowIdx":69,"cells":{"question_id":{"kind":"string","value":"Maarten van Steen"},"question":{"kind":"string","value":"Generate an abstract for the title \"Designing highly parallel applications using database programming concepts\" using the following items: 1. Parallel programming models \n2. Cooperative processes\n3. Content-addressable storage structures \n4. Nonnavigational data manipulation \n5. Improved performance"},"answer":{"kind":"string","value":"Current parallel programming models suffer from the serious drawback that they have evolved from models intended to describe collections of concurrent processes competing for common resources and services. The intention of concurrent systems is in conflict with the one of parallel programs, where processes cooperate to achieve a common goal rather than compete. It is therefore required to devise a sufficiently different programming model, that provides adequate abstraction over the problems related to parallel programming.We propose a new parallel programming model which adopts common, content-addressable storage structures. The model advocates nonnavigational manipulation of data, an aspect which has been widely recognized in the database community. We draw a comparison with more conventional models based on shared variables and message passing. As we will show, a model based on common, content-addressable storage provides a substantial improvement over more conventional models."},"correct_answer":{"kind":"string","value":"Current parallel programming models suffer from the serious drawback that they have evolved from models intended to describe collections of concurrent processes competing for common resources and services. The intention of concurrent systems is in conflict with the one of parallel programs, where processes cooperate to achieve a common goal rather than compete. It is therefore required to devise a sufficiently different programming model, that provides adequate abstraction over the problems related to parallel programming.We propose a new parallel programming model which adopts common, content-addressable storage structures. The model advocates nonnavigational manipulation of data, an aspect which has been widely recognized in the database community. We draw a comparison with more conventional models based on shared variables and message passing. As we will show, a model based on common, content-addressable storage provides a substantial improvement over more conventional models."},"documents":{"kind":"list like","value":["Title: Secure peer sampling\nYear: 2010\n\nAbstract: Gossiping has been identified as a useful building block for the development of large-scale, decentralized collaborative systems. With gossiping, individual nodes periodically interact with random partners, exchanging information about their local state; yet, they may globally provide several useful services, such as information diffusion, topology management, monitoring, load-balancing, etc. One fundamental building block for developing gossip protocols is peer sampling, which provides nodes with the ability to sample the entire population of nodes in order to randomly select a gossip partner. In existing implementations, however, one fundamental aspect is neglected: security. Byzantine nodes may subvert the peer sampling service and bias the random selection process, for example, by increasing the probability that a fellow malicious node is selected instead of a random one. The contribution of this paper is an extension to existing peer sampling protocols with a detection mechanism that identifies and blacklists nodes that are suspected of behaving maliciously. An extensive experimental evaluation shows that our extension is efficient in dealing with a large number of malicious nodes.","Title: Group Monitoring in Mobile Ad-Hoc Networks.\nYear: 2009\n\nAbstract: Maintaining bonds of cohesion between members of small groups in densely populated venues (e.g., a family in an amusement park, or some friends in a stadium) is increasingly gaining interest, both as a safety measure against malicious activity and as a convenient tool to prevent group splitting. Note that the use of mobile phones is often ruled out in such scenarios, due to extreme network load. Current solutions are typically based on custom installations of antennas, centralized control, and user devices with high transmission power. In this work we propose a novel method for anonymously spreading presence information among group members in dense environments, based on a completely decentralized mobile ad hoc network approach. Our system operates independently of any infrastructure and is targetted at resource constrained, inexpensive and expendable user devices. Quite importantly, our system protects the privacy of its users, both for their safety and for ethical reasons.","Title: An experimental evaluation of self-managing availability in shared data spaces\nYear: 2007\n\nAbstract: With its decoupling of processes in space and time, the shared data space model has proven to be a well-suited solution for developing distributed component-based systems. However, as in many distributed applications, functional and extra-functional aspects are still interwoven in components. In this paper, we address how shared data spaces can support the separation of concerns. In particular, we present a solution that allows developers to merely specify availability requirements for data tuples, while the underlying middleware evaluates various distribution and replication policies in order to select the one that meets these requirements best. Moreover, in our approach, the middleware continuously monitors the behavior of application and system components, and switches to different policies if this would lead to better results. We describe our approach, along with the design of a prototype implementation and its quantitative evaluation.","Title: A scalable middleware solution for advanced wide-area web services\nYear: 1999\n\nAbstract: To alleviate scalability problems in the Web, many researchers concentrate on how to incorporate advanced caching and replication techniques. Many solutions incorporate object-based techniques. In particular, Web resources are considered as distributed objects offering a well-defined interface. We argue that most proposals ignore two important aspects. First, there is little discussion on what kind of coherence should be provided. Proposing specific caching or replication solutions makes sense only if we know what coherence model they should implement. Second, most proposals treat all Web resources alike. Such a one-size-fits-all approach will never work in a wide-area system. We propose a solution in which Web resources are encapsulated in physically distributed shared objects. Each object should not only encapsulate state and operations, but also the policy by which its state is distributed, cached, replicated, migrated, etc.","Title: Offloading servers with collaborative video on demand\nYear: 2008\n\nAbstract: The peer-to-peer (P2P) paradigm provides a data distribution model that may be attractive for Video on Demand (VoD) as it allows to decrease the costs and to increase the scalability of video distribution. However, VoD is more challenging for P2P technology than file sharing or live streaming, and so, practically feasible VoD systems proposed to date rely on a backend server infrastructure as a fail-over solution. In this paper we investigate how the dependency on servers can be decreased by optimizing the video piece-selection strategy and by allowing multiple peers to form a collaboration for obtaining a single video. In a set of simulations of a trace-based system model we show that for systems such as YouTube the proposed optimizations would result in savings of as much as 70% of the server bandwidth. These simulation results confirm the conclusions of an analytical study of our optimizations, the essential part of which is also included in this paper.","Title: Hybrid dissemination: adding determinism to probabilistic multicasting in large-scale P2P systems\nYear: 2007\n\nAbstract: Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes.","Title: Latency-Driven Replica Placement\nYear: 2005\n\nAbstract: This paper presents HotZone, an algorithm to place replicas in a wide-area network such that the client-to-replica latency is minimized. Similar to the previously proposed HotSpot algorithm, HotZone places replicas on nodes that along with their neighboring nodes generate the highest load. In contrast to HotSpot, however, HotZone provides nearly-optimal results by considering overlapping neighborhoods. HotZone relies on a geometric model of Internet latencies, which effectively reduces the cost of placing K replicas among N potential replica locations from O(N^2) to O(N · max(logN, K)).","Title: Gossiping in distributed systems\nYear: 2007\n\nAbstract: Gossip-based algorithms were first introduced for reliably disseminating data in large-scale distributed systems. However, their simplicity, robustness, and flexibility make them attractive for more than just pure data dissemination alone. In particular, gossiping has been applied to data aggregation, overlay maintenance, and resource allocation. Gossiping applications more or less fit the same framework, with often subtle differences in algorithmic details determining divergent emergent behavior. This divergence is often difficult to understand, as formal models have yet to be developed that can capture the full design space of gossiping solutions. In this paper, we present a brief introduction to the field of gossiping in distributed systems, by providing a simple framework and using that framework to describe solutions for various application domains.","Title: Gossip-based peer sampling\nYear: 2007\n\nAbstract: Gossip-based communication protocols are appealing in large-scale distributed applications such as information dissemination, aggregation, and overlay topology management. This paper factors out a fundamental mechanism at the heart of all these protocols: the peer-sampling service. In short, this service provides every node with peers to gossip with. We promote this service to the level of a first-class abstraction of a large-scale distributed system, similar to a name service being a first-class abstraction of a local-area system. We present a generic framework to implement a peer-sampling service in a decentralized manner by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself. Our framework generalizes existing approaches and makes it easy to discover new ones. We use this framework to empirically explore and compare several implementations of the peer-sampling service. Through extensive simulation experiments we show that---although all protocols provide a good quality uniform random stream of peers to each node locally---traditional theoretical assumptions about the randomness of the unstructured overlays as a whole do not hold in any of the instances. We also show that different design decisions result in severe differences from the point of view of two crucial aspects: load balancing and fault tolerance. Our simulations are validated by means of a wide-area implementation.","Title: Securely Replicated Web Documents\nYear: 2005\n\nAbstract: In order to achieve better scalability and reduce latency in handling user requests, many Web applications make extensive use of data replication through caches and Content Delivery Networks. However, in such scenarios data is often placed on untrusted hosts. As a result, existing replication mechanisms open a wide class vulnerabilities, ranging from denial of service to content masquerading. In this paper we present an architecture that combines data content, replication strategies and security in one unified object model and offers integrity guarantees for Web documents replicated on non secure servers.","Title: Identifying Malicious Peers Before It's Too Late: A Decentralized Secure Peer Sampling Service\nYear: 2007\n\nAbstract: Many unstructured peer to peer (P2P) systems rely on a Peer Sampling Service (PSS) that returns randomly sampled nodes from the population comprising the system. PSS protocols are often implemented using \"gossiping\" approaches in which connected nodes exchange their links in a randomized way. However, such services can be defeated easily by malicious nodes executing \"hub attacks\" which distort the PSS such that all nodes in the network, ultimately, only gain access to malicious nodes. From this leading status - i.e. being a \"hub\" - the malicious nodes can affect the overlay in several ways, ranging from total network disruption to obtaining an application dependent advantage. We present a completely distributed defense against such attacks and give results from simulation experiments. The approach is generic as it is independent of the adopted PSS implementation.","Title: Collaborative filtering using random neighbours in peer-to-peer networks\nYear: 2009\n\nAbstract: Traditionally, collaborative filtering (CF) algorithms used for recommendation operate on complete knowledge. This makes these algorithms hard to employ in a decentralized context where not all users' ratings can be available at all locations. In this paper we investigate how the well-known neighbourhood-based CF algorithm by Herlocker et al. operates on partial knowledge; that is, how many similar users does the algorithm actually need to produce good recommendations for a given user, and how similar must those users be. We show for the popular MovieLens 1,000,000 and Jester datasets that sufficiently good recommendations can be made based on the ratings of a neighbourhood consisting of a relatively small number of randomly selected users.","Title: Enforcing Data Integrity in Very Large Ad Hoc Networks\nYear: 2007\n\nAbstract: Ad hoc networks rely on nodes forwarding each other's packets, making trust and cooperation key issues for ensuring network performance. As long as all nodes in the network belong to the same organization and share the same goal (in military scenarios, for example), it can generally be expected that all nodes can be trusted. However, as wireless technology becomes more commonplace, we can foresee the appearance of very large, heterogeneous networks where the intentions of neighboring nodes are unknown. Without any security measures in place, any node is capable of compromising the integrity of the data it forwards. Our goal in this paper is to ensure the integrity of the data being disseminated without resorting to complex and expensive solutions. We achive this by discouraging malicious behavior in two ways: a) enforcing integrity checks close to the source and b) refusing to communicate with obviously malicious nodes. We find that by having nodes sample their traffic for corrupted messages, malicious nodes can be identified with high accuracy, in effect transforming our collection o f nodes into a self-policing network.","Title: Managing clouds: a case for a fresh look at large unreliable dynamic networks\nYear: 2006\n\nAbstract: Peer-to-peer (P2P) protocols have proven efficient to provide scalable support to many large-scale distributed applications, successfully coping with unreliability and dynamics. However, to exploit them in a wider range of environments, such as very large-scale networks of smartphones or set-top boxes, it is imperative to make P2P protocols manageable: we need to be able to start, bootstrap and stop protocols, and assign resources dynamically. In this paper we present a general-purpose framework aimed to support several fully distributed applications running independently over a very large scale and dynamic pool of resources. We call this resource pool a cloud. The basic idea of the framework is a declarative application suit description, that describes what applications should be running on what resources, and a middleware that makes sure the currently available and dynamic cloud self-organizes into the configuration represented by the description, creating the subclouds that are assigned to applications. The middleware also provides additional functionality, such as bootstrapping overlay networks, to support the applications. Our preliminary ideas on the implementation rely on various gossip-based protocols, that are applied to form the subclouds and to implement bootstrapping, monitoring and control services. Most of all, this position paper sets an exciting research agenda to fully exploit the possibilities offered by very large scale dynamic networks.","Title: PolderCast: fast, robust, and scalable architecture for P2P topic-based pub/sub\nYear: 2012\n\nAbstract: We propose PolderCast, a P2P topic-based Pub/Sub system that is (a) fault-tolerant and robust, (b) scalable w.r.t the number of nodes interested in a topic and number of topics that nodes are interested in, and (c) fast in terms of dissemination latency while (d) attaining a low communication overhead. This combination of properties is provided by an implementation that blends deterministic propagation over maintained rings with probabilistic dissemination following a limited number of random shortcuts. The rings are constructed and maintained using gossiping techniques. The random shortcuts are provided by two distinct peer-sampling services: Cyclon generates purely random links while Vicinity produces interest-induced random links. We analyze PolderCast and survey it in the context of existing approaches. We evaluate PolderCast experimentally using real-world workloads from Twitter and Facebook traces. We use widely renowned Scribe [5] as a baseline in a number of experiments. Robustness with respect to node churn is evaluated through traces from the Skype superpeer network. We show that the experimental results corroborate all of the above properties in settings of up to 10K nodes, 10K topics, and 5K topics per-node.","Title: Scalable analysis for large social networks: the data-aware mean-field approach\nYear: 2012\n\nAbstract: Studies on social networks have proved that endogenous and exogenous factors influence dynamics. Two streams of modeling exist on explaining the dynamics of social networks: 1) models predicting links through network properties, and 2) models considering the effects of social attributes. In this interdisciplinary study we work to overcome a number of computational limitations within these current models. We employ a mean-field model which allows for the construction of a population-specific model informed from empirical research for predicting links from both network and social properties in large social networks.. The model is tested on a population of conference coauthorship behavior, considering a number of parameters from available Web data. We address how large social networks can be modeled preserving both network and social parameters. We prove that the mean-field model, using a data-aware approach, allows us to overcome computational burdens and thus scalability issues in modeling large social networks in terms of both network and social parameters. Additionally, we confirm that large social networks evolve through both network and social-selection decisions; asserting that the dynamics of networks cannot singly be studied from a single perspective but must consider effects of social parameters.","Title: Design Level Support for Parallel and Distributed Applications\nYear: 1996\n\nAbstract: The growing interest in using a cluster of workstations as the target platform for high-performance applications, ha s again emphasized the need for support tools that can be used during application design. In this paper we present a graphical technique, calledADL-D, that allows a devel- oper to construct an application in terms of communicat- ing processes. The technique distinguishes itself from oth - ers by its use of highly orthogonal concepts, and the sup- port for automated code generation. Developers are en- couraged to concentrate on designing components in iso- lation, making the complex design space more manage- able than would otherwise be the case.ADL-D can be used from the early phases of application design through phases that concentrate on algorithmic design, and final imple- mentation on some target platform. Rather than present- ing details of ADL-D, we use it here as a vehicle for a more general discussion on design level support for parallel and distributed applications.","Title: The peer sampling service: experimental evaluation of unstructured gossip-based implementations\nYear: 2004\n\nAbstract: In recent years, the gossip-based communication model in large-scale distributed systems has become a general paradigm with important applications which include information dissemination, aggregation, overlay topology management and synchronization. At the heart of all of these protocols lies a fundamental distributed abstraction: the peer sampling service. In short, the aim of this service is to provide every node with peers to exchange information with. Analytical studies reveal a high reliability and efficiency of gossip-based protocols, under the (often implicit) assumption that the peers to send gossip messages to are selected uniformly at random from the set of all nodes. In practice -- instead of requiring all nodes to know all the peer nodes so that a random sample could be drawn -- a scalable and efficient way to implement the peer sampling service is by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself.This paper presents a generic framework to implement reliable and efficient peer sampling services. The framework generalizes existing approaches and makes it easy to introduce new ones. We use this framework to explore and compare several implementations of our abstraction. Through extensive experimental analysis, we show that all of them lead to different peer sampling services none of which is uniformly random. This clearly renders traditional theoretical approaches invalid, when the underlying peer sampling service is based on a gossip-based scheme. Our observations also help explain important differences between design choices of peer sampling algorithms, and how these impact the reliability of the corresponding service.","Title: A distributed shared data space for personal health systems.\nYear: 2006\n\nAbstract: Ubiquitous computing is a promising paradigm to support health care outside traditional care institutes. Sensor-based systems may continuously collect data on a person's health status and context, and provide immediate feedback or contact a remote physician. This paper presents a novel programming model to facilitate the development of such systems. The model, which has been inspired by tuple spaces, offers robustness for ad hoc mobile environments and explicit support for data streams","Title: On the value of random opinions in decentralized recommendation\nYear: 2006\n\nAbstract: As the amount of information available to users continues to grow, filtering wanted items from unwanted ones becomes a dominant task. To this end, various collaborative-filtering techniques have been developed in which the ratings of items by other users form the basis for recommending items that could be of interest for a specific person. These techniques are based on the assumption that having ratings from similar users improves the quality of recommendation. For decentralized systems, such as peer-to-peer networks, it is generally impossible to get ratings from all users. For this reason, research has focused on finding the best set of peers for recommending items for a specific person. In this paper, we analyze to what extent the selection of such a set influences the quality of recommendation. Our findings are based on an extensive experimental evaluation of the MovieLens data set applied to recommending movies. We find that, in general, a random selection of peers gives surprisingly good recommendations in comparison to very similar peers that must be discovered using expensive search techniques. Our study suggests that simple decentralized recommendation techniques can do sufficiently well in comparison to these expensive solutions.","Title: Tribler: A Social-Based Peer-To-Peer System\nYear: 2008\n\nAbstract: Most current peer-to-peer (P2P) file-sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes or interests may well be exploited in such systems in order to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm's main concepts such as taste buddies and friends, we have designed and implemented the TRIBLER P2P file-sharing system as a set of extensions to BitTorrent. We present and discuss the design of TRIBLER, and we show evidence that TRIBLER enables fast content discovery and recommendation at a low additional overhead, and a significant improvement in download performance. Copyright (c) 2007 John Wiley & Sons, Ltd.","Title: Analysis of Caching and Replication Strategies for Web Applications\nYear: 2007\n\nAbstract: Developers often use replication and caching mechanisms to enhance Web application performance. The authors present a qualitative and quantitative analysis of state-of-the art replication and caching techniques used to host Web applications. Their analysis shows that selecting the best mechanism depends heavily on data workload and requires a careful review of the application's characteristics. They also propose a technique for Web practitioners to compare different mechanisms' performance on their own.","Title: Computer Science, Informatics, and the Networked World\nYear: 2011\n\nAbstract: Many of today's students barely know what a desktop computer is, much less want to focus their studies on the traditional computer science curriculum. Instead, professors should consider a cross-disciplinary approach that crosses fences and helps students learn what's behind the networked world they live in.","Title: The hidden pub/sub of spotify: (industry article)\nYear: 2013\n\nAbstract: Spotify is a peer-assisted music streaming service that has gained worldwide popularity. Apart from providing instant access to over 20 million music tracks, Spotify also enhances its users' music experience by providing various features for social interaction. These are realized by a system using the widely-adopted pub/sub paradigm. In this paper we provide an interesting case study of a hybrid pub/sub system designed for real-time as well as offline notifications for Spotify users. We firstly describe a multitude of use cases where pub/sub is applied. Secondly, we study the design of its pub/sub system used for matching, disseminating and persisting billions of publications every day. Finally, we study pub/sub traffic collected from the production system, derive characterizations of the pub/sub workload, and show some interesting findings and trends.","Title: Sandnet: network traffic analysis of malicious software\nYear: 2011\n\nAbstract: Dynamic analysis of malware is widely used to obtain a better understanding of unknown software. While existing systems mainly focus on host-level activities of malware and limit the analysis period to a few minutes, we concentrate on the network behavior of malware over longer periods. We provide a comprehensive overview of typical malware network behavior by discussing the results that we obtained during the analysis of more than 100,000 malware samples. The resulting network behavior was dissected in our new analysis environment called Sandnet that complements existing systems by focusing on network traffic analysis. Our in-depth analysis of the two protocols that are most popular among malware authors, DNS and HTTP, helps to understand and characterize the usage of these prevalent protocols.","Title: From Remote Objects to Physically Distributed Objects\nYear: 1999\n\nAbstract: Present-day object-oriented middleware provides little support for the distribution, replication and caching of the state of a distributed object. This makes these platforms unsuitable for the development of large-scale distributed applications. We argue that the model of distributed objects on which these middleware platforms are based hinders the addition of comprehensive distribution and replication support to these platforms. We present an alternative view of distributed objects, in which objects are not only in control of the functional aspects of their implementation but also in control of their nonfunctional aspects, in particular, the distribution and replication of their state. We claim that a middleware platform based on this view of distributed objects is better suited for developing the large-scale applications of the future.","Title: Technical challenges in market-driven automated service provisioning\nYear: 2008\n\nAbstract: In today's practice, we see readily precomposed commercial service bundles, such as a spam-free email box, consisting of more elementary services like mail storage and a spam-filter. However, these bundles may be suboptimal from the customer's perspective in terms of price and/or the elementary services that constitute the bundle. It would be advantageous to the customer if a service bundle more closely fulfilled the customer's individual requirements, by selecting the most appropriate elementary services included in the bundle. Also, by obtaining the bundle from a consortium of suppliers, rather than just one single supplier, the elementary services of each supplier with the best cost/benefit ratio can be selected. To put this vision into reality, we need middleware facilitating the automated composition of multisupplier bundles out of basic commercial services available online. We take the stand that the business nature of commercial services imposes leading requirements on the technical design of the middleware. Most importantly, the middleware should be fair in the sense that no single supplier obtains a preferred position in terms of service selection to satisfy a specific customer need. Also, the middleware should be able to deal with alternative services as offered by many competing suppliers, not to speak about the combinatoric explosion, resulting from combining the available services into candidate services bundles. We present a list of problems to be solved to arrive at middleware for multi-supplier service selection, bundling and provisioning. Also, we review existing work, usable to build a fair and efficient middleware solution for commercial service provisioning.","Title: A probabilistic replication and storage scheme for large wireless networks of small devices\nYear: 2008\n\nAbstract: Nodes in wireless ad hoc networks are often limited in terms of resources, such as storage, power, and bandwidth. A downside of this is the fact that local storage at one node cannot accommodate the vast amount of data contained in the network. In this paper, we present SharedState, a scheme for storage, replication, and distribution of common-interest data in wireless networks of resource-constrained devices (e.g. sensor nodes or embedded devices). SharedState works under the assumption that individual nodes would greatly benefit from having access to the wealth of information in the network, but are unable to store it locally at once. SharedState strives to make data available to every node by providing local access to a subset of the whole collection of data items in the network at any moment in time and ensuring that this subset is updated periodically. This is accomplished by probabilistic propagation and replication of data items, ensuring the availability and persistence of information in the face of changing network conditions. We evaluate the performance of SharedState by studying the effectiveness with which nodes can gather information from the network. In addition, we optimize the bandwidth usage of our proposed solution by minimizing unnecessary communication based on feedback from the local neighborhood.","Title: Characterizing Internet performance to support wide-area application development\nYear: 2000\n\nAbstract: To help in our wide-area application development, we have done an informal study of the relation between wide-area latency, the number of routers, and geographical distance between Internet sites. We did this by performing ping and traceroute measurements between 19 sites distributed across the globe. Contrary to our expectation there is almost no correlation between distance, latency, and number of routers in the current Internet. To help further studies of these characteristics the problems of this pilot project are also described.","Title: Simplified Distributed Programming With Micro Objects\nYear: 2010\n\nAbstract: Developing large-scale distributed applications can be a daunting task. Object-based environments have attempted to alleviate problems by providing distributed objects that look like local objects. We advocate that this approach has actually only made matters worse, as the developer needs to be aware of many intricate internal details in order to adequately handle partial failures. The result is an increase of application complexity. We present an alternative in which distribution transparency is lessened in favor of clearer semantics. In particular, we argue that a developer should always be offered the unambiguous semantics of local objects, and that distribution comes from copying those objects to where they are needed. We claim that it is often sufficient to provide only small, immutable objects, along with facilities to group objects into clusters.","Title: On hierarchical routing in wireless sensor networks\nYear: 2009\n\nAbstract: Hierarchical routing is a promising approach for point-to-point routing with very small routing state. While there are many theoretical analyses and high-level simulations demonstrating its benefits, there has been little work to evaluate it in a realistic wireless sensor network setting. Based on numerous proposed hierarchical routing infrastructures, we develop a framework that captures the common characteristics of the infrastructures and identifies design points where the infrastructures differ. We then evaluate the implementation of the framework in TOSSIM and on a 60-node testbed. We demonstrate that from the practical perspective hierarchical routing is also an appealing routing approach for sensor networks. Despite only logarithmic routing state, it can offer low routing stretch: the average of ∼1.25 and the 99-th percentile of 2. Moreover, a hierarchical routing infrastructure can be autonomously bootstrapped and maintained by the nodes. By exploring the design points within our framework, the hierarchy maintenance protocol can optimize different metrics, such as the latency of bootstrapping and repairing the hierarchy after failures or the traffic volume, depending on the application requirements. Finally, we also identify a number of practical issues which we believe the applications employing hierarchical routing should be aware of.","Title: EvAg: a scalable peer-to-peer evolutionary algorithm\nYear: 2010\n\nAbstract: This paper studies the scalability of an Evolutionary Algorithm (EA) whose population is structured by means of a gossiping protocol and where the evolutionary operators act exclusively within the local neighborhoods. This makes the algorithm inherently suited for parallel execution in a peer-to-peer fashion which, in turn, offers great advantages when dealing with computationally expensive problems because distributed execution implies massive scalability. In this paper we show another advantage of this algorithm: We experimentally demonstrate that it scales up better than traditional alternatives even when executed in a sequential fashion. In particular, we analyze the behavior of several EAs on well-known deceptive trap functions with varying sizes and levels of deceptiveness. The results show that the new EA requires smaller optimal population sizes and fewer fitness evaluations to reach solutions. The relative advantage of the new EA is more outstanding as problem hardness and size increase. In some cases the new algorithm reduces the computational efforts of the traditional EAs by several orders of magnitude.","Title: GlobeDB: autonomic data replication for web applications\nYear: 2005\n\nAbstract: We present GlobeDB, a system for hosting Web applications that performs autonomic replication of application data. GlobeDB offers data-intensive Web applications the benefits of low access latencies and reduced update traffic. The major distinction in our system compared to existing edge computing infrastructures is that the process of distribution and replication of application data is handled by the system automatically with very little manual administration. We show that significant performance gains can be obtained this way. Performance evaluations with the TPC-W benchmark over an emulated wide-area network show that GlobeDB reduces latencies by a factor of 4 compared to non-replicated systems and reduces update traffic by a factor of 6 compared to fully replicated systems.","Title: Gossip-Based Self-Management of a Recursive Area Hierarchy for Large Wireless SensorNets\nYear: 2010\n\nAbstract: A recursive multihop area hierarchy has a number of applications in wireless sensor networks, the most common being scalable point-to-point routing, so-called hierarchical routing. In this paper, we consider the problem of maintaining a recursive multihop area hierarchy in large sensor networks. We present a gossip-based protocol, dubbed PL-Gossip, in which nodes, by using local-only operations and by periodically gossiping with their neighbors, collaboratively maintain such a hierarchy. Since the hierarchy is a complex distributed structure, PL-Gossip introduces special mechanisms for internode coordination and consistency enforcement. Yet, these mechanisms are seamlessly integrated within the basic gossiping framework. Through simulations and experiments with an actual embedded protocol implementation, we demonstrate that PL-Gossip maintains the hierarchy in a manner that addresses all the peculiarities of sensor networks. More specifically, it offers excellent opportunities for aggressive energy saving and facilitates provisioning energy harvesting infrastructure. In addition, it bootstraps and recovers the hierarchy after failures relatively fast while also being robust to message loss. Finally, it can seamlessly operate on real sensor node hardware in realistic deployment scenarios and can outperform existing state-of-the-art hierarchy maintenance protocols.","Title: Sub-2-Sub: Self-Organizing Content-Based Publish Subscribe for Dynamic Large Scale Collaborative Networks\nYear: 2006\n\nAbstract: In this paper, we address the problem of constructing scalable content-based publish/subscribe systems. Publish/subscribe sys- tems are asynchronous event-notification systems in which a pub- lished event is forwarded to exactly those nodes that have previously subscribed for that event. Subscriptions can range from a simple specification of merely the type of an event to a specification of the value ranges that an event's attributes can have. Notably the latter poses potential scalability problems. Structured peer-to-peer systems can provide scalable solutions to publish/subscribe systems with simple subscription patterns. For complex subscription types their applicability is less obvious. In this paper, we present SUB-2-SUB, a collaborative self-organizing pub- lish/subscribe system deploying an unstructured overlay network. SUB-2-SUB relies on an epidemic-based algorithm in which peers continuously exchange subscription information to get clustered to similar peers. In contrast to many existing approaches, SUB-2-SUB supports both value-based and interval-based subscriptions. Simu- lations of SUB-2-SUB on synthetic and reusable workloads convey its good properties in terms of routing efficiency, fairness, accuracy and efficiency. dation. space of the latter to the identifier space of the former. At one extreme, each attribute is associated with one specific peer. Although this provides efficient routing to interested subscribers, peers hosting popular attributes are quickly over- loaded. At the other end of the spectrum, in an attempt to discretize the ranges of attributes, a peer is made responsible for a specific (attribute, value) pair. In this case, attaining a scalable implementation for range subscriptions becomes problematic.","Title: Prestige-based peer sampling service: interdisciplinary approach to secure gossip\nYear: 2009\n\nAbstract: The Peer Sampling Service (PSS) has been proposed as a method to initiate and maintain the set of connections between nodes in unstructured peer to peer (P2P) networks. The PSS usually relies on gossip-style communication where participants exchange their links in a randomized way. However, the PSS network organization can be easily modified by malicious nodes running a \"hub attack\", in which they achieve a leading structural position. From this prestigious status, the malicious nodes can severely affect the overlay and achieve several application dependent advantages. We present a novel method to overcome this attack and provide results from simulation experiments that validate our claim. This method is inspired by a simple technique used to detect social leaders in firm's organizations that is based on the social (structural) \"prestige\" of actors.","Title: Optimizing Peer Relationships in a Super-Peer Network\nYear: 2007\n\nAbstract: Super-peer architectures exploit the heterogeneity of nodes in a P2P network by assigning additional responsi- bilities to higher-capacity nodes. In the design of a super- peer network for file sharing, several issues have to be ad- dressed: how client peers are related to super-peers, how super-peers locate files, how the load is balanced among the super-peers, and how the system deals with node failures. In this paper we introduce a self-organizing super-peer net- work architecture (SOSPNET) that solves these issues in a fully decentralized manner. SOSPNET maintains a super- peer network topology that reflects the semantic similarity of peers sharing content interests. Super-peers maintain se- mantic caches of pointers to files which are requested by peers with similar interests. Client peers, on the other hand, dynamically select super-peers offering the best search per- formance. We show how this simple approach can be em- ployed not only to optimize searching, but also to solve gen- erally difficult problems encountered in P2P architectures such as load balancing and fault tolerance. We evaluate SOSPNET using a model of the semantic structure derived from the 8-month traces of two large file-sharing communi- ties. The obtained results indicate that SOSPNET achieves close-to-optimal file search performance, quickly adjusts to changes in the environment (node joins and leaves), sur- vives even catastrophic node failures, and efficiently dis- tributes the system load taking into account peer capacities.","Title: Wikipedia workload analysis for decentralized hosting\nYear: 2009\n\nAbstract: We study an access trace containing a sample of Wikipedia's traffic over a 107-day period aiming to identify appropriate replication and distribution strategies in a fully decentralized hosting environment. We perform a global analysis of the whole trace, and a detailed analysis of the requests directed to the English edition of Wikipedia. In our study, we classify client requests and examine aspects such as the number of read and save operations, significant load variations and requests for nonexisting pages. We also review proposed decentralized wiki architectures and discuss how they would handle Wikipedia's workload. We conclude that decentralized architectures must focus on applying techniques to efficiently handle read operations while maintaining consistency and dealing with typical issues on decentralized systems such as churn, unbalanced loads and malicious participating nodes.","Title: Distributed redirection for the World-Wide Web\nYear: 2005\n\nAbstract: Replication in the World-Wide Web covers a wide range of techniques. Often, the redirection of a client browser towards a given replica of a Web page is performed after the client's request has reached the Web server storing the requested page. As an alternative, we propose to perform the redirection as close to the client as possible in a fully distributed and transparent manner. Distributed redirection ensures that we find a replica wherever it is stored and that the closest possible replica is always found first. By exploiting locality, we can keep latency low.","Title: A Structured Design Technique for Distributed Programs\nYear: 1998\n\nAbstract: A non-formal motivation and description is given ofADL- d, a graphical design technique for parallel and distributed software. ADL-d allows a developer to construct an appli- cation in terms of communicating processes. The technique distinguishes itself from others by its rigid orthogonal ap- proach to communication modeling, which is advantageous in many areas. Without being committed to one particular design method, ADL-d as a technique can be used from the early phases of application design through phases that con- centrate on algorithmic design, and final implementation on some target platform. In this paper, we discuss and motivate all ADL-d components, including recently incorporated fea- tures such as support for connection-oriented communica- tion, and support for modeling dynamically changing com- munication structures.","Title: Group formation among peer-to-peer agents: learning group characteristics\nYear: 2003\n\nAbstract: This paper examines the decentralized formation of groups within a peer-to-peer multi-agent system. More specifically, it frames group formation as a clustering problem, and examines how to determine cluster characteristics such as area and density in the absence of information about the entire data set, such as the number of points, the number of clusters, or the maximum distance between points, that are available to centralized clustering algorithms. We develop a method in which agents individually search for other agents with similar characteristics in a peer-to-peer manner. These agents group into small centrally controlled clusters which learn cluster parameters by examining and improving their internal composition over time. We show through simulation that this method allows us to find clusters of a wide variety of sizes without adjusting agent parameters.","Title: Exploring extreme wireless distributed systems\nYear: 2011\n\nAbstract: Modern distributed systems are increasingly relying on components that need to make use of wireless technology. Examples include subsystems implemented as wireless sensor networks or subsystems making use of mobile computing platforms. In this tutorial, we'll be looking closer into wireless-only distributed systems that are extreme in one or several of the following dimensions: their size in terms of the number of nodes, the resource limitations of those nodes (memory, compute power, energy budget), or the harshness of their environment (lossy channels, mobility). In particular, we'll be discussing issues related to turning such extreme distributed systems into robust ones, addressing questions like: how to set up and maintaining routing paths, how to reliably disseminate information, and how to realize very large ultra-low duty-cycled networks. In the meantime, we draw examples from systems that are aimed at directly supporting human beings.","Title: Gossip-based clock synchronization for large decentralized systems\nYear: 2006\n\nAbstract: Numerous large-scale decentralized systems assume loosely synchronized clocks. Existing time protocols have not been designed for deployment in such systems, since they are complex and require manual configuration. We present the Gossiping Time Protocol (GTP), a completely self-managing epidemic time synchronization algorithm for peer-to-peer networks. In GTP, each node synchronizes its time by gossiping with other nodes. The decisions regarding sample evaluation and gossiping frequency are purely local, yet they result in consistent behavior of the whole system. Large-scale experimental evaluation of a 64,500-node network emulated on 65 machines indicates high scalability and reasonable accuracy of GTP.","Title: Replicating Web Applications On-Demand\nYear: 2004\n\nAbstract: Many Web-based commercial services deliver their content using Web applications that generate pages dynamically based on user profiles, request parameters etc. The workload of these applications are often characterized by a large number of unique requests and a significant fraction of data updates. Hosting these applications drives the need for systems that replicates both the application code and its underlying data. We propose the design of such a system that is based on on-demand replication, where data units are replicated only to servers that access them often. This reduces the consistency overhead as updates are sent to a reduced number of servers. The proposed system allows complete replication transparency to the application, thereby allowing developers to build applications unaware of the underlying data replication. We show that the proposed techniques can reduce the client response time by a factor of 5 in comparison to existing techniques for a real-world e-commerce application used in the TPC-W benchmark. Furthermore, we evaluate our strategies for a wide range of workloads and show that on-demand replication performs better than centralized and fully replicated systems by reducing the average latency of read/write data accesses as well as the amount of bandwidth utilized to maintain data consistency.","Title: Epidemic-Style management of semantic overlays for content-based searching\nYear: 2005\n\nAbstract: A lot of recent research on content-based P2P searching for file- sharing applications has focused on exploiting semantic relations between peers to facilitate searching. To the best of our knowledge, all methods proposed to date suggest reactive ways to seize peers' semantic relations. That is, they rely on the usage of the underlying search mechanism, and infer semantic relations based on the queries placed and the corresponding replies received. In this paper we follow a different approach, proposing a proactive method to build a semantic overlay. Our method is based on an epidemic protocol that clusters peers with similar content. It is worth noting that this peer clustering is done in a completely implicit way, that is, without requiring the user to specify his preferences or to characterize the content of files he shares.","Title: Replication for web hosting systems\nYear: 2004\n\nAbstract: Replication is a well-known technique to improve the accessibility of Web sites. It generally offers reduced client latencies and increases a site's availability. However, applying replication techniques is not trivial, and various Content Delivery Networks (CDNs) have been created to facilitate replication for digital content providers. The success of these CDNs has triggered further research efforts into developing advanced Web replica hosting systems. These are systems that host the documents of a website and manage replication automatically. To identify the key issues in designing a wide-area replica hosting system, we present an architectural framework. The framework assists in characterizing different systems in a systematic manner. We categorize different research efforts and review their relative merits and demerits. As an important side-effect, this review and characterization shows that there a number of interesting research questions that have not received much attention yet, but which deserve exploration by the research community.","Title: Practical large-scale latency estimation\nYear: 2008\n\nAbstract: We present the implementation of a large-scale latency estimation system based on GNP and incorporated into the Google content delivery network. Our implementation employs standard features of contemporary Web clients, and carefully controls the overhead incurred by latency measurements using a scalable centralized scheduler. It also requires only a small number of CDN modifications, which makes it attractive for any CDN interested in large-scale latency estimation. We investigate the issue of coordinate stability over time and show that coordinates drift away from their initial values with time, so that 25% of node coordinates become inaccurate by more than 33ms after one week. However, daily re-computations make 75% of the coordinates stay within 6ms of their initial values. Furthermore, we demonstrate that using coordinates to decide on client-to-replica re-direction leads to selecting replicas closest in term of measured latency in 86% of all cases. In another 10% of all cases, clients are re-directed to replicas offering latencies that are at most two times longer than optimal. Finally, collecting a huge volume of latency data and using clustering techniques enable us to estimate latencies between globally distributed Internet hosts that have not participated in our measurements at all. The results are sufficiently promising that Google may offer a public interface to the latency estimates in the future.","Title: A Security Architecture for Object-Based Distributed Systems\nYear: 2002\n\nAbstract: Large-scale distributed systems present numerous securityproblems not present in local systems. In this paperwe present a general security architecture for a large-scaleobject-based distributed system. Its main features includeways for servers to authenticate clients, clients to authenticateservers, new secure servers to be instantiated withoutmanual intervention, and ways to restrict which client canperform which operation on which object. All of these featuresare done in a platform- and application-independentway, so the results are quite general. The basic idea behindthe scheme is to have each object owner issue cryptographicallysealed certificates to users to prove which operationsthey may request and to servers to prove which operationsthey are authorized to execute. These certificates are usedto ensure secure binding and secure method invocation. Thepaper discusses the required certificates and security protocolsfor using them.","Title: Service-oriented data denormalization for scalable web applications\nYear: 2008\n\nAbstract: Many techniques have been proposed to scale web applications. However, the data interdependencies between the database queries and transactions issued by the applications limit their efficiency. We claim that major scalability improvements can be gained by restructuring the web application data into multiple independent data services with exclusive access to their private data store. While this restructuring does not provide performance gains by itself, the implied simplification of each database workload allows a much more efficient use of classical techniques. We illustrate the data denormalization process on three benchmark applications: TPC-W, RUBiS and RUBBoS. We deploy the resulting service-oriented implementation of TPC-W across an 85-node cluster and show that restructuring its data can provide at least an order of magnitude improvement in the maximum sustainable throughput compared to master-slave database replication, while preserving strong consistency and transactional properties.","Title: A Modeling Framework for Gossip-based Information Spread\nYear: 2011\n\nAbstract: We present an analytical framework for gossip protocols based on the pair wise information exchange between interacting nodes. This framework allows for studying the impact of protocol parameters on the performance of the protocol. Previously, gossip-based information dissemination protocols have been analyzed under the assumption of perfect, lossless communication channels. We extend our framework for the analysis of networks with lossy channels. We show how the presence of message loss, coupled with specific topology configurations, impacts the expected behavior of the protocol. We validate the obtained models against simulations for two protocols.","Title: Transparent Distributed Redirection of HTTP Requests\nYear: 2003\n\nAbstract: Replication in the World-Wide Web covers a wide rangeof techniques. Often, the redirection of a client browser towardsa given replica of a Web page has to be explicit andis performed after the client's request has reached the Webserver storing the requested page. As an alternative, wepropose to perform the redirection as close to the client aspossible in a fully distributed manner. Distributed redirectionensures that we find a replica wherever it is stored andthat the closest possible replica is always found first. Byexploiting locality, we can keep latency low.","Title: A Distributed-Object Infrastructure for Corporate Websites\nYear: 2000\n\nAbstract: A corporate website is the virtual representation of a corporation or organization on the Internet. Corporate websites face numerous problems due to their large size and complexity, and the non-scalability of the underlying Web infrastructure. Current solutions to these problems generally rely on traditional scaling techniques such as caching and replication. These are usually too restrictive, however, taking a one-size-fits-all approach and applying the same solution to every document. We propose Globe as a foundation upon which to build scalable corporate websites, and introduce GlobeDoc, a website model based on Globe distributed shared objects. This paper describes GlobeDoc, highlighting the design and technical details of the infrastructure.","Title: Exploring Design Tradeoffs Of A Distributed Algorithm For Cosmic Ray Event Detection\nYear: 2012\n\nAbstract: Many sensor networks, including large particle detector arrays measuring high-energy cosmic-ray air showers, traditionally rely on centralised trigger algorithms to find spatial and temporal coincidences of individual nodes. Such schemes suffer from scalability problems, especially if the nodes communicate wirelessly or have bandwidth limitations. However, nodes which instead communicate with each other can, in principle, use a distributed algorithm to find coincident events themselves without communication with a central node. We present such an algorithm and consider various design tradeoffs involved, in the context of a potential trigger for the Auger Engineering Radio Array (AERA).","Title: An architecture for a wide area distributed system\nYear: 1996\n\nAbstract: Distributed systems provide sharing of resources and information over a computer network. A key design issue that makes these systems attractive is that all aspects related to distribution are transparent to users. Unfortunately, general-purpose wide area distributed systems that allow users to share and manage arbitrary resources in a transparent way hardly exist. In particular, they generally do not take into account the most important properties that characterize wide area systems: 1) A very large number of users and resources, 2) an inherent latency problem caused by the distance between nodes, 3) heterogeneity due to a variety of underlying operating systems and networks, and 4) involvement of multiple administrative organizations.The research described in this paper is part of the Globe Project (Globe stands for GLobal Object Based Environment). The goal of this project is the design and implementation of a wide area distributed system that provides a convenient programming abstraction and full transparency. The main contribution of this paper is the description of a new system for distributed shared objects. In contrast to other systems, the implementation of distribution, consistency, and replication of state is completely encapsulated in a distributed shared object. This allows for object-specific solutions, and provides the right mechanism for building efficient and truly scalable systems.","Title: Autonomic Data Placement Strategies for Update-intensiveWeb applications\nYear: 2005\n\nAbstract: Edge computing infrastructures have become the leading platform for hosting Web applications. One of the key challenges in these infrastructures is the replication of application data. In our earlier research, we presented GlobeDB, a middleware for edge computing infrastructures that performs autonomic replication of application data. In this paper, we study the problem of data unit placement for updateintensive Web applications in the context of GlobeDB. Our hypothesis is that there exists a continuous spectrum of placement choices between complete partitioning of sets of data units across edge servers and full replication of data units to all servers. We propose and evaluate different families of heuristics for this problem of replica placement. As we show in our experiments, a heuristic that takes into account both the individual characteristics of data units and the overall system load performs best.","Title: Versatile anycasting with mobile IPv6.\nYear: 2006\n\nAbstract: Anycasting was introduced to facilitate efficient communication between distributed Internet services and their clients, as it allows client requests to be automatically routed to nearby service instances. However, even though several any-cast implementations have been proposed, their various limitations prevent them from being widely adopted by large-scale distributed systems.This paper identifies the key limitations of existing anycast implementations, and proposes how to implement anycast such that all these limitations are addressed without harming the performance of anycast communication. Our solution relies on address-translation capabilities present in modern operating systems. These capabilities have originally been designed for communication with mobile nodes. However, we demonstrate that one can exploit them to implement versatile anycasting at low cost.","Title: Prudent Practices for Designing Malware Experiments: Status Quo and Outlook\nYear: 2012\n\nAbstract: Malware researchers rely on the observation of malicious code in execution to collect datasets for a wide array of experiments, including generation of detection models, study of longitudinal behavior, and validation of prior research. For such research to reflect prudent science, the work needs to address a number of concerns relating to the correct and representative use of the datasets, presentation of methodology in a fashion sufficiently transparent to enable reproducibility, and due consideration of the need not to harm others. In this paper we study the methodological rigor and prudence in 36 academic publications from 2006 -- 2011 that rely on malware execution. 40% of these papers appeared in the 6 highest-ranked academic security conferences. We find frequent shortcomings, including problematic assumptions regarding the use of execution-driven datasets (25% of the papers), absence of description of security precautions taken during experiments (71% of the articles), and oftentimes insufficient description of the experimental setup. Deficiencies occur in top-tier venues and elsewhere alike, highlighting a need for the community to improve its handling of malware datasets. In the hope of aiding authors, reviewers, and readers, we frame guidelines regarding transparency, realism, correctness, and safety for collecting and using malware datasets.","Title: A robust and scalable peer-to-peer gossiping protocol\nYear: 2003\n\nAbstract: The newscast model is a general approach for communication in large agent-based distributed systems. The two basic services—membership management and information dissemination—are implemented by the same epidemic-style protocol. In this paper we present the newscast model and report on experiments using a Java implementation. The experiments involve communication in a large, wide-area cluster computer. By analysis of the outcome of the experiments we demonstrate that the system indeed shows the scalability and dependability properties predicted by our previous theoretical and simulation results.","Title: The distributed ASCI Supercomputer project\nYear: 2000\n\nAbstract: The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project.","Title: Optimal Decentralized Formation of k-Member Partnerships\nYear: 2010\n\nAbstract: To keep pace with constantly changing markets, many companies are seeking strategic partnerships. In this paper, we assume that a company can electronically provide a profile of the product or service it has to offer. This profile is described in such a way that potential partners can assess the fitness of the company for eventually teaming up. We concentrate on the fully decentralized optimal formation of teams consisting of k members. This problem boils down to developing a decentralized, efficient algorithm for solving a variant of the maximal weighted k-sub graph problem. We provide a first solution, along with an assessment of its performance, thereby concentrating on the feasibility of an actual embedding in real-world scenarios consisting of thousands of companies. In particular, any solution should be highly adaptive when new or fresh information concerning potential partners comes available.","Title: On Botnets That Use DNS for Command and Control\nYear: 2011\n\nAbstract: We discovered and reverse engineered Feederbot, a botnet that uses DNS as carrier for its command and control. Using k-Means clustering and a Euclidean Distance based classifier, we correctly classified more than 14m DNS transactions of 42,143 malware samples concerning DNS-C&C usage, revealing another bot family with DNS C&C. In addition, we correctly detected DNS C&C in mixed office workstation network traffic.","Title: Dynamically Selecting Optimal Distribution Strategies for Web Documents\nYear: 2002\n\nAbstract: To improve the scalability of the Web, it is common practice to apply caching and replication techniques. Numerous strategies for placing and maintaining multiple copies of Web documents at several sites have been proposed. These approaches essentially apply a global strategy by which a single family of protocols is used to choose replication sites and keep copies mutually consistent. We propose a more flexible approach by allowing each distributed document to have its own associated strategy. We propose a method for assigning an optimal strategy to each document separately and prove that it generates a family of optimal results. Using trace-based simulations, we show that optimal assignments clearly outperform any global strategy. We have designed an architecture for supporting documents that can dynamically select their optimal strategy and evaluate its feasibility.","Title: Unifying User-to-User Messaging Systems\nYear: 2004\n\nAbstract: Unification of user-to-user messaging systems facilitates message exchange independent of time, place, protocol, and end-user device.This article describes an approach to unification that is based on introducing a middleware layer instead of employing gateways. It entails a single system that provides common services such as email, fax, and short messaging, but that can also enable novel services that current messaging systems can't support.The authors also describe how the model can be efficiently implemented on a global scale.","Title: Globule: A Platform for Self-Replicating Web Documents\nYear: 2001\n\nAbstract: Replicating Web documents at a worldwide scale can help reduce user-perceived latency and wide-area network traffic. This paper presents the design of Globule, a platform that automates all aspects of such replication: server-to-server peering negotiation, creation and destruction of replicas, selection of the most appropriate replication strategies on a per-document basis, consistency management and transparent redirection of clients to replicas. Globule is initially directed to support standard Web documents. However, it can also be applied to stream-oriented documents. To facilitate the transition from a non-replicated server to a replicated one, we designed Globule as a module for the Apache Web server. Therefore, converting Web documents should require no more than compiling a new module into Apache and editing a configuration file.","Title: Globe: A Wide-Area Distributed System\nYear: 1999\n\nAbstract: Developing large-scale wide-area applications requires an infrastructure that is presently lacking. Currently, most Internet applications have to be built on top of raw communication services, such as TCP connections. All additional services, including those for naming, replication, migration, persistence, fault tolerance, and security, have to be implemented for each application anew. Not only is this a waste of effort, it also makes interoperability between different applications difficult or even impossible. The authors present a novel, object-based framework for developing wide-area distributed applications. The framework is based on the concept of a distributed shared object, which has the characteristic feature that its state can be physically distributed across multiple machines at the same time. All implementation aspects, including communication protocols, replication strategies, and distribution and migration of state, are part of each object and are hidden behind its interface. The current performance problems of the World-Wide Web are taken as an example to illustrate the benefit of encapsulating state, operations, and implementation strategies on a per-object basis. The authors describe how distributed objects can be used to implement worldwide scalable Web documents.","Title: GSpace: an architectural approach for self-managing extra-functional concerns\nYear: 2008\n\nAbstract: Middleware-based solutions for self-managing systems provide a degree of separation between the mechanisms that govern the adaptability of a system and application functionality. Systems become in this way more flexible, dependable and robust to changes. However, it is possible to achieve another degree of separation by separating from the application logic the different extra-functional concerns (such as availability, performance, and security). This separation, known as Separation of Concerns principle, helps in generating software artifacts that are more maintainable and reusable. In this paper, we propose an architectural model for a middleware-based solution where the self-managing principle is applied to extra-functional concerns. Our middleware, based on the Shared Data Space model, is capable of dynamically adapt extra-functional concerns to the actual needs of the applications.","Title: A method for decentralized clustering in large multi-agent systems\nYear: 2003\n\nAbstract: This paper examines a method of clustering within a fully decentralized multi-agent system. Our goal is to group agents with similar objectives or data, as is done in traditional clustering. However, we add the additional constraint that agents must remain in place on a network, instead of first being collected into a centralized database. To do this we connect agents in a random network and have them search in a peer-to-peer fashion for other similar agents. We thus aim to tackle the basic clustering problem on an Internet scale and create a method by which agents themselves can be grouped, forming coalitions. In order to investigate the feasibility of a decentralized approach, this paper presents a number of simulation experiments involving agents representing two-dimensional points. A comparison between our method's clustering ability and that of the k-means clustering algorithm is presented. Generated data sets containing 2,500 to 160,000 points (agents) grouped in 25 to 1,600 clusters are examined. Results show that our decentralized agent method produces a better clustering than the centralized k-means algorithm, quickly placing 95% to 99% of points correctly. The the time required to find a clustering depends on the quality of solution required; a fairly good solution is quickly converged on, and then slowly improved. Overall, our experiments indicate that the time to find a particular quality of solution increases less than linearly with the number of agents.","Title: Mechanisms for effective caching in the Globe location service\nYear: 2000\n\nAbstract: Globe is a wide-area distributed system that supports mobile objects. To track and locate objects, we use a worldwide distributed location service, implemented as a search tree.An object registers its current position by storing its address in a nearby leaf node of the tree. This knowledge propagates up to the top of the tree, so every object can be found from the root. Remote objects can cache the location of an object. However, if the object moves, the cache entry is no longer valid.In this paper, we show how caching can be made to work effectively even in the presence of mobile objects.","Title: Achieving Scalability in Hierarchical Location Services\nYear: 2002\n\nAbstract: Services for locating mobile objects are often organized as a distributed search tree. The advantage of this approach is that the service can scale as a system grows in size and number of objects. However, a potential problem is that high-level nodes may become a bottleneck affecting the scalability of the service. A traditional solution is to also distribute the location information managed by a single node across multiple machines. We introduce a method that radically applies distribution of location information such that the load is evenly balanced across all machines that form part of the implementation of the service, while at the same time exploiting locality.","Title: Providing data confidentiality against malicious hosts in Shared Data Spaces\nYear: 2010\n\nAbstract: Coordination languages are often used to describe open-ended systems. This makes it challenging to develop tools for guaranteeing the security of the coordinated systems and the correctness of their interaction. Successful approaches to this problem ...","Title: On leveraging social relationships for decentralized privacy-preserving group communication\nYear: 2012\n\nAbstract: Millions of people use the Internet today for data exchange of sensitive information. A typical exchange usually occurs within the context of a group of users and often takes place in a centrally managed infrastructure such as Facebook. Evidence has shown that such systems are unable to properly protect the privacy of its users. Following this observation, we present a framework to support privacy-preserving group communication. Our framework is completely decentralized and leverages the social relationships between users to bootstrap a communication overlay whose robustness is improved with the addition of extra privacy-preserving links. The framework supports multiple groups in a scalable manner and defines mechanisms to handle churn in group membership. Finally, we also outline high-level protocols for a privacy-preserving micro-news application.","Title: A Multiphased Approach for Modeling and Analysis of the BitTorrent Protocol\nYear: 2007\n\nAbstract: BitTorrent is one of the most popular protocols for content distribution and accounts for more than 15% of the total Internet traffic. In this paper, we present an analytical model of the protocol. Our work differs from previous works as it models the BitTorrent protocol specifically and not as a general file-swarming protocol. In our study, we observe that to accurately model the download process of a BitTorrent client, we need to split this process into three phases. We validate our model using simulations and realworld traces. Using this model, we study the efficiency of the protocol based on various protocol-specific parameters such as the maximum number of connections and the peer set size. Furthermore, we study the relationship between changes in the system parameters and the stability of the protocol. Our model suggests that the stability of BitTorrent protocol depends heavily on the number of pieces a file is divided into and the arrival rate of clients to the network.","Title: An Amortized Tit-For-Tat Protocol for Exchanging Bandwidth instead of Content in P2P Networks\nYear: 2007\n\nAbstract: Incentives for resource sharing are crucial for the proper operation of P2P networks. The principle of the incen- tive mechanisms in current content sharing P2P networks such as BitTorrent is to have peers exchange content of mu- tual interest. As a consequence, a peer can actively par- ticipate in the system only if it shares content that is of immediate interest to other peers. In this paper we pro- pose to lift this restriction by using bandwidth rather than content as the resource upon which incentives are based. Bandwidth, in contrast to content, is independent of peer interests and so can be exchanged between any two peers. We present the design of a protocol called amortized tit- for-tat (ATFT) based on the bandwidth-exchange concept. This protocol defines mechanisms for bandwidth exchange corresponding to those in BitTorrent for content exchange, in particular for finding bandwidth borrowers that amortize the bandwidth borrowed in the past with their currently idle bandwidth. In addition to the formally proven incentives for bandwidth contributions, ATFT provides natural solu- tions to the problems of peer bootstrapping, seeding incen- tive, peer link asymmetry, and anonymity, which have previ- ously been addressed with much more complex designs. Ex- periments with a real-world dataset confirm that ATFT is efficient in enforcing bandwidth contributions and results in download performance better than provided by incentive mechanisms based on content exchange.","Title: 2Fast: Collaborative Downloads in P2P Networks\nYear: 2006\n\nAbstract: P2P systems that rely on the voluntary contribution of bandwidth by the individual peers may suffer from freeriding. To address this problem, mechanisms enforcing fairness in bandwidth sharing have been designed, usually by limiting the download bandwidth to the available upload bandwidth. As in real environments the latter is much smaller than the former, these mechanisms severely affect the download performance of most peers. In this paper we propose a system called 2Fast, which solves this problem while preserving the fairness of bandwidth sharing. In 2Fast, we form groups of peers that collaborate in downloading a file on behalf of a single group member, which can thus use its full download bandwidth. A peer in our system can use its currently idle bandwidth to help other peers in their ongoing downloads, and get in return help during its own downloads. We assess the performance of 2Fast analytically and experimentally, the latter in both real and simulated environments. We find that in realistic bandwidth limit settings, 2Fast improves the download speed by up to a factor of 3.5 in comparison to state-of-the-art P2P download protocols.","Title: Dynamically adapting tuple replication for managing availability in a shared data space\nYear: 2005\n\nAbstract: With its decoupling of processes in space and time, the shared data space model has proven to be a well-suited solution for developing distributed component-based systems. However, as in many distributed applications, functional and extra-functional aspects are still interwoven in components. In this paper, we address how shared data spaces can support separation of concerns. In particular, we present a solution that allows developers to merely specify performance and availability requirements for data tuples, while the underlying middleware evaluates various distribution and replication policies in order to select the one that meets these requirements best. Moreover, in our approach, the middleware continuously monitors the behavior of application and system components, and switches to different policies if this would lead to better results. We describe our approach, along with the design of a prototype implementation and its quantitative evaluation.","Title: Scalable strong consistency for web applications\nYear: 2004\n\nAbstract: Web application workloads are often characterized by a large number of unique read requests and a significant fraction of write requests. Hosting these applications drives the need for the next generation CDN architecture that does more than caching the results of Web applications but replicates both the application code and its underlying data. We propose the design of a system that guarantees strong consistency for Web applications with high scalability. The proposed system is based on partial replication, where data units are replicated only to servers that access them often. This reduces the consistency overhead as updates are sent to a reduced number of servers. The novelty of our system is that the proposed partial replication is performed by the system automatically by analyzing the system's access patterns periodically. We explore the design space of this system, find the key issues that need to be addressed to build it and propose solutions to solve them. We further show that the proposed algorithms offer significant performance gains compared to existing solutions for a wide range of Web access patterns.","Title: Broker-placement in latency-aware peer-to-peer networks\nYear: 2008\n\nAbstract: In large peer-to-peer (P2P) overlay networks, nodes usually share resources to support all kinds of applications. In such networks, a subset of the nodes may assume the role of broker in order to act as intermediaries for finding the shared resources. When some notion of distance between nodes such as the internode latency is defined, a brokers may be responsible for maintaining information about resources shared by a group of nodes that are close to each other, with the set of nodes assigned to a broker being determined by the broker's location. In this paper, we present a broker-placement algorithm that finds a suitable location for a new broker when some broker is overloaded in such a way that some of the nodes are reassigned from the overloaded to the new broker. With latency as a metric, an overlay network can be embedded in an Euclidean space R^d, and our algorithm amounts to an optimization problem of selecting a suitable region in R^d for broker-placement, where a region represents equivalent broker locations. Our algorithm guarantees that if suitable regions exist, one of them will be found. The worst-case complexity of the algorithm is O(n^d^+^1) with n the number of nodes that may be assigned to the new broker, which is optimal up to a linear factor in n. We further show a simple optimization that brings down the complexity of the algorithm to a linear function of n in most of the cases. The linear complexity of the broker-placement algorithm is confirmed in a series of experiments on a real dataset. In addition, the performance of our broker-placement algorithm is compared to the performance of a naive approach, and it turns out that in a system with one million servers and one hundred brokers, our broker-placement algorithm is roughly 150 times more efficient.","Title: Decentralized group formation.\nYear: 2014\n\nAbstract: Imagine a network of entities, being it replica servers aiming to minimize the probability of data loss, players of online team-based games and tournaments, or companies that look into co-branding opportunities. The objective of each entity in any of these scenarios is to find a few suitable partners to help them achieve a shared goal: replication of the data for fault tolerance, winning the game, successful marketing campaign. All information attainable by the entities is limited to the profiles of other entities that can be used to assess the pairwise fitness. How can they create teams without help of any centralized component and without going into each other’s way? We propose a decentralized algorithm that helps nodes in the network to form groups of a specific size. The protocol works by finding an approximation of a weighted k-clique matching of the underlying graph of assessments. We discuss the basic version of the protocol, and explain how dissemination via gossiping helps in improving its scalability. We evaluate its performance through extensive simulations.","Title: From proximity sensing to spatio-temporal social graphs\nYear: 2014\n\nAbstract: Understanding the social dynamics of a group of people can give new insights into social behavior. Physical proximity between individuals results from the interactions between them. Hence, measuring physical proximity is an important step towards a better understanding of social behavior. We discuss a novel approach to sense proximity from within the social dynamics. Our primary objective is to construct a spatio-temporal social graph from noisy proximity data. We address the technical and algorithmic challenges of measuring proximity reliably and accurately. Simulations and real world experiments demonstrate the feasibility and scalability of our approach. Our algorithms doubles the sensitivity of proximity detections at the cost of a slight reduction in specificity.","Title: Scalable cooperative latency estimation\nYear: 2004\n\nAbstract: This paper discusses SCoLE, a scalable system to estimate Internet latencies. SCoLE is based on GNP, which models Internet latencies in an n-dimensional Euclidean space. In contrast to GNP and other GNP-based systems, however, SCoLE does not employ any global space whose parameters must typically be negotiated by the participating hosts. Instead, it allows each host to construct its \"'private\" space and model interhost latencies in that space. The private space parameters as well as the modeling algorithm can be adjusted on a per-host basis, which improves system flexibility. More importantly, the mutual independence of private spaces results in higher SCoLE scalability, which is bound neither by the global negotiation of space parameters nor by global knowledge of any kind. We show that latency estimates performed in different private spaces are highly correlated. This allows SCoLE to be used in large-scale applications where consistent latency estimates need to be performed simultaneously by many independent hosts.","Title: Scalable human-friendly resource names\nYear: 2001\n\nAbstract: Currently, Uniform Resource Locators (URLs) are used to name and access Web-based resources. However, URLs pose a significant scalability problem because they cannot be used to refer to replicated Web pages. The authors propose a new URI scheme called Human-Friendly Names (HFNs) to solve this scalability problem. HFNs are high-level names that are easy-to-use by humans and name Web resources in a location-independent way. This article describes a scalable HFN-to-URL resolution mechanism that is based on URNs and makes use of the Domain Name System (DNS) and the Globe Location Service.","Title: Autonomous Resource Selection for Decentralized Utility Computing\nYear: 2009\n\nAbstract: Many large-scale utility computing infrastructures comprise heterogeneous hardware and software resources. This raises the need for scalable resource selection services, which identify resources that match application requirements, and can potentially be assigned to these applications. We present a fully decentralized resource selection algorithm by which resources autonomously select themselves when their attributes match a query. An application specifies what it expects from a resource by means of a conjunction of (attribute, value-range) pairs, which are matched against the attribute values of resources. We show that our solution scales in the number of resources as well as in the number of attributes, while being relatively insensitive to churn and other membership changes such as node failures.","Title: Robust Overlays for Privacy-Preserving Data Dissemination over a Social Graph\nYear: 2012\n\nAbstract: A number of recently proposed systems provide secure and privacy-preserving data dissemination by leveraging pre-existing social trust relations and effectively mapping them into communication links. However, as we show in this paper, the underlying trust graph may not be optimal as a communication overlay. It has relatively long path lengths and it can be easily partitioned in scenarios where users are unavailable for a fraction of time. Following this observation, we present a method for improving the robustness of trust-based overlays. Essentially, we start with an overlay derived from the trust graph and evolve it in a privacy-preserving fashion into one that lends itself to data dissemination. The experimental evaluation shows that our approach leads to overlays that are significantly more robust under churn, and exhibit lower path lengths than the underlying trust graph.","Title: The Design and Evaluation of a Self-Organizing Superpeer Network\nYear: 2010\n\nAbstract: Superpeer architectures exploit the heterogeneity of nodes in a peer-to-peer (P2P) network by assigning additional responsibilities to higher capacity nodes. In the design of a superpeer network for file sharing, several issues have to be addressed: how client peers are related to superpeers, how superpeers locate files, how the load is balanced among the superpeers, and how the system deals with node failures. In this paper, we introduce a self-organizing superpeer network architecture (SOSPNet) that solves these issues in a fully decentralized manner. SOSPNet maintains a superpeer network topology that reflects the semantic similarity of peers sharing content interests. Superpeers maintain semantic caches of pointers to files, which are requested by peers with similar interests. Client peers, on the other hand, dynamically select superpeers offering the best search performance. We show how this simple approach can be employed not only to optimize searching, but also to solve generally difficult problems encountered in P2P architectures such as load balancing and fault tolerance. We evaluate SOSPNet using a model of the semantic structure derived from eight-month traces of two large file-sharing communities. The obtained results indicate that SOSPNet achieves close-to-optimal file search performance, quickly adjusts to changes in the environment (node joins and leaves), survives even catastrophic node failures, and efficiently distributes the system load taking into account superpeer capacities.","Title: Merging ultra-low duty cycle networks\nYear: 2011\n\nAbstract: Energy is the scarcest resource in ad-hoc wireless networks, particularly in wireless sensor networks requiring a long lifetime. Intermittently switching the radio on and off is widely adopted as the most effective way to keep energy consumption low. This, however, prevents the very goal of communication, unless nodes switch their radios on at synchronized intervals, a rather nontrivial coordination task. In this paper we address the problem of synchronizing node radios to a single universal schedule in very large scale wireless ad-hoc networks. More specifically, we focus on how independently synchronized clusters of nodes can detect each other and merge to a common radio schedule. Our main contributions consist in identifying the fundamental subproblems that govern cluster merging, providing a detailed comparison of the respective policies and their combinations, and supporting them by extensive simulation. Energy consumption, convergence speed, and network scalability have been the driving factors in our evaluation. The proposed policies are extensively tested in networks of up to 4,096 nodes. Our work is based on the GMAC protocol, a gossip-based MAC protocol for wireless ad-hoc networks.","Title: Decentralized Network-Level Synchronization in Mobile Ad Hoc Networks.\nYear: 2016\n\nAbstract: Energy is the scarcest resource in ad hoc wireless networks, particularly in wireless sensor networks requiring a long lifetime. Intermittently switching the radio on and off is widely adopted as the most effective way to keep energy consumption low. This, however, prevents the very goal of communication, unless nodes switch their radios on at synchronized intervals—a rather nontrivial coordination task. In this article, we address the problem of synchronizing node radios to a single universal schedule in wireless mobile ad hoc networks that can potentially consist of thousands of nodes. More specifically, we are interested in operating the network with duty cycles that can be less than 1p of the total cycle time. We identify the fundamental issues that govern cluster merging and provide a detailed comparison of various policies using extensive simulations based on a variety of mobility patterns. We propose a specific scheme that allows a 4,000-node network to stay synchronized with a duty cycle of approximately 0.7p. Our work is based on an existing, experimental MAC protocol that we use for real-world applications and is validated in a real network of around 120 mobile nodes.","Title: GDCluster: A General Decentralized Clustering Algorithm\nYear: 2015\n\nAbstract: In many popular applications like peer-to-peer systems, large amounts of data are distributed among multiple sources. Analysis of this data and identifying clusters is challenging due to processing, storage, and transmission costs. In this paper, we propose GDCluster, a general fully decentralized clustering method, which is capable of clustering dynamic and distributed data sets. Nodes continuously cooperate through decentralized gossip-based communication to maintain summarized views of the data set. We customize GDCluster for execution of the partition-based and density-based clustering methods on the summarized views, and also offer enhancements to the basic algorithm. Coping with dynamic data is made possible by gradually adapting the clustering model. Our experimental evaluations show that GDCluster can discover the clusters efficiently with scalable transmission cost, and also expose its supremacy in comparison to the popular method LSP2P.","Title: Proximity Graphs for Crowd Movement Sensors.\nYear: 2015\n\nAbstract: Sensors are now common, they span over different applications, different purposes and some over large geospatial areas. Most data produced by these sensors needs to be linked to the physical location of the sensor itself. By using the location of a sensor we can construct (mathematically) proximity graphs that have the sensors as nodes. These graphs have a wide variety of applications including visualization, packet routing, and spatial data analysis.We consider a sensor network that measures detections of WiFi packets transmitted by devices, such as smartphones. One important feature of sensors is given by the range in which they can gather data. Algorithms that build proximity graphs do not take this radius into account.We present an approach to building proximity graph that takes sensor position and radius as input. Our goal is to construct a graph that contains edges between pairs of sensors that are correlated to crowd movements, reflecting paths that individuals are likely to take. Because we are considering crowd movement, it gives us the unique opportunity to construct graphs that show the connections between sensors using consecutive detections of the same device. We show that our approach is better than ones that are based on the positioning of sensors only.","Title: Filters for Wi-Fi Generated Crowd Movement Data.\nYear: 2015\n\nAbstract: Cities represent large groups of people that share a common infrastructure, common social groups and/or common interests. With the development of new technologies current cities aim to become what is known as smart cities, in which all the small details of these large constructs are controlled to better improve the quality of life of its inhabitants. One of the important gears that powers a city is given by traffic, be it vehicular or pedestrian. As such traffic is closely related to all other activities that take place inside of a city. Understanding traffic is still a difficult process as we have to be able to not only measure it in the sense of how many people are using a particular path but also in analyzing where people are going and when, while still maintaining individual privacy. And all this has to be done at a scale that would cover most if not all individuals in a city.With the high increase in smartphones adoption we can reliably assume that a large part of the population in cities are carrying with them, at all times, at least one Wi-Fi enabled device. Because Wi-Fi devices are regularly transmitting signals we can rely on these devices to detect individual's movements unobtrusively without identifying or tracking any particular individual. Special sensors that monitor Wi-Fi frequencies can be placed around a city to gather data that can later be used to identify patterns in the traffic flows.We present a set of filters that can be used to minimize the amount of data needed for processing and without negatively impacting the result or the information that can be extracted from this data. Part of the filters we present can be deployed at the sensor level, making the entire system more scalable, while a different part can be executed before data processing thus enabling real time information extraction and a broader temporal and spatial range for data analysis. Some of these filters are particular to Wi-Fi but some of them can be applied to any detection system.","Title: Presumably Simple: Monitoring Crowds Using WiFi\nYear: 2016\n\nAbstract: Crowd Monitoring is receiving much attention. An increasingly popular technique is to scan for mobile devices, notably smartphones. We take a look at scanning for such devices by recording WiFi packets. Although research on capturing crowd patterns using WiFi detections has been done, there are not many published results when it comes to tracking movements. This is not surprising when realizing that the data provided by WiFi scanners is susceptible to many seemingly erroneous and missed detections, caused by the use of randomized network addresses, overlap between scanners, high variance in WiFi detection ranges, among other sources. In this paper, we investigate various techniques for cleaning up sets of raw detections to sets that can subsequently be used for crowd analytics. To this end, we introduce two different quality metrics to measure the effects of applying the various techniques. We test our approach using a data set collected from 27 WiFi scanners spread across the downtown area of a Dutch city where at that time a 3-day multi-stage festival took place attended by some 130,000 people.","Title: A brief introduction to distributed systems.\nYear: 2016\n\nAbstract: Distributed systems are by now commonplace, yet remain an often difficult area of research. This is partly explained by the many facets of such systems and the inherent difficulty to isolate these facets from each other. In this paper we provide a brief overview of distributed systems: what they are, their general design goals, and some of the most common types.","Title: Towards decisive garments for heat stress risk detection.\nYear: 2016\n\nAbstract: One of the numerous applications of wearable computers is providing safety in occupations where heat-related injuries are prevalent. Core temperature, as a parameter that cannot be measured by on-body sensors is a variable that is specifically interesting for realizing such applications. In the context of the design of a sensor-shirt that can be used by firefighters, in this paper we study the importance of different types of sensor measurements and their placement for estimating core temperature. We propose a model for inferring the dangerous states of core temperature. Our evaluation results show that our model can to a great extent estimate hazardous situations caused by heat accumulation.","Title: Using Performance Forecasting to Accelerate Elasticity.\nYear: 2015\n\nAbstract: Cloud computing facilitates dynamic resource provisioning. The automation of resource management, known as elasticity, has been subject to much research. In this context, monitoring of a running service plays a crucial role, and adjustments are made when certain thresholds are crossed. On such occasions, it is common practice to simply add or remove resources. In this paper we investigate how we can predict the performance of a service to dynamically adjust allocated resources based on predictions. In other words, instead of “repairing” because a threshold has been crossed, we attempt to stay ahead and allocate an optimized amount of resources in advance. To do so, we need to have accurate predictive models that are based on workloads. We present our approach, based on the Universal Scalability Law, and discuss initial experiments.","Title: Exploiting Density to Track Human Behavior in Crowded Environments.\nYear: 2017\n\nAbstract: For the Internet of Things to be people-centered, things need to identify when people and their things are nearby. In this article, we present the design, implementation, and deployment of a positioning system based on mobile and fixed inexpensive proximity sensors that we use to track when individuals are close to an instrumented object or placed at certain points of interest. To overcome loss of data between mobile and fixed sensors due to crowd density, traditional approaches are extended with mobile-to-mobile proximity information. We tested our system in a museum crowded with thousands of visitors, showing that measurement accuracy increases in the presence of more individuals wearing a proximity sensor. Furthermore, we show that density information can be leveraged to study the behavior of the visitors, for example, to track the popularity of points of interest, and the flow and distribution of visitors across floors.","Title: Spaceprint: a Mobility-based Fingerprinting Scheme for Public Spaces.\nYear: 2017\n\nAbstract: In this paper, we address the problem of how automated situation-awareness can be achieved by learning real-world situations from ubiquitously generated mobility data. Without semantic input about the time and space where situations take place, this turns out to be a fundamental challenging problem. Uncertainties also introduce technical challenges when data is generated in irregular time intervals, being mixed with noise, and errors. Purely relying on temporal patterns observable in mobility data, in this paper, we propose Spaceprint, a fully automated algorithm for finding the repetitive pattern of similar situations in spaces. We evaluate this technique by showing how the latent variables describing the category, and the actual identity of a space can be discovered from the extracted situation patterns. Doing so, we use different real-world mobility datasets with data about the presence of mobile entities in a variety of spaces. We also evaluate the performance of this technique by showing its robustness against uncertainties.","Title: Automated Lane Detection in Crowds using Proximity Graphs.\nYear: 2017\n\nAbstract: Studying the behavior of crowds is vital for understanding and predicting human interactions in public areas. Research has shown that, under certain conditions, large groups of people can form collective behavior patterns: local interactions between individuals results in global movements patterns. To detect these patterns in a crowd, we assume each person is carrying an on-body device that acts a local proximity sensor, e.g., smartphone or bluetooth badge, and represent the texture of the crowd as a proximity graph. Our goal is extract information about crowds from these proximity graphs. In this work, we focus on one particular type of pattern: lane formation. We present a formal definition of a lane, proposed a simple probabilistic model that simulates lanes moving through a stationary crowd, and present an automated lane-detection method. Our preliminary results show that our method is able to detect lanes of different shapes and sizes. We see our work as an initial step towards rich pattern recognition using proximity graphs.","Title: Inferring the Social-Connectedness of Locations from Mobility Data.\nYear: 2017\n\nAbstract: An often discriminating feature of a location is its social character or how well its visitors know each other. In this paper, we address the question of how we can infer the social contentedness of a location by observing the presence of mobile entities in it. We study a large number of mobility features that can be extracted from visits to a location. We use these features for predicting the social tie strengths of the device owners present in the location at a given moment in time, and output an aggregate score of social connectedness for that location. We evaluate this method by testing it on a real-world dataset. Using a synthetically modified version of this dataset, we further evaluate its robustness against factors that normally degrade the quality of such ubiquitously collected data (e.g. noise, sampling frequency). In each case, we found that the accuracy of the proposed method highly outperforms that of a state-of-the-art baseline methodology.","Title: A Survey of Techniques for Automatically Sensing the Behavior of a Crowd.\nYear: 2018\n\nAbstract: Crowd-centric research is receiving increasingly more attention as datasets on crowd behavior are becoming readily available. We have come to a point where many of the models on pedestrian analytics introduced in the last decade, which have mostly not been validated, can now be tested using real-world datasets. In this survey, we concentrate exclusively on automatically gathering such datasets, which we refer to as sensing the behavior of pedestrians. We roughly distinguish two approaches: one that requires users to explicitly use local applications and wearables, and one that scans the presence of handheld devices such as smartphones. We come to the conclusion that despite the numerous reports in popular media, relatively few groups have been looking into practical solutions for sensing pedestrian behavior. Moreover, we find that much work is still needed, in particular when it comes to combining privacy, transparency, scalability, and ease of deployment. We report on over 90 relevant articles and discuss and compare in detail 30 reports on sensing pedestrian behavior.","Title: Identifying Movements in Noisy Crowd Analytics Data\nYear: 2018\n\nAbstract: Privacy-preserved tracking of WiFi-enabled devices such as smartphones offers a highly scalable solution for large-scale crowd movement studies. However, extracting knowledge out of pedestrian-tracking data acquired this way is not simple. This is, generally, due to the inherent inaccuracy of the measurement technique. Segmenting an individual's trajectory data into periods of stops and moves is a fundamental step in analyzing crowds' movement. Such distinctions allow us to answer advanced questions regarding visited locations or even social behavior. Algorithms previously designed for distinguishing movements from stay periods, assume datasets are gathered using GPS, which offers precise positioning. WiFi tracking, however, does not offer such precision. The location of devices can at best be reduced to a large area around the WiFi scanner. In this paper, we study a set of established algorithms for detecting periods of stops and moves from GPS-based datasets and their applicability to WiFi-based data. Consequently, we propose possible improvements to such algorithms considering the inherent characteristics of WiFi tracking data.","Title: Identifying Stops and Moves in WiFi Tracking Data.\nYear: 2018\n\nAbstract: There are multiple methods for tracking individuals, but the classical ones such as using GPS or video surveillance systems do not scale or have large costs. The need for large-scale tracking, for thousands or even millions of individuals, over large areas such as cities, requires the use of alternative techniques. WiFi tracking is a scalable solution that has gained attention recently. This method permits unobtrusive tracking of large crowds, at a reduced cost. However, extracting knowledge from the data gathered through WiFi tracking is not simple, due to the low positional accuracy and the dependence on signals generated by the tracked device, which are irregular and sparse. To facilitate further data analysis, we can partition individual trajectories into periods of stops and moves. This abstraction level is fundamental, and it opens the way for answering complex questions about visited locations or even social behavior. Determining stops and movements has been previously addressed for tracking data gathered using GPS. GPS trajectories have higher positional accuracy at a fixed, higher frequency as compared to trajectories obtained through WiFi. However, even with the increase in accuracy, the problem, of separating traces in periods of stops and movements, remains similar to the one we encountered for WiFi tracking. In this paper, we study three algorithms for determining stops and movements for GPS-based datasets and explore their applicability to WiFi-based data. We propose possible improvements to the best-performing algorithm considering the specifics of WiFi tracking data.","Title: On the Run-Time Dynamics of a Peer-to-Peer Evolutionary Algorithm\nYear: 2008\n\nAbstract: In this paper we propose an improvement on a fully distributed Peer-to-Peer (P2P) Evolutionary Algorithm (EA) based on autonomous selection. Autonomous selection means that individuals decide on their own state of reproduction and survival without any central control, using instead estimations about the global population state for decision making. The population size varies at run-time as a consequence of such a decentralized reproduction and death of individuals. In order to keep it stable, we propose a self-adjusting mechanism which has been shown successful in three different search landscapes. Key are the estimations about fitness and size of the population as provided by a gossiping algorithm. Such an algorithm requires several rounds to collect the information while the individuals have to wait for synchronization. As an improvement, we propose a completely asynchronous EA which does not need waiting times. The results show that our approach outperforms quantitatively the execution time of the synchronous version.","Title: k-Anonymous Crowd Flow Analytics\nYear: 2020\n\nAbstract: Measuring pedestrian dynamics using the signals sent from smartphones has become popular. Notably, Wi-Fi-based systems are currently widely deployed. However, many such systems have also become subject to serious debate due to privacy infringement. For some time, secure hashing of a smartphone's unique MAC address was considered to be sufficient, yet this method has been overruled by Europe's General Data Protection Regulation which states that an individual should not be identifiable from any dataset without explicit prior consent. In this paper, we propose a novel anonymization technique that essentially anonymizes detected smartphones immediately at the sensor before any data on such a detection is stored for further analysis. Our solution borrows from the notion of k-anonymity, while avoiding its well-known drawbacks that lead to de-anonymization. Moreover, while ensuring what we coin detection k-anonymity, we also ensure high accuracy of counting measures when dealing with realistic pedestrian flows within crowds. We evaluate our solution both in a simulated environment and in a realistic environment reproducing real-life settings.","Title: DEEPCASE: Semi-Supervised Contextual Analysis of Security Events\nYear: 2022\n\nAbstract: Security monitoring systems detect potentially malicious activities in IT infrastructures, by either looking for known signatures or for anomalous behaviors. Security operators investigate these events to determine whether they pose a threat to their organization. In many cases, a single event may be insufficient to determine whether certain activity is indeed malicious. Therefore, a security operator frequently needs to correlate multiple events to identify if they pose a real threat. Unfortunately, the vast number of events that need to be correlated often overload security operators, forcing them to ignore some events and, thereby, potentially miss attacks. This work studies how to automatically correlate security events and, thus, automate parts of the security operator workload. We design and evaluate DEEPCASE, a system that leverages the context around events to determine which events require further inspection. This approach reduces the number of events that need to be inspected. In addition, the context provides valuable insights into why certain events are classified as malicious. We show that our approach automatically filters 86.72% of the events and reduces the manual workload of security operators by 90.53%, while underestimating the risk of potential threats in less than 0.001% of cases."],"string":"[\n \"Title: Secure peer sampling\\nYear: 2010\\n\\nAbstract: Gossiping has been identified as a useful building block for the development of large-scale, decentralized collaborative systems. With gossiping, individual nodes periodically interact with random partners, exchanging information about their local state; yet, they may globally provide several useful services, such as information diffusion, topology management, monitoring, load-balancing, etc. One fundamental building block for developing gossip protocols is peer sampling, which provides nodes with the ability to sample the entire population of nodes in order to randomly select a gossip partner. In existing implementations, however, one fundamental aspect is neglected: security. Byzantine nodes may subvert the peer sampling service and bias the random selection process, for example, by increasing the probability that a fellow malicious node is selected instead of a random one. The contribution of this paper is an extension to existing peer sampling protocols with a detection mechanism that identifies and blacklists nodes that are suspected of behaving maliciously. An extensive experimental evaluation shows that our extension is efficient in dealing with a large number of malicious nodes.\",\n \"Title: Group Monitoring in Mobile Ad-Hoc Networks.\\nYear: 2009\\n\\nAbstract: Maintaining bonds of cohesion between members of small groups in densely populated venues (e.g., a family in an amusement park, or some friends in a stadium) is increasingly gaining interest, both as a safety measure against malicious activity and as a convenient tool to prevent group splitting. Note that the use of mobile phones is often ruled out in such scenarios, due to extreme network load. Current solutions are typically based on custom installations of antennas, centralized control, and user devices with high transmission power. In this work we propose a novel method for anonymously spreading presence information among group members in dense environments, based on a completely decentralized mobile ad hoc network approach. Our system operates independently of any infrastructure and is targetted at resource constrained, inexpensive and expendable user devices. Quite importantly, our system protects the privacy of its users, both for their safety and for ethical reasons.\",\n \"Title: An experimental evaluation of self-managing availability in shared data spaces\\nYear: 2007\\n\\nAbstract: With its decoupling of processes in space and time, the shared data space model has proven to be a well-suited solution for developing distributed component-based systems. However, as in many distributed applications, functional and extra-functional aspects are still interwoven in components. In this paper, we address how shared data spaces can support the separation of concerns. In particular, we present a solution that allows developers to merely specify availability requirements for data tuples, while the underlying middleware evaluates various distribution and replication policies in order to select the one that meets these requirements best. Moreover, in our approach, the middleware continuously monitors the behavior of application and system components, and switches to different policies if this would lead to better results. We describe our approach, along with the design of a prototype implementation and its quantitative evaluation.\",\n \"Title: A scalable middleware solution for advanced wide-area web services\\nYear: 1999\\n\\nAbstract: To alleviate scalability problems in the Web, many researchers concentrate on how to incorporate advanced caching and replication techniques. Many solutions incorporate object-based techniques. In particular, Web resources are considered as distributed objects offering a well-defined interface. We argue that most proposals ignore two important aspects. First, there is little discussion on what kind of coherence should be provided. Proposing specific caching or replication solutions makes sense only if we know what coherence model they should implement. Second, most proposals treat all Web resources alike. Such a one-size-fits-all approach will never work in a wide-area system. We propose a solution in which Web resources are encapsulated in physically distributed shared objects. Each object should not only encapsulate state and operations, but also the policy by which its state is distributed, cached, replicated, migrated, etc.\",\n \"Title: Offloading servers with collaborative video on demand\\nYear: 2008\\n\\nAbstract: The peer-to-peer (P2P) paradigm provides a data distribution model that may be attractive for Video on Demand (VoD) as it allows to decrease the costs and to increase the scalability of video distribution. However, VoD is more challenging for P2P technology than file sharing or live streaming, and so, practically feasible VoD systems proposed to date rely on a backend server infrastructure as a fail-over solution. In this paper we investigate how the dependency on servers can be decreased by optimizing the video piece-selection strategy and by allowing multiple peers to form a collaboration for obtaining a single video. In a set of simulations of a trace-based system model we show that for systems such as YouTube the proposed optimizations would result in savings of as much as 70% of the server bandwidth. These simulation results confirm the conclusions of an analytical study of our optimizations, the essential part of which is also included in this paper.\",\n \"Title: Hybrid dissemination: adding determinism to probabilistic multicasting in large-scale P2P systems\\nYear: 2007\\n\\nAbstract: Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes.\",\n \"Title: Latency-Driven Replica Placement\\nYear: 2005\\n\\nAbstract: This paper presents HotZone, an algorithm to place replicas in a wide-area network such that the client-to-replica latency is minimized. Similar to the previously proposed HotSpot algorithm, HotZone places replicas on nodes that along with their neighboring nodes generate the highest load. In contrast to HotSpot, however, HotZone provides nearly-optimal results by considering overlapping neighborhoods. HotZone relies on a geometric model of Internet latencies, which effectively reduces the cost of placing K replicas among N potential replica locations from O(N^2) to O(N · max(logN, K)).\",\n \"Title: Gossiping in distributed systems\\nYear: 2007\\n\\nAbstract: Gossip-based algorithms were first introduced for reliably disseminating data in large-scale distributed systems. However, their simplicity, robustness, and flexibility make them attractive for more than just pure data dissemination alone. In particular, gossiping has been applied to data aggregation, overlay maintenance, and resource allocation. Gossiping applications more or less fit the same framework, with often subtle differences in algorithmic details determining divergent emergent behavior. This divergence is often difficult to understand, as formal models have yet to be developed that can capture the full design space of gossiping solutions. In this paper, we present a brief introduction to the field of gossiping in distributed systems, by providing a simple framework and using that framework to describe solutions for various application domains.\",\n \"Title: Gossip-based peer sampling\\nYear: 2007\\n\\nAbstract: Gossip-based communication protocols are appealing in large-scale distributed applications such as information dissemination, aggregation, and overlay topology management. This paper factors out a fundamental mechanism at the heart of all these protocols: the peer-sampling service. In short, this service provides every node with peers to gossip with. We promote this service to the level of a first-class abstraction of a large-scale distributed system, similar to a name service being a first-class abstraction of a local-area system. We present a generic framework to implement a peer-sampling service in a decentralized manner by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself. Our framework generalizes existing approaches and makes it easy to discover new ones. We use this framework to empirically explore and compare several implementations of the peer-sampling service. Through extensive simulation experiments we show that---although all protocols provide a good quality uniform random stream of peers to each node locally---traditional theoretical assumptions about the randomness of the unstructured overlays as a whole do not hold in any of the instances. We also show that different design decisions result in severe differences from the point of view of two crucial aspects: load balancing and fault tolerance. Our simulations are validated by means of a wide-area implementation.\",\n \"Title: Securely Replicated Web Documents\\nYear: 2005\\n\\nAbstract: In order to achieve better scalability and reduce latency in handling user requests, many Web applications make extensive use of data replication through caches and Content Delivery Networks. However, in such scenarios data is often placed on untrusted hosts. As a result, existing replication mechanisms open a wide class vulnerabilities, ranging from denial of service to content masquerading. In this paper we present an architecture that combines data content, replication strategies and security in one unified object model and offers integrity guarantees for Web documents replicated on non secure servers.\",\n \"Title: Identifying Malicious Peers Before It's Too Late: A Decentralized Secure Peer Sampling Service\\nYear: 2007\\n\\nAbstract: Many unstructured peer to peer (P2P) systems rely on a Peer Sampling Service (PSS) that returns randomly sampled nodes from the population comprising the system. PSS protocols are often implemented using \\\"gossiping\\\" approaches in which connected nodes exchange their links in a randomized way. However, such services can be defeated easily by malicious nodes executing \\\"hub attacks\\\" which distort the PSS such that all nodes in the network, ultimately, only gain access to malicious nodes. From this leading status - i.e. being a \\\"hub\\\" - the malicious nodes can affect the overlay in several ways, ranging from total network disruption to obtaining an application dependent advantage. We present a completely distributed defense against such attacks and give results from simulation experiments. The approach is generic as it is independent of the adopted PSS implementation.\",\n \"Title: Collaborative filtering using random neighbours in peer-to-peer networks\\nYear: 2009\\n\\nAbstract: Traditionally, collaborative filtering (CF) algorithms used for recommendation operate on complete knowledge. This makes these algorithms hard to employ in a decentralized context where not all users' ratings can be available at all locations. In this paper we investigate how the well-known neighbourhood-based CF algorithm by Herlocker et al. operates on partial knowledge; that is, how many similar users does the algorithm actually need to produce good recommendations for a given user, and how similar must those users be. We show for the popular MovieLens 1,000,000 and Jester datasets that sufficiently good recommendations can be made based on the ratings of a neighbourhood consisting of a relatively small number of randomly selected users.\",\n \"Title: Enforcing Data Integrity in Very Large Ad Hoc Networks\\nYear: 2007\\n\\nAbstract: Ad hoc networks rely on nodes forwarding each other's packets, making trust and cooperation key issues for ensuring network performance. As long as all nodes in the network belong to the same organization and share the same goal (in military scenarios, for example), it can generally be expected that all nodes can be trusted. However, as wireless technology becomes more commonplace, we can foresee the appearance of very large, heterogeneous networks where the intentions of neighboring nodes are unknown. Without any security measures in place, any node is capable of compromising the integrity of the data it forwards. Our goal in this paper is to ensure the integrity of the data being disseminated without resorting to complex and expensive solutions. We achive this by discouraging malicious behavior in two ways: a) enforcing integrity checks close to the source and b) refusing to communicate with obviously malicious nodes. We find that by having nodes sample their traffic for corrupted messages, malicious nodes can be identified with high accuracy, in effect transforming our collection o f nodes into a self-policing network.\",\n \"Title: Managing clouds: a case for a fresh look at large unreliable dynamic networks\\nYear: 2006\\n\\nAbstract: Peer-to-peer (P2P) protocols have proven efficient to provide scalable support to many large-scale distributed applications, successfully coping with unreliability and dynamics. However, to exploit them in a wider range of environments, such as very large-scale networks of smartphones or set-top boxes, it is imperative to make P2P protocols manageable: we need to be able to start, bootstrap and stop protocols, and assign resources dynamically. In this paper we present a general-purpose framework aimed to support several fully distributed applications running independently over a very large scale and dynamic pool of resources. We call this resource pool a cloud. The basic idea of the framework is a declarative application suit description, that describes what applications should be running on what resources, and a middleware that makes sure the currently available and dynamic cloud self-organizes into the configuration represented by the description, creating the subclouds that are assigned to applications. The middleware also provides additional functionality, such as bootstrapping overlay networks, to support the applications. Our preliminary ideas on the implementation rely on various gossip-based protocols, that are applied to form the subclouds and to implement bootstrapping, monitoring and control services. Most of all, this position paper sets an exciting research agenda to fully exploit the possibilities offered by very large scale dynamic networks.\",\n \"Title: PolderCast: fast, robust, and scalable architecture for P2P topic-based pub/sub\\nYear: 2012\\n\\nAbstract: We propose PolderCast, a P2P topic-based Pub/Sub system that is (a) fault-tolerant and robust, (b) scalable w.r.t the number of nodes interested in a topic and number of topics that nodes are interested in, and (c) fast in terms of dissemination latency while (d) attaining a low communication overhead. This combination of properties is provided by an implementation that blends deterministic propagation over maintained rings with probabilistic dissemination following a limited number of random shortcuts. The rings are constructed and maintained using gossiping techniques. The random shortcuts are provided by two distinct peer-sampling services: Cyclon generates purely random links while Vicinity produces interest-induced random links. We analyze PolderCast and survey it in the context of existing approaches. We evaluate PolderCast experimentally using real-world workloads from Twitter and Facebook traces. We use widely renowned Scribe [5] as a baseline in a number of experiments. Robustness with respect to node churn is evaluated through traces from the Skype superpeer network. We show that the experimental results corroborate all of the above properties in settings of up to 10K nodes, 10K topics, and 5K topics per-node.\",\n \"Title: Scalable analysis for large social networks: the data-aware mean-field approach\\nYear: 2012\\n\\nAbstract: Studies on social networks have proved that endogenous and exogenous factors influence dynamics. Two streams of modeling exist on explaining the dynamics of social networks: 1) models predicting links through network properties, and 2) models considering the effects of social attributes. In this interdisciplinary study we work to overcome a number of computational limitations within these current models. We employ a mean-field model which allows for the construction of a population-specific model informed from empirical research for predicting links from both network and social properties in large social networks.. The model is tested on a population of conference coauthorship behavior, considering a number of parameters from available Web data. We address how large social networks can be modeled preserving both network and social parameters. We prove that the mean-field model, using a data-aware approach, allows us to overcome computational burdens and thus scalability issues in modeling large social networks in terms of both network and social parameters. Additionally, we confirm that large social networks evolve through both network and social-selection decisions; asserting that the dynamics of networks cannot singly be studied from a single perspective but must consider effects of social parameters.\",\n \"Title: Design Level Support for Parallel and Distributed Applications\\nYear: 1996\\n\\nAbstract: The growing interest in using a cluster of workstations as the target platform for high-performance applications, ha s again emphasized the need for support tools that can be used during application design. In this paper we present a graphical technique, calledADL-D, that allows a devel- oper to construct an application in terms of communicat- ing processes. The technique distinguishes itself from oth - ers by its use of highly orthogonal concepts, and the sup- port for automated code generation. Developers are en- couraged to concentrate on designing components in iso- lation, making the complex design space more manage- able than would otherwise be the case.ADL-D can be used from the early phases of application design through phases that concentrate on algorithmic design, and final imple- mentation on some target platform. Rather than present- ing details of ADL-D, we use it here as a vehicle for a more general discussion on design level support for parallel and distributed applications.\",\n \"Title: The peer sampling service: experimental evaluation of unstructured gossip-based implementations\\nYear: 2004\\n\\nAbstract: In recent years, the gossip-based communication model in large-scale distributed systems has become a general paradigm with important applications which include information dissemination, aggregation, overlay topology management and synchronization. At the heart of all of these protocols lies a fundamental distributed abstraction: the peer sampling service. In short, the aim of this service is to provide every node with peers to exchange information with. Analytical studies reveal a high reliability and efficiency of gossip-based protocols, under the (often implicit) assumption that the peers to send gossip messages to are selected uniformly at random from the set of all nodes. In practice -- instead of requiring all nodes to know all the peer nodes so that a random sample could be drawn -- a scalable and efficient way to implement the peer sampling service is by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself.This paper presents a generic framework to implement reliable and efficient peer sampling services. The framework generalizes existing approaches and makes it easy to introduce new ones. We use this framework to explore and compare several implementations of our abstraction. Through extensive experimental analysis, we show that all of them lead to different peer sampling services none of which is uniformly random. This clearly renders traditional theoretical approaches invalid, when the underlying peer sampling service is based on a gossip-based scheme. Our observations also help explain important differences between design choices of peer sampling algorithms, and how these impact the reliability of the corresponding service.\",\n \"Title: A distributed shared data space for personal health systems.\\nYear: 2006\\n\\nAbstract: Ubiquitous computing is a promising paradigm to support health care outside traditional care institutes. Sensor-based systems may continuously collect data on a person's health status and context, and provide immediate feedback or contact a remote physician. This paper presents a novel programming model to facilitate the development of such systems. The model, which has been inspired by tuple spaces, offers robustness for ad hoc mobile environments and explicit support for data streams\",\n \"Title: On the value of random opinions in decentralized recommendation\\nYear: 2006\\n\\nAbstract: As the amount of information available to users continues to grow, filtering wanted items from unwanted ones becomes a dominant task. To this end, various collaborative-filtering techniques have been developed in which the ratings of items by other users form the basis for recommending items that could be of interest for a specific person. These techniques are based on the assumption that having ratings from similar users improves the quality of recommendation. For decentralized systems, such as peer-to-peer networks, it is generally impossible to get ratings from all users. For this reason, research has focused on finding the best set of peers for recommending items for a specific person. In this paper, we analyze to what extent the selection of such a set influences the quality of recommendation. Our findings are based on an extensive experimental evaluation of the MovieLens data set applied to recommending movies. We find that, in general, a random selection of peers gives surprisingly good recommendations in comparison to very similar peers that must be discovered using expensive search techniques. Our study suggests that simple decentralized recommendation techniques can do sufficiently well in comparison to these expensive solutions.\",\n \"Title: Tribler: A Social-Based Peer-To-Peer System\\nYear: 2008\\n\\nAbstract: Most current peer-to-peer (P2P) file-sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes or interests may well be exploited in such systems in order to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm's main concepts such as taste buddies and friends, we have designed and implemented the TRIBLER P2P file-sharing system as a set of extensions to BitTorrent. We present and discuss the design of TRIBLER, and we show evidence that TRIBLER enables fast content discovery and recommendation at a low additional overhead, and a significant improvement in download performance. Copyright (c) 2007 John Wiley & Sons, Ltd.\",\n \"Title: Analysis of Caching and Replication Strategies for Web Applications\\nYear: 2007\\n\\nAbstract: Developers often use replication and caching mechanisms to enhance Web application performance. The authors present a qualitative and quantitative analysis of state-of-the art replication and caching techniques used to host Web applications. Their analysis shows that selecting the best mechanism depends heavily on data workload and requires a careful review of the application's characteristics. They also propose a technique for Web practitioners to compare different mechanisms' performance on their own.\",\n \"Title: Computer Science, Informatics, and the Networked World\\nYear: 2011\\n\\nAbstract: Many of today's students barely know what a desktop computer is, much less want to focus their studies on the traditional computer science curriculum. Instead, professors should consider a cross-disciplinary approach that crosses fences and helps students learn what's behind the networked world they live in.\",\n \"Title: The hidden pub/sub of spotify: (industry article)\\nYear: 2013\\n\\nAbstract: Spotify is a peer-assisted music streaming service that has gained worldwide popularity. Apart from providing instant access to over 20 million music tracks, Spotify also enhances its users' music experience by providing various features for social interaction. These are realized by a system using the widely-adopted pub/sub paradigm. In this paper we provide an interesting case study of a hybrid pub/sub system designed for real-time as well as offline notifications for Spotify users. We firstly describe a multitude of use cases where pub/sub is applied. Secondly, we study the design of its pub/sub system used for matching, disseminating and persisting billions of publications every day. Finally, we study pub/sub traffic collected from the production system, derive characterizations of the pub/sub workload, and show some interesting findings and trends.\",\n \"Title: Sandnet: network traffic analysis of malicious software\\nYear: 2011\\n\\nAbstract: Dynamic analysis of malware is widely used to obtain a better understanding of unknown software. While existing systems mainly focus on host-level activities of malware and limit the analysis period to a few minutes, we concentrate on the network behavior of malware over longer periods. We provide a comprehensive overview of typical malware network behavior by discussing the results that we obtained during the analysis of more than 100,000 malware samples. The resulting network behavior was dissected in our new analysis environment called Sandnet that complements existing systems by focusing on network traffic analysis. Our in-depth analysis of the two protocols that are most popular among malware authors, DNS and HTTP, helps to understand and characterize the usage of these prevalent protocols.\",\n \"Title: From Remote Objects to Physically Distributed Objects\\nYear: 1999\\n\\nAbstract: Present-day object-oriented middleware provides little support for the distribution, replication and caching of the state of a distributed object. This makes these platforms unsuitable for the development of large-scale distributed applications. We argue that the model of distributed objects on which these middleware platforms are based hinders the addition of comprehensive distribution and replication support to these platforms. We present an alternative view of distributed objects, in which objects are not only in control of the functional aspects of their implementation but also in control of their nonfunctional aspects, in particular, the distribution and replication of their state. We claim that a middleware platform based on this view of distributed objects is better suited for developing the large-scale applications of the future.\",\n \"Title: Technical challenges in market-driven automated service provisioning\\nYear: 2008\\n\\nAbstract: In today's practice, we see readily precomposed commercial service bundles, such as a spam-free email box, consisting of more elementary services like mail storage and a spam-filter. However, these bundles may be suboptimal from the customer's perspective in terms of price and/or the elementary services that constitute the bundle. It would be advantageous to the customer if a service bundle more closely fulfilled the customer's individual requirements, by selecting the most appropriate elementary services included in the bundle. Also, by obtaining the bundle from a consortium of suppliers, rather than just one single supplier, the elementary services of each supplier with the best cost/benefit ratio can be selected. To put this vision into reality, we need middleware facilitating the automated composition of multisupplier bundles out of basic commercial services available online. We take the stand that the business nature of commercial services imposes leading requirements on the technical design of the middleware. Most importantly, the middleware should be fair in the sense that no single supplier obtains a preferred position in terms of service selection to satisfy a specific customer need. Also, the middleware should be able to deal with alternative services as offered by many competing suppliers, not to speak about the combinatoric explosion, resulting from combining the available services into candidate services bundles. We present a list of problems to be solved to arrive at middleware for multi-supplier service selection, bundling and provisioning. Also, we review existing work, usable to build a fair and efficient middleware solution for commercial service provisioning.\",\n \"Title: A probabilistic replication and storage scheme for large wireless networks of small devices\\nYear: 2008\\n\\nAbstract: Nodes in wireless ad hoc networks are often limited in terms of resources, such as storage, power, and bandwidth. A downside of this is the fact that local storage at one node cannot accommodate the vast amount of data contained in the network. In this paper, we present SharedState, a scheme for storage, replication, and distribution of common-interest data in wireless networks of resource-constrained devices (e.g. sensor nodes or embedded devices). SharedState works under the assumption that individual nodes would greatly benefit from having access to the wealth of information in the network, but are unable to store it locally at once. SharedState strives to make data available to every node by providing local access to a subset of the whole collection of data items in the network at any moment in time and ensuring that this subset is updated periodically. This is accomplished by probabilistic propagation and replication of data items, ensuring the availability and persistence of information in the face of changing network conditions. We evaluate the performance of SharedState by studying the effectiveness with which nodes can gather information from the network. In addition, we optimize the bandwidth usage of our proposed solution by minimizing unnecessary communication based on feedback from the local neighborhood.\",\n \"Title: Characterizing Internet performance to support wide-area application development\\nYear: 2000\\n\\nAbstract: To help in our wide-area application development, we have done an informal study of the relation between wide-area latency, the number of routers, and geographical distance between Internet sites. We did this by performing ping and traceroute measurements between 19 sites distributed across the globe. Contrary to our expectation there is almost no correlation between distance, latency, and number of routers in the current Internet. To help further studies of these characteristics the problems of this pilot project are also described.\",\n \"Title: Simplified Distributed Programming With Micro Objects\\nYear: 2010\\n\\nAbstract: Developing large-scale distributed applications can be a daunting task. Object-based environments have attempted to alleviate problems by providing distributed objects that look like local objects. We advocate that this approach has actually only made matters worse, as the developer needs to be aware of many intricate internal details in order to adequately handle partial failures. The result is an increase of application complexity. We present an alternative in which distribution transparency is lessened in favor of clearer semantics. In particular, we argue that a developer should always be offered the unambiguous semantics of local objects, and that distribution comes from copying those objects to where they are needed. We claim that it is often sufficient to provide only small, immutable objects, along with facilities to group objects into clusters.\",\n \"Title: On hierarchical routing in wireless sensor networks\\nYear: 2009\\n\\nAbstract: Hierarchical routing is a promising approach for point-to-point routing with very small routing state. While there are many theoretical analyses and high-level simulations demonstrating its benefits, there has been little work to evaluate it in a realistic wireless sensor network setting. Based on numerous proposed hierarchical routing infrastructures, we develop a framework that captures the common characteristics of the infrastructures and identifies design points where the infrastructures differ. We then evaluate the implementation of the framework in TOSSIM and on a 60-node testbed. We demonstrate that from the practical perspective hierarchical routing is also an appealing routing approach for sensor networks. Despite only logarithmic routing state, it can offer low routing stretch: the average of ∼1.25 and the 99-th percentile of 2. Moreover, a hierarchical routing infrastructure can be autonomously bootstrapped and maintained by the nodes. By exploring the design points within our framework, the hierarchy maintenance protocol can optimize different metrics, such as the latency of bootstrapping and repairing the hierarchy after failures or the traffic volume, depending on the application requirements. Finally, we also identify a number of practical issues which we believe the applications employing hierarchical routing should be aware of.\",\n \"Title: EvAg: a scalable peer-to-peer evolutionary algorithm\\nYear: 2010\\n\\nAbstract: This paper studies the scalability of an Evolutionary Algorithm (EA) whose population is structured by means of a gossiping protocol and where the evolutionary operators act exclusively within the local neighborhoods. This makes the algorithm inherently suited for parallel execution in a peer-to-peer fashion which, in turn, offers great advantages when dealing with computationally expensive problems because distributed execution implies massive scalability. In this paper we show another advantage of this algorithm: We experimentally demonstrate that it scales up better than traditional alternatives even when executed in a sequential fashion. In particular, we analyze the behavior of several EAs on well-known deceptive trap functions with varying sizes and levels of deceptiveness. The results show that the new EA requires smaller optimal population sizes and fewer fitness evaluations to reach solutions. The relative advantage of the new EA is more outstanding as problem hardness and size increase. In some cases the new algorithm reduces the computational efforts of the traditional EAs by several orders of magnitude.\",\n \"Title: GlobeDB: autonomic data replication for web applications\\nYear: 2005\\n\\nAbstract: We present GlobeDB, a system for hosting Web applications that performs autonomic replication of application data. GlobeDB offers data-intensive Web applications the benefits of low access latencies and reduced update traffic. The major distinction in our system compared to existing edge computing infrastructures is that the process of distribution and replication of application data is handled by the system automatically with very little manual administration. We show that significant performance gains can be obtained this way. Performance evaluations with the TPC-W benchmark over an emulated wide-area network show that GlobeDB reduces latencies by a factor of 4 compared to non-replicated systems and reduces update traffic by a factor of 6 compared to fully replicated systems.\",\n \"Title: Gossip-Based Self-Management of a Recursive Area Hierarchy for Large Wireless SensorNets\\nYear: 2010\\n\\nAbstract: A recursive multihop area hierarchy has a number of applications in wireless sensor networks, the most common being scalable point-to-point routing, so-called hierarchical routing. In this paper, we consider the problem of maintaining a recursive multihop area hierarchy in large sensor networks. We present a gossip-based protocol, dubbed PL-Gossip, in which nodes, by using local-only operations and by periodically gossiping with their neighbors, collaboratively maintain such a hierarchy. Since the hierarchy is a complex distributed structure, PL-Gossip introduces special mechanisms for internode coordination and consistency enforcement. Yet, these mechanisms are seamlessly integrated within the basic gossiping framework. Through simulations and experiments with an actual embedded protocol implementation, we demonstrate that PL-Gossip maintains the hierarchy in a manner that addresses all the peculiarities of sensor networks. More specifically, it offers excellent opportunities for aggressive energy saving and facilitates provisioning energy harvesting infrastructure. In addition, it bootstraps and recovers the hierarchy after failures relatively fast while also being robust to message loss. Finally, it can seamlessly operate on real sensor node hardware in realistic deployment scenarios and can outperform existing state-of-the-art hierarchy maintenance protocols.\",\n \"Title: Sub-2-Sub: Self-Organizing Content-Based Publish Subscribe for Dynamic Large Scale Collaborative Networks\\nYear: 2006\\n\\nAbstract: In this paper, we address the problem of constructing scalable content-based publish/subscribe systems. Publish/subscribe sys- tems are asynchronous event-notification systems in which a pub- lished event is forwarded to exactly those nodes that have previously subscribed for that event. Subscriptions can range from a simple specification of merely the type of an event to a specification of the value ranges that an event's attributes can have. Notably the latter poses potential scalability problems. Structured peer-to-peer systems can provide scalable solutions to publish/subscribe systems with simple subscription patterns. For complex subscription types their applicability is less obvious. In this paper, we present SUB-2-SUB, a collaborative self-organizing pub- lish/subscribe system deploying an unstructured overlay network. SUB-2-SUB relies on an epidemic-based algorithm in which peers continuously exchange subscription information to get clustered to similar peers. In contrast to many existing approaches, SUB-2-SUB supports both value-based and interval-based subscriptions. Simu- lations of SUB-2-SUB on synthetic and reusable workloads convey its good properties in terms of routing efficiency, fairness, accuracy and efficiency. dation. space of the latter to the identifier space of the former. At one extreme, each attribute is associated with one specific peer. Although this provides efficient routing to interested subscribers, peers hosting popular attributes are quickly over- loaded. At the other end of the spectrum, in an attempt to discretize the ranges of attributes, a peer is made responsible for a specific (attribute, value) pair. In this case, attaining a scalable implementation for range subscriptions becomes problematic.\",\n \"Title: Prestige-based peer sampling service: interdisciplinary approach to secure gossip\\nYear: 2009\\n\\nAbstract: The Peer Sampling Service (PSS) has been proposed as a method to initiate and maintain the set of connections between nodes in unstructured peer to peer (P2P) networks. The PSS usually relies on gossip-style communication where participants exchange their links in a randomized way. However, the PSS network organization can be easily modified by malicious nodes running a \\\"hub attack\\\", in which they achieve a leading structural position. From this prestigious status, the malicious nodes can severely affect the overlay and achieve several application dependent advantages. We present a novel method to overcome this attack and provide results from simulation experiments that validate our claim. This method is inspired by a simple technique used to detect social leaders in firm's organizations that is based on the social (structural) \\\"prestige\\\" of actors.\",\n \"Title: Optimizing Peer Relationships in a Super-Peer Network\\nYear: 2007\\n\\nAbstract: Super-peer architectures exploit the heterogeneity of nodes in a P2P network by assigning additional responsi- bilities to higher-capacity nodes. In the design of a super- peer network for file sharing, several issues have to be ad- dressed: how client peers are related to super-peers, how super-peers locate files, how the load is balanced among the super-peers, and how the system deals with node failures. In this paper we introduce a self-organizing super-peer net- work architecture (SOSPNET) that solves these issues in a fully decentralized manner. SOSPNET maintains a super- peer network topology that reflects the semantic similarity of peers sharing content interests. Super-peers maintain se- mantic caches of pointers to files which are requested by peers with similar interests. Client peers, on the other hand, dynamically select super-peers offering the best search per- formance. We show how this simple approach can be em- ployed not only to optimize searching, but also to solve gen- erally difficult problems encountered in P2P architectures such as load balancing and fault tolerance. We evaluate SOSPNET using a model of the semantic structure derived from the 8-month traces of two large file-sharing communi- ties. The obtained results indicate that SOSPNET achieves close-to-optimal file search performance, quickly adjusts to changes in the environment (node joins and leaves), sur- vives even catastrophic node failures, and efficiently dis- tributes the system load taking into account peer capacities.\",\n \"Title: Wikipedia workload analysis for decentralized hosting\\nYear: 2009\\n\\nAbstract: We study an access trace containing a sample of Wikipedia's traffic over a 107-day period aiming to identify appropriate replication and distribution strategies in a fully decentralized hosting environment. We perform a global analysis of the whole trace, and a detailed analysis of the requests directed to the English edition of Wikipedia. In our study, we classify client requests and examine aspects such as the number of read and save operations, significant load variations and requests for nonexisting pages. We also review proposed decentralized wiki architectures and discuss how they would handle Wikipedia's workload. We conclude that decentralized architectures must focus on applying techniques to efficiently handle read operations while maintaining consistency and dealing with typical issues on decentralized systems such as churn, unbalanced loads and malicious participating nodes.\",\n \"Title: Distributed redirection for the World-Wide Web\\nYear: 2005\\n\\nAbstract: Replication in the World-Wide Web covers a wide range of techniques. Often, the redirection of a client browser towards a given replica of a Web page is performed after the client's request has reached the Web server storing the requested page. As an alternative, we propose to perform the redirection as close to the client as possible in a fully distributed and transparent manner. Distributed redirection ensures that we find a replica wherever it is stored and that the closest possible replica is always found first. By exploiting locality, we can keep latency low.\",\n \"Title: A Structured Design Technique for Distributed Programs\\nYear: 1998\\n\\nAbstract: A non-formal motivation and description is given ofADL- d, a graphical design technique for parallel and distributed software. ADL-d allows a developer to construct an appli- cation in terms of communicating processes. The technique distinguishes itself from others by its rigid orthogonal ap- proach to communication modeling, which is advantageous in many areas. Without being committed to one particular design method, ADL-d as a technique can be used from the early phases of application design through phases that con- centrate on algorithmic design, and final implementation on some target platform. In this paper, we discuss and motivate all ADL-d components, including recently incorporated fea- tures such as support for connection-oriented communica- tion, and support for modeling dynamically changing com- munication structures.\",\n \"Title: Group formation among peer-to-peer agents: learning group characteristics\\nYear: 2003\\n\\nAbstract: This paper examines the decentralized formation of groups within a peer-to-peer multi-agent system. More specifically, it frames group formation as a clustering problem, and examines how to determine cluster characteristics such as area and density in the absence of information about the entire data set, such as the number of points, the number of clusters, or the maximum distance between points, that are available to centralized clustering algorithms. We develop a method in which agents individually search for other agents with similar characteristics in a peer-to-peer manner. These agents group into small centrally controlled clusters which learn cluster parameters by examining and improving their internal composition over time. We show through simulation that this method allows us to find clusters of a wide variety of sizes without adjusting agent parameters.\",\n \"Title: Exploring extreme wireless distributed systems\\nYear: 2011\\n\\nAbstract: Modern distributed systems are increasingly relying on components that need to make use of wireless technology. Examples include subsystems implemented as wireless sensor networks or subsystems making use of mobile computing platforms. In this tutorial, we'll be looking closer into wireless-only distributed systems that are extreme in one or several of the following dimensions: their size in terms of the number of nodes, the resource limitations of those nodes (memory, compute power, energy budget), or the harshness of their environment (lossy channels, mobility). In particular, we'll be discussing issues related to turning such extreme distributed systems into robust ones, addressing questions like: how to set up and maintaining routing paths, how to reliably disseminate information, and how to realize very large ultra-low duty-cycled networks. In the meantime, we draw examples from systems that are aimed at directly supporting human beings.\",\n \"Title: Gossip-based clock synchronization for large decentralized systems\\nYear: 2006\\n\\nAbstract: Numerous large-scale decentralized systems assume loosely synchronized clocks. Existing time protocols have not been designed for deployment in such systems, since they are complex and require manual configuration. We present the Gossiping Time Protocol (GTP), a completely self-managing epidemic time synchronization algorithm for peer-to-peer networks. In GTP, each node synchronizes its time by gossiping with other nodes. The decisions regarding sample evaluation and gossiping frequency are purely local, yet they result in consistent behavior of the whole system. Large-scale experimental evaluation of a 64,500-node network emulated on 65 machines indicates high scalability and reasonable accuracy of GTP.\",\n \"Title: Replicating Web Applications On-Demand\\nYear: 2004\\n\\nAbstract: Many Web-based commercial services deliver their content using Web applications that generate pages dynamically based on user profiles, request parameters etc. The workload of these applications are often characterized by a large number of unique requests and a significant fraction of data updates. Hosting these applications drives the need for systems that replicates both the application code and its underlying data. We propose the design of such a system that is based on on-demand replication, where data units are replicated only to servers that access them often. This reduces the consistency overhead as updates are sent to a reduced number of servers. The proposed system allows complete replication transparency to the application, thereby allowing developers to build applications unaware of the underlying data replication. We show that the proposed techniques can reduce the client response time by a factor of 5 in comparison to existing techniques for a real-world e-commerce application used in the TPC-W benchmark. Furthermore, we evaluate our strategies for a wide range of workloads and show that on-demand replication performs better than centralized and fully replicated systems by reducing the average latency of read/write data accesses as well as the amount of bandwidth utilized to maintain data consistency.\",\n \"Title: Epidemic-Style management of semantic overlays for content-based searching\\nYear: 2005\\n\\nAbstract: A lot of recent research on content-based P2P searching for file- sharing applications has focused on exploiting semantic relations between peers to facilitate searching. To the best of our knowledge, all methods proposed to date suggest reactive ways to seize peers' semantic relations. That is, they rely on the usage of the underlying search mechanism, and infer semantic relations based on the queries placed and the corresponding replies received. In this paper we follow a different approach, proposing a proactive method to build a semantic overlay. Our method is based on an epidemic protocol that clusters peers with similar content. It is worth noting that this peer clustering is done in a completely implicit way, that is, without requiring the user to specify his preferences or to characterize the content of files he shares.\",\n \"Title: Replication for web hosting systems\\nYear: 2004\\n\\nAbstract: Replication is a well-known technique to improve the accessibility of Web sites. It generally offers reduced client latencies and increases a site's availability. However, applying replication techniques is not trivial, and various Content Delivery Networks (CDNs) have been created to facilitate replication for digital content providers. The success of these CDNs has triggered further research efforts into developing advanced Web replica hosting systems. These are systems that host the documents of a website and manage replication automatically. To identify the key issues in designing a wide-area replica hosting system, we present an architectural framework. The framework assists in characterizing different systems in a systematic manner. We categorize different research efforts and review their relative merits and demerits. As an important side-effect, this review and characterization shows that there a number of interesting research questions that have not received much attention yet, but which deserve exploration by the research community.\",\n \"Title: Practical large-scale latency estimation\\nYear: 2008\\n\\nAbstract: We present the implementation of a large-scale latency estimation system based on GNP and incorporated into the Google content delivery network. Our implementation employs standard features of contemporary Web clients, and carefully controls the overhead incurred by latency measurements using a scalable centralized scheduler. It also requires only a small number of CDN modifications, which makes it attractive for any CDN interested in large-scale latency estimation. We investigate the issue of coordinate stability over time and show that coordinates drift away from their initial values with time, so that 25% of node coordinates become inaccurate by more than 33ms after one week. However, daily re-computations make 75% of the coordinates stay within 6ms of their initial values. Furthermore, we demonstrate that using coordinates to decide on client-to-replica re-direction leads to selecting replicas closest in term of measured latency in 86% of all cases. In another 10% of all cases, clients are re-directed to replicas offering latencies that are at most two times longer than optimal. Finally, collecting a huge volume of latency data and using clustering techniques enable us to estimate latencies between globally distributed Internet hosts that have not participated in our measurements at all. The results are sufficiently promising that Google may offer a public interface to the latency estimates in the future.\",\n \"Title: A Security Architecture for Object-Based Distributed Systems\\nYear: 2002\\n\\nAbstract: Large-scale distributed systems present numerous securityproblems not present in local systems. In this paperwe present a general security architecture for a large-scaleobject-based distributed system. Its main features includeways for servers to authenticate clients, clients to authenticateservers, new secure servers to be instantiated withoutmanual intervention, and ways to restrict which client canperform which operation on which object. All of these featuresare done in a platform- and application-independentway, so the results are quite general. The basic idea behindthe scheme is to have each object owner issue cryptographicallysealed certificates to users to prove which operationsthey may request and to servers to prove which operationsthey are authorized to execute. These certificates are usedto ensure secure binding and secure method invocation. Thepaper discusses the required certificates and security protocolsfor using them.\",\n \"Title: Service-oriented data denormalization for scalable web applications\\nYear: 2008\\n\\nAbstract: Many techniques have been proposed to scale web applications. However, the data interdependencies between the database queries and transactions issued by the applications limit their efficiency. We claim that major scalability improvements can be gained by restructuring the web application data into multiple independent data services with exclusive access to their private data store. While this restructuring does not provide performance gains by itself, the implied simplification of each database workload allows a much more efficient use of classical techniques. We illustrate the data denormalization process on three benchmark applications: TPC-W, RUBiS and RUBBoS. We deploy the resulting service-oriented implementation of TPC-W across an 85-node cluster and show that restructuring its data can provide at least an order of magnitude improvement in the maximum sustainable throughput compared to master-slave database replication, while preserving strong consistency and transactional properties.\",\n \"Title: A Modeling Framework for Gossip-based Information Spread\\nYear: 2011\\n\\nAbstract: We present an analytical framework for gossip protocols based on the pair wise information exchange between interacting nodes. This framework allows for studying the impact of protocol parameters on the performance of the protocol. Previously, gossip-based information dissemination protocols have been analyzed under the assumption of perfect, lossless communication channels. We extend our framework for the analysis of networks with lossy channels. We show how the presence of message loss, coupled with specific topology configurations, impacts the expected behavior of the protocol. We validate the obtained models against simulations for two protocols.\",\n \"Title: Transparent Distributed Redirection of HTTP Requests\\nYear: 2003\\n\\nAbstract: Replication in the World-Wide Web covers a wide rangeof techniques. Often, the redirection of a client browser towardsa given replica of a Web page has to be explicit andis performed after the client's request has reached the Webserver storing the requested page. As an alternative, wepropose to perform the redirection as close to the client aspossible in a fully distributed manner. Distributed redirectionensures that we find a replica wherever it is stored andthat the closest possible replica is always found first. Byexploiting locality, we can keep latency low.\",\n \"Title: A Distributed-Object Infrastructure for Corporate Websites\\nYear: 2000\\n\\nAbstract: A corporate website is the virtual representation of a corporation or organization on the Internet. Corporate websites face numerous problems due to their large size and complexity, and the non-scalability of the underlying Web infrastructure. Current solutions to these problems generally rely on traditional scaling techniques such as caching and replication. These are usually too restrictive, however, taking a one-size-fits-all approach and applying the same solution to every document. We propose Globe as a foundation upon which to build scalable corporate websites, and introduce GlobeDoc, a website model based on Globe distributed shared objects. This paper describes GlobeDoc, highlighting the design and technical details of the infrastructure.\",\n \"Title: Exploring Design Tradeoffs Of A Distributed Algorithm For Cosmic Ray Event Detection\\nYear: 2012\\n\\nAbstract: Many sensor networks, including large particle detector arrays measuring high-energy cosmic-ray air showers, traditionally rely on centralised trigger algorithms to find spatial and temporal coincidences of individual nodes. Such schemes suffer from scalability problems, especially if the nodes communicate wirelessly or have bandwidth limitations. However, nodes which instead communicate with each other can, in principle, use a distributed algorithm to find coincident events themselves without communication with a central node. We present such an algorithm and consider various design tradeoffs involved, in the context of a potential trigger for the Auger Engineering Radio Array (AERA).\",\n \"Title: An architecture for a wide area distributed system\\nYear: 1996\\n\\nAbstract: Distributed systems provide sharing of resources and information over a computer network. A key design issue that makes these systems attractive is that all aspects related to distribution are transparent to users. Unfortunately, general-purpose wide area distributed systems that allow users to share and manage arbitrary resources in a transparent way hardly exist. In particular, they generally do not take into account the most important properties that characterize wide area systems: 1) A very large number of users and resources, 2) an inherent latency problem caused by the distance between nodes, 3) heterogeneity due to a variety of underlying operating systems and networks, and 4) involvement of multiple administrative organizations.The research described in this paper is part of the Globe Project (Globe stands for GLobal Object Based Environment). The goal of this project is the design and implementation of a wide area distributed system that provides a convenient programming abstraction and full transparency. The main contribution of this paper is the description of a new system for distributed shared objects. In contrast to other systems, the implementation of distribution, consistency, and replication of state is completely encapsulated in a distributed shared object. This allows for object-specific solutions, and provides the right mechanism for building efficient and truly scalable systems.\",\n \"Title: Autonomic Data Placement Strategies for Update-intensiveWeb applications\\nYear: 2005\\n\\nAbstract: Edge computing infrastructures have become the leading platform for hosting Web applications. One of the key challenges in these infrastructures is the replication of application data. In our earlier research, we presented GlobeDB, a middleware for edge computing infrastructures that performs autonomic replication of application data. In this paper, we study the problem of data unit placement for updateintensive Web applications in the context of GlobeDB. Our hypothesis is that there exists a continuous spectrum of placement choices between complete partitioning of sets of data units across edge servers and full replication of data units to all servers. We propose and evaluate different families of heuristics for this problem of replica placement. As we show in our experiments, a heuristic that takes into account both the individual characteristics of data units and the overall system load performs best.\",\n \"Title: Versatile anycasting with mobile IPv6.\\nYear: 2006\\n\\nAbstract: Anycasting was introduced to facilitate efficient communication between distributed Internet services and their clients, as it allows client requests to be automatically routed to nearby service instances. However, even though several any-cast implementations have been proposed, their various limitations prevent them from being widely adopted by large-scale distributed systems.This paper identifies the key limitations of existing anycast implementations, and proposes how to implement anycast such that all these limitations are addressed without harming the performance of anycast communication. Our solution relies on address-translation capabilities present in modern operating systems. These capabilities have originally been designed for communication with mobile nodes. However, we demonstrate that one can exploit them to implement versatile anycasting at low cost.\",\n \"Title: Prudent Practices for Designing Malware Experiments: Status Quo and Outlook\\nYear: 2012\\n\\nAbstract: Malware researchers rely on the observation of malicious code in execution to collect datasets for a wide array of experiments, including generation of detection models, study of longitudinal behavior, and validation of prior research. For such research to reflect prudent science, the work needs to address a number of concerns relating to the correct and representative use of the datasets, presentation of methodology in a fashion sufficiently transparent to enable reproducibility, and due consideration of the need not to harm others. In this paper we study the methodological rigor and prudence in 36 academic publications from 2006 -- 2011 that rely on malware execution. 40% of these papers appeared in the 6 highest-ranked academic security conferences. We find frequent shortcomings, including problematic assumptions regarding the use of execution-driven datasets (25% of the papers), absence of description of security precautions taken during experiments (71% of the articles), and oftentimes insufficient description of the experimental setup. Deficiencies occur in top-tier venues and elsewhere alike, highlighting a need for the community to improve its handling of malware datasets. In the hope of aiding authors, reviewers, and readers, we frame guidelines regarding transparency, realism, correctness, and safety for collecting and using malware datasets.\",\n \"Title: A robust and scalable peer-to-peer gossiping protocol\\nYear: 2003\\n\\nAbstract: The newscast model is a general approach for communication in large agent-based distributed systems. The two basic services—membership management and information dissemination—are implemented by the same epidemic-style protocol. In this paper we present the newscast model and report on experiments using a Java implementation. The experiments involve communication in a large, wide-area cluster computer. By analysis of the outcome of the experiments we demonstrate that the system indeed shows the scalability and dependability properties predicted by our previous theoretical and simulation results.\",\n \"Title: The distributed ASCI Supercomputer project\\nYear: 2000\\n\\nAbstract: The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project.\",\n \"Title: Optimal Decentralized Formation of k-Member Partnerships\\nYear: 2010\\n\\nAbstract: To keep pace with constantly changing markets, many companies are seeking strategic partnerships. In this paper, we assume that a company can electronically provide a profile of the product or service it has to offer. This profile is described in such a way that potential partners can assess the fitness of the company for eventually teaming up. We concentrate on the fully decentralized optimal formation of teams consisting of k members. This problem boils down to developing a decentralized, efficient algorithm for solving a variant of the maximal weighted k-sub graph problem. We provide a first solution, along with an assessment of its performance, thereby concentrating on the feasibility of an actual embedding in real-world scenarios consisting of thousands of companies. In particular, any solution should be highly adaptive when new or fresh information concerning potential partners comes available.\",\n \"Title: On Botnets That Use DNS for Command and Control\\nYear: 2011\\n\\nAbstract: We discovered and reverse engineered Feederbot, a botnet that uses DNS as carrier for its command and control. Using k-Means clustering and a Euclidean Distance based classifier, we correctly classified more than 14m DNS transactions of 42,143 malware samples concerning DNS-C&C usage, revealing another bot family with DNS C&C. In addition, we correctly detected DNS C&C in mixed office workstation network traffic.\",\n \"Title: Dynamically Selecting Optimal Distribution Strategies for Web Documents\\nYear: 2002\\n\\nAbstract: To improve the scalability of the Web, it is common practice to apply caching and replication techniques. Numerous strategies for placing and maintaining multiple copies of Web documents at several sites have been proposed. These approaches essentially apply a global strategy by which a single family of protocols is used to choose replication sites and keep copies mutually consistent. We propose a more flexible approach by allowing each distributed document to have its own associated strategy. We propose a method for assigning an optimal strategy to each document separately and prove that it generates a family of optimal results. Using trace-based simulations, we show that optimal assignments clearly outperform any global strategy. We have designed an architecture for supporting documents that can dynamically select their optimal strategy and evaluate its feasibility.\",\n \"Title: Unifying User-to-User Messaging Systems\\nYear: 2004\\n\\nAbstract: Unification of user-to-user messaging systems facilitates message exchange independent of time, place, protocol, and end-user device.This article describes an approach to unification that is based on introducing a middleware layer instead of employing gateways. It entails a single system that provides common services such as email, fax, and short messaging, but that can also enable novel services that current messaging systems can't support.The authors also describe how the model can be efficiently implemented on a global scale.\",\n \"Title: Globule: A Platform for Self-Replicating Web Documents\\nYear: 2001\\n\\nAbstract: Replicating Web documents at a worldwide scale can help reduce user-perceived latency and wide-area network traffic. This paper presents the design of Globule, a platform that automates all aspects of such replication: server-to-server peering negotiation, creation and destruction of replicas, selection of the most appropriate replication strategies on a per-document basis, consistency management and transparent redirection of clients to replicas. Globule is initially directed to support standard Web documents. However, it can also be applied to stream-oriented documents. To facilitate the transition from a non-replicated server to a replicated one, we designed Globule as a module for the Apache Web server. Therefore, converting Web documents should require no more than compiling a new module into Apache and editing a configuration file.\",\n \"Title: Globe: A Wide-Area Distributed System\\nYear: 1999\\n\\nAbstract: Developing large-scale wide-area applications requires an infrastructure that is presently lacking. Currently, most Internet applications have to be built on top of raw communication services, such as TCP connections. All additional services, including those for naming, replication, migration, persistence, fault tolerance, and security, have to be implemented for each application anew. Not only is this a waste of effort, it also makes interoperability between different applications difficult or even impossible. The authors present a novel, object-based framework for developing wide-area distributed applications. The framework is based on the concept of a distributed shared object, which has the characteristic feature that its state can be physically distributed across multiple machines at the same time. All implementation aspects, including communication protocols, replication strategies, and distribution and migration of state, are part of each object and are hidden behind its interface. The current performance problems of the World-Wide Web are taken as an example to illustrate the benefit of encapsulating state, operations, and implementation strategies on a per-object basis. The authors describe how distributed objects can be used to implement worldwide scalable Web documents.\",\n \"Title: GSpace: an architectural approach for self-managing extra-functional concerns\\nYear: 2008\\n\\nAbstract: Middleware-based solutions for self-managing systems provide a degree of separation between the mechanisms that govern the adaptability of a system and application functionality. Systems become in this way more flexible, dependable and robust to changes. However, it is possible to achieve another degree of separation by separating from the application logic the different extra-functional concerns (such as availability, performance, and security). This separation, known as Separation of Concerns principle, helps in generating software artifacts that are more maintainable and reusable. In this paper, we propose an architectural model for a middleware-based solution where the self-managing principle is applied to extra-functional concerns. Our middleware, based on the Shared Data Space model, is capable of dynamically adapt extra-functional concerns to the actual needs of the applications.\",\n \"Title: A method for decentralized clustering in large multi-agent systems\\nYear: 2003\\n\\nAbstract: This paper examines a method of clustering within a fully decentralized multi-agent system. Our goal is to group agents with similar objectives or data, as is done in traditional clustering. However, we add the additional constraint that agents must remain in place on a network, instead of first being collected into a centralized database. To do this we connect agents in a random network and have them search in a peer-to-peer fashion for other similar agents. We thus aim to tackle the basic clustering problem on an Internet scale and create a method by which agents themselves can be grouped, forming coalitions. In order to investigate the feasibility of a decentralized approach, this paper presents a number of simulation experiments involving agents representing two-dimensional points. A comparison between our method's clustering ability and that of the k-means clustering algorithm is presented. Generated data sets containing 2,500 to 160,000 points (agents) grouped in 25 to 1,600 clusters are examined. Results show that our decentralized agent method produces a better clustering than the centralized k-means algorithm, quickly placing 95% to 99% of points correctly. The the time required to find a clustering depends on the quality of solution required; a fairly good solution is quickly converged on, and then slowly improved. Overall, our experiments indicate that the time to find a particular quality of solution increases less than linearly with the number of agents.\",\n \"Title: Mechanisms for effective caching in the Globe location service\\nYear: 2000\\n\\nAbstract: Globe is a wide-area distributed system that supports mobile objects. To track and locate objects, we use a worldwide distributed location service, implemented as a search tree.An object registers its current position by storing its address in a nearby leaf node of the tree. This knowledge propagates up to the top of the tree, so every object can be found from the root. Remote objects can cache the location of an object. However, if the object moves, the cache entry is no longer valid.In this paper, we show how caching can be made to work effectively even in the presence of mobile objects.\",\n \"Title: Achieving Scalability in Hierarchical Location Services\\nYear: 2002\\n\\nAbstract: Services for locating mobile objects are often organized as a distributed search tree. The advantage of this approach is that the service can scale as a system grows in size and number of objects. However, a potential problem is that high-level nodes may become a bottleneck affecting the scalability of the service. A traditional solution is to also distribute the location information managed by a single node across multiple machines. We introduce a method that radically applies distribution of location information such that the load is evenly balanced across all machines that form part of the implementation of the service, while at the same time exploiting locality.\",\n \"Title: Providing data confidentiality against malicious hosts in Shared Data Spaces\\nYear: 2010\\n\\nAbstract: Coordination languages are often used to describe open-ended systems. This makes it challenging to develop tools for guaranteeing the security of the coordinated systems and the correctness of their interaction. Successful approaches to this problem ...\",\n \"Title: On leveraging social relationships for decentralized privacy-preserving group communication\\nYear: 2012\\n\\nAbstract: Millions of people use the Internet today for data exchange of sensitive information. A typical exchange usually occurs within the context of a group of users and often takes place in a centrally managed infrastructure such as Facebook. Evidence has shown that such systems are unable to properly protect the privacy of its users. Following this observation, we present a framework to support privacy-preserving group communication. Our framework is completely decentralized and leverages the social relationships between users to bootstrap a communication overlay whose robustness is improved with the addition of extra privacy-preserving links. The framework supports multiple groups in a scalable manner and defines mechanisms to handle churn in group membership. Finally, we also outline high-level protocols for a privacy-preserving micro-news application.\",\n \"Title: A Multiphased Approach for Modeling and Analysis of the BitTorrent Protocol\\nYear: 2007\\n\\nAbstract: BitTorrent is one of the most popular protocols for content distribution and accounts for more than 15% of the total Internet traffic. In this paper, we present an analytical model of the protocol. Our work differs from previous works as it models the BitTorrent protocol specifically and not as a general file-swarming protocol. In our study, we observe that to accurately model the download process of a BitTorrent client, we need to split this process into three phases. We validate our model using simulations and realworld traces. Using this model, we study the efficiency of the protocol based on various protocol-specific parameters such as the maximum number of connections and the peer set size. Furthermore, we study the relationship between changes in the system parameters and the stability of the protocol. Our model suggests that the stability of BitTorrent protocol depends heavily on the number of pieces a file is divided into and the arrival rate of clients to the network.\",\n \"Title: An Amortized Tit-For-Tat Protocol for Exchanging Bandwidth instead of Content in P2P Networks\\nYear: 2007\\n\\nAbstract: Incentives for resource sharing are crucial for the proper operation of P2P networks. The principle of the incen- tive mechanisms in current content sharing P2P networks such as BitTorrent is to have peers exchange content of mu- tual interest. As a consequence, a peer can actively par- ticipate in the system only if it shares content that is of immediate interest to other peers. In this paper we pro- pose to lift this restriction by using bandwidth rather than content as the resource upon which incentives are based. Bandwidth, in contrast to content, is independent of peer interests and so can be exchanged between any two peers. We present the design of a protocol called amortized tit- for-tat (ATFT) based on the bandwidth-exchange concept. This protocol defines mechanisms for bandwidth exchange corresponding to those in BitTorrent for content exchange, in particular for finding bandwidth borrowers that amortize the bandwidth borrowed in the past with their currently idle bandwidth. In addition to the formally proven incentives for bandwidth contributions, ATFT provides natural solu- tions to the problems of peer bootstrapping, seeding incen- tive, peer link asymmetry, and anonymity, which have previ- ously been addressed with much more complex designs. Ex- periments with a real-world dataset confirm that ATFT is efficient in enforcing bandwidth contributions and results in download performance better than provided by incentive mechanisms based on content exchange.\",\n \"Title: 2Fast: Collaborative Downloads in P2P Networks\\nYear: 2006\\n\\nAbstract: P2P systems that rely on the voluntary contribution of bandwidth by the individual peers may suffer from freeriding. To address this problem, mechanisms enforcing fairness in bandwidth sharing have been designed, usually by limiting the download bandwidth to the available upload bandwidth. As in real environments the latter is much smaller than the former, these mechanisms severely affect the download performance of most peers. In this paper we propose a system called 2Fast, which solves this problem while preserving the fairness of bandwidth sharing. In 2Fast, we form groups of peers that collaborate in downloading a file on behalf of a single group member, which can thus use its full download bandwidth. A peer in our system can use its currently idle bandwidth to help other peers in their ongoing downloads, and get in return help during its own downloads. We assess the performance of 2Fast analytically and experimentally, the latter in both real and simulated environments. We find that in realistic bandwidth limit settings, 2Fast improves the download speed by up to a factor of 3.5 in comparison to state-of-the-art P2P download protocols.\",\n \"Title: Dynamically adapting tuple replication for managing availability in a shared data space\\nYear: 2005\\n\\nAbstract: With its decoupling of processes in space and time, the shared data space model has proven to be a well-suited solution for developing distributed component-based systems. However, as in many distributed applications, functional and extra-functional aspects are still interwoven in components. In this paper, we address how shared data spaces can support separation of concerns. In particular, we present a solution that allows developers to merely specify performance and availability requirements for data tuples, while the underlying middleware evaluates various distribution and replication policies in order to select the one that meets these requirements best. Moreover, in our approach, the middleware continuously monitors the behavior of application and system components, and switches to different policies if this would lead to better results. We describe our approach, along with the design of a prototype implementation and its quantitative evaluation.\",\n \"Title: Scalable strong consistency for web applications\\nYear: 2004\\n\\nAbstract: Web application workloads are often characterized by a large number of unique read requests and a significant fraction of write requests. Hosting these applications drives the need for the next generation CDN architecture that does more than caching the results of Web applications but replicates both the application code and its underlying data. We propose the design of a system that guarantees strong consistency for Web applications with high scalability. The proposed system is based on partial replication, where data units are replicated only to servers that access them often. This reduces the consistency overhead as updates are sent to a reduced number of servers. The novelty of our system is that the proposed partial replication is performed by the system automatically by analyzing the system's access patterns periodically. We explore the design space of this system, find the key issues that need to be addressed to build it and propose solutions to solve them. We further show that the proposed algorithms offer significant performance gains compared to existing solutions for a wide range of Web access patterns.\",\n \"Title: Broker-placement in latency-aware peer-to-peer networks\\nYear: 2008\\n\\nAbstract: In large peer-to-peer (P2P) overlay networks, nodes usually share resources to support all kinds of applications. In such networks, a subset of the nodes may assume the role of broker in order to act as intermediaries for finding the shared resources. When some notion of distance between nodes such as the internode latency is defined, a brokers may be responsible for maintaining information about resources shared by a group of nodes that are close to each other, with the set of nodes assigned to a broker being determined by the broker's location. In this paper, we present a broker-placement algorithm that finds a suitable location for a new broker when some broker is overloaded in such a way that some of the nodes are reassigned from the overloaded to the new broker. With latency as a metric, an overlay network can be embedded in an Euclidean space R^d, and our algorithm amounts to an optimization problem of selecting a suitable region in R^d for broker-placement, where a region represents equivalent broker locations. Our algorithm guarantees that if suitable regions exist, one of them will be found. The worst-case complexity of the algorithm is O(n^d^+^1) with n the number of nodes that may be assigned to the new broker, which is optimal up to a linear factor in n. We further show a simple optimization that brings down the complexity of the algorithm to a linear function of n in most of the cases. The linear complexity of the broker-placement algorithm is confirmed in a series of experiments on a real dataset. In addition, the performance of our broker-placement algorithm is compared to the performance of a naive approach, and it turns out that in a system with one million servers and one hundred brokers, our broker-placement algorithm is roughly 150 times more efficient.\",\n \"Title: Decentralized group formation.\\nYear: 2014\\n\\nAbstract: Imagine a network of entities, being it replica servers aiming to minimize the probability of data loss, players of online team-based games and tournaments, or companies that look into co-branding opportunities. The objective of each entity in any of these scenarios is to find a few suitable partners to help them achieve a shared goal: replication of the data for fault tolerance, winning the game, successful marketing campaign. All information attainable by the entities is limited to the profiles of other entities that can be used to assess the pairwise fitness. How can they create teams without help of any centralized component and without going into each other’s way? We propose a decentralized algorithm that helps nodes in the network to form groups of a specific size. The protocol works by finding an approximation of a weighted k-clique matching of the underlying graph of assessments. We discuss the basic version of the protocol, and explain how dissemination via gossiping helps in improving its scalability. We evaluate its performance through extensive simulations.\",\n \"Title: From proximity sensing to spatio-temporal social graphs\\nYear: 2014\\n\\nAbstract: Understanding the social dynamics of a group of people can give new insights into social behavior. Physical proximity between individuals results from the interactions between them. Hence, measuring physical proximity is an important step towards a better understanding of social behavior. We discuss a novel approach to sense proximity from within the social dynamics. Our primary objective is to construct a spatio-temporal social graph from noisy proximity data. We address the technical and algorithmic challenges of measuring proximity reliably and accurately. Simulations and real world experiments demonstrate the feasibility and scalability of our approach. Our algorithms doubles the sensitivity of proximity detections at the cost of a slight reduction in specificity.\",\n \"Title: Scalable cooperative latency estimation\\nYear: 2004\\n\\nAbstract: This paper discusses SCoLE, a scalable system to estimate Internet latencies. SCoLE is based on GNP, which models Internet latencies in an n-dimensional Euclidean space. In contrast to GNP and other GNP-based systems, however, SCoLE does not employ any global space whose parameters must typically be negotiated by the participating hosts. Instead, it allows each host to construct its \\\"'private\\\" space and model interhost latencies in that space. The private space parameters as well as the modeling algorithm can be adjusted on a per-host basis, which improves system flexibility. More importantly, the mutual independence of private spaces results in higher SCoLE scalability, which is bound neither by the global negotiation of space parameters nor by global knowledge of any kind. We show that latency estimates performed in different private spaces are highly correlated. This allows SCoLE to be used in large-scale applications where consistent latency estimates need to be performed simultaneously by many independent hosts.\",\n \"Title: Scalable human-friendly resource names\\nYear: 2001\\n\\nAbstract: Currently, Uniform Resource Locators (URLs) are used to name and access Web-based resources. However, URLs pose a significant scalability problem because they cannot be used to refer to replicated Web pages. The authors propose a new URI scheme called Human-Friendly Names (HFNs) to solve this scalability problem. HFNs are high-level names that are easy-to-use by humans and name Web resources in a location-independent way. This article describes a scalable HFN-to-URL resolution mechanism that is based on URNs and makes use of the Domain Name System (DNS) and the Globe Location Service.\",\n \"Title: Autonomous Resource Selection for Decentralized Utility Computing\\nYear: 2009\\n\\nAbstract: Many large-scale utility computing infrastructures comprise heterogeneous hardware and software resources. This raises the need for scalable resource selection services, which identify resources that match application requirements, and can potentially be assigned to these applications. We present a fully decentralized resource selection algorithm by which resources autonomously select themselves when their attributes match a query. An application specifies what it expects from a resource by means of a conjunction of (attribute, value-range) pairs, which are matched against the attribute values of resources. We show that our solution scales in the number of resources as well as in the number of attributes, while being relatively insensitive to churn and other membership changes such as node failures.\",\n \"Title: Robust Overlays for Privacy-Preserving Data Dissemination over a Social Graph\\nYear: 2012\\n\\nAbstract: A number of recently proposed systems provide secure and privacy-preserving data dissemination by leveraging pre-existing social trust relations and effectively mapping them into communication links. However, as we show in this paper, the underlying trust graph may not be optimal as a communication overlay. It has relatively long path lengths and it can be easily partitioned in scenarios where users are unavailable for a fraction of time. Following this observation, we present a method for improving the robustness of trust-based overlays. Essentially, we start with an overlay derived from the trust graph and evolve it in a privacy-preserving fashion into one that lends itself to data dissemination. The experimental evaluation shows that our approach leads to overlays that are significantly more robust under churn, and exhibit lower path lengths than the underlying trust graph.\",\n \"Title: The Design and Evaluation of a Self-Organizing Superpeer Network\\nYear: 2010\\n\\nAbstract: Superpeer architectures exploit the heterogeneity of nodes in a peer-to-peer (P2P) network by assigning additional responsibilities to higher capacity nodes. In the design of a superpeer network for file sharing, several issues have to be addressed: how client peers are related to superpeers, how superpeers locate files, how the load is balanced among the superpeers, and how the system deals with node failures. In this paper, we introduce a self-organizing superpeer network architecture (SOSPNet) that solves these issues in a fully decentralized manner. SOSPNet maintains a superpeer network topology that reflects the semantic similarity of peers sharing content interests. Superpeers maintain semantic caches of pointers to files, which are requested by peers with similar interests. Client peers, on the other hand, dynamically select superpeers offering the best search performance. We show how this simple approach can be employed not only to optimize searching, but also to solve generally difficult problems encountered in P2P architectures such as load balancing and fault tolerance. We evaluate SOSPNet using a model of the semantic structure derived from eight-month traces of two large file-sharing communities. The obtained results indicate that SOSPNet achieves close-to-optimal file search performance, quickly adjusts to changes in the environment (node joins and leaves), survives even catastrophic node failures, and efficiently distributes the system load taking into account superpeer capacities.\",\n \"Title: Merging ultra-low duty cycle networks\\nYear: 2011\\n\\nAbstract: Energy is the scarcest resource in ad-hoc wireless networks, particularly in wireless sensor networks requiring a long lifetime. Intermittently switching the radio on and off is widely adopted as the most effective way to keep energy consumption low. This, however, prevents the very goal of communication, unless nodes switch their radios on at synchronized intervals, a rather nontrivial coordination task. In this paper we address the problem of synchronizing node radios to a single universal schedule in very large scale wireless ad-hoc networks. More specifically, we focus on how independently synchronized clusters of nodes can detect each other and merge to a common radio schedule. Our main contributions consist in identifying the fundamental subproblems that govern cluster merging, providing a detailed comparison of the respective policies and their combinations, and supporting them by extensive simulation. Energy consumption, convergence speed, and network scalability have been the driving factors in our evaluation. The proposed policies are extensively tested in networks of up to 4,096 nodes. Our work is based on the GMAC protocol, a gossip-based MAC protocol for wireless ad-hoc networks.\",\n \"Title: Decentralized Network-Level Synchronization in Mobile Ad Hoc Networks.\\nYear: 2016\\n\\nAbstract: Energy is the scarcest resource in ad hoc wireless networks, particularly in wireless sensor networks requiring a long lifetime. Intermittently switching the radio on and off is widely adopted as the most effective way to keep energy consumption low. This, however, prevents the very goal of communication, unless nodes switch their radios on at synchronized intervals—a rather nontrivial coordination task. In this article, we address the problem of synchronizing node radios to a single universal schedule in wireless mobile ad hoc networks that can potentially consist of thousands of nodes. More specifically, we are interested in operating the network with duty cycles that can be less than 1p of the total cycle time. We identify the fundamental issues that govern cluster merging and provide a detailed comparison of various policies using extensive simulations based on a variety of mobility patterns. We propose a specific scheme that allows a 4,000-node network to stay synchronized with a duty cycle of approximately 0.7p. Our work is based on an existing, experimental MAC protocol that we use for real-world applications and is validated in a real network of around 120 mobile nodes.\",\n \"Title: GDCluster: A General Decentralized Clustering Algorithm\\nYear: 2015\\n\\nAbstract: In many popular applications like peer-to-peer systems, large amounts of data are distributed among multiple sources. Analysis of this data and identifying clusters is challenging due to processing, storage, and transmission costs. In this paper, we propose GDCluster, a general fully decentralized clustering method, which is capable of clustering dynamic and distributed data sets. Nodes continuously cooperate through decentralized gossip-based communication to maintain summarized views of the data set. We customize GDCluster for execution of the partition-based and density-based clustering methods on the summarized views, and also offer enhancements to the basic algorithm. Coping with dynamic data is made possible by gradually adapting the clustering model. Our experimental evaluations show that GDCluster can discover the clusters efficiently with scalable transmission cost, and also expose its supremacy in comparison to the popular method LSP2P.\",\n \"Title: Proximity Graphs for Crowd Movement Sensors.\\nYear: 2015\\n\\nAbstract: Sensors are now common, they span over different applications, different purposes and some over large geospatial areas. Most data produced by these sensors needs to be linked to the physical location of the sensor itself. By using the location of a sensor we can construct (mathematically) proximity graphs that have the sensors as nodes. These graphs have a wide variety of applications including visualization, packet routing, and spatial data analysis.We consider a sensor network that measures detections of WiFi packets transmitted by devices, such as smartphones. One important feature of sensors is given by the range in which they can gather data. Algorithms that build proximity graphs do not take this radius into account.We present an approach to building proximity graph that takes sensor position and radius as input. Our goal is to construct a graph that contains edges between pairs of sensors that are correlated to crowd movements, reflecting paths that individuals are likely to take. Because we are considering crowd movement, it gives us the unique opportunity to construct graphs that show the connections between sensors using consecutive detections of the same device. We show that our approach is better than ones that are based on the positioning of sensors only.\",\n \"Title: Filters for Wi-Fi Generated Crowd Movement Data.\\nYear: 2015\\n\\nAbstract: Cities represent large groups of people that share a common infrastructure, common social groups and/or common interests. With the development of new technologies current cities aim to become what is known as smart cities, in which all the small details of these large constructs are controlled to better improve the quality of life of its inhabitants. One of the important gears that powers a city is given by traffic, be it vehicular or pedestrian. As such traffic is closely related to all other activities that take place inside of a city. Understanding traffic is still a difficult process as we have to be able to not only measure it in the sense of how many people are using a particular path but also in analyzing where people are going and when, while still maintaining individual privacy. And all this has to be done at a scale that would cover most if not all individuals in a city.With the high increase in smartphones adoption we can reliably assume that a large part of the population in cities are carrying with them, at all times, at least one Wi-Fi enabled device. Because Wi-Fi devices are regularly transmitting signals we can rely on these devices to detect individual's movements unobtrusively without identifying or tracking any particular individual. Special sensors that monitor Wi-Fi frequencies can be placed around a city to gather data that can later be used to identify patterns in the traffic flows.We present a set of filters that can be used to minimize the amount of data needed for processing and without negatively impacting the result or the information that can be extracted from this data. Part of the filters we present can be deployed at the sensor level, making the entire system more scalable, while a different part can be executed before data processing thus enabling real time information extraction and a broader temporal and spatial range for data analysis. Some of these filters are particular to Wi-Fi but some of them can be applied to any detection system.\",\n \"Title: Presumably Simple: Monitoring Crowds Using WiFi\\nYear: 2016\\n\\nAbstract: Crowd Monitoring is receiving much attention. An increasingly popular technique is to scan for mobile devices, notably smartphones. We take a look at scanning for such devices by recording WiFi packets. Although research on capturing crowd patterns using WiFi detections has been done, there are not many published results when it comes to tracking movements. This is not surprising when realizing that the data provided by WiFi scanners is susceptible to many seemingly erroneous and missed detections, caused by the use of randomized network addresses, overlap between scanners, high variance in WiFi detection ranges, among other sources. In this paper, we investigate various techniques for cleaning up sets of raw detections to sets that can subsequently be used for crowd analytics. To this end, we introduce two different quality metrics to measure the effects of applying the various techniques. We test our approach using a data set collected from 27 WiFi scanners spread across the downtown area of a Dutch city where at that time a 3-day multi-stage festival took place attended by some 130,000 people.\",\n \"Title: A brief introduction to distributed systems.\\nYear: 2016\\n\\nAbstract: Distributed systems are by now commonplace, yet remain an often difficult area of research. This is partly explained by the many facets of such systems and the inherent difficulty to isolate these facets from each other. In this paper we provide a brief overview of distributed systems: what they are, their general design goals, and some of the most common types.\",\n \"Title: Towards decisive garments for heat stress risk detection.\\nYear: 2016\\n\\nAbstract: One of the numerous applications of wearable computers is providing safety in occupations where heat-related injuries are prevalent. Core temperature, as a parameter that cannot be measured by on-body sensors is a variable that is specifically interesting for realizing such applications. In the context of the design of a sensor-shirt that can be used by firefighters, in this paper we study the importance of different types of sensor measurements and their placement for estimating core temperature. We propose a model for inferring the dangerous states of core temperature. Our evaluation results show that our model can to a great extent estimate hazardous situations caused by heat accumulation.\",\n \"Title: Using Performance Forecasting to Accelerate Elasticity.\\nYear: 2015\\n\\nAbstract: Cloud computing facilitates dynamic resource provisioning. The automation of resource management, known as elasticity, has been subject to much research. In this context, monitoring of a running service plays a crucial role, and adjustments are made when certain thresholds are crossed. On such occasions, it is common practice to simply add or remove resources. In this paper we investigate how we can predict the performance of a service to dynamically adjust allocated resources based on predictions. In other words, instead of “repairing” because a threshold has been crossed, we attempt to stay ahead and allocate an optimized amount of resources in advance. To do so, we need to have accurate predictive models that are based on workloads. We present our approach, based on the Universal Scalability Law, and discuss initial experiments.\",\n \"Title: Exploiting Density to Track Human Behavior in Crowded Environments.\\nYear: 2017\\n\\nAbstract: For the Internet of Things to be people-centered, things need to identify when people and their things are nearby. In this article, we present the design, implementation, and deployment of a positioning system based on mobile and fixed inexpensive proximity sensors that we use to track when individuals are close to an instrumented object or placed at certain points of interest. To overcome loss of data between mobile and fixed sensors due to crowd density, traditional approaches are extended with mobile-to-mobile proximity information. We tested our system in a museum crowded with thousands of visitors, showing that measurement accuracy increases in the presence of more individuals wearing a proximity sensor. Furthermore, we show that density information can be leveraged to study the behavior of the visitors, for example, to track the popularity of points of interest, and the flow and distribution of visitors across floors.\",\n \"Title: Spaceprint: a Mobility-based Fingerprinting Scheme for Public Spaces.\\nYear: 2017\\n\\nAbstract: In this paper, we address the problem of how automated situation-awareness can be achieved by learning real-world situations from ubiquitously generated mobility data. Without semantic input about the time and space where situations take place, this turns out to be a fundamental challenging problem. Uncertainties also introduce technical challenges when data is generated in irregular time intervals, being mixed with noise, and errors. Purely relying on temporal patterns observable in mobility data, in this paper, we propose Spaceprint, a fully automated algorithm for finding the repetitive pattern of similar situations in spaces. We evaluate this technique by showing how the latent variables describing the category, and the actual identity of a space can be discovered from the extracted situation patterns. Doing so, we use different real-world mobility datasets with data about the presence of mobile entities in a variety of spaces. We also evaluate the performance of this technique by showing its robustness against uncertainties.\",\n \"Title: Automated Lane Detection in Crowds using Proximity Graphs.\\nYear: 2017\\n\\nAbstract: Studying the behavior of crowds is vital for understanding and predicting human interactions in public areas. Research has shown that, under certain conditions, large groups of people can form collective behavior patterns: local interactions between individuals results in global movements patterns. To detect these patterns in a crowd, we assume each person is carrying an on-body device that acts a local proximity sensor, e.g., smartphone or bluetooth badge, and represent the texture of the crowd as a proximity graph. Our goal is extract information about crowds from these proximity graphs. In this work, we focus on one particular type of pattern: lane formation. We present a formal definition of a lane, proposed a simple probabilistic model that simulates lanes moving through a stationary crowd, and present an automated lane-detection method. Our preliminary results show that our method is able to detect lanes of different shapes and sizes. We see our work as an initial step towards rich pattern recognition using proximity graphs.\",\n \"Title: Inferring the Social-Connectedness of Locations from Mobility Data.\\nYear: 2017\\n\\nAbstract: An often discriminating feature of a location is its social character or how well its visitors know each other. In this paper, we address the question of how we can infer the social contentedness of a location by observing the presence of mobile entities in it. We study a large number of mobility features that can be extracted from visits to a location. We use these features for predicting the social tie strengths of the device owners present in the location at a given moment in time, and output an aggregate score of social connectedness for that location. We evaluate this method by testing it on a real-world dataset. Using a synthetically modified version of this dataset, we further evaluate its robustness against factors that normally degrade the quality of such ubiquitously collected data (e.g. noise, sampling frequency). In each case, we found that the accuracy of the proposed method highly outperforms that of a state-of-the-art baseline methodology.\",\n \"Title: A Survey of Techniques for Automatically Sensing the Behavior of a Crowd.\\nYear: 2018\\n\\nAbstract: Crowd-centric research is receiving increasingly more attention as datasets on crowd behavior are becoming readily available. We have come to a point where many of the models on pedestrian analytics introduced in the last decade, which have mostly not been validated, can now be tested using real-world datasets. In this survey, we concentrate exclusively on automatically gathering such datasets, which we refer to as sensing the behavior of pedestrians. We roughly distinguish two approaches: one that requires users to explicitly use local applications and wearables, and one that scans the presence of handheld devices such as smartphones. We come to the conclusion that despite the numerous reports in popular media, relatively few groups have been looking into practical solutions for sensing pedestrian behavior. Moreover, we find that much work is still needed, in particular when it comes to combining privacy, transparency, scalability, and ease of deployment. We report on over 90 relevant articles and discuss and compare in detail 30 reports on sensing pedestrian behavior.\",\n \"Title: Identifying Movements in Noisy Crowd Analytics Data\\nYear: 2018\\n\\nAbstract: Privacy-preserved tracking of WiFi-enabled devices such as smartphones offers a highly scalable solution for large-scale crowd movement studies. However, extracting knowledge out of pedestrian-tracking data acquired this way is not simple. This is, generally, due to the inherent inaccuracy of the measurement technique. Segmenting an individual's trajectory data into periods of stops and moves is a fundamental step in analyzing crowds' movement. Such distinctions allow us to answer advanced questions regarding visited locations or even social behavior. Algorithms previously designed for distinguishing movements from stay periods, assume datasets are gathered using GPS, which offers precise positioning. WiFi tracking, however, does not offer such precision. The location of devices can at best be reduced to a large area around the WiFi scanner. In this paper, we study a set of established algorithms for detecting periods of stops and moves from GPS-based datasets and their applicability to WiFi-based data. Consequently, we propose possible improvements to such algorithms considering the inherent characteristics of WiFi tracking data.\",\n \"Title: Identifying Stops and Moves in WiFi Tracking Data.\\nYear: 2018\\n\\nAbstract: There are multiple methods for tracking individuals, but the classical ones such as using GPS or video surveillance systems do not scale or have large costs. The need for large-scale tracking, for thousands or even millions of individuals, over large areas such as cities, requires the use of alternative techniques. WiFi tracking is a scalable solution that has gained attention recently. This method permits unobtrusive tracking of large crowds, at a reduced cost. However, extracting knowledge from the data gathered through WiFi tracking is not simple, due to the low positional accuracy and the dependence on signals generated by the tracked device, which are irregular and sparse. To facilitate further data analysis, we can partition individual trajectories into periods of stops and moves. This abstraction level is fundamental, and it opens the way for answering complex questions about visited locations or even social behavior. Determining stops and movements has been previously addressed for tracking data gathered using GPS. GPS trajectories have higher positional accuracy at a fixed, higher frequency as compared to trajectories obtained through WiFi. However, even with the increase in accuracy, the problem, of separating traces in periods of stops and movements, remains similar to the one we encountered for WiFi tracking. In this paper, we study three algorithms for determining stops and movements for GPS-based datasets and explore their applicability to WiFi-based data. We propose possible improvements to the best-performing algorithm considering the specifics of WiFi tracking data.\",\n \"Title: On the Run-Time Dynamics of a Peer-to-Peer Evolutionary Algorithm\\nYear: 2008\\n\\nAbstract: In this paper we propose an improvement on a fully distributed Peer-to-Peer (P2P) Evolutionary Algorithm (EA) based on autonomous selection. Autonomous selection means that individuals decide on their own state of reproduction and survival without any central control, using instead estimations about the global population state for decision making. The population size varies at run-time as a consequence of such a decentralized reproduction and death of individuals. In order to keep it stable, we propose a self-adjusting mechanism which has been shown successful in three different search landscapes. Key are the estimations about fitness and size of the population as provided by a gossiping algorithm. Such an algorithm requires several rounds to collect the information while the individuals have to wait for synchronization. As an improvement, we propose a completely asynchronous EA which does not need waiting times. The results show that our approach outperforms quantitatively the execution time of the synchronous version.\",\n \"Title: k-Anonymous Crowd Flow Analytics\\nYear: 2020\\n\\nAbstract: Measuring pedestrian dynamics using the signals sent from smartphones has become popular. Notably, Wi-Fi-based systems are currently widely deployed. However, many such systems have also become subject to serious debate due to privacy infringement. For some time, secure hashing of a smartphone's unique MAC address was considered to be sufficient, yet this method has been overruled by Europe's General Data Protection Regulation which states that an individual should not be identifiable from any dataset without explicit prior consent. In this paper, we propose a novel anonymization technique that essentially anonymizes detected smartphones immediately at the sensor before any data on such a detection is stored for further analysis. Our solution borrows from the notion of k-anonymity, while avoiding its well-known drawbacks that lead to de-anonymization. Moreover, while ensuring what we coin detection k-anonymity, we also ensure high accuracy of counting measures when dealing with realistic pedestrian flows within crowds. We evaluate our solution both in a simulated environment and in a realistic environment reproducing real-life settings.\",\n \"Title: DEEPCASE: Semi-Supervised Contextual Analysis of Security Events\\nYear: 2022\\n\\nAbstract: Security monitoring systems detect potentially malicious activities in IT infrastructures, by either looking for known signatures or for anomalous behaviors. Security operators investigate these events to determine whether they pose a threat to their organization. In many cases, a single event may be insufficient to determine whether certain activity is indeed malicious. Therefore, a security operator frequently needs to correlate multiple events to identify if they pose a real threat. Unfortunately, the vast number of events that need to be correlated often overload security operators, forcing them to ignore some events and, thereby, potentially miss attacks. This work studies how to automatically correlate security events and, thus, automate parts of the security operator workload. We design and evaluate DEEPCASE, a system that leverages the context around events to determine which events require further inspection. This approach reduces the number of events that need to be inspected. In addition, the context provides valuable insights into why certain events are classified as malicious. We show that our approach automatically filters 86.72% of the events and reduces the manual workload of security operators by 90.53%, while underestimating the risk of potential threats in less than 0.001% of cases.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":103,"string":"103"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":69,"string":"69"}}},{"rowIdx":70,"cells":{"question_id":{"kind":"string","value":"Joaquim A Jorge"},"question":{"kind":"string","value":"Generate an abstract for the title \"Contact Activity Visualization for Seniors\" using the following items: 1. Seniors \n2. PAELife \n3. Isolation \n4. Prototypes \n5. Final Prototype"},"answer":{"kind":"string","value":"Over the years, people raise their children and watch them as they make their adult lives away from home. Because of that, seniors lose contact and intimacy with their loved ones, as physical presence isn't as possible as desirable. Also, because of physical impairments that may arrive as years pass by, seniors may experience difficulties in communicating and interacting. Thus, a research project called PAELife (Personal Assistant for the Elderly Life) was created with the aim of fighting isolation and exclusion. Our personal contribution to this project is displaying the most active contacts in a visual, powerful way so that they notice which friends are contacting them more and which ones don't contact in a long time. To achieve that, we built a set of prototypes that display contacts' activity from different sources (email, social networks, etc.) and performed two user tests, in order to identify the best alternatives and understand if the senior citizens can correctly perceive the contacts' activity. The tests' feedback allowed us to know what prototypes to choose and the ones to discard. After analyzing the results we implemented a final functional prototype that matched all the requirements collected from the users."},"correct_answer":{"kind":"string","value":"Over the years, people raise their children and watch them as they make their adult lives away from home. Because of that, seniors lose contact and intimacy with their loved ones, as physical presence isn't as possible as desirable. Also, because of physical impairments that may arrive as years pass by, seniors may experience difficulties in communicating and interacting. Thus, a research project called PAELife (Personal Assistant for the Elderly Life) was created with the aim of fighting isolation and exclusion. Our personal contribution to this project is displaying the most active contacts in a visual, powerful way so that they notice which friends are contacting them more and which ones don't contact in a long time. To achieve that, we built a set of prototypes that display contacts' activity from different sources (email, social networks, etc.) and performed two user tests, in order to identify the best alternatives and understand if the senior citizens can correctly perceive the contacts' activity. The tests' feedback allowed us to know what prototypes to choose and the ones to discard. After analyzing the results we implemented a final functional prototype that matched all the requirements collected from the users."},"documents":{"kind":"list like","value":["Title: Foot-turistic multimedia: designing interactive multimedia installations for shoe shops.\nYear: 2012\n\nAbstract: The amount of money spent in a store is positively correlated with the amount of time spent inside. We argue this is an opportunity for multimedia installations that can entertain shoppers and promote interaction with the shop's products. This was the main principle behind our design idea for two interactive installations specifically conceived for shoe shops. We present two applications of interactive multimedia to shoe shopping: an interactive semantic mirror and an interactive window logo. We also describe the results of ethnographic studies, before and after the design process. Our contribution is two-fold: (i) we develop and apply a new multimedia architecture that combines RFID in-store technology with high-end motion detection algorithms, and (ii) we describe one of the first few studies about multimedia installations for improving the shoe shopping experience, in what we call \"foot-turistic\" interactions.","Title: A narrative-based alternative to tagging\nYear: 2010\n\nAbstract: The enormous dissemination of multimedia information over the past few years has led to mechanisms to support its organization, cataloging and search through descriptions or keywords. A popular way of associating such descriptions to content is tagging as can be found in popular sites such as Flickr (for images) or Delicious (bookmarks). This method allows users to associate tags to media, richly describing its content and may help in its retrieval at a later time. However, the process is mostly unstructured, leading to several problems. Nothing guarantees that the tags used are the most appropriate or the same tags are used in similar situations, making retrieval difficult.. Our approach relies on narrative-based interfaces which use stories as an organizing principle for tagging media. Given that humans have used stories to communicate since the dawn of time, narrative is a natural form of interaction. By inter-relating bits of information into a coherent whole, stories convey data in a rich, structured way. A study carried out with 40 users over a period of three months shows that users convey almost six times more information when using narratives to describe their media than what is typical of traditional methods. Furthermore, our pilot study saw narratives increasing tag reuse to 94%. Finally, other problems found in tagging such as synonyms and polysemy were notably absent from story-generated tags","Title: Towards accessible touch interfaces\nYear: 2010\n\nAbstract: Touch screen mobile devices bear the promise of endless leisure, communication, and productivity opportunities to motor-impaired people. Indeed, users with residual capacities in their upper extremities could benefit immensely from a device with no demands regarding strength. However, the precision required to effectively select a target without physical cues creates problems to people with limited motor abilities. Our goal is to thoroughly study mobile touch screen interfaces, their characteristics and parameterizations, thus providing the tools for informed interface design for motor-impaired users. We present an evaluation performed with 15 tetraplegic people that allowed us to understand the factors limiting user performance within a comprehensive set of interaction techniques (Tapping, Crossing, Exiting and Directional Gesturing) and parameterizations (Position, Size and Direction). Our results show that for each technique, accuracy and precision vary across different areas of the screen and directions, in a way that is directly dependent on target size. Overall, Tapping was both the preferred technique and among the most effective. This proves that it is possible to design inclusive unified interfaces for motor-impaired and able-bodied users once the correct parameterization or adaptability is assured.","Title: Towards content-based retrieval of technical drawings through high-dimensional indexing\nYear: 2003\n\nAbstract: This paper presents a new approach to classify, index and retrieve technical drawings by content. Our work uses spatial relationships, visual elements and high-dimensional indexing mechanisms to retrieve complex drawings from CAD databases. This contrasts with conventional approaches which use mostly textual metadata for the same purpose.","Title: A real-time low-cost marker-based multiple camera tracking solution for virtual reality applications\nYear: 2010\n\nAbstract: One of the reasons of how virtual reality applications penetrate industrial production chains slowly is because of significant\n investment costs to purchase adequate supporting hardware. As a consequence such applications are only available to major\n companies and fail to benefit the production processes of small and medium enterprises. In this article, we introduce PTrack,\n a real-time, low-cost, marker-based multiple camera tracking solution for virtual reality providing the accuracy and scalability\n usually found in much more expensive tracking systems. PTrack is composed of single camera tracking PTrack Units. Each unit\n is connected to a video camera equipped with infrared strobes and features a novel iterative geometric pose estimation algorithm\n which does marker-based single camera tracking and is therefore completely autonomous. Multiple PTrack units successively\n extend the tracking range of the system. For a smooth transition of tracked labels from one camera to another, camera range\n areas must overlap to form a contiguous tracking space. A PTrack Sensor Fusion Module then computes the pose of a certain\n label within tracking space and forwards it to interested applications. A universal test setup for optical tracking systems\n has been built allowing to measure translational and rotational accuracy of PTrack as well as of competing systems.","Title: Pen-And-Ink For Blobtree Implicit Models\nYear: 2005\n\nAbstract: New techniques are presented for rendering complex hierarchical skeletal implicit models in several pen-and-ink styles. A particle system is employed to find interesting areas on the surface and perform stroke stylization guided by local shape features. Interesting areas include silhouette strokes and lines following local shape features, such as those caused by CSG junctions. Hidden line removal is performed either by applying a surfel technique for rapid prototyping or more accurately, by using ray tracing. Examples drawn from simple to complex models illustrate the capabilities of our system.","Title: Evaluating stories in narrative-based interfaces\nYear: 2006\n\nAbstract: Traditional ways to help users organize and retrieve their documents don't scale well, nor do they properly handle non-textual documents. This paper evaluates narrative-based interfaces as a natural and effective alternative for document retrieval. We have identified what shape document-describing stories take, and what contents to expect. This led to an interface that is able to capture stories, and a knowledge-based infrastructure to understand them. A prototype of the interface was used to validate narrative-based interfaces, with emphasis on story accuracy. To this end, we collected thirty stories whose contents were then compared to the documents they portrayed. Results allow us to conclude that, for the most part, such stories are trustworthy enough to allow humans to retrieve documents reliably (81%-91% of all information is correct). We also confirmed that stories told to a computer are similar to those told to human interviewers.","Title: Realfind: managing personal items in the physical world\nYear: 2008\n\nAbstract: While in recent years some effort has been put into helping users manage their personal information in their computers, little has been done to provide meaningful ways to organize and retrieve a user's personal physical objects. Nowadays, technologies such as RFID tags can help bridge the gap between the real and electronic worlds. We propose that a tool that keeps track of the users' objects and seamlessly inter-relates information about them with other relevant autobiographical and contextual data, about the users and their activities, can help manage and retrieve both physical and electronic items in meaningful ways. We describe a prototype tool, RealFind that allows this to take place in a synergistic and effective way. Objects can be searched for based on their properties, but also by relating them to a wide range of contextual information stored on their computers.","Title: Indexing High-Dimensional Data for Content-Based Retrieval in Large Databases\nYear: 2003\n\nAbstract: Many indexing approaches for high-dimensional data points have evolved into very complex and hard to code algorithms. Sometimes this complexity is not matched by increase in performance. Motivated by these ideas, we take a step back and look at simpler approaches to indexing multimedia data. In this paper we propose a simple, (not simplistic) yet efficient indexing structure for high-dimensional data Points of variable dimension, using dimension reduction. Our approach maps multidimensional points to a 1D line by computing their Euclidean Norm and use a B/sup +/-Tree to store data points. We exploit B/sup +/-Tree efficient sequential search to develop simple, yet performant methods to implement point, range and nearest-neighbor queries. To evaluate our technique we conducted a set of experiments, using both synthetic and real data. We analyze creation, insertion and query times as a function of data set size and dimension. Results so far show that our simple scheme outperforms current approaches, such as the Pyramid Technique, the A-Tree and the SR-Tree, for many data distributions. Moreover, our approach seems to scale better both with growing dimensionality and data set size, while exhibiting low insertion and search times.","Title: Sketch-based retrieval of ClipArt drawings\nYear: 2004\n\nAbstract: These days there are a lot of vector drawings available for people to integrate into documents. These come in a variety of formats, such as Corel, Postscript, CGM, WMF and recently SVG. Typically, such ClipArt drawings tend to be archieved and accessed by categories (e.g. food, shapes, transportation, etc.). However, to find a drawing among hundreds of thousands is not an easy task. While text-driven attempts at classifying image data have been recently supplemented with query-by-image content, these have been developed for bitmap-type data and cannot handle vectorial information. In this paper we present an approach to allow indexing and retrieving vector drawings by content from large datasets. Our prototype can already handle databases with thousands of drawings using commodity hardware. Furthermore, preliminary usability assessments show promising results and suggest good acceptance of sketching as a query mechanism by users.","Title: Sketch-based modeling with few strokes\nYear: 2005\n\nAbstract: We present a novel sketch-based system for the interactive modeling of a variety of free-form 3D objects using just a few strokes. Our technique is inspired by the traditional illustration strategy for depicting 3D forms where the basic geometric forms of the subjects are identified, sketched and progressively refined using few key strokes. We introduce two parametric surfaces, rotational and cross sectional blending, that are inspired by this illustration technique. We also describe orthogonal deformation and cross sectional oversketching as editing tools to complement our modeling techniques. Examples with models ranging from cartoon style to botanical illustration demonstrate the capabilities of our system.","Title: In search of personal information: narrative-based interfaces\nYear: 2008\n\nAbstract: Most computer users find organizing large amounts of personal information problematic. Often, hierarchies are the sole means to do it. However, users can remember a broader range of autobiographic contextual data about their personal items. Unfortunately, it can seldom be used to manage and retrieve them. Even when this is possible, it is often done by asking users to fill in values for arbitrary properties in dialog boxes or wizards. We propose that narrative-based interfaces can be a natural and effective way to help users recall relevant autobiographic data about their personal items and convey it to the computer. Using Quill, a narrative-based personal document retrieval interface, as a case-study, we show how such an interface can be designed. We demonstrate the approach's validity based on a set of user studies, discussing how the problems raised by the evaluation of such an interface were overcome.","Title: Suggestive Contours Over Point-Set Implicits\nYear: 2008\n\nAbstract: This paper presents a system that combines large point-set implicit surfaces with fast line-based rendering. We devised a new process for extracting suggestive contours quickly by using particles scattered throughout the surface to identify areas of interest, followed by clustering and line-fitting. Furthermore, we improve on state-of-the-art methods for extracting silhouettes and feature-lines by harness-ing the descriptive power of the surface representation. This provides heuristics for fast determination of curvature and allows for the local regeneration of shape-depicting line elements after editing operations. While visual examples illustrate the high quality of the drawings obtained with our application, as well as the high detail it can provide for more complex models, run-times show comparatively higher performance over similar approaches for the same number of points.","Title: Telling Stories with Dialogue Boxes to Retrieve Documents\nYear: 2004\n\nAbstract: Nowadays, it is common for users to handle large numbers of documents. Organizing and retrieving those documents is extremely difficult using the tools commonly provided for those tasks. The use of document-describing narratives constitutes an alternate, easier way of allowing the users to do so. Narratives can help them remember important information about documents and are a natural way to convey that information to computers. In order to develop this approach, it is necessary to understand what shape do document-describing stories have. To this end we interviewed 20 users and collected 60 stories about documents. Analyzing these stories yielded a thorough characterization of their contents and structure and to extract guidelines on how to deal with them. We then validated those results by creating and evaluating two lowFidelity prototypes for possible story-capturing interfaces. We found that stories told to computers can be very similar to those told to humans, if the interface is properly designed. These results seem to suggest that structured text entry is a promising design for this interface.","Title: CGEMS: Computer Graphics Educational Materials Server\nYear: 2003\n\nAbstract: Computer graphics has evolved considerably over the past few decades. As computer science, digital arts, and other areas of study that use computer graphics continue to evolve and gain new substance, educators have come to master new content and achieve deeper understandings of computers and imagery. As the core field becomes more mature, educators in all computer graphics disciplines have a greater need for high-quality curricular resources. Offering excellent educational materials is an important service to the community of educators. Such support will empower both young and seasoned educators alike to benefit from and contribute to the work of others. In this way, we can achieve a higher standard of teaching worldwide.The purpose of our work is to provide tools to foster such a community of computer graphics educators. We will present a system that will act as the means for their work to be appraised, assessed and made available to others through an online server for refereed educational content in computer graphics.In this paper we describe the basis for and highlight some of the starting requirements of CGEMS, the online Computer Graphics Educational Materials Server. This is organized around a web-based groupware application that supports the submission, review, acquisition, and archiving of curricular resources.","Title: Content-Based Retrieval Of Technical Drawings\nYear: 2005\n\nAbstract: This paper presents a new approach to classify, index and retrieve technical drawings by content. Our work uses spatial relationships, shape geometry and high-dimensional indexing mechanisms to retrieve complex drawings from CAD databases. This contrasts with conventional approaches which use mostly textual metadata. Creative designers and draftspeople often re-use data from previous projects, publications and libraries of ready-to-use components. Usually, retrieving these drawings is a slow, complex and error-prone endeavour. Unfortunately, the widespread use of CAD systems, while making it easier to create drawings, exacerbates this problem, insofar as the number of projects grows enormously, without providing adequate searching mechanisms to support retrieving these documents. We describe an approach that supports automatic indexation of technical drawing databases through drawing simplification, feature extraction and efficient algorithms to index large amounts of data. We describe in detail our classification process and present results from usability tests on our prototype.","Title: IMMIView: a multi-user solution for design review in real-time\nYear: 2010\n\nAbstract: IMMIView is an interactive system that relies on multiple modalities and multi-user interaction to support collaborative design\n review. It was designed to offer natural interaction in visualization setups such as large-scale displays, head mounted displays\n or TabletPC computers. To support architectural design, our system provides content creation and manipulation, 3D scene navigation\n and annotations. Users can interact with the system using laser pointers, speech commands, body gestures and mobile devices.\n In this paper, we describe how we design a system to answer architectural user requirements. In particular, our system takes\n advantage of multiple modalities to provide a natural interaction for design review. We also propose a new graphical user\n interface adapted to architectural user tasks, such as navigation or annotations. The interface relies on a novel stroke-based\n interaction supported by simple laser pointers as input devices for large-scale displays. Furthermore, input devices such\n as speech and body tracking allow IMMIView to support multiple users. Moreover, they allow each user to select different modalities\n according to their preference and modality adequacy for the user task. We present a multi-modal fusion system developed to\n support multi-modal commands on a collaborative, co-located, environment, i.e. with two or more users interacting at the same\n time, on the same system. The multi-modal fusion system listens to inputs from all the IMMIView modules in order to model\n user actions and issue commands. The multiple modalities are fused based on a simple rule-based sub-module developed in IMMIView\n and presented in this paper. User evaluation performed over IMMIView is presented. The results show that users feel comfortable\n with the system and suggest that users prefer the multi-modal approach to more conventional interactions, such as mouse and\n menus, for the architectural tasks presented.","Title: Towards Calligraphic Interfaces: Sketching 3D Scenes with Gestures and Context Icons\nYear: 2000\n\nAbstract: GIDeS (Gesture-based Intuitive Design System) is a gesture-based modeling system that addresses theknown ergonomic shortcomings of present-day CAD systems for conceptual shape design. GIDeS uses atablet and stylus combination to combine the intuitive appeal of gesture-based interfaces with contextbasedicons. GIDeS draws on previous modeling work, using contextual information and feedback to freeusers from remembering detailed modeling gestures, allowing them to concentrate on drawing,...","Title: Quill: a narrative-based interface for personal document retrieval\nYear: 2006\n\nAbstract: The ways to manage and retrieve documents have changed little in recent years. Browsing is increasingly unpractical and search still is fairly simple, relying mostly on keywords. The wide range of autobiographic information that users remember about their documents cannot be used. We present a new interaction paradigm, narrative-based interfaces, especially well suited for document retrieval. Stories make remembering information easier since it appears contextualized in a coherent whole. We describe the Quill system, a narrative-based query-formulation interface for personal document retrieval, explaining the user studies and results that led to its design in a sound and effective way. Its evaluation confirms that stories can be told naturally, containing the desired information about documents.","Title: Online parsing of visual languages using adjacency grammars\nYear: 1995\n\nAbstract: Visual computing environments continue to grow in importance, yet fast, general parsing algorithms for visual languages remain elusive. In this paper, we present an incremental parsing algorithm for a broad class of visual languages which do not contain overlapping elements. Our algorithm is based on the concept of adjacency grammars, where adjacencies are defined so as to encompass both spatial and logical constraints. Our approach combines bottom-up and top-down methods to support incremental parsing of visual input, allowing for measurably efficient online parsing of diagram-like visual languages, with observed linear run-times for large visual sentences.","Title: Combining bimanual manipulation and pen-based input for 3D modelling\nYear: 2011\n\nAbstract: Multitouch enabled surfaces can bring advantages to modelling scenarios, in particular if bimanual and pen input can be combined. In this work, we assess the suitability of multitouch interfaces to 3D sketching tasks. We developed a multitouch enabled version of ShapeShop, whereby bimanual gestures allow users to explore the canvas through camera operations while using a pen to sketch. This provides a comfortable setting familiar to most users. Our contribution focuses on comparing the combined approach (bimanual and pen) to the pen-only interface for similar tasks. We conducted the evaluation helped by ten sketching experts who exercised both techniques. Results show that our approach both simplifies workflow and lowers task times, when compared to the pen-only interface, which is what most current sketching applications provide.","Title: Generic shape classification for retrieval\nYear: 2005\n\nAbstract: We present a shape classification technique for structural content–based retrieval of two-dimensional vector drawings. Our method has two distinguishing features. For one, it relies on explicit hierarchical descriptions of drawing structure by means of spatial relationships and shape characterization. However, unlike other approaches which attempt rigid shape classification, our method relies on estimating the likeness of a given shape to a restricted set of simple forms. It yields for a given shape, a feature vector describing its geometric properties, which is invariant to scale, rotation and translation. This provides the advantage of being able to characterize arbitrary two–dimensional shapes with few restrictions. Moreover, our technique seemingly works well when compared to established methods for two dimensional shapes.","Title: Agrafo: a visual interface for grouping and browsing digital photos\nYear: 2008\n\nAbstract: With the growing popularity of digital cameras, the organization, browsing, management and grouping of photos become a problem of every photograph (professional or amateur), because their collections easily achieve the order of thousands. Here, we present a system to automate these processes, which relies on photo information, such as, semantic features (extracted from content), meta-information and low level.","Title: Mnemonical Body Shortcuts for Interacting with Mobile Devices\nYear: 2007\n\nAbstract: Mobile devices’ user interfaces have some similarities with the traditional interfaces offered by desktop computers, which\n are highly problematic when used in mobile contexts. Gesture recognition in mobile interaction appears as an important area\n to provide suitable on-the-move usability. We present a body space based approach to improve mobile device interaction and\n on the move performance. The human body is presented as a rich repository of meaningful relations which are always available\n to interact with. Body-based gestures allow the user to naturally interact with mobile devices with no movement limitations.\n Preliminary studies using RFID technology were performed, validating the mnemonical body shortcuts concept as a new mobile\n interaction mechanism. Finally, inertial sensing prototypes were developed and evaluated, proving to be suitable for mobile\n interaction and efficient, accomplishing a good recognition rate.","Title: Mockup Builder: 3D modeling on and above the surface.\nYear: 2013\n\nAbstract: We present Mockup Builder, a semi-immersive environment for conceptual design which allows virtual mockups to be created using gestures. Our goal is to provide familiar ways for people to conceive, create and manipulate three-dimensional shapes. To this end, we developed on-and-above-the-surface interaction techniques based on asymmetric bimanual interaction for creating and editing 3D models in a stereoscopic environment. Our approach combines both hand and finger tracking in the space on and above a multi-touch surface. This combination brings forth an alternative design environment where users can seamlessly switch between interacting on the surface or above it to leverage the benefit of both interaction spaces. A formal user evaluation conducted with experienced users shows very promising avenues for further work towards providing an alternative to current user interfaces for modeling.","Title: Modeling plant structures using concept sketches\nYear: 2006\n\nAbstract: Creating 3D plant models is often a hard and laborious task. To make it easier and more natural, we propose a sketch-based interface for modeling single-compound plant structures with phyllotactic arrangements. Our approach is based on the traditional illustration technique of concept sketching. The user sketches the key construction lines for the main plant body and lateral organs. Our system then automatically constructs the 3D plant arrangement in phyllotactic patterns rendered as pen-and-ink line drawings. The user is then able to edit the model by oversketching the construction lines, adjusting density of lateral organs, and specifying different phyllotactic patterns. We demonstrate the capabilities of our system for a variety of plant models.","Title: NavTap: a long term study with excluded blind users\nYear: 2009\n\nAbstract: NavTap is a navigational method that enables blind users to input text in a mobile device by reducing the associated cognitive load. In this paper, we present studies that go beyond a laboratorial setting, exploring the methods' effectiveness and learnability as well as its influence on the users' daily lives. Eight blind users participated in designing the prototype (3 weeks) while five took part in the studies along 16 more weeks. Results gathered in controlled weekly sessions and real life usage logs enabled us to better understand NavTap's advantages and limitations. The method revealed itself both as easy to learn and improve. Indeed, users were able to better control their mobile devices to send SMS and use other tasks that require text input such as managing a phonebook, from day one, in real-life settings. While individual user profiles play an important role in determining their evolution, even less capable users (with age-induced impairments or cognitive difficulties), were able to perform the assigned tasks (sms, directory) both in the laboratory and in everyday use, showing continuous improvement to their skills. According to interviews, none were able to input text before. Nav-Tap dramatically changed their relation with mobile devices and noticeably improved their social interaction capabilities.","Title: A comparison of ray pointing techniques for very large displays\nYear: 2010\n\nAbstract: Ray-pointing techniques are often advocated as a way for people to interact with very large displays from several meters away. We are interested in two factors that can affect ray pointing: the particular technique's control type, and parallax. Consequently, we tested four ray pointing variants on a wall display that covers a large part of the user's field of view. Tasks included horizontal and vertical targeting, and tracing. Our results show that (a) techniques based on 'rotational control' perform better for targeting tasks, and (b) techniques with low parallax are best for tracing tasks. We also show that a Fitts's law analysis based on angles (as opposed to linear distances) better approximates people's ray pointing performance.","Title: Non-photorealistic rendering in context: an observational study\nYear: 2006\n\nAbstract: Pen-and-ink line drawing techniques are frequently used to depict form, tone, and texture in artistic, technical, and scientific illustration. In non-photorealistic rendering (NPR), considerable progress has been made towards reproducing traditional pen-and-ink techniques for rendering 3D objects. However, formal evaluation and validation of these NPR images remain an important open research problem. In this paper we present an observational study with three groups of users to examine their understanding and assessment of hand-drawn pen-and-ink illustrations of objects in comparison with NPR renditions of the same 3D objects. The results show that people perceive differences between those two types of illustration but that those that look computer-generated are still highly valued as scientific illustrations.","Title: Retrieving Vector Graphics Using Sketches\nYear: 2004\n\nAbstract: In this paper we present an approach to allow indexing and retrieving vector graphics by content, using topological and geometric information automatically extracted from figures. The method described retrieves WMF ClipArt files as an instance of the general problem of searching vector drawings. Our prototype can already handle databases with thousands of drawings using commodity hardware. Our scheme uses pattern recognition to identify shapes ensuring good precision vs recall trade-offs, when compared to other approaches. Preliminary usability assessments show promising results and suggest good acceptance of sketching as a query mechanism by users.","Title: Adaptive tools for the elderly: new devices to cope with age-induced cognitive disabilities\nYear: 2001\n\nAbstract: We look at the issues and methodologies needed to develop, deploy, and evaluate situation-aware mobile computing devices that adapt to the needs of elder users based on observed or predicted user behavior and needs. This paper discusses how pervasive computing can help the aging population live independently for as long as possible. We believe that successfully applying technology to this problem will require careful studies of how the target population actually lives and what their actual needs are. We propose a combination of traditional laboratory studies and surveys, as well as the use of instrumented spaces and personal monitoring devices to measure how people behave, normally and while using proposed assistive devices. A key requirement is the development of ways to simultaneously monitor signals from the body, activities, and social interactions to provide a more complete view of individuals and their lives. Some of the core research issues are machine learning to design devices learn from and adapt to user behavior, user-computer interaction to build devices and systems that support users in their tasks, mobile computing to support user and device mobility, mobility and data management to represent, access, update, and protect information, sensing devices that monitor human activity and finally rapid prototyping of services in a sensor-rich environment, in a scalable and secure manner.","Title: Motivation To E-Learn Within Organizational Settings: An Exploratory Factor Structuret\nYear: 2006\n\nAbstract: E-learning is expected to support organizations and individuals so they can become more adaptable and competitive. However, in order for organizations to realize the full potential of this technology, they should create and sustain the right context to foster learning in articulation with business objectives. This requires active participation and engagement of workers. This work explores a variable called motivation-to-e-learn, a key component of this process. Our goal is to identify what motivation-related variables are critical for users engagements in the process. To this end, we explored the importance of a set of motivation-to-e-learn variables for a group of participants at our university. From this activity, an exploratory four-factor structure emerged that explains 67% of motivation to e-learn variance. We discuss our results, together with their implications for designing technology-supported learning experiences, lessons learned, and future work. Our contribution is a step toward integrating business processes, learners, and e-learning systems into an effective and harmonious whole.","Title: Thesaurus-based 3D Object Retrieval with Part-in-Whole Matching\nYear: 2010\n\nAbstract: Research in content-based 3D retrieval has already started, and several approaches have been proposed which use in different manner a similarity assessment to match the shape of the query against the shape of the objects in the database. However, the success of these solutions are far from the success obtained by their textual counterparts.A major drawback of most existing 3D retrieval solutions is their inability to support partial queries, that is, a query which does not need to be formulated by specifying a whole query shape, but just a part of it, for example a detail of its overall shape, just like documents are retrieved by specifying words and not whole texts. Recently, researchers have focused their investigation on 3D retrieval which is solved by partial shape matching. However, at the extent of our knowledge, there is still no 3D search engine that provides an indexing of the 3D models based on all the interesting subparts of the models.In this paper we present a novel approach to 3D shape retrieval that uses a collection-aware shape decomposition combined with a shape thesaurus and inverted indexes to describe and retrieve 3D models using part-in-whole matching. The proposed method clusters similar segments obtained trough a multilevel decomposition of models, constructing from such partition the shape thesaurus. Then, to retrieve a model containing a sub-part similar to a given query, instead of looking on a large set of subparts or executing partial matching between the query and all models in the collection, we just perform a fast global matching between the query and the few entries in the thesaurus. With this technique we overcame the time complexity problems associated with partial queries in large collections.","Title: Representing and Parsing Sketched Symbols Using Adjacency Grammars and a Grid-Directed Parser\nYear: 2007\n\nAbstract: While much work has been done in Structural and Syntactical Pattern Recognition applied to drawings, most approaches are non-interactive. However, the recent emergence of viable pen-computers makes it desirable to handle pen-input such as sketches and drawings interactively. This paper presents a syntax-directed approach to parse sketches based on Relational Adjacency Grammars, which describe spatial and topological relations among parts of a sketch. Our approach uses a 2D grid to avoid re-scanning all the previous input whenever new strokes entered into the system, thus speeding up parsing considerably. To evaluate the performance of our approach we have tested the system using non-trivial inputs analyzed with two different grammars, one to design user interfaces and the other to describe floor-plans. The results clearly show the effectiveness of our approach and demonstrate good scalability to larger drawings.","Title: The continuous interaction space: interaction techniques unifying touch and gesture on and above a digital surface\nYear: 2011\n\nAbstract: The rising popularity of digital table surfaces has spawned considerable interest in new interaction techniques. Most interactions fall into one of two modalities: 1) direct touch and multi-touch (by hand and by tangibles) directly on the surface, and 2) hand gestures above the surface. The limitation is that these two modalities ignore the rich interaction space between them. To move beyond this limitation, we first contribute a unification of these discrete interaction modalities called the continuous interaction space. The idea is that many interaction techniques can be developed that go beyond these two modalities, where they can leverage the space between them. That is, we believe that the underlying system should treat the space on and above the surface as a continuum, where a person can use touch, gestures, and tangibles anywhere in the space and naturally move between them. Our second contribution illustrates this, where we introduce a variety of interaction categories that exploit the space between these modalities. For example, with our Extended Continuous Gestures category, a person can start an interaction with a direct touch and drag, then naturally lift off the surface and continue their drag with a hand gesture over the surface. For each interaction category, we implement an example (or use prior work) that illustrates how that technique can be applied. In summary, our primary contribution is to broaden the design space of interaction techniques for digital surfaces, where we populate the continuous interaction space both with concepts and examples that emerge from considering this space as a continuum.","Title: PC Clusters for Virtual Reality\nYear: 2008\n\nAbstract: In the late 90's the emergence of high performance 3D commodity graphics cards opened the way to use PC clusters for high perfor- mance Virtual Reality (VR) applications. Today PC clusters are broadly used to drive multi projector immersive environments. In this paper, we survey the different approaches that have been developed to use PC clusters for VR applications. We review the most common software tools that enable to take advantage of the power of clusters. We also discuss some new trends.","Title: Web-Based Support For Resource-Effective E-Learning\nYear: 2006\n\nAbstract: This article presents work done at the Technical University of Lisbon, on web systems to support technology-enhanced learning. Based on eighteen months experience with webcast technologies and commonly used Learning Management Systems, this work has integrated both concepts and developed a simple, yet effective learning approach. This approach supports both students and professors in moving from the traditional classroom to technology-enhanced online settings. We present the evolution of our system and the results obtained from testing and evaluating the prototype, during the last Spring semester. One of the major features of our approach lies in combining both online and offline components of the e-Learning experience and incorporating desirable traits from traditional and technology-mediated learning. This way, we have identified significant issues for users in order to better manage the changes required to adapt our system to organizational processes and context of use. Our assessment points to changes in the teaching method, course organization, and highlights new factors of students' motivation. Results, however preliminary, seem to indicate both the usefulness of our approach and the feasibility of deploying e-learning initiatives with efforts optimization to complement traditional offerings in university settings.","Title: A comparative study of interaction metaphors for large-scale displays\nYear: 2009\n\nAbstract: Large-scale displays require new interaction techniques because of their physical size. There are technologies that tackle the problem of interaction with such devices by providing natural interaction to larger surfaces. We argue, however, that large-scale displays offer physical freedom that is not yet being applied to interaction. To better understand how distance affects user interaction, we present a comparative study of interaction metaphors for large-scale displays. We present three metaphors: Grab, Point and Mouse. The metaphors were included in our tests as we felt that each would be more suited to a specific distance: this is the focus of our tests. We then asked the users to solve a puzzle using those metaphors from different distances. We discovered that the point metaphor achieves better results on all tests. However, there is evidence that grab and mouse remain valid for specific tasks.","Title: Describing documents: what can users tell us?\nYear: 2004\n\nAbstract: With the increasing number of computers per user, it has become common for most users to deal with growing numbers of electronic documents. Those documents are usually stored in hierarchic file systems, requiring them to be classified into the hierarchy, a difficult task. Such organization schemes do not provide adequate support for the efficient and effortless retrieval of documents at a later time, since their position in the hierarchy is one of the only clues to a document's whereabouts. However, humans are natural-born storytellers, and stories help relate and remember important pieces of information. Hence, the usage of narratives where a user \"tells a story\" about the document will be a valuable tool towards simplifying the retrieval task.To find out if there are common patterns in stories about documents, we performed a study where 60 such stories were collected and analyzed. We identified the most common story elements (time, storage and purpose) and how they are likely to relate in typical stories. This preliminary study suggests that it is possible to infer archetypical stories. Further, we present a set of guidelines for the design of narrative-based document retrieval interfaces.","Title: Mockup builder: direct 3D modeling on and above the surface in a continuous interaction space\nYear: 2012\n\nAbstract: Our work introduces a semi-immersive environment for conceptual design where virtual mockups are obtained from gestures we aim to get closer to the way people conceive, create and manipulate three-dimensional shapes. We present on-and-above-the-surface interaction techniques following Guiard's asymmetric bimanual model to take advantage of the continuous interaction space for creating and editing 3D models in a stereoscopic environment. To allow for more expressive interactions, our approach continuously combines hand and finger tracking in the space above the table with multi-touch on its surface. This combination brings forth an alternative design environment where users can seamlessly switch between interacting on the surface or in the space above it depending on the task. Our approach integrates continuous space usage with bimanual interaction to provide an expressive set of 3D modeling operations. Preliminary trials with our experimental setup show this as a very promising avenue for further work.","Title: \"When i'm sixty-four...\": are there real strategies for providing universal accessibility for the elderly\nYear: 2002\n\nAbstract: In this panel we will present four strategies for providing computing for the elderly. We hope to generate discussion and ideas of the plusses and minuses of these strategies.","Title: Sketch-based retrieval of complex drawings using hierarchical topology and geometry\nYear: 2009\n\nAbstract: Due to the proliferation of drafting packages, there are a lot of vector drawings available for people to integrate into documents. Moreover, creative designers and drafts-people often reuse data from previous projects and libraries of ready-to-use components. Usually, retrieving these drawings is a slow, complex and error-prone endeavor. While text-driven attempts at classifying image data have been recently supplemented with query-by-image content, these work only for bitmap-type data and cannot handle vectorial information. Furthermore, they are not very good at retrieving partial information, which makes it difficult to search complex documents. Here we present a new approach to allow efficient retrieval of complex vector drawings by content using simple sketches as queries. Our work uses a new hierarchical topology description mechanism, which allows comparing complex drawings to simple queries. In particular, we produce a multilevel description of drawings, from the topology graph, using different levels of detail and subparts of the information. We also show that the graph spectrum is stable and reliable for use as a topology description. Finally, experimental tests show that our approach is good at retrieving complex drawings from two different application domains, CAD and clip-art figures.","Title: Telling stories to computers for document retrieval\nYear: 2004\n\nAbstract: The documents users must handle are growing both in number and diversity. However, the ways of organizing and retrieving them remain largely unchanged. Given the innate human ability to tell stories, the use of narratives can be a natural and effective way to retrieve documents. To better understand how narratives can be used in this context, a thorough characterization of their contents and structure was obtained from several interviews. Then, the results were validated by the evaluation of low fidelity prototypes for story-capture interfaces, allowing us to verify that stories are valid as document-retrieval tools, and the shape those interfaces should take (structured text entry).","Title: Understanding Individual Differences: Towards Effective Mobile Interface Design and Adaptation for the Blind.\nYear: 2014\n\nAbstract: No two people are alike. We usually ignore this diversity as we have the capability to adapt and, without noticing, become experts in interfaces that were probably misadjusted to begin with. This adaptation is not always at the user's reach. One neglected group is the blind. Spatial ability, memory, and tactile sensitivity are some characteristics that diverge between users. Regardless, all are presented with the same methods ignoring their capabilities and needs. Interaction with mobile devices is highly visually demanding which widens the gap between blind people. Our research goal is to identify the individual attributes that influence mobile interaction, considering the blind, and match them with mobile interaction modalities in a comprehensive and extensible design space. We aim to provide knowledge both for device design, device prescription and interface adaptation.","Title: Using autobiographic information to retrieve real and electronic documents\nYear: 2007\n\nAbstract: Current systems force users to store their documents in hierarchic filesystems. However, users remember their documents not in terms of ad-hoc categories, but of their contents, why they were written, etc. Describing documents using such autobiographic information would be a simpler and more effective way for users to retrieve them. Furthermore, we found that users mention printed versions of documents when retrieving them. However, current systems don't regard the printed and electronic versions of a document as facets of the same entity. To solve these problems we developed an interface that allows users to browse their autobiographic information, gathered by a special-purpose monitoring subsystem, to retrieve their documents. We bridged the gap between the real and electronic worlds by maintaining the association between paper and electronic documents resorting to RFID technology. Tests show our interface allows users to efficiently retrieve their documents.","Title: Evaluating adaptive user profiles for news classification\nYear: 2004\n\nAbstract: Never before have so many information sources been available. Most are accessible on-line and some exist on the Internet alone. However, this large information quantity makes interesting articles hard to find. Modern Personal Digital Assistants (PDAs), mobile phones, and the advent of ubiquitous computing will further complicate matters. Away from the desktop, the time to select important articles might be even harder to find. Strategies to select relevant information are sorely needed.One such strategy is content-based filtering, coupled with User Profiles. Our prototype uses a Bayesian classifier to select articles of interest to a specific user, according to his profile. The articles are extracted from web pages and displayed in a zoomable interface-based browser on a PDA. Interests may change over time, making it important to keep the profile up to date. The system monitors the users' reading behaviors, from which it infers their interest in particular articles and updates the profile accordingly. Results show that, from the start, most articles are correctly classified. An initial profile opposite to the user's actual interests can be reversed in less than ten days, showing the robustness of our approach. A user's interest in an article is inferred with a high degree of accuracy (over 90%).","Title: Understanding Stories about Personal Documents\nYear: 2008\n\nAbstract: Hierarchies are the most common way to help users organize their personal information. However, their use is fraught with problems. In particular, the users' documents, stored in the filesystem, are notoriously difficult to manage and retrieve. A way to alleviate those problems is to resort to a wide range of knowledge about the users, their actions and the world that surrounds them. Systems that have done so lack an organizing principle that helps users refer to all the information that might be relevant. We propose a novel user interface paradigm, narrative-based interfaces, that provides such an organizing principle, showing how knowledge plays a central role in understanding the users' stories. An analysis of Quill, a prototype narrative-based interface for personal document retrieval, will show how narratives can successfully be used to help users retrieve their documents.","Title: An haptic-based immersive environment for shape analysis and modelling\nYear: 2010\n\nAbstract: Currently, the design of aesthetic products is a process that requires a set of activities where digital models and physical mockups play a key role. Typically, these are modified (and built) several times before reaching the desired design, increasing the development time and, consequently, the final product cost. In this paper, we present an innovative design environment for computer-aided design (CAD) surface analysis. Our system relies on a direct visuo-haptic display system, which enables users to visualize models using a stereoscopic view, and allows the evaluation of sectional curves using touch. Profile curves are rendered using an haptic device that deforms a plastic strip, thanks to a set of actuators, to reproduce the curvature of the shape co-located with the virtual model. By touching the strip, users are able to evaluate shape characteristics, such as curvature or discontinuities (rendered using sound), and to assess the surface quality. We believe that future computer-aided systems (CAS)/CAD systems based on our approach will contribute in improving the design process at industrial level. Moreover, these will allow companies to reduce the product development time by reducing the number of physical mockups necessary for the product design evaluation and by increasing the quality of the final product, allowing a wider exploration and comparative evaluation of alternatives in the given time.","Title: Graphical Modeling and Calligraphic Interfaces\nYear: 2007\n\nAbstract: Summary form only given. CAD systems now enable us to manufacture complicated models. However, computers have yet to become usable at the very early stages of product design, where pencil and paper still reign. This is because present-day systems, with their focus on internal representation and dialogue hierarchies, require designers to leap large conceptual gaps when evolving from their idea of a desired object to the geometric model that formally expresses its intended shape. As computers become more sophisticated and powerful, alternative input modalities and interface techniques are emerging which form the basis for a new generation of sketching applications supporting what we call Calligraphic interfaces, where artificial dialogue constraints imposed by the previous generation of UIs are removed. We are exploring with minimalist approaches and techniques to approximate traditional methods including modeling, illustration and retrieval. I will talk about our research and ongoing projects at the Technical University of Lisbon, towards this goal.","Title: Sketch-based modeling: A survey\nYear: 2009\n\nAbstract: User interfaces in modeling have traditionally followed the WIMP (Window, Icon, Menu, Pointer) paradigm. Though functional and very powerful, they can also be cumbersome and daunting to a novice user, and creating a complex model requires considerable expertise and effort. A recent trend is toward more accessible and natural interfaces, which has lead to sketch-based interfaces for modeling (SBIM). The goal is to allow sketches—hasty freehand drawings—to be used in the modeling process, from rough model creation through to fine detail construction. Mapping a 2D sketch to a 3D modeling operation is a difficult task, rife with ambiguity. To wit, we present a categorization based on how a SBIM application chooses to interpret a sketch, of which there are three primary methods: to create a 3D model, to add details to an existing model, or to deform and manipulate a model. Additionally, in this paper we introduce a survey of sketch-based interfaces focused on 3D geometric modeling applications. The canonical and recent works are presented and classified, including techniques for sketch acquisition, filtering, and interpretation. The survey also provides an overview of some specific applications of SBIM and a discussion of important challenges and open problems for researchers to tackle in the coming years.","Title: A Simple Approach to Recognise Geometric Shapes Interactively\nYear: 1999\n\nAbstract: This paper presents a simple method to recognise multistroke sketches of geometric shapes. It uses temporal adjacency and global geometric properties of figures to recognise a simple vocabulary of geometric shapes including solid and dashed line styles, selection and delete gestures. The geometric features used (convex hull, smallest-area regular polygons, perimeter and area scalar ratios) are invariant with rotation and scale of figures. We have found the method very usable with acceptable recognition rates although the multi-stroke approach poses problems in choosing appropriate values for time-outs. Although we have privileged simplicity over robustness, the method has proved suitable for interactive applications.","Title: Conceptual Design And Prototyping To Explore Creativity\nYear: 2007\n\nAbstract: Many approaches to teaching HCI focus on either user requirements or prototyping. However, these two techniques do not provide enough tools for Students to explore the design space in breadth at early stages of conception. Indeed, even when these two approaches are combined, students still lack tools to explore the design space and bridge the gap from requirements to prototyping. In this paper, we describe the way we teach Human Computer Interaction, stimulating students to be creative during interface design. To that end we added course materials on conceptual design and scenario based interaction, combined with the exploration of different low fidelity prototypes, which we believe increase both the usability of student-developed prototypes and foster learner creativity. To illustrate this we present some of the best examples of interactive prototypes designed and developed by Students attending our HCI Course in the context of Information Systems and Computer Engineering (ISCE) curriculum at the Technical University of Lisbon, Portugal. While the current approach seems to elicit positive responses and draw encouraging remarks from Students, work remains to be done in emerging interface paradigms and more formal evaluation on how this approach positively affects student outcomes.","Title: Title of tutorial: Designing immersive VR systems: From bits to bolts\nYear: 2012\n\nAbstract: Immersive 3D Virtual Environments (VE) have become affordable for many research centers. However, a complete solution needs several integration steps to be fully operational. Some of these steps are difficult to accomplish and require an uncommon combination of different skills. This tutorial presents the most recent techniques developed to address this problem, from displays to software tools. The hardware in a typical VR installations combines projectors, screens, speakers, computers, tracking and I/O devices. The tutorial will discuss hardware options, explaining their advantages and disadvantages. We will cover design decisions from basic software and hardware design, through user tracking, multimodal human-computer interfaces and acoustic rendering, to how to administrate the whole solution. Additionally, we will provide an introduction to existing tracking technologies, explaining how the most common devices work, while focusing on infrared optical tracking. Finally, we briefly cover integration software and middleware developed for most VE settings.","Title: Title of tutorial: Designing immersive VR systems: From bits to bolts\nYear: 2012\n\nAbstract: Immersive 3D Virtual Environments (VE) have become affordable for many research centers. However, a complete solution needs several integration steps to be fully operational. Some of these steps are difficult to accomplish and require an uncommon combination of different skills. This tutorial presents the most recent techniques developed to address this problem, from displays to software tools. The hardware in a typical VR installations combines projectors, screens, speakers, computers, tracking and I/O devices. The tutorial will discuss hardware options, explaining their advantages and disadvantages. We will cover design decisions from basic software and hardware design, through user tracking, multimodal human-computer interfaces and acoustic rendering, to how to administrate the whole solution. Additionally, we will provide an introduction to existing tracking technologies, explaining how the most common devices work, while focusing on infrared optical tracking. Finally, we briefly cover integration software and middleware developed for most VE settings.","Title: Augmenting touch interaction through acoustic sensing\nYear: 2011\n\nAbstract: Recognizing how a person actually touches a surface has generated a strong interest within the interactive surfaces community. Although we agree that touch is the main source of information, unless other cues are accounted for, user intention might not be accurately recognized. We propose to expand the expressiveness of touch interfaces by augmenting touch with acoustic sensing. In our vision, users can naturally express different actions by touching the surface with different body parts, such as fingers, knuckles, fingernails, punches, and so forth - not always distinguishable by touch technologies but recognized by acoustic sensing. Our contribution is the integration of touch and sound to expand the input language of surface interaction.","Title: Handling Ambiguity and Errors: Visual Languages for Calligraphic Interaction\nYear: 2001\n\nAbstract: This paper describes error handling and ambiguity in a class of applications organized around drawing and sketching, which we call Calligraphic Interfaces.While errors and imprecision are unavoidable features of human input, these have long been considered nuisances and problems to circumvent in user interface design.However, the transition away from non-WIMP interface styles and into continuous media featuring recognition requires that we take a fresh approach to errors and imprecision.We present new tools and interaction styles to allow designers to develop error tolerant and simpler interaction dialogues.","Title: From Tapping to Touching: Making Touch Screens Accessible to Blind Users\nYear: 2008\n\nAbstract: The NavTouch navigational method enables blind users to input text in a touch-screen device by performing directional gestures to navigate a vowel-indexed alphabet.","Title: InStory: a system for mobile information access, storytelling and gaming activities in physical spaces\nYear: 2005\n\nAbstract: This paper describes the work carried out in the InStory project. InStory has the goal of defining and implementing a platform for mobile storytelling, information access, and gaming activities. The platform has a flexible computational architecture that integrates heterogeneous devices, different media formats and computational support for different narrative modes and gaming activities. The system is driven and validated by a set of story threads and narratives that are centered on the exploration of physical spaces. This exploration is combined with the perspective of sharing information between users and providing historic context. The project also wants to explore the social aspect of shared narratives and activities, with the idea that the technology can provide new innovative approaches to social participation in different types of events.","Title: Interactive installations: tales from the trenches\nYear: 2011\n\nAbstract: Breakthrough innovation can be interpreted as research translated into products that the market accepts. The process of market translation of several products developed by WowSystems, a Portuguese company specialized in novel interaction paradigms, is explained in this paper as a case study shedding some light into how innovation centers can better promote innovation, in the form of well-succeeded products. We describe two paradigmatic \"tales from the trenches\" and conclude with some guidelines that were outlined on the basis of more than three years delivering fifty interactive installations.","Title: EC/NSF workshop on universal accessibility of ubiquitous computing: providing for the elderly event report\nYear: 2001\n\nAbstract: The workshop took place on Alcácer do Sal, Portugal from May 22nd to May 25th, 2001 with the purpose to discuss approaches to universal usability for the elderly constituency. Elderly citizens are a growing age group within developed countries and their needs have been mostly ignored by Information Technology and Computing as a whole. The surge of mobile communications and universal access materialized in the push for UMTS in Europe provided a strong leitmotif for this meeting. For the better part of a week, a group joining twenty-six people from several different communities gathered to discuss strategic issues arising from the new context. The aim is to provide strategic inputs for major research programs in EU, USA and Japan. The present document contains a summary account of the proceedings.","Title: Refereed digital publication of computer graphics educational materials\nYear: 2004\n\nAbstract: Computer Graphics (CG) as a discipline has undergone drastic modifications over the past decades. Indeed the phenomenal progress in both the technical and digital art domains requires educators to master new content and achieve deeper understandings of computers and imagery if they are to keep up with the pace of change. Moreover, as the core field matures, educators in all areas experience a greater need for high-quality curricular resources. Thus, offering excellent educational materials online is an important service to the community. Such support will empower both young and seasoned educators alike to benefit from and contribute to the work of others.","Title: Experimental Evaluation of a Trainable Scribble Recognizer for Calligraphic Interfaces\nYear: 2001\n\nAbstract: This paper describes a trainable recognizer for hand-drawn sketches using geometric features. We compare three different learning algorithms and select the best approach in terms of cost-performance ratio. The algorithms employ classic machine-learning techniques using a clustering approach. Experimental results show competing performance (95.1%) with the non-trainable recognizer (95.8%) previously developed, with obvious gains in flexibility and expandability. In addition, we study both their classification and learning performance with increasing number of examples per class.","Title: Identifying Student Types In A Gamified Learning Experience\nYear: 2014\n\nAbstract: Gamification of education is a recent trend, and early experiments showed promising results. Students seem not only to perform better, but also to participate more and to feel more engaged with gamified learning. However, little is known regarding how different students are affected by gamification and how their learning experience may vary. In this paper the authors present a study in which they analyzed student data from a gamified college course and looked for distinct behavioral patterns. The authors clustered students according to their performance throughout the semester, and carried out a thorough analysis of each cluster, regarding many aspects of their learning experience. They clearly found three types of students, each with very distinctive strategies and approaches towards gamified learning: the Achievers, the Disheartened and the Underachievers. A careful analysis allowed them to extensively describe each student type and derive meaningful guidelines, to help carefully tailoring custom gamified experiences for them.","Title: Mobile touchscreen user interfaces: bridging the gap between motor-impaired and able-bodied users\nYear: 2014\n\nAbstract: Touchscreen mobile devices are highly customizable, allowing designers to create inclusive user interfaces that are accessible to a broader audience. However, the knowledge to provide this new generation of user interfaces is yet to be uncovered. The goal was to thoroughly study mobile touchscreen interfaces and provide guidelines for informed design. The paper presents an evaluation performed with 15 tetraplegic and 18 able-bodied users that allowed to identify their main similarities and differences within a set of interaction techniques (Tapping, Crossing, and Directional Gesturing) and parameterizations. Results show that Tapping and Crossing are the most similar and easy to use techniques for both motor-impaired and able-bodied users. Regarding Tapping, error rates start to converge at 12 mm, showing to be a good compromise for target size. As for Crossing, it offered a similar level of accuracy; however, larger targets (17 mm) are significantly easier to cross for motor-impaired users. Directional Gesturing was the least inclusive technique. Regarding position, edges showed to be troublesome. For instance, they have shown to increase Tapping precision for disabled users, while decreasing able-bodied users' accuracy when targets are too small (7 mm). It is argued that despite the expected error rate disparity, there are clear resemblances between user groups, thus enabling the development of inclusive touch interfaces. Tapping, a traditional interaction technique, was among the most effective for both target populations, along with Crossing. The main difference concerns Directional Gesturing that in spite of its unconstrained nature shows to be inaccurate for motor-impaired users.","Title: Mobile text-entry and visual demands: reusing and optimizing current solutions\nYear: 2014\n\nAbstract: Mobile devices are increasingly used for text-entry in contexts where visual attention is fragmented and graphical information is inadequate, yet the current solutions to typing on virtual keyboards make it a visually demanding task. This work looks at assistive technologies and interface attributes as tools to ease the task. Two within-subject experiments were performed with 23 and 17 participants, respectively. The first experiment aimed to understand how walking affected text-entry performance and additionally to assess how effective assistive technologies can be in mobile contexts. In the second experiment, adaptive keyboards featuring character prediction and pre-attentive attributes to ease visual demands of text-entry interfaces were developed and evaluated. It has been found that both text-input speed and overall quality are affected in mobile situations. Contrary to the expectations, assistive technologies proved ineffective with visual feedback. The second experiment showed that pre-attentive attributes do not affect users' performance in task-entry tasks, even though a 3.3---4.3 % decrease in error rates was measured. It was found that users reduce walking speed to compensate for challenges placed by mobile text-entry. Caution should be exercised when transferring assistive technologies to mobile contexts, since they need adaptations to address mobile users' needs. Also, while pre-attentive attributes seemingly have no effect on experienced QWERTY typists' performance, they showed promise for both novice users and typists in attention-demanding contexts.","Title: Physio@Home: Exploring Visual Guidance and Feedback Techniques for Physiotherapy Exercises\nYear: 2015\n\nAbstract: Physiotherapy patients exercising at home alone are at risk of re-injury since they do not have corrective guidance from a therapist. To explore solutions to this problem, we designed Physio@Home, a prototype that guides people through prerecorded physiotherapy exercises using real-time visual guides and multi-camera views. Our design addresses several aspects of corrective guidance, including: plane and range of movement, joint positions and angles, and extent of movement. We evaluated our design, com-paring how closely people could follow exercise movements under various feedback conditions. Participants were most accurate when using our visual guide and multi-views. We provide suggestions for exercise guidance systems drawn from qualitative findings on visual feedback complexity.","Title: ThumbCam: Returning to single touch interactions to explore 3D virtual environments\nYear: 2014\n\nAbstract: Three-dimensional virtual environments are present in many different applications, being used even in small handheld devices. To navigate in these environments using such devices, most of current solutions rely on multi-touch interactions. However, previous works have already stated that multi-touch gestures on smartphones are not always feasible. In this work we present ThumbCam, a novel single-touch technique for camera manipulation on 3D virtual environments. With our solution, the user is able to move and look around and circle points of interest, while interacting using only his thumb. We compare ThumbCam with other state-of-the-art techniques, showing that it can offer more operations with a single touch. A qualitative user evaluation revealed that users found our solution appealing.","Title: Interactive two-sided transparent displays: designing for collaboration\nYear: 2014\n\nAbstract: Transparent displays can serve as an important collaborative medium supporting face-to-face interactions over a shared visual work surface. Such displays enhance workspace awareness: when a person is working on one side of a transparent display, the person on the other side can see the other's body, hand gestures, gaze and what he or she is actually manipulating on the shared screen. Even so, we argue that designing such transparent displays must go beyond current offerings if it is to support collaboration. First, both sides of the display must accept interactive input, preferably by at least touch and / or pen, as that affords the ability for either person to directly interact with the workspace items. Second, and more controversially, both sides of the display must be able to present different content, albeit selectively. Third (and related to the second point), because screen contents and lighting can partially obscure what can be seen through the surface, the display should visually enhance the actions of the person on the other side to better support workspace awareness. We describe our prototype FACINGBOARD-2 system, where we concentrate on how its design supports these three collaborative requirements.","Title: Combining EEG Data with Place and Plausibility Responses as an Approach to Measuring Presence in Outdoor Virtual Environments\nYear: 2014\n\nAbstract: Outdoor virtual environments (OVEs) are becoming increasingly popular, as they allow a sense of presence in places that are inaccessible or protected from human intervention. These virtual environments (VEs) need to address physical modalities other than vision and hearing. We analyze the influence of four different physical modalities (vision, hearing, haptics, and olfaction) on the sense of presence on a virtual journey through the sea and the Laurissilva Forest of Funchal, Portugal. We applied Slater et al.'s (2010) method together with data gathered by the Emotiv EPOC EEG in an OVE setting. In such a setting, the combination of haptics and hearing are more important than the typical virtual environment (vision and hearing) in terms of place and plausibility illusions. Our analysis is particularly important for designers interested in crafting similar VEs because we classify different physical modalities according to their importance in enhancing presence.","Title: Using fuzzy logic to recognize geometric shapes interactively\nYear: 2000\n\nAbstract: This paper presents a simple method, based on fuzzy logic, to recognize multi-stroke sketches of geometric shapes and uni-stroke gestural commands. It uses temporal adjacency and global geometric properties of figures to recognize a simple vo- cabulary of geometric shapes drawn in different line styles. The geometric features used (convex hull, largest-area inscribed and smallest-area enclosing polygons, perimeter and area ratios) are invariant with rotation and scale of figures. Through experimen- tal evaluation we have found the method very usable with accept- able recognition rates although the multi-stroke approach poses problems in choosing appropriate values for timeouts. Although we have privileged simplicity over robustness, the method has proved suitable for interactive applications.","Title: Visual languages for sketching documents\nYear: 2000\n\nAbstract: We present a visual approach to layout documents as hand-drawn compositions of simple geometric shapes. This approach is based on a grammatical method to support document design through sketch recognition which explicitly addresses visual ambiguity. We use fuzzy relational adjacency grammars to provide a natural handling of fuzzy logic and spatial relation syntax in a single unified formalism. Fuzzy relations enable us to replace spatial constraints such as “a is above b” or “a is parallel to c” by quantities that express a degree of uncertainty. Their use allows us to associate a “measure of goodness” to all data and to intermediate and final results. We developed a prototype application that supports document layout sketching in a simple way","Title: A Survey on Implicit Surface Polygonization\nYear: 2015\n\nAbstract: Implicit surfaces (IS) are commonly used in image creation, modeling environments, modeling objects, and scientific data visualization. In this article, we present a survey of different techniques for fast visualization of IS. The main classes of visualization algorithms are identified along with the advantages of each in the context of the different types of IS commonly used in computer graphics. We focus closely on polygonization methods, as they are the most suited to fast visualization. Classification and comparison of existing approaches are presented using criteria extracted from current research. This enables the identification of the best strategies according to the number of specific requirements, such as speed, accuracy, quality, or stylization.","Title: Clustering Students Based on Motivation to Learn: A Blended Learning Approach\nYear: 2015\n\nAbstract: Technological advances during the last decade have provided huge possibilities to support e-learning. However, there are still concerns regarding Return-on-Investment ROI of e-learning, its sustainability within organizational bound-aries and effectiveness across potential learner groups. Much previous research has concentrated on learners' motivation, satisfaction, and retention. This leaves room for further research to identify alternative and innovative ways to center design on students' concerns when learning online. The authors' work focuses on designing workable courseware usability evaluation methods to differentiate students to improve learning-support frameworks from both pedagogical and system perspectives. The authors' results suggest that students can be grouped in three clusters based on their motivation to e-Learn. Instructors could predict which cluster a new student belongs to, making it possible to anticipate usability issues that most affect results. This also facilitates pedagogical interventions that could help at-risk learners, contributing to the retention rate.","Title: Expeditious illustration of layer-cake models on and above a tactile surface.\nYear: 2016\n\nAbstract: Too often illustrating and visualizing 3D geological concepts are performed by sketching in 2D mediums, which may limit drawing performance of initial concepts. Here, the potential of expeditious geological modeling brought by hand gestures is explored. A spatial interaction system was developed to enable rapid modeling, editing, and exploration of 3D layer-cake objects. User interactions are acquired with motion capture and touch screen technologies. Virtual immersion is guaranteed by using stereoscopic technology. The novelty consists of performing expeditious modeling of coarse geological features with only a limited set of hand gestures. Results from usability-studies show that the proposed system is more efficient when compared to a windows-icon-menu-pointer modeling application. Display Omitted New spatial interaction system to rapidly sketch and explore geological models.Stereoscopic visualization approach to direct manipulation in 3-space.Approach uses the continuous interaction space over a multi-touch surface.Comparative study shows advantage over a mouse+keyboard approach.User study identifies a more efficient solution to model layer-caked models.","Title: Building the world-wide community of graphics educators\nYear: 2004\n\nAbstract: The fast pace of change in the computer graphics (CG) field makes it difficult for educators to continually design up to date, meaningful and robust curricula that address the full potential of the technology. We feel that the most valuable resource for CG educators is access to an international community of people who teach digital media in all forms. This forum will be a discussion about how we can build that community and how we can provide a method for the people involved to share information.","Title: Computer graphics educational materials source policies and status report\nYear: 2004\n\nAbstract: CGEMS, the Computer Graphics Educational Materials Source, aims at supporting a worldwide community of Computer Graphics educators. Our goal in developing this service is to provide a means for educators' work to be appraised and disseminated to other members of the community through an online server for refereed educational content. Since it was presented last year at SIGGRAPH in San Diego, CGEMS has evolved into a full-fledged peer-reviewed medium. This paper presents the current state of the server, reports on work developed and dissemination activities, but most importantly describes how and why educators should submit content.","Title: SleeveAR: Augmented Reality for Rehabilitation using Realtime Feedback.\nYear: 2016\n\nAbstract: We present an intelligent user interface that allows people to perform rehabilitation exercises by themselves under the offline supervision of a therapist. Every year, many people suffer injuries that require rehabilitation. This entails considerable time overheads since it requires people to perform specified exercises under the direct supervision of a therapist. Therefore it is desirable that patients continue performing exercises outside the clinic (for instance at home, thus without direct supervision), to complement in-clinic physical therapy. However, to perform rehabilitation tasks accurately, patients need appropriate feedback, as otherwise provided by a physical therapist, to ensure that these unsupervised exercises are correctly executed. Different approaches address this problem, providing feedback mechanisms to aid rehabilitation. Unfortunately, test subjects frequently report having trouble to completely understand the feedback thus provided, which makes it hard to correctly execute the prescribed movements. Worse, injuries may occur due to incorrect performance of the prescribed exercises, which severely hinders recovery. SleeveAR is a novel approach to provide real-time, active feedback, using multiple projection surfaces to provide effective visualizations. Empirical evaluation shows the effectiveness of our approach as compared to traditional video-based feedback. Our experimental results show that our intelligent UI can successfully guide subjects through an exercise prescribed (and demonstrated) by a physical therapist, with performance improvements between consecutive executions, a desirable goal to successful rehabilitation.","Title: Eery Space: Facilitating Virtual Meetings Through Remote Proxemics\nYear: 2015\n\nAbstract: Virtual meetings have become increasingly common with modern video-conference and collaborative software. While they allow obvious savings in time and resources, current technologies add unproductive layers of protocol to the flow of communication between participants, rendering the interactions far from seamless. In this work we introduce Remote Proxemics, an extension of proxemics aimed at bringing the syntax of co-located proximal interactions to virtual meetings. We propose Eery Space, a shared virtual locus that results from merging multiple remote areas, where meeting participants' are located side-by-side as if they shared the same physical location. Eery Space promotes collaborative content creation and seamless mediation of communication channels based on virtual proximity. Results from user evaluation suggest that our approach is sufficient to initiate proximal exchanges regardless of their geolocation, while promoting smooth interactions between local and remote people alike.","Title: Mixing images and sketches for retrieving vector drawings\nYear: 2004\n\nAbstract: Current approaches to content-based retrieval of multimedia data usually rely either on query by example or on sketches of the desired image, but not on both. In this paper, we propose a new query specification scheme, where digital images are combined with sketches, after vectorization, taking advantage of both methods. We selected a set of algorithms to perform image vectorization, taking into account the trade-off between vector image quality and processing time. This method of specifying queries is part of a system to retrieve vector drawings, which we briefly describe in this paper.","Title: Sketch-Based Mesh Augmentation\nYear: 2005\n\nAbstract: This paper describes a sketch-based method for augmenting geometric meshes with variable-scale sharp features. Such mesh editing operations provide a powerful way to exploit artist's natural sketching abilities for content creation using existing mesh libraries. We use adaptive subdivision to refine the mesh only in the region of the features and embed the augmentations into the input mesh, maintaining a unified representation. Moreover, we present new templates for adaptive subdivision that minimizes the high-valence vertex count while maximizing the number of quadrilaterals in the new mesh, thereby improving its quality.","Title: Cascading recognizers for ambiguous calligraphic interaction\nYear: 2004\n\nAbstract: Throughout the last decade many approaches have been made to the problem of developing CAD systems that are usable in the early stages of product ideation. Although most of these approaches rely on some kind of drawing paradigm and on the paper-and-pencil metaphor, only a few of them deal with the ambiguity that is inherent to natural languages in general and to sketching in particular. Also the paper-and-pencil metaphor has not in most cases been fully accomplished, since many gesture-based interfaces resort to secondary buttons and modifier keys in order to make command strokes easier to differentiate from their geometry instantiating counterparts. In this paper we describe the architecture of GIDeS++, a sketch-based 3D modeling system that approaches these problems in three different ways: by dealing with ambiguity and exploring it to the user's benefit; by reducing the command set and thus minimizing the cognitive load on the user; and by cascading different types of gesture recognizers, which allows interaction to resort only to the button located on the tip of an electronic stylus.","Title: Relating gaming habits with student performance in a gamified learning experience\nYear: 2014\n\nAbstract: Gamified education is a novel concept, and early trials show its potential to engage students and improve their performance. However, little is known about how different students learn with gamification, and how their gaming habits influence their experience. In this paper we present a study where data regarding student performance and gaming preferences, from a gamified engineering course, was collected and analyzed. We performed cluster analysis to understand what different kinds of students could be observed in our gamified experience, and how their behavior could be correlated to their gaming characteristics. We identified four main student types: the Achievers, the Regular students, the Halfhearted students, and the Underachievers, all representing different strategies towards the course and with different gaming preferences. Here we will thoroughly describe each student type and address how different gaming preferences might have impacted the students' learning experience.","Title: Accelerating Occlusion Rendering on a GPU via Ray Classification.\nYear: 2015\n\nAbstract: Accurately rendering occlusions is required when ray-tracing objects to achieve more realistic rendering of scenes. Indeed, soft phenomena such as shadows and ambient occlusion can be achieved with stochastic ray tracing techniques. However, computing randomized incoherent ray-object intersections can be inefficient. This is problematic in Graphics Processing Unit GPU applications, where thread divergence can significantly lower throughput. The authors show how this issue can be mitigated using classification techniques that sort rays according to their spatial characteristics. Still, classifying occlusion terms requires sorting millions of rays. This is offset by savings in rendering time, which result from a more coherent ray distribution. The authors survey and test different ray classification techniques to identify the most effective. The best results were achieved when sorting rays using a compress-sort-decompress approach using 32-bit hash keys.","Title: Early Prediction of Student Profiles Based on Performance and Gaming Preferences.\nYear: 2016\n\nAbstract: State of the art research shows that gamified learning can be used to engage students and help them perform better. However, most studies use a one-size-fits-all approach to gamification, where individual differences and needs are ignored. In a previous study, we identified four types of students attending a gamified college course, characterized by different levels of performance, engagement and ...","Title: Talaria: Continuous Drag & Drop on a Wall Display.\nYear: 2016\n\nAbstract: We present an interaction technique combining tactile actions and midair pointing to access out-of-reach content on large displays without the need to walk across the display. Users can start through a touch gesture on the display surface and finish midair by pointing to push content away or inversely to retrieve a content. The technique takes advantage of well-known semantics of pointing in human-to-human interaction. These, coupled with the semantics of proximal relations and deictic proxemics make the proposed technique very powerful as it leverages on well-understood human-human interaction modalities. Experimental results show this technique to outperform direct tactile interaction on dragging tasks. From our experience we derive four guidelines for interaction with large-scale displays.","Title: Effects of speed and transitions on target-based travel techniques.\nYear: 2016\n\nAbstract: Travel on Virtual Environments is the simple action where a user moves from a starting point A to a target point B. Choosing an incorrect type of technique could compromise the Virtual Reality experience and cause side effects such as spatial disorientation, fatigue and cybersickness. The design of effective travelling techniques demands to be as natural as possible, thus real walking techniques presents better results, despite their physical limitations. Approaches to surpass these limitations employ techniques that provide an indirect travel metaphor such as point-steering and target-based. In fact, target-based techniques evince a reduction in fatigue and cybersickness against the point-steering techniques, even though providing less control. In this paper we investigate further effects of speed and transition on target-based techniques on factors such as comfort and cybersickness using a Head-Mounted Display setup.","Title: The benefits of DOF separation in mid-air 3D object manipulation.\nYear: 2016\n\nAbstract: Object manipulation is a key feature in almost every virtual environment. However, it is difficult to accurately place an object in immersive virtual environments using mid-air gestures that mimic interactions in the physical world, although being a direct and natural approach. Previous research studied mouse and touch based interfaces concluding that separation of degrees-of-freedom (DOF) led to improved results. In this paper, we present the first user evaluation to assess the impact of explicit 6 DOF separation in mid-air manipulation tasks. We implemented a technique based on familiar virtual widgets that allow single DOF control, and compared it against a direct approach and PRISM, which dynamically adjusts the ratio between hand and object motions. Our results suggest that full DOF separation benefits precision in spatial manipulations, at the cost of additional time for complex tasks. From our results we draw guidelines for 3D object manipulation in mid-air.","Title: Perceiving depth: optical versus video see-through.\nYear: 2016\n\nAbstract: Head-Mounted Displays (HMDs) and similar 3D visualization devices are becoming ubiquitous. Going a step forward, HMD see-through systems bring virtual objects to real world settings, allowing augmented reality to be used in complex engineering scenarios. Of these, optical and video see-through systems differ on how the real world is captured by the device. To provide a seamless integration of real and virtual imagery, the absolute depth and size of both virtual and real objects should match appropriately. However, these technologies are still in their early stages, each featuring different strengths and weaknesses which affect the user experience. In this work we compare optical to video see-through systems, focusing on depth perception via exocentric and egocentric methods. Our study pairs Meta Glasses, an off-the-shelf optical see-through, to a modified Oculus Rift setup with attached video-cameras, for video see-through. Results show that, with the current hardware available, the video see-through configuration provides better overall results. These experiments and our results can help interaction designers for both virtual and augmented reality conditions.","Title: Multi-GPU-based detection of protein cavities using critical points.\nYear: 2017\n\nAbstract: Protein cavities are specific regions on the protein surface where ligands (small molecules) may bind. Such cavities are putative binding sites of proteins for ligands. Usually, cavities correspond to voids, pockets, and depressions of molecular surfaces. The location of such cavities is important to better understand protein functions, as needed in, for example, structure-based drug design. This article introduces a geometric method to detecting cavities on the molecular surface based on the theory of critical points. The method, called CriticalFinder, differs from other surface-based methods found in the literature because it directly uses the curvature of the scalar field (or function) that represents the molecular surface, instead of evaluating the curvature of the Connolly function over the molecular surface. To evaluate the accuracy of CriticalFinder, we compare it to other seven geometric methods (i.e., LIGSITECS, GHECOM, ConCavity, POCASA, SURFNET, PASS, and Fpocket). The benchmark results show that CriticalFinder outperforms those methods in terms of accuracy. In addition, the performance analysis of the GPU implementation of CriticalFinder in terms of time consumption and memory space occupancy was carried out.","Title: Studying student differentiation in gamified education: A long-term study.\nYear: 2017\n\nAbstract: Gamified learning is a novel concept that according to recent studies, can increase student activity and improve learning outcomes. However, little is known about how different students experience and are engaged by it. We present a long-term study which identified distinct behavioral and performance patterns in participants taking a gamified college course. Our study lasted for three years, during which we deployed three consecutive instances of the course, each featuring improvements based on student feedback from the previous instances. To understand how different students behaved in our gamified experience, according to their daily performance, we performed cluster analysis and assessed student engagement in the last year using a formal instrument. We then did a cluster-wise analysis using different performance and behavioral measures, to further assess and characterize every cluster. To wit, we identified six different student clusters, each featuring different behaviors and performance levels. However, only four were present in the last year, which differed in terms of engagement with the course. In this paper we carefully describe each student cluster, explain how they evolved, and derive meaningful design lessons.","Title: Hip-directed walking-in-place using a single depth camera.\nYear: 2017\n\nAbstract: Walking-in-place (WIP) is a locomotion technique that allows users to travel in virtual environments (VEs) without significantly changing their physical position on the floor. Hip-directed steering(HDS) is a novel physical technique for controlling direction changes in virtual travel using hip movements. We present an WIP-based navigation approach for controlling locomotion in VEs that combines the speed and direction in a scenario similar to a domestic setup in which people interact with a flat screen. Their physical motion data are captured by one depth camera properly aligned with the screen and oriented toward the user.","Title: Using custom transformation axes for mid-air manipulation of 3D virtual objects\nYear: 2017\n\nAbstract: Virtual Reality environments are able to offer natural interaction metaphors. However, it is difficult to accurately place virtual objects in the desired position and orientation using gestures in mid-air. Previous research concluded that the separation of degrees-of-freedom (DOF) can lead to better results, but these benefits come with an increase in time when performing complex tasks, due to the additional number of transformations required. In this work, we assess whether custom transformation axes can be used to achieve the accuracy of DOF separation without sacrificing completion time. For this, we developed a new manipulation technique, MAiOR, which offers translation and rotation separation, supporting both 3-DOF and 1-DOF manipulations, using personalized axes for the latter. Additionally, it also has direct 6-DOF manipulation for coarse transformations, and scaled object translation for increased placement. We compared MAiOR against an exclusively 6-DOF approach and a widget-based approach with explicit DOF separation. Results show that, contrary to previous research suggestions, single DOF manipulations are not appealing to users. Instead, users favored 3-DOF manipulations above all, while keeping translation and rotation independent.","Title: Design and evaluation of a novel out-of-reach selection technique for VR using iterative refinement.\nYear: 2017\n\nAbstract: •A taxonomy to classify reach, cardinality and refinement on out-of-reach selections.•We propose PRECIOUS, a novel out-of-reach selection technique.•PRECIOUS employs an iterative progressive refinement strategy in Virtual Reality.•User evaluation comparing PRECIOUS against state-of-the-art out-of-reach approaches.•PRECIOUS is a versatile approach, combining accuracy with consistent selection times.","Title: Geometric Detection Algorithms for Cavities on Protein Surfaces in Molecular Graphics: A Survey.\nYear: 2017\n\nAbstract: Detecting and analysing protein cavities provides significant information about active sites for biological processes (e.g. protein-protein or protein-ligand binding) in molecular graphics and modelling. Using the three-dimensional (3D) structure of a given protein (i.e. atom types and their locations in 3D) as retrieved from a PDB (Protein Data Bank) file, it is now computationally viable to determine a description of these cavities. Such cavities correspond to pockets, clefts, invaginations, voids, tunnels, channels and grooves on the surface of a given protein. In this work, we survey the literature on protein cavity computation and classify algorithmic approaches into three categories: evolution-based, energy-based and geometry-based. Our survey focuses on geometric algorithms, whose taxonomy is extended to include not only sphere-, grid- and tessellation-based methods, but also surface-based, hybrid geometric, consensus and time-varying methods. Finally, we detail those techniques that have been customized for GPU (graphics processing unit) computing.","Title: Using iterative refinement for out-of-reach selection in VR.\nYear: 2017\n\nAbstract: In Virtual Reality (VR), the action of selecting virtual objects outside arms-reach still poses significant challenges. In this work, after classifying, with a new taxonomy, and analyzing existing solutions, we propose a novel technique to perform out-of-reach selections in VR. It uses natural pointing gestures, a modifiable cone as selection volume, and an iterative progressive refinement strategy. This can be considered a VR implementation of a discrete zoom approach, although we modify usersu0027 position instead of the field-of-view. When the cone intersects several objects, users can either activate the refinement process, or trigger a multiple object selection. We compared our technique against two techniques from literature. Our results show that, although not being the fastest, it is a versatile approach due to the lack of errors and uniform completion times.","Title: Assessing the usability of tile-based interfaces to visually navigate 3-D parameter domains.\nYear: 2018\n\nAbstract: •A generic tile-based interface is proposed to navigate 3D parameter spaces.•Users easily navigate along tiles arranged in a rhombille pattern.•Usability study reveals similar performance results between tile-based, 1-D sliders and specialized widgets.•Tile-based interfaces are suitable to navigate color and super-shape spaces.•Rotation space navigation is more challenging via tile-based interface.","Title: Explicit design of transfer functions for volume-rendered images by combining histograms, thumbnails, and sketch-based interaction.\nYear: 2018\n\nAbstract: Visual quality of volume rendering for medical imagery strongly depends on the underlying transfer function. Conventional Windows–Icons–Menus–Pointer interfaces typically refer the user to browse a lengthy catalog of predefined transfer functions or to pain-staking refine the transfer function by clicking and dragging several independent handles. To turn the standard design process less difficult and tedious, this paper proposes novel interactions on a sketch-based interface that supports the design of 1D transfer functions via touch gestures to directly control voxel opacity and easily assign colors. User can select different types of transfer function shapes including ramp function, free hand curve drawing, and slider bars similar to those of a mixing table. An assorted array of thumbnails provides an overview of the data when editing the transfer function. User performance is evaluated by comparing the time and effort necessary to complete a number of tests with sketch-based and conventional interfaces. Users were able to more rapidly explore and understand volume data using the sketch-based interface, as the number of design iterations necessary to obtain a desirable transfer function was reduced. In addition, informal evaluation sessions carried out with professionals (two senior radiologists, a general surgeon and two scientific illustrators) provided valuable feedback on how suitable the sketch-based interface is for illustration, patient communication and medical education.","Title: Keep my head on my shoulders!: why third-person is bad for navigation in VR\nYear: 2018\n\nAbstract: Head-Mounted Displays are useful to place users in virtual reality (VR). They do this by totally occluding the physical world, including users' bodies. This can make self-awareness problematic. Indeed, researchers have shown that users' feeling of presence and spatial awareness are highly influenced by their virtual representations, and that self-embodied representations (avatars) of their anatomy can make the experience more engaging. On the other hand, recent user studies show a penchant towards a third-person view of one's own body to seemingly improve spatial awareness. However, due to its unnaturality, we argue that a third-person perspective is not as effective or convenient as a first-person view for task execution in VR. In this paper, we investigate, through a user evaluation, how these perspectives affect task performance and embodiment, focusing on navigation tasks, namely walking while avoiding obstacles. For each perspective, we also compare three different levels of realism for users' representation, specifically a stylized abstract avatar, a mesh-based generic human, and a real-time point-cloud rendering of the users' own body. Our results show that only when a third-person perspective is coupled with a realistic representation, a similar sense of embodiment and spatial awareness is felt. In all other cases, a first-person perspective is still better suited for navigation tasks, regardless of representation.","Title: A New Approach To Walking In Place\nYear: 2013\n\nAbstract: Walking in Place (WIP) is an important locomotion technique used in virtual environments. This paper proposes a new approach to WIP, called Speed-Amplitude-Supported Walking-in-Place (SAS-WIP), which allows people, when walking along linear paths, to control their virtual speed based on footstep amplitude and speed metrics. We argue that our approach allows users to better control the virtual distance covered by the footsteps, achieve higher average speeds and experience less fatigue than when using state-of-the-art methods based on footstep frequency, called GUD-WIP.An in-depth user evaluation with twenty participants compared our approach to GUD-WIP on common travel tasks over a range of short, medium and long distances. We measured task performance using four distinct criteria: effectiveness, precision, efficiency and speed. The results show that SAS-WIP is both more efficient and faster than GUD-WIP when walking long distances while being more effective and precise over short distances. When asked their opinion via a post-test questionnaire, participants preferred SAS-WIP to GUD-WIP and reported experiencing less fatigue, having more fun and having a greater level of control when using our approach.","Title: VRRRRoom: Virtual Reality for Radiologists in the Reading Room.\nYear: 2017\n\nAbstract: Reading room conditions such as illumination, ambient light, human factors and display luminance, play an important role on how radiologists analyze and interpret images. Indeed, serious diagnostic errors can appear when observing images through everyday monitors. Typically, these occur whenever professionals are ill-positioned with respect to the display or visualize images under improper light and luminance conditions. In this work, we show that virtual reality can assist radiodiagnostics by considerably diminishing or cancel out the effects of unsuitable ambient conditions. Our approach combines immersive head-mounted displays with interactive surfaces to support professional radiologists in analyzing medical images and formulating diagnostics. We evaluated our prototype with two senior medical doctors and four seasoned radiology fellows. Results indicate that our approach constitutes a viable, flexible, portable and cost-efficient option to traditional radiology reading rooms.","Title: Warping Deixis - Distorting Gestures to Enhance Collaboration.\nYear: 2019\n\nAbstract: When engaged in communication, people often rely on pointing gestures to refer to out-of-reach content. However, observers frequently misinterpret the target of a pointing gesture. Previous research suggests that to perform a pointing gesture, people place the index finger on or close to a line connecting the eye to the referent, while observers interpret pointing gestures by extrapolating the referent using a vector defined by the arm and index finger. In this paper we present Warping Deixis, a novel approach to improving the perception of pointing gestures and facilitate communication in collaborative Extended Reality environments. By warping the virtual representation of the pointing individual, we are able to match the pointing expression to the observer's perception. We evaluated our approach in a co-located side by side virtual reality scenario. Results suggest that our approach is effective in improving the interpretation of pointing gestures in shared virtual environments.","Title: A Survey on 3D Virtual Object Manipulation: From the Desktop to Immersive Virtual Environments.\nYear: 2019\n\nAbstract: Interactions within virtual environments often require manipulating 3D virtual objects. To this end, researchers have endeavoured to find efficient solutions using either traditional input devices or focusing on different input modalities, such as touch and mid-air gestures. Different virtual environments and diverse input modalities present specific issues to control object position, orientation and scaling: traditional mouse input, for example, presents non-trivial challenges because of the need to map between 2D input and 3D actions. While interactive surfaces enable more natural approaches, they still require smart mappings. Mid-air gestures can be exploited to offer natural manipulations mimicking interactions with physical objects. However, these approaches often lack precision and control. All these issues and many others have been addressed in a large body of work. In this article, we survey the state-of-the-art in 3D object manipulation, ranging from traditional desktop approaches to touch and mid-air interfaces, to interact in diverse virtual environments. We propose a new taxonomy to better classify manipulation properties. Using our taxonomy, we discuss the techniques presented in the surveyed literature, highlighting trends, guidelines and open challenges, that can be useful both to future research and to developers of 3D user interfaces."],"string":"[\n \"Title: Foot-turistic multimedia: designing interactive multimedia installations for shoe shops.\\nYear: 2012\\n\\nAbstract: The amount of money spent in a store is positively correlated with the amount of time spent inside. We argue this is an opportunity for multimedia installations that can entertain shoppers and promote interaction with the shop's products. This was the main principle behind our design idea for two interactive installations specifically conceived for shoe shops. We present two applications of interactive multimedia to shoe shopping: an interactive semantic mirror and an interactive window logo. We also describe the results of ethnographic studies, before and after the design process. Our contribution is two-fold: (i) we develop and apply a new multimedia architecture that combines RFID in-store technology with high-end motion detection algorithms, and (ii) we describe one of the first few studies about multimedia installations for improving the shoe shopping experience, in what we call \\\"foot-turistic\\\" interactions.\",\n \"Title: A narrative-based alternative to tagging\\nYear: 2010\\n\\nAbstract: The enormous dissemination of multimedia information over the past few years has led to mechanisms to support its organization, cataloging and search through descriptions or keywords. A popular way of associating such descriptions to content is tagging as can be found in popular sites such as Flickr (for images) or Delicious (bookmarks). This method allows users to associate tags to media, richly describing its content and may help in its retrieval at a later time. However, the process is mostly unstructured, leading to several problems. Nothing guarantees that the tags used are the most appropriate or the same tags are used in similar situations, making retrieval difficult.. Our approach relies on narrative-based interfaces which use stories as an organizing principle for tagging media. Given that humans have used stories to communicate since the dawn of time, narrative is a natural form of interaction. By inter-relating bits of information into a coherent whole, stories convey data in a rich, structured way. A study carried out with 40 users over a period of three months shows that users convey almost six times more information when using narratives to describe their media than what is typical of traditional methods. Furthermore, our pilot study saw narratives increasing tag reuse to 94%. Finally, other problems found in tagging such as synonyms and polysemy were notably absent from story-generated tags\",\n \"Title: Towards accessible touch interfaces\\nYear: 2010\\n\\nAbstract: Touch screen mobile devices bear the promise of endless leisure, communication, and productivity opportunities to motor-impaired people. Indeed, users with residual capacities in their upper extremities could benefit immensely from a device with no demands regarding strength. However, the precision required to effectively select a target without physical cues creates problems to people with limited motor abilities. Our goal is to thoroughly study mobile touch screen interfaces, their characteristics and parameterizations, thus providing the tools for informed interface design for motor-impaired users. We present an evaluation performed with 15 tetraplegic people that allowed us to understand the factors limiting user performance within a comprehensive set of interaction techniques (Tapping, Crossing, Exiting and Directional Gesturing) and parameterizations (Position, Size and Direction). Our results show that for each technique, accuracy and precision vary across different areas of the screen and directions, in a way that is directly dependent on target size. Overall, Tapping was both the preferred technique and among the most effective. This proves that it is possible to design inclusive unified interfaces for motor-impaired and able-bodied users once the correct parameterization or adaptability is assured.\",\n \"Title: Towards content-based retrieval of technical drawings through high-dimensional indexing\\nYear: 2003\\n\\nAbstract: This paper presents a new approach to classify, index and retrieve technical drawings by content. Our work uses spatial relationships, visual elements and high-dimensional indexing mechanisms to retrieve complex drawings from CAD databases. This contrasts with conventional approaches which use mostly textual metadata for the same purpose.\",\n \"Title: A real-time low-cost marker-based multiple camera tracking solution for virtual reality applications\\nYear: 2010\\n\\nAbstract: One of the reasons of how virtual reality applications penetrate industrial production chains slowly is because of significant\\n investment costs to purchase adequate supporting hardware. As a consequence such applications are only available to major\\n companies and fail to benefit the production processes of small and medium enterprises. In this article, we introduce PTrack,\\n a real-time, low-cost, marker-based multiple camera tracking solution for virtual reality providing the accuracy and scalability\\n usually found in much more expensive tracking systems. PTrack is composed of single camera tracking PTrack Units. Each unit\\n is connected to a video camera equipped with infrared strobes and features a novel iterative geometric pose estimation algorithm\\n which does marker-based single camera tracking and is therefore completely autonomous. Multiple PTrack units successively\\n extend the tracking range of the system. For a smooth transition of tracked labels from one camera to another, camera range\\n areas must overlap to form a contiguous tracking space. A PTrack Sensor Fusion Module then computes the pose of a certain\\n label within tracking space and forwards it to interested applications. A universal test setup for optical tracking systems\\n has been built allowing to measure translational and rotational accuracy of PTrack as well as of competing systems.\",\n \"Title: Pen-And-Ink For Blobtree Implicit Models\\nYear: 2005\\n\\nAbstract: New techniques are presented for rendering complex hierarchical skeletal implicit models in several pen-and-ink styles. A particle system is employed to find interesting areas on the surface and perform stroke stylization guided by local shape features. Interesting areas include silhouette strokes and lines following local shape features, such as those caused by CSG junctions. Hidden line removal is performed either by applying a surfel technique for rapid prototyping or more accurately, by using ray tracing. Examples drawn from simple to complex models illustrate the capabilities of our system.\",\n \"Title: Evaluating stories in narrative-based interfaces\\nYear: 2006\\n\\nAbstract: Traditional ways to help users organize and retrieve their documents don't scale well, nor do they properly handle non-textual documents. This paper evaluates narrative-based interfaces as a natural and effective alternative for document retrieval. We have identified what shape document-describing stories take, and what contents to expect. This led to an interface that is able to capture stories, and a knowledge-based infrastructure to understand them. A prototype of the interface was used to validate narrative-based interfaces, with emphasis on story accuracy. To this end, we collected thirty stories whose contents were then compared to the documents they portrayed. Results allow us to conclude that, for the most part, such stories are trustworthy enough to allow humans to retrieve documents reliably (81%-91% of all information is correct). We also confirmed that stories told to a computer are similar to those told to human interviewers.\",\n \"Title: Realfind: managing personal items in the physical world\\nYear: 2008\\n\\nAbstract: While in recent years some effort has been put into helping users manage their personal information in their computers, little has been done to provide meaningful ways to organize and retrieve a user's personal physical objects. Nowadays, technologies such as RFID tags can help bridge the gap between the real and electronic worlds. We propose that a tool that keeps track of the users' objects and seamlessly inter-relates information about them with other relevant autobiographical and contextual data, about the users and their activities, can help manage and retrieve both physical and electronic items in meaningful ways. We describe a prototype tool, RealFind that allows this to take place in a synergistic and effective way. Objects can be searched for based on their properties, but also by relating them to a wide range of contextual information stored on their computers.\",\n \"Title: Indexing High-Dimensional Data for Content-Based Retrieval in Large Databases\\nYear: 2003\\n\\nAbstract: Many indexing approaches for high-dimensional data points have evolved into very complex and hard to code algorithms. Sometimes this complexity is not matched by increase in performance. Motivated by these ideas, we take a step back and look at simpler approaches to indexing multimedia data. In this paper we propose a simple, (not simplistic) yet efficient indexing structure for high-dimensional data Points of variable dimension, using dimension reduction. Our approach maps multidimensional points to a 1D line by computing their Euclidean Norm and use a B/sup +/-Tree to store data points. We exploit B/sup +/-Tree efficient sequential search to develop simple, yet performant methods to implement point, range and nearest-neighbor queries. To evaluate our technique we conducted a set of experiments, using both synthetic and real data. We analyze creation, insertion and query times as a function of data set size and dimension. Results so far show that our simple scheme outperforms current approaches, such as the Pyramid Technique, the A-Tree and the SR-Tree, for many data distributions. Moreover, our approach seems to scale better both with growing dimensionality and data set size, while exhibiting low insertion and search times.\",\n \"Title: Sketch-based retrieval of ClipArt drawings\\nYear: 2004\\n\\nAbstract: These days there are a lot of vector drawings available for people to integrate into documents. These come in a variety of formats, such as Corel, Postscript, CGM, WMF and recently SVG. Typically, such ClipArt drawings tend to be archieved and accessed by categories (e.g. food, shapes, transportation, etc.). However, to find a drawing among hundreds of thousands is not an easy task. While text-driven attempts at classifying image data have been recently supplemented with query-by-image content, these have been developed for bitmap-type data and cannot handle vectorial information. In this paper we present an approach to allow indexing and retrieving vector drawings by content from large datasets. Our prototype can already handle databases with thousands of drawings using commodity hardware. Furthermore, preliminary usability assessments show promising results and suggest good acceptance of sketching as a query mechanism by users.\",\n \"Title: Sketch-based modeling with few strokes\\nYear: 2005\\n\\nAbstract: We present a novel sketch-based system for the interactive modeling of a variety of free-form 3D objects using just a few strokes. Our technique is inspired by the traditional illustration strategy for depicting 3D forms where the basic geometric forms of the subjects are identified, sketched and progressively refined using few key strokes. We introduce two parametric surfaces, rotational and cross sectional blending, that are inspired by this illustration technique. We also describe orthogonal deformation and cross sectional oversketching as editing tools to complement our modeling techniques. Examples with models ranging from cartoon style to botanical illustration demonstrate the capabilities of our system.\",\n \"Title: In search of personal information: narrative-based interfaces\\nYear: 2008\\n\\nAbstract: Most computer users find organizing large amounts of personal information problematic. Often, hierarchies are the sole means to do it. However, users can remember a broader range of autobiographic contextual data about their personal items. Unfortunately, it can seldom be used to manage and retrieve them. Even when this is possible, it is often done by asking users to fill in values for arbitrary properties in dialog boxes or wizards. We propose that narrative-based interfaces can be a natural and effective way to help users recall relevant autobiographic data about their personal items and convey it to the computer. Using Quill, a narrative-based personal document retrieval interface, as a case-study, we show how such an interface can be designed. We demonstrate the approach's validity based on a set of user studies, discussing how the problems raised by the evaluation of such an interface were overcome.\",\n \"Title: Suggestive Contours Over Point-Set Implicits\\nYear: 2008\\n\\nAbstract: This paper presents a system that combines large point-set implicit surfaces with fast line-based rendering. We devised a new process for extracting suggestive contours quickly by using particles scattered throughout the surface to identify areas of interest, followed by clustering and line-fitting. Furthermore, we improve on state-of-the-art methods for extracting silhouettes and feature-lines by harness-ing the descriptive power of the surface representation. This provides heuristics for fast determination of curvature and allows for the local regeneration of shape-depicting line elements after editing operations. While visual examples illustrate the high quality of the drawings obtained with our application, as well as the high detail it can provide for more complex models, run-times show comparatively higher performance over similar approaches for the same number of points.\",\n \"Title: Telling Stories with Dialogue Boxes to Retrieve Documents\\nYear: 2004\\n\\nAbstract: Nowadays, it is common for users to handle large numbers of documents. Organizing and retrieving those documents is extremely difficult using the tools commonly provided for those tasks. The use of document-describing narratives constitutes an alternate, easier way of allowing the users to do so. Narratives can help them remember important information about documents and are a natural way to convey that information to computers. In order to develop this approach, it is necessary to understand what shape do document-describing stories have. To this end we interviewed 20 users and collected 60 stories about documents. Analyzing these stories yielded a thorough characterization of their contents and structure and to extract guidelines on how to deal with them. We then validated those results by creating and evaluating two lowFidelity prototypes for possible story-capturing interfaces. We found that stories told to computers can be very similar to those told to humans, if the interface is properly designed. These results seem to suggest that structured text entry is a promising design for this interface.\",\n \"Title: CGEMS: Computer Graphics Educational Materials Server\\nYear: 2003\\n\\nAbstract: Computer graphics has evolved considerably over the past few decades. As computer science, digital arts, and other areas of study that use computer graphics continue to evolve and gain new substance, educators have come to master new content and achieve deeper understandings of computers and imagery. As the core field becomes more mature, educators in all computer graphics disciplines have a greater need for high-quality curricular resources. Offering excellent educational materials is an important service to the community of educators. Such support will empower both young and seasoned educators alike to benefit from and contribute to the work of others. In this way, we can achieve a higher standard of teaching worldwide.The purpose of our work is to provide tools to foster such a community of computer graphics educators. We will present a system that will act as the means for their work to be appraised, assessed and made available to others through an online server for refereed educational content in computer graphics.In this paper we describe the basis for and highlight some of the starting requirements of CGEMS, the online Computer Graphics Educational Materials Server. This is organized around a web-based groupware application that supports the submission, review, acquisition, and archiving of curricular resources.\",\n \"Title: Content-Based Retrieval Of Technical Drawings\\nYear: 2005\\n\\nAbstract: This paper presents a new approach to classify, index and retrieve technical drawings by content. Our work uses spatial relationships, shape geometry and high-dimensional indexing mechanisms to retrieve complex drawings from CAD databases. This contrasts with conventional approaches which use mostly textual metadata. Creative designers and draftspeople often re-use data from previous projects, publications and libraries of ready-to-use components. Usually, retrieving these drawings is a slow, complex and error-prone endeavour. Unfortunately, the widespread use of CAD systems, while making it easier to create drawings, exacerbates this problem, insofar as the number of projects grows enormously, without providing adequate searching mechanisms to support retrieving these documents. We describe an approach that supports automatic indexation of technical drawing databases through drawing simplification, feature extraction and efficient algorithms to index large amounts of data. We describe in detail our classification process and present results from usability tests on our prototype.\",\n \"Title: IMMIView: a multi-user solution for design review in real-time\\nYear: 2010\\n\\nAbstract: IMMIView is an interactive system that relies on multiple modalities and multi-user interaction to support collaborative design\\n review. It was designed to offer natural interaction in visualization setups such as large-scale displays, head mounted displays\\n or TabletPC computers. To support architectural design, our system provides content creation and manipulation, 3D scene navigation\\n and annotations. Users can interact with the system using laser pointers, speech commands, body gestures and mobile devices.\\n In this paper, we describe how we design a system to answer architectural user requirements. In particular, our system takes\\n advantage of multiple modalities to provide a natural interaction for design review. We also propose a new graphical user\\n interface adapted to architectural user tasks, such as navigation or annotations. The interface relies on a novel stroke-based\\n interaction supported by simple laser pointers as input devices for large-scale displays. Furthermore, input devices such\\n as speech and body tracking allow IMMIView to support multiple users. Moreover, they allow each user to select different modalities\\n according to their preference and modality adequacy for the user task. We present a multi-modal fusion system developed to\\n support multi-modal commands on a collaborative, co-located, environment, i.e. with two or more users interacting at the same\\n time, on the same system. The multi-modal fusion system listens to inputs from all the IMMIView modules in order to model\\n user actions and issue commands. The multiple modalities are fused based on a simple rule-based sub-module developed in IMMIView\\n and presented in this paper. User evaluation performed over IMMIView is presented. The results show that users feel comfortable\\n with the system and suggest that users prefer the multi-modal approach to more conventional interactions, such as mouse and\\n menus, for the architectural tasks presented.\",\n \"Title: Towards Calligraphic Interfaces: Sketching 3D Scenes with Gestures and Context Icons\\nYear: 2000\\n\\nAbstract: GIDeS (Gesture-based Intuitive Design System) is a gesture-based modeling system that addresses theknown ergonomic shortcomings of present-day CAD systems for conceptual shape design. GIDeS uses atablet and stylus combination to combine the intuitive appeal of gesture-based interfaces with contextbasedicons. GIDeS draws on previous modeling work, using contextual information and feedback to freeusers from remembering detailed modeling gestures, allowing them to concentrate on drawing,...\",\n \"Title: Quill: a narrative-based interface for personal document retrieval\\nYear: 2006\\n\\nAbstract: The ways to manage and retrieve documents have changed little in recent years. Browsing is increasingly unpractical and search still is fairly simple, relying mostly on keywords. The wide range of autobiographic information that users remember about their documents cannot be used. We present a new interaction paradigm, narrative-based interfaces, especially well suited for document retrieval. Stories make remembering information easier since it appears contextualized in a coherent whole. We describe the Quill system, a narrative-based query-formulation interface for personal document retrieval, explaining the user studies and results that led to its design in a sound and effective way. Its evaluation confirms that stories can be told naturally, containing the desired information about documents.\",\n \"Title: Online parsing of visual languages using adjacency grammars\\nYear: 1995\\n\\nAbstract: Visual computing environments continue to grow in importance, yet fast, general parsing algorithms for visual languages remain elusive. In this paper, we present an incremental parsing algorithm for a broad class of visual languages which do not contain overlapping elements. Our algorithm is based on the concept of adjacency grammars, where adjacencies are defined so as to encompass both spatial and logical constraints. Our approach combines bottom-up and top-down methods to support incremental parsing of visual input, allowing for measurably efficient online parsing of diagram-like visual languages, with observed linear run-times for large visual sentences.\",\n \"Title: Combining bimanual manipulation and pen-based input for 3D modelling\\nYear: 2011\\n\\nAbstract: Multitouch enabled surfaces can bring advantages to modelling scenarios, in particular if bimanual and pen input can be combined. In this work, we assess the suitability of multitouch interfaces to 3D sketching tasks. We developed a multitouch enabled version of ShapeShop, whereby bimanual gestures allow users to explore the canvas through camera operations while using a pen to sketch. This provides a comfortable setting familiar to most users. Our contribution focuses on comparing the combined approach (bimanual and pen) to the pen-only interface for similar tasks. We conducted the evaluation helped by ten sketching experts who exercised both techniques. Results show that our approach both simplifies workflow and lowers task times, when compared to the pen-only interface, which is what most current sketching applications provide.\",\n \"Title: Generic shape classification for retrieval\\nYear: 2005\\n\\nAbstract: We present a shape classification technique for structural content–based retrieval of two-dimensional vector drawings. Our method has two distinguishing features. For one, it relies on explicit hierarchical descriptions of drawing structure by means of spatial relationships and shape characterization. However, unlike other approaches which attempt rigid shape classification, our method relies on estimating the likeness of a given shape to a restricted set of simple forms. It yields for a given shape, a feature vector describing its geometric properties, which is invariant to scale, rotation and translation. This provides the advantage of being able to characterize arbitrary two–dimensional shapes with few restrictions. Moreover, our technique seemingly works well when compared to established methods for two dimensional shapes.\",\n \"Title: Agrafo: a visual interface for grouping and browsing digital photos\\nYear: 2008\\n\\nAbstract: With the growing popularity of digital cameras, the organization, browsing, management and grouping of photos become a problem of every photograph (professional or amateur), because their collections easily achieve the order of thousands. Here, we present a system to automate these processes, which relies on photo information, such as, semantic features (extracted from content), meta-information and low level.\",\n \"Title: Mnemonical Body Shortcuts for Interacting with Mobile Devices\\nYear: 2007\\n\\nAbstract: Mobile devices’ user interfaces have some similarities with the traditional interfaces offered by desktop computers, which\\n are highly problematic when used in mobile contexts. Gesture recognition in mobile interaction appears as an important area\\n to provide suitable on-the-move usability. We present a body space based approach to improve mobile device interaction and\\n on the move performance. The human body is presented as a rich repository of meaningful relations which are always available\\n to interact with. Body-based gestures allow the user to naturally interact with mobile devices with no movement limitations.\\n Preliminary studies using RFID technology were performed, validating the mnemonical body shortcuts concept as a new mobile\\n interaction mechanism. Finally, inertial sensing prototypes were developed and evaluated, proving to be suitable for mobile\\n interaction and efficient, accomplishing a good recognition rate.\",\n \"Title: Mockup Builder: 3D modeling on and above the surface.\\nYear: 2013\\n\\nAbstract: We present Mockup Builder, a semi-immersive environment for conceptual design which allows virtual mockups to be created using gestures. Our goal is to provide familiar ways for people to conceive, create and manipulate three-dimensional shapes. To this end, we developed on-and-above-the-surface interaction techniques based on asymmetric bimanual interaction for creating and editing 3D models in a stereoscopic environment. Our approach combines both hand and finger tracking in the space on and above a multi-touch surface. This combination brings forth an alternative design environment where users can seamlessly switch between interacting on the surface or above it to leverage the benefit of both interaction spaces. A formal user evaluation conducted with experienced users shows very promising avenues for further work towards providing an alternative to current user interfaces for modeling.\",\n \"Title: Modeling plant structures using concept sketches\\nYear: 2006\\n\\nAbstract: Creating 3D plant models is often a hard and laborious task. To make it easier and more natural, we propose a sketch-based interface for modeling single-compound plant structures with phyllotactic arrangements. Our approach is based on the traditional illustration technique of concept sketching. The user sketches the key construction lines for the main plant body and lateral organs. Our system then automatically constructs the 3D plant arrangement in phyllotactic patterns rendered as pen-and-ink line drawings. The user is then able to edit the model by oversketching the construction lines, adjusting density of lateral organs, and specifying different phyllotactic patterns. We demonstrate the capabilities of our system for a variety of plant models.\",\n \"Title: NavTap: a long term study with excluded blind users\\nYear: 2009\\n\\nAbstract: NavTap is a navigational method that enables blind users to input text in a mobile device by reducing the associated cognitive load. In this paper, we present studies that go beyond a laboratorial setting, exploring the methods' effectiveness and learnability as well as its influence on the users' daily lives. Eight blind users participated in designing the prototype (3 weeks) while five took part in the studies along 16 more weeks. Results gathered in controlled weekly sessions and real life usage logs enabled us to better understand NavTap's advantages and limitations. The method revealed itself both as easy to learn and improve. Indeed, users were able to better control their mobile devices to send SMS and use other tasks that require text input such as managing a phonebook, from day one, in real-life settings. While individual user profiles play an important role in determining their evolution, even less capable users (with age-induced impairments or cognitive difficulties), were able to perform the assigned tasks (sms, directory) both in the laboratory and in everyday use, showing continuous improvement to their skills. According to interviews, none were able to input text before. Nav-Tap dramatically changed their relation with mobile devices and noticeably improved their social interaction capabilities.\",\n \"Title: A comparison of ray pointing techniques for very large displays\\nYear: 2010\\n\\nAbstract: Ray-pointing techniques are often advocated as a way for people to interact with very large displays from several meters away. We are interested in two factors that can affect ray pointing: the particular technique's control type, and parallax. Consequently, we tested four ray pointing variants on a wall display that covers a large part of the user's field of view. Tasks included horizontal and vertical targeting, and tracing. Our results show that (a) techniques based on 'rotational control' perform better for targeting tasks, and (b) techniques with low parallax are best for tracing tasks. We also show that a Fitts's law analysis based on angles (as opposed to linear distances) better approximates people's ray pointing performance.\",\n \"Title: Non-photorealistic rendering in context: an observational study\\nYear: 2006\\n\\nAbstract: Pen-and-ink line drawing techniques are frequently used to depict form, tone, and texture in artistic, technical, and scientific illustration. In non-photorealistic rendering (NPR), considerable progress has been made towards reproducing traditional pen-and-ink techniques for rendering 3D objects. However, formal evaluation and validation of these NPR images remain an important open research problem. In this paper we present an observational study with three groups of users to examine their understanding and assessment of hand-drawn pen-and-ink illustrations of objects in comparison with NPR renditions of the same 3D objects. The results show that people perceive differences between those two types of illustration but that those that look computer-generated are still highly valued as scientific illustrations.\",\n \"Title: Retrieving Vector Graphics Using Sketches\\nYear: 2004\\n\\nAbstract: In this paper we present an approach to allow indexing and retrieving vector graphics by content, using topological and geometric information automatically extracted from figures. The method described retrieves WMF ClipArt files as an instance of the general problem of searching vector drawings. Our prototype can already handle databases with thousands of drawings using commodity hardware. Our scheme uses pattern recognition to identify shapes ensuring good precision vs recall trade-offs, when compared to other approaches. Preliminary usability assessments show promising results and suggest good acceptance of sketching as a query mechanism by users.\",\n \"Title: Adaptive tools for the elderly: new devices to cope with age-induced cognitive disabilities\\nYear: 2001\\n\\nAbstract: We look at the issues and methodologies needed to develop, deploy, and evaluate situation-aware mobile computing devices that adapt to the needs of elder users based on observed or predicted user behavior and needs. This paper discusses how pervasive computing can help the aging population live independently for as long as possible. We believe that successfully applying technology to this problem will require careful studies of how the target population actually lives and what their actual needs are. We propose a combination of traditional laboratory studies and surveys, as well as the use of instrumented spaces and personal monitoring devices to measure how people behave, normally and while using proposed assistive devices. A key requirement is the development of ways to simultaneously monitor signals from the body, activities, and social interactions to provide a more complete view of individuals and their lives. Some of the core research issues are machine learning to design devices learn from and adapt to user behavior, user-computer interaction to build devices and systems that support users in their tasks, mobile computing to support user and device mobility, mobility and data management to represent, access, update, and protect information, sensing devices that monitor human activity and finally rapid prototyping of services in a sensor-rich environment, in a scalable and secure manner.\",\n \"Title: Motivation To E-Learn Within Organizational Settings: An Exploratory Factor Structuret\\nYear: 2006\\n\\nAbstract: E-learning is expected to support organizations and individuals so they can become more adaptable and competitive. However, in order for organizations to realize the full potential of this technology, they should create and sustain the right context to foster learning in articulation with business objectives. This requires active participation and engagement of workers. This work explores a variable called motivation-to-e-learn, a key component of this process. Our goal is to identify what motivation-related variables are critical for users engagements in the process. To this end, we explored the importance of a set of motivation-to-e-learn variables for a group of participants at our university. From this activity, an exploratory four-factor structure emerged that explains 67% of motivation to e-learn variance. We discuss our results, together with their implications for designing technology-supported learning experiences, lessons learned, and future work. Our contribution is a step toward integrating business processes, learners, and e-learning systems into an effective and harmonious whole.\",\n \"Title: Thesaurus-based 3D Object Retrieval with Part-in-Whole Matching\\nYear: 2010\\n\\nAbstract: Research in content-based 3D retrieval has already started, and several approaches have been proposed which use in different manner a similarity assessment to match the shape of the query against the shape of the objects in the database. However, the success of these solutions are far from the success obtained by their textual counterparts.A major drawback of most existing 3D retrieval solutions is their inability to support partial queries, that is, a query which does not need to be formulated by specifying a whole query shape, but just a part of it, for example a detail of its overall shape, just like documents are retrieved by specifying words and not whole texts. Recently, researchers have focused their investigation on 3D retrieval which is solved by partial shape matching. However, at the extent of our knowledge, there is still no 3D search engine that provides an indexing of the 3D models based on all the interesting subparts of the models.In this paper we present a novel approach to 3D shape retrieval that uses a collection-aware shape decomposition combined with a shape thesaurus and inverted indexes to describe and retrieve 3D models using part-in-whole matching. The proposed method clusters similar segments obtained trough a multilevel decomposition of models, constructing from such partition the shape thesaurus. Then, to retrieve a model containing a sub-part similar to a given query, instead of looking on a large set of subparts or executing partial matching between the query and all models in the collection, we just perform a fast global matching between the query and the few entries in the thesaurus. With this technique we overcame the time complexity problems associated with partial queries in large collections.\",\n \"Title: Representing and Parsing Sketched Symbols Using Adjacency Grammars and a Grid-Directed Parser\\nYear: 2007\\n\\nAbstract: While much work has been done in Structural and Syntactical Pattern Recognition applied to drawings, most approaches are non-interactive. However, the recent emergence of viable pen-computers makes it desirable to handle pen-input such as sketches and drawings interactively. This paper presents a syntax-directed approach to parse sketches based on Relational Adjacency Grammars, which describe spatial and topological relations among parts of a sketch. Our approach uses a 2D grid to avoid re-scanning all the previous input whenever new strokes entered into the system, thus speeding up parsing considerably. To evaluate the performance of our approach we have tested the system using non-trivial inputs analyzed with two different grammars, one to design user interfaces and the other to describe floor-plans. The results clearly show the effectiveness of our approach and demonstrate good scalability to larger drawings.\",\n \"Title: The continuous interaction space: interaction techniques unifying touch and gesture on and above a digital surface\\nYear: 2011\\n\\nAbstract: The rising popularity of digital table surfaces has spawned considerable interest in new interaction techniques. Most interactions fall into one of two modalities: 1) direct touch and multi-touch (by hand and by tangibles) directly on the surface, and 2) hand gestures above the surface. The limitation is that these two modalities ignore the rich interaction space between them. To move beyond this limitation, we first contribute a unification of these discrete interaction modalities called the continuous interaction space. The idea is that many interaction techniques can be developed that go beyond these two modalities, where they can leverage the space between them. That is, we believe that the underlying system should treat the space on and above the surface as a continuum, where a person can use touch, gestures, and tangibles anywhere in the space and naturally move between them. Our second contribution illustrates this, where we introduce a variety of interaction categories that exploit the space between these modalities. For example, with our Extended Continuous Gestures category, a person can start an interaction with a direct touch and drag, then naturally lift off the surface and continue their drag with a hand gesture over the surface. For each interaction category, we implement an example (or use prior work) that illustrates how that technique can be applied. In summary, our primary contribution is to broaden the design space of interaction techniques for digital surfaces, where we populate the continuous interaction space both with concepts and examples that emerge from considering this space as a continuum.\",\n \"Title: PC Clusters for Virtual Reality\\nYear: 2008\\n\\nAbstract: In the late 90's the emergence of high performance 3D commodity graphics cards opened the way to use PC clusters for high perfor- mance Virtual Reality (VR) applications. Today PC clusters are broadly used to drive multi projector immersive environments. In this paper, we survey the different approaches that have been developed to use PC clusters for VR applications. We review the most common software tools that enable to take advantage of the power of clusters. We also discuss some new trends.\",\n \"Title: Web-Based Support For Resource-Effective E-Learning\\nYear: 2006\\n\\nAbstract: This article presents work done at the Technical University of Lisbon, on web systems to support technology-enhanced learning. Based on eighteen months experience with webcast technologies and commonly used Learning Management Systems, this work has integrated both concepts and developed a simple, yet effective learning approach. This approach supports both students and professors in moving from the traditional classroom to technology-enhanced online settings. We present the evolution of our system and the results obtained from testing and evaluating the prototype, during the last Spring semester. One of the major features of our approach lies in combining both online and offline components of the e-Learning experience and incorporating desirable traits from traditional and technology-mediated learning. This way, we have identified significant issues for users in order to better manage the changes required to adapt our system to organizational processes and context of use. Our assessment points to changes in the teaching method, course organization, and highlights new factors of students' motivation. Results, however preliminary, seem to indicate both the usefulness of our approach and the feasibility of deploying e-learning initiatives with efforts optimization to complement traditional offerings in university settings.\",\n \"Title: A comparative study of interaction metaphors for large-scale displays\\nYear: 2009\\n\\nAbstract: Large-scale displays require new interaction techniques because of their physical size. There are technologies that tackle the problem of interaction with such devices by providing natural interaction to larger surfaces. We argue, however, that large-scale displays offer physical freedom that is not yet being applied to interaction. To better understand how distance affects user interaction, we present a comparative study of interaction metaphors for large-scale displays. We present three metaphors: Grab, Point and Mouse. The metaphors were included in our tests as we felt that each would be more suited to a specific distance: this is the focus of our tests. We then asked the users to solve a puzzle using those metaphors from different distances. We discovered that the point metaphor achieves better results on all tests. However, there is evidence that grab and mouse remain valid for specific tasks.\",\n \"Title: Describing documents: what can users tell us?\\nYear: 2004\\n\\nAbstract: With the increasing number of computers per user, it has become common for most users to deal with growing numbers of electronic documents. Those documents are usually stored in hierarchic file systems, requiring them to be classified into the hierarchy, a difficult task. Such organization schemes do not provide adequate support for the efficient and effortless retrieval of documents at a later time, since their position in the hierarchy is one of the only clues to a document's whereabouts. However, humans are natural-born storytellers, and stories help relate and remember important pieces of information. Hence, the usage of narratives where a user \\\"tells a story\\\" about the document will be a valuable tool towards simplifying the retrieval task.To find out if there are common patterns in stories about documents, we performed a study where 60 such stories were collected and analyzed. We identified the most common story elements (time, storage and purpose) and how they are likely to relate in typical stories. This preliminary study suggests that it is possible to infer archetypical stories. Further, we present a set of guidelines for the design of narrative-based document retrieval interfaces.\",\n \"Title: Mockup builder: direct 3D modeling on and above the surface in a continuous interaction space\\nYear: 2012\\n\\nAbstract: Our work introduces a semi-immersive environment for conceptual design where virtual mockups are obtained from gestures we aim to get closer to the way people conceive, create and manipulate three-dimensional shapes. We present on-and-above-the-surface interaction techniques following Guiard's asymmetric bimanual model to take advantage of the continuous interaction space for creating and editing 3D models in a stereoscopic environment. To allow for more expressive interactions, our approach continuously combines hand and finger tracking in the space above the table with multi-touch on its surface. This combination brings forth an alternative design environment where users can seamlessly switch between interacting on the surface or in the space above it depending on the task. Our approach integrates continuous space usage with bimanual interaction to provide an expressive set of 3D modeling operations. Preliminary trials with our experimental setup show this as a very promising avenue for further work.\",\n \"Title: \\\"When i'm sixty-four...\\\": are there real strategies for providing universal accessibility for the elderly\\nYear: 2002\\n\\nAbstract: In this panel we will present four strategies for providing computing for the elderly. We hope to generate discussion and ideas of the plusses and minuses of these strategies.\",\n \"Title: Sketch-based retrieval of complex drawings using hierarchical topology and geometry\\nYear: 2009\\n\\nAbstract: Due to the proliferation of drafting packages, there are a lot of vector drawings available for people to integrate into documents. Moreover, creative designers and drafts-people often reuse data from previous projects and libraries of ready-to-use components. Usually, retrieving these drawings is a slow, complex and error-prone endeavor. While text-driven attempts at classifying image data have been recently supplemented with query-by-image content, these work only for bitmap-type data and cannot handle vectorial information. Furthermore, they are not very good at retrieving partial information, which makes it difficult to search complex documents. Here we present a new approach to allow efficient retrieval of complex vector drawings by content using simple sketches as queries. Our work uses a new hierarchical topology description mechanism, which allows comparing complex drawings to simple queries. In particular, we produce a multilevel description of drawings, from the topology graph, using different levels of detail and subparts of the information. We also show that the graph spectrum is stable and reliable for use as a topology description. Finally, experimental tests show that our approach is good at retrieving complex drawings from two different application domains, CAD and clip-art figures.\",\n \"Title: Telling stories to computers for document retrieval\\nYear: 2004\\n\\nAbstract: The documents users must handle are growing both in number and diversity. However, the ways of organizing and retrieving them remain largely unchanged. Given the innate human ability to tell stories, the use of narratives can be a natural and effective way to retrieve documents. To better understand how narratives can be used in this context, a thorough characterization of their contents and structure was obtained from several interviews. Then, the results were validated by the evaluation of low fidelity prototypes for story-capture interfaces, allowing us to verify that stories are valid as document-retrieval tools, and the shape those interfaces should take (structured text entry).\",\n \"Title: Understanding Individual Differences: Towards Effective Mobile Interface Design and Adaptation for the Blind.\\nYear: 2014\\n\\nAbstract: No two people are alike. We usually ignore this diversity as we have the capability to adapt and, without noticing, become experts in interfaces that were probably misadjusted to begin with. This adaptation is not always at the user's reach. One neglected group is the blind. Spatial ability, memory, and tactile sensitivity are some characteristics that diverge between users. Regardless, all are presented with the same methods ignoring their capabilities and needs. Interaction with mobile devices is highly visually demanding which widens the gap between blind people. Our research goal is to identify the individual attributes that influence mobile interaction, considering the blind, and match them with mobile interaction modalities in a comprehensive and extensible design space. We aim to provide knowledge both for device design, device prescription and interface adaptation.\",\n \"Title: Using autobiographic information to retrieve real and electronic documents\\nYear: 2007\\n\\nAbstract: Current systems force users to store their documents in hierarchic filesystems. However, users remember their documents not in terms of ad-hoc categories, but of their contents, why they were written, etc. Describing documents using such autobiographic information would be a simpler and more effective way for users to retrieve them. Furthermore, we found that users mention printed versions of documents when retrieving them. However, current systems don't regard the printed and electronic versions of a document as facets of the same entity. To solve these problems we developed an interface that allows users to browse their autobiographic information, gathered by a special-purpose monitoring subsystem, to retrieve their documents. We bridged the gap between the real and electronic worlds by maintaining the association between paper and electronic documents resorting to RFID technology. Tests show our interface allows users to efficiently retrieve their documents.\",\n \"Title: Evaluating adaptive user profiles for news classification\\nYear: 2004\\n\\nAbstract: Never before have so many information sources been available. Most are accessible on-line and some exist on the Internet alone. However, this large information quantity makes interesting articles hard to find. Modern Personal Digital Assistants (PDAs), mobile phones, and the advent of ubiquitous computing will further complicate matters. Away from the desktop, the time to select important articles might be even harder to find. Strategies to select relevant information are sorely needed.One such strategy is content-based filtering, coupled with User Profiles. Our prototype uses a Bayesian classifier to select articles of interest to a specific user, according to his profile. The articles are extracted from web pages and displayed in a zoomable interface-based browser on a PDA. Interests may change over time, making it important to keep the profile up to date. The system monitors the users' reading behaviors, from which it infers their interest in particular articles and updates the profile accordingly. Results show that, from the start, most articles are correctly classified. An initial profile opposite to the user's actual interests can be reversed in less than ten days, showing the robustness of our approach. A user's interest in an article is inferred with a high degree of accuracy (over 90%).\",\n \"Title: Understanding Stories about Personal Documents\\nYear: 2008\\n\\nAbstract: Hierarchies are the most common way to help users organize their personal information. However, their use is fraught with problems. In particular, the users' documents, stored in the filesystem, are notoriously difficult to manage and retrieve. A way to alleviate those problems is to resort to a wide range of knowledge about the users, their actions and the world that surrounds them. Systems that have done so lack an organizing principle that helps users refer to all the information that might be relevant. We propose a novel user interface paradigm, narrative-based interfaces, that provides such an organizing principle, showing how knowledge plays a central role in understanding the users' stories. An analysis of Quill, a prototype narrative-based interface for personal document retrieval, will show how narratives can successfully be used to help users retrieve their documents.\",\n \"Title: An haptic-based immersive environment for shape analysis and modelling\\nYear: 2010\\n\\nAbstract: Currently, the design of aesthetic products is a process that requires a set of activities where digital models and physical mockups play a key role. Typically, these are modified (and built) several times before reaching the desired design, increasing the development time and, consequently, the final product cost. In this paper, we present an innovative design environment for computer-aided design (CAD) surface analysis. Our system relies on a direct visuo-haptic display system, which enables users to visualize models using a stereoscopic view, and allows the evaluation of sectional curves using touch. Profile curves are rendered using an haptic device that deforms a plastic strip, thanks to a set of actuators, to reproduce the curvature of the shape co-located with the virtual model. By touching the strip, users are able to evaluate shape characteristics, such as curvature or discontinuities (rendered using sound), and to assess the surface quality. We believe that future computer-aided systems (CAS)/CAD systems based on our approach will contribute in improving the design process at industrial level. Moreover, these will allow companies to reduce the product development time by reducing the number of physical mockups necessary for the product design evaluation and by increasing the quality of the final product, allowing a wider exploration and comparative evaluation of alternatives in the given time.\",\n \"Title: Graphical Modeling and Calligraphic Interfaces\\nYear: 2007\\n\\nAbstract: Summary form only given. CAD systems now enable us to manufacture complicated models. However, computers have yet to become usable at the very early stages of product design, where pencil and paper still reign. This is because present-day systems, with their focus on internal representation and dialogue hierarchies, require designers to leap large conceptual gaps when evolving from their idea of a desired object to the geometric model that formally expresses its intended shape. As computers become more sophisticated and powerful, alternative input modalities and interface techniques are emerging which form the basis for a new generation of sketching applications supporting what we call Calligraphic interfaces, where artificial dialogue constraints imposed by the previous generation of UIs are removed. We are exploring with minimalist approaches and techniques to approximate traditional methods including modeling, illustration and retrieval. I will talk about our research and ongoing projects at the Technical University of Lisbon, towards this goal.\",\n \"Title: Sketch-based modeling: A survey\\nYear: 2009\\n\\nAbstract: User interfaces in modeling have traditionally followed the WIMP (Window, Icon, Menu, Pointer) paradigm. Though functional and very powerful, they can also be cumbersome and daunting to a novice user, and creating a complex model requires considerable expertise and effort. A recent trend is toward more accessible and natural interfaces, which has lead to sketch-based interfaces for modeling (SBIM). The goal is to allow sketches—hasty freehand drawings—to be used in the modeling process, from rough model creation through to fine detail construction. Mapping a 2D sketch to a 3D modeling operation is a difficult task, rife with ambiguity. To wit, we present a categorization based on how a SBIM application chooses to interpret a sketch, of which there are three primary methods: to create a 3D model, to add details to an existing model, or to deform and manipulate a model. Additionally, in this paper we introduce a survey of sketch-based interfaces focused on 3D geometric modeling applications. The canonical and recent works are presented and classified, including techniques for sketch acquisition, filtering, and interpretation. The survey also provides an overview of some specific applications of SBIM and a discussion of important challenges and open problems for researchers to tackle in the coming years.\",\n \"Title: A Simple Approach to Recognise Geometric Shapes Interactively\\nYear: 1999\\n\\nAbstract: This paper presents a simple method to recognise multistroke sketches of geometric shapes. It uses temporal adjacency and global geometric properties of figures to recognise a simple vocabulary of geometric shapes including solid and dashed line styles, selection and delete gestures. The geometric features used (convex hull, smallest-area regular polygons, perimeter and area scalar ratios) are invariant with rotation and scale of figures. We have found the method very usable with acceptable recognition rates although the multi-stroke approach poses problems in choosing appropriate values for time-outs. Although we have privileged simplicity over robustness, the method has proved suitable for interactive applications.\",\n \"Title: Conceptual Design And Prototyping To Explore Creativity\\nYear: 2007\\n\\nAbstract: Many approaches to teaching HCI focus on either user requirements or prototyping. However, these two techniques do not provide enough tools for Students to explore the design space in breadth at early stages of conception. Indeed, even when these two approaches are combined, students still lack tools to explore the design space and bridge the gap from requirements to prototyping. In this paper, we describe the way we teach Human Computer Interaction, stimulating students to be creative during interface design. To that end we added course materials on conceptual design and scenario based interaction, combined with the exploration of different low fidelity prototypes, which we believe increase both the usability of student-developed prototypes and foster learner creativity. To illustrate this we present some of the best examples of interactive prototypes designed and developed by Students attending our HCI Course in the context of Information Systems and Computer Engineering (ISCE) curriculum at the Technical University of Lisbon, Portugal. While the current approach seems to elicit positive responses and draw encouraging remarks from Students, work remains to be done in emerging interface paradigms and more formal evaluation on how this approach positively affects student outcomes.\",\n \"Title: Title of tutorial: Designing immersive VR systems: From bits to bolts\\nYear: 2012\\n\\nAbstract: Immersive 3D Virtual Environments (VE) have become affordable for many research centers. However, a complete solution needs several integration steps to be fully operational. Some of these steps are difficult to accomplish and require an uncommon combination of different skills. This tutorial presents the most recent techniques developed to address this problem, from displays to software tools. The hardware in a typical VR installations combines projectors, screens, speakers, computers, tracking and I/O devices. The tutorial will discuss hardware options, explaining their advantages and disadvantages. We will cover design decisions from basic software and hardware design, through user tracking, multimodal human-computer interfaces and acoustic rendering, to how to administrate the whole solution. Additionally, we will provide an introduction to existing tracking technologies, explaining how the most common devices work, while focusing on infrared optical tracking. Finally, we briefly cover integration software and middleware developed for most VE settings.\",\n \"Title: Title of tutorial: Designing immersive VR systems: From bits to bolts\\nYear: 2012\\n\\nAbstract: Immersive 3D Virtual Environments (VE) have become affordable for many research centers. However, a complete solution needs several integration steps to be fully operational. Some of these steps are difficult to accomplish and require an uncommon combination of different skills. This tutorial presents the most recent techniques developed to address this problem, from displays to software tools. The hardware in a typical VR installations combines projectors, screens, speakers, computers, tracking and I/O devices. The tutorial will discuss hardware options, explaining their advantages and disadvantages. We will cover design decisions from basic software and hardware design, through user tracking, multimodal human-computer interfaces and acoustic rendering, to how to administrate the whole solution. Additionally, we will provide an introduction to existing tracking technologies, explaining how the most common devices work, while focusing on infrared optical tracking. Finally, we briefly cover integration software and middleware developed for most VE settings.\",\n \"Title: Augmenting touch interaction through acoustic sensing\\nYear: 2011\\n\\nAbstract: Recognizing how a person actually touches a surface has generated a strong interest within the interactive surfaces community. Although we agree that touch is the main source of information, unless other cues are accounted for, user intention might not be accurately recognized. We propose to expand the expressiveness of touch interfaces by augmenting touch with acoustic sensing. In our vision, users can naturally express different actions by touching the surface with different body parts, such as fingers, knuckles, fingernails, punches, and so forth - not always distinguishable by touch technologies but recognized by acoustic sensing. Our contribution is the integration of touch and sound to expand the input language of surface interaction.\",\n \"Title: Handling Ambiguity and Errors: Visual Languages for Calligraphic Interaction\\nYear: 2001\\n\\nAbstract: This paper describes error handling and ambiguity in a class of applications organized around drawing and sketching, which we call Calligraphic Interfaces.While errors and imprecision are unavoidable features of human input, these have long been considered nuisances and problems to circumvent in user interface design.However, the transition away from non-WIMP interface styles and into continuous media featuring recognition requires that we take a fresh approach to errors and imprecision.We present new tools and interaction styles to allow designers to develop error tolerant and simpler interaction dialogues.\",\n \"Title: From Tapping to Touching: Making Touch Screens Accessible to Blind Users\\nYear: 2008\\n\\nAbstract: The NavTouch navigational method enables blind users to input text in a touch-screen device by performing directional gestures to navigate a vowel-indexed alphabet.\",\n \"Title: InStory: a system for mobile information access, storytelling and gaming activities in physical spaces\\nYear: 2005\\n\\nAbstract: This paper describes the work carried out in the InStory project. InStory has the goal of defining and implementing a platform for mobile storytelling, information access, and gaming activities. The platform has a flexible computational architecture that integrates heterogeneous devices, different media formats and computational support for different narrative modes and gaming activities. The system is driven and validated by a set of story threads and narratives that are centered on the exploration of physical spaces. This exploration is combined with the perspective of sharing information between users and providing historic context. The project also wants to explore the social aspect of shared narratives and activities, with the idea that the technology can provide new innovative approaches to social participation in different types of events.\",\n \"Title: Interactive installations: tales from the trenches\\nYear: 2011\\n\\nAbstract: Breakthrough innovation can be interpreted as research translated into products that the market accepts. The process of market translation of several products developed by WowSystems, a Portuguese company specialized in novel interaction paradigms, is explained in this paper as a case study shedding some light into how innovation centers can better promote innovation, in the form of well-succeeded products. We describe two paradigmatic \\\"tales from the trenches\\\" and conclude with some guidelines that were outlined on the basis of more than three years delivering fifty interactive installations.\",\n \"Title: EC/NSF workshop on universal accessibility of ubiquitous computing: providing for the elderly event report\\nYear: 2001\\n\\nAbstract: The workshop took place on Alcácer do Sal, Portugal from May 22nd to May 25th, 2001 with the purpose to discuss approaches to universal usability for the elderly constituency. Elderly citizens are a growing age group within developed countries and their needs have been mostly ignored by Information Technology and Computing as a whole. The surge of mobile communications and universal access materialized in the push for UMTS in Europe provided a strong leitmotif for this meeting. For the better part of a week, a group joining twenty-six people from several different communities gathered to discuss strategic issues arising from the new context. The aim is to provide strategic inputs for major research programs in EU, USA and Japan. The present document contains a summary account of the proceedings.\",\n \"Title: Refereed digital publication of computer graphics educational materials\\nYear: 2004\\n\\nAbstract: Computer Graphics (CG) as a discipline has undergone drastic modifications over the past decades. Indeed the phenomenal progress in both the technical and digital art domains requires educators to master new content and achieve deeper understandings of computers and imagery if they are to keep up with the pace of change. Moreover, as the core field matures, educators in all areas experience a greater need for high-quality curricular resources. Thus, offering excellent educational materials online is an important service to the community. Such support will empower both young and seasoned educators alike to benefit from and contribute to the work of others.\",\n \"Title: Experimental Evaluation of a Trainable Scribble Recognizer for Calligraphic Interfaces\\nYear: 2001\\n\\nAbstract: This paper describes a trainable recognizer for hand-drawn sketches using geometric features. We compare three different learning algorithms and select the best approach in terms of cost-performance ratio. The algorithms employ classic machine-learning techniques using a clustering approach. Experimental results show competing performance (95.1%) with the non-trainable recognizer (95.8%) previously developed, with obvious gains in flexibility and expandability. In addition, we study both their classification and learning performance with increasing number of examples per class.\",\n \"Title: Identifying Student Types In A Gamified Learning Experience\\nYear: 2014\\n\\nAbstract: Gamification of education is a recent trend, and early experiments showed promising results. Students seem not only to perform better, but also to participate more and to feel more engaged with gamified learning. However, little is known regarding how different students are affected by gamification and how their learning experience may vary. In this paper the authors present a study in which they analyzed student data from a gamified college course and looked for distinct behavioral patterns. The authors clustered students according to their performance throughout the semester, and carried out a thorough analysis of each cluster, regarding many aspects of their learning experience. They clearly found three types of students, each with very distinctive strategies and approaches towards gamified learning: the Achievers, the Disheartened and the Underachievers. A careful analysis allowed them to extensively describe each student type and derive meaningful guidelines, to help carefully tailoring custom gamified experiences for them.\",\n \"Title: Mobile touchscreen user interfaces: bridging the gap between motor-impaired and able-bodied users\\nYear: 2014\\n\\nAbstract: Touchscreen mobile devices are highly customizable, allowing designers to create inclusive user interfaces that are accessible to a broader audience. However, the knowledge to provide this new generation of user interfaces is yet to be uncovered. The goal was to thoroughly study mobile touchscreen interfaces and provide guidelines for informed design. The paper presents an evaluation performed with 15 tetraplegic and 18 able-bodied users that allowed to identify their main similarities and differences within a set of interaction techniques (Tapping, Crossing, and Directional Gesturing) and parameterizations. Results show that Tapping and Crossing are the most similar and easy to use techniques for both motor-impaired and able-bodied users. Regarding Tapping, error rates start to converge at 12 mm, showing to be a good compromise for target size. As for Crossing, it offered a similar level of accuracy; however, larger targets (17 mm) are significantly easier to cross for motor-impaired users. Directional Gesturing was the least inclusive technique. Regarding position, edges showed to be troublesome. For instance, they have shown to increase Tapping precision for disabled users, while decreasing able-bodied users' accuracy when targets are too small (7 mm). It is argued that despite the expected error rate disparity, there are clear resemblances between user groups, thus enabling the development of inclusive touch interfaces. Tapping, a traditional interaction technique, was among the most effective for both target populations, along with Crossing. The main difference concerns Directional Gesturing that in spite of its unconstrained nature shows to be inaccurate for motor-impaired users.\",\n \"Title: Mobile text-entry and visual demands: reusing and optimizing current solutions\\nYear: 2014\\n\\nAbstract: Mobile devices are increasingly used for text-entry in contexts where visual attention is fragmented and graphical information is inadequate, yet the current solutions to typing on virtual keyboards make it a visually demanding task. This work looks at assistive technologies and interface attributes as tools to ease the task. Two within-subject experiments were performed with 23 and 17 participants, respectively. The first experiment aimed to understand how walking affected text-entry performance and additionally to assess how effective assistive technologies can be in mobile contexts. In the second experiment, adaptive keyboards featuring character prediction and pre-attentive attributes to ease visual demands of text-entry interfaces were developed and evaluated. It has been found that both text-input speed and overall quality are affected in mobile situations. Contrary to the expectations, assistive technologies proved ineffective with visual feedback. The second experiment showed that pre-attentive attributes do not affect users' performance in task-entry tasks, even though a 3.3---4.3 % decrease in error rates was measured. It was found that users reduce walking speed to compensate for challenges placed by mobile text-entry. Caution should be exercised when transferring assistive technologies to mobile contexts, since they need adaptations to address mobile users' needs. Also, while pre-attentive attributes seemingly have no effect on experienced QWERTY typists' performance, they showed promise for both novice users and typists in attention-demanding contexts.\",\n \"Title: Physio@Home: Exploring Visual Guidance and Feedback Techniques for Physiotherapy Exercises\\nYear: 2015\\n\\nAbstract: Physiotherapy patients exercising at home alone are at risk of re-injury since they do not have corrective guidance from a therapist. To explore solutions to this problem, we designed Physio@Home, a prototype that guides people through prerecorded physiotherapy exercises using real-time visual guides and multi-camera views. Our design addresses several aspects of corrective guidance, including: plane and range of movement, joint positions and angles, and extent of movement. We evaluated our design, com-paring how closely people could follow exercise movements under various feedback conditions. Participants were most accurate when using our visual guide and multi-views. We provide suggestions for exercise guidance systems drawn from qualitative findings on visual feedback complexity.\",\n \"Title: ThumbCam: Returning to single touch interactions to explore 3D virtual environments\\nYear: 2014\\n\\nAbstract: Three-dimensional virtual environments are present in many different applications, being used even in small handheld devices. To navigate in these environments using such devices, most of current solutions rely on multi-touch interactions. However, previous works have already stated that multi-touch gestures on smartphones are not always feasible. In this work we present ThumbCam, a novel single-touch technique for camera manipulation on 3D virtual environments. With our solution, the user is able to move and look around and circle points of interest, while interacting using only his thumb. We compare ThumbCam with other state-of-the-art techniques, showing that it can offer more operations with a single touch. A qualitative user evaluation revealed that users found our solution appealing.\",\n \"Title: Interactive two-sided transparent displays: designing for collaboration\\nYear: 2014\\n\\nAbstract: Transparent displays can serve as an important collaborative medium supporting face-to-face interactions over a shared visual work surface. Such displays enhance workspace awareness: when a person is working on one side of a transparent display, the person on the other side can see the other's body, hand gestures, gaze and what he or she is actually manipulating on the shared screen. Even so, we argue that designing such transparent displays must go beyond current offerings if it is to support collaboration. First, both sides of the display must accept interactive input, preferably by at least touch and / or pen, as that affords the ability for either person to directly interact with the workspace items. Second, and more controversially, both sides of the display must be able to present different content, albeit selectively. Third (and related to the second point), because screen contents and lighting can partially obscure what can be seen through the surface, the display should visually enhance the actions of the person on the other side to better support workspace awareness. We describe our prototype FACINGBOARD-2 system, where we concentrate on how its design supports these three collaborative requirements.\",\n \"Title: Combining EEG Data with Place and Plausibility Responses as an Approach to Measuring Presence in Outdoor Virtual Environments\\nYear: 2014\\n\\nAbstract: Outdoor virtual environments (OVEs) are becoming increasingly popular, as they allow a sense of presence in places that are inaccessible or protected from human intervention. These virtual environments (VEs) need to address physical modalities other than vision and hearing. We analyze the influence of four different physical modalities (vision, hearing, haptics, and olfaction) on the sense of presence on a virtual journey through the sea and the Laurissilva Forest of Funchal, Portugal. We applied Slater et al.'s (2010) method together with data gathered by the Emotiv EPOC EEG in an OVE setting. In such a setting, the combination of haptics and hearing are more important than the typical virtual environment (vision and hearing) in terms of place and plausibility illusions. Our analysis is particularly important for designers interested in crafting similar VEs because we classify different physical modalities according to their importance in enhancing presence.\",\n \"Title: Using fuzzy logic to recognize geometric shapes interactively\\nYear: 2000\\n\\nAbstract: This paper presents a simple method, based on fuzzy logic, to recognize multi-stroke sketches of geometric shapes and uni-stroke gestural commands. It uses temporal adjacency and global geometric properties of figures to recognize a simple vo- cabulary of geometric shapes drawn in different line styles. The geometric features used (convex hull, largest-area inscribed and smallest-area enclosing polygons, perimeter and area ratios) are invariant with rotation and scale of figures. Through experimen- tal evaluation we have found the method very usable with accept- able recognition rates although the multi-stroke approach poses problems in choosing appropriate values for timeouts. Although we have privileged simplicity over robustness, the method has proved suitable for interactive applications.\",\n \"Title: Visual languages for sketching documents\\nYear: 2000\\n\\nAbstract: We present a visual approach to layout documents as hand-drawn compositions of simple geometric shapes. This approach is based on a grammatical method to support document design through sketch recognition which explicitly addresses visual ambiguity. We use fuzzy relational adjacency grammars to provide a natural handling of fuzzy logic and spatial relation syntax in a single unified formalism. Fuzzy relations enable us to replace spatial constraints such as “a is above b” or “a is parallel to c” by quantities that express a degree of uncertainty. Their use allows us to associate a “measure of goodness” to all data and to intermediate and final results. We developed a prototype application that supports document layout sketching in a simple way\",\n \"Title: A Survey on Implicit Surface Polygonization\\nYear: 2015\\n\\nAbstract: Implicit surfaces (IS) are commonly used in image creation, modeling environments, modeling objects, and scientific data visualization. In this article, we present a survey of different techniques for fast visualization of IS. The main classes of visualization algorithms are identified along with the advantages of each in the context of the different types of IS commonly used in computer graphics. We focus closely on polygonization methods, as they are the most suited to fast visualization. Classification and comparison of existing approaches are presented using criteria extracted from current research. This enables the identification of the best strategies according to the number of specific requirements, such as speed, accuracy, quality, or stylization.\",\n \"Title: Clustering Students Based on Motivation to Learn: A Blended Learning Approach\\nYear: 2015\\n\\nAbstract: Technological advances during the last decade have provided huge possibilities to support e-learning. However, there are still concerns regarding Return-on-Investment ROI of e-learning, its sustainability within organizational bound-aries and effectiveness across potential learner groups. Much previous research has concentrated on learners' motivation, satisfaction, and retention. This leaves room for further research to identify alternative and innovative ways to center design on students' concerns when learning online. The authors' work focuses on designing workable courseware usability evaluation methods to differentiate students to improve learning-support frameworks from both pedagogical and system perspectives. The authors' results suggest that students can be grouped in three clusters based on their motivation to e-Learn. Instructors could predict which cluster a new student belongs to, making it possible to anticipate usability issues that most affect results. This also facilitates pedagogical interventions that could help at-risk learners, contributing to the retention rate.\",\n \"Title: Expeditious illustration of layer-cake models on and above a tactile surface.\\nYear: 2016\\n\\nAbstract: Too often illustrating and visualizing 3D geological concepts are performed by sketching in 2D mediums, which may limit drawing performance of initial concepts. Here, the potential of expeditious geological modeling brought by hand gestures is explored. A spatial interaction system was developed to enable rapid modeling, editing, and exploration of 3D layer-cake objects. User interactions are acquired with motion capture and touch screen technologies. Virtual immersion is guaranteed by using stereoscopic technology. The novelty consists of performing expeditious modeling of coarse geological features with only a limited set of hand gestures. Results from usability-studies show that the proposed system is more efficient when compared to a windows-icon-menu-pointer modeling application. Display Omitted New spatial interaction system to rapidly sketch and explore geological models.Stereoscopic visualization approach to direct manipulation in 3-space.Approach uses the continuous interaction space over a multi-touch surface.Comparative study shows advantage over a mouse+keyboard approach.User study identifies a more efficient solution to model layer-caked models.\",\n \"Title: Building the world-wide community of graphics educators\\nYear: 2004\\n\\nAbstract: The fast pace of change in the computer graphics (CG) field makes it difficult for educators to continually design up to date, meaningful and robust curricula that address the full potential of the technology. We feel that the most valuable resource for CG educators is access to an international community of people who teach digital media in all forms. This forum will be a discussion about how we can build that community and how we can provide a method for the people involved to share information.\",\n \"Title: Computer graphics educational materials source policies and status report\\nYear: 2004\\n\\nAbstract: CGEMS, the Computer Graphics Educational Materials Source, aims at supporting a worldwide community of Computer Graphics educators. Our goal in developing this service is to provide a means for educators' work to be appraised and disseminated to other members of the community through an online server for refereed educational content. Since it was presented last year at SIGGRAPH in San Diego, CGEMS has evolved into a full-fledged peer-reviewed medium. This paper presents the current state of the server, reports on work developed and dissemination activities, but most importantly describes how and why educators should submit content.\",\n \"Title: SleeveAR: Augmented Reality for Rehabilitation using Realtime Feedback.\\nYear: 2016\\n\\nAbstract: We present an intelligent user interface that allows people to perform rehabilitation exercises by themselves under the offline supervision of a therapist. Every year, many people suffer injuries that require rehabilitation. This entails considerable time overheads since it requires people to perform specified exercises under the direct supervision of a therapist. Therefore it is desirable that patients continue performing exercises outside the clinic (for instance at home, thus without direct supervision), to complement in-clinic physical therapy. However, to perform rehabilitation tasks accurately, patients need appropriate feedback, as otherwise provided by a physical therapist, to ensure that these unsupervised exercises are correctly executed. Different approaches address this problem, providing feedback mechanisms to aid rehabilitation. Unfortunately, test subjects frequently report having trouble to completely understand the feedback thus provided, which makes it hard to correctly execute the prescribed movements. Worse, injuries may occur due to incorrect performance of the prescribed exercises, which severely hinders recovery. SleeveAR is a novel approach to provide real-time, active feedback, using multiple projection surfaces to provide effective visualizations. Empirical evaluation shows the effectiveness of our approach as compared to traditional video-based feedback. Our experimental results show that our intelligent UI can successfully guide subjects through an exercise prescribed (and demonstrated) by a physical therapist, with performance improvements between consecutive executions, a desirable goal to successful rehabilitation.\",\n \"Title: Eery Space: Facilitating Virtual Meetings Through Remote Proxemics\\nYear: 2015\\n\\nAbstract: Virtual meetings have become increasingly common with modern video-conference and collaborative software. While they allow obvious savings in time and resources, current technologies add unproductive layers of protocol to the flow of communication between participants, rendering the interactions far from seamless. In this work we introduce Remote Proxemics, an extension of proxemics aimed at bringing the syntax of co-located proximal interactions to virtual meetings. We propose Eery Space, a shared virtual locus that results from merging multiple remote areas, where meeting participants' are located side-by-side as if they shared the same physical location. Eery Space promotes collaborative content creation and seamless mediation of communication channels based on virtual proximity. Results from user evaluation suggest that our approach is sufficient to initiate proximal exchanges regardless of their geolocation, while promoting smooth interactions between local and remote people alike.\",\n \"Title: Mixing images and sketches for retrieving vector drawings\\nYear: 2004\\n\\nAbstract: Current approaches to content-based retrieval of multimedia data usually rely either on query by example or on sketches of the desired image, but not on both. In this paper, we propose a new query specification scheme, where digital images are combined with sketches, after vectorization, taking advantage of both methods. We selected a set of algorithms to perform image vectorization, taking into account the trade-off between vector image quality and processing time. This method of specifying queries is part of a system to retrieve vector drawings, which we briefly describe in this paper.\",\n \"Title: Sketch-Based Mesh Augmentation\\nYear: 2005\\n\\nAbstract: This paper describes a sketch-based method for augmenting geometric meshes with variable-scale sharp features. Such mesh editing operations provide a powerful way to exploit artist's natural sketching abilities for content creation using existing mesh libraries. We use adaptive subdivision to refine the mesh only in the region of the features and embed the augmentations into the input mesh, maintaining a unified representation. Moreover, we present new templates for adaptive subdivision that minimizes the high-valence vertex count while maximizing the number of quadrilaterals in the new mesh, thereby improving its quality.\",\n \"Title: Cascading recognizers for ambiguous calligraphic interaction\\nYear: 2004\\n\\nAbstract: Throughout the last decade many approaches have been made to the problem of developing CAD systems that are usable in the early stages of product ideation. Although most of these approaches rely on some kind of drawing paradigm and on the paper-and-pencil metaphor, only a few of them deal with the ambiguity that is inherent to natural languages in general and to sketching in particular. Also the paper-and-pencil metaphor has not in most cases been fully accomplished, since many gesture-based interfaces resort to secondary buttons and modifier keys in order to make command strokes easier to differentiate from their geometry instantiating counterparts. In this paper we describe the architecture of GIDeS++, a sketch-based 3D modeling system that approaches these problems in three different ways: by dealing with ambiguity and exploring it to the user's benefit; by reducing the command set and thus minimizing the cognitive load on the user; and by cascading different types of gesture recognizers, which allows interaction to resort only to the button located on the tip of an electronic stylus.\",\n \"Title: Relating gaming habits with student performance in a gamified learning experience\\nYear: 2014\\n\\nAbstract: Gamified education is a novel concept, and early trials show its potential to engage students and improve their performance. However, little is known about how different students learn with gamification, and how their gaming habits influence their experience. In this paper we present a study where data regarding student performance and gaming preferences, from a gamified engineering course, was collected and analyzed. We performed cluster analysis to understand what different kinds of students could be observed in our gamified experience, and how their behavior could be correlated to their gaming characteristics. We identified four main student types: the Achievers, the Regular students, the Halfhearted students, and the Underachievers, all representing different strategies towards the course and with different gaming preferences. Here we will thoroughly describe each student type and address how different gaming preferences might have impacted the students' learning experience.\",\n \"Title: Accelerating Occlusion Rendering on a GPU via Ray Classification.\\nYear: 2015\\n\\nAbstract: Accurately rendering occlusions is required when ray-tracing objects to achieve more realistic rendering of scenes. Indeed, soft phenomena such as shadows and ambient occlusion can be achieved with stochastic ray tracing techniques. However, computing randomized incoherent ray-object intersections can be inefficient. This is problematic in Graphics Processing Unit GPU applications, where thread divergence can significantly lower throughput. The authors show how this issue can be mitigated using classification techniques that sort rays according to their spatial characteristics. Still, classifying occlusion terms requires sorting millions of rays. This is offset by savings in rendering time, which result from a more coherent ray distribution. The authors survey and test different ray classification techniques to identify the most effective. The best results were achieved when sorting rays using a compress-sort-decompress approach using 32-bit hash keys.\",\n \"Title: Early Prediction of Student Profiles Based on Performance and Gaming Preferences.\\nYear: 2016\\n\\nAbstract: State of the art research shows that gamified learning can be used to engage students and help them perform better. However, most studies use a one-size-fits-all approach to gamification, where individual differences and needs are ignored. In a previous study, we identified four types of students attending a gamified college course, characterized by different levels of performance, engagement and ...\",\n \"Title: Talaria: Continuous Drag & Drop on a Wall Display.\\nYear: 2016\\n\\nAbstract: We present an interaction technique combining tactile actions and midair pointing to access out-of-reach content on large displays without the need to walk across the display. Users can start through a touch gesture on the display surface and finish midair by pointing to push content away or inversely to retrieve a content. The technique takes advantage of well-known semantics of pointing in human-to-human interaction. These, coupled with the semantics of proximal relations and deictic proxemics make the proposed technique very powerful as it leverages on well-understood human-human interaction modalities. Experimental results show this technique to outperform direct tactile interaction on dragging tasks. From our experience we derive four guidelines for interaction with large-scale displays.\",\n \"Title: Effects of speed and transitions on target-based travel techniques.\\nYear: 2016\\n\\nAbstract: Travel on Virtual Environments is the simple action where a user moves from a starting point A to a target point B. Choosing an incorrect type of technique could compromise the Virtual Reality experience and cause side effects such as spatial disorientation, fatigue and cybersickness. The design of effective travelling techniques demands to be as natural as possible, thus real walking techniques presents better results, despite their physical limitations. Approaches to surpass these limitations employ techniques that provide an indirect travel metaphor such as point-steering and target-based. In fact, target-based techniques evince a reduction in fatigue and cybersickness against the point-steering techniques, even though providing less control. In this paper we investigate further effects of speed and transition on target-based techniques on factors such as comfort and cybersickness using a Head-Mounted Display setup.\",\n \"Title: The benefits of DOF separation in mid-air 3D object manipulation.\\nYear: 2016\\n\\nAbstract: Object manipulation is a key feature in almost every virtual environment. However, it is difficult to accurately place an object in immersive virtual environments using mid-air gestures that mimic interactions in the physical world, although being a direct and natural approach. Previous research studied mouse and touch based interfaces concluding that separation of degrees-of-freedom (DOF) led to improved results. In this paper, we present the first user evaluation to assess the impact of explicit 6 DOF separation in mid-air manipulation tasks. We implemented a technique based on familiar virtual widgets that allow single DOF control, and compared it against a direct approach and PRISM, which dynamically adjusts the ratio between hand and object motions. Our results suggest that full DOF separation benefits precision in spatial manipulations, at the cost of additional time for complex tasks. From our results we draw guidelines for 3D object manipulation in mid-air.\",\n \"Title: Perceiving depth: optical versus video see-through.\\nYear: 2016\\n\\nAbstract: Head-Mounted Displays (HMDs) and similar 3D visualization devices are becoming ubiquitous. Going a step forward, HMD see-through systems bring virtual objects to real world settings, allowing augmented reality to be used in complex engineering scenarios. Of these, optical and video see-through systems differ on how the real world is captured by the device. To provide a seamless integration of real and virtual imagery, the absolute depth and size of both virtual and real objects should match appropriately. However, these technologies are still in their early stages, each featuring different strengths and weaknesses which affect the user experience. In this work we compare optical to video see-through systems, focusing on depth perception via exocentric and egocentric methods. Our study pairs Meta Glasses, an off-the-shelf optical see-through, to a modified Oculus Rift setup with attached video-cameras, for video see-through. Results show that, with the current hardware available, the video see-through configuration provides better overall results. These experiments and our results can help interaction designers for both virtual and augmented reality conditions.\",\n \"Title: Multi-GPU-based detection of protein cavities using critical points.\\nYear: 2017\\n\\nAbstract: Protein cavities are specific regions on the protein surface where ligands (small molecules) may bind. Such cavities are putative binding sites of proteins for ligands. Usually, cavities correspond to voids, pockets, and depressions of molecular surfaces. The location of such cavities is important to better understand protein functions, as needed in, for example, structure-based drug design. This article introduces a geometric method to detecting cavities on the molecular surface based on the theory of critical points. The method, called CriticalFinder, differs from other surface-based methods found in the literature because it directly uses the curvature of the scalar field (or function) that represents the molecular surface, instead of evaluating the curvature of the Connolly function over the molecular surface. To evaluate the accuracy of CriticalFinder, we compare it to other seven geometric methods (i.e., LIGSITECS, GHECOM, ConCavity, POCASA, SURFNET, PASS, and Fpocket). The benchmark results show that CriticalFinder outperforms those methods in terms of accuracy. In addition, the performance analysis of the GPU implementation of CriticalFinder in terms of time consumption and memory space occupancy was carried out.\",\n \"Title: Studying student differentiation in gamified education: A long-term study.\\nYear: 2017\\n\\nAbstract: Gamified learning is a novel concept that according to recent studies, can increase student activity and improve learning outcomes. However, little is known about how different students experience and are engaged by it. We present a long-term study which identified distinct behavioral and performance patterns in participants taking a gamified college course. Our study lasted for three years, during which we deployed three consecutive instances of the course, each featuring improvements based on student feedback from the previous instances. To understand how different students behaved in our gamified experience, according to their daily performance, we performed cluster analysis and assessed student engagement in the last year using a formal instrument. We then did a cluster-wise analysis using different performance and behavioral measures, to further assess and characterize every cluster. To wit, we identified six different student clusters, each featuring different behaviors and performance levels. However, only four were present in the last year, which differed in terms of engagement with the course. In this paper we carefully describe each student cluster, explain how they evolved, and derive meaningful design lessons.\",\n \"Title: Hip-directed walking-in-place using a single depth camera.\\nYear: 2017\\n\\nAbstract: Walking-in-place (WIP) is a locomotion technique that allows users to travel in virtual environments (VEs) without significantly changing their physical position on the floor. Hip-directed steering(HDS) is a novel physical technique for controlling direction changes in virtual travel using hip movements. We present an WIP-based navigation approach for controlling locomotion in VEs that combines the speed and direction in a scenario similar to a domestic setup in which people interact with a flat screen. Their physical motion data are captured by one depth camera properly aligned with the screen and oriented toward the user.\",\n \"Title: Using custom transformation axes for mid-air manipulation of 3D virtual objects\\nYear: 2017\\n\\nAbstract: Virtual Reality environments are able to offer natural interaction metaphors. However, it is difficult to accurately place virtual objects in the desired position and orientation using gestures in mid-air. Previous research concluded that the separation of degrees-of-freedom (DOF) can lead to better results, but these benefits come with an increase in time when performing complex tasks, due to the additional number of transformations required. In this work, we assess whether custom transformation axes can be used to achieve the accuracy of DOF separation without sacrificing completion time. For this, we developed a new manipulation technique, MAiOR, which offers translation and rotation separation, supporting both 3-DOF and 1-DOF manipulations, using personalized axes for the latter. Additionally, it also has direct 6-DOF manipulation for coarse transformations, and scaled object translation for increased placement. We compared MAiOR against an exclusively 6-DOF approach and a widget-based approach with explicit DOF separation. Results show that, contrary to previous research suggestions, single DOF manipulations are not appealing to users. Instead, users favored 3-DOF manipulations above all, while keeping translation and rotation independent.\",\n \"Title: Design and evaluation of a novel out-of-reach selection technique for VR using iterative refinement.\\nYear: 2017\\n\\nAbstract: •A taxonomy to classify reach, cardinality and refinement on out-of-reach selections.•We propose PRECIOUS, a novel out-of-reach selection technique.•PRECIOUS employs an iterative progressive refinement strategy in Virtual Reality.•User evaluation comparing PRECIOUS against state-of-the-art out-of-reach approaches.•PRECIOUS is a versatile approach, combining accuracy with consistent selection times.\",\n \"Title: Geometric Detection Algorithms for Cavities on Protein Surfaces in Molecular Graphics: A Survey.\\nYear: 2017\\n\\nAbstract: Detecting and analysing protein cavities provides significant information about active sites for biological processes (e.g. protein-protein or protein-ligand binding) in molecular graphics and modelling. Using the three-dimensional (3D) structure of a given protein (i.e. atom types and their locations in 3D) as retrieved from a PDB (Protein Data Bank) file, it is now computationally viable to determine a description of these cavities. Such cavities correspond to pockets, clefts, invaginations, voids, tunnels, channels and grooves on the surface of a given protein. In this work, we survey the literature on protein cavity computation and classify algorithmic approaches into three categories: evolution-based, energy-based and geometry-based. Our survey focuses on geometric algorithms, whose taxonomy is extended to include not only sphere-, grid- and tessellation-based methods, but also surface-based, hybrid geometric, consensus and time-varying methods. Finally, we detail those techniques that have been customized for GPU (graphics processing unit) computing.\",\n \"Title: Using iterative refinement for out-of-reach selection in VR.\\nYear: 2017\\n\\nAbstract: In Virtual Reality (VR), the action of selecting virtual objects outside arms-reach still poses significant challenges. In this work, after classifying, with a new taxonomy, and analyzing existing solutions, we propose a novel technique to perform out-of-reach selections in VR. It uses natural pointing gestures, a modifiable cone as selection volume, and an iterative progressive refinement strategy. This can be considered a VR implementation of a discrete zoom approach, although we modify usersu0027 position instead of the field-of-view. When the cone intersects several objects, users can either activate the refinement process, or trigger a multiple object selection. We compared our technique against two techniques from literature. Our results show that, although not being the fastest, it is a versatile approach due to the lack of errors and uniform completion times.\",\n \"Title: Assessing the usability of tile-based interfaces to visually navigate 3-D parameter domains.\\nYear: 2018\\n\\nAbstract: •A generic tile-based interface is proposed to navigate 3D parameter spaces.•Users easily navigate along tiles arranged in a rhombille pattern.•Usability study reveals similar performance results between tile-based, 1-D sliders and specialized widgets.•Tile-based interfaces are suitable to navigate color and super-shape spaces.•Rotation space navigation is more challenging via tile-based interface.\",\n \"Title: Explicit design of transfer functions for volume-rendered images by combining histograms, thumbnails, and sketch-based interaction.\\nYear: 2018\\n\\nAbstract: Visual quality of volume rendering for medical imagery strongly depends on the underlying transfer function. Conventional Windows–Icons–Menus–Pointer interfaces typically refer the user to browse a lengthy catalog of predefined transfer functions or to pain-staking refine the transfer function by clicking and dragging several independent handles. To turn the standard design process less difficult and tedious, this paper proposes novel interactions on a sketch-based interface that supports the design of 1D transfer functions via touch gestures to directly control voxel opacity and easily assign colors. User can select different types of transfer function shapes including ramp function, free hand curve drawing, and slider bars similar to those of a mixing table. An assorted array of thumbnails provides an overview of the data when editing the transfer function. User performance is evaluated by comparing the time and effort necessary to complete a number of tests with sketch-based and conventional interfaces. Users were able to more rapidly explore and understand volume data using the sketch-based interface, as the number of design iterations necessary to obtain a desirable transfer function was reduced. In addition, informal evaluation sessions carried out with professionals (two senior radiologists, a general surgeon and two scientific illustrators) provided valuable feedback on how suitable the sketch-based interface is for illustration, patient communication and medical education.\",\n \"Title: Keep my head on my shoulders!: why third-person is bad for navigation in VR\\nYear: 2018\\n\\nAbstract: Head-Mounted Displays are useful to place users in virtual reality (VR). They do this by totally occluding the physical world, including users' bodies. This can make self-awareness problematic. Indeed, researchers have shown that users' feeling of presence and spatial awareness are highly influenced by their virtual representations, and that self-embodied representations (avatars) of their anatomy can make the experience more engaging. On the other hand, recent user studies show a penchant towards a third-person view of one's own body to seemingly improve spatial awareness. However, due to its unnaturality, we argue that a third-person perspective is not as effective or convenient as a first-person view for task execution in VR. In this paper, we investigate, through a user evaluation, how these perspectives affect task performance and embodiment, focusing on navigation tasks, namely walking while avoiding obstacles. For each perspective, we also compare three different levels of realism for users' representation, specifically a stylized abstract avatar, a mesh-based generic human, and a real-time point-cloud rendering of the users' own body. Our results show that only when a third-person perspective is coupled with a realistic representation, a similar sense of embodiment and spatial awareness is felt. In all other cases, a first-person perspective is still better suited for navigation tasks, regardless of representation.\",\n \"Title: A New Approach To Walking In Place\\nYear: 2013\\n\\nAbstract: Walking in Place (WIP) is an important locomotion technique used in virtual environments. This paper proposes a new approach to WIP, called Speed-Amplitude-Supported Walking-in-Place (SAS-WIP), which allows people, when walking along linear paths, to control their virtual speed based on footstep amplitude and speed metrics. We argue that our approach allows users to better control the virtual distance covered by the footsteps, achieve higher average speeds and experience less fatigue than when using state-of-the-art methods based on footstep frequency, called GUD-WIP.An in-depth user evaluation with twenty participants compared our approach to GUD-WIP on common travel tasks over a range of short, medium and long distances. We measured task performance using four distinct criteria: effectiveness, precision, efficiency and speed. The results show that SAS-WIP is both more efficient and faster than GUD-WIP when walking long distances while being more effective and precise over short distances. When asked their opinion via a post-test questionnaire, participants preferred SAS-WIP to GUD-WIP and reported experiencing less fatigue, having more fun and having a greater level of control when using our approach.\",\n \"Title: VRRRRoom: Virtual Reality for Radiologists in the Reading Room.\\nYear: 2017\\n\\nAbstract: Reading room conditions such as illumination, ambient light, human factors and display luminance, play an important role on how radiologists analyze and interpret images. Indeed, serious diagnostic errors can appear when observing images through everyday monitors. Typically, these occur whenever professionals are ill-positioned with respect to the display or visualize images under improper light and luminance conditions. In this work, we show that virtual reality can assist radiodiagnostics by considerably diminishing or cancel out the effects of unsuitable ambient conditions. Our approach combines immersive head-mounted displays with interactive surfaces to support professional radiologists in analyzing medical images and formulating diagnostics. We evaluated our prototype with two senior medical doctors and four seasoned radiology fellows. Results indicate that our approach constitutes a viable, flexible, portable and cost-efficient option to traditional radiology reading rooms.\",\n \"Title: Warping Deixis - Distorting Gestures to Enhance Collaboration.\\nYear: 2019\\n\\nAbstract: When engaged in communication, people often rely on pointing gestures to refer to out-of-reach content. However, observers frequently misinterpret the target of a pointing gesture. Previous research suggests that to perform a pointing gesture, people place the index finger on or close to a line connecting the eye to the referent, while observers interpret pointing gestures by extrapolating the referent using a vector defined by the arm and index finger. In this paper we present Warping Deixis, a novel approach to improving the perception of pointing gestures and facilitate communication in collaborative Extended Reality environments. By warping the virtual representation of the pointing individual, we are able to match the pointing expression to the observer's perception. We evaluated our approach in a co-located side by side virtual reality scenario. Results suggest that our approach is effective in improving the interpretation of pointing gestures in shared virtual environments.\",\n \"Title: A Survey on 3D Virtual Object Manipulation: From the Desktop to Immersive Virtual Environments.\\nYear: 2019\\n\\nAbstract: Interactions within virtual environments often require manipulating 3D virtual objects. To this end, researchers have endeavoured to find efficient solutions using either traditional input devices or focusing on different input modalities, such as touch and mid-air gestures. Different virtual environments and diverse input modalities present specific issues to control object position, orientation and scaling: traditional mouse input, for example, presents non-trivial challenges because of the need to map between 2D input and 3D actions. While interactive surfaces enable more natural approaches, they still require smart mappings. Mid-air gestures can be exploited to offer natural manipulations mimicking interactions with physical objects. However, these approaches often lack precision and control. All these issues and many others have been addressed in a large body of work. In this article, we survey the state-of-the-art in 3D object manipulation, ranging from traditional desktop approaches to touch and mid-air interfaces, to interact in diverse virtual environments. We propose a new taxonomy to better classify manipulation properties. Using our taxonomy, we discuss the techniques presented in the surveyed literature, highlighting trends, guidelines and open challenges, that can be useful both to future research and to developers of 3D user interfaces.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":102,"string":"102"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":70,"string":"70"}}},{"rowIdx":71,"cells":{"question_id":{"kind":"string","value":"Ivan Damg rd"},"question":{"kind":"string","value":"Generate an abstract for the title \"Non-Interactive Verifiable Secret Sharing For Monotone Circuits.\" using the following items: 1. Secret sharing\n2. Verifiable scheme\n3. Monotone Boolean circuit\n4. Non-interactive \n5. Efficient construction"},"answer":{"kind":"string","value":"We propose a computationally secure and non-interactive verifiable secret sharing scheme that can be efficiently constructed from any monotone Boolean circuit. By non-interactive we mean that the dealer needs to be active only once, where he posts a public message as well as a private message to each shareholder. In the random oracle model, we can even avoid interaction between shareholders. By efficient, we mean that we avoid generic zero-knowledge techniques. Such efficient constructions were previously only known from linear secret sharing schemes LSSS. It is believed that the class of access structures that can be handled with polynomial size LSSS is incomparable to the class that can be recognized by polynomial size monotone circuits, so in this sense we extend the class of access structures with efficient and non-interactive VSS."},"correct_answer":{"kind":"string","value":"We propose a computationally secure and non-interactive verifiable secret sharing scheme that can be efficiently constructed from any monotone Boolean circuit. By non-interactive we mean that the dealer needs to be active only once, where he posts a public message as well as a private message to each shareholder. In the random oracle model, we can even avoid interaction between shareholders. By efficient, we mean that we avoid generic zero-knowledge techniques. Such efficient constructions were previously only known from linear secret sharing schemes LSSS. It is believed that the class of access structures that can be handled with polynomial size LSSS is incomparable to the class that can be recognized by polynomial size monotone circuits, so in this sense we extend the class of access structures with efficient and non-interactive VSS."},"documents":{"kind":"list like","value":["Title: Convertible Undeniable Signatures\nYear: 1990\n\nAbstract: We introduce a new concept called convertible undeniable signature schemes. In these schemes, release of a single bit string by the signer turns all of his signatures, which were originally undeniable\n signatures, into ordinary digital signatures. We prove that the existence of such schemes is implied by the existence of digital\n signature schemes. Then, looking at the problem more practically, we present a very efficient convertible undeniable signature\n scheme. This scheme has the added benefit that signatures can also be selectively converted.","Title: Entangled Cloud Storage.\nYear: 2016\n\nAbstract: Entangled cloud storage (Aspnes et¿al., ESORICS 2004) enables a set of clients to \\\"entangle\\\" their files into a single clew to be stored by a (potentially malicious) cloud provider. The entanglement makes it impossible to modify or delete significant part of the clew without affecting all files encoded in the clew. A clew keeps the files in it private but still lets each client recover his own data by interacting with the cloud provider; no cooperation from other clients is needed. At the same time, the cloud provider is discouraged from altering or overwriting any significant part of the clew as this will imply that none of the clients can recover their files.We put forward the first simulation-based security definition for entangled cloud storage, in the framework of universal composability (Canetti, 2001). We then construct a protocol satisfying our security definition, relying on an entangled encoding scheme based on privacy-preserving polynomial interpolation; entangled encodings were originally proposed by Aspnes et¿al. as useful tools for the purpose of data entanglement. As a contribution of independent interest we revisit the security notions for entangled encodings, putting forward stronger definitions than previous work (that for instance did not consider collusion between clients and the cloud provider).Protocols for entangled cloud storage find application in the cloud setting, where clients store their files on a remote server and need to be ensured that the cloud provider will not modify or delete their data illegitimately. Current solutions, e.g.,¿based on Provable Data Possession and Proof of Retrievability, require the server to be challenged regularly to provide evidence that the clients' files are stored at a given time. Entangled cloud storage provides an alternative approach where any single client operates implicitly on behalf of all others, i.e.,¿as long as one client's files are intact, the entire remote database continues to be safe and unblemished. We model simulation-based security for data entanglement in the cloud.We introduce stronger security notions for entangled encoding schemes.We give a protocol for entangled storage satisfying our simulation-based definition.","Title: Unclonable Group Identification\nYear: 2005\n\nAbstract: We introduce and motivate the concept of unclonable group identification, that provides maximal protection against sharing of iden- tities while still protecting the anonymity of users. We prove that the notion can be realized from any one-way function and suggest a more ecient implementation based on specific assumptions.","Title: On the (im)possibility of basing oblivious transfer and bit commitment on weakened security assumptions\nYear: 1999\n\nAbstract: We consider the problem of basing Oblivious Transfer (OT) and Bit Commitment (BC), with information theoretic security, on seemingly weaker primitives.We introduce a general model for describing such primitives, called Weak Generic Transfer (WGT). This model includes as important special cases Weak Oblivious Transfer (WOT), where both the sender and receiver may learn too much about the other party's input, and a new, more realistic model of noisy channels, called unfair noisy channels. An unfair noisy channel has a known range of possible noise levels; protocols must work for any level within this range against adversaries who know the actual noise level. We give a precise characterization for when one can base OT on WOT. When the deviation of the WOT from the ideal is above a certain threshold, we show that no information-theoretic reductions from OT (even against passive adversaries) and BC exist; when the deviation is below this threshold, we give a reduction from OT (and hence BC) that is information-theoretically secure against active adversaries. For unfair noisy channels we show a similar threshold phenomenon for bit commitment. If the upper bound on the noise is above a threshold (given as a function of the lower bound) then no information-theoretic reduction from OT (even against passive adversaries) or BC exist; when it is below this threshold we give a reduction from BC. As a partial result, we give a reduction from OT to UNC for smaller noise intervals.","Title: Honest Verifier vs Dishonest Verifier in Public Cain Zero-Knowledge Proofs\nYear: 1995\n\nAbstract: This paper presents two transformations of public-coin/Arthur-Merlin proof systems which are zero-knowledge with respect to the honest verifier into (public-coin/Arthur-Merlin) proof systems which are zero-knowledge with respect to any verifier.The first transformation applies only to constant-round proof systems. It builds on Damg氓rd's transformation (see Crypto93), using ordinary hashing functions instead of the interactive hashing protocol (of Naor, Ostrovsky, Venkatesan and Yung - see Crypto92) which was used by Damg氓rd. Consequently, the protocols resulting from our transformation have much lower round-complexity than those derived by Damg氓rd's transformation. As in Damg氓rd's transformation, our transformation preserves statistical/perfect zero-knowledge and does not rely on any computational assumptions. However, unlike Damg氓rd's transformation, the new transformation is not applicable to argument systems or to proofs of knowledge.The second transformation can be applied to proof systems of arbitrary number of rounds, but it only preserves statistical zero-knowledge. It assumes the existence of secure commitment schemes and transforms any public-coin proof which is statistical zero-knowledge with respect to the honest into one which is statistical zero-knowledge (in general). It follows, by a result of Ostrovsky and Wigderson (1993), that any language which is \"hard on the average\" and has a public-coin proof system which is statistical zero-knowledge with respect to the honest verifier, has a proof system which is statistical zero-knowledge (with respect to any verifier).","Title: Zero-Knowledge proofs with low amortized communication from lattice assumptions\nYear: 2012\n\nAbstract: We construct zero-knowledge proofs of plaintext knowledge (PoPK) and correct multiplication (PoPC) for the Regev encryption scheme with low amortized communication complexity. Previous constructions of both PoPK and PoPC had communication cost linear in the size of the public key (roughly quadratic in the lattice dimension, ignoring logarithmic factors). Furthermore, previous constructions of PoPK suffered from one of the following weaknesses: either the message and randomness space were restricted, or there was a super-polynomial gap between the size of the message and randomness that an honest prover chose and the size of which an accepting verifier would be convinced. The latter weakness was also present in the existent PoPC protocols. In contrast, O(n) proofs (for lattice dimension n) in our PoPK and PoPC protocols have communication cost linear in the public key. Thus, we improve the amortized communication cost of each proof by a factor linear in the lattice dimension. Furthermore, we allow the message space to be ℤp and the randomness distribution to be the discrete Gaussian, both of which are natural choices for the Regev encryption scheme. Finally, in our schemes there is no gap between the size of the message and randomness that an honest prover chooses and the size of which an accepting verifier is convinced. Our constructions use the \"MPC-in-the-head\" technique of Ishai et al. (STOC 2007). At the heart of our constructions is a protocol for proving that a value is bounded by some publicly known bound. This uses Lagrange's Theorem that states that any positive integer can be expressed as the sum of four squares (an idea previously used by Boudot (EUROCRYPT 2000)), as well as techniques from Cramer and Damgård (CRYPTO 2009).","Title: Universally Composable Efficient Multiparty Computation from Threshold Homomorphic Encryption\nYear: 2003\n\nAbstract: We present a new general multiparty computation protocol for the cryptographic scenario which is universally composable - in particular, it is secure against an active and adaptive adversary, corrupting any minority of the parties. The protocol is as efficient as the best known statically secure solutions, in particular the number of bits broadcast (which dominates the complexity) is Omega(nk\\C\\), where n is the number of parties, k is a security parameter, and \\C\\ is the size of a circuit doing the desired computation. Unlike previous adaptively secure protocols for the cryptographic model, our protocol does not use non-committing encryption, instead it is based on homomorphic threshold encryption, in particular the Paillier cryptosystem.","Title: Non-interactive Proofs for Integer Multiplication\nYear: 2007\n\nAbstract: We present two universally composable and practical protocols by which a dealer can, verifiably and non-interactively, secret-share an integer among a set of players. Moreover, at small extra cost and using a distributed verifier proof, it can be shown in zero-knowledge that three shared integers a,b,csatisfy ab= c. This implies by known reductions non-interactive zero-knowledge proofs that a shared integer is in a given interval, or that one secret integer is larger than another. Such primitives are useful, e.g., for supplying inputs to a multiparty computation protocol, such as an auction or an election. The protocols use various set-up assumptions, but do not require the random oracle model.","Title: Scalable Secure Multiparty Computation\nYear: 2006\n\nAbstract: We present the first general protocol for secure multiparty computation which is scalable, in the sense that the amortized work per player does not grow, and in some natural settings even vanishes, with the number of players. Our protocol is secure against an active adversary which may adaptively corrupt up to some constant fraction of the players. The protocol can be implemented in a constant number rounds assuming the existence of a \"computationally simple\" pseudorandom generator, or in a small non-constant number of rounds assuming an arbitrary pseu- dorandom generator.","Title: On the Cost of Reconstructing a Secret, or VSS with Optimal Reconstruction Phase\nYear: 2001\n\nAbstract: Consider a scenario where an l-bit secret has been distributed among n players by an honest dealer using some secret sharing scheme. Then, if all players behave honestly, the secret can be reconstructed in one round with zero error probability, and by broadcasting nl bits. We ask the following question: how close to this ideal can we get if up to t players (but not the dealer) are corrupted by an adaptive, active adversary with unbounded computing power? - and where in addition we of course require that the adversary does not learn the secret ahead of reconstruction time. It is easy to see that t = ⌊(n - 1/2⌋ is the maximal value of t that can be tolerated, and furthermore, we show that the best we can hope for is a one-round reconstruction protocol where every honest player outputs the correct secret or \"failure\". For any such protocol with failure probability at most 2-Ω(k), we show a lower bound of Ω(nl + kn2) bits on the information communicated. We further show that this is tight up to a constant factor. The lower bound trivially applies as well to VSS schemes, where also the dealer may be corrupt. Using generic methods, the scheme establishing the upper bound can be turned into a VSS with efficient reconstruction. However, the distribution phase becomes very inefficient. Closing this gap, we present a new VSS protocol where the distribution complexity matches that of the previously best known VSS, but where the reconstruction phase meets our lower bound up to a constant factor. The reconstruction is a factor of n better than previous VSS protocols.We show an application of this to multi-party computation with pre-processing, improving the complexity of earlier similar protocols by a factor of n.","Title: A length-flexible threshold cryptosystem with applications\nYear: 2003\n\nAbstract: We propose a public-key cryptosystem which is derived from the Paillier cryptosystem. The scheme inherits the attractive homomorphic properties of Paillier encryption. In addition, we achieve two new properties: First, all users can use the same modulus when generating key pairs, this allows more efficient proofs of relations between different encryptions. Second, we can construct a threshold decryption protocol for our scheme that is length-flexible, i.e., it can handle efficiently messages of arbitrary length, even though the public key and the secret key shares held by decryption servers are of fixed size. We show how to apply this cryptosystem to build a self-tallying election scheme with perfect ballot secrecy, and to build a length-flexible mix-net which is universally verifiable, where the size of keys and ciphertexts do not depend on the number of mix servers, and is robust against a corrupt minority.","Title: Efficient and secure comparison for on-line auctions\nYear: 2007\n\nAbstract: We propose a protocol for secure comparison of integers based on homomorphic encryption. We also propose a homomorphic encryption scheme that can be used in our protocol and makes it more efficient than previous solutions. Our protocol is well-suited for application in on-line auctions, both with respect to functionality and performance. It minimizes the amount of information bidders need to send, and for comparison of 16 bit numbers with security based on 1024 bit RSA (executed by two parties), our implementation takes 0.28 seconds including all computation and communication. Using precomputation, one can save a factor of roughly 10.","Title: Asynchronous Multiparty Computation: Theory and Implementation\nYear: 2009\n\nAbstract: We propose an asynchronous protocol for general multiparty computation. The protocol has perfect security and communication complexity $\\mathcal{O}(n^2|C|k)$, where n is the number of parties, |C | is the size of the arithmetic circuit being computed, and k is the size of elements in the underlying field. The protocol guarantees termination if the adversary allows a preprocessing phase to terminate, in which no information is released. The communication complexity of this protocol is the same as that of a passively secure solution up to a constant factor. It is secure against an adaptive and active adversary corrupting less than n /3 players. We also present a software framework for implementation of asynchronous protocols called VIFF (Virtual Ideal Functionality Framework), which allows automatic parallelization of primitive operations such as secure multiplications, without having to resort to complicated multithreading. Benchmarking of a VIFF implementation of our protocol confirms that it is applicable to practical non-trivial secure computations.","Title: Verifiable Encryption, Group Encryption, and Their Applications to Separable Group Signatures and Signature Sharing Schemes\nYear: 2000\n\nAbstract: We generalize and improve the security and efficiency of the verifiable encryption scheme of Asokan et al., such that it can rely on more general assumptions, and can be proven secure without assuming random oracles. We extend our basic protocol to a new primitive called verifiable group encryption. We show how our protocols can be applied to construct group signatures, identity escrow, and signature sharing schemes from a wide range of signature, identification, and encryption schemes already in use. In particular, we achieve perfect separability for all these applications, i.e., all participants can choose their signature and encryption schemes and the keys there of independent of each other, even without having these applications in mind.","Title: A practical implementation of secure auctions based on multiparty integer computation\nYear: 2006\n\nAbstract: In this paper we consider the problem of constructing secure auctions based on techniques from modern cryptography. We combine knowledge from economics, threshold cryptography and security engineering to implement secure auctions for practical real-world problems.","Title: A Statistically-Hiding Integer Commitment Scheme Based on Groups with Hidden Order\nYear: 2002\n\nAbstract: We present a statistically-hiding commitment scheme allowing commitment to arbitrary size integers, based on any (Abelian) group with certain properties, most importantly, that it is hard for the committer to compute its order. We also give efficient zero-knowledge protocols for proving knowledge of the contents of commitments and for verifying multiplicative relations over the integers on committed values. The scheme can be seen as a generalization, with a slight modification, of the earlier scheme of Fujisaki and Okamoto [14]. The reasons we revisit the earlier scheme and give some modification to it are as follows: - The earlier scheme [14] has some gaps in the proof of soundness of the associated protocols, one of which presents a non-trivial problem which, to the best of our knowledge, has remained open until now. We fill all the gaps here using additional ideas including minor modification of the form of a commitment. - Although related works such as [8, 3, 10, 4] do not suffer from the main problem we solve here, the reason for this is that they use \"commitments\" with a single base (i.e., of form c = gs mod n). Such commitments, however, cannot satisfy the standard hiding property for commitments, and hence protocols using them cannot in general be (honest-verifier) zero-knowledge nor witness indistinguishable. - In a computationally convincing proof of knowledge where the prover produces the common input (which is the type of protocol we look at here), one cannot completely exclude the possibility that a prover manages to produce a common input on which he can cheat easily. This means that the standard definition of proofs of knowledge cannot be satisfied. Therefore we introduce a new definition for computationally convincing proofs of knowledge, designed to handle the case where the common input is chosen by the (possibly cheating) prover. - Our results apply to any group with suitable properties. In particular, they apply to a much larger class of RSA moduli than the safe prime products proposed in [14] - Potential examples include RSA moduli, class groups and, with a slight modification, even non-Abelian groups.Our scheme can replace the earlier one in various other constructions, such as the efficient interval proofs of Boudot [4] and the efficient proofs for the product of two safe primes proposed by Camenisch and Michels [9].","Title: Cryptography In the Bounded Quantum-Storage Model\nYear: 2005\n\nAbstract: We initiate the study of two-party cryptographic primitives with unconditional security, assuming that the adversary's quantum memory is of bounded size. We show that oblivious transfer and bit commitment can be implemented in this model using protocols where honest parties need no quantum memory, whereas an adversarial player needs quantum memory of size at least n/2 in order to break the protocol, where n is the number of qubits transmitted. This is in sharp contrast to the classical bounded-memory model, where we can only tolerate adversaries with memory of size quadratic in honest players' memory size. Our protocols are efficient, non-interactive and can be implemented using today's technology. On the technical side, a new entropic uncertainty relation involving min-entropy is established.","Title: RFID security: tradeoffs between security and efficiency\nYear: 2006\n\nAbstract: We propose a model and definition for anonymous (group) identification that is well suited for RFID systems. This is based on the definition of Juels and Weis of strong privacy for RFID tags, where we add requirements for completeness and soundness. We also propose a weaker and more realistic definition of privacy. For the case where tags hold independent keys, we prove a conjecture by Juels and Weis, namely in a strongly private and sound RFID system using only symmetric cryptography, a reader must access virtually all keys in the system when reading a tag. It was already known from work by Molnar, Soppera and Wagner that when keys are dependent, the reader only needs to access a logarithmic number of keys, but at a cost in terms of privacy: For that system, privacy is lost if an adversary corrupts just a single tag. We propose protocols offering a new range of tradeoffs between security and efficiency. For instance, the number of keys accessed by a reader to read a tag can be significantly smaller than the number of tags while retaining soundness and privacy, as long as we assume suitable limitations on the adversary.","Title: Unconditionally secure constant-rounds multi-party computation for equality, comparison, bits and exponentiation\nYear: 2006\n\nAbstract: We show that if a set of players hold shares of a value $a \\in \\mathbb{F}_p $ for some prime p (where the set of shares is written [a]p), it is possible to compute, in constant rounds and with unconditional security, sharings of the bits of a, i.e., compute sharings [a0]p, ..., [aℓ−−1]p such that ℓ = ⌈ log2p ⌉, a0,...,al−1∈{0,1} and a = ∑i=0ℓ−−1ai 2i. Our protocol is secure against active adversaries and works for any linear secret sharing scheme with a multiplication protocol. The complexity of our protocol is $\\mathcal{O}(l {\\rm log} l)$ invocations of the multiplication protocol for the underlying secret sharing scheme, carried out in $\\mathcal{O}(1)$ rounds. This result immediately implies solutions to other long-standing open problems such as constant-rounds and unconditionally secure protocols for deciding whether a shared number is zero, comparing shared numbers, raising a shared number to a shared exponent and reducing a shared number modulo a shared modulus.","Title: Expanding Pseudorandom Functions; or: From Known-Plaintext Security to Chosen-Plaintext Security\nYear: 2002\n\nAbstract: Given any weak pseudorandom function, we present a general and efficient technique transforming such a function to a new weak pseudorandom function with an arbitrary length output. This implies, among other things, an encryption mode for block ciphers. The mode is as efficient as known (and widely used) encryption modes as CBC mode and counter (CTR) mode, but is provably secure against chosen-plaintext attack (CPA) already if the underlying symmetric cipher is secure against known-plaintext attack (KPA). We prove that CBC, CTR and Jutla's integrity aware modes do not have this property. In particular, we prove that when using a KPA secure block cipher, then: CBC mode is KPA secure, but need not be CPA secure, Jutla's modes need not be CPA secure, and CTR mode need not be even KPA secure. The analysis is done in a concrete security framework.","Title: Proofs of Partial Knowledge and Simplified Design of Witness Hiding Protocols\nYear: 1994\n\nAbstract: Suppose we are given a proof of knowledge P in which a prover demonstrates that he knows a solution to a given problem instance. Suppose also that we have a secret sharing scheme S on n participants. Then under certain assumptions on P and S, we show how to transform P into a witness indistinguishable protocol, in which the prover demonstrates knowledge of the solution to some subset of n problem instances out of a collection of subsets denned by S. For example, using a threshold scheme, the prover can show that he knows at least d out of n solutions without revealing which d instances are involved. If the instances axe independently generated, we get a witness hiding protocol, even if P did not have this property. Our results can be used to efficiently implement general forms of group oriented identification and signatures. Our transformation produces a protocol with the same number of rounds as P and communication complexity n times that of P. Our results use no unproven complexity assumptions.","Title: Efficient, robust and constant-round distributed RSA key generation\nYear: 2010\n\nAbstract: We present the first protocol for distributed RSA key generation which is constant round, secure against malicious adversaries and has a negligibly small bound on the error probability, even using only one iteration of the underlying primality test on each candidate number.","Title: Unfair Noisy Channels and Oblivious Transfer\nYear: 2004\n\nAbstract: In a paper from EuroCrypt'99, Damgard, Kilian and Salvail show various positive and negative results on constructing Bit Commitment (BC) and Oblivious Transfer (OT) from Unfair Noisy Channels (UNC), i.e., binary symmetric channels where the error rate is only known to be in a certain interval and can be chosen adversarily. They also introduce a related primitive called PassiveUNC. We prove in this paper that any OT protocol that can be constructed based on a PassiveUNC and is secure against a passive adversary can be transformed using a generic \"compiler\" into an OT protocol based on a UNC which is secure against an active adversary. Apart from making positive results easier to prove in general, this also allows correcting a problem in the EuroCrypt'99 paper: There, a positive result was claimed on constructing from UNC an OT that is secure against active cheating. We point out that the proof sketch given for this was incomplete, and we show that a correct proof of a much stronger result follows from our general compilation result and a new technique for transforming between weaker versions of OT with different parameters.","Title: Fast and secure immunization against adaptive man-in-the-middle impersonation\nYear: 1997\n\nAbstract: We present a simple method for constructing identification schemes resilient against impersonation and man-in-the-middle attacks. Though zero-knowledge or witness hiding protocols are known to withstand attacks of the first kind, all such protocols previously proposed suffer from a weakness observed by Bengio et al.: a malicious verifier may simply act as a moderator between the prover and yet another verifier, thus enabling the malicious verifier to pass as the prover. We exhibit a general class of identification schemes that can be efficiently and securely tranformed into identification schemes withstanding an adaptive man-in-the-middle attacker. The complexity of the resulting (witness hiding) schemes is roughly twice that of the originals. Basically, any three-move, public coin identification scheme that is zero knowledge against the honest verifier and that is secure against passive impersonation attacks, is eligible for our transformation. This indicates that we need only seemlingly weak cryptographic intractability assumptions to construct a practical identification scheme resisting adative man-in-the-middle impersonation attacks. Moreover, the required primitive protocols can efficiently be constructed under the factoring or discrete logarithm assumptions.","Title: Scalable and unconditionally secure multiparty computation\nYear: 2007\n\nAbstract: We present a multiparty computation protocol that is unconditionally secure against adaptive and active adversaries, with communication complexity O(Cn)k + O(Dn2)k + poly(nκ), where C is the number of gates in the circuit, n is the number of parties, k is the bit-length of the elements of the field over which the computation is carried out, D is the multiplicative depth of the circuit, and κ is the security parameter. The corruption threshold is t n/3. For passive security the corruption threshold is t n/2 and the communication complexity is O(nC)k. These are the first unconditionally secure protocols where the part of the communication complexity that depends on the circuit size is linear in n. We also present a protocol with threshold t n/2 and complexity O(Cn)k+poly(nκ) based on a complexity assumption which, however, only has to hold during the execution of the protocol - that is, the protocol has so called everlasting security.","Title: Commitment Schemes and Zero-Knowledge Protocols\nYear: 1998\n\nAbstract: Abstract This article is an introduction to two fundamental primitives in cryptographic protocol theory: commitment,schemes and zero-knowledge protocols, and a survey of some new and old results on their existence and the connection between them. 1 What’s in this article?","Title: Client/Server Tradeoffs for Online Elections\nYear: 2002\n\nAbstract: We present various trade offs for voting schemes which, compared to known solutions, allow voters to do less work at the expense of more work done by the tallying servers running the election. One such scheme produces ballots of essentially minimal size while keeping the work load on the tally servers on a practical level. Another type of trade off leads to a voting scheme that remains secure, even if an adversary can monitor all client machines used by voters to participate. This comes at the price of introducing an additional party who is trusted to carry out registration of voters correctly.","Title: Essentially Optimal Universally Composable Oblivious Transfer\nYear: 2008\n\nAbstract: Oblivious transfer is one of the most important cryptographic primitives, both for theoretical and practical reasons and several protocols were proposed during the years. We propose a protocol which is simultaneously optimal on the following list of parameters: Security: it has universal composition. Trust in setup assumptions: only one of the parties needs to trust the setup (and some setup is needed for UC security). Trust in computational assumptions: only one of the parties needs to trust a computational assumption. Round complexity: it uses only two rounds. Communication complexity: it communicates $\\mathcal{O}(1)$ group elements to transfer one out of two group elements. The Big-O notation hides 32, meaning that the communication is probably not optimal, but is essentially optimal in that the overhead is at least constant. Our construction is based on pairings, and we assume the presence of a key registration authority.","Title: DDH-Like assumptions based on extension rings\nYear: 2012\n\nAbstract: We introduce and study a new type of DDH-like assumptions based on groups of prime order q . Whereas standard DDH is based on encoding elements of $\\mathbb{F}_{q}$ \"in the exponent\" of elements in the group, we ask what happens if instead we put in the exponent elements of the extension ring $R_f= \\mathbb{F}_{q}[X]/(f)$ where f is a degree-d polynomial. The decision problem that follows naturally reduces to the case where f is irreducible. This variant is called the d -DDH problem, where 1-DDH is standard DDH. We show in the generic group model that d -DDH is harder than DDH for d 1 and that we obtain, in fact, an infinite hierarchy of progressively weaker assumptions whose complexities lie \"between\" DDH and CDH. This leads to a large number of new schemes because virtually all known DDH-based constructions can very easily be upgraded to be based on d -DDH. We use the same construction and security proof but get better security and moreover, the amortized complexity (e.g, computation per encrypted bit) is the same as when using DDH. We also show that d -DDH, just like DDH, is easy in bilinear groups. We therefore suggest a different type of assumption, the d -vector DDH problems (d -VDDH), which are based on f (X )=X d , but with a twist to avoid problems with reducible polynomials. We show in the generic group model that d -VDDH is hard in bilinear groups and that the problems become harder with increasing d . We show that hardness of d -VDDH implies CCA-secure encryption, efficient Naor-Reingold style pseudorandom functions, and auxiliary input secure encryption. This can be seen as an alternative to the known family of k -LIN assumptions.","Title: Implementing AES via an actively/covertly secure dishonest-majority MPC protocol\nYear: 2012\n\nAbstract: We describe an implementation of the protocol of Damgård, Pastro, Smart and Zakarias (SPDZ/Speedz) for multi-party computation in the presence of a dishonest majority of active adversaries. We present a number of modifications to the protocol; the first reduces the security to covert security, but produces significant performance enhancements; the second enables us to perform bit-wise operations in characteristic two fields. As a bench mark application we present the evaluation of the AES cipher, a now standard bench marking example for multi-party computation. We need examine two different implementation techniques, which are distinct from prior MPC work in this area due to the use of MACs within the SPDZ protocol. We then examine two implementation choices for the finite fields; one based on finite fields of size 28 and one based on embedding the AES field into a larger finite field of size 240.","Title: Zero-Knowledge Authentication Scheme with Secret Key Exchange (Extended Abstract)\nYear: 1988\n\nAbstract: In this note we first develop a new computationally zero-knowledge interactive proof system of knowledge, which then is modified\n into an authentication scheme with secret key exchange for subsequent conventional encryption. Implemented on a standard 32-bit\n chip or similar, the whole protocol, which involves mutual identification of two users, exchange of a random common secret\n key and verification of certificates for the public keys (RSA, 512 bits) takes less than 0.7 seconds.","Title: Universally Composable Multiparty Computation with Partially Isolated Parties\nYear: 2007\n\nAbstract: It is well known that universally composable multiparty computation cannot, in general, be achieved in the standard model without setup assumptions when the adversary can corrupt an arbitrary number of players. One way to get around this problem is by having a trusted third party generate some global setup such as a common reference string (CRS) or a public key infrastructure (PKI) . The recent work of Katz shows that we may instead rely on physical assumptions, and in particular tamper-proof hardware tokens . In this paper, we consider a similar but strictly weaker physical assumption. We assume that a player (Alice) can partially isolate another player (Bob) for a brief portion of the computation and prevent Bob from communicating more than some limited number of bits with the environment. For example, isolation might be achieved by asking Bob to put his functionality on a tamper-proof hardware token and assuming that Alice can prevent this token from communicating to the outside world. Alternatively, Alice may interact with Bob directly but in a special office which she administers and where there are no high-bandwidth communication channels to the outside world. We show that, under standard cryptographic assumptions, such physical setup can be used to UC-realize any two party and multiparty computation in the presence of an active and adaptive adversary corrupting any number of players. We also consider an alternative scenario, in which there are some trusted third parties but no single such party is trusted by all of the players. This compromise allows us to significantly limit the use of the physical set-up and hence might be preferred in practice.","Title: Bounded Tamper Resilience: How to go beyond the Algebraic Barrier.\nYear: 2013\n\nAbstract: Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary in case of arbitrary key relations, as otherwise a generic attack of Gennaro et al. (TCC 2004) shows how to recover the key of almost any cryptographic primitive. We describe our contributions in more detail below. (1) We show that standard ID and signature schemes constructed from a large class of $$\\\\Sigma $$Σ-protocols (including the Okamoto scheme, for instance) are secure even if the adversary can arbitrarily tamper with the prover's state a bounded number of times and obtain some bounded amount of leakage. Interestingly, for the Okamoto scheme we can allow also independent tampering with the public parameters. (2) We show a bounded tamper and leakage resilient CCA-secure public key cryptosystem based on the DDH assumption. We first define a weaker CCA-like security notion that we can instantiate based on DDH, and then we give a general compiler that yields CCA security with tamper and leakage resilience. This requires a public tamper-proof common reference string. (3) Finally, we explain how to boost bounded tampering and leakage resilience [as in (1) and (2) above] to continuous tampering and leakage resilience, in the so-called floppy model where each user has a personal hardware token (containing leak- and tamper-free information) which can be used to refresh the secret key. We believe that bounded tampering is a meaningful and interesting alternative to avoid known impossibility results and can provide important insights into the security of existing standard cryptographic schemes.","Title: Multiparty Computation from Somewhat Homomorphic Encryption.\nYear: 2011\n\nAbstract: We propose a general multiparty computation protocol secure against an active adversary corrupting up to n-1 of the n players. The protocol may be used to compute securely arithmetic circuits over any finite field F.. Our protocol consists of a preprocessing phase that is both independent of the function to be computed and of the inputs, and a much more efficient online phase where the actual computation takes place. The online phase is unconditionally secure and has total computational (and communication) complexity linear in n, the number of players, where earlier work was quadratic in n. Moreover, the work done by each player is only a small constant factor larger than what one would need to compute the circuit in the clear. We show this is optimal for computation in large fields. In practice, for 3 players, a secure 64-bit multiplication can be done in 0.05 ms. Our preprocessing is based on a somewhat homomorphic cryptosystem. We extend a scheme by Brakerski et al., so that we can perform distributed decryption and handle many values in parallel in one ciphertext. The computational complexity of our preprocessing phase is dominated by the public-key operations, we need O(n(2)/s) operations per secure multiplication where s is a parameter that increases with the security parameter of the cryptosystem. Earlier work in this model needed Omega(n(2)) operations. In practice, the preprocessing prepares a secure 64-bit multiplication for 3 players in about 13 ms.","Title: Multiparty Computation from Threshold Homomorphic Encryption\nYear: 2001\n\nAbstract: We introduce a new approach to multiparty computation (MPC) basing it on homomorphic threshold crypto-systems. We show that given keys for any sufficiently efficient system of this type, general MPC protocols for n parties can be devised which are secure against an active adversary that corrupts any minority of the parties. The total number of bits broadcast is O(nk|C|), where k is the security parameter and |C| is the size of a (Boolean) circuit computing the function to be securely evaluated. An earlier proposal by Franklin and Haber with the same complexity was only secure for passive adversaries, while all earlier protocols with active security had complexity at least quadratic in n. We give two examples of threshold cryptosystems that can support our construction and lead to the claimed complexities.","Title: Secret-Key Zero-Knowlegde and Non-interactive Verifiable Exponentiation\nYear: 2004\n\nAbstract: We consider a new model for non-interactive zero-knowledge where security is not based on a common reference string, but where prover and verifier are assumed to possess appropriately correlated secret keys. We present efficient proofs for equality of discrete logarithms in this model with unconditional soundness and zero-knowledge. This has immediate applications to non-interactive verification of undeniable signatures and pseudorandom function values. Another application is the following: a set of 1 servers, of which less than l/2 are corrupt, hold shares of a secret integer s. A client C specifies g in some finite group G, and the servers want to allow the client to compute g(s) non-interactively, i.e., by sending information to C only once. This has immediate applications in threshold cryptography. Using our proof system, the problem can be solved as efficiently as the fastest previous solutions that either required interaction or had to rely on the random oracle model for a proof of security. The price we pay is the need to establish the secret key material once and for all. We present an alternative solution to the problem that is also non-interactive and where clients need no secret keys. This comes at the expense of more communication and the assumption that less than l/3 of the servers are corrupt.","Title: New Generation of Secure and Practical RSA-Based Signatures\nYear: 1996\n\nAbstract: For most digital signature schemes used in practice, such as ISO9796/RSA or DSA, it has only been shown that certain plausible cryptographic assumptions, such as the difficulty of factoring integers, computing discrete logarithms or the collision-intractability of certain hash-functions are necessary for the security of the scheme, while their sufficiency is, strictly speaking, an open question. A clear advantage of such schemes over many signature schemes with security proven relative to such common cryptographic assumptions, is their efficiency: as a result of their relatively weak requirements regarding computation, bandwidth and storage, these schemes have so far beaten proven secure schemes in practice. Our aim is to contribute to the bridging of the gap that seems to exist between the theory and practice of digital signature schemes. We present a digital signature that offers both proven security and practical value. More precisely, under an appropriate assumption about RSA, the scheme is proven to be not existentially forgeable under adaptively chosen message attacks. We also identify some applications where our scheme can be conveniently implemented using dedicated smartcards that are available today.","Title: A Generalisation, a Simplification and Some Applications of Paillier's Probabilistic Public-Key System\nYear: 2001\n\nAbstract: We propose a generalisation of Paillier's probabilistic public key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without loosing the homomorphic property. We show that the generalisation is as secure as Paillier's original system. We construct a threshold variant of the generalised scheme as well as zero-knowledge protocols to show that a given ciphertext encrypts one of a set of given plaintexts, and protocols to verify multiplicative relations on plaintexts. We then show how these building blocks can be used for applying the scheme to efficient electronic voting.This reduces dramatically the work needed to compute the final result of an election, compared to the previously best known schemes.W e show how the basic scheme for a yes/no vote can be easily adapted to casting a vote for up to t out of L candidates. The same basic building blocks can also be adapted to provide receipt-free elections, under appropriate physical assumptions. The scheme for 1 out of L elections can be optimised such that for a certain range of parameter values, a ballot has size only O(log L) bits.","Title: Multiparty Computations Ensuring Privacy of Each Party's Input and Correctness of the Result\nYear: 1987\n\nAbstract: A protocol is presented that allows a set of parties to collectively perform any agreed computation, where every party is able to choose secret inputs and verify that the resulting output is correct, and where all secret inputs are optimally protected. The protocol has the following properties: 驴 One participant is allowed to hide his secrets unconditionally, i.e. the protocol releases no Shannon information about these secrets. This means that a participant with bounded resources can perform computations securely with a participant who may have unlimited computing power. To the best of our knowledge, our protocol is the first of its kind to provide this possibility. 驴 The cost of our protocol is linear in the number of gates in a circuit performing the computation, and in the number of participants. We believe it is conceptually simpler and more efficient than other protocols solving related problems ([Y1], [GoMiWi] and [GaHaYu]). It therefore leads to practical solutions of problems involving small circuits. 驴 The protocol is openly verifiable, i.e. any number of people can later come in and rechallenge any participant to verify that no cheating has occurred. 驴 The protocol is optimally secure against conspiracies: even if n - 1 out of the n participants collude, they will not find out more about the remaining participants' secrets than what they could already infer from their own input and the public output. 驴 Each participant has a chance of undetected cheating that is only exponentially small in the amount of time and space needed for the protocol. 驴 The protocol adapts easily, and with negligible extra cost, to various additional requirements, e.g. making part of the output private to some participant, ensuring that the participants learn the output simultaneously, etc. 驴 Participants can prove relations between data used in different instances of the protocol, even if those instances involve different groups of participants. For example, it can be proved that the output of one computation was used as input to another, without revealing more about this data. 驴 The protocol can be usen as an essential tool in proving that all languages in IP have zero knowledge proof systems, i.e. any statement which can be proved interactively can also be proved in zero knowledge.The rest of this paper is organised as follows: First we survey some related results. Then Section 2 gives an intuitive introduction to the protocol. In Section 3, we present one of the main tools used in this paper: bit commitment schemes. Sections 4 and 5 contain the notation, terrninology, etc. used in the paper. In Section 6, the protocol is presented, along with proofs of its security and correctness. In Section 7, we show how to adapt the protocol to various extra requirements and discuss some generalisations and optimisations. Finally, Section 8 contains some remarks on how to construct zero knowledge proof systems for any language in IP.","Title: Interactive Hashing can Simplify Zero-Knowledge Protocol Design Without Computational Assumptions (Extended Abstract)\nYear: 1993\n\nAbstract: We show that any 3-round protocol (in general, any bounded round protocol) in which the verifier sends only random bits, and which is zero-knowledge against an honest verifier can be transformed into a protocol that is zero-knowledge in general. The transformation is based on the interactive hashing technique of Naor, Ostrovsky, Venkatesan and Yung. No assumption is made on the computing power of prover or verifier, and the transformation therefore is valid in both the proof and argument model, and does not rely on any computational assumptions such as the existence of one-way permutations. The technique is also applicable to proofs of knowledge. The transformation preserves perfect and statistical zero-knowledge. As corollaries, we show first a generalization of a result by Damg氓rd on construction of bit-commitments from zero-knowledge proofs. Other corollaries give results on noninteractive zero-knowledge, one-sided proof systems, and black-box simulation.","Title: Threshold decryption and zero-knowledge proofs for lattice-based cryptosystems\nYear: 2010\n\nAbstract: We present a variant of Regev’s cryptosystem first presented in [Reg05], but with a new choice of parameters. By a recent classical reduction by Peikert we prove the scheme semantically secure based on the worst-case lattice problem GapSVP. From this we construct a threshold cryptosystem which has a very efficient and non-interactive decryption protocol. We prove the threshold cryptosystem secure against passive adversaries corrupting all but one of the players, and againts active adversaries corrupting less than one third of the players. We also describe how one can build a distributed key generation protocol. In the final part of the paper we show how one can, in zero-knowledge - prove knowledge of the plaintext contained in a given ciphertext from Regev’s original cryptosystem or our variant. The proof is of size only a constant times the size of the public key.","Title: On the Amortized Complexity of Zero-Knowledge Protocols\nYear: 2014\n\nAbstract: We propose a general technique that allows improving the complexity of zero-knowledge protocols for a large class of problems where previously the best known solution was a simple cut-and-choose style protocol, i.e., where the size of a proof for problem instance x and error probability 2 n was O (| x | n ) bits. By using our technique to prove n instances simultaneously, we can bring down the proof size per instance to O (| x |+ n ) bits for the same error probability while using no computational assumptions. Examples where our technique applies include proofs for quadratic residuosity, proofs of subgroup membership and knowledge of discrete logarithms in groups of unknown order, interval proofs of the latter, and proofs of plaintext knowledge for various types of homomorphic encryption schemes. We first propose our protocols as Σ -protocols and extend them later to zero-knowledge proofs of knowledge.","Title: Constant-round multiparty computation using a black-box pseudorandom generator\nYear: 2005\n\nAbstract: We present a constant-round protocol for general secure multiparty computation which makes a black-box use of a pseudorandom generator. In particular, the protocol does not require expensive zero-knowledge proofs and its communication complexity does not depend on the computational complexity of the underlying cryptographic primitive. Our protocol withstands an active, adaptive adversary corrupting a minority of the parties. Previous constant-round protocols of this type were only known in the semi-honest model or for restricted classes of functionalities.","Title: Improved Non-committing Encryption Schemes Based on a General Complexity Assumption\nYear: 2000\n\nAbstract: Non-committing encryption enables the construction of multiparty computation protocols secure against an adaptive adversary in the computational setting where private channels between players are not assumed. While any non-committing encryption scheme must be secure in the ordinary semantic sense, the converse is not necessarily true. We propose a construction of non-committing encryption that can be based on any public-key system which is secure in the ordinary sense and which has an extra property we call simulatability. This generalises an earlier scheme proposed by Beaver based on the Diffie-Hellman problem, and we propose another implementation based on RSA. In a more general setting, our construction can be based on any collection of trapdoor permutations with a certain simulatability property. This offers a considerable efficiency improvement over the first non-committing encryption scheme proposed by Canetti et al. Finally, at some loss of efficiency, our scheme can be based on general collections of trapdoor permutations without the simulatability assumption, and without the common-domain assumption of Canetti et al. In showing this last result, we identify and correct a bug in a key generation protocol from Canetti et al.","Title: Simplified threshold RSA with adaptive and proactive security\nYear: 2006\n\nAbstract: We present the currently simplest, most efficient, optimally resilient, adaptively secure, and proactive threshold RSA scheme. A main technical contribution is a new rewinding strategy for analysing threshold signature schemes. This new rewinding strategy allows to prove adaptive security of a proactive threshold signature scheme which was previously assumed to be only statically secure. As a separate contribution we prove that our protocol is secure in the UC framework.","Title: From passive to covert security at low cost\nYear: 2010\n\nAbstract: Aumann and Lindell defined security against covert attacks, where the adversary is malicious, but is only caught cheating with a certain probability. The idea is that in many real-world cases, a large probability of being caught is sufficient to prevent the adversary from trying to cheat. In this paper, we show how to compile a passively secure protocol for honest majority into one that is secure against covert attacks, again for honest majority and catches cheating with probability 1/4. The cost of the modified protocol is essentially twice that of the original plus an overhead that only depends on the number of inputs.","Title: On the Theory and Practice of Personal Digital Signatures\nYear: 2009\n\nAbstract: We take a step towards a more realistic modeling of personal digital signatures, where a human user, his mobile equipment, his PC and a server are all considered as independent players in the protocol, and where only the human user is assumed incorruptible. We then propose a protocol for issuing digital signatures on behalf of the user. This protocol is proactively UC-secure assuming at most one player is corrupted in every operational phase. In more practical terms, this means that one can securely sign using terminals (PC's) that are not necessarily trusted, as long as the mobile unit and the PC are not both corrupted at the same time. In other words, our solution cannot be broken by phising or key-logging via the PC. The protocol allows for mobile units with very small computing power by securely outsourcing computation to the PC and also allows usage of any PC that can communicate properly. Finally, we report on the results of a prototype implementation of our solution.","Title: Efficient and Provable Security Amplifications\nYear: 1996\n\nAbstract: Even, Goldreich and Micali showed at Crypto''89 that the existence of signature schemes secure against known message attacks implies the existence of schemes secure against adaptively chosen message attacks. Unfortunately, this transformation leads to a rather impractical scheme. We exhibit a similar security amplification, which takes the given scheme to a new signature scheme that is not even existentially forgeable under adaptively chosen message attacks. Additionally, however, our transformation will be practical: The complexity of the resulting scheme is twice that of the original scheme. The principles of both transformations carry over to block encryption systems. It is shown how they can be used to convert a block encryption system secure against known plaintext attacks to a system secure against chosen plaintext attacks. For both schemes it is shown that if the transformed scheme can be broken given a number, $T$, of encryptions of adaptively chosen plaintexts, then the original scheme can be broken given encryptions of $T$ uniformly chosen plaintexts. In this case, however, the application of the technique of Even, Goldreich and Micali leads to the more efficient scheme. The transformed scheme has the same key length as the original, and ciphertexts are doubled in length. As an example, when applied to DES the transformed scheme is secure against differential cryptanalysis, which relies on the ability to get encryptions of plaintext pairs with proper differences.","Title: Perfectly secure multiparty computation and the computational overhead of cryptography\nYear: 2010\n\nAbstract: We study the following two related questions: What are the minimal computational resources required for general secure multiparty computation in the presence of an honest majority? What are the minimal resources required for two-party primitives such as zero-knowledge proofs and general secure two-party computation? We obtain a nearly tight answer to the first question by presenting a perfectly secure protocol which allows n players to evaluate an arithmetic circuit of size s by performing a total of $\\mathcal{O}(s\\log s\\log^2 n)$ arithmetic operations, plus an additive term which depends (polynomially) on n and the circuit depth, but only logarithmically on s. Thus, for typical large-scale computations whose circuit width is much bigger than their depth and the number of players, the amortized overhead is just polylogarithmic in n and s. The protocol provides perfect security with guaranteed output delivery in the presence of an active, adaptive adversary corrupting a (1/3−ε) fraction of the players, for an arbitrary constant ε0 and sufficiently large n. The best previous protocols in this setting could only offer computational security with a computational overhead of poly(k,logn,logs), where k is a computational security parameter, or perfect security with a computational overhead of $\\mathcal{O}(n\\log n)$. We then apply the above result towards making progress on the second question. Concretely, under standard cryptographic assumptions, we obtain zero-knowledge proofs for circuit satisfiability with 2−k soundness error in which the amortized computational overhead per gate is only polylogarithmic in k, improving over the ω(k) overhead of the best previous protocols. Under stronger cryptographic assumptions, we obtain similar results for general secure two-party computation.","Title: Efficient Zero-Knowledge Proofs of Knowledge Without Intractability Assumptions\nYear: 2000\n\nAbstract: . We initiate the investigation of the class of relations that admit extremely efficient perfectzero knowledge proofs of knowledge: constant number of rounds, communication linear in the length ofthe statement and the witness, and negligible knowledge error. In its most general incarnation, our resultsays that for relations that have a particular three-move honest-verifier zero-knowledge (HVZK) proofof knowledge, and which admit a particular three-move HVZK proof of knowledge for an...","Title: Share conversion, pseudorandom secret-sharing and applications to secure computation\nYear: 2005\n\nAbstract: We present a method for converting shares of a secret into shares of the same secret in a different secret-sharing scheme using only local computation and no communication between players. In particular, shares in a replicated scheme based on a CNF representation of the access structure can be converted into shares from any linear scheme for the same structure. We show how this can be combined with any pseudorandom function to create, from initially distributed randomness, any number of Shamir secret-sharings of (pseudo)random values without communication. We apply this technique to obtain efficient non-interactiveprotocols for secure computation of low-degree polynomials, which in turn give rise to other applications in secure computation and threshold cryptography. For instance, we can make the Cramer-Shoup threshold cryptosystem by Canetti and Goldwasser fully non-interactive, or construct non-interactive threshold signature schemes secure without random oracles. The latter solutions are practical only for a relatively small number of players. However, in our main applications the number of players is typically small, and furthermore it can be argued that no solution that makes a black-box use of a pseudorandom function can be more efficient.","Title: How to Split a Shared Secret into Shared Bits in Constant-Round\nYear: 2005\n\nAbstract: We show that if a set of players hold shares of a value a ∈ Zp for some prime p (where the set of shares is written (a)p), it is possible to compute, in constant round and with unconditional security, sharings of the bits of a, i.e. compute sharings (a0)p, . . . ,(aℓ 1)p such","Title: Multiple Encryption with Minimum Key\nYear: 1995\n\nAbstract: In this paper we consider multiple encryption schemes built from conventional cryptosystems such as DES. The existing schemes are either vulnerable to variants of meet in the middle attacks, i.e. they do not provide security of the full key or there is no proof that the schemes are as secure as the underlying cipher. We propose a new variant of two-key triple encryption which is not vulnerable to the meet in the middle attack and which uses a minimum amount of key. We can prove a connection between the security of our system and the security of the underlying block cipher.","Title: On the amortized complexity of zero knowledge protocols for multiplicative relations\nYear: 2012\n\nAbstract: We present a protocol that allows to prove in zero-knowledge that committed values xi, yi, zi, i=1,…,l satisfy xiyi=zi, where the values are taken from a finite field. For error probability 2−u the size of the proof is linear in u and only logarithmic in l. Therefore, for any fixed error probability, the amortized complexity vanishes as we increase l. In particular, when the committed values are from a field of small constant size, we improve complexity of previous solutions by a factor of l. Assuming preprocessing, we can make the commitments (and hence the protocol itself) be information theoretically secure. Using this type of commitments we obtain, in the preprocessing model, a perfect zero-knowledge interactive proof for circuit satisfiability of circuit C where the proof has size O(|C|). We then generalize our basic scheme to a protocol that verifies l instances of an algebraic circuit D over K with v inputs, in the following sense: given committed values xi,j and zi, with i=1,…,l and j=1,…,v, the prover shows that D(xi,1,…,xi,v)=zi for i=1,…,l. The interesting property is that the amortized complexity of verifying one circuit only depends on the multiplicative depth of the circuit and not the size. So for circuits with small multiplicative depth, the amortized cost can be asymptotically smaller than the number of multiplications in D. Finally we look at commitments to integers, and we show how to implement information theoretically secure homomorphic commitments to integer values, based on preprocessing. After preprocessing, they require only a constant number of multiplications per commitment. We also show a variant of our basic protocol, which can verify l integer multiplications with low amortized complexity. This protocol also works for standard computationally secure commitments and in this case we improve on security: whereas previous solutions with similar efficiency require the strong RSA assumption, we only need the assumption required by the commitment scheme itself, namely factoring.","Title: Theory and practice of multiparty computation\nYear: 2006\n\nAbstract: This is a short summary of the invited talk given by the author at the SCN conference.","Title: New convertible undeniable signature schemes\nYear: 1996\n\nAbstract: Undeniable signatures are like ordinary digital signatures, except that testing validity of a signature requires interaction with the signer. This gives the signer additional control over who will benefit from being convinced by a signature, and is particularly relevant when signing sensitive, non-public data. Convertible undeniable signatures offer additional flexibility in that there is a separate verification key that can be used to verify a signature (without interaction). This allows the signer to delegate the ability to verify signatures to one or more participants, and ultimately to convert all signatures to ordinary ones by making the verification key public. While provably secure theoretical solutions exist for convertible schemes, earlier practical schemes proposed have either been broken or their status as far as security is concerned is very unclear. In this paper, we present two new convertible schemes, in which forging signatures is provably equivalent to forging El Gamal signatures. The difficulty of verifying signatures without interacting with the signer is based on the factoring problem for one of the schemes and on the Diffie-Hellman problem for the other scheme.","Title: Multiparty Unconditionally Secure Protocols (Abstract)\nYear: 1987\n\nAbstract: It has been shown previously how almost any multiparty protocol problem can be solved. All the constructions suggested so far rely on trapdoor one-way functions, and therefore must assume essentially that public key cryptography is possible. It has also been shown that unconditional protection of a single designated participant is all that can be achieved under that model. Assuming only authenticated secrecy channels between pairs of participants, we show that essentially any multiparty protocol problem can be solved. Such a model actually implies the further requirement that less than one third of the participants deviate from the protocol. The techniques presented do not, however, rely on any cryptographic assumptions; they achieve the optimal result and provide security as good as the secrecy and authentication of the channeis used. Moreover, the constructions have a built-in fault tolerance: once the participants have sent messages committing themselves to the secrets they will use in the protocol, there is no way less than a third of them can stop the protocol from completing correctly. Our technique relies on the so called key-safeguarding or secret-sharing schemes proposed by Blakley and Shamir as basic building blocks. The usefulness of their homomorphic structure was observed by Benaloh, who proposed techniques very similar to ours.","Title: Secure two-party computation with low communication\nYear: 2012\n\nAbstract: We propose a 2-party UC-secure protocol that can compute any function securely. The protocol requires only two messages, communication that is poly-logarithmic in the size of the circuit description of the function, and the workload for one of the parties is also only poly-logarithmic in the size of the circuit. This implies, for instance, delegatable computation that requires no expensive off-line phase and remains secure even if the server learns whether the client accepts its results. To achieve this, we define two new notions of extractable hash functions, propose an instantiation based on the knowledge of exponent in an RSA group, and build succinct zero-knowledge arguments in the CRS model.","Title: Linear integer secret sharing and distributed exponentiation\nYear: 2006\n\nAbstract: We introduce the notion of Linear Integer Secret-Sharing (LISS) schemes, and show constructions of such schemes for any access structure. We show that any LISS scheme can be used to build a secure distributed protocol for exponentiation in any group. This implies, for instance, distributed RSA protocols for arbitrary access structures and with arbitrary public exponents.","Title: Scalable Multiparty Computation with Nearly Optimal Work and Resilience\nYear: 2008\n\nAbstract: We present the first general protocol for secure multiparty computation in which the totalamount of work required by nplayers to compute a function fgrows only polylogarithmically with n(ignoring an additive term that depends on nbut not on the complexity of f). Moreover, the protocol is also nearly optimal in terms of resilience, providing computational security against an active, adaptive adversary corrupting a (1/2 茂戮驴 茂戮驴) fraction of the players, for an arbitrary 茂戮驴 0.","Title: Efficient algorithms for the gcd and cubic residuosity in the ring of Eisenstein integers\nYear: 2003\n\nAbstract: We present simple and efficient algorithms for computing the gcd and cubic residuosity in the ring of Eisenstein integers, Z[@z], i.e. the integers extended with @z, a complex primitive third root of unity. The algorithms are similar and may be seen as generalisations of the binary integer gcd and derived Jacobi symbol algorithms. Our algorithms take time O(n^2) for n-bit input. For the cubic residuosity problem this is an improvement from the known results based on the Euclidean algorithm, and taking time O(n@?M(n)), where M(n) denotes the complexity of multiplying n-bit integers. For the gcd problem our algorithm is simpler and faster than an earlier algorithm of complexity O(n^2). The new algorithms have applications in practical primality tests and the implementation of cryptographic protocols.","Title: Quantum Communication Attacks on Classical Cryptographic Protocols - (Invited Talk)\nYear: 2011\n\nAbstract: In the literature on cryptographic protocols, it has been studied several times what happens if a classical protocol is attacked\n by a quantum adversary. Usually, this is taken to mean that the adversary runs a quantum algorithm, but communicates classically\n with the honest players. In several cases, one can show that the protocol remains secure even under such an attack.\n \n \n However, there are also cases where the honest players are quantum as well, even if the protocol uses classical communication.\n For instance, this is the case when classical multiparty computation is used as a “subroutine” in quantum multiparty computation.\n Furthermore, in the future, players in a protocol may employ quantum computing simply to improve efficiency of their local\n computation, even if the communication is supposed to be classical. In such cases, it no longer seems clear that a quantum\n adversary must be limited to only classical communication with the honest players. And so the natural question is: what happens\n to the security if this limitation is dropped?\n \n \n \n In this talk, we survey some results from ongoing work that addresses this question, more specifically, we consider security\n of secret sharing, zero-knowledge protocols and multiparty computation under this new paradigm. In all cases, both positive\n and negative results can be shown. For instance, a classical threshold secret sharing scheme designed for threshold t is no longer secure in this model, but the same scheme is secure with threshold t/2.\n \n \n \n This is joint work with Jakob Funder, Jesper Buus Nielsen (Dept. of Computer Science, Aarhus University) and Louis Salvail\n (Université de Montréal).","Title: Quantum-Secure Coin-Flipping and Applications\nYear: 2009\n\nAbstract: In this paper, we prove classical coin-flipping secure in the presence of quantum adversaries. The proof uses a recent result of Watrous [20] that allows quantum rewinding for protocols of a certain form. We then discuss two applications. First, the combination of coin-flipping with any non-interactive zero-knowledge protocol leads to an easy transformation from non-interactive zero-knowledge to interactive quantum zero-knowledge. Second, we discuss how our protocol can be applied to a recently proposed method for improving the security of quantum protocols [4], resulting in an implementation without set-up assumptions. Finally, we sketch how to achieve efficient simulation for an extended construction in the common-reference-string model.","Title: Non-interactive zero-knowledge from homomorphic encryption\nYear: 2006\n\nAbstract: We propose a method for compiling a class of Σ-protocols (3-move public-coin protocols) into non-interactive zero-knowledge arguments. The method is based on homomorphic encryption and does not use random oracles. It only requires that a private/public key pair is set up for the verifier. The method applies to all known discrete-log based Σ-protocols. As applications, we obtain non-interactive threshold RSA without random oracles, and non-interactive zero-knowledge for NP more efficiently than by previous methods.","Title: Public-key encryption with non-interactive opening\nYear: 2008\n\nAbstract: We formally define the primitive of public-key encryption with non-interactive opening (PKENO), where the receiver of a cipher-text C can, convincingly and without interaction, reveal what the result was of decrypting C, without compromising the scheme's security. This has numerous applications in cryptographic protocol design, e.g., when the receiver wants to demonstrate that some information he was sent privately was not correctly formed. We give a definition based on the UC framework as well as an equivalent game-based definition. The PKENO concept was informally introduced by Damgård and Thorbek who suggested that it could be implemented based on Identity-Based Encryption. In this paper, we give direct and optimized implementations, that work without having to keep state information, unlike what one obtains from directly using IBE.","Title: Multiparty computation for dishonest majority: from passive to active security at low cost\nYear: 2010\n\nAbstract: Multiparty computation protocols have been known for more than twenty years now, but due to their lack of efficiency their use is still limited in real-world applications: the goal of this paper is the design of efficient two and multi party computation protocols aimed to fill the gap between theory and practice. We propose a new protocol to securely evaluate reactive arithmetic circuits, that offers security against an active adversary in the universally composable security framework. Instead of the \"do-and-compile\" approach (where the parties use zero-knowledge proofs to show that they are following the protocol) our key ingredient is an efficient version of the \"cut-and-choose\" technique, that allow us to achieve active security for just a (small) constant amount of work more than for passive security.","Title: An Integer Commitment Scheme based on Groups with Hidden Order.\nYear: 2001\n\nAbstract: Abstract. We present a commitment,scheme allowing commitment,to arbitrary size integers, based on any Abelian group with certain properties, most importantly that it is hard for the committer to compute its order. Potential examples include RSA and class groups. We also give efficient zero-knowledge protocols for proving knowledge ofthe contents of a commitment,and for verifying multiplicative relations over the integers on committed values. This means that our scheme can support, for instance, the efficent interval proofs of Boudot[1]. The scheme can be seen as a modification and a generalization of an earlier scheme,of Fujisaki and Okamoto [5], and in particular our results show that we can use a much,larger class of RSA moduli than the safe prime products proposed in [5]. Also, we correct some mistakes in the proofs of [5] and give what appears to be the first multiplication protocol for a Fujisaki/Okamoto-like scheme with a complete proof of soundness.","Title: Secure protocols with asymmetric trust\nYear: 2007\n\nAbstract: In the standard general-adversary model for multi-party protocols, a global adversary structure is given, and every party must trust in this particular structure. We introduce a more general model, the asymmetric-trust model, wherein every party is allowed to trust in a different, personally customized adversary structure. We have two main contributions. First, we present non-trivial lower and upper bounds for broadcast, verifiable secret sharing, and general multi-party computation in different variations of this new model. The obtained bounds demonstrate that the new model is strictly more powerful than the standard general-adversary model. Second, we propose a framework for expressing and analyzing asymmetric trust in the usual simulation paradigm for defining security of protocols, and in particular show a general composition theorem for protocols with asymmetric trust.","Title: Perfect Hiding and Perfect Binding Universally Composable Commitment Schemes with Constant Expansion Factor\nYear: 2001\n\nAbstract: Canetti and Fischlin have recently proposed the security notion universal composability for commitment schemes and provided two examples. This new notion is very strong. It guarantees that security is maintained even when an unbounded number of copies of the scheme are running concurrently, also it guarantees non-malleability and security against adaptive adversaries. Both proposed schemes use 驴(k) bits to commit to one bit and can be based on the existence of trapdoor commitments and non-malleable encryption.We present new universally composable commitment (UCC) schemes based on extractable q one-way homomorphisms. These in turn exist based on the Paillier cryptosystem, the Okamoto-Uchiyama cryptosystem, or the DDH assumption. The schemes are efficient: to commit to k bits, they use a constant number of modular exponentiations and communicates O(k) bits. Furthermore the scheme can be instantiated in either perfectly hiding or perfectly binding versions. These are the first schemes to show that constant expansion factor, perfect hiding, and perfect binding can be obtained for universally composable commitments.We also show how the schemes can be applied to do efficient zero-knowledge proofs of knowledge that are universally composable.","Title: Short Non-Interactive Cryptographic Proofs\nYear: 2000\n\nAbstract: We show how to produce short proofs of theorems such that a distrusting Verifier can be convinced that the theorem is true yet obtains no information about the proof itself. We assume the theorem is represented by a boolean circuit, of size m gates, which is satisfiable if and only if the theorem holds. We use bit commitments of size k and bound the probability of false proofs going undetected by 2 r . We obtain non-interactive zero-knowledge proofs of size O(mk(log m + r)) bits. In the random...","Title: Speeding up Prime Number Generation\nYear: 1991\n\nAbstract: We present various ways of speeding up the standard methods for generating provable, resp. probable primes. For probable primes, the effect of using test division and 2 as a fixed base for the Rabin test is analysed, showing that a speedup of almost 50% can be achieved with the same confidence level, compared to the standard method. For Maurer's algorithm generating provable primes p, we show that a small extension of the algorithm will mean that only one prime factor of p–1 has to be generated, implying a gain in efficiency. Further savings can be obtained by combining with the Rabin test. Finally, we show how to combine the algorithms of Maurer and Gordon to make strong provable primes that satisfy additional security constraints.","Title: Sequential Iteration of Interactive Arguments and an Efficient Zero-Knowledge Argument for NP\nYear: 1998\n\nAbstract: We study interactive arguments, in particular their error probability under sequential iteration. This problem is more complex\n than for interactive proofs, where the error trivially decreases exponentially in the number of iterations.\n \n In particular, we study the typical efficient case where the iterated protocol is based on a single instance of a computational\n problem. This is not a special case of independent iterations of an entire protocol, and real exponential decrease of the\n error cannot be expected. Nevertheless, for practical applications, one needs concrete relations between the complexity and\n error probability of the underlying problem and the iterated protocol. We formalize and solve this problem using the theory\n of proofs of knowledge. We also seem to present the first definition of arguments in a fully uniform model of complexity.\n \n \n \n We also prove that in non-uniform complexity, the error probability of independent iterations of an argument does decrease\n exponentially — to our knowledge this is the first result about a strictly exponentially small error probability in a computational\n cryptographic security property.\n \n \n \n To illustrate our first result, we present a very efficient zero-knowledge argument for circuit satisfiability, and thus for\n any NP problem, based on any collision-intractable hash function.","Title: On the necessary and sufficient assumptions for UC computation\nYear: 2010\n\nAbstract: We study the necessary and sufficient assumptions for universally composable (UC) computation, both in terms of setup and computational assumptions. We look at the common reference string model, the uniform random string model and the key-registration authority model (KRA), and provide new results for all of them. Perhaps most interestingly we show that: For even the minimal meaningful KRA, where we only assume that the secret key is a value which is hard to compute from the public key, one can UC securely compute any poly-time functionality if there exists a passive secure oblivious-transfer protocol for the stand-alone model. Since a KRA where the secret keys can be computed from the public keys is useless, and some setup assumption is needed for UC secure computation, this establishes the best we could hope for the KRA model: any non-trivial KRA is sufficient for UC computation. We show that in the KRA model one-way functions are sufficient for UC commitment and UC zero-knowledge. These are the first examples of UC secure protocols for non-trivial tasks which do not assume the existence of public-key primitives. In particular, the protocols show that non-trivial UC computation is possible in Minicrypt.","Title: Efficient threshold RSA signatures with general moduli and no extra assumptions\nYear: 2005\n\nAbstract: We propose techniques that allow construction of robust threshold RSA signature schemes that can work without a trusted dealer using known key generation protocols and is as efficient as the best previous schemes. We do not need special conditions on the RSA modulus, extra complexity or set-up assumptions or random oracles. An “optimistic” variant of the scheme is even more efficient in case no faults occur. Some potential more general applications of our basic idea are also pointed out.","Title: Universally Composable Symbolic Analysis for Two-Party Protocols based on Homomorphic Encryption.\nYear: 2014\n\nAbstract: We consider a class of two-party function evaluation protocols in which the parties are allowed to use ideal functionalities as well as a set of powerful primitives, namely commitments, homomorphic encryption, and certain zero-knowledge proofs. With these it is possible to capture protocols for oblivious transfer, coin-flipping, and generation of multiplication-triples. We show how any protocol in our class can be compiled to a symbolic representation expressed as a process in an abstract process calculus, and prove a general computational soundness theorem implying that if the protocol realises a given ideal functionality in the symbolic setting, then the original version also realises the ideal functionality in the standard computational UC setting. In other words, the theorem allows us to transfer a proof in the abstract symbolic setting to a proof in the standard UC model. Finally, we have verified that the symbolic interpretation is simple enough in a number of cases for the symbolic proof to be partly automated using the ProVerif tool.","Title: Semi-homomorphic encryption and multiparty computation\nYear: 2011\n\nAbstract: An additively-homomorphic encryption scheme enables us to compute linear functions of an encrypted input by manipulating only the ciphertexts. We define the relaxed notion of a semi-homomorphic encryption scheme, where the plaintext can be recovered as long as the computed function does not increase the size of the input \"too much\". We show that a number of existing cryptosystems are captured by our relaxed notion. In particular, we give examples of semi-homomorphic encryption schemes based on lattices, subset sum and factoring. We then demonstrate how semi-homomorphic encryption schemes allow us to construct an efficient multiparty computation protocol for arithmetic circuits, UC-secure against a dishonest majority. The protocol consists of a preprocessing phase and an online phase. Neither the inputs nor the function to be computed have to be known during preprocessing. Moreover, the online phase is extremely efficient as it requires no cryptographic operations: the parties only need to exchange additive shares and verify information theoretic MACs. Our contribution is therefore twofold: from a theoretical point of view, we can base multiparty computation on a variety of different assumptions, while on the practical side we offer a protocol with better efficiency than any previous solution.","Title: On The Orthogonal Vector Problem And The Feasibility Of Unconditionally Secure Leakage-Resilient Computation\nYear: 2014\n\nAbstract: We consider unconditionally secure leakage resilient two-party computation. Security means that the leakage obtained by an adversary can be simulated using a similar amount of leakage from the private inputs or outputs. A related problem is known as circuit compilation, where there is only one device doing a computation on public input and output. Here the goal is to ensure that the adversary learns only the input/output behaviour of the computation, even given leakage from the internal state of the device. We study these problems in an enhanced version of the \"only computation leaks\" model, where the adversary is additionally allowed a bounded amount of global leakage from the state of the entity under attack. In this model, we show the first unconditionally secure leakage resilient two-party computation protocol. The protocol assumes access to correlated randomness in the form of a functionality f(ORT) that outputs pairs of orthogonal vectors (u, v) over some finite field, where the adversary can leak independently from u and from v. We also construct a general circuit compiler secure in the same leakage model. Our constructions work, even if the adversary is allowed to corrupt a constant fraction of the calls to f(ORT) and decide which vectors should be output. On the negative side, we show that unconditionally secure two-party computation and circuit compilation are in general impossible in the plain version of our model. It follows that even a somewhat unreliable version of f(ORT) cannot be implemented with unconditional security in the plain leakage model, using classical communication. However, we show that an implementation using quantum communication does exist. In particular, we propose a simple \"prepare-and-measure\" type protocol which we show secure using a new result on sampling from a quantum population. Although the protocol may produce a small number of incorrect pairs, this is sufficient for leakage resilient computation by our other results. To the best of our knowledge, this is the first time a quantum protocol is used constructively for leakage resilience.Note that the full version of this paper is available at [6].","Title: A quantum cipher with near optimal key-recycling\nYear: 2005\n\nAbstract: Assuming an insecure quantum channel and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.","Title: Constant-Overhead secure computation of boolean circuits using preprocessing\nYear: 2013\n\nAbstract: We present a protocol for securely computing a Boolean circuit C in presence of a dishonest and malicious majority. The protocol is unconditionally secure, assuming a preprocessing functionality that is not given the inputs. For a large number of players the work for each player is the same as computing the circuit in the clear, up to a constant factor. Our protocol is the first to obtain these properties for Boolean circuits. On the technical side, we develop new homomorphic authentication schemes based on asymptotically good codes with an additional multiplication property. We also show a new algorithm for verifying the product of Boolean matrices in quadratic time with exponentially small error probability, where previous methods only achieved constant error.","Title: Concurrent Zero-Knowledge is Easy in Practice.\nYear: 1999\n\nAbstract: We show that if any one-way function exists, then 3-round concurrent zero-knowledge arguments for all NP problems can be built in a model where a short auxiliary string with a prescribed distribution is available to the players. We also show that all known efficient identification schemes using specialized assumptions can be modified to work in this model with no essential loss of efficiency. We argue that the assumptions of the model will be satisfied in most practical scenarios where public...","Title: DAKOTA: hashing from a combination of modular arithmetic and symmetric cryptography\nYear: 2008\n\nAbstract: In this paper a cryptographic hash function is proposed, where collision resistance is based upon an assumption that involves squaring modulo an RSA modulus in combination with a one-way function that does not compress its input, and may therefore be constructed from standard techniques and assumptions. We are not able to reduce collision finding to factoring, but on the other hand, our hash function is more efficient than any known construction that makes use of modular squaring.","Title: General secure multi-party computation from any linear secret-sharing scheme\nYear: 2000\n\nAbstract: We show that verifiable secret sharing (VSS) and secure multi-party computation (MPC) among a set of n players can efficiently be based on any linear secret sharing scheme (LSSS) for the players, provided that the access structure of the LSSS allows MPC or VSS at all. Because an LSSS neither guarantees reconstructability when some shares are false, nor verifiability of a shared value, nor allows for the multiplication of shared values, an LSSS is an apparently much weaker primitive than VSS or MPC. Our approach to secure MPC is generic and applies to both the information-theoretic and the cryptographic setting. The construction is based on 1) a formalization of the special multiplicative property of an LSSS that is needed to perform a multiplication on shared values, 2) an efficient generic construction to obtain from any LSSS a multiplicative LSSS for the same access structure, and 3) an efficient generic construction to build verifiability into every LSSS (always assuming that the adversary structure allows for MPC or VSS at all). The protocols are efficient. In contrast to all previous information-theoretically secure protocols, the field size is not restricted (e.g, to be greater than n). Moreover, we exhibit adversary structures for which our protocols are polynomial in n while all previous approaches to MPC for non-threshold adversaries provably have super-polynomial complexity.","Title: Zero-Knowledge Proofs for Finite Field Arithmetic; or: Can Zero-Knowledge be for Free?\nYear: 1998\n\nAbstract: We present zero-knowledge proofs and arguments for arithmetic circuits over finiteprime fields, namely given a circuit, show in zero-knowledge that inputs can beselected leading to a given output. For a field GF (q), where q is an n-bit prime, acircuit of size O(n), and error probability 2, our protocols require communication ofO(n) bits. This is the same worst-cast complexity as the trivial (non zero-knowledge)interactive proof where the prover just reveals the input values....","Title: Linear Zero-Knowledge - A note on Efficient Zero-Knowledge Proofs and Arguments.\nYear: 1996\n\nAbstract: We present a 4-move zero-knowledge proof system[21] for any NP language L, which allows showing thatx 2 L with error probability less than 2\\Gammakusing communicationcorresponding to O(jxjc)+O(k) bit commitments,where c is a constant depending only on L. Wealso present a 4-move perfect zero knowledge interactiveargument for any NP-language L. On input x 2 L,the communication complexity is O(jxjc) \\Delta max(k; l) bits,where l is the security parameter for the prover1....","Title: Atomic Secure Multi-party Multiplication with Low Communication\nYear: 2007\n\nAbstract: We consider the standard secure multi-party multiplication protocol due to M. Rabin. This protocol is based on Shamir's secret sharing scheme and it can be viewed as a practical variation on one of the central techniques in the foundational results of Ben-Or, Goldwasser, and Wigderson and Chaum, Crépeau, and Damgaard on secure multi-party computation. Rabin's idea is a key ingredient to virtually all practical protocols in threshold cryptography.Given a passive t-adversary in the secure channels model with synchronous communication, for example, secure multiplication of two secret-shared elements from a finite field Kbased on this idea uses one communication round and has the network exchange O(n2) field elements, if t= 驴(n) and tn/2 and if nis the number of players. This is because each of O(n) players must perform Shamir secret sharing as part of the protocol. This paper demonstrates that under a few restrictions much more efficient protocols are possible; even at the level of a single multiplication.We demonstrate a twist on Rabin's idea that enables one-round secure multiplication with just O(n)bandwidthin certain settings, thus reducing it from quadratic to linear. The ideas involved can additionally be employed in the evaluation of arithmetic circuits, where under appropriate circumstances similar efficiency gains can be obtained.","Title: A generalization of Paillier’s public-key system with applications to electronic voting\nYear: 2010\n\nAbstract: We propose a generalization of Paillier’s probabilistic public-key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without losing the homomorphic property. We show that the generalization is as secure as Paillier’s original system and propose several ways to optimize implementations of both the generalized and the original scheme. We construct a threshold variant of the generalized scheme as well as zero-knowledge protocols to show that a given ciphertext encrypts one of a set of given plaintexts, and protocols to verify multiplicative relations on plaintexts. We then show how these building blocks can be used for applying the scheme to efficient electronic voting. This reduces dramatically the work needed to compute the final result of an election, compared to the previously best known schemes. We show how the basic scheme for a yes/no vote can be easily adapted to casting a vote for up to t out of L candidates. The same basic building blocks can also be adapted to provide receipt-free elections, under appropriate physical assumptions. The scheme for 1 out of L elections can be optimized such that for a certain range of the other parameter values, the ballot size is logarithmic in L.","Title: Secure computation, i/o-efficient algorithms and distributed signatures\nYear: 2012\n\nAbstract: We consider a setting where a set of n players use a set of m servers to store a large, private data set. Later the players decide on functions they want to compute on the data without the servers needing to know which computation is done, while the computation should be secure against a malicious adversary corrupting a constant fraction of the players and servers. Using packed secret sharing, the data can be stored in a compact way but will only be accessible in a block-wise fashion. We explore the possibility of using I/O-efficient algorithms to nevertheless compute on the data as efficiently as if random access was possible. We show that for sorting, priority queues and data mining, this can indeed be done. We show actively secure protocols of complexity within a constant factor of the passively secure solution. As a technical contribution towards this goal, we develop techniques for generating values of form r, gr for random secret-shared r∈ℤq and gr in a group of order q. This costs a constant number of exponentiation per player per value generated, even if less than n/3 players are malicious. This can be used for efficient distributed computing of Schnorr signatures. We further develop the technique so we can sign secret data in a distributed fashion at essentially the same cost.","Title: Towards Practical Public Key Systems Secure Against Chosen Ciphertext Attacks\nYear: 1991\n\nAbstract: We present two efficient constructions aimed at making public key systems secure against chosen ciphertext attacks. The first one applies to any deterministic public key system and modifies it into a system that is provably as hard to break under a passive attack as the original one, but has the potential of making a chosen ciphertext attack useless to an enemy. The second construction applies to the El Gamal/Diffie-Hellman public key system. Again, the modified system is provably as hard to break under a passive attack as the original one, and under an additional cryptographic assumption, a chosen ciphertext attack is provably useless to an enemy. We also point out a connection between such public-key systems and efficient identification schemes.","Title: Improving the Security of Quantum Protocols via Commit-and-Open\nYear: 2009\n\nAbstract: We consider two-party quantum protocols starting with a transmission of some random BB84 qubits followed by classical messages. We show a general \"compiler\" improving the security of such protocols: if the original protocol is secure against an \"almost honest\" adversary, then the compiled protocol is secure against an arbitrary computationally bounded (quantum) adversary. The compilation preserves the number of qubits sent and the number of rounds up to a constant factor. The compiler also preserves security in the bounded-quantum-storage model (BQSM), so if the original protocol was BQSM-secure, the compiled protocol can only be broken by an adversary who has large quantum memory and large computing power. This is in contrast to known BQSM-secure protocols, where security breaks down completely if the adversary has larger quantum memory than expected. We show how our technique can be applied to quantum identification and oblivious transfer protocols.","Title: Zero-Knowledge Proofs and String Commitments Withstanding Quantum Attacks\nYear: 2004\n\nAbstract: The concept of zero-knowledge (ZK) has become of fundamental importance in cryptography. However, in a setting where entities are modeled by quantum computers, classical arguments for proving ZK fail to hold since, in the quantum setting, the concept of rewinding is not generally applicable. Moreover, known classical techniques that avoid rewinding have various shortcomings in the quantum setting. We propose new techniques for building quantum zero-knowledge (QZK) protocols, which remain secure even under (active) quantum attacks. We obtain computational QZK proofs and perfect QZK arguments for any NP language in the common reference string model. This is based on a general method converting an important class of classical honest-verifier ZK (HVZK) proofs into QZK proofs. This leads to quite practical protocols if the underlying HVZK proof is efficient. These are the first proof protocols enjoying these properties, in particular the first to achieve perfect QZK. As part of our construction, we propose a general framework for building unconditionally hiding (trapdoor) string commitment schemes, secure against quantum attacks, as well as concrete instantiations based on specific (believed to be) hard problems. This is of independent interest, as these are the first unconditionally hiding string commitment schemes withstanding quantum attacks. Finally, we give a partial answer to the question whether QZK is possible in the plain model. We propose a new notion of QZK, non-oblivious verifier QZK, which is strictly stronger than honest-verifier QZK but weaker than full QZK, and we show that this notion can be achieved by means of efficient (quantum) protocols.","Title: How to re-use a one-time pad safely and almost optimally even if P = NP\nYear: 2014\n\nAbstract: uming an insecure quantum channel, a quantum computer, and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.","Title: The Chaining Lemma And Its Application\nYear: 2014\n\nAbstract: We present a new information-theoretic result which we call the Chaining Lemma. It considers a so-called \"chain\" of random variables, defined by a source distribution X-(0) with high min-entropy and a number (say, t in total) of arbitrary functions (T-1,...,T-t) which are applied in succession to that source to generate the chain X-(0) (sic) X-(1) (sic) X-(2)...(sic) X-(t). Intuitively, the Chaining Lemma guarantees that, if the chain is not too long, then either (i) the entire chain is \"highly random\", in that every variable has high min-entropy; or (ii) it is possible to find a point j (1 <= j <= t) in the chain such that, conditioned on the end of the chain i.e. X-(j) (sic) X(j+1)...(sic) X-(t), the preceding part X-(0) (sic) X-(1)...(sic) X-(j) remains highly random. We think this is an interesting information-theoretic result which is intuitive but nevertheless requires rigorous case-analysis to prove.We believe that the above lemma will find applications in cryptography. We give an example of this, namely we show an application of the lemma to protect essentially any cryptographic scheme against memorytampering attacks. We allow several tampering requests, the tampering functions can be arbitrary, however, they must be chosen from a bounded size set of functions that is fixed a priori.","Title: Compact VSS and Efficient Homomorphic UC Commitments.\nYear: 2014\n\nAbstract: We present a new compact verifiable secret sharing scheme, based on this we present the first construction of a homomorphic UC commitment scheme that requires only cheap symmetric cryptography, except for a small number of seed OTs. To commit to a k-bit string, the amortized communication cost is O(k) bits. Assuming a sufficiently efficient pseudorandom generator, the computational complexity is O(k) for the verifier and O(k(1+is an element of)) for the committer (where is an element of < 1 is a constant). In an alternative variant of the construction, all complexities are O(k . polylog(k)). Our commitment scheme extends to vectors over any finite field and is additively homomorphic. By sending one extra message, the prover can allow the verifier to also check multiplicative relations on committed strings, as well as verifying that committed vectors a, b satisfy a = phi(b) for a linear function phi. These properties allow us to non-interactively implement any one-sided functionality where only one party has input (this includes UC secure zero-knowledge proofs of knowledge). We also present a perfectly secure implementation of any multiparty functionality, based directly on our VSS. The communication required is proportional to a circuit implementing the functionality, up to a logarithmic factor. For a large natural class of circuits the overhead is even constant. We also improve earlier results by Ranellucci et al. on the amount of correlated randomness required for string commitments with individual opening of bits.","Title: Adaptive Versus Static Security In The Uc Model\nYear: 2014\n\nAbstract: We show that for certain class of unconditionally secure protocols and target functionalities, static security implies adaptive security in the UC model. Similar results were previously only known for models with weaker security and/or composition guarantees. The result is, for instance, applicable to a wide range of protocols based on secret sharing. It \"explains\" why an often used proof technique for such protocols works, namely where the simulator runs in its head a copy of the honest players using dummy inputs and generates a protocol execution by letting the dummy players interact with the adversary. When a new player P-i is corrupted, the simulator adjusts the state of its dummy copy of P-i to be consistent with the real inputs and outputs of P-i and gives the state to the adversary. Our result gives a characterization of the cases where this idea will work to prove adaptive security. As a special case, we use our framework to give the first proof of adaptive security of the seminal BGW protocol in the UC framework.","Title: On the Communication required for Unconditionally Secure Multiplication.\nYear: 2016\n\nAbstract: Many information-theoretic secure protocols are known for general secure multi-party computation, in the honest majority setting, and in the dishonest majority setting with preprocessing. All known protocols that are efficient in the circuit size of the evaluated function follow the same \\\"gate-by-gate\\\" design pattern: we work through an arithmetic boolean circuit on secret-shared inputs, such that after we process a gate, the output of the gate is represented as a random secret sharing among the players. This approach usually allows non-interactive processing of addition gates but requires communication for every multiplication gate. Thus, while information-theoretic secure protocols are very efficient in terms of computational work, they seem to require more communication and more rounds than computationally secure protocols. Whether this is inherent is an open and probably very hard problem. However, in this work we show that it is indeed inherent for protocols that follow the \\\"gate-by-gate\\\" design pattern. We present the following results:In the honest majority setting, as well as for dishonest majority with preprocessing, any gate-by-gate protocol must communicate $$\\\\varOmega n$$ bits for every multiplication gate, where n is the number of players.In the honest majority setting, we show that one cannot obtain a bound that also grows with the field size. Moreover, for a constant number of players, amortizing over several multiplication gates does not allow us to save on the computational work, and --- in a restricted setting --- we show that this also holds for communication. All our lower bounds are met up﾿to a constant factor by known protocols that follow the typical gate-by-gate paradigm. Our results imply that a fundamentally new approach must be found in order to improve the communication complexity of known protocols, such as BGW, GMW, SPDZ etc.","Title: Rate-1, Linear Time and Additively Homomorphic UC Commitments.\nYear: 2016\n\nAbstract: We construct the first UC commitment scheme for binary strings with the optimal properties of rate approaching 1 and linear time complexity in the amortised sense, using a small number of seed OTs. On top of this, the scheme is additively homomorphic, which allows for applications to maliciously secure 2-party computation. As tools for obtaining this, we make three contributions of independent interest: we construct the first binary linear time encodable codes with non-trivial distance and rate approaching 1, we construct the first almost universal hash function with small seed that can be computed in linear time, and we introduce a new primitive called interactive proximity testing that can be used to verify whether a string is close to a given linear code.","Title: Access Control Encryption: Enforcing Information Flow with Cryptography.\nYear: 2016\n\nAbstract: We initiate the study of Access Control Encryption ACE, a novel cryptographic primitive that allows fine-grained access control, by giving different rights to different users not only in terms of which messages they are allowed to receive, but also which messages they are allowed to send. Classical examples of security policies for information flow are the well known Bell-Lapadula﾿[BL73] or Biba﾿[Bib75] model: in a nutshell, the Bell-Lapadula model assigns roles to every user in the system e.g., public, secret and top-secret. A users' role specifies which messages the user is allowed to receive i.e., the no read-up rule, meaning that users with public clearance should not be able to read messages marked as secret or top-secret but also which messages the user is allowed to send i.e., the no write-down rule, meaning that a malicious user with top-secret clearance should not be able to write messages marked as secret or public. To the best of our knowledge, no existing cryptographic primitive allows for even this simple form of access control, since no existing cryptographic primitive enforces any restriction on what kind of messages one should be able to encrypt. Our contributions are:Introducing and formally defining access control encryption ACE;A construction of ACE with complexity linear in the number of the roles based on classic number theoretic assumptions DDH, Paillier;A construction of ACE with complexity polylogarithmic in the number of roles based on recent results on cryptographic obfuscation;","Title: Confidential Benchmarking based on Multiparty Computation.\nYear: 2016\n\nAbstract: We report on the design and implementation of a system that uses multiparty computation to enable banks to benchmark their customers' confidential performance data against a large representative set of confidential performance data from a consultancy house. The system ensures that both the banks' and the consultancy house's data stays confidential, the banks as clients learn nothing but the computed benchmarking score. In the concrete business application, the developed prototype helps Danish banks to find the most efficient customers among a large and challenging group of agricultural customers with too much debt. We propose a model based on linear programming for doing the benchmarking and implement it using the SPDZ protocol by Damgard et al., which we modify using a new idea that allows clients to supply data and get output without having to participate in the preprocessing phase and without keeping state during the computation. We ran the system with two servers doing the secure computation using a database with information on about 2500 users. Answers arrived in about 25 s.","Title: Fast Oblivious AES\\\\A dedicated application of the MiniMac protocol.\nYear: 2015\n\nAbstract: We present actively secure multi-party computation of the Advanced Encryption Standard AES. To the best of our knowledge it is the fastest of its kind to date. We start from an efficient actively secure evaluation of general binary circuits that was implemented by the authors of [DLT14]. They presented an optimized implementation of the so-called MiniMac protocol [DZ13] that runs in the pre-processing model, and applied this to a binary AES circuit. In this paper we describe how to dedicate the pre-processing to the structure of AES, which improves significantly the throughput and latency of previous actively secure implementations. We get a latency of about 6 ms and amortised time about 0.4 ms per AES block, which seems completely adequate for practical applications such as verification of 1-time passwords.","Title: Better Preprocessing for Secure Multiparty Computation.\nYear: 2016\n\nAbstract: We present techniques and protocols for the preprocessing of secure multiparty computation (MPC), focusing on the so-called SPDZ MPC scheme [14] and its derivatives [1,11,13]. These MPC schemes consist of a so-called preprocessing or offline phase where correlated randomness is generated that is independent of the inputs and the evaluated function, and an online phase where such correlated randomness is consumed to securely and efficiently evaluate circuits. In the recent years, it has been shown that such protocols (such as [5,17,18]) turn out to be very efficient in practice. While much research has been conducted towards optimizing the online phase of the MPC protocols, there seems to have been less focus on the offline phase of such protocols (except for [11]). With this work, we want to close this gap and give a toolbox of techniques that aim at optimizing the preprocessing. We support both instantiations over small fields and large rings using somewhat homomorphic encryption and the Paillier cryptosystem [19], respectively. In the case of small fields, we show how the preprocessing overhead can basically be made independent of the field characteristic. In the case of large rings, we present a protocol based on the Paillier cryptosystem which has a lower message complexity than previous protocols and employs more efficient zero-knowledge proofs that, to the best of our knowledge, were not presented in previous work.","Title: Unconditionally Secure Computation with Reduced Interaction.\nYear: 2015\n\nAbstract: We study the question of how much interaction is needed for unconditionally secure multiparty computation. We first consider the number of messages that need to be sent to compute a Boolean function with semi-honest security, where all n parties learn the result. We consider two classes of functions called t-difficult and t-very difficult functions, where t refers to the number of corrupted players. For instance, the AND of an input bit from each player is t-very difficult while the XOR is t-difficult but not t-very difficult. We show lower bounds on the message complexity of both types of functions, considering two notions of message complexity called conservative and liberal, where conservative is the more standard one. In all cases the bounds are $$\\\\varOmega nt$$ Ωnt. We also show almost matching upper bounds for $$t=1$$ t=1 and functions in a rich class $$PSM_\\\\mathsf{eff}$$ PSMeff including non-deterministic log-space, as well as a stronger upper bound for the XOR function. In particular, we find that the conservative message complexity of 1-very difficult functions in $$PSM_\\\\mathsf{eff}$$ PSMeff is 2n, while the conservative message complexity for XOR and $$t=1$$ t=1 is $$2n-1$$ 2n-1. Next, we consider round complexity. It is a long-standing open problem to determine whether all efficiently computable functions can also be efficiently computed in constant-round with unconditional security. Motivated by this, we consider the question of whether we can compute any function securely, while minimizing the interaction of some of the players? And if so, how many players can this apply to? Note that we still want the standard security guarantees correctness, privacy, termination and we consider the standard communication model with secure point-to-point channels. We answer the questions as follows: for passive security, with $$n=2t+1$$ n=2t+1 players and t corruptions, up﾿to t players can have minimal interaction, i.e., they send 1 message in the first round to each of the $$t+1$$ t+1 remaining players and receive one message from each of them in the last round. Using our result on message complexity, we show that this is unconditionally optimal. For malicious security with $$n=3t+1$$ n=3t+1 players and t corruptions, up﾿to t players can have minimal interaction, and we show that this is also optimal.","Title: Adaptively Secure Multi-Party Computation from LWE (via Equivocal FHE).\nYear: 2016\n\nAbstract: Adaptively secure Multi-Party Computation MPC is an essential and fundamental notion in cryptography. In this work, we construct Universally Composable UC MPC protocols that are adaptively secure against all-but-one corruptions based on LWE. Our protocols have a constant number of rounds and communication complexity dependant only on the length of the inputs and outputs it is independent of the circuit size. Such protocols were only known assuming an honest majority. Protocols in the dishonest majority setting, such as the work of Ishai et al. CRYPTO 2008, require communication complexity proportional to the circuit size. In addition, constant-round adaptively secure protocols assuming dishonest majority are known to be impossible in the stand-alone setting with black-box proofs of security in the plain model. Here, we solve the problem in the UC setting using a set-up assumption which was shown necessary in order to achieve dishonest majority. The problem of constructing adaptively secure constant-round MPC protocols against arbitrary corruptions is considered a notorious hard problem. A recent line of works based on indistinguishability obfuscation construct such protocols with near-optimal number of rounds against arbitrary corruptions. However, based on standard assumptions, adaptively secure protocols secure against even just all-but-one corruptions with near-optimal number of rounds are not known. However, in this work we provide a three-round solution based only on LWE and NIZK secure against all-but-one corruptions. In addition, Asharov et al. EUROCRYPT 2012 and more recently Mukherjee and Wichs ePrint 2015 presented constant-round protocols based on LWE which are secure only in the presence of static adversaries. Assuming NIZK and LWE their static protocols run in two rounds where the latter one is only based on a common random string. Assuming adaptively secure UC NIZK, proposed by Groth et al. ACM 2012, and LWE as mentioned above our adaptive protocols run in three rounds. Our protocols are constructed based on a special type of cryptosystem we call equivocal FHE from LWE. We also build adaptively secure UC commitments and UC zero-knowledge proofs of knowledge from LWE. Moreover, in the decryption phase using an AMD code mechanism we avoid the use of ZK and achieve communication complexity that does not scale with the decryption circuit.","Title: Entangled Encodings and Data Entanglement\nYear: 2015\n\nAbstract: We introduce a new cryptographic tool that we dub entangled encoding scheme. An entangled encoding allows a set of users to encode their files into a single digital \\\"clew\\\" such that the following two properties are satisfied. (1) Privacy: The resulting encoding reveals no information about the files contained inside the clew; (2) All-or-nothing integrity (AONI): It is impossible to modify or delete any significant part of the encoding without affecting all files contained in the clew. We provide a concrete instantiation of an entangled encoding scheme with unconditional security, based on polynomial interpolation over a finite field. Finally, we show an appealing application of entangled encodings to the setting of secure cloud storage, where a set of users store their files at a potentially malicious cloud provider and want to ensure that their data remain safe and unblemished.","Title: How to prove knowledge of small secrets.\nYear: 2016\n\nAbstract: We propose a new zero-knowledge protocol applicable to additively homomorphic functions that map integer vectors to an Abelian group. The protocol demonstrates knowledge of a short preimage and achieves amortised efficiency comparable to the approach of Cramer and Damgård from Crypto 2010, but gives a much tighter bound on what we can extract from a dishonest prover. Towards achieving this result, we develop an analysis for bins-and-balls games that might be of independent interest. We also provide a general analysis of rewinding of a cut-and-choose protocol as well as a method to use Lyubachevsky's rejection sampling technique efficiently in an interactive protocol when many proofs are given simultaneously. Our new protocol yields improved proofs of plaintext knowledge for Ring-LWE-based cryptosystems, where such general techniques were not known before. Moreover, they can be extended to prove preimages of homomorphic hash functions as well.","Title: Amortized Complexity of Zero-Knowledge Proofs Revisited: Achieving Linear Soundness Slack.\nYear: 2017\n\nAbstract: We propose a new zero-knowledge protocol for proving knowledge of short preimages under additively homomorphic functions that map integer vectors to an Abelian group. The protocol achieves amortized efficiency in that it only needs to send O(n) function values to prove knowledge of n preimages. Furthermore we significantly improve previous bounds on how short a secret we can extract from a dishonest prover, namely our bound is a factor O(k) larger than the size of secret used by the honest prover, where k is the statistical security parameter. In the best previous result, the factor was O(k(log k) n). Our protocol can be applied to give proofs of knowledge for plaintexts in (Ring-) LWE-based cryptosystems, knowledge of preimages of homomorphic hash functions as well as knowledge of committed values in some integer commitment schemes.","Title: Resource-efficient OT combiners with active security.\nYear: 2017\n\nAbstract: An OT-combiner takes n candidate implementations of the oblivious transfer (OT) functionality, some of which may be faulty, and produces a secure instance of oblivious transfer as long as a large enough number of the candidates are secure. We see an OT-combiner as a 2-party protocol that can make several black-box calls to each of the n OT candidates, and we want to protect against an adversary that can corrupt one of the parties and a certain number of the OT candidates, obtaining their inputs and (in the active case) full control of their outputs.","Title: Secure Arithmetic Computation with Constant Computational Overhead.\nYear: 2017\n\nAbstract: We study the complexity of securely evaluating an arithmetic circuit over a finite field F in the setting of secure two-party computation with semi-honest adversaries. In all existing protocols, the number of arithmetic operations per multiplication gate grows either linearly with log vertical bar F vertical bar or polylogarithmically with the security parameter. We present the first protocol that only makes a constant (amortized) number of field operations per gate. The protocol uses the underlying field F as a black box, and its security is based on arithmetic analogues of well-studied cryptographic assumptions. Our protocol is particularly appealing in the special case of securely evaluating a \"vector-OLE\" function of the form ax + b, where x is an element of F is the input of one party and a, b is an element of F-w are the inputs of the other party. In this case, which is motivated by natural applications, our protocol can achieve an asymptotic rate of 1/3 (i.e., the communication is dominated by sending roughly 3w elements of F). Our implementation of this protocol suggests that it outperforms competing approaches even for relatively small fields F and over fast networks. Our technical approach employs two new ingredients that may be of independent interest. First, we present a general way to combine any linear code that has a fast encoder and a cryptographic (\"LPN-style\") pseudorandomness property with another linear code that supports fast encoding and erasure-decoding, obtaining a code that inherits both the pseudorandomness feature of the former code and the efficiency features of the latter code. Second, we employ local arithmetic pseudo-random generators, proposing arithmetic generalizations of boolean candidates that resist all known attacks.","Title: The TinyTable Protocol for 2-Party Secure Computation, or: Gate-Scrambling Revisited.\nYear: 2017\n\nAbstract: We propose a new protocol, nicknamed TinyTable, for maliciously secure 2-party computation in the preprocessing model. One version of the protocol is useful in practice and allows, for instance, secure AES encryption with latency about 1ms and amortized time about 0.5 mu s per AES block on a fast cloud set-up. Another version is interesting from a theoretical point of view: we achieve a maliciously and unconditionally secure 2-party protocol in the preprocessing model for computing a Boolean circuit, where both the communication complexity and preprocessed data size needed is O(s) where s is the circuit size, while the computational complexity is O(k(epsilon)s) where k is the statistical security parameter and epsilon < 1 is a constant. For general circuits with no assumption on their structure, this is the best asymptotic performance achieved so far in this model.","Title: Yet Another Compiler for Active Security or: Efficient MPC Over Arbitrary Rings.\nYear: 2018\n\nAbstract: We present a very simple yet very powerful idea for turning any passively secure MPC protocol into an actively secure one, at the price of reducing the threshold of tolerated corruptions. Our compiler leads to a very efficient MPC protocols for the important case of secure evaluation of arithmetic circuits over arbitrary rings e.g., the natural case of Z(2l)) for a small number of parties. We show this by giving a concrete protocol in the preprocessing model for the popular setting with three parties and one corruption. This is the first protocol for secure computation over rings that achieves active security with constant overhead.","Title: Continuous Nmc Secure Against Permutations And Overwrites, With Applications To Cca Secure Commitments\nYear: 2018\n\nAbstract: Non-Malleable Codes (NMC) were introduced by Dziembowski, Pietrzak and Wichs in ICS 2010 as a relaxation of error correcting codes and error detecting codes. Faust, Mukherjee, Nielsen, and Venturi in TCC 2014 introduced an even stronger notion of non-malleable codes called continuous non-malleable codes where security is achieved against continuous tampering of a single codeword without re-encoding.We construct information theoretically secure CNMC resilient to bit permutations and overwrites, this is the first Continuous NMC constructed outside of the split-state model.In this work we also study relations between the CNMC and parallel CCA commitments. We show that the CNMC can be used to bootstrap a Self-destruct parallel CCA bit commitment to a Self-destruct parallel CCA string commitment, where Self-destruct parallel CCA is a weak form of parallel CCA security. Then we can get rid of the Self-destruct limitation obtaining a parallel CCA commitment, requiring only one-way functions.","Title: SPD \\mathbb Z_2^k : Efficient MPC mod 2^k for Dishonest Majority.\nYear: 2018\n\nAbstract: Most multi-party computation protocols allow secure computation of arithmetic circuits over a finite field, such as the integers modulo a prime. In the more natural setting of integer computations modulo (2^{k}), which are useful for simplifying implementations and applications, no solutions with active security are known unless the majority of the participants are honest.","Title: More Efficient Commitments from Structured Lattice Assumptions.\nYear: 2018\n\nAbstract: We present a practical construction of an additively homomorphic commitment scheme based on structured lattice assumptions, together with a zero-knowledge proof of opening knowledge. Our scheme is a design improvement over the previous work of Benhamouda et al. in that it is not restricted to being statistically binding. While it is possible to instantiate our scheme to be statistically binding or statistically hiding, it is most efficient when both hiding and binding properties are only computational. This results in approximately a factor of 4 reduction in the size of the proof and a factor of 6 reduction in the size of the commitment over the aforementioned scheme.","Title: Proofs of Replicated Storage Without Timing Assumptions\nYear: 2018\n\nAbstract: In this paper we provide a formal treatment of proof of replicated storage, a novel cryptographic primitive recently proposed in the context of a novel cryptocurrency, namely Filecoin. In a nutshell, proofs of replicated storage is a solution to the following problem: A user stores a file m on n different servers to ensure that the file will be available even if some of the servers fail. Using proof of retrievability, the user could check that every server is indeed storing the file. However, what if the servers collude and, in order to save on resources, decide to only store one copy of the file? A proof of replicated storage guarantees that, unless the (potentially colluding) servers are indeed reserving the space necessary to store n copies of the file, the user will not accept the proofs. While some candidate proofs of replicated storage have already been proposed, their soundness relies on timing assumptions i.e., the user must reject the proof if the prover does not reply within a certain time-bound. In this paper we provide the first construction of a proof of replication which does not rely on any timing assumptions.","Title: A \"proof-reading\" of some issues in cryptography\nYear: 2007\n\nAbstract: In this paper, we identify some issues in the interplay between practice and theory in cryptography, issues that have repeatedly appeared in different incarnations over the years. These issues are related to fundamental concepts in the field, e.g., to what extent we can prove that a system is secure and what theoretic results on security mean for practical applications. We argue that several such issues are often overlooked or misunderstood, and that it may be very productive if both theoreticians and practitioners think more consciously about these issues and act accordingly.","Title: Isolated proofs of knowledge and isolated zero knowledge\nYear: 2008\n\nAbstract: We consider proof of knowledge protocols where the cheating prover may communicate with some external adversarial environment during the run of the proof. Without additional setup assumptions, no witness hiding protocol can securely ensure that the prover knows a witness in this scenario. This is because the prover may just be forwarding messages between the environment and the verifier while the environment performs all the necessary computation. In this paper we consider an l-isolated prover, which is restricted to exchanging at most l bits of information with its environment. We introduce a new notion called l-isolated proofs of knowledge (l-IPoK). These protocols securely ensure that an l-isolated prover knows the witness. To prevent the above-mentioned attack, an l-IPoK protocol has to have communication complexity greater than l. We show that for any relation in NP and any value l, there is an l-IPoK protocol for that relation. In addition, the communication complexity of such a protocol only needs to be larger than l by a constant multiplicative factor.","Title: Practical Threshold RSA Signatures without a Trusted Dealer\nYear: 2001\n\nAbstract: We propose a threshold RSA scheme which is as efficient as the fastest previous threshold RSA scheme (by Shoup), but where two assumptions needed in Shoup's and in previous schemes can be dropped, namely that the modulus must be a product of safe primes and that a trusted dealer generates the keys. The robustness (but not the unforgeability) of our scheme depends on a new intractability assumption, in addition to security of the underlying standard RSA scheme.","Title: Perfectly secure oblivious RAM without random oracles\nYear: 2011\n\nAbstract: We present an algorithm for implementing a secure oblivious RAM where the access pattern is perfectly hidden in the information theoretic sense, without assuming that the CPU has access to a random oracle. In addition we prove a lower bound on the amount of randomness needed for implementing an information theoretically secure oblivious RAM.","Title: Unconditionally Secure and Universally Composable Commitments from Physical Assumptions.\nYear: 2013\n\nAbstract: We present a constant-round unconditional black-box compiler that transforms any ideal (i.e., statistically-hiding and statisticallybinding) straight-line extractable commitment scheme, into an extractable and equivocal commitment scheme, therefore yielding to UC-security [9]. We exemplify the usefulness of our compiler by providing two (constant-round) instantiations of ideal straight-line extractable commitment based on (malicious) PUFs [36] and stateless tamper-proof hardware tokens [26], therefore achieving the first unconditionally UC-secure commitment with malicious PUFs and stateless tokens, respectively. Our constructions are secure for adversaries creating arbitrarily malicious stateful PUFs/tokens. Previous results with malicious PUFs used either computational assumptions to achieve UC-secure commitments or were unconditionally secure but only in the indistinguishability sense [36]. Similarly, with stateless tokens, UC-secure commitments are known only under computational assumptions [13,24,15], while the (not UC) unconditional commitment scheme of [23] is secure only in a weaker model in which the adversary is not allowed to create stateful tokens. Besides allowing us to prove feasibility of unconditional UC-security with (malicious) PUFs and stateless tokens, our compiler can be instantiated with any ideal straight-line extractable commitment scheme, thus allowing the use of various setup assumptions which may better fit the application or the technology available.","Title: Lectures on Data Security, Modern Cryptology in Theory and Practice, Summer School, Aarhus, Denmark, July 1998\nYear: 1999\n\nAbstract: From the Publisher: This tutorial volume is based on a summer school on cryptology and data security held in Aarhus, Denmark, in July 1998. The ten revised lectures presented are devoted to core topics in modern cryptology. In accordance with the educational objectives of the school, elementary introductions are provided to central topics, various examples are given of the problems encountered, and this is supplemented with solutions, open problems, and reference to further reading. The resulting book is ideally suited as an up-to-date introductory text for students and IT professionals interested in modern cryptology.","Title: Oblivious Transfer from Any Non-Trivial Elastic Noisy Channels via Secret Key Agreement.\nYear: 2016\n\nAbstract: A $$\\\\gamma ,\\\\delta $$ γ,﾿-elastic channel is a binary symmetric channel between a sender and a receiver where the error rate of an honest receiver is $$\\\\delta $$ ﾿ while the error rate of a dishonest receiver lies within the interval $$[\\\\gamma , \\\\delta ]$$ [γ,﾿]. In this paper, we show that from any non-trivial elastic channel i.e., $$0<\\\\gamma<\\\\delta <\\\\frac{1}{2}$$ 0<γ<﾿<12 we can implement oblivious transfer with information-theoretic security. This was previously Khurana et al., Eurocrypt 2016 only known for a subset of these parameters. Our technique relies on a new way to exploit protocols for information-theoretic key agreement from noisy channels. We also show that information-theoretically secure commitments where the receiver commits follow from any non-trivial elastic channel.","Title: Generic Lower Bounds for Root Extraction and Signature Schemes in General Groups\nYear: 2002\n\nAbstract: We study the problem of root extraction in finite Abelian groups, where the group order is unknown. This is a natural generalization of the problem of decrypting RSA ciphertexts. We study the complexity of this problem for generic algorithms, that is, algorithms that work for any group and do not use any special properties of the group at hand. We prove an exponential lower bound on the generic complexity of root extraction, even if the algorithm can choose the \"public exponent\" itself. In other words, both the standard and the strong RSA assumption are provably true w.r.t. generic algorithms. The results hold for arbitrary groups, so security w.r.t. generic attacks follows for any cryptographic construction based on root extracting. As an example of this, we revisit Cramer-Shoup signature scheme [10]. We modify the scheme such that it becomes a generic algorithm. This allows us to implement it in RSA groups without the original restriction that the modulus must be a product of safe primes. It can also be implemented in class groups. In all cases, security follows from a well defined complexity assumption (the strong root assumption), without relying on random oracles, and the assumption is shown to be true w.r.t. generic attacks.","Title: On the Key-Uncertainty of Quantum Ciphers and the Computational Security of One-way Quantum Transmission.\nYear: 2004\n\nAbstract: We consider the scenario where Alice wants to send a secret (classical) n-bit message to Bob using a classical key, and where only one-way transmission from Alice to Bob is possible. In this case, quantum communication cannot help to obtain perfect secrecy with key length smaller then n. We study the question of whether there might still be fundamental differences between the case where quantum as opposed to classical communication is used. In this direction, we show that there exist ciphers with perfect security producing quantum ciphertext where, even if an adversary knows the plaintext and applies an optimal measurement on the ciphertext, his Shannon uncertainty about the key used is almost maximal. This is in contrast to the classical case where the adversary always learns n bits of information on the key in a known plaintext attack. We also show that there is a limit to how different the classical and quantum cases can be: the most probable key, given matching plain- and ciphertexts, has the same probability in both the quantum and the classical cases. We suggest an application of our results in the case where only a short secret key is available and the message is much longer. Namely, one can use a pseudorandom generator to produce from the short key a stream of keys for a quantum cipher, using each of them to encrypt an n-bit block of the message. Our results suggest that an adversary with bounded resources in a known plaintext attack may potentially be in a much harder situation against quantum stream-ciphers than against any classical stream-cipher with the same parameters.","Title: Secure Signature Schemes based on Interactive Protocols.\nYear: 1995\n\nAbstract: Given only an interactive protocol of a certain type as a primitive, we can build a (non-interactive) signature scheme that is secure in the strongest sense of Goldwasser, Micali and Rivest (see [11]): not existentially forgeable under adaptively chosen message attacks. There are numerous examples of primitives that satisfy our conditions, e.g. Feige-Fiat-Shamir, Schnorr, Guillou-Quisquater, Okamoto and Brickell-Mc.Curley ([9], [17], [12], [15], [3]). A main consequence is that efficient and secure signature schemes can now also be based on computationally difficult problems other then factoring (see [11]), such as the discrete logarithm problem. In fact, the existence of one-way group homomorphisms is a sufficient assumption to support our construction. As we also demonstrate that our construction can be based on claw-free pairs of trapdoor permutations, our results can be viewed as a generalization of [11].","Title: Secure Multiparty Computation Goes Live\nYear: 2009\n\nAbstract: In this note, we report on the first large-scale and practical application of secure multiparty computation, which took place in January 2008. We also report on the novel cryptographic protocols that were used.","Title: Information-Theoretically Secure MPC Against Mixed Dynamic Adversaries\nYear: 2021\n\nAbstract: In this work we consider information-theoretically secure MPC against an mixed adversary who can corrupt t(p) parties passively, t(a) parties actively, and can make t(f) parties fail-stop. With perfect security, it is known that every function can be computed securely if and only if 3t(a)+2t(p)+t(f) < n, and for statistical security the bound is 2t(a)+2t(p)+ t(f) < n. These results say that for each given set of parameters (t(a), t(p), t(f)) respecting the inequality, there exists a protocol secure against this particular choice of corruption thresholds. In this work we consider a dynamic adversary. Here, the goal is a single protocol that is secure, no matter which set of corruption thresholds (t(a), t(p), t(f)) from a certain class is chosen by the adversary. A dynamic adversary can choose a corruption strategy after seeing the protocol and so is much stronger than a standard adversary. Dynamically secure protocols have been considered before for computational security. Also the information theoretic case has been studied, but only considering non-threshold general adversaries, leading to inefficient protocols. We consider threshold dynamic adversaries and information theoretic security. For statistical security we show that efficient dynamic secure function evaluation (SFE) is possible if and only if 2t(a) + 2t(p) + t(f) < n, but any dynamically secure protocol must use Omega(n) rounds, even if only fairness is required. Further, general reactive MPC is possible if we assume in addition that 2t(a) + 2t(f) <= n, but fair reactive MPC only requires 2t(a) + 2t(p) + t(f) < n. For perfect security we show that both dynamic SFE and verifiable secret sharing (VSS) are impossible if we only assume 3t(a) + 2t(p) + t(f) < n and remain impossible even if we also assume t(f) = 0. On the other hand, perfect dynamic SFE with guaranteed output delivery (G.O.D.) is possible when either t(p) = 0 or t(a) = 0 i.e. if instead we assume 3t(a) + t(f) < n or 2t(p) + t(f) < n. Further, perfect dynamic VSS with G.O.D. is possible under the additional conditions 3t(a) + 3/2t(f) <= n or 2t(p) + 2t(f) <= n. These conditions are also sufficient for dynamic perfect reactive MPC."],"string":"[\n \"Title: Convertible Undeniable Signatures\\nYear: 1990\\n\\nAbstract: We introduce a new concept called convertible undeniable signature schemes. In these schemes, release of a single bit string by the signer turns all of his signatures, which were originally undeniable\\n signatures, into ordinary digital signatures. We prove that the existence of such schemes is implied by the existence of digital\\n signature schemes. Then, looking at the problem more practically, we present a very efficient convertible undeniable signature\\n scheme. This scheme has the added benefit that signatures can also be selectively converted.\",\n \"Title: Entangled Cloud Storage.\\nYear: 2016\\n\\nAbstract: Entangled cloud storage (Aspnes et¿al., ESORICS 2004) enables a set of clients to \\\\\\\"entangle\\\\\\\" their files into a single clew to be stored by a (potentially malicious) cloud provider. The entanglement makes it impossible to modify or delete significant part of the clew without affecting all files encoded in the clew. A clew keeps the files in it private but still lets each client recover his own data by interacting with the cloud provider; no cooperation from other clients is needed. At the same time, the cloud provider is discouraged from altering or overwriting any significant part of the clew as this will imply that none of the clients can recover their files.We put forward the first simulation-based security definition for entangled cloud storage, in the framework of universal composability (Canetti, 2001). We then construct a protocol satisfying our security definition, relying on an entangled encoding scheme based on privacy-preserving polynomial interpolation; entangled encodings were originally proposed by Aspnes et¿al. as useful tools for the purpose of data entanglement. As a contribution of independent interest we revisit the security notions for entangled encodings, putting forward stronger definitions than previous work (that for instance did not consider collusion between clients and the cloud provider).Protocols for entangled cloud storage find application in the cloud setting, where clients store their files on a remote server and need to be ensured that the cloud provider will not modify or delete their data illegitimately. Current solutions, e.g.,¿based on Provable Data Possession and Proof of Retrievability, require the server to be challenged regularly to provide evidence that the clients' files are stored at a given time. Entangled cloud storage provides an alternative approach where any single client operates implicitly on behalf of all others, i.e.,¿as long as one client's files are intact, the entire remote database continues to be safe and unblemished. We model simulation-based security for data entanglement in the cloud.We introduce stronger security notions for entangled encoding schemes.We give a protocol for entangled storage satisfying our simulation-based definition.\",\n \"Title: Unclonable Group Identification\\nYear: 2005\\n\\nAbstract: We introduce and motivate the concept of unclonable group identification, that provides maximal protection against sharing of iden- tities while still protecting the anonymity of users. We prove that the notion can be realized from any one-way function and suggest a more ecient implementation based on specific assumptions.\",\n \"Title: On the (im)possibility of basing oblivious transfer and bit commitment on weakened security assumptions\\nYear: 1999\\n\\nAbstract: We consider the problem of basing Oblivious Transfer (OT) and Bit Commitment (BC), with information theoretic security, on seemingly weaker primitives.We introduce a general model for describing such primitives, called Weak Generic Transfer (WGT). This model includes as important special cases Weak Oblivious Transfer (WOT), where both the sender and receiver may learn too much about the other party's input, and a new, more realistic model of noisy channels, called unfair noisy channels. An unfair noisy channel has a known range of possible noise levels; protocols must work for any level within this range against adversaries who know the actual noise level. We give a precise characterization for when one can base OT on WOT. When the deviation of the WOT from the ideal is above a certain threshold, we show that no information-theoretic reductions from OT (even against passive adversaries) and BC exist; when the deviation is below this threshold, we give a reduction from OT (and hence BC) that is information-theoretically secure against active adversaries. For unfair noisy channels we show a similar threshold phenomenon for bit commitment. If the upper bound on the noise is above a threshold (given as a function of the lower bound) then no information-theoretic reduction from OT (even against passive adversaries) or BC exist; when it is below this threshold we give a reduction from BC. As a partial result, we give a reduction from OT to UNC for smaller noise intervals.\",\n \"Title: Honest Verifier vs Dishonest Verifier in Public Cain Zero-Knowledge Proofs\\nYear: 1995\\n\\nAbstract: This paper presents two transformations of public-coin/Arthur-Merlin proof systems which are zero-knowledge with respect to the honest verifier into (public-coin/Arthur-Merlin) proof systems which are zero-knowledge with respect to any verifier.The first transformation applies only to constant-round proof systems. It builds on Damg氓rd's transformation (see Crypto93), using ordinary hashing functions instead of the interactive hashing protocol (of Naor, Ostrovsky, Venkatesan and Yung - see Crypto92) which was used by Damg氓rd. Consequently, the protocols resulting from our transformation have much lower round-complexity than those derived by Damg氓rd's transformation. As in Damg氓rd's transformation, our transformation preserves statistical/perfect zero-knowledge and does not rely on any computational assumptions. However, unlike Damg氓rd's transformation, the new transformation is not applicable to argument systems or to proofs of knowledge.The second transformation can be applied to proof systems of arbitrary number of rounds, but it only preserves statistical zero-knowledge. It assumes the existence of secure commitment schemes and transforms any public-coin proof which is statistical zero-knowledge with respect to the honest into one which is statistical zero-knowledge (in general). It follows, by a result of Ostrovsky and Wigderson (1993), that any language which is \\\"hard on the average\\\" and has a public-coin proof system which is statistical zero-knowledge with respect to the honest verifier, has a proof system which is statistical zero-knowledge (with respect to any verifier).\",\n \"Title: Zero-Knowledge proofs with low amortized communication from lattice assumptions\\nYear: 2012\\n\\nAbstract: We construct zero-knowledge proofs of plaintext knowledge (PoPK) and correct multiplication (PoPC) for the Regev encryption scheme with low amortized communication complexity. Previous constructions of both PoPK and PoPC had communication cost linear in the size of the public key (roughly quadratic in the lattice dimension, ignoring logarithmic factors). Furthermore, previous constructions of PoPK suffered from one of the following weaknesses: either the message and randomness space were restricted, or there was a super-polynomial gap between the size of the message and randomness that an honest prover chose and the size of which an accepting verifier would be convinced. The latter weakness was also present in the existent PoPC protocols. In contrast, O(n) proofs (for lattice dimension n) in our PoPK and PoPC protocols have communication cost linear in the public key. Thus, we improve the amortized communication cost of each proof by a factor linear in the lattice dimension. Furthermore, we allow the message space to be ℤp and the randomness distribution to be the discrete Gaussian, both of which are natural choices for the Regev encryption scheme. Finally, in our schemes there is no gap between the size of the message and randomness that an honest prover chooses and the size of which an accepting verifier is convinced. Our constructions use the \\\"MPC-in-the-head\\\" technique of Ishai et al. (STOC 2007). At the heart of our constructions is a protocol for proving that a value is bounded by some publicly known bound. This uses Lagrange's Theorem that states that any positive integer can be expressed as the sum of four squares (an idea previously used by Boudot (EUROCRYPT 2000)), as well as techniques from Cramer and Damgård (CRYPTO 2009).\",\n \"Title: Universally Composable Efficient Multiparty Computation from Threshold Homomorphic Encryption\\nYear: 2003\\n\\nAbstract: We present a new general multiparty computation protocol for the cryptographic scenario which is universally composable - in particular, it is secure against an active and adaptive adversary, corrupting any minority of the parties. The protocol is as efficient as the best known statically secure solutions, in particular the number of bits broadcast (which dominates the complexity) is Omega(nk\\\\C\\\\), where n is the number of parties, k is a security parameter, and \\\\C\\\\ is the size of a circuit doing the desired computation. Unlike previous adaptively secure protocols for the cryptographic model, our protocol does not use non-committing encryption, instead it is based on homomorphic threshold encryption, in particular the Paillier cryptosystem.\",\n \"Title: Non-interactive Proofs for Integer Multiplication\\nYear: 2007\\n\\nAbstract: We present two universally composable and practical protocols by which a dealer can, verifiably and non-interactively, secret-share an integer among a set of players. Moreover, at small extra cost and using a distributed verifier proof, it can be shown in zero-knowledge that three shared integers a,b,csatisfy ab= c. This implies by known reductions non-interactive zero-knowledge proofs that a shared integer is in a given interval, or that one secret integer is larger than another. Such primitives are useful, e.g., for supplying inputs to a multiparty computation protocol, such as an auction or an election. The protocols use various set-up assumptions, but do not require the random oracle model.\",\n \"Title: Scalable Secure Multiparty Computation\\nYear: 2006\\n\\nAbstract: We present the first general protocol for secure multiparty computation which is scalable, in the sense that the amortized work per player does not grow, and in some natural settings even vanishes, with the number of players. Our protocol is secure against an active adversary which may adaptively corrupt up to some constant fraction of the players. The protocol can be implemented in a constant number rounds assuming the existence of a \\\"computationally simple\\\" pseudorandom generator, or in a small non-constant number of rounds assuming an arbitrary pseu- dorandom generator.\",\n \"Title: On the Cost of Reconstructing a Secret, or VSS with Optimal Reconstruction Phase\\nYear: 2001\\n\\nAbstract: Consider a scenario where an l-bit secret has been distributed among n players by an honest dealer using some secret sharing scheme. Then, if all players behave honestly, the secret can be reconstructed in one round with zero error probability, and by broadcasting nl bits. We ask the following question: how close to this ideal can we get if up to t players (but not the dealer) are corrupted by an adaptive, active adversary with unbounded computing power? - and where in addition we of course require that the adversary does not learn the secret ahead of reconstruction time. It is easy to see that t = ⌊(n - 1/2⌋ is the maximal value of t that can be tolerated, and furthermore, we show that the best we can hope for is a one-round reconstruction protocol where every honest player outputs the correct secret or \\\"failure\\\". For any such protocol with failure probability at most 2-Ω(k), we show a lower bound of Ω(nl + kn2) bits on the information communicated. We further show that this is tight up to a constant factor. The lower bound trivially applies as well to VSS schemes, where also the dealer may be corrupt. Using generic methods, the scheme establishing the upper bound can be turned into a VSS with efficient reconstruction. However, the distribution phase becomes very inefficient. Closing this gap, we present a new VSS protocol where the distribution complexity matches that of the previously best known VSS, but where the reconstruction phase meets our lower bound up to a constant factor. The reconstruction is a factor of n better than previous VSS protocols.We show an application of this to multi-party computation with pre-processing, improving the complexity of earlier similar protocols by a factor of n.\",\n \"Title: A length-flexible threshold cryptosystem with applications\\nYear: 2003\\n\\nAbstract: We propose a public-key cryptosystem which is derived from the Paillier cryptosystem. The scheme inherits the attractive homomorphic properties of Paillier encryption. In addition, we achieve two new properties: First, all users can use the same modulus when generating key pairs, this allows more efficient proofs of relations between different encryptions. Second, we can construct a threshold decryption protocol for our scheme that is length-flexible, i.e., it can handle efficiently messages of arbitrary length, even though the public key and the secret key shares held by decryption servers are of fixed size. We show how to apply this cryptosystem to build a self-tallying election scheme with perfect ballot secrecy, and to build a length-flexible mix-net which is universally verifiable, where the size of keys and ciphertexts do not depend on the number of mix servers, and is robust against a corrupt minority.\",\n \"Title: Efficient and secure comparison for on-line auctions\\nYear: 2007\\n\\nAbstract: We propose a protocol for secure comparison of integers based on homomorphic encryption. We also propose a homomorphic encryption scheme that can be used in our protocol and makes it more efficient than previous solutions. Our protocol is well-suited for application in on-line auctions, both with respect to functionality and performance. It minimizes the amount of information bidders need to send, and for comparison of 16 bit numbers with security based on 1024 bit RSA (executed by two parties), our implementation takes 0.28 seconds including all computation and communication. Using precomputation, one can save a factor of roughly 10.\",\n \"Title: Asynchronous Multiparty Computation: Theory and Implementation\\nYear: 2009\\n\\nAbstract: We propose an asynchronous protocol for general multiparty computation. The protocol has perfect security and communication complexity $\\\\mathcal{O}(n^2|C|k)$, where n is the number of parties, |C | is the size of the arithmetic circuit being computed, and k is the size of elements in the underlying field. The protocol guarantees termination if the adversary allows a preprocessing phase to terminate, in which no information is released. The communication complexity of this protocol is the same as that of a passively secure solution up to a constant factor. It is secure against an adaptive and active adversary corrupting less than n /3 players. We also present a software framework for implementation of asynchronous protocols called VIFF (Virtual Ideal Functionality Framework), which allows automatic parallelization of primitive operations such as secure multiplications, without having to resort to complicated multithreading. Benchmarking of a VIFF implementation of our protocol confirms that it is applicable to practical non-trivial secure computations.\",\n \"Title: Verifiable Encryption, Group Encryption, and Their Applications to Separable Group Signatures and Signature Sharing Schemes\\nYear: 2000\\n\\nAbstract: We generalize and improve the security and efficiency of the verifiable encryption scheme of Asokan et al., such that it can rely on more general assumptions, and can be proven secure without assuming random oracles. We extend our basic protocol to a new primitive called verifiable group encryption. We show how our protocols can be applied to construct group signatures, identity escrow, and signature sharing schemes from a wide range of signature, identification, and encryption schemes already in use. In particular, we achieve perfect separability for all these applications, i.e., all participants can choose their signature and encryption schemes and the keys there of independent of each other, even without having these applications in mind.\",\n \"Title: A practical implementation of secure auctions based on multiparty integer computation\\nYear: 2006\\n\\nAbstract: In this paper we consider the problem of constructing secure auctions based on techniques from modern cryptography. We combine knowledge from economics, threshold cryptography and security engineering to implement secure auctions for practical real-world problems.\",\n \"Title: A Statistically-Hiding Integer Commitment Scheme Based on Groups with Hidden Order\\nYear: 2002\\n\\nAbstract: We present a statistically-hiding commitment scheme allowing commitment to arbitrary size integers, based on any (Abelian) group with certain properties, most importantly, that it is hard for the committer to compute its order. We also give efficient zero-knowledge protocols for proving knowledge of the contents of commitments and for verifying multiplicative relations over the integers on committed values. The scheme can be seen as a generalization, with a slight modification, of the earlier scheme of Fujisaki and Okamoto [14]. The reasons we revisit the earlier scheme and give some modification to it are as follows: - The earlier scheme [14] has some gaps in the proof of soundness of the associated protocols, one of which presents a non-trivial problem which, to the best of our knowledge, has remained open until now. We fill all the gaps here using additional ideas including minor modification of the form of a commitment. - Although related works such as [8, 3, 10, 4] do not suffer from the main problem we solve here, the reason for this is that they use \\\"commitments\\\" with a single base (i.e., of form c = gs mod n). Such commitments, however, cannot satisfy the standard hiding property for commitments, and hence protocols using them cannot in general be (honest-verifier) zero-knowledge nor witness indistinguishable. - In a computationally convincing proof of knowledge where the prover produces the common input (which is the type of protocol we look at here), one cannot completely exclude the possibility that a prover manages to produce a common input on which he can cheat easily. This means that the standard definition of proofs of knowledge cannot be satisfied. Therefore we introduce a new definition for computationally convincing proofs of knowledge, designed to handle the case where the common input is chosen by the (possibly cheating) prover. - Our results apply to any group with suitable properties. In particular, they apply to a much larger class of RSA moduli than the safe prime products proposed in [14] - Potential examples include RSA moduli, class groups and, with a slight modification, even non-Abelian groups.Our scheme can replace the earlier one in various other constructions, such as the efficient interval proofs of Boudot [4] and the efficient proofs for the product of two safe primes proposed by Camenisch and Michels [9].\",\n \"Title: Cryptography In the Bounded Quantum-Storage Model\\nYear: 2005\\n\\nAbstract: We initiate the study of two-party cryptographic primitives with unconditional security, assuming that the adversary's quantum memory is of bounded size. We show that oblivious transfer and bit commitment can be implemented in this model using protocols where honest parties need no quantum memory, whereas an adversarial player needs quantum memory of size at least n/2 in order to break the protocol, where n is the number of qubits transmitted. This is in sharp contrast to the classical bounded-memory model, where we can only tolerate adversaries with memory of size quadratic in honest players' memory size. Our protocols are efficient, non-interactive and can be implemented using today's technology. On the technical side, a new entropic uncertainty relation involving min-entropy is established.\",\n \"Title: RFID security: tradeoffs between security and efficiency\\nYear: 2006\\n\\nAbstract: We propose a model and definition for anonymous (group) identification that is well suited for RFID systems. This is based on the definition of Juels and Weis of strong privacy for RFID tags, where we add requirements for completeness and soundness. We also propose a weaker and more realistic definition of privacy. For the case where tags hold independent keys, we prove a conjecture by Juels and Weis, namely in a strongly private and sound RFID system using only symmetric cryptography, a reader must access virtually all keys in the system when reading a tag. It was already known from work by Molnar, Soppera and Wagner that when keys are dependent, the reader only needs to access a logarithmic number of keys, but at a cost in terms of privacy: For that system, privacy is lost if an adversary corrupts just a single tag. We propose protocols offering a new range of tradeoffs between security and efficiency. For instance, the number of keys accessed by a reader to read a tag can be significantly smaller than the number of tags while retaining soundness and privacy, as long as we assume suitable limitations on the adversary.\",\n \"Title: Unconditionally secure constant-rounds multi-party computation for equality, comparison, bits and exponentiation\\nYear: 2006\\n\\nAbstract: We show that if a set of players hold shares of a value $a \\\\in \\\\mathbb{F}_p $ for some prime p (where the set of shares is written [a]p), it is possible to compute, in constant rounds and with unconditional security, sharings of the bits of a, i.e., compute sharings [a0]p, ..., [aℓ−−1]p such that ℓ = ⌈ log2p ⌉, a0,...,al−1∈{0,1} and a = ∑i=0ℓ−−1ai 2i. Our protocol is secure against active adversaries and works for any linear secret sharing scheme with a multiplication protocol. The complexity of our protocol is $\\\\mathcal{O}(l {\\\\rm log} l)$ invocations of the multiplication protocol for the underlying secret sharing scheme, carried out in $\\\\mathcal{O}(1)$ rounds. This result immediately implies solutions to other long-standing open problems such as constant-rounds and unconditionally secure protocols for deciding whether a shared number is zero, comparing shared numbers, raising a shared number to a shared exponent and reducing a shared number modulo a shared modulus.\",\n \"Title: Expanding Pseudorandom Functions; or: From Known-Plaintext Security to Chosen-Plaintext Security\\nYear: 2002\\n\\nAbstract: Given any weak pseudorandom function, we present a general and efficient technique transforming such a function to a new weak pseudorandom function with an arbitrary length output. This implies, among other things, an encryption mode for block ciphers. The mode is as efficient as known (and widely used) encryption modes as CBC mode and counter (CTR) mode, but is provably secure against chosen-plaintext attack (CPA) already if the underlying symmetric cipher is secure against known-plaintext attack (KPA). We prove that CBC, CTR and Jutla's integrity aware modes do not have this property. In particular, we prove that when using a KPA secure block cipher, then: CBC mode is KPA secure, but need not be CPA secure, Jutla's modes need not be CPA secure, and CTR mode need not be even KPA secure. The analysis is done in a concrete security framework.\",\n \"Title: Proofs of Partial Knowledge and Simplified Design of Witness Hiding Protocols\\nYear: 1994\\n\\nAbstract: Suppose we are given a proof of knowledge P in which a prover demonstrates that he knows a solution to a given problem instance. Suppose also that we have a secret sharing scheme S on n participants. Then under certain assumptions on P and S, we show how to transform P into a witness indistinguishable protocol, in which the prover demonstrates knowledge of the solution to some subset of n problem instances out of a collection of subsets denned by S. For example, using a threshold scheme, the prover can show that he knows at least d out of n solutions without revealing which d instances are involved. If the instances axe independently generated, we get a witness hiding protocol, even if P did not have this property. Our results can be used to efficiently implement general forms of group oriented identification and signatures. Our transformation produces a protocol with the same number of rounds as P and communication complexity n times that of P. Our results use no unproven complexity assumptions.\",\n \"Title: Efficient, robust and constant-round distributed RSA key generation\\nYear: 2010\\n\\nAbstract: We present the first protocol for distributed RSA key generation which is constant round, secure against malicious adversaries and has a negligibly small bound on the error probability, even using only one iteration of the underlying primality test on each candidate number.\",\n \"Title: Unfair Noisy Channels and Oblivious Transfer\\nYear: 2004\\n\\nAbstract: In a paper from EuroCrypt'99, Damgard, Kilian and Salvail show various positive and negative results on constructing Bit Commitment (BC) and Oblivious Transfer (OT) from Unfair Noisy Channels (UNC), i.e., binary symmetric channels where the error rate is only known to be in a certain interval and can be chosen adversarily. They also introduce a related primitive called PassiveUNC. We prove in this paper that any OT protocol that can be constructed based on a PassiveUNC and is secure against a passive adversary can be transformed using a generic \\\"compiler\\\" into an OT protocol based on a UNC which is secure against an active adversary. Apart from making positive results easier to prove in general, this also allows correcting a problem in the EuroCrypt'99 paper: There, a positive result was claimed on constructing from UNC an OT that is secure against active cheating. We point out that the proof sketch given for this was incomplete, and we show that a correct proof of a much stronger result follows from our general compilation result and a new technique for transforming between weaker versions of OT with different parameters.\",\n \"Title: Fast and secure immunization against adaptive man-in-the-middle impersonation\\nYear: 1997\\n\\nAbstract: We present a simple method for constructing identification schemes resilient against impersonation and man-in-the-middle attacks. Though zero-knowledge or witness hiding protocols are known to withstand attacks of the first kind, all such protocols previously proposed suffer from a weakness observed by Bengio et al.: a malicious verifier may simply act as a moderator between the prover and yet another verifier, thus enabling the malicious verifier to pass as the prover. We exhibit a general class of identification schemes that can be efficiently and securely tranformed into identification schemes withstanding an adaptive man-in-the-middle attacker. The complexity of the resulting (witness hiding) schemes is roughly twice that of the originals. Basically, any three-move, public coin identification scheme that is zero knowledge against the honest verifier and that is secure against passive impersonation attacks, is eligible for our transformation. This indicates that we need only seemlingly weak cryptographic intractability assumptions to construct a practical identification scheme resisting adative man-in-the-middle impersonation attacks. Moreover, the required primitive protocols can efficiently be constructed under the factoring or discrete logarithm assumptions.\",\n \"Title: Scalable and unconditionally secure multiparty computation\\nYear: 2007\\n\\nAbstract: We present a multiparty computation protocol that is unconditionally secure against adaptive and active adversaries, with communication complexity O(Cn)k + O(Dn2)k + poly(nκ), where C is the number of gates in the circuit, n is the number of parties, k is the bit-length of the elements of the field over which the computation is carried out, D is the multiplicative depth of the circuit, and κ is the security parameter. The corruption threshold is t n/3. For passive security the corruption threshold is t n/2 and the communication complexity is O(nC)k. These are the first unconditionally secure protocols where the part of the communication complexity that depends on the circuit size is linear in n. We also present a protocol with threshold t n/2 and complexity O(Cn)k+poly(nκ) based on a complexity assumption which, however, only has to hold during the execution of the protocol - that is, the protocol has so called everlasting security.\",\n \"Title: Commitment Schemes and Zero-Knowledge Protocols\\nYear: 1998\\n\\nAbstract: Abstract This article is an introduction to two fundamental primitives in cryptographic protocol theory: commitment,schemes and zero-knowledge protocols, and a survey of some new and old results on their existence and the connection between them. 1 What’s in this article?\",\n \"Title: Client/Server Tradeoffs for Online Elections\\nYear: 2002\\n\\nAbstract: We present various trade offs for voting schemes which, compared to known solutions, allow voters to do less work at the expense of more work done by the tallying servers running the election. One such scheme produces ballots of essentially minimal size while keeping the work load on the tally servers on a practical level. Another type of trade off leads to a voting scheme that remains secure, even if an adversary can monitor all client machines used by voters to participate. This comes at the price of introducing an additional party who is trusted to carry out registration of voters correctly.\",\n \"Title: Essentially Optimal Universally Composable Oblivious Transfer\\nYear: 2008\\n\\nAbstract: Oblivious transfer is one of the most important cryptographic primitives, both for theoretical and practical reasons and several protocols were proposed during the years. We propose a protocol which is simultaneously optimal on the following list of parameters: Security: it has universal composition. Trust in setup assumptions: only one of the parties needs to trust the setup (and some setup is needed for UC security). Trust in computational assumptions: only one of the parties needs to trust a computational assumption. Round complexity: it uses only two rounds. Communication complexity: it communicates $\\\\mathcal{O}(1)$ group elements to transfer one out of two group elements. The Big-O notation hides 32, meaning that the communication is probably not optimal, but is essentially optimal in that the overhead is at least constant. Our construction is based on pairings, and we assume the presence of a key registration authority.\",\n \"Title: DDH-Like assumptions based on extension rings\\nYear: 2012\\n\\nAbstract: We introduce and study a new type of DDH-like assumptions based on groups of prime order q . Whereas standard DDH is based on encoding elements of $\\\\mathbb{F}_{q}$ \\\"in the exponent\\\" of elements in the group, we ask what happens if instead we put in the exponent elements of the extension ring $R_f= \\\\mathbb{F}_{q}[X]/(f)$ where f is a degree-d polynomial. The decision problem that follows naturally reduces to the case where f is irreducible. This variant is called the d -DDH problem, where 1-DDH is standard DDH. We show in the generic group model that d -DDH is harder than DDH for d 1 and that we obtain, in fact, an infinite hierarchy of progressively weaker assumptions whose complexities lie \\\"between\\\" DDH and CDH. This leads to a large number of new schemes because virtually all known DDH-based constructions can very easily be upgraded to be based on d -DDH. We use the same construction and security proof but get better security and moreover, the amortized complexity (e.g, computation per encrypted bit) is the same as when using DDH. We also show that d -DDH, just like DDH, is easy in bilinear groups. We therefore suggest a different type of assumption, the d -vector DDH problems (d -VDDH), which are based on f (X )=X d , but with a twist to avoid problems with reducible polynomials. We show in the generic group model that d -VDDH is hard in bilinear groups and that the problems become harder with increasing d . We show that hardness of d -VDDH implies CCA-secure encryption, efficient Naor-Reingold style pseudorandom functions, and auxiliary input secure encryption. This can be seen as an alternative to the known family of k -LIN assumptions.\",\n \"Title: Implementing AES via an actively/covertly secure dishonest-majority MPC protocol\\nYear: 2012\\n\\nAbstract: We describe an implementation of the protocol of Damgård, Pastro, Smart and Zakarias (SPDZ/Speedz) for multi-party computation in the presence of a dishonest majority of active adversaries. We present a number of modifications to the protocol; the first reduces the security to covert security, but produces significant performance enhancements; the second enables us to perform bit-wise operations in characteristic two fields. As a bench mark application we present the evaluation of the AES cipher, a now standard bench marking example for multi-party computation. We need examine two different implementation techniques, which are distinct from prior MPC work in this area due to the use of MACs within the SPDZ protocol. We then examine two implementation choices for the finite fields; one based on finite fields of size 28 and one based on embedding the AES field into a larger finite field of size 240.\",\n \"Title: Zero-Knowledge Authentication Scheme with Secret Key Exchange (Extended Abstract)\\nYear: 1988\\n\\nAbstract: In this note we first develop a new computationally zero-knowledge interactive proof system of knowledge, which then is modified\\n into an authentication scheme with secret key exchange for subsequent conventional encryption. Implemented on a standard 32-bit\\n chip or similar, the whole protocol, which involves mutual identification of two users, exchange of a random common secret\\n key and verification of certificates for the public keys (RSA, 512 bits) takes less than 0.7 seconds.\",\n \"Title: Universally Composable Multiparty Computation with Partially Isolated Parties\\nYear: 2007\\n\\nAbstract: It is well known that universally composable multiparty computation cannot, in general, be achieved in the standard model without setup assumptions when the adversary can corrupt an arbitrary number of players. One way to get around this problem is by having a trusted third party generate some global setup such as a common reference string (CRS) or a public key infrastructure (PKI) . The recent work of Katz shows that we may instead rely on physical assumptions, and in particular tamper-proof hardware tokens . In this paper, we consider a similar but strictly weaker physical assumption. We assume that a player (Alice) can partially isolate another player (Bob) for a brief portion of the computation and prevent Bob from communicating more than some limited number of bits with the environment. For example, isolation might be achieved by asking Bob to put his functionality on a tamper-proof hardware token and assuming that Alice can prevent this token from communicating to the outside world. Alternatively, Alice may interact with Bob directly but in a special office which she administers and where there are no high-bandwidth communication channels to the outside world. We show that, under standard cryptographic assumptions, such physical setup can be used to UC-realize any two party and multiparty computation in the presence of an active and adaptive adversary corrupting any number of players. We also consider an alternative scenario, in which there are some trusted third parties but no single such party is trusted by all of the players. This compromise allows us to significantly limit the use of the physical set-up and hence might be preferred in practice.\",\n \"Title: Bounded Tamper Resilience: How to go beyond the Algebraic Barrier.\\nYear: 2013\\n\\nAbstract: Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary in case of arbitrary key relations, as otherwise a generic attack of Gennaro et al. (TCC 2004) shows how to recover the key of almost any cryptographic primitive. We describe our contributions in more detail below. (1) We show that standard ID and signature schemes constructed from a large class of $$\\\\\\\\Sigma $$Σ-protocols (including the Okamoto scheme, for instance) are secure even if the adversary can arbitrarily tamper with the prover's state a bounded number of times and obtain some bounded amount of leakage. Interestingly, for the Okamoto scheme we can allow also independent tampering with the public parameters. (2) We show a bounded tamper and leakage resilient CCA-secure public key cryptosystem based on the DDH assumption. We first define a weaker CCA-like security notion that we can instantiate based on DDH, and then we give a general compiler that yields CCA security with tamper and leakage resilience. This requires a public tamper-proof common reference string. (3) Finally, we explain how to boost bounded tampering and leakage resilience [as in (1) and (2) above] to continuous tampering and leakage resilience, in the so-called floppy model where each user has a personal hardware token (containing leak- and tamper-free information) which can be used to refresh the secret key. We believe that bounded tampering is a meaningful and interesting alternative to avoid known impossibility results and can provide important insights into the security of existing standard cryptographic schemes.\",\n \"Title: Multiparty Computation from Somewhat Homomorphic Encryption.\\nYear: 2011\\n\\nAbstract: We propose a general multiparty computation protocol secure against an active adversary corrupting up to n-1 of the n players. The protocol may be used to compute securely arithmetic circuits over any finite field F.. Our protocol consists of a preprocessing phase that is both independent of the function to be computed and of the inputs, and a much more efficient online phase where the actual computation takes place. The online phase is unconditionally secure and has total computational (and communication) complexity linear in n, the number of players, where earlier work was quadratic in n. Moreover, the work done by each player is only a small constant factor larger than what one would need to compute the circuit in the clear. We show this is optimal for computation in large fields. In practice, for 3 players, a secure 64-bit multiplication can be done in 0.05 ms. Our preprocessing is based on a somewhat homomorphic cryptosystem. We extend a scheme by Brakerski et al., so that we can perform distributed decryption and handle many values in parallel in one ciphertext. The computational complexity of our preprocessing phase is dominated by the public-key operations, we need O(n(2)/s) operations per secure multiplication where s is a parameter that increases with the security parameter of the cryptosystem. Earlier work in this model needed Omega(n(2)) operations. In practice, the preprocessing prepares a secure 64-bit multiplication for 3 players in about 13 ms.\",\n \"Title: Multiparty Computation from Threshold Homomorphic Encryption\\nYear: 2001\\n\\nAbstract: We introduce a new approach to multiparty computation (MPC) basing it on homomorphic threshold crypto-systems. We show that given keys for any sufficiently efficient system of this type, general MPC protocols for n parties can be devised which are secure against an active adversary that corrupts any minority of the parties. The total number of bits broadcast is O(nk|C|), where k is the security parameter and |C| is the size of a (Boolean) circuit computing the function to be securely evaluated. An earlier proposal by Franklin and Haber with the same complexity was only secure for passive adversaries, while all earlier protocols with active security had complexity at least quadratic in n. We give two examples of threshold cryptosystems that can support our construction and lead to the claimed complexities.\",\n \"Title: Secret-Key Zero-Knowlegde and Non-interactive Verifiable Exponentiation\\nYear: 2004\\n\\nAbstract: We consider a new model for non-interactive zero-knowledge where security is not based on a common reference string, but where prover and verifier are assumed to possess appropriately correlated secret keys. We present efficient proofs for equality of discrete logarithms in this model with unconditional soundness and zero-knowledge. This has immediate applications to non-interactive verification of undeniable signatures and pseudorandom function values. Another application is the following: a set of 1 servers, of which less than l/2 are corrupt, hold shares of a secret integer s. A client C specifies g in some finite group G, and the servers want to allow the client to compute g(s) non-interactively, i.e., by sending information to C only once. This has immediate applications in threshold cryptography. Using our proof system, the problem can be solved as efficiently as the fastest previous solutions that either required interaction or had to rely on the random oracle model for a proof of security. The price we pay is the need to establish the secret key material once and for all. We present an alternative solution to the problem that is also non-interactive and where clients need no secret keys. This comes at the expense of more communication and the assumption that less than l/3 of the servers are corrupt.\",\n \"Title: New Generation of Secure and Practical RSA-Based Signatures\\nYear: 1996\\n\\nAbstract: For most digital signature schemes used in practice, such as ISO9796/RSA or DSA, it has only been shown that certain plausible cryptographic assumptions, such as the difficulty of factoring integers, computing discrete logarithms or the collision-intractability of certain hash-functions are necessary for the security of the scheme, while their sufficiency is, strictly speaking, an open question. A clear advantage of such schemes over many signature schemes with security proven relative to such common cryptographic assumptions, is their efficiency: as a result of their relatively weak requirements regarding computation, bandwidth and storage, these schemes have so far beaten proven secure schemes in practice. Our aim is to contribute to the bridging of the gap that seems to exist between the theory and practice of digital signature schemes. We present a digital signature that offers both proven security and practical value. More precisely, under an appropriate assumption about RSA, the scheme is proven to be not existentially forgeable under adaptively chosen message attacks. We also identify some applications where our scheme can be conveniently implemented using dedicated smartcards that are available today.\",\n \"Title: A Generalisation, a Simplification and Some Applications of Paillier's Probabilistic Public-Key System\\nYear: 2001\\n\\nAbstract: We propose a generalisation of Paillier's probabilistic public key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without loosing the homomorphic property. We show that the generalisation is as secure as Paillier's original system. We construct a threshold variant of the generalised scheme as well as zero-knowledge protocols to show that a given ciphertext encrypts one of a set of given plaintexts, and protocols to verify multiplicative relations on plaintexts. We then show how these building blocks can be used for applying the scheme to efficient electronic voting.This reduces dramatically the work needed to compute the final result of an election, compared to the previously best known schemes.W e show how the basic scheme for a yes/no vote can be easily adapted to casting a vote for up to t out of L candidates. The same basic building blocks can also be adapted to provide receipt-free elections, under appropriate physical assumptions. The scheme for 1 out of L elections can be optimised such that for a certain range of parameter values, a ballot has size only O(log L) bits.\",\n \"Title: Multiparty Computations Ensuring Privacy of Each Party's Input and Correctness of the Result\\nYear: 1987\\n\\nAbstract: A protocol is presented that allows a set of parties to collectively perform any agreed computation, where every party is able to choose secret inputs and verify that the resulting output is correct, and where all secret inputs are optimally protected. The protocol has the following properties: 驴 One participant is allowed to hide his secrets unconditionally, i.e. the protocol releases no Shannon information about these secrets. This means that a participant with bounded resources can perform computations securely with a participant who may have unlimited computing power. To the best of our knowledge, our protocol is the first of its kind to provide this possibility. 驴 The cost of our protocol is linear in the number of gates in a circuit performing the computation, and in the number of participants. We believe it is conceptually simpler and more efficient than other protocols solving related problems ([Y1], [GoMiWi] and [GaHaYu]). It therefore leads to practical solutions of problems involving small circuits. 驴 The protocol is openly verifiable, i.e. any number of people can later come in and rechallenge any participant to verify that no cheating has occurred. 驴 The protocol is optimally secure against conspiracies: even if n - 1 out of the n participants collude, they will not find out more about the remaining participants' secrets than what they could already infer from their own input and the public output. 驴 Each participant has a chance of undetected cheating that is only exponentially small in the amount of time and space needed for the protocol. 驴 The protocol adapts easily, and with negligible extra cost, to various additional requirements, e.g. making part of the output private to some participant, ensuring that the participants learn the output simultaneously, etc. 驴 Participants can prove relations between data used in different instances of the protocol, even if those instances involve different groups of participants. For example, it can be proved that the output of one computation was used as input to another, without revealing more about this data. 驴 The protocol can be usen as an essential tool in proving that all languages in IP have zero knowledge proof systems, i.e. any statement which can be proved interactively can also be proved in zero knowledge.The rest of this paper is organised as follows: First we survey some related results. Then Section 2 gives an intuitive introduction to the protocol. In Section 3, we present one of the main tools used in this paper: bit commitment schemes. Sections 4 and 5 contain the notation, terrninology, etc. used in the paper. In Section 6, the protocol is presented, along with proofs of its security and correctness. In Section 7, we show how to adapt the protocol to various extra requirements and discuss some generalisations and optimisations. Finally, Section 8 contains some remarks on how to construct zero knowledge proof systems for any language in IP.\",\n \"Title: Interactive Hashing can Simplify Zero-Knowledge Protocol Design Without Computational Assumptions (Extended Abstract)\\nYear: 1993\\n\\nAbstract: We show that any 3-round protocol (in general, any bounded round protocol) in which the verifier sends only random bits, and which is zero-knowledge against an honest verifier can be transformed into a protocol that is zero-knowledge in general. The transformation is based on the interactive hashing technique of Naor, Ostrovsky, Venkatesan and Yung. No assumption is made on the computing power of prover or verifier, and the transformation therefore is valid in both the proof and argument model, and does not rely on any computational assumptions such as the existence of one-way permutations. The technique is also applicable to proofs of knowledge. The transformation preserves perfect and statistical zero-knowledge. As corollaries, we show first a generalization of a result by Damg氓rd on construction of bit-commitments from zero-knowledge proofs. Other corollaries give results on noninteractive zero-knowledge, one-sided proof systems, and black-box simulation.\",\n \"Title: Threshold decryption and zero-knowledge proofs for lattice-based cryptosystems\\nYear: 2010\\n\\nAbstract: We present a variant of Regev’s cryptosystem first presented in [Reg05], but with a new choice of parameters. By a recent classical reduction by Peikert we prove the scheme semantically secure based on the worst-case lattice problem GapSVP. From this we construct a threshold cryptosystem which has a very efficient and non-interactive decryption protocol. We prove the threshold cryptosystem secure against passive adversaries corrupting all but one of the players, and againts active adversaries corrupting less than one third of the players. We also describe how one can build a distributed key generation protocol. In the final part of the paper we show how one can, in zero-knowledge - prove knowledge of the plaintext contained in a given ciphertext from Regev’s original cryptosystem or our variant. The proof is of size only a constant times the size of the public key.\",\n \"Title: On the Amortized Complexity of Zero-Knowledge Protocols\\nYear: 2014\\n\\nAbstract: We propose a general technique that allows improving the complexity of zero-knowledge protocols for a large class of problems where previously the best known solution was a simple cut-and-choose style protocol, i.e., where the size of a proof for problem instance x and error probability 2 n was O (| x | n ) bits. By using our technique to prove n instances simultaneously, we can bring down the proof size per instance to O (| x |+ n ) bits for the same error probability while using no computational assumptions. Examples where our technique applies include proofs for quadratic residuosity, proofs of subgroup membership and knowledge of discrete logarithms in groups of unknown order, interval proofs of the latter, and proofs of plaintext knowledge for various types of homomorphic encryption schemes. We first propose our protocols as Σ -protocols and extend them later to zero-knowledge proofs of knowledge.\",\n \"Title: Constant-round multiparty computation using a black-box pseudorandom generator\\nYear: 2005\\n\\nAbstract: We present a constant-round protocol for general secure multiparty computation which makes a black-box use of a pseudorandom generator. In particular, the protocol does not require expensive zero-knowledge proofs and its communication complexity does not depend on the computational complexity of the underlying cryptographic primitive. Our protocol withstands an active, adaptive adversary corrupting a minority of the parties. Previous constant-round protocols of this type were only known in the semi-honest model or for restricted classes of functionalities.\",\n \"Title: Improved Non-committing Encryption Schemes Based on a General Complexity Assumption\\nYear: 2000\\n\\nAbstract: Non-committing encryption enables the construction of multiparty computation protocols secure against an adaptive adversary in the computational setting where private channels between players are not assumed. While any non-committing encryption scheme must be secure in the ordinary semantic sense, the converse is not necessarily true. We propose a construction of non-committing encryption that can be based on any public-key system which is secure in the ordinary sense and which has an extra property we call simulatability. This generalises an earlier scheme proposed by Beaver based on the Diffie-Hellman problem, and we propose another implementation based on RSA. In a more general setting, our construction can be based on any collection of trapdoor permutations with a certain simulatability property. This offers a considerable efficiency improvement over the first non-committing encryption scheme proposed by Canetti et al. Finally, at some loss of efficiency, our scheme can be based on general collections of trapdoor permutations without the simulatability assumption, and without the common-domain assumption of Canetti et al. In showing this last result, we identify and correct a bug in a key generation protocol from Canetti et al.\",\n \"Title: Simplified threshold RSA with adaptive and proactive security\\nYear: 2006\\n\\nAbstract: We present the currently simplest, most efficient, optimally resilient, adaptively secure, and proactive threshold RSA scheme. A main technical contribution is a new rewinding strategy for analysing threshold signature schemes. This new rewinding strategy allows to prove adaptive security of a proactive threshold signature scheme which was previously assumed to be only statically secure. As a separate contribution we prove that our protocol is secure in the UC framework.\",\n \"Title: From passive to covert security at low cost\\nYear: 2010\\n\\nAbstract: Aumann and Lindell defined security against covert attacks, where the adversary is malicious, but is only caught cheating with a certain probability. The idea is that in many real-world cases, a large probability of being caught is sufficient to prevent the adversary from trying to cheat. In this paper, we show how to compile a passively secure protocol for honest majority into one that is secure against covert attacks, again for honest majority and catches cheating with probability 1/4. The cost of the modified protocol is essentially twice that of the original plus an overhead that only depends on the number of inputs.\",\n \"Title: On the Theory and Practice of Personal Digital Signatures\\nYear: 2009\\n\\nAbstract: We take a step towards a more realistic modeling of personal digital signatures, where a human user, his mobile equipment, his PC and a server are all considered as independent players in the protocol, and where only the human user is assumed incorruptible. We then propose a protocol for issuing digital signatures on behalf of the user. This protocol is proactively UC-secure assuming at most one player is corrupted in every operational phase. In more practical terms, this means that one can securely sign using terminals (PC's) that are not necessarily trusted, as long as the mobile unit and the PC are not both corrupted at the same time. In other words, our solution cannot be broken by phising or key-logging via the PC. The protocol allows for mobile units with very small computing power by securely outsourcing computation to the PC and also allows usage of any PC that can communicate properly. Finally, we report on the results of a prototype implementation of our solution.\",\n \"Title: Efficient and Provable Security Amplifications\\nYear: 1996\\n\\nAbstract: Even, Goldreich and Micali showed at Crypto''89 that the existence of signature schemes secure against known message attacks implies the existence of schemes secure against adaptively chosen message attacks. Unfortunately, this transformation leads to a rather impractical scheme. We exhibit a similar security amplification, which takes the given scheme to a new signature scheme that is not even existentially forgeable under adaptively chosen message attacks. Additionally, however, our transformation will be practical: The complexity of the resulting scheme is twice that of the original scheme. The principles of both transformations carry over to block encryption systems. It is shown how they can be used to convert a block encryption system secure against known plaintext attacks to a system secure against chosen plaintext attacks. For both schemes it is shown that if the transformed scheme can be broken given a number, $T$, of encryptions of adaptively chosen plaintexts, then the original scheme can be broken given encryptions of $T$ uniformly chosen plaintexts. In this case, however, the application of the technique of Even, Goldreich and Micali leads to the more efficient scheme. The transformed scheme has the same key length as the original, and ciphertexts are doubled in length. As an example, when applied to DES the transformed scheme is secure against differential cryptanalysis, which relies on the ability to get encryptions of plaintext pairs with proper differences.\",\n \"Title: Perfectly secure multiparty computation and the computational overhead of cryptography\\nYear: 2010\\n\\nAbstract: We study the following two related questions: What are the minimal computational resources required for general secure multiparty computation in the presence of an honest majority? What are the minimal resources required for two-party primitives such as zero-knowledge proofs and general secure two-party computation? We obtain a nearly tight answer to the first question by presenting a perfectly secure protocol which allows n players to evaluate an arithmetic circuit of size s by performing a total of $\\\\mathcal{O}(s\\\\log s\\\\log^2 n)$ arithmetic operations, plus an additive term which depends (polynomially) on n and the circuit depth, but only logarithmically on s. Thus, for typical large-scale computations whose circuit width is much bigger than their depth and the number of players, the amortized overhead is just polylogarithmic in n and s. The protocol provides perfect security with guaranteed output delivery in the presence of an active, adaptive adversary corrupting a (1/3−ε) fraction of the players, for an arbitrary constant ε0 and sufficiently large n. The best previous protocols in this setting could only offer computational security with a computational overhead of poly(k,logn,logs), where k is a computational security parameter, or perfect security with a computational overhead of $\\\\mathcal{O}(n\\\\log n)$. We then apply the above result towards making progress on the second question. Concretely, under standard cryptographic assumptions, we obtain zero-knowledge proofs for circuit satisfiability with 2−k soundness error in which the amortized computational overhead per gate is only polylogarithmic in k, improving over the ω(k) overhead of the best previous protocols. Under stronger cryptographic assumptions, we obtain similar results for general secure two-party computation.\",\n \"Title: Efficient Zero-Knowledge Proofs of Knowledge Without Intractability Assumptions\\nYear: 2000\\n\\nAbstract: . We initiate the investigation of the class of relations that admit extremely efficient perfectzero knowledge proofs of knowledge: constant number of rounds, communication linear in the length ofthe statement and the witness, and negligible knowledge error. In its most general incarnation, our resultsays that for relations that have a particular three-move honest-verifier zero-knowledge (HVZK) proofof knowledge, and which admit a particular three-move HVZK proof of knowledge for an...\",\n \"Title: Share conversion, pseudorandom secret-sharing and applications to secure computation\\nYear: 2005\\n\\nAbstract: We present a method for converting shares of a secret into shares of the same secret in a different secret-sharing scheme using only local computation and no communication between players. In particular, shares in a replicated scheme based on a CNF representation of the access structure can be converted into shares from any linear scheme for the same structure. We show how this can be combined with any pseudorandom function to create, from initially distributed randomness, any number of Shamir secret-sharings of (pseudo)random values without communication. We apply this technique to obtain efficient non-interactiveprotocols for secure computation of low-degree polynomials, which in turn give rise to other applications in secure computation and threshold cryptography. For instance, we can make the Cramer-Shoup threshold cryptosystem by Canetti and Goldwasser fully non-interactive, or construct non-interactive threshold signature schemes secure without random oracles. The latter solutions are practical only for a relatively small number of players. However, in our main applications the number of players is typically small, and furthermore it can be argued that no solution that makes a black-box use of a pseudorandom function can be more efficient.\",\n \"Title: How to Split a Shared Secret into Shared Bits in Constant-Round\\nYear: 2005\\n\\nAbstract: We show that if a set of players hold shares of a value a ∈ Zp for some prime p (where the set of shares is written (a)p), it is possible to compute, in constant round and with unconditional security, sharings of the bits of a, i.e. compute sharings (a0)p, . . . ,(aℓ 1)p such\",\n \"Title: Multiple Encryption with Minimum Key\\nYear: 1995\\n\\nAbstract: In this paper we consider multiple encryption schemes built from conventional cryptosystems such as DES. The existing schemes are either vulnerable to variants of meet in the middle attacks, i.e. they do not provide security of the full key or there is no proof that the schemes are as secure as the underlying cipher. We propose a new variant of two-key triple encryption which is not vulnerable to the meet in the middle attack and which uses a minimum amount of key. We can prove a connection between the security of our system and the security of the underlying block cipher.\",\n \"Title: On the amortized complexity of zero knowledge protocols for multiplicative relations\\nYear: 2012\\n\\nAbstract: We present a protocol that allows to prove in zero-knowledge that committed values xi, yi, zi, i=1,…,l satisfy xiyi=zi, where the values are taken from a finite field. For error probability 2−u the size of the proof is linear in u and only logarithmic in l. Therefore, for any fixed error probability, the amortized complexity vanishes as we increase l. In particular, when the committed values are from a field of small constant size, we improve complexity of previous solutions by a factor of l. Assuming preprocessing, we can make the commitments (and hence the protocol itself) be information theoretically secure. Using this type of commitments we obtain, in the preprocessing model, a perfect zero-knowledge interactive proof for circuit satisfiability of circuit C where the proof has size O(|C|). We then generalize our basic scheme to a protocol that verifies l instances of an algebraic circuit D over K with v inputs, in the following sense: given committed values xi,j and zi, with i=1,…,l and j=1,…,v, the prover shows that D(xi,1,…,xi,v)=zi for i=1,…,l. The interesting property is that the amortized complexity of verifying one circuit only depends on the multiplicative depth of the circuit and not the size. So for circuits with small multiplicative depth, the amortized cost can be asymptotically smaller than the number of multiplications in D. Finally we look at commitments to integers, and we show how to implement information theoretically secure homomorphic commitments to integer values, based on preprocessing. After preprocessing, they require only a constant number of multiplications per commitment. We also show a variant of our basic protocol, which can verify l integer multiplications with low amortized complexity. This protocol also works for standard computationally secure commitments and in this case we improve on security: whereas previous solutions with similar efficiency require the strong RSA assumption, we only need the assumption required by the commitment scheme itself, namely factoring.\",\n \"Title: Theory and practice of multiparty computation\\nYear: 2006\\n\\nAbstract: This is a short summary of the invited talk given by the author at the SCN conference.\",\n \"Title: New convertible undeniable signature schemes\\nYear: 1996\\n\\nAbstract: Undeniable signatures are like ordinary digital signatures, except that testing validity of a signature requires interaction with the signer. This gives the signer additional control over who will benefit from being convinced by a signature, and is particularly relevant when signing sensitive, non-public data. Convertible undeniable signatures offer additional flexibility in that there is a separate verification key that can be used to verify a signature (without interaction). This allows the signer to delegate the ability to verify signatures to one or more participants, and ultimately to convert all signatures to ordinary ones by making the verification key public. While provably secure theoretical solutions exist for convertible schemes, earlier practical schemes proposed have either been broken or their status as far as security is concerned is very unclear. In this paper, we present two new convertible schemes, in which forging signatures is provably equivalent to forging El Gamal signatures. The difficulty of verifying signatures without interacting with the signer is based on the factoring problem for one of the schemes and on the Diffie-Hellman problem for the other scheme.\",\n \"Title: Multiparty Unconditionally Secure Protocols (Abstract)\\nYear: 1987\\n\\nAbstract: It has been shown previously how almost any multiparty protocol problem can be solved. All the constructions suggested so far rely on trapdoor one-way functions, and therefore must assume essentially that public key cryptography is possible. It has also been shown that unconditional protection of a single designated participant is all that can be achieved under that model. Assuming only authenticated secrecy channels between pairs of participants, we show that essentially any multiparty protocol problem can be solved. Such a model actually implies the further requirement that less than one third of the participants deviate from the protocol. The techniques presented do not, however, rely on any cryptographic assumptions; they achieve the optimal result and provide security as good as the secrecy and authentication of the channeis used. Moreover, the constructions have a built-in fault tolerance: once the participants have sent messages committing themselves to the secrets they will use in the protocol, there is no way less than a third of them can stop the protocol from completing correctly. Our technique relies on the so called key-safeguarding or secret-sharing schemes proposed by Blakley and Shamir as basic building blocks. The usefulness of their homomorphic structure was observed by Benaloh, who proposed techniques very similar to ours.\",\n \"Title: Secure two-party computation with low communication\\nYear: 2012\\n\\nAbstract: We propose a 2-party UC-secure protocol that can compute any function securely. The protocol requires only two messages, communication that is poly-logarithmic in the size of the circuit description of the function, and the workload for one of the parties is also only poly-logarithmic in the size of the circuit. This implies, for instance, delegatable computation that requires no expensive off-line phase and remains secure even if the server learns whether the client accepts its results. To achieve this, we define two new notions of extractable hash functions, propose an instantiation based on the knowledge of exponent in an RSA group, and build succinct zero-knowledge arguments in the CRS model.\",\n \"Title: Linear integer secret sharing and distributed exponentiation\\nYear: 2006\\n\\nAbstract: We introduce the notion of Linear Integer Secret-Sharing (LISS) schemes, and show constructions of such schemes for any access structure. We show that any LISS scheme can be used to build a secure distributed protocol for exponentiation in any group. This implies, for instance, distributed RSA protocols for arbitrary access structures and with arbitrary public exponents.\",\n \"Title: Scalable Multiparty Computation with Nearly Optimal Work and Resilience\\nYear: 2008\\n\\nAbstract: We present the first general protocol for secure multiparty computation in which the totalamount of work required by nplayers to compute a function fgrows only polylogarithmically with n(ignoring an additive term that depends on nbut not on the complexity of f). Moreover, the protocol is also nearly optimal in terms of resilience, providing computational security against an active, adaptive adversary corrupting a (1/2 茂戮驴 茂戮驴) fraction of the players, for an arbitrary 茂戮驴 0.\",\n \"Title: Efficient algorithms for the gcd and cubic residuosity in the ring of Eisenstein integers\\nYear: 2003\\n\\nAbstract: We present simple and efficient algorithms for computing the gcd and cubic residuosity in the ring of Eisenstein integers, Z[@z], i.e. the integers extended with @z, a complex primitive third root of unity. The algorithms are similar and may be seen as generalisations of the binary integer gcd and derived Jacobi symbol algorithms. Our algorithms take time O(n^2) for n-bit input. For the cubic residuosity problem this is an improvement from the known results based on the Euclidean algorithm, and taking time O(n@?M(n)), where M(n) denotes the complexity of multiplying n-bit integers. For the gcd problem our algorithm is simpler and faster than an earlier algorithm of complexity O(n^2). The new algorithms have applications in practical primality tests and the implementation of cryptographic protocols.\",\n \"Title: Quantum Communication Attacks on Classical Cryptographic Protocols - (Invited Talk)\\nYear: 2011\\n\\nAbstract: In the literature on cryptographic protocols, it has been studied several times what happens if a classical protocol is attacked\\n by a quantum adversary. Usually, this is taken to mean that the adversary runs a quantum algorithm, but communicates classically\\n with the honest players. In several cases, one can show that the protocol remains secure even under such an attack.\\n \\n \\n However, there are also cases where the honest players are quantum as well, even if the protocol uses classical communication.\\n For instance, this is the case when classical multiparty computation is used as a “subroutine” in quantum multiparty computation.\\n Furthermore, in the future, players in a protocol may employ quantum computing simply to improve efficiency of their local\\n computation, even if the communication is supposed to be classical. In such cases, it no longer seems clear that a quantum\\n adversary must be limited to only classical communication with the honest players. And so the natural question is: what happens\\n to the security if this limitation is dropped?\\n \\n \\n \\n In this talk, we survey some results from ongoing work that addresses this question, more specifically, we consider security\\n of secret sharing, zero-knowledge protocols and multiparty computation under this new paradigm. In all cases, both positive\\n and negative results can be shown. For instance, a classical threshold secret sharing scheme designed for threshold t is no longer secure in this model, but the same scheme is secure with threshold t/2.\\n \\n \\n \\n This is joint work with Jakob Funder, Jesper Buus Nielsen (Dept. of Computer Science, Aarhus University) and Louis Salvail\\n (Université de Montréal).\",\n \"Title: Quantum-Secure Coin-Flipping and Applications\\nYear: 2009\\n\\nAbstract: In this paper, we prove classical coin-flipping secure in the presence of quantum adversaries. The proof uses a recent result of Watrous [20] that allows quantum rewinding for protocols of a certain form. We then discuss two applications. First, the combination of coin-flipping with any non-interactive zero-knowledge protocol leads to an easy transformation from non-interactive zero-knowledge to interactive quantum zero-knowledge. Second, we discuss how our protocol can be applied to a recently proposed method for improving the security of quantum protocols [4], resulting in an implementation without set-up assumptions. Finally, we sketch how to achieve efficient simulation for an extended construction in the common-reference-string model.\",\n \"Title: Non-interactive zero-knowledge from homomorphic encryption\\nYear: 2006\\n\\nAbstract: We propose a method for compiling a class of Σ-protocols (3-move public-coin protocols) into non-interactive zero-knowledge arguments. The method is based on homomorphic encryption and does not use random oracles. It only requires that a private/public key pair is set up for the verifier. The method applies to all known discrete-log based Σ-protocols. As applications, we obtain non-interactive threshold RSA without random oracles, and non-interactive zero-knowledge for NP more efficiently than by previous methods.\",\n \"Title: Public-key encryption with non-interactive opening\\nYear: 2008\\n\\nAbstract: We formally define the primitive of public-key encryption with non-interactive opening (PKENO), where the receiver of a cipher-text C can, convincingly and without interaction, reveal what the result was of decrypting C, without compromising the scheme's security. This has numerous applications in cryptographic protocol design, e.g., when the receiver wants to demonstrate that some information he was sent privately was not correctly formed. We give a definition based on the UC framework as well as an equivalent game-based definition. The PKENO concept was informally introduced by Damgård and Thorbek who suggested that it could be implemented based on Identity-Based Encryption. In this paper, we give direct and optimized implementations, that work without having to keep state information, unlike what one obtains from directly using IBE.\",\n \"Title: Multiparty computation for dishonest majority: from passive to active security at low cost\\nYear: 2010\\n\\nAbstract: Multiparty computation protocols have been known for more than twenty years now, but due to their lack of efficiency their use is still limited in real-world applications: the goal of this paper is the design of efficient two and multi party computation protocols aimed to fill the gap between theory and practice. We propose a new protocol to securely evaluate reactive arithmetic circuits, that offers security against an active adversary in the universally composable security framework. Instead of the \\\"do-and-compile\\\" approach (where the parties use zero-knowledge proofs to show that they are following the protocol) our key ingredient is an efficient version of the \\\"cut-and-choose\\\" technique, that allow us to achieve active security for just a (small) constant amount of work more than for passive security.\",\n \"Title: An Integer Commitment Scheme based on Groups with Hidden Order.\\nYear: 2001\\n\\nAbstract: Abstract. We present a commitment,scheme allowing commitment,to arbitrary size integers, based on any Abelian group with certain properties, most importantly that it is hard for the committer to compute its order. Potential examples include RSA and class groups. We also give efficient zero-knowledge protocols for proving knowledge ofthe contents of a commitment,and for verifying multiplicative relations over the integers on committed values. This means that our scheme can support, for instance, the efficent interval proofs of Boudot[1]. The scheme can be seen as a modification and a generalization of an earlier scheme,of Fujisaki and Okamoto [5], and in particular our results show that we can use a much,larger class of RSA moduli than the safe prime products proposed in [5]. Also, we correct some mistakes in the proofs of [5] and give what appears to be the first multiplication protocol for a Fujisaki/Okamoto-like scheme with a complete proof of soundness.\",\n \"Title: Secure protocols with asymmetric trust\\nYear: 2007\\n\\nAbstract: In the standard general-adversary model for multi-party protocols, a global adversary structure is given, and every party must trust in this particular structure. We introduce a more general model, the asymmetric-trust model, wherein every party is allowed to trust in a different, personally customized adversary structure. We have two main contributions. First, we present non-trivial lower and upper bounds for broadcast, verifiable secret sharing, and general multi-party computation in different variations of this new model. The obtained bounds demonstrate that the new model is strictly more powerful than the standard general-adversary model. Second, we propose a framework for expressing and analyzing asymmetric trust in the usual simulation paradigm for defining security of protocols, and in particular show a general composition theorem for protocols with asymmetric trust.\",\n \"Title: Perfect Hiding and Perfect Binding Universally Composable Commitment Schemes with Constant Expansion Factor\\nYear: 2001\\n\\nAbstract: Canetti and Fischlin have recently proposed the security notion universal composability for commitment schemes and provided two examples. This new notion is very strong. It guarantees that security is maintained even when an unbounded number of copies of the scheme are running concurrently, also it guarantees non-malleability and security against adaptive adversaries. Both proposed schemes use 驴(k) bits to commit to one bit and can be based on the existence of trapdoor commitments and non-malleable encryption.We present new universally composable commitment (UCC) schemes based on extractable q one-way homomorphisms. These in turn exist based on the Paillier cryptosystem, the Okamoto-Uchiyama cryptosystem, or the DDH assumption. The schemes are efficient: to commit to k bits, they use a constant number of modular exponentiations and communicates O(k) bits. Furthermore the scheme can be instantiated in either perfectly hiding or perfectly binding versions. These are the first schemes to show that constant expansion factor, perfect hiding, and perfect binding can be obtained for universally composable commitments.We also show how the schemes can be applied to do efficient zero-knowledge proofs of knowledge that are universally composable.\",\n \"Title: Short Non-Interactive Cryptographic Proofs\\nYear: 2000\\n\\nAbstract: We show how to produce short proofs of theorems such that a distrusting Verifier can be convinced that the theorem is true yet obtains no information about the proof itself. We assume the theorem is represented by a boolean circuit, of size m gates, which is satisfiable if and only if the theorem holds. We use bit commitments of size k and bound the probability of false proofs going undetected by 2 r . We obtain non-interactive zero-knowledge proofs of size O(mk(log m + r)) bits. In the random...\",\n \"Title: Speeding up Prime Number Generation\\nYear: 1991\\n\\nAbstract: We present various ways of speeding up the standard methods for generating provable, resp. probable primes. For probable primes, the effect of using test division and 2 as a fixed base for the Rabin test is analysed, showing that a speedup of almost 50% can be achieved with the same confidence level, compared to the standard method. For Maurer's algorithm generating provable primes p, we show that a small extension of the algorithm will mean that only one prime factor of p–1 has to be generated, implying a gain in efficiency. Further savings can be obtained by combining with the Rabin test. Finally, we show how to combine the algorithms of Maurer and Gordon to make strong provable primes that satisfy additional security constraints.\",\n \"Title: Sequential Iteration of Interactive Arguments and an Efficient Zero-Knowledge Argument for NP\\nYear: 1998\\n\\nAbstract: We study interactive arguments, in particular their error probability under sequential iteration. This problem is more complex\\n than for interactive proofs, where the error trivially decreases exponentially in the number of iterations.\\n \\n In particular, we study the typical efficient case where the iterated protocol is based on a single instance of a computational\\n problem. This is not a special case of independent iterations of an entire protocol, and real exponential decrease of the\\n error cannot be expected. Nevertheless, for practical applications, one needs concrete relations between the complexity and\\n error probability of the underlying problem and the iterated protocol. We formalize and solve this problem using the theory\\n of proofs of knowledge. We also seem to present the first definition of arguments in a fully uniform model of complexity.\\n \\n \\n \\n We also prove that in non-uniform complexity, the error probability of independent iterations of an argument does decrease\\n exponentially — to our knowledge this is the first result about a strictly exponentially small error probability in a computational\\n cryptographic security property.\\n \\n \\n \\n To illustrate our first result, we present a very efficient zero-knowledge argument for circuit satisfiability, and thus for\\n any NP problem, based on any collision-intractable hash function.\",\n \"Title: On the necessary and sufficient assumptions for UC computation\\nYear: 2010\\n\\nAbstract: We study the necessary and sufficient assumptions for universally composable (UC) computation, both in terms of setup and computational assumptions. We look at the common reference string model, the uniform random string model and the key-registration authority model (KRA), and provide new results for all of them. Perhaps most interestingly we show that: For even the minimal meaningful KRA, where we only assume that the secret key is a value which is hard to compute from the public key, one can UC securely compute any poly-time functionality if there exists a passive secure oblivious-transfer protocol for the stand-alone model. Since a KRA where the secret keys can be computed from the public keys is useless, and some setup assumption is needed for UC secure computation, this establishes the best we could hope for the KRA model: any non-trivial KRA is sufficient for UC computation. We show that in the KRA model one-way functions are sufficient for UC commitment and UC zero-knowledge. These are the first examples of UC secure protocols for non-trivial tasks which do not assume the existence of public-key primitives. In particular, the protocols show that non-trivial UC computation is possible in Minicrypt.\",\n \"Title: Efficient threshold RSA signatures with general moduli and no extra assumptions\\nYear: 2005\\n\\nAbstract: We propose techniques that allow construction of robust threshold RSA signature schemes that can work without a trusted dealer using known key generation protocols and is as efficient as the best previous schemes. We do not need special conditions on the RSA modulus, extra complexity or set-up assumptions or random oracles. An “optimistic” variant of the scheme is even more efficient in case no faults occur. Some potential more general applications of our basic idea are also pointed out.\",\n \"Title: Universally Composable Symbolic Analysis for Two-Party Protocols based on Homomorphic Encryption.\\nYear: 2014\\n\\nAbstract: We consider a class of two-party function evaluation protocols in which the parties are allowed to use ideal functionalities as well as a set of powerful primitives, namely commitments, homomorphic encryption, and certain zero-knowledge proofs. With these it is possible to capture protocols for oblivious transfer, coin-flipping, and generation of multiplication-triples. We show how any protocol in our class can be compiled to a symbolic representation expressed as a process in an abstract process calculus, and prove a general computational soundness theorem implying that if the protocol realises a given ideal functionality in the symbolic setting, then the original version also realises the ideal functionality in the standard computational UC setting. In other words, the theorem allows us to transfer a proof in the abstract symbolic setting to a proof in the standard UC model. Finally, we have verified that the symbolic interpretation is simple enough in a number of cases for the symbolic proof to be partly automated using the ProVerif tool.\",\n \"Title: Semi-homomorphic encryption and multiparty computation\\nYear: 2011\\n\\nAbstract: An additively-homomorphic encryption scheme enables us to compute linear functions of an encrypted input by manipulating only the ciphertexts. We define the relaxed notion of a semi-homomorphic encryption scheme, where the plaintext can be recovered as long as the computed function does not increase the size of the input \\\"too much\\\". We show that a number of existing cryptosystems are captured by our relaxed notion. In particular, we give examples of semi-homomorphic encryption schemes based on lattices, subset sum and factoring. We then demonstrate how semi-homomorphic encryption schemes allow us to construct an efficient multiparty computation protocol for arithmetic circuits, UC-secure against a dishonest majority. The protocol consists of a preprocessing phase and an online phase. Neither the inputs nor the function to be computed have to be known during preprocessing. Moreover, the online phase is extremely efficient as it requires no cryptographic operations: the parties only need to exchange additive shares and verify information theoretic MACs. Our contribution is therefore twofold: from a theoretical point of view, we can base multiparty computation on a variety of different assumptions, while on the practical side we offer a protocol with better efficiency than any previous solution.\",\n \"Title: On The Orthogonal Vector Problem And The Feasibility Of Unconditionally Secure Leakage-Resilient Computation\\nYear: 2014\\n\\nAbstract: We consider unconditionally secure leakage resilient two-party computation. Security means that the leakage obtained by an adversary can be simulated using a similar amount of leakage from the private inputs or outputs. A related problem is known as circuit compilation, where there is only one device doing a computation on public input and output. Here the goal is to ensure that the adversary learns only the input/output behaviour of the computation, even given leakage from the internal state of the device. We study these problems in an enhanced version of the \\\"only computation leaks\\\" model, where the adversary is additionally allowed a bounded amount of global leakage from the state of the entity under attack. In this model, we show the first unconditionally secure leakage resilient two-party computation protocol. The protocol assumes access to correlated randomness in the form of a functionality f(ORT) that outputs pairs of orthogonal vectors (u, v) over some finite field, where the adversary can leak independently from u and from v. We also construct a general circuit compiler secure in the same leakage model. Our constructions work, even if the adversary is allowed to corrupt a constant fraction of the calls to f(ORT) and decide which vectors should be output. On the negative side, we show that unconditionally secure two-party computation and circuit compilation are in general impossible in the plain version of our model. It follows that even a somewhat unreliable version of f(ORT) cannot be implemented with unconditional security in the plain leakage model, using classical communication. However, we show that an implementation using quantum communication does exist. In particular, we propose a simple \\\"prepare-and-measure\\\" type protocol which we show secure using a new result on sampling from a quantum population. Although the protocol may produce a small number of incorrect pairs, this is sufficient for leakage resilient computation by our other results. To the best of our knowledge, this is the first time a quantum protocol is used constructively for leakage resilience.Note that the full version of this paper is available at [6].\",\n \"Title: A quantum cipher with near optimal key-recycling\\nYear: 2005\\n\\nAbstract: Assuming an insecure quantum channel and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.\",\n \"Title: Constant-Overhead secure computation of boolean circuits using preprocessing\\nYear: 2013\\n\\nAbstract: We present a protocol for securely computing a Boolean circuit C in presence of a dishonest and malicious majority. The protocol is unconditionally secure, assuming a preprocessing functionality that is not given the inputs. For a large number of players the work for each player is the same as computing the circuit in the clear, up to a constant factor. Our protocol is the first to obtain these properties for Boolean circuits. On the technical side, we develop new homomorphic authentication schemes based on asymptotically good codes with an additional multiplication property. We also show a new algorithm for verifying the product of Boolean matrices in quadratic time with exponentially small error probability, where previous methods only achieved constant error.\",\n \"Title: Concurrent Zero-Knowledge is Easy in Practice.\\nYear: 1999\\n\\nAbstract: We show that if any one-way function exists, then 3-round concurrent zero-knowledge arguments for all NP problems can be built in a model where a short auxiliary string with a prescribed distribution is available to the players. We also show that all known efficient identification schemes using specialized assumptions can be modified to work in this model with no essential loss of efficiency. We argue that the assumptions of the model will be satisfied in most practical scenarios where public...\",\n \"Title: DAKOTA: hashing from a combination of modular arithmetic and symmetric cryptography\\nYear: 2008\\n\\nAbstract: In this paper a cryptographic hash function is proposed, where collision resistance is based upon an assumption that involves squaring modulo an RSA modulus in combination with a one-way function that does not compress its input, and may therefore be constructed from standard techniques and assumptions. We are not able to reduce collision finding to factoring, but on the other hand, our hash function is more efficient than any known construction that makes use of modular squaring.\",\n \"Title: General secure multi-party computation from any linear secret-sharing scheme\\nYear: 2000\\n\\nAbstract: We show that verifiable secret sharing (VSS) and secure multi-party computation (MPC) among a set of n players can efficiently be based on any linear secret sharing scheme (LSSS) for the players, provided that the access structure of the LSSS allows MPC or VSS at all. Because an LSSS neither guarantees reconstructability when some shares are false, nor verifiability of a shared value, nor allows for the multiplication of shared values, an LSSS is an apparently much weaker primitive than VSS or MPC. Our approach to secure MPC is generic and applies to both the information-theoretic and the cryptographic setting. The construction is based on 1) a formalization of the special multiplicative property of an LSSS that is needed to perform a multiplication on shared values, 2) an efficient generic construction to obtain from any LSSS a multiplicative LSSS for the same access structure, and 3) an efficient generic construction to build verifiability into every LSSS (always assuming that the adversary structure allows for MPC or VSS at all). The protocols are efficient. In contrast to all previous information-theoretically secure protocols, the field size is not restricted (e.g, to be greater than n). Moreover, we exhibit adversary structures for which our protocols are polynomial in n while all previous approaches to MPC for non-threshold adversaries provably have super-polynomial complexity.\",\n \"Title: Zero-Knowledge Proofs for Finite Field Arithmetic; or: Can Zero-Knowledge be for Free?\\nYear: 1998\\n\\nAbstract: We present zero-knowledge proofs and arguments for arithmetic circuits over finiteprime fields, namely given a circuit, show in zero-knowledge that inputs can beselected leading to a given output. For a field GF (q), where q is an n-bit prime, acircuit of size O(n), and error probability 2, our protocols require communication ofO(n) bits. This is the same worst-cast complexity as the trivial (non zero-knowledge)interactive proof where the prover just reveals the input values....\",\n \"Title: Linear Zero-Knowledge - A note on Efficient Zero-Knowledge Proofs and Arguments.\\nYear: 1996\\n\\nAbstract: We present a 4-move zero-knowledge proof system[21] for any NP language L, which allows showing thatx 2 L with error probability less than 2\\\\Gammakusing communicationcorresponding to O(jxjc)+O(k) bit commitments,where c is a constant depending only on L. Wealso present a 4-move perfect zero knowledge interactiveargument for any NP-language L. On input x 2 L,the communication complexity is O(jxjc) \\\\Delta max(k; l) bits,where l is the security parameter for the prover1....\",\n \"Title: Atomic Secure Multi-party Multiplication with Low Communication\\nYear: 2007\\n\\nAbstract: We consider the standard secure multi-party multiplication protocol due to M. Rabin. This protocol is based on Shamir's secret sharing scheme and it can be viewed as a practical variation on one of the central techniques in the foundational results of Ben-Or, Goldwasser, and Wigderson and Chaum, Crépeau, and Damgaard on secure multi-party computation. Rabin's idea is a key ingredient to virtually all practical protocols in threshold cryptography.Given a passive t-adversary in the secure channels model with synchronous communication, for example, secure multiplication of two secret-shared elements from a finite field Kbased on this idea uses one communication round and has the network exchange O(n2) field elements, if t= 驴(n) and tn/2 and if nis the number of players. This is because each of O(n) players must perform Shamir secret sharing as part of the protocol. This paper demonstrates that under a few restrictions much more efficient protocols are possible; even at the level of a single multiplication.We demonstrate a twist on Rabin's idea that enables one-round secure multiplication with just O(n)bandwidthin certain settings, thus reducing it from quadratic to linear. The ideas involved can additionally be employed in the evaluation of arithmetic circuits, where under appropriate circumstances similar efficiency gains can be obtained.\",\n \"Title: A generalization of Paillier’s public-key system with applications to electronic voting\\nYear: 2010\\n\\nAbstract: We propose a generalization of Paillier’s probabilistic public-key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without losing the homomorphic property. We show that the generalization is as secure as Paillier’s original system and propose several ways to optimize implementations of both the generalized and the original scheme. We construct a threshold variant of the generalized scheme as well as zero-knowledge protocols to show that a given ciphertext encrypts one of a set of given plaintexts, and protocols to verify multiplicative relations on plaintexts. We then show how these building blocks can be used for applying the scheme to efficient electronic voting. This reduces dramatically the work needed to compute the final result of an election, compared to the previously best known schemes. We show how the basic scheme for a yes/no vote can be easily adapted to casting a vote for up to t out of L candidates. The same basic building blocks can also be adapted to provide receipt-free elections, under appropriate physical assumptions. The scheme for 1 out of L elections can be optimized such that for a certain range of the other parameter values, the ballot size is logarithmic in L.\",\n \"Title: Secure computation, i/o-efficient algorithms and distributed signatures\\nYear: 2012\\n\\nAbstract: We consider a setting where a set of n players use a set of m servers to store a large, private data set. Later the players decide on functions they want to compute on the data without the servers needing to know which computation is done, while the computation should be secure against a malicious adversary corrupting a constant fraction of the players and servers. Using packed secret sharing, the data can be stored in a compact way but will only be accessible in a block-wise fashion. We explore the possibility of using I/O-efficient algorithms to nevertheless compute on the data as efficiently as if random access was possible. We show that for sorting, priority queues and data mining, this can indeed be done. We show actively secure protocols of complexity within a constant factor of the passively secure solution. As a technical contribution towards this goal, we develop techniques for generating values of form r, gr for random secret-shared r∈ℤq and gr in a group of order q. This costs a constant number of exponentiation per player per value generated, even if less than n/3 players are malicious. This can be used for efficient distributed computing of Schnorr signatures. We further develop the technique so we can sign secret data in a distributed fashion at essentially the same cost.\",\n \"Title: Towards Practical Public Key Systems Secure Against Chosen Ciphertext Attacks\\nYear: 1991\\n\\nAbstract: We present two efficient constructions aimed at making public key systems secure against chosen ciphertext attacks. The first one applies to any deterministic public key system and modifies it into a system that is provably as hard to break under a passive attack as the original one, but has the potential of making a chosen ciphertext attack useless to an enemy. The second construction applies to the El Gamal/Diffie-Hellman public key system. Again, the modified system is provably as hard to break under a passive attack as the original one, and under an additional cryptographic assumption, a chosen ciphertext attack is provably useless to an enemy. We also point out a connection between such public-key systems and efficient identification schemes.\",\n \"Title: Improving the Security of Quantum Protocols via Commit-and-Open\\nYear: 2009\\n\\nAbstract: We consider two-party quantum protocols starting with a transmission of some random BB84 qubits followed by classical messages. We show a general \\\"compiler\\\" improving the security of such protocols: if the original protocol is secure against an \\\"almost honest\\\" adversary, then the compiled protocol is secure against an arbitrary computationally bounded (quantum) adversary. The compilation preserves the number of qubits sent and the number of rounds up to a constant factor. The compiler also preserves security in the bounded-quantum-storage model (BQSM), so if the original protocol was BQSM-secure, the compiled protocol can only be broken by an adversary who has large quantum memory and large computing power. This is in contrast to known BQSM-secure protocols, where security breaks down completely if the adversary has larger quantum memory than expected. We show how our technique can be applied to quantum identification and oblivious transfer protocols.\",\n \"Title: Zero-Knowledge Proofs and String Commitments Withstanding Quantum Attacks\\nYear: 2004\\n\\nAbstract: The concept of zero-knowledge (ZK) has become of fundamental importance in cryptography. However, in a setting where entities are modeled by quantum computers, classical arguments for proving ZK fail to hold since, in the quantum setting, the concept of rewinding is not generally applicable. Moreover, known classical techniques that avoid rewinding have various shortcomings in the quantum setting. We propose new techniques for building quantum zero-knowledge (QZK) protocols, which remain secure even under (active) quantum attacks. We obtain computational QZK proofs and perfect QZK arguments for any NP language in the common reference string model. This is based on a general method converting an important class of classical honest-verifier ZK (HVZK) proofs into QZK proofs. This leads to quite practical protocols if the underlying HVZK proof is efficient. These are the first proof protocols enjoying these properties, in particular the first to achieve perfect QZK. As part of our construction, we propose a general framework for building unconditionally hiding (trapdoor) string commitment schemes, secure against quantum attacks, as well as concrete instantiations based on specific (believed to be) hard problems. This is of independent interest, as these are the first unconditionally hiding string commitment schemes withstanding quantum attacks. Finally, we give a partial answer to the question whether QZK is possible in the plain model. We propose a new notion of QZK, non-oblivious verifier QZK, which is strictly stronger than honest-verifier QZK but weaker than full QZK, and we show that this notion can be achieved by means of efficient (quantum) protocols.\",\n \"Title: How to re-use a one-time pad safely and almost optimally even if P = NP\\nYear: 2014\\n\\nAbstract: uming an insecure quantum channel, a quantum computer, and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.\",\n \"Title: The Chaining Lemma And Its Application\\nYear: 2014\\n\\nAbstract: We present a new information-theoretic result which we call the Chaining Lemma. It considers a so-called \\\"chain\\\" of random variables, defined by a source distribution X-(0) with high min-entropy and a number (say, t in total) of arbitrary functions (T-1,...,T-t) which are applied in succession to that source to generate the chain X-(0) (sic) X-(1) (sic) X-(2)...(sic) X-(t). Intuitively, the Chaining Lemma guarantees that, if the chain is not too long, then either (i) the entire chain is \\\"highly random\\\", in that every variable has high min-entropy; or (ii) it is possible to find a point j (1 <= j <= t) in the chain such that, conditioned on the end of the chain i.e. X-(j) (sic) X(j+1)...(sic) X-(t), the preceding part X-(0) (sic) X-(1)...(sic) X-(j) remains highly random. We think this is an interesting information-theoretic result which is intuitive but nevertheless requires rigorous case-analysis to prove.We believe that the above lemma will find applications in cryptography. We give an example of this, namely we show an application of the lemma to protect essentially any cryptographic scheme against memorytampering attacks. We allow several tampering requests, the tampering functions can be arbitrary, however, they must be chosen from a bounded size set of functions that is fixed a priori.\",\n \"Title: Compact VSS and Efficient Homomorphic UC Commitments.\\nYear: 2014\\n\\nAbstract: We present a new compact verifiable secret sharing scheme, based on this we present the first construction of a homomorphic UC commitment scheme that requires only cheap symmetric cryptography, except for a small number of seed OTs. To commit to a k-bit string, the amortized communication cost is O(k) bits. Assuming a sufficiently efficient pseudorandom generator, the computational complexity is O(k) for the verifier and O(k(1+is an element of)) for the committer (where is an element of < 1 is a constant). In an alternative variant of the construction, all complexities are O(k . polylog(k)). Our commitment scheme extends to vectors over any finite field and is additively homomorphic. By sending one extra message, the prover can allow the verifier to also check multiplicative relations on committed strings, as well as verifying that committed vectors a, b satisfy a = phi(b) for a linear function phi. These properties allow us to non-interactively implement any one-sided functionality where only one party has input (this includes UC secure zero-knowledge proofs of knowledge). We also present a perfectly secure implementation of any multiparty functionality, based directly on our VSS. The communication required is proportional to a circuit implementing the functionality, up to a logarithmic factor. For a large natural class of circuits the overhead is even constant. We also improve earlier results by Ranellucci et al. on the amount of correlated randomness required for string commitments with individual opening of bits.\",\n \"Title: Adaptive Versus Static Security In The Uc Model\\nYear: 2014\\n\\nAbstract: We show that for certain class of unconditionally secure protocols and target functionalities, static security implies adaptive security in the UC model. Similar results were previously only known for models with weaker security and/or composition guarantees. The result is, for instance, applicable to a wide range of protocols based on secret sharing. It \\\"explains\\\" why an often used proof technique for such protocols works, namely where the simulator runs in its head a copy of the honest players using dummy inputs and generates a protocol execution by letting the dummy players interact with the adversary. When a new player P-i is corrupted, the simulator adjusts the state of its dummy copy of P-i to be consistent with the real inputs and outputs of P-i and gives the state to the adversary. Our result gives a characterization of the cases where this idea will work to prove adaptive security. As a special case, we use our framework to give the first proof of adaptive security of the seminal BGW protocol in the UC framework.\",\n \"Title: On the Communication required for Unconditionally Secure Multiplication.\\nYear: 2016\\n\\nAbstract: Many information-theoretic secure protocols are known for general secure multi-party computation, in the honest majority setting, and in the dishonest majority setting with preprocessing. All known protocols that are efficient in the circuit size of the evaluated function follow the same \\\\\\\"gate-by-gate\\\\\\\" design pattern: we work through an arithmetic boolean circuit on secret-shared inputs, such that after we process a gate, the output of the gate is represented as a random secret sharing among the players. This approach usually allows non-interactive processing of addition gates but requires communication for every multiplication gate. Thus, while information-theoretic secure protocols are very efficient in terms of computational work, they seem to require more communication and more rounds than computationally secure protocols. Whether this is inherent is an open and probably very hard problem. However, in this work we show that it is indeed inherent for protocols that follow the \\\\\\\"gate-by-gate\\\\\\\" design pattern. We present the following results:In the honest majority setting, as well as for dishonest majority with preprocessing, any gate-by-gate protocol must communicate $$\\\\\\\\varOmega n$$ bits for every multiplication gate, where n is the number of players.In the honest majority setting, we show that one cannot obtain a bound that also grows with the field size. Moreover, for a constant number of players, amortizing over several multiplication gates does not allow us to save on the computational work, and --- in a restricted setting --- we show that this also holds for communication. All our lower bounds are met up﾿to a constant factor by known protocols that follow the typical gate-by-gate paradigm. Our results imply that a fundamentally new approach must be found in order to improve the communication complexity of known protocols, such as BGW, GMW, SPDZ etc.\",\n \"Title: Rate-1, Linear Time and Additively Homomorphic UC Commitments.\\nYear: 2016\\n\\nAbstract: We construct the first UC commitment scheme for binary strings with the optimal properties of rate approaching 1 and linear time complexity in the amortised sense, using a small number of seed OTs. On top of this, the scheme is additively homomorphic, which allows for applications to maliciously secure 2-party computation. As tools for obtaining this, we make three contributions of independent interest: we construct the first binary linear time encodable codes with non-trivial distance and rate approaching 1, we construct the first almost universal hash function with small seed that can be computed in linear time, and we introduce a new primitive called interactive proximity testing that can be used to verify whether a string is close to a given linear code.\",\n \"Title: Access Control Encryption: Enforcing Information Flow with Cryptography.\\nYear: 2016\\n\\nAbstract: We initiate the study of Access Control Encryption ACE, a novel cryptographic primitive that allows fine-grained access control, by giving different rights to different users not only in terms of which messages they are allowed to receive, but also which messages they are allowed to send. Classical examples of security policies for information flow are the well known Bell-Lapadula﾿[BL73] or Biba﾿[Bib75] model: in a nutshell, the Bell-Lapadula model assigns roles to every user in the system e.g., public, secret and top-secret. A users' role specifies which messages the user is allowed to receive i.e., the no read-up rule, meaning that users with public clearance should not be able to read messages marked as secret or top-secret but also which messages the user is allowed to send i.e., the no write-down rule, meaning that a malicious user with top-secret clearance should not be able to write messages marked as secret or public. To the best of our knowledge, no existing cryptographic primitive allows for even this simple form of access control, since no existing cryptographic primitive enforces any restriction on what kind of messages one should be able to encrypt. Our contributions are:Introducing and formally defining access control encryption ACE;A construction of ACE with complexity linear in the number of the roles based on classic number theoretic assumptions DDH, Paillier;A construction of ACE with complexity polylogarithmic in the number of roles based on recent results on cryptographic obfuscation;\",\n \"Title: Confidential Benchmarking based on Multiparty Computation.\\nYear: 2016\\n\\nAbstract: We report on the design and implementation of a system that uses multiparty computation to enable banks to benchmark their customers' confidential performance data against a large representative set of confidential performance data from a consultancy house. The system ensures that both the banks' and the consultancy house's data stays confidential, the banks as clients learn nothing but the computed benchmarking score. In the concrete business application, the developed prototype helps Danish banks to find the most efficient customers among a large and challenging group of agricultural customers with too much debt. We propose a model based on linear programming for doing the benchmarking and implement it using the SPDZ protocol by Damgard et al., which we modify using a new idea that allows clients to supply data and get output without having to participate in the preprocessing phase and without keeping state during the computation. We ran the system with two servers doing the secure computation using a database with information on about 2500 users. Answers arrived in about 25 s.\",\n \"Title: Fast Oblivious AES\\\\\\\\A dedicated application of the MiniMac protocol.\\nYear: 2015\\n\\nAbstract: We present actively secure multi-party computation of the Advanced Encryption Standard AES. To the best of our knowledge it is the fastest of its kind to date. We start from an efficient actively secure evaluation of general binary circuits that was implemented by the authors of [DLT14]. They presented an optimized implementation of the so-called MiniMac protocol [DZ13] that runs in the pre-processing model, and applied this to a binary AES circuit. In this paper we describe how to dedicate the pre-processing to the structure of AES, which improves significantly the throughput and latency of previous actively secure implementations. We get a latency of about 6 ms and amortised time about 0.4 ms per AES block, which seems completely adequate for practical applications such as verification of 1-time passwords.\",\n \"Title: Better Preprocessing for Secure Multiparty Computation.\\nYear: 2016\\n\\nAbstract: We present techniques and protocols for the preprocessing of secure multiparty computation (MPC), focusing on the so-called SPDZ MPC scheme [14] and its derivatives [1,11,13]. These MPC schemes consist of a so-called preprocessing or offline phase where correlated randomness is generated that is independent of the inputs and the evaluated function, and an online phase where such correlated randomness is consumed to securely and efficiently evaluate circuits. In the recent years, it has been shown that such protocols (such as [5,17,18]) turn out to be very efficient in practice. While much research has been conducted towards optimizing the online phase of the MPC protocols, there seems to have been less focus on the offline phase of such protocols (except for [11]). With this work, we want to close this gap and give a toolbox of techniques that aim at optimizing the preprocessing. We support both instantiations over small fields and large rings using somewhat homomorphic encryption and the Paillier cryptosystem [19], respectively. In the case of small fields, we show how the preprocessing overhead can basically be made independent of the field characteristic. In the case of large rings, we present a protocol based on the Paillier cryptosystem which has a lower message complexity than previous protocols and employs more efficient zero-knowledge proofs that, to the best of our knowledge, were not presented in previous work.\",\n \"Title: Unconditionally Secure Computation with Reduced Interaction.\\nYear: 2015\\n\\nAbstract: We study the question of how much interaction is needed for unconditionally secure multiparty computation. We first consider the number of messages that need to be sent to compute a Boolean function with semi-honest security, where all n parties learn the result. We consider two classes of functions called t-difficult and t-very difficult functions, where t refers to the number of corrupted players. For instance, the AND of an input bit from each player is t-very difficult while the XOR is t-difficult but not t-very difficult. We show lower bounds on the message complexity of both types of functions, considering two notions of message complexity called conservative and liberal, where conservative is the more standard one. In all cases the bounds are $$\\\\\\\\varOmega nt$$ Ωnt. We also show almost matching upper bounds for $$t=1$$ t=1 and functions in a rich class $$PSM_\\\\\\\\mathsf{eff}$$ PSMeff including non-deterministic log-space, as well as a stronger upper bound for the XOR function. In particular, we find that the conservative message complexity of 1-very difficult functions in $$PSM_\\\\\\\\mathsf{eff}$$ PSMeff is 2n, while the conservative message complexity for XOR and $$t=1$$ t=1 is $$2n-1$$ 2n-1. Next, we consider round complexity. It is a long-standing open problem to determine whether all efficiently computable functions can also be efficiently computed in constant-round with unconditional security. Motivated by this, we consider the question of whether we can compute any function securely, while minimizing the interaction of some of the players? And if so, how many players can this apply to? Note that we still want the standard security guarantees correctness, privacy, termination and we consider the standard communication model with secure point-to-point channels. We answer the questions as follows: for passive security, with $$n=2t+1$$ n=2t+1 players and t corruptions, up﾿to t players can have minimal interaction, i.e., they send 1 message in the first round to each of the $$t+1$$ t+1 remaining players and receive one message from each of them in the last round. Using our result on message complexity, we show that this is unconditionally optimal. For malicious security with $$n=3t+1$$ n=3t+1 players and t corruptions, up﾿to t players can have minimal interaction, and we show that this is also optimal.\",\n \"Title: Adaptively Secure Multi-Party Computation from LWE (via Equivocal FHE).\\nYear: 2016\\n\\nAbstract: Adaptively secure Multi-Party Computation MPC is an essential and fundamental notion in cryptography. In this work, we construct Universally Composable UC MPC protocols that are adaptively secure against all-but-one corruptions based on LWE. Our protocols have a constant number of rounds and communication complexity dependant only on the length of the inputs and outputs it is independent of the circuit size. Such protocols were only known assuming an honest majority. Protocols in the dishonest majority setting, such as the work of Ishai et al. CRYPTO 2008, require communication complexity proportional to the circuit size. In addition, constant-round adaptively secure protocols assuming dishonest majority are known to be impossible in the stand-alone setting with black-box proofs of security in the plain model. Here, we solve the problem in the UC setting using a set-up assumption which was shown necessary in order to achieve dishonest majority. The problem of constructing adaptively secure constant-round MPC protocols against arbitrary corruptions is considered a notorious hard problem. A recent line of works based on indistinguishability obfuscation construct such protocols with near-optimal number of rounds against arbitrary corruptions. However, based on standard assumptions, adaptively secure protocols secure against even just all-but-one corruptions with near-optimal number of rounds are not known. However, in this work we provide a three-round solution based only on LWE and NIZK secure against all-but-one corruptions. In addition, Asharov et al. EUROCRYPT 2012 and more recently Mukherjee and Wichs ePrint 2015 presented constant-round protocols based on LWE which are secure only in the presence of static adversaries. Assuming NIZK and LWE their static protocols run in two rounds where the latter one is only based on a common random string. Assuming adaptively secure UC NIZK, proposed by Groth et al. ACM 2012, and LWE as mentioned above our adaptive protocols run in three rounds. Our protocols are constructed based on a special type of cryptosystem we call equivocal FHE from LWE. We also build adaptively secure UC commitments and UC zero-knowledge proofs of knowledge from LWE. Moreover, in the decryption phase using an AMD code mechanism we avoid the use of ZK and achieve communication complexity that does not scale with the decryption circuit.\",\n \"Title: Entangled Encodings and Data Entanglement\\nYear: 2015\\n\\nAbstract: We introduce a new cryptographic tool that we dub entangled encoding scheme. An entangled encoding allows a set of users to encode their files into a single digital \\\\\\\"clew\\\\\\\" such that the following two properties are satisfied. (1) Privacy: The resulting encoding reveals no information about the files contained inside the clew; (2) All-or-nothing integrity (AONI): It is impossible to modify or delete any significant part of the encoding without affecting all files contained in the clew. We provide a concrete instantiation of an entangled encoding scheme with unconditional security, based on polynomial interpolation over a finite field. Finally, we show an appealing application of entangled encodings to the setting of secure cloud storage, where a set of users store their files at a potentially malicious cloud provider and want to ensure that their data remain safe and unblemished.\",\n \"Title: How to prove knowledge of small secrets.\\nYear: 2016\\n\\nAbstract: We propose a new zero-knowledge protocol applicable to additively homomorphic functions that map integer vectors to an Abelian group. The protocol demonstrates knowledge of a short preimage and achieves amortised efficiency comparable to the approach of Cramer and Damgård from Crypto 2010, but gives a much tighter bound on what we can extract from a dishonest prover. Towards achieving this result, we develop an analysis for bins-and-balls games that might be of independent interest. We also provide a general analysis of rewinding of a cut-and-choose protocol as well as a method to use Lyubachevsky's rejection sampling technique efficiently in an interactive protocol when many proofs are given simultaneously. Our new protocol yields improved proofs of plaintext knowledge for Ring-LWE-based cryptosystems, where such general techniques were not known before. Moreover, they can be extended to prove preimages of homomorphic hash functions as well.\",\n \"Title: Amortized Complexity of Zero-Knowledge Proofs Revisited: Achieving Linear Soundness Slack.\\nYear: 2017\\n\\nAbstract: We propose a new zero-knowledge protocol for proving knowledge of short preimages under additively homomorphic functions that map integer vectors to an Abelian group. The protocol achieves amortized efficiency in that it only needs to send O(n) function values to prove knowledge of n preimages. Furthermore we significantly improve previous bounds on how short a secret we can extract from a dishonest prover, namely our bound is a factor O(k) larger than the size of secret used by the honest prover, where k is the statistical security parameter. In the best previous result, the factor was O(k(log k) n). Our protocol can be applied to give proofs of knowledge for plaintexts in (Ring-) LWE-based cryptosystems, knowledge of preimages of homomorphic hash functions as well as knowledge of committed values in some integer commitment schemes.\",\n \"Title: Resource-efficient OT combiners with active security.\\nYear: 2017\\n\\nAbstract: An OT-combiner takes n candidate implementations of the oblivious transfer (OT) functionality, some of which may be faulty, and produces a secure instance of oblivious transfer as long as a large enough number of the candidates are secure. We see an OT-combiner as a 2-party protocol that can make several black-box calls to each of the n OT candidates, and we want to protect against an adversary that can corrupt one of the parties and a certain number of the OT candidates, obtaining their inputs and (in the active case) full control of their outputs.\",\n \"Title: Secure Arithmetic Computation with Constant Computational Overhead.\\nYear: 2017\\n\\nAbstract: We study the complexity of securely evaluating an arithmetic circuit over a finite field F in the setting of secure two-party computation with semi-honest adversaries. In all existing protocols, the number of arithmetic operations per multiplication gate grows either linearly with log vertical bar F vertical bar or polylogarithmically with the security parameter. We present the first protocol that only makes a constant (amortized) number of field operations per gate. The protocol uses the underlying field F as a black box, and its security is based on arithmetic analogues of well-studied cryptographic assumptions. Our protocol is particularly appealing in the special case of securely evaluating a \\\"vector-OLE\\\" function of the form ax + b, where x is an element of F is the input of one party and a, b is an element of F-w are the inputs of the other party. In this case, which is motivated by natural applications, our protocol can achieve an asymptotic rate of 1/3 (i.e., the communication is dominated by sending roughly 3w elements of F). Our implementation of this protocol suggests that it outperforms competing approaches even for relatively small fields F and over fast networks. Our technical approach employs two new ingredients that may be of independent interest. First, we present a general way to combine any linear code that has a fast encoder and a cryptographic (\\\"LPN-style\\\") pseudorandomness property with another linear code that supports fast encoding and erasure-decoding, obtaining a code that inherits both the pseudorandomness feature of the former code and the efficiency features of the latter code. Second, we employ local arithmetic pseudo-random generators, proposing arithmetic generalizations of boolean candidates that resist all known attacks.\",\n \"Title: The TinyTable Protocol for 2-Party Secure Computation, or: Gate-Scrambling Revisited.\\nYear: 2017\\n\\nAbstract: We propose a new protocol, nicknamed TinyTable, for maliciously secure 2-party computation in the preprocessing model. One version of the protocol is useful in practice and allows, for instance, secure AES encryption with latency about 1ms and amortized time about 0.5 mu s per AES block on a fast cloud set-up. Another version is interesting from a theoretical point of view: we achieve a maliciously and unconditionally secure 2-party protocol in the preprocessing model for computing a Boolean circuit, where both the communication complexity and preprocessed data size needed is O(s) where s is the circuit size, while the computational complexity is O(k(epsilon)s) where k is the statistical security parameter and epsilon < 1 is a constant. For general circuits with no assumption on their structure, this is the best asymptotic performance achieved so far in this model.\",\n \"Title: Yet Another Compiler for Active Security or: Efficient MPC Over Arbitrary Rings.\\nYear: 2018\\n\\nAbstract: We present a very simple yet very powerful idea for turning any passively secure MPC protocol into an actively secure one, at the price of reducing the threshold of tolerated corruptions. Our compiler leads to a very efficient MPC protocols for the important case of secure evaluation of arithmetic circuits over arbitrary rings e.g., the natural case of Z(2l)) for a small number of parties. We show this by giving a concrete protocol in the preprocessing model for the popular setting with three parties and one corruption. This is the first protocol for secure computation over rings that achieves active security with constant overhead.\",\n \"Title: Continuous Nmc Secure Against Permutations And Overwrites, With Applications To Cca Secure Commitments\\nYear: 2018\\n\\nAbstract: Non-Malleable Codes (NMC) were introduced by Dziembowski, Pietrzak and Wichs in ICS 2010 as a relaxation of error correcting codes and error detecting codes. Faust, Mukherjee, Nielsen, and Venturi in TCC 2014 introduced an even stronger notion of non-malleable codes called continuous non-malleable codes where security is achieved against continuous tampering of a single codeword without re-encoding.We construct information theoretically secure CNMC resilient to bit permutations and overwrites, this is the first Continuous NMC constructed outside of the split-state model.In this work we also study relations between the CNMC and parallel CCA commitments. We show that the CNMC can be used to bootstrap a Self-destruct parallel CCA bit commitment to a Self-destruct parallel CCA string commitment, where Self-destruct parallel CCA is a weak form of parallel CCA security. Then we can get rid of the Self-destruct limitation obtaining a parallel CCA commitment, requiring only one-way functions.\",\n \"Title: SPD \\\\mathbb Z_2^k : Efficient MPC mod 2^k for Dishonest Majority.\\nYear: 2018\\n\\nAbstract: Most multi-party computation protocols allow secure computation of arithmetic circuits over a finite field, such as the integers modulo a prime. In the more natural setting of integer computations modulo (2^{k}), which are useful for simplifying implementations and applications, no solutions with active security are known unless the majority of the participants are honest.\",\n \"Title: More Efficient Commitments from Structured Lattice Assumptions.\\nYear: 2018\\n\\nAbstract: We present a practical construction of an additively homomorphic commitment scheme based on structured lattice assumptions, together with a zero-knowledge proof of opening knowledge. Our scheme is a design improvement over the previous work of Benhamouda et al. in that it is not restricted to being statistically binding. While it is possible to instantiate our scheme to be statistically binding or statistically hiding, it is most efficient when both hiding and binding properties are only computational. This results in approximately a factor of 4 reduction in the size of the proof and a factor of 6 reduction in the size of the commitment over the aforementioned scheme.\",\n \"Title: Proofs of Replicated Storage Without Timing Assumptions\\nYear: 2018\\n\\nAbstract: In this paper we provide a formal treatment of proof of replicated storage, a novel cryptographic primitive recently proposed in the context of a novel cryptocurrency, namely Filecoin. In a nutshell, proofs of replicated storage is a solution to the following problem: A user stores a file m on n different servers to ensure that the file will be available even if some of the servers fail. Using proof of retrievability, the user could check that every server is indeed storing the file. However, what if the servers collude and, in order to save on resources, decide to only store one copy of the file? A proof of replicated storage guarantees that, unless the (potentially colluding) servers are indeed reserving the space necessary to store n copies of the file, the user will not accept the proofs. While some candidate proofs of replicated storage have already been proposed, their soundness relies on timing assumptions i.e., the user must reject the proof if the prover does not reply within a certain time-bound. In this paper we provide the first construction of a proof of replication which does not rely on any timing assumptions.\",\n \"Title: A \\\"proof-reading\\\" of some issues in cryptography\\nYear: 2007\\n\\nAbstract: In this paper, we identify some issues in the interplay between practice and theory in cryptography, issues that have repeatedly appeared in different incarnations over the years. These issues are related to fundamental concepts in the field, e.g., to what extent we can prove that a system is secure and what theoretic results on security mean for practical applications. We argue that several such issues are often overlooked or misunderstood, and that it may be very productive if both theoreticians and practitioners think more consciously about these issues and act accordingly.\",\n \"Title: Isolated proofs of knowledge and isolated zero knowledge\\nYear: 2008\\n\\nAbstract: We consider proof of knowledge protocols where the cheating prover may communicate with some external adversarial environment during the run of the proof. Without additional setup assumptions, no witness hiding protocol can securely ensure that the prover knows a witness in this scenario. This is because the prover may just be forwarding messages between the environment and the verifier while the environment performs all the necessary computation. In this paper we consider an l-isolated prover, which is restricted to exchanging at most l bits of information with its environment. We introduce a new notion called l-isolated proofs of knowledge (l-IPoK). These protocols securely ensure that an l-isolated prover knows the witness. To prevent the above-mentioned attack, an l-IPoK protocol has to have communication complexity greater than l. We show that for any relation in NP and any value l, there is an l-IPoK protocol for that relation. In addition, the communication complexity of such a protocol only needs to be larger than l by a constant multiplicative factor.\",\n \"Title: Practical Threshold RSA Signatures without a Trusted Dealer\\nYear: 2001\\n\\nAbstract: We propose a threshold RSA scheme which is as efficient as the fastest previous threshold RSA scheme (by Shoup), but where two assumptions needed in Shoup's and in previous schemes can be dropped, namely that the modulus must be a product of safe primes and that a trusted dealer generates the keys. The robustness (but not the unforgeability) of our scheme depends on a new intractability assumption, in addition to security of the underlying standard RSA scheme.\",\n \"Title: Perfectly secure oblivious RAM without random oracles\\nYear: 2011\\n\\nAbstract: We present an algorithm for implementing a secure oblivious RAM where the access pattern is perfectly hidden in the information theoretic sense, without assuming that the CPU has access to a random oracle. In addition we prove a lower bound on the amount of randomness needed for implementing an information theoretically secure oblivious RAM.\",\n \"Title: Unconditionally Secure and Universally Composable Commitments from Physical Assumptions.\\nYear: 2013\\n\\nAbstract: We present a constant-round unconditional black-box compiler that transforms any ideal (i.e., statistically-hiding and statisticallybinding) straight-line extractable commitment scheme, into an extractable and equivocal commitment scheme, therefore yielding to UC-security [9]. We exemplify the usefulness of our compiler by providing two (constant-round) instantiations of ideal straight-line extractable commitment based on (malicious) PUFs [36] and stateless tamper-proof hardware tokens [26], therefore achieving the first unconditionally UC-secure commitment with malicious PUFs and stateless tokens, respectively. Our constructions are secure for adversaries creating arbitrarily malicious stateful PUFs/tokens. Previous results with malicious PUFs used either computational assumptions to achieve UC-secure commitments or were unconditionally secure but only in the indistinguishability sense [36]. Similarly, with stateless tokens, UC-secure commitments are known only under computational assumptions [13,24,15], while the (not UC) unconditional commitment scheme of [23] is secure only in a weaker model in which the adversary is not allowed to create stateful tokens. Besides allowing us to prove feasibility of unconditional UC-security with (malicious) PUFs and stateless tokens, our compiler can be instantiated with any ideal straight-line extractable commitment scheme, thus allowing the use of various setup assumptions which may better fit the application or the technology available.\",\n \"Title: Lectures on Data Security, Modern Cryptology in Theory and Practice, Summer School, Aarhus, Denmark, July 1998\\nYear: 1999\\n\\nAbstract: From the Publisher: This tutorial volume is based on a summer school on cryptology and data security held in Aarhus, Denmark, in July 1998. The ten revised lectures presented are devoted to core topics in modern cryptology. In accordance with the educational objectives of the school, elementary introductions are provided to central topics, various examples are given of the problems encountered, and this is supplemented with solutions, open problems, and reference to further reading. The resulting book is ideally suited as an up-to-date introductory text for students and IT professionals interested in modern cryptology.\",\n \"Title: Oblivious Transfer from Any Non-Trivial Elastic Noisy Channels via Secret Key Agreement.\\nYear: 2016\\n\\nAbstract: A $$\\\\\\\\gamma ,\\\\\\\\delta $$ γ,﾿-elastic channel is a binary symmetric channel between a sender and a receiver where the error rate of an honest receiver is $$\\\\\\\\delta $$ ﾿ while the error rate of a dishonest receiver lies within the interval $$[\\\\\\\\gamma , \\\\\\\\delta ]$$ [γ,﾿]. In this paper, we show that from any non-trivial elastic channel i.e., $$0<\\\\\\\\gamma<\\\\\\\\delta <\\\\\\\\frac{1}{2}$$ 0<γ<﾿<12 we can implement oblivious transfer with information-theoretic security. This was previously Khurana et al., Eurocrypt 2016 only known for a subset of these parameters. Our technique relies on a new way to exploit protocols for information-theoretic key agreement from noisy channels. We also show that information-theoretically secure commitments where the receiver commits follow from any non-trivial elastic channel.\",\n \"Title: Generic Lower Bounds for Root Extraction and Signature Schemes in General Groups\\nYear: 2002\\n\\nAbstract: We study the problem of root extraction in finite Abelian groups, where the group order is unknown. This is a natural generalization of the problem of decrypting RSA ciphertexts. We study the complexity of this problem for generic algorithms, that is, algorithms that work for any group and do not use any special properties of the group at hand. We prove an exponential lower bound on the generic complexity of root extraction, even if the algorithm can choose the \\\"public exponent\\\" itself. In other words, both the standard and the strong RSA assumption are provably true w.r.t. generic algorithms. The results hold for arbitrary groups, so security w.r.t. generic attacks follows for any cryptographic construction based on root extracting. As an example of this, we revisit Cramer-Shoup signature scheme [10]. We modify the scheme such that it becomes a generic algorithm. This allows us to implement it in RSA groups without the original restriction that the modulus must be a product of safe primes. It can also be implemented in class groups. In all cases, security follows from a well defined complexity assumption (the strong root assumption), without relying on random oracles, and the assumption is shown to be true w.r.t. generic attacks.\",\n \"Title: On the Key-Uncertainty of Quantum Ciphers and the Computational Security of One-way Quantum Transmission.\\nYear: 2004\\n\\nAbstract: We consider the scenario where Alice wants to send a secret (classical) n-bit message to Bob using a classical key, and where only one-way transmission from Alice to Bob is possible. In this case, quantum communication cannot help to obtain perfect secrecy with key length smaller then n. We study the question of whether there might still be fundamental differences between the case where quantum as opposed to classical communication is used. In this direction, we show that there exist ciphers with perfect security producing quantum ciphertext where, even if an adversary knows the plaintext and applies an optimal measurement on the ciphertext, his Shannon uncertainty about the key used is almost maximal. This is in contrast to the classical case where the adversary always learns n bits of information on the key in a known plaintext attack. We also show that there is a limit to how different the classical and quantum cases can be: the most probable key, given matching plain- and ciphertexts, has the same probability in both the quantum and the classical cases. We suggest an application of our results in the case where only a short secret key is available and the message is much longer. Namely, one can use a pseudorandom generator to produce from the short key a stream of keys for a quantum cipher, using each of them to encrypt an n-bit block of the message. Our results suggest that an adversary with bounded resources in a known plaintext attack may potentially be in a much harder situation against quantum stream-ciphers than against any classical stream-cipher with the same parameters.\",\n \"Title: Secure Signature Schemes based on Interactive Protocols.\\nYear: 1995\\n\\nAbstract: Given only an interactive protocol of a certain type as a primitive, we can build a (non-interactive) signature scheme that is secure in the strongest sense of Goldwasser, Micali and Rivest (see [11]): not existentially forgeable under adaptively chosen message attacks. There are numerous examples of primitives that satisfy our conditions, e.g. Feige-Fiat-Shamir, Schnorr, Guillou-Quisquater, Okamoto and Brickell-Mc.Curley ([9], [17], [12], [15], [3]). A main consequence is that efficient and secure signature schemes can now also be based on computationally difficult problems other then factoring (see [11]), such as the discrete logarithm problem. In fact, the existence of one-way group homomorphisms is a sufficient assumption to support our construction. As we also demonstrate that our construction can be based on claw-free pairs of trapdoor permutations, our results can be viewed as a generalization of [11].\",\n \"Title: Secure Multiparty Computation Goes Live\\nYear: 2009\\n\\nAbstract: In this note, we report on the first large-scale and practical application of secure multiparty computation, which took place in January 2008. We also report on the novel cryptographic protocols that were used.\",\n \"Title: Information-Theoretically Secure MPC Against Mixed Dynamic Adversaries\\nYear: 2021\\n\\nAbstract: In this work we consider information-theoretically secure MPC against an mixed adversary who can corrupt t(p) parties passively, t(a) parties actively, and can make t(f) parties fail-stop. With perfect security, it is known that every function can be computed securely if and only if 3t(a)+2t(p)+t(f) < n, and for statistical security the bound is 2t(a)+2t(p)+ t(f) < n. These results say that for each given set of parameters (t(a), t(p), t(f)) respecting the inequality, there exists a protocol secure against this particular choice of corruption thresholds. In this work we consider a dynamic adversary. Here, the goal is a single protocol that is secure, no matter which set of corruption thresholds (t(a), t(p), t(f)) from a certain class is chosen by the adversary. A dynamic adversary can choose a corruption strategy after seeing the protocol and so is much stronger than a standard adversary. Dynamically secure protocols have been considered before for computational security. Also the information theoretic case has been studied, but only considering non-threshold general adversaries, leading to inefficient protocols. We consider threshold dynamic adversaries and information theoretic security. For statistical security we show that efficient dynamic secure function evaluation (SFE) is possible if and only if 2t(a) + 2t(p) + t(f) < n, but any dynamically secure protocol must use Omega(n) rounds, even if only fairness is required. Further, general reactive MPC is possible if we assume in addition that 2t(a) + 2t(f) <= n, but fair reactive MPC only requires 2t(a) + 2t(p) + t(f) < n. For perfect security we show that both dynamic SFE and verifiable secret sharing (VSS) are impossible if we only assume 3t(a) + 2t(p) + t(f) < n and remain impossible even if we also assume t(f) = 0. On the other hand, perfect dynamic SFE with guaranteed output delivery (G.O.D.) is possible when either t(p) = 0 or t(a) = 0 i.e. if instead we assume 3t(a) + t(f) < n or 2t(p) + t(f) < n. Further, perfect dynamic VSS with G.O.D. is possible under the additional conditions 3t(a) + 3/2t(f) <= n or 2t(p) + 2t(f) <= n. These conditions are also sufficient for dynamic perfect reactive MPC.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":125,"string":"125"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":71,"string":"71"}}},{"rowIdx":72,"cells":{"question_id":{"kind":"string","value":"Alberto Gil Solla"},"question":{"kind":"string","value":"Generate an abstract for the title \"Context-aware personalization services for a residential gateway based on the OSGi platform\" using the following items: smart homes, context-aware, personalized, OSGi platform, Semantic Web philosophy."},"answer":{"kind":"string","value":"Ideally, smart homes should make its inhabitants' lives more comfortable by anticipating their needs and satisfying their preferences. With this aim, we introduce an approach for context-aware personalized smart homes based on two main pillars: the Open Service Gateway Initiative (OSGi) platform and the Semantic Web philosophy. By combining both fields, we enrich the OSGi service-oriented architecture by providing a semantical conceptualization of (i) services at home, (ii) contextual information and (iii) inhabitants' preferences. This ontological structure supports reasoning about the captured behavior and inferring new knowledge."},"correct_answer":{"kind":"string","value":"Ideally, smart homes should make its inhabitants' lives more comfortable by anticipating their needs and satisfying their preferences. With this aim, we introduce an approach for context-aware personalized smart homes based on two main pillars: the Open Service Gateway Initiative (OSGi) platform and the Semantic Web philosophy. By combining both fields, we enrich the OSGi service-oriented architecture by providing a semantical conceptualization of (i) services at home, (ii) contextual information and (iii) inhabitants' preferences. This ontological structure supports reasoning about the captured behavior and inferring new knowledge."},"documents":{"kind":"list like","value":["Title: Enhancing Residential Gateways: A Semantic OSGi Platform\nYear: 2008\n\nAbstract: The OSGi service platform specification is the most widely adopted solution to the technological problem of building residential gateways. As in many service-oriented architectures, a service registry supports the OSGi framework by facilitating the interaction between clients and services. However, this framework has two main drawbacks. First, service discovery is based on syntactic match making, which obliges the potential client to know the concrete interface of the service it demands. Second, service invocation assumes prior knowledge of the service signatures. Both are significant obstacles in a pervasive environment such as a smart home. A semantic OSGi platform addresses this problem through a service registry that supports applying semantic reasoning to discovery and automate invocation.","Title: Downsizing Semantic Reasoning to Fixed and Mobile DTV Receivers.\nYear: 2007\n\nAbstract: Semantic reasoning is being increasingly applied in Dig- ital TV as a means to provide personalized information ser- vices. The pioneering initiatives have opted to place the personalization engines in the service providers' side, be- cause the semantic mechanisms exceed --by far-- the com- putational power of DTV receivers. Unfortunately, this ap- proach has the drawback that it can expose data about the users' interests and preferences to commercial entities, rais- ing severe legal and ethical obstacles. Moreover, in a do- main where most of the information is transmitted through broadcast, there are many cases of intermittent, sporadic or null access to a return channel, which make the personal- ization features unavailable if lodged remotely. With these problems in mind, this paper introduces an architectural ap- proach to deliver personalized DTV services, downsizing a semantic reasoning process to match the capabilities of fixed and mobile receivers. Preliminary experiments are re- ported, showing up to what point the enhanced privacy and availability impinge on personalization quality.","Title: Exploiting synergies between semantic reasoning and personalization strategies in intelligent recommender systems: A case study\nYear: 2008\n\nAbstract: Current recommender systems attempt to identify appealing items for a user by applying syntactic matching techniques, which suffer from significant limitations that reduce the quality of the offered suggestions. To overcome this drawback, we have developed a domain-independent personalization strategy that borrows reasoning techniques from the Semantic Web, elaborating recommendations based on the semantic relationships inferred between the user's preferences and the available items. Our reasoning-based approach improves the quality of the suggestions offered by the current personalization approaches, and greatly reduces their most severe limitations. To validate these claims, we have carried out a case study in the Digital TV field, in which our strategy selects TV programs interesting for the viewers from among the myriad of contents available in the digital streams. Our experimental evaluation compares the traditional approaches with our proposal in terms of both the number of TV programs suggested, and the users' perception of the recommendations. Finally, we discuss concerns related to computational feasibility and scalability of our approach.","Title: Semantic inference of user's reputation and expertise to improve collaborative recommendations\nYear: 2012\n\nAbstract: Collaborative recommender systems select potentially interesting items for each user based on the preferences of like-minded individuals. Particularly, e-commerce has become a major domain in these research field due to its business interest, since identifying the products the users may like or find useful can boost consumption. During the last years, a great number of works in the literature have focused in the improvement of these tools. Expertise, trust and reputation models are incorporated in collaborative recommender systems to increase their accuracy and reliability. However, current approaches require extra data from the users that is not often available. In this paper, we present two contributions that apply a semantic approach to improve recommendation results transparently to the users. On the one hand, we automatically build implicit trust networks in order to incorporate trust and reputation in the selection of the set of like-minded users that will drive the recommendation. On the other hand, we propose a measure of practical expertise by exploiting the data available in any e-commerce recommender system - the consumption histories of the users.","Title: A Technological Framework for TV-Supported Collaborative Learning\nYear: 2004\n\nAbstract: Interactive Digital TV is emerging as a potentially important medium to create opportunities for learning at home. To date, the offer has been mostly based on the contents available through broadcast, but this is expected to change in the near future. The increasing availability of high-quality bidirectional networks, together with the fact that IDTV users are abandoning their passive habits, envisages a new range of highly interactive services that may enhance greatly the prospects of distance education. This paper introduces a technological framework for the development and deployment of distributed and collaborative educational services for IDTV, proposing an extension to the Multimedia Home Platform standard. The framework is based on a selection of freely available technologies, which we integrate into a CASE tool that bridges the gap between course-authoring and programming tasks. We also discuss the possible market implications of our approach, because the ideas presented here contribute to openness in the field of IDTV services, so far monopolised by mainstream broadcasters.","Title: Incentivized provision of metadata, semantic reasoning and time-driven filtering: Making a puzzle of personalized e-commerce\nYear: 2010\n\nAbstract: e-Commerce recommender systems select potentially interesting products for users by looking at their purchase histories and preferences. In order to compare the available products against those included in the user's profile, semantics-based recommendation strategies consider metadata annotations that describe their main attributes. Besides, to ensure successful suggestions of products, these strategies adapt the recommendations as the user's preferences evolve over time. Traditional approaches face two limitations related to the aforementioned features. First, product providers are not typically willing to take on the tedious task of annotating accurately a huge diversity of commercial items, thus leading to a substantial impoverishment of the personalization quality. Second, the adaptation process of the recommendations misses the time elapsed since the user has bought an item, which is an essential parameter that affects differently to each purchased product. This results in some pointless recommendations, e.g. including regularly items that the users are only willing to buy sporadically. In order to fight both limitations, we propose a personalized e-commerce system with two main features. On the one hand, we incentivize the users to provide high-quality metadata for commercial products; on the other, we explore a strategy that offers time-aware recommendations by combining semantic reasoning about these annotations with item-specific time functions. The synergetic effects derived from this combination lead to suggestions adapted to the particular needs of the users at any time. This approach has been experimentally validated with a set of users who accessed our personalized e-commerce system through a range of fixed and handheld consumer devices.","Title: Semantic Query Validation in Guided-Based Systems: Assuring the Construction of Queries that Make Sense\nYear: 2010\n\nAbstract: Semantic search importance is growing each day as millions of people around the world need to obtain objective and concrete information. Guided-based systems are an alternative to natural language systems regarding the query construction method. However, current guided-based systems perform query validation only at a syntactical level. In this paper we address the semantic validation of queries in order to avoid redundancy and incoherency, therefore preventing the formulation of queries that do not make sense.","Title: Enhancing TV programmes with additional contents using MPEG-7 segmentation information\nYear: 2010\n\nAbstract: Interactive Digital TV offers a large amount of TV channels, as well as new contents that come along with the TV programmes. To take advantage of these additional contents and make them easily available to viewers, this paper proposes to offer additional contents linked to the segments of TV programmes by means of semantic relations obtained using MPEG-7 segmentation information. As a practical use of this work, we propose two different application fields: t-learning, with the aim of using TV programmes to engage viewers in education; and personalised advertising, whose goal is offering viewers products of their interest, maximising its effectiveness.","Title: Multi-valued model checking in dense-time\nYear: 2005\n\nAbstract: In this paper we introduce $\\mathcal{X}$TCTL, a dense-time extension of the multi-valued Computation Tree Logic ($\\mathcal{X}$CTL) in [1]. Alternatively, $\\mathcal{X}$TCTL is a multi-valued extension of TCTL [2] over quasi-boolean algebras. A multi-valued quotient is defined which enables to reduce dense-time $\\mathcal{X}$TCTL model checking to the untimed case.","Title: KEPPAN: Knowledge exploitation for proactively-planned ad-hoc networks\nYear: 2009\n\nAbstract: This paper explores the idea of managing mobile ad-hoc networks (MANETs) by the communication needs of their nodes, as a means to facilitate the operation of distributed applications. Specifically, we present a middleware layer that enables reasoning about the multiple possibilities there may exist to ensure satisfiability of certain communication needs. This middleware has been explicitly devised to handle partial and changeable knowledge about the networks, and to guide the search for missing information whenever it cannot conclude whether it will be possible to satisfy some needs. These features provide the basis to implement policies with which to coordinate activities in a MANET, in quest for the configuration that best satisfies the communication needs of its nodes. We provide simulation results to show the comparative advantages of our solution, plus a report of experiments to assess its practicality and usability.","Title: Personalizing e-Commerce by Semantics-Enhanced Strategies and Time-Aware Recommendations.\nYear: 2008\n\nAbstract: Current e-commerce recommender systems adapt the selection of commercial items suggested to the users as their preferences evolve over time. However, this adaptation process misses the time elapsed since the user has bought an item, which is an essential parameter that affects differently to each purchased product. This results in some useless recommendations, including regularly items that the users are only willing to buy sporadically. In this paper, we explore a new recommendation strategy that offers time-aware suggestions to e-commerce users, by enhancing reasoning techniques from the Semantic Web with item-dependent time functions. This combination leads to suggestions adapted to the particular needs of each user at any given moment.","Title: REENACT: A step forward in immersive learning about Human History by augmented reality, role playing and social networking.\nYear: 2014\n\nAbstract: •A technology-driven edutainment approach for immersive group learning about History.•Use of handheld devices, social networks, role playing, AR and multimedia contents.•Good results in Quality of Service (QoS), Community (QoC) and Experience (QoE).","Title: Leveraging Short-Lived Social Networks in Museums to Engage People in History Learning\nYear: 2013\n\nAbstract: The interactions enabled by the popular sites of the Web 2.0 are largely confined to the virtual world of the Internet, thus failing to engage people in relevant interactions with people, contents or resources in their physical environment. In this paper, we motivate the potential of automatically establishing sporadic social networks among people (acquaintances or strangers) who happen to be physically close to one another at a certain moment. We present the design of one platform intended to provide solutions from the lowest level of establishing ad-hoc connections among nearby mobile devices, up to the highest level of automatically identifying the most relevant pieces of information to deliver at any time. One specific scenario is discussed for museum environments, considering the possibility of engaging groups of people into immersive collective experiences to learn about major historical events.","Title: AVATAR: A Multi-Agent TV Recommender System using MHP Applications\nYear: 2005\n\nAbstract: In this paper we present AVATAR, a recommender of personalized TV contents, for which an open multi-agent architecture is proposed. This tool uses different knowledge inference strategies, even though we focus on the description of one of them, the naive Bayesian classifiers. Standardization is a key issue to achieve wide deployment in this kind of systems. So, the described recommendation tool has been conceived as an application conforming to Multimedia Home Platform (MHP) standard, to be distributed in the broadcast transport stream that will be tuned by each user's receiver. Also, the TV-Anytime specification has been used referred to the description of contents, the users preferences and their activity logs.","Title: An MHP framework to provide intelligent personalized recommendations about digital TV contents\nYear: 2008\n\nAbstract: Digital Television will bring a significant increase in the amount of channels and programs available to end users, with many more difficulties to find contents appealing to them among a myriad of irrelevant information. Thus, automatic content recommenders should receive special attention in the following years to improve their assistance to users. The current content recommenders have important deficiencies that hamper their wide acceptance. In this paper, we present a new approach for automatic content recommendation that significantly reduces those deficiencies. This approach, based on Semantic Web technologies, has been implemented in the AdVAnced Telematic search of Audiovisual contents by semantic Reasoning tool, a hybrid content recommender that makes extensive use of well-known standards, such as Multimedia Home Platform, TV-Anytime and OWL. Also, we have carried out an experimental evaluation, the results of which show that our proposal performs better than other existing approaches. Copyright © 2007 John Wiley & Sons, Ltd.","Title: Exploring synergies between content-based filtering and Spreading Activation techniques in knowledge-based recommender systems.\nYear: 2011\n\nAbstract: Recommender systems fight information overload by selecting automatically items that match the personal preferences of each user. The so-called content-based recommenders suggest items similar to those the user liked in the past, using syntactic matching mechanisms. The rigid nature of such mechanisms leads to recommending only items that bear strong resemblance to those the user already knows. Traditional collaborative approaches face up to overspecialization by considering the preferences of other users, which causes other severe limitations. In this paper, we avoid the intrinsic pitfalls of collaborative solutions and diversify the recommendations by reasoning about the semantics of the user’s preferences. Specifically, we present a novel content-based recommendation strategy that resorts to semantic reasoning mechanisms adopted in the Semantic Web, such as Spreading Activation techniques and semantic associations. We have adopted these mechanisms to fulfill the personalization requirements of recommender systems, enabling to discover extra knowledge about the user’s preferences and leading to more accurate and diverse suggestions. Our approach is generic enough to be used in a wide variety of domains and recommender systems. The proposal has been preliminary evaluated by statistics-driven tests involving real users in the recommendation of Digital TV contents. The results reveal the users’ satisfaction regarding the accuracy and diversity of the reasoning-driven content-based recommendations.","Title: The multimedia home platform (MHP) framework for web access through digital TV\nYear: 2003\n\nAbstract: The DVB Consortium has recently published the MHP standard to regulate the execution of interactive applications in digital TV, including an Internet profile for web access. In this communication, that profile is analysed.","Title: User-generated contents and reasoning-based personalization: Ingredients for a novel model of mobile TV\nYear: 2011\n\nAbstract: During the last years, we have witnessed the boom of the digital market due to the proliferation of emergent audiovisual services and the increasing number of broadband networks. In this scenario, users insistently demand innovative services for exchanging and sharing their own audiovisual contents. In order to meet these needs, in this paper we propose a system that broadcasts user-generated audiovisual contents for handheld devices in a mobile network based on the DVB-H broadcasting standard. Besides, our system offers diverse added-value services to these new active users, such as: (i) multi modal access (via Web or by client applications running locally in handheld devices) to digital contents, (ii) exploitation of return channels to transmit interactive contents that enhance the user's experience, and (iii) annotation, sharing and personalized distribution of audiovisual contents. To achieve these goals, our system adopts well-known technologies for broadcasting and semantic annotation of audiovisual contents, as well as emergent technology from the so-called Web 2.0. A prototype of our system has been experimentally evaluated with a group of students from the University of Vigo, who were enthusiastic about the personalization capabilities offered by our TV system for a mobile setting.","Title: A Core of Standards to Support T-learning\nYear: 2006\n\nAbstract: The possibility of transmitting interactive applications along with the audiovisual contents will turn the television into a universal platform to access the Information Society. Nowadays, there is growing interest in exploiting that potential to develop distance learning policies, to supplement the facilities offered by the current e-learning technologies. This short paper describes the implementation of a software module that enables the provision of educational services over Interactive Digital TV (t-learning). This module has been designed according to the technical peculiarities of an IDTV receiver, and resorts to existing standards to favor the convergence of all distance learning mediums.","Title: Provision of distance learning services over Interactive Digital TV with MHP\nYear: 2008\n\nAbstract: E-learning technologies have developed greatly in recent years, with considerable success. However, there is increasing evidence that web-based learning is not reaching the social sectors which are more reluctant to contact with the new technologies, thus leading to inequalities in the access to education and knowledge in the Information Society. By hiding the intricacies of computers behind the familiarity of household equipment, Interactive Digital TV (IDTV) is considered to play a key role in addressing this problem, and the term t-learning has been recently coined to mean TV-based interactive learning. Despite several approaches to t-learning have been proposed, works are missing that conceive it as a whole, delimit its scope in comparison with web-based learning and analyze the influence of the normalization of IDTV as a services platform. This paper addresses these issues, and introduces a framework for the development and deployment of t-learning services that promotes interoperability and reuse while taking into account the characteristic features of the IDTV medium.","Title: Improving e-Commerce Collaborative Recommendations by Semantic Inference of Neighbors' Practical Expertise.\nYear: 2011\n\nAbstract: E-commerce has become a major application domain for recommender systems due to its business interest. These tools aim to identify the products each user may like or find useful, which can boost users' consumption. Particularly, collaborative recommender systems rely on a set of like-minded users to select the products to offer. Taking into account the expertise of the users who drive such decision can increase the accuracy of the process. However, current approaches require extra data, that is not often available, to obtain expertise measures. In this paper, we apply a semantic approach to get a measure of practical expertise by exploiting the data available in any e-commerce recommender system-the consumption histories of the users. This way, we improve recommendation results transparently to the users.","Title: Semantic Reasoning and Mashups: An Innovative Approach to Personalized E-Commerce in Digital TV.\nYear: 2009\n\nAbstract: The potential of Digital TV for e-commerce remains heavily underexploited, mainly because there are no systematic approaches to the provision of applications to browse information about the advertised items, to purchase them online, etc. We present a procedure to automatically compose interactive applications that provide personalized commercial functionalities to the users, gathering contents from multiple sources and with a back-end of semantic web services. The procedure is driven SWRL rules and similarity metrics based on semantic reasoning.","Title: AVATAR: an approach based on semantic reasoning to recommend personalized TV programs\nYear: 2005\n\nAbstract: In this paper a TV recommender system called AVATAR (AdVAnce Telematic search of Audiovisual contents by semantic Reasoning) is presented. This tool uses the experience gained in the field of the Semantic Web to personalize the TV programs shown to the end users. The main contribution of our system is a process of semantic reasoning carried out on the descriptions of the TV contents ---provided by means of metainformation--- and on the viewer preferences --- contained in personal profiles. Such process allows to diversify the offered suggestions maintaining the personalization, given that the aim is to find contents appealing for the users, which are related semantically to their programs of interest.Here the framework proposed for this reasoning is introduced, by including (i) the OWL ontology chosen to represent the knowledge of our application domain, (ii) the organization of the user profiles, (iii) the query language LIKO, which is intended to browse the ontology and (iv) the semantic relations inferred from the system knowledge base.","Title: Tracing integration analysis in component-based formal specifications\nYear: 2005\n\nAbstract: The correctness of a component-based specification is not guaranteed by the correctness of its components alone; on the contrary, integration analysis is needed to observe their conjoint behavior. Existing approaches often leave the results of the analysis at the level of the integrated system, without tracing them onto the corresponding components. This effectively results in loss of architecture, as it is no longer possible to reason over those components and evolve their specification while keeping the results of integration analysis. This paper presents a formal approach to automatically translate changes on the integrated system into revisions of the components and the architecture initially defined by the developers. Several architectural alternatives are provided that, besides allowing developers to reason about the system from different points of view, promote its correct modularization in two overlapping perspectives: the encapsulation of crosscutting concerns and the elaboration of the architecture desired for the final implementation.","Title: ATLAS: a framework to provide multiuser and distributed t-learning services over MHP\nYear: 2006\n\nAbstract: The increasing need of the developed countries to carry out effective distance learning strategies has led to a great development of Internet-based learning technologies (e-learning). Despite its evident advantages, the expansion of e-learning has been limited by the difficulty in reaching important social sectors, and also by the absence of mechanisms to fight the feeling of isolation of the users, which often leads them to abandoning the distance learning activities. This paper tackles these problems by introducing ATLAS, a framework for the development and deployment of multiuser t-learning services (i.e. learning services over Interactive Digital TV). This framework is built around three major features: an architecture for the services that exploits the multimedia capabilities of the television, a communications infrastructure that promotes the establishment of virtual learning communities, and a development tool that allows services to be created with minimum programming knowledge. ATLAS has been designed by considering several features that make Interactive Digital TV quite different from the PC, advising against the direct translation of the models developed for the Internet. In particular, ATLAS adheres to the Multimedia Home Platform (MHP) standard, which is gaining worldwide acceptance as one of the technical solutions that will shape the future of Interactive Digital TV. Copyright © 2006 John Wiley & Sons, Ltd.","Title: Methodologies to evolve formal specifications through refinement and retrenchment in an analysis–revision cycle\nYear: 2009\n\nAbstract: The development of requirement specifications is done by accumulating knowledge about the desired systems in a progressive manner. This process can be supported by an analysis–revision cycle, in which the analysis phase checks the correctness of a given specification, and the revision phase modifies it, in case some problems are detected. To date, the analysis and revision activities have been typically considered in isolation, resulting in ineffective support to the stakeholders’ work. In response to that, this article introduces methodologies to conduct an interactive and integrated approach, grounded on the formalization of two basic types of evolutions (refinements and retrenchments) over multi-valued specification and modeling formalisms. Evaluation results are included to show that this approach can indeed help the stakeholders identify and clarify requirements through different stages of development.","Title: Automatic Query Generation in Guided Systems: Natural Language Generation from Graphically Built Query\nYear: 2010\n\nAbstract: Guided-based systems are an alternative to natural language systems regarding the query construction method. We present a new solution that bridges the gap between these two types of systems by providing a hybrid interface which combines a graphical query interface for query construction with the correspondent natural language expression automatically generated by the system.","Title: An extension to the ADL SCORM standard to support adaptivity: The t-learning case-study\nYear: 2009\n\nAbstract: Current e-learning standards have been designed to provide reusability and interoperability. Besides these features, content personalisation is also necessary, although current standards do not fully support it. In this paper, we study the adaptation possibilities of the SCORM standard and present an extension to permit adaptivity according to user's characteristics. It comprises a syntax for adaptivity rules based on a set of adaptation parameters. The actual values of these adaptation parameters are deduced from the user profile, using inference rules. As a result, adaptive courses are obtained, created with the aim of being personalised before shown to the student.","Title: ZapTV: Personalized User-Generated Content for Handheld Devices in DVB-H Mobile Networks\nYear: 2008\n\nAbstract: During the last years, we had witnessed the boom of the digital market due to proliferation of emergent audiovisual services and increasing number of broadband networks. In this scenario, users insistently demand for innovative services for exchanging and sharing their own audiovisual contents and productions. In order to meet these needs, in this paper we propose the ZapTV system. Broadly speaking, this tool broadcasts user-generated audiovisual contents for handheld devices in a mobile network based on the DVB-H broadcasting standard. ZapTV offers diverse added-value services to these new active users, such as: (i) multi modal access (via Web and by handheld devices) to digital contents anywhere and anytime, (ii) availability of a return channel to transmit interactive contents that enhance the user's viewing experience, and (iii) annotation, sharing and personalized distribution of audiovisual contents. To achieve these goals, our system adopts both well-known technologies for broadcasting and semantic annotation of audiovisual contents (such as DVB-H and TV-Anytime), and emergent technology from the so-called Web 2.0, which permit the users to actively cooperate in tasks of generation, annotation and classification of digital contents.","Title: REENACT: Augmented reality and collective role playing to enhance the pedagogy of historical events an EXPERIMEDIA experiment\nYear: 2013\n\nAbstract: Much of human history has been shaped by the outcomes of countless battles and wars. Unfortunately, the classical pedagogy of these events merely tells about who were the belligerent forces, how long the fights lasted for, and who ended up winning. We present one proposal to engage groups of people into immersive collective experiences that will make them learn about a certain battle or war both from the inside, as reenactors, and from the outside, as historians. The participants will be equipped with smartphones or tablets that interact with the technological facility developed within the EXPERIMEDIA FP7 project, which provides support for the implementation, deployment and execution of distributed live games, social networking features and augmented reality.","Title: Semantic reasoning: a path to new possibilities of personalization\nYear: 2008\n\nAbstract: Recommender systems face up to current information overload by selecting automatically items that match the personal preferences of each user. The so-called content-based recommenders suggest items similar to those the user liked in the past, by resorting to syntactic matching mechanisms. The rigid nature of such mechanisms leads to recommend only items that bear a strong resemblance to those the user already knows. In this paper, we propose a novel content-based strategy that diversifies the offered recommendations by employing reasoning mechanisms borrowed from the SemanticWeb. These mechanisms discover extra knowledge about the user's preferences, thus favoring more accurate and flexible personalization processes. Our approach is generic enough to be used in a wide variety of personalization applications and services, in diverse domains and recommender systems. The proposed reasoning-based strategy has been empirically evaluated with a set of real users. The obtained results evidence computational feasibility and significant increases in recommendation accuracy w.r.t. existing approaches where our reasoning capabilities are disregarded.","Title: Guidelines for the incremental identification of aspects in requirements specifications\nYear: 2006\n\nAbstract: The desired principle of separation of concerns in software development can be jeopardized by the so-called crosscutting concerns, which tend to be scattered over (and tangled with) the functionality of the modular units of a system. The correct identification of such concerns (and their encapsulation into separate artifacts) is thereby considered a way to improve software understanding and evolution. Pursuing a proper management of concerns from the requirements engineering stage can greatly benefit the entire software life-cycle. In this paper, we propose conceptual guidelines on how to perform the identification of crosscutting concerns in the process of building requirements specifications. We argue that the identification must be carried out in an incremental way, to encapsulate apart the crosscutting concerns even if they have not emerged completely yet.","Title: Application-level assessment of approaches to coordinate node mobility in wireless sensor and actor networks\nYear: 2010\n\nAbstract: Wireless networks of sensor and actor devices require a great deal of coordination to fulfil their objectives. This paper focuses on the dimension of actor-actor coordination, that involves analyzing the data gathered by the sensors and deciding how to act on the environment. Specifically, we tackle the open problem of considering the effects of actors' mobility on the communications needed for coordination. Firstly, we define three general approaches to bring mobility concerns into coordination, adapting solutions from the field of ad-hoc networking. Then, we assess the strengths and weaknesses of the three approaches through simulations of an autonomous robotic system in a representative application scenario, namely the extinction of forest fires. The results reveal trade-offs among performance, delays in communication, sensitiveness to timing and positioning imprecisions, and energy consumption.","Title: MHP-OSGi convergence: a new model for open residential gateways\nYear: 2006\n\nAbstract: Nowadays, we are living in a time of important technological changes that affect our lives at home and our communication with the outside world. Among them, the developments in Interactive Digital TV (IDTV) and the smart home field can be considered as particularly important. Related to the former, the new Set-Top Boxes (STBs) are not only a decoder for digital television broadcast but also an entry point to the Information Society and a suitable platform to support the execution of interactive applications. With regards to the latter, the Residential Gateways (RGs) combine different network technologies to allow the connection of different electronics devices and appliances at home, not only with each other but also with the Internet. Since there is no widespread consensus about the configurations and functions of the RGs, we propose to coordinate the two aforementioned worlds by extending the functionality of STBs to become a RG. Our proposal consists of merging the Multimedia Home Platform (MHP), one of the main standard frameworks for IDTV, with Open Service Gateway Initiative (OSGi), the most widely used open platform to set up RGs. To overcome the radically different nature of these specifications—the function-oriented MHP middleware and the service-oriented OSGi framework—we define a new kind of application, coined as XbundLET. This application is able to bridge the gap between the two frameworks and make their interaction feasible. We also show how this proposal has the potential to enable the production of scenarios that cannot currently be put into practice in a natural way. Copyright © 2006 John Wiley & Sons, Ltd.","Title: Bringing Content Awareness to Web-Based IDTV Advertising\nYear: 2012\n\nAbstract: In the new technological context of interactive digital (IDTV), traditional TV spots are expected to be replaced by interactive applications. In this paper, we propose a new TV advertising architecture inspired by the philosophy and business models of online advertising. Personalization and content awareness are the two mainstays of our approach that allow advertisers to have more efficient campaigns focused on a targeted audience.","Title: Collaborative T-learning: Bringing Greater Levels of Interactivity into the Home\nYear: 2005\n\nAbstract: T-learning -the provision of educational services over Interactive Digital TV-is emerging as a important medium to create opportunities for learning at home. In this paper, we elaborate on a framework for the development and deployment of collaborative t-learning services, presenting an architecture that allows distributing the logic of a service, a way to define complex interaction patterns among users and a network infrastructure that provides adequate support for the communication needs.","Title: A semantic approach to avoiding fake neighborhoods in collaborative recommendation of coupons through digital TV\nYear: 2010\n\nAbstract: Consumers are flooded with amounts of discount coupons, oftentimes for products that are far from their interests. This marketing custom is already rising on the Internet and is imminent in Digital TV, where the massive sending of coupons leads to their devaluation and consumer indifference. The computing capabilities of these media permit to alleviate this problem by means of recommender systems, which are very useful tools in application domains that suffer from information overload. However, current recommender systems overlook the diversity of products and services available in the market, which gives rise to forming fake neighborhoods in collaborative filtering strategies. In this paper, we apply semantic reasoning techniques to avoid such fake neighborhoods and, thereby, improve the recommendation process. Furthermore, taking advantage of the Digital TV medium, we propose matching the recommended coupons to TV contents semantically related with them, in order to increase their redemption.","Title: T-MAESTRO and its authoring tool: using adaptation to integrate entertainment into personalized t-learning\nYear: 2008\n\nAbstract: Interactive Digital TV opens new learning possibilities where new forms of education are needed. On the one hand, the combination of education and entertainment is essential to boost the participation of viewers in TV learning (t-learning), overcoming their typical passiveness. On the other hand, researchers broadly agree that in order to prevent the learner from abandoning the learning experience, it is necessary to take into account his/her particular needs and preferences by means of a personalized experience. Bearing this in mind, this paper introduces a new approach to the conception of personalized t-learning: edutainment and entercation experiences. These experiences combine TV programs and learning contents in a personalized way, with the aim of using the playful nature of TV to make learning more attractive and to engage TV viewers in learning. This paper brings together our work in constructing edutainment/entercation experiences by relating TV and learning contents. Taking personalization one step further, we propose the adaptation of learning contents by defining A-SCORM (Adaptive-SCORM), an extension of the ADL SCORM standard. Over and above the adaptive add-ons, this paper focuses on two fundamental entities for the proposal: (1) an Intelligent Tutoring System, called T-MAESTRO, which constructs the t-learning experiences by applying semantic knowledge about the t-learners; and (2) the authoring tool which allow teachers to create adaptive courses with a minimal technical background.","Title: Avoiding Fake Neighborhoods in e-Commerce Collaborative Recommender Systems: A Semantic Approach.\nYear: 2009\n\nAbstract: Recommender systems are very useful tools inapplication domains that suffer from information overload,offering the users suggestions they may be interested in.Owing to its business interest, e-commerce has become amajor domain in this research field, since identifying thoseproducts that the users will appreciate could increase users’consumption. However, current e-commerce recommendersystems overlook some implications of the great diversity ofproducts and services available in the market, giving rise toform fake neighborhoods in collaborative filtering strategies.In this paper, we propose applying semantic reasoning techniquesto solve this problem, thus improving, qualitativelyand computationally, the recommendation process.","Title: A flexible semantic inference methodology to reason about user preferences in knowledge-based recommender systems\nYear: 2008\n\nAbstract: Recommender systems arose with the goal of helping users search in overloaded information domains (like e-commerce, e-learning or Digital TV). These tools automatically select items (commercial products, educational courses, TV programs, etc.) that may be appealing to each user taking into account his/her personal preferences. The personalization strategies used to compare these preferences with the available items suffer from well-known deficiencies that reduce the quality of the recommendations. Most of the limitations arise from using syntactic matching techniques because they miss a lot of useful knowledge during the recommendation process. In this paper, we propose a personalization strategy that overcomes these drawbacks by applying inference techniques borrowed from the Semantic Web. Our approach reasons about the semantics of items and user preferences to discover complex associations between them. These semantic associations provide additional knowledge about the user preferences, and permit the recommender system to compare them with the available items in a more effective way. The proposed strategy is flexible enough to be applied in many recommender systems, regardless of their application domain. Here, we illustrate its use in AVATAR, a tool that selects appealing audiovisual programs from among the myriad available in Digital TV.","Title: Receiver-side semantic reasoning for digital TV personalization in the absence of return channels\nYear: 2009\n\nAbstract: Experience has proved that interactive applications delivered through Digital TV must provide personalized information to the viewers in order to be perceived as a valuable service. Due to the limited computational power of DTV receivers (either domestic set-top boxes or mobile devices), most of the existing systems have opted to place the personalization engines in dedicated servers, assuming that a return channel is always available for bidirectional communication. However, in a domain where most of the information is transmitted through broadcast, there are still many cases of intermittent, sporadic or null access to a return channel. In such situations, it is impossible for the servers to learn who is watching TV at the moment, and so the personalization features become unavailable. To solve this problem without sacrificing much personalization quality, this paper introduces solutions to run a downsized semantic reasoning process in the DTV receivers, supported by a pre-selection of material driven by audience stereotypes in the head-end. Evaluation results are presented to prove the feasibility of this approach, and also to assess the quality it achieves in comparison with previous ones.","Title: MiSPOT: dynamic product placement for digital TV through MPEG-4 processing and semantic reasoning\nYear: 2010\n\nAbstract: In an increasingly competitive market, stakeholders of the television industry strive to exploit all the possibilities to get revenues from advertising, but their practices are usually at odds with the comfort of the TV viewers. This paper presents the proof of concept of MiSPOT, a system that brings a non-invasive and fully personalized form of advertising to Interactive Digital TV, targeting both domestic and mobile receivers. MiSPOT employs semantic reasoning techniques to select advertisements suited to the preferences, interests and needs of each individual viewer, and then relies on multimedia composition abilities to blend the advertising material with the TV program he/she is viewing at any time. The advertisements can be set to launch interactive commercials, thus enabling means for the provision of t-commerce services. Evaluation experiments are described to show the technical viability of the proposal, and also to gauge the opinions of end users. Questions about the potential impact and exploitation of this new form of advertising are addressed too.","Title: A Multi-Agent Open Architecture for a TV Recommender System: A Case Study Using a Bayesian Strategy\nYear: 2004\n\nAbstract: In this paper we present a recommender system of personalized TV contents, called AVATAR1, for which we propose a modular multi-agent architecture, that combines different knowledge inference strategies (such as Bayesian techniques, profiles matching and semantic reasoning). We focus on the description of one of these strategies, the naive Bayesian classifiers, explaining an example in the context of personalized digital television. In order to represent the knowledge in the television domain, we have developed a TV contents ontology, to infer new data from the known information. Besides, the TV-Anytime specification has been used referred to the description of contents and the management of user preferences and their activity logs. The proposed recommender system has been conceived as an application conforming to Multimedia Home Platform (MHP) standard, to be distributed over the broadcast transport stream that will be tuned by the user receiver.","Title: Spontaneous interaction with audiovisual contents for personalized e-commerce over Digital TV\nYear: 2009\n\nAbstract: The development of the Interactive Digital TV technologies has the potential to open new possibilities for e-commerce, linked to the broadcasting of audiovisual contents. To cater for the advertising needs, the early initiatives are resorting to the techniques traditionally employed by the television industry, which have proven deficiencies related to targeting and viewers' comfort. In response to that, we have developed a new advertising model, based on identifying products semantically related to the things that draw the viewer's attention on the screen. Thereupon, a personalization engine selects the products which are potentially interesting for the viewer, and assembles interactive services that provide him/her with tailor-made commercial functionalities. This paper provides guidelines on how to support the proposed model over the technological basis of the modern Digital TV receivers (either domestic or mobile ones), and describes a sample scenario of personalized advertising.","Title: Incremental specification with SCTL/MUS-T: a case study\nYear: 2004\n\nAbstract: The past decade witnessed a great advance in the field of timed formal methods for the specification and analysis of real-time and safety-critical systems. In this context, timed automata and real-time temporal logics provide a simple, and yet general, way to model and specify the behavior of these systems. At the same time, iterative and incremental development has been massively adopted in professional practice. In order to get closer to this current trend, timed formal methods should be adapted to such lifecycle structures, getting over their traditional role of verifying that a model meets a set of fixed requirements. In the pursuit of this ultimate aim, we propose SCTL/MUS-T, a timed methodology in which many-valuedness let deal with both the uncertainty and the disagreement which are pervasive and desirable in an iterative and incremental process. To illustrate the main ideas behind SCTL/MUS-T methodology this paper focuses on the specification, synthesis and verification of the well known steam-boiler case study.","Title: Formal specification applied to multiuser distributed services: experiences in collaborative t-learning\nYear: 2006\n\nAbstract: The development of multiuser and distributed software systems faces the difficulty to program the applications correctly, in a way that guarantees the desired interaction among the users. Motivated by experiences with collaborative t-learning services (i.e. multiuser educational services over Interactive TV), this paper presents a solution to that problem, based on supplementing visual development with formal specification techniques. As a contribution to the development of interactive systems, a software process is introduced that helps defining the separate and the conjoint behavior of different users, incrementally and using highly-accessible formalisms.","Title: A Six-valued Logic to Reason about Uncertainty and Inconsistency in Requirements Specifications\nYear: 2006\n\nAbstract: The development of requirements specifications is characterized by the uncertain and changeable knowledge available about the systems to be built. This paper presents a many-valued logic that enables effective reasoning about uncertainty and inconsistency in requirements specifications, motivating the election of six truth values and the definition of a new implication connective. The adequacy of this logic to support a formal development methodology is assessed through a comparison with Belnap's four-valued logic in combination with the classical implications.","Title: Making the most of TV on the move: My newschannel\nYear: 2011\n\nAbstract: The increasing success of mobile-TV (m-TV) is changing the habits and customs in TV consumption which now extends to parts of the day when viewers are not at home and, mainly, within short intervals between other daily activities. Since much m-TV consumption will be in spare time, offering the users contents they are interested in becomes extremely important to provide an attractive service which does not discourage potential users. Using DVB-H as transport infrastructure, in this paper we introduce a personalization architecture which perfectly fits in with the value chain of m-TV. By applying semantic models and techniques, personalized virtual channels are dynamically constructed by adequately combining several kinds of contents according to the user's interests. While the personalization architecture is particularized, in this paper, to provide news channels, it could be easily generalized to other fields.","Title: Collaborative and role-play strategies in software engineering learning with web 2.0 tools\nYear: 2014\n\nAbstract: Software development processes are inherently complex and require the collaboration and coordination of expert teams. The acquisition of both analysis and design competences as well as social skills should thus be the leitmotiv of courses devoted to software engineering learning. However, these aspects are often ignored and excessive importance is attached to the implementation stage. The learning framework described in this article was designed to teach students these competences and skills by means of an immersive learning experience where, working in a team, each student has to play the role of a software developer and address problems linked to requirements specification, design, and the software development process as a whole. Collaborative strategies of this kind have proven to be very successful in active learning processes, to which we have added continuous assessment mechanisms based on rubrics to provide early feedback to students. Additionally, and taking into account the characteristics of the new European Space for Higher Education, we have designed an online personal learning environment (PLE) that facilitates anytime-anywhere communications and provides a suitable social space for the exchange of information, which is crucial to the success of any teamwork effort. More specifically, we propose a learning activity based on Web 2.0 services and adapted to this particular PLE.(c) 2012 Wiley Periodicals, Inc. Comput Appl Eng Educ 22:658-668, 2014; View this article online at ; DOI","Title: An improved virtualization layer to support distribution of multimedia contents in pervasive social applications\nYear: 2015\n\nAbstract: Pervasive social computing is a new paradigm of computer science that aims to facilitate the realization of activities in whichever context, with the aid of information devices and considering social relations between users. This vision requires means to support the shared experiences by harnessing the communication and computing capabilities of the connected devices, relying on direct or hop-by-hop communications among people who happen to be close to each other. In this paper, we present an approach to turn mobile ad-hoc networks (MANETs) into stable communication environments for pervasive social applications. The proposal is based on an evolution of the VNLayer, a virtualization layer that defined procedures for mobile devices to collaboratively emulate an infrastructure of stationary virtual nodes. We refine the VNLayer procedures and introduce new ones to increase the reliability and the responsiveness of the virtual nodes, which serves to boost the performance of routing with a virtualized version of the well-known AODV algorithm. We prove the advantages of the resulting routing scheme by means of simulation experiments and measurements on a real deployment of an application for immersive and collective learning about History in museums and their surroundings.","Title: A semantic approach to improve neighborhood formation in collaborative recommender systems\nYear: 2014\n\nAbstract: utomatic recommenders are now omnipresent in e-commerce websites, as selecting and offering to users products they may be interested in can considerably increase sales revenue. The most popular recommendation strategy is currently considered to be the collaborative filtering technique, based on offering to the user who will receive the recommendation items that were appealing to other individuals with similar preferences (the so-called neighbors). On the other hand, its principal obstacle is the sparsity problem, related to the difficulty to find overlappings in ratings when there are many items. As the product catalogue of these sites gets more and more diverse, a new problem has arisen that happens when users share likings for lots of products (for which they are reckoned to be neighbors) but they differ in products similar to the one that is being considered for recommendation. They are fake neighbors. Narrowing the range of products on which similarities between users are sought can help to avoid this, but it usually causes a worsening of the sparsity problem because the chances of finding overlappings gets lower. In this paper, a new strategy is proposed based on semantic reasoning that aims to improve the neighborhood formation in order to overcome the aforementioned fake neighborhood problem. Our approach is aimed at making more flexible the search for semantic similarities between different products, and thus not require users to rate the same products in order to be compared.","Title: An Affordable And Inclusive System To Provide Interesting Contents To Dtv Using Recommender Systems\nYear: 2012\n\nAbstract: This paper presents a television scheduling system that aims to aid developing countries in digital television transition by providing content interesting for the people while reducing content acquisition costs. It is based on recommender systems for audiovisual content with special considerations for groups of viewers. The system proposed is fed with content uploaded by the people, properly classified. In a first and basic scenario the system generates four different thematic signals with predefined genres. In the second one, the profile for each user is known and audience is modeled as a group of viewers with known user profiles, allowing its segmentation and channel scheduling according to actual preferences.","Title: Optimising Reactive Routing over Virtual Nodes in VANETs\nYear: 2016\n\nAbstract: The Virtual Node Layer (VNLayer) is a clusterbased approach to handle communications in mobile ad-hoc networks (MANETs), furnishing an abstraction of fixed geographical regions served by virtual nodes as a means to tackle the challenges raised by the mobility of the physical nodes. Several studies have proved that the VNLayer constructs can be applied to improve the performance of existing routing algorithms – most notably, AODV– in general MANET scenarios. In this paper, however, we show that the same mechanisms do not work well in the more specific and demanding realm of vehicular ad-hoc networks (VANETs). In response to that, we present several enhancements to the reference implementations of the VNLayer and the adaptation of AODV to work with virtual nodes, proving by means of mathematical analysis and simulation experiments that our solutions achieve better performance in terms of overhead, packet delivery fraction and latencies in VANET scenarios.","Title: Augmented reality, smart codes and cloud computing for personalized interactive advertising on billboards\nYear: 2015\n\nAbstract: We present a system that enables m-commerce interactions with roadside billboards, featuring augmented reality enhancements over the video captured by smart mobile devices. The system comprises a mobile application that reads 2D codes placed along with the advertising imagery to recognize the ads and deliver some local interactions, plus a cloud computing environment that assembles tailor-made interactive spots presenting product offers and allowing to put orders, ask for directions, etc. Early validation experiments are reported that reveal positive reception of the concept among different end-users.","Title: Proactive Discovery And Management Of Ride-Sharing Opportunities In Smart Vehicular Ad-Hoc Networks\nYear: 2016\n\nAbstract: Ride-sharing promotes a way to better use empty seats in vehicles, thus saving expenses and reducing emissions of greenhouse gases. In most of the current ride-sharing portals over the Internet the users must explicitly enter information about origin, destination, route, time and date when searching for riders who fulfill their mobility needs. In this paper, we explore new opportunities of ride-sharing to proactively discover the most frequent trips of each user and automatically selecting trip mates for each itinerary. To this aim, we exploit the large number of people who gather together in heavily trafficked zones at certain times to deploy a smart Vehicular Ad-Hoc Network (VANET) over their handheld devices. The smart VANET exchanges among the vehicles the information necessary for (i) matching the users' itineraries and particular preferences, and (ii) identifying like-minded riders for common routes. The approach has been validated by a VANET simulator and a prototype that was used by 46 users.","Title: OPPIA: A Context-Aware Ubiquitous Learning Platform to Exploit Short-Lived Student Networks for Collaborative Learning.\nYear: 2016\n\nAbstract: We present the OPPIA platform, a ubiquitous and smart learning environment, that deploys sporadic learning networks (SLNs) among people (students, teachers and experts) who happen to be in a common place or in a remote place but connected to the platform through the Internet. The idea is to establish dynamic learning networks that encourage their members to work together and create a learning environment with proper resources and activities to satisfy their learning needs. This paper describes the design of the platform from the lowest levels of establishing connections among members of the SLNs, up to the highest level of smart learning services.","Title: A semantics-based exploratory game to enrich school classes with relevant historical facts\nYear: 2016\n\nAbstract: The teaching of History in primary and secondary education often attains low levels of learning and understanding. Building on the success of previous experiences in the area of serious games, we are investigating the potential of situational curiosity and serendipity to increase the retention of historical facts. We present a game designed to explore networks of relationships among the topics of upcoming classes (not necessarily History ones) and topics that may be of interest to their students in a given place and/or on a given date. The design of the game's concept is supported by an intelligent system that uses DBpedia and YAGO as the main sources of knowledge in the search for semantic links among concepts. The teachers are given tools to revise the meshes of concepts and relationships, to modify things and to introduce new relationships.","Title: Developing Quiz Games Linked to Networks of Semantic Connections Among Cultural Venues.\nYear: 2017\n\nAbstract: Existing general-purpose and domain-specific resources of the Semantic Web provide the foundations to discover connections between any two concepts of interest. The EU project CROSSCULT seeks to exploit that possibility in order to spur a change in the way citizens appraise history and culture, by means of web and mobile apps that will let them explore cross-border interconnections among cultural venues and their collections of heritage items. In this paper, we present a tool for experts to collaboratively develop the networks of semantic associations that will drive the gameplay or the storytelling of the apps. This tool includes reasoning aids to discover associations, to identify the most relevant ones in relation to selected topics, and to develop quiz tests involving the chosen entities (heritage items, characters, events or locations).","Title: Deep Guessing: Generating Meaningful Personalized Quizzes on Historical Topics by Introducing Wikicategories in Doc2Vec\nYear: 2018\n\nAbstract: Neural language models are being increasingly used for unsupervised text classification and clustering tasks, with proposals that learn vector representations from word- to document-level. We have adapted one of the latter to discover Wikipedia articles which are relevant to selected historical topics, and also to a given question and its correct answer, by exploiting not only the knowledge captured in the writing of the articles themselves, but also in their classification in wikicategories. Our goal is to automate the generation of personalized multiple-choice quizzes, with wrong alternatives to the correct answer tailored to the level of knowledge of the target user on the selected topics. The approach is shown to provide diverse and meaningful alternatives, in a way that even the absurd ones - which are included mainly for fun-do have some interesting connections to the right answers.","Title: Intersection Intelligence: Supporting Urban Platooning with Virtual Traffic Lights over Virtualized Intersection-Based Routing.\nYear: 2018\n\nAbstract: The advent of the autonomous car is paving the road to the realization of ideas that will help optimize traffic flows, increase safety and reduce fuel consumption, among other advantages. We present one proposal to bring together Virtual Traffics Lights (VTLs) and platooning in urban scenarios, leaning on vehicle-to-vehicle (V2V) communication protocols that turn intersections into virtual containers of data. Newly-introduced protocols for the combined management of VTLs and platoons are validated by simulation, comparing a range of routing protocols for the vehicular networks with the baseline given by common deployments of traditional traffic lights ruled by state-of-the-art policies. The simulation results show that the combination of VTLs and platoons can achieve significant reductions in travel times and fuel consumption, provided that proper algorithms are used to handle the V2V communications.","Title: Experiences from placing Stack Overflow at the core of an intermediate programming course.\nYear: 2019\n\nAbstract: Objectivist methodologies do not align well the learning requirements of modern-day computer science and software engineering, and major universities are moving from the old standards towards learning by doing approaches. We discuss the redesign of an intermediate Computer Programming course taught at the University of Vigo (Spain), seeking to promote question-and-answer websites for programmers as the main source of reference for the students, and turning the teacher into a permanent observer who delivers pertinent advice. The change of programming language, from Java to JavaScript, is also justified. A comparative experiment was conducted with 126 undergraduate students in Vigo (Spain) and Cuenca (Ecuador), revealing advantages in terms of understanding (22% increase in comprehension of new programming constructs), problem-solving capabilities (16% improvement in correct operation of the developed systems) and even greater clarity in communication and documentation (53% better), along with positive perceptions by the students (19% increase)."],"string":"[\n \"Title: Enhancing Residential Gateways: A Semantic OSGi Platform\\nYear: 2008\\n\\nAbstract: The OSGi service platform specification is the most widely adopted solution to the technological problem of building residential gateways. As in many service-oriented architectures, a service registry supports the OSGi framework by facilitating the interaction between clients and services. However, this framework has two main drawbacks. First, service discovery is based on syntactic match making, which obliges the potential client to know the concrete interface of the service it demands. Second, service invocation assumes prior knowledge of the service signatures. Both are significant obstacles in a pervasive environment such as a smart home. A semantic OSGi platform addresses this problem through a service registry that supports applying semantic reasoning to discovery and automate invocation.\",\n \"Title: Downsizing Semantic Reasoning to Fixed and Mobile DTV Receivers.\\nYear: 2007\\n\\nAbstract: Semantic reasoning is being increasingly applied in Dig- ital TV as a means to provide personalized information ser- vices. The pioneering initiatives have opted to place the personalization engines in the service providers' side, be- cause the semantic mechanisms exceed --by far-- the com- putational power of DTV receivers. Unfortunately, this ap- proach has the drawback that it can expose data about the users' interests and preferences to commercial entities, rais- ing severe legal and ethical obstacles. Moreover, in a do- main where most of the information is transmitted through broadcast, there are many cases of intermittent, sporadic or null access to a return channel, which make the personal- ization features unavailable if lodged remotely. With these problems in mind, this paper introduces an architectural ap- proach to deliver personalized DTV services, downsizing a semantic reasoning process to match the capabilities of fixed and mobile receivers. Preliminary experiments are re- ported, showing up to what point the enhanced privacy and availability impinge on personalization quality.\",\n \"Title: Exploiting synergies between semantic reasoning and personalization strategies in intelligent recommender systems: A case study\\nYear: 2008\\n\\nAbstract: Current recommender systems attempt to identify appealing items for a user by applying syntactic matching techniques, which suffer from significant limitations that reduce the quality of the offered suggestions. To overcome this drawback, we have developed a domain-independent personalization strategy that borrows reasoning techniques from the Semantic Web, elaborating recommendations based on the semantic relationships inferred between the user's preferences and the available items. Our reasoning-based approach improves the quality of the suggestions offered by the current personalization approaches, and greatly reduces their most severe limitations. To validate these claims, we have carried out a case study in the Digital TV field, in which our strategy selects TV programs interesting for the viewers from among the myriad of contents available in the digital streams. Our experimental evaluation compares the traditional approaches with our proposal in terms of both the number of TV programs suggested, and the users' perception of the recommendations. Finally, we discuss concerns related to computational feasibility and scalability of our approach.\",\n \"Title: Semantic inference of user's reputation and expertise to improve collaborative recommendations\\nYear: 2012\\n\\nAbstract: Collaborative recommender systems select potentially interesting items for each user based on the preferences of like-minded individuals. Particularly, e-commerce has become a major domain in these research field due to its business interest, since identifying the products the users may like or find useful can boost consumption. During the last years, a great number of works in the literature have focused in the improvement of these tools. Expertise, trust and reputation models are incorporated in collaborative recommender systems to increase their accuracy and reliability. However, current approaches require extra data from the users that is not often available. In this paper, we present two contributions that apply a semantic approach to improve recommendation results transparently to the users. On the one hand, we automatically build implicit trust networks in order to incorporate trust and reputation in the selection of the set of like-minded users that will drive the recommendation. On the other hand, we propose a measure of practical expertise by exploiting the data available in any e-commerce recommender system - the consumption histories of the users.\",\n \"Title: A Technological Framework for TV-Supported Collaborative Learning\\nYear: 2004\\n\\nAbstract: Interactive Digital TV is emerging as a potentially important medium to create opportunities for learning at home. To date, the offer has been mostly based on the contents available through broadcast, but this is expected to change in the near future. The increasing availability of high-quality bidirectional networks, together with the fact that IDTV users are abandoning their passive habits, envisages a new range of highly interactive services that may enhance greatly the prospects of distance education. This paper introduces a technological framework for the development and deployment of distributed and collaborative educational services for IDTV, proposing an extension to the Multimedia Home Platform standard. The framework is based on a selection of freely available technologies, which we integrate into a CASE tool that bridges the gap between course-authoring and programming tasks. We also discuss the possible market implications of our approach, because the ideas presented here contribute to openness in the field of IDTV services, so far monopolised by mainstream broadcasters.\",\n \"Title: Incentivized provision of metadata, semantic reasoning and time-driven filtering: Making a puzzle of personalized e-commerce\\nYear: 2010\\n\\nAbstract: e-Commerce recommender systems select potentially interesting products for users by looking at their purchase histories and preferences. In order to compare the available products against those included in the user's profile, semantics-based recommendation strategies consider metadata annotations that describe their main attributes. Besides, to ensure successful suggestions of products, these strategies adapt the recommendations as the user's preferences evolve over time. Traditional approaches face two limitations related to the aforementioned features. First, product providers are not typically willing to take on the tedious task of annotating accurately a huge diversity of commercial items, thus leading to a substantial impoverishment of the personalization quality. Second, the adaptation process of the recommendations misses the time elapsed since the user has bought an item, which is an essential parameter that affects differently to each purchased product. This results in some pointless recommendations, e.g. including regularly items that the users are only willing to buy sporadically. In order to fight both limitations, we propose a personalized e-commerce system with two main features. On the one hand, we incentivize the users to provide high-quality metadata for commercial products; on the other, we explore a strategy that offers time-aware recommendations by combining semantic reasoning about these annotations with item-specific time functions. The synergetic effects derived from this combination lead to suggestions adapted to the particular needs of the users at any time. This approach has been experimentally validated with a set of users who accessed our personalized e-commerce system through a range of fixed and handheld consumer devices.\",\n \"Title: Semantic Query Validation in Guided-Based Systems: Assuring the Construction of Queries that Make Sense\\nYear: 2010\\n\\nAbstract: Semantic search importance is growing each day as millions of people around the world need to obtain objective and concrete information. Guided-based systems are an alternative to natural language systems regarding the query construction method. However, current guided-based systems perform query validation only at a syntactical level. In this paper we address the semantic validation of queries in order to avoid redundancy and incoherency, therefore preventing the formulation of queries that do not make sense.\",\n \"Title: Enhancing TV programmes with additional contents using MPEG-7 segmentation information\\nYear: 2010\\n\\nAbstract: Interactive Digital TV offers a large amount of TV channels, as well as new contents that come along with the TV programmes. To take advantage of these additional contents and make them easily available to viewers, this paper proposes to offer additional contents linked to the segments of TV programmes by means of semantic relations obtained using MPEG-7 segmentation information. As a practical use of this work, we propose two different application fields: t-learning, with the aim of using TV programmes to engage viewers in education; and personalised advertising, whose goal is offering viewers products of their interest, maximising its effectiveness.\",\n \"Title: Multi-valued model checking in dense-time\\nYear: 2005\\n\\nAbstract: In this paper we introduce $\\\\mathcal{X}$TCTL, a dense-time extension of the multi-valued Computation Tree Logic ($\\\\mathcal{X}$CTL) in [1]. Alternatively, $\\\\mathcal{X}$TCTL is a multi-valued extension of TCTL [2] over quasi-boolean algebras. A multi-valued quotient is defined which enables to reduce dense-time $\\\\mathcal{X}$TCTL model checking to the untimed case.\",\n \"Title: KEPPAN: Knowledge exploitation for proactively-planned ad-hoc networks\\nYear: 2009\\n\\nAbstract: This paper explores the idea of managing mobile ad-hoc networks (MANETs) by the communication needs of their nodes, as a means to facilitate the operation of distributed applications. Specifically, we present a middleware layer that enables reasoning about the multiple possibilities there may exist to ensure satisfiability of certain communication needs. This middleware has been explicitly devised to handle partial and changeable knowledge about the networks, and to guide the search for missing information whenever it cannot conclude whether it will be possible to satisfy some needs. These features provide the basis to implement policies with which to coordinate activities in a MANET, in quest for the configuration that best satisfies the communication needs of its nodes. We provide simulation results to show the comparative advantages of our solution, plus a report of experiments to assess its practicality and usability.\",\n \"Title: Personalizing e-Commerce by Semantics-Enhanced Strategies and Time-Aware Recommendations.\\nYear: 2008\\n\\nAbstract: Current e-commerce recommender systems adapt the selection of commercial items suggested to the users as their preferences evolve over time. However, this adaptation process misses the time elapsed since the user has bought an item, which is an essential parameter that affects differently to each purchased product. This results in some useless recommendations, including regularly items that the users are only willing to buy sporadically. In this paper, we explore a new recommendation strategy that offers time-aware suggestions to e-commerce users, by enhancing reasoning techniques from the Semantic Web with item-dependent time functions. This combination leads to suggestions adapted to the particular needs of each user at any given moment.\",\n \"Title: REENACT: A step forward in immersive learning about Human History by augmented reality, role playing and social networking.\\nYear: 2014\\n\\nAbstract: •A technology-driven edutainment approach for immersive group learning about History.•Use of handheld devices, social networks, role playing, AR and multimedia contents.•Good results in Quality of Service (QoS), Community (QoC) and Experience (QoE).\",\n \"Title: Leveraging Short-Lived Social Networks in Museums to Engage People in History Learning\\nYear: 2013\\n\\nAbstract: The interactions enabled by the popular sites of the Web 2.0 are largely confined to the virtual world of the Internet, thus failing to engage people in relevant interactions with people, contents or resources in their physical environment. In this paper, we motivate the potential of automatically establishing sporadic social networks among people (acquaintances or strangers) who happen to be physically close to one another at a certain moment. We present the design of one platform intended to provide solutions from the lowest level of establishing ad-hoc connections among nearby mobile devices, up to the highest level of automatically identifying the most relevant pieces of information to deliver at any time. One specific scenario is discussed for museum environments, considering the possibility of engaging groups of people into immersive collective experiences to learn about major historical events.\",\n \"Title: AVATAR: A Multi-Agent TV Recommender System using MHP Applications\\nYear: 2005\\n\\nAbstract: In this paper we present AVATAR, a recommender of personalized TV contents, for which an open multi-agent architecture is proposed. This tool uses different knowledge inference strategies, even though we focus on the description of one of them, the naive Bayesian classifiers. Standardization is a key issue to achieve wide deployment in this kind of systems. So, the described recommendation tool has been conceived as an application conforming to Multimedia Home Platform (MHP) standard, to be distributed in the broadcast transport stream that will be tuned by each user's receiver. Also, the TV-Anytime specification has been used referred to the description of contents, the users preferences and their activity logs.\",\n \"Title: An MHP framework to provide intelligent personalized recommendations about digital TV contents\\nYear: 2008\\n\\nAbstract: Digital Television will bring a significant increase in the amount of channels and programs available to end users, with many more difficulties to find contents appealing to them among a myriad of irrelevant information. Thus, automatic content recommenders should receive special attention in the following years to improve their assistance to users. The current content recommenders have important deficiencies that hamper their wide acceptance. In this paper, we present a new approach for automatic content recommendation that significantly reduces those deficiencies. This approach, based on Semantic Web technologies, has been implemented in the AdVAnced Telematic search of Audiovisual contents by semantic Reasoning tool, a hybrid content recommender that makes extensive use of well-known standards, such as Multimedia Home Platform, TV-Anytime and OWL. Also, we have carried out an experimental evaluation, the results of which show that our proposal performs better than other existing approaches. Copyright © 2007 John Wiley & Sons, Ltd.\",\n \"Title: Exploring synergies between content-based filtering and Spreading Activation techniques in knowledge-based recommender systems.\\nYear: 2011\\n\\nAbstract: Recommender systems fight information overload by selecting automatically items that match the personal preferences of each user. The so-called content-based recommenders suggest items similar to those the user liked in the past, using syntactic matching mechanisms. The rigid nature of such mechanisms leads to recommending only items that bear strong resemblance to those the user already knows. Traditional collaborative approaches face up to overspecialization by considering the preferences of other users, which causes other severe limitations. In this paper, we avoid the intrinsic pitfalls of collaborative solutions and diversify the recommendations by reasoning about the semantics of the user’s preferences. Specifically, we present a novel content-based recommendation strategy that resorts to semantic reasoning mechanisms adopted in the Semantic Web, such as Spreading Activation techniques and semantic associations. We have adopted these mechanisms to fulfill the personalization requirements of recommender systems, enabling to discover extra knowledge about the user’s preferences and leading to more accurate and diverse suggestions. Our approach is generic enough to be used in a wide variety of domains and recommender systems. The proposal has been preliminary evaluated by statistics-driven tests involving real users in the recommendation of Digital TV contents. The results reveal the users’ satisfaction regarding the accuracy and diversity of the reasoning-driven content-based recommendations.\",\n \"Title: The multimedia home platform (MHP) framework for web access through digital TV\\nYear: 2003\\n\\nAbstract: The DVB Consortium has recently published the MHP standard to regulate the execution of interactive applications in digital TV, including an Internet profile for web access. In this communication, that profile is analysed.\",\n \"Title: User-generated contents and reasoning-based personalization: Ingredients for a novel model of mobile TV\\nYear: 2011\\n\\nAbstract: During the last years, we have witnessed the boom of the digital market due to the proliferation of emergent audiovisual services and the increasing number of broadband networks. In this scenario, users insistently demand innovative services for exchanging and sharing their own audiovisual contents. In order to meet these needs, in this paper we propose a system that broadcasts user-generated audiovisual contents for handheld devices in a mobile network based on the DVB-H broadcasting standard. Besides, our system offers diverse added-value services to these new active users, such as: (i) multi modal access (via Web or by client applications running locally in handheld devices) to digital contents, (ii) exploitation of return channels to transmit interactive contents that enhance the user's experience, and (iii) annotation, sharing and personalized distribution of audiovisual contents. To achieve these goals, our system adopts well-known technologies for broadcasting and semantic annotation of audiovisual contents, as well as emergent technology from the so-called Web 2.0. A prototype of our system has been experimentally evaluated with a group of students from the University of Vigo, who were enthusiastic about the personalization capabilities offered by our TV system for a mobile setting.\",\n \"Title: A Core of Standards to Support T-learning\\nYear: 2006\\n\\nAbstract: The possibility of transmitting interactive applications along with the audiovisual contents will turn the television into a universal platform to access the Information Society. Nowadays, there is growing interest in exploiting that potential to develop distance learning policies, to supplement the facilities offered by the current e-learning technologies. This short paper describes the implementation of a software module that enables the provision of educational services over Interactive Digital TV (t-learning). This module has been designed according to the technical peculiarities of an IDTV receiver, and resorts to existing standards to favor the convergence of all distance learning mediums.\",\n \"Title: Provision of distance learning services over Interactive Digital TV with MHP\\nYear: 2008\\n\\nAbstract: E-learning technologies have developed greatly in recent years, with considerable success. However, there is increasing evidence that web-based learning is not reaching the social sectors which are more reluctant to contact with the new technologies, thus leading to inequalities in the access to education and knowledge in the Information Society. By hiding the intricacies of computers behind the familiarity of household equipment, Interactive Digital TV (IDTV) is considered to play a key role in addressing this problem, and the term t-learning has been recently coined to mean TV-based interactive learning. Despite several approaches to t-learning have been proposed, works are missing that conceive it as a whole, delimit its scope in comparison with web-based learning and analyze the influence of the normalization of IDTV as a services platform. This paper addresses these issues, and introduces a framework for the development and deployment of t-learning services that promotes interoperability and reuse while taking into account the characteristic features of the IDTV medium.\",\n \"Title: Improving e-Commerce Collaborative Recommendations by Semantic Inference of Neighbors' Practical Expertise.\\nYear: 2011\\n\\nAbstract: E-commerce has become a major application domain for recommender systems due to its business interest. These tools aim to identify the products each user may like or find useful, which can boost users' consumption. Particularly, collaborative recommender systems rely on a set of like-minded users to select the products to offer. Taking into account the expertise of the users who drive such decision can increase the accuracy of the process. However, current approaches require extra data, that is not often available, to obtain expertise measures. In this paper, we apply a semantic approach to get a measure of practical expertise by exploiting the data available in any e-commerce recommender system-the consumption histories of the users. This way, we improve recommendation results transparently to the users.\",\n \"Title: Semantic Reasoning and Mashups: An Innovative Approach to Personalized E-Commerce in Digital TV.\\nYear: 2009\\n\\nAbstract: The potential of Digital TV for e-commerce remains heavily underexploited, mainly because there are no systematic approaches to the provision of applications to browse information about the advertised items, to purchase them online, etc. We present a procedure to automatically compose interactive applications that provide personalized commercial functionalities to the users, gathering contents from multiple sources and with a back-end of semantic web services. The procedure is driven SWRL rules and similarity metrics based on semantic reasoning.\",\n \"Title: AVATAR: an approach based on semantic reasoning to recommend personalized TV programs\\nYear: 2005\\n\\nAbstract: In this paper a TV recommender system called AVATAR (AdVAnce Telematic search of Audiovisual contents by semantic Reasoning) is presented. This tool uses the experience gained in the field of the Semantic Web to personalize the TV programs shown to the end users. The main contribution of our system is a process of semantic reasoning carried out on the descriptions of the TV contents ---provided by means of metainformation--- and on the viewer preferences --- contained in personal profiles. Such process allows to diversify the offered suggestions maintaining the personalization, given that the aim is to find contents appealing for the users, which are related semantically to their programs of interest.Here the framework proposed for this reasoning is introduced, by including (i) the OWL ontology chosen to represent the knowledge of our application domain, (ii) the organization of the user profiles, (iii) the query language LIKO, which is intended to browse the ontology and (iv) the semantic relations inferred from the system knowledge base.\",\n \"Title: Tracing integration analysis in component-based formal specifications\\nYear: 2005\\n\\nAbstract: The correctness of a component-based specification is not guaranteed by the correctness of its components alone; on the contrary, integration analysis is needed to observe their conjoint behavior. Existing approaches often leave the results of the analysis at the level of the integrated system, without tracing them onto the corresponding components. This effectively results in loss of architecture, as it is no longer possible to reason over those components and evolve their specification while keeping the results of integration analysis. This paper presents a formal approach to automatically translate changes on the integrated system into revisions of the components and the architecture initially defined by the developers. Several architectural alternatives are provided that, besides allowing developers to reason about the system from different points of view, promote its correct modularization in two overlapping perspectives: the encapsulation of crosscutting concerns and the elaboration of the architecture desired for the final implementation.\",\n \"Title: ATLAS: a framework to provide multiuser and distributed t-learning services over MHP\\nYear: 2006\\n\\nAbstract: The increasing need of the developed countries to carry out effective distance learning strategies has led to a great development of Internet-based learning technologies (e-learning). Despite its evident advantages, the expansion of e-learning has been limited by the difficulty in reaching important social sectors, and also by the absence of mechanisms to fight the feeling of isolation of the users, which often leads them to abandoning the distance learning activities. This paper tackles these problems by introducing ATLAS, a framework for the development and deployment of multiuser t-learning services (i.e. learning services over Interactive Digital TV). This framework is built around three major features: an architecture for the services that exploits the multimedia capabilities of the television, a communications infrastructure that promotes the establishment of virtual learning communities, and a development tool that allows services to be created with minimum programming knowledge. ATLAS has been designed by considering several features that make Interactive Digital TV quite different from the PC, advising against the direct translation of the models developed for the Internet. In particular, ATLAS adheres to the Multimedia Home Platform (MHP) standard, which is gaining worldwide acceptance as one of the technical solutions that will shape the future of Interactive Digital TV. Copyright © 2006 John Wiley & Sons, Ltd.\",\n \"Title: Methodologies to evolve formal specifications through refinement and retrenchment in an analysis–revision cycle\\nYear: 2009\\n\\nAbstract: The development of requirement specifications is done by accumulating knowledge about the desired systems in a progressive manner. This process can be supported by an analysis–revision cycle, in which the analysis phase checks the correctness of a given specification, and the revision phase modifies it, in case some problems are detected. To date, the analysis and revision activities have been typically considered in isolation, resulting in ineffective support to the stakeholders’ work. In response to that, this article introduces methodologies to conduct an interactive and integrated approach, grounded on the formalization of two basic types of evolutions (refinements and retrenchments) over multi-valued specification and modeling formalisms. Evaluation results are included to show that this approach can indeed help the stakeholders identify and clarify requirements through different stages of development.\",\n \"Title: Automatic Query Generation in Guided Systems: Natural Language Generation from Graphically Built Query\\nYear: 2010\\n\\nAbstract: Guided-based systems are an alternative to natural language systems regarding the query construction method. We present a new solution that bridges the gap between these two types of systems by providing a hybrid interface which combines a graphical query interface for query construction with the correspondent natural language expression automatically generated by the system.\",\n \"Title: An extension to the ADL SCORM standard to support adaptivity: The t-learning case-study\\nYear: 2009\\n\\nAbstract: Current e-learning standards have been designed to provide reusability and interoperability. Besides these features, content personalisation is also necessary, although current standards do not fully support it. In this paper, we study the adaptation possibilities of the SCORM standard and present an extension to permit adaptivity according to user's characteristics. It comprises a syntax for adaptivity rules based on a set of adaptation parameters. The actual values of these adaptation parameters are deduced from the user profile, using inference rules. As a result, adaptive courses are obtained, created with the aim of being personalised before shown to the student.\",\n \"Title: ZapTV: Personalized User-Generated Content for Handheld Devices in DVB-H Mobile Networks\\nYear: 2008\\n\\nAbstract: During the last years, we had witnessed the boom of the digital market due to proliferation of emergent audiovisual services and increasing number of broadband networks. In this scenario, users insistently demand for innovative services for exchanging and sharing their own audiovisual contents and productions. In order to meet these needs, in this paper we propose the ZapTV system. Broadly speaking, this tool broadcasts user-generated audiovisual contents for handheld devices in a mobile network based on the DVB-H broadcasting standard. ZapTV offers diverse added-value services to these new active users, such as: (i) multi modal access (via Web and by handheld devices) to digital contents anywhere and anytime, (ii) availability of a return channel to transmit interactive contents that enhance the user's viewing experience, and (iii) annotation, sharing and personalized distribution of audiovisual contents. To achieve these goals, our system adopts both well-known technologies for broadcasting and semantic annotation of audiovisual contents (such as DVB-H and TV-Anytime), and emergent technology from the so-called Web 2.0, which permit the users to actively cooperate in tasks of generation, annotation and classification of digital contents.\",\n \"Title: REENACT: Augmented reality and collective role playing to enhance the pedagogy of historical events an EXPERIMEDIA experiment\\nYear: 2013\\n\\nAbstract: Much of human history has been shaped by the outcomes of countless battles and wars. Unfortunately, the classical pedagogy of these events merely tells about who were the belligerent forces, how long the fights lasted for, and who ended up winning. We present one proposal to engage groups of people into immersive collective experiences that will make them learn about a certain battle or war both from the inside, as reenactors, and from the outside, as historians. The participants will be equipped with smartphones or tablets that interact with the technological facility developed within the EXPERIMEDIA FP7 project, which provides support for the implementation, deployment and execution of distributed live games, social networking features and augmented reality.\",\n \"Title: Semantic reasoning: a path to new possibilities of personalization\\nYear: 2008\\n\\nAbstract: Recommender systems face up to current information overload by selecting automatically items that match the personal preferences of each user. The so-called content-based recommenders suggest items similar to those the user liked in the past, by resorting to syntactic matching mechanisms. The rigid nature of such mechanisms leads to recommend only items that bear a strong resemblance to those the user already knows. In this paper, we propose a novel content-based strategy that diversifies the offered recommendations by employing reasoning mechanisms borrowed from the SemanticWeb. These mechanisms discover extra knowledge about the user's preferences, thus favoring more accurate and flexible personalization processes. Our approach is generic enough to be used in a wide variety of personalization applications and services, in diverse domains and recommender systems. The proposed reasoning-based strategy has been empirically evaluated with a set of real users. The obtained results evidence computational feasibility and significant increases in recommendation accuracy w.r.t. existing approaches where our reasoning capabilities are disregarded.\",\n \"Title: Guidelines for the incremental identification of aspects in requirements specifications\\nYear: 2006\\n\\nAbstract: The desired principle of separation of concerns in software development can be jeopardized by the so-called crosscutting concerns, which tend to be scattered over (and tangled with) the functionality of the modular units of a system. The correct identification of such concerns (and their encapsulation into separate artifacts) is thereby considered a way to improve software understanding and evolution. Pursuing a proper management of concerns from the requirements engineering stage can greatly benefit the entire software life-cycle. In this paper, we propose conceptual guidelines on how to perform the identification of crosscutting concerns in the process of building requirements specifications. We argue that the identification must be carried out in an incremental way, to encapsulate apart the crosscutting concerns even if they have not emerged completely yet.\",\n \"Title: Application-level assessment of approaches to coordinate node mobility in wireless sensor and actor networks\\nYear: 2010\\n\\nAbstract: Wireless networks of sensor and actor devices require a great deal of coordination to fulfil their objectives. This paper focuses on the dimension of actor-actor coordination, that involves analyzing the data gathered by the sensors and deciding how to act on the environment. Specifically, we tackle the open problem of considering the effects of actors' mobility on the communications needed for coordination. Firstly, we define three general approaches to bring mobility concerns into coordination, adapting solutions from the field of ad-hoc networking. Then, we assess the strengths and weaknesses of the three approaches through simulations of an autonomous robotic system in a representative application scenario, namely the extinction of forest fires. The results reveal trade-offs among performance, delays in communication, sensitiveness to timing and positioning imprecisions, and energy consumption.\",\n \"Title: MHP-OSGi convergence: a new model for open residential gateways\\nYear: 2006\\n\\nAbstract: Nowadays, we are living in a time of important technological changes that affect our lives at home and our communication with the outside world. Among them, the developments in Interactive Digital TV (IDTV) and the smart home field can be considered as particularly important. Related to the former, the new Set-Top Boxes (STBs) are not only a decoder for digital television broadcast but also an entry point to the Information Society and a suitable platform to support the execution of interactive applications. With regards to the latter, the Residential Gateways (RGs) combine different network technologies to allow the connection of different electronics devices and appliances at home, not only with each other but also with the Internet. Since there is no widespread consensus about the configurations and functions of the RGs, we propose to coordinate the two aforementioned worlds by extending the functionality of STBs to become a RG. Our proposal consists of merging the Multimedia Home Platform (MHP), one of the main standard frameworks for IDTV, with Open Service Gateway Initiative (OSGi), the most widely used open platform to set up RGs. To overcome the radically different nature of these specifications—the function-oriented MHP middleware and the service-oriented OSGi framework—we define a new kind of application, coined as XbundLET. This application is able to bridge the gap between the two frameworks and make their interaction feasible. We also show how this proposal has the potential to enable the production of scenarios that cannot currently be put into practice in a natural way. Copyright © 2006 John Wiley & Sons, Ltd.\",\n \"Title: Bringing Content Awareness to Web-Based IDTV Advertising\\nYear: 2012\\n\\nAbstract: In the new technological context of interactive digital (IDTV), traditional TV spots are expected to be replaced by interactive applications. In this paper, we propose a new TV advertising architecture inspired by the philosophy and business models of online advertising. Personalization and content awareness are the two mainstays of our approach that allow advertisers to have more efficient campaigns focused on a targeted audience.\",\n \"Title: Collaborative T-learning: Bringing Greater Levels of Interactivity into the Home\\nYear: 2005\\n\\nAbstract: T-learning -the provision of educational services over Interactive Digital TV-is emerging as a important medium to create opportunities for learning at home. In this paper, we elaborate on a framework for the development and deployment of collaborative t-learning services, presenting an architecture that allows distributing the logic of a service, a way to define complex interaction patterns among users and a network infrastructure that provides adequate support for the communication needs.\",\n \"Title: A semantic approach to avoiding fake neighborhoods in collaborative recommendation of coupons through digital TV\\nYear: 2010\\n\\nAbstract: Consumers are flooded with amounts of discount coupons, oftentimes for products that are far from their interests. This marketing custom is already rising on the Internet and is imminent in Digital TV, where the massive sending of coupons leads to their devaluation and consumer indifference. The computing capabilities of these media permit to alleviate this problem by means of recommender systems, which are very useful tools in application domains that suffer from information overload. However, current recommender systems overlook the diversity of products and services available in the market, which gives rise to forming fake neighborhoods in collaborative filtering strategies. In this paper, we apply semantic reasoning techniques to avoid such fake neighborhoods and, thereby, improve the recommendation process. Furthermore, taking advantage of the Digital TV medium, we propose matching the recommended coupons to TV contents semantically related with them, in order to increase their redemption.\",\n \"Title: T-MAESTRO and its authoring tool: using adaptation to integrate entertainment into personalized t-learning\\nYear: 2008\\n\\nAbstract: Interactive Digital TV opens new learning possibilities where new forms of education are needed. On the one hand, the combination of education and entertainment is essential to boost the participation of viewers in TV learning (t-learning), overcoming their typical passiveness. On the other hand, researchers broadly agree that in order to prevent the learner from abandoning the learning experience, it is necessary to take into account his/her particular needs and preferences by means of a personalized experience. Bearing this in mind, this paper introduces a new approach to the conception of personalized t-learning: edutainment and entercation experiences. These experiences combine TV programs and learning contents in a personalized way, with the aim of using the playful nature of TV to make learning more attractive and to engage TV viewers in learning. This paper brings together our work in constructing edutainment/entercation experiences by relating TV and learning contents. Taking personalization one step further, we propose the adaptation of learning contents by defining A-SCORM (Adaptive-SCORM), an extension of the ADL SCORM standard. Over and above the adaptive add-ons, this paper focuses on two fundamental entities for the proposal: (1) an Intelligent Tutoring System, called T-MAESTRO, which constructs the t-learning experiences by applying semantic knowledge about the t-learners; and (2) the authoring tool which allow teachers to create adaptive courses with a minimal technical background.\",\n \"Title: Avoiding Fake Neighborhoods in e-Commerce Collaborative Recommender Systems: A Semantic Approach.\\nYear: 2009\\n\\nAbstract: Recommender systems are very useful tools inapplication domains that suffer from information overload,offering the users suggestions they may be interested in.Owing to its business interest, e-commerce has become amajor domain in this research field, since identifying thoseproducts that the users will appreciate could increase users’consumption. However, current e-commerce recommendersystems overlook some implications of the great diversity ofproducts and services available in the market, giving rise toform fake neighborhoods in collaborative filtering strategies.In this paper, we propose applying semantic reasoning techniquesto solve this problem, thus improving, qualitativelyand computationally, the recommendation process.\",\n \"Title: A flexible semantic inference methodology to reason about user preferences in knowledge-based recommender systems\\nYear: 2008\\n\\nAbstract: Recommender systems arose with the goal of helping users search in overloaded information domains (like e-commerce, e-learning or Digital TV). These tools automatically select items (commercial products, educational courses, TV programs, etc.) that may be appealing to each user taking into account his/her personal preferences. The personalization strategies used to compare these preferences with the available items suffer from well-known deficiencies that reduce the quality of the recommendations. Most of the limitations arise from using syntactic matching techniques because they miss a lot of useful knowledge during the recommendation process. In this paper, we propose a personalization strategy that overcomes these drawbacks by applying inference techniques borrowed from the Semantic Web. Our approach reasons about the semantics of items and user preferences to discover complex associations between them. These semantic associations provide additional knowledge about the user preferences, and permit the recommender system to compare them with the available items in a more effective way. The proposed strategy is flexible enough to be applied in many recommender systems, regardless of their application domain. Here, we illustrate its use in AVATAR, a tool that selects appealing audiovisual programs from among the myriad available in Digital TV.\",\n \"Title: Receiver-side semantic reasoning for digital TV personalization in the absence of return channels\\nYear: 2009\\n\\nAbstract: Experience has proved that interactive applications delivered through Digital TV must provide personalized information to the viewers in order to be perceived as a valuable service. Due to the limited computational power of DTV receivers (either domestic set-top boxes or mobile devices), most of the existing systems have opted to place the personalization engines in dedicated servers, assuming that a return channel is always available for bidirectional communication. However, in a domain where most of the information is transmitted through broadcast, there are still many cases of intermittent, sporadic or null access to a return channel. In such situations, it is impossible for the servers to learn who is watching TV at the moment, and so the personalization features become unavailable. To solve this problem without sacrificing much personalization quality, this paper introduces solutions to run a downsized semantic reasoning process in the DTV receivers, supported by a pre-selection of material driven by audience stereotypes in the head-end. Evaluation results are presented to prove the feasibility of this approach, and also to assess the quality it achieves in comparison with previous ones.\",\n \"Title: MiSPOT: dynamic product placement for digital TV through MPEG-4 processing and semantic reasoning\\nYear: 2010\\n\\nAbstract: In an increasingly competitive market, stakeholders of the television industry strive to exploit all the possibilities to get revenues from advertising, but their practices are usually at odds with the comfort of the TV viewers. This paper presents the proof of concept of MiSPOT, a system that brings a non-invasive and fully personalized form of advertising to Interactive Digital TV, targeting both domestic and mobile receivers. MiSPOT employs semantic reasoning techniques to select advertisements suited to the preferences, interests and needs of each individual viewer, and then relies on multimedia composition abilities to blend the advertising material with the TV program he/she is viewing at any time. The advertisements can be set to launch interactive commercials, thus enabling means for the provision of t-commerce services. Evaluation experiments are described to show the technical viability of the proposal, and also to gauge the opinions of end users. Questions about the potential impact and exploitation of this new form of advertising are addressed too.\",\n \"Title: A Multi-Agent Open Architecture for a TV Recommender System: A Case Study Using a Bayesian Strategy\\nYear: 2004\\n\\nAbstract: In this paper we present a recommender system of personalized TV contents, called AVATAR1, for which we propose a modular multi-agent architecture, that combines different knowledge inference strategies (such as Bayesian techniques, profiles matching and semantic reasoning). We focus on the description of one of these strategies, the naive Bayesian classifiers, explaining an example in the context of personalized digital television. In order to represent the knowledge in the television domain, we have developed a TV contents ontology, to infer new data from the known information. Besides, the TV-Anytime specification has been used referred to the description of contents and the management of user preferences and their activity logs. The proposed recommender system has been conceived as an application conforming to Multimedia Home Platform (MHP) standard, to be distributed over the broadcast transport stream that will be tuned by the user receiver.\",\n \"Title: Spontaneous interaction with audiovisual contents for personalized e-commerce over Digital TV\\nYear: 2009\\n\\nAbstract: The development of the Interactive Digital TV technologies has the potential to open new possibilities for e-commerce, linked to the broadcasting of audiovisual contents. To cater for the advertising needs, the early initiatives are resorting to the techniques traditionally employed by the television industry, which have proven deficiencies related to targeting and viewers' comfort. In response to that, we have developed a new advertising model, based on identifying products semantically related to the things that draw the viewer's attention on the screen. Thereupon, a personalization engine selects the products which are potentially interesting for the viewer, and assembles interactive services that provide him/her with tailor-made commercial functionalities. This paper provides guidelines on how to support the proposed model over the technological basis of the modern Digital TV receivers (either domestic or mobile ones), and describes a sample scenario of personalized advertising.\",\n \"Title: Incremental specification with SCTL/MUS-T: a case study\\nYear: 2004\\n\\nAbstract: The past decade witnessed a great advance in the field of timed formal methods for the specification and analysis of real-time and safety-critical systems. In this context, timed automata and real-time temporal logics provide a simple, and yet general, way to model and specify the behavior of these systems. At the same time, iterative and incremental development has been massively adopted in professional practice. In order to get closer to this current trend, timed formal methods should be adapted to such lifecycle structures, getting over their traditional role of verifying that a model meets a set of fixed requirements. In the pursuit of this ultimate aim, we propose SCTL/MUS-T, a timed methodology in which many-valuedness let deal with both the uncertainty and the disagreement which are pervasive and desirable in an iterative and incremental process. To illustrate the main ideas behind SCTL/MUS-T methodology this paper focuses on the specification, synthesis and verification of the well known steam-boiler case study.\",\n \"Title: Formal specification applied to multiuser distributed services: experiences in collaborative t-learning\\nYear: 2006\\n\\nAbstract: The development of multiuser and distributed software systems faces the difficulty to program the applications correctly, in a way that guarantees the desired interaction among the users. Motivated by experiences with collaborative t-learning services (i.e. multiuser educational services over Interactive TV), this paper presents a solution to that problem, based on supplementing visual development with formal specification techniques. As a contribution to the development of interactive systems, a software process is introduced that helps defining the separate and the conjoint behavior of different users, incrementally and using highly-accessible formalisms.\",\n \"Title: A Six-valued Logic to Reason about Uncertainty and Inconsistency in Requirements Specifications\\nYear: 2006\\n\\nAbstract: The development of requirements specifications is characterized by the uncertain and changeable knowledge available about the systems to be built. This paper presents a many-valued logic that enables effective reasoning about uncertainty and inconsistency in requirements specifications, motivating the election of six truth values and the definition of a new implication connective. The adequacy of this logic to support a formal development methodology is assessed through a comparison with Belnap's four-valued logic in combination with the classical implications.\",\n \"Title: Making the most of TV on the move: My newschannel\\nYear: 2011\\n\\nAbstract: The increasing success of mobile-TV (m-TV) is changing the habits and customs in TV consumption which now extends to parts of the day when viewers are not at home and, mainly, within short intervals between other daily activities. Since much m-TV consumption will be in spare time, offering the users contents they are interested in becomes extremely important to provide an attractive service which does not discourage potential users. Using DVB-H as transport infrastructure, in this paper we introduce a personalization architecture which perfectly fits in with the value chain of m-TV. By applying semantic models and techniques, personalized virtual channels are dynamically constructed by adequately combining several kinds of contents according to the user's interests. While the personalization architecture is particularized, in this paper, to provide news channels, it could be easily generalized to other fields.\",\n \"Title: Collaborative and role-play strategies in software engineering learning with web 2.0 tools\\nYear: 2014\\n\\nAbstract: Software development processes are inherently complex and require the collaboration and coordination of expert teams. The acquisition of both analysis and design competences as well as social skills should thus be the leitmotiv of courses devoted to software engineering learning. However, these aspects are often ignored and excessive importance is attached to the implementation stage. The learning framework described in this article was designed to teach students these competences and skills by means of an immersive learning experience where, working in a team, each student has to play the role of a software developer and address problems linked to requirements specification, design, and the software development process as a whole. Collaborative strategies of this kind have proven to be very successful in active learning processes, to which we have added continuous assessment mechanisms based on rubrics to provide early feedback to students. Additionally, and taking into account the characteristics of the new European Space for Higher Education, we have designed an online personal learning environment (PLE) that facilitates anytime-anywhere communications and provides a suitable social space for the exchange of information, which is crucial to the success of any teamwork effort. More specifically, we propose a learning activity based on Web 2.0 services and adapted to this particular PLE.(c) 2012 Wiley Periodicals, Inc. Comput Appl Eng Educ 22:658-668, 2014; View this article online at ; DOI\",\n \"Title: An improved virtualization layer to support distribution of multimedia contents in pervasive social applications\\nYear: 2015\\n\\nAbstract: Pervasive social computing is a new paradigm of computer science that aims to facilitate the realization of activities in whichever context, with the aid of information devices and considering social relations between users. This vision requires means to support the shared experiences by harnessing the communication and computing capabilities of the connected devices, relying on direct or hop-by-hop communications among people who happen to be close to each other. In this paper, we present an approach to turn mobile ad-hoc networks (MANETs) into stable communication environments for pervasive social applications. The proposal is based on an evolution of the VNLayer, a virtualization layer that defined procedures for mobile devices to collaboratively emulate an infrastructure of stationary virtual nodes. We refine the VNLayer procedures and introduce new ones to increase the reliability and the responsiveness of the virtual nodes, which serves to boost the performance of routing with a virtualized version of the well-known AODV algorithm. We prove the advantages of the resulting routing scheme by means of simulation experiments and measurements on a real deployment of an application for immersive and collective learning about History in museums and their surroundings.\",\n \"Title: A semantic approach to improve neighborhood formation in collaborative recommender systems\\nYear: 2014\\n\\nAbstract: utomatic recommenders are now omnipresent in e-commerce websites, as selecting and offering to users products they may be interested in can considerably increase sales revenue. The most popular recommendation strategy is currently considered to be the collaborative filtering technique, based on offering to the user who will receive the recommendation items that were appealing to other individuals with similar preferences (the so-called neighbors). On the other hand, its principal obstacle is the sparsity problem, related to the difficulty to find overlappings in ratings when there are many items. As the product catalogue of these sites gets more and more diverse, a new problem has arisen that happens when users share likings for lots of products (for which they are reckoned to be neighbors) but they differ in products similar to the one that is being considered for recommendation. They are fake neighbors. Narrowing the range of products on which similarities between users are sought can help to avoid this, but it usually causes a worsening of the sparsity problem because the chances of finding overlappings gets lower. In this paper, a new strategy is proposed based on semantic reasoning that aims to improve the neighborhood formation in order to overcome the aforementioned fake neighborhood problem. Our approach is aimed at making more flexible the search for semantic similarities between different products, and thus not require users to rate the same products in order to be compared.\",\n \"Title: An Affordable And Inclusive System To Provide Interesting Contents To Dtv Using Recommender Systems\\nYear: 2012\\n\\nAbstract: This paper presents a television scheduling system that aims to aid developing countries in digital television transition by providing content interesting for the people while reducing content acquisition costs. It is based on recommender systems for audiovisual content with special considerations for groups of viewers. The system proposed is fed with content uploaded by the people, properly classified. In a first and basic scenario the system generates four different thematic signals with predefined genres. In the second one, the profile for each user is known and audience is modeled as a group of viewers with known user profiles, allowing its segmentation and channel scheduling according to actual preferences.\",\n \"Title: Optimising Reactive Routing over Virtual Nodes in VANETs\\nYear: 2016\\n\\nAbstract: The Virtual Node Layer (VNLayer) is a clusterbased approach to handle communications in mobile ad-hoc networks (MANETs), furnishing an abstraction of fixed geographical regions served by virtual nodes as a means to tackle the challenges raised by the mobility of the physical nodes. Several studies have proved that the VNLayer constructs can be applied to improve the performance of existing routing algorithms – most notably, AODV– in general MANET scenarios. In this paper, however, we show that the same mechanisms do not work well in the more specific and demanding realm of vehicular ad-hoc networks (VANETs). In response to that, we present several enhancements to the reference implementations of the VNLayer and the adaptation of AODV to work with virtual nodes, proving by means of mathematical analysis and simulation experiments that our solutions achieve better performance in terms of overhead, packet delivery fraction and latencies in VANET scenarios.\",\n \"Title: Augmented reality, smart codes and cloud computing for personalized interactive advertising on billboards\\nYear: 2015\\n\\nAbstract: We present a system that enables m-commerce interactions with roadside billboards, featuring augmented reality enhancements over the video captured by smart mobile devices. The system comprises a mobile application that reads 2D codes placed along with the advertising imagery to recognize the ads and deliver some local interactions, plus a cloud computing environment that assembles tailor-made interactive spots presenting product offers and allowing to put orders, ask for directions, etc. Early validation experiments are reported that reveal positive reception of the concept among different end-users.\",\n \"Title: Proactive Discovery And Management Of Ride-Sharing Opportunities In Smart Vehicular Ad-Hoc Networks\\nYear: 2016\\n\\nAbstract: Ride-sharing promotes a way to better use empty seats in vehicles, thus saving expenses and reducing emissions of greenhouse gases. In most of the current ride-sharing portals over the Internet the users must explicitly enter information about origin, destination, route, time and date when searching for riders who fulfill their mobility needs. In this paper, we explore new opportunities of ride-sharing to proactively discover the most frequent trips of each user and automatically selecting trip mates for each itinerary. To this aim, we exploit the large number of people who gather together in heavily trafficked zones at certain times to deploy a smart Vehicular Ad-Hoc Network (VANET) over their handheld devices. The smart VANET exchanges among the vehicles the information necessary for (i) matching the users' itineraries and particular preferences, and (ii) identifying like-minded riders for common routes. The approach has been validated by a VANET simulator and a prototype that was used by 46 users.\",\n \"Title: OPPIA: A Context-Aware Ubiquitous Learning Platform to Exploit Short-Lived Student Networks for Collaborative Learning.\\nYear: 2016\\n\\nAbstract: We present the OPPIA platform, a ubiquitous and smart learning environment, that deploys sporadic learning networks (SLNs) among people (students, teachers and experts) who happen to be in a common place or in a remote place but connected to the platform through the Internet. The idea is to establish dynamic learning networks that encourage their members to work together and create a learning environment with proper resources and activities to satisfy their learning needs. This paper describes the design of the platform from the lowest levels of establishing connections among members of the SLNs, up to the highest level of smart learning services.\",\n \"Title: A semantics-based exploratory game to enrich school classes with relevant historical facts\\nYear: 2016\\n\\nAbstract: The teaching of History in primary and secondary education often attains low levels of learning and understanding. Building on the success of previous experiences in the area of serious games, we are investigating the potential of situational curiosity and serendipity to increase the retention of historical facts. We present a game designed to explore networks of relationships among the topics of upcoming classes (not necessarily History ones) and topics that may be of interest to their students in a given place and/or on a given date. The design of the game's concept is supported by an intelligent system that uses DBpedia and YAGO as the main sources of knowledge in the search for semantic links among concepts. The teachers are given tools to revise the meshes of concepts and relationships, to modify things and to introduce new relationships.\",\n \"Title: Developing Quiz Games Linked to Networks of Semantic Connections Among Cultural Venues.\\nYear: 2017\\n\\nAbstract: Existing general-purpose and domain-specific resources of the Semantic Web provide the foundations to discover connections between any two concepts of interest. The EU project CROSSCULT seeks to exploit that possibility in order to spur a change in the way citizens appraise history and culture, by means of web and mobile apps that will let them explore cross-border interconnections among cultural venues and their collections of heritage items. In this paper, we present a tool for experts to collaboratively develop the networks of semantic associations that will drive the gameplay or the storytelling of the apps. This tool includes reasoning aids to discover associations, to identify the most relevant ones in relation to selected topics, and to develop quiz tests involving the chosen entities (heritage items, characters, events or locations).\",\n \"Title: Deep Guessing: Generating Meaningful Personalized Quizzes on Historical Topics by Introducing Wikicategories in Doc2Vec\\nYear: 2018\\n\\nAbstract: Neural language models are being increasingly used for unsupervised text classification and clustering tasks, with proposals that learn vector representations from word- to document-level. We have adapted one of the latter to discover Wikipedia articles which are relevant to selected historical topics, and also to a given question and its correct answer, by exploiting not only the knowledge captured in the writing of the articles themselves, but also in their classification in wikicategories. Our goal is to automate the generation of personalized multiple-choice quizzes, with wrong alternatives to the correct answer tailored to the level of knowledge of the target user on the selected topics. The approach is shown to provide diverse and meaningful alternatives, in a way that even the absurd ones - which are included mainly for fun-do have some interesting connections to the right answers.\",\n \"Title: Intersection Intelligence: Supporting Urban Platooning with Virtual Traffic Lights over Virtualized Intersection-Based Routing.\\nYear: 2018\\n\\nAbstract: The advent of the autonomous car is paving the road to the realization of ideas that will help optimize traffic flows, increase safety and reduce fuel consumption, among other advantages. We present one proposal to bring together Virtual Traffics Lights (VTLs) and platooning in urban scenarios, leaning on vehicle-to-vehicle (V2V) communication protocols that turn intersections into virtual containers of data. Newly-introduced protocols for the combined management of VTLs and platoons are validated by simulation, comparing a range of routing protocols for the vehicular networks with the baseline given by common deployments of traditional traffic lights ruled by state-of-the-art policies. The simulation results show that the combination of VTLs and platoons can achieve significant reductions in travel times and fuel consumption, provided that proper algorithms are used to handle the V2V communications.\",\n \"Title: Experiences from placing Stack Overflow at the core of an intermediate programming course.\\nYear: 2019\\n\\nAbstract: Objectivist methodologies do not align well the learning requirements of modern-day computer science and software engineering, and major universities are moving from the old standards towards learning by doing approaches. We discuss the redesign of an intermediate Computer Programming course taught at the University of Vigo (Spain), seeking to promote question-and-answer websites for programmers as the main source of reference for the students, and turning the teacher into a permanent observer who delivers pertinent advice. The change of programming language, from Java to JavaScript, is also justified. A comparative experiment was conducted with 126 undergraduate students in Vigo (Spain) and Cuenca (Ecuador), revealing advantages in terms of understanding (22% increase in comprehension of new programming constructs), problem-solving capabilities (16% improvement in correct operation of the developed systems) and even greater clarity in communication and documentation (53% better), along with positive perceptions by the students (19% increase).\"\n]","isConversational":false},"profile_size":{"kind":"number","value":61,"string":"61"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":72,"string":"72"}}},{"rowIdx":73,"cells":{"question_id":{"kind":"string","value":"Jin Yan"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Novel Heuristic Emergency Path Planning Method Based On Vector Grid Map\" using the following items: emergency path planning, equidistant grid, situational grid, heuristic search, graph acceleration."},"answer":{"kind":"string","value":"Emergency path planning technology is one of the research hotspots of intelligent transportation systems. Due to the complexity of urban road networks and congested road conditions, emergency path planning is very difficult. Road congestion caused by urban emergencies directly affects the original road network structure. In this way, the static weight of the original road network is no longer suitable as the basis for path recommendation. To handle the dynamic situational road network, an equidistant grid emergency path planning framework will be designed. A novel situation grid road network model, based on situation information, is proposed and applied to an equidistant grid emergency path planning framework. A situational grid heuristic search will be proposed methodology based on this model, which can be used to detect the vehicles passing around the congestion area grid and the road to the destination in the shortest time. In the path planning methodology, a grid inspired search strategy based on quaternion function is included, which can make the algorithm converge to the target grid quickly. Three graph acceleration algorithms are proposed to improve the search efficiency of path planning algorithm. Finally, this paper will set up three experiments to verify our proposed method."},"correct_answer":{"kind":"string","value":"Emergency path planning technology is one of the research hotspots of intelligent transportation systems. Due to the complexity of urban road networks and congested road conditions, emergency path planning is very difficult. Road congestion caused by urban emergencies directly affects the original road network structure. In this way, the static weight of the original road network is no longer suitable as the basis for path recommendation. To handle the dynamic situational road network, an equidistant grid emergency path planning framework will be designed. A novel situation grid road network model, based on situation information, is proposed and applied to an equidistant grid emergency path planning framework. A situational grid heuristic search will be proposed methodology based on this model, which can be used to detect the vehicles passing around the congestion area grid and the road to the destination in the shortest time. In the path planning methodology, a grid inspired search strategy based on quaternion function is included, which can make the algorithm converge to the target grid quickly. Three graph acceleration algorithms are proposed to improve the search efficiency of path planning algorithm. Finally, this paper will set up three experiments to verify our proposed method."},"documents":{"kind":"list like","value":["Title: Stiffness analysis and optimization of a novel cable driven anthropomorphic-arm manipulator\nYear: 2012\n\nAbstract: Cartesian stiffness of a 7-DOF(degree-of-freedom) hybrid cable-driven anthropomorphic-arm manipulator(CDAM) was analyzed,in which the shoulder module and wrist module were both 3-DOF cable-driven spherical joint(CDSJ).The calculation process of Cartesian stiffness matrix of the manipulator was demonstrated in detail through the analysis of the stiffness of CDSJ combined with the solution for the stiffness of serial manipulators.The calculation process could be divided into three steps: firstly,the analysis of CDSJ stiffness was introduced to solve the stiffness of shoulder and wrist;secondly,the stiffness of elbow,a cable-driven revolute joint,was calculated;lastly,by merging the stiffness of the wrist,elbow and shoulder module to the joint stiffness matrix,the modified conservative congruence transformation(CCT) was used to get the solution of Cartesian stiffness matrix of CDAM.Based on the stiffness analysis of CDAM,a stiffness optimal algorithm was proposed to enhance the stiffness in motion.The simulation result proves the effectiveness of the algorithm.","Title: Every 3-connected claw-free Z8-free graph is Hamiltonian\nYear: 2010\n\nAbstract: In this article, we first show that every 3-edge-connected graph with circumference at most 8 is supereulerian, which is then applied to show that a 3-connected claw-free graph without Z8 as an induced subgraph is Hamiltonian, where Z8 denotes the graph derived from identifying one end vertex of P9 (a path with 9 vertices) with one vertex of a triangle. The above two results are both best possible in a sense that the number 8 cannot be replaced by 9 and they also extend former results by Brousek et al. in (Discrete Math 196 (1999), 29–50) and by Łuczak and Pfender in (J Graph Theory 47 (2004), 111–121). © 2009 Wiley Periodicals, Inc. J Graph Theory 64: 1–11, 2010","Title: Pseudo-Coloring Occlusion Culling\nYear: 2012\n\nAbstract: A novel algorithm called Pseudo-Coloring Occlusion Culling (PCOC) approach was proposed for complicated models and integrated with an open source 3D graphics engine. In the PCOC, a complicated model was tessellated to a simplified model and the simplified model was rendered to a texture with pseudo-colors in real-time. Then, according to the pseudo-coloring texture, the visibility parts of the complicated model were determined automatically. In this paper, the efficient real-time pseudo-coloring method was applied in an automobile display system. The result indicated that the pseudo-coloiing algorithm reduced 45% invisible triangles, increased 63% of frame rate and improved the performance of real-time rendering.","Title: Rimless wheel with radially expanding spokes: dynamics, impact, and stable gait\nYear: 2004\n\nAbstract: This paper describes the dynamics and intermittent impact model of a novel rimless wheel with radially expanding spokes confined to move in a vertical plane. The wheel has two degrees of freedom, namely rotation in the plane and change of radius. The system has intermittent impacts with the ground and its mathematical model is discontinuous. The motions of the wheel on a horizontal and an inclined plane are investigated. The contact point of the wheel with the ground is assumed to have no slip. We derive the equations of motion in between the collisions and velocity change before and after the wheel impact. We construct the return map of its cyclic motion and plan the motion in between impacts to obtain a stable gait. Dynamic simulations are performed using MATLAB and are presented in the paper.","Title: An improved lower bound for a bi-criteria scheduling problem\nYear: 2008\n\nAbstract: For the bi-criteria scheduling problem of minimizing the sum of completion times and the sum of weighted completion times, min-sum of weighted completion times, we prove that there exists no constant @b1 such that (1+1/@c,@b)-approximate schedules can be found for any @c0. This result confirms a recently published conjecture.","Title: Research on Automatic Large Scale Terrain Modeling.\nYear: 2012\n\nAbstract: As manual interventions in conventional large scale terrain modeling process results in low efficiency, this paper proposes an automatic terrain modeling method (ATMM) aiming to reconstruct terrain meshes taking advantage of remote sensing images with few manual interventions. The modeling method includes acquiring and processing digital elevation model (DEM), establishing topological relations between spatial points and interpolating elevation. Definitions and basic properties of several existing Delaunay triangulations are discussed and the spatial points' topologies are constructed with the Delaunay triangulation template in Computational Geometry Algorithms Library (CGAL). An algorithm efficiency validation on a terrain with 18750X 18750 points demonstrates the ATMM is acceptably competent for accelerating the speed of terrain modeling procedure.","Title: Intelligent Decoupling Control of Gas Collection Process of Multiple Asymmetric Coke Ovens\nYear: 2009\n\nAbstract: This paper presents a hierarchical intelligent decoupling control method for the gas collection process of three asymmetric coke ovens of an iron and steel company. The process features strong asymmetric coupling, large disturbances, and strong nonlinearity. These characteristics are exploited in the following steps to implement intelligent decoupling control. First, three fuzzy expert controllers and two feedforward controllers stabilize the pressure of each gas collector. Then, the three collectors are divided into two groups based on an analysis of the couplings among them to facilitate decoupling control. An intelligent decoupling control method is used to design intragroup and intergroup decoupling controllers. Finally, expert valve control handles the nonlinearity of butterfly valves, and a multirate sampling strategy further improves the control performance. The results of actual runs show that the system satisfactorily performs the intelligent decoupling control of the gas pressures of the coke ovens, sufficiently suppresses disturbances, and accurately stabilizes the pressures.","Title: On 2-Factors with Chorded Quadrilaterals in Graphs.\nYear: 2011\n\nAbstract: Let k be a positive integer and G a graph with order n >= 4k + 3. It is proved that if the minimum degree sum of any two nonadjacent vertices is at least n + k, then G contains a 2-factor with k + 1 disjoint cycles, C(1,) ..., C(k)+i such that C(i) are chorded quadrilateral for 1 <= i <= k - 1 and the length of C(k) is at most 4.","Title: A 3D model simplification algorithm based on edge-collapse\nYear: 2012\n\nAbstract: In computer graphics, 3D model is often represented by triangle meshes. A complicated scene sometimes consists of considerable meshes, which is very difficult to store, transmit and render. This paper introduces an improved mesh simplification algorithm based on edge-collapse. This algorithm utilizes quadric error metric to compute the vertex significance and control the sequence of edge collapse. The experimental results show that the new algorithm can reserve original shape features at low levels of detail.","Title: Sparse self-calibration by map method for MIMO radar imaging\nYear: 2012\n\nAbstract: Multiple-input multiple-output (MIMO) radar is expected to achieve good inversion performance by utilizing space diversity technology. However, traditional imaging methods often fail owing to the practical constraints that the available transmitters and receivers are very few and the number of snapshots is very limited. More seriously, the unavoidable position errors of the transmitters and the receivers would further deteriorate the imaging results. In this paper, by exploiting the sparse priority of the target, the sparse self-calibration by maximum a posterior probability method (SSC-MAP) is proposed to provide high resolution image and realize accurate position calibration at the same time. Numerical simulations verify the effectiveness of the proposed method.","Title: Braking Process Modeling and Simulation of CRH2 Electric Multiple Unit\nYear: 2012\n\nAbstract: Train braking process was greatly affected by factors such as environment, line condition and train driver operation proficiency. How to establish train braking process model and determine the effective braking control strategy is the foundation of achieving the safe and reliable operation of the train. By taking the CRH2 -300 Electric Multiple Unit(EMU) as an example, based on the train braking process operation characteristics and brake deceleration mode curve, multiple models description method for its braking process have been developed with the data-driven modeling. And the efficiency of model is verified with China train control system level 3(CTCS-3). Simulation results show the established braking process model is suitable not only for the common brake but also has high tracking accuracy for the emergency brake. Furthermore, the model is satisfied with requirement of emergency braking distance that should less than 3700m as well as reduces the energy consumption.","Title: Graph partition into small cliques\nYear: 2014\n\nAbstract: Let s and k be two integers with 0 ¿ s ¿ k and let G be a simple graph of order n . This paper investigates clique partition problems. It is proved that if n ¿ 3 s + 4 ( k - s ) and d ( u ) + d ( v ) ¿ 3 ( n - s ) / 2 + k - 1 for any pair of non-adjacent vertices u , v of G , then G contains s vertex-disjoint K 3 s and k - s vertex-disjoint K 4 s such that all of them are vertex-disjoint. Moreover, the degree condition is sharp.","Title: Neighborhood Unions for the Existence of Disjoint Chorded Cycles in Graphs\nYear: 2013\n\nAbstract: chorded cycle is a cycle with at least one chord. We prove that if G is a simple graph with order n 4 k and $${|N_G(x)\\cup N_G(y)|\\geq 4k+1}$$ for each nonadjacent pair of vertices x and y , then G contains k vertex-disjoint chorded cycles. The degree condition is sharp in general.","Title: Contractible configurations on 3-flows in graphs satisfying the Fan-condition\nYear: 2013\n\nAbstract: Let G be a 2-edge-connected graph of order n such that each pair of vertices x and y at distance 2 satisfies max{d(x),d(y)}n2 (weak Fan-condition, [G.H. Fan, New sufficient conditions for cycles in graphs, J. Combin. Theory Ser. B 37 (1984) 221-227]). It is obtained in this paper that G admits a nowhere-zero 3-flow and is a 3-flow contractible configuration except for a family of well-characterized counterexamples. This result generalizes some earlier results about 3-flows, 3-flow contractible configurations under some degree-sum conditions ([G. Fan, C. Zhou, Ore condition and nowhere-zero 3-flows, SIAM J. Discrete Math. 22 (2008) 288-294], [R. Luo, R. Xu, J.H. Yin, G.X. Yu, Ore-condition and Z\"3-connectivity, European J. Combin. 29 (2008) 1587-1595]).","Title: Vertex-disjoint triangles in K1,t-free graphs with minimum degree at least t\nYear: 2010\n\nAbstract: graph is said to be K\"1\",\"t-free if it does not contain an induced subgraph isomorphic to K\"1\",\"t. Let h(t,k) be the smallest integer m such that every K\"1\",\"t-free graph of order greater than m and with minimum degree at least t contains k vertex-disjoint triangles. In this paper, we obtain a lower bound of h(t,k) by a constructive method. According to the lower bound, we totally disprove the conjecture raised by Hong Wang [H. Wang, Vertex-disjoint triangles in claw-free graphs with minimum degree at least three, Combinatorica 18 (1998) 441-447]. We also obtain an upper bound of h(t,k) which is related to Ramsey numbers R(3,t). In particular, we prove that h(4,k)=9(k-1) and h(5,k)=14(k-1).","Title: Degree conditions for the partition of a graph into triangles and quadrilaterals\nYear: 2010\n\nAbstract: For two positive integers r and s with r >= 2s - 2, if G is a graph of order 3r + 4s such that d(x) + d(y) >= 4r + 4s for every xy is not an element of E(G), then G independently contains r triangles and s quadrilaterals, which partially prove the El-Zahar's Conjecture.","Title: Notes on Hamiltonian Graphs and Hamiltonian-Connected Graphs.\nYear: 2013\n\nAbstract: Let G = (V (G), E(G)) be a graph and alpha(G) be the independence number of G. For a vertex v is an element of V(G), d(v) and N(v) represent the degree and the neighborhood of v in G, respectively. In this paper, we prove that if G is a k-connected(k >= 2) graph of order n, and if max{d(v) : v is an element of S} >= n/2 for every independent set S of G with vertical bar S vertical bar = k which has two distinct vertices x, y is an element of S satisfying 1 <= vertical bar N(x) boolean AND N(y)vertical bar <= alpha(G) - 2, then either G is hamiltonian or else G belongs to one of a family of exceptional graphs. We also give a similar sufficient condition for Hamiltonian-connected graphs.","Title: Adaptive control of uncertain Hammerstein systems with monotonic input nonlinearities using auxiliary nonlinearities\nYear: 2012\n\nAbstract: We extend retrospective cost adaptive control (RCAC) to command following for uncertain Hammerstein systems. We assume that only one Markov parameter of the linear plant is known and that the input nonlinearity is monotonic but otherwise unknown. Auxiliary nonlinearities are used within RCAC to account for the effect of the input nonlinearity.","Title: Automated segmentation of CBCT image using spiral CT atlases and convex optimization.\nYear: 2013\n\nAbstract: Cone-beam computed tomography (CBCT) is an increasingly utilized imaging modality for the diagnosis and treatment planning of the patients with craniomaxillofacial (CMF) deformities. CBCT scans have relatively low cost and low radiation dose in comparison to conventional spiral CT scans. However, a major limitation of CBCT scans is the widespread image artifacts such as noise, beam hardening and inhomogeneity, causing great difficulties for accurate segmentation of bony structures from soft tissues, as well as separating mandible from maxilla. In this paper, we presented a novel fully automated method for CBCT image segmentation. In this method, we first estimated a patient-specific atlas using a sparse label fusion strategy from predefined spiral CT atlases. This patient-specific atlas was then integrated into a convex segmentation framework based on maximum a posteriori probability for accurate segmentation. Finally, the performance of our method was validated via comparisons with manual ground-truth segmentations.","Title: Disjoint triangles and quadrilaterals in a graph\nYear: 2008\n\nAbstract: Let G be a simple graph of order n and s and k be two positive integers. Brandt et al. obtained the following result: If s= =3s+4(k-s) and @s\"2(G)>=n+s, then G contains k disjoint cycles C\"1,...,C\"k satisfying |C\"i|=3 for 1= =3s+4(k-s)+3.","Title: Nowhere-zero 3-flows and Z3-connectivity of a family of graphs\nYear: 2011\n\nAbstract: Tutte conjectured that every 4-edge-connected graph admits a nowhere-zero 3-flow. Jaeger et al. [F. Jaeger, N. Linial, C. Payan, M. Tarsi, Group connectivity of graphs-a nonhomogeneous analogue of Nowhere-zero flow properties, J. Combin. Theory, Ser. B 56 (1992) 165-182] conjectured that every 5-edge-connected graph is Z\\\"3- connected. Let G be a simple connected graph with n vertices. It is proved in this paper that ifd(u)+d(v)=nfor each pair of verticesu,vwith distance two, then (1) Gadmits a nowhere-zero 3-flow if and only ifGis none of 7 excluded graphs; (2) GisZ\\\"3-connected if and only ifGis none of 15 excluded graphs. The first theorem strengthens an early result by Fan et al. [ G. Fan, C. Zhou. Ore condition and Nowhere-zero 3-flows, SIAM J. Discrete Math., 22 (2008) 288-294] and the second theorem strengthens an early result by Luo, et al. [ R. Luo, R. Xu, J.H. Yin, G.X. Yu, Ore-condition and Z\\\"3-connectivity, European J. Combin., 29 (2008) 1587-1595].","Title: Fault detection for aircraft control surfaces using approximate input reconstruction\nYear: 2009\n\nAbstract: We use an approximate input reconstruction algorithm to reconstruct unknown inputs, which are then used as a basis for fault detection. The approximate input reconstruction algorithm is a least squares algorithm that estimates both the unknown initial state and input history. The estimated inputs are then compared to the commanded values and sensor values to assess the health of actuators and sensors. This approach is applied to the longitudinal and lateral dynamics of an aircraft. The input reconstruction algorithm can be used for minimum-phase or nonminimum-phase zeros; however, zeros on the unit circle yield persistent estimation errors and thus poor input reconstruction.","Title: On 2-factors with cycles containing specified edges in a bipartite graph\nYear: 2009\n\nAbstract: Let k>=1 be an integer and G=(V\"1,V\"2;E) a bipartite graph with |V\"1|=|V\"2|=n such that n>=2k+2. In this paper it has been proved that if for each pair of nonadjacent vertices [email protected]?V\"1 and [email protected]?V\"2, d(x)+d(y)>[email protected][email protected]?, then for any k independent edges e\"1,...,e\"k of G, G has a 2-factor with k+1 cycles C\"1,...,C\"k\"+\"1 such that e\"[email protected]?E(C\"i) and |V(C\"i)|=4 for each [email protected]?{1,...,k}. We shall also show that the conditions in this paper are sharp.","Title: Compare and Analysis of Security Strategy in WAP and I-Mode Network\nYear: 2008\n\nAbstract: This paper presents the security strategy used by WAP and I-Mode. It includes security transport protocol, the type of certificate, the performance of gateway, smartcard and authenticate scheme. It will first be illustrated from the architecture, and then discussed application situation. All of these schemes of WAP will be compared with the similar adopted technology of I-Mode. Through comparing, deficiencies of both WAP and I-Mode were uncovered. Methods to resolve these security problems were proposed at the end of this paper. The overall results derived from this work show WAP has more detailed, more general and more secure security scheme than I-Mode.","Title: Real-Time Rendering and Animating of Grass.\nYear: 2012\n\nAbstract: Real-time rendering of grass scenes is challenging for the geometric complexity and great volume of data. In this paper, a combination approach of geometry-based, volume slice-based and image-based techniques for grass rendering is proposed. Different levels of detail (LOD) are sequentially applied depending on the distance between models and camera. Seamless transition between two levels of detail is attained by hybrid models and fade-out method. Grass distribution is managed by density and height map based on geographic information system (GIS) data. In this method, it is possible to effectively conduct the simulation of large-scale grass scenes in real-time. The movement of grass with the wind is considered as a single degree of freedom (SDOF) vibration system. We realize the grass animation with shader in real-time and obtain acceptable results.","Title: On 2-Factors With Quadrilaterals Containing Specified Vertices In A Bipartite Graph\nYear: 2007\n\nAbstract: In this paper we consider the problem as follows: Given a bipartite graph G = (V-1, V-2; E) with vertical bar V-1 vertical bar = vertical bar V-2 vertical bar = n and a positive integer k, what degree condition is sufficient to ensure that for any k distinct vertices v(1), v(2), center dot center dot center dot, v(k) of G, G contains k independent quadrilaterals Q(1), Q(2), center dot center dot center dot, Q(k) such that v(i) is an element of V (Q(i)) for every i is an element of {1, 2, center dot center dot center dot, k}, or G has a 2-factor with k independent cycles of specified lengths with respect to {v(1), v(2), center dot center dot center dot, v(k)}? We will prove that if d(x) + d(y) >= [(4n + k)/3] for each pair of nonadjacent vertices x is an element of V-1 and y is an element of V-2, then, for any k distinct vertices v(1), v(2), center dot center dot center dot, v(k) of G, G contains k independent quadrilaterals Q(1), Q(2), center dot center dot center dot, Q(k) such that v(i) is an element of V(Q(i)) for each i is an element of {1, center dot center dot center dot, k}. Moreover, G has a 2-factor with k cycles with respect to {v(1),v(2), center dot center dot center dot, v(k)} such that k-1 of them are quadrilaterals. We also discuss the degree conditions in the above results.","Title: Palmprint verification based on genetic algorithm\nYear: 2008\n\nAbstract: This paper proposes a novel idea based feature selection in the verification system of palmprint, which can realize the specific feature selection for different user using genetic algorithm (GA). In the stage of enrollment, discrete wavelet transforms (DWT) and statistical methods are first used for feature extraction. Then GA is employed for feature selection, which means that each user has a specific feature index and verification modality. In the stage of verification, according to the feature index, the selected features are input to the related support vector machine (SVM) for classification. We test the proposed method on Hong Kong Polytechnic University Palmprint Database. Through the comparison, the experimental results show that our proposed method is effective and can reach high performance. © 2008 IEEE.","Title: Color degree and heterochromatic paths in edge-colored graphs.\nYear: 2014\n\nAbstract: Let G be an edge-colored graphs. A heterochromatic path of G is such a path in which no two edges have the same color. Let g(c)(G) and d(c)(nu) denote the heterochromatic girth and the color degree of a vertex nu of G, respectively. In this paper, some color degree and heterochromatic girth conditions for the existence of heterochromatic paths are obtained.","Title: Adaptive control of uncertain Hammerstein systems with non-monotonic input nonlinearities using auxiliary nonlinearities\nYear: 2013\n\nAbstract: We extend retrospective cost adaptive control (RCAC) with auxiliary nonlinearities to command following for uncertain Hammerstein systems with non-monotonic input nonlinearities. We assume that only one Markov parameter of the linear plant is known and that the non-monotonic input nonlinearity is uncertain. Auxiliary nonlinearities are used within RCAC to account for the non-monotonic input nonlinearity. The required modeling information for the input nonlinearity includes the intervals of monotonicity as well as values of the nonlinearity that determine overlapping segments of the range of the nonlinearity within each interval of monotonicity.","Title: Estimating anatomically-correct reference model for craniomaxillofacial deformity via sparse representation.\nYear: 2014\n\nAbstract: The success of craniomaxillofacial (CMF) surgery depends not only on the surgical techniques, but also upon an accurate surgical planning. However, surgical planning for CMF surgery is challenging due to the absence of a patient-specific reference model. In this paper, we present a method to automatically estimate an anatomically correct reference shape of jaws for the patient requiring orthognathic surgery, a common type of CMF surgery. We employ the sparse representation technique to represent the normal regions of the patient with respect to the normal subjects. The estimated representation is then used to reconstruct a patient-specific reference model with \"restored\" normal anatomy of the jaws. We validate our method on both synthetic subjects and patients. Experimental results show that our method can effectively reconstruct the normal shape of jaw for patients. Also, a new quantitative measurement is introduced to quantify the CMF deformity and validate the method in a quantitative approach, which is rarely used before.","Title: A three-wheel vehicle with expanding wheels: differential flatness, trajectory planning, and control\nYear: 2003\n\nAbstract: This paper describes the analysis and simulation of a novel 3-wheel vehicle with expanding wheels. The motivation for this design is to attain added navigation capability by expanding the wheels according to the requirements of the terrain. For this vehicle, we present the analysis of motions in the plane and in 3D space. In these models, it is assumed that the contact point of the wheel with the ground is directly underneath the center of the wheel and has no slip. The kinematic models are studied for the property of differential flatness and this property is used to plan the trajectory and design feedback controllers. The paper presents simulations performed using MATLAB. Currently, a vehicle with these features has been fabricated at University of Delaware.","Title: Averaged ratio between complementary profiles for evaluating shape distortions of map projections and spherical hierarchical tessellations\nYear: 2016\n\nAbstract: We describe a metric named averaged ratio between complementary profiles to represent the distortion of map projections, and the shape regularity of spherical cells derived from map projections or non-map-projection methods. The properties and statistical characteristics of our metric are investigated. Our metric (1) is a variable of numerical equivalence to both scale component and angular deformation component of Tissot indicatrix, and avoids the invalidation when using Tissot indicatrix and derived differential calculus for evaluating non-map-projection based tessellations where mathematical formulae do not exist (e.g., direct spherical subdivisions), (2) exhibits simplicity (neither differential nor integral calculus) and uniformity in the form of calculations, (3) requires low computational cost, while maintaining high correlation with the results of differential calculus, (4) is a quasi-invariant under rotations, and (5) reflects the distortions of map projections, distortion of spherical cells, and the associated distortions of texels. As an indicator of quantitative evaluation, we investigated typical spherical tessellation methods, some variants of tessellation methods, and map projections. The tessellation methods we evaluated are based on map projections or direct spherical subdivisions. The evaluation involves commonly used Platonic polyhedrons, Catalan polyhedrons, etc. Quantitative analyses based on our metric of shape regularity and an essential metric of area uniformity implied that (1) Uniform Spherical Grids and its variant show good qualities in both area uniformity and shape regularity, and (2) Crusta, Unicube map, and a variant of Unicube map exhibit fairly acceptable degrees of area uniformity and shape regularity.","Title: Minimum Modelling Retrospective Cost Adaptive Control Of Uncertain Hammerstein Systems Using Auxiliary Nonlinearities\nYear: 2014\n\nAbstract: We augment retrospective cost adaptive control (RCAC) with auxiliary nonlinearities to address a command-following problem for uncertain Hammerstein systems with possibly non-monotonic input nonlinearities. We assume that only one Markov parameter of the linear plant is known and that the input nonlinearity is uncertain. Auxiliary nonlinearities are used within RCAC to create a globally non-decreasing composite input nonlinearity. The required modelling information for the input nonlinearity includes the intervals of monotonicity as well as values of the nonlinearity that determine overlapping segments of the range of the nonlinearity within each interval of monotonicity.","Title: Classification of Alzheimer's Disease Based on Multiple Anatomical Structures' Asymmetric Magnetic Resonance Imaging Feature Selection.\nYear: 2015\n\nAbstract: The quality of magnetic resonance imaging (MRI) features is key to the classification of Alzheimer's disease. However, relevant research has as yet paid little attention to asymmetric MR features. In this paper, the asymmetric MR features of multiple anatomical structures are extracted. The MR feature types include volume feature and several kinds of texture features. Subsequently, the extracted features are selected based on the wrapper feature selection method with chain-like agent genetic algorithm (CAGA) and support vector machine (SVM). Finally, the selected asymmetric MR features are used for classification of Alzheimer's disease. Experimental results show that the extracted features have apparent asymmetrical characteristics. The asymmetric volume feature of single anatomical structure can have better discrimination capability than the whole volume feature of same anatomical structure. Single selected asymmetric MR feature has displayed a superior discrimination capability in regards to three conditions of Alzheimer's disease. The improvement is very apparent compared to before feature selection and the p-value-based feature selection method. In conclusion, this proposed method offer a new kind of feature type and can improve the classification rate for diagnosis of Alzheimer's disease.","Title: Environment Factors Monitoring System Based On Can Bus\nYear: 2016\n\nAbstract: In order to solve the greenhouse environmental factors monitoring system wiring is difficult, high cost, single parameter monitoring, lack of flexibility and scalability, which can't meet the requirements of the modern intelligent greenhouse. In this study, a new remote monitoring system was established. In terms of the hardware, the SCM C8051F040 was adopted to collect the environmental parameters such as temperature, humidity, light intensity, CO2 concentration and so on. All data were uploaded via CAN bus and GPRS to the remote host computer. The collected data would be sent to the relevant agricultural management personnel in real time through the GPRS network so that the management could be carried out. Based on Kingview software platform, which was developed to use graphic language and command language system of the PC. Preliminary experimental results show that the system has the correct data transmission, stable operation, good real-time performance and accurately monitor the environmental factors in the greenhouse. The system has the advantages of flexible networking and strong expansibility and intuitive interface, which can well meet the needs of environmental factors monitoring in greenhouse..","Title: Vertex-disjoint copies of K1, 3 in K1, r-free graphs.\nYear: 2016\n\nAbstract: Abstract A graph G is said to be K 1 , r -free if G does not contain an induced subgraph isomorphic to K 1 , r . Let k , r be integers with k ≥ 2 , r ≥ 4 . In this paper, we prove that if G is a K 1 , r -free graph of order at least ( k − 1 ) ( 3 r − 2 ) + 1 with δ ( G ) ≥ 3 , then G contains k vertex-disjoint copies of K 1 , 3 . This result shows that Fujita’s conjecture (2008) is true for t = 3 and r ≥ 4 .","Title: Efficient Online Surveillance Video Processing Based on Spark Framework.\nYear: 2016\n\nAbstract: In the current surveillance video processing systems, the video processing algorithms and the physical resources are highly coupled, and a video stream is usually used as a basic task scheduling unit. With the expansion of the scale of the system, the traditional systems will cause the large resource fragments that cannot be utilized adequately. In this paper, we propose a novel online surveillance video processing system architecture that combines the distributed Kafka message queue and Spark computing framework. Our system decouples the video stream collection and the video stream processing, and further decouples the video processing tasks and the physical resources. This loosely coupled architecture can quickly recover the failed tasks without data loss for the large-scale video surveillance, and can provide the more scalable distributed computing ability. In addition, a fine-grained online video task management method, which uses the cached video data blocks as the scheduling units, is proposed to increase the resource utilization. Experimental results show that our system has the higher resource utilization and the higher task capacity compared with the traditional systems.","Title: Heterogeneous multimodal biomarkers analysis for Alzheimer's disease via Bayesian network.\nYear: 2016\n\nAbstract: By 2050, it is estimated that the number of worldwide Alzheimer's disease (AD) patients will quadruple from the current number of 36 million, while no proven disease-modifying treatments are available. At present, the underlying disease mechanisms remain under investigation, and recent studies suggest that the disease involves multiple etiological pathways. To better understand the disease and develop treatment strategies, a number of ongoing studies including the Alzheimer's Disease Neuroimaging Initiative (ADNI) enroll many study participants and acquire a large number of biomarkers from various modalities including demographic, genotyping, fluid biomarkers, neuroimaging, neuropsychometric test, and clinical assessments. However, a systematic approach that can integrate all the collected data is lacking. The overarching goal of our study is to use machine learning techniques to understand the relationships among different biomarkers and to establish a system-level model that can better describe the interactions among biomarkers and provide superior diagnostic and prognostic information. In this pilot study, we use Bayesian network (BN) to analyze multimodal data from ADNI, including demographics, volumetric MRI, PET, genotypes, and neuropsychometric measurements and demonstrate our approach to have superior prediction accuracy.","Title: Vertex-Disjoint Cycles Containing Specified Vertices in a Bipartite Graph.\nYear: 2016\n\nAbstract: The theory of vertex-disjoint cycles of a graph is the generalization of the well-known Hamiltonian cycle theory. In this paper, we prove the following result. Let $$G = (V_{1}, V_{2}; E$$G=(V1,V2źE) be a bipartite graph with $$|V_{1}|= |V_{2}|= n$$|V1|=|V2|=n such that $$n\\\\ge 2k + 1$$nź2k+1, where k$$\\\\ge $$ź 1 is an integer. If $$\\\\sigma _{1,1}(G) \\\\ge n + k$$ź1,1(G)źn+k, then for any k distinct vertices $$v_{1}, v_{2}, \\\\ldots , v_{k}$$v1,v2,ź,vk of G, G contains $$k - 1$$k-1 quadrilaterals $$C_{1}, C_{2}, \\\\ldots , C_{k-1}$$C1,C2,ź,Ck-1 and a path $$P_{k}$$Pk of order 2t, where $$t = n - 2(k - 1)$$t=n-2(k-1), such that all of them are vertex-disjoint and $$v_{i} \\\\in V(C_{i})$$viźV(Ci) for each $$i \\\\in \\\\{1, 2, \\\\ldots , k - 1\\\\}, v_{k} \\\\in V(P_{k})$$iź{1,2,ź,k-1},vkźV(Pk). Using this result we also prove that G contains k vertex-disjoint cycles $$C_{1}, C_{2}, \\\\ldots , C_{k}$$C1,C2,ź,Ck such that $$v_{i} \\\\in V(C_{i})$$viźV(Ci) for each $$i \\\\in \\\\{1, 2, \\\\ldots , k\\\\}$$iź{1,2,ź,k} and there are $$k - 1$$k-1 quadrilaterals in $$\\\\{C_{1}, C_{2}, \\\\ldots , C_{k}\\\\}$${C1,C2,ź,Ck}. Moreover, the degree condition is sharp.","Title: Toward a Parallel Turing Machine Model.\nYear: 2016\n\nAbstract: In the field of parallel computing, the late leader Ken Kennedy, has raised a concern in early 1990s: \"Is Parallel Computing Dead?\" Now, we have witnessed the tremendous momentum of the \"second spring\" of parallel computing in recent years. But, what lesson should we learn from the history of parallel computing when we are walking out from the bottom state of the field? To this end, this paper examines the disappointing state of the work in parallel Turing machine models in the past 50 years of parallel computing research. Lacking a solid yet intuitive parallel Turing machine model will continue to be a serious challenge. Our paper presents an attempt to address this challenge - by presenting a proposal of a parallel Turing machine model - the PTM model. We also discuss why we start our work in this paper from a parallel Turing machine model instead of other choices.","Title: Reconstructing tree trunks by 3D bar filters.\nYear: 2017\n\nAbstract: In this work, we propose an new problem to be solved: reconstruct the 3D points cloud of wild forest from 2D images sequences, locate the tree trunk position and estimate the tree trunk diameters from those reconstructed 3D points and we developed an novel method to solve those three problem once which is able to reconstruct the 3D tree trunk structures, locate the tree trunk and estimate the tree trunk diameters. This is the first work trying to solving those problems jointly. The previous work separate those problem as three sub-tasks: Reconstruct the 3D points from images sets using structure from motion techniques, detect the tree trunk locations and diameters by fitting cylinder models. Unfortunately, the first sub-task is extremely hard due to the poor discriminative image features, strong illumination changes, data corruption caused by the shadows and limited camera view inside the wild forest. The second sub-task requires the first sub-task to provide high quality 3D point cloud. In this work, we found that we are able to take advantage of the vertical structures in the forest to obtain more stable feature matching. Furthermore, with those vertical structure we are able to obtain the tree locations and diameters directly in the process of 3D reconstruction. We demonstrated that our method is able to provide a unified frame work for reconstructing the 3D tree models, estimate the location and trunk size using the 2D images sequences or videos taken in the forest.","Title: Parallel Turing Machine, a Proposal.\nYear: 2017\n\nAbstract: We have witnessed the tremendous momentum of the second spring of parallel computing in recent years. But, we should remember the low points of the field more than 20 years ago and review the lesson that has led to the question at that point whether “parallel computing will soon be relegated to the trash heap reserved for promising technologies that never quite make it” in an article entitled “the death of parallel computing” written by the late Ken Kennedy — a prominent leader of parallel computing in the world. Facing the new era of parallel computing, we should learn from the robust history of sequential computation in the past 60 years. We should study the foundation established by the model of Turing machine (1936) and its profound impact in this history. To this end, this paper examines the disappointing state of the work in parallel Turing machine models in the past 50 years of parallel computing research. Lacking a solid yet intuitive parallel Turing machine model will continue to be a serious challenge in the future parallel computing. Our paper presents an attempt to address this challenge by presenting a proposal of a parallel Turing machine model. We also discuss why we start our work in this paper from a parallel Turing machine model instead of other choices.","Title: Partial Degree Conditions and Cycle Coverings in Bipartite Graphs.\nYear: 2017\n\nAbstract: Let k be a positive integer. Let G be a graph of order $$n\\\\ge 3$$n¿3 and W a subset of V(G) with $$|W|\\\\ge 3k$$|W|¿3k. Wang (J Graph Theory 78:295---304, 2015) proved that if $$d(x)\\\\ge 2n/3$$d(x)¿2n/3 for each $$x\\\\in W$$x¿W, then G contains k vertex-disjoint cycles such that each of them contains at least three vertices of W. In this paper, we obtain an analogue result of Wang's Theorem in bipartite graph with the partial degree condition. Let $$G=(V_1,V_2;E)$$G=(V1,V2¿E) be a bipartite graph with $$|V_1|=|V_2|=n$$|V1|=|V2|=n, and let W be a subset of $$V_1$$V1 with $$|W|\\\\ge 2k$$|W|¿2k, where k is a positive integer. We show that if $$d(x)+d(y)\\\\ge n+k$$d(x)+d(y)¿n+k for every pair of nonadjacent vertices $$x\\\\in W, y\\\\in V_2$$x¿W,y¿V2, then G contains k vertex-disjoint cycles such that each of them contains at least two vertices of W.","Title: Disjoint cycles in graphs with distance degree sum conditions.\nYear: 2017\n\nAbstract: In this paper, we prove that for any positive integer k and for any simple graph G of order at least 3k, if d(x)+d(y)≥4k for every pair of vertices x and y of distance 2 in G, then with one exception, G contains k disjoint cycles. This generalizes a former result of Corrádi and Hajnal (1963).","Title: Personalized Diagnosis for Alzheimer's Disease.\nYear: 2017\n\nAbstract: Current learning-based methods for the diagnosis of Alzheimer's Disease (AD) rely on training a general classifier aiming to recognize abnormal structural alternations from homogenously distributed dataset deriving from a large population. However, due to diverse disease pathology, the real imaging data in routine clinic practices is highly complex and heterogeneous. Hence, prototype methods commonly performing well in the laboratory cannot achieve expected outcome when applied under the real clinic setting. To address this issue, herein we propose a novel personalized model for AD diagnosis. We customize a subject-specific AD classifier for the new testing data by iteratively reweighting the training data to reveal the latent testing data distribution and refining the classifier based on the weighted training data. Furthermore, to improve estimation of diagnosis result and clinical scores at the individual level, we extend our personalized AD diagnosis model to a joint classification and regression scenario. Our model shows improved performance on classification and regression accuracy when applied on Magnetic Resonance Imaging (MRI) selected from Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Our work pin-points the clinical potential of personalized diagnosis framework in AD.","Title: Disjoint cycles in directed graphs.\nYear: 2018\n\nAbstract: Let s and t be two non-negative integers and let D be a directed graph of order n >= 3s + 4t + 3. In this paper we will show that if the minimum sum of in-degree and out-degree delta(D) >= (3n - 3)/2, then D contains s +t + 1 disjoint cycles C-1, ... , Cs+t+1 such that vertical bar CS vertical bar = 3 for each i with 1 <= i <= s, vertical bar C-i vertical bar = 4 for each i with s + 1 <= i <= s + t and vertical bar Cs+t+1 vertical bar = n - 3s - 4t. Furthermore, the degree condition is sharp.","Title: On the number of disjoint 4-cycles in regular tournaments.\nYear: 2018\n\nAbstract: In this paper, we prove that for an integer r >= 1, every regular tournament T of degree 3r - 1 contains at least 21/16r - 10/3 disjoint directed 4-cycles. Our result is an improvement of Lichiardopol's theorem when taking q = 4 [Discrete Math. 3 1 0 (2010) 2567-2570]: for given integers q >= 3 and r >= 1, a tournament T with minimum out-degree and in-degree both at least (q - 1) r - 1 contains at least r disjoint directed cycles of length q.","Title: Fan-type condition on disjoint cycles in a graph.\nYear: 2018\n\nAbstract: Let k be a positive integer. In this paper, we prove that for a graph G with at least 4k vertices, if max{d(x),d(y)}≥2k for any pair of nonadjacent vertices {x,y}⊆V(G), then G contains k disjoint cycles. This generalizes the results given by Corrá di and Hajnal (1963), Enomoto (1998), and Wang (1999).","Title: Longitudinal And Multi-Modal Data Learning For Parkinson'S Disease Diagnosis\nYear: 2018\n\nAbstract: In this paper, we propose a joint regression and classification scheme for Parkinson's disease (PD) diagnosis using longitudinal multi-modal neuroimaging data. Specifically, we devise a new feature selection method imposing three kinds of relational constraints in a unified multi-task feature selection model. These relations (e.g., relations among features, responses, and subjects) are consolidated to represent the similarities among them. The baseline data is utilized to establish the feature selection model exploiting five regression variables (four clinical scores and a clinical label) to jointly select the most discriminative features. Namely, we exploit baseline data to train four regression models for clinical scores prediction and a classification model for discriminating the clinical label in the future time point. Extensive experiments are conducted to demonstrate the effectiveness of the proposed method on the Parkinson's Progression Markers Initiative (PPMI) dataset. The experimental results demonstrate that our proposed method can enhance the performance in clinical scores prediction and class label identification in longitudinal data and outperforms the state-of-art methods as well.","Title: Degree sum conditions on two disjoint cycles in graphs.\nYear: 2018\n\nAbstract: Let G be a simple undirected graph on n vertices. A set of subgraphs of G is disjoint if no two of them have any common vertex in G. Suppose that n1,n2 are two integers with n1,n2≥3 and n=n1+n2. We prove that if d(x)+d(y)≥n+4 for any pair of vertices x,y of G with xy∉E(G), then G contains two disjoint cycles of length n1 and n2.","Title: The confirmation of a conjecture on disjoint cycles in a graph.\nYear: 2018\n\nAbstract: Let t and k be two integers with t≥5 and k≥2. For a graph G and a vertex x of G, we use dG(x) to denote the degree of x in G. Define σt(G) to be the minimum value of ∑x∈XdG(x), where X is an independent set of G with |X|=t. This paper proves the following conjecture proposed by Gould et al. (2018). If G is a graph of sufficiently large order with σt(G)≥2kt−t+1, then G contains k vertex-disjoint cycles.","Title: Dynamic Hyper-Graph Inference Framework for Computer Assisted Diagnosis of Neurodegenerative Diseases.\nYear: 2019\n\nAbstract: Hyper-graph techniques have been widely investigated in computer vision and medical imaging applications, showing superior performance for modeling complex subject-wise relationships and sufficient flexibility to deal with missing data from multi-modal neuroimaging data. Existing hyper-graph methods, however, are inadequate for two reasons. First, representations are generated only from the observ...","Title: An improvement of Lichiardopol's theorem on disjoint cycles in tournaments.\nYear: 2019\n\nAbstract: Let k ≥ 1 and q ≥ 3 be integers and let f(q)=(6q2−16q+10)/(3q2−3q−4). In this paper, we prove that if q ≥ 4, then every tournament T with both minimum out-degree and in-degree at least (q−1)k−1 contains at least f(q)k−2q disjoint cycles of length q. We also prove that if q=3 and k ≥ 6, then T contains at least 16k/15−5 disjoint triangles. Our results improve Lichiardopol’s theorem ([Discrete Math. 310 (19) (2010) 2567–2570]): for given integers q ≥ 3 and k ≥ 1, a tournament T with both minimum out-degree and in-degree at least (q−1)k−1 contains at least k disjoint cycles of length q.","Title: Vertex-disjoint copies of K1, t in K1, r-free graphs.\nYear: 2017\n\nAbstract: Abstract A graph G is said to be K 1 , r -free if G does not contain an induced subgraph isomorphic to K 1 , r . Let k , r , t be integers with k ≥ 2 and t ≥ 3 . In this paper, we prove that if G is a K 1 , r -free graph of order at least ( k − 1 ) ( t ( r − 1 ) + 1 ) + 1 with δ ( G ) ≥ t and r ≥ 2 t − 1 , then G contains k vertex-disjoint copies of K 1 , t . This result shows that the conjecture in Fujita (2008) is true for r ≥ 2 t − 1 and t ≥ 3 . Furthermore, we obtain a weaker version of Fujita’s conjecture, that is, if G is a K 1 , r -free graph of order at least ( k − 1 ) ( t ( r − 1 ) + 1 + ( t − 1 ) ( t − 2 ) ) + 1 with δ ( G ) ≥ t and r ≥ 6 , then G contains k vertex-disjoint copies of K 1 , t .","Title: A low input power charge pump for passive UHF RFID applications\nYear: 2017\n\nAbstract: A novel charge pump with good performance in low-voltage is presented and implemented in UMC 0.18 um process that operates at UHF band of 860MHz to 960MHz. It uses auxiliary charge transfer switches (CTS's) and PMOS charge pump to generate bias voltage for the main charge pump to compensate for the threshold voltage (V\n<inf xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">th</inf>\n). The main charge pump is the Dickson rectifiers to double the input voltage. It has been used in an UHF RFID tag to generate supply voltage and occupies the chip area of 250um∗190um. The measurement result shows sensitivity of −10dBm for dc output voltage of 1.1V.","Title: A Stereo Visual Obstacle Detection Approach Using Fuzzy Logic And Neural Network In Agriculture\nYear: 2018\n\nAbstract: This paper describes a stereo visual obstacle detection approach using fuzzy logic and neural network in agriculture. Firstly, by training obstacle and non-obstacle colour features with a 6-input neural network, appearance_based method is applied to extract novel regions in monocular image. We apply improved FAST algorithm to extract features, which adapts illumination variation better. At last, we match feature points in the image pairs and obtain the disparity information. The results show that the algorithm is capable of detecting obstacles such as vehicles, humans, trees, plastic bar and other common obstacles in agricultural environment successfully.","Title: Monitoring and Analyzing Mountain Glacier Surface Movement Using SAR Data and a Terrestrial Laser Scanner: A Case Study of the Himalayas North Slope Glacier Area.\nYear: 2019\n\nAbstract: The offset tracking technique based on synthetic aperture radar (SAR) image intensity information can estimate glacier displacement even when glacier velocities are high and the time interval between images is long, allowing for the broad use of this technique in glacier velocity monitoring. Terrestrial laser scanners, a non-contact measuring system, can measure the velocity of a glacier even if there are no control points arranged on a glacier. In this study, six COSMO-SkyMed images acquired between 31 July and 22 December 2016 were used to obtain the glacial movements of five glaciers on the northern slope of the central Himalayas using the offset tracking approach. During the period of image acquirement, a terrestrial laser scanner was used, and point clouds of two periods in a small area at the terminus of the Pingcuoliesa Glacier were obtained. By selecting three fixed areas of the point clouds that have similar shapes across two periods, the displacements of the centers of gravity of the selected areas were calculated by using contrast analyses of feature points. Although the overall low-density point clouds data indicate that the glacial surfaces have low albedos relative to the wavelength of the terrestrial laser scanner and the effect of its application is therefore influenced in this research, the registration accuracy of 0.0023 m/d in the non-glacial areas of the scanner's measurements is acceptable, considering the magnitude of 0.072 m/d of the minimum glacial velocity measured by the scanner. The displacements from the point clouds broadly agree with the results of the offset tracking technique in the same area, which provides further evidence of the reliability of the measurements of the SAR data in addition to the analyses of the root mean squared error of the velocity residuals in non-glacial areas. The analysis of the movement of five glaciers in the study area revealed the dynamic behavior of these glacial surfaces across five periods. G089972E28213N Glacier, Pingcuoliesa Glacier and Shimo Glacier show increasing surface movement velocities from the terminus end to the upper part with elevations of 1500 m, 4500 m, and 6400 m, respectively. The maximum velocities on the glacial surface profiles were 31.69 cm/d, 62.40 cm/d, and 42.00 cm/d, respectively. In contrast, the maximum velocity of Shie Glacier, 50.60 cm/d, was observed at the glacier's terminus. For each period, G090138E28210N Glacier exhibited similar velocity values across the surface profile, with a maximum velocity of 39.70 cm/d. The maximum velocities of G089972E28213N Glacier, Pingcuoliesa Glacier, and Shie Glacier occur in the areas where the topography is steepest. In general, glacial surface velocities are higher in the summer than in the winter in this region. With the assistance of a terrestrial laser scanner with optimized wavelengths or other proper ground-based remote sensing instruments, the offset tracking technique based on high-resolution satellite SAR data should provide more reliable and detailed information for local and even single glacial surface displacement monitoring.","Title: Concrete Crack Detection and Monitoring Using a Capacitive Dense Sensor Array.\nYear: 2019\n\nAbstract: Cracks in concrete structures can be indicators of important damage and may significantly affect durability. Their timely identification can be used to ensure structural safety and guide on-time maintenance operations. Structural health monitoring solutions, such as strain gauges and fiber optics systems, have been proposed for the automatic monitoring of such cracks. However, these solutions become economically difficult to deploy when the surface under investigation is very large. This paper proposes to leverage a novel sensing skin for monitoring cracks in concrete structures. This sensing skin is constituted of a flexible electronic termed soft elastomeric capacitor, which detects a change in strain through changes in measured capacitance. The SEC is a low-cost, durable, and robust sensing technology that has previously been studied for the monitoring of fatigue cracks in steel components. In this study, the sensing skin is introduced and preliminary validation results on a small-scale reinforced concrete beam are presented. The technology is verified on a full-scale post-tensioned concrete beam. Results show that the sensing skin is capable of detecting, localizing, and quantifying cracks that formed in both the reinforced and post-tensioned concrete specimens.","Title: A novel design of experiment algorithm using improved evolutionary multi-objective optimization strategy\nYear: 2021\n\nAbstract: The paper aims to propose an intelligent design of experiment (DOE) algorithm using an improved evolutionary multi-objective optimization approach. Adaptive evolutionary strategies are embedded in the algorithm to support the design of simulation test schemes with multiple factors whose levels are same or different. Comparative results with several existing DOE algorithms show better sampling capacity and fine sampling efficiency of the proposed algorithm. Application effects of a complex flight simulator indicate the algorithm a wide technological prospect of serving well certain complex systems.","Title: Pixel-Level Fatigue Crack Segmentation In Large-Scale Images Of Steel Structures Using An Encoder-Decoder Network\nYear: 2021\n\nAbstract: Fatigue cracks are critical types of damage in steel structures due to repeated loads and distortion effects. Fatigue crack growth may lead to further structural failure and even induce collapse. Efficient and timely fatigue crack detection and segmentation can support condition assessment, asset maintenance, and management of existing structures and prevent the early permit post and improve life cycles. In current research and engineering practices, visual inspection is the most widely implemented approach for fatigue crack inspection. However, the inspection accuracy of this method highly relies on the subjective judgment of the inspectors. Furthermore, it needs large amounts of cost, time, and labor force. Non-destructive testing methods can provide accurate detection results, but the cost is very high. To overcome the limitations of current fatigue crack detection methods, this study presents a pixel-level fatigue crack segmentation framework for large-scale images with complicated backgrounds taken from steel structures by using an encoder-decoder network, which is modified from the U-net structure. To effectively train and test the images with large resolutions such as 4928 x 3264 pixels or larger, the large images were cropped into small images for training and testing. The final segmentation results of the original images are obtained by assembling the segment results in the small images. Additionally, image post-processing including opening and closing operations were implemented to reduce the noises in the segmentation maps. The proposed method achieved an acceptable accuracy of automatic fatigue crack segmentation in terms of average intersection over union (mIOU). A comparative study with an FCN model that implements ResNet34 as backbone indicates that the proposed method using U-net could give better fatigue crack segmentation performance with fewer training epochs and simpler model structure. Furthermore, this study also provides helpful considerations and recommendations for researchers and practitioners in civil infrastructure engineering to apply image-based fatigue crack detection.","Title: Vertex-Disjoint Stars In K-1,K-R-Free Graphs\nYear: 2021\n\nAbstract: A graph G is said to be K-1,K-r-free if G does not contain an induced subgraph isomorphic to K-1,K-r. Let k, r, t be integers with k >= 2, r >= 3 and t >= 2. Fujita (2008) conjectured that if G is a K-1,K-r-free graph of order at least (k - 1)(t(r - 1) + 1) + 1 with minimum degree at least t, then G contains k disjoint copies of K-1,K-t. In this paper, we show that this conjecture is true for the case r > t >= 3 and for the case r = t = 4, and we also show that this conjecture is true if vertical bar V(G)vertical bar >= (k - 1)(t(2) - 2) + 1 and t >= r >= 4. (C) 2021 Elsevier B.V. All rights reserved.","Title: Regression and Evaluation on a Forward Interpolated Version of the Great Circle Arcs-Based Distortion Metric of Map Projections\nYear: 2021\n\nAbstract: We studied the numerical approximation problem of distortion in map projections. Most widely used differential methods calculate area distortion and maximum angular distortion using partial derivatives of forward equations of map projections. However, in certain map projections, partial derivatives are difficult to calculate because of the complicated forms of forward equations, e.g., equations with iterations, integrations, or multi-way branches. As an alternative, the spherical great circle arcs-based metric employs the inverse equations of map projections to transform sample points from the projection plane to the spherical surface, and then calculates a differential-independent distortion metric for the map projections. We introduce a novel forward interpolated version of the previous spherical great circle arcs-based metric, solely dependent on the forward equations of map projections. In our proposed numerical solution, a rational function-based regression is also devised and applied to our metric to obtain an approximate metric of angular distortion. The statistical and graphical results indicate that the errors of the proposed metric are fairly low, and a good numerical estimation with high correlation to the differential-based metric can be achieved.","Title: How to promote COVID-19 pandemic prevention and control: A game theory analysis\nYear: 2021\n\nAbstract: The outbreak of the COVID-19 (Corona Virus Disease 2019) has been becoming the most serious public health event in the world, threatening the health of hundreds of millions of people. The anti-pandemic policies mostly aim to prevent the spread at domestic and the import from abroad. In this paper, we discuss the issue of individual protection measures and customs quarantine strategy based on game theory. First, we develop a 2*2 Bayesian model and show that individual protection decisions depend on the size of excess payoff of taking protective measures (EPP). EPP is affected by the protection cost, the protective efficiency, the risk exposure and the information disclosure in this model. Then, we describe a repeated game between customs and airlines, and discuss the ideal strategy for customs to prevent the virus input. It comes out that a punishment mechanism for an airline is meaningful to prevent the import of the virus only if the discount rate of the airline is greater than the threshold. The threshold is positively correlated with the detection cost, and it is negatively correlated with the revenue of the airline and the testing reliability. We can also benefit from establishing a credit mechanism to give airlines that deviate from cooperation an opportunity to re-cooperate, especially for those in low risk areas. This study provides theoretical support for some government policies to prevent COVID-19, and underscores the significance of considering individual and organizational decision-making in health policy making.","Title: Image-Based Angular Distortion Metric of Map Projections by Using Surface Fitting for Noise Reduction\nYear: 2022\n\nAbstract: Measuring, analyzing, reducing, and optimizing distortions in map projections is important in cartography. In this study, we introduced a novel image-based angular distortion metric based on the previous spherical great circle arcs-based metric. Images with predefined patterns were used to generate distorted images using mapping software. The generated distorted images with known patterns were then exploited to calculate the proposed angular distortion metric. The mapping software performed the underlying transformation of map projections. Therefore, there was no direct explicit dependence on the forward equations of the map projections in our proposed metric. However, there were fairly large computation errors in the ordinary image-based approach without special correction. To reduce the error, we introduced surface-fitting-based noise reduction in our approach. We established and solved systems of linear equations based on bivariate polynomial functions in the process of noise reduction. Sufficient experiments were made to validate the proposed image-based metric and the accompanying noise reduction approach. In the experiment, the NASA G.Projector was employed as the mapping software for evaluating more than 200 map projections. Experimental results demonstrated that the proposed image-based approach and surface fitting-based noise reduction are feasible and practical for the evaluation of the angular distortion of map projections.","Title: <p>Disjoint cycles and 2-factors with Fan-type condition in a graph</p>\nYear: 2022\n\nAbstract: Let k be a positive integer. For a graph G, let sigma(2)(1) (G) be the minimum value of max{d(x), d(y)} for any pair of nonadjacent vertices x and y. Corr & aacute;di and Hajnal proved that every graph G of order n >=& nbsp;3k with delta(G) >=& nbsp;2k contains k disjoint cycles. In this paper, we generalize this theorem by proving that, for a graph G of order at least 3k + 2, if sigma(2)(1)(G) >=& nbsp;2k, then G contains k disjoint cycles. The bound of order is sharp. Based on this result, we show that if G is a 2-connected graph of order at least 3k + 5 with sigma(2)(1)(G) >=& nbsp;max{n/2, 2k + 2}, then G contains a 2-factor with exactly k disjoint cycles, which improves the theorem of Brandt et al. (1997) [2]. (C)& nbsp;2021 Elsevier B.V. All rights reserved.","Title: Cycle Extendability in Extended Tournaments\nYear: 2022\n\nAbstract: An extended tournament is an orientation of a \n \n \n \n $$c (\\ge 2)$$\n \n -partite complete graph such that if there is one arc between two partite sets, say from \n \n \n \n $$V_i$$\n \n to \n \n \n \n $$V_j$$\n \n , then there is an arc from every vertex in \n \n \n \n $$V_i$$\n \n to every vertex in \n \n \n \n $$V_j$$\n \n . In this paper, we show the following. Let T be an extended tournament with \n \n \n \n $$c\\ge 4$$\n \n partite sets. For every non-Hamiltonian cycle C in T there is a cycle \n \n \n \n $$C^\\prime $$\n \n such that \n \n \n \n $$V (C) \\subset V (C^\\prime )$$\n \n and \n \n \n \n $$|C^\\prime |\\le |C| + 2$$\n \n if and only if T is Hamiltonian. Moreover, we give two examples to prove that the condition \n \n \n \n $$c\\ge 4$$\n \n is needed, and there exists an infinite family of extended tournaments which are Hamiltonian but have no cycle \n \n \n \n $$C^\\prime $$\n \n such that \n \n \n \n $$V (C) \\subset V (C^\\prime )$$\n \n and \n \n \n \n $$|C^\\prime |= |C| + 1$$\n \n for a non-Hamiltonian cycle C in T.","Title: A hybrid crossover multi-agent multi-objective evolutionary algorithm and its application in microgrid operation optimization\nYear: 2022\n\nAbstract: The power generation industry needs to adopt renewable energy so as to reduce the utilization of fossil energy and pollution emission. In renewable energy power generation, microgrid operation optimization needs to consider multiple objectives such as economy and environmental protection, which is a multi-objective optimization problem Aiming at the multi-objective optimization problem, based on the Pareto optimal concept, a hybrid crossover multi-agent multi-objective evolutionary algorithm is proposed and applied to the multi-objective optimization problem of microgrid systems, in which the economical cost and environmental protection are considered. The simulation results under three operating conditions show that compared with the classical NSGA-66 algorithm, the proposed algorithm can obtain higher quality Pareto optimal solution in a shorter time. The efficiency of the proposed algorithm in this problem is higher than that of the classical NSGA-66 algorithm. It can provide a higher quality solution for the optimal operation of a microgrid.","Title: MCS Analysis for 5G-NR V2X Sidelink Broadcast Communication\nYear: 2022\n\nAbstract: Leveraging Modulation and Coding Schemes (MCS) in 5G New Radio (NR) Sidelink represents one key strategy to provide sufficient capacity required by future 5G for Vehicle-to-Everything (V2X) services for intelligent vehicles. Early studies either directly adopt the previously optimised QPSK 1/2 by 802.11p/C-V2X or suggest an optimal MCS value under a particular context. In this paper, we identify a MCS value optimal under any context, by evaluating the impact of MCS on V2X broadcast communication considering multiple varying parameters (e.g. variable packet size, transmit rate or density) representative of different 5G V2X services.","Title: Multi-Source Time Series Remote Sensing Feature Selection and Urban Forest Extraction Based on Improved Artificial Bee Colony\nYear: 2022\n\nAbstract: Urban forests maintain the ecological balance of cities and are significant in promoting the sustainable development of cities. Therefore, using advanced remote sensing technology to accurately extract forest green space in the city and monitor its change in real-time is very important. Taking Nanjing as the study area, this research extracted 55 vegetation phenological features from Sentinel-2A time series images and formed a feature set containing 81 parameters together with 26 features, including polarimetric- and texture-related information extracted from dual-polarization Sentinel-1A data. On the basis of the improved ABC (ABC-LIBSVM) feature selection method, the optimal feature subset was selected, and the forest coverage areas in the study area were accurately described. To verify the feasibility of the improved feature selection method and explore the potential for the development of multi-source time series remote sensing for urban forest feature extraction, this paper also used the random forest classification model to classify four different feature sets. The results revealed that the classification accuracy based on the feature set obtained by the ABC-LIBSVM algorithm was the highest, with an overall accuracy of 86.80% and a kappa coefficient of 0.8145. The producer accuracy and user accuracy of the urban forest were 93.21% and 82.45%, respectively. Furthermore, by combining the multi-source time series Sentinel-2A optical images with Sentinel-1A dual-polarization SAR images, urban forests can be distinguished from the perspective of phenology, and polarimetric- and texture-related features can contribute to the accurate identification of forests.","Title: A Federated Learning Backdoor Attack Defense Method Based on Dual Attention Mechanism\nYear: 2022\n\nAbstract: As a distributed machine learning paradigm, federated learning allows clients to collaboratively train models without sharing their private data, effectively solving data privacy issues in edge computing scenarios. However, recent studies have shown that neural network models in federated learning are vulnerable to backdoor attacks, which make the global model give wrong inference results in a high-confidence manner, such as recognizing stop signs as speed limit signs in the image classification task. This will have serious consequences. Aiming at the problem that the existing federated learning defense methods take a long time to compute and cannot destroy the matching relationship between triggers and backdoors, a federated learning backdoor attack defense based on dual attention mechanism (FDDAM) is proposed. The model weights are dynamically adjusted during training process, no additional models are required, and the calculation time is shorter. First, in order for the model to ignore triggers, the enhancement on image semantics is performed and then build channel attention map. Second, in order to destroy the matching relationship between triggers and backdoors, a feature map space transformation network is constructed. Finally, in order to improve the defense success rate, the channel attention map and the spatial attention map are weighted to construct a dual attention network. Experiments with FDDAM on image classification datasets show an average increase of 1.68% and 3.11% in model accuracy and defense success rate, and an average reduction of 1.85 times in computation time compared to the benchmark method."],"string":"[\n \"Title: Stiffness analysis and optimization of a novel cable driven anthropomorphic-arm manipulator\\nYear: 2012\\n\\nAbstract: Cartesian stiffness of a 7-DOF(degree-of-freedom) hybrid cable-driven anthropomorphic-arm manipulator(CDAM) was analyzed,in which the shoulder module and wrist module were both 3-DOF cable-driven spherical joint(CDSJ).The calculation process of Cartesian stiffness matrix of the manipulator was demonstrated in detail through the analysis of the stiffness of CDSJ combined with the solution for the stiffness of serial manipulators.The calculation process could be divided into three steps: firstly,the analysis of CDSJ stiffness was introduced to solve the stiffness of shoulder and wrist;secondly,the stiffness of elbow,a cable-driven revolute joint,was calculated;lastly,by merging the stiffness of the wrist,elbow and shoulder module to the joint stiffness matrix,the modified conservative congruence transformation(CCT) was used to get the solution of Cartesian stiffness matrix of CDAM.Based on the stiffness analysis of CDAM,a stiffness optimal algorithm was proposed to enhance the stiffness in motion.The simulation result proves the effectiveness of the algorithm.\",\n \"Title: Every 3-connected claw-free Z8-free graph is Hamiltonian\\nYear: 2010\\n\\nAbstract: In this article, we first show that every 3-edge-connected graph with circumference at most 8 is supereulerian, which is then applied to show that a 3-connected claw-free graph without Z8 as an induced subgraph is Hamiltonian, where Z8 denotes the graph derived from identifying one end vertex of P9 (a path with 9 vertices) with one vertex of a triangle. The above two results are both best possible in a sense that the number 8 cannot be replaced by 9 and they also extend former results by Brousek et al. in (Discrete Math 196 (1999), 29–50) and by Łuczak and Pfender in (J Graph Theory 47 (2004), 111–121). © 2009 Wiley Periodicals, Inc. J Graph Theory 64: 1–11, 2010\",\n \"Title: Pseudo-Coloring Occlusion Culling\\nYear: 2012\\n\\nAbstract: A novel algorithm called Pseudo-Coloring Occlusion Culling (PCOC) approach was proposed for complicated models and integrated with an open source 3D graphics engine. In the PCOC, a complicated model was tessellated to a simplified model and the simplified model was rendered to a texture with pseudo-colors in real-time. Then, according to the pseudo-coloring texture, the visibility parts of the complicated model were determined automatically. In this paper, the efficient real-time pseudo-coloring method was applied in an automobile display system. The result indicated that the pseudo-coloiing algorithm reduced 45% invisible triangles, increased 63% of frame rate and improved the performance of real-time rendering.\",\n \"Title: Rimless wheel with radially expanding spokes: dynamics, impact, and stable gait\\nYear: 2004\\n\\nAbstract: This paper describes the dynamics and intermittent impact model of a novel rimless wheel with radially expanding spokes confined to move in a vertical plane. The wheel has two degrees of freedom, namely rotation in the plane and change of radius. The system has intermittent impacts with the ground and its mathematical model is discontinuous. The motions of the wheel on a horizontal and an inclined plane are investigated. The contact point of the wheel with the ground is assumed to have no slip. We derive the equations of motion in between the collisions and velocity change before and after the wheel impact. We construct the return map of its cyclic motion and plan the motion in between impacts to obtain a stable gait. Dynamic simulations are performed using MATLAB and are presented in the paper.\",\n \"Title: An improved lower bound for a bi-criteria scheduling problem\\nYear: 2008\\n\\nAbstract: For the bi-criteria scheduling problem of minimizing the sum of completion times and the sum of weighted completion times, min-sum of weighted completion times, we prove that there exists no constant @b1 such that (1+1/@c,@b)-approximate schedules can be found for any @c0. This result confirms a recently published conjecture.\",\n \"Title: Research on Automatic Large Scale Terrain Modeling.\\nYear: 2012\\n\\nAbstract: As manual interventions in conventional large scale terrain modeling process results in low efficiency, this paper proposes an automatic terrain modeling method (ATMM) aiming to reconstruct terrain meshes taking advantage of remote sensing images with few manual interventions. The modeling method includes acquiring and processing digital elevation model (DEM), establishing topological relations between spatial points and interpolating elevation. Definitions and basic properties of several existing Delaunay triangulations are discussed and the spatial points' topologies are constructed with the Delaunay triangulation template in Computational Geometry Algorithms Library (CGAL). An algorithm efficiency validation on a terrain with 18750X 18750 points demonstrates the ATMM is acceptably competent for accelerating the speed of terrain modeling procedure.\",\n \"Title: Intelligent Decoupling Control of Gas Collection Process of Multiple Asymmetric Coke Ovens\\nYear: 2009\\n\\nAbstract: This paper presents a hierarchical intelligent decoupling control method for the gas collection process of three asymmetric coke ovens of an iron and steel company. The process features strong asymmetric coupling, large disturbances, and strong nonlinearity. These characteristics are exploited in the following steps to implement intelligent decoupling control. First, three fuzzy expert controllers and two feedforward controllers stabilize the pressure of each gas collector. Then, the three collectors are divided into two groups based on an analysis of the couplings among them to facilitate decoupling control. An intelligent decoupling control method is used to design intragroup and intergroup decoupling controllers. Finally, expert valve control handles the nonlinearity of butterfly valves, and a multirate sampling strategy further improves the control performance. The results of actual runs show that the system satisfactorily performs the intelligent decoupling control of the gas pressures of the coke ovens, sufficiently suppresses disturbances, and accurately stabilizes the pressures.\",\n \"Title: On 2-Factors with Chorded Quadrilaterals in Graphs.\\nYear: 2011\\n\\nAbstract: Let k be a positive integer and G a graph with order n >= 4k + 3. It is proved that if the minimum degree sum of any two nonadjacent vertices is at least n + k, then G contains a 2-factor with k + 1 disjoint cycles, C(1,) ..., C(k)+i such that C(i) are chorded quadrilateral for 1 <= i <= k - 1 and the length of C(k) is at most 4.\",\n \"Title: A 3D model simplification algorithm based on edge-collapse\\nYear: 2012\\n\\nAbstract: In computer graphics, 3D model is often represented by triangle meshes. A complicated scene sometimes consists of considerable meshes, which is very difficult to store, transmit and render. This paper introduces an improved mesh simplification algorithm based on edge-collapse. This algorithm utilizes quadric error metric to compute the vertex significance and control the sequence of edge collapse. The experimental results show that the new algorithm can reserve original shape features at low levels of detail.\",\n \"Title: Sparse self-calibration by map method for MIMO radar imaging\\nYear: 2012\\n\\nAbstract: Multiple-input multiple-output (MIMO) radar is expected to achieve good inversion performance by utilizing space diversity technology. However, traditional imaging methods often fail owing to the practical constraints that the available transmitters and receivers are very few and the number of snapshots is very limited. More seriously, the unavoidable position errors of the transmitters and the receivers would further deteriorate the imaging results. In this paper, by exploiting the sparse priority of the target, the sparse self-calibration by maximum a posterior probability method (SSC-MAP) is proposed to provide high resolution image and realize accurate position calibration at the same time. Numerical simulations verify the effectiveness of the proposed method.\",\n \"Title: Braking Process Modeling and Simulation of CRH2 Electric Multiple Unit\\nYear: 2012\\n\\nAbstract: Train braking process was greatly affected by factors such as environment, line condition and train driver operation proficiency. How to establish train braking process model and determine the effective braking control strategy is the foundation of achieving the safe and reliable operation of the train. By taking the CRH2 -300 Electric Multiple Unit(EMU) as an example, based on the train braking process operation characteristics and brake deceleration mode curve, multiple models description method for its braking process have been developed with the data-driven modeling. And the efficiency of model is verified with China train control system level 3(CTCS-3). Simulation results show the established braking process model is suitable not only for the common brake but also has high tracking accuracy for the emergency brake. Furthermore, the model is satisfied with requirement of emergency braking distance that should less than 3700m as well as reduces the energy consumption.\",\n \"Title: Graph partition into small cliques\\nYear: 2014\\n\\nAbstract: Let s and k be two integers with 0 ¿ s ¿ k and let G be a simple graph of order n . This paper investigates clique partition problems. It is proved that if n ¿ 3 s + 4 ( k - s ) and d ( u ) + d ( v ) ¿ 3 ( n - s ) / 2 + k - 1 for any pair of non-adjacent vertices u , v of G , then G contains s vertex-disjoint K 3 s and k - s vertex-disjoint K 4 s such that all of them are vertex-disjoint. Moreover, the degree condition is sharp.\",\n \"Title: Neighborhood Unions for the Existence of Disjoint Chorded Cycles in Graphs\\nYear: 2013\\n\\nAbstract: chorded cycle is a cycle with at least one chord. We prove that if G is a simple graph with order n 4 k and $${|N_G(x)\\\\cup N_G(y)|\\\\geq 4k+1}$$ for each nonadjacent pair of vertices x and y , then G contains k vertex-disjoint chorded cycles. The degree condition is sharp in general.\",\n \"Title: Contractible configurations on 3-flows in graphs satisfying the Fan-condition\\nYear: 2013\\n\\nAbstract: Let G be a 2-edge-connected graph of order n such that each pair of vertices x and y at distance 2 satisfies max{d(x),d(y)}n2 (weak Fan-condition, [G.H. Fan, New sufficient conditions for cycles in graphs, J. Combin. Theory Ser. B 37 (1984) 221-227]). It is obtained in this paper that G admits a nowhere-zero 3-flow and is a 3-flow contractible configuration except for a family of well-characterized counterexamples. This result generalizes some earlier results about 3-flows, 3-flow contractible configurations under some degree-sum conditions ([G. Fan, C. Zhou, Ore condition and nowhere-zero 3-flows, SIAM J. Discrete Math. 22 (2008) 288-294], [R. Luo, R. Xu, J.H. Yin, G.X. Yu, Ore-condition and Z\\\"3-connectivity, European J. Combin. 29 (2008) 1587-1595]).\",\n \"Title: Vertex-disjoint triangles in K1,t-free graphs with minimum degree at least t\\nYear: 2010\\n\\nAbstract: graph is said to be K\\\"1\\\",\\\"t-free if it does not contain an induced subgraph isomorphic to K\\\"1\\\",\\\"t. Let h(t,k) be the smallest integer m such that every K\\\"1\\\",\\\"t-free graph of order greater than m and with minimum degree at least t contains k vertex-disjoint triangles. In this paper, we obtain a lower bound of h(t,k) by a constructive method. According to the lower bound, we totally disprove the conjecture raised by Hong Wang [H. Wang, Vertex-disjoint triangles in claw-free graphs with minimum degree at least three, Combinatorica 18 (1998) 441-447]. We also obtain an upper bound of h(t,k) which is related to Ramsey numbers R(3,t). In particular, we prove that h(4,k)=9(k-1) and h(5,k)=14(k-1).\",\n \"Title: Degree conditions for the partition of a graph into triangles and quadrilaterals\\nYear: 2010\\n\\nAbstract: For two positive integers r and s with r >= 2s - 2, if G is a graph of order 3r + 4s such that d(x) + d(y) >= 4r + 4s for every xy is not an element of E(G), then G independently contains r triangles and s quadrilaterals, which partially prove the El-Zahar's Conjecture.\",\n \"Title: Notes on Hamiltonian Graphs and Hamiltonian-Connected Graphs.\\nYear: 2013\\n\\nAbstract: Let G = (V (G), E(G)) be a graph and alpha(G) be the independence number of G. For a vertex v is an element of V(G), d(v) and N(v) represent the degree and the neighborhood of v in G, respectively. In this paper, we prove that if G is a k-connected(k >= 2) graph of order n, and if max{d(v) : v is an element of S} >= n/2 for every independent set S of G with vertical bar S vertical bar = k which has two distinct vertices x, y is an element of S satisfying 1 <= vertical bar N(x) boolean AND N(y)vertical bar <= alpha(G) - 2, then either G is hamiltonian or else G belongs to one of a family of exceptional graphs. We also give a similar sufficient condition for Hamiltonian-connected graphs.\",\n \"Title: Adaptive control of uncertain Hammerstein systems with monotonic input nonlinearities using auxiliary nonlinearities\\nYear: 2012\\n\\nAbstract: We extend retrospective cost adaptive control (RCAC) to command following for uncertain Hammerstein systems. We assume that only one Markov parameter of the linear plant is known and that the input nonlinearity is monotonic but otherwise unknown. Auxiliary nonlinearities are used within RCAC to account for the effect of the input nonlinearity.\",\n \"Title: Automated segmentation of CBCT image using spiral CT atlases and convex optimization.\\nYear: 2013\\n\\nAbstract: Cone-beam computed tomography (CBCT) is an increasingly utilized imaging modality for the diagnosis and treatment planning of the patients with craniomaxillofacial (CMF) deformities. CBCT scans have relatively low cost and low radiation dose in comparison to conventional spiral CT scans. However, a major limitation of CBCT scans is the widespread image artifacts such as noise, beam hardening and inhomogeneity, causing great difficulties for accurate segmentation of bony structures from soft tissues, as well as separating mandible from maxilla. In this paper, we presented a novel fully automated method for CBCT image segmentation. In this method, we first estimated a patient-specific atlas using a sparse label fusion strategy from predefined spiral CT atlases. This patient-specific atlas was then integrated into a convex segmentation framework based on maximum a posteriori probability for accurate segmentation. Finally, the performance of our method was validated via comparisons with manual ground-truth segmentations.\",\n \"Title: Disjoint triangles and quadrilaterals in a graph\\nYear: 2008\\n\\nAbstract: Let G be a simple graph of order n and s and k be two positive integers. Brandt et al. obtained the following result: If s= =3s+4(k-s) and @s\\\"2(G)>=n+s, then G contains k disjoint cycles C\\\"1,...,C\\\"k satisfying |C\\\"i|=3 for 1= =3s+4(k-s)+3.\",\n \"Title: Nowhere-zero 3-flows and Z3-connectivity of a family of graphs\\nYear: 2011\\n\\nAbstract: Tutte conjectured that every 4-edge-connected graph admits a nowhere-zero 3-flow. Jaeger et al. [F. Jaeger, N. Linial, C. Payan, M. Tarsi, Group connectivity of graphs-a nonhomogeneous analogue of Nowhere-zero flow properties, J. Combin. Theory, Ser. B 56 (1992) 165-182] conjectured that every 5-edge-connected graph is Z\\\\\\\"3- connected. Let G be a simple connected graph with n vertices. It is proved in this paper that ifd(u)+d(v)=nfor each pair of verticesu,vwith distance two, then (1) Gadmits a nowhere-zero 3-flow if and only ifGis none of 7 excluded graphs; (2) GisZ\\\\\\\"3-connected if and only ifGis none of 15 excluded graphs. The first theorem strengthens an early result by Fan et al. [ G. Fan, C. Zhou. Ore condition and Nowhere-zero 3-flows, SIAM J. Discrete Math., 22 (2008) 288-294] and the second theorem strengthens an early result by Luo, et al. [ R. Luo, R. Xu, J.H. Yin, G.X. Yu, Ore-condition and Z\\\\\\\"3-connectivity, European J. Combin., 29 (2008) 1587-1595].\",\n \"Title: Fault detection for aircraft control surfaces using approximate input reconstruction\\nYear: 2009\\n\\nAbstract: We use an approximate input reconstruction algorithm to reconstruct unknown inputs, which are then used as a basis for fault detection. The approximate input reconstruction algorithm is a least squares algorithm that estimates both the unknown initial state and input history. The estimated inputs are then compared to the commanded values and sensor values to assess the health of actuators and sensors. This approach is applied to the longitudinal and lateral dynamics of an aircraft. The input reconstruction algorithm can be used for minimum-phase or nonminimum-phase zeros; however, zeros on the unit circle yield persistent estimation errors and thus poor input reconstruction.\",\n \"Title: On 2-factors with cycles containing specified edges in a bipartite graph\\nYear: 2009\\n\\nAbstract: Let k>=1 be an integer and G=(V\\\"1,V\\\"2;E) a bipartite graph with |V\\\"1|=|V\\\"2|=n such that n>=2k+2. In this paper it has been proved that if for each pair of nonadjacent vertices [email protected]?V\\\"1 and [email protected]?V\\\"2, d(x)+d(y)>[email protected][email protected]?, then for any k independent edges e\\\"1,...,e\\\"k of G, G has a 2-factor with k+1 cycles C\\\"1,...,C\\\"k\\\"+\\\"1 such that e\\\"[email protected]?E(C\\\"i) and |V(C\\\"i)|=4 for each [email protected]?{1,...,k}. We shall also show that the conditions in this paper are sharp.\",\n \"Title: Compare and Analysis of Security Strategy in WAP and I-Mode Network\\nYear: 2008\\n\\nAbstract: This paper presents the security strategy used by WAP and I-Mode. It includes security transport protocol, the type of certificate, the performance of gateway, smartcard and authenticate scheme. It will first be illustrated from the architecture, and then discussed application situation. All of these schemes of WAP will be compared with the similar adopted technology of I-Mode. Through comparing, deficiencies of both WAP and I-Mode were uncovered. Methods to resolve these security problems were proposed at the end of this paper. The overall results derived from this work show WAP has more detailed, more general and more secure security scheme than I-Mode.\",\n \"Title: Real-Time Rendering and Animating of Grass.\\nYear: 2012\\n\\nAbstract: Real-time rendering of grass scenes is challenging for the geometric complexity and great volume of data. In this paper, a combination approach of geometry-based, volume slice-based and image-based techniques for grass rendering is proposed. Different levels of detail (LOD) are sequentially applied depending on the distance between models and camera. Seamless transition between two levels of detail is attained by hybrid models and fade-out method. Grass distribution is managed by density and height map based on geographic information system (GIS) data. In this method, it is possible to effectively conduct the simulation of large-scale grass scenes in real-time. The movement of grass with the wind is considered as a single degree of freedom (SDOF) vibration system. We realize the grass animation with shader in real-time and obtain acceptable results.\",\n \"Title: On 2-Factors With Quadrilaterals Containing Specified Vertices In A Bipartite Graph\\nYear: 2007\\n\\nAbstract: In this paper we consider the problem as follows: Given a bipartite graph G = (V-1, V-2; E) with vertical bar V-1 vertical bar = vertical bar V-2 vertical bar = n and a positive integer k, what degree condition is sufficient to ensure that for any k distinct vertices v(1), v(2), center dot center dot center dot, v(k) of G, G contains k independent quadrilaterals Q(1), Q(2), center dot center dot center dot, Q(k) such that v(i) is an element of V (Q(i)) for every i is an element of {1, 2, center dot center dot center dot, k}, or G has a 2-factor with k independent cycles of specified lengths with respect to {v(1), v(2), center dot center dot center dot, v(k)}? We will prove that if d(x) + d(y) >= [(4n + k)/3] for each pair of nonadjacent vertices x is an element of V-1 and y is an element of V-2, then, for any k distinct vertices v(1), v(2), center dot center dot center dot, v(k) of G, G contains k independent quadrilaterals Q(1), Q(2), center dot center dot center dot, Q(k) such that v(i) is an element of V(Q(i)) for each i is an element of {1, center dot center dot center dot, k}. Moreover, G has a 2-factor with k cycles with respect to {v(1),v(2), center dot center dot center dot, v(k)} such that k-1 of them are quadrilaterals. We also discuss the degree conditions in the above results.\",\n \"Title: Palmprint verification based on genetic algorithm\\nYear: 2008\\n\\nAbstract: This paper proposes a novel idea based feature selection in the verification system of palmprint, which can realize the specific feature selection for different user using genetic algorithm (GA). In the stage of enrollment, discrete wavelet transforms (DWT) and statistical methods are first used for feature extraction. Then GA is employed for feature selection, which means that each user has a specific feature index and verification modality. In the stage of verification, according to the feature index, the selected features are input to the related support vector machine (SVM) for classification. We test the proposed method on Hong Kong Polytechnic University Palmprint Database. Through the comparison, the experimental results show that our proposed method is effective and can reach high performance. © 2008 IEEE.\",\n \"Title: Color degree and heterochromatic paths in edge-colored graphs.\\nYear: 2014\\n\\nAbstract: Let G be an edge-colored graphs. A heterochromatic path of G is such a path in which no two edges have the same color. Let g(c)(G) and d(c)(nu) denote the heterochromatic girth and the color degree of a vertex nu of G, respectively. In this paper, some color degree and heterochromatic girth conditions for the existence of heterochromatic paths are obtained.\",\n \"Title: Adaptive control of uncertain Hammerstein systems with non-monotonic input nonlinearities using auxiliary nonlinearities\\nYear: 2013\\n\\nAbstract: We extend retrospective cost adaptive control (RCAC) with auxiliary nonlinearities to command following for uncertain Hammerstein systems with non-monotonic input nonlinearities. We assume that only one Markov parameter of the linear plant is known and that the non-monotonic input nonlinearity is uncertain. Auxiliary nonlinearities are used within RCAC to account for the non-monotonic input nonlinearity. The required modeling information for the input nonlinearity includes the intervals of monotonicity as well as values of the nonlinearity that determine overlapping segments of the range of the nonlinearity within each interval of monotonicity.\",\n \"Title: Estimating anatomically-correct reference model for craniomaxillofacial deformity via sparse representation.\\nYear: 2014\\n\\nAbstract: The success of craniomaxillofacial (CMF) surgery depends not only on the surgical techniques, but also upon an accurate surgical planning. However, surgical planning for CMF surgery is challenging due to the absence of a patient-specific reference model. In this paper, we present a method to automatically estimate an anatomically correct reference shape of jaws for the patient requiring orthognathic surgery, a common type of CMF surgery. We employ the sparse representation technique to represent the normal regions of the patient with respect to the normal subjects. The estimated representation is then used to reconstruct a patient-specific reference model with \\\"restored\\\" normal anatomy of the jaws. We validate our method on both synthetic subjects and patients. Experimental results show that our method can effectively reconstruct the normal shape of jaw for patients. Also, a new quantitative measurement is introduced to quantify the CMF deformity and validate the method in a quantitative approach, which is rarely used before.\",\n \"Title: A three-wheel vehicle with expanding wheels: differential flatness, trajectory planning, and control\\nYear: 2003\\n\\nAbstract: This paper describes the analysis and simulation of a novel 3-wheel vehicle with expanding wheels. The motivation for this design is to attain added navigation capability by expanding the wheels according to the requirements of the terrain. For this vehicle, we present the analysis of motions in the plane and in 3D space. In these models, it is assumed that the contact point of the wheel with the ground is directly underneath the center of the wheel and has no slip. The kinematic models are studied for the property of differential flatness and this property is used to plan the trajectory and design feedback controllers. The paper presents simulations performed using MATLAB. Currently, a vehicle with these features has been fabricated at University of Delaware.\",\n \"Title: Averaged ratio between complementary profiles for evaluating shape distortions of map projections and spherical hierarchical tessellations\\nYear: 2016\\n\\nAbstract: We describe a metric named averaged ratio between complementary profiles to represent the distortion of map projections, and the shape regularity of spherical cells derived from map projections or non-map-projection methods. The properties and statistical characteristics of our metric are investigated. Our metric (1) is a variable of numerical equivalence to both scale component and angular deformation component of Tissot indicatrix, and avoids the invalidation when using Tissot indicatrix and derived differential calculus for evaluating non-map-projection based tessellations where mathematical formulae do not exist (e.g., direct spherical subdivisions), (2) exhibits simplicity (neither differential nor integral calculus) and uniformity in the form of calculations, (3) requires low computational cost, while maintaining high correlation with the results of differential calculus, (4) is a quasi-invariant under rotations, and (5) reflects the distortions of map projections, distortion of spherical cells, and the associated distortions of texels. As an indicator of quantitative evaluation, we investigated typical spherical tessellation methods, some variants of tessellation methods, and map projections. The tessellation methods we evaluated are based on map projections or direct spherical subdivisions. The evaluation involves commonly used Platonic polyhedrons, Catalan polyhedrons, etc. Quantitative analyses based on our metric of shape regularity and an essential metric of area uniformity implied that (1) Uniform Spherical Grids and its variant show good qualities in both area uniformity and shape regularity, and (2) Crusta, Unicube map, and a variant of Unicube map exhibit fairly acceptable degrees of area uniformity and shape regularity.\",\n \"Title: Minimum Modelling Retrospective Cost Adaptive Control Of Uncertain Hammerstein Systems Using Auxiliary Nonlinearities\\nYear: 2014\\n\\nAbstract: We augment retrospective cost adaptive control (RCAC) with auxiliary nonlinearities to address a command-following problem for uncertain Hammerstein systems with possibly non-monotonic input nonlinearities. We assume that only one Markov parameter of the linear plant is known and that the input nonlinearity is uncertain. Auxiliary nonlinearities are used within RCAC to create a globally non-decreasing composite input nonlinearity. The required modelling information for the input nonlinearity includes the intervals of monotonicity as well as values of the nonlinearity that determine overlapping segments of the range of the nonlinearity within each interval of monotonicity.\",\n \"Title: Classification of Alzheimer's Disease Based on Multiple Anatomical Structures' Asymmetric Magnetic Resonance Imaging Feature Selection.\\nYear: 2015\\n\\nAbstract: The quality of magnetic resonance imaging (MRI) features is key to the classification of Alzheimer's disease. However, relevant research has as yet paid little attention to asymmetric MR features. In this paper, the asymmetric MR features of multiple anatomical structures are extracted. The MR feature types include volume feature and several kinds of texture features. Subsequently, the extracted features are selected based on the wrapper feature selection method with chain-like agent genetic algorithm (CAGA) and support vector machine (SVM). Finally, the selected asymmetric MR features are used for classification of Alzheimer's disease. Experimental results show that the extracted features have apparent asymmetrical characteristics. The asymmetric volume feature of single anatomical structure can have better discrimination capability than the whole volume feature of same anatomical structure. Single selected asymmetric MR feature has displayed a superior discrimination capability in regards to three conditions of Alzheimer's disease. The improvement is very apparent compared to before feature selection and the p-value-based feature selection method. In conclusion, this proposed method offer a new kind of feature type and can improve the classification rate for diagnosis of Alzheimer's disease.\",\n \"Title: Environment Factors Monitoring System Based On Can Bus\\nYear: 2016\\n\\nAbstract: In order to solve the greenhouse environmental factors monitoring system wiring is difficult, high cost, single parameter monitoring, lack of flexibility and scalability, which can't meet the requirements of the modern intelligent greenhouse. In this study, a new remote monitoring system was established. In terms of the hardware, the SCM C8051F040 was adopted to collect the environmental parameters such as temperature, humidity, light intensity, CO2 concentration and so on. All data were uploaded via CAN bus and GPRS to the remote host computer. The collected data would be sent to the relevant agricultural management personnel in real time through the GPRS network so that the management could be carried out. Based on Kingview software platform, which was developed to use graphic language and command language system of the PC. Preliminary experimental results show that the system has the correct data transmission, stable operation, good real-time performance and accurately monitor the environmental factors in the greenhouse. The system has the advantages of flexible networking and strong expansibility and intuitive interface, which can well meet the needs of environmental factors monitoring in greenhouse..\",\n \"Title: Vertex-disjoint copies of K1, 3 in K1, r-free graphs.\\nYear: 2016\\n\\nAbstract: Abstract A graph G is said to be K 1 , r -free if G does not contain an induced subgraph isomorphic to K 1 , r . Let k , r be integers with k ≥ 2 , r ≥ 4 . In this paper, we prove that if G is a K 1 , r -free graph of order at least ( k − 1 ) ( 3 r − 2 ) + 1 with δ ( G ) ≥ 3 , then G contains k vertex-disjoint copies of K 1 , 3 . This result shows that Fujita’s conjecture (2008) is true for t = 3 and r ≥ 4 .\",\n \"Title: Efficient Online Surveillance Video Processing Based on Spark Framework.\\nYear: 2016\\n\\nAbstract: In the current surveillance video processing systems, the video processing algorithms and the physical resources are highly coupled, and a video stream is usually used as a basic task scheduling unit. With the expansion of the scale of the system, the traditional systems will cause the large resource fragments that cannot be utilized adequately. In this paper, we propose a novel online surveillance video processing system architecture that combines the distributed Kafka message queue and Spark computing framework. Our system decouples the video stream collection and the video stream processing, and further decouples the video processing tasks and the physical resources. This loosely coupled architecture can quickly recover the failed tasks without data loss for the large-scale video surveillance, and can provide the more scalable distributed computing ability. In addition, a fine-grained online video task management method, which uses the cached video data blocks as the scheduling units, is proposed to increase the resource utilization. Experimental results show that our system has the higher resource utilization and the higher task capacity compared with the traditional systems.\",\n \"Title: Heterogeneous multimodal biomarkers analysis for Alzheimer's disease via Bayesian network.\\nYear: 2016\\n\\nAbstract: By 2050, it is estimated that the number of worldwide Alzheimer's disease (AD) patients will quadruple from the current number of 36 million, while no proven disease-modifying treatments are available. At present, the underlying disease mechanisms remain under investigation, and recent studies suggest that the disease involves multiple etiological pathways. To better understand the disease and develop treatment strategies, a number of ongoing studies including the Alzheimer's Disease Neuroimaging Initiative (ADNI) enroll many study participants and acquire a large number of biomarkers from various modalities including demographic, genotyping, fluid biomarkers, neuroimaging, neuropsychometric test, and clinical assessments. However, a systematic approach that can integrate all the collected data is lacking. The overarching goal of our study is to use machine learning techniques to understand the relationships among different biomarkers and to establish a system-level model that can better describe the interactions among biomarkers and provide superior diagnostic and prognostic information. In this pilot study, we use Bayesian network (BN) to analyze multimodal data from ADNI, including demographics, volumetric MRI, PET, genotypes, and neuropsychometric measurements and demonstrate our approach to have superior prediction accuracy.\",\n \"Title: Vertex-Disjoint Cycles Containing Specified Vertices in a Bipartite Graph.\\nYear: 2016\\n\\nAbstract: The theory of vertex-disjoint cycles of a graph is the generalization of the well-known Hamiltonian cycle theory. In this paper, we prove the following result. Let $$G = (V_{1}, V_{2}; E$$G=(V1,V2źE) be a bipartite graph with $$|V_{1}|= |V_{2}|= n$$|V1|=|V2|=n such that $$n\\\\\\\\ge 2k + 1$$nź2k+1, where k$$\\\\\\\\ge $$ź 1 is an integer. If $$\\\\\\\\sigma _{1,1}(G) \\\\\\\\ge n + k$$ź1,1(G)źn+k, then for any k distinct vertices $$v_{1}, v_{2}, \\\\\\\\ldots , v_{k}$$v1,v2,ź,vk of G, G contains $$k - 1$$k-1 quadrilaterals $$C_{1}, C_{2}, \\\\\\\\ldots , C_{k-1}$$C1,C2,ź,Ck-1 and a path $$P_{k}$$Pk of order 2t, where $$t = n - 2(k - 1)$$t=n-2(k-1), such that all of them are vertex-disjoint and $$v_{i} \\\\\\\\in V(C_{i})$$viźV(Ci) for each $$i \\\\\\\\in \\\\\\\\{1, 2, \\\\\\\\ldots , k - 1\\\\\\\\}, v_{k} \\\\\\\\in V(P_{k})$$iź{1,2,ź,k-1},vkźV(Pk). Using this result we also prove that G contains k vertex-disjoint cycles $$C_{1}, C_{2}, \\\\\\\\ldots , C_{k}$$C1,C2,ź,Ck such that $$v_{i} \\\\\\\\in V(C_{i})$$viźV(Ci) for each $$i \\\\\\\\in \\\\\\\\{1, 2, \\\\\\\\ldots , k\\\\\\\\}$$iź{1,2,ź,k} and there are $$k - 1$$k-1 quadrilaterals in $$\\\\\\\\{C_{1}, C_{2}, \\\\\\\\ldots , C_{k}\\\\\\\\}$${C1,C2,ź,Ck}. Moreover, the degree condition is sharp.\",\n \"Title: Toward a Parallel Turing Machine Model.\\nYear: 2016\\n\\nAbstract: In the field of parallel computing, the late leader Ken Kennedy, has raised a concern in early 1990s: \\\"Is Parallel Computing Dead?\\\" Now, we have witnessed the tremendous momentum of the \\\"second spring\\\" of parallel computing in recent years. But, what lesson should we learn from the history of parallel computing when we are walking out from the bottom state of the field? To this end, this paper examines the disappointing state of the work in parallel Turing machine models in the past 50 years of parallel computing research. Lacking a solid yet intuitive parallel Turing machine model will continue to be a serious challenge. Our paper presents an attempt to address this challenge - by presenting a proposal of a parallel Turing machine model - the PTM model. We also discuss why we start our work in this paper from a parallel Turing machine model instead of other choices.\",\n \"Title: Reconstructing tree trunks by 3D bar filters.\\nYear: 2017\\n\\nAbstract: In this work, we propose an new problem to be solved: reconstruct the 3D points cloud of wild forest from 2D images sequences, locate the tree trunk position and estimate the tree trunk diameters from those reconstructed 3D points and we developed an novel method to solve those three problem once which is able to reconstruct the 3D tree trunk structures, locate the tree trunk and estimate the tree trunk diameters. This is the first work trying to solving those problems jointly. The previous work separate those problem as three sub-tasks: Reconstruct the 3D points from images sets using structure from motion techniques, detect the tree trunk locations and diameters by fitting cylinder models. Unfortunately, the first sub-task is extremely hard due to the poor discriminative image features, strong illumination changes, data corruption caused by the shadows and limited camera view inside the wild forest. The second sub-task requires the first sub-task to provide high quality 3D point cloud. In this work, we found that we are able to take advantage of the vertical structures in the forest to obtain more stable feature matching. Furthermore, with those vertical structure we are able to obtain the tree locations and diameters directly in the process of 3D reconstruction. We demonstrated that our method is able to provide a unified frame work for reconstructing the 3D tree models, estimate the location and trunk size using the 2D images sequences or videos taken in the forest.\",\n \"Title: Parallel Turing Machine, a Proposal.\\nYear: 2017\\n\\nAbstract: We have witnessed the tremendous momentum of the second spring of parallel computing in recent years. But, we should remember the low points of the field more than 20 years ago and review the lesson that has led to the question at that point whether “parallel computing will soon be relegated to the trash heap reserved for promising technologies that never quite make it” in an article entitled “the death of parallel computing” written by the late Ken Kennedy — a prominent leader of parallel computing in the world. Facing the new era of parallel computing, we should learn from the robust history of sequential computation in the past 60 years. We should study the foundation established by the model of Turing machine (1936) and its profound impact in this history. To this end, this paper examines the disappointing state of the work in parallel Turing machine models in the past 50 years of parallel computing research. Lacking a solid yet intuitive parallel Turing machine model will continue to be a serious challenge in the future parallel computing. Our paper presents an attempt to address this challenge by presenting a proposal of a parallel Turing machine model. We also discuss why we start our work in this paper from a parallel Turing machine model instead of other choices.\",\n \"Title: Partial Degree Conditions and Cycle Coverings in Bipartite Graphs.\\nYear: 2017\\n\\nAbstract: Let k be a positive integer. Let G be a graph of order $$n\\\\\\\\ge 3$$n¿3 and W a subset of V(G) with $$|W|\\\\\\\\ge 3k$$|W|¿3k. Wang (J Graph Theory 78:295---304, 2015) proved that if $$d(x)\\\\\\\\ge 2n/3$$d(x)¿2n/3 for each $$x\\\\\\\\in W$$x¿W, then G contains k vertex-disjoint cycles such that each of them contains at least three vertices of W. In this paper, we obtain an analogue result of Wang's Theorem in bipartite graph with the partial degree condition. Let $$G=(V_1,V_2;E)$$G=(V1,V2¿E) be a bipartite graph with $$|V_1|=|V_2|=n$$|V1|=|V2|=n, and let W be a subset of $$V_1$$V1 with $$|W|\\\\\\\\ge 2k$$|W|¿2k, where k is a positive integer. We show that if $$d(x)+d(y)\\\\\\\\ge n+k$$d(x)+d(y)¿n+k for every pair of nonadjacent vertices $$x\\\\\\\\in W, y\\\\\\\\in V_2$$x¿W,y¿V2, then G contains k vertex-disjoint cycles such that each of them contains at least two vertices of W.\",\n \"Title: Disjoint cycles in graphs with distance degree sum conditions.\\nYear: 2017\\n\\nAbstract: In this paper, we prove that for any positive integer k and for any simple graph G of order at least 3k, if d(x)+d(y)≥4k for every pair of vertices x and y of distance 2 in G, then with one exception, G contains k disjoint cycles. This generalizes a former result of Corrádi and Hajnal (1963).\",\n \"Title: Personalized Diagnosis for Alzheimer's Disease.\\nYear: 2017\\n\\nAbstract: Current learning-based methods for the diagnosis of Alzheimer's Disease (AD) rely on training a general classifier aiming to recognize abnormal structural alternations from homogenously distributed dataset deriving from a large population. However, due to diverse disease pathology, the real imaging data in routine clinic practices is highly complex and heterogeneous. Hence, prototype methods commonly performing well in the laboratory cannot achieve expected outcome when applied under the real clinic setting. To address this issue, herein we propose a novel personalized model for AD diagnosis. We customize a subject-specific AD classifier for the new testing data by iteratively reweighting the training data to reveal the latent testing data distribution and refining the classifier based on the weighted training data. Furthermore, to improve estimation of diagnosis result and clinical scores at the individual level, we extend our personalized AD diagnosis model to a joint classification and regression scenario. Our model shows improved performance on classification and regression accuracy when applied on Magnetic Resonance Imaging (MRI) selected from Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Our work pin-points the clinical potential of personalized diagnosis framework in AD.\",\n \"Title: Disjoint cycles in directed graphs.\\nYear: 2018\\n\\nAbstract: Let s and t be two non-negative integers and let D be a directed graph of order n >= 3s + 4t + 3. In this paper we will show that if the minimum sum of in-degree and out-degree delta(D) >= (3n - 3)/2, then D contains s +t + 1 disjoint cycles C-1, ... , Cs+t+1 such that vertical bar CS vertical bar = 3 for each i with 1 <= i <= s, vertical bar C-i vertical bar = 4 for each i with s + 1 <= i <= s + t and vertical bar Cs+t+1 vertical bar = n - 3s - 4t. Furthermore, the degree condition is sharp.\",\n \"Title: On the number of disjoint 4-cycles in regular tournaments.\\nYear: 2018\\n\\nAbstract: In this paper, we prove that for an integer r >= 1, every regular tournament T of degree 3r - 1 contains at least 21/16r - 10/3 disjoint directed 4-cycles. Our result is an improvement of Lichiardopol's theorem when taking q = 4 [Discrete Math. 3 1 0 (2010) 2567-2570]: for given integers q >= 3 and r >= 1, a tournament T with minimum out-degree and in-degree both at least (q - 1) r - 1 contains at least r disjoint directed cycles of length q.\",\n \"Title: Fan-type condition on disjoint cycles in a graph.\\nYear: 2018\\n\\nAbstract: Let k be a positive integer. In this paper, we prove that for a graph G with at least 4k vertices, if max{d(x),d(y)}≥2k for any pair of nonadjacent vertices {x,y}⊆V(G), then G contains k disjoint cycles. This generalizes the results given by Corrá di and Hajnal (1963), Enomoto (1998), and Wang (1999).\",\n \"Title: Longitudinal And Multi-Modal Data Learning For Parkinson'S Disease Diagnosis\\nYear: 2018\\n\\nAbstract: In this paper, we propose a joint regression and classification scheme for Parkinson's disease (PD) diagnosis using longitudinal multi-modal neuroimaging data. Specifically, we devise a new feature selection method imposing three kinds of relational constraints in a unified multi-task feature selection model. These relations (e.g., relations among features, responses, and subjects) are consolidated to represent the similarities among them. The baseline data is utilized to establish the feature selection model exploiting five regression variables (four clinical scores and a clinical label) to jointly select the most discriminative features. Namely, we exploit baseline data to train four regression models for clinical scores prediction and a classification model for discriminating the clinical label in the future time point. Extensive experiments are conducted to demonstrate the effectiveness of the proposed method on the Parkinson's Progression Markers Initiative (PPMI) dataset. The experimental results demonstrate that our proposed method can enhance the performance in clinical scores prediction and class label identification in longitudinal data and outperforms the state-of-art methods as well.\",\n \"Title: Degree sum conditions on two disjoint cycles in graphs.\\nYear: 2018\\n\\nAbstract: Let G be a simple undirected graph on n vertices. A set of subgraphs of G is disjoint if no two of them have any common vertex in G. Suppose that n1,n2 are two integers with n1,n2≥3 and n=n1+n2. We prove that if d(x)+d(y)≥n+4 for any pair of vertices x,y of G with xy∉E(G), then G contains two disjoint cycles of length n1 and n2.\",\n \"Title: The confirmation of a conjecture on disjoint cycles in a graph.\\nYear: 2018\\n\\nAbstract: Let t and k be two integers with t≥5 and k≥2. For a graph G and a vertex x of G, we use dG(x) to denote the degree of x in G. Define σt(G) to be the minimum value of ∑x∈XdG(x), where X is an independent set of G with |X|=t. This paper proves the following conjecture proposed by Gould et al. (2018). If G is a graph of sufficiently large order with σt(G)≥2kt−t+1, then G contains k vertex-disjoint cycles.\",\n \"Title: Dynamic Hyper-Graph Inference Framework for Computer Assisted Diagnosis of Neurodegenerative Diseases.\\nYear: 2019\\n\\nAbstract: Hyper-graph techniques have been widely investigated in computer vision and medical imaging applications, showing superior performance for modeling complex subject-wise relationships and sufficient flexibility to deal with missing data from multi-modal neuroimaging data. Existing hyper-graph methods, however, are inadequate for two reasons. First, representations are generated only from the observ...\",\n \"Title: An improvement of Lichiardopol's theorem on disjoint cycles in tournaments.\\nYear: 2019\\n\\nAbstract: Let k ≥ 1 and q ≥ 3 be integers and let f(q)=(6q2−16q+10)/(3q2−3q−4). In this paper, we prove that if q ≥ 4, then every tournament T with both minimum out-degree and in-degree at least (q−1)k−1 contains at least f(q)k−2q disjoint cycles of length q. We also prove that if q=3 and k ≥ 6, then T contains at least 16k/15−5 disjoint triangles. Our results improve Lichiardopol’s theorem ([Discrete Math. 310 (19) (2010) 2567–2570]): for given integers q ≥ 3 and k ≥ 1, a tournament T with both minimum out-degree and in-degree at least (q−1)k−1 contains at least k disjoint cycles of length q.\",\n \"Title: Vertex-disjoint copies of K1, t in K1, r-free graphs.\\nYear: 2017\\n\\nAbstract: Abstract A graph G is said to be K 1 , r -free if G does not contain an induced subgraph isomorphic to K 1 , r . Let k , r , t be integers with k ≥ 2 and t ≥ 3 . In this paper, we prove that if G is a K 1 , r -free graph of order at least ( k − 1 ) ( t ( r − 1 ) + 1 ) + 1 with δ ( G ) ≥ t and r ≥ 2 t − 1 , then G contains k vertex-disjoint copies of K 1 , t . This result shows that the conjecture in Fujita (2008) is true for r ≥ 2 t − 1 and t ≥ 3 . Furthermore, we obtain a weaker version of Fujita’s conjecture, that is, if G is a K 1 , r -free graph of order at least ( k − 1 ) ( t ( r − 1 ) + 1 + ( t − 1 ) ( t − 2 ) ) + 1 with δ ( G ) ≥ t and r ≥ 6 , then G contains k vertex-disjoint copies of K 1 , t .\",\n \"Title: A low input power charge pump for passive UHF RFID applications\\nYear: 2017\\n\\nAbstract: A novel charge pump with good performance in low-voltage is presented and implemented in UMC 0.18 um process that operates at UHF band of 860MHz to 960MHz. It uses auxiliary charge transfer switches (CTS's) and PMOS charge pump to generate bias voltage for the main charge pump to compensate for the threshold voltage (V\\n<inf xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">th</inf>\\n). The main charge pump is the Dickson rectifiers to double the input voltage. It has been used in an UHF RFID tag to generate supply voltage and occupies the chip area of 250um∗190um. The measurement result shows sensitivity of −10dBm for dc output voltage of 1.1V.\",\n \"Title: A Stereo Visual Obstacle Detection Approach Using Fuzzy Logic And Neural Network In Agriculture\\nYear: 2018\\n\\nAbstract: This paper describes a stereo visual obstacle detection approach using fuzzy logic and neural network in agriculture. Firstly, by training obstacle and non-obstacle colour features with a 6-input neural network, appearance_based method is applied to extract novel regions in monocular image. We apply improved FAST algorithm to extract features, which adapts illumination variation better. At last, we match feature points in the image pairs and obtain the disparity information. The results show that the algorithm is capable of detecting obstacles such as vehicles, humans, trees, plastic bar and other common obstacles in agricultural environment successfully.\",\n \"Title: Monitoring and Analyzing Mountain Glacier Surface Movement Using SAR Data and a Terrestrial Laser Scanner: A Case Study of the Himalayas North Slope Glacier Area.\\nYear: 2019\\n\\nAbstract: The offset tracking technique based on synthetic aperture radar (SAR) image intensity information can estimate glacier displacement even when glacier velocities are high and the time interval between images is long, allowing for the broad use of this technique in glacier velocity monitoring. Terrestrial laser scanners, a non-contact measuring system, can measure the velocity of a glacier even if there are no control points arranged on a glacier. In this study, six COSMO-SkyMed images acquired between 31 July and 22 December 2016 were used to obtain the glacial movements of five glaciers on the northern slope of the central Himalayas using the offset tracking approach. During the period of image acquirement, a terrestrial laser scanner was used, and point clouds of two periods in a small area at the terminus of the Pingcuoliesa Glacier were obtained. By selecting three fixed areas of the point clouds that have similar shapes across two periods, the displacements of the centers of gravity of the selected areas were calculated by using contrast analyses of feature points. Although the overall low-density point clouds data indicate that the glacial surfaces have low albedos relative to the wavelength of the terrestrial laser scanner and the effect of its application is therefore influenced in this research, the registration accuracy of 0.0023 m/d in the non-glacial areas of the scanner's measurements is acceptable, considering the magnitude of 0.072 m/d of the minimum glacial velocity measured by the scanner. The displacements from the point clouds broadly agree with the results of the offset tracking technique in the same area, which provides further evidence of the reliability of the measurements of the SAR data in addition to the analyses of the root mean squared error of the velocity residuals in non-glacial areas. The analysis of the movement of five glaciers in the study area revealed the dynamic behavior of these glacial surfaces across five periods. G089972E28213N Glacier, Pingcuoliesa Glacier and Shimo Glacier show increasing surface movement velocities from the terminus end to the upper part with elevations of 1500 m, 4500 m, and 6400 m, respectively. The maximum velocities on the glacial surface profiles were 31.69 cm/d, 62.40 cm/d, and 42.00 cm/d, respectively. In contrast, the maximum velocity of Shie Glacier, 50.60 cm/d, was observed at the glacier's terminus. For each period, G090138E28210N Glacier exhibited similar velocity values across the surface profile, with a maximum velocity of 39.70 cm/d. The maximum velocities of G089972E28213N Glacier, Pingcuoliesa Glacier, and Shie Glacier occur in the areas where the topography is steepest. In general, glacial surface velocities are higher in the summer than in the winter in this region. With the assistance of a terrestrial laser scanner with optimized wavelengths or other proper ground-based remote sensing instruments, the offset tracking technique based on high-resolution satellite SAR data should provide more reliable and detailed information for local and even single glacial surface displacement monitoring.\",\n \"Title: Concrete Crack Detection and Monitoring Using a Capacitive Dense Sensor Array.\\nYear: 2019\\n\\nAbstract: Cracks in concrete structures can be indicators of important damage and may significantly affect durability. Their timely identification can be used to ensure structural safety and guide on-time maintenance operations. Structural health monitoring solutions, such as strain gauges and fiber optics systems, have been proposed for the automatic monitoring of such cracks. However, these solutions become economically difficult to deploy when the surface under investigation is very large. This paper proposes to leverage a novel sensing skin for monitoring cracks in concrete structures. This sensing skin is constituted of a flexible electronic termed soft elastomeric capacitor, which detects a change in strain through changes in measured capacitance. The SEC is a low-cost, durable, and robust sensing technology that has previously been studied for the monitoring of fatigue cracks in steel components. In this study, the sensing skin is introduced and preliminary validation results on a small-scale reinforced concrete beam are presented. The technology is verified on a full-scale post-tensioned concrete beam. Results show that the sensing skin is capable of detecting, localizing, and quantifying cracks that formed in both the reinforced and post-tensioned concrete specimens.\",\n \"Title: A novel design of experiment algorithm using improved evolutionary multi-objective optimization strategy\\nYear: 2021\\n\\nAbstract: The paper aims to propose an intelligent design of experiment (DOE) algorithm using an improved evolutionary multi-objective optimization approach. Adaptive evolutionary strategies are embedded in the algorithm to support the design of simulation test schemes with multiple factors whose levels are same or different. Comparative results with several existing DOE algorithms show better sampling capacity and fine sampling efficiency of the proposed algorithm. Application effects of a complex flight simulator indicate the algorithm a wide technological prospect of serving well certain complex systems.\",\n \"Title: Pixel-Level Fatigue Crack Segmentation In Large-Scale Images Of Steel Structures Using An Encoder-Decoder Network\\nYear: 2021\\n\\nAbstract: Fatigue cracks are critical types of damage in steel structures due to repeated loads and distortion effects. Fatigue crack growth may lead to further structural failure and even induce collapse. Efficient and timely fatigue crack detection and segmentation can support condition assessment, asset maintenance, and management of existing structures and prevent the early permit post and improve life cycles. In current research and engineering practices, visual inspection is the most widely implemented approach for fatigue crack inspection. However, the inspection accuracy of this method highly relies on the subjective judgment of the inspectors. Furthermore, it needs large amounts of cost, time, and labor force. Non-destructive testing methods can provide accurate detection results, but the cost is very high. To overcome the limitations of current fatigue crack detection methods, this study presents a pixel-level fatigue crack segmentation framework for large-scale images with complicated backgrounds taken from steel structures by using an encoder-decoder network, which is modified from the U-net structure. To effectively train and test the images with large resolutions such as 4928 x 3264 pixels or larger, the large images were cropped into small images for training and testing. The final segmentation results of the original images are obtained by assembling the segment results in the small images. Additionally, image post-processing including opening and closing operations were implemented to reduce the noises in the segmentation maps. The proposed method achieved an acceptable accuracy of automatic fatigue crack segmentation in terms of average intersection over union (mIOU). A comparative study with an FCN model that implements ResNet34 as backbone indicates that the proposed method using U-net could give better fatigue crack segmentation performance with fewer training epochs and simpler model structure. Furthermore, this study also provides helpful considerations and recommendations for researchers and practitioners in civil infrastructure engineering to apply image-based fatigue crack detection.\",\n \"Title: Vertex-Disjoint Stars In K-1,K-R-Free Graphs\\nYear: 2021\\n\\nAbstract: A graph G is said to be K-1,K-r-free if G does not contain an induced subgraph isomorphic to K-1,K-r. Let k, r, t be integers with k >= 2, r >= 3 and t >= 2. Fujita (2008) conjectured that if G is a K-1,K-r-free graph of order at least (k - 1)(t(r - 1) + 1) + 1 with minimum degree at least t, then G contains k disjoint copies of K-1,K-t. In this paper, we show that this conjecture is true for the case r > t >= 3 and for the case r = t = 4, and we also show that this conjecture is true if vertical bar V(G)vertical bar >= (k - 1)(t(2) - 2) + 1 and t >= r >= 4. (C) 2021 Elsevier B.V. All rights reserved.\",\n \"Title: Regression and Evaluation on a Forward Interpolated Version of the Great Circle Arcs-Based Distortion Metric of Map Projections\\nYear: 2021\\n\\nAbstract: We studied the numerical approximation problem of distortion in map projections. Most widely used differential methods calculate area distortion and maximum angular distortion using partial derivatives of forward equations of map projections. However, in certain map projections, partial derivatives are difficult to calculate because of the complicated forms of forward equations, e.g., equations with iterations, integrations, or multi-way branches. As an alternative, the spherical great circle arcs-based metric employs the inverse equations of map projections to transform sample points from the projection plane to the spherical surface, and then calculates a differential-independent distortion metric for the map projections. We introduce a novel forward interpolated version of the previous spherical great circle arcs-based metric, solely dependent on the forward equations of map projections. In our proposed numerical solution, a rational function-based regression is also devised and applied to our metric to obtain an approximate metric of angular distortion. The statistical and graphical results indicate that the errors of the proposed metric are fairly low, and a good numerical estimation with high correlation to the differential-based metric can be achieved.\",\n \"Title: How to promote COVID-19 pandemic prevention and control: A game theory analysis\\nYear: 2021\\n\\nAbstract: The outbreak of the COVID-19 (Corona Virus Disease 2019) has been becoming the most serious public health event in the world, threatening the health of hundreds of millions of people. The anti-pandemic policies mostly aim to prevent the spread at domestic and the import from abroad. In this paper, we discuss the issue of individual protection measures and customs quarantine strategy based on game theory. First, we develop a 2*2 Bayesian model and show that individual protection decisions depend on the size of excess payoff of taking protective measures (EPP). EPP is affected by the protection cost, the protective efficiency, the risk exposure and the information disclosure in this model. Then, we describe a repeated game between customs and airlines, and discuss the ideal strategy for customs to prevent the virus input. It comes out that a punishment mechanism for an airline is meaningful to prevent the import of the virus only if the discount rate of the airline is greater than the threshold. The threshold is positively correlated with the detection cost, and it is negatively correlated with the revenue of the airline and the testing reliability. We can also benefit from establishing a credit mechanism to give airlines that deviate from cooperation an opportunity to re-cooperate, especially for those in low risk areas. This study provides theoretical support for some government policies to prevent COVID-19, and underscores the significance of considering individual and organizational decision-making in health policy making.\",\n \"Title: Image-Based Angular Distortion Metric of Map Projections by Using Surface Fitting for Noise Reduction\\nYear: 2022\\n\\nAbstract: Measuring, analyzing, reducing, and optimizing distortions in map projections is important in cartography. In this study, we introduced a novel image-based angular distortion metric based on the previous spherical great circle arcs-based metric. Images with predefined patterns were used to generate distorted images using mapping software. The generated distorted images with known patterns were then exploited to calculate the proposed angular distortion metric. The mapping software performed the underlying transformation of map projections. Therefore, there was no direct explicit dependence on the forward equations of the map projections in our proposed metric. However, there were fairly large computation errors in the ordinary image-based approach without special correction. To reduce the error, we introduced surface-fitting-based noise reduction in our approach. We established and solved systems of linear equations based on bivariate polynomial functions in the process of noise reduction. Sufficient experiments were made to validate the proposed image-based metric and the accompanying noise reduction approach. In the experiment, the NASA G.Projector was employed as the mapping software for evaluating more than 200 map projections. Experimental results demonstrated that the proposed image-based approach and surface fitting-based noise reduction are feasible and practical for the evaluation of the angular distortion of map projections.\",\n \"Title: <p>Disjoint cycles and 2-factors with Fan-type condition in a graph</p>\\nYear: 2022\\n\\nAbstract: Let k be a positive integer. For a graph G, let sigma(2)(1) (G) be the minimum value of max{d(x), d(y)} for any pair of nonadjacent vertices x and y. Corr & aacute;di and Hajnal proved that every graph G of order n >=& nbsp;3k with delta(G) >=& nbsp;2k contains k disjoint cycles. In this paper, we generalize this theorem by proving that, for a graph G of order at least 3k + 2, if sigma(2)(1)(G) >=& nbsp;2k, then G contains k disjoint cycles. The bound of order is sharp. Based on this result, we show that if G is a 2-connected graph of order at least 3k + 5 with sigma(2)(1)(G) >=& nbsp;max{n/2, 2k + 2}, then G contains a 2-factor with exactly k disjoint cycles, which improves the theorem of Brandt et al. (1997) [2]. (C)& nbsp;2021 Elsevier B.V. All rights reserved.\",\n \"Title: Cycle Extendability in Extended Tournaments\\nYear: 2022\\n\\nAbstract: An extended tournament is an orientation of a \\n \\n \\n \\n $$c (\\\\ge 2)$$\\n \\n -partite complete graph such that if there is one arc between two partite sets, say from \\n \\n \\n \\n $$V_i$$\\n \\n to \\n \\n \\n \\n $$V_j$$\\n \\n , then there is an arc from every vertex in \\n \\n \\n \\n $$V_i$$\\n \\n to every vertex in \\n \\n \\n \\n $$V_j$$\\n \\n . In this paper, we show the following. Let T be an extended tournament with \\n \\n \\n \\n $$c\\\\ge 4$$\\n \\n partite sets. For every non-Hamiltonian cycle C in T there is a cycle \\n \\n \\n \\n $$C^\\\\prime $$\\n \\n such that \\n \\n \\n \\n $$V (C) \\\\subset V (C^\\\\prime )$$\\n \\n and \\n \\n \\n \\n $$|C^\\\\prime |\\\\le |C| + 2$$\\n \\n if and only if T is Hamiltonian. Moreover, we give two examples to prove that the condition \\n \\n \\n \\n $$c\\\\ge 4$$\\n \\n is needed, and there exists an infinite family of extended tournaments which are Hamiltonian but have no cycle \\n \\n \\n \\n $$C^\\\\prime $$\\n \\n such that \\n \\n \\n \\n $$V (C) \\\\subset V (C^\\\\prime )$$\\n \\n and \\n \\n \\n \\n $$|C^\\\\prime |= |C| + 1$$\\n \\n for a non-Hamiltonian cycle C in T.\",\n \"Title: A hybrid crossover multi-agent multi-objective evolutionary algorithm and its application in microgrid operation optimization\\nYear: 2022\\n\\nAbstract: The power generation industry needs to adopt renewable energy so as to reduce the utilization of fossil energy and pollution emission. In renewable energy power generation, microgrid operation optimization needs to consider multiple objectives such as economy and environmental protection, which is a multi-objective optimization problem Aiming at the multi-objective optimization problem, based on the Pareto optimal concept, a hybrid crossover multi-agent multi-objective evolutionary algorithm is proposed and applied to the multi-objective optimization problem of microgrid systems, in which the economical cost and environmental protection are considered. The simulation results under three operating conditions show that compared with the classical NSGA-66 algorithm, the proposed algorithm can obtain higher quality Pareto optimal solution in a shorter time. The efficiency of the proposed algorithm in this problem is higher than that of the classical NSGA-66 algorithm. It can provide a higher quality solution for the optimal operation of a microgrid.\",\n \"Title: MCS Analysis for 5G-NR V2X Sidelink Broadcast Communication\\nYear: 2022\\n\\nAbstract: Leveraging Modulation and Coding Schemes (MCS) in 5G New Radio (NR) Sidelink represents one key strategy to provide sufficient capacity required by future 5G for Vehicle-to-Everything (V2X) services for intelligent vehicles. Early studies either directly adopt the previously optimised QPSK 1/2 by 802.11p/C-V2X or suggest an optimal MCS value under a particular context. In this paper, we identify a MCS value optimal under any context, by evaluating the impact of MCS on V2X broadcast communication considering multiple varying parameters (e.g. variable packet size, transmit rate or density) representative of different 5G V2X services.\",\n \"Title: Multi-Source Time Series Remote Sensing Feature Selection and Urban Forest Extraction Based on Improved Artificial Bee Colony\\nYear: 2022\\n\\nAbstract: Urban forests maintain the ecological balance of cities and are significant in promoting the sustainable development of cities. Therefore, using advanced remote sensing technology to accurately extract forest green space in the city and monitor its change in real-time is very important. Taking Nanjing as the study area, this research extracted 55 vegetation phenological features from Sentinel-2A time series images and formed a feature set containing 81 parameters together with 26 features, including polarimetric- and texture-related information extracted from dual-polarization Sentinel-1A data. On the basis of the improved ABC (ABC-LIBSVM) feature selection method, the optimal feature subset was selected, and the forest coverage areas in the study area were accurately described. To verify the feasibility of the improved feature selection method and explore the potential for the development of multi-source time series remote sensing for urban forest feature extraction, this paper also used the random forest classification model to classify four different feature sets. The results revealed that the classification accuracy based on the feature set obtained by the ABC-LIBSVM algorithm was the highest, with an overall accuracy of 86.80% and a kappa coefficient of 0.8145. The producer accuracy and user accuracy of the urban forest were 93.21% and 82.45%, respectively. Furthermore, by combining the multi-source time series Sentinel-2A optical images with Sentinel-1A dual-polarization SAR images, urban forests can be distinguished from the perspective of phenology, and polarimetric- and texture-related features can contribute to the accurate identification of forests.\",\n \"Title: A Federated Learning Backdoor Attack Defense Method Based on Dual Attention Mechanism\\nYear: 2022\\n\\nAbstract: As a distributed machine learning paradigm, federated learning allows clients to collaboratively train models without sharing their private data, effectively solving data privacy issues in edge computing scenarios. However, recent studies have shown that neural network models in federated learning are vulnerable to backdoor attacks, which make the global model give wrong inference results in a high-confidence manner, such as recognizing stop signs as speed limit signs in the image classification task. This will have serious consequences. Aiming at the problem that the existing federated learning defense methods take a long time to compute and cannot destroy the matching relationship between triggers and backdoors, a federated learning backdoor attack defense based on dual attention mechanism (FDDAM) is proposed. The model weights are dynamically adjusted during training process, no additional models are required, and the calculation time is shorter. First, in order for the model to ignore triggers, the enhancement on image semantics is performed and then build channel attention map. Second, in order to destroy the matching relationship between triggers and backdoors, a feature map space transformation network is constructed. Finally, in order to improve the defense success rate, the channel attention map and the spatial attention map are weighted to construct a dual attention network. Experiments with FDDAM on image classification datasets show an average increase of 1.68% and 3.11% in model accuracy and defense success rate, and an average reduction of 1.85 times in computation time compared to the benchmark method.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":70,"string":"70"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":73,"string":"73"}}},{"rowIdx":74,"cells":{"question_id":{"kind":"string","value":"Ravi Prakash"},"question":{"kind":"string","value":"Generate an abstract for the title \"Quantitative Biochemical Assay on a Surface Microfluidic Device\" using the following items: 1. Quantitative analysis\n2. Microfluidic systems\n3. Nucleic acid detection\n4. DEP-based surface system\n5. On-chip mixing"},"answer":{"kind":"string","value":"Quantitative analysis of chemical and biochemical molecules is an important requirement in many biochemical assays and can be a challenging task in microfluidic systems due to the smaller sample volumes. In the present study, we report on the detection and quantification of nucleic acid samples contained in nanoliter (nL) and picoliter (pL) droplets, formed by employing a DEP based surface microfluidic system. This surface microfluidic system utilizes non-uniform AC electric fields for dispensing multiple, nanoliter (and picoliter) sized aliquots of samples and reagents, which can furthermore be individually addressed, transported and mixed on-chip in a controlled and parallel fashion. Quantification of dsDNA samples is carried out using a fluorescence based Quant-IT(TM) PicoGreen(R) assay, performed on the surface microfluidic chip, while the low-level fluorescence emissions are quantified using a photo-multiplier tube. Our findings show that sample DNA concentrations remain uniform across the dispensed droplets, although the volume of droplets can be varied as per requirements. Experimental results furthermore prove that our DEP based and electric field assisted on-chip mixing methodology is at par with conventional mixing strategies such as vortexing, stirring etc. and more readily achieved compared to conventional closed channel microfluidic systems."},"correct_answer":{"kind":"string","value":"Quantitative analysis of chemical and biochemical molecules is an important requirement in many biochemical assays and can be a challenging task in microfluidic systems due to the smaller sample volumes. In the present study, we report on the detection and quantification of nucleic acid samples contained in nanoliter (nL) and picoliter (pL) droplets, formed by employing a DEP based surface microfluidic system. This surface microfluidic system utilizes non-uniform AC electric fields for dispensing multiple, nanoliter (and picoliter) sized aliquots of samples and reagents, which can furthermore be individually addressed, transported and mixed on-chip in a controlled and parallel fashion. Quantification of dsDNA samples is carried out using a fluorescence based Quant-IT(TM) PicoGreen(R) assay, performed on the surface microfluidic chip, while the low-level fluorescence emissions are quantified using a photo-multiplier tube. Our findings show that sample DNA concentrations remain uniform across the dispensed droplets, although the volume of droplets can be varied as per requirements. Experimental results furthermore prove that our DEP based and electric field assisted on-chip mixing methodology is at par with conventional mixing strategies such as vortexing, stirring etc. and more readily achieved compared to conventional closed channel microfluidic systems."},"documents":{"kind":"list like","value":["Title: A Distributed Protocol for Dynamic Address Assignment in Mobile Ad Hoc Networks\nYear: 2006\n\nAbstract: A Mobile Ad hoc NETwork (MANET) is a group of mobile nodes that form a multihop wireless network. The topology of the network can change randomly due to unpredictable mobility of nodes and propagation characteristics. Previously, it was assumed that the nodes in the network were assigned IP addresses a priori. This may not be feasible as nodes can enter and leave the network dynamically. A dynamic IP address assignment protocol like DHCP requires centralized servers that may not be present in MANETs. Hence, we propose a distributed protocol for dynamic IP address assignment to nodes in MANETs. The proposed solution guarantees unique IP address assignment under a variety of network conditions including message losses, network partitioning and merging. Simulation results show that the protocol incurs low latency and communication overhead for an IP address assignment.","Title: MAC-Layer Scheduling in Cognitive Radio based Multi-Hop Wireless Networks\nYear: 2006\n\nAbstract: Cognitive radios CR have the ability to dynamically adapt to local spectrum availability. In a multi-hop wireless network comprised of CR-enabled devices, Medium Access Control (MAC) layer scheduling for data communication involves assignment of timeslots and channels to either links or nodes in the network. The number of channels available and the channel identities vary from one node to another within the CR network. This is in contrast to the existing use of multiple channels where all the nodes have the same set of channels available (for example in IEEE 802.11 networks). In this paper, we present an Integer Linear Programming (ILP) formulation for the MAC-layer scheduling problem and find an optimal schedule. We also propose a simple and efficient distributed heuristic for MAC-layer scheduling. Simulation results indicate that the proposed distributed heuristic provides near optimal schedule.","Title: Improving the Performance of Hybrid Wireless Mesh Protocol\nYear: 2012\n\nAbstract: Recently, IEEE 802.11s has been ratified as an amendment to the IEEE 802.11 standard. It adds the ability to establish a wireless mesh network. The amendment makes provisions for a routing protocol called Hybrid Wireless Mesh Protocol(HWMP). In this paper we study the impact of asymmetric bidirectionallinks on the performance of HWMP. We show through experiments using real hardware on a test bed and the open80211simplementation of HWMP that such links significantly impact the performance of the protocol. We describe in detail the cause of decline in performance and attribute it to implementation issues and more importantly the inadequacy of the routing metric. Moreover, we propose solutions to the identified problems, implement those solutions by making modifications to the Linux kernel mac80211 stack and show the achieved performance gains through detailed experiments.","Title: A Biased Random Walk Routing Protocol for Wireless Sensor Networks: The Lukewarm Potato Protocol\nYear: 2010\n\nAbstract: Low-latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper, we first study the lowest latency path problem, i.e., the characteristics of a path with minimum delay that connects a source node to the sink under random duty cycling nodes. Then, we propose a forwarding protocol based on biased random walks, where nodes only use local information about neighbors and their next active period to make forwarding decisions. We refer to this as lukewarm potato forwarding. Our analytical model and simulation experiments show that it is possible to reduce path latency without significantly increasing the number of transmissions (energy efficiency) needed to deliver the message to the destination. In particular, although deviating from the shortest path requires additional transmissions, and hence, higher energy consumption, this increase is compensated by a lighter duty cycle. Our experiments show that, overall, we can save up to 15 percent of energy while obtaining the same data delivery delay as shortest path routing. Additionally, the proposed solution is tunable. By changing the value of just one threshold parameter, it can be tuned to operate anywhere in the continuum from hot potato/random walk forwarding protocol to a deterministic shortest path forwarding protocol.","Title: Designing communication strategies for hetereogeneous parallel systems\nYear: 1998\n\nAbstract: This paper investigates communication strategies for interconnecting heterogeneous parallelsystems. As the speed of processors and parallel systems keep on increasing over the years, electronicinterconnections like HIPPI and FDDI are reaching their limit to provide heterogeneousparallel computing environment. This paper explores the suitability of the emerging passivestar-coupled optical interconnection using wavelength division multiplexing as the system interconnectto provide high...","Title: Issues in Message Passing for a Tele-immersive Experience\nYear: 2001\n\nAbstract: Tele-immersion is one of the applications being developed in conjunction with the Internet-2 initiative.Most of the research in this area has focused on issues pertaining to image acquisition and display,tracking technologies, robotics,haptics,etc.In order to maintain consistency of a tele-immersive experience one also needs to develop a suit of solutions that will ensure proper coordination between the participants.This will require protocols for real-time causal delivery of messages while maintaining the privacy of conversations and preventing forgery of message contents.This paper discusses these issues while considering a tele-immersive environment as a distributed message passing system.","Title: A Dynamic Approach To Location Management In Mobile Computing Systems\nYear: 1996\n\nAbstract: Managing location information of mobile nodes is an important issue in mobile computing systems. There is a trade-off between location update effort (when a node moves) and node finding effort. In this paper we present a dynamic location management strategy that has the following features (i) all location servers need not maintain location information about every mobile node, (ii) a coterie based approach is adopted for location update and find, (iii) every node move does not result in location updates, (iv) location updates are done at a subset of location servers, (v) a subset of location servers are queried when a mobile node is to be located, (vi) the set of location servers, corresponding to a mobile node, for location update and find operations is dynamic, (vii) the dynamic nature of these sets helps alleviate situations of heavy burden on some location servers, when a large number of mobile nodes are concentrated in a small geographical area. Thus, location management is done efficiently, and responsibility is shared fairly among location servers.","Title: Slotted-FIFO Communcation for Asynchronous Distributed Systems\nYear: 1998\n\nAbstract: Communication protocols designed for database applications are not necessarily suitable for other applications, like multimedia communication, due to the former's requirement of reliable and ordered communication, and the latter's ability to withstand occasional losses and misordering of messages as long as real-time communication can be supported. This paper presents the slotted-FIFO communicatio...","Title: Lukewarm potato forwarding: a biased random walk routing protocol for wireless sensor networks\nYear: 2009\n\nAbstract: Low latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper we firstly study the lowest latency path problem, i.e., the characteristics of path with minim delay that connect a source node to the sink under random duty cycling nodes. Then, we propose a forwarding protocol based on biased random walks, where nodes only use local information about neighbors and their next active period to make forwarding decisions. We refer to this as lukewarm potato forwarding. Our analytical model and simulation experiments show that it is possible to reduce path latency without significantly increasing the number of transmissions (energy efficiency) needed to deliver the message to the destination. Additionally, the proposed solution is tunable. By changing the value of just one threshold parameter it can be tuned to operate anywhere in the continuum from hot potato/random walk forwarding protocol to a deterministic shortest path forwarding protocol.","Title: Ieee 802.11 Dcf Performance Evaluation Using One-Dimensional Discrete Time Chains\nYear: 2006\n\nAbstract: Previously proposed analytical studies for IEEE 802.11 Distributed Coordination Function model the behavior of a wireless station operating under saturation conditions as a two-dimensional discrete time Markov chain. In this document, we show that the two-dimensional chain can be partitioned into two one-dimensional chains. Such a partitioning not only simplifies the analysis, but also significantly reduces the number of state variables.","Title: FAROES: Fairness And Reliability using Overlay Expenseless Set-out for Duty-cycle Optimization in WSN\nYear: 2009\n\nAbstract: Wireless sensor networks (WSNs) consist of a large number of enti- ties that collaborate in order to provide given services. Unfortunately, due to their tiny size, these entities cannot be equipped with a long-life battery. In order to minimize overall energy consumption and maximize the lifetime of the network a widely accepted approach is to implement a duty cycle. Specifically, in order to save battery life, sensors are not active all the time, and switch off their capabili- ties according to a specific schedule. In this paper, we propose a generic method to schedule these duty-cycles, taking into account two important challenges in WSNs : strong reliability of the net- work and fairness between sensors. To achieve these aims, we ensure reliability by deploying several k-connected overlays, which became active one after the other. The fairness rule is ensured by spreading the sensors into overlay accord- ing to specific characteristics as energy consumption, network density, etc. We then propose different heuristics and probability models to achieve our outcome, and finally evaluate them through simulation experiments.","Title: Information Dissemination in Partitionable Mobile Ad Hoc Networks\nYear: 1999\n\nAbstract: Ad hoc wireless networks have no wired component, and may have unpredictable mobility pattern. Such networks can get partitioned and reconnected several times. One possible approach for information dissemination in such networks is to replicate information at multiple nodes acting as repositories, and employ quorum based strategies to update and query information. We propose three such strategies that also use local knowledge about the reachability of repositories to judiciously select quorums. The primary goal is high availability of information in the face of network partitioning. We also consider four policies to determine the appropriate time to perform updates. Experimental results indicate that a hybrid information management strategy and an absolute connectivity-based update trigger policy are most suited for partitionable ad-hoc networks.","Title: An adaptive causal ordering algorithm suited to mobile computing environments\nYear: 1997\n\nAbstract: Causal message ordering is required for several distributed applications. In order topreserve causal ordering, only direct dependency information between messages, withrespect to the destination process(es), need be sent with each message. By eliminatingother kinds of control information from the messages, the communication overheadscan be significantly reduced. In this paper we present an algorithm that uses thisknowledge to efficiently enforce causal ordering of messages. The proposed...","Title: Variable Power Broadcasting In Ad Hoc Networks\nYear: 2006\n\nAbstract: Network wide broadcast is a frequently used operation in ad hoc networks and consumes significant amount of energy. Reducing the overall power consumption is extremely important in increasing the longevity of ad hoc networks. As a result, developing energy efficient broadcast operations becomes an important issue in ad hoc networks. In this paper, we propose an adaptive power broadcast algorithm that uses localized information in ad hoc networks. Our algorithm uses a novel technique to improve energy efficiency in network wide broadcast. Our simulation based comparisons show the superiority of our algorithm compared to other approaches.","Title: Broadcast with Time and Causality Constraints for Multimedia Applications\nYear: 1996\n\nAbstract: : \\Delta-causal ordering is a communication abstraction designed for distributed applicationswhose messages (i) have to be delivered according to causal ordering and (ii) have a limited lifetimeafter which their data can no longer be used by the application. Example of such applications are:multimedia real-time collaborative applications and groupware real-time applications. For such applications,the broadcasting of information is of primary importance. In this paper, we propose a simple...","Title: ASSERT: Advanced wireleSS Environment Research Testbed\nYear: 2009\n\nAbstract: Software simulation has often been used to evaluate proposed protocols for wireless devices. Simulation allows for rapid development and testing, but does not provide a realistic RF environment. To compensate for this, field experiments are performed. However, problems encountered during field experiments can be difficult to locate and correcting problems on-site can be time-consuming. Emulations attempt to provide the advantages of simulation and field experiments without the suffering the disadvantages of both. This demo provides an overview of the hardware, software, and emulation capabilities of ASSERT, an emulation testbed.","Title: Low-Cost Checkpointing and Failure Recovery in Mobile Computing Systems\nYear: 1996\n\nAbstract: A mobile computing system consists of mobile and stationary nodes, connected to each other by a communication network. The presence of mobile nodes in the system places constraints on the permissible energy consumption and available communication bandwidth. To minimize the lost computation during recovery from node failures, periodic collection of a consistent snapshot of the system (checkpoint) is required. Locating mobile nodes contributes to the checkpointing and recovery costs. Synchronous snapshot collection algorithms, designed for static networks, either force every node in the system to take a new local snapshot, or block the underlying computation during snapshot collection. Hence, they are not suitable for mobile computing systems. If nodes take their local checkpoints independently in an uncoordinated manner, each node may have to store multiple local checkpoints in stable storage. This is not suitable for mobile nodes as they have small memory. This paper presents a synchronous snapshot collection algorithm for mobile systems that neither forces every node to take a local snapshot, nor blocks the underlying computation during snapshot collection. If a node initiates snapshot collection, local snapshots of only those nodes that have directly or transitively affected the initiator since their last snapshots need to be taken. We prove that the global snapshot collection terminates within a finite time of its invocation and the collected global snapshot is consistent. We also propose a minimal rollback/recovery algorithm in which the computation at a node is rolled back only if it depends on operations that have been undone due to the failure of node(s). Both the algorithms have low communication and storage overheads and meet the low energy consumption and low bandwidth constraints of mobile computing systems.","Title: Effects of link stability and directionality of motion on routing algorithms in MANETs.\nYear: 2000\n\nAbstract: Most of the routing protocols proposed for Mobile Ad Hoc Networks (MANETs) rely on caching routes to increase the speed and reduce the cost of route discovery. These protocols assume high path stability between the mobile nodes in the network. This paper studies persistence of paths under various mobility patterns and network sizes. The conclusions drawn from this study enable us to determine the effectiveness of caching and also to suggest suitable caching durations. The simulation experiments indicate that path persistence declines with increasing network density and diameter. Restricting the motion of nodes increases path persistence while also increasing network partitioning. Hence, caching of routes in mobile ad hoc networks appears to have serious scalability problems.","Title: Adaptive Ieee 802.11 Dcf Scheme With Knowledge-Based Backoff\nYear: 2005\n\nAbstract: The IEEE 802.11 Distributed Coordination Function (DCF) does not require tire presence of a central controller (access point). It is based on carrier sense multiple access with collision avoidance and binary exponential backoff. While performing the backoff procedure, nodes monitor the state of tire medium and.f counter when channel is sensed busy. Under freeze backof saturation conditions, theoretical throughput limit achievable by the DCF scheme was presented in [4]. It was shown that DCF operated very far from the theoretical limit due to increased time for negotiating channel access. An enhancement to the DCF scheme so that it achieves tire theoretical limit was also presented. However, tire solution requires tire knowledge of number of nodes contending for the shared medium, which is difficult to predict in the absence of a central controller. Slow contention window decrease (SD) scheme [9] modifies the backoff procedure in DCF to improve its performance under saturation conditions. However, the SD scheme uses only a part of tire available channel state information.Additional knowledge available to nodes about tire number of collisions and freezes experienced in the recent past can be used to determine contention for tire medium more accurately. In this paper, we present an adaptive DCF (ADCF) scheme that adapts its backoff procedure based on such knowledge. Through simulation experiments, we compare tire performance of ADCF with that qf DCF and SD. Under saturation conditions, we observe that both DCF and SD operate far from the theoretical throughput limit due to their inabilily to negotiate contention for the medium quickly. By making use of the additional knowledge, the proposed ADCF scheme operates closer to the theoretical limit. For example, when DCF and SD respectively operate 35% and 20% below tire theoretical throughput limit, ADCF operates only 10% below the theoretical limit. Moreover, by recording the channel state information observed during the recent past, ADCF is also able to batter respond to tire variations in the offered traffic.","Title: Variable power broadcast using local information in ad hoc networks\nYear: 2008\n\nAbstract: Network wide broadcast is a frequently used operation in ad hoc networks. Developing energy efficient protocols to reduce the overall energy expenditure in network wide broadcast can contribute toward increasing the longevity of ad hoc networks. Most of the existing work in energy efficient broadcast protocols use either a fixed transmission power model or assume global knowledge of the entire network at each node. Variable power broadcast with local knowledge has recently been proposed as a promising alternative approach for network wide broadcast in ad hoc networks. In this paper, we present a novel approach, called INOP, for network wide broadcast. INOP is a variable power broadcast approach that uses local (two-hop neighborhood) information. INOP utilizes a novel technique for determining the transmission power level at each transmitting node. We also propose two alternative methods to cover the nodes that are not covered by the transmission of the source or a retransmitting node. Our simulation based evaluations show that, compared to other approaches, INOP achieves better results in terms of energy efficiency, and competes with and exceeds other approaches in terms of a number of other performance metrics including traffic overhead, coverage, and convergence time. Based on these results, we can conclude that INOP improves the current state-of-the-art approaches for energy efficient broadcast in ad hoc networks.","Title: Continuous Active Phase Shifter Design and Analysis for Millimeter-Wave Circuits.\nYear: 2013\n\nAbstract: This brief presents a continuous active phase shifter for millimeter-wave phased-array transceivers. Having an all-pass network frequency response, the proposed phase shifter provides continuous insertion phase control and nearly constant insertion loss regardless of the insertion phase variation. A complete analysis for the phase shifter is provided along with circuit measurement results. The pha...","Title: \"RF in the Jungle\": effect of environment assumptions on wireless experiment repeatability\nYear: 2009\n\nAbstract: Most researchers conduct wireless networking experiments in their laboratory or similar indoor environments. Such environments are veritable RF jungles, especially when we consider the ISM bands. In this paper we examine and test several common explicit and implicit assumptions that researchers tend to make about the wireless environment. Although these assumptions are acknowledged by most researchers, the extent of their impact is often underestimated. We find that because the environment is always in flux, it is almost impossible to reproduce the results of an experiment. Hence, there is a high risk of misinterpreting the data obtained from such experiments. Through this paper we try to caution experimenters against such risky assumptions when they venture into the RF jungle. After a successful proof-of-concept experiment, we advocate the use of wireless networking testbeds that provide experimenters better control over the RF environment by using coaxial cables, programmable attenuators and power dividers/combiners.","Title: Parallel and Gaussian frequency hopping for dynamic coexistence in the unlicensed band\nYear: 2011\n\nAbstract: With the surge of short-range wireless applications, more networks are being deployed in the unlicensed radio band. The challenge that emerges is to accommodate these networks without breaching current rules and regulations on frequency usage. This paper studies the coexistence of several independent and dynamic wireless networks using the frequency hopping technique. We propose a novel hopping scheme that minimizes mutual interference and allows more networks to collocate effectively, but does not violate restrictions imposed by the Federal Communications Commission (FCC) regarding frequency constraint (related to the minimum number of frequencies in a hopping set) and time constraint (related to the maximum duration of using a particular frequency). The coexisting networks follow the Gaussian distribution in choosing transmission frequencies from parallel hopping spaces without the overhead of extra message exchange among networks. Simulation results on key metrics such as channel collision rate, goodput, and fairness in channel usage are presented to establish the viability of the proposed scheme in comparison with other contemporary approaches. Copyright © 2011 John Wiley & Sons, Ltd. (This work has been supported in part by the National Science Foundation (NSF) under grant no. CNS-0435105. A preliminary and partial presentation of this study has appeared in the proceedings of IEEE International Conference on Communications (ICC), Dresden, Germany, June 2009.)","Title: Architecture for Group Communication in Mobile Systems\nYear: 1998\n\nAbstract: In mobile computing systems the network configuration changes due to node mobility. This paper identifies the issues a group communication service has to take into account in order to handle node mobility. These include the need to identify the location of a node, and the ability to cope with inaccuracies in the determination of a group membership. A multi-level architecture for group communication in mobile systems is presented. This architecture contains a synchronous proximity layer protocol to determine the set of mobile nodes in the proximity of a given node in the network. This information is used by a three-round group membership protocol for construction of groups used by mobile applications. As an example, the architecture is specialized to solve the channel allocation problem.","Title: Link scheduling in wireless sensor networks: Distributed edge-coloring revisited\nYear: 2008\n\nAbstract: We consider the problem of link scheduling in a sensor network employing a TDMA MAC protocol. Our algorithm consists of two phases. The first phase involves edge-coloring : an assignment of a color to each edge in the network such that no two edges incident on the same node are assigned the same color. Our main result for the first phase is a distributed edge-coloring algorithm that needs at most ( Δ + 1 ) colors, where Δ is the maximum degree of the network. To our knowledge, this is the first distributed algorithm that can edge-color a graph using at most ( Δ + 1 ) colors. The second phase uses the edge-coloring solution for link scheduling . We map each color to a unique timeslot and attempt to assign a direction of transmission along each edge such that the hidden terminal problem is avoided; an important result we obtain is a characterization of network topologies for which such an assignment exists. Next, we consider topologies for which a feasible transmission assignment does not exist for all edges, and obtain such an assignment using additional timeslots. Finally, we show that reversing the direction of transmission along every edge leads to another feasible direction of transmission. Using both the transmission assignments, we obtain a TDMA MAC schedule which enables two-way communication between every pair of adjacent sensor nodes. For acyclic topologies, we prove that at most 2 ( Δ + 1 ) timeslots are required. Results for general topologies are demonstrated using simulations; for sparse graphs, we show that the number of timeslots required is around 2 ( Δ + 1 ) . We show that the message and time complexity of our algorithm is O ( n Δ 2 + n 2 m ) , where n is the number of nodes and m is the number of edges in the network. Through simulations, we demonstrate that the energy consumption of our solution increases linearly with Δ . We also propose extensions to account for non-ideal radio characteristics.","Title: Csma-Based Mac Protocol For Cognitive Radio Networks\nYear: 2007\n\nAbstract: Cognitive radios (CR) technology enables wireless devices to dynamically switch between channels in a wide range of frequency bands and utilize unused parts of licensed and unlicensed frequency bands. The CR-enabled devices can either form a stand-alone multi-hop wireless network or form a multi-hop wireless backbone network that can connect different types of devices together. In a multi-hop wireless network composed of CR-enabled devices the number and the set of available channels vary from one node to another. This is in contrast to the existing multi-hop wireless mesh networks where all the nodes have the same set of channels available. In this paper we present a CSMA-based MAC protocol for CR-based multihop network. This protocol is based on the channel segregation technique proposed for cellular networks. Simulation results indicate that the protocol incurs low latency and achieves reasonable throughput.","Title: Dependency sequences and hierarchical clocks: efficient alternatives to vector clocks for mobile computing systems\nYear: 1997\n\nAbstract: Vector clocks have been used to capture causal dependencies between processes in distributed computing systems. Vector clocks are not suitable for mobile computing systems due to (i) lack of scalability: its size is equal to the number of nodes, and (ii) its inability to cope with fluctuations in the number of nodes. This paper presents two efficient alternatives to vector clock, namely, sets of dependency sequences, and hierarchical clock. Both the alternatives are scalable and are immune to fluctuations in the number of nodes in the system.","Title: Reliable multicast in mobile networks\nYear: 2003\n\nAbstract: This paper describes a distributed algorithm for reliable multicast in mobile cellular networks. In the proposed solution the multicast message is flooded to all the base stations over reliable channels. The base stations then collectively ensure that all mobile nodes belonging to the multicast group get the message. The originality of our solution is that it is fully decentralized. Each base station can independently decide when to flush a message from its buffer. Even if a node moves from one cell to another while a multicast is in progress, delivery of the message to the node is guaranteed. Simulation experiments show that using the proposed solution, memory requirements at the base stations are significantly smaller than by using centralized solutions.","Title: Time-Efficient Layer-2 Auto-Configuration for Cognitive Radios\nYear: 2005\n\nAbstract: timeslots, where is the maximum number of nodes deployed, is the maximum number of available channels for communication and is the diameter of the network. Assuming all nodes are aware of and , we present both diameter-aware and diameter-unaware versions of the algorithm. For highly sparse networks like linear chain topology where , with and , the diameter- aware conguration protocol terminates within and the diameter-unaware version terminates within .","Title: ATR-MAC: deadline driven data collection from smartmeters in absence of aggregation\nYear: 2013\n\nAbstract: Deployment of Smart Grid networks throughout cities introduces a realistic scenario for a large scale sensor network. Smart Meters create a wireless mesh network for receiving commands and sending metering reports back to provider company. The challenges of reliable and timely communication call for a fresh review of the well studied topic of Wireless Sensor Networks (WSN). We provide a centralized MAC solution for data collection, ATR-MAC, that relaxes requirements in general purpose WSNs, but emphasizes on difficulties a Smart Metering deployment will face. ATR-MAC considers variable reuse distances for minimizing propagation delay. It also increases efficiency of collection deadline instead of energy efficiency, a common concern of general-purpose WSN MAC protocols. We provide time and buffer size analysis of our algorithm, prove its correctness and show experimental results using implementation on a testbed.","Title: Time-efficient distributed layer-2 auto-configuration for cognitive radio networks\nYear: 2008\n\nAbstract: Cognitive radios (CR) have the ability to dynamically adapt to local spectrum availability. In a network comprised of CR-enabled devices, layer-2 auto-configuration involves determining a common set of channels to facilitate communication among participating nodes. This is a unique challenge as nodes in the CR network may be unaware of (a) their neighbors and (b) the channels on which they can communicate with a neighbor. In this paper, we propose a time-efficient distributed algorithm for layer-2 auto-configuration for a CR network. Our algorithm finds the globally common channel set in 2MN+O(DN) timeslots, where each node is assigned a unique identifier from the range [1,...,N], M is the maximum number of channels available for communication, and D is the diameter of the network. All nodes know M and N. We present both diameter-aware and diameter-unaware versions of the algorithm. We then show that the proposed algorithms are efficient by proving a matching lower bound. Finally, we investigate a special case when nodes have more knowledge available at their disposal and discuss how the time-complexity of our algorithm can be improved under this case.","Title: Max-Min D-Cluster Formation in Wireless Ad Hoc Networks\nYear: 2000\n\nAbstract: An ad hoc network may be logically represented as a set of clusters. The clusterheads form a -hop dominating set. Each node is at most hops from a clusterhead. Clusterheads form a virtual backbone and may be used to route packets for nodes in their cluster. Previous heuristics restricted themselves to -hop clusters. We show that the minimum -hop dominating set problem is NP-complete. Then we present a heuristic to form -clusters in a wireless ad hoc network. Nodes are assumed to have non-deterministic mobility pattern. Clusters are formed by diffusing node identities along the wireless links. When the heuristic terminates, a node either becomes a clusterhead, or is at most wireless hops away from its clusterhead. The value of is a parameter of the heuristic. The heuristic can be run either at regular intervals, or whenever the network configura- tion changes. One of the features of the heuristic is that it t ends to re-elect existing clusterheads even when the network configuration c hanges. This helps to reduce the communication overheads during transition from old clusterheads to new clusterheads. Also, there is a tendency to evenly dis- tribute the mobile nodes among the clusterheads, and evently distribute the responsibility of acting as clusterheads among all nodes. Thus, the heuristic is fair and stable. Simulation experiments demonstrate that the proposed heuristic is better than the two earlier heuristics, namely the LCA (1) and Degree based (11) solutions.","Title: Emulation of multipath effects on a wireless testbed and its impact on MAC layer performance\nYear: 2012\n\nAbstract: Field experiments are an important part of research in wireless networks. Since the wireless channel varies with location and time, the results vary for the same field experiment at a different place and time. Assumptions about the wireless environment can lead to biased results. It is necessary to shield wireless transmission from uncontrolled interference in order to make the experiment repeatable. This paper describes $$\\underline{A}$$ dvanced wirele $$\\underline{SS}$$ $$\\underline{E}$$ nvironment $$\\underline{R}$$ esearch $$\\underline{T}$$ estbed (ASSERT) which uses shielded co-axial cables as the communication media for radio signals to conduct reliable, scalable and accurate wireless experiments. Shielding the transmission also protects the signal from random burst of noise introduced by the environment. The paper describes how the combination of programmable attenuators and RF splitters/combiners, which are part of ASSERT, helps in emulating complex and varying environments including those in which multipath interference plays a significant role. Our experimental results indicate that (1) tweaking the MAC layer and retransmissions at the application layer neutralize, to an extent, the impact of multipath effects when the received signal strength is extremely good, and (2) when the received signal strength falls below a certain threshold multipath interference plays a significant role.","Title: Optimal control problem for the time-dependent Kirchhoff-Love plate in a domain with rough boundary.\nYear: 2013\n\nAbstract: In this paper, we study the asymptotic behavior of an optimal control problem for the time-dependent Kirchhoff-Love plate whose middle surface has a very rough boundary. We identify the limit problem which is an optimal control problem for the limit equation with a different cost functional.","Title: The impact of mobility on the time complexity for deterministic broadcasting in radio networks\nYear: 2011\n\nAbstract: We study the time complexity for deterministic broadcasting algorithms in mobile radio networks. The broadcast operation consists of a source node successfully communicating its message to every other node. In multi-hop radio networks such as MANETs, the message may traverse multiple other nodes. Nodes have no prior knowledge besides the number n of nodes in the network and its diameter D. The problem we address has been extensively studied for static networks. Our work quantifies the impact of mobility. We consider three families of graphs: undirected graphs of constant contention degree, undirected graphs of non-constant contention degree and directed graphs of non-constant contention degree. We prove the lower bounds of Ω(n log n) time slots for the first family, Ω(n²/D² log D + D) time slots for the second and Ω(n²/D² log D + n log D) for the third. At the time of writing, the corresponding tightest lower bounds derived in the static case are, respectively, Ω(D log n), Ω(n log/log n / D) and Ω(n log D).","Title: Dynamic coexistence of frequency hopping networks using parallel and Gaussian allocations\nYear: 2009\n\nAbstract: This paper studies the coexistence of several independent and dynamic wireless networks using the frequency hopping technique in the unlicensed radio band. We propose a new hopping scheme that allows more networks to collocate effectively, but does not violate federal restrictions regarding frequency constraint (related to the minimum number of frequencies in a hopping set) and time constraint (related to the maximum duration of using a particular frequency). The coexisting networks follow the Gaussian distribution in choosing transmission frequencies from parallel hopping spaces without the overhead of extra message exchange. Simulation results include comparison with other contemporary approaches and establish the viability of the proposed scheme.","Title: On the relative speed of messages and hierarchical channels\nYear: 1992\n\nAbstract: The authors study the concept of relative speed of messages and a hierarchy of such speeds which results in a hierarchical channel. They present examples of applications where hierarchical channels are useful and an implementation of such a channel using selective flooding. They describe a mechanism that permits a programmer to specify a partial order among channels, and compare the hierarchical channels with F-channels.","Title: A routing algorithm for wireless ad hoc networks with unidirectional links\nYear: 2001\n\nAbstract: Most of the routing algorithms for ad hoc networks assume that all wireless links are bidirectional. In reality, some links may be unidirectional. In this paper we show that the presence of such links can jeopardize the performance of the existing distance vector routing algorithms. We also present modifications to distance vector based routing algorithms to make them work in ad hoc networks with unidirectional links. For a network of n nodes, neighbors exchange n x n matrices to propagate routing information. This results in loop-free routes.","Title: A QoS-aware MAC layer protocol for wireless LANs\nYear: 2004\n\nAbstract: With advances in physical layer technologies, WLANs are now connected with wired networks and act as parts of the entire networks. Since demands for QoS sensitive applications are extremely high, WLANs, as parts of heterogeneous networks, are required to be QoS-aware. In this paper we present a new QoS-aware multi-access scheme, called ADCF, designed to assure weighted fair queuing in a purely distributed way and to achieve admission control per frame. The results of simulations show that ADCF yields stable weighted fair queuing with consistent performance under most conditions. In most cases, ADCF outperforms DCF of IEEE 802.11 and EDCF of IEEE 802.11e. Also, ADCF guarantees starvation free channel access for a low priority flow.","Title: Enhancing ASSERT: making an accurate testbed friendly\nYear: 2011\n\nAbstract: This article discusses lessons learned from use of our publicly available wireless networking testbed, assert[1]. In [1] we discussed the design and implementation phase of a testbed based on a set of propositions. By opening the testbed to users not familiar with underlying architecture of assert, we put these propositions to the test. While fidelity of the testbed is a major challenge for developers, users assume the fidelity as a given and look for ease of use comparable with a simulator. We list the main demands by users of our testbed and the way we addressed these demands during an enhancement phase.","Title: Overload-state downlink resource allocation in LTE MAC layer\nYear: 2013\n\nAbstract: This paper presents a quality of service-aware resource scheduling algorithm targeted for downlink traffic in the UMTS Long-Term Evolution Medium Access Control layer with emphasis for support in an overload state. Specifically, multiple real-time traffic metrics including latency, loss, and queue depth are normalized and processed via an array of ranking functions and multiplexed into an aggregate rank. This aggregate rank is then used in a fractional knapsack scheduling implementation. Experiments with this scheduling mechanism show improved traffic processing intelligence over existing scheduling models, especially in overload states.","Title: Causality and the Spatial-Temporal Ordering of Events in Mobile Systems\nYear: 1999\n\nAbstract: Several mobile computing applications require that both the order of occurrence of events, and the location of their occurrence, be taken into account during decision making. Thus, processes need to track the location of nodes and synchronize their clocks. In this paper we present a framework, based on the capabilities of Global Positioning System, which provides processes with a global virtual clock and a positioning service. We introduce then the notion of space-time vector used by processes to track the mobility of nodes.","Title: Fault Tolerant Mobility Planning for Rapidly Deployable Wireless Networks\nYear: 1998\n\nAbstract: Rapidly deployable wireless networks consist of mobile base stations and less powerful mobile hosts. The mobile base stations have to maintain wireless connectivity while on the move along pre-defined paths. Physical obstructions and wireless range limitations may prevent a pair of mobile base stations from establishing a wireless link. We study situations of distance-constrained mobility, and fault situations like distance and topology induced mobility deadlocks. We also propose a deadlock avoidance mobility scheme using repeaters, and derive an upper bound on the number of repeaters. We propose two heuristics, using sleeper nodes, for providing coverage to areas that may lose coverage due to a mobile base station crash.","Title: Wireless Data Center with Millimeter Wave Network\nYear: 2010\n\nAbstract: Data centers are becoming increasingly popular for a wide variety of applications such as search, gaming, email and so on. The complex wiring issues in data centers have motivated us to consider a wireless solution for data centers which meets the design goals of a typical data center network while providing the additional benefit of flexibility in the network. The wireless data center is based on the recently released IEEE 802.15.3c wireless networking standard in the 60 GHz ISM band. The standard supports multi-Gbps data rates and enables the transceivers to set up point-to-point links with each other, which makes it suitable for data center interconnects. In this paper, we use 60 GHz wireless technology to design a wireless data center and show how various data center interconnects such as 3-tier and fat-tree can be emulated on such a wireless network.","Title: Aggressive Error Recovery for TCP over wireless links\nYear: 2000\n\nAbstract: TCP's congestion control handless packet loss due to congestion in the network. Over wireless links, packet loss may also be due to signal fading. Wireless LAN traffic under High Bit Error rate (BER) suffers great throughput degradation due to the current congestion control mechanism. Our algorithm allows TCP to send as much data as possible within a threshold that optimizes throughput while recovering from a high BER on a wireless LAN link. We will refer to the error recovery mechanism as Aggressive Error Recovery (AER) and call the new TCP version as TCP Noor.","Title: Exploring Alternatives to Channel Change for Improving the Coexistence of IEEE 802.15.4 and IEEE 802.11\nYear: 2012\n\nAbstract: The recent increase in the number of technologies operating in the 2.4GHz ISM band has drawn attention towards the impact they can have on each other. In this paper, we have conducted a case study about coexistence of IEEE 802.11and IEEE 802.15.4 which has led us to discover previously unknown interactions. We have performed experiments using real hardware to evaluate the impact of IEEE 802.11 on IEEE 802.15.4 and vice versa. More importantly, we have identified IEEE 802.11MAC/PHY layer parameters that could be changed in order to improve the performance of coexisting IEEE 802.15.4 nodes. We have also identified the order in which these adjustments should be made.","Title: Reliable Broadcast in Wireless Mobile Ad Hoc Networks\nYear: 2006\n\nAbstract: We propose a single source reliable broadcasting algorithm for linear grid-based networks where a message is guaranteed to be delivered to all the nodes of the network. The nodes are mobile and can move from one grid point to another. The solution does not require the nodes to know the network size or its diameter. The only information a node has is its identity and its position. On average, only a subset of nodes transmit and they transmit only once to achieve reliable broadcast. The protocol is contention-free and energy-efficient. We show that reliable broadcast can be achieved in O(Dlog n) time-slots despite node mobility, where D is the diameter of the network and n the number of nodes.","Title: Load-balanced location management for cellular mobile systems using quorums and dynamic hashing\nYear: 2001\n\nAbstract: This paper presents a new distributed location management strategy for cellular mobile systems. Its salient features are fast location update and query, load balancing among location servers, and scalability. The strategy employs dynamic hashing techniques and quorums to manage location update and query operations. The proposed strategy does not require a home location register (HLR) to be associated with each mobile node. Location updates and queries for a mobile node are multicast to subsets of location servers, which change with time depending on the location of mobile node/querying node and load on the servers. Simulation experiments demonstrate that such dynamism prevents situations of heavy load on some location servers when mobile nodes are not uniformly distributed in space, or when some mobile nodes have their location updated or queried more often than others. Also, queries return the latest location information of a mobile node with a very high probability. The proposed scheme requires at most one unicast and two rounds of message multicasting for location update and query operations. All multicast messages have a small payload and are restricted to the high bandwidth wired part of the mobile network resulting in low communication overhead. Moreover, if a quorum of location servers gets overloaded, part of its load can be transferred to another lightly loaded quorum using dynamic hashing techniques.","Title: Droplet microfluidics for chip-based diagnostics.\nYear: 2014\n\nAbstract: Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays.","Title: Multiplex, Quantitative, Reverse Transcription PCR Detection of Influenza Viruses Using Droplet Microfluidic Technology.\nYear: 2015\n\nAbstract: Quantitative, reverse transcription, polymerase chain reaction (qRT-PCR) is facilitated by leveraging droplet microfluidic (DMF) system, which due to its precision dispensing and sample handling capabilities at microliter and lower volumes has emerged as a popular method for miniaturization of the PCR platform. This work substantially improves and extends the functional capabilities of our previously demonstrated single qRT-PCR micro-chip, which utilized a combination of electrostatic and electrowetting droplet actuation. In the reported work we illustrate a spatially multiplexed micro-device that is capable of conducting up to eight parallel, real-time PCR reactions per usage, with adjustable control on the PCR thermal cycling parameters (both process time and temperature set-points). This micro-device has been utilized to detect and quantify the presence of two clinically relevant respiratory viruses, Influenza A and Influenza B, in human samples (nasopharyngeal swabs, throat swabs). The device performed accurate detection and quantification of the two respiratory viruses, over several orders of RNA copy counts, in unknown (blind) panels of extracted patient samples with acceptably high PCR efficiency (>94%). The multi-stage qRT-PCR assays on eight panel patient samples were accomplished within 35-40 min, with a detection limit for the target Influenza virus RNAs estimated to be less than 10 RNA copies per reaction.","Title: CHAMELEON: A Framework for Coexistence of Wireless Technologies in an Unlicensed Band\nYear: 2014\n\nAbstract: The recent increase in the number of technologies operating in the 2.4 GHz ISM band has drawn attention towards the impact they can have on each other. In this paper, we have conducted a case study about coexistence of IEEE 802.11 and IEEE 802.15.4 which has led us to discover previously unknown interactions. We show through extensive experiments that CCA method used by a wireless device can significantly change the coexistence scenario. We also highlight the ways in which coexistence can be improved by making runtime adjustments to some MAC/PHY layer parameters and show their effectiveness. Furthermore, we propose a framework which exploits the pervasiveness and ubiquity of Wi-Fi to improve coexistence among wireless technologies in the 2.4 GHz ISM band. Our framework has the capability to detect the presence of wireless technologies operating anywhere in the 2.4 GHz ISM band and also accounts for devices whose signatures do not exist in the database. It facilitates the Wi-Fi AP to make decisions such as changing the channel or making MAC/PHY layer adjustments which are compliant with the configured coexistence policy thus improving the performance of the wireless devices. We have implemented our framework on real hardware and evaluated its performance in the presence of ZigBee.","Title: Proactive resource allocation optimization in LTE with inter-cell interference coordination\nYear: 2014\n\nAbstract: This paper presents a distributed, dynamic self-organizing network (SON) solution for downlink resources in an LTE network, triggered by support vector regression instances predicting various traffic loads on the nodes in the network. The proposed SON algorithm pro-actively allocates resources to nodes which are expected to experience traffic spikes before the higher traffic load occurs, as opposed to overloaded nodes reacting to a resource-exhaustion condition. In addition, the solution ensures inter-cell interference coordination is maintained across the LTE cells/sectors.","Title: Asymptotic behavior of the solutions of a degenerating elliptic equation in a thin multidomain.\nYear: 2014\n\nAbstract: We study the behavior of the solutions u(epsilon) of a degenerating elliptic equation in the framework of the dimension reduction problem coupled with an oscillating boundary. Under a suitable choice of the scalings on the source term and on the diffusivity coefficients, we prove that the limit problem is a nonlocal problem involving only the diffusion through the upper part of the domain.","Title: Maximal global snapshot with concurrent initiators\nYear: 1994\n\nAbstract: In a distributed system multiple nodes may initiate snapshot collection concurrently. In this paper we present a global snapshot collection algorithm that combines the information collected by each initiator. This generates a maximal, consistent global snapshot that is more recent than the snapshot collected by any initiator. Global snapshots are used to establish checkpoints for recovery from node failures. A maximal snapshot implies that the amount of computation lost during roll-back after node failures, is minimized. We also present an efficient information dissemination strategy that nodes can employ to exchange snapshot information with each other.","Title: Towards 60ghz Wireless Switching Interconnect\nYear: 2013\n\nAbstract: In the era of cloud computing and high performance computing clusters, interconnection networks are in high demand and have many applications including data center networks. Typically, nodes of interconnects are placed in a closed room and are connected using a set of wires through one or more high-end switches with little or no reconfigurability to the interconnect. In this paper, we present a design of wireless switching interconnects using 60GHz technology. The Gigabit, point-to-point and extremely directional links in the 60GHz band are used to replace wired connections in such a network to provide flexibility and reconfigurability. We extend our previous investigation where a high level node placement technique was discussed to arrange nodes into a closed polygon. Here we present an initial design for exact arrangement and placement of the fat-tree nodes, suitable for small to medium size wireless switching interconnects. We argue that creating a completely wireless interconnect is viable, and present mathematical equations and a proof to support the claim.","Title: Concurrency in polygonally arranged wireless Data Centers with all line-of-sight links\nYear: 2014\n\nAbstract: The use of wireless links can provide flexibility and reconfigurability to data center networks. Recent investigations show that 60GHz millimeter-wave technology can be used in wireless data center networks. The steerable millimeter-wave transceiver works as a multi-port switch where point-to-point links are established using beam-forming. Considering an interference model, specific to the wireless data center, we propose a new algorithm for k-pod fat-tree data center topology mapping. Further, we propose to group all links of the network into sets of mutually concurrent links. By assigning a time slot for all concurrent links in a set, we devise a TDMA scheduling algorithm for the wireless network. We show that the concurrent wireless transmissions could result in O(k2) number of slots that is k times better than graph based coloring approach. By increasing the concurrency, we argue that the use of 60GHz technology is more viable in building completely wireless data centers.","Title: Improving the performance of multipath TCP over heterogeneous paths using slow path adaptation\nYear: 2014\n\nAbstract: Multipath TCP (MPTCP) is an extension of TCP, developed by Internet Engineering Task Force (IETF) to support communication between source and destination through multiple flows under a single connection session. We have conducted several experiments with real hardware on flows with extreme variation in path quality and found that unless receive buffer size is increased to a much higher value, the overall throughput decreases below the level of single-path TCP throughput. We propose a Slow Path Adaptation (SPA) technique to overcome this issue without affecting other performance parameters. The implementation is done on Linux kernel and experimental results are presented.","Title: MANETconf: configuration of hosts in a mobile ad hoc network\nYear: 2002\n\nAbstract: A mobile ad hoc network (MANET) is a multi-hop wireless network capable of autonomous operation. The mobility of MANET nodes can lead to frequent and unpredictable topology changes. Most MANET literature assumes that network related information of a node (such as its IP address, netmask, etc.) is configured statically, prior to the node joining the MANET. However, not all nodes have IP addresses permanently assigned to them. Such nodes rely on a centralized server and use a dynamic host configuration protocol, like DHCP (dynamic host configuration protocol), to acquire an IP address. Such a solution cannot be employed in MANETs due to the unavailability of any centralized DHCP server. In this paper, we first present a survey of possible solutions approaches, and discuss their limitations. Then, we present a distributed dynamic host configuration protocol designed to configure nodes in a MANET. We show that the proposed protocol works correctly and does not have the limitations of earlier approaches. Finally, we evaluate the performance of the solution through simulation experiments, and conclude with a discussion of related security issues.","Title: Energy efficient schemes for wireless sensor networks with multiple mobile base stations\nYear: 2003\n\nAbstract: One of the main design issues for a sensor network is conservation of the energy available at each sensor node. We propose to deploy multiple, mobile base stations to prolong the lifetime of the sensor network. We split the lifetime of the sensor network into equal periods of time known as rounds. Base stations are relocated at the start of a round. Our method uses an integer linear program to determine new locations for the base stations and a flow-based routing protocol to ensure energy efficient routing during each round. We propose four metrics and evaluate our solution using these metrics. Based on the simulation results we show that employing multiple, mobile base stations in accordance with the solution given by our schemes would significantly increase the lifetime of the sensor network.","Title: Service differentiation mechanisms for IEEE 802.11-based wireless networks\nYear: 2004\n\nAbstract: In this paper, we study two medium access control (MAC) sublayer policies, namely, Schedule After Backoff (SAB) and Schedule Before Backoff (SBB), which offer differentiated services in IEEE 802.11-based wireless networks. Both policies control channel access based on frame priorities. In the SAB policy, each node maintains concurrent backoff instances (one per priority class) with different parameter values to realize service differentiation. High-priority data frames use a shorter contention window, so that, in most cases, they are transmitted before the low-priority ones. The Enhanced Distributed Coordination Function (EDCF) scheme specified in the upcoming IEEE 802.11e standard is based on the SAB policy. Recent studies (7) have shown that under high loads of high-priority traffic, EDCF starves low-priority frames. We propose SBB policy, which provides service differentiation without the need for maintaining concurrent backoff instances. In SBB, frame transmission proceeds in two sequential steps: (i) selecting the next frame to be transmitted, and (ii) channel access functionality until the selected frame is either successfully transmitted or its number of retransmissions exceeds the retry limit. These two steps are independent and can be performed using several alternatives. Depending on the way the two steps are carried out, we present four SBB-based MAC schemes. We evaluate SAB and SBB-based MAC schemes through simulation experiments. Our simulation results show that the SBB policy does not starve low- priority traffic and offers differentiated service on par with SAB. This suggests that maintenance of concurrent backoff instances contributes little towards performance improvement. Keywords—ad hoc, DCF, IEEE 802.11e, QoS, WLANs.","Title: Modifications to TCP for improved performance and reliable end-to-end communication in wireless networks\nYear: 1999\n\nAbstract: Wireless ad-hoc networks consist of a set of identical mobile nodes that communicate with each other over limited range wireless links. These wireless links are lossy due to noise and co-channel interference. Moreover, node mobility can lead to establishment of new links and disappearance of some existing links. Current implementations of TCP are not suitably equipped to operate in ad-hoc networks. Loss of packets due to path disruption can be misinterpreted as congestion. We propose to introduce modifications to TCP such that it can work for these kind of dynamic networks. These modifications will exploit the mobility support in the underlying routing protocol. The information provided by the routing protocol can be used to send explicit freeze and resume signals to the TCP source on link disruption and restoration. The proposed solutions can inter-operate with existing TCP implementations, have low communication overheads and are consistent with various ad-hoc network routing protocols","Title: A tunneling approach to routing with unidirectional links in mobile ad-hoc networks\nYear: 2000\n\nAbstract: Mobile ad hoc networks (MANETs) consist of a set of similar mobile nodes, communicating with each other using wireless links. As a node may not be able to directly reach every other node, a packet may need to traverse multiple wireless links from its source to its destination. Unidirectional links can occur in such networks. Several existing routing protocols implicitly assume bidirectional links when making their routing decisions. Not using unidirectional links can lead to sub-optimal routes. A tunneling solution to allow efficient operation in ad hoc networks with unidirectional links is presented. The tunneling solution uses information gathered by the routing protocol to tunnel packets from the end-point of the unidirectional link to its source. A naive implementation of tunneling could lead to loops in the system and a deluge of packets. This is because when ACKs (acknowledgments) for link layer messages are tunneled across unidirectional links, ACKs for them may end up being generated recursively. The solution presented here prevents such a packet explosion from occurring","Title: Extending Paxos/LastVoting with an Adequate Communication Layer for Wireless Ad Hoc Networks\nYear: 2008\n\nAbstract: Most papers addressing consensus in wireless ad hoc networks adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad hoc networks. The recently proposed HO model does not have this drawback. The paper shows that an existing algorithm and the HO model can be used for multi-hop wireless ad hoc networks, if extended with an adequate communication layer. The description of the communication layer is augmented with simulation results that validate the feasibility of our approach and provide better understanding of the behavior of wireless environments.","Title: Gradient-Based Aggregation in Forest of Sensors (GrAFS)\nYear: 2011\n\nAbstract: In several sensing applications the parameter being sensed exhibits a high spatial correlation. For example, if the temperature of a region is being monitored, there are distinct hot and cold spots. The area close to the hot spots is usually warmer than average, with a temperature gradient between the hot and cold spots. We exploit this correlation of sensor data to form a forest of logical trees, with the trees collectively spanning all the sensor nodes. The root of a tree corresponds to a sensor reporting the local peak value. The tree nodes represent the value gradient: each node's sensed value is smaller than that of its parent, and greater than that of its children. GrAFS provides a mechanism to maintain some information at the local peaks and the sink. Using this information the sink can answer several queries either directly, or by probing the region of the sensor field that holds the answer. Thus, queries can be answered in a time and/or bandwidth efficient manner. The GrAFS approach to data aggregation can easily adapt to changes in the spatial distribution of sensed values, and also cope with message losses and sensor node failures. Implementation on MICA2 motes and simulation experiments conducted using TinyOS quantify the performance of GrAFS.","Title: Causality and the Spatial–Temporal Ordering in Mobile Systems\nYear: 2004\n\nAbstract: Several mobile computing applications require that both the order and location of occurrence of events be taken into account during decision making. Thus, processes need to track the location of nodes and synchronize their clocks. The Global Positioning System can be employed to mimic a global virtual clock that keeps the local clocks of participating nodes in synchrony with each other. The global virtual clock in conjunction with a space–time vector can track the mobility of nodes. Nodes can prioritize resource requests on the basis of request time as well as the requester's distance from the resource. Two distributed mutual exclusion algorithms that employ the space–time vector are presented. The error in the estimates of a mobile node, due to clock drift, about the region in which other mobile nodes may be present is formulated. Various resource allocation policies can react differently to such errors leading to performance differences. However, every policy should ensure that resource allocation has the properties of safety, deadlock freedom, liveness, and fairness.","Title: Periodic Controls in an Oscillating Domain: Controls via Unfolding and Homogenization.\nYear: 2015\n\nAbstract: An optimal control problem in a two-dimensional domain with a rapidly oscillating boundary is considered. The main features of this article are on two points, namely, we consider periodic controls in the thin periodic slabs of period epsilon > 0, a small parameter, and height O(1) in the oscillatory part, and the controls are characterized using unfolding operators. We then do a homogenization analysis of the optimal control problems as epsilon -> 0 with L-2 as well as Dirichlet (gradient-type) cost functionals.","Title: On the Fidelity of Single-Machine Network Emulation in Linux\nYear: 2015\n\nAbstract: Network emulation strikes the balance between using real machines on full-fledged networks and running software models of applications and networks in simulation environments. Advanced Linux features make it possible to emulate entire networks on a single machine, enabling experiments that are much easier to run and repeat. However, some of these features were not designed with the primary purpose of supporting emulation frameworks: if not carefully configured, they can lead to erroneous results. In this paper we note a few properties of Linux-based network emulation that researchers should consider while planning their experiments. We also recommend a particular configuration that improves the fidelity of emulation results.","Title: Normalization of Application Performance in IEEE 802.11 Networks.\nYear: 2016\n\nAbstract: The IEEE 802.11 standards define a distributed scheme for Wi-Fi access points and stations to fairly share the wireless medium. Even if fully standard-compliant, Wi-Fi devices from different vendors have implementation differences that lead to disparities in their ability to access the medium. Erratic upper-layer behaviors become manifest when devices that exhibit such disparities inter-operate within one network. In this paper we show examples of those behaviors based on common use cases. We find that a primary cause of performance inconsistency for most network applications is the uneven ability of different IEEE 802.11 devices to access the shared medium for transmission of TCP acknowledgments, further aggravated by the excessive size of the buffers where those packets are queued before transmission. We devise and validate in a real network an effective solution for Linux hosts that is based on the link-layer priorities of IEEE 802.11e. This solution allows researchers conducting Wi-Fi experiments to collect device-independent results, and application providers to guarantee a consistent experience to their users across different devices.","Title: A variant of environmental adaptation method with real parameter encoding and its application in economic load dispatch problem.\nYear: 2017\n\nAbstract: Environmental Adaptation Method (EAM) and Improved Environmental Adaptation Method (IEAM) were proposed to solve optimization problems with the biological theory of adaptation in mind. Both of these algorithms work with binary encoding, and their performance is comparable with other state-of-art algorithms. To further improve the performance of these algorithms, some major changes are incorporated into the proposed algorithm. The proposed algorithm works with the real value parameter encoding, and, in order to maintain significant convergence rate and diversity, it maintains a balance between exploitation and exploration. The choice to explore or exploit a solution depends on the fitness of the individual. The performance of the proposed algorithm is compared with 17 state-of-art algorithms in 2-D, 3-D, 5-D, 10-D and 20-D dimensions using the COCO (COmparing Continuous Optimisers) framework with Black-Box Optimization Benchmarking (BBOB) functions. It outperforms all other algorithms in 3-D and 5-D, and its performance is comparable to other algorithms for other dimensions. In addition, IEAM-R has been applied to the real world problem of economic load dispatch, and its results demonstrate that it gives minimum fuel cost when compared to other algorithms in different cases.","Title: Adaptive 360-Degree Video Streaming using Scalable Video Coding.\nYear: 2017\n\nAbstract: Virtual reality and 360-degree video streaming are growing rapidly, yet, streaming high-quality 360-degree video is still challenging due to high bandwidth requirements. Existing solutions reduce bandwidth consumption by streaming high-quality video only for the user's viewport. However, adding the spatial domain (viewport) to the video adaptation space prevents the existing solutions from buffering future video chunks for a duration longer than the interval that user's viewport is predictable. This makes playback more prone to video freezes due to rebuffering, which severely degrades the user's Quality of Experience especially under challenging network conditions. We propose a new method that alleviates the restrictions on buffer duration by utilizing scalable video coding. Our method significantly reduces the occurrence of rebuffering on links with varying bandwidth without compromising playback quality or bandwidth efficiency compared to the existing solutions. We demonstrate the efficiency of our proposed method using experimental results with real world cellular network bandwidth traces.","Title: Layer-Assisted Adaptive Video Streaming.\nYear: 2018\n\nAbstract: HTTP Adaptive Streaming (HAS) is the widely adopted solution for video streaming over the Internet. When network throughput is highly variable, designing an optimal HAS solution that maximizes Quality of Experience (QoE) becomes challenging. Each chunk should be prefetched at highest possible quality while rebufferings and quality switches are minimized. Scalable Video Coding (SVC), with its layered encoding of video, provides more flexibility for HAS clients. It can reduce the occurrence of rebufferings under variable network conditions. However, SVC introduces at least 10% overhead on video bitrate per layer and increases the number of HTTP requests to fetch video chunks. So streaming SVC video at high qualities is more expensive. We propose a solutions that employs both SVC and non-SVC video to improve user's QoE while avoiding the increased bandwidth overhead and HTTP signaling of SVC. Our experiments using real-world bandwidth traces show that this method improves QoE compared to the state-of-the-art adaptation methods under various network conditions.","Title: Topological asymptotic analysis of an optimal control problem modeled by a coupled system.\nYear: 2018\n\nAbstract: In this paper, we deal with the topological asymptotic analysis of an optimal control problem modeled by a coupled system. The control is a geometrical object and the cost is given by the misfit between a target function and the state, solution of the Helmholtz-Laplace coupled system. Higher-order topological derivatives are used to devise a non-iterative algorithm to compute the optimal control for the problem of interest. Numerical examples are presented in order to demonstrate the effectiveness of the proposed algorithm.","Title: FoV-Aware Edge Caching for Adaptive 360° Video Streaming.\nYear: 2018\n\nAbstract: In recent years, there has been growing popularity of Virtual Reality (VR), enabled by technologies like 360° video streaming. Streaming 360° video is extremely challenging due to high bandwidth and low latency requirements. Some VR solutions employ adaptive 360° video streaming which tries to reduce bandwidth consumption by only streaming high resolution video for user's Field of View (FoV). FoV is the part of the video which is being viewed by the user at any given time. Although FoV-adaptive 360° video streaming has been helpful in reducing bandwidth requirements, streaming 360° video from distant content servers is still challenging due to network latency. Caching popular content close to the end users not only decreases network latency, but also alleviates network bandwidth demands by reducing the number of future requests that have to be sent all the way to remote content servers. In this paper, we propose a novel caching policy based on users' FoV, called FoV-aware caching policy. In FoV-aware caching policy, we learn a probabilistic model of common-FoV for each 360° video based on previous users' viewing histories to improve caching performance. Through experiments with real users' head movement dataset, we show that our proposed approach improves cache hit ratio compared to Least Frequently Used (LFU) and Least Recently Used (LRU) caching policies by at least 40% and 17%, respectively.","Title: A Feedback Based Scheme for Improving TCP Performance in Ad-Hoc Wireless Networks\nYear: 2001\n\nAbstract: Ad-hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This frequent topology may lead to sudden packet losses and delays. Transport protocols like TCP have been built mainly for reliable, fixed networks. Hence, when used in ad-hoc networks, TCP misinterprets this loss as congestion and invokes congestion control. This leads to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed, so that the source can distinguish between route failure and network congestion. When a route is disrupted, the source is sent a Route Failure Notification(RFN) packet, allowing it to freeze its timers and stop sending packets. When the route is re-established, the source is informed through a Route Re-establishment Notification (RRN) packet, upon which it resumes by un-freezing timers and continuing packet transmissions. The simulated performance of TCP on ad-hoc networks with and without feedback is compared and reported. It is observed that in the event of route failures, as the route re-establishment time increases, the use of feedback provides significant gains in throughput as well as savings in unnecessary packet transmissions. Several further enhancements and directions for future work are also sketched.","Title: A General Analysis Framework for Soft Real-Time Tasks\nYear: 2019\n\nAbstract: Much recent work has been conducted on supporting soft real-time tasks on multiprocessors due to the multicore revolution. While most earlier works focus on the traditional sporadic task model with deterministic worst-case specification, several recent works investigate the stochastic nature of many workloads seen in practice, specifying task execution times using average-case provisioning instead...","Title: Dynamic Trajectory Generation and a Robust Controller to Intercept a Moving Ball in a Game Setting\nYear: 2020\n\nAbstract: Complex and interactive robot manipulation skills, such as playing a game of table tennis against a human opponent, are a novel problem with multifaceted challenges. Accurate dynamic trajectory generation in order to respond to the tennis ball from the opponent and a novel control scheme for robust and high-performance tracking of the ball in such dynamic situations is a prerequisite to winning th...","Title: End-To-End Real-Time Visual Perception Framework for Construction Automation.\nYear: 2021\n\nAbstract: In this work, we present a robotic solution to automate the task of wall construction. To that end, we present an end-to-end visual perception framework that can quickly detect and localize bricks in a clutter. Further, we present a light computational method of brick pose estimation that incorporates the above information. The proposed detection network predicts a rotated box compared to YOLO and SSD, thereby maximizing the object's region in the predicted box regions. In addition, precision P, recall R, and mean-average-precision (mAP) scores are reported to evaluate the proposed framework. We observed that for our task, the proposed scheme outperforms the upright bounding box detectors. Further, we deploy the proposed visual perception framework on a robotic system endowed with a UR5 robot manipulator and demonstrate that the system can successfully replicate a simplified version of the wall-building task in an autonomous mode.","Title: Improving 360-Degree Video Field-of-View Prediction and Edge Caching\nYear: 2021\n\nAbstract: Streaming 360° videos over the Internet to Head Mounted Displays (HMDs) requires high bandwidth owing to their high resolution. Viewers, limited by the Field of View (FoV) of the HMD, can only watch a small portion of the scene at a time. Therefore, predicting the future FoV of viewers and caching popular content in the mobile edge cloud can reduce both downloading latency and traffic over the cor...","Title: An approach using heuristic pheromones-based ACO modelling for green vehicle routing optimisation\nYear: 2022\n\nAbstract: A mathematical heuristic-based method was introduced for addressing the issue in green vehicle routing optimisation (GVRO). It analyses a large number of vehicles along with a limited refuelling network. A standard solution to this problem is given in this paper. GVRO seeks to minimise travel time renewable fuel sources while ensuring fewer emissions from greenhouse gases. An effective algorithm relies on a branch/slice optimisation algorithm that combines a variety of valid inequalities in exams to increase lower limits. Implementation of an optimisation algorithm based on heuristic ant colony optimisation (ACO) to obtain the best routes. In addition, the GVRO is better able to handle an accident and eliminates pollution by using the best alternatives.","Title: A System-on-Board Integrated Multi-analyte PoC Biosensor for Combined Analysis of Saliva and Exhaled Breath.\nYear: 2022\n\nAbstract: The need for oral health monitoring Point of Care (PoC) systems is ever growing. This is effectively highlighted by the ongoing COVID-19 pandemic where the lack of rapid PoC testing has placed an unsustainable burden on centralized laboratory testing. Urgent development has furthered pathogenic nucleic acid and antibody detection in oral samples throat swabs, but without corresponding advancements in biochemical monitoring through oral biosensing. We have recently reported two novel biosensor technologies for detection of high impact hormones: cortisol in saliva by organic electrolyte gated FETs (OEGFETs), and 8-isoprostane in exhaled breath condensate (EBC) using molecularly imprinted electroimpedance spectroscopy biosensors (MIP EIS). In this work, we report a first stage integration of the two biosensors - previously bench-top proven - with a miniaturized semi-hermetically sealed soft-fluidic enclosure, onto a low-power (<300 mW) customized printed circuit board. Our findings established comparable detection thresholds for the miniaturized board-based configuration and a lab-based test setup, and their ability to characterize, calibrate, and operate these small footprint biosensors. Testing with the 8-isoprostane EBC MIP EIS biosensors showed the system-on-board had an effective frequency range of 100-100kHz, comparable to lab bench impedance analyzers. Despite internal impedance increases of 210%, the expected data features are present in the impedance graphs collected with the PCB. The system-on-board experiments using OEGFET aptasensor showed a predictable behavior and comparable sensor detection range and resolution using unadulterated supernatant and serial dilutions of cortisol over a range of 273 μM to 2.73pM. The portable, multi-analyte oral biosensor is a promising prototype for future packaging and clinical validation.","Title: RDQS: A Geospatial Data Analysis System for Improving Roads Directionality Quality\nYear: 2022\n\nAbstract: With the increasing availability of smart devices, billions of users are currently relying on map services for many fundamental daily tasks such as obtaining directions and getting routes. It is becoming more and more important to verify the quality and consistency of route data presented by different map providers. However, verifying this consistency manually is a very time-consuming task. To address this problem, in this paper we introduce a novel geospatial data analysis system that is based on road directionality. We investigate our Road Directionality Quality System (RDQS) using multiple map providers, including: Bing Maps, Google Maps, and OpenStreetMap. Results from the experiments conducted show that our detection neural network is able to detect an arrow's position and direction in map images with >90% F1-Score across each of the different providers. We then utilize this model to analyze map images in six different regions. Our findings show that our approach can reliably assess map quality and discover discrepancies in road directionality across the different providers. We report the percentage of discrepancies found between map providers using this approach in a proposed study area. These results can help determine areas needs to be revised and prioritized to improve the overall quality of the data within maps.","Title: A Geospatial Method for Detecting Map-Based Road Segment Discrepancies\nYear: 2022\n\nAbstract: Today, people's lives are enriched by the integration of electronic maps via smartphones. Electronic maps are required for a variety of commercial activities, such as catering, movie viewing, and tourism. Route planning and navigation are particularly intrinsically linked to electronic maps. As a result, it is critical that the roads on the electronic map are complete and accurate. At the present time, there are discrepancies between the map roads of various providers. This paper evaluates the roads on various map providers' maps. Due to the varied terrain depicted on the map, assessing the road properties can be challenging. Additionally, roads of varying thicknesses exist within a tile image, making it difficult to quantify the map's road lengths. This paper proposes a method for extracting road segments using an image binarization technique and employs edge erosion to assist in automatically computing the length of roads within maps. Throughout the paper, we provide comparison and statistical analysis on using our proposed road length detection model across map providers. Results show that our detection model can identify road length accurately and hence provide an overall measure of quality of maps.","Title: Maps Vision: A Computer Vision-based System for Detecting Discrepancies in Map Textual Labels\nYear: 2022\n\nAbstract: We demonstrate MapsVision, a computer vision-based framework capable of identifying discrepancies across different map providers for similar geographical locations. In this study, we primarily focus on three map providers including: (a) Bing Maps, (b) Google Maps, and (c) OpenStreetMap. MapsVision detects textual data discrepancies such as: (1) missing location labels (2) misspelled or different keywords, (3) shifted labels, and (4) level of significance manifested by text or label font-size and color. For a given location, our MapsVision framework compares textual labels based on a ground truth entered manually to those that exist in the three map providers. We then use the results of the textual extraction to determine the accuracy of textual data appearing on map providers. Our framework intelligently identifies the set of techniques for each map providers' that can maximize the overall detection accuracy. MapsVision is composed of three main building blocks including: (a) a capturing module that captures map tiles from map providers, (b) an analysis tool that uses computer vision and text-analytic techniques, and (c) a rich visualization interface for displaying statistical and real-time analytics. The objective of MapsVision is to help map editors improve the textual quality of their maps compared to other map providers.","Title: PIES-ME '22: 1st Workshop on Photorealistic Image and Environment Synthesis for Multimedia Experiments\nYear: 2022\n\nAbstract: ABSTRACTPhotorealistic media aim to faithfully represent the world, creating an experience that is perceptually indistinguishable from a real world experience. In the past few years, this area has grown significantly, with new multimedia areas emerging, such as light fields, point clouds, ultra-high definition, high frame rate, high dynamic range imaging, and novel 3D audio and sound field technologies. In spite of all the advances done so far, there are several technological challenges to overcome. In particular, research in this field typically requires the use of big datasets, software tools, and powerful infrastructures. Among these, the availability of meaningful datasets, with a diverse and high-quality content, is of significant importance and, to date, most available datasets are limited and do not provide researchers adequate tools to advance the area of photorealistic applications. To help advancing research efforts in this area, this workshop aims to engage experts and researchers on the synthesis of photorealistic images and/or virtual environments, particularly in the form of public datasets, software tools, or infrastructures, for not only multimedia systems research, but also for other fields, such as machine learning, robotics, computer vision, mixed reality, and virtual reality."],"string":"[\n \"Title: A Distributed Protocol for Dynamic Address Assignment in Mobile Ad Hoc Networks\\nYear: 2006\\n\\nAbstract: A Mobile Ad hoc NETwork (MANET) is a group of mobile nodes that form a multihop wireless network. The topology of the network can change randomly due to unpredictable mobility of nodes and propagation characteristics. Previously, it was assumed that the nodes in the network were assigned IP addresses a priori. This may not be feasible as nodes can enter and leave the network dynamically. A dynamic IP address assignment protocol like DHCP requires centralized servers that may not be present in MANETs. Hence, we propose a distributed protocol for dynamic IP address assignment to nodes in MANETs. The proposed solution guarantees unique IP address assignment under a variety of network conditions including message losses, network partitioning and merging. Simulation results show that the protocol incurs low latency and communication overhead for an IP address assignment.\",\n \"Title: MAC-Layer Scheduling in Cognitive Radio based Multi-Hop Wireless Networks\\nYear: 2006\\n\\nAbstract: Cognitive radios CR have the ability to dynamically adapt to local spectrum availability. In a multi-hop wireless network comprised of CR-enabled devices, Medium Access Control (MAC) layer scheduling for data communication involves assignment of timeslots and channels to either links or nodes in the network. The number of channels available and the channel identities vary from one node to another within the CR network. This is in contrast to the existing use of multiple channels where all the nodes have the same set of channels available (for example in IEEE 802.11 networks). In this paper, we present an Integer Linear Programming (ILP) formulation for the MAC-layer scheduling problem and find an optimal schedule. We also propose a simple and efficient distributed heuristic for MAC-layer scheduling. Simulation results indicate that the proposed distributed heuristic provides near optimal schedule.\",\n \"Title: Improving the Performance of Hybrid Wireless Mesh Protocol\\nYear: 2012\\n\\nAbstract: Recently, IEEE 802.11s has been ratified as an amendment to the IEEE 802.11 standard. It adds the ability to establish a wireless mesh network. The amendment makes provisions for a routing protocol called Hybrid Wireless Mesh Protocol(HWMP). In this paper we study the impact of asymmetric bidirectionallinks on the performance of HWMP. We show through experiments using real hardware on a test bed and the open80211simplementation of HWMP that such links significantly impact the performance of the protocol. We describe in detail the cause of decline in performance and attribute it to implementation issues and more importantly the inadequacy of the routing metric. Moreover, we propose solutions to the identified problems, implement those solutions by making modifications to the Linux kernel mac80211 stack and show the achieved performance gains through detailed experiments.\",\n \"Title: A Biased Random Walk Routing Protocol for Wireless Sensor Networks: The Lukewarm Potato Protocol\\nYear: 2010\\n\\nAbstract: Low-latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper, we first study the lowest latency path problem, i.e., the characteristics of a path with minimum delay that connects a source node to the sink under random duty cycling nodes. Then, we propose a forwarding protocol based on biased random walks, where nodes only use local information about neighbors and their next active period to make forwarding decisions. We refer to this as lukewarm potato forwarding. Our analytical model and simulation experiments show that it is possible to reduce path latency without significantly increasing the number of transmissions (energy efficiency) needed to deliver the message to the destination. In particular, although deviating from the shortest path requires additional transmissions, and hence, higher energy consumption, this increase is compensated by a lighter duty cycle. Our experiments show that, overall, we can save up to 15 percent of energy while obtaining the same data delivery delay as shortest path routing. Additionally, the proposed solution is tunable. By changing the value of just one threshold parameter, it can be tuned to operate anywhere in the continuum from hot potato/random walk forwarding protocol to a deterministic shortest path forwarding protocol.\",\n \"Title: Designing communication strategies for hetereogeneous parallel systems\\nYear: 1998\\n\\nAbstract: This paper investigates communication strategies for interconnecting heterogeneous parallelsystems. As the speed of processors and parallel systems keep on increasing over the years, electronicinterconnections like HIPPI and FDDI are reaching their limit to provide heterogeneousparallel computing environment. This paper explores the suitability of the emerging passivestar-coupled optical interconnection using wavelength division multiplexing as the system interconnectto provide high...\",\n \"Title: Issues in Message Passing for a Tele-immersive Experience\\nYear: 2001\\n\\nAbstract: Tele-immersion is one of the applications being developed in conjunction with the Internet-2 initiative.Most of the research in this area has focused on issues pertaining to image acquisition and display,tracking technologies, robotics,haptics,etc.In order to maintain consistency of a tele-immersive experience one also needs to develop a suit of solutions that will ensure proper coordination between the participants.This will require protocols for real-time causal delivery of messages while maintaining the privacy of conversations and preventing forgery of message contents.This paper discusses these issues while considering a tele-immersive environment as a distributed message passing system.\",\n \"Title: A Dynamic Approach To Location Management In Mobile Computing Systems\\nYear: 1996\\n\\nAbstract: Managing location information of mobile nodes is an important issue in mobile computing systems. There is a trade-off between location update effort (when a node moves) and node finding effort. In this paper we present a dynamic location management strategy that has the following features (i) all location servers need not maintain location information about every mobile node, (ii) a coterie based approach is adopted for location update and find, (iii) every node move does not result in location updates, (iv) location updates are done at a subset of location servers, (v) a subset of location servers are queried when a mobile node is to be located, (vi) the set of location servers, corresponding to a mobile node, for location update and find operations is dynamic, (vii) the dynamic nature of these sets helps alleviate situations of heavy burden on some location servers, when a large number of mobile nodes are concentrated in a small geographical area. Thus, location management is done efficiently, and responsibility is shared fairly among location servers.\",\n \"Title: Slotted-FIFO Communcation for Asynchronous Distributed Systems\\nYear: 1998\\n\\nAbstract: Communication protocols designed for database applications are not necessarily suitable for other applications, like multimedia communication, due to the former's requirement of reliable and ordered communication, and the latter's ability to withstand occasional losses and misordering of messages as long as real-time communication can be supported. This paper presents the slotted-FIFO communicatio...\",\n \"Title: Lukewarm potato forwarding: a biased random walk routing protocol for wireless sensor networks\\nYear: 2009\\n\\nAbstract: Low latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper we firstly study the lowest latency path problem, i.e., the characteristics of path with minim delay that connect a source node to the sink under random duty cycling nodes. Then, we propose a forwarding protocol based on biased random walks, where nodes only use local information about neighbors and their next active period to make forwarding decisions. We refer to this as lukewarm potato forwarding. Our analytical model and simulation experiments show that it is possible to reduce path latency without significantly increasing the number of transmissions (energy efficiency) needed to deliver the message to the destination. Additionally, the proposed solution is tunable. By changing the value of just one threshold parameter it can be tuned to operate anywhere in the continuum from hot potato/random walk forwarding protocol to a deterministic shortest path forwarding protocol.\",\n \"Title: Ieee 802.11 Dcf Performance Evaluation Using One-Dimensional Discrete Time Chains\\nYear: 2006\\n\\nAbstract: Previously proposed analytical studies for IEEE 802.11 Distributed Coordination Function model the behavior of a wireless station operating under saturation conditions as a two-dimensional discrete time Markov chain. In this document, we show that the two-dimensional chain can be partitioned into two one-dimensional chains. Such a partitioning not only simplifies the analysis, but also significantly reduces the number of state variables.\",\n \"Title: FAROES: Fairness And Reliability using Overlay Expenseless Set-out for Duty-cycle Optimization in WSN\\nYear: 2009\\n\\nAbstract: Wireless sensor networks (WSNs) consist of a large number of enti- ties that collaborate in order to provide given services. Unfortunately, due to their tiny size, these entities cannot be equipped with a long-life battery. In order to minimize overall energy consumption and maximize the lifetime of the network a widely accepted approach is to implement a duty cycle. Specifically, in order to save battery life, sensors are not active all the time, and switch off their capabili- ties according to a specific schedule. In this paper, we propose a generic method to schedule these duty-cycles, taking into account two important challenges in WSNs : strong reliability of the net- work and fairness between sensors. To achieve these aims, we ensure reliability by deploying several k-connected overlays, which became active one after the other. The fairness rule is ensured by spreading the sensors into overlay accord- ing to specific characteristics as energy consumption, network density, etc. We then propose different heuristics and probability models to achieve our outcome, and finally evaluate them through simulation experiments.\",\n \"Title: Information Dissemination in Partitionable Mobile Ad Hoc Networks\\nYear: 1999\\n\\nAbstract: Ad hoc wireless networks have no wired component, and may have unpredictable mobility pattern. Such networks can get partitioned and reconnected several times. One possible approach for information dissemination in such networks is to replicate information at multiple nodes acting as repositories, and employ quorum based strategies to update and query information. We propose three such strategies that also use local knowledge about the reachability of repositories to judiciously select quorums. The primary goal is high availability of information in the face of network partitioning. We also consider four policies to determine the appropriate time to perform updates. Experimental results indicate that a hybrid information management strategy and an absolute connectivity-based update trigger policy are most suited for partitionable ad-hoc networks.\",\n \"Title: An adaptive causal ordering algorithm suited to mobile computing environments\\nYear: 1997\\n\\nAbstract: Causal message ordering is required for several distributed applications. In order topreserve causal ordering, only direct dependency information between messages, withrespect to the destination process(es), need be sent with each message. By eliminatingother kinds of control information from the messages, the communication overheadscan be significantly reduced. In this paper we present an algorithm that uses thisknowledge to efficiently enforce causal ordering of messages. The proposed...\",\n \"Title: Variable Power Broadcasting In Ad Hoc Networks\\nYear: 2006\\n\\nAbstract: Network wide broadcast is a frequently used operation in ad hoc networks and consumes significant amount of energy. Reducing the overall power consumption is extremely important in increasing the longevity of ad hoc networks. As a result, developing energy efficient broadcast operations becomes an important issue in ad hoc networks. In this paper, we propose an adaptive power broadcast algorithm that uses localized information in ad hoc networks. Our algorithm uses a novel technique to improve energy efficiency in network wide broadcast. Our simulation based comparisons show the superiority of our algorithm compared to other approaches.\",\n \"Title: Broadcast with Time and Causality Constraints for Multimedia Applications\\nYear: 1996\\n\\nAbstract: : \\\\Delta-causal ordering is a communication abstraction designed for distributed applicationswhose messages (i) have to be delivered according to causal ordering and (ii) have a limited lifetimeafter which their data can no longer be used by the application. Example of such applications are:multimedia real-time collaborative applications and groupware real-time applications. For such applications,the broadcasting of information is of primary importance. In this paper, we propose a simple...\",\n \"Title: ASSERT: Advanced wireleSS Environment Research Testbed\\nYear: 2009\\n\\nAbstract: Software simulation has often been used to evaluate proposed protocols for wireless devices. Simulation allows for rapid development and testing, but does not provide a realistic RF environment. To compensate for this, field experiments are performed. However, problems encountered during field experiments can be difficult to locate and correcting problems on-site can be time-consuming. Emulations attempt to provide the advantages of simulation and field experiments without the suffering the disadvantages of both. This demo provides an overview of the hardware, software, and emulation capabilities of ASSERT, an emulation testbed.\",\n \"Title: Low-Cost Checkpointing and Failure Recovery in Mobile Computing Systems\\nYear: 1996\\n\\nAbstract: A mobile computing system consists of mobile and stationary nodes, connected to each other by a communication network. The presence of mobile nodes in the system places constraints on the permissible energy consumption and available communication bandwidth. To minimize the lost computation during recovery from node failures, periodic collection of a consistent snapshot of the system (checkpoint) is required. Locating mobile nodes contributes to the checkpointing and recovery costs. Synchronous snapshot collection algorithms, designed for static networks, either force every node in the system to take a new local snapshot, or block the underlying computation during snapshot collection. Hence, they are not suitable for mobile computing systems. If nodes take their local checkpoints independently in an uncoordinated manner, each node may have to store multiple local checkpoints in stable storage. This is not suitable for mobile nodes as they have small memory. This paper presents a synchronous snapshot collection algorithm for mobile systems that neither forces every node to take a local snapshot, nor blocks the underlying computation during snapshot collection. If a node initiates snapshot collection, local snapshots of only those nodes that have directly or transitively affected the initiator since their last snapshots need to be taken. We prove that the global snapshot collection terminates within a finite time of its invocation and the collected global snapshot is consistent. We also propose a minimal rollback/recovery algorithm in which the computation at a node is rolled back only if it depends on operations that have been undone due to the failure of node(s). Both the algorithms have low communication and storage overheads and meet the low energy consumption and low bandwidth constraints of mobile computing systems.\",\n \"Title: Effects of link stability and directionality of motion on routing algorithms in MANETs.\\nYear: 2000\\n\\nAbstract: Most of the routing protocols proposed for Mobile Ad Hoc Networks (MANETs) rely on caching routes to increase the speed and reduce the cost of route discovery. These protocols assume high path stability between the mobile nodes in the network. This paper studies persistence of paths under various mobility patterns and network sizes. The conclusions drawn from this study enable us to determine the effectiveness of caching and also to suggest suitable caching durations. The simulation experiments indicate that path persistence declines with increasing network density and diameter. Restricting the motion of nodes increases path persistence while also increasing network partitioning. Hence, caching of routes in mobile ad hoc networks appears to have serious scalability problems.\",\n \"Title: Adaptive Ieee 802.11 Dcf Scheme With Knowledge-Based Backoff\\nYear: 2005\\n\\nAbstract: The IEEE 802.11 Distributed Coordination Function (DCF) does not require tire presence of a central controller (access point). It is based on carrier sense multiple access with collision avoidance and binary exponential backoff. While performing the backoff procedure, nodes monitor the state of tire medium and.f counter when channel is sensed busy. Under freeze backof saturation conditions, theoretical throughput limit achievable by the DCF scheme was presented in [4]. It was shown that DCF operated very far from the theoretical limit due to increased time for negotiating channel access. An enhancement to the DCF scheme so that it achieves tire theoretical limit was also presented. However, tire solution requires tire knowledge of number of nodes contending for the shared medium, which is difficult to predict in the absence of a central controller. Slow contention window decrease (SD) scheme [9] modifies the backoff procedure in DCF to improve its performance under saturation conditions. However, the SD scheme uses only a part of tire available channel state information.Additional knowledge available to nodes about tire number of collisions and freezes experienced in the recent past can be used to determine contention for tire medium more accurately. In this paper, we present an adaptive DCF (ADCF) scheme that adapts its backoff procedure based on such knowledge. Through simulation experiments, we compare tire performance of ADCF with that qf DCF and SD. Under saturation conditions, we observe that both DCF and SD operate far from the theoretical throughput limit due to their inabilily to negotiate contention for the medium quickly. By making use of the additional knowledge, the proposed ADCF scheme operates closer to the theoretical limit. For example, when DCF and SD respectively operate 35% and 20% below tire theoretical throughput limit, ADCF operates only 10% below the theoretical limit. Moreover, by recording the channel state information observed during the recent past, ADCF is also able to batter respond to tire variations in the offered traffic.\",\n \"Title: Variable power broadcast using local information in ad hoc networks\\nYear: 2008\\n\\nAbstract: Network wide broadcast is a frequently used operation in ad hoc networks. Developing energy efficient protocols to reduce the overall energy expenditure in network wide broadcast can contribute toward increasing the longevity of ad hoc networks. Most of the existing work in energy efficient broadcast protocols use either a fixed transmission power model or assume global knowledge of the entire network at each node. Variable power broadcast with local knowledge has recently been proposed as a promising alternative approach for network wide broadcast in ad hoc networks. In this paper, we present a novel approach, called INOP, for network wide broadcast. INOP is a variable power broadcast approach that uses local (two-hop neighborhood) information. INOP utilizes a novel technique for determining the transmission power level at each transmitting node. We also propose two alternative methods to cover the nodes that are not covered by the transmission of the source or a retransmitting node. Our simulation based evaluations show that, compared to other approaches, INOP achieves better results in terms of energy efficiency, and competes with and exceeds other approaches in terms of a number of other performance metrics including traffic overhead, coverage, and convergence time. Based on these results, we can conclude that INOP improves the current state-of-the-art approaches for energy efficient broadcast in ad hoc networks.\",\n \"Title: Continuous Active Phase Shifter Design and Analysis for Millimeter-Wave Circuits.\\nYear: 2013\\n\\nAbstract: This brief presents a continuous active phase shifter for millimeter-wave phased-array transceivers. Having an all-pass network frequency response, the proposed phase shifter provides continuous insertion phase control and nearly constant insertion loss regardless of the insertion phase variation. A complete analysis for the phase shifter is provided along with circuit measurement results. The pha...\",\n \"Title: \\\"RF in the Jungle\\\": effect of environment assumptions on wireless experiment repeatability\\nYear: 2009\\n\\nAbstract: Most researchers conduct wireless networking experiments in their laboratory or similar indoor environments. Such environments are veritable RF jungles, especially when we consider the ISM bands. In this paper we examine and test several common explicit and implicit assumptions that researchers tend to make about the wireless environment. Although these assumptions are acknowledged by most researchers, the extent of their impact is often underestimated. We find that because the environment is always in flux, it is almost impossible to reproduce the results of an experiment. Hence, there is a high risk of misinterpreting the data obtained from such experiments. Through this paper we try to caution experimenters against such risky assumptions when they venture into the RF jungle. After a successful proof-of-concept experiment, we advocate the use of wireless networking testbeds that provide experimenters better control over the RF environment by using coaxial cables, programmable attenuators and power dividers/combiners.\",\n \"Title: Parallel and Gaussian frequency hopping for dynamic coexistence in the unlicensed band\\nYear: 2011\\n\\nAbstract: With the surge of short-range wireless applications, more networks are being deployed in the unlicensed radio band. The challenge that emerges is to accommodate these networks without breaching current rules and regulations on frequency usage. This paper studies the coexistence of several independent and dynamic wireless networks using the frequency hopping technique. We propose a novel hopping scheme that minimizes mutual interference and allows more networks to collocate effectively, but does not violate restrictions imposed by the Federal Communications Commission (FCC) regarding frequency constraint (related to the minimum number of frequencies in a hopping set) and time constraint (related to the maximum duration of using a particular frequency). The coexisting networks follow the Gaussian distribution in choosing transmission frequencies from parallel hopping spaces without the overhead of extra message exchange among networks. Simulation results on key metrics such as channel collision rate, goodput, and fairness in channel usage are presented to establish the viability of the proposed scheme in comparison with other contemporary approaches. Copyright © 2011 John Wiley & Sons, Ltd. (This work has been supported in part by the National Science Foundation (NSF) under grant no. CNS-0435105. A preliminary and partial presentation of this study has appeared in the proceedings of IEEE International Conference on Communications (ICC), Dresden, Germany, June 2009.)\",\n \"Title: Architecture for Group Communication in Mobile Systems\\nYear: 1998\\n\\nAbstract: In mobile computing systems the network configuration changes due to node mobility. This paper identifies the issues a group communication service has to take into account in order to handle node mobility. These include the need to identify the location of a node, and the ability to cope with inaccuracies in the determination of a group membership. A multi-level architecture for group communication in mobile systems is presented. This architecture contains a synchronous proximity layer protocol to determine the set of mobile nodes in the proximity of a given node in the network. This information is used by a three-round group membership protocol for construction of groups used by mobile applications. As an example, the architecture is specialized to solve the channel allocation problem.\",\n \"Title: Link scheduling in wireless sensor networks: Distributed edge-coloring revisited\\nYear: 2008\\n\\nAbstract: We consider the problem of link scheduling in a sensor network employing a TDMA MAC protocol. Our algorithm consists of two phases. The first phase involves edge-coloring : an assignment of a color to each edge in the network such that no two edges incident on the same node are assigned the same color. Our main result for the first phase is a distributed edge-coloring algorithm that needs at most ( Δ + 1 ) colors, where Δ is the maximum degree of the network. To our knowledge, this is the first distributed algorithm that can edge-color a graph using at most ( Δ + 1 ) colors. The second phase uses the edge-coloring solution for link scheduling . We map each color to a unique timeslot and attempt to assign a direction of transmission along each edge such that the hidden terminal problem is avoided; an important result we obtain is a characterization of network topologies for which such an assignment exists. Next, we consider topologies for which a feasible transmission assignment does not exist for all edges, and obtain such an assignment using additional timeslots. Finally, we show that reversing the direction of transmission along every edge leads to another feasible direction of transmission. Using both the transmission assignments, we obtain a TDMA MAC schedule which enables two-way communication between every pair of adjacent sensor nodes. For acyclic topologies, we prove that at most 2 ( Δ + 1 ) timeslots are required. Results for general topologies are demonstrated using simulations; for sparse graphs, we show that the number of timeslots required is around 2 ( Δ + 1 ) . We show that the message and time complexity of our algorithm is O ( n Δ 2 + n 2 m ) , where n is the number of nodes and m is the number of edges in the network. Through simulations, we demonstrate that the energy consumption of our solution increases linearly with Δ . We also propose extensions to account for non-ideal radio characteristics.\",\n \"Title: Csma-Based Mac Protocol For Cognitive Radio Networks\\nYear: 2007\\n\\nAbstract: Cognitive radios (CR) technology enables wireless devices to dynamically switch between channels in a wide range of frequency bands and utilize unused parts of licensed and unlicensed frequency bands. The CR-enabled devices can either form a stand-alone multi-hop wireless network or form a multi-hop wireless backbone network that can connect different types of devices together. In a multi-hop wireless network composed of CR-enabled devices the number and the set of available channels vary from one node to another. This is in contrast to the existing multi-hop wireless mesh networks where all the nodes have the same set of channels available. In this paper we present a CSMA-based MAC protocol for CR-based multihop network. This protocol is based on the channel segregation technique proposed for cellular networks. Simulation results indicate that the protocol incurs low latency and achieves reasonable throughput.\",\n \"Title: Dependency sequences and hierarchical clocks: efficient alternatives to vector clocks for mobile computing systems\\nYear: 1997\\n\\nAbstract: Vector clocks have been used to capture causal dependencies between processes in distributed computing systems. Vector clocks are not suitable for mobile computing systems due to (i) lack of scalability: its size is equal to the number of nodes, and (ii) its inability to cope with fluctuations in the number of nodes. This paper presents two efficient alternatives to vector clock, namely, sets of dependency sequences, and hierarchical clock. Both the alternatives are scalable and are immune to fluctuations in the number of nodes in the system.\",\n \"Title: Reliable multicast in mobile networks\\nYear: 2003\\n\\nAbstract: This paper describes a distributed algorithm for reliable multicast in mobile cellular networks. In the proposed solution the multicast message is flooded to all the base stations over reliable channels. The base stations then collectively ensure that all mobile nodes belonging to the multicast group get the message. The originality of our solution is that it is fully decentralized. Each base station can independently decide when to flush a message from its buffer. Even if a node moves from one cell to another while a multicast is in progress, delivery of the message to the node is guaranteed. Simulation experiments show that using the proposed solution, memory requirements at the base stations are significantly smaller than by using centralized solutions.\",\n \"Title: Time-Efficient Layer-2 Auto-Configuration for Cognitive Radios\\nYear: 2005\\n\\nAbstract: timeslots, where is the maximum number of nodes deployed, is the maximum number of available channels for communication and is the diameter of the network. Assuming all nodes are aware of and , we present both diameter-aware and diameter-unaware versions of the algorithm. For highly sparse networks like linear chain topology where , with and , the diameter- aware conguration protocol terminates within and the diameter-unaware version terminates within .\",\n \"Title: ATR-MAC: deadline driven data collection from smartmeters in absence of aggregation\\nYear: 2013\\n\\nAbstract: Deployment of Smart Grid networks throughout cities introduces a realistic scenario for a large scale sensor network. Smart Meters create a wireless mesh network for receiving commands and sending metering reports back to provider company. The challenges of reliable and timely communication call for a fresh review of the well studied topic of Wireless Sensor Networks (WSN). We provide a centralized MAC solution for data collection, ATR-MAC, that relaxes requirements in general purpose WSNs, but emphasizes on difficulties a Smart Metering deployment will face. ATR-MAC considers variable reuse distances for minimizing propagation delay. It also increases efficiency of collection deadline instead of energy efficiency, a common concern of general-purpose WSN MAC protocols. We provide time and buffer size analysis of our algorithm, prove its correctness and show experimental results using implementation on a testbed.\",\n \"Title: Time-efficient distributed layer-2 auto-configuration for cognitive radio networks\\nYear: 2008\\n\\nAbstract: Cognitive radios (CR) have the ability to dynamically adapt to local spectrum availability. In a network comprised of CR-enabled devices, layer-2 auto-configuration involves determining a common set of channels to facilitate communication among participating nodes. This is a unique challenge as nodes in the CR network may be unaware of (a) their neighbors and (b) the channels on which they can communicate with a neighbor. In this paper, we propose a time-efficient distributed algorithm for layer-2 auto-configuration for a CR network. Our algorithm finds the globally common channel set in 2MN+O(DN) timeslots, where each node is assigned a unique identifier from the range [1,...,N], M is the maximum number of channels available for communication, and D is the diameter of the network. All nodes know M and N. We present both diameter-aware and diameter-unaware versions of the algorithm. We then show that the proposed algorithms are efficient by proving a matching lower bound. Finally, we investigate a special case when nodes have more knowledge available at their disposal and discuss how the time-complexity of our algorithm can be improved under this case.\",\n \"Title: Max-Min D-Cluster Formation in Wireless Ad Hoc Networks\\nYear: 2000\\n\\nAbstract: An ad hoc network may be logically represented as a set of clusters. The clusterheads form a -hop dominating set. Each node is at most hops from a clusterhead. Clusterheads form a virtual backbone and may be used to route packets for nodes in their cluster. Previous heuristics restricted themselves to -hop clusters. We show that the minimum -hop dominating set problem is NP-complete. Then we present a heuristic to form -clusters in a wireless ad hoc network. Nodes are assumed to have non-deterministic mobility pattern. Clusters are formed by diffusing node identities along the wireless links. When the heuristic terminates, a node either becomes a clusterhead, or is at most wireless hops away from its clusterhead. The value of is a parameter of the heuristic. The heuristic can be run either at regular intervals, or whenever the network configura- tion changes. One of the features of the heuristic is that it t ends to re-elect existing clusterheads even when the network configuration c hanges. This helps to reduce the communication overheads during transition from old clusterheads to new clusterheads. Also, there is a tendency to evenly dis- tribute the mobile nodes among the clusterheads, and evently distribute the responsibility of acting as clusterheads among all nodes. Thus, the heuristic is fair and stable. Simulation experiments demonstrate that the proposed heuristic is better than the two earlier heuristics, namely the LCA (1) and Degree based (11) solutions.\",\n \"Title: Emulation of multipath effects on a wireless testbed and its impact on MAC layer performance\\nYear: 2012\\n\\nAbstract: Field experiments are an important part of research in wireless networks. Since the wireless channel varies with location and time, the results vary for the same field experiment at a different place and time. Assumptions about the wireless environment can lead to biased results. It is necessary to shield wireless transmission from uncontrolled interference in order to make the experiment repeatable. This paper describes $$\\\\underline{A}$$ dvanced wirele $$\\\\underline{SS}$$ $$\\\\underline{E}$$ nvironment $$\\\\underline{R}$$ esearch $$\\\\underline{T}$$ estbed (ASSERT) which uses shielded co-axial cables as the communication media for radio signals to conduct reliable, scalable and accurate wireless experiments. Shielding the transmission also protects the signal from random burst of noise introduced by the environment. The paper describes how the combination of programmable attenuators and RF splitters/combiners, which are part of ASSERT, helps in emulating complex and varying environments including those in which multipath interference plays a significant role. Our experimental results indicate that (1) tweaking the MAC layer and retransmissions at the application layer neutralize, to an extent, the impact of multipath effects when the received signal strength is extremely good, and (2) when the received signal strength falls below a certain threshold multipath interference plays a significant role.\",\n \"Title: Optimal control problem for the time-dependent Kirchhoff-Love plate in a domain with rough boundary.\\nYear: 2013\\n\\nAbstract: In this paper, we study the asymptotic behavior of an optimal control problem for the time-dependent Kirchhoff-Love plate whose middle surface has a very rough boundary. We identify the limit problem which is an optimal control problem for the limit equation with a different cost functional.\",\n \"Title: The impact of mobility on the time complexity for deterministic broadcasting in radio networks\\nYear: 2011\\n\\nAbstract: We study the time complexity for deterministic broadcasting algorithms in mobile radio networks. The broadcast operation consists of a source node successfully communicating its message to every other node. In multi-hop radio networks such as MANETs, the message may traverse multiple other nodes. Nodes have no prior knowledge besides the number n of nodes in the network and its diameter D. The problem we address has been extensively studied for static networks. Our work quantifies the impact of mobility. We consider three families of graphs: undirected graphs of constant contention degree, undirected graphs of non-constant contention degree and directed graphs of non-constant contention degree. We prove the lower bounds of Ω(n log n) time slots for the first family, Ω(n²/D² log D + D) time slots for the second and Ω(n²/D² log D + n log D) for the third. At the time of writing, the corresponding tightest lower bounds derived in the static case are, respectively, Ω(D log n), Ω(n log/log n / D) and Ω(n log D).\",\n \"Title: Dynamic coexistence of frequency hopping networks using parallel and Gaussian allocations\\nYear: 2009\\n\\nAbstract: This paper studies the coexistence of several independent and dynamic wireless networks using the frequency hopping technique in the unlicensed radio band. We propose a new hopping scheme that allows more networks to collocate effectively, but does not violate federal restrictions regarding frequency constraint (related to the minimum number of frequencies in a hopping set) and time constraint (related to the maximum duration of using a particular frequency). The coexisting networks follow the Gaussian distribution in choosing transmission frequencies from parallel hopping spaces without the overhead of extra message exchange. Simulation results include comparison with other contemporary approaches and establish the viability of the proposed scheme.\",\n \"Title: On the relative speed of messages and hierarchical channels\\nYear: 1992\\n\\nAbstract: The authors study the concept of relative speed of messages and a hierarchy of such speeds which results in a hierarchical channel. They present examples of applications where hierarchical channels are useful and an implementation of such a channel using selective flooding. They describe a mechanism that permits a programmer to specify a partial order among channels, and compare the hierarchical channels with F-channels.\",\n \"Title: A routing algorithm for wireless ad hoc networks with unidirectional links\\nYear: 2001\\n\\nAbstract: Most of the routing algorithms for ad hoc networks assume that all wireless links are bidirectional. In reality, some links may be unidirectional. In this paper we show that the presence of such links can jeopardize the performance of the existing distance vector routing algorithms. We also present modifications to distance vector based routing algorithms to make them work in ad hoc networks with unidirectional links. For a network of n nodes, neighbors exchange n x n matrices to propagate routing information. This results in loop-free routes.\",\n \"Title: A QoS-aware MAC layer protocol for wireless LANs\\nYear: 2004\\n\\nAbstract: With advances in physical layer technologies, WLANs are now connected with wired networks and act as parts of the entire networks. Since demands for QoS sensitive applications are extremely high, WLANs, as parts of heterogeneous networks, are required to be QoS-aware. In this paper we present a new QoS-aware multi-access scheme, called ADCF, designed to assure weighted fair queuing in a purely distributed way and to achieve admission control per frame. The results of simulations show that ADCF yields stable weighted fair queuing with consistent performance under most conditions. In most cases, ADCF outperforms DCF of IEEE 802.11 and EDCF of IEEE 802.11e. Also, ADCF guarantees starvation free channel access for a low priority flow.\",\n \"Title: Enhancing ASSERT: making an accurate testbed friendly\\nYear: 2011\\n\\nAbstract: This article discusses lessons learned from use of our publicly available wireless networking testbed, assert[1]. In [1] we discussed the design and implementation phase of a testbed based on a set of propositions. By opening the testbed to users not familiar with underlying architecture of assert, we put these propositions to the test. While fidelity of the testbed is a major challenge for developers, users assume the fidelity as a given and look for ease of use comparable with a simulator. We list the main demands by users of our testbed and the way we addressed these demands during an enhancement phase.\",\n \"Title: Overload-state downlink resource allocation in LTE MAC layer\\nYear: 2013\\n\\nAbstract: This paper presents a quality of service-aware resource scheduling algorithm targeted for downlink traffic in the UMTS Long-Term Evolution Medium Access Control layer with emphasis for support in an overload state. Specifically, multiple real-time traffic metrics including latency, loss, and queue depth are normalized and processed via an array of ranking functions and multiplexed into an aggregate rank. This aggregate rank is then used in a fractional knapsack scheduling implementation. Experiments with this scheduling mechanism show improved traffic processing intelligence over existing scheduling models, especially in overload states.\",\n \"Title: Causality and the Spatial-Temporal Ordering of Events in Mobile Systems\\nYear: 1999\\n\\nAbstract: Several mobile computing applications require that both the order of occurrence of events, and the location of their occurrence, be taken into account during decision making. Thus, processes need to track the location of nodes and synchronize their clocks. In this paper we present a framework, based on the capabilities of Global Positioning System, which provides processes with a global virtual clock and a positioning service. We introduce then the notion of space-time vector used by processes to track the mobility of nodes.\",\n \"Title: Fault Tolerant Mobility Planning for Rapidly Deployable Wireless Networks\\nYear: 1998\\n\\nAbstract: Rapidly deployable wireless networks consist of mobile base stations and less powerful mobile hosts. The mobile base stations have to maintain wireless connectivity while on the move along pre-defined paths. Physical obstructions and wireless range limitations may prevent a pair of mobile base stations from establishing a wireless link. We study situations of distance-constrained mobility, and fault situations like distance and topology induced mobility deadlocks. We also propose a deadlock avoidance mobility scheme using repeaters, and derive an upper bound on the number of repeaters. We propose two heuristics, using sleeper nodes, for providing coverage to areas that may lose coverage due to a mobile base station crash.\",\n \"Title: Wireless Data Center with Millimeter Wave Network\\nYear: 2010\\n\\nAbstract: Data centers are becoming increasingly popular for a wide variety of applications such as search, gaming, email and so on. The complex wiring issues in data centers have motivated us to consider a wireless solution for data centers which meets the design goals of a typical data center network while providing the additional benefit of flexibility in the network. The wireless data center is based on the recently released IEEE 802.15.3c wireless networking standard in the 60 GHz ISM band. The standard supports multi-Gbps data rates and enables the transceivers to set up point-to-point links with each other, which makes it suitable for data center interconnects. In this paper, we use 60 GHz wireless technology to design a wireless data center and show how various data center interconnects such as 3-tier and fat-tree can be emulated on such a wireless network.\",\n \"Title: Aggressive Error Recovery for TCP over wireless links\\nYear: 2000\\n\\nAbstract: TCP's congestion control handless packet loss due to congestion in the network. Over wireless links, packet loss may also be due to signal fading. Wireless LAN traffic under High Bit Error rate (BER) suffers great throughput degradation due to the current congestion control mechanism. Our algorithm allows TCP to send as much data as possible within a threshold that optimizes throughput while recovering from a high BER on a wireless LAN link. We will refer to the error recovery mechanism as Aggressive Error Recovery (AER) and call the new TCP version as TCP Noor.\",\n \"Title: Exploring Alternatives to Channel Change for Improving the Coexistence of IEEE 802.15.4 and IEEE 802.11\\nYear: 2012\\n\\nAbstract: The recent increase in the number of technologies operating in the 2.4GHz ISM band has drawn attention towards the impact they can have on each other. In this paper, we have conducted a case study about coexistence of IEEE 802.11and IEEE 802.15.4 which has led us to discover previously unknown interactions. We have performed experiments using real hardware to evaluate the impact of IEEE 802.11 on IEEE 802.15.4 and vice versa. More importantly, we have identified IEEE 802.11MAC/PHY layer parameters that could be changed in order to improve the performance of coexisting IEEE 802.15.4 nodes. We have also identified the order in which these adjustments should be made.\",\n \"Title: Reliable Broadcast in Wireless Mobile Ad Hoc Networks\\nYear: 2006\\n\\nAbstract: We propose a single source reliable broadcasting algorithm for linear grid-based networks where a message is guaranteed to be delivered to all the nodes of the network. The nodes are mobile and can move from one grid point to another. The solution does not require the nodes to know the network size or its diameter. The only information a node has is its identity and its position. On average, only a subset of nodes transmit and they transmit only once to achieve reliable broadcast. The protocol is contention-free and energy-efficient. We show that reliable broadcast can be achieved in O(Dlog n) time-slots despite node mobility, where D is the diameter of the network and n the number of nodes.\",\n \"Title: Load-balanced location management for cellular mobile systems using quorums and dynamic hashing\\nYear: 2001\\n\\nAbstract: This paper presents a new distributed location management strategy for cellular mobile systems. Its salient features are fast location update and query, load balancing among location servers, and scalability. The strategy employs dynamic hashing techniques and quorums to manage location update and query operations. The proposed strategy does not require a home location register (HLR) to be associated with each mobile node. Location updates and queries for a mobile node are multicast to subsets of location servers, which change with time depending on the location of mobile node/querying node and load on the servers. Simulation experiments demonstrate that such dynamism prevents situations of heavy load on some location servers when mobile nodes are not uniformly distributed in space, or when some mobile nodes have their location updated or queried more often than others. Also, queries return the latest location information of a mobile node with a very high probability. The proposed scheme requires at most one unicast and two rounds of message multicasting for location update and query operations. All multicast messages have a small payload and are restricted to the high bandwidth wired part of the mobile network resulting in low communication overhead. Moreover, if a quorum of location servers gets overloaded, part of its load can be transferred to another lightly loaded quorum using dynamic hashing techniques.\",\n \"Title: Droplet microfluidics for chip-based diagnostics.\\nYear: 2014\\n\\nAbstract: Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays.\",\n \"Title: Multiplex, Quantitative, Reverse Transcription PCR Detection of Influenza Viruses Using Droplet Microfluidic Technology.\\nYear: 2015\\n\\nAbstract: Quantitative, reverse transcription, polymerase chain reaction (qRT-PCR) is facilitated by leveraging droplet microfluidic (DMF) system, which due to its precision dispensing and sample handling capabilities at microliter and lower volumes has emerged as a popular method for miniaturization of the PCR platform. This work substantially improves and extends the functional capabilities of our previously demonstrated single qRT-PCR micro-chip, which utilized a combination of electrostatic and electrowetting droplet actuation. In the reported work we illustrate a spatially multiplexed micro-device that is capable of conducting up to eight parallel, real-time PCR reactions per usage, with adjustable control on the PCR thermal cycling parameters (both process time and temperature set-points). This micro-device has been utilized to detect and quantify the presence of two clinically relevant respiratory viruses, Influenza A and Influenza B, in human samples (nasopharyngeal swabs, throat swabs). The device performed accurate detection and quantification of the two respiratory viruses, over several orders of RNA copy counts, in unknown (blind) panels of extracted patient samples with acceptably high PCR efficiency (>94%). The multi-stage qRT-PCR assays on eight panel patient samples were accomplished within 35-40 min, with a detection limit for the target Influenza virus RNAs estimated to be less than 10 RNA copies per reaction.\",\n \"Title: CHAMELEON: A Framework for Coexistence of Wireless Technologies in an Unlicensed Band\\nYear: 2014\\n\\nAbstract: The recent increase in the number of technologies operating in the 2.4 GHz ISM band has drawn attention towards the impact they can have on each other. In this paper, we have conducted a case study about coexistence of IEEE 802.11 and IEEE 802.15.4 which has led us to discover previously unknown interactions. We show through extensive experiments that CCA method used by a wireless device can significantly change the coexistence scenario. We also highlight the ways in which coexistence can be improved by making runtime adjustments to some MAC/PHY layer parameters and show their effectiveness. Furthermore, we propose a framework which exploits the pervasiveness and ubiquity of Wi-Fi to improve coexistence among wireless technologies in the 2.4 GHz ISM band. Our framework has the capability to detect the presence of wireless technologies operating anywhere in the 2.4 GHz ISM band and also accounts for devices whose signatures do not exist in the database. It facilitates the Wi-Fi AP to make decisions such as changing the channel or making MAC/PHY layer adjustments which are compliant with the configured coexistence policy thus improving the performance of the wireless devices. We have implemented our framework on real hardware and evaluated its performance in the presence of ZigBee.\",\n \"Title: Proactive resource allocation optimization in LTE with inter-cell interference coordination\\nYear: 2014\\n\\nAbstract: This paper presents a distributed, dynamic self-organizing network (SON) solution for downlink resources in an LTE network, triggered by support vector regression instances predicting various traffic loads on the nodes in the network. The proposed SON algorithm pro-actively allocates resources to nodes which are expected to experience traffic spikes before the higher traffic load occurs, as opposed to overloaded nodes reacting to a resource-exhaustion condition. In addition, the solution ensures inter-cell interference coordination is maintained across the LTE cells/sectors.\",\n \"Title: Asymptotic behavior of the solutions of a degenerating elliptic equation in a thin multidomain.\\nYear: 2014\\n\\nAbstract: We study the behavior of the solutions u(epsilon) of a degenerating elliptic equation in the framework of the dimension reduction problem coupled with an oscillating boundary. Under a suitable choice of the scalings on the source term and on the diffusivity coefficients, we prove that the limit problem is a nonlocal problem involving only the diffusion through the upper part of the domain.\",\n \"Title: Maximal global snapshot with concurrent initiators\\nYear: 1994\\n\\nAbstract: In a distributed system multiple nodes may initiate snapshot collection concurrently. In this paper we present a global snapshot collection algorithm that combines the information collected by each initiator. This generates a maximal, consistent global snapshot that is more recent than the snapshot collected by any initiator. Global snapshots are used to establish checkpoints for recovery from node failures. A maximal snapshot implies that the amount of computation lost during roll-back after node failures, is minimized. We also present an efficient information dissemination strategy that nodes can employ to exchange snapshot information with each other.\",\n \"Title: Towards 60ghz Wireless Switching Interconnect\\nYear: 2013\\n\\nAbstract: In the era of cloud computing and high performance computing clusters, interconnection networks are in high demand and have many applications including data center networks. Typically, nodes of interconnects are placed in a closed room and are connected using a set of wires through one or more high-end switches with little or no reconfigurability to the interconnect. In this paper, we present a design of wireless switching interconnects using 60GHz technology. The Gigabit, point-to-point and extremely directional links in the 60GHz band are used to replace wired connections in such a network to provide flexibility and reconfigurability. We extend our previous investigation where a high level node placement technique was discussed to arrange nodes into a closed polygon. Here we present an initial design for exact arrangement and placement of the fat-tree nodes, suitable for small to medium size wireless switching interconnects. We argue that creating a completely wireless interconnect is viable, and present mathematical equations and a proof to support the claim.\",\n \"Title: Concurrency in polygonally arranged wireless Data Centers with all line-of-sight links\\nYear: 2014\\n\\nAbstract: The use of wireless links can provide flexibility and reconfigurability to data center networks. Recent investigations show that 60GHz millimeter-wave technology can be used in wireless data center networks. The steerable millimeter-wave transceiver works as a multi-port switch where point-to-point links are established using beam-forming. Considering an interference model, specific to the wireless data center, we propose a new algorithm for k-pod fat-tree data center topology mapping. Further, we propose to group all links of the network into sets of mutually concurrent links. By assigning a time slot for all concurrent links in a set, we devise a TDMA scheduling algorithm for the wireless network. We show that the concurrent wireless transmissions could result in O(k2) number of slots that is k times better than graph based coloring approach. By increasing the concurrency, we argue that the use of 60GHz technology is more viable in building completely wireless data centers.\",\n \"Title: Improving the performance of multipath TCP over heterogeneous paths using slow path adaptation\\nYear: 2014\\n\\nAbstract: Multipath TCP (MPTCP) is an extension of TCP, developed by Internet Engineering Task Force (IETF) to support communication between source and destination through multiple flows under a single connection session. We have conducted several experiments with real hardware on flows with extreme variation in path quality and found that unless receive buffer size is increased to a much higher value, the overall throughput decreases below the level of single-path TCP throughput. We propose a Slow Path Adaptation (SPA) technique to overcome this issue without affecting other performance parameters. The implementation is done on Linux kernel and experimental results are presented.\",\n \"Title: MANETconf: configuration of hosts in a mobile ad hoc network\\nYear: 2002\\n\\nAbstract: A mobile ad hoc network (MANET) is a multi-hop wireless network capable of autonomous operation. The mobility of MANET nodes can lead to frequent and unpredictable topology changes. Most MANET literature assumes that network related information of a node (such as its IP address, netmask, etc.) is configured statically, prior to the node joining the MANET. However, not all nodes have IP addresses permanently assigned to them. Such nodes rely on a centralized server and use a dynamic host configuration protocol, like DHCP (dynamic host configuration protocol), to acquire an IP address. Such a solution cannot be employed in MANETs due to the unavailability of any centralized DHCP server. In this paper, we first present a survey of possible solutions approaches, and discuss their limitations. Then, we present a distributed dynamic host configuration protocol designed to configure nodes in a MANET. We show that the proposed protocol works correctly and does not have the limitations of earlier approaches. Finally, we evaluate the performance of the solution through simulation experiments, and conclude with a discussion of related security issues.\",\n \"Title: Energy efficient schemes for wireless sensor networks with multiple mobile base stations\\nYear: 2003\\n\\nAbstract: One of the main design issues for a sensor network is conservation of the energy available at each sensor node. We propose to deploy multiple, mobile base stations to prolong the lifetime of the sensor network. We split the lifetime of the sensor network into equal periods of time known as rounds. Base stations are relocated at the start of a round. Our method uses an integer linear program to determine new locations for the base stations and a flow-based routing protocol to ensure energy efficient routing during each round. We propose four metrics and evaluate our solution using these metrics. Based on the simulation results we show that employing multiple, mobile base stations in accordance with the solution given by our schemes would significantly increase the lifetime of the sensor network.\",\n \"Title: Service differentiation mechanisms for IEEE 802.11-based wireless networks\\nYear: 2004\\n\\nAbstract: In this paper, we study two medium access control (MAC) sublayer policies, namely, Schedule After Backoff (SAB) and Schedule Before Backoff (SBB), which offer differentiated services in IEEE 802.11-based wireless networks. Both policies control channel access based on frame priorities. In the SAB policy, each node maintains concurrent backoff instances (one per priority class) with different parameter values to realize service differentiation. High-priority data frames use a shorter contention window, so that, in most cases, they are transmitted before the low-priority ones. The Enhanced Distributed Coordination Function (EDCF) scheme specified in the upcoming IEEE 802.11e standard is based on the SAB policy. Recent studies (7) have shown that under high loads of high-priority traffic, EDCF starves low-priority frames. We propose SBB policy, which provides service differentiation without the need for maintaining concurrent backoff instances. In SBB, frame transmission proceeds in two sequential steps: (i) selecting the next frame to be transmitted, and (ii) channel access functionality until the selected frame is either successfully transmitted or its number of retransmissions exceeds the retry limit. These two steps are independent and can be performed using several alternatives. Depending on the way the two steps are carried out, we present four SBB-based MAC schemes. We evaluate SAB and SBB-based MAC schemes through simulation experiments. Our simulation results show that the SBB policy does not starve low- priority traffic and offers differentiated service on par with SAB. This suggests that maintenance of concurrent backoff instances contributes little towards performance improvement. Keywords—ad hoc, DCF, IEEE 802.11e, QoS, WLANs.\",\n \"Title: Modifications to TCP for improved performance and reliable end-to-end communication in wireless networks\\nYear: 1999\\n\\nAbstract: Wireless ad-hoc networks consist of a set of identical mobile nodes that communicate with each other over limited range wireless links. These wireless links are lossy due to noise and co-channel interference. Moreover, node mobility can lead to establishment of new links and disappearance of some existing links. Current implementations of TCP are not suitably equipped to operate in ad-hoc networks. Loss of packets due to path disruption can be misinterpreted as congestion. We propose to introduce modifications to TCP such that it can work for these kind of dynamic networks. These modifications will exploit the mobility support in the underlying routing protocol. The information provided by the routing protocol can be used to send explicit freeze and resume signals to the TCP source on link disruption and restoration. The proposed solutions can inter-operate with existing TCP implementations, have low communication overheads and are consistent with various ad-hoc network routing protocols\",\n \"Title: A tunneling approach to routing with unidirectional links in mobile ad-hoc networks\\nYear: 2000\\n\\nAbstract: Mobile ad hoc networks (MANETs) consist of a set of similar mobile nodes, communicating with each other using wireless links. As a node may not be able to directly reach every other node, a packet may need to traverse multiple wireless links from its source to its destination. Unidirectional links can occur in such networks. Several existing routing protocols implicitly assume bidirectional links when making their routing decisions. Not using unidirectional links can lead to sub-optimal routes. A tunneling solution to allow efficient operation in ad hoc networks with unidirectional links is presented. The tunneling solution uses information gathered by the routing protocol to tunnel packets from the end-point of the unidirectional link to its source. A naive implementation of tunneling could lead to loops in the system and a deluge of packets. This is because when ACKs (acknowledgments) for link layer messages are tunneled across unidirectional links, ACKs for them may end up being generated recursively. The solution presented here prevents such a packet explosion from occurring\",\n \"Title: Extending Paxos/LastVoting with an Adequate Communication Layer for Wireless Ad Hoc Networks\\nYear: 2008\\n\\nAbstract: Most papers addressing consensus in wireless ad hoc networks adopt system models similar to those developed for wired networks. These models are focused towards node failures while ignoring link failures, and thus are poorly suited for wireless ad hoc networks. The recently proposed HO model does not have this drawback. The paper shows that an existing algorithm and the HO model can be used for multi-hop wireless ad hoc networks, if extended with an adequate communication layer. The description of the communication layer is augmented with simulation results that validate the feasibility of our approach and provide better understanding of the behavior of wireless environments.\",\n \"Title: Gradient-Based Aggregation in Forest of Sensors (GrAFS)\\nYear: 2011\\n\\nAbstract: In several sensing applications the parameter being sensed exhibits a high spatial correlation. For example, if the temperature of a region is being monitored, there are distinct hot and cold spots. The area close to the hot spots is usually warmer than average, with a temperature gradient between the hot and cold spots. We exploit this correlation of sensor data to form a forest of logical trees, with the trees collectively spanning all the sensor nodes. The root of a tree corresponds to a sensor reporting the local peak value. The tree nodes represent the value gradient: each node's sensed value is smaller than that of its parent, and greater than that of its children. GrAFS provides a mechanism to maintain some information at the local peaks and the sink. Using this information the sink can answer several queries either directly, or by probing the region of the sensor field that holds the answer. Thus, queries can be answered in a time and/or bandwidth efficient manner. The GrAFS approach to data aggregation can easily adapt to changes in the spatial distribution of sensed values, and also cope with message losses and sensor node failures. Implementation on MICA2 motes and simulation experiments conducted using TinyOS quantify the performance of GrAFS.\",\n \"Title: Causality and the Spatial–Temporal Ordering in Mobile Systems\\nYear: 2004\\n\\nAbstract: Several mobile computing applications require that both the order and location of occurrence of events be taken into account during decision making. Thus, processes need to track the location of nodes and synchronize their clocks. The Global Positioning System can be employed to mimic a global virtual clock that keeps the local clocks of participating nodes in synchrony with each other. The global virtual clock in conjunction with a space–time vector can track the mobility of nodes. Nodes can prioritize resource requests on the basis of request time as well as the requester's distance from the resource. Two distributed mutual exclusion algorithms that employ the space–time vector are presented. The error in the estimates of a mobile node, due to clock drift, about the region in which other mobile nodes may be present is formulated. Various resource allocation policies can react differently to such errors leading to performance differences. However, every policy should ensure that resource allocation has the properties of safety, deadlock freedom, liveness, and fairness.\",\n \"Title: Periodic Controls in an Oscillating Domain: Controls via Unfolding and Homogenization.\\nYear: 2015\\n\\nAbstract: An optimal control problem in a two-dimensional domain with a rapidly oscillating boundary is considered. The main features of this article are on two points, namely, we consider periodic controls in the thin periodic slabs of period epsilon > 0, a small parameter, and height O(1) in the oscillatory part, and the controls are characterized using unfolding operators. We then do a homogenization analysis of the optimal control problems as epsilon -> 0 with L-2 as well as Dirichlet (gradient-type) cost functionals.\",\n \"Title: On the Fidelity of Single-Machine Network Emulation in Linux\\nYear: 2015\\n\\nAbstract: Network emulation strikes the balance between using real machines on full-fledged networks and running software models of applications and networks in simulation environments. Advanced Linux features make it possible to emulate entire networks on a single machine, enabling experiments that are much easier to run and repeat. However, some of these features were not designed with the primary purpose of supporting emulation frameworks: if not carefully configured, they can lead to erroneous results. In this paper we note a few properties of Linux-based network emulation that researchers should consider while planning their experiments. We also recommend a particular configuration that improves the fidelity of emulation results.\",\n \"Title: Normalization of Application Performance in IEEE 802.11 Networks.\\nYear: 2016\\n\\nAbstract: The IEEE 802.11 standards define a distributed scheme for Wi-Fi access points and stations to fairly share the wireless medium. Even if fully standard-compliant, Wi-Fi devices from different vendors have implementation differences that lead to disparities in their ability to access the medium. Erratic upper-layer behaviors become manifest when devices that exhibit such disparities inter-operate within one network. In this paper we show examples of those behaviors based on common use cases. We find that a primary cause of performance inconsistency for most network applications is the uneven ability of different IEEE 802.11 devices to access the shared medium for transmission of TCP acknowledgments, further aggravated by the excessive size of the buffers where those packets are queued before transmission. We devise and validate in a real network an effective solution for Linux hosts that is based on the link-layer priorities of IEEE 802.11e. This solution allows researchers conducting Wi-Fi experiments to collect device-independent results, and application providers to guarantee a consistent experience to their users across different devices.\",\n \"Title: A variant of environmental adaptation method with real parameter encoding and its application in economic load dispatch problem.\\nYear: 2017\\n\\nAbstract: Environmental Adaptation Method (EAM) and Improved Environmental Adaptation Method (IEAM) were proposed to solve optimization problems with the biological theory of adaptation in mind. Both of these algorithms work with binary encoding, and their performance is comparable with other state-of-art algorithms. To further improve the performance of these algorithms, some major changes are incorporated into the proposed algorithm. The proposed algorithm works with the real value parameter encoding, and, in order to maintain significant convergence rate and diversity, it maintains a balance between exploitation and exploration. The choice to explore or exploit a solution depends on the fitness of the individual. The performance of the proposed algorithm is compared with 17 state-of-art algorithms in 2-D, 3-D, 5-D, 10-D and 20-D dimensions using the COCO (COmparing Continuous Optimisers) framework with Black-Box Optimization Benchmarking (BBOB) functions. It outperforms all other algorithms in 3-D and 5-D, and its performance is comparable to other algorithms for other dimensions. In addition, IEAM-R has been applied to the real world problem of economic load dispatch, and its results demonstrate that it gives minimum fuel cost when compared to other algorithms in different cases.\",\n \"Title: Adaptive 360-Degree Video Streaming using Scalable Video Coding.\\nYear: 2017\\n\\nAbstract: Virtual reality and 360-degree video streaming are growing rapidly, yet, streaming high-quality 360-degree video is still challenging due to high bandwidth requirements. Existing solutions reduce bandwidth consumption by streaming high-quality video only for the user's viewport. However, adding the spatial domain (viewport) to the video adaptation space prevents the existing solutions from buffering future video chunks for a duration longer than the interval that user's viewport is predictable. This makes playback more prone to video freezes due to rebuffering, which severely degrades the user's Quality of Experience especially under challenging network conditions. We propose a new method that alleviates the restrictions on buffer duration by utilizing scalable video coding. Our method significantly reduces the occurrence of rebuffering on links with varying bandwidth without compromising playback quality or bandwidth efficiency compared to the existing solutions. We demonstrate the efficiency of our proposed method using experimental results with real world cellular network bandwidth traces.\",\n \"Title: Layer-Assisted Adaptive Video Streaming.\\nYear: 2018\\n\\nAbstract: HTTP Adaptive Streaming (HAS) is the widely adopted solution for video streaming over the Internet. When network throughput is highly variable, designing an optimal HAS solution that maximizes Quality of Experience (QoE) becomes challenging. Each chunk should be prefetched at highest possible quality while rebufferings and quality switches are minimized. Scalable Video Coding (SVC), with its layered encoding of video, provides more flexibility for HAS clients. It can reduce the occurrence of rebufferings under variable network conditions. However, SVC introduces at least 10% overhead on video bitrate per layer and increases the number of HTTP requests to fetch video chunks. So streaming SVC video at high qualities is more expensive. We propose a solutions that employs both SVC and non-SVC video to improve user's QoE while avoiding the increased bandwidth overhead and HTTP signaling of SVC. Our experiments using real-world bandwidth traces show that this method improves QoE compared to the state-of-the-art adaptation methods under various network conditions.\",\n \"Title: Topological asymptotic analysis of an optimal control problem modeled by a coupled system.\\nYear: 2018\\n\\nAbstract: In this paper, we deal with the topological asymptotic analysis of an optimal control problem modeled by a coupled system. The control is a geometrical object and the cost is given by the misfit between a target function and the state, solution of the Helmholtz-Laplace coupled system. Higher-order topological derivatives are used to devise a non-iterative algorithm to compute the optimal control for the problem of interest. Numerical examples are presented in order to demonstrate the effectiveness of the proposed algorithm.\",\n \"Title: FoV-Aware Edge Caching for Adaptive 360° Video Streaming.\\nYear: 2018\\n\\nAbstract: In recent years, there has been growing popularity of Virtual Reality (VR), enabled by technologies like 360° video streaming. Streaming 360° video is extremely challenging due to high bandwidth and low latency requirements. Some VR solutions employ adaptive 360° video streaming which tries to reduce bandwidth consumption by only streaming high resolution video for user's Field of View (FoV). FoV is the part of the video which is being viewed by the user at any given time. Although FoV-adaptive 360° video streaming has been helpful in reducing bandwidth requirements, streaming 360° video from distant content servers is still challenging due to network latency. Caching popular content close to the end users not only decreases network latency, but also alleviates network bandwidth demands by reducing the number of future requests that have to be sent all the way to remote content servers. In this paper, we propose a novel caching policy based on users' FoV, called FoV-aware caching policy. In FoV-aware caching policy, we learn a probabilistic model of common-FoV for each 360° video based on previous users' viewing histories to improve caching performance. Through experiments with real users' head movement dataset, we show that our proposed approach improves cache hit ratio compared to Least Frequently Used (LFU) and Least Recently Used (LRU) caching policies by at least 40% and 17%, respectively.\",\n \"Title: A Feedback Based Scheme for Improving TCP Performance in Ad-Hoc Wireless Networks\\nYear: 2001\\n\\nAbstract: Ad-hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This frequent topology may lead to sudden packet losses and delays. Transport protocols like TCP have been built mainly for reliable, fixed networks. Hence, when used in ad-hoc networks, TCP misinterprets this loss as congestion and invokes congestion control. This leads to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed, so that the source can distinguish between route failure and network congestion. When a route is disrupted, the source is sent a Route Failure Notification(RFN) packet, allowing it to freeze its timers and stop sending packets. When the route is re-established, the source is informed through a Route Re-establishment Notification (RRN) packet, upon which it resumes by un-freezing timers and continuing packet transmissions. The simulated performance of TCP on ad-hoc networks with and without feedback is compared and reported. It is observed that in the event of route failures, as the route re-establishment time increases, the use of feedback provides significant gains in throughput as well as savings in unnecessary packet transmissions. Several further enhancements and directions for future work are also sketched.\",\n \"Title: A General Analysis Framework for Soft Real-Time Tasks\\nYear: 2019\\n\\nAbstract: Much recent work has been conducted on supporting soft real-time tasks on multiprocessors due to the multicore revolution. While most earlier works focus on the traditional sporadic task model with deterministic worst-case specification, several recent works investigate the stochastic nature of many workloads seen in practice, specifying task execution times using average-case provisioning instead...\",\n \"Title: Dynamic Trajectory Generation and a Robust Controller to Intercept a Moving Ball in a Game Setting\\nYear: 2020\\n\\nAbstract: Complex and interactive robot manipulation skills, such as playing a game of table tennis against a human opponent, are a novel problem with multifaceted challenges. Accurate dynamic trajectory generation in order to respond to the tennis ball from the opponent and a novel control scheme for robust and high-performance tracking of the ball in such dynamic situations is a prerequisite to winning th...\",\n \"Title: End-To-End Real-Time Visual Perception Framework for Construction Automation.\\nYear: 2021\\n\\nAbstract: In this work, we present a robotic solution to automate the task of wall construction. To that end, we present an end-to-end visual perception framework that can quickly detect and localize bricks in a clutter. Further, we present a light computational method of brick pose estimation that incorporates the above information. The proposed detection network predicts a rotated box compared to YOLO and SSD, thereby maximizing the object's region in the predicted box regions. In addition, precision P, recall R, and mean-average-precision (mAP) scores are reported to evaluate the proposed framework. We observed that for our task, the proposed scheme outperforms the upright bounding box detectors. Further, we deploy the proposed visual perception framework on a robotic system endowed with a UR5 robot manipulator and demonstrate that the system can successfully replicate a simplified version of the wall-building task in an autonomous mode.\",\n \"Title: Improving 360-Degree Video Field-of-View Prediction and Edge Caching\\nYear: 2021\\n\\nAbstract: Streaming 360° videos over the Internet to Head Mounted Displays (HMDs) requires high bandwidth owing to their high resolution. Viewers, limited by the Field of View (FoV) of the HMD, can only watch a small portion of the scene at a time. Therefore, predicting the future FoV of viewers and caching popular content in the mobile edge cloud can reduce both downloading latency and traffic over the cor...\",\n \"Title: An approach using heuristic pheromones-based ACO modelling for green vehicle routing optimisation\\nYear: 2022\\n\\nAbstract: A mathematical heuristic-based method was introduced for addressing the issue in green vehicle routing optimisation (GVRO). It analyses a large number of vehicles along with a limited refuelling network. A standard solution to this problem is given in this paper. GVRO seeks to minimise travel time renewable fuel sources while ensuring fewer emissions from greenhouse gases. An effective algorithm relies on a branch/slice optimisation algorithm that combines a variety of valid inequalities in exams to increase lower limits. Implementation of an optimisation algorithm based on heuristic ant colony optimisation (ACO) to obtain the best routes. In addition, the GVRO is better able to handle an accident and eliminates pollution by using the best alternatives.\",\n \"Title: A System-on-Board Integrated Multi-analyte PoC Biosensor for Combined Analysis of Saliva and Exhaled Breath.\\nYear: 2022\\n\\nAbstract: The need for oral health monitoring Point of Care (PoC) systems is ever growing. This is effectively highlighted by the ongoing COVID-19 pandemic where the lack of rapid PoC testing has placed an unsustainable burden on centralized laboratory testing. Urgent development has furthered pathogenic nucleic acid and antibody detection in oral samples throat swabs, but without corresponding advancements in biochemical monitoring through oral biosensing. We have recently reported two novel biosensor technologies for detection of high impact hormones: cortisol in saliva by organic electrolyte gated FETs (OEGFETs), and 8-isoprostane in exhaled breath condensate (EBC) using molecularly imprinted electroimpedance spectroscopy biosensors (MIP EIS). In this work, we report a first stage integration of the two biosensors - previously bench-top proven - with a miniaturized semi-hermetically sealed soft-fluidic enclosure, onto a low-power (<300 mW) customized printed circuit board. Our findings established comparable detection thresholds for the miniaturized board-based configuration and a lab-based test setup, and their ability to characterize, calibrate, and operate these small footprint biosensors. Testing with the 8-isoprostane EBC MIP EIS biosensors showed the system-on-board had an effective frequency range of 100-100kHz, comparable to lab bench impedance analyzers. Despite internal impedance increases of 210%, the expected data features are present in the impedance graphs collected with the PCB. The system-on-board experiments using OEGFET aptasensor showed a predictable behavior and comparable sensor detection range and resolution using unadulterated supernatant and serial dilutions of cortisol over a range of 273 μM to 2.73pM. The portable, multi-analyte oral biosensor is a promising prototype for future packaging and clinical validation.\",\n \"Title: RDQS: A Geospatial Data Analysis System for Improving Roads Directionality Quality\\nYear: 2022\\n\\nAbstract: With the increasing availability of smart devices, billions of users are currently relying on map services for many fundamental daily tasks such as obtaining directions and getting routes. It is becoming more and more important to verify the quality and consistency of route data presented by different map providers. However, verifying this consistency manually is a very time-consuming task. To address this problem, in this paper we introduce a novel geospatial data analysis system that is based on road directionality. We investigate our Road Directionality Quality System (RDQS) using multiple map providers, including: Bing Maps, Google Maps, and OpenStreetMap. Results from the experiments conducted show that our detection neural network is able to detect an arrow's position and direction in map images with >90% F1-Score across each of the different providers. We then utilize this model to analyze map images in six different regions. Our findings show that our approach can reliably assess map quality and discover discrepancies in road directionality across the different providers. We report the percentage of discrepancies found between map providers using this approach in a proposed study area. These results can help determine areas needs to be revised and prioritized to improve the overall quality of the data within maps.\",\n \"Title: A Geospatial Method for Detecting Map-Based Road Segment Discrepancies\\nYear: 2022\\n\\nAbstract: Today, people's lives are enriched by the integration of electronic maps via smartphones. Electronic maps are required for a variety of commercial activities, such as catering, movie viewing, and tourism. Route planning and navigation are particularly intrinsically linked to electronic maps. As a result, it is critical that the roads on the electronic map are complete and accurate. At the present time, there are discrepancies between the map roads of various providers. This paper evaluates the roads on various map providers' maps. Due to the varied terrain depicted on the map, assessing the road properties can be challenging. Additionally, roads of varying thicknesses exist within a tile image, making it difficult to quantify the map's road lengths. This paper proposes a method for extracting road segments using an image binarization technique and employs edge erosion to assist in automatically computing the length of roads within maps. Throughout the paper, we provide comparison and statistical analysis on using our proposed road length detection model across map providers. Results show that our detection model can identify road length accurately and hence provide an overall measure of quality of maps.\",\n \"Title: Maps Vision: A Computer Vision-based System for Detecting Discrepancies in Map Textual Labels\\nYear: 2022\\n\\nAbstract: We demonstrate MapsVision, a computer vision-based framework capable of identifying discrepancies across different map providers for similar geographical locations. In this study, we primarily focus on three map providers including: (a) Bing Maps, (b) Google Maps, and (c) OpenStreetMap. MapsVision detects textual data discrepancies such as: (1) missing location labels (2) misspelled or different keywords, (3) shifted labels, and (4) level of significance manifested by text or label font-size and color. For a given location, our MapsVision framework compares textual labels based on a ground truth entered manually to those that exist in the three map providers. We then use the results of the textual extraction to determine the accuracy of textual data appearing on map providers. Our framework intelligently identifies the set of techniques for each map providers' that can maximize the overall detection accuracy. MapsVision is composed of three main building blocks including: (a) a capturing module that captures map tiles from map providers, (b) an analysis tool that uses computer vision and text-analytic techniques, and (c) a rich visualization interface for displaying statistical and real-time analytics. The objective of MapsVision is to help map editors improve the textual quality of their maps compared to other map providers.\",\n \"Title: PIES-ME '22: 1st Workshop on Photorealistic Image and Environment Synthesis for Multimedia Experiments\\nYear: 2022\\n\\nAbstract: ABSTRACTPhotorealistic media aim to faithfully represent the world, creating an experience that is perceptually indistinguishable from a real world experience. In the past few years, this area has grown significantly, with new multimedia areas emerging, such as light fields, point clouds, ultra-high definition, high frame rate, high dynamic range imaging, and novel 3D audio and sound field technologies. In spite of all the advances done so far, there are several technological challenges to overcome. In particular, research in this field typically requires the use of big datasets, software tools, and powerful infrastructures. Among these, the availability of meaningful datasets, with a diverse and high-quality content, is of significant importance and, to date, most available datasets are limited and do not provide researchers adequate tools to advance the area of photorealistic applications. To help advancing research efforts in this area, this workshop aims to engage experts and researchers on the synthesis of photorealistic images and/or virtual environments, particularly in the form of public datasets, software tools, or infrastructures, for not only multimedia systems research, but also for other fields, such as machine learning, robotics, computer vision, mixed reality, and virtual reality.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":84,"string":"84"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":74,"string":"74"}}},{"rowIdx":75,"cells":{"question_id":{"kind":"string","value":"Xiaoming Wang"},"question":{"kind":"string","value":"Generate an abstract for the title \"Evaluation of Wenchuan earthquake management plan and its effects: A case study on the East Turbine Corporation recovery and reconstruction plan\" using the following items: 1. Scenario-response\n2. Unconventional emergency management\n3. Real-time information\n4. Data mining\n5. Rapid emergency response."},"answer":{"kind":"string","value":"“Scenario-Response” is regarded as the most effective unconventional emergency management method. As unconventional emergency is dynamic event, at different stages for different emergency conditions, a different contingency plan should be applied. In this research, we choice the combination unconventional emergency response program based on real-time information, data mining, forecasting and scenario simulation performance. We also analysis the plan for rapid response of emergency, and evaluate the effectiveness of the emergency program. A case study on the process of The East Turbine Recovery is also presented."},"correct_answer":{"kind":"string","value":"“Scenario-Response” is regarded as the most effective unconventional emergency management method. As unconventional emergency is dynamic event, at different stages for different emergency conditions, a different contingency plan should be applied. In this research, we choice the combination unconventional emergency response program based on real-time information, data mining, forecasting and scenario simulation performance. We also analysis the plan for rapid response of emergency, and evaluate the effectiveness of the emergency program. A case study on the process of The East Turbine Recovery is also presented."},"documents":{"kind":"list like","value":["Title: Robin–Robin domain decomposition methods for the steady-state Stokes–Darcy system with the Beavers–Joseph interface condition\nYear: 2011\n\nAbstract: Domain decomposition methods for solving the coupled Stokes–Darcy system with the Beavers–Joseph interface condition are proposed and analyzed. Robin boundary conditions are used to decouple the Stokes and Darcy parts of the system. Then, parallel and serial domain decomposition methods are constructed based on the two decoupled sub-problems. Convergence of the two methods is demonstrated and the results of computational experiments are presented to illustrate the convergence.","Title: Node Aggregation Degree-Aware Random Routing For Non-Uniform Wireless Sensor Networks\nYear: 2011\n\nAbstract: Routing is still a challenging issue for wireless sensor networks (WSNs), in particular for WSNs with a non-uniform deployment of nodes. This paper introduces a Node Aggregation Degree-aware Random Routing (NADRR) algorithm for non-uniform WSNs with the help of two new concepts, namely the Local Vertical Aggregation Degree (LVAD) and Local Horizontal Aggregation Degree (LHAD). Our basic idea is to first apply the LVAD and LHAD to determine one size-proper forwarding region (rather than a fixed-size one as in uniform node deployment case) for each node participating in routing, then select the next hop node from the size-proper forwarding region in a probabilistic way, considering both the residual energy and distribution of nodes. In this way, a good adaptability to the non-uniform deployment of nodes can be guaranteed by the new routing algorithm. Extensive simulation results show that in comparison with other classical geographic position based routing algorithms, such as GPSR, TPGF and CR, the proposed NADRR algorithm can result in lower node energy consumption, better balance of node energy consumption, higher routing success rate and longer network lifetime.","Title: A Random Key Management Scheme for Wireless Sensor Networks\nYear: 2008\n\nAbstract: The establishment of shared keys between communicating neighbor nodes in wireless sensor networks is a challenge due to resource-constrained sensor networks. Several key pre-distribution schemes have been proposed in literatures to establish pairwise keys between sensor nodes. However, many of them are either too complicated to fit for wireless sensor networks or insecure for some common aggressions. In this paper, we propose a random key management scheme based on random key pre-distribution for wireless sensor networks. To achieve better performance and security, the proposed scheme employs two different phases to establish enhanced pairwise keys between neighboring nodes. Compared with other existing random key pre-distribution schemes, our scheme has better resilience against node capture and also performs better in terms of network connectivity and scalability with appropriate memory, computation and communication overheads.","Title: Access control scheme with tracing for outsourced databases.\nYear: 2012\n\nAbstract: To manage dynamic access control and deter pirate attacks on outsourced databases, a dynamic access control scheme with tracing is proposed. In our scheme, we introduce the traitor tracing idea into outsource databases, and employ a polynomial function and filter function as the basic means of constructing encryption and decryption procedures to reduce computation, communication, and storage overheads. Compared to previous access control schemes for outsourced databases, our scheme can not only protect sensitive data from leaking and perform scalable encryption at the server side without shipping the outsourced data back to the data owner when group membership is changed, but also provide trace-and-revoke features. When malicious users clone and sell their decryption keys for profit, our scheme can trace the decryption keys to the malicious users and revoke them. Furthermore, our scheme avoids massive message exchanges for establishing the decryption key between the data owner and the user. Compared to previously proposed publickey traitor tracing schemes, our scheme can simultaneously achieve full collusion resistance, full recoverability, full revocation, and black-box traceability. The proof of security and analysis of performance show that our scheme is secure and efficient. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.","Title: An intelligent software-integrated environment of IC test\nYear: 1994\n\nAbstract: The migration and simulation of IC test programs among the heterogeneous ATE systems are a very difficult task. An unifying IC test software-integrated environment from simulation to test for digital circuit has been developed. The environment, TeDS which is designed by using object-oriented paradigm, supports two kinds of CAD systems and three kinds of ATE (Automatic Test Equipment). The paper focuses on issues and techniques in developing TeDS based on object-oriented paradigm","Title: On time granularity and event granularity in simulation service composition (WIP)\nYear: 2012\n\nAbstract: There is an increasing need for systematic composition of simulation services in the emerging service-oriented computing environment. An important issue that hinders simulation service composition is the mismatch of granularity when coupling two services together. In this paper, we focus on time granularity and event granularity in composing simulation services at the pragmatic level. We identify and develop four types of granularity handling agents to be associated with the couplings between services. The developed method is illustrated by a coupled weather-wildfire simulation example.","Title: EiSIRS: a formal model to analyze the dynamics of worm propagation in wireless sensor networks\nYear: 2010\n\nAbstract: Based on the epidemic theory, this paper proposes a novel model for analyzing the dynamics of worm propagation in Wireless\n Sensor Networks (WSNs). The proposed model supports the sleep and work interleaving schedule policy for sensor nodes, and\n it can also describe the process of multi-worm propagation in WSNs. In addition, a necessary condition for worms to spread\n in WSNs is derived, which may be useful in designing a secure WSN. Simulation results show that the process of worm propagation\n in WSNs is sensitive to the energy consumption of nodes and the sleep and work interleaving schedule policy for nodes. Therefore,\n this paper provides new insights for the dynamics of worm propagation in WSNs.","Title: Path Reconstruction Based On Natural Language And The Uncertainty Problems\nYear: 2004\n\nAbstract: It is an important research issue to build systems supporting natural language comprehension in social geographic information service. In this paper, representation of a path in natural language (NLRP) is discussed. Based on the syntax model of NLRP, an algorithm named PRA (path reconstruction algorithm) used for generating linear path according to the reference map and NLRP expression is described. Inevitably, a NLRP expression contains some uncertainties, which mainly come from the spatial cognition process and imprecise expression. The uncertainties of NLRP include uncertainties of direction, distance and topologic relationship. They make the NLRP expression ambiguous and bring some problems to PRA. The solution is also discussed.","Title: On Node Isolation Under Churn in Unstructured P2P Networks with Heavy-Tailed Lifetimes\nYear: 2007\n\nAbstract: Previous analytical studies [12], [18] of unstructured P2P resilience have assumed exponential user lifetimes and only considered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-selection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared to uniform selection of neighbors. In fact, the second strategy based on random walks on age-weighted graphs demonstrates that for lifetimes with infinite variance, the system monotonically increases its resilience as its age and size grow. Specifically, we show that the probability of isolation converges to zero as these two metrics tend to infinity. We finish the paper with simulations in finite-size graphs that demonstrate the effect of this result in practice.","Title: Residual-based estimation of peer and link lifetimes in P2P networks\nYear: 2009\n\nAbstract: Existing methods of measuring lifetimes in P2P systems usually rely on the so-called Create-Based Method (CBM), which divides a given observation window into two halves and samples users \"created\" in the first half every Δ time units until they die or the observation period ends. Despite its frequent use, this approach has no rigorous accuracy or overhead analysis in the literature. To shed more light on its performance, we first derive a model for CBM and show that small window size or large Δ may lead to highly inaccurate lifetime distributions. We then show that create-based sampling exhibits an inherent tradeoff between overhead and accuracy, which does not allow any fundamental improvement to the method. Instead, we propose a completely different approach for sampling user dynamics that keeps track of only residual lifetimes of peers and uses a simple renewal-process model to recover the actual lifetimes from the observed residuals. Our analysis indicates that for reasonably large systems, the proposed method can reduce bandwidth consumption by several orders of magnitude compared to prior approaches while simultaneously achieving higher accuracy. We finish the paper by implementing a two-tier Gnutella network crawler equipped with the proposed sampling method and obtain the distribution of ultrapeer lifetimes in a network of 6.4 million users and 60 million links. Our experimental results show that ultrapeer lifetimes are Pareto with shape α ≅ 1.1; however, link lifetimes exhibit much lighter tails with α ≅ 1.8.","Title: Linear combination test for gene set analysis of a continuous phenotype.\nYear: 2013\n\nAbstract: Gene set analysis (GSA) methods test the association of sets of genes with a phenotype in gene expression microarray studies. Many GSA methods have been proposed, especially methods for use with a binary phenotype. Equally, if not more importantly however, is the ability to test the enrichment of a gene signature or pathway against the continuous phenotypes which are routinely and commonly observed in, for example, clinicopathological measurements. It is not always easy or meaningful to dichotomize continuous phenotypes into two classes, and attempting to do this may lead to the inaccurate classification of samples, which would affect the downstream enrichment analysis. In the present study, we have build on recent efforts to incorporate correlation structure within gene sets and pathways into the GSA test statistic. To address the issue of continuous phenotypes directly without the need for artificial discrete classification and thus increase the power of the test while ensuring computational efficiency and rigor, new GSA methods that can incorporate a covariance matrix estimator for a continuous phenotype may present an effective approach.We have designed a new method by extending the GSA approach called Linear Combination Test (LCT) from a binary to a continuous phenotype. Simulation studies and a real microarray dataset were used to compare the proposed LCT for a continuous phenotype, a modification of LCT (referred to as LCT2), and two publicly available GSA methods for continuous phenotypes.We found that the LCT methods performed better than the other two GSA methods; however, this finding should be understood in the context of our specific simulation studies and the real microarray dataset that were used to compare the methods. Free R-codes to perform LCT for binary and continuous phenotypes are available at http://www.ualberta.ca/~yyasui/homepage.html. The R-code to perform LCT for a continuous phenotype is available as Additional file 1.","Title: Ant Colony Optimization-Based Location-Aware Routing for Wireless Sensor Networks\nYear: 2008\n\nAbstract: The routing for Wireless Sensor Networks (WSNs) is a key and hard problem, and it is a research topic in the field of WSN applications. Based on Ant Colony Optimization (ACO), this paper proposes a novel adaptive intelligent routing scheme for WSNs. Following the proposed scheme, a high performance routing algorithm for WSNs is designed. The proposed routing scheme is very different from the existing ACO based routing schema for WSNs. On one hand, in the proposed scheme, the search range for an ant to select its next-hop node is limited to a subset of the set of the neighbors of the current node. On the other hand, by fusing the residual energy and the global and local location information of nodes, the new probability transition rules for an ant to select its next-hop node are defined. Compared with other ACO based routing algorithms for WSNs, the proposed routing algorithm has a better network performance on aspects of energy consumption, energy efficiency, and packet delivery latency.","Title: Efficient and Long-Time Accurate Second-Order Methods for the Stokes-Darcy System.\nYear: 2013\n\nAbstract: We propose and study two second-order in time implicit-explicit methods for the coupled Stokes-Darcy system that governs flows in karst aquifers and other subsurface flow systems. The first method is a combination of a second-order backward differentiation formula and the second-order Gear's extrapolation approach. The second is a combination of the second-order Adams-Moulton and second-order Adams-Bashforth methods. Both algorithms only require the solution of decoupled Stokes and Darcy problems at each time-step. Hence, these schemes are very efficient and can be easily implemented using legacy codes. We establish the unconditional and uniform in time stability for both schemes. The uniform in time stability leads to uniform in time control of the error which is highly desirable for modeling physical processes, e.g., contaminant sequestration and release, that occur over very long time scales. Error estimates for fully discretized schemes using finite element spatial discretizations are derived. Numerical examples are provided that illustrate the accuracy, efficiency, and long-time stability of the two schemes.","Title: Threshold Proxy Signature Scheme with Strong Real-Time Efficiency\nYear: 2008\n\nAbstract: The threshold proxy signature scheme with strong real-time efficiency is proposed based on a trapdoor hash function and the sharing secret technology. In the scheme, the procedure of generating threshold proxy signature is performed in two phases. The off-line phase generates a threshold proxy pre-signature before the message to be signed is even known. The pre-signature is independent of the particular message to be signed and is stored for future in the on-line phase. While on-line phase generates quickly a threshold proxy signature using the pre-signature once the message to be signed is presented. The on-line phase is typically very fast and strong real-time efficiency since it only needs a few modular additions and multiplications and one round of communication among proxy signers. Furthermore, the scheme not only has strong real-time efficiency, but also withstands the conspiracy attack existed in the previous schemes and requires no trusted third party. The scheme is particularly useful for requiring the strong real-time efficiency and fully distributed networks such as electric wallet or smart cards etc.","Title: Construction of Anti-Collusion Codes Based on Cover-Free Families\nYear: 2009\n\nAbstract: Digital fingerprinting is a technique for identifying users who use multimedia content for unintended purpose, such as redistribution. In order to characterize the fingerprints that can withstand collusion attack, Dittmann et. al proposed the definition of anti-collusion codes (ACCs). In this paper, we present a new approach to construct anti-collusion codes based on cover-free families. All the previous constructions of ACCs are special cases of our construction. Especially, we can construct ACCs by using error-correcting codes. Collusion resistance comparison of different schemes show that our scheme is more efficient than previous ACCs. Some related problems on this subject are proposed.","Title: Translational integrity and continuity: personalized biomedical data integration.\nYear: 2009\n\nAbstract: Translational research data are generated in multiple research domains from the bedside to experimental laboratories. These data are typically stored in heterogeneous databases, held by segregated research domains, and described with inconsistent terminologies. Such inconsistency and fragmentation of data significantly impedes the efficiency of tracking and analyzing human-centered records. To address this problem, we have developed a data repository and management system named TraM (http://tram.uchicago.edu), based on a domain ontology integrated entity relationship model. The TraM system has the flexibility to recruit dynamically evolving domain concepts and the ability to support data integration for a broad range of translational research. The web-based application interfaces of TraM allow curators to improve data quality and provide robust and user-friendly cross-domain query functions. In its current stage, TraM relies on a semi-automated mechanism to standardize and restructure source data for data integration and thus does not support real-time data application.","Title: Research on Simulation of Temperature Control System for Gyro Based on Single Neuron PID\nYear: 2010\n\nAbstract: In the inertial navigation system, the performance of temperature control system for gyro directly impacts on the precision and property of the inertial navigation system. The traditional control algorithm is simple, but it takes a longer time to settle the system, and the effect is not ideal. This paper presents an algorithm based on single neuron adaptive PID control, which takes advantage of self-learning, self-adaptation ability of a single neuron, can adjust the corresponding proportion, integral, differential coefficient, and achieve the rapid real-time on-line control to the temperature control system. The simulation results show that the method is efficient, because of a short period of time and small overshoot.","Title: Spreading speeds and travelling waves for non-monotone time-delayed 2D lattice systems.\nYear: 2013\n\nAbstract: In this paper, a non-monotone time delayed 2D lattice system with global interaction is studied. The important feature of the model is the reflection of the joint effect of the diffusion dynamics, the nonlocal delayed effect and the direction of propagation. The existence of travelling waves for the wave speed c≥c∗(θ) is established by Schauder’s fixed point theorem and a limiting argument, where θ is any fixed direction of propagation. The spreading speed is investigated by comparison arguments and a fluctuation method. It is also shown that the spreading speed coincides with the minimal wave speed along every direction. Particularly, letting the direction of propagation θ=0 or π2, the wave profile equation of the 2D lattice system can reduce to the wave profile equation of 1D lattice system and therefore, our results can cover the previous works.","Title: Facilitating pharmacogenetic studies using electronic health records and natural-language processing: a case study of warfarin.\nYear: 2011\n\nAbstract: Objective DNA biobanks linked to comprehensive electronic health records systems are potentially powerful resources for pharmacogenetic studies. This study sought to develop natural-language-processing algorithms to extract drug-dose information from clinical text, and to assess the capabilities of such tools to automate the data-extraction process for pharmacogenetic studies. Materials and methods A manually validated warfarin pharmacogenetic study identified a cohort of 1125 patients with a stable warfarin dose, in which 776 patients were managed by Coumadin Clinic physicians, and the remaining 349 patients were managed by their providers. The authors developed two algorithms to extract weekly warfarin doses from both data sets: a regular expression-based program for semistructured Coumadin Clinic notes; and an advanced weekly dose calculator based on an existing medication information extraction system (Med Ex) for narrative providers' notes. The authors then conducted an association analysis between an automatically extracted stable weekly dose of warfarin and four genetic variants of VKORC1 and CYP2C9 genes. The performance of the weekly dose-extraction program was evaluated by comparing it with a gold standard containing manually curated weekly doses. Precision, recall, F-measure, and overall accuracy were reported. Associations between known variants in VKORC1 and CYP2C9 and warfarin stable weekly dose were performed with linear regression adjusted for age, gender, and body mass index. Results The authors' evaluation showed that the Med Ex-based system could determine patients' warfarin weekly doses with 99.7% recall, 90.8% precision, and 93.8% accuracy. Using the automatically extracted weekly doses of warfarin, the authors successfully replicated the previous known associations between warfarin stable dose and genetic variants in VKORC1 and CYP2C9.","Title: Finite Element Approximations for Stokes-Darcy Flow with Beavers-Joseph Interface Conditions\nYear: 2010\n\nAbstract: Numerical solutions using finite element methods are considered for transient flow in a porous medium coupled to free flow in embedded conduits. Such situations arise, for example, for groundwater flows in karst aquifers. The coupled flow is modeled by the Darcy equation in a porous medium and the Stokes equations in the conduit domain. On the interface between the matrix and conduit, Beavers-Joseph interface conditions, instead of the simplified Beavers-Joseph-Saffman conditions, are imposed. Convergence and error estimates for finite element approximations are obtained. Numerical experiments illustrate the validity of the theoretical results.","Title: IRLbot: scaling to 6 billion pages and beyond\nYear: 2009\n\nAbstract: Abstract—This paper,shares,our,experience,in designing,a web,crawler that can download,billions of pages using a single- server implementation,and,models,its performance.,We,show that with,the quadratically,increasing,complexity,of verifying URL uniqueness, BFS crawl order, and fixed per-host rate- limiting, current crawling algorithms cannot effectively cope with the sheer volume of URLs generated in large crawls, highly-branching spam, legitimate multi-million-page blog sites, and,infinite loops created,by server-side scripts. We,offer a set of techniques,for dealing,with,these issues and,test their performance,in an implementation,we call IRLbot. In our recent experiment that lasted 41 days, IRLbot running on a single server successfully crawled,6:3 billion valid HTML pages,(7:6 billion connection,requests) and,sustained,an average,download,rate of 319 mb/s (1;789 pages/s). Unlike our prior experiments,with algorithms proposed in related work, this version of IRLbot did not experience any,bottlenecks and,successfully handled,content from over 117 million hosts, parsed out 394 billion links, and discovered,a subset,of the web,graph,with 41 billion unique nodes.","Title: Real time clustering of sensory data in wireless sensor networks\nYear: 2009\n\nAbstract: Data mining in wireless sensor networks (WSNs) is a new emerging research area. This paper investigates the problem of real time clustering of sensory data in WSNs. The objective is to cluster the data collected by sensor nodes in real time according to data similarity in a d-dimensional sensory data space. To perform in-network data clustering efficiently, a Hilbert Curves based mapping algorithm, HilbertMap, is proposed to convert a d-dimensional sensory data space into a two-dimensional area covered by a sensor network. Based on this mapping, a distributed algorithm for clustering sensory data, H-Cluster, is proposed. It guarantees that the communications for sensory data clustering mostly occur among geographically nearby sensor nodes and sensory data clustering is accomplished in in-network manner. Extensive simulation experiments were conducted using both real-world datasets and synthetic datasets to evaluate the algorithms. H-Cluster consistently achieves the lowest data loss rate, the highest energy efficiency, and the best clustering quality.","Title: Modeling Heterogeneous User Churn and Local Resilience of Unstructured P2P Networks\nYear: 2006\n\nAbstract: We present the design of a Network Forensic Alliance (NFA), to allow multiple administrative domains (ADs) to jointly locatethe origin of epidemic spreading attacks. ADs in the NFA collaborate in a distributed protocol for post-mortem analysis ofworm-like ...","Title: Variable selection via combined penalization for high-dimensional data analysis\nYear: 2010\n\nAbstract: We propose a new penalized least squares approach to handling high-dimensional statistical analysis problems. Our proposed procedure can outperform the SCAD penalty technique (Fan and Li, 2001) when the number of predictors p is much larger than the number of observations n, and/or when the correlation among predictors is high. The proposed procedure has some of the properties of the smoothly clipped absolute deviation (SCAD) penalty method, including sparsity and continuity, and is asymptotically equivalent to an oracle estimator. We show how the approach can be used to analyze high-dimensional data, e.g., microarray data, to construct a classification rule and at the same time automatically select significant genes. A simulation study and real data examples demonstrate the practical aspects of the new method.","Title: Understanding and modeling the internet topology: economics and evolution perspective\nYear: 2010\n\nAbstract: In this paper, we seek to understand the intrinsic reasons for the well-known phenomenon of heavy-tailed degree in the Internet AS graph and argue that in contrast to traditional models based on preferential attachment and centralized optimization, the Pareto degree of the Internet can be explained by the evolution of wealth associated with each ISP. The proposed topology model utilizes a simple multiplicative stochastic process that determines each ISP's wealth at different points in time and several \"maintenance\" rules that keep the degree of each node proportional to its wealth. Actual link formation is determined in a decentralized fashion based on random walks, where each ISP individually decides when and how to increase its degree. Simulations show that the proposed model, which we call Wealth-based Internet Topology (WIT), produces scale-free random graphs with tunable exponent α and high clustering coefficients (between 0.35 and 0.5) that stay invariant as the size of the graph increases. This evolution closely mimics that of the Internet observed since 1997.","Title: A Spatial-temporal Model for the Malware Propagation in MWSNs Based on the Reaction-Diffusion Equations.\nYear: 2012\n\nAbstract: Mobile wireless sensor networks (MWSNs) have important applications in many fields. However, MWSNs are becoming attacked targets due to its large-scale applications. The focus of this work is to develop a modeling framework and mathematical model for characterizing the process of malware propagation in MWSNs from two aspects of time and space. It is important to understand malware's potential damages, and to develop counter-measures. Firstly, we develop a formal model for describing the process of malware propagation in MWSNs based on the reaction-diffusion equations. Then, we derive the threshold for predicting whether a malware propagates or not in MWSNs as time passes. Finally, we propose the spatial pattern based method to analyze and predict the spatial distribution of nodes infected by malwares as time passes. Both theoretical analysis and extensive simulation results show that the movement speed of nodes and the communication radius of nodes have a significant effect on the malware propagation in MWSNs. © 2012 Springer-Verlag.","Title: Approximation of stationary statistical properties of dissipative dynamical systems: Time discretization\nYear: 2010\n\nAbstract: We consider temporal approximation of stationary statistical properties of dissipative infinite-dimensional dynamical systems. We demonstrate that stationary statistical properties of the time discrete approximations, i.e., numerical scheme, converge to those of the underlying continuous dissipative infinite-dimensional dynamical system under three very natural assumptions as the time step approaches zero. The three conditions that are sufficient for the convergence of the stationary statistical properties are: (1) uniform dissipativity of the scheme in the sense that the union of the global attractors for the numerical approximations is pre-compact in the phase space; (2) convergence of the solutions of the numerical scheme to the solution of the continuous system on the unit time interval [0, 1] uniformly with respect to initial data from the union of the global attractors; (3) uniform continuity of the solutions to the continuous dynamical system on the unit time interval [0, 1] uniformly for initial data from the union of the global attractors. The convergence of the global attractors is established under weaker assumptions. An application to the infinite Prandtl number model for convection is discussed.","Title: Adaptive energy and location aware routing in wireless sensor network\nYear: 2010\n\nAbstract: This paper proposes a novel routing algorithm called AELAR for wireless sensor networks to meet QoS requirements: energy conservation and data delay reduction. Firstly, we propose a novel method of dividing routing request zone and construct a select equation which can enlarge the energy awareness as network time goes on. We make the routing request zone and factors in select equation changed automatically. Simulation results show that AELAR outperforms traditional algorithms in the performance of network lifetime, utilization and consumption balancing of energy and data delay.","Title: On zone-balancing of peer-to-peer networks: analysis of random node join\nYear: 2004\n\nAbstract: Balancing peer-to-peer graphs, including zone-size distributions, has recently become an important topic of peer-to-peer (P2P) research [1], [2], [6], [19], [31], [36]. To bring analytical understanding into the various peer-join mechanisms, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic results for the maximum and minimum zone sizes that hold with high probability.","Title: Long-time behavior for the Hele-Shaw-Cahn-Hilliard system.\nYear: 2012\n\nAbstract: We study the Hele-Shaw-Cahn-Hilliard system that models two phase incompressible Darcian flow in porous media with matched density but arbitrary viscosity contrast. In the 3D case, we prove eventual regularity of weak solutions, as well as existence of global classical solutions if either the Peclet number is sufficiently small or the initial datum is close to one local energy minimizer of the free energy. In both 2D and 3D, we demonstrate that the.-limit set of each trajectory consists of a single steady state. Finally, stability of local minimizers is established.","Title: On internal cardinal direction relations\nYear: 2005\n\nAbstract: Internal Cardinal Direction (ICD) relations can be considered as the refinement to the contains/within topological relation. It is widely used to describe the position of an object in a region. In this paper, three ICD models with varying degrees of details are presented – ICD-5, ICD-9 and ICD-13. In each of these, the notion of a “middle part” is defined using Minimum Bounding Rectangles (MBR). Then focusing on ICD-9, three representation methods are discussed. They are major portion, point set of intersections and proportions of intersections respectively. The ICD-9 model is validated by a cognitive experiment, which helped to determine the size of the middle part in ICD-9 and validate the MBR-based partition method. Based on a psychological theory about vague predicates, conceptual neighborhood and intersection of ICD relations are also discussed briefly.","Title: An efficient second order in time scheme for approximating long time statistical properties of the two dimensional Navier–Stokes equations\nYear: 2012\n\nAbstract: We investigate the long time behavior of the following efficient second-order in time scheme for the 2D Navier–Stokes equations in a periodic box: $$\\begin{array}{ll}{\\frac{3\\omega^{n+1} - 4\\omega^n + \\omega^{n-1}}{2k} + \\nabla^\\perp(2\\psi^n - \\psi^{n-1}) \\cdot \\nabla(2\\omega^n - \\omega^{n-1})- \\nu\\Delta\\omega^{n+1} = f^{n+1},} \\\\ {\\quad -{\\Delta} {\\psi}^{n} = {\\omega}^{n}.}\\end{array}$$ The scheme is a combination of a 2nd-order in time backward-differentiation and a particular explicit Adams–Bashforth treatment of the advection term. Therefore only a linear constant coefficient Poisson solver is needed at each time step. We prove uniform in time bounds on this scheme in $${{\\dot{L}^2,\\, \\dot{H}^1_{per}}}$$ and $${{\\dot{H}^2_{per}}}$$ provided that the time-step is sufficiently small. These time uniform estimates further lead to the convergence of long time statistics (stationary statistical properties) of the scheme to that of the NSE itself at vanishing time-step.","Title: Load-balancing performance of consistent hashing: asymptotic analysis of random node join\nYear: 2007\n\nAbstract: Balancing of structured peer-to-peer graphs, including their zone sizes, has recently become an important topic of distributed hash table (DHT) research. To bring analytical understanding into the various peer-join mechanisms based on consistent hashing, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic bounds for the maximum and minimum zone sizes that hold with high probability. Several of our results contradict those of prior work and shed new light on the theoretical performance limitations of consistent hashing. We use simulations to verify our models and compare the performance of the various methods using the example of recently proposed de Bruijn DHTs.","Title: p-Percent Coverage Schedule in Wireless Sensor Networks\nYear: 2008\n\nAbstract: We investigate the p-percent coverage problem in this paper and propose two algorithms to prolong network lifetime based on the fact that for some applications full coverage is not necessary and different subareas of the monitored area may have different coverage requirements. The first algorithm, CPCA, is a centralized algorithm which selects the least number of nodes to monitor p-percent of the monitored area. The second algorithm, DPCP, is a distributed algorithm which can determine a set of nodes in a distributed manner to cover p-percent of the monitored area. Both of the algorithms guarantee network connectivity. The simulation results show that our algorithms can remarkably prolong network lifetime, have less than 5% unrequired coverage for large networks and employ nodes fairly for most cases.","Title: Modeling Residual-Geometric Flow Sampling\nYear: 2011\n\nAbstract: Traffic monitoring and estimation of flow parameters in high-speed routers have recently become challenging as the Internet grew in both scale and complexity. In this paper, we focus on a family of flow-size estimation algorithms we call Residual-Geometric Sampling (RGS), which generates a random point within each flow according to a geometric random variable and records all remaining packets in a flow counter. Our analytical investigation shows that previous estimation algorithms based on this method exhibit bias in recovering flow statistics from the sampled measurements. To address this problem, we derive a novel set of unbiased estimators for RGS, validate them using real Internet traces, and show that they provide an accurate and scalable solution to Internet traffic monitoring.","Title: An approach for selecting seed URLs of focused crawler based on user-interest ontology.\nYear: 2014\n\nAbstract: Seed URLs selection for focused Web crawler intends to guide related and valuable information that meets a user's personal information requirement and provide more effective information retrieval. In this paper, we propose a seed URLs selection approach based on user-interest ontology. In order to enrich semantic query, we first intend to apply Formal Concept Analysis to construct user-interest concept lattice with user log profile. By using concept lattice merger, we construct the user-interest ontology which can describe the implicit concepts and relationships between them more appropriately for semantic representation and query match. On the other hand, we make full use of the user-interest ontology for extracting the user interest topic area and expanding user queries to receive the most related pages as seed URLs, which is an entrance of the focused crawler. In particular, we focus on how to refine the user topic area using the bipartite directed graph. The experiment proves that the user-interest ontology can be achieved effectively by merging concept lattices and that our proposed approach can select high quality seed URLs collection and improve the average precision of focused Web crawler.","Title: An Optimal Algorithm for Minimizing Cluster Overlap of ACE\nYear: 2008\n\nAbstract: In order to reduce channel contention, support scalability and prolong the lifetime of the sensor networks, sensor nodes are often grouped into clusters. Algorithm for Cluster Establishment (ACE) is a clustering algorithm for sensor networks that uses three rounds of feedback to induce the formation of a highly efficient cover of uniform clusters over the network. In this paper, we present an optimizing algorithm for minimizing the cluster overlap of ACE. Simulation shows the proposed algorithm can efficiently eliminate the redundant cluster heads and minimize the cluster overlap.","Title: Second-order Convex Splitting Schemes for Gradient Flows with Ehrlich-Schwoebel Type Energy: Application to Thin Film Epitaxy\nYear: 2012\n\nAbstract: We construct unconditionally stable, unconditionally uniquely solvable, and second-order accurate (in time) schemes for gradient flows with energy of the form $\\int_\\Omega ( F(\\nabla\\phi({\\bf x})) + \\frac{\\epsilon^2}{2}|\\Delta\\phi({\\bf x})|^2 ) d{\\bf x}$. The construction of the schemes involves the appropriate combination and extension of two classical ideas: (i) appropriate convex-concave decomposition of the energy functional and (ii) the secant method. As an application, we derive schemes for epitaxial growth models with slope selection ($F({\\bf y})= \\frac14(|{\\bf y}|^2-1)^2$) or without slope selection ($F({\\bf y})=-\\frac12\\ln(1+|{\\bf y}|^2)$). Two types of unconditionally stable uniquely solvable second-order schemes are presented. The first type inherits the variational structure of the original continuous-in-time gradient flow, while the second type does not preserve the variational structure. We present numerical simulations for the case with slope selection which verify well-known physical scaling laws for the long time coarsening process.","Title: Fuzzy random multi-objective optimization based routing for wireless sensor networks\nYear: 2014\n\nAbstract: Wireless sensor networks are deployed in complex and uncertain environments, and multiple objectives of routing algorithms are expected to be optimal. However, routing algorithms based on deterministic single objective optimization may not flexibly meet the above needs of applications. This paper adopts fuzzy random optimization and multi-objective optimization, introduces fuzzy random variables to describe both fuzziness and randomness of link delay, link reliability and nodes' residual energy, and proposes a routing model based on fuzzy random expected value and standard deviation model. A hybrid routing algorithm based on fuzzy random multi-objective optimization is designed, which embeds fuzzy random simulation into genetic algorithm with Pareto optimal solution. Simulation results show that the presented algorithm, by adjusting the parameters of fuzzy random variables for depicting both fuzziness and randomness, achieves a longer lifetime and wider performances of delay, latency jitter, reliability, communication interference, energy and balanced energy distribution. Therefore, the presented algorithm can meet different application needs of the cluster head network in the two-tiered wireless sensor networks.","Title: A novel privacy and copyright protection enforced peer-to-peer network\nYear: 2005\n\nAbstract: Peer-to-peer (P2P) networks are widely used to share copyrighted contents and software illegally around the world. Development and applications of P2P technologies have faced strong legal and legislative challenges. A P2P network has to have built-in copyright protection to enable P2P technologies to advance on its own without court's and legislature's interference. In this paper, we propose a novel and practical P2P network with a strong privacy protection and reliable tracking mechanism to track the original uploader of any material in the P2P network. When a pirated material is found, its uploader is tracked down, and can be punished by revoking the access to the network, removing his or her uploaded materials, etc. The whole protection system is completely transparent to end users. The proposed scheme would effectively deter users from uploading illegally any copyrighted materials to and dramatically reduce copyrighted materials shared through our P2P network.","Title: Fuzzy colored time Petri net and termination analysis for fuzzy Event-Condition-Action rules\nYear: 2013\n\nAbstract: Knowledge systems are characterized by being active, uncertain and adaptive in pervasive computing environments, and Fuzzy Event-Condition-Action (ECA) rules can effectively describe these features of knowledge systems. To analyze the static structure and dynamic behavior of fuzzy ECA rules, a fuzzy colored time Petri net model (FCTPN) is proposed. The FCTPN is able to model the fuzzy ECA rules with characteristics such as fuzzy composite events, fuzzy composite conditions, event consumption modes and rule coupling modes. Based on the FCTPN, termination analysis of fuzzy ECA rules is examined, and an efficient termination analysis algorithm is proposed with consideration of all the characteristics of fuzzy ECA rules. Compared with existing termination analysis algorithms of ECA rules, the proposed algorithm has higher accuracy and lower time complexity, and thus it is more suitable for pervasive computing environments.","Title: On minimum class locality preserving variance support vector machine\nYear: 2010\n\nAbstract: In this paper, a so-called minimum class locality preserving variance support machine (MCLPV_SVM) algorithm is presented by introducing the basic idea of the locality preserving projections (LPP), which can be seen as a modified class of support machine (SVM) and/or minimum class variance support machine (MCVSVM). MCLPV_SVM, in contrast to SVM and MCVSVM, takes the intrinsic manifold structure of the data space into full consideration and inherits the characteristics of SVM and MCVSVM. We discuss in the paper the linear case, the small sample size case and the nonlinear case of the MCLPV_SVM. Similar to MCVSVM, the MCLPV_SVM optimization problem in the small sample size case is solved by using dimensionality reduction through principal component analysis (PCA) and one in the nonlinear case is transformed into an equivalent linear MCLPV_SVM problem under kernel PCA (KPCA). Experimental results on real datasets indicate the effectiveness of the MCLPV_SVM by comparing it with SVM and MCVSVM.","Title: Using virtual ATE model to migrate test programs\nYear: 1995\n\nAbstract: Because of high development costs of IC (Integrated Circuit) test programs, recycling existing test programs from one kind\n of ATE (Automatic Test Equipment) to another or generating directly from CAD simulation modules to ATE is more and more valuable.\n In this paper, a new approach to migrating test programs is presented. A virtual ATE model based on object-oriented paradigm\n is developed; it runs Test C++ (an intermediate test control language) programs and TeIF (Test Intermediate Format—an intermediate\n pattern), migrates test programs among three kinds of ATE (Ando DIC8032, Schlumberger S15 and GenRad 1732) and generates test\n patterns from two kinds of CAD (Daisy and Panda) automatically.","Title: A level-set based variational method for design and optimization of heterogeneous objects\nYear: 2005\n\nAbstract: A heterogeneous object is referred to as a solid object made of different constituent materials. The object is of a finite collection of regions of a set of prescribed material classes of continuously varying material properties. These properties have a discontinuous change across the interface of the material regions. In this paper, we propose a level-set based variational approach for the design of this class of heterogeneous objects. Central to the approach is a variational framework for a well-posed formulation of the design problem. In particular, we adapt the Mumford–Shah model which specifies that any point of the object belongs to either of two types: inside a material region of a well-defined gradient or on the boundary edges and surfaces of discontinuities. Furthermore, the set of discontinuities is represented implicitly, using a multi-phase level set model. This level-set based variational approach yields a computational system of coupled geometric evolution and diffusion partial differential equations. Promising features of the proposed method include strong regularity in the problem formulation and inherent capabilities of geometric and material modeling, yielding a common framework for optimization of the heterogeneous objects that incorporates dimension, shape, topology, and material properties. The proposed method is illustrated with several 2D examples of optimal design of multi-material structures and materials.","Title: The Development of E-Commerce under the Influence of China Mobile Communications\nYear: 2010\n\nAbstract: The development of E-Commerce under the influence of China Mobile Communications","Title: Node isolation model and age-based neighbor selection in unstructured P2P networks\nYear: 2009\n\nAbstract: Previous analytical studies of unstructured P2P resilience have assumed exponential user lifetimes and only con-sidered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-se-lection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared with uniform selection of neighbors. In fact, the second strategy based on random walks on age-proportional graphs demonstrates that, for lifetimes with infinite variance, the system monotonically increases its resilience as its age and size grow. Specifically, we show that the probability of isolation converges to zero as these two metrics tend to infinity. We finish the paper with simulations in finite-size graphs that demonstrate the effect of this result in practice.","Title: Study on Embedded System Grid\nYear: 2005\n\nAbstract: The center of gravity of the computer industry is now moving from personal computing into embedded computing. At present, the key to realize intellectual control and network control of manufacturing equipments is to embed the embedded system into manufacturing equipment and extend the control method of manufacturing equipments to the remote network through the network function of the embedded system. In this paper, the characteristic of embedded system and the architecture of embedded system grid are introduced firsty. Then, the interface method between embedded system and grid are discussed. The control model of embedded system resources under the grid environment, the method of overall sharing embedded system and its equipment are also describled. After that, the embedded system grid technology of sharing and controlling embedded resources are presented.","Title: An Adaptive State Detection Service for Manufacturing Grid.\nYear: 2007\n\nAbstract: Manufacturing grid serves as a distributed platform for integrating manufacturing resources and offering shared service. The state knowledge of the manufacturing resources is recorded efficiently. Thus resource exceptions can be timely noticed and removed to ensure reliable service. Given the features of manufacturing grid and the strategy of failure detector in the mode of PULL, this paper proposes a new mode of state detection algorithm for manufacturing grid. This algorithm is capable of meeting various demands of all kinds of manufacturing resources, and supporting the strategy of scheduling priority of local resources demanding no clock synchronization. Data from a manufacturing grid test bed shows that the algorithm can accurately and dynamically record the resource state, and it can meet the demands of resource detection in the manufacturing grid.","Title: Robust lifetime measurement in large-scale P2P systems with non-stationary arrivals\nYear: 2009\n\nAbstract: Characterizing user churn has become an important topic in studying P2P networks, both in theoretical analysis and system design. Recent work has shown that direct sampling of user lifetimes may lead to certain bias (arising from missed peers and round-off inconsistencies) and proposed a technique that estimates lifetimes based on sampled residuals. In this paper, however, we show that under non-stationary arrivals, which are often present in real systems, residual-based sampling does not correctly reconstruct user lifetimes and suffers a varying degree of bias, which in some cases makes estimation completely impossible. We overcome this problem using two contributions: a novel non-stationary ON/OFF churn model and an unbiased randomized residual sampling technique for measuring user lifetimes. The former allows correlation between ON/OFF periods of the same user and exhibits different join rates during the day. The latter spreads sampling points uniformly during the day and uses a novel estimator to reconstruct the underlying lifetime distribution. We finish the paper with experimental measurements of Gnutella and discussing reduction in overhead compared to direct sampling methods.","Title: Analysis of Nonlinear Spectral Eddy-Viscosity Models of Turbulence\nYear: 2010\n\nAbstract: Fluid turbulence is commonly modeled by the Navier-Stokes equations with a large Reynolds number. However, direct numerical simulations are not possible in practice, so that turbulence modeling is introduced. We study artificial spectral viscosity models that render the simulation of turbulence tractable. We show that the models are well posed and have solutions that converge, in certain parameter limits, to solutions of the Navier-Stokes equations. We also show, using the mathematical analyses, how effective choices for the parameters appearing in the models can be made. Finally, we consider temporal discretizations of the models and investigate their stability.","Title: A Linear Iteration Algorithm for a Second-Order Energy Stable Scheme for a Thin Film Model Without Slope Selection\nYear: 2014\n\nAbstract: We present a linear iteration algorithm to implement a second-order energy stable numerical scheme for a model of epitaxial thin film growth without slope selection. The PDE, which is a nonlinear, fourth-order parabolic equation, is the $$L^2$$ L 2 gradient flow of the energy $$ \\int _\\Omega \\left( - \\frac{1}{2} \\ln \\left( 1 + | \\nabla \\phi |^2 \\right) + \\frac{\\epsilon ^2}{2}|\\Delta \\phi (\\mathbf{x})|^2 \\right) \\mathrm{d}\\mathbf{x}$$ 驴 Ω - 1 2 ln 1 + | 驴 驴 | 2 + ∈ 2 2 | Δ 驴 ( x ) | 2 d x . The energy stability is preserved by a careful choice of the second-order temporal approximation for the nonlinear term, as reported in recent work (Shen et al. in SIAM J Numer Anal 50:105---125, 2012). The resulting scheme is highly nonlinear, and its implementation is non-trivial. In this paper, we propose a linear iteration algorithm to solve the resulting nonlinear system. To accomplish this we introduce an $$O(s^2)$$ O ( s 2 ) (with $$s$$ s the time step size) artificial diffusion term, a Douglas-Dupont-type regularization, that leads to a contraction mapping property. As a result, the highly nonlinear system can be decomposed as an iteration of purely linear solvers, which can be very efficiently implemented with the help of FFT in a collocation Fourier spectral setting. We present a careful analysis showing convergence for the numerical scheme in a discrete $$L^\\infty (0, T; H^1) \\cap L^2 (0,T; H^3)$$ L 驴 ( 0 , T ; H 1 ) 驴 L 2 ( 0 , T ; H 3 ) norm. Some numerical simulation results are presented to demonstrate the efficiency of the linear iteration solver and the convergence of the scheme as a whole.","Title: Modeling the Evolution of Degree Correlation in Scale-Free Topology Generators\nYear: 2008\n\nAbstract: In this paper, we examine the asymptotic behavior of degree correlation (i.e., the joint degree distribution of adjacent nodes) in several scale-free topology generators GED [13], PLRG [1], GLP [10], BA [3], AB [2]. We present a unifying analytical framework that allows tractable analysis of degree correlation in all studied models and derive asymptotic formulas of two degree correlation metrics - assortativity and clustering. Our results indicate that all studied generators become uncorrelated as graph size increases, which is inconsistent with time-invariance of these metrics in real networks such as the Internet [36], [48], [50]. Since the class of degree-based generators is incapable of reproducing evolving characteristics of the Internet, we study three other models that evolve graphs using different rules than preference of degree (e.g., based on random walks [50], optimization [17], and geometry [23]) and show using simulations that these models are much more viable alternatives for replicating the complex structure of Internet-like graphs.","Title: A Parallel Robin-Robin Domain Decomposition Method for the Stokes-Darcy System\nYear: 2011\n\nAbstract: We propose a new parallel Robin-Robin domain decomposition method for the coupled Stokes-Darcy system with Beavers-Joseph-Saffman-Jones interface boundary condition. In particular, we prove that, with an appropriate choice of parameters, the scheme converges geometrically independent of the mesh size.","Title: Residual-Based Measurement of Peer and Link Lifetimes in Gnutella Networks\nYear: 2007\n\nAbstract: Existing methods of measuring lifetimes in P2P systems usually rely on the so-called create-based method (CBM), which divides a given observation window into two halves and samples users \"created\" in the first half every Delta time units until they die or the observation period ends. Despite its frequent use, this approach has no rigorous accuracy or overhead analysis in the literature. To shed more light on its performance, we flrst derive a model for CBM and show that small window size or large Delta may lead to highly inaccurate lifetime distributions. We then show that create-based sampling exhibits an inherent tradeoff between overhead and accuracy, which does not allow any fundamental improvement to the method. Instead, we propose a completely different approach for sampling user dynamics that keeps track of only residual lifetimes of peers and uses a simple renewal-process model to recover the actual lifetimes from the observed residuals. Our analysis indicates that for reasonably large systems, the proposed method can reduce bandwidth consumption by several orders of magnitude compared to prior approaches while simultaneously achieving higher accuracy. We finish the paper by implementing a two-tier Gnutella network crawler equipped with the proposed sampling method and obtain the distribution of ultrapeer lifetimes in a network of 6.4 million users and 60 million links. Our experimental results show that ultrapeer lifetimes are Pareto with shape a alpha ap 1.1; however, link lifetimes exhibit much lighter tails with alpha ap 1.9.","Title: Research on a Super-Sparse Data Generation Model for Temperature Data Map.\nYear: 2013\n\nAbstract: Data visualization is an important method in data mining, and temperature data map is one of the methods of data visualization. When sample temperature points are limited, it brings the main content of the research on how to build a temperature data map, namely how to use super-sparse date to generate a data map. Based on the fact that temperature energy keeps constant, this paper proposes a diffusion model which uses the known temperature data to predict the unknown values. Furthermore, this paper improves the model by adding the influence of wind to make a better temperature data map. Taking the area of Shandong Province as an example, we can only get 17 cities' annual average temperature, then how to make a whole map of Shandong area confronts us. Experimental results verified that the proposed diffusion models turn out to be feasible. © 2013 Springer-Verlag Berlin Heidelberg.","Title: Energy-efficient downlink transmission in multi-cell coordinated beamforming systems\nYear: 2013\n\nAbstract: Coordinated multipoint has been widely introduced to enhance the capacity, especially that of users at cell edge. Recently energy efficient transmission techniques are increasingly important due to the increase of energy consumption in wireless communication systems. In this paper, an energy efficient cooperative transmission algorithm using coordinated beamforming is proposed for multi-cell MIMO networks. We formulate the problem as a non-convex optimization problem in a fractional form. Then we transform the problem into an equivalent form and propose an iterative algorithm to solve it. In each iteration, a simplified zero-forcing coordinated beamforming using beam tracing and an optimal power allocation algorithm for maximizing energy efficiency are derived. Simulation results demonstrate that the proposed algorithm has a better energy efficiency performance than the traditional capacity maximizing method. With the lower complexity, the proposed method using beam tracing approaches the energy efficiency performance of the subspace decomposition method in slowly varying channels.","Title: A Semi-Implicit Scheme for Stationary Statistical Properties of the Infinite Prandtl Number Model\nYear: 2008\n\nAbstract: We propose a semidiscrete in time semi-implicit numerical scheme for the infinite Prandtl model for convection. Besides the usual finite time convergence, this scheme enjoys the additional highly desirable feature that the stationary statistical properties of the scheme converge to those of the infinite Prandtl number model at vanishing time step. One of the key characteristics of the scheme is that it preserves the dissipativity of the infinite Prandtl number model uniformly in terms of the time step. So far as we know, this is the first rigorous result on convergence of stationary statistical properties of numerical schemes for infinite dimensional dissipative complex systems.","Title: Damping Characteristic of Composite Material with Periodic Micro-Tetrahedron Structures\nYear: 2011\n\nAbstract: Research on damping characteristic of structures and materials is always one of the studies of international grand issue. Here, we addressed the damping characteristic of composite material with periodic micro-tetrahedron structures. We estabLished two computational models: one is a composite material model with periodic micro-tetrahedron structure, and another is the mass point model with periodic micro-tetrahedron structures. The unit cell of the first model is the micro-tetrahedron structure, in which the six edges are made of steel, and all the other areas are filled with a kind of high damping material such as rubber. In order to improve the damping characteristic of the first model, we transform the first model into the second model by applying a centraLized mass to the center of every parallelepiped, which consist of six micro-tetrahedron structures. By analyzing and comparing the damping characteristic of the two models, it can be concluded that the damping characteristic of the mass point model is better, and properly choosing the weight of the centraLized mass can improve the damping characteristic of the structure.","Title: A uniformly dissipative scheme for stationary statistical properties of the infinite Prandtl number model\nYear: 2008\n\nAbstract: The purpose of this short communication is to announce that a class of numerical schemes, uniformly dissipative approximations, which uniformly preserve the dissipativity of the continuous infinite dimensional dissipative complex (chaotic) systems possess desirable properties in terms of approximating stationary statistics properties. In particular, the stationary statistical properties of these uniformly dissipative schemes converge to those of the continuous system at vanishing mesh size. The idea is illustrated on the infinite Prandtl number model for convection and semi-discretization in time, although the general strategy works for a broad class of dissipative complex systems and fully discretized approximations. As far as we know, this is the first result on rigorous validation of numerical schemes for approximating stationary statistical properties of general infinite dimensional dissipative complex systems.","Title: Theoretical analysis for solution of support vector data description.\nYear: 2011\n\nAbstract: As we may know well, uniqueness of the Support Vector Machines (SVM) solution has been solved. However, whether Support Vector Data Description (SVDD), another best-known machine learning method, has a unique solution or not still remains unsolved. Due to the fact that the primal optimization of SVDD is not a convex programming problem, it is difficult for us to theoretically analyze the SVDD solution in an analogous way to SVM. In this paper, we concentrate on the theoretical analysis for the solution to the primal optimization problem of SVDD. We first reformulate equivalently the primal optimization problem of SVDD into a convex programming problem, and then prove that the optimal solution with respect to the sphere center is unique, derive the necessary and sufficient conditions of non-uniqueness of the optimal solution with respect to the sphere radius in the primal optimization problem of SVDD. Moreover, we also explore the property of the SVDD solution from the perspective of the SVDD dual form. Furthermore, according to the geometric interpretation of SVDD, a method of computing the sphere radius is proposed when the optimal solution with respect to the sphere radius in the primal optimization problem is non-unique. Finally, we have several examples to illustrate these findings.","Title: ICTSSE: An object-oriented IC test software supporting environment\nYear: 1995\n\nAbstract: An IC test software supporting environment—ICTSSE, which supports the migration and simulation of test pattern programs on\n heterogeneous ATEs, is presented. ICTSSE is a subsystem of Test Development System (TeDS). It has the capabilities of verifying\n the IC’s stimulus/response vectors and associated timing resources against the target ATE. The general data interchange format,\n which is the center of the TEDS, is built for test pattern migration.","Title: An efficient and scalable pairwise key pre-distribution scheme for sensor networks using deployment knowledge\nYear: 2009\n\nAbstract: Pairwise key establishment is a fundamental security service for sensor networks. However, establishing pairwise key in sensor networks is a challenging problem, particularly due to the resource constraints on sensor nodes and the threat of node compromises. On the other hand, adding new nodes to a sensor network is a fundamental requirement for their continuous operation over time, too. We analyze the weaknesses of security due to node capture when adding sensor nodes using key pre-distribution schemes with ''fixed'' key pools. In this paper, we propose a new approach, which separates the nodes into groups, the nodes in a group communicate with each other using pairwise keys pre-distributed, the communications between any two neighbor groups are accomplished also through pairwise keys, which is computed based on the pre-distributed Hash chain. We show that the performance (e.g. continuous connectivity, continuous network resilience against node capture and memory usage) of sensor networks can be substantially improved by using our scheme. The scheme and its detailed performance evaluation are presented.","Title: Dem-Based Study Of Habitat Characteristics Of Torreya Fengqiao In Kuaiji Mountain, China\nYear: 2008\n\nAbstract: The habitat characteristics of Torreya were investigated based oil high resolution DEM and remote sensing image. The distribution of Torreya was mapped by visual interpretation of IKONOS image. The landform and PCA analysis results showed that Curvature, attitude, aspect and slope were found to be the dominant features controlling spatial distribution pattern of Torreya. A certain degree Moisture related variables were proved to be the most important parameters to explain Torreya habitats preferences. The preferable habitat requirement for Torreya focused oil those concave and southwest hillsides with elevation between 400 and 600 in and slope less than 30 degrees.","Title: An Encryption Scheme with Hidden Keyword Search for Outsourced Database.\nYear: 2011\n\nAbstract: An encryption scheme with hidden keyword search is proposed for Outsourced Database. In the proposed scheme, both pseudorandom function and polynomial function are employed in order to reduce computation and shortage overhead. The proposed scheme can not only provide controlled searching, and hidden searching as well as the provable secrecy for encryption, but also support the dynamic change of the permitted group users and be transparent to user when the users are added and removed since they are not involved in the process. Moreover, there is no interaction between database owner and server, server and user or database owner and user when the decrypted key is set up. Each user is only required to receive messages to setup their decrypted key and hence can query over encrypted data and decrypt the encrypted data. Therefore, the proposed scheme is more efficient and more practical for outsourced database. © 2011 ACADEMY PUBLISHER.","Title: Numerical Simulation and Forecasting of Water Level for Qinghai Lake Using Multi-Altimeter Data Between 2002 and 2012\nYear: 2014\n\nAbstract: Satellite radar altimetry has effectively been used for monitoring the water level change in recent years. In this study, Qinghai Lake was taken as an example to simulate and forecast water level using the multi-altimeter data from Envisat/RA-2, Cryosat-2/Siral, and Jason-1/Poseidon-2. First, using the robust least square method and system bias correction algorithms, abnormal water levels and the system bias were eliminated, and an accurate lake-level time series was obtained. Then, singular spectrum analysis (SSA) algorithms were used to extract the effective fluctuation signal from the accurate lake-level time series, and the accuracy of the altimetry data was improved. Based on an analysis of SSA algorithms' characteristics, comparison of the SSA-extracted fluctuation signal, and in-situ gauge measurements of Qinghai Lake, the accurate lake-level time series was affected by white noise of zero-mean and 0.5-m variance and colored noise of 0.2202-0.2473-m mean and 0.252-0.2800-m root-mean-square difference. After eliminating the white noise, the accuracy of the altimeter data reached the decimeter level in inland lake monitoring. Next, the SSA-extracted fluctuation signal was decomposed into linear composition, periodic components, and a residual component, and a combined linear-periodic-residual model was established using simple regression, a trigonometric function, and autoregressive-moving-average models. Using the model, the water level change of Qinghai Lake was simulated and forecasted to 2 years, with its accuracy reaching the decimeter level. The experiences of this study can provide an effective reference for the other lakes.","Title: A Low-Complexity Energy-Efficient Power Allocation and Rate Adaptation Scheme for Relay-Assisted Systems\nYear: 2015\n\nAbstract: In this letter, an energy-efficient power and rate adaptation algorithm for amplify-and-forward (AF) relay systems is studied with imperfect channel statement information (CSI) at transmitters. In the proposed scheme, energy efficiency (EE) is maximized under the maximum transmit power constraint, the minimum system data-rate constraint and the target packet outage probability constraint. In addition, to solve the EE maximization problem, we propose a low-complexity iterative algorithm. Numerical results illustrate the effectiveness of the proposed algorithm.","Title: Energy-Efficient Resource Allocation in Coordinated Downlink Multi-cell OFDMA Systems\nYear: 2016\n\nAbstract: In this paper, a resource allocation algorithm for maximizing the energy efficiency (EE) is studied in multi-cell orthogonal frequency division multiple access (OFDMA) wireless networks. The resource allocation is designed based on imperfect channel state information (CSI). Universal frequency reuse is considered and co-channel interference is dealt with via the cooperation of multiple base stations (BSs) sharing CSI but not user data. We formulate the energy-efficient resource allocation problem as a probabilistic mixed non-convex optimization problem. The user scheduling, data rate adaptation and power allocation are jointly designed to maximize the system EE, under the maximum transmitted power constraint and the outage probability constraint. An iterative algorithm is proposed in which the EE keeps improving until algorithm convergence. In each iteration, the energy-efficient power allocation optimization problem is solved by a lower bound problem and a parameterized transformation. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm. In a multi-cell environment with co-channel interference, the proposed algorithm has large EE gains relative to the spectral efficiency (SE) loss. Compared with non-coordinated methods, the proposed method can achieve higher EE when backhaul power consumption is low.","Title: Secondary use of clinical data: The Vanderbilt approach.\nYear: 2014\n\nAbstract: The last decade has seen an exponential growth in the quantity of clinical data collected nationwide, triggering an increase in opportunities to reuse the data for biomedical research. The Vanderbilt research data warehouse framework consists of identified and de-identified clinical data repositories, fee-for-service custom services, and tools built atop the data layer to assist researchers across the enterprise. Providing resources dedicated to research initiatives benefits not only the research community, but also clinicians, patients and institutional leadership. This work provides a summary of our approach in the secondary use of clinical data for research domain, including a description of key components and a list of lessons learned, designed to assist others assembling similar services and infrastructure.","Title: Stability and bifurcation analysis in a delayed reaction-diffusion malware propagation model\nYear: 2015\n\nAbstract: Mobile wireless sensor networks (MWSNs) have become an area of intense research activity due to technical advances in sensors, wireless communications and networking, and signal processing. Many applications, including environment monitoring, battlefield surveillance, and urban search and rescue especially in hazardous situations, are envisaged. However, MWSNs may be vulnerable to malicious interference because of the large-scale characteristics. When a contaminated node communications with its neighbors, multiple copies of the malware are transmitted to its neighbors, which may destroy, block regular communications, or even damage the integrity of regular data packets. Modeling spatial distribution of malware propagation over time is the first step to predict the trend of malware propagation in MWSNs. We propose a novel wireless malware propagation model with the discrete time delay based on reaction-diffusion equations in mobile wireless sensor networks, and study its dynamic behaviors. By analyzing the stability and Hopf bifurcation of the equilibrium of our model, we search for the sufficient conditions, which leads to the malware propagation disappears or continues. Furthermore, we demonstrate that oscillations in this model occur through the destabilization of the stationary solution at a Hopf bifurcation point. And formulas for determining the stability of the bifurcating periodic oscillations are derived by applying the normal form method and center manifold theorem. Finally, we conduct extensive simulations on large-scale MWSNs to evaluate the proposed model. Numerical evidence shows that the spatial-temporal dynamic characteristics of malware propagation in MWSNs are closely related to the packet transmission rate, the communication rang and the mobile behavior of nodes.","Title: Data integrity verification scheme with designated verifiers for dynamic outsourced databases.\nYear: 2014\n\nAbstract: In order to verify the integrity of the query results in outsourced database model, we first present a new authenticated data structure by combining skip lists with polynomial functions and accumulators and then construct a data integrity verification scheme for range query. Our scheme can verify the integrity of the query results with constant time verification and constant size proof and support dynamic maintenance with constant computational cost. Compared with that of previous schemes, the communication cost in our scheme is independent of the size of the authenticated dataset and is lower. When dataset size gets larger enough, our scheme outperforms previous schemes in terms of the computational cost and verification cost. In addition, we introduce the designated verifier idea into our scheme, so our scheme achieves the result that none but subscribers can verify the integrity of the query results and then meets the practical demands such as the payment service. The proof of security and analysis of experiment performance show that our scheme is secure and efficient for larger outsourced databases. Copyright (c) 2013 John Wiley & Sons, Ltd.","Title: Gene set enrichment analysis for multiple continuous phenotypes.\nYear: 2014\n\nAbstract: Gene set analysis (GSA) methods test the association of sets of genes with phenotypes in gene expression microarray studies. While GSA methods on a single binary or categorical phenotype abounds, little attention has been paid to the case of a continuous phenotype, and there is no method to accommodate correlated multiple continuous phenotypes.We propose here an extension of the linear combination test (LCT) to its new version for multiple continuous phenotypes, incorporating correlations among gene expressions of functionally related gene sets, as well as correlations among multiple phenotypes. Further, we extend our new method to its nonlinear version, referred as nonlinear combination test (NLCT), to test potential nonlinear association of gene sets with multiple phenotypes. Simulation study and a real microarray example demonstrate the practical aspects of the proposed methods.The proposed approaches are effective in controlling type I errors and powerful in testing associations between gene-sets and multiple continuous phenotypes. They are both computationally effective. Naively (univariately) analyzing a group of multiple correlated phenotypes could be dangerous. R-codes to perform LCT and NLCT for multiple continuous phenotypes are available at http://www.ualberta.ca/~yyasui/homepage.html.","Title: Improved pseudo nearest neighbor classification.\nYear: 2014\n\nAbstract: k-Nearest neighbor (KNN) rule is a very simple and powerful classification algorithm. In this article, we propose a new KNN-based classifier, called the local mean-based pseudo nearest neighbor (LMPNN) rule. It is motivated by the local mean-based k-nearest neighbor (LMKNN) rule and the pseudo nearest neighbor (PNN) rule, with the aim of improving the classification performance. In the proposed LMPNN, the k nearest neighbors from each class are searched as the class prototypes, and then the local mean vectors of the neighbors are yielded. Subsequently, we attempt to find the local mean-based pseudo nearest neighbor per class by employing the categorical k local mean vectors, and classify the unknown query patten according to the distances between the query and the pseudo nearest neighbors. To assess the classification performance of the proposed LMPNN, it is compared with the competing classifiers, such as LMKNN and PNN, in terms of the classification error on thirty-two real UCI data sets, four artificial data sets and three image data sets. The comprehensively experimental results suggest that the proposed LMPNN classifier is a promising algorithm in pattern recognition.","Title: Signal power random fading based interference-aware routing for wireless sensor networks\nYear: 2014\n\nAbstract: Power loss and interference coexist in wireless transmissions where random uncertainty is aggravated due to the mobility of sensor nodes. A probability interference model was proposed, based on the physical model and random fading of the received signal power, to depict the uncertainty of wireless interference. In addition, an interference-aware routing metric was designed, in which interference, routing convergence and residual energies of nodes were integrated. Furthermore, an interference-aware probabilistic routing algorithm was proposed for mobile wireless sensor networks, and its correctness and time and space complexities were proved. The NS-2 simulation experiments showed that the proposed algorithm can achieve higher packet delivery ratio than Greedy Perimeter Stateless Routing in various cases like the pause time and maximum moving speed. Simultaneously, the energy consumption of a packet and average delay were taken into consideration to better meet the needs of mobile scenarios with higher reliability.","Title: Study on Sparse Representation based Classification for Biometric Verification.\nYear: 2015\n\nAbstract: In this paper, we propose a multimodal verification system integrating face and ear based on sparse representation based classification (SRC). The face and ear query samples are first encoded separately to derive sparsity-based match scores, and which are then combined with sum-rule fusion for verification. Apart from validating the encouraging performance of SRC-based multimodal verification, this paper also dedicates to provide a clear understanding about the characteristics of SRC-based biometric verification. To this end, two sparsity-based metrics, i.e. spare coding error (SCE) and sparse contribution rate (SCR), are involved, together with face and ear unimodal SRC-based verification. As for the issue that SRC-based biometric verification may suffer from heavy computational burden and verification accuracy degradation with increase of enrolled subjects, we argue that it could be properly resolved by exploiting small random dictionary for sparsity-based score computation, which consists of training samples from a limited number of randomly selected subjects. Experimental results demonstrate the superiority of SRC-based multimodal verification compared to the state-of-the-art multimodal methods like likelihood ratio (LLR), support vector machine (SVM), and the sum-rule fusion methods using cosine similarity, meanwhile the idea of using small random dictionary is feasible in both effectiveness and efficiency.","Title: Energy Efficiency of Cross-Tier Base Station Cooperation in Heterogeneous Cellular Networks.\nYear: 2014\n\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about energy efficiency. Base station (BS) cooperation is set to play a key role in managing interference in the HetNets. In this paper, we consider BS cooperation in the downlink HetNets where BSs from different tiers within the respective cooperative clusters jointly transmit the same data to a typical user, and further optimize the energy efficiency performance. First, based on the proposed clustering model, we derive the spatial average rate using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with a minimum spatial average rate constraint and derive an approximate result of the optimal received signal strength (RSS) thresholds. Building upon these results, we effectively address the problem of how to design appropriate RSS thresholds, taking into account the trade-off between spatial average rate and energy efficiency. Simulations show that our proposed clustering model is more energy-saving than the geometric clustering model, and under our proposed clustering model, deploying a two-tier HetNet is significantly more energy-saving compared to a macro-only network.","Title: Parallel, non-iterative, multi-physics domain decomposition methods for time-dependent Stokes-Darcy systems.\nYear: 2014\n\nAbstract: Two parallel, non-iterative, multi-physics, domain decomposition methods are proposed to solve a coupled time-dependent Stokes-Darcy system with the Beavers-Joseph-Saffman-Jones interface condition. For both methods, spatial discretization is effected using finite element methods. The backward Euler method and a three-step backward differentiation method are used for the temporal discretization. Results obtained at previous time steps are used to approximate the coupling information on the interface between the Darcy and Stokes subdomains at the current time step. Hence, at each time step, only a single Stokes and a single Darcy problem need be solved; as these are uncoupled, they can be solved in parallel. The unconditional stability and convergence of the first method is proved and also illustrated through numerical experiments. The improved temporal convergence and unconditional stability of the second method is also illustrated through numerical experiments.","Title: A second order in time, uniquely solvable, unconditionally stable numerical scheme for Cahn-Hilliard-Navier-Stokes equation\nYear: 2015\n\nAbstract: We propose a novel second order in time numerical scheme for Cahn-Hilliard-Navier-Stokes phase field model with matched density. The scheme is based on second order convex-splitting for the Cahn-Hilliard equation and pressure-projection for the Navier-Stokes equation. We show that the scheme is mass-conservative, satisfies a modified energy law and is therefore unconditionally stable. Moreover, we prove that the scheme is unconditionally uniquely solvable at each time step by exploring the monotonicity associated with the scheme. Thanks to the simple coupling of the scheme, we design an efficient Picard iteration procedure to further decouple the computation of Cahn-Hilliard equation and Navier-Stokes equation. We implement the scheme by the mixed finite element method. Ample numerical experiments are performed to validate the accuracy and efficiency of the numerical scheme.","Title: Unifying Models of Churn and Resilience for Unstructured P2P Graphs\nYear: 2014\n\nAbstract: Previous analytical results on the resilience of unstructured P2P systems have not explicitly modeled heterogeneity of user churn (i.e, difference in online behavior) or the impact of in-degree on system resilience. To overcome these limitations, we introduce a unifying model of heterogeneous user churn and derive the distribution of the various metrics observed in prior experimental studies. We also show that the arrival process of in-edges to each user converges to Poisson when system size tends to infinity, model transient behavior of in-degree, and apply these results to obtain the joint in/out-degree isolation probability.","Title: Approximation algorithms for the three-stage flexible flow shop problem with mid group constraint.\nYear: 2015\n\nAbstract: •We propose ten heuristics for that problem and give their time complexities.•We give 4 lower bounds for that problem and worst case rates of nine heuristics.•We design a computational experiment to test the performance of ten heuristics.•SP.JH-MJ is best and TSM is the worst among the ten heuristics by the experiment.","Title: Energy-efficient base station cooperation in downlink heterogeneous cellular networks\nYear: 2014\n\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about energy efficiency. In this paper, we consider the base station (BS) cooperation solution for improving energy efficiency of the HetNets where BSs from each tier within the cooperative cluster jointly transmit the same data to a typical user. Firstly, based on the proposed clustering model, we precisely derive the ergodic rate expression using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with minimum ergodic rate constraint and derive a closed-form approximated result of the optimal cooperative radii. Building upon these results, we could effectively address the problem how to design appropriate cooperative radii, taking into account the trade-off of ergodic rate and energy efficiency. Simulation results also indicate that under the proposed clustering model, deploying a two-tier HetNet is more energy-saving compared to a macro-only network.","Title: One Kind of Cross-Domain DAA Scheme from Bilinear Mapping\nYear: 2014\n\nAbstract: Direct anonymous attestation was adopted by TCG organization for authenticating remote trusted computing platform. Its advantage is that we can protect the privacy of the platform. Since DAA is a unidirectional authentication, it can't resist the platform masquerading attacks. Because DAA scheme has unidirectional authentication security flaws, the proposed method key negotiation, successfully repairs the defects. In practical applications, there may be a case of multiple trust domains, but most of the existing DAA programs don't support across trust domains. For this limitation, by introducing cross domain certificate issuer, using CL-LRSW signature successfully solve the problem of cross trust domains. After analysis, the scheme satisfies anonymity, enforceability, unlinkability, and can effectively resist platform masquerading attacks.","Title: Graph-theoretic analysis of structured peer-to-peer systems: routing distances and fault resilience\nYear: 2005\n\nAbstract: This paper examines graph-theoretic properties of existing peer-to-peer networks and proposes a new infrastructure based on optimal-diameter de Bruijn graphs. Since generalized de Bruijn graphs exhibit very short average distances and high resilience to node failure, they are well suited for distributed hash tables (DHTs). Using the example of Chord, CAN, and de Bruijn, we study the routing performance, graph expansion, clustering properties, and bisection width of each graph. Having confirmed that de Bruijn graphs offer the best diameter and highest connectivity among the existing peer-to-peer structures, we offer a very simple incremental building process that preserves optimal properties of de Bruijn graphs under uniform user joins/departures. We call the combined peer-to-peer architecture optimal diameter routing infrastructure.","Title: On Static and Dynamic Partitioning Behavior of Large-Scale P2P Networks\nYear: 2008\n\nAbstract: In this paper, we analyze the problem of network disconnection in the context of large-scale P2P networks and understand how both static and dynamic patterns of node failure affect the resilience of such graphs. We start by applying classical results from random graph theory to show that a large variety of deterministic and random P2P graphs almost surely (i.e., with probability 1-o(1)) remain connected under random failure if and only if they have no isolated nodes. This simple, yet powerful, result subsequently allows us to derive in closed-form the probability that a P2P network develops isolated nodes, and therefore partitions, under both types of node failure. We finish the paper by demonstrating that our models match simulations very well and that dynamic P2P systems are extremely resilient under node churn as long as the neighbor replacement delay is much smaller than the average user lifetime.","Title: Long-time dynamics of 2d double-diffusive convection: analysis and/of numerics\nYear: 2015\n\nAbstract: We consider a two-dimensional model of double-diffusive convection and its time discretisation using a second-order scheme (based on backward differentiation formula for the time derivative) which treats the non-linear term explicitly. Uniform bounds on the solutions of both the continuous and discrete models are derived (under a timestep restriction for the discrete model), proving the existence of attractors and invariant measures supported on them. As a consequence, the convergence of the attractors and long time statistical properties of the discrete model to those of the continuous one in the limit of vanishing timestep can be obtained following established methods.","Title: An efficient and long-time accurate third-order algorithm for the Stokes–Darcy system\nYear: 2016\n\nAbstract: Abstract A third-order in time numerical IMEX-type algorithm for the Stokes–Darcy system for flows in fluid saturated karst aquifers is proposed and analyzed. A novel third-order Adams–Moulton scheme is used for the discretization of the dissipative term whereas a third-order explicit Adams–Bashforth scheme is used for the time discretization of the interface term that couples the Stokes and Darcy components. The scheme is efficient in the sense that one needs to solve, at each time step, decoupled Stokes and Darcy problems. Therefore, legacy Stokes and Darcy solvers can be applied in parallel. The scheme is also unconditionally stable and, with a mild time-step restriction, long-time accurate in the sense that the error is bounded uniformly in time. Numerical experiments are used to illustrate the theoretical results. To the authors’ knowledge, the novel algorithm is the first third-order accurate numerical scheme for the Stokes–Darcy system possessing its favorable efficiency, stability, and accuracy properties.","Title: Enhanced algorithm for high-dimensional data classification\nYear: 2016\n\nAbstract: Graphical abstractIllustration of the decision hyperplanes generated by TSSVM, MCVSVM, and LMLP on an artificial dataset. Display Omitted HighlightsIn the case of the singularity of the within-class scatter matrix, the drawbacks of both MCVSVM and LMLP are analyzed.A novel algorithm TSSVM is proposed to deal with the high-dimensional data classification task where the within-class scatter matrix is singular.An alternative version of the nonlinear MCVSVM and the nonlinear LMLP are proposed.The nonlinear TSSVM is developed. Minimum class variance support vector machine (MCVSVM) and large margin linear projection (LMLP) classifier, in contrast with traditional support vector machine (SVM), take the distribution information of the data into consideration and can obtain better performance. However, in the case of the singularity of the within-class scatter matrix, both MCVSVM and LMLP only exploit the discriminant information in a single subspace of the within-class scatter matrix and discard the discriminant information in the other subspace. In this paper, a so-called twin-space support vector machine (TSSVM) algorithm is proposed to deal with the high-dimensional data classification task where the within-class scatter matrix is singular. TSSVM is rooted in both the non-null space and the null space of the within-class scatter matrix, takes full advantage of the discriminant information in the two subspaces, and so can achieve better classification accuracy. In the paper, we first discuss the linear case of TSSVM, and then develop the nonlinear TSSVM. Experimental results on real datasets validate the effectiveness of TSSVM and indicate its superior performance over MCVSVM and LMLP.","Title: Approximate aggregation for tracking quantiles and range countings in wireless sensor networks\nYear: 2015\n\nAbstract: We consider the problem of tracking quantiles and range countings in wireless sensor networks. The quantiles and range countings are two important aggregations to characterize a data distribution. Let S ( t ) = ( d 1 , ¿ , d n ) denote the multi-set of sensory data that have arrived until time t, which is a sequence of data orderly collected by nodes s 1 , s 2 , ¿ , s k . One of our goals is to continuously track ¿-approximate ¿-quantiles ( 0 ¿ ¿ ¿ 1 ) of S ( t ) for all ¿'s with efficient total communication cost and balanced individual communication cost. The other goal is to track ( ¿ , ¿ ) -approximate range countings satisfying the requirement of arbitrary precision specified by different users. In this paper, a deterministic tracking algorithm based on a dynamic binary tree is proposed to track ¿-approximate ¿-quantiles, whose total communication cost is O ( k / ¿ ¿ log ¿ n ¿ log 2 ¿ ( 1 / ¿ ) ) , where k is the number of the nodes in a network, n is the total number of the data, and ¿ is the user-specified approximation error. For range countings, a Bernoulli sampling based algorithm is proposed to track ( ¿ , ¿ ) -approximate range countings, whose total communication cost is O ( 2 ¿ 2 ln ¿ 2 1 - 1 - ¿ + n c ) , where ¿ is the user-specified error probability, n c is the number of clusters.","Title: Energy-efficient resource allocation for OFDMA relay systems with imperfect CSIT\nYear: 2015\n\nAbstract: In this paper, we propose an energy-efficient resource allocation scheme for the downlink of decode-and-forward relay-assisted orthogonal frequency division multiple access systems. The resource allocation is designed based on imperfect channel state information at the transmitter. We jointly optimize the power allocation, data rate allocation, and subcarrier allocation to maximize the system energy efficiency (EE). We formulate the EE problem as a probabilistic mixed non-convex optimization problem, in which the individual power constraints and the outage probability requirements are considered. An iterative algorithm based on bisection method is given to transform the optimization problem into a standard concave form. Also, we consider a proportional fairness design for the EE maximization problem. Simulation results illustrate the effectiveness of the proposed algorithm.","Title: Multiple Base Stations Cooperation: A Novel Clustering Algorithm and Its Energy Efficiency.\nYear: 2016\n\nAbstract: Multiple base stations (BSs) cooperation can effectively reduce the inter-cell interference and especially improve the performance of the cell-edge users, which has been regarded as an important technology in future wireless communication system. All BSs full cooperation is unaffordable for system overhead, so how to partition the BSs in the system into different clusters to cooperate with a low complexity is a challenging issue. In this paper, a novel dynamic clustering algorithm for multiple BSs cooperation in downlink is proposed, and system energy efficiency (EE) is investigated. Firstly, with equal power allocation per symbol and per antenna equal power constraint, the formulas of spectral efficiency (SE) and EE for the case of ideal transmit and the case of actual transmit are derived, respectively. In addition, a novel dynamic clustering algorithm based on channel norm is presented. By calculating the mutual interference matrix according to channel norm, for each clustering judgment, the BS which has the biggest element in the present interference matrix is selected as the leader BS. Then the rest BSs which have the larger interference coefficient with the leader BS are chosen to joint the cluster until the cluster is formed. The computational complexity of the proposed algorithm is analyzed. Simulation results show that EE of the proposed algorithm is better than that of the static clustering one and slightly worse than that of the decentralized algorithm but with a lower complexity.","Title: Kansei engineering, humans and computers: efficient dynamic programming algorithms for combinatorial food packing problems\nYear: 2011\n\nAbstract: The packing system performs an operation of choosing a subset I′ from the set of I of the current n items to produce a package of foods. By repeating the packing operation, it produces a large number of packages one by one. The primary objective is to choose a subset I′ so that the total weight of chosen items is as close to a specified target weight T as possible. We additionally try to maximise the total priority of chosen items as the second objective so that items with longer durations in hoppers are preferably chosen. We show that the combinatorial food packing problem can be solved in O(nT) time if all input data are integral.","Title: Altered Structural And Functional Feature Of Striato-Cortical Circuit In Benign Epilepsy With Centrotemporal Spikes\nYear: 2015\n\nAbstract: Benign epilepsy with centrotemporal spikes (BECT) is the most common form of childhood idiopathic focal epilepsy syndrome. We investigated quantitative evidence regarding brain morphology and functional connectivity features to provide insight into the neuroanatomical foundation of this disorder, using high resolution T1-weighted magnetic resonance imaging (MRI) and resting state functional MRI in 21 patients with BECT and in 20 healthy children. The functional connectivity analysis, seeded at the regions with altered gray-matter (GM) volume in voxel-based morphometry (VBM) analysis, was further performed. Then, the observed structural and functional alteration were investigated for their association with the clinical and behavior manifestations. The increased GM volume in the striatum and fronto-temporo-parietal cortex (striato-cortical circuit) was observed in BECT. The decreased connections were found among the motor network and frontostriatal loop, and between the default mode network (DMN) and language regions. Additionally, the GM of striatum was negatively correlated with age at epilepsy onset. The current observations may contribute to the understanding of the altered structural and functional feature of striato-cortical circuit in patients with BECT. The findings also implied alterations of the motor network and DMN, which were associated with the epileptic activity in patients with BECT. This further suggested that the onset of BECT might have enduring structural and functional effects on brain maturation.","Title: The impact of node velocity diversity on mobile opportunistic network performance\nYear: 2015\n\nAbstract: Mobile opportunistic network is a special kind of mobile ad hoc networks, in which nodes can communicate and interact with each other without a fixed communication infrastructure. Data dissemination between nodes utilizes a store-carry-forward paradigm. In this paper, we explore the impact of node velocity diversity on the performance of mobile opportunistic networks while keeping the average velocity of nodes consistent with each other. The numerical results indicate that greater node velocity diversity always implies longer average communication and the smaller number of communications within the constant total communication time. Thus, it is important to improve the performance of mobile opportunistic networks by adjusting the velocity diversity in response to the requirement of the network and in order to make full use of communication resources. In particular, we construct mathematical models to analyze node contact times and link numbers. Lastly, we verify the correctness of models and theories we proposed by using the Opportunistic Network Environment simulator.","Title: Authenticating multi-dimensional query results in outsourced database.\nYear: 2016\n\nAbstract: In the outsourced database model, the third-party server provides query services to users on behalf of the data owner. However, the service provider may be unreliable or susceptible to attacks. The service provider can also produce inauthentic or incomplete query results. An authentication scheme for multi-dimensional data is proposed in the present study to investigate this problem. The authors i...","Title: A Novel Page Ranking Algorithm Based On Triadic Closure And Hyperlink-Induced Topic Search\nYear: 2015\n\nAbstract: The Hyperlink-Induced Topic Search (HITS) algorithm developed by Jon Kleinberg made use of the link structure of the web pages on the Web in order to discover and rank web pages being relevant to a particular topic. However it only took account of the hyperlink structure, while completely excluded contents of web pages, and it ignored the fact that degrees of the importance of many hyperlinks on the Web may be different. In this paper, to overcome the topic drifts, we proposed a novel page ranking algorithm combining the hyperlink with the triadic closure theory by considering fully the Vector Space Model (VSM) and the TrustRank algorithm. The method firstly computed the relevance between two randomly arbitrary web pages based on web page topic similarity and common reference degree. Then, by using that model as a point of reference, a new adjacency matrix was constructed to iteratively calculate the authority and hub values of web pages. Next, we calculated the trust-degree for each web page in the basic set by the trust-score algorithm. Finally, the score for each web page is computed by linearly merging the authority and the trust-degree. In our experiments, we used five classic HITS-based algorithms to compare with our proposed page ranking algorithm-PCTHITS (Web Page Topic Similarity, Common Reference Degree, Trust-degree) algorithm. The experimental results demonstrated that our proposed algorithm outperform the other four classic improved algorithms and HITS algorithm.","Title: Novel adaptive high-performance and nonlinear filtering algorithm for mixed noise removal\nYear: 2012\n\nAbstract: A novel adaptive high-performance and nonlinear filtering algorithm (AHPNFA) is proposed for the removal of mixed noise from corrupted images. This algorithm contains two stages: noise determining and noise removing. In the first stage, for each filtering window of the processed image, the center pixel and its nearest neighbors are modeled as a statistical variable. By exploiting Chebyshev's theorem, the fuzzy mean process is used to estimate adaptively the detection parameters that are required in determining whether the current pixel is corrupted or not. In the second stage, the Radon transform is performed to determine the texture direction probability density distributions of local areas of images, then using the texture direction probability density distributions and the local features of the image remove the noisy pixels. To demonstrate the advantages, the proposed AHPNFA is compared with the other test filters both visually and quantitatively. Simulation results show that the proposed AHPNFA has better values in important evaluation metrics; in particular, the computational complexity of the AHPNFA is about five to 11 times lower than the other test filters used in the comparison, therefore, the proposed AHPNFA has better performances. (C) 2012 SPIE and IS&T. [DOI: 10.1117/1.JEI.21.2.023005]","Title: Mobility-aware routing in delay tolerant networks\nYear: 2015\n\nAbstract: Delay tolerant networks (DTNs) make use of opportunistic encounters of nodes for communication. The characteristics of high mobility of nodes, frequent link variation and long communication delays in DTNs result in an absence of an instantaneous end-to-end path from any source to a destination, making routing a challenge in DTNs. To deal with this issue, a lot of routing schemes have been proposed, in which future contacts of nodes are predicted based on node mobility traces and contact information. However, the previous works did not consider the spatial information of nodes, such as dwelling time at a location, and the transitivity of contacts in the prediction process of future encounter opportunities of nodes. In this paper, a novel mobility prediction-based routing (MPR) scheme is proposed for DTNs, in which the spatial information of nodes and contact transitivity are both taken into account. Specifically, a time-homogeneous semi-Markov process model is proposed to describe node mobility. By employing the semi-Markov model, we formulate the probability of a node destined to an area subject to the remaining time period constraint. The simulation results show that the proposed MPR scheme substantially improves delivery ratio and reduces delivery latency compared with traditional DTN routing schemes.","Title: Energy-Efficient Resource Allocation In Multi-Cell Ofdma Systems With Imperfect Csi\nYear: 2015\n\nAbstract: In this paper, a resource allocation algorithm for maximizing energy efficiency (EE) is studied in multi-cell orthogonal frequency division multiple access (OFDMA) wireless networks. The resource allocation is designed based on imperfect channel state information (CSI). We formulate the resource allocation problem as a mixed non-convex probabilistic optimization problem. The user scheduling, data rate adaptation and power allocation are jointly designed to maximize the system EE, under the maximum transmitted power constraint and the outage probability constraint. An iterative algorithm is proposed in which the EE keeps improving until algorithm convergence. In each iteration, the energy-efficient power allocation optimization problem is solved by a lower bound problem and a parameterized transformation. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm.","Title: Modeling Propagation Dynamics and Developing Optimized Countermeasures for Rumor Spreading in Online Social Networks\nYear: 2015\n\nAbstract: The spread of rumors in Online Social Networks (OSNs) poses great challenges to the social peace and public order. It is imperative to model propagation dynamics of rumors and develop corresponding countermeasures. Most of the existing works either overlook the heterogeneity of social networks or do not consider the cost of countermeasures. Motivated by these issues, this paper proposes a heterogeneous network based epidemic model that incorporates both the network heterogeneity and various countermeasures. Through analyzing the existence and stability of equilibrium solutions of the proposed ODE (Ordinary Differential Equation) system, the critical conditions that determine whether a rumor continuously propagates or becomes extinct are derived. Moreover, we concern about the cost of the main two types of countermeasures, i.e., Blocking rumors at influential users and spreading truth to clarify rumors. Employing the Pontryagin's maximum principle, we obtain the optimized countermeasures that ensures a rumor can become extinct at the end of an expected time period with lowest cost. Both the critical conditions and the optimized countermeasures provide a real-time decision reference to restrain the rumor spreading. Experiments based on Digg2009 dataset are conducted to evaluate the effectiveness of the proposed dynamic model and the efficiency of the optimized countermeasures.","Title: A Double Pulse Control Strategy For Misinformation Propagation In Human Mobile Opportunistic Networks\nYear: 2015\n\nAbstract: Mobile Opportunistic Networks (MONs) are effective solutions to uphold communications in the situations where traditional communication networks are unavailable. However, MONs can be abused to disseminate misinformation causing undesirable effects in public. To prevent misinformation from propagating, we first propose a formal model to formulate the process of misinformation propagation based on the ordinary differential equation. Secondly, we explore a general framework to describe the random mobility of nodes, and derive a new contact rate between nodes. Thirdly, we propose a double pulse control strategy of vaccination and treatment for inhibiting misinformation propagation. Moreover, a novel pulse control model of misinformation propagation is developed based on the impulsive differential equation. Finally, through the derivation and stability analysis of a misinformation-free period solution of the proposed model, we obtain a threshold upon which misinformation dies out. The simulation results validate our theoretical analysis.","Title: Spacial Mobility Prediction Based Routing Scheme in Delay/Disruption-Tolerant Networks\nYear: 2014\n\nAbstract: Routing is a challenging issue in Delay/Disruption Tolerant Networks (DTNs) due to the characteristics of high mobility of nodes and high dynamicity of network topology. The previous works did not consider the spacial information of nodes, such as dwelling time at a location when predicting the future contact of two nodes. In this paper, a novel Spacial Mobility Prediction based Routing (SMPR) scheme is proposed for DTNs, in which the spacial information of nodes and contact transitivity are both taken into account. Specifically, a time homogeneous semi-Markov process model is proposed to describe the mobility of nodes. The simulation results show that the proposed SMPR scheme substantially improves delivery ratio and reduces delivery latency compared with traditional DTN routing schemes.","Title: FakeMask: A Novel Privacy Preserving Approach for Smartphones.\nYear: 2016\n\nAbstract: Users can enjoy personalized services provided by various context-aware applications that collect users' contexts through sensor-equipped smartphones. Meanwhile, serious privacy concerns arise due to the lack of privacy preservation mechanisms. Currently, most mechanisms apply passive defense policies in which the released contexts from a privacy preservation system are always real, leading to a g...","Title: User-Centric Cross-Tier Base Station Clustering and Cooperation in Heterogeneous Networks: Rate Improvement and Energy Saving.\nYear: 2016\n\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about various costs issues, among which notably is energy efficiency. Base station (BS) cooperation is set to play a key role in managing interference in HetNets. In this paper, we consider BS cooperation in the downlink HetNets where BSs from different tiers within the respective cooperative clusters jointly transmit the same data to a typical user, and in particular focus on the optimization of the energy efficiency performance. First, based on a proposed clustering model, we derive the spectral efficiency using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with a minimum spectral efficiency constraint and derive the optimal received signal strength (RSS) thresholds under certain approximation. Building upon these results, we could address the problem of how to design appropriate RSS thresholds, taking into account the tradeoff between spectral efficiency and energy efficiency. Simulations show that the proposed clustering model is more energy-saving than the geometric clustering model, and deploying a multitier HetNet is significantly more energy-saving compared to a macro-only network.","Title: Principles of the Complete Voronoi Diagram Localization.\nYear: 2016\n\nAbstract: This paper explores the rationale behind the Complete Voronoi Diagram (CVD) Localization, which is a computational geometry approach to the wireless network localization. Our work consists mainly of three parts. The first part focuses on the analysis of CVD's mathematical properties. We characterize CVD's central tendency as the mirror-image distribution and provide mathematical formula for its probability density function. We also provide a closed formula for the relationship between CVD's vertices, chords, and faces, the average chord length, and the average edge number of a CVD polygon. And, the expressions for the average overall and local positioning error are also provided. Based upon these findings, we show that the convergence speed for a CVD based localization scheme is quadratic, and the optimal time and space complexities are (n 2 ) and (n), respectively. The second part proposes a novel approach, called Polling, which utilizes the concept of the Error Region, to further improve the accuracy. Polling, in theory, enables us to make use of the topology information with the quantity up to O(n 4 ) provided by CVD for localization, while a conventional CVD scheme can use only O(1) such information. The third part, through simulations, shows how to use the quasi Analog-to-Digital Conversion (qADC) strategy to handle signal errors. Combined with Polling and qADC, a CVD scheme can provide a simple, robust, and powerful solution to the wireless network localization. Some of our findings and methods may also contribute to the field of computational geometry its own.","Title: Fast 3D-Object Modeling with Kinect and Rotation Platform.\nYear: 2015\n\nAbstract: High-fidelity reconstruction of complete objects is known as a particularly challenging problem. In this paper, we provide a system for object modeling with Kinect and rotation platform. Our modeling solution is divided into three steps: (1) system calibration, (2) Point cloud real time registration,(3) Mesh surface reconstruction and automatic texture mapping. We propose a easy-to-use calibration method for the first step, and based on the calibration result, a automatic texture-independent 3D point clouds registration method is presented. Finally, triangulate meshing and automatic texture mapping technique are used to recreate complete mesh model from the integrated point clouds. Our system is validated by the modeling of several real-world objects, and all the results show its effectiveness.","Title: Exploiting Spectrum Availability And Quality In Routing For Multi-Hop Cognitive Radio Networks\nYear: 2016\n\nAbstract: Cognitive radio networks (CRNs) are considered as a promising solution to the problem of spectrum under utilization and artificial radio spectrum scarcity. The paradigm of dynamic spectrum access allows secondary users (SUs) to utilize wireless spectrum resources which belong to primary users (PUs) with minimal interference to PUs. Due to the dynamic spectrum availability and quality, routing for SUs in multi-hop CRNs is a challenge. In this paper, we introduce novel routing metrics that estimate both the future spectrum availability and the average transmission time. Then, we propose two routing algorithms for multi-hop CRNs that attempt to reduce the probability of spectrum handoff and rerouting upon PU's arrival. Finally, we conduct simulations, whose results show that our proposed algorithms lead to a significant performance improvement over the reference algorithm.","Title: Truthful Incentive Mechanisms for Social Cost Minimization in Mobile Crowdsourcing Systems.\nYear: 2016\n\nAbstract: With the emergence of new technologies, mobile devices are capable of undertaking computational and sensing tasks. A large number of users with these mobile devices promote the formation of the Mobile Crowdsourcing Systems (MCSs). Within a MCS, each mobile device can contribute to the crowdsourcing platform and get rewards from it. In order to achieve better performance, it is important to design a mechanism that can attract enough participants with mobile devices and then allocate the tasks among participants efficiently. In this paper, we are interested in the investigation of tasks allocation and price determination in MCSs. Two truthful auction mechanisms are proposed for different working patterns. A Vickrey-Clarke-Groves (VCG)-based auction mechanism is proposed to the continuous working pattern, and a suboptimal auction mechanism is introduced for the discontinuous working pattern. Further analysis shows that the proposed mechanisms have the properties of individual rationality and computational efficiencies. Experimental results suggest that both mechanisms guarantee all the mobile users bidding with their truthful values and the optimal maximal social cost can be achieved in the VCG-based auction mechanism.","Title: An efficient privacy preserving data aggregation approach for mobile sensing.\nYear: 2016\n\nAbstract: The advances in sensing capabilities of smartphones give rise to a variety of mobile participatory sensing applications that collect users' personal data. Because of the existence of both sensitive, private personal data, and untrusted aggregator, serious privacy concerns on users arise. Currently, existing privacy preserving data collection methods either require bidirectional communications between an untrusted aggregator and mobile users in every aggregation period, or have high computation or communication overhead. To address these problems, we propose an efficient data aggregation approach by which an untrusted aggregator in mobile sensing can collect the statistics over the data contributed by multiple mobile users, while supporting privacy preservation of each user and data integrity verification. In this approach, information hiding and homomorphic encryption are applied to guarantee the data privacy of mobile users. In detail, a breadth-first search tree is first constructed at the initial phase among the mobile users, and then the original datum of each user is perturbed among its neighbors in ciphertext space by using information hiding and homomorphic encryption. The evaluations of our approach show that our protocol requires lower communication and computation overhead and thus more feasible for the computation constrained mobile devices. Copyright © 2016 John Wiley & Sons, Ltd.","Title: Computational models and optimal control strategies for emotion contagion in the human population in emergencies.\nYear: 2016\n\nAbstract: Emotions play an important role in the decision-making of individuals. Emotional contagion has an influence on individual and group-level behaviors. Particularly, the contagion of negative emotions like panic emotions may result in devastating consequences in the human population in emergencies. This work develops novel computational models of emotion contagion and solves the optimal control problem of emotion contagion in the human population in emergencies. Firstly, by introducing a concept of latent state and considering complicated interactions among individuals, we develop a novel conceptual model of emotion contagion, and further establish a computational model for describing the dynamics of emotion contagion, called the susceptible-latent-infectious-recovered-susceptible (SLIRS) model. Secondly, by considering vaccination, quarantine and treatment as control measures, we expand the SLIRS model into a controlled SLIRS model, and formulate the control problem of emotion contagion as an optimal control problem, so that the total costs of inhibiting emotion contagion are minimized. Finally, we theoretically discuss the existence and uniqueness of the solution of the controlled SLIRS model, and further derive an optimal control solution of the controlled SLIRS model. The simulation results on the synthesis dataset and the real trace dataset show that the optimal control strategies have significant impact on emotion contagion. Especially, the optimal control strategy with a mixture of vaccination, quarantine and treatment can significantly decrease the scale of the outbreak of negative emotions, and incur the lowest total costs of inhibiting emotion contagion. This enables the optimal decision-making for inhibiting emotion contagion under the consideration of limited resources in the human population in emergencies. Hence, this work will make contributions to crisis management and crowd evacuation in emergencies.","Title: A Social Motivation-aware Mobility Model for Mobile Opportunistic Networks.\nYear: 2016\n\nAbstract: In mobile opportunistic networks (MONs), human-carried mobile devices such as PDAs and smartphones, with the capability of short range wireless communications, could form various intermittent contacts due to the mobility of humans, and then could use the contact opportunity to communicate with each other. The dynamic changes of the network topology are closely related to the human mobility patterns. In this paper, we propose a social motivation-aware mobility model for MONs, which explains the basic laws of human mobility from the psychological point of view. We analyze and model social motivations of human mobility mainly in terms of expectancy value theory and affiliation motivation. Furthermore, we introduce a new concept of geographic functional cells, which not only incorporates the influence of geographical constraints on human mobility but also simplifies the complicated configuration of simulation areas. Lastly, we validate our model by simulating three real scenarios and comparing it with reality traces and other synthetic traces. The simulation results show that our model has a better match in the performance evaluation when applying social-based forwarding protocols like BUBBULE.","Title: Higher-Load Data Transmitting in Opportunistic Networks Based on Probability Analysis of Communicating Capabilities\nYear: 2016\n\nAbstract: Opportunistic Network has become an international hotspot in according with the popularity of various mobile intelligent terminals. But the nodes with limited communication capabilities cannot satisfy the growing of large content data transmission. Aim to these issues, we propose a novel communication capacity calculation model of Opportunistic Network based on the classical Random Direction mobile model. We observe that different size of fragments in large content represents different delivery delays. Considering that the large content are always the multimedia data, it would necessarily produce additional head-part of every fragment, and this will affect the whole overhead of network. We define the restrain facts model of overhead and put forward an optimal fragment size algorithm. Finally, we designed and evaluated the methods and algorithms in simulate circumstance of Opportunistic Networks. The experiments results show that the average value of contact duration and total times of contacts analyzed from logs are all in according with the contact duration expectation and contact times calculated from the model. The optimal size of fragment is located at the well position in the proper range of fragment size.","Title: Cost-Efficient Strategies for Restraining Rumor Spreading in Mobile Social Networks\nYear: 2017\n\nAbstract: With the popularity of mobile devices, mobile social networks (MSNs) have become an important platform for information dissemination. However, the spread of rumors in MSNs present a massive social threat. Currently, there are two kinds of methods to address this: blocking rumors at influential users and spreading truth to clarify rumors. However, most existing works either overlook the cost of var...","Title: A social activity and physical contact-based routing algorithm in mobile opportunistic networks for emergency response to sudden disasters.\nYear: 2017\n\nAbstract: Sudden disasters such as earthquake, flood and hurricane necessitate the employment of communication networks to carry out emergency response activities. Routing has a significant impact on the functionality, performance and flexibility of communication networks. In this article, the routing problem is studied considering the delivery ratio of messages, the overhead ratio of messages and the average delay of messages in mobile opportunistic networks MONs for enterprise-level emergency response communications in sudden disaster scenarios. Unlike the traditional routing methods for MONS, this article presents a new two-stage spreading and forwarding dynamic routing algorithm based on the proposed social activity degree and physical contact factor for mobile customers. A new modelling method for describing a dynamic evolving process of the topology structure of a MON is first proposed. Then a multi-copy spreading strategy based on the social activity degree of nodes and a single-copy forwarding strategy based on the physical contact factor between nodes are designed. Compared with the most relevant routing algorithms such as Epidemic, Prophet, Labelled-sim, Dlife-comm and Distribute-sim, the proposed routing algorithm can significantly increase the delivery ratio of messages, and decrease the overhead ratio and average delay of messages.","Title: A novel approach for inhibiting misinformation propagation in human mobile opportunistic networks.\nYear: 2017\n\nAbstract: Mobile Opportunistic Networks (MONs) are effective solutions to uphold communications in the situations where traditional communication networks are unavailable. In MONs, messages can be disseminated among mobile nodes in an epidemic and delay-tolerant manner. However, MONs can be abused to disseminate misinformation causing undesirable effects in the general public, such as panic and misunderstanding. To deal with this issue, we first propose a formal model to formulate the process of misinformation propagation in MONs, considering human psychological behaviors. Secondly, we explore a general framework to describe the random node mobility, and derive a new contact rate between nodes, which is closely related to mobility properties of nodes. Thirdly, we propose a novel approach based on vaccination and treatment strategies for inhibiting misinformation propagation in human MONs. Moreover, a novel pulse control model of misinformation propagation is developed. Finally, through the derivation and stability analysis of a misinformation-free period solution of the proposed model, we obtain a threshold upon which misinformation dies out in a human MON. The extensive simulation results validate our theoretical analysis.","Title: Priority queue based polling mechanism on seismic equipment cluster monitoring.\nYear: 2017\n\nAbstract: This paper proposes a passive monitoring system model suitable for seismic observation equipment cluster. Through detailed analysis and design of two key technologies affecting the performance of the system under this model, we pose the priority queue based (PQB) polling mechanism on the cluster node monitoring and the volatility-removed (VR) fault alarm mechanism. New polling mechanism initializes priorities of cluster nodes according to the importance of them, then put them into the polling queue according to the priority order, nodes with same priority follow FCFS algorithm, thus solving problems that important cluster nodes be monitored first. A formula judging whether equipment is in the fluctuant state is given by VR fault alarm mechanism, which improves the accuracy of the monitoring results. Finally, we build an experimental platform to analyze the data of PQB polling and VR warning mechanisms, the conclusion shows that the PQB increases the count of polling nodes than FCFS polling mechanism and VR is more close to the actual fault results than normal alarm mechanism. Furthermore, PQB and VR mechanisms have no significant impact on server performance.","Title: Spectrum-Availability Based Routing for Cognitive Sensor Networks.\nYear: 2017\n\nAbstract: With the occurrence of Internet of Things (IoT) era, the proliferation of sensors coupled with the increasing usage of wireless spectrums especially the ISM band makes it difficult to deploy real-life IoT. Currently, the cognitive radio technology enables sensors transmit data packets over the licensed spectrum bands as well as the free ISM bands. The dynamic spectrum access technology enables secondary users (SUs) access wireless channel bands that are originally licensed to primary users. Due to the high dynamic of spectrum availability, it is challenging to design an efficient routing approach for SUs in cognitive sensor networks. We estimate the spectrum availability and spectrum quality from the view of both the global statistical spectrum usage and the local instant spectrum status, and then introduce novel routing metrics to consider the estimation. In our novel routing metrics, one retransmission is allowed to restrict the number of rerouting and then increase the routing performance. Then, the related two routing algorithms according to the proposed routing metrics are designed. Finally, our routing algorithms in extensive simulations are implemented to evaluate the routing performance, and we find that the proposed algorithms achieve a significant performance improvement compared with the reference algorithm.","Title: Design and Testing of a Parallel Manipulator for Space Micro-vibration Simulation.\nYear: 2017\n\nAbstract: A micro-vibration shaking platform is required for performance testing of sensitive instruments in a micro-vibration environment on-board spacecraft before launch. In this study, a parallel manipulator is designed, which can reproduce 6-DOF space micro-vibrations. The important parts of the manipulator are optimized. Controlling the parallel manipulator is based on transfer function. The control principle and the transfer function testing are introduced. Because of the small structural damping coefficient of the system, the transfer function is simplified from a complex matrix to real matrix. Since the parallel manipulator be-haves slightly nonlinearly, an iterative control strategy is used to approach the desired acceleration step by step. The results from microvibrations testing show that the parallel manipulator can simulate 6DOF space micro-vibrations and the iterative control strategy has better precision for the micro-vibrations control.","Title: Uniquely solvable and energy stable decoupled numerical schemes for the Cahn---Hilliard---Stokes---Darcy system for two-phase flows in karstic geometry\nYear: 2017\n\nAbstract: We propose and analyze two novel decoupled numerical schemes for solving the Cahn---Hilliard---Stokes---Darcy (CHSD) model for two-phase flows in karstic geometry. In the first numerical scheme, we explore a fractional step method (operator splitting) to decouple the phase-field (Cahn---Hilliard equation) from the velocity field (Stokes---Darcy fluid equations). To further decouple the Stokes---Darcy system, we introduce a first order pressure stabilization term in the Darcy solver in the second numerical scheme so that the Stokes system is decoupled from the Darcy system and hence the CHSD system can be solved in a fully decoupled manner. We show that both decoupled numerical schemes are uniquely solvable, energy stable, and mass conservative. Ample numerical results are presented to demonstrate the accuracy and efficiency of our schemes.","Title: Minimum class variance support vector ordinal regression.\nYear: 2017\n\nAbstract: The support vector ordinal regression (SVOR) method is derived from support vector machine and developed to tackle the ordinal regression problems. However, it ignores the distribution characteristics of the data. In this paper, we propose a novel method to handle the ordinal regression problems. This method is referred to as minimum class variance support vector ordinal regression (MCVSVOR). In contrast with SVOR, MCVSVOR explicitly takes into account the distribution of the categories and achieves better generalization performance. Moreover, the problem of MCVSVOR can be transformed into one of SVOR. Thus, the existing software of SVOR can be used to solve the problem of MCVSVOR. In the paper, we first discuss the linear case of MCVSVOR and then develop the nonlinear MCVSVOR through using the kernelization trick. The comprehensive experiment results show that the proposed method is effective and can achieve better generalization performance in contrast with SVOR.","Title: Convergence analysis and error estimates for a second order accurate finite element method for the Cahn-Hilliard-Navier-Stokes system.\nYear: 2017\n\nAbstract: In this paper, we present a novel second order in time mixed finite element scheme for the Cahn–Hilliard–Navier–Stokes equations with matched densities. The scheme combines a standard second order Crank–Nicolson method for the Navier–Stokes equations and a modification to the Crank–Nicolson method for the Cahn–Hilliard equation. In particular, a second order Adams-Bashforth extrapolation and a trapezoidal rule are included to help preserve the energy stability natural to the Cahn–Hilliard equation. We show that our scheme is unconditionally energy stable with respect to a modification of the continuous free energy of the PDE system. Specifically, the discrete phase variable is shown to be bounded in \\(\\ell ^\\infty \\left( 0,T;L^\\infty \\right) \\) and the discrete chemical potential bounded in \\(\\ell ^\\infty \\left( 0,T;L^2\\right) \\), for any time and space step sizes, in two and three dimensions, and for any finite final time T. We subsequently prove that these variables along with the fluid velocity converge with optimal rates in the appropriate energy norms in both two and three dimensions.","Title: MPLB: A Load Balance Scheme of Joint Resource Scheduling in Heterogeneous Wireless Network\nYear: 2017\n\nAbstract: A user terminal with multi-mode wireless interface is always located its position in the covered area of heterogeneous wireless network (HWN), there are too many algorithms about vertical handover (VHO) of multiple attributes decision making (MADM) network selections about HWN. According the analysis of current applications of wireless service, regular service has been classified into four kinds, including voice, video, small data and big data, and the proportions of wireless video and big data service may acquire an unavailable bandwidth for each individual wireless station, which will lead to a heavy load and a lower satisfaction rate. A multiple properties load balance (MPLB) scheme is proposed to solve this joint resource scheduling(JRS) problem properly, MPLB scheme first gave an enhanced architecture including the JSR sub-layer, then model of MPLB is established from the candidate wireless network, five aggregated network performance properties have been defined mathematically, the candidate of best grey relational coefficients (GRC) of grey relational analysis(GRA) algorithm is optimally selected as the final executable scheme, after the description of a general flowchart of MPLB scheme. The simulation results proved the MPLB scheme has a more stable load balance effects than those of VHO, so did most users of MPLB gain higher satisfaction rate, slightly different with the four kinds of service. It can be concluded theoretically that the MPLB scheduling scheme could achieve both the load balance on the service providers side and the increased quality of experience of satisfaction rate on the wireless user side, which would bring out some new thoughts in the future user centric network.","Title: CPC: A novel content popularity compensation algorithm for intelligent wireless router in user centric network\nYear: 2017\n\nAbstract: User centric network (UCN) brought a new concept of all routers to be intelligent and definable, intelligent wireless terminals implement more video online service than general webpage exploring service, in the time of content is the king, how to provide a best user experience for the video content user under intelligent wireless routers(IWR) is a key focus in the current research of user centric network. This paper proposed a scheme of intelligent pipe between Policy server and IWR, and designed a novel content popularity compensation (CPC) algorithm in user centric network framework, the IWR obtained the user attributes and video content popularity, used the parameter of content popularity compensation index (CPI) to integrate the classified user weight (CUW) and content popularity level (CPL), the modified satisfaction degree (MSD) was designed to replace of the general index of user satisfaction degree, such as linear satisfaction degree (LSD) and simple logarithmic satisfaction (SLS). The scheduling rule was to get a maximized system MSD, and the measurement of user average satisfaction (UAS) was the evaluation standard of CPC. The simulations results showed that the CPC got the better performance than that of routine algorithms, such as max-min fairness (MMF) and Utility function (ULF), the CPC algorithm could push on the intelligent wireless router in smart home and bring a novel video content quality of experience (QoE) of future wireless video online users.","Title: A social-aware probabilistic routing approach for mobile opportunistic social networks.\nYear: 2017\n\nAbstract: In mobile opportunistic social networks (MOSNs), mobile users move around and conduct message transmission by using their portable devices without the support of communication infrastructures, in which routing is a challenge due to high connection intermittency and node mobility. The current routing schemes for MOSNs only focus on the improvement of cost-effective delivery by using the characteristics of users' interests or mobility. In this paper, we propose a novel routing approach for MOSNs in which the probabilistic and social-aware strategies are combined and the multiple-copy policy is adopted. We first model an MOSN into some overlapping regions and then propose 2 region-related centrality degrees related to users' social characteristics with the consideration of users' centrality, mobility, and interactions among users. According to the definition of centrality degrees, we design a social-aware probabilistic routing approach in which a message replica control policy is applied to allow a user with higher encounter probability to the destination and the user could obtain more message replicas. The simulation results show that the proposed approach outperforms the previous routing algorithms in terms of delivery ratio and overhead ratio.","Title: An Edge Correlation Based Differentially Private Network Data Release Method.\nYear: 2017\n\nAbstract: Differential privacy (DP) provides a rigorous and provable privacy guarantee and assumes adversaries' arbitrary background knowledge, which makes it distinct from prior work in privacy preserving. However, DP cannot achieve claimed privacy guarantees over datasets with correlated tuples. Aiming to protect whether two individuals have a close relationship in a correlated dataset corresponding to a weighted network, we propose a differentially private network data release method, based on edge correlation, to gain the tradeoff between privacy and utility. Specifically, we first extracted the Edge Profile (PF) of an edge from a graph, which is transformed from a raw correlated dataset. Then, edge correlation is defined based on the PFs of both edges via Jenson-Shannon Divergence (JS-Divergence). Secondly, we transform a raw weighted dataset into an indicated dataset by adopting a weight threshold, to satisfy specific real need and decrease query sensitivity. Furthermore, we propose epsilon-correlated edge differential privacy (CEDP), by combining the correlation analysis and the correlated parameter with traditional DP. Finally, we propose network data release (NDR) algorithm based on the epsilon-CEDP model and discuss its privacy and utility. Extensive experiments over real and synthetic network datasets show the proposed releasing method provides better utilities while maintaining privacy guarantee.","Title: An Efficient Context-Aware Privacy Preserving Approach for Smartphones.\nYear: 2017\n\nAbstract: With the proliferation of smartphones and the usage of the smartphone apps, privacy preservation has become an important issue. The existing privacy preservation approaches for smartphones usually have less efficiency due to the absent consideration of the active defense policies and temporal correlations between contexts related to users. In this paper, through modeling the temporal correlations among contexts, we formalize the privacy preservation problem to an optimization problem and prove its correctness and the optimality through theoretical analysis. To further speed up the running time, we transform the original optimization problem to an approximate optimal problem, a linear programming problem. By resolving the linear programming problem, an efficient context-aware privacy preserving algorithm (CAPP) is designed, which adopts active defense policy and decides how to release the current context of a user to maximize the level of quality of service (QoS) of context-aware apps with privacy preservation. The conducted extensive simulations on real dataset demonstrate the improved performance of CAPP over other traditional approaches.","Title: Revocable Key-Aggregate Cryptosystem for Data Sharing in Cloud\nYear: 2017\n\nAbstract: AbstractWith the rapid development of network and storage technology, cloud storage has become a new service mode, while data sharing and user revocation are important functions in the cloud storage. Therefore, according to the characteristics of cloud storage, a revocable key-aggregate encryption scheme is put forward based on subset-cover framework. The proposed scheme not only has the key-aggregate characteristics, which greatly simplifies the user’s key management, but also can revoke user access permissions, realizing the flexible and effective access control. When user revocation occurs, it allows cloud server to update the ciphertext so that revoked users can not have access to the new ciphertext, while nonrevoked users do not need to update their private keys. In addition, a verification mechanism is provided in the proposed scheme, which can verify the updated ciphertext and ensure that the user revocation is performed correctly. Compared with the existing schemes, this scheme can not only reduce the cost of key management and storage, but also realize user revocation and achieve user’s access control efficiently. Finally, the proposed scheme can be proved to be selective chosen-plaintext security in the standard model.","Title: Resource allocation in OFDMA heterogeneous networks for maximizing weighted sum energy efficiency.\nYear: 2017\n\nAbstract: In this paper, a resource allocation algorithm for maximizing the weighted sum energy efficiency (EE) is investigated in orthogonal frequency division multiple access (OFDMA) heterogeneous networks (Het-Nets). We aim to balance the EE of macro cell and low power nodes by subchannel and power allocations. We formulate the problem as a nonlinear sum-of-ratios programming issue, and guarantee data rate requirements of users by using minimum rate constraints. Due to the nonconvexity of the problem, we develop a heuristic subchannel assignment algorithm, and then solve the power allocation problem by parameterized transformations and a first-order approximation based on an iterative algorithm. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm.","Title: Primary and Secondary Social Activity Aware Routing for Cognitive Radio Networks\nYear: 2016\n\nAbstract: In cognitive radio networks (CRNs), efficient spectrum access is challenging and whitespace are necessary for communicating pairs, including Primary Users (PUs) and Secondary Users (SUs). In the existing works, available whitespace is determined by PUs' social activities, which has drawn much attention and been investigated. In reality, SUs need to compete with each other in obtaining accessible whitespace. To the best of our knowledge, the modeling and integration of SUs' social activities have not been considered in real whitespace analysis. Inspired by this motivation, we propose an solution aiming to attaining accessible whitespace, which considers the available whitespace determined by primary activities and the competitions based on secondary activities. Furthermore, we take a spectrum aware routing, including accessible whitespace and routing convergence, as an example to demonstrate the advantage of this proposed solution. The simulation experiments conducted on real world datasets verify the difference between available whitespace and accessible whitespace, and also show the adaptiveness of the proposed algorithm in terms of average delivery ratio and average delay.","Title: An on-demand coverage based self-deployment algorithm for big data perception in mobile sensing networks.\nYear: 2018\n\nAbstract: Mobile Sensing Networks have been widely applied to many fields for big data perception such as intelligent transportation, medical health and environment sensing. However, in some complex environments and unreachable regions of inconvenience for human, the establishment of the mobile sensing networks, the layout of the nodes and the control of the network topology to achieve high performance sensing of big data are increasingly becoming a main issue in the applications of the mobile sensing networks. To deal with this problem, we propose a novel on-demand coverage based self-deployment algorithm for big data perception based on mobile sensing networks in this paper. Firstly, by considering characteristics of mobile sensing nodes, we extend the cellular automata model and propose a new mobile cellular automata model for effectively characterizing the spatial–temporal evolutionary process of nodes. Secondly, based on the learning automata theory and the historical information of node movement, we further explore a new mobile cellular learning automata model, in which nodes can self-adaptively and intelligently decide the best direction of movement with low energy consumption. Finally, we propose a new optimization algorithm which can quickly solve the node self-adaptive deployment problem, thus, we derive the best deployment scheme of nodes in a short time. The extensive simulation results show that the proposed algorithm in this paper outperforms the existing algorithms by as much as 40% in terms of the degree of satisfaction of network coverage, the iterations of the algorithm, the average moving steps of nodes and the energy consumption of nodes. Hence, we believe that our work will make contributions to large-scale adaptive deployment and high performance sensing scenarios of the mobile sensing networks.","Title: Dynamic Adjustment Strategy of n-Epidemic Routing Protocol for Opportunistic Networks: A Learning Automata Approach.\nYear: 2017\n\nAbstract: In order to improve the energy efficiency of n-Epidemic routing protocol in opportunistic networks, in which a stable end-to-end forwarding path usually does not exist, a novel adjustment strategy for parameter n is proposed using learning atuomata principle. First, nodes dynamically update the average energy level of current environment while moving around. Second, nodes with lower energy level relative to their neighbors take larger n avoiding energy consumption during message replications and vice versa. Third, nodes will only replicate messages to their neighbors when the number of neighbors reaches or exceeds the threshold n. Thus the number of message transmissions is reduced and energy is conserved accordingly. The simulation results show that, n-Epidemic routing protocol with the proposed adjustment method can efficiently reduce and balance energy consumption. Furthermore, the key metric of delivery ratio is improved compared with the original n-Epidemic routing protocol. Obviously the proposed scheme prolongs the network life time because of the equilibrium of energy consumption among nodes.","Title: Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers.\nYear: 2018\n\nAbstract: The real-time State Space Representation (SSR) product of the GNSS (Global Navigation Satellite System) orbit and clock is one of the most essential corrections for real-time precise point positioning (PPP). In this work, the performance of current SSR products from eight analysis centers were assessed by comparing it with the final product and the accuracy of real-time PPP. Numerical results showed that (1) the accuracies of the GPS SSR product were better than 8 cm for the satellite orbit and 0.3 ns for the satellite clock; (2) the accuracies of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) SSR product were better than 10 cm for orbit RMS (Root Mean Square) and 0.6 ns for clock STD (Standard Deviation); and (3) the accuracies of the BDS (BeiDou Navigation Satellite System) and Galileo SSR products from CLK93 were about 14.54 and 4.42 cm for the orbit RMS and 0.32 and 0.18 ns for the clock STD, respectively. The simulated kinematic PPP results obtained using the SSR products from CLK93 and CLK51 performed better than those using other SSR products; and the accuracy of PPP based on all products was better than 6 and 10 cm in the horizontal and vertical directions, respectively. The real-time kinematic PPP experiment carried out in Beijing, Tianjin, and Shijiazhuang, China indicated that the SSR product CLK93 from Centre National d'Etudes Spatiales (CNES) had a better performance than CAS01. Moreover, the PPP with GPS + BDS dual systems had a higher accuracy than those with only a GPS single system.","Title: Configuration Analysis and Design of a Multidimensional Tele-operator Based on a 3-P(4S) Parallel Mechanism.\nYear: 2018\n\nAbstract: Based on configuration analysis, different types of 3-P(4S) parallel mechanisms are designed and introduced in this paper. Application issues of parallel mechanisms are discussed and a double 3-P(4S) mechanism-based tele-operator is illustrated. Inverse and forward kinematics of the single 3-P(4S) parallel mechanism are derived and solved via MATLAB software; based on it, the workspace of the 3-P(4S) parallel mechanism is investigated. The relationship between the distribution angle of kinematic chain and volume of the workspace is derived, and the shapes of the workspace of single and double 3-P(4S) parallel mechanisms are plotted. A prototype is developed and an interactive simulation system is established based on SolidWorks and LabVIEW software. Testing results indicate that the proposed tele-operator can well perform tele-operation tasks. This research work lays a good basis for performances evaluation and parameter optimization of 3-P(4S) mechanisms. Besides, it provides new ideas for the applications of parallel mechanisms.","Title: A Routing Algorithm Based on the Prediction of Node Meeting Location in Opportunistic Networks.\nYear: 2017\n\nAbstract: The opportunistic network is a kind of self-organizing network which makes use of the meeting opportunities created by moving nodes to realize short-distance wireless communication, in which the dynamic characteristics of the network topology often result in low communication efficiency. To improve the efficiency of messages transmission, firstly we combine the Markov model to establish a node location prediction model and a distance prediction and calculation model between nodes respectively in order to accurately predict the location of the nodes at the next moment and calculate the distance between nodes; secondly based on the significance and timelessness of messages, a priority based buffer management strategy is proposed to realize the efficient use of buffer. Finally in this paper we propose an efficient opportunistic network routing algorithm, named LIBR, based on the prediction of node meeting location to forward the messages. Compared with the well-known routing algorithms, the simulation results show that our proposed algorithm can significantly improve the delivery ratio, reduce the overhead ratio and average delay of messages.","Title: An Efficient Routing Algorithm Based on Interest Similarity and Trust Relationship Between Users in Opportunistic Networks.\nYear: 2017\n\nAbstract: In opportunistic networks, due to the randomness of node moving and the uncertainty of network topology, it's a challenging issue to establish a complete communication link between the source and the destination node. Fortunately, the \"store-carry-forward\" strategy can be used to solve this problem. However, such forwarding strategy heavily relies on the cooperation among nodes. Thus, the selection of a proper relay node has a great impact on the performance of the whole network. In this paper, considering the differences between users' interest and the variability of interest with the change of time, firstly, we propose a dynamic update and calculation method of the value of interests, and then establish a calculation model of interest. Secondly, according to the Ebbinghaus forgetting curve and the ability of users to forward messages, we propose a dynamic calculation method of the trust value of users and establish a model for computing trust relationships. Finally, we propose an efficient routing algorithm based on interest similarity and trust relationship (BIST) between users. The simulation results show that our proposed algorithm has better routing performance, and it validates the correctness and validity of our proposed models and algorithm.","Title: An Efficient Energy-Aware Probabilistic Routing Approach For Mobile Opportunistic Networks\nYear: 2018\n\nAbstract: Routing is a concerning and challenging research hotspot in Mobile Opportunistic Networks (MONs) due to nodes' mobility, connection intermittency, limited nodes' energy and the dynamic changing quality of the wireless channel. However, only one or several of the above factors are considered in most current routing approaches. In this paper, we propose an efficient energy-aware probabilistic routing approach for MONs. Firstly, we explore and exploit the regularity of nodes' mobility and the encounter probability among nodes to decide the time when to forward messages to other nodes. Secondly, by controlling the energy fairness among nodes, we try to prolong the network lifetime. Thirdly, by fully taking the dynamic changing quality of the wireless channel into consideration, we effectively reduce the retransmission number of messages. Additionally, we adopt a forwarding authority transfer policy for each message, which can effectively control the number of replicas for each message. Simulation results show that the proposed approach outperforms the existing routing algorithms in terms of the delivery ratio and the overhead ratio.","Title: Leveraging Neighborhood Summaries for Efficient Queries on Existing Relational RDF Systems\nYear: 2017\n\nAbstract: Using structural informations to summarize graph-structured RDF data is helpful in tackling query performance issues. However, leveraging structural indexes needs to revise or even redesign the internal of RDF systems. Given an RDF dataset that have already been bulk loaded into a relational RDF system, we aim at improving the query performance on such systems. We do so by summarizing neighborhood structures and encoding them into triples which can be managed along side the exist instance data. At query time, we optimally select the effective structural patterns, and adding these patterns to the existing queries to gain an improved query performance. Empirical evaluations shown the effectiveness of our method.","Title: Querying Rdf Graphs Over Partitioned Indexes\nYear: 2017\n\nAbstract: We consider the problem of improving the query response time over a large-scale RDF collection. Existing methods need to maintain either all intermediate results or all graph structured data, which result in efficiency problems for complex queries. Our main idea is to introduce a two-level processing. The first level is performed as subgraph matching over a partition-based summary graph, which output coarse-grained matched partitions in a stream fashion. Then the fine-grained joins are processed on the matched partitions and generates the final results. Our method is efficient in that it avoid processing on large SPO permutation index at query time. An extensive experimental study using benchmark and real dataset shows that the query performance of our approach outperforms existing systems by orders of magnitudes.","Title: User social activity-based routing for cognitive radio networks.\nYear: 2018\n\nAbstract: The social activities of Primary Users (PUs) and Secondary Users (SUs) affect actual accessible whitespace in Cognitive Radio Networks (CRNs). However, the impacts of primary activities on available whitespace have been extensively investigated due to the dominating priority of PUs, while the impacts of secondary activities on actual accessible whitespace have been ignored. Therefore, we propose to incorporate the primary and secondary activities in the analysis and decision of the accessible whitespace, namely, both the dominance of PUs over SUs and the competitions among SUs are simultaneously taken into account. Specifically, we first approximate primary activity probability based on the real datasets of mobile phone usage records, then the spectrum opportunity between a pair of communication SUs is deduced based on primary activities. Next, we infer the access probability limit of SUs successfully accessing the whitespace according to the primary activity probability, and depict the secondary activity probability from the views of social activity patterns and social networks respectively. Furthermore, the actual accessible probability of whitespace is given by introducing the competitions among SUs. Finally, a greedy routing algorithm, considering the accessible whitespace and the distance to the destination, is proposed to verify our idea. The experiment results based on the real datasets demonstrate the correctness of our analysis and the advantages of the proposed algorithm.","Title: A CTMDP-Based Exact Method for RCPSP with Uncertain Activity Durations and Rework.\nYear: 2017\n\nAbstract: Many practical projects incorporate random rework, which leads to a stochastic project network structure. Until now, however, there have been only few works in the literature that have looked into this particular aspect of project planning and scheduling. In this paper, we consider a resource-constrained project scheduling problem (RCPSP) with exponentially distributed activity durations and two types of random rework. A mathematical model is proposed based on a continuous-time Markov decision process (CTMDP) with the objective to minimize the expected project makespan, which is further converted into an equivalent DTMDP with removing the self-transitions. In order to cope with the curse of dimensionality that comes into play upon solving large-scale instances, we examine a decomposition and parallel method that limits the memory usage. In addition, we also analyze the effect of random rework on the expected project makespan and the optimal rework strategy. Finally, a computational experiment is set up to validate the effectiveness of the proposed model and procedures.","Title: A hybrid short-term traffic flow forecasting model based on time series multifractal characteristics.\nYear: 2018\n\nAbstract: Short-term traffic flow forecasting is a key problem in the area of intelligent transportation systems (ITS). Timely and accurate traffic state prediction is also the prerequisite of realizing proactive traffic control and dynamic traffic assignment effectively. In this paper, a new hybrid model for short-term traffic flow forecasting, which is built based on multifractal characteristics of traffic flow time series, is proposed. The hybrid model decomposes traffic flow series into four different components, namely a periodic part, a trend part, a stationary part and a volatility part, to unearth the traffic features hidden behind the data. Four parts are treated and modeled separately by using different methods, such as spectral analysis, time series and statistical volatility analysis, to further explore the underlying traffic patterns and improve forecasting accuracy. Performance of the proposed hybrid model is investigated with traffic flow data from freeway I-694 EB in the Twin Cities. The experimental results indicate that the proposed model outperforms in capturing nonlinear volatility and improving forecasting accuracy than traditional forecasting methods, especially for the multi-step ahead forecasting. Compared with the ARIMA-GARCH model, it gets an improvement of 8.23% in RMSE for one-step ahead forecasting and 10.69% for ten-step ahead forecasting. It is better than the hybrid model newly proposed in literature (Zhang et al. Transp Res Part C: Emerg Technol 43(1):65–78 2014) and gets an improvement of 1.27% in forecasting accuracy.","Title: Velocity Control Based on Active Disturbance Rejection for Air-Breathing Supersonic Vehicles.\nYear: 2018\n\nAbstract: This paper investigates a velocity tracking control approach for air-breathing supersonic vehicles with uncertainties and external disturbances. Considering angle of attack is difficult to be precisely measured in practice, extended state observer technique is introduced into the state reconstruction design. In order to avoid possible oscillations in the design of the traditional extended state observer (TESO), a modified extended state observer (MESO) is developed, where a new smooth function is proposed to replace nonsmooth function of TESO. On the basis of it, an active disturbance rejection controller (ADRC) is designed for velocity control systems. Simultaneously, the closed-loop stability is rigorously proved by using Lyapunov theory. Finally, numeric simulations are conducted to validate the effectiveness of the proposed method.","Title: ROSIE: Runtime Optimization of SPARQL Queries over RDF Using Incremental Evaluation.\nYear: 2018\n\nAbstract: RDF (Resource Description Framework) is a proposed standard for knowledge representation, with relational databases wildly adopted in RDF data management. For efficient evaluation of SPARQL queries over RDF data, the legacy query optimizer needs reconsiderations. One vital problem is how to tackle the suboptimal query plan caused by error-prone cardinality estimation. For RDF data, determine an optimal execution order before the query actually evaluated is costly, or even infeasible. In this paper, we propose ROSIE, a Runtime Optimization framework that iteratively re-optimize SPARQL query plan according to the actual cardinality derived from Incremental partial query Evaluation. By introducing an approach for heuristic-based plan generation, as well as a mechanism to detect cardinality estimation error at runtime, ROSIE relieves the problem of biased cardinality propagation in an efficient way. Extensive experiments on real and benchmark data have shown that, compared to the state-of-the-arts, ROSIE consistently outperformed on complex queries by orders of magnitude.","Title: Verifiable Public Key Encryption With Keyword Search Based on Homomorphic Encryption in Multi-User Setting.\nYear: 2018\n\nAbstract: Data security and privacy concerns are important issues in cloud storage. In this paper, we propose a verifiable public key encryption with keyword search based on homomorphic encryption in multi-user setting. By employing van Dijk, Gentry, Halevi, and Vaikuntanathan homomorphic encryption, the proposed scheme enables the cloud server to generate an inverted encryption index structure without using a query trapdoor, which significantly improves the efficiency of search. On the other hand, the proposed scheme presents a new authenticated data structure based on the inverted encryption index structure, and shows how to apply it to verify the correctness and completeness of search results. Moreover, the proposed scheme allows multiple users to perform encrypted keyword search over encrypted data. Finally the proposed scheme is proved secure based on the approximate-GCD problem. The experiment results demonstrate the proposed scheme has less computation overhead than the existing schemes.","Title: Reaction-diffusion equation based image restoration.\nYear: 2018\n\nAbstract: We present a novel restoration algorithm based on the reaction–diffusion equation theory, denominated RDER, for restoring images which are corrupted by various blur PSFs and different types of noise (including different levels of impulse noise, Gaussian noise and mixed noise). The focus of this work is to propose an image restoration method based on the reaction diffusion equation and to further extend the traditional diffusion equation. Firstly, the RDER model is constructed by using the restoration ability of the diffusion equation, and the image detail preservation ability of the reaction equation; secondly, based on the difference scheme theory, a discrete RDER model is proposed for image restoration and a RDER algorithm for restoring the image is designed; thirdly, we mathematically analyze the RDER model from the existence, stability and uniqueness of solutions of the RDER model; finally, the proposed RDER algorithm is compared with the current famous state-of-the-art restoration algorithms in image restoring and image details preserving. Theoretical analysis and extensive experimental results show that the RDER is an effective image restoration algorithm for image denoising, image deblurring and image details preserving; in particular, the RDER provides a better performance in terms of the impulse noise and mixed noise.","Title: A multivariate short-term traffic flow forecasting method based on wavelet analysis and seasonal time series.\nYear: 2018\n\nAbstract: Short-term traffic flow forecasting is a key step to achieve the performance of intelligent transportation system (ITS). Timely and accurate traffic information prediction is also the prerequisite of realizing proactive traffic control and dynamic traffic assignment effectively. Based on the fact that univariate forecasting methods have limited forecasting abilities when the data is missing or erroneous and that single models make no full use of information underline data, a new hybrid method with multivariate for short-term traffic flow forecasting is proposed. This method combines statistical analysis method with computational intelligence techniques to mine the characteristic of traffic flow as well as forecast short-term traffic state. First, the wavelet de-noising is employed to remove the noise information. Then, time series analysis is used to analyze time-varying and periodic characteristic of traffic flow. Furthermore, the seasonal auto-regressive moving average with external input (SARIMAX) is established to fit traffic flow with occupancy as exogenous variables. Finally, wavelet forecast is adopted to forecast the values of occupancy which are used as exogenous input, and a WSARIMAX is constructed to forecast traffic flow. Using the relationship of flow and occupancy at the same road section and taking traffic flow and occupancy data from freeway I-694 EB in the Twin Cities as endogenous variables and exogenous variables respectively, this paper studies the forecasting performance of the proposed method. The study results are encouraging. Compared with SARIMA newly proposed in literature, WSARIMA and SARIMAX improved method with wavelet analysis and multivariate modeling method, the proposed method gets improvements of 12.95%, 12.62% and 10.41% in forecasting accuracy of one-step ahead respectively. For ten-steps ahead forecasting, it gets improvements of 18.87%, 17.05% and 2.57% in forecasting accuracy respectively.","Title: A Second Order in Time, Decoupled, Unconditionally Stable Numerical Scheme for the Cahn-Hilliard-Darcy System.\nYear: 2018\n\nAbstract: We propose a novel second order in time, fully decoupled and unconditionally stable numerical scheme for solving the Cahn–Hilliard–Darcy system which models two-phase flow in porous medium or in a Hele–Shaw cell. The scheme is based on the ideas of second order convex-splitting for the Cahn–Hilliard equation and pressure-correction for the Darcy equation. The computation of order parameter, pressure and velocity is completely decoupled in our scheme. We show that the scheme is uniquely solvable, unconditionally energy stable and mass-conservative. Ample numerical results are presented to gauge the efficiency and robustness of our scheme.","Title: Proteus: network-aware web browsing on heterogeneous mobile systems\nYear: 2018\n\nAbstract: ABSTRACTWe present Proteus, a novel network-aware approach for optimizing web browsing on heterogeneous multi-core mobile systems. It employs machine learning techniques to predict which of the heterogeneous cores to use to render a given webpage and the operating frequencies of the processors. It achieves this by first learning offline a set of predictive models for a range of typical networking environments. A learnt model is then chosen at runtime to predict the optimal processor configuration, based on the web content, the network status and the optimization goal. We evaluate Proteus by implementing it into the open-source Chromium browser and testing it on two representative ARM big.LITTLE mobile multi-core platforms. We apply Proteus to the top 1,000 popular websites across seven typical network environments. Proteus achieves over 80% of best available performance. It obtains, on average, over 17% (up to 63%), 31% (up to 88%), and 30% (up to 91%) improvement respectively for load time, energy consumption and the energy delay product, when compared to two state-of-the-art approaches.","Title: Assessment of cerebral blood flow in neonates and infants: A phase-contrast MRI study.\nYear: 2019\n\nAbstract: Abnormal cerebral blood flow (CBF) is implicated in several neonatal and infant diseases. However, measurement of CBF in this population remains difficult and has not been used in routine clinical MRI. Arterial spin labeling (ASL) methods suffer from both low SNR and poor quantification when applied to very young children. Furthermore, rapid change in brain physiology in this age range makes it difficult to choose sequence parameters such as labeling pulse flip angle and post labeling delay. Phase-contrast (PC) MRI is another approach to measure flow. It provides fast and reliable global CBF assessment, and has great promises in pediatric applications. In this study, we aimed to apply PC-MRI technique for CBF quantification in neonates and infants up to 18 months of age. We first compared several implementations of time-of-flight (TOF) MR angiogram for the visualization of brain's feeding arteries, which provides anatomical information for the positioning of PC-MRI scans. We then measured flow velocity and CBF of the internal carotid artery (ICA) and vertebral artery (VA) in 21 subjects (age 34–114 gestational weeks, 3 females, 18 males), using six encoding velocities (Venc) in each vessel. In ICA, peak arterial flow velocity was 10.2 cm/s at birth and increased to 56.0 cm/s at 18 months old. These values were 4.5–36.3 cm/s, respectively, for VA. CBF after accounting for brain volume revealed a significant (p < 0.001) age-related increase from 13.1 to 84.7 ml/100 g/min within the first 18 months after birth. Based on the peak flow velocity, we provided age-specific recommendations for Venc selection in PC-MRI when one only has time for one scan. The present study used a multi-Venc scheme to determine flow velocities in major feeding arteries of infant brain and may lay a foundation for accurate measurement of whole-brain CBF in this population.","Title: Big data management challenges in health research-a literature review.\nYear: 2019\n\nAbstract: Big data management for information centralization (i.e. making data of interest findable) and integration (i.e. making related data connectable) in health research is a defining challenge in biomedical informatics. While essential to create a foundation for knowledge discovery, optimized solutions to deliver high-quality and easy-to-use information resources are not thoroughly explored. In this review, we identify the gaps between current data management approaches and the need for new capacity to manage big data generated in advanced health research. Focusing on these unmet needs and well-recognized problems, we introduce state-of-the-art concepts, approaches and technologies for data management from computing academia and industry to explore improvement solutions. We explain the potential and significance of these advances for biomedical informatics. In addition, we discuss specific issues that have a great impact on technical solutions for developing the next generation of digital products (tools and data) to facilitate the raw-data-to-knowledge process in health research.","Title: A novel energy-efficient probabilistic routing method for mobile opportunistic networks\nYear: 2018\n\nAbstract: In mobile opportunistic networks (MONs), a large number of intelligent devices carried by moving people can conduct message transmission without the support of communication infrastructures. Routing is one of the concerning and challenging research hotspots in MONs because of nodes’ mobility, intermittent connectivity, limited nodes’ energy, and the dynamic changing quality of the wireless channel. However, only one or several of the above factors are considered in most current routing methods. Moreover, owing to the high mobility of nodes, it is particularly important to decide the time when to make the forwarding decision and which nodes can be selected as the relay nodes. Additionally, due to the dynamic changing quality of the wireless channel, the predetermined relay nodes for the next hop may not receive the message. In this paper, we propose a novel energy-efficient probabilistic routing method for MONs, in which energy and mobility of nodes and the quality of wireless channel are all taken into account. Firstly, we explore the regularity of nodes’ mobility and the encounter probability among nodes to decide the time when to forward messages to other nodes. Secondly, by maintaining the energy fairness among nodes, the network lifetime can be prolonged. Thirdly, by fully taking the dynamic changing quality of the wireless channel into consideration, the retransmission number of messages can be effectively reduced. Additionally, we adopt a forwarding authority transfer policy for each message, which can effectively control the number of replicas for each message. The extensive simulation results show that the proposed method outperforms the existing routing algorithms in terms of the delivery ratio and the overhead ratio.","Title: Efficient and secure auditing scheme for outsourced big data with dynamicity in cloud.\nYear: 2018\n\nAbstract: Big data offers significant benefits; however, security and privacy problems must be considered, especially with regard to outsourced big data. Auditing outsourced big data is an important factor in security and privacy. However, most of the existing auditing techniques are not suitable for outsourced big data due to their high computational and communication costs at the auditor and the data owner (DO) side. In this paper, we propose an efficient auditing scheme for outsourced big data based on algebraic signatures and an XOR-homomorphic function, that can achieve numerous advantages, such as fewer challenges and proofs, non-block verification, data privacy preservation, and lower computational and communication costs. The proposed scheme enables a trusted third-party auditor, on behalf of DOs, to audit the outsourced data in a cloud. Thus, reducing the computational burden on the DOs. Subsequently, we construct a new data structure called a Record Table (RTable) and extend the basic auditing scheme to support the data dynamic operations. As our extended scheme does not use public key encryption, the entire process of updating the data incurs only a small computational and communication overhead with regard to the auditor, the DOs, and the cloud server. Finally, the proposed basic scheme is proved secure under the security model against various attacks. Analysis of the performance shows that both our basic scheme and extended scheme are highly efficient.","Title: Power Allocation Optimization in MC-NOMA Systems for Maximizing Weighted Sum-Rate.\nYear: 2018\n\nAbstract: In this paper, we investigate a power allocation scheme in downlink multi-carrier non-orthogonal multiple access (MC-NOMA) systems for maximizing weighted sum-rate. Taking user-priority into account, we add the weighting factors into the formulated optimization problem. Firstly, we give sufficient and necessary concavity conditions that should be satisfied by the proposed weighted sum-rate maximization problem. Then, for more generally non-concave case, we use a first order approximation to convert the optimization problem and provide an iterative power allocation algorithm to find the globally optimal solution. Simulation results show that our proposed algorithm is superior to orthogonal frequency division multiple access (OFDMA) scheme and average power allocation scheme.","Title: An efficient probabilistic routing scheme based on game theory in opportunistic networks.\nYear: 2019\n\nAbstract: Routing is one of the most challenging problems in opportunistic networks (OppNets) because of the intermittence of the network connection. To address the issue, many routing schemes have been proposed, however, most of them assume that nodes are willing to forward messages for others. In fact, due to limited resources and poor social relations, nodes in OppNets may be selfish and not reluctant to participate in message forwarding. To tackle this issue, in this paper, we propose a Probabilistic Routing scheme based on Game Theory (PRGT) to stimulate cooperation among selfish nodes. Firstly, we introduce virtual money to buy the message for gaining more profits. Then, according to the historical meeting records among different nodes, we establish a Markov-based probability prediction model, in which the message carrier selects a node with higher probability of encountering the destination node as the relay node. Finally, a game theory approach is employed to simulate trading price for message forwarding. The simulation results demonstrate that our proposed routing scheme can effectively improve the delivery rate of messages and reduce network latency.","Title: Radio Resource Allocation Scheme for Drone-Assisted AR Applications\nYear: 2018\n\nAbstract: Mobile edge computing facilitates the implementation of computationally intensive applications on mobile devices, such as Mobile Augmented Reality (MAR). The MAR application usually includes three modules, namely, data collection in the uplink, edge computing and data transmission in the downlink, and the cooperation between the modules will help improve the energy consumption performance of the AR system. We propose an integrated MAR transmission design with companion drones and a high energy efficiency resource allocation scheme. Through a successive convex approximation (SCA) algorithm, we convert non-convex problems into convex ones for optimal solution. Compared with traditional independent offloading by users, joint relay transmission and shared uplink data offloading schemes can produce significant gains in energy efficiency.","Title: Eavesdropping and Jamming Selection Policy for Suspicious UAVs Based on Low Power Consumption over Fading Channels.\nYear: 2019\n\nAbstract: Traditional wireless security focuses on preventing unmanned aerial vehicle (UAV) communications from suspicious eavesdropping and/or jamming attacks. However, there is a growing need for governments to keep malicious UAV communications under legitimate surveillance. This paper first investigates a new surveillance paradigm for monitoring suspicious UAV communications via jamming suspicious UAVs. Due to the power consumption limitation, the choice of eavesdropping and jamming will reflect the performance of the UAVs communication. Therefore, the paper analyses the UAV's eavesdropping and jamming models in different cases, and then proposes the model to optimize the data package in the constraints of lower power consumption, which can be solved by the proposed selection policy. The simulation results validate our proposed selection policy in terms of power consumption and eavesdropped packets. In different fading models, power consumption increases with time, regardless of distances, and our proposed policy performs better in Weibull fading channels in terms of eavesdropped packets.","Title: Improvement of Reflection Detection Success Rate of GNSS RO Measurements Using Artificial Neural Network.\nYear: 2018\n\nAbstract: Global Navigation Satellite System (GNSS) radio occultation (RO) has been widely used in the prediction of weather, climate, and space weather, particularly in the area of tropospheric analyses. However, one of the issues with GNSS RO measurements is that they are interfered with by the signals reflected from the earth's surface. Many RO events are subject to such interfered GNSS measurements, whi...","Title: A location-sensitive over-the-counter medicines recommender based on tensor decomposition\nYear: 2019\n\nAbstract: The last few decades have witnessed a steady increase in medicine prescriptions for the treatment of biometric markers rather than obvious physiological symptoms; especially, the over-the-counter (OTC) medicine experiences rated by patients have huge potential to assist people to make more appropriate decisions. The most existing researches focus on the rating prediction and recommendations in E-commerce field rather than healthcare or medical treatments. In addition, the spatial and temporal factors were not considered in their recommendation mechanisms. Toward this end, this paper propose an efficient OTC medicines recommendation strategy based on tensor decomposition. Considering the impact of regional differentiation, a third-order tensor including medicine, location, and rating is constructed. To inference the usage of a new OTC medicine in a certain location, high-order singular value decomposition is applied to the above tensor for obtaining the intelligent recommendation. In order to evaluate the effectiveness of the proposed approach, we compared the conventional collaborative filtering approach and tensor-based approach in terms of precision and recall. The experimental results demonstrate that our proposed approach is significant better than collaborative filtering approach.","Title: Authentication scheme based on smart card in multi-server environment\nYear: 2020\n\nAbstract: For authentication schemes based on smart card in multi-server environment, there is a common problem—the parameters stored in a user’s smart card linearly increase with the number of the registered servers without involving registration center in helping with authentication process. Therefore, in order to save storage cost and raise efficiency, an authentication scheme based on smart card is proposed in multi-server environment. In the proposed scheme, a user only needs one time registration, and keeps a password to realize the authentication with different servers without involving the registration center in helping with authentication process. The server is unnecessary to store any users information to achieve authentication between the users and the server. Moreover, the security of the proposed scheme is proved by Burrows–Abadi–Needham logic. The security analysis and the performance analysis show the proposed scheme is secured against various well known attacks, and has lower communication cost, computation cost and storage cost compared with several related schemes.","Title: Heuristic Localization Algorithm with a Novel Error Control Mechanism for Wireless Sensor Networks with Few Anchor Nodes.\nYear: 2018\n\nAbstract: A novel iterative localization algorithm with high accuracy and low anchor node dependency for large-scale wireless sensor networks is proposed in this paper. At each iteration, blind nodes are located using a weighted linear least squares-based algorithm. To prevent errors in the blind nodes from propagating and accumulating throughout the network, an anchor geometric feature-based error control mechanism is used to select the nodes that participate in the localization and to estimate the localization confidence. The simulation results show that the algorithm can be used when only a few anchor nodes are involved. This algorithm is more advanced than traditional methods, which often require a large number of well-placed anchor nodes to operate appropriately. By optimizing the decision parameter v of the algorithm, the average localization error of the algorithm is approximately 0.43 meters. When the ratio of anchor nodes (the ratio of the number of anchor nodes to the number of sensor nodes in the network) is 1.25% (i.e., 5 anchor nodes for 400 sensor nodes), the received signal strength indicator (RSSI) variance is 8 dBm, and the radio range is 50 meters. A comparison of the proposed algorithm with global localization methods, including multidimensional scaling (MDS), semidefinite programming (SDP), and shortest-path access (SPA), shows that the proposed algorithm achieves higher location accuracy and stability when the number of anchor nodes is varied. The efficiency of the proposed localization algorithm is evaluated in a real sensor network, and the accuracy is high and robust to radio channel variance.","Title: The Prediction Model of Saccade Target Based on LSTM-CRF for Chinese Reading.\nYear: 2018\n\nAbstract: Through introducing the psychology model of reading cognitive, this paper uses the LSTM neural network and the CRF model respectively to simulate the language cognition process and the eye-movement control process in reading, in order to overcome the defect that the traditional CRF prediction model only considers the context information of the label sequence but can not take into account the context information of the text sequence. First, the psychological process of reading cognition is introduced and the prediction model of saccade target based on LSTM-CRF for Chinese reading is proposed. Then, the experimental data, experimental environment, feature templates and parameter settings needed for model training are introduced. Finally, the conclusion is drawn through experimental comparison: (1) The F1 score of prediction model in saccade labeling based on LSTM-CRF is superior to the traditional CRF prediction model; (2) The predictability of the language itself is an important feature of the saccade target prediction model; (3) The best saccade length for Chinese readers is about 2.5 Chinese characters.","Title: -Hyers-Ulam-Rassias Stability of Semilinear Nonautonomous Impulsive System.\nYear: 2019\n\nAbstract: In this paper, we study a system governed by impulsive semilinear nonautonomous differential equations. We present the beta-Ulam stability, beta-Hyers-Ulam stability and beta-Hyers-Ulam-Rassias stability for the said system on a compact interval and then extended it to an unbounded interval. We use Gronwall type inequality and evolution family as a basic tool for our results. We present an example to demonstrate the application of the main result.","Title: Generalized Spatial Modulation based on Array-Blocks for Millimeter Wave High Speed Railway Communication Systems\nYear: 2018\n\nAbstract: Generalized Spatial Modulation (GSM) technology is a new multiple-input multiple-output (MIMO) technique that can improve spectral efficiency in wireless communication systems. In this paper, a generalized spatial modulation based on array-blocks (AB-GSM) scheme is proposed for the mmWave high speed railway (HSR) communication systems. In the proposed AB-GSM scheme, GSM is adopted at transmitter and more than one array-blocks are simultaneously activated at the base station (BS) to transmit data. Modulated symbols are transmitted by using the radio frequency (RF) beamforming technology. The information bit rate and bit error rate (BER) performance of the AB-GSM system under mmWave channel model are investigated. Theoretical analysis and simulation results show that the proposed AB-GSM scheme has a considerable improvement in the data transmission rate and spectral efficiency compared with the traditional GSM.","Title: Energy-Efficient Power Allocation with Buffer Constraint for High-Speed Railway\nYear: 2018\n\nAbstract: To satisfy the increasing demands for high data-rate service of high-speed railway (HSR) users on the train, the most promising approach is to utilize the two-hop architecture. With this architecture, large amount of data will be transferred to the access point (AP) at which some data may need to be cached when the train approaches the cell edge. In this paper, an energy-efficiency buffer (EEB) power allocation scheme is proposed, which is able to achieve a high energy efficiency under the requirement of buffer size in HSR scenarios. Firstly, the energy-efficiency optimization problem is formulated as a fractional form. Secondly, this non-convex problem is resolved by transforming it into an equivalent one. Then an iterative power allocation algorithm is proposed and the optimal solution is obtained based on it. Finally, we analyze the effect of cache point on energy efficiency (EE) performance of the proposed EEB power allocation scheme. Furthermore, the relationship between the buffer size and EE performance of HSR communication system is presented. Simulation results suggest that the proposed EEB power allocation scheme can achieve the optimal energy-efficient performance.","Title: A Second Order BDF Numerical Scheme with Variable Steps for the Cahn-Hilliard Equation.\nYear: 2019\n\nAbstract: We present and analyze a second order in time variable step BDF2 numerical scheme for the Cahn-Hilliard equation. The construction relies on a second order backward difference, convex-splitting technique and viscous regularizing at the discrete level. We show that the scheme is unconditionally stable and uniquely solvable. In addition, under mild restriction on the ratio of adjacent time-steps, an optimal second order in time convergence rate is established. The proof involves a novel generalized discrete Gronwall-type inequality. As far as we know, this is the first rigorous proof of second order convergence for a variable step BDF2 scheme, even in the linear case, without severe restriction on the ratio of adjacent time-steps. Results of our numerical experiments corroborate our theoretical analysis.","Title: Efficient <tex>$K$</tex>-concern Matching in a Large Graph\nYear: 2018\n\nAbstract: Exact subgraph matching is wildly used for relation exploration in linked data. Existing literatures of matching algorithm focus on exhaustive enumeration of all matches, which are both time and space consuming and even not viable for a large graph. For real world applications such as social search, it is common that not all entities in a query graph are concerned by the users. It is not trivial to find distinct groups of concerned vertices from the exhaustive enumeration of all matches. In this paper, we define the problem of K-concern matching which returns distinct groups of K concerned vertices in all matches. In order to efficiently find K -concern matches in a large graph, we devise a new strategy for the general backtracking algorithm. To minimize the total search space, we propose methods for search order optimization and candidate set pruning. Experiments on real and synthetic datasets show that the query performance of our method exceeds all existing matching algorithms for K-concern matching.","Title: Structure regularized sparse coding for data representation.\nYear: 2019\n\nAbstract: Sparse coding (SC) exhibits impressive performance in many practical applications. However, in the unsupervised scenario, most of the conventional SC methods fail to fully take advantage of the structure of the data. Actually, the structure of the data, especially the global structure that is an implicit prior knowledge, is vital for data analysis. In this paper, we propose a novel method called structure regularized sparse coding (SRSC) for the sparse representation of the data in the unsupervised scenario. In contrast with the other SC methods, a distinct feature of SRSC is that it takes into consideration both the local and global structure of the data and fully exploits the latent category information in the data. By using the local affinity matrix that captures the local structure, we first build a global affinity matrix to encode the global structure of the data. The global affinity matrix fully carries the latent category information that is beneficial to obtain the discriminating representation of the data, Then, we define the optimization model of SRSC and develop a two-step iterative optimization algorithm based on the alternating direction method of multipliers (ADMM) to solve it. The experimental results validate that the proposed method is effective and can achieve better performance over its counterparts.","Title: Design And Experimental Verification On Characteristics Of Valve-Less Piezoelectric Pump Effected By Valve Hole Spacing\nYear: 2019\n\nAbstract: Valve-less piezoelectric pumps possess the advantages of simple structure and absence of electromagnetic interference, which has accordingly drawn widespread attention. In this paper, in order to improve the performance of valve-less piezoelectric pumps, various kinds of the prototypes had been designed and fabricated to discover the relationship between the performance and the structural parameters of valve hole spacing. The prototype is comprised of a piezoelectric actuator and a pump chamber through a conical tube that connects the pump chamber with the buffer chamber. First, the flow characteristics of the valve-less pump were performed by using COMSOL Multiphysics. According to the simulation result, the decline of flow velocity around the valve holes on the side far from the center of the pump chamber may be the reasons for the performance degradation. Second, the effect of valve hole spacing on the prototype was investigated with respect to several parameters, such as the chamber height and cone angle. The experimental results indicated that the valve-less piezoelectric pump output flowrate can be improved by reducing spacing valve hole spacing. A maximum flowrate of 8.43mL/min was achieved at valve hole spacing of 3 mm, which is 13.6% and 47.1% higher than that at 15 mm and 25 mm, respectively. We finally verify the feasibility of improving the capacity of valve-less piezoelectric pumps by reducing valve hole spacing.","Title: A New Type of Eye Movement Model Based on Recurrent Neural Networks for Simulating the Gaze Behavior of Human Reading.\nYear: 2019\n\nAbstract: Traditional eye movement models are based on psychological assumptions and empirical data that are not able to simulate eye movement on previously unseen text data. To address this problem, a new type of eye movement model is presented and tested in this paper. In contrast to conventional psychology-based eye movement models, ours is based on a recurrent neural network (RNN) to generate a gaze point prediction sequence, by using the combination of convolutional neural networks (CNN), bidirectional long short-term memory networks (LSTM), and conditional random fields (CRF). The model uses the eye movement data of a reader reading some texts as training data to predict the eye movements of the same reader reading a previously unseen text. A theoretical analysis of the model is presented to show its excellent convergence performance. Experimental results are then presented to demonstrate that the proposed model can achieve similar prediction accuracy while requiring fewer features than current machine learning models.","Title: Petri net-based methods for analyzing structural security in e-commerce business processes\nYear: 2020\n\nAbstract: The rapid development of e-commerce worldwide, means more e-commerce business processes adopting the structure of multiple participants; these include shopper clients, merchant and third-party payment platforms (TPPs), banks, and so on. It is a distributed and complex system, where communications among these participants rely on the web services and Application Programming Interfaces (APIs) such as Cashier-as-a-Service or CaaS. This introduces new security challenges due to complex interactions among multiple participants, and any design flaws in procedure structures may result in serious security issues. We study the structural security issues based on Petri nets, and a framework for analyzing structural security in e-commerce business process is proposed. Petri net-based modeling and analysis methods are also provided. Given the specifications of e-commerce business processes, the proposed methods can help designers analyze structural security issues of an e-commerce business process.","Title: Stability Of ?-Schemes For Partial Differential Equations With Piecewise Constant Arguments Of Alternately Retarded And Advanced Type\nYear: 2019\n\nAbstract: This paper deals with the analytical and numerical stability of a partial differential equation with piecewise constant arguments of alternately retarded and advanced type. Firstly, the theory of separation of variables in matrix form and the Fourier method are implemented to achieve the sufficient conditions under which the analytic solution is asymptotically stable. Secondly, the discrete equation is obtained by applying the ?-schemes to the original continuous equation, the sufficient conditions for the asymptotic stability of numerical solution are also shown when the mesh ratio satisfying certain conditions. Finally, some numerical experiments for verifying the theoretical results are provided.","Title: A multimedia image edge extraction algorithm based on flexible representation of quantum\nYear: 2019\n\nAbstract: To solve the real-time problem of edge extraction algorithm and improve image edge continuity, an edge extraction algorithm based on quantum flexible representation (flexible representation of Quantum, RFQ) is proposed. First, the image is represented by quantum flexibility, the superposition state of the quantum sequence is used to store all the pixels of the image, and the FRQ image is obtained by the quantum parallel computation which efficiency is greatly improved, secondly, by the translation transformation of the X and Y directions of the FRQ image, the relative quanta of the neighboring pixels of the whole image is obtained. According to the quantum bit to define the quantum black boxUΩ, combining the Sobel operator to compute the Sobel gradient of pixels in order to judge different categories of pixels and extract the edges of the image. The experimental results show that the proposed method has better edge continuity and richer detail edge than the current edge extraction algorithm.","Title: Distributed Finite-Time secondary control for DC Microgrids with Virtual Impedance Arrangement\nYear: 2019\n\nAbstract: In direct current (DC) microgrids, the accurate current sharing could be achieved by regulating the virtual impedance (droop coefficient) and the output voltage average value of each distributed generator (DG) could be restored by regulating the voltage reference value with a secondary controller. However, there is a coupling relationship between the current sharing and the voltage restoration process. In this paper, a distributed finite-time secondary control strategy is proposed aiming at overcoming the coupling effect. The proposed controller consists of four control loops, which are the current sharing controller (CSC), the virtual impedance average value restoration controller (AIRC), the reference voltage consensus controller (RVCC), and the voltage average value restoration controller (AVRC). With the proposed controller, the coupling effect is eliminated and the virtual impedance of each DG is only determined by the system load distribution. Besides, a simplified control strategy is also proposed which only contains the CSC and AIRC, and the reference voltage value can be calculated using the local information. The stability of the proposed controller is analyzed using the Lyapunov method. At last, the proposed controller is simulated in MATLAB/Simulink to verify its effectiveness.","Title: ACNN-FM: A novel recommender with attention-based convolutional neural network and factorization machines\nYear: 2019\n\nAbstract: With the rapid development of the Internet, the data generated from application platforms such as online shopping, e-education, and digital entertainment has exhibited dramatical growth, which has caused serious information overload to Internet users. The traditional recommendation approaches are crucial for Internet users to extract valuable information from various information. However, there exist some problems such as sparse data, cold start, and over-reliance on manual extracted feature and so on. To address the above problems, this paper proposes a novel recommender with Attention-based Convolutional Neural Network and Factorization Machines (ACNN-FM), which achieves the recommendation with comments. Firstly, from the perspective of local to overall, this paper proposes a word-level attention mechanism and a phrase-level attention mechanism to increase the ability to remember the importance and the order of historical vocabulary (phrase) in the process of text processing of convolutional neural networks. Secondly, it constructs a model to automatically extract hidden features of users and items from comments in the form of natural language. Finally, we utilize factorization machines to analyze the association between the hidden features of users and items, and implement the recommendation based on the association. Extensive experiments are conducted for demonstrating that ACNN-FM method outperforms state-of-the-art NARR method, and ACNN-FM has the highest data utilization among NARR, DeepCoNN, BCF and NMF methods, thus the recommendation performance is significantly improved in large-scale data environment.","Title: Efficient Coupling Diffusion of Positive and Negative Information in Online Social Networks\nYear: 2019\n\nAbstract: The increasing popularization of large-scale online social networks (OSNs) facilitates information sharing. Users are able to diffuse positive and negative information independently owing to the high openness of the OSNs. Due to the intervention of user’s emotions and social relationships, the positive and negative information diffusion exhibits a complicated dynamic coupling diffusion process, in which the negative information diffusion can cause social panic and confusion. However, prior works mainly focus on the diffusion of single type of information. To fill this gap, this paper aims to investigate the dynamic diffusion process of the positive and negative information and control the negative information diffusion timely. Specifically, we first establish a coupling diffusion model to characterize the dynamic diffusion process under the coexistence of positive and negative information, then derive the critical condition for the negative information diffusion and certify the stability of the diffusion model. Furthermore, we propose two collaborative control strategies to persuade and guide users to diffuse the positive information simultaneously. Then, the issue of minimizing the total system costs is transformed to an optimal control problem. Finally, we prove the existence and uniqueness of optimal control solutions and obtain the dynamic distribution of optimal control strategies over time to minimize system costs. The experimental results obtained from two real-world datasets verify the effectiveness of our model and the high efficiency of the collaborative control strategies.","Title: Genetic contribution to the phenotypic correlation between trait impulsivity and resting-state functional connectivity of the amygdala and its subregions.\nYear: 2019\n\nAbstract: Trait impulsivity, a predisposition to respond to stimuli without regard for the potentially negative consequences, contributes to many maladaptive behaviors. Studies have shown that both genetic factors and interregional functional interactions underlie trait impulsivity. However, whether common genes contribute to both trait impulsivity and its neural basis is still unknown. This study investigated the phenotypic correlations between trait impulsivity and the resting-state functional connectivity (rsFC) of the amygdala as well as its subregions and the genetic contribution to the phenotypic correlations. By recruiting a sample of 292 twins in late adolescence and young adulthood, we found that trait impulsivity was positively correlated with the rsFC between the left full amygdala and the right dorsolateral prefrontal cortex (DLPFC). Further analyses on the subregions of the amygdala showed that trait impulsivity was positively correlated with the rsFCs between the left basolateral (BL) amygdala and both the right DLPFC and the right inferior frontal gyrus and with the rsFCs between the right superficial (SF) amygdala and both the dorsal anterior cingulate cortex and right anterior insula. Bivariate genetic modelling analyses found genetic overlaps between trait impulsivity and the rsFC of the left full amygdala or the left BL amygdala with the right DLPFC. The proportions of phenotypic associations accounted for by overlapping genes were 82% and 60%, respectively. These results provide evidence for the genetic overlap between trait impulsivity and the intrinsic brain functional connectivity centered at the amygdala and especially at its BL subregion.","Title: Optimal Resource Allocation Via Machine Learning In Coordinated Downlink Multi-Cell Ofdm Networks Under High Mobility\nYear: 2021\n\nAbstract: For a multi-cell OFDM downlink network, a basic problem is to perform resource allocation to maximize the spectral efficiency (SE). Doppler shift, however, leads to a loss of subcarrier orthogonality, resulting in inter-carrier interference (ICI), especially in a high speed environment. In this paper, we solve the resource allocation problem by considering ICI caused by Doppler spread and imperfect channel state information (CSI) caused by estimation errors, quantization errors and feedback delay. However, the resultant resource allocation algorithm is so complicated that it may not be applicable to the wireless communications environment under high mobility since it may change rapidly and therefore needs real-time computation. As such we propose a deep neural network (DNN) approach to approximate the resource allocation algorithm, which greatly reduces the computation time while achieving very good prediction accuracy. Simulation results verify the influence of Doppler shift on the SE performance and the effectiveness of DNNs in terms of computing time.","Title: GNSS-RS Tomography: Retrieval of Tropospheric Water Vapor Fields Using GNSS and RS Observations\nYear: 2022\n\nAbstract: High spatiotemporal resolution atmospheric water vapor can be retrieved using the Global Navigation Satellite System (GNSS) tomography technique, in which the remained ill-posed problem of the tomography system resulting from the acquisition geometry is a vital issue to be addressed. Remote sensing (RS) water vapor data, with high-resolution and global coverage, show great potential for retrieval of slant water vapor (SWV) observations to improve the tomographic geometrical distribution. In this article, we develop a GNSS-RS (GNSS combining RS) tomography model to fully exploit the value of observation signals from GNSS and RS measurements. The two key factors of retrieving the RS SWV are performed by calibrating the original precipitable water vapor (PWV) images and adding the tropospheric horizontal gradients. The results reveal that when introducing the RS SWV observations into the tomography model, the acquisition geometry is significantly improved, with the average rate of voxels crossed by rays from 62% to 95% and the mean number of observation signals from 395 to 508 during the tomographic periods. Independent radiosonde data are used to validate the tomographic water vapor fields. The mean root-mean-square error (RMSE) and bias of the water vapor profiles derived from GNSS-RS solutions are decreased by 28% and 45% with respect to the GNSS-only results, respectively. Such improvements highlight that GNSS-RS troposphere tomography has significant potential to improve the reconstruction of the atmospheric water vapor fields.","Title: Generalization-error-bound-based discriminative dictionary learning\nYear: 2022\n\nAbstract: Support vector guided dictionary learning, as a discriminative dictionary learning method combining with support vector machine (SVM), embodies the margin maximization principle and achieves good generalization performances in many practical applications. However, this method ignores the key fact that the generalization performance of the SVM classifier depends not only on the margin between two classes of training samples, but also on the radius of the smallest sphere covering them. In the paper, we propose a novel method called generalization-error-bound-based discriminative dictionary learning (GEBDDL). The basic insight of GEBDDL is that the coding vectors, which are used to build the SVM classifier, are not fixed during the learning process. As a result, the radius of the smallest sphere changes with the learned coding vectors. The key feature of GEBDDL is that it explicitly incorporates the radius-margin-bound, which is directly related to the upper bound of the leave-one-out error of SVM, into its objective function to guide learning the dictionary and the coding vectors, and building the SVM classifier. In the paper, we first elaborate our motivation and propose the optimization model and then discuss how to solve it in detail. Further, we explore how to approximate the radius of the smallest sphere in our methodology. This can enhance the computational efficiency by bypassing the quadratic programming problem of computing the radius, while yielding a close performance to GEBDDL. Finally, the comprehensive experiments are conducted on several benchmark datasets, and the results demonstrate the superiority of the proposed methods over the other competing methods.","Title: Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based On Minimization Of Exciting Force\nYear: 2021\n\nAbstract: The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors' geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.","Title: Plantar Pressure Detection System Based On Flexible Hydrogel Sensor Array And Wt-Rf\nYear: 2021\n\nAbstract: This paper presents a hydrogel-based flexible sensor array to detect plantar pressure distribution and recognize the gait patterns to assist those who suffer from gait disorders to rehabilitate better. The traditional pressure detection array is composed of rigid metal sensors, which have poor biocompatibility and expensive manufacturing costs. To solve the above problems, we have designed and fabricated a novel flexible sensor array based on AAM/NaCl (Acrylamide/Sodium chloride) hydrogel and PI (Polyimide) membrane. The proposed array exhibits excellent structural flexibility (209 KPa) and high sensitivity (12.3 mV center dot N-1), which allows it to be in full contact with the sole of the foot to collect pressure signals accurately. The Wavelet Transform-Random Forest (WT-RF) algorithm is introduced to recognize the gaits based on the plantar pressure signals. Wavelet transform realizes the signal filtering and normalization, and random forest is responsible for the classification of the processed signals. The classification accuracy of the WT-RF algorithm reaches 91.9%, which ensures the precise recognition of gaits.","Title: Dual Attention Network Based on Knowledge Graph for News Recommendation\nYear: 2021\n\nAbstract: With the continuous development of Internet technology, there are more and more online news readers, and the amount of news is huge and growing explosively. In addition, the news language is highly concentrated and contains a large number of entities. Currently, the commonly used recommendation methods are difficult to make full use of knowledge information and discover the potential interests of users. To solve the above problems, we propose a Dual attention network based on knowledge graph for news recommendation (DAKRec), which takes news titles, the entities contained in them and the contexts as input, and uses knowledge graph to extract news features. In order to better characterize the diversity of users' interests, a dual attention network is constructed to obtain the weight of users' historical news through word-level attention mechanism and item-level attention mechanism (integrating news words, entities, and contexts). Finally, the multi-head attention module is used to connect historical news and candidate news, and the click-through rate is calculated through a fully connected multilayer perceptron after feature fusion. Through a large number of experiments, we prove that our model DAKRec is better than the advanced DKN model and the other comparison models (FM, DMF) in AUC and MSE, further improves the recommendation performance.","Title: A Knowledge Diffusion Model in Autonomous Learning Under Multiple Networks for Personalized Educational Resource Allocation\nYear: 2021\n\nAbstract: Learners’ autonomous learning is at the heart of modern education, and the convenient network brings new opportunities for it. We notice that learners mainly use the combination of online and offline learning methods to complete the entire autonomous learning process, but most of the existing models cannot effectively describe the complex process of knowledge diffusion under the multinetworks fram...","Title: A lightweight and fault-tolerable data aggregation scheme for privacy-friendly smart grids environment\nYear: 2021\n\nAbstract: The smart grid has attracted great attention as a new energy network. The power supplier collects the total consumption data through the smart meter. The data aggregation is a common operation in smart grid. However, the majority of existing data aggregation schemes are based on homomorphic encryption, suffering from heavy computation overhead. Recently, Gope et al. put forward a masking-based data aggregation scheme in smart grid, but there are some security problems by analyzing their scheme. If one of consumption data does not arrive at the aggregator on time, the power supplier will get incorrect aggregation results. To address these issues, we propose a lightweight and fault-tolerable data aggregation scheme. It can determine which smart meters fail to upload data on time with the idea of flag bit, and then power supplier can calculate the masking value of failed smart meter. So the proposed scheme can ensure the correctness of the final aggregation result even if a smart meter fails to upload data. In addition, the proposed scheme can achieve authentication and data collection only using one round of communication interaction while other schemes need more rounds. Security proof shows that the proposed scheme can achieve indistinguishable privacy. Experimental data confirms the efficiency of the proposed scheme.","Title: Flocking of uncertain nonlinear multi-agent systems via distributed adaptive event-triggered control\nYear: 2021\n\nAbstract: This paper investigates flocking problems with uncertain nonlinear multi-agent systems. Two distributed adaptive event-triggered control algorithms are proposed for leaderless and leader-follower flocking, separately. According to Lyapunov stability theory, under the proposed control protocols, we obtain some sufficient conditions to ensure stable flocking motion and maintain connectivity of network topology. And it is proven that there is a positive lower limit of the interval between any two trigger events, which indicates that the Zeno behavior will not occur. As a result, communication bandwidth resources are effectively saved on the premise of stable flocking. Lastly, numerical simulations are presented to verify the availability of the theoretical results.","Title: Fairness-Aware Power Allocation In Downlink Mimo-Noma Systems\nYear: 2021\n\nAbstract: Non-orthogonal multiple access (NOMA) has attracted great attention due to its potential of providing high spectral efficiency and massive connectivity. Combining it with multiple-input multiple-output (MIMO) technology can further improve the spectrum efficiency. In this paper, the power allocation problem in downlink multi-cluster MIMO-NOMA systems is investigated for maximizing the fairness utility function. First, a long-term fairness function is considered and the optimization problem is formulated as a weighted sum-rate maximization problem. The problem is transformed into a convex form by introducing two sets of auxiliary variables, and propose an iterative algorithm to update the weight factors and the auxiliary variables. Then, an instantaneous fairness is considered and the optimization problem is formulated as a minimum data-rate maximization problem. It is transfiormed into a one-dimensional optimization problem based on an iterative algorithm and a closed-form power allocation expression is deduced. Simulation results illustrate that the proposed two fairness power allocation schemes have better performance of edge-user rate than the comparable schemes.","Title: Svm-Based Online Learning For Interference-Aware Multi-Cell Mmwave Vehicular Communications\nYear: 2021\n\nAbstract: This paper proposes a data-driven method of mmWave beam selection in multi-cell systems to achieve a near-optimal fast beam allocation with low complexity. In particular, an online learning algorithm based on support vector machine (SVM) equipped with the radial basis function kernel, namely SVM-based online beam selection (SBOS) algorithm is proposed. The proposed algorithm starts with an adaptive beam selection process for certain traffic pattern that uses an SVM learning model to adaptively refine the beam selection strategy. Specifically, SVM-based model labels the feedback (the average information rate) from the cellular system, then learns from samples, and makes the scheme space smaller by maximising samples' minimum distances to all labelled samples in the sample space constrained by newly learned boundaries. Then, according to the aggregated data about the traffic patterns and the performance of corresponding beam selection strategy, SBOS algorithm exploits beam selection schemes recorded in the database or explores new schemes for unknown situations, respectively, and how to tune the hyperparameters for the SBOS algorithm is discussed. Furthermore, the extensive simulation results show that the proposed algorithm achieves a better performance versus upper confidence bound and Random methods.","Title: Pricing for Using Operator Platforms with Sharing Edge Services\nYear: 2021\n\nAbstract: This paper explores the influence of competition between sharing edge service platforms. In particular, each server node in the edge network is regarded as an edge service provider(ESP). Each mobile device that needs to get edge services is considered as a user. There are two operators in the network, each of them offering a platform that contains several ESPs. Both platforms compete for users by ...","Title: A secure cross-domain authentication scheme with perfect forward security and complete anonymity in fog computing\nYear: 2021\n\nAbstract: Nowadays, fog computing has become an emerging hot-topic for possessing the same advantages as cloud computing and the lower latency. Nevertheless, there are still many issues in fog computing that worth studying, the most importantly of which are key agreement and user authentication. In order to achieve secure communication among different entities, designing a secure key agreement and user authentication scheme becomes an urgent issue. Although many schemes have been investigated the key agreement and user authentication for cloud computing, these schemes cannot be directly applied to the fog computing due to efficiency and cost. To tackle this problem, we propose a secure and efficient key agreement and user authentication scheme for fog computing. Our scheme can establish secure sessions among different entities, and users can achieve cross-domain access to other fog server. Most importantly, Our scheme satisfies the perfect forward security and the complete anonymity. We prove that our scheme is secure in the random oracle model, and achieve formal security verification through the AVISPA tool. Finally, the performance analysis demonstrates that our scheme tends to be more efficient in comparison with similar schemes.","Title: Deep Learning-Based Signal Detection with Soft Information for MISO-NOMA Systems\nYear: 2021\n\nAbstract: This paper proposes a deep learning-based receiver scheme with soft information for uplink multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) systems, named by DLSI. In the proposed DLSI, we first perform QL-decomposition for channel matrix and iteratively construct the solution of the objective function for signal detection. Then deep neural networks (DNNs) are used to realize iteration steps and restore the symbols of the transmitted signals one by one. After all symbols of a user are detected, the successive interference cancellation (SIC) algorithm is used to detect the symbols of the next user. The output of each DNN is added with a soft decision layer, and the soft information will be input to the next DNN to improve the accuracy of training. Soft information contains more signal knowledge than hard decision, so it is also used in the SIC step, which reduces error propagation to a certain extent. Simulation results show that the performance of the DLSI is better than other deep learning methods.","Title: HALT study on smart electricity meter\nYear: 2017\n\nAbstract: Smart electricity meters (SEMs) play a very important role in our life, and their reliability has been increasingly emphasized by users, developers and manufacturers. To improve the reliability of SEMs, SEM enterprises have conducted a lots of activities related to reliability design, process control and test, etc. of SEMs; however, affected by many reasons, such as defects caused by raw materials, components and manufacturing process, and relatively extreme operating environment, SEMs are hard to achieve inherent reliability level of the original design. To meet the requirements for the time to market, performance of SEMs are required to be evaluated in the shortest time. The Highly Accelerated Life Test (HALT) has been widely used to obtain more reliability information in a short time by stimulating potential defects of products and shortening test duration, and now has become an important mean to evaluate product reliability. Therefore, HALT is an effective way to evaluate performance of SEMs, and the experimental method has been fully approved, promoted and widely used by SEM manufacturers at home and abroad. However, there is no unified HALT program for SEMs. The paper introduces research status of HALT on SEMs, the significance of HALT to improve the product reliability, terms and definitions related to HALT on SEMs, and provides detailed discussion on the way to carry out HALT experiment, including preparation, specification indexes of experiment parameters, requirements for capacity of experimental equipment, experimental steps and details; it has provided theoretical basis and operation guidance for HALT on SEMs. Finally, we conduct an HALT example according to the test methods to show that the poweron and meter reading item is the weakest part of SEM.","Title: Weighted Mean Temperature Modelling Using Regional Radiosonde Observations for the Yangtze River Delta Region in China\nYear: 2022\n\nAbstract: Precipitable water vapor can be estimated from the Global Navigation Satellite System (GNSS) signal's zenith wet delay (ZWD) by multiplying a conversion factor, which is a function of weighted mean temperature (T-m) over the GNSS station. Obtaining T-m is an important step in GNSS precipitable water vapor (PWV) conversion. In this study, aiming at the problem that T-m is affected by space and time, observations from seven radiosonde stations in the Yangtze River Delta region of China during 2015-2016 were used to establish both linear and nonlinear multifactor regional T-m model (RTM). Compared with the Bevis model, the results showed that the bias of yearly one-factor RTM, two-factor RTM and three-factor RTM was reduced by 0.55 K, 0.68 K and 0.69 K, respectively. Meanwhile, the RMSE of yearly one-factor, two-factor and three-factor RTM was reduced by 0.56 K, 0.80 K and 0.83 K, respectively. Compared with the yearly three-factor linear RTM, the mean bias and RMSE of the linear seasonal three-factor RTMs decreased by 0.06 K and 0.10 K, respectively. The precision of nonlinear seasonal three-factor RTMs is comparable to linear seasonal three-factor RTMs, but the expressions of the linear RTMs are easier to use. Therefore, linear seasonal three-factor RTMs are more suitable for calculating T-m and are recommended to use for PWV conversion in the Yangtze River Delta region.","Title: Data-Driven Congestion Control of Micro Smart Sensor Networks for Transparent Substations\nYear: 2021\n\nAbstract: Micro smart sensors and sensor networks are the key bases for building a fully visible, perceptible and controllable transparent substation in power grid. However, the massive deployment of micro smart sensors often leads to network congestion and directly affects the quality of information transmission. In practice, control design for micro sensor networks is often disturbed by factors such as nonlinearity, time delay and time-varying parameters, and the mathematical model is inaccurate. To solve these problems, this paper proposes a Koopman operator based data-driven congestion control scheme without using any system model information, based on model predictive control (MPC) and extended state observer (ESO). Firstly, according to the Koopman operator theory, a data-driven linear Koopman model for micro smart sensor networks is derived, only using the input/output data. Then an ESO based MPC scheme is designed to obtain the optimal packet dropping probability in the micro smart sensor node buffer area. Specifically, ESO performs real-time online estimation of the modeling errors, such as time-varying parameters, time delay and the external disturbances. Then the estimated modeling errors are viewed as total disturbances and are compensated in MPC, so that the queue length in the node buffer can quickly stabilize at the set value. Extensive simulations are conducted to verify the accuracy of Koopman model, and the effectiveness of the proposed control system design.","Title: Design and Research of Symmetrical Multi-Throttle Thrust Hydrostatic Bearing Based on Comparative Analysis of Various Meshes\nYear: 2022\n\nAbstract: Due to the advantages of high rotation accuracy and long life, hydrostatic air bearings are widely used in precision rotation equipment, such as machine tools and turntables. It is imperative to reasonably design the structural size of the bearing, especially as the size of the bearing in the precision turntable determines the bearing capacity of the turntable. At present, commercial CFD software is used chiefly for simulation verification for the design of air bearings. The mesh divided in the simulation calculation has a significant impact on the efficiency of the calculation and determines the accuracy of the final simulation results. Therefore, this paper takes the symmetrical multi-throttle thrust bearing in the precision turntable as the research object and compares and studies the advantages and disadvantages of sliced structured meshes, continuous structured meshes, and unstructured meshes. On this basis, simulation analysis of bearing capacity for different radial equalizing groove lengths, widths, and depths and explores the influence of the structure size of the thrust bearing on its bearing capacity. The study shows that the length and depth of the throttle groove significantly influence the bearing capacity, while the width has little influence on the bearing capacity. Therefore, under the specific cavity volume to ensure the dynamic characteristics of the bearing, the width of the throttling groove should be reduced first, and the length and depth of the throttling groove should be increased to improve the bearing capacity.","Title: A New Cumulative Anomaly-Based Model for the Detection of Heavy Precipitation Using GNSS-Derived Tropospheric Products\nYear: 2022\n\nAbstract: In recent years, tropospheric products obtained from ground-based global navigation satellite system (GNSS) measurements, especially the zenith total delay (ZTD) and precipitable water vapor (PWV) estimates, have advanced their usages in meteorological applications such as the detection of precipitation events. Generally, a cumulative anomaly (CA) time series of any atmospheric variable, which represents the long-term departure of the variable from its & x201C;normal & x201D; cycle, is widely used for quantitatively estimating the variable & x2019;s variations in response to a weather event. In this study, a new cumulative anomaly-based model (NCAM) containing 14 variables, including not only PWV and ZTD values but also their respective six types of derivatives, for detecting heavy precipitation was developed. The 6-h CA time series of the variables were calculated based on the data of hourly precipitation records and time series of ZTD and PWV collected at the co-located HKSC & x2013;King & x2019;s Park (KP) stations over the eight-year period 2010 & x2013;2017. The model was evaluated using the 14 variables & x2019; CA time series to detect heavy precipitation events happened in the summer months over the period 2018 & x2013;2019, and precipitation records in the same period were used as the reference. Results demonstrated that 99.1 & x0025; of heavy precipitation was correctly detected by the NCAM with a lead time of 2.87 h, and the false alarm ratio (FAR) score resulting from the model was reduced to 22.4 & x0025;. In addition, two case studies were also conducted to verify the effectiveness of the NCAM. These results all provide a promising direction for the application of using the CA time series of GNSS tropospheric products to the detection of heavy precipitation events.","Title: An Exergoeconomic Analysis of a Gas-Type Industrial Drying System of Black Tea\nYear: 2022\n\nAbstract: The performance evaluation and optimization of an energy conversion system design of an energy intensive drying system applied the method of combining exergy and economy is a theme of global concern. In this study, a gas-type industrial drying system of black tea with a capacity of 100 kg/h is used to investigate the exergetic and economic performance through the exergy and exergoeconomic methodology. The result shows that the drying rate of tea varies from the maximum value of 3.48 g(water)/g(dry matter) h to the minimum 0.18 g(water)/g(dry matter) h. The highest exergy destruction rate is found for the drying chamber (74.92 kW), followed by the combustion chamber (20.42 kW) in the initial drying system, and 51.83 kW and 21.15 kW in the redrying system. Similarly, the highest cost of the exergy destruction rate is found for the drying chamber (18.497 USD/h), followed by the combustion chamber (5.041 USD/h) in the initial drying system, and 12.796 USD/h and 5.222 USD/h in the redrying system. Furthermore, we analyzed the unit exergy rate consumed and the unit exergy cost of water removal in different drying sections of the drying system, and determined the optimal ordering of each component. These results mentioned above indicate that, whether from an energy or economic perspective, the component improvements should prioritize the drying chamber. Accordingly, minimizing exergy destruction and the cost of the exergy destruction rate can be considered as a strategy for improving the performance of energy and economy. Overall, the main results provide a more intuitive judgment for system improvement and optimization, and the exergy and exergoeconomic methodology can be commended as a method for agricultural product industrial drying from the perspective of exergoeconomics.","Title: A Positivity Preserving, Energy Stable Finite Difference Scheme for the Flory-Huggins-Cahn-Hilliard-Navier-Stokes System\nYear: 2022\n\nAbstract: In this paper, we propose and analyze a finite difference numerical scheme for the Cahn-Hilliard-Navier-Stokes system, with logarithmic Flory-Huggins energy potential. In the numerical approximation to the singular chemical potential, the logarithmic term and the surface diffusion term are implicitly updated, while an explicit computation is applied to the concave expansive term. Moreover, the convective term in the phase field evolutionary equation is approximated in a semi-implicit manner. Similarly, the fluid momentum equation is computed by a semi-implicit algorithm: implicit treatment for the kinematic diffusion term, explicit update for the pressure gradient, combined with semi-implicit approximations to the fluid convection and the phase field coupled term, respectively. Such a semi-implicit method gives an intermediate velocity field. Subsequently, a Helmholtz projection into the divergence-free vector field yields the velocity vector and the pressure variable at the next time step. This approach decouples the Stokes solver, which in turn drastically improves the numerical efficiency. The positivity-preserving property and the unique solvability of the proposed numerical scheme is theoretically justified, i.e., the phase variable is always between -1 and 1, following the singular nature of the logarithmic term as the phase variable approaches the singular limit values. In addition, an iteration construction technique is applied in the positivity-preserving and unique solvability analysis, motivated by the non-symmetric nature of the fluid convection term. The energy stability of the proposed numerical scheme could be derived by a careful estimate. A few numerical results are presented to validate the robustness of the proposed numerical scheme.","Title: MFPSE: Multi-user Forward Private Searchable Encryption with dynamic authorization in cloud computing\nYear: 2022\n\nAbstract: Dynamic Searchable Symmetric Encryption (DSSE) allows users to outsource data with ciphertext format to untrusted servers and supports the operations of data adding and deleting, which is adopted in common usage by government and business. Recently, the primitive of Forward Privacy in DSSE has drawn great public interest owing to its beneficial feature, which is that it can guard against the newly uploaded files from linking to previous search tokens. However, most of existing Forward Private Searchable Encryption (FPSE) schemes focus on single-user environment, which means that only the users themselves can utilize the data, greatly limits the wide application in cloud computing. To our knowledge, it is difficult to migrate the FPSE schemes to multi-user network. First, to realize forward privacy, the data owner should share the entire key group to the legitimate users, which means the users have the privilege of tampering or deleting data rather than query only; secondly, some FPSE schemes use the special structures and cannot be directly developed to multi-user network. Inspired by this, we present a scheme of multi-user forward private searchable encryption with dynamic authorization. The proposed scheme is based on a new structure of Multi-user State Chain and involves dynamic keyword-oriented authorization management. We prove our scheme can meet the secure characteristics, then conduct the performance evaluation and experiments. The results demonstrate that compared with the existing solutions, our scheme is superior in efficiency and practicability.","Title: Temporal-Spatial Collaborative Mobile Edge Caching With User Satisfaction Awareness\nYear: 2022\n\nAbstract: For mobile proactive edge caching problems, the hit action cannot always reflect the efficiency of the cache strategy unilaterally. Thus, the satisfaction information of users should be used to improve the intelligent cache strategy. Motivated by this, this paper focuses a caching scheme that jointly considers the cache evaluation both from the perspectives of the hit action and satisfaction of users (Algorithm 3). Accordingly, we first propose a requesting behavior prediction model (Algorithm 1) to handle the multiple content features. Then, a requesting behavior factor learning algorithm (Algorithm 2) based on the online gradient descent (OGD) with regulations is proposed to obtain the estimation of the parameters of the model in Algorithm 1. Further, the probabilistic tensor factorization learning (PTFL) model with collaborative filtering and Markov Chain Monte Carlo (MCMC) procedure are introduced for the learning process. Finally, the proposed the caching Algorithm 3 based on the hit action prediction and the collaborative temporal-spatial satisfaction learning scheme can be performed. Moreover, we theoretically combine the upper limit performance of user request prediction errors with the lower limit of user satisfaction of edge cache. The experimental results verify the effectiveness of the proposed algorithm.","Title: A Comprehensive Study on Factors Affecting the Calibration of Potential Evapotranspiration Derived from the Thornthwaite Model\nYear: 2022\n\nAbstract: Potential evapotranspiration (PET) is generally estimated using empirical models; thus, how to improve PET estimation accuracy has received widespread attention in recent years. Among all the models, although the temperature-driven Thornthwaite (TH) model is easy to operate, its estimation accuracy is rather limited. Although previous researchers proved that the accuracy of TH-PET can be greatly improved by using a limited number of variables to conduct calibration exercises, only preliminary experiments were conducted. In this study, to refine this innovation practice, we comprehensively investigated the factors that affect the calibration performances, including the selection of variables, seasonal effects, and spatial distribution of Global Navigation Satellite System (GNSS)/weather stations. By analyzing the factors and their effects, the following conclusions have been drawn: (1) an optimal variable selection scheme containing zenith total delay, temperature, pressure, and mean Julian Date was proposed; (2) the most salient improvements are in the winter and summer seasons, with improvement rates over 80%; (3) with the changes in horizontal (2.771-44.723 km) and height (1.239-344.665 m) differences among ten pairs of GNSS/weather stations, there are no obvious differences in the performances. These findings can offer an in-depth understanding of this practice and provide technical references to future applications.","Title: An Improved Method for Rainfall Forecast Based on GNSS-PWV\nYear: 2022\n\nAbstract: Global navigation satellite systems (GNSS) has been applied to the sounding of precipitable water vapor (PWV) due to its high accuracy and high spatiotemporal resolutions. PWV obtained from GNSS (GNSS-PWV) can be used to investigate extreme weather phenomena, such as the formation mechanism and prediction of rainfalls. In the study, a new, improved model for rainfall forecasting was developed based on GNSS data and rainfall data for the 9-year period from 2010 to 2018 at 66 stations located in the USA. The new model included three prediction factors-PWV value, PWV increase, maximum hourly PWV increase. The two key tasks involved for the development of the model were the determination of the thresholds for each prediction factor and the selection of the optimal strategy for using the three prediction factors together. For determining the thresholds, both critical success index (CSI) and true skill statistic (TSS) were tested, and results showed that TSS outperformed CSI for all rainfall events tested. Then, various strategies by combining the three prediction factors together were also tested, and results indicated that the best forecast result was from the case that any two of the prediction factors were over their own thresholds. Finally, the new model was evaluated using the GNSS data for the 2-year period from 2019 to 2020 at the above mentioned 66 stations, and the probability of detection (POD) and false-alarms rate (FAR) were adopted to measure the model performances. Over the 66 stations, the POD values ranged from 73% to 97% with the mean of 87%, and the FARs ranged from 26% to 77% with the mean of 53%. Moreover, it was also found that both POD and FAR values were related to the region of the station; e.g., the results at the stations that are located in humid regions were better than the ones located in dry regions. All these results suggest the feasibility and good performance of using GNSS-PWV for forecasting rainfall.","Title: On Influencing Factors in Metaphor Variation for Five Elements Translation in TCM: A Binomial Logistic Regression Analysis\nYear: 2022\n\nAbstract: Metaphor variation for English translations of Five Elements will impair the effect of Traditional Chinese Medicine (TCM) international communication. Few studies focus on contributing factors in metaphor variants for Five Elements translations. We model the binary designations for the Five-Element metaphor variants to analyze the internal and external language factors affecting the choice of ontological and structural metaphor, with the data from a corpus of six translations of the Inner Canon of Yellow Emperor. Statistical results unveil that the clause type, the syntax of Causer, language varieties, and the interaction of the clause type and language varieties significantly influence the metaphor variants. The complex interplay of the clause type and language varieties can explain people's cognitive differences in conceptualizing five elements. The study sheds light on the research of the Five Elements translation from the view of Construction Grammar and shows the benefit of machine learning technology for quantitatively describing and explaining the metaphor variation. It may hopefully uncover translators' cognitive mechanisms and pave a new way for TCM translation studies."],"string":"[\n \"Title: Robin–Robin domain decomposition methods for the steady-state Stokes–Darcy system with the Beavers–Joseph interface condition\\nYear: 2011\\n\\nAbstract: Domain decomposition methods for solving the coupled Stokes–Darcy system with the Beavers–Joseph interface condition are proposed and analyzed. Robin boundary conditions are used to decouple the Stokes and Darcy parts of the system. Then, parallel and serial domain decomposition methods are constructed based on the two decoupled sub-problems. Convergence of the two methods is demonstrated and the results of computational experiments are presented to illustrate the convergence.\",\n \"Title: Node Aggregation Degree-Aware Random Routing For Non-Uniform Wireless Sensor Networks\\nYear: 2011\\n\\nAbstract: Routing is still a challenging issue for wireless sensor networks (WSNs), in particular for WSNs with a non-uniform deployment of nodes. This paper introduces a Node Aggregation Degree-aware Random Routing (NADRR) algorithm for non-uniform WSNs with the help of two new concepts, namely the Local Vertical Aggregation Degree (LVAD) and Local Horizontal Aggregation Degree (LHAD). Our basic idea is to first apply the LVAD and LHAD to determine one size-proper forwarding region (rather than a fixed-size one as in uniform node deployment case) for each node participating in routing, then select the next hop node from the size-proper forwarding region in a probabilistic way, considering both the residual energy and distribution of nodes. In this way, a good adaptability to the non-uniform deployment of nodes can be guaranteed by the new routing algorithm. Extensive simulation results show that in comparison with other classical geographic position based routing algorithms, such as GPSR, TPGF and CR, the proposed NADRR algorithm can result in lower node energy consumption, better balance of node energy consumption, higher routing success rate and longer network lifetime.\",\n \"Title: A Random Key Management Scheme for Wireless Sensor Networks\\nYear: 2008\\n\\nAbstract: The establishment of shared keys between communicating neighbor nodes in wireless sensor networks is a challenge due to resource-constrained sensor networks. Several key pre-distribution schemes have been proposed in literatures to establish pairwise keys between sensor nodes. However, many of them are either too complicated to fit for wireless sensor networks or insecure for some common aggressions. In this paper, we propose a random key management scheme based on random key pre-distribution for wireless sensor networks. To achieve better performance and security, the proposed scheme employs two different phases to establish enhanced pairwise keys between neighboring nodes. Compared with other existing random key pre-distribution schemes, our scheme has better resilience against node capture and also performs better in terms of network connectivity and scalability with appropriate memory, computation and communication overheads.\",\n \"Title: Access control scheme with tracing for outsourced databases.\\nYear: 2012\\n\\nAbstract: To manage dynamic access control and deter pirate attacks on outsourced databases, a dynamic access control scheme with tracing is proposed. In our scheme, we introduce the traitor tracing idea into outsource databases, and employ a polynomial function and filter function as the basic means of constructing encryption and decryption procedures to reduce computation, communication, and storage overheads. Compared to previous access control schemes for outsourced databases, our scheme can not only protect sensitive data from leaking and perform scalable encryption at the server side without shipping the outsourced data back to the data owner when group membership is changed, but also provide trace-and-revoke features. When malicious users clone and sell their decryption keys for profit, our scheme can trace the decryption keys to the malicious users and revoke them. Furthermore, our scheme avoids massive message exchanges for establishing the decryption key between the data owner and the user. Compared to previously proposed publickey traitor tracing schemes, our scheme can simultaneously achieve full collusion resistance, full recoverability, full revocation, and black-box traceability. The proof of security and analysis of performance show that our scheme is secure and efficient. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.\",\n \"Title: An intelligent software-integrated environment of IC test\\nYear: 1994\\n\\nAbstract: The migration and simulation of IC test programs among the heterogeneous ATE systems are a very difficult task. An unifying IC test software-integrated environment from simulation to test for digital circuit has been developed. The environment, TeDS which is designed by using object-oriented paradigm, supports two kinds of CAD systems and three kinds of ATE (Automatic Test Equipment). The paper focuses on issues and techniques in developing TeDS based on object-oriented paradigm\",\n \"Title: On time granularity and event granularity in simulation service composition (WIP)\\nYear: 2012\\n\\nAbstract: There is an increasing need for systematic composition of simulation services in the emerging service-oriented computing environment. An important issue that hinders simulation service composition is the mismatch of granularity when coupling two services together. In this paper, we focus on time granularity and event granularity in composing simulation services at the pragmatic level. We identify and develop four types of granularity handling agents to be associated with the couplings between services. The developed method is illustrated by a coupled weather-wildfire simulation example.\",\n \"Title: EiSIRS: a formal model to analyze the dynamics of worm propagation in wireless sensor networks\\nYear: 2010\\n\\nAbstract: Based on the epidemic theory, this paper proposes a novel model for analyzing the dynamics of worm propagation in Wireless\\n Sensor Networks (WSNs). The proposed model supports the sleep and work interleaving schedule policy for sensor nodes, and\\n it can also describe the process of multi-worm propagation in WSNs. In addition, a necessary condition for worms to spread\\n in WSNs is derived, which may be useful in designing a secure WSN. Simulation results show that the process of worm propagation\\n in WSNs is sensitive to the energy consumption of nodes and the sleep and work interleaving schedule policy for nodes. Therefore,\\n this paper provides new insights for the dynamics of worm propagation in WSNs.\",\n \"Title: Path Reconstruction Based On Natural Language And The Uncertainty Problems\\nYear: 2004\\n\\nAbstract: It is an important research issue to build systems supporting natural language comprehension in social geographic information service. In this paper, representation of a path in natural language (NLRP) is discussed. Based on the syntax model of NLRP, an algorithm named PRA (path reconstruction algorithm) used for generating linear path according to the reference map and NLRP expression is described. Inevitably, a NLRP expression contains some uncertainties, which mainly come from the spatial cognition process and imprecise expression. The uncertainties of NLRP include uncertainties of direction, distance and topologic relationship. They make the NLRP expression ambiguous and bring some problems to PRA. The solution is also discussed.\",\n \"Title: On Node Isolation Under Churn in Unstructured P2P Networks with Heavy-Tailed Lifetimes\\nYear: 2007\\n\\nAbstract: Previous analytical studies [12], [18] of unstructured P2P resilience have assumed exponential user lifetimes and only considered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-selection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared to uniform selection of neighbors. In fact, the second strategy based on random walks on age-weighted graphs demonstrates that for lifetimes with infinite variance, the system monotonically increases its resilience as its age and size grow. Specifically, we show that the probability of isolation converges to zero as these two metrics tend to infinity. We finish the paper with simulations in finite-size graphs that demonstrate the effect of this result in practice.\",\n \"Title: Residual-based estimation of peer and link lifetimes in P2P networks\\nYear: 2009\\n\\nAbstract: Existing methods of measuring lifetimes in P2P systems usually rely on the so-called Create-Based Method (CBM), which divides a given observation window into two halves and samples users \\\"created\\\" in the first half every Δ time units until they die or the observation period ends. Despite its frequent use, this approach has no rigorous accuracy or overhead analysis in the literature. To shed more light on its performance, we first derive a model for CBM and show that small window size or large Δ may lead to highly inaccurate lifetime distributions. We then show that create-based sampling exhibits an inherent tradeoff between overhead and accuracy, which does not allow any fundamental improvement to the method. Instead, we propose a completely different approach for sampling user dynamics that keeps track of only residual lifetimes of peers and uses a simple renewal-process model to recover the actual lifetimes from the observed residuals. Our analysis indicates that for reasonably large systems, the proposed method can reduce bandwidth consumption by several orders of magnitude compared to prior approaches while simultaneously achieving higher accuracy. We finish the paper by implementing a two-tier Gnutella network crawler equipped with the proposed sampling method and obtain the distribution of ultrapeer lifetimes in a network of 6.4 million users and 60 million links. Our experimental results show that ultrapeer lifetimes are Pareto with shape α ≅ 1.1; however, link lifetimes exhibit much lighter tails with α ≅ 1.8.\",\n \"Title: Linear combination test for gene set analysis of a continuous phenotype.\\nYear: 2013\\n\\nAbstract: Gene set analysis (GSA) methods test the association of sets of genes with a phenotype in gene expression microarray studies. Many GSA methods have been proposed, especially methods for use with a binary phenotype. Equally, if not more importantly however, is the ability to test the enrichment of a gene signature or pathway against the continuous phenotypes which are routinely and commonly observed in, for example, clinicopathological measurements. It is not always easy or meaningful to dichotomize continuous phenotypes into two classes, and attempting to do this may lead to the inaccurate classification of samples, which would affect the downstream enrichment analysis. In the present study, we have build on recent efforts to incorporate correlation structure within gene sets and pathways into the GSA test statistic. To address the issue of continuous phenotypes directly without the need for artificial discrete classification and thus increase the power of the test while ensuring computational efficiency and rigor, new GSA methods that can incorporate a covariance matrix estimator for a continuous phenotype may present an effective approach.We have designed a new method by extending the GSA approach called Linear Combination Test (LCT) from a binary to a continuous phenotype. Simulation studies and a real microarray dataset were used to compare the proposed LCT for a continuous phenotype, a modification of LCT (referred to as LCT2), and two publicly available GSA methods for continuous phenotypes.We found that the LCT methods performed better than the other two GSA methods; however, this finding should be understood in the context of our specific simulation studies and the real microarray dataset that were used to compare the methods. Free R-codes to perform LCT for binary and continuous phenotypes are available at http://www.ualberta.ca/~yyasui/homepage.html. The R-code to perform LCT for a continuous phenotype is available as Additional file 1.\",\n \"Title: Ant Colony Optimization-Based Location-Aware Routing for Wireless Sensor Networks\\nYear: 2008\\n\\nAbstract: The routing for Wireless Sensor Networks (WSNs) is a key and hard problem, and it is a research topic in the field of WSN applications. Based on Ant Colony Optimization (ACO), this paper proposes a novel adaptive intelligent routing scheme for WSNs. Following the proposed scheme, a high performance routing algorithm for WSNs is designed. The proposed routing scheme is very different from the existing ACO based routing schema for WSNs. On one hand, in the proposed scheme, the search range for an ant to select its next-hop node is limited to a subset of the set of the neighbors of the current node. On the other hand, by fusing the residual energy and the global and local location information of nodes, the new probability transition rules for an ant to select its next-hop node are defined. Compared with other ACO based routing algorithms for WSNs, the proposed routing algorithm has a better network performance on aspects of energy consumption, energy efficiency, and packet delivery latency.\",\n \"Title: Efficient and Long-Time Accurate Second-Order Methods for the Stokes-Darcy System.\\nYear: 2013\\n\\nAbstract: We propose and study two second-order in time implicit-explicit methods for the coupled Stokes-Darcy system that governs flows in karst aquifers and other subsurface flow systems. The first method is a combination of a second-order backward differentiation formula and the second-order Gear's extrapolation approach. The second is a combination of the second-order Adams-Moulton and second-order Adams-Bashforth methods. Both algorithms only require the solution of decoupled Stokes and Darcy problems at each time-step. Hence, these schemes are very efficient and can be easily implemented using legacy codes. We establish the unconditional and uniform in time stability for both schemes. The uniform in time stability leads to uniform in time control of the error which is highly desirable for modeling physical processes, e.g., contaminant sequestration and release, that occur over very long time scales. Error estimates for fully discretized schemes using finite element spatial discretizations are derived. Numerical examples are provided that illustrate the accuracy, efficiency, and long-time stability of the two schemes.\",\n \"Title: Threshold Proxy Signature Scheme with Strong Real-Time Efficiency\\nYear: 2008\\n\\nAbstract: The threshold proxy signature scheme with strong real-time efficiency is proposed based on a trapdoor hash function and the sharing secret technology. In the scheme, the procedure of generating threshold proxy signature is performed in two phases. The off-line phase generates a threshold proxy pre-signature before the message to be signed is even known. The pre-signature is independent of the particular message to be signed and is stored for future in the on-line phase. While on-line phase generates quickly a threshold proxy signature using the pre-signature once the message to be signed is presented. The on-line phase is typically very fast and strong real-time efficiency since it only needs a few modular additions and multiplications and one round of communication among proxy signers. Furthermore, the scheme not only has strong real-time efficiency, but also withstands the conspiracy attack existed in the previous schemes and requires no trusted third party. The scheme is particularly useful for requiring the strong real-time efficiency and fully distributed networks such as electric wallet or smart cards etc.\",\n \"Title: Construction of Anti-Collusion Codes Based on Cover-Free Families\\nYear: 2009\\n\\nAbstract: Digital fingerprinting is a technique for identifying users who use multimedia content for unintended purpose, such as redistribution. In order to characterize the fingerprints that can withstand collusion attack, Dittmann et. al proposed the definition of anti-collusion codes (ACCs). In this paper, we present a new approach to construct anti-collusion codes based on cover-free families. All the previous constructions of ACCs are special cases of our construction. Especially, we can construct ACCs by using error-correcting codes. Collusion resistance comparison of different schemes show that our scheme is more efficient than previous ACCs. Some related problems on this subject are proposed.\",\n \"Title: Translational integrity and continuity: personalized biomedical data integration.\\nYear: 2009\\n\\nAbstract: Translational research data are generated in multiple research domains from the bedside to experimental laboratories. These data are typically stored in heterogeneous databases, held by segregated research domains, and described with inconsistent terminologies. Such inconsistency and fragmentation of data significantly impedes the efficiency of tracking and analyzing human-centered records. To address this problem, we have developed a data repository and management system named TraM (http://tram.uchicago.edu), based on a domain ontology integrated entity relationship model. The TraM system has the flexibility to recruit dynamically evolving domain concepts and the ability to support data integration for a broad range of translational research. The web-based application interfaces of TraM allow curators to improve data quality and provide robust and user-friendly cross-domain query functions. In its current stage, TraM relies on a semi-automated mechanism to standardize and restructure source data for data integration and thus does not support real-time data application.\",\n \"Title: Research on Simulation of Temperature Control System for Gyro Based on Single Neuron PID\\nYear: 2010\\n\\nAbstract: In the inertial navigation system, the performance of temperature control system for gyro directly impacts on the precision and property of the inertial navigation system. The traditional control algorithm is simple, but it takes a longer time to settle the system, and the effect is not ideal. This paper presents an algorithm based on single neuron adaptive PID control, which takes advantage of self-learning, self-adaptation ability of a single neuron, can adjust the corresponding proportion, integral, differential coefficient, and achieve the rapid real-time on-line control to the temperature control system. The simulation results show that the method is efficient, because of a short period of time and small overshoot.\",\n \"Title: Spreading speeds and travelling waves for non-monotone time-delayed 2D lattice systems.\\nYear: 2013\\n\\nAbstract: In this paper, a non-monotone time delayed 2D lattice system with global interaction is studied. The important feature of the model is the reflection of the joint effect of the diffusion dynamics, the nonlocal delayed effect and the direction of propagation. The existence of travelling waves for the wave speed c≥c∗(θ) is established by Schauder’s fixed point theorem and a limiting argument, where θ is any fixed direction of propagation. The spreading speed is investigated by comparison arguments and a fluctuation method. It is also shown that the spreading speed coincides with the minimal wave speed along every direction. Particularly, letting the direction of propagation θ=0 or π2, the wave profile equation of the 2D lattice system can reduce to the wave profile equation of 1D lattice system and therefore, our results can cover the previous works.\",\n \"Title: Facilitating pharmacogenetic studies using electronic health records and natural-language processing: a case study of warfarin.\\nYear: 2011\\n\\nAbstract: Objective DNA biobanks linked to comprehensive electronic health records systems are potentially powerful resources for pharmacogenetic studies. This study sought to develop natural-language-processing algorithms to extract drug-dose information from clinical text, and to assess the capabilities of such tools to automate the data-extraction process for pharmacogenetic studies. Materials and methods A manually validated warfarin pharmacogenetic study identified a cohort of 1125 patients with a stable warfarin dose, in which 776 patients were managed by Coumadin Clinic physicians, and the remaining 349 patients were managed by their providers. The authors developed two algorithms to extract weekly warfarin doses from both data sets: a regular expression-based program for semistructured Coumadin Clinic notes; and an advanced weekly dose calculator based on an existing medication information extraction system (Med Ex) for narrative providers' notes. The authors then conducted an association analysis between an automatically extracted stable weekly dose of warfarin and four genetic variants of VKORC1 and CYP2C9 genes. The performance of the weekly dose-extraction program was evaluated by comparing it with a gold standard containing manually curated weekly doses. Precision, recall, F-measure, and overall accuracy were reported. Associations between known variants in VKORC1 and CYP2C9 and warfarin stable weekly dose were performed with linear regression adjusted for age, gender, and body mass index. Results The authors' evaluation showed that the Med Ex-based system could determine patients' warfarin weekly doses with 99.7% recall, 90.8% precision, and 93.8% accuracy. Using the automatically extracted weekly doses of warfarin, the authors successfully replicated the previous known associations between warfarin stable dose and genetic variants in VKORC1 and CYP2C9.\",\n \"Title: Finite Element Approximations for Stokes-Darcy Flow with Beavers-Joseph Interface Conditions\\nYear: 2010\\n\\nAbstract: Numerical solutions using finite element methods are considered for transient flow in a porous medium coupled to free flow in embedded conduits. Such situations arise, for example, for groundwater flows in karst aquifers. The coupled flow is modeled by the Darcy equation in a porous medium and the Stokes equations in the conduit domain. On the interface between the matrix and conduit, Beavers-Joseph interface conditions, instead of the simplified Beavers-Joseph-Saffman conditions, are imposed. Convergence and error estimates for finite element approximations are obtained. Numerical experiments illustrate the validity of the theoretical results.\",\n \"Title: IRLbot: scaling to 6 billion pages and beyond\\nYear: 2009\\n\\nAbstract: Abstract—This paper,shares,our,experience,in designing,a web,crawler that can download,billions of pages using a single- server implementation,and,models,its performance.,We,show that with,the quadratically,increasing,complexity,of verifying URL uniqueness, BFS crawl order, and fixed per-host rate- limiting, current crawling algorithms cannot effectively cope with the sheer volume of URLs generated in large crawls, highly-branching spam, legitimate multi-million-page blog sites, and,infinite loops created,by server-side scripts. We,offer a set of techniques,for dealing,with,these issues and,test their performance,in an implementation,we call IRLbot. In our recent experiment that lasted 41 days, IRLbot running on a single server successfully crawled,6:3 billion valid HTML pages,(7:6 billion connection,requests) and,sustained,an average,download,rate of 319 mb/s (1;789 pages/s). Unlike our prior experiments,with algorithms proposed in related work, this version of IRLbot did not experience any,bottlenecks and,successfully handled,content from over 117 million hosts, parsed out 394 billion links, and discovered,a subset,of the web,graph,with 41 billion unique nodes.\",\n \"Title: Real time clustering of sensory data in wireless sensor networks\\nYear: 2009\\n\\nAbstract: Data mining in wireless sensor networks (WSNs) is a new emerging research area. This paper investigates the problem of real time clustering of sensory data in WSNs. The objective is to cluster the data collected by sensor nodes in real time according to data similarity in a d-dimensional sensory data space. To perform in-network data clustering efficiently, a Hilbert Curves based mapping algorithm, HilbertMap, is proposed to convert a d-dimensional sensory data space into a two-dimensional area covered by a sensor network. Based on this mapping, a distributed algorithm for clustering sensory data, H-Cluster, is proposed. It guarantees that the communications for sensory data clustering mostly occur among geographically nearby sensor nodes and sensory data clustering is accomplished in in-network manner. Extensive simulation experiments were conducted using both real-world datasets and synthetic datasets to evaluate the algorithms. H-Cluster consistently achieves the lowest data loss rate, the highest energy efficiency, and the best clustering quality.\",\n \"Title: Modeling Heterogeneous User Churn and Local Resilience of Unstructured P2P Networks\\nYear: 2006\\n\\nAbstract: We present the design of a Network Forensic Alliance (NFA), to allow multiple administrative domains (ADs) to jointly locatethe origin of epidemic spreading attacks. ADs in the NFA collaborate in a distributed protocol for post-mortem analysis ofworm-like ...\",\n \"Title: Variable selection via combined penalization for high-dimensional data analysis\\nYear: 2010\\n\\nAbstract: We propose a new penalized least squares approach to handling high-dimensional statistical analysis problems. Our proposed procedure can outperform the SCAD penalty technique (Fan and Li, 2001) when the number of predictors p is much larger than the number of observations n, and/or when the correlation among predictors is high. The proposed procedure has some of the properties of the smoothly clipped absolute deviation (SCAD) penalty method, including sparsity and continuity, and is asymptotically equivalent to an oracle estimator. We show how the approach can be used to analyze high-dimensional data, e.g., microarray data, to construct a classification rule and at the same time automatically select significant genes. A simulation study and real data examples demonstrate the practical aspects of the new method.\",\n \"Title: Understanding and modeling the internet topology: economics and evolution perspective\\nYear: 2010\\n\\nAbstract: In this paper, we seek to understand the intrinsic reasons for the well-known phenomenon of heavy-tailed degree in the Internet AS graph and argue that in contrast to traditional models based on preferential attachment and centralized optimization, the Pareto degree of the Internet can be explained by the evolution of wealth associated with each ISP. The proposed topology model utilizes a simple multiplicative stochastic process that determines each ISP's wealth at different points in time and several \\\"maintenance\\\" rules that keep the degree of each node proportional to its wealth. Actual link formation is determined in a decentralized fashion based on random walks, where each ISP individually decides when and how to increase its degree. Simulations show that the proposed model, which we call Wealth-based Internet Topology (WIT), produces scale-free random graphs with tunable exponent α and high clustering coefficients (between 0.35 and 0.5) that stay invariant as the size of the graph increases. This evolution closely mimics that of the Internet observed since 1997.\",\n \"Title: A Spatial-temporal Model for the Malware Propagation in MWSNs Based on the Reaction-Diffusion Equations.\\nYear: 2012\\n\\nAbstract: Mobile wireless sensor networks (MWSNs) have important applications in many fields. However, MWSNs are becoming attacked targets due to its large-scale applications. The focus of this work is to develop a modeling framework and mathematical model for characterizing the process of malware propagation in MWSNs from two aspects of time and space. It is important to understand malware's potential damages, and to develop counter-measures. Firstly, we develop a formal model for describing the process of malware propagation in MWSNs based on the reaction-diffusion equations. Then, we derive the threshold for predicting whether a malware propagates or not in MWSNs as time passes. Finally, we propose the spatial pattern based method to analyze and predict the spatial distribution of nodes infected by malwares as time passes. Both theoretical analysis and extensive simulation results show that the movement speed of nodes and the communication radius of nodes have a significant effect on the malware propagation in MWSNs. © 2012 Springer-Verlag.\",\n \"Title: Approximation of stationary statistical properties of dissipative dynamical systems: Time discretization\\nYear: 2010\\n\\nAbstract: We consider temporal approximation of stationary statistical properties of dissipative infinite-dimensional dynamical systems. We demonstrate that stationary statistical properties of the time discrete approximations, i.e., numerical scheme, converge to those of the underlying continuous dissipative infinite-dimensional dynamical system under three very natural assumptions as the time step approaches zero. The three conditions that are sufficient for the convergence of the stationary statistical properties are: (1) uniform dissipativity of the scheme in the sense that the union of the global attractors for the numerical approximations is pre-compact in the phase space; (2) convergence of the solutions of the numerical scheme to the solution of the continuous system on the unit time interval [0, 1] uniformly with respect to initial data from the union of the global attractors; (3) uniform continuity of the solutions to the continuous dynamical system on the unit time interval [0, 1] uniformly for initial data from the union of the global attractors. The convergence of the global attractors is established under weaker assumptions. An application to the infinite Prandtl number model for convection is discussed.\",\n \"Title: Adaptive energy and location aware routing in wireless sensor network\\nYear: 2010\\n\\nAbstract: This paper proposes a novel routing algorithm called AELAR for wireless sensor networks to meet QoS requirements: energy conservation and data delay reduction. Firstly, we propose a novel method of dividing routing request zone and construct a select equation which can enlarge the energy awareness as network time goes on. We make the routing request zone and factors in select equation changed automatically. Simulation results show that AELAR outperforms traditional algorithms in the performance of network lifetime, utilization and consumption balancing of energy and data delay.\",\n \"Title: On zone-balancing of peer-to-peer networks: analysis of random node join\\nYear: 2004\\n\\nAbstract: Balancing peer-to-peer graphs, including zone-size distributions, has recently become an important topic of peer-to-peer (P2P) research [1], [2], [6], [19], [31], [36]. To bring analytical understanding into the various peer-join mechanisms, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic results for the maximum and minimum zone sizes that hold with high probability.\",\n \"Title: Long-time behavior for the Hele-Shaw-Cahn-Hilliard system.\\nYear: 2012\\n\\nAbstract: We study the Hele-Shaw-Cahn-Hilliard system that models two phase incompressible Darcian flow in porous media with matched density but arbitrary viscosity contrast. In the 3D case, we prove eventual regularity of weak solutions, as well as existence of global classical solutions if either the Peclet number is sufficiently small or the initial datum is close to one local energy minimizer of the free energy. In both 2D and 3D, we demonstrate that the.-limit set of each trajectory consists of a single steady state. Finally, stability of local minimizers is established.\",\n \"Title: On internal cardinal direction relations\\nYear: 2005\\n\\nAbstract: Internal Cardinal Direction (ICD) relations can be considered as the refinement to the contains/within topological relation. It is widely used to describe the position of an object in a region. In this paper, three ICD models with varying degrees of details are presented – ICD-5, ICD-9 and ICD-13. In each of these, the notion of a “middle part” is defined using Minimum Bounding Rectangles (MBR). Then focusing on ICD-9, three representation methods are discussed. They are major portion, point set of intersections and proportions of intersections respectively. The ICD-9 model is validated by a cognitive experiment, which helped to determine the size of the middle part in ICD-9 and validate the MBR-based partition method. Based on a psychological theory about vague predicates, conceptual neighborhood and intersection of ICD relations are also discussed briefly.\",\n \"Title: An efficient second order in time scheme for approximating long time statistical properties of the two dimensional Navier–Stokes equations\\nYear: 2012\\n\\nAbstract: We investigate the long time behavior of the following efficient second-order in time scheme for the 2D Navier–Stokes equations in a periodic box: $$\\\\begin{array}{ll}{\\\\frac{3\\\\omega^{n+1} - 4\\\\omega^n + \\\\omega^{n-1}}{2k} + \\\\nabla^\\\\perp(2\\\\psi^n - \\\\psi^{n-1}) \\\\cdot \\\\nabla(2\\\\omega^n - \\\\omega^{n-1})- \\\\nu\\\\Delta\\\\omega^{n+1} = f^{n+1},} \\\\\\\\ {\\\\quad -{\\\\Delta} {\\\\psi}^{n} = {\\\\omega}^{n}.}\\\\end{array}$$ The scheme is a combination of a 2nd-order in time backward-differentiation and a particular explicit Adams–Bashforth treatment of the advection term. Therefore only a linear constant coefficient Poisson solver is needed at each time step. We prove uniform in time bounds on this scheme in $${{\\\\dot{L}^2,\\\\, \\\\dot{H}^1_{per}}}$$ and $${{\\\\dot{H}^2_{per}}}$$ provided that the time-step is sufficiently small. These time uniform estimates further lead to the convergence of long time statistics (stationary statistical properties) of the scheme to that of the NSE itself at vanishing time-step.\",\n \"Title: Load-balancing performance of consistent hashing: asymptotic analysis of random node join\\nYear: 2007\\n\\nAbstract: Balancing of structured peer-to-peer graphs, including their zone sizes, has recently become an important topic of distributed hash table (DHT) research. To bring analytical understanding into the various peer-join mechanisms based on consistent hashing, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic bounds for the maximum and minimum zone sizes that hold with high probability. Several of our results contradict those of prior work and shed new light on the theoretical performance limitations of consistent hashing. We use simulations to verify our models and compare the performance of the various methods using the example of recently proposed de Bruijn DHTs.\",\n \"Title: p-Percent Coverage Schedule in Wireless Sensor Networks\\nYear: 2008\\n\\nAbstract: We investigate the p-percent coverage problem in this paper and propose two algorithms to prolong network lifetime based on the fact that for some applications full coverage is not necessary and different subareas of the monitored area may have different coverage requirements. The first algorithm, CPCA, is a centralized algorithm which selects the least number of nodes to monitor p-percent of the monitored area. The second algorithm, DPCP, is a distributed algorithm which can determine a set of nodes in a distributed manner to cover p-percent of the monitored area. Both of the algorithms guarantee network connectivity. The simulation results show that our algorithms can remarkably prolong network lifetime, have less than 5% unrequired coverage for large networks and employ nodes fairly for most cases.\",\n \"Title: Modeling Residual-Geometric Flow Sampling\\nYear: 2011\\n\\nAbstract: Traffic monitoring and estimation of flow parameters in high-speed routers have recently become challenging as the Internet grew in both scale and complexity. In this paper, we focus on a family of flow-size estimation algorithms we call Residual-Geometric Sampling (RGS), which generates a random point within each flow according to a geometric random variable and records all remaining packets in a flow counter. Our analytical investigation shows that previous estimation algorithms based on this method exhibit bias in recovering flow statistics from the sampled measurements. To address this problem, we derive a novel set of unbiased estimators for RGS, validate them using real Internet traces, and show that they provide an accurate and scalable solution to Internet traffic monitoring.\",\n \"Title: An approach for selecting seed URLs of focused crawler based on user-interest ontology.\\nYear: 2014\\n\\nAbstract: Seed URLs selection for focused Web crawler intends to guide related and valuable information that meets a user's personal information requirement and provide more effective information retrieval. In this paper, we propose a seed URLs selection approach based on user-interest ontology. In order to enrich semantic query, we first intend to apply Formal Concept Analysis to construct user-interest concept lattice with user log profile. By using concept lattice merger, we construct the user-interest ontology which can describe the implicit concepts and relationships between them more appropriately for semantic representation and query match. On the other hand, we make full use of the user-interest ontology for extracting the user interest topic area and expanding user queries to receive the most related pages as seed URLs, which is an entrance of the focused crawler. In particular, we focus on how to refine the user topic area using the bipartite directed graph. The experiment proves that the user-interest ontology can be achieved effectively by merging concept lattices and that our proposed approach can select high quality seed URLs collection and improve the average precision of focused Web crawler.\",\n \"Title: An Optimal Algorithm for Minimizing Cluster Overlap of ACE\\nYear: 2008\\n\\nAbstract: In order to reduce channel contention, support scalability and prolong the lifetime of the sensor networks, sensor nodes are often grouped into clusters. Algorithm for Cluster Establishment (ACE) is a clustering algorithm for sensor networks that uses three rounds of feedback to induce the formation of a highly efficient cover of uniform clusters over the network. In this paper, we present an optimizing algorithm for minimizing the cluster overlap of ACE. Simulation shows the proposed algorithm can efficiently eliminate the redundant cluster heads and minimize the cluster overlap.\",\n \"Title: Second-order Convex Splitting Schemes for Gradient Flows with Ehrlich-Schwoebel Type Energy: Application to Thin Film Epitaxy\\nYear: 2012\\n\\nAbstract: We construct unconditionally stable, unconditionally uniquely solvable, and second-order accurate (in time) schemes for gradient flows with energy of the form $\\\\int_\\\\Omega ( F(\\\\nabla\\\\phi({\\\\bf x})) + \\\\frac{\\\\epsilon^2}{2}|\\\\Delta\\\\phi({\\\\bf x})|^2 ) d{\\\\bf x}$. The construction of the schemes involves the appropriate combination and extension of two classical ideas: (i) appropriate convex-concave decomposition of the energy functional and (ii) the secant method. As an application, we derive schemes for epitaxial growth models with slope selection ($F({\\\\bf y})= \\\\frac14(|{\\\\bf y}|^2-1)^2$) or without slope selection ($F({\\\\bf y})=-\\\\frac12\\\\ln(1+|{\\\\bf y}|^2)$). Two types of unconditionally stable uniquely solvable second-order schemes are presented. The first type inherits the variational structure of the original continuous-in-time gradient flow, while the second type does not preserve the variational structure. We present numerical simulations for the case with slope selection which verify well-known physical scaling laws for the long time coarsening process.\",\n \"Title: Fuzzy random multi-objective optimization based routing for wireless sensor networks\\nYear: 2014\\n\\nAbstract: Wireless sensor networks are deployed in complex and uncertain environments, and multiple objectives of routing algorithms are expected to be optimal. However, routing algorithms based on deterministic single objective optimization may not flexibly meet the above needs of applications. This paper adopts fuzzy random optimization and multi-objective optimization, introduces fuzzy random variables to describe both fuzziness and randomness of link delay, link reliability and nodes' residual energy, and proposes a routing model based on fuzzy random expected value and standard deviation model. A hybrid routing algorithm based on fuzzy random multi-objective optimization is designed, which embeds fuzzy random simulation into genetic algorithm with Pareto optimal solution. Simulation results show that the presented algorithm, by adjusting the parameters of fuzzy random variables for depicting both fuzziness and randomness, achieves a longer lifetime and wider performances of delay, latency jitter, reliability, communication interference, energy and balanced energy distribution. Therefore, the presented algorithm can meet different application needs of the cluster head network in the two-tiered wireless sensor networks.\",\n \"Title: A novel privacy and copyright protection enforced peer-to-peer network\\nYear: 2005\\n\\nAbstract: Peer-to-peer (P2P) networks are widely used to share copyrighted contents and software illegally around the world. Development and applications of P2P technologies have faced strong legal and legislative challenges. A P2P network has to have built-in copyright protection to enable P2P technologies to advance on its own without court's and legislature's interference. In this paper, we propose a novel and practical P2P network with a strong privacy protection and reliable tracking mechanism to track the original uploader of any material in the P2P network. When a pirated material is found, its uploader is tracked down, and can be punished by revoking the access to the network, removing his or her uploaded materials, etc. The whole protection system is completely transparent to end users. The proposed scheme would effectively deter users from uploading illegally any copyrighted materials to and dramatically reduce copyrighted materials shared through our P2P network.\",\n \"Title: Fuzzy colored time Petri net and termination analysis for fuzzy Event-Condition-Action rules\\nYear: 2013\\n\\nAbstract: Knowledge systems are characterized by being active, uncertain and adaptive in pervasive computing environments, and Fuzzy Event-Condition-Action (ECA) rules can effectively describe these features of knowledge systems. To analyze the static structure and dynamic behavior of fuzzy ECA rules, a fuzzy colored time Petri net model (FCTPN) is proposed. The FCTPN is able to model the fuzzy ECA rules with characteristics such as fuzzy composite events, fuzzy composite conditions, event consumption modes and rule coupling modes. Based on the FCTPN, termination analysis of fuzzy ECA rules is examined, and an efficient termination analysis algorithm is proposed with consideration of all the characteristics of fuzzy ECA rules. Compared with existing termination analysis algorithms of ECA rules, the proposed algorithm has higher accuracy and lower time complexity, and thus it is more suitable for pervasive computing environments.\",\n \"Title: On minimum class locality preserving variance support vector machine\\nYear: 2010\\n\\nAbstract: In this paper, a so-called minimum class locality preserving variance support machine (MCLPV_SVM) algorithm is presented by introducing the basic idea of the locality preserving projections (LPP), which can be seen as a modified class of support machine (SVM) and/or minimum class variance support machine (MCVSVM). MCLPV_SVM, in contrast to SVM and MCVSVM, takes the intrinsic manifold structure of the data space into full consideration and inherits the characteristics of SVM and MCVSVM. We discuss in the paper the linear case, the small sample size case and the nonlinear case of the MCLPV_SVM. Similar to MCVSVM, the MCLPV_SVM optimization problem in the small sample size case is solved by using dimensionality reduction through principal component analysis (PCA) and one in the nonlinear case is transformed into an equivalent linear MCLPV_SVM problem under kernel PCA (KPCA). Experimental results on real datasets indicate the effectiveness of the MCLPV_SVM by comparing it with SVM and MCVSVM.\",\n \"Title: Using virtual ATE model to migrate test programs\\nYear: 1995\\n\\nAbstract: Because of high development costs of IC (Integrated Circuit) test programs, recycling existing test programs from one kind\\n of ATE (Automatic Test Equipment) to another or generating directly from CAD simulation modules to ATE is more and more valuable.\\n In this paper, a new approach to migrating test programs is presented. A virtual ATE model based on object-oriented paradigm\\n is developed; it runs Test C++ (an intermediate test control language) programs and TeIF (Test Intermediate Format—an intermediate\\n pattern), migrates test programs among three kinds of ATE (Ando DIC8032, Schlumberger S15 and GenRad 1732) and generates test\\n patterns from two kinds of CAD (Daisy and Panda) automatically.\",\n \"Title: A level-set based variational method for design and optimization of heterogeneous objects\\nYear: 2005\\n\\nAbstract: A heterogeneous object is referred to as a solid object made of different constituent materials. The object is of a finite collection of regions of a set of prescribed material classes of continuously varying material properties. These properties have a discontinuous change across the interface of the material regions. In this paper, we propose a level-set based variational approach for the design of this class of heterogeneous objects. Central to the approach is a variational framework for a well-posed formulation of the design problem. In particular, we adapt the Mumford–Shah model which specifies that any point of the object belongs to either of two types: inside a material region of a well-defined gradient or on the boundary edges and surfaces of discontinuities. Furthermore, the set of discontinuities is represented implicitly, using a multi-phase level set model. This level-set based variational approach yields a computational system of coupled geometric evolution and diffusion partial differential equations. Promising features of the proposed method include strong regularity in the problem formulation and inherent capabilities of geometric and material modeling, yielding a common framework for optimization of the heterogeneous objects that incorporates dimension, shape, topology, and material properties. The proposed method is illustrated with several 2D examples of optimal design of multi-material structures and materials.\",\n \"Title: The Development of E-Commerce under the Influence of China Mobile Communications\\nYear: 2010\\n\\nAbstract: The development of E-Commerce under the influence of China Mobile Communications\",\n \"Title: Node isolation model and age-based neighbor selection in unstructured P2P networks\\nYear: 2009\\n\\nAbstract: Previous analytical studies of unstructured P2P resilience have assumed exponential user lifetimes and only con-sidered age-independent neighbor replacement. In this paper, we overcome these limitations by introducing a general node-isolation model for heavy-tailed user lifetimes and arbitrary neighbor-se-lection algorithms. Using this model, we analyze two age-biased neighbor-selection strategies and show that they significantly improve the residual lifetimes of chosen users, which dramatically reduces the probability of user isolation and graph partitioning compared with uniform selection of neighbors. In fact, the second strategy based on random walks on age-proportional graphs demonstrates that, for lifetimes with infinite variance, the system monotonically increases its resilience as its age and size grow. Specifically, we show that the probability of isolation converges to zero as these two metrics tend to infinity. We finish the paper with simulations in finite-size graphs that demonstrate the effect of this result in practice.\",\n \"Title: Study on Embedded System Grid\\nYear: 2005\\n\\nAbstract: The center of gravity of the computer industry is now moving from personal computing into embedded computing. At present, the key to realize intellectual control and network control of manufacturing equipments is to embed the embedded system into manufacturing equipment and extend the control method of manufacturing equipments to the remote network through the network function of the embedded system. In this paper, the characteristic of embedded system and the architecture of embedded system grid are introduced firsty. Then, the interface method between embedded system and grid are discussed. The control model of embedded system resources under the grid environment, the method of overall sharing embedded system and its equipment are also describled. After that, the embedded system grid technology of sharing and controlling embedded resources are presented.\",\n \"Title: An Adaptive State Detection Service for Manufacturing Grid.\\nYear: 2007\\n\\nAbstract: Manufacturing grid serves as a distributed platform for integrating manufacturing resources and offering shared service. The state knowledge of the manufacturing resources is recorded efficiently. Thus resource exceptions can be timely noticed and removed to ensure reliable service. Given the features of manufacturing grid and the strategy of failure detector in the mode of PULL, this paper proposes a new mode of state detection algorithm for manufacturing grid. This algorithm is capable of meeting various demands of all kinds of manufacturing resources, and supporting the strategy of scheduling priority of local resources demanding no clock synchronization. Data from a manufacturing grid test bed shows that the algorithm can accurately and dynamically record the resource state, and it can meet the demands of resource detection in the manufacturing grid.\",\n \"Title: Robust lifetime measurement in large-scale P2P systems with non-stationary arrivals\\nYear: 2009\\n\\nAbstract: Characterizing user churn has become an important topic in studying P2P networks, both in theoretical analysis and system design. Recent work has shown that direct sampling of user lifetimes may lead to certain bias (arising from missed peers and round-off inconsistencies) and proposed a technique that estimates lifetimes based on sampled residuals. In this paper, however, we show that under non-stationary arrivals, which are often present in real systems, residual-based sampling does not correctly reconstruct user lifetimes and suffers a varying degree of bias, which in some cases makes estimation completely impossible. We overcome this problem using two contributions: a novel non-stationary ON/OFF churn model and an unbiased randomized residual sampling technique for measuring user lifetimes. The former allows correlation between ON/OFF periods of the same user and exhibits different join rates during the day. The latter spreads sampling points uniformly during the day and uses a novel estimator to reconstruct the underlying lifetime distribution. We finish the paper with experimental measurements of Gnutella and discussing reduction in overhead compared to direct sampling methods.\",\n \"Title: Analysis of Nonlinear Spectral Eddy-Viscosity Models of Turbulence\\nYear: 2010\\n\\nAbstract: Fluid turbulence is commonly modeled by the Navier-Stokes equations with a large Reynolds number. However, direct numerical simulations are not possible in practice, so that turbulence modeling is introduced. We study artificial spectral viscosity models that render the simulation of turbulence tractable. We show that the models are well posed and have solutions that converge, in certain parameter limits, to solutions of the Navier-Stokes equations. We also show, using the mathematical analyses, how effective choices for the parameters appearing in the models can be made. Finally, we consider temporal discretizations of the models and investigate their stability.\",\n \"Title: A Linear Iteration Algorithm for a Second-Order Energy Stable Scheme for a Thin Film Model Without Slope Selection\\nYear: 2014\\n\\nAbstract: We present a linear iteration algorithm to implement a second-order energy stable numerical scheme for a model of epitaxial thin film growth without slope selection. The PDE, which is a nonlinear, fourth-order parabolic equation, is the $$L^2$$ L 2 gradient flow of the energy $$ \\\\int _\\\\Omega \\\\left( - \\\\frac{1}{2} \\\\ln \\\\left( 1 + | \\\\nabla \\\\phi |^2 \\\\right) + \\\\frac{\\\\epsilon ^2}{2}|\\\\Delta \\\\phi (\\\\mathbf{x})|^2 \\\\right) \\\\mathrm{d}\\\\mathbf{x}$$ 驴 Ω - 1 2 ln 1 + | 驴 驴 | 2 + ∈ 2 2 | Δ 驴 ( x ) | 2 d x . The energy stability is preserved by a careful choice of the second-order temporal approximation for the nonlinear term, as reported in recent work (Shen et al. in SIAM J Numer Anal 50:105---125, 2012). The resulting scheme is highly nonlinear, and its implementation is non-trivial. In this paper, we propose a linear iteration algorithm to solve the resulting nonlinear system. To accomplish this we introduce an $$O(s^2)$$ O ( s 2 ) (with $$s$$ s the time step size) artificial diffusion term, a Douglas-Dupont-type regularization, that leads to a contraction mapping property. As a result, the highly nonlinear system can be decomposed as an iteration of purely linear solvers, which can be very efficiently implemented with the help of FFT in a collocation Fourier spectral setting. We present a careful analysis showing convergence for the numerical scheme in a discrete $$L^\\\\infty (0, T; H^1) \\\\cap L^2 (0,T; H^3)$$ L 驴 ( 0 , T ; H 1 ) 驴 L 2 ( 0 , T ; H 3 ) norm. Some numerical simulation results are presented to demonstrate the efficiency of the linear iteration solver and the convergence of the scheme as a whole.\",\n \"Title: Modeling the Evolution of Degree Correlation in Scale-Free Topology Generators\\nYear: 2008\\n\\nAbstract: In this paper, we examine the asymptotic behavior of degree correlation (i.e., the joint degree distribution of adjacent nodes) in several scale-free topology generators GED [13], PLRG [1], GLP [10], BA [3], AB [2]. We present a unifying analytical framework that allows tractable analysis of degree correlation in all studied models and derive asymptotic formulas of two degree correlation metrics - assortativity and clustering. Our results indicate that all studied generators become uncorrelated as graph size increases, which is inconsistent with time-invariance of these metrics in real networks such as the Internet [36], [48], [50]. Since the class of degree-based generators is incapable of reproducing evolving characteristics of the Internet, we study three other models that evolve graphs using different rules than preference of degree (e.g., based on random walks [50], optimization [17], and geometry [23]) and show using simulations that these models are much more viable alternatives for replicating the complex structure of Internet-like graphs.\",\n \"Title: A Parallel Robin-Robin Domain Decomposition Method for the Stokes-Darcy System\\nYear: 2011\\n\\nAbstract: We propose a new parallel Robin-Robin domain decomposition method for the coupled Stokes-Darcy system with Beavers-Joseph-Saffman-Jones interface boundary condition. In particular, we prove that, with an appropriate choice of parameters, the scheme converges geometrically independent of the mesh size.\",\n \"Title: Residual-Based Measurement of Peer and Link Lifetimes in Gnutella Networks\\nYear: 2007\\n\\nAbstract: Existing methods of measuring lifetimes in P2P systems usually rely on the so-called create-based method (CBM), which divides a given observation window into two halves and samples users \\\"created\\\" in the first half every Delta time units until they die or the observation period ends. Despite its frequent use, this approach has no rigorous accuracy or overhead analysis in the literature. To shed more light on its performance, we flrst derive a model for CBM and show that small window size or large Delta may lead to highly inaccurate lifetime distributions. We then show that create-based sampling exhibits an inherent tradeoff between overhead and accuracy, which does not allow any fundamental improvement to the method. Instead, we propose a completely different approach for sampling user dynamics that keeps track of only residual lifetimes of peers and uses a simple renewal-process model to recover the actual lifetimes from the observed residuals. Our analysis indicates that for reasonably large systems, the proposed method can reduce bandwidth consumption by several orders of magnitude compared to prior approaches while simultaneously achieving higher accuracy. We finish the paper by implementing a two-tier Gnutella network crawler equipped with the proposed sampling method and obtain the distribution of ultrapeer lifetimes in a network of 6.4 million users and 60 million links. Our experimental results show that ultrapeer lifetimes are Pareto with shape a alpha ap 1.1; however, link lifetimes exhibit much lighter tails with alpha ap 1.9.\",\n \"Title: Research on a Super-Sparse Data Generation Model for Temperature Data Map.\\nYear: 2013\\n\\nAbstract: Data visualization is an important method in data mining, and temperature data map is one of the methods of data visualization. When sample temperature points are limited, it brings the main content of the research on how to build a temperature data map, namely how to use super-sparse date to generate a data map. Based on the fact that temperature energy keeps constant, this paper proposes a diffusion model which uses the known temperature data to predict the unknown values. Furthermore, this paper improves the model by adding the influence of wind to make a better temperature data map. Taking the area of Shandong Province as an example, we can only get 17 cities' annual average temperature, then how to make a whole map of Shandong area confronts us. Experimental results verified that the proposed diffusion models turn out to be feasible. © 2013 Springer-Verlag Berlin Heidelberg.\",\n \"Title: Energy-efficient downlink transmission in multi-cell coordinated beamforming systems\\nYear: 2013\\n\\nAbstract: Coordinated multipoint has been widely introduced to enhance the capacity, especially that of users at cell edge. Recently energy efficient transmission techniques are increasingly important due to the increase of energy consumption in wireless communication systems. In this paper, an energy efficient cooperative transmission algorithm using coordinated beamforming is proposed for multi-cell MIMO networks. We formulate the problem as a non-convex optimization problem in a fractional form. Then we transform the problem into an equivalent form and propose an iterative algorithm to solve it. In each iteration, a simplified zero-forcing coordinated beamforming using beam tracing and an optimal power allocation algorithm for maximizing energy efficiency are derived. Simulation results demonstrate that the proposed algorithm has a better energy efficiency performance than the traditional capacity maximizing method. With the lower complexity, the proposed method using beam tracing approaches the energy efficiency performance of the subspace decomposition method in slowly varying channels.\",\n \"Title: A Semi-Implicit Scheme for Stationary Statistical Properties of the Infinite Prandtl Number Model\\nYear: 2008\\n\\nAbstract: We propose a semidiscrete in time semi-implicit numerical scheme for the infinite Prandtl model for convection. Besides the usual finite time convergence, this scheme enjoys the additional highly desirable feature that the stationary statistical properties of the scheme converge to those of the infinite Prandtl number model at vanishing time step. One of the key characteristics of the scheme is that it preserves the dissipativity of the infinite Prandtl number model uniformly in terms of the time step. So far as we know, this is the first rigorous result on convergence of stationary statistical properties of numerical schemes for infinite dimensional dissipative complex systems.\",\n \"Title: Damping Characteristic of Composite Material with Periodic Micro-Tetrahedron Structures\\nYear: 2011\\n\\nAbstract: Research on damping characteristic of structures and materials is always one of the studies of international grand issue. Here, we addressed the damping characteristic of composite material with periodic micro-tetrahedron structures. We estabLished two computational models: one is a composite material model with periodic micro-tetrahedron structure, and another is the mass point model with periodic micro-tetrahedron structures. The unit cell of the first model is the micro-tetrahedron structure, in which the six edges are made of steel, and all the other areas are filled with a kind of high damping material such as rubber. In order to improve the damping characteristic of the first model, we transform the first model into the second model by applying a centraLized mass to the center of every parallelepiped, which consist of six micro-tetrahedron structures. By analyzing and comparing the damping characteristic of the two models, it can be concluded that the damping characteristic of the mass point model is better, and properly choosing the weight of the centraLized mass can improve the damping characteristic of the structure.\",\n \"Title: A uniformly dissipative scheme for stationary statistical properties of the infinite Prandtl number model\\nYear: 2008\\n\\nAbstract: The purpose of this short communication is to announce that a class of numerical schemes, uniformly dissipative approximations, which uniformly preserve the dissipativity of the continuous infinite dimensional dissipative complex (chaotic) systems possess desirable properties in terms of approximating stationary statistics properties. In particular, the stationary statistical properties of these uniformly dissipative schemes converge to those of the continuous system at vanishing mesh size. The idea is illustrated on the infinite Prandtl number model for convection and semi-discretization in time, although the general strategy works for a broad class of dissipative complex systems and fully discretized approximations. As far as we know, this is the first result on rigorous validation of numerical schemes for approximating stationary statistical properties of general infinite dimensional dissipative complex systems.\",\n \"Title: Theoretical analysis for solution of support vector data description.\\nYear: 2011\\n\\nAbstract: As we may know well, uniqueness of the Support Vector Machines (SVM) solution has been solved. However, whether Support Vector Data Description (SVDD), another best-known machine learning method, has a unique solution or not still remains unsolved. Due to the fact that the primal optimization of SVDD is not a convex programming problem, it is difficult for us to theoretically analyze the SVDD solution in an analogous way to SVM. In this paper, we concentrate on the theoretical analysis for the solution to the primal optimization problem of SVDD. We first reformulate equivalently the primal optimization problem of SVDD into a convex programming problem, and then prove that the optimal solution with respect to the sphere center is unique, derive the necessary and sufficient conditions of non-uniqueness of the optimal solution with respect to the sphere radius in the primal optimization problem of SVDD. Moreover, we also explore the property of the SVDD solution from the perspective of the SVDD dual form. Furthermore, according to the geometric interpretation of SVDD, a method of computing the sphere radius is proposed when the optimal solution with respect to the sphere radius in the primal optimization problem is non-unique. Finally, we have several examples to illustrate these findings.\",\n \"Title: ICTSSE: An object-oriented IC test software supporting environment\\nYear: 1995\\n\\nAbstract: An IC test software supporting environment—ICTSSE, which supports the migration and simulation of test pattern programs on\\n heterogeneous ATEs, is presented. ICTSSE is a subsystem of Test Development System (TeDS). It has the capabilities of verifying\\n the IC’s stimulus/response vectors and associated timing resources against the target ATE. The general data interchange format,\\n which is the center of the TEDS, is built for test pattern migration.\",\n \"Title: An efficient and scalable pairwise key pre-distribution scheme for sensor networks using deployment knowledge\\nYear: 2009\\n\\nAbstract: Pairwise key establishment is a fundamental security service for sensor networks. However, establishing pairwise key in sensor networks is a challenging problem, particularly due to the resource constraints on sensor nodes and the threat of node compromises. On the other hand, adding new nodes to a sensor network is a fundamental requirement for their continuous operation over time, too. We analyze the weaknesses of security due to node capture when adding sensor nodes using key pre-distribution schemes with ''fixed'' key pools. In this paper, we propose a new approach, which separates the nodes into groups, the nodes in a group communicate with each other using pairwise keys pre-distributed, the communications between any two neighbor groups are accomplished also through pairwise keys, which is computed based on the pre-distributed Hash chain. We show that the performance (e.g. continuous connectivity, continuous network resilience against node capture and memory usage) of sensor networks can be substantially improved by using our scheme. The scheme and its detailed performance evaluation are presented.\",\n \"Title: Dem-Based Study Of Habitat Characteristics Of Torreya Fengqiao In Kuaiji Mountain, China\\nYear: 2008\\n\\nAbstract: The habitat characteristics of Torreya were investigated based oil high resolution DEM and remote sensing image. The distribution of Torreya was mapped by visual interpretation of IKONOS image. The landform and PCA analysis results showed that Curvature, attitude, aspect and slope were found to be the dominant features controlling spatial distribution pattern of Torreya. A certain degree Moisture related variables were proved to be the most important parameters to explain Torreya habitats preferences. The preferable habitat requirement for Torreya focused oil those concave and southwest hillsides with elevation between 400 and 600 in and slope less than 30 degrees.\",\n \"Title: An Encryption Scheme with Hidden Keyword Search for Outsourced Database.\\nYear: 2011\\n\\nAbstract: An encryption scheme with hidden keyword search is proposed for Outsourced Database. In the proposed scheme, both pseudorandom function and polynomial function are employed in order to reduce computation and shortage overhead. The proposed scheme can not only provide controlled searching, and hidden searching as well as the provable secrecy for encryption, but also support the dynamic change of the permitted group users and be transparent to user when the users are added and removed since they are not involved in the process. Moreover, there is no interaction between database owner and server, server and user or database owner and user when the decrypted key is set up. Each user is only required to receive messages to setup their decrypted key and hence can query over encrypted data and decrypt the encrypted data. Therefore, the proposed scheme is more efficient and more practical for outsourced database. © 2011 ACADEMY PUBLISHER.\",\n \"Title: Numerical Simulation and Forecasting of Water Level for Qinghai Lake Using Multi-Altimeter Data Between 2002 and 2012\\nYear: 2014\\n\\nAbstract: Satellite radar altimetry has effectively been used for monitoring the water level change in recent years. In this study, Qinghai Lake was taken as an example to simulate and forecast water level using the multi-altimeter data from Envisat/RA-2, Cryosat-2/Siral, and Jason-1/Poseidon-2. First, using the robust least square method and system bias correction algorithms, abnormal water levels and the system bias were eliminated, and an accurate lake-level time series was obtained. Then, singular spectrum analysis (SSA) algorithms were used to extract the effective fluctuation signal from the accurate lake-level time series, and the accuracy of the altimetry data was improved. Based on an analysis of SSA algorithms' characteristics, comparison of the SSA-extracted fluctuation signal, and in-situ gauge measurements of Qinghai Lake, the accurate lake-level time series was affected by white noise of zero-mean and 0.5-m variance and colored noise of 0.2202-0.2473-m mean and 0.252-0.2800-m root-mean-square difference. After eliminating the white noise, the accuracy of the altimeter data reached the decimeter level in inland lake monitoring. Next, the SSA-extracted fluctuation signal was decomposed into linear composition, periodic components, and a residual component, and a combined linear-periodic-residual model was established using simple regression, a trigonometric function, and autoregressive-moving-average models. Using the model, the water level change of Qinghai Lake was simulated and forecasted to 2 years, with its accuracy reaching the decimeter level. The experiences of this study can provide an effective reference for the other lakes.\",\n \"Title: A Low-Complexity Energy-Efficient Power Allocation and Rate Adaptation Scheme for Relay-Assisted Systems\\nYear: 2015\\n\\nAbstract: In this letter, an energy-efficient power and rate adaptation algorithm for amplify-and-forward (AF) relay systems is studied with imperfect channel statement information (CSI) at transmitters. In the proposed scheme, energy efficiency (EE) is maximized under the maximum transmit power constraint, the minimum system data-rate constraint and the target packet outage probability constraint. In addition, to solve the EE maximization problem, we propose a low-complexity iterative algorithm. Numerical results illustrate the effectiveness of the proposed algorithm.\",\n \"Title: Energy-Efficient Resource Allocation in Coordinated Downlink Multi-cell OFDMA Systems\\nYear: 2016\\n\\nAbstract: In this paper, a resource allocation algorithm for maximizing the energy efficiency (EE) is studied in multi-cell orthogonal frequency division multiple access (OFDMA) wireless networks. The resource allocation is designed based on imperfect channel state information (CSI). Universal frequency reuse is considered and co-channel interference is dealt with via the cooperation of multiple base stations (BSs) sharing CSI but not user data. We formulate the energy-efficient resource allocation problem as a probabilistic mixed non-convex optimization problem. The user scheduling, data rate adaptation and power allocation are jointly designed to maximize the system EE, under the maximum transmitted power constraint and the outage probability constraint. An iterative algorithm is proposed in which the EE keeps improving until algorithm convergence. In each iteration, the energy-efficient power allocation optimization problem is solved by a lower bound problem and a parameterized transformation. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm. In a multi-cell environment with co-channel interference, the proposed algorithm has large EE gains relative to the spectral efficiency (SE) loss. Compared with non-coordinated methods, the proposed method can achieve higher EE when backhaul power consumption is low.\",\n \"Title: Secondary use of clinical data: The Vanderbilt approach.\\nYear: 2014\\n\\nAbstract: The last decade has seen an exponential growth in the quantity of clinical data collected nationwide, triggering an increase in opportunities to reuse the data for biomedical research. The Vanderbilt research data warehouse framework consists of identified and de-identified clinical data repositories, fee-for-service custom services, and tools built atop the data layer to assist researchers across the enterprise. Providing resources dedicated to research initiatives benefits not only the research community, but also clinicians, patients and institutional leadership. This work provides a summary of our approach in the secondary use of clinical data for research domain, including a description of key components and a list of lessons learned, designed to assist others assembling similar services and infrastructure.\",\n \"Title: Stability and bifurcation analysis in a delayed reaction-diffusion malware propagation model\\nYear: 2015\\n\\nAbstract: Mobile wireless sensor networks (MWSNs) have become an area of intense research activity due to technical advances in sensors, wireless communications and networking, and signal processing. Many applications, including environment monitoring, battlefield surveillance, and urban search and rescue especially in hazardous situations, are envisaged. However, MWSNs may be vulnerable to malicious interference because of the large-scale characteristics. When a contaminated node communications with its neighbors, multiple copies of the malware are transmitted to its neighbors, which may destroy, block regular communications, or even damage the integrity of regular data packets. Modeling spatial distribution of malware propagation over time is the first step to predict the trend of malware propagation in MWSNs. We propose a novel wireless malware propagation model with the discrete time delay based on reaction-diffusion equations in mobile wireless sensor networks, and study its dynamic behaviors. By analyzing the stability and Hopf bifurcation of the equilibrium of our model, we search for the sufficient conditions, which leads to the malware propagation disappears or continues. Furthermore, we demonstrate that oscillations in this model occur through the destabilization of the stationary solution at a Hopf bifurcation point. And formulas for determining the stability of the bifurcating periodic oscillations are derived by applying the normal form method and center manifold theorem. Finally, we conduct extensive simulations on large-scale MWSNs to evaluate the proposed model. Numerical evidence shows that the spatial-temporal dynamic characteristics of malware propagation in MWSNs are closely related to the packet transmission rate, the communication rang and the mobile behavior of nodes.\",\n \"Title: Data integrity verification scheme with designated verifiers for dynamic outsourced databases.\\nYear: 2014\\n\\nAbstract: In order to verify the integrity of the query results in outsourced database model, we first present a new authenticated data structure by combining skip lists with polynomial functions and accumulators and then construct a data integrity verification scheme for range query. Our scheme can verify the integrity of the query results with constant time verification and constant size proof and support dynamic maintenance with constant computational cost. Compared with that of previous schemes, the communication cost in our scheme is independent of the size of the authenticated dataset and is lower. When dataset size gets larger enough, our scheme outperforms previous schemes in terms of the computational cost and verification cost. In addition, we introduce the designated verifier idea into our scheme, so our scheme achieves the result that none but subscribers can verify the integrity of the query results and then meets the practical demands such as the payment service. The proof of security and analysis of experiment performance show that our scheme is secure and efficient for larger outsourced databases. Copyright (c) 2013 John Wiley & Sons, Ltd.\",\n \"Title: Gene set enrichment analysis for multiple continuous phenotypes.\\nYear: 2014\\n\\nAbstract: Gene set analysis (GSA) methods test the association of sets of genes with phenotypes in gene expression microarray studies. While GSA methods on a single binary or categorical phenotype abounds, little attention has been paid to the case of a continuous phenotype, and there is no method to accommodate correlated multiple continuous phenotypes.We propose here an extension of the linear combination test (LCT) to its new version for multiple continuous phenotypes, incorporating correlations among gene expressions of functionally related gene sets, as well as correlations among multiple phenotypes. Further, we extend our new method to its nonlinear version, referred as nonlinear combination test (NLCT), to test potential nonlinear association of gene sets with multiple phenotypes. Simulation study and a real microarray example demonstrate the practical aspects of the proposed methods.The proposed approaches are effective in controlling type I errors and powerful in testing associations between gene-sets and multiple continuous phenotypes. They are both computationally effective. Naively (univariately) analyzing a group of multiple correlated phenotypes could be dangerous. R-codes to perform LCT and NLCT for multiple continuous phenotypes are available at http://www.ualberta.ca/~yyasui/homepage.html.\",\n \"Title: Improved pseudo nearest neighbor classification.\\nYear: 2014\\n\\nAbstract: k-Nearest neighbor (KNN) rule is a very simple and powerful classification algorithm. In this article, we propose a new KNN-based classifier, called the local mean-based pseudo nearest neighbor (LMPNN) rule. It is motivated by the local mean-based k-nearest neighbor (LMKNN) rule and the pseudo nearest neighbor (PNN) rule, with the aim of improving the classification performance. In the proposed LMPNN, the k nearest neighbors from each class are searched as the class prototypes, and then the local mean vectors of the neighbors are yielded. Subsequently, we attempt to find the local mean-based pseudo nearest neighbor per class by employing the categorical k local mean vectors, and classify the unknown query patten according to the distances between the query and the pseudo nearest neighbors. To assess the classification performance of the proposed LMPNN, it is compared with the competing classifiers, such as LMKNN and PNN, in terms of the classification error on thirty-two real UCI data sets, four artificial data sets and three image data sets. The comprehensively experimental results suggest that the proposed LMPNN classifier is a promising algorithm in pattern recognition.\",\n \"Title: Signal power random fading based interference-aware routing for wireless sensor networks\\nYear: 2014\\n\\nAbstract: Power loss and interference coexist in wireless transmissions where random uncertainty is aggravated due to the mobility of sensor nodes. A probability interference model was proposed, based on the physical model and random fading of the received signal power, to depict the uncertainty of wireless interference. In addition, an interference-aware routing metric was designed, in which interference, routing convergence and residual energies of nodes were integrated. Furthermore, an interference-aware probabilistic routing algorithm was proposed for mobile wireless sensor networks, and its correctness and time and space complexities were proved. The NS-2 simulation experiments showed that the proposed algorithm can achieve higher packet delivery ratio than Greedy Perimeter Stateless Routing in various cases like the pause time and maximum moving speed. Simultaneously, the energy consumption of a packet and average delay were taken into consideration to better meet the needs of mobile scenarios with higher reliability.\",\n \"Title: Study on Sparse Representation based Classification for Biometric Verification.\\nYear: 2015\\n\\nAbstract: In this paper, we propose a multimodal verification system integrating face and ear based on sparse representation based classification (SRC). The face and ear query samples are first encoded separately to derive sparsity-based match scores, and which are then combined with sum-rule fusion for verification. Apart from validating the encouraging performance of SRC-based multimodal verification, this paper also dedicates to provide a clear understanding about the characteristics of SRC-based biometric verification. To this end, two sparsity-based metrics, i.e. spare coding error (SCE) and sparse contribution rate (SCR), are involved, together with face and ear unimodal SRC-based verification. As for the issue that SRC-based biometric verification may suffer from heavy computational burden and verification accuracy degradation with increase of enrolled subjects, we argue that it could be properly resolved by exploiting small random dictionary for sparsity-based score computation, which consists of training samples from a limited number of randomly selected subjects. Experimental results demonstrate the superiority of SRC-based multimodal verification compared to the state-of-the-art multimodal methods like likelihood ratio (LLR), support vector machine (SVM), and the sum-rule fusion methods using cosine similarity, meanwhile the idea of using small random dictionary is feasible in both effectiveness and efficiency.\",\n \"Title: Energy Efficiency of Cross-Tier Base Station Cooperation in Heterogeneous Cellular Networks.\\nYear: 2014\\n\\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about energy efficiency. Base station (BS) cooperation is set to play a key role in managing interference in the HetNets. In this paper, we consider BS cooperation in the downlink HetNets where BSs from different tiers within the respective cooperative clusters jointly transmit the same data to a typical user, and further optimize the energy efficiency performance. First, based on the proposed clustering model, we derive the spatial average rate using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with a minimum spatial average rate constraint and derive an approximate result of the optimal received signal strength (RSS) thresholds. Building upon these results, we effectively address the problem of how to design appropriate RSS thresholds, taking into account the trade-off between spatial average rate and energy efficiency. Simulations show that our proposed clustering model is more energy-saving than the geometric clustering model, and under our proposed clustering model, deploying a two-tier HetNet is significantly more energy-saving compared to a macro-only network.\",\n \"Title: Parallel, non-iterative, multi-physics domain decomposition methods for time-dependent Stokes-Darcy systems.\\nYear: 2014\\n\\nAbstract: Two parallel, non-iterative, multi-physics, domain decomposition methods are proposed to solve a coupled time-dependent Stokes-Darcy system with the Beavers-Joseph-Saffman-Jones interface condition. For both methods, spatial discretization is effected using finite element methods. The backward Euler method and a three-step backward differentiation method are used for the temporal discretization. Results obtained at previous time steps are used to approximate the coupling information on the interface between the Darcy and Stokes subdomains at the current time step. Hence, at each time step, only a single Stokes and a single Darcy problem need be solved; as these are uncoupled, they can be solved in parallel. The unconditional stability and convergence of the first method is proved and also illustrated through numerical experiments. The improved temporal convergence and unconditional stability of the second method is also illustrated through numerical experiments.\",\n \"Title: A second order in time, uniquely solvable, unconditionally stable numerical scheme for Cahn-Hilliard-Navier-Stokes equation\\nYear: 2015\\n\\nAbstract: We propose a novel second order in time numerical scheme for Cahn-Hilliard-Navier-Stokes phase field model with matched density. The scheme is based on second order convex-splitting for the Cahn-Hilliard equation and pressure-projection for the Navier-Stokes equation. We show that the scheme is mass-conservative, satisfies a modified energy law and is therefore unconditionally stable. Moreover, we prove that the scheme is unconditionally uniquely solvable at each time step by exploring the monotonicity associated with the scheme. Thanks to the simple coupling of the scheme, we design an efficient Picard iteration procedure to further decouple the computation of Cahn-Hilliard equation and Navier-Stokes equation. We implement the scheme by the mixed finite element method. Ample numerical experiments are performed to validate the accuracy and efficiency of the numerical scheme.\",\n \"Title: Unifying Models of Churn and Resilience for Unstructured P2P Graphs\\nYear: 2014\\n\\nAbstract: Previous analytical results on the resilience of unstructured P2P systems have not explicitly modeled heterogeneity of user churn (i.e, difference in online behavior) or the impact of in-degree on system resilience. To overcome these limitations, we introduce a unifying model of heterogeneous user churn and derive the distribution of the various metrics observed in prior experimental studies. We also show that the arrival process of in-edges to each user converges to Poisson when system size tends to infinity, model transient behavior of in-degree, and apply these results to obtain the joint in/out-degree isolation probability.\",\n \"Title: Approximation algorithms for the three-stage flexible flow shop problem with mid group constraint.\\nYear: 2015\\n\\nAbstract: •We propose ten heuristics for that problem and give their time complexities.•We give 4 lower bounds for that problem and worst case rates of nine heuristics.•We design a computational experiment to test the performance of ten heuristics.•SP.JH-MJ is best and TSM is the worst among the ten heuristics by the experiment.\",\n \"Title: Energy-efficient base station cooperation in downlink heterogeneous cellular networks\\nYear: 2014\\n\\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about energy efficiency. In this paper, we consider the base station (BS) cooperation solution for improving energy efficiency of the HetNets where BSs from each tier within the cooperative cluster jointly transmit the same data to a typical user. Firstly, based on the proposed clustering model, we precisely derive the ergodic rate expression using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with minimum ergodic rate constraint and derive a closed-form approximated result of the optimal cooperative radii. Building upon these results, we could effectively address the problem how to design appropriate cooperative radii, taking into account the trade-off of ergodic rate and energy efficiency. Simulation results also indicate that under the proposed clustering model, deploying a two-tier HetNet is more energy-saving compared to a macro-only network.\",\n \"Title: One Kind of Cross-Domain DAA Scheme from Bilinear Mapping\\nYear: 2014\\n\\nAbstract: Direct anonymous attestation was adopted by TCG organization for authenticating remote trusted computing platform. Its advantage is that we can protect the privacy of the platform. Since DAA is a unidirectional authentication, it can't resist the platform masquerading attacks. Because DAA scheme has unidirectional authentication security flaws, the proposed method key negotiation, successfully repairs the defects. In practical applications, there may be a case of multiple trust domains, but most of the existing DAA programs don't support across trust domains. For this limitation, by introducing cross domain certificate issuer, using CL-LRSW signature successfully solve the problem of cross trust domains. After analysis, the scheme satisfies anonymity, enforceability, unlinkability, and can effectively resist platform masquerading attacks.\",\n \"Title: Graph-theoretic analysis of structured peer-to-peer systems: routing distances and fault resilience\\nYear: 2005\\n\\nAbstract: This paper examines graph-theoretic properties of existing peer-to-peer networks and proposes a new infrastructure based on optimal-diameter de Bruijn graphs. Since generalized de Bruijn graphs exhibit very short average distances and high resilience to node failure, they are well suited for distributed hash tables (DHTs). Using the example of Chord, CAN, and de Bruijn, we study the routing performance, graph expansion, clustering properties, and bisection width of each graph. Having confirmed that de Bruijn graphs offer the best diameter and highest connectivity among the existing peer-to-peer structures, we offer a very simple incremental building process that preserves optimal properties of de Bruijn graphs under uniform user joins/departures. We call the combined peer-to-peer architecture optimal diameter routing infrastructure.\",\n \"Title: On Static and Dynamic Partitioning Behavior of Large-Scale P2P Networks\\nYear: 2008\\n\\nAbstract: In this paper, we analyze the problem of network disconnection in the context of large-scale P2P networks and understand how both static and dynamic patterns of node failure affect the resilience of such graphs. We start by applying classical results from random graph theory to show that a large variety of deterministic and random P2P graphs almost surely (i.e., with probability 1-o(1)) remain connected under random failure if and only if they have no isolated nodes. This simple, yet powerful, result subsequently allows us to derive in closed-form the probability that a P2P network develops isolated nodes, and therefore partitions, under both types of node failure. We finish the paper by demonstrating that our models match simulations very well and that dynamic P2P systems are extremely resilient under node churn as long as the neighbor replacement delay is much smaller than the average user lifetime.\",\n \"Title: Long-time dynamics of 2d double-diffusive convection: analysis and/of numerics\\nYear: 2015\\n\\nAbstract: We consider a two-dimensional model of double-diffusive convection and its time discretisation using a second-order scheme (based on backward differentiation formula for the time derivative) which treats the non-linear term explicitly. Uniform bounds on the solutions of both the continuous and discrete models are derived (under a timestep restriction for the discrete model), proving the existence of attractors and invariant measures supported on them. As a consequence, the convergence of the attractors and long time statistical properties of the discrete model to those of the continuous one in the limit of vanishing timestep can be obtained following established methods.\",\n \"Title: An efficient and long-time accurate third-order algorithm for the Stokes–Darcy system\\nYear: 2016\\n\\nAbstract: Abstract A third-order in time numerical IMEX-type algorithm for the Stokes–Darcy system for flows in fluid saturated karst aquifers is proposed and analyzed. A novel third-order Adams–Moulton scheme is used for the discretization of the dissipative term whereas a third-order explicit Adams–Bashforth scheme is used for the time discretization of the interface term that couples the Stokes and Darcy components. The scheme is efficient in the sense that one needs to solve, at each time step, decoupled Stokes and Darcy problems. Therefore, legacy Stokes and Darcy solvers can be applied in parallel. The scheme is also unconditionally stable and, with a mild time-step restriction, long-time accurate in the sense that the error is bounded uniformly in time. Numerical experiments are used to illustrate the theoretical results. To the authors’ knowledge, the novel algorithm is the first third-order accurate numerical scheme for the Stokes–Darcy system possessing its favorable efficiency, stability, and accuracy properties.\",\n \"Title: Enhanced algorithm for high-dimensional data classification\\nYear: 2016\\n\\nAbstract: Graphical abstractIllustration of the decision hyperplanes generated by TSSVM, MCVSVM, and LMLP on an artificial dataset. Display Omitted HighlightsIn the case of the singularity of the within-class scatter matrix, the drawbacks of both MCVSVM and LMLP are analyzed.A novel algorithm TSSVM is proposed to deal with the high-dimensional data classification task where the within-class scatter matrix is singular.An alternative version of the nonlinear MCVSVM and the nonlinear LMLP are proposed.The nonlinear TSSVM is developed. Minimum class variance support vector machine (MCVSVM) and large margin linear projection (LMLP) classifier, in contrast with traditional support vector machine (SVM), take the distribution information of the data into consideration and can obtain better performance. However, in the case of the singularity of the within-class scatter matrix, both MCVSVM and LMLP only exploit the discriminant information in a single subspace of the within-class scatter matrix and discard the discriminant information in the other subspace. In this paper, a so-called twin-space support vector machine (TSSVM) algorithm is proposed to deal with the high-dimensional data classification task where the within-class scatter matrix is singular. TSSVM is rooted in both the non-null space and the null space of the within-class scatter matrix, takes full advantage of the discriminant information in the two subspaces, and so can achieve better classification accuracy. In the paper, we first discuss the linear case of TSSVM, and then develop the nonlinear TSSVM. Experimental results on real datasets validate the effectiveness of TSSVM and indicate its superior performance over MCVSVM and LMLP.\",\n \"Title: Approximate aggregation for tracking quantiles and range countings in wireless sensor networks\\nYear: 2015\\n\\nAbstract: We consider the problem of tracking quantiles and range countings in wireless sensor networks. The quantiles and range countings are two important aggregations to characterize a data distribution. Let S ( t ) = ( d 1 , ¿ , d n ) denote the multi-set of sensory data that have arrived until time t, which is a sequence of data orderly collected by nodes s 1 , s 2 , ¿ , s k . One of our goals is to continuously track ¿-approximate ¿-quantiles ( 0 ¿ ¿ ¿ 1 ) of S ( t ) for all ¿'s with efficient total communication cost and balanced individual communication cost. The other goal is to track ( ¿ , ¿ ) -approximate range countings satisfying the requirement of arbitrary precision specified by different users. In this paper, a deterministic tracking algorithm based on a dynamic binary tree is proposed to track ¿-approximate ¿-quantiles, whose total communication cost is O ( k / ¿ ¿ log ¿ n ¿ log 2 ¿ ( 1 / ¿ ) ) , where k is the number of the nodes in a network, n is the total number of the data, and ¿ is the user-specified approximation error. For range countings, a Bernoulli sampling based algorithm is proposed to track ( ¿ , ¿ ) -approximate range countings, whose total communication cost is O ( 2 ¿ 2 ln ¿ 2 1 - 1 - ¿ + n c ) , where ¿ is the user-specified error probability, n c is the number of clusters.\",\n \"Title: Energy-efficient resource allocation for OFDMA relay systems with imperfect CSIT\\nYear: 2015\\n\\nAbstract: In this paper, we propose an energy-efficient resource allocation scheme for the downlink of decode-and-forward relay-assisted orthogonal frequency division multiple access systems. The resource allocation is designed based on imperfect channel state information at the transmitter. We jointly optimize the power allocation, data rate allocation, and subcarrier allocation to maximize the system energy efficiency (EE). We formulate the EE problem as a probabilistic mixed non-convex optimization problem, in which the individual power constraints and the outage probability requirements are considered. An iterative algorithm based on bisection method is given to transform the optimization problem into a standard concave form. Also, we consider a proportional fairness design for the EE maximization problem. Simulation results illustrate the effectiveness of the proposed algorithm.\",\n \"Title: Multiple Base Stations Cooperation: A Novel Clustering Algorithm and Its Energy Efficiency.\\nYear: 2016\\n\\nAbstract: Multiple base stations (BSs) cooperation can effectively reduce the inter-cell interference and especially improve the performance of the cell-edge users, which has been regarded as an important technology in future wireless communication system. All BSs full cooperation is unaffordable for system overhead, so how to partition the BSs in the system into different clusters to cooperate with a low complexity is a challenging issue. In this paper, a novel dynamic clustering algorithm for multiple BSs cooperation in downlink is proposed, and system energy efficiency (EE) is investigated. Firstly, with equal power allocation per symbol and per antenna equal power constraint, the formulas of spectral efficiency (SE) and EE for the case of ideal transmit and the case of actual transmit are derived, respectively. In addition, a novel dynamic clustering algorithm based on channel norm is presented. By calculating the mutual interference matrix according to channel norm, for each clustering judgment, the BS which has the biggest element in the present interference matrix is selected as the leader BS. Then the rest BSs which have the larger interference coefficient with the leader BS are chosen to joint the cluster until the cluster is formed. The computational complexity of the proposed algorithm is analyzed. Simulation results show that EE of the proposed algorithm is better than that of the static clustering one and slightly worse than that of the decentralized algorithm but with a lower complexity.\",\n \"Title: Kansei engineering, humans and computers: efficient dynamic programming algorithms for combinatorial food packing problems\\nYear: 2011\\n\\nAbstract: The packing system performs an operation of choosing a subset I′ from the set of I of the current n items to produce a package of foods. By repeating the packing operation, it produces a large number of packages one by one. The primary objective is to choose a subset I′ so that the total weight of chosen items is as close to a specified target weight T as possible. We additionally try to maximise the total priority of chosen items as the second objective so that items with longer durations in hoppers are preferably chosen. We show that the combinatorial food packing problem can be solved in O(nT) time if all input data are integral.\",\n \"Title: Altered Structural And Functional Feature Of Striato-Cortical Circuit In Benign Epilepsy With Centrotemporal Spikes\\nYear: 2015\\n\\nAbstract: Benign epilepsy with centrotemporal spikes (BECT) is the most common form of childhood idiopathic focal epilepsy syndrome. We investigated quantitative evidence regarding brain morphology and functional connectivity features to provide insight into the neuroanatomical foundation of this disorder, using high resolution T1-weighted magnetic resonance imaging (MRI) and resting state functional MRI in 21 patients with BECT and in 20 healthy children. The functional connectivity analysis, seeded at the regions with altered gray-matter (GM) volume in voxel-based morphometry (VBM) analysis, was further performed. Then, the observed structural and functional alteration were investigated for their association with the clinical and behavior manifestations. The increased GM volume in the striatum and fronto-temporo-parietal cortex (striato-cortical circuit) was observed in BECT. The decreased connections were found among the motor network and frontostriatal loop, and between the default mode network (DMN) and language regions. Additionally, the GM of striatum was negatively correlated with age at epilepsy onset. The current observations may contribute to the understanding of the altered structural and functional feature of striato-cortical circuit in patients with BECT. The findings also implied alterations of the motor network and DMN, which were associated with the epileptic activity in patients with BECT. This further suggested that the onset of BECT might have enduring structural and functional effects on brain maturation.\",\n \"Title: The impact of node velocity diversity on mobile opportunistic network performance\\nYear: 2015\\n\\nAbstract: Mobile opportunistic network is a special kind of mobile ad hoc networks, in which nodes can communicate and interact with each other without a fixed communication infrastructure. Data dissemination between nodes utilizes a store-carry-forward paradigm. In this paper, we explore the impact of node velocity diversity on the performance of mobile opportunistic networks while keeping the average velocity of nodes consistent with each other. The numerical results indicate that greater node velocity diversity always implies longer average communication and the smaller number of communications within the constant total communication time. Thus, it is important to improve the performance of mobile opportunistic networks by adjusting the velocity diversity in response to the requirement of the network and in order to make full use of communication resources. In particular, we construct mathematical models to analyze node contact times and link numbers. Lastly, we verify the correctness of models and theories we proposed by using the Opportunistic Network Environment simulator.\",\n \"Title: Authenticating multi-dimensional query results in outsourced database.\\nYear: 2016\\n\\nAbstract: In the outsourced database model, the third-party server provides query services to users on behalf of the data owner. However, the service provider may be unreliable or susceptible to attacks. The service provider can also produce inauthentic or incomplete query results. An authentication scheme for multi-dimensional data is proposed in the present study to investigate this problem. The authors i...\",\n \"Title: A Novel Page Ranking Algorithm Based On Triadic Closure And Hyperlink-Induced Topic Search\\nYear: 2015\\n\\nAbstract: The Hyperlink-Induced Topic Search (HITS) algorithm developed by Jon Kleinberg made use of the link structure of the web pages on the Web in order to discover and rank web pages being relevant to a particular topic. However it only took account of the hyperlink structure, while completely excluded contents of web pages, and it ignored the fact that degrees of the importance of many hyperlinks on the Web may be different. In this paper, to overcome the topic drifts, we proposed a novel page ranking algorithm combining the hyperlink with the triadic closure theory by considering fully the Vector Space Model (VSM) and the TrustRank algorithm. The method firstly computed the relevance between two randomly arbitrary web pages based on web page topic similarity and common reference degree. Then, by using that model as a point of reference, a new adjacency matrix was constructed to iteratively calculate the authority and hub values of web pages. Next, we calculated the trust-degree for each web page in the basic set by the trust-score algorithm. Finally, the score for each web page is computed by linearly merging the authority and the trust-degree. In our experiments, we used five classic HITS-based algorithms to compare with our proposed page ranking algorithm-PCTHITS (Web Page Topic Similarity, Common Reference Degree, Trust-degree) algorithm. The experimental results demonstrated that our proposed algorithm outperform the other four classic improved algorithms and HITS algorithm.\",\n \"Title: Novel adaptive high-performance and nonlinear filtering algorithm for mixed noise removal\\nYear: 2012\\n\\nAbstract: A novel adaptive high-performance and nonlinear filtering algorithm (AHPNFA) is proposed for the removal of mixed noise from corrupted images. This algorithm contains two stages: noise determining and noise removing. In the first stage, for each filtering window of the processed image, the center pixel and its nearest neighbors are modeled as a statistical variable. By exploiting Chebyshev's theorem, the fuzzy mean process is used to estimate adaptively the detection parameters that are required in determining whether the current pixel is corrupted or not. In the second stage, the Radon transform is performed to determine the texture direction probability density distributions of local areas of images, then using the texture direction probability density distributions and the local features of the image remove the noisy pixels. To demonstrate the advantages, the proposed AHPNFA is compared with the other test filters both visually and quantitatively. Simulation results show that the proposed AHPNFA has better values in important evaluation metrics; in particular, the computational complexity of the AHPNFA is about five to 11 times lower than the other test filters used in the comparison, therefore, the proposed AHPNFA has better performances. (C) 2012 SPIE and IS&T. [DOI: 10.1117/1.JEI.21.2.023005]\",\n \"Title: Mobility-aware routing in delay tolerant networks\\nYear: 2015\\n\\nAbstract: Delay tolerant networks (DTNs) make use of opportunistic encounters of nodes for communication. The characteristics of high mobility of nodes, frequent link variation and long communication delays in DTNs result in an absence of an instantaneous end-to-end path from any source to a destination, making routing a challenge in DTNs. To deal with this issue, a lot of routing schemes have been proposed, in which future contacts of nodes are predicted based on node mobility traces and contact information. However, the previous works did not consider the spatial information of nodes, such as dwelling time at a location, and the transitivity of contacts in the prediction process of future encounter opportunities of nodes. In this paper, a novel mobility prediction-based routing (MPR) scheme is proposed for DTNs, in which the spatial information of nodes and contact transitivity are both taken into account. Specifically, a time-homogeneous semi-Markov process model is proposed to describe node mobility. By employing the semi-Markov model, we formulate the probability of a node destined to an area subject to the remaining time period constraint. The simulation results show that the proposed MPR scheme substantially improves delivery ratio and reduces delivery latency compared with traditional DTN routing schemes.\",\n \"Title: Energy-Efficient Resource Allocation In Multi-Cell Ofdma Systems With Imperfect Csi\\nYear: 2015\\n\\nAbstract: In this paper, a resource allocation algorithm for maximizing energy efficiency (EE) is studied in multi-cell orthogonal frequency division multiple access (OFDMA) wireless networks. The resource allocation is designed based on imperfect channel state information (CSI). We formulate the resource allocation problem as a mixed non-convex probabilistic optimization problem. The user scheduling, data rate adaptation and power allocation are jointly designed to maximize the system EE, under the maximum transmitted power constraint and the outage probability constraint. An iterative algorithm is proposed in which the EE keeps improving until algorithm convergence. In each iteration, the energy-efficient power allocation optimization problem is solved by a lower bound problem and a parameterized transformation. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm.\",\n \"Title: Modeling Propagation Dynamics and Developing Optimized Countermeasures for Rumor Spreading in Online Social Networks\\nYear: 2015\\n\\nAbstract: The spread of rumors in Online Social Networks (OSNs) poses great challenges to the social peace and public order. It is imperative to model propagation dynamics of rumors and develop corresponding countermeasures. Most of the existing works either overlook the heterogeneity of social networks or do not consider the cost of countermeasures. Motivated by these issues, this paper proposes a heterogeneous network based epidemic model that incorporates both the network heterogeneity and various countermeasures. Through analyzing the existence and stability of equilibrium solutions of the proposed ODE (Ordinary Differential Equation) system, the critical conditions that determine whether a rumor continuously propagates or becomes extinct are derived. Moreover, we concern about the cost of the main two types of countermeasures, i.e., Blocking rumors at influential users and spreading truth to clarify rumors. Employing the Pontryagin's maximum principle, we obtain the optimized countermeasures that ensures a rumor can become extinct at the end of an expected time period with lowest cost. Both the critical conditions and the optimized countermeasures provide a real-time decision reference to restrain the rumor spreading. Experiments based on Digg2009 dataset are conducted to evaluate the effectiveness of the proposed dynamic model and the efficiency of the optimized countermeasures.\",\n \"Title: A Double Pulse Control Strategy For Misinformation Propagation In Human Mobile Opportunistic Networks\\nYear: 2015\\n\\nAbstract: Mobile Opportunistic Networks (MONs) are effective solutions to uphold communications in the situations where traditional communication networks are unavailable. However, MONs can be abused to disseminate misinformation causing undesirable effects in public. To prevent misinformation from propagating, we first propose a formal model to formulate the process of misinformation propagation based on the ordinary differential equation. Secondly, we explore a general framework to describe the random mobility of nodes, and derive a new contact rate between nodes. Thirdly, we propose a double pulse control strategy of vaccination and treatment for inhibiting misinformation propagation. Moreover, a novel pulse control model of misinformation propagation is developed based on the impulsive differential equation. Finally, through the derivation and stability analysis of a misinformation-free period solution of the proposed model, we obtain a threshold upon which misinformation dies out. The simulation results validate our theoretical analysis.\",\n \"Title: Spacial Mobility Prediction Based Routing Scheme in Delay/Disruption-Tolerant Networks\\nYear: 2014\\n\\nAbstract: Routing is a challenging issue in Delay/Disruption Tolerant Networks (DTNs) due to the characteristics of high mobility of nodes and high dynamicity of network topology. The previous works did not consider the spacial information of nodes, such as dwelling time at a location when predicting the future contact of two nodes. In this paper, a novel Spacial Mobility Prediction based Routing (SMPR) scheme is proposed for DTNs, in which the spacial information of nodes and contact transitivity are both taken into account. Specifically, a time homogeneous semi-Markov process model is proposed to describe the mobility of nodes. The simulation results show that the proposed SMPR scheme substantially improves delivery ratio and reduces delivery latency compared with traditional DTN routing schemes.\",\n \"Title: FakeMask: A Novel Privacy Preserving Approach for Smartphones.\\nYear: 2016\\n\\nAbstract: Users can enjoy personalized services provided by various context-aware applications that collect users' contexts through sensor-equipped smartphones. Meanwhile, serious privacy concerns arise due to the lack of privacy preservation mechanisms. Currently, most mechanisms apply passive defense policies in which the released contexts from a privacy preservation system are always real, leading to a g...\",\n \"Title: User-Centric Cross-Tier Base Station Clustering and Cooperation in Heterogeneous Networks: Rate Improvement and Energy Saving.\\nYear: 2016\\n\\nAbstract: Heterogeneous cellular networks (HetNets) are to be deployed for future wireless communication to meet the ever-increasing mobile traffic demand. However, the dense and random deployment of small cells and their uncoordinated operation raise important concerns about various costs issues, among which notably is energy efficiency. Base station (BS) cooperation is set to play a key role in managing interference in HetNets. In this paper, we consider BS cooperation in the downlink HetNets where BSs from different tiers within the respective cooperative clusters jointly transmit the same data to a typical user, and in particular focus on the optimization of the energy efficiency performance. First, based on a proposed clustering model, we derive the spectral efficiency using tools from stochastic geometry. Furthermore, we formulate a power minimization problem with a minimum spectral efficiency constraint and derive the optimal received signal strength (RSS) thresholds under certain approximation. Building upon these results, we could address the problem of how to design appropriate RSS thresholds, taking into account the tradeoff between spectral efficiency and energy efficiency. Simulations show that the proposed clustering model is more energy-saving than the geometric clustering model, and deploying a multitier HetNet is significantly more energy-saving compared to a macro-only network.\",\n \"Title: Principles of the Complete Voronoi Diagram Localization.\\nYear: 2016\\n\\nAbstract: This paper explores the rationale behind the Complete Voronoi Diagram (CVD) Localization, which is a computational geometry approach to the wireless network localization. Our work consists mainly of three parts. The first part focuses on the analysis of CVD's mathematical properties. We characterize CVD's central tendency as the mirror-image distribution and provide mathematical formula for its probability density function. We also provide a closed formula for the relationship between CVD's vertices, chords, and faces, the average chord length, and the average edge number of a CVD polygon. And, the expressions for the average overall and local positioning error are also provided. Based upon these findings, we show that the convergence speed for a CVD based localization scheme is quadratic, and the optimal time and space complexities are (n 2 ) and (n), respectively. The second part proposes a novel approach, called Polling, which utilizes the concept of the Error Region, to further improve the accuracy. Polling, in theory, enables us to make use of the topology information with the quantity up to O(n 4 ) provided by CVD for localization, while a conventional CVD scheme can use only O(1) such information. The third part, through simulations, shows how to use the quasi Analog-to-Digital Conversion (qADC) strategy to handle signal errors. Combined with Polling and qADC, a CVD scheme can provide a simple, robust, and powerful solution to the wireless network localization. Some of our findings and methods may also contribute to the field of computational geometry its own.\",\n \"Title: Fast 3D-Object Modeling with Kinect and Rotation Platform.\\nYear: 2015\\n\\nAbstract: High-fidelity reconstruction of complete objects is known as a particularly challenging problem. In this paper, we provide a system for object modeling with Kinect and rotation platform. Our modeling solution is divided into three steps: (1) system calibration, (2) Point cloud real time registration,(3) Mesh surface reconstruction and automatic texture mapping. We propose a easy-to-use calibration method for the first step, and based on the calibration result, a automatic texture-independent 3D point clouds registration method is presented. Finally, triangulate meshing and automatic texture mapping technique are used to recreate complete mesh model from the integrated point clouds. Our system is validated by the modeling of several real-world objects, and all the results show its effectiveness.\",\n \"Title: Exploiting Spectrum Availability And Quality In Routing For Multi-Hop Cognitive Radio Networks\\nYear: 2016\\n\\nAbstract: Cognitive radio networks (CRNs) are considered as a promising solution to the problem of spectrum under utilization and artificial radio spectrum scarcity. The paradigm of dynamic spectrum access allows secondary users (SUs) to utilize wireless spectrum resources which belong to primary users (PUs) with minimal interference to PUs. Due to the dynamic spectrum availability and quality, routing for SUs in multi-hop CRNs is a challenge. In this paper, we introduce novel routing metrics that estimate both the future spectrum availability and the average transmission time. Then, we propose two routing algorithms for multi-hop CRNs that attempt to reduce the probability of spectrum handoff and rerouting upon PU's arrival. Finally, we conduct simulations, whose results show that our proposed algorithms lead to a significant performance improvement over the reference algorithm.\",\n \"Title: Truthful Incentive Mechanisms for Social Cost Minimization in Mobile Crowdsourcing Systems.\\nYear: 2016\\n\\nAbstract: With the emergence of new technologies, mobile devices are capable of undertaking computational and sensing tasks. A large number of users with these mobile devices promote the formation of the Mobile Crowdsourcing Systems (MCSs). Within a MCS, each mobile device can contribute to the crowdsourcing platform and get rewards from it. In order to achieve better performance, it is important to design a mechanism that can attract enough participants with mobile devices and then allocate the tasks among participants efficiently. In this paper, we are interested in the investigation of tasks allocation and price determination in MCSs. Two truthful auction mechanisms are proposed for different working patterns. A Vickrey-Clarke-Groves (VCG)-based auction mechanism is proposed to the continuous working pattern, and a suboptimal auction mechanism is introduced for the discontinuous working pattern. Further analysis shows that the proposed mechanisms have the properties of individual rationality and computational efficiencies. Experimental results suggest that both mechanisms guarantee all the mobile users bidding with their truthful values and the optimal maximal social cost can be achieved in the VCG-based auction mechanism.\",\n \"Title: An efficient privacy preserving data aggregation approach for mobile sensing.\\nYear: 2016\\n\\nAbstract: The advances in sensing capabilities of smartphones give rise to a variety of mobile participatory sensing applications that collect users' personal data. Because of the existence of both sensitive, private personal data, and untrusted aggregator, serious privacy concerns on users arise. Currently, existing privacy preserving data collection methods either require bidirectional communications between an untrusted aggregator and mobile users in every aggregation period, or have high computation or communication overhead. To address these problems, we propose an efficient data aggregation approach by which an untrusted aggregator in mobile sensing can collect the statistics over the data contributed by multiple mobile users, while supporting privacy preservation of each user and data integrity verification. In this approach, information hiding and homomorphic encryption are applied to guarantee the data privacy of mobile users. In detail, a breadth-first search tree is first constructed at the initial phase among the mobile users, and then the original datum of each user is perturbed among its neighbors in ciphertext space by using information hiding and homomorphic encryption. The evaluations of our approach show that our protocol requires lower communication and computation overhead and thus more feasible for the computation constrained mobile devices. Copyright © 2016 John Wiley & Sons, Ltd.\",\n \"Title: Computational models and optimal control strategies for emotion contagion in the human population in emergencies.\\nYear: 2016\\n\\nAbstract: Emotions play an important role in the decision-making of individuals. Emotional contagion has an influence on individual and group-level behaviors. Particularly, the contagion of negative emotions like panic emotions may result in devastating consequences in the human population in emergencies. This work develops novel computational models of emotion contagion and solves the optimal control problem of emotion contagion in the human population in emergencies. Firstly, by introducing a concept of latent state and considering complicated interactions among individuals, we develop a novel conceptual model of emotion contagion, and further establish a computational model for describing the dynamics of emotion contagion, called the susceptible-latent-infectious-recovered-susceptible (SLIRS) model. Secondly, by considering vaccination, quarantine and treatment as control measures, we expand the SLIRS model into a controlled SLIRS model, and formulate the control problem of emotion contagion as an optimal control problem, so that the total costs of inhibiting emotion contagion are minimized. Finally, we theoretically discuss the existence and uniqueness of the solution of the controlled SLIRS model, and further derive an optimal control solution of the controlled SLIRS model. The simulation results on the synthesis dataset and the real trace dataset show that the optimal control strategies have significant impact on emotion contagion. Especially, the optimal control strategy with a mixture of vaccination, quarantine and treatment can significantly decrease the scale of the outbreak of negative emotions, and incur the lowest total costs of inhibiting emotion contagion. This enables the optimal decision-making for inhibiting emotion contagion under the consideration of limited resources in the human population in emergencies. Hence, this work will make contributions to crisis management and crowd evacuation in emergencies.\",\n \"Title: A Social Motivation-aware Mobility Model for Mobile Opportunistic Networks.\\nYear: 2016\\n\\nAbstract: In mobile opportunistic networks (MONs), human-carried mobile devices such as PDAs and smartphones, with the capability of short range wireless communications, could form various intermittent contacts due to the mobility of humans, and then could use the contact opportunity to communicate with each other. The dynamic changes of the network topology are closely related to the human mobility patterns. In this paper, we propose a social motivation-aware mobility model for MONs, which explains the basic laws of human mobility from the psychological point of view. We analyze and model social motivations of human mobility mainly in terms of expectancy value theory and affiliation motivation. Furthermore, we introduce a new concept of geographic functional cells, which not only incorporates the influence of geographical constraints on human mobility but also simplifies the complicated configuration of simulation areas. Lastly, we validate our model by simulating three real scenarios and comparing it with reality traces and other synthetic traces. The simulation results show that our model has a better match in the performance evaluation when applying social-based forwarding protocols like BUBBULE.\",\n \"Title: Higher-Load Data Transmitting in Opportunistic Networks Based on Probability Analysis of Communicating Capabilities\\nYear: 2016\\n\\nAbstract: Opportunistic Network has become an international hotspot in according with the popularity of various mobile intelligent terminals. But the nodes with limited communication capabilities cannot satisfy the growing of large content data transmission. Aim to these issues, we propose a novel communication capacity calculation model of Opportunistic Network based on the classical Random Direction mobile model. We observe that different size of fragments in large content represents different delivery delays. Considering that the large content are always the multimedia data, it would necessarily produce additional head-part of every fragment, and this will affect the whole overhead of network. We define the restrain facts model of overhead and put forward an optimal fragment size algorithm. Finally, we designed and evaluated the methods and algorithms in simulate circumstance of Opportunistic Networks. The experiments results show that the average value of contact duration and total times of contacts analyzed from logs are all in according with the contact duration expectation and contact times calculated from the model. The optimal size of fragment is located at the well position in the proper range of fragment size.\",\n \"Title: Cost-Efficient Strategies for Restraining Rumor Spreading in Mobile Social Networks\\nYear: 2017\\n\\nAbstract: With the popularity of mobile devices, mobile social networks (MSNs) have become an important platform for information dissemination. However, the spread of rumors in MSNs present a massive social threat. Currently, there are two kinds of methods to address this: blocking rumors at influential users and spreading truth to clarify rumors. However, most existing works either overlook the cost of var...\",\n \"Title: A social activity and physical contact-based routing algorithm in mobile opportunistic networks for emergency response to sudden disasters.\\nYear: 2017\\n\\nAbstract: Sudden disasters such as earthquake, flood and hurricane necessitate the employment of communication networks to carry out emergency response activities. Routing has a significant impact on the functionality, performance and flexibility of communication networks. In this article, the routing problem is studied considering the delivery ratio of messages, the overhead ratio of messages and the average delay of messages in mobile opportunistic networks MONs for enterprise-level emergency response communications in sudden disaster scenarios. Unlike the traditional routing methods for MONS, this article presents a new two-stage spreading and forwarding dynamic routing algorithm based on the proposed social activity degree and physical contact factor for mobile customers. A new modelling method for describing a dynamic evolving process of the topology structure of a MON is first proposed. Then a multi-copy spreading strategy based on the social activity degree of nodes and a single-copy forwarding strategy based on the physical contact factor between nodes are designed. Compared with the most relevant routing algorithms such as Epidemic, Prophet, Labelled-sim, Dlife-comm and Distribute-sim, the proposed routing algorithm can significantly increase the delivery ratio of messages, and decrease the overhead ratio and average delay of messages.\",\n \"Title: A novel approach for inhibiting misinformation propagation in human mobile opportunistic networks.\\nYear: 2017\\n\\nAbstract: Mobile Opportunistic Networks (MONs) are effective solutions to uphold communications in the situations where traditional communication networks are unavailable. In MONs, messages can be disseminated among mobile nodes in an epidemic and delay-tolerant manner. However, MONs can be abused to disseminate misinformation causing undesirable effects in the general public, such as panic and misunderstanding. To deal with this issue, we first propose a formal model to formulate the process of misinformation propagation in MONs, considering human psychological behaviors. Secondly, we explore a general framework to describe the random node mobility, and derive a new contact rate between nodes, which is closely related to mobility properties of nodes. Thirdly, we propose a novel approach based on vaccination and treatment strategies for inhibiting misinformation propagation in human MONs. Moreover, a novel pulse control model of misinformation propagation is developed. Finally, through the derivation and stability analysis of a misinformation-free period solution of the proposed model, we obtain a threshold upon which misinformation dies out in a human MON. The extensive simulation results validate our theoretical analysis.\",\n \"Title: Priority queue based polling mechanism on seismic equipment cluster monitoring.\\nYear: 2017\\n\\nAbstract: This paper proposes a passive monitoring system model suitable for seismic observation equipment cluster. Through detailed analysis and design of two key technologies affecting the performance of the system under this model, we pose the priority queue based (PQB) polling mechanism on the cluster node monitoring and the volatility-removed (VR) fault alarm mechanism. New polling mechanism initializes priorities of cluster nodes according to the importance of them, then put them into the polling queue according to the priority order, nodes with same priority follow FCFS algorithm, thus solving problems that important cluster nodes be monitored first. A formula judging whether equipment is in the fluctuant state is given by VR fault alarm mechanism, which improves the accuracy of the monitoring results. Finally, we build an experimental platform to analyze the data of PQB polling and VR warning mechanisms, the conclusion shows that the PQB increases the count of polling nodes than FCFS polling mechanism and VR is more close to the actual fault results than normal alarm mechanism. Furthermore, PQB and VR mechanisms have no significant impact on server performance.\",\n \"Title: Spectrum-Availability Based Routing for Cognitive Sensor Networks.\\nYear: 2017\\n\\nAbstract: With the occurrence of Internet of Things (IoT) era, the proliferation of sensors coupled with the increasing usage of wireless spectrums especially the ISM band makes it difficult to deploy real-life IoT. Currently, the cognitive radio technology enables sensors transmit data packets over the licensed spectrum bands as well as the free ISM bands. The dynamic spectrum access technology enables secondary users (SUs) access wireless channel bands that are originally licensed to primary users. Due to the high dynamic of spectrum availability, it is challenging to design an efficient routing approach for SUs in cognitive sensor networks. We estimate the spectrum availability and spectrum quality from the view of both the global statistical spectrum usage and the local instant spectrum status, and then introduce novel routing metrics to consider the estimation. In our novel routing metrics, one retransmission is allowed to restrict the number of rerouting and then increase the routing performance. Then, the related two routing algorithms according to the proposed routing metrics are designed. Finally, our routing algorithms in extensive simulations are implemented to evaluate the routing performance, and we find that the proposed algorithms achieve a significant performance improvement compared with the reference algorithm.\",\n \"Title: Design and Testing of a Parallel Manipulator for Space Micro-vibration Simulation.\\nYear: 2017\\n\\nAbstract: A micro-vibration shaking platform is required for performance testing of sensitive instruments in a micro-vibration environment on-board spacecraft before launch. In this study, a parallel manipulator is designed, which can reproduce 6-DOF space micro-vibrations. The important parts of the manipulator are optimized. Controlling the parallel manipulator is based on transfer function. The control principle and the transfer function testing are introduced. Because of the small structural damping coefficient of the system, the transfer function is simplified from a complex matrix to real matrix. Since the parallel manipulator be-haves slightly nonlinearly, an iterative control strategy is used to approach the desired acceleration step by step. The results from microvibrations testing show that the parallel manipulator can simulate 6DOF space micro-vibrations and the iterative control strategy has better precision for the micro-vibrations control.\",\n \"Title: Uniquely solvable and energy stable decoupled numerical schemes for the Cahn---Hilliard---Stokes---Darcy system for two-phase flows in karstic geometry\\nYear: 2017\\n\\nAbstract: We propose and analyze two novel decoupled numerical schemes for solving the Cahn---Hilliard---Stokes---Darcy (CHSD) model for two-phase flows in karstic geometry. In the first numerical scheme, we explore a fractional step method (operator splitting) to decouple the phase-field (Cahn---Hilliard equation) from the velocity field (Stokes---Darcy fluid equations). To further decouple the Stokes---Darcy system, we introduce a first order pressure stabilization term in the Darcy solver in the second numerical scheme so that the Stokes system is decoupled from the Darcy system and hence the CHSD system can be solved in a fully decoupled manner. We show that both decoupled numerical schemes are uniquely solvable, energy stable, and mass conservative. Ample numerical results are presented to demonstrate the accuracy and efficiency of our schemes.\",\n \"Title: Minimum class variance support vector ordinal regression.\\nYear: 2017\\n\\nAbstract: The support vector ordinal regression (SVOR) method is derived from support vector machine and developed to tackle the ordinal regression problems. However, it ignores the distribution characteristics of the data. In this paper, we propose a novel method to handle the ordinal regression problems. This method is referred to as minimum class variance support vector ordinal regression (MCVSVOR). In contrast with SVOR, MCVSVOR explicitly takes into account the distribution of the categories and achieves better generalization performance. Moreover, the problem of MCVSVOR can be transformed into one of SVOR. Thus, the existing software of SVOR can be used to solve the problem of MCVSVOR. In the paper, we first discuss the linear case of MCVSVOR and then develop the nonlinear MCVSVOR through using the kernelization trick. The comprehensive experiment results show that the proposed method is effective and can achieve better generalization performance in contrast with SVOR.\",\n \"Title: Convergence analysis and error estimates for a second order accurate finite element method for the Cahn-Hilliard-Navier-Stokes system.\\nYear: 2017\\n\\nAbstract: In this paper, we present a novel second order in time mixed finite element scheme for the Cahn–Hilliard–Navier–Stokes equations with matched densities. The scheme combines a standard second order Crank–Nicolson method for the Navier–Stokes equations and a modification to the Crank–Nicolson method for the Cahn–Hilliard equation. In particular, a second order Adams-Bashforth extrapolation and a trapezoidal rule are included to help preserve the energy stability natural to the Cahn–Hilliard equation. We show that our scheme is unconditionally energy stable with respect to a modification of the continuous free energy of the PDE system. Specifically, the discrete phase variable is shown to be bounded in \\\\(\\\\ell ^\\\\infty \\\\left( 0,T;L^\\\\infty \\\\right) \\\\) and the discrete chemical potential bounded in \\\\(\\\\ell ^\\\\infty \\\\left( 0,T;L^2\\\\right) \\\\), for any time and space step sizes, in two and three dimensions, and for any finite final time T. We subsequently prove that these variables along with the fluid velocity converge with optimal rates in the appropriate energy norms in both two and three dimensions.\",\n \"Title: MPLB: A Load Balance Scheme of Joint Resource Scheduling in Heterogeneous Wireless Network\\nYear: 2017\\n\\nAbstract: A user terminal with multi-mode wireless interface is always located its position in the covered area of heterogeneous wireless network (HWN), there are too many algorithms about vertical handover (VHO) of multiple attributes decision making (MADM) network selections about HWN. According the analysis of current applications of wireless service, regular service has been classified into four kinds, including voice, video, small data and big data, and the proportions of wireless video and big data service may acquire an unavailable bandwidth for each individual wireless station, which will lead to a heavy load and a lower satisfaction rate. A multiple properties load balance (MPLB) scheme is proposed to solve this joint resource scheduling(JRS) problem properly, MPLB scheme first gave an enhanced architecture including the JSR sub-layer, then model of MPLB is established from the candidate wireless network, five aggregated network performance properties have been defined mathematically, the candidate of best grey relational coefficients (GRC) of grey relational analysis(GRA) algorithm is optimally selected as the final executable scheme, after the description of a general flowchart of MPLB scheme. The simulation results proved the MPLB scheme has a more stable load balance effects than those of VHO, so did most users of MPLB gain higher satisfaction rate, slightly different with the four kinds of service. It can be concluded theoretically that the MPLB scheduling scheme could achieve both the load balance on the service providers side and the increased quality of experience of satisfaction rate on the wireless user side, which would bring out some new thoughts in the future user centric network.\",\n \"Title: CPC: A novel content popularity compensation algorithm for intelligent wireless router in user centric network\\nYear: 2017\\n\\nAbstract: User centric network (UCN) brought a new concept of all routers to be intelligent and definable, intelligent wireless terminals implement more video online service than general webpage exploring service, in the time of content is the king, how to provide a best user experience for the video content user under intelligent wireless routers(IWR) is a key focus in the current research of user centric network. This paper proposed a scheme of intelligent pipe between Policy server and IWR, and designed a novel content popularity compensation (CPC) algorithm in user centric network framework, the IWR obtained the user attributes and video content popularity, used the parameter of content popularity compensation index (CPI) to integrate the classified user weight (CUW) and content popularity level (CPL), the modified satisfaction degree (MSD) was designed to replace of the general index of user satisfaction degree, such as linear satisfaction degree (LSD) and simple logarithmic satisfaction (SLS). The scheduling rule was to get a maximized system MSD, and the measurement of user average satisfaction (UAS) was the evaluation standard of CPC. The simulations results showed that the CPC got the better performance than that of routine algorithms, such as max-min fairness (MMF) and Utility function (ULF), the CPC algorithm could push on the intelligent wireless router in smart home and bring a novel video content quality of experience (QoE) of future wireless video online users.\",\n \"Title: A social-aware probabilistic routing approach for mobile opportunistic social networks.\\nYear: 2017\\n\\nAbstract: In mobile opportunistic social networks (MOSNs), mobile users move around and conduct message transmission by using their portable devices without the support of communication infrastructures, in which routing is a challenge due to high connection intermittency and node mobility. The current routing schemes for MOSNs only focus on the improvement of cost-effective delivery by using the characteristics of users' interests or mobility. In this paper, we propose a novel routing approach for MOSNs in which the probabilistic and social-aware strategies are combined and the multiple-copy policy is adopted. We first model an MOSN into some overlapping regions and then propose 2 region-related centrality degrees related to users' social characteristics with the consideration of users' centrality, mobility, and interactions among users. According to the definition of centrality degrees, we design a social-aware probabilistic routing approach in which a message replica control policy is applied to allow a user with higher encounter probability to the destination and the user could obtain more message replicas. The simulation results show that the proposed approach outperforms the previous routing algorithms in terms of delivery ratio and overhead ratio.\",\n \"Title: An Edge Correlation Based Differentially Private Network Data Release Method.\\nYear: 2017\\n\\nAbstract: Differential privacy (DP) provides a rigorous and provable privacy guarantee and assumes adversaries' arbitrary background knowledge, which makes it distinct from prior work in privacy preserving. However, DP cannot achieve claimed privacy guarantees over datasets with correlated tuples. Aiming to protect whether two individuals have a close relationship in a correlated dataset corresponding to a weighted network, we propose a differentially private network data release method, based on edge correlation, to gain the tradeoff between privacy and utility. Specifically, we first extracted the Edge Profile (PF) of an edge from a graph, which is transformed from a raw correlated dataset. Then, edge correlation is defined based on the PFs of both edges via Jenson-Shannon Divergence (JS-Divergence). Secondly, we transform a raw weighted dataset into an indicated dataset by adopting a weight threshold, to satisfy specific real need and decrease query sensitivity. Furthermore, we propose epsilon-correlated edge differential privacy (CEDP), by combining the correlation analysis and the correlated parameter with traditional DP. Finally, we propose network data release (NDR) algorithm based on the epsilon-CEDP model and discuss its privacy and utility. Extensive experiments over real and synthetic network datasets show the proposed releasing method provides better utilities while maintaining privacy guarantee.\",\n \"Title: An Efficient Context-Aware Privacy Preserving Approach for Smartphones.\\nYear: 2017\\n\\nAbstract: With the proliferation of smartphones and the usage of the smartphone apps, privacy preservation has become an important issue. The existing privacy preservation approaches for smartphones usually have less efficiency due to the absent consideration of the active defense policies and temporal correlations between contexts related to users. In this paper, through modeling the temporal correlations among contexts, we formalize the privacy preservation problem to an optimization problem and prove its correctness and the optimality through theoretical analysis. To further speed up the running time, we transform the original optimization problem to an approximate optimal problem, a linear programming problem. By resolving the linear programming problem, an efficient context-aware privacy preserving algorithm (CAPP) is designed, which adopts active defense policy and decides how to release the current context of a user to maximize the level of quality of service (QoS) of context-aware apps with privacy preservation. The conducted extensive simulations on real dataset demonstrate the improved performance of CAPP over other traditional approaches.\",\n \"Title: Revocable Key-Aggregate Cryptosystem for Data Sharing in Cloud\\nYear: 2017\\n\\nAbstract: AbstractWith the rapid development of network and storage technology, cloud storage has become a new service mode, while data sharing and user revocation are important functions in the cloud storage. Therefore, according to the characteristics of cloud storage, a revocable key-aggregate encryption scheme is put forward based on subset-cover framework. The proposed scheme not only has the key-aggregate characteristics, which greatly simplifies the user’s key management, but also can revoke user access permissions, realizing the flexible and effective access control. When user revocation occurs, it allows cloud server to update the ciphertext so that revoked users can not have access to the new ciphertext, while nonrevoked users do not need to update their private keys. In addition, a verification mechanism is provided in the proposed scheme, which can verify the updated ciphertext and ensure that the user revocation is performed correctly. Compared with the existing schemes, this scheme can not only reduce the cost of key management and storage, but also realize user revocation and achieve user’s access control efficiently. Finally, the proposed scheme can be proved to be selective chosen-plaintext security in the standard model.\",\n \"Title: Resource allocation in OFDMA heterogeneous networks for maximizing weighted sum energy efficiency.\\nYear: 2017\\n\\nAbstract: In this paper, a resource allocation algorithm for maximizing the weighted sum energy efficiency (EE) is investigated in orthogonal frequency division multiple access (OFDMA) heterogeneous networks (Het-Nets). We aim to balance the EE of macro cell and low power nodes by subchannel and power allocations. We formulate the problem as a nonlinear sum-of-ratios programming issue, and guarantee data rate requirements of users by using minimum rate constraints. Due to the nonconvexity of the problem, we develop a heuristic subchannel assignment algorithm, and then solve the power allocation problem by parameterized transformations and a first-order approximation based on an iterative algorithm. Numerical results illustrate the convergence and the effectiveness of the proposed algorithm.\",\n \"Title: Primary and Secondary Social Activity Aware Routing for Cognitive Radio Networks\\nYear: 2016\\n\\nAbstract: In cognitive radio networks (CRNs), efficient spectrum access is challenging and whitespace are necessary for communicating pairs, including Primary Users (PUs) and Secondary Users (SUs). In the existing works, available whitespace is determined by PUs' social activities, which has drawn much attention and been investigated. In reality, SUs need to compete with each other in obtaining accessible whitespace. To the best of our knowledge, the modeling and integration of SUs' social activities have not been considered in real whitespace analysis. Inspired by this motivation, we propose an solution aiming to attaining accessible whitespace, which considers the available whitespace determined by primary activities and the competitions based on secondary activities. Furthermore, we take a spectrum aware routing, including accessible whitespace and routing convergence, as an example to demonstrate the advantage of this proposed solution. The simulation experiments conducted on real world datasets verify the difference between available whitespace and accessible whitespace, and also show the adaptiveness of the proposed algorithm in terms of average delivery ratio and average delay.\",\n \"Title: An on-demand coverage based self-deployment algorithm for big data perception in mobile sensing networks.\\nYear: 2018\\n\\nAbstract: Mobile Sensing Networks have been widely applied to many fields for big data perception such as intelligent transportation, medical health and environment sensing. However, in some complex environments and unreachable regions of inconvenience for human, the establishment of the mobile sensing networks, the layout of the nodes and the control of the network topology to achieve high performance sensing of big data are increasingly becoming a main issue in the applications of the mobile sensing networks. To deal with this problem, we propose a novel on-demand coverage based self-deployment algorithm for big data perception based on mobile sensing networks in this paper. Firstly, by considering characteristics of mobile sensing nodes, we extend the cellular automata model and propose a new mobile cellular automata model for effectively characterizing the spatial–temporal evolutionary process of nodes. Secondly, based on the learning automata theory and the historical information of node movement, we further explore a new mobile cellular learning automata model, in which nodes can self-adaptively and intelligently decide the best direction of movement with low energy consumption. Finally, we propose a new optimization algorithm which can quickly solve the node self-adaptive deployment problem, thus, we derive the best deployment scheme of nodes in a short time. The extensive simulation results show that the proposed algorithm in this paper outperforms the existing algorithms by as much as 40% in terms of the degree of satisfaction of network coverage, the iterations of the algorithm, the average moving steps of nodes and the energy consumption of nodes. Hence, we believe that our work will make contributions to large-scale adaptive deployment and high performance sensing scenarios of the mobile sensing networks.\",\n \"Title: Dynamic Adjustment Strategy of n-Epidemic Routing Protocol for Opportunistic Networks: A Learning Automata Approach.\\nYear: 2017\\n\\nAbstract: In order to improve the energy efficiency of n-Epidemic routing protocol in opportunistic networks, in which a stable end-to-end forwarding path usually does not exist, a novel adjustment strategy for parameter n is proposed using learning atuomata principle. First, nodes dynamically update the average energy level of current environment while moving around. Second, nodes with lower energy level relative to their neighbors take larger n avoiding energy consumption during message replications and vice versa. Third, nodes will only replicate messages to their neighbors when the number of neighbors reaches or exceeds the threshold n. Thus the number of message transmissions is reduced and energy is conserved accordingly. The simulation results show that, n-Epidemic routing protocol with the proposed adjustment method can efficiently reduce and balance energy consumption. Furthermore, the key metric of delivery ratio is improved compared with the original n-Epidemic routing protocol. Obviously the proposed scheme prolongs the network life time because of the equilibrium of energy consumption among nodes.\",\n \"Title: Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers.\\nYear: 2018\\n\\nAbstract: The real-time State Space Representation (SSR) product of the GNSS (Global Navigation Satellite System) orbit and clock is one of the most essential corrections for real-time precise point positioning (PPP). In this work, the performance of current SSR products from eight analysis centers were assessed by comparing it with the final product and the accuracy of real-time PPP. Numerical results showed that (1) the accuracies of the GPS SSR product were better than 8 cm for the satellite orbit and 0.3 ns for the satellite clock; (2) the accuracies of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) SSR product were better than 10 cm for orbit RMS (Root Mean Square) and 0.6 ns for clock STD (Standard Deviation); and (3) the accuracies of the BDS (BeiDou Navigation Satellite System) and Galileo SSR products from CLK93 were about 14.54 and 4.42 cm for the orbit RMS and 0.32 and 0.18 ns for the clock STD, respectively. The simulated kinematic PPP results obtained using the SSR products from CLK93 and CLK51 performed better than those using other SSR products; and the accuracy of PPP based on all products was better than 6 and 10 cm in the horizontal and vertical directions, respectively. The real-time kinematic PPP experiment carried out in Beijing, Tianjin, and Shijiazhuang, China indicated that the SSR product CLK93 from Centre National d'Etudes Spatiales (CNES) had a better performance than CAS01. Moreover, the PPP with GPS + BDS dual systems had a higher accuracy than those with only a GPS single system.\",\n \"Title: Configuration Analysis and Design of a Multidimensional Tele-operator Based on a 3-P(4S) Parallel Mechanism.\\nYear: 2018\\n\\nAbstract: Based on configuration analysis, different types of 3-P(4S) parallel mechanisms are designed and introduced in this paper. Application issues of parallel mechanisms are discussed and a double 3-P(4S) mechanism-based tele-operator is illustrated. Inverse and forward kinematics of the single 3-P(4S) parallel mechanism are derived and solved via MATLAB software; based on it, the workspace of the 3-P(4S) parallel mechanism is investigated. The relationship between the distribution angle of kinematic chain and volume of the workspace is derived, and the shapes of the workspace of single and double 3-P(4S) parallel mechanisms are plotted. A prototype is developed and an interactive simulation system is established based on SolidWorks and LabVIEW software. Testing results indicate that the proposed tele-operator can well perform tele-operation tasks. This research work lays a good basis for performances evaluation and parameter optimization of 3-P(4S) mechanisms. Besides, it provides new ideas for the applications of parallel mechanisms.\",\n \"Title: A Routing Algorithm Based on the Prediction of Node Meeting Location in Opportunistic Networks.\\nYear: 2017\\n\\nAbstract: The opportunistic network is a kind of self-organizing network which makes use of the meeting opportunities created by moving nodes to realize short-distance wireless communication, in which the dynamic characteristics of the network topology often result in low communication efficiency. To improve the efficiency of messages transmission, firstly we combine the Markov model to establish a node location prediction model and a distance prediction and calculation model between nodes respectively in order to accurately predict the location of the nodes at the next moment and calculate the distance between nodes; secondly based on the significance and timelessness of messages, a priority based buffer management strategy is proposed to realize the efficient use of buffer. Finally in this paper we propose an efficient opportunistic network routing algorithm, named LIBR, based on the prediction of node meeting location to forward the messages. Compared with the well-known routing algorithms, the simulation results show that our proposed algorithm can significantly improve the delivery ratio, reduce the overhead ratio and average delay of messages.\",\n \"Title: An Efficient Routing Algorithm Based on Interest Similarity and Trust Relationship Between Users in Opportunistic Networks.\\nYear: 2017\\n\\nAbstract: In opportunistic networks, due to the randomness of node moving and the uncertainty of network topology, it's a challenging issue to establish a complete communication link between the source and the destination node. Fortunately, the \\\"store-carry-forward\\\" strategy can be used to solve this problem. However, such forwarding strategy heavily relies on the cooperation among nodes. Thus, the selection of a proper relay node has a great impact on the performance of the whole network. In this paper, considering the differences between users' interest and the variability of interest with the change of time, firstly, we propose a dynamic update and calculation method of the value of interests, and then establish a calculation model of interest. Secondly, according to the Ebbinghaus forgetting curve and the ability of users to forward messages, we propose a dynamic calculation method of the trust value of users and establish a model for computing trust relationships. Finally, we propose an efficient routing algorithm based on interest similarity and trust relationship (BIST) between users. The simulation results show that our proposed algorithm has better routing performance, and it validates the correctness and validity of our proposed models and algorithm.\",\n \"Title: An Efficient Energy-Aware Probabilistic Routing Approach For Mobile Opportunistic Networks\\nYear: 2018\\n\\nAbstract: Routing is a concerning and challenging research hotspot in Mobile Opportunistic Networks (MONs) due to nodes' mobility, connection intermittency, limited nodes' energy and the dynamic changing quality of the wireless channel. However, only one or several of the above factors are considered in most current routing approaches. In this paper, we propose an efficient energy-aware probabilistic routing approach for MONs. Firstly, we explore and exploit the regularity of nodes' mobility and the encounter probability among nodes to decide the time when to forward messages to other nodes. Secondly, by controlling the energy fairness among nodes, we try to prolong the network lifetime. Thirdly, by fully taking the dynamic changing quality of the wireless channel into consideration, we effectively reduce the retransmission number of messages. Additionally, we adopt a forwarding authority transfer policy for each message, which can effectively control the number of replicas for each message. Simulation results show that the proposed approach outperforms the existing routing algorithms in terms of the delivery ratio and the overhead ratio.\",\n \"Title: Leveraging Neighborhood Summaries for Efficient Queries on Existing Relational RDF Systems\\nYear: 2017\\n\\nAbstract: Using structural informations to summarize graph-structured RDF data is helpful in tackling query performance issues. However, leveraging structural indexes needs to revise or even redesign the internal of RDF systems. Given an RDF dataset that have already been bulk loaded into a relational RDF system, we aim at improving the query performance on such systems. We do so by summarizing neighborhood structures and encoding them into triples which can be managed along side the exist instance data. At query time, we optimally select the effective structural patterns, and adding these patterns to the existing queries to gain an improved query performance. Empirical evaluations shown the effectiveness of our method.\",\n \"Title: Querying Rdf Graphs Over Partitioned Indexes\\nYear: 2017\\n\\nAbstract: We consider the problem of improving the query response time over a large-scale RDF collection. Existing methods need to maintain either all intermediate results or all graph structured data, which result in efficiency problems for complex queries. Our main idea is to introduce a two-level processing. The first level is performed as subgraph matching over a partition-based summary graph, which output coarse-grained matched partitions in a stream fashion. Then the fine-grained joins are processed on the matched partitions and generates the final results. Our method is efficient in that it avoid processing on large SPO permutation index at query time. An extensive experimental study using benchmark and real dataset shows that the query performance of our approach outperforms existing systems by orders of magnitudes.\",\n \"Title: User social activity-based routing for cognitive radio networks.\\nYear: 2018\\n\\nAbstract: The social activities of Primary Users (PUs) and Secondary Users (SUs) affect actual accessible whitespace in Cognitive Radio Networks (CRNs). However, the impacts of primary activities on available whitespace have been extensively investigated due to the dominating priority of PUs, while the impacts of secondary activities on actual accessible whitespace have been ignored. Therefore, we propose to incorporate the primary and secondary activities in the analysis and decision of the accessible whitespace, namely, both the dominance of PUs over SUs and the competitions among SUs are simultaneously taken into account. Specifically, we first approximate primary activity probability based on the real datasets of mobile phone usage records, then the spectrum opportunity between a pair of communication SUs is deduced based on primary activities. Next, we infer the access probability limit of SUs successfully accessing the whitespace according to the primary activity probability, and depict the secondary activity probability from the views of social activity patterns and social networks respectively. Furthermore, the actual accessible probability of whitespace is given by introducing the competitions among SUs. Finally, a greedy routing algorithm, considering the accessible whitespace and the distance to the destination, is proposed to verify our idea. The experiment results based on the real datasets demonstrate the correctness of our analysis and the advantages of the proposed algorithm.\",\n \"Title: A CTMDP-Based Exact Method for RCPSP with Uncertain Activity Durations and Rework.\\nYear: 2017\\n\\nAbstract: Many practical projects incorporate random rework, which leads to a stochastic project network structure. Until now, however, there have been only few works in the literature that have looked into this particular aspect of project planning and scheduling. In this paper, we consider a resource-constrained project scheduling problem (RCPSP) with exponentially distributed activity durations and two types of random rework. A mathematical model is proposed based on a continuous-time Markov decision process (CTMDP) with the objective to minimize the expected project makespan, which is further converted into an equivalent DTMDP with removing the self-transitions. In order to cope with the curse of dimensionality that comes into play upon solving large-scale instances, we examine a decomposition and parallel method that limits the memory usage. In addition, we also analyze the effect of random rework on the expected project makespan and the optimal rework strategy. Finally, a computational experiment is set up to validate the effectiveness of the proposed model and procedures.\",\n \"Title: A hybrid short-term traffic flow forecasting model based on time series multifractal characteristics.\\nYear: 2018\\n\\nAbstract: Short-term traffic flow forecasting is a key problem in the area of intelligent transportation systems (ITS). Timely and accurate traffic state prediction is also the prerequisite of realizing proactive traffic control and dynamic traffic assignment effectively. In this paper, a new hybrid model for short-term traffic flow forecasting, which is built based on multifractal characteristics of traffic flow time series, is proposed. The hybrid model decomposes traffic flow series into four different components, namely a periodic part, a trend part, a stationary part and a volatility part, to unearth the traffic features hidden behind the data. Four parts are treated and modeled separately by using different methods, such as spectral analysis, time series and statistical volatility analysis, to further explore the underlying traffic patterns and improve forecasting accuracy. Performance of the proposed hybrid model is investigated with traffic flow data from freeway I-694 EB in the Twin Cities. The experimental results indicate that the proposed model outperforms in capturing nonlinear volatility and improving forecasting accuracy than traditional forecasting methods, especially for the multi-step ahead forecasting. Compared with the ARIMA-GARCH model, it gets an improvement of 8.23% in RMSE for one-step ahead forecasting and 10.69% for ten-step ahead forecasting. It is better than the hybrid model newly proposed in literature (Zhang et al. Transp Res Part C: Emerg Technol 43(1):65–78 2014) and gets an improvement of 1.27% in forecasting accuracy.\",\n \"Title: Velocity Control Based on Active Disturbance Rejection for Air-Breathing Supersonic Vehicles.\\nYear: 2018\\n\\nAbstract: This paper investigates a velocity tracking control approach for air-breathing supersonic vehicles with uncertainties and external disturbances. Considering angle of attack is difficult to be precisely measured in practice, extended state observer technique is introduced into the state reconstruction design. In order to avoid possible oscillations in the design of the traditional extended state observer (TESO), a modified extended state observer (MESO) is developed, where a new smooth function is proposed to replace nonsmooth function of TESO. On the basis of it, an active disturbance rejection controller (ADRC) is designed for velocity control systems. Simultaneously, the closed-loop stability is rigorously proved by using Lyapunov theory. Finally, numeric simulations are conducted to validate the effectiveness of the proposed method.\",\n \"Title: ROSIE: Runtime Optimization of SPARQL Queries over RDF Using Incremental Evaluation.\\nYear: 2018\\n\\nAbstract: RDF (Resource Description Framework) is a proposed standard for knowledge representation, with relational databases wildly adopted in RDF data management. For efficient evaluation of SPARQL queries over RDF data, the legacy query optimizer needs reconsiderations. One vital problem is how to tackle the suboptimal query plan caused by error-prone cardinality estimation. For RDF data, determine an optimal execution order before the query actually evaluated is costly, or even infeasible. In this paper, we propose ROSIE, a Runtime Optimization framework that iteratively re-optimize SPARQL query plan according to the actual cardinality derived from Incremental partial query Evaluation. By introducing an approach for heuristic-based plan generation, as well as a mechanism to detect cardinality estimation error at runtime, ROSIE relieves the problem of biased cardinality propagation in an efficient way. Extensive experiments on real and benchmark data have shown that, compared to the state-of-the-arts, ROSIE consistently outperformed on complex queries by orders of magnitude.\",\n \"Title: Verifiable Public Key Encryption With Keyword Search Based on Homomorphic Encryption in Multi-User Setting.\\nYear: 2018\\n\\nAbstract: Data security and privacy concerns are important issues in cloud storage. In this paper, we propose a verifiable public key encryption with keyword search based on homomorphic encryption in multi-user setting. By employing van Dijk, Gentry, Halevi, and Vaikuntanathan homomorphic encryption, the proposed scheme enables the cloud server to generate an inverted encryption index structure without using a query trapdoor, which significantly improves the efficiency of search. On the other hand, the proposed scheme presents a new authenticated data structure based on the inverted encryption index structure, and shows how to apply it to verify the correctness and completeness of search results. Moreover, the proposed scheme allows multiple users to perform encrypted keyword search over encrypted data. Finally the proposed scheme is proved secure based on the approximate-GCD problem. The experiment results demonstrate the proposed scheme has less computation overhead than the existing schemes.\",\n \"Title: Reaction-diffusion equation based image restoration.\\nYear: 2018\\n\\nAbstract: We present a novel restoration algorithm based on the reaction–diffusion equation theory, denominated RDER, for restoring images which are corrupted by various blur PSFs and different types of noise (including different levels of impulse noise, Gaussian noise and mixed noise). The focus of this work is to propose an image restoration method based on the reaction diffusion equation and to further extend the traditional diffusion equation. Firstly, the RDER model is constructed by using the restoration ability of the diffusion equation, and the image detail preservation ability of the reaction equation; secondly, based on the difference scheme theory, a discrete RDER model is proposed for image restoration and a RDER algorithm for restoring the image is designed; thirdly, we mathematically analyze the RDER model from the existence, stability and uniqueness of solutions of the RDER model; finally, the proposed RDER algorithm is compared with the current famous state-of-the-art restoration algorithms in image restoring and image details preserving. Theoretical analysis and extensive experimental results show that the RDER is an effective image restoration algorithm for image denoising, image deblurring and image details preserving; in particular, the RDER provides a better performance in terms of the impulse noise and mixed noise.\",\n \"Title: A multivariate short-term traffic flow forecasting method based on wavelet analysis and seasonal time series.\\nYear: 2018\\n\\nAbstract: Short-term traffic flow forecasting is a key step to achieve the performance of intelligent transportation system (ITS). Timely and accurate traffic information prediction is also the prerequisite of realizing proactive traffic control and dynamic traffic assignment effectively. Based on the fact that univariate forecasting methods have limited forecasting abilities when the data is missing or erroneous and that single models make no full use of information underline data, a new hybrid method with multivariate for short-term traffic flow forecasting is proposed. This method combines statistical analysis method with computational intelligence techniques to mine the characteristic of traffic flow as well as forecast short-term traffic state. First, the wavelet de-noising is employed to remove the noise information. Then, time series analysis is used to analyze time-varying and periodic characteristic of traffic flow. Furthermore, the seasonal auto-regressive moving average with external input (SARIMAX) is established to fit traffic flow with occupancy as exogenous variables. Finally, wavelet forecast is adopted to forecast the values of occupancy which are used as exogenous input, and a WSARIMAX is constructed to forecast traffic flow. Using the relationship of flow and occupancy at the same road section and taking traffic flow and occupancy data from freeway I-694 EB in the Twin Cities as endogenous variables and exogenous variables respectively, this paper studies the forecasting performance of the proposed method. The study results are encouraging. Compared with SARIMA newly proposed in literature, WSARIMA and SARIMAX improved method with wavelet analysis and multivariate modeling method, the proposed method gets improvements of 12.95%, 12.62% and 10.41% in forecasting accuracy of one-step ahead respectively. For ten-steps ahead forecasting, it gets improvements of 18.87%, 17.05% and 2.57% in forecasting accuracy respectively.\",\n \"Title: A Second Order in Time, Decoupled, Unconditionally Stable Numerical Scheme for the Cahn-Hilliard-Darcy System.\\nYear: 2018\\n\\nAbstract: We propose a novel second order in time, fully decoupled and unconditionally stable numerical scheme for solving the Cahn–Hilliard–Darcy system which models two-phase flow in porous medium or in a Hele–Shaw cell. The scheme is based on the ideas of second order convex-splitting for the Cahn–Hilliard equation and pressure-correction for the Darcy equation. The computation of order parameter, pressure and velocity is completely decoupled in our scheme. We show that the scheme is uniquely solvable, unconditionally energy stable and mass-conservative. Ample numerical results are presented to gauge the efficiency and robustness of our scheme.\",\n \"Title: Proteus: network-aware web browsing on heterogeneous mobile systems\\nYear: 2018\\n\\nAbstract: ABSTRACTWe present Proteus, a novel network-aware approach for optimizing web browsing on heterogeneous multi-core mobile systems. It employs machine learning techniques to predict which of the heterogeneous cores to use to render a given webpage and the operating frequencies of the processors. It achieves this by first learning offline a set of predictive models for a range of typical networking environments. A learnt model is then chosen at runtime to predict the optimal processor configuration, based on the web content, the network status and the optimization goal. We evaluate Proteus by implementing it into the open-source Chromium browser and testing it on two representative ARM big.LITTLE mobile multi-core platforms. We apply Proteus to the top 1,000 popular websites across seven typical network environments. Proteus achieves over 80% of best available performance. It obtains, on average, over 17% (up to 63%), 31% (up to 88%), and 30% (up to 91%) improvement respectively for load time, energy consumption and the energy delay product, when compared to two state-of-the-art approaches.\",\n \"Title: Assessment of cerebral blood flow in neonates and infants: A phase-contrast MRI study.\\nYear: 2019\\n\\nAbstract: Abnormal cerebral blood flow (CBF) is implicated in several neonatal and infant diseases. However, measurement of CBF in this population remains difficult and has not been used in routine clinical MRI. Arterial spin labeling (ASL) methods suffer from both low SNR and poor quantification when applied to very young children. Furthermore, rapid change in brain physiology in this age range makes it difficult to choose sequence parameters such as labeling pulse flip angle and post labeling delay. Phase-contrast (PC) MRI is another approach to measure flow. It provides fast and reliable global CBF assessment, and has great promises in pediatric applications. In this study, we aimed to apply PC-MRI technique for CBF quantification in neonates and infants up to 18 months of age. We first compared several implementations of time-of-flight (TOF) MR angiogram for the visualization of brain's feeding arteries, which provides anatomical information for the positioning of PC-MRI scans. We then measured flow velocity and CBF of the internal carotid artery (ICA) and vertebral artery (VA) in 21 subjects (age 34–114 gestational weeks, 3 females, 18 males), using six encoding velocities (Venc) in each vessel. In ICA, peak arterial flow velocity was 10.2 cm/s at birth and increased to 56.0 cm/s at 18 months old. These values were 4.5–36.3 cm/s, respectively, for VA. CBF after accounting for brain volume revealed a significant (p < 0.001) age-related increase from 13.1 to 84.7 ml/100 g/min within the first 18 months after birth. Based on the peak flow velocity, we provided age-specific recommendations for Venc selection in PC-MRI when one only has time for one scan. The present study used a multi-Venc scheme to determine flow velocities in major feeding arteries of infant brain and may lay a foundation for accurate measurement of whole-brain CBF in this population.\",\n \"Title: Big data management challenges in health research-a literature review.\\nYear: 2019\\n\\nAbstract: Big data management for information centralization (i.e. making data of interest findable) and integration (i.e. making related data connectable) in health research is a defining challenge in biomedical informatics. While essential to create a foundation for knowledge discovery, optimized solutions to deliver high-quality and easy-to-use information resources are not thoroughly explored. In this review, we identify the gaps between current data management approaches and the need for new capacity to manage big data generated in advanced health research. Focusing on these unmet needs and well-recognized problems, we introduce state-of-the-art concepts, approaches and technologies for data management from computing academia and industry to explore improvement solutions. We explain the potential and significance of these advances for biomedical informatics. In addition, we discuss specific issues that have a great impact on technical solutions for developing the next generation of digital products (tools and data) to facilitate the raw-data-to-knowledge process in health research.\",\n \"Title: A novel energy-efficient probabilistic routing method for mobile opportunistic networks\\nYear: 2018\\n\\nAbstract: In mobile opportunistic networks (MONs), a large number of intelligent devices carried by moving people can conduct message transmission without the support of communication infrastructures. Routing is one of the concerning and challenging research hotspots in MONs because of nodes’ mobility, intermittent connectivity, limited nodes’ energy, and the dynamic changing quality of the wireless channel. However, only one or several of the above factors are considered in most current routing methods. Moreover, owing to the high mobility of nodes, it is particularly important to decide the time when to make the forwarding decision and which nodes can be selected as the relay nodes. Additionally, due to the dynamic changing quality of the wireless channel, the predetermined relay nodes for the next hop may not receive the message. In this paper, we propose a novel energy-efficient probabilistic routing method for MONs, in which energy and mobility of nodes and the quality of wireless channel are all taken into account. Firstly, we explore the regularity of nodes’ mobility and the encounter probability among nodes to decide the time when to forward messages to other nodes. Secondly, by maintaining the energy fairness among nodes, the network lifetime can be prolonged. Thirdly, by fully taking the dynamic changing quality of the wireless channel into consideration, the retransmission number of messages can be effectively reduced. Additionally, we adopt a forwarding authority transfer policy for each message, which can effectively control the number of replicas for each message. The extensive simulation results show that the proposed method outperforms the existing routing algorithms in terms of the delivery ratio and the overhead ratio.\",\n \"Title: Efficient and secure auditing scheme for outsourced big data with dynamicity in cloud.\\nYear: 2018\\n\\nAbstract: Big data offers significant benefits; however, security and privacy problems must be considered, especially with regard to outsourced big data. Auditing outsourced big data is an important factor in security and privacy. However, most of the existing auditing techniques are not suitable for outsourced big data due to their high computational and communication costs at the auditor and the data owner (DO) side. In this paper, we propose an efficient auditing scheme for outsourced big data based on algebraic signatures and an XOR-homomorphic function, that can achieve numerous advantages, such as fewer challenges and proofs, non-block verification, data privacy preservation, and lower computational and communication costs. The proposed scheme enables a trusted third-party auditor, on behalf of DOs, to audit the outsourced data in a cloud. Thus, reducing the computational burden on the DOs. Subsequently, we construct a new data structure called a Record Table (RTable) and extend the basic auditing scheme to support the data dynamic operations. As our extended scheme does not use public key encryption, the entire process of updating the data incurs only a small computational and communication overhead with regard to the auditor, the DOs, and the cloud server. Finally, the proposed basic scheme is proved secure under the security model against various attacks. Analysis of the performance shows that both our basic scheme and extended scheme are highly efficient.\",\n \"Title: Power Allocation Optimization in MC-NOMA Systems for Maximizing Weighted Sum-Rate.\\nYear: 2018\\n\\nAbstract: In this paper, we investigate a power allocation scheme in downlink multi-carrier non-orthogonal multiple access (MC-NOMA) systems for maximizing weighted sum-rate. Taking user-priority into account, we add the weighting factors into the formulated optimization problem. Firstly, we give sufficient and necessary concavity conditions that should be satisfied by the proposed weighted sum-rate maximization problem. Then, for more generally non-concave case, we use a first order approximation to convert the optimization problem and provide an iterative power allocation algorithm to find the globally optimal solution. Simulation results show that our proposed algorithm is superior to orthogonal frequency division multiple access (OFDMA) scheme and average power allocation scheme.\",\n \"Title: An efficient probabilistic routing scheme based on game theory in opportunistic networks.\\nYear: 2019\\n\\nAbstract: Routing is one of the most challenging problems in opportunistic networks (OppNets) because of the intermittence of the network connection. To address the issue, many routing schemes have been proposed, however, most of them assume that nodes are willing to forward messages for others. In fact, due to limited resources and poor social relations, nodes in OppNets may be selfish and not reluctant to participate in message forwarding. To tackle this issue, in this paper, we propose a Probabilistic Routing scheme based on Game Theory (PRGT) to stimulate cooperation among selfish nodes. Firstly, we introduce virtual money to buy the message for gaining more profits. Then, according to the historical meeting records among different nodes, we establish a Markov-based probability prediction model, in which the message carrier selects a node with higher probability of encountering the destination node as the relay node. Finally, a game theory approach is employed to simulate trading price for message forwarding. The simulation results demonstrate that our proposed routing scheme can effectively improve the delivery rate of messages and reduce network latency.\",\n \"Title: Radio Resource Allocation Scheme for Drone-Assisted AR Applications\\nYear: 2018\\n\\nAbstract: Mobile edge computing facilitates the implementation of computationally intensive applications on mobile devices, such as Mobile Augmented Reality (MAR). The MAR application usually includes three modules, namely, data collection in the uplink, edge computing and data transmission in the downlink, and the cooperation between the modules will help improve the energy consumption performance of the AR system. We propose an integrated MAR transmission design with companion drones and a high energy efficiency resource allocation scheme. Through a successive convex approximation (SCA) algorithm, we convert non-convex problems into convex ones for optimal solution. Compared with traditional independent offloading by users, joint relay transmission and shared uplink data offloading schemes can produce significant gains in energy efficiency.\",\n \"Title: Eavesdropping and Jamming Selection Policy for Suspicious UAVs Based on Low Power Consumption over Fading Channels.\\nYear: 2019\\n\\nAbstract: Traditional wireless security focuses on preventing unmanned aerial vehicle (UAV) communications from suspicious eavesdropping and/or jamming attacks. However, there is a growing need for governments to keep malicious UAV communications under legitimate surveillance. This paper first investigates a new surveillance paradigm for monitoring suspicious UAV communications via jamming suspicious UAVs. Due to the power consumption limitation, the choice of eavesdropping and jamming will reflect the performance of the UAVs communication. Therefore, the paper analyses the UAV's eavesdropping and jamming models in different cases, and then proposes the model to optimize the data package in the constraints of lower power consumption, which can be solved by the proposed selection policy. The simulation results validate our proposed selection policy in terms of power consumption and eavesdropped packets. In different fading models, power consumption increases with time, regardless of distances, and our proposed policy performs better in Weibull fading channels in terms of eavesdropped packets.\",\n \"Title: Improvement of Reflection Detection Success Rate of GNSS RO Measurements Using Artificial Neural Network.\\nYear: 2018\\n\\nAbstract: Global Navigation Satellite System (GNSS) radio occultation (RO) has been widely used in the prediction of weather, climate, and space weather, particularly in the area of tropospheric analyses. However, one of the issues with GNSS RO measurements is that they are interfered with by the signals reflected from the earth's surface. Many RO events are subject to such interfered GNSS measurements, whi...\",\n \"Title: A location-sensitive over-the-counter medicines recommender based on tensor decomposition\\nYear: 2019\\n\\nAbstract: The last few decades have witnessed a steady increase in medicine prescriptions for the treatment of biometric markers rather than obvious physiological symptoms; especially, the over-the-counter (OTC) medicine experiences rated by patients have huge potential to assist people to make more appropriate decisions. The most existing researches focus on the rating prediction and recommendations in E-commerce field rather than healthcare or medical treatments. In addition, the spatial and temporal factors were not considered in their recommendation mechanisms. Toward this end, this paper propose an efficient OTC medicines recommendation strategy based on tensor decomposition. Considering the impact of regional differentiation, a third-order tensor including medicine, location, and rating is constructed. To inference the usage of a new OTC medicine in a certain location, high-order singular value decomposition is applied to the above tensor for obtaining the intelligent recommendation. In order to evaluate the effectiveness of the proposed approach, we compared the conventional collaborative filtering approach and tensor-based approach in terms of precision and recall. The experimental results demonstrate that our proposed approach is significant better than collaborative filtering approach.\",\n \"Title: Authentication scheme based on smart card in multi-server environment\\nYear: 2020\\n\\nAbstract: For authentication schemes based on smart card in multi-server environment, there is a common problem—the parameters stored in a user’s smart card linearly increase with the number of the registered servers without involving registration center in helping with authentication process. Therefore, in order to save storage cost and raise efficiency, an authentication scheme based on smart card is proposed in multi-server environment. In the proposed scheme, a user only needs one time registration, and keeps a password to realize the authentication with different servers without involving the registration center in helping with authentication process. The server is unnecessary to store any users information to achieve authentication between the users and the server. Moreover, the security of the proposed scheme is proved by Burrows–Abadi–Needham logic. The security analysis and the performance analysis show the proposed scheme is secured against various well known attacks, and has lower communication cost, computation cost and storage cost compared with several related schemes.\",\n \"Title: Heuristic Localization Algorithm with a Novel Error Control Mechanism for Wireless Sensor Networks with Few Anchor Nodes.\\nYear: 2018\\n\\nAbstract: A novel iterative localization algorithm with high accuracy and low anchor node dependency for large-scale wireless sensor networks is proposed in this paper. At each iteration, blind nodes are located using a weighted linear least squares-based algorithm. To prevent errors in the blind nodes from propagating and accumulating throughout the network, an anchor geometric feature-based error control mechanism is used to select the nodes that participate in the localization and to estimate the localization confidence. The simulation results show that the algorithm can be used when only a few anchor nodes are involved. This algorithm is more advanced than traditional methods, which often require a large number of well-placed anchor nodes to operate appropriately. By optimizing the decision parameter v of the algorithm, the average localization error of the algorithm is approximately 0.43 meters. When the ratio of anchor nodes (the ratio of the number of anchor nodes to the number of sensor nodes in the network) is 1.25% (i.e., 5 anchor nodes for 400 sensor nodes), the received signal strength indicator (RSSI) variance is 8 dBm, and the radio range is 50 meters. A comparison of the proposed algorithm with global localization methods, including multidimensional scaling (MDS), semidefinite programming (SDP), and shortest-path access (SPA), shows that the proposed algorithm achieves higher location accuracy and stability when the number of anchor nodes is varied. The efficiency of the proposed localization algorithm is evaluated in a real sensor network, and the accuracy is high and robust to radio channel variance.\",\n \"Title: The Prediction Model of Saccade Target Based on LSTM-CRF for Chinese Reading.\\nYear: 2018\\n\\nAbstract: Through introducing the psychology model of reading cognitive, this paper uses the LSTM neural network and the CRF model respectively to simulate the language cognition process and the eye-movement control process in reading, in order to overcome the defect that the traditional CRF prediction model only considers the context information of the label sequence but can not take into account the context information of the text sequence. First, the psychological process of reading cognition is introduced and the prediction model of saccade target based on LSTM-CRF for Chinese reading is proposed. Then, the experimental data, experimental environment, feature templates and parameter settings needed for model training are introduced. Finally, the conclusion is drawn through experimental comparison: (1) The F1 score of prediction model in saccade labeling based on LSTM-CRF is superior to the traditional CRF prediction model; (2) The predictability of the language itself is an important feature of the saccade target prediction model; (3) The best saccade length for Chinese readers is about 2.5 Chinese characters.\",\n \"Title: -Hyers-Ulam-Rassias Stability of Semilinear Nonautonomous Impulsive System.\\nYear: 2019\\n\\nAbstract: In this paper, we study a system governed by impulsive semilinear nonautonomous differential equations. We present the beta-Ulam stability, beta-Hyers-Ulam stability and beta-Hyers-Ulam-Rassias stability for the said system on a compact interval and then extended it to an unbounded interval. We use Gronwall type inequality and evolution family as a basic tool for our results. We present an example to demonstrate the application of the main result.\",\n \"Title: Generalized Spatial Modulation based on Array-Blocks for Millimeter Wave High Speed Railway Communication Systems\\nYear: 2018\\n\\nAbstract: Generalized Spatial Modulation (GSM) technology is a new multiple-input multiple-output (MIMO) technique that can improve spectral efficiency in wireless communication systems. In this paper, a generalized spatial modulation based on array-blocks (AB-GSM) scheme is proposed for the mmWave high speed railway (HSR) communication systems. In the proposed AB-GSM scheme, GSM is adopted at transmitter and more than one array-blocks are simultaneously activated at the base station (BS) to transmit data. Modulated symbols are transmitted by using the radio frequency (RF) beamforming technology. The information bit rate and bit error rate (BER) performance of the AB-GSM system under mmWave channel model are investigated. Theoretical analysis and simulation results show that the proposed AB-GSM scheme has a considerable improvement in the data transmission rate and spectral efficiency compared with the traditional GSM.\",\n \"Title: Energy-Efficient Power Allocation with Buffer Constraint for High-Speed Railway\\nYear: 2018\\n\\nAbstract: To satisfy the increasing demands for high data-rate service of high-speed railway (HSR) users on the train, the most promising approach is to utilize the two-hop architecture. With this architecture, large amount of data will be transferred to the access point (AP) at which some data may need to be cached when the train approaches the cell edge. In this paper, an energy-efficiency buffer (EEB) power allocation scheme is proposed, which is able to achieve a high energy efficiency under the requirement of buffer size in HSR scenarios. Firstly, the energy-efficiency optimization problem is formulated as a fractional form. Secondly, this non-convex problem is resolved by transforming it into an equivalent one. Then an iterative power allocation algorithm is proposed and the optimal solution is obtained based on it. Finally, we analyze the effect of cache point on energy efficiency (EE) performance of the proposed EEB power allocation scheme. Furthermore, the relationship between the buffer size and EE performance of HSR communication system is presented. Simulation results suggest that the proposed EEB power allocation scheme can achieve the optimal energy-efficient performance.\",\n \"Title: A Second Order BDF Numerical Scheme with Variable Steps for the Cahn-Hilliard Equation.\\nYear: 2019\\n\\nAbstract: We present and analyze a second order in time variable step BDF2 numerical scheme for the Cahn-Hilliard equation. The construction relies on a second order backward difference, convex-splitting technique and viscous regularizing at the discrete level. We show that the scheme is unconditionally stable and uniquely solvable. In addition, under mild restriction on the ratio of adjacent time-steps, an optimal second order in time convergence rate is established. The proof involves a novel generalized discrete Gronwall-type inequality. As far as we know, this is the first rigorous proof of second order convergence for a variable step BDF2 scheme, even in the linear case, without severe restriction on the ratio of adjacent time-steps. Results of our numerical experiments corroborate our theoretical analysis.\",\n \"Title: Efficient <tex>$K$</tex>-concern Matching in a Large Graph\\nYear: 2018\\n\\nAbstract: Exact subgraph matching is wildly used for relation exploration in linked data. Existing literatures of matching algorithm focus on exhaustive enumeration of all matches, which are both time and space consuming and even not viable for a large graph. For real world applications such as social search, it is common that not all entities in a query graph are concerned by the users. It is not trivial to find distinct groups of concerned vertices from the exhaustive enumeration of all matches. In this paper, we define the problem of K-concern matching which returns distinct groups of K concerned vertices in all matches. In order to efficiently find K -concern matches in a large graph, we devise a new strategy for the general backtracking algorithm. To minimize the total search space, we propose methods for search order optimization and candidate set pruning. Experiments on real and synthetic datasets show that the query performance of our method exceeds all existing matching algorithms for K-concern matching.\",\n \"Title: Structure regularized sparse coding for data representation.\\nYear: 2019\\n\\nAbstract: Sparse coding (SC) exhibits impressive performance in many practical applications. However, in the unsupervised scenario, most of the conventional SC methods fail to fully take advantage of the structure of the data. Actually, the structure of the data, especially the global structure that is an implicit prior knowledge, is vital for data analysis. In this paper, we propose a novel method called structure regularized sparse coding (SRSC) for the sparse representation of the data in the unsupervised scenario. In contrast with the other SC methods, a distinct feature of SRSC is that it takes into consideration both the local and global structure of the data and fully exploits the latent category information in the data. By using the local affinity matrix that captures the local structure, we first build a global affinity matrix to encode the global structure of the data. The global affinity matrix fully carries the latent category information that is beneficial to obtain the discriminating representation of the data, Then, we define the optimization model of SRSC and develop a two-step iterative optimization algorithm based on the alternating direction method of multipliers (ADMM) to solve it. The experimental results validate that the proposed method is effective and can achieve better performance over its counterparts.\",\n \"Title: Design And Experimental Verification On Characteristics Of Valve-Less Piezoelectric Pump Effected By Valve Hole Spacing\\nYear: 2019\\n\\nAbstract: Valve-less piezoelectric pumps possess the advantages of simple structure and absence of electromagnetic interference, which has accordingly drawn widespread attention. In this paper, in order to improve the performance of valve-less piezoelectric pumps, various kinds of the prototypes had been designed and fabricated to discover the relationship between the performance and the structural parameters of valve hole spacing. The prototype is comprised of a piezoelectric actuator and a pump chamber through a conical tube that connects the pump chamber with the buffer chamber. First, the flow characteristics of the valve-less pump were performed by using COMSOL Multiphysics. According to the simulation result, the decline of flow velocity around the valve holes on the side far from the center of the pump chamber may be the reasons for the performance degradation. Second, the effect of valve hole spacing on the prototype was investigated with respect to several parameters, such as the chamber height and cone angle. The experimental results indicated that the valve-less piezoelectric pump output flowrate can be improved by reducing spacing valve hole spacing. A maximum flowrate of 8.43mL/min was achieved at valve hole spacing of 3 mm, which is 13.6% and 47.1% higher than that at 15 mm and 25 mm, respectively. We finally verify the feasibility of improving the capacity of valve-less piezoelectric pumps by reducing valve hole spacing.\",\n \"Title: A New Type of Eye Movement Model Based on Recurrent Neural Networks for Simulating the Gaze Behavior of Human Reading.\\nYear: 2019\\n\\nAbstract: Traditional eye movement models are based on psychological assumptions and empirical data that are not able to simulate eye movement on previously unseen text data. To address this problem, a new type of eye movement model is presented and tested in this paper. In contrast to conventional psychology-based eye movement models, ours is based on a recurrent neural network (RNN) to generate a gaze point prediction sequence, by using the combination of convolutional neural networks (CNN), bidirectional long short-term memory networks (LSTM), and conditional random fields (CRF). The model uses the eye movement data of a reader reading some texts as training data to predict the eye movements of the same reader reading a previously unseen text. A theoretical analysis of the model is presented to show its excellent convergence performance. Experimental results are then presented to demonstrate that the proposed model can achieve similar prediction accuracy while requiring fewer features than current machine learning models.\",\n \"Title: Petri net-based methods for analyzing structural security in e-commerce business processes\\nYear: 2020\\n\\nAbstract: The rapid development of e-commerce worldwide, means more e-commerce business processes adopting the structure of multiple participants; these include shopper clients, merchant and third-party payment platforms (TPPs), banks, and so on. It is a distributed and complex system, where communications among these participants rely on the web services and Application Programming Interfaces (APIs) such as Cashier-as-a-Service or CaaS. This introduces new security challenges due to complex interactions among multiple participants, and any design flaws in procedure structures may result in serious security issues. We study the structural security issues based on Petri nets, and a framework for analyzing structural security in e-commerce business process is proposed. Petri net-based modeling and analysis methods are also provided. Given the specifications of e-commerce business processes, the proposed methods can help designers analyze structural security issues of an e-commerce business process.\",\n \"Title: Stability Of ?-Schemes For Partial Differential Equations With Piecewise Constant Arguments Of Alternately Retarded And Advanced Type\\nYear: 2019\\n\\nAbstract: This paper deals with the analytical and numerical stability of a partial differential equation with piecewise constant arguments of alternately retarded and advanced type. Firstly, the theory of separation of variables in matrix form and the Fourier method are implemented to achieve the sufficient conditions under which the analytic solution is asymptotically stable. Secondly, the discrete equation is obtained by applying the ?-schemes to the original continuous equation, the sufficient conditions for the asymptotic stability of numerical solution are also shown when the mesh ratio satisfying certain conditions. Finally, some numerical experiments for verifying the theoretical results are provided.\",\n \"Title: A multimedia image edge extraction algorithm based on flexible representation of quantum\\nYear: 2019\\n\\nAbstract: To solve the real-time problem of edge extraction algorithm and improve image edge continuity, an edge extraction algorithm based on quantum flexible representation (flexible representation of Quantum, RFQ) is proposed. First, the image is represented by quantum flexibility, the superposition state of the quantum sequence is used to store all the pixels of the image, and the FRQ image is obtained by the quantum parallel computation which efficiency is greatly improved, secondly, by the translation transformation of the X and Y directions of the FRQ image, the relative quanta of the neighboring pixels of the whole image is obtained. According to the quantum bit to define the quantum black boxUΩ, combining the Sobel operator to compute the Sobel gradient of pixels in order to judge different categories of pixels and extract the edges of the image. The experimental results show that the proposed method has better edge continuity and richer detail edge than the current edge extraction algorithm.\",\n \"Title: Distributed Finite-Time secondary control for DC Microgrids with Virtual Impedance Arrangement\\nYear: 2019\\n\\nAbstract: In direct current (DC) microgrids, the accurate current sharing could be achieved by regulating the virtual impedance (droop coefficient) and the output voltage average value of each distributed generator (DG) could be restored by regulating the voltage reference value with a secondary controller. However, there is a coupling relationship between the current sharing and the voltage restoration process. In this paper, a distributed finite-time secondary control strategy is proposed aiming at overcoming the coupling effect. The proposed controller consists of four control loops, which are the current sharing controller (CSC), the virtual impedance average value restoration controller (AIRC), the reference voltage consensus controller (RVCC), and the voltage average value restoration controller (AVRC). With the proposed controller, the coupling effect is eliminated and the virtual impedance of each DG is only determined by the system load distribution. Besides, a simplified control strategy is also proposed which only contains the CSC and AIRC, and the reference voltage value can be calculated using the local information. The stability of the proposed controller is analyzed using the Lyapunov method. At last, the proposed controller is simulated in MATLAB/Simulink to verify its effectiveness.\",\n \"Title: ACNN-FM: A novel recommender with attention-based convolutional neural network and factorization machines\\nYear: 2019\\n\\nAbstract: With the rapid development of the Internet, the data generated from application platforms such as online shopping, e-education, and digital entertainment has exhibited dramatical growth, which has caused serious information overload to Internet users. The traditional recommendation approaches are crucial for Internet users to extract valuable information from various information. However, there exist some problems such as sparse data, cold start, and over-reliance on manual extracted feature and so on. To address the above problems, this paper proposes a novel recommender with Attention-based Convolutional Neural Network and Factorization Machines (ACNN-FM), which achieves the recommendation with comments. Firstly, from the perspective of local to overall, this paper proposes a word-level attention mechanism and a phrase-level attention mechanism to increase the ability to remember the importance and the order of historical vocabulary (phrase) in the process of text processing of convolutional neural networks. Secondly, it constructs a model to automatically extract hidden features of users and items from comments in the form of natural language. Finally, we utilize factorization machines to analyze the association between the hidden features of users and items, and implement the recommendation based on the association. Extensive experiments are conducted for demonstrating that ACNN-FM method outperforms state-of-the-art NARR method, and ACNN-FM has the highest data utilization among NARR, DeepCoNN, BCF and NMF methods, thus the recommendation performance is significantly improved in large-scale data environment.\",\n \"Title: Efficient Coupling Diffusion of Positive and Negative Information in Online Social Networks\\nYear: 2019\\n\\nAbstract: The increasing popularization of large-scale online social networks (OSNs) facilitates information sharing. Users are able to diffuse positive and negative information independently owing to the high openness of the OSNs. Due to the intervention of user’s emotions and social relationships, the positive and negative information diffusion exhibits a complicated dynamic coupling diffusion process, in which the negative information diffusion can cause social panic and confusion. However, prior works mainly focus on the diffusion of single type of information. To fill this gap, this paper aims to investigate the dynamic diffusion process of the positive and negative information and control the negative information diffusion timely. Specifically, we first establish a coupling diffusion model to characterize the dynamic diffusion process under the coexistence of positive and negative information, then derive the critical condition for the negative information diffusion and certify the stability of the diffusion model. Furthermore, we propose two collaborative control strategies to persuade and guide users to diffuse the positive information simultaneously. Then, the issue of minimizing the total system costs is transformed to an optimal control problem. Finally, we prove the existence and uniqueness of optimal control solutions and obtain the dynamic distribution of optimal control strategies over time to minimize system costs. The experimental results obtained from two real-world datasets verify the effectiveness of our model and the high efficiency of the collaborative control strategies.\",\n \"Title: Genetic contribution to the phenotypic correlation between trait impulsivity and resting-state functional connectivity of the amygdala and its subregions.\\nYear: 2019\\n\\nAbstract: Trait impulsivity, a predisposition to respond to stimuli without regard for the potentially negative consequences, contributes to many maladaptive behaviors. Studies have shown that both genetic factors and interregional functional interactions underlie trait impulsivity. However, whether common genes contribute to both trait impulsivity and its neural basis is still unknown. This study investigated the phenotypic correlations between trait impulsivity and the resting-state functional connectivity (rsFC) of the amygdala as well as its subregions and the genetic contribution to the phenotypic correlations. By recruiting a sample of 292 twins in late adolescence and young adulthood, we found that trait impulsivity was positively correlated with the rsFC between the left full amygdala and the right dorsolateral prefrontal cortex (DLPFC). Further analyses on the subregions of the amygdala showed that trait impulsivity was positively correlated with the rsFCs between the left basolateral (BL) amygdala and both the right DLPFC and the right inferior frontal gyrus and with the rsFCs between the right superficial (SF) amygdala and both the dorsal anterior cingulate cortex and right anterior insula. Bivariate genetic modelling analyses found genetic overlaps between trait impulsivity and the rsFC of the left full amygdala or the left BL amygdala with the right DLPFC. The proportions of phenotypic associations accounted for by overlapping genes were 82% and 60%, respectively. These results provide evidence for the genetic overlap between trait impulsivity and the intrinsic brain functional connectivity centered at the amygdala and especially at its BL subregion.\",\n \"Title: Optimal Resource Allocation Via Machine Learning In Coordinated Downlink Multi-Cell Ofdm Networks Under High Mobility\\nYear: 2021\\n\\nAbstract: For a multi-cell OFDM downlink network, a basic problem is to perform resource allocation to maximize the spectral efficiency (SE). Doppler shift, however, leads to a loss of subcarrier orthogonality, resulting in inter-carrier interference (ICI), especially in a high speed environment. In this paper, we solve the resource allocation problem by considering ICI caused by Doppler spread and imperfect channel state information (CSI) caused by estimation errors, quantization errors and feedback delay. However, the resultant resource allocation algorithm is so complicated that it may not be applicable to the wireless communications environment under high mobility since it may change rapidly and therefore needs real-time computation. As such we propose a deep neural network (DNN) approach to approximate the resource allocation algorithm, which greatly reduces the computation time while achieving very good prediction accuracy. Simulation results verify the influence of Doppler shift on the SE performance and the effectiveness of DNNs in terms of computing time.\",\n \"Title: GNSS-RS Tomography: Retrieval of Tropospheric Water Vapor Fields Using GNSS and RS Observations\\nYear: 2022\\n\\nAbstract: High spatiotemporal resolution atmospheric water vapor can be retrieved using the Global Navigation Satellite System (GNSS) tomography technique, in which the remained ill-posed problem of the tomography system resulting from the acquisition geometry is a vital issue to be addressed. Remote sensing (RS) water vapor data, with high-resolution and global coverage, show great potential for retrieval of slant water vapor (SWV) observations to improve the tomographic geometrical distribution. In this article, we develop a GNSS-RS (GNSS combining RS) tomography model to fully exploit the value of observation signals from GNSS and RS measurements. The two key factors of retrieving the RS SWV are performed by calibrating the original precipitable water vapor (PWV) images and adding the tropospheric horizontal gradients. The results reveal that when introducing the RS SWV observations into the tomography model, the acquisition geometry is significantly improved, with the average rate of voxels crossed by rays from 62% to 95% and the mean number of observation signals from 395 to 508 during the tomographic periods. Independent radiosonde data are used to validate the tomographic water vapor fields. The mean root-mean-square error (RMSE) and bias of the water vapor profiles derived from GNSS-RS solutions are decreased by 28% and 45% with respect to the GNSS-only results, respectively. Such improvements highlight that GNSS-RS troposphere tomography has significant potential to improve the reconstruction of the atmospheric water vapor fields.\",\n \"Title: Generalization-error-bound-based discriminative dictionary learning\\nYear: 2022\\n\\nAbstract: Support vector guided dictionary learning, as a discriminative dictionary learning method combining with support vector machine (SVM), embodies the margin maximization principle and achieves good generalization performances in many practical applications. However, this method ignores the key fact that the generalization performance of the SVM classifier depends not only on the margin between two classes of training samples, but also on the radius of the smallest sphere covering them. In the paper, we propose a novel method called generalization-error-bound-based discriminative dictionary learning (GEBDDL). The basic insight of GEBDDL is that the coding vectors, which are used to build the SVM classifier, are not fixed during the learning process. As a result, the radius of the smallest sphere changes with the learned coding vectors. The key feature of GEBDDL is that it explicitly incorporates the radius-margin-bound, which is directly related to the upper bound of the leave-one-out error of SVM, into its objective function to guide learning the dictionary and the coding vectors, and building the SVM classifier. In the paper, we first elaborate our motivation and propose the optimization model and then discuss how to solve it in detail. Further, we explore how to approximate the radius of the smallest sphere in our methodology. This can enhance the computational efficiency by bypassing the quadratic programming problem of computing the radius, while yielding a close performance to GEBDDL. Finally, the comprehensive experiments are conducted on several benchmark datasets, and the results demonstrate the superiority of the proposed methods over the other competing methods.\",\n \"Title: Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based On Minimization Of Exciting Force\\nYear: 2021\\n\\nAbstract: The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors' geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.\",\n \"Title: Plantar Pressure Detection System Based On Flexible Hydrogel Sensor Array And Wt-Rf\\nYear: 2021\\n\\nAbstract: This paper presents a hydrogel-based flexible sensor array to detect plantar pressure distribution and recognize the gait patterns to assist those who suffer from gait disorders to rehabilitate better. The traditional pressure detection array is composed of rigid metal sensors, which have poor biocompatibility and expensive manufacturing costs. To solve the above problems, we have designed and fabricated a novel flexible sensor array based on AAM/NaCl (Acrylamide/Sodium chloride) hydrogel and PI (Polyimide) membrane. The proposed array exhibits excellent structural flexibility (209 KPa) and high sensitivity (12.3 mV center dot N-1), which allows it to be in full contact with the sole of the foot to collect pressure signals accurately. The Wavelet Transform-Random Forest (WT-RF) algorithm is introduced to recognize the gaits based on the plantar pressure signals. Wavelet transform realizes the signal filtering and normalization, and random forest is responsible for the classification of the processed signals. The classification accuracy of the WT-RF algorithm reaches 91.9%, which ensures the precise recognition of gaits.\",\n \"Title: Dual Attention Network Based on Knowledge Graph for News Recommendation\\nYear: 2021\\n\\nAbstract: With the continuous development of Internet technology, there are more and more online news readers, and the amount of news is huge and growing explosively. In addition, the news language is highly concentrated and contains a large number of entities. Currently, the commonly used recommendation methods are difficult to make full use of knowledge information and discover the potential interests of users. To solve the above problems, we propose a Dual attention network based on knowledge graph for news recommendation (DAKRec), which takes news titles, the entities contained in them and the contexts as input, and uses knowledge graph to extract news features. In order to better characterize the diversity of users' interests, a dual attention network is constructed to obtain the weight of users' historical news through word-level attention mechanism and item-level attention mechanism (integrating news words, entities, and contexts). Finally, the multi-head attention module is used to connect historical news and candidate news, and the click-through rate is calculated through a fully connected multilayer perceptron after feature fusion. Through a large number of experiments, we prove that our model DAKRec is better than the advanced DKN model and the other comparison models (FM, DMF) in AUC and MSE, further improves the recommendation performance.\",\n \"Title: A Knowledge Diffusion Model in Autonomous Learning Under Multiple Networks for Personalized Educational Resource Allocation\\nYear: 2021\\n\\nAbstract: Learners’ autonomous learning is at the heart of modern education, and the convenient network brings new opportunities for it. We notice that learners mainly use the combination of online and offline learning methods to complete the entire autonomous learning process, but most of the existing models cannot effectively describe the complex process of knowledge diffusion under the multinetworks fram...\",\n \"Title: A lightweight and fault-tolerable data aggregation scheme for privacy-friendly smart grids environment\\nYear: 2021\\n\\nAbstract: The smart grid has attracted great attention as a new energy network. The power supplier collects the total consumption data through the smart meter. The data aggregation is a common operation in smart grid. However, the majority of existing data aggregation schemes are based on homomorphic encryption, suffering from heavy computation overhead. Recently, Gope et al. put forward a masking-based data aggregation scheme in smart grid, but there are some security problems by analyzing their scheme. If one of consumption data does not arrive at the aggregator on time, the power supplier will get incorrect aggregation results. To address these issues, we propose a lightweight and fault-tolerable data aggregation scheme. It can determine which smart meters fail to upload data on time with the idea of flag bit, and then power supplier can calculate the masking value of failed smart meter. So the proposed scheme can ensure the correctness of the final aggregation result even if a smart meter fails to upload data. In addition, the proposed scheme can achieve authentication and data collection only using one round of communication interaction while other schemes need more rounds. Security proof shows that the proposed scheme can achieve indistinguishable privacy. Experimental data confirms the efficiency of the proposed scheme.\",\n \"Title: Flocking of uncertain nonlinear multi-agent systems via distributed adaptive event-triggered control\\nYear: 2021\\n\\nAbstract: This paper investigates flocking problems with uncertain nonlinear multi-agent systems. Two distributed adaptive event-triggered control algorithms are proposed for leaderless and leader-follower flocking, separately. According to Lyapunov stability theory, under the proposed control protocols, we obtain some sufficient conditions to ensure stable flocking motion and maintain connectivity of network topology. And it is proven that there is a positive lower limit of the interval between any two trigger events, which indicates that the Zeno behavior will not occur. As a result, communication bandwidth resources are effectively saved on the premise of stable flocking. Lastly, numerical simulations are presented to verify the availability of the theoretical results.\",\n \"Title: Fairness-Aware Power Allocation In Downlink Mimo-Noma Systems\\nYear: 2021\\n\\nAbstract: Non-orthogonal multiple access (NOMA) has attracted great attention due to its potential of providing high spectral efficiency and massive connectivity. Combining it with multiple-input multiple-output (MIMO) technology can further improve the spectrum efficiency. In this paper, the power allocation problem in downlink multi-cluster MIMO-NOMA systems is investigated for maximizing the fairness utility function. First, a long-term fairness function is considered and the optimization problem is formulated as a weighted sum-rate maximization problem. The problem is transformed into a convex form by introducing two sets of auxiliary variables, and propose an iterative algorithm to update the weight factors and the auxiliary variables. Then, an instantaneous fairness is considered and the optimization problem is formulated as a minimum data-rate maximization problem. It is transfiormed into a one-dimensional optimization problem based on an iterative algorithm and a closed-form power allocation expression is deduced. Simulation results illustrate that the proposed two fairness power allocation schemes have better performance of edge-user rate than the comparable schemes.\",\n \"Title: Svm-Based Online Learning For Interference-Aware Multi-Cell Mmwave Vehicular Communications\\nYear: 2021\\n\\nAbstract: This paper proposes a data-driven method of mmWave beam selection in multi-cell systems to achieve a near-optimal fast beam allocation with low complexity. In particular, an online learning algorithm based on support vector machine (SVM) equipped with the radial basis function kernel, namely SVM-based online beam selection (SBOS) algorithm is proposed. The proposed algorithm starts with an adaptive beam selection process for certain traffic pattern that uses an SVM learning model to adaptively refine the beam selection strategy. Specifically, SVM-based model labels the feedback (the average information rate) from the cellular system, then learns from samples, and makes the scheme space smaller by maximising samples' minimum distances to all labelled samples in the sample space constrained by newly learned boundaries. Then, according to the aggregated data about the traffic patterns and the performance of corresponding beam selection strategy, SBOS algorithm exploits beam selection schemes recorded in the database or explores new schemes for unknown situations, respectively, and how to tune the hyperparameters for the SBOS algorithm is discussed. Furthermore, the extensive simulation results show that the proposed algorithm achieves a better performance versus upper confidence bound and Random methods.\",\n \"Title: Pricing for Using Operator Platforms with Sharing Edge Services\\nYear: 2021\\n\\nAbstract: This paper explores the influence of competition between sharing edge service platforms. In particular, each server node in the edge network is regarded as an edge service provider(ESP). Each mobile device that needs to get edge services is considered as a user. There are two operators in the network, each of them offering a platform that contains several ESPs. Both platforms compete for users by ...\",\n \"Title: A secure cross-domain authentication scheme with perfect forward security and complete anonymity in fog computing\\nYear: 2021\\n\\nAbstract: Nowadays, fog computing has become an emerging hot-topic for possessing the same advantages as cloud computing and the lower latency. Nevertheless, there are still many issues in fog computing that worth studying, the most importantly of which are key agreement and user authentication. In order to achieve secure communication among different entities, designing a secure key agreement and user authentication scheme becomes an urgent issue. Although many schemes have been investigated the key agreement and user authentication for cloud computing, these schemes cannot be directly applied to the fog computing due to efficiency and cost. To tackle this problem, we propose a secure and efficient key agreement and user authentication scheme for fog computing. Our scheme can establish secure sessions among different entities, and users can achieve cross-domain access to other fog server. Most importantly, Our scheme satisfies the perfect forward security and the complete anonymity. We prove that our scheme is secure in the random oracle model, and achieve formal security verification through the AVISPA tool. Finally, the performance analysis demonstrates that our scheme tends to be more efficient in comparison with similar schemes.\",\n \"Title: Deep Learning-Based Signal Detection with Soft Information for MISO-NOMA Systems\\nYear: 2021\\n\\nAbstract: This paper proposes a deep learning-based receiver scheme with soft information for uplink multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) systems, named by DLSI. In the proposed DLSI, we first perform QL-decomposition for channel matrix and iteratively construct the solution of the objective function for signal detection. Then deep neural networks (DNNs) are used to realize iteration steps and restore the symbols of the transmitted signals one by one. After all symbols of a user are detected, the successive interference cancellation (SIC) algorithm is used to detect the symbols of the next user. The output of each DNN is added with a soft decision layer, and the soft information will be input to the next DNN to improve the accuracy of training. Soft information contains more signal knowledge than hard decision, so it is also used in the SIC step, which reduces error propagation to a certain extent. Simulation results show that the performance of the DLSI is better than other deep learning methods.\",\n \"Title: HALT study on smart electricity meter\\nYear: 2017\\n\\nAbstract: Smart electricity meters (SEMs) play a very important role in our life, and their reliability has been increasingly emphasized by users, developers and manufacturers. To improve the reliability of SEMs, SEM enterprises have conducted a lots of activities related to reliability design, process control and test, etc. of SEMs; however, affected by many reasons, such as defects caused by raw materials, components and manufacturing process, and relatively extreme operating environment, SEMs are hard to achieve inherent reliability level of the original design. To meet the requirements for the time to market, performance of SEMs are required to be evaluated in the shortest time. The Highly Accelerated Life Test (HALT) has been widely used to obtain more reliability information in a short time by stimulating potential defects of products and shortening test duration, and now has become an important mean to evaluate product reliability. Therefore, HALT is an effective way to evaluate performance of SEMs, and the experimental method has been fully approved, promoted and widely used by SEM manufacturers at home and abroad. However, there is no unified HALT program for SEMs. The paper introduces research status of HALT on SEMs, the significance of HALT to improve the product reliability, terms and definitions related to HALT on SEMs, and provides detailed discussion on the way to carry out HALT experiment, including preparation, specification indexes of experiment parameters, requirements for capacity of experimental equipment, experimental steps and details; it has provided theoretical basis and operation guidance for HALT on SEMs. Finally, we conduct an HALT example according to the test methods to show that the poweron and meter reading item is the weakest part of SEM.\",\n \"Title: Weighted Mean Temperature Modelling Using Regional Radiosonde Observations for the Yangtze River Delta Region in China\\nYear: 2022\\n\\nAbstract: Precipitable water vapor can be estimated from the Global Navigation Satellite System (GNSS) signal's zenith wet delay (ZWD) by multiplying a conversion factor, which is a function of weighted mean temperature (T-m) over the GNSS station. Obtaining T-m is an important step in GNSS precipitable water vapor (PWV) conversion. In this study, aiming at the problem that T-m is affected by space and time, observations from seven radiosonde stations in the Yangtze River Delta region of China during 2015-2016 were used to establish both linear and nonlinear multifactor regional T-m model (RTM). Compared with the Bevis model, the results showed that the bias of yearly one-factor RTM, two-factor RTM and three-factor RTM was reduced by 0.55 K, 0.68 K and 0.69 K, respectively. Meanwhile, the RMSE of yearly one-factor, two-factor and three-factor RTM was reduced by 0.56 K, 0.80 K and 0.83 K, respectively. Compared with the yearly three-factor linear RTM, the mean bias and RMSE of the linear seasonal three-factor RTMs decreased by 0.06 K and 0.10 K, respectively. The precision of nonlinear seasonal three-factor RTMs is comparable to linear seasonal three-factor RTMs, but the expressions of the linear RTMs are easier to use. Therefore, linear seasonal three-factor RTMs are more suitable for calculating T-m and are recommended to use for PWV conversion in the Yangtze River Delta region.\",\n \"Title: Data-Driven Congestion Control of Micro Smart Sensor Networks for Transparent Substations\\nYear: 2021\\n\\nAbstract: Micro smart sensors and sensor networks are the key bases for building a fully visible, perceptible and controllable transparent substation in power grid. However, the massive deployment of micro smart sensors often leads to network congestion and directly affects the quality of information transmission. In practice, control design for micro sensor networks is often disturbed by factors such as nonlinearity, time delay and time-varying parameters, and the mathematical model is inaccurate. To solve these problems, this paper proposes a Koopman operator based data-driven congestion control scheme without using any system model information, based on model predictive control (MPC) and extended state observer (ESO). Firstly, according to the Koopman operator theory, a data-driven linear Koopman model for micro smart sensor networks is derived, only using the input/output data. Then an ESO based MPC scheme is designed to obtain the optimal packet dropping probability in the micro smart sensor node buffer area. Specifically, ESO performs real-time online estimation of the modeling errors, such as time-varying parameters, time delay and the external disturbances. Then the estimated modeling errors are viewed as total disturbances and are compensated in MPC, so that the queue length in the node buffer can quickly stabilize at the set value. Extensive simulations are conducted to verify the accuracy of Koopman model, and the effectiveness of the proposed control system design.\",\n \"Title: Design and Research of Symmetrical Multi-Throttle Thrust Hydrostatic Bearing Based on Comparative Analysis of Various Meshes\\nYear: 2022\\n\\nAbstract: Due to the advantages of high rotation accuracy and long life, hydrostatic air bearings are widely used in precision rotation equipment, such as machine tools and turntables. It is imperative to reasonably design the structural size of the bearing, especially as the size of the bearing in the precision turntable determines the bearing capacity of the turntable. At present, commercial CFD software is used chiefly for simulation verification for the design of air bearings. The mesh divided in the simulation calculation has a significant impact on the efficiency of the calculation and determines the accuracy of the final simulation results. Therefore, this paper takes the symmetrical multi-throttle thrust bearing in the precision turntable as the research object and compares and studies the advantages and disadvantages of sliced structured meshes, continuous structured meshes, and unstructured meshes. On this basis, simulation analysis of bearing capacity for different radial equalizing groove lengths, widths, and depths and explores the influence of the structure size of the thrust bearing on its bearing capacity. The study shows that the length and depth of the throttle groove significantly influence the bearing capacity, while the width has little influence on the bearing capacity. Therefore, under the specific cavity volume to ensure the dynamic characteristics of the bearing, the width of the throttling groove should be reduced first, and the length and depth of the throttling groove should be increased to improve the bearing capacity.\",\n \"Title: A New Cumulative Anomaly-Based Model for the Detection of Heavy Precipitation Using GNSS-Derived Tropospheric Products\\nYear: 2022\\n\\nAbstract: In recent years, tropospheric products obtained from ground-based global navigation satellite system (GNSS) measurements, especially the zenith total delay (ZTD) and precipitable water vapor (PWV) estimates, have advanced their usages in meteorological applications such as the detection of precipitation events. Generally, a cumulative anomaly (CA) time series of any atmospheric variable, which represents the long-term departure of the variable from its & x201C;normal & x201D; cycle, is widely used for quantitatively estimating the variable & x2019;s variations in response to a weather event. In this study, a new cumulative anomaly-based model (NCAM) containing 14 variables, including not only PWV and ZTD values but also their respective six types of derivatives, for detecting heavy precipitation was developed. The 6-h CA time series of the variables were calculated based on the data of hourly precipitation records and time series of ZTD and PWV collected at the co-located HKSC & x2013;King & x2019;s Park (KP) stations over the eight-year period 2010 & x2013;2017. The model was evaluated using the 14 variables & x2019; CA time series to detect heavy precipitation events happened in the summer months over the period 2018 & x2013;2019, and precipitation records in the same period were used as the reference. Results demonstrated that 99.1 & x0025; of heavy precipitation was correctly detected by the NCAM with a lead time of 2.87 h, and the false alarm ratio (FAR) score resulting from the model was reduced to 22.4 & x0025;. In addition, two case studies were also conducted to verify the effectiveness of the NCAM. These results all provide a promising direction for the application of using the CA time series of GNSS tropospheric products to the detection of heavy precipitation events.\",\n \"Title: An Exergoeconomic Analysis of a Gas-Type Industrial Drying System of Black Tea\\nYear: 2022\\n\\nAbstract: The performance evaluation and optimization of an energy conversion system design of an energy intensive drying system applied the method of combining exergy and economy is a theme of global concern. In this study, a gas-type industrial drying system of black tea with a capacity of 100 kg/h is used to investigate the exergetic and economic performance through the exergy and exergoeconomic methodology. The result shows that the drying rate of tea varies from the maximum value of 3.48 g(water)/g(dry matter) h to the minimum 0.18 g(water)/g(dry matter) h. The highest exergy destruction rate is found for the drying chamber (74.92 kW), followed by the combustion chamber (20.42 kW) in the initial drying system, and 51.83 kW and 21.15 kW in the redrying system. Similarly, the highest cost of the exergy destruction rate is found for the drying chamber (18.497 USD/h), followed by the combustion chamber (5.041 USD/h) in the initial drying system, and 12.796 USD/h and 5.222 USD/h in the redrying system. Furthermore, we analyzed the unit exergy rate consumed and the unit exergy cost of water removal in different drying sections of the drying system, and determined the optimal ordering of each component. These results mentioned above indicate that, whether from an energy or economic perspective, the component improvements should prioritize the drying chamber. Accordingly, minimizing exergy destruction and the cost of the exergy destruction rate can be considered as a strategy for improving the performance of energy and economy. Overall, the main results provide a more intuitive judgment for system improvement and optimization, and the exergy and exergoeconomic methodology can be commended as a method for agricultural product industrial drying from the perspective of exergoeconomics.\",\n \"Title: A Positivity Preserving, Energy Stable Finite Difference Scheme for the Flory-Huggins-Cahn-Hilliard-Navier-Stokes System\\nYear: 2022\\n\\nAbstract: In this paper, we propose and analyze a finite difference numerical scheme for the Cahn-Hilliard-Navier-Stokes system, with logarithmic Flory-Huggins energy potential. In the numerical approximation to the singular chemical potential, the logarithmic term and the surface diffusion term are implicitly updated, while an explicit computation is applied to the concave expansive term. Moreover, the convective term in the phase field evolutionary equation is approximated in a semi-implicit manner. Similarly, the fluid momentum equation is computed by a semi-implicit algorithm: implicit treatment for the kinematic diffusion term, explicit update for the pressure gradient, combined with semi-implicit approximations to the fluid convection and the phase field coupled term, respectively. Such a semi-implicit method gives an intermediate velocity field. Subsequently, a Helmholtz projection into the divergence-free vector field yields the velocity vector and the pressure variable at the next time step. This approach decouples the Stokes solver, which in turn drastically improves the numerical efficiency. The positivity-preserving property and the unique solvability of the proposed numerical scheme is theoretically justified, i.e., the phase variable is always between -1 and 1, following the singular nature of the logarithmic term as the phase variable approaches the singular limit values. In addition, an iteration construction technique is applied in the positivity-preserving and unique solvability analysis, motivated by the non-symmetric nature of the fluid convection term. The energy stability of the proposed numerical scheme could be derived by a careful estimate. A few numerical results are presented to validate the robustness of the proposed numerical scheme.\",\n \"Title: MFPSE: Multi-user Forward Private Searchable Encryption with dynamic authorization in cloud computing\\nYear: 2022\\n\\nAbstract: Dynamic Searchable Symmetric Encryption (DSSE) allows users to outsource data with ciphertext format to untrusted servers and supports the operations of data adding and deleting, which is adopted in common usage by government and business. Recently, the primitive of Forward Privacy in DSSE has drawn great public interest owing to its beneficial feature, which is that it can guard against the newly uploaded files from linking to previous search tokens. However, most of existing Forward Private Searchable Encryption (FPSE) schemes focus on single-user environment, which means that only the users themselves can utilize the data, greatly limits the wide application in cloud computing. To our knowledge, it is difficult to migrate the FPSE schemes to multi-user network. First, to realize forward privacy, the data owner should share the entire key group to the legitimate users, which means the users have the privilege of tampering or deleting data rather than query only; secondly, some FPSE schemes use the special structures and cannot be directly developed to multi-user network. Inspired by this, we present a scheme of multi-user forward private searchable encryption with dynamic authorization. The proposed scheme is based on a new structure of Multi-user State Chain and involves dynamic keyword-oriented authorization management. We prove our scheme can meet the secure characteristics, then conduct the performance evaluation and experiments. The results demonstrate that compared with the existing solutions, our scheme is superior in efficiency and practicability.\",\n \"Title: Temporal-Spatial Collaborative Mobile Edge Caching With User Satisfaction Awareness\\nYear: 2022\\n\\nAbstract: For mobile proactive edge caching problems, the hit action cannot always reflect the efficiency of the cache strategy unilaterally. Thus, the satisfaction information of users should be used to improve the intelligent cache strategy. Motivated by this, this paper focuses a caching scheme that jointly considers the cache evaluation both from the perspectives of the hit action and satisfaction of users (Algorithm 3). Accordingly, we first propose a requesting behavior prediction model (Algorithm 1) to handle the multiple content features. Then, a requesting behavior factor learning algorithm (Algorithm 2) based on the online gradient descent (OGD) with regulations is proposed to obtain the estimation of the parameters of the model in Algorithm 1. Further, the probabilistic tensor factorization learning (PTFL) model with collaborative filtering and Markov Chain Monte Carlo (MCMC) procedure are introduced for the learning process. Finally, the proposed the caching Algorithm 3 based on the hit action prediction and the collaborative temporal-spatial satisfaction learning scheme can be performed. Moreover, we theoretically combine the upper limit performance of user request prediction errors with the lower limit of user satisfaction of edge cache. The experimental results verify the effectiveness of the proposed algorithm.\",\n \"Title: A Comprehensive Study on Factors Affecting the Calibration of Potential Evapotranspiration Derived from the Thornthwaite Model\\nYear: 2022\\n\\nAbstract: Potential evapotranspiration (PET) is generally estimated using empirical models; thus, how to improve PET estimation accuracy has received widespread attention in recent years. Among all the models, although the temperature-driven Thornthwaite (TH) model is easy to operate, its estimation accuracy is rather limited. Although previous researchers proved that the accuracy of TH-PET can be greatly improved by using a limited number of variables to conduct calibration exercises, only preliminary experiments were conducted. In this study, to refine this innovation practice, we comprehensively investigated the factors that affect the calibration performances, including the selection of variables, seasonal effects, and spatial distribution of Global Navigation Satellite System (GNSS)/weather stations. By analyzing the factors and their effects, the following conclusions have been drawn: (1) an optimal variable selection scheme containing zenith total delay, temperature, pressure, and mean Julian Date was proposed; (2) the most salient improvements are in the winter and summer seasons, with improvement rates over 80%; (3) with the changes in horizontal (2.771-44.723 km) and height (1.239-344.665 m) differences among ten pairs of GNSS/weather stations, there are no obvious differences in the performances. These findings can offer an in-depth understanding of this practice and provide technical references to future applications.\",\n \"Title: An Improved Method for Rainfall Forecast Based on GNSS-PWV\\nYear: 2022\\n\\nAbstract: Global navigation satellite systems (GNSS) has been applied to the sounding of precipitable water vapor (PWV) due to its high accuracy and high spatiotemporal resolutions. PWV obtained from GNSS (GNSS-PWV) can be used to investigate extreme weather phenomena, such as the formation mechanism and prediction of rainfalls. In the study, a new, improved model for rainfall forecasting was developed based on GNSS data and rainfall data for the 9-year period from 2010 to 2018 at 66 stations located in the USA. The new model included three prediction factors-PWV value, PWV increase, maximum hourly PWV increase. The two key tasks involved for the development of the model were the determination of the thresholds for each prediction factor and the selection of the optimal strategy for using the three prediction factors together. For determining the thresholds, both critical success index (CSI) and true skill statistic (TSS) were tested, and results showed that TSS outperformed CSI for all rainfall events tested. Then, various strategies by combining the three prediction factors together were also tested, and results indicated that the best forecast result was from the case that any two of the prediction factors were over their own thresholds. Finally, the new model was evaluated using the GNSS data for the 2-year period from 2019 to 2020 at the above mentioned 66 stations, and the probability of detection (POD) and false-alarms rate (FAR) were adopted to measure the model performances. Over the 66 stations, the POD values ranged from 73% to 97% with the mean of 87%, and the FARs ranged from 26% to 77% with the mean of 53%. Moreover, it was also found that both POD and FAR values were related to the region of the station; e.g., the results at the stations that are located in humid regions were better than the ones located in dry regions. All these results suggest the feasibility and good performance of using GNSS-PWV for forecasting rainfall.\",\n \"Title: On Influencing Factors in Metaphor Variation for Five Elements Translation in TCM: A Binomial Logistic Regression Analysis\\nYear: 2022\\n\\nAbstract: Metaphor variation for English translations of Five Elements will impair the effect of Traditional Chinese Medicine (TCM) international communication. Few studies focus on contributing factors in metaphor variants for Five Elements translations. We model the binary designations for the Five-Element metaphor variants to analyze the internal and external language factors affecting the choice of ontological and structural metaphor, with the data from a corpus of six translations of the Inner Canon of Yellow Emperor. Statistical results unveil that the clause type, the syntax of Causer, language varieties, and the interaction of the clause type and language varieties significantly influence the metaphor variants. The complex interplay of the clause type and language varieties can explain people's cognitive differences in conceptualizing five elements. The study sheds light on the research of the Five Elements translation from the view of Construction Grammar and shows the benefit of machine learning technology for quantitatively describing and explaining the metaphor variation. It may hopefully uncover translators' cognitive mechanisms and pave a new way for TCM translation studies.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":75,"string":"75"}}},{"rowIdx":76,"cells":{"question_id":{"kind":"string","value":"Jos del R Mill n"},"question":{"kind":"string","value":"Generate an abstract for the title \"Brain-computer interaction\" using the following items: 1. Brain-Computer Interfaces (BCI)\n2. Human-Computer Interaction \n3. EEG Signals \n4. Brain-Actuated Applications \n5. Performance Improvement"},"answer":{"kind":"string","value":"The promise of Brain-Computer Interfaces (BCI) technology is to augment human capabilities by enabling people to interact with a computer through a conscious and spontaneous modulation of their brainwaves after a short training period. Indeed, by analyzing brain electrical activity online, several groups have designed brain-actuated systems that provide alternative channels for communication, entertainment and control. Thus, a person can write messages using a virtual keyboard on a computer screen and also browse the internet. Alternatively, subjects can operate simple computer games, or brain games, and interact with educational software. Researchers have also been able to train monkeys to move a computer cursor to desired targets and also to control a robot arm. Work with humans has shown that it is possible for them to move a cursor and even to drive a mobile robot between rooms in a house model. In this talk I will review the field of BCI, with a focus on non-invasive systems based on electroencephalogram (EEG) signals. I will also describe three brain-actuated applications we have developed: a virtual keyboard, a brain game, and a mobile robot (emulating a motorized wheelchair). Finally, we discuss current research directions we are pursuing in order to improve the performance and robustness of our BCI system, especially for real-time control of brain-actuated robots."},"correct_answer":{"kind":"string","value":"The promise of Brain-Computer Interfaces (BCI) technology is to augment human capabilities by enabling people to interact with a computer through a conscious and spontaneous modulation of their brainwaves after a short training period. Indeed, by analyzing brain electrical activity online, several groups have designed brain-actuated systems that provide alternative channels for communication, entertainment and control. Thus, a person can write messages using a virtual keyboard on a computer screen and also browse the internet. Alternatively, subjects can operate simple computer games, or brain games, and interact with educational software. Researchers have also been able to train monkeys to move a computer cursor to desired targets and also to control a robot arm. Work with humans has shown that it is possible for them to move a cursor and even to drive a mobile robot between rooms in a house model. In this talk I will review the field of BCI, with a focus on non-invasive systems based on electroencephalogram (EEG) signals. I will also describe three brain-actuated applications we have developed: a virtual keyboard, a brain game, and a mobile robot (emulating a motorized wheelchair). Finally, we discuss current research directions we are pursuing in order to improve the performance and robustness of our BCI system, especially for real-time control of brain-actuated robots."},"documents":{"kind":"list like","value":["Title: Brain-actuated interaction\nYear: 2004\n\nAbstract: Over the last years evidence has accumulated that shows the possibility to analyze human brain activity on-line and translate brain states into actions such as selecting a letter from a virtual keyboard or moving a robotics device. These initial results have been obtained with either invasive approaches (requiring surgical implantation of electrodes) or synchronous protocols (where brain signals are time-locked to external cues). In this paper we describe a portable noninvasive brain-computer interface that allows the continuous control of a mobile robot in a house-like environment and also the operation of a virtual keyboard. The interface works asynchronously (the person makes self-paced decisions on when to switch from one mental task to the next) and uses 8 surface electrodes to measure electroencephalogram signals from which a statistical classifier recognizes 3 different mental states. Here we report results with five volunteers during their brain-actuated interaction experiments with the mobile robot and the virtual keyboard. Two of the participants successfully moved the robot between several rooms, while the other three participants managed to write messages with the virtual keyboard. One of the latter volunteers is a physically impaired person suffering from spinal muscular atrophy.","Title: Activity Recognition in Opportunistic Sensor Environments.\nYear: 2011\n\nAbstract: OPPORTUNITY is project under the EU FET-Open funding11We acknowledge the support of the commission's research programme under under FET-Open grant number 225938. www.opportunity-project.eu. Contact author: Daniel Roggen, droggen@gmail.com in which we develop mobile systems to recognize human activity in dynamically varying sensor setups [1], [2]. The system autonomously discovers available sensors around the user and self-configures to recognize desired activities. It reconfigures itself as the environment changes, and encompasses principles supporting autonomous operation in open-ended environments. OPPORTUNITY mainstreams ambient intelligence and improves user acceptance by relaxing constraints on body-worn sensor characteristics, and eases the deployment in real-world environments. We summarize key achievements of the project so far. The project outcomes are robust activity recognition systems. This may enable smarter activity-aware energy-management in buildings, and advanced activity-aware health assistants.","Title: Ensemble creation and reconfiguration for activity recognition: An information theoretic approach.\nYear: 2011\n\nAbstract: Advances in sensing, portable computing devices, and wireless communication has lead to an increase in the number and variety of sensing enabled devices (e. g. smartphones or sensing garments). Pervasive computing and activity recognition systems should be able to take advantage of these sensors, even if they are not always available or appear in runtime. These sensors can be integrated into an ensemble that fuse their information to obtain the final decision. There is therefore a need for mechanisms to select which sensors should compose the ensemble, as well as techniques for dynamically reconfigure the ensemble so as to integrate new sensors.Sensors can be integrated into an ensemble where information from each of them is fused to obtain the final decisions. From the machine learning point of view, this corresponds to the combination of classifiers where measures of the accuracy and diversity of the ensemble are used to select the elements that may lead to the highest performance. Recent works propose measures of accuracy and diversity based on an information theoretical approach. In this paper we study the use of these measures for selecting ensembles in activity recognition based on body sensor networks. Besides a comparison with traditional diversity measures (e. g., Q-, kappa-statistics), we also present mechanisms to exploit these measures for the dynamic reconfiguration of the ensemble and detection of changes in the network.","Title: OPPORTUNITY: Towards opportunistic activity and context recognition systems\nYear: 2009\n\nAbstract: Opportunistic sensing allows to efficiently collect infor- mation about the physical world and the persons behav- ing in it. This may mainstream human context and activ- ity recognition in wearable and pervasive computing by re- moving requirements for a specific deployed infrastructure. In this paper we introduce the newly started European re- search project OPPORTUNITY within which we develop mobile opportunistic activity and context recognition sys- tems. We outline the project's objective, the approach we follow along opportunistic sensing, data processing and in- terpretation, and autonomous adaptation and evolution to environmental and user changes, and we outline prelimi- nary results.","Title: Person Authentication Using Brainwaves (EEG) and Maximum A Posteriori Model Adaptation\nYear: 2007\n\nAbstract: In this paper, we investigate the use of brain activity for person authentication. It has been shown in previous studies that the brain-wave pattern of every individual is unique and that the electroencephalogram (EEG) can be used for biometric identification. EEG-based biometry is an emerging research topic and we believe that it may open new research directions and applications in the future. However, very little work has been done in this area and was focusing mainly on person identification but not on person authentication. Person authentication aims to accept or to reject a person claiming an identity, i.e., comparing a biometric data to one template, while the goal of person identification is to match the biometric data against all the records in a database. We propose the use of a statistical framework based on Gaussian Mixture Models and Maximum A Posteriori model adaptation, successfully applied to speaker and face authentication, which can deal with only one training session. We perform intensive experimental simulations using several strict train/test protocols to show the potential of our method. We also show that there are some mental tasks that are more appropriate for person authentication than others.","Title: Interaction And Evaluation Of An Augmented Virtuality Assistance System For Teleoperated Robots\nYear: 2012\n\nAbstract: This paper presents the main features and capabilities of a developed system based on augmented virtuality (AV), which is devoted to the assisted navigation of teleoperated robots. The goal is to provide users with a greater perception of the robot navigation environment that improves the accuracy in teleoperation tasks and reduces the workload required to drive. The developed system is a mixed-perspective exocentric display (ME3D) type. In order to assess the work carried out, a comparative study between the developed ME3D interface and a video-centric display (VC2D) has been conducted. To this end, we have implemented both interfaces on a real robot and performed an experiment with 16 subjects in a real scenario. As a result, we have obtained a high degree of acceptance in the use of the ME3D interface by participants.","Title: REINFORCEMENT LEARNING OF GOAL-DIRECTED OBSTACLE-AVOIDING REACTION STRATEGIES IN AN AUTONOMOUS MOBILE ROBOT\nYear: 1995\n\nAbstract: In this paper we argue for building reactive autonomous mobile robots through reinforcement connectionist learning. Nevertheless, basic reinforcement learning is a slow process. This paper describes an architecture which deals with complex-high-dimensional and/or continuous-situation and action spaces effectively. This architecture is based on two main ideas. The first is to organize the reactive component into a set of modules in such a way that, roughly, each one of them codifies the prototypical action for a given cluster of situations. The second idea is to use a particular kind of planning for figuring out what part of the action space deserves attention for each cluster of situations. Salient features of the planning process are that it is grounded and that it is invoked only when the reactive component does not generalize correctly its previous experience to the new situation. We also report our experience in solving a basic task that most autonomous mobile robots must face, namely path finding.","Title: A Modular Reinforcement-Based Neural Controller For A Three-Link Manipulator\nYear: 1997\n\nAbstract: This paper presents a modular neural controller that learns goal-oriented obstacle-avoiding motion strategies for a sensor-based three-link planar robot arm. It acquires these strategies through reinforcement learning from focal sensory data. The controller has two reinforcement-based modules: a module for negotiating obstacles and a module for moving to the goal. Both modules generate actions that are interpreted with regard to a goal vector in the robot joint space. A differential inverse kinematics (DIV) module is used to obtain such a goal vector. The DIV module is based on the inversion of a neural network that has been previously trained to approximate the manipulator forward kinematics in polar coordinates. The controller achieves a satisfactory performance quite rapidly and shows good generalization capabilities in the face of new environments.","Title: A local neural classifier for the recognition of EEG patterns associated to mental tasks\nYear: 2002\n\nAbstract: This paper proposes a novel and simple local neural classifier for the recognition of mental tasks from on-line spontaneous EEG signals. The proposed neural classifier recognizes three mental tasks from on-line spontaneous EEG signals. Correct recognition is around 70%. This modest rate is largely compensated by two properties, namely low percentage of wrong decisions (below 5%) and rapid responses (every 1/2 s). Interestingly, the neural classifier achieves this performance with a few units, normally just one per mental task. Also, since the subject and his/her personal interface learn simultaneously from each other, subjects master it rapidly (in a few days of moderate training). Finally, analysis of learned EEG patterns confirms that for a subject to operate satisfactorily a brain interface, the latter must fit the individual features of the former","Title: Neural Approaches to Robot Control: Four Representative Applications\nYear: 1995\n\nAbstract: This paper reviews neural network techniques for achieving adaptivity in both manipulator and mobile robots. It is structured in two parts. First, the different learning approaches are classified according to the amount of training information they require: quantitative (supervised approaches), qualitative (reinforcement-based approaches) and none (unsupervised approaches). Afterwards, the adequacy of each approach for solving specific problems in robot control is illustrated through four working industrial prototypes developed by the authors in the frame of two Esprit projects. The problems tackled are the inverse kinematics and inverse dynamics of robot manipulators, visual robot positioning and mobile robot navigation.","Title: The Use of Brain-Computer Interfacing in Ambient Intelligence.\nYear: 2007\n\nAbstract: This paper is aimed to introduce IDIAP Brain Computer Interface (IBCI) research that successfully applied Ambience Intelligence (And) principles in designing intelligent brain-machine interactions. We proceed through (IBCI) applications describing how machines call decode and react to the human mental commands, cognitive and emotive states. We show how effective human-machine interaction for brain computer interfacing (BCI) can be achieved through, 1) asynchronous and spontaneous BCI, 2) shared control between the human and machine, 3) online learning and 4) the use of cognitive state recognition. Identifying common principles in BCI research and ambiance intelligence (AmI) research, we discuss IBCI applications. With the current studies oil recognition of human cognitive states, we argue for the possibility of designing empathic environments or devices that, have a better human like understanding directly from brain signals.","Title: The timing of exploratory decision-making revealed by single-trial topographic EEGanalyses.\nYear: 2012\n\nAbstract: Decision-making in an uncertain environment is driven by two major needs: exploring the environment to gather information or exploiting acquired knowledge to maximize reward. The neural processes underlying exploratory decision-making have been mainly studied by means of functional magnetic resonance imaging, overlooking any information about the time when decisions are made. Here, we carried out an electroencephalography (EEG) experiment, in order to detect the time when the brain generators responsible for these decisions have been sufficiently activated to lead to the next decision. Our analyses, based on a classification scheme, extract time-unlocked voltage topographies during reward presentation and use them to predict the type of decisions made on the subsequent trial. Classification accuracy, measured as the area under the Receiver Operator's Characteristic curve was on average 0.65 across 7 subjects. Classification accuracy was above chance levels already after 516ms on average, across subjects. We speculate that decisions were already made before this critical period, as confirmed by a positive correlation with reaction times across subjects. On an individual subject basis, distributed source estimations were performed on the extracted topographies to statistically evaluate the neural correlates of decision-making. For trials leading to exploration, there was significantly higher activity in dorsolateral prefrontal cortex and the right supramarginal gyrus; areas responsible for modulating behavior under risk and deduction. No area was more active during exploitation. We show for the first time the temporal evolution of differential patterns of brain activation in an exploratory decision-making task on a single-trial basis.","Title: Detecting and Rectifying Anomalies in Body Sensor Networks\nYear: 2011\n\nAbstract: Activity recognition using on body sensors are prone to degradation due to changes on sensor readings. The changes can occur because of degradation or alteration in the behaviour of the sensor with respect to the others. In this paper we propose a method which detects anomalous nodes in the network and takes compensatory actions to keep the performance of the system as high as possible while the system is running. We show on two activity datasets with different configurations of on body sensors that detection and compensation of anomalies make the system more robust against the changes.","Title: Bayesian Controller for a Novel Semi-Autonomous Navigation Concept.\nYear: 2007\n\nAbstract: This paper presents a novel concept of semi- autonomous navigation where a mobile robot evolves au- tonomously under the monitoring of a human user. The user provides corrective commands to the robot whenever he disagrees with the robot's navigational choices. These commands are not related to navigational values like directions or goals, but to the relevance of the robot's actions to the overall task. A binary error signal is used to correct the robot's decisions and to bring it to the desired goal location. This simple interface could easily be adapted to input systems designed for disabled people, offering them a convenient alternative to existing assisti ve systems. After a description of the whole concept, a special focus is given to the decisional process, which takes into account in a Bayesian way the environment perceived by the robot and the user generated signals in order to propose a navigational strategy to the human user. The strength and advantages of the proposed semi-autonomous concept are illustrated with two experiments.","Title: Fast recognition of anticipation-related potentials.\nYear: 2009\n\nAbstract: Anticipation increases the efficiency of daily tasks by partial advance activation of neural substrates involved in it. Here, we develop a method for the recognition of EEG correlates of this activation as early as possible on single trials, which is essential for brain-computer interaction. We explore various features from the EEG recorded in a contingent negative variation (CNV) paradigm. We als...","Title: Using Machine Learning Techniques in Real-World Mobile Robots\nYear: 1995\n\nAbstract: Applying machine learning techniques can help mobile robots meet the need for increased safety and adaptivity that real-world operation demands. The techniques also facilitate robot-to-user communication.Mobile robots are gradually leaving the laboratories and entering the real world. They are employed in automated factories, used for plant supervision, and are increasingly successful in service tasks such as health care. Almost 100 hospitals in the US and Europe use TRC's HelpMate, for example. However, if mobile robots are to find wide use in the real world, they must be able to learn from their experience. They must also be more adaptive, communicative, and safe.To meet these challenges, the complexity of the robot's control software must increase dramatically. The loop between the robot's perceptions and its actions must narrow on several levels of abstraction. This hierarchy of increasingly abstract situation-action rules must be grounded: it must map directly to the robot's basic sensing and motion capabilities. Building these rules requires that the knowledge related to both the task and the robot be codified.In addition, the robot's task specification must be accessible to the average user. The robot must learn to transform its own perceptions and actions into the user's language, and to compile the user's task specification into a set of directly executable commands. The omnipresent problems of symbol grounding and signal-to-symbol transformation become even more challenging if the robot is adapting its behavior according to both user needs and environmental changes.This article shows how machine learning techniques can help us meet these challenges. Using these techniques, we built increasingly abstract representations of a robot's perceptions and actions. This produced a symbolic description of what the robot knows and can do. Because this task is fairly complex, we first identified those subproblems that a learning method can solve efficiently, and isolated those with good classical solutions. Also, for a robot to solve a complex problem, we had to find solutions for several learning tasks. We identified these learning tasks and the learning techniques appropriate for their solution. To evaluate our approach, we used the mobile robots Priamos and Teseo.","Title: On the use of brain decoded signals for online user adaptive gesture recognition systems\nYear: 2010\n\nAbstract: Activity and context recognition in pervasive and wearable computing ought to continuously adapt to changes typical of open-ended scenarios, such as changing users, sensor characteristics, user expectations, or user motor patterns due to learning or aging. System performance inherently relates to the user's perception of the system behavior. Thus, the user should be guiding the adaptation process. This should be automatic, transparent, and unconscious. We capitalize on advances in electroencephalography (EEG) signal processing that allow for error related potentials (ErrP) recognition. ErrP are emitted when a human observes an unexpected behavior in a system. We propose and evaluate a hand gesture recognition system from wearable motion sensors that adapts online by taking advantage of ErrP. Thus the gesture recognition system becomes self-aware of its performance, and can self-improve through re-occurring detection of ErrP signals. Results show that our adaptation technique can improve the accuracy of a user independent gesture recognition system by 13.9% when ErrP recognition is perfect. When ErrP recognition errors are factored in, recognition accuracy increases by 4.9%. We characterize the boundary conditions of ErrP recognition guaranteeing beneficial adaptation. The adaptive algorithms are applicable to other forms of activity recognition, and can also use explicit user feedback rather than ErrP.","Title: Error-Related EEG Potentials Generated During Simulated Brain-Computer Interaction.\nYear: 2008\n\nAbstract: Brain-computer interfaces (BCIs) are prone to errors in the recognition of subject's intent. An elegant approach to improve the accuracy of BCIs consists in a verification procedure directly based on the presence of error-related potentials (ErrP) in the electroencephalogram (EEG) recorded right after the occurrence of an error. Several studies show the presence of ErrP in typical choice reaction ...","Title: Real-time prediction of fast and slow delivery of mental commands in a motor imagery BCI: An entropy-based approach\nYear: 2012\n\nAbstract: Providing adaptive shared control for Brain-Computer Interfaces (BCIs) can result in better performance while reducing the user's mental workload. In this respect, online estimation of accuracy and speed of command delivery are important factors. This study aims at real-time differentiation between fast and slow trials in a motor imagery BCI. In our experiments, we refer to trials shorter than the median of trial lengths as “fast” trials and to those longer than the median as “slow” trials. We propose a classifier for real-time distinction between fast and slow trials based on estimates of the entropy rates for the first 2-3 s of the electroencephalogram (EEG). Results suggest that it can be predicted whether a trial is slow or fast well before a cutoff time. This is important for adaptive shared control especially because 55% to 75% of trials (for the five subjects in this study) are longer than that cutoff time.","Title: Robust activity recognition combining anomaly detection and classifier retraining.\nYear: 2013\n\nAbstract: Activity recognition systems based on body-worn motion sensors suffer from a decrease in performance during the deployment and run-time phases, because of probable changes in the sensors (e.g. displacement or rotatation), which is the case in many real-life scenarios (e.g. mobile phone in a pocket). Existing approaches to achieve robustness tend to sacrifice information (e.g. by rotation-invariant features) or reduce the weight of the anomalous sensors at the classifier fusion stage (adaptive fusion), ignoring data which might still be perfectly meaningful, although different from the training data. We propose to use adaptation to rebuild the classifier models of the sensors which have changed position by a two-step approach: in the first step, we run an anomaly detection algorithm to automatically detect which sensors are delivering unexpected data; subsequently, we trigger a system self-training process, so that the remaining classifiers retrain the “anomalous” sensors. We show the benefit of this approach in a real activity recognition dataset comprising data from 8 sensors to recognize locomotion. The approach achieves similar accuracy compared to the upper baseline, obtained by retraining the anomalous classifiers on the new data.","Title: Robot arm reaching through neural inversions and reinforcement learning\nYear: 2000\n\nAbstract: We present a neural method that computes the inverse kinematics of any kind of robot manipulators; both redundant and non-redundant. Inverse kinematics solutions are obtained through the inversion of a neural network that has been previously trained to approximate the manipulator forward kinematics. The inversion provides difference vectors in the joint space from difference vectors in the workspace. Our differential inverse kinematics (DIV) approach can be viewed as a neural network implementation of the Jacobian transpose method for arm kinematic control that does not require previous knowledge of the arm forward kinematics. Redundancy can be exploited to obtain a special inverse kinematic solution that meets a particular constraint (e.g. joint limit avoidance) by inverting an additional neural network The usefulness of our DIV approach is further illustrated with sensor-based multilink manipulators that learn collision-free reaching motions in unknown environments. For this task, the neural controller has two modules: a reinforcement-based action generator (AG) and a DIV module that computes goal vectors in the joint space. The actions given by the AG are interpreted with regard to those goal vectors. (C) 2000 Published by Elsevier Science B.V. All rights reserved.","Title: Learning and Stabilization of Altruistic Behaviors in Multi-Agent System\nYear: 1997\n\nAbstract: Optimization of performance in collective systems often requires altruism. Emergence and stabilization of altruistic behaviors are difficult because the agents incur a cost when behaving altruistically. In this paper we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. Our multi-agent system is made up of autonomous agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learn stable altruistic behaviors, so reaching optimal (or near-to-optimal) performances in unknown and changing environments.","Title: Brain-Computer Interfacing for Intelligent Systems\nYear: 2008\n\nAbstract: Advances in cognitive neuroscience and brain-imaging technologies give us the unprecedented ability to interface directly with brain activity. These technologies let us monitor physical processes in the brain that correspond with certain forms of thought. Researchers have begun using these technologies to build brain-computer interfaces (BCIs)—communication systems that don't depend on the brain's normal output pathways of peripheral nerves and muscles. Four short articles provide a quick overview of the past, present, and future of BCIs.","Title: Brain---computer interfaces for space applications\nYear: 2011\n\nAbstract: Recent experiments have shown the possibility to use the brain electrical activity to directly control the movement of robots. Such a kind of brain---computer interface is a natural way to augment human capabilities by providing a new interaction link with the outside world and is particularly relevant as an aid for paralysed humans, although it also opens up new possibilities in human---robot interaction for able-bodied people. One of these new fields of application is the use of brain---computer interfaces in the space environment, where astronauts are subject to extreme conditions and could greatly benefit from direct mental teleoperation of external semi-automatic manipulators--for instance, mental commands could be sent without any output/latency delays, as it is the case for manual control in microgravity conditions. Previous studies show that there is a considerable potential for this technology onboard spacecraft.","Title: Brain-coupled interaction for semi-autonomous navigation of an assistive robot\nYear: 2010\n\nAbstract: This paper presents a novel semi-autonomous navigation strategy designed for low throughput interfaces. A mobile robot (e.g. intelligent wheelchair) proposes the most probable action, as analyzed from the environment, to a human user who can either accept or reject the proposition. In the case of refusal, the robot will propose another action, until both entities agree on what needs to be done. In an unknown environment, the robotic system first extracts features so as to recognize places of interest where a human-robot interaction should take place (e.g. crossings). Based on the local topology, relevant actions are then proposed, the user providing answers by means of a button or a brain-computer interface (BCI). Our navigation strategy is successfully tested both in simulation and with a real robot, and a feasibility study for the use of a BCI confirms the potential of such an interface.","Title: Temporal Processing of Brain Activity for the Recognition of EEG Patterns\nYear: 2002\n\nAbstract: This paper discusses three common strategies to incorporate temporal dynamics of brain activity to recognize 3 mental tasks from spontaneous EEG signals. The networks have been tested in a hard experimental setup; namely, generalization over different recording sessions while analyzing short time windows. It turns out that the simple local neural classifier currently embedded in our BCI, which averages the response to 8 consecutive EEG samples, is to be preferred to more complex time-processing networks such as TDNN and Elman-like. With this local classifier, users with some hours of training are able to operate several brain-actuated applications.","Title: Non-invasive brain-actuated control of a mobile robot\nYear: 2003\n\nAbstract: Recent experiments have indicated the possibility to use the brain electrical activity to directly control the movement of robotics or prosthetic devices. In this paper we report results with a portable non-invasive brain-computer interface that makes possible the continuous control of a mobile robot in a house-like environment. The interface uses 8 surface electrodes to measure electroencephalogram (EEG) signals from which a statistical classifier recognizes 3 different mental states. Until now, brain-actuated control of robots has relied on invasive approaches-requiring surgical implantation of electrodes-since EEG-based systems have been considered too slow for controlling rapid and complex sequences of movements. Here we show that, after a few days of training, two human subjects successfully moved a robot between several rooms by mental control only. Furthermore, mental control was only marginally worse than manual control on the same task.","Title: Neural Network Learning of Variable Grid-Based Maps for the Autonomous Navigation of Robots\nYear: 1997\n\nAbstract: This paper presents a map learning method that integrates the geometrical and topological paradigms. The geometrical component consists of a feed-forward neural network that interprets the robot's sensor readings efficiently. The topological map is created by learning a variable resolution partitioning of the world. Every partition corresponds to a perceptually homogeneous region. The efficiency of the learning process is based on the use of local memory-based techniques for partitioning and of active learning techniques for selecting the most appropriate region to be explored next. Finally, the paper reports experimental results obtained with the autonomous mobile robot TESEO.","Title: A comparative psychophysical and EEG study of different feedback modalities for HRI\nYear: 2008\n\nAbstract: This paper presents a comparison between six different ways to convey navigational information provided by a robot to a human. Visual, auditory, and tactile feedback modalities were selected and designed to suggest a direction of travel to a human user, who can then decide if he agrees or not with the robot's proposition. This work builds upon a previous research on a novel semi-autonomous navigation system in which the human supervises an autonomous system, providing corrective monitoring signals whenever necessary. We recorded both qualitative (user impressions based on selected criteria and ranking of their feelings) and quantitative (response time and accuracy) information regarding different types of feedback. In addition, a preliminary analysis of the influence of the different types of feedback on brain activity is also shown. The result of this study may provide guidelines for the design of such a human-robot interaction system, depending on both the task and the human user.","Title: Quantifying electrode reliability during brain-computer interface operation.\nYear: 2015\n\nAbstract: One of the problems of noninvasive brain-computer interface (BCI) applications is the occurrence of anomalous (unexpected) signals that might degrade BCI performance. This situation might slip the operator's attention since raw signals are not usually continuously visualized and monitored during BCI-actuated device operation. Anomalous data can for instance be the result of electrode misplacement, degrading impedance or loss of connectivity. Since this problem can develop at run time, there is a need of a systematic approach to evaluate electrode reliability during online BCI operation. In this paper, we propose two metrics detecting how much each channel is deviating from its expected behavior. This quantifies electrode reliability at run time which could be embedded into BCI data processing to increase performance. We assess the effectiveness of these metrics in quantifying signal degradation by conducting three experiments: Electrode swap, electrode manipulation, and offline artificially degradation of P300 signals.","Title: Prediction of command delivery time for BCI\nYear: 2014\n\nAbstract: One of the challenges in using brain computer interfaces over extended periods of time is the uncertainty in the system. This uncertainty can be due to the user's internal states, the non stationarity of the brain signals, or the variation of the class discriminative information over time. Therefore, the users are often unable to maintain the same accuracy and time efficiency in delivering BCI commands. In this paper, we tackle the issue of variation in BCI command delivery time for a motor imagery task with the aim of providing assistance through adaptive shared control. This is important mainly because having long delivery of mental commands leads to uncertainty in the user's intent classification and limits the responsiveness of the system. In order to address this issue, we separate the trials into long and short groups so that we have the same number of trials in each group. We demonstrate that using only a few samples at the beginning of the trial, we are able to predict whether the current trial will be short or long with high accuracies (70% - 86%). Eventually, this prediction enables us to tune the shared control parameters to overcome the issue of uncertainty.","Title: EEG correlates of active visual search during simulated driving: An exploratory study\nYear: 2014\n\nAbstract: Brain responses to visual stimuli can provide information about visual recognition processes. Several studies have shown stimulus-dependent modulation of the evoked neural responses after gaze shifts (i.e. eye fixation related potentials, EFRP) depending on the relevance of the fixated object. However these studies are typically performed on still images under constrained conditions. Here we extend this approach to study overt visual attention during a simulated driving task. Simultaneous analysis of eye-tracking and electroencephalography data revealed similar patterns than those previously reported. However, natural visual exploration yielded shorter fixations, which imposes constraints in the analysis of the elicited brain responses. Nevertheless, we found significant differences between EFRPs corresponding to target objects or non-object stimuli. These results suggest the possibility of decoding such information during driving, allowing better understanding of how drivers process the environmental information.","Title: Quantification and reduction of visual load during BCI operation\nYear: 2014\n\nAbstract: Operating a brain-actuated vehicle in real-world environments requires much of our visual attention. However, a typical brain-computer interface (BCI) sends the feedback information about the current status of the user's brain also via the visual channel. As a result, users have to split their visual attention into two: one for the surroundings and the other for the visual BCI feedback. Therefore, we recently developed a tactile stimulation system that successfully replaced the conventional visual feedback. Here we employ the multiple object tracking experiments to quantify the visual load added by the visual feedback. The result show that the additional visual load is almost eliminated, and the true negative rate of the BCI operation (intentional non-control) is improved when the visual feedback is replaced by the tactile feedback.","Title: Subject-oriented training for motor imagery brain-computer interfaces.\nYear: 2014\n\nAbstract: Successful operation of motor imagery (MI)-based brain-computer interfaces (BCI) requires mutual adaptation between the human subject and the BCI. Traditional training methods, as well as more recent ones based on co-adaptation, have mainly focused on the machine-learning aspects of BCI training. This work presents a novel co-adaptive training protocol shifting the focus on subject-related performances and the optimal accommodation of the interactions between the two learning agents of the BCI loop. Preliminary results with 8 able-bodied individuals demonstrate that the proposed method has been able to bring 3 naive users into control of a MI BCI within a few runs and to improve the BCI performances of 3 experienced BCI users by an average of 0.36 bits/sec.","Title: Phase-based features for motor imagery brain-computer interfaces.\nYear: 2011\n\nAbstract: Motor imagery (MI) brain-computer interfaces (BCIs) translate a subject's motor intention to a command signal. Most MI BCIs use power features in the mu or beta rhythms, while several results have been reported using a measure of phase synchrony, the phase-locking value (PLV). In this study, we investigated the performance of various phase-based features, including instantaneous phase difference (IPD) and PLV, for control of a MI BCI. Patterns of phase synchrony differentially appear over the motor cortices and between the primary motor cortex (M1) and supplementary motor area (SMA) during MI. Offline results, along with preliminary online sessions, indicate that IPD serves as a robust control signal for differentiating between MI classes, and that the phase relations between channels are relatively stable over several months. Offline and online trial-level classification accuracies based on IPD ranged from 84% to 99%, whereas the performance for the corresponding amplitude features ranged from 70% to 100%.","Title: Brain-controlled telepresence robot by motor-disabled people.\nYear: 2011\n\nAbstract: In this paper we present the first results of users with disabilities in mentally controlling a telepresence robot, a rather complex task as the robot is continuously moving and the user must control it for a long period of time (over 6 minutes) to go along the whole path. These two users drove the telepresence robot from their clinic more than 100 km away. Remarkably, although the patients had never visited the location where the telepresence robot was operating, they achieve similar performances to a group of four healthy users who were familiar with the environment. In particular, the experimental results reported in this paper demonstrate the benefits of shared control for brain-controlled telepresence robots. It allows all subjects (including novel BMI subjects as our users with disabilities) to complete a complex task in similar time and with similar number of commands to those required by manual control.","Title: Online modulation of the level of assistance in shared control systems\nYear: 2012\n\nAbstract: In this paper we propose a method to modulate the level of assistance provided by a shared controller, not only given the environmental context, but also according to the context of the user's current behaviour. We show that the enhanced situational context can be adequately captured by using online performance metrics (such as those more usually found in the evaluation of shared control systems). The resultant controller not only allows the user to perform better in the primary task (like many shared control systems), but has also has increased the level of user acceptance, due to the personalised dynamics of the control policy.","Title: The birth of the brain-controlled wheelchair\nYear: 2012\n\nAbstract: The prospect of controlling devices merely by the power of one's thoughts is compelling, especially for assistive technology applications. In the accompanying video, we show how we have strived to push brain-computer interface (BCI) technology out of the lab and into the real world, while simultaneously moving away from testing solely with healthy subjects to undertaking trials with patients and potential end-users. We describe the evolution of the motor imagery based BCI, which has resulted in a major milestone: the first patient trial of a motor imagery based BCI controlled wheelchair.","Title: Brain-Controlled Wheelchairs: A Robotic Architecture\nYear: 2013\n\nAbstract: Independent mobility is central to being able to perform activities of daily living by oneself. However, power wheelchairs are not an option for many people who, due to severe motor disabilities, are unable to use conventional controls. For some of these people, noninvasive brain-computer interfaces (BCIs) offer a promising solution to this interaction problem.","Title: Freeing the visual channel by exploiting vibrotactile BCI feedback.\nYear: 2013\n\nAbstract: Controlling a brain-actuated device requires the participant to look at and to split his attention between the interaction of the device with its environment and the status information of the Brain-Computer Interface (BCI). Such parallel visual tasks are partly contradictory, with the goal of achieving a good and natural device control. Is there a possibility to free the visual channel from one of these tasks? To address this, a stimulation system based on 6 coin-motors is developed, which provides a spatially continuous tactile illusion as BCI feedback, so that the visual channel can be devoted to the device. Several experiments are conducted in this work, to optimize the tactile illusion patterns and to investigate the influence on the electroencephalogram (EEG). Finally, 6 healthy BCI participants compare visual with tactile feedback in online BCI recordings. The developed stimulator can be used without interfering with the EEG. All subjects are able to perceive this type of tactile feedback well, and no statistical degradation in the online BCI performance could be identified between visual and tactile feedback.","Title: A hybrid BCI for enhanced control of a telepresence robot.\nYear: 2013\n\nAbstract: Motor-disabled end users have successfully driven a telepresence robot in a complex environment using a Brain-Computer Interface (BCI). However, to facilitate the interaction aspect that underpins the notion of telepresence, users must be able to voluntarily and reliably stop the robot at any moment, not just drive from point to point. In this work, we propose to exploit the user's residual muscular activity to provide a fast and reliable control channel, which can start/stop the telepresence robot at any moment. Our preliminary results show that not only does this hybrid approach increase the accuracy, but it also helps to reduce the workload and was the preferred control paradigm of all the participants.","Title: Offline decoding of upper limb muscle synergies from EEG slow cortical potentials.\nYear: 2013\n\nAbstract: Muscle synergies are thought to be the building blocks used by the central nervous system to control the underdetermined problem of muscles activation. Decoding these synergies from EEG could provide useful tools for BCI-controlled orthotic devices. In this paper, we assess the possibility of decoding muscle synergies from EEG slow cortical potentials in two healthy subjects and two stroke patients performing a center-out reaching task. We were able to successfully decode the extracted muscle synergies in both healthy subject and one patient.","Title: Steering timing prediction in a driving simulator task.\nYear: 2013\n\nAbstract: In this paper we present the preliminary results of a pioneering attempt to predict the timing of steering actions in a driving task from non-invasive EEG measurements. The experiment took place with the subjects driving a car at a constant speed on a simulated highway in a driving simulator. The EEG activity was analyzed during periods of straight driving and during lane change actions. Classifiers were built on the signals recorded over the motor areas for straight and pre-steering periods. The onset of the steering actions was detected on average 811 ms before the action with a 74.6% true positive rate.","Title: Towards Noninvasive Hybrid Brain–Computer Interfaces: Framework, Practice, Clinical Application, and Beyond\nYear: 2015\n\nAbstract: In their early days, brain-computer interfaces (BCIs) were only considered as control channel for end users with severe motor impairments such as people in the locked-in state. But, thanks to the multidisciplinary progress achieved over the last decade, the range of BCI applications has been substantially enlarged. Indeed, today BCI technology cannot only translate brain signals directly into control signals, but also can combine such kind of artificial output with a natural muscle-based output. Thus, the integration of multiple biological signals for real-time interaction holds the promise to enhance a much larger population than originally thought end users with preserved residual functions who could benefit from new generations of assistive technologies. A BCI system that combines a BCI with other physiological or technical signals is known as hybrid BCI (hBCI). In this work, we review the work of a large scale integrated project funded by the European commission which was dedicated to develop practical hybrid BCIs and introduce them in various fields of applications. This article presents an hBCI framework, which was used in studies with nonimpaired as well as end users with motor impairments.","Title: Very high frequency oscillations (VHFO) as a predictor of movement intentions.\nYear: 2006\n\nAbstract: Gamma band (30–80 Hz) oscillations arising in neuronal ensembles are thought to be a crucial component of the neural code. Recent studies in animals suggest a similar functional role for very high frequency oscillations (VHFO) in the range 80–200 Hz. Since some intracerebral studies in humans link VHFO to epileptogenesis, it remains unclear if VHFO appear in the healthy human brain and if so which is their role. This study uses EEG recordings from twelve healthy volunteers, engaged in a visuo-motor reaction time task, to show that VHFO are not necessarily pathological but rather code information about upcoming movements. Oscillations within the range (30–200 Hz) occurring in the period between stimuli presentation and the fastest hand responses allow highly accurate (>96%) prediction of the laterality of the responding hand in single trials. Our results suggest that VHFO belong in functional terms to the gamma band that must be considerably enlarged to better understand the role of oscillatory activity in brain functioning. This study has therefore important implications for the recording and analysis of electrophysiological data in normal subjects and patients.","Title: Detection Of Anticipatory Brain Potentials During Car Driving\nYear: 2012\n\nAbstract: Recognition of driver's intention from electroencephalogram (EEG) can be helpful in developing an in-car brain computer interface (BCI) systems for intelligent cars. This could be beneficial in enhancing the quality of interaction between the driver and the car to provide the response of the intelligent cars in line with driver's intention. We proposed investigating anticipation as the cognitive state leading to specific actions during car driving. An experimental protocol is designed for recording EEG from 6 subjects while driving the virtual reality driving simulator. The experimental protocol is a variant of the contingent negative variation (CNV) paradigm with Go and No-go conditions in driving framework. The results presented in this study support the presence of the slow cortical anticipatory potentials in EEG grand averages and also confirm the discriminability of these potentials in offline single trial classification with the average of 0.76 +/- 0.12 in area under the curve (AUC).","Title: Anticipation- And Error-Related Eeg Signals During Realistic Human-Machine Interaction: A Study On Visual And Tactile Feedback\nYear: 2012\n\nAbstract: The exploitation of EEG signatures of cognitive processes can provide valuable information to improve interaction with brain actuated devices. In this work we study these correlates in a realistic situation simulated in a virtual reality environment. We focus on cortical potentials linked to the anticipation of future events (i.e. the contingent negative variation, CNV) and error-related potentials elicited by both visual and tactile feedback. Experiments with 6 subjects show brain activity consistent with previous studies using simpler stimuli, both at the level of ERPs and single trial classification. Moreover, we observe comparable signals irrespective of whether the subject was required to perform motor actions. Altogether, these results support the possibility of using these signals for practical brain machine interaction.","Title: Improved Recognition Of Error Related Potentials Through The Use Of Brain Connectivity Features\nYear: 2012\n\nAbstract: Brain error processing plays a key role in goal-directed behavior and learning in human brain. Directed transfer function (DTF) on EEG signal brings unique features for discrimination between correct and error cases in brain-computer interface (BCI) system. We describe the first application of brain connectivity features for recognizing error-related signals in non-invasive BCI. EEG signal were recorded from 16 human subjects when they monitored stimuli moving in either correct or erroneous direction. Classification performance using waveform features, brain connectivity features and their combination were compared. The result of combined features yielded highest classification accuracy, 0.85. In addition, we also show that brain connectivity at theta band around 200ms after stimuli carry highly discriminant information between error and correct trials. This paper provides evidence that the use of connectivity features improve the performance of an EEG based BCI.","Title: Adaptive Assistance for Brain-Computer Interfaces by Online Prediction of Command Reliability\nYear: 2016\n\nAbstract: Abstract-One of the challenges of using brain-computer interfaces (BCIs) over extended periods of time is the variation of the users' performance from one experimental day to another. The goal of the current study is to propose a performance estimator for an electroencephalography-based motor imagery BCI by assessing the reliability of a command (i.e., predicting a 'short' or 'long' command delivery time, CDT). Using a short time window (<1.5 s, shorter than the delivery time) of the mental task execution and a linear discriminant analysis classifier, we could reliably differentiate between short and long CDT (Area under the sensitivity-specificity curve, AUC . 0.8) for 9 healthy subjects. Moreover, we assessed the feasibility of providing online adaptive assistance using the performance estimator in a BCI game by comparing two conditions: (i) allowing a 'fixed timeout' to deliver each command or (ii) providing 'adaptive assistance' by giving more time if the performance estimator detects a long CDT. The results revealed that providing adaptive assistance increases the ratio of correct commands significantly cantly (p <0.01). Moreover, the task load index (measured via the NASA TLX questionnaire) shows a significantly higher user acceptance in case of providing adaptive assistance (p <0.01). Furthermore, the results obtained in this study were used to simulate a robotic navigation scenario, which showed how adaptive assistance improved performance.","Title: Context-based filtering for assisted brain-actuated wheelchair driving\nYear: 2007\n\nAbstract: Controlling a robotic device by using human brain signals is an interesting and challenging task. The device may be complicated to control and the nonstationary nature of the brain signals provides for a rather unstable input. With the use of intelligent processing algorithms adapted to the task at hand, however, the performance can be increased. This paper introduces a shared control system that helps the subject in driving an intelligent wheelchair with a noninvasive brain interface. The subject's steering intentions are estimated from electroencephalogram (EEG) signals and passed through to the shared control system before being sent to the wheelchair motors. Experimental results show a possibility for significant improvement in the overall driving performance when using the shared control system compared to driving without it. These results have been obtained with 2 healthy subjects during their first day of training with the brain-actuated wheelchair.","Title: Discriminant brain connectivity patterns of performance monitoring at average and single-trial levels.\nYear: 2015\n\nAbstract: Electrophysiological and neuroimaging evidence suggest the existence of common mechanisms for monitoring erroneous events, independent of the source of errors. Previous works have described modulations of theta activity in the medial frontal cortex elicited by either self-generated errors or erroneous feedback. In turn, similar patterns have recently been reported to appear after the observation of external errors. We report cross-regional interactions after observation of errors at both average and single-trial levels. We recorded scalp electroencephalography (EEG) signals from 15 subjects while monitoring the movement of a cursor on a computer screen. Connectivity patterns, estimated using multivariate auto-regressive models, show increased error-related modulations of the information transfer in the theta and alpha bands between frontocentral and frontolateral areas. Conversely, a decrease of connectivity in the beta band is also observed. These network patterns are similar to those elicited by self-generated errors. However, since no motor response is required, they appear to be related to intrinsic mechanisms of error processing, instead of being linked to co-activation of motor areas. Noticeably, we demonstrate that cross-regional interaction patterns can be estimated on a trial-by-trial basis. These trial-specific patterns, consistent with the multi-trial analysis, convey discriminant information on whether a trial was elicited by observation of an erroneous action. Overall, our study supports the role of frequency-specific modulations in the medial frontal cortex in coordinating cross-regional activity during cognitive monitoring at a single-trial basis.","Title: Towards Independence: A BCI Telepresence Robot for People With Severe Motor Disabilities\nYear: 2015\n\nAbstract: This paper presents an important step forward towards increasing the independence of people with severe motor disabilities, by using brain-computer interfaces to harness the power of the Internet of Things. We analyze the stability of brain signals as end-users with motor disabilities progress from performing simple standard on-screen training tasks to interacting with real devices in the real world. Furthermore, we demonstrate how the concept of shared control-which interprets the user's commands in context-empowers users to perform rather complex tasks without a high workload. We present the results of nine end-users with motor disabilities who were able to complete navigation tasks with a telepresence robot successfully in a remote environment (in some cases in a different country) that they had never previously visited. Moreover, these end-users achieved similar levels of performance to a control group of 10 healthy users who were already familiar with the environment.","Title: Making The Most Of Context-Awareness In Brain-Computer Interfaces\nYear: 2013\n\nAbstract: In order for brain-computer interfaces (BCIs) to be used reliably for extended periods of time, they must be able to adapt to the users evolving needs. This adaptation should not only be a function of the environmental (external) context, but should also consider the internal context, such as cognitive states and brain signal reliability. In this work, we propose three different shared control frameworks that have been used for BCI applications: contextual fusion, contextual gating, and contextual regulation. We review recently published results in the light of these three context-awareness frameworks. Then, we discuss important issues to consider when designing a shared controller for BCI.","Title: Brain Correlates Of Lane Changing Reaction Time In Simulated Driving\nYear: 2015\n\nAbstract: Psychophysical studies have reported correlation between neural activity in frontal and parietal areas and subject's reaction time in simple tasks. Here we study whether similar correlates can also be identified in driver's electroencephalography (EEG) activity when they perform steering actions triggered by exogenous stimuli (e.g. obstacles along the road). We report analysis of the EEG signals of fifteen subjects while they drive in a realistic car simulator. We found that the peak latency of the event-related potentials in frontal and parietal areas significantly correlates with the onset of the steering behavior. Similarly, modulations of the power in the theta band (4-8 Hz) prior to the action also correlates with the reaction times. These results provide evidence of reliable neural markers of the driver's response variability.","Title: Stream fusion for multi-stream automatic speech recognition.\nYear: 2016\n\nAbstract: Multi-stream automatic speech recognition (MS-ASR) has been confirmed to boost the recognition performance in noisy conditions. In this system, the generation and the fusion of the streams are the essential parts and need to be designed in such a way to reduce the effect of noise on the final decision. This paper shows how to improve the performance of the MS-ASR by targeting two questions; (1) How many streams are to be combined, and (2) how to combine them. First, we propose a novel approach based on stream reliability to select the number of streams to be fused. Second, a fusion method based on Parallel Hidden Markov Models is introduced. Applying the method on two datasets (TIMIT and RATS) with different noises, we show an improvement of MS-ASR.","Title: Spatial filters yield stable features for error-related potentials across conditions\nYear: 2016\n\nAbstract: Error-related potentials (ErrP) have been increasingly studied in psychophysical experiments as well as for brain-machine interfacing. In the latter case, the generalisation capabilities of ErrP decoders is a crucial element to avoid frequent recalibration processes, thus increasing their usability. Previous studies have suggested that ErrP signals are rather stable across recording sessions. Also, studies using protocols of serial stimuli presentation show that these potentials do not change significantly with the presentation rate. Here we complement these studies by analysing the decoding generalisation capabilities. Using data from monitoring experiments, we evaluate how much the performance degrades when tested in a condition different than the one the decoder was trained with. Moreover, we compare different spatial filtering techniques to see which preprocessing steps yield less-sensitive features for ErrP decoding.","Title: Evaluating decoding performance of upper limb imagined trajectories during center-out reaching tasks\nYear: 2016\n\nAbstract: In recent years, several studies have shown that there is a correlation between electroencephalographic (EEG) signals and hand-reaching kinematic parameters after applying linear decoders. These studies have been generally conducted using actual upper limb movements, but so far there has been little discussion about the possibility of applying these decoders to motor imagery tasks. Moreover, the use of these decoders is rather controversial and there is no general agreement about the metrics used to compare decoded and real kinematics. In this paper, we have applied this methodology to upper limb imagined movements using a center-out protocol. Our results show that, although decoding performance is poor, there are significant components, particularly in horizontal imagined movements, that could be translated into reliable output commands. For this purpose, we have proposed a discrete classification of reached targets showing significant classification rates when the number of classified targets decreases.","Title: Superposition Model For Steady State Visually Evoked Potentials\nYear: 2016\n\nAbstract: Steady State Visually Evoked Potentials (SSVEP) are signals produced in the occipital part of the brain when someone gaze a light flickering at a fixed frequency. These signals have been used for Brain Machine Interfacing (BMI), where one or more stimuli are presented and the system has to detect what is the stimulus the user is attending to. It has been proposed that the SSVEP signal is produced by superposition of Visually Evoked Potentials (VEP) but there is not a model that shows that. We propose a model for a SSVEP signal that is a superposition of the response due to the rising and falling edges of the stimulus and that can be calculated for different frequencies.We fixed the model for 4 subjects that gazed stimuli in the frequencies of 9Hz, 11Hz, 13Hz and 15Hz, and duty-cycles of 20%, 35%, 50%, 65%, and 80%. Since the phases of SSVEP signals are stable over the time, these were used to fix the model, without the amplitude; however, signals of scattered phases were discarded. The model parameters were found using the Oz electrode signals and a genetic algorithm.The mean absolute error (MAE) between the measured phase and the obtained one was calculated for each subject (named S1, S2, S3, and S4). The model was fixed for the subjects in the fundamental frequencies, just two of them in the second harmonic, and one in the third harmonic. We obtained a maximum MAE for 3 subjects (S1, S2, and S4) in the fundamental frequencies at 0.30 rad and one of them (S2) with 0.21 rad in the second harmonic. The last one (S3) signals show poor results with a MAE between 0.46 rad and 1.79 rad by including fundamental frequencies, and second and third harmonics. The results show similarities among the different model parameters such that it suggests that a general model could be obtained.","Title: A brain-controlled exoskeleton with cascaded event-related desynchronization classifiers.\nYear: 2017\n\nAbstract: This paper describes a brainmachine interface for the online control of a powered lower-limb exoskeleton based on electroencephalogram (EEG) signals recorded over the users sensorimotor cortical areas. We train a binary decoder that can distinguish two different mental states, which is applied in a cascaded manner to efficiently control the exoskeleton in three different directions: walk front, turn left and turn right. This is realized by first classifying the users intention to walk front or change the direction. If the user decides to change the direction, a subsequent classification is performed to decide turn left or right. The users mental command is conditionally executed considering the possibility of obstacle collision. All five subjects were able to successfully complete the 3-way navigation task using brain signals while mounted in the exoskeleton. We observed on average 10.2% decrease in overall task completion time compared to the baseline protocol.","Title: Plug&Play Brain-Computer Interfaces for effective Active and Assisted Living control.\nYear: 2017\n\nAbstract: Brain-Computer Interfaces (BCI) rely on the interpretation of brain activity to provide people with disabilities with an alternative/augmentative interaction path. In light of this, BCI could be considered as enabling technology in many fields, including Active and Assisted Living (AAL) systems control. Interaction barriers could be removed indeed, enabling user with severe motor impairments to gain control over a wide range of AAL features. In this paper, a cost-effective BCI solution, targeted (but not limited) to AAL system control is presented. A custom hardware module is briefly reviewed, while signal processing techniques are covered in more depth. Steady-state visual evoked potentials (SSVEP) are exploited in this work as operating BCI protocol. In contrast with most common SSVEP-BCI approaches, we propose the definition of a prediction confidence indicator, which is shown to improve overall classification accuracy. The confidence indicator is derived without any subject-specific approach and is stable across users: it can thus be defined once and then shared between different persons. This allows some kind of Plug&Play interaction. Furthermore, by modelling rest/idle periods with the confidence indicator, it is possible to detect active control periods and separate them from \"background activity\": this is capital for real-time, self-paced operation. Finally, the indicator also allows to dynamically choose the most appropriate observation window length, improving system's responsiveness and user's comfort. Good results are achieved under such operating conditions, achieving, for instance, a false positive rate of 0.16 min, which outperform current literature findings.","Title: mano: A Wearable Hand Exoskeleton for Activities of Daily Living and Neurorehabilitation.\nYear: 2018\n\nAbstract: Hand sensorimotor impairments are among the most common consequences of injuries affecting the central and peripheral nervous systems, leading to a drastic reduction in the quality of life for affected individuals. Combining wearable robotic exoskeletons and human-machine interfaces is a promising avenue for the restoration and substitution of lost and impaired functions for these users. In this s...","Title: ROS-health: An open-source framework for neurorobotics\nYear: 2018\n\nAbstract: This paper aims at providing a preliminary description of ROS-Health, a novel framework for neurorobotics based on the middleware Robot Operating System (ROS). The increased interest in the neurorobotics field and the proliferation of several (neuro)physiological-based applications to control robotics devices made clear the importance to establish a standardized research platform in order to facilitate the distribution of the software, the replication of experimental results and the creation of an unified community to share and manage the code in the years. For this reason, we propose a common platform developed in the ROS ecosystem that takes advantage of its tools and capabilities. Furthermore, we describe the design guidelines that we are following in the preliminary definition of ROS-Health architecture. Finally, we present two illustrative use cases that highlight the advantages and benefits of the adoption of ROS-Health.","Title: Sensory threshold neuromuscular electrical stimulation fosters motor imagery performance.\nYear: 2018\n\nAbstract: Motor imagery (MI) has been largely studied as a way to enhance motor learning and to restore motor functions. Although it is agreed that users should emphasize kinesthetic imagery during MI, recordings of MI brain patterns are not sufficiently reliable for many subjects. It has been suggested that the usage of somatosensory feedback would be more suitable than standardly used visual feedback to enhance MI brain patterns. However, somatosensory feedback should not interfere with the recorded MI brain pattern. In this study we propose a novel feedback modality to guide subjects during MI based on sensory threshold neuromuscular electrical stimulation (St-NMES). St-NMES depolarizes sensory and motor axons without eliciting any muscular contraction. We hypothesize that St-NMES does not induce detectable ERD brain patterns and fosters MI performance. Twelve novice subjects were included in a cross-over design study. We recorded their EEG, comparing St-NMES with visual feedback during MI or resting tasks. We found that St-NMES not only induced significantly larger desynchronization over sensorimotor areas (p<0.05) but also significantly enhanced MI brain connectivity patterns. Moreover, classification accuracy and stability were significantly higher with St-NMES. Importantly, St-NMES alone did not induce detectable artifacts, but rather the changes in the detected patterns were due to an increased MI performance. Our findings indicate that St-NMES is a promising feedback in order to foster MI performance and cold be used for BMI online applications.","Title: Decoding Neural Correlates of Cognitive States to Enhance Driving Experience.\nYear: 2018\n\nAbstract: Modern cars can support their drivers by assessing and autonomously performing different driving maneuvers based on information gathered by in-car sensors. We propose that brain- machine interfaces (BMIs) can provide complementary information that can ease the interaction with intelligent cars in order to enhance the driving experience. In our approach, the human remains in control, while a BMI is...","Title: Motor Attempt EEG Paradigm as a Diagnostic Tool for Disorders of Consciousness.\nYear: 2018\n\nAbstract: To investigate whether a motor attempt EEG paradigm coupled with functional electrical stimulation can detect command following and, therefore, signs of conscious awareness in patients with disorders of consciousness, we recorded nine patients admitted to acute rehabilitation after a brain lesion. We extracted peak classification accuracy and peak session discriminant power (PSDP) and we assessed their correlation to the established coma recovery scale revised (CRS-R) and the agreement with diagnosis based on the novel motor behavior tool (MBT). Only PSDP correlated significantly with CRS-R and it also outperformed peak accuracy regarding the MBT. We conclude that PSDP might be more suitable than accuracy to complement CRS-R and MBT in evaluating ambiguous cases and in detecting cognitive motor dissociation.","Title: Using Robust Principal Component Analysis to Reduce EEG Intra-Trial Variability.\nYear: 2018\n\nAbstract: Practical brain-computer interfaces need to overcome several challenges, including tolerance to signal variability within- and across sessions. We introduce Robust Principal Component Analysis (RPCA) as a potential approach to tackle intra-trial variability. Assuming that subjects undergo the same cognitive process or perform the same task in a short period (e.g., a few seconds), as a result, the signal of interest should be represented by only a few components. We verified this approach on a workload detection task, where subjects needed to pilot a simulated drone. We used RPCA as a processing step to decrease trial variability and assessed its impact on classification accuracy. Our results showed that RPCA significantly increased performance in both at group and subject level analysis. On average, class-balanced accuracy when simulating RPCA online increased from 63.9% up to 70.6% $(p~ 0 . 001)$.","Title: Exploring Embedding Methods in Binary Hyperdimensional Computing: A Case Study for Motor-Imagery based Brain-Computer Interfaces.\nYear: 2018\n\nAbstract: Key properties of brain-inspired hyperdimensional (HD) computing make it a prime candidate for energy-efficient and fast learning in biosignal processing. The main challenge is however to formulate embedding methods that map biosignal measures to a binary HD space. In this paper, we explore variety of such embedding methods and examine them with a challenging application of motor imagery brain-computer interface (MI-BCI) from electroencephalography (EEG) recordings. We explore embedding methods including random projections, quantization based thermometer and Gray coding, and learning HD representations using end-to-end training. All these methods, differing in complexity, aim to represent EEG signals in binary HD space, e.g. with 10,000 bits. This leads to development of a set of HD learning and classification methods that can be selectively chosen (or configured) based on accuracy and/or computational complexity requirements of a given task. We compare them with state-of-the-art linear support vector machine (SVM) on an NVIDIA TX2 board using the 4-class BCI competition IV-2a dataset as well as a new 3-class dataset. Compared to SVM, results on 3-class dataset show that simple thermometer embedding achieves moderate average accuracy (79.56% vs. 82.67%) with 26.8$times$ faster training time and 22.3$times$ lower energy; on the other hand, switching to end-to-end training with learned HD representations wipes out these training benefits while boosting the accuracy to 84.22% (1.55% higher than SVM). Similar trend is observed on the 4-class dataset where SVM achieves on average 74.29%: the thermometer embedding achieves 89.9$times$ faster training time and 58.7$times$ lower energy, but a lower accuracy (67.09%) than the learned representation of 72.54%.","Title: Hyperdimensional Computing for Blind and One-Shot Classification of EEG Error-Related Potentials\nYear: 2020\n\nAbstract: The mathematical properties of high-dimensional (HD) spaces show remarkable agreement with behaviors controlled by the brain. Computing with HD vectors, referred to as “hypervectors,” is a brain-inspired alternative to computing with numbers. HD computing is characterized by generality, scalability, robustness, and fast learning, making it a prime candidate for utilization in application domains such as brain–computer interfaces. We describe the use of HD computing to classify electroencephalography (EEG) error-related potentials for noninvasive brain–computer interfaces. Our algorithm naturally encodes neural activity recorded from 64 EEG electrodes to a single temporal–spatial hypervector without requiring any electrode selection process. This hypervector represents the event of interest, can be analyzed to identify the most discriminative electrodes, and is used for recognition of the subject’s intentions. Using the full set of training trials, HD computing achieves on average 5% higher single-trial classification accuracy compared to a conventional machine learning method on this task (74.5% vs. 69.5%) and offers further advantages: (1) Our algorithm learns fast: using only 34% of training trials it achieves an average accuracy of 70.5%, surpassing the conventional method. (2) Conventional method requires prior domain expert knowledge, or a separate process, to carefully select a subset of electrodes for a subsequent preprocessor and classifier, whereas our algorithm blindly uses all 64 electrodes, tolerates noises in data, and the resulting hypervector is intrinsically clustered into HD space; in addition, most preprocessing of the electrode signal can be eliminated while maintaining an average accuracy of 71.7%.","Title: Human EEG reveals distinct neural correlates of power and precision grasping types.\nYear: 2018\n\nAbstract: Hand grasping is a sophisticated motor task that has received much attention by the neuroscientific community, which demonstrated how grasping activates a network involving parietal, pre-motor and motor cortices using fMRI, ECoG, LFPs and spiking activity. Yet, there is a need for a more precise spatio-temporal analysis as it is still unclear how these brain activations over large cortical areas evolve at the sub-second level. In this study, we recorded ten human participants (1 female) performing visually-guided, self-paced reaching and grasping with precision or power grips. Following the results, we demonstrate the existence of neural correlates of grasping from broadband EEG in self-paced conditions and show how neural correlates of precision and power grasps differentially evolve as grasps unfold. 100 ms before the grasp is secured, bilateral parietal regions showed increasingly differential patterns. Afterwards, sustained differences between both grasps occurred over the bilateral motor and parietal regions, and medial pre-frontal cortex. Furthermore, these differences were sufficiently discriminable to allow single-trial decoding with 70% decoding performance. Functional connectivity revealed differences at the network level between grasps in fronto-parietal networks, in terms of upper-alpha cortical oscillatory power with a strong involvement of ipsilateral hemisphere. Our results supported the existence of fronto-parietal recurrent feedback loops, with stronger interactions for precision grips due to the finer motor control required for this grasping type.","Title: Non-invasive estimation of local field potentials for neuroprosthesis control\nYear: 2005\n\nAbstract: Recent experiments have shown the possibility of using the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions, i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using an identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using a different number of electrodes.","Title: Reliable decoding of motor state transitions during imagined movement\nYear: 2019\n\nAbstract: Current non-invasive Brain Machine interfaces commonly rely on the decoding of sustained motor imagery activity. This approach enables a user to control brain-actuated devices by triggering predetermined motor actions. However, despite of its broad range of applications, this paradigm has failed so far to allow a natural and reliable control. As an alternative approach, we investigated the decoding of states transitions of an imagined movement, i.e. rest-to-movement (onset) and movement-to-rest (offset). We show that both transitions can be reliably decoded with accuracies of 71.47% for the onset and 73.31% for the offset (N = 9 subjects). Importantly, these transitions exhibit different neural patterns and need to be decoded independently. Our results indicate that both decoders are able to capture the brain dynamics during imagined movements and that their combined use could provide benefits in terms of accuracy and time precision."],"string":"[\n \"Title: Brain-actuated interaction\\nYear: 2004\\n\\nAbstract: Over the last years evidence has accumulated that shows the possibility to analyze human brain activity on-line and translate brain states into actions such as selecting a letter from a virtual keyboard or moving a robotics device. These initial results have been obtained with either invasive approaches (requiring surgical implantation of electrodes) or synchronous protocols (where brain signals are time-locked to external cues). In this paper we describe a portable noninvasive brain-computer interface that allows the continuous control of a mobile robot in a house-like environment and also the operation of a virtual keyboard. The interface works asynchronously (the person makes self-paced decisions on when to switch from one mental task to the next) and uses 8 surface electrodes to measure electroencephalogram signals from which a statistical classifier recognizes 3 different mental states. Here we report results with five volunteers during their brain-actuated interaction experiments with the mobile robot and the virtual keyboard. Two of the participants successfully moved the robot between several rooms, while the other three participants managed to write messages with the virtual keyboard. One of the latter volunteers is a physically impaired person suffering from spinal muscular atrophy.\",\n \"Title: Activity Recognition in Opportunistic Sensor Environments.\\nYear: 2011\\n\\nAbstract: OPPORTUNITY is project under the EU FET-Open funding11We acknowledge the support of the commission's research programme under under FET-Open grant number 225938. www.opportunity-project.eu. Contact author: Daniel Roggen, droggen@gmail.com in which we develop mobile systems to recognize human activity in dynamically varying sensor setups [1], [2]. The system autonomously discovers available sensors around the user and self-configures to recognize desired activities. It reconfigures itself as the environment changes, and encompasses principles supporting autonomous operation in open-ended environments. OPPORTUNITY mainstreams ambient intelligence and improves user acceptance by relaxing constraints on body-worn sensor characteristics, and eases the deployment in real-world environments. We summarize key achievements of the project so far. The project outcomes are robust activity recognition systems. This may enable smarter activity-aware energy-management in buildings, and advanced activity-aware health assistants.\",\n \"Title: Ensemble creation and reconfiguration for activity recognition: An information theoretic approach.\\nYear: 2011\\n\\nAbstract: Advances in sensing, portable computing devices, and wireless communication has lead to an increase in the number and variety of sensing enabled devices (e. g. smartphones or sensing garments). Pervasive computing and activity recognition systems should be able to take advantage of these sensors, even if they are not always available or appear in runtime. These sensors can be integrated into an ensemble that fuse their information to obtain the final decision. There is therefore a need for mechanisms to select which sensors should compose the ensemble, as well as techniques for dynamically reconfigure the ensemble so as to integrate new sensors.Sensors can be integrated into an ensemble where information from each of them is fused to obtain the final decisions. From the machine learning point of view, this corresponds to the combination of classifiers where measures of the accuracy and diversity of the ensemble are used to select the elements that may lead to the highest performance. Recent works propose measures of accuracy and diversity based on an information theoretical approach. In this paper we study the use of these measures for selecting ensembles in activity recognition based on body sensor networks. Besides a comparison with traditional diversity measures (e. g., Q-, kappa-statistics), we also present mechanisms to exploit these measures for the dynamic reconfiguration of the ensemble and detection of changes in the network.\",\n \"Title: OPPORTUNITY: Towards opportunistic activity and context recognition systems\\nYear: 2009\\n\\nAbstract: Opportunistic sensing allows to efficiently collect infor- mation about the physical world and the persons behav- ing in it. This may mainstream human context and activ- ity recognition in wearable and pervasive computing by re- moving requirements for a specific deployed infrastructure. In this paper we introduce the newly started European re- search project OPPORTUNITY within which we develop mobile opportunistic activity and context recognition sys- tems. We outline the project's objective, the approach we follow along opportunistic sensing, data processing and in- terpretation, and autonomous adaptation and evolution to environmental and user changes, and we outline prelimi- nary results.\",\n \"Title: Person Authentication Using Brainwaves (EEG) and Maximum A Posteriori Model Adaptation\\nYear: 2007\\n\\nAbstract: In this paper, we investigate the use of brain activity for person authentication. It has been shown in previous studies that the brain-wave pattern of every individual is unique and that the electroencephalogram (EEG) can be used for biometric identification. EEG-based biometry is an emerging research topic and we believe that it may open new research directions and applications in the future. However, very little work has been done in this area and was focusing mainly on person identification but not on person authentication. Person authentication aims to accept or to reject a person claiming an identity, i.e., comparing a biometric data to one template, while the goal of person identification is to match the biometric data against all the records in a database. We propose the use of a statistical framework based on Gaussian Mixture Models and Maximum A Posteriori model adaptation, successfully applied to speaker and face authentication, which can deal with only one training session. We perform intensive experimental simulations using several strict train/test protocols to show the potential of our method. We also show that there are some mental tasks that are more appropriate for person authentication than others.\",\n \"Title: Interaction And Evaluation Of An Augmented Virtuality Assistance System For Teleoperated Robots\\nYear: 2012\\n\\nAbstract: This paper presents the main features and capabilities of a developed system based on augmented virtuality (AV), which is devoted to the assisted navigation of teleoperated robots. The goal is to provide users with a greater perception of the robot navigation environment that improves the accuracy in teleoperation tasks and reduces the workload required to drive. The developed system is a mixed-perspective exocentric display (ME3D) type. In order to assess the work carried out, a comparative study between the developed ME3D interface and a video-centric display (VC2D) has been conducted. To this end, we have implemented both interfaces on a real robot and performed an experiment with 16 subjects in a real scenario. As a result, we have obtained a high degree of acceptance in the use of the ME3D interface by participants.\",\n \"Title: REINFORCEMENT LEARNING OF GOAL-DIRECTED OBSTACLE-AVOIDING REACTION STRATEGIES IN AN AUTONOMOUS MOBILE ROBOT\\nYear: 1995\\n\\nAbstract: In this paper we argue for building reactive autonomous mobile robots through reinforcement connectionist learning. Nevertheless, basic reinforcement learning is a slow process. This paper describes an architecture which deals with complex-high-dimensional and/or continuous-situation and action spaces effectively. This architecture is based on two main ideas. The first is to organize the reactive component into a set of modules in such a way that, roughly, each one of them codifies the prototypical action for a given cluster of situations. The second idea is to use a particular kind of planning for figuring out what part of the action space deserves attention for each cluster of situations. Salient features of the planning process are that it is grounded and that it is invoked only when the reactive component does not generalize correctly its previous experience to the new situation. We also report our experience in solving a basic task that most autonomous mobile robots must face, namely path finding.\",\n \"Title: A Modular Reinforcement-Based Neural Controller For A Three-Link Manipulator\\nYear: 1997\\n\\nAbstract: This paper presents a modular neural controller that learns goal-oriented obstacle-avoiding motion strategies for a sensor-based three-link planar robot arm. It acquires these strategies through reinforcement learning from focal sensory data. The controller has two reinforcement-based modules: a module for negotiating obstacles and a module for moving to the goal. Both modules generate actions that are interpreted with regard to a goal vector in the robot joint space. A differential inverse kinematics (DIV) module is used to obtain such a goal vector. The DIV module is based on the inversion of a neural network that has been previously trained to approximate the manipulator forward kinematics in polar coordinates. The controller achieves a satisfactory performance quite rapidly and shows good generalization capabilities in the face of new environments.\",\n \"Title: A local neural classifier for the recognition of EEG patterns associated to mental tasks\\nYear: 2002\\n\\nAbstract: This paper proposes a novel and simple local neural classifier for the recognition of mental tasks from on-line spontaneous EEG signals. The proposed neural classifier recognizes three mental tasks from on-line spontaneous EEG signals. Correct recognition is around 70%. This modest rate is largely compensated by two properties, namely low percentage of wrong decisions (below 5%) and rapid responses (every 1/2 s). Interestingly, the neural classifier achieves this performance with a few units, normally just one per mental task. Also, since the subject and his/her personal interface learn simultaneously from each other, subjects master it rapidly (in a few days of moderate training). Finally, analysis of learned EEG patterns confirms that for a subject to operate satisfactorily a brain interface, the latter must fit the individual features of the former\",\n \"Title: Neural Approaches to Robot Control: Four Representative Applications\\nYear: 1995\\n\\nAbstract: This paper reviews neural network techniques for achieving adaptivity in both manipulator and mobile robots. It is structured in two parts. First, the different learning approaches are classified according to the amount of training information they require: quantitative (supervised approaches), qualitative (reinforcement-based approaches) and none (unsupervised approaches). Afterwards, the adequacy of each approach for solving specific problems in robot control is illustrated through four working industrial prototypes developed by the authors in the frame of two Esprit projects. The problems tackled are the inverse kinematics and inverse dynamics of robot manipulators, visual robot positioning and mobile robot navigation.\",\n \"Title: The Use of Brain-Computer Interfacing in Ambient Intelligence.\\nYear: 2007\\n\\nAbstract: This paper is aimed to introduce IDIAP Brain Computer Interface (IBCI) research that successfully applied Ambience Intelligence (And) principles in designing intelligent brain-machine interactions. We proceed through (IBCI) applications describing how machines call decode and react to the human mental commands, cognitive and emotive states. We show how effective human-machine interaction for brain computer interfacing (BCI) can be achieved through, 1) asynchronous and spontaneous BCI, 2) shared control between the human and machine, 3) online learning and 4) the use of cognitive state recognition. Identifying common principles in BCI research and ambiance intelligence (AmI) research, we discuss IBCI applications. With the current studies oil recognition of human cognitive states, we argue for the possibility of designing empathic environments or devices that, have a better human like understanding directly from brain signals.\",\n \"Title: The timing of exploratory decision-making revealed by single-trial topographic EEGanalyses.\\nYear: 2012\\n\\nAbstract: Decision-making in an uncertain environment is driven by two major needs: exploring the environment to gather information or exploiting acquired knowledge to maximize reward. The neural processes underlying exploratory decision-making have been mainly studied by means of functional magnetic resonance imaging, overlooking any information about the time when decisions are made. Here, we carried out an electroencephalography (EEG) experiment, in order to detect the time when the brain generators responsible for these decisions have been sufficiently activated to lead to the next decision. Our analyses, based on a classification scheme, extract time-unlocked voltage topographies during reward presentation and use them to predict the type of decisions made on the subsequent trial. Classification accuracy, measured as the area under the Receiver Operator's Characteristic curve was on average 0.65 across 7 subjects. Classification accuracy was above chance levels already after 516ms on average, across subjects. We speculate that decisions were already made before this critical period, as confirmed by a positive correlation with reaction times across subjects. On an individual subject basis, distributed source estimations were performed on the extracted topographies to statistically evaluate the neural correlates of decision-making. For trials leading to exploration, there was significantly higher activity in dorsolateral prefrontal cortex and the right supramarginal gyrus; areas responsible for modulating behavior under risk and deduction. No area was more active during exploitation. We show for the first time the temporal evolution of differential patterns of brain activation in an exploratory decision-making task on a single-trial basis.\",\n \"Title: Detecting and Rectifying Anomalies in Body Sensor Networks\\nYear: 2011\\n\\nAbstract: Activity recognition using on body sensors are prone to degradation due to changes on sensor readings. The changes can occur because of degradation or alteration in the behaviour of the sensor with respect to the others. In this paper we propose a method which detects anomalous nodes in the network and takes compensatory actions to keep the performance of the system as high as possible while the system is running. We show on two activity datasets with different configurations of on body sensors that detection and compensation of anomalies make the system more robust against the changes.\",\n \"Title: Bayesian Controller for a Novel Semi-Autonomous Navigation Concept.\\nYear: 2007\\n\\nAbstract: This paper presents a novel concept of semi- autonomous navigation where a mobile robot evolves au- tonomously under the monitoring of a human user. The user provides corrective commands to the robot whenever he disagrees with the robot's navigational choices. These commands are not related to navigational values like directions or goals, but to the relevance of the robot's actions to the overall task. A binary error signal is used to correct the robot's decisions and to bring it to the desired goal location. This simple interface could easily be adapted to input systems designed for disabled people, offering them a convenient alternative to existing assisti ve systems. After a description of the whole concept, a special focus is given to the decisional process, which takes into account in a Bayesian way the environment perceived by the robot and the user generated signals in order to propose a navigational strategy to the human user. The strength and advantages of the proposed semi-autonomous concept are illustrated with two experiments.\",\n \"Title: Fast recognition of anticipation-related potentials.\\nYear: 2009\\n\\nAbstract: Anticipation increases the efficiency of daily tasks by partial advance activation of neural substrates involved in it. Here, we develop a method for the recognition of EEG correlates of this activation as early as possible on single trials, which is essential for brain-computer interaction. We explore various features from the EEG recorded in a contingent negative variation (CNV) paradigm. We als...\",\n \"Title: Using Machine Learning Techniques in Real-World Mobile Robots\\nYear: 1995\\n\\nAbstract: Applying machine learning techniques can help mobile robots meet the need for increased safety and adaptivity that real-world operation demands. The techniques also facilitate robot-to-user communication.Mobile robots are gradually leaving the laboratories and entering the real world. They are employed in automated factories, used for plant supervision, and are increasingly successful in service tasks such as health care. Almost 100 hospitals in the US and Europe use TRC's HelpMate, for example. However, if mobile robots are to find wide use in the real world, they must be able to learn from their experience. They must also be more adaptive, communicative, and safe.To meet these challenges, the complexity of the robot's control software must increase dramatically. The loop between the robot's perceptions and its actions must narrow on several levels of abstraction. This hierarchy of increasingly abstract situation-action rules must be grounded: it must map directly to the robot's basic sensing and motion capabilities. Building these rules requires that the knowledge related to both the task and the robot be codified.In addition, the robot's task specification must be accessible to the average user. The robot must learn to transform its own perceptions and actions into the user's language, and to compile the user's task specification into a set of directly executable commands. The omnipresent problems of symbol grounding and signal-to-symbol transformation become even more challenging if the robot is adapting its behavior according to both user needs and environmental changes.This article shows how machine learning techniques can help us meet these challenges. Using these techniques, we built increasingly abstract representations of a robot's perceptions and actions. This produced a symbolic description of what the robot knows and can do. Because this task is fairly complex, we first identified those subproblems that a learning method can solve efficiently, and isolated those with good classical solutions. Also, for a robot to solve a complex problem, we had to find solutions for several learning tasks. We identified these learning tasks and the learning techniques appropriate for their solution. To evaluate our approach, we used the mobile robots Priamos and Teseo.\",\n \"Title: On the use of brain decoded signals for online user adaptive gesture recognition systems\\nYear: 2010\\n\\nAbstract: Activity and context recognition in pervasive and wearable computing ought to continuously adapt to changes typical of open-ended scenarios, such as changing users, sensor characteristics, user expectations, or user motor patterns due to learning or aging. System performance inherently relates to the user's perception of the system behavior. Thus, the user should be guiding the adaptation process. This should be automatic, transparent, and unconscious. We capitalize on advances in electroencephalography (EEG) signal processing that allow for error related potentials (ErrP) recognition. ErrP are emitted when a human observes an unexpected behavior in a system. We propose and evaluate a hand gesture recognition system from wearable motion sensors that adapts online by taking advantage of ErrP. Thus the gesture recognition system becomes self-aware of its performance, and can self-improve through re-occurring detection of ErrP signals. Results show that our adaptation technique can improve the accuracy of a user independent gesture recognition system by 13.9% when ErrP recognition is perfect. When ErrP recognition errors are factored in, recognition accuracy increases by 4.9%. We characterize the boundary conditions of ErrP recognition guaranteeing beneficial adaptation. The adaptive algorithms are applicable to other forms of activity recognition, and can also use explicit user feedback rather than ErrP.\",\n \"Title: Error-Related EEG Potentials Generated During Simulated Brain-Computer Interaction.\\nYear: 2008\\n\\nAbstract: Brain-computer interfaces (BCIs) are prone to errors in the recognition of subject's intent. An elegant approach to improve the accuracy of BCIs consists in a verification procedure directly based on the presence of error-related potentials (ErrP) in the electroencephalogram (EEG) recorded right after the occurrence of an error. Several studies show the presence of ErrP in typical choice reaction ...\",\n \"Title: Real-time prediction of fast and slow delivery of mental commands in a motor imagery BCI: An entropy-based approach\\nYear: 2012\\n\\nAbstract: Providing adaptive shared control for Brain-Computer Interfaces (BCIs) can result in better performance while reducing the user's mental workload. In this respect, online estimation of accuracy and speed of command delivery are important factors. This study aims at real-time differentiation between fast and slow trials in a motor imagery BCI. In our experiments, we refer to trials shorter than the median of trial lengths as “fast” trials and to those longer than the median as “slow” trials. We propose a classifier for real-time distinction between fast and slow trials based on estimates of the entropy rates for the first 2-3 s of the electroencephalogram (EEG). Results suggest that it can be predicted whether a trial is slow or fast well before a cutoff time. This is important for adaptive shared control especially because 55% to 75% of trials (for the five subjects in this study) are longer than that cutoff time.\",\n \"Title: Robust activity recognition combining anomaly detection and classifier retraining.\\nYear: 2013\\n\\nAbstract: Activity recognition systems based on body-worn motion sensors suffer from a decrease in performance during the deployment and run-time phases, because of probable changes in the sensors (e.g. displacement or rotatation), which is the case in many real-life scenarios (e.g. mobile phone in a pocket). Existing approaches to achieve robustness tend to sacrifice information (e.g. by rotation-invariant features) or reduce the weight of the anomalous sensors at the classifier fusion stage (adaptive fusion), ignoring data which might still be perfectly meaningful, although different from the training data. We propose to use adaptation to rebuild the classifier models of the sensors which have changed position by a two-step approach: in the first step, we run an anomaly detection algorithm to automatically detect which sensors are delivering unexpected data; subsequently, we trigger a system self-training process, so that the remaining classifiers retrain the “anomalous” sensors. We show the benefit of this approach in a real activity recognition dataset comprising data from 8 sensors to recognize locomotion. The approach achieves similar accuracy compared to the upper baseline, obtained by retraining the anomalous classifiers on the new data.\",\n \"Title: Robot arm reaching through neural inversions and reinforcement learning\\nYear: 2000\\n\\nAbstract: We present a neural method that computes the inverse kinematics of any kind of robot manipulators; both redundant and non-redundant. Inverse kinematics solutions are obtained through the inversion of a neural network that has been previously trained to approximate the manipulator forward kinematics. The inversion provides difference vectors in the joint space from difference vectors in the workspace. Our differential inverse kinematics (DIV) approach can be viewed as a neural network implementation of the Jacobian transpose method for arm kinematic control that does not require previous knowledge of the arm forward kinematics. Redundancy can be exploited to obtain a special inverse kinematic solution that meets a particular constraint (e.g. joint limit avoidance) by inverting an additional neural network The usefulness of our DIV approach is further illustrated with sensor-based multilink manipulators that learn collision-free reaching motions in unknown environments. For this task, the neural controller has two modules: a reinforcement-based action generator (AG) and a DIV module that computes goal vectors in the joint space. The actions given by the AG are interpreted with regard to those goal vectors. (C) 2000 Published by Elsevier Science B.V. All rights reserved.\",\n \"Title: Learning and Stabilization of Altruistic Behaviors in Multi-Agent System\\nYear: 1997\\n\\nAbstract: Optimization of performance in collective systems often requires altruism. Emergence and stabilization of altruistic behaviors are difficult because the agents incur a cost when behaving altruistically. In this paper we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. Our multi-agent system is made up of autonomous agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learn stable altruistic behaviors, so reaching optimal (or near-to-optimal) performances in unknown and changing environments.\",\n \"Title: Brain-Computer Interfacing for Intelligent Systems\\nYear: 2008\\n\\nAbstract: Advances in cognitive neuroscience and brain-imaging technologies give us the unprecedented ability to interface directly with brain activity. These technologies let us monitor physical processes in the brain that correspond with certain forms of thought. Researchers have begun using these technologies to build brain-computer interfaces (BCIs)—communication systems that don't depend on the brain's normal output pathways of peripheral nerves and muscles. Four short articles provide a quick overview of the past, present, and future of BCIs.\",\n \"Title: Brain---computer interfaces for space applications\\nYear: 2011\\n\\nAbstract: Recent experiments have shown the possibility to use the brain electrical activity to directly control the movement of robots. Such a kind of brain---computer interface is a natural way to augment human capabilities by providing a new interaction link with the outside world and is particularly relevant as an aid for paralysed humans, although it also opens up new possibilities in human---robot interaction for able-bodied people. One of these new fields of application is the use of brain---computer interfaces in the space environment, where astronauts are subject to extreme conditions and could greatly benefit from direct mental teleoperation of external semi-automatic manipulators--for instance, mental commands could be sent without any output/latency delays, as it is the case for manual control in microgravity conditions. Previous studies show that there is a considerable potential for this technology onboard spacecraft.\",\n \"Title: Brain-coupled interaction for semi-autonomous navigation of an assistive robot\\nYear: 2010\\n\\nAbstract: This paper presents a novel semi-autonomous navigation strategy designed for low throughput interfaces. A mobile robot (e.g. intelligent wheelchair) proposes the most probable action, as analyzed from the environment, to a human user who can either accept or reject the proposition. In the case of refusal, the robot will propose another action, until both entities agree on what needs to be done. In an unknown environment, the robotic system first extracts features so as to recognize places of interest where a human-robot interaction should take place (e.g. crossings). Based on the local topology, relevant actions are then proposed, the user providing answers by means of a button or a brain-computer interface (BCI). Our navigation strategy is successfully tested both in simulation and with a real robot, and a feasibility study for the use of a BCI confirms the potential of such an interface.\",\n \"Title: Temporal Processing of Brain Activity for the Recognition of EEG Patterns\\nYear: 2002\\n\\nAbstract: This paper discusses three common strategies to incorporate temporal dynamics of brain activity to recognize 3 mental tasks from spontaneous EEG signals. The networks have been tested in a hard experimental setup; namely, generalization over different recording sessions while analyzing short time windows. It turns out that the simple local neural classifier currently embedded in our BCI, which averages the response to 8 consecutive EEG samples, is to be preferred to more complex time-processing networks such as TDNN and Elman-like. With this local classifier, users with some hours of training are able to operate several brain-actuated applications.\",\n \"Title: Non-invasive brain-actuated control of a mobile robot\\nYear: 2003\\n\\nAbstract: Recent experiments have indicated the possibility to use the brain electrical activity to directly control the movement of robotics or prosthetic devices. In this paper we report results with a portable non-invasive brain-computer interface that makes possible the continuous control of a mobile robot in a house-like environment. The interface uses 8 surface electrodes to measure electroencephalogram (EEG) signals from which a statistical classifier recognizes 3 different mental states. Until now, brain-actuated control of robots has relied on invasive approaches-requiring surgical implantation of electrodes-since EEG-based systems have been considered too slow for controlling rapid and complex sequences of movements. Here we show that, after a few days of training, two human subjects successfully moved a robot between several rooms by mental control only. Furthermore, mental control was only marginally worse than manual control on the same task.\",\n \"Title: Neural Network Learning of Variable Grid-Based Maps for the Autonomous Navigation of Robots\\nYear: 1997\\n\\nAbstract: This paper presents a map learning method that integrates the geometrical and topological paradigms. The geometrical component consists of a feed-forward neural network that interprets the robot's sensor readings efficiently. The topological map is created by learning a variable resolution partitioning of the world. Every partition corresponds to a perceptually homogeneous region. The efficiency of the learning process is based on the use of local memory-based techniques for partitioning and of active learning techniques for selecting the most appropriate region to be explored next. Finally, the paper reports experimental results obtained with the autonomous mobile robot TESEO.\",\n \"Title: A comparative psychophysical and EEG study of different feedback modalities for HRI\\nYear: 2008\\n\\nAbstract: This paper presents a comparison between six different ways to convey navigational information provided by a robot to a human. Visual, auditory, and tactile feedback modalities were selected and designed to suggest a direction of travel to a human user, who can then decide if he agrees or not with the robot's proposition. This work builds upon a previous research on a novel semi-autonomous navigation system in which the human supervises an autonomous system, providing corrective monitoring signals whenever necessary. We recorded both qualitative (user impressions based on selected criteria and ranking of their feelings) and quantitative (response time and accuracy) information regarding different types of feedback. In addition, a preliminary analysis of the influence of the different types of feedback on brain activity is also shown. The result of this study may provide guidelines for the design of such a human-robot interaction system, depending on both the task and the human user.\",\n \"Title: Quantifying electrode reliability during brain-computer interface operation.\\nYear: 2015\\n\\nAbstract: One of the problems of noninvasive brain-computer interface (BCI) applications is the occurrence of anomalous (unexpected) signals that might degrade BCI performance. This situation might slip the operator's attention since raw signals are not usually continuously visualized and monitored during BCI-actuated device operation. Anomalous data can for instance be the result of electrode misplacement, degrading impedance or loss of connectivity. Since this problem can develop at run time, there is a need of a systematic approach to evaluate electrode reliability during online BCI operation. In this paper, we propose two metrics detecting how much each channel is deviating from its expected behavior. This quantifies electrode reliability at run time which could be embedded into BCI data processing to increase performance. We assess the effectiveness of these metrics in quantifying signal degradation by conducting three experiments: Electrode swap, electrode manipulation, and offline artificially degradation of P300 signals.\",\n \"Title: Prediction of command delivery time for BCI\\nYear: 2014\\n\\nAbstract: One of the challenges in using brain computer interfaces over extended periods of time is the uncertainty in the system. This uncertainty can be due to the user's internal states, the non stationarity of the brain signals, or the variation of the class discriminative information over time. Therefore, the users are often unable to maintain the same accuracy and time efficiency in delivering BCI commands. In this paper, we tackle the issue of variation in BCI command delivery time for a motor imagery task with the aim of providing assistance through adaptive shared control. This is important mainly because having long delivery of mental commands leads to uncertainty in the user's intent classification and limits the responsiveness of the system. In order to address this issue, we separate the trials into long and short groups so that we have the same number of trials in each group. We demonstrate that using only a few samples at the beginning of the trial, we are able to predict whether the current trial will be short or long with high accuracies (70% - 86%). Eventually, this prediction enables us to tune the shared control parameters to overcome the issue of uncertainty.\",\n \"Title: EEG correlates of active visual search during simulated driving: An exploratory study\\nYear: 2014\\n\\nAbstract: Brain responses to visual stimuli can provide information about visual recognition processes. Several studies have shown stimulus-dependent modulation of the evoked neural responses after gaze shifts (i.e. eye fixation related potentials, EFRP) depending on the relevance of the fixated object. However these studies are typically performed on still images under constrained conditions. Here we extend this approach to study overt visual attention during a simulated driving task. Simultaneous analysis of eye-tracking and electroencephalography data revealed similar patterns than those previously reported. However, natural visual exploration yielded shorter fixations, which imposes constraints in the analysis of the elicited brain responses. Nevertheless, we found significant differences between EFRPs corresponding to target objects or non-object stimuli. These results suggest the possibility of decoding such information during driving, allowing better understanding of how drivers process the environmental information.\",\n \"Title: Quantification and reduction of visual load during BCI operation\\nYear: 2014\\n\\nAbstract: Operating a brain-actuated vehicle in real-world environments requires much of our visual attention. However, a typical brain-computer interface (BCI) sends the feedback information about the current status of the user's brain also via the visual channel. As a result, users have to split their visual attention into two: one for the surroundings and the other for the visual BCI feedback. Therefore, we recently developed a tactile stimulation system that successfully replaced the conventional visual feedback. Here we employ the multiple object tracking experiments to quantify the visual load added by the visual feedback. The result show that the additional visual load is almost eliminated, and the true negative rate of the BCI operation (intentional non-control) is improved when the visual feedback is replaced by the tactile feedback.\",\n \"Title: Subject-oriented training for motor imagery brain-computer interfaces.\\nYear: 2014\\n\\nAbstract: Successful operation of motor imagery (MI)-based brain-computer interfaces (BCI) requires mutual adaptation between the human subject and the BCI. Traditional training methods, as well as more recent ones based on co-adaptation, have mainly focused on the machine-learning aspects of BCI training. This work presents a novel co-adaptive training protocol shifting the focus on subject-related performances and the optimal accommodation of the interactions between the two learning agents of the BCI loop. Preliminary results with 8 able-bodied individuals demonstrate that the proposed method has been able to bring 3 naive users into control of a MI BCI within a few runs and to improve the BCI performances of 3 experienced BCI users by an average of 0.36 bits/sec.\",\n \"Title: Phase-based features for motor imagery brain-computer interfaces.\\nYear: 2011\\n\\nAbstract: Motor imagery (MI) brain-computer interfaces (BCIs) translate a subject's motor intention to a command signal. Most MI BCIs use power features in the mu or beta rhythms, while several results have been reported using a measure of phase synchrony, the phase-locking value (PLV). In this study, we investigated the performance of various phase-based features, including instantaneous phase difference (IPD) and PLV, for control of a MI BCI. Patterns of phase synchrony differentially appear over the motor cortices and between the primary motor cortex (M1) and supplementary motor area (SMA) during MI. Offline results, along with preliminary online sessions, indicate that IPD serves as a robust control signal for differentiating between MI classes, and that the phase relations between channels are relatively stable over several months. Offline and online trial-level classification accuracies based on IPD ranged from 84% to 99%, whereas the performance for the corresponding amplitude features ranged from 70% to 100%.\",\n \"Title: Brain-controlled telepresence robot by motor-disabled people.\\nYear: 2011\\n\\nAbstract: In this paper we present the first results of users with disabilities in mentally controlling a telepresence robot, a rather complex task as the robot is continuously moving and the user must control it for a long period of time (over 6 minutes) to go along the whole path. These two users drove the telepresence robot from their clinic more than 100 km away. Remarkably, although the patients had never visited the location where the telepresence robot was operating, they achieve similar performances to a group of four healthy users who were familiar with the environment. In particular, the experimental results reported in this paper demonstrate the benefits of shared control for brain-controlled telepresence robots. It allows all subjects (including novel BMI subjects as our users with disabilities) to complete a complex task in similar time and with similar number of commands to those required by manual control.\",\n \"Title: Online modulation of the level of assistance in shared control systems\\nYear: 2012\\n\\nAbstract: In this paper we propose a method to modulate the level of assistance provided by a shared controller, not only given the environmental context, but also according to the context of the user's current behaviour. We show that the enhanced situational context can be adequately captured by using online performance metrics (such as those more usually found in the evaluation of shared control systems). The resultant controller not only allows the user to perform better in the primary task (like many shared control systems), but has also has increased the level of user acceptance, due to the personalised dynamics of the control policy.\",\n \"Title: The birth of the brain-controlled wheelchair\\nYear: 2012\\n\\nAbstract: The prospect of controlling devices merely by the power of one's thoughts is compelling, especially for assistive technology applications. In the accompanying video, we show how we have strived to push brain-computer interface (BCI) technology out of the lab and into the real world, while simultaneously moving away from testing solely with healthy subjects to undertaking trials with patients and potential end-users. We describe the evolution of the motor imagery based BCI, which has resulted in a major milestone: the first patient trial of a motor imagery based BCI controlled wheelchair.\",\n \"Title: Brain-Controlled Wheelchairs: A Robotic Architecture\\nYear: 2013\\n\\nAbstract: Independent mobility is central to being able to perform activities of daily living by oneself. However, power wheelchairs are not an option for many people who, due to severe motor disabilities, are unable to use conventional controls. For some of these people, noninvasive brain-computer interfaces (BCIs) offer a promising solution to this interaction problem.\",\n \"Title: Freeing the visual channel by exploiting vibrotactile BCI feedback.\\nYear: 2013\\n\\nAbstract: Controlling a brain-actuated device requires the participant to look at and to split his attention between the interaction of the device with its environment and the status information of the Brain-Computer Interface (BCI). Such parallel visual tasks are partly contradictory, with the goal of achieving a good and natural device control. Is there a possibility to free the visual channel from one of these tasks? To address this, a stimulation system based on 6 coin-motors is developed, which provides a spatially continuous tactile illusion as BCI feedback, so that the visual channel can be devoted to the device. Several experiments are conducted in this work, to optimize the tactile illusion patterns and to investigate the influence on the electroencephalogram (EEG). Finally, 6 healthy BCI participants compare visual with tactile feedback in online BCI recordings. The developed stimulator can be used without interfering with the EEG. All subjects are able to perceive this type of tactile feedback well, and no statistical degradation in the online BCI performance could be identified between visual and tactile feedback.\",\n \"Title: A hybrid BCI for enhanced control of a telepresence robot.\\nYear: 2013\\n\\nAbstract: Motor-disabled end users have successfully driven a telepresence robot in a complex environment using a Brain-Computer Interface (BCI). However, to facilitate the interaction aspect that underpins the notion of telepresence, users must be able to voluntarily and reliably stop the robot at any moment, not just drive from point to point. In this work, we propose to exploit the user's residual muscular activity to provide a fast and reliable control channel, which can start/stop the telepresence robot at any moment. Our preliminary results show that not only does this hybrid approach increase the accuracy, but it also helps to reduce the workload and was the preferred control paradigm of all the participants.\",\n \"Title: Offline decoding of upper limb muscle synergies from EEG slow cortical potentials.\\nYear: 2013\\n\\nAbstract: Muscle synergies are thought to be the building blocks used by the central nervous system to control the underdetermined problem of muscles activation. Decoding these synergies from EEG could provide useful tools for BCI-controlled orthotic devices. In this paper, we assess the possibility of decoding muscle synergies from EEG slow cortical potentials in two healthy subjects and two stroke patients performing a center-out reaching task. We were able to successfully decode the extracted muscle synergies in both healthy subject and one patient.\",\n \"Title: Steering timing prediction in a driving simulator task.\\nYear: 2013\\n\\nAbstract: In this paper we present the preliminary results of a pioneering attempt to predict the timing of steering actions in a driving task from non-invasive EEG measurements. The experiment took place with the subjects driving a car at a constant speed on a simulated highway in a driving simulator. The EEG activity was analyzed during periods of straight driving and during lane change actions. Classifiers were built on the signals recorded over the motor areas for straight and pre-steering periods. The onset of the steering actions was detected on average 811 ms before the action with a 74.6% true positive rate.\",\n \"Title: Towards Noninvasive Hybrid Brain–Computer Interfaces: Framework, Practice, Clinical Application, and Beyond\\nYear: 2015\\n\\nAbstract: In their early days, brain-computer interfaces (BCIs) were only considered as control channel for end users with severe motor impairments such as people in the locked-in state. But, thanks to the multidisciplinary progress achieved over the last decade, the range of BCI applications has been substantially enlarged. Indeed, today BCI technology cannot only translate brain signals directly into control signals, but also can combine such kind of artificial output with a natural muscle-based output. Thus, the integration of multiple biological signals for real-time interaction holds the promise to enhance a much larger population than originally thought end users with preserved residual functions who could benefit from new generations of assistive technologies. A BCI system that combines a BCI with other physiological or technical signals is known as hybrid BCI (hBCI). In this work, we review the work of a large scale integrated project funded by the European commission which was dedicated to develop practical hybrid BCIs and introduce them in various fields of applications. This article presents an hBCI framework, which was used in studies with nonimpaired as well as end users with motor impairments.\",\n \"Title: Very high frequency oscillations (VHFO) as a predictor of movement intentions.\\nYear: 2006\\n\\nAbstract: Gamma band (30–80 Hz) oscillations arising in neuronal ensembles are thought to be a crucial component of the neural code. Recent studies in animals suggest a similar functional role for very high frequency oscillations (VHFO) in the range 80–200 Hz. Since some intracerebral studies in humans link VHFO to epileptogenesis, it remains unclear if VHFO appear in the healthy human brain and if so which is their role. This study uses EEG recordings from twelve healthy volunteers, engaged in a visuo-motor reaction time task, to show that VHFO are not necessarily pathological but rather code information about upcoming movements. Oscillations within the range (30–200 Hz) occurring in the period between stimuli presentation and the fastest hand responses allow highly accurate (>96%) prediction of the laterality of the responding hand in single trials. Our results suggest that VHFO belong in functional terms to the gamma band that must be considerably enlarged to better understand the role of oscillatory activity in brain functioning. This study has therefore important implications for the recording and analysis of electrophysiological data in normal subjects and patients.\",\n \"Title: Detection Of Anticipatory Brain Potentials During Car Driving\\nYear: 2012\\n\\nAbstract: Recognition of driver's intention from electroencephalogram (EEG) can be helpful in developing an in-car brain computer interface (BCI) systems for intelligent cars. This could be beneficial in enhancing the quality of interaction between the driver and the car to provide the response of the intelligent cars in line with driver's intention. We proposed investigating anticipation as the cognitive state leading to specific actions during car driving. An experimental protocol is designed for recording EEG from 6 subjects while driving the virtual reality driving simulator. The experimental protocol is a variant of the contingent negative variation (CNV) paradigm with Go and No-go conditions in driving framework. The results presented in this study support the presence of the slow cortical anticipatory potentials in EEG grand averages and also confirm the discriminability of these potentials in offline single trial classification with the average of 0.76 +/- 0.12 in area under the curve (AUC).\",\n \"Title: Anticipation- And Error-Related Eeg Signals During Realistic Human-Machine Interaction: A Study On Visual And Tactile Feedback\\nYear: 2012\\n\\nAbstract: The exploitation of EEG signatures of cognitive processes can provide valuable information to improve interaction with brain actuated devices. In this work we study these correlates in a realistic situation simulated in a virtual reality environment. We focus on cortical potentials linked to the anticipation of future events (i.e. the contingent negative variation, CNV) and error-related potentials elicited by both visual and tactile feedback. Experiments with 6 subjects show brain activity consistent with previous studies using simpler stimuli, both at the level of ERPs and single trial classification. Moreover, we observe comparable signals irrespective of whether the subject was required to perform motor actions. Altogether, these results support the possibility of using these signals for practical brain machine interaction.\",\n \"Title: Improved Recognition Of Error Related Potentials Through The Use Of Brain Connectivity Features\\nYear: 2012\\n\\nAbstract: Brain error processing plays a key role in goal-directed behavior and learning in human brain. Directed transfer function (DTF) on EEG signal brings unique features for discrimination between correct and error cases in brain-computer interface (BCI) system. We describe the first application of brain connectivity features for recognizing error-related signals in non-invasive BCI. EEG signal were recorded from 16 human subjects when they monitored stimuli moving in either correct or erroneous direction. Classification performance using waveform features, brain connectivity features and their combination were compared. The result of combined features yielded highest classification accuracy, 0.85. In addition, we also show that brain connectivity at theta band around 200ms after stimuli carry highly discriminant information between error and correct trials. This paper provides evidence that the use of connectivity features improve the performance of an EEG based BCI.\",\n \"Title: Adaptive Assistance for Brain-Computer Interfaces by Online Prediction of Command Reliability\\nYear: 2016\\n\\nAbstract: Abstract-One of the challenges of using brain-computer interfaces (BCIs) over extended periods of time is the variation of the users' performance from one experimental day to another. The goal of the current study is to propose a performance estimator for an electroencephalography-based motor imagery BCI by assessing the reliability of a command (i.e., predicting a 'short' or 'long' command delivery time, CDT). Using a short time window (<1.5 s, shorter than the delivery time) of the mental task execution and a linear discriminant analysis classifier, we could reliably differentiate between short and long CDT (Area under the sensitivity-specificity curve, AUC . 0.8) for 9 healthy subjects. Moreover, we assessed the feasibility of providing online adaptive assistance using the performance estimator in a BCI game by comparing two conditions: (i) allowing a 'fixed timeout' to deliver each command or (ii) providing 'adaptive assistance' by giving more time if the performance estimator detects a long CDT. The results revealed that providing adaptive assistance increases the ratio of correct commands significantly cantly (p <0.01). Moreover, the task load index (measured via the NASA TLX questionnaire) shows a significantly higher user acceptance in case of providing adaptive assistance (p <0.01). Furthermore, the results obtained in this study were used to simulate a robotic navigation scenario, which showed how adaptive assistance improved performance.\",\n \"Title: Context-based filtering for assisted brain-actuated wheelchair driving\\nYear: 2007\\n\\nAbstract: Controlling a robotic device by using human brain signals is an interesting and challenging task. The device may be complicated to control and the nonstationary nature of the brain signals provides for a rather unstable input. With the use of intelligent processing algorithms adapted to the task at hand, however, the performance can be increased. This paper introduces a shared control system that helps the subject in driving an intelligent wheelchair with a noninvasive brain interface. The subject's steering intentions are estimated from electroencephalogram (EEG) signals and passed through to the shared control system before being sent to the wheelchair motors. Experimental results show a possibility for significant improvement in the overall driving performance when using the shared control system compared to driving without it. These results have been obtained with 2 healthy subjects during their first day of training with the brain-actuated wheelchair.\",\n \"Title: Discriminant brain connectivity patterns of performance monitoring at average and single-trial levels.\\nYear: 2015\\n\\nAbstract: Electrophysiological and neuroimaging evidence suggest the existence of common mechanisms for monitoring erroneous events, independent of the source of errors. Previous works have described modulations of theta activity in the medial frontal cortex elicited by either self-generated errors or erroneous feedback. In turn, similar patterns have recently been reported to appear after the observation of external errors. We report cross-regional interactions after observation of errors at both average and single-trial levels. We recorded scalp electroencephalography (EEG) signals from 15 subjects while monitoring the movement of a cursor on a computer screen. Connectivity patterns, estimated using multivariate auto-regressive models, show increased error-related modulations of the information transfer in the theta and alpha bands between frontocentral and frontolateral areas. Conversely, a decrease of connectivity in the beta band is also observed. These network patterns are similar to those elicited by self-generated errors. However, since no motor response is required, they appear to be related to intrinsic mechanisms of error processing, instead of being linked to co-activation of motor areas. Noticeably, we demonstrate that cross-regional interaction patterns can be estimated on a trial-by-trial basis. These trial-specific patterns, consistent with the multi-trial analysis, convey discriminant information on whether a trial was elicited by observation of an erroneous action. Overall, our study supports the role of frequency-specific modulations in the medial frontal cortex in coordinating cross-regional activity during cognitive monitoring at a single-trial basis.\",\n \"Title: Towards Independence: A BCI Telepresence Robot for People With Severe Motor Disabilities\\nYear: 2015\\n\\nAbstract: This paper presents an important step forward towards increasing the independence of people with severe motor disabilities, by using brain-computer interfaces to harness the power of the Internet of Things. We analyze the stability of brain signals as end-users with motor disabilities progress from performing simple standard on-screen training tasks to interacting with real devices in the real world. Furthermore, we demonstrate how the concept of shared control-which interprets the user's commands in context-empowers users to perform rather complex tasks without a high workload. We present the results of nine end-users with motor disabilities who were able to complete navigation tasks with a telepresence robot successfully in a remote environment (in some cases in a different country) that they had never previously visited. Moreover, these end-users achieved similar levels of performance to a control group of 10 healthy users who were already familiar with the environment.\",\n \"Title: Making The Most Of Context-Awareness In Brain-Computer Interfaces\\nYear: 2013\\n\\nAbstract: In order for brain-computer interfaces (BCIs) to be used reliably for extended periods of time, they must be able to adapt to the users evolving needs. This adaptation should not only be a function of the environmental (external) context, but should also consider the internal context, such as cognitive states and brain signal reliability. In this work, we propose three different shared control frameworks that have been used for BCI applications: contextual fusion, contextual gating, and contextual regulation. We review recently published results in the light of these three context-awareness frameworks. Then, we discuss important issues to consider when designing a shared controller for BCI.\",\n \"Title: Brain Correlates Of Lane Changing Reaction Time In Simulated Driving\\nYear: 2015\\n\\nAbstract: Psychophysical studies have reported correlation between neural activity in frontal and parietal areas and subject's reaction time in simple tasks. Here we study whether similar correlates can also be identified in driver's electroencephalography (EEG) activity when they perform steering actions triggered by exogenous stimuli (e.g. obstacles along the road). We report analysis of the EEG signals of fifteen subjects while they drive in a realistic car simulator. We found that the peak latency of the event-related potentials in frontal and parietal areas significantly correlates with the onset of the steering behavior. Similarly, modulations of the power in the theta band (4-8 Hz) prior to the action also correlates with the reaction times. These results provide evidence of reliable neural markers of the driver's response variability.\",\n \"Title: Stream fusion for multi-stream automatic speech recognition.\\nYear: 2016\\n\\nAbstract: Multi-stream automatic speech recognition (MS-ASR) has been confirmed to boost the recognition performance in noisy conditions. In this system, the generation and the fusion of the streams are the essential parts and need to be designed in such a way to reduce the effect of noise on the final decision. This paper shows how to improve the performance of the MS-ASR by targeting two questions; (1) How many streams are to be combined, and (2) how to combine them. First, we propose a novel approach based on stream reliability to select the number of streams to be fused. Second, a fusion method based on Parallel Hidden Markov Models is introduced. Applying the method on two datasets (TIMIT and RATS) with different noises, we show an improvement of MS-ASR.\",\n \"Title: Spatial filters yield stable features for error-related potentials across conditions\\nYear: 2016\\n\\nAbstract: Error-related potentials (ErrP) have been increasingly studied in psychophysical experiments as well as for brain-machine interfacing. In the latter case, the generalisation capabilities of ErrP decoders is a crucial element to avoid frequent recalibration processes, thus increasing their usability. Previous studies have suggested that ErrP signals are rather stable across recording sessions. Also, studies using protocols of serial stimuli presentation show that these potentials do not change significantly with the presentation rate. Here we complement these studies by analysing the decoding generalisation capabilities. Using data from monitoring experiments, we evaluate how much the performance degrades when tested in a condition different than the one the decoder was trained with. Moreover, we compare different spatial filtering techniques to see which preprocessing steps yield less-sensitive features for ErrP decoding.\",\n \"Title: Evaluating decoding performance of upper limb imagined trajectories during center-out reaching tasks\\nYear: 2016\\n\\nAbstract: In recent years, several studies have shown that there is a correlation between electroencephalographic (EEG) signals and hand-reaching kinematic parameters after applying linear decoders. These studies have been generally conducted using actual upper limb movements, but so far there has been little discussion about the possibility of applying these decoders to motor imagery tasks. Moreover, the use of these decoders is rather controversial and there is no general agreement about the metrics used to compare decoded and real kinematics. In this paper, we have applied this methodology to upper limb imagined movements using a center-out protocol. Our results show that, although decoding performance is poor, there are significant components, particularly in horizontal imagined movements, that could be translated into reliable output commands. For this purpose, we have proposed a discrete classification of reached targets showing significant classification rates when the number of classified targets decreases.\",\n \"Title: Superposition Model For Steady State Visually Evoked Potentials\\nYear: 2016\\n\\nAbstract: Steady State Visually Evoked Potentials (SSVEP) are signals produced in the occipital part of the brain when someone gaze a light flickering at a fixed frequency. These signals have been used for Brain Machine Interfacing (BMI), where one or more stimuli are presented and the system has to detect what is the stimulus the user is attending to. It has been proposed that the SSVEP signal is produced by superposition of Visually Evoked Potentials (VEP) but there is not a model that shows that. We propose a model for a SSVEP signal that is a superposition of the response due to the rising and falling edges of the stimulus and that can be calculated for different frequencies.We fixed the model for 4 subjects that gazed stimuli in the frequencies of 9Hz, 11Hz, 13Hz and 15Hz, and duty-cycles of 20%, 35%, 50%, 65%, and 80%. Since the phases of SSVEP signals are stable over the time, these were used to fix the model, without the amplitude; however, signals of scattered phases were discarded. The model parameters were found using the Oz electrode signals and a genetic algorithm.The mean absolute error (MAE) between the measured phase and the obtained one was calculated for each subject (named S1, S2, S3, and S4). The model was fixed for the subjects in the fundamental frequencies, just two of them in the second harmonic, and one in the third harmonic. We obtained a maximum MAE for 3 subjects (S1, S2, and S4) in the fundamental frequencies at 0.30 rad and one of them (S2) with 0.21 rad in the second harmonic. The last one (S3) signals show poor results with a MAE between 0.46 rad and 1.79 rad by including fundamental frequencies, and second and third harmonics. The results show similarities among the different model parameters such that it suggests that a general model could be obtained.\",\n \"Title: A brain-controlled exoskeleton with cascaded event-related desynchronization classifiers.\\nYear: 2017\\n\\nAbstract: This paper describes a brainmachine interface for the online control of a powered lower-limb exoskeleton based on electroencephalogram (EEG) signals recorded over the users sensorimotor cortical areas. We train a binary decoder that can distinguish two different mental states, which is applied in a cascaded manner to efficiently control the exoskeleton in three different directions: walk front, turn left and turn right. This is realized by first classifying the users intention to walk front or change the direction. If the user decides to change the direction, a subsequent classification is performed to decide turn left or right. The users mental command is conditionally executed considering the possibility of obstacle collision. All five subjects were able to successfully complete the 3-way navigation task using brain signals while mounted in the exoskeleton. We observed on average 10.2% decrease in overall task completion time compared to the baseline protocol.\",\n \"Title: Plug&Play Brain-Computer Interfaces for effective Active and Assisted Living control.\\nYear: 2017\\n\\nAbstract: Brain-Computer Interfaces (BCI) rely on the interpretation of brain activity to provide people with disabilities with an alternative/augmentative interaction path. In light of this, BCI could be considered as enabling technology in many fields, including Active and Assisted Living (AAL) systems control. Interaction barriers could be removed indeed, enabling user with severe motor impairments to gain control over a wide range of AAL features. In this paper, a cost-effective BCI solution, targeted (but not limited) to AAL system control is presented. A custom hardware module is briefly reviewed, while signal processing techniques are covered in more depth. Steady-state visual evoked potentials (SSVEP) are exploited in this work as operating BCI protocol. In contrast with most common SSVEP-BCI approaches, we propose the definition of a prediction confidence indicator, which is shown to improve overall classification accuracy. The confidence indicator is derived without any subject-specific approach and is stable across users: it can thus be defined once and then shared between different persons. This allows some kind of Plug&Play interaction. Furthermore, by modelling rest/idle periods with the confidence indicator, it is possible to detect active control periods and separate them from \\\"background activity\\\": this is capital for real-time, self-paced operation. Finally, the indicator also allows to dynamically choose the most appropriate observation window length, improving system's responsiveness and user's comfort. Good results are achieved under such operating conditions, achieving, for instance, a false positive rate of 0.16 min, which outperform current literature findings.\",\n \"Title: mano: A Wearable Hand Exoskeleton for Activities of Daily Living and Neurorehabilitation.\\nYear: 2018\\n\\nAbstract: Hand sensorimotor impairments are among the most common consequences of injuries affecting the central and peripheral nervous systems, leading to a drastic reduction in the quality of life for affected individuals. Combining wearable robotic exoskeletons and human-machine interfaces is a promising avenue for the restoration and substitution of lost and impaired functions for these users. In this s...\",\n \"Title: ROS-health: An open-source framework for neurorobotics\\nYear: 2018\\n\\nAbstract: This paper aims at providing a preliminary description of ROS-Health, a novel framework for neurorobotics based on the middleware Robot Operating System (ROS). The increased interest in the neurorobotics field and the proliferation of several (neuro)physiological-based applications to control robotics devices made clear the importance to establish a standardized research platform in order to facilitate the distribution of the software, the replication of experimental results and the creation of an unified community to share and manage the code in the years. For this reason, we propose a common platform developed in the ROS ecosystem that takes advantage of its tools and capabilities. Furthermore, we describe the design guidelines that we are following in the preliminary definition of ROS-Health architecture. Finally, we present two illustrative use cases that highlight the advantages and benefits of the adoption of ROS-Health.\",\n \"Title: Sensory threshold neuromuscular electrical stimulation fosters motor imagery performance.\\nYear: 2018\\n\\nAbstract: Motor imagery (MI) has been largely studied as a way to enhance motor learning and to restore motor functions. Although it is agreed that users should emphasize kinesthetic imagery during MI, recordings of MI brain patterns are not sufficiently reliable for many subjects. It has been suggested that the usage of somatosensory feedback would be more suitable than standardly used visual feedback to enhance MI brain patterns. However, somatosensory feedback should not interfere with the recorded MI brain pattern. In this study we propose a novel feedback modality to guide subjects during MI based on sensory threshold neuromuscular electrical stimulation (St-NMES). St-NMES depolarizes sensory and motor axons without eliciting any muscular contraction. We hypothesize that St-NMES does not induce detectable ERD brain patterns and fosters MI performance. Twelve novice subjects were included in a cross-over design study. We recorded their EEG, comparing St-NMES with visual feedback during MI or resting tasks. We found that St-NMES not only induced significantly larger desynchronization over sensorimotor areas (p<0.05) but also significantly enhanced MI brain connectivity patterns. Moreover, classification accuracy and stability were significantly higher with St-NMES. Importantly, St-NMES alone did not induce detectable artifacts, but rather the changes in the detected patterns were due to an increased MI performance. Our findings indicate that St-NMES is a promising feedback in order to foster MI performance and cold be used for BMI online applications.\",\n \"Title: Decoding Neural Correlates of Cognitive States to Enhance Driving Experience.\\nYear: 2018\\n\\nAbstract: Modern cars can support their drivers by assessing and autonomously performing different driving maneuvers based on information gathered by in-car sensors. We propose that brain- machine interfaces (BMIs) can provide complementary information that can ease the interaction with intelligent cars in order to enhance the driving experience. In our approach, the human remains in control, while a BMI is...\",\n \"Title: Motor Attempt EEG Paradigm as a Diagnostic Tool for Disorders of Consciousness.\\nYear: 2018\\n\\nAbstract: To investigate whether a motor attempt EEG paradigm coupled with functional electrical stimulation can detect command following and, therefore, signs of conscious awareness in patients with disorders of consciousness, we recorded nine patients admitted to acute rehabilitation after a brain lesion. We extracted peak classification accuracy and peak session discriminant power (PSDP) and we assessed their correlation to the established coma recovery scale revised (CRS-R) and the agreement with diagnosis based on the novel motor behavior tool (MBT). Only PSDP correlated significantly with CRS-R and it also outperformed peak accuracy regarding the MBT. We conclude that PSDP might be more suitable than accuracy to complement CRS-R and MBT in evaluating ambiguous cases and in detecting cognitive motor dissociation.\",\n \"Title: Using Robust Principal Component Analysis to Reduce EEG Intra-Trial Variability.\\nYear: 2018\\n\\nAbstract: Practical brain-computer interfaces need to overcome several challenges, including tolerance to signal variability within- and across sessions. We introduce Robust Principal Component Analysis (RPCA) as a potential approach to tackle intra-trial variability. Assuming that subjects undergo the same cognitive process or perform the same task in a short period (e.g., a few seconds), as a result, the signal of interest should be represented by only a few components. We verified this approach on a workload detection task, where subjects needed to pilot a simulated drone. We used RPCA as a processing step to decrease trial variability and assessed its impact on classification accuracy. Our results showed that RPCA significantly increased performance in both at group and subject level analysis. On average, class-balanced accuracy when simulating RPCA online increased from 63.9% up to 70.6% $(p~ 0 . 001)$.\",\n \"Title: Exploring Embedding Methods in Binary Hyperdimensional Computing: A Case Study for Motor-Imagery based Brain-Computer Interfaces.\\nYear: 2018\\n\\nAbstract: Key properties of brain-inspired hyperdimensional (HD) computing make it a prime candidate for energy-efficient and fast learning in biosignal processing. The main challenge is however to formulate embedding methods that map biosignal measures to a binary HD space. In this paper, we explore variety of such embedding methods and examine them with a challenging application of motor imagery brain-computer interface (MI-BCI) from electroencephalography (EEG) recordings. We explore embedding methods including random projections, quantization based thermometer and Gray coding, and learning HD representations using end-to-end training. All these methods, differing in complexity, aim to represent EEG signals in binary HD space, e.g. with 10,000 bits. This leads to development of a set of HD learning and classification methods that can be selectively chosen (or configured) based on accuracy and/or computational complexity requirements of a given task. We compare them with state-of-the-art linear support vector machine (SVM) on an NVIDIA TX2 board using the 4-class BCI competition IV-2a dataset as well as a new 3-class dataset. Compared to SVM, results on 3-class dataset show that simple thermometer embedding achieves moderate average accuracy (79.56% vs. 82.67%) with 26.8$times$ faster training time and 22.3$times$ lower energy; on the other hand, switching to end-to-end training with learned HD representations wipes out these training benefits while boosting the accuracy to 84.22% (1.55% higher than SVM). Similar trend is observed on the 4-class dataset where SVM achieves on average 74.29%: the thermometer embedding achieves 89.9$times$ faster training time and 58.7$times$ lower energy, but a lower accuracy (67.09%) than the learned representation of 72.54%.\",\n \"Title: Hyperdimensional Computing for Blind and One-Shot Classification of EEG Error-Related Potentials\\nYear: 2020\\n\\nAbstract: The mathematical properties of high-dimensional (HD) spaces show remarkable agreement with behaviors controlled by the brain. Computing with HD vectors, referred to as “hypervectors,” is a brain-inspired alternative to computing with numbers. HD computing is characterized by generality, scalability, robustness, and fast learning, making it a prime candidate for utilization in application domains such as brain–computer interfaces. We describe the use of HD computing to classify electroencephalography (EEG) error-related potentials for noninvasive brain–computer interfaces. Our algorithm naturally encodes neural activity recorded from 64 EEG electrodes to a single temporal–spatial hypervector without requiring any electrode selection process. This hypervector represents the event of interest, can be analyzed to identify the most discriminative electrodes, and is used for recognition of the subject’s intentions. Using the full set of training trials, HD computing achieves on average 5% higher single-trial classification accuracy compared to a conventional machine learning method on this task (74.5% vs. 69.5%) and offers further advantages: (1) Our algorithm learns fast: using only 34% of training trials it achieves an average accuracy of 70.5%, surpassing the conventional method. (2) Conventional method requires prior domain expert knowledge, or a separate process, to carefully select a subset of electrodes for a subsequent preprocessor and classifier, whereas our algorithm blindly uses all 64 electrodes, tolerates noises in data, and the resulting hypervector is intrinsically clustered into HD space; in addition, most preprocessing of the electrode signal can be eliminated while maintaining an average accuracy of 71.7%.\",\n \"Title: Human EEG reveals distinct neural correlates of power and precision grasping types.\\nYear: 2018\\n\\nAbstract: Hand grasping is a sophisticated motor task that has received much attention by the neuroscientific community, which demonstrated how grasping activates a network involving parietal, pre-motor and motor cortices using fMRI, ECoG, LFPs and spiking activity. Yet, there is a need for a more precise spatio-temporal analysis as it is still unclear how these brain activations over large cortical areas evolve at the sub-second level. In this study, we recorded ten human participants (1 female) performing visually-guided, self-paced reaching and grasping with precision or power grips. Following the results, we demonstrate the existence of neural correlates of grasping from broadband EEG in self-paced conditions and show how neural correlates of precision and power grasps differentially evolve as grasps unfold. 100 ms before the grasp is secured, bilateral parietal regions showed increasingly differential patterns. Afterwards, sustained differences between both grasps occurred over the bilateral motor and parietal regions, and medial pre-frontal cortex. Furthermore, these differences were sufficiently discriminable to allow single-trial decoding with 70% decoding performance. Functional connectivity revealed differences at the network level between grasps in fronto-parietal networks, in terms of upper-alpha cortical oscillatory power with a strong involvement of ipsilateral hemisphere. Our results supported the existence of fronto-parietal recurrent feedback loops, with stronger interactions for precision grips due to the finer motor control required for this grasping type.\",\n \"Title: Non-invasive estimation of local field potentials for neuroprosthesis control\\nYear: 2005\\n\\nAbstract: Recent experiments have shown the possibility of using the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions, i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using an identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using a different number of electrodes.\",\n \"Title: Reliable decoding of motor state transitions during imagined movement\\nYear: 2019\\n\\nAbstract: Current non-invasive Brain Machine interfaces commonly rely on the decoding of sustained motor imagery activity. This approach enables a user to control brain-actuated devices by triggering predetermined motor actions. However, despite of its broad range of applications, this paradigm has failed so far to allow a natural and reliable control. As an alternative approach, we investigated the decoding of states transitions of an imagined movement, i.e. rest-to-movement (onset) and movement-to-rest (offset). We show that both transitions can be reliably decoded with accuracies of 71.47% for the onset and 73.31% for the offset (N = 9 subjects). Importantly, these transitions exhibit different neural patterns and need to be decoded independently. Our results indicate that both decoders are able to capture the brain dynamics during imagined movements and that their combined use could provide benefits in terms of accuracy and time precision.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":71,"string":"71"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":76,"string":"76"}}},{"rowIdx":77,"cells":{"question_id":{"kind":"string","value":"Zaichen Zhang"},"question":{"kind":"string","value":"Generate an abstract for the title \"Polarity Information Coded Flip-OFDM for Intensity Modulated Systems.\" using the following items: 1. Polarity-information-coded \n2. Orthogonal frequency division multiplexing \n3. Intensity modulation/direct detection \n4. Higher spectral and optical power efficiencies \n5. Simulations"},"answer":{"kind":"string","value":"A polarity-information-coded flip orthogonal frequency division multiplexing is proposed for intensity modulation/direct detection optical communications in this letter. In the proposed scheme, the modulated signals in the frequency domain are not constrained to have Hermitian symmetry. The real and imaginary parts of the time-domain complex signals are separated, and the polarities of the real and imaginary parts are jointly encoded and modulated. The transmit strategy and the receive algorithm of the proposed scheme are analyzed in detail. The major advantage of the proposed scheme is that its spectral and optical power efficiencies are higher than existing schemes, which is validated in simulation."},"correct_answer":{"kind":"string","value":"A polarity-information-coded flip orthogonal frequency division multiplexing is proposed for intensity modulation/direct detection optical communications in this letter. In the proposed scheme, the modulated signals in the frequency domain are not constrained to have Hermitian symmetry. The real and imaginary parts of the time-domain complex signals are separated, and the polarities of the real and imaginary parts are jointly encoded and modulated. The transmit strategy and the receive algorithm of the proposed scheme are analyzed in detail. The major advantage of the proposed scheme is that its spectral and optical power efficiencies are higher than existing schemes, which is validated in simulation."},"documents":{"kind":"list like","value":["Title: Adaptive primary user's signal detection algorithm based on matrix accumulation estimation for cognitive radio.\nYear: 2011\n\nAbstract: In this article, a new adaptive primary user's signal detection algorithm for cognitive radio, which integrates frequency-domain block adaptive filtering with a matrix accumulation estimation, is presented with detailed description' of the concept and process of the algorithm. Then, the performance of the algorithm is analyzed and compared by simulation according to the practical requirement of cognitive radio. The result shows that the proposed detection algorithm can detect weak signals quickly and effectively with higher detection probability.","Title: Router-Assisted Layered Multicast\nYear: 2002\n\nAbstract: Several layered multicast protocols have been proposed for congestion control in real-time multicast applications. Most of them are pure end-to-end protocols, thus having difficulty In coordinating receivers and coping with traffic variations. In this paper, we propose RALM, a new receiver-driven router-assisted layered multicast protocol. RALM achieves much better performance at the expense of moderate additional complexity in the network. RALM is incrementally deployable. We evaluate RALM through simulations, and compare its performance with RLM, the well known layered multicast protocol.","Title: On grouped OFDM-IDMA\nYear: 2011\n\nAbstract: A generalized version of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) referred to as grouped OFDM-IDMA (G-OFDM-IDMA) is introduced in this paper. By dividing the users into several groups and transmitting each group's data only on part of the subcarriers, the G-OFDM-IDMA system is capable of having much lower decoding complexity compared with the conventional OFDM-IDMA while preserving the bandwidth efficiency and the bit error rate (BER) performance. We study the performance of the proposed scheme in terms of the decoding complexity and diversity order. We also extend the results to the multiple receive antennae case. Simulations are performed to corroborate the performance of the proposed G-OFDM-IDMA.","Title: Modulation Scheme Based on Precoder Matrix for MIMO Optical Wireless Communication Systems.\nYear: 2012\n\nAbstract: A modulation scheme for multiple-input multiple-output (MIMO) optical wireless systems that employ intensity modulation (IM) is proposed. This scheme, called precoder matrix modulation (PMM), exploits the properties of MIMO optical wireless communications to translate the spatial dimension into the constellation parameters by using a 'precoder matrix'. The transmitted signals in PMM are guaranteed to be nonnegative, as required in IM optical wireless communications. Existing schemes such as pulse-amplitude modulation could be used in such systems, but the proposed scheme has a much better performance. The constellation size of PMM can be flexibly increased, mitigating the bandwidth shortage issue due to the limitation of light emitting diodes (the transmitters). © 2012 IEEE.","Title: Internet multicast routing and transport control protocols\nYear: 2002\n\nAbstract: Multicasting is a mechanism to send data to multiple receivers in an efficient way. We give a comprehensive survey on network and transport layer issues of Internet multicast. We begin with an introduction to the current Internet protocol multicast model-the "host group" model and the current Internet multicast architecture, then discuss in depth the following three research areas: (1) scalable mu...","Title: An Efficient Joint Timing And Frequency Offset Estimation For Ofdm Systems\nYear: 2009\n\nAbstract: This paper presents a new joint frame synchronization and frequency offset estimation algorithm for orthogonal frequency division multiplexing (OFDM) systems as a modification to Zhang's method [1]. By designing a new training preamble weighted by PN sequence, the timing estimator is improved (at least 3dB with low SNR). By estimating time offset first, the computational load is greatly reduced with no loss in frequency offset estimation accuracy. The performance of the proposed method is evaluated by computer simulations in terms of timing error rate (TER) together with computational complexity.","Title: OFDM-IDMA with User Grouping\nYear: 2013\n\nAbstract: A generalized version of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) referred to as grouped OFDM-IDMA (G-OFDM-IDMA) is introduced in this paper. By dividing users into groups and transmitting each group's data only on some (as opposed to all) subcarriers, G-OFDM-IDMA can have much lower decoding complexity compared with conventional OFDM-IDMA while preserving the bit error probability (BEP) performance and the bandwidth efficiency. The user grouping problem is formulated into an integer linear programming problem whose suboptimal solution is proposed and compared with the lower bound. The optimization complexity issue is also addressed. Simulations are carried out to test the performance of G-OFDM-IDMA under various system configurations. It is observed that up to 80% complexity could be saved when the conventional OFDM-IDMA is substituted by G-OFDM-IDMA configured according to the suboptimal grouping solution.","Title: Adaptive modulation with finite rate feedback for QR decomposition-successive interference cancellationbased multiple-in multiple-out systems\nYear: 2013\n\nAbstract: This article studies adaptive modulation for QR decomposition and successive interference cancellation receivers in multiple-input multiple-output systems over slow- and fast-fading channels. In slowly fading channels, adaptive modulation schemes with finite-rate feedback under the constraints of a constant total transmit power, discrete-rate and a target bit-error-rate (BER) are proposed. Specifically, the authors first develop adaptive modulation with modulation order feedback only. For power allocation and modulation order feedback, the authors establish an optimisation scheme that can be solved easily and analyse the effect of power-level quantisation on the achievable data rates. For the fast fading channel case, the authors analyse the probability distribution of the `R' matrix and derive a scheme that only requires feedback of the statistical information of the channel for adaptive modulation with optimal bit loading to guarantee that the BER target is met.","Title: Network-Supported Layered Multicast Transport Control for Streaming Media\nYear: 2007\n\nAbstract: Multicast is very efficient in distributing a large volume of data to multiple receivers over the Internet. Layered multicast helps solve the heterogeneity problem in multicast delivery. Extensive work has been done in the area of layered multicast, for both congestion control and error control. In this paper, we focus on network-supported protocols for streaming media. Most of the existing work solves the congestion control and error control problems separately and does not give an integrated efficient solution. In this paper, after reviewing related work, we introduce our proposed protocols, namely, router-assisted layered multicast (RALM) and router-assisted layered FEC (RALF). The former is a congestion control protocol, whereas the latter is an error control protocol. They work under the same framework and provide an integrated solution. We also extend RALM to RALM-II, which is compatible with transmission control protocol (TCP) traffic. We analyze the complexity of the proposed protocols in the network and investigate their performance through simulations. We show that our solution achieves significant performance gains with reasonable additional complexity.","Title: A joint channel estimation and synchronization algorithm for high speed digital IR-UWB system\nYear: 2010\n\nAbstract: This letter proposes a joint channel estimation and synchronization algorithm for impulse radio ultra-wideband (IRUWB) communication. High-speed sampling and 1-bit quantization at the receiver are assumed to achieve high data rate with reasonable complexity. Simulation results show that the proposed algorithm works well when inter-symbol interference (ISI) is ignored during the preamble period.","Title: Improved SNR Evolution for OFDM-IDMA Systems\nYear: 2012\n\nAbstract: The bit error rate performance of interleave division multiple access (IDMA) based systems can be predicted by signal-to-noise ratio (SNR) evolution which tracks the average symbol SNR at each iteration and provides a faster solution than brute-force simulations. As the desired SNR in the evolution procedure is hard to obtain, approximate SNR updating formula has been widely adopted in the literature. In this paper a revised SNR updating formula is proposed for orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems in Rayleigh fading channels. Theoretical analysis shows that the new updating formula provides a tighter lower bound of the expected SNR in the evolution procedure compared with the existing one. We then verified this by simulations.","Title: Symbol Detection of IDMA Systems in the Presence of Carrier Frequency Offsets\nYear: 2013\n\nAbstract: In this paper we investigate the detection algorithms for interleave division multiple access (IDMA) systems in the presence of carrier frequency offsets (CFOs). The existing IDMA detection algorithm is designed under the zero CFO assumption and its performance will be degraded when the CFOs are present. We first extend the existing algorithm to the nonzero CFO case by utilizing effective channel coefficients which take the CFO effects into account. Then we turn to a more practical scenario with imperfect CFO estimates. We propose an algorithm that can cope with the residual CFO effects by integrating the CFO updating into the iterative receiver. Signal-to-interference-plus-noise ratio analysis and simulations show the feasibility and superiority of our proposed algorithms.","Title: Mimo-Ofdm Visible Light Communications System With Low Complexity\nYear: 2013\n\nAbstract: In visible light communication (VLC) systems with intensity modulation (IM) and direct detection (DD), the modulation bandwidth of light emitting diode (LED) is limited, and dispersion of the channel might cause inter-symbol interference. Also, the transmitted signal must be nonnegative. Thus most modulation schemes for radio communications cannot be used directly for such a system. This paper develops a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) VLC system that overcomes the modulation bandwidth limitation of LED and satisfies the requirements of the transmitted signal for IM/DD. Also, two transmit data streams require only one inverse discrete Fourier transform (IDFT) block, resulting in a low computational complexity. The transmitter architecture, receive algorithm, bit error rate performance, channel capacity analysis, and simulation results are provided.","Title: A New View on Channel Capacity of MISO Frequency Selective Channels.\nYear: 2011\n\nAbstract: A new view of multiple-input and single-output (MISO) technology in the frequency selective channels has been expressed in this letter. The definition of the virtual multiple receive antennas is proposed, which shows the maximum degree of freedom in the MISO frequency selective channel is more than one. Analytical and simulation results show that channel capacity can be improved by increasing the number of transmit antennas in the MISO frequency selective environment.","Title: A Novel Receiver for ACO-OFDM in Visible Light Communication.\nYear: 2013\n\nAbstract: This letter proposes a novel receiver for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) system in visible light communication to enhance its performance. In ACO-OFDM, the even subcarriers are distorted by the clipping noise and are simply discarded in the conventional receiver. In this letter we show that the signals on the even subcarriers can be viewed as data-dependent precoded OFDM. A novel receiver based on minimum mean square error criteria is then proposed to exploit the even subcarriers to collect additional diversity and coding gains, leading to improved bit error rate performance. Simulations show that the proposed receiver provides significant signal-to-noise ratio gain (up to 10 dB) over the conventional receiver, especially in non-line-of-sight channels. Moreover, the proposed receiver is also superior to some existing advanced ones. © 1997-2012 IEEE.","Title: Two-level multicarrier UWB: A case study\nYear: 2010\n\nAbstract: In our previous work we have proposed a new ultra-wideband (UWB) communication scheme referred to as two-level multicarrier (TLMC) UWB. TLMC UWB has some structurally inherited advantages compared to the conventional multiband orthogonal frequency division multiplexing UWB scheme, which make it a promising candidate for future ultra-high speed communications. However, in that work we presented the proposed scheme in a general manner. In this paper we study a specific type of TLMC UWB which is based on exponentially modulated filter banks. We will elaborate the system model and investigate the equalization task in detail. System performance is also evaluated through computer simulation.","Title: A simulated method of modeling wireless channel based on CDL\nYear: 2010\n\nAbstract: Rapid development of wireless communications gives prominence to simulation. Simulated methods of modeling wireless channel are of significance to wireless communications simulation on both link and system levels. There have been quite a lot of theoretical models which have accurately described the characteristics of wireless channel. However when it comes to the realization of wireless channel in simulation, there seem no accurate enough methods and conclusions. Current simulated methods are mostly built up based on TDL, which is a common framework to model micro fading and mainly focused on micro fading. As to macro fading, Doppler-effect and polarization of electromagnetic wave, this method behaves not well enough, and other statistical approximations is indispensable, such as shadow fading, Doppler power spectrum density and so on. To the question existed, this paper proposes a simulated method to accurately model wireless channel under given wireless environment, on the basis of cluster delay line. This method is highlighted with comprehensive consideration of macro and micro fading, Doppler, multi-path and polarization effect. Analysis and simulation results on characteristics of wireless channel such as signal envelope, coherent time and bandwidth, validate the proposed model. ©2010 IEEE.","Title: Design of indoor optical wireless collaborative cellular system.\nYear: 2011\n\nAbstract: In this paper, we propose a non-imaging method to implement the indoor optical wireless cellular system. Design of base stations and portable devices are presented and analyzed. Our design combining some collaborative schemes can improve SISO performance. Based on our proposed system, non-imaging MIMO techniques can perform properly at all receiver positions. © 2011 IEEE.","Title: OFDM-IDMA communications over underwater acoustic channels\nYear: 2011\n\nAbstract: The combination of orthogonal frequency division multiplexing (OFDM) and interleave division multiple access (IDMA), known as OFDM-IDMA, has been proposed as a promising multiple access scheme for wireless communications due to its low decoding complexity and potential of achieving high spectral efficiency. However, most of the work on OFDM-IDMA is in radio frequency (RF) communications scenarios and based on computer simulations. In this paper, we propose OFDM-IDMA over underwater acoustic (UWA) channels with experimental results. We also extend the original OFDM-IDMA to a multiple hydrophones scenario to improve the bit error rate (BER) performance. Experimental results show that with multiple hydrophones, the coded BER performance of OFDM-IDMA approaches zero after only a few iterations, validating the feasibility of our proposed approach over UWA channels.","Title: Transmit Beamforming for MIMO Optical Wireless Communication Systems\nYear: 2014\n\nAbstract: This paper focuses on transmit beamforming for multiple-input multiple-output optical wireless communication (OWC) systems with intensity modulation and direct detection (IM/DD). OWC with IM/DD requires the transmitted signals to be nonnegative, for which existing beamforming schemes developed for radio frequency systems cannot be applied directly. We propose effective schemes for OWC over frequency flat and frequency selective channels. For frequency flat fading, the property of the beamforming vector is derived. For frequency selective fading, bit-error rate performances of the proposed scheme with zero-forcing and minimum mean-square error frequency domain equalization receivers are derived, and a suboptimal beamforming vector for frequency selective fading channels is proposed. Compared with asymmetrically clipped optical orthogonal frequency division multiplexing based frequency domain beamforming, the proposed scheme needs much less feedback information and has a better error performance.","Title: An Optimum DC-Biasing for DCO-OFDM System.\nYear: 2014\n\nAbstract: Selecting an appropriate direct current (dc) bias is crucial to obtain positive and low-peak-to-average-power-ratio electrical signals in the dc optical orthogonal frequency-division multiplexing (DCO-OFDM) system. In this letter, our goal is to propose an optimization strategy of dc bias under given lower and upper clipping bounds. We characterize the mean square error between the original signals and the clipped ones as the metric of clipping distortion. Finding the optimum dc bias can be formulated as a nonconvex optimization problem. However, the optimum dc bias can be obtained from a numerical method. The simulation results show that the bit error ratio performance can be improved when employing the optimum dc bias obtained by the proposed numerical method.","Title: Comparison of optical OFDM-IDMA and optical OFDMA for uplink visible light communications\nYear: 2012\n\nAbstract: In this paper we compare two candidate multiple access schemes for visible light communications (VLC), namely, optical orthogonal frequency division multiplexing interleave division multiple access (O-OFDM-IDMA) and optical orthogonal frequency division multiple access (O-OFDMA). Both of them belong to multicarrier transmission schemes and are tailored for VLC channels by asymmetrically clipping at zero after OFDM modulation. We compare their bit error rate (BER) performance, receiver complexities as well as peak-to-average power ratios (PAPRs) in different scenarios. Simulations show that O-OFDM-IDMA is more power efficient than O-OFDMA, especially for higher throughput, at the cost of higher computational complexity. The PAPRs of O-OFDM-IDMA and O-OFDMA do not show much difference. Those results provide a useful guidance for the design of future networks based on VLC.","Title: Optimal symmetric double-sided signal clipping in DCO-OFDM visible light communication\nYear: 2014\n\nAbstract: In this paper, the optimal DC bias value of symmetric double-sided signal clipping in DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) visible light communication (VLC) system is deduced. Double-sided clipping is necessary due to the unipolarity of the optical intensity-modulated, direct-detected (IM/DD) system and power limit of the transmitter. Symmetric double-sided clipping is adopted to achieve wider dynamic range. Clipping noise is analyzed for system performance investigation. The optimal DC bias value is deduced by minimizing the system bit error ratio (BER) at given transmitter optical power. An equation of signal to noise ratio (SNR), signal energy, and optimal DC bias value is derived. Finally, the optimal algorithm is verified through a BER simulation at different DC bias values.","Title: Lower bounds on the capacity for Poisson optical channel\nYear: 2014\n\nAbstract: New reliable and accurate capacity bounds for Poisson channel modeled optical communication system are derived under peak-power and average-power constraints. The bounds are based on two entropy inequalities of Poisson random variables. Simulation results show that the proposed bounds are much tighter than previous ones, especially at lower signal-to-noise (SNR) region, where most wireless optical links typically operate.","Title: A low complexity receiver for OFDM-IDMA with multiple carrier frequency offsets\nYear: 2014\n\nAbstract: The performance of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems would be severely degraded by the inter-carrier interference (ICI) which is caused by multiple carrier frequency offsets (CFOs). Existing receivers with CFO mitigation capabilities either have extremely high complexities or suffer from performance loss compared with the conventional receiver in the absence of CFOs. In this paper we propose a new receiver suitable for OFDM-IDMA in the presence of multiple CFOs. By properly performing soft interference cancellation (SIC) and variance approximation, the proposed receiver is capable of completely eliminating the CFO effects with a much lower complexity which is comparable with the zero CFO case. Both signal-to-interference-plus-noise ratio (SINR) and complexity analysis are conducted to theoretically validate the idea of the proposed receiver. Simulation results are also presented to compare the proposed receiver with existing ones. It is shown that the proposed receiver is a strong candidate for OFDM-IDMA with CFOs in practice.","Title: SoftOC: Real-time projector-wall-camera communication system\nYear: 2013\n\nAbstract: Camera-equipped consumer electronics tend to become cheaper and cheaper currently. These cameras can provide high-speed communication links to combat the shortage of radio spectrum. This paper introduces SoftOC, a novel real-time projector-wall-camera communication system. We name our system software optical communication (SOC) system. In order to improve the reliability of these systems and to speed up the computing process, we propose some schemes. We verify the effectiveness of our proposed schemes on real-time communication prototype.","Title: DNA Computing for Combinational Logic.\nYear: 2018\n\nAbstract: With the progressive scale-down of semiconductor’s feature size, people are looking forward to More Moore and More than Moore. In order to offer a possible alternative implementation process, researchers are trying to figure out a feasible transfer from silicon to molecular computing. Such transfer lies on bio-based modules programming with computer-like logic, aiming at realizing the Turing machine. To accomplish this, the DNA-based combinational logic is inevitably the first step we have taken care of. This timely overview study introduces combinational logic synthesized in DNA computing from both analog and digital perspectives separately. State-of-the-art research progress is summarized for interested readers to quick understand DNA computing, initiate discussion on existing techniques and inspire innovation solutions. We hope this study can pave the way for the future DNA computing synthesis.","Title: Data rate optimization in inter-cell interference environment of visible light communication\nYear: 2016\n\nAbstract: Abstract This paper investigates the higher-order modulation using Hadamard matrix to improve the data rate performance, particularly in the interference regions of a multi-cell environment in visible light communication. It presents a novel scheme which utilizes Hadamard matrix to produce orthogonal pulses (OPs) that mitigate the inter-cell interference, and covers the interference areas of the room for mobile receivers. The minimum power requirements is examined to achieve optimum data rate in whole area of the room. Moreover, the signal-to-noise ratio is derived to provide the similar capacity distribution between cells. Theoretical analysis and simulation experiments of bit error rate (BER) and capacity performances are conducted and three arrangements of signals in cells are compared, which are defined as all cells use different sets of OPs (DSOPs), all cells use the same set of OPs (SSOPs) and reuse OPs in diagonal (ROPD) cells of the room. The results show that the BER performance of DSOPs is \\(10^{-2.7}\\) at the high interference area, which is the best performance compared to ROPD and SSOPs. Moreover, DSOPs requires less power to achieve 2, 3 and 4 bits/symbol compared to ROPD and SSOPs.","Title: DC and non-DC biased optical filter bank multicarrier communication for IM/DD channel\nYear: 2016\n\nAbstract: This paper proposes two filter bank multicarrier (FBMC) schemes for optical communication in intensity modulation direct detection (IM/DD) channel with and without direct current (DC) bias. The aim is to overcome some inherent drawbacks of the commonly used optical orthogonal frequency division multiplexing (OFDM) schemes. Key transceiver principles are designed to accommodate the requirements of IM/DD channel. Various performance metrics are analyzed and compared with optical OFDM schemes. It is found that the proposed schemes are more spectral and power efficient than their optical OFDM counterparts. In addition, the DC-biased optical FBMC scheme fully supports asynchronized multiuser uplink transmission, which is another pronounced advantage over the optical OFDM schemes that require stringent synchronization to maintain orthogonality. The analysis is confirmed by simulations. The findings may shed light into potential research line on FBMC based IM/DD optical communications.","Title: A New Framework for Non-orthogonal Multiple Access Based on Generalized Energy Spreading Transform.\nYear: 2016\n\nAbstract: With the increasing needs of high data rate communication, spectrally more efficient communication schemes are desired. In multiuser communication context, conventional orthogonal multiple access (OMA) schemes suffer from spectral efficiency loss by fundamental information theoretics. Non-orthogonal multiple access (NOMA) schemes are more appropriate. In this paper, we propose a new NOMA system based on generalized energy spreading transform (GEST). We give the basic system structure and compare it with some existing NOMA systems. It is interesting that the proposed GEST-MA can be viewed as a generalization of several existing NOMA systems. Analysis and simulations show that GEST-MA is more flexible than current NOMA systems and is capable of achieving the potential diversity gain without sacrificing the spectral efficiency. Those properties make it a strong candidate for the next generation mobile communication systems.","Title: Properties and achievable data rate of a cyclic prefix based imperfect reconstruction filter bank multiple access system.\nYear: 2016\n\nAbstract: In this study, the authors propose a cyclic prefix (CP) based imperfect reconstruction (IPR) filter bank multicarrier (FBMC) system in the uplink of multiuser networks, known as filter bank multiple access (FBMA). The prototype filter in the system is a common low-pass filter without any perfect reconstruction (PR) or nearly perfect reconstruction (NPR) constraint. CP appended input signal format ...","Title: Subcarrier-wise power allocation for OFDM-IDMA systems\nYear: 2015\n\nAbstract: Current orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems only employ the power optimization process in the user-wise level but the subcarrier-wise level remains untouched. This paper proposes a novel and efficient algorithm for subcarrier-wise power allocation in OFDM-IDMA system, which aims at maximizing the channel capacity under the constraints of user-wise average powers. Different from the widely used channel capacity formula, the objective function is changed from capacity of Gaussian inputs to capacity of quadrature phase shift keying (QPSK) modulated inputs. Comparisons with other alternative algorithms such as equal power allocation algorithm and water filling power allocation algorithm are provided. Simulation results show that the proposed algorithm can achieve better and more robust BER performance.","Title: Upper bounds on the capacity for optical intensity channels with AWGN.\nYear: 2017\n\nAbstract: The channel capacity of the optical wireless communication (OWC) systems is still a problem that has not an optimal and close-form expression, in spite of OWC can be used to achieve high data rates. This paper presents novel upper bounds on the channel capacity of an optical intensity modulated and directed detection (IM/DD) system under peak-power and average-power constraints. The channel is modeled as an additive white Gaussian noise (AWGN) optical channel. The bounds are derived based on sphere-based signal space argument. Simulation results show the proposed bounds are tight at both high and low signal-to-noise ratios (SNRs). Compared to those reported bounds, the derived bounds are better at high SNRs region in particular, and the expressions are simpler and unique for the whole range of average-to-peak-power ratio.","Title: Blind Interference Alignment in Two-Cell Z Interference MIMO Channel.\nYear: 2017\n\nAbstract: This paper proposes a blind interference alignment (BIA) scheme in two-cell Z interference multiple-input multiple-output channel where the cell edge user equipment (UE) of the first cell is interfered by the base station of the second cell during downlink transmissions, while the UE of the second cell is free from inter-cell interference. By employing the reconfigurable antennas at receivers, the transmit strategy of the proposed scheme is designed. The achievable degree of freedom (DoF), the achievable rates, and the bit error rate performance of the proposed BIA scheme are analyzed. Simulation results show that the achievable DoF and the throughput of the proposed scheme are improved compared with conventional interference control scheme. Furthermore, in the proposed BIA scheme, all UEs can achieve a good diversity gain to combat fading.","Title: Blind Interference Alignment for Multiuser MISO Indoor Visible Light Communications.\nYear: 2017\n\nAbstract: A filter-pair-based blind interference alignment scheme is proposed to improve the achievable degree of freedom (DoF) in multiuser multiple-input single-output indoor visible light communications. In the proposed scheme, the transmitter does not need to know channel state information. Different transmit sub-channels employ different pulse-shaping filters, and each user is equipped with multiple receive filters. The transmitter sends signals according to the predesigned strategy, and each user sets the receive mode by choosing the corresponding receive filter. Optical orthogonal frequency division multiplexing is employed in the proposed scheme to combat the intersymbol interference in high-speed transmissions, and the maximum achievable spectrum efficiency (SE) of the proposed scheme is analyzed. Simulation results validate that the proposed scheme can achieve higher SE and more DoF than the orthogonal multiple access schemes.","Title: Approximate Message Passing-Based Joint User Activity and Data Detection for NOMA.\nYear: 2017\n\nAbstract: This letter focuses on joint user activity and data detection in the uplink grant-free non-orthogonal multiple access systems based on approximate message passing (AMP) and expectation maximization (EM) algorithms. The proposed Joint-EM-AMP detection algorithm consists of three steps in each iteration. First, AMP decouples the superimposed received signal into uncoupled scalar problems. Then, at t...","Title: Analysis of Geometric Multibounced Virtual Scattering Channel Model for Dense Urban Street Environments.\nYear: 2017\n\nAbstract: This paper presents a generalized visual scattering channel model for car-to-car (C2C) mobile radio environments, in which an asymmetric directional antenna is deployed at the mobile transmitter (MT). The signals received at the mobile receiver (MR) from the MT are assumed to experience multibounced propagation paths. More importantly, the proposed model first separates the multibounced propagatio...","Title: Optical mobile communications: Principles and challenges\nYear: 2017\n\nAbstract: Optical wireless communication (OWC) is position sensitive and deemed not suitable for ultra-high throughput mobile communications. In this paper, we propose an optical mobile communication (OMC) system, which dynamically allocates optical beams to mobile users and tracks the users adaptively, thus extends OWC to mobile scenarios. Principles of OMC is introduced and several key design problems are discussed.","Title: Enhanced time-shifted pilot based channel estimation in massive MIMO systems with finite number of antennas\nYear: 2017\n\nAbstract: Time-shifted pilot scheme can efficiency combat pilot contamination. However, when the number of base station (BS) antennas is finite, the pilot interference due to the downlink transmission symbols cannot be mitigated in the time-shifted scheme. This paper proposed a novel two-stage channel estimation algorithm based on time-shifted pilot to reduce the effect of pilot interference. In the first stage, beamforming vectors are determined to reduce the interference from other cells by introducing null symbol periods. Then, receive beamforming is carried out. In the second stage, channel estimation is performed. In the proposed scheme, the pilots of different users in the same cell are orthogonal and the pilots are reused in other cells. The proposed scheme can reduce the effect of pilot interference and improve spectrum efficiency, when the number of BS antennas is finite. The proposed channel estimation algorithm is presented in detail, and the channel estimation performance and achievable spectrum efficiency are analyzed. Simulation results validate the proposed scheme.","Title: Expectation-Propagation Based Low-Complexity Channel Estimation For Massive Mimo Systems\nYear: 2017\n\nAbstract: In this paper we propose a low-computational-complexity channel estimation algorithm for the downlink of massive MIMO systems. This algorithm employs the expectation propagation and expectation maximization techniques, assuming a sparsity promoting conditional Gaussian prior distribution on the channels. Its computational complexity scales only linearly with the number of transmit antennas, the number of pilots, and the channel length. Compared with existing state-of-the-art algorithms, it has a lower pilot overhead and is much more computationally efficient. The channel estimation mean-squared errors with the proposed algorithm and the existing block iterative support detection (block-ISD) and basic pursuit (BP) methods are simulated and compared. Results show that the performance of the proposed algorithm approaches the benchmark performance, and is significantly better than that of block-ISD and BP.","Title: Channel Estimation for Multicell Multiuser Massive MIMO Uplink Over Rician Fading Channels.\nYear: 2017\n\nAbstract: Pilot contamination (PC) is a major problem in massive multiple-input multiple-output (MIMO) systems. This paper proposes a novel channel estimation scheme for such a system in Rician fading channels. First, the possible angle of arrivals (AOAs) of users served by a base station (BS) are derived by exploiting the channel statistical information, assuming a traditional pilot structure, where the pi...","Title: A New Framework of Filter Bank Multi-Carrier: Getting Rid of Subband Orthogonality.\nYear: 2017\n\nAbstract: Filter bank multi-carrier (FBMC) entitles many advantages over orthogonal frequency division multiplexing (OFDM) and is considered to be a more competitive waveform in the future generation cellular communications. In current FBMC, the prototype filter is deliberately designed to meet the perfect reconstruction (PR) constraint to establish subband orthogonality in real domain, which may not be opt...","Title: Frequency-Domain Intergroup Interference Coordination for V2V Communications.\nYear: 2017\n\nAbstract: With the development of vehicle-to-vehicle (V2V) communications, the interference among different V2V communication groups will become the limitation for high-rate transmissions. Two intergroup interference coordination schemes are proposed for the V2V communication. The first proposed scheme is a Doppler-shift-based frequency-domain interference alignment scheme. Through pre- and postprocessing, ...","Title: Near-Optimum Sparse Channel Estimation Based on Least Squares and Approximate Message Passing.\nYear: 2017\n\nAbstract: Accurately estimating the sparse channel with sequential under-sampled received signal is a challenging problem in broadband wireless communication systems, especially when prior knowledge of the sparsity level and the probability distribution of the sparse channel is unavailable. A joint least-squares (LS) and approximate-message-passing (AMP) algorithm based on sparse Bayesian learning (SBL) model, named LS-AMP-SBL, is proposed to approach the optimal performance given by Oracle-LS, where Oracle-LS requires exact knowledge of the support of the sparse channel. The proposed algorithm has three steps. First, AMP-SBL estimates the sparse channel iteratively until convergence. Then, based on the coarse estimated channel of the first step and an adaptable threshold derived from the effective noise level, the support of the sparse channel can be detected with a high probability. The third step is to estimate the sparse channel using LS with the estimated support from the second step. By introducing a proper and adaptable threshold based on AMP-SBL operation, the proposed scheme is capable of accurately detecting the support of the spare channel, and thus achieves a near-optimal performance but with a much lower complexity than both simultaneous orthogonal matching pursuit and basic pursuit. Simulation results demonstrate that the proposed LS-AMP-SBL can approach the performance bound given by Oracle-LS.","Title: A Novel 3-D Massive MIMO Channel Model for Vehicle-to-Vehicle Communication Environments.\nYear: 2018\n\nAbstract: This paper presents 3-D vehicle massive multiple-input multiple-output (MIMO) antenna array model for vehicle-to-vehicle (V2V) communication environments. A spherical wavefront is assumed in the proposed model instead of the plane wavefront assumption used in the conventional MIMO channel model. Using the proposed V2V channel model, we first derive the closed-form expressions for the joint and mar...","Title: Joint Estimation of Frequency Offset and Doppler Shift in High Mobility Environments Based on Orthogonal Angle Domain Subspace Projection.\nYear: 2018\n\nAbstract: Conventional frequency preshift technology cannot distinguish between the large Doppler shift and the frequency offset aroused by crystal oscillator, which significantly hinders the system performance improvement in high mobility environments when the frequency offset is present. In this paper, a joint frequency offset and Doppler shift estimation algorithm in high mobility environment based on orthogonal angle domain subspace projection is proposed, which can track the fast time-varying Doppler shift and separate the Doppler shift from the frequency offset. First, an orthogonal angle domain subspace projection algorithm is proposed to project the Doppler spread caused by high mobility into equivalent Doppler shifts in each orthogonal subspace. Second, it utilizes equivalent Doppler shift of all orthogonal subspaces to jointly estimate the maximal Doppler shift and frequency offset. Finally, the estimates are used to compensate the frequency error in the received signal. Moreover, the maximum Doppler shift estimation, together with the projection vectors and the received power on each orthogonal subspace, is fed back and exploited in the subsequent transmitted signal. Simulation results show that the proposed method can estimate the two parameters accurately and eliminate almost all the errors on the Doppler rapidly changing area when SNR is up to 15 dB. Compared with the conventional receiver with automatic frequency control, the receiver with our proposed method achieves better system performance even on the Doppler rapidly changing area.","Title: Residual-Based Detections and Unified Architecture for Massive MIMO Uplink.\nYear: 2018\n\nAbstract: Massive multiple-input multiple-output (M-MIMO) technique brings better energy efficiency and coverage but higher computational complexity than small-scale MIMO. For linear detections such as minimum mean square error (MMSE), prohibitive complexity lies in solving large-scale linear equations. For a better trade-off between bit-error-rate (BER) performance and computational complexity, iterative linear algorithms like conjugate gradient (CG) have been applied and have shown their feasibility in recent years. In this paper, residual-based detection (RBD) algorithms are proposed for M-MIMO detection, including minimal residual (MINRES) algorithm, generalized minimal residual (GMRES) algorithm, and conjugate residual (CR) algorithm. RBD algorithms focus on the minimization of residual norm per iteration, whereas most existing algorithms focus on the approximation of exact signal. Numerical results have shown that, for 64-QAM 128 × 8 MIMO, RBD algorithms are only 0.13 dB away from the exact matrix inversion method when BER= 10− 4. Stability of RBD algorithms has also been verified in various correlation conditions. Complexity comparison has shown that, CR algorithm require 87% less complexity than the traditional method for 128 × 60 MIMO. The unified hardware architecture is proposed with flexibility, which guarantees a low-complexity implementation for a family of RBD M-MIMO detectors.","Title: On the Low-Complexity, Hardware-Friendly Tridiagonal Matrix Inversion for Correlated Massive MIMO Systems.\nYear: 2018\n\nAbstract: In massive multiple-input and multiple-output (M-MIMO) systems, one of the key challenges in the implementation is the large-scale matrix inversion operation, as widely used in channel estimation, equalization, detection, and decoding procedures. Traditionally, to handle this complexity issue, several low-complexity matrix inversion approximation methods have been proposed, including the classic Cholesky decomposition and the Neumann series expansion (NSE). However, the conventional approaches failed to exploit neither the special structure of channel matrices nor the critical issues in the hardware implementation, which results in poorer throughput performance and longer processing delay. In this paper, by targeting at the correlated M-MIMO systems, we propose a modified NSE based on tridiagonal matrix inversion approximation (TMA) to accommodate the complexity as well as the performance issue in the conventional hardware implementation, and analyze the corresponding approximation errors. Meanwhile, we investigate the very-large-scale integration implementation for the proposed detection algorithm based on a Xilinx Virtex-7 XC7VX690T FPGA platform. It is shown that for correlated massive MIMO systems, it can achieve near minimum mean square error performance and 630 Mb/s throughput. Compared with other benchmark systems, the proposed pipelined TMA detector can get high throughput-to-hardware ratio. Finally, we also propose a fast iteration structure for further research.","Title: Molecular Computing For Markov Chains\nYear: 2018\n\nAbstract: In this paper, it is presented a methodology for implementing arbitrarily constructed time-homogenous Markov chains with biochemical systems. Not only discrete but also continuous-time Markov chains are allowed to be computed. By employing chemical reaction networks as a programmable language, molecular concentrations serve to denote both input and output values. One reaction network is elaborately designed for each chain. The evolution of species' concentrations over time well matches the transient solutions of the target continuous-time Markov chain, while equilibrium concentrations can indicate the steady state probabilities. Additionally, second-order Markov chains are considered for implementation, with bimolecular reactions rather than unary ones. An original scheme is put forward to compile unimolecular systems to DNA strand displacement reactions for the sake of future physical implementations. Deterministic, stochastic and DNA simulations are provided to enhance correctness, validity and feasibility.","Title: Efficient Sparse Code Multiple Access Decoder Based on Deterministic Message Passing Algorithm.\nYear: 2018\n\nAbstract: Being an effective non-orthogonal multiple access (NOMA) technique, sparse code multiple access (SCMA) is promising for future wireless communication. Compared with orthogonal techniques, SCMA enjoys higher overloading tolerance and lower complexity because of its sparsity. In this paper, based on deterministic message passing algorithm (DMPA), algorithmic simplifications such as domain changing and probability approximation are applied for SCMA decoding. Early termination, adaptive decoding, and initial noise reduction are also employed for faster convergence and better performance. Numerical results show that the proposed optimizations benefit both decoding complexity and speed. Furthermore, efficient hardware architectures based on folding and retiming are proposed. VLSI implementation is also given in this paper. Comparison with the state-of-the-art have shown the proposed decoderu0027s advantages in both latency and throughput (multi-Gbps).","Title: Efficient Soft-Output Gauss-Seidel Data Detector for Massive MIMO Systems.\nYear: 2018\n\nAbstract: For massive multiple-input multiple-output (MIMO) systems, linear minimum mean-square error (MMSE) detection has been shown to achieve near-optimal performance but suffers from excessively high complexity due to the large-scale matrix inversion. Being matrix inversion free, detection algorithms based on the Gauss-Seidel (GS) method have been proved more efficient than conventional Neumann series expansion (NSE) based ones. In this paper, an efficient GS-based soft-output data detector for massive MIMO and a corresponding VLSI architecture are proposed. To accelerate the convergence of the GS method, a new initial solution is proposed. Several optimizations on the VLSI architecture level are proposed to further reduce the processing latency and area. Our reference implementation results on a Xilinx Virtex-7 XC7VX690T FPGA for a 128 base-station antenna and 8 user massive MIMO system show that our GS-based data detector achieves a throughput of 732 Mb/s with close-to-MMSE error-rate performance. Our implementation results demonstrate that the proposed solution has advantages over existing designs in terms of complexity and efficiency, especially under challenging propagation conditions.","Title: Improving Massive MIMO Belief Propagation Detector with Deep Neural Network.\nYear: 2018\n\nAbstract: In this paper, deep neural network (DNN) is utilized to improve the belief propagation (BP) detection for massive multiple-input multiple-output (MIMO) systems. A neural network architecture suitable for detection task is firstly introduced by unfolding BP algorithms. DNN MIMO detectors are then proposed based on two modified BP detectors, damped BP and max-sum BP. The correction factors in these algorithms are optimized through deep learning techniques, aiming at improved detection performance. Numerical results are presented to demonstrate the performance of the DNN detectors in comparison with various BP modifications. The neural network is trained once and can be used for multiple online detections. The results show that, compared to other state-of-the-art detectors, the DNN detectors can achieve lower bit error rate (BER) with improved robustness against various antenna configurations and channel conditions at the same level of complexity.","Title: Molecular Synthesis for Probability Theory and Stochastic Process\nYear: 2018\n\nAbstract: It is common that probability theory and stochastic process, especially Markov chains, have long been used to study and explain the behaviors of (CRNs). Nonetheless, this paper sees things from a reverse angle, devoting itself in synthesizing common probability theory and stochastic process with CRNs. The main motivation is to imitate and explore the evolution of large-scale and complex practical systems based on CRNs, by making use of the inherent parallelism and randomness. In our conference paper, a preliminary but concise approach has been put forward to synthesize the stand-alone examples such as law of total probability, Bayes’ theorem, and -step transition of Markov chains. To make this methodology systematic and theoretically sound, we enrich and offer more solid foundation for the previous version. Rigorous stability analysis based on (ODEs) are provided. This paper further deeply discusses and distinguishes building stochastic models for CRNs and utilizing CRNs to solve stochastic problems. A joint distribution of Markov chains are implemented using molecular reactions as a showcase. In order to enhance the clearness of the results, all the simulations are done according to deterministic mass action. It is worth noting that an already mathematically proven conclusion, which states that nearly an arbitrary set of bimolecular or unimolecular reactions can be implemented by DNA strand displacement reactions, ensures the meaningfulness of our work. It is also believed that, though in its infancy, the proposed approach is also valid for other molecular synthesis than DNA, as long as the kinetics constraints are met.","Title: Adaptive Preconditioned Iterative Linear Detection and Architecture for Massive MU-MIMO Uplink\nYear: 2018\n\nAbstract: Being the enabling technique for 5G wireless communications, massive multiple-input multiple-output (MIMO) system can drastically increase the capacity efficiency. However, a few hundreds of antennas will inevitably introduce notable complexity and therefore hinders its direct adoption. Though the state-of-the-art (SOA) iterative methods such as conjugate gradient (CG) detection show complexity advantage over the conventional ones such as MMSE detection, their convergence rates slow down if the antenna configurations become more complicated. To this end, first this paper devotes itself in exploring the convergence properties of iterative linear solvers and then leverages the proposed adaptive precondition technique to improve the convergence rate. This adaptive precondition technique is general and has been incorporated with steepest descent (SD) detection as a show case. An approximated calculation for log-likelihood ratios (LLRs) is proposed for further complexity reduction. Analytical and numerical results have shown that with the same iteration number, the adaptive preconditioned SD (APSD) detector outperforms the CG one around 1 dB when BER = 10. Hardware architecture for the APSD detector is proposed based on iteration bound analysis and architectural optimization for the first time. Architectures for other adaptive preconditioned iterative linear detectors can be easily derived by following similar design flow. Compared with the SOA designs, FPGA implementations have verified the APSD detector’s advantage in balancing throughput and complexity, and guaranteed its application feasibility for 5G wireless.","Title: Three-Dimensional Geometry-Based UAV-MIMO Channel Modeling for A2G Communication Environments.\nYear: 2018\n\nAbstract: We propose a 3-D elliptic-cylinder unmanned aerial vehicle (UAV) multiple-input-multiple-output (MIMO) channel model for air-to-ground communication environments. The mobility and altitude of UAV transmitters in the elevation plane are studied based on the proposed UAV-MIMO channel model. Furthermore, ground surface and roadside environment reflections are considered to investigate the statistical...","Title: A Non-Stationary Geometry-Based Scattering Vehicle-to-Vehicle MIMO Channel Model.\nYear: 2018\n\nAbstract: In this study, a non-wide-sense stationary geometry-based model that includes both static and mobile scatterers for vehicle-to-vehicle multiple-input multiple-output Ricean fading channels is presented. The proposed channel introduces a two-circle model to describe static vehicles (i.e., around the mobile transmitter (MT) and mobile receiver (MR)) and an ellipse model to depict stationary roadside...","Title: A Generalized Data Representation for Deep Learning-Based Communications Systems.\nYear: 2018\n\nAbstract: Deep learning (DL)-based autoencoder is a potential architecture to implement end-to-end communication systems. In this letter, we first give a brief introduction to the autoencoder-represented communication system. Then, we propose a novel generalized data representation (GDR) aiming to improve the data rate of DL-based communication systems. Finally, simulation results show that the proposed GDR scheme has lower training complexity, comparable block error rate performance and higher channel capacity than the conventional one-hot vector scheme. Furthermore, we investigate the effect of signal-to-noise ratio (SNR) in DL-based communication systems and prove that training at a high SNR could produce a good training performance for autoencoder.","Title: An Advanced Receiver for Universal Filtered Multicarrier.\nYear: 2018\n\nAbstract: In this correspondence paper, we propose an advanced receiver for universal filtered multicarrier (UFMC) to improve its performance. For the conventional receiver of UFMC, the even subcarriers are used to decode the source data while the odd subcarriers are considered containing interferences and discarded. In this paper, we show that the odd subcarriers also contain useful information of the tran...","Title: Novel 3-D Irregular-Shaped Geometry-Based Channel Modeling for Semi-Ellipsoid Vehicle-to-Vehicle Scattering Environments.\nYear: 2018\n\nAbstract: This letter presents a 3-D irregular-shaped geometry-based stochastic model for vehicle-to-vehicle (V2V) radio propagation environments, in which an asymmetric directional multiple input and multiple output technique is employed at the mobile transmitter (MT). The time-varying geometric path lengths are introduced in the proposed channel model to capture the non-stationarity, which is caused by th...","Title: Synthesizing a Neuron Using Chemical Reactions\nYear: 2018\n\nAbstract: Deep learning and synthetic biology are two highly popular fields and draw lots of attentions. Deep learning has been employed for complex problems, and researchers have developed synthetic biology into a powerful tool for More than Moore. However, few works have considered implementing deep neural networks (DNNs) with synthetic biology. In this paper, by revealing the common probability base, we aim to implement the most fundamental element of DNN, a neuron, using chemical reaction networks (CRNs). We firstly propose a computation model in CRNs, then present our architecture of a neuron using such computation model as a basis. The correctness of such computation model and architecture is proved by both mathematical derivation and silico simulation.","Title: A Low-Complexity Massive MIMO Detection Algorithm Based on Matrix Partition\nYear: 2018\n\nAbstract: In this paper, a low-complexity Massive MIMO uplink detection algorithm based on matrix partition is introduced. The proposed block diagonal with multiple-level iterations (BD-MLI) is suitable for both single and multiple-antenna user equipments (UEs) systems and shows robust bit-error-rate (BER) performance in poor propagation environments such as correlated channel and small antenna configuration ratio. Specifically, BD-MLI achieves BER = 10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">4</sup>\nat signal-to-noise ratio (SNR) of 14 dB and 16 dB in non-ideal propagation environment in single and multiple-antenna UEs system, respectively. It outperforms conventional matrix partition (MP) method by 47% complexity reduction and consistent near MMSE detection performance. Also, an efficient VLSI architecture is designed for the proposed BD-MLI algorithm.","Title: Massive MIMO Detection based on Barzilai-Borwein Algorithm\nYear: 2018\n\nAbstract: For a massive multiple-input multiple-output (MI-MO) system, how to cope with the detection difficulties brought by increasing antennas is intractable. Linear methods such as zero-forcing (ZF) and minimum mean square error (MMSE) can achieve sub-optimal performance while suffer from high complexity because of large-scale matrix inversion. Recently, some iterative detectors such as steepest descent (SD) and conjugate gradient (CG) have been proposed to balance the complexity and performance. However, their fast convergence would not maintain when the system loading factor increases. To address the aforementioned issues, this paper 1) introduces a new iterative algorithm called Barzilai-Borwein (BB) that outperforms SD with inexpensive operations and 2) proposes its improved form entitled SDBB to accelerate the convergence even in bad conditions. Both theoretical and numerical results have demonstrated its advantages over the state-of-the-art ones. More specifically, SDBB can surpass the existing split pre-conditioned conjugate gradient (SPCG) detector by more than 2 dB at the bit error rate (BER) of 10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">3</sup>\n when the number of users is relatively large, and reach a complexity reduction of 10%.","Title: A Novel D-Metric for Blind Detection of Polar Codes\nYear: 2018\n\nAbstract: As a known error-correcting code that has been proved to fully achieve the binary discrete memoryless channel (B-DMC) capacity, polar codes have been considered as a breakthrough in coding theory since its invention. In 2016, polar codes were selected by the 3GPP as the control channel codes for the enhance mobile broadband (eMBB) scenario. The related research of polar codes has been further pushed to the forefront of applications. In spite of the urgent practical needs, research on the algorithm design and efficient implementation of polar codes for control channels and Internet of Things (IoT) is still in infancy. This paper is to combine successful cancellation (SC) and simplified successful cancellation (SSC) decoders to propose a low-complexity algorithm that can realize blind detection of polar codes. Log-likelihood ratios (LLRs) of frozen bits are used to introduce a new metric D, which is to distinguish polar codes of different formats. The realization of blind detection of polar codes can avoid the receiver's executing complicated decoding algorithm for all polar code candidates, reducing the power, complexity, and delay.","Title: Efficient Compressed Landweber Detector for Massive MIMO\nYear: 2018\n\nAbstract: Massive multiple-input multiple-output (M-MIMO) provides better efficiency and coverage than conventional MIMO. Efficient detector, being indispensable for M-MIMO, is the focus of nowadays research. For M-MIMO, MMSE detector with exact matrix inversion works well but suffers from complexity, not to mention the performance degradation in ill-posed cases. Thus, Landweber detector (LD) and improved Landweber detector (ILD) are considered. In this paper, the compressed Landweber detector (CLD) is proposed with much lower complexity but the same performance as ILD. Numerical results show that for 128×8 MIMO with 64-QAM, CLD approximates MMSE detector with lower complexity. When BER = 10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">4</sup>\n, the gap is only 0:24 dB with 2 iterations. When antenna configuration is 128×60, CLD can achieve 82% complexity reduction than ILD. Unified hardware architecture of ILD is proposed. Folding is considered for further reduction. With the same hardware as ILD, architecture of CLD is finally proposed.","Title: Expectation Propagation Detection with Neumann-Series Approximation for Massive MIMO\nYear: 2018\n\nAbstract: For massive multiple-input multiple-output (MIMO) systems, signal detection is always a key concern. Traditional detection methods such as minimum mean square error (MMSE) all suffer from a variety of problems in respect of complexity and performance when applied to large-scale MIMO systems. In this paper, expectation propagation (EP) algorithm is employed to guarantee high-accuracy and low-complexity of symbol detection in high-dimensional MIMO systems. Nevertheless, in the iterative updating process of EP algorithm, the inevitable matrix inversion operation is one of the key challenges to the realistic hardware implementation. Therefore, a new improved EP, which is termed as expectation propagation with Neumann-series approximation (EP-NSA), is firstly proposed to accommodate the complexity as well as the performance by executing an approximate matrix inversion with a small number of Neumann-series terms. Simulation results have shown that the proposed EP-NSA with two items achieves notable performance improvement compared to belief propagation (BP) detection when the system loading factor is relatively large. For antenna configurations with large loading factor, this approach achieves similar performance to MMSE while keeping lower computational complexity.","Title: Arithmetic Computations Based on Chemical Reaction Networks\nYear: 2018\n\nAbstract: Widely used as formalism for the analysis of chemical and biochemical systems, chemical reaction networks (CRNs) have received increasing attention as a fundamental model for molecular computation. This paper demonstrates that, with a new method, CRNs can compute most arithmetic computations (e.g., non-polynomial functions). By applying Taylor's Theorem and a finite-state machine (FSM) topology for arithmetic computations, the synthesis flow of accomplishing arithmetic computations is achieved. Since probability transmitted between designed FSMs can be naturally mapped to the concentration of molecular in solution, the whole computing process can be realized with molecular reactions instead of silicon-based hardware design. Theoretical analysis and numerical simulations have demonstrated the feasibility of the proposed approach.","Title: LDPC Decoder Based on Markov Chain Monte Carlo Method\nYear: 2018\n\nAbstract: Low-density parity check (LDPC) codes have attracted the attention of a large number of researchers with its near-Shannon performance and easy implementation features. As a data coding scheme under the 5G scenario, how to achieve efficient encoding/decoding for LDPC codes has become one of the important research topics. Under this condition, this paper 1) proposes a novel decoding algorithm for LDPC codes using the Markov Chain Monte Carlo (MCMC) method and 2) introduces two improved versions, MCMC-S and MCMC-L, which achieve better results. Simulation figures show that the improved methods outperform the traditional belief propagation (BP) decoding method in relatively short codes by more than 1 dB at the bit error rate (BER) of 10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">-3</sup>\n. Very large scale integration (VLSI) architecture of the proposed method is also given in this paper.","Title: A New Error Correction Scheme for Physical Unclonable Function\nYear: 2018\n\nAbstract: Error correction is an indispensable component when physical unclonable functions (PUFs) are used in cryptographic applications, because environmental factors influence PUFs' performance. Nowadays, syndrome-based scheme and code-offset scheme are used in PUF error correction. In this paper, a new scheme named error correction with multiple challenge-response pairs (ECMC) is proposed to perform better than code-offset scheme under certain circumstances.","Title: A Low-Complexity Codebook Design for Large-Scale SCMA\nYear: 2018\n\nAbstract: Sparse-code multiple-access (SCMA) is an effective non-orthogonal multiple-access (NOMA) technique, which ranks one of the most promising candidates for future wireless. However, most of the existing work prefer a low-connectivity SCMA system because of the difficulties in designing proper codebook, which limits its priorities for massive connection. In this paper, we propose a systematic, low-complexity codebook design for large-scale SCMA. Stage-based generation with quadrature amplitude modulation (QAM) is adopted in the codebook design for SCMA system with arbitrary parameters, where the layer operator of each user is fixed as constellation rotation for simplification. Extension from known codebook is another proposed design manner, which allocates the known codeword repetitively based on specific allocation order. With a effectiveness metric, numerical results reveal advantages of our work. Hardware architecture of the detector is also proposed in this paper.","Title: Adaptive Damped Jacobi Detector and Architecture for Massive MIMO Uplink\nYear: 2018\n\nAbstract: For massive multiple-input multiple-output (MIMO) detection, minimum mean square error (MMSE) method can achieve close-to-optimal performance. However, its computational complexity is proportional to the third power of antenna elements due to the inevitable matrix inversion operation. Especially when the number of transmitting antennas is very large, exact MMSE detection method becomes disabled owing to the excessive complexity. In this paper, an adaptive damped Jacobi (DJ) method is proposed firstly to iteratively realize MMSE performance without the intractable matrix inversion. By automatically updating the optimal relaxation factor w with the increase of iterations, the adaptive scheme does not require careful selection of initial relaxation factor compared to the conventional fixed-w DJ method. Simulation results have shown that the proposed adaptive DJ is more applicable to the correlated MIMO channels for its great flexibility of relaxation factor ω. Additionally, the hardware architecture design is also presented in this paper.","Title: An Adjustable Hybrid SC-BP Polar Decoder\nYear: 2018\n\nAbstract: Polar codes have drawn lots of attentions for the capacity-achieving property and low encoding/decoding complexity. As two promising decoding algorithms, successive cancellation (SC) decoding shows better performance but limited by high latency. Otherwise, belief Propagation (BP) algorithm presents high throughput yet with performance degradation. In this paper, a hybrid decoding architecture combining SC and BP decoding is proposed, which could process both algorithms in unified module within one decoding step. The simulation result reflects a tradeoff between decoding latency and performance with different decomposition levels. In terms of hardware implementation, the adjustable architecture is implemented based on systolic BP decoder and look-ahead SC decoder. The hybrid decoder offers the flexibility and generality which could apply on different conditions.","Title: Polar-coded forward error correction for MLC NAND flash memory.\nYear: 2018\n\nAbstract: With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell (MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code (ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate (FER) and decoding latency. Three decoders namely binary-input, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft log-likelihood ratio (LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared with LDPC codes. The stepwise maximum mutual information (SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared with other alternatives. Hardware architectures are also given in this paper.","Title: Optical Mobile Communications: Principles, Implementation, and Performance Analysis.\nYear: 2019\n\nAbstract: Owing to the rapid growth of mobile data communication and spectrum crunch at lower radio frequency, utilizing high frequency spectrum such as millimeter wave for ultra-high data rate mobile communications becomes necessary. Yet the propagation behaviors of high frequency radio waves make mobile communications rather challenging with a lot of technical problems, such as very large propagation loss...","Title: Low-Complexity Winograd Convolution Architecture Based on Stochastic Computing.\nYear: 2018\n\nAbstract: Deep convolution neural networks (CNNs) usually require a large number of iterative convolution operations, which would consume significant amounts of hardware resources. In this paper, we propose an efficient convolution architecture based on Winograd algorithm for convolutional neural networks (CNNs), by employing stochastic computing (SC). For the first step, a fast convolution algorithm, Winograd fast convolution algorithm (WFCA), which can lower the complexity by reducing multiplications is proposed. Although stochastic computing (SC) can achieve significant reduction in hardware complexity compared with the deterministic design, its straightforward application to fast convolution is not well-suited due to the precision loss. Therefore, based on two-line SC, this paper proposes a non-scaled stochastic adder which has higher computation accuracy than the conventional stochastic adder. Numerical results have proved the advantages of the proposed design in both complexity and precision. Although preliminary, it is expected that this design can be the first step of combining neural network and stochastic computing, which are both analog, belief-based and fault-tolerant, thereby unlocking the potentiality for the widespread application of stochastic Winograd algorithm in neural network systems.","Title: Quantum Algorithm for Spectral Regression for Regularized Subspace Learning.\nYear: 2019\n\nAbstract: In this paper, we propose an efficient quantum algorithm for spectral regression which is a dimensionality reduction framework based on the regression and spectral graph analysis. The quantum algorithm involves two core subroutines: the quantum principal eigenvectors analysis and the quantum ridge regression algorithm. The quantum principal eigenvectors analysis can be performed by an efficient sparse Hamiltonian simulation. For the ridge regression, we propose a quantum algorithm that is derived from the quantum singular value decomposition method. Our quantum ridge regression algorithm is more suitable for data matrices that are non-sparse and skewed. Our analysis demonstrates that the quantum subroutines can be implemented with an approximatively polynomial speedup on a quantum computer over their classical counterparts.","Title: Data-Rate Driven Transmission Strategy for Deep Learning Based Communication Systems.\nYear: 2018\n\nAbstract: Deep learning (DL) based autoencoder is a promising architecture to implement end-to-end communication systems. In this paper, we focus on the fundamental problems of DL-based communication systems, including high rate transmission and performance analysis. To address the limited data rate issue, we first consider the error rate constraint and design a transmission algorithm to adaptively select the transmission vectors to maximize the data rate for various channel scenarios. Furthermore, a novel generalized data representation (GDR) scheme is proposed to improve the data rate of DL-based communication systems. Then, we analyze the effect of signal-to-noise ratio (SNR) and mean squared error performance of the proposed DL-based communication systems. Finally, numerical results show that the proposed adaptive transmission and GDR schemes achieve higher data rate and have lower training complexity than the conventional one-hot vector scheme. Both the new schemes and the conventional scheme have comparable block error rate (BLER) performance. According to both theoretical analysis and simulated results, it is suggested that low or wide-range training SNR is beneficial to attain good BLER performance for practical transmission with various channel scenarios.","Title: Wide-range Dimmable Clipped Flip-OFDM For Indoor Visible Light Communications\nYear: 2018\n\nAbstract: Combination of illumination and communication is a key characteristic of visible light communications. Different environments require different illumination levels. When the desired dimming level is relatively low or high, conventional optical orthogonal frequency division multiplexing (O-OFDM) will suffer severe performance deterioration due to the clipping noise. This paper proposes a novel O-OFDM scheme named clipped flip-OFDM for indoor visible light communication systems with dimming control. In the proposed clipped flip-OFDM scheme, we design a new OFDM frame structure to keep the clipped information. We can achieve different dimming levels by adjusting the values of the direct-current (DC) bias and a control factor. Furthermore, the performance of the proposed clipped flip-OFDM scheme is less affected by the dimming level. Simulation results verify that the proposed clipped flip-OFDM achieves a wide dimming range, and the achievable spectral efficiency is stable.","Title: LOW-COMPLEXITY MESSAGE PASSING MIMO DETECTION ALGORITHM WITH DEEP NEURAL NETWORK\nYear: 2018\n\nAbstract: The channel hardening-exploiting message passing detection (MPD) algorithm achieves good performance in large-scale multiple-input multiple-output (MIMO) systems. However, for not-so-large systems with larger loading factors, the MPD suffers slow convergence rate and higher complexity. In this paper, a deep neural network (DNN)-aided message passing detector, DNN-MPD, is proposed. A modified MPD algorithm is firstly presented to compensate the approximation error in MPD, aiming at accelerating the convergence and attaining better performance. The DNN-MPD is then constructed by unfolding the modified MPD, and deep learning techniques are utilized to optimize the modification factors. Numerical results are presented to demonstrate the performance of the DNN-MPD compared with the original MPD. Through one training, the DNN-MPD can be used for multiple online detections, and it reaches faster convergence rate, outperforming the original MPD in the bit error rate (BER) performance in MIMO systems with large loading factors.","Title: An improvement for ad hoc on-demand routing protocol.\nYear: 2003\n\nAbstract: The two well-known on-demand protocols for ad hoc networks - DSR and AODV show degraded performance with traffic load increase. In this paper, we propose a traffic-balanced scheme, called TB scheme, to solve this problem. The TB scheme adapts MAC layer information for routing decisions. It avoids involving heavy loaded nodes in a new route and thus balances network traffic. Simulation results show that the new scheme significantly improves DSR and AODV's performance under heavy load conditions. © 2003 IEEE.","Title: A Large-Scale Extension of Sparse-Code Multiple-Access System.\nYear: 2018\n\nAbstract: Sparse-code multiple-access (SCMA) is an effective non-orthogonal multiple-access (NOMA) technique, which ranks one of the most promising candidates for future wireless, because of its outstanding performance. However, most of the existing work prefers low-connectivity SCMA systems, which actually cannot ful fi ll their priorities for massive connection. The dif fi culties in designing suitable factor graph matrix are responsible for this situation. In this paper, we propose a design manner of factor graph matrix to realize SCMA with large-scale customers. Quasi-cyclic property with shifting is introduced in SCMA factor graph matrix, based on the rules and restrictions of SCMA design including the column weight and the overloading factor. For numerical analysis, we introduce a performance function to show the effectiveness of our proposed SCMA system, and the results reveal that our work are better than conventional ones.","Title: Adaptive Modulation and Filter Configuration in Universal Filtered Multi-Carrier Systems.\nYear: 2018\n\nAbstract: Universal filtered multi-carrier (UFMC) is a potential waveform technology, which can efficiently combat different carrier frequency offsets (CFOs) of multiple users. First, adaptive modulation and power allocation are applied for each subcarrier to meet a preset bit error rate (BER) requirement by ignoring CFOs. Then, we prove that different CFOs will cause different interference variances to adj...","Title: Downlink Precoding with Correlation-Based User Grouping for Multiuser MISO Systems.\nYear: 2017\n\nAbstract: Correlation across transmit antennas in multiple-input single-output (MISO) broadcast channel has been studied to be detrimental generally. The current downlink beamforming schemes have not considered correlation enough such that they are not suitable for the broadcast systems with high correlation among transmit antennas. We propose two novel user grouping precoders to improve the sum rate performance for the case of ill-conditioned channel and the case of small transmit antennas (i.e., the number of transmit antennas is less than that of users). The first proposed precoder partitions all the users into small groups step by step based on the condition number. Downlink beamforming is then done in a small size for the optimal channel submatrix with smaller condition number. Inter-group interference from the subsequent allocated groups is nulled out in the null spaces of the previous allocated groups. The second precoder regularizes the number of users in the first group to improve the sum rate further. Simulation results verify that our schemes outperform the current beamforming schemes for the case of high transmit correlation. Moreover, the proposed precoders allow to be applied for the case of small antennas.","Title: Polar-Coded Forward Error Correction for MLC NAND Flash Memory Polar FEC for NAND Flash Memory.\nYear: 2018\n\nAbstract: With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell (MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code (ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate (FER) and decoding latency. Three decoders namely binary-input, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft log-likelihood ratio (LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared to LDPC codes. The stepwise maximum mutual information (SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared to other alternatives. Hardware architectures are also given in this paper.","Title: A Novel Estimated Wideband Geometry-Based Vehicle-to-Vehicle Channel Model Using an AoD and AoA Estimation Algorithm.\nYear: 2019\n\nAbstract: In this paper, we propose an estimated wideband geometry-based channel model for vehicleto-vehicle (V2V) communication environments, which is based on an angle of departure (AoD) and angle of arrival (AoA) estimation algorithm, to determine the ellipse scattering region and to efficiently study the V2V channel characteristics for different propagation delays, i.e., per-tap channel statistics. In the first stage, we estimate the AoD and AoA for the first tap. In this case, the ellipse-scattering region for the first tap can be determined. Then, we estimate the ellipse channel models for other taps based on the estimated model parameters for the first tap. Furthermore, the spatial cross-correlation functions (CCFs) are derived and thoroughly investigated for different propagation delays. The excellent agreement is achieved between the proposed channel statistics and prior results and measurements.","Title: Novel Channel Quality Indicator Prediction Scheme for Adaptive Modulation and Coding in High Mobility Environments.\nYear: 2019\n\nAbstract: In this paper, a novel channel quality indicator (CQI) prediction scheme for adaptive modulation and coding in high-speed mobility environments is proposed, where the wavenumber spectrum segmentation filters' bank is utilized to improve the estimation accuracy of channel prediction algorithm by enhancing the correlation of wireless channels in each orthogonal subspace. In the proposed method, the channel estimation, channel prediction, and signal-to-noise-rate (SNR) prediction are processed on the orthogonal subspace level, which can significantly decrease the mismatch level of the feedback CQI under the fast time-varying channels. Based on the predicted SNR after subspace signal combination, the effective SNR is obtained and is utilized to calculate the feedback CQI parameter. The autocorrelation function and spatial fading rate are analyzed with different feedback delays, which show that our proposed scheme provides stronger correlation of channels with the order of wavenumber spectrum segmentation filters' bank increasing. The simulation results show that the proposed scheme can achieve better throughput performance even with larger feedback delay in high-speed mobility environments.","Title: Three-Dimensional Non-Stationary Wideband Geometry-Based UAV Channel Model for A2G Communication Environments.\nYear: 2019\n\nAbstract: In this paper, we propose a novel three-dimensional multiple-input multiple-output channel model to describe the air-to-ground (A2G) communication environments. The model introduces the unmanned aerial vehicle (UAV) transmitter and ground mobile receiver (MR) located at the foci points of the boundary ellipsoid, while different ellipsoids represent the propagation properties for different time delays. In light of this, we are able to investigate the propagation properties of the A2G channel model for different time delays. Furthermore, the time-varying parameters of the azimuth angle of departure, the elevation angle of departure, the azimuth angle of arrival, and elevation angle of arrival are derived to properly describe the channel non-stationarity, which is caused by the motion of the UAV transmitter, cluster, and MR. The impacts of the movement properties of the cluster in both the azimuth and elevation planes are investigated on the channel characteristics, i.e., spatial cross-correlation functions, temporal autocorrelation functions, Doppler power spectrum density, and power delay profiles.","Title: Molecular Polar Belief Propagation Decoder and Successive Cancellation Decoder\nYear: 2019\n\nAbstract: Polar codes have been adopted for the enhanced mobile broadband control channels for the 5th communication system. By constructing chemical reaction networks (CRNs), this paper proposes a method of synthesizing polar belief propagation (BP) decoder and successive cancellation (SC) decoder. The proposed method is suitable for polar codes with arbitrary code length and code rate. Reactions in the proposed design could be experimentally implemented with deoxyribonucleic acid (DNA) strand displacement reactions, making the proposed polar decoders promising for wide application in nanoscale devices. Theoretical analysis and simulation results have validated the feasibility of this method.","Title: Sure-Tista: A Signal Recovery Network For Compressed Sensing\nYear: 2019\n\nAbstract: Deep neural network (DNN) has a wide range of applications in various fields, including solving sparse inverse problems. In this paper, we propose a novel network called the Stein's unbiased risk estimate based-trainable iterative thresholding algorithm (SURE-TISTA) for sparse signal recovery problems. Without prior information, SURE-TISTA outperforms TISTA, an algorithm based on the minimum mean squared error (MMSE) estimator. SURE-TISTA also shows a great robustness in many cases including large-scale and large-variance problems. Meanwhile, SURE-TISTA uses fewer learnable variables to achieve similar performance as learned approximate message passing (LAMP), which has more learnable parameters. Without any error measure estimator, SURE-TISTA achieves a near MMSE-based performance. Our numerical results indicate that SURE-TISTA is superior to TISTA and other traditional algorithms in many aspects, which can be promising in image denoising.","Title: Efficient Belief Propagation Detection Based On Channel Hardening For Massive Mimo\nYear: 2019\n\nAbstract: For massive multiple-input multiple-output (MIMO) detection, belief propagation (BP) based on graphical models has become a popular detection algorithm since it provides a good tradeoff between performance and complexity. To further lower the complexity of BP detection, an efficient BP detection based on channel hardening (BP-CH) is proposed. In this paper, the comparison in terms of both performance and complexity between proposed BP-CH and general BP is firstly investigated exhaustively. Simulation results have shown that the proposed BP-CH achieves similar performance behavior as general BP while keeping lower computational complexity. Additionally, an folded hardware architecture for proposed BP-CH detector is designed to improve the implementation efficiency. Meanwhile, VLSI implementation results have verified the great advantage of BP-CH regarding hardware overhead, especially for scenarios with large system loading factor.","Title: An Improved Software List Sphere Polar Decoder with Synchronous Determination\nYear: 2019\n\nAbstract: Being the first codes achieving the capacity of symmetric binary-input discrete memoryless channels, polar codes have been favorable and standardized for enhanced mobile broadband (eMBB) control channels. In future mobile communications, the entire system is required to be flexible and adaptive to varying scenarios. Therefore, efficient software implementation of polar decoder is expected. Existin...","Title: A Multicast Scheme Based on Fidelity Metrics in Quantum Networks.\nYear: 2019\n\nAbstract: A multicast scheme based on fidelity metrics in quantum networks is proposed in this paper. First of all, according to the fidelity of copies in an asymmetric mechanism of 1 -> 1 + 1 + 1 + 1 which is derived, the way of information transmission in the quantum networks is defined: one is one-to-one transmission based on the teleportation and the other is one-to-many lossy transmission based on quantum cloning mechanism. Second, in a specified quantum network which is a connected graph, a source node can randomly assign multicast group members. Then, with constraints of the number of replicas and the maximum number of hops of the shortest path, an optimal multicast tree is constructed to obtain maximum fidelity. Finally, the simulation results show that the proposed scheme can select the optimal path from the source node to the multicast members for the specified quantum network. With the increase of multicast group members, the average value of information fidelity obtained by all members decreases. Compared with the multicast tree constructed by the KMB algorithm, which is used to construct the Steiner tree in classical communication, the proposed schemes make the information fidelity obtained by multicast group members improve significantly.","Title: Optical Adaptive Antenna Array For Multiuser Mobile Optical Communication\nYear: 2019\n\nAbstract: In this paper, an optical adaptive antenna array system for multi-user optical mobile communication is studied. A coherent signal source is embedded in a spherical optical phased cell array with an external spherical lens system. The system can predict the signal power of the receiving end according to the channel transfer matrix and perform power compensation when transmitting the signal. Correspondingly, a pure phase lossless desired light field recovery algorithm is proposed and used for space division multiple access and free power allocation of antenna array systems. A small-scale optical adaptive antenna array experimental system is built and tested with good performance and consistent with the expected results.","Title: Joint spatial modulation and beamforming based on statistical channel state information for hybrid massive MIMO communication systems\nYear: 2019\n\nAbstract: Spatial modulation is a promising transmission scheme for massive multiple-input multiple-output (MIMO) systems to improve energy efficiency. In this study, considering the low-complexity hybrid structure, the authors propose a joint spatial modulation and beamforming scheme for a hybrid massive MIMO system in both single user and multi-user scenarios. Specifically, a design criterion of the channel control parameter is provided to reduce the high correlation among different channel coefficients in the hybrid massive MIMO system. In addition, with the statistical channel state information acquired at the base station, the optimum analogue beamforming vectors are designed with the goal of maximising the signal to leakage and noise ratio in the multi-user scenario. Furthermore, the upper bound, the lower bound as well as the closed form approximation of achievable spectral efficiency of the proposed scheme are derived for both single user and multi-user scenarios. Numerical simulation results demonstrate that the proposed scheme outperforms the conventional MIMO scheme.","Title: A 3-D Non-Stationary Wideband Geometry-Based Channel Model for MIMO Vehicle-to-Vehicle Communications in Tunnel Environments\nYear: 2019\n\nAbstract: In this paper, we present a three-dimensional (3-D) wideband geometry-based channel model for multiple-input and multiple-output vehicle-to-vehicle (V2V) communication in tunnel environments. We introduce a two-cylinder model to describe moving vehicles, as well as multiple confocal semi-ellipsoid models to depict internal surfaces of tunnel walls. The received signal is constructed as a sum of direct line-of-sight propagations, rays with single and double interactions. The movement between the mobile transmitter and mobile receiver results in time-varying geometric statistics that make our channel model non-stationary. Using this channel model, the proposed channel characteristics are studied for different V2V scenarios. The numerical results demonstrate that the proposed 3-D non-wide-sense stationary (WSS) wideband channel model is practical for characterizing real V2V channels.","Title: Outage Analysis and Beamwidth Optimization for Positioning-Assisted Beamforming\nYear: 2022\n\nAbstract: Beamforming based on channel estimation can be computationally intensive and inaccurate when the antenna array is large, while positioning information can reduce the complexity. In this work, we study the outage probability of positioning-assisted beamforming systems. Closed-form outage probability bounds are derived by considering positioning error, link distance and beamwidth. Based on the analytical result, we show that the beamwidth should be optimized with respect to the link distance and the transmit power, and such optimization significantly suppresses the outage probability.","Title: A Novel Method to Estimate the Coordinates of LEDs in Wireless Optical Positioning Systems\nYear: 2021\n\nAbstract: Traditional visible light positioning (VLP) systems estimate receivers' coordinates based on the known light-emitting diode (LED) coordinates. However, the LED coordinates are not always known accurately. Because of the structural changes of the buildings due to temperature, humidity or material aging, even measured by highly accurate laser range finders, the LED coordinates may change unpredictab...","Title: Improving Approximate Expectation Propagation Massive MIMO Detector With Deep Learning\nYear: 2021\n\nAbstract: In this letter, an efficient model-driven deep learning (DL) based massive multiple-input multiple-output (MIMO) detector is proposed by improving the approximate expectation propagation (EPA) algorithm, named EPANet. Specifically, EPANet is constructed by unfolding the iterative EPA detector and adding learnable parameters to enhance the performance and convergence robustness through the DL appro...","Title: Low-Complexity Construction of Polar Codes Based on Genetic Algorithm\nYear: 2021\n\nAbstract: How to efficiently rank the reliability order of the channels is critical for polar code construction. A new polar code construction framework tailored to a given decoding algorithm based on the genetic algorithm has been proposed to achieve an error correction performance gain. However, the time complexity of this scheme is extremely high. In this letter, a scheme based on a hash table is propose...","Title: Successive-Coded Spatial Shift Keying Modulation for MIMO Wireless Communications\nYear: 2021\n\nAbstract: Spatial domain modulation employs spatial degree of freedom to convey information bits. Traditional spatial domain modulation schemes include spatial modulation, spatial shift keying (SSK), and variations of these two schemes. To fully make use of the spatial degree of freedom and improve the achievable data rate of traditional spatial domain modulation schemes, we propose a successive-coded SSK (...","Title: Performance Analysis of Multi-Branch Reconfigurable Intelligent Surfaces-Assisted Optical Wireless Communication System in Environment With Obstacles\nYear: 2021\n\nAbstract: Since optical links are easily blocked by obstacles in the environment, they have been considered difficult to directly perform wireless communications. However, reconfigurable intelligent surfaces (RISs), as a new type of digital coding meta-materials, can significantly improve the coverage of optical communication by establishing new links. We propose a controllable multi-branch wireless optical...","Title: Hardware Implementation For Bipartite Belief Propagation Polar Decoding With Bit Flipping\nYear: 2021\n\nAbstract: For the scenarios with high throughput requirements, the belief propagation (BP) decoding is one of the most promising decoding strategies for polar codes. By pruning the redundant variable nodes (VNs) and check nodes (CNs) in the original factor graph, the graph is condensed to a sparse bipartite graph that is similar to the graph for low-density parity-check (LDPC) codes. In this paper, we introduce the bit flipping scheme into the LDPC-like BP (L-BP) decoding and propose two methods to identify the error-prone VNs. By additional decoding attempts, the L-BP flip (L-BPF) decoding improves the error-correction performance with a similar average complexity for high E-b/N-0 values. The simulation results show that the L-BPF decoding achieves 0.25 dB gain compared with the L-BP decoding. Finally, a parallel decoder with the proposed L-BPF algorithm for an (256,128) polar code is implemented using 65nm CMOS technology, and it delivers a throughput of 1877.3 Mbps.","Title: A Geometry-Based Stochastic Channel Model And Its Application For Intelligent Reflecting Surface Assisted Wireless Communication\nYear: 2021\n\nAbstract: Intelligent reflecting surface (IRS) is a new concept originating from metamaterials, which can achieve beamforming through controllable passive reflecting. This device makes it possible to engineer the wireless communication environment, and has drawn increasing attention. However, the associated channel models in current literature are mainly borrowed from conventional wireless channel models directly, omitting the unique features of IRS. In this paper, a geometry-based stochastic channel model for IRS-assisted wireless communication system is employed. The model has certain accuracy and low computational complexity. In particular, it captures the correlations of subchannels associated with different IRS elements, which is typically not considered in current works. Based on this channel model and the derived channel spatial correlation functions (CFs), an iterative reflection coefficients configuration method is proposed exploiting statistical channel state information to maximise the ergodic channel capacity. The impacts of the IRS spatial positions as well as the number of the IRS elements on the ergodic channel capacity is investigated through simulations. It is found that to obtain a larger ergodic channel capacity, the IRS should be placed in the vicinity of either the transmitter side or the receiver side, which is a useful guideline for practical deployment.","Title: Orbital Angular Momentum Multiplexing Communication System Over Atmospheric Turbulence With K-Best Detection\nYear: 2021\n\nAbstract: As the optical communication technology advances, vortex beam with orbital angular momentum (OAM) has gained wide attention due to its potential to significantly increase the channel capacity. Under the influence of atmospheric turbulence, there are still challenging problems in the OAM multiplexing system. To the best of our knowledge, in this paper one multiple-input-multiple-output (MIMO) detection technology named K-best detection, is first applied to the OAM multiplexing system. Numerical simulation results indicate the proposed solution enhances the performance of the optical communication system compared with data-aided least mean square (DA-LMS) and minimum mean squared error (MMSE) detection. Furthermore, with MMSE sorted QR decomposition (MMSE-SQRD) preprocessing, the performance of K-best detection can be further improved. When C, about 4.4 dB signal-to-noise ratio (SNR) gain can be obtained by preprocessing at k = 2 while the complexity is not significantly increased. Computational complexity is also analyzed in this paper, results show that K-best detection with winner path extension (WPE) algorithm can achieve 43% system complexity reduction, achieving a compromise between performance and complexity in K-best detection.","Title: Efficient Soft-Output Gauss–Seidel Data Detector for Massive MIMO Systems\nYear: 2021\n\nAbstract: For massive multiple-input multiple-output (MIMO) systems, linear minimum mean-square error (MMSE) detection has been shown to achieve near-optimal performance but suffers from excessively high complexity due to the large-scale matrix inversion. Being matrix inversion free, detection algorithms based on the Gauss–Seidel (GS) method have been proved more efficient ...","Title: Design of a Broadband Microwave Sampler Based on Step Recovery Diode\nYear: 2021\n\nAbstract: A new type of broadband microwave sampler is designed in this paper. It can work in 20–50 GHz. The circuit of microwave sampler has the following three parts, including the balun, pulse generator circuit and sampling diode circuit. In the pulse generator circuit, we only use the step recovery diode (SRD) to generate very narrow sampling pulse. Compared with the short circuit microstrip line pulse ...","Title: A 3D Stochastic Channel Model for 6G Wireless Double-IRS Cooperatively Assisted MIMO Communications\nYear: 2021\n\nAbstract: In this paper, we propose a three-dimensional (3D) stochastic channel model for double intelligent reflecting surface (IRS) cooperatively assisted multiple-input multiple-output (MI-MO) communications, where two distributed IRSs are respectively deployed near a mobile transmitter (MT) and a mobile receiver (MR). The double-IRS is distributed on the surface of buildings to assist the transmitter to...","Title: Location Aware Multi-cell MIMO Communications Assisted by Optical Positioning\nYear: 2021\n\nAbstract: This paper proposes a high-energy-efficiency location aware multi-cell multiple input multiple output (MIMO) communication system assisted by optical positioning. The location information acquisition method in the optical positioning subsystem has been designed, which can perform real-time angle of arrival and distance estimation for users and other scatterers and identify the users through the fe...","Title: Quantum algorithm for Laplacian eigenmap via Rayleigh quotient iteration\nYear: 2022\n\nAbstract: Laplacian eigenmap (LE) is a geometrically motivated algorithm for dimensionality reduction. However, as the data dimensionality increasing, it is intractable for classical computers to solve the generalized eigen-problem which is a crucial subroutine of the LE. In this work, we propose a quantum algorithm for Laplacian eigenmap (QLE). Compared with classical LE, our QLE can provide an exponential speedup in eigenmapping step over classical counterparts under some mild condition. In our scheme, we first present a quantum subroutine for adjacency graph construction based on the controlled SWAP test and maximum searching algorithm. Second, a variational quantum generalized eigensolver (VQGE) is proposed to solve the generalized eigen-problem Ax=lambda Bx. The proposed VQGE avoids the determination of the partial derivatives of the Rayleigh quotient and the difficulty of selecting hyperparameter. Finally, as a proof-of-principle, we conduct a numerical simulation to solve the variational quantum Laplacian eigenmap of randomly generated data points.","Title: Asymptotic Analysis of Diversity Receptions Over Correlated Lognormal-Rician Fading Channels\nYear: 2021\n\nAbstract: Lognormal-Kit:km random variables (RV) can model large-scale and small-scale fading, line-of-sight and non-line-of-sight channels in wireless communications. However, the versatile stochastic tool is mathematically intractable for correlated cases. In this work, we derive closed-form expressions for the outage probabilities of diversity receptions over dual-branch lognormal-Rician fading channels with arbitrary correlation at high signal-to-noise ratio (SNR). The analytical results show that the lognormal RV and the Rician RV, respectively, contribute an exponential factor and a fractional factor to the outage probability expressions. Some important insights are revealed based on the elegant expressions. For example, negative correlation between the lognormal RVs can suppress the outage probability, and the phase of the complex correlation coefficient between the accompanying Gaussian RVs in the Rician channels can significantly influence the performance.","Title: A Statistical MIMO Channel Model for Reconfigurable Intelligent Surface Assisted Wireless Communications\nYear: 2022\n\nAbstract: Reconfigurable intelligent surface (RIS) consisting of a large number of programmable near-passive units has been a hot topic in wireless communications due to its capability in providing smart radio environments to enhance the communication performance. However, the existing research are mainly based on simplistic channel models, which will, in principle, lead to inaccurate analysis of the system...","Title: Capacity Results for Range-Limited SISO and MISO Dimmable VLC Channels\nYear: 2022\n\nAbstract: This paper investigates the capacity results of dimmable visible light communications (VLCs) channel under practical range-limited constraints. Upper and lower bounds for both single-input single-output (SISO) and multiple-input single-output (MISO) scenarios which are valid in all signal-to-noise (SNR) region are derived. We reveal that the SISO capacity is a symmetrical function of the dimming t...","Title: Fast Iterative Soft-Output List Decoding of Polar Codes\nYear: 2022\n\nAbstract: Iterative detection and decoding (IDD) enjoys a higher capacity than separate detection and decoding (SDD). However, IDD requires both the detector and the decoder to support soft input and soft output. Considering the standard channel codes in 5G communication systems, the preferred decoder for polar codes, the successive cancellation list (SCL) decoder, outputs only hard decisions on the side of codeword. Yet, current soft-output polar decoders, such as belief propagation (BP) and soft cancellation (SCAN), are much inferior to the SCL decoders in terms of error correction performance. To this end, we propose a soft-output list (SOL) decoder in this paper, which considers both hypotheses of 0 and 1 for unreliable bits and keeps the \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">a-priori</i>\n likelihoods for reliable bits, so that it can provide soft output and satisfactory error-rate performance at the same time. Exploiting the property of special nodes, the resulting FastSOL decoder can directly return soft messages from these nodes, thus speeding up the decoding. The error-rate performance of the FastSOL decoder enhances as the number of iterations increases in the non-IDD setup. The proposed FastSOL decoder can also be applied in the IDD system. Concatenated with a maximum \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">a-posteriori</i>\n detector in ten IDD loops, our decoder with a list size of eight exhibits over 1 dB gain compared to using the SCAN decoder for polar codes with length 256 and half rate, which also outperforms the state-of-the-art soft list decoder by 0.12 dB in the same settings with a higher computational complexity, but comparable decoding latency.","Title: An Efficient Stochastic Convolution Architecture Based on Fast FIR Algorithm\nYear: 2022\n\nAbstract: By utilizing stochastic computing (SC), the hardware consumption of convolutional neural networks (CNNs) can be decreased significantly. However, long stream length is required to produce acceptable results, which leads to extended computation time. As a result, the inherent random fluctuation error and long latency of processing random bitstreams have made previous SC-CNN implementations ineffici...","Title: Efficient MMSE-PIC Detection for Polar-Coded System Using Tree-Structured Gray Codes\nYear: 2022\n\nAbstract: This letter proposes an iterative multiple-input multiple-output (MIMO) receiver for polar-coded system using minimum mean-square error parallel interference cancellation (MMSE-PIC) algorithm. And we propose a new kind of tree-structured Gray codes to reduce the computational complexity of MMSE-PIC without performance degradation. Simulation results indicate that, for a 64 \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\times $ </tex-math></inline-formula>\n 4 MIMO system, the iterative detection and decoding (IDD) scheme with different decoding algorithms outperforms the separate detection and decoding (SDD) scheme 0.35 ~ 0.58 dB at the frame error rate (FER) of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$10^{-3}$ </tex-math></inline-formula>\n when the number of iterations is four.","Title: Wireless Optical Positioning With Multiple Photodiodes and LED Clusters\nYear: 2022\n\nAbstract: Visible light positioning (VLP) systems provide higher accuracy and lower costs compared to their radio-frequency counterparts. Angle-of-arrival (AOA) based VLP systems are stable and accurate. However, existing AOA VLP systems with a photodiodes (PD) array usually require an unrotated receiver, densely placed LEDs, or auxiliary devices such as accelerometers and gyroscopes. In this paper, we develop an approach to exploit LED clusters and a PD array to locate the receiver. The new approach increases the angle-difference-of-arrival (ADOA) positioning accuracy and circumvents the rotation estimation in AOA positioning. More importantly, the method only requires the solution of linear equation sets, which is computationally efficient. Simulations show that the proposed positioning method can achieve an average mean error below 0.1 m within a 3 m × 3 m area.","Title: A 3D Non-Stationary MIMO Channel Model for Reconfigurable Intelligent Surface Auxiliary UAV-to-Ground mmWave Communications\nYear: 2022\n\nAbstract: Unmanned aerial vehicle (UAV) communications exploiting millimeter wave (mmWave) can satisfy the increasing data rate demands for future wireless networks owing to the line-of-sight (LoS) dominated transmission and flexibility. In reality, the LoS link can be easily and severely blocked due to poor propagation environments such as tall buildings or trees. To this end, we introduce a reconfigurable intelligent surface (RIS), which passively reflects signals with programmable reflection coefficients, between the transceivers to enhance the communication quality. Specifically, in this paper we generalize a three-dimensional (3D) non-stationary wideband end-to-end channel model for RIS auxiliary UAV-to-ground mmWave multiple-input multiple-output (MIMO) communication systems. By modeling the RIS as a virtual cluster, we study the \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">power delivering capability</i>\n of RIS as well as the \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">fading characteristic</i>\n of the proposed channel model. Important channel statistical properties are derived and thoroughly investigated, and the impact of RIS reflection phase configurations on these statistical properties is studied, which provides guidelines for the practical system design. The agreement between theoretical and simulated as well as measurement results validate the effectiveness of the proposed channel model.","Title: Approximate Message Passing for Channel Estimation in Reconfigurable Intelligent Surface Aided MIMO Multiuser Systems\nYear: 2022\n\nAbstract: Channel estimation is one of the main challenges for implementing reconfigurable intelligent surface (RIS)-aided communication system with a large number of antennas at the base station (BS) because RIS is equipped with many passive reflective elements without active transmitting/receiving and signal processing abilities. In this paper, we focus on the channel estimation in a general RIS-aided multi-user mmWave communication system. Specifically, a novel two-phase channel estimation scheme consisting of on-line and off-line phases is proposed to estimate the BS-RIS channel, RIS-user channel, and BS-user channel, respectively. Inspired by the characteristics of few scatterers in mmWave communication systems, the antenna domain channels are converted into the virtual angular domain channels by using the discrete Fourier transform (DFT) matrix. Thus, the estimation problem can be formulated as a compressed sensing (CS) problem, and solved by using efficient vector approximate message passing (VAMP) algorithm with expectation-maximization (EM) to learn unknown parameters and obtain the estimates simultaneously. Simulation results show that, the above algorithm with two choices of prior distributions in the proposed mmWave RIS-aided multi-user system has fast convergence speed and desirable estimation performance.","Title: Multi-User Successive-Coded Spatial Modulation Scheme Based on Beamforming\nYear: 2022\n\nAbstract: By combining an existing successive-coded spatial shift keying (SC-SSK) modulation scheme with a modulation scheme that uses the traditional constellation, we propose a new successive coded spatial modulation (SC-SM) scheme. This scheme uses spatial domain and constellation domain to jointly transmit information bits, which increases the achievable rate of the system. In order to extend the SC-SM scheme to multi-user scenario, a multi-user SC-SM (MU-SC-SM) scheme based on beamforming is proposed. The proposed MU-SC-SM scheme not only eliminates the inter-user interference (IUI) and enhances the received signal-to-noise ratio (SNR) of the served user, but also resolves the conflict between beamforming and spatial modulation. The achievable rate, the bit-error-rate (BER) performance and computational complexity of the proposed MU-SC-SM scheme are analyzed in detail. The impacts of the imperfect channel state information on the BER performance are also analyzed. Simulations are carried out to verify that the proposed MU-SC-SM scheme is superior to existing multi-user spatial modulation schemes in BER performance."],"string":"[\n \"Title: Adaptive primary user's signal detection algorithm based on matrix accumulation estimation for cognitive radio.\\nYear: 2011\\n\\nAbstract: In this article, a new adaptive primary user's signal detection algorithm for cognitive radio, which integrates frequency-domain block adaptive filtering with a matrix accumulation estimation, is presented with detailed description' of the concept and process of the algorithm. Then, the performance of the algorithm is analyzed and compared by simulation according to the practical requirement of cognitive radio. The result shows that the proposed detection algorithm can detect weak signals quickly and effectively with higher detection probability.\",\n \"Title: Router-Assisted Layered Multicast\\nYear: 2002\\n\\nAbstract: Several layered multicast protocols have been proposed for congestion control in real-time multicast applications. Most of them are pure end-to-end protocols, thus having difficulty In coordinating receivers and coping with traffic variations. In this paper, we propose RALM, a new receiver-driven router-assisted layered multicast protocol. RALM achieves much better performance at the expense of moderate additional complexity in the network. RALM is incrementally deployable. We evaluate RALM through simulations, and compare its performance with RLM, the well known layered multicast protocol.\",\n \"Title: On grouped OFDM-IDMA\\nYear: 2011\\n\\nAbstract: A generalized version of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) referred to as grouped OFDM-IDMA (G-OFDM-IDMA) is introduced in this paper. By dividing the users into several groups and transmitting each group's data only on part of the subcarriers, the G-OFDM-IDMA system is capable of having much lower decoding complexity compared with the conventional OFDM-IDMA while preserving the bandwidth efficiency and the bit error rate (BER) performance. We study the performance of the proposed scheme in terms of the decoding complexity and diversity order. We also extend the results to the multiple receive antennae case. Simulations are performed to corroborate the performance of the proposed G-OFDM-IDMA.\",\n \"Title: Modulation Scheme Based on Precoder Matrix for MIMO Optical Wireless Communication Systems.\\nYear: 2012\\n\\nAbstract: A modulation scheme for multiple-input multiple-output (MIMO) optical wireless systems that employ intensity modulation (IM) is proposed. This scheme, called precoder matrix modulation (PMM), exploits the properties of MIMO optical wireless communications to translate the spatial dimension into the constellation parameters by using a 'precoder matrix'. The transmitted signals in PMM are guaranteed to be nonnegative, as required in IM optical wireless communications. Existing schemes such as pulse-amplitude modulation could be used in such systems, but the proposed scheme has a much better performance. The constellation size of PMM can be flexibly increased, mitigating the bandwidth shortage issue due to the limitation of light emitting diodes (the transmitters). © 2012 IEEE.\",\n \"Title: Internet multicast routing and transport control protocols\\nYear: 2002\\n\\nAbstract: Multicasting is a mechanism to send data to multiple receivers in an efficient way. We give a comprehensive survey on network and transport layer issues of Internet multicast. We begin with an introduction to the current Internet protocol multicast model-the "host group" model and the current Internet multicast architecture, then discuss in depth the following three research areas: (1) scalable mu...\",\n \"Title: An Efficient Joint Timing And Frequency Offset Estimation For Ofdm Systems\\nYear: 2009\\n\\nAbstract: This paper presents a new joint frame synchronization and frequency offset estimation algorithm for orthogonal frequency division multiplexing (OFDM) systems as a modification to Zhang's method [1]. By designing a new training preamble weighted by PN sequence, the timing estimator is improved (at least 3dB with low SNR). By estimating time offset first, the computational load is greatly reduced with no loss in frequency offset estimation accuracy. The performance of the proposed method is evaluated by computer simulations in terms of timing error rate (TER) together with computational complexity.\",\n \"Title: OFDM-IDMA with User Grouping\\nYear: 2013\\n\\nAbstract: A generalized version of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) referred to as grouped OFDM-IDMA (G-OFDM-IDMA) is introduced in this paper. By dividing users into groups and transmitting each group's data only on some (as opposed to all) subcarriers, G-OFDM-IDMA can have much lower decoding complexity compared with conventional OFDM-IDMA while preserving the bit error probability (BEP) performance and the bandwidth efficiency. The user grouping problem is formulated into an integer linear programming problem whose suboptimal solution is proposed and compared with the lower bound. The optimization complexity issue is also addressed. Simulations are carried out to test the performance of G-OFDM-IDMA under various system configurations. It is observed that up to 80% complexity could be saved when the conventional OFDM-IDMA is substituted by G-OFDM-IDMA configured according to the suboptimal grouping solution.\",\n \"Title: Adaptive modulation with finite rate feedback for QR decomposition-successive interference cancellationbased multiple-in multiple-out systems\\nYear: 2013\\n\\nAbstract: This article studies adaptive modulation for QR decomposition and successive interference cancellation receivers in multiple-input multiple-output systems over slow- and fast-fading channels. In slowly fading channels, adaptive modulation schemes with finite-rate feedback under the constraints of a constant total transmit power, discrete-rate and a target bit-error-rate (BER) are proposed. Specifically, the authors first develop adaptive modulation with modulation order feedback only. For power allocation and modulation order feedback, the authors establish an optimisation scheme that can be solved easily and analyse the effect of power-level quantisation on the achievable data rates. For the fast fading channel case, the authors analyse the probability distribution of the `R' matrix and derive a scheme that only requires feedback of the statistical information of the channel for adaptive modulation with optimal bit loading to guarantee that the BER target is met.\",\n \"Title: Network-Supported Layered Multicast Transport Control for Streaming Media\\nYear: 2007\\n\\nAbstract: Multicast is very efficient in distributing a large volume of data to multiple receivers over the Internet. Layered multicast helps solve the heterogeneity problem in multicast delivery. Extensive work has been done in the area of layered multicast, for both congestion control and error control. In this paper, we focus on network-supported protocols for streaming media. Most of the existing work solves the congestion control and error control problems separately and does not give an integrated efficient solution. In this paper, after reviewing related work, we introduce our proposed protocols, namely, router-assisted layered multicast (RALM) and router-assisted layered FEC (RALF). The former is a congestion control protocol, whereas the latter is an error control protocol. They work under the same framework and provide an integrated solution. We also extend RALM to RALM-II, which is compatible with transmission control protocol (TCP) traffic. We analyze the complexity of the proposed protocols in the network and investigate their performance through simulations. We show that our solution achieves significant performance gains with reasonable additional complexity.\",\n \"Title: A joint channel estimation and synchronization algorithm for high speed digital IR-UWB system\\nYear: 2010\\n\\nAbstract: This letter proposes a joint channel estimation and synchronization algorithm for impulse radio ultra-wideband (IRUWB) communication. High-speed sampling and 1-bit quantization at the receiver are assumed to achieve high data rate with reasonable complexity. Simulation results show that the proposed algorithm works well when inter-symbol interference (ISI) is ignored during the preamble period.\",\n \"Title: Improved SNR Evolution for OFDM-IDMA Systems\\nYear: 2012\\n\\nAbstract: The bit error rate performance of interleave division multiple access (IDMA) based systems can be predicted by signal-to-noise ratio (SNR) evolution which tracks the average symbol SNR at each iteration and provides a faster solution than brute-force simulations. As the desired SNR in the evolution procedure is hard to obtain, approximate SNR updating formula has been widely adopted in the literature. In this paper a revised SNR updating formula is proposed for orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems in Rayleigh fading channels. Theoretical analysis shows that the new updating formula provides a tighter lower bound of the expected SNR in the evolution procedure compared with the existing one. We then verified this by simulations.\",\n \"Title: Symbol Detection of IDMA Systems in the Presence of Carrier Frequency Offsets\\nYear: 2013\\n\\nAbstract: In this paper we investigate the detection algorithms for interleave division multiple access (IDMA) systems in the presence of carrier frequency offsets (CFOs). The existing IDMA detection algorithm is designed under the zero CFO assumption and its performance will be degraded when the CFOs are present. We first extend the existing algorithm to the nonzero CFO case by utilizing effective channel coefficients which take the CFO effects into account. Then we turn to a more practical scenario with imperfect CFO estimates. We propose an algorithm that can cope with the residual CFO effects by integrating the CFO updating into the iterative receiver. Signal-to-interference-plus-noise ratio analysis and simulations show the feasibility and superiority of our proposed algorithms.\",\n \"Title: Mimo-Ofdm Visible Light Communications System With Low Complexity\\nYear: 2013\\n\\nAbstract: In visible light communication (VLC) systems with intensity modulation (IM) and direct detection (DD), the modulation bandwidth of light emitting diode (LED) is limited, and dispersion of the channel might cause inter-symbol interference. Also, the transmitted signal must be nonnegative. Thus most modulation schemes for radio communications cannot be used directly for such a system. This paper develops a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) VLC system that overcomes the modulation bandwidth limitation of LED and satisfies the requirements of the transmitted signal for IM/DD. Also, two transmit data streams require only one inverse discrete Fourier transform (IDFT) block, resulting in a low computational complexity. The transmitter architecture, receive algorithm, bit error rate performance, channel capacity analysis, and simulation results are provided.\",\n \"Title: A New View on Channel Capacity of MISO Frequency Selective Channels.\\nYear: 2011\\n\\nAbstract: A new view of multiple-input and single-output (MISO) technology in the frequency selective channels has been expressed in this letter. The definition of the virtual multiple receive antennas is proposed, which shows the maximum degree of freedom in the MISO frequency selective channel is more than one. Analytical and simulation results show that channel capacity can be improved by increasing the number of transmit antennas in the MISO frequency selective environment.\",\n \"Title: A Novel Receiver for ACO-OFDM in Visible Light Communication.\\nYear: 2013\\n\\nAbstract: This letter proposes a novel receiver for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) system in visible light communication to enhance its performance. In ACO-OFDM, the even subcarriers are distorted by the clipping noise and are simply discarded in the conventional receiver. In this letter we show that the signals on the even subcarriers can be viewed as data-dependent precoded OFDM. A novel receiver based on minimum mean square error criteria is then proposed to exploit the even subcarriers to collect additional diversity and coding gains, leading to improved bit error rate performance. Simulations show that the proposed receiver provides significant signal-to-noise ratio gain (up to 10 dB) over the conventional receiver, especially in non-line-of-sight channels. Moreover, the proposed receiver is also superior to some existing advanced ones. © 1997-2012 IEEE.\",\n \"Title: Two-level multicarrier UWB: A case study\\nYear: 2010\\n\\nAbstract: In our previous work we have proposed a new ultra-wideband (UWB) communication scheme referred to as two-level multicarrier (TLMC) UWB. TLMC UWB has some structurally inherited advantages compared to the conventional multiband orthogonal frequency division multiplexing UWB scheme, which make it a promising candidate for future ultra-high speed communications. However, in that work we presented the proposed scheme in a general manner. In this paper we study a specific type of TLMC UWB which is based on exponentially modulated filter banks. We will elaborate the system model and investigate the equalization task in detail. System performance is also evaluated through computer simulation.\",\n \"Title: A simulated method of modeling wireless channel based on CDL\\nYear: 2010\\n\\nAbstract: Rapid development of wireless communications gives prominence to simulation. Simulated methods of modeling wireless channel are of significance to wireless communications simulation on both link and system levels. There have been quite a lot of theoretical models which have accurately described the characteristics of wireless channel. However when it comes to the realization of wireless channel in simulation, there seem no accurate enough methods and conclusions. Current simulated methods are mostly built up based on TDL, which is a common framework to model micro fading and mainly focused on micro fading. As to macro fading, Doppler-effect and polarization of electromagnetic wave, this method behaves not well enough, and other statistical approximations is indispensable, such as shadow fading, Doppler power spectrum density and so on. To the question existed, this paper proposes a simulated method to accurately model wireless channel under given wireless environment, on the basis of cluster delay line. This method is highlighted with comprehensive consideration of macro and micro fading, Doppler, multi-path and polarization effect. Analysis and simulation results on characteristics of wireless channel such as signal envelope, coherent time and bandwidth, validate the proposed model. ©2010 IEEE.\",\n \"Title: Design of indoor optical wireless collaborative cellular system.\\nYear: 2011\\n\\nAbstract: In this paper, we propose a non-imaging method to implement the indoor optical wireless cellular system. Design of base stations and portable devices are presented and analyzed. Our design combining some collaborative schemes can improve SISO performance. Based on our proposed system, non-imaging MIMO techniques can perform properly at all receiver positions. © 2011 IEEE.\",\n \"Title: OFDM-IDMA communications over underwater acoustic channels\\nYear: 2011\\n\\nAbstract: The combination of orthogonal frequency division multiplexing (OFDM) and interleave division multiple access (IDMA), known as OFDM-IDMA, has been proposed as a promising multiple access scheme for wireless communications due to its low decoding complexity and potential of achieving high spectral efficiency. However, most of the work on OFDM-IDMA is in radio frequency (RF) communications scenarios and based on computer simulations. In this paper, we propose OFDM-IDMA over underwater acoustic (UWA) channels with experimental results. We also extend the original OFDM-IDMA to a multiple hydrophones scenario to improve the bit error rate (BER) performance. Experimental results show that with multiple hydrophones, the coded BER performance of OFDM-IDMA approaches zero after only a few iterations, validating the feasibility of our proposed approach over UWA channels.\",\n \"Title: Transmit Beamforming for MIMO Optical Wireless Communication Systems\\nYear: 2014\\n\\nAbstract: This paper focuses on transmit beamforming for multiple-input multiple-output optical wireless communication (OWC) systems with intensity modulation and direct detection (IM/DD). OWC with IM/DD requires the transmitted signals to be nonnegative, for which existing beamforming schemes developed for radio frequency systems cannot be applied directly. We propose effective schemes for OWC over frequency flat and frequency selective channels. For frequency flat fading, the property of the beamforming vector is derived. For frequency selective fading, bit-error rate performances of the proposed scheme with zero-forcing and minimum mean-square error frequency domain equalization receivers are derived, and a suboptimal beamforming vector for frequency selective fading channels is proposed. Compared with asymmetrically clipped optical orthogonal frequency division multiplexing based frequency domain beamforming, the proposed scheme needs much less feedback information and has a better error performance.\",\n \"Title: An Optimum DC-Biasing for DCO-OFDM System.\\nYear: 2014\\n\\nAbstract: Selecting an appropriate direct current (dc) bias is crucial to obtain positive and low-peak-to-average-power-ratio electrical signals in the dc optical orthogonal frequency-division multiplexing (DCO-OFDM) system. In this letter, our goal is to propose an optimization strategy of dc bias under given lower and upper clipping bounds. We characterize the mean square error between the original signals and the clipped ones as the metric of clipping distortion. Finding the optimum dc bias can be formulated as a nonconvex optimization problem. However, the optimum dc bias can be obtained from a numerical method. The simulation results show that the bit error ratio performance can be improved when employing the optimum dc bias obtained by the proposed numerical method.\",\n \"Title: Comparison of optical OFDM-IDMA and optical OFDMA for uplink visible light communications\\nYear: 2012\\n\\nAbstract: In this paper we compare two candidate multiple access schemes for visible light communications (VLC), namely, optical orthogonal frequency division multiplexing interleave division multiple access (O-OFDM-IDMA) and optical orthogonal frequency division multiple access (O-OFDMA). Both of them belong to multicarrier transmission schemes and are tailored for VLC channels by asymmetrically clipping at zero after OFDM modulation. We compare their bit error rate (BER) performance, receiver complexities as well as peak-to-average power ratios (PAPRs) in different scenarios. Simulations show that O-OFDM-IDMA is more power efficient than O-OFDMA, especially for higher throughput, at the cost of higher computational complexity. The PAPRs of O-OFDM-IDMA and O-OFDMA do not show much difference. Those results provide a useful guidance for the design of future networks based on VLC.\",\n \"Title: Optimal symmetric double-sided signal clipping in DCO-OFDM visible light communication\\nYear: 2014\\n\\nAbstract: In this paper, the optimal DC bias value of symmetric double-sided signal clipping in DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) visible light communication (VLC) system is deduced. Double-sided clipping is necessary due to the unipolarity of the optical intensity-modulated, direct-detected (IM/DD) system and power limit of the transmitter. Symmetric double-sided clipping is adopted to achieve wider dynamic range. Clipping noise is analyzed for system performance investigation. The optimal DC bias value is deduced by minimizing the system bit error ratio (BER) at given transmitter optical power. An equation of signal to noise ratio (SNR), signal energy, and optimal DC bias value is derived. Finally, the optimal algorithm is verified through a BER simulation at different DC bias values.\",\n \"Title: Lower bounds on the capacity for Poisson optical channel\\nYear: 2014\\n\\nAbstract: New reliable and accurate capacity bounds for Poisson channel modeled optical communication system are derived under peak-power and average-power constraints. The bounds are based on two entropy inequalities of Poisson random variables. Simulation results show that the proposed bounds are much tighter than previous ones, especially at lower signal-to-noise (SNR) region, where most wireless optical links typically operate.\",\n \"Title: A low complexity receiver for OFDM-IDMA with multiple carrier frequency offsets\\nYear: 2014\\n\\nAbstract: The performance of orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems would be severely degraded by the inter-carrier interference (ICI) which is caused by multiple carrier frequency offsets (CFOs). Existing receivers with CFO mitigation capabilities either have extremely high complexities or suffer from performance loss compared with the conventional receiver in the absence of CFOs. In this paper we propose a new receiver suitable for OFDM-IDMA in the presence of multiple CFOs. By properly performing soft interference cancellation (SIC) and variance approximation, the proposed receiver is capable of completely eliminating the CFO effects with a much lower complexity which is comparable with the zero CFO case. Both signal-to-interference-plus-noise ratio (SINR) and complexity analysis are conducted to theoretically validate the idea of the proposed receiver. Simulation results are also presented to compare the proposed receiver with existing ones. It is shown that the proposed receiver is a strong candidate for OFDM-IDMA with CFOs in practice.\",\n \"Title: SoftOC: Real-time projector-wall-camera communication system\\nYear: 2013\\n\\nAbstract: Camera-equipped consumer electronics tend to become cheaper and cheaper currently. These cameras can provide high-speed communication links to combat the shortage of radio spectrum. This paper introduces SoftOC, a novel real-time projector-wall-camera communication system. We name our system software optical communication (SOC) system. In order to improve the reliability of these systems and to speed up the computing process, we propose some schemes. We verify the effectiveness of our proposed schemes on real-time communication prototype.\",\n \"Title: DNA Computing for Combinational Logic.\\nYear: 2018\\n\\nAbstract: With the progressive scale-down of semiconductor’s feature size, people are looking forward to More Moore and More than Moore. In order to offer a possible alternative implementation process, researchers are trying to figure out a feasible transfer from silicon to molecular computing. Such transfer lies on bio-based modules programming with computer-like logic, aiming at realizing the Turing machine. To accomplish this, the DNA-based combinational logic is inevitably the first step we have taken care of. This timely overview study introduces combinational logic synthesized in DNA computing from both analog and digital perspectives separately. State-of-the-art research progress is summarized for interested readers to quick understand DNA computing, initiate discussion on existing techniques and inspire innovation solutions. We hope this study can pave the way for the future DNA computing synthesis.\",\n \"Title: Data rate optimization in inter-cell interference environment of visible light communication\\nYear: 2016\\n\\nAbstract: Abstract This paper investigates the higher-order modulation using Hadamard matrix to improve the data rate performance, particularly in the interference regions of a multi-cell environment in visible light communication. It presents a novel scheme which utilizes Hadamard matrix to produce orthogonal pulses (OPs) that mitigate the inter-cell interference, and covers the interference areas of the room for mobile receivers. The minimum power requirements is examined to achieve optimum data rate in whole area of the room. Moreover, the signal-to-noise ratio is derived to provide the similar capacity distribution between cells. Theoretical analysis and simulation experiments of bit error rate (BER) and capacity performances are conducted and three arrangements of signals in cells are compared, which are defined as all cells use different sets of OPs (DSOPs), all cells use the same set of OPs (SSOPs) and reuse OPs in diagonal (ROPD) cells of the room. The results show that the BER performance of DSOPs is \\\\(10^{-2.7}\\\\) at the high interference area, which is the best performance compared to ROPD and SSOPs. Moreover, DSOPs requires less power to achieve 2, 3 and 4 bits/symbol compared to ROPD and SSOPs.\",\n \"Title: DC and non-DC biased optical filter bank multicarrier communication for IM/DD channel\\nYear: 2016\\n\\nAbstract: This paper proposes two filter bank multicarrier (FBMC) schemes for optical communication in intensity modulation direct detection (IM/DD) channel with and without direct current (DC) bias. The aim is to overcome some inherent drawbacks of the commonly used optical orthogonal frequency division multiplexing (OFDM) schemes. Key transceiver principles are designed to accommodate the requirements of IM/DD channel. Various performance metrics are analyzed and compared with optical OFDM schemes. It is found that the proposed schemes are more spectral and power efficient than their optical OFDM counterparts. In addition, the DC-biased optical FBMC scheme fully supports asynchronized multiuser uplink transmission, which is another pronounced advantage over the optical OFDM schemes that require stringent synchronization to maintain orthogonality. The analysis is confirmed by simulations. The findings may shed light into potential research line on FBMC based IM/DD optical communications.\",\n \"Title: A New Framework for Non-orthogonal Multiple Access Based on Generalized Energy Spreading Transform.\\nYear: 2016\\n\\nAbstract: With the increasing needs of high data rate communication, spectrally more efficient communication schemes are desired. In multiuser communication context, conventional orthogonal multiple access (OMA) schemes suffer from spectral efficiency loss by fundamental information theoretics. Non-orthogonal multiple access (NOMA) schemes are more appropriate. In this paper, we propose a new NOMA system based on generalized energy spreading transform (GEST). We give the basic system structure and compare it with some existing NOMA systems. It is interesting that the proposed GEST-MA can be viewed as a generalization of several existing NOMA systems. Analysis and simulations show that GEST-MA is more flexible than current NOMA systems and is capable of achieving the potential diversity gain without sacrificing the spectral efficiency. Those properties make it a strong candidate for the next generation mobile communication systems.\",\n \"Title: Properties and achievable data rate of a cyclic prefix based imperfect reconstruction filter bank multiple access system.\\nYear: 2016\\n\\nAbstract: In this study, the authors propose a cyclic prefix (CP) based imperfect reconstruction (IPR) filter bank multicarrier (FBMC) system in the uplink of multiuser networks, known as filter bank multiple access (FBMA). The prototype filter in the system is a common low-pass filter without any perfect reconstruction (PR) or nearly perfect reconstruction (NPR) constraint. CP appended input signal format ...\",\n \"Title: Subcarrier-wise power allocation for OFDM-IDMA systems\\nYear: 2015\\n\\nAbstract: Current orthogonal frequency division multiplexing interleave division multiple access (OFDM-IDMA) systems only employ the power optimization process in the user-wise level but the subcarrier-wise level remains untouched. This paper proposes a novel and efficient algorithm for subcarrier-wise power allocation in OFDM-IDMA system, which aims at maximizing the channel capacity under the constraints of user-wise average powers. Different from the widely used channel capacity formula, the objective function is changed from capacity of Gaussian inputs to capacity of quadrature phase shift keying (QPSK) modulated inputs. Comparisons with other alternative algorithms such as equal power allocation algorithm and water filling power allocation algorithm are provided. Simulation results show that the proposed algorithm can achieve better and more robust BER performance.\",\n \"Title: Upper bounds on the capacity for optical intensity channels with AWGN.\\nYear: 2017\\n\\nAbstract: The channel capacity of the optical wireless communication (OWC) systems is still a problem that has not an optimal and close-form expression, in spite of OWC can be used to achieve high data rates. This paper presents novel upper bounds on the channel capacity of an optical intensity modulated and directed detection (IM/DD) system under peak-power and average-power constraints. The channel is modeled as an additive white Gaussian noise (AWGN) optical channel. The bounds are derived based on sphere-based signal space argument. Simulation results show the proposed bounds are tight at both high and low signal-to-noise ratios (SNRs). Compared to those reported bounds, the derived bounds are better at high SNRs region in particular, and the expressions are simpler and unique for the whole range of average-to-peak-power ratio.\",\n \"Title: Blind Interference Alignment in Two-Cell Z Interference MIMO Channel.\\nYear: 2017\\n\\nAbstract: This paper proposes a blind interference alignment (BIA) scheme in two-cell Z interference multiple-input multiple-output channel where the cell edge user equipment (UE) of the first cell is interfered by the base station of the second cell during downlink transmissions, while the UE of the second cell is free from inter-cell interference. By employing the reconfigurable antennas at receivers, the transmit strategy of the proposed scheme is designed. The achievable degree of freedom (DoF), the achievable rates, and the bit error rate performance of the proposed BIA scheme are analyzed. Simulation results show that the achievable DoF and the throughput of the proposed scheme are improved compared with conventional interference control scheme. Furthermore, in the proposed BIA scheme, all UEs can achieve a good diversity gain to combat fading.\",\n \"Title: Blind Interference Alignment for Multiuser MISO Indoor Visible Light Communications.\\nYear: 2017\\n\\nAbstract: A filter-pair-based blind interference alignment scheme is proposed to improve the achievable degree of freedom (DoF) in multiuser multiple-input single-output indoor visible light communications. In the proposed scheme, the transmitter does not need to know channel state information. Different transmit sub-channels employ different pulse-shaping filters, and each user is equipped with multiple receive filters. The transmitter sends signals according to the predesigned strategy, and each user sets the receive mode by choosing the corresponding receive filter. Optical orthogonal frequency division multiplexing is employed in the proposed scheme to combat the intersymbol interference in high-speed transmissions, and the maximum achievable spectrum efficiency (SE) of the proposed scheme is analyzed. Simulation results validate that the proposed scheme can achieve higher SE and more DoF than the orthogonal multiple access schemes.\",\n \"Title: Approximate Message Passing-Based Joint User Activity and Data Detection for NOMA.\\nYear: 2017\\n\\nAbstract: This letter focuses on joint user activity and data detection in the uplink grant-free non-orthogonal multiple access systems based on approximate message passing (AMP) and expectation maximization (EM) algorithms. The proposed Joint-EM-AMP detection algorithm consists of three steps in each iteration. First, AMP decouples the superimposed received signal into uncoupled scalar problems. Then, at t...\",\n \"Title: Analysis of Geometric Multibounced Virtual Scattering Channel Model for Dense Urban Street Environments.\\nYear: 2017\\n\\nAbstract: This paper presents a generalized visual scattering channel model for car-to-car (C2C) mobile radio environments, in which an asymmetric directional antenna is deployed at the mobile transmitter (MT). The signals received at the mobile receiver (MR) from the MT are assumed to experience multibounced propagation paths. More importantly, the proposed model first separates the multibounced propagatio...\",\n \"Title: Optical mobile communications: Principles and challenges\\nYear: 2017\\n\\nAbstract: Optical wireless communication (OWC) is position sensitive and deemed not suitable for ultra-high throughput mobile communications. In this paper, we propose an optical mobile communication (OMC) system, which dynamically allocates optical beams to mobile users and tracks the users adaptively, thus extends OWC to mobile scenarios. Principles of OMC is introduced and several key design problems are discussed.\",\n \"Title: Enhanced time-shifted pilot based channel estimation in massive MIMO systems with finite number of antennas\\nYear: 2017\\n\\nAbstract: Time-shifted pilot scheme can efficiency combat pilot contamination. However, when the number of base station (BS) antennas is finite, the pilot interference due to the downlink transmission symbols cannot be mitigated in the time-shifted scheme. This paper proposed a novel two-stage channel estimation algorithm based on time-shifted pilot to reduce the effect of pilot interference. In the first stage, beamforming vectors are determined to reduce the interference from other cells by introducing null symbol periods. Then, receive beamforming is carried out. In the second stage, channel estimation is performed. In the proposed scheme, the pilots of different users in the same cell are orthogonal and the pilots are reused in other cells. The proposed scheme can reduce the effect of pilot interference and improve spectrum efficiency, when the number of BS antennas is finite. The proposed channel estimation algorithm is presented in detail, and the channel estimation performance and achievable spectrum efficiency are analyzed. Simulation results validate the proposed scheme.\",\n \"Title: Expectation-Propagation Based Low-Complexity Channel Estimation For Massive Mimo Systems\\nYear: 2017\\n\\nAbstract: In this paper we propose a low-computational-complexity channel estimation algorithm for the downlink of massive MIMO systems. This algorithm employs the expectation propagation and expectation maximization techniques, assuming a sparsity promoting conditional Gaussian prior distribution on the channels. Its computational complexity scales only linearly with the number of transmit antennas, the number of pilots, and the channel length. Compared with existing state-of-the-art algorithms, it has a lower pilot overhead and is much more computationally efficient. The channel estimation mean-squared errors with the proposed algorithm and the existing block iterative support detection (block-ISD) and basic pursuit (BP) methods are simulated and compared. Results show that the performance of the proposed algorithm approaches the benchmark performance, and is significantly better than that of block-ISD and BP.\",\n \"Title: Channel Estimation for Multicell Multiuser Massive MIMO Uplink Over Rician Fading Channels.\\nYear: 2017\\n\\nAbstract: Pilot contamination (PC) is a major problem in massive multiple-input multiple-output (MIMO) systems. This paper proposes a novel channel estimation scheme for such a system in Rician fading channels. First, the possible angle of arrivals (AOAs) of users served by a base station (BS) are derived by exploiting the channel statistical information, assuming a traditional pilot structure, where the pi...\",\n \"Title: A New Framework of Filter Bank Multi-Carrier: Getting Rid of Subband Orthogonality.\\nYear: 2017\\n\\nAbstract: Filter bank multi-carrier (FBMC) entitles many advantages over orthogonal frequency division multiplexing (OFDM) and is considered to be a more competitive waveform in the future generation cellular communications. In current FBMC, the prototype filter is deliberately designed to meet the perfect reconstruction (PR) constraint to establish subband orthogonality in real domain, which may not be opt...\",\n \"Title: Frequency-Domain Intergroup Interference Coordination for V2V Communications.\\nYear: 2017\\n\\nAbstract: With the development of vehicle-to-vehicle (V2V) communications, the interference among different V2V communication groups will become the limitation for high-rate transmissions. Two intergroup interference coordination schemes are proposed for the V2V communication. The first proposed scheme is a Doppler-shift-based frequency-domain interference alignment scheme. Through pre- and postprocessing, ...\",\n \"Title: Near-Optimum Sparse Channel Estimation Based on Least Squares and Approximate Message Passing.\\nYear: 2017\\n\\nAbstract: Accurately estimating the sparse channel with sequential under-sampled received signal is a challenging problem in broadband wireless communication systems, especially when prior knowledge of the sparsity level and the probability distribution of the sparse channel is unavailable. A joint least-squares (LS) and approximate-message-passing (AMP) algorithm based on sparse Bayesian learning (SBL) model, named LS-AMP-SBL, is proposed to approach the optimal performance given by Oracle-LS, where Oracle-LS requires exact knowledge of the support of the sparse channel. The proposed algorithm has three steps. First, AMP-SBL estimates the sparse channel iteratively until convergence. Then, based on the coarse estimated channel of the first step and an adaptable threshold derived from the effective noise level, the support of the sparse channel can be detected with a high probability. The third step is to estimate the sparse channel using LS with the estimated support from the second step. By introducing a proper and adaptable threshold based on AMP-SBL operation, the proposed scheme is capable of accurately detecting the support of the spare channel, and thus achieves a near-optimal performance but with a much lower complexity than both simultaneous orthogonal matching pursuit and basic pursuit. Simulation results demonstrate that the proposed LS-AMP-SBL can approach the performance bound given by Oracle-LS.\",\n \"Title: A Novel 3-D Massive MIMO Channel Model for Vehicle-to-Vehicle Communication Environments.\\nYear: 2018\\n\\nAbstract: This paper presents 3-D vehicle massive multiple-input multiple-output (MIMO) antenna array model for vehicle-to-vehicle (V2V) communication environments. A spherical wavefront is assumed in the proposed model instead of the plane wavefront assumption used in the conventional MIMO channel model. Using the proposed V2V channel model, we first derive the closed-form expressions for the joint and mar...\",\n \"Title: Joint Estimation of Frequency Offset and Doppler Shift in High Mobility Environments Based on Orthogonal Angle Domain Subspace Projection.\\nYear: 2018\\n\\nAbstract: Conventional frequency preshift technology cannot distinguish between the large Doppler shift and the frequency offset aroused by crystal oscillator, which significantly hinders the system performance improvement in high mobility environments when the frequency offset is present. In this paper, a joint frequency offset and Doppler shift estimation algorithm in high mobility environment based on orthogonal angle domain subspace projection is proposed, which can track the fast time-varying Doppler shift and separate the Doppler shift from the frequency offset. First, an orthogonal angle domain subspace projection algorithm is proposed to project the Doppler spread caused by high mobility into equivalent Doppler shifts in each orthogonal subspace. Second, it utilizes equivalent Doppler shift of all orthogonal subspaces to jointly estimate the maximal Doppler shift and frequency offset. Finally, the estimates are used to compensate the frequency error in the received signal. Moreover, the maximum Doppler shift estimation, together with the projection vectors and the received power on each orthogonal subspace, is fed back and exploited in the subsequent transmitted signal. Simulation results show that the proposed method can estimate the two parameters accurately and eliminate almost all the errors on the Doppler rapidly changing area when SNR is up to 15 dB. Compared with the conventional receiver with automatic frequency control, the receiver with our proposed method achieves better system performance even on the Doppler rapidly changing area.\",\n \"Title: Residual-Based Detections and Unified Architecture for Massive MIMO Uplink.\\nYear: 2018\\n\\nAbstract: Massive multiple-input multiple-output (M-MIMO) technique brings better energy efficiency and coverage but higher computational complexity than small-scale MIMO. For linear detections such as minimum mean square error (MMSE), prohibitive complexity lies in solving large-scale linear equations. For a better trade-off between bit-error-rate (BER) performance and computational complexity, iterative linear algorithms like conjugate gradient (CG) have been applied and have shown their feasibility in recent years. In this paper, residual-based detection (RBD) algorithms are proposed for M-MIMO detection, including minimal residual (MINRES) algorithm, generalized minimal residual (GMRES) algorithm, and conjugate residual (CR) algorithm. RBD algorithms focus on the minimization of residual norm per iteration, whereas most existing algorithms focus on the approximation of exact signal. Numerical results have shown that, for 64-QAM 128 × 8 MIMO, RBD algorithms are only 0.13 dB away from the exact matrix inversion method when BER= 10− 4. Stability of RBD algorithms has also been verified in various correlation conditions. Complexity comparison has shown that, CR algorithm require 87% less complexity than the traditional method for 128 × 60 MIMO. The unified hardware architecture is proposed with flexibility, which guarantees a low-complexity implementation for a family of RBD M-MIMO detectors.\",\n \"Title: On the Low-Complexity, Hardware-Friendly Tridiagonal Matrix Inversion for Correlated Massive MIMO Systems.\\nYear: 2018\\n\\nAbstract: In massive multiple-input and multiple-output (M-MIMO) systems, one of the key challenges in the implementation is the large-scale matrix inversion operation, as widely used in channel estimation, equalization, detection, and decoding procedures. Traditionally, to handle this complexity issue, several low-complexity matrix inversion approximation methods have been proposed, including the classic Cholesky decomposition and the Neumann series expansion (NSE). However, the conventional approaches failed to exploit neither the special structure of channel matrices nor the critical issues in the hardware implementation, which results in poorer throughput performance and longer processing delay. In this paper, by targeting at the correlated M-MIMO systems, we propose a modified NSE based on tridiagonal matrix inversion approximation (TMA) to accommodate the complexity as well as the performance issue in the conventional hardware implementation, and analyze the corresponding approximation errors. Meanwhile, we investigate the very-large-scale integration implementation for the proposed detection algorithm based on a Xilinx Virtex-7 XC7VX690T FPGA platform. It is shown that for correlated massive MIMO systems, it can achieve near minimum mean square error performance and 630 Mb/s throughput. Compared with other benchmark systems, the proposed pipelined TMA detector can get high throughput-to-hardware ratio. Finally, we also propose a fast iteration structure for further research.\",\n \"Title: Molecular Computing For Markov Chains\\nYear: 2018\\n\\nAbstract: In this paper, it is presented a methodology for implementing arbitrarily constructed time-homogenous Markov chains with biochemical systems. Not only discrete but also continuous-time Markov chains are allowed to be computed. By employing chemical reaction networks as a programmable language, molecular concentrations serve to denote both input and output values. One reaction network is elaborately designed for each chain. The evolution of species' concentrations over time well matches the transient solutions of the target continuous-time Markov chain, while equilibrium concentrations can indicate the steady state probabilities. Additionally, second-order Markov chains are considered for implementation, with bimolecular reactions rather than unary ones. An original scheme is put forward to compile unimolecular systems to DNA strand displacement reactions for the sake of future physical implementations. Deterministic, stochastic and DNA simulations are provided to enhance correctness, validity and feasibility.\",\n \"Title: Efficient Sparse Code Multiple Access Decoder Based on Deterministic Message Passing Algorithm.\\nYear: 2018\\n\\nAbstract: Being an effective non-orthogonal multiple access (NOMA) technique, sparse code multiple access (SCMA) is promising for future wireless communication. Compared with orthogonal techniques, SCMA enjoys higher overloading tolerance and lower complexity because of its sparsity. In this paper, based on deterministic message passing algorithm (DMPA), algorithmic simplifications such as domain changing and probability approximation are applied for SCMA decoding. Early termination, adaptive decoding, and initial noise reduction are also employed for faster convergence and better performance. Numerical results show that the proposed optimizations benefit both decoding complexity and speed. Furthermore, efficient hardware architectures based on folding and retiming are proposed. VLSI implementation is also given in this paper. Comparison with the state-of-the-art have shown the proposed decoderu0027s advantages in both latency and throughput (multi-Gbps).\",\n \"Title: Efficient Soft-Output Gauss-Seidel Data Detector for Massive MIMO Systems.\\nYear: 2018\\n\\nAbstract: For massive multiple-input multiple-output (MIMO) systems, linear minimum mean-square error (MMSE) detection has been shown to achieve near-optimal performance but suffers from excessively high complexity due to the large-scale matrix inversion. Being matrix inversion free, detection algorithms based on the Gauss-Seidel (GS) method have been proved more efficient than conventional Neumann series expansion (NSE) based ones. In this paper, an efficient GS-based soft-output data detector for massive MIMO and a corresponding VLSI architecture are proposed. To accelerate the convergence of the GS method, a new initial solution is proposed. Several optimizations on the VLSI architecture level are proposed to further reduce the processing latency and area. Our reference implementation results on a Xilinx Virtex-7 XC7VX690T FPGA for a 128 base-station antenna and 8 user massive MIMO system show that our GS-based data detector achieves a throughput of 732 Mb/s with close-to-MMSE error-rate performance. Our implementation results demonstrate that the proposed solution has advantages over existing designs in terms of complexity and efficiency, especially under challenging propagation conditions.\",\n \"Title: Improving Massive MIMO Belief Propagation Detector with Deep Neural Network.\\nYear: 2018\\n\\nAbstract: In this paper, deep neural network (DNN) is utilized to improve the belief propagation (BP) detection for massive multiple-input multiple-output (MIMO) systems. A neural network architecture suitable for detection task is firstly introduced by unfolding BP algorithms. DNN MIMO detectors are then proposed based on two modified BP detectors, damped BP and max-sum BP. The correction factors in these algorithms are optimized through deep learning techniques, aiming at improved detection performance. Numerical results are presented to demonstrate the performance of the DNN detectors in comparison with various BP modifications. The neural network is trained once and can be used for multiple online detections. The results show that, compared to other state-of-the-art detectors, the DNN detectors can achieve lower bit error rate (BER) with improved robustness against various antenna configurations and channel conditions at the same level of complexity.\",\n \"Title: Molecular Synthesis for Probability Theory and Stochastic Process\\nYear: 2018\\n\\nAbstract: It is common that probability theory and stochastic process, especially Markov chains, have long been used to study and explain the behaviors of (CRNs). Nonetheless, this paper sees things from a reverse angle, devoting itself in synthesizing common probability theory and stochastic process with CRNs. The main motivation is to imitate and explore the evolution of large-scale and complex practical systems based on CRNs, by making use of the inherent parallelism and randomness. In our conference paper, a preliminary but concise approach has been put forward to synthesize the stand-alone examples such as law of total probability, Bayes’ theorem, and -step transition of Markov chains. To make this methodology systematic and theoretically sound, we enrich and offer more solid foundation for the previous version. Rigorous stability analysis based on (ODEs) are provided. This paper further deeply discusses and distinguishes building stochastic models for CRNs and utilizing CRNs to solve stochastic problems. A joint distribution of Markov chains are implemented using molecular reactions as a showcase. In order to enhance the clearness of the results, all the simulations are done according to deterministic mass action. It is worth noting that an already mathematically proven conclusion, which states that nearly an arbitrary set of bimolecular or unimolecular reactions can be implemented by DNA strand displacement reactions, ensures the meaningfulness of our work. It is also believed that, though in its infancy, the proposed approach is also valid for other molecular synthesis than DNA, as long as the kinetics constraints are met.\",\n \"Title: Adaptive Preconditioned Iterative Linear Detection and Architecture for Massive MU-MIMO Uplink\\nYear: 2018\\n\\nAbstract: Being the enabling technique for 5G wireless communications, massive multiple-input multiple-output (MIMO) system can drastically increase the capacity efficiency. However, a few hundreds of antennas will inevitably introduce notable complexity and therefore hinders its direct adoption. Though the state-of-the-art (SOA) iterative methods such as conjugate gradient (CG) detection show complexity advantage over the conventional ones such as MMSE detection, their convergence rates slow down if the antenna configurations become more complicated. To this end, first this paper devotes itself in exploring the convergence properties of iterative linear solvers and then leverages the proposed adaptive precondition technique to improve the convergence rate. This adaptive precondition technique is general and has been incorporated with steepest descent (SD) detection as a show case. An approximated calculation for log-likelihood ratios (LLRs) is proposed for further complexity reduction. Analytical and numerical results have shown that with the same iteration number, the adaptive preconditioned SD (APSD) detector outperforms the CG one around 1 dB when BER = 10. Hardware architecture for the APSD detector is proposed based on iteration bound analysis and architectural optimization for the first time. Architectures for other adaptive preconditioned iterative linear detectors can be easily derived by following similar design flow. Compared with the SOA designs, FPGA implementations have verified the APSD detector’s advantage in balancing throughput and complexity, and guaranteed its application feasibility for 5G wireless.\",\n \"Title: Three-Dimensional Geometry-Based UAV-MIMO Channel Modeling for A2G Communication Environments.\\nYear: 2018\\n\\nAbstract: We propose a 3-D elliptic-cylinder unmanned aerial vehicle (UAV) multiple-input-multiple-output (MIMO) channel model for air-to-ground communication environments. The mobility and altitude of UAV transmitters in the elevation plane are studied based on the proposed UAV-MIMO channel model. Furthermore, ground surface and roadside environment reflections are considered to investigate the statistical...\",\n \"Title: A Non-Stationary Geometry-Based Scattering Vehicle-to-Vehicle MIMO Channel Model.\\nYear: 2018\\n\\nAbstract: In this study, a non-wide-sense stationary geometry-based model that includes both static and mobile scatterers for vehicle-to-vehicle multiple-input multiple-output Ricean fading channels is presented. The proposed channel introduces a two-circle model to describe static vehicles (i.e., around the mobile transmitter (MT) and mobile receiver (MR)) and an ellipse model to depict stationary roadside...\",\n \"Title: A Generalized Data Representation for Deep Learning-Based Communications Systems.\\nYear: 2018\\n\\nAbstract: Deep learning (DL)-based autoencoder is a potential architecture to implement end-to-end communication systems. In this letter, we first give a brief introduction to the autoencoder-represented communication system. Then, we propose a novel generalized data representation (GDR) aiming to improve the data rate of DL-based communication systems. Finally, simulation results show that the proposed GDR scheme has lower training complexity, comparable block error rate performance and higher channel capacity than the conventional one-hot vector scheme. Furthermore, we investigate the effect of signal-to-noise ratio (SNR) in DL-based communication systems and prove that training at a high SNR could produce a good training performance for autoencoder.\",\n \"Title: An Advanced Receiver for Universal Filtered Multicarrier.\\nYear: 2018\\n\\nAbstract: In this correspondence paper, we propose an advanced receiver for universal filtered multicarrier (UFMC) to improve its performance. For the conventional receiver of UFMC, the even subcarriers are used to decode the source data while the odd subcarriers are considered containing interferences and discarded. In this paper, we show that the odd subcarriers also contain useful information of the tran...\",\n \"Title: Novel 3-D Irregular-Shaped Geometry-Based Channel Modeling for Semi-Ellipsoid Vehicle-to-Vehicle Scattering Environments.\\nYear: 2018\\n\\nAbstract: This letter presents a 3-D irregular-shaped geometry-based stochastic model for vehicle-to-vehicle (V2V) radio propagation environments, in which an asymmetric directional multiple input and multiple output technique is employed at the mobile transmitter (MT). The time-varying geometric path lengths are introduced in the proposed channel model to capture the non-stationarity, which is caused by th...\",\n \"Title: Synthesizing a Neuron Using Chemical Reactions\\nYear: 2018\\n\\nAbstract: Deep learning and synthetic biology are two highly popular fields and draw lots of attentions. Deep learning has been employed for complex problems, and researchers have developed synthetic biology into a powerful tool for More than Moore. However, few works have considered implementing deep neural networks (DNNs) with synthetic biology. In this paper, by revealing the common probability base, we aim to implement the most fundamental element of DNN, a neuron, using chemical reaction networks (CRNs). We firstly propose a computation model in CRNs, then present our architecture of a neuron using such computation model as a basis. The correctness of such computation model and architecture is proved by both mathematical derivation and silico simulation.\",\n \"Title: A Low-Complexity Massive MIMO Detection Algorithm Based on Matrix Partition\\nYear: 2018\\n\\nAbstract: In this paper, a low-complexity Massive MIMO uplink detection algorithm based on matrix partition is introduced. The proposed block diagonal with multiple-level iterations (BD-MLI) is suitable for both single and multiple-antenna user equipments (UEs) systems and shows robust bit-error-rate (BER) performance in poor propagation environments such as correlated channel and small antenna configuration ratio. Specifically, BD-MLI achieves BER = 10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">4</sup>\\nat signal-to-noise ratio (SNR) of 14 dB and 16 dB in non-ideal propagation environment in single and multiple-antenna UEs system, respectively. It outperforms conventional matrix partition (MP) method by 47% complexity reduction and consistent near MMSE detection performance. Also, an efficient VLSI architecture is designed for the proposed BD-MLI algorithm.\",\n \"Title: Massive MIMO Detection based on Barzilai-Borwein Algorithm\\nYear: 2018\\n\\nAbstract: For a massive multiple-input multiple-output (MI-MO) system, how to cope with the detection difficulties brought by increasing antennas is intractable. Linear methods such as zero-forcing (ZF) and minimum mean square error (MMSE) can achieve sub-optimal performance while suffer from high complexity because of large-scale matrix inversion. Recently, some iterative detectors such as steepest descent (SD) and conjugate gradient (CG) have been proposed to balance the complexity and performance. However, their fast convergence would not maintain when the system loading factor increases. To address the aforementioned issues, this paper 1) introduces a new iterative algorithm called Barzilai-Borwein (BB) that outperforms SD with inexpensive operations and 2) proposes its improved form entitled SDBB to accelerate the convergence even in bad conditions. Both theoretical and numerical results have demonstrated its advantages over the state-of-the-art ones. More specifically, SDBB can surpass the existing split pre-conditioned conjugate gradient (SPCG) detector by more than 2 dB at the bit error rate (BER) of 10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">3</sup>\\n when the number of users is relatively large, and reach a complexity reduction of 10%.\",\n \"Title: A Novel D-Metric for Blind Detection of Polar Codes\\nYear: 2018\\n\\nAbstract: As a known error-correcting code that has been proved to fully achieve the binary discrete memoryless channel (B-DMC) capacity, polar codes have been considered as a breakthrough in coding theory since its invention. In 2016, polar codes were selected by the 3GPP as the control channel codes for the enhance mobile broadband (eMBB) scenario. The related research of polar codes has been further pushed to the forefront of applications. In spite of the urgent practical needs, research on the algorithm design and efficient implementation of polar codes for control channels and Internet of Things (IoT) is still in infancy. This paper is to combine successful cancellation (SC) and simplified successful cancellation (SSC) decoders to propose a low-complexity algorithm that can realize blind detection of polar codes. Log-likelihood ratios (LLRs) of frozen bits are used to introduce a new metric D, which is to distinguish polar codes of different formats. The realization of blind detection of polar codes can avoid the receiver's executing complicated decoding algorithm for all polar code candidates, reducing the power, complexity, and delay.\",\n \"Title: Efficient Compressed Landweber Detector for Massive MIMO\\nYear: 2018\\n\\nAbstract: Massive multiple-input multiple-output (M-MIMO) provides better efficiency and coverage than conventional MIMO. Efficient detector, being indispensable for M-MIMO, is the focus of nowadays research. For M-MIMO, MMSE detector with exact matrix inversion works well but suffers from complexity, not to mention the performance degradation in ill-posed cases. Thus, Landweber detector (LD) and improved Landweber detector (ILD) are considered. In this paper, the compressed Landweber detector (CLD) is proposed with much lower complexity but the same performance as ILD. Numerical results show that for 128×8 MIMO with 64-QAM, CLD approximates MMSE detector with lower complexity. When BER = 10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">4</sup>\\n, the gap is only 0:24 dB with 2 iterations. When antenna configuration is 128×60, CLD can achieve 82% complexity reduction than ILD. Unified hardware architecture of ILD is proposed. Folding is considered for further reduction. With the same hardware as ILD, architecture of CLD is finally proposed.\",\n \"Title: Expectation Propagation Detection with Neumann-Series Approximation for Massive MIMO\\nYear: 2018\\n\\nAbstract: For massive multiple-input multiple-output (MIMO) systems, signal detection is always a key concern. Traditional detection methods such as minimum mean square error (MMSE) all suffer from a variety of problems in respect of complexity and performance when applied to large-scale MIMO systems. In this paper, expectation propagation (EP) algorithm is employed to guarantee high-accuracy and low-complexity of symbol detection in high-dimensional MIMO systems. Nevertheless, in the iterative updating process of EP algorithm, the inevitable matrix inversion operation is one of the key challenges to the realistic hardware implementation. Therefore, a new improved EP, which is termed as expectation propagation with Neumann-series approximation (EP-NSA), is firstly proposed to accommodate the complexity as well as the performance by executing an approximate matrix inversion with a small number of Neumann-series terms. Simulation results have shown that the proposed EP-NSA with two items achieves notable performance improvement compared to belief propagation (BP) detection when the system loading factor is relatively large. For antenna configurations with large loading factor, this approach achieves similar performance to MMSE while keeping lower computational complexity.\",\n \"Title: Arithmetic Computations Based on Chemical Reaction Networks\\nYear: 2018\\n\\nAbstract: Widely used as formalism for the analysis of chemical and biochemical systems, chemical reaction networks (CRNs) have received increasing attention as a fundamental model for molecular computation. This paper demonstrates that, with a new method, CRNs can compute most arithmetic computations (e.g., non-polynomial functions). By applying Taylor's Theorem and a finite-state machine (FSM) topology for arithmetic computations, the synthesis flow of accomplishing arithmetic computations is achieved. Since probability transmitted between designed FSMs can be naturally mapped to the concentration of molecular in solution, the whole computing process can be realized with molecular reactions instead of silicon-based hardware design. Theoretical analysis and numerical simulations have demonstrated the feasibility of the proposed approach.\",\n \"Title: LDPC Decoder Based on Markov Chain Monte Carlo Method\\nYear: 2018\\n\\nAbstract: Low-density parity check (LDPC) codes have attracted the attention of a large number of researchers with its near-Shannon performance and easy implementation features. As a data coding scheme under the 5G scenario, how to achieve efficient encoding/decoding for LDPC codes has become one of the important research topics. Under this condition, this paper 1) proposes a novel decoding algorithm for LDPC codes using the Markov Chain Monte Carlo (MCMC) method and 2) introduces two improved versions, MCMC-S and MCMC-L, which achieve better results. Simulation figures show that the improved methods outperform the traditional belief propagation (BP) decoding method in relatively short codes by more than 1 dB at the bit error rate (BER) of 10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">-3</sup>\\n. Very large scale integration (VLSI) architecture of the proposed method is also given in this paper.\",\n \"Title: A New Error Correction Scheme for Physical Unclonable Function\\nYear: 2018\\n\\nAbstract: Error correction is an indispensable component when physical unclonable functions (PUFs) are used in cryptographic applications, because environmental factors influence PUFs' performance. Nowadays, syndrome-based scheme and code-offset scheme are used in PUF error correction. In this paper, a new scheme named error correction with multiple challenge-response pairs (ECMC) is proposed to perform better than code-offset scheme under certain circumstances.\",\n \"Title: A Low-Complexity Codebook Design for Large-Scale SCMA\\nYear: 2018\\n\\nAbstract: Sparse-code multiple-access (SCMA) is an effective non-orthogonal multiple-access (NOMA) technique, which ranks one of the most promising candidates for future wireless. However, most of the existing work prefer a low-connectivity SCMA system because of the difficulties in designing proper codebook, which limits its priorities for massive connection. In this paper, we propose a systematic, low-complexity codebook design for large-scale SCMA. Stage-based generation with quadrature amplitude modulation (QAM) is adopted in the codebook design for SCMA system with arbitrary parameters, where the layer operator of each user is fixed as constellation rotation for simplification. Extension from known codebook is another proposed design manner, which allocates the known codeword repetitively based on specific allocation order. With a effectiveness metric, numerical results reveal advantages of our work. Hardware architecture of the detector is also proposed in this paper.\",\n \"Title: Adaptive Damped Jacobi Detector and Architecture for Massive MIMO Uplink\\nYear: 2018\\n\\nAbstract: For massive multiple-input multiple-output (MIMO) detection, minimum mean square error (MMSE) method can achieve close-to-optimal performance. However, its computational complexity is proportional to the third power of antenna elements due to the inevitable matrix inversion operation. Especially when the number of transmitting antennas is very large, exact MMSE detection method becomes disabled owing to the excessive complexity. In this paper, an adaptive damped Jacobi (DJ) method is proposed firstly to iteratively realize MMSE performance without the intractable matrix inversion. By automatically updating the optimal relaxation factor w with the increase of iterations, the adaptive scheme does not require careful selection of initial relaxation factor compared to the conventional fixed-w DJ method. Simulation results have shown that the proposed adaptive DJ is more applicable to the correlated MIMO channels for its great flexibility of relaxation factor ω. Additionally, the hardware architecture design is also presented in this paper.\",\n \"Title: An Adjustable Hybrid SC-BP Polar Decoder\\nYear: 2018\\n\\nAbstract: Polar codes have drawn lots of attentions for the capacity-achieving property and low encoding/decoding complexity. As two promising decoding algorithms, successive cancellation (SC) decoding shows better performance but limited by high latency. Otherwise, belief Propagation (BP) algorithm presents high throughput yet with performance degradation. In this paper, a hybrid decoding architecture combining SC and BP decoding is proposed, which could process both algorithms in unified module within one decoding step. The simulation result reflects a tradeoff between decoding latency and performance with different decomposition levels. In terms of hardware implementation, the adjustable architecture is implemented based on systolic BP decoder and look-ahead SC decoder. The hybrid decoder offers the flexibility and generality which could apply on different conditions.\",\n \"Title: Polar-coded forward error correction for MLC NAND flash memory.\\nYear: 2018\\n\\nAbstract: With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell (MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code (ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate (FER) and decoding latency. Three decoders namely binary-input, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft log-likelihood ratio (LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared with LDPC codes. The stepwise maximum mutual information (SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared with other alternatives. Hardware architectures are also given in this paper.\",\n \"Title: Optical Mobile Communications: Principles, Implementation, and Performance Analysis.\\nYear: 2019\\n\\nAbstract: Owing to the rapid growth of mobile data communication and spectrum crunch at lower radio frequency, utilizing high frequency spectrum such as millimeter wave for ultra-high data rate mobile communications becomes necessary. Yet the propagation behaviors of high frequency radio waves make mobile communications rather challenging with a lot of technical problems, such as very large propagation loss...\",\n \"Title: Low-Complexity Winograd Convolution Architecture Based on Stochastic Computing.\\nYear: 2018\\n\\nAbstract: Deep convolution neural networks (CNNs) usually require a large number of iterative convolution operations, which would consume significant amounts of hardware resources. In this paper, we propose an efficient convolution architecture based on Winograd algorithm for convolutional neural networks (CNNs), by employing stochastic computing (SC). For the first step, a fast convolution algorithm, Winograd fast convolution algorithm (WFCA), which can lower the complexity by reducing multiplications is proposed. Although stochastic computing (SC) can achieve significant reduction in hardware complexity compared with the deterministic design, its straightforward application to fast convolution is not well-suited due to the precision loss. Therefore, based on two-line SC, this paper proposes a non-scaled stochastic adder which has higher computation accuracy than the conventional stochastic adder. Numerical results have proved the advantages of the proposed design in both complexity and precision. Although preliminary, it is expected that this design can be the first step of combining neural network and stochastic computing, which are both analog, belief-based and fault-tolerant, thereby unlocking the potentiality for the widespread application of stochastic Winograd algorithm in neural network systems.\",\n \"Title: Quantum Algorithm for Spectral Regression for Regularized Subspace Learning.\\nYear: 2019\\n\\nAbstract: In this paper, we propose an efficient quantum algorithm for spectral regression which is a dimensionality reduction framework based on the regression and spectral graph analysis. The quantum algorithm involves two core subroutines: the quantum principal eigenvectors analysis and the quantum ridge regression algorithm. The quantum principal eigenvectors analysis can be performed by an efficient sparse Hamiltonian simulation. For the ridge regression, we propose a quantum algorithm that is derived from the quantum singular value decomposition method. Our quantum ridge regression algorithm is more suitable for data matrices that are non-sparse and skewed. Our analysis demonstrates that the quantum subroutines can be implemented with an approximatively polynomial speedup on a quantum computer over their classical counterparts.\",\n \"Title: Data-Rate Driven Transmission Strategy for Deep Learning Based Communication Systems.\\nYear: 2018\\n\\nAbstract: Deep learning (DL) based autoencoder is a promising architecture to implement end-to-end communication systems. In this paper, we focus on the fundamental problems of DL-based communication systems, including high rate transmission and performance analysis. To address the limited data rate issue, we first consider the error rate constraint and design a transmission algorithm to adaptively select the transmission vectors to maximize the data rate for various channel scenarios. Furthermore, a novel generalized data representation (GDR) scheme is proposed to improve the data rate of DL-based communication systems. Then, we analyze the effect of signal-to-noise ratio (SNR) and mean squared error performance of the proposed DL-based communication systems. Finally, numerical results show that the proposed adaptive transmission and GDR schemes achieve higher data rate and have lower training complexity than the conventional one-hot vector scheme. Both the new schemes and the conventional scheme have comparable block error rate (BLER) performance. According to both theoretical analysis and simulated results, it is suggested that low or wide-range training SNR is beneficial to attain good BLER performance for practical transmission with various channel scenarios.\",\n \"Title: Wide-range Dimmable Clipped Flip-OFDM For Indoor Visible Light Communications\\nYear: 2018\\n\\nAbstract: Combination of illumination and communication is a key characteristic of visible light communications. Different environments require different illumination levels. When the desired dimming level is relatively low or high, conventional optical orthogonal frequency division multiplexing (O-OFDM) will suffer severe performance deterioration due to the clipping noise. This paper proposes a novel O-OFDM scheme named clipped flip-OFDM for indoor visible light communication systems with dimming control. In the proposed clipped flip-OFDM scheme, we design a new OFDM frame structure to keep the clipped information. We can achieve different dimming levels by adjusting the values of the direct-current (DC) bias and a control factor. Furthermore, the performance of the proposed clipped flip-OFDM scheme is less affected by the dimming level. Simulation results verify that the proposed clipped flip-OFDM achieves a wide dimming range, and the achievable spectral efficiency is stable.\",\n \"Title: LOW-COMPLEXITY MESSAGE PASSING MIMO DETECTION ALGORITHM WITH DEEP NEURAL NETWORK\\nYear: 2018\\n\\nAbstract: The channel hardening-exploiting message passing detection (MPD) algorithm achieves good performance in large-scale multiple-input multiple-output (MIMO) systems. However, for not-so-large systems with larger loading factors, the MPD suffers slow convergence rate and higher complexity. In this paper, a deep neural network (DNN)-aided message passing detector, DNN-MPD, is proposed. A modified MPD algorithm is firstly presented to compensate the approximation error in MPD, aiming at accelerating the convergence and attaining better performance. The DNN-MPD is then constructed by unfolding the modified MPD, and deep learning techniques are utilized to optimize the modification factors. Numerical results are presented to demonstrate the performance of the DNN-MPD compared with the original MPD. Through one training, the DNN-MPD can be used for multiple online detections, and it reaches faster convergence rate, outperforming the original MPD in the bit error rate (BER) performance in MIMO systems with large loading factors.\",\n \"Title: An improvement for ad hoc on-demand routing protocol.\\nYear: 2003\\n\\nAbstract: The two well-known on-demand protocols for ad hoc networks - DSR and AODV show degraded performance with traffic load increase. In this paper, we propose a traffic-balanced scheme, called TB scheme, to solve this problem. The TB scheme adapts MAC layer information for routing decisions. It avoids involving heavy loaded nodes in a new route and thus balances network traffic. Simulation results show that the new scheme significantly improves DSR and AODV's performance under heavy load conditions. © 2003 IEEE.\",\n \"Title: A Large-Scale Extension of Sparse-Code Multiple-Access System.\\nYear: 2018\\n\\nAbstract: Sparse-code multiple-access (SCMA) is an effective non-orthogonal multiple-access (NOMA) technique, which ranks one of the most promising candidates for future wireless, because of its outstanding performance. However, most of the existing work prefers low-connectivity SCMA systems, which actually cannot ful fi ll their priorities for massive connection. The dif fi culties in designing suitable factor graph matrix are responsible for this situation. In this paper, we propose a design manner of factor graph matrix to realize SCMA with large-scale customers. Quasi-cyclic property with shifting is introduced in SCMA factor graph matrix, based on the rules and restrictions of SCMA design including the column weight and the overloading factor. For numerical analysis, we introduce a performance function to show the effectiveness of our proposed SCMA system, and the results reveal that our work are better than conventional ones.\",\n \"Title: Adaptive Modulation and Filter Configuration in Universal Filtered Multi-Carrier Systems.\\nYear: 2018\\n\\nAbstract: Universal filtered multi-carrier (UFMC) is a potential waveform technology, which can efficiently combat different carrier frequency offsets (CFOs) of multiple users. First, adaptive modulation and power allocation are applied for each subcarrier to meet a preset bit error rate (BER) requirement by ignoring CFOs. Then, we prove that different CFOs will cause different interference variances to adj...\",\n \"Title: Downlink Precoding with Correlation-Based User Grouping for Multiuser MISO Systems.\\nYear: 2017\\n\\nAbstract: Correlation across transmit antennas in multiple-input single-output (MISO) broadcast channel has been studied to be detrimental generally. The current downlink beamforming schemes have not considered correlation enough such that they are not suitable for the broadcast systems with high correlation among transmit antennas. We propose two novel user grouping precoders to improve the sum rate performance for the case of ill-conditioned channel and the case of small transmit antennas (i.e., the number of transmit antennas is less than that of users). The first proposed precoder partitions all the users into small groups step by step based on the condition number. Downlink beamforming is then done in a small size for the optimal channel submatrix with smaller condition number. Inter-group interference from the subsequent allocated groups is nulled out in the null spaces of the previous allocated groups. The second precoder regularizes the number of users in the first group to improve the sum rate further. Simulation results verify that our schemes outperform the current beamforming schemes for the case of high transmit correlation. Moreover, the proposed precoders allow to be applied for the case of small antennas.\",\n \"Title: Polar-Coded Forward Error Correction for MLC NAND Flash Memory Polar FEC for NAND Flash Memory.\\nYear: 2018\\n\\nAbstract: With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell (MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code (ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate (FER) and decoding latency. Three decoders namely binary-input, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft log-likelihood ratio (LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared to LDPC codes. The stepwise maximum mutual information (SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared to other alternatives. Hardware architectures are also given in this paper.\",\n \"Title: A Novel Estimated Wideband Geometry-Based Vehicle-to-Vehicle Channel Model Using an AoD and AoA Estimation Algorithm.\\nYear: 2019\\n\\nAbstract: In this paper, we propose an estimated wideband geometry-based channel model for vehicleto-vehicle (V2V) communication environments, which is based on an angle of departure (AoD) and angle of arrival (AoA) estimation algorithm, to determine the ellipse scattering region and to efficiently study the V2V channel characteristics for different propagation delays, i.e., per-tap channel statistics. In the first stage, we estimate the AoD and AoA for the first tap. In this case, the ellipse-scattering region for the first tap can be determined. Then, we estimate the ellipse channel models for other taps based on the estimated model parameters for the first tap. Furthermore, the spatial cross-correlation functions (CCFs) are derived and thoroughly investigated for different propagation delays. The excellent agreement is achieved between the proposed channel statistics and prior results and measurements.\",\n \"Title: Novel Channel Quality Indicator Prediction Scheme for Adaptive Modulation and Coding in High Mobility Environments.\\nYear: 2019\\n\\nAbstract: In this paper, a novel channel quality indicator (CQI) prediction scheme for adaptive modulation and coding in high-speed mobility environments is proposed, where the wavenumber spectrum segmentation filters' bank is utilized to improve the estimation accuracy of channel prediction algorithm by enhancing the correlation of wireless channels in each orthogonal subspace. In the proposed method, the channel estimation, channel prediction, and signal-to-noise-rate (SNR) prediction are processed on the orthogonal subspace level, which can significantly decrease the mismatch level of the feedback CQI under the fast time-varying channels. Based on the predicted SNR after subspace signal combination, the effective SNR is obtained and is utilized to calculate the feedback CQI parameter. The autocorrelation function and spatial fading rate are analyzed with different feedback delays, which show that our proposed scheme provides stronger correlation of channels with the order of wavenumber spectrum segmentation filters' bank increasing. The simulation results show that the proposed scheme can achieve better throughput performance even with larger feedback delay in high-speed mobility environments.\",\n \"Title: Three-Dimensional Non-Stationary Wideband Geometry-Based UAV Channel Model for A2G Communication Environments.\\nYear: 2019\\n\\nAbstract: In this paper, we propose a novel three-dimensional multiple-input multiple-output channel model to describe the air-to-ground (A2G) communication environments. The model introduces the unmanned aerial vehicle (UAV) transmitter and ground mobile receiver (MR) located at the foci points of the boundary ellipsoid, while different ellipsoids represent the propagation properties for different time delays. In light of this, we are able to investigate the propagation properties of the A2G channel model for different time delays. Furthermore, the time-varying parameters of the azimuth angle of departure, the elevation angle of departure, the azimuth angle of arrival, and elevation angle of arrival are derived to properly describe the channel non-stationarity, which is caused by the motion of the UAV transmitter, cluster, and MR. The impacts of the movement properties of the cluster in both the azimuth and elevation planes are investigated on the channel characteristics, i.e., spatial cross-correlation functions, temporal autocorrelation functions, Doppler power spectrum density, and power delay profiles.\",\n \"Title: Molecular Polar Belief Propagation Decoder and Successive Cancellation Decoder\\nYear: 2019\\n\\nAbstract: Polar codes have been adopted for the enhanced mobile broadband control channels for the 5th communication system. By constructing chemical reaction networks (CRNs), this paper proposes a method of synthesizing polar belief propagation (BP) decoder and successive cancellation (SC) decoder. The proposed method is suitable for polar codes with arbitrary code length and code rate. Reactions in the proposed design could be experimentally implemented with deoxyribonucleic acid (DNA) strand displacement reactions, making the proposed polar decoders promising for wide application in nanoscale devices. Theoretical analysis and simulation results have validated the feasibility of this method.\",\n \"Title: Sure-Tista: A Signal Recovery Network For Compressed Sensing\\nYear: 2019\\n\\nAbstract: Deep neural network (DNN) has a wide range of applications in various fields, including solving sparse inverse problems. In this paper, we propose a novel network called the Stein's unbiased risk estimate based-trainable iterative thresholding algorithm (SURE-TISTA) for sparse signal recovery problems. Without prior information, SURE-TISTA outperforms TISTA, an algorithm based on the minimum mean squared error (MMSE) estimator. SURE-TISTA also shows a great robustness in many cases including large-scale and large-variance problems. Meanwhile, SURE-TISTA uses fewer learnable variables to achieve similar performance as learned approximate message passing (LAMP), which has more learnable parameters. Without any error measure estimator, SURE-TISTA achieves a near MMSE-based performance. Our numerical results indicate that SURE-TISTA is superior to TISTA and other traditional algorithms in many aspects, which can be promising in image denoising.\",\n \"Title: Efficient Belief Propagation Detection Based On Channel Hardening For Massive Mimo\\nYear: 2019\\n\\nAbstract: For massive multiple-input multiple-output (MIMO) detection, belief propagation (BP) based on graphical models has become a popular detection algorithm since it provides a good tradeoff between performance and complexity. To further lower the complexity of BP detection, an efficient BP detection based on channel hardening (BP-CH) is proposed. In this paper, the comparison in terms of both performance and complexity between proposed BP-CH and general BP is firstly investigated exhaustively. Simulation results have shown that the proposed BP-CH achieves similar performance behavior as general BP while keeping lower computational complexity. Additionally, an folded hardware architecture for proposed BP-CH detector is designed to improve the implementation efficiency. Meanwhile, VLSI implementation results have verified the great advantage of BP-CH regarding hardware overhead, especially for scenarios with large system loading factor.\",\n \"Title: An Improved Software List Sphere Polar Decoder with Synchronous Determination\\nYear: 2019\\n\\nAbstract: Being the first codes achieving the capacity of symmetric binary-input discrete memoryless channels, polar codes have been favorable and standardized for enhanced mobile broadband (eMBB) control channels. In future mobile communications, the entire system is required to be flexible and adaptive to varying scenarios. Therefore, efficient software implementation of polar decoder is expected. Existin...\",\n \"Title: A Multicast Scheme Based on Fidelity Metrics in Quantum Networks.\\nYear: 2019\\n\\nAbstract: A multicast scheme based on fidelity metrics in quantum networks is proposed in this paper. First of all, according to the fidelity of copies in an asymmetric mechanism of 1 -> 1 + 1 + 1 + 1 which is derived, the way of information transmission in the quantum networks is defined: one is one-to-one transmission based on the teleportation and the other is one-to-many lossy transmission based on quantum cloning mechanism. Second, in a specified quantum network which is a connected graph, a source node can randomly assign multicast group members. Then, with constraints of the number of replicas and the maximum number of hops of the shortest path, an optimal multicast tree is constructed to obtain maximum fidelity. Finally, the simulation results show that the proposed scheme can select the optimal path from the source node to the multicast members for the specified quantum network. With the increase of multicast group members, the average value of information fidelity obtained by all members decreases. Compared with the multicast tree constructed by the KMB algorithm, which is used to construct the Steiner tree in classical communication, the proposed schemes make the information fidelity obtained by multicast group members improve significantly.\",\n \"Title: Optical Adaptive Antenna Array For Multiuser Mobile Optical Communication\\nYear: 2019\\n\\nAbstract: In this paper, an optical adaptive antenna array system for multi-user optical mobile communication is studied. A coherent signal source is embedded in a spherical optical phased cell array with an external spherical lens system. The system can predict the signal power of the receiving end according to the channel transfer matrix and perform power compensation when transmitting the signal. Correspondingly, a pure phase lossless desired light field recovery algorithm is proposed and used for space division multiple access and free power allocation of antenna array systems. A small-scale optical adaptive antenna array experimental system is built and tested with good performance and consistent with the expected results.\",\n \"Title: Joint spatial modulation and beamforming based on statistical channel state information for hybrid massive MIMO communication systems\\nYear: 2019\\n\\nAbstract: Spatial modulation is a promising transmission scheme for massive multiple-input multiple-output (MIMO) systems to improve energy efficiency. In this study, considering the low-complexity hybrid structure, the authors propose a joint spatial modulation and beamforming scheme for a hybrid massive MIMO system in both single user and multi-user scenarios. Specifically, a design criterion of the channel control parameter is provided to reduce the high correlation among different channel coefficients in the hybrid massive MIMO system. In addition, with the statistical channel state information acquired at the base station, the optimum analogue beamforming vectors are designed with the goal of maximising the signal to leakage and noise ratio in the multi-user scenario. Furthermore, the upper bound, the lower bound as well as the closed form approximation of achievable spectral efficiency of the proposed scheme are derived for both single user and multi-user scenarios. Numerical simulation results demonstrate that the proposed scheme outperforms the conventional MIMO scheme.\",\n \"Title: A 3-D Non-Stationary Wideband Geometry-Based Channel Model for MIMO Vehicle-to-Vehicle Communications in Tunnel Environments\\nYear: 2019\\n\\nAbstract: In this paper, we present a three-dimensional (3-D) wideband geometry-based channel model for multiple-input and multiple-output vehicle-to-vehicle (V2V) communication in tunnel environments. We introduce a two-cylinder model to describe moving vehicles, as well as multiple confocal semi-ellipsoid models to depict internal surfaces of tunnel walls. The received signal is constructed as a sum of direct line-of-sight propagations, rays with single and double interactions. The movement between the mobile transmitter and mobile receiver results in time-varying geometric statistics that make our channel model non-stationary. Using this channel model, the proposed channel characteristics are studied for different V2V scenarios. The numerical results demonstrate that the proposed 3-D non-wide-sense stationary (WSS) wideband channel model is practical for characterizing real V2V channels.\",\n \"Title: Outage Analysis and Beamwidth Optimization for Positioning-Assisted Beamforming\\nYear: 2022\\n\\nAbstract: Beamforming based on channel estimation can be computationally intensive and inaccurate when the antenna array is large, while positioning information can reduce the complexity. In this work, we study the outage probability of positioning-assisted beamforming systems. Closed-form outage probability bounds are derived by considering positioning error, link distance and beamwidth. Based on the analytical result, we show that the beamwidth should be optimized with respect to the link distance and the transmit power, and such optimization significantly suppresses the outage probability.\",\n \"Title: A Novel Method to Estimate the Coordinates of LEDs in Wireless Optical Positioning Systems\\nYear: 2021\\n\\nAbstract: Traditional visible light positioning (VLP) systems estimate receivers' coordinates based on the known light-emitting diode (LED) coordinates. However, the LED coordinates are not always known accurately. Because of the structural changes of the buildings due to temperature, humidity or material aging, even measured by highly accurate laser range finders, the LED coordinates may change unpredictab...\",\n \"Title: Improving Approximate Expectation Propagation Massive MIMO Detector With Deep Learning\\nYear: 2021\\n\\nAbstract: In this letter, an efficient model-driven deep learning (DL) based massive multiple-input multiple-output (MIMO) detector is proposed by improving the approximate expectation propagation (EPA) algorithm, named EPANet. Specifically, EPANet is constructed by unfolding the iterative EPA detector and adding learnable parameters to enhance the performance and convergence robustness through the DL appro...\",\n \"Title: Low-Complexity Construction of Polar Codes Based on Genetic Algorithm\\nYear: 2021\\n\\nAbstract: How to efficiently rank the reliability order of the channels is critical for polar code construction. A new polar code construction framework tailored to a given decoding algorithm based on the genetic algorithm has been proposed to achieve an error correction performance gain. However, the time complexity of this scheme is extremely high. In this letter, a scheme based on a hash table is propose...\",\n \"Title: Successive-Coded Spatial Shift Keying Modulation for MIMO Wireless Communications\\nYear: 2021\\n\\nAbstract: Spatial domain modulation employs spatial degree of freedom to convey information bits. Traditional spatial domain modulation schemes include spatial modulation, spatial shift keying (SSK), and variations of these two schemes. To fully make use of the spatial degree of freedom and improve the achievable data rate of traditional spatial domain modulation schemes, we propose a successive-coded SSK (...\",\n \"Title: Performance Analysis of Multi-Branch Reconfigurable Intelligent Surfaces-Assisted Optical Wireless Communication System in Environment With Obstacles\\nYear: 2021\\n\\nAbstract: Since optical links are easily blocked by obstacles in the environment, they have been considered difficult to directly perform wireless communications. However, reconfigurable intelligent surfaces (RISs), as a new type of digital coding meta-materials, can significantly improve the coverage of optical communication by establishing new links. We propose a controllable multi-branch wireless optical...\",\n \"Title: Hardware Implementation For Bipartite Belief Propagation Polar Decoding With Bit Flipping\\nYear: 2021\\n\\nAbstract: For the scenarios with high throughput requirements, the belief propagation (BP) decoding is one of the most promising decoding strategies for polar codes. By pruning the redundant variable nodes (VNs) and check nodes (CNs) in the original factor graph, the graph is condensed to a sparse bipartite graph that is similar to the graph for low-density parity-check (LDPC) codes. In this paper, we introduce the bit flipping scheme into the LDPC-like BP (L-BP) decoding and propose two methods to identify the error-prone VNs. By additional decoding attempts, the L-BP flip (L-BPF) decoding improves the error-correction performance with a similar average complexity for high E-b/N-0 values. The simulation results show that the L-BPF decoding achieves 0.25 dB gain compared with the L-BP decoding. Finally, a parallel decoder with the proposed L-BPF algorithm for an (256,128) polar code is implemented using 65nm CMOS technology, and it delivers a throughput of 1877.3 Mbps.\",\n \"Title: A Geometry-Based Stochastic Channel Model And Its Application For Intelligent Reflecting Surface Assisted Wireless Communication\\nYear: 2021\\n\\nAbstract: Intelligent reflecting surface (IRS) is a new concept originating from metamaterials, which can achieve beamforming through controllable passive reflecting. This device makes it possible to engineer the wireless communication environment, and has drawn increasing attention. However, the associated channel models in current literature are mainly borrowed from conventional wireless channel models directly, omitting the unique features of IRS. In this paper, a geometry-based stochastic channel model for IRS-assisted wireless communication system is employed. The model has certain accuracy and low computational complexity. In particular, it captures the correlations of subchannels associated with different IRS elements, which is typically not considered in current works. Based on this channel model and the derived channel spatial correlation functions (CFs), an iterative reflection coefficients configuration method is proposed exploiting statistical channel state information to maximise the ergodic channel capacity. The impacts of the IRS spatial positions as well as the number of the IRS elements on the ergodic channel capacity is investigated through simulations. It is found that to obtain a larger ergodic channel capacity, the IRS should be placed in the vicinity of either the transmitter side or the receiver side, which is a useful guideline for practical deployment.\",\n \"Title: Orbital Angular Momentum Multiplexing Communication System Over Atmospheric Turbulence With K-Best Detection\\nYear: 2021\\n\\nAbstract: As the optical communication technology advances, vortex beam with orbital angular momentum (OAM) has gained wide attention due to its potential to significantly increase the channel capacity. Under the influence of atmospheric turbulence, there are still challenging problems in the OAM multiplexing system. To the best of our knowledge, in this paper one multiple-input-multiple-output (MIMO) detection technology named K-best detection, is first applied to the OAM multiplexing system. Numerical simulation results indicate the proposed solution enhances the performance of the optical communication system compared with data-aided least mean square (DA-LMS) and minimum mean squared error (MMSE) detection. Furthermore, with MMSE sorted QR decomposition (MMSE-SQRD) preprocessing, the performance of K-best detection can be further improved. When C, about 4.4 dB signal-to-noise ratio (SNR) gain can be obtained by preprocessing at k = 2 while the complexity is not significantly increased. Computational complexity is also analyzed in this paper, results show that K-best detection with winner path extension (WPE) algorithm can achieve 43% system complexity reduction, achieving a compromise between performance and complexity in K-best detection.\",\n \"Title: Efficient Soft-Output Gauss–Seidel Data Detector for Massive MIMO Systems\\nYear: 2021\\n\\nAbstract: For massive multiple-input multiple-output (MIMO) systems, linear minimum mean-square error (MMSE) detection has been shown to achieve near-optimal performance but suffers from excessively high complexity due to the large-scale matrix inversion. Being matrix inversion free, detection algorithms based on the Gauss–Seidel (GS) method have been proved more efficient ...\",\n \"Title: Design of a Broadband Microwave Sampler Based on Step Recovery Diode\\nYear: 2021\\n\\nAbstract: A new type of broadband microwave sampler is designed in this paper. It can work in 20–50 GHz. The circuit of microwave sampler has the following three parts, including the balun, pulse generator circuit and sampling diode circuit. In the pulse generator circuit, we only use the step recovery diode (SRD) to generate very narrow sampling pulse. Compared with the short circuit microstrip line pulse ...\",\n \"Title: A 3D Stochastic Channel Model for 6G Wireless Double-IRS Cooperatively Assisted MIMO Communications\\nYear: 2021\\n\\nAbstract: In this paper, we propose a three-dimensional (3D) stochastic channel model for double intelligent reflecting surface (IRS) cooperatively assisted multiple-input multiple-output (MI-MO) communications, where two distributed IRSs are respectively deployed near a mobile transmitter (MT) and a mobile receiver (MR). The double-IRS is distributed on the surface of buildings to assist the transmitter to...\",\n \"Title: Location Aware Multi-cell MIMO Communications Assisted by Optical Positioning\\nYear: 2021\\n\\nAbstract: This paper proposes a high-energy-efficiency location aware multi-cell multiple input multiple output (MIMO) communication system assisted by optical positioning. The location information acquisition method in the optical positioning subsystem has been designed, which can perform real-time angle of arrival and distance estimation for users and other scatterers and identify the users through the fe...\",\n \"Title: Quantum algorithm for Laplacian eigenmap via Rayleigh quotient iteration\\nYear: 2022\\n\\nAbstract: Laplacian eigenmap (LE) is a geometrically motivated algorithm for dimensionality reduction. However, as the data dimensionality increasing, it is intractable for classical computers to solve the generalized eigen-problem which is a crucial subroutine of the LE. In this work, we propose a quantum algorithm for Laplacian eigenmap (QLE). Compared with classical LE, our QLE can provide an exponential speedup in eigenmapping step over classical counterparts under some mild condition. In our scheme, we first present a quantum subroutine for adjacency graph construction based on the controlled SWAP test and maximum searching algorithm. Second, a variational quantum generalized eigensolver (VQGE) is proposed to solve the generalized eigen-problem Ax=lambda Bx. The proposed VQGE avoids the determination of the partial derivatives of the Rayleigh quotient and the difficulty of selecting hyperparameter. Finally, as a proof-of-principle, we conduct a numerical simulation to solve the variational quantum Laplacian eigenmap of randomly generated data points.\",\n \"Title: Asymptotic Analysis of Diversity Receptions Over Correlated Lognormal-Rician Fading Channels\\nYear: 2021\\n\\nAbstract: Lognormal-Kit:km random variables (RV) can model large-scale and small-scale fading, line-of-sight and non-line-of-sight channels in wireless communications. However, the versatile stochastic tool is mathematically intractable for correlated cases. In this work, we derive closed-form expressions for the outage probabilities of diversity receptions over dual-branch lognormal-Rician fading channels with arbitrary correlation at high signal-to-noise ratio (SNR). The analytical results show that the lognormal RV and the Rician RV, respectively, contribute an exponential factor and a fractional factor to the outage probability expressions. Some important insights are revealed based on the elegant expressions. For example, negative correlation between the lognormal RVs can suppress the outage probability, and the phase of the complex correlation coefficient between the accompanying Gaussian RVs in the Rician channels can significantly influence the performance.\",\n \"Title: A Statistical MIMO Channel Model for Reconfigurable Intelligent Surface Assisted Wireless Communications\\nYear: 2022\\n\\nAbstract: Reconfigurable intelligent surface (RIS) consisting of a large number of programmable near-passive units has been a hot topic in wireless communications due to its capability in providing smart radio environments to enhance the communication performance. However, the existing research are mainly based on simplistic channel models, which will, in principle, lead to inaccurate analysis of the system...\",\n \"Title: Capacity Results for Range-Limited SISO and MISO Dimmable VLC Channels\\nYear: 2022\\n\\nAbstract: This paper investigates the capacity results of dimmable visible light communications (VLCs) channel under practical range-limited constraints. Upper and lower bounds for both single-input single-output (SISO) and multiple-input single-output (MISO) scenarios which are valid in all signal-to-noise (SNR) region are derived. We reveal that the SISO capacity is a symmetrical function of the dimming t...\",\n \"Title: Fast Iterative Soft-Output List Decoding of Polar Codes\\nYear: 2022\\n\\nAbstract: Iterative detection and decoding (IDD) enjoys a higher capacity than separate detection and decoding (SDD). However, IDD requires both the detector and the decoder to support soft input and soft output. Considering the standard channel codes in 5G communication systems, the preferred decoder for polar codes, the successive cancellation list (SCL) decoder, outputs only hard decisions on the side of codeword. Yet, current soft-output polar decoders, such as belief propagation (BP) and soft cancellation (SCAN), are much inferior to the SCL decoders in terms of error correction performance. To this end, we propose a soft-output list (SOL) decoder in this paper, which considers both hypotheses of 0 and 1 for unreliable bits and keeps the \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">a-priori</i>\\n likelihoods for reliable bits, so that it can provide soft output and satisfactory error-rate performance at the same time. Exploiting the property of special nodes, the resulting FastSOL decoder can directly return soft messages from these nodes, thus speeding up the decoding. The error-rate performance of the FastSOL decoder enhances as the number of iterations increases in the non-IDD setup. The proposed FastSOL decoder can also be applied in the IDD system. Concatenated with a maximum \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">a-posteriori</i>\\n detector in ten IDD loops, our decoder with a list size of eight exhibits over 1 dB gain compared to using the SCAN decoder for polar codes with length 256 and half rate, which also outperforms the state-of-the-art soft list decoder by 0.12 dB in the same settings with a higher computational complexity, but comparable decoding latency.\",\n \"Title: An Efficient Stochastic Convolution Architecture Based on Fast FIR Algorithm\\nYear: 2022\\n\\nAbstract: By utilizing stochastic computing (SC), the hardware consumption of convolutional neural networks (CNNs) can be decreased significantly. However, long stream length is required to produce acceptable results, which leads to extended computation time. As a result, the inherent random fluctuation error and long latency of processing random bitstreams have made previous SC-CNN implementations ineffici...\",\n \"Title: Efficient MMSE-PIC Detection for Polar-Coded System Using Tree-Structured Gray Codes\\nYear: 2022\\n\\nAbstract: This letter proposes an iterative multiple-input multiple-output (MIMO) receiver for polar-coded system using minimum mean-square error parallel interference cancellation (MMSE-PIC) algorithm. And we propose a new kind of tree-structured Gray codes to reduce the computational complexity of MMSE-PIC without performance degradation. Simulation results indicate that, for a 64 \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\times $ </tex-math></inline-formula>\\n 4 MIMO system, the iterative detection and decoding (IDD) scheme with different decoding algorithms outperforms the separate detection and decoding (SDD) scheme 0.35 ~ 0.58 dB at the frame error rate (FER) of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$10^{-3}$ </tex-math></inline-formula>\\n when the number of iterations is four.\",\n \"Title: Wireless Optical Positioning With Multiple Photodiodes and LED Clusters\\nYear: 2022\\n\\nAbstract: Visible light positioning (VLP) systems provide higher accuracy and lower costs compared to their radio-frequency counterparts. Angle-of-arrival (AOA) based VLP systems are stable and accurate. However, existing AOA VLP systems with a photodiodes (PD) array usually require an unrotated receiver, densely placed LEDs, or auxiliary devices such as accelerometers and gyroscopes. In this paper, we develop an approach to exploit LED clusters and a PD array to locate the receiver. The new approach increases the angle-difference-of-arrival (ADOA) positioning accuracy and circumvents the rotation estimation in AOA positioning. More importantly, the method only requires the solution of linear equation sets, which is computationally efficient. Simulations show that the proposed positioning method can achieve an average mean error below 0.1 m within a 3 m × 3 m area.\",\n \"Title: A 3D Non-Stationary MIMO Channel Model for Reconfigurable Intelligent Surface Auxiliary UAV-to-Ground mmWave Communications\\nYear: 2022\\n\\nAbstract: Unmanned aerial vehicle (UAV) communications exploiting millimeter wave (mmWave) can satisfy the increasing data rate demands for future wireless networks owing to the line-of-sight (LoS) dominated transmission and flexibility. In reality, the LoS link can be easily and severely blocked due to poor propagation environments such as tall buildings or trees. To this end, we introduce a reconfigurable intelligent surface (RIS), which passively reflects signals with programmable reflection coefficients, between the transceivers to enhance the communication quality. Specifically, in this paper we generalize a three-dimensional (3D) non-stationary wideband end-to-end channel model for RIS auxiliary UAV-to-ground mmWave multiple-input multiple-output (MIMO) communication systems. By modeling the RIS as a virtual cluster, we study the \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">power delivering capability</i>\\n of RIS as well as the \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">fading characteristic</i>\\n of the proposed channel model. Important channel statistical properties are derived and thoroughly investigated, and the impact of RIS reflection phase configurations on these statistical properties is studied, which provides guidelines for the practical system design. The agreement between theoretical and simulated as well as measurement results validate the effectiveness of the proposed channel model.\",\n \"Title: Approximate Message Passing for Channel Estimation in Reconfigurable Intelligent Surface Aided MIMO Multiuser Systems\\nYear: 2022\\n\\nAbstract: Channel estimation is one of the main challenges for implementing reconfigurable intelligent surface (RIS)-aided communication system with a large number of antennas at the base station (BS) because RIS is equipped with many passive reflective elements without active transmitting/receiving and signal processing abilities. In this paper, we focus on the channel estimation in a general RIS-aided multi-user mmWave communication system. Specifically, a novel two-phase channel estimation scheme consisting of on-line and off-line phases is proposed to estimate the BS-RIS channel, RIS-user channel, and BS-user channel, respectively. Inspired by the characteristics of few scatterers in mmWave communication systems, the antenna domain channels are converted into the virtual angular domain channels by using the discrete Fourier transform (DFT) matrix. Thus, the estimation problem can be formulated as a compressed sensing (CS) problem, and solved by using efficient vector approximate message passing (VAMP) algorithm with expectation-maximization (EM) to learn unknown parameters and obtain the estimates simultaneously. Simulation results show that, the above algorithm with two choices of prior distributions in the proposed mmWave RIS-aided multi-user system has fast convergence speed and desirable estimation performance.\",\n \"Title: Multi-User Successive-Coded Spatial Modulation Scheme Based on Beamforming\\nYear: 2022\\n\\nAbstract: By combining an existing successive-coded spatial shift keying (SC-SSK) modulation scheme with a modulation scheme that uses the traditional constellation, we propose a new successive coded spatial modulation (SC-SM) scheme. This scheme uses spatial domain and constellation domain to jointly transmit information bits, which increases the achievable rate of the system. In order to extend the SC-SM scheme to multi-user scenario, a multi-user SC-SM (MU-SC-SM) scheme based on beamforming is proposed. The proposed MU-SC-SM scheme not only eliminates the inter-user interference (IUI) and enhances the received signal-to-noise ratio (SNR) of the served user, but also resolves the conflict between beamforming and spatial modulation. The achievable rate, the bit-error-rate (BER) performance and computational complexity of the proposed MU-SC-SM scheme are analyzed in detail. The impacts of the imperfect channel state information on the BER performance are also analyzed. Simulations are carried out to verify that the proposed MU-SC-SM scheme is superior to existing multi-user spatial modulation schemes in BER performance.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":118,"string":"118"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":77,"string":"77"}}},{"rowIdx":78,"cells":{"question_id":{"kind":"string","value":"Noel E O Connor"},"question":{"kind":"string","value":"Generate an abstract for the title \"K-Space Interactive Search\" using the following items: K-Space, Interactive Search system, Content-based video retrieval, VideOlympics, User interface."},"answer":{"kind":"string","value":"In this paper we will present the K-Space1 Interactive Search system for content-based video information retrieval to be demonstrated in the VideOlympics. This system is an extension of the system we developed as part of our participation in TRECVID 2007 [1]. In TRECVID 2007 we created two interfaces, known as the 'Shot' based and 'Broadcast' based interfaces. Our VideOlympics submission takes these two interfaces and the lessons learned from our user experiments, to create a single user interface which attempts to leverage the best aspects of both."},"correct_answer":{"kind":"string","value":"In this paper we will present the K-Space1 Interactive Search system for content-based video information retrieval to be demonstrated in the VideOlympics. This system is an extension of the system we developed as part of our participation in TRECVID 2007 [1]. In TRECVID 2007 we created two interfaces, known as the 'Shot' based and 'Broadcast' based interfaces. Our VideOlympics submission takes these two interfaces and the lessons learned from our user experiments, to create a single user interface which attempts to leverage the best aspects of both."},"documents":{"kind":"list like","value":["Title: A Low-Cost Head and Eye Tracking System for Realistic Eye Movements in Virtual Avatars\nYear: 2014\n\nAbstract: A virtual avatar or autonomous agent is a digital representation of a human being that can be controlled by either a human or an artificially intelligent computer system. Increasingly avatars are becoming realistic virtual human characters that exhibit human behavioral traits, body language and eye and head movements. As the interpretation of eye and head movements represents an important part of nonverbal human communication it is extremely important to accurately reproduce these movements in virtual avatars to avoid falling into the well-known \\\"uncanny valley\\\". In this paper we present a cheap hybrid real-time head and eye tracking system based on existing open source software and commonly available hardware. Our evaluation indicates that the system of head and eye tracking is stable and accurate and can allow a human user to robustly puppet a virtual avatar, potentially allowing us to train an A.I. system to learn realistic human head and eye movements.","Title: Inexpensive fusion methods for enhancing feature detection\nYear: 2007\n\nAbstract: Recent successful approaches to high-level feature detection in image and video data have treated the problem as a pattern classification task. These typically leverage the techniques learned from statistical machine learning, coupled with ensemble architectures that create multiple feature detection models. Once created, co-occurrence between learned features can be captured to further boost performance. At multiple stages throughout these frameworks, various pieces of evidence can be fused together in order to boost performance. These approaches whilst very successful are computationally expensive, and depending on the task, require the use of significant computational resources. In this paper we propose two fusion methods that aim to combine the output of an initial basic statistical machine learning approach with a lower-quality information source, in order to gain diversity in the classified results whilst requiring only modest computing resources. Our approaches, validated experimentally on TRECVid data, are designed to be complementary to existing frameworks and can be regarded as possible replacements for the more computationally expensive combination strategies used elsewhere.","Title: Automated annotation of landmark images using community contributed datasets and web resources\nYear: 2010\n\nAbstract: A novel solution to the challenge of automatic image annotation is described. Given an image with GPS data of its location of capture, our system returns a semantically-rich annotation comprising tags which both identify the landmark in the image, and provide an interesting fact about it, e.g. \"A view of the Eiffel Tower, which was built in 1889 for an international exhibition in Paris\". This exploits visual and textual web mining in combination with content-based image analysis and natural language processing. In the first stage, an input image is matched to a set of community contributed images (with keyword tags) on the basis of its GPS information and image classification techniques. The depicted landmark is inferred from the keyword tags for the matched set. The system then takes advantage of the information written about landmarks available on the web at large to extract a fact about the landmark in the image. We report component evaluation results from an implementation of our solution on a mobile device. Image localisation and matching offers 93.6% classification accuracy; the selection of appropriate tags for use in annotation performs well (F1M of 0.59), and it subsequently automatically identifies a correct toponym for use in captioning and fact extraction in 69.0% of the tested cases; finally the fact extraction returns an interesting caption in 78% of cases.","Title: Dual-sensor fusion for indoor user localisation\nYear: 2011\n\nAbstract: In this paper we address the automatic identification of indoor locations using a combination of WLAN and image sensing. Our motivation is the increasing prevalence of wearable cameras, some of which can also capture WLAN data. We propose to use image-based and WLAN-based localization individually and then fuse the results to obtain better performance overall. We demonstrate the effectiveness of our fusion algorithm for localisation to within a 8.9m2 room on very challenging data both for WLAN and image-based algorithms. We envisage the potential usefulness of our approach in a range of ambient assisted living applications.","Title: Multimodal Identification of Journeys\nYear: 2010\n\nAbstract: Due to the ubiquity of localisation technology, users now have the ability to keep a record of their own location, as a kind of ‘location diary’. Such a large collection of data can become unmanageable without some way to structure that data to make it useful and searchable. We address this problem of structuring location data by proposing a framework for classifying the data into often-traversed routes. In this work, commonly traversed routes are identified with clusters based on sensed data. Our framework does not rely on any one source of location information, but can fuse data from multimodal localisation sources. We demonstrate the effectiveness of our algorithm by examining the combination of GPS, wireless signal strength readings and image-matching on very challenging data in a variety of environmental conditions. By fusing these three modalities we obtained better performance than any individual or combination of two modalities. As it can be orientated towards the needs and capabilities of the user based on context, this method becomes useful for some ambient assisted living applications.","Title: Exploiting contextual data for event retrieval in surveillance video\nYear: 2009\n\nAbstract: Contextual information is vital for the robust extraction of semantic information in automated surveillance systems. We have developed a scene independent framework for the detection of events in which we provide 2D and 3D contextual data for the scene under surveillance via a novel fast and convenient interface tool. In addition, the proposed framework illustrates the use of integral images, not only for detection, as with the classic Viola-Jones object detector, but also for efficient tracking. Finally, we provide a quantitative assessment of the performance of the proposed system in a number of physical locations via groundtruthed datasets.","Title: Passively recognising human activities through lifelogging\nYear: 2011\n\nAbstract: Lifelogging is the process of automatically recording aspects of one's life in digital form. This includes visual lifelogging using wearable cameras such as the SenseCam and in recent years many interesting applications for this have emerged and are being actively researched. One of the most interesting of these, and possibly the most far-reaching, is using visual lifelogs as a memory prosthesis but there are also applications in job-specific activity recording, general lifestyle analysis and market analysis. In this work we describe a technique which allowed us to develop automatic classifiers for visual lifelogs to infer different lifestyle traits or characteristics. Their accuracy was validated on a set of 95k manually annotated images and through one-on-one interviews with those who gathered the images. These automatic classifiers were then applied to a collection of over 3million lifelog images collected by 33 individuals sporadically over a period of 3.5years. From this collection we present a number of anecdotal observations to demonstrate the future potential of lifelogging to capture human behaviour. These anecdotes include: the eating habits of office workers; to the amount of time researchers spend outdoors through the year; to the observation that retired people in our study appear to spend quite a bit of time indoors eating with friends. We believe this work demonstrates the potential of lifelogging techniques to assist behavioural scientists in future.","Title: Automatic Summarization of Rushes Video Using Bipartite Graphs\nYear: 2010\n\nAbstract: In this paper we present a new approach for automatic summarization of rushes video. Our approach is composed of three main steps. First, based on a temporal segmentation, we filter sub-shots with low information content not likely to be useful in a summary. Second, a method using maximal matching in a bipartite graph is adapted to measure similarity between the remaining shots and to minimize inter-shot redundancy by removing repetitive retake shots common in rushes content. Finally, the presence of faces and the motion intensity are characterised in each sub-shot. A measure of how representative the sub-shot is in the context of the overall video is then proposed. Video summaries composed of keyframe slideshows are then generated. In order to evaluate the effectiveness of this approach we re-run the evaluation carried out by the TREC, using the same dataset and evaluation metrics used in the TRECVID video summarization task in 2007 but with our own assessors. Results show that our approach leads to a significant improvement in terms of the fraction of the TRECVID summary ground truth included and is competitive with other approaches in TRECVID 2007.","Title: Enhancing the Functionality of Interactive TV with Content-Based Multimedia Analysis\nYear: 2009\n\nAbstract: In this paper we describe how content-based analysis techniques can be used to provide much greater functionality to the users of an interactive TV (iTV) device. We describe several content-based multimedia analysis techniques and how some of these can be exploited in the iTV domain, resulting in the provision of a set of powerful functions for iTV users. To validate our ideas, we introduce an iTV application we developed which incorporates some of these techniques into a simple set of user features, in order to demonstrate the usefulness of content-based techniques for iTV. The contribution of this paper is not to provide an in-depth discussion on each of the individual content-based techniques, but rather to show how many of these powerful technologies can be incorporated into an interactive TV system.","Title: Integrating multiple sensor modalities for environmental monitoring of marine locations\nYear: 2008\n\nAbstract: In this paper we present preliminary work on integrating visual sensing with the more traditional sensing modalities for marine locations. We have deployed visual sensing at one of the Smart Coast WSN sites in Ireland and have built a software platform for gathering and synchronizing all sensed data. We describe how the analysis of a range of different sensor modalities can reinforce readings from a given noisy, unreliable sensor.","Title: Object-Based access to TV rushes video\nYear: 2006\n\nAbstract: Recent years have seen the development of different modalities for video retrieval. The most common of these are (1) to use text from speech recognition or closed captions, (2) to match keyframes using image retrieval techniques like colour and texture [6] and (3) to use semantic features like “indoor”, “outdoor” or “persons”. Of these, text-based retrieval is the most mature and useful, while image-based retrieval using low-level image features usually depends on matching keyframes rather than whole-shots. Automatic detection of video concepts is receiving much attention and as progress is made in this area we will see consequent impact on the quality of video retrieval. In practice it is the combination of these techniques which realises the most useful, and effective, video retrieval as shown by us repeatedly in TRECVid [5].","Title: Semi-automatic semantic enrichment of raw sensor data\nYear: 2007\n\nAbstract: In the XSENSE Project, we gathered a total of 6 biometric sensor data feeds from the participants in our experiments using\n 3 different sensor devices. These readings were taken during 33 experiments where upto 6 users watched a variety of different\n films and their reactions were monitored.","Title: Improved graph cut segmentation by learning a contrast model on the fly.\nYear: 2013\n\nAbstract: This paper describes an extension to the graph cut interactive image segmentation algorithm based on a novel approach to addressing the well known small cut problem. The approach uses a generative contrast model to weight interaction potentials. The model attempts to capture the expected changes in color between adjacent pixels in the unlabeled area of the image using the adjacent pixels in the user interactions as training data. We compare our approach to the standard graph cuts algorithm and show that the contrast model allows a user to achieve a more accurate segmentation with fewer interactions. We additionally introduce a variant of the approach based on superpixels that further enhances performance but reduces computational complexity to ensure instant feedback for optimal user experience.","Title: Smart multi-modal marine monitoring via visual analysis and data fusion\nYear: 2013\n\nAbstract: Estuaries and coastal areas contain increasingly exploited resources that need to be monitored, managed and protected efficiently and effectively. This requires access to reliable and timely data and management decisions must be based on analysis of collected data to avoid or limit negative impacts. Visually supported multi-modal sensing and data fusion offer attractive possibilities for such arduous tasks. In this paper, we demonstrate how an in-situ sensor network can be enhanced with the use of contextual image data. We assimilate and alter a state-of-the-art background modelling technique from the image processing domain in order to detect turbidity spikes in water quality sensor measurements automatically. We then combine this with visual sensing to identify abnormal events that are not caused by local activities. The system can potentially assist those charged with monitoring large scale ecosystems, combining real-time analytics with improved efficiency and effectiveness.","Title: Using segmented objects in ostensive video shot retrieval\nYear: 2005\n\nAbstract: This paper presents a system for video shot retrieval in which shots are retrieved based on matching video objects using a combination of colour, shape and texture. Rather than matching on individual objects, our system supports sets of query objects which in total reflect the user's object-based information need. Our work also adapts to a shifting user information need by initiating the partitioning of a user's search into two or more distinct search threads, which can be followed by the user in sequence. This is an automatic process which maps neatly to the ostensive model for information retrieval in that it allows a user to place a virtual checkpoint on their search, explore one thread or aspect of their information need and then return to that checkpoint to then explore an alternative thread. Our system is fully functional and operational and in this paper we illustrate several design decisions we have made in building it.","Title: 3DLife - Bringing the Media Internet to Life.\nYear: 2013\n\nAbstract: The 3DLife EU FP7 Network of Excellence focuses on stimulating joint research and integrating leading European research groups to create a long-term integration of critical mass for innovation of currently fragmented research addressing media Internet. It fosters the creation of sustainable and long-term relationships between existing national research groups and lay the foundations for a Virtual Centre of Excellence in 3D media Internet - EMC2. This is a summary of 3DLife’s missions as well as its achievements in the last three years.","Title: 3D Estimation and Visualization of Motion in a Multicamera Network for Sports.\nYear: 2011\n\nAbstract: In this work, we develop image processing and computer vision techniques for visually tracking a tennis ball, in 3D, on a court instrumented with multiple low-cost IP cameras. The technique first obtains 2D ball tracking data from each camera view using 2D object tracking methods. Next, an automatic feature-based video synchronization method is applied. This technique uses the extracted 2D ball information from two or more camera views, plus camera calibration information. In order to find 3D trajectory, the temporal 3D locations of the ball is estimated using triangulation of correspondent 2D locations obtained from automatically synchronized videos. Furthermore, in order to improve the continuity of the tracked 3D ball during times when no two cameras have overlapping views of the ball location, we incorporate a physics-based trajectory model into the system. The resultant 3D ball tracks are then visualized in a virtual 3D graphical environment. Finally, we quantify the accuracy of our system in terms of reprojection error.","Title: Effects of environmental colour on mood: a wearable LifeColour capture device\nYear: 2010\n\nAbstract: Colour is everywhere in our daily lives and impacts things like our mood, yet we rarely take notice of it. One method of capturing and analysing the predominant colours that we encounter is through visual lifelogging devices such as the SenseCam. However an issue related to these devices is the privacy concerns of capturing image level detail. Therefore in this work we demonstrate a hardware prototype wearable camera that captures only one pixel - of the dominant colour prevelant in front of the user, thus circumnavigating the privacy concerns raised in relation to lifelogging. To simulate whether the capture of dominant colour would be sufficient we report on a simulation carried out on 1.2 million SenseCam images captured by a group of 20 individuals. We compare the dominant colours that different groups of people are exposed to and show that useful inferences can be made from this data. We believe our prototype may be valuable in future experiments to capture colour correlated associated with an individual's mood.","Title: Persistent homology for 3d reconstruction evaluation\nYear: 2012\n\nAbstract: Space or voxel carving is a non-invasive technique that is used to produce a 3D volume and can be used in particular for the reconstruction of a 3D human model from images captured from a set of cameras placed around the subject. In [1], the authors present a technique to quantitatively evaluate spatially carved volumetric representations of humans using a synthetic dataset of typical sports motion in a tennis court scenario, with regard to the number of cameras used. In this paper, we compute persistent homology over the sequence of chain complexes obtained from the 3D outcomes with increasing number of cameras. This allows us to analyze the topological evolution of the reconstruction process, something which as far as we are aware has not been investigated to date.","Title: Associating characters with events in films\nYear: 2007\n\nAbstract: The work presented here combines the analysis of a film's audiovisual features with the analysis of an accompanying audio description. Specifically, we describe a technique for semantic-based indexing of feature films that associates character names with meaningful events. The technique fuses the results of event detection based on audiovisual features with the inferred on-screen presence of characters, based on an analysis of an audio description script. In an evaluation with 215 events from 11 films, the technique performed the character detection task with Precision = 93% and Recall = 71%. We then go on to show how novel access modes to film content are enabled by our analysis. The specific examples illustrated include video retrieval via a combination of event-type and character name and our first steps towards visualization of narrative and character interplay based on characters occurrence and co-occurrence in events.","Title: Considerations for a touchscreen visual lifelog\nYear: 2011\n\nAbstract: In this paper we describe the design considerations for a touchscreen visual lifelog browser. Visual lifelogs are large collections of photographs which represent a person's experiences. Lifelogging devices, such as the wearable camera known as SenseCam, can record thousands of images per day. Utilizing the approach of event segmentation to organize and present these images, we have designed an interface to present lifelog collections for touchscreen interaction, thus increasing accessibility for users.","Title: Automatically selecting shots for action movie trailers\nYear: 2006\n\nAbstract: Movie trailers, or previews, are an important method of advertising movies. They are extensively shown before movies in cinemas, as well as on television and increasingly, over the Internet. Making a trailer is a creative process, in which a number of shots from a movie are selected in order to entice a viewer in to paying to see the full movie. Thus, the creation of these trailers is an integral part in the promotion of a movie. Action movies in particular rely on trailers as a form of advertising as it is possible to show short, exciting portions of an action movie, which are likely to appeal to the target audience. This paper presents an approach which automatically selects shots from action movies in order to assist in the creation of trailers. A set of audiovisual features are extracted that aim to model the characteristics of shots typically present in trailers, and a support vector machine is utilised in order to select the relevant shots. The approach taken is not particularly novel but the results show that the process may be used in order to ease the trailer creation process or to facilitate the creation of variable length, or personalised trailers.","Title: Pre-Classification For Automatic Image Orientation\nYear: 2006\n\nAbstract: In this paper, we propose a novel method for automatic orientation of digital images. The approach is based on exploiting the properties of local statistics of natural scenes. In this way, we address some of the difficulties encountered in previous works in this area. The main contribution of this paper is to introduce a pre-classification step into carefully defined categories in order to simplify subsequent orientation detection. The proposed algorithm was tested on 9068 images and compared to existing state of the art in the area. Results show a significant improvement over previous works.","Title: Balancing the power of multimedia information retrieval and usability in designing interactive tv\nYear: 2008\n\nAbstract: Steady progress in the field of multimedia information retrieval (MMIR) promises a useful set of tools that could provide new usage scenarios and features to enhance the user experience in today's digital media applications. In the interactive TV domain, the simplicity of interaction is more crucial than in any other digital media domain and ultimately determines the success or otherwise of any new applications. Thus when integrating emerging tools like MMIR into interactive TV, the increase in interface complexity and sophistication resulting from these features can easily reduce its actual usability. In this paper we describe a design strategy we developed as a result of our efforts in balancing the power of emerging multimedia information retrieval techniques and maintaining the simplicity of the interface in interactive TV. By providing multiple levels of interface sophistication in increasing order as a viewer repeatedly presses the same button on their remote control, we provide a layered interface that can accommodate viewers requiring varying degrees of power and simplicity. A series of screen shots from the system we have actually developed and built illustrates how this is achieved.","Title: Tennissense: A Multi-Modal Sensing Platform For Sport\nYear: 2009\n\nAbstract: The evolution of the World-Wide Web to the Sensor Web is providing an unprecedented opportunity to develop novel applications in a variety of domains. In this article we describe our work on multi-modal sensing for sport.","Title: A user-centered approach to rushes summarisation via highlight-detected keyframes\nYear: 2007\n\nAbstract: We present our keyframe-based summary approach for BBC Rushes video as part of the TRECVid Summarisation benchmark evaluation carried out in 2007. We outline our approach to summarisation that uses video processing for feature extraction and is informed by human factors considerations for summary presentation. Based on the performance of our generated summaries as reported by NIST, we subsequently undertook detailed failure analysis of our approach. The findings of this investigation as well as recommendations for alterations to our keyframe-based summary generation method, and the evaluation methodology for Rushes summaries in general, are detailed within this paper.","Title: User-Feedback on a Feature-Rich Photo Organiser\nYear: 2008\n\nAbstract: As the proliferation of digital photography increases, the software used to manage our increasingly large collections of digital photos becomes ever more important. In this paper we present the findings of a study which investigates how people view and interact with a set of photo management features. Specifically, a group of users are set the task of managing their own photos using a system built to encompass a wide range of photo organization functionality. They are then quizzed about their experiences in terms of their feature preferences, the general usability of the system, and other suggestions/requirements. Given these opinions, a basic estimation is then formed on what they like/dislike about the various aspects of the system, towards obtaining a more learned understanding of how we may develop a photo organizer that is optimal in terms of user satisfaction.","Title: Online Television Library: Organisation And Content Browsing For General Users\nYear: 2001\n\nAbstract: This paper describes the organisational and playback features of Fischlar, a digital video library that allows users to record, browse and watch television programmes online. Programmes that can be watched acid recorded are organised by personal recommendations, genre classifications, name and other attributes for access by general television users. Motivations and interactions of users with online television libraries are outlined and they are also supported by personalised library access, categorised programmes, a combined player browser with content viewing history and content marks. The combined player browser supports a user who watches a programme on different occasions in a non-sequential order.","Title: Enhanced visualisation of dance performance from automatically synchronised multimodal recordings\nYear: 2011\n\nAbstract: The Huawei/3DLife Grand Challenge Dataset provides multimodal recordings of Salsa dancing, consisting of audiovisual streams along with depth maps and inertial measurements. In this paper, we propose a system for augmented reality-based evaluations of Salsa dancer performances. An essential step for such a system is the automatic temporal synchronisation of the multiple modalities captured from different sensors, for which we propose efficient solutions. Furthermore, we contribute modules for the automatic analysis of dance performances and present an original software application, specifically designed for the evaluation scenario considered, which enables an enhanced dance visualisation experience, through the augmentation of the original media with the results of our automatic analyses.","Title: An Evaluation of Local Action Descriptors for Human Action Classification in the Presence of Occlusion\nYear: 2014\n\nAbstract: This paper examines the impact that the choice of local descriptor has on human action classifier performance in the presence of static occlusion. This question is important when applying human action classification to surveillance video that is noisy, crowded, complex and incomplete. In real-world scenarios, it is natural that a human can be occluded by an object while carrying out different actions. However, it is unclear how the performance of the proposed action descriptors are affected by the associated loss of information. In this paper, we evaluate and compare the classification performance of the state-of-art human local action descriptors in the presence of varying degrees of static occlusion. We consider four different local action descriptors: Trajectory (TRAJ), Histogram of Orientation Gradient (HOG), Histogram of Orientation Flow (HOF) and Motion Boundary Histogram (MBH). These descriptors are combined with a standard bag-of-features representation and a Support Vector Machine classifier for action recognition. We investigate the performance of these descriptors and their possible combinations with respect to varying amounts of artificial occlusion in the KTH action dataset. This preliminary investigation shows that MBH in combination with TRAJ has the best performance in the case of partial occlusion while TRAJ in combination with MBH achieves the best results in the presence of heavy occlusion.","Title: Identifying Different Settings in a Visual Diary\nYear: 2008\n\nAbstract: We describe an approach to identifying specific settings in large collections of photographs corresponding to a visual diary. An algorithm developed for setting detection should be capable of clustering images captured at the same real world locations (e.g. in the dining room at home, in front of the computer in the office, in the park, etc.). This requires the selection and implementation of suitable methods to identify visually similar backgrounds in images using their visual features. The goal of the work reported here is to automatically detect settings in images taken over a single week. We achieve this using Scale Invariant Feature Transform (SIFT) features and X-means clustering. In addition, we also explore how the use of location based metadata can aid this process.","Title: Motion Synthesis for Sports Using Unobtrusive Lightweight Body-Worn and Environment Sensing.\nYear: 2013\n\nAbstract: The ability to accurately achieve performance capture of athlete motion during competitive play in near real-time promises to revolutionize not only broadcast sports graphics visualization and commentary, but also potentially performance analysis, sports medicine, fantasy sports and wagering. In this paper, we present a highly portable, non-intrusive approach for synthesizing human athlete motion in competitive game-play with lightweight instrumentation of both the athlete and field of play. Our data-driven puppetry technique relies on a pre-captured database of short segments of motion capture data to construct a motion graph augmented with interpolated motions and speed variations. An athlete's performed motion is synthesized by finding a related action sequence through the motion graph using a sparse set of measurements from the performance, acquired from both worn inertial and global location sensors. We demonstrate the efficacy of our approach in a challenging application scenario, with a high-performance tennis athlete wearing one or more lightweight body-worn accelerometers and a single overhead camera providing the athlete's global position and orientation data. However, the approach is flexible in both the number and variety of input sensor data used. The technique can also be adopted for searching a motion graph efficiently in linear time in alternative applications.","Title: Sensor node localisation using a stereo camera rig\nYear: 2007\n\nAbstract: In this paper, we use stereo vision processing techniques to detect and localise sensors used for monitoring simulated environmental events within an experimental sensor network testbed. Our sensor nodes communicate to the camera through patterns emitted by light emitting diodes (LEDs). Ultimately, we envisage the use of very low-cost, low-power, compact microcontroller-based sensing nodes that employ LED communication rather than power hungry RF to transmit data that is gathered via existing CCTV infrastructure. To facilitate our research, we have constructed a controlled environment where nodes and cameras can be deployed and potentially hazardous chemical or physical plumes can be introduced to simulate environmental pollution events in a controlled manner. In this paper we show how 3D spatial localisation of sensors becomes a straightforward task when a stereo camera rig is used rather than a more usual 2D CCTV camera.","Title: A system for event-based film browsing\nYear: 2006\n\nAbstract: The recent past has seen a proliferation in the amount of digital video content being created and consumed. This is perhaps being driven by the increase in audiovisual quality, as well as the ease with which production, reproduction and consumption is now possible. The widespread use of digital video, as opposed its analogue counterpart, has opened up a plethora of previously impossible applications. This paper builds upon previous work that analysed digital video, namely movies, in order to facilitate presentation in an easily navigable manner. A film browsing interface, termed the MovieBrowser, is described, which allows users to easily locate specific portions of movies, as well as to obtain an understanding of the filming being perused. A number of experiments which assess the system's performance are also presented.","Title: Security Considerations and Key Negotiation Techniques for Power Constrained Sensor Networks\nYear: 2006\n\nAbstract: Sensor networks are becoming increasingly important for a wide variety of applications including environmental monitoring, building safety and emergency relief services. A typical sensor network consists of a large number of small, low-power, low-cost nodes that form a self-organized network using wireless peer-to-peer communication. Because sensor networks pose unique constraints on their operation, traditional security techniques used by conventional networks cannot be applied. In this paper we consider the operational issues and security threats to sensor networks. We discuss the state of the art in terms of sensor network security and we examine the practicality of using efficient elliptic curve algorithms and identity based encryption to deploy a secure sensor network infrastructure. We evaluate the potential for realizing this on low-power, long-life devices by measuring power consumption of the operations needed for key management in a sensor network and thus provide further evidencefor the feasibility of the approach.","Title: Audio-Visual Classification Video Browser\nYear: 2014\n\nAbstract: This paper presents our third participation in the Video Browser Showdown. Building on the experience that we gained while participating in this event, we compete in the 2014 showdown with a more advanced browsing system based on incorporating several audio-visual retrieval techniques. This paper provides a short overview of the features and functionality of our new system.","Title: User evaluation of Físchlár-News: An automatic broadcast news delivery system\nYear: 2006\n\nAbstract: Technological developments in content-based analysis of digital video information are undergoing much progress, with ideas for fully automatic systems now being proposed and demonstrated. Yet because we do not yet have robust operational video retrieval systems that can be deployed and used, the usual HCI practise of conducting a usage study and an informed iterative system design is thus not possible. Físchlár-News is one of the first automatic, content-based broadcast news analysis and archival systems that process broadcast news video so that users can search, browse, and play it in an easy-to-use manner with a conventional web browser. The system incorporates a number of state-of-the-art research components, some of which are not yet considered mature technology, yet it has been built to be robust enough to be deployed to users who are interested in access to daily news throughout a university campus. In this article we report and discuss a user-evaluation study conducted with 16 users, each of whom utilized the system freely for a one month period. Results from a detailed qualitative analysis are presented, looking at collected questionnaires, incident diaries, and interaction-log data. The findings suggest that our users employed the system in conjunction with their other news update methods, such as watching TV news at home and browsing online news websites at their workplace, their major concerns being up-to-dateness and coverage of the news content. They tried to accommodate the system to fit their established web browsing habits, and they found local news content and the ability to play self-contained news stories on their desktop as major values of the system. Our study also resulted in a detailed wishlist of new features which will help in the further development of both our and others' systems.","Title: A virtual coaching environment for improving golf swing technique\nYear: 2010\n\nAbstract: As a proficient golf swing is a key element of success in golf, many golfers make significant effort improving their stroke mechanics. In order to help enhance golfing performance, it is important to identify the performance determining factors within the full golf swing. In addition, explicit instructions on specific features in stroke technique requiring alterations must be imparted to the player in an unambiguous and intuitive manner. However, these two objectives are difficult to achieve due to the subjective nature of traditional coaching techniques and the predominantly implicit knowledge players have of their movements. In this work, we have developed a set of visualisation and analysis tools for use in a virtual golf coaching environment. In this virtual coaching studio, the analysis tools allow for specific areas require improvement in a player's 3D stroke dynamics to be isolated. An interactive 3D virtual coaching environment then allows detailed and unambiguous coaching information to be visually imparted back to the player via the use of two virtual human avatars; the first mimics the movements performed by the player; the second takes the role of a virtual coach, performing ideal stroke movement dynamics. The potential of the coaching tool is highlighted in its use by sports science researchers in the evaluation of competing approaches for calculating the X-Factor, a significant performance determining factor for hitting distance in a golf swing.","Title: The colour of life: novel visualisations of population lifestyles\nYear: 2010\n\nAbstract: Colour permeates our daily lives, yet we rarely take notice of it. In this work we utilise the SenseCam (a visual lifelogging tool), to investigate the predominant colours in one million minutes of human life that a group of 20 individuals encounter throughout their normal daily activities. We also compare the colours that different groups of people are exposed to in their typical days. This information is presented in using a novel colour-wheel visualisation which is a new means of illustrating that people are exposed to bright colours over longer durations of time during summer months, and more dark colours during winter months.","Title: InSPeCT: integrated surveillance for port container traffic\nYear: 2011\n\nAbstract: This paper describes a fully-operational content-indexing and management system, designed for monitoring and profiling freight-based vehicular traffic in a seaport environment. The 'InSPeCT' system captures video footage of passing vehicles and uses tailored OCR to index the footage according to vehicle license plates and freight codes. In addition to real-time functionality such as alerting, the system provides advanced search techniques for the efficient retrieval of records, where each vehicle is profiled according to multi-angled video, context information, and links to external information sources. Currently being piloted at a busy national seaport, the feedback from port officials indicates the system to be extremely useful in supplementing their existing transportation-security structures.","Title: Local Wavelet Features for Statistical Object Classification and Localization\nYear: 2010\n\nAbstract: This article presents a system for texture-based probabilistic classification and localization of 3D objects in 2D digital images and discusses selected applications.","Title: Event detection in pedestrian detection and tracking applications\nYear: 2007\n\nAbstract: In this paper, we present a system framework for event detection in pedestrian and tracking applications. The system is built upon a robust computer vision approach to detecting and tracking pedestrians in unconstrained crowded scenes. Upon this framework we propose a pedestrian indexing scheme and suite of tools for detecting events or retrieving data from a given scenario.","Title: Breathing Feedback System with Wearable Textile Sensors\nYear: 2010\n\nAbstract: Breathing exercises form an essential part of the treatment for respiratory illnesses such as cystic fibrosis. Ideally these exercises should be performed on a daily basis. This paper presents an interactive system using a wearable textile sensor to monitor breathing patterns. A graphical user interface provides visual real-time feedback to patients. The aim of the system is to encourage the correct performance of prescribed breathing exercises by monitoring the rate and the depth of breathing. The system is straight forward to use, low-cost and can be installed easily within a clinical setting or in the home. Monitoring the user with a wearable sensor gives real-time feedback to the user as they perform the exercise, allowing them to perform the exercises independently. There is also potential for remote monitoring where the user’s overall performance over time can be assessed by a clinician.","Title: Vision-Based Analysis Of Pedestrian Traffic Data\nYear: 2008\n\nAbstract: Reducing traffic congestion has become a major issue within urban environments. Traditional approaches, such as increasing road sizes, may prove impossible in certain scenarios, such as city centres, or ineffectual if current predictions of large growth in world traffic volumes hold true. An alternative approach lies with increasing the management efficiency of pre-existing infrastructure and public transport systems through the use of Intelligent Transportation Systems (ITS). In this paper, we focus on the requirement of obtaining robust pedestrian traffic flow data within these areas. We propose the use of a flexible and robust stereo-vision pedestrian detection and tracking approach as a basis for obtaining this information. Given this framework, we propose the use of a pedestrian indexing scheme and a suite of tools, which facilitates the declaration of user-defined pedestrian events or requests for specific statistical traffic: flow data. The detection of the required events or the constant flow of statistical information can be incorporated into a variety of ITS solutions for applications in traffic management, public transport systems and urban planning.","Title: Interactive experiments in object-based retrieval\nYear: 2006\n\nAbstract: Object-based retrieval is a modality for video retrieval based on segmenting objects from video and allowing end-users to use these objects as part of querying. In this paper we describe an empirical TRECVid-like evaluation of object-based search, and compare it with a standard image-based search into an interactive experiment with 24 search topics and 16 users each performing 12 search tasks on 50 hours of rushes video. This experiment attempts to measure the impact of object-based search on a corpus of video where textual annotation is not available.","Title: Low Complexity Video Compression Using Moving Edge Detection Based on DCT Coefficients\nYear: 2009\n\nAbstract: In this paper, we propose a new low complexity video compression method based on detecting blocks containing moving edges using only DCT coefficients. The detection, whilst being very efficient, also allows efficient motion estimation by constraining the search process to moving macro-blocks only. The encoders PSNR is degraded by 2dB compared to H.264/AVC inter for such scenarios, whilst requiring only 5% of the execution time. The computational complexity of our approach is comparable to that of the DISCOVER codec which is the state of the art low complexity distributed video coding. The proposed method finds blocks with moving edge blocks and processes only selected blocks. The approach is particularly suited to surveillance type scenarios with a static camera.","Title: An interactive and multi-level framework for summarising user generated videos\nYear: 2009\n\nAbstract: We present an interactive and multi-level abstraction framework for user-generated video (UGV) summarisation, allowing a user the flexibility to select a summarisation criterion out of a number of methods provided by the system. First, a given raw video is segmented into shots, and each shot is further decomposed into sub-shots in line with the change in dominant camera motion. Secondly, principal component analysis (PCA) is applied to the colour representation of the collection of sub-shots, and a content map is created using the first few components. Each sub-shot is represented with a \"footprint\" on the content map, which reveals its content significance (coverage) and the most dynamic segment. The final stage of abstraction is devised in a user-assisted manner whereby a user is able to specify a desired summary length, with options to interactively perform abstraction at different granularity of visual comprehension. The results obtained show the potential benefit in significantly alleviating the burden of laborious user intervention associated with conventional video editing/browsing.","Title: Complexity adaptation in H.264/AVC video coder for static cameras.\nYear: 2009\n\nAbstract: H.264/AVC uses variable block size motion estimation (VBSME) to improve coding gain. However, its complexity is significant and fixed regardless of the required quality or of the scene characteristics. In this paper, we propose an adaptive complexity algorithm based on using the Walsh Hadamard Transform (WHT). VBS automatic partition and skip mode detection algorithms also are proposed. Experimental results show that 70% - 5% of the computation of H.264/AVC is required to achieve the same PSNR.","Title: Semantic Analysis of Field Sports Video using a Petri-Net of Audio-Visual Concepts\nYear: 2009\n\nAbstract: The most common approach to automatic summarization and highlight detection in sports video is to train an automatic classifier to detect semantic highlights based on occurrences of low-level features such as action replays, excited commentators or changes in a scoreboard. We propose an alternative approach based on the detection of perception concepts (PCs) and the construction of Petri-Nets, which can be used for both semantic description and event detection within sports videos. Low-level algorithms to detect PCs using visual, aural and motion characteristics are proposed, and a series of Petri-Nets composed of PCs is formally defined to describe video content. We call this a perception concept network–Petri-Net (PCN–PN) model. Using PCN–PNs, personalized high-level semantic descriptions of video highlights can be facilitated and queries on high-level semantics can be achieved. A particular strength of this framework is that we can easily build semantic detectors based on PCN–PNs to search within sports videos and locate interesting events. Experimental results based on recorded sports video data across three types of sports games (soccer, basketball and rugby), and each from multiple broadcasters, are used to illustrate the potential of this framework.","Title: Blending real with virtual in 3DLife\nYear: 2013\n\nAbstract: Part of 3DLife's major goal to bring the 3D media Internet to life, concerns the development and wide-spread distribution of online tele-immersive (TI) virtual environments. As the techniques powering challenging tasks for user reconstruction and activity tracking within a virtual environment are maturing, along with consumer-grade availability of specialized hardware, this paper focuses on the simple practices used to make real-time tele-immersion within a networked virtual world a reality.","Title: Low-cost creation of a 3D interactive museum exhibition\nYear: 2011\n\nAbstract: We present a demonstration of a multi-sensory virtual experience that accurately reflects the experience of a real visit to a museum. We have developed a 3D interactive digital museum exhibition corresponding to a photo-realistic 3D reconstruction of the Iconic Treasures exhibition at the National Museum of Ireland's archaeology building. Users can explore the 3D virtual environment and interact with the displays by accessing high resolution photographs and historical descriptions of the artefacts. This demo will showcase the experience on a 3D laptop with the use of active shutter LCD glasses to create an immersive experience. A key aspect of the demonstration is that it was developed using low-cost or freely available OTS tools wherever possible putting the creation of such digital exhibitions within reach of even modest budgets.","Title: An Investigation into Feature Effectiveness for Multimedia Hyperlinking\nYear: 2014\n\nAbstract: The increasing amount of archival multimedia content available online is creating increasing opportunities for users who are interested in exploratory search behaviour such as browsing. The user experience with online collections could therefore be improved by enabling navigation and recommendation within multimedia archives, which can be supported by allowing a user to follow a set of hyperlinks created within or across documents. The main goal of this study is to compare the performance of different multimedia features for automatic hyperlink generation. In our work we construct multimedia hyperlinks by indexing and searching textual and visual features extracted from the blip.tv dataset. A user-driven evaluation strategy is then proposed by applying the Amazon Mechanical Turk (AMT) crowdsourcing platform, since we believe that AMT workers represent a good example of \\\"real world\\\" users. We conclude that textual features exhibit better performance than visual features for multimedia hyperlink construction. In general, a combination of ASR transcripts and metadata provides the best results.","Title: The AXES PRO video search system\nYear: 2013\n\nAbstract: We demonstrate a multimedia content information retrieval engine developed for audiovisual digital libraries targeted at media professionals. It is the first of three multimedia IR systems being developed by the AXES project. The system brings together traditional text IR and state-of-the-art content indexing and retrieval technologies to allow users to search and browse digital libraries in novel ways. Key features include: metadata and ASR search and filtering, on-the-fly visual concept classification (categories, faces, places, and logos), and similarity search (instances and faces).","Title: Towards Automated Robust Vision-Based Surveillance\nYear: 2008\n\nAbstract: COST is one of the longest‐running instruments funded by the EU RTD Framework Program. The members of the COST 292 action (see: http://www.cost292.org/) have a long tradition of involvement in WIAMIS, dating back to the establishment of this event. Since 2005, the action has been invited to organize a special session and this tradition was continued for WIAMIS 2008. This year, the special session focused on a subset of the broad research remit of the action. Specifically, the session targets research in the field of automated visual surveillance. This focus reflects a growing interest within COST 292 participants in this increasingly important area. The goal of this special session is to help bring together researchers working on this topic, both within COST 292 and beyond, with a view to stimulating future collaborative research in this area. The widely circulated call for papers targeted submissions on a broad range of topics covered by the above mentioned focus, including visual computation, event and activity modelingand analysis, multiple stream analysis, architectures, indexing and storage, coding and applications. All papers were peer reviewed by at least three reviewers drawn from a combination of the WIAMIS Technical Program Committee and a special Program Subcommittee set up specifically for this special session. Acceptance criteria considered overall quality as well as relevance to the topics of the special session. In the end, just 5 papers were accepted for oral presentation. The accepted papers address scene modeling, event detection, object recognition (human and non‐human) and fusion of multiple complementary data sources.","Title: Measuring the impact of temporal context on video retrieval\nYear: 2008\n\nAbstract: In this paper we describe the findings from the K-Space interactive video search experiments in TRECVid 2007, which examined the effects of including temporal context in video retrieval. The traditional approach to presenting video search results is to maximise recall by offering a user as many potentially relevant shots as possible within a limited amount of time. 'Context'-oriented systems opt to allocate a portion of the results presentation space to providing additional contextual cues about the returned results. In video retrieval these cues often include temporal information such as a shot's location within the overall video broadcast and/or its neighbouring shots. We developed two interfaces with identical retrieval functionality in order to measure the effects of such context on user performance. The first system had a 'recall-oriented' interface, where results from a query were presented as a ranked list of shots. The second was 'context-oriented', with results presented as a ranked list of broadcasts. 10 users participated in the experiments, of which 8 were novices and 2 experts. Participants completed a number of retrieval topics using both the recall-oriented and context-oriented systems.","Title: Toward automated evaluation of interactive segmentation\nYear: 2011\n\nAbstract: We previously described a system for evaluating interactive segmentation by means of user experiments (McGuinness and O'Connor, 2010) [1]. This method, while effective, is time-consuming and labor-intensive. This paper aims to make evaluation more practicable by investigating if it is feasible to automate user interactions. To this end, we propose a general algorithm for driving the segmentation that uses the ground truth and current segmentation error to automatically simulate user interactions. We investigate four strategies for selecting which pixels will form the next interaction. The first of these is a simple, deterministic strategy; the remaining three strategies are probabilistic, and focus on more realistically approximating a real user. We evaluate four interactive segmentation algorithms using these strategies, and compare the results with our previous user experiment-based evaluation. The results show that automated evaluation is both feasible and useful.","Title: MyPlaces: detecting important settings in a visual diary\nYear: 2008\n\nAbstract: We describe a novel approach to identifying specific settings in large collections of passively captured images corresponding to a visual diary. An algorithm developed for setting detection should be capable of detecting images captured at the same real world locations (e.g. in the dining room at home, in front of the computer in the office, in the park, etc.). This requires the selection and implementation of suitable methods to identify visually similar backgrounds in images using their visual features. We use a Bag of Keypoints approach. This method is based on the sampling and subsequent vector quantization of multiple image patches. The image patches are sampled and described using Scale Invariant Feature Transform (SIFT) features. We compare three different classifiers, K Nearest Neighbour (KNN), Multiclass Linear Perceptron (MLP), and Support Vector Machine (SVM), and present results for classifying ten different settings across one week's worth of images. Our results demonstrate that the method produces good classification accuracy even without exploiting geometric or context based information. We also describe an early prototype of a visual diary browser that integrates the classification results.","Title: Investigation of Image Models for Landmark Classification.\nYear: 2009\n\nAbstract: One commonly used approach to scene localization and landmark recognition is to match an input image against a large annotated database of images using local image features. However problems exist with these approaches relating to memory constraints and the processing time required to compare high dimensional image feature vectors in a very large scale database.\\par We investigate a new landmark classification technique which takes advantage of the fact that there is considerable overlap in visually similar images of landmarks in any large public photo repository. A large number of images containing landmarks are clustered into visually similar clusters. Classification models are then implemented and trained based on global histograms of interest point features from these clusters to create models which can be used for robust real-time accurate classification of images containing these landmarks. We also investigate different techniques for the creation of these classification models to ascertain how best to guarantee a high level of robustness, accuracy and speed.","Title: Robust pedestrian detection and tracking in crowded scenes\nYear: 2009\n\nAbstract: In this paper, a robust computer vision approach to detecting and tracking pedestrians in unconstrained crowded scenes is presented. Pedestrian detection is performed via a 3D clustering process within a region-growing framework. The clustering process avoids using hard thresholds by using bio-metrically inspired constraints and a number of plan-view statistics. Pedestrian tracking is achieved by formulating the track matching process as a weighted bipartite graph and using a Weighted Maximum Cardinality Matching scheme. The approach is evaluated using both indoor and outdoor sequences, captured using a variety of different camera placements and orientations, that feature significant challenges in terms of the number of pedestrians present, their interactions and scene lighting conditions. The evaluation is performed against a manually generated groundtruth for all sequences. Results point to the extremely accurate performance of the proposed approach in all cases.","Title: Kinect vs. Low-cost Inertial Sensing for Gesture Recognition\nYear: 2014\n\nAbstract: In this paper, we investigate efficient recognition of human gestures / movements from multimedia and multimodal data, including the Microsoft Kinect and translational and rotational acceleration and velocity from wearable inertial sensors. We firstly present a system that automatically classifies a large range of activities (17 different gestures) using a random forest decision tree. Our system can achieve near real time recognition by appropriately selecting the sensors that led to the greatest contributing factor for a particular task. Features extracted from multimodal sensor data were used to train and evaluate a customized classifier. This novel technique is capable of successfully classifying various gestures with up to 91 % overall accuracy on a publicly available data set. Secondly we investigate a wide range of different motion capture modalities and compare their results in terms of gesture recognition accuracy using our proposed approach. We conclude that gesture recognition can be effectively performed by considering an approach that overcomes many of the limitations associated with the Kinect and potentially paves the way for low-cost gesture recognition in unconstrained environments.","Title: Stopping region-based image segmentation at meaningful partitions\nYear: 2007\n\nAbstract: This paper proposes a new stopping criterion for automatic image segmentation based on region merging. The criterion is dependent on image content itself and when combined with the recently proposed approaches to syntactic segmentation can produce results aligned with the most salient semantic regions/objects present in the scene across heterogeneous image collections. The method identifies a single iteration from the merging process as the stopping point, based on the evolution of an accumulated merging cost during the complete merging process. The approach is compared to three commonly used stopping criteria: (i) required number of regions, (ii) value of the least link cost, and (iii) Peak Signal to Noise Ratio (PSNR). For comparison, the stopping criterion is also evaluated for a segmentation approach that does not use syntactic extensions. All experiments use a manually generated segmentation ground truth and spatial accuracy measures. Results show that the proposed stopping criterion improves segmentation performance towards reflecting real-world scene content when integrated into a syntactic segmentation framework.","Title: Automatic TV Advertisement Detection from MPEG Bitstream\nYear: 2001\n\nAbstract: The Centre for Digital Video Processing at Dublin City University conducts concentrated research and development in the area of digital video management. The current stage of development is demonstrated on our Web-based digital video system called Fı́schlár (Proceedings of the Content based Multimedia Information Access, RIAO 2000, Vol. 2, Paris, France, 12–14 April 2000, p. 1390), which provides for efficient recording, analysing, browsing and viewing of digitally captured television programmes. Advertisement breaks during or between television programmes are typically recognised by a series of ‘black’ video frames simultaneously accompanying a depression in audio volume which separate each advertisement from one another by recurrently occurring before and after each individual advertisement. It is the regular prevalence of these flags that enables automatic differentiation between what is programme and what is a commercial break. This paper reports on the progress made in the development of this idea into an advertisement detector system that automatically detects the commercial breaks from the bitstream of digitally captured television broadcasts.","Title: Keyframe detection in visual lifelogs\nYear: 2008\n\nAbstract: The SenseCam is a wearable camera that passively captures images. Therefore, it requires no conscious effort by a user in taking a photo. A Visual Diary from such a source could prove to be a valuable tool in assisting the elderly, individuals with neurodegenerative diseases, or other traumas. One issue with Visual Lifelogs is the large volume of image data generated. In previous work, we segmented a day's worth of images into more manageable segments, i.e. into distinct events or activities. However, each event could still consist of 80-100 images, thus, in this paper we propose a novel approach to selecting the key images within an event using a combination of MPEG-7 and Scale Invariant Feature Transform (SIFT) features.","Title: Tools for User Interaction in Immersive Environments\nYear: 2014\n\nAbstract: REVERIE REal and Virtual Engagement in Realistic Immersive Environments is a large scale collaborative project co-funded by the European Commission targeting novel research in the general domain of Networked Media and Search Systems. The project aims to bring about a revolution in 3D media and virtual reality by developing technologies for safe, collaborative, online environments that can enable realistic interpersonal communication and interaction in immersive environments. To date, project partners have been developing component technologies for a variety of functionalities related to the aims of REVERIE prior to integration into an end-to-end system. In this demo submission, we first introduce the project in general terms, outlining the high-level concept and vision before briefly describing the suite of demonstrations that we intend to present at MMM 2014.","Title: Mo Músaem Fíorúil: A Web-Based Search and Information Service for Museum Visitors\nYear: 2008\n\nAbstract: We describe the prototype of an interactive, web-based, museum artifact search and information service. Mo Músaem Fíorúil clusters and indexes images of museum artifacts taken by visitors to the museum where the images are captured using a passive capture device such as Microsoft's SenseCam [1]. The system also matches clustered artifacts to images of the same artifact from the museums official photo collection and allows the user to view images of the same artifact taken by other visitors to the museum. This matching process potentially allows the system to provide more detailed information about a particular artifact to the user based on their inferred preferences, thereby greatly enhancing the user's overall museum experience. In this work, we introduce the system and describe, in broad terms, it's overall functionality and use. Using different image sets of artificial museum objects, we also describe experiments and results carried out in relation to the artifact matching component of the system.","Title: Towards Fully Automatic Image Segmentation Evaluation\nYear: 2008\n\nAbstract: Spatial region (image) segmentation is a fundamental step for many computer vision applications. Although many methods have been proposed, less work has been done in developing suitable evaluation methodologies for comparing different approaches. The main problem of general purpose segmentation evaluation is the dilemma between objectivity and generality. Recently, figure ground segmentation evaluation has been proposed to solve this problem by defining an unambiguous ground truth using the most salient foreground object. Although the annotation of a single foreground object is less complex than the annotation of all regions within an image, it is still quite time consuming, especially for videos. A novel framework incorporating background subtraction for automatic ground truth generation and different foreground evaluation measures is proposed, that allows to effectively and efficiently evaluate the performance of image segmentation approaches. The experiments show that the objective measures are comparable to the subjective assessment and that there is only a slight difference between manually annotated and automatically generated ground truth.","Title: Pedestrian detection in uncontrolled environments using stereo and biometric information\nYear: 2006\n\nAbstract: A method for pedestrian detection from challenging real world outdoor scenes is presented in this paper. This technique is able to extract multiple pedestrians, of varying orientations and appearances, from a scene even when faced with large and multiple occlusions. The technique is also robust to changing background lighting conditions and effects, such as shadows. The technique applies an enhanced method from which reliable disparity information can be obtained even from untextured homogeneous areas within a scene. This is used in conjunction with ground plane estimation and biometric information,to obtain reliable pedestrian regions. These regions are robust to erroneous areas of disparity data and also to severe pedestrian occlusion, which often occurs in unconstrained scenarios.","Title: Indexing of Fictional Video Content for Event Detection and Summarisation.\nYear: 2007\n\nAbstract: This paper presents an approach to movie video indexing that utilises audiovisual analysis to detect important and meaningful temporal video segments, that we term events. We consider three event classes, corresponding to dialogues, action sequences, and montages, where the latter also includes musical sequences. These three event classes are intuitive for a viewer to understand and recognise whilst accounting for over 90% of the content of most movies. To detect events we leverage traditional filmmaking principles and map these to a set of computable low-level audiovisual features. Finite state machines (FSMs) are used to detect when temporal sequences of specific features occur. A set of heuristics, again inspired by filmmaking conventions, are then applied to the output of multiple FSMs to detect the required events. A movie search system, named MovieBrowser, built upon this approach is also described. The overall approach is evaluated against a ground truth of over twenty-three hours of movie content drawn from various genres and consistently obtains high precision and recall for all event classes. A user experiment designed to evaluate the usefulness of an event-based structure for both searching and browsing movie archives is also described and the results indicate the usefulness of the proposed approach.","Title: Experiencing SenseCam: a case study interview exploring seven years living with a wearable camera\nYear: 2013\n\nAbstract: This paper presents the findings from an interview with CG, an individual who has worn an automated camera, the SenseCam, every day for the past seven years. Of interest to the study were the participant's day-to-day experiences wearing the camera and whether these had changed since first wearing the camera. The findings presented outline the effect that wearing the camera has on his self-identity, relationships and interactions with people in the public. Issues relating to data capture, transfer and retrieval of lifelog images are also identified. These experiences inform us of the long-term effects of digital life capture and how lifelogging could progress in the future.","Title: A Sensing Platform for Physiological and Contextual Feedback to Tennis Athletes\nYear: 2009\n\nAbstract: In this paper we describe our work on creating a multimodal sensing platform for providing feedback to tennis coaches and players. The platform includes a fixed installation around a tennis court consisting of a video camera network and a localisation system as well as wearable sensing technology deployed to individual athletes. We describe the various components of this platform and explain how we can capture synchronised multi-modal sensor data streams for games or training sessions. We then describe the content-based retrieval system we are building to facilitate the development of novel coaching tools. We provide some examples of the queries that the system can support, where these queries are chosen to be suitably expressive so as to reflect a coach’s complex information needs regarding tennis-related performance factors.","Title: Using text search for personal photo collections with the MediAssist system\nYear: 2007\n\nAbstract: The MediAssist system enables organisation and searching of personal digital photo collections based on contextual information, content-based analysis and semi-automatic annotation. One mode of user interaction uses automatically extracted features to create text surrogates for photos, which enables text search of photo collections without manual annotation. Our evaluation shows that this text search facility is effective for known-item search.","Title: SCReen adjusted panoramic effect: SCRAPE\nYear: 2013\n\nAbstract: A Cave Automatic Virtual Environment (CAVE) is an enclosed virtual reality room that uses multiple projectors to display images across its surfaces. It uses one or more computers to synchronise and combine the images and allows users to control virtual worlds using a host of interaction devices. Traditionally, a CAVE is used by a single user at any one time and by utilising some form of motion sensing, the user's head position can be tracked to allow for first virtual perception. The images are then displayed in stereographic 3D in order to complete the virtual reality effect. Professional CAVE installations are expensive and can cost upwards of several hundred thousand euros. This tends to act as a significant barrier to their propagation, however, as the reduction in cost of high specification computers, projectors and graphics cards continues apace, it has sparked a renewed interest in CAVE environments and given rise to the realistic possibility of setting up low cost, amateur CAVEs. Unfortunately, one of the greatest disadvantages of CAVE systems is the lack of inexpensive, easy to use, specialised software. In this paper we present an open source and easy to use CAVE software toolkit called SCReen Adjusted Panoramic Effect or SCRAPE for short. We believe that SCRAPE is the first major piece in a longer-term vision that aims to bring easy to setup, easy to use, portable CAVE systems to all types of non-expert users.","Title: Unsupervised Feature Selection for Detection Using Mutual Information Thresholding\nYear: 2008\n\nAbstract: This paper proposes a method for unsupervised selection of features for detecting important events in a surveillance context. While traditional feature selection requires manually annotated ground truth to choose the best features, we examine the possibility of exploiting the redundancy between a pair of independent data sources for selecting good detection features. Building on our prior work on mutual information thresholding, we show that strong agreement between data sources indicates strong detection performance. Experimental tests, combining visual and audio data, show that the best performing features can be automatically selected by taking advantage of the common information shared by the sensors.","Title: Combining image descriptors to effectively retrieve events from visual lifelogs\nYear: 2008\n\nAbstract: The SenseCam is a wearable camera that passively captures approximately 3,000 images per day, which equates to almost one million images per year. It is used to create a personal visual recording of the wearer's life and generates information which can be helpful as a human memory aid. For such a large amount of visual information to be of any use, it is accepted that it should be structured into \"events\", of which there are about 8,000 in a wearer's average year. In automatically segmenting SenseCam images into events, it will then be useful for users to locate other events similar to a given event e.g. \"what other times was I walking in the park?\", \"show me other events when I was in a restaurant\". On two datasets of 240k and 1.8M images containing topics with a variety of information needs, we evaluate the fusion of MPEG-7, SIFT, and SURF content-based retrieval techniques to address the event search issue. We have found that our proposed fusion approach of MPEG-7 and SURF offers an improvement on using either of those sources or SIFT individually, and we have also shown how a lifelog event is modeled has a large effect on the retrieval performance.","Title: Dublin City University Video Track Experiments for TREC 2001\nYear: 2002\n\nAbstract: Dublin City University participated in the interactive search task and Shot Boundary Detection task* of the TREC Video Track. In the interactive search task experiment thirty people used three different digital video browsers to find video segments matching the given topics. Each user was under a time constraint of six minutes for each topic assigned to them. The purpose of this experiment was to compare video browsers and so a method was developed for combining independent users' results for a topic into one set of results. Collated results based on thirty users are available herein though individual users' and browsers' results are currently unavailable for comparison. Our purpose in participating in this TREC track was to create the ground truth within the TREC framework, which will allow us to do direct browser performance comparisons.","Title: Thermo-visual feature fusion for object tracking using multiple spatiogram trackers\nYear: 2008\n\nAbstract: In this paper, we propose a framework that can efficiently combine features for robust tracking based on fusing the outputs of multiple spatiogram trackers. This is achieved without the exponential increase in storage and processing that other multimodal tracking approaches suffer from. The framework allows the features to be split arbitrarily between the trackers, as well as providing the flexibility to add, remove or dynamically weight features. We derive a mean-shift type algorithm for the framework that allows efficient object tracking with very low computational overhead. We especially target the fusion of thermal infrared and visible spectrum features as the most useful features for automated surveillance applications. Results are shown on multimodal video sequences clearly illustrating the benefits of combining multiple features using our framework.","Title: Team activity recognition in sports\nYear: 2012\n\nAbstract: We introduce a novel approach for team activity recognition in sports. Given the positions of team players from a plan view of the playing field at any given time, we solve a particular Poisson equation to generate a smooth distribution defined on whole playground, termed the position distribution of the team. Computing the position distribution for each frame provides a sequence of distributions, which we process to extract motion features for team activity recognition. The motion features are obtained at each frame using frame differencing and optical flow. We investigate the use of the proposed motion descriptors with Support Vector Machines (SVM) classification, and evaluate on a publicly available European handball dataset. Results show that our approach can classify six different team activities and performs better than a method that extracts features from the explicitly defined positions. Our method is new and different from other trajectory-based methods. These methods extract activity features using the explicitly defined trajectories, where the players have specific positions at any given time, and ignore the rest of the playground. In our work, on the other hand, given the specific positions of the team players at a frame, we construct a position distribution for the team on the whole playground and process the sequence of position distribution images to extract motion features for activity recognition. Results show that our approach is effective.","Title: Experiences of Aiding Autobiographical Memory Using the SenseCam.\nYear: 2012\n\nAbstract: Human memory is a dynamic system that makes accessible certain memories of events based on a hierarchy of information, arguably driven by personal significance. Not all events are remembered, but those that are tend to be more psychologically relevant. In contrast, lifelogging is the process of automatically recording aspects of one's life in digital form without loss of information. In this article we share our experiences in designing computer-based solutions to assist people review their visual lifelogs and address this contrast. The technical basis for our work is automatically segmenting visual lifelogs into events, allowing event similarity and event importance to be computed, ideas that are motivated by cognitive science considerations of how human memory works and can be assisted. Our work has been based on visual lifelogs gathered by dozens of people, some of them with collections spanning multiple years. In this review article we summarize a series of studies that have led to the development of a browser that is based on human memory systems and discuss the inherent tension in storing large amounts of data but making the most relevant material the most accessible.","Title: TRECVid 2006 Experiments at Dublin City University\nYear: 2006\n\nAbstract: In this paper we describe our retrieval system and experiments performed for the automatic search task in TRECVid 2006. We submitted the following six automatic runs: • F A 1 DCU-Base 6: Baseline run using only ASR/MT text features. • F A 2 DCU-TextVisual 2: Run using text and visual features. • F A 2 DCU-TextVisMotion 5: Run using text, visual, and motion features. • F B 2 DCU-Visual-LSCOM 3: Text and visual features combined with concept detectors. • F B 2 DCU-LSCOM-Filters 4: Text, visual, and motion features with concept detectors. • F B 2 DCU-LSCOM-2 1: Text, visual, motion, and concept detectors with negative concepts. The experiments were designed both to study the addition of motion features and separately constructed models for semantic concepts, to runs using only textual and visual features, as well as to establish a baseline for the manually-assisted search runs performed within the collaborative K-Space project and described in the corresponding TRECVid 2006 notebook paper. The results of the experiments indicate that the performance of automatic search can be improved with suitable concept models. This, however, is very topic-dependent and the questions of when to include such models and which concept models should be included, remain unanswered. Secondly, using motion features did not lead to performance improvement in our experiments. Finally, it was observed that our text features, despite displaying a rather poor performance overall, may still be useful even for generic search topics.","Title: TRECVid 2007 Experiments at Dublin City University\nYear: 2007\n\nAbstract: In this paper we describe our retrieval system and experiments performed for the auto- matic search task in TRECVid 2007. We submitted the following six automatic runs: • F A 1 DCU-TextOnly6: Baseline run using only ASR/MT text features. • F A 1 DCU-ImgBaseline4: Baseline visual expert only run, no ASR/MT used. Made use of query-time generation of retrieval expert coefficients for fusion. • F A 2 DCU-ImgOnlyEnt5: Automatic generation of retrieval expert coefficients for fusion at index time. • F A 2 DCU-imgOnlyEntHigh3: Combination of coefficient generation which com- bined the coefficients generated by the query-time approach,and the index-time approach, with greater weight given to the index-time coefficient. • F A 2 DCU-imgOnlyEntAuto2: As above, except that greater weight is given to the query-time coefficient that was generated. • F A 2 DCU-autoMixed1: Query-time expert coefficient generation that used both visual and text experts.","Title: A user-centric system for home movie summarisation\nYear: 2011\n\nAbstract: In this paper we present a user-centric summarisation system that combines automatic visual-content analysis with user-interface design features as a practical method for home movie summarisation. The proposed summarisation system is designed in such a manner that the video segmentation results generated by the automatic content analysis tools are further subject to refinement through the use of an intuitive user-interface so that the automatically created summaries can be effectively tailored to each individual's personal need. To this end, we study a number of content analysis techniques to facilitate the efficient computation of video summaries, and more specifically emphasise the need for employing an efficient and robust optical flow field computation method for sub-shot segmentation in home movies. Due to the subjectivity of video summarisation and the inherent challenges associated with automatic content analysis, we propose novel user-interface design features as a means to enable the creation of meaningful home movie summaries in a simple manner. The main features of the proposed summarisation system include the ability to automatically create summaries of different visual comprehension, interactively defining the target length of the desired summary, easy and interactive viewing of the content in terms of a storyboard, and manual refinement of the boundaries of the automatically selected video segments in the summary.","Title: Mobile multimedia presentation in self-forming mobile device groups: ad-hoc networks in practice\nYear: 2012\n\nAbstract: This demo exhibits a new application of mobile ad-hoc networks, where, a group of mobile devices are connected to allow synchronized presentation of multimedia content. The demo is in the form of an interactive tour. Participants have a mobile device and the tour is led by a guide, who takes the group on an informative tour of a locale. The tour is augmented with the presentation of multimedia content on the devices, highlighting points of interest. Content presentation is controlled by the guide and is synchronized using the ad-hoc network. This is an edutainment application but the underlying technology could be applied elsewhere including educational settings and in entertainment.","Title: A comparative evaluation of interactive segmentation algorithms\nYear: 2010\n\nAbstract: In this paper we present a comparative evaluation of four popular interactive segmentation algorithms. The evaluation was carried out as a series of user-experiments, in which participants were tasked with extracting 100 objects from a common dataset: 25 with each algorithm, constrained within a time limit of 2min for each object. To facilitate the experiments, a ''scribble-driven'' segmentation tool was developed to enable interactive image segmentation by simply marking areas of foreground and background with the mouse. As the participants refined and improved their respective segmentations, the corresponding updated segmentation mask was stored along with the elapsed time. We then collected and evaluated each recorded mask against a manually segmented ground truth, thus allowing us to gauge segmentation accuracy over time. Two benchmarks were used for the evaluation: the well-known Jaccard index for measuring object accuracy, and a new fuzzy metric, proposed in this paper, designed for measuring boundary accuracy. Analysis of the experimental results demonstrates the effectiveness of the suggested measures and provides valuable insights into the performance and characteristics of the evaluated algorithms.","Title: Rushes video summarization using a collaborative approach\nYear: 2008\n\nAbstract: This paper describes the video summarization system developed by the partners of the K-Space European Network of Excellence for the TRECVID 2008 BBC rushes summarization evaluation. We propose an original method based on individual content segmentation and selection tools in a collaborative system. Our system is organized in several steps. First, we segment the video, secondly we identify relevant and redundant segments, and finally, we select a subset of segments to concatenate and build the final summary with video acceleration incorporated. We analyze the performance of our system through the TRECVID evaluation.","Title: Identification of sleep apnea events using discrete wavelet transform of respiration, ECG and accelerometer signals.\nYear: 2013\n\nAbstract: Sleep apnea is a common sleep disorder in which patient sleep patterns are disrupted due to recurrent pauses in breathing or by instances of abnormally low breathing. Current gold standard tests for the detection of apnea events are costly and have the addition of long waiting times. This paper investigates the use of cheap and easy to use sensors for the identification of sleep apnea events. Combinations of respiration, electrocardiography (ECG) and acceleration signals were analysed. Results show that using features, formed using the discrete wavelet transform (DWT), from the ECG and acceleration signals provided the highest classification accuracy, with an F1 score of 0.914. However, the novel employment of just the accelerometer signal during classification provided a comparable F1 score of 0.879. By employing one or a combination of the analysed sensors a preliminary test for sleep apnea, prior to the requirement for gold standard testing, can be performed.","Title: Tennissense: a platform for extracting semantic information from multi-camera tennis data\nYear: 2009\n\nAbstract: In this paper, we introduce TennisSense, a technology platform for the digital capture, analysis and retrieval of tennis training and matches. Our algorithms for extracting useful metadata from the overhead court camera are described and evaluated. We track the tennis ball using motion images for ball candidate detection and then link ball candidates into locally linear tracks. From these tracks we can infer when serves and rallies take place. Using background subtraction and hysteresis-type blob tracking, we track the tennis players positions. The performance of both modules is evaluated using ground-truthed data. The extracted metadata provides valuable information for indexing and efficient browsing of hours of multi-camera tennis footage and we briefly illustrative how this data is used by our tennis-coach playback interface.","Title: Interactive surveillance event detection at TRECVid2012\nYear: 2013\n\nAbstract: This demonstration shows the integration of video analysis and search tools to facilitate the interactive retrieval of video segments depicting specific activities from surveillance footage. The implementation was developed by members of the SAVASA project for participation in the interactive surveillance event detection (SED) task of TRECVid 2012. This year, for the first time, the purpose of the interactive SED task was to evaluate systems' ability to support users in identifying video segments that depict a specific activity (event) in a large collection of surveillance video footage. Project partners worked together to analyse video and provide a query interface enabling users to search and identify matching video segments. The collaborative integration of components from multiple partners and the participation of end user partners in evaluating the system are the novel aspects of this work.","Title: Dynamic Voxel Carving In Tennis Based On Player Localisation Using A Low Cost Camera Network\nYear: 2011\n\nAbstract: In this paper, we address the problem of reconstructing 3D volumetric models, illustrating human sporting performance for use in coaching scenarios. We advocate the use of low cost camera networks for acquiring such data, allowing the approach to be feasibly adopted by both amateur and elite level sports athletes. A dynamic voxel carving approach is described, coupled with over-head player tracking and autonomous background subtraction, to automatically produce a 3D reconstruction technique that intelligently uses memory resources. We demonstrate the efficacy of our approach in the context of tennis as a challenging application scenario.","Title: Social recommendation and visual analysis on the TV\nYear: 2010\n\nAbstract: In this paper, we present prototype interactive TV software that incorporates visual content analysis tools and social networking in the home TV. We present the challenges of working with the living room TV environment and outline how we have utilized visual processing and search technologies to address these challenges and create a novel prototype interactive TV system.","Title: An information retrieval approach to identifying infrequent events in surveillance video\nYear: 2013\n\nAbstract: This paper presents work on integrating multiple computer vision-based approaches to surveillance video analysis to support user retrieval of video segments showing human activities. Applied computer vision using real-world surveillance video data is an extremely challenging research problem, independently of any information retrieval (IR) issues. Here we describe the issues faced in developing both generic and specific analysis tools and how they were integrated for use in the new TRECVid interactive surveillance event detection task. We present an interaction paradigm and discuss the outcomes from face-to-face end user trials and the resulting feedback on the system from both professionals, who manage surveillance video, and computer vision or machine learning experts. We propose an information retrieval approach to finding events in surveillance video rather than solely relying on traditional annotation using specifically trained classifiers.","Title: Implementation and Analysis of Several Keyframe-Based Browsing Interfaces to Digital Video\nYear: 2000\n\nAbstract: In this paper we present a variety of browsing interfaces for digital video information. The six interfaces are implemented on top of Físchlár, an operational recording, indexing, browsing and playback system for broadcast TV programmes. In developing the six browsing interfaces, we have been informed by the various dimensions which can be used to distinguish one interface from another. For this we include layeredness (the number of \"layers\" of abstraction which can be used in browsing a programme), the provision or omission of temporal information (varying from full timestamp information to nothing at all on time) and visualisation of spatial vs. temporal aspects of the video. After introducing and defining these dimensions we then locate some common browsing interfaces from the literature in this 3-dimensional \"space\" and then we locate our own six interfaces in this same space. We then present an outline of the interfaces and include some user feedback.","Title: Average Precision: Good Guide or False Friend to Multimedia Search Effectiveness?\nYear: 2014\n\nAbstract: Approaches to multimedia search often evolve from existing approaches with strong average precision. However, work on search evaluation shows that average precision does not always capture effectiveness in terms of satisfying user needs because it ignores the diversity of search results. This paper investigates whether search approaches with diverse results have been neglected within the multimedia retrieval research agenda due the fact that they are overshadowed by search approaches with strong average precision. To this end, we compare 361 search approaches applied on the TrecVid benchmarks between 2005 and 2007. We motivate two criteria based on measure correlation and statistical equivalence to estimate whether search approaches with diverse results have been neglected. We show that hypothesized effect indeed occurs in the above examined collections. As a consequence, the research community would benefit from reconsidering existing approaches in the light of diversity.","Title: Intelligent Middleware for Adaptive Sensing of Tennis Coaching Sessions\nYear: 2009\n\nAbstract: In professional tennis training matches, the coachneeds to be able to view play from the most appropriate anglein order to monitor players activities. In this paper, we presenta system which can adapt the operation of a series of camerasin order to maintain optimal system performance based on aset of wireless sensors. This setup is used as a testbed for anagent based intelligent middleware that can correlate data frommany different wired and wireless sensors and provide effectivein-situ decision making. The proposed solution is flexible enoughto allow the addition of new sensors and actuators. Within thissetup we also provide details of a case study for the embeddedcontrol of cameras through the use of Ubisense data.","Title: Evaluating a dancer's performance using kinect-based skeleton tracking\nYear: 2011\n\nAbstract: In this work, we describe a novel system that automatically evaluates dance performances against a gold-standard performance and provides visual feedback to the performer in a 3D virtual environment. The system acquires the motion of a performer via Kinect-based human skeleton tracking, making the approach viable for a large range of users, including home enthusiasts. Unlike traditional gaming scenarios, when the motion of a user must by kept in synch with a pre-recorded avatar that is displayed on screen, the technique described in this paper targets online interactive scenarios where dance choreographies can be set, altered, practiced and refined by users. In this work, we have addressed some areas of this application scenario. In particular, a set of appropriate signal processing and soft computing methodologies is proposed for temporally aligning dance movements from two different users and quantitatively evaluating one performance against another.","Title: Dublin City University at the TRECVid 2008 BBC rushes summarisation task\nYear: 2008\n\nAbstract: We describe the video summarisation systems submitted by Dublin City University to the TRECVid 2008 BBC Rushes Summarisation task. We introduce a new approach to redundant video summarisation based on principal component analysis and linear discriminant analysis. The resulting low dimensional representation of each shot offers a simple way to compare and select representative shots of the original video. The final summary is constructed as a dynamic storyboard. Both types of summaries were evaluated and the results are discussed.","Title: Designing a touch-screen sensecam browser to support an aging population\nYear: 2010\n\nAbstract: In this paper, we describe the HCI challenges associated with the novel domain of lifelogging for older users. The SenseCam is a passively capturing wearable camera, worn via a lanyard around the neck and used to create a personal lifelog or visual recording of the wearer's life, which generates information that may be very helpful as a human memory aid. Indeed, given that memory defects are more marked in the elderly, we believe that lifelogging browsing techniques which are considerate of the elderly are imperative. Thus, the challenge tackled in this work was to design and integrate the lifelogging activity supported by new technologies in such a way that can easily be learned and used by older people, enabling them to enhance and enrich their lives with the new technologies. This work provides design practitioners of future lifelogging interfaces early sight of the lessons we have learned in making lifelogging technologies accessible to elderly non-computing literate participants.","Title: Low Computational Complexity Variable Block Size (VBS) Partitioning for Motion Estimation Using the Walsh Hadamard Transform (WHT)\nYear: 2009\n\nAbstract: Variable Block Size (VBS) based motion estimation has been adapted in state of the art video coding, such asH.264/AVC, VC-1. However, a low complexity H.264/AVCencoder cannot take advantage of VBS due to its power consumption requirements. In this paper, we present a VBS partition algorithm based on a binary motion edge map without either initial motion estimation or Rate-Distortion (R-D)optimization for selecting modes. The proposed algorithm uses the Walsh Hadamard Transform (WHT) to create a binary edge map, which provides a computational complexity cost effectiveness compared to other light segmentation methods typically used to detect the required region.","Title: Freegaming: Mobile, collaborative, adaptive and augmented exergaming\nYear: 2012\n\nAbstract: Addressing the obesity epidemic that plagues many societies remains an outstanding public health issue. One innovative approach to addressing this problem is Exergaming. A combination of \"Exercise\" and \"Gaming\", the objective is to motivate people participate in exercise regimes, usually in their home environment. In this paper a more holistic interpretation of this exercise paradigm is proposed. Freegaming augments Exergaming in a number of key dimensions but especially through the promotion of games in outdoor mobile contexts and within a social environment. The design and implementation of a platform for Freegaming is described and illustrated through the description of a sample game.","Title: MediAssist: using content-based analysis and context to manage personal photo collections\nYear: 2006\n\nAbstract: We present work which organises personal digital photo collections based on contextual information, such as time and location, combined with content-based analysis such as face detection and other feature detectors. The MediAssist demonstration system illustrates the results of our research into digital photo management, showing how a combination of automatically extracted context and content-based information, together with user annotation, facilitates efficient searching of personal photo collections.","Title: Shrec'08 Entry: Multi-View 3d Retrieval Using Multi-Scale Contour Representation\nYear: 2008\n\nAbstract: We describe in this paper a method for 3D shape indexing and retrieval that we apply on three data collections of the SHREC - SHape Retrieval Contest 2008: Stability on watertight, CAD and Generic 3D models. The method is based on a set of 2D multi-views after a pose and scale normalization of the models using Continuous PCA and the enclosing sphere. In all views we extract the models silhouettes and compare them pairwise. To compute the similitude measure we consider the external contour of the silhouettes, we extract their convexities and concavities at different scale levels and we build a multiscale representation. The pairs of contours are then compared by elastic matching achieved by using dynamic programming.","Title: I like to log: a questionnaire study towards accessible lifelogging for older users\nYear: 2010\n\nAbstract: Lifelogging is the capture and storage of everyday experiences and the act of reviewing lifelog data can significantly support episodic memory, which is particularly vulnerable to the effects of ageing. To design an accessible lifelogging application for older users we firstly need to explore what lifelogging features the application should include. We carried out a questionnaire study to investigate what lifelogging items people from different age groups are currently collecting. Also of interest to us was what items the participants would like to collect and the differences in lifelogging choices between age groups. The results from this questionnaire will contribute to the design of a lifelogging application which focuses on older users' preferences, motivations and abilities.","Title: SenseCam Image Localisation Using Hierarchical SURF Trees\nYear: 2009\n\nAbstract: The SenseCam is a wearable camera that automatically takes photos of the wearer's activities, generating thousands of images per day. Automatically organising these images for efficient search and retrieval is a challenging task, but can be simplified by providing semantic information with each photo, such as the wearer's location during capture time. We propose a method for automatically determining the wearer's location using an annotated image database, described using SURF interest point descriptors. We show that SURF out-performs SIFT in matching SenseCam images and that matching can be done efficiently using hierarchical trees of SURF descriptors. Additionally, by re-ranking the top images using bi-directional SURF matches, location matching performance is improved further.","Title: Real-time head nod and shake detection for continuous human affect recognition\nYear: 2013\n\nAbstract: Human affect recognition is the field of study associated with using automatic techniques to identify human emotion or human affective state. A person's affective states is often communicated non-verbally through body language. A large part of human body language communication is the use of head gestures. Almost all cultures use subtle head movements to convey meaning. Two of the most common and distinct head gestures are the head nod and the head shake gestures. In this paper we present a robust system to automatically detect head nod and shakes. We employ the Microsoft Kinect and utilise discrete Hidden Markov Models (HMMs) as the backbone to a machine learning based classifier within the system. The system achieves 86% accuracy on test datasets and results are provided.","Title: Word matching using single closed contours for indexing handwritten historical documents\nYear: 2007\n\nAbstract: Effective indexing is crucial for providing convenient access to scanned versions of large collections of historically valuable handwritten manuscripts. Since traditional handwriting recognizers based on optical character recognition (OCR) do not perform well on historical documents, recently a holistic word recognition approach has gained in popularity as an attractive and more straightforward solution (Lavrenko et al. in proc. document Image Analysis for Libraries (DIAL'04), pp. 278---287, 2004). Such techniques attempt to recognize words based on scalar and profile-based features extracted from whole word images. In this paper, we propose a new approach to holistic word recognition for historical handwritten manuscripts based on matching word contours instead of whole images or word profiles. The new method consists of robust extraction of closed word contours and the application of an elastic contour matching technique proposed originally for general shapes (Adamek and O'Connor in IEEE Trans Circuits Syst Video Technol 5:2004). We demonstrate that multiscale contour-based descriptors can effectively capture intrinsic word features avoiding any segmentation of words into smaller subunits. Our experiments show a recognition accuracy of 83%, which considerably exceeds the performance of other systems reported in the literature.","Title: Toward Automatic Activity Classification and Movement Assessment During a Sports Training Session\nYear: 2015\n\nAbstract: Motion analysis technologies have been widely used to monitor the potential for injury and enhance athlete performance. However, most of these technologies are expensive, can only be used in laboratory environments, and examine only a few trials of each movement action. In this paper, we present a novel ambulatory motion analysis framework using wearable inertial sensors to accurately assess all of an athlete's activities in real training environment. We first present a system that automatically classifies a large range of training activities using the discrete wavelet transform (DWT) in conjunction with a random forest classifier. The classifier is capable of successfully classifying various activities with up to 98% accuracy. Second, a computationally efficient gradient descent algorithm is used to estimate the relative orientations of the wearable inertial sensors mounted on the shank, thigh, and pelvis of a subject, from which the flexion-extension knee and hip angles are calculated. These angles, along with sacrum impact accelerations, are automatically extracted for each stride during jogging. Finally, normative data are generated and used to determine if a subject's movement technique differed to the normative data in order to identify potential injury-related factors. For the joint angle data, this is achieved using a curve-shift registration technique. It is envisaged that the proposed framework could be utilized for accurate and automatic sports activity classification and reliable movement technique evaluation in various unconstrained environments for both injury management and performance enhancement.","Title: Object Segmentation in Images using EEG Signals\nYear: 2014\n\nAbstract: This paper explores the potential of brain-computer interfaces in segmenting objects from images. Our approach is centered around designing an effective method for displaying the image parts to the users such that they generate measurable brain reactions. When an image region, specifically a block of pixels, is displayed we estimate the probability of the block containing the object of interest using a score based on EEG activity. After several such blocks are displayed, the resulting probability map is binarized and combined with the GrabCut algorithm to segment the image into object and background regions. This study shows that BCI and simple EEG analysis are useful in locating object boundaries in images.","Title: Life-Long Collections: Motivations and the Implications for Lifelogging with Mobile Devices\nYear: 2014\n\nAbstract: In this paper the authors investigate the motivations for life-long collections and how these motivations can inform the design of future lifelog systems. Lifelogging is the practice of automatically capturing data from daily life experiences with mobile devices, such as smartphones and wearable cameras. Lifelog archives can benefit both older and younger people; therefore lifelog systems should be designed for people of all ages. The authors believe that people would be more likely to adopt lifelog practices that support their current motivations for collecting items. To identify these motivations, ten older and ten younger participants were interviewed. It was found that motivations for and against life-long collections evolve as people age and enter different stages, and that family is at the core of life-long collections. These findings will be used to guide the design of an intergenerational lifelog browser.","Title: Automatic Activity Classification and Movement Assessment During a Sports Training Session Using Wearable Inertial Sensors\nYear: 2014\n\nAbstract: Motion analysis technologies have been widely used to monitor the potential for injury and enhance athlete performance. However, most of these technologies are expensive, can only be used in laboratory environments and examine only a few trials of each movement action. In this paper, we present a novel ambulatory motion analysis framework using wearable inertial sensors to accurately assess all of an athlete's activities in an outdoor training environment. We firstly present a system that automatically classifies a large range of training activities using the Discrete Wavelet Transform (DWT) in conjunction with a Random forest classifier. The classifier is capable of successfully classifying various activities with up to 98% accuracy. Secondly, a computationally efficient gradient descent algorithm is used to estimate the relative orientations of the wearable inertial sensors mounted on the thigh and shank of a subject, from which the flexion-extension knee angle is calculated. Finally, a curve shift registration technique is applied to both generate normative data and determine if a subject's movement technique differed to the normative data in order to identify potential injury related factors. It is envisaged that the proposed framework could be utilized for accurate and automatic sports activity classification and reliable movement technique evaluation in various unconstrained environments.","Title: Low-cost accurate skeleton tracking based on fusion of kinect and wearable inertial sensors\nYear: 2014\n\nAbstract: In this paper, we present a novel multi-sensor fusion method to build a human skeleton. We propose to fuse the joint position information obtained from the popular Kinect sensor with more precise estimation of body segment orientations provided by a small number of wearable inertial sensors. The use of inertial sensors can help to address many of the well known limitations of the Kinect sensor. The precise calculation of joint angles potentially allows the quantification of movement errors in technique training, thus facilitating the use of the low-cost Kinect sensor for accurate biomechanical purposes e.g. the improved human skeleton could be used in visual feedback-guided motor learning, for example. We compare our system to the gold standard Vicon optical motion capture system, proving that the fused skeleton achieves a very high level of accuracy.","Title: Interactive games for preservation and promotion of sporting movements\nYear: 2014\n\nAbstract: In this paper we describe two interactive applications for capturing the motion signatures associated with key skills of traditional sports and games. We first present the case for sport as an important example of intangible cultural heritage. We then explain that sport requires special consideration in terms of digitization for preservation as the key aspects to be digitized are the characteristic movement signatures of such sports. We explain that, given the nature of traditional sporting agencies, this requires low-cost motion capture technology. Furthermore we argue that in order to ensure ongoing preservation, this should be provided via fun interactive gaming scenarios that promote uptake of the sports, particularly among children. We then present two such games that we have developed and illustrate their performance.","Title: Capturing The Sporting Heroes Of Our Past By Extracting 3d Movements From Legacy Video Content\nYear: 2014\n\nAbstract: Ports are a key part of cultural identity, and it is necessary to preserve them as important intangible Cultural Heritage, especially the human motion techniques specific to individual sports. In this paper we present a method for extracting 3D athlete motion from video broadcast sources, providing an important tool for preserving the heritage represented by these movements. Broadcast videos include camera motion, multiple player interaction, occlusions and noise, presenting significant challenges to solve the reconstruction. The approach requires initial definition of some key-frames and setting of 2D key-points in those frames manually. Thereafter an automatic process estimates the poses and positions of the players in the key-frames, and in the frames between key-frames, taking into account collisions with the environment and human kinematic constraints. Initial results are extremely promising and this data could be used to analyze the sport's evolution over time, or even to generate animations for interactive applications.","Title: SEAMLOC: Seamless Indoor Localization Based on Reduced Number of Calibration Points\nYear: 2014\n\nAbstract: Indoor localization based on ubiquitous WLAN has exhibited the capability of being a cheap and relatively precise technology and has been verified by many successful examples. Its performance is subject to change due to multipath propagation and changes in the environment (people, building layouts, antenna characteristics, etc.) which cannot be eliminated easily. An indoor localization and tracking algorithm is described which is based on the creation of a database of WLAN signal strengths at pre-chosen calibration points (CPs). The need for fewer CPs than in standard methods is due to use of a novel interpolation algorithm, based on the specification of robust, range and angle-dependent likelihood functions that describe the probability of a user being in the vicinity of each CP. The actual location of the user is estimated by solving a system of two non-linear equations with two unknowns derived for a pair of CPs. Different pairs of CPs can be chosen to make several estimates which then can be combined to increase the accuracy of the estimate. A variety of results are presented using challenging data collected in a typical office environment which demonstrate the accuracy that can be achieved with a reduced number of CPs.)) The method is compared to several competing localization methods and is shown to give superior results.","Title: An Improved Spatiogram Similarity Measure for Robust Object Localisation\nYear: 2007\n\nAbstract: Spatiograms were introduced as a generalisation of the com- monly used histogram, providing the flexibility of adding spa- tial context information to the feature distribution information of a histogram. The originally proposed spatiogram com- parison measure has significant disadvantages that we detail here. We propose an improved measure based on deriving the Bhattacharyya coefficient for an infinite number of spatial- feature bins. Its advantages over the previous measure and over histogram-based matching are demonstrated in object tracking scenarios.","Title: Optimising resource allocation for background modeling using algorithm switching\nYear: 2008\n\nAbstract: Background maintenance is a complex problem due to varying scene conditions. Typically, a single algorithm cannot handle the complex scene changes that occur in visual surveillance applications. Also complex background modelling techniques, for example mixture of Gaussians have a high computational and communication demand compared to simple techniques such as a uni-model background model or simple frame-differencing with an adaptive threshold. In this paper we present an algorithm switching approach that can handle multi-model background scenes. Starting with a less computational and less data intensive uni-model background subtraction algorithm the system switches to a complex multi-model background subtraction there by saving valuable software and hardware resources both in terms of power and computation time. Our results show this algorithm switching approach can be used to effectively handle various scene conditions encountered in real time surveillance systems with optimal use of system resources.","Title: Visualisation of tennis swings for coaching\nYear: 2012\n\nAbstract: As a proficient tennis swing is a key element of success in tennis, many amateur tennis players spend a considerable amount of time and effort perfecting their tennis stroke mechanics, hoping to create more accuracy, consistency and power in their swing. In order to achieve these aims effectively a number of independent aspects of technique need to be addressed, including forming a correct racket grip, shot timing, body orientation and precise follow-through. Outside of a one-to-one coaching scenario, where constant professional feedback on technique can be provided, keeping all aspects of technique in mind can overwhelm amateur players. In this work, we have developed a set of visualisation tools to augment the development of amateur tennis players between dedicated one-to-one coaching sessions in the area of technique, timing and body posture. Our approach temporally aligns an amateur player's swing dynamics with that of an elite athlete, allowing direct technique comparison using augmented reality techniques.","Title: Investigating older and younger peoples' motivations for lifelogging with wearable cameras\nYear: 2013\n\nAbstract: People have a natural tendency to collect things about themselves, their experiences and their shared experiences with people important to them, especially family. Similar to traditional objects such as photographs, lifelogs have been shown to support reminiscence. A lifelog is a digital archive of a person's experiences and activities and lifelog devices such as wearable cameras can automatically and continuously record events throughout a whole day. We were interested in investigating what would motivate people to lifelog. Due to the importance of shared family reminiscence between family members we focused our study on comparing shared or personal motivations with ten older and ten younger family members. We found from our results that both older and younger adults were more likely to lifelog for the purposes of information sharing and that reviewing lifelog images supported family reminiscence, reflection and story-telling. Based on these findings, recommendations are made for the design of a novel intergenerational family lifelog system.","Title: Identifying an efficient and robust sub-shot segmentation method for home movie summarisation\nYear: 2010\n\nAbstract: With the increasing volumes of home video footage and the need for effectively managing such archives, home movie summarisation has become an important and key research topic in the recent past. Despite growing interest from the research community, automatic summarisation remains a challenging research problem due to unrestricted capture and lack of storyline present in the home video content. In this paper, we address a sub-problem of the broad summarisation problem, namely sub-shot segmentation, as an important content analysis step in home movie summarisation. More specifically, we conduct an experimental study to identify an efficient and robust sub-shot segmentation method through a performance comparison of a number of optical flow field computation methods. Formulating the task of sub-shot segmentation as a process of decomposing a raw video into different video segments in line with the change in dominant camera motion, we are interested in detecting the most useful camera motions we have observed in real collections, namely pan, tilt and zoom. To this end, a number of feature-based optical flow field computation methods, including two well-known local feature descriptors called SIFT and SURF, and the Pyramidal Lucas-Kanade (PLK) local feature tracker, are investigated as potentially useful approaches for facilitating efficient and robust sub-shot segmentation in this paper. We then compare the performance of those algorithms with 5 different block matching motion estimation algorithms. Simulation results show that the PLK algorithm outperforms the SIFT and SURF algorithms in terms of both accuracy and efficiency. Furthermore, despite its slightly lower accuracy compared to that of the most optimal block matching algorithms (BMA), we conclude that a local feature tracker like the PLK algorithm is the preferred choice for sub-shot detection in real-life home movie archives due to the trade-off it provides between accuracy and efficiency.","Title: Action recognition based on sparse motion trajectories\nYear: 2013\n\nAbstract: We present a method that extracts effective features in videos for human action recognition. The proposed method analyses the 3D volumes along the sparse motion trajectories of a set of interest points from the video scene. To represent human actions, we generate a Bag-of-Features (BoF) model based on extracted features, and finally a support vector machine is used to classify human activities. Evaluation shows that the proposed features are discriminative and computationally efficient. Our method achieves state-of-the-art performance with the standard human action recognition benchmarks, namely KTH and Weizmann datasets.","Title: Game, shot and match: Event-based indexing of tennis\nYear: 2011\n\nAbstract: Identifying events in sports video offers great potential for advancing visual sports coaching applications. In this paper, we present our results for detecting key events in a tennis match. Our overall goal is to automatically index a complete tennis match into all the main tennis events, so that a match can be recorded using affordable visual sensing equipment and then be automatically indexed into key events for retrieval and editing. The tennis events detected in this paper are a tennis game, a change of end and a tennis serve - all of which share temporal commonalities. There are of course other events in tennis which we aim to index in our overall indexing system, but this paper focuses solely on the aforementioned tennis events. This paper proposes a novel approach to detect key events in an instrumented tennis environment by analysing a players location and the visual features of a player.","Title: Visual analysis for drum sequence transcription\nYear: 2007\n\nAbstract: A system is presented for analysing drum performance video se- quences. A novel ellipse detection algorithm is introduced that au- tomatically locates drum tops. This algorithm fits ellipses to edge clusters, and ranks them according to various fitness criteria. A background/foreground segmentation method is then used to extract the silhouette of the drummer and drum sticks. Coupled with a mo- tion intensity feature, this allows for the detection of 'hits' in each of the extracted regions. In order to obtain a transcription of the performance, each of these regions is automatically labeled with the corresponding instrument class. A partial audio transcription and color cues are used to measure the compatibility between a re- gion and its label, the Kuhn-Munkres algorithm is then employed to find the optimal labeling. Experimental results demonstrate the ability of visual analysis to enhance the performance of an audio drum transcription system.","Title: Team behavior analysis in sports using the Poisson equation\nYear: 2012\n\nAbstract: We propose a novel physics-based model for analysing team players' positions and movements on a sports playing field. The goal is to detect for each frame the region with the highest population of a given team's players and the region towards which the team is moving as they press for territorial advancement, termed the region of intent. Given the positions of team players from a plan view of the playing field at any given time, we solve a particular Poisson equation to generate a smooth distribution. The proposed distribution provides the likelihood of a point to be occupied by players so that more highly populated regions can be detected by appropriate thresholding. Computing the proposed distribution for each frame provides a sequence of distributions, which we process to detect the region of intent at any time during the game. Our model is evaluated on a field hockey dataset, and results show that the proposed approach can provide effective features that could be used to generate team statistics useful for performance evaluation or broadcasting purposes.","Title: Low-Energy Symmetric Key Distribution in Wireless Sensor Networks\nYear: 2011\n\nAbstract: In this work, a scheme for key distribution and network access in a Wireless Sensor Network (WSN) that utilizes Identity-Based Cryptography (IBC) is presented. The scheme is analyzed on the ARM920T processor and measurements were taken for the runtime and energy of its components. It was found that the Tate pairing component of the scheme consumes significant amounts of energy, and so should be ported to hardware. An accelerator was implemented in 65 nm Complementary Metal Oxide Silicon (CMOS) technology and area, timing, and energy figures have been obtained for the design. Results indicate that a hardware implementation of IBC would meet the strict energy constraint required of a wireless sensor network node.","Title: Remote real-time monitoring of subsurface landfill gas migration.\nYear: 2011\n\nAbstract: The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months.","Title: A neural network approach to smarter sensor networks for water quality monitoring.\nYear: 2012\n\nAbstract: Environmental monitoring is evolving towards large-scale and low-cost sensor networks operating reliability and autonomously over extended periods of time. Sophisticated analytical instrumentation such as chemo-bio sensors present inherent limitations because of the number of samples that they can take. In order to maximize their deployment lifetime, we propose the coordination of multiple heterogeneous information sources. We use rainfall radar images and information from a water depth sensor as input to a neural network (NN) to dictate the sampling frequency of a phosphate analyzer at the River Lee in Cork, Ireland. This approach shows varied performance for different times of the year but overall produces output that is very satisfactory for the application context in question. Our study demonstrates that even with limited training data, a system for controlling the sampling rate of the nutrient sensor can be set up and can improve the efficiency of the more sophisticated nodes of the sensor network.","Title: Classification of sporting activities using smartphone accelerometers.\nYear: 2013\n\nAbstract: In this paper we present a framework that allows for the automatic identification of sporting activities using commonly available smartphones. We extract discriminative informational features from smartphone accelerometers using the Discrete Wavelet Transform (DWT). Despite the poor quality of their accelerometers, smartphones were used as capture devices due to their prevalence in today's society. Successful classification on this basis potentially makes the technology accessible to both elite and non-elite athletes. Extracted features are used to train different categories of classifiers. No one classifier family has a reportable direct advantage in activity classification problems to date; thus we examine classifiers from each of the most widely used classifier families. We investigate three classification approaches; a commonly used SVM-based approach, an optimized classification model and a fusion of classifiers. We also investigate the effect of changing several of the DWT input parameters, including mother wavelets, window lengths and DWT decomposition levels. During the course of this work we created a challenging sports activity analysis dataset, comprised of soccer and field-hockey activities. The average maximum F-measure accuracy of 87% was achieved using a fusion of classifiers, which was 6% better than a single classifier model and 23% better than a standard SVM approach.","Title: The Convergence of Virtual Reality and Social Networks: Threats to Privacy and Autonomy.\nYear: 2016\n\nAbstract: The rapid evolution of information, communication and entertainment technologies will transform the lives of citizens and ultimately transform society. This paper focuses on ethical issues associated with the likely convergence of virtual realities (VR) and social networks (SNs), hereafter VRSNs. We examine a scenario in which a significant segment of the world's population has a presence in a VRSN. Given the pace of technological development and the popularity of these new forms of social interaction, this scenario is plausible. However, it brings with it ethical problems. Two central ethical issues are addressed: those of privacy and those of autonomy. VRSNs pose threats to both privacy and autonomy. The threats to privacy can be broadly categorized as threats to informational privacy, threats to physical privacy, and threats to associational privacy. Each of these threats is further subdivided. The threats to autonomy can be broadly categorized as threats to freedom, to knowledge and to authenticity. Again, these three threats are divided into subcategories. Having categorized the main threats posed by VRSNs, a number of recommendations are provided so that policy-makers, developers, and users can make the best possible use of VRSNs.","Title: A multi-modal dance corpus for research into interaction between humans in virtual environments\nYear: 2013\n\nAbstract: We present a new, freely available, multimodal corpus for research into, amongst other areas, real-time realistic interaction between humans in online virtual environments. The specific corpus scenario focuses on an online dance class application scenario where students, with avatars driven by whatever 3D capture technology is locally available to them, can learn choreographies with teacher guidance in an online virtual dance studio. As the dance corpus is focused on this scenario, it consists of student/teacher dance choreographies concurrently captured at two different sites using a variety of media modalities, including synchronised audio rigs, multiple cameras, wearable inertial measurement devices and depth sensors. In the corpus, each of the several dancers performs a number of fixed choreographies, which are graded according to a number of specific evaluation criteria. In addition, ground-truth dance choreography annotations are provided. Furthermore, for unsynchronised sensor modalities, the corpus also includes distinctive events for data stream synchronisation. The total duration of the recorded content is 1 h and 40 min for each single sensor, amounting to 55 h of recordings across all sensors. Although the dance corpus is tailored specifically for an online dance class application scenario, the data is free to download and use for any research and development purposes.","Title: Real-time event classification in field sport videos\nYear: 2015\n\nAbstract: The paper presents a novel approach to real-time event detection in sports broadcasts. We present how the same underlying audio-visual feature extraction algorithm based on new global image descriptors is robust across a range of different sports alleviating the need to tailor it to a particular sport. In addition, we propose and evaluate three different classifiers in order to detect events using these features: a feed-forward neural network, an Elman neural network and a decision tree. Each is investigated and evaluated in terms of their usefulness for real-time event classification. We also propose a ground truth dataset together with an annotation technique for performance evaluation of each classifier useful to others interested in this problem. HighlightsArticle presents novel system for real-time video indexing for field sports videos based on the new video description technique.Up to date there is no system that covers so many different sports genres, features so high accuracy and is capable of working in real-time.Several classifiers were compared in the results section which gives additional knowledge about the system features.","Title: Improving object segmentation by using EEG signals and rapid serial visual presentation\nYear: 2015\n\nAbstract: This paper extends our previous work on the potential of EEG-based brain computer interfaces to segment salient objects in images. The proposed system analyzes the Event Related Potentials (ERP) generated by the rapid serial visual presentation of windows on the image. The detection of the P300 signal allows estimating a saliency map of the image, which is used to seed a semi-supervised object segmentation algorithm. Thanks to the new contributions presented in this work, the average Jaccard index was improved from 0.47 to 0.66 when processed in our publicly available dataset of images, object masks and captured EEG signals. This work also studies alternative architectures to the original one, the impact of object occupation in each image window, and a more robust evaluation based on statistical analysis and a weighted F-score.","Title: Automatically detecting asymmetric running using time and frequency domain features\nYear: 2015\n\nAbstract: Human motion analysis technologies have been widely employed to identify injury determining factors and provide objective and quantitative feedback to athletes to help prevent injury. However, most of these technologies are: expensive, restricted to laboratory environments, and can require significant post processing. This reduces their ecological validity, adoption and usefulness. In this paper, we present a novel wearable inertial sensor framework to accurately distinguish between symmetrical and asymmetrical running patterns in an unconstrained environment. The framework can automatically classify symmetry/asymmetry using Short Time Fourier Transform (STFT) and other time domain features in conjunction with a customized Random Forest classifier. The accuracy of the designed framework is up to 94% using 3-D accelerometer and 3-D gyroscope data from a sensor node attached on the upper back of a subject. The upper back inertial sensors data were then down-sampled by a factor of 4 to simulate utilizing low-cost inertial sensors whilst also facilitating a decrease of the computational cost to achieve near real-time application. We conclude that the proposed framework can potentially pave the way for employing low-cost sensors, such as those used in smartphones, attached on the upper back to provide injury related and performance feedback in real-time in unconstrained environments.","Title: HeartHealth: New Adventures in Serious Gaming\nYear: 2015\n\nAbstract: We present a novel, low-cost, interactive, exercise-based rehabilitation system. Our research involves the investigation and development of patient-centric, sensor-based rehabilitation games and surrounding technologies. HeartHealth is designed to provide a safe, personalised and fun exercise environment that could be deployed in any exercise based rehabilitation program. HeartHealth utilises a cloud-based patient information management system built on FIWARE Generic Enablers,and motion tracking coupled with our sophisticated motion comparison algorithms. Users can record customised exercises through a doctors interface and then play the rehabilitation game where they must perform a sequence of their exercises in order to complete the game scenario. Their exercises are monitored, recorded and compared by our Motion Evaluation software and real-time feedback is than given based on the users performance.","Title: A Multi-Modal 3D Capturing Platform for Learning and Preservation of Traditional Sports and Games\nYear: 2015\n\nAbstract: We present a demonstration of a multi-modal 3D capturing platform coupled to a motion comparison system. This work is focused on the preservation of Traditional Sports and Games, namely the Gaelic sports from Ireland and Basque sports from France and Spain. Users can learn, compare and compete in the performance of sporting gestures and compare themselves to real athletes. Our online gesture database provides a way to preserve and display a wide range of sporting gestures. The capturing devices utilised are Kinect 2 sensors and wearable inertial sensors, where the number required varies based on the requested scenario. The fusion of these two capture modalities, coupled to our inverse kinematic algorithm, allow us to synthesize a fluid and reliable 3D model of the user gestures over time. Our novel comparison algorithms provide the user with a performance score and a set of comparison curves (i.e. joint angles and angular velocities), providing a precise and valuable feedback for coaches and players.","Title: Combining inertial and visual sensing for human action recognition in tennis\nYear: 2010\n\nAbstract: In this paper, we present a framework for both the automatic extraction of the temporal location of tennis strokes within a match and the subsequent classification of these as being either a serve, forehand or backhand. We employ the use of low-cost visual sensing and low-cost inertial sensing to achieve these aims, whereby a single modality can be used or a fusion of both classification strategies can be adopted if both modalities are available within a given capture scenario. This flexibility allows the framework to be applicable to a variety of user scenarios and hardware infrastructures. Our proposed approach is quantitatively evaluated using data captured from elite tennis players. Results point to the extremely accurate performance of the proposed approach irrespective of input modality configuration","Title: The Real Time Rolling Shutter\nYear: 2015\n\nAbstract: From an early age children are often told either, you are creative you should do art but stay away from science and maths. Or that you are mathematical you should do science but you're not that creative. Compounding this there also exist some traditional barriers of artistic rhetoric that say, \"don't touch, don't think and don't be creative, we've already done that for you, you can just look...\". The Real Time Rolling Shutter is part of a collaborative Art/Science partnership whose core tenets are in complete contrast to this. The Art/Science exhibitions we have created have invited the public to become part of the exhibition by utilising augmented digital mirrors, Kinects, feed-back camera and projector systems and augmented reality perception helmets. The fundamental underlying principles we are trying to adhere to are to foster curiosity, intrigue, wonderment and amazement and we endeavour to draw the audience into the interactive nature of our exhibits and exclaim to everyone that you can be what ever you chose to be, and that everyone can be creative, everyone can be an artist, everyone can be a scientist... all it takes is an inquisitive mind, so come and explore the real-time rolling shutter and be creative.","Title: Background Modelling in Infrared and Visible Spectrum Video for People Tracking\nYear: 2005\n\nAbstract: In this paper, we present our approach to robust background modelling which combines visible and thermal infrared spectrum data. Our work is based on the non-parametric background model describe in 1. We use a pedestrian detection module to prevent erroneous data from becoming part of the background model and this allows us to initialise our bacjground model, even in the presence of foreground objects. Visible and infrared features are use to remove incorrectly detected foreground regions. Allowing our model to quickly recover from ghost regions and rapid lighting changes. An object-basedshadow detector also improves our algorithm's performance.","Title: LoggerMan, a Comprehensive Logging and Visualization Tool to Capture Computer Usage.\nYear: 2016\n\nAbstract: As we become increasingly dependent on our computers and spending a major part of our day interacting with these machines, it is becoming important for lifeloggers and Human-Computer Interaction (HCI) researchers to capture this aspect of our life. In this paper, we present LoggerMan, a comprehensive logging tool to capture many aspects of our computer usage. It also comes with reporting capabilities to give insights to the data owner about his/her computer usage. In this work, we aim to address the current lack of logging software in this domain, which would help us, and other researchers, to build datasets for HCI experiments and also to better understand computer usage patterns. Our tool is published online (http://loggerman.org/) to be used freely by the community.","Title: Exploring EEG for Object Detection and Retrieval.\nYear: 2015\n\nAbstract: This paper explores the potential for using Brain Computer Interfaces (BCI) as a relevance feedback mechanism in content-based image retrieval. Several experiments are performed using a rapid serial visual presentation (RSVP) of images at different rates (5Hz and 10Hz) on 8 users with different degrees of familiarization with BCI and the dataset. We compare the feedback from the BCI and mouse-based interfaces in a subset of TRECVid images, finding that, when users have limited time to annotate the images, both interfaces are comparable in performance. Comparing our best users in a retrieval task, we found that EEG-based relevance feedback can outperform mouse-based feedback.","Title: HeartHealth: A cardiovascular disease home-based rehabilitation system\nYear: 2015\n\nAbstract: The increasing pressure on medical institutions around the world requires health care professionals to be prescribing home- based exercise rehabilitation treatments to empower patients to self-monitor their rehabilitation journey. Home-based exercise rehabilitation has shown to be highly effective in treating conditions such as Cardiovascular Disease (CVD). However, adherence to home-based exercise rehabilitation remains low. Possible causes for this are that patients are not monitored, they cannot be con- fident that they are performing the exercise correctly or accurately and they receive no feedback. This paper proposes HeartHealth, a novel patient-centric gamified exercise rehabilitation platform that can help address the issue of adherence to these programmes. The key functionality is the ability to record the patient movements and compare them against the exercises that have been pre- scribed in order to return feedback to the patient and to the health care professional, as well. In order to synthesize a compact fully operational system able to work in real life scenarios, tools and services from FI-PPP projects, FIWARE 1 and FI-STAR 2, were exploited and a new FI-STAR component, Motion Evaluation Specific Enabler (SE), was designed and developed. The HeartHealth system brings together real-time cloud-based motion evaluation coupled with accurate low-cost motion capture, a personalised ex- ercise rehabilitation programme and an intuitive and fun serious game interface, designed specifically with a Cardiac Rehabilitation population in mind.","Title: Action recognition in video using a spatial-temporal graph-based feature representation\nYear: 2015\n\nAbstract: We propose a video graph based human action recognition framework. Given an input video sequence, we extract spatio-temporal local features and construct a video graph to incorporate appearance and motion constraints to reflect the spatio-temporal dependencies among features. them. In particular, we extend a popular dbscan density-based clustering algorithm to form an intuitive video graph. During training, we estimate a linear SVM classifier using the standard Bag-of-words method. During classification, we apply Graph-Cut optimization to find the most frequent action label in the constructed graph and assign this label to the test video sequence. The proposed approach achieves state-of-the-art performance with standard human action recognition benchmarks, namely KTH and UCF-sports datasets and competitive results for the Hollywood (HOHA) dataset.","Title: Bags of Local Convolutional Features for Scalable Instance Search.\nYear: 2016\n\nAbstract: This work proposes a simple instance retrieval pipeline based on encoding the convolutional features of CNN using the bag of words aggregation scheme (BoW). Assigning each local array of activations in a convolutional layer to a visual word produces an assignment map, a compact representation that relates regions of an image with a visual word. We use the assignment map for fast spatial reranking, obtaining object localizations that are used for query expansion. We demonstrate the suitability of the BoW representation based on local CNN features for instance retrieval, achieving competitive performance on the Oxford and Paris buildings benchmarks. We show that our proposed system for CNN feature aggregation with BoW outperforms state-of-the-art techniques using sum pooling at a subset of the challenging TRECVid INS benchmark.","Title: Introduction to the Issue on Person-Centered Signal Processing for Assistive, Rehabilitative, and Wearable Health Technologies.\nYear: 2016\n\nAbstract: The thirteen papers in this special issue aims to bring awareness to the need and importance of person-centered design in computing and signal processing solutions, and presents advances in person-centered signal processing for assistive, rehabilitative, and wearable health technologies.","Title: Designing a Topological Algorithm for 3D Activity Recognition.\nYear: 2016\n\nAbstract: Voxel carving is a non-invasive and low-cost technique that is used for the reconstruction of a 3D volume from images captured from a set of cameras placed around the object of interest. In this paper we propose a method to topologically analyze a video sequence of 3D reconstructions representing a tennis player performing different forehand and backhand strokes with the aim of providing an approach that could be useful in other sport activities.","Title: Where is my Phone ? Personal Object Retrieval from Egocentric Images.\nYear: 2016\n\nAbstract: This work presents a retrieval pipeline and evaluation scheme for the problem of finding the last appearance of personal objects in a large dataset of images captured from a wearable camera. Each personal object is modelled by a small set of images that define a query for a visual search engine.The retrieved results are reranked considering the temporal timestamps of the images to increase the relevance of the later detections. Finally, a temporal interleaving of the results is introduced for robustness against false detections. The Mean Reciprocal Rank is proposed as a metric to evaluate this problem. This application could help into developing personal assistants capable of helping users when they do not remember where they left their personal belongings.","Title: A Multimodal Gamified Platform for Real-Time User Feedback in Sports Performance.\nYear: 2016\n\nAbstract: In this paper we introduce a novel platform that utilises multi-modal low-cost motion capture technology for the delivery of real-time visual feedback for sports performance. This platform supports the expansion to multi-modal interfaces that utilise haptic and audio feedback, which scales effectively with motor task complexity. We demonstrate an implementation of our platform within the field of sports performance. The platform includes low-cost motion capture through a fusion technique, combining a Microsoft Kinect V2 with two wrist inertial sensors, which make use of the accelerometer and gyroscope sensors, alongside a game-based Graphical User Interface (GUI) for instruction, visual feedback and gamified score tracking.","Title: Vector Quantization Enhancement for Computer Vision Tasks.\nYear: 2016\n\nAbstract: This paper augments the Bag-of-Word scheme in several respects: we incorporate a category label into the clustering process, build classifier-tailored codebooks, and weight codewords according to their probability to occur. A size-adaptive feature clustering algorithm is also proposed as an alternative to k-means. Experiments on the PASCAL VOC 2007 challenge validate the approach for classical hard-assignment as well as VLAD encoding.","Title: TREAT: Terse Rapid Edge-Anchored Tracklets\nYear: 2016\n\nAbstract: Fast computation, efficient memory storage, and performance on par with standard state-of-the-art descriptors make binary descriptors a convenient tool for many computer vision applications. However their development is mostly tailored for static images. To respond to this limitation, we introduce TREAT (Terse Rapid Edge-Anchored Tracklets), a new binary detector and descriptor, based on tracklets. It harnesses moving edge maps to perform efficient feature detection, tracking, and description at low computational cost. Experimental results on 3 different public datasets demonstrate improved performance over other popular binary features. These experiments also provide a basis for benchmarking the performance of binary descriptors in video-based applications.","Title: A flexible ensemble-SVM for computer vision tasks\nYear: 2016\n\nAbstract: This paper presents an ensemble-SVM method that features a data selection mechanism with stochastic and deterministic properties, the use of extreme value theory for classifier calibration, and the introduction of random forest for classifier combination. We applied the proposed algorithm to 2 event recognition datasets and the PASCAL2007 object detection dataset and compared it to single SVM and common computer vision ensemble-SVM methods. Our algorithm outperforms its competitors and shows a considerable boost on datasets with a limited amount of outliers.","Title: Fully Convolutional Crowd Counting On Highly Congested Scenes\nYear: 2017\n\nAbstract: In this paper we advance the state-of-the-art for crowd counting in high density scenes by further exploring the idea of a fully convolutional crowd counting model introduced by (Zhang et al., 2016). Producing an accurate and robust crowd count estimator using computer vision techniques has attracted significant research interest in recent years. Applications for crowd counting systems exist in many diverse areas including city planning, retail, and of course general public safety. Developing a highly generalised counting model that can be deployed in any surveillance scenario with any camera perspective is the key objective for research in this area. Techniques developed in the past have generally performed poorly in highly congested scenes with several thousands of people in frame (Rodriguez et al., 2011). Our approach, influenced by the work of (Zhang et al., 2016), consists of the following contributions: (1) A training set augmentation scheme that minimises redundancy among training samples to improve model generalisation and overall counting performance; (2) a deep, single column, fully convolutional network (FCN) architecture; (3) a multi-scale averaging step during inference. The developed technique can analyse images of any resolution or aspect ratio and achieves state-of-the-art counting performance on the Shanghaitech Part_B and UCF_CC_50 datasets as well as competitive performance on Shanghaitech Part_A.","Title: SalGAN: Visual Saliency Prediction with Generative Adversarial Networks.\nYear: 2017\n\nAbstract: We introduce SalGAN, a deep convolutional neural network for visual saliency prediction trained with adversarial examples. The first stage of the network consists of a generator model whose weights are learned by back-propagation computed from a binary cross entropy (BCE) loss over downsampled versions of the saliency maps. The resulting prediction is processed by a discriminator network trained to solve a binary classification task between the saliency maps generated by the generative stage and the ground truth ones. Our experiments show how adversarial training allows reaching state-of-the-art performance across different metrics when combined with a widely-used loss function like BCE. Our results can be reproduced with the source code and trained models available at https://imatge-upc.github. io/saliency-salgan-2017/.","Title: A Demonstration of the PATHway System for Technology-enabled Exercise-based Cardiac Rehabilitation.\nYear: 2016\n\nAbstract: We described an invited demonstration to MMHealth'16 of a platform for technology-enabled exercise-based Cardiac Rehabilitation (CR). The demo focuses on one technical aspect of a much broader lifestyle intervention program i.e. real-time estimation of a user's adherence to an exercise programme.","Title: A Technology Platform for Enabling Behavioural Change as a \"PATHway\" Towards Better Self-management of CVD.\nYear: 2016\n\nAbstract: We describe a technology platform developed as part of a novel approach to technology-enabled exercise-based Cardiac Rehabilitation (CR), termed PATHway. We explain the overall concept and explain how technology can facilitate remote participation and better adherence to community-based long-term Phase III CR. The demo will showcase the user experience of interacting with the PATHway system, including navigation and manual data entry, whilst also demonstrating real-time sensing and analysis of exercise movements and automatic adaptation of exercise based on physiological response.","Title: Smart Stadium for Smarter Living: Enriching the Fan Experience\nYear: 2016\n\nAbstract: Rapid urbanization has led to more people residing in cities than ever before, and projections estimate that 64% of the global population will be urban by 2050. Cities are beginning to explore Smart City initiatives to reduce expenses and complexities while increasing efficiency and quality of life for its citizens. To achieve this goal, advances in technology and policies are needed together with rethinking traditional solutions to transportation, safety, sustainability, among other priority areas. We propose the use of a Smart Stadium as a 'living laboratory' to identify, deploy and test Internet of Things technologies and Smart City solutions in an environment small enough to practically trial but large enough to evaluate effectiveness and scalability. The Smart Stadium for Smarter Living initiative brings together Arizona State University, Dublin City University, Intel Corporation, Gaelic Athletic Association, Sun Devil Stadium and Croke Park to explore smart environment solutions.","Title: Enriching The Fan Experience In A Smart Stadium Using Internet Of Things Technologies\nYear: 2017\n\nAbstract: Rapid urbanization has brought about an influx of people to cities, tipping the scale between urban and rural living. Population predictions estimate that 64% of the global population will reside in cities by 2050. To meet the growing resource needs, improve management, reduce complexities, and eliminate unnecessary costs while enhancing the quality of life of citizens, cities are increasingly exploring open innovation frameworks and smart city initiatives that target priority areas including transportation, sustainability, and security. The size and heterogeneity of urban centers impede progress of technological innovations for smart cities. We propose a Smart Stadium as a living laboratory to balance both size and heterogeneity so that smart city solutions and Internet of Things (IoT) technologies may be deployed and tested within an environment small enough to practically trial but large and diverse enough to evaluate scalability and efficacy. The Smart Stadium for Smart Living initiative brings together multiple institutions and partners including Arizona State University (ASU), Dublin City University (DCU), Intel Corporation, and Gaelic Athletic Association (GAA), to turn ASU's Sun Devil Stadium and Ireland's Croke Park Stadium into twinned smart stadia to investigate IoT and smart city technologies and applications.","Title: ResnetCrowd: A residual deep learning architecture for crowd counting, violent behaviour detection and crowd density level classification\nYear: 2017\n\nAbstract: In this paper we propose ResnetCrowd, a deep residual architecture for simultaneous crowd counting, violent behaviour detection and crowd density level classification. To train and evaluate the proposed multi-objective technique, a new 100 image dataset referred to as Multi Task Crowd is constructed. This new dataset is the first computer vision dataset fully annotated for crowd counting, violent behaviour detection and density level classification. Our experiments show that a multi-task approach boosts individual task performance for all tasks and most notably for violent behaviour detection which receives a 9% boost in ROC curve AUC (Area under the curve). The trained ResnetCrowd model is also evaluated on several additional benchmarks highlighting the superior generalisation of crowd analysis models trained for multiple objectives.","Title: Automatic Detection of Knee Joints and Quantification of Knee Osteoarthritis Severity using Convolutional Neural Networks.\nYear: 2017\n\nAbstract: This paper introduces a new approach to automatically quantify the severity of knee OA using X-ray images. Automatically quantifying knee OA severity involves two steps: first, automatically localizing the knee joints; next, classifying the localized knee joint images. We introduce a new approach to automatically detect the knee joints using a fully convolutional neural network (FCN). We train convolutional neural networks (CNN) from scratch to automatically quantify the knee OA severity optimizing a weighted ratio of two loss functions: categorical cross-entropy and mean-squared loss. This joint training further improves the overall quantification of knee OA severity, with the added benefit of naturally producing simultaneous multi-class classification and regression outputs. Two public datasets are used to evaluate our approach, the Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis Study (MOST), with extremely promising results that outperform existing approaches.","Title: Semantic Indexing of Wearable Camera Images: Kids'Cam Concepts\nYear: 2016\n\nAbstract: In order to provide content-based search on image media, including images and video, they are typically accessed based on manual or automatically assigned concepts or tags, or sometimes based on image-image similarity depending on the use case. While great progress has been made in very recent years in automatic concept detection using machine learning, we are still left with a mis-match between the semantics of the concepts we can automatically detect, and the semantics of the words used in a user's query, for example. In this paper we report on a large collection of images from wearable cameras gathered as part of the Kids'Cam project, which have been both manually annotated from a vocabulary of 83 concepts, and automatically annotated from a vocabulary of 1,000 concepts. This collection allows us to explore issues around how language, in the form of two distinct concept vocabularies or spaces, one manually assigned and thus forming a ground-truth, is used to represent images, in our case taken using wearable cameras. It also allows us to discuss, in general terms, issues around mis-match of concepts in visual media, which derive from language mis-matches. We report the data processing we have completed on this collection and some of our initial experimentation in mapping across the two language vocabularies.","Title: MMHealth 2017: Workshop on Multimedia for Personal Health and Health Care.\nYear: 2018\n\nAbstract: The goal of the MMHealth 2017 Workshop on Multimedia for Personal Health and Health Care was to explore the relevance and contribution of multimedia in healthcare and personal health. After a successful debut in Amsterdam in 2016, the second workshop at ACM Multimedia 2017 in Mountain View, California, again attracted more than 30 participants, indicating the relevance that this topic has in the m...","Title: MedFit: A Mobile Application for Patients in CVD Recovery.\nYear: 2017\n\nAbstract: The third phase of the recovery from cardiovascular disease (CVD) is an exercise-based rehabilitation programme. However, adherence to an exercise regime is typically not maintained by the patient for a variety of reasons such as lack of time, financial constraints, etc. In order to facilitate patients to perform their exercises from the comfort of their home and at their own convenience, we have developed a mobile application, termed MedFit. It provides access to a tailored suite of exercises along with easy to understand guidance from audio and video instructions. Two types of wearable sensors are utilized to provide motivational feedback. Fitbit, a commercially available activity and fitness tracker, is used to provide in-depth feedback for self-monitoring over longer periods of time (e.g. day, week, month), whereas the Shimmer wireless sensing platform provides the data for near real-time feedback on the quality of the exercises performed. MedFit is a simple and intuitive mobile application designed to provide the motivation and tools for patients to help ensure faster recovery from the trauma caused by CVD. In this paper we describe features available in the MedFit application and the overall motivation behind the project.","Title: Saliency Weighted Convolutional Features for Instance Search\nYear: 2018\n\nAbstract: This work explores attention models to weight the contribution of local convolutional representations for the instance search task. We present a retrieval framework based on bags of local convolutional features (BLCF) that benefits from saliency weighting to build an efficient image representation. The use of human visual attention models (saliency) allows significant improvements in retrieval performance without the need to conduct region analysis or spatial verification, and without requiring any feature fine tuning. We investigate the impact of different saliency models, finding that higher performance on saliency benchmarks does not necessarily equate to improved performance when used in instance search tasks. The proposed approach outperforms the state-of-the-art on the challenging INSTRE benchmark by a large margin, and provides similar performance on the Oxford and Paris benchmarks compared to more complex methods that use off-the-shelf representations. Source code is publicly available at https:llgithub.com/imatge-upc/salbow.","Title: Understanding packet loss for sound monitoring in a smart stadium IoT testbed.\nYear: 2017\n\nAbstract: The Smart Stadium for Smarter Living project provides an end-to-end testbed for IoT innovation through a collaboration between Croke Park Stadium in Dublin, Ireland and Dublin City University, Intel and Microsoft. This enables practical evaluations of IoT solutions in a controlled environment that is small enough to conduct trials but large enough to prove and challenge the technologies. An evaluation of sound monitoring capabilities during the 2016 sporting finals was used to test the capture, transfer, storage and analysis of decibel level sound monitoring. The purpose of the evaluation was to use existing sound level microphones to measure crowd response to pre-determined events for display on big screens at half-time and to test the end-to-end performance of the testbed. While this is not the specific original purpose of the sound level microphones, it provided a useful test case and produced engaging content for the project. Analysis of the data streams showed significant packet loss during the events and further investigations were conducted to understand where and how this loss occurred. This paper describes the smart stadium testbed configuration using Intel gateways linking with the Azure cloud platform and analyses the performance of the system during the sound monitoring evaluation.","Title: Player detection in field sports.\nYear: 2018\n\nAbstract: We describe a method for player detection in field sports with a fixed camera setup based on a new player feature extraction strategy. The proposed method detects players in static images with a sliding window technique. First, we compute a binary edge image and then the detector window is shifted over the edge regions. Given a set of binary edges in a sliding window, we introduce and solve a particular diffusion equation to generate a shape information image. The proposed diffusion to generate a shape information image is the key stage and the main theoretical contribution in our new algorithm. It removes the appearance variations of an object while preserving the shape information. It also enables the use of polar and Fourier transforms in the next stage to achieve scale- and rotation-invariant feature extraction. A support vector machine classifier is used to assign either player or non-player class inside a detector window. We evaluate our approach on three different field hockey datasets. In general, results show that the proposed feature extraction is effective and performs competitive results compared to the state-of-the-art methods.","Title: Health Media: From Multimedia Signals to Personal Health Insights.\nYear: 2018\n\nAbstract: In this article, we explore the relevance and contribution of new signals in a broader interpretation of multimedia for personal health. We present how core multimedia research is becoming an important enabler for applications with the potential for significant societal impact.","Title: Automatic MOOC Video Classification using Transcript Features and Convolutional Neural Networks.\nYear: 2017\n\nAbstract: The amount of MOOC video materials has grown exponentially in recent years. Therefore, their storage and analysis need to be made as fully automated as possible in order to maintain their management quality. In this work, we present a method for automatic topic classification of MOOC videos using speech transcripts and convolutional neural networks (CNN). Our method works as follows: First, speech recognition is used to generate video transcripts. Then, the transcripts are converted into images using a statistical co-occurrence transformation that we designed. Finally, a CNN is used to produce video category labels for a transcript image input. For our data, we use the Khan Academy on a Stick dataset that contains 2,545 videos, where each video is labeled with one or two of 13 categories. Experiments show that our method is strongly competitive against other methods that are also based on transcript features and supervised learning.","Title: Temporal segmentation and recognition of team activities in sports\nYear: 2018\n\nAbstract: A method for temporal segmentation and recognition of team activities in sports, based on a new activity feature extraction, is presented. Given the positions of team players from a plan view of the playground at any given time, we generate a smooth distribution on the whole playground, termed the position distribution of the team. Computing the position distribution for each frame provides a sequence of distributions, which we process to extract motion features for activity recognition. We can classify six different team activities in European handball and eight different team activities in field hockey datasets. The field hockey dataset is a new, large and challenging dataset that is presented for the first time for continuous segmentation of team activities. Our approach is different from other trajectory-based methods. These methods extract activity features using the explicitly defined trajectories, where the players have specific positions. In our work, given the specific positions of the team players at a frame, we construct a position distribution for the team on the whole playground and process the sequence of position distribution images to extract activity features. Extensive evaluation and results show that our approach is effective.","Title: A comparison between end-to-end approaches and feature extraction based approaches for Sign Language recognition\nYear: 2017\n\nAbstract: In this paper we use a new image dataset for Irish Sign Language (ISL) and we compare different approaches for recognition. We perform experiments and report comparative accuracy and timing. We perform tests over blurred images and compare results with non-blurred images. For classification, we use end-to-end approaches, such as Convolutional Neural Networks (CNN) and feature based extraction approaches, such as Principal Component Analysis (PCA) followed by different classifiers, e.g. multilayer perceptron (MLP). We obtain a recognition accuracy over 99% for both approaches. In addition, we report different ways to split the training and testing dataset, one being iterative and the other randomly selected.","Title: Design and Development of the MedFit App: A Mobile Application for Cardiovascular Disease Rehabilitation.\nYear: 2017\n\nAbstract: Rehabilitation from cardiovascular disease (CVD) usually requires lifestyle changes, especially an increase in exercise and physical activity. However, uptake and adherence to exercise is low for community-based programmes. We propose a mobile application that allows users to choose the type of exercise and compete it at a convenient time in the comfort of their own home. Grounded in a behaviour change framework, the application provides feedback and encouragement to continue exercising and to improve on previous results. The application also utilizes wearable wireless technologies in order to provide highly personalized feedback. The application can accurately detect if a specific exercise is being done, and count the associated number of repetitions utilizing accelerometer or gyroscope signals Machine learning models are employed to recognize individual local muscular endurance (LME) exercises, achieving overall accuracy of more than 98%. This technology allows providing a near real-time personalized feedback which mimics the feedback that the user might expect from an instructor. This is provided to motivate users to continue the recovery process.","Title: HealthMedia 2018: Third International Workshop on Multimedia for Personal Health and Health Care.\nYear: 2018\n\nAbstract: Research in multimedia and health is driven by the current technological advancements in sensors and personalized healthcare. There is an increasing amount of work that shows how core multimedia research is becoming an important enabler for solutions with applications and relevance for the societal questions of health. This workshop brings together researchers from diverse topics such as multimedia, pervasive health, lifelogging, accessibility, HCI, but also health, medicine, and psychology to address challenges and opportunities of multimedia in and for health.","Title: Demonstration of an Open Source Framework for Qualitative Evaluation of CBIR Systems.\nYear: 2018\n\nAbstract: Evaluating image retrieval systems in a quantitative way, for example by computing measures like mean average precision, allows for objective comparisons with a ground-truth. However, in cases where ground-truth is not available, the only alternative is to collect feedback from a user. Thus, qualitative assessments become important to better understand how the system works. Visualizing the results could be, in some scenarios, the only way to evaluate the results obtained and also the only opportunity to identify that a system is failing. This necessitates developing a User Interface (UI) for a Content Based Image Retrieval (CBIR) system that allows visualization of results and improvement via capturing user relevance feedback. A well-designed UI facilitates understanding of the performance of the system, both in cases where it works well and perhaps more importantly those which highlight the need for improvement. Our open-source system implements three components to facilitate researchers to quickly develop these capabilities for their retrieval engine. We present: a web-based user interface to visualize retrieval results and collect user annotations; a server that simplifies connection with any underlying CBIR system; and a server that manages the search engine data. The software itself is described in a separate submission to the ACM MM Open Source Software Competition.","Title: A Deep Residual Architecture For Skin Lesion Segmentation\nYear: 2018\n\nAbstract: In this paper, we propose an automatic approach to skin lesion region segmentation based on a deep learning architecture with multi-scale residual connections. The architecture of the proposed model is based on UNet [22] with residual connections to maximise the learning capability and performance of the network. The information lost in the encoder stages due to the max-pooling layer at each level is preserved through the multi-scale residual connections. To corroborate the efficacy of the proposed model, extensive experiments are conducted on the ISIC 2017 challenge dataset without using any external dermatologic image set. An extensive comparative analysis is presented with contemporary methodologies to highlight the promising performance of the proposed methodology.","Title: Automatic Estimation of Enjoyment Levels during Cardiac Rehabilitation Exercise.\nYear: 2018\n\nAbstract: Cardiovascular disease (CVD) is the leading cause of premature death and disability in Europe and worldwide. Effective Cardiac Rehabilitation (CR) can significantly improve mortality and morbidity rates, leading to longer independent living and a reduced use of health care resources. However, adherence to such an exercise programme is generally low for a variety of reasons such as lack of time and how enjoyable the CR programme is. In this work, we proposed a method for automatic enjoyment estimation during an exercise which could be used by a clinician to identify when a patient is not enjoying the exercise and therefore at risk of early dropout. In order to evaluate the proposed method, a database was captured where participants perform various of CR exercises. Three set of facial features were extracted and were evaluated using seven different classifiers. The proposed method achieved 49% average accuracy in predicting five different enjoyment level on the newly collected database.","Title: A Residual Encoder-Decoder Network for Semantic Segmentation in Autonomous Driving Scenarios.\nYear: 2018\n\nAbstract: In this paper, we propose an encoder-decoder based deep convolutional network for semantic segmentation in autonomous driving scenarios. The architecture of the proposed model is based on VGG16 [1]. Residual learning is introduced to preserve the context while decreasing the size of feature maps between the stacks of convolutional layers. Also, the resolution is preserved through shortcuts from the encoder stage to the decoder stage. Experiments are conducted on popular benchmark datasets CamVid and CityScapes to demonstrate the efficacy of the proposed model. The experiments are corroborated with comparative analysis with popular encoder-decoder networks such as SegNet and Enet architectures demonstrating that the proposed approach outperforms existing methods despite having fewer trainable parameters.","Title: Exploring the Impact of Training Data Bias on Automatic Generation of Video Captions.\nYear: 2019\n\nAbstract: A major issue in machine learning is availability of training data. While this historically referred to the availability of a sufficient volume of training data, recently this has shifted to the availability of sufficient unbiased training data. In this paper we focus on the effect of training data bias on an emerging multimedia application, the automatic captioning of short video clips. We use subsets of the same training data to generate different models for video captioning using the same machine learning technique and we evaluate the performances of different training data subsets using a well-known video caption benchmark, TRECVid. We train using the MSR-VTT video-caption pairs and we prune this to reduce and make the set of captions describing a video more homogeneously similar, or more diverse, or we prune randomly. We then assess the effectiveness of caption-generating trained with these variations using automatic metrics as well as direct assessment by human assessors. Our findings are preliminary and show that randomly pruning captions from the training data yields the worst performance and that pruning to make the data more homogeneous, or diverse, does improve performance slightly when compared to random. Our work points to the need for more training data, both more video clips but, more importantly, more captions for those videos.","Title: Towards An \"Ethics By Design\" Methodology For Ai Research Projects\nYear: 2018\n\nAbstract: Addressing ethical issues arising from AI research, and by extension from most areas of Data Science, is a core challenge in both the academic and industry worlds. The nature of research and the specific set of technical skills involved imply that AI and Data Science researchers are not equipped to identify and anticipate such issues arising, or to establish solutions at the time a specific research project is being designed. In this paper, we discuss the need for a methodology for ethical research design that involves a broader set of skills from the start of the project. We specifically identify, from the relevant literature, a set of requirements that we argue to be needed for such a methodology. We then explore two case studies where such ethical considerations have been explored in conjunction with the development of specific research projects, in order to validate those assumptions and generalise them into a set of principles guiding an \"Ethics by Design\" method for conducting AI and Data Science research.","Title: Abnormal crowd behavior detection using novel optical flow-based features\nYear: 2017\n\nAbstract: In this paper, we propose a novel optical flow based features for abnormal crowd behaviour detection. The proposed feature is mainly based on the angle difference computed between the optical flow vectors in the current frame and in the previous frame at each pixel location. The angle difference information is also combined with the optical flow magnitude to produce new, effective and direction invariant event features. A one-class SVM is utilized to learn normal crowd behavior. If a test sample deviates significantly from the normal behavior, it is detected as abnormal crowd behavior. Although there are many optical flow based features for crowd behaviour analysis, this is the first time the angle difference between optical flow vectors in the current frame and in the previous frame is considered as a anomaly feature. Evaluations on UMN and PETS2009 datasets show that the proposed method performs competitive results compared to the state-of-the-art methods.","Title: Action localization in video using a graph-based feature representation\nYear: 2017\n\nAbstract: We propose a new framework for human action localization in video sequences. The option to not only detect but also localize actions in surveillance video is crucial to improving system's ability to manage high volumes of CCTV. In the approach, the action localization task is formulated the maximum-path finding problem in the directed spatio-temporal video-graph. The graph is constructed on the top of frame and temporal-based low-level features. To localize actions in the video-graph, we apply a maximum-path algorithm to find the path in the graph that is considered to be the localized action in the video. The proposed approach achieves competitive performance with the J-HMDB and the UCF-Sports dataset.","Title: A Text Recognition and Retrieval System for e-Business Image Management.\nYear: 2018\n\nAbstract: The on-going growth of e-business has resulted in companies having to manage an ever increasing number of product, packaging and promotional images. Systems for indexing and retrieving such images are required in order to ensure image libraries can be managed and fully exploited as valuable business resources. In this paper, we explore the power of text recognition for e-business image management and propose an innovative system based on photo OCR. Photo OCR has been actively studied for scene text recognition but has not been exploited for e-business digital image management. Besides the well known difficulties in scene text recognition such as various size, location, orientation in text and cluttered background, e-business images typically feature text with extremely diverse fonts, and the characters are often artistically modified in shape, colour and arrangement. To address these challenges, our system takes advantage of the combinatorial power of deep neural networks and MSER processing. The cosine distance and n-gram vectors are used during retrieval for matching detected text to queries to provide tolerance to the inevitable transcription errors in text recognition. To evaluate our proposed system, we prepared a novel dataset designed specifically to reflect the challenges associated with text in e-business images. We compared our system with two other approaches for scene text recognition, and the results show our system outperforms other state-of-the-art on the new challenging dataset. Our system demonstrates that recognizing text embedded in images can be hugely beneficial for digital asset management.","Title: Educational video classification by using a transcript to image transform and supervised learning\nYear: 2017\n\nAbstract: In this work, we present a method for automatic topic classification of educational videos using a speech transcript transform. Our method works as follows: First, speech recognition is used to generate video transcripts. Then, the transcripts are converted into images using a statistical cooccurrence transformation that we designed. Finally, a classifier is used to produce video category labels for a transcript image input. For our classifiers, we report results using a convolutional neural network (CNN) and a principal component analysis (PCA) model. In order to evaluate our method, we used the Khan Academy on a Stick dataset that contains 2,545 videos, where each video is labeled with one or two of 13 categories. Experiments show that our method is effective and strongly competitive against other supervised learning-based methods.","Title: A novel shape descriptor based on salient keypoints detection for binary image matching and retrieval.\nYear: 2018\n\nAbstract: We introduce a shape descriptor that extracts keypoints from binary images and automatically detects the salient ones among them. The proposed descriptor operates as follows: First, the contours of the image are detected and an image transformation is used to generate background information. Next, pixels of the transformed image that have specific characteristics in their local areas are used to extract keypoints. Afterwards, the most salient keypoints are automatically detected by filtering out redundant and sensitive ones. Finally, a feature vector is calculated for each keypoint by using the distribution of contour points in its local area. The proposed descriptor is evaluated using public datasets of silhouette images, handwritten math expressions, hand-drawn diagram sketches, and noisy scanned logos. Experimental results show that the proposed descriptor compares strongly against state of the art methods, and that it is reliable when applied on challenging images such as fluctuated handwriting and noisy scanned images. Furthermore, we integrate our descriptor in a content-based document image retrieval system using sketch queries as a step for query and candidate occurrence matching, and we show that it leads to a significant boost in retrieval performances.","Title: Scanpath and saliency prediction on 360 degree images.\nYear: 2018\n\nAbstract: We introduce deep neural networks for scanpath and saliency prediction trained on 360-degree images. The scanpath prediction model called SaltiNet is based on a temporal-aware novel representation of saliency information named the saliency volume. The first part of the network consists of a model trained to generate saliency volumes, whose parameters are fit by back-propagation using a binary cross entropy (BCE) loss over downsampled versions of the saliency volumes. Sampling strategies over these volumes are used to generate scanpaths over the 360-degree images. Our experiments show the advantages of using saliency volumes, and how they can be used for related tasks. We also show how a similar architecture achieves state-of-the-art performance for the related task of saliency map prediction. Our source code and trained models available at https://github.com/massens/saliency-360salient-2017.","Title: SaltiNet: Scan-path Prediction on 360 Degree Images using Saliency Volumes.\nYear: 2017\n\nAbstract: We introduce SaltiNet, a deep neural network for scan-path prediction trained on 360-degree images. The model is based on a temporal-aware novel representation of saliency information named the saliency volume. The first part of the network consists of a model trained to generate saliency volumes, whose parameters are fit by back-propagation computed from a binary cross entropy (BCE) loss over downsampled versions of the saliency volumes. Sampling strategies over these volumes are used to generate scan-paths over the 360-degree images. Our experiments show the advantages of using saliency volumes, and how they can be used for related tasks. Our source code and trained models available at https://github.com/massens/saliency-360salient-2017.","Title: A Low-Cost Smart Sensor Network for Catchment Monitoring.\nYear: 2019\n\nAbstract: Understanding hydrological processes in large, open areas, such as catchments, and further modelling these processes are still open research questions. The system proposed in this work provides an automatic end-to-end pipeline from data collection to information extraction that can potentially assist hydrologists to better understand the hydrological processes using a data-driven approach. In this work, the performance of a low-cost off-the-shelf self contained sensor unit, which was originally designed and used to monitor liquid levels, such as AdBlue, fuel, lubricants etc., in a sealed tank environment, is first examined. This process validates that the sensor does provide accurate water level information for open water level monitoring tasks. Utilising the dataset collected from eight sensor units, an end-to-end pipeline of automating the data collection, data processing and information extraction processes is proposed. Within the pipeline, a data-driven anomaly detection method that automatically extracts rapid changes in measurement trends at a catchment scale. The lag-time of the test site (Dodder catchment Dublin, Ireland) is also analyzed. Subsequently, the water level response in the catchment due to storm events during the 27 month deployment period is illustrated. To support reproducible and collaborative research, the collected dataset and the source code of this work will be publicly available for research purposes.","Title: An evaluation of a 3D multimodal marker-less motion analysis system\nYear: 2019\n\nAbstract: Motion analysis is a technique used by clinicians (among many others) that quantifies human movement by using camera-based systems. Marker-based motion analysis systems have been used across a variety of application domains, from Interactive 3D Tele-Immersion (i3DTI) environments to the diagnosis of neuromuscular and musculoskeletal diseases. Although such analysis is performed in several laboratories in many countries, numerous issues exist: (1) the high cost of precise motion capture systems; (2) scarcity of qualified personnel to operate them; (3) expertise required to interpret their results; (4) space requirements to install and store these systems; (5) complexity in terms of measurement protocol required for such systems; (6) limited availability; (7) and in some situations the use of markers means they are unsuitability for certain clinical use cases (e.g. for patients recovering from orthopaedic surgery). In this paper, we present, from a system perspective, an alternative, cheaper, and more accessible system for motion analysis. The ultimate aim is to use the output of this multimodal marker-less system as part of an immersive multimedia gait re-education tool. In real-time, it will advise the user on their gait performance (as well as potentially providing accurate clinical data to clinicians). With the initial focus on the capture system, we have developed and evaluated a novel multimodal system which integrates Multiple Microsoft Kinects (which employ RGB-D cameras) with multiple Shimmer Inertial Measurement Unit (IMU) sensors. We have compared this system with the VICON system (the gold standard in motion capture). Our marker-less motion capture system combines data from 4 skeletons generating 3D and complete 360 degrees in view skeleton. The system combines unit quaternions from each Kinect joint with quaternions from 4 inertial measurement units to promote integration. We used our system to measure 3D points of 12 joints from the Kinect fused skeleton and flexion-extension angles of the knee and hip in a walking trial in 8 participants with 8--10 trials per participant. The analysis found component similarity of 0.97 for knee angles and 0.98 for hip angles. These results show that our system, through combination of Multi Kinect system and Shimmer IMUs, offers a cheaper, sufficiently accurate and more accessible human motion analysis system.","Title: Unsupervised label noise modeling and loss correction\nYear: 2019\n\nAbstract: Despite being robust to small amounts of label noise, convolutional neural networks trained with stochastic gradient methods have been shown to easily fit random labels. When there are a mixture of correct and mislabelled targets, networks tend to fit the former before the latter. This suggests using a suitable two-component mixture model as an unsupervised generative model of sample loss values during training to allow online estimation of the probability that a sample is mislabelled. Specifically, we propose a beta mixture to estimate this probability and correct the loss by relying on the network prediction (the so-called bootstrapping loss). We further adapt mixup augmentation to drive our approach a step further. Experiments on CIFAR-10/100 and TinyImageNet demonstrate a robustness to label noise that substantially outperforms recent state-of-the-art. Source code is available at this https URL","Title: On guiding video object segmentation\nYear: 2019\n\nAbstract: This paper presents a novel approach for segmenting moving objects in unconstrained environments using guided convolutional neural networks. This guiding process relies on foreground masks from independent algorithms (i.e. state-of-the-art algorithms) to implement an attention mechanism that incorporates the spatial location of foreground and background to compute their separated representations. Our approach initially extracts two kinds of features for each frame using colour and optical flow information. Such features are combined following a multiplicative scheme to benefit from their complementarity. These unified colour and motion features are later processed to obtain the separated foreground and background representations. Then, both independent representations are concatenated and decoded to perform foreground segmentation. Experiments conducted on the challenging DAVIS 2016 dataset demonstrate that our guided representations not only outperform non-guided, but also recent and top-performing video object segmentation algorithms.","Title: Assessing Knee OA Severity with CNN attention-based end-to-end architectures.\nYear: 2019\n\nAbstract: This work proposes a novel end-to-end convolutional neural network (CNN) architecture to automatically quantify the severity of knee osteoarthritis (OA) using X-Ray images, which incorporates trainable attention modules acting as unsupervised fine-grained detectors of the region of interest (ROI). The proposed attention modules can be applied at different levels and scales across any CNN pipeline helping the network to learn relevant attention patterns over the most informative parts of the image at different resolutions. We test the proposed attention mechanism on existing state-of-the-art CNN architectures as our base models, achieving promising results on the benchmark knee OA datasets from the osteoarthritis initiative (OAI) and multicenter osteoarthritis study (MOST).","Title: Open-Source: Attention-Based Neural Networks For Chroma Intra Prediction In Video Coding\nYear: 2021\n\nAbstract: Neural networks can be successfully used to improve several modules of advanced video coding schemes. In particular, compression of colour components was shown to greatly benefit from usage of machine learning models, thanks to the design of appropriate attention-based architectures that allow the prediction to exploit specific samples in the reference region. However, such architectures tend to b...","Title: Guest Editorial Special Section on IEEE ICME 2020\nYear: 2021\n\nAbstract: This special section contains extended versions of papers presented at the IEEE International Conference on Multimedia & Expo (ICME) in London, July 2020. The invitations to contribute to the special section were based on the quality of the conference paper and its relevance to the aims and scope of the journal. Each submitted manuscript was reviewed by at least three anonymous reviewers. After a rigorous review process, three papers were accepted. Two of them present new developments in immersive media, while the third deals with the problem of efficiently encoding a deep neural network.","Title: How Important is Importance Sampling for Deep Budgeted Training?\nYear: 2021\n\nAbstract: Long iterative training processes for Deep Neural Networks (DNNs) are commonly required to achieve state-of-the-art performance in many computer vision tasks. Importance sampling approaches might play a key role in budgeted training regimes, i.e. when limiting the number of training iterations. These approaches aim at dynamically estimating the importance of each sample to focus on the most relevant and speed up convergence. This work explores this paradigm and how a budget constraint interacts with importance sampling approaches and data augmentation techniques. We show that under budget restrictions, importance sampling approaches do not provide a consistent improvement over uniform sampling. We suggest that, given a specific budget, the best course of action is to disregard the importance and introduce adequate data augmentation; e.g. when reducing the budget to a 30% in CIFAR-10/100, RICAP data augmentation maintains accuracy, while importance sampling does not. We conclude from our work that DNNs under budget restrictions benefit greatly from variety in the training set and that finding the right samples to train on is not the most effective strategy when balancing high performance with low computational requirements. Source code available at https://git.io/JKHa3 .","Title: Rethinking 360° Image Visual Attention Modelling with Unsupervised Learning.\nYear: 2021\n\nAbstract: Despite the success of self-supervised representation learning on planar data, to date it has not been studied on 360deg images. In this paper, we extend recent advances in contrastive learning to learn latent representations that are sufficiently invariant to be highly effective for spherical saliency prediction as a downstream task. We argue that omni-directional images are particularly suited to such an approach due to the geometry of the data domain. To verify this hypothesis, we design an unsupervised framework that effectively maximizes the mutual information between the different views from both the equator and the poles. We show that the decoder is able to learn good quality saliency distributions from the encoder embeddings. Our model compares favorably with fully-supervised learning methods on the Salient360!, VR-EyeTracking and Sitzman datasets. This performance is achieved using an encoder that is trained in a completely unsupervised way and a relatively lightweight supervised decoder (3.8 X fewer parameters in the case of the ResNet50 encoder). We believe that this combination of supervised and unsupervised learning is an important step toward flexible formulations of human visual attention.","Title: UrbanAccess: Query Driven Urban Analytics Platform for Detecting Complex Accessibility Event Patterns using Tactile Surfaces\nYear: 2021\n\nAbstract: BSTRACTThe smart city concept has now become one of the key enablers in urban city management. The adoption and permeation of ICT and AI-driven techniques have enabled the authorities to resolve poor urban planning issues with improved delivery of citizen services. Major urban problem is addressing the accessibility issue across cities road crossing and facilitating visually impaired people via well-defined infrastructure. The research presented in this paper emphasized urban analytics that studies the road crossings and challenges one faces when accessing the footpaths of a city using the Tactile surfaces. This work demonstrates a distributed event analytics platform- GNOSIS to detect complex accessibility event patterns. GNOSIS ingest video data streams from cities infrastructure such as CCTV and detect tactile surface event patterns using an ensemble of deep learning models using a declarative query language. The work analyzes mainly three types of tactile surface - Blister, Cycleway and Directional, collected from different cities in Ireland using crowd-sourcing techniques. GNOSIS makes decisions in real-time based on the type of tactile surface, colour and the making pattern.","Title: Simple baselines can fool 360 degrees saliency metrics\nYear: 2021\n\nAbstract: Evaluating a model's capacity to predict human fixations in 360 degrees scenes is a challenging task. 360 degrees saliency requires different assumptions compared to 2D as a result of the way the saliency maps are collected and pre-processed to account for the difference in statistical bias (Equator vs Center bias). However, the same classical metrics from the 2D saliency literature are typically used to evaluate 360 degrees models. In this paper, we show that a simple constant predictor, i.e. the average map across Salient360 and Sitzman training sets can fool existing metrics and achieve results on par with specialized models. Thus, we propose a new probabilistic metric based on the independent Bernoullis assumption that is more suited to the 360 degrees saliency task.","Title: BERTHA: Video Captioning Evaluation Via Transfer-Learned Human Assessment.\nYear: 2022\n\nAbstract: Evaluating video captioning systems is a challenging task as there are multiple factors to consider; for instance: the fluency of the caption, multiple actions happening in a single scene, and the human bias of what is considered important. Most metrics try to measure how similar the system generated captions are to a single or a set of human-annotated captions. This paper presents a new method based on a deep learning model to evaluate these systems. The model is based on BERT, which is a language model that has been shown to work well in multiple NLP tasks. The aim is for the model to learn to perform an evaluation similar to that of a human. To do so, we use a dataset that contains human evaluations of system generated captions. The dataset consists of the human judgments of the captions produce by the system participating in various years of the TRECVid video to text task. These annotations will be made publicly available. BERTHA obtain favourable results, outperforming the commonly used metrics in some setups.","Title: On the Use of 3D CNNs for Video Saliency Modeling\nYear: 2020\n\nAbstract: There has been emerging interest recently in three dimensional (3D) convolutional neural networks (CNNs) as a powerful tool to encode spatiotemporal representations in videos, by adding a third temporal dimension to preexisting 2D CNNs. In this chapter, we discuss the effectiveness of using 3D convolutions to capture the important motion features in the context of video saliency prediction. The method filters the spatio-temporal features across multiple adjacent frames. This cubic convolution could be effectively applied on a dense sequence of frames propagating the previous frames' information into the current, reflecting processing mechanisms of the human visual system for better saliency prediction. We extensively evaluate the model performance compared to the state-of-the-art video saliency models on both 2D and 360 degrees videos. The architecture can efficiently learn expressive spatio-temporal representations and produce high quality video saliency maps on three large-scale 2D datasets, DHF1K, UCF-SPORTS and DAVIS. Investigations on the 360 degrees Salient360! and datasets show how the approach can generalise.","Title: Domain Randomization for Object Counting.\nYear: 2021\n\nAbstract: Recently, the use of synthetic datasets based on game engines has been shown to improve the performance of several tasks in computer vision. However, these datasets are typically only appropriate for the specific domains depicted in computer games, such as urban scenes involving vehicles and people. In this paper, we present an approach to generate synthetic datasets for object counting for any domain without the need for photo-realistic techniques manually generated by expensive teams of 3D artists. We introduce a domain randomization approach for object counting based on synthetic datasets that are quick and inexpensive to generate. We deliberately avoid photorealism and drastically increase the variability of the dataset, producing images with random textures and 3D transformations, which improves generalization. Experiments show that our method facilitates good performance on various real word object counting datasets for multiple domains: people, vehicles, penguins, and fruit. The source code is available at: https://github.com/enric1994/dr4oc","Title: Synthetic Data for Unsupervised Polyp Segmentation.\nYear: 2021\n\nAbstract: Deep learning has shown excellent performance in analysing medical images. However, datasets are difficult to obtain due privacy issues, standardization problems, and lack of annotations. We address these problems by producing realistic synthetic images using a combination of 3D technologies and generative adversarial networks. We use zero annotations from medical professionals in our pipeline. Our fully unsupervised method achieves promising results on five real polyp segmentation datasets. As a part of this study we release Synth-Colon, an entirely synthetic dataset that includes 20000 realistic colon images and additional details about depth and 3D geometry: https://enric1994.github.io/synth-colon","Title: Unsupervised domain adaptation and super resolution on drone images for autonomous dry herbage biomass estimation\nYear: 2022\n\nAbstract: Herbage mass yield and composition estimation is an important tool for dairy farmers to ensure an adequate supply of high quality herbage for grazing and subsequently milk production. By accurately estimating herbage mass and composition, targeted nitrogen fertiliser application strategies can be deployed to improve localised regions in a herbage field, effectively reducing the negative impacts of over-fertilization on biodiversity and the environment. In this context, deep learning algorithms offer a tempting alternative to the usual means of sward composition estimation, which involves the destructive process of cutting a sample from the herbage field and sorting by hand all plant species in the herbage. The process is labour intensive and time consuming and so not utilised by farmers. Deep learning has been successfully applied in this context on images collected by high-resolution cameras on the ground. Moving the deep learning solution to drone imaging, however, has the potential to further improve the herbage mass yield and composition estimation task by extending the ground-level estimation to the large surfaces occupied by fields/paddocks. Drone images come at the cost of lower resolution views of the fields taken from a high altitude and requires further herbage ground-truth collection from the large surfaces covered by drone images. This paper proposes to transfer knowledge learned on ground-level images to raw drone images in an unsupervised manner. To do so, we use unpaired image style translation to enhance the resolution of drone images by a factor of eight and modify them to appear closer to their ground-level counterparts. We then use the enhanced drone images to train a semi-supervised algorithm that uses ground-truthed, ground-level images as the labelled data together with a large amount of unlabeled drone images. We validate our results on a small held-out drone image test set to show the validity of our approach, which opens the way for automated dry herbage biomass monitoring www.github.com/PaulAlbert31/Clover_SSL.","Title: Attention-based Stylisation for Exemplar Image Colourisation\nYear: 2021\n\nAbstract: Exemplar-based colourisation aims to add plausible colours to a grayscale image using the guidance of a colour reference image. Most existing methods tackle the task as a style transfer problem, using a convolutional neural network (CNN) to obtain deep representations of the content of both inputs. Stylised outputs are then obtained by computing similarities between both feature representations in...","Title: Embedding Contrastive Unsupervised Features to Cluster In- And Out-of-Distribution Noise in Corrupted Image Datasets.\nYear: 2022\n\nAbstract: Using search engines for web image retrieval is a tempting alternative to manual curation when creating an image dataset, but their main drawback remains the proportion of incorrect (noisy) samples retrieved. These noisy samples have been evidenced by previous works to be a mixture of in-distribution (ID) samples, assigned to the incorrect category but presenting similar visual semantics to other classes in the dataset, and out-of-distribution (OOD) images, which share no semantic correlation with any category from the dataset. The latter are, in practice, the dominant type of noisy images retrieved. To tackle this noise duality, we propose a two stage algorithm starting with a detection step where we use unsupervised contrastive feature learning to represent images in a feature space. We find that the alignment and uniformity principles of contrastive learning allow OOD samples to be linearly separated from ID samples on the unit hypersphere. We then spectrally embed the unsupervised representations using a fixed neighborhood size and apply an outlier sensitive clustering at the class level to detect the clean and OOD clusters as well as ID noisy outliers. We finally train a noise robust neural network that corrects ID noise to the correct category and utilizes OOD samples in a guided contrastive objective, clustering them to improve low-level features. Our algorithm improves the state-of-the-art results on synthetic noise image datasets as well as real-world web-crawled data. Our work is fully reproducible github.com/PaulAlbert31/SNCF.","Title: An Evaluation of 360° Video and Audio Quality in an Artistic-Oriented Platform\nYear: 2022\n\nAbstract: Consuming immersive content over a browser is possible due to libraries such as WebGL, WebXR and Three.js. 360° videos, however, are very large in size, and high definition content can cause buffering events even in environments with high bandwidth. Immersiveness is further achieved in 360° content delivery with the addition of ambisonic audio, which indicates the source of sound, according to head tracking of users, in the 3-D space. In situations where video quality needs to be reduced due to network constraints, ambisonics can help increase user-perceived quality. This paper introduces a study of user experience with 24 participants located in various countries considering multiple quality levels of audio and video. An artistic-oriented platform for opera delivery is also described, in the context of the European Horizon 2020 TRACTION project.","Title: Incorporating Spatio-Temporal Information in Frustum-ConvNet for Improved 3D Object Detection in Instrumented Vehicles\nYear: 2022\n\nAbstract: Environmental perception is a key task for autonomous vehicles to ensure intelligent planning and safe decision-making. Most current state-of-the-art perceptual methods in vehicles, and in particular for 3D object detection, are based on a single-frame reference. However, these methods do not effectively utilise temporal information associated with the objects or the scene from the input data sequences. The work presented in this paper corroborates the use of spatial and temporal information through multi-frame, lidar, point cloud data to leverage spatio-temporal contextual information and improve the accuracy of 3D object detection. The study also gathers more insights into the effect of inducing temporal information into a network and the overall performance of the deep learning model. We consider the Frustum-ConvNet architecture as the baseline model and propose methods to incorporate spatio-temporal information using convolutional-LSTMs to detect the 3D object detection using lidar data. We also propose to employ an attention mechanism with temporal encoding to stimulate the model to focus on salient feature points within the region proposals. The results from this study shows the inclusion of temporal information considerably improves the true positive metric specifically the orientation error of the 3D bounding box from 0.819 to 0.784 and 0.294 to 0.111 for cars and pedestrian classes respectively on the customized subset of nuScenes training dataset. The overall nuScenes detection score (NDS) is improved from 0.822 to 0.837 compared to the baseline."],"string":"[\n \"Title: A Low-Cost Head and Eye Tracking System for Realistic Eye Movements in Virtual Avatars\\nYear: 2014\\n\\nAbstract: A virtual avatar or autonomous agent is a digital representation of a human being that can be controlled by either a human or an artificially intelligent computer system. Increasingly avatars are becoming realistic virtual human characters that exhibit human behavioral traits, body language and eye and head movements. As the interpretation of eye and head movements represents an important part of nonverbal human communication it is extremely important to accurately reproduce these movements in virtual avatars to avoid falling into the well-known \\\\\\\"uncanny valley\\\\\\\". In this paper we present a cheap hybrid real-time head and eye tracking system based on existing open source software and commonly available hardware. Our evaluation indicates that the system of head and eye tracking is stable and accurate and can allow a human user to robustly puppet a virtual avatar, potentially allowing us to train an A.I. system to learn realistic human head and eye movements.\",\n \"Title: Inexpensive fusion methods for enhancing feature detection\\nYear: 2007\\n\\nAbstract: Recent successful approaches to high-level feature detection in image and video data have treated the problem as a pattern classification task. These typically leverage the techniques learned from statistical machine learning, coupled with ensemble architectures that create multiple feature detection models. Once created, co-occurrence between learned features can be captured to further boost performance. At multiple stages throughout these frameworks, various pieces of evidence can be fused together in order to boost performance. These approaches whilst very successful are computationally expensive, and depending on the task, require the use of significant computational resources. In this paper we propose two fusion methods that aim to combine the output of an initial basic statistical machine learning approach with a lower-quality information source, in order to gain diversity in the classified results whilst requiring only modest computing resources. Our approaches, validated experimentally on TRECVid data, are designed to be complementary to existing frameworks and can be regarded as possible replacements for the more computationally expensive combination strategies used elsewhere.\",\n \"Title: Automated annotation of landmark images using community contributed datasets and web resources\\nYear: 2010\\n\\nAbstract: A novel solution to the challenge of automatic image annotation is described. Given an image with GPS data of its location of capture, our system returns a semantically-rich annotation comprising tags which both identify the landmark in the image, and provide an interesting fact about it, e.g. \\\"A view of the Eiffel Tower, which was built in 1889 for an international exhibition in Paris\\\". This exploits visual and textual web mining in combination with content-based image analysis and natural language processing. In the first stage, an input image is matched to a set of community contributed images (with keyword tags) on the basis of its GPS information and image classification techniques. The depicted landmark is inferred from the keyword tags for the matched set. The system then takes advantage of the information written about landmarks available on the web at large to extract a fact about the landmark in the image. We report component evaluation results from an implementation of our solution on a mobile device. Image localisation and matching offers 93.6% classification accuracy; the selection of appropriate tags for use in annotation performs well (F1M of 0.59), and it subsequently automatically identifies a correct toponym for use in captioning and fact extraction in 69.0% of the tested cases; finally the fact extraction returns an interesting caption in 78% of cases.\",\n \"Title: Dual-sensor fusion for indoor user localisation\\nYear: 2011\\n\\nAbstract: In this paper we address the automatic identification of indoor locations using a combination of WLAN and image sensing. Our motivation is the increasing prevalence of wearable cameras, some of which can also capture WLAN data. We propose to use image-based and WLAN-based localization individually and then fuse the results to obtain better performance overall. We demonstrate the effectiveness of our fusion algorithm for localisation to within a 8.9m2 room on very challenging data both for WLAN and image-based algorithms. We envisage the potential usefulness of our approach in a range of ambient assisted living applications.\",\n \"Title: Multimodal Identification of Journeys\\nYear: 2010\\n\\nAbstract: Due to the ubiquity of localisation technology, users now have the ability to keep a record of their own location, as a kind of ‘location diary’. Such a large collection of data can become unmanageable without some way to structure that data to make it useful and searchable. We address this problem of structuring location data by proposing a framework for classifying the data into often-traversed routes. In this work, commonly traversed routes are identified with clusters based on sensed data. Our framework does not rely on any one source of location information, but can fuse data from multimodal localisation sources. We demonstrate the effectiveness of our algorithm by examining the combination of GPS, wireless signal strength readings and image-matching on very challenging data in a variety of environmental conditions. By fusing these three modalities we obtained better performance than any individual or combination of two modalities. As it can be orientated towards the needs and capabilities of the user based on context, this method becomes useful for some ambient assisted living applications.\",\n \"Title: Exploiting contextual data for event retrieval in surveillance video\\nYear: 2009\\n\\nAbstract: Contextual information is vital for the robust extraction of semantic information in automated surveillance systems. We have developed a scene independent framework for the detection of events in which we provide 2D and 3D contextual data for the scene under surveillance via a novel fast and convenient interface tool. In addition, the proposed framework illustrates the use of integral images, not only for detection, as with the classic Viola-Jones object detector, but also for efficient tracking. Finally, we provide a quantitative assessment of the performance of the proposed system in a number of physical locations via groundtruthed datasets.\",\n \"Title: Passively recognising human activities through lifelogging\\nYear: 2011\\n\\nAbstract: Lifelogging is the process of automatically recording aspects of one's life in digital form. This includes visual lifelogging using wearable cameras such as the SenseCam and in recent years many interesting applications for this have emerged and are being actively researched. One of the most interesting of these, and possibly the most far-reaching, is using visual lifelogs as a memory prosthesis but there are also applications in job-specific activity recording, general lifestyle analysis and market analysis. In this work we describe a technique which allowed us to develop automatic classifiers for visual lifelogs to infer different lifestyle traits or characteristics. Their accuracy was validated on a set of 95k manually annotated images and through one-on-one interviews with those who gathered the images. These automatic classifiers were then applied to a collection of over 3million lifelog images collected by 33 individuals sporadically over a period of 3.5years. From this collection we present a number of anecdotal observations to demonstrate the future potential of lifelogging to capture human behaviour. These anecdotes include: the eating habits of office workers; to the amount of time researchers spend outdoors through the year; to the observation that retired people in our study appear to spend quite a bit of time indoors eating with friends. We believe this work demonstrates the potential of lifelogging techniques to assist behavioural scientists in future.\",\n \"Title: Automatic Summarization of Rushes Video Using Bipartite Graphs\\nYear: 2010\\n\\nAbstract: In this paper we present a new approach for automatic summarization of rushes video. Our approach is composed of three main steps. First, based on a temporal segmentation, we filter sub-shots with low information content not likely to be useful in a summary. Second, a method using maximal matching in a bipartite graph is adapted to measure similarity between the remaining shots and to minimize inter-shot redundancy by removing repetitive retake shots common in rushes content. Finally, the presence of faces and the motion intensity are characterised in each sub-shot. A measure of how representative the sub-shot is in the context of the overall video is then proposed. Video summaries composed of keyframe slideshows are then generated. In order to evaluate the effectiveness of this approach we re-run the evaluation carried out by the TREC, using the same dataset and evaluation metrics used in the TRECVID video summarization task in 2007 but with our own assessors. Results show that our approach leads to a significant improvement in terms of the fraction of the TRECVID summary ground truth included and is competitive with other approaches in TRECVID 2007.\",\n \"Title: Enhancing the Functionality of Interactive TV with Content-Based Multimedia Analysis\\nYear: 2009\\n\\nAbstract: In this paper we describe how content-based analysis techniques can be used to provide much greater functionality to the users of an interactive TV (iTV) device. We describe several content-based multimedia analysis techniques and how some of these can be exploited in the iTV domain, resulting in the provision of a set of powerful functions for iTV users. To validate our ideas, we introduce an iTV application we developed which incorporates some of these techniques into a simple set of user features, in order to demonstrate the usefulness of content-based techniques for iTV. The contribution of this paper is not to provide an in-depth discussion on each of the individual content-based techniques, but rather to show how many of these powerful technologies can be incorporated into an interactive TV system.\",\n \"Title: Integrating multiple sensor modalities for environmental monitoring of marine locations\\nYear: 2008\\n\\nAbstract: In this paper we present preliminary work on integrating visual sensing with the more traditional sensing modalities for marine locations. We have deployed visual sensing at one of the Smart Coast WSN sites in Ireland and have built a software platform for gathering and synchronizing all sensed data. We describe how the analysis of a range of different sensor modalities can reinforce readings from a given noisy, unreliable sensor.\",\n \"Title: Object-Based access to TV rushes video\\nYear: 2006\\n\\nAbstract: Recent years have seen the development of different modalities for video retrieval. The most common of these are (1) to use text from speech recognition or closed captions, (2) to match keyframes using image retrieval techniques like colour and texture [6] and (3) to use semantic features like “indoor”, “outdoor” or “persons”. Of these, text-based retrieval is the most mature and useful, while image-based retrieval using low-level image features usually depends on matching keyframes rather than whole-shots. Automatic detection of video concepts is receiving much attention and as progress is made in this area we will see consequent impact on the quality of video retrieval. In practice it is the combination of these techniques which realises the most useful, and effective, video retrieval as shown by us repeatedly in TRECVid [5].\",\n \"Title: Semi-automatic semantic enrichment of raw sensor data\\nYear: 2007\\n\\nAbstract: In the XSENSE Project, we gathered a total of 6 biometric sensor data feeds from the participants in our experiments using\\n 3 different sensor devices. These readings were taken during 33 experiments where upto 6 users watched a variety of different\\n films and their reactions were monitored.\",\n \"Title: Improved graph cut segmentation by learning a contrast model on the fly.\\nYear: 2013\\n\\nAbstract: This paper describes an extension to the graph cut interactive image segmentation algorithm based on a novel approach to addressing the well known small cut problem. The approach uses a generative contrast model to weight interaction potentials. The model attempts to capture the expected changes in color between adjacent pixels in the unlabeled area of the image using the adjacent pixels in the user interactions as training data. We compare our approach to the standard graph cuts algorithm and show that the contrast model allows a user to achieve a more accurate segmentation with fewer interactions. We additionally introduce a variant of the approach based on superpixels that further enhances performance but reduces computational complexity to ensure instant feedback for optimal user experience.\",\n \"Title: Smart multi-modal marine monitoring via visual analysis and data fusion\\nYear: 2013\\n\\nAbstract: Estuaries and coastal areas contain increasingly exploited resources that need to be monitored, managed and protected efficiently and effectively. This requires access to reliable and timely data and management decisions must be based on analysis of collected data to avoid or limit negative impacts. Visually supported multi-modal sensing and data fusion offer attractive possibilities for such arduous tasks. In this paper, we demonstrate how an in-situ sensor network can be enhanced with the use of contextual image data. We assimilate and alter a state-of-the-art background modelling technique from the image processing domain in order to detect turbidity spikes in water quality sensor measurements automatically. We then combine this with visual sensing to identify abnormal events that are not caused by local activities. The system can potentially assist those charged with monitoring large scale ecosystems, combining real-time analytics with improved efficiency and effectiveness.\",\n \"Title: Using segmented objects in ostensive video shot retrieval\\nYear: 2005\\n\\nAbstract: This paper presents a system for video shot retrieval in which shots are retrieved based on matching video objects using a combination of colour, shape and texture. Rather than matching on individual objects, our system supports sets of query objects which in total reflect the user's object-based information need. Our work also adapts to a shifting user information need by initiating the partitioning of a user's search into two or more distinct search threads, which can be followed by the user in sequence. This is an automatic process which maps neatly to the ostensive model for information retrieval in that it allows a user to place a virtual checkpoint on their search, explore one thread or aspect of their information need and then return to that checkpoint to then explore an alternative thread. Our system is fully functional and operational and in this paper we illustrate several design decisions we have made in building it.\",\n \"Title: 3DLife - Bringing the Media Internet to Life.\\nYear: 2013\\n\\nAbstract: The 3DLife EU FP7 Network of Excellence focuses on stimulating joint research and integrating leading European research groups to create a long-term integration of critical mass for innovation of currently fragmented research addressing media Internet. It fosters the creation of sustainable and long-term relationships between existing national research groups and lay the foundations for a Virtual Centre of Excellence in 3D media Internet - EMC2. This is a summary of 3DLife’s missions as well as its achievements in the last three years.\",\n \"Title: 3D Estimation and Visualization of Motion in a Multicamera Network for Sports.\\nYear: 2011\\n\\nAbstract: In this work, we develop image processing and computer vision techniques for visually tracking a tennis ball, in 3D, on a court instrumented with multiple low-cost IP cameras. The technique first obtains 2D ball tracking data from each camera view using 2D object tracking methods. Next, an automatic feature-based video synchronization method is applied. This technique uses the extracted 2D ball information from two or more camera views, plus camera calibration information. In order to find 3D trajectory, the temporal 3D locations of the ball is estimated using triangulation of correspondent 2D locations obtained from automatically synchronized videos. Furthermore, in order to improve the continuity of the tracked 3D ball during times when no two cameras have overlapping views of the ball location, we incorporate a physics-based trajectory model into the system. The resultant 3D ball tracks are then visualized in a virtual 3D graphical environment. Finally, we quantify the accuracy of our system in terms of reprojection error.\",\n \"Title: Effects of environmental colour on mood: a wearable LifeColour capture device\\nYear: 2010\\n\\nAbstract: Colour is everywhere in our daily lives and impacts things like our mood, yet we rarely take notice of it. One method of capturing and analysing the predominant colours that we encounter is through visual lifelogging devices such as the SenseCam. However an issue related to these devices is the privacy concerns of capturing image level detail. Therefore in this work we demonstrate a hardware prototype wearable camera that captures only one pixel - of the dominant colour prevelant in front of the user, thus circumnavigating the privacy concerns raised in relation to lifelogging. To simulate whether the capture of dominant colour would be sufficient we report on a simulation carried out on 1.2 million SenseCam images captured by a group of 20 individuals. We compare the dominant colours that different groups of people are exposed to and show that useful inferences can be made from this data. We believe our prototype may be valuable in future experiments to capture colour correlated associated with an individual's mood.\",\n \"Title: Persistent homology for 3d reconstruction evaluation\\nYear: 2012\\n\\nAbstract: Space or voxel carving is a non-invasive technique that is used to produce a 3D volume and can be used in particular for the reconstruction of a 3D human model from images captured from a set of cameras placed around the subject. In [1], the authors present a technique to quantitatively evaluate spatially carved volumetric representations of humans using a synthetic dataset of typical sports motion in a tennis court scenario, with regard to the number of cameras used. In this paper, we compute persistent homology over the sequence of chain complexes obtained from the 3D outcomes with increasing number of cameras. This allows us to analyze the topological evolution of the reconstruction process, something which as far as we are aware has not been investigated to date.\",\n \"Title: Associating characters with events in films\\nYear: 2007\\n\\nAbstract: The work presented here combines the analysis of a film's audiovisual features with the analysis of an accompanying audio description. Specifically, we describe a technique for semantic-based indexing of feature films that associates character names with meaningful events. The technique fuses the results of event detection based on audiovisual features with the inferred on-screen presence of characters, based on an analysis of an audio description script. In an evaluation with 215 events from 11 films, the technique performed the character detection task with Precision = 93% and Recall = 71%. We then go on to show how novel access modes to film content are enabled by our analysis. The specific examples illustrated include video retrieval via a combination of event-type and character name and our first steps towards visualization of narrative and character interplay based on characters occurrence and co-occurrence in events.\",\n \"Title: Considerations for a touchscreen visual lifelog\\nYear: 2011\\n\\nAbstract: In this paper we describe the design considerations for a touchscreen visual lifelog browser. Visual lifelogs are large collections of photographs which represent a person's experiences. Lifelogging devices, such as the wearable camera known as SenseCam, can record thousands of images per day. Utilizing the approach of event segmentation to organize and present these images, we have designed an interface to present lifelog collections for touchscreen interaction, thus increasing accessibility for users.\",\n \"Title: Automatically selecting shots for action movie trailers\\nYear: 2006\\n\\nAbstract: Movie trailers, or previews, are an important method of advertising movies. They are extensively shown before movies in cinemas, as well as on television and increasingly, over the Internet. Making a trailer is a creative process, in which a number of shots from a movie are selected in order to entice a viewer in to paying to see the full movie. Thus, the creation of these trailers is an integral part in the promotion of a movie. Action movies in particular rely on trailers as a form of advertising as it is possible to show short, exciting portions of an action movie, which are likely to appeal to the target audience. This paper presents an approach which automatically selects shots from action movies in order to assist in the creation of trailers. A set of audiovisual features are extracted that aim to model the characteristics of shots typically present in trailers, and a support vector machine is utilised in order to select the relevant shots. The approach taken is not particularly novel but the results show that the process may be used in order to ease the trailer creation process or to facilitate the creation of variable length, or personalised trailers.\",\n \"Title: Pre-Classification For Automatic Image Orientation\\nYear: 2006\\n\\nAbstract: In this paper, we propose a novel method for automatic orientation of digital images. The approach is based on exploiting the properties of local statistics of natural scenes. In this way, we address some of the difficulties encountered in previous works in this area. The main contribution of this paper is to introduce a pre-classification step into carefully defined categories in order to simplify subsequent orientation detection. The proposed algorithm was tested on 9068 images and compared to existing state of the art in the area. Results show a significant improvement over previous works.\",\n \"Title: Balancing the power of multimedia information retrieval and usability in designing interactive tv\\nYear: 2008\\n\\nAbstract: Steady progress in the field of multimedia information retrieval (MMIR) promises a useful set of tools that could provide new usage scenarios and features to enhance the user experience in today's digital media applications. In the interactive TV domain, the simplicity of interaction is more crucial than in any other digital media domain and ultimately determines the success or otherwise of any new applications. Thus when integrating emerging tools like MMIR into interactive TV, the increase in interface complexity and sophistication resulting from these features can easily reduce its actual usability. In this paper we describe a design strategy we developed as a result of our efforts in balancing the power of emerging multimedia information retrieval techniques and maintaining the simplicity of the interface in interactive TV. By providing multiple levels of interface sophistication in increasing order as a viewer repeatedly presses the same button on their remote control, we provide a layered interface that can accommodate viewers requiring varying degrees of power and simplicity. A series of screen shots from the system we have actually developed and built illustrates how this is achieved.\",\n \"Title: Tennissense: A Multi-Modal Sensing Platform For Sport\\nYear: 2009\\n\\nAbstract: The evolution of the World-Wide Web to the Sensor Web is providing an unprecedented opportunity to develop novel applications in a variety of domains. In this article we describe our work on multi-modal sensing for sport.\",\n \"Title: A user-centered approach to rushes summarisation via highlight-detected keyframes\\nYear: 2007\\n\\nAbstract: We present our keyframe-based summary approach for BBC Rushes video as part of the TRECVid Summarisation benchmark evaluation carried out in 2007. We outline our approach to summarisation that uses video processing for feature extraction and is informed by human factors considerations for summary presentation. Based on the performance of our generated summaries as reported by NIST, we subsequently undertook detailed failure analysis of our approach. The findings of this investigation as well as recommendations for alterations to our keyframe-based summary generation method, and the evaluation methodology for Rushes summaries in general, are detailed within this paper.\",\n \"Title: User-Feedback on a Feature-Rich Photo Organiser\\nYear: 2008\\n\\nAbstract: As the proliferation of digital photography increases, the software used to manage our increasingly large collections of digital photos becomes ever more important. In this paper we present the findings of a study which investigates how people view and interact with a set of photo management features. Specifically, a group of users are set the task of managing their own photos using a system built to encompass a wide range of photo organization functionality. They are then quizzed about their experiences in terms of their feature preferences, the general usability of the system, and other suggestions/requirements. Given these opinions, a basic estimation is then formed on what they like/dislike about the various aspects of the system, towards obtaining a more learned understanding of how we may develop a photo organizer that is optimal in terms of user satisfaction.\",\n \"Title: Online Television Library: Organisation And Content Browsing For General Users\\nYear: 2001\\n\\nAbstract: This paper describes the organisational and playback features of Fischlar, a digital video library that allows users to record, browse and watch television programmes online. Programmes that can be watched acid recorded are organised by personal recommendations, genre classifications, name and other attributes for access by general television users. Motivations and interactions of users with online television libraries are outlined and they are also supported by personalised library access, categorised programmes, a combined player browser with content viewing history and content marks. The combined player browser supports a user who watches a programme on different occasions in a non-sequential order.\",\n \"Title: Enhanced visualisation of dance performance from automatically synchronised multimodal recordings\\nYear: 2011\\n\\nAbstract: The Huawei/3DLife Grand Challenge Dataset provides multimodal recordings of Salsa dancing, consisting of audiovisual streams along with depth maps and inertial measurements. In this paper, we propose a system for augmented reality-based evaluations of Salsa dancer performances. An essential step for such a system is the automatic temporal synchronisation of the multiple modalities captured from different sensors, for which we propose efficient solutions. Furthermore, we contribute modules for the automatic analysis of dance performances and present an original software application, specifically designed for the evaluation scenario considered, which enables an enhanced dance visualisation experience, through the augmentation of the original media with the results of our automatic analyses.\",\n \"Title: An Evaluation of Local Action Descriptors for Human Action Classification in the Presence of Occlusion\\nYear: 2014\\n\\nAbstract: This paper examines the impact that the choice of local descriptor has on human action classifier performance in the presence of static occlusion. This question is important when applying human action classification to surveillance video that is noisy, crowded, complex and incomplete. In real-world scenarios, it is natural that a human can be occluded by an object while carrying out different actions. However, it is unclear how the performance of the proposed action descriptors are affected by the associated loss of information. In this paper, we evaluate and compare the classification performance of the state-of-art human local action descriptors in the presence of varying degrees of static occlusion. We consider four different local action descriptors: Trajectory (TRAJ), Histogram of Orientation Gradient (HOG), Histogram of Orientation Flow (HOF) and Motion Boundary Histogram (MBH). These descriptors are combined with a standard bag-of-features representation and a Support Vector Machine classifier for action recognition. We investigate the performance of these descriptors and their possible combinations with respect to varying amounts of artificial occlusion in the KTH action dataset. This preliminary investigation shows that MBH in combination with TRAJ has the best performance in the case of partial occlusion while TRAJ in combination with MBH achieves the best results in the presence of heavy occlusion.\",\n \"Title: Identifying Different Settings in a Visual Diary\\nYear: 2008\\n\\nAbstract: We describe an approach to identifying specific settings in large collections of photographs corresponding to a visual diary. An algorithm developed for setting detection should be capable of clustering images captured at the same real world locations (e.g. in the dining room at home, in front of the computer in the office, in the park, etc.). This requires the selection and implementation of suitable methods to identify visually similar backgrounds in images using their visual features. The goal of the work reported here is to automatically detect settings in images taken over a single week. We achieve this using Scale Invariant Feature Transform (SIFT) features and X-means clustering. In addition, we also explore how the use of location based metadata can aid this process.\",\n \"Title: Motion Synthesis for Sports Using Unobtrusive Lightweight Body-Worn and Environment Sensing.\\nYear: 2013\\n\\nAbstract: The ability to accurately achieve performance capture of athlete motion during competitive play in near real-time promises to revolutionize not only broadcast sports graphics visualization and commentary, but also potentially performance analysis, sports medicine, fantasy sports and wagering. In this paper, we present a highly portable, non-intrusive approach for synthesizing human athlete motion in competitive game-play with lightweight instrumentation of both the athlete and field of play. Our data-driven puppetry technique relies on a pre-captured database of short segments of motion capture data to construct a motion graph augmented with interpolated motions and speed variations. An athlete's performed motion is synthesized by finding a related action sequence through the motion graph using a sparse set of measurements from the performance, acquired from both worn inertial and global location sensors. We demonstrate the efficacy of our approach in a challenging application scenario, with a high-performance tennis athlete wearing one or more lightweight body-worn accelerometers and a single overhead camera providing the athlete's global position and orientation data. However, the approach is flexible in both the number and variety of input sensor data used. The technique can also be adopted for searching a motion graph efficiently in linear time in alternative applications.\",\n \"Title: Sensor node localisation using a stereo camera rig\\nYear: 2007\\n\\nAbstract: In this paper, we use stereo vision processing techniques to detect and localise sensors used for monitoring simulated environmental events within an experimental sensor network testbed. Our sensor nodes communicate to the camera through patterns emitted by light emitting diodes (LEDs). Ultimately, we envisage the use of very low-cost, low-power, compact microcontroller-based sensing nodes that employ LED communication rather than power hungry RF to transmit data that is gathered via existing CCTV infrastructure. To facilitate our research, we have constructed a controlled environment where nodes and cameras can be deployed and potentially hazardous chemical or physical plumes can be introduced to simulate environmental pollution events in a controlled manner. In this paper we show how 3D spatial localisation of sensors becomes a straightforward task when a stereo camera rig is used rather than a more usual 2D CCTV camera.\",\n \"Title: A system for event-based film browsing\\nYear: 2006\\n\\nAbstract: The recent past has seen a proliferation in the amount of digital video content being created and consumed. This is perhaps being driven by the increase in audiovisual quality, as well as the ease with which production, reproduction and consumption is now possible. The widespread use of digital video, as opposed its analogue counterpart, has opened up a plethora of previously impossible applications. This paper builds upon previous work that analysed digital video, namely movies, in order to facilitate presentation in an easily navigable manner. A film browsing interface, termed the MovieBrowser, is described, which allows users to easily locate specific portions of movies, as well as to obtain an understanding of the filming being perused. A number of experiments which assess the system's performance are also presented.\",\n \"Title: Security Considerations and Key Negotiation Techniques for Power Constrained Sensor Networks\\nYear: 2006\\n\\nAbstract: Sensor networks are becoming increasingly important for a wide variety of applications including environmental monitoring, building safety and emergency relief services. A typical sensor network consists of a large number of small, low-power, low-cost nodes that form a self-organized network using wireless peer-to-peer communication. Because sensor networks pose unique constraints on their operation, traditional security techniques used by conventional networks cannot be applied. In this paper we consider the operational issues and security threats to sensor networks. We discuss the state of the art in terms of sensor network security and we examine the practicality of using efficient elliptic curve algorithms and identity based encryption to deploy a secure sensor network infrastructure. We evaluate the potential for realizing this on low-power, long-life devices by measuring power consumption of the operations needed for key management in a sensor network and thus provide further evidencefor the feasibility of the approach.\",\n \"Title: Audio-Visual Classification Video Browser\\nYear: 2014\\n\\nAbstract: This paper presents our third participation in the Video Browser Showdown. Building on the experience that we gained while participating in this event, we compete in the 2014 showdown with a more advanced browsing system based on incorporating several audio-visual retrieval techniques. This paper provides a short overview of the features and functionality of our new system.\",\n \"Title: User evaluation of Físchlár-News: An automatic broadcast news delivery system\\nYear: 2006\\n\\nAbstract: Technological developments in content-based analysis of digital video information are undergoing much progress, with ideas for fully automatic systems now being proposed and demonstrated. Yet because we do not yet have robust operational video retrieval systems that can be deployed and used, the usual HCI practise of conducting a usage study and an informed iterative system design is thus not possible. Físchlár-News is one of the first automatic, content-based broadcast news analysis and archival systems that process broadcast news video so that users can search, browse, and play it in an easy-to-use manner with a conventional web browser. The system incorporates a number of state-of-the-art research components, some of which are not yet considered mature technology, yet it has been built to be robust enough to be deployed to users who are interested in access to daily news throughout a university campus. In this article we report and discuss a user-evaluation study conducted with 16 users, each of whom utilized the system freely for a one month period. Results from a detailed qualitative analysis are presented, looking at collected questionnaires, incident diaries, and interaction-log data. The findings suggest that our users employed the system in conjunction with their other news update methods, such as watching TV news at home and browsing online news websites at their workplace, their major concerns being up-to-dateness and coverage of the news content. They tried to accommodate the system to fit their established web browsing habits, and they found local news content and the ability to play self-contained news stories on their desktop as major values of the system. Our study also resulted in a detailed wishlist of new features which will help in the further development of both our and others' systems.\",\n \"Title: A virtual coaching environment for improving golf swing technique\\nYear: 2010\\n\\nAbstract: As a proficient golf swing is a key element of success in golf, many golfers make significant effort improving their stroke mechanics. In order to help enhance golfing performance, it is important to identify the performance determining factors within the full golf swing. In addition, explicit instructions on specific features in stroke technique requiring alterations must be imparted to the player in an unambiguous and intuitive manner. However, these two objectives are difficult to achieve due to the subjective nature of traditional coaching techniques and the predominantly implicit knowledge players have of their movements. In this work, we have developed a set of visualisation and analysis tools for use in a virtual golf coaching environment. In this virtual coaching studio, the analysis tools allow for specific areas require improvement in a player's 3D stroke dynamics to be isolated. An interactive 3D virtual coaching environment then allows detailed and unambiguous coaching information to be visually imparted back to the player via the use of two virtual human avatars; the first mimics the movements performed by the player; the second takes the role of a virtual coach, performing ideal stroke movement dynamics. The potential of the coaching tool is highlighted in its use by sports science researchers in the evaluation of competing approaches for calculating the X-Factor, a significant performance determining factor for hitting distance in a golf swing.\",\n \"Title: The colour of life: novel visualisations of population lifestyles\\nYear: 2010\\n\\nAbstract: Colour permeates our daily lives, yet we rarely take notice of it. In this work we utilise the SenseCam (a visual lifelogging tool), to investigate the predominant colours in one million minutes of human life that a group of 20 individuals encounter throughout their normal daily activities. We also compare the colours that different groups of people are exposed to in their typical days. This information is presented in using a novel colour-wheel visualisation which is a new means of illustrating that people are exposed to bright colours over longer durations of time during summer months, and more dark colours during winter months.\",\n \"Title: InSPeCT: integrated surveillance for port container traffic\\nYear: 2011\\n\\nAbstract: This paper describes a fully-operational content-indexing and management system, designed for monitoring and profiling freight-based vehicular traffic in a seaport environment. The 'InSPeCT' system captures video footage of passing vehicles and uses tailored OCR to index the footage according to vehicle license plates and freight codes. In addition to real-time functionality such as alerting, the system provides advanced search techniques for the efficient retrieval of records, where each vehicle is profiled according to multi-angled video, context information, and links to external information sources. Currently being piloted at a busy national seaport, the feedback from port officials indicates the system to be extremely useful in supplementing their existing transportation-security structures.\",\n \"Title: Local Wavelet Features for Statistical Object Classification and Localization\\nYear: 2010\\n\\nAbstract: This article presents a system for texture-based probabilistic classification and localization of 3D objects in 2D digital images and discusses selected applications.\",\n \"Title: Event detection in pedestrian detection and tracking applications\\nYear: 2007\\n\\nAbstract: In this paper, we present a system framework for event detection in pedestrian and tracking applications. The system is built upon a robust computer vision approach to detecting and tracking pedestrians in unconstrained crowded scenes. Upon this framework we propose a pedestrian indexing scheme and suite of tools for detecting events or retrieving data from a given scenario.\",\n \"Title: Breathing Feedback System with Wearable Textile Sensors\\nYear: 2010\\n\\nAbstract: Breathing exercises form an essential part of the treatment for respiratory illnesses such as cystic fibrosis. Ideally these exercises should be performed on a daily basis. This paper presents an interactive system using a wearable textile sensor to monitor breathing patterns. A graphical user interface provides visual real-time feedback to patients. The aim of the system is to encourage the correct performance of prescribed breathing exercises by monitoring the rate and the depth of breathing. The system is straight forward to use, low-cost and can be installed easily within a clinical setting or in the home. Monitoring the user with a wearable sensor gives real-time feedback to the user as they perform the exercise, allowing them to perform the exercises independently. There is also potential for remote monitoring where the user’s overall performance over time can be assessed by a clinician.\",\n \"Title: Vision-Based Analysis Of Pedestrian Traffic Data\\nYear: 2008\\n\\nAbstract: Reducing traffic congestion has become a major issue within urban environments. Traditional approaches, such as increasing road sizes, may prove impossible in certain scenarios, such as city centres, or ineffectual if current predictions of large growth in world traffic volumes hold true. An alternative approach lies with increasing the management efficiency of pre-existing infrastructure and public transport systems through the use of Intelligent Transportation Systems (ITS). In this paper, we focus on the requirement of obtaining robust pedestrian traffic flow data within these areas. We propose the use of a flexible and robust stereo-vision pedestrian detection and tracking approach as a basis for obtaining this information. Given this framework, we propose the use of a pedestrian indexing scheme and a suite of tools, which facilitates the declaration of user-defined pedestrian events or requests for specific statistical traffic: flow data. The detection of the required events or the constant flow of statistical information can be incorporated into a variety of ITS solutions for applications in traffic management, public transport systems and urban planning.\",\n \"Title: Interactive experiments in object-based retrieval\\nYear: 2006\\n\\nAbstract: Object-based retrieval is a modality for video retrieval based on segmenting objects from video and allowing end-users to use these objects as part of querying. In this paper we describe an empirical TRECVid-like evaluation of object-based search, and compare it with a standard image-based search into an interactive experiment with 24 search topics and 16 users each performing 12 search tasks on 50 hours of rushes video. This experiment attempts to measure the impact of object-based search on a corpus of video where textual annotation is not available.\",\n \"Title: Low Complexity Video Compression Using Moving Edge Detection Based on DCT Coefficients\\nYear: 2009\\n\\nAbstract: In this paper, we propose a new low complexity video compression method based on detecting blocks containing moving edges using only DCT coefficients. The detection, whilst being very efficient, also allows efficient motion estimation by constraining the search process to moving macro-blocks only. The encoders PSNR is degraded by 2dB compared to H.264/AVC inter for such scenarios, whilst requiring only 5% of the execution time. The computational complexity of our approach is comparable to that of the DISCOVER codec which is the state of the art low complexity distributed video coding. The proposed method finds blocks with moving edge blocks and processes only selected blocks. The approach is particularly suited to surveillance type scenarios with a static camera.\",\n \"Title: An interactive and multi-level framework for summarising user generated videos\\nYear: 2009\\n\\nAbstract: We present an interactive and multi-level abstraction framework for user-generated video (UGV) summarisation, allowing a user the flexibility to select a summarisation criterion out of a number of methods provided by the system. First, a given raw video is segmented into shots, and each shot is further decomposed into sub-shots in line with the change in dominant camera motion. Secondly, principal component analysis (PCA) is applied to the colour representation of the collection of sub-shots, and a content map is created using the first few components. Each sub-shot is represented with a \\\"footprint\\\" on the content map, which reveals its content significance (coverage) and the most dynamic segment. The final stage of abstraction is devised in a user-assisted manner whereby a user is able to specify a desired summary length, with options to interactively perform abstraction at different granularity of visual comprehension. The results obtained show the potential benefit in significantly alleviating the burden of laborious user intervention associated with conventional video editing/browsing.\",\n \"Title: Complexity adaptation in H.264/AVC video coder for static cameras.\\nYear: 2009\\n\\nAbstract: H.264/AVC uses variable block size motion estimation (VBSME) to improve coding gain. However, its complexity is significant and fixed regardless of the required quality or of the scene characteristics. In this paper, we propose an adaptive complexity algorithm based on using the Walsh Hadamard Transform (WHT). VBS automatic partition and skip mode detection algorithms also are proposed. Experimental results show that 70% - 5% of the computation of H.264/AVC is required to achieve the same PSNR.\",\n \"Title: Semantic Analysis of Field Sports Video using a Petri-Net of Audio-Visual Concepts\\nYear: 2009\\n\\nAbstract: The most common approach to automatic summarization and highlight detection in sports video is to train an automatic classifier to detect semantic highlights based on occurrences of low-level features such as action replays, excited commentators or changes in a scoreboard. We propose an alternative approach based on the detection of perception concepts (PCs) and the construction of Petri-Nets, which can be used for both semantic description and event detection within sports videos. Low-level algorithms to detect PCs using visual, aural and motion characteristics are proposed, and a series of Petri-Nets composed of PCs is formally defined to describe video content. We call this a perception concept network–Petri-Net (PCN–PN) model. Using PCN–PNs, personalized high-level semantic descriptions of video highlights can be facilitated and queries on high-level semantics can be achieved. A particular strength of this framework is that we can easily build semantic detectors based on PCN–PNs to search within sports videos and locate interesting events. Experimental results based on recorded sports video data across three types of sports games (soccer, basketball and rugby), and each from multiple broadcasters, are used to illustrate the potential of this framework.\",\n \"Title: Blending real with virtual in 3DLife\\nYear: 2013\\n\\nAbstract: Part of 3DLife's major goal to bring the 3D media Internet to life, concerns the development and wide-spread distribution of online tele-immersive (TI) virtual environments. As the techniques powering challenging tasks for user reconstruction and activity tracking within a virtual environment are maturing, along with consumer-grade availability of specialized hardware, this paper focuses on the simple practices used to make real-time tele-immersion within a networked virtual world a reality.\",\n \"Title: Low-cost creation of a 3D interactive museum exhibition\\nYear: 2011\\n\\nAbstract: We present a demonstration of a multi-sensory virtual experience that accurately reflects the experience of a real visit to a museum. We have developed a 3D interactive digital museum exhibition corresponding to a photo-realistic 3D reconstruction of the Iconic Treasures exhibition at the National Museum of Ireland's archaeology building. Users can explore the 3D virtual environment and interact with the displays by accessing high resolution photographs and historical descriptions of the artefacts. This demo will showcase the experience on a 3D laptop with the use of active shutter LCD glasses to create an immersive experience. A key aspect of the demonstration is that it was developed using low-cost or freely available OTS tools wherever possible putting the creation of such digital exhibitions within reach of even modest budgets.\",\n \"Title: An Investigation into Feature Effectiveness for Multimedia Hyperlinking\\nYear: 2014\\n\\nAbstract: The increasing amount of archival multimedia content available online is creating increasing opportunities for users who are interested in exploratory search behaviour such as browsing. The user experience with online collections could therefore be improved by enabling navigation and recommendation within multimedia archives, which can be supported by allowing a user to follow a set of hyperlinks created within or across documents. The main goal of this study is to compare the performance of different multimedia features for automatic hyperlink generation. In our work we construct multimedia hyperlinks by indexing and searching textual and visual features extracted from the blip.tv dataset. A user-driven evaluation strategy is then proposed by applying the Amazon Mechanical Turk (AMT) crowdsourcing platform, since we believe that AMT workers represent a good example of \\\\\\\"real world\\\\\\\" users. We conclude that textual features exhibit better performance than visual features for multimedia hyperlink construction. In general, a combination of ASR transcripts and metadata provides the best results.\",\n \"Title: The AXES PRO video search system\\nYear: 2013\\n\\nAbstract: We demonstrate a multimedia content information retrieval engine developed for audiovisual digital libraries targeted at media professionals. It is the first of three multimedia IR systems being developed by the AXES project. The system brings together traditional text IR and state-of-the-art content indexing and retrieval technologies to allow users to search and browse digital libraries in novel ways. Key features include: metadata and ASR search and filtering, on-the-fly visual concept classification (categories, faces, places, and logos), and similarity search (instances and faces).\",\n \"Title: Towards Automated Robust Vision-Based Surveillance\\nYear: 2008\\n\\nAbstract: COST is one of the longest‐running instruments funded by the EU RTD Framework Program. The members of the COST 292 action (see: http://www.cost292.org/) have a long tradition of involvement in WIAMIS, dating back to the establishment of this event. Since 2005, the action has been invited to organize a special session and this tradition was continued for WIAMIS 2008. This year, the special session focused on a subset of the broad research remit of the action. Specifically, the session targets research in the field of automated visual surveillance. This focus reflects a growing interest within COST 292 participants in this increasingly important area. The goal of this special session is to help bring together researchers working on this topic, both within COST 292 and beyond, with a view to stimulating future collaborative research in this area. The widely circulated call for papers targeted submissions on a broad range of topics covered by the above mentioned focus, including visual computation, event and activity modelingand analysis, multiple stream analysis, architectures, indexing and storage, coding and applications. All papers were peer reviewed by at least three reviewers drawn from a combination of the WIAMIS Technical Program Committee and a special Program Subcommittee set up specifically for this special session. Acceptance criteria considered overall quality as well as relevance to the topics of the special session. In the end, just 5 papers were accepted for oral presentation. The accepted papers address scene modeling, event detection, object recognition (human and non‐human) and fusion of multiple complementary data sources.\",\n \"Title: Measuring the impact of temporal context on video retrieval\\nYear: 2008\\n\\nAbstract: In this paper we describe the findings from the K-Space interactive video search experiments in TRECVid 2007, which examined the effects of including temporal context in video retrieval. The traditional approach to presenting video search results is to maximise recall by offering a user as many potentially relevant shots as possible within a limited amount of time. 'Context'-oriented systems opt to allocate a portion of the results presentation space to providing additional contextual cues about the returned results. In video retrieval these cues often include temporal information such as a shot's location within the overall video broadcast and/or its neighbouring shots. We developed two interfaces with identical retrieval functionality in order to measure the effects of such context on user performance. The first system had a 'recall-oriented' interface, where results from a query were presented as a ranked list of shots. The second was 'context-oriented', with results presented as a ranked list of broadcasts. 10 users participated in the experiments, of which 8 were novices and 2 experts. Participants completed a number of retrieval topics using both the recall-oriented and context-oriented systems.\",\n \"Title: Toward automated evaluation of interactive segmentation\\nYear: 2011\\n\\nAbstract: We previously described a system for evaluating interactive segmentation by means of user experiments (McGuinness and O'Connor, 2010) [1]. This method, while effective, is time-consuming and labor-intensive. This paper aims to make evaluation more practicable by investigating if it is feasible to automate user interactions. To this end, we propose a general algorithm for driving the segmentation that uses the ground truth and current segmentation error to automatically simulate user interactions. We investigate four strategies for selecting which pixels will form the next interaction. The first of these is a simple, deterministic strategy; the remaining three strategies are probabilistic, and focus on more realistically approximating a real user. We evaluate four interactive segmentation algorithms using these strategies, and compare the results with our previous user experiment-based evaluation. The results show that automated evaluation is both feasible and useful.\",\n \"Title: MyPlaces: detecting important settings in a visual diary\\nYear: 2008\\n\\nAbstract: We describe a novel approach to identifying specific settings in large collections of passively captured images corresponding to a visual diary. An algorithm developed for setting detection should be capable of detecting images captured at the same real world locations (e.g. in the dining room at home, in front of the computer in the office, in the park, etc.). This requires the selection and implementation of suitable methods to identify visually similar backgrounds in images using their visual features. We use a Bag of Keypoints approach. This method is based on the sampling and subsequent vector quantization of multiple image patches. The image patches are sampled and described using Scale Invariant Feature Transform (SIFT) features. We compare three different classifiers, K Nearest Neighbour (KNN), Multiclass Linear Perceptron (MLP), and Support Vector Machine (SVM), and present results for classifying ten different settings across one week's worth of images. Our results demonstrate that the method produces good classification accuracy even without exploiting geometric or context based information. We also describe an early prototype of a visual diary browser that integrates the classification results.\",\n \"Title: Investigation of Image Models for Landmark Classification.\\nYear: 2009\\n\\nAbstract: One commonly used approach to scene localization and landmark recognition is to match an input image against a large annotated database of images using local image features. However problems exist with these approaches relating to memory constraints and the processing time required to compare high dimensional image feature vectors in a very large scale database.\\\\par We investigate a new landmark classification technique which takes advantage of the fact that there is considerable overlap in visually similar images of landmarks in any large public photo repository. A large number of images containing landmarks are clustered into visually similar clusters. Classification models are then implemented and trained based on global histograms of interest point features from these clusters to create models which can be used for robust real-time accurate classification of images containing these landmarks. We also investigate different techniques for the creation of these classification models to ascertain how best to guarantee a high level of robustness, accuracy and speed.\",\n \"Title: Robust pedestrian detection and tracking in crowded scenes\\nYear: 2009\\n\\nAbstract: In this paper, a robust computer vision approach to detecting and tracking pedestrians in unconstrained crowded scenes is presented. Pedestrian detection is performed via a 3D clustering process within a region-growing framework. The clustering process avoids using hard thresholds by using bio-metrically inspired constraints and a number of plan-view statistics. Pedestrian tracking is achieved by formulating the track matching process as a weighted bipartite graph and using a Weighted Maximum Cardinality Matching scheme. The approach is evaluated using both indoor and outdoor sequences, captured using a variety of different camera placements and orientations, that feature significant challenges in terms of the number of pedestrians present, their interactions and scene lighting conditions. The evaluation is performed against a manually generated groundtruth for all sequences. Results point to the extremely accurate performance of the proposed approach in all cases.\",\n \"Title: Kinect vs. Low-cost Inertial Sensing for Gesture Recognition\\nYear: 2014\\n\\nAbstract: In this paper, we investigate efficient recognition of human gestures / movements from multimedia and multimodal data, including the Microsoft Kinect and translational and rotational acceleration and velocity from wearable inertial sensors. We firstly present a system that automatically classifies a large range of activities (17 different gestures) using a random forest decision tree. Our system can achieve near real time recognition by appropriately selecting the sensors that led to the greatest contributing factor for a particular task. Features extracted from multimodal sensor data were used to train and evaluate a customized classifier. This novel technique is capable of successfully classifying various gestures with up to 91 % overall accuracy on a publicly available data set. Secondly we investigate a wide range of different motion capture modalities and compare their results in terms of gesture recognition accuracy using our proposed approach. We conclude that gesture recognition can be effectively performed by considering an approach that overcomes many of the limitations associated with the Kinect and potentially paves the way for low-cost gesture recognition in unconstrained environments.\",\n \"Title: Stopping region-based image segmentation at meaningful partitions\\nYear: 2007\\n\\nAbstract: This paper proposes a new stopping criterion for automatic image segmentation based on region merging. The criterion is dependent on image content itself and when combined with the recently proposed approaches to syntactic segmentation can produce results aligned with the most salient semantic regions/objects present in the scene across heterogeneous image collections. The method identifies a single iteration from the merging process as the stopping point, based on the evolution of an accumulated merging cost during the complete merging process. The approach is compared to three commonly used stopping criteria: (i) required number of regions, (ii) value of the least link cost, and (iii) Peak Signal to Noise Ratio (PSNR). For comparison, the stopping criterion is also evaluated for a segmentation approach that does not use syntactic extensions. All experiments use a manually generated segmentation ground truth and spatial accuracy measures. Results show that the proposed stopping criterion improves segmentation performance towards reflecting real-world scene content when integrated into a syntactic segmentation framework.\",\n \"Title: Automatic TV Advertisement Detection from MPEG Bitstream\\nYear: 2001\\n\\nAbstract: The Centre for Digital Video Processing at Dublin City University conducts concentrated research and development in the area of digital video management. The current stage of development is demonstrated on our Web-based digital video system called Fı́schlár (Proceedings of the Content based Multimedia Information Access, RIAO 2000, Vol. 2, Paris, France, 12–14 April 2000, p. 1390), which provides for efficient recording, analysing, browsing and viewing of digitally captured television programmes. Advertisement breaks during or between television programmes are typically recognised by a series of ‘black’ video frames simultaneously accompanying a depression in audio volume which separate each advertisement from one another by recurrently occurring before and after each individual advertisement. It is the regular prevalence of these flags that enables automatic differentiation between what is programme and what is a commercial break. This paper reports on the progress made in the development of this idea into an advertisement detector system that automatically detects the commercial breaks from the bitstream of digitally captured television broadcasts.\",\n \"Title: Keyframe detection in visual lifelogs\\nYear: 2008\\n\\nAbstract: The SenseCam is a wearable camera that passively captures images. Therefore, it requires no conscious effort by a user in taking a photo. A Visual Diary from such a source could prove to be a valuable tool in assisting the elderly, individuals with neurodegenerative diseases, or other traumas. One issue with Visual Lifelogs is the large volume of image data generated. In previous work, we segmented a day's worth of images into more manageable segments, i.e. into distinct events or activities. However, each event could still consist of 80-100 images, thus, in this paper we propose a novel approach to selecting the key images within an event using a combination of MPEG-7 and Scale Invariant Feature Transform (SIFT) features.\",\n \"Title: Tools for User Interaction in Immersive Environments\\nYear: 2014\\n\\nAbstract: REVERIE REal and Virtual Engagement in Realistic Immersive Environments is a large scale collaborative project co-funded by the European Commission targeting novel research in the general domain of Networked Media and Search Systems. The project aims to bring about a revolution in 3D media and virtual reality by developing technologies for safe, collaborative, online environments that can enable realistic interpersonal communication and interaction in immersive environments. To date, project partners have been developing component technologies for a variety of functionalities related to the aims of REVERIE prior to integration into an end-to-end system. In this demo submission, we first introduce the project in general terms, outlining the high-level concept and vision before briefly describing the suite of demonstrations that we intend to present at MMM 2014.\",\n \"Title: Mo Músaem Fíorúil: A Web-Based Search and Information Service for Museum Visitors\\nYear: 2008\\n\\nAbstract: We describe the prototype of an interactive, web-based, museum artifact search and information service. Mo Músaem Fíorúil clusters and indexes images of museum artifacts taken by visitors to the museum where the images are captured using a passive capture device such as Microsoft's SenseCam [1]. The system also matches clustered artifacts to images of the same artifact from the museums official photo collection and allows the user to view images of the same artifact taken by other visitors to the museum. This matching process potentially allows the system to provide more detailed information about a particular artifact to the user based on their inferred preferences, thereby greatly enhancing the user's overall museum experience. In this work, we introduce the system and describe, in broad terms, it's overall functionality and use. Using different image sets of artificial museum objects, we also describe experiments and results carried out in relation to the artifact matching component of the system.\",\n \"Title: Towards Fully Automatic Image Segmentation Evaluation\\nYear: 2008\\n\\nAbstract: Spatial region (image) segmentation is a fundamental step for many computer vision applications. Although many methods have been proposed, less work has been done in developing suitable evaluation methodologies for comparing different approaches. The main problem of general purpose segmentation evaluation is the dilemma between objectivity and generality. Recently, figure ground segmentation evaluation has been proposed to solve this problem by defining an unambiguous ground truth using the most salient foreground object. Although the annotation of a single foreground object is less complex than the annotation of all regions within an image, it is still quite time consuming, especially for videos. A novel framework incorporating background subtraction for automatic ground truth generation and different foreground evaluation measures is proposed, that allows to effectively and efficiently evaluate the performance of image segmentation approaches. The experiments show that the objective measures are comparable to the subjective assessment and that there is only a slight difference between manually annotated and automatically generated ground truth.\",\n \"Title: Pedestrian detection in uncontrolled environments using stereo and biometric information\\nYear: 2006\\n\\nAbstract: A method for pedestrian detection from challenging real world outdoor scenes is presented in this paper. This technique is able to extract multiple pedestrians, of varying orientations and appearances, from a scene even when faced with large and multiple occlusions. The technique is also robust to changing background lighting conditions and effects, such as shadows. The technique applies an enhanced method from which reliable disparity information can be obtained even from untextured homogeneous areas within a scene. This is used in conjunction with ground plane estimation and biometric information,to obtain reliable pedestrian regions. These regions are robust to erroneous areas of disparity data and also to severe pedestrian occlusion, which often occurs in unconstrained scenarios.\",\n \"Title: Indexing of Fictional Video Content for Event Detection and Summarisation.\\nYear: 2007\\n\\nAbstract: This paper presents an approach to movie video indexing that utilises audiovisual analysis to detect important and meaningful temporal video segments, that we term events. We consider three event classes, corresponding to dialogues, action sequences, and montages, where the latter also includes musical sequences. These three event classes are intuitive for a viewer to understand and recognise whilst accounting for over 90% of the content of most movies. To detect events we leverage traditional filmmaking principles and map these to a set of computable low-level audiovisual features. Finite state machines (FSMs) are used to detect when temporal sequences of specific features occur. A set of heuristics, again inspired by filmmaking conventions, are then applied to the output of multiple FSMs to detect the required events. A movie search system, named MovieBrowser, built upon this approach is also described. The overall approach is evaluated against a ground truth of over twenty-three hours of movie content drawn from various genres and consistently obtains high precision and recall for all event classes. A user experiment designed to evaluate the usefulness of an event-based structure for both searching and browsing movie archives is also described and the results indicate the usefulness of the proposed approach.\",\n \"Title: Experiencing SenseCam: a case study interview exploring seven years living with a wearable camera\\nYear: 2013\\n\\nAbstract: This paper presents the findings from an interview with CG, an individual who has worn an automated camera, the SenseCam, every day for the past seven years. Of interest to the study were the participant's day-to-day experiences wearing the camera and whether these had changed since first wearing the camera. The findings presented outline the effect that wearing the camera has on his self-identity, relationships and interactions with people in the public. Issues relating to data capture, transfer and retrieval of lifelog images are also identified. These experiences inform us of the long-term effects of digital life capture and how lifelogging could progress in the future.\",\n \"Title: A Sensing Platform for Physiological and Contextual Feedback to Tennis Athletes\\nYear: 2009\\n\\nAbstract: In this paper we describe our work on creating a multimodal sensing platform for providing feedback to tennis coaches and players. The platform includes a fixed installation around a tennis court consisting of a video camera network and a localisation system as well as wearable sensing technology deployed to individual athletes. We describe the various components of this platform and explain how we can capture synchronised multi-modal sensor data streams for games or training sessions. We then describe the content-based retrieval system we are building to facilitate the development of novel coaching tools. We provide some examples of the queries that the system can support, where these queries are chosen to be suitably expressive so as to reflect a coach’s complex information needs regarding tennis-related performance factors.\",\n \"Title: Using text search for personal photo collections with the MediAssist system\\nYear: 2007\\n\\nAbstract: The MediAssist system enables organisation and searching of personal digital photo collections based on contextual information, content-based analysis and semi-automatic annotation. One mode of user interaction uses automatically extracted features to create text surrogates for photos, which enables text search of photo collections without manual annotation. Our evaluation shows that this text search facility is effective for known-item search.\",\n \"Title: SCReen adjusted panoramic effect: SCRAPE\\nYear: 2013\\n\\nAbstract: A Cave Automatic Virtual Environment (CAVE) is an enclosed virtual reality room that uses multiple projectors to display images across its surfaces. It uses one or more computers to synchronise and combine the images and allows users to control virtual worlds using a host of interaction devices. Traditionally, a CAVE is used by a single user at any one time and by utilising some form of motion sensing, the user's head position can be tracked to allow for first virtual perception. The images are then displayed in stereographic 3D in order to complete the virtual reality effect. Professional CAVE installations are expensive and can cost upwards of several hundred thousand euros. This tends to act as a significant barrier to their propagation, however, as the reduction in cost of high specification computers, projectors and graphics cards continues apace, it has sparked a renewed interest in CAVE environments and given rise to the realistic possibility of setting up low cost, amateur CAVEs. Unfortunately, one of the greatest disadvantages of CAVE systems is the lack of inexpensive, easy to use, specialised software. In this paper we present an open source and easy to use CAVE software toolkit called SCReen Adjusted Panoramic Effect or SCRAPE for short. We believe that SCRAPE is the first major piece in a longer-term vision that aims to bring easy to setup, easy to use, portable CAVE systems to all types of non-expert users.\",\n \"Title: Unsupervised Feature Selection for Detection Using Mutual Information Thresholding\\nYear: 2008\\n\\nAbstract: This paper proposes a method for unsupervised selection of features for detecting important events in a surveillance context. While traditional feature selection requires manually annotated ground truth to choose the best features, we examine the possibility of exploiting the redundancy between a pair of independent data sources for selecting good detection features. Building on our prior work on mutual information thresholding, we show that strong agreement between data sources indicates strong detection performance. Experimental tests, combining visual and audio data, show that the best performing features can be automatically selected by taking advantage of the common information shared by the sensors.\",\n \"Title: Combining image descriptors to effectively retrieve events from visual lifelogs\\nYear: 2008\\n\\nAbstract: The SenseCam is a wearable camera that passively captures approximately 3,000 images per day, which equates to almost one million images per year. It is used to create a personal visual recording of the wearer's life and generates information which can be helpful as a human memory aid. For such a large amount of visual information to be of any use, it is accepted that it should be structured into \\\"events\\\", of which there are about 8,000 in a wearer's average year. In automatically segmenting SenseCam images into events, it will then be useful for users to locate other events similar to a given event e.g. \\\"what other times was I walking in the park?\\\", \\\"show me other events when I was in a restaurant\\\". On two datasets of 240k and 1.8M images containing topics with a variety of information needs, we evaluate the fusion of MPEG-7, SIFT, and SURF content-based retrieval techniques to address the event search issue. We have found that our proposed fusion approach of MPEG-7 and SURF offers an improvement on using either of those sources or SIFT individually, and we have also shown how a lifelog event is modeled has a large effect on the retrieval performance.\",\n \"Title: Dublin City University Video Track Experiments for TREC 2001\\nYear: 2002\\n\\nAbstract: Dublin City University participated in the interactive search task and Shot Boundary Detection task* of the TREC Video Track. In the interactive search task experiment thirty people used three different digital video browsers to find video segments matching the given topics. Each user was under a time constraint of six minutes for each topic assigned to them. The purpose of this experiment was to compare video browsers and so a method was developed for combining independent users' results for a topic into one set of results. Collated results based on thirty users are available herein though individual users' and browsers' results are currently unavailable for comparison. Our purpose in participating in this TREC track was to create the ground truth within the TREC framework, which will allow us to do direct browser performance comparisons.\",\n \"Title: Thermo-visual feature fusion for object tracking using multiple spatiogram trackers\\nYear: 2008\\n\\nAbstract: In this paper, we propose a framework that can efficiently combine features for robust tracking based on fusing the outputs of multiple spatiogram trackers. This is achieved without the exponential increase in storage and processing that other multimodal tracking approaches suffer from. The framework allows the features to be split arbitrarily between the trackers, as well as providing the flexibility to add, remove or dynamically weight features. We derive a mean-shift type algorithm for the framework that allows efficient object tracking with very low computational overhead. We especially target the fusion of thermal infrared and visible spectrum features as the most useful features for automated surveillance applications. Results are shown on multimodal video sequences clearly illustrating the benefits of combining multiple features using our framework.\",\n \"Title: Team activity recognition in sports\\nYear: 2012\\n\\nAbstract: We introduce a novel approach for team activity recognition in sports. Given the positions of team players from a plan view of the playing field at any given time, we solve a particular Poisson equation to generate a smooth distribution defined on whole playground, termed the position distribution of the team. Computing the position distribution for each frame provides a sequence of distributions, which we process to extract motion features for team activity recognition. The motion features are obtained at each frame using frame differencing and optical flow. We investigate the use of the proposed motion descriptors with Support Vector Machines (SVM) classification, and evaluate on a publicly available European handball dataset. Results show that our approach can classify six different team activities and performs better than a method that extracts features from the explicitly defined positions. Our method is new and different from other trajectory-based methods. These methods extract activity features using the explicitly defined trajectories, where the players have specific positions at any given time, and ignore the rest of the playground. In our work, on the other hand, given the specific positions of the team players at a frame, we construct a position distribution for the team on the whole playground and process the sequence of position distribution images to extract motion features for activity recognition. Results show that our approach is effective.\",\n \"Title: Experiences of Aiding Autobiographical Memory Using the SenseCam.\\nYear: 2012\\n\\nAbstract: Human memory is a dynamic system that makes accessible certain memories of events based on a hierarchy of information, arguably driven by personal significance. Not all events are remembered, but those that are tend to be more psychologically relevant. In contrast, lifelogging is the process of automatically recording aspects of one's life in digital form without loss of information. In this article we share our experiences in designing computer-based solutions to assist people review their visual lifelogs and address this contrast. The technical basis for our work is automatically segmenting visual lifelogs into events, allowing event similarity and event importance to be computed, ideas that are motivated by cognitive science considerations of how human memory works and can be assisted. Our work has been based on visual lifelogs gathered by dozens of people, some of them with collections spanning multiple years. In this review article we summarize a series of studies that have led to the development of a browser that is based on human memory systems and discuss the inherent tension in storing large amounts of data but making the most relevant material the most accessible.\",\n \"Title: TRECVid 2006 Experiments at Dublin City University\\nYear: 2006\\n\\nAbstract: In this paper we describe our retrieval system and experiments performed for the automatic search task in TRECVid 2006. We submitted the following six automatic runs: • F A 1 DCU-Base 6: Baseline run using only ASR/MT text features. • F A 2 DCU-TextVisual 2: Run using text and visual features. • F A 2 DCU-TextVisMotion 5: Run using text, visual, and motion features. • F B 2 DCU-Visual-LSCOM 3: Text and visual features combined with concept detectors. • F B 2 DCU-LSCOM-Filters 4: Text, visual, and motion features with concept detectors. • F B 2 DCU-LSCOM-2 1: Text, visual, motion, and concept detectors with negative concepts. The experiments were designed both to study the addition of motion features and separately constructed models for semantic concepts, to runs using only textual and visual features, as well as to establish a baseline for the manually-assisted search runs performed within the collaborative K-Space project and described in the corresponding TRECVid 2006 notebook paper. The results of the experiments indicate that the performance of automatic search can be improved with suitable concept models. This, however, is very topic-dependent and the questions of when to include such models and which concept models should be included, remain unanswered. Secondly, using motion features did not lead to performance improvement in our experiments. Finally, it was observed that our text features, despite displaying a rather poor performance overall, may still be useful even for generic search topics.\",\n \"Title: TRECVid 2007 Experiments at Dublin City University\\nYear: 2007\\n\\nAbstract: In this paper we describe our retrieval system and experiments performed for the auto- matic search task in TRECVid 2007. We submitted the following six automatic runs: • F A 1 DCU-TextOnly6: Baseline run using only ASR/MT text features. • F A 1 DCU-ImgBaseline4: Baseline visual expert only run, no ASR/MT used. Made use of query-time generation of retrieval expert coefficients for fusion. • F A 2 DCU-ImgOnlyEnt5: Automatic generation of retrieval expert coefficients for fusion at index time. • F A 2 DCU-imgOnlyEntHigh3: Combination of coefficient generation which com- bined the coefficients generated by the query-time approach,and the index-time approach, with greater weight given to the index-time coefficient. • F A 2 DCU-imgOnlyEntAuto2: As above, except that greater weight is given to the query-time coefficient that was generated. • F A 2 DCU-autoMixed1: Query-time expert coefficient generation that used both visual and text experts.\",\n \"Title: A user-centric system for home movie summarisation\\nYear: 2011\\n\\nAbstract: In this paper we present a user-centric summarisation system that combines automatic visual-content analysis with user-interface design features as a practical method for home movie summarisation. The proposed summarisation system is designed in such a manner that the video segmentation results generated by the automatic content analysis tools are further subject to refinement through the use of an intuitive user-interface so that the automatically created summaries can be effectively tailored to each individual's personal need. To this end, we study a number of content analysis techniques to facilitate the efficient computation of video summaries, and more specifically emphasise the need for employing an efficient and robust optical flow field computation method for sub-shot segmentation in home movies. Due to the subjectivity of video summarisation and the inherent challenges associated with automatic content analysis, we propose novel user-interface design features as a means to enable the creation of meaningful home movie summaries in a simple manner. The main features of the proposed summarisation system include the ability to automatically create summaries of different visual comprehension, interactively defining the target length of the desired summary, easy and interactive viewing of the content in terms of a storyboard, and manual refinement of the boundaries of the automatically selected video segments in the summary.\",\n \"Title: Mobile multimedia presentation in self-forming mobile device groups: ad-hoc networks in practice\\nYear: 2012\\n\\nAbstract: This demo exhibits a new application of mobile ad-hoc networks, where, a group of mobile devices are connected to allow synchronized presentation of multimedia content. The demo is in the form of an interactive tour. Participants have a mobile device and the tour is led by a guide, who takes the group on an informative tour of a locale. The tour is augmented with the presentation of multimedia content on the devices, highlighting points of interest. Content presentation is controlled by the guide and is synchronized using the ad-hoc network. This is an edutainment application but the underlying technology could be applied elsewhere including educational settings and in entertainment.\",\n \"Title: A comparative evaluation of interactive segmentation algorithms\\nYear: 2010\\n\\nAbstract: In this paper we present a comparative evaluation of four popular interactive segmentation algorithms. The evaluation was carried out as a series of user-experiments, in which participants were tasked with extracting 100 objects from a common dataset: 25 with each algorithm, constrained within a time limit of 2min for each object. To facilitate the experiments, a ''scribble-driven'' segmentation tool was developed to enable interactive image segmentation by simply marking areas of foreground and background with the mouse. As the participants refined and improved their respective segmentations, the corresponding updated segmentation mask was stored along with the elapsed time. We then collected and evaluated each recorded mask against a manually segmented ground truth, thus allowing us to gauge segmentation accuracy over time. Two benchmarks were used for the evaluation: the well-known Jaccard index for measuring object accuracy, and a new fuzzy metric, proposed in this paper, designed for measuring boundary accuracy. Analysis of the experimental results demonstrates the effectiveness of the suggested measures and provides valuable insights into the performance and characteristics of the evaluated algorithms.\",\n \"Title: Rushes video summarization using a collaborative approach\\nYear: 2008\\n\\nAbstract: This paper describes the video summarization system developed by the partners of the K-Space European Network of Excellence for the TRECVID 2008 BBC rushes summarization evaluation. We propose an original method based on individual content segmentation and selection tools in a collaborative system. Our system is organized in several steps. First, we segment the video, secondly we identify relevant and redundant segments, and finally, we select a subset of segments to concatenate and build the final summary with video acceleration incorporated. We analyze the performance of our system through the TRECVID evaluation.\",\n \"Title: Identification of sleep apnea events using discrete wavelet transform of respiration, ECG and accelerometer signals.\\nYear: 2013\\n\\nAbstract: Sleep apnea is a common sleep disorder in which patient sleep patterns are disrupted due to recurrent pauses in breathing or by instances of abnormally low breathing. Current gold standard tests for the detection of apnea events are costly and have the addition of long waiting times. This paper investigates the use of cheap and easy to use sensors for the identification of sleep apnea events. Combinations of respiration, electrocardiography (ECG) and acceleration signals were analysed. Results show that using features, formed using the discrete wavelet transform (DWT), from the ECG and acceleration signals provided the highest classification accuracy, with an F1 score of 0.914. However, the novel employment of just the accelerometer signal during classification provided a comparable F1 score of 0.879. By employing one or a combination of the analysed sensors a preliminary test for sleep apnea, prior to the requirement for gold standard testing, can be performed.\",\n \"Title: Tennissense: a platform for extracting semantic information from multi-camera tennis data\\nYear: 2009\\n\\nAbstract: In this paper, we introduce TennisSense, a technology platform for the digital capture, analysis and retrieval of tennis training and matches. Our algorithms for extracting useful metadata from the overhead court camera are described and evaluated. We track the tennis ball using motion images for ball candidate detection and then link ball candidates into locally linear tracks. From these tracks we can infer when serves and rallies take place. Using background subtraction and hysteresis-type blob tracking, we track the tennis players positions. The performance of both modules is evaluated using ground-truthed data. The extracted metadata provides valuable information for indexing and efficient browsing of hours of multi-camera tennis footage and we briefly illustrative how this data is used by our tennis-coach playback interface.\",\n \"Title: Interactive surveillance event detection at TRECVid2012\\nYear: 2013\\n\\nAbstract: This demonstration shows the integration of video analysis and search tools to facilitate the interactive retrieval of video segments depicting specific activities from surveillance footage. The implementation was developed by members of the SAVASA project for participation in the interactive surveillance event detection (SED) task of TRECVid 2012. This year, for the first time, the purpose of the interactive SED task was to evaluate systems' ability to support users in identifying video segments that depict a specific activity (event) in a large collection of surveillance video footage. Project partners worked together to analyse video and provide a query interface enabling users to search and identify matching video segments. The collaborative integration of components from multiple partners and the participation of end user partners in evaluating the system are the novel aspects of this work.\",\n \"Title: Dynamic Voxel Carving In Tennis Based On Player Localisation Using A Low Cost Camera Network\\nYear: 2011\\n\\nAbstract: In this paper, we address the problem of reconstructing 3D volumetric models, illustrating human sporting performance for use in coaching scenarios. We advocate the use of low cost camera networks for acquiring such data, allowing the approach to be feasibly adopted by both amateur and elite level sports athletes. A dynamic voxel carving approach is described, coupled with over-head player tracking and autonomous background subtraction, to automatically produce a 3D reconstruction technique that intelligently uses memory resources. We demonstrate the efficacy of our approach in the context of tennis as a challenging application scenario.\",\n \"Title: Social recommendation and visual analysis on the TV\\nYear: 2010\\n\\nAbstract: In this paper, we present prototype interactive TV software that incorporates visual content analysis tools and social networking in the home TV. We present the challenges of working with the living room TV environment and outline how we have utilized visual processing and search technologies to address these challenges and create a novel prototype interactive TV system.\",\n \"Title: An information retrieval approach to identifying infrequent events in surveillance video\\nYear: 2013\\n\\nAbstract: This paper presents work on integrating multiple computer vision-based approaches to surveillance video analysis to support user retrieval of video segments showing human activities. Applied computer vision using real-world surveillance video data is an extremely challenging research problem, independently of any information retrieval (IR) issues. Here we describe the issues faced in developing both generic and specific analysis tools and how they were integrated for use in the new TRECVid interactive surveillance event detection task. We present an interaction paradigm and discuss the outcomes from face-to-face end user trials and the resulting feedback on the system from both professionals, who manage surveillance video, and computer vision or machine learning experts. We propose an information retrieval approach to finding events in surveillance video rather than solely relying on traditional annotation using specifically trained classifiers.\",\n \"Title: Implementation and Analysis of Several Keyframe-Based Browsing Interfaces to Digital Video\\nYear: 2000\\n\\nAbstract: In this paper we present a variety of browsing interfaces for digital video information. The six interfaces are implemented on top of Físchlár, an operational recording, indexing, browsing and playback system for broadcast TV programmes. In developing the six browsing interfaces, we have been informed by the various dimensions which can be used to distinguish one interface from another. For this we include layeredness (the number of \\\"layers\\\" of abstraction which can be used in browsing a programme), the provision or omission of temporal information (varying from full timestamp information to nothing at all on time) and visualisation of spatial vs. temporal aspects of the video. After introducing and defining these dimensions we then locate some common browsing interfaces from the literature in this 3-dimensional \\\"space\\\" and then we locate our own six interfaces in this same space. We then present an outline of the interfaces and include some user feedback.\",\n \"Title: Average Precision: Good Guide or False Friend to Multimedia Search Effectiveness?\\nYear: 2014\\n\\nAbstract: Approaches to multimedia search often evolve from existing approaches with strong average precision. However, work on search evaluation shows that average precision does not always capture effectiveness in terms of satisfying user needs because it ignores the diversity of search results. This paper investigates whether search approaches with diverse results have been neglected within the multimedia retrieval research agenda due the fact that they are overshadowed by search approaches with strong average precision. To this end, we compare 361 search approaches applied on the TrecVid benchmarks between 2005 and 2007. We motivate two criteria based on measure correlation and statistical equivalence to estimate whether search approaches with diverse results have been neglected. We show that hypothesized effect indeed occurs in the above examined collections. As a consequence, the research community would benefit from reconsidering existing approaches in the light of diversity.\",\n \"Title: Intelligent Middleware for Adaptive Sensing of Tennis Coaching Sessions\\nYear: 2009\\n\\nAbstract: In professional tennis training matches, the coachneeds to be able to view play from the most appropriate anglein order to monitor players activities. In this paper, we presenta system which can adapt the operation of a series of camerasin order to maintain optimal system performance based on aset of wireless sensors. This setup is used as a testbed for anagent based intelligent middleware that can correlate data frommany different wired and wireless sensors and provide effectivein-situ decision making. The proposed solution is flexible enoughto allow the addition of new sensors and actuators. Within thissetup we also provide details of a case study for the embeddedcontrol of cameras through the use of Ubisense data.\",\n \"Title: Evaluating a dancer's performance using kinect-based skeleton tracking\\nYear: 2011\\n\\nAbstract: In this work, we describe a novel system that automatically evaluates dance performances against a gold-standard performance and provides visual feedback to the performer in a 3D virtual environment. The system acquires the motion of a performer via Kinect-based human skeleton tracking, making the approach viable for a large range of users, including home enthusiasts. Unlike traditional gaming scenarios, when the motion of a user must by kept in synch with a pre-recorded avatar that is displayed on screen, the technique described in this paper targets online interactive scenarios where dance choreographies can be set, altered, practiced and refined by users. In this work, we have addressed some areas of this application scenario. In particular, a set of appropriate signal processing and soft computing methodologies is proposed for temporally aligning dance movements from two different users and quantitatively evaluating one performance against another.\",\n \"Title: Dublin City University at the TRECVid 2008 BBC rushes summarisation task\\nYear: 2008\\n\\nAbstract: We describe the video summarisation systems submitted by Dublin City University to the TRECVid 2008 BBC Rushes Summarisation task. We introduce a new approach to redundant video summarisation based on principal component analysis and linear discriminant analysis. The resulting low dimensional representation of each shot offers a simple way to compare and select representative shots of the original video. The final summary is constructed as a dynamic storyboard. Both types of summaries were evaluated and the results are discussed.\",\n \"Title: Designing a touch-screen sensecam browser to support an aging population\\nYear: 2010\\n\\nAbstract: In this paper, we describe the HCI challenges associated with the novel domain of lifelogging for older users. The SenseCam is a passively capturing wearable camera, worn via a lanyard around the neck and used to create a personal lifelog or visual recording of the wearer's life, which generates information that may be very helpful as a human memory aid. Indeed, given that memory defects are more marked in the elderly, we believe that lifelogging browsing techniques which are considerate of the elderly are imperative. Thus, the challenge tackled in this work was to design and integrate the lifelogging activity supported by new technologies in such a way that can easily be learned and used by older people, enabling them to enhance and enrich their lives with the new technologies. This work provides design practitioners of future lifelogging interfaces early sight of the lessons we have learned in making lifelogging technologies accessible to elderly non-computing literate participants.\",\n \"Title: Low Computational Complexity Variable Block Size (VBS) Partitioning for Motion Estimation Using the Walsh Hadamard Transform (WHT)\\nYear: 2009\\n\\nAbstract: Variable Block Size (VBS) based motion estimation has been adapted in state of the art video coding, such asH.264/AVC, VC-1. However, a low complexity H.264/AVCencoder cannot take advantage of VBS due to its power consumption requirements. In this paper, we present a VBS partition algorithm based on a binary motion edge map without either initial motion estimation or Rate-Distortion (R-D)optimization for selecting modes. The proposed algorithm uses the Walsh Hadamard Transform (WHT) to create a binary edge map, which provides a computational complexity cost effectiveness compared to other light segmentation methods typically used to detect the required region.\",\n \"Title: Freegaming: Mobile, collaborative, adaptive and augmented exergaming\\nYear: 2012\\n\\nAbstract: Addressing the obesity epidemic that plagues many societies remains an outstanding public health issue. One innovative approach to addressing this problem is Exergaming. A combination of \\\"Exercise\\\" and \\\"Gaming\\\", the objective is to motivate people participate in exercise regimes, usually in their home environment. In this paper a more holistic interpretation of this exercise paradigm is proposed. Freegaming augments Exergaming in a number of key dimensions but especially through the promotion of games in outdoor mobile contexts and within a social environment. The design and implementation of a platform for Freegaming is described and illustrated through the description of a sample game.\",\n \"Title: MediAssist: using content-based analysis and context to manage personal photo collections\\nYear: 2006\\n\\nAbstract: We present work which organises personal digital photo collections based on contextual information, such as time and location, combined with content-based analysis such as face detection and other feature detectors. The MediAssist demonstration system illustrates the results of our research into digital photo management, showing how a combination of automatically extracted context and content-based information, together with user annotation, facilitates efficient searching of personal photo collections.\",\n \"Title: Shrec'08 Entry: Multi-View 3d Retrieval Using Multi-Scale Contour Representation\\nYear: 2008\\n\\nAbstract: We describe in this paper a method for 3D shape indexing and retrieval that we apply on three data collections of the SHREC - SHape Retrieval Contest 2008: Stability on watertight, CAD and Generic 3D models. The method is based on a set of 2D multi-views after a pose and scale normalization of the models using Continuous PCA and the enclosing sphere. In all views we extract the models silhouettes and compare them pairwise. To compute the similitude measure we consider the external contour of the silhouettes, we extract their convexities and concavities at different scale levels and we build a multiscale representation. The pairs of contours are then compared by elastic matching achieved by using dynamic programming.\",\n \"Title: I like to log: a questionnaire study towards accessible lifelogging for older users\\nYear: 2010\\n\\nAbstract: Lifelogging is the capture and storage of everyday experiences and the act of reviewing lifelog data can significantly support episodic memory, which is particularly vulnerable to the effects of ageing. To design an accessible lifelogging application for older users we firstly need to explore what lifelogging features the application should include. We carried out a questionnaire study to investigate what lifelogging items people from different age groups are currently collecting. Also of interest to us was what items the participants would like to collect and the differences in lifelogging choices between age groups. The results from this questionnaire will contribute to the design of a lifelogging application which focuses on older users' preferences, motivations and abilities.\",\n \"Title: SenseCam Image Localisation Using Hierarchical SURF Trees\\nYear: 2009\\n\\nAbstract: The SenseCam is a wearable camera that automatically takes photos of the wearer's activities, generating thousands of images per day. Automatically organising these images for efficient search and retrieval is a challenging task, but can be simplified by providing semantic information with each photo, such as the wearer's location during capture time. We propose a method for automatically determining the wearer's location using an annotated image database, described using SURF interest point descriptors. We show that SURF out-performs SIFT in matching SenseCam images and that matching can be done efficiently using hierarchical trees of SURF descriptors. Additionally, by re-ranking the top images using bi-directional SURF matches, location matching performance is improved further.\",\n \"Title: Real-time head nod and shake detection for continuous human affect recognition\\nYear: 2013\\n\\nAbstract: Human affect recognition is the field of study associated with using automatic techniques to identify human emotion or human affective state. A person's affective states is often communicated non-verbally through body language. A large part of human body language communication is the use of head gestures. Almost all cultures use subtle head movements to convey meaning. Two of the most common and distinct head gestures are the head nod and the head shake gestures. In this paper we present a robust system to automatically detect head nod and shakes. We employ the Microsoft Kinect and utilise discrete Hidden Markov Models (HMMs) as the backbone to a machine learning based classifier within the system. The system achieves 86% accuracy on test datasets and results are provided.\",\n \"Title: Word matching using single closed contours for indexing handwritten historical documents\\nYear: 2007\\n\\nAbstract: Effective indexing is crucial for providing convenient access to scanned versions of large collections of historically valuable handwritten manuscripts. Since traditional handwriting recognizers based on optical character recognition (OCR) do not perform well on historical documents, recently a holistic word recognition approach has gained in popularity as an attractive and more straightforward solution (Lavrenko et al. in proc. document Image Analysis for Libraries (DIAL'04), pp. 278---287, 2004). Such techniques attempt to recognize words based on scalar and profile-based features extracted from whole word images. In this paper, we propose a new approach to holistic word recognition for historical handwritten manuscripts based on matching word contours instead of whole images or word profiles. The new method consists of robust extraction of closed word contours and the application of an elastic contour matching technique proposed originally for general shapes (Adamek and O'Connor in IEEE Trans Circuits Syst Video Technol 5:2004). We demonstrate that multiscale contour-based descriptors can effectively capture intrinsic word features avoiding any segmentation of words into smaller subunits. Our experiments show a recognition accuracy of 83%, which considerably exceeds the performance of other systems reported in the literature.\",\n \"Title: Toward Automatic Activity Classification and Movement Assessment During a Sports Training Session\\nYear: 2015\\n\\nAbstract: Motion analysis technologies have been widely used to monitor the potential for injury and enhance athlete performance. However, most of these technologies are expensive, can only be used in laboratory environments, and examine only a few trials of each movement action. In this paper, we present a novel ambulatory motion analysis framework using wearable inertial sensors to accurately assess all of an athlete's activities in real training environment. We first present a system that automatically classifies a large range of training activities using the discrete wavelet transform (DWT) in conjunction with a random forest classifier. The classifier is capable of successfully classifying various activities with up to 98% accuracy. Second, a computationally efficient gradient descent algorithm is used to estimate the relative orientations of the wearable inertial sensors mounted on the shank, thigh, and pelvis of a subject, from which the flexion-extension knee and hip angles are calculated. These angles, along with sacrum impact accelerations, are automatically extracted for each stride during jogging. Finally, normative data are generated and used to determine if a subject's movement technique differed to the normative data in order to identify potential injury-related factors. For the joint angle data, this is achieved using a curve-shift registration technique. It is envisaged that the proposed framework could be utilized for accurate and automatic sports activity classification and reliable movement technique evaluation in various unconstrained environments for both injury management and performance enhancement.\",\n \"Title: Object Segmentation in Images using EEG Signals\\nYear: 2014\\n\\nAbstract: This paper explores the potential of brain-computer interfaces in segmenting objects from images. Our approach is centered around designing an effective method for displaying the image parts to the users such that they generate measurable brain reactions. When an image region, specifically a block of pixels, is displayed we estimate the probability of the block containing the object of interest using a score based on EEG activity. After several such blocks are displayed, the resulting probability map is binarized and combined with the GrabCut algorithm to segment the image into object and background regions. This study shows that BCI and simple EEG analysis are useful in locating object boundaries in images.\",\n \"Title: Life-Long Collections: Motivations and the Implications for Lifelogging with Mobile Devices\\nYear: 2014\\n\\nAbstract: In this paper the authors investigate the motivations for life-long collections and how these motivations can inform the design of future lifelog systems. Lifelogging is the practice of automatically capturing data from daily life experiences with mobile devices, such as smartphones and wearable cameras. Lifelog archives can benefit both older and younger people; therefore lifelog systems should be designed for people of all ages. The authors believe that people would be more likely to adopt lifelog practices that support their current motivations for collecting items. To identify these motivations, ten older and ten younger participants were interviewed. It was found that motivations for and against life-long collections evolve as people age and enter different stages, and that family is at the core of life-long collections. These findings will be used to guide the design of an intergenerational lifelog browser.\",\n \"Title: Automatic Activity Classification and Movement Assessment During a Sports Training Session Using Wearable Inertial Sensors\\nYear: 2014\\n\\nAbstract: Motion analysis technologies have been widely used to monitor the potential for injury and enhance athlete performance. However, most of these technologies are expensive, can only be used in laboratory environments and examine only a few trials of each movement action. In this paper, we present a novel ambulatory motion analysis framework using wearable inertial sensors to accurately assess all of an athlete's activities in an outdoor training environment. We firstly present a system that automatically classifies a large range of training activities using the Discrete Wavelet Transform (DWT) in conjunction with a Random forest classifier. The classifier is capable of successfully classifying various activities with up to 98% accuracy. Secondly, a computationally efficient gradient descent algorithm is used to estimate the relative orientations of the wearable inertial sensors mounted on the thigh and shank of a subject, from which the flexion-extension knee angle is calculated. Finally, a curve shift registration technique is applied to both generate normative data and determine if a subject's movement technique differed to the normative data in order to identify potential injury related factors. It is envisaged that the proposed framework could be utilized for accurate and automatic sports activity classification and reliable movement technique evaluation in various unconstrained environments.\",\n \"Title: Low-cost accurate skeleton tracking based on fusion of kinect and wearable inertial sensors\\nYear: 2014\\n\\nAbstract: In this paper, we present a novel multi-sensor fusion method to build a human skeleton. We propose to fuse the joint position information obtained from the popular Kinect sensor with more precise estimation of body segment orientations provided by a small number of wearable inertial sensors. The use of inertial sensors can help to address many of the well known limitations of the Kinect sensor. The precise calculation of joint angles potentially allows the quantification of movement errors in technique training, thus facilitating the use of the low-cost Kinect sensor for accurate biomechanical purposes e.g. the improved human skeleton could be used in visual feedback-guided motor learning, for example. We compare our system to the gold standard Vicon optical motion capture system, proving that the fused skeleton achieves a very high level of accuracy.\",\n \"Title: Interactive games for preservation and promotion of sporting movements\\nYear: 2014\\n\\nAbstract: In this paper we describe two interactive applications for capturing the motion signatures associated with key skills of traditional sports and games. We first present the case for sport as an important example of intangible cultural heritage. We then explain that sport requires special consideration in terms of digitization for preservation as the key aspects to be digitized are the characteristic movement signatures of such sports. We explain that, given the nature of traditional sporting agencies, this requires low-cost motion capture technology. Furthermore we argue that in order to ensure ongoing preservation, this should be provided via fun interactive gaming scenarios that promote uptake of the sports, particularly among children. We then present two such games that we have developed and illustrate their performance.\",\n \"Title: Capturing The Sporting Heroes Of Our Past By Extracting 3d Movements From Legacy Video Content\\nYear: 2014\\n\\nAbstract: Ports are a key part of cultural identity, and it is necessary to preserve them as important intangible Cultural Heritage, especially the human motion techniques specific to individual sports. In this paper we present a method for extracting 3D athlete motion from video broadcast sources, providing an important tool for preserving the heritage represented by these movements. Broadcast videos include camera motion, multiple player interaction, occlusions and noise, presenting significant challenges to solve the reconstruction. The approach requires initial definition of some key-frames and setting of 2D key-points in those frames manually. Thereafter an automatic process estimates the poses and positions of the players in the key-frames, and in the frames between key-frames, taking into account collisions with the environment and human kinematic constraints. Initial results are extremely promising and this data could be used to analyze the sport's evolution over time, or even to generate animations for interactive applications.\",\n \"Title: SEAMLOC: Seamless Indoor Localization Based on Reduced Number of Calibration Points\\nYear: 2014\\n\\nAbstract: Indoor localization based on ubiquitous WLAN has exhibited the capability of being a cheap and relatively precise technology and has been verified by many successful examples. Its performance is subject to change due to multipath propagation and changes in the environment (people, building layouts, antenna characteristics, etc.) which cannot be eliminated easily. An indoor localization and tracking algorithm is described which is based on the creation of a database of WLAN signal strengths at pre-chosen calibration points (CPs). The need for fewer CPs than in standard methods is due to use of a novel interpolation algorithm, based on the specification of robust, range and angle-dependent likelihood functions that describe the probability of a user being in the vicinity of each CP. The actual location of the user is estimated by solving a system of two non-linear equations with two unknowns derived for a pair of CPs. Different pairs of CPs can be chosen to make several estimates which then can be combined to increase the accuracy of the estimate. A variety of results are presented using challenging data collected in a typical office environment which demonstrate the accuracy that can be achieved with a reduced number of CPs.)) The method is compared to several competing localization methods and is shown to give superior results.\",\n \"Title: An Improved Spatiogram Similarity Measure for Robust Object Localisation\\nYear: 2007\\n\\nAbstract: Spatiograms were introduced as a generalisation of the com- monly used histogram, providing the flexibility of adding spa- tial context information to the feature distribution information of a histogram. The originally proposed spatiogram com- parison measure has significant disadvantages that we detail here. We propose an improved measure based on deriving the Bhattacharyya coefficient for an infinite number of spatial- feature bins. Its advantages over the previous measure and over histogram-based matching are demonstrated in object tracking scenarios.\",\n \"Title: Optimising resource allocation for background modeling using algorithm switching\\nYear: 2008\\n\\nAbstract: Background maintenance is a complex problem due to varying scene conditions. Typically, a single algorithm cannot handle the complex scene changes that occur in visual surveillance applications. Also complex background modelling techniques, for example mixture of Gaussians have a high computational and communication demand compared to simple techniques such as a uni-model background model or simple frame-differencing with an adaptive threshold. In this paper we present an algorithm switching approach that can handle multi-model background scenes. Starting with a less computational and less data intensive uni-model background subtraction algorithm the system switches to a complex multi-model background subtraction there by saving valuable software and hardware resources both in terms of power and computation time. Our results show this algorithm switching approach can be used to effectively handle various scene conditions encountered in real time surveillance systems with optimal use of system resources.\",\n \"Title: Visualisation of tennis swings for coaching\\nYear: 2012\\n\\nAbstract: As a proficient tennis swing is a key element of success in tennis, many amateur tennis players spend a considerable amount of time and effort perfecting their tennis stroke mechanics, hoping to create more accuracy, consistency and power in their swing. In order to achieve these aims effectively a number of independent aspects of technique need to be addressed, including forming a correct racket grip, shot timing, body orientation and precise follow-through. Outside of a one-to-one coaching scenario, where constant professional feedback on technique can be provided, keeping all aspects of technique in mind can overwhelm amateur players. In this work, we have developed a set of visualisation tools to augment the development of amateur tennis players between dedicated one-to-one coaching sessions in the area of technique, timing and body posture. Our approach temporally aligns an amateur player's swing dynamics with that of an elite athlete, allowing direct technique comparison using augmented reality techniques.\",\n \"Title: Investigating older and younger peoples' motivations for lifelogging with wearable cameras\\nYear: 2013\\n\\nAbstract: People have a natural tendency to collect things about themselves, their experiences and their shared experiences with people important to them, especially family. Similar to traditional objects such as photographs, lifelogs have been shown to support reminiscence. A lifelog is a digital archive of a person's experiences and activities and lifelog devices such as wearable cameras can automatically and continuously record events throughout a whole day. We were interested in investigating what would motivate people to lifelog. Due to the importance of shared family reminiscence between family members we focused our study on comparing shared or personal motivations with ten older and ten younger family members. We found from our results that both older and younger adults were more likely to lifelog for the purposes of information sharing and that reviewing lifelog images supported family reminiscence, reflection and story-telling. Based on these findings, recommendations are made for the design of a novel intergenerational family lifelog system.\",\n \"Title: Identifying an efficient and robust sub-shot segmentation method for home movie summarisation\\nYear: 2010\\n\\nAbstract: With the increasing volumes of home video footage and the need for effectively managing such archives, home movie summarisation has become an important and key research topic in the recent past. Despite growing interest from the research community, automatic summarisation remains a challenging research problem due to unrestricted capture and lack of storyline present in the home video content. In this paper, we address a sub-problem of the broad summarisation problem, namely sub-shot segmentation, as an important content analysis step in home movie summarisation. More specifically, we conduct an experimental study to identify an efficient and robust sub-shot segmentation method through a performance comparison of a number of optical flow field computation methods. Formulating the task of sub-shot segmentation as a process of decomposing a raw video into different video segments in line with the change in dominant camera motion, we are interested in detecting the most useful camera motions we have observed in real collections, namely pan, tilt and zoom. To this end, a number of feature-based optical flow field computation methods, including two well-known local feature descriptors called SIFT and SURF, and the Pyramidal Lucas-Kanade (PLK) local feature tracker, are investigated as potentially useful approaches for facilitating efficient and robust sub-shot segmentation in this paper. We then compare the performance of those algorithms with 5 different block matching motion estimation algorithms. Simulation results show that the PLK algorithm outperforms the SIFT and SURF algorithms in terms of both accuracy and efficiency. Furthermore, despite its slightly lower accuracy compared to that of the most optimal block matching algorithms (BMA), we conclude that a local feature tracker like the PLK algorithm is the preferred choice for sub-shot detection in real-life home movie archives due to the trade-off it provides between accuracy and efficiency.\",\n \"Title: Action recognition based on sparse motion trajectories\\nYear: 2013\\n\\nAbstract: We present a method that extracts effective features in videos for human action recognition. The proposed method analyses the 3D volumes along the sparse motion trajectories of a set of interest points from the video scene. To represent human actions, we generate a Bag-of-Features (BoF) model based on extracted features, and finally a support vector machine is used to classify human activities. Evaluation shows that the proposed features are discriminative and computationally efficient. Our method achieves state-of-the-art performance with the standard human action recognition benchmarks, namely KTH and Weizmann datasets.\",\n \"Title: Game, shot and match: Event-based indexing of tennis\\nYear: 2011\\n\\nAbstract: Identifying events in sports video offers great potential for advancing visual sports coaching applications. In this paper, we present our results for detecting key events in a tennis match. Our overall goal is to automatically index a complete tennis match into all the main tennis events, so that a match can be recorded using affordable visual sensing equipment and then be automatically indexed into key events for retrieval and editing. The tennis events detected in this paper are a tennis game, a change of end and a tennis serve - all of which share temporal commonalities. There are of course other events in tennis which we aim to index in our overall indexing system, but this paper focuses solely on the aforementioned tennis events. This paper proposes a novel approach to detect key events in an instrumented tennis environment by analysing a players location and the visual features of a player.\",\n \"Title: Visual analysis for drum sequence transcription\\nYear: 2007\\n\\nAbstract: A system is presented for analysing drum performance video se- quences. A novel ellipse detection algorithm is introduced that au- tomatically locates drum tops. This algorithm fits ellipses to edge clusters, and ranks them according to various fitness criteria. A background/foreground segmentation method is then used to extract the silhouette of the drummer and drum sticks. Coupled with a mo- tion intensity feature, this allows for the detection of 'hits' in each of the extracted regions. In order to obtain a transcription of the performance, each of these regions is automatically labeled with the corresponding instrument class. A partial audio transcription and color cues are used to measure the compatibility between a re- gion and its label, the Kuhn-Munkres algorithm is then employed to find the optimal labeling. Experimental results demonstrate the ability of visual analysis to enhance the performance of an audio drum transcription system.\",\n \"Title: Team behavior analysis in sports using the Poisson equation\\nYear: 2012\\n\\nAbstract: We propose a novel physics-based model for analysing team players' positions and movements on a sports playing field. The goal is to detect for each frame the region with the highest population of a given team's players and the region towards which the team is moving as they press for territorial advancement, termed the region of intent. Given the positions of team players from a plan view of the playing field at any given time, we solve a particular Poisson equation to generate a smooth distribution. The proposed distribution provides the likelihood of a point to be occupied by players so that more highly populated regions can be detected by appropriate thresholding. Computing the proposed distribution for each frame provides a sequence of distributions, which we process to detect the region of intent at any time during the game. Our model is evaluated on a field hockey dataset, and results show that the proposed approach can provide effective features that could be used to generate team statistics useful for performance evaluation or broadcasting purposes.\",\n \"Title: Low-Energy Symmetric Key Distribution in Wireless Sensor Networks\\nYear: 2011\\n\\nAbstract: In this work, a scheme for key distribution and network access in a Wireless Sensor Network (WSN) that utilizes Identity-Based Cryptography (IBC) is presented. The scheme is analyzed on the ARM920T processor and measurements were taken for the runtime and energy of its components. It was found that the Tate pairing component of the scheme consumes significant amounts of energy, and so should be ported to hardware. An accelerator was implemented in 65 nm Complementary Metal Oxide Silicon (CMOS) technology and area, timing, and energy figures have been obtained for the design. Results indicate that a hardware implementation of IBC would meet the strict energy constraint required of a wireless sensor network node.\",\n \"Title: Remote real-time monitoring of subsurface landfill gas migration.\\nYear: 2011\\n\\nAbstract: The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months.\",\n \"Title: A neural network approach to smarter sensor networks for water quality monitoring.\\nYear: 2012\\n\\nAbstract: Environmental monitoring is evolving towards large-scale and low-cost sensor networks operating reliability and autonomously over extended periods of time. Sophisticated analytical instrumentation such as chemo-bio sensors present inherent limitations because of the number of samples that they can take. In order to maximize their deployment lifetime, we propose the coordination of multiple heterogeneous information sources. We use rainfall radar images and information from a water depth sensor as input to a neural network (NN) to dictate the sampling frequency of a phosphate analyzer at the River Lee in Cork, Ireland. This approach shows varied performance for different times of the year but overall produces output that is very satisfactory for the application context in question. Our study demonstrates that even with limited training data, a system for controlling the sampling rate of the nutrient sensor can be set up and can improve the efficiency of the more sophisticated nodes of the sensor network.\",\n \"Title: Classification of sporting activities using smartphone accelerometers.\\nYear: 2013\\n\\nAbstract: In this paper we present a framework that allows for the automatic identification of sporting activities using commonly available smartphones. We extract discriminative informational features from smartphone accelerometers using the Discrete Wavelet Transform (DWT). Despite the poor quality of their accelerometers, smartphones were used as capture devices due to their prevalence in today's society. Successful classification on this basis potentially makes the technology accessible to both elite and non-elite athletes. Extracted features are used to train different categories of classifiers. No one classifier family has a reportable direct advantage in activity classification problems to date; thus we examine classifiers from each of the most widely used classifier families. We investigate three classification approaches; a commonly used SVM-based approach, an optimized classification model and a fusion of classifiers. We also investigate the effect of changing several of the DWT input parameters, including mother wavelets, window lengths and DWT decomposition levels. During the course of this work we created a challenging sports activity analysis dataset, comprised of soccer and field-hockey activities. The average maximum F-measure accuracy of 87% was achieved using a fusion of classifiers, which was 6% better than a single classifier model and 23% better than a standard SVM approach.\",\n \"Title: The Convergence of Virtual Reality and Social Networks: Threats to Privacy and Autonomy.\\nYear: 2016\\n\\nAbstract: The rapid evolution of information, communication and entertainment technologies will transform the lives of citizens and ultimately transform society. This paper focuses on ethical issues associated with the likely convergence of virtual realities (VR) and social networks (SNs), hereafter VRSNs. We examine a scenario in which a significant segment of the world's population has a presence in a VRSN. Given the pace of technological development and the popularity of these new forms of social interaction, this scenario is plausible. However, it brings with it ethical problems. Two central ethical issues are addressed: those of privacy and those of autonomy. VRSNs pose threats to both privacy and autonomy. The threats to privacy can be broadly categorized as threats to informational privacy, threats to physical privacy, and threats to associational privacy. Each of these threats is further subdivided. The threats to autonomy can be broadly categorized as threats to freedom, to knowledge and to authenticity. Again, these three threats are divided into subcategories. Having categorized the main threats posed by VRSNs, a number of recommendations are provided so that policy-makers, developers, and users can make the best possible use of VRSNs.\",\n \"Title: A multi-modal dance corpus for research into interaction between humans in virtual environments\\nYear: 2013\\n\\nAbstract: We present a new, freely available, multimodal corpus for research into, amongst other areas, real-time realistic interaction between humans in online virtual environments. The specific corpus scenario focuses on an online dance class application scenario where students, with avatars driven by whatever 3D capture technology is locally available to them, can learn choreographies with teacher guidance in an online virtual dance studio. As the dance corpus is focused on this scenario, it consists of student/teacher dance choreographies concurrently captured at two different sites using a variety of media modalities, including synchronised audio rigs, multiple cameras, wearable inertial measurement devices and depth sensors. In the corpus, each of the several dancers performs a number of fixed choreographies, which are graded according to a number of specific evaluation criteria. In addition, ground-truth dance choreography annotations are provided. Furthermore, for unsynchronised sensor modalities, the corpus also includes distinctive events for data stream synchronisation. The total duration of the recorded content is 1 h and 40 min for each single sensor, amounting to 55 h of recordings across all sensors. Although the dance corpus is tailored specifically for an online dance class application scenario, the data is free to download and use for any research and development purposes.\",\n \"Title: Real-time event classification in field sport videos\\nYear: 2015\\n\\nAbstract: The paper presents a novel approach to real-time event detection in sports broadcasts. We present how the same underlying audio-visual feature extraction algorithm based on new global image descriptors is robust across a range of different sports alleviating the need to tailor it to a particular sport. In addition, we propose and evaluate three different classifiers in order to detect events using these features: a feed-forward neural network, an Elman neural network and a decision tree. Each is investigated and evaluated in terms of their usefulness for real-time event classification. We also propose a ground truth dataset together with an annotation technique for performance evaluation of each classifier useful to others interested in this problem. HighlightsArticle presents novel system for real-time video indexing for field sports videos based on the new video description technique.Up to date there is no system that covers so many different sports genres, features so high accuracy and is capable of working in real-time.Several classifiers were compared in the results section which gives additional knowledge about the system features.\",\n \"Title: Improving object segmentation by using EEG signals and rapid serial visual presentation\\nYear: 2015\\n\\nAbstract: This paper extends our previous work on the potential of EEG-based brain computer interfaces to segment salient objects in images. The proposed system analyzes the Event Related Potentials (ERP) generated by the rapid serial visual presentation of windows on the image. The detection of the P300 signal allows estimating a saliency map of the image, which is used to seed a semi-supervised object segmentation algorithm. Thanks to the new contributions presented in this work, the average Jaccard index was improved from 0.47 to 0.66 when processed in our publicly available dataset of images, object masks and captured EEG signals. This work also studies alternative architectures to the original one, the impact of object occupation in each image window, and a more robust evaluation based on statistical analysis and a weighted F-score.\",\n \"Title: Automatically detecting asymmetric running using time and frequency domain features\\nYear: 2015\\n\\nAbstract: Human motion analysis technologies have been widely employed to identify injury determining factors and provide objective and quantitative feedback to athletes to help prevent injury. However, most of these technologies are: expensive, restricted to laboratory environments, and can require significant post processing. This reduces their ecological validity, adoption and usefulness. In this paper, we present a novel wearable inertial sensor framework to accurately distinguish between symmetrical and asymmetrical running patterns in an unconstrained environment. The framework can automatically classify symmetry/asymmetry using Short Time Fourier Transform (STFT) and other time domain features in conjunction with a customized Random Forest classifier. The accuracy of the designed framework is up to 94% using 3-D accelerometer and 3-D gyroscope data from a sensor node attached on the upper back of a subject. The upper back inertial sensors data were then down-sampled by a factor of 4 to simulate utilizing low-cost inertial sensors whilst also facilitating a decrease of the computational cost to achieve near real-time application. We conclude that the proposed framework can potentially pave the way for employing low-cost sensors, such as those used in smartphones, attached on the upper back to provide injury related and performance feedback in real-time in unconstrained environments.\",\n \"Title: HeartHealth: New Adventures in Serious Gaming\\nYear: 2015\\n\\nAbstract: We present a novel, low-cost, interactive, exercise-based rehabilitation system. Our research involves the investigation and development of patient-centric, sensor-based rehabilitation games and surrounding technologies. HeartHealth is designed to provide a safe, personalised and fun exercise environment that could be deployed in any exercise based rehabilitation program. HeartHealth utilises a cloud-based patient information management system built on FIWARE Generic Enablers,and motion tracking coupled with our sophisticated motion comparison algorithms. Users can record customised exercises through a doctors interface and then play the rehabilitation game where they must perform a sequence of their exercises in order to complete the game scenario. Their exercises are monitored, recorded and compared by our Motion Evaluation software and real-time feedback is than given based on the users performance.\",\n \"Title: A Multi-Modal 3D Capturing Platform for Learning and Preservation of Traditional Sports and Games\\nYear: 2015\\n\\nAbstract: We present a demonstration of a multi-modal 3D capturing platform coupled to a motion comparison system. This work is focused on the preservation of Traditional Sports and Games, namely the Gaelic sports from Ireland and Basque sports from France and Spain. Users can learn, compare and compete in the performance of sporting gestures and compare themselves to real athletes. Our online gesture database provides a way to preserve and display a wide range of sporting gestures. The capturing devices utilised are Kinect 2 sensors and wearable inertial sensors, where the number required varies based on the requested scenario. The fusion of these two capture modalities, coupled to our inverse kinematic algorithm, allow us to synthesize a fluid and reliable 3D model of the user gestures over time. Our novel comparison algorithms provide the user with a performance score and a set of comparison curves (i.e. joint angles and angular velocities), providing a precise and valuable feedback for coaches and players.\",\n \"Title: Combining inertial and visual sensing for human action recognition in tennis\\nYear: 2010\\n\\nAbstract: In this paper, we present a framework for both the automatic extraction of the temporal location of tennis strokes within a match and the subsequent classification of these as being either a serve, forehand or backhand. We employ the use of low-cost visual sensing and low-cost inertial sensing to achieve these aims, whereby a single modality can be used or a fusion of both classification strategies can be adopted if both modalities are available within a given capture scenario. This flexibility allows the framework to be applicable to a variety of user scenarios and hardware infrastructures. Our proposed approach is quantitatively evaluated using data captured from elite tennis players. Results point to the extremely accurate performance of the proposed approach irrespective of input modality configuration\",\n \"Title: The Real Time Rolling Shutter\\nYear: 2015\\n\\nAbstract: From an early age children are often told either, you are creative you should do art but stay away from science and maths. Or that you are mathematical you should do science but you're not that creative. Compounding this there also exist some traditional barriers of artistic rhetoric that say, \\\"don't touch, don't think and don't be creative, we've already done that for you, you can just look...\\\". The Real Time Rolling Shutter is part of a collaborative Art/Science partnership whose core tenets are in complete contrast to this. The Art/Science exhibitions we have created have invited the public to become part of the exhibition by utilising augmented digital mirrors, Kinects, feed-back camera and projector systems and augmented reality perception helmets. The fundamental underlying principles we are trying to adhere to are to foster curiosity, intrigue, wonderment and amazement and we endeavour to draw the audience into the interactive nature of our exhibits and exclaim to everyone that you can be what ever you chose to be, and that everyone can be creative, everyone can be an artist, everyone can be a scientist... all it takes is an inquisitive mind, so come and explore the real-time rolling shutter and be creative.\",\n \"Title: Background Modelling in Infrared and Visible Spectrum Video for People Tracking\\nYear: 2005\\n\\nAbstract: In this paper, we present our approach to robust background modelling which combines visible and thermal infrared spectrum data. Our work is based on the non-parametric background model describe in 1. We use a pedestrian detection module to prevent erroneous data from becoming part of the background model and this allows us to initialise our bacjground model, even in the presence of foreground objects. Visible and infrared features are use to remove incorrectly detected foreground regions. Allowing our model to quickly recover from ghost regions and rapid lighting changes. An object-basedshadow detector also improves our algorithm's performance.\",\n \"Title: LoggerMan, a Comprehensive Logging and Visualization Tool to Capture Computer Usage.\\nYear: 2016\\n\\nAbstract: As we become increasingly dependent on our computers and spending a major part of our day interacting with these machines, it is becoming important for lifeloggers and Human-Computer Interaction (HCI) researchers to capture this aspect of our life. In this paper, we present LoggerMan, a comprehensive logging tool to capture many aspects of our computer usage. It also comes with reporting capabilities to give insights to the data owner about his/her computer usage. In this work, we aim to address the current lack of logging software in this domain, which would help us, and other researchers, to build datasets for HCI experiments and also to better understand computer usage patterns. Our tool is published online (http://loggerman.org/) to be used freely by the community.\",\n \"Title: Exploring EEG for Object Detection and Retrieval.\\nYear: 2015\\n\\nAbstract: This paper explores the potential for using Brain Computer Interfaces (BCI) as a relevance feedback mechanism in content-based image retrieval. Several experiments are performed using a rapid serial visual presentation (RSVP) of images at different rates (5Hz and 10Hz) on 8 users with different degrees of familiarization with BCI and the dataset. We compare the feedback from the BCI and mouse-based interfaces in a subset of TRECVid images, finding that, when users have limited time to annotate the images, both interfaces are comparable in performance. Comparing our best users in a retrieval task, we found that EEG-based relevance feedback can outperform mouse-based feedback.\",\n \"Title: HeartHealth: A cardiovascular disease home-based rehabilitation system\\nYear: 2015\\n\\nAbstract: The increasing pressure on medical institutions around the world requires health care professionals to be prescribing home- based exercise rehabilitation treatments to empower patients to self-monitor their rehabilitation journey. Home-based exercise rehabilitation has shown to be highly effective in treating conditions such as Cardiovascular Disease (CVD). However, adherence to home-based exercise rehabilitation remains low. Possible causes for this are that patients are not monitored, they cannot be con- fident that they are performing the exercise correctly or accurately and they receive no feedback. This paper proposes HeartHealth, a novel patient-centric gamified exercise rehabilitation platform that can help address the issue of adherence to these programmes. The key functionality is the ability to record the patient movements and compare them against the exercises that have been pre- scribed in order to return feedback to the patient and to the health care professional, as well. In order to synthesize a compact fully operational system able to work in real life scenarios, tools and services from FI-PPP projects, FIWARE 1 and FI-STAR 2, were exploited and a new FI-STAR component, Motion Evaluation Specific Enabler (SE), was designed and developed. The HeartHealth system brings together real-time cloud-based motion evaluation coupled with accurate low-cost motion capture, a personalised ex- ercise rehabilitation programme and an intuitive and fun serious game interface, designed specifically with a Cardiac Rehabilitation population in mind.\",\n \"Title: Action recognition in video using a spatial-temporal graph-based feature representation\\nYear: 2015\\n\\nAbstract: We propose a video graph based human action recognition framework. Given an input video sequence, we extract spatio-temporal local features and construct a video graph to incorporate appearance and motion constraints to reflect the spatio-temporal dependencies among features. them. In particular, we extend a popular dbscan density-based clustering algorithm to form an intuitive video graph. During training, we estimate a linear SVM classifier using the standard Bag-of-words method. During classification, we apply Graph-Cut optimization to find the most frequent action label in the constructed graph and assign this label to the test video sequence. The proposed approach achieves state-of-the-art performance with standard human action recognition benchmarks, namely KTH and UCF-sports datasets and competitive results for the Hollywood (HOHA) dataset.\",\n \"Title: Bags of Local Convolutional Features for Scalable Instance Search.\\nYear: 2016\\n\\nAbstract: This work proposes a simple instance retrieval pipeline based on encoding the convolutional features of CNN using the bag of words aggregation scheme (BoW). Assigning each local array of activations in a convolutional layer to a visual word produces an assignment map, a compact representation that relates regions of an image with a visual word. We use the assignment map for fast spatial reranking, obtaining object localizations that are used for query expansion. We demonstrate the suitability of the BoW representation based on local CNN features for instance retrieval, achieving competitive performance on the Oxford and Paris buildings benchmarks. We show that our proposed system for CNN feature aggregation with BoW outperforms state-of-the-art techniques using sum pooling at a subset of the challenging TRECVid INS benchmark.\",\n \"Title: Introduction to the Issue on Person-Centered Signal Processing for Assistive, Rehabilitative, and Wearable Health Technologies.\\nYear: 2016\\n\\nAbstract: The thirteen papers in this special issue aims to bring awareness to the need and importance of person-centered design in computing and signal processing solutions, and presents advances in person-centered signal processing for assistive, rehabilitative, and wearable health technologies.\",\n \"Title: Designing a Topological Algorithm for 3D Activity Recognition.\\nYear: 2016\\n\\nAbstract: Voxel carving is a non-invasive and low-cost technique that is used for the reconstruction of a 3D volume from images captured from a set of cameras placed around the object of interest. In this paper we propose a method to topologically analyze a video sequence of 3D reconstructions representing a tennis player performing different forehand and backhand strokes with the aim of providing an approach that could be useful in other sport activities.\",\n \"Title: Where is my Phone ? Personal Object Retrieval from Egocentric Images.\\nYear: 2016\\n\\nAbstract: This work presents a retrieval pipeline and evaluation scheme for the problem of finding the last appearance of personal objects in a large dataset of images captured from a wearable camera. Each personal object is modelled by a small set of images that define a query for a visual search engine.The retrieved results are reranked considering the temporal timestamps of the images to increase the relevance of the later detections. Finally, a temporal interleaving of the results is introduced for robustness against false detections. The Mean Reciprocal Rank is proposed as a metric to evaluate this problem. This application could help into developing personal assistants capable of helping users when they do not remember where they left their personal belongings.\",\n \"Title: A Multimodal Gamified Platform for Real-Time User Feedback in Sports Performance.\\nYear: 2016\\n\\nAbstract: In this paper we introduce a novel platform that utilises multi-modal low-cost motion capture technology for the delivery of real-time visual feedback for sports performance. This platform supports the expansion to multi-modal interfaces that utilise haptic and audio feedback, which scales effectively with motor task complexity. We demonstrate an implementation of our platform within the field of sports performance. The platform includes low-cost motion capture through a fusion technique, combining a Microsoft Kinect V2 with two wrist inertial sensors, which make use of the accelerometer and gyroscope sensors, alongside a game-based Graphical User Interface (GUI) for instruction, visual feedback and gamified score tracking.\",\n \"Title: Vector Quantization Enhancement for Computer Vision Tasks.\\nYear: 2016\\n\\nAbstract: This paper augments the Bag-of-Word scheme in several respects: we incorporate a category label into the clustering process, build classifier-tailored codebooks, and weight codewords according to their probability to occur. A size-adaptive feature clustering algorithm is also proposed as an alternative to k-means. Experiments on the PASCAL VOC 2007 challenge validate the approach for classical hard-assignment as well as VLAD encoding.\",\n \"Title: TREAT: Terse Rapid Edge-Anchored Tracklets\\nYear: 2016\\n\\nAbstract: Fast computation, efficient memory storage, and performance on par with standard state-of-the-art descriptors make binary descriptors a convenient tool for many computer vision applications. However their development is mostly tailored for static images. To respond to this limitation, we introduce TREAT (Terse Rapid Edge-Anchored Tracklets), a new binary detector and descriptor, based on tracklets. It harnesses moving edge maps to perform efficient feature detection, tracking, and description at low computational cost. Experimental results on 3 different public datasets demonstrate improved performance over other popular binary features. These experiments also provide a basis for benchmarking the performance of binary descriptors in video-based applications.\",\n \"Title: A flexible ensemble-SVM for computer vision tasks\\nYear: 2016\\n\\nAbstract: This paper presents an ensemble-SVM method that features a data selection mechanism with stochastic and deterministic properties, the use of extreme value theory for classifier calibration, and the introduction of random forest for classifier combination. We applied the proposed algorithm to 2 event recognition datasets and the PASCAL2007 object detection dataset and compared it to single SVM and common computer vision ensemble-SVM methods. Our algorithm outperforms its competitors and shows a considerable boost on datasets with a limited amount of outliers.\",\n \"Title: Fully Convolutional Crowd Counting On Highly Congested Scenes\\nYear: 2017\\n\\nAbstract: In this paper we advance the state-of-the-art for crowd counting in high density scenes by further exploring the idea of a fully convolutional crowd counting model introduced by (Zhang et al., 2016). Producing an accurate and robust crowd count estimator using computer vision techniques has attracted significant research interest in recent years. Applications for crowd counting systems exist in many diverse areas including city planning, retail, and of course general public safety. Developing a highly generalised counting model that can be deployed in any surveillance scenario with any camera perspective is the key objective for research in this area. Techniques developed in the past have generally performed poorly in highly congested scenes with several thousands of people in frame (Rodriguez et al., 2011). Our approach, influenced by the work of (Zhang et al., 2016), consists of the following contributions: (1) A training set augmentation scheme that minimises redundancy among training samples to improve model generalisation and overall counting performance; (2) a deep, single column, fully convolutional network (FCN) architecture; (3) a multi-scale averaging step during inference. The developed technique can analyse images of any resolution or aspect ratio and achieves state-of-the-art counting performance on the Shanghaitech Part_B and UCF_CC_50 datasets as well as competitive performance on Shanghaitech Part_A.\",\n \"Title: SalGAN: Visual Saliency Prediction with Generative Adversarial Networks.\\nYear: 2017\\n\\nAbstract: We introduce SalGAN, a deep convolutional neural network for visual saliency prediction trained with adversarial examples. The first stage of the network consists of a generator model whose weights are learned by back-propagation computed from a binary cross entropy (BCE) loss over downsampled versions of the saliency maps. The resulting prediction is processed by a discriminator network trained to solve a binary classification task between the saliency maps generated by the generative stage and the ground truth ones. Our experiments show how adversarial training allows reaching state-of-the-art performance across different metrics when combined with a widely-used loss function like BCE. Our results can be reproduced with the source code and trained models available at https://imatge-upc.github. io/saliency-salgan-2017/.\",\n \"Title: A Demonstration of the PATHway System for Technology-enabled Exercise-based Cardiac Rehabilitation.\\nYear: 2016\\n\\nAbstract: We described an invited demonstration to MMHealth'16 of a platform for technology-enabled exercise-based Cardiac Rehabilitation (CR). The demo focuses on one technical aspect of a much broader lifestyle intervention program i.e. real-time estimation of a user's adherence to an exercise programme.\",\n \"Title: A Technology Platform for Enabling Behavioural Change as a \\\"PATHway\\\" Towards Better Self-management of CVD.\\nYear: 2016\\n\\nAbstract: We describe a technology platform developed as part of a novel approach to technology-enabled exercise-based Cardiac Rehabilitation (CR), termed PATHway. We explain the overall concept and explain how technology can facilitate remote participation and better adherence to community-based long-term Phase III CR. The demo will showcase the user experience of interacting with the PATHway system, including navigation and manual data entry, whilst also demonstrating real-time sensing and analysis of exercise movements and automatic adaptation of exercise based on physiological response.\",\n \"Title: Smart Stadium for Smarter Living: Enriching the Fan Experience\\nYear: 2016\\n\\nAbstract: Rapid urbanization has led to more people residing in cities than ever before, and projections estimate that 64% of the global population will be urban by 2050. Cities are beginning to explore Smart City initiatives to reduce expenses and complexities while increasing efficiency and quality of life for its citizens. To achieve this goal, advances in technology and policies are needed together with rethinking traditional solutions to transportation, safety, sustainability, among other priority areas. We propose the use of a Smart Stadium as a 'living laboratory' to identify, deploy and test Internet of Things technologies and Smart City solutions in an environment small enough to practically trial but large enough to evaluate effectiveness and scalability. The Smart Stadium for Smarter Living initiative brings together Arizona State University, Dublin City University, Intel Corporation, Gaelic Athletic Association, Sun Devil Stadium and Croke Park to explore smart environment solutions.\",\n \"Title: Enriching The Fan Experience In A Smart Stadium Using Internet Of Things Technologies\\nYear: 2017\\n\\nAbstract: Rapid urbanization has brought about an influx of people to cities, tipping the scale between urban and rural living. Population predictions estimate that 64% of the global population will reside in cities by 2050. To meet the growing resource needs, improve management, reduce complexities, and eliminate unnecessary costs while enhancing the quality of life of citizens, cities are increasingly exploring open innovation frameworks and smart city initiatives that target priority areas including transportation, sustainability, and security. The size and heterogeneity of urban centers impede progress of technological innovations for smart cities. We propose a Smart Stadium as a living laboratory to balance both size and heterogeneity so that smart city solutions and Internet of Things (IoT) technologies may be deployed and tested within an environment small enough to practically trial but large and diverse enough to evaluate scalability and efficacy. The Smart Stadium for Smart Living initiative brings together multiple institutions and partners including Arizona State University (ASU), Dublin City University (DCU), Intel Corporation, and Gaelic Athletic Association (GAA), to turn ASU's Sun Devil Stadium and Ireland's Croke Park Stadium into twinned smart stadia to investigate IoT and smart city technologies and applications.\",\n \"Title: ResnetCrowd: A residual deep learning architecture for crowd counting, violent behaviour detection and crowd density level classification\\nYear: 2017\\n\\nAbstract: In this paper we propose ResnetCrowd, a deep residual architecture for simultaneous crowd counting, violent behaviour detection and crowd density level classification. To train and evaluate the proposed multi-objective technique, a new 100 image dataset referred to as Multi Task Crowd is constructed. This new dataset is the first computer vision dataset fully annotated for crowd counting, violent behaviour detection and density level classification. Our experiments show that a multi-task approach boosts individual task performance for all tasks and most notably for violent behaviour detection which receives a 9% boost in ROC curve AUC (Area under the curve). The trained ResnetCrowd model is also evaluated on several additional benchmarks highlighting the superior generalisation of crowd analysis models trained for multiple objectives.\",\n \"Title: Automatic Detection of Knee Joints and Quantification of Knee Osteoarthritis Severity using Convolutional Neural Networks.\\nYear: 2017\\n\\nAbstract: This paper introduces a new approach to automatically quantify the severity of knee OA using X-ray images. Automatically quantifying knee OA severity involves two steps: first, automatically localizing the knee joints; next, classifying the localized knee joint images. We introduce a new approach to automatically detect the knee joints using a fully convolutional neural network (FCN). We train convolutional neural networks (CNN) from scratch to automatically quantify the knee OA severity optimizing a weighted ratio of two loss functions: categorical cross-entropy and mean-squared loss. This joint training further improves the overall quantification of knee OA severity, with the added benefit of naturally producing simultaneous multi-class classification and regression outputs. Two public datasets are used to evaluate our approach, the Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis Study (MOST), with extremely promising results that outperform existing approaches.\",\n \"Title: Semantic Indexing of Wearable Camera Images: Kids'Cam Concepts\\nYear: 2016\\n\\nAbstract: In order to provide content-based search on image media, including images and video, they are typically accessed based on manual or automatically assigned concepts or tags, or sometimes based on image-image similarity depending on the use case. While great progress has been made in very recent years in automatic concept detection using machine learning, we are still left with a mis-match between the semantics of the concepts we can automatically detect, and the semantics of the words used in a user's query, for example. In this paper we report on a large collection of images from wearable cameras gathered as part of the Kids'Cam project, which have been both manually annotated from a vocabulary of 83 concepts, and automatically annotated from a vocabulary of 1,000 concepts. This collection allows us to explore issues around how language, in the form of two distinct concept vocabularies or spaces, one manually assigned and thus forming a ground-truth, is used to represent images, in our case taken using wearable cameras. It also allows us to discuss, in general terms, issues around mis-match of concepts in visual media, which derive from language mis-matches. We report the data processing we have completed on this collection and some of our initial experimentation in mapping across the two language vocabularies.\",\n \"Title: MMHealth 2017: Workshop on Multimedia for Personal Health and Health Care.\\nYear: 2018\\n\\nAbstract: The goal of the MMHealth 2017 Workshop on Multimedia for Personal Health and Health Care was to explore the relevance and contribution of multimedia in healthcare and personal health. After a successful debut in Amsterdam in 2016, the second workshop at ACM Multimedia 2017 in Mountain View, California, again attracted more than 30 participants, indicating the relevance that this topic has in the m...\",\n \"Title: MedFit: A Mobile Application for Patients in CVD Recovery.\\nYear: 2017\\n\\nAbstract: The third phase of the recovery from cardiovascular disease (CVD) is an exercise-based rehabilitation programme. However, adherence to an exercise regime is typically not maintained by the patient for a variety of reasons such as lack of time, financial constraints, etc. In order to facilitate patients to perform their exercises from the comfort of their home and at their own convenience, we have developed a mobile application, termed MedFit. It provides access to a tailored suite of exercises along with easy to understand guidance from audio and video instructions. Two types of wearable sensors are utilized to provide motivational feedback. Fitbit, a commercially available activity and fitness tracker, is used to provide in-depth feedback for self-monitoring over longer periods of time (e.g. day, week, month), whereas the Shimmer wireless sensing platform provides the data for near real-time feedback on the quality of the exercises performed. MedFit is a simple and intuitive mobile application designed to provide the motivation and tools for patients to help ensure faster recovery from the trauma caused by CVD. In this paper we describe features available in the MedFit application and the overall motivation behind the project.\",\n \"Title: Saliency Weighted Convolutional Features for Instance Search\\nYear: 2018\\n\\nAbstract: This work explores attention models to weight the contribution of local convolutional representations for the instance search task. We present a retrieval framework based on bags of local convolutional features (BLCF) that benefits from saliency weighting to build an efficient image representation. The use of human visual attention models (saliency) allows significant improvements in retrieval performance without the need to conduct region analysis or spatial verification, and without requiring any feature fine tuning. We investigate the impact of different saliency models, finding that higher performance on saliency benchmarks does not necessarily equate to improved performance when used in instance search tasks. The proposed approach outperforms the state-of-the-art on the challenging INSTRE benchmark by a large margin, and provides similar performance on the Oxford and Paris benchmarks compared to more complex methods that use off-the-shelf representations. Source code is publicly available at https:llgithub.com/imatge-upc/salbow.\",\n \"Title: Understanding packet loss for sound monitoring in a smart stadium IoT testbed.\\nYear: 2017\\n\\nAbstract: The Smart Stadium for Smarter Living project provides an end-to-end testbed for IoT innovation through a collaboration between Croke Park Stadium in Dublin, Ireland and Dublin City University, Intel and Microsoft. This enables practical evaluations of IoT solutions in a controlled environment that is small enough to conduct trials but large enough to prove and challenge the technologies. An evaluation of sound monitoring capabilities during the 2016 sporting finals was used to test the capture, transfer, storage and analysis of decibel level sound monitoring. The purpose of the evaluation was to use existing sound level microphones to measure crowd response to pre-determined events for display on big screens at half-time and to test the end-to-end performance of the testbed. While this is not the specific original purpose of the sound level microphones, it provided a useful test case and produced engaging content for the project. Analysis of the data streams showed significant packet loss during the events and further investigations were conducted to understand where and how this loss occurred. This paper describes the smart stadium testbed configuration using Intel gateways linking with the Azure cloud platform and analyses the performance of the system during the sound monitoring evaluation.\",\n \"Title: Player detection in field sports.\\nYear: 2018\\n\\nAbstract: We describe a method for player detection in field sports with a fixed camera setup based on a new player feature extraction strategy. The proposed method detects players in static images with a sliding window technique. First, we compute a binary edge image and then the detector window is shifted over the edge regions. Given a set of binary edges in a sliding window, we introduce and solve a particular diffusion equation to generate a shape information image. The proposed diffusion to generate a shape information image is the key stage and the main theoretical contribution in our new algorithm. It removes the appearance variations of an object while preserving the shape information. It also enables the use of polar and Fourier transforms in the next stage to achieve scale- and rotation-invariant feature extraction. A support vector machine classifier is used to assign either player or non-player class inside a detector window. We evaluate our approach on three different field hockey datasets. In general, results show that the proposed feature extraction is effective and performs competitive results compared to the state-of-the-art methods.\",\n \"Title: Health Media: From Multimedia Signals to Personal Health Insights.\\nYear: 2018\\n\\nAbstract: In this article, we explore the relevance and contribution of new signals in a broader interpretation of multimedia for personal health. We present how core multimedia research is becoming an important enabler for applications with the potential for significant societal impact.\",\n \"Title: Automatic MOOC Video Classification using Transcript Features and Convolutional Neural Networks.\\nYear: 2017\\n\\nAbstract: The amount of MOOC video materials has grown exponentially in recent years. Therefore, their storage and analysis need to be made as fully automated as possible in order to maintain their management quality. In this work, we present a method for automatic topic classification of MOOC videos using speech transcripts and convolutional neural networks (CNN). Our method works as follows: First, speech recognition is used to generate video transcripts. Then, the transcripts are converted into images using a statistical co-occurrence transformation that we designed. Finally, a CNN is used to produce video category labels for a transcript image input. For our data, we use the Khan Academy on a Stick dataset that contains 2,545 videos, where each video is labeled with one or two of 13 categories. Experiments show that our method is strongly competitive against other methods that are also based on transcript features and supervised learning.\",\n \"Title: Temporal segmentation and recognition of team activities in sports\\nYear: 2018\\n\\nAbstract: A method for temporal segmentation and recognition of team activities in sports, based on a new activity feature extraction, is presented. Given the positions of team players from a plan view of the playground at any given time, we generate a smooth distribution on the whole playground, termed the position distribution of the team. Computing the position distribution for each frame provides a sequence of distributions, which we process to extract motion features for activity recognition. We can classify six different team activities in European handball and eight different team activities in field hockey datasets. The field hockey dataset is a new, large and challenging dataset that is presented for the first time for continuous segmentation of team activities. Our approach is different from other trajectory-based methods. These methods extract activity features using the explicitly defined trajectories, where the players have specific positions. In our work, given the specific positions of the team players at a frame, we construct a position distribution for the team on the whole playground and process the sequence of position distribution images to extract activity features. Extensive evaluation and results show that our approach is effective.\",\n \"Title: A comparison between end-to-end approaches and feature extraction based approaches for Sign Language recognition\\nYear: 2017\\n\\nAbstract: In this paper we use a new image dataset for Irish Sign Language (ISL) and we compare different approaches for recognition. We perform experiments and report comparative accuracy and timing. We perform tests over blurred images and compare results with non-blurred images. For classification, we use end-to-end approaches, such as Convolutional Neural Networks (CNN) and feature based extraction approaches, such as Principal Component Analysis (PCA) followed by different classifiers, e.g. multilayer perceptron (MLP). We obtain a recognition accuracy over 99% for both approaches. In addition, we report different ways to split the training and testing dataset, one being iterative and the other randomly selected.\",\n \"Title: Design and Development of the MedFit App: A Mobile Application for Cardiovascular Disease Rehabilitation.\\nYear: 2017\\n\\nAbstract: Rehabilitation from cardiovascular disease (CVD) usually requires lifestyle changes, especially an increase in exercise and physical activity. However, uptake and adherence to exercise is low for community-based programmes. We propose a mobile application that allows users to choose the type of exercise and compete it at a convenient time in the comfort of their own home. Grounded in a behaviour change framework, the application provides feedback and encouragement to continue exercising and to improve on previous results. The application also utilizes wearable wireless technologies in order to provide highly personalized feedback. The application can accurately detect if a specific exercise is being done, and count the associated number of repetitions utilizing accelerometer or gyroscope signals Machine learning models are employed to recognize individual local muscular endurance (LME) exercises, achieving overall accuracy of more than 98%. This technology allows providing a near real-time personalized feedback which mimics the feedback that the user might expect from an instructor. This is provided to motivate users to continue the recovery process.\",\n \"Title: HealthMedia 2018: Third International Workshop on Multimedia for Personal Health and Health Care.\\nYear: 2018\\n\\nAbstract: Research in multimedia and health is driven by the current technological advancements in sensors and personalized healthcare. There is an increasing amount of work that shows how core multimedia research is becoming an important enabler for solutions with applications and relevance for the societal questions of health. This workshop brings together researchers from diverse topics such as multimedia, pervasive health, lifelogging, accessibility, HCI, but also health, medicine, and psychology to address challenges and opportunities of multimedia in and for health.\",\n \"Title: Demonstration of an Open Source Framework for Qualitative Evaluation of CBIR Systems.\\nYear: 2018\\n\\nAbstract: Evaluating image retrieval systems in a quantitative way, for example by computing measures like mean average precision, allows for objective comparisons with a ground-truth. However, in cases where ground-truth is not available, the only alternative is to collect feedback from a user. Thus, qualitative assessments become important to better understand how the system works. Visualizing the results could be, in some scenarios, the only way to evaluate the results obtained and also the only opportunity to identify that a system is failing. This necessitates developing a User Interface (UI) for a Content Based Image Retrieval (CBIR) system that allows visualization of results and improvement via capturing user relevance feedback. A well-designed UI facilitates understanding of the performance of the system, both in cases where it works well and perhaps more importantly those which highlight the need for improvement. Our open-source system implements three components to facilitate researchers to quickly develop these capabilities for their retrieval engine. We present: a web-based user interface to visualize retrieval results and collect user annotations; a server that simplifies connection with any underlying CBIR system; and a server that manages the search engine data. The software itself is described in a separate submission to the ACM MM Open Source Software Competition.\",\n \"Title: A Deep Residual Architecture For Skin Lesion Segmentation\\nYear: 2018\\n\\nAbstract: In this paper, we propose an automatic approach to skin lesion region segmentation based on a deep learning architecture with multi-scale residual connections. The architecture of the proposed model is based on UNet [22] with residual connections to maximise the learning capability and performance of the network. The information lost in the encoder stages due to the max-pooling layer at each level is preserved through the multi-scale residual connections. To corroborate the efficacy of the proposed model, extensive experiments are conducted on the ISIC 2017 challenge dataset without using any external dermatologic image set. An extensive comparative analysis is presented with contemporary methodologies to highlight the promising performance of the proposed methodology.\",\n \"Title: Automatic Estimation of Enjoyment Levels during Cardiac Rehabilitation Exercise.\\nYear: 2018\\n\\nAbstract: Cardiovascular disease (CVD) is the leading cause of premature death and disability in Europe and worldwide. Effective Cardiac Rehabilitation (CR) can significantly improve mortality and morbidity rates, leading to longer independent living and a reduced use of health care resources. However, adherence to such an exercise programme is generally low for a variety of reasons such as lack of time and how enjoyable the CR programme is. In this work, we proposed a method for automatic enjoyment estimation during an exercise which could be used by a clinician to identify when a patient is not enjoying the exercise and therefore at risk of early dropout. In order to evaluate the proposed method, a database was captured where participants perform various of CR exercises. Three set of facial features were extracted and were evaluated using seven different classifiers. The proposed method achieved 49% average accuracy in predicting five different enjoyment level on the newly collected database.\",\n \"Title: A Residual Encoder-Decoder Network for Semantic Segmentation in Autonomous Driving Scenarios.\\nYear: 2018\\n\\nAbstract: In this paper, we propose an encoder-decoder based deep convolutional network for semantic segmentation in autonomous driving scenarios. The architecture of the proposed model is based on VGG16 [1]. Residual learning is introduced to preserve the context while decreasing the size of feature maps between the stacks of convolutional layers. Also, the resolution is preserved through shortcuts from the encoder stage to the decoder stage. Experiments are conducted on popular benchmark datasets CamVid and CityScapes to demonstrate the efficacy of the proposed model. The experiments are corroborated with comparative analysis with popular encoder-decoder networks such as SegNet and Enet architectures demonstrating that the proposed approach outperforms existing methods despite having fewer trainable parameters.\",\n \"Title: Exploring the Impact of Training Data Bias on Automatic Generation of Video Captions.\\nYear: 2019\\n\\nAbstract: A major issue in machine learning is availability of training data. While this historically referred to the availability of a sufficient volume of training data, recently this has shifted to the availability of sufficient unbiased training data. In this paper we focus on the effect of training data bias on an emerging multimedia application, the automatic captioning of short video clips. We use subsets of the same training data to generate different models for video captioning using the same machine learning technique and we evaluate the performances of different training data subsets using a well-known video caption benchmark, TRECVid. We train using the MSR-VTT video-caption pairs and we prune this to reduce and make the set of captions describing a video more homogeneously similar, or more diverse, or we prune randomly. We then assess the effectiveness of caption-generating trained with these variations using automatic metrics as well as direct assessment by human assessors. Our findings are preliminary and show that randomly pruning captions from the training data yields the worst performance and that pruning to make the data more homogeneous, or diverse, does improve performance slightly when compared to random. Our work points to the need for more training data, both more video clips but, more importantly, more captions for those videos.\",\n \"Title: Towards An \\\"Ethics By Design\\\" Methodology For Ai Research Projects\\nYear: 2018\\n\\nAbstract: Addressing ethical issues arising from AI research, and by extension from most areas of Data Science, is a core challenge in both the academic and industry worlds. The nature of research and the specific set of technical skills involved imply that AI and Data Science researchers are not equipped to identify and anticipate such issues arising, or to establish solutions at the time a specific research project is being designed. In this paper, we discuss the need for a methodology for ethical research design that involves a broader set of skills from the start of the project. We specifically identify, from the relevant literature, a set of requirements that we argue to be needed for such a methodology. We then explore two case studies where such ethical considerations have been explored in conjunction with the development of specific research projects, in order to validate those assumptions and generalise them into a set of principles guiding an \\\"Ethics by Design\\\" method for conducting AI and Data Science research.\",\n \"Title: Abnormal crowd behavior detection using novel optical flow-based features\\nYear: 2017\\n\\nAbstract: In this paper, we propose a novel optical flow based features for abnormal crowd behaviour detection. The proposed feature is mainly based on the angle difference computed between the optical flow vectors in the current frame and in the previous frame at each pixel location. The angle difference information is also combined with the optical flow magnitude to produce new, effective and direction invariant event features. A one-class SVM is utilized to learn normal crowd behavior. If a test sample deviates significantly from the normal behavior, it is detected as abnormal crowd behavior. Although there are many optical flow based features for crowd behaviour analysis, this is the first time the angle difference between optical flow vectors in the current frame and in the previous frame is considered as a anomaly feature. Evaluations on UMN and PETS2009 datasets show that the proposed method performs competitive results compared to the state-of-the-art methods.\",\n \"Title: Action localization in video using a graph-based feature representation\\nYear: 2017\\n\\nAbstract: We propose a new framework for human action localization in video sequences. The option to not only detect but also localize actions in surveillance video is crucial to improving system's ability to manage high volumes of CCTV. In the approach, the action localization task is formulated the maximum-path finding problem in the directed spatio-temporal video-graph. The graph is constructed on the top of frame and temporal-based low-level features. To localize actions in the video-graph, we apply a maximum-path algorithm to find the path in the graph that is considered to be the localized action in the video. The proposed approach achieves competitive performance with the J-HMDB and the UCF-Sports dataset.\",\n \"Title: A Text Recognition and Retrieval System for e-Business Image Management.\\nYear: 2018\\n\\nAbstract: The on-going growth of e-business has resulted in companies having to manage an ever increasing number of product, packaging and promotional images. Systems for indexing and retrieving such images are required in order to ensure image libraries can be managed and fully exploited as valuable business resources. In this paper, we explore the power of text recognition for e-business image management and propose an innovative system based on photo OCR. Photo OCR has been actively studied for scene text recognition but has not been exploited for e-business digital image management. Besides the well known difficulties in scene text recognition such as various size, location, orientation in text and cluttered background, e-business images typically feature text with extremely diverse fonts, and the characters are often artistically modified in shape, colour and arrangement. To address these challenges, our system takes advantage of the combinatorial power of deep neural networks and MSER processing. The cosine distance and n-gram vectors are used during retrieval for matching detected text to queries to provide tolerance to the inevitable transcription errors in text recognition. To evaluate our proposed system, we prepared a novel dataset designed specifically to reflect the challenges associated with text in e-business images. We compared our system with two other approaches for scene text recognition, and the results show our system outperforms other state-of-the-art on the new challenging dataset. Our system demonstrates that recognizing text embedded in images can be hugely beneficial for digital asset management.\",\n \"Title: Educational video classification by using a transcript to image transform and supervised learning\\nYear: 2017\\n\\nAbstract: In this work, we present a method for automatic topic classification of educational videos using a speech transcript transform. Our method works as follows: First, speech recognition is used to generate video transcripts. Then, the transcripts are converted into images using a statistical cooccurrence transformation that we designed. Finally, a classifier is used to produce video category labels for a transcript image input. For our classifiers, we report results using a convolutional neural network (CNN) and a principal component analysis (PCA) model. In order to evaluate our method, we used the Khan Academy on a Stick dataset that contains 2,545 videos, where each video is labeled with one or two of 13 categories. Experiments show that our method is effective and strongly competitive against other supervised learning-based methods.\",\n \"Title: A novel shape descriptor based on salient keypoints detection for binary image matching and retrieval.\\nYear: 2018\\n\\nAbstract: We introduce a shape descriptor that extracts keypoints from binary images and automatically detects the salient ones among them. The proposed descriptor operates as follows: First, the contours of the image are detected and an image transformation is used to generate background information. Next, pixels of the transformed image that have specific characteristics in their local areas are used to extract keypoints. Afterwards, the most salient keypoints are automatically detected by filtering out redundant and sensitive ones. Finally, a feature vector is calculated for each keypoint by using the distribution of contour points in its local area. The proposed descriptor is evaluated using public datasets of silhouette images, handwritten math expressions, hand-drawn diagram sketches, and noisy scanned logos. Experimental results show that the proposed descriptor compares strongly against state of the art methods, and that it is reliable when applied on challenging images such as fluctuated handwriting and noisy scanned images. Furthermore, we integrate our descriptor in a content-based document image retrieval system using sketch queries as a step for query and candidate occurrence matching, and we show that it leads to a significant boost in retrieval performances.\",\n \"Title: Scanpath and saliency prediction on 360 degree images.\\nYear: 2018\\n\\nAbstract: We introduce deep neural networks for scanpath and saliency prediction trained on 360-degree images. The scanpath prediction model called SaltiNet is based on a temporal-aware novel representation of saliency information named the saliency volume. The first part of the network consists of a model trained to generate saliency volumes, whose parameters are fit by back-propagation using a binary cross entropy (BCE) loss over downsampled versions of the saliency volumes. Sampling strategies over these volumes are used to generate scanpaths over the 360-degree images. Our experiments show the advantages of using saliency volumes, and how they can be used for related tasks. We also show how a similar architecture achieves state-of-the-art performance for the related task of saliency map prediction. Our source code and trained models available at https://github.com/massens/saliency-360salient-2017.\",\n \"Title: SaltiNet: Scan-path Prediction on 360 Degree Images using Saliency Volumes.\\nYear: 2017\\n\\nAbstract: We introduce SaltiNet, a deep neural network for scan-path prediction trained on 360-degree images. The model is based on a temporal-aware novel representation of saliency information named the saliency volume. The first part of the network consists of a model trained to generate saliency volumes, whose parameters are fit by back-propagation computed from a binary cross entropy (BCE) loss over downsampled versions of the saliency volumes. Sampling strategies over these volumes are used to generate scan-paths over the 360-degree images. Our experiments show the advantages of using saliency volumes, and how they can be used for related tasks. Our source code and trained models available at https://github.com/massens/saliency-360salient-2017.\",\n \"Title: A Low-Cost Smart Sensor Network for Catchment Monitoring.\\nYear: 2019\\n\\nAbstract: Understanding hydrological processes in large, open areas, such as catchments, and further modelling these processes are still open research questions. The system proposed in this work provides an automatic end-to-end pipeline from data collection to information extraction that can potentially assist hydrologists to better understand the hydrological processes using a data-driven approach. In this work, the performance of a low-cost off-the-shelf self contained sensor unit, which was originally designed and used to monitor liquid levels, such as AdBlue, fuel, lubricants etc., in a sealed tank environment, is first examined. This process validates that the sensor does provide accurate water level information for open water level monitoring tasks. Utilising the dataset collected from eight sensor units, an end-to-end pipeline of automating the data collection, data processing and information extraction processes is proposed. Within the pipeline, a data-driven anomaly detection method that automatically extracts rapid changes in measurement trends at a catchment scale. The lag-time of the test site (Dodder catchment Dublin, Ireland) is also analyzed. Subsequently, the water level response in the catchment due to storm events during the 27 month deployment period is illustrated. To support reproducible and collaborative research, the collected dataset and the source code of this work will be publicly available for research purposes.\",\n \"Title: An evaluation of a 3D multimodal marker-less motion analysis system\\nYear: 2019\\n\\nAbstract: Motion analysis is a technique used by clinicians (among many others) that quantifies human movement by using camera-based systems. Marker-based motion analysis systems have been used across a variety of application domains, from Interactive 3D Tele-Immersion (i3DTI) environments to the diagnosis of neuromuscular and musculoskeletal diseases. Although such analysis is performed in several laboratories in many countries, numerous issues exist: (1) the high cost of precise motion capture systems; (2) scarcity of qualified personnel to operate them; (3) expertise required to interpret their results; (4) space requirements to install and store these systems; (5) complexity in terms of measurement protocol required for such systems; (6) limited availability; (7) and in some situations the use of markers means they are unsuitability for certain clinical use cases (e.g. for patients recovering from orthopaedic surgery). In this paper, we present, from a system perspective, an alternative, cheaper, and more accessible system for motion analysis. The ultimate aim is to use the output of this multimodal marker-less system as part of an immersive multimedia gait re-education tool. In real-time, it will advise the user on their gait performance (as well as potentially providing accurate clinical data to clinicians). With the initial focus on the capture system, we have developed and evaluated a novel multimodal system which integrates Multiple Microsoft Kinects (which employ RGB-D cameras) with multiple Shimmer Inertial Measurement Unit (IMU) sensors. We have compared this system with the VICON system (the gold standard in motion capture). Our marker-less motion capture system combines data from 4 skeletons generating 3D and complete 360 degrees in view skeleton. The system combines unit quaternions from each Kinect joint with quaternions from 4 inertial measurement units to promote integration. We used our system to measure 3D points of 12 joints from the Kinect fused skeleton and flexion-extension angles of the knee and hip in a walking trial in 8 participants with 8--10 trials per participant. The analysis found component similarity of 0.97 for knee angles and 0.98 for hip angles. These results show that our system, through combination of Multi Kinect system and Shimmer IMUs, offers a cheaper, sufficiently accurate and more accessible human motion analysis system.\",\n \"Title: Unsupervised label noise modeling and loss correction\\nYear: 2019\\n\\nAbstract: Despite being robust to small amounts of label noise, convolutional neural networks trained with stochastic gradient methods have been shown to easily fit random labels. When there are a mixture of correct and mislabelled targets, networks tend to fit the former before the latter. This suggests using a suitable two-component mixture model as an unsupervised generative model of sample loss values during training to allow online estimation of the probability that a sample is mislabelled. Specifically, we propose a beta mixture to estimate this probability and correct the loss by relying on the network prediction (the so-called bootstrapping loss). We further adapt mixup augmentation to drive our approach a step further. Experiments on CIFAR-10/100 and TinyImageNet demonstrate a robustness to label noise that substantially outperforms recent state-of-the-art. Source code is available at this https URL\",\n \"Title: On guiding video object segmentation\\nYear: 2019\\n\\nAbstract: This paper presents a novel approach for segmenting moving objects in unconstrained environments using guided convolutional neural networks. This guiding process relies on foreground masks from independent algorithms (i.e. state-of-the-art algorithms) to implement an attention mechanism that incorporates the spatial location of foreground and background to compute their separated representations. Our approach initially extracts two kinds of features for each frame using colour and optical flow information. Such features are combined following a multiplicative scheme to benefit from their complementarity. These unified colour and motion features are later processed to obtain the separated foreground and background representations. Then, both independent representations are concatenated and decoded to perform foreground segmentation. Experiments conducted on the challenging DAVIS 2016 dataset demonstrate that our guided representations not only outperform non-guided, but also recent and top-performing video object segmentation algorithms.\",\n \"Title: Assessing Knee OA Severity with CNN attention-based end-to-end architectures.\\nYear: 2019\\n\\nAbstract: This work proposes a novel end-to-end convolutional neural network (CNN) architecture to automatically quantify the severity of knee osteoarthritis (OA) using X-Ray images, which incorporates trainable attention modules acting as unsupervised fine-grained detectors of the region of interest (ROI). The proposed attention modules can be applied at different levels and scales across any CNN pipeline helping the network to learn relevant attention patterns over the most informative parts of the image at different resolutions. We test the proposed attention mechanism on existing state-of-the-art CNN architectures as our base models, achieving promising results on the benchmark knee OA datasets from the osteoarthritis initiative (OAI) and multicenter osteoarthritis study (MOST).\",\n \"Title: Open-Source: Attention-Based Neural Networks For Chroma Intra Prediction In Video Coding\\nYear: 2021\\n\\nAbstract: Neural networks can be successfully used to improve several modules of advanced video coding schemes. In particular, compression of colour components was shown to greatly benefit from usage of machine learning models, thanks to the design of appropriate attention-based architectures that allow the prediction to exploit specific samples in the reference region. However, such architectures tend to b...\",\n \"Title: Guest Editorial Special Section on IEEE ICME 2020\\nYear: 2021\\n\\nAbstract: This special section contains extended versions of papers presented at the IEEE International Conference on Multimedia & Expo (ICME) in London, July 2020. The invitations to contribute to the special section were based on the quality of the conference paper and its relevance to the aims and scope of the journal. Each submitted manuscript was reviewed by at least three anonymous reviewers. After a rigorous review process, three papers were accepted. Two of them present new developments in immersive media, while the third deals with the problem of efficiently encoding a deep neural network.\",\n \"Title: How Important is Importance Sampling for Deep Budgeted Training?\\nYear: 2021\\n\\nAbstract: Long iterative training processes for Deep Neural Networks (DNNs) are commonly required to achieve state-of-the-art performance in many computer vision tasks. Importance sampling approaches might play a key role in budgeted training regimes, i.e. when limiting the number of training iterations. These approaches aim at dynamically estimating the importance of each sample to focus on the most relevant and speed up convergence. This work explores this paradigm and how a budget constraint interacts with importance sampling approaches and data augmentation techniques. We show that under budget restrictions, importance sampling approaches do not provide a consistent improvement over uniform sampling. We suggest that, given a specific budget, the best course of action is to disregard the importance and introduce adequate data augmentation; e.g. when reducing the budget to a 30% in CIFAR-10/100, RICAP data augmentation maintains accuracy, while importance sampling does not. We conclude from our work that DNNs under budget restrictions benefit greatly from variety in the training set and that finding the right samples to train on is not the most effective strategy when balancing high performance with low computational requirements. Source code available at https://git.io/JKHa3 .\",\n \"Title: Rethinking 360° Image Visual Attention Modelling with Unsupervised Learning.\\nYear: 2021\\n\\nAbstract: Despite the success of self-supervised representation learning on planar data, to date it has not been studied on 360deg images. In this paper, we extend recent advances in contrastive learning to learn latent representations that are sufficiently invariant to be highly effective for spherical saliency prediction as a downstream task. We argue that omni-directional images are particularly suited to such an approach due to the geometry of the data domain. To verify this hypothesis, we design an unsupervised framework that effectively maximizes the mutual information between the different views from both the equator and the poles. We show that the decoder is able to learn good quality saliency distributions from the encoder embeddings. Our model compares favorably with fully-supervised learning methods on the Salient360!, VR-EyeTracking and Sitzman datasets. This performance is achieved using an encoder that is trained in a completely unsupervised way and a relatively lightweight supervised decoder (3.8 X fewer parameters in the case of the ResNet50 encoder). We believe that this combination of supervised and unsupervised learning is an important step toward flexible formulations of human visual attention.\",\n \"Title: UrbanAccess: Query Driven Urban Analytics Platform for Detecting Complex Accessibility Event Patterns using Tactile Surfaces\\nYear: 2021\\n\\nAbstract: BSTRACTThe smart city concept has now become one of the key enablers in urban city management. The adoption and permeation of ICT and AI-driven techniques have enabled the authorities to resolve poor urban planning issues with improved delivery of citizen services. Major urban problem is addressing the accessibility issue across cities road crossing and facilitating visually impaired people via well-defined infrastructure. The research presented in this paper emphasized urban analytics that studies the road crossings and challenges one faces when accessing the footpaths of a city using the Tactile surfaces. This work demonstrates a distributed event analytics platform- GNOSIS to detect complex accessibility event patterns. GNOSIS ingest video data streams from cities infrastructure such as CCTV and detect tactile surface event patterns using an ensemble of deep learning models using a declarative query language. The work analyzes mainly three types of tactile surface - Blister, Cycleway and Directional, collected from different cities in Ireland using crowd-sourcing techniques. GNOSIS makes decisions in real-time based on the type of tactile surface, colour and the making pattern.\",\n \"Title: Simple baselines can fool 360 degrees saliency metrics\\nYear: 2021\\n\\nAbstract: Evaluating a model's capacity to predict human fixations in 360 degrees scenes is a challenging task. 360 degrees saliency requires different assumptions compared to 2D as a result of the way the saliency maps are collected and pre-processed to account for the difference in statistical bias (Equator vs Center bias). However, the same classical metrics from the 2D saliency literature are typically used to evaluate 360 degrees models. In this paper, we show that a simple constant predictor, i.e. the average map across Salient360 and Sitzman training sets can fool existing metrics and achieve results on par with specialized models. Thus, we propose a new probabilistic metric based on the independent Bernoullis assumption that is more suited to the 360 degrees saliency task.\",\n \"Title: BERTHA: Video Captioning Evaluation Via Transfer-Learned Human Assessment.\\nYear: 2022\\n\\nAbstract: Evaluating video captioning systems is a challenging task as there are multiple factors to consider; for instance: the fluency of the caption, multiple actions happening in a single scene, and the human bias of what is considered important. Most metrics try to measure how similar the system generated captions are to a single or a set of human-annotated captions. This paper presents a new method based on a deep learning model to evaluate these systems. The model is based on BERT, which is a language model that has been shown to work well in multiple NLP tasks. The aim is for the model to learn to perform an evaluation similar to that of a human. To do so, we use a dataset that contains human evaluations of system generated captions. The dataset consists of the human judgments of the captions produce by the system participating in various years of the TRECVid video to text task. These annotations will be made publicly available. BERTHA obtain favourable results, outperforming the commonly used metrics in some setups.\",\n \"Title: On the Use of 3D CNNs for Video Saliency Modeling\\nYear: 2020\\n\\nAbstract: There has been emerging interest recently in three dimensional (3D) convolutional neural networks (CNNs) as a powerful tool to encode spatiotemporal representations in videos, by adding a third temporal dimension to preexisting 2D CNNs. In this chapter, we discuss the effectiveness of using 3D convolutions to capture the important motion features in the context of video saliency prediction. The method filters the spatio-temporal features across multiple adjacent frames. This cubic convolution could be effectively applied on a dense sequence of frames propagating the previous frames' information into the current, reflecting processing mechanisms of the human visual system for better saliency prediction. We extensively evaluate the model performance compared to the state-of-the-art video saliency models on both 2D and 360 degrees videos. The architecture can efficiently learn expressive spatio-temporal representations and produce high quality video saliency maps on three large-scale 2D datasets, DHF1K, UCF-SPORTS and DAVIS. Investigations on the 360 degrees Salient360! and datasets show how the approach can generalise.\",\n \"Title: Domain Randomization for Object Counting.\\nYear: 2021\\n\\nAbstract: Recently, the use of synthetic datasets based on game engines has been shown to improve the performance of several tasks in computer vision. However, these datasets are typically only appropriate for the specific domains depicted in computer games, such as urban scenes involving vehicles and people. In this paper, we present an approach to generate synthetic datasets for object counting for any domain without the need for photo-realistic techniques manually generated by expensive teams of 3D artists. We introduce a domain randomization approach for object counting based on synthetic datasets that are quick and inexpensive to generate. We deliberately avoid photorealism and drastically increase the variability of the dataset, producing images with random textures and 3D transformations, which improves generalization. Experiments show that our method facilitates good performance on various real word object counting datasets for multiple domains: people, vehicles, penguins, and fruit. The source code is available at: https://github.com/enric1994/dr4oc\",\n \"Title: Synthetic Data for Unsupervised Polyp Segmentation.\\nYear: 2021\\n\\nAbstract: Deep learning has shown excellent performance in analysing medical images. However, datasets are difficult to obtain due privacy issues, standardization problems, and lack of annotations. We address these problems by producing realistic synthetic images using a combination of 3D technologies and generative adversarial networks. We use zero annotations from medical professionals in our pipeline. Our fully unsupervised method achieves promising results on five real polyp segmentation datasets. As a part of this study we release Synth-Colon, an entirely synthetic dataset that includes 20000 realistic colon images and additional details about depth and 3D geometry: https://enric1994.github.io/synth-colon\",\n \"Title: Unsupervised domain adaptation and super resolution on drone images for autonomous dry herbage biomass estimation\\nYear: 2022\\n\\nAbstract: Herbage mass yield and composition estimation is an important tool for dairy farmers to ensure an adequate supply of high quality herbage for grazing and subsequently milk production. By accurately estimating herbage mass and composition, targeted nitrogen fertiliser application strategies can be deployed to improve localised regions in a herbage field, effectively reducing the negative impacts of over-fertilization on biodiversity and the environment. In this context, deep learning algorithms offer a tempting alternative to the usual means of sward composition estimation, which involves the destructive process of cutting a sample from the herbage field and sorting by hand all plant species in the herbage. The process is labour intensive and time consuming and so not utilised by farmers. Deep learning has been successfully applied in this context on images collected by high-resolution cameras on the ground. Moving the deep learning solution to drone imaging, however, has the potential to further improve the herbage mass yield and composition estimation task by extending the ground-level estimation to the large surfaces occupied by fields/paddocks. Drone images come at the cost of lower resolution views of the fields taken from a high altitude and requires further herbage ground-truth collection from the large surfaces covered by drone images. This paper proposes to transfer knowledge learned on ground-level images to raw drone images in an unsupervised manner. To do so, we use unpaired image style translation to enhance the resolution of drone images by a factor of eight and modify them to appear closer to their ground-level counterparts. We then use the enhanced drone images to train a semi-supervised algorithm that uses ground-truthed, ground-level images as the labelled data together with a large amount of unlabeled drone images. We validate our results on a small held-out drone image test set to show the validity of our approach, which opens the way for automated dry herbage biomass monitoring www.github.com/PaulAlbert31/Clover_SSL.\",\n \"Title: Attention-based Stylisation for Exemplar Image Colourisation\\nYear: 2021\\n\\nAbstract: Exemplar-based colourisation aims to add plausible colours to a grayscale image using the guidance of a colour reference image. Most existing methods tackle the task as a style transfer problem, using a convolutional neural network (CNN) to obtain deep representations of the content of both inputs. Stylised outputs are then obtained by computing similarities between both feature representations in...\",\n \"Title: Embedding Contrastive Unsupervised Features to Cluster In- And Out-of-Distribution Noise in Corrupted Image Datasets.\\nYear: 2022\\n\\nAbstract: Using search engines for web image retrieval is a tempting alternative to manual curation when creating an image dataset, but their main drawback remains the proportion of incorrect (noisy) samples retrieved. These noisy samples have been evidenced by previous works to be a mixture of in-distribution (ID) samples, assigned to the incorrect category but presenting similar visual semantics to other classes in the dataset, and out-of-distribution (OOD) images, which share no semantic correlation with any category from the dataset. The latter are, in practice, the dominant type of noisy images retrieved. To tackle this noise duality, we propose a two stage algorithm starting with a detection step where we use unsupervised contrastive feature learning to represent images in a feature space. We find that the alignment and uniformity principles of contrastive learning allow OOD samples to be linearly separated from ID samples on the unit hypersphere. We then spectrally embed the unsupervised representations using a fixed neighborhood size and apply an outlier sensitive clustering at the class level to detect the clean and OOD clusters as well as ID noisy outliers. We finally train a noise robust neural network that corrects ID noise to the correct category and utilizes OOD samples in a guided contrastive objective, clustering them to improve low-level features. Our algorithm improves the state-of-the-art results on synthetic noise image datasets as well as real-world web-crawled data. Our work is fully reproducible github.com/PaulAlbert31/SNCF.\",\n \"Title: An Evaluation of 360° Video and Audio Quality in an Artistic-Oriented Platform\\nYear: 2022\\n\\nAbstract: Consuming immersive content over a browser is possible due to libraries such as WebGL, WebXR and Three.js. 360° videos, however, are very large in size, and high definition content can cause buffering events even in environments with high bandwidth. Immersiveness is further achieved in 360° content delivery with the addition of ambisonic audio, which indicates the source of sound, according to head tracking of users, in the 3-D space. In situations where video quality needs to be reduced due to network constraints, ambisonics can help increase user-perceived quality. This paper introduces a study of user experience with 24 participants located in various countries considering multiple quality levels of audio and video. An artistic-oriented platform for opera delivery is also described, in the context of the European Horizon 2020 TRACTION project.\",\n \"Title: Incorporating Spatio-Temporal Information in Frustum-ConvNet for Improved 3D Object Detection in Instrumented Vehicles\\nYear: 2022\\n\\nAbstract: Environmental perception is a key task for autonomous vehicles to ensure intelligent planning and safe decision-making. Most current state-of-the-art perceptual methods in vehicles, and in particular for 3D object detection, are based on a single-frame reference. However, these methods do not effectively utilise temporal information associated with the objects or the scene from the input data sequences. The work presented in this paper corroborates the use of spatial and temporal information through multi-frame, lidar, point cloud data to leverage spatio-temporal contextual information and improve the accuracy of 3D object detection. The study also gathers more insights into the effect of inducing temporal information into a network and the overall performance of the deep learning model. We consider the Frustum-ConvNet architecture as the baseline model and propose methods to incorporate spatio-temporal information using convolutional-LSTMs to detect the 3D object detection using lidar data. We also propose to employ an attention mechanism with temporal encoding to stimulate the model to focus on salient feature points within the region proposals. The results from this study shows the inclusion of temporal information considerably improves the true positive metric specifically the orientation error of the 3D bounding box from 0.819 to 0.784 and 0.294 to 0.111 for cars and pedestrian classes respectively on the customized subset of nuScenes training dataset. The overall nuScenes detection score (NDS) is improved from 0.822 to 0.837 compared to the baseline.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":200,"string":"200"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":78,"string":"78"}}},{"rowIdx":79,"cells":{"question_id":{"kind":"string","value":"Robert Shorten"},"question":{"kind":"string","value":"Generate an abstract for the title \"Pricing Vehicle Sharing with Proximity Information.\" using the following items: vehicle sharing, pricing scheme, distance-based pricing, optimal spread, drop-off positions."},"answer":{"kind":"string","value":"For vehicle sharing schemes, where drop-off positions are not fixed, we propose a pricing scheme, where the price depends in part on the distance between where a vehicle is being dropped off and where the closest shared vehicle is parked. Under certain restrictive assumptions, we show that this pricing leads to a socially optimal spread of the vehicles within a region."},"correct_answer":{"kind":"string","value":"For vehicle sharing schemes, where drop-off positions are not fixed, we propose a pricing scheme, where the price depends in part on the distance between where a vehicle is being dropped off and where the closest shared vehicle is parked. Under certain restrictive assumptions, we show that this pricing leads to a socially optimal spread of the vehicles within a region."},"documents":{"kind":"list like","value":["Title: A positive systems model of TCP-like congestion control: asymptotic results\nYear: 2006\n\nAbstract: We study communication networks that employ drop-tail queueing and Additive-Increase Multiplicative-Decrease (AIMD) congestion control algorithms. It is shown that the theory of nonnegative matrices may be employed to model such networks. In particular, important network properties, such as: 1) fairness; 2) rate of convergence; and 3) throughput, can be characterized by certain nonnegative matrices. We demonstrate that these results can be used to develop tools for analyzing the behavior of AIMD communication networks. The accuracy of the models is demonstrated by several NS studies.","Title: Trading link utilization for queueing delays: An adaptive approach\nYear: 2010\n\nAbstract: Understanding the relationship between queueing delays and link utilization for general traffic conditions is an important open problem in networking research. Difficulties in understanding this relationship stem from the fact that it depends on the complex nature of arriving traffic and the problems associated with modelling such traffic. Existing AQM schemes achieve a ''low delay'' and ''high utilization'' by responding early to congestion without considering the exact relationship between delay and utilization. However, in the context of exploiting the delay/utilization tradeoff, the optimal choice of a queueing scheme's control parameter depends on the cost associated with the relative importance of queueing delay and utilization. The optimal choice of control parameter is the one that maximizes a benefit that can be defined as the difference between utilization and cost associated with queuing delay. We present two practical algorithms, Optimal Drop-Tail (ODT) and Optimal BLUE (OB), that are designed with a common performance goal: namely, maximizing this benefit. Their novelty lies in fact that they maximize the benefit in an online manner, without requiring knowledge of the traffic conditions, specific delay-utilization models, nor do they require complex parameter estimation. Packet level ns2 simulations are given to demonstrate the efficacy of the proposed algorithms and the framework in which they are designed.","Title: Preservation of piecewise-linear Lyapunov function under Padé discretization\nYear: 2011\n\nAbstract: In this paper we show that certain piecewise-linear Lyapunov functions are preserved for LTI systems under Padé approximations. In particular, we present a simple method to find a piecewise-linear Lyapunov function that is so preserved under the Padé discretization of any order and sampling time. This result may be of interest in the discretisation of switched linear systems for both simulation and control design.","Title: Fully decentralized emulation of best-effort and processor sharing queues\nYear: 2008\n\nAbstract: Control of large distributed cloud-based services is a challenging problem. The Distributed Rate Limiting (DRL) paradigm was recently proposed as a mechanism for tackling this problem. The heuristic nature of existing DRL solutions makes their behavior unpredictable and analytically untractable. In this paper we treat the DRL problem in a mathematical framework and propose two novel DRL algorithms that exhibit good and predictable performance. The first algorithm Cloud Control with Constant Probabilities (C3P) solves the DRL problem in best effort environments, emulating the behavior of a single best-effort queue in a fully distributed manner. The second problem we approach is the DRL in processor sharing environments. Our algorithm, Distributed Deficit Round Robin (D2R2), parameterized by parameter α, converges to a state that is, at most, O(1/α) away from the exact emulation of centralized processor sharing queue. The convergence and stability properties are fully analyzed for both C3P and D2R2. Analytical results are validated empirically through a number of representative packet level simulations. The closed-form nature of our results allows simple design rules which, together with extremely low communication overhead, makes the presented algorithms practical and easy to deploy.","Title: Quadratic And Copositive Lyapunov Functions And The Stability Of Positive Switched Linear Systems\nYear: 2007\n\nAbstract: We present some new results concerning the stability of positive switched linear systems. In particular, we present a necessary and suffcient condition for the existence of copositive linear Lyapunov functions for switched systems with two constituent linear time-invariant (LTI) systems. We also extend some recent results on quadratic stability for positive switched linear systems.","Title: Nonlinear AIMD Congestion Control and Contraction Mappings\nYear: 2007\n\nAbstract: This papers analyzes a class of nonlinear additive-increase multiplicative-decrease (AIMD) protocols that are widely deployed in communication networks. It is demonstrated that the use of these protocols guarantees that the system has a unique stable outcome to which it converges geometrically under all starting points. The development is based on a contraction argument and the derivation of explicit bounds on the contraction coefficient of corresponding operators in terms of the network parameters. In particular, bounds on the corresponding rate of convergence are obtained, improving upon known bounds for standard (linear) AIMD networks.","Title: A Nonconservative LMI Condition for Stability of Switched Systems With Guaranteed Dwell Time.\nYear: 2012\n\nAbstract: Ensuring stability of switched linear systems with a guaranteed dwell time is an important problem in control systems. Several methods have been proposed in the literature to address this problem, but unfortunately they provide sufficient conditions only. This technical note proposes the use of homogeneous polynomial Lyapunov functions in the non-restrictive case where all the subsystems are Hurwitz, showing that a sufficient condition can be provided in terms of an LMI feasibility test by exploiting a key representation of polynomials. Several properties are proved for this condition, in particular that it is also necessary for a sufficiently large degree of these functions. As a result, the proposed condition provides a sequence of upper bounds of the minimum dwell time that approximate it arbitrarily well. Some examples illustrate the proposed approach.","Title: A Scaling And Squaring Method For The Discretisation Of Positive Switched Systems\nYear: 2011\n\nAbstract: In this paper we present a new method for approximating the matrix exponential of a Metzler matrix. This method is useful in discretising switched positive systems. In particular, the method preserves both linear and quadratic stability of the original continuous time system, as well as positivity of states starting for initial conditions in the positive orthant. The usefulness of the method is highlighted by illustrating some of the drawbacks of Pade approximations when applied to positive linear systems.","Title: An extension of the KYP-lemma for the design of state-dependent switching systems with uncertainty.\nYear: 2013\n\nAbstract: We consider the problem of designing state-dependent linear switching systems subject to parameter uncertainty. The switching rule is governed by a fixed partition of the state-space, and the parameter uncertainty appears in the matrices which determine the resulting dynamics. We derive a KYP-like lemma that can be used to design such systems in a manner that guarantees quadratic stability, for an arbitrary number of independent switching rules, each with its own switching region and its own domain of parameter uncertainty. Examples are given to illustrate the usefulness of our result.","Title: On Nonlinear Aimd Congestion Control For High-Speed Networks\nYear: 2006\n\nAbstract: This papers analyzses a class of nonlinear positive systems that model the dynamics of nonlinear additive-increase multiplicative-decrease (AIMD) protocols. The system class covers a range of protocols that are currently used in real communication networks, such as standard TCP, and recent proposals for congestion control protocols such as Scalable TCP.","Title: On The Fair Coexistence Of Loss- And Delay-Based Tcp\nYear: 2009\n\nAbstract: Delay-based TCP variants continue to attract a large amount of attention in the networking community. Potentially, they offer the possibility to efficiently use network resources while at the same time achieving low queueing delay and virtually zero packet loss. One major impediment to the deployment of delay-based TCP variants is their inability to coexist fairly with standard loss-based TCP. In this paper we propose a simple strategy to make the fair coexistence possible and to ensure that delay-based flows will revert back to the delay-based operation when loss-based flows are no longer present. Analytical and ns-2 simulation results are presented to validate the proposed algorithm.","Title: A novel pattern classification scheme using the Baker's map\nYear: 2003\n\nAbstract: We demonstrate a novel application of nonlinear systems in the design of pattern classification systems. We show that pattern classification systems can be designed based upon training algorithms designed to control the qualitative behaviour of a nonlinear system. Our paradigm is illustrated by means of a simple chaotic system—the Baker's map. Algorithms for training the system are presented and examples are given to illustrate the operation and learning of the system for pattern classification tasks.","Title: A methodology for the design of robust rollover prevention controllers for automotive vehicles: Part 1-Differential braking\nYear: 2006\n\nAbstract: In this paper, we apply recent results from robust control to the problem of rollover prevention in automotive vehicles. Specifically, we exploit the results of Pancake, Corless and Brockman, which provide controllers to robustly guarantee that the peak values of the performance outputs of an uncertain system do not exceed certain values. We introduce a new measure of performance for rollover prevention, the load transfer ratio LTRd, and design differential-braking-based rollover controllers to keep the value of this quantity below a certain level; we also obtain controllers which yield robustness to variations in vehicle speed. We present numerical simulations to demonstrate the efficacy of our controllers","Title: On the interpretation and identification of dynamic Takagi-Sugeno fuzzy models\nYear: 2000\n\nAbstract: Dynamic Takagi-Sugeno fuzzy models are not always easy to interpret, in particular when they are identified from experimental data. It is shown that there exists a close relationship between dynamic Takagi-Sugeno fuzzy models and dynamic linearization when using affine local model structures, which suggests that a solution to the multiobjective identification problem exists. However, it is also shown that the affine local model structure is a highly sensitive parametrization when applied in transient operating regimes. Due to the multiobjective nature of the identification problem studied here, special considerations must be made during model structure selection, experiment design, and identification in order to meet both objectives. Some guidelines for experiment design are suggested and some robust nonlinear identification algorithms are studied. These include constrained and regularized identification and locally weighted identification. Their usefulness in the present context is illustrated by examples","Title: On linear co-positive Lyapunov functions for sets of linear positive systems\nYear: 2009\n\nAbstract: In this paper we derive necessary and sufficient conditions for the existence of a common linear co-positive Lyapunov function for a finite set of linear positive systems. Both the state dependent and arbitrary switching cases are considered. Our results reveal an interesting characterisation of “linear” stability for the arbitrary switching case; namely, the existence of such a linear Lyapunov function can be related to the requirement that a number of extreme systems are Metzler and Hurwitz stable. Examples are given to illustrate the implications of our results.","Title: Deterministic and stochastic convergence properties of AIMD algorithms with nonlinear back-off functions\nYear: 2012\n\nAbstract: In this paper we establish basic stability results for a class of nonlinear AIMD (additive-increase multiplicative-decrease) algorithms. We consider networks in which the nonlinearity enters through the multiplicative-decrease mechanism. In particular, where the multiplicative-decrease function depends in a nonlinear fashion on the achieved rate. For synchronized deterministic networks, we establish stability and convergence results. For non-synchronized stochastic networks, basic convergence results are also established. In particular, we give conditions for the existence of a unique invariant stationary distribution, and conditions under which time- and ensemble-averages converge to the same unique value (irrespective of initial conditions).","Title: Distributed Probabilistic Synchronization Algorithms for Communication Networks\nYear: 2008\n\nAbstract: In this paper, we present a probabilistic synchronization algorithm whose convergence properties are examined using tools of row-stochastic matrices. The proposed algorithm is particularly well suited for wireless sensor network applications, where connectivity is not guaranteed at all times, and energy efficiency is an important design consideration. The tradeoff between the convergence speed and the energy use is studied.","Title: How expensive is link utilization?\nYear: 2007\n\nAbstract: Understanding the relationship between queueing delays and link utilization for general traffic conditions is an important open problem in networking research. Difficulties in understanding this relationship stem from the fact that it depends on the complex nature of arriving traffic and the problems associated with modelling such traffic. Existing AQM schemes achieve a \"low delay\" and \"high utilization\" by responding early to congestion without considering the exact relationship between delay and utilization. However, in the context of exploiting the delay/utilization tradeoff, the optimal choice of a queueing scheme's control parameter depends on the cost associated with the relative importance of queueing delay and utilization. The optimal choice of control parameter is the one that maximizes a benefit that can be defined as the difference between utilization and cost associated with queuing delay. We present a generic algorithm Optimal Delay-Utilization control of t (ODU-t) that is designed with a performance goal of maximizing this benefit. Its novelty lies in fact that it maximizes the benefit in an online manner, without requiring knowledge of the traffic conditions, specific delay-utilization models, nor does it require complex parameter estimation. Moreover, other performance metrics like loss rate or jitter can be directly incorporated into the optimization framework as well. Packet level ns2 simulations are given to demonstrate the behavior of the proposed algorithm.","Title: Beyond CHOKe: stateless fair queueing\nYear: 2007\n\nAbstract: Making drop decisions to enforce the max-min fair resource allocation in a network of standard TCP flows without any explicit state information is a challenging problem. Here we propose a solution to this problem by developing a suite of stateless queue management schemes that we refer to as Multi-Level Comparison with index l (MLC(l)). We show analytically, using a Markov chain model, that for an arbitrary network topology of standard TCP flows and queues employing MLC(l), the resource allocation converges to max-min fair as l increases. The analytical findings are verified experimentally using packet level ns2 simulations.","Title: Convex cones, lyapunov functions, and the stability of switched linear systems\nYear: 2003\n\nAbstract: Recent research on switched and hybrid systems has resulted in a renewed interest in determining conditions for the existence of a common quadratic Lyapunov function for a finite number of stable LTI systems. While efficient numerical solutions to this problem have existed for some time, compact analytical conditions for determining whether or not such a function exists for a finite number of systems have yet to be obtained. In this paper we present a geometric approach to this problem. By making a simplifying assumption we obtain a compact time-domain condition for the existence of such a function for a pair of LTI systems. We show a number of new and classical Lyapunov results can be obtained using our framework. In particular, we demonstrate that our results can be used to obtain compact time-domain versions of the SISO Kalman-Yacubovich-Popov lemma, the Circle Criterion, and stability multiplier criteria. Finally, we conclude by posing a number of open questions that arise as a result of our approach.","Title: Stability Criteria for Switched and Hybrid Systems.\nYear: 2007\n\nAbstract: The study of the stability properties of switched and hybrid systems gives rise to a number of interesting and challenging mathematical problems. The objective of this paper is to outline some of these problems, to review progress made in solving them in a number of diverse communities, and to review some problems that remain open. An important contribution of our work is to bring together material from several areas of research and to present results in a unified manner. We begin our review by relating the stability problem for switched linear systems and a class of linear differential inclusions. Closely related to the concept of stability are the notions of exponential growth rates and converse Lyapunov theorems, both of which are discussed in detail. In particular, results on common quadratic Lyapunov functions and piecewise linear Lyapunov functions are presented, as they represent constructive methods for proving stability and also represent problems in which significant progress has been made. We also comment on the inherent difficulty in determining stability of switched systems in general, which is exemplified by NP-hardness and undecidability results. We then proceed by considering the stability of switched systems in which there are constraints on the switching rules, through both dwell-time requirements and state-dependent switching laws. Also in this case the theory of Lyapunov functions and the existence of converse theorems are reviewed. We briefly comment on the classical Lur'e problem and on the theory of stability radii, both of which contain many of the features of switched systems and are rich sources of practical results on the topic. Finally we present a list of questions and open problems which provide motivation for continued research in this area.","Title: An experimental evaluation of distributed rate limiting for cloud computing applications\nYear: 2010\n\nAbstract: Pricing and load distribution in a cloud are difficult problems. In order to recover the construction costs of the data center, the owner must endeavour to have high utilization while maintaining performance levels for the users. Distributed Rate Limiting (DRL) is a mechanism that can be used to attack this problem. A mathematical framework and the convergence and stability properties of two DRL algorithms were examined in previous work. In this paper we build upon that work by evaluating the performance of these algorithms on a testbed against the results of a simulation carried out in previous work. We also evaluate the algorithms resilience to failure and propose the good-neighbours enhancement to improve its performance.","Title: Modelling TCP Throughput and Fairness\nYear: 2004\n\nAbstract: Since TCP traffic is elastic, a fundamental issue is the behaviour of multiple TCP flows competing for bandwidth on a shared link. Motivated by the ubiquity of drop-tail queueing in current networks, our focus in this paper is on developing analytic models suited to characterising the throughput and fairness of competing TCP flows in drop-tail environments. Building on recent ideas from the theory of positive linear systems, we obtain simple, insightful closed-form expressions for throughput and fairness. The accuracy of these expressions is confirmed in extensive simulations across a range of network conditions. In particular, they are found to provide accurate estimate of mean fairness and throughput even when flows are not synchronised.","Title: Analysis and design of AIMD congestion control algorithms in communication networks\nYear: 2005\n\nAbstract: We present a model of a network of synchronised sources operating additive increase multiplicative decrease (AIMD) congestion control algorithms. We show: (i) that networks of such devices in the presence of a drop-tail bottleneck buffer may be modelled as a positive linear system; (ii) that such networks possess a unique stationary point; and (iii) that this stationary point is globally exponentially stable. We use these results to establish conditions for the fair co-existence of traffic in networks employing heterogeneous AIMD algorithms and to design a new protocol for operation over high-speed and long-distance links.","Title: A control design method for a class of switched linear systems\nYear: 2009\n\nAbstract: In this note we consider the stability properties of a system class that arises in the control design problem of switched linear systems. The control design we are studying is based on a classical pole-placement approach. We analyse the stability of the resulting switched system and develop analytic conditions which reduce the complexity of the stability problem. We further consider two special cases for which strongly simplified conditions are obtained that support the analytic controller design.","Title: Load balancing vs. distributed rate limiting: an unifying framework for cloud control\nYear: 2009\n\nAbstract: With the expansion of cloud-based services, the question as to how to control usage of such large distributed systems has become increasingly important. Load balancing (LB), and recently proposed distributed rate limiting (DRL) have been used independently to reduce costs and to fairly allocate distributed resources. In this paper we propose a new mechanism for cloud control that unifies the use of LB and DRL: LB is used to minimize the associated costs and DRL makes sure that the resource allocation is fair. From an analytical standpoint, modelling the dynamics of DRL in dynamic workloads (resulting from LB cost-minimization scheme) is a challenging problem. Our theoretical analysis yields a condition that ensures convergence to the desired working regime. Analytical results are then validated empirically through several illustrative simulations. The closed-form nature of our result also allows simple design rules which, together with extremely low computational and communication overhead, makes the presented algorithm practical and easy to deploy.","Title: Preservation of common quadratic Lyapunov functions and Padé approximations\nYear: 2010\n\nAbstract: It is well known that the bilinear transform, or first order diagonal Padé approximation to the matrix exponential, preserves quadratic Lyapunov functions between continuous-time and corresponding discrete-time linear time invariant (LTI) systems, regardless of the sampling time. It is also well known that this mapping preserves common quadratic Lyapunov functions between continuous-time and discrete-time switched systems. In this note we show that while diagonal Padé approximations do not in general preserve other types of Lyapunov functions (or even stability), it is true that diagonal Padé approximations of the matrix exponential, of any order and sampling time, preserve quadratic stability. A consequence of this result is that the quadratic stability of switched systems is robust with respect to certain discretization methods.","Title: Optimal distributed power generation for thermal and electrical scheduling in a microgrid\nYear: 2013\n\nAbstract: This paper illustrates stochastic distributed algorithms that optimally share the electrical and thermal power generation task among the several Distributed Energy Resources (DERs) within a microgrid. We borrow certain concepts from communication network theory, namely Additive-Increase-Multiplicative-Decrease (AIMD) algorithms, which are known to be convenient in terms of communication requirements and network efficiency. We adapt them to minimise a cost utility function of interest in the framework of smart grids. We then implement the AIMD utility optimisation strategies in a realistic power network simulation in Matlab-OpenDSS environment, and we show the performance of the proposed algorithms in achieving thermal and electrical power balancing1.","Title: Synthesis Of Piecewise-Linear Chaotic Maps: Invariant Densities, Autocorrelations, And Switching\nYear: 2008\n\nAbstract: In this paper, we give a review of the Inverse Frobenius-Perron problem (IFPP): how to create chaotic maps with desired invariant densities. After describing some existing methods for solving the IFPP, we present a new and simple matrix method of doing this. We show how the invariant density and the autocorrelation properties of the maps can be controlled independently. We also give some fundamental results on switching between a number of different chaotic maps and the effect this has on the overall invariant density of the system. The invariant density of the switched system can be controlled by varying the probabilities of choosing each individual map. Finally, we present an interesting application of the matrix method to image generation, by synthesizing a two-dimensional map, which when iterated, generates a well-known image.","Title: A design methodology for switched discrete time linear systems with applications to automotive roll dynamics control\nYear: 2008\n\nAbstract: In this paper we consider the asymptotic stability of a class of discrete-time switching linear systems, where each of the constituent subsystems is Schur stable. We first present an example to motivate our study, which illustrates that the bilinear transform does not preserve the stability of a class of switched linear systems. Consequently, continuous time stability results cannot be transformed to discrete time analogs using this transformation. We then present a subclass of discrete-time switching systems that arise frequently in practical applications. We prove that global attractivity for this subclass can be obtained without requiring the existence of a common quadratic Lyapunov function (CQLF). Using this result, we present a synthesis procedure to construct switching stabilizing controllers for an automotive control problem, which is related to the stabilization of a vehicle’s roll dynamics subject to switches in the center of gravitys (CG) height.","Title: On Optimality Criteria for Reverse Charging of Electric Vehicles\nYear: 2014\n\nAbstract: Ever increasing expectations regarding the penetration level of electric vehicles (EVs) are driving several areas of research related to EV charging. One topic of interest treats EVs not only as controllable loads but also as storage systems, which can be used to mitigate the load on the grid during peak times by offering power. This is known as vehicle to grid (V2G). Since returning energy to the grid affects mobility patterns, V2G has an associated environmental cost. In this paper, to investigate this issue, we formulate the problem of returning electrical load to the grid as an optimization whose goal is to return the desired energy in a fashion that minimizes the cost on the environment. We show that this optimization is highly complex, and in some circumstances, the cost of V2G can be prohibitive.","Title: Modelling TCP congestion control dynamics in drop-tail environments\nYear: 2007\n\nAbstract: In this paper we study communication networks that employ drop-tail queueing and additive-increase multiplicative-decrease (AIMD) congestion control algorithms. We show that the theory of non-negative matrices may be employed to model such networks and to derive basic theorems concerning their behaviour.","Title: A Numerical Technique for Stability Analysis of Linear Switched Systems\nYear: 2004\n\nAbstract: Summary In this report the ray-gridding approach, a new numerical technique for the stability analysis of linear switched systems is presented. It is based on uniform partitions of the state-space in terms of ray directions which allow reflnable families of polytopes of adjustable complexity to be examined for invariance. In this framework the existence of a polyhedral Lyapunov function that is common to a family of asymptotically stable subsystems can be checked e-ciently via simple iterative algorithms. The technique can be used to prove the stability of switched linear systems, classes of linear time- varying systems and Linear Difierential Inclusions. We also present preliminary results on two other related problems; namely, the existence of stabilis- ing switching sequences for a switched system constructed from a family of unstable linear subsystems","Title: A result on second order nonlinear operators arising in high-speed networking applications\nYear: 2009\n\nAbstract: We consider the behaviour of a class of nonlinear difference equations that arise in networks employing congestion control protocols. For a class of such systems we show that trajectories, experiencing the same set of congestion notifications, but starting at different initial conditions, converge exponentially to each other.","Title: On a class of generalized eigenvalue problems and equivalent eigenvalue problems that arise in systems and control theory\nYear: 2011\n\nAbstract: Systems and control theory has long been a rich source of problems for the numerical linear algebra community. In many problems, conditions on analytic functions of a complex variable are usually evaluated by solving a special generalized eigenvalue problem. In this paper we develop a general framework for studying such problems. We show that for these problems, solutions can be obtained by either solving a generalized eigenvalue problem, or by solving an equivalent eigenvalue problem. A consequence of this observation is that these problems can always be solved by finding the eigenvalues of a Hamiltonian (or discrete-time counterpart) matrix, even in cases where an associated Hamiltonian matrix, cannot (normally) be defined. We also derive a number of new compact tests for determining whether or not a transfer function matrix is strictly positive real. These tests, which are of independent interest due to the fact that many problems can be recast as SPR problems, are defined even in the case when the matrix D+D^* is singular, and can be formulated without requiring inversion of the system matrix A.","Title: Stratus: Load Balancing the Cloud for Carbon Emissions Control.\nYear: 2013\n\nAbstract: Large public cloud infrastructure can utilise power which is generated by a multiplicity of power plants. The cost of electricity will vary among the power plants and each will emit different amounts of carbon for a given amount of energy generated. This infrastructure services traffic that can come from anywhere on the planet. It is desirable, for latency purposes, to route the traffic to the dat...","Title: Classical Results on the Stability of Linear Time-Invariant Systems, and the Schwarz Form.\nYear: 2014\n\nAbstract: The paper deals with the classical results of Routh and Hurwitz, Biehler and Kharitonov, concerning the stability of a linear time invariant differential equation. It is shown that these results follow directly from a Schwarz matrix representation of stable systems.","Title: Preservation of quadratic stability under various common approximate discretization methods.\nYear: 2014\n\nAbstract: In this paper we prove the following result. If A is a Hurwitz matrix and f is a rational function that maps the open left half of the complex plane into the open unit disc, then any Hermitian matrix P>0 which is a Lyapunov matrix for A (that is, PA+A∗P<0) is also a Stein matrix for f(A) (that is, f(A)∗Pf(A)−P<0).","Title: On the quadratic stability of switched linear systems associated with symmetric transfer function matrices.\nYear: 2014\n\nAbstract: In this paper we give necessary and sufficient conditions for weak and strong quadratic stability of a class of switched linear systems consisting of two subsystems, associated with symmetric transfer function matrices. These conditions can simply be tested by checking the eigenvalues of the product of two subsystem matrices. This result is an extension of the result by Shorten and Narendra for strong quadratic stability, and the result by Shorten et al. on weak quadratic stability for switched linear systems. Examples are given to illustrate the usefulness of our results.","Title: Plug-and-Play Distributed Algorithms for Optimized Power Generation in a Microgrid.\nYear: 2014\n\nAbstract: This paper introduces distributed algorithms that share the power generation task in an optimized fashion among the several Distributed Energy Resources (DERs) within a microgrid. We borrow certain concepts from communication network theory, namely Additive-Increase-Multiplicative-Decrease (AIMD) algorithms, which are known to be convenient in terms of communication requirements and network effici...","Title: A-stable Padé approximations and quadratic stability\nYear: 2013\n\nAbstract: In this paper we prove that all A-stable Padé approximations for the matrix exponential preserve common quadratic Lyapunov functions for switched linear systems.","Title: Stability of a class of switched descriptor systems\nYear: 2013\n\nAbstract: In this paper we use the dimensionality reduction result from [1] for linear descriptor systems to derive stability conditions for special classes of switched descriptor systems.","Title: A Note on Discretization of Sparce Linear Systems.\nYear: 2012\n\nAbstract: In this paper a modified Euler transformation is introduced and studied. The main merit of this transformation is to outperform stability preservation (with respect to the traditional Euler transformation) besides preserving the matrix sparseness. This is particular appealing in the analysis of positive systems since it is shown that stability is preserved independent of the sampling period. A brief collection of results for switched systems has been also provided.","Title: Delay-Tolerant Stochastic Algorithms for Parking Space Assignment\nYear: 2014\n\nAbstract: This paper introduces and illustrates some novel stochastic policies that assign parking spaces to cars looking for an available parking space. We analyze in detail both the main features of a single park, i.e., how a car could conveniently decide whether to try its luck at that parking lot or try elsewhere, and the case when more parking lots are available, and how to choose the best one. We discuss the practical requirements of the proposed strategies in terms of infrastructure technology and vehicles' equipment and the mathematical properties of the proposed algorithms in terms of robustness against delays, stability, and reliability. Preliminary results obtained from simulations are also provided to illustrate the feasibility and the potential of our stochastic assignment policies.","Title: On the Dynamics of TCP's Higher Moments\nYear: 2007\n\nAbstract: In this paper we extend a recently derived positive systems model for TCP to capture the dynamics of TCP's higher order moments in drop-tail environments. Experimental results are given to illustrate the accuracy of our model","Title: On Queue Provisioning, Network Efficiency and the Transmission Control Protocol\nYear: 2007\n\nAbstract: In this paper, we propose a sender side modification to TCP to accommodate small network buffers. We exploit the fact that the manner in which network buffers are provisioned is intimately related to the manner in which TCP operates. However, rather than designing buffers to accommodate the TCP AIMD algorithm, as is the traditional approach in network design, we suggest simple modifications to the AIMD algorithm to accommodate buffers of any size in the network. We demonstrate that networks with small buffers can be designed that transport TCP traffic in an efficient manner while retaining fairness and friendliness with standard TCP traffic.","Title: On AIMD Congestion Control in Multiple Bottleneck Networks\nYear: 2007\n\nAbstract: We consider a linear algebraic model of the Additive-Increase Multiplicative-Decrease congestion control algorithm and present results on average fairness and convergence for multiple bottleneck networks. Results are presented for networks of both long-lived and short-lived flows.","Title: A correct characterization of strict positive realness for MIMO systems\nYear: 2009\n\nAbstract: We present conditions which are necessary and sufficient for a transfer function (or transfer function matrix) to be strictly positive real. A counter example is given to illustrate that, in the MIMO (multi-input multi-output) case, the conditions presented here differ from those previously presented in the literature, and that these same conditions represent an incomplete characterization of strict positive realness (and passivity).","Title: A characterization of the Hurwitz stability of Metzler matrices\nYear: 2009\n\nAbstract: It is well known that a Hurwitz Metzler matrix is also diagonally stable. We obtain a necessary and sufficient condition for a matrix A to be diagonally stable from the Kalman-Yacubovich-Popov lemma. This condition is equivalent to requiring that a pair of LTI systems, of lower dimension, have a common Lyapunov function. This fact is made use of to derive very simple conditions for the Hurwitz stability of a Metzler matrix. These conditions are stated in terms of the signs of the diagonal entries of a sequence of lower dimensional matrices that are easily constructed.","Title: A strategy for fair coexistence of loss and delay-based congestion control algorithms\nYear: 2009\n\nAbstract: Delay-based TCP variants have attracted a large amount of attention in the networking community because of their ability to efficiently use network resources, control queuing delays, exhibit virtually zero packet loss, etc. One major issue that discourages the wider deployment of delay-based TCP variants is their inability to co-exist fairly with standard loss-based TCP. In this note we propose a simple mechanism that allows delay- and loss-based (AIMD) TCP flows to compete fairly with each other. Further, our approach ensures that delay-based flows automatically (and swiftly) switch to a low-delay regime if no loss-based flows are present. We provide analytical and simulation results to validate presented algorithm.","Title: \"Fair-Share\" for Fair Bandwidth Allocation in Cloud Computing\nYear: 2012\n\nAbstract: Current mechanisms for controlling network resources cannot prevent users from interfering with each other in a shared cloud environment. Proposals made to rectify this, use mechanisms which require interrupts with high timing precision, and usually unevenly distribute bandwidth to TCP flows. We propose the use of an alternative mechanism to manage network resources and compare the performance of both.","Title: Generalized distributed rate limiting\nYear: 2009\n\nAbstract: The distributed rate limiting (DRL) paradigm is a recently proposed mechanism for decentralized control of cloud-based services. DRL is a simple and efficient approach to resolve the issues of pricing and resource control/engineering of cloud based services. The existing DRL schemes focus on very specific performance metrics (such as loss rate and fair-share) and their design heavily depends on the assumption that the traffic is generated by elastic TCP sources. In this paper we tackle the DRL problem for general workloads and performance metrics and propose an analytic framework for the design of stable DRL algorithms. The closed-form nature of our results allows simple design rules which, together with extremely low communication overhead, makes the presented algorithms practical and easy to deploy with guaranteed convergence properties under a wide range of possible scenarios.","Title: Cooperative Regulation and Trading of Emissions Using Plug-in Hybrid Vehicles\nYear: 2013\n\nAbstract: We present a new approach to regulate traffic-related pollution in urban environments by utilizing hybrid vehicles. To do this, we orchestrate the way that each vehicle in a large fleet combines its two engines based on simple communication signals from a central infrastructure. Our approach can be viewed both as a control algorithm and as an optimization algorithm. The primary goal is to regulate emissions, and we discuss a number of control strategies to achieve this goal. Second, we want to allocate the available pollution budget in a fair way among the participating vehicles; again, we explore several different notions of fairness that can be achieved. The efficacy of our approach is exemplified both by the construction of a proof-of-concept vehicle and by extensive simulations, and is verified by mathematical analysis.","Title: Stochastic Park-and-Charge Balancing for Fully Electric and Plug-in Hybrid Vehicles\nYear: 2014\n\nAbstract: Motivated by the need to provide services to alleviate range anxiety of electric vehicles, we consider the problem of balancing charging demand across a network of charging stations. Our objective is to reduce the potential for excessively long queues to build up at some charging stations, although other charging stations are underutilized. A stochastic balancing algorithm is presented to achieve these goals. A further feature of this algorithm is that it is fully decentralized and facilitates a plug-and-play type of behavior. Using our system, the charging stations can join and leave the network without any changes to, or communication with, a centralized infrastructure. Analysis and simulations are presented to illustrate the efficacy of our algorithm.","Title: Padé Discretization for Linear Systems With Polyhedral Lyapunov Functions\nYear: 2011\n\nAbstract: This technical note has been motivated by the need to assess the preservation of polyhedral Lyapunov functions for stable continuous-time linear systems under numerical discretization of the transition matrix. This problem arises when discretizing linear systems in such a manner as to preserve a certain type of stability of the discrete time approximation. Our main contribution is to show that a continuous-time system and its Padé discretization (of any order and sampling) always share at least one common piecewise linear (polyhedral) Lyapunov function.","Title: Adaptive williams filters with application to suspension control: The vector case\nYear: 2009\n\nAbstract: With active vehicle suspension, one can tailor a vehicle's response to load and inertial disturbances without affecting the vehicle response to road disturbances. This decoupling is achieved by previous researchers and using a filtered combination of measured signals. These filters, which we call Williams filters, require exact knowledge of certain vehicle parameters including vehicle mass to achieve the desired decoupling. However, vehicle parameters, such as mass, are subject to abrupt variations as vehicle load changes. We propose an adaptive Williams filter that does not require knowledge of vehicle parameters and extends the results presented in.","Title: Hurwitz Stability of Metzler Matrices\nYear: 2010\n\nAbstract: In this note, a simple method is presented that is both necessary and sufficient for determining whether a given Metzler matrix A is Hurwitz. The method is based on the well known fact that a Hurwitz Metzler matrix is also diagonally stable. By using this fact, very simple conditions are derived for the Hurwitz stability of a Metzler matrix. The conditions are stated in terms of the signs of the diagonal entries of a sequence of lower dimensional matrices. The efficacy of the conditions is demonstrated by applying them to determine stability in several examples.","Title: On the Characterization of Strict Positive Realness for General Matrix Transfer Functions\nYear: 2010\n\nAbstract: We present conditions which are necessary and sufficient for a transfer function (or transfer function matrix) to be strictly positive real. A counter-example is given to illustrate that the conditions presented here differ from those previously presented in the literature. The proof of our results differs from previous related proofs in that it only uses properties of analytic functions and matrices and does not require state-space realizations. Also, the results are not restricted to rational transfer functions with real coefficients.","Title: Distributed Dynamic Speed Scaling\nYear: 2010\n\nAbstract: In recent years we have witnessed a great interest in large distributed computing platforms, also known as clouds. While these systems offer enormous computing power, they are major energy consumers. In existing data centers CPUs are responsible for approximately half of the energy consumed by the servers. A promising technique for saving CPU energy consumption is dynamic speed scaling, in which the speed at which the processor is run is adjusted based on demand and performance constraints. In this paper we look at the problem of allocating the demand in the network of processors (each being capable to perform dynamic speed scaling) to minimize the global energy consumption/cost subject to a performance constraint. The nonlinear dependence between the energy consumption and the performance as well as the high variability in the energy prices result in a nontrivial resource allocation. The problem can be abstracted as a fully distributed convex optimization with a linear constraint. On the theoretical side, we propose two low-overhead fully decentralized algorithms for solving the problem of interest and provide closed-form conditions that ensure stability of the algorithms. Then we evaluate the efficacy of the optimal solution using simulations driven by the real-world energy prices. Our findings indicate a possible cost reduction of 10-40% compared to power-oblivious 1/N load balancing, for a wide range of load factors.","Title: Extensions of “Padé Discretization for Linear Systems With Polyhedral Lyapunov Functions” for Generalized Jordan Structures\nYear: 2013\n\nAbstract: Recently, we showed that certain types of polyhedral Lyapunov functions for linear time-invariant systems, are preserved by diagonal Padé approximations, under the assumption that the continuous-time system matrix Ac has distinct eigenvalues. In this technical note, we show that this result also holds true in the case that Ac has non-trivial Jordan blocks.","Title: Signaled Queueing\nYear: 2015\n\nAbstract: Burstiness in queues where customers arrive independently leads to rush periods when wait times are long. We propose a simple signaling scheme to decrease wait times by distributing customer arrivals more uniformly. Agents receive one of several signals with suggestions on what time to join the queue. We quantify the efficiency gains, both analytically and empirically, with respect to a number of parameters of the proposed signaled queue, such as burstiness of arrivals, number of distinct signals, and propensity of customers to follow suggestions.","Title: Data Assimilation for Linear Parabolic Equations: Minimax Projection Method\nYear: 2015\n\nAbstract: In this paper we propose a state estimation method for linear parabolic partial differential equations (PDE) that accounts for errors in the model, truncation, and observations. It is based on an extension of the Galerkin projection method. The extended method models projection coefficients, representing the state of the PDE in some basis, by means of a differential-algebraic equation (DAE). The original estimation problem for the PDE is then recast as a state estimation problem for the constructed DAE using a linear continuous minimax filter. We construct a numerical time integrator that preserves the monotonic decay of a nonstationary Lyapunov function along the solution. To conclude, we demonstrate the efficacy of the proposed method by applying it to the tracking of a discharged pollutant slick in a two-dimensional fluid.","Title: Smart Procurement of Naturally Generated Energy (SPONGE) for Plug-in Hybrid Electric Buses.\nYear: 2017\n\nAbstract: We discuss a recently introduced ECO-driving concept known as smart procurement of naturally generated energy (SPONGE) in the context of plug-in hybrid electric buses. Examples are given to illustrate the benefits of this approach to ECO-driving. Finally, distributed algorithms to realize SPONGE are discussed, paying attention to the privacy implications of the underlying optimization problems.","Title: An Ergodic Aimd Algorithm With Application To High-Speed Networks\nYear: 2012\n\nAbstract: In this article we propose a version of the Additive-Increase Multiplicative-Decrease (AIMD) algorithm that provides a suitable basis to develop congestion control protocols that can be deployed in both conventional and high-speed communication networks. Our algorithm retains many of the properties of the standard AIMD algorithm. However, unlike other non-standard AIMD algorithms, our scheme can be shown to be ergodic under very general assumptions.","Title: A Google-Like Model Of Road Network Dynamics And Its Application To Regulation And Control\nYear: 2011\n\nAbstract: Inspired by the ability of Markov chains to model complex dynamics and handle large volumes of data in Google's PageRank algorithm, a similar approach is proposed here to model road network dynamics. The central component of the Markov chain is the transition matrix which can be completely constructed by easily collecting traffic data. The proposed model is validated using the popular mobility simulator SUMO. Markov chain theory and spectral analysis of the transition matrix are then shown to reveal non- evident properties of the underlying road network and to correctly predict consequences of road network modifications. Preliminary results from possible applications are shown and simple practical examples are provided throughout this article to clarify and support the theoretical expectations.","Title: Some Results On Quadratic Stability Of Switched Systems With Interval Uncertainty\nYear: 2007\n\nAbstract: Some results on quadratic stability of switched systems with interval uncertainty In this paper we present some results on the quadratic stability of switched systems with uncertain parameters. We show that the quadratic stability of a class of switched uncertain systems may be readily verified using simple algebraic conditions.","Title: A Framework For Decentralised Feedback Connectivity Control With Application To Sensor Networks\nYear: 2009\n\nAbstract: In this article, we propose a decentralised algorithm for connectivity maintenance in a distributed sensor network. Our algorithm uses the dynamics of a consensus algorithm to estimate the connectivity of a network topology in a decentralised manner. These estimates are then used to inform a decentralised control algorithm that regulates the network connectivity to some desired level. Under certain realistic assumptions we show that the closed-loop dynamics can be described as a consensus algorithm with an input, and eventually reduces to a scalar system. Bounds are given to ensure the stability of the algorithm and examples are given to illustrate the efficacy of the proposed algorithm.","Title: Strict Positive Realness Of Descriptor Systems In State Space\nYear: 2010\n\nAbstract: In this article, we give necessary and sufficient spectral conditions for various notions of strict positive realness for single-input single-output descriptor systems. These conditions only require calculation of eigenvalues of a single matrix. A characterisation of a Kalman-Yacubovich-Popov-like lemma for descriptor systems is also derived, and its implications for the stability of a class of switched descriptor systems are briefly discussed.","Title: Traffic Modelling Framework For Electric Vehicles\nYear: 2012\n\nAbstract: This article reviews and improves a recently proposed model of road network dynamics. The model is also adapted and generalised to represent the patterns of battery consumption of electric vehicles travelling in the road network. Simulations from the mobility simulator SUMO are given to support and to illustrate the efficacy of the proposed approach. Applications relevant in the field of electric vehicles, such as optimal routing and traffic load control, are provided to illustrate how the proposed model can be used to address typical problems arising in contemporary road network planning and electric vehicle mobility.","Title: A Flexible Distributed Framework For Realising Electric And Plug-In Hybrid Vehicle Charging Policies\nYear: 2012\n\nAbstract: Motivated by the problems of charging a number of electric vehicles via limited capacity infrastructure, this article considers the problem of individual load adjustment under a total capacity constraint. For reasons of scalability and simplified communications, distributed solutions to this problem are sought. Borrowing from communication networks (AIMD algorithms) and distributed convex optimisation, we describe a number of distributed algorithms for achieving relative average fairness whilst maximising utilisation. We present analysis and simulation results to show the performance of these algorithms. In the scenarios examined, the algorithm's performance is typically within 5% of that achievable in the ideal centralised case, but with greatly enhanced scalability and reduced communication requirements.","Title: Results In Cooperative Control And Implicit Consensus\nYear: 2011\n\nAbstract: This article is concerned with a class of decentralised control problems that arise in contemporary applications, where agents cooperate to control and regulate a global quantity, are limited in the manner in which they communicate with each other, and are required to reach consensus on some implicit variable (e. g. CO2 emissions). Three algorithms are presented for achieving this goal. The convergence of these algorithms are proven, and their efficacy is demonstrated in simulations.","Title: Exact stability test and stabilization for fractional systems\nYear: 2015\n\nAbstract: In this paper we point out a connection between regular chains and the stability of fractional order systems. This observation leads to an elementary test for the stability of commensurate fractional systems.","Title: On The Design And Synthesis Of Limit Cycles Using Switching Linear Systems\nYear: 2010\n\nAbstract: This article deals with the design and synthesis of limit cycles for a class of switched linear systems. This work is motivated by an application in the context of electrical networks, but the methodologies can be applied in other engineering fields as well. Several methods for the design and synthesis of limit cycles are presented. Based on a monodromy matrix associated with a periodically switched system, a design method and two feedback strategies are developed. The first strategy is based on linear feedback design using pole placement. The second strategy is based on the observation that certain state-dependent switching strategies can be implemented by means of a simple nonlinear output feedback controller. Advantages of this latter strategy are not only the ease with which the switching strategy can be implemented, but also the fact that classical techniques may also be used to ascertain the stability of the resulting limit cycle. Our next contribution is the development of a novel frequency domain-based approach to limit cycle design. This approach is based on the observation that the existence of certain limit cycles can be deduced from an infinity of circle criteria generated by a family of periodic systems. By making use of recent results, this observation can be used to develop a one-parameter spectral search to deduce the approximate frequencies of feasible limit cycles. Having selected a frequency of oscillation, one may then make use of the aforementioned nonlinear elements to realise a switching strategy that generates a stable limit cycle with given frequency and amplitude. Examples are given to illustrate the effectiveness of the approaches presented.","Title: On Maximum Sector Bounds For Absolute Stability Of Single-Input Single-Output Systems\nYear: 2007\n\nAbstract: We consider the classical problem of absolute stability, i.e. stability of a linear time-invariant system in feedback with a memoryless time-varying sector bound non-linearity. We derive necessary and sufficient conditions for the existence of periodic motion. For the special case of symmetric sector bounds, this condition yields the minimum sector bounds for which the system can sustain periodic motion. By guaranteeing the absence of periodic motion we derive non-conservative sufficient conditions for absolute stability for arbitrary sector bounds. We demonstrate by numerical examples the application of our results.","Title: Comments And Observations On The Passivity Of Descriptor Systems In State Space\nYear: 2013\n\nAbstract: In this article, we give necessary and sufficient conditions for passivity of descriptor systems. These conditions are easily verifiable and apply without restriction to all descriptor systems.","Title: A Methodology For The Design Of Robust Rollover Prevention Controllers For Automotive Vehicles With Active Steering\nYear: 2007\n\nAbstract: In this paper we present a robust controller design methodology for vehicle rollover prevention utilizing active steering. Control design is based on keeping the magnitude of the vehicle load transfer ratio (LTR) below a certain level in the presence of driver steering inputs; we also develop an exact expression for LTR. The proposed controllers have a proportional-integral structure whose gain matrices are obtained using the results of Pancake et al. (2000) (T. Pancake, M. Corless and M. Brockman, \"Analysis and control of polytopic uncertain/nonlinear systems in the presence of bounded disturbance inputs'', Proceedings of the American Control Conference, Chicago, IL, June 2000; T. Pancake, M. Corless and M. Brockman, \"Analysis and control for a class of uncertain/nonlinear systems in the presence of bounded disturbance inputs'', 2007). These controllers reduce the transient magnitude of the LTR while maintaining the steady state steering response of the vehicle. The controllers can be designed to be robust with respect to vehicle parameters such as speed and centre of gravity height. We also provide a modi. cation to the controllers so that they only activate when the potential for rollover is significant. Numerical simulations demonstrate the efficacy of our approach and the resulting controllers.","Title: Optimal Real-Time Distributed V2g And G2v Management Of Electric Vehicles\nYear: 2014\n\nAbstract: This paper exploits the analogy between the electrical grid and modern communication networks to implement Electric Vehicle (EV) battery charging scheduling algorithms inspired by popular communication network techniques. In preliminary works, a similar approach was used to manage the Grid-to-Vehicle (G2V) active power flows. In this paper, we extend this framework to both implement the Vehicle-to-Grid (V2G) concept and to provide reactive power compensation capabilities that do not affect charging times. The ability of the proposed algorithms to optimally share the available/desired power in a fair way, with minimum communication requirements, in a very uncertain, dynamically changing framework, is illustrated through several examples for different scenarios of interest.","Title: Signalling And Obfuscation For Congestion Control\nYear: 2015\n\nAbstract: We aim to reduce the social cost of congestion in many smart city applications. In our model of congestion, agents interact over limited resources after receiving signals from a central agent that observes the state of congestion in real time. Under natural models of agent populations, we develop new signalling schemes and show that by introducing a non-trivial amount of uncertainty in the signals, we reduce the social cost of congestion, i.e., improve social welfare. The signalling schemes are efficient in terms of both communication and computation, and are consistent with past observations of the congestion. Moreover, the resulting population dynamics converge under reasonable assumptions.","Title: A Big-Data Model For Multi-Modal Public Transportation With Application To Macroscopic Control And Optimisation\nYear: 2015\n\nAbstract: This paper describes a Markov-chain-based approach to modelling multi-modal transportation networks. An advantage of the model is the ability to accommodate complex dynamics and handle huge amounts of data. The transition matrix of the Markov chain is built and the model is validated using the data extracted from a traffic simulator. A realistic test-case using multi-modal data from the city of London is given to further support the ability of the proposed methodology to handle big quantities of data. Then, we use the Markov chain as a control tool to improve the overall efficiency of a transportation network, and some practical examples are described to illustrate the potentials of the approach.","Title: Alleviating A Form Of Electric Vehicle Range Anxiety Through On-Demand Vehicle Access\nYear: 2015\n\nAbstract: On-demand vehicle access is a method that can be used to reduce types of range anxiety problems related to planned travel for electric vehicle owners. Using ideas from elementary queueing theory, basic quality of service (QoS) metrics are defined to dimension a shared fleet to ensure high levels of vehicle access. Using mobility data from Ireland, it is argued that the potential cost of such a system is very low.","Title: On Closed-Loop Bicycle Availability Prediction\nYear: 2015\n\nAbstract: We study the effect of customer choices in bicycle-sharing systems based on bicycle availability predictions. We show that such systems may lead to flapping behavior between bicycle stations. The consequences of flapping instability include poor user experience and suboptimal usage of the available bicycle stock. We propose a simple assignment strategy aimed at eliminating flapping and balancing d...","Title: Person-Specific Standardized Vulnerability Assessment in Health and Social Care.\nYear: 2015\n\nAbstract: We describe an integrated person-specific standardized vulnerability assessment model designed to facilitate patient management in health and social care. Such a system is not meant to replace existing health and social assessment models but rather to complement them by providing a holistic picture of the vulnerabilities faced by a given patient. In fact, it should be seen as a screening tool for health and social care workers. One key aspect of the modeling framework is the ability to provide personalized yet standardized multi-dimensional assessments of risk based on incomplete information about the patient status, as is the case in screening situations. Specifically, we integrate a Markov chain model describing the evolution of patients in and out of vulnerable states over time with a Bayesian network that serves to customize the dynamic model. We present an application in the context of elder care.","Title: Smart Procurement Of Naturally Generated Energy (Sponge) For Phevs\nYear: 2016\n\nAbstract: In this paper, we propose a new engine management system for hybrid vehicles to enable energy providers and car manufacturers to provide new services. Energy forecasts are used to collaboratively orchestrate the behaviour of engine management systems of a fleet of plug-in hybrid electric vehicle (PHEVs) to absorb oncoming energy in a smart manner. Cooperative algorithms are suggested to manage the energy absorption in an optimal manner for a fleet of vehicles, and the mobility simulator SUMO (Simulation of Urban MObility) is used to demonstrate the efficacy of the proposed idea.","Title: On Source-Term Parameter Estimation for Linear Advection-Diffusion Equations with Uncertain Coefficients.\nYear: 2016\n\nAbstract: In this paper, we propose an algorithm for estimating parameters of a source term of a linear advection-diffusion equation with an uncertain advection-velocity field. First, we apply a minimax state estimation technique in order to reduce uncertainty introduced by the coefficients. Then we design a source localization algorithm which uses the state estimator as a model and estimates the parameters of the source term given incomplete and noisy data. The principal novelty of the proposed algorithm is in that it is robust with respect to uncertainty in advection coefficients. The localization algorithm is sequential; that is, it updates both the state estimate and the source estimate once a new observation arrives. To demonstrate the efficacy of the proposed algorithm, we present a numerical example of source localization in two spatial dimensions for the advection-dominated transport of a nonreactive pollutant emanating from a point source.","Title: An intelligent speed advisory system for electric vehicles\nYear: 2015\n\nAbstract: Intelligent Transportation Systems (ITS) can be used to involve vehicles and the road infrastructure to cooperatively implement a number of innovative and useful applications. Here, we explore the possibility to adopt a consensus based distributed speed advisory system to determine the optimal recommended speed in urban areas where only electric vehicles are allowed to travel (e.g., in the city centre). The optimality criterion is to maximise the energy efficiency of a fleet of vehicles travelling in the restricted area, and we adopt recently proposed distributed privacy-preserving consensus algorithms to achieve the desired objective.","Title: A Markov-chain based model for a bike-sharing system\nYear: 2015\n\nAbstract: Bike-sharing systems are recently becoming ubiquitous in most cities, as an environmentally friendly alternative to other means of transportation. An optimal management of the bike-sharing service would in principle benefit from the availability of a mathematical model underlying the system. Accordingly, in this paper we propose a Markov-chain based approach to model the bike-sharing system, which we believe has a potential to develop alternative methods to implement classic control actions in a bike-sharing system (e.g., in terms of implementing alternative relocation strategies or planning advertising campaigns). The proposed methodology is validated on real data from the bike-sharing system in Boston, USA, and a first application of the proposed model is preliminarily illustrated in the paper.","Title: Localization of missing entities using parked cars\nYear: 2015\n\nAbstract: We introduce a novel application to detect tagged entities using a platform based on parked cars. We show experimental results based on real data from the city of Dublin.","Title: Cooperative control and smart procurement of naturally generated energy (SPONGE) for PHEVs\nYear: 2015\n\nAbstract: Electric vehicles can potentially be the best means of transportation for improving air quality, provided that they are powered by electricity from natural gas or wind, water or solar power. In this paper we describe a simple cooperative algorithm that exploits the energy management units of Plug-in Hybrid Electric Vehicles (PHEVs) to absorb the expected forthcoming energy available from renewable sources. The proposed approach bridges the gap between mobility patterns and power grid constraints, and allows to prevent green energy from being wasted while at the same time reducing the complexity burden of the power grid to charge unexpected loads of electric vehicles. Simulation results are given to show the efficacy of the proposed method.","Title: Pedestrian-Aware Engine Management Strategies for Plug-in Hybrid Electric Vehicles.\nYear: 2018\n\nAbstract: Electric vehicles (EVs) and plug-in hybrid EVs (PHEVs) are increasingly being seen as a means of mitigating the pressing concerns of traffic-related pollution. While hybrid vehicles are usually designed with the objective of minimizing fuel consumption, in this paper we propose a engine management strategies that also consider environmental effects of the vehicles to pedestrians outside of the veh...","Title: On The Design Of A Route Parsing Engine For Connected Vehicles With Applications To Congestion Management Systems\nYear: 2016\n\nAbstract: In this paper we present a new type of congestion management system to regulate congestion around a single link obstruction. This obstruction will be investigated in two cases: a) a regular obstruction and b) an irregular obstruction. The principle innovations of our system are to utilise a route parsing engine to both predict the likelihood of a vehicle being affected by the obstruction and make decisions ahead of time, and to use this information to make a fair congestion management system.","Title: Consensus With State Obfuscation: An Application To Speed Advisory Systems\nYear: 2016\n\nAbstract: In this paper, we present a new speed advisory system (SAS). The system provides indications to drivers which, if followed, guide the network of vehicles towards a common speed. The SAS we present is distributed and one of its key features is that the vehicles are guided towards the common speed by receiving obfuscated information. Essentially, this means that the desired network behaviour is achieved and, at the same time, there is no vehicle in the network that obtains clear knowledge of the state of any other vehicle. This results in a privacy-preserving feature which is particularly useful in smart cities applications, where drivers might not be willing to share their transient state with others.","Title: Hybrid Urban Navigation For Smart Cities\nYear: 2017\n\nAbstract: This paper proposes a design for a hybrid, citywide urban navigation system for moving agents demanding dedicated navigation support. The system combines GPS and vehicle-to-vehicle communication from an ad-hoc network of parked cars, and RFID from fixed infrastructure-such as smart traffic lights-to enable a safely navigable city. Applications for such a system include high speed drone navigation and directing visually impaired pedestrians.","Title: Cyberphysics, pollution mitigation, and pedelecs.\nYear: 2017\n\nAbstract: The effect of transport-related pollution on human health is fast becoming recognised as a major issue in cities worldwide. Cyclists, in particular, face great risks, as they typically are most exposed to tail-pipe emissions. Three avenues are being explored worldwide in the fight against urban pollution: (i) outright bans on polluting vehicles and embracing zero tailpipe emission vehicles; (ii) measuring air-quality as a means to better informing citizens of zones of higher pollution; and (iii) developing smart mobility devices that seek to minimize the effect of polluting devices on citizens as they transport goods and individuals in our cities. Following this latter direction, in this paper we present a new way to protect cyclists from the effect of urban pollution. Namely, by exploiting the actuation possibilities afforded by pedelecs or e-bikes (electric bikes), we design a cyber-physical system that mitigates the effect of urban pollution by indirectly controlling the breathing rate of cyclists in polluted areas. Results from a real device are presented to illustrate the efficacy of our system.","Title: On the stability and convergence of a class of consensus systems with a nonlinear input.\nYear: 2017\n\nAbstract: We consider a class of consensus systems driven by a nonlinear input. Such systems arise in a class of Internet of Things (IOT) applications. Our objective in this paper is to determine conditions under which a certain partially distributed system converges to a Lur’e-like scalar system, and to provide a rigorous proof of its stability. Conditions are derived for the non-uniform convergence and stability of such a system and an example is given of a speed advisory system where such a system arises.","Title: Distributed Multi-resource Allocation with Little Communication Overhead.\nYear: 2017\n\nAbstract: We propose a distributed algorithm to solve a special distributed multi-resource allocation problem with no direct inter-agent communication. We do so by extending a recently introduced additive-increase multiplicative-decrease (AIMD) algorithm, which only uses very little communication between the system and agents. Namely, a control unit broadcasts a one-bit signal to agents whenever one of the allocated resources exceeds capacity. Agents then respond to this signal in a probabilistic manner. In the proposed algorithm, each agent is unaware of the resource allocation of other agents. We also propose a version of the AIMD algorithm for multiple binary resources (e.g., parking spaces). Binary resources are indivisible unit-demand resources, and each agent either allocated one unit of the resource or none. In empirical results, we observe that in both cases, the average allocations converge over time to optimal allocations.","Title: On the AIMD Algorithm Under Saturation Constraints.\nYear: 2017\n\nAbstract: One of the most successful distributed resource allocation algorithms to be deployed in industry is the Additive-Increase Multiplicative-Decrease (AIMD) algorithm of Jain and Chiu. This algorithm already underpins the transport layer of the internet, and is now starting to find application in new areas in the context of Smart Grid and Smart Transportation applications. A distinguishing feature of these latter application areas, when compared with the internet, is the need to modify AIMD to account for lower and upper bounds in the resource allocated to individual agents. Our objective in this note is to demonstrate that the dynamic system arising from AIMD in this extended form has system theoretic properties similar to the classical algorithm.","Title: On Charge Point Anxiety And The Sharing Economy\nYear: 2017\n\nAbstract: This paper addresses some of the issues surrounding the charging of electric vehicles (EVs) with a particular focus on charge points. We discuss the design and implementation of a charge point adapter. The key feature of the adapter is that it provides privately owned charge points with the opportunity to be rented to members of the public, resulting in additional charging opportunities for EVs. We present a number of use cases whereby the adapter is used to alleviate the demand for EV charging in an area that experiences a shortage of charge points, but where private, unused charge points are available.","Title: Leader and Leaderless Multi-Layer Consensus With State Obfuscation: An Application to Distributed Speed Advisory Systems.\nYear: 2018\n\nAbstract: Two new distributed speed advisory systems (SASs) are introduced in this paper. The systems implement consensus algorithms that guide a set of vehicles toward a common driving speed. A major innovation is that consensus is achieved over a multi-layer network, in which parallel network topologies of connected vehicles are superimposed. The reason for the use of these parallel networks is that, in t...","Title: On the control of agents coupled through shared resources.\nYear: 2018\n\nAbstract: We consider a control problem involving a number of agents coupled through multiple unit-demand resources. Such resources are indivisible and each agentu0027s consumption is modeled as a Bernoulli random variable. Controlling such agents in a probabilistic manner, subject to capacity constraints, is ubiquitous in smart cities. For instance, such agents can be humans are in a feedback loop---who respond to a price signal), or automated decision-support systems that strive toward system-level goals. In this paper, we consider both a single feedback loop corresponding to a single resource and multiple coupled feedback loops corresponding to multiple resources consumed by the same population of agents. For example, when a network of devices allocate resources to deliver a number of services, these services are coupled through capacity constraints on these resources. We present a new algorithm with basic guarantees of convergence and optimality, as well as an example illustrating its performance.","Title: A Non-Invasive Method for the Safe Interaction of Cities and Electric Vehicle Fleets.\nYear: 2018\n\nAbstract: Electric and hybrid vehicles are growing in popularity. While these vehicles produce less pollution, they also produce less audible noise, especially at lower speeds. This makes it harder for pedestrians and cyclists to detect an approaching vehicle. Thus, an additional system is required to detect electric and hybrid vehicles and alert pedestrians and cyclists of their whereabouts, especially while these vehicles are driving at low speeds in cities. This paper introduces one such method based on high frequency audio emissions that are present in EVs, which arise, for example, from the process of magnetostriction. Our method is tested experimentally using four different tests vehicles, and a preliminary EV detection algorithm is also presented.","Title: Distributed Ledger Technology, Cyber-Physical Systems, and Social Compliance.\nYear: 2018\n\nAbstract: This paper describes how distributed ledger technologies (DLTs) can be used to enforce social contracts and to orchestrate the behavior of agents trying to access a shared resource. The first part of this paper analyzes the advantages and disadvantages of using DLTs architectures to implement certain control systems in an Internet of Things (IoT) setting and then focuses on a specific type of DLT based on a directed acyclic graph. In this setting, we propose a set of delay differential equations to describe the dynamical behavior of the Tangle, an IoT-inspired directed acyclic graph designed for the cryptocurrency IOTA. The second part proposes an application of DLTs as a mechanism for dynamic deposit pricing, wherein the deposit of digital currency is used to orchestrate access to a network of shared resources. The pricing signal is used as a mechanism to enforce the desired level of compliance according to a predetermined set of rules. After presenting an illustrative example, we analyze the control system and provide sufficient conditions for the stability of the network.","Title: Communication-efficient Distributed Multi-resource Allocation.\nYear: 2018\n\nAbstract: In several smart city applications, multiple resources must be allocated among competing agents that are coupled through such shared resources and are constrained — either through limitations of communication infrastructure or privacy considerations. We propose a distributed algorithm to solve such distributed multi-resource allocation problems with no direct inter-agent communication. We do so by extending a recently introduced additive-increase multiplicative-decrease (AIMD) algorithm, which only uses very little communication between the system and agents. Namely, a control unit broadcasts a one-bit signal to agents whenever one of the allocated resources exceeds capacity. Agents then respond to this signal in a probabilistic manner. In the proposed algorithm, each agent makes decision of its resource demand locally and an agent is unaware of the resource allocation of other agents. In empirical results, we observe that the average allocations converge over time to optimal allocations.","Title: Context-Based Cyclist Intelligent Support: An Approach To E-Bike Control Based On Smartphone Sensors\nYear: 2018\n\nAbstract: Electrically assisted bicycles (e-bikes or pedelecs) have recently become popular as a means of personal transportation, particularly in cities. Pedelecs allow people to combine their muscular strength in varying proportions with the assistance of an electric engine. One of the challenges here is to determine the cyclist preferences, capabilities, and the context situation around the e-bike and, based on these, to make recommendations to the cyclist and also to control the degree of electrical assistance provided. The Smart Space concept is used here for context formation. The concept involves creation of a real-time model of the physical space that aids decision making about electrical engine utilization for the particular situation and generates a recommendation for the cyclist. An ontology-based publish/subscribe mechanism is used for information sharing in Smart Space.","Title: ISS Property with Respect to Boundary Disturbances for a Class of Riesz-Spectral Boundary Control Systems.\nYear: 2018\n\nAbstract: This paper deals with the establishment of Input-to-State Stability (ISS) estimates for infinite dimensional systems with respect to both boundary and distributed disturbances. First, a new approach is developed for the establishment of ISS estimates for a class of Riesz-spectral boundary control systems satisfying certain eigenvalue constraints. Second, a concept of weak solutions is introduced in order to relax the disturbances regularity assumptions required to ensure the existence of classical solutions. The proposed concept of weak solutions, that applies to a large class of boundary control systems which is not limited to the Riesz-spectral ones, provides a natural extension of the concept of both classical and mild solutions. Assuming that an ISS estimate holds true for classical solutions, we show the existence, the uniqueness, and the ISS property of the weak solutions.","Title: Distributed Ledger Technology for Smart Cities, the Sharing Economy, and Social Compliance.\nYear: 2018\n\nAbstract: This paper describes how distributed ledger technologies (DLTs) can be used to enforce social contracts and to orchestrate the behavior of agents trying to access a shared resource. The first part of this paper analyzes the advantages and disadvantages of using DLTs architectures to implement certain control systems in an Internet of Things (IoT) setting and then focuses on a specific type of DLT based on a directed acyclic graph. In this setting, we propose a set of delay differential equations to describe the dynamical behavior of the Tangle, an IoT-inspired directed acyclic graph designed for the cryptocurrency IOTA. The second part proposes an application of DLTs as a mechanism for dynamic deposit pricing , wherein the deposit of digital currency is used to orchestrate access to a network of shared resources. The pricing signal is used as a mechanism to enforce the desired level of compliance according to a predetermined set of rules. After presenting an illustrative example, we analyze the control system and provide sufficient conditions for the stability of the network.","Title: A New Take on Protecting Cyclists in Smart Cities.\nYear: 2018\n\nAbstract: Pollution in urban centers is becoming a major societal problem. While pollution is a concern for all urban dwellers, cyclists are one of the most exposed groups due to their proximity to vehicle tailpipes. Consequently, new solutions are required to help protect citizens, especially cyclists, from the harmful effects of exhaust-gas emissions. In this context, hybrid vehicles (HVs) offer new actua...","Title: Identification Of New Patterns In Urban Traffic Flows\nYear: 2018\n\nAbstract: Traffic flow pattern identification, as well as anomaly detection, is known to be an important component for traffic operations and control. Alongside classical applications, mainly, to improve the safety and the comfort of drivers, more recently there is a growing interest in gathering personalised route information to provide customised services. With this latter application in mind, in this paper we investigate the ability of simple macroscopic information (i.e., time varying junction turning probabilities) to identify changes in nominal urban traffic flows, most likely due to the occurrence of external events (e.g., road works or traffic congestions). Some preliminary results obtained with the use of a realistic mobility simulator are also illustrated and discussed, and some candidate applications are briefly outlined.","Title: Distributed Algorithms for Internet-of-Things enabled Prosumer Markets: A Control Theoretic Perspective.\nYear: 2018\n\nAbstract: Internet-of-Things (IoT) enables the development of sharing economy applications. In many sharing economy scenarios, agents both produce as well as consume a resource; we call them prosumers. A community of prosumers agrees to sell excess resource to another community in a prosumer market. In this chapter, we propose a control theoretic approach to regulate the number of prosumers in a prosumer community, where each prosumer has a cost function that is coupled through its time-averaged production and consumption of the resource. Furthermore, each prosumer runs its distributed algorithm and takes only binary decisions in a probabilistic way, whether to produce one unit of the resource or not and to consume one unit of the resource or not. In the proposed approach, prosumers do not explicitly exchange information with each other due to privacy reasons, but little exchange of information is required for feedback signals, broadcast by a central agency. In the proposed approach, prosumers achieve the optimal values asymptotically. Furthermore, the proposed approach is suitable to implement in an IoT context with minimal demands on infrastructure. We describe two use cases; community-based car sharing and collaborative energy storage for prosumer markets. We also present simulation results to check the efficacy of the algorithms.","Title: On Synchronization in Continuous-Time Networks of Nonlinear Nodes With State-Dependent and Degenerate Noise Diffusion.\nYear: 2019\n\nAbstract: In this paper, we present a generalization of a recent result on the almost sure consensus for networks affected by relative-state-dependent measurement noise. Specifically, we give two sufficient conditions for the synchronization of networks of diffusively coupled nonlinear nodes affected by certain state-dependent noise diffusion processes. We use this condition to study the onset of synchroniz...","Title: IOTA-based Directed Acyclic Graphs without Orphans.\nYear: 2019\n\nAbstract: Directed Acylic Graphs (DAGs) are emerging as an attractive alternative to traditional blockchain architectures for distributed ledger technology (DLT). In particular DAG ledgers with stochastic attachment mechanisms potentially offer many advantages over blockchain, including scalability and faster transaction speeds. However, the random nature of the attachment mechanism coupled with the requirement of protection against double-spend transactions leaves open the possibility that not all transactions will be eventually validated. Such transactions are said to be orphaned, and will never be validated. Our principal contribution is to propose a simple modification to the attachment mechanism for the Tangle (the IOTA DAG architecture). This modification ensures that all transactions are validated in finite time, and preserves essential features of the popular Monte-Carlo selection algorithm. In order to demonstrate these results we derive a fluid approximation for the Tangle (in the limit of infinite arrival rate) and prove that this fluid model exhibits the desired behavior. We also present simulations which validate the results for finite arrival rates.","Title: Derandomized Distributed Multi-resource Allocation with Little Communication Overhead.\nYear: 2018\n\nAbstract: We study a class of distributed optimization problems for multiple shared resource allocation in Internet-connected devices. We propose a derandomized version of an existing stochastic additive-increase and multiplicative-decrease (AIMD) algorithm. The proposed solution uses one bit feedback signal for each resource between the system and the Internet-connected devices and does not require inter-device communication. Additionally, the Internet-connected devices do not compromise their privacy and the solution does not dependent on the number of participating devices. In the system, each Internet-connected device has private cost functions which are strictly convex, twice continuously differentiable and increasing. We show empirically that the long-term average allocations of multiple shared resources converge to optimal allocations and the system achieves minimum social cost. Furthermore, we show that the proposed derandomized AIMD algorithm converges faster than the stochastic AIMD algorithm and both the approaches provide approximately same solutions.","Title: A Context-Aware E-Bike System to Reduce Pollution Inhalation While Cycling.\nYear: 2019\n\nAbstract: The effect of transport-related pollution on human health is fast becoming recognized as a major issue in cities worldwide. Cyclists, in particular, face great health risks, as they typically are most exposed to tail-pipe emissions. Four avenues are being explored to combat urban air pollution: 1) policy interventions such as outright bans on polluting vehicles, 2) embracing zero tailpipe emission...","Title: An Adaptive AIMD Congestion Control Protocol for Communication Networks\nYear: 2004\n\nAbstract: We present a new adaptive TCP protocol for the control of congestion in communication networks. The key innovative idea in our protocol is to combine results from Frobenius-Perron theory with online adaptation to realise a TCP variant that: (i) allocates the network pipe fairly amongst competing flows; (ii) coexists with other TCP variants; (iii) responds rapidly to changes in available bandwidth; and (iv) which strives to achieve a high data rate through the bottleneck link. When implemented, the new protocol requires only sender-side modification of the standard window congestion control scheme and is transparent to network buffers and network sources operating other TCP-variants. Results from the network simulator NS are presented to illustrate the key features of our scheme.","Title: R-Extreme Signalling For Congestion Control\nYear: 2016\n\nAbstract: In many smart city' applications, congestion arises in part due to the nature of signals received by individuals from a central authority. In the model of Mareek et al., each agent uses one out of multiple resources at each time instant. The per-use cost of a resource depends on the number of concurrent users. A central authority has up-to-date knowledge of the congestion across all resources and uses randomisation to provide a scalar or an interval for each resource at each time. In this paper, the interval to broadcast per resource is obtained by taking the minima and maxima of costs observed within a time window of length r, rather than by randomisation. We show that the resulting distribution of agents across resources also converges in distribution, under plausible assumptions about the evolution of the population over time.","Title: On the SPRification of Linear Descriptor Systems via Output Feedback\nYear: 2019\n\nAbstract: We consider input–output systems in descriptor form and ask when such systems can be rendered strictly positive real (SPR) via output feedback. Time- and frequency-domain conditions are given to determine when and how this is possible. In addition, a synthesis procedure for controller design is also derived. Together, the results provide a complete answer to when a linear descriptor system can be made SPR via output feedback, and provide a recipe for design of a feedback controller when one exists.","Title: A Hidden Markov Model For Route And Destination Prediction\nYear: 2018\n\nAbstract: We present a simple model and algorithm for predicting driver destinations and routes, based on the input of the latest road links visited as part of an ongoing trip. The algorithm may be used to predict any clusters previously observed in a driver's trip history. It assumes that the driver's historical trips are grouped into clusters sharing similar patterns. Given a new trip, the algorithm attempts to predict the cluster in which the trip belongs. The proposed algorithm has low temporal complexity. In addition, it does not require the transition and emission matrices of the Markov chain to be computed. Rather it relies on the frequencies of co-occurrences of road links and trip clusters. We validate the proposed algorithm against an experimental dataset. We discuss the success and convergence of the algorithm and show that our algorithm has a high prediction success rate.","Title: Recovering Markov Models from Closed-Loop Data.\nYear: 2019\n\nAbstract: Abstract Situations in which recommender systems are used to augment decision making are becoming prevalent in many application domains. Almost always, these prediction tools (recommenders) are created with a view to affecting behavioural change. Clearly, successful applications actuating behavioural change, affect the original model underpinning the predictor, leading to an inconsistency. This feedback loop is often not considered in standard machine learning techniques which rely upon machine learning/statistical learning machinery. The objective of this paper is to develop tools that recover unbiased user models in the presence of recommenders. More specifically, we assume that we observe a time series which is a trajectory of a Markov chain R modulated by another Markov chain S , i.e. the transition matrix of R is unknown and depends on the current state of S . The transition matrix of the latter is also unknown. In other words, at each time instant, S selects a transition matrix for R within a given set which consists of known and unknown matrices. The state of S , in turn, depends on the current state of R thus introducing a feedback loop. We propose an Expectation–Maximisation (EM) type algorithm, which estimates the transition matrices of S and R . Experimental results are given to demonstrate the efficacy of the approach.","Title: On the design of a decision engine for connected vehicles with an application to congestion management.\nYear: 2018\n\nAbstract: Vehicles are becoming connected entities. As a result, a likely scenario is that such entities might be literally bombarded with information from a multitude of devices. In this context, a key challenging requirement for both connected and autonomous vehicles is that they will need to become cognitive bodies, able to parse information and use only the pieces of information that are relevant to the vehicle in the context of a given journey. In order to address this fundamental requirement, a decision engine is presented in this paper. The engine makes it possible for the vehicle to understand which pieces of information are really relevant, and subsequently to process only those pieces of information. In order to illustrate the key features of our system, we show that it is possible to build upon the engine to develop a distributed traffic management system, and then we validate such a system via both conventional (numerical and SUMO-based) simulations and a Hardware-in-the-Loop (HIL) platform. Both the conventional simulations and the HIL validation showed that the engine can be effectively used to design a distributed traffic management system.","Title: A Distributed Markovian Parking Assist System\nYear: 2019\n\nAbstract: This paper proposes a congestion balancing parking guidance system that suggests to a driver a sequence of streets to follow around the desired destination with the aim to reduce the total distance that is travelled while searching for a free parking spot. The system requires only limited infrastructure information, and neither requires parking spaces to be instrumented, nor vehicles to communicate with each other. Specifically, the system utilizes parking vacancy information on each street. The system also accounts for the added cost of not finding a free space, which is typically expressed as the additional distance that needs to be travelled to find an available parking spot. To avoid local congestion, different drivers respond to different suggestions based on a probability distribution that considers the total distance that needs to be travelled. A mobility simulator is used to model the searching behaviors of vehicles for parking spaces with and without the smart parking algorithm and experimental results are provided using the road network of the city of Dublin, Ireland.","Title: Distributed Ledger Technology for IoT: Parasite Chain Attacks.\nYear: 2019\n\nAbstract: Directed Acyclic Graph (DAG) based Distributed Ledgers can be useful in a number of applications in the IoT domain. A distributed ledger should serve as an immutable and irreversible record of transactions, however, a DAG structure is a more complicated mathematical object than its blockchain counterparts, and as a result, providing guarantees of immutability and irreversibility is more involved. In this paper, we analyse a commonly discussed attack scenario known as a parasite chain attack for the IOTA Foundation DAG based ledger. We analyse the efficacy of IOTA core MCMC algorithm using a matrix model and present an extension which improves the ledger resistance to these attacks.","Title: A LMI condition for the Robustness of Linear Predictor Feedback with Respect to Time-Varying Input Delays.\nYear: 2019\n\nAbstract: This paper discusses the robustness of the predictor feedback in the case of an unknown time varying delay. Specifically, we study the stability of the closed-loop system when the predictor feedback is designed based on the knowledge of the nominal value of the time-varying delay. By resorting to an adequate Lyapunov-Krasovskii functional, we derive a LMI-based sufficient condition ensuring the asymptotic stability of the closed-loop system for small enough variations of the time-varying delay around its nominal value. These results are extended to the feedback stabilization of a class of diagonal infinite-dimensional boundary control systems in the presence of a time-varying delay in the boundary control input.","Title: Augmented Reality, Cyber-Physical Systems, and Feedback Control for Additive Manufacturing: A Review.\nYear: 2019\n\nAbstract: Our objective in this paper is to review the application of feedback ideas in the area of additive manufacturing. Both the application of feedback control to the 3D printing process and the application of feedback theory to enable users to interact better with machines are reviewed. Where appropriate, opportunities for future work are highlighted.","Title: On L∞ string stability of nonlinear bidirectional asymmetric heterogeneous platoon systems\nYear: 2019\n\nAbstract: This paper is concerned with the study of bidirectionally coupled platoon systems. The case considered is when the vehicles are heterogeneous and the coupling can be nonlinear and asymmetric. For such systems, a sufficient condition for L∞ string stability is presented. The effectiveness of our approach is illustrated via a numerical example, where it is shown how our result can be recast as an optimization problem, allowing to design the control protocol for each vehicle independently on the other vehicles and hence leading to a bottom-up approach for the design of string stable systems able to track a time-varying reference speed.","Title: Some stability tests for switched descriptor systems\nYear: 2019\n\nAbstract: In this paper we first derive some general Lyapunov based stability conditions for switched linear descriptor systems and illustrate them with a simple mechanical system. Next we develop simple conditions for specific classes of systems. In particular, we consider the important case when switching between a standard system and an index one descriptor system, and systems where switching occurs between an index one and an index two descriptor system. Examples are given to illustrate these results.","Title: Control Law Realification for the Feedback Stabilization of a Class of Diagonal Infinite-Dimensional Systems with Delay Boundary Control\nYear: 2019\n\nAbstract: Recently, a predictor feedback control strategy has been reported for the feedback stabilization of a class of infinite-dimensional Riesz-spectral boundary control systems exhibiting a finite number of unstable modes by means of a delay boundary control. Nevertheless, for real abstract boundary control systems exhibiting eigenstructures defined over the complex field, the direct application of suc...","Title: On DICE-free Smart Cities, Particulate Matter, and Feedback-Enabled Access Control.\nYear: 2019\n\nAbstract: The link between transport related emissions and human health is a major issue for city municipalities worldwide. PM emissions from exhaust and non-exhaust sources are one of the main worrying contributors to air-pollution. In this paper, we challenge the notion that a ban on DICE vehicles will result in clean and safe air in our cities, since emissions from tyres and other non-exhaust sources are expected to increase in the near future. To this end, we present data from the city of Dublin that document that the current amount of tyre-related PM emissions in the city might already be above or close to the levels deemed safe by the World Health Organization. As a solution to this problem, we present a feedback-enabled distributed access control mechanism and ride-sharing scheme to limit the amount of vehicles in a city and therefore maintain the amount of transport-related PM to safe levels. As shown in our simulations, our mechanism successfully restricts the number of cars in a city while ensuring fair access for its users.","Title: Hysteresis-based supervisory control with application to non-pharmaceutical containment of COVID-19\nYear: 2021\n\nAbstract: The recent COVID-19 outbreak has motivated an extensive development of non-pharmaceutical intervention policies for epidemics containment. While a total lockdown is a viable solution, interesting policies are those allowing some degree of normal functioning of the society, as this allows a continued, albeit reduced, economic activity and lessens the many societal problems associated with a prolonged lockdown. Recent studies have provided evidence that fast periodic alternation of lockdown and normal-functioning days may effectively lead to a good trade-off between outbreak abatement and economic activity. Nevertheless, the correct number of normal days to allocate within each period in such a way to guarantee the desired trade-off is a highly uncertain quantity that cannot be fixed a priori and that must rather be adapted online from measured data. This adaptation task, in turn, is still a largely open problem, and it is the subject of this work. In particular, we study a class of solutions based on hysteresis logic. First, in a rather general setting, we provide general convergence and performance guarantees on the evolution of the decision variable. Then, in a more specific context relevant for epidemic control, we derive a set of results characterizing robustness with respect to uncertainty and giving insight about how a priori knowledge about the controlled process may be used for fine-tuning the control parameters. Finally, we validate the results through numerical simulations tailored on the COVID-19 outbreak.","Title: Integral action for setpoint regulation control of a reaction–diffusion equation in the presence of a state delay\nYear: 2021\n\nAbstract: This paper is concerned with the regulation control of a one-dimensional reaction–diffusion equation in the presence of a state-delay in the reaction term. The objective is to achieve the PI regulation of the right Dirichlet trace with a command selected as the left Dirichlet trace. The control design strategy consists of the design of a PI controller on a finite dimensional truncated model obtained by spectral reduction. By an adequate selection of the number of modes of the original infinite-dimensional system, we show that the proposed control design procedure achieves both the exponential stabilization of the original infinite-dimensional system as well as the setpoint regulation of the right Dirichlet trace.","Title: Access Control in Adversarial Environments for IoT-oriented Distributed Ledgers\nYear: 2021\n\nAbstract: The surge of Internet of Things (IoT) applications requires distributed systems capable of securely exchanging messages and immutably recording data. While traditional blockchain architectures were not designed with IoT in mind, more recent Distributed Ledger Technologies (DLTs), which are not based on proof of work, can be considered as a solution to deal with the above requirements. However, wit...","Title: Secure Access Control for DAG-Based Distributed Ledgers\nYear: 2022\n\nAbstract: Access control is a fundamental component of the design of distributed ledgers, influencing many aspects of their functionality, such as fairness, efficiency, traditional notions of network security, and adversarial attacks such as Denial-of-Service (DoS) attacks.\n<xref ref-type=\"fn\" rid=\"fn1\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><sup>1</sup></xref>\n In this work, we consider the security of a recently proposed access control protocol for directed acyclic graph-based distributed ledgers. We present a number of attack scenarios and potential vulnerabilities of the protocol and introduce a number of additional features which enhance its resilience. Specifically, a blacklisting algorithm, which is based on a reputation-weighted threshold, is introduced to handle both spamming and multirate malicious attackers. A solidification request component is also introduced to ensure the fairness and consistency of the network in the presence of attacks. Finally, a timestamp component is also introduced to maintain the consistency of the network in the presence of multirate attackers. Simulations to illustrate the efficacy and robustness of the revised protocol are also presented.","Title: Pitchfork-bifurcation-based competitive and collaborative control of an E-bike system\nYear: 2022\n\nAbstract: This paper is concerned with the design of a human-in-the-loop system for deployment on a smart pedelec (e-bike). From the control-theoretic perspective, the goal is not only to use the power assistance of the e-bike to reject disturbances along the route but also to manage the possibly competitive interactions between a human and the motor intervention. Managing the competitive/cooperative nature of the interactions is crucial for applications in which we wish to control physical aspects of the cycling behavior (e.g. heart rate and breathing rate). The basis of the control is a pitchfork bifurcation system, modeling the interactions, augmented using ideas from gain-scheduling. In vivo experiments have been conducted, showing the effectiveness of the proposed control strategy.","Title: Electric Vehicle Ensembles for Quality of Service Based Mitigation of Renewable Production Risk\nYear: 2022\n\nAbstract: While intermittent renewable power generation in the form of wind and solar PV has become a significant presence on the worlds electricity grids, the intermittency associated with this power supply introduces uncertainty into the grid operators task of matching supply with demand. A consequence of this intermittency is the large costs that accrue when supply is lower than forecasted and this cost ..."],"string":"[\n \"Title: A positive systems model of TCP-like congestion control: asymptotic results\\nYear: 2006\\n\\nAbstract: We study communication networks that employ drop-tail queueing and Additive-Increase Multiplicative-Decrease (AIMD) congestion control algorithms. It is shown that the theory of nonnegative matrices may be employed to model such networks. In particular, important network properties, such as: 1) fairness; 2) rate of convergence; and 3) throughput, can be characterized by certain nonnegative matrices. We demonstrate that these results can be used to develop tools for analyzing the behavior of AIMD communication networks. The accuracy of the models is demonstrated by several NS studies.\",\n \"Title: Trading link utilization for queueing delays: An adaptive approach\\nYear: 2010\\n\\nAbstract: Understanding the relationship between queueing delays and link utilization for general traffic conditions is an important open problem in networking research. Difficulties in understanding this relationship stem from the fact that it depends on the complex nature of arriving traffic and the problems associated with modelling such traffic. Existing AQM schemes achieve a ''low delay'' and ''high utilization'' by responding early to congestion without considering the exact relationship between delay and utilization. However, in the context of exploiting the delay/utilization tradeoff, the optimal choice of a queueing scheme's control parameter depends on the cost associated with the relative importance of queueing delay and utilization. The optimal choice of control parameter is the one that maximizes a benefit that can be defined as the difference between utilization and cost associated with queuing delay. We present two practical algorithms, Optimal Drop-Tail (ODT) and Optimal BLUE (OB), that are designed with a common performance goal: namely, maximizing this benefit. Their novelty lies in fact that they maximize the benefit in an online manner, without requiring knowledge of the traffic conditions, specific delay-utilization models, nor do they require complex parameter estimation. Packet level ns2 simulations are given to demonstrate the efficacy of the proposed algorithms and the framework in which they are designed.\",\n \"Title: Preservation of piecewise-linear Lyapunov function under Padé discretization\\nYear: 2011\\n\\nAbstract: In this paper we show that certain piecewise-linear Lyapunov functions are preserved for LTI systems under Padé approximations. In particular, we present a simple method to find a piecewise-linear Lyapunov function that is so preserved under the Padé discretization of any order and sampling time. This result may be of interest in the discretisation of switched linear systems for both simulation and control design.\",\n \"Title: Fully decentralized emulation of best-effort and processor sharing queues\\nYear: 2008\\n\\nAbstract: Control of large distributed cloud-based services is a challenging problem. The Distributed Rate Limiting (DRL) paradigm was recently proposed as a mechanism for tackling this problem. The heuristic nature of existing DRL solutions makes their behavior unpredictable and analytically untractable. In this paper we treat the DRL problem in a mathematical framework and propose two novel DRL algorithms that exhibit good and predictable performance. The first algorithm Cloud Control with Constant Probabilities (C3P) solves the DRL problem in best effort environments, emulating the behavior of a single best-effort queue in a fully distributed manner. The second problem we approach is the DRL in processor sharing environments. Our algorithm, Distributed Deficit Round Robin (D2R2), parameterized by parameter α, converges to a state that is, at most, O(1/α) away from the exact emulation of centralized processor sharing queue. The convergence and stability properties are fully analyzed for both C3P and D2R2. Analytical results are validated empirically through a number of representative packet level simulations. The closed-form nature of our results allows simple design rules which, together with extremely low communication overhead, makes the presented algorithms practical and easy to deploy.\",\n \"Title: Quadratic And Copositive Lyapunov Functions And The Stability Of Positive Switched Linear Systems\\nYear: 2007\\n\\nAbstract: We present some new results concerning the stability of positive switched linear systems. In particular, we present a necessary and suffcient condition for the existence of copositive linear Lyapunov functions for switched systems with two constituent linear time-invariant (LTI) systems. We also extend some recent results on quadratic stability for positive switched linear systems.\",\n \"Title: Nonlinear AIMD Congestion Control and Contraction Mappings\\nYear: 2007\\n\\nAbstract: This papers analyzes a class of nonlinear additive-increase multiplicative-decrease (AIMD) protocols that are widely deployed in communication networks. It is demonstrated that the use of these protocols guarantees that the system has a unique stable outcome to which it converges geometrically under all starting points. The development is based on a contraction argument and the derivation of explicit bounds on the contraction coefficient of corresponding operators in terms of the network parameters. In particular, bounds on the corresponding rate of convergence are obtained, improving upon known bounds for standard (linear) AIMD networks.\",\n \"Title: A Nonconservative LMI Condition for Stability of Switched Systems With Guaranteed Dwell Time.\\nYear: 2012\\n\\nAbstract: Ensuring stability of switched linear systems with a guaranteed dwell time is an important problem in control systems. Several methods have been proposed in the literature to address this problem, but unfortunately they provide sufficient conditions only. This technical note proposes the use of homogeneous polynomial Lyapunov functions in the non-restrictive case where all the subsystems are Hurwitz, showing that a sufficient condition can be provided in terms of an LMI feasibility test by exploiting a key representation of polynomials. Several properties are proved for this condition, in particular that it is also necessary for a sufficiently large degree of these functions. As a result, the proposed condition provides a sequence of upper bounds of the minimum dwell time that approximate it arbitrarily well. Some examples illustrate the proposed approach.\",\n \"Title: A Scaling And Squaring Method For The Discretisation Of Positive Switched Systems\\nYear: 2011\\n\\nAbstract: In this paper we present a new method for approximating the matrix exponential of a Metzler matrix. This method is useful in discretising switched positive systems. In particular, the method preserves both linear and quadratic stability of the original continuous time system, as well as positivity of states starting for initial conditions in the positive orthant. The usefulness of the method is highlighted by illustrating some of the drawbacks of Pade approximations when applied to positive linear systems.\",\n \"Title: An extension of the KYP-lemma for the design of state-dependent switching systems with uncertainty.\\nYear: 2013\\n\\nAbstract: We consider the problem of designing state-dependent linear switching systems subject to parameter uncertainty. The switching rule is governed by a fixed partition of the state-space, and the parameter uncertainty appears in the matrices which determine the resulting dynamics. We derive a KYP-like lemma that can be used to design such systems in a manner that guarantees quadratic stability, for an arbitrary number of independent switching rules, each with its own switching region and its own domain of parameter uncertainty. Examples are given to illustrate the usefulness of our result.\",\n \"Title: On Nonlinear Aimd Congestion Control For High-Speed Networks\\nYear: 2006\\n\\nAbstract: This papers analyzses a class of nonlinear positive systems that model the dynamics of nonlinear additive-increase multiplicative-decrease (AIMD) protocols. The system class covers a range of protocols that are currently used in real communication networks, such as standard TCP, and recent proposals for congestion control protocols such as Scalable TCP.\",\n \"Title: On The Fair Coexistence Of Loss- And Delay-Based Tcp\\nYear: 2009\\n\\nAbstract: Delay-based TCP variants continue to attract a large amount of attention in the networking community. Potentially, they offer the possibility to efficiently use network resources while at the same time achieving low queueing delay and virtually zero packet loss. One major impediment to the deployment of delay-based TCP variants is their inability to coexist fairly with standard loss-based TCP. In this paper we propose a simple strategy to make the fair coexistence possible and to ensure that delay-based flows will revert back to the delay-based operation when loss-based flows are no longer present. Analytical and ns-2 simulation results are presented to validate the proposed algorithm.\",\n \"Title: A novel pattern classification scheme using the Baker's map\\nYear: 2003\\n\\nAbstract: We demonstrate a novel application of nonlinear systems in the design of pattern classification systems. We show that pattern classification systems can be designed based upon training algorithms designed to control the qualitative behaviour of a nonlinear system. Our paradigm is illustrated by means of a simple chaotic system—the Baker's map. Algorithms for training the system are presented and examples are given to illustrate the operation and learning of the system for pattern classification tasks.\",\n \"Title: A methodology for the design of robust rollover prevention controllers for automotive vehicles: Part 1-Differential braking\\nYear: 2006\\n\\nAbstract: In this paper, we apply recent results from robust control to the problem of rollover prevention in automotive vehicles. Specifically, we exploit the results of Pancake, Corless and Brockman, which provide controllers to robustly guarantee that the peak values of the performance outputs of an uncertain system do not exceed certain values. We introduce a new measure of performance for rollover prevention, the load transfer ratio LTRd, and design differential-braking-based rollover controllers to keep the value of this quantity below a certain level; we also obtain controllers which yield robustness to variations in vehicle speed. We present numerical simulations to demonstrate the efficacy of our controllers\",\n \"Title: On the interpretation and identification of dynamic Takagi-Sugeno fuzzy models\\nYear: 2000\\n\\nAbstract: Dynamic Takagi-Sugeno fuzzy models are not always easy to interpret, in particular when they are identified from experimental data. It is shown that there exists a close relationship between dynamic Takagi-Sugeno fuzzy models and dynamic linearization when using affine local model structures, which suggests that a solution to the multiobjective identification problem exists. However, it is also shown that the affine local model structure is a highly sensitive parametrization when applied in transient operating regimes. Due to the multiobjective nature of the identification problem studied here, special considerations must be made during model structure selection, experiment design, and identification in order to meet both objectives. Some guidelines for experiment design are suggested and some robust nonlinear identification algorithms are studied. These include constrained and regularized identification and locally weighted identification. Their usefulness in the present context is illustrated by examples\",\n \"Title: On linear co-positive Lyapunov functions for sets of linear positive systems\\nYear: 2009\\n\\nAbstract: In this paper we derive necessary and sufficient conditions for the existence of a common linear co-positive Lyapunov function for a finite set of linear positive systems. Both the state dependent and arbitrary switching cases are considered. Our results reveal an interesting characterisation of “linear” stability for the arbitrary switching case; namely, the existence of such a linear Lyapunov function can be related to the requirement that a number of extreme systems are Metzler and Hurwitz stable. Examples are given to illustrate the implications of our results.\",\n \"Title: Deterministic and stochastic convergence properties of AIMD algorithms with nonlinear back-off functions\\nYear: 2012\\n\\nAbstract: In this paper we establish basic stability results for a class of nonlinear AIMD (additive-increase multiplicative-decrease) algorithms. We consider networks in which the nonlinearity enters through the multiplicative-decrease mechanism. In particular, where the multiplicative-decrease function depends in a nonlinear fashion on the achieved rate. For synchronized deterministic networks, we establish stability and convergence results. For non-synchronized stochastic networks, basic convergence results are also established. In particular, we give conditions for the existence of a unique invariant stationary distribution, and conditions under which time- and ensemble-averages converge to the same unique value (irrespective of initial conditions).\",\n \"Title: Distributed Probabilistic Synchronization Algorithms for Communication Networks\\nYear: 2008\\n\\nAbstract: In this paper, we present a probabilistic synchronization algorithm whose convergence properties are examined using tools of row-stochastic matrices. The proposed algorithm is particularly well suited for wireless sensor network applications, where connectivity is not guaranteed at all times, and energy efficiency is an important design consideration. The tradeoff between the convergence speed and the energy use is studied.\",\n \"Title: How expensive is link utilization?\\nYear: 2007\\n\\nAbstract: Understanding the relationship between queueing delays and link utilization for general traffic conditions is an important open problem in networking research. Difficulties in understanding this relationship stem from the fact that it depends on the complex nature of arriving traffic and the problems associated with modelling such traffic. Existing AQM schemes achieve a \\\"low delay\\\" and \\\"high utilization\\\" by responding early to congestion without considering the exact relationship between delay and utilization. However, in the context of exploiting the delay/utilization tradeoff, the optimal choice of a queueing scheme's control parameter depends on the cost associated with the relative importance of queueing delay and utilization. The optimal choice of control parameter is the one that maximizes a benefit that can be defined as the difference between utilization and cost associated with queuing delay. We present a generic algorithm Optimal Delay-Utilization control of t (ODU-t) that is designed with a performance goal of maximizing this benefit. Its novelty lies in fact that it maximizes the benefit in an online manner, without requiring knowledge of the traffic conditions, specific delay-utilization models, nor does it require complex parameter estimation. Moreover, other performance metrics like loss rate or jitter can be directly incorporated into the optimization framework as well. Packet level ns2 simulations are given to demonstrate the behavior of the proposed algorithm.\",\n \"Title: Beyond CHOKe: stateless fair queueing\\nYear: 2007\\n\\nAbstract: Making drop decisions to enforce the max-min fair resource allocation in a network of standard TCP flows without any explicit state information is a challenging problem. Here we propose a solution to this problem by developing a suite of stateless queue management schemes that we refer to as Multi-Level Comparison with index l (MLC(l)). We show analytically, using a Markov chain model, that for an arbitrary network topology of standard TCP flows and queues employing MLC(l), the resource allocation converges to max-min fair as l increases. The analytical findings are verified experimentally using packet level ns2 simulations.\",\n \"Title: Convex cones, lyapunov functions, and the stability of switched linear systems\\nYear: 2003\\n\\nAbstract: Recent research on switched and hybrid systems has resulted in a renewed interest in determining conditions for the existence of a common quadratic Lyapunov function for a finite number of stable LTI systems. While efficient numerical solutions to this problem have existed for some time, compact analytical conditions for determining whether or not such a function exists for a finite number of systems have yet to be obtained. In this paper we present a geometric approach to this problem. By making a simplifying assumption we obtain a compact time-domain condition for the existence of such a function for a pair of LTI systems. We show a number of new and classical Lyapunov results can be obtained using our framework. In particular, we demonstrate that our results can be used to obtain compact time-domain versions of the SISO Kalman-Yacubovich-Popov lemma, the Circle Criterion, and stability multiplier criteria. Finally, we conclude by posing a number of open questions that arise as a result of our approach.\",\n \"Title: Stability Criteria for Switched and Hybrid Systems.\\nYear: 2007\\n\\nAbstract: The study of the stability properties of switched and hybrid systems gives rise to a number of interesting and challenging mathematical problems. The objective of this paper is to outline some of these problems, to review progress made in solving them in a number of diverse communities, and to review some problems that remain open. An important contribution of our work is to bring together material from several areas of research and to present results in a unified manner. We begin our review by relating the stability problem for switched linear systems and a class of linear differential inclusions. Closely related to the concept of stability are the notions of exponential growth rates and converse Lyapunov theorems, both of which are discussed in detail. In particular, results on common quadratic Lyapunov functions and piecewise linear Lyapunov functions are presented, as they represent constructive methods for proving stability and also represent problems in which significant progress has been made. We also comment on the inherent difficulty in determining stability of switched systems in general, which is exemplified by NP-hardness and undecidability results. We then proceed by considering the stability of switched systems in which there are constraints on the switching rules, through both dwell-time requirements and state-dependent switching laws. Also in this case the theory of Lyapunov functions and the existence of converse theorems are reviewed. We briefly comment on the classical Lur'e problem and on the theory of stability radii, both of which contain many of the features of switched systems and are rich sources of practical results on the topic. Finally we present a list of questions and open problems which provide motivation for continued research in this area.\",\n \"Title: An experimental evaluation of distributed rate limiting for cloud computing applications\\nYear: 2010\\n\\nAbstract: Pricing and load distribution in a cloud are difficult problems. In order to recover the construction costs of the data center, the owner must endeavour to have high utilization while maintaining performance levels for the users. Distributed Rate Limiting (DRL) is a mechanism that can be used to attack this problem. A mathematical framework and the convergence and stability properties of two DRL algorithms were examined in previous work. In this paper we build upon that work by evaluating the performance of these algorithms on a testbed against the results of a simulation carried out in previous work. We also evaluate the algorithms resilience to failure and propose the good-neighbours enhancement to improve its performance.\",\n \"Title: Modelling TCP Throughput and Fairness\\nYear: 2004\\n\\nAbstract: Since TCP traffic is elastic, a fundamental issue is the behaviour of multiple TCP flows competing for bandwidth on a shared link. Motivated by the ubiquity of drop-tail queueing in current networks, our focus in this paper is on developing analytic models suited to characterising the throughput and fairness of competing TCP flows in drop-tail environments. Building on recent ideas from the theory of positive linear systems, we obtain simple, insightful closed-form expressions for throughput and fairness. The accuracy of these expressions is confirmed in extensive simulations across a range of network conditions. In particular, they are found to provide accurate estimate of mean fairness and throughput even when flows are not synchronised.\",\n \"Title: Analysis and design of AIMD congestion control algorithms in communication networks\\nYear: 2005\\n\\nAbstract: We present a model of a network of synchronised sources operating additive increase multiplicative decrease (AIMD) congestion control algorithms. We show: (i) that networks of such devices in the presence of a drop-tail bottleneck buffer may be modelled as a positive linear system; (ii) that such networks possess a unique stationary point; and (iii) that this stationary point is globally exponentially stable. We use these results to establish conditions for the fair co-existence of traffic in networks employing heterogeneous AIMD algorithms and to design a new protocol for operation over high-speed and long-distance links.\",\n \"Title: A control design method for a class of switched linear systems\\nYear: 2009\\n\\nAbstract: In this note we consider the stability properties of a system class that arises in the control design problem of switched linear systems. The control design we are studying is based on a classical pole-placement approach. We analyse the stability of the resulting switched system and develop analytic conditions which reduce the complexity of the stability problem. We further consider two special cases for which strongly simplified conditions are obtained that support the analytic controller design.\",\n \"Title: Load balancing vs. distributed rate limiting: an unifying framework for cloud control\\nYear: 2009\\n\\nAbstract: With the expansion of cloud-based services, the question as to how to control usage of such large distributed systems has become increasingly important. Load balancing (LB), and recently proposed distributed rate limiting (DRL) have been used independently to reduce costs and to fairly allocate distributed resources. In this paper we propose a new mechanism for cloud control that unifies the use of LB and DRL: LB is used to minimize the associated costs and DRL makes sure that the resource allocation is fair. From an analytical standpoint, modelling the dynamics of DRL in dynamic workloads (resulting from LB cost-minimization scheme) is a challenging problem. Our theoretical analysis yields a condition that ensures convergence to the desired working regime. Analytical results are then validated empirically through several illustrative simulations. The closed-form nature of our result also allows simple design rules which, together with extremely low computational and communication overhead, makes the presented algorithm practical and easy to deploy.\",\n \"Title: Preservation of common quadratic Lyapunov functions and Padé approximations\\nYear: 2010\\n\\nAbstract: It is well known that the bilinear transform, or first order diagonal Padé approximation to the matrix exponential, preserves quadratic Lyapunov functions between continuous-time and corresponding discrete-time linear time invariant (LTI) systems, regardless of the sampling time. It is also well known that this mapping preserves common quadratic Lyapunov functions between continuous-time and discrete-time switched systems. In this note we show that while diagonal Padé approximations do not in general preserve other types of Lyapunov functions (or even stability), it is true that diagonal Padé approximations of the matrix exponential, of any order and sampling time, preserve quadratic stability. A consequence of this result is that the quadratic stability of switched systems is robust with respect to certain discretization methods.\",\n \"Title: Optimal distributed power generation for thermal and electrical scheduling in a microgrid\\nYear: 2013\\n\\nAbstract: This paper illustrates stochastic distributed algorithms that optimally share the electrical and thermal power generation task among the several Distributed Energy Resources (DERs) within a microgrid. We borrow certain concepts from communication network theory, namely Additive-Increase-Multiplicative-Decrease (AIMD) algorithms, which are known to be convenient in terms of communication requirements and network efficiency. We adapt them to minimise a cost utility function of interest in the framework of smart grids. We then implement the AIMD utility optimisation strategies in a realistic power network simulation in Matlab-OpenDSS environment, and we show the performance of the proposed algorithms in achieving thermal and electrical power balancing1.\",\n \"Title: Synthesis Of Piecewise-Linear Chaotic Maps: Invariant Densities, Autocorrelations, And Switching\\nYear: 2008\\n\\nAbstract: In this paper, we give a review of the Inverse Frobenius-Perron problem (IFPP): how to create chaotic maps with desired invariant densities. After describing some existing methods for solving the IFPP, we present a new and simple matrix method of doing this. We show how the invariant density and the autocorrelation properties of the maps can be controlled independently. We also give some fundamental results on switching between a number of different chaotic maps and the effect this has on the overall invariant density of the system. The invariant density of the switched system can be controlled by varying the probabilities of choosing each individual map. Finally, we present an interesting application of the matrix method to image generation, by synthesizing a two-dimensional map, which when iterated, generates a well-known image.\",\n \"Title: A design methodology for switched discrete time linear systems with applications to automotive roll dynamics control\\nYear: 2008\\n\\nAbstract: In this paper we consider the asymptotic stability of a class of discrete-time switching linear systems, where each of the constituent subsystems is Schur stable. We first present an example to motivate our study, which illustrates that the bilinear transform does not preserve the stability of a class of switched linear systems. Consequently, continuous time stability results cannot be transformed to discrete time analogs using this transformation. We then present a subclass of discrete-time switching systems that arise frequently in practical applications. We prove that global attractivity for this subclass can be obtained without requiring the existence of a common quadratic Lyapunov function (CQLF). Using this result, we present a synthesis procedure to construct switching stabilizing controllers for an automotive control problem, which is related to the stabilization of a vehicle’s roll dynamics subject to switches in the center of gravitys (CG) height.\",\n \"Title: On Optimality Criteria for Reverse Charging of Electric Vehicles\\nYear: 2014\\n\\nAbstract: Ever increasing expectations regarding the penetration level of electric vehicles (EVs) are driving several areas of research related to EV charging. One topic of interest treats EVs not only as controllable loads but also as storage systems, which can be used to mitigate the load on the grid during peak times by offering power. This is known as vehicle to grid (V2G). Since returning energy to the grid affects mobility patterns, V2G has an associated environmental cost. In this paper, to investigate this issue, we formulate the problem of returning electrical load to the grid as an optimization whose goal is to return the desired energy in a fashion that minimizes the cost on the environment. We show that this optimization is highly complex, and in some circumstances, the cost of V2G can be prohibitive.\",\n \"Title: Modelling TCP congestion control dynamics in drop-tail environments\\nYear: 2007\\n\\nAbstract: In this paper we study communication networks that employ drop-tail queueing and additive-increase multiplicative-decrease (AIMD) congestion control algorithms. We show that the theory of non-negative matrices may be employed to model such networks and to derive basic theorems concerning their behaviour.\",\n \"Title: A Numerical Technique for Stability Analysis of Linear Switched Systems\\nYear: 2004\\n\\nAbstract: Summary In this report the ray-gridding approach, a new numerical technique for the stability analysis of linear switched systems is presented. It is based on uniform partitions of the state-space in terms of ray directions which allow reflnable families of polytopes of adjustable complexity to be examined for invariance. In this framework the existence of a polyhedral Lyapunov function that is common to a family of asymptotically stable subsystems can be checked e-ciently via simple iterative algorithms. The technique can be used to prove the stability of switched linear systems, classes of linear time- varying systems and Linear Difierential Inclusions. We also present preliminary results on two other related problems; namely, the existence of stabilis- ing switching sequences for a switched system constructed from a family of unstable linear subsystems\",\n \"Title: A result on second order nonlinear operators arising in high-speed networking applications\\nYear: 2009\\n\\nAbstract: We consider the behaviour of a class of nonlinear difference equations that arise in networks employing congestion control protocols. For a class of such systems we show that trajectories, experiencing the same set of congestion notifications, but starting at different initial conditions, converge exponentially to each other.\",\n \"Title: On a class of generalized eigenvalue problems and equivalent eigenvalue problems that arise in systems and control theory\\nYear: 2011\\n\\nAbstract: Systems and control theory has long been a rich source of problems for the numerical linear algebra community. In many problems, conditions on analytic functions of a complex variable are usually evaluated by solving a special generalized eigenvalue problem. In this paper we develop a general framework for studying such problems. We show that for these problems, solutions can be obtained by either solving a generalized eigenvalue problem, or by solving an equivalent eigenvalue problem. A consequence of this observation is that these problems can always be solved by finding the eigenvalues of a Hamiltonian (or discrete-time counterpart) matrix, even in cases where an associated Hamiltonian matrix, cannot (normally) be defined. We also derive a number of new compact tests for determining whether or not a transfer function matrix is strictly positive real. These tests, which are of independent interest due to the fact that many problems can be recast as SPR problems, are defined even in the case when the matrix D+D^* is singular, and can be formulated without requiring inversion of the system matrix A.\",\n \"Title: Stratus: Load Balancing the Cloud for Carbon Emissions Control.\\nYear: 2013\\n\\nAbstract: Large public cloud infrastructure can utilise power which is generated by a multiplicity of power plants. The cost of electricity will vary among the power plants and each will emit different amounts of carbon for a given amount of energy generated. This infrastructure services traffic that can come from anywhere on the planet. It is desirable, for latency purposes, to route the traffic to the dat...\",\n \"Title: Classical Results on the Stability of Linear Time-Invariant Systems, and the Schwarz Form.\\nYear: 2014\\n\\nAbstract: The paper deals with the classical results of Routh and Hurwitz, Biehler and Kharitonov, concerning the stability of a linear time invariant differential equation. It is shown that these results follow directly from a Schwarz matrix representation of stable systems.\",\n \"Title: Preservation of quadratic stability under various common approximate discretization methods.\\nYear: 2014\\n\\nAbstract: In this paper we prove the following result. If A is a Hurwitz matrix and f is a rational function that maps the open left half of the complex plane into the open unit disc, then any Hermitian matrix P>0 which is a Lyapunov matrix for A (that is, PA+A∗P<0) is also a Stein matrix for f(A) (that is, f(A)∗Pf(A)−P<0).\",\n \"Title: On the quadratic stability of switched linear systems associated with symmetric transfer function matrices.\\nYear: 2014\\n\\nAbstract: In this paper we give necessary and sufficient conditions for weak and strong quadratic stability of a class of switched linear systems consisting of two subsystems, associated with symmetric transfer function matrices. These conditions can simply be tested by checking the eigenvalues of the product of two subsystem matrices. This result is an extension of the result by Shorten and Narendra for strong quadratic stability, and the result by Shorten et al. on weak quadratic stability for switched linear systems. Examples are given to illustrate the usefulness of our results.\",\n \"Title: Plug-and-Play Distributed Algorithms for Optimized Power Generation in a Microgrid.\\nYear: 2014\\n\\nAbstract: This paper introduces distributed algorithms that share the power generation task in an optimized fashion among the several Distributed Energy Resources (DERs) within a microgrid. We borrow certain concepts from communication network theory, namely Additive-Increase-Multiplicative-Decrease (AIMD) algorithms, which are known to be convenient in terms of communication requirements and network effici...\",\n \"Title: A-stable Padé approximations and quadratic stability\\nYear: 2013\\n\\nAbstract: In this paper we prove that all A-stable Padé approximations for the matrix exponential preserve common quadratic Lyapunov functions for switched linear systems.\",\n \"Title: Stability of a class of switched descriptor systems\\nYear: 2013\\n\\nAbstract: In this paper we use the dimensionality reduction result from [1] for linear descriptor systems to derive stability conditions for special classes of switched descriptor systems.\",\n \"Title: A Note on Discretization of Sparce Linear Systems.\\nYear: 2012\\n\\nAbstract: In this paper a modified Euler transformation is introduced and studied. The main merit of this transformation is to outperform stability preservation (with respect to the traditional Euler transformation) besides preserving the matrix sparseness. This is particular appealing in the analysis of positive systems since it is shown that stability is preserved independent of the sampling period. A brief collection of results for switched systems has been also provided.\",\n \"Title: Delay-Tolerant Stochastic Algorithms for Parking Space Assignment\\nYear: 2014\\n\\nAbstract: This paper introduces and illustrates some novel stochastic policies that assign parking spaces to cars looking for an available parking space. We analyze in detail both the main features of a single park, i.e., how a car could conveniently decide whether to try its luck at that parking lot or try elsewhere, and the case when more parking lots are available, and how to choose the best one. We discuss the practical requirements of the proposed strategies in terms of infrastructure technology and vehicles' equipment and the mathematical properties of the proposed algorithms in terms of robustness against delays, stability, and reliability. Preliminary results obtained from simulations are also provided to illustrate the feasibility and the potential of our stochastic assignment policies.\",\n \"Title: On the Dynamics of TCP's Higher Moments\\nYear: 2007\\n\\nAbstract: In this paper we extend a recently derived positive systems model for TCP to capture the dynamics of TCP's higher order moments in drop-tail environments. Experimental results are given to illustrate the accuracy of our model\",\n \"Title: On Queue Provisioning, Network Efficiency and the Transmission Control Protocol\\nYear: 2007\\n\\nAbstract: In this paper, we propose a sender side modification to TCP to accommodate small network buffers. We exploit the fact that the manner in which network buffers are provisioned is intimately related to the manner in which TCP operates. However, rather than designing buffers to accommodate the TCP AIMD algorithm, as is the traditional approach in network design, we suggest simple modifications to the AIMD algorithm to accommodate buffers of any size in the network. We demonstrate that networks with small buffers can be designed that transport TCP traffic in an efficient manner while retaining fairness and friendliness with standard TCP traffic.\",\n \"Title: On AIMD Congestion Control in Multiple Bottleneck Networks\\nYear: 2007\\n\\nAbstract: We consider a linear algebraic model of the Additive-Increase Multiplicative-Decrease congestion control algorithm and present results on average fairness and convergence for multiple bottleneck networks. Results are presented for networks of both long-lived and short-lived flows.\",\n \"Title: A correct characterization of strict positive realness for MIMO systems\\nYear: 2009\\n\\nAbstract: We present conditions which are necessary and sufficient for a transfer function (or transfer function matrix) to be strictly positive real. A counter example is given to illustrate that, in the MIMO (multi-input multi-output) case, the conditions presented here differ from those previously presented in the literature, and that these same conditions represent an incomplete characterization of strict positive realness (and passivity).\",\n \"Title: A characterization of the Hurwitz stability of Metzler matrices\\nYear: 2009\\n\\nAbstract: It is well known that a Hurwitz Metzler matrix is also diagonally stable. We obtain a necessary and sufficient condition for a matrix A to be diagonally stable from the Kalman-Yacubovich-Popov lemma. This condition is equivalent to requiring that a pair of LTI systems, of lower dimension, have a common Lyapunov function. This fact is made use of to derive very simple conditions for the Hurwitz stability of a Metzler matrix. These conditions are stated in terms of the signs of the diagonal entries of a sequence of lower dimensional matrices that are easily constructed.\",\n \"Title: A strategy for fair coexistence of loss and delay-based congestion control algorithms\\nYear: 2009\\n\\nAbstract: Delay-based TCP variants have attracted a large amount of attention in the networking community because of their ability to efficiently use network resources, control queuing delays, exhibit virtually zero packet loss, etc. One major issue that discourages the wider deployment of delay-based TCP variants is their inability to co-exist fairly with standard loss-based TCP. In this note we propose a simple mechanism that allows delay- and loss-based (AIMD) TCP flows to compete fairly with each other. Further, our approach ensures that delay-based flows automatically (and swiftly) switch to a low-delay regime if no loss-based flows are present. We provide analytical and simulation results to validate presented algorithm.\",\n \"Title: \\\"Fair-Share\\\" for Fair Bandwidth Allocation in Cloud Computing\\nYear: 2012\\n\\nAbstract: Current mechanisms for controlling network resources cannot prevent users from interfering with each other in a shared cloud environment. Proposals made to rectify this, use mechanisms which require interrupts with high timing precision, and usually unevenly distribute bandwidth to TCP flows. We propose the use of an alternative mechanism to manage network resources and compare the performance of both.\",\n \"Title: Generalized distributed rate limiting\\nYear: 2009\\n\\nAbstract: The distributed rate limiting (DRL) paradigm is a recently proposed mechanism for decentralized control of cloud-based services. DRL is a simple and efficient approach to resolve the issues of pricing and resource control/engineering of cloud based services. The existing DRL schemes focus on very specific performance metrics (such as loss rate and fair-share) and their design heavily depends on the assumption that the traffic is generated by elastic TCP sources. In this paper we tackle the DRL problem for general workloads and performance metrics and propose an analytic framework for the design of stable DRL algorithms. The closed-form nature of our results allows simple design rules which, together with extremely low communication overhead, makes the presented algorithms practical and easy to deploy with guaranteed convergence properties under a wide range of possible scenarios.\",\n \"Title: Cooperative Regulation and Trading of Emissions Using Plug-in Hybrid Vehicles\\nYear: 2013\\n\\nAbstract: We present a new approach to regulate traffic-related pollution in urban environments by utilizing hybrid vehicles. To do this, we orchestrate the way that each vehicle in a large fleet combines its two engines based on simple communication signals from a central infrastructure. Our approach can be viewed both as a control algorithm and as an optimization algorithm. The primary goal is to regulate emissions, and we discuss a number of control strategies to achieve this goal. Second, we want to allocate the available pollution budget in a fair way among the participating vehicles; again, we explore several different notions of fairness that can be achieved. The efficacy of our approach is exemplified both by the construction of a proof-of-concept vehicle and by extensive simulations, and is verified by mathematical analysis.\",\n \"Title: Stochastic Park-and-Charge Balancing for Fully Electric and Plug-in Hybrid Vehicles\\nYear: 2014\\n\\nAbstract: Motivated by the need to provide services to alleviate range anxiety of electric vehicles, we consider the problem of balancing charging demand across a network of charging stations. Our objective is to reduce the potential for excessively long queues to build up at some charging stations, although other charging stations are underutilized. A stochastic balancing algorithm is presented to achieve these goals. A further feature of this algorithm is that it is fully decentralized and facilitates a plug-and-play type of behavior. Using our system, the charging stations can join and leave the network without any changes to, or communication with, a centralized infrastructure. Analysis and simulations are presented to illustrate the efficacy of our algorithm.\",\n \"Title: Padé Discretization for Linear Systems With Polyhedral Lyapunov Functions\\nYear: 2011\\n\\nAbstract: This technical note has been motivated by the need to assess the preservation of polyhedral Lyapunov functions for stable continuous-time linear systems under numerical discretization of the transition matrix. This problem arises when discretizing linear systems in such a manner as to preserve a certain type of stability of the discrete time approximation. Our main contribution is to show that a continuous-time system and its Padé discretization (of any order and sampling) always share at least one common piecewise linear (polyhedral) Lyapunov function.\",\n \"Title: Adaptive williams filters with application to suspension control: The vector case\\nYear: 2009\\n\\nAbstract: With active vehicle suspension, one can tailor a vehicle's response to load and inertial disturbances without affecting the vehicle response to road disturbances. This decoupling is achieved by previous researchers and using a filtered combination of measured signals. These filters, which we call Williams filters, require exact knowledge of certain vehicle parameters including vehicle mass to achieve the desired decoupling. However, vehicle parameters, such as mass, are subject to abrupt variations as vehicle load changes. We propose an adaptive Williams filter that does not require knowledge of vehicle parameters and extends the results presented in.\",\n \"Title: Hurwitz Stability of Metzler Matrices\\nYear: 2010\\n\\nAbstract: In this note, a simple method is presented that is both necessary and sufficient for determining whether a given Metzler matrix A is Hurwitz. The method is based on the well known fact that a Hurwitz Metzler matrix is also diagonally stable. By using this fact, very simple conditions are derived for the Hurwitz stability of a Metzler matrix. The conditions are stated in terms of the signs of the diagonal entries of a sequence of lower dimensional matrices. The efficacy of the conditions is demonstrated by applying them to determine stability in several examples.\",\n \"Title: On the Characterization of Strict Positive Realness for General Matrix Transfer Functions\\nYear: 2010\\n\\nAbstract: We present conditions which are necessary and sufficient for a transfer function (or transfer function matrix) to be strictly positive real. A counter-example is given to illustrate that the conditions presented here differ from those previously presented in the literature. The proof of our results differs from previous related proofs in that it only uses properties of analytic functions and matrices and does not require state-space realizations. Also, the results are not restricted to rational transfer functions with real coefficients.\",\n \"Title: Distributed Dynamic Speed Scaling\\nYear: 2010\\n\\nAbstract: In recent years we have witnessed a great interest in large distributed computing platforms, also known as clouds. While these systems offer enormous computing power, they are major energy consumers. In existing data centers CPUs are responsible for approximately half of the energy consumed by the servers. A promising technique for saving CPU energy consumption is dynamic speed scaling, in which the speed at which the processor is run is adjusted based on demand and performance constraints. In this paper we look at the problem of allocating the demand in the network of processors (each being capable to perform dynamic speed scaling) to minimize the global energy consumption/cost subject to a performance constraint. The nonlinear dependence between the energy consumption and the performance as well as the high variability in the energy prices result in a nontrivial resource allocation. The problem can be abstracted as a fully distributed convex optimization with a linear constraint. On the theoretical side, we propose two low-overhead fully decentralized algorithms for solving the problem of interest and provide closed-form conditions that ensure stability of the algorithms. Then we evaluate the efficacy of the optimal solution using simulations driven by the real-world energy prices. Our findings indicate a possible cost reduction of 10-40% compared to power-oblivious 1/N load balancing, for a wide range of load factors.\",\n \"Title: Extensions of “Padé Discretization for Linear Systems With Polyhedral Lyapunov Functions” for Generalized Jordan Structures\\nYear: 2013\\n\\nAbstract: Recently, we showed that certain types of polyhedral Lyapunov functions for linear time-invariant systems, are preserved by diagonal Padé approximations, under the assumption that the continuous-time system matrix Ac has distinct eigenvalues. In this technical note, we show that this result also holds true in the case that Ac has non-trivial Jordan blocks.\",\n \"Title: Signaled Queueing\\nYear: 2015\\n\\nAbstract: Burstiness in queues where customers arrive independently leads to rush periods when wait times are long. We propose a simple signaling scheme to decrease wait times by distributing customer arrivals more uniformly. Agents receive one of several signals with suggestions on what time to join the queue. We quantify the efficiency gains, both analytically and empirically, with respect to a number of parameters of the proposed signaled queue, such as burstiness of arrivals, number of distinct signals, and propensity of customers to follow suggestions.\",\n \"Title: Data Assimilation for Linear Parabolic Equations: Minimax Projection Method\\nYear: 2015\\n\\nAbstract: In this paper we propose a state estimation method for linear parabolic partial differential equations (PDE) that accounts for errors in the model, truncation, and observations. It is based on an extension of the Galerkin projection method. The extended method models projection coefficients, representing the state of the PDE in some basis, by means of a differential-algebraic equation (DAE). The original estimation problem for the PDE is then recast as a state estimation problem for the constructed DAE using a linear continuous minimax filter. We construct a numerical time integrator that preserves the monotonic decay of a nonstationary Lyapunov function along the solution. To conclude, we demonstrate the efficacy of the proposed method by applying it to the tracking of a discharged pollutant slick in a two-dimensional fluid.\",\n \"Title: Smart Procurement of Naturally Generated Energy (SPONGE) for Plug-in Hybrid Electric Buses.\\nYear: 2017\\n\\nAbstract: We discuss a recently introduced ECO-driving concept known as smart procurement of naturally generated energy (SPONGE) in the context of plug-in hybrid electric buses. Examples are given to illustrate the benefits of this approach to ECO-driving. Finally, distributed algorithms to realize SPONGE are discussed, paying attention to the privacy implications of the underlying optimization problems.\",\n \"Title: An Ergodic Aimd Algorithm With Application To High-Speed Networks\\nYear: 2012\\n\\nAbstract: In this article we propose a version of the Additive-Increase Multiplicative-Decrease (AIMD) algorithm that provides a suitable basis to develop congestion control protocols that can be deployed in both conventional and high-speed communication networks. Our algorithm retains many of the properties of the standard AIMD algorithm. However, unlike other non-standard AIMD algorithms, our scheme can be shown to be ergodic under very general assumptions.\",\n \"Title: A Google-Like Model Of Road Network Dynamics And Its Application To Regulation And Control\\nYear: 2011\\n\\nAbstract: Inspired by the ability of Markov chains to model complex dynamics and handle large volumes of data in Google's PageRank algorithm, a similar approach is proposed here to model road network dynamics. The central component of the Markov chain is the transition matrix which can be completely constructed by easily collecting traffic data. The proposed model is validated using the popular mobility simulator SUMO. Markov chain theory and spectral analysis of the transition matrix are then shown to reveal non- evident properties of the underlying road network and to correctly predict consequences of road network modifications. Preliminary results from possible applications are shown and simple practical examples are provided throughout this article to clarify and support the theoretical expectations.\",\n \"Title: Some Results On Quadratic Stability Of Switched Systems With Interval Uncertainty\\nYear: 2007\\n\\nAbstract: Some results on quadratic stability of switched systems with interval uncertainty In this paper we present some results on the quadratic stability of switched systems with uncertain parameters. We show that the quadratic stability of a class of switched uncertain systems may be readily verified using simple algebraic conditions.\",\n \"Title: A Framework For Decentralised Feedback Connectivity Control With Application To Sensor Networks\\nYear: 2009\\n\\nAbstract: In this article, we propose a decentralised algorithm for connectivity maintenance in a distributed sensor network. Our algorithm uses the dynamics of a consensus algorithm to estimate the connectivity of a network topology in a decentralised manner. These estimates are then used to inform a decentralised control algorithm that regulates the network connectivity to some desired level. Under certain realistic assumptions we show that the closed-loop dynamics can be described as a consensus algorithm with an input, and eventually reduces to a scalar system. Bounds are given to ensure the stability of the algorithm and examples are given to illustrate the efficacy of the proposed algorithm.\",\n \"Title: Strict Positive Realness Of Descriptor Systems In State Space\\nYear: 2010\\n\\nAbstract: In this article, we give necessary and sufficient spectral conditions for various notions of strict positive realness for single-input single-output descriptor systems. These conditions only require calculation of eigenvalues of a single matrix. A characterisation of a Kalman-Yacubovich-Popov-like lemma for descriptor systems is also derived, and its implications for the stability of a class of switched descriptor systems are briefly discussed.\",\n \"Title: Traffic Modelling Framework For Electric Vehicles\\nYear: 2012\\n\\nAbstract: This article reviews and improves a recently proposed model of road network dynamics. The model is also adapted and generalised to represent the patterns of battery consumption of electric vehicles travelling in the road network. Simulations from the mobility simulator SUMO are given to support and to illustrate the efficacy of the proposed approach. Applications relevant in the field of electric vehicles, such as optimal routing and traffic load control, are provided to illustrate how the proposed model can be used to address typical problems arising in contemporary road network planning and electric vehicle mobility.\",\n \"Title: A Flexible Distributed Framework For Realising Electric And Plug-In Hybrid Vehicle Charging Policies\\nYear: 2012\\n\\nAbstract: Motivated by the problems of charging a number of electric vehicles via limited capacity infrastructure, this article considers the problem of individual load adjustment under a total capacity constraint. For reasons of scalability and simplified communications, distributed solutions to this problem are sought. Borrowing from communication networks (AIMD algorithms) and distributed convex optimisation, we describe a number of distributed algorithms for achieving relative average fairness whilst maximising utilisation. We present analysis and simulation results to show the performance of these algorithms. In the scenarios examined, the algorithm's performance is typically within 5% of that achievable in the ideal centralised case, but with greatly enhanced scalability and reduced communication requirements.\",\n \"Title: Results In Cooperative Control And Implicit Consensus\\nYear: 2011\\n\\nAbstract: This article is concerned with a class of decentralised control problems that arise in contemporary applications, where agents cooperate to control and regulate a global quantity, are limited in the manner in which they communicate with each other, and are required to reach consensus on some implicit variable (e. g. CO2 emissions). Three algorithms are presented for achieving this goal. The convergence of these algorithms are proven, and their efficacy is demonstrated in simulations.\",\n \"Title: Exact stability test and stabilization for fractional systems\\nYear: 2015\\n\\nAbstract: In this paper we point out a connection between regular chains and the stability of fractional order systems. This observation leads to an elementary test for the stability of commensurate fractional systems.\",\n \"Title: On The Design And Synthesis Of Limit Cycles Using Switching Linear Systems\\nYear: 2010\\n\\nAbstract: This article deals with the design and synthesis of limit cycles for a class of switched linear systems. This work is motivated by an application in the context of electrical networks, but the methodologies can be applied in other engineering fields as well. Several methods for the design and synthesis of limit cycles are presented. Based on a monodromy matrix associated with a periodically switched system, a design method and two feedback strategies are developed. The first strategy is based on linear feedback design using pole placement. The second strategy is based on the observation that certain state-dependent switching strategies can be implemented by means of a simple nonlinear output feedback controller. Advantages of this latter strategy are not only the ease with which the switching strategy can be implemented, but also the fact that classical techniques may also be used to ascertain the stability of the resulting limit cycle. Our next contribution is the development of a novel frequency domain-based approach to limit cycle design. This approach is based on the observation that the existence of certain limit cycles can be deduced from an infinity of circle criteria generated by a family of periodic systems. By making use of recent results, this observation can be used to develop a one-parameter spectral search to deduce the approximate frequencies of feasible limit cycles. Having selected a frequency of oscillation, one may then make use of the aforementioned nonlinear elements to realise a switching strategy that generates a stable limit cycle with given frequency and amplitude. Examples are given to illustrate the effectiveness of the approaches presented.\",\n \"Title: On Maximum Sector Bounds For Absolute Stability Of Single-Input Single-Output Systems\\nYear: 2007\\n\\nAbstract: We consider the classical problem of absolute stability, i.e. stability of a linear time-invariant system in feedback with a memoryless time-varying sector bound non-linearity. We derive necessary and sufficient conditions for the existence of periodic motion. For the special case of symmetric sector bounds, this condition yields the minimum sector bounds for which the system can sustain periodic motion. By guaranteeing the absence of periodic motion we derive non-conservative sufficient conditions for absolute stability for arbitrary sector bounds. We demonstrate by numerical examples the application of our results.\",\n \"Title: Comments And Observations On The Passivity Of Descriptor Systems In State Space\\nYear: 2013\\n\\nAbstract: In this article, we give necessary and sufficient conditions for passivity of descriptor systems. These conditions are easily verifiable and apply without restriction to all descriptor systems.\",\n \"Title: A Methodology For The Design Of Robust Rollover Prevention Controllers For Automotive Vehicles With Active Steering\\nYear: 2007\\n\\nAbstract: In this paper we present a robust controller design methodology for vehicle rollover prevention utilizing active steering. Control design is based on keeping the magnitude of the vehicle load transfer ratio (LTR) below a certain level in the presence of driver steering inputs; we also develop an exact expression for LTR. The proposed controllers have a proportional-integral structure whose gain matrices are obtained using the results of Pancake et al. (2000) (T. Pancake, M. Corless and M. Brockman, \\\"Analysis and control of polytopic uncertain/nonlinear systems in the presence of bounded disturbance inputs'', Proceedings of the American Control Conference, Chicago, IL, June 2000; T. Pancake, M. Corless and M. Brockman, \\\"Analysis and control for a class of uncertain/nonlinear systems in the presence of bounded disturbance inputs'', 2007). These controllers reduce the transient magnitude of the LTR while maintaining the steady state steering response of the vehicle. The controllers can be designed to be robust with respect to vehicle parameters such as speed and centre of gravity height. We also provide a modi. cation to the controllers so that they only activate when the potential for rollover is significant. Numerical simulations demonstrate the efficacy of our approach and the resulting controllers.\",\n \"Title: Optimal Real-Time Distributed V2g And G2v Management Of Electric Vehicles\\nYear: 2014\\n\\nAbstract: This paper exploits the analogy between the electrical grid and modern communication networks to implement Electric Vehicle (EV) battery charging scheduling algorithms inspired by popular communication network techniques. In preliminary works, a similar approach was used to manage the Grid-to-Vehicle (G2V) active power flows. In this paper, we extend this framework to both implement the Vehicle-to-Grid (V2G) concept and to provide reactive power compensation capabilities that do not affect charging times. The ability of the proposed algorithms to optimally share the available/desired power in a fair way, with minimum communication requirements, in a very uncertain, dynamically changing framework, is illustrated through several examples for different scenarios of interest.\",\n \"Title: Signalling And Obfuscation For Congestion Control\\nYear: 2015\\n\\nAbstract: We aim to reduce the social cost of congestion in many smart city applications. In our model of congestion, agents interact over limited resources after receiving signals from a central agent that observes the state of congestion in real time. Under natural models of agent populations, we develop new signalling schemes and show that by introducing a non-trivial amount of uncertainty in the signals, we reduce the social cost of congestion, i.e., improve social welfare. The signalling schemes are efficient in terms of both communication and computation, and are consistent with past observations of the congestion. Moreover, the resulting population dynamics converge under reasonable assumptions.\",\n \"Title: A Big-Data Model For Multi-Modal Public Transportation With Application To Macroscopic Control And Optimisation\\nYear: 2015\\n\\nAbstract: This paper describes a Markov-chain-based approach to modelling multi-modal transportation networks. An advantage of the model is the ability to accommodate complex dynamics and handle huge amounts of data. The transition matrix of the Markov chain is built and the model is validated using the data extracted from a traffic simulator. A realistic test-case using multi-modal data from the city of London is given to further support the ability of the proposed methodology to handle big quantities of data. Then, we use the Markov chain as a control tool to improve the overall efficiency of a transportation network, and some practical examples are described to illustrate the potentials of the approach.\",\n \"Title: Alleviating A Form Of Electric Vehicle Range Anxiety Through On-Demand Vehicle Access\\nYear: 2015\\n\\nAbstract: On-demand vehicle access is a method that can be used to reduce types of range anxiety problems related to planned travel for electric vehicle owners. Using ideas from elementary queueing theory, basic quality of service (QoS) metrics are defined to dimension a shared fleet to ensure high levels of vehicle access. Using mobility data from Ireland, it is argued that the potential cost of such a system is very low.\",\n \"Title: On Closed-Loop Bicycle Availability Prediction\\nYear: 2015\\n\\nAbstract: We study the effect of customer choices in bicycle-sharing systems based on bicycle availability predictions. We show that such systems may lead to flapping behavior between bicycle stations. The consequences of flapping instability include poor user experience and suboptimal usage of the available bicycle stock. We propose a simple assignment strategy aimed at eliminating flapping and balancing d...\",\n \"Title: Person-Specific Standardized Vulnerability Assessment in Health and Social Care.\\nYear: 2015\\n\\nAbstract: We describe an integrated person-specific standardized vulnerability assessment model designed to facilitate patient management in health and social care. Such a system is not meant to replace existing health and social assessment models but rather to complement them by providing a holistic picture of the vulnerabilities faced by a given patient. In fact, it should be seen as a screening tool for health and social care workers. One key aspect of the modeling framework is the ability to provide personalized yet standardized multi-dimensional assessments of risk based on incomplete information about the patient status, as is the case in screening situations. Specifically, we integrate a Markov chain model describing the evolution of patients in and out of vulnerable states over time with a Bayesian network that serves to customize the dynamic model. We present an application in the context of elder care.\",\n \"Title: Smart Procurement Of Naturally Generated Energy (Sponge) For Phevs\\nYear: 2016\\n\\nAbstract: In this paper, we propose a new engine management system for hybrid vehicles to enable energy providers and car manufacturers to provide new services. Energy forecasts are used to collaboratively orchestrate the behaviour of engine management systems of a fleet of plug-in hybrid electric vehicle (PHEVs) to absorb oncoming energy in a smart manner. Cooperative algorithms are suggested to manage the energy absorption in an optimal manner for a fleet of vehicles, and the mobility simulator SUMO (Simulation of Urban MObility) is used to demonstrate the efficacy of the proposed idea.\",\n \"Title: On Source-Term Parameter Estimation for Linear Advection-Diffusion Equations with Uncertain Coefficients.\\nYear: 2016\\n\\nAbstract: In this paper, we propose an algorithm for estimating parameters of a source term of a linear advection-diffusion equation with an uncertain advection-velocity field. First, we apply a minimax state estimation technique in order to reduce uncertainty introduced by the coefficients. Then we design a source localization algorithm which uses the state estimator as a model and estimates the parameters of the source term given incomplete and noisy data. The principal novelty of the proposed algorithm is in that it is robust with respect to uncertainty in advection coefficients. The localization algorithm is sequential; that is, it updates both the state estimate and the source estimate once a new observation arrives. To demonstrate the efficacy of the proposed algorithm, we present a numerical example of source localization in two spatial dimensions for the advection-dominated transport of a nonreactive pollutant emanating from a point source.\",\n \"Title: An intelligent speed advisory system for electric vehicles\\nYear: 2015\\n\\nAbstract: Intelligent Transportation Systems (ITS) can be used to involve vehicles and the road infrastructure to cooperatively implement a number of innovative and useful applications. Here, we explore the possibility to adopt a consensus based distributed speed advisory system to determine the optimal recommended speed in urban areas where only electric vehicles are allowed to travel (e.g., in the city centre). The optimality criterion is to maximise the energy efficiency of a fleet of vehicles travelling in the restricted area, and we adopt recently proposed distributed privacy-preserving consensus algorithms to achieve the desired objective.\",\n \"Title: A Markov-chain based model for a bike-sharing system\\nYear: 2015\\n\\nAbstract: Bike-sharing systems are recently becoming ubiquitous in most cities, as an environmentally friendly alternative to other means of transportation. An optimal management of the bike-sharing service would in principle benefit from the availability of a mathematical model underlying the system. Accordingly, in this paper we propose a Markov-chain based approach to model the bike-sharing system, which we believe has a potential to develop alternative methods to implement classic control actions in a bike-sharing system (e.g., in terms of implementing alternative relocation strategies or planning advertising campaigns). The proposed methodology is validated on real data from the bike-sharing system in Boston, USA, and a first application of the proposed model is preliminarily illustrated in the paper.\",\n \"Title: Localization of missing entities using parked cars\\nYear: 2015\\n\\nAbstract: We introduce a novel application to detect tagged entities using a platform based on parked cars. We show experimental results based on real data from the city of Dublin.\",\n \"Title: Cooperative control and smart procurement of naturally generated energy (SPONGE) for PHEVs\\nYear: 2015\\n\\nAbstract: Electric vehicles can potentially be the best means of transportation for improving air quality, provided that they are powered by electricity from natural gas or wind, water or solar power. In this paper we describe a simple cooperative algorithm that exploits the energy management units of Plug-in Hybrid Electric Vehicles (PHEVs) to absorb the expected forthcoming energy available from renewable sources. The proposed approach bridges the gap between mobility patterns and power grid constraints, and allows to prevent green energy from being wasted while at the same time reducing the complexity burden of the power grid to charge unexpected loads of electric vehicles. Simulation results are given to show the efficacy of the proposed method.\",\n \"Title: Pedestrian-Aware Engine Management Strategies for Plug-in Hybrid Electric Vehicles.\\nYear: 2018\\n\\nAbstract: Electric vehicles (EVs) and plug-in hybrid EVs (PHEVs) are increasingly being seen as a means of mitigating the pressing concerns of traffic-related pollution. While hybrid vehicles are usually designed with the objective of minimizing fuel consumption, in this paper we propose a engine management strategies that also consider environmental effects of the vehicles to pedestrians outside of the veh...\",\n \"Title: On The Design Of A Route Parsing Engine For Connected Vehicles With Applications To Congestion Management Systems\\nYear: 2016\\n\\nAbstract: In this paper we present a new type of congestion management system to regulate congestion around a single link obstruction. This obstruction will be investigated in two cases: a) a regular obstruction and b) an irregular obstruction. The principle innovations of our system are to utilise a route parsing engine to both predict the likelihood of a vehicle being affected by the obstruction and make decisions ahead of time, and to use this information to make a fair congestion management system.\",\n \"Title: Consensus With State Obfuscation: An Application To Speed Advisory Systems\\nYear: 2016\\n\\nAbstract: In this paper, we present a new speed advisory system (SAS). The system provides indications to drivers which, if followed, guide the network of vehicles towards a common speed. The SAS we present is distributed and one of its key features is that the vehicles are guided towards the common speed by receiving obfuscated information. Essentially, this means that the desired network behaviour is achieved and, at the same time, there is no vehicle in the network that obtains clear knowledge of the state of any other vehicle. This results in a privacy-preserving feature which is particularly useful in smart cities applications, where drivers might not be willing to share their transient state with others.\",\n \"Title: Hybrid Urban Navigation For Smart Cities\\nYear: 2017\\n\\nAbstract: This paper proposes a design for a hybrid, citywide urban navigation system for moving agents demanding dedicated navigation support. The system combines GPS and vehicle-to-vehicle communication from an ad-hoc network of parked cars, and RFID from fixed infrastructure-such as smart traffic lights-to enable a safely navigable city. Applications for such a system include high speed drone navigation and directing visually impaired pedestrians.\",\n \"Title: Cyberphysics, pollution mitigation, and pedelecs.\\nYear: 2017\\n\\nAbstract: The effect of transport-related pollution on human health is fast becoming recognised as a major issue in cities worldwide. Cyclists, in particular, face great risks, as they typically are most exposed to tail-pipe emissions. Three avenues are being explored worldwide in the fight against urban pollution: (i) outright bans on polluting vehicles and embracing zero tailpipe emission vehicles; (ii) measuring air-quality as a means to better informing citizens of zones of higher pollution; and (iii) developing smart mobility devices that seek to minimize the effect of polluting devices on citizens as they transport goods and individuals in our cities. Following this latter direction, in this paper we present a new way to protect cyclists from the effect of urban pollution. Namely, by exploiting the actuation possibilities afforded by pedelecs or e-bikes (electric bikes), we design a cyber-physical system that mitigates the effect of urban pollution by indirectly controlling the breathing rate of cyclists in polluted areas. Results from a real device are presented to illustrate the efficacy of our system.\",\n \"Title: On the stability and convergence of a class of consensus systems with a nonlinear input.\\nYear: 2017\\n\\nAbstract: We consider a class of consensus systems driven by a nonlinear input. Such systems arise in a class of Internet of Things (IOT) applications. Our objective in this paper is to determine conditions under which a certain partially distributed system converges to a Lur’e-like scalar system, and to provide a rigorous proof of its stability. Conditions are derived for the non-uniform convergence and stability of such a system and an example is given of a speed advisory system where such a system arises.\",\n \"Title: Distributed Multi-resource Allocation with Little Communication Overhead.\\nYear: 2017\\n\\nAbstract: We propose a distributed algorithm to solve a special distributed multi-resource allocation problem with no direct inter-agent communication. We do so by extending a recently introduced additive-increase multiplicative-decrease (AIMD) algorithm, which only uses very little communication between the system and agents. Namely, a control unit broadcasts a one-bit signal to agents whenever one of the allocated resources exceeds capacity. Agents then respond to this signal in a probabilistic manner. In the proposed algorithm, each agent is unaware of the resource allocation of other agents. We also propose a version of the AIMD algorithm for multiple binary resources (e.g., parking spaces). Binary resources are indivisible unit-demand resources, and each agent either allocated one unit of the resource or none. In empirical results, we observe that in both cases, the average allocations converge over time to optimal allocations.\",\n \"Title: On the AIMD Algorithm Under Saturation Constraints.\\nYear: 2017\\n\\nAbstract: One of the most successful distributed resource allocation algorithms to be deployed in industry is the Additive-Increase Multiplicative-Decrease (AIMD) algorithm of Jain and Chiu. This algorithm already underpins the transport layer of the internet, and is now starting to find application in new areas in the context of Smart Grid and Smart Transportation applications. A distinguishing feature of these latter application areas, when compared with the internet, is the need to modify AIMD to account for lower and upper bounds in the resource allocated to individual agents. Our objective in this note is to demonstrate that the dynamic system arising from AIMD in this extended form has system theoretic properties similar to the classical algorithm.\",\n \"Title: On Charge Point Anxiety And The Sharing Economy\\nYear: 2017\\n\\nAbstract: This paper addresses some of the issues surrounding the charging of electric vehicles (EVs) with a particular focus on charge points. We discuss the design and implementation of a charge point adapter. The key feature of the adapter is that it provides privately owned charge points with the opportunity to be rented to members of the public, resulting in additional charging opportunities for EVs. We present a number of use cases whereby the adapter is used to alleviate the demand for EV charging in an area that experiences a shortage of charge points, but where private, unused charge points are available.\",\n \"Title: Leader and Leaderless Multi-Layer Consensus With State Obfuscation: An Application to Distributed Speed Advisory Systems.\\nYear: 2018\\n\\nAbstract: Two new distributed speed advisory systems (SASs) are introduced in this paper. The systems implement consensus algorithms that guide a set of vehicles toward a common driving speed. A major innovation is that consensus is achieved over a multi-layer network, in which parallel network topologies of connected vehicles are superimposed. The reason for the use of these parallel networks is that, in t...\",\n \"Title: On the control of agents coupled through shared resources.\\nYear: 2018\\n\\nAbstract: We consider a control problem involving a number of agents coupled through multiple unit-demand resources. Such resources are indivisible and each agentu0027s consumption is modeled as a Bernoulli random variable. Controlling such agents in a probabilistic manner, subject to capacity constraints, is ubiquitous in smart cities. For instance, such agents can be humans are in a feedback loop---who respond to a price signal), or automated decision-support systems that strive toward system-level goals. In this paper, we consider both a single feedback loop corresponding to a single resource and multiple coupled feedback loops corresponding to multiple resources consumed by the same population of agents. For example, when a network of devices allocate resources to deliver a number of services, these services are coupled through capacity constraints on these resources. We present a new algorithm with basic guarantees of convergence and optimality, as well as an example illustrating its performance.\",\n \"Title: A Non-Invasive Method for the Safe Interaction of Cities and Electric Vehicle Fleets.\\nYear: 2018\\n\\nAbstract: Electric and hybrid vehicles are growing in popularity. While these vehicles produce less pollution, they also produce less audible noise, especially at lower speeds. This makes it harder for pedestrians and cyclists to detect an approaching vehicle. Thus, an additional system is required to detect electric and hybrid vehicles and alert pedestrians and cyclists of their whereabouts, especially while these vehicles are driving at low speeds in cities. This paper introduces one such method based on high frequency audio emissions that are present in EVs, which arise, for example, from the process of magnetostriction. Our method is tested experimentally using four different tests vehicles, and a preliminary EV detection algorithm is also presented.\",\n \"Title: Distributed Ledger Technology, Cyber-Physical Systems, and Social Compliance.\\nYear: 2018\\n\\nAbstract: This paper describes how distributed ledger technologies (DLTs) can be used to enforce social contracts and to orchestrate the behavior of agents trying to access a shared resource. The first part of this paper analyzes the advantages and disadvantages of using DLTs architectures to implement certain control systems in an Internet of Things (IoT) setting and then focuses on a specific type of DLT based on a directed acyclic graph. In this setting, we propose a set of delay differential equations to describe the dynamical behavior of the Tangle, an IoT-inspired directed acyclic graph designed for the cryptocurrency IOTA. The second part proposes an application of DLTs as a mechanism for dynamic deposit pricing, wherein the deposit of digital currency is used to orchestrate access to a network of shared resources. The pricing signal is used as a mechanism to enforce the desired level of compliance according to a predetermined set of rules. After presenting an illustrative example, we analyze the control system and provide sufficient conditions for the stability of the network.\",\n \"Title: Communication-efficient Distributed Multi-resource Allocation.\\nYear: 2018\\n\\nAbstract: In several smart city applications, multiple resources must be allocated among competing agents that are coupled through such shared resources and are constrained — either through limitations of communication infrastructure or privacy considerations. We propose a distributed algorithm to solve such distributed multi-resource allocation problems with no direct inter-agent communication. We do so by extending a recently introduced additive-increase multiplicative-decrease (AIMD) algorithm, which only uses very little communication between the system and agents. Namely, a control unit broadcasts a one-bit signal to agents whenever one of the allocated resources exceeds capacity. Agents then respond to this signal in a probabilistic manner. In the proposed algorithm, each agent makes decision of its resource demand locally and an agent is unaware of the resource allocation of other agents. In empirical results, we observe that the average allocations converge over time to optimal allocations.\",\n \"Title: Context-Based Cyclist Intelligent Support: An Approach To E-Bike Control Based On Smartphone Sensors\\nYear: 2018\\n\\nAbstract: Electrically assisted bicycles (e-bikes or pedelecs) have recently become popular as a means of personal transportation, particularly in cities. Pedelecs allow people to combine their muscular strength in varying proportions with the assistance of an electric engine. One of the challenges here is to determine the cyclist preferences, capabilities, and the context situation around the e-bike and, based on these, to make recommendations to the cyclist and also to control the degree of electrical assistance provided. The Smart Space concept is used here for context formation. The concept involves creation of a real-time model of the physical space that aids decision making about electrical engine utilization for the particular situation and generates a recommendation for the cyclist. An ontology-based publish/subscribe mechanism is used for information sharing in Smart Space.\",\n \"Title: ISS Property with Respect to Boundary Disturbances for a Class of Riesz-Spectral Boundary Control Systems.\\nYear: 2018\\n\\nAbstract: This paper deals with the establishment of Input-to-State Stability (ISS) estimates for infinite dimensional systems with respect to both boundary and distributed disturbances. First, a new approach is developed for the establishment of ISS estimates for a class of Riesz-spectral boundary control systems satisfying certain eigenvalue constraints. Second, a concept of weak solutions is introduced in order to relax the disturbances regularity assumptions required to ensure the existence of classical solutions. The proposed concept of weak solutions, that applies to a large class of boundary control systems which is not limited to the Riesz-spectral ones, provides a natural extension of the concept of both classical and mild solutions. Assuming that an ISS estimate holds true for classical solutions, we show the existence, the uniqueness, and the ISS property of the weak solutions.\",\n \"Title: Distributed Ledger Technology for Smart Cities, the Sharing Economy, and Social Compliance.\\nYear: 2018\\n\\nAbstract: This paper describes how distributed ledger technologies (DLTs) can be used to enforce social contracts and to orchestrate the behavior of agents trying to access a shared resource. The first part of this paper analyzes the advantages and disadvantages of using DLTs architectures to implement certain control systems in an Internet of Things (IoT) setting and then focuses on a specific type of DLT based on a directed acyclic graph. In this setting, we propose a set of delay differential equations to describe the dynamical behavior of the Tangle, an IoT-inspired directed acyclic graph designed for the cryptocurrency IOTA. The second part proposes an application of DLTs as a mechanism for dynamic deposit pricing , wherein the deposit of digital currency is used to orchestrate access to a network of shared resources. The pricing signal is used as a mechanism to enforce the desired level of compliance according to a predetermined set of rules. After presenting an illustrative example, we analyze the control system and provide sufficient conditions for the stability of the network.\",\n \"Title: A New Take on Protecting Cyclists in Smart Cities.\\nYear: 2018\\n\\nAbstract: Pollution in urban centers is becoming a major societal problem. While pollution is a concern for all urban dwellers, cyclists are one of the most exposed groups due to their proximity to vehicle tailpipes. Consequently, new solutions are required to help protect citizens, especially cyclists, from the harmful effects of exhaust-gas emissions. In this context, hybrid vehicles (HVs) offer new actua...\",\n \"Title: Identification Of New Patterns In Urban Traffic Flows\\nYear: 2018\\n\\nAbstract: Traffic flow pattern identification, as well as anomaly detection, is known to be an important component for traffic operations and control. Alongside classical applications, mainly, to improve the safety and the comfort of drivers, more recently there is a growing interest in gathering personalised route information to provide customised services. With this latter application in mind, in this paper we investigate the ability of simple macroscopic information (i.e., time varying junction turning probabilities) to identify changes in nominal urban traffic flows, most likely due to the occurrence of external events (e.g., road works or traffic congestions). Some preliminary results obtained with the use of a realistic mobility simulator are also illustrated and discussed, and some candidate applications are briefly outlined.\",\n \"Title: Distributed Algorithms for Internet-of-Things enabled Prosumer Markets: A Control Theoretic Perspective.\\nYear: 2018\\n\\nAbstract: Internet-of-Things (IoT) enables the development of sharing economy applications. In many sharing economy scenarios, agents both produce as well as consume a resource; we call them prosumers. A community of prosumers agrees to sell excess resource to another community in a prosumer market. In this chapter, we propose a control theoretic approach to regulate the number of prosumers in a prosumer community, where each prosumer has a cost function that is coupled through its time-averaged production and consumption of the resource. Furthermore, each prosumer runs its distributed algorithm and takes only binary decisions in a probabilistic way, whether to produce one unit of the resource or not and to consume one unit of the resource or not. In the proposed approach, prosumers do not explicitly exchange information with each other due to privacy reasons, but little exchange of information is required for feedback signals, broadcast by a central agency. In the proposed approach, prosumers achieve the optimal values asymptotically. Furthermore, the proposed approach is suitable to implement in an IoT context with minimal demands on infrastructure. We describe two use cases; community-based car sharing and collaborative energy storage for prosumer markets. We also present simulation results to check the efficacy of the algorithms.\",\n \"Title: On Synchronization in Continuous-Time Networks of Nonlinear Nodes With State-Dependent and Degenerate Noise Diffusion.\\nYear: 2019\\n\\nAbstract: In this paper, we present a generalization of a recent result on the almost sure consensus for networks affected by relative-state-dependent measurement noise. Specifically, we give two sufficient conditions for the synchronization of networks of diffusively coupled nonlinear nodes affected by certain state-dependent noise diffusion processes. We use this condition to study the onset of synchroniz...\",\n \"Title: IOTA-based Directed Acyclic Graphs without Orphans.\\nYear: 2019\\n\\nAbstract: Directed Acylic Graphs (DAGs) are emerging as an attractive alternative to traditional blockchain architectures for distributed ledger technology (DLT). In particular DAG ledgers with stochastic attachment mechanisms potentially offer many advantages over blockchain, including scalability and faster transaction speeds. However, the random nature of the attachment mechanism coupled with the requirement of protection against double-spend transactions leaves open the possibility that not all transactions will be eventually validated. Such transactions are said to be orphaned, and will never be validated. Our principal contribution is to propose a simple modification to the attachment mechanism for the Tangle (the IOTA DAG architecture). This modification ensures that all transactions are validated in finite time, and preserves essential features of the popular Monte-Carlo selection algorithm. In order to demonstrate these results we derive a fluid approximation for the Tangle (in the limit of infinite arrival rate) and prove that this fluid model exhibits the desired behavior. We also present simulations which validate the results for finite arrival rates.\",\n \"Title: Derandomized Distributed Multi-resource Allocation with Little Communication Overhead.\\nYear: 2018\\n\\nAbstract: We study a class of distributed optimization problems for multiple shared resource allocation in Internet-connected devices. We propose a derandomized version of an existing stochastic additive-increase and multiplicative-decrease (AIMD) algorithm. The proposed solution uses one bit feedback signal for each resource between the system and the Internet-connected devices and does not require inter-device communication. Additionally, the Internet-connected devices do not compromise their privacy and the solution does not dependent on the number of participating devices. In the system, each Internet-connected device has private cost functions which are strictly convex, twice continuously differentiable and increasing. We show empirically that the long-term average allocations of multiple shared resources converge to optimal allocations and the system achieves minimum social cost. Furthermore, we show that the proposed derandomized AIMD algorithm converges faster than the stochastic AIMD algorithm and both the approaches provide approximately same solutions.\",\n \"Title: A Context-Aware E-Bike System to Reduce Pollution Inhalation While Cycling.\\nYear: 2019\\n\\nAbstract: The effect of transport-related pollution on human health is fast becoming recognized as a major issue in cities worldwide. Cyclists, in particular, face great health risks, as they typically are most exposed to tail-pipe emissions. Four avenues are being explored to combat urban air pollution: 1) policy interventions such as outright bans on polluting vehicles, 2) embracing zero tailpipe emission...\",\n \"Title: An Adaptive AIMD Congestion Control Protocol for Communication Networks\\nYear: 2004\\n\\nAbstract: We present a new adaptive TCP protocol for the control of congestion in communication networks. The key innovative idea in our protocol is to combine results from Frobenius-Perron theory with online adaptation to realise a TCP variant that: (i) allocates the network pipe fairly amongst competing flows; (ii) coexists with other TCP variants; (iii) responds rapidly to changes in available bandwidth; and (iv) which strives to achieve a high data rate through the bottleneck link. When implemented, the new protocol requires only sender-side modification of the standard window congestion control scheme and is transparent to network buffers and network sources operating other TCP-variants. Results from the network simulator NS are presented to illustrate the key features of our scheme.\",\n \"Title: R-Extreme Signalling For Congestion Control\\nYear: 2016\\n\\nAbstract: In many smart city' applications, congestion arises in part due to the nature of signals received by individuals from a central authority. In the model of Mareek et al., each agent uses one out of multiple resources at each time instant. The per-use cost of a resource depends on the number of concurrent users. A central authority has up-to-date knowledge of the congestion across all resources and uses randomisation to provide a scalar or an interval for each resource at each time. In this paper, the interval to broadcast per resource is obtained by taking the minima and maxima of costs observed within a time window of length r, rather than by randomisation. We show that the resulting distribution of agents across resources also converges in distribution, under plausible assumptions about the evolution of the population over time.\",\n \"Title: On the SPRification of Linear Descriptor Systems via Output Feedback\\nYear: 2019\\n\\nAbstract: We consider input–output systems in descriptor form and ask when such systems can be rendered strictly positive real (SPR) via output feedback. Time- and frequency-domain conditions are given to determine when and how this is possible. In addition, a synthesis procedure for controller design is also derived. Together, the results provide a complete answer to when a linear descriptor system can be made SPR via output feedback, and provide a recipe for design of a feedback controller when one exists.\",\n \"Title: A Hidden Markov Model For Route And Destination Prediction\\nYear: 2018\\n\\nAbstract: We present a simple model and algorithm for predicting driver destinations and routes, based on the input of the latest road links visited as part of an ongoing trip. The algorithm may be used to predict any clusters previously observed in a driver's trip history. It assumes that the driver's historical trips are grouped into clusters sharing similar patterns. Given a new trip, the algorithm attempts to predict the cluster in which the trip belongs. The proposed algorithm has low temporal complexity. In addition, it does not require the transition and emission matrices of the Markov chain to be computed. Rather it relies on the frequencies of co-occurrences of road links and trip clusters. We validate the proposed algorithm against an experimental dataset. We discuss the success and convergence of the algorithm and show that our algorithm has a high prediction success rate.\",\n \"Title: Recovering Markov Models from Closed-Loop Data.\\nYear: 2019\\n\\nAbstract: Abstract Situations in which recommender systems are used to augment decision making are becoming prevalent in many application domains. Almost always, these prediction tools (recommenders) are created with a view to affecting behavioural change. Clearly, successful applications actuating behavioural change, affect the original model underpinning the predictor, leading to an inconsistency. This feedback loop is often not considered in standard machine learning techniques which rely upon machine learning/statistical learning machinery. The objective of this paper is to develop tools that recover unbiased user models in the presence of recommenders. More specifically, we assume that we observe a time series which is a trajectory of a Markov chain R modulated by another Markov chain S , i.e. the transition matrix of R is unknown and depends on the current state of S . The transition matrix of the latter is also unknown. In other words, at each time instant, S selects a transition matrix for R within a given set which consists of known and unknown matrices. The state of S , in turn, depends on the current state of R thus introducing a feedback loop. We propose an Expectation–Maximisation (EM) type algorithm, which estimates the transition matrices of S and R . Experimental results are given to demonstrate the efficacy of the approach.\",\n \"Title: On the design of a decision engine for connected vehicles with an application to congestion management.\\nYear: 2018\\n\\nAbstract: Vehicles are becoming connected entities. As a result, a likely scenario is that such entities might be literally bombarded with information from a multitude of devices. In this context, a key challenging requirement for both connected and autonomous vehicles is that they will need to become cognitive bodies, able to parse information and use only the pieces of information that are relevant to the vehicle in the context of a given journey. In order to address this fundamental requirement, a decision engine is presented in this paper. The engine makes it possible for the vehicle to understand which pieces of information are really relevant, and subsequently to process only those pieces of information. In order to illustrate the key features of our system, we show that it is possible to build upon the engine to develop a distributed traffic management system, and then we validate such a system via both conventional (numerical and SUMO-based) simulations and a Hardware-in-the-Loop (HIL) platform. Both the conventional simulations and the HIL validation showed that the engine can be effectively used to design a distributed traffic management system.\",\n \"Title: A Distributed Markovian Parking Assist System\\nYear: 2019\\n\\nAbstract: This paper proposes a congestion balancing parking guidance system that suggests to a driver a sequence of streets to follow around the desired destination with the aim to reduce the total distance that is travelled while searching for a free parking spot. The system requires only limited infrastructure information, and neither requires parking spaces to be instrumented, nor vehicles to communicate with each other. Specifically, the system utilizes parking vacancy information on each street. The system also accounts for the added cost of not finding a free space, which is typically expressed as the additional distance that needs to be travelled to find an available parking spot. To avoid local congestion, different drivers respond to different suggestions based on a probability distribution that considers the total distance that needs to be travelled. A mobility simulator is used to model the searching behaviors of vehicles for parking spaces with and without the smart parking algorithm and experimental results are provided using the road network of the city of Dublin, Ireland.\",\n \"Title: Distributed Ledger Technology for IoT: Parasite Chain Attacks.\\nYear: 2019\\n\\nAbstract: Directed Acyclic Graph (DAG) based Distributed Ledgers can be useful in a number of applications in the IoT domain. A distributed ledger should serve as an immutable and irreversible record of transactions, however, a DAG structure is a more complicated mathematical object than its blockchain counterparts, and as a result, providing guarantees of immutability and irreversibility is more involved. In this paper, we analyse a commonly discussed attack scenario known as a parasite chain attack for the IOTA Foundation DAG based ledger. We analyse the efficacy of IOTA core MCMC algorithm using a matrix model and present an extension which improves the ledger resistance to these attacks.\",\n \"Title: A LMI condition for the Robustness of Linear Predictor Feedback with Respect to Time-Varying Input Delays.\\nYear: 2019\\n\\nAbstract: This paper discusses the robustness of the predictor feedback in the case of an unknown time varying delay. Specifically, we study the stability of the closed-loop system when the predictor feedback is designed based on the knowledge of the nominal value of the time-varying delay. By resorting to an adequate Lyapunov-Krasovskii functional, we derive a LMI-based sufficient condition ensuring the asymptotic stability of the closed-loop system for small enough variations of the time-varying delay around its nominal value. These results are extended to the feedback stabilization of a class of diagonal infinite-dimensional boundary control systems in the presence of a time-varying delay in the boundary control input.\",\n \"Title: Augmented Reality, Cyber-Physical Systems, and Feedback Control for Additive Manufacturing: A Review.\\nYear: 2019\\n\\nAbstract: Our objective in this paper is to review the application of feedback ideas in the area of additive manufacturing. Both the application of feedback control to the 3D printing process and the application of feedback theory to enable users to interact better with machines are reviewed. Where appropriate, opportunities for future work are highlighted.\",\n \"Title: On L∞ string stability of nonlinear bidirectional asymmetric heterogeneous platoon systems\\nYear: 2019\\n\\nAbstract: This paper is concerned with the study of bidirectionally coupled platoon systems. The case considered is when the vehicles are heterogeneous and the coupling can be nonlinear and asymmetric. For such systems, a sufficient condition for L∞ string stability is presented. The effectiveness of our approach is illustrated via a numerical example, where it is shown how our result can be recast as an optimization problem, allowing to design the control protocol for each vehicle independently on the other vehicles and hence leading to a bottom-up approach for the design of string stable systems able to track a time-varying reference speed.\",\n \"Title: Some stability tests for switched descriptor systems\\nYear: 2019\\n\\nAbstract: In this paper we first derive some general Lyapunov based stability conditions for switched linear descriptor systems and illustrate them with a simple mechanical system. Next we develop simple conditions for specific classes of systems. In particular, we consider the important case when switching between a standard system and an index one descriptor system, and systems where switching occurs between an index one and an index two descriptor system. Examples are given to illustrate these results.\",\n \"Title: Control Law Realification for the Feedback Stabilization of a Class of Diagonal Infinite-Dimensional Systems with Delay Boundary Control\\nYear: 2019\\n\\nAbstract: Recently, a predictor feedback control strategy has been reported for the feedback stabilization of a class of infinite-dimensional Riesz-spectral boundary control systems exhibiting a finite number of unstable modes by means of a delay boundary control. Nevertheless, for real abstract boundary control systems exhibiting eigenstructures defined over the complex field, the direct application of suc...\",\n \"Title: On DICE-free Smart Cities, Particulate Matter, and Feedback-Enabled Access Control.\\nYear: 2019\\n\\nAbstract: The link between transport related emissions and human health is a major issue for city municipalities worldwide. PM emissions from exhaust and non-exhaust sources are one of the main worrying contributors to air-pollution. In this paper, we challenge the notion that a ban on DICE vehicles will result in clean and safe air in our cities, since emissions from tyres and other non-exhaust sources are expected to increase in the near future. To this end, we present data from the city of Dublin that document that the current amount of tyre-related PM emissions in the city might already be above or close to the levels deemed safe by the World Health Organization. As a solution to this problem, we present a feedback-enabled distributed access control mechanism and ride-sharing scheme to limit the amount of vehicles in a city and therefore maintain the amount of transport-related PM to safe levels. As shown in our simulations, our mechanism successfully restricts the number of cars in a city while ensuring fair access for its users.\",\n \"Title: Hysteresis-based supervisory control with application to non-pharmaceutical containment of COVID-19\\nYear: 2021\\n\\nAbstract: The recent COVID-19 outbreak has motivated an extensive development of non-pharmaceutical intervention policies for epidemics containment. While a total lockdown is a viable solution, interesting policies are those allowing some degree of normal functioning of the society, as this allows a continued, albeit reduced, economic activity and lessens the many societal problems associated with a prolonged lockdown. Recent studies have provided evidence that fast periodic alternation of lockdown and normal-functioning days may effectively lead to a good trade-off between outbreak abatement and economic activity. Nevertheless, the correct number of normal days to allocate within each period in such a way to guarantee the desired trade-off is a highly uncertain quantity that cannot be fixed a priori and that must rather be adapted online from measured data. This adaptation task, in turn, is still a largely open problem, and it is the subject of this work. In particular, we study a class of solutions based on hysteresis logic. First, in a rather general setting, we provide general convergence and performance guarantees on the evolution of the decision variable. Then, in a more specific context relevant for epidemic control, we derive a set of results characterizing robustness with respect to uncertainty and giving insight about how a priori knowledge about the controlled process may be used for fine-tuning the control parameters. Finally, we validate the results through numerical simulations tailored on the COVID-19 outbreak.\",\n \"Title: Integral action for setpoint regulation control of a reaction–diffusion equation in the presence of a state delay\\nYear: 2021\\n\\nAbstract: This paper is concerned with the regulation control of a one-dimensional reaction–diffusion equation in the presence of a state-delay in the reaction term. The objective is to achieve the PI regulation of the right Dirichlet trace with a command selected as the left Dirichlet trace. The control design strategy consists of the design of a PI controller on a finite dimensional truncated model obtained by spectral reduction. By an adequate selection of the number of modes of the original infinite-dimensional system, we show that the proposed control design procedure achieves both the exponential stabilization of the original infinite-dimensional system as well as the setpoint regulation of the right Dirichlet trace.\",\n \"Title: Access Control in Adversarial Environments for IoT-oriented Distributed Ledgers\\nYear: 2021\\n\\nAbstract: The surge of Internet of Things (IoT) applications requires distributed systems capable of securely exchanging messages and immutably recording data. While traditional blockchain architectures were not designed with IoT in mind, more recent Distributed Ledger Technologies (DLTs), which are not based on proof of work, can be considered as a solution to deal with the above requirements. However, wit...\",\n \"Title: Secure Access Control for DAG-Based Distributed Ledgers\\nYear: 2022\\n\\nAbstract: Access control is a fundamental component of the design of distributed ledgers, influencing many aspects of their functionality, such as fairness, efficiency, traditional notions of network security, and adversarial attacks such as Denial-of-Service (DoS) attacks.\\n<xref ref-type=\\\"fn\\\" rid=\\\"fn1\\\" xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"><sup>1</sup></xref>\\n In this work, we consider the security of a recently proposed access control protocol for directed acyclic graph-based distributed ledgers. We present a number of attack scenarios and potential vulnerabilities of the protocol and introduce a number of additional features which enhance its resilience. Specifically, a blacklisting algorithm, which is based on a reputation-weighted threshold, is introduced to handle both spamming and multirate malicious attackers. A solidification request component is also introduced to ensure the fairness and consistency of the network in the presence of attacks. Finally, a timestamp component is also introduced to maintain the consistency of the network in the presence of multirate attackers. Simulations to illustrate the efficacy and robustness of the revised protocol are also presented.\",\n \"Title: Pitchfork-bifurcation-based competitive and collaborative control of an E-bike system\\nYear: 2022\\n\\nAbstract: This paper is concerned with the design of a human-in-the-loop system for deployment on a smart pedelec (e-bike). From the control-theoretic perspective, the goal is not only to use the power assistance of the e-bike to reject disturbances along the route but also to manage the possibly competitive interactions between a human and the motor intervention. Managing the competitive/cooperative nature of the interactions is crucial for applications in which we wish to control physical aspects of the cycling behavior (e.g. heart rate and breathing rate). The basis of the control is a pitchfork bifurcation system, modeling the interactions, augmented using ideas from gain-scheduling. In vivo experiments have been conducted, showing the effectiveness of the proposed control strategy.\",\n \"Title: Electric Vehicle Ensembles for Quality of Service Based Mitigation of Renewable Production Risk\\nYear: 2022\\n\\nAbstract: While intermittent renewable power generation in the form of wind and solar PV has become a significant presence on the worlds electricity grids, the intermittency associated with this power supply introduces uncertainty into the grid operators task of matching supply with demand. A consequence of this intermittency is the large costs that accrue when supply is lower than forecasted and this cost ...\"\n]","isConversational":false},"profile_size":{"kind":"number","value":132,"string":"132"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":79,"string":"79"}}},{"rowIdx":80,"cells":{"question_id":{"kind":"string","value":"Mark F Flanagan"},"question":{"kind":"string","value":"Generate an abstract for the title \"A Versatile Variable Rate LDPC Codec Architecture\" using the following items: 1. LDPC codes\n2. System architecture\n3. Dynamic switching\n4. Rate compatibility\n5. Versatility"},"answer":{"kind":"string","value":"This paper presents a system architecture for low-density parity-check (LDPC) codes that allows dynamic switching of LDPC codes within the encoder and decoder without hardware modification of these modules. Thus, rate compatibility is facilitated without the performance degradation inherent in a puncture-based system. This versatility also allows the LDPC system to be used in a variety of applicat..."},"correct_answer":{"kind":"string","value":"This paper presents a system architecture for low-density parity-check (LDPC) codes that allows dynamic switching of LDPC codes within the encoder and decoder without hardware modification of these modules. Thus, rate compatibility is facilitated without the performance degradation inherent in a puncture-based system. This versatility also allows the LDPC system to be used in a variety of applicat..."},"documents":{"kind":"list like","value":["Title: Minimum Distance Distribution of Irregular Generalized LDPC Code Ensembles\nYear: 2013\n\nAbstract: In this paper, the minimum distance distribution of irregular generalized LDPC (GLDPC) code ensembles is investigated. Two classes of GLDPC code ensembles are analyzed; in one case, the Tanner graph is regular from the variable node perspective, and in the other case the Tanner graph is completely unstructured and irregular. In particular, for the former ensemble class we determine exactly which ensembles have minimum distance growing linearly with the block length with probability approaching unity with increasing block length. This work extends previous results concerning LDPC and regular GLDPC codes to the case where a hybrid mixture of check node types is used.","Title: Spectral Shape of Check-Hybrid GLDPC Codes\nYear: 2010\n\nAbstract: This paper analyzes the asymptotic exponent of both the weight spectrum and the stopping set size spectrum for a class of generalized low-density parity-check (GLDPC) codes. Specifically, all variable nodes (VNs) are assumed to have the same degree (regular VN set), while the check node (CN) set is assumed to be composed of a mixture of different linear block codes (hybrid CN set). A simple expression for the exponent (which is also referred to as the growth rate or the spectral shape) is developed. This expression is consistent with previous results, including the case where the normalized weight or stopping set size tends to zero. Furthermore, it is shown how certain symmetry properties of the local weight distribution at the CNs induce a symmetry in the overall weight spectral shape function.","Title: Linear-programming decoding of nonbinary linear codes\nYear: 2009\n\nAbstract: A framework for linear-programming (LP) decoding of nonbinary linear codes over rings is developed. This framework facilitates LP-based reception for coded modulation systems which use direct modulation mapping of coded symbols. It is proved that the resulting LP decoder has the \"maximum-likelihood (ML) certificate\" property. It is also shown that the decoder output is the lowest cost. pseudocodeword. Equivalence between pseudocodewords of the linear program and pseudocodewords of graph covers is proved. It is also proved that if the modulator-channel combination satisfies a particular symmetry condition, the codeword error rate performance is independent of the transmitted codeword. Two alternative polytopes for use with LP decoding are studied, and it is shown that for many classes of codes these polytopes yield a complexity advantage for decoding. These polytope representations lead to polynomial-time decoders for a wide variety of classical nonbinary linear codes. LP decoding performance is illustrated for the [11.6] ternary Golay code with ternary phase-shift keying (PSK) modulation over additive white Gaussian noise (AWGN), and in this case it is shown that the performance of the LP decoder is comparable to codeword-error-rate-optimum hard-decision-based decoding. LP decoding is also simulated for medium-length ternary and quaternary low-density parity-check (LDPC) codes with corresponding PSK modulations over AWGN.","Title: Growth rate of the weight distribution of doubly-generalized LDPC codes: general case and efficient evaluation\nYear: 2009\n\nAbstract: The growth rate of the weight distribution of irregular doubly-generalized LDPC (D-GLDPC) codes is developed and in the process, a new efficient numerical technique for its evaluation is presented. The solution involves simultaneous solution of a 4 à 4 system of polynomial equations. This represents the first efficient numerical technique for exact evaluation of the growth rate, even for LDPC codes. The technique is applied to two example D-GLDPC code ensembles.","Title: Network-turbo-coding-based cooperation with distributed space-time block codes\nYear: 2013\n\nAbstract: AbstractIn this paper, we propose a scheme to improve the performance of turbo-coded two-user cooperative uplink transmission. In the proposed scheme, each user transmits its partner's second parity frame in addition to its own, using a network-coded combination, which is further protected by a space-time block code. The proposed system is simulated in slow and fast fading environments. Numerical simulation results indicate that for slow fading, the proposed scheme can yield up to 20% increase in data throughput compared to the traditional distributed turbo coding, while simultaneously providing a gain of 0.7dB in bit error rate. This latter gain rises to approximately 2.5dB when a fast fading environment is considered. Furthermore, an outage probability analysis is conducted, which corroborates the simulated performance results.Copyright © 2014 John Wiley & Sons, Ltd.","Title: Factor graph based receiver design for PCC-coded BPSK transmissions over a frequency-selective fading channel\nYear: 2007\n\nAbstract: This paper presents an iterative receiver to detect and decode parallel concatenated convolutional (PCC) coded BPSK transmissions over a frequency-selective Rayleigh fading channel. The scheme generalises work by Valenti and Woerner to frequency- selective channels. A detailed derivation of the receiver from factor graph theory is presented. For the purposes of channel estimation, a Wiener filter based estimator is derived, and the interaction between the channel estimation procedure and the message-passing algorithm is illustrated. In particular it is shown that, in contrast to Valenti and Woerner's scheme, the pilot symbols appear as variables in the factor graph, leading to the insertion and removal of 'pilot symbol LLRs' in the receiver. Finally, the BER performance of the system is demonstrated through computer simulations. Copyright (C) 2007 John Wiley & Sons, Ltd.","Title: On a class of doubly-generalized LDPC codes with single parity-check variable nodes\nYear: 2009\n\nAbstract: A class of doubly-generalized low-density parity-check (D-GLDPC) codes, where single parity-check (SPC) codes are used as variable nodes (VNs), is investigated. An expression for the growth rate of the weight distribution of any D-GLDPC ensem ble with a uniform check node (CN) set is presented at first, together with an analytical technique for its efficient evaluation. These tools are then used for detailed analysis of a case study, namely, a rate-1/2 D-GLDPC ensemble where all the CNs are (7,4) Hamming codes and all the VNs are length-7 SPC codes. It is illustrated how the VN representations can heavily affect the code properties and how different VN representations can be combined within the same graph to enhance some of the code parameters. The analysis is conducted over the binary erasure channel. Interesting features of the new codes include the capability of achieving a good compromise between waterfall and error floor performance while preserving graphical regularity, and values of threshold outperforming LDPC counterparts.","Title: A Unified Framework for Linear-Programming Based Communication Receivers\nYear: 2011\n\nAbstract: It is shown that a large class of communication systems which admit a sum-product algorithm (SPA) based receiver also admit a corresponding linear-programming (LP) based receiver. The two receivers have a relationship defined by the local structure of the underlying graphical model, and are inhibited by the same phenomenon, which we call pseudoconfigurations. This concept is a generalization of th...","Title: Stability of Iterative Decoding of Multi-Edge Type Doubly-Generalized LDPC Codes Over the BEC\nYear: 2011\n\nAbstract: Using the EXIT chart approach, a necessary and sufficient condition is developed for the local stability of iterative decoding of multi-edge type (MET) doubly-generalized low-density parity-check (D-GLDPC) code ensembles. In such code ensembles, the use of arbitrary linear block codes as component codes is combined with the further design of local Tanner graph connectivity through the use of multiple edge types. The stability condition for these code ensembles is shown to be succinctly described in terms of the value of the spectral radius of an appropriately defined polynomial matrix.","Title: Multiple Cell Upset Correction in Memories Using Difference Set Codes.\nYear: 2012\n\nAbstract: Error Correction Codes (ECCs) are commonly used to protect memories from soft errors. As technology scales, Multiple Cell Upsets (MCUs) become more common and affect a larger number of cells. An option to protect memories against MCUs is to use advanced ECCs that can correct more than one error per word. In this area, the use of one step majority logic decodable codes has recently been proposed fo...","Title: Exploration of AWGNC and BSC Pseudocodeword Redundancy\nYear: 2010\n\nAbstract: The AWGNC, BSC, and max-fractional pseudocodeword redundancy of a code is\ndefined as the smallest number of rows in a parity-check matrix such that the\ncorresponding minimum pseudoweight is equal to the minimum Hamming distance of\nthe code. This paper provides new results on the AWGNC, BSC, and max-fractional\npseudocodeword redundancies of codes. The pseudocodeword redundancies for all\ncodes of small length (at most 9) are computed. Also, comprehensive results are\nprovided on the cases of cyclic codes of length at most 250 for which the\neigenvalue bound of Vontobel and Koetter is sharp.","Title: Spectral Shape of Doubly-Generalized LDPC Codes: Efficient and Exact Evaluation\nYear: 2012\n\nAbstract: This paper analyzes the asymptotic exponent of the weight spectrum for irregular doubly-generalized LDPC (D-GLDPC) codes. In the process, an efficient numerical technique for its evaluation is presented, involving the solution of a 4 $\\\\,\\\\,\\\\times$ 4 system of polynomial equations. The expression is consistent with previous results, including the case where the normalized weight or stopping set size tends to zero. The spectral shape is shown to admit a particularly simple form in the special case where all variable nodes are repetition codes of the same degree, a case which includes Tanner codes; for this case it is also shown how certain symmetry properties of the local weight distribution at the CNs induce a symmetry in the overall weight spectral shape function. Finally, using these new results, weight and stopping set size spectral shapes are evaluated for some example generalized and doubly-generalized LDPC code ensembles.","Title: On Joint Cryptographic Verification and Channel Decoding via the Maximum Likelihood Criterion.\nYear: 2012\n\nAbstract: The scenario is considered where a message, together with its message authentication code (MAC), is transmitted over a noisy channel. It is assumed that a forward error correcting channel code is used to reduce the error rate, but no repeat mechanism (ARQ) is used to correct the remaining errors. In such systems, uncorrected errors usually cause rejection of messages with an incorrect MAC. This pa...","Title: Lower Bounds on the Minimum Pseudodistance for Linear Codes with $q$-ary PSK Modulation over AWGN\nYear: 2008\n\nAbstract: We present lower bounds on the minimum pseu- docodeword effective Euclidean distance (or minimum \"pseu- dodistance\") for coded modulation systems using linear codes with q-ary phase-shift keying (PSK) modulation over the ad- ditive white Gaussian noise (AWGN) channel. These bounds apply to both binary and nonbinary coded modulation systems which use direct modulation mapping of coded symbols. The minimum pseudodistance may serve as a first-order measure of error-correcting performance for both linear-programming and message-passing based receivers. In the case of a linear- programming based receiver, the minimum pseudodistance may be used to form an exact bound on the codeword error rate of the system.","Title: Low Complexity Linear Programming Decoding of Nonbinary Linear Codes\nYear: 2010\n\nAbstract: Linear Programming (LP) decoding of Low-Density Parity-Check (LDPC) codes has\nattracted much attention in the research community in the past few years. The\naim of LP decoding is to develop an algorithm which has error-correcting\nperformance similar to that of the Sum-Product (SP) decoding algorithm, while\nat the same time it should be amenable to mathematical analysis. The LP\ndecoding algorithm has also been extended to nonbinary linear codes by Flanagan\net al. However, the most important problem with LP decoding for both binary and\nnonbinary linear codes is that the complexity of standard LP solvers such as\nthe simplex algorithm remain prohibitively large for codes of moderate to large\nblock length. To address this problem, Vontobel et al. proposed a low\ncomplexity LP decoding algorithm for binary linear codes which has complexity\nlinear in the block length. In this paper, we extend the latter work and\npropose a low-complexity LP decoding algorithm for nonbinary linear codes. We\nuse the LP formulation proposed by Flanagan et al. as a basis and derive a pair\nof primal-dual LP formulations. The dual LP is then used to develop the\nlow-complexity LP decoding algorithm for nonbinary linear codes. In contrast to\nthe binary low-complexity LP decoding algorithm, our proposed algorithm is not\ndirectly related to the nonbinary SP algorithm. Nevertheless, the complexity of\nthe proposed algorithm is linear in the block length and is limited mainly by\nthe maximum check node degree. As a proof of concept, we also present a\nsimulation result for a $[80,48]$ LDPC code defined over $\\mathbb{Z}_4$ using\nquaternary phase-shift keying over the AWGN channel, and we show that the\nerror-correcting performance of the proposed LP decoding algorithm is similar\nto that of the standard LP decoding using the simplex solver.","Title: Spectral graph analysis of quasi-cyclic codes\nYear: 2009\n\nAbstract: In this paper we analyze the bound on the additive white Gaussian noise channel (AWGNC) pseudo-weight of a (c, d)-regular linear block code based on the two largest values ¿1 > ¿2 of the eigenvalues of HTH: wp min > (H) ¿ n = 2c-¿2/¿1-¿2. In particular, we analyze (c, d)-regular quasi-cyclic (QC) codes of length rL described by J à L block parity-check matrices with circulant block entries of size r à r. We proceed by showing how the problem of computing the eigenvalues of the rL à rL matrix HTH can be reduced to the problem of computing eigenvalues for r matrices of size L à L. We also give a necessary condition for the bound to be attained for a circulant matrix H and show a few classes of cyclic codes satisfying this criterion.","Title: Joint Channel and Network Coding for Cooperative Diversity in a Shared-Relay Environment\nYear: 2010\n\nAbstract: In this paper we propose a cooperative diversity scheme for the communication model of two sources sharing a single relay. The scheme uses algebraic code superposition relaying in the multiple access fading channel to create spatial diversity under the constraint of limited communications resources. We also describe in detail a novel computationally efficient message passing algorithm at the destination's decoder which extracts the substantial spatial diversity contained in the code superposition and signal superposition. The decoder is based on a sliding window structure where certain a posteriori LLRs are retained to form a priori LLRs for the next decoding. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.","Title: Design of LDPC Code Ensembles with Fast Convergence Properties.\nYear: 2014\n\nAbstract: The design of low-density parity-check (LDPC) code ensembles optimized for a finite number of decoder iterations is investigated. Our approach employs EXIT chart analysis and differential evolution to design such ensembles for the binary erasure channel and additive white Gaussian noise channel. The error rates of codes optimized for various numbers of decoder iterations are compared and it is seen that in the cases considered, the best performance for a given number of decoder iterations is achieved by codes which are optimized for this particular number. The design of generalized LDPC (GLDPC) codes is also considered, showing that these structures can offer better performance than LDPC codes for low-iteration-number designs. Finally, it is illustrated that LDPC codes which are optimized for a small number of iterations exhibit significant deviations in terms of degree distribution and weight enumerators with respect to LDPC codes returned by more conventional design tools.","Title: Codeword-independent performance of nonbinary linear codes under linear-programming and sum-product decoding\nYear: 2008\n\nAbstract: A coded modulation system is considered in which nonbinary coded symbols are mapped directly to nonbinary modulation signals. It is proved that if the modulator-channel combination satisfies a particular symmetry condition, the codeword error rate performance is independent of the transmitted codeword. It is shown that this result holds for both linear-programming decoders and sum-product decoders. In particular, this provides a natural modulation mapping for nonbinary codes mapped to PSK constellations for transmission over memoryless channels such as AWGN channels or flat fading channels with AWGN.","Title: Linear-programming receivers\nYear: 2008\n\nAbstract: It is shown that any communication system which admits a sum-product (SP) receiver also admits a corresponding linear-programming (LP) receiver. The two receivers have a relationship defined by the local structure of the underlying graphical model, and are inhibited by the same phenomenon, which we call pseudoconfigurations. This concept is a generalization of the concept of pseudocodewords for linear codes. It is proved that the LP receiver has the dasiaoptimum certificatepsila property, and that the receiver output is the lowest cost pseudoconfiguration. Equivalence of graph-cover pseudoconfigurations and linear-programming pseudoconfigurations is also proved. While the LP receiver is generally more complex than the corresponding SP receiver, the LP receiver and its associated pseudoconfiguration structure provide an analytic tool for the analysis of SP receivers. As an example application, we show how the LP design technique may be applied to the problem of joint equalization and decoding.","Title: Error Detection in Majority Logic Decoding of Euclidean Geometry Low Density Parity Check (EG-LDPC) Codes\nYear: 2013\n\nAbstract: In a recent paper, a method was proposed to accelerate the majority logic decoding of difference set low density parity check codes. This is useful as majority logic decoding can be implemented serially with simple hardware but requires a large decoding time. For memory applications, this increases the memory access time. The method detects whether a word has errors in the first iterations of majority logic decoding, and when there are no errors the decoding ends without completing the rest of the iterations. Since most words in a memory will be error-free, the average decoding time is greatly reduced. In this brief, we study the application of a similar technique to a class of Euclidean geometry low density parity check (EG-LDPC) codes that are one step majority logic decodable. The results obtained show that the method is also effective for EG-LDPC codes. Extensive simulation results are given to accurately estimate the probability of error detection for different code sizes and numbers of errors.","Title: On the Pseudocodeword Redundancy of Binary Linear Codes\nYear: 2012\n\nAbstract: For a binary linear code, the pseudocodeword redundancy with respect to the additive white Gaussian noise channel, the binary symmetric channel, or the max-fractional weight is defined to be the smallest number of rows in a parity-check matrix such that the corresponding minimum pseudoweight is equal to the minimum Hamming distance of the code. It is shown that most codes do not have a finite pseudocodeword redundancy. Also, upper bounds on the pseudocodeword redundancy for some families of codes, including codes based on designs, are provided. The pseudocodeword redundancies for all codes of small length (at most 9) are computed. Furthermore, comprehensive results are provided on the cases of cyclic codes of length at most 250 for which the eigenvalue bound of Vontobel and Koetter is sharp.","Title: Serial Symbol-Reliability Based Algorithm for Decoding Non-Binary LDPC Codes\nYear: 2012\n\nAbstract: A symbol-reliability based decoding algorithm with serial schedule for non-binary low-density parity-check (LDPC) codes is presented. Performance results, together with implementation complexity analysis, are provided for different sample codes. The proposed algorithm achieves a similar gain to the min- max algorithm for codes with column weight dv ≥ 6, with lower complexity than previous symbol-reliability based algorithms.","Title: Exposing pseudoweight layers in regular LDPC code ensembles\nYear: 2009\n\nAbstract: A solution is presented for the asymptotic growth rate of the AWGN-pseudoweight distribution of regular low-density parity-check (LDPC) code ensembles for a selected graph cover degree M ¿1. The evaluation of the growth rate requires solution of a system of 2M +1 nonlinear equations in 2M +1 unknowns. Simulation results for the pseudoweight distribution of two regular LDPC code ensembles are presented for graph covers of low degree.","Title: On the pseudocodeword redundancy\nYear: 2010\n\nAbstract: We define the AWGNC, BSC, and max-fractional pseudocodeword redundancy of a\ncode as the smallest number of rows in a parity-check matrix such that the\ncorresponding minimum pseudoweight is equal to the minimum Hamming distance. We\nshow that most codes do not have a finite pseudocodeword redundancy. We also\nprovide bounds on the pseudocodeword redundancy for some families of codes,\nincluding codes based on designs.","Title: Low-Complexity LP Decoding of Nonbinary Linear Codes\nYear: 2012\n\nAbstract: Linear Programming (LP) decoding of Low-Density Parity-Check (LDPC) codes has attracted much attention in the research community in the past few years. LP decoding has been derived for binary and nonbinary linear codes. However, the most important problem with LP decoding for both binary and nonbinary linear codes is that the complexity of standard LP solvers such as the simplex algorithm remains prohibitively large for codes of moderate to large block length. To address this problem, two low-complexity LP (LCLP) decoding algorithms for binary linear codes have been proposed by Vontobel and Koetter, henceforth called the basic LCLP decoding algorithm and the subgradient LCLP decoding algorithm. In this paper, we generalize these LCLP decoding algorithms to nonbinary linear codes. The computational complexity per iteration of the proposed nonbinary LCLP decoding algorithms scales linearly with the block length of the code. A modified BCJR algorithm for efficient check-node calculations in the nonbinary basic LCLP decoding algorithm is also proposed, which has complexity linear in the check node degree. Several simulation results are presented for nonbinary LDPC codes defined over Z 4 , GF(4), and GF(8) using quaternary phase-shift keying and 8-phase-shift keying, respectively, over the AWGN channel. It is shown that for some group-structured LDPC codes, the error-correcting performance of the nonbinary LCLP decoding algorithms is similar to or better than that of the min-sum decoding algorithm.","Title: A Soft Decode-Compress-Forward Relaying Scheme for Cooperative Wireless Networks\nYear: 2013\n\nAbstract: This paper proposes a new technique for soft information relaying, which is based on a soft decode–compress–forward relay protocol. The proposed system provides a means of using distributed low-density parity-check (LDPC) coding in conjunction with higher order modulation, such as pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM), which is effective even under poor source–relay link conditions. Ordinarily, such schemes suffer from error propagation to the destination caused by incorrect decoding at the relay when the signal-to-noise ratio (SNR) on the source–relay link is low; however, our system avoids this problem by generating soft versions of the additional (parity-bearing) PAM symbols for transmission from the relay. The proposed technique of soft compression does not suffer from parity log-likelihood ratios (LLRs) converging to zero, as do many soft re-encoding techniques for turbo and LDPC codes. In the case of Gray-coded PAM/QAM signaling, we also propose a method of performing exact expectation-based soft modulation with low computational complexity. Furthermore, we propose a new model, which we refer to as the soft scalar model, for the overall source-to-destination channel encountered by the constellation symbols, and this model is used at the destination to compute LLRs for joint decoding of the distributed LDPC code. Simulation results demonstrate that the proposed scheme can provide good coding gain, diversity gain, and spectral efficiency under poor source–relay SNR conditions.","Title: LDPC coding with soft information relaying in cooperative wireless networks\nYear: 2013\n\nAbstract: This paper investigates soft information relaying (SIR) for low-density parity-check (LDPC) coded transmission in wireless networks. We introduce a new scheme for soft parity symbol generation at the relay, which features two key strategies: a two-step soft parity generation process, and a prescaling technique. The two-step soft parity generation procedure is designed to allow efficient relay processing, while yielding an overall (i.e., destination) parity-check matrix structure with desirable properties. The pre-scaling method prevents the amplitudes of generated soft symbols successively converging to zero, as happens with some existing soft forwarding methods. Finally, we propose an appropriate LLR former at the destination which is tailored to the proposed soft parity generation technique. Simulation results demonstrate that the proposed relay protocol yields an improved BER performance compared to competitive schemes proposed in the literature.","Title: Low-Density Lattice Coded Relaying with Joint Iterative Decoding\nYear: 2015\n\nAbstract: Low-density lattice codes (LDLCs) are known for their high decoding efficiency and near-capacity performance on point-to-point Gaussian channels. In this paper, we present a distributed LDLC-based cooperative relaying scheme for the multiple-access relay channel (MARC). The relay node decodes LDLC coded packets from two sources and forwards a networkcoded combination to the destination. At the destination, a joint iterative decoding structure is designed to exploit the diversity gain as well as coding gain. For the LDLC-based network coding operation at the relay, we consider two alternative methods which offer a tradeoff between implementation complexity and performance, called superposition LDLC (S-LDLC) and moduloaddition LDLC (MA-LDLC). Soft symbol relaying is considered as an alternative to hard decision relaying which is capable of reducing the effect of error propagation at the relay. Simulation results show that the proposed scheme can provide greater diversity gain and up to 6.2 dB coding gain when compared with non-cooperative LDLC coding and uncoded network-coded transmission. The proposed scheme also achieves 2.5 dB gain over network-turbo-coded cooperation, for the same code rate and overall transmitted power. Also, soft symbol relaying is shown to provide approximately 2 dB gain over hard decision relaying when the source-relay link suffers from deep fading.","Title: Distributed Low-Density Lattice Codes\nYear: 2016\n\nAbstract: This letter presents a novel distributed LDLC (D-LDLC) relaying scheme for the classical relay channel. The relay node decodes LDLC packets from the source and forwards an additional parity message to the destination. The destination then performs joint decoding in order to exploit the available coding gain as well as diversity gain. First, assuming AWGN links, density evolution is used to optimize the noise threshold of the overall parity-check matrix, and this method is shown to produce good finite-length D-LDLC designs. Then, we provide results for the optimized D-LDLCs under Rayleigh fading channel conditions. Joint decoding based on D-LDLC is shown to provide approximately 3 dB gain over distributed 4-PAM turbo codes under the same conditions (data rate and overall transmission power).","Title: Simultaneous Uplink/Downlink Transmission Using Full-Duplex Single-RF MIMO.\nYear: 2016\n\nAbstract: In this letter, we introduce a full-duplex protocol for simultaneous transmission between the uplink and the downlink of cellular networks. The protocol takes advantage of the inactive antenna(s) in multiple-input-multiple-output (MIMO) systems with a single active radio frequency (RF) front-end. More precisely, for the downlink transmissions, we make use of spatial modulation (SM), and for the uplink, we make use of the coordinate-interleaved orthogonal design (CIOD)-based space-time block code (STBC). We provide accurate mathematical expressions for evaluating the error-performances and the achievable diversity order at the base station (BS) and at the mobile terminal (MT) in the presence of self-interference. Our results demonstrate clearly the potential of SM and CIOD for full-duplex operation.","Title: LDPC coded soft forwarding with network coding for the two-way relay channel\nYear: 2014\n\nAbstract: This paper investigates a low-density parity-check (LDPC) coded soft-decode-and-forward (SDF) relaying protocol for a two way relay channel (TWRC). In this SDF protocol, the relay evaluates the reliabilities, expressed as log-likelihood ratios (LLRs), of the received signals from the two sources. The relay then forwards a network-coded combination of the parity symbols of both sources, but in the “soft” domain to avoid error propagation from the relay. We introduce a model for the effective noise experienced by the soft network coded symbols, constituting the new parameters of soft scalar and soft error; this model is then used to compute the log-likelihood ratios (LLRs) at the destination. To facilitate this latter computation, we have derived an analytical expression for soft error variance, as well as a simplified expression based on a common assumption on the statistical behavior of the LLRs. This enables low-complexity computation and tracking of the soft error variance on-the-fly. The proposed system outperforms standard competing schemes reported in the literature in terms of error rate performance over Rayleigh fading links.","Title: A multilevel soft quantize-and-forward scheme for multiple access relay systems\nYear: 2014\n\nAbstract: This paper proposes the novel technique of multilevel threshold based soft quantization (MLT-SQ) for a multiple access relay system (MARS). The scheme is suitable for systems using binary phase-shift keying (BPSK) and network coding at the relay. In the proposed MLT-SQ protocol, the relay evaluates the reliabilities, expressed as log-likelihood ratios (LLRs), of the received signals from the two sources. It then computes the LLRs of the network-coded packet and quantizes these using a set of optimized multilevel thresholds, forwarding the resulting “quantized soft symbols” to the destination. We provide the derivation for the bit error rate (BER) at the destination, based on which we optimize the multilevel thresholds to minimize the BER. Compared to competing schemes, the performance of our system is superior in terms of BER when the same amount of channel state information (CSI) is exploited.","Title: An Efficient Joint Channel-Network Decoder for Multiuser Diversity Network Codes With LDPC Coding.\nYear: 2016\n\nAbstract: Diversity network codes (DNCs) were recently proposed for multiuser cooperative networks, where nonbinary network codes are superimposed over channel codes to yield high diversity gains. In this letter, we present a joint iterative channel-network decoder for use at the base station in a system employing a DNC. The scheme is based on hybrid soft/hard message passing between constituent low-complexity low-density parity-check (LDPC) decoders. It is shown that the formation of the extrinsic log-likelihood ratios to be passed between the LDPC decoders has a low-complexity implementation involving a set of permutation operations together with the well-known Jacobian logarithm. The proposed joint channel-network decoder has a significantly reduced complexity compared with the decoding structure originally presented for maximum-diversity-achieving DNCs, and achieves significant coding gain as well as full diversity gain.","Title: Efficient and Exact Evaluation of the Weight Spectral Shape and Typical Minimum Distance of Protograph LDPC Codes.\nYear: 2016\n\nAbstract: In this letter, an analytical method for evaluating the weight spectral shape of a nonbinary protograph low-density parity-check code ensemble is provided. This method, which requires simultaneous solution of a system of equations, is more efficient to implement than the existing methods that require the numerical solution of a high-dimensional maximization problem. It is also shown that by adding a single equation to the proposed system, it is possible to directly solve for the typical minimum distance of the ensemble. This makes the proposed method particularly useful for the ensemble design scenario where a constraint is placed on the typical minimum distance. The proposed method is verified through the evaluation of the weight spectral shape of some example protograph ensembles.","Title: A Virtual Full Duplex Distributed Spatial Modulation Technique For Relay Networks\nYear: 2016\n\nAbstract: Spatial modulation, a multiple-input multipleoutput (MIMO) technology which uses the antenna index to transmit part of the incoming data, is an attractive way to reduce the energy cost and transceiver complexity in future wireless networks. In particular, the recently proposed technique of distributed spatial modulation (DSM) for relay networks can lead to better spectral efficiency, as it allows the relays to transmit their own data while simultaneously relaying the data of the source. A new distributed spatial modulation protocol is introduced in this paper which achieves virtual full duplex (VFD) communication. In this protocol, the source and relays transmit their own data in every time slot; thus, the spectral efficiency is significantly improved compared to conventional DSM. Simulation results indicate that at high signal-to-noise ratio (SNR), the proposed protocol has similar bit error rate (BER) performance versus SNR-per-bit compared to the standard full duplex relaying protocol of successive relaying; however, in contrast to successive relaying, the relays are simultaneously transmitting their own data, which is received at the destination with an error rate similar to that of the source's data.","Title: On Generalized Spatial Modulation For Multiuser Wireless Communications\nYear: 2017\n\nAbstract: The recently proposed multiple-input multiple-output (MIMO) technique of spatial modulation (SM) has attracted a good deal of attention due to its low implementation and computational complexity, and the spectral efficiency and energy efficiency gains it offers over many conventional MIMO schemes. There has been some progress made in applying SM to multiuser scenarios, including a proposed precoding scheme to eliminate the Multiuser Interference (MUI) associated with multiuser environments. A generalized technique for SM has also been proposed that promises further spectral efficiency gains over conventional SM. This paper proposes a precoding scheme to eliminate MUI in a generalized spatial modulation (GSM) scenario, thereby allowing individual users to employ a single-user Maximum Likelihood optimum detector. An interference-aware multiuser detection scheme is developed and the performance of both schemes is compared. The effect of precoder power normalization on the error rate performance is also explored in detail. Precoding is found to facilitate less complex detection and superior error rate performance in the multiuser GSM context.","Title: Physical-layer network coded QAM with trellis shaping for the two-way relay channel\nYear: 2016\n\nAbstract: Physical-layer network coding (PNC) allows to improve the throughput on the two-way relay channel (TWRC). PNC systems using higher-order modulation present some challenges regarding how to design the PNC mapping at the relay. With higher-order modulation it is also desirable to use constellation shaping which allows to minimize the average transmitted energy. In this paper, we show how low-complexity trellis shaping can be used to provide constellation shaping both at the user nodes and at the relay node. The proposed technique works specifically for sign bit shaping and M-ary quadrature amplitude modulation (QAM). Simulation results show that the proposed scheme provides a significantly increased performance in terms of the achievable BER, with 5.3dB shaping gain available at a BER of 10\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">-3</sup>\n in the case of 256-QAM signaling.","Title: Non-Binary Ldpc Codes For Orthogonal Modulations: Analysis And Code Design\nYear: 2017\n\nAbstract: In this paper, we present a low-density parity-check coded modulation approach addressing orthogonal modulations with moderate order (between 8 and 32) over the additive white Gaussian noise channel. The proposed design is based on a constrained optimization of a non-binary low-density parity-check ensemble degree distribution, where the iterative decoding threshold is optimized via extrinsic information transfer analysis while restricting the search to degree distributions that target low error floors. For various orthogonal modulation orders, we provide useful approximations to the extrinsic information transfer functions, which enable a fast optimization with respect to the iterative decoding threshold. The approach is validated via codeword error rate Monte Carlo simulations and complemented by an error floor analysis, showing gains up to 0.8 dB at a codeword error rate of 10(-4) with respect to existing designs, down to information block lengths as short as 192 bits.","Title: A low-complexity correlation-based time skew estimation technique for time-interleaved SAR ADCs\nYear: 2017\n\nAbstract: This paper presents a technique to estimate the time skew in time-interleaved ADCs. The proposed method estimates all of the time skew parameters jointly based on observations from a bank of correlators. The proposed method works for an arbitrary number of sub-ADCs. For implementation of the correlator bank, we propose the use of Mitchell's logarithmic multiplier and a hardware reuse mechanism, thereby reducing the complexity and power consumption. Also, we explain why blind estimation techniques alone (including the proposed one) are not always sufficient for time skew estimation for certain classes of input signal; for the proposed approach, however, a simple modification to the analogue circuit (suitable for SAR ADCs) is shown to successfully deal with such problems, with only a minor penalty in power and area. The technique is verified by extensive simulations including a spectrally rich input signal in which an MTPR (multi-tone power ratio) improvement from 29dB to 62dB was achieved for a TIADC system having 16 sub-ADCs.","Title: Transmit Antenna Selection for Physical-Layer Network Coding Based on Euclidean Distance.\nYear: 2017\n\nAbstract: Physical-layer network coding (PNC) is now well-known as a potential candidate for delay-sensitive and spectrally efficient communication applications, especially in two-way relay channels (TWRCs). In this paper, we present the error performance analysis of a multiple-input single-output (MISO) fixed network coding (FNC) system with two different transmit antenna selection (TAS) schemes. For the first scheme, where the antenna selection is performed based on the strongest channel, we derive a tight closed-form upper bound on the average symbol error rate (SER) with M-ary modulation and show that the system achieves a diversity order of 1 for M > 2. Next, we propose a Euclidean distance (ED) based antenna selection scheme which outperforms the first scheme in terms of error performance and is shown to achieve a diversity order lower bounded by the minimum of the number of antennas at the two users.","Title: A Generic Foreground Calibration Algorithm For ADCs with Nonlinear Impairments.\nYear: 2018\n\nAbstract: This paper presents a generic foreground calibration algorithm that estimates and corrects memoryless nonlinear impairments in both single channel and time-interleaved analog-to-digital converters (TIADCs), and which is capable of correcting for amplifier nonlinearity, comparator offsets, and capacitance mismatch for each channel. It operates by generating, and then using, a look-up table which ma...","Title: Wireless-Powered Distributed Spatial Modulation With Energy Recycling and Finite-Energy Storage.\nYear: 2018\n\nAbstract: The distributed spatial modulation (DSM) protocol, which allows relays to forward the source's data while simultaneously allowing the relays to transmit their own data, has been proposed by Narayanan et al. In this paper, we introduce two new protocols for enabling the DSM, consisting of single-antenna network nodes, with simultaneous wireless information and power transfer capability: power split...","Title: Gibbs Sampling Aided Throughput Improvement for Next-Generation Wi-Fi\nYear: 2018\n\nAbstract: Wireless communications, and in particular wireless local area network (WLAN) technology, has undergone a tremendous evolution in the past decades. After the release of the WLAN standard IEEE 802.11a/b in 1999, Wi-Fi technology soon became pervasive, thanks mainly to its deployment on the unlicensed ISM band. However, high traffic, especially in hotspots and areas with dense deployment of Wi-Fi access points (APs) (e.g., stations, airports, etc.) has caused major issues and a severe degradation of communications quality. The latest WLAN standards (e.g., 802.11ac, 802.11ax) have largely succeeded in improving the link quality and data rate by adopting state-of-the-art PHY layer technologies, e.g., OFDMA, MU-MIMO. However, improvement of the MAC layer in these standards is not noticeable due to restrictions such as hardware limitation and backward compatibility issues for legacy APs. As an effort to improve the MAC layer for the next-generation WLAN standard, in this paper we propose a simple algorithm with low computational complexity for channel selection in Wi-Fi networks. The main idea is to take advantage of the potential of the IEEE 802.11ax MAC to avoid major standard modifications. For this purpose, we employ the channel utilization ratio (CUR), which is measured periodically by each AP based on its channel sensing. Time-averaged CUR values are weighted based on a Gibbs sampling approach and a probability associated to each channel is updated. Finally, a channel is selected based on the aforementioned probabilities in predefined time slots. Simulation results show that the proposed approach can improve the system throughput by up to 5% and transmission delay by up to 20%.","Title: Satisfaction Based Channel Allocation Scheme for Self-Organization in Heterogeneous Networks.\nYear: 2018\n\nAbstract: The next-generation wireless networks are expected to become denser and more heterogeneous in order to boost the network capacity. However, densely deployed base stations (BSs) in heterogeneous networks (HetNets) can give rise to interference. On the other hand, a limited number of channels is allocated within the HetNets. Therefore, the efficient assignment of channels among BSs is considered to be an important issue. Furthermore, the density and heterogeneity of the networks motivate self-organizing resource management techniques. In this paper, we address the problem of channel allocation in HetNets, and propose a satisfaction based channel allocation algorithm. The problem is modeled as a game in satisfaction form, in which BSs act as the players with the constraint given by the loads at the BSs. The objective is to meet the data rate requirements of user equipments. In this regard, the BSs aim at seeking a satisfaction solution rather than the optimal one. In order to learn the satisfaction equilibrium, a fully distributed algorithm based on the individual utility is applied. Simulation results show that the proposed approach can increase the average BS's throughput compared to the benchmark algorithms.","Title: On the Performance of NOMA-based Cooperative Relaying with Receive Diversity\nYear: 2019\n\nAbstract: Non-orthogonal multiple access (NOMA) is widely recognized as a potential multiple access (MA) technology for efficient spectrum utilization in the fifth-generation (5G) wireless standard. In this paper, we present the achievable sum rate analysis of a cooperative relaying system (CRS) using NOMA with two different receive diversity schemes - selection combining (SC), where the antenna with highest instantaneous signal-to-noise ratio (SNR) is selected, and maximal-ratio combining (MRC). We also present the outage probability and diversity analysis for the CRS-NOMA system. Analytical results confirm that the CRS-NOMA system outperforms the CRS with conventional orthogonal multiple access (OMA) by achieving higher spectral efficiency at high transmit SNR and achieves a full diversity order.","Title: On the Performance of Spatial Modulation MIMO for Full-Duplex Relay Networks.\nYear: 2017\n\nAbstract: In this paper, we investigate, for the first time, the performance of a full-duplex (FD) relaying protocol, where a single-RF spatial modulation (SM) multiple-input multiple-output (MIMO) system is employed at the relay node. We refer to this protocol as SM-aided FD relaying (SM-FDR). At the destination, a demodulator that takes advantage of the direct connectivity between the source and destinati...","Title: Blind SAR ADC capacitor mismatch calibration\nYear: 2017\n\nAbstract: This paper presents an all-digital background blind calibration technique for the capacitor mismatch problem in SAR ADCs. It utilizes the redundancy offered using a sub-radix-2 DAC architecture to blindly estimate the mismatch and the assigned weight for each comparator decision. The weights are estimated by building partial histogram windows for the comparator decision vectors. To remove the dependency on the input signal's probability density function, the histogram windows are normalized with respect to their peaks. Matlab simulation results show that an ENOB within 0.12bit of the optimal is attained using the proposed algorithm.","Title: User-Antenna Selection for Physical-Layer Network Coding based on Euclidean Distance.\nYear: 2019\n\nAbstract: In this paper, we present the error performance analysis of a multiple-input multiple-output (MIMO) physical-layer network coding (PNC) system with two different user-antenna selection (AS) schemes in asymmetric channel conditions. For the first antenna selection scheme (AS1), where the user antenna is selected in order to maximize the overall channel gain between the user and the relay, we give a...","Title: A High-Precision Time Skew Estimation and Correction Technique for Time-Interleaved ADCs\nYear: 2019\n\nAbstract: This paper presents an all-digital background calibration technique for the time skew mismatch in time-interleaved ADCs (TIADCs). The technique jointly estimates all of the time skew values by processing the outputs of a bank of correlators. A low-complexity sampling sequence intervention technique, suitable for successive approximation register (SAR) ADC architectures, is proposed to overcome the limitations associated with blind estimation. A two-stage digital correction mechanism based on the Taylor series is proposed to satisfy the target high-precision correction. A quantitative study is performed regarding the requirements imposed on the digital correction circuit in order to satisfy the target performance and yield, and a corresponding filter design method is proposed, which is tailored to meet these requirements. Mitchell’s logarithmic multiplier is adopted for the implementation of the principal multipliers in both the estimation and correction mechanisms, leading to a 25% area and power reduction in the estimation circuit. The proposed calibration is synthesized using a TSMC 28-nm HPL process targeting a 2.4-GHz sampling frequency for an eight-sub-ADC system. The calibration block occupies 0.03 mm\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">2</sup>\n and consumes 11 mW. The algorithm maintains the SNDR above 65 dB for a sinusoidal input within the target bandwidth.","Title: On the Secrecy Rate of Downlink NOMA in Underlay Spectrum Sharing with Imperfect CSI: Invited Paper\nYear: 2021\n\nAbstract: In this paper, we present the ergodic sum secrecy rate (ESSR) analysis of an underlay spectrum sharing nonorthogonal multiple access (NOMA) system. We consider the scenario where the power transmitted by the secondary transmitter (ST) is constrained by the peak tolerable interference at multiple primary receivers (PRs) as well as the maximum transmit power of the ST. The effect of channel estimati...","Title: On Characterizing The Capacity Region Of Massive Mimo Systems With Joint Power Constraints\nYear: 2021\n\nAbstract: In this paper we consider the problem of computing the capacity of multi-user Gaussian MIMO systems under multiple linear transmit covariance constraints (LTCCs). These LTCCs are general enough to include many transmit power constraints such as sum power constraint (SPC) or per-antenna power constraint (PAPC) as special cases. For the considered MIMO systems with multiple LTCCs, existing solutions are based on subgradient or gradient descent methods, which are known to have slow convergence in general and are therefore not applicable to massive MIMO systems. In contrast, we propose a low-complexity semi-closed-form approach to computing the MIMO capacity for the system of interest. To this end, the considered problem in the broadcast channel is transformed into an equivalent minimax problem in the multiple access channel. The special structure of the minimax problem allows us to derive water-filling-like algorithms based on a novel combination of alternating optimization and concave-convex procedure. For the important case of joint SPC and PAPC, we also propose analytical expressions to find the optimal covariance matrix. Extensive analytical and numerical results are provided to demonstrate the effectiveness of our approach under various massive MIMO system settings.","Title: On the Effective Rate of NOMA in Underlay Spectrum Sharing\nYear: 2021\n\nAbstract: In this paper, we present the delay-constrained performance analysis of a multi-antenna-assisted multiuser non-orthogonal multiple access (NOMA) based spectrum sharing system over Rayleigh fading channels. We derive analytical expressions for the sum effective rate (ER) for the downlink NOMA system under a peak interference constraint. In particular, we show the effect of the availability of diffe...","Title: On the Achievable Sum-rate of the RIS-aided MIMO Broadcast Channel : Invited Paper\nYear: 2021\n\nAbstract: Reconfigurable intelligent surfaces (RISs) represent a new technology that can shape the radio wave propagation and thus offers a great variety of possible performance and implementation gains. Motivated by this, we investigate the achievable sum-rate optimization in a broadcast channel (BC) that is equipped with an RIS. We exploit the well-known duality between the Gaussian multiple-input multipl...","Title: RIS-Assisted Receive Quadrature Space-Shift Keying: A New Paradigm and Performance Analysis\nYear: 2022\n\nAbstract: Reconfigurable intelligent surfaces (RISs) represent a promising candidate for sixth-generation (6G) wireless networks, as the RIS technology provides a new solution to control the propagation channel in order to improve the efficiency of a wireless link through enhancing the received signal power. In this paper, we propose RIS-assisted receive quadrature space shift keying (RIS-RQSSK), which enhances the spectral efficiency of an RIS-based index modulation (IM) system by using the real and imaginary dimensions independently for the purpose of IM. Therefore, the error rate performance of the system is improved as all RIS elements reflect the incident transmit signal toward both selected receive antennas. At the receiver, a low-complexity but effective greedy detector (GD) can be employed which determines the maximum energy per dimension at the receive antennas. A max-min optimization problem is defined to maximize the received signal-to-noise ratio (SNR) components at both selected receive antennas; an analytical solution is provided based on Lagrange duality. In particular, the multi-variable optimization problem is shown to reduce to the solution of a single-variable equation, which results in a very simple design procedure. In addition, we investigate the average bit error probability (ABEP) of the proposed RIS-RQSSK system and derive a closed-form approximate upper bound on the ABEP. We also provide extensive numerical simulations to validate our derivations. Numerical results show that the proposed RIS-RQSSK scheme substantially outperforms recent prominent benchmark schemes. This enhancement considerably increases with an increasing number of receive antennas.","Title: Low-Complexity Joint CFO and Channel Estimation for RIS-Aided OFDM Systems\nYear: 2022\n\nAbstract: Accurate channel estimation is essential for achieving the performance gains offered by reconfigurable intelligent surface (RIS)-aided wireless communications. A variety of channel estimation methods have been proposed for such systems; however, none of the existing methods takes into account the effect of synchronization errors such as carrier frequency offset (CFO). In general, CFO can significa...","Title: Transceiver Design and Power Control for Full-Duplex Ultra-Reliable Low-Latency Communication Systems\nYear: 2022\n\nAbstract: Ultra-reliable low-latency communication (URLLC) is one of the most important components in the fifth generation (5G) cellular networks for realizing mission-critical applications. In this paper, we jointly optimize the transceiver design and decoding error probability (DEP) of a full-duplex (FD) URLLC system, where the base station (BS) operates in FD mode, while the uplink (UL) and downlink (DL) users work in half-duplex (HD) mode. Accordingly, an optimization problem is formulated to maximize the achievable total (UL plus DL) rate for an FD URLLC system under finite blocklength, subject to the end-to-end (E2E) reliability constraint from the UL user to each DL user and the total transmission power constraint at the UL user and at the BS. We analyze the problem structure and convexify the problem by approximating the channel dispersion in scenarios of high and mid-to-high signal-to-interference plus noise ratio (SINR) regimes, respectively. Next, efficient iterative algorithms are proposed to find the near-optimal power allocation for the UL user and transceiver weights for the BS. Furthermore, closed-form expressions of the transceiver weights are derived, and the convergence of the proposed algorithms is proved. Simulation examples demonstrate the impact of the code blocklength, number of DL users, transmitter/receiver distortion and DEP threshold on the system performance.","Title: On the MIMO Capacity With Joint Sum and Per-Antenna Power Constraints: A New Efficient Numerical Method\nYear: 2022\n\nAbstract: We propose a semi-closed-form solution to the problem of computing the capacity and optimal signaling for a Gaussian MIMO channel under a joint sum power constraint (SPC) and per-antenna power constraint (PAPC). Existing efficient solutions to this fundamental problem are only applicable to some special cases: multiple-input single-output (MISO) systems, or full column rank MIMO channels with sufficiently high transmit power, or full-rank optimal signaling. For the general case, we present an efficient numerical method to solve the considered problem which does not make any assumptions on the rank of the channel matrix or the maximum transmit power. To achieve this, the considered problem is transformed into an equivalent minimax problem. We then exploit the special structure of the minimax problem to derive a closed-form solution based on a concave-convex procedure (CCP)-like algorithm. Extensive simulation results show that our proposed algorithm outperforms the existing solutions in terms of complexity and generality.","Title: Context-Based Semantic Communication via Dynamic Programming\nYear: 2022\n\nAbstract: Standard digital communication techniques allow us to set aside the meaning of the messages to concentrate on the transmission of bits efficiently and reliably. However, with the integration of artificial intelligence into communications technology and the merging of communication and computation within devices, increasing evidence suggests that the semantic aspect of communication cannot be set aside. We propose a part-of-speech-based encoding strategy and context-based decoding strategies, in which various deep learning models are presented to learn the semantic and contextual features as background knowledge. With the background knowledge, our strategies can be applied to some non-jointly-designed communication scenarios with uncertainty. We compare the performances of two proposed decoding strategies, the deep learning models of which are different, to provide model-choice design guidelines in accordance with specific communication conditions. Further, we discuss the impact of several parameters on the performance of our strategies, such as the size of the context window and the size of the feature window. Simulation results indicate the effectiveness and the reliability of our strategies in terms of decreasing the number of bits used to transmit messages and increasing the semantic accuracy between transmitted messages and recovered messages.","Title: Joint power and blocklength optimization for RIS-aided multiple-access downlink ultra-reliable low-latency communication\nYear: 2022\n\nAbstract: Ultra-reliable low-latency communication (URLLC) has gained significant interest since it deals with short packet transmission adopted to reduce latency; however, this implies that the conventional Shannon capacity formula is not applicable, and the achievable data rate becomes a complex function of the decoding error probability and blocklength. This paper studies URLLC transmission using a time-division multiple access scheme with an arbitrary number of actuators utilising a reconfigurable intelligent surface. The authors optimisze the weighted sum rate of this system subject to reliability, total energy, and latency constraints. For the blocklength allocation in a scenario where each actuator is allocated equal power, a closed-form analytical solution is provided. Also, for the case of joint optimization of the blocklength and power of each actuator, an analytical solution is provided for the case of two actuators, while an iterative sequential quadratic programing method is adopted for the case of an arbitrary number of actuators. The proposed methodology provides a low-complexity, fast solution, which is more efficient than using exhaustive search techniques. The results show that in some cases, optimization of the blocklength provides a near-optimal solution at low complexity, while jointly optimising the blocklength and the power per actuator has an improved performance at the cost of additional complexity."],"string":"[\n \"Title: Minimum Distance Distribution of Irregular Generalized LDPC Code Ensembles\\nYear: 2013\\n\\nAbstract: In this paper, the minimum distance distribution of irregular generalized LDPC (GLDPC) code ensembles is investigated. Two classes of GLDPC code ensembles are analyzed; in one case, the Tanner graph is regular from the variable node perspective, and in the other case the Tanner graph is completely unstructured and irregular. In particular, for the former ensemble class we determine exactly which ensembles have minimum distance growing linearly with the block length with probability approaching unity with increasing block length. This work extends previous results concerning LDPC and regular GLDPC codes to the case where a hybrid mixture of check node types is used.\",\n \"Title: Spectral Shape of Check-Hybrid GLDPC Codes\\nYear: 2010\\n\\nAbstract: This paper analyzes the asymptotic exponent of both the weight spectrum and the stopping set size spectrum for a class of generalized low-density parity-check (GLDPC) codes. Specifically, all variable nodes (VNs) are assumed to have the same degree (regular VN set), while the check node (CN) set is assumed to be composed of a mixture of different linear block codes (hybrid CN set). A simple expression for the exponent (which is also referred to as the growth rate or the spectral shape) is developed. This expression is consistent with previous results, including the case where the normalized weight or stopping set size tends to zero. Furthermore, it is shown how certain symmetry properties of the local weight distribution at the CNs induce a symmetry in the overall weight spectral shape function.\",\n \"Title: Linear-programming decoding of nonbinary linear codes\\nYear: 2009\\n\\nAbstract: A framework for linear-programming (LP) decoding of nonbinary linear codes over rings is developed. This framework facilitates LP-based reception for coded modulation systems which use direct modulation mapping of coded symbols. It is proved that the resulting LP decoder has the \\\"maximum-likelihood (ML) certificate\\\" property. It is also shown that the decoder output is the lowest cost. pseudocodeword. Equivalence between pseudocodewords of the linear program and pseudocodewords of graph covers is proved. It is also proved that if the modulator-channel combination satisfies a particular symmetry condition, the codeword error rate performance is independent of the transmitted codeword. Two alternative polytopes for use with LP decoding are studied, and it is shown that for many classes of codes these polytopes yield a complexity advantage for decoding. These polytope representations lead to polynomial-time decoders for a wide variety of classical nonbinary linear codes. LP decoding performance is illustrated for the [11.6] ternary Golay code with ternary phase-shift keying (PSK) modulation over additive white Gaussian noise (AWGN), and in this case it is shown that the performance of the LP decoder is comparable to codeword-error-rate-optimum hard-decision-based decoding. LP decoding is also simulated for medium-length ternary and quaternary low-density parity-check (LDPC) codes with corresponding PSK modulations over AWGN.\",\n \"Title: Growth rate of the weight distribution of doubly-generalized LDPC codes: general case and efficient evaluation\\nYear: 2009\\n\\nAbstract: The growth rate of the weight distribution of irregular doubly-generalized LDPC (D-GLDPC) codes is developed and in the process, a new efficient numerical technique for its evaluation is presented. The solution involves simultaneous solution of a 4 à 4 system of polynomial equations. This represents the first efficient numerical technique for exact evaluation of the growth rate, even for LDPC codes. The technique is applied to two example D-GLDPC code ensembles.\",\n \"Title: Network-turbo-coding-based cooperation with distributed space-time block codes\\nYear: 2013\\n\\nAbstract: AbstractIn this paper, we propose a scheme to improve the performance of turbo-coded two-user cooperative uplink transmission. In the proposed scheme, each user transmits its partner's second parity frame in addition to its own, using a network-coded combination, which is further protected by a space-time block code. The proposed system is simulated in slow and fast fading environments. Numerical simulation results indicate that for slow fading, the proposed scheme can yield up to 20% increase in data throughput compared to the traditional distributed turbo coding, while simultaneously providing a gain of 0.7dB in bit error rate. This latter gain rises to approximately 2.5dB when a fast fading environment is considered. Furthermore, an outage probability analysis is conducted, which corroborates the simulated performance results.Copyright © 2014 John Wiley & Sons, Ltd.\",\n \"Title: Factor graph based receiver design for PCC-coded BPSK transmissions over a frequency-selective fading channel\\nYear: 2007\\n\\nAbstract: This paper presents an iterative receiver to detect and decode parallel concatenated convolutional (PCC) coded BPSK transmissions over a frequency-selective Rayleigh fading channel. The scheme generalises work by Valenti and Woerner to frequency- selective channels. A detailed derivation of the receiver from factor graph theory is presented. For the purposes of channel estimation, a Wiener filter based estimator is derived, and the interaction between the channel estimation procedure and the message-passing algorithm is illustrated. In particular it is shown that, in contrast to Valenti and Woerner's scheme, the pilot symbols appear as variables in the factor graph, leading to the insertion and removal of 'pilot symbol LLRs' in the receiver. Finally, the BER performance of the system is demonstrated through computer simulations. Copyright (C) 2007 John Wiley & Sons, Ltd.\",\n \"Title: On a class of doubly-generalized LDPC codes with single parity-check variable nodes\\nYear: 2009\\n\\nAbstract: A class of doubly-generalized low-density parity-check (D-GLDPC) codes, where single parity-check (SPC) codes are used as variable nodes (VNs), is investigated. An expression for the growth rate of the weight distribution of any D-GLDPC ensem ble with a uniform check node (CN) set is presented at first, together with an analytical technique for its efficient evaluation. These tools are then used for detailed analysis of a case study, namely, a rate-1/2 D-GLDPC ensemble where all the CNs are (7,4) Hamming codes and all the VNs are length-7 SPC codes. It is illustrated how the VN representations can heavily affect the code properties and how different VN representations can be combined within the same graph to enhance some of the code parameters. The analysis is conducted over the binary erasure channel. Interesting features of the new codes include the capability of achieving a good compromise between waterfall and error floor performance while preserving graphical regularity, and values of threshold outperforming LDPC counterparts.\",\n \"Title: A Unified Framework for Linear-Programming Based Communication Receivers\\nYear: 2011\\n\\nAbstract: It is shown that a large class of communication systems which admit a sum-product algorithm (SPA) based receiver also admit a corresponding linear-programming (LP) based receiver. The two receivers have a relationship defined by the local structure of the underlying graphical model, and are inhibited by the same phenomenon, which we call pseudoconfigurations. This concept is a generalization of th...\",\n \"Title: Stability of Iterative Decoding of Multi-Edge Type Doubly-Generalized LDPC Codes Over the BEC\\nYear: 2011\\n\\nAbstract: Using the EXIT chart approach, a necessary and sufficient condition is developed for the local stability of iterative decoding of multi-edge type (MET) doubly-generalized low-density parity-check (D-GLDPC) code ensembles. In such code ensembles, the use of arbitrary linear block codes as component codes is combined with the further design of local Tanner graph connectivity through the use of multiple edge types. The stability condition for these code ensembles is shown to be succinctly described in terms of the value of the spectral radius of an appropriately defined polynomial matrix.\",\n \"Title: Multiple Cell Upset Correction in Memories Using Difference Set Codes.\\nYear: 2012\\n\\nAbstract: Error Correction Codes (ECCs) are commonly used to protect memories from soft errors. As technology scales, Multiple Cell Upsets (MCUs) become more common and affect a larger number of cells. An option to protect memories against MCUs is to use advanced ECCs that can correct more than one error per word. In this area, the use of one step majority logic decodable codes has recently been proposed fo...\",\n \"Title: Exploration of AWGNC and BSC Pseudocodeword Redundancy\\nYear: 2010\\n\\nAbstract: The AWGNC, BSC, and max-fractional pseudocodeword redundancy of a code is\\ndefined as the smallest number of rows in a parity-check matrix such that the\\ncorresponding minimum pseudoweight is equal to the minimum Hamming distance of\\nthe code. This paper provides new results on the AWGNC, BSC, and max-fractional\\npseudocodeword redundancies of codes. The pseudocodeword redundancies for all\\ncodes of small length (at most 9) are computed. Also, comprehensive results are\\nprovided on the cases of cyclic codes of length at most 250 for which the\\neigenvalue bound of Vontobel and Koetter is sharp.\",\n \"Title: Spectral Shape of Doubly-Generalized LDPC Codes: Efficient and Exact Evaluation\\nYear: 2012\\n\\nAbstract: This paper analyzes the asymptotic exponent of the weight spectrum for irregular doubly-generalized LDPC (D-GLDPC) codes. In the process, an efficient numerical technique for its evaluation is presented, involving the solution of a 4 $\\\\\\\\,\\\\\\\\,\\\\\\\\times$ 4 system of polynomial equations. The expression is consistent with previous results, including the case where the normalized weight or stopping set size tends to zero. The spectral shape is shown to admit a particularly simple form in the special case where all variable nodes are repetition codes of the same degree, a case which includes Tanner codes; for this case it is also shown how certain symmetry properties of the local weight distribution at the CNs induce a symmetry in the overall weight spectral shape function. Finally, using these new results, weight and stopping set size spectral shapes are evaluated for some example generalized and doubly-generalized LDPC code ensembles.\",\n \"Title: On Joint Cryptographic Verification and Channel Decoding via the Maximum Likelihood Criterion.\\nYear: 2012\\n\\nAbstract: The scenario is considered where a message, together with its message authentication code (MAC), is transmitted over a noisy channel. It is assumed that a forward error correcting channel code is used to reduce the error rate, but no repeat mechanism (ARQ) is used to correct the remaining errors. In such systems, uncorrected errors usually cause rejection of messages with an incorrect MAC. This pa...\",\n \"Title: Lower Bounds on the Minimum Pseudodistance for Linear Codes with $q$-ary PSK Modulation over AWGN\\nYear: 2008\\n\\nAbstract: We present lower bounds on the minimum pseu- docodeword effective Euclidean distance (or minimum \\\"pseu- dodistance\\\") for coded modulation systems using linear codes with q-ary phase-shift keying (PSK) modulation over the ad- ditive white Gaussian noise (AWGN) channel. These bounds apply to both binary and nonbinary coded modulation systems which use direct modulation mapping of coded symbols. The minimum pseudodistance may serve as a first-order measure of error-correcting performance for both linear-programming and message-passing based receivers. In the case of a linear- programming based receiver, the minimum pseudodistance may be used to form an exact bound on the codeword error rate of the system.\",\n \"Title: Low Complexity Linear Programming Decoding of Nonbinary Linear Codes\\nYear: 2010\\n\\nAbstract: Linear Programming (LP) decoding of Low-Density Parity-Check (LDPC) codes has\\nattracted much attention in the research community in the past few years. The\\naim of LP decoding is to develop an algorithm which has error-correcting\\nperformance similar to that of the Sum-Product (SP) decoding algorithm, while\\nat the same time it should be amenable to mathematical analysis. The LP\\ndecoding algorithm has also been extended to nonbinary linear codes by Flanagan\\net al. However, the most important problem with LP decoding for both binary and\\nnonbinary linear codes is that the complexity of standard LP solvers such as\\nthe simplex algorithm remain prohibitively large for codes of moderate to large\\nblock length. To address this problem, Vontobel et al. proposed a low\\ncomplexity LP decoding algorithm for binary linear codes which has complexity\\nlinear in the block length. In this paper, we extend the latter work and\\npropose a low-complexity LP decoding algorithm for nonbinary linear codes. We\\nuse the LP formulation proposed by Flanagan et al. as a basis and derive a pair\\nof primal-dual LP formulations. The dual LP is then used to develop the\\nlow-complexity LP decoding algorithm for nonbinary linear codes. In contrast to\\nthe binary low-complexity LP decoding algorithm, our proposed algorithm is not\\ndirectly related to the nonbinary SP algorithm. Nevertheless, the complexity of\\nthe proposed algorithm is linear in the block length and is limited mainly by\\nthe maximum check node degree. As a proof of concept, we also present a\\nsimulation result for a $[80,48]$ LDPC code defined over $\\\\mathbb{Z}_4$ using\\nquaternary phase-shift keying over the AWGN channel, and we show that the\\nerror-correcting performance of the proposed LP decoding algorithm is similar\\nto that of the standard LP decoding using the simplex solver.\",\n \"Title: Spectral graph analysis of quasi-cyclic codes\\nYear: 2009\\n\\nAbstract: In this paper we analyze the bound on the additive white Gaussian noise channel (AWGNC) pseudo-weight of a (c, d)-regular linear block code based on the two largest values ¿1 > ¿2 of the eigenvalues of HTH: wp min > (H) ¿ n = 2c-¿2/¿1-¿2. In particular, we analyze (c, d)-regular quasi-cyclic (QC) codes of length rL described by J à L block parity-check matrices with circulant block entries of size r à r. We proceed by showing how the problem of computing the eigenvalues of the rL à rL matrix HTH can be reduced to the problem of computing eigenvalues for r matrices of size L à L. We also give a necessary condition for the bound to be attained for a circulant matrix H and show a few classes of cyclic codes satisfying this criterion.\",\n \"Title: Joint Channel and Network Coding for Cooperative Diversity in a Shared-Relay Environment\\nYear: 2010\\n\\nAbstract: In this paper we propose a cooperative diversity scheme for the communication model of two sources sharing a single relay. The scheme uses algebraic code superposition relaying in the multiple access fading channel to create spatial diversity under the constraint of limited communications resources. We also describe in detail a novel computationally efficient message passing algorithm at the destination's decoder which extracts the substantial spatial diversity contained in the code superposition and signal superposition. The decoder is based on a sliding window structure where certain a posteriori LLRs are retained to form a priori LLRs for the next decoding. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.\",\n \"Title: Design of LDPC Code Ensembles with Fast Convergence Properties.\\nYear: 2014\\n\\nAbstract: The design of low-density parity-check (LDPC) code ensembles optimized for a finite number of decoder iterations is investigated. Our approach employs EXIT chart analysis and differential evolution to design such ensembles for the binary erasure channel and additive white Gaussian noise channel. The error rates of codes optimized for various numbers of decoder iterations are compared and it is seen that in the cases considered, the best performance for a given number of decoder iterations is achieved by codes which are optimized for this particular number. The design of generalized LDPC (GLDPC) codes is also considered, showing that these structures can offer better performance than LDPC codes for low-iteration-number designs. Finally, it is illustrated that LDPC codes which are optimized for a small number of iterations exhibit significant deviations in terms of degree distribution and weight enumerators with respect to LDPC codes returned by more conventional design tools.\",\n \"Title: Codeword-independent performance of nonbinary linear codes under linear-programming and sum-product decoding\\nYear: 2008\\n\\nAbstract: A coded modulation system is considered in which nonbinary coded symbols are mapped directly to nonbinary modulation signals. It is proved that if the modulator-channel combination satisfies a particular symmetry condition, the codeword error rate performance is independent of the transmitted codeword. It is shown that this result holds for both linear-programming decoders and sum-product decoders. In particular, this provides a natural modulation mapping for nonbinary codes mapped to PSK constellations for transmission over memoryless channels such as AWGN channels or flat fading channels with AWGN.\",\n \"Title: Linear-programming receivers\\nYear: 2008\\n\\nAbstract: It is shown that any communication system which admits a sum-product (SP) receiver also admits a corresponding linear-programming (LP) receiver. The two receivers have a relationship defined by the local structure of the underlying graphical model, and are inhibited by the same phenomenon, which we call pseudoconfigurations. This concept is a generalization of the concept of pseudocodewords for linear codes. It is proved that the LP receiver has the dasiaoptimum certificatepsila property, and that the receiver output is the lowest cost pseudoconfiguration. Equivalence of graph-cover pseudoconfigurations and linear-programming pseudoconfigurations is also proved. While the LP receiver is generally more complex than the corresponding SP receiver, the LP receiver and its associated pseudoconfiguration structure provide an analytic tool for the analysis of SP receivers. As an example application, we show how the LP design technique may be applied to the problem of joint equalization and decoding.\",\n \"Title: Error Detection in Majority Logic Decoding of Euclidean Geometry Low Density Parity Check (EG-LDPC) Codes\\nYear: 2013\\n\\nAbstract: In a recent paper, a method was proposed to accelerate the majority logic decoding of difference set low density parity check codes. This is useful as majority logic decoding can be implemented serially with simple hardware but requires a large decoding time. For memory applications, this increases the memory access time. The method detects whether a word has errors in the first iterations of majority logic decoding, and when there are no errors the decoding ends without completing the rest of the iterations. Since most words in a memory will be error-free, the average decoding time is greatly reduced. In this brief, we study the application of a similar technique to a class of Euclidean geometry low density parity check (EG-LDPC) codes that are one step majority logic decodable. The results obtained show that the method is also effective for EG-LDPC codes. Extensive simulation results are given to accurately estimate the probability of error detection for different code sizes and numbers of errors.\",\n \"Title: On the Pseudocodeword Redundancy of Binary Linear Codes\\nYear: 2012\\n\\nAbstract: For a binary linear code, the pseudocodeword redundancy with respect to the additive white Gaussian noise channel, the binary symmetric channel, or the max-fractional weight is defined to be the smallest number of rows in a parity-check matrix such that the corresponding minimum pseudoweight is equal to the minimum Hamming distance of the code. It is shown that most codes do not have a finite pseudocodeword redundancy. Also, upper bounds on the pseudocodeword redundancy for some families of codes, including codes based on designs, are provided. The pseudocodeword redundancies for all codes of small length (at most 9) are computed. Furthermore, comprehensive results are provided on the cases of cyclic codes of length at most 250 for which the eigenvalue bound of Vontobel and Koetter is sharp.\",\n \"Title: Serial Symbol-Reliability Based Algorithm for Decoding Non-Binary LDPC Codes\\nYear: 2012\\n\\nAbstract: A symbol-reliability based decoding algorithm with serial schedule for non-binary low-density parity-check (LDPC) codes is presented. Performance results, together with implementation complexity analysis, are provided for different sample codes. The proposed algorithm achieves a similar gain to the min- max algorithm for codes with column weight dv ≥ 6, with lower complexity than previous symbol-reliability based algorithms.\",\n \"Title: Exposing pseudoweight layers in regular LDPC code ensembles\\nYear: 2009\\n\\nAbstract: A solution is presented for the asymptotic growth rate of the AWGN-pseudoweight distribution of regular low-density parity-check (LDPC) code ensembles for a selected graph cover degree M ¿1. The evaluation of the growth rate requires solution of a system of 2M +1 nonlinear equations in 2M +1 unknowns. Simulation results for the pseudoweight distribution of two regular LDPC code ensembles are presented for graph covers of low degree.\",\n \"Title: On the pseudocodeword redundancy\\nYear: 2010\\n\\nAbstract: We define the AWGNC, BSC, and max-fractional pseudocodeword redundancy of a\\ncode as the smallest number of rows in a parity-check matrix such that the\\ncorresponding minimum pseudoweight is equal to the minimum Hamming distance. We\\nshow that most codes do not have a finite pseudocodeword redundancy. We also\\nprovide bounds on the pseudocodeword redundancy for some families of codes,\\nincluding codes based on designs.\",\n \"Title: Low-Complexity LP Decoding of Nonbinary Linear Codes\\nYear: 2012\\n\\nAbstract: Linear Programming (LP) decoding of Low-Density Parity-Check (LDPC) codes has attracted much attention in the research community in the past few years. LP decoding has been derived for binary and nonbinary linear codes. However, the most important problem with LP decoding for both binary and nonbinary linear codes is that the complexity of standard LP solvers such as the simplex algorithm remains prohibitively large for codes of moderate to large block length. To address this problem, two low-complexity LP (LCLP) decoding algorithms for binary linear codes have been proposed by Vontobel and Koetter, henceforth called the basic LCLP decoding algorithm and the subgradient LCLP decoding algorithm. In this paper, we generalize these LCLP decoding algorithms to nonbinary linear codes. The computational complexity per iteration of the proposed nonbinary LCLP decoding algorithms scales linearly with the block length of the code. A modified BCJR algorithm for efficient check-node calculations in the nonbinary basic LCLP decoding algorithm is also proposed, which has complexity linear in the check node degree. Several simulation results are presented for nonbinary LDPC codes defined over Z 4 , GF(4), and GF(8) using quaternary phase-shift keying and 8-phase-shift keying, respectively, over the AWGN channel. It is shown that for some group-structured LDPC codes, the error-correcting performance of the nonbinary LCLP decoding algorithms is similar to or better than that of the min-sum decoding algorithm.\",\n \"Title: A Soft Decode-Compress-Forward Relaying Scheme for Cooperative Wireless Networks\\nYear: 2013\\n\\nAbstract: This paper proposes a new technique for soft information relaying, which is based on a soft decode–compress–forward relay protocol. The proposed system provides a means of using distributed low-density parity-check (LDPC) coding in conjunction with higher order modulation, such as pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM), which is effective even under poor source–relay link conditions. Ordinarily, such schemes suffer from error propagation to the destination caused by incorrect decoding at the relay when the signal-to-noise ratio (SNR) on the source–relay link is low; however, our system avoids this problem by generating soft versions of the additional (parity-bearing) PAM symbols for transmission from the relay. The proposed technique of soft compression does not suffer from parity log-likelihood ratios (LLRs) converging to zero, as do many soft re-encoding techniques for turbo and LDPC codes. In the case of Gray-coded PAM/QAM signaling, we also propose a method of performing exact expectation-based soft modulation with low computational complexity. Furthermore, we propose a new model, which we refer to as the soft scalar model, for the overall source-to-destination channel encountered by the constellation symbols, and this model is used at the destination to compute LLRs for joint decoding of the distributed LDPC code. Simulation results demonstrate that the proposed scheme can provide good coding gain, diversity gain, and spectral efficiency under poor source–relay SNR conditions.\",\n \"Title: LDPC coding with soft information relaying in cooperative wireless networks\\nYear: 2013\\n\\nAbstract: This paper investigates soft information relaying (SIR) for low-density parity-check (LDPC) coded transmission in wireless networks. We introduce a new scheme for soft parity symbol generation at the relay, which features two key strategies: a two-step soft parity generation process, and a prescaling technique. The two-step soft parity generation procedure is designed to allow efficient relay processing, while yielding an overall (i.e., destination) parity-check matrix structure with desirable properties. The pre-scaling method prevents the amplitudes of generated soft symbols successively converging to zero, as happens with some existing soft forwarding methods. Finally, we propose an appropriate LLR former at the destination which is tailored to the proposed soft parity generation technique. Simulation results demonstrate that the proposed relay protocol yields an improved BER performance compared to competitive schemes proposed in the literature.\",\n \"Title: Low-Density Lattice Coded Relaying with Joint Iterative Decoding\\nYear: 2015\\n\\nAbstract: Low-density lattice codes (LDLCs) are known for their high decoding efficiency and near-capacity performance on point-to-point Gaussian channels. In this paper, we present a distributed LDLC-based cooperative relaying scheme for the multiple-access relay channel (MARC). The relay node decodes LDLC coded packets from two sources and forwards a networkcoded combination to the destination. At the destination, a joint iterative decoding structure is designed to exploit the diversity gain as well as coding gain. For the LDLC-based network coding operation at the relay, we consider two alternative methods which offer a tradeoff between implementation complexity and performance, called superposition LDLC (S-LDLC) and moduloaddition LDLC (MA-LDLC). Soft symbol relaying is considered as an alternative to hard decision relaying which is capable of reducing the effect of error propagation at the relay. Simulation results show that the proposed scheme can provide greater diversity gain and up to 6.2 dB coding gain when compared with non-cooperative LDLC coding and uncoded network-coded transmission. The proposed scheme also achieves 2.5 dB gain over network-turbo-coded cooperation, for the same code rate and overall transmitted power. Also, soft symbol relaying is shown to provide approximately 2 dB gain over hard decision relaying when the source-relay link suffers from deep fading.\",\n \"Title: Distributed Low-Density Lattice Codes\\nYear: 2016\\n\\nAbstract: This letter presents a novel distributed LDLC (D-LDLC) relaying scheme for the classical relay channel. The relay node decodes LDLC packets from the source and forwards an additional parity message to the destination. The destination then performs joint decoding in order to exploit the available coding gain as well as diversity gain. First, assuming AWGN links, density evolution is used to optimize the noise threshold of the overall parity-check matrix, and this method is shown to produce good finite-length D-LDLC designs. Then, we provide results for the optimized D-LDLCs under Rayleigh fading channel conditions. Joint decoding based on D-LDLC is shown to provide approximately 3 dB gain over distributed 4-PAM turbo codes under the same conditions (data rate and overall transmission power).\",\n \"Title: Simultaneous Uplink/Downlink Transmission Using Full-Duplex Single-RF MIMO.\\nYear: 2016\\n\\nAbstract: In this letter, we introduce a full-duplex protocol for simultaneous transmission between the uplink and the downlink of cellular networks. The protocol takes advantage of the inactive antenna(s) in multiple-input-multiple-output (MIMO) systems with a single active radio frequency (RF) front-end. More precisely, for the downlink transmissions, we make use of spatial modulation (SM), and for the uplink, we make use of the coordinate-interleaved orthogonal design (CIOD)-based space-time block code (STBC). We provide accurate mathematical expressions for evaluating the error-performances and the achievable diversity order at the base station (BS) and at the mobile terminal (MT) in the presence of self-interference. Our results demonstrate clearly the potential of SM and CIOD for full-duplex operation.\",\n \"Title: LDPC coded soft forwarding with network coding for the two-way relay channel\\nYear: 2014\\n\\nAbstract: This paper investigates a low-density parity-check (LDPC) coded soft-decode-and-forward (SDF) relaying protocol for a two way relay channel (TWRC). In this SDF protocol, the relay evaluates the reliabilities, expressed as log-likelihood ratios (LLRs), of the received signals from the two sources. The relay then forwards a network-coded combination of the parity symbols of both sources, but in the “soft” domain to avoid error propagation from the relay. We introduce a model for the effective noise experienced by the soft network coded symbols, constituting the new parameters of soft scalar and soft error; this model is then used to compute the log-likelihood ratios (LLRs) at the destination. To facilitate this latter computation, we have derived an analytical expression for soft error variance, as well as a simplified expression based on a common assumption on the statistical behavior of the LLRs. This enables low-complexity computation and tracking of the soft error variance on-the-fly. The proposed system outperforms standard competing schemes reported in the literature in terms of error rate performance over Rayleigh fading links.\",\n \"Title: A multilevel soft quantize-and-forward scheme for multiple access relay systems\\nYear: 2014\\n\\nAbstract: This paper proposes the novel technique of multilevel threshold based soft quantization (MLT-SQ) for a multiple access relay system (MARS). The scheme is suitable for systems using binary phase-shift keying (BPSK) and network coding at the relay. In the proposed MLT-SQ protocol, the relay evaluates the reliabilities, expressed as log-likelihood ratios (LLRs), of the received signals from the two sources. It then computes the LLRs of the network-coded packet and quantizes these using a set of optimized multilevel thresholds, forwarding the resulting “quantized soft symbols” to the destination. We provide the derivation for the bit error rate (BER) at the destination, based on which we optimize the multilevel thresholds to minimize the BER. Compared to competing schemes, the performance of our system is superior in terms of BER when the same amount of channel state information (CSI) is exploited.\",\n \"Title: An Efficient Joint Channel-Network Decoder for Multiuser Diversity Network Codes With LDPC Coding.\\nYear: 2016\\n\\nAbstract: Diversity network codes (DNCs) were recently proposed for multiuser cooperative networks, where nonbinary network codes are superimposed over channel codes to yield high diversity gains. In this letter, we present a joint iterative channel-network decoder for use at the base station in a system employing a DNC. The scheme is based on hybrid soft/hard message passing between constituent low-complexity low-density parity-check (LDPC) decoders. It is shown that the formation of the extrinsic log-likelihood ratios to be passed between the LDPC decoders has a low-complexity implementation involving a set of permutation operations together with the well-known Jacobian logarithm. The proposed joint channel-network decoder has a significantly reduced complexity compared with the decoding structure originally presented for maximum-diversity-achieving DNCs, and achieves significant coding gain as well as full diversity gain.\",\n \"Title: Efficient and Exact Evaluation of the Weight Spectral Shape and Typical Minimum Distance of Protograph LDPC Codes.\\nYear: 2016\\n\\nAbstract: In this letter, an analytical method for evaluating the weight spectral shape of a nonbinary protograph low-density parity-check code ensemble is provided. This method, which requires simultaneous solution of a system of equations, is more efficient to implement than the existing methods that require the numerical solution of a high-dimensional maximization problem. It is also shown that by adding a single equation to the proposed system, it is possible to directly solve for the typical minimum distance of the ensemble. This makes the proposed method particularly useful for the ensemble design scenario where a constraint is placed on the typical minimum distance. The proposed method is verified through the evaluation of the weight spectral shape of some example protograph ensembles.\",\n \"Title: A Virtual Full Duplex Distributed Spatial Modulation Technique For Relay Networks\\nYear: 2016\\n\\nAbstract: Spatial modulation, a multiple-input multipleoutput (MIMO) technology which uses the antenna index to transmit part of the incoming data, is an attractive way to reduce the energy cost and transceiver complexity in future wireless networks. In particular, the recently proposed technique of distributed spatial modulation (DSM) for relay networks can lead to better spectral efficiency, as it allows the relays to transmit their own data while simultaneously relaying the data of the source. A new distributed spatial modulation protocol is introduced in this paper which achieves virtual full duplex (VFD) communication. In this protocol, the source and relays transmit their own data in every time slot; thus, the spectral efficiency is significantly improved compared to conventional DSM. Simulation results indicate that at high signal-to-noise ratio (SNR), the proposed protocol has similar bit error rate (BER) performance versus SNR-per-bit compared to the standard full duplex relaying protocol of successive relaying; however, in contrast to successive relaying, the relays are simultaneously transmitting their own data, which is received at the destination with an error rate similar to that of the source's data.\",\n \"Title: On Generalized Spatial Modulation For Multiuser Wireless Communications\\nYear: 2017\\n\\nAbstract: The recently proposed multiple-input multiple-output (MIMO) technique of spatial modulation (SM) has attracted a good deal of attention due to its low implementation and computational complexity, and the spectral efficiency and energy efficiency gains it offers over many conventional MIMO schemes. There has been some progress made in applying SM to multiuser scenarios, including a proposed precoding scheme to eliminate the Multiuser Interference (MUI) associated with multiuser environments. A generalized technique for SM has also been proposed that promises further spectral efficiency gains over conventional SM. This paper proposes a precoding scheme to eliminate MUI in a generalized spatial modulation (GSM) scenario, thereby allowing individual users to employ a single-user Maximum Likelihood optimum detector. An interference-aware multiuser detection scheme is developed and the performance of both schemes is compared. The effect of precoder power normalization on the error rate performance is also explored in detail. Precoding is found to facilitate less complex detection and superior error rate performance in the multiuser GSM context.\",\n \"Title: Physical-layer network coded QAM with trellis shaping for the two-way relay channel\\nYear: 2016\\n\\nAbstract: Physical-layer network coding (PNC) allows to improve the throughput on the two-way relay channel (TWRC). PNC systems using higher-order modulation present some challenges regarding how to design the PNC mapping at the relay. With higher-order modulation it is also desirable to use constellation shaping which allows to minimize the average transmitted energy. In this paper, we show how low-complexity trellis shaping can be used to provide constellation shaping both at the user nodes and at the relay node. The proposed technique works specifically for sign bit shaping and M-ary quadrature amplitude modulation (QAM). Simulation results show that the proposed scheme provides a significantly increased performance in terms of the achievable BER, with 5.3dB shaping gain available at a BER of 10\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">-3</sup>\\n in the case of 256-QAM signaling.\",\n \"Title: Non-Binary Ldpc Codes For Orthogonal Modulations: Analysis And Code Design\\nYear: 2017\\n\\nAbstract: In this paper, we present a low-density parity-check coded modulation approach addressing orthogonal modulations with moderate order (between 8 and 32) over the additive white Gaussian noise channel. The proposed design is based on a constrained optimization of a non-binary low-density parity-check ensemble degree distribution, where the iterative decoding threshold is optimized via extrinsic information transfer analysis while restricting the search to degree distributions that target low error floors. For various orthogonal modulation orders, we provide useful approximations to the extrinsic information transfer functions, which enable a fast optimization with respect to the iterative decoding threshold. The approach is validated via codeword error rate Monte Carlo simulations and complemented by an error floor analysis, showing gains up to 0.8 dB at a codeword error rate of 10(-4) with respect to existing designs, down to information block lengths as short as 192 bits.\",\n \"Title: A low-complexity correlation-based time skew estimation technique for time-interleaved SAR ADCs\\nYear: 2017\\n\\nAbstract: This paper presents a technique to estimate the time skew in time-interleaved ADCs. The proposed method estimates all of the time skew parameters jointly based on observations from a bank of correlators. The proposed method works for an arbitrary number of sub-ADCs. For implementation of the correlator bank, we propose the use of Mitchell's logarithmic multiplier and a hardware reuse mechanism, thereby reducing the complexity and power consumption. Also, we explain why blind estimation techniques alone (including the proposed one) are not always sufficient for time skew estimation for certain classes of input signal; for the proposed approach, however, a simple modification to the analogue circuit (suitable for SAR ADCs) is shown to successfully deal with such problems, with only a minor penalty in power and area. The technique is verified by extensive simulations including a spectrally rich input signal in which an MTPR (multi-tone power ratio) improvement from 29dB to 62dB was achieved for a TIADC system having 16 sub-ADCs.\",\n \"Title: Transmit Antenna Selection for Physical-Layer Network Coding Based on Euclidean Distance.\\nYear: 2017\\n\\nAbstract: Physical-layer network coding (PNC) is now well-known as a potential candidate for delay-sensitive and spectrally efficient communication applications, especially in two-way relay channels (TWRCs). In this paper, we present the error performance analysis of a multiple-input single-output (MISO) fixed network coding (FNC) system with two different transmit antenna selection (TAS) schemes. For the first scheme, where the antenna selection is performed based on the strongest channel, we derive a tight closed-form upper bound on the average symbol error rate (SER) with M-ary modulation and show that the system achieves a diversity order of 1 for M > 2. Next, we propose a Euclidean distance (ED) based antenna selection scheme which outperforms the first scheme in terms of error performance and is shown to achieve a diversity order lower bounded by the minimum of the number of antennas at the two users.\",\n \"Title: A Generic Foreground Calibration Algorithm For ADCs with Nonlinear Impairments.\\nYear: 2018\\n\\nAbstract: This paper presents a generic foreground calibration algorithm that estimates and corrects memoryless nonlinear impairments in both single channel and time-interleaved analog-to-digital converters (TIADCs), and which is capable of correcting for amplifier nonlinearity, comparator offsets, and capacitance mismatch for each channel. It operates by generating, and then using, a look-up table which ma...\",\n \"Title: Wireless-Powered Distributed Spatial Modulation With Energy Recycling and Finite-Energy Storage.\\nYear: 2018\\n\\nAbstract: The distributed spatial modulation (DSM) protocol, which allows relays to forward the source's data while simultaneously allowing the relays to transmit their own data, has been proposed by Narayanan et al. In this paper, we introduce two new protocols for enabling the DSM, consisting of single-antenna network nodes, with simultaneous wireless information and power transfer capability: power split...\",\n \"Title: Gibbs Sampling Aided Throughput Improvement for Next-Generation Wi-Fi\\nYear: 2018\\n\\nAbstract: Wireless communications, and in particular wireless local area network (WLAN) technology, has undergone a tremendous evolution in the past decades. After the release of the WLAN standard IEEE 802.11a/b in 1999, Wi-Fi technology soon became pervasive, thanks mainly to its deployment on the unlicensed ISM band. However, high traffic, especially in hotspots and areas with dense deployment of Wi-Fi access points (APs) (e.g., stations, airports, etc.) has caused major issues and a severe degradation of communications quality. The latest WLAN standards (e.g., 802.11ac, 802.11ax) have largely succeeded in improving the link quality and data rate by adopting state-of-the-art PHY layer technologies, e.g., OFDMA, MU-MIMO. However, improvement of the MAC layer in these standards is not noticeable due to restrictions such as hardware limitation and backward compatibility issues for legacy APs. As an effort to improve the MAC layer for the next-generation WLAN standard, in this paper we propose a simple algorithm with low computational complexity for channel selection in Wi-Fi networks. The main idea is to take advantage of the potential of the IEEE 802.11ax MAC to avoid major standard modifications. For this purpose, we employ the channel utilization ratio (CUR), which is measured periodically by each AP based on its channel sensing. Time-averaged CUR values are weighted based on a Gibbs sampling approach and a probability associated to each channel is updated. Finally, a channel is selected based on the aforementioned probabilities in predefined time slots. Simulation results show that the proposed approach can improve the system throughput by up to 5% and transmission delay by up to 20%.\",\n \"Title: Satisfaction Based Channel Allocation Scheme for Self-Organization in Heterogeneous Networks.\\nYear: 2018\\n\\nAbstract: The next-generation wireless networks are expected to become denser and more heterogeneous in order to boost the network capacity. However, densely deployed base stations (BSs) in heterogeneous networks (HetNets) can give rise to interference. On the other hand, a limited number of channels is allocated within the HetNets. Therefore, the efficient assignment of channels among BSs is considered to be an important issue. Furthermore, the density and heterogeneity of the networks motivate self-organizing resource management techniques. In this paper, we address the problem of channel allocation in HetNets, and propose a satisfaction based channel allocation algorithm. The problem is modeled as a game in satisfaction form, in which BSs act as the players with the constraint given by the loads at the BSs. The objective is to meet the data rate requirements of user equipments. In this regard, the BSs aim at seeking a satisfaction solution rather than the optimal one. In order to learn the satisfaction equilibrium, a fully distributed algorithm based on the individual utility is applied. Simulation results show that the proposed approach can increase the average BS's throughput compared to the benchmark algorithms.\",\n \"Title: On the Performance of NOMA-based Cooperative Relaying with Receive Diversity\\nYear: 2019\\n\\nAbstract: Non-orthogonal multiple access (NOMA) is widely recognized as a potential multiple access (MA) technology for efficient spectrum utilization in the fifth-generation (5G) wireless standard. In this paper, we present the achievable sum rate analysis of a cooperative relaying system (CRS) using NOMA with two different receive diversity schemes - selection combining (SC), where the antenna with highest instantaneous signal-to-noise ratio (SNR) is selected, and maximal-ratio combining (MRC). We also present the outage probability and diversity analysis for the CRS-NOMA system. Analytical results confirm that the CRS-NOMA system outperforms the CRS with conventional orthogonal multiple access (OMA) by achieving higher spectral efficiency at high transmit SNR and achieves a full diversity order.\",\n \"Title: On the Performance of Spatial Modulation MIMO for Full-Duplex Relay Networks.\\nYear: 2017\\n\\nAbstract: In this paper, we investigate, for the first time, the performance of a full-duplex (FD) relaying protocol, where a single-RF spatial modulation (SM) multiple-input multiple-output (MIMO) system is employed at the relay node. We refer to this protocol as SM-aided FD relaying (SM-FDR). At the destination, a demodulator that takes advantage of the direct connectivity between the source and destinati...\",\n \"Title: Blind SAR ADC capacitor mismatch calibration\\nYear: 2017\\n\\nAbstract: This paper presents an all-digital background blind calibration technique for the capacitor mismatch problem in SAR ADCs. It utilizes the redundancy offered using a sub-radix-2 DAC architecture to blindly estimate the mismatch and the assigned weight for each comparator decision. The weights are estimated by building partial histogram windows for the comparator decision vectors. To remove the dependency on the input signal's probability density function, the histogram windows are normalized with respect to their peaks. Matlab simulation results show that an ENOB within 0.12bit of the optimal is attained using the proposed algorithm.\",\n \"Title: User-Antenna Selection for Physical-Layer Network Coding based on Euclidean Distance.\\nYear: 2019\\n\\nAbstract: In this paper, we present the error performance analysis of a multiple-input multiple-output (MIMO) physical-layer network coding (PNC) system with two different user-antenna selection (AS) schemes in asymmetric channel conditions. For the first antenna selection scheme (AS1), where the user antenna is selected in order to maximize the overall channel gain between the user and the relay, we give a...\",\n \"Title: A High-Precision Time Skew Estimation and Correction Technique for Time-Interleaved ADCs\\nYear: 2019\\n\\nAbstract: This paper presents an all-digital background calibration technique for the time skew mismatch in time-interleaved ADCs (TIADCs). The technique jointly estimates all of the time skew values by processing the outputs of a bank of correlators. A low-complexity sampling sequence intervention technique, suitable for successive approximation register (SAR) ADC architectures, is proposed to overcome the limitations associated with blind estimation. A two-stage digital correction mechanism based on the Taylor series is proposed to satisfy the target high-precision correction. A quantitative study is performed regarding the requirements imposed on the digital correction circuit in order to satisfy the target performance and yield, and a corresponding filter design method is proposed, which is tailored to meet these requirements. Mitchell’s logarithmic multiplier is adopted for the implementation of the principal multipliers in both the estimation and correction mechanisms, leading to a 25% area and power reduction in the estimation circuit. The proposed calibration is synthesized using a TSMC 28-nm HPL process targeting a 2.4-GHz sampling frequency for an eight-sub-ADC system. The calibration block occupies 0.03 mm\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">2</sup>\\n and consumes 11 mW. The algorithm maintains the SNDR above 65 dB for a sinusoidal input within the target bandwidth.\",\n \"Title: On the Secrecy Rate of Downlink NOMA in Underlay Spectrum Sharing with Imperfect CSI: Invited Paper\\nYear: 2021\\n\\nAbstract: In this paper, we present the ergodic sum secrecy rate (ESSR) analysis of an underlay spectrum sharing nonorthogonal multiple access (NOMA) system. We consider the scenario where the power transmitted by the secondary transmitter (ST) is constrained by the peak tolerable interference at multiple primary receivers (PRs) as well as the maximum transmit power of the ST. The effect of channel estimati...\",\n \"Title: On Characterizing The Capacity Region Of Massive Mimo Systems With Joint Power Constraints\\nYear: 2021\\n\\nAbstract: In this paper we consider the problem of computing the capacity of multi-user Gaussian MIMO systems under multiple linear transmit covariance constraints (LTCCs). These LTCCs are general enough to include many transmit power constraints such as sum power constraint (SPC) or per-antenna power constraint (PAPC) as special cases. For the considered MIMO systems with multiple LTCCs, existing solutions are based on subgradient or gradient descent methods, which are known to have slow convergence in general and are therefore not applicable to massive MIMO systems. In contrast, we propose a low-complexity semi-closed-form approach to computing the MIMO capacity for the system of interest. To this end, the considered problem in the broadcast channel is transformed into an equivalent minimax problem in the multiple access channel. The special structure of the minimax problem allows us to derive water-filling-like algorithms based on a novel combination of alternating optimization and concave-convex procedure. For the important case of joint SPC and PAPC, we also propose analytical expressions to find the optimal covariance matrix. Extensive analytical and numerical results are provided to demonstrate the effectiveness of our approach under various massive MIMO system settings.\",\n \"Title: On the Effective Rate of NOMA in Underlay Spectrum Sharing\\nYear: 2021\\n\\nAbstract: In this paper, we present the delay-constrained performance analysis of a multi-antenna-assisted multiuser non-orthogonal multiple access (NOMA) based spectrum sharing system over Rayleigh fading channels. We derive analytical expressions for the sum effective rate (ER) for the downlink NOMA system under a peak interference constraint. In particular, we show the effect of the availability of diffe...\",\n \"Title: On the Achievable Sum-rate of the RIS-aided MIMO Broadcast Channel : Invited Paper\\nYear: 2021\\n\\nAbstract: Reconfigurable intelligent surfaces (RISs) represent a new technology that can shape the radio wave propagation and thus offers a great variety of possible performance and implementation gains. Motivated by this, we investigate the achievable sum-rate optimization in a broadcast channel (BC) that is equipped with an RIS. We exploit the well-known duality between the Gaussian multiple-input multipl...\",\n \"Title: RIS-Assisted Receive Quadrature Space-Shift Keying: A New Paradigm and Performance Analysis\\nYear: 2022\\n\\nAbstract: Reconfigurable intelligent surfaces (RISs) represent a promising candidate for sixth-generation (6G) wireless networks, as the RIS technology provides a new solution to control the propagation channel in order to improve the efficiency of a wireless link through enhancing the received signal power. In this paper, we propose RIS-assisted receive quadrature space shift keying (RIS-RQSSK), which enhances the spectral efficiency of an RIS-based index modulation (IM) system by using the real and imaginary dimensions independently for the purpose of IM. Therefore, the error rate performance of the system is improved as all RIS elements reflect the incident transmit signal toward both selected receive antennas. At the receiver, a low-complexity but effective greedy detector (GD) can be employed which determines the maximum energy per dimension at the receive antennas. A max-min optimization problem is defined to maximize the received signal-to-noise ratio (SNR) components at both selected receive antennas; an analytical solution is provided based on Lagrange duality. In particular, the multi-variable optimization problem is shown to reduce to the solution of a single-variable equation, which results in a very simple design procedure. In addition, we investigate the average bit error probability (ABEP) of the proposed RIS-RQSSK system and derive a closed-form approximate upper bound on the ABEP. We also provide extensive numerical simulations to validate our derivations. Numerical results show that the proposed RIS-RQSSK scheme substantially outperforms recent prominent benchmark schemes. This enhancement considerably increases with an increasing number of receive antennas.\",\n \"Title: Low-Complexity Joint CFO and Channel Estimation for RIS-Aided OFDM Systems\\nYear: 2022\\n\\nAbstract: Accurate channel estimation is essential for achieving the performance gains offered by reconfigurable intelligent surface (RIS)-aided wireless communications. A variety of channel estimation methods have been proposed for such systems; however, none of the existing methods takes into account the effect of synchronization errors such as carrier frequency offset (CFO). In general, CFO can significa...\",\n \"Title: Transceiver Design and Power Control for Full-Duplex Ultra-Reliable Low-Latency Communication Systems\\nYear: 2022\\n\\nAbstract: Ultra-reliable low-latency communication (URLLC) is one of the most important components in the fifth generation (5G) cellular networks for realizing mission-critical applications. In this paper, we jointly optimize the transceiver design and decoding error probability (DEP) of a full-duplex (FD) URLLC system, where the base station (BS) operates in FD mode, while the uplink (UL) and downlink (DL) users work in half-duplex (HD) mode. Accordingly, an optimization problem is formulated to maximize the achievable total (UL plus DL) rate for an FD URLLC system under finite blocklength, subject to the end-to-end (E2E) reliability constraint from the UL user to each DL user and the total transmission power constraint at the UL user and at the BS. We analyze the problem structure and convexify the problem by approximating the channel dispersion in scenarios of high and mid-to-high signal-to-interference plus noise ratio (SINR) regimes, respectively. Next, efficient iterative algorithms are proposed to find the near-optimal power allocation for the UL user and transceiver weights for the BS. Furthermore, closed-form expressions of the transceiver weights are derived, and the convergence of the proposed algorithms is proved. Simulation examples demonstrate the impact of the code blocklength, number of DL users, transmitter/receiver distortion and DEP threshold on the system performance.\",\n \"Title: On the MIMO Capacity With Joint Sum and Per-Antenna Power Constraints: A New Efficient Numerical Method\\nYear: 2022\\n\\nAbstract: We propose a semi-closed-form solution to the problem of computing the capacity and optimal signaling for a Gaussian MIMO channel under a joint sum power constraint (SPC) and per-antenna power constraint (PAPC). Existing efficient solutions to this fundamental problem are only applicable to some special cases: multiple-input single-output (MISO) systems, or full column rank MIMO channels with sufficiently high transmit power, or full-rank optimal signaling. For the general case, we present an efficient numerical method to solve the considered problem which does not make any assumptions on the rank of the channel matrix or the maximum transmit power. To achieve this, the considered problem is transformed into an equivalent minimax problem. We then exploit the special structure of the minimax problem to derive a closed-form solution based on a concave-convex procedure (CCP)-like algorithm. Extensive simulation results show that our proposed algorithm outperforms the existing solutions in terms of complexity and generality.\",\n \"Title: Context-Based Semantic Communication via Dynamic Programming\\nYear: 2022\\n\\nAbstract: Standard digital communication techniques allow us to set aside the meaning of the messages to concentrate on the transmission of bits efficiently and reliably. However, with the integration of artificial intelligence into communications technology and the merging of communication and computation within devices, increasing evidence suggests that the semantic aspect of communication cannot be set aside. We propose a part-of-speech-based encoding strategy and context-based decoding strategies, in which various deep learning models are presented to learn the semantic and contextual features as background knowledge. With the background knowledge, our strategies can be applied to some non-jointly-designed communication scenarios with uncertainty. We compare the performances of two proposed decoding strategies, the deep learning models of which are different, to provide model-choice design guidelines in accordance with specific communication conditions. Further, we discuss the impact of several parameters on the performance of our strategies, such as the size of the context window and the size of the feature window. Simulation results indicate the effectiveness and the reliability of our strategies in terms of decreasing the number of bits used to transmit messages and increasing the semantic accuracy between transmitted messages and recovered messages.\",\n \"Title: Joint power and blocklength optimization for RIS-aided multiple-access downlink ultra-reliable low-latency communication\\nYear: 2022\\n\\nAbstract: Ultra-reliable low-latency communication (URLLC) has gained significant interest since it deals with short packet transmission adopted to reduce latency; however, this implies that the conventional Shannon capacity formula is not applicable, and the achievable data rate becomes a complex function of the decoding error probability and blocklength. This paper studies URLLC transmission using a time-division multiple access scheme with an arbitrary number of actuators utilising a reconfigurable intelligent surface. The authors optimisze the weighted sum rate of this system subject to reliability, total energy, and latency constraints. For the blocklength allocation in a scenario where each actuator is allocated equal power, a closed-form analytical solution is provided. Also, for the case of joint optimization of the blocklength and power of each actuator, an analytical solution is provided for the case of two actuators, while an iterative sequential quadratic programing method is adopted for the case of an arbitrary number of actuators. The proposed methodology provides a low-complexity, fast solution, which is more efficient than using exhaustive search techniques. The results show that in some cases, optimization of the blocklength provides a near-optimal solution at low complexity, while jointly optimising the blocklength and the power per actuator has an improved performance at the cost of additional complexity.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":60,"string":"60"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":80,"string":"80"}}},{"rowIdx":81,"cells":{"question_id":{"kind":"string","value":"Shikharesh Majumdar"},"question":{"kind":"string","value":"Generate an abstract for the title \"Performance of parallel architectures for CORBA-based systems\" using the following items: 1. High performance\n2. Middleware\n3. Distributed object computing systems\n4. Parallel architectures\n5. Performance improvement"},"answer":{"kind":"string","value":"This research is concerned with achieving high performance on middleware-based inter-operable distributed object computing systems. This paper reports a preliminary investigation of the impact of using parallel architectures that use concurrent server invocations to improve performance. One of these architectures is observed to lead to a substantial performance improvement in comparison to the conventional sequential interaction architecture."},"correct_answer":{"kind":"string","value":"This research is concerned with achieving high performance on middleware-based inter-operable distributed object computing systems. This paper reports a preliminary investigation of the impact of using parallel architectures that use concurrent server invocations to improve performance. One of these architectures is observed to lead to a substantial performance improvement in comparison to the conventional sequential interaction architecture."},"documents":{"kind":"list like","value":["Title: BFilter - A XML Message Filtering and Matching Approach in Publish/Subscribe Systems\nYear: 2010\n\nAbstract: In publish/subscribe systems, XML message filtering performed at application layer is an important operation for XML message multicast. As a specific case of content-based multicast in application layer, XML message multicast depends on the data filtering and matching processes and the forwarding and routing schemes. As the XML data emerges in transition, XML message filtering and matching becomes more and more desirable. BFilter, proposed in this paper, conducts the XML message filtering and matching by leveraging branch points in both the XML document and user query. It evaluates user queries that use backward matching branch points to delay further matching processes until branch points match in the XML document and user query. In this way, XML message filtering can be performed more efficiently as the probability of mismatching is reduced. A number of experiments have been conducted and the results demonstrate that BFilter has better performance than the well-known YFilter for complex queries.","Title: Techniques for Achieving High Performance Web Servers\nYear: 2000\n\nAbstract: With increasing bandwidth available to the client and the number of users growing at an exponential rate the Web server can become a performance bottleneck. This paper considers the parallelization of requests to Web pages each of which is composed of a number of embedded objects. The performances of systems in which the embedded objects are distributed across multiple backend servers are analyzed. Parallelization of Web requests gives rise to a significant improvement in performance. Replication of servers is observed to be beneficial especially when the embedded objects in a Web page are not evenly distributed across servers. Load balancing policies used by the dispatcher of Web page requests are investigated. A simple round robin policy for backend server selection gives a better performance compared to the default random policy used by the Apache server.","Title: Caching techniques for XML message filtering\nYear: 2009\n\nAbstract: An XML publish/subscribe system is based on filtering XML message streams for a large number of subscriptions expressed in XPath. A major issue on an XML-based publish/subscribe system is its performance. As the number of XML documents and XPath-based subscriptions increases in the system, to provide XML filtering efficiently becomes a challenging problem. Hence, there is an urgent need for optimization techniques to meet this challenge. There are many existing approaches on designing efficient XML filtering engine. Most existing research efforts focus on efficient filtering algorithms for achieving a high system performance or supporting more complex XPath syntax. Each proposed scheme has its advantages and limitations. Not much research, however, has considered using caching in the context of XML filtering. In this paper, we propose two caching schemes to be used in conjunction with an XML filtering engine. First, we present a complete message caching algorithm that is a strict caching policy to reduce the computation cost that accrues from multiple filtering of the same messages, by reusing results of previously processed messages. Second, we investigate a structure-based caching method that is an approximate caching policy for messages sharing the same structure. Performance evaluation for synthetic data and real data both show that complete message caching and structure-based caching schemes are able to achieve significantly better filtering performance (up to 80% for both caching schemes for the message streams experimented with).","Title: Performance of resource management algorithms for \"Processable Bulk Data Transfer\" Tasks in Grid Environments\nYear: 2008\n\nAbstract: Processable Bulk Data Transfer (PBDT) tasks are resource intensive concurrent tasks which involve transfer of a very large amount of data that has to be processed in some way before it can be used at a remote set of destination nodes called the sink nodes. A distributed computing environment, such as the Grid is a popular way to perform these tasks. Focusing on the execution of PBDT tasks in a Grid computing environment, this paper presents an efficient resource allocation mechanism. Due to the resource thirsty nature of these tasks, an efficient resource allocation is essential to perform these tasks while achieving satisfactory performance. The time-complexity of the resource allocation algorithm rises sharply as the available number of resources in the given Grid computing environment is increased making efficient resource allocation a challenge. To meet this challenge, this paper investigates the use of approximate algorithms for the resource allocation. The benefits obtained by using the reduced complexity of the algorithm are weighed against the increased costs incurred during the task execution (due to the inaccuracies in resource allocation introduced by the approximations). This paper describes a number of approximations and discusses under which circumstances such approximations are to be used. The techniques presented in this research can be extended to non-PBDT tasks and other distributed computing environments.","Title: Measurement and analysis of locality phases in file referencing behaviour\nYear: 1986\n\nAbstract: Recent research has demonstrated the existence of locality in short-term file referencing behaviour. A detailed study of the dynamic characteristics of file referencing is presented in this paper. The concept of Bounded Locality Intervals from the field of program behaviour has been used to model the locality phases of file referencing behaviour. The model is found to be powerful both from a descriptive point of view and from the perspective of understanding the performance implications of locality properties of file referencing behaviour on file system management.","Title: Efficient management of grid resources using a bi-level decision-making architecture for \"processable\" bulk data\nYear: 2007\n\nAbstract: The problem of efficient assignment of resources to perform a given bag-of-tasks in a distributed computing environment has been extensively studied by research communities. To develop an efficient resource assignment mechanism, this paper focuses on a particular type of resource intensive tasks and presents a bi-level decision-making architecture in a grid computing environment. In the proposed architecture, the higher decision-making module has the responsibility to select a partition of resources for each of the tasks. The lower decision-making module uses Integer Linear Programming based algorithm to actually assign resources from this selected partition to a particular task from the given set of tasks. This paper analyzes the performance of the proposed architecture at various workload conditions. This architecture can be extended for other types of tasks using the concepts presented.","Title: Load sharing in Call Server clusters\nYear: 2007\n\nAbstract: A Call Server in a telephone switch is responsible for connecting the calling and called subscribers. A cluster of Call Servers that serves the subscribers in a large geographical area can provide geographic redundancy, scalability, reduced operational cost, fault tolerance and load sharing. This paper focuses on load sharing in Call Server clusters, particularly on strategies for redirecting new calls from one Call Server to the other. It investigates relative performances of static and adaptive approaches for effectively handling the load spike's occurring on the system. A detailed simulation model is developed using the OPNET tool. The model is used to study the performance of the Call Server clusters under different load conditions. A comparison of the performances of different redirection policies is presented. The impact of different load sharing thresholds on performance is analyzed and various insights gained into system behavior and performance are described.","Title: Performance of CORBA-Based Client-Server Architectures\nYear: 2002\n\nAbstract: Middleware has been introduced to provide interoperability as well as transparent location of servers in heterogeneous client-server environments. Although such benefits accrue from the use of middleware, careful consideration of system architecture is required to achieve high performance. Based on implementation and measurements made on the system, this paper is concerned with the impact of client-server interaction architecture on the performance of CORBA Systems. CORBA or Common Object Request Broker Architecture, proposed by the Object Management Group, is one of the commonly used standards for middleware architectures. Using a commercially available CORBA compliant ORB software called ORBeline, four different architectures were designed and implemented for client-server interaction on a network of workstations. In the Handle-Driven ORB (H-ORB) architecture, the client gets the address of the server from the agent and communicates with the server directly. In the Forwarding ORB (F-ORB) architecture the client request is automatically forwarded by the agent to the appropriate server which then returns the results of the computations to the client directly. In the Process Planner (P-ORB) architecture, the agent combines request forwarding with concurrent invocation of multiple servers for complex requests that require the services of multiple servers. The Adaptive ORB (A-ORB) combines the functionalities of both the H-ORB and the F-ORB and can switch dynamically from an H-ORB mode to an F-ORB mode and vice versa, depending on the load condition. Our measurements show that the difference samong the performances of these architectures change with a change in the workload. The paper will report on the relative performances of these four architectures under different workload conditions. The results provide insights into system behavior for designers as well as users of systems. In particular, the impact of internode delays, message size, and request service times on the latency and scalability attributes of these architectures is analyzed. A discussion of how agent cloning can improve system performance is also included.","Title: A toolset for performance engineering and software design of client-server systems\nYear: 1995\n\nAbstract: TimeBench/SRVN is a prototype toolset for computer-aided design and performance analysis of software, with an emphasis on distributed client-server systems. The performance behaviour of such systems may defy intuition because it involves factors in the software design (such as the partitioning of the functionality and the frequency with which requests will be made to each server) and in the configuration of the distributed system (including replication of services, the distribution of data, and the speed of network access). The novelty of the tool consists in providing support both for developing design specifications and also for performance analysis. The integrated approach avoids the semantic gap between a designer's domain and the performance modeling domain, and assists the designer to explore factors that impact the performance of a design. The performance models are based on the Stochastic Rendezvous Network (SRVN) formalism for client-server systems with synchronous service requests. The distinctive features of SRVNs are nested services (since servers can also act as clients to other servers) and the existence of two or more phases of service (the first executed while the client is blocked, and the others executed in parallel with the client). TimeBench/SRVN is intended as a demonstration of the concept of an integrated designer/performance interface, and as a research environment for fast analytic solvers for the models. Besides a simulation solver, it offers three approximate analytic solvers based on recent research, a Markovian solver, a technique for finding bounds on the throughput without too many assumptions, and a tool for rapidly exploring the space of possible parameter values.","Title: Scheduling Strategies for Controlling Resource Contention on Multiprocessor Systems\nYear: 1999\n\nAbstract: Multiple processes may contend for shared resources such as variables stored in the shared memory of a multiprocessor system.\n Mechanisms required to preserve data consistency on such systems often lead to a decrease in system performance. This research\n focuses on scheduling policies that control shared resource contention and achieve high capacity and scalability in multiprocessor-based\n applications that include telephone switches and real-time databases. Based on analytic models three different scheduling\n approaches are analyzed.","Title: Engineering CORBA-based systems for high performance\nYear: 2002\n\nAbstract: Inter-operability in heterogeneous distributed systems is often provided with the help of CORBA compliant middleware. Many distributed object computing systems, however, are characterized by limited heterogeneity. Such systems often contain a subset of components that are written in the same programming language and run on top of the same p-Worm. We present engineering techniques that exploit such limited heterogeneity in systems for achieving high system performance. With these techniques components implemented using diverse programming languages and/or platform use a CORBA compliant middleware, whereas the similar components can use a \"flyover\" that employs a separate path between the client and its server and avoids a number of CORBA overheads. Insights into system behavior and performance gained from results of experiments with synthetic workload running on a network of PCs are presented.","Title: Engineering grid applications and middleware for high performance\nYear: 2007\n\nAbstract: Meeting QoS objectives of applications while maintaining high system utilization is a challenging task in multi-institutional Grids. In this paper, we effectively engineer Grid applications and resource management middleware for achieving user satisfaction and high resource utilizations. The paper presents a complete framework based on advance reservations (ARs) for resource management in Grids. The framework is capable of providing QoS guarantees to applications while maintaining high resource utilizations. The paper focuses on the scheduling component of the framework and presents a novel heuristic-based algorithm, Grid Scheduling with Deadlines (GSD), for an NP-Complete problem of scheduling ARs with laxities on a shared resource. GSD can be configured with the help of pluggable strategies to adapt to various workload conditions and needs of the system. The paper studies with the aid of an extensive set of experiments the effect of various workload and system parameters on system performance. It is not always possible to accurately predict the runtimes of the jobs. The paper discusses the impact of error in user-estimated runtimes on system performance and investigates strategies to avoid substandard performance resulting from such inaccuracies. Experimental results demonstrate the efficacy of our methodology.","Title: Partitioning Frameworks For Mobile Web Services Provisioning\nYear: 2011\n\nAbstract: Hosting web services (WSs) on mobile and wireless devices is challenging because of their resource limitations. The few existing works in this area are not suitable for hosting WS applications that involve large and complex business processes. Partitioning a WS application to offload a part of the application to a remote node can alleviate these problems. However, there is more than one way to offload parts of a WS application to remote nodes that lead to different partitioning frameworks. In this paper, we propose and analyse three application partitioning frameworks for mobile WSs and compare their performances. The effects of a number of workload and system parameters (such as the size of WS partitions and the size of data exchanged) are investigated. Insights gained into system behaviour and the relative performances of these partitioning frameworks are presented.","Title: Class-Based Grid Resource Management Strategies for On-Demand Jobs\nYear: 2010\n\nAbstract: Grid computing has emerged as a new paradigm for distributed systems, which promotes sharing of distributed resources. To maximize its benefits, it is essential to discover the resources available on the grid, and then effectively map the jobs to the resources for maximizing a given objective function. This paper focuses on the problem of matching of jobs to resources in a computing grid. Jobs are classified based on their service demands. Matching policies that use only the knowledge of job classes are introduced in this paper; simulation experiments demonstrate the effectiveness of these policies. Under a variety of different workload parameters the proposed matching policies demonstrate a performance comparable to, or better than, the well-known Minimum Completion Time matching policy, which is based on detailed a priori knowledge of jobs and resource characteristics.","Title: A Framework For Automatic Resource Provisioning For Private Clouds\nYear: 2013\n\nAbstract: A private cloud is maintained by an enterprise for its internal use. In such a scenario instead of buying the resources the enterprise can acquire the resources from a public cloud such as the ones provided by Amazon and Microsoft. On conventional systems rigorous analysis of the system and its workload is performed for determining the appropriate number of resources to be deployed on the private cloud. This paper presents a middleware framework that avoids this step of a priori capacity analysis and allows such private cloud owners to provision resources automatically such that a specified grade of service is maintained. The proposed framework performs dynamic resource provisioning that also leads to a reduction of operational cost. Additional resources are acquired during high traffic periods and released during low traffic periods such that the desired grade of service is always maintained. The paper describes the architecture of the framework and the experience gained from a prototype implementation including a preliminary analysis of its performance.","Title: Computation of Bounds and Performance Guarantees for Client-Server Systems Using a Queueing Network Model.\nYear: 1998\n\nAbstract: Multiclass Queueing networks have been suggested by a number of researchers for the performance engineering of client-server systems. A number of implementation mechanisms such as software servers, locks in transaction processing, and critical sections make the application of existing analytic methods for queueing networks difficult for the performance analysis of client-server software and systems. Moreover real systems are unlikely to meet the underlying assumptions required by the exact solution methods that are available. We present a performance bounds technique which is apt for modelling client-server systems and is based on relaxed assumptions about the stochastic behaviour of the system. Models can be solved to give upper and lower bounds on throughputs for different classes of clients. Of particular interest is the lower bound on throughput that gives a performance guarantee that is useful in the conservative design of systems.","Title: Web object-based storage management in proxy caches\nYear: 2006\n\nAbstract: Proxy caches are essential to improve the performance of the World Wide Web and to enhance user perceived latency. Appropriate cache management strategies are crucial to achieve these goals. In our previous work, we have introduced Web object-based caching policies. A Web object consists of the main HTML page and all of its constituent embedded files. Our studies have shown that these policies improve proxy cache performance substantially.In this paper, we propose a new Web object-based policy to manage the storage system of a proxy cache. We propose two techniques to improve the storage system performance. The first technique is concerned with prefetching the related files belonging to a Web object, from the disk to main memory. This prefetching improves performance as most of the files can be provided from the main memory rather than from the proxy disk. The second technique stores the Web object members in contiguous disk blocks in order to reduce the disk access time. We used trace-driven simulations to study the performance improvements one can obtain with these two techniques. Our results show that the first technique by itself provides up to 50% reduction in hit latency, which is the delay involved in providing a hit document by the proxy. An additional 5% improvement can be obtained by incorporating the second technique.","Title: Middleware architecture for sensor-based bridge infrastructure management\nYear: 2012\n\nAbstract: Proper monitoring and maintenance of bridges are crucial for the well being of the society. A university-industry collaborative project supported by the Ontario Centers of Excellence in Canada focuses on researching and developing a resource management middleware for unifying resources distributed across the country to provide the necessary sharing of and inter-operability among diverse resources for bridge infrastructure management. This paper proposes a network-based solution and describes the system architecture devised as well as the choice of technology made for implementing key components.","Title: A measure of program locality and its application\nYear: 1984\n\nAbstract: Although the phenomenon of locality has long been recognized as the single most important characteristic of program behaviour, relatively little work has been done in attempting to measure it. Recent work has led to the development of an intrinsic measure of program locality based on the Bradford-Zipf distribution. Potential applications for such a measure are many, and include the evaluation of program restructuring methods (manual and automatic), the prediction of system performance, the validation of program behaviour models, and the enhanced understanding of the phenomena that characterize program behaviour. A consideration of each of these areas is given in connection with the proposed measure, both to increase confidence in the validity of the measure and to illustrate a methodology for dealing with such problems.","Title: Application level performance optimizations for CORBA-based systems\nYear: 2002\n\nAbstract: Middleware provides inter-operability in a heterogeneous distributed object computing environment. Common Object Request Broker (CORBA) is a standard for middleware proposed by OMG. Although inter-operability is achieved middleware often introduces overheads that impair system performance. This research is concerned with performance enhancement of CORBA-based systems by deploying appropriate techniques at the application level. The paper demonstrates that decisions made by the application software designer and programmer can have a large impact on the performance of a CORBA-based system. The paper presents a set of guidelines that can be used at the design and implementation levels for enhancing system performance. We focus on issues such as reduction of connection set up latency, appropriate techniques for parameter passing, impact of method placement on response time, performance implications of different ways of packing objects in servers and load balancing. Insights into system behavior that highlight the effectiveness of the guidelines as well as capture the relationship between the CORBA compliant middleware and overall application performance are presented.","Title: Performance Analysis of Web Service Replica Selection in an Extranet\nYear: 2007\n\nAbstract: IEEE 802.16/WiMAX-based broadband and mobile wireless access is expected to be a significant component in the next generation (e.g., beyond 3G, 4G) wireless systems. IEEE 802.16/WiMAX standard, which incorporates several advanced radio transmission technologies ...","Title: Engineering resource management middleware for optimizing the performance of clouds processing mapreduce jobs with deadlines\nYear: 2014\n\nAbstract: This paper focuses on devising efficient resource management techniques used by the resource management middleware in clouds that handle MapReduce jobs with end-to-end service level agreements (SLAs) comprising an earliest start time, execution time, and a deadline. This research and development work, performed in collaboration with our industrial partner, presents the formulation of the matchmaking and scheduling problem for MapReduce jobs as an optimization problem using: Mixed Integer Linear Programming (MILP) and Constraint Programming (CP) techniques. In addition to the formulations devised, our experience in implementing the MILP and CP models using various open source as well as commercial software packages is described. Furthermore, a performance evaluation of the different approaches used to implement the formulations is conducted using a variety of different workloads.","Title: Utilizing \"Opaque\" Resources for Revenue Enhancement on Clouds and Grids\nYear: 2011\n\nAbstract: Clouds and grids are distributed resource infrastructures that are subjected to both On Demand (OD) as well as Advance reservation (AR) requests. This paper focuses on the revenue that can be earned on cloud and grid systems using different matchmaking strategies that map requests to resources. Existing research on matchmaking uses a priori knowledge of the local scheduling policy used at the resources. However, in these dynamic and heterogeneous systems having detailed a priori knowledge about all the resources is not always feasible. Thus, traditional matchmaking strategies cannot use the resources for which the local scheduling policies are unknown. This paper discusses how a novel matchmaking strategy that does not use knowledge of the local scheduling policies used at the resources may be deployed in order to utilize these un-used resources and improve the revenue earned by the service providing enterprise. Based on analytic bounds and simulation, insights gained into system behaviour and revenue earned are presented.","Title: Providing Interoperability for Resource Access Using Web Services\nYear: 2010\n\nAbstract: This paper focuses on resource virtualization and interoperability required in the context of large distributed environments such as clouds and grids in which shared resources located on multiple sites are accessed by multiple users. A resource is exposed as a Web service. Techniques for handling two types of resources, a computing resource and a database resource are described. Two different Web service technologies, one based on SOAP and the other on REST are experimented with. A comparison of the two technologies including a performance comparison of two implementations (one using SOAP-based Web services and the other using RESTful Web services) of a computing system exposed as a Web service is presented.","Title: Robust bounds and throughput guarantees for closed multiclass queueing networks\nYear: 1998\n\nAbstract: To use queueing theory for analyzing real computing systems, we may make assumptions that are strictly speaking untrue. The problem is especially severe for multiclass systems with widely differing service times. This paper provides an exact analysis for bounds for systems with greatly relaxed assumptions. Service times can have arbitrary NBUE distributions, different by class even at FIFO nodes. Routing can be arbitrary, including dependencies along the route, provided the number of visits to a device per response cycle is random with a known expectation. Only the mean service time and mean visit rates at nodes need to be specified. A new lower throughput bound is found which gives a minimum guaranteed throughput for each class; together with the familiar multiclass asymptotic upper bounds they give a convex feasible region in a multidimensional throughput space. A detailed analysis is given for queueing network models of systems with infinite-server nodes as well as queueing nodes with various service disciplines: FIFO, processor sharing, and priority (preemptive as well as non-preemptive) scheduling. Because the feasible region may be a complicated shape which is difficult to visualize, the results can be re-interpreted as a set of bounds on the separate throughputs. This is equivalent to a circumscribed rectangular region called the “robust box bounds”. Computation of these bounds is carried out by a novel technique based on interval arithmetic as implemented in BNR Prolog language. A method for computing approximate system throughput from the box bounds is also proposed in the paper. Using Little's law and utilization law with the bounds on throughput bounds on response times and device utilizations are obtained. These analytic techniques can be effectively utilized for analyzing the performance of distributed systems as well as other types of computing systems.","Title: High performance publish/subscribe middleware for mobile wireless networks\nYear: 2007\n\nAbstract: Decoupling, flexible, scalable and asynchronous nature of publish/subscribe paradigms makes them a good choice for mobile wireless networks. However, our research shows that current implementations of publish/subscribe systems as well as the traditional solutions for extending publish/subscribe systems to the mobile domain do not perform well in highly mobile and unreliable wireless settings. We present semi-durable subscriptions, a technique that we have developed to overcome the challenges and the performance concerns publish/subscribe systems face in mobile wireless settings. We discuss the architecture of semi-durable subscriptions and study in detail the effect of various mobility parameters on the performance of semi-durable subscriptions to demonstrate their efficacy in mobile wireless settings. We also discuss system parameters for semi-durable subscriptions and with the help of experimental results demonstrate how these parameters can be controlled to configure a system according to a set of desired characteristics.","Title: Address Resolution in large layer 2 networks for data centers\nYear: 2012\n\nAbstract: This paper proposed a Distributed Address Resolution Protocol (DARP) for large layer 2 networks used in a data center. As data centers continue to grow in size, there is an increased amount of overhead required to resolve network addresses using the traditional Address Resolution Protocol (ARP). The DARP attempts to reduce this overhead for large data centers with thousands of nodes and allow for the resolution of network address with minimal strain on the underlying network infrastructure. By using Distributed Hash Tables (DHTs) as the core data structure technology to maintain address records, we attempt to create a decentralized and reliable service that trades the sporadic overhead associated with current approaches with a consistent and predictable overhead. To determine the viability of the protocol, a series of simulations were developed and run via the OPNET Modeler software package. The simulation results demonstrate that DARP outperforms ARP by reducing the number of messages. Data centersaddress resolution protocoldistributed hash tables.","Title: A Two Level Approach for Managing Resource and Data Intensive Tasks in Grids\nYear: 2008\n\nAbstract: In recent years, Grid computing has emerged as an attractive platform to tackle various large-scale problems, especially in the field of science and engineering. Scheduling Grid resources involves a number of challenging issues, mainly due to the distributed and dynamic nature of the Grids. This paper focuses on the resource allocation for a particular type of resource intensive tasks called Processable Bulk Data Transfer (PBDT) tasks in a Grid environment. The defining trait of a PBDT task is a large raw data-file at a source node that needs to be processed in some way before it can be used at a set of sink nodes. Our scheduling approach uses a Bi-level decision-making architecture. This paper analyzes the performance of the proposed architecture at various workload conditions. This architecture can be extended for other types of tasks using the concepts presented.","Title: Characterisation of programs for scheduling in multiprogrammed parallel systems\nYear: 1991\n\nAbstract: The demand for the effective use of medium-scale shared memory parallel computing systems will soon lead to a desire to multiprogram them. Scheduling in multiprogrammed parallel systems is not currently well-understood. Based on models of systems and scheduling strategies this article focuses on the fundamental principles that underly the scheduling of concurrent jobs on multiprocessor systems. Characterization of parallelism in these jobs is important not only in the context of resource management but also for understanding system behaviour. A number of job characteristics which appropriately represent job parallelism and their relationship to processor scheduling are analysed.","Title: The \"Any-Schedulability\" Criterion for Providing QoS Guarantees through Advance Reservation Requests\nYear: 2009\n\nAbstract: Exact knowledge of the scheduling policy used at every resource on a dynamic heterogeneous environment such as a cloud and a grid deploying a variety of different resources is unlikely to be available. This paper describes techniques for determining whether or not a set of advance reservation requests can meet their deadlines when the details of the scheduling policy deployed at the resource is unknown. A discussion of the techniques including a simulation-based performance analysis is presented.","Title: Performance comparison of processor scheduling strategies in a distributed-memory multicomputer system\nYear: 1997\n\nAbstract: Processor scheduling has received considerable attention in the context of shared memory multiprocessor systems but has not received as much attention in distributed memory multicomputers. Furthermore, most previous research in this area has either used a simulation model or an analytical model in evaluating the performance of various policies. Very often these models neglect several practical aspects of the system and workload. Our goal is to implement processor scheduling policies on a real system and evaluate their performance. We have used a transputer based system to implement two policies-one space sharing policy and one time sharing policy-in order to study the relative performance trade-offs involved. We have also implemented a hybrid space sharing and time sharing policy. We report on the performance sensitivity of these policies to various system and workload parameters","Title: Characterization and Analysis of Software and Computer Systems with Uncertainties and Variabilities\nYear: 2001\n\nAbstract: Conventional solution techniques for analytic performance models of computer and telecommunication systems use single values as inputs. Uncertainties or variabilities in model parameters may exist in many types of systems. Using models with a single aggregated mean value for each parameter for such systems can produce inappropriate and misleading results. This chapter presents intervals and extended histograms for characterizing system parameters that are associated with uncertainty and variability. Adaptation of existing analytic performance evaluation methods to this interval-based parameter characterization is described. The application of this approach is illustrated with two examples: a hierarchical model of a multicomputer system and a queueing network model of an EJB server implementation.","Title: Automated Threat Identification for UML.\nYear: 2010\n\nAbstract: In tandem with the growing important roles of software in modern society is the increasing number of threats to software. Building software systems that are resistant to these threats is one of the greatest challenges in information technology. Threat identification methods for secure software development can be found in the literature. However, none of these methods has involved automatic threat identification based on analyzing UML models. Such an automated approach should offer benefits in terms of speed and accuracy when compared to manual methods, and at the same time be widely applicable due to the ubiquity of UML. This paper addresses this shortcoming by proposing an automated threat identification method based on parsing UML diagrams.","Title: Flyover: a technique for achieving high performance in CORBA-based systems with limited heterogeneity\nYear: 2005\n\nAbstract: Inter-operability in heterogeneous distributed systems is often provided with the help of CORBA compliant middleware. Many distributed object-computing systems, however, are characterised by limited heterogeneity. Such systems often contain a subset of components that are written in the same programming language and run on top of the same platform. Techniques that exploit such limited heterogeneity in systems for achieving high system performance are presented here. While components implemented using diverse programming languages and/or platform use a CORBA compliant middleware, the similar components can use a 'Flyover' that employs a separate path between the client and its server, and avoid a number of CORBA overheads. A prototype of a tool that is used for installing such flyovers in CORBA-based applications is implemented and is described. The performance of flyover-based systems is compared with those of pure CORBA-based systems that use commercial middleware products, under various workload and system parameters. A significantly large performance gain is achieved with the flyover for a range of workload parameters. Insights into system behaviour and performance developed from results of experiments with synthetic workload running on a network of PCs are presented.","Title: Achieving efficiency, quality of service and robustness in multi-organizational Grids\nYear: 2009\n\nAbstract: Scalability, flexibility, quality of service provisioning, efficiency and robustness are the desired characteristics of most computing systems. Although the emerging Grid computing paradigm is scalable and flexible, achieving both efficiency and quality of service provisioning in Grids is a challenging task but is necessary for the wide adoption of Grids. Grid middleware should also be robust to uncertainties such as those in user-estimated runtimes of Grid applications. In this paper, we present a complete middleware framework for Grids that achieves user satisfaction by providing QoS guarantees for Grid applications, cost effectiveness by efficiently utilizing resources and robustness by intelligently handling uncertain runtimes of applications.","Title: A Subscription Coverage Technique for XML Message Dissemination\nYear: 2009\n\nAbstract: In this paper, we present an integrated application-layer and IP-layer multicasting scheme for XML message dissemination, which is achieved by moving subscriptions along with aggregated subscription summary with the aid of a network routing table. We present a distributed subscription aggregation mechanism to reduce the cost of subscription aggregation in a collaborative way. Experimental results demonstrate that for the experiments described in the paper our method achieves 20%–55% performance improvement over the conventional method.","Title: Performance of adaptive CORBA middleware\nYear: 2004\n\nAbstract: Middleware provides inter-operability and transparent location of servers in a heterogeneous distributed environment. A careful design of the middleware software is required, however, for achieving high performance. This research proposes an adaptive middleware architecture for CORBA-based systems. The adaptive middleware agent that maps an object name to the object reference has two modes of operations. In the handle-driven mode, it returns a reference for the requested object to the client that uses this reference to re-send the request for the desired operation to the server, whereas in the forwarding mode it forwards the entire client request to the server. The server upon invocation performs the desired operation and returns the results to the client. An adaptive ORB dynamically switches between these two modes depending on the current system load. Using a commercial middleware product called Orbix-MT, we have implemented a skeletal performance prototype for the adaptive ORB. Based on measurements made on a network of workstations and a synthetic workload we observe that the adaptive ORB can produce a significant benefit in performance in comparison to a pure handle-driven or a pure forwarding ORB. Our measurements provide valuable insights into system behavior and performance.","Title: Application of Relational Interval Arithmetic to Computer Performance Analysis: a Survey\nYear: 1997\n\nAbstract: This paper presents a survey of the existing work in the area of interval-based performance analysis of computing systems. Intervals in performance analysis is required when uncertainties or variabilities exist in the workload parameters for the performance model of the system. Intervals are also useful for computing upper and lower bounds on system performance. Most conventional analytic models accept a set of single valued parameters and produce a single valued model output. Adaptation of these existing models to handle interval parameters require new techniques that use interval arithmetic. Experiences with relational interval arithmetic provided by a constraint logic programming language in solving a number of performance analysis problems in conventional multiprogrammed computers as well as distributed processing systems are described.","Title: Study of Data Distribution Strategies for Parallel I/O Management\nYear: 1996\n\nAbstract: Recent studies have demonstrated that significant I/O operations are performed by a number of different classes of parallel applications. Appropriate I/O management strategies are required however for harnessing the power of parallel I/O. This paper focuses on two I/O management issues that affect system performance in multiprogrammed parallel environments. Characterization of the I/O behavior of parallel applications in terms of four different models is discussed first, followed by an investigation of the performance of a number of different data distribution strategies. Using computer simulations, this research shows I/O characteristics of applications and data distribution have an important effect on system performance. Applications which can simultaneously do computation and I/O, plus strategies that can incorporate centralized I/O management are found to be beneficial for a multiprogrammed parallel environment.","Title: A Flexible Hybrid Architecture for Management of Distributed Web Service Registries\nYear: 2007\n\nAbstract: IEEE 802.16/WiMAX-based broadband and mobile wireless access is expected to be a significant component in the next generation (e.g., beyond 3G, 4G) wireless systems. IEEE 802.16/WiMAX standard, which incorporates several advanced radio transmission technologies ...","Title: Partitioning the WS Execution Environment for Hosting Mobile Web Services\nYear: 2008\n\nAbstract: Hosting web services on mobile and wireless devices is challenging because of their limited resources. A few efforts have been made to facilitate hosting of web services on such devices, but the proposed solutions do not always conform to the multiple web service standards and security frameworks that have been proposed by the web service community. Secondly, the performance of these solutions is often limited due to the resource limitations of mobile devices. In this paper, we propose to address this issue by introducing a novel system partitioning technique to be used by a web service provider so that a few WS components can be executed on an intermediate node. The use of the proposed partitioning technique for a WS execution environment has shown a significant performance improvement. The proposed partitioning technique is analyzed using a prototype WS execution environment hosting sample web services.","Title: Interval-Based Performance Analysis of Computing Systems\nYear: 1995\n\nAbstract: Analytic performance models are often used for predicting the performance of computing systems. Existing models accept single valued parameters as input and produce single valued performance measures as outputs. This research proposes to associate intervals or ranges of values with performance measures and key system parameters. Such an approach is appropriate when exact parameter values are unknown but approximate ranges for parameters may be estimated. Conventional arithmetic cannot handle intervals and interval arithmetic-based techniques are required. The paper reports on the feasibility of application of interval arithmetic in the solution of existing well-known models of computing systems. One of the problems with using interval arithmetic is the potential loosening in the interval for the model output: the computed interval may be wider than the actual interval. A computational method based on the notion of interval splitting is introduced in this paper for controlling this problem. The technique is found to be effective in the context of a number of models.","Title: A Peer-to-Peer Model for XML Publish/Subscribe Services\nYear: 2011\n\nAbstract: This paper focuses on XML content delivery. Techniques for XML publish/subscribe delivery include unicast, flooding, IP multicast, and application-layer multicast. An important issue in the context of the state-of-the-art XML routing schemes is that the cost of filtering and aggregation is incurred at each hop. A new peer-to-peer model for XML pub/sub multicast service is described. The proposed model eliminates the redundant filtering task for intermediate nodes. A comparison of the proposed peer-to-peer model for XML multicast and the conventional application-layer XML multicast is presented. The results reveal that the proposed peer-to-peer model is much more efficient.","Title: Engineering SSL-based systems for enhancing system performance\nYear: 2011\n\nAbstract: Security in a distributed system often comes at the cost of a performance penalty. Due to the CPU time consuming security algorithms used, transferring data using SSL is known to be significantly slow. This paper presents an initial set of research results of a university-industry collaborative research focusing on a performance enhancement technique called security sieve that separates the classified and non-classified components in a document and sends these on a secure and a (faster) non-secure channel respectively. Experimental results presented in the paper demonstrate the effectiveness of the technique.","Title: Experiences with parallel job scheduling on a transputer system\nYear: 1999\n\nAbstract: Both time and space sharing strategies have been proposed for job scheduling in multiprogrammed parallel systems. This paper summarizes the major observations gained from an experimental investigation of these two partition sharing strategies on a Transputer system. A number of factors such as the applications and their software architectures in the multiprogramming mix, the partition sharing strategy, and the partition size are varied and the resulting insights into system performance and scheduling are presented. Space sharing is observed to produce a superior performance in comparison to time sharing for a number of multiprogrammed workloads. Time sharing showed a better performance for workloads with high variability in process execution times, and with high rates of interprocess communication. The relationships between system performance and a number of workload and system characteristics are presented.","Title: The effect of average parallelism and CPU-I/O overlap on application speedup.\nYear: 2000\n\nAbstract: Parallelization of I/O using multiple disk drives is warranted for achieving high performance on systems running CPU and I/O intensive applications. This paper is concerned with the characterization of applications with parallel I/O and the derivation of analytic bounds on speedup. New Characteristics for capturing parallelism in I/O are introduced. These characteristics are used in conjunction with other characteristics available in the literature for the derivation of the bounds. Both parallelism in CPU and I/O operations in applications as well as the degree of overlap between CPU and I/O are observed to have a strong impact on speedup.","Title: Exploiting Web Document Structure to Improve Storage Management in Proxy Caches\nYear: 2002\n\nAbstract: Proxy caches are essential to improve the performance of World Wide Web and to enhance user perceived latency. In this paper, we propose a new Web object based policy to manage the storage system of a proxy cache. We propose two techniques to improve the storage system performance. The first technique is concerned with prefetching the related files belonging to a Web object, from the disk to main memory. This prefetching improves performance as most of the files can be provided from the main memory instead of proxy disk. The second technique stores the Web object members in contiguous disk blocks in order to reduce the disk access time. This in turn reduces the disk response time. We have used trace-driven simulations to study the performance improvements one can obtain with these two techniques.","Title: Performance of publish/subscribe middleware in mobile wireless networks\nYear: 2004\n\nAbstract: Publish/subscribe middlewares are becoming popular for distributed applications because of their flexible and scalable nature. Anonymous and loosely-coupled communication between publisher and subscriber, along with the inherently asynchronous nature of these systems, help them adapt quickly to changing environments, making them a good choice for mobile cellular networks. This paper studies publish/subscribe middleware performance in such networks in detail. As a first step, the paper characterizes a popular implementation of publish/subscribe system for the mobile domain, studying and analyzing the effect of different mobility parameters, which to the best of our knowledge is the first experimental research on the performance behavior of publish/subscribe systems in a mobile wireless domain. As a second step the paper presents the design, implementation and evaluation of middleware level handoffs, a well known solution to extend publish/subscribe systems to a mobile domain, and identifies the performance concerns of such extensions. The results show that such handoff protocols involving two brokers are impractical from a performance perspective under highly dynamic and unreliable mobile wireless settings. The paper identifies the basic reason for the limitations of middleware level handoffs.","Title: SWAT: A Tool for Stress Testing Session-based Web Applications\nYear: 2003\n\nAbstract: Stress testing is essential for effective sizing, capacity planning, and service level management exercises. Unfortunately such testing can be a difficult and time-consuming process. In particular, for session-based Web applications, it is difficult to create synthetic workload traces that simultaneously satisfy inter-request dependencies and match the parameter values of many other attributes of real workloads. This paper describes a workload modeling and generation tool for stress testing session-based Web applications. The Session-based Web Application Tester (SWAT) is a tool built on top of the open source httperf Web request generator. It has features to deduce a compact and flexible representation of complex session-based application workloads, to control the generation of synthetic workload traces for sensitivity analysis exercises, and to efficiently submit synthetic workload traces to a system under study. In this way, SWAT aims to facilitate the stress testing process. We demonstrate the use of SWAT with a case study involving a TPC-W compliant e-commerce system. Experiments show that the workload attributes request mix, session length distribution, and think time distribution can each affect client response time distribution as measured in a controlled environment. We show that SWAT can be used to simultaneously control the parameters of such attributes and therefore support studies that evaluate the sensitivity of system capacity to a range of workload conditions. This paper describes a Session-based Web Application Tester (SWAT). SWAT is a workload modeling and generation tool for session-based systems that is built on top of the open source httperf Web request generator (19). It has features to deduce a compact and flexible representation of complex session-based application workloads, control the generation of synthetic workload traces for sensitivity analysis exercises, and to efficiently submit synthetic workload traces to a system under study. SWAT permits one or more workload parameters to be varied at a time so that their individual and joint impact on system performance can be observed. In this way SWAT can be used to increase confidence in the results of testing exercises. We demonstrate the use of SWAT with a case study involving a TPC-W-compliant (26) e-commerce system operating within a controlled environment. Our results show that the following workload attributes can each have a significant impact on client response time distribution: workload mix , defined as the proportions of different types of requests in the workload; session length distribution , defined as the distribution of the number of requests per session; and, think time distribution , defined as the distribution of the times between successive requests within a session. It follows that these attributes should be considered when stress testing session-based systems. We show how SWAT can be used to establish the sensitivity of the system's capacity to changes in parameters for these attributes.","Title: Performance of scheduling strategies for client-server systems\nYear: 1999\n\nAbstract: Two approaches to the improvement of the performance of client–server systems, multithreading and scheduling of servers, are investigated. Both of these approaches are observed to have a significant impact on system performance. The use of multithreading improves throughput characteristics of systems, whereas the deployment of appropriate scheduling strategies at servers can produce a significant improvement in mean client response times. Based on a simulation model a number of basic questions that are important in the context of scheduling on nonmultithreaded, as well as multithreaded, systems are analyzed. Two important factors, monopolization of servers by large requests and software bottlenecks, are observed to be important in the context of scheduling on client–server systems. Both server scheduling, as well as multithreading, can be used to control these effects and lead to a higher system performance. Scheduling policies based on request characteristics are observed to perform well. A new request characteristic that is useful in the scheduling of client–server systems in the presence of software bottlenecks is proposed. Selection of both the server process, as well as the thread within the server, is required when multiple server, are co-located on the same CPU. A comparison between two scheduling approaches, single level and two level is presented in the paper. The results of this research are useful primarily in the design of operating systems for client–server systems and are also of interest to system designers and users.","Title: On the energy-performance tradeoff for parallel applications\nYear: 2010\n\nAbstract: Improving software performance by deploying parallel software on multiple processors often comes at the cost of increasing energy consumption. This paper focuses on such energy-performance tradeoffs. Techniques for computing bounds on software speedup and energy factor that captures the energy cost are presented. Numeric examples for the bounding techniques lead to valuable insights regarding system behaviour, energy and performance.","Title: A Qos-Aware Web Service Replica Selection Framework For An Extranet\nYear: 2006\n\nAbstract: Business partners in an extranet expect web services to be offered in a timely fashion. Replicating web services may reduce the end-to-end web service response time and add fault tolerance to the system. In this paper, we propose a web service replica selection framework that can be deployed in an extranet. The selection procedure is based on dynamic factors such as communication delays between the web service provider and the web service requester and the workload of the web service provider. To analyze the performance of the framework, two web service replica selection policies are simulated: minU and random. Simulation results show that the minU policy has better response time especially under high load conditions.","Title: An XPath Query Aggregation Algorithm Using a Region Encoding\nYear: 2011\n\nAbstract: XML pub/sub systems have recently emerged as application-layer XML routers. XML-based network traffic is expected to have significant growth. The main problem of the state-of-the-art XML routing schemes is that XML filtering speed often cannot match the XML document arrival speed. The XML filtering speed is propotional to the number of quries which are typically represented as XPath quries. Aggregation is a useful technique for reducing the number of XPath queries. This paper will present a new XPath query aggregation algorithm based on a node region encoding scheme which provides positional information. Compared with the existing aggregation algorithms in the literature, our proposed algorithm can efficiently evaluate the ancestor-descendant and parent-child relationships between any pair of nodes in XPath queries and process a tree-structured query as a unit. Experimental results demonstrate the effectiveness of the proposed algorithm. The performance improvement for the proposed algorithm could be up to 61% compared to the existing XSearch algorithm which is the most efficient algorithm for XPath query aggregation so far.","Title: High performance adaptive middleware for CORBA-based systems\nYear: 2000\n\nAbstract: Middleware provides inter-operability and transparent location of servers in a heterogeneous distributed environment. A careful design of the middleware software is required however for achieving high performance. This research proposes an adaptive middleware architecture for CORBA-based systems. The adaptive middleware agent that maps an object name to the object reference has two modes of operations. In the handle-driven mode it returns a reference for the requested object to the client that uses this reference to re-send the request for the desired operation to the server whereas in the forwarding mode it forwards the entire client request to the server. The server upon invocation performs the desired operation and returns the results to the client. An adaptive ORB dynamically switches between these two modes depending on the current system load. Using a commercial middleware product called Orbix-MT we have implemented a skeletal performance prototype for the adaptive ORB. Based on measurements made on a network of workstations and a synthetic workload we observe that the adaptive ORB can produce a substantial benefit in performance in comparison to a pure handle-driven or a pure forwarding ORB. Our measurements provide valuable insights into system behavior and performance.","Title: Interval Arithmetic for Computing Performance Guarantees in Client-Server Software\nYear: 1991\n\nAbstract: Performance analysis of client-server software systems through bounds on task throughputs is presented. The upper and lower bounds (performance guarantee) are both independent of any assumptions about the stochastic behavior of the client tasks, and make only weak assumptions on the server. The analytic expressions for the bounds however, are not in closed form. A new technique based on interval arithmetic is developed to compute numerical values for the bounds.","Title: Resource management on clouds and grids: challenges and answers\nYear: 2011\n\nAbstract: Grids and more recently clouds are distributed system infrastructures that are rapidly gaining popularity among researchers and users. By providing the ability to acquire resources on demand these systems provide elasticity in resource usage as well as a pay-as-you-go opportunity, both of which can lead to a substantial savings for the system users. Appropriate management of resources by the middleware used by service providers is required however for effectively harnessing the power of the underlying distributed resource infrastructure. The problems range from handling resource heterogeneity, providing adequate security during resource access, allocating resources to user requests efficiently as well as effectively scheduling the requests that are mapped to a given resource. This talk will focus on the challenges associated with resource management on grids and clouds and discuss solutions to some of these problems. Particular attention will be paid to resource allocation and scheduling. Existing literature on resource management on grids and clouds describe techniques that are based on the detailed knowledge of local resource management policies as well as user estimates of resource demands for their requests. It is often impractical to assume such a detailed a priroi knowledge of management policies for all the resources will be available to resource brokers in a large and dynamic heterogeneous environment. Moreover, user estimates of resource demands are often error prone. Performing effective resource management \"in the dark\" and handling such uncertainties associated with the local resource management policies and user estimated resource demands will be discussed. Techniques for providing both user satisfaction by improving the fastness of responses as well as service provider benefits through generation of high revenue will be described.","Title: Techniques for Allocation of Sensors in Shared Wireless Sensor Networks.\nYear: 2015\n\nAbstract: Wireless sensor networks (WSNs) hosting multiple applications are gaining popularity over wireless sensor networks dedicated to a single application. The applications hosted by the WSN may have different characteristics. This research investigates the importance of using information about the characteristics of the applications and the state of the network while allocating the sensor nodes to requests for applications. A number of static and dynamic allocation algorithms are investigated. Results of simulation experiments demonstrate that the lifetime of a WSN can be effectively increased by using information about the applications and the state of the WSN. Insights into the relationship between system performance and various system and workload characteristics gained from the simulation experiments are presented.","Title: A Constraint Programming Based Hadoop Scheduler for Handling MapReduce Jobs with Deadlines on Clouds\nYear: 2015\n\nAbstract: A novel MapReduce constraint programming based matchmaking and scheduling algorithm (MRCP) that can handle MapReduce jobs with deadlines and achieve high system performance is devised. The MRCP algorithm is incorporated into Hadoop, which is a widely used open source implementation of the MapReduce programming model, as a new scheduler called the CP-Scheduler. This paper originates from the collaborative research with our industrial partner concerning the engineering of resource management middleware for high performance. It describes our experiences and the challenges that we encountered in designing and implementing the prototype CP-based Hadoop scheduler. A detailed performance evaluation of the CP-Scheduler is conducted on Amazon EC2 to determine the CP-Scheduler's effectiveness as well as to obtain insights into system behaviour and performance. In addition, the CP-Scheduler's performance is also compared with an earliest deadline first (EDF) Hadoop scheduler, which is implemented by extending Hadoop's default FIFO scheduler. The experimental results demonstrate the effectiveness of the CP-Scheduler's ability to handle an open stream of MapReduce jobs with deadlines in a Hadoop cluster.","Title: Design and Performance Evaluation of Cloud-Based XML Publish/Subscribe Services.\nYear: 2014\n\nAbstract: XML message filtering and routing have been recognized as a standard for data exchange for XML dissemination services. These services are often realized using the Publish/Subscribe (pub/sub) model. The Pub/sub model is commonly used by various web-based systems, such as Web content syndication, RSS feeds, location-based services. Conventional XML filtering and forwarding is an application-layer multicast approach that relies on XML-capable brokers. Those XML-capable brokers are built above the network layer using an overlay model for message dissemination. Such an overlay model introduces a great deal of overhead in terms of initial deployment and subsequent operational cost for those XML-capable brokers that typically are supported by Internet Service Providers (ISPs). In other words, those XML-capable brokers need to be set up across geographically distributed areas and may need to be deployed and maintained even by multiple ISPs or special providers. This paper presents a XML message dissemination system using both the conventional XML multicast model and the peer model executing on a cloud, that can be deployed rapidly without the need of any ISP or special arrangements of physical brokers across the networks. In addition, changes to software deployed in the cloud can be made directly and easily. The paper demonstrates experiments over the Amazon EC2 clouds spanning different geographical locations. In addition, the paper presents a performance comparison between the conventional XML multicast model and the peer model deployed on a cloud.","Title: Automatic Resource Provisioning: A Machine Learning Based Proactive Approach\nYear: 2014\n\nAbstract: This paper concerns dynamic provisioning of cloud resources performed by an intermediary enterprise that provides a private cloud (also referred to as a virtual private cloud) for a single client enterprise using resources acquired on demand from a public cloud. A new proactive technique for auto-scaling of resources that changes the number of resources for the private cloud dynamically based on system load is proposed. The technique that supports both on-demand and advance reservation requests uses machine learning to predict future workload based on past workload. Experimental results demonstrate that the proposed technique can effectively lead to a profit for the intermediary enterprise as well as a reduction of cost for the client enterprise.","Title: A Constraint Programming-Based Resource Management Technique for Processing MapReduce Jobs with SLAs on Clouds\nYear: 2014\n\nAbstract: Clouds that are rapidly gaining in popularity require an effective resource manager that can harness the power of the underlying resource pool, and provide resources on demand to its users. This paper focuses on resource management on clouds for workflow requests characterized by Service Level Agreements (SLAs). Specifically, we devise a novel MapReduce constraint programming based resource manager (MRCP-RM) that can effectively perform matchmaking and scheduling of MapReduce jobs, each characterized by an SLA comprising an earliest start time, execution time, and an end-to-end deadline. Using discrete event simulation a performance evaluation of MRCP-RM is conducted for an open system subjected to a stream of job arrivals. The simulation results demonstrate the effectiveness of the resource manager and provide insights into system behaviour and performance.","Title: Analytic performance estimation of client-server systems with multi-threaded clients\nYear: 1994\n\nAbstract: The authors present an analytical performance model named rendezvous network with multi-threaded clients (RNMTC) for performance analysis of client-server systems. RNMTC is able to model systems with multiple clients inter-communicating with multiple servers which may represent either hardware or software system components. Each system client is described by a precedence graph, and may consist of multiple concurrent execution threads whose number can vary due to fork and join operations. The analytic method for RNMTC proposed is based on hierarchical decomposition: at the higher level the system behaviour is represented by a Markov chain (MC) model whose states correspond to all possible combinations of client execution states; at the lower level a stochastic rendezvous network (SRVN) model with simple clients corresponds to each MC slate. SRVN was previously introduced and MVA approximate analytic solutions are known. The RNMTC model has been used with a number of different test cases and the analytic results were found to be in close agreement with simulation results","Title: The stochastic rendezvous network model for performance of synchronous client-server-like distributed software\nYear: 1995\n\nAbstract: Distributed or parallel software with synchronous communication via rendezvous is found in client-server systems and in proposed open distributed systems, in implementation environments such as Ada, V, remote procedure call systems, in transputer systems, and in specification techniques such as CSP, CCS and LOTOS. The delays induced by rendezvous can cause serious performance problems, which are not easy to estimate using conventional models which focus on hardware contention, or on a restricted view of the parallelism which ignores implementation constraints. Stochastic rendezvous networks are queueing networks of a new type which have been proposed as a modelling framework for these systems. They incorporate the two key phenomena of included service and a second phase of service. This paper extends the model to also incorporate different services or entries associated with each task. Approximations to arrival-instant probabilities are employed with a mean-value analysis framework, to give approximate performance estimates. The method has been applied to moderately large industrial software systems","Title: Engineering mobile wireless publish/subscribe systems for high performance\nYear: 2004\n\nAbstract: The flexible, scalable and asynchronous decoupling nature of publish/subscribe systems makes them a good choice for the mobile wireless domain. Our research investigates the application of publish/subscribe middleware to mobile cellular networks with the focus on their performance in such networks. The results show that current implementations of publish/subscribe systems, as well as the traditional solutions for extending publish/subscribe systems to the mobile domain, do not perform well in highly mobile and unreliable wireless settings. In order to overcome the challenges faced by publish/subscribe systems in a wireless mobile domain, the paper introduces a novel approach called semi-durable subscriptions. We present the semi-durable subscription approach and, through rigorous experimentation, prove its efficacy and superiority over traditional solutions.","Title: Internet-based distributed data acquisition system for fiber-optic sensors\nYear: 2007\n\nAbstract: This paper describes an internet-based distributed data-acquisition system for fiber-optic pressure sensors. There is a great need in industry to coordinate remote resources to perform a common task. The architecture described is based on remote access, via the internet, to a large number of fiber-optic pressure sensors located in different geographical areas. Distribution is done with server applications, which schedule requests for service and control the actual sensor device. Servers also detect conflicts between new requests and their current schedules. Client applica- tions act as virtual instrument panels that dispatch measurement tasks for servers. The architecture supports multiple sensors, which can be added/removed from the system dynamically. As well, there can be multiple clients attempting to access servers simultaneously. Thus, the sensors in question are publicly shared among the various active client applications.","Title: Impact of laxity on scheduling with advance reservations in grids\nYear: 2005\n\nAbstract: Advance reservations (ARs) were introduced for application level dynamic scheduling of resources in a grid infrastructure. Previous research shows that ARs can meet their objectives but at a significant performance cost. We argue that laxity in the reservation window of an AR can help improve the performance of AR scheduling. Scheduling ARs with laxities is an NP-hard problem and in this paper we briefly discuss our scalable algorithm for AR scheduling. Based on simulation, the paper investigates in detail the effect laxity on the system performance.","Title: A Framework to Achieve Guaranteed QoS for Applications and High System Performance in Multi-Institutional Grid Computing\nYear: 2006\n\nAbstract: Providing QoS guarantees to the applications in a multi-institutional Grid is a challenging task. Although advance reservations (ARs) can provide QoS guarantees for the applications, they often seriously degrade system performance for resource owners. In this paper, we present a framework for AR based resource sharing that not only provides QoS guarantees for the applications but also ensures high utilization of the resources. This paper focuses on the application-to-resource mapping component of the framework as our results show that traditional mapping algorithms used with best effort jobs do not perform well for ARs. The paper proposes a set of algorithms for mapping ARs and investigates their performance in detail. The paper then presents a novel algorithm that outperforms a number of other algorithms in almost every respect for a wide range of workload parameters. Rigorous experimentation proves the efficacy of our algorithm and brings important insights into the dynamics of the system.","Title: A Synthetic Workload Generation Technique for Stress Testing Session-Based Systems\nYear: 2006\n\nAbstract: Enterprise applications are often business critical but lack effective synthetic workload generation techniques to evaluate performance. These workloads are characterized by sessions of interdependent requests that often cause and exploit dynamically generated responses. Interrequest dependencies must be reflected in synthetic workloads for these systems to exercise application functions correctly. This poses significant challenges for automating the construction of representative synthetic workloads and manipulating workload characteristics for sensitivity analyses. This paper presents a technique to overcome these problems. Given request logs for a system under study, the technique automatically creates a synthetic workload that has specified characteristics and maintains the correct interrequest dependencies. The technique is demonstrated through a case study involving a TPC-W e--commerce system. Results show that incorrect performance results can be obtained by neglecting interrequest dependencies, thereby highlighting the value of our technique. The study also exploits our technique to investigate the impact of several workload characteristics on system performance. Results establish that high variability in the distributions of session length, session idle times, and request service times can cause increased contention among sessions, leading to poor system responsiveness. To the best of our knowledge, these are the first results of this kind for a session-based system. We believe our technique is of value for studies where fine control over workload is essential.","Title: Scheduling on Wireless Sensor Networks Hosting Multiple Applications\nYear: 2011\n\nAbstract: Wireless Sensor Networks (WSN) consist of sensors that may serve a single application or multiple applications. Effective resource management is important when multiple applications share a WSN. In this research, a number of scheduling algorithms that use varying degrees of knowledge about system and application characteristics are proposed. Simulation results show how scheduling can be made more effective by making use of knowledge about the characteristics of an application, and the network topology. Results of simulation experiments demonstrate that deployment of scheduling algorithms at a proxy that leads to energy savings at the sensors can still give rise to a performance comparable to a system on which scheduling is performed at the individual sensors.","Title: System and application knowledge based scheduling of multiple applications in a WSN\nYear: 2012\n\nAbstract: The paper concerns a wireless sensor network (WSN) hosting multiple applications. The applications vary in terms of their resource requirements such as the number of sensors required by the applications and the location of the required sensors relative to a sink node. The requests for the various applications need to be scheduled in a manner so as to reduce the overall mean response time to the users of the applications. In this research, simulation experiments demonstrate that system performance is greatly improved by using knowledge of system and application characteristics in scheduling multiple applications in a WSN as compared to scheduling based on knowledge free First Come First Served algorithm.","Title: Devising Secure Sockets Layer-based distributed systems: A performance-aware approach\nYear: 2012\n\nAbstract: Sending documents containing sensitive information is commonly performed on distributed systems. To protect the sensitive data in the documents, these documents need to be transmitted over a secure channel. However, secure communications can often increase the data transmission time due to the CPU-intensive operations (e.g. encryption/decryption) that need to be applied to the data before the data transfer. This paper focuses on a performance optimization technique called security sieve, which aims to enhance the performance of SSL/TLS-based data transmission. Security sieve reduces the transmission time of transferring classified documents, which may also contain non-sensitive data, by minimizing the time spent performing the CPU-intensive security-related operations. This paper focuses on highlighting the performance optimization principles/performance patterns that were used and includes a discussion of a prototype implementation. In addition, experimental results are presented to demonstrate the performance enhancement provided by security sieve.","Title: Sensor allocation to multiple applications in shared wireless sensor networks\nYear: 2012\n\nAbstract: A sensor grid is an integration of two technologies: wireless sensor networks and the grid. The sensors deployed in a WSN monitor a phenomenon of interest. The information gained from the WSN is processed in the grid and is used by the users of applications. Multipurpose WSNs have become very popular where the deployed WSNs support more than one application. The research in this extended abstract focuses on WSNs supporting multiple applications. In this work, we focus on allocation, which is a process of determining the sensor nodes that will be selected for executing the requests corresponding to an application. Scheduling, which determines the order in which the application requests submitted to the WSN are executed is performed to improve the mean response time to the users of the applications. Our previous works propose various scheduling algorithms for WSNs hosting multiple applications. In this research, various static and dynamic allocation algorithms are proposed with an attempt to balance the energy consumption amongst the sensor nodes and hence improve the network lifetime of the WSN. Network lifetime is the time when the energy of any sensor node in the WSN falls below a predefined threshold. The proposed algorithms use varying degree of information about the energy consumption at the major energy consuming components of the sensor nodes: the CPU component and the radio component. Simulation experiments are performed to evaluate the performance of the proposed algorithms. This extended abstract presents the preliminary results obtained from the experimentation done so far. The simulation experiments demonstrate that by performing dynamic allocation and by using information about the total energy consumption at the sensor nodes, the lifetime of the WSN can be significantly improved.","Title: An Auto-Scaling Framework for Controlling Enterprise Resources on Clouds\nYear: 2015\n\nAbstract: This paper presents a novel technique for auto-scaling cloud resources provided by an intermediary enterprise which services requests from a client enterprise. The intermediary enterprise acquires resources on demand from a public cloud. A broker is deployed by the intermediary enterprise to handle client requests with service level agreements (SLAs). A reactive auto-scaling algorithm is activated on request arrival and achieves auto-scaling by acquiring new resources for serving the recently arrived request. The technique ensures that a grade of service specified by the client enterprise is satisfied and is based on a profit analysis for the intermediary enterprise. A resources is released after the last request allocated on the resource has completed execution. The paper demonstrates that the proposed reactive auto-scaling technique can effectively lead to a profit for the intermediary enterprise as well as a reduction of cost for the client enterprise.","Title: Predictive Auto-scaling Techniques for Clouds Subjected to Requests with Service Level Agreements\nYear: 2015\n\nAbstract: This paper focuses research focuses on automatic provisioning of cloud resources performed by an intermediary enterprise that provides a virtual private cloud for a single client enterprise by using resources from a public cloud. This paper concerns auto-scaling techniques for dynamically controlling the number of resources used by the client enterprise. We focus on proactive auto-scaling that is based on predictions of future workload based on the past workload. The primary goal of the auto-scaling techniques is to achieve a profit for the intermediary enterprise while maintaining a desired grade of service for the client enterprise. The technique supports both on demand requests and requests with service level agreements (SLAs). This paper presents an auto-scaling algorithm and includes a discussion of system design and implementation experience for a prototype system that implements the technique. A detailed performance analysis based on measurements made on the prototype is presented.","Title: A Cloud-Based Platform for Supporting Research Collaboration\nYear: 2015\n\nAbstract: This paper describes a cloud-based platform, called RP-SMARF, for supporting research collaboration in the area of smart facilities management. More precisely, the proposed system delivers sophisticated domain-specific services to users by linking together disparate privately-owned elements such as data repositories, specialized hardware resources and specialized software applications into a unified framework. This allows research collaborators within a knowledge domain to easily run complex applications developed by researchers within the domain on complex datasets. Both batch-type processing as well as interactive application access are supported by the platform. The processing of live data streams generated in one site by an application residing in another site can also be performed. An authorization framework allows element owners to precisely control which users can access various elements. RP-SMARF unifies geographically dispersed heterogeneous resources for research collaborators. This simplifies making software created by researchers more usable by other researchers thereby making many researchers more productive.","Title: A Constraint Programming Based Energy Aware Resource Management Middleware for Clouds Processing MapReduce Jobs with Deadlines.\nYear: 2016\n\nAbstract: This paper concerns guarantees on system performance through Service Level Agreement (SLA) compliance and focuses on devising energy aware resource management techniques based on Dynamic Voltage and Frequency Scaling (DVFS) used by resource management middleware in clouds that handle MapReduce jobs. This research formulates the resource management problem as an optimization problem using Constraint Programming (CP). Experimental results presented in the paper demonstrate the effectiveness of the technique.","Title: Energy aware green spine switch management for Spine-Leaf datacenter networks\nYear: 2015\n\nAbstract: A significant proportion of the operational cost for datacenters is attributed to their energy consumption. Using advanced virtualization techniques in datacenters is enabling the control of electricity use in servers. However, as servers are becoming more energy-proportional, datacenter networks are starting to consume a greater portion of overall power although networks devices often remain under-utilized. This paper proposes an energy aware management technique for reducing the consumption of energy by the network for a Spine-Leaf topology-based datacenter. The main idea of the system is to keep track of the dynamic workload and enable only switches that are necessary for handling the current network traffic. We have developed an energy aware management system for dynamically controlling the number of Spine switches in Spine-Leaf datacenter networks and performed simulation using CloudSim for a number of scenarios. The simulation results show that the system can work effectively to save energy by as much as 63% of the energy consumed by a datacenter comprising a fixed static set of Spine switches.","Title: Efficient message delivery models for XML-based publish/subscribe systems.\nYear: 2016\n\nAbstract: XML-based publish/subscribe (pub/sub) systems have been receiving a great deal of attention from the academic community and the industry. This research focuses on efficient pub/sub systems and considers the devising of XML-based pub/sub systems from the perspective of subscription/query and publication message delivery. Existing research mainly focuses on the efficiency of XML publication message filtering algorithms. Not much research, however, has considered using the system or the communication model in the context of XML publication messages delivery. This paper presents innovative XML delivery techniques, the cross-layer model and the peer model; both techniques make use of publisher and customer edge brokers for efficient XML subscription aggregation and publication message delivery. The primary contribution of the proposed models is the reduction of the number of XML publication message filtering and XPath query aggregation operations performed in the conventional filter-based XML multicast model, which has a high computational overhead. The main idea is to store user subscriptions at customer and publisher edge brokers which are either directly connected or close to the subscribers and the publisher, respectively. We have performed a number of experiments within a controlled local area network (LAN) environment for demonstration of the basic concepts underlying the techniques and in the Amazon cloud environment that emulates the wide area network (WAN). Both the cross-layer and the peer models can reduce the end-to-end (E2E) delay in message delivery. For example, the results obtained from experiments in a LAN demonstrate several-fold performance improvement in E2E delay for both the cross-layer and the peer models compared to the conventional filter-based XML multicast model, and the results using the cloud show an improvement as high as 64% in E2E delay for the peer model over the multicast model.","Title: Green spine switch management for datacenter networks\nYear: 2016\n\nAbstract: Energy consumption for datacenter has grown significantly and the trend is still growing due to the increasing popularity of cloud computing. Datacenter networks (DCNs), however, are starting to consume a greater portion of overall energy in comparison to servers used in datacenters due to advanced virtualization techniques. On the other hand, devices in a DCN often remain under-utilized. There are various DCN architectures. This paper proposes an approach called Green Spine Switch Management System (GSSMS) for Spine-Leaf topology based DCNs. The objective of the approach is to reduce energy consumption used by the network for a Spine-Leaf topology-based datacenter. The primary idea of GSSMS is to monitor the dynamic workload and only keep Spine switches that are necessary for handling the current network traffic. We have developed an adaptive management system to control the number of Spine switches in a Spine-Leaf DCN for efficient energy consumption. Further, we have performed extensive simulation using CloudSim for a number of scenarios. The simulation results demonstrate that our proposed GSSMS can effectively save energy by as much as 63 % of the energy consumed by a datacenter comprising a fixed static set of Spine switches.","Title: MRCP-RM: A Technique for Resource Allocation and Scheduling of MapReduce Jobs with Deadlines\nYear: 2017\n\nAbstract: Resource allocation and scheduling on clouds are required to harness the power of the underlying resource pool such that the service provider can meet the quality of service requirements of users, which are often captured in service level agreements (SLAs). This paper focuses on resource allocation and scheduling on clouds and clusters that process MapReduce jobs with SLAs. The resource allocation and scheduling problem is modelled as an optimization problem using constraint programming, and a novel MapReduce Constraint Programming based Resource Management algorithm (MRCP-RM) is devised that can effectively process an open stream of MapReduce jobs where each job is characterized by an SLA comprising an earliest start time, a required execution time, and an end-to-end deadline. A detailed performance evaluation of MRCP-RM is conducted for an open system subjected to a stream of job arrivals using both simulation and experimentation on a real system. The experiments on a real system are performed on a Hadoop cluster (deployed on Amazon EC2) that runs our new Hadoop Constraint Programming based Resource Management algorithm (HCP-RM) that incorporates a technique for handling data locality. The results of the performance evaluation demonstrate the effectiveness of MRCP-RM/HCP-RM in generating a schedule that leads to a low proportion of jobs missing their deadlines (P) and also provide insights into system behaviour and performance. In the simulation experiments, it is observed that MRCP-RM achieves on average an 82 percent lower P compared to a technique from the existing literature when processing a synthetic workload from Facebook. Furthermore, in the experiments performed on a Hadoop cluster deployed on Amazon EC2, it is observed that HCP-RM achieved on average a 63 percent lower P compared to an EDF-Scheduler for a wide variety of workload and system parameters experimented with.","Title: Energy Aware Resource Management for MapReduce Jobs with Service Level Agreements in Cloud Data Centers\nYear: 2016\n\nAbstract: Clouds which continue to garner interest from practitioners in industry and academia require effective energy aware resource managers to leverage processing power of underlying resources while minimizing energy consumption in global data centers. We devise a novel Energy Aware MapReduce Resource Manager for an open system, called EAMR-RM, that can effectively perform matchmaking and scheduling of MapReduce jobs each of which is characterized by a Service Level Agreement (SLA) for performance that includes a client specified execution time and a deadline such that energy consumption is minimized. Results of the discrete event simulation-based performance analysis demonstrate that the proposed technique can effectively satisfy SLA requirements while achieving up to a 45% reduction in energy consumption compared to approaches which do not consider energy in resource management decisions.","Title: A Greedy Data Association Technique for Multiple Object Tracking\nYear: 2017\n\nAbstract: With recent advancements in complex image analysis algorithms and global optimization techniques, the qualitative performance of Multiple Object Tracking (MOT) has improved significantly, at the cost of slow processing speed. With a focus on high-speed performance, in this paper, we propose a fast data association technique for tracking multiple objects by using Tracking-by-Detection paradigm. Followed by a pre-processing stage of creating reliable tracklets from given detection responses, we propose a threshold-based greedy algorithm that iteratively finds a locally optimum solution with significantly low computational overhead. Experiments conducted on two benchmark datasets show that our method is able to achieve qualitative results comparable to the existing state-of-the-art algorithms with an advantage of 50-600 times faster processing speed.","Title: Techniques for Handling Error in User-estimated Execution Times During Resource Management on Systems Processing MapReduce Jobs.\nYear: 2017\n\nAbstract: In our previous work, we described a resource allocation and scheduling technique for processing an open stream of MapReduce jobs with SLAs (characterized by an earliest start time, an execution time, and a deadline) called the Hadoop Constraint Programming based Resource Management technique (HCP-RM). Since the user-estimated job execution times are used to perform resource allocation and scheduling, error/inaccuracies in the execution times can hinder the ability of HCP-RM from making effective scheduling decisions, leading to a degradation in system performance. This paper focuses on improving the robustness of HCP-RM by introducing a mechanism to handle errors/inaccuracies in user estimates of job execution times that are submitted as part of the job's SLA. A Prescheduling Error Handling technique (PSEH) is devised to adjust the user-estimated execution times of the jobs to make them more accurate before they are used by the resource management algorithm. Results of experiments conducted on a Hadoop cluster deployed on Amazon EC2 demonstrate the effectiveness of the PSEH technique in improving system performance.","Title: A Run Time Technique for Handling Error in User-Estimated Execution Times on Systems Processing MapReduce Jobs with Deadlines\nYear: 2017\n\nAbstract: Effective management of resources on a cloud or cluster is crucial for achieving the quality of service requirements of users, which are typically captured in service level agreements (SLAs). This paper focuses on improving the robustness of resource allocation and scheduling techniques that process an open stream of MapReduce jobs with SLAs, by introducing techniques to handle errors/inaccuracies in user-estimated execution times that are submitted as part of the job's SLA. Inaccuracies in the estimates of task execution times can prevent the resource allocation and scheduling algorithm from making effective scheduling decisions, leading to a degradation in system performance. Techniques for handling error during runtime are presented to handle the situation where jobs have already started executing and their estimated execution times are inaccurate. A simulation-based performance evaluation of the error handling techniques is conducted, which demonstrates that the techniques are effective in improving system performance.","Title: Priority Based Resource Scheduling Techniques for a Resource Constrained Stream Processing System.\nYear: 2017\n\nAbstract: A multitenant Storm cluster runs multiple stream processing applications and uses the default Isolation Scheduler to schedule them. Isolation Scheduler assigns resources to topologies based on static resource configuration and does not provide any means for prioritizing topologies based on their varying business requirements. Thus, performance degradation, even complete starvation of topologies with high priority is possible when the cluster is resource constrained and comprises an inadequate number of resources. Two priority based resource scheduling techniques are proposed to overcome these problems. A performance analysis based on prototyping and measurements demonstrates the effectiveness of the proposed techniques.","Title: Auto-Resource Provisioning for MapReduce-Based Multiple Object Tracking in Video.\nYear: 2018\n\nAbstract: Use of complex image analysis and globally optimal techniques make the current Multiple Object Tracking (MOT) methods for video analysis computationally slow. An important issue in this context is meeting the specific latency requirement for a given application while processing large scale video data. This is especially important in emergency situations such as accidents, natural calamities, and terrorist attacks. This paper introduces a latency reducing MapReduce/Hadoop-based parallel solution for MOT. The system includes an Auto-Resource Provisioning technique for determining the number of Hadoop nodes required to process the MOT job within a user specified deadline. The estimated number of nodes are then provisioned by the system and the MOT application is executed on the Hadoop cluster comprising the desired number of nodes. A prototype is built using the AWS EC2 cloud. A performance analysis is performed using measurements made on the prototype and insights gained into system behavior and performance are presented.","Title: Mapreduce-Based Techniques For Multiple Object Tracking In Video Analytics\nYear: 2017\n\nAbstract: Multiple Object Tracking (MOT) has been deployed effectively in various applications including automated video surveillance, self-driving vehicles, robotics, and medical imaging. Despite improvements in the qualitative performance (accuracy) of the existing state-of-the-art MOT methods through complex image analysis and global optimization techniques, a high computational cost is still a performance limitation. This paper focuses on achieving a high computational speed and proposes three parallel MOT techniques based on MapReduce. This paper introduces techniques that provide a parallel solution which effectively handles the challenges of time-dependencies among the various sections of the video file processed during MOT. Through performance analysis of a prototype deployed on the Amazon EC2 cloud, this paper shows that the proposed techniques provide a scalable solution for parallelizing the MOT methods and achieves an efficiency and speedup of up to 77% and 17 respectively, for a large video file, on a 20 node Hadoop cluster.","Title: Complex Event Recognition Notification Methodology for Uncertain IoT Systems Based on Micro-Service Architecture\nYear: 2018\n\nAbstract: One of the main purposes of the Internet of Things (IoT) systems is to provide information on the observed physical system and to notify when a certain observed complex event occurs in the system. The biggest challenge of the IoT systems is that the systems collect a massive amount of uncertain data from diverse IoT devices, where the devices are connected through the internet. In addition to that, some events are inferred from other events and uncertainty is propagated from parent events to the inferred events, which additionally contributes to overall system uncertainty. The observed complex events are a complex relationship of primitive events that are produced by IoT devices and collected in IoT system. There were a couple of attempts to quantify the system uncertainty by estimating the likelihood of the occurrence of events of interest while taking into account the uncertain data and uncertain parameters of the model of the physical system with rule-based complex event processing and/or Bayesian network. These methods were implemented as stand-alone software solutions that are unable to scale under heavy loads of incoming events. This paper proposes a micro-service based notification methodology that uses complex event recognition to handle the IoT system uncertainty.","Title: A Mobile Complex Event Processing System for Remote Patient Monitoring\nYear: 2018\n\nAbstract: Complex Event Processing (CEP) is widely used for Remote Patient Monitoring (RPM). However, the state-of-the-art techniques use a centralized server to receive health sensor streams and detect complex events. This paper introduces an Internet of Things (IoT) based CEP approach that uses a mobile device on the edge and a remote IoT Hospital Server (IHS) deployed on the cloud. The prototype implementation of the system uses an open-source Siddhi CEP engine on the mobile device and an open-source Web Services Oxygen (WSO2) IoT Server on the IHS. In this architecture, complete complex event detection is performed on the edge and the complex event streams are sent to the hospital server using the Message Queuing Telemetry Transport (MQTT) protocol. The MQTT broker forwards complex event streams to an event listener service running on the hospital server that notifies the hospital staff. Advantages of performing CEP on the edge include circumventing out-of-order delivery of various health sensor streams, avoiding queuing delays at the hospital server and reducing the user cost for data transfer between the mobile device and the hospital server. Also, this technique provides the ability to generate local alarms for the patient even when the mobile network connecting the device to the hospital server is unavailable.","Title: A Fast-Iterative Data Association Technique For Multiple Object Tracking\nYear: 2018\n\nAbstract: A massive amount of video data is recorded daily for forensic post analysis and computer vision applications. The analyses of this data often require multiple object tracking (MOT). Advancements in image analysis algorithms and global optimization techniques have improved the accuracy of MOT, often at the cost of slow processing speed which limits its applications only to small video datasets. With the focus on speed, a fast-iterative data association technique (FIDA) for MOT that uses a tracking-by-detection paradigm and finds a locally optimal solution with a low computational overhead is introduced. The performance analyses conducted on a set of benchmark video datasets show that the proposed technique is significantly faster (50-600 times) than the existing state-of-the-art techniques that produce a comparable tracking accuracy.","Title: A priority based resource scheduling technique for multitenant storm clusters\nYear: 2016\n\nAbstract: In this work in progress paper, we present our ongoing effort towards devising a priority based resource scheduling technique and framework for apache storm. Apache Storm is a popular distributed real time stream processing engine which has been widely adopted by key players in the industry including YAHOO and Twitter. An application running in storm is called a topology that is characterized by a Directed Acyclic Graph (DAG). To run multiple of such topologies in a storm cluster, storm provides with default, out of the box scheduler called Isolation Scheduler. Isolation Scheduler assigns resources to topologies based on static resource configuration and does not provide any means to prioritize topologies based on their varying business priority. As a result, performance degradation, even complete starvation of topologies with high business priority is possible when available cluster resources are insufficient. A priority based resource scheduling strategy is proposed in this paper to overcome this problem. A preliminary performance evaluation is performed to demonstrate effectiveness of the proposed scheduler over the default storm Isolation Scheduler.","Title: A hybrid auto-scaling technique for clouds processing applications with service level agreements.\nYear: 2017\n\nAbstract: This research focuses on the automatic provisioning of cloud resources by an intermediary enterprise. This enterprise provides a virtual private cloud for a single client enterprise by using resources from a public cloud. The intermediary cloud provider is controlled by a broker that uses techniques to dynamically control the number of resources used by the client enterprise. The research presents a hybrid auto-scaling technique based on a combination of a reactive approach and a proactive approach to scale resources based on user demand. The primary goal of this auto-scaling technique is to achieve a profit for the intermediary enterprise while maintaining a desired grade of service for the client enterprise. The second goal of the technique is to reduce costs for the single client enterprise. The technique supports both on-demand requests and requests with service level agreements (SLAs). This paper describes the auto-scaling algorithms associated with the hybrid technique and includes a discussion of system design and implementation experience for a prototype system. A detailed performance analysis based on simulations and measurements made based on the prototype is presented.","Title: A resource management technique for processing deadline-constrained multi-stage workflows.\nYear: 2017\n\nAbstract: The use of cloud computing that provides resources on demand to various types of users, including enterprises as well as engineering and scientific institutions, is growing rapidly. An effective resource management middleware is necessary to harness the power of the underlying distributed hardware in a cloud. Two of the key operations provided by a resource manager are resource allocation (matchmaking) and scheduling. This paper concerns the problem of matchmaking and scheduling an open stream of multi-stage jobs (or workflows) with Service Level Agreements (SLAs) on a cloud or cluster. Multi-stage jobs require service from multiple system resources and are characterized by multiple phases of execution. This paper presents a resource allocation and scheduling technique called RM-DCWF: Resource Management Technique for Deadline-constrained Workflows that can efficiently matchmake and schedule an open stream of multi-stage jobs with SLAs, where each SLA is characterized by an earliest start time, an execution time, and a deadline. A rigorous simulation-based performance evaluation of RM-DCWF is conducted using synthetic workloads derived from real scientific workflows. In addition, the impact of various system and workload parameters on system performance is investigated. The results of this performance evaluation demonstrate the effectiveness of RM-DCWF as captured in a low number of jobs missing their deadlines.","Title: Data Driven Priority Scheduling on a Spark Streaming System\nYear: 2019\n\nAbstract: Big data has become essential for businesses as it enables companies and organizations to gather insights from their data and use it to determine marketing opportunities, assist decision-making or even to find new business opportunities. Companies spend a great deal of effort collecting large amounts of data, which in some cases must be processed in real-time in order to capitalize on business opportunities. Predicting the expected input load at a given point in time can be very difficult and sometimes impossible. As a result, a great deal of effort is put into creating techniques to address varying input loads. A widely used approach is dynamic resource provisioning, but resource provisioners may not react in time to address the resource shortage which can result in increased processing latencies. This paper presents a priority scheduling technique that can be used in conjunction with dynamic and static resource provisioning. This approach allows users to assign a priority to input data items. The scheduler ensures that higher priority data items are given precedence over lower priority data items. This means that when resources become constrained the higher priority data items receive a greater share of resources and experience lower queueing delays in comparison to low priority items. A prototype for the data driven priority scheduler is implemented on the Spark Streaming system.","Title: A Performance Driven Micro Services-Based Architecture/System for Analyzing Noisy IoT Data\nYear: 2019\n\nAbstract: The Internet of Things (IoT) technology presents a complex and challenging paradigm where a huge amount of noisy raw sensor data is collected in order to observe and detect critical events occurring on the system, and generate alarms when required. The biggest challenge of the IoT systems is that the systems collect a massive amount of uncertain data from diverse IoT devices connected through the network. In addition, some events are inferred from other events and uncertainty is propagated from parent events to the inferred events, which additionally contributes to overall system uncertainty. The observed complex events are a complex relationship of primitive events that are produced by IoT devices and collected in IoT systems. A survey performed on existing prior arts on quantifying uncertainty for complex events concluded that proposed existing solutions are unable to scale under heavy loads of incoming data. This paper presents a micro-service based notification methodology that uses complex event recognition (both complex event processing and probabilistic programming) to handle IoT systems uncertainty. In addition, the paper analyzes and recommends existing big data platforms for processing complex events in IoT systems. The current focus of our work includes research and development of the optimized deadline-based and cost-effective resource allocation algorithm in Apache Spark for Uncertain IoT Notification systems.","Title: AParallel Processing Technique for Extracting and Storing User Specified Data\nYear: 2021\n\nAbstract: Users are often interested in a specific type of data (preferences) available from a large volume of data collected on the system. An efficient and effective system that can only store the user preferred data from the large raw data set helps the users to search for relevant information on time. The motivation behind this paper is to devise such a technique. The technique uses machine learning as ...","Title: A Technique for Extracting User Specified Information from Streaming Data\nYear: 2021\n\nAbstract: Users are often interested in a specific type of data (user-preferred data) from large volumes of data streaming into the system in real-time. An efficient system that only stores user-preferred data from these data can reduce storage space by storing only the user-preferred data and discarding the remaining data. It also reduces the search latency which allows the users to search for relevant inf...","Title: Boolean Logical Operator Driven Selective Data Filtering For Large Datasets\nYear: 2022\n\nAbstract: Specific users of a system processing large data sets are often interested in only a small subset of the large volumes of available data. This paper presents research on a parallel processing based data filtering technique that filters out and stores only the subset of data that is of interest to a given user. A user’s preferences reflecting her/his interest are captured in a set of keywords or phrases which may be used in conjunction with Boolean operators. An Apache Spark based prototype is built and deployed on an Amazon EC2 cloud to demonstrate the viability of the approach and to analyze the performance of the proposed technique.","Title: Methods for Transferring Data from a Compute to a Storage Cloud\nYear: 2022\n\nAbstract: This research, done in collaboration with our industrial partner TELUS, concerns systems that use different platforms for the compute and storage infrastructures thus requiring data transfers between the two platforms. This paper focuses on four different data transfer techniques and analyzes their performance. An architectural framework and a proof-of-concept prototype are described and the analysis of the performance of the data transfer techniques are presented. The performance results described in this paper provide insights into system behavior and the performance of the different data transfer techniques.","Title: SCN-DRL: Scheduler for large-scale Critical Notification applications based on Deep Reinforcement Learning\nYear: 2022\n\nAbstract: A multi-objective Scheduling approach for large-scale microservice Critical Notification system applications (SCN-DRL) based on Deep Reinforcement Learning is presented. This paper addresses optimization for three objectives: cloud service cost, cloud resource utilization, and system notification deadline. Recent advances in the deep reinforcement learning field inspired us to research how to build a solution that learns to manage the cloud container’s resources directly from experience. SCN-DRL is an example solution that translates the containerized microservice cloud cluster scheduling problem into a learning problem. To the best of our knowledge, this is the first work dealing with multi-optimization objectives for critical microservice notification applications using deep reinforcement learning, where the notification load is variable and depends on the results of the other previously prior processed microservice. Our initial results show that SCNDRL performs better than state-of-the-art heuristics and adapts to different workload conditions without a noticeable drop in performance.","Title: Multi-objective optimization for cloud provisioning: A case study in large-scale microservice notification applications\nYear: 2022\n\nAbstract: An approach to optimizing a large-scale microservice deployment for a critical notification system is presented. This paper addresses optimization for three objectives: cloud service cost, cloud resource utilization of CPU, RAM and storage, and meeting the system notification deadlines. To the best of our knowledge, this is the first work dealing with multi-objective optimization for microservice notification applications where the notification load is variable and depends on other priorly executed microservice in request processes. Furthermore, best of our knowledge, this is the first work that is based on multi-objective optimization, analyzing and proposing a Pareto front and optimal list from preselected VM candidates. First, the paper formulates multi-objective optimization problems for microservice-based large-scale notification system applications and provides the mathematical deployment model. Then, based on the expected workload and required multi-objective criteria, the paper proposes a set of algorithms that provide the Pareto front optimal solution for preselecting a Cloud Service provider’s VM type. In the end, the paper presents a case study that demonstrates the use of the proposed technique."],"string":"[\n \"Title: BFilter - A XML Message Filtering and Matching Approach in Publish/Subscribe Systems\\nYear: 2010\\n\\nAbstract: In publish/subscribe systems, XML message filtering performed at application layer is an important operation for XML message multicast. As a specific case of content-based multicast in application layer, XML message multicast depends on the data filtering and matching processes and the forwarding and routing schemes. As the XML data emerges in transition, XML message filtering and matching becomes more and more desirable. BFilter, proposed in this paper, conducts the XML message filtering and matching by leveraging branch points in both the XML document and user query. It evaluates user queries that use backward matching branch points to delay further matching processes until branch points match in the XML document and user query. In this way, XML message filtering can be performed more efficiently as the probability of mismatching is reduced. A number of experiments have been conducted and the results demonstrate that BFilter has better performance than the well-known YFilter for complex queries.\",\n \"Title: Techniques for Achieving High Performance Web Servers\\nYear: 2000\\n\\nAbstract: With increasing bandwidth available to the client and the number of users growing at an exponential rate the Web server can become a performance bottleneck. This paper considers the parallelization of requests to Web pages each of which is composed of a number of embedded objects. The performances of systems in which the embedded objects are distributed across multiple backend servers are analyzed. Parallelization of Web requests gives rise to a significant improvement in performance. Replication of servers is observed to be beneficial especially when the embedded objects in a Web page are not evenly distributed across servers. Load balancing policies used by the dispatcher of Web page requests are investigated. A simple round robin policy for backend server selection gives a better performance compared to the default random policy used by the Apache server.\",\n \"Title: Caching techniques for XML message filtering\\nYear: 2009\\n\\nAbstract: An XML publish/subscribe system is based on filtering XML message streams for a large number of subscriptions expressed in XPath. A major issue on an XML-based publish/subscribe system is its performance. As the number of XML documents and XPath-based subscriptions increases in the system, to provide XML filtering efficiently becomes a challenging problem. Hence, there is an urgent need for optimization techniques to meet this challenge. There are many existing approaches on designing efficient XML filtering engine. Most existing research efforts focus on efficient filtering algorithms for achieving a high system performance or supporting more complex XPath syntax. Each proposed scheme has its advantages and limitations. Not much research, however, has considered using caching in the context of XML filtering. In this paper, we propose two caching schemes to be used in conjunction with an XML filtering engine. First, we present a complete message caching algorithm that is a strict caching policy to reduce the computation cost that accrues from multiple filtering of the same messages, by reusing results of previously processed messages. Second, we investigate a structure-based caching method that is an approximate caching policy for messages sharing the same structure. Performance evaluation for synthetic data and real data both show that complete message caching and structure-based caching schemes are able to achieve significantly better filtering performance (up to 80% for both caching schemes for the message streams experimented with).\",\n \"Title: Performance of resource management algorithms for \\\"Processable Bulk Data Transfer\\\" Tasks in Grid Environments\\nYear: 2008\\n\\nAbstract: Processable Bulk Data Transfer (PBDT) tasks are resource intensive concurrent tasks which involve transfer of a very large amount of data that has to be processed in some way before it can be used at a remote set of destination nodes called the sink nodes. A distributed computing environment, such as the Grid is a popular way to perform these tasks. Focusing on the execution of PBDT tasks in a Grid computing environment, this paper presents an efficient resource allocation mechanism. Due to the resource thirsty nature of these tasks, an efficient resource allocation is essential to perform these tasks while achieving satisfactory performance. The time-complexity of the resource allocation algorithm rises sharply as the available number of resources in the given Grid computing environment is increased making efficient resource allocation a challenge. To meet this challenge, this paper investigates the use of approximate algorithms for the resource allocation. The benefits obtained by using the reduced complexity of the algorithm are weighed against the increased costs incurred during the task execution (due to the inaccuracies in resource allocation introduced by the approximations). This paper describes a number of approximations and discusses under which circumstances such approximations are to be used. The techniques presented in this research can be extended to non-PBDT tasks and other distributed computing environments.\",\n \"Title: Measurement and analysis of locality phases in file referencing behaviour\\nYear: 1986\\n\\nAbstract: Recent research has demonstrated the existence of locality in short-term file referencing behaviour. A detailed study of the dynamic characteristics of file referencing is presented in this paper. The concept of Bounded Locality Intervals from the field of program behaviour has been used to model the locality phases of file referencing behaviour. The model is found to be powerful both from a descriptive point of view and from the perspective of understanding the performance implications of locality properties of file referencing behaviour on file system management.\",\n \"Title: Efficient management of grid resources using a bi-level decision-making architecture for \\\"processable\\\" bulk data\\nYear: 2007\\n\\nAbstract: The problem of efficient assignment of resources to perform a given bag-of-tasks in a distributed computing environment has been extensively studied by research communities. To develop an efficient resource assignment mechanism, this paper focuses on a particular type of resource intensive tasks and presents a bi-level decision-making architecture in a grid computing environment. In the proposed architecture, the higher decision-making module has the responsibility to select a partition of resources for each of the tasks. The lower decision-making module uses Integer Linear Programming based algorithm to actually assign resources from this selected partition to a particular task from the given set of tasks. This paper analyzes the performance of the proposed architecture at various workload conditions. This architecture can be extended for other types of tasks using the concepts presented.\",\n \"Title: Load sharing in Call Server clusters\\nYear: 2007\\n\\nAbstract: A Call Server in a telephone switch is responsible for connecting the calling and called subscribers. A cluster of Call Servers that serves the subscribers in a large geographical area can provide geographic redundancy, scalability, reduced operational cost, fault tolerance and load sharing. This paper focuses on load sharing in Call Server clusters, particularly on strategies for redirecting new calls from one Call Server to the other. It investigates relative performances of static and adaptive approaches for effectively handling the load spike's occurring on the system. A detailed simulation model is developed using the OPNET tool. The model is used to study the performance of the Call Server clusters under different load conditions. A comparison of the performances of different redirection policies is presented. The impact of different load sharing thresholds on performance is analyzed and various insights gained into system behavior and performance are described.\",\n \"Title: Performance of CORBA-Based Client-Server Architectures\\nYear: 2002\\n\\nAbstract: Middleware has been introduced to provide interoperability as well as transparent location of servers in heterogeneous client-server environments. Although such benefits accrue from the use of middleware, careful consideration of system architecture is required to achieve high performance. Based on implementation and measurements made on the system, this paper is concerned with the impact of client-server interaction architecture on the performance of CORBA Systems. CORBA or Common Object Request Broker Architecture, proposed by the Object Management Group, is one of the commonly used standards for middleware architectures. Using a commercially available CORBA compliant ORB software called ORBeline, four different architectures were designed and implemented for client-server interaction on a network of workstations. In the Handle-Driven ORB (H-ORB) architecture, the client gets the address of the server from the agent and communicates with the server directly. In the Forwarding ORB (F-ORB) architecture the client request is automatically forwarded by the agent to the appropriate server which then returns the results of the computations to the client directly. In the Process Planner (P-ORB) architecture, the agent combines request forwarding with concurrent invocation of multiple servers for complex requests that require the services of multiple servers. The Adaptive ORB (A-ORB) combines the functionalities of both the H-ORB and the F-ORB and can switch dynamically from an H-ORB mode to an F-ORB mode and vice versa, depending on the load condition. Our measurements show that the difference samong the performances of these architectures change with a change in the workload. The paper will report on the relative performances of these four architectures under different workload conditions. The results provide insights into system behavior for designers as well as users of systems. In particular, the impact of internode delays, message size, and request service times on the latency and scalability attributes of these architectures is analyzed. A discussion of how agent cloning can improve system performance is also included.\",\n \"Title: A toolset for performance engineering and software design of client-server systems\\nYear: 1995\\n\\nAbstract: TimeBench/SRVN is a prototype toolset for computer-aided design and performance analysis of software, with an emphasis on distributed client-server systems. The performance behaviour of such systems may defy intuition because it involves factors in the software design (such as the partitioning of the functionality and the frequency with which requests will be made to each server) and in the configuration of the distributed system (including replication of services, the distribution of data, and the speed of network access). The novelty of the tool consists in providing support both for developing design specifications and also for performance analysis. The integrated approach avoids the semantic gap between a designer's domain and the performance modeling domain, and assists the designer to explore factors that impact the performance of a design. The performance models are based on the Stochastic Rendezvous Network (SRVN) formalism for client-server systems with synchronous service requests. The distinctive features of SRVNs are nested services (since servers can also act as clients to other servers) and the existence of two or more phases of service (the first executed while the client is blocked, and the others executed in parallel with the client). TimeBench/SRVN is intended as a demonstration of the concept of an integrated designer/performance interface, and as a research environment for fast analytic solvers for the models. Besides a simulation solver, it offers three approximate analytic solvers based on recent research, a Markovian solver, a technique for finding bounds on the throughput without too many assumptions, and a tool for rapidly exploring the space of possible parameter values.\",\n \"Title: Scheduling Strategies for Controlling Resource Contention on Multiprocessor Systems\\nYear: 1999\\n\\nAbstract: Multiple processes may contend for shared resources such as variables stored in the shared memory of a multiprocessor system.\\n Mechanisms required to preserve data consistency on such systems often lead to a decrease in system performance. This research\\n focuses on scheduling policies that control shared resource contention and achieve high capacity and scalability in multiprocessor-based\\n applications that include telephone switches and real-time databases. Based on analytic models three different scheduling\\n approaches are analyzed.\",\n \"Title: Engineering CORBA-based systems for high performance\\nYear: 2002\\n\\nAbstract: Inter-operability in heterogeneous distributed systems is often provided with the help of CORBA compliant middleware. Many distributed object computing systems, however, are characterized by limited heterogeneity. Such systems often contain a subset of components that are written in the same programming language and run on top of the same p-Worm. We present engineering techniques that exploit such limited heterogeneity in systems for achieving high system performance. With these techniques components implemented using diverse programming languages and/or platform use a CORBA compliant middleware, whereas the similar components can use a \\\"flyover\\\" that employs a separate path between the client and its server and avoids a number of CORBA overheads. Insights into system behavior and performance gained from results of experiments with synthetic workload running on a network of PCs are presented.\",\n \"Title: Engineering grid applications and middleware for high performance\\nYear: 2007\\n\\nAbstract: Meeting QoS objectives of applications while maintaining high system utilization is a challenging task in multi-institutional Grids. In this paper, we effectively engineer Grid applications and resource management middleware for achieving user satisfaction and high resource utilizations. The paper presents a complete framework based on advance reservations (ARs) for resource management in Grids. The framework is capable of providing QoS guarantees to applications while maintaining high resource utilizations. The paper focuses on the scheduling component of the framework and presents a novel heuristic-based algorithm, Grid Scheduling with Deadlines (GSD), for an NP-Complete problem of scheduling ARs with laxities on a shared resource. GSD can be configured with the help of pluggable strategies to adapt to various workload conditions and needs of the system. The paper studies with the aid of an extensive set of experiments the effect of various workload and system parameters on system performance. It is not always possible to accurately predict the runtimes of the jobs. The paper discusses the impact of error in user-estimated runtimes on system performance and investigates strategies to avoid substandard performance resulting from such inaccuracies. Experimental results demonstrate the efficacy of our methodology.\",\n \"Title: Partitioning Frameworks For Mobile Web Services Provisioning\\nYear: 2011\\n\\nAbstract: Hosting web services (WSs) on mobile and wireless devices is challenging because of their resource limitations. The few existing works in this area are not suitable for hosting WS applications that involve large and complex business processes. Partitioning a WS application to offload a part of the application to a remote node can alleviate these problems. However, there is more than one way to offload parts of a WS application to remote nodes that lead to different partitioning frameworks. In this paper, we propose and analyse three application partitioning frameworks for mobile WSs and compare their performances. The effects of a number of workload and system parameters (such as the size of WS partitions and the size of data exchanged) are investigated. Insights gained into system behaviour and the relative performances of these partitioning frameworks are presented.\",\n \"Title: Class-Based Grid Resource Management Strategies for On-Demand Jobs\\nYear: 2010\\n\\nAbstract: Grid computing has emerged as a new paradigm for distributed systems, which promotes sharing of distributed resources. To maximize its benefits, it is essential to discover the resources available on the grid, and then effectively map the jobs to the resources for maximizing a given objective function. This paper focuses on the problem of matching of jobs to resources in a computing grid. Jobs are classified based on their service demands. Matching policies that use only the knowledge of job classes are introduced in this paper; simulation experiments demonstrate the effectiveness of these policies. Under a variety of different workload parameters the proposed matching policies demonstrate a performance comparable to, or better than, the well-known Minimum Completion Time matching policy, which is based on detailed a priori knowledge of jobs and resource characteristics.\",\n \"Title: A Framework For Automatic Resource Provisioning For Private Clouds\\nYear: 2013\\n\\nAbstract: A private cloud is maintained by an enterprise for its internal use. In such a scenario instead of buying the resources the enterprise can acquire the resources from a public cloud such as the ones provided by Amazon and Microsoft. On conventional systems rigorous analysis of the system and its workload is performed for determining the appropriate number of resources to be deployed on the private cloud. This paper presents a middleware framework that avoids this step of a priori capacity analysis and allows such private cloud owners to provision resources automatically such that a specified grade of service is maintained. The proposed framework performs dynamic resource provisioning that also leads to a reduction of operational cost. Additional resources are acquired during high traffic periods and released during low traffic periods such that the desired grade of service is always maintained. The paper describes the architecture of the framework and the experience gained from a prototype implementation including a preliminary analysis of its performance.\",\n \"Title: Computation of Bounds and Performance Guarantees for Client-Server Systems Using a Queueing Network Model.\\nYear: 1998\\n\\nAbstract: Multiclass Queueing networks have been suggested by a number of researchers for the performance engineering of client-server systems. A number of implementation mechanisms such as software servers, locks in transaction processing, and critical sections make the application of existing analytic methods for queueing networks difficult for the performance analysis of client-server software and systems. Moreover real systems are unlikely to meet the underlying assumptions required by the exact solution methods that are available. We present a performance bounds technique which is apt for modelling client-server systems and is based on relaxed assumptions about the stochastic behaviour of the system. Models can be solved to give upper and lower bounds on throughputs for different classes of clients. Of particular interest is the lower bound on throughput that gives a performance guarantee that is useful in the conservative design of systems.\",\n \"Title: Web object-based storage management in proxy caches\\nYear: 2006\\n\\nAbstract: Proxy caches are essential to improve the performance of the World Wide Web and to enhance user perceived latency. Appropriate cache management strategies are crucial to achieve these goals. In our previous work, we have introduced Web object-based caching policies. A Web object consists of the main HTML page and all of its constituent embedded files. Our studies have shown that these policies improve proxy cache performance substantially.In this paper, we propose a new Web object-based policy to manage the storage system of a proxy cache. We propose two techniques to improve the storage system performance. The first technique is concerned with prefetching the related files belonging to a Web object, from the disk to main memory. This prefetching improves performance as most of the files can be provided from the main memory rather than from the proxy disk. The second technique stores the Web object members in contiguous disk blocks in order to reduce the disk access time. We used trace-driven simulations to study the performance improvements one can obtain with these two techniques. Our results show that the first technique by itself provides up to 50% reduction in hit latency, which is the delay involved in providing a hit document by the proxy. An additional 5% improvement can be obtained by incorporating the second technique.\",\n \"Title: Middleware architecture for sensor-based bridge infrastructure management\\nYear: 2012\\n\\nAbstract: Proper monitoring and maintenance of bridges are crucial for the well being of the society. A university-industry collaborative project supported by the Ontario Centers of Excellence in Canada focuses on researching and developing a resource management middleware for unifying resources distributed across the country to provide the necessary sharing of and inter-operability among diverse resources for bridge infrastructure management. This paper proposes a network-based solution and describes the system architecture devised as well as the choice of technology made for implementing key components.\",\n \"Title: A measure of program locality and its application\\nYear: 1984\\n\\nAbstract: Although the phenomenon of locality has long been recognized as the single most important characteristic of program behaviour, relatively little work has been done in attempting to measure it. Recent work has led to the development of an intrinsic measure of program locality based on the Bradford-Zipf distribution. Potential applications for such a measure are many, and include the evaluation of program restructuring methods (manual and automatic), the prediction of system performance, the validation of program behaviour models, and the enhanced understanding of the phenomena that characterize program behaviour. A consideration of each of these areas is given in connection with the proposed measure, both to increase confidence in the validity of the measure and to illustrate a methodology for dealing with such problems.\",\n \"Title: Application level performance optimizations for CORBA-based systems\\nYear: 2002\\n\\nAbstract: Middleware provides inter-operability in a heterogeneous distributed object computing environment. Common Object Request Broker (CORBA) is a standard for middleware proposed by OMG. Although inter-operability is achieved middleware often introduces overheads that impair system performance. This research is concerned with performance enhancement of CORBA-based systems by deploying appropriate techniques at the application level. The paper demonstrates that decisions made by the application software designer and programmer can have a large impact on the performance of a CORBA-based system. The paper presents a set of guidelines that can be used at the design and implementation levels for enhancing system performance. We focus on issues such as reduction of connection set up latency, appropriate techniques for parameter passing, impact of method placement on response time, performance implications of different ways of packing objects in servers and load balancing. Insights into system behavior that highlight the effectiveness of the guidelines as well as capture the relationship between the CORBA compliant middleware and overall application performance are presented.\",\n \"Title: Performance Analysis of Web Service Replica Selection in an Extranet\\nYear: 2007\\n\\nAbstract: IEEE 802.16/WiMAX-based broadband and mobile wireless access is expected to be a significant component in the next generation (e.g., beyond 3G, 4G) wireless systems. IEEE 802.16/WiMAX standard, which incorporates several advanced radio transmission technologies ...\",\n \"Title: Engineering resource management middleware for optimizing the performance of clouds processing mapreduce jobs with deadlines\\nYear: 2014\\n\\nAbstract: This paper focuses on devising efficient resource management techniques used by the resource management middleware in clouds that handle MapReduce jobs with end-to-end service level agreements (SLAs) comprising an earliest start time, execution time, and a deadline. This research and development work, performed in collaboration with our industrial partner, presents the formulation of the matchmaking and scheduling problem for MapReduce jobs as an optimization problem using: Mixed Integer Linear Programming (MILP) and Constraint Programming (CP) techniques. In addition to the formulations devised, our experience in implementing the MILP and CP models using various open source as well as commercial software packages is described. Furthermore, a performance evaluation of the different approaches used to implement the formulations is conducted using a variety of different workloads.\",\n \"Title: Utilizing \\\"Opaque\\\" Resources for Revenue Enhancement on Clouds and Grids\\nYear: 2011\\n\\nAbstract: Clouds and grids are distributed resource infrastructures that are subjected to both On Demand (OD) as well as Advance reservation (AR) requests. This paper focuses on the revenue that can be earned on cloud and grid systems using different matchmaking strategies that map requests to resources. Existing research on matchmaking uses a priori knowledge of the local scheduling policy used at the resources. However, in these dynamic and heterogeneous systems having detailed a priori knowledge about all the resources is not always feasible. Thus, traditional matchmaking strategies cannot use the resources for which the local scheduling policies are unknown. This paper discusses how a novel matchmaking strategy that does not use knowledge of the local scheduling policies used at the resources may be deployed in order to utilize these un-used resources and improve the revenue earned by the service providing enterprise. Based on analytic bounds and simulation, insights gained into system behaviour and revenue earned are presented.\",\n \"Title: Providing Interoperability for Resource Access Using Web Services\\nYear: 2010\\n\\nAbstract: This paper focuses on resource virtualization and interoperability required in the context of large distributed environments such as clouds and grids in which shared resources located on multiple sites are accessed by multiple users. A resource is exposed as a Web service. Techniques for handling two types of resources, a computing resource and a database resource are described. Two different Web service technologies, one based on SOAP and the other on REST are experimented with. A comparison of the two technologies including a performance comparison of two implementations (one using SOAP-based Web services and the other using RESTful Web services) of a computing system exposed as a Web service is presented.\",\n \"Title: Robust bounds and throughput guarantees for closed multiclass queueing networks\\nYear: 1998\\n\\nAbstract: To use queueing theory for analyzing real computing systems, we may make assumptions that are strictly speaking untrue. The problem is especially severe for multiclass systems with widely differing service times. This paper provides an exact analysis for bounds for systems with greatly relaxed assumptions. Service times can have arbitrary NBUE distributions, different by class even at FIFO nodes. Routing can be arbitrary, including dependencies along the route, provided the number of visits to a device per response cycle is random with a known expectation. Only the mean service time and mean visit rates at nodes need to be specified. A new lower throughput bound is found which gives a minimum guaranteed throughput for each class; together with the familiar multiclass asymptotic upper bounds they give a convex feasible region in a multidimensional throughput space. A detailed analysis is given for queueing network models of systems with infinite-server nodes as well as queueing nodes with various service disciplines: FIFO, processor sharing, and priority (preemptive as well as non-preemptive) scheduling. Because the feasible region may be a complicated shape which is difficult to visualize, the results can be re-interpreted as a set of bounds on the separate throughputs. This is equivalent to a circumscribed rectangular region called the “robust box bounds”. Computation of these bounds is carried out by a novel technique based on interval arithmetic as implemented in BNR Prolog language. A method for computing approximate system throughput from the box bounds is also proposed in the paper. Using Little's law and utilization law with the bounds on throughput bounds on response times and device utilizations are obtained. These analytic techniques can be effectively utilized for analyzing the performance of distributed systems as well as other types of computing systems.\",\n \"Title: High performance publish/subscribe middleware for mobile wireless networks\\nYear: 2007\\n\\nAbstract: Decoupling, flexible, scalable and asynchronous nature of publish/subscribe paradigms makes them a good choice for mobile wireless networks. However, our research shows that current implementations of publish/subscribe systems as well as the traditional solutions for extending publish/subscribe systems to the mobile domain do not perform well in highly mobile and unreliable wireless settings. We present semi-durable subscriptions, a technique that we have developed to overcome the challenges and the performance concerns publish/subscribe systems face in mobile wireless settings. We discuss the architecture of semi-durable subscriptions and study in detail the effect of various mobility parameters on the performance of semi-durable subscriptions to demonstrate their efficacy in mobile wireless settings. We also discuss system parameters for semi-durable subscriptions and with the help of experimental results demonstrate how these parameters can be controlled to configure a system according to a set of desired characteristics.\",\n \"Title: Address Resolution in large layer 2 networks for data centers\\nYear: 2012\\n\\nAbstract: This paper proposed a Distributed Address Resolution Protocol (DARP) for large layer 2 networks used in a data center. As data centers continue to grow in size, there is an increased amount of overhead required to resolve network addresses using the traditional Address Resolution Protocol (ARP). The DARP attempts to reduce this overhead for large data centers with thousands of nodes and allow for the resolution of network address with minimal strain on the underlying network infrastructure. By using Distributed Hash Tables (DHTs) as the core data structure technology to maintain address records, we attempt to create a decentralized and reliable service that trades the sporadic overhead associated with current approaches with a consistent and predictable overhead. To determine the viability of the protocol, a series of simulations were developed and run via the OPNET Modeler software package. The simulation results demonstrate that DARP outperforms ARP by reducing the number of messages. Data centersaddress resolution protocoldistributed hash tables.\",\n \"Title: A Two Level Approach for Managing Resource and Data Intensive Tasks in Grids\\nYear: 2008\\n\\nAbstract: In recent years, Grid computing has emerged as an attractive platform to tackle various large-scale problems, especially in the field of science and engineering. Scheduling Grid resources involves a number of challenging issues, mainly due to the distributed and dynamic nature of the Grids. This paper focuses on the resource allocation for a particular type of resource intensive tasks called Processable Bulk Data Transfer (PBDT) tasks in a Grid environment. The defining trait of a PBDT task is a large raw data-file at a source node that needs to be processed in some way before it can be used at a set of sink nodes. Our scheduling approach uses a Bi-level decision-making architecture. This paper analyzes the performance of the proposed architecture at various workload conditions. This architecture can be extended for other types of tasks using the concepts presented.\",\n \"Title: Characterisation of programs for scheduling in multiprogrammed parallel systems\\nYear: 1991\\n\\nAbstract: The demand for the effective use of medium-scale shared memory parallel computing systems will soon lead to a desire to multiprogram them. Scheduling in multiprogrammed parallel systems is not currently well-understood. Based on models of systems and scheduling strategies this article focuses on the fundamental principles that underly the scheduling of concurrent jobs on multiprocessor systems. Characterization of parallelism in these jobs is important not only in the context of resource management but also for understanding system behaviour. A number of job characteristics which appropriately represent job parallelism and their relationship to processor scheduling are analysed.\",\n \"Title: The \\\"Any-Schedulability\\\" Criterion for Providing QoS Guarantees through Advance Reservation Requests\\nYear: 2009\\n\\nAbstract: Exact knowledge of the scheduling policy used at every resource on a dynamic heterogeneous environment such as a cloud and a grid deploying a variety of different resources is unlikely to be available. This paper describes techniques for determining whether or not a set of advance reservation requests can meet their deadlines when the details of the scheduling policy deployed at the resource is unknown. A discussion of the techniques including a simulation-based performance analysis is presented.\",\n \"Title: Performance comparison of processor scheduling strategies in a distributed-memory multicomputer system\\nYear: 1997\\n\\nAbstract: Processor scheduling has received considerable attention in the context of shared memory multiprocessor systems but has not received as much attention in distributed memory multicomputers. Furthermore, most previous research in this area has either used a simulation model or an analytical model in evaluating the performance of various policies. Very often these models neglect several practical aspects of the system and workload. Our goal is to implement processor scheduling policies on a real system and evaluate their performance. We have used a transputer based system to implement two policies-one space sharing policy and one time sharing policy-in order to study the relative performance trade-offs involved. We have also implemented a hybrid space sharing and time sharing policy. We report on the performance sensitivity of these policies to various system and workload parameters\",\n \"Title: Characterization and Analysis of Software and Computer Systems with Uncertainties and Variabilities\\nYear: 2001\\n\\nAbstract: Conventional solution techniques for analytic performance models of computer and telecommunication systems use single values as inputs. Uncertainties or variabilities in model parameters may exist in many types of systems. Using models with a single aggregated mean value for each parameter for such systems can produce inappropriate and misleading results. This chapter presents intervals and extended histograms for characterizing system parameters that are associated with uncertainty and variability. Adaptation of existing analytic performance evaluation methods to this interval-based parameter characterization is described. The application of this approach is illustrated with two examples: a hierarchical model of a multicomputer system and a queueing network model of an EJB server implementation.\",\n \"Title: Automated Threat Identification for UML.\\nYear: 2010\\n\\nAbstract: In tandem with the growing important roles of software in modern society is the increasing number of threats to software. Building software systems that are resistant to these threats is one of the greatest challenges in information technology. Threat identification methods for secure software development can be found in the literature. However, none of these methods has involved automatic threat identification based on analyzing UML models. Such an automated approach should offer benefits in terms of speed and accuracy when compared to manual methods, and at the same time be widely applicable due to the ubiquity of UML. This paper addresses this shortcoming by proposing an automated threat identification method based on parsing UML diagrams.\",\n \"Title: Flyover: a technique for achieving high performance in CORBA-based systems with limited heterogeneity\\nYear: 2005\\n\\nAbstract: Inter-operability in heterogeneous distributed systems is often provided with the help of CORBA compliant middleware. Many distributed object-computing systems, however, are characterised by limited heterogeneity. Such systems often contain a subset of components that are written in the same programming language and run on top of the same platform. Techniques that exploit such limited heterogeneity in systems for achieving high system performance are presented here. While components implemented using diverse programming languages and/or platform use a CORBA compliant middleware, the similar components can use a 'Flyover' that employs a separate path between the client and its server, and avoid a number of CORBA overheads. A prototype of a tool that is used for installing such flyovers in CORBA-based applications is implemented and is described. The performance of flyover-based systems is compared with those of pure CORBA-based systems that use commercial middleware products, under various workload and system parameters. A significantly large performance gain is achieved with the flyover for a range of workload parameters. Insights into system behaviour and performance developed from results of experiments with synthetic workload running on a network of PCs are presented.\",\n \"Title: Achieving efficiency, quality of service and robustness in multi-organizational Grids\\nYear: 2009\\n\\nAbstract: Scalability, flexibility, quality of service provisioning, efficiency and robustness are the desired characteristics of most computing systems. Although the emerging Grid computing paradigm is scalable and flexible, achieving both efficiency and quality of service provisioning in Grids is a challenging task but is necessary for the wide adoption of Grids. Grid middleware should also be robust to uncertainties such as those in user-estimated runtimes of Grid applications. In this paper, we present a complete middleware framework for Grids that achieves user satisfaction by providing QoS guarantees for Grid applications, cost effectiveness by efficiently utilizing resources and robustness by intelligently handling uncertain runtimes of applications.\",\n \"Title: A Subscription Coverage Technique for XML Message Dissemination\\nYear: 2009\\n\\nAbstract: In this paper, we present an integrated application-layer and IP-layer multicasting scheme for XML message dissemination, which is achieved by moving subscriptions along with aggregated subscription summary with the aid of a network routing table. We present a distributed subscription aggregation mechanism to reduce the cost of subscription aggregation in a collaborative way. Experimental results demonstrate that for the experiments described in the paper our method achieves 20%–55% performance improvement over the conventional method.\",\n \"Title: Performance of adaptive CORBA middleware\\nYear: 2004\\n\\nAbstract: Middleware provides inter-operability and transparent location of servers in a heterogeneous distributed environment. A careful design of the middleware software is required, however, for achieving high performance. This research proposes an adaptive middleware architecture for CORBA-based systems. The adaptive middleware agent that maps an object name to the object reference has two modes of operations. In the handle-driven mode, it returns a reference for the requested object to the client that uses this reference to re-send the request for the desired operation to the server, whereas in the forwarding mode it forwards the entire client request to the server. The server upon invocation performs the desired operation and returns the results to the client. An adaptive ORB dynamically switches between these two modes depending on the current system load. Using a commercial middleware product called Orbix-MT, we have implemented a skeletal performance prototype for the adaptive ORB. Based on measurements made on a network of workstations and a synthetic workload we observe that the adaptive ORB can produce a significant benefit in performance in comparison to a pure handle-driven or a pure forwarding ORB. Our measurements provide valuable insights into system behavior and performance.\",\n \"Title: Application of Relational Interval Arithmetic to Computer Performance Analysis: a Survey\\nYear: 1997\\n\\nAbstract: This paper presents a survey of the existing work in the area of interval-based performance analysis of computing systems. Intervals in performance analysis is required when uncertainties or variabilities exist in the workload parameters for the performance model of the system. Intervals are also useful for computing upper and lower bounds on system performance. Most conventional analytic models accept a set of single valued parameters and produce a single valued model output. Adaptation of these existing models to handle interval parameters require new techniques that use interval arithmetic. Experiences with relational interval arithmetic provided by a constraint logic programming language in solving a number of performance analysis problems in conventional multiprogrammed computers as well as distributed processing systems are described.\",\n \"Title: Study of Data Distribution Strategies for Parallel I/O Management\\nYear: 1996\\n\\nAbstract: Recent studies have demonstrated that significant I/O operations are performed by a number of different classes of parallel applications. Appropriate I/O management strategies are required however for harnessing the power of parallel I/O. This paper focuses on two I/O management issues that affect system performance in multiprogrammed parallel environments. Characterization of the I/O behavior of parallel applications in terms of four different models is discussed first, followed by an investigation of the performance of a number of different data distribution strategies. Using computer simulations, this research shows I/O characteristics of applications and data distribution have an important effect on system performance. Applications which can simultaneously do computation and I/O, plus strategies that can incorporate centralized I/O management are found to be beneficial for a multiprogrammed parallel environment.\",\n \"Title: A Flexible Hybrid Architecture for Management of Distributed Web Service Registries\\nYear: 2007\\n\\nAbstract: IEEE 802.16/WiMAX-based broadband and mobile wireless access is expected to be a significant component in the next generation (e.g., beyond 3G, 4G) wireless systems. IEEE 802.16/WiMAX standard, which incorporates several advanced radio transmission technologies ...\",\n \"Title: Partitioning the WS Execution Environment for Hosting Mobile Web Services\\nYear: 2008\\n\\nAbstract: Hosting web services on mobile and wireless devices is challenging because of their limited resources. A few efforts have been made to facilitate hosting of web services on such devices, but the proposed solutions do not always conform to the multiple web service standards and security frameworks that have been proposed by the web service community. Secondly, the performance of these solutions is often limited due to the resource limitations of mobile devices. In this paper, we propose to address this issue by introducing a novel system partitioning technique to be used by a web service provider so that a few WS components can be executed on an intermediate node. The use of the proposed partitioning technique for a WS execution environment has shown a significant performance improvement. The proposed partitioning technique is analyzed using a prototype WS execution environment hosting sample web services.\",\n \"Title: Interval-Based Performance Analysis of Computing Systems\\nYear: 1995\\n\\nAbstract: Analytic performance models are often used for predicting the performance of computing systems. Existing models accept single valued parameters as input and produce single valued performance measures as outputs. This research proposes to associate intervals or ranges of values with performance measures and key system parameters. Such an approach is appropriate when exact parameter values are unknown but approximate ranges for parameters may be estimated. Conventional arithmetic cannot handle intervals and interval arithmetic-based techniques are required. The paper reports on the feasibility of application of interval arithmetic in the solution of existing well-known models of computing systems. One of the problems with using interval arithmetic is the potential loosening in the interval for the model output: the computed interval may be wider than the actual interval. A computational method based on the notion of interval splitting is introduced in this paper for controlling this problem. The technique is found to be effective in the context of a number of models.\",\n \"Title: A Peer-to-Peer Model for XML Publish/Subscribe Services\\nYear: 2011\\n\\nAbstract: This paper focuses on XML content delivery. Techniques for XML publish/subscribe delivery include unicast, flooding, IP multicast, and application-layer multicast. An important issue in the context of the state-of-the-art XML routing schemes is that the cost of filtering and aggregation is incurred at each hop. A new peer-to-peer model for XML pub/sub multicast service is described. The proposed model eliminates the redundant filtering task for intermediate nodes. A comparison of the proposed peer-to-peer model for XML multicast and the conventional application-layer XML multicast is presented. The results reveal that the proposed peer-to-peer model is much more efficient.\",\n \"Title: Engineering SSL-based systems for enhancing system performance\\nYear: 2011\\n\\nAbstract: Security in a distributed system often comes at the cost of a performance penalty. Due to the CPU time consuming security algorithms used, transferring data using SSL is known to be significantly slow. This paper presents an initial set of research results of a university-industry collaborative research focusing on a performance enhancement technique called security sieve that separates the classified and non-classified components in a document and sends these on a secure and a (faster) non-secure channel respectively. Experimental results presented in the paper demonstrate the effectiveness of the technique.\",\n \"Title: Experiences with parallel job scheduling on a transputer system\\nYear: 1999\\n\\nAbstract: Both time and space sharing strategies have been proposed for job scheduling in multiprogrammed parallel systems. This paper summarizes the major observations gained from an experimental investigation of these two partition sharing strategies on a Transputer system. A number of factors such as the applications and their software architectures in the multiprogramming mix, the partition sharing strategy, and the partition size are varied and the resulting insights into system performance and scheduling are presented. Space sharing is observed to produce a superior performance in comparison to time sharing for a number of multiprogrammed workloads. Time sharing showed a better performance for workloads with high variability in process execution times, and with high rates of interprocess communication. The relationships between system performance and a number of workload and system characteristics are presented.\",\n \"Title: The effect of average parallelism and CPU-I/O overlap on application speedup.\\nYear: 2000\\n\\nAbstract: Parallelization of I/O using multiple disk drives is warranted for achieving high performance on systems running CPU and I/O intensive applications. This paper is concerned with the characterization of applications with parallel I/O and the derivation of analytic bounds on speedup. New Characteristics for capturing parallelism in I/O are introduced. These characteristics are used in conjunction with other characteristics available in the literature for the derivation of the bounds. Both parallelism in CPU and I/O operations in applications as well as the degree of overlap between CPU and I/O are observed to have a strong impact on speedup.\",\n \"Title: Exploiting Web Document Structure to Improve Storage Management in Proxy Caches\\nYear: 2002\\n\\nAbstract: Proxy caches are essential to improve the performance of World Wide Web and to enhance user perceived latency. In this paper, we propose a new Web object based policy to manage the storage system of a proxy cache. We propose two techniques to improve the storage system performance. The first technique is concerned with prefetching the related files belonging to a Web object, from the disk to main memory. This prefetching improves performance as most of the files can be provided from the main memory instead of proxy disk. The second technique stores the Web object members in contiguous disk blocks in order to reduce the disk access time. This in turn reduces the disk response time. We have used trace-driven simulations to study the performance improvements one can obtain with these two techniques.\",\n \"Title: Performance of publish/subscribe middleware in mobile wireless networks\\nYear: 2004\\n\\nAbstract: Publish/subscribe middlewares are becoming popular for distributed applications because of their flexible and scalable nature. Anonymous and loosely-coupled communication between publisher and subscriber, along with the inherently asynchronous nature of these systems, help them adapt quickly to changing environments, making them a good choice for mobile cellular networks. This paper studies publish/subscribe middleware performance in such networks in detail. As a first step, the paper characterizes a popular implementation of publish/subscribe system for the mobile domain, studying and analyzing the effect of different mobility parameters, which to the best of our knowledge is the first experimental research on the performance behavior of publish/subscribe systems in a mobile wireless domain. As a second step the paper presents the design, implementation and evaluation of middleware level handoffs, a well known solution to extend publish/subscribe systems to a mobile domain, and identifies the performance concerns of such extensions. The results show that such handoff protocols involving two brokers are impractical from a performance perspective under highly dynamic and unreliable mobile wireless settings. The paper identifies the basic reason for the limitations of middleware level handoffs.\",\n \"Title: SWAT: A Tool for Stress Testing Session-based Web Applications\\nYear: 2003\\n\\nAbstract: Stress testing is essential for effective sizing, capacity planning, and service level management exercises. Unfortunately such testing can be a difficult and time-consuming process. In particular, for session-based Web applications, it is difficult to create synthetic workload traces that simultaneously satisfy inter-request dependencies and match the parameter values of many other attributes of real workloads. This paper describes a workload modeling and generation tool for stress testing session-based Web applications. The Session-based Web Application Tester (SWAT) is a tool built on top of the open source httperf Web request generator. It has features to deduce a compact and flexible representation of complex session-based application workloads, to control the generation of synthetic workload traces for sensitivity analysis exercises, and to efficiently submit synthetic workload traces to a system under study. In this way, SWAT aims to facilitate the stress testing process. We demonstrate the use of SWAT with a case study involving a TPC-W compliant e-commerce system. Experiments show that the workload attributes request mix, session length distribution, and think time distribution can each affect client response time distribution as measured in a controlled environment. We show that SWAT can be used to simultaneously control the parameters of such attributes and therefore support studies that evaluate the sensitivity of system capacity to a range of workload conditions. This paper describes a Session-based Web Application Tester (SWAT). SWAT is a workload modeling and generation tool for session-based systems that is built on top of the open source httperf Web request generator (19). It has features to deduce a compact and flexible representation of complex session-based application workloads, control the generation of synthetic workload traces for sensitivity analysis exercises, and to efficiently submit synthetic workload traces to a system under study. SWAT permits one or more workload parameters to be varied at a time so that their individual and joint impact on system performance can be observed. In this way SWAT can be used to increase confidence in the results of testing exercises. We demonstrate the use of SWAT with a case study involving a TPC-W-compliant (26) e-commerce system operating within a controlled environment. Our results show that the following workload attributes can each have a significant impact on client response time distribution: workload mix , defined as the proportions of different types of requests in the workload; session length distribution , defined as the distribution of the number of requests per session; and, think time distribution , defined as the distribution of the times between successive requests within a session. It follows that these attributes should be considered when stress testing session-based systems. We show how SWAT can be used to establish the sensitivity of the system's capacity to changes in parameters for these attributes.\",\n \"Title: Performance of scheduling strategies for client-server systems\\nYear: 1999\\n\\nAbstract: Two approaches to the improvement of the performance of client–server systems, multithreading and scheduling of servers, are investigated. Both of these approaches are observed to have a significant impact on system performance. The use of multithreading improves throughput characteristics of systems, whereas the deployment of appropriate scheduling strategies at servers can produce a significant improvement in mean client response times. Based on a simulation model a number of basic questions that are important in the context of scheduling on nonmultithreaded, as well as multithreaded, systems are analyzed. Two important factors, monopolization of servers by large requests and software bottlenecks, are observed to be important in the context of scheduling on client–server systems. Both server scheduling, as well as multithreading, can be used to control these effects and lead to a higher system performance. Scheduling policies based on request characteristics are observed to perform well. A new request characteristic that is useful in the scheduling of client–server systems in the presence of software bottlenecks is proposed. Selection of both the server process, as well as the thread within the server, is required when multiple server, are co-located on the same CPU. A comparison between two scheduling approaches, single level and two level is presented in the paper. The results of this research are useful primarily in the design of operating systems for client–server systems and are also of interest to system designers and users.\",\n \"Title: On the energy-performance tradeoff for parallel applications\\nYear: 2010\\n\\nAbstract: Improving software performance by deploying parallel software on multiple processors often comes at the cost of increasing energy consumption. This paper focuses on such energy-performance tradeoffs. Techniques for computing bounds on software speedup and energy factor that captures the energy cost are presented. Numeric examples for the bounding techniques lead to valuable insights regarding system behaviour, energy and performance.\",\n \"Title: A Qos-Aware Web Service Replica Selection Framework For An Extranet\\nYear: 2006\\n\\nAbstract: Business partners in an extranet expect web services to be offered in a timely fashion. Replicating web services may reduce the end-to-end web service response time and add fault tolerance to the system. In this paper, we propose a web service replica selection framework that can be deployed in an extranet. The selection procedure is based on dynamic factors such as communication delays between the web service provider and the web service requester and the workload of the web service provider. To analyze the performance of the framework, two web service replica selection policies are simulated: minU and random. Simulation results show that the minU policy has better response time especially under high load conditions.\",\n \"Title: An XPath Query Aggregation Algorithm Using a Region Encoding\\nYear: 2011\\n\\nAbstract: XML pub/sub systems have recently emerged as application-layer XML routers. XML-based network traffic is expected to have significant growth. The main problem of the state-of-the-art XML routing schemes is that XML filtering speed often cannot match the XML document arrival speed. The XML filtering speed is propotional to the number of quries which are typically represented as XPath quries. Aggregation is a useful technique for reducing the number of XPath queries. This paper will present a new XPath query aggregation algorithm based on a node region encoding scheme which provides positional information. Compared with the existing aggregation algorithms in the literature, our proposed algorithm can efficiently evaluate the ancestor-descendant and parent-child relationships between any pair of nodes in XPath queries and process a tree-structured query as a unit. Experimental results demonstrate the effectiveness of the proposed algorithm. The performance improvement for the proposed algorithm could be up to 61% compared to the existing XSearch algorithm which is the most efficient algorithm for XPath query aggregation so far.\",\n \"Title: High performance adaptive middleware for CORBA-based systems\\nYear: 2000\\n\\nAbstract: Middleware provides inter-operability and transparent location of servers in a heterogeneous distributed environment. A careful design of the middleware software is required however for achieving high performance. This research proposes an adaptive middleware architecture for CORBA-based systems. The adaptive middleware agent that maps an object name to the object reference has two modes of operations. In the handle-driven mode it returns a reference for the requested object to the client that uses this reference to re-send the request for the desired operation to the server whereas in the forwarding mode it forwards the entire client request to the server. The server upon invocation performs the desired operation and returns the results to the client. An adaptive ORB dynamically switches between these two modes depending on the current system load. Using a commercial middleware product called Orbix-MT we have implemented a skeletal performance prototype for the adaptive ORB. Based on measurements made on a network of workstations and a synthetic workload we observe that the adaptive ORB can produce a substantial benefit in performance in comparison to a pure handle-driven or a pure forwarding ORB. Our measurements provide valuable insights into system behavior and performance.\",\n \"Title: Interval Arithmetic for Computing Performance Guarantees in Client-Server Software\\nYear: 1991\\n\\nAbstract: Performance analysis of client-server software systems through bounds on task throughputs is presented. The upper and lower bounds (performance guarantee) are both independent of any assumptions about the stochastic behavior of the client tasks, and make only weak assumptions on the server. The analytic expressions for the bounds however, are not in closed form. A new technique based on interval arithmetic is developed to compute numerical values for the bounds.\",\n \"Title: Resource management on clouds and grids: challenges and answers\\nYear: 2011\\n\\nAbstract: Grids and more recently clouds are distributed system infrastructures that are rapidly gaining popularity among researchers and users. By providing the ability to acquire resources on demand these systems provide elasticity in resource usage as well as a pay-as-you-go opportunity, both of which can lead to a substantial savings for the system users. Appropriate management of resources by the middleware used by service providers is required however for effectively harnessing the power of the underlying distributed resource infrastructure. The problems range from handling resource heterogeneity, providing adequate security during resource access, allocating resources to user requests efficiently as well as effectively scheduling the requests that are mapped to a given resource. This talk will focus on the challenges associated with resource management on grids and clouds and discuss solutions to some of these problems. Particular attention will be paid to resource allocation and scheduling. Existing literature on resource management on grids and clouds describe techniques that are based on the detailed knowledge of local resource management policies as well as user estimates of resource demands for their requests. It is often impractical to assume such a detailed a priroi knowledge of management policies for all the resources will be available to resource brokers in a large and dynamic heterogeneous environment. Moreover, user estimates of resource demands are often error prone. Performing effective resource management \\\"in the dark\\\" and handling such uncertainties associated with the local resource management policies and user estimated resource demands will be discussed. Techniques for providing both user satisfaction by improving the fastness of responses as well as service provider benefits through generation of high revenue will be described.\",\n \"Title: Techniques for Allocation of Sensors in Shared Wireless Sensor Networks.\\nYear: 2015\\n\\nAbstract: Wireless sensor networks (WSNs) hosting multiple applications are gaining popularity over wireless sensor networks dedicated to a single application. The applications hosted by the WSN may have different characteristics. This research investigates the importance of using information about the characteristics of the applications and the state of the network while allocating the sensor nodes to requests for applications. A number of static and dynamic allocation algorithms are investigated. Results of simulation experiments demonstrate that the lifetime of a WSN can be effectively increased by using information about the applications and the state of the WSN. Insights into the relationship between system performance and various system and workload characteristics gained from the simulation experiments are presented.\",\n \"Title: A Constraint Programming Based Hadoop Scheduler for Handling MapReduce Jobs with Deadlines on Clouds\\nYear: 2015\\n\\nAbstract: A novel MapReduce constraint programming based matchmaking and scheduling algorithm (MRCP) that can handle MapReduce jobs with deadlines and achieve high system performance is devised. The MRCP algorithm is incorporated into Hadoop, which is a widely used open source implementation of the MapReduce programming model, as a new scheduler called the CP-Scheduler. This paper originates from the collaborative research with our industrial partner concerning the engineering of resource management middleware for high performance. It describes our experiences and the challenges that we encountered in designing and implementing the prototype CP-based Hadoop scheduler. A detailed performance evaluation of the CP-Scheduler is conducted on Amazon EC2 to determine the CP-Scheduler's effectiveness as well as to obtain insights into system behaviour and performance. In addition, the CP-Scheduler's performance is also compared with an earliest deadline first (EDF) Hadoop scheduler, which is implemented by extending Hadoop's default FIFO scheduler. The experimental results demonstrate the effectiveness of the CP-Scheduler's ability to handle an open stream of MapReduce jobs with deadlines in a Hadoop cluster.\",\n \"Title: Design and Performance Evaluation of Cloud-Based XML Publish/Subscribe Services.\\nYear: 2014\\n\\nAbstract: XML message filtering and routing have been recognized as a standard for data exchange for XML dissemination services. These services are often realized using the Publish/Subscribe (pub/sub) model. The Pub/sub model is commonly used by various web-based systems, such as Web content syndication, RSS feeds, location-based services. Conventional XML filtering and forwarding is an application-layer multicast approach that relies on XML-capable brokers. Those XML-capable brokers are built above the network layer using an overlay model for message dissemination. Such an overlay model introduces a great deal of overhead in terms of initial deployment and subsequent operational cost for those XML-capable brokers that typically are supported by Internet Service Providers (ISPs). In other words, those XML-capable brokers need to be set up across geographically distributed areas and may need to be deployed and maintained even by multiple ISPs or special providers. This paper presents a XML message dissemination system using both the conventional XML multicast model and the peer model executing on a cloud, that can be deployed rapidly without the need of any ISP or special arrangements of physical brokers across the networks. In addition, changes to software deployed in the cloud can be made directly and easily. The paper demonstrates experiments over the Amazon EC2 clouds spanning different geographical locations. In addition, the paper presents a performance comparison between the conventional XML multicast model and the peer model deployed on a cloud.\",\n \"Title: Automatic Resource Provisioning: A Machine Learning Based Proactive Approach\\nYear: 2014\\n\\nAbstract: This paper concerns dynamic provisioning of cloud resources performed by an intermediary enterprise that provides a private cloud (also referred to as a virtual private cloud) for a single client enterprise using resources acquired on demand from a public cloud. A new proactive technique for auto-scaling of resources that changes the number of resources for the private cloud dynamically based on system load is proposed. The technique that supports both on-demand and advance reservation requests uses machine learning to predict future workload based on past workload. Experimental results demonstrate that the proposed technique can effectively lead to a profit for the intermediary enterprise as well as a reduction of cost for the client enterprise.\",\n \"Title: A Constraint Programming-Based Resource Management Technique for Processing MapReduce Jobs with SLAs on Clouds\\nYear: 2014\\n\\nAbstract: Clouds that are rapidly gaining in popularity require an effective resource manager that can harness the power of the underlying resource pool, and provide resources on demand to its users. This paper focuses on resource management on clouds for workflow requests characterized by Service Level Agreements (SLAs). Specifically, we devise a novel MapReduce constraint programming based resource manager (MRCP-RM) that can effectively perform matchmaking and scheduling of MapReduce jobs, each characterized by an SLA comprising an earliest start time, execution time, and an end-to-end deadline. Using discrete event simulation a performance evaluation of MRCP-RM is conducted for an open system subjected to a stream of job arrivals. The simulation results demonstrate the effectiveness of the resource manager and provide insights into system behaviour and performance.\",\n \"Title: Analytic performance estimation of client-server systems with multi-threaded clients\\nYear: 1994\\n\\nAbstract: The authors present an analytical performance model named rendezvous network with multi-threaded clients (RNMTC) for performance analysis of client-server systems. RNMTC is able to model systems with multiple clients inter-communicating with multiple servers which may represent either hardware or software system components. Each system client is described by a precedence graph, and may consist of multiple concurrent execution threads whose number can vary due to fork and join operations. The analytic method for RNMTC proposed is based on hierarchical decomposition: at the higher level the system behaviour is represented by a Markov chain (MC) model whose states correspond to all possible combinations of client execution states; at the lower level a stochastic rendezvous network (SRVN) model with simple clients corresponds to each MC slate. SRVN was previously introduced and MVA approximate analytic solutions are known. The RNMTC model has been used with a number of different test cases and the analytic results were found to be in close agreement with simulation results\",\n \"Title: The stochastic rendezvous network model for performance of synchronous client-server-like distributed software\\nYear: 1995\\n\\nAbstract: Distributed or parallel software with synchronous communication via rendezvous is found in client-server systems and in proposed open distributed systems, in implementation environments such as Ada, V, remote procedure call systems, in transputer systems, and in specification techniques such as CSP, CCS and LOTOS. The delays induced by rendezvous can cause serious performance problems, which are not easy to estimate using conventional models which focus on hardware contention, or on a restricted view of the parallelism which ignores implementation constraints. Stochastic rendezvous networks are queueing networks of a new type which have been proposed as a modelling framework for these systems. They incorporate the two key phenomena of included service and a second phase of service. This paper extends the model to also incorporate different services or entries associated with each task. Approximations to arrival-instant probabilities are employed with a mean-value analysis framework, to give approximate performance estimates. The method has been applied to moderately large industrial software systems\",\n \"Title: Engineering mobile wireless publish/subscribe systems for high performance\\nYear: 2004\\n\\nAbstract: The flexible, scalable and asynchronous decoupling nature of publish/subscribe systems makes them a good choice for the mobile wireless domain. Our research investigates the application of publish/subscribe middleware to mobile cellular networks with the focus on their performance in such networks. The results show that current implementations of publish/subscribe systems, as well as the traditional solutions for extending publish/subscribe systems to the mobile domain, do not perform well in highly mobile and unreliable wireless settings. In order to overcome the challenges faced by publish/subscribe systems in a wireless mobile domain, the paper introduces a novel approach called semi-durable subscriptions. We present the semi-durable subscription approach and, through rigorous experimentation, prove its efficacy and superiority over traditional solutions.\",\n \"Title: Internet-based distributed data acquisition system for fiber-optic sensors\\nYear: 2007\\n\\nAbstract: This paper describes an internet-based distributed data-acquisition system for fiber-optic pressure sensors. There is a great need in industry to coordinate remote resources to perform a common task. The architecture described is based on remote access, via the internet, to a large number of fiber-optic pressure sensors located in different geographical areas. Distribution is done with server applications, which schedule requests for service and control the actual sensor device. Servers also detect conflicts between new requests and their current schedules. Client applica- tions act as virtual instrument panels that dispatch measurement tasks for servers. The architecture supports multiple sensors, which can be added/removed from the system dynamically. As well, there can be multiple clients attempting to access servers simultaneously. Thus, the sensors in question are publicly shared among the various active client applications.\",\n \"Title: Impact of laxity on scheduling with advance reservations in grids\\nYear: 2005\\n\\nAbstract: Advance reservations (ARs) were introduced for application level dynamic scheduling of resources in a grid infrastructure. Previous research shows that ARs can meet their objectives but at a significant performance cost. We argue that laxity in the reservation window of an AR can help improve the performance of AR scheduling. Scheduling ARs with laxities is an NP-hard problem and in this paper we briefly discuss our scalable algorithm for AR scheduling. Based on simulation, the paper investigates in detail the effect laxity on the system performance.\",\n \"Title: A Framework to Achieve Guaranteed QoS for Applications and High System Performance in Multi-Institutional Grid Computing\\nYear: 2006\\n\\nAbstract: Providing QoS guarantees to the applications in a multi-institutional Grid is a challenging task. Although advance reservations (ARs) can provide QoS guarantees for the applications, they often seriously degrade system performance for resource owners. In this paper, we present a framework for AR based resource sharing that not only provides QoS guarantees for the applications but also ensures high utilization of the resources. This paper focuses on the application-to-resource mapping component of the framework as our results show that traditional mapping algorithms used with best effort jobs do not perform well for ARs. The paper proposes a set of algorithms for mapping ARs and investigates their performance in detail. The paper then presents a novel algorithm that outperforms a number of other algorithms in almost every respect for a wide range of workload parameters. Rigorous experimentation proves the efficacy of our algorithm and brings important insights into the dynamics of the system.\",\n \"Title: A Synthetic Workload Generation Technique for Stress Testing Session-Based Systems\\nYear: 2006\\n\\nAbstract: Enterprise applications are often business critical but lack effective synthetic workload generation techniques to evaluate performance. These workloads are characterized by sessions of interdependent requests that often cause and exploit dynamically generated responses. Interrequest dependencies must be reflected in synthetic workloads for these systems to exercise application functions correctly. This poses significant challenges for automating the construction of representative synthetic workloads and manipulating workload characteristics for sensitivity analyses. This paper presents a technique to overcome these problems. Given request logs for a system under study, the technique automatically creates a synthetic workload that has specified characteristics and maintains the correct interrequest dependencies. The technique is demonstrated through a case study involving a TPC-W e--commerce system. Results show that incorrect performance results can be obtained by neglecting interrequest dependencies, thereby highlighting the value of our technique. The study also exploits our technique to investigate the impact of several workload characteristics on system performance. Results establish that high variability in the distributions of session length, session idle times, and request service times can cause increased contention among sessions, leading to poor system responsiveness. To the best of our knowledge, these are the first results of this kind for a session-based system. We believe our technique is of value for studies where fine control over workload is essential.\",\n \"Title: Scheduling on Wireless Sensor Networks Hosting Multiple Applications\\nYear: 2011\\n\\nAbstract: Wireless Sensor Networks (WSN) consist of sensors that may serve a single application or multiple applications. Effective resource management is important when multiple applications share a WSN. In this research, a number of scheduling algorithms that use varying degrees of knowledge about system and application characteristics are proposed. Simulation results show how scheduling can be made more effective by making use of knowledge about the characteristics of an application, and the network topology. Results of simulation experiments demonstrate that deployment of scheduling algorithms at a proxy that leads to energy savings at the sensors can still give rise to a performance comparable to a system on which scheduling is performed at the individual sensors.\",\n \"Title: System and application knowledge based scheduling of multiple applications in a WSN\\nYear: 2012\\n\\nAbstract: The paper concerns a wireless sensor network (WSN) hosting multiple applications. The applications vary in terms of their resource requirements such as the number of sensors required by the applications and the location of the required sensors relative to a sink node. The requests for the various applications need to be scheduled in a manner so as to reduce the overall mean response time to the users of the applications. In this research, simulation experiments demonstrate that system performance is greatly improved by using knowledge of system and application characteristics in scheduling multiple applications in a WSN as compared to scheduling based on knowledge free First Come First Served algorithm.\",\n \"Title: Devising Secure Sockets Layer-based distributed systems: A performance-aware approach\\nYear: 2012\\n\\nAbstract: Sending documents containing sensitive information is commonly performed on distributed systems. To protect the sensitive data in the documents, these documents need to be transmitted over a secure channel. However, secure communications can often increase the data transmission time due to the CPU-intensive operations (e.g. encryption/decryption) that need to be applied to the data before the data transfer. This paper focuses on a performance optimization technique called security sieve, which aims to enhance the performance of SSL/TLS-based data transmission. Security sieve reduces the transmission time of transferring classified documents, which may also contain non-sensitive data, by minimizing the time spent performing the CPU-intensive security-related operations. This paper focuses on highlighting the performance optimization principles/performance patterns that were used and includes a discussion of a prototype implementation. In addition, experimental results are presented to demonstrate the performance enhancement provided by security sieve.\",\n \"Title: Sensor allocation to multiple applications in shared wireless sensor networks\\nYear: 2012\\n\\nAbstract: A sensor grid is an integration of two technologies: wireless sensor networks and the grid. The sensors deployed in a WSN monitor a phenomenon of interest. The information gained from the WSN is processed in the grid and is used by the users of applications. Multipurpose WSNs have become very popular where the deployed WSNs support more than one application. The research in this extended abstract focuses on WSNs supporting multiple applications. In this work, we focus on allocation, which is a process of determining the sensor nodes that will be selected for executing the requests corresponding to an application. Scheduling, which determines the order in which the application requests submitted to the WSN are executed is performed to improve the mean response time to the users of the applications. Our previous works propose various scheduling algorithms for WSNs hosting multiple applications. In this research, various static and dynamic allocation algorithms are proposed with an attempt to balance the energy consumption amongst the sensor nodes and hence improve the network lifetime of the WSN. Network lifetime is the time when the energy of any sensor node in the WSN falls below a predefined threshold. The proposed algorithms use varying degree of information about the energy consumption at the major energy consuming components of the sensor nodes: the CPU component and the radio component. Simulation experiments are performed to evaluate the performance of the proposed algorithms. This extended abstract presents the preliminary results obtained from the experimentation done so far. The simulation experiments demonstrate that by performing dynamic allocation and by using information about the total energy consumption at the sensor nodes, the lifetime of the WSN can be significantly improved.\",\n \"Title: An Auto-Scaling Framework for Controlling Enterprise Resources on Clouds\\nYear: 2015\\n\\nAbstract: This paper presents a novel technique for auto-scaling cloud resources provided by an intermediary enterprise which services requests from a client enterprise. The intermediary enterprise acquires resources on demand from a public cloud. A broker is deployed by the intermediary enterprise to handle client requests with service level agreements (SLAs). A reactive auto-scaling algorithm is activated on request arrival and achieves auto-scaling by acquiring new resources for serving the recently arrived request. The technique ensures that a grade of service specified by the client enterprise is satisfied and is based on a profit analysis for the intermediary enterprise. A resources is released after the last request allocated on the resource has completed execution. The paper demonstrates that the proposed reactive auto-scaling technique can effectively lead to a profit for the intermediary enterprise as well as a reduction of cost for the client enterprise.\",\n \"Title: Predictive Auto-scaling Techniques for Clouds Subjected to Requests with Service Level Agreements\\nYear: 2015\\n\\nAbstract: This paper focuses research focuses on automatic provisioning of cloud resources performed by an intermediary enterprise that provides a virtual private cloud for a single client enterprise by using resources from a public cloud. This paper concerns auto-scaling techniques for dynamically controlling the number of resources used by the client enterprise. We focus on proactive auto-scaling that is based on predictions of future workload based on the past workload. The primary goal of the auto-scaling techniques is to achieve a profit for the intermediary enterprise while maintaining a desired grade of service for the client enterprise. The technique supports both on demand requests and requests with service level agreements (SLAs). This paper presents an auto-scaling algorithm and includes a discussion of system design and implementation experience for a prototype system that implements the technique. A detailed performance analysis based on measurements made on the prototype is presented.\",\n \"Title: A Cloud-Based Platform for Supporting Research Collaboration\\nYear: 2015\\n\\nAbstract: This paper describes a cloud-based platform, called RP-SMARF, for supporting research collaboration in the area of smart facilities management. More precisely, the proposed system delivers sophisticated domain-specific services to users by linking together disparate privately-owned elements such as data repositories, specialized hardware resources and specialized software applications into a unified framework. This allows research collaborators within a knowledge domain to easily run complex applications developed by researchers within the domain on complex datasets. Both batch-type processing as well as interactive application access are supported by the platform. The processing of live data streams generated in one site by an application residing in another site can also be performed. An authorization framework allows element owners to precisely control which users can access various elements. RP-SMARF unifies geographically dispersed heterogeneous resources for research collaborators. This simplifies making software created by researchers more usable by other researchers thereby making many researchers more productive.\",\n \"Title: A Constraint Programming Based Energy Aware Resource Management Middleware for Clouds Processing MapReduce Jobs with Deadlines.\\nYear: 2016\\n\\nAbstract: This paper concerns guarantees on system performance through Service Level Agreement (SLA) compliance and focuses on devising energy aware resource management techniques based on Dynamic Voltage and Frequency Scaling (DVFS) used by resource management middleware in clouds that handle MapReduce jobs. This research formulates the resource management problem as an optimization problem using Constraint Programming (CP). Experimental results presented in the paper demonstrate the effectiveness of the technique.\",\n \"Title: Energy aware green spine switch management for Spine-Leaf datacenter networks\\nYear: 2015\\n\\nAbstract: A significant proportion of the operational cost for datacenters is attributed to their energy consumption. Using advanced virtualization techniques in datacenters is enabling the control of electricity use in servers. However, as servers are becoming more energy-proportional, datacenter networks are starting to consume a greater portion of overall power although networks devices often remain under-utilized. This paper proposes an energy aware management technique for reducing the consumption of energy by the network for a Spine-Leaf topology-based datacenter. The main idea of the system is to keep track of the dynamic workload and enable only switches that are necessary for handling the current network traffic. We have developed an energy aware management system for dynamically controlling the number of Spine switches in Spine-Leaf datacenter networks and performed simulation using CloudSim for a number of scenarios. The simulation results show that the system can work effectively to save energy by as much as 63% of the energy consumed by a datacenter comprising a fixed static set of Spine switches.\",\n \"Title: Efficient message delivery models for XML-based publish/subscribe systems.\\nYear: 2016\\n\\nAbstract: XML-based publish/subscribe (pub/sub) systems have been receiving a great deal of attention from the academic community and the industry. This research focuses on efficient pub/sub systems and considers the devising of XML-based pub/sub systems from the perspective of subscription/query and publication message delivery. Existing research mainly focuses on the efficiency of XML publication message filtering algorithms. Not much research, however, has considered using the system or the communication model in the context of XML publication messages delivery. This paper presents innovative XML delivery techniques, the cross-layer model and the peer model; both techniques make use of publisher and customer edge brokers for efficient XML subscription aggregation and publication message delivery. The primary contribution of the proposed models is the reduction of the number of XML publication message filtering and XPath query aggregation operations performed in the conventional filter-based XML multicast model, which has a high computational overhead. The main idea is to store user subscriptions at customer and publisher edge brokers which are either directly connected or close to the subscribers and the publisher, respectively. We have performed a number of experiments within a controlled local area network (LAN) environment for demonstration of the basic concepts underlying the techniques and in the Amazon cloud environment that emulates the wide area network (WAN). Both the cross-layer and the peer models can reduce the end-to-end (E2E) delay in message delivery. For example, the results obtained from experiments in a LAN demonstrate several-fold performance improvement in E2E delay for both the cross-layer and the peer models compared to the conventional filter-based XML multicast model, and the results using the cloud show an improvement as high as 64% in E2E delay for the peer model over the multicast model.\",\n \"Title: Green spine switch management for datacenter networks\\nYear: 2016\\n\\nAbstract: Energy consumption for datacenter has grown significantly and the trend is still growing due to the increasing popularity of cloud computing. Datacenter networks (DCNs), however, are starting to consume a greater portion of overall energy in comparison to servers used in datacenters due to advanced virtualization techniques. On the other hand, devices in a DCN often remain under-utilized. There are various DCN architectures. This paper proposes an approach called Green Spine Switch Management System (GSSMS) for Spine-Leaf topology based DCNs. The objective of the approach is to reduce energy consumption used by the network for a Spine-Leaf topology-based datacenter. The primary idea of GSSMS is to monitor the dynamic workload and only keep Spine switches that are necessary for handling the current network traffic. We have developed an adaptive management system to control the number of Spine switches in a Spine-Leaf DCN for efficient energy consumption. Further, we have performed extensive simulation using CloudSim for a number of scenarios. The simulation results demonstrate that our proposed GSSMS can effectively save energy by as much as 63 % of the energy consumed by a datacenter comprising a fixed static set of Spine switches.\",\n \"Title: MRCP-RM: A Technique for Resource Allocation and Scheduling of MapReduce Jobs with Deadlines\\nYear: 2017\\n\\nAbstract: Resource allocation and scheduling on clouds are required to harness the power of the underlying resource pool such that the service provider can meet the quality of service requirements of users, which are often captured in service level agreements (SLAs). This paper focuses on resource allocation and scheduling on clouds and clusters that process MapReduce jobs with SLAs. The resource allocation and scheduling problem is modelled as an optimization problem using constraint programming, and a novel MapReduce Constraint Programming based Resource Management algorithm (MRCP-RM) is devised that can effectively process an open stream of MapReduce jobs where each job is characterized by an SLA comprising an earliest start time, a required execution time, and an end-to-end deadline. A detailed performance evaluation of MRCP-RM is conducted for an open system subjected to a stream of job arrivals using both simulation and experimentation on a real system. The experiments on a real system are performed on a Hadoop cluster (deployed on Amazon EC2) that runs our new Hadoop Constraint Programming based Resource Management algorithm (HCP-RM) that incorporates a technique for handling data locality. The results of the performance evaluation demonstrate the effectiveness of MRCP-RM/HCP-RM in generating a schedule that leads to a low proportion of jobs missing their deadlines (P) and also provide insights into system behaviour and performance. In the simulation experiments, it is observed that MRCP-RM achieves on average an 82 percent lower P compared to a technique from the existing literature when processing a synthetic workload from Facebook. Furthermore, in the experiments performed on a Hadoop cluster deployed on Amazon EC2, it is observed that HCP-RM achieved on average a 63 percent lower P compared to an EDF-Scheduler for a wide variety of workload and system parameters experimented with.\",\n \"Title: Energy Aware Resource Management for MapReduce Jobs with Service Level Agreements in Cloud Data Centers\\nYear: 2016\\n\\nAbstract: Clouds which continue to garner interest from practitioners in industry and academia require effective energy aware resource managers to leverage processing power of underlying resources while minimizing energy consumption in global data centers. We devise a novel Energy Aware MapReduce Resource Manager for an open system, called EAMR-RM, that can effectively perform matchmaking and scheduling of MapReduce jobs each of which is characterized by a Service Level Agreement (SLA) for performance that includes a client specified execution time and a deadline such that energy consumption is minimized. Results of the discrete event simulation-based performance analysis demonstrate that the proposed technique can effectively satisfy SLA requirements while achieving up to a 45% reduction in energy consumption compared to approaches which do not consider energy in resource management decisions.\",\n \"Title: A Greedy Data Association Technique for Multiple Object Tracking\\nYear: 2017\\n\\nAbstract: With recent advancements in complex image analysis algorithms and global optimization techniques, the qualitative performance of Multiple Object Tracking (MOT) has improved significantly, at the cost of slow processing speed. With a focus on high-speed performance, in this paper, we propose a fast data association technique for tracking multiple objects by using Tracking-by-Detection paradigm. Followed by a pre-processing stage of creating reliable tracklets from given detection responses, we propose a threshold-based greedy algorithm that iteratively finds a locally optimum solution with significantly low computational overhead. Experiments conducted on two benchmark datasets show that our method is able to achieve qualitative results comparable to the existing state-of-the-art algorithms with an advantage of 50-600 times faster processing speed.\",\n \"Title: Techniques for Handling Error in User-estimated Execution Times During Resource Management on Systems Processing MapReduce Jobs.\\nYear: 2017\\n\\nAbstract: In our previous work, we described a resource allocation and scheduling technique for processing an open stream of MapReduce jobs with SLAs (characterized by an earliest start time, an execution time, and a deadline) called the Hadoop Constraint Programming based Resource Management technique (HCP-RM). Since the user-estimated job execution times are used to perform resource allocation and scheduling, error/inaccuracies in the execution times can hinder the ability of HCP-RM from making effective scheduling decisions, leading to a degradation in system performance. This paper focuses on improving the robustness of HCP-RM by introducing a mechanism to handle errors/inaccuracies in user estimates of job execution times that are submitted as part of the job's SLA. A Prescheduling Error Handling technique (PSEH) is devised to adjust the user-estimated execution times of the jobs to make them more accurate before they are used by the resource management algorithm. Results of experiments conducted on a Hadoop cluster deployed on Amazon EC2 demonstrate the effectiveness of the PSEH technique in improving system performance.\",\n \"Title: A Run Time Technique for Handling Error in User-Estimated Execution Times on Systems Processing MapReduce Jobs with Deadlines\\nYear: 2017\\n\\nAbstract: Effective management of resources on a cloud or cluster is crucial for achieving the quality of service requirements of users, which are typically captured in service level agreements (SLAs). This paper focuses on improving the robustness of resource allocation and scheduling techniques that process an open stream of MapReduce jobs with SLAs, by introducing techniques to handle errors/inaccuracies in user-estimated execution times that are submitted as part of the job's SLA. Inaccuracies in the estimates of task execution times can prevent the resource allocation and scheduling algorithm from making effective scheduling decisions, leading to a degradation in system performance. Techniques for handling error during runtime are presented to handle the situation where jobs have already started executing and their estimated execution times are inaccurate. A simulation-based performance evaluation of the error handling techniques is conducted, which demonstrates that the techniques are effective in improving system performance.\",\n \"Title: Priority Based Resource Scheduling Techniques for a Resource Constrained Stream Processing System.\\nYear: 2017\\n\\nAbstract: A multitenant Storm cluster runs multiple stream processing applications and uses the default Isolation Scheduler to schedule them. Isolation Scheduler assigns resources to topologies based on static resource configuration and does not provide any means for prioritizing topologies based on their varying business requirements. Thus, performance degradation, even complete starvation of topologies with high priority is possible when the cluster is resource constrained and comprises an inadequate number of resources. Two priority based resource scheduling techniques are proposed to overcome these problems. A performance analysis based on prototyping and measurements demonstrates the effectiveness of the proposed techniques.\",\n \"Title: Auto-Resource Provisioning for MapReduce-Based Multiple Object Tracking in Video.\\nYear: 2018\\n\\nAbstract: Use of complex image analysis and globally optimal techniques make the current Multiple Object Tracking (MOT) methods for video analysis computationally slow. An important issue in this context is meeting the specific latency requirement for a given application while processing large scale video data. This is especially important in emergency situations such as accidents, natural calamities, and terrorist attacks. This paper introduces a latency reducing MapReduce/Hadoop-based parallel solution for MOT. The system includes an Auto-Resource Provisioning technique for determining the number of Hadoop nodes required to process the MOT job within a user specified deadline. The estimated number of nodes are then provisioned by the system and the MOT application is executed on the Hadoop cluster comprising the desired number of nodes. A prototype is built using the AWS EC2 cloud. A performance analysis is performed using measurements made on the prototype and insights gained into system behavior and performance are presented.\",\n \"Title: Mapreduce-Based Techniques For Multiple Object Tracking In Video Analytics\\nYear: 2017\\n\\nAbstract: Multiple Object Tracking (MOT) has been deployed effectively in various applications including automated video surveillance, self-driving vehicles, robotics, and medical imaging. Despite improvements in the qualitative performance (accuracy) of the existing state-of-the-art MOT methods through complex image analysis and global optimization techniques, a high computational cost is still a performance limitation. This paper focuses on achieving a high computational speed and proposes three parallel MOT techniques based on MapReduce. This paper introduces techniques that provide a parallel solution which effectively handles the challenges of time-dependencies among the various sections of the video file processed during MOT. Through performance analysis of a prototype deployed on the Amazon EC2 cloud, this paper shows that the proposed techniques provide a scalable solution for parallelizing the MOT methods and achieves an efficiency and speedup of up to 77% and 17 respectively, for a large video file, on a 20 node Hadoop cluster.\",\n \"Title: Complex Event Recognition Notification Methodology for Uncertain IoT Systems Based on Micro-Service Architecture\\nYear: 2018\\n\\nAbstract: One of the main purposes of the Internet of Things (IoT) systems is to provide information on the observed physical system and to notify when a certain observed complex event occurs in the system. The biggest challenge of the IoT systems is that the systems collect a massive amount of uncertain data from diverse IoT devices, where the devices are connected through the internet. In addition to that, some events are inferred from other events and uncertainty is propagated from parent events to the inferred events, which additionally contributes to overall system uncertainty. The observed complex events are a complex relationship of primitive events that are produced by IoT devices and collected in IoT system. There were a couple of attempts to quantify the system uncertainty by estimating the likelihood of the occurrence of events of interest while taking into account the uncertain data and uncertain parameters of the model of the physical system with rule-based complex event processing and/or Bayesian network. These methods were implemented as stand-alone software solutions that are unable to scale under heavy loads of incoming events. This paper proposes a micro-service based notification methodology that uses complex event recognition to handle the IoT system uncertainty.\",\n \"Title: A Mobile Complex Event Processing System for Remote Patient Monitoring\\nYear: 2018\\n\\nAbstract: Complex Event Processing (CEP) is widely used for Remote Patient Monitoring (RPM). However, the state-of-the-art techniques use a centralized server to receive health sensor streams and detect complex events. This paper introduces an Internet of Things (IoT) based CEP approach that uses a mobile device on the edge and a remote IoT Hospital Server (IHS) deployed on the cloud. The prototype implementation of the system uses an open-source Siddhi CEP engine on the mobile device and an open-source Web Services Oxygen (WSO2) IoT Server on the IHS. In this architecture, complete complex event detection is performed on the edge and the complex event streams are sent to the hospital server using the Message Queuing Telemetry Transport (MQTT) protocol. The MQTT broker forwards complex event streams to an event listener service running on the hospital server that notifies the hospital staff. Advantages of performing CEP on the edge include circumventing out-of-order delivery of various health sensor streams, avoiding queuing delays at the hospital server and reducing the user cost for data transfer between the mobile device and the hospital server. Also, this technique provides the ability to generate local alarms for the patient even when the mobile network connecting the device to the hospital server is unavailable.\",\n \"Title: A Fast-Iterative Data Association Technique For Multiple Object Tracking\\nYear: 2018\\n\\nAbstract: A massive amount of video data is recorded daily for forensic post analysis and computer vision applications. The analyses of this data often require multiple object tracking (MOT). Advancements in image analysis algorithms and global optimization techniques have improved the accuracy of MOT, often at the cost of slow processing speed which limits its applications only to small video datasets. With the focus on speed, a fast-iterative data association technique (FIDA) for MOT that uses a tracking-by-detection paradigm and finds a locally optimal solution with a low computational overhead is introduced. The performance analyses conducted on a set of benchmark video datasets show that the proposed technique is significantly faster (50-600 times) than the existing state-of-the-art techniques that produce a comparable tracking accuracy.\",\n \"Title: A priority based resource scheduling technique for multitenant storm clusters\\nYear: 2016\\n\\nAbstract: In this work in progress paper, we present our ongoing effort towards devising a priority based resource scheduling technique and framework for apache storm. Apache Storm is a popular distributed real time stream processing engine which has been widely adopted by key players in the industry including YAHOO and Twitter. An application running in storm is called a topology that is characterized by a Directed Acyclic Graph (DAG). To run multiple of such topologies in a storm cluster, storm provides with default, out of the box scheduler called Isolation Scheduler. Isolation Scheduler assigns resources to topologies based on static resource configuration and does not provide any means to prioritize topologies based on their varying business priority. As a result, performance degradation, even complete starvation of topologies with high business priority is possible when available cluster resources are insufficient. A priority based resource scheduling strategy is proposed in this paper to overcome this problem. A preliminary performance evaluation is performed to demonstrate effectiveness of the proposed scheduler over the default storm Isolation Scheduler.\",\n \"Title: A hybrid auto-scaling technique for clouds processing applications with service level agreements.\\nYear: 2017\\n\\nAbstract: This research focuses on the automatic provisioning of cloud resources by an intermediary enterprise. This enterprise provides a virtual private cloud for a single client enterprise by using resources from a public cloud. The intermediary cloud provider is controlled by a broker that uses techniques to dynamically control the number of resources used by the client enterprise. The research presents a hybrid auto-scaling technique based on a combination of a reactive approach and a proactive approach to scale resources based on user demand. The primary goal of this auto-scaling technique is to achieve a profit for the intermediary enterprise while maintaining a desired grade of service for the client enterprise. The second goal of the technique is to reduce costs for the single client enterprise. The technique supports both on-demand requests and requests with service level agreements (SLAs). This paper describes the auto-scaling algorithms associated with the hybrid technique and includes a discussion of system design and implementation experience for a prototype system. A detailed performance analysis based on simulations and measurements made based on the prototype is presented.\",\n \"Title: A resource management technique for processing deadline-constrained multi-stage workflows.\\nYear: 2017\\n\\nAbstract: The use of cloud computing that provides resources on demand to various types of users, including enterprises as well as engineering and scientific institutions, is growing rapidly. An effective resource management middleware is necessary to harness the power of the underlying distributed hardware in a cloud. Two of the key operations provided by a resource manager are resource allocation (matchmaking) and scheduling. This paper concerns the problem of matchmaking and scheduling an open stream of multi-stage jobs (or workflows) with Service Level Agreements (SLAs) on a cloud or cluster. Multi-stage jobs require service from multiple system resources and are characterized by multiple phases of execution. This paper presents a resource allocation and scheduling technique called RM-DCWF: Resource Management Technique for Deadline-constrained Workflows that can efficiently matchmake and schedule an open stream of multi-stage jobs with SLAs, where each SLA is characterized by an earliest start time, an execution time, and a deadline. A rigorous simulation-based performance evaluation of RM-DCWF is conducted using synthetic workloads derived from real scientific workflows. In addition, the impact of various system and workload parameters on system performance is investigated. The results of this performance evaluation demonstrate the effectiveness of RM-DCWF as captured in a low number of jobs missing their deadlines.\",\n \"Title: Data Driven Priority Scheduling on a Spark Streaming System\\nYear: 2019\\n\\nAbstract: Big data has become essential for businesses as it enables companies and organizations to gather insights from their data and use it to determine marketing opportunities, assist decision-making or even to find new business opportunities. Companies spend a great deal of effort collecting large amounts of data, which in some cases must be processed in real-time in order to capitalize on business opportunities. Predicting the expected input load at a given point in time can be very difficult and sometimes impossible. As a result, a great deal of effort is put into creating techniques to address varying input loads. A widely used approach is dynamic resource provisioning, but resource provisioners may not react in time to address the resource shortage which can result in increased processing latencies. This paper presents a priority scheduling technique that can be used in conjunction with dynamic and static resource provisioning. This approach allows users to assign a priority to input data items. The scheduler ensures that higher priority data items are given precedence over lower priority data items. This means that when resources become constrained the higher priority data items receive a greater share of resources and experience lower queueing delays in comparison to low priority items. A prototype for the data driven priority scheduler is implemented on the Spark Streaming system.\",\n \"Title: A Performance Driven Micro Services-Based Architecture/System for Analyzing Noisy IoT Data\\nYear: 2019\\n\\nAbstract: The Internet of Things (IoT) technology presents a complex and challenging paradigm where a huge amount of noisy raw sensor data is collected in order to observe and detect critical events occurring on the system, and generate alarms when required. The biggest challenge of the IoT systems is that the systems collect a massive amount of uncertain data from diverse IoT devices connected through the network. In addition, some events are inferred from other events and uncertainty is propagated from parent events to the inferred events, which additionally contributes to overall system uncertainty. The observed complex events are a complex relationship of primitive events that are produced by IoT devices and collected in IoT systems. A survey performed on existing prior arts on quantifying uncertainty for complex events concluded that proposed existing solutions are unable to scale under heavy loads of incoming data. This paper presents a micro-service based notification methodology that uses complex event recognition (both complex event processing and probabilistic programming) to handle IoT systems uncertainty. In addition, the paper analyzes and recommends existing big data platforms for processing complex events in IoT systems. The current focus of our work includes research and development of the optimized deadline-based and cost-effective resource allocation algorithm in Apache Spark for Uncertain IoT Notification systems.\",\n \"Title: AParallel Processing Technique for Extracting and Storing User Specified Data\\nYear: 2021\\n\\nAbstract: Users are often interested in a specific type of data (preferences) available from a large volume of data collected on the system. An efficient and effective system that can only store the user preferred data from the large raw data set helps the users to search for relevant information on time. The motivation behind this paper is to devise such a technique. The technique uses machine learning as ...\",\n \"Title: A Technique for Extracting User Specified Information from Streaming Data\\nYear: 2021\\n\\nAbstract: Users are often interested in a specific type of data (user-preferred data) from large volumes of data streaming into the system in real-time. An efficient system that only stores user-preferred data from these data can reduce storage space by storing only the user-preferred data and discarding the remaining data. It also reduces the search latency which allows the users to search for relevant inf...\",\n \"Title: Boolean Logical Operator Driven Selective Data Filtering For Large Datasets\\nYear: 2022\\n\\nAbstract: Specific users of a system processing large data sets are often interested in only a small subset of the large volumes of available data. This paper presents research on a parallel processing based data filtering technique that filters out and stores only the subset of data that is of interest to a given user. A user’s preferences reflecting her/his interest are captured in a set of keywords or phrases which may be used in conjunction with Boolean operators. An Apache Spark based prototype is built and deployed on an Amazon EC2 cloud to demonstrate the viability of the approach and to analyze the performance of the proposed technique.\",\n \"Title: Methods for Transferring Data from a Compute to a Storage Cloud\\nYear: 2022\\n\\nAbstract: This research, done in collaboration with our industrial partner TELUS, concerns systems that use different platforms for the compute and storage infrastructures thus requiring data transfers between the two platforms. This paper focuses on four different data transfer techniques and analyzes their performance. An architectural framework and a proof-of-concept prototype are described and the analysis of the performance of the data transfer techniques are presented. The performance results described in this paper provide insights into system behavior and the performance of the different data transfer techniques.\",\n \"Title: SCN-DRL: Scheduler for large-scale Critical Notification applications based on Deep Reinforcement Learning\\nYear: 2022\\n\\nAbstract: A multi-objective Scheduling approach for large-scale microservice Critical Notification system applications (SCN-DRL) based on Deep Reinforcement Learning is presented. This paper addresses optimization for three objectives: cloud service cost, cloud resource utilization, and system notification deadline. Recent advances in the deep reinforcement learning field inspired us to research how to build a solution that learns to manage the cloud container’s resources directly from experience. SCN-DRL is an example solution that translates the containerized microservice cloud cluster scheduling problem into a learning problem. To the best of our knowledge, this is the first work dealing with multi-optimization objectives for critical microservice notification applications using deep reinforcement learning, where the notification load is variable and depends on the results of the other previously prior processed microservice. Our initial results show that SCNDRL performs better than state-of-the-art heuristics and adapts to different workload conditions without a noticeable drop in performance.\",\n \"Title: Multi-objective optimization for cloud provisioning: A case study in large-scale microservice notification applications\\nYear: 2022\\n\\nAbstract: An approach to optimizing a large-scale microservice deployment for a critical notification system is presented. This paper addresses optimization for three objectives: cloud service cost, cloud resource utilization of CPU, RAM and storage, and meeting the system notification deadlines. To the best of our knowledge, this is the first work dealing with multi-objective optimization for microservice notification applications where the notification load is variable and depends on other priorly executed microservice in request processes. Furthermore, best of our knowledge, this is the first work that is based on multi-objective optimization, analyzing and proposing a Pareto front and optimal list from preselected VM candidates. First, the paper formulates multi-objective optimization problems for microservice-based large-scale notification system applications and provides the mathematical deployment model. Then, based on the expected workload and required multi-objective criteria, the paper proposes a set of algorithms that provide the Pareto front optimal solution for preselecting a Cloud Service provider’s VM type. In the end, the paper presents a case study that demonstrates the use of the proposed technique.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":101,"string":"101"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":81,"string":"81"}}},{"rowIdx":82,"cells":{"question_id":{"kind":"string","value":"Ferat Sahin"},"question":{"kind":"string","value":"Generate an abstract for the title \"360° view camera based visual assistive technology for contextual scene information.\" using the following items: 1. Visually impaired aid\n2. 360° view camera\n3. Deep learning\n4. Classification accuracy\n5. Contextual information"},"answer":{"kind":"string","value":"In this paper, a system to aid the visually impaired by providing contextual information of the surroundings using 360° view camera combined with deep learning is proposed. The system uses a 360° view camera with a mobile device to capture surrounding scene information and provide contextual information to the user in the form of audio. The scene information from the spherical camera feed is classified by identifying objects that contain contextual information of the scene. That is achieved using convolutional neural networks (CNN) for classification by leveraging CNN transfer learning properties using the pre-trained VGG-19 network. There are two challenges related to this paper, a classification and a segmentation challenge. As an initial prototype, we have experimented with general classes such restaurants, coffee shops and street signs. We have achieved a 92.8% classification accuracy in this paper."},"correct_answer":{"kind":"string","value":"In this paper, a system to aid the visually impaired by providing contextual information of the surroundings using 360° view camera combined with deep learning is proposed. The system uses a 360° view camera with a mobile device to capture surrounding scene information and provide contextual information to the user in the form of audio. The scene information from the spherical camera feed is classified by identifying objects that contain contextual information of the scene. That is achieved using convolutional neural networks (CNN) for classification by leveraging CNN transfer learning properties using the pre-trained VGG-19 network. There are two challenges related to this paper, a classification and a segmentation challenge. As an initial prototype, we have experimented with general classes such restaurants, coffee shops and street signs. We have achieved a 92.8% classification accuracy in this paper."},"documents":{"kind":"list like","value":["Title: An artificial immune system approach to mobile sensor networks and mine detection\nYear: 2004\n\nAbstract: Abstract - The human immune system and ifs ability to continually develop and learn has been studiedfor many years. Its capacity to recognize its owas those thatpose a threat to the body’s homeostasis (non-se@ has lead to the creation of many algorithms that try to mimic this behavior. One of these algorithms is the Artificial Immune System (AIS). The foundation of AIS depends on the existence of both sensor and communication ranges (assumed circles) with which a single agent can collect and convey information to other agents within the range. It is the purpose of this paper to present a solution to the mine detection problem using cooperative mobile robots equipped with sensory and communication capabilities which allow the AIS approach to be utilized. Keywords: Artificial Immune System, Cooperative","Title: Pattern recognition with surface EMG signal based wavelet transformation.\nYear: 2012\n\nAbstract: EMG based input device is a natural means of human computer interface (HCI) because the electrical activity induced by the human's arm muscle movements can be interpreted and transformed into computer's control commands. In this paper, we describe an approach for classifying electromyography (EMG) signals using a multilayer perceptron neural network (MLP) and Bayesian classifier (BC) with the wavelet transformation technique for feature selection to discriminate 6 classes of motions to control a mouse. Wavelet Transformation (WT) was applied to raw EMG data and in order to decrease the dimension of the feature sets, principle component analysis (PCA) and sequential forward selection (SFS) were utilized.","Title: Darwinian Particle Swarm Optimization\nYear: 2005\n\nAbstract: Particle Swarm Optimization (PSO), an evolutionary algorithm for optimization is extended to determine if natural selection, or survival-of-the- fittest, can enhance the ability of the PSO algorithm to escape from local op- tima. To simulate selection, many simultaneous, parallel PSO algorithms, each one a swarm, operate on a test problem. Simple rules are developed to imple- ment selection. The ability of this so-called Darwinian PSO to escape local op- tima is evaluated by comparing a single swarm and a similar set of swarms, dif- fering primarily in the absence of the selection mechanism, operating on the same test problem. The selection process is shown to be capable of evolving the best type of particle velocity control, which is a problem specific design choice of the PSO algorithm.","Title: An application of human robot interaction: development of a ping-pong playing robotic arm.\nYear: 2005\n\nAbstract: This paper describes the design and development of a ping-pong robotic arm as an application of robotic vision. Displaced frame difference (DFD) is utilized to segment the ball motion from background motion. 3-D ball tracking using parametric calibration of single CCD camera is explained. This visual information is temporally updated and further employed to guide a robot arm to hit the ball at a specified location. The results signify the system development based on single camera tracking. System latency is measured as a function of the camera interface, processor architecture, and robot motion. Various hardware and software parameters that influence the real time system performance are also discussed.","Title: Structural Learning Of Bayesian Networks From Complete Data Using The Scatter Search Documents\nYear: 2004\n\nAbstract: Bayesian Networks are directed acyclic graphs that model the dependency relationships between variables of interest. These networks are characterized by the structure of the network and the conditional probabilities that specify the dependencies that exist between the variables. In this paper, the Scatter Search optimization algorithm is utilized in learning the structure of the Bayesian network from complete data. This involves a heuristic search for the best network structure that maximizes a scoring function given a database of cases. The scatter search algorithm is implemented on a database of cases sampled from known networks in order to test the accuracy of the structural learning. Empirical results from the implementations are presented in the paper.","Title: Block Matching with Particle Swarm Optimization for Motion Estimation\nYear: 2013\n\nAbstract: Block matching algorithms successfully reduce the computational load of the motion estimation. Block based motion estimation algorithms rely on block matching of the macro blocks defined in the search windows. In this paper, particle swarm optimization (PSO) is applied on block-matching problem. Particle swarm optimization is a computationally efficient iterative search algorithm that finds the best matching block between two consecutive frames. Finding the moving block in the image sequence requires a minimization algorithm. Using particle swarm optimization, the computational cost of the block matching is aimed to decrease. Particle swarm optimization is a heuristic algorithm and necessarily dependent on the selections of the parameters assigned. In our case, the particle swarm algorithm is designed to work on a small subset of the population of blocks. The position of a macro block in the estimated image can be revealed by the motion vectors generated by the particle swarm optimized block.","Title: Cooperation of decision-theoretic agents in the context of multi-agent systems.\nYear: 2003\n\nAbstract: Multi-agen: based solutions to problems, whether they are software agents or physical robots, are attractive because they are robust and scalable. Fundamental aspects of designing multi-agent systems involve modeling the intelligence of the agents and modeling their interactions. The intelligences of agents modeled here are encoded in Bayesian representa:ions a/ their world. The agents interact only by observing others and moving in such a way so as to probabilistically maximize their intemalizedgoal or utility. Using this multi- agentfiamework, a three agent herding is explored.","Title: Groundscouts: Architecture For A Modular Micro Robotic Platform For Swarm Intelligence And Cooperative Robotics\nYear: 2004\n\nAbstract: This paper presents architecture for a modular micro robotic platform for swarm intelligence and cooperative robotics research and applications. In a swarm the value of an individual is negligible since the goal of the swarm is essential. Thus, the agents (robots) need to be small, low cost, and cooperative. GroundScouts are designed based on these conditions. The proposed architecture slices a robot into abstract modules such as locomotion, control, sensors, communication, and actuation. Any mobile robot can be constructed by combining these abstract modules for a specific application. A modular embedded micro-OS with dynamic task uploading and multi-tasking abilities is developed in order to create better interface between robots and the command center and among the robots. The dynamic task uploading allows the robots change their behaviors in runtime. Thus, the robots can work in swarm, master-slave, or hybrid mode and possibly be used in other applications such as mobile sensor networks, remote sensing, and plant monitoring.","Title: Cognitive Maps In Swarm Robots For The Mine Detection Application\nYear: 2003\n\nAbstract: Navigation based on cognition is seen in many instances in the animal community. Maps are very useful for navigation in unknown and complex environments. User defined and preinstalled maps can be very useful in navigation in complex environments, while adoptively built maps become very essential in unknown environments. Intelligence is bestowed in the effective utilization of data to produce decisions. In the case of navigation, intelligence is seen when information collected en-route from a source to a destination is used judiciously in reaching the destination. In this paper we deal with the foraging of a piece of terrain as a process of navigation. The application here is mine detection. Mines are placed over afield at unknown locations and swarm intelligence based agents are deployed for demining them. The efficiency of the demining process is measured in terms of the quickness with which they can clear the mines and the assurance that the minefield is clear of all of the mines at the end of the process. Simulation results acknowledging the performance under different working conditions of the swarm robots are presented In an endeavor to substantiate our claims in simulation we decided to build swarm robots performing the task on an artificially developed environment.","Title: Fault diagnosis for airplane engines using Bayesian networks and distributed particle swarm optimization\nYear: 2007\n\nAbstract: This paper presents a fault diagnosis system for airplane engines using Bayesian networks (BN) and distributed particle swarm optimization (PSO). The PSO is inherently parallel, works for large domains and does not trap into local maxima. We implemented the algorithm on a computer cluster with 48 processors using message passing interface (MPI) in Linux. Our implementation has the advantages of being general, robust, and scalable. Unlike existing BN-based fault diagnosis methods, neither expert knowledge nor node ordering is necessary prior to the Bayesian Network discovery. The raw datasets obtained from airplane engines during actual flights are preprocessed using equal frequency binning histogram and used to generate Bayesian networks fault diagnosis for the engines. We studied the performance of the distributed PSO algorithm and generated a BN that can detect faults in the test data successfully.","Title: New classification techniques for electroencephalogram (EEG) signals and a real-time EEG control of a robot.\nYear: 2013\n\nAbstract: This paper studies the state-of-the-art classification techniques for electroencephalogram (EEG) signals. Fuzzy Functions Support Vector Classifier, Improved Fuzzy Functions Support Vector Classifier and a novel technique that has been designed by utilizing Particle Swarm Optimization and Radial Basis Function Networks (PSO-RBFN) have been studied. The classification performances of the techniques are compared on standard EEG datasets that are publicly available and used by brain–computer interface (BCI) researchers. In addition to the standard EEG datasets, the proposed classifier is also tested on non-EEG datasets for thorough comparison. Within the scope of this study, several data clustering algorithms such as Fuzzy C-means, K-means and PSO clustering algorithms are studied and their clustering performances on the same datasets are compared. The results show that PSO-RBFN might reach the classification performance of state-of-the art classifiers and might be a better alternative technique in the classification of EEG signals for real-time application. This has been demonstrated by implementing the proposed classifier in a real-time BCI application for a mobile robot control.","Title: Lossless compression of color palette images with one-dimensional techniques\nYear: 2006\n\nAbstract: Palette images are widely used on the World Wide Web (WWW) and in game-cartridge applications. Many images used on the WWW are stored and transmitted after they are compressed losslessly with the standard graphics interchange format (GIF), or portable network graphics (PNG). Well-known 2-D compression schemes, such as JPEG-LS and JPEG-2000, fail to yield better compression than GIF or PNG due to the fact that the pixel values represent indices that point to color values in a look-up table. To improve the compression performance of JPEG-LS and JPEG-2000 techniques, several researchers have proposed various reindexing algorithms. We investigate various compression techniques for color palette images. We propose a new technique comprised of a traveling salesman problem (TSP)-based reindexing scheme, Burrows-Wheeler transformation, and inversion ranks. We show that the proposed technique yields better compression gain on average than all the other 1-D compressors and the reindexing schemes that utilize JPEG-LS or JPEG-2000. (C) 2006 SPIE and IS&T.","Title: Uniform Cellular Automata Linear Rules for Edge Detection\nYear: 2013\n\nAbstract: In this paper we discuss the application of two-dimensional linear cellular automata rules to the problems of edge detection in monochromatic images. We proposed an efficient and simple method of edge detection based on uniform cellular automata transition matrix representation. We investigate of cellular automata linear rules for edge detection by using matrix representation, in some cases they are strong and some other rules are not in fact useful for practical edge detection. All rules give computationally effective result since the computation mechanism consist only matrix multiplication. Finally, we present some results of the proposed linear rules for edge detection and compare with some classical results.","Title: An XML based system of systems discrete event simulation communications framework\nYear: 2009\n\nAbstract: Simulations play an important role in complex systems development. In a System of Systems (SoS) consisting of heterogeneous independent systems (as is the case with cooperative robotics, for example), effective communication among the systems is essential. This paper extends the application of Extensible Markup Language (XML) as a method of wrapping data without imposing other restrictions on the systems in an SoS. The effort to model and implement XML communication among members of an SoS is based on Discrete Event Specification (DEVS) and uses DEVSJAVA software as the simulator. An XML based SoS simulation framework is presented by a robust threat detection scenario involving multiple heterogeneous systems working cooperatively to accomplish the goal. This framework will also support agent-in-the-loop simulations using real time DEVS modeling in future work.","Title: Autonomous Navigation Based On A Q-Learning Algorithm For A Robot In A Real Environment\nYear: 2008\n\nAbstract: This paper explores autonomous navigation and obstacle avoidance techniques based on Q-learning for a mobile robot in a real environment. The implemented algorithm focuses on simplicity and efficiency. The learning process takes place in both simulation and real world allowing the combination of a longer learning time in the simulator with a more accurate knowledge from the real world. After learning is completed in simulation and in the real world the robot was able to navigate without hitting obstacles and able to generate control law for complex situations such as corners and small objects.","Title: Decision Theoretic Agent Design For Personal Rapid Transit Systems\nYear: 2007\n\nAbstract: This paper details a learning decision-theoretic intelligent agent designed to solve the problem of guiding vehicles in the context of Personal Rapid Transit (PRT). The intelligent agents are designed using Bayesian Decision Networks. The agents are designed to utilize the known methods of machine learning with Bayesian Networks (BN): parameter learning and structure learning. In addition, a new method of machine learning with BNs, termed utility learning in this paper, is introduced. BN software for Matlab is used to realize the proposed agent. Additional software is written to simulate the PRT problem using various intelligent agents that utilize one or more learning methods.","Title: A Discrete Event Xml Based System Of Systems Hardware-In-The-Loop Simulation For Robust Threat Detection\nYear: 2009\n\nAbstract: In a system of systems (SoS) consisting of heterogeneous independently operable systems, successfully sending, receiving, and understanding data is necessary to achieve interoperation among the systems. Extensible Markup Language (XML) is applied to wrap the data in a way that is commonly understood in the SoS while the asynchronous nature of the interactions among systems is viewed as an event driven system. Discrete event specification (DEVS) formalism is used to describe the models composing the SoS. Simulation provides a means to examine and analyze systems and their interactions as well as how a new system effects the SoS but can hide issues that arise during final implementation. Hardware-in-the-loop (HIL) simulation provides a bridge between simulation and implementation in order to reduce build cost and more readily verify a system's desired performance. A Groundscout robot is used as a real system in the simulation of a robust threat detection scenario.","Title: In-Vivo Fault Analysis and Real-Time Fault Prediction for RF Generators Using State-of-the-Art Classifiers\nYear: 2013\n\nAbstract: In this paper we apply various machine learning techniques for fault detection of RF (Radio Frequency) Power Generators. Fast Fourier Transform features are used in our analysis for all experiments. Radial Basis Function Networks (RBF) is used to build a two class classifier to differentiate between normal and one fault condition. We apply three one class classifiers to model the normal operating conditions. The data is obtained from five different generators of the same model type.","Title: Robust Recruitment Near The Edge Of Chaos And An Application To Mine Sweeping\nYear: 2003\n\nAbstract: The field of robotics is in rapid development. As robots become cheaper to build, new applications involving many robot systems can be envisioned One reason for using many robots is to achieve robustness. Having many robots, however, does not ensure robustness. A control strategy and robot behaviors must be engineered to incorporate robustness into the system. Swarm intelligence based approaches are popular for developing optimal and robust control strategies for systems of robots. Here we analyze the behavior of a swarm of robots modeled after a swarm of ants, where tasks are spatially distributed in the environment and robots/ants are recruited through short-range recruitment. For ants that move probabilistically in response to the short range signal and who adjust their probabilities such that they are near a phase change boundary, or edge-of-chaos, in the mean field analysis of their motions, we find a significant improvement in the robustness of the system.","Title: FPGA implementation of particle swarm optimization for Bayesian network learning\nYear: 2013\n\nAbstract: Using a Bayesian network (BN) learned from data can aid in diagnosing and predicting failures within a system while achieving other capabilities such as the monitoring of a system. However, learning a BN requires computationally intensive processes. This makes BN learning a candidate for acceleration using reconfigurable hardware such as field-programmable gate arrays (FPGAs). We present a FPGA-based implementation of BN learning using particle-swarm optimization (PSO). This design thus occupies the intersection of three areas: reconfigurable computing, BN learning, and PSO. There is significant prior work in each of these three areas. Indeed, there are examples of prior work in each pair among the three. However, the present work is the first to study the combination of all three. As a baseline, we use a prior software implementation of BN learning using PSO. We compare this to our FPGA-based implementation to study trade-offs in terms of performance and cost. Both designs use a master-slave topology and floating-point calculations for the fitness function. The performance of the FPGA-based version is limited not by the fitness function, but rather by the construction of conditional probability tables (CPTs). The CPT construction only requires integer calculations. We exploit this difference by separating these two functions into separate clock domains. The FPGA-based solution achieves about 2.6 times the number of fitness evaluations per second per slave compared to the software implementation.","Title: Application Of Soft Computing Techniques To Estimate The Effective Young'S Modulus Of Thin Film Materials\nYear: 2007\n\nAbstract: This research aims at characterizing and predicting the Young's Modulus of thin film materials that are utilized in Microelectromechanical systems (MEMS). Recent studies indicate that the mechanical properties such as Young's Modulus of thin films are significantly different from the bulk values. Due to the lack of proper understanding of the physics in the micro-scale domain the state-of-art estimation techniques are unreliable and often unfit for use for predicating the mechanical behavior of slight modifications of existing designs as well as new designs. This disadvantage limits the MEMS designers to physical prototyping which is cost ineffective and time consuming. As a result there is an immediate need for alternative techniques that can learn the complex relationship between the various parameters and predict the effective Young's Modulus of the thin films materials. The proposed technique attempts to solve this problem using empirical estimation techniques that utilize soft computing techniques for the estimation as well as the prediction of the effective Young's Modulus. As a proof of concept, effective Young's Modulus of Aluminum and TetrathylOrthoSilicate (TEOS) thin films were computed by fabricating and analyzing self-deformed micromachined bilayer cantilevers. In the estimation phase, 2D search and micro Genetic algorithm were studied and in the prediction phase, back propagation based Neural networks and One Dimensional Radial Basis Function Networks (1D-RBFN) were studied. The performance of all combinations of these soft computing techniques is studied. Based on the results, we conclude that performance of the soft computing techniques is superior to the existing methods. In addition, the effective values generated using this methodology is comparable to the values reported in the literature. Given a finite number of data samples, the combination of 1D-RBFN (prediction phase) and GA (estimation phase) presented the best results. Due to these advantages, this methodology is foreseen to be an essential tool for developing accurate models that can estimate the mechanical behavior of thin films.","Title: Application of Particle Swarm Optimization for Traveling Salesman Problem to lossless compression of color palette images.\nYear: 2008\n\nAbstract: This paper investigates optimal color indexing for the compression of color palette images. This work enhances the recent traveling salesman problem (TSP) based re-indexing technique with particle swarm optimization (PSO). In this work, color re-indexing is done by solving the problem as a TSP using PSO. The proposed technique, yields better compression gains than the recent work that used a cross entropy (CE) based TSP for re-indexing.","Title: A survey on feature selection methods\nYear: 2014\n\nAbstract: Plenty of feature selection methods are available in literature due to the availability of data with hundreds of variables leading to data with very high dimension. Feature selection methods provides us a way of reducing computation time, improving prediction performance, and a better understanding of the data in machine learning or pattern recognition applications. In this paper we provide an overview of some of the methods present in literature. The objective is to provide a generic introduction to variable elimination which can be applied to a wide array of machine learning problems. We focus on Filter, Wrapper and Embedded methods. We also apply some of the feature selection techniques on standard datasets to demonstrate the applicability of feature selection techniques.","Title: Design of Intelligent Agents for Personal Rapid Transit\nYear: 2007\n\nAbstract: This paper presents machine learning concepts to successfully implement an intelligent agent solution to the problem of autonomous control of Personal Rapid Transit (PRT) vehicles. The PRTs can operate independently and together as a whole system. Thus, they can be considered as a system of systems. By developing a set of rules for the vehicles to follow, the various parts of a Bayesian Network (BN), its nodes, parameters, structure and utility function are determined. The variables in the network are generated from the sensor data of the PRT vehicles. Using the overall system goals, a utility function can be devised that will select the best action for an agent to take. Simulation results show that this methodology is useful for \"rapid prototyping\" a decision theoretic agent. The gap between the intelligent agent and rule based agent performance for the collision metrics suggests that more research is needed to develop a systematic method of creating utility functions to meet system goals.","Title: Application Of Swarm Intelligence To The Mine Detection Problem\nYear: 2004\n\nAbstract: This paper will highlight the important points of swarm intelligence, more specifically the Ant Algorithm, and illustrate how it can be applied to a real time mine defection problem. The algorithm will be applied using GroundScouts, a modular micro robot that was designed for cooperative robotics applications. An Adaptive Time Division Multiple Access (ATDMA) communication scheme will also be presented that changes the behavior of the network according to the number of robots on the network. This maximizes the efficiency of the communication between the robots. The results will show that the real time implementation of the algorithm is successful.","Title: A comparison of chatter attenuation techniques applied to a twin rotor system\nYear: 2014\n\nAbstract: The twin rotor MIMO system (TRMS) is a helicopter-like system that is restricted to two degrees of freedom, pitch and yaw. It is a complicated nonlinear, coupled, MIMO system used for the verification of control methods and observers. This paper compares the ability of three adaptive sliding mode controllers (SMC) to suppress chattering. Once the design is complete the controllers are implemented in simulation and experimentally. The performance of the controllers are compared against a PID controller and other controllers in the literature. The ability of the sliding mode controllers (SMC) to suppress chattering is also be explored.","Title: Embedded one-class classification on RF generator using Mixture of Gaussians\nYear: 2014\n\nAbstract: In this paper we apply a specific machine learning technique for classification of normal and not-normal operation of RF (Radio Frequency) power generators. Pre-processing techniques using FFT and bandpower convert time-series system signatures into single feature vectors. These feature vectors are modeled using k-component Mixture of Gaussians (MoG) where components and corresponding parameters are learned using the Expectation Maximization (EM) algorithm. Data is obtained from three different generator models operating under normal and multiple different not-normal conditions. Exploration into algorithmic parameter effects is conducted and empirical evidence used to select sub-optimum parameters. Robust testing is reported to achieve a 3s classification accuracy of 95.91% for the targeted RF generator. Additionally, a custom C++ library is implemented to utilize the learned model for accurate classification of time-series data within an embedded environment such as a RF generator. The embedded implementation is reported to have a small storage footprint, reasonable memory consumption and overall fast execution time.","Title: Ant colony optimization based swarms: implementation for the mine detection application\nYear: 2004\n\nAbstract: Mine detection is a sensitive task confronting the battlefield strategists. There is an ever-increasing demand for proper and sophisticated resources for many issues involved in the task. Traditional practices still involve human force directly in executing the tasks in spite of the advances in technology for tools and implements for the operation [GAO, 2001]. The problem includes various facets inherently: two of the prominent issues are location of mines over a minefield and secondly removal of the mines once located [GAO, 2001]. These two issues are not totally independent as technology used for one can directly or indirectly affect the other. Developments in artificial intelligence, natural heuristics, computational optimization and robotics have endowed us with the ability to realize unmanned robots (or robot like vehicles) that work intelligently on a real time basis in attempting at the problem of mine detection. In this paper we focus on the algorithms developed using ant colony optimization based approaches to the mine detection application and its implementation on a real-time basis. We focus on certain optimization techniques that could be used for effective realization of the algorithm. Generic groundscout robots had been already built at the MABL, RIT [Sahin F. et al., 2003]. These robots have been used to demonstrate the implementation","Title: Generating and exploiting bayesian networks for fault diagnosis in airplane engines\nYear: 2006\n\nAbstract: Bayesian Networks has been proven to be successful too[ for fault diagnosis. There are a variety of approaches for learning the structure of Bayesian Networks from data. This learning problem has been proven to be NP-hard hence none of the approaches are exact when no prior knowledge about the domain of the variables exists. Our approach is based on searching the best network by using particle swarm optimization (PSO) technique. PSO is inherently parallel, works for large domains and does not trap into local maxima. This paper is an application of this technique to a real world problem; fault diagnosis of an airplane engine for oil related variables. It is implemented by our improved software written in C/C++ by using MPI on Linux. Our implementation has the advantages of being general, robust and scalable. Moreover neither expert knowledge, nor node ordering is necessary prior to the optimization. The datasets are generated by preprocessing oil related sensor readings of airplane engines taken during the approach phase of flights. Using this datasets and our software, we constructed Bayesian Networks of the oil related variables in an airplane engine for diagnostics and predictive purposes.","Title: A Discrete Event XML based Simulation Framework for System of Systems Architectures\nYear: 2007\n\nAbstract: System of systems (SoS) concept is essential in solving the issues in complex systems where there are heterogeneous independently operable systems. In order for these independent systems to establish an SoS, they need to understand each other through effective communication. Thus, there is a need for a common language which wraps the data that is sent and received from a system within an SoS. This paper presents the application of extensible markup language (XML) to represent data communicated among systems without underlying differences in hardware software of the individual systems. Moreover, since the operation of each system is asynchronous in nature, the entire SoS can be considered as an event driven system. This paper presents a simulation framework to simulate the structure of the systems in an event driven fashion and wraps the data with a common language. The DEVSJAVA software is used as the discrete event simulator. In addition, XML based encapsulation is created in the DEVSJAVA environment to in the SoS.","Title: A discrete event XML based system of systems simulation for robust threat detection and integration\nYear: 2008\n\nAbstract: In a system of systems (SoS) consisting of heterogeneous independently operable systems, effective communication among the systems is essential. These independent systems need to understand each other through effective communication in or order for them to establish a SoS. Thus, there is a need for a common language which wraps the data that is sent and received from a system within a SoS. This paper presents and extends the application of extensible markup language (XML) to represent data communicated among systems without underlying differences in hardware/software of the individual systems. Moreover, since the operation of each system is asynchronous in nature, the entire SoS can be considered as an event driven system. This paper extends an XML based SoS simulation framework to simulate a robust threat detection and integration problem. The DEVSJAVA software is used as the discrete event simulator. Finally, XML based encapsulation is created in the DEVSJAVA environment to create the common language for the heterogeneous systems in a SoS.","Title: A study of crossover operators and reference set sizes for scatter search in unconstrained function optimization\nYear: 2011\n\nAbstract: This paper explores different crossover operators and how they affect the Scatter Search (SS) algorithm in unconstrained function optimization. It also explores how the size of the reference set affects convergence and robustness. An introduction to Scatter Search is given along with the typical template. It follows with a thorough explanation of the specific implementation that is used. Two types of tests are designed: (1) what is the best fitness value that it can reach within a maximum number of fitness evaluations and (2) how fast it can converge to goal fitness. These tests are performed using different crossover operators and reference set sizes. Results are also compared apples to apples with a basic implementation of Particle Swarm Optimization (PSO). The results show that although PSO is quicker at converging, SS shows more robustness with higher overall success rates.","Title: Computing optimal snowplow route plans using Genetic Algorithms\nYear: 2011\n\nAbstract: The road network of a small town is represented by a directed graph. Road junctions are the vertices of this graph and each road segment (which has a length and a priority value) is represented by a directed edge. Priority values are numbers 1, 2, etc. with the assumption that 1 is the highest priority. We seek to compute an optimal route map that begins at a particular vertex (the depot) and covers all the edges at least once and returns to the start vertex. The parameters that we wish to minimize are: the total distance covered (thereby minimizing the deadhead miles), the number of u-turns and priority misplacements. In this paper, we propose a Genetic Algorithms-based solution to compute near-optimal route maps in such a graph. Specifically, we have developed a Java software application that generates route maps that minimize a linear combination of the three parameters. We have experimented with reasonably large graphs and obtained good solutions. These solutions are especially useful in snowplow routing for small towns, as plowing costs consume significant portions of the total municipal budgets of these communities. Most of the route planning is currently done manually and routes have evolved over time by experience. In these times of severe budget stress, route planning using our approach can help in performing this essential service in an efficient manner.","Title: Extraction of memory colors using Bayesian Networks\nYear: 2009\n\nAbstract: In this work, a region classification algorithm based on low-level features and probabilistic framework is proposed where skin, sky, and vegetation memory color classes are detected in digital images. A region's low-level features are extracted using a segmentation map of input image. Bayesian network (BN) is used to classify memory color regions for smart rendering in printing applications. Other applications of the proposed technique include image annotation, indexing, and content retrieval. The algorithm was tested on a large database of color images with 85% classification accuracy.","Title: A System of Systems approach to model an Artificial Immune System using Discrete Event Specification\nYear: 2009\n\nAbstract: An artificial immune system (AIS) is a biological inspiration of the human immune system and continues to emerge as a technique for a wide area of applications. This paper presents a model of AIS as it applies to a multi-agent formation problem, similar to predator and prey scenario. Successful multi-agent formations are discovered in conjunction with the artificial immune system's agents and their behaviors. The hierarchy of agents within the artificial immune system support; a system of systems (SoS) based development strategy. The AIS SoS model is implemented based on discrete event specification (DEVS) and simulated using the DEVSJAVA software framework. The resulting model and simulation demonstrates successfully created multi-agent formations of predator around a single prey.","Title: An XML based system of systems agent-in-the-loop simulation framework using discrete event simulation\nYear: 2009\n\nAbstract: This paper extends an XML based system of systems simulation framework using DEVS to support hardware-in-the-loop simulations for SoS. A system of systems approach enables the simulation and analysis of multiple complex, independent, and cooperative systems by concentrating on the data transferred among systems. This paper wraps information exchanged among heterogeneous systems in XML to enable receiving systems to correctly parse and interpret the information. A Groundscout robot is deployed as a real agent working cooperatively with virtual agents in a robotic swarm. The DEVS activity concept facilitates communication between the real system and virtual systems in the SoS. A robust threat detection example is provided. Initial performance metrics of the SoS are briefly discussed.","Title: A net-centric XML based system of systems architecture for human tracking\nYear: 2010\n\nAbstract: Human detection and tracking is a primary focus for visual surveillance systems. However, current systems for human tracking are often complex and require vast amounts of computing resources. A reduction in complexity of the overall tracking system can be achieved by using a System of Systems (SoS) architecture. Once formed, a SoS architecture must achieve desirable levels of interoperability and integration. Proposed in this paper is a human tracking system that uses a net-centric SoS architecture capable of detecting a human via video surveillance and subsequently providing coordinates for mobile robot tracking. This SoS architecture establishes integration and conceptual interoperability through the standardization of communication and data representation. Within the SoS, communication is accomplished using a client-server architecture while data is structured according to a custom XML framework. The resulting SoS is composed of decentralized independent systems inter-operating on heterogeneous platforms to achieve the ultimate goal of human tracking.","Title: Agent-in-the-loop simulation for testing swarm robots using an XML-based system of system framework in discrete-event simulation specification\nYear: 2011\n\nAbstract: This work builds upon our previous work, where a swarm robot called a Groundscout was tested for its emergent behavior(s) using a system of systems framework based on discrete-event simulation and XML-based hardware in the loop simulation (HIL). This paper presents performance optimizations, bug-fixes, and implementations of new features to further examine the benefits of using HIL simulations to develop and test swarm robots. In this work, the Groundscout's communications protocols were improved, a new obstacle-avoidance algorithm was added, and the environment and simulation engines have been either re-implemented or optimized for performance. Specifically for the obstacle-avoidance algorithm, the benefits of using HIL simulations, together with the principle of model continuity, are clearly demonstrated with testing experiments. Towards the eventual goal of creating simulations for testing emergent behaviors of much larger robot swarms, considerations that were learned are presented.","Title: In-vivo fault prediction for RF generators using variable elimination and state-of-the-art classifiers\nYear: 2012\n\nAbstract: In this paper we apply two variable elimination algorithms to data obtained from an RF (Radio Frequency) Power Generator Fault Mode for analysis. We use a two wrapper approach using Support Vector Machines (SVM) and Radial Basis Function Networks (RBF) to build an efficient classifier with variable elimination. Comparisons are made for both continuous and discrete datasets.","Title: Net-centric System of Systems framework for human detection\nYear: 2013\n\nAbstract: System of Systems (SoS) architectures have been used to conceptually define complex systems. However, very few SoS architectures have been physically realized to solve real-world problems. Proposed in this work is the full realization of a net-centric SoS architecture used to implement and integrate a complex system used to automate human detection from an image source. A SoS architecture was selected to implement the human detection system due to a SoS's ability to achieve high levels of interoperability. This high level of interoperability is feasible via standardization of communication and by structuring information to conform to a proposed XML framework. Additionally, each individual system within the SoS hierarchy is functionally decomposed based on sets defined services that each system requires and provides. Moreover, a new concept of a commonly implemented directory service is used to initialize system communication and automate SoS architecture discovery.","Title: Simultaneous localization and mapping using a micro-particle swarm optimization\nYear: 2015\n\nAbstract: Scan matching is a popular way of calculating a robot's position given range data corresponding to objects in the environment. This paper proposes a simultaneous localization and mapping algorithm that uses micro-particle swarm optimization as an alternative method to the traditional scan matching algorithms. The effectiveness of this algorithm is tested and compared to other popular simultaneous and localization algorithms.","Title: A framework for a real time intelligent and interactive Brain Computer Interface.\nYear: 2015\n\nAbstract: •A framework for a real time implementation of a Brain Computer Interface.•Implementation & comparison of different feature extraction methods and classifiers.•Accuracy & processing time comparison for detection of event related potentials-ERP.•An implementation of a prototype system using the proposed BCI framework.•Real time EEG data collection and classification of ERPs using Hex-O-Speller.","Title: Edge detection with fuzzy cellular automata transition function optimized by PSO\nYear: 2015\n\nAbstract: Fig. 2. Proposed method result of different rules for Im 1 ( Δ = 110 , ¿ = 0.62 ), (a) Original Image, (b) Ground Truth, (c) Rule 47, (d) Rule 170, (e) Rule 367, (f) Rule 510.Display Omitted This study is the application of 2D linear cellular automata (CA) rules with the help of fuzzy membership function to the problems of edge detection.An efficient and simple thresholding technique of edge detection based on CA transition rules optimized by Particle Swarm Optimization method (PSO) is proposed.Results of the proposed to the selected 22 images from the Berkeley Segmentation Dataset (BSDS) are presented.Comparison with some classical Sobel and Canny results is included.Baddeley Delta Metric (BDM) is used for the performance index to compare the results. In this paper we discuss the application of two-dimensional linear cellular automata (CA) rules with the help of fuzzy heuristic membership function to the problems of edge detection in image processing applications. We proposed an efficient and simple thresholding technique of edge detection based on fuzzy cellular automata transition rules optimized by Particle Swarm Optimization method (PSO). Finally, we present some results of the proposed linear rules for edge detection to the selected 22 images from the Berkeley Segmentation Dataset (BSDS) and compare with some classical Sobel and Canny results. Also, Baddeley Delta Metric (BDM) is used for the performance index to compare the results.","Title: Modeling and dynamic control for a hexapod robot\nYear: 2015\n\nAbstract: In the every expanding field of robotics, mobile robots come in a two primary variations: wheeled and legged. This paper will focus on the latter, specifically a hexapod with a circular body that has its six legs distributed axisymmetrically around the body. The core goal of the project discussed here is to allow the robot to dynamically change foot placement based on an input vector in addition to controlling the position and orientation of the body. Specific attention is also given to a simulation model that can mimic this control of the robot in a virtual environment. Having a high level of control enhances the robot's ability to move in a very smooth and purposeful manner.","Title: A system of systems analysis of a multi-probe SPM system\nYear: 2015\n\nAbstract: In this paper, we introduce a multi-probe Scanning Probe Microscopy (SPM) tool in the context of system of systems (SoS) concepts. The tool exhibits strong characteristics of SoS such as interoperability, integration and independency of each individual system. Each probe terminal constitutes an independent scanning system that can operate individually. The interoperability of the systems through signal exchange bring strong advantages and help users in order to design innovative applications that would not be easily achievable when a single system is used. As an independent system, each probe terminal includes its own controller and feedback mechanism for precise operation which is controlled by individual software running on control PCs. After introducing the overall system, we briefly mention one of the innovative real-world applications that we have been currently working on in an effort to show the strength of SoS engineering and filling the gap between theory and practice.","Title: Omnidirectional rule-based free gait utilizing restrictedness\nYear: 2015\n\nAbstract: Adaptable gaits are pivotal for allowing legged robots to navigate difficult terrain. One of the best gait styles to accomplish this goal is the rule-based free gait. First the forward and inverse kinematic solutions are solved for TigerBug, a circular hexapod. Then a rule based free gait is implemented on the circular hexapod in order to provide a platform for future rough terrain navigation.","Title: Dual flexible 7 DoF arm robot learns like a child to dance using Q-learning\nYear: 2015\n\nAbstract: Many attempts have been made by researchers and scholars to make people feel more conversant to robots. One such example is the dance performance of an Entertainment Robot. In most cases, the challenge to program dance motions for a robot and synchronize them has been too heavy. In addition, pre-programmed dance moves and synchronization information are useful only for a specific music track and are useless for any other. To solve these problems, we developed a new system that can make a robot learn dance moves according to the input music track. The system comprises of two main parts: the first is a beat extraction system for music track; and the second one is a system that learns dance motion for Baxter. In the first part, music track is analyzed using STFT and peak-to-peak time duration is computed. This gives the beats per minute (BPM) of the given music track. The second part takes the BPM and duration of track and feeds it to the developed Q-learning algorithm to make Baxter learn dance moves and synchronize dance motion to beat rate.","Title: A Framework For Intelligent Creation Of Edge Detection Filters\nYear: 2015\n\nAbstract: In this paper, we introduce a framework for a system which intelligently assigns an edge detection filter to an image based only on features taken from the image. The system has four parts, the training set which consists of an image and its edge image ground truth, feature extraction, training filter creation, and system training. A prototype system of this framework is given. In the system feature extraction is performed using a GIST methodology which extracts color, intensity, and orientation information as features. The set of image features are used as the input to a single hidden layer feed forward neural network trained using back propagation. The system trains against a set of linear Cellular Automata filters which are determined to best solve the edge image according to the Baddelay Delta Metric. This metric takes into account false positives and false negative error by scaling the errors relative to the perpendicular distance that they are off from the ground truth. The system was trained and tested against the images from the Berkeley Segmentation Database. The results from the testing indicate that the system performs better than standard methods in many cases but on the whole is only on par across a wide range of images.","Title: Real-Time American Sign Language Recognition System Using Surface EMG Signal\nYear: 2015\n\nAbstract: Sign Language Recognition (SLR) system is a method which allow deaf people to communicate with society. In this study, Real-Time Sign Language recognition system was proposed by using the surface Electromyography (sEMG). To this purpose, sEMG data acquired from subject right forearm for all twenty six American Sign Language gestures. Raw sEMG data was filtered, feature extracted and fed into classification. Support Vector Machine (SVM) with one vs. all approach was used for multi class classification. The experiment result of offline system is reaching a recognition rate of 91.% accuracy and real-time system has a recognition rate of 82.3% accuracy. The results of the proposed system shows that sEMG signal can be used for Real-Time SLR systems.","Title: Systemic health evaluation of RF generators using Gaussian mixture models.\nYear: 2016\n\nAbstract: We propose an application of specific machine learning techniques capable of evaluating systemic health of a Radio Frequency (RF) power generator. System signatures or fingerprints are collected from multivariate time-series data samples of sensor values under typical operational loads. These fingerprints are transformed into feature vectors using standard scaling/translation methods and the Fast Fourier Transform (FFT). The number of features per fingerprint are reduced by banding neighboring features and Principal Component Analysis (PCA). The reduced feature vectors are used with the Expectation Maximization (EM) algorithm to learn parameters for a Gaussian Mixture Model (GMM) to represent normal operation. One-class classification of normal fingerprints is achieved by thresholding the likelihood of a fingerprint feature vectors. Fingerprints were collected from normal operational conditions and seeded non-normal conditions. Preprocessing methods and algorithmic parameters have been selected using an iterative grid search. Average robust true positive rate achieved was 94.76% and best specificity reported is 86.56%.","Title: Hog Feature Human Detection System\nYear: 2016\n\nAbstract: Human detection systems are becoming more important as more automatic and robotic systems are being used in the world. RGB, depth, and thermal images can be used together to produce a better detection system that works in situations where one of the sensors might not produce valuable data. HOG features can provide valuable information for detecting humans in an image and that data can be used to train individual classifiers to detect humans in a scene. The combination of sensor modalities in conjunction with individual classifiers can create a human detection system that can detect partially obscured humans. The multi-layer classifier that was created provided a high level of accuracy when tested against untrained data. The multi-layer classifier performed better than eleven of the twelve individual classifiers, but did not overcome the SVM thermal HOG classifier. The multi-layer classifier had a much tighter standard deviation and fell within the band of the SVM thermal classifier.","Title: American Sign Language Recognition System By Using Surface Emg Signal\nYear: 2016\n\nAbstract: Sign Language Recognition (SLR) system is a novel method that allows hard of hearing people to communicate with society. In this study, an American Sign Language (ASL) recognition system was proposed by using the surface Electromyography (sEMG). The objective of this study is to recognize the American Sign Language alphabet letters and allow users to spell words and sentences. For this purpose, sEMG signals are acquired from subject's right forearm for 27 American Sign Language gestures, 26 English alphabet letters, and one for home position. Time domain, frequency domain (band power), power spectral density (band power), and average power features were used as the feature extraction methods. After feature extraction, Principal Component Analysis (PCA) was applied to obtain uncorrelated features. As a classification method, Support Vector Machine and Ensemble Learning algorithm were used and their performances were compared with tabulated results. In conclusion, the results of this study show that sEMG signal can be used for SLR systems.","Title: Collaborative Robot Learning from Demonstrations using Hidden Markov Model State Distribution.\nYear: 2018\n\nAbstract: In robotics, there is need of an interactive and expedite learning method as experience is expensive. Robot Learning from Demonstration (RLfD) enables a robot to learn a policy from demonstrations performed by teacher. RLfD enables a human user to add new capabilities to a robot in an intuitive manner, without explicitly reprogramming it. In this work, we present a novel interactive framework, where a collaborative robot learns skills for trajectory based tasks from demonstrations performed by a human teacher. The robot extracts features from each demonstration called as key-points and learns a model of the demonstrated skill using Hidden Markov Model (HMM). Our experimental results show that the learned model can be used to produce a generalized trajectory based skill.","Title: Novelty Detection And Analysis With A Beta-Dvae Network\nYear: 2018\n\nAbstract: In this paper we apply generative modeling to Gaussian Mixture Models (GMM) as a solution to high dimensional novel event detection and analysis on radio frequency (RF) power generators. A family of Denoising and beta-Disentangling Variational Autoencoders (beta-DVAE) is used to encode datasets into lower and more salient dimensions. The reduced feature sets are modeled using GMMs where model parameters are learned using the Expectation Maximization (EM) algorithm. The data is obtained from two different generator models operating under normal as well as known not-normal conditions. This approach is also tested on standard classification sets. Robust testing is reported to achieve a target class accuracy of 98.16% for the target RF generator. Additionally, the GMM parameters are decoded by the generative model to the original data space for calculating per-variable fitness in order to provide an initial novel event analysis for engineers and technicians. This per-variable fitness is very critical for determining each variable's contribution to a novelty so that engineers can perform informed trouble shooting and maintenance of the RF generators.","Title: Dynamic Awareness Of An Industrial Robotic Arm Using Time-Of-Flight Laser-Ranging Sensors\nYear: 2018\n\nAbstract: In this paper, a range sensing setup for performing detection and monitoring in an industrial robot workspace is presented. The setup uses a ring of Time-of-Flight laser range sensors mounted on a robot A 3D simulation setup with the properties of the sensor mounted on a UR10 robot and a simple pick and place task with a human avatar is used to analyze its behavior and viability with industrial arm robots. Collision detection strategies based on human-robot separation distance and relative speeds are also implemented. These strategies are evaluated based on the human safety, robot performance and productivity of the task. The parameters and results of the experiments are tabulated. The results show the benefits of achieving dynamic awareness of the robot in comparison with the conventional methods used in industry. The development of the prototype sensor ring is also shown and the future work discussed.","Title: Real-Time Rotation Invariant Action Recognition Using Microsoft Kinect\nYear: 2016\n\nAbstract: A Human Action recognition system is proposed using the Skeletal Tracking from Kinect. The angular information of the joints helps in handling scaling errors. Vectors are generated using the joint coordinates and the angles of each joint are used as features for key pose recognition. A rotational compensation is included in the feature to handle rotational errors. The key poses are recognized using Similarity Matching Technique, neural network and decision tree algorithms. The recognized key postures are fed into a decision forest to pick the action based on the trained sequence of key poses.","Title: Cyber-Physical Testbed for Human-Robot Collaborative Task Planning and Execution\nYear: 2019\n\nAbstract: In this paper, we present a cyber-physical testbed created to enable a human-robot team to preform a shared task in a shared workspace. The testbed is suitable for the implementation of a tabletop manipulation task, a common human-robot collaboration scenario. The testbed integrates elements that exists in the physical and virtual world. In this work, we report the insights we gathered through out our exploration in understanding and implementing task planning and execution for human-robot team.","Title: HRC-SoS: Human Robot Collaboration Experimentation Platform as System of Systems\nYear: 2019\n\nAbstract: This paper presents an experimentation platform for human robot collaboration as a system of systems as well as proposes a conceptual framework describing the aspects of Human Robot Collaboration. These aspects are Awareness, Intelligence and Compliance of the system. Based on this framework case studies describing experiment setups performed using this platform are discussed. Each experiment highlights the use of the subsystems such as the digital twin, motion capture system, human-physiological monitoring system, data collection system and robot control and interface systems. A highlight of this paper showcases a subsystem with the ability to monitor human physiological feedback during a human robot collaboration task.","Title: ORBDeepOdometry - A Feature-Based Deep Learning Approach to Monocular Visual Odometry\nYear: 2019\n\nAbstract: Visual Odometry (VO) is an application of computer vision which helps in autonomous navigation of Self-Driving vehicles, Robots etc. The odometry pose of the vehicle can be estimated using the consecutive frames based on monocular or stereo camera setup mounted on the vehicle. The Simultaneous Localization and Mapping (SLAM) based approaches have shown phenomenal results in predicting the vehicle odometry. Deep Learning based approaches are emerging in the field of computer vision and are outperforming other classic algorithms. But, visual odometry is one of the field where deep learning approaches have not yet been exploited largely. This paper proposes the use of Deep Learning based pipeline approach to solve the problem of visual odometry. The paper boosts the performance of deep learning approach by extracting quite more features before training the network. This paper proposes the use of ORB based feature extractor along with Convolutional Neural Network based dimensionality reduction and stacking multiple deep LSTM's for modelling the sequential data. In this case, the KITTI vision Benchmark dataset is used to model the network. The accuracy of the network is examined by calculating the error between the predicted odometry output and the ground truth odometry output. The results are compared with different Convolutional Neural Network (CNN) architectures proposed for the same task. The average translation error from the proposed system is 11.99% and the average rotational error from the proposed system is 0.0462 degrees per meter.","Title: A Low-Cost Search-and-Rescue Drone for Near Real-Time Detection of Missing Persons\nYear: 2019\n\nAbstract: In this work, an unmanned aerial system is implemented to search an outdoor area for an injured or missing person (subject) without requiring a connection to a ground operator or control station. The system detects subjects using exclusively on-board hardware as it traverses a predefined search path, with each implementation envisioned as a single element of a larger swarm of identical search drones. Imagery is streamed from a camera to an Odroid single-board computer, which prepares the data for inference by a Neural Compute Stick vision accelerator. A single-class TinyYolo network, trained on the Okutama-Action dataset and an original Albatross dataset, is utilized to detect subjects in the prepared frames. The detection apparatus is mounted on a drone and field tests validate the system feasibility and efficacy.","Title: Smart Walker V: Implementation of RTAB-Map Algorithm\nYear: 2019\n\nAbstract: Autonomous Navigation has been a field of major attraction to a large number of robotics enthusiasts all around the globe. Smart walker, a robot designed for assisting patients under intensive care, requires this exceptional add-on in order to have a better sense of the surrounding, captured through the RGB and depth sensor available on board. This paper addresses the navigation and mapping problem through a graph-based SLAM technique knows as Real-Time Appearance-based Mapping (RTAB-Map), which uses an interesting approach to map an area with the help of loop closures, and provides a number of visual feature tracking methods that can be used to detect the loop closures. The software stack on the Smart Walker has been built around ROS (Robot Operating System), and the necessary sensor, odometry and transformation messages have been configured accordingly, based on the onboard sensors and actuators attached to the Smart Walker. This paper discusses the implementation of RTAB-Map algorithm on the Smart Walker and steps involved in collecting a custom dataset. The approach also involves comparing the performance of visual feature tracking methods available in RTAB-Map algorithm on a standard dataset and on the custom dataset, based on non-statistical aspects in order to implement the right set of features for indoor use of the Smart Walker.","Title: Low Computational Complexity Classifier Based On The Maximum Relative Global Peak For The Classification Of Eog Signals\nYear: 2017\n\nAbstract: In this paper, a new low computational complexity machine learning classifier is developed to detect eye movements from an Electrooculography (EOG) signal. The proposed classier is based on finding the maximum relative global peak of a set of signals that are decomposed from the original EOG signals. Unlike many other classifiers, the proposed classifier does not depend on threshold signal levels or spectrum analysis of the EOG signals which require nonlinear and complex operations. The proposed classifier uses four predefined functions which are divided into two groups to distinguish between the horizontal and vertical eye movements. The new proposed classifier can be used for on low powerful boards because it does not require high speed processors where it needs to calculate only one optimum parameter that maximizes the global accuracy. The performance of the proposed classifier is better and faster by 40% than the SVM classifier. In addition, there is a misclassification between two classes only rather than three classes.","Title: Learning Robotic Manipulation Tasks via Task Progress Based Gaussian Reward and Loss Adjusted Exploration\nYear: 2022\n\nAbstract: Multi-step manipulation tasks in unstructured environments are extremely challenging for a robot to learn. Such tasks interlace high-level reasoning that consists of the expected states that can be attained to achieve an overall task and low-level reasoning that decides what actions will yield these states. We propose a model-free deep reinforcement learning method to learn multi-step manipulation tasks. We introduce a Robotic Manipulation Network (RoManNet)\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sup>\n, which is a vision-based model architecture, to learn the action-value functions and predict manipulation action candidates. We define a Task Progress based Gaussian (TPG) reward function that computes the reward based on actions that lead to successful motion primitives and progress towards the overall task goal. To balance the ratio of exploration/exploitation, we introduce a Loss Adjusted Exploration (LAE) policy that determines actions from the action candidates according to the Boltzmann distribution of loss estimates. We demonstrate the effectiveness of our approach by training RoManNet to learn several challenging multi-step robotic manipulation tasks in both simulation and real-world. Experimental results show that our method outperforms the existing methods and achieves state-of-the-art performance in terms of success rate and action efficiency. The ablation studies show that TPG and LAE are especially beneficial for tasks like multiple block stacking.","Title: Learning Multi-step Robotic Manipulation Policies from Visual Observation of Scene and Q-value Predictions of Previous Action\nYear: 2022\n\nAbstract: In this work, we focus on multi-step manipulation tasks that involve long-horizon planning and considers progress reversal. Such tasks interlace high-level reasoning that consists of the expected states that can be attained to achieve an overall task and low-level reasoning that decides what actions will yield these states. We propose a sample efficient Previous Action Conditioned Robotic Manipulation Network (PAC-RoManNet) to learn the action-value functions and predict manipulation action candidates from visual observation of the scene and action-value predictions of the previous action. We define a Task Progress based Gaussian (TPG) reward function that computes the reward based on actions that lead to successful motion primitives and progress towards the overall task goal. To balance the ratio of exploration/exploitation, we introduce a Loss Adjusted Exploration (LAE) policy that determines actions from the action candidates according to the Boltzmann distribution of loss estimates. We demonstrate the effectiveness of our approach by training PAC-RoManNet to learn several challenging multi-step robotic manipulation tasks in both simulation and real-world. Experimental results show that our method outperforms the existing methods and achieves state-of-the-art performance in terms of success rate and action efficiency. The ablation studies show that TPG and LAE are especially beneficial for tasks like multiple block stacking. Additional experiments on Ravens-10 benchmark tasks suggest good generalizability of the proposed PAC-RoManNet.","Title: System Integration of a Tour Guide Robot\nYear: 2022\n\nAbstract: In today’s world, people visit many attractive places. On such an occasion, It is of utmost importance to be accompanied by a tour guide, who is known to explain about the cultural and historical importance of places. Therefore, a human guide is necessary to provide tours for a group of visitors. However, Human tour guides might face tiredness, distraction, and the effects of repetitive tasks while providing tour service to visitors. Robots eliminate these problems and can provide tour consistently until it drains its battery. This experiment introduces a tour-guide robot that can navigate autonomously in a known map of a given place and at the same time interact with people. The environment is equipped with artificial landmarks. Each landmark provides information about that specific region. An Animated avatar is simulated on the screen. IBM Watson provides voice recognition and text-to-speech services for human-robot interaction. The experimental results show that the robot takes average time of 10000 seconds to provide a tour. TEB and DWA local planner are compared by allowing the robot to autonomously maneuver the environment for 9 trials which is tabulated in section V.","Title: iOS Based Pose Estimation and Gesture Recognition for Robot Manipulation\nYear: 2022\n\nAbstract: Interfacing between robots and humans has come a long way in the past few years, and new methods for smart, robust interaction are needed. Typically, a technician has to program a routine for a robot in order for the robot to be useful. This puts up a significant barrier to entry into the field of automating tasks using robots—not only is a technician and a computer required, but the robot is not adaptive to the immediate needs of the user. The robot is only capable of executing a pre-determined task and for any change to be made the entire system needs to be paused. This project seeks to bridge the gap between user and robot interface, creating an easy-to-use system that allows for adaptive robot control. Using a combination of computer vision and a monocular camera system and integrated LiDAR sensor on an iPhone, gesture recognition and pose estimation was conducted within an independent system to control the Baxter humanoid robot. The gathered data was sent wirelessly to the robot to be interpreted and then replay actions performed by the user.","Title: Low Cost Real Time Location Tracking with Ultra-Wideband\nYear: 2022\n\nAbstract: An emerging technology for indoor localization is ultra wide-band, also known as UWB. UWB has been making waves as a system that can be both secure and function as an “indoor GPS The proliferation of UWB is underway and soon it will be as ubiquitous as Bluetooth or Wi-Fi. With this in mind, the benchmarking of the DWM3000EVB module in an Ultra Wideband Real Time Locating System is the goal of this research. The UWB RTLS created is a three anchor - one tag system that can calculate position just under 100 Hz and has an average accuracy of 5 centimeters."],"string":"[\n \"Title: An artificial immune system approach to mobile sensor networks and mine detection\\nYear: 2004\\n\\nAbstract: Abstract - The human immune system and ifs ability to continually develop and learn has been studiedfor many years. Its capacity to recognize its owas those thatpose a threat to the body’s homeostasis (non-se@ has lead to the creation of many algorithms that try to mimic this behavior. One of these algorithms is the Artificial Immune System (AIS). The foundation of AIS depends on the existence of both sensor and communication ranges (assumed circles) with which a single agent can collect and convey information to other agents within the range. It is the purpose of this paper to present a solution to the mine detection problem using cooperative mobile robots equipped with sensory and communication capabilities which allow the AIS approach to be utilized. Keywords: Artificial Immune System, Cooperative\",\n \"Title: Pattern recognition with surface EMG signal based wavelet transformation.\\nYear: 2012\\n\\nAbstract: EMG based input device is a natural means of human computer interface (HCI) because the electrical activity induced by the human's arm muscle movements can be interpreted and transformed into computer's control commands. In this paper, we describe an approach for classifying electromyography (EMG) signals using a multilayer perceptron neural network (MLP) and Bayesian classifier (BC) with the wavelet transformation technique for feature selection to discriminate 6 classes of motions to control a mouse. Wavelet Transformation (WT) was applied to raw EMG data and in order to decrease the dimension of the feature sets, principle component analysis (PCA) and sequential forward selection (SFS) were utilized.\",\n \"Title: Darwinian Particle Swarm Optimization\\nYear: 2005\\n\\nAbstract: Particle Swarm Optimization (PSO), an evolutionary algorithm for optimization is extended to determine if natural selection, or survival-of-the- fittest, can enhance the ability of the PSO algorithm to escape from local op- tima. To simulate selection, many simultaneous, parallel PSO algorithms, each one a swarm, operate on a test problem. Simple rules are developed to imple- ment selection. The ability of this so-called Darwinian PSO to escape local op- tima is evaluated by comparing a single swarm and a similar set of swarms, dif- fering primarily in the absence of the selection mechanism, operating on the same test problem. The selection process is shown to be capable of evolving the best type of particle velocity control, which is a problem specific design choice of the PSO algorithm.\",\n \"Title: An application of human robot interaction: development of a ping-pong playing robotic arm.\\nYear: 2005\\n\\nAbstract: This paper describes the design and development of a ping-pong robotic arm as an application of robotic vision. Displaced frame difference (DFD) is utilized to segment the ball motion from background motion. 3-D ball tracking using parametric calibration of single CCD camera is explained. This visual information is temporally updated and further employed to guide a robot arm to hit the ball at a specified location. The results signify the system development based on single camera tracking. System latency is measured as a function of the camera interface, processor architecture, and robot motion. Various hardware and software parameters that influence the real time system performance are also discussed.\",\n \"Title: Structural Learning Of Bayesian Networks From Complete Data Using The Scatter Search Documents\\nYear: 2004\\n\\nAbstract: Bayesian Networks are directed acyclic graphs that model the dependency relationships between variables of interest. These networks are characterized by the structure of the network and the conditional probabilities that specify the dependencies that exist between the variables. In this paper, the Scatter Search optimization algorithm is utilized in learning the structure of the Bayesian network from complete data. This involves a heuristic search for the best network structure that maximizes a scoring function given a database of cases. The scatter search algorithm is implemented on a database of cases sampled from known networks in order to test the accuracy of the structural learning. Empirical results from the implementations are presented in the paper.\",\n \"Title: Block Matching with Particle Swarm Optimization for Motion Estimation\\nYear: 2013\\n\\nAbstract: Block matching algorithms successfully reduce the computational load of the motion estimation. Block based motion estimation algorithms rely on block matching of the macro blocks defined in the search windows. In this paper, particle swarm optimization (PSO) is applied on block-matching problem. Particle swarm optimization is a computationally efficient iterative search algorithm that finds the best matching block between two consecutive frames. Finding the moving block in the image sequence requires a minimization algorithm. Using particle swarm optimization, the computational cost of the block matching is aimed to decrease. Particle swarm optimization is a heuristic algorithm and necessarily dependent on the selections of the parameters assigned. In our case, the particle swarm algorithm is designed to work on a small subset of the population of blocks. The position of a macro block in the estimated image can be revealed by the motion vectors generated by the particle swarm optimized block.\",\n \"Title: Cooperation of decision-theoretic agents in the context of multi-agent systems.\\nYear: 2003\\n\\nAbstract: Multi-agen: based solutions to problems, whether they are software agents or physical robots, are attractive because they are robust and scalable. Fundamental aspects of designing multi-agent systems involve modeling the intelligence of the agents and modeling their interactions. The intelligences of agents modeled here are encoded in Bayesian representa:ions a/ their world. The agents interact only by observing others and moving in such a way so as to probabilistically maximize their intemalizedgoal or utility. Using this multi- agentfiamework, a three agent herding is explored.\",\n \"Title: Groundscouts: Architecture For A Modular Micro Robotic Platform For Swarm Intelligence And Cooperative Robotics\\nYear: 2004\\n\\nAbstract: This paper presents architecture for a modular micro robotic platform for swarm intelligence and cooperative robotics research and applications. In a swarm the value of an individual is negligible since the goal of the swarm is essential. Thus, the agents (robots) need to be small, low cost, and cooperative. GroundScouts are designed based on these conditions. The proposed architecture slices a robot into abstract modules such as locomotion, control, sensors, communication, and actuation. Any mobile robot can be constructed by combining these abstract modules for a specific application. A modular embedded micro-OS with dynamic task uploading and multi-tasking abilities is developed in order to create better interface between robots and the command center and among the robots. The dynamic task uploading allows the robots change their behaviors in runtime. Thus, the robots can work in swarm, master-slave, or hybrid mode and possibly be used in other applications such as mobile sensor networks, remote sensing, and plant monitoring.\",\n \"Title: Cognitive Maps In Swarm Robots For The Mine Detection Application\\nYear: 2003\\n\\nAbstract: Navigation based on cognition is seen in many instances in the animal community. Maps are very useful for navigation in unknown and complex environments. User defined and preinstalled maps can be very useful in navigation in complex environments, while adoptively built maps become very essential in unknown environments. Intelligence is bestowed in the effective utilization of data to produce decisions. In the case of navigation, intelligence is seen when information collected en-route from a source to a destination is used judiciously in reaching the destination. In this paper we deal with the foraging of a piece of terrain as a process of navigation. The application here is mine detection. Mines are placed over afield at unknown locations and swarm intelligence based agents are deployed for demining them. The efficiency of the demining process is measured in terms of the quickness with which they can clear the mines and the assurance that the minefield is clear of all of the mines at the end of the process. Simulation results acknowledging the performance under different working conditions of the swarm robots are presented In an endeavor to substantiate our claims in simulation we decided to build swarm robots performing the task on an artificially developed environment.\",\n \"Title: Fault diagnosis for airplane engines using Bayesian networks and distributed particle swarm optimization\\nYear: 2007\\n\\nAbstract: This paper presents a fault diagnosis system for airplane engines using Bayesian networks (BN) and distributed particle swarm optimization (PSO). The PSO is inherently parallel, works for large domains and does not trap into local maxima. We implemented the algorithm on a computer cluster with 48 processors using message passing interface (MPI) in Linux. Our implementation has the advantages of being general, robust, and scalable. Unlike existing BN-based fault diagnosis methods, neither expert knowledge nor node ordering is necessary prior to the Bayesian Network discovery. The raw datasets obtained from airplane engines during actual flights are preprocessed using equal frequency binning histogram and used to generate Bayesian networks fault diagnosis for the engines. We studied the performance of the distributed PSO algorithm and generated a BN that can detect faults in the test data successfully.\",\n \"Title: New classification techniques for electroencephalogram (EEG) signals and a real-time EEG control of a robot.\\nYear: 2013\\n\\nAbstract: This paper studies the state-of-the-art classification techniques for electroencephalogram (EEG) signals. Fuzzy Functions Support Vector Classifier, Improved Fuzzy Functions Support Vector Classifier and a novel technique that has been designed by utilizing Particle Swarm Optimization and Radial Basis Function Networks (PSO-RBFN) have been studied. The classification performances of the techniques are compared on standard EEG datasets that are publicly available and used by brain–computer interface (BCI) researchers. In addition to the standard EEG datasets, the proposed classifier is also tested on non-EEG datasets for thorough comparison. Within the scope of this study, several data clustering algorithms such as Fuzzy C-means, K-means and PSO clustering algorithms are studied and their clustering performances on the same datasets are compared. The results show that PSO-RBFN might reach the classification performance of state-of-the art classifiers and might be a better alternative technique in the classification of EEG signals for real-time application. This has been demonstrated by implementing the proposed classifier in a real-time BCI application for a mobile robot control.\",\n \"Title: Lossless compression of color palette images with one-dimensional techniques\\nYear: 2006\\n\\nAbstract: Palette images are widely used on the World Wide Web (WWW) and in game-cartridge applications. Many images used on the WWW are stored and transmitted after they are compressed losslessly with the standard graphics interchange format (GIF), or portable network graphics (PNG). Well-known 2-D compression schemes, such as JPEG-LS and JPEG-2000, fail to yield better compression than GIF or PNG due to the fact that the pixel values represent indices that point to color values in a look-up table. To improve the compression performance of JPEG-LS and JPEG-2000 techniques, several researchers have proposed various reindexing algorithms. We investigate various compression techniques for color palette images. We propose a new technique comprised of a traveling salesman problem (TSP)-based reindexing scheme, Burrows-Wheeler transformation, and inversion ranks. We show that the proposed technique yields better compression gain on average than all the other 1-D compressors and the reindexing schemes that utilize JPEG-LS or JPEG-2000. (C) 2006 SPIE and IS&T.\",\n \"Title: Uniform Cellular Automata Linear Rules for Edge Detection\\nYear: 2013\\n\\nAbstract: In this paper we discuss the application of two-dimensional linear cellular automata rules to the problems of edge detection in monochromatic images. We proposed an efficient and simple method of edge detection based on uniform cellular automata transition matrix representation. We investigate of cellular automata linear rules for edge detection by using matrix representation, in some cases they are strong and some other rules are not in fact useful for practical edge detection. All rules give computationally effective result since the computation mechanism consist only matrix multiplication. Finally, we present some results of the proposed linear rules for edge detection and compare with some classical results.\",\n \"Title: An XML based system of systems discrete event simulation communications framework\\nYear: 2009\\n\\nAbstract: Simulations play an important role in complex systems development. In a System of Systems (SoS) consisting of heterogeneous independent systems (as is the case with cooperative robotics, for example), effective communication among the systems is essential. This paper extends the application of Extensible Markup Language (XML) as a method of wrapping data without imposing other restrictions on the systems in an SoS. The effort to model and implement XML communication among members of an SoS is based on Discrete Event Specification (DEVS) and uses DEVSJAVA software as the simulator. An XML based SoS simulation framework is presented by a robust threat detection scenario involving multiple heterogeneous systems working cooperatively to accomplish the goal. This framework will also support agent-in-the-loop simulations using real time DEVS modeling in future work.\",\n \"Title: Autonomous Navigation Based On A Q-Learning Algorithm For A Robot In A Real Environment\\nYear: 2008\\n\\nAbstract: This paper explores autonomous navigation and obstacle avoidance techniques based on Q-learning for a mobile robot in a real environment. The implemented algorithm focuses on simplicity and efficiency. The learning process takes place in both simulation and real world allowing the combination of a longer learning time in the simulator with a more accurate knowledge from the real world. After learning is completed in simulation and in the real world the robot was able to navigate without hitting obstacles and able to generate control law for complex situations such as corners and small objects.\",\n \"Title: Decision Theoretic Agent Design For Personal Rapid Transit Systems\\nYear: 2007\\n\\nAbstract: This paper details a learning decision-theoretic intelligent agent designed to solve the problem of guiding vehicles in the context of Personal Rapid Transit (PRT). The intelligent agents are designed using Bayesian Decision Networks. The agents are designed to utilize the known methods of machine learning with Bayesian Networks (BN): parameter learning and structure learning. In addition, a new method of machine learning with BNs, termed utility learning in this paper, is introduced. BN software for Matlab is used to realize the proposed agent. Additional software is written to simulate the PRT problem using various intelligent agents that utilize one or more learning methods.\",\n \"Title: A Discrete Event Xml Based System Of Systems Hardware-In-The-Loop Simulation For Robust Threat Detection\\nYear: 2009\\n\\nAbstract: In a system of systems (SoS) consisting of heterogeneous independently operable systems, successfully sending, receiving, and understanding data is necessary to achieve interoperation among the systems. Extensible Markup Language (XML) is applied to wrap the data in a way that is commonly understood in the SoS while the asynchronous nature of the interactions among systems is viewed as an event driven system. Discrete event specification (DEVS) formalism is used to describe the models composing the SoS. Simulation provides a means to examine and analyze systems and their interactions as well as how a new system effects the SoS but can hide issues that arise during final implementation. Hardware-in-the-loop (HIL) simulation provides a bridge between simulation and implementation in order to reduce build cost and more readily verify a system's desired performance. A Groundscout robot is used as a real system in the simulation of a robust threat detection scenario.\",\n \"Title: In-Vivo Fault Analysis and Real-Time Fault Prediction for RF Generators Using State-of-the-Art Classifiers\\nYear: 2013\\n\\nAbstract: In this paper we apply various machine learning techniques for fault detection of RF (Radio Frequency) Power Generators. Fast Fourier Transform features are used in our analysis for all experiments. Radial Basis Function Networks (RBF) is used to build a two class classifier to differentiate between normal and one fault condition. We apply three one class classifiers to model the normal operating conditions. The data is obtained from five different generators of the same model type.\",\n \"Title: Robust Recruitment Near The Edge Of Chaos And An Application To Mine Sweeping\\nYear: 2003\\n\\nAbstract: The field of robotics is in rapid development. As robots become cheaper to build, new applications involving many robot systems can be envisioned One reason for using many robots is to achieve robustness. Having many robots, however, does not ensure robustness. A control strategy and robot behaviors must be engineered to incorporate robustness into the system. Swarm intelligence based approaches are popular for developing optimal and robust control strategies for systems of robots. Here we analyze the behavior of a swarm of robots modeled after a swarm of ants, where tasks are spatially distributed in the environment and robots/ants are recruited through short-range recruitment. For ants that move probabilistically in response to the short range signal and who adjust their probabilities such that they are near a phase change boundary, or edge-of-chaos, in the mean field analysis of their motions, we find a significant improvement in the robustness of the system.\",\n \"Title: FPGA implementation of particle swarm optimization for Bayesian network learning\\nYear: 2013\\n\\nAbstract: Using a Bayesian network (BN) learned from data can aid in diagnosing and predicting failures within a system while achieving other capabilities such as the monitoring of a system. However, learning a BN requires computationally intensive processes. This makes BN learning a candidate for acceleration using reconfigurable hardware such as field-programmable gate arrays (FPGAs). We present a FPGA-based implementation of BN learning using particle-swarm optimization (PSO). This design thus occupies the intersection of three areas: reconfigurable computing, BN learning, and PSO. There is significant prior work in each of these three areas. Indeed, there are examples of prior work in each pair among the three. However, the present work is the first to study the combination of all three. As a baseline, we use a prior software implementation of BN learning using PSO. We compare this to our FPGA-based implementation to study trade-offs in terms of performance and cost. Both designs use a master-slave topology and floating-point calculations for the fitness function. The performance of the FPGA-based version is limited not by the fitness function, but rather by the construction of conditional probability tables (CPTs). The CPT construction only requires integer calculations. We exploit this difference by separating these two functions into separate clock domains. The FPGA-based solution achieves about 2.6 times the number of fitness evaluations per second per slave compared to the software implementation.\",\n \"Title: Application Of Soft Computing Techniques To Estimate The Effective Young'S Modulus Of Thin Film Materials\\nYear: 2007\\n\\nAbstract: This research aims at characterizing and predicting the Young's Modulus of thin film materials that are utilized in Microelectromechanical systems (MEMS). Recent studies indicate that the mechanical properties such as Young's Modulus of thin films are significantly different from the bulk values. Due to the lack of proper understanding of the physics in the micro-scale domain the state-of-art estimation techniques are unreliable and often unfit for use for predicating the mechanical behavior of slight modifications of existing designs as well as new designs. This disadvantage limits the MEMS designers to physical prototyping which is cost ineffective and time consuming. As a result there is an immediate need for alternative techniques that can learn the complex relationship between the various parameters and predict the effective Young's Modulus of the thin films materials. The proposed technique attempts to solve this problem using empirical estimation techniques that utilize soft computing techniques for the estimation as well as the prediction of the effective Young's Modulus. As a proof of concept, effective Young's Modulus of Aluminum and TetrathylOrthoSilicate (TEOS) thin films were computed by fabricating and analyzing self-deformed micromachined bilayer cantilevers. In the estimation phase, 2D search and micro Genetic algorithm were studied and in the prediction phase, back propagation based Neural networks and One Dimensional Radial Basis Function Networks (1D-RBFN) were studied. The performance of all combinations of these soft computing techniques is studied. Based on the results, we conclude that performance of the soft computing techniques is superior to the existing methods. In addition, the effective values generated using this methodology is comparable to the values reported in the literature. Given a finite number of data samples, the combination of 1D-RBFN (prediction phase) and GA (estimation phase) presented the best results. Due to these advantages, this methodology is foreseen to be an essential tool for developing accurate models that can estimate the mechanical behavior of thin films.\",\n \"Title: Application of Particle Swarm Optimization for Traveling Salesman Problem to lossless compression of color palette images.\\nYear: 2008\\n\\nAbstract: This paper investigates optimal color indexing for the compression of color palette images. This work enhances the recent traveling salesman problem (TSP) based re-indexing technique with particle swarm optimization (PSO). In this work, color re-indexing is done by solving the problem as a TSP using PSO. The proposed technique, yields better compression gains than the recent work that used a cross entropy (CE) based TSP for re-indexing.\",\n \"Title: A survey on feature selection methods\\nYear: 2014\\n\\nAbstract: Plenty of feature selection methods are available in literature due to the availability of data with hundreds of variables leading to data with very high dimension. Feature selection methods provides us a way of reducing computation time, improving prediction performance, and a better understanding of the data in machine learning or pattern recognition applications. In this paper we provide an overview of some of the methods present in literature. The objective is to provide a generic introduction to variable elimination which can be applied to a wide array of machine learning problems. We focus on Filter, Wrapper and Embedded methods. We also apply some of the feature selection techniques on standard datasets to demonstrate the applicability of feature selection techniques.\",\n \"Title: Design of Intelligent Agents for Personal Rapid Transit\\nYear: 2007\\n\\nAbstract: This paper presents machine learning concepts to successfully implement an intelligent agent solution to the problem of autonomous control of Personal Rapid Transit (PRT) vehicles. The PRTs can operate independently and together as a whole system. Thus, they can be considered as a system of systems. By developing a set of rules for the vehicles to follow, the various parts of a Bayesian Network (BN), its nodes, parameters, structure and utility function are determined. The variables in the network are generated from the sensor data of the PRT vehicles. Using the overall system goals, a utility function can be devised that will select the best action for an agent to take. Simulation results show that this methodology is useful for \\\"rapid prototyping\\\" a decision theoretic agent. The gap between the intelligent agent and rule based agent performance for the collision metrics suggests that more research is needed to develop a systematic method of creating utility functions to meet system goals.\",\n \"Title: Application Of Swarm Intelligence To The Mine Detection Problem\\nYear: 2004\\n\\nAbstract: This paper will highlight the important points of swarm intelligence, more specifically the Ant Algorithm, and illustrate how it can be applied to a real time mine defection problem. The algorithm will be applied using GroundScouts, a modular micro robot that was designed for cooperative robotics applications. An Adaptive Time Division Multiple Access (ATDMA) communication scheme will also be presented that changes the behavior of the network according to the number of robots on the network. This maximizes the efficiency of the communication between the robots. The results will show that the real time implementation of the algorithm is successful.\",\n \"Title: A comparison of chatter attenuation techniques applied to a twin rotor system\\nYear: 2014\\n\\nAbstract: The twin rotor MIMO system (TRMS) is a helicopter-like system that is restricted to two degrees of freedom, pitch and yaw. It is a complicated nonlinear, coupled, MIMO system used for the verification of control methods and observers. This paper compares the ability of three adaptive sliding mode controllers (SMC) to suppress chattering. Once the design is complete the controllers are implemented in simulation and experimentally. The performance of the controllers are compared against a PID controller and other controllers in the literature. The ability of the sliding mode controllers (SMC) to suppress chattering is also be explored.\",\n \"Title: Embedded one-class classification on RF generator using Mixture of Gaussians\\nYear: 2014\\n\\nAbstract: In this paper we apply a specific machine learning technique for classification of normal and not-normal operation of RF (Radio Frequency) power generators. Pre-processing techniques using FFT and bandpower convert time-series system signatures into single feature vectors. These feature vectors are modeled using k-component Mixture of Gaussians (MoG) where components and corresponding parameters are learned using the Expectation Maximization (EM) algorithm. Data is obtained from three different generator models operating under normal and multiple different not-normal conditions. Exploration into algorithmic parameter effects is conducted and empirical evidence used to select sub-optimum parameters. Robust testing is reported to achieve a 3s classification accuracy of 95.91% for the targeted RF generator. Additionally, a custom C++ library is implemented to utilize the learned model for accurate classification of time-series data within an embedded environment such as a RF generator. The embedded implementation is reported to have a small storage footprint, reasonable memory consumption and overall fast execution time.\",\n \"Title: Ant colony optimization based swarms: implementation for the mine detection application\\nYear: 2004\\n\\nAbstract: Mine detection is a sensitive task confronting the battlefield strategists. There is an ever-increasing demand for proper and sophisticated resources for many issues involved in the task. Traditional practices still involve human force directly in executing the tasks in spite of the advances in technology for tools and implements for the operation [GAO, 2001]. The problem includes various facets inherently: two of the prominent issues are location of mines over a minefield and secondly removal of the mines once located [GAO, 2001]. These two issues are not totally independent as technology used for one can directly or indirectly affect the other. Developments in artificial intelligence, natural heuristics, computational optimization and robotics have endowed us with the ability to realize unmanned robots (or robot like vehicles) that work intelligently on a real time basis in attempting at the problem of mine detection. In this paper we focus on the algorithms developed using ant colony optimization based approaches to the mine detection application and its implementation on a real-time basis. We focus on certain optimization techniques that could be used for effective realization of the algorithm. Generic groundscout robots had been already built at the MABL, RIT [Sahin F. et al., 2003]. These robots have been used to demonstrate the implementation\",\n \"Title: Generating and exploiting bayesian networks for fault diagnosis in airplane engines\\nYear: 2006\\n\\nAbstract: Bayesian Networks has been proven to be successful too[ for fault diagnosis. There are a variety of approaches for learning the structure of Bayesian Networks from data. This learning problem has been proven to be NP-hard hence none of the approaches are exact when no prior knowledge about the domain of the variables exists. Our approach is based on searching the best network by using particle swarm optimization (PSO) technique. PSO is inherently parallel, works for large domains and does not trap into local maxima. This paper is an application of this technique to a real world problem; fault diagnosis of an airplane engine for oil related variables. It is implemented by our improved software written in C/C++ by using MPI on Linux. Our implementation has the advantages of being general, robust and scalable. Moreover neither expert knowledge, nor node ordering is necessary prior to the optimization. The datasets are generated by preprocessing oil related sensor readings of airplane engines taken during the approach phase of flights. Using this datasets and our software, we constructed Bayesian Networks of the oil related variables in an airplane engine for diagnostics and predictive purposes.\",\n \"Title: A Discrete Event XML based Simulation Framework for System of Systems Architectures\\nYear: 2007\\n\\nAbstract: System of systems (SoS) concept is essential in solving the issues in complex systems where there are heterogeneous independently operable systems. In order for these independent systems to establish an SoS, they need to understand each other through effective communication. Thus, there is a need for a common language which wraps the data that is sent and received from a system within an SoS. This paper presents the application of extensible markup language (XML) to represent data communicated among systems without underlying differences in hardware software of the individual systems. Moreover, since the operation of each system is asynchronous in nature, the entire SoS can be considered as an event driven system. This paper presents a simulation framework to simulate the structure of the systems in an event driven fashion and wraps the data with a common language. The DEVSJAVA software is used as the discrete event simulator. In addition, XML based encapsulation is created in the DEVSJAVA environment to in the SoS.\",\n \"Title: A discrete event XML based system of systems simulation for robust threat detection and integration\\nYear: 2008\\n\\nAbstract: In a system of systems (SoS) consisting of heterogeneous independently operable systems, effective communication among the systems is essential. These independent systems need to understand each other through effective communication in or order for them to establish a SoS. Thus, there is a need for a common language which wraps the data that is sent and received from a system within a SoS. This paper presents and extends the application of extensible markup language (XML) to represent data communicated among systems without underlying differences in hardware/software of the individual systems. Moreover, since the operation of each system is asynchronous in nature, the entire SoS can be considered as an event driven system. This paper extends an XML based SoS simulation framework to simulate a robust threat detection and integration problem. The DEVSJAVA software is used as the discrete event simulator. Finally, XML based encapsulation is created in the DEVSJAVA environment to create the common language for the heterogeneous systems in a SoS.\",\n \"Title: A study of crossover operators and reference set sizes for scatter search in unconstrained function optimization\\nYear: 2011\\n\\nAbstract: This paper explores different crossover operators and how they affect the Scatter Search (SS) algorithm in unconstrained function optimization. It also explores how the size of the reference set affects convergence and robustness. An introduction to Scatter Search is given along with the typical template. It follows with a thorough explanation of the specific implementation that is used. Two types of tests are designed: (1) what is the best fitness value that it can reach within a maximum number of fitness evaluations and (2) how fast it can converge to goal fitness. These tests are performed using different crossover operators and reference set sizes. Results are also compared apples to apples with a basic implementation of Particle Swarm Optimization (PSO). The results show that although PSO is quicker at converging, SS shows more robustness with higher overall success rates.\",\n \"Title: Computing optimal snowplow route plans using Genetic Algorithms\\nYear: 2011\\n\\nAbstract: The road network of a small town is represented by a directed graph. Road junctions are the vertices of this graph and each road segment (which has a length and a priority value) is represented by a directed edge. Priority values are numbers 1, 2, etc. with the assumption that 1 is the highest priority. We seek to compute an optimal route map that begins at a particular vertex (the depot) and covers all the edges at least once and returns to the start vertex. The parameters that we wish to minimize are: the total distance covered (thereby minimizing the deadhead miles), the number of u-turns and priority misplacements. In this paper, we propose a Genetic Algorithms-based solution to compute near-optimal route maps in such a graph. Specifically, we have developed a Java software application that generates route maps that minimize a linear combination of the three parameters. We have experimented with reasonably large graphs and obtained good solutions. These solutions are especially useful in snowplow routing for small towns, as plowing costs consume significant portions of the total municipal budgets of these communities. Most of the route planning is currently done manually and routes have evolved over time by experience. In these times of severe budget stress, route planning using our approach can help in performing this essential service in an efficient manner.\",\n \"Title: Extraction of memory colors using Bayesian Networks\\nYear: 2009\\n\\nAbstract: In this work, a region classification algorithm based on low-level features and probabilistic framework is proposed where skin, sky, and vegetation memory color classes are detected in digital images. A region's low-level features are extracted using a segmentation map of input image. Bayesian network (BN) is used to classify memory color regions for smart rendering in printing applications. Other applications of the proposed technique include image annotation, indexing, and content retrieval. The algorithm was tested on a large database of color images with 85% classification accuracy.\",\n \"Title: A System of Systems approach to model an Artificial Immune System using Discrete Event Specification\\nYear: 2009\\n\\nAbstract: An artificial immune system (AIS) is a biological inspiration of the human immune system and continues to emerge as a technique for a wide area of applications. This paper presents a model of AIS as it applies to a multi-agent formation problem, similar to predator and prey scenario. Successful multi-agent formations are discovered in conjunction with the artificial immune system's agents and their behaviors. The hierarchy of agents within the artificial immune system support; a system of systems (SoS) based development strategy. The AIS SoS model is implemented based on discrete event specification (DEVS) and simulated using the DEVSJAVA software framework. The resulting model and simulation demonstrates successfully created multi-agent formations of predator around a single prey.\",\n \"Title: An XML based system of systems agent-in-the-loop simulation framework using discrete event simulation\\nYear: 2009\\n\\nAbstract: This paper extends an XML based system of systems simulation framework using DEVS to support hardware-in-the-loop simulations for SoS. A system of systems approach enables the simulation and analysis of multiple complex, independent, and cooperative systems by concentrating on the data transferred among systems. This paper wraps information exchanged among heterogeneous systems in XML to enable receiving systems to correctly parse and interpret the information. A Groundscout robot is deployed as a real agent working cooperatively with virtual agents in a robotic swarm. The DEVS activity concept facilitates communication between the real system and virtual systems in the SoS. A robust threat detection example is provided. Initial performance metrics of the SoS are briefly discussed.\",\n \"Title: A net-centric XML based system of systems architecture for human tracking\\nYear: 2010\\n\\nAbstract: Human detection and tracking is a primary focus for visual surveillance systems. However, current systems for human tracking are often complex and require vast amounts of computing resources. A reduction in complexity of the overall tracking system can be achieved by using a System of Systems (SoS) architecture. Once formed, a SoS architecture must achieve desirable levels of interoperability and integration. Proposed in this paper is a human tracking system that uses a net-centric SoS architecture capable of detecting a human via video surveillance and subsequently providing coordinates for mobile robot tracking. This SoS architecture establishes integration and conceptual interoperability through the standardization of communication and data representation. Within the SoS, communication is accomplished using a client-server architecture while data is structured according to a custom XML framework. The resulting SoS is composed of decentralized independent systems inter-operating on heterogeneous platforms to achieve the ultimate goal of human tracking.\",\n \"Title: Agent-in-the-loop simulation for testing swarm robots using an XML-based system of system framework in discrete-event simulation specification\\nYear: 2011\\n\\nAbstract: This work builds upon our previous work, where a swarm robot called a Groundscout was tested for its emergent behavior(s) using a system of systems framework based on discrete-event simulation and XML-based hardware in the loop simulation (HIL). This paper presents performance optimizations, bug-fixes, and implementations of new features to further examine the benefits of using HIL simulations to develop and test swarm robots. In this work, the Groundscout's communications protocols were improved, a new obstacle-avoidance algorithm was added, and the environment and simulation engines have been either re-implemented or optimized for performance. Specifically for the obstacle-avoidance algorithm, the benefits of using HIL simulations, together with the principle of model continuity, are clearly demonstrated with testing experiments. Towards the eventual goal of creating simulations for testing emergent behaviors of much larger robot swarms, considerations that were learned are presented.\",\n \"Title: In-vivo fault prediction for RF generators using variable elimination and state-of-the-art classifiers\\nYear: 2012\\n\\nAbstract: In this paper we apply two variable elimination algorithms to data obtained from an RF (Radio Frequency) Power Generator Fault Mode for analysis. We use a two wrapper approach using Support Vector Machines (SVM) and Radial Basis Function Networks (RBF) to build an efficient classifier with variable elimination. Comparisons are made for both continuous and discrete datasets.\",\n \"Title: Net-centric System of Systems framework for human detection\\nYear: 2013\\n\\nAbstract: System of Systems (SoS) architectures have been used to conceptually define complex systems. However, very few SoS architectures have been physically realized to solve real-world problems. Proposed in this work is the full realization of a net-centric SoS architecture used to implement and integrate a complex system used to automate human detection from an image source. A SoS architecture was selected to implement the human detection system due to a SoS's ability to achieve high levels of interoperability. This high level of interoperability is feasible via standardization of communication and by structuring information to conform to a proposed XML framework. Additionally, each individual system within the SoS hierarchy is functionally decomposed based on sets defined services that each system requires and provides. Moreover, a new concept of a commonly implemented directory service is used to initialize system communication and automate SoS architecture discovery.\",\n \"Title: Simultaneous localization and mapping using a micro-particle swarm optimization\\nYear: 2015\\n\\nAbstract: Scan matching is a popular way of calculating a robot's position given range data corresponding to objects in the environment. This paper proposes a simultaneous localization and mapping algorithm that uses micro-particle swarm optimization as an alternative method to the traditional scan matching algorithms. The effectiveness of this algorithm is tested and compared to other popular simultaneous and localization algorithms.\",\n \"Title: A framework for a real time intelligent and interactive Brain Computer Interface.\\nYear: 2015\\n\\nAbstract: •A framework for a real time implementation of a Brain Computer Interface.•Implementation & comparison of different feature extraction methods and classifiers.•Accuracy & processing time comparison for detection of event related potentials-ERP.•An implementation of a prototype system using the proposed BCI framework.•Real time EEG data collection and classification of ERPs using Hex-O-Speller.\",\n \"Title: Edge detection with fuzzy cellular automata transition function optimized by PSO\\nYear: 2015\\n\\nAbstract: Fig. 2. Proposed method result of different rules for Im 1 ( Δ = 110 , ¿ = 0.62 ), (a) Original Image, (b) Ground Truth, (c) Rule 47, (d) Rule 170, (e) Rule 367, (f) Rule 510.Display Omitted This study is the application of 2D linear cellular automata (CA) rules with the help of fuzzy membership function to the problems of edge detection.An efficient and simple thresholding technique of edge detection based on CA transition rules optimized by Particle Swarm Optimization method (PSO) is proposed.Results of the proposed to the selected 22 images from the Berkeley Segmentation Dataset (BSDS) are presented.Comparison with some classical Sobel and Canny results is included.Baddeley Delta Metric (BDM) is used for the performance index to compare the results. In this paper we discuss the application of two-dimensional linear cellular automata (CA) rules with the help of fuzzy heuristic membership function to the problems of edge detection in image processing applications. We proposed an efficient and simple thresholding technique of edge detection based on fuzzy cellular automata transition rules optimized by Particle Swarm Optimization method (PSO). Finally, we present some results of the proposed linear rules for edge detection to the selected 22 images from the Berkeley Segmentation Dataset (BSDS) and compare with some classical Sobel and Canny results. Also, Baddeley Delta Metric (BDM) is used for the performance index to compare the results.\",\n \"Title: Modeling and dynamic control for a hexapod robot\\nYear: 2015\\n\\nAbstract: In the every expanding field of robotics, mobile robots come in a two primary variations: wheeled and legged. This paper will focus on the latter, specifically a hexapod with a circular body that has its six legs distributed axisymmetrically around the body. The core goal of the project discussed here is to allow the robot to dynamically change foot placement based on an input vector in addition to controlling the position and orientation of the body. Specific attention is also given to a simulation model that can mimic this control of the robot in a virtual environment. Having a high level of control enhances the robot's ability to move in a very smooth and purposeful manner.\",\n \"Title: A system of systems analysis of a multi-probe SPM system\\nYear: 2015\\n\\nAbstract: In this paper, we introduce a multi-probe Scanning Probe Microscopy (SPM) tool in the context of system of systems (SoS) concepts. The tool exhibits strong characteristics of SoS such as interoperability, integration and independency of each individual system. Each probe terminal constitutes an independent scanning system that can operate individually. The interoperability of the systems through signal exchange bring strong advantages and help users in order to design innovative applications that would not be easily achievable when a single system is used. As an independent system, each probe terminal includes its own controller and feedback mechanism for precise operation which is controlled by individual software running on control PCs. After introducing the overall system, we briefly mention one of the innovative real-world applications that we have been currently working on in an effort to show the strength of SoS engineering and filling the gap between theory and practice.\",\n \"Title: Omnidirectional rule-based free gait utilizing restrictedness\\nYear: 2015\\n\\nAbstract: Adaptable gaits are pivotal for allowing legged robots to navigate difficult terrain. One of the best gait styles to accomplish this goal is the rule-based free gait. First the forward and inverse kinematic solutions are solved for TigerBug, a circular hexapod. Then a rule based free gait is implemented on the circular hexapod in order to provide a platform for future rough terrain navigation.\",\n \"Title: Dual flexible 7 DoF arm robot learns like a child to dance using Q-learning\\nYear: 2015\\n\\nAbstract: Many attempts have been made by researchers and scholars to make people feel more conversant to robots. One such example is the dance performance of an Entertainment Robot. In most cases, the challenge to program dance motions for a robot and synchronize them has been too heavy. In addition, pre-programmed dance moves and synchronization information are useful only for a specific music track and are useless for any other. To solve these problems, we developed a new system that can make a robot learn dance moves according to the input music track. The system comprises of two main parts: the first is a beat extraction system for music track; and the second one is a system that learns dance motion for Baxter. In the first part, music track is analyzed using STFT and peak-to-peak time duration is computed. This gives the beats per minute (BPM) of the given music track. The second part takes the BPM and duration of track and feeds it to the developed Q-learning algorithm to make Baxter learn dance moves and synchronize dance motion to beat rate.\",\n \"Title: A Framework For Intelligent Creation Of Edge Detection Filters\\nYear: 2015\\n\\nAbstract: In this paper, we introduce a framework for a system which intelligently assigns an edge detection filter to an image based only on features taken from the image. The system has four parts, the training set which consists of an image and its edge image ground truth, feature extraction, training filter creation, and system training. A prototype system of this framework is given. In the system feature extraction is performed using a GIST methodology which extracts color, intensity, and orientation information as features. The set of image features are used as the input to a single hidden layer feed forward neural network trained using back propagation. The system trains against a set of linear Cellular Automata filters which are determined to best solve the edge image according to the Baddelay Delta Metric. This metric takes into account false positives and false negative error by scaling the errors relative to the perpendicular distance that they are off from the ground truth. The system was trained and tested against the images from the Berkeley Segmentation Database. The results from the testing indicate that the system performs better than standard methods in many cases but on the whole is only on par across a wide range of images.\",\n \"Title: Real-Time American Sign Language Recognition System Using Surface EMG Signal\\nYear: 2015\\n\\nAbstract: Sign Language Recognition (SLR) system is a method which allow deaf people to communicate with society. In this study, Real-Time Sign Language recognition system was proposed by using the surface Electromyography (sEMG). To this purpose, sEMG data acquired from subject right forearm for all twenty six American Sign Language gestures. Raw sEMG data was filtered, feature extracted and fed into classification. Support Vector Machine (SVM) with one vs. all approach was used for multi class classification. The experiment result of offline system is reaching a recognition rate of 91.% accuracy and real-time system has a recognition rate of 82.3% accuracy. The results of the proposed system shows that sEMG signal can be used for Real-Time SLR systems.\",\n \"Title: Systemic health evaluation of RF generators using Gaussian mixture models.\\nYear: 2016\\n\\nAbstract: We propose an application of specific machine learning techniques capable of evaluating systemic health of a Radio Frequency (RF) power generator. System signatures or fingerprints are collected from multivariate time-series data samples of sensor values under typical operational loads. These fingerprints are transformed into feature vectors using standard scaling/translation methods and the Fast Fourier Transform (FFT). The number of features per fingerprint are reduced by banding neighboring features and Principal Component Analysis (PCA). The reduced feature vectors are used with the Expectation Maximization (EM) algorithm to learn parameters for a Gaussian Mixture Model (GMM) to represent normal operation. One-class classification of normal fingerprints is achieved by thresholding the likelihood of a fingerprint feature vectors. Fingerprints were collected from normal operational conditions and seeded non-normal conditions. Preprocessing methods and algorithmic parameters have been selected using an iterative grid search. Average robust true positive rate achieved was 94.76% and best specificity reported is 86.56%.\",\n \"Title: Hog Feature Human Detection System\\nYear: 2016\\n\\nAbstract: Human detection systems are becoming more important as more automatic and robotic systems are being used in the world. RGB, depth, and thermal images can be used together to produce a better detection system that works in situations where one of the sensors might not produce valuable data. HOG features can provide valuable information for detecting humans in an image and that data can be used to train individual classifiers to detect humans in a scene. The combination of sensor modalities in conjunction with individual classifiers can create a human detection system that can detect partially obscured humans. The multi-layer classifier that was created provided a high level of accuracy when tested against untrained data. The multi-layer classifier performed better than eleven of the twelve individual classifiers, but did not overcome the SVM thermal HOG classifier. The multi-layer classifier had a much tighter standard deviation and fell within the band of the SVM thermal classifier.\",\n \"Title: American Sign Language Recognition System By Using Surface Emg Signal\\nYear: 2016\\n\\nAbstract: Sign Language Recognition (SLR) system is a novel method that allows hard of hearing people to communicate with society. In this study, an American Sign Language (ASL) recognition system was proposed by using the surface Electromyography (sEMG). The objective of this study is to recognize the American Sign Language alphabet letters and allow users to spell words and sentences. For this purpose, sEMG signals are acquired from subject's right forearm for 27 American Sign Language gestures, 26 English alphabet letters, and one for home position. Time domain, frequency domain (band power), power spectral density (band power), and average power features were used as the feature extraction methods. After feature extraction, Principal Component Analysis (PCA) was applied to obtain uncorrelated features. As a classification method, Support Vector Machine and Ensemble Learning algorithm were used and their performances were compared with tabulated results. In conclusion, the results of this study show that sEMG signal can be used for SLR systems.\",\n \"Title: Collaborative Robot Learning from Demonstrations using Hidden Markov Model State Distribution.\\nYear: 2018\\n\\nAbstract: In robotics, there is need of an interactive and expedite learning method as experience is expensive. Robot Learning from Demonstration (RLfD) enables a robot to learn a policy from demonstrations performed by teacher. RLfD enables a human user to add new capabilities to a robot in an intuitive manner, without explicitly reprogramming it. In this work, we present a novel interactive framework, where a collaborative robot learns skills for trajectory based tasks from demonstrations performed by a human teacher. The robot extracts features from each demonstration called as key-points and learns a model of the demonstrated skill using Hidden Markov Model (HMM). Our experimental results show that the learned model can be used to produce a generalized trajectory based skill.\",\n \"Title: Novelty Detection And Analysis With A Beta-Dvae Network\\nYear: 2018\\n\\nAbstract: In this paper we apply generative modeling to Gaussian Mixture Models (GMM) as a solution to high dimensional novel event detection and analysis on radio frequency (RF) power generators. A family of Denoising and beta-Disentangling Variational Autoencoders (beta-DVAE) is used to encode datasets into lower and more salient dimensions. The reduced feature sets are modeled using GMMs where model parameters are learned using the Expectation Maximization (EM) algorithm. The data is obtained from two different generator models operating under normal as well as known not-normal conditions. This approach is also tested on standard classification sets. Robust testing is reported to achieve a target class accuracy of 98.16% for the target RF generator. Additionally, the GMM parameters are decoded by the generative model to the original data space for calculating per-variable fitness in order to provide an initial novel event analysis for engineers and technicians. This per-variable fitness is very critical for determining each variable's contribution to a novelty so that engineers can perform informed trouble shooting and maintenance of the RF generators.\",\n \"Title: Dynamic Awareness Of An Industrial Robotic Arm Using Time-Of-Flight Laser-Ranging Sensors\\nYear: 2018\\n\\nAbstract: In this paper, a range sensing setup for performing detection and monitoring in an industrial robot workspace is presented. The setup uses a ring of Time-of-Flight laser range sensors mounted on a robot A 3D simulation setup with the properties of the sensor mounted on a UR10 robot and a simple pick and place task with a human avatar is used to analyze its behavior and viability with industrial arm robots. Collision detection strategies based on human-robot separation distance and relative speeds are also implemented. These strategies are evaluated based on the human safety, robot performance and productivity of the task. The parameters and results of the experiments are tabulated. The results show the benefits of achieving dynamic awareness of the robot in comparison with the conventional methods used in industry. The development of the prototype sensor ring is also shown and the future work discussed.\",\n \"Title: Real-Time Rotation Invariant Action Recognition Using Microsoft Kinect\\nYear: 2016\\n\\nAbstract: A Human Action recognition system is proposed using the Skeletal Tracking from Kinect. The angular information of the joints helps in handling scaling errors. Vectors are generated using the joint coordinates and the angles of each joint are used as features for key pose recognition. A rotational compensation is included in the feature to handle rotational errors. The key poses are recognized using Similarity Matching Technique, neural network and decision tree algorithms. The recognized key postures are fed into a decision forest to pick the action based on the trained sequence of key poses.\",\n \"Title: Cyber-Physical Testbed for Human-Robot Collaborative Task Planning and Execution\\nYear: 2019\\n\\nAbstract: In this paper, we present a cyber-physical testbed created to enable a human-robot team to preform a shared task in a shared workspace. The testbed is suitable for the implementation of a tabletop manipulation task, a common human-robot collaboration scenario. The testbed integrates elements that exists in the physical and virtual world. In this work, we report the insights we gathered through out our exploration in understanding and implementing task planning and execution for human-robot team.\",\n \"Title: HRC-SoS: Human Robot Collaboration Experimentation Platform as System of Systems\\nYear: 2019\\n\\nAbstract: This paper presents an experimentation platform for human robot collaboration as a system of systems as well as proposes a conceptual framework describing the aspects of Human Robot Collaboration. These aspects are Awareness, Intelligence and Compliance of the system. Based on this framework case studies describing experiment setups performed using this platform are discussed. Each experiment highlights the use of the subsystems such as the digital twin, motion capture system, human-physiological monitoring system, data collection system and robot control and interface systems. A highlight of this paper showcases a subsystem with the ability to monitor human physiological feedback during a human robot collaboration task.\",\n \"Title: ORBDeepOdometry - A Feature-Based Deep Learning Approach to Monocular Visual Odometry\\nYear: 2019\\n\\nAbstract: Visual Odometry (VO) is an application of computer vision which helps in autonomous navigation of Self-Driving vehicles, Robots etc. The odometry pose of the vehicle can be estimated using the consecutive frames based on monocular or stereo camera setup mounted on the vehicle. The Simultaneous Localization and Mapping (SLAM) based approaches have shown phenomenal results in predicting the vehicle odometry. Deep Learning based approaches are emerging in the field of computer vision and are outperforming other classic algorithms. But, visual odometry is one of the field where deep learning approaches have not yet been exploited largely. This paper proposes the use of Deep Learning based pipeline approach to solve the problem of visual odometry. The paper boosts the performance of deep learning approach by extracting quite more features before training the network. This paper proposes the use of ORB based feature extractor along with Convolutional Neural Network based dimensionality reduction and stacking multiple deep LSTM's for modelling the sequential data. In this case, the KITTI vision Benchmark dataset is used to model the network. The accuracy of the network is examined by calculating the error between the predicted odometry output and the ground truth odometry output. The results are compared with different Convolutional Neural Network (CNN) architectures proposed for the same task. The average translation error from the proposed system is 11.99% and the average rotational error from the proposed system is 0.0462 degrees per meter.\",\n \"Title: A Low-Cost Search-and-Rescue Drone for Near Real-Time Detection of Missing Persons\\nYear: 2019\\n\\nAbstract: In this work, an unmanned aerial system is implemented to search an outdoor area for an injured or missing person (subject) without requiring a connection to a ground operator or control station. The system detects subjects using exclusively on-board hardware as it traverses a predefined search path, with each implementation envisioned as a single element of a larger swarm of identical search drones. Imagery is streamed from a camera to an Odroid single-board computer, which prepares the data for inference by a Neural Compute Stick vision accelerator. A single-class TinyYolo network, trained on the Okutama-Action dataset and an original Albatross dataset, is utilized to detect subjects in the prepared frames. The detection apparatus is mounted on a drone and field tests validate the system feasibility and efficacy.\",\n \"Title: Smart Walker V: Implementation of RTAB-Map Algorithm\\nYear: 2019\\n\\nAbstract: Autonomous Navigation has been a field of major attraction to a large number of robotics enthusiasts all around the globe. Smart walker, a robot designed for assisting patients under intensive care, requires this exceptional add-on in order to have a better sense of the surrounding, captured through the RGB and depth sensor available on board. This paper addresses the navigation and mapping problem through a graph-based SLAM technique knows as Real-Time Appearance-based Mapping (RTAB-Map), which uses an interesting approach to map an area with the help of loop closures, and provides a number of visual feature tracking methods that can be used to detect the loop closures. The software stack on the Smart Walker has been built around ROS (Robot Operating System), and the necessary sensor, odometry and transformation messages have been configured accordingly, based on the onboard sensors and actuators attached to the Smart Walker. This paper discusses the implementation of RTAB-Map algorithm on the Smart Walker and steps involved in collecting a custom dataset. The approach also involves comparing the performance of visual feature tracking methods available in RTAB-Map algorithm on a standard dataset and on the custom dataset, based on non-statistical aspects in order to implement the right set of features for indoor use of the Smart Walker.\",\n \"Title: Low Computational Complexity Classifier Based On The Maximum Relative Global Peak For The Classification Of Eog Signals\\nYear: 2017\\n\\nAbstract: In this paper, a new low computational complexity machine learning classifier is developed to detect eye movements from an Electrooculography (EOG) signal. The proposed classier is based on finding the maximum relative global peak of a set of signals that are decomposed from the original EOG signals. Unlike many other classifiers, the proposed classifier does not depend on threshold signal levels or spectrum analysis of the EOG signals which require nonlinear and complex operations. The proposed classifier uses four predefined functions which are divided into two groups to distinguish between the horizontal and vertical eye movements. The new proposed classifier can be used for on low powerful boards because it does not require high speed processors where it needs to calculate only one optimum parameter that maximizes the global accuracy. The performance of the proposed classifier is better and faster by 40% than the SVM classifier. In addition, there is a misclassification between two classes only rather than three classes.\",\n \"Title: Learning Robotic Manipulation Tasks via Task Progress Based Gaussian Reward and Loss Adjusted Exploration\\nYear: 2022\\n\\nAbstract: Multi-step manipulation tasks in unstructured environments are extremely challenging for a robot to learn. Such tasks interlace high-level reasoning that consists of the expected states that can be attained to achieve an overall task and low-level reasoning that decides what actions will yield these states. We propose a model-free deep reinforcement learning method to learn multi-step manipulation tasks. We introduce a Robotic Manipulation Network (RoManNet)\\n<sup xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">1</sup>\\n, which is a vision-based model architecture, to learn the action-value functions and predict manipulation action candidates. We define a Task Progress based Gaussian (TPG) reward function that computes the reward based on actions that lead to successful motion primitives and progress towards the overall task goal. To balance the ratio of exploration/exploitation, we introduce a Loss Adjusted Exploration (LAE) policy that determines actions from the action candidates according to the Boltzmann distribution of loss estimates. We demonstrate the effectiveness of our approach by training RoManNet to learn several challenging multi-step robotic manipulation tasks in both simulation and real-world. Experimental results show that our method outperforms the existing methods and achieves state-of-the-art performance in terms of success rate and action efficiency. The ablation studies show that TPG and LAE are especially beneficial for tasks like multiple block stacking.\",\n \"Title: Learning Multi-step Robotic Manipulation Policies from Visual Observation of Scene and Q-value Predictions of Previous Action\\nYear: 2022\\n\\nAbstract: In this work, we focus on multi-step manipulation tasks that involve long-horizon planning and considers progress reversal. Such tasks interlace high-level reasoning that consists of the expected states that can be attained to achieve an overall task and low-level reasoning that decides what actions will yield these states. We propose a sample efficient Previous Action Conditioned Robotic Manipulation Network (PAC-RoManNet) to learn the action-value functions and predict manipulation action candidates from visual observation of the scene and action-value predictions of the previous action. We define a Task Progress based Gaussian (TPG) reward function that computes the reward based on actions that lead to successful motion primitives and progress towards the overall task goal. To balance the ratio of exploration/exploitation, we introduce a Loss Adjusted Exploration (LAE) policy that determines actions from the action candidates according to the Boltzmann distribution of loss estimates. We demonstrate the effectiveness of our approach by training PAC-RoManNet to learn several challenging multi-step robotic manipulation tasks in both simulation and real-world. Experimental results show that our method outperforms the existing methods and achieves state-of-the-art performance in terms of success rate and action efficiency. The ablation studies show that TPG and LAE are especially beneficial for tasks like multiple block stacking. Additional experiments on Ravens-10 benchmark tasks suggest good generalizability of the proposed PAC-RoManNet.\",\n \"Title: System Integration of a Tour Guide Robot\\nYear: 2022\\n\\nAbstract: In today’s world, people visit many attractive places. On such an occasion, It is of utmost importance to be accompanied by a tour guide, who is known to explain about the cultural and historical importance of places. Therefore, a human guide is necessary to provide tours for a group of visitors. However, Human tour guides might face tiredness, distraction, and the effects of repetitive tasks while providing tour service to visitors. Robots eliminate these problems and can provide tour consistently until it drains its battery. This experiment introduces a tour-guide robot that can navigate autonomously in a known map of a given place and at the same time interact with people. The environment is equipped with artificial landmarks. Each landmark provides information about that specific region. An Animated avatar is simulated on the screen. IBM Watson provides voice recognition and text-to-speech services for human-robot interaction. The experimental results show that the robot takes average time of 10000 seconds to provide a tour. TEB and DWA local planner are compared by allowing the robot to autonomously maneuver the environment for 9 trials which is tabulated in section V.\",\n \"Title: iOS Based Pose Estimation and Gesture Recognition for Robot Manipulation\\nYear: 2022\\n\\nAbstract: Interfacing between robots and humans has come a long way in the past few years, and new methods for smart, robust interaction are needed. Typically, a technician has to program a routine for a robot in order for the robot to be useful. This puts up a significant barrier to entry into the field of automating tasks using robots—not only is a technician and a computer required, but the robot is not adaptive to the immediate needs of the user. The robot is only capable of executing a pre-determined task and for any change to be made the entire system needs to be paused. This project seeks to bridge the gap between user and robot interface, creating an easy-to-use system that allows for adaptive robot control. Using a combination of computer vision and a monocular camera system and integrated LiDAR sensor on an iPhone, gesture recognition and pose estimation was conducted within an independent system to control the Baxter humanoid robot. The gathered data was sent wirelessly to the robot to be interpreted and then replay actions performed by the user.\",\n \"Title: Low Cost Real Time Location Tracking with Ultra-Wideband\\nYear: 2022\\n\\nAbstract: An emerging technology for indoor localization is ultra wide-band, also known as UWB. UWB has been making waves as a system that can be both secure and function as an “indoor GPS The proliferation of UWB is underway and soon it will be as ubiquitous as Bluetooth or Wi-Fi. With this in mind, the benchmarking of the DWM3000EVB module in an Ultra Wideband Real Time Locating System is the goal of this research. The UWB RTLS created is a three anchor - one tag system that can calculate position just under 100 Hz and has an average accuracy of 5 centimeters.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":67,"string":"67"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":82,"string":"82"}}},{"rowIdx":83,"cells":{"question_id":{"kind":"string","value":"Yuanwei Liu"},"question":{"kind":"string","value":"Generate an abstract for the title \"Matching With Peer Effects for Context-Aware Resource Allocation in D2D Communications\" using the following items: context-aware, resource allocation, device-to-device communications, matching theory, optimization problem."},"answer":{"kind":"string","value":"In this letter, we investigate the context-aware resource allocation for device-to-device communications accounting for the quality-of-service requirements and priorities of different applications based on users’ requests. We formulate a context-aware optimization problem and implement the matching theory to solve the problem. We propose a novel algorithm where the device-to-device user equipments and resource blocks act as two opposite sets of players and interact with each other to obtain the optimal matching. We analytically prove that the algorithm converges to a two-sided exchange stability within limited number of swap operations. We also demonstrate that the proposed algorithm significantly outperforms the context-unaware resource allocation algorithm by around 62.2%."},"correct_answer":{"kind":"string","value":"In this letter, we investigate the context-aware resource allocation for device-to-device communications accounting for the quality-of-service requirements and priorities of different applications based on users’ requests. We formulate a context-aware optimization problem and implement the matching theory to solve the problem. We propose a novel algorithm where the device-to-device user equipments and resource blocks act as two opposite sets of players and interact with each other to obtain the optimal matching. We analytically prove that the algorithm converges to a two-sided exchange stability within limited number of swap operations. We also demonstrate that the proposed algorithm significantly outperforms the context-unaware resource allocation algorithm by around 62.2%."},"documents":{"kind":"list like","value":["Title: Automatic game AI design by the use of UCT for Dead-End\nYear: 2010\n\nAbstract: Video game AI aims at generating an intelligent game opponent which is to compete with player, so game AI design plays an important role in the development of game. Nowadays, most of the game AI is implemented by FSM. But this mechanism has some drawbacks, so we need a mechanism to design game AI automatically instead of FSM. The process of automatic game AI design by UCT is introduced in this paper. In this process, we only take the meta-rules into consideration, while those many complicated detail knowledge is acquired by simulation. Here we propose the approach of UCT-controlled NPC based on CI (computational intelligence). However, this approach will consume lots of computational resources, and the acquired knowledge cannot be stored. To solve this problem, we train Artificial Neural Network (ANN) to make it reusable. The whole design process is validated on the Test-Bed of the game Dead-End. We conclude that from both the simplification of implementation and the reusability, this process outperforms FSM.","Title: Relay Selection for Security Enhancement in Cognitive Relay Networks\nYear: 2015\n\nAbstract: This letter proposes several relay selection policies for secure communication in cognitive decode-and-forward relay networks, where a pair of cognitive relays is opportunistically selected for security protection against eavesdropping. The first relay transmits the secrecy information to the destination, and the second relay, as a friendly jammer, transmits the jamming signal to confound the eavesdropper. We present new exact closed-form expressions for the secrecy outage probability. Our analysis and simulation results strongly support our conclusion that the proposed relay selection policies can enhance the performance of secure cognitive radio. We also confirm that the error floor phenomenon is created in the absence of jamming.","Title: Wireless Energy Harvesting and Spectrum Sharing in Cognitive Radio\nYear: 2014\n\nAbstract: A wireless energy harvesting protocol is proposed for a decode-and-forward relay- assisted secondary user (SU) network in a cognitive spectrum sharing paradigm. An expression for the outage probability of the relay-assisted cognitive network is derived subject to the following power constraints: 1) the maximum power that the source and the relay in the SU network can transmit from the harvested energy, 2) the peak interference power from the source and the relay in the SU network at the primary user (PU) network, and 3) the interference power of the PU network at the relay-assisted SU network. The results show that as the energy harvesting conversion efficiency improves, the relay- assisted network with the proposed wireless energy harvesting protocol can operate with outage probabilities below 20% for some practical applications.","Title: Two-way relaying networks with wireless power transfer: Policies design and throughput analysis\nYear: 2014\n\nAbstract: This paper exploits an amplify-and-forward (AF) two-way relaying network (TWRN), where an energy constrained relay node harvests energy with wireless power transfer. Two bidirectional protocols, multiple access broadcast (MABC) protocol and time division broadcast (TDBC) protocol, are considered. Three wireless power transfer policies, namely, dual-source (DS) power transfer; single-fixed-source (SFS) power transfer; and single-best-source (SBS) power transfer are proposed and well-designed based on time switching receiver architecture. We derive analytical expressions to determine the throughput both for delay-limited transmission and delay-tolerant transmission. Numerical results corroborate our analysis and show that MABC protocol achieves a higher throughput than TDBC protocol. An important observation is that SBS policy offers a good tradeoff between throughput and power.","Title: Wireless Energy Harvesting in a Cognitive Relay Network.\nYear: 2016\n\nAbstract: Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with multiple primary user (PU) transceivers. In this protocol, the secondary nodes can harvest energy from the primary network (PN) while sharing the licensed spectrum ...","Title: Secure D2D Communication in Large-Scale Cognitive Cellular Networks: A Wireless Power Transfer Model.\nYear: 2016\n\nAbstract: In this paper, we investigate secure device-to-device (D2D) communication in energy harvesting large-scale cognitive cellular networks. The energy constrained D2D transmitter harvests energy from multiantenna equipped power beacons (PBs), and communicates with the corresponding receiver using the spectrum of the primary base stations (BSs). We introduce a power transfer model and an information si...","Title: Throughput Analysis of Wireless Powered Cognitive Radio Networks with Compressive Sensing and Matrix Completion.\nYear: 2016\n\nAbstract: In this paper, we consider a cognitive radio network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure is proposed for the considered network. A wireless power transfer (WPT) model and a compressive spectrum sensing model are introduced. In the WPT model, a new WPT scheme is proposed, and the closed-form expressions for the power outage probability are derived. In compressive spectrum sensing model, two scenarios are considered: 1) Single SU, and 2) Multiple SUs. In the single SU scenario, in order to reduce the energy consumption at the SU, compressive sensing technique which enables sub-Nyquist sampling is utilized. In the multiple SUs scenario, cooperative spectrum sensing (CSS) is performed with adopting low-rank matrix completion technique to obtain the complete matrix at the fusion center. Throughput optimizations of the secondary network are formulated into two linear constrained problems, which aim to maximize the throughput of single SU and the CSS networks, respectively. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power. Simulation results show that: 1) Multiple SUs scenario can achieve lower power outage probability than single SU scenario; and 2) The optimal throughput can be improved by implementing compressive spectrum sensing in the proposed frame structure design.","Title: Application of Non-orthogonal Multiple Access in LTE and 5G Networks.\nYear: 2017\n\nAbstract: As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP LTE and is envisioned to be an essential component of 5G mobile networks. The key feature of NOMA is to serve multiple users at the same time/frequency/ code, but with different power levels, which yields a significant spectral efficiency gain over conventional orthogonal MA. The article provides a systematic treatment of this newly emerging technology, from its combination with MIMO technologies to cooperative NOMA, as well as the interplay between NOMA and cognitive radio. This article also reviews the state of the art in the standardization activities concerning the implementation of NOMA in LTE and 5G networks.","Title: Improvements Of Robot Positioning Accuracy And Drilling Perpendicularity For Autonomous Drilling Robot System\nYear: 2015\n\nAbstract: The low accuracy of Autonomous Drilling Robot System (ADRS) has precluded their usage in aircraft assembly. Aiming at improving the accuracy of ADRS, three efforts are made in this paper. Firstly, a novel surface normal measurement and attitude adjusting method are proposed to guarantee the perpendicularity of holes. Secondly, an improvement compensation method is made for absolute positioning accuracy of industrial robot by using Gauss-Newton method. Thirdly, during the calibration of tool center point(TCP), which is one of the key technologies of offline programming control system, two balls are used in this method to solve the problem of low accuracy and inefficiency of traditional method using pointed end. Finally, both simulations and experiments are conducted to test the effect of the improvements and the results prove the improvements are effective.","Title: Cooperative non-orthogonal multiple access in 5G systems with SWIPT\nYear: 2015\n\nAbstract: In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) is investigated. A new cooperative SWIPT NOMA protocol is proposed in which near NOMA users which arc close to the source act as energy harvesting relays to help far NOMA users. By assuming that all users are spatially randomly located in the network, new analytical expressions for outage probability are derived both for the near and far users, in order to characterize the performance of the proposed protocol. The diversity of both the near and far users is analyzed to demonstrate that the use of SWIPT will not jeopardize the diversity order compared to the conventional NOMA. Numerical results are also provided to verify the accuracy of the developed analytical results.","Title: Throughput Analysis for Compressive Spectrum Sensing with Wireless Power Transfer.\nYear: 2015\n\nAbstract: In this paper, we consider a cognitive radio (CR) network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure which includes four time slots, namely, energy harvesting, spectrum sensing, energy harvesting and data transmission is proposed. In the energy harvesting slot, a new wireless power transfer (WPT) scheme in a bounded power transfer model is proposed to enable power SUs wirelessly. Closed-form expressions for the power outage probability of the proposed WPT scheme are derived. In the spectrum sensing slot, we propose to utilize the compressive sensing (CS) technique which enables sub-Nyquist sampling to further reduce the energy consumption at SUs. Throughput of the secondary network with the proposed frame structure is formulated into a nonlinear constraint problem. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power.","Title: Fairness of User Clustering in MIMO Non-Orthogonal Multiple Access Systems.\nYear: 2016\n\nAbstract: In this letter, a downlink multiple-input-multiple-output non-orthogonal multiple access scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this optimization problem, three sub-optimal algorithms, namely, top-down A, top-down B, and bottom up, are proposed to realize the different tradeoffs of complexity and throughput of the worst user. In addition, for each given user clustering case, we optimize the power allocation coefficients for the users in each cluster by adopting a bisection search-based algorithm. Numerical results show that the proposed algorithms can lower the complexity with an acceptable degradation on the throughput compared with the exhaustive search method. It is worth noting that the top-down B algorithm can achieve a good tradeoff between the complexity and the throughput among the three proposed algorithms.","Title: Physical layer security for 5G non-orthogonal multiple access in large-scale networks\nYear: 2016\n\nAbstract: In this paper, the physical layer security of applying non-orthogonal multiple access (NOMA) in large-scale networks is investigated. In the considered scenario, both the NOMA users and eavesdroppers are spatially randomly deployed. A protected zone around the source node is adopted to enhance the security of a random network. In order to characterize the secrecy performance of the considered scenario, new exact and asymptotic expressions for the security outage probability are derived. These analytical results demonstrate that the secrecy diversity order is m, which is determined by the user with poor channel condition. Monte Carlo simulations are provided to verify the derived analytical results. Furthermore, it is also confirmed that the secure performance of the NOMA networks can be improved by either enlarging the scope of the protected zone or reducing the scope of the user zone.","Title: Two-way relay networks with wireless power transfer: design and performance analysis.\nYear: 2016\n\nAbstract: This study considers amplify-and-forward two-way relay networks, where an energy constrained relay node harvests energy from the received radio-frequency signal. Based on time switching receiver, they separate the energy harvesting (EH) phase and the information processing (IP) phase in time. In the EH phase, three practical wireless power transfer policies are proposed: (i) dual-source (DS) power...","Title: Many-to-Many Matching With Externalities for Device-to-Device Communications\nYear: 2017\n\nAbstract: In this letter, we aim to solve the resource allocation problem for device-to-device (D2D) communications underlaying cellular networks. Particularly, multiple D2D pairs are allowed to reuse the same resource block (RB), and one D2D pair is allowed to use the spectrum of multiple RBs. Our objective is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise ratio constraints for both D2D and cellular user equipments. In order to solve this non-deterministic polynomial-time hard optimization problem, we propose a novel algorithm for obtaining a sub-optimal solution based on the many-to-many two-sided matching game with externalities. To characterize the properties of the proposed algorithm, we prove that it converges to the two-sided exchange stability within a limited number of iterations. Additionally, simulation results show that the proposed algorithm can achieve the near-optimal system sum rate and significantly outperforms a one-to-one matching algorithm.","Title: Enhancing the Physical Layer Security of Non-orthogonal Multiple Access in Large-Scale Networks.\nYear: 2017\n\nAbstract: This paper investigates the physical layer security of non-orthogonal multiple access (NOMA) in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered, where the base station (BS) communicates with randomly distributed NOMA users. In the single-antenna scenario, we adopt a protected zone around the BS to establish an eavesdropper-exclusion area with the aid of careful channel ordering of the NOMA users. In the multiple-antenna scenario, artificial noise is generated at the BS for further improving the security of a beamforming-aided system. In order to characterize the secrecy performance, we derive new exact expressions of the security outage probability for both single-antenna and multiple-antenna aided scenarios. For the single-antenna scenario, we perform secrecy diversity order analysis of the selected user pair. The analytical results derived demonstrate that the secrecy diversity order is determined by the specific user having the worse channel condition among the selected user pair. For the multiple-antenna scenario, we derive the asymptotic secrecy outage probability, when the number of transmit antennas tends to infinity. Monte Carlo simulations are provided for verifying the analytical results derived and to show that: 1) the security performance of the NOMA networks can be improved by invoking the protected zone and by generating artificial noise at the BS and 2) the asymptotic secrecy outage probability is close to the exact secrecy outage probability.","Title: NOMA-Based D2D Communications: Towards 5G.\nYear: 2016\n\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA)-based device-to-device (D2D) communications framework is proposed. A major novelty of the proposed framework is that it introduces the new concept of \"D2D group\" which utilizes NOMA transmission, enabling one D2D transmitter to communicate with multiple D2D receivers simultaneously. Based on the considered framework, a resource allocation optimization problem is formulated, where multiple D2D groups are allowed to reuse the same subchannel. The objective of this work is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise (SINR) constraints of both D2D and traditional cellular users. Note that the formulated problem is non-deterministic polynomial-time (NP) hard in nature, thus a novel resource allocation algorithm based on the many-to-one two-sided matching theory is proposed for obtaining a suboptimal solution. It is proved that the proposed algorithm converges to a stable state within limited number of iterations. Numerical results illustrate that: i) the proposed algorithm is an effective approach for obtaining near-optimal performance with acceptable complexity; and ii) the proposed NOMA-based D2D framework is capable of achieving promising gains over traditional orthogonal multiple access (OMA)-based D2D framework.","Title: Wireless Powered Cognitive Radio Networks With Compressive Sensing and Matrix Completion\nYear: 2017\n\nAbstract: In this paper, we consider cognitive radio networks in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons. A new frame structure is proposed for the considered networks. In the considered network, a wireless power transfer model is proposed, and the closed-form expressions for the power outage probability are derived. In addition, in order to...","Title: Performance Analysis of NOMA With Fixed Gain Relaying Over Nakagami-m Fading Channels.\nYear: 2018\n\nAbstract: This paper studies the application of cooperative techniques for non-orthogonal multiple access (NOMA). More particularly, the fixed gain amplify-and-forward (AF) relaying with NOMA is investigated over Nakagami-m fading channels. Two scenarios are considered insightfully: 1) the first scenario is that the base station (BS) intends to communicate with multiple users through the assistance of AF relaying, where the direct links are existent between the BS and users and 2) the second scenario is that the AF relaying is inexistent between the BS and users. To characterize the performance of the considered scenarios, new closed-form expressions for both exact and asymptomatic outage probabilities are derived. Based on the analytical results, the diversity orders achieved by the users are obtained. For the first and second scenarios, the diversity order for the nth user are mu(n+ 1) and mu n, respectively. Simulation results unveil that NOMA is capable of outperforming orthogonal multiple access (OMA) in terms of outage probability and system throughput. It is also worth noting that NOMA can provide better fairness compared with conventional OMA. By comparing the two scenarios, cooperative NOMA scenario can provide better outage performance relative to the second scenario.","Title: Non-orthogonal Multiple Access in Large-Scale Heterogeneous Networks.\nYear: 2017\n\nAbstract: In this paper, the potential benefits of applying non-orthogonal multiple access (NOMA) technique in K -tier hybrid heterogeneous networks (HetNets) is explored. A promising new transmission framework is proposed, in which NOMA is adopted in small cells and massive multiple-input multiple-output (MIMO) is employed in macro cells. For maximizing the biased average received power for mobile users, a...","Title: Optimal User Scheduling and Power Allocation for Millimeter Wave NOMA Systems.\nYear: 2018\n\nAbstract: This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mm-Wave) communications by exploiting beamforming, user scheduling, and power allocation. Random beamforming is invoked for reducing the feedback overhead of the considered system. A non-convex optimization problem for maximizing the sum rate is formulated, which is proved to be NP-hard. The branch...","Title: Modelling And Analysis Of Low-Power Wide-Area Networks\nYear: 2017\n\nAbstract: In this paper, we investigate the uplink transmission performance of low-power wide-area networks (LPWANs) with regards to coexisting radio modules using LoRa as an example. In doing so we adopt a new topology to model the network where the node locations of the network of focus (LoRa) follow a Poisson cluster process (PCP) while other coexisting interfering radio modules follow a Poisson point process (PPP). To characterize the performance of the proposed model as well as obtain insights, both analytical and closed-form approximated expressions for coverage probability are derived. Based on this, area spectrum efficiency, and energy efficiency are further characterized. These results demonstrate the degree to which the performance, with regard to the aforementioned metrics, is capable of being enhanced through varying the density of the deployment of LoRa nodes around each LoRa receiver. Moreover, simulation results unveil that an optimal value of active LoRa nodes in each cluster exists that maximizes area spectrum efficiency.","Title: Resource Allocation For Non-Orthogonal Multiple Access In Heterogeneous Networks\nYear: 2017\n\nAbstract: In this paper, novel resource allocation design is investigated for NOMA-enhanced heterogeneous networks (Het-Nets), where small cell base stations (SBSs) are enabled to communicate with multiple small cell users (SCUs) via the NOMA protocol. The resource allocation problem with the aim of maximizing the sum rate of SCUs is formulated as a many-to-one matching game. Due to the existence of co-channel interference, this game is shown to belong to a class of matching games with peer effects. To solve this game, we propose a novel distributed algorithm where the SBSs and resource blocks (RBs) can interact to decide their desired allocation. The proposed algorithm is proved to converge to a two-sided exchange-stable matching with much lower complexity compared to the centralized method. Simulation results unveil that: 1) The proposed algorithm closely approaches the global optimal solution by around 92.5% within a limited number of iterations; and 2) The developed NOMA-enhanced HetNets scheme achieves a higher sum rate of SCUs compared to the traditional OMA-based HetNets scheme.","Title: Joint Subchannel and Power Allocation for NOMA Enhanced D2D Communications.\nYear: 2017\n\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA) enhanced device-to-device (D2D) communication scheme is considered. Our objective is to maximize the system sum rate by optimizing subchannel and power allocation. We propose a novel solution that jointly assigns subchannels to D2D groups and allocates power to receivers in each D2D group. For the subchannel assignment, a novel algorithm...","Title: Nonorthogonal Multiple Access for 5G and Beyond.\nYear: 2018\n\nAbstract: Driven by the rapid escalation of the wireless capacity requirements imposed by advanced multimedia applications (e.g., ultrahigh-definition video, virtual reality, etc.), as well as the dramatically increasing demand for user access required for the Internet of Things (IoT), the fifth-generation (5G) networks face challenges in terms of supporting large-scale heterogeneous data traffic. Nonorthog...","Title: Spectrum Allocation and Power Control for Non-Orthogonal Multiple Access in HetNets.\nYear: 2017\n\nAbstract: In this paper, a novel resource allocation design is investigated for non-orthogonal multiple access (NOMA) enhanced heterogeneous networks (HetNets), where small cell base stations (SBSs) are capable of communicating with multiple small cell users (SCUs) via the NOMA protocol. With the aim of maximizing the sum rate of SCUs while taking the fairness issue into consideration, a joint problem of sp...","Title: Joint Pilot Allocation and Robust Transmission Design for Ultra-dense User-centric TDD C-RAN with Imperfect CSI.\nYear: 2018\n\nAbstract: This paper considers the unavailability of complete channel state information (CSI) in ultra-dense cloud radio access networks. The user-centric cluster is adopted to reduce the computational complexity, while the incomplete CSI is considered to reduce the heavy channel training overhead, where only large-scale inter-cluster CSI is available. Channel estimation for intra-cluster CSI is also consid...","Title: Uplink NOMA in Large-Scale Systems: Coverage and Physical Layer Security.\nYear: 2017\n\nAbstract: In this paper, the physical layer security of uplink non-orthogonal multiple access (NOMA) in large-scale networks is analyzed. An stochastic geometry approach is applied to derive new analytical expressions for the coverage probability and the effective secrecy throughput (EST) of the kth NOMA user, which may use a fixed or an adaptive transmission rate. We consider a protected zone around the legitimate terminals to establish an eavesdropper-exclusion area. We assume that the channel state information associated with eavesdroppers is not available at the base station. The impact of an imperfect successive interference cancellation is also taken into account in this work. Our analysis allows an easy selection of the wiretap code rates that maximizes the EST. In addition, our framework also allows an optimum selection of other system parameters like the transmit power or the eavesdropper-exclusion radius.","Title: Joint Pilot Allocation and Robust Beam-Vector Design for Ultra-Dense TDD C-RAN.\nYear: 2017\n\nAbstract: This paper deals with the unavailability of full CSI in ultra-dense user-centric TDD C-RAN. To reduce the channel training overhead, we consider the incomplete CSI case, where only large-scale inter-cluster CSI is available. Channel estimation for intra-cluster CSI is also considered, where we formulate a joint pilot allocation and user equipment (UE) selection problem to maximize the number of admitted UEs with fixed number of pilots. A novel pilot allocation algorithm is proposed by considering the multi-UE pilot interference. Then, we consider robust beam-vector optimization problem subject to UEs' data rate requirements and fronthaul capacity constraints, where the channel estimation error and incomplete inter-cluster CSI are considered. Simulation results demonstrate its superiority over the existing algorithms.","Title: Modeling and Analysis of NOMA Enabled CRAN with Cluster Point Process.\nYear: 2017\n\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA)-enabled framework for cloud-radio access networks (CRANs) is proposed. In this framework, two users are scheduled in the same resources according to NOMA; however the performance of cell-edge users is enhanced by means of coordinating beamforming. Stochastic geometry is invoked for modeling the proposed framework, where the positions of BSs follow a cluster point process. In an effort to characterize the performance of the proposed framework, simple expressions in terms of outage probability are derived for both nearby users and the cell-edge users. It is analytically demonstrated that the average beamforming gain is a liner function with respect to the number of cooperating base stations. Numerical results verify the accuracy of analysis and reveal that the proposed framework is capable of greatly enhancing the performance of cell-edge users.","Title: User Selection and Power Allocation for mmWave-NOMA Networks.\nYear: 2017\n\nAbstract: This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mmWave) communication with beamforming, user selection and power allocation. To overcome the burden of feedback, random beamforming to mmWave NOMA systems is considered. We then formulate an optimization problem to maximize the sum rate of the proposed mmWave NOMA systems, which is nonconvex. To solve the challenging problem, we invoke the branch and bound (BB) technique to develop an optimal power allocation algorithm. Then a low complexity suboptimal algorithm based on matching theory is proposed to realize user selection. Simulation results are provided for validating the effectiveness of the proposed algorithms and to show that the sum rate performance of the mmWave NOMA systems can be substantially improved by the proposed algorithms compared to the conventional mmWave orthogonal multiple access (OMA) systems.","Title: Full/Half-Duplex Relay Selection for Cooperative NOMA Networks.\nYear: 2017\n\nAbstract: This paper investigates the impact of relay selection (RS) on the performance of cooperative non-orthogonal multiple access (NOMA), where relays are capable of working in either full-duplex (FD) or half-duplex (HD) mode. The locations of relays considered in the networks are modeled using stochastic geometry. The single-stage relay selection (SRS) scheme is proposed. In order to characterize the performance of SRS scheme, new closed-form expressions for both exact and asymptotic outage probabilities are derived. Based on the analytical results, the diversity orders achieved by the SRS scheme for FD/HD cooperative NOMA are obtained. It is confirmed that the FD-based SRS schemes obtain a zero diversity order, while the HD-based RS is capable of achieving a diversity order of K. Simulation results show that the outage performance of FD-based RS scheme outperforms HD-based RS scheme in the low signal-to-noise radio (SNR) region rather than in the high SNR region.","Title: Training Based DOA Estimation in Hybrid mmWave Massive MIMO Systems.\nYear: 2017\n\nAbstract: This paper proposes a novel direction of arrival (DOA) estimation for hybrid millimeter wave (mmWave) massive MIMO systems with the uniform planar array (UPA) at base station (BS). To explore the physical characteristics of antenna array in mmWave systems, the parameters of each channel path are decomposed into the DOA information and the channel gain information. We first estimate the initial DOAs of each uplink path through the two dimension discrete Fourier transform (2D-DFT) efficiently, and then the estimation accuracy can be further enhanced via the angle rotation technique. To examine the estimation performance, we derive the theoretical bounds of the mean squared error (MSE) performance of the DOA estimation in high signal-to-noise ratio (SNR) region. Simulation results are provided to corroborate the proposed studies, and show that the proposed DOA estimation method is close to the theoretical MSE performance.","Title: Modeling and Analysis of D2D Millimeter-Wave Networks With Poisson Cluster Processes.\nYear: 2018\n\nAbstract: This paper investigates the performance of millimeter wave (mmWave) communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process. In each cluster, devices are equipped with multiple antennas, and the active D2D transmitter (D2D-Tx) utilizes mmWave to serve one of the proximate D2D receivers. Specifically, we introduce three...","Title: Cooperative Communications With Wireless Energy Harvesting Over Nakagami-m Fading Channels.\nYear: 2017\n\nAbstract: In this paper, a dual-hop decode-to-forward cooperative system is considered where multiple relays are with finite energy storage and can harvest energy from the destination. In our analysis, the relays are spatially randomly located with invoking stochastic geometry. In an effort to improve spectral efficiency, an optimal source-relay link scheme is employed. Assuming Nakagami-m fading, two diffe...","Title: Exploiting Full/Half-Duplex User Relaying in NOMA Systems.\nYear: 2018\n\nAbstract: In this paper, a novel cooperative non-orthogonal multiple access (NOMA) system is proposed, where one near user is employed as decode-and-forward relaying switching between full-duplex (FD) and half-duplex (HD) mode to help a far user. Two representative cooperative relaying scenarios are investigated insightfully. The first scenario is that no direct link exists between the base station (BS) and...","Title: User Association and Resource Allocation in Unified NOMA Enabled Heterogeneous Ultra Dense Networks\nYear: 2018\n\nAbstract: Heterogeneous ultra dense networks (HUDNs) and non-orthogonal multiple access (NOMA) have been identified as two proposing techniques for 5G mobile communication systems due to their great capabilities to enhance spectrum efficiency. This article investigates the application of NOMA techniques in HUDNs to support massive connectivity in 5G systems. In particular, a unified NOMA framework is propos...","Title: Toward Cross-Layer Design for Non-Orthogonal Multiple Access: A Quality-of-Experience Perspective.\nYear: 2018\n\nAbstract: Recent years have seen a proliferation in versatile mobile devices and an upsurge in the growth of data-consuming application services. Orthogonal multiple access technologies in today's mobile systems are inefficient in the presence of such massive connectivity and traffic demands. In this regard, non-orthogonal multiple access has been advocated by the research community to embrace unprecedented...","Title: Sparse Representation for Wireless Communications.\nYear: 2018\n\nAbstract: Sparse representation can efficiently model signals in different applications to facilitate processing. In this article, we will discuss various applications of sparse representation in wireless communications, with a focus on the most recent compressive sensing (CS)-enabled approaches. With the help of the sparsity property, CS is able to enhance the spectrum efficiency (SE) and energy efficiency (EE) of fifth-generation (5G) and Internet of Things (IoT) networks.","Title: Maximizing SINR for non-orthogonal multiple access with bounded channel uncertainties\nYear: 2017\n\nAbstract: This letter examines the robust beamforming design multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) downlink systems with imperfect channel state information (ICSI). Sparked by the worst-case performance optimization framework, we consider to maximize the minimum of received signal-to-interference-plus-noise ratios (SINRs) of users, which is not convex with regards of beamforming vectors. The formulated optimization problem is not convex so, to solve the challengeable problem, we first formulate a equivalent optimization problem based on semidefinite programming (SDP). By applying a rank one relaxation and a linear matrix inequality (LMI) the S-Procedure can be used, which leads to exploiting bisection algorithm in order to obtaining the robust optimal beamforming solution. Finally, simulation results demonstrate the proposed design.","Title: Sparse Representation for Wireless Communications: A Compressive Sensing Approach.\nYear: 2018\n\nAbstract: Sparse representation can efficiently model signals in different applications to facilitate processing. In this article, we will discuss various applications of sparse representation in wireless communications, with a focus on the most recent compressive sensing (CS)-enabled approaches. With the help of the sparsity property, CS is able to enhance the spectrum efficiency (SE) and energy efficiency...","Title: Modeling and Analysis of Clustered D2D Millimeter-Wave Communications\nYear: 2018\n\nAbstract: This paper investigates the performance of millimeter wave communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process. In each cluster, the active D2D receiver (D2D-Rx) utilizes mmWave to communicate with one of proximate D2D transmitters (D2D-Txs). More specifically, we introduce two serving D2D-TX selection scenarios: 1) Uniformly distributed D2D-Tx model; 2) Closest line-of-site (LOS) D2D-Tx model. Moreover, we derive new analytical expressions for the coverage probability and area spectral efficiency (ASE). Monte Carlo simulations are provided to corroborate the theoretical results and show that: 1) The coverage probability is mainly affected by the LOS-interference; and 2) There exists an optimum number of simultaneously active D2D-Txs in each cluster for maximizing ASE.","Title: Simultaneous Calibration of Hand-Eye Relationship, Robot-World Relationship and Robot Geometric Parameters with Stereo Vision.\nYear: 2016\n\nAbstract: Robot-world calibration and hand-eye calibration are fundamental steps for robots equipped with cameras. This problem is described as solving \"AX = YB\" equation. However, this problem usually interacts with robot calibration, because robot geometric parameters are not very precise. Therefore, we propose a novel calibration method which can calibrate hand-eye relationship, robot-world relationship and robot geometric parameters simultaneously. This method considers hand-eye relationship and robot-world relationship as another two axes of robot arm. Modified D-H convention is used to describe robot position and orientation and stereo cameras are used to measure positioning errors. In order to improve calibration accuracy, least square method is introduced to solve calibration equations. Simulation and implement prove that this overall calibration method is feasible.","Title: Multiple Antenna Aided NOMA in UAV Networks: A Stochastic Geometry Approach.\nYear: 2019\n\nAbstract: This paper investigates the multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) assisted unmanned aerial vehicles (UAVs) networks. By utilizing a stochastic geometry model, a new 3-D UAV framework for providing wireless service to randomly roaming NOMA users has been proposed. In an effort to evaluate the performance of the proposed framework, we derive analytical expressions for the outage probability and the ergodic rate of MIMO-NOMA enhanced UAV networks. We examine tractable upper bounds for the whole proposed framework, with deriving asymptotic results for scenarios that transmit power of interference sources being proportional or being fixed to the UAV. For obtaining more insights for the proposed framework, we investigate the diversity order and high signal-to-noise slope of MIMO-NOMA assisted UAV networks. Our results confirm that: 1) Outage probability of NOMA enhanced UAV networks is affected to a large extent by the targeted transmission rates and power allocation factors of NOMA users and 2) For the case that the interference power is proportional to the UAV power, there are error floors for the outage probabilities.","Title: Cache-enabled HetNets With Millimeter Wave Small Cells.\nYear: 2018\n\nAbstract: In this paper, we consider a novel cache-enabled heterogeneous network (HetNet), where macro base stations (BSs) with traditional sub-6 GHz are overlaid by dense millimeter wave (mmWave) pico BSs. These two-tier BSs, which are modeled as two independent homogeneous Poisson point processes, cache multimedia contents following the popularity rank. High-capacity backhauls are utilized between macro B...","Title: Spatially Random Relay Selection for Full/Half-Duplex Cooperative NOMA Networks.\nYear: 2018\n\nAbstract: This paper investigates the impact of relay selection (RS) on the performance of cooperative non-orthogonal multiple access (NOMA), where relays are capable of working in either full-duplex (FD) or half-duplex (HD) mode. A number of relays (i.e., K relays) are uniformly distributed within the disc. A pair of RS schemes are considered insightfully: 1) single-stage RS (SRS) scheme; and 2) two-stage ...","Title: Modeling and Analysis of Two-Way Relay Non-Orthogonal Multiple Access Systems.\nYear: 2019\n\nAbstract: A two-way relay non-orthogonal multiple access (TWR-NOMA) system is investigated, where two groups of NOMA users exchange messages with the aid of one half-duplex decode-and-forward relay. Since the signal-plus-interference-to-noise ratios of NOMA signals mainly depend on effective successive interference cancellation (SIC) schemes, imperfect SIC (ipSIC), and perfect SIC (pSIC) are taken into acco...","Title: QoE-Based Resource Allocation for Multi-Cell NOMA Networks.\nYear: 2018\n\nAbstract: Quality of experience (QoE) is an important indicator in the fifth generation (5G) wireless communication systems. For characterizing user-base station (BS) association, subchannel assignment, and power allocation, we investigate the resource allocation problem in multi-cell multicarrier non-orthogonal multiple access (MC-NOMA) networks. An optimization problem is formulated with the objective of ...","Title: A Unified Framework for Non-Orthogonal Multiple Access.\nYear: 2019\n\nAbstract: This paper proposes a unified framework of non-orthogonal multiple access (NOMA) networks. Stochastic geometry is employed to model the locations of spatially NOMA users. The proposed unified NOMA framework is capable of being applied to both code-domain NOMA (CD-NOMA) and power-domain NOMA (PD-NOMA). Since the detection of NOMA users mainly depend on efficient successive interference cancelation ...","Title: Joint Radio and Computational Resource Allocation for NOMA-Based Mobile Edge Computing in Heterogeneous Networks.\nYear: 2018\n\nAbstract: A joint radio and computational resource allocation problem is investigated for non-orthogonal multiple access (NOMA)-based mobile edge computing (MEC) in heterogeneous networks (HetNets). The aim is to minimize the energy consumption of all users under the task execution latency constraint with partial task offloading. Due to the non-convexity of the formulated problem, we propose an iterative al...","Title: Angle Domain Channel Estimation in Hybrid Millimeter Wave Massive MIMO Systems.\nYear: 2018\n\nAbstract: This paper proposes a novel direction-of-arrival (DOA)-aided channel estimation for a hybrid millimeter-wave (mm-wave) massive multiple-input multiple-output system with a uniform planar array at the base station. To explore the physical characteristics of the antenna array in mm-wave systems, the parameters of each channel path are decomposed into the DOA information and the channel gain informat...","Title: Trajectory tracking control method and experiment of AGV\nYear: 2016\n\nAbstract: Aiming at the trajectory tracking control of AGV in aeronautical manufacturing and automated warehouse, a novel trajectory tracking control method was proposed. Firstly, the kinematic model and trajectory tracking control model of AGV were established. After analysing the reversing problem of AGV in practical situation and the limitations of classic trajectory tracking control method, and based on the similarity between the forward mode and reversing mode of AGV, a novel trajectory tracking control rule was designed and its stability was proved. The trajectory tracking control rule had simpler, less amount of calculation and improved the flexibility and handling efficiency of AGV. Finally, the trajectory tracking control experiments of sinusoid and path consisting of segments and arcs were done on experimental platform. The experiment results verified that the trajectory tracking control method were effective and feasible. The method could meet the requirements of autonomous handing for AGV in aeronautical manufacturing and automated warehouse.","Title: A visual positioning and measurement system for robotic drilling\nYear: 2016\n\nAbstract: In order to increase drilling efficiency, it is necessary for robotic drilling system to take advantage of offline programming method to drill a large number of holes automatically. Vision measurement is needed to correct work piece position because of inconformity between actual object and mathematical models. This paper introduces a visual positioning and measurement system for robotic drilling. A calibration board is designed to obtain hand-eye relationship and four laser range sensors are used to measure surface normal. This paper also summarizes workflow of offline programming and correction methods for different parts. Experiments give the result of hand-eye relationship and prove the position accuracy of vision measurement.","Title: UAV Communications Based on Non-Orthogonal Multiple Access.\nYear: 2019\n\nAbstract: This article proposes a novel framework for UAV networks with massive access capability supported by NOMA. In order to better understand NOMA-enabled UAV networks, three case studies are carried out. We first provide performance evaluation of NOMA-enabled UAV networks by adopting stochastic geometry to model the positions of UAVs and ground users. Then we investigate the joint trajectory design and power allocation for static NOMA users based on a simplified 2D model of UAV flying around at fixed height. As a further advance, we demonstrate the UAV placement issue with the aid of machine learning techniques when the ground users are roaming and the UAVs are capable of adjusting their positions in three dimensions accordingly. With these case studies, we can comprehensively understand the UAV systems from fundamental theory to practical implementation.","Title: Multi-Pair Two-Way Massive MIMO Relaying with Hardware Impairments over Rician Fading Channels\nYear: 2018\n\nAbstract: We consider a multi-pair two-way massive multiple-input multiple-out (MIMO) relaying system over Rician fading channels, where multi-pair users exchange their information via the amplify-and-forward (AF) relaying equipped with large number of antenna arrays. Hardware impairments at the relay and imperfect channel state information (CSI) are taken into account. More specifically, we derive a new linear minimum mean- square error (MMSE) channel estimator for the proposed system. It is demonstrated that normalized mean square error (NMSE) is a constant when the pilot power grows to infinity. Moreover, the asymptotic spectral efficiency with maximum ratio processing is presented in closed-form and the power scaling laws are analyzed. Simulation results indicates that massive MIMO is capable of compensating the loss caused by hardware impairments, estimation error and Rician fading.","Title: Outage Performance of Cooperative NOMA Networks with Hardware Impairments.\nYear: 2018\n\nAbstract: We investigate the outage performance of cooperative non-orthogonal multiple access (NOMA) networks with transceiver hardware impairments, where the estimated channel state information and alpha - mu fading channels are considered. Closed-form expressions for the outage probability of cooperative NOMA networks are derived for two representative scenarios. The first scenario is the base station (BS) directly communicates with NOMA users. The second scenario is BS communicates with NOMA users via the AF relaying. The diversity orders are presented for the two scenarios. It reveals that there is an error floor for the outage probability due to the distortion noise and estimation error.","Title: Q-Learning for Content Placement in Wireless Cooperative Caching.\nYear: 2018\n\nAbstract: Caching during off-peak times can bring popular contents closer to users, and hence improves quality of experience (QoE) of users in wireless networks. We formulate an optimization problem of cooperative content caching, with the aim of maximizing the sum mean opinion score (MOS) of all users in the network. To solve the challenging content caching problem, we cluster users by global kmeans (GKM), based on content popularity. For improving the effectiveness of caching, we propose a low complexity epsilon-greedy Q-learning based content caching algorithm which obtains near optimal solution. To characterize the performance of the proposed cooperative caching algorithms, sum MOS of users is used to define the reward function in Q-learning. The proposed Q-learning algorithm is capable of assisting the network to efficiently utilize the caching resource of the BSs. Simulation results reveal that: The proposed low complexity epsilon-greedy Q-learning based content caching algorithm achieves a near-optimal performance, and is capable of outperforming GKM based caching.","Title: A Unified Spatial Framework for Clustered UAV Networks Based on Stochastic Geometry.\nYear: 2018\n\nAbstract: To evaluate the system-level performance of clustered unmanned aerial vehicle (UAV) networks, we apply stochastic geometry in order to establish a tractable analytical framework. The users' locations are modeled as Poisson cluster processes (PCPs) and the UAVs are assumed to hover above cluster centers at a fixed altitude. In order to enhance the generality of the analysis, two typical patterns of PCPs, namely Thomas cluster process and Matern cluster process, are analyzed. Based on this spatial framework, a unified expression for the coverage probability is derived, for both millimeter wave (mmWave) and sub-6 GHz scenarios. Theoretical and numerical results demonstrate that mmWave outperforms sub-6 GHz, and an optimal altitude of UAVs exists, which maximizes the coverage probability. This result indicates that in most cases UAVs perform better than traditional terrestrial base stations, due to their mobility.","Title: Mode Selection Between Index Coding and Superposition Coding in Cache-Based NOMA Networks\nYear: 2019\n\nAbstract: By analytically showing that index coding (IC) is more power efficient than superposition coding (SC) when appropriate caching contents are available for a pair of users, we propose a sub-optimal joint user clustering and power allocation scheme for a single-cell downlink non-orthogonal multiple access network with caching memory at the receivers that alternate between IC and SC. Simulation studies demonstrate that the proposed scheme significantly reduces the transmission power when compared with the benchmark scheme that only allows SC.","Title: Non-Orthogonal Multiple Access in Massive MIMO Aided Heterogeneous Networks.\nYear: 2016\n\nAbstract: In this paper, the application of non-orthogonal multiple access (NOMA) into K-tier heterogeneous networks (HetNets) is investigated. A new promising transmission framework is proposed, in which massive multiple-input multiple-output (MIMO) is employed in macro cells and NOMA is adopted in small cells. For maximizing the biased average received power at mobile users, a massive MIMO and NOMA based user association scheme is developed. In an effort to evaluate the performance of the proposed framework, analytical expressions for the spectrum efficiency of each tier are derived using stochastic geometry. Simulation results are presented to verify the accuracy of the proposed analytical derivations and confirm that NOMA is capable of enhancing the spectrum efficiency of the network compared to the orthogonal multiple access (OMA) based HetNets.","Title: Outage Performance Of Full/Half-Duplex User Relaying In Noma Systems\nYear: 2017\n\nAbstract: This paper investigates the performance of cooperative non-orthogonal multiple access (NOMA) systems, where one near user works as a decode-and-forward (DF) full-duplex (FD) or half-duplex (HD) relaying to help far user. Two cooperative relay scenarios are considered insightfully. 1) The first scenario is that no direct link exists between the base station (BS) and the far user; and 2) The second scenario is that direct link exists between the BS and the far user. To characterize the performance of FD NOMA in two considered scenarios, new closed-form expressions for both exact and asymptotic outage probability as well as delay-limited throughput are derived for each NOMA user. Based on the analytical results derived, the diversity orders achieved by users are obtained. It is confirmed that the use of the direct link overcomes the zero diversity order of far NOMA user inherent to FD relaying. Simulation results demonstrate that the outage performance of FD NOMA is superior to HD NOMA at low SNR region rather than at high SNR region.","Title: Performance Analysis of Non-Regenerative Massive-MIMO-NOMA Relay Systems for 5G.\nYear: 2017\n\nAbstract: The non-regenerative massive multi-input-multioutput (MIMO) non-orthogonal multiple access (NOMA) relay systems are introduced in this paper. The NOMA is invoked with a superposition coding technique at the transmitter and successive interference cancellation (SIC) technique at the receiver. In addition, a maximum mean square error-SIC receiver design is adopted. With the aid of deterministic equi...","Title: Multiple-Antenna-Assisted Non-Orthogonal Multiple Access.\nYear: 2018\n\nAbstract: Non-orthogonal multiple access (NOMA) is potentially capable of circumventing the limitations of the classic orthogonal multiple access schemes. Hence, it has recently received significant research attention in both industry and academia. This article is focused on exploiting multiple antenna techniques in NOMA networks, with an emphasis on investigating the rate region of MIMO-NOMA, while reviewi...","Title: Network Topology Optimization By Turning Non-Scale-Free Networks Into Scale-Free Networks Using Nonlinear Preferential Rewiring Method\nYear: 2018\n\nAbstract: In practical application, the generation and evolution of many real networks always do not follow rigorous mathematical model, making network topology optimization a great challenge in the field of complex networks. In this research, we optimize the topology of non-scale-free networks by turning it into scale-free networks using a nonlinear preferential rewiring method. For different kinds of original networks generated by Watts and Strogatz model, we systematically demonstrate the optimization process and the modified networks to verify the performance of nonlinear preferential rewiring. We conduct further researches to explore the effect of nonlinear preferential rewiring's parameters on performance. Simulation results show that various non-scale-free networks with different network topologies generated by WS model, including random networks and various networks between regular and random, are turned into scale-free networks perfectly by nonlinear preferential rewiring method.","Title: Energy-Efficient Hybrid Precoding for mmWave Massive MIMO Systems\nYear: 2018\n\nAbstract: In millimeter Wave (mmWave) massive multi-input multi-output (MIMO) systems, the novel sub-connected architecture has been introduced which can further reduce power consumption compared with the fully-connected architecture. In this paper, we propose an energy-efficient hybrid precoding design with quality of service (QoS) constraints for sub-connected architecture. Firstly, the total energy efficiency optimization problem with nonconvex constraints is decomposed into two separate optimization sub-problems whose solution is a optimal single precoder respectively. Then, the first optimization sub-problem analog domain concerned is solved by a cross-entropy-based algorithm according to the machine learning theory. Finally, the second optimization sub-problem digital domain concerned is solved by an iterative optimization algorithm from fractional programming theory. Simulation results demonstrate that the performance of the proposed precoding algorithm. The performance of the proposed algorithm is capable of achieving near optimal solution. It is also demonstrated that the proposed algorithm can enhance the energy efficiency of networks while guaranteeing the QoS of users.","Title: Spatio-temporal Correlated Channel Feedback for Massive MIMO Systems\nYear: 2018\n\nAbstract: Accurate channel state information (CSI) at base station (BS) is the key to achieve full multiplexing and diversity gain in traditional multiple-input multiple-output (MIMO) systems. In frequency-division-duplex (FDD) systems, it is obtained through downlink training and uplink feedback. However, the training and feedback overhead in massive MIMO systems is unacceptable for the large number of antennas equipped at BS. To reduce the CSI feedback overhead and improve CSI quantization accuracy, we propose a limited feedback scheme for spatio-temporal correlated massive MIMO channel. The proposed scheme jointly performs Karhunen-Loève transform (KLT) and polar-cap quantization on CSI. For the compactly deployed antennas at BS, there exists spatial correlation in massive MIMO channel. When the user equipment (UE) moves slowly, adjacent channels feature temporal correlation. The high dimensional and spatial correlated CSI is compressed through KLT. Then the compressed CSI is normalized to be isotropic to perform polar-cap quantization. Simulation results show that the proposed scheme is capable of improving the sum-rate performance with limited feedback bits for massive MIMO systems.","Title: Exploiting NOMA/OMA for Multi-UAV Communications in Large-Scale Networks.\nYear: 2019\n\nAbstract: This paper advocates a pair of strategies in non-orthogonal multiple access (NOMA) in unmanned aerial vehicles (UAVs) communications, where multiple UAVs play as new aerial communications platforms for serving terrestrial NOMA users. A new multiple UAVs framework with invoking stochastic geometry technique is proposed, in which a pair of practical strategies are considered: 1) UAV-Centric strategy for offloading actions and 2) User-Centric strategy for providing emergency communications. In order to provide practical insights for the proposed NOMA assisted UAV framework, an imperfect successive interference cancelation (ipSIC) scenario is taken into account. For both UAV-Centric strategy and User-Centric strategy, we derive new exact expressions for the coverage probability. We also derive new analytical results for orthogonal multiple access (OMA) for providing a benchmark scheme. The derived analytical results in both User-Centric strategy and UAV-Centric strategy explicitly indicate that the ipSIC coefficient is a dominant component in terms of coverage probability. Numerical results are provided to confirm that i) for both User-Centric strategy and UAV-Centric strategy, NOMA assisted multi-UAV networks is capable of outperforming OMA by setting power allocation factors and targeted rate properly; and ii) the coverage probability of NOMA assisted multi-UAV framework is affected to a large extent by ipSIC coefficient, target rates and power allocations factors of paired NOMA users.","Title: Trajectory Design and Power Control for Multi-UAV Assisted Wireless Networks: A Machine Learning Approach.\nYear: 2019\n\nAbstract: A novel framework is proposed for the trajectory design of multiple unmanned aerial vehicles (UAVs) based on the prediction of usersu0027 mobility information. The problem of joint trajectory design and power control is formulated for maximizing the instantaneous sum transmit rate while satisfying the rate requirement of users. In an effort to solve this pertinent problem, a three-step approach is proposed which is based on machine learning techniques to obtain both the position information of users and the trajectory design of UAVs. Firstly, a multi-agent Q-learning based placement algorithm is proposed for determining the optimal positions of the UAVs based on the initial location of the users. Secondly, in an effort to determine the mobility information of users based on a real dataset, their position data is collected from Twitter to describe the anonymous user-trajectories in the physical world. In the meantime, an echo state network (ESN) based prediction algorithm is proposed for predicting the future positions of users based on the real dataset. Thirdly, a multi-agent Q-learning based algorithm is conceived for predicting the position of UAVs in each time slot based on the movement of users. The algorithm is proved to be able to converge to an optimal state. In this algorithm, multiple UAVs act as agents to find optimal actions by interacting with their environment and learn from their mistakes. Numerical results are provided to demonstrate that as the size of the reservoir increases, the proposed ESN approach improves the prediction accuracy. Finally, we demonstrate that throughput gains of about $17%$ are achieved.","Title: Performance Analysis of FD-NOMA-based Decentralized V2X Systems\nYear: 2019\n\nAbstract: In order to meet the requirements of massively connected devices, different quality of services (QoS), various transmit rates, and ultra-reliable and low latency communications (URLLC) in vehicle-to-everything (V2X) communications, we introduce a full duplex non-orthogonal multiple access (FD-NOMA)-based decentralized V2X system model. We, then, classify the V2X communications into two scenarios and give their exact capacity expressions. To solve the computation complicated problems of the involved exponential integral functions, we give the approximate closed-form expressions with arbitrary small errors. Numerical results indicate the validness of our derivations. Our analysis has that the accuracy of our approximate expressions is controlled by the division of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\frac {\\pi }{2}$ </tex-math></inline-formula>\n in the urban and crowded scenarios, and the truncation point \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">${T}$ </tex-math></inline-formula>\n in the suburban and remote scenarios. Numerical results manifest that: 1) increasing the number of V2X device, NOMA power, and Rician factor value yields a better capacity performance; 2) effect of FD-NOMA is determined by the FD self-interference and the channel noise; and 3) FD-NOMA has a better latency performance compared with other schemes.","Title: Reinforcement Learning in Multiple-UAV Networks: Deployment and Movement Design.\nYear: 2019\n\nAbstract: A novel framework is proposed for quality of experience (QoE)-driven deployment and dynamic movement of multiple unmanned aerial vehicles (UAVs). The problem of joint non-convex three-dimensional (3D) deployment and dynamic movement of the UAVs is formulated for maximizing the sum mean opinion score (MOS) of ground users, which is proved to be NP-hard. In the aim of solving this pertinent problem, a three-step approach is proposed for attaining 3D deployment and dynamic movement of multiple UAVs. Firstly, genetic algorithm based K-means (GAK-means) algorithm is utilized for obtaining the cell partition of the users. Secondly, Q-learning based deployment algorithm is proposed, in which each UAV acts as an agent, making their own decision for attaining 3D position by learning from trial and mistake. In contrast to conventional genetic algorithm based learning algorithms, the proposed algorithm is capable of training the direction selection strategy offline. Thirdly, Q-learning based movement algorithm is proposed in the scenario that the users are roaming. The proposed algorithm is capable of converging to an optimal state. Numerical results reveal that the proposed algorithms show a fast convergence rate after a small number of iterations. Additionally, the proposed Q-learning based deployment algorithm outperforms K-means algorithms and Iterative-GAKmean (IGK) algorithms with a low complexity.","Title: Performance Analysis of Clustered LoRa Networks.\nYear: 2019\n\nAbstract: In this paper, we investigate the uplink transmission performance of low-power wide-area (LPWA) networks with regards to coexisting radio modules. We adopt the long-range (LoRa) radio technique as an example of the network of focus, even though our analysis can be easily extended to other situations. We exploit a new topology to model the network, where the node locations of LoRa follow a Poisson cluster process while other coexisting radio modules follow a Poisson point process. Unlike most of the performance analysis based on stochastic geometry, we take noise into consideration. More specifically, two models, with a fixed and a random number of active LoRa nodes in each cluster, respectively, are considered. To obtain insights, both the exact and simple approximated expressions for coverage probability are derived. Based on them, area spectral efficiency and energy efficiency are obtained. From our analysis, we show how the performance of LPWA networks can be enhanced by adjusting the density of LoRa nodes around each LoRa receiver. Moreover, the simulation results unveil that the optimal number of active LoRa nodes in each cluster exists to maximize the area spectral efficiency.","Title: Introduction to the Issue on Signal Processing Advances for Non-Orthogonal Multiple Access in Next Generation Wireless Networks.\nYear: 2019\n\nAbstract: The papers in this special section focus on signal processing advances in non-orthogonal multiple access (NOMA) and network generation wireless networks. Recent years have witnessed the explosive growth ofmobile data traffic, which has led to ever-increasing demand for high system throughput, massive user access, heterogeneous data traffic, high bandwidth efficiency, and ultra-low latency. Non-ort...","Title: Clustered Millimeter-Wave Networks With Non-Orthogonal Multiple Access\nYear: 2019\n\nAbstract: We introduce clustered millimeter-wave (mmWave) networks with invoking non-orthogonal multiple access (NOMA) techniques, where the NOMA users are modeled as Poisson cluster processes and each cluster contains a base station (BS) located at the center. To provide realistic directional beamforming, an actual antenna array pattern is deployed at all BSs. We propose three distance-dependent user selection strategies to appraise the path loss impact on the performance of our considered networks. With the aid of such strategies, we derive tractable analytical expressions for the coverage probability and system throughput. Specifically, closed-form expressions are deduced under a sparse network assumption to improve the calculation efficiency. It theoretically demonstrates that the large antenna scale benefits the near user, while such influence for the far user is fluctuant due to the randomness of the beamforming. Moreover, the numerical results illustrate that: 1) the proposed system outperforms traditional orthogonal multiple access techniques and the commonly considered NOMA-mmWave scenarios with the random beamforming; 2) the coverage probability has a negative correlation with the variance of intra-cluster receivers; 3) 73 GHz is the best carrier frequency for the near user, and 28 GHz is the best choice for the far user; and 4) an optimal number of the antenna elements exists for maximizing the system throughput.","Title: Joint Impact of Hardware Impairments and Imperfect Channel State Information on Multi-Relay Networks\nYear: 2019\n\nAbstract: In this paper, we investigate the performance of dual-hop (DH) decode-and-forward (DF) multi-relay networks, for which two practical deleterious factors are taken into account, namely hardware impairments (HIs) and imperfect channel state information (ICSI). The communication between the source and the destination is realized with the aid of DF multi-relays, where both hops are assumed to be independent but non-identically distributed alpha-mu fading. Aiming at improving the system performance, three representative relay selection strategies are considered, in which the best relay is selected according to the link quality of source-to-relay and/or relay-to-destination. To characterize the performance of the proposed strategies, two key performance metrics, namely outage probability (OP) and ergodic capacity (EC), are analyzed insightfully. We first derive closed-form expressions for both exact and asymptotic OPs. Utilizing the derived results, diversity orders achieved at the destinations are obtained. We demonstrate that the OPs of considered networks are limited by HIs and ICSI, and the diversity orders are zeros due to the presence of ICSI. Then, we study the ECs of the proposed relay selection schemes, and upper bounds for the EC and asymptotic expressions for the EC in the high signal-to-noise ratio (SNR) regime are derived. To obtain more insights, the affine expansions for the EC are involved by two metrics of high-SNR slope and high-SNR power offset. It is shown that there are rate ceilings for the EC due to HIs and ICSI, which result in zero high-SNR slopes and finite high-SNR power offsets.","Title: Uplink Non-Orthogonal Multiple Access for UAV Communications.\nYear: 2019\n\nAbstract: This paper investigates ground-aerial uplink non-orthogonal multiple access (NOMA) cellular networks. A rotary-wing unmanned aerial vehicle (UAV) user and multiple ground users (GUEs) are served by ground base stations (GBSs) by utilizing uplink NOMA protocol. The UAV is dispatched to upload specific information bits to each target GBSs. Specifically, our goal is to minimize the UAV mission completion time by jointly optimizing the UAV trajectory and UAV-GBS association order while taking into account the UAV's interference to non-associated GBSs. The formulated problem is a mixed integer non-convex problem and involves infinite variables. To tackle this problem, we efficiently check the feasibility of the formulated problem by utilizing graph theory and topology theory. Next, we prove that the optimal UAV trajectory need to satisfy the \\emph{fly-hover-fly} structure. With this insight, we first design an efficient solution with predefined hovering locations by leveraging graph theory techniques. Furthermore, we propose an iterative UAV trajectory design by applying successive convex approximation (SCA) technique, which is guaranteed to coverage to a locally optimal solution. We demonstrate that the two proposed designs exhibit polynomial time complexity. Finally, numerical results show that: 1) the SCA based design outperforms the fly-hover-fly based design; 2) the UAV mission completion time is significantly minimized with proposed NOMA schemes compared with the orthogonal multiple access (OMA) scheme; 3) the increase of GUEs' QoS requirements will increase the UAV mission completion time.","Title: The Application Of Multi-Agent Reinforcement Learning In Uav Networks\nYear: 2019\n\nAbstract: This article investigates autonomous resource allocation of multiple UAVs enabled communication networks with the goal of maximizing long-term rewards. To model the uncertainty of environments, we formulate the long-term resource allocation problem as a stochastic game, where each UAV becomes a learning agent and each resource allocation solution corresponds to an action taken by the UAVs. Furthermore, we propose a multi-agent reinforcement learning (MARL) framework that. each agent discovers its best strategy according to its local observations using learning. More specifically, we propose an agent-independent method, for which all agents conduct a decision algorithm independently but share a common structure based on Q-learning. Finally, simulation results reveal that the proposed MARL algorithm provides acceptable performance compared to the case with complete information exchanges among UAVs.","Title: Modeling and Coverage Analysis of Downlink UAV Networks with MmWave Communications\nYear: 2019\n\nAbstract: In order to satisfy the requirement of high throughput in most unmanned aerial vehicle (UAV) applications, the potential of integrating millimeter wave (mmWave) communications into UAV networks is explored in this paper. A tractable three-dimensional (3D) spatial model is proposed for evaluating the average downlink performance of UAV networks at mmWave bands, where the locations of UAVs and users are randomly distributed with the aid of a Poisson cluster process. Moreover, a typical 3D antenna model with the uniform planar array is deployed at all UAVs to examine the impact of both azimuth and elevation angles. Based on this framework and an ordered user selection scheme, closed-form approximation equations of coverage probabilities are derived. In a noise-limited scenario, an exact expression is provided, which theoretically demonstrates that the coverage performance can be enhanced by increasing the number of antenna elements. Regarding the altitude of UAVs, there exists an optimal height for maximizing the evaluated coverage probability. Numerical results illustrate that non-line-of-sight transmissions caused by obstacles have negligible effects on the considered system.","Title: Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G\nYear: 2022\n\nAbstract: Due to the explosive growth in the number of wireless devices and diverse wireless services, such as virtual/augmented reality and Internet-of-Everything, next generation wireless networks face unprecedented challenges caused by heterogeneous data traffic, massive connectivity, and ultra-high bandwidth efficiency and ultra-low latency requirements. To address these challenges, advanced multiple access schemes are expected to be developed, namely next generation multiple access (NGMA), which are capable of supporting massive numbers of users in a more resource- and complexity-efficient manner than existing multiple access schemes. As the research on NGMA is in a very early stage, in this paper, we explore the evolution of NGMA with a particular focus on non-orthogonal multiple access (NOMA), i.e., the transition from NOMA to NGMA. In particular, we first review the fundamental capacity limits of NOMA, elaborate on the new requirements for NGMA, and discuss several possible candidate techniques. Moreover, given the high compatibility and flexibility of NOMA, we provide an overview of current research efforts on multi-antenna techniques for NOMA, promising future application scenarios of NOMA, and the interplay between NOMA and other emerging physical layer techniques. Furthermore, we discuss advanced mathematical tools for facilitating the design of NOMA communication systems, including conventional optimization approaches and new machine learning techniques. Next, we propose a unified framework for NGMA based on multiple antennas and NOMA, where both downlink and uplink transmissions are considered, thus setting the foundation for this emerging research area. Finally, several practical implementation challenges for NGMA are highlighted as motivation for future work.","Title: Transmit Power Pool Design for Uplink IoT Networks with Grant-free NOMA\nYear: 2021\n\nAbstract: Grant-free non-orthogonal multiple access (GFNOMA) is a potential multiple access framework for internet-of-things (IoT) networks to enhance connectivity. However, the resource allocation problem in GF-NOMA is challenging and the effectiveness of such a solution is limited due to the absence of closed-loop power control. In this paper, we design a prototype of layer-based transmit power pool by utilizing multi-agent reinforcement learning to provide open-loop power control and offload the computing tasks at the base station (BS) side. IoT users in each layer decide their own transmit power level from this layer-based power pool, instead of transmitting on the allocated sub-channel with allocated transmit power level. The proposed algorithm does not require any information exchange between IoT users and does not rely on any assistance from the BS. Numerical results confirm that the double deep Q network based GF-NOMA algorithm achieves high accuracy and finds out an accurate transmit power level for each layer. Moreover, the proposed GF-NOMA system outperforms the traditional GF with orthogonal multiple access techniques in terms of throughput.","Title: Capacity Characterization of Intelligent Reflecting Surface Assisted NOMA Systems\nYear: 2021\n\nAbstract: This paper investigates intelligent reflecting surface (IRS)-assisted systems, where an access point sends independent information to multiple users with the aid of one IRS. Our goal is to characterize the capacity region of the IRS-assisted multiuser communication systems. We jointly optimize the discrete phase-shift matrix of the IRS and resource allocation with the capacity-achieving non-orthogonal multiple access (NOMA) transmission scheme. The Pareto boundary of the capacity region is characterized by maximizing the average sum rate of all users, subject to a set of rate-profile constraints, total transmit power and discrete IRS phase shift constraints. Though the formulated problem is non-convex, we derive the globally optimal solutions by invoking the Lagrange duality method. It is shown that the optimal transmission strategy is alternating transmission among different user groups by dynamically adjusting the IRS phase shifts. We further propose a Hadamard codebook based scheme, which serves as a lower bound on the optimal performance gains. Numerical results demonstrate that: i) the IRS is capable of significantly improving the capacity region; ii) the capacity region achieved by the Hadamard codebook based scheme is close to that of discrete phase shifts for a small number of IRS elements.","Title: STAR-RIS Aided NOMA in Multicell Networks: A General Analytical Framework With Gamma Distributed Channel Modeling\nYear: 2022\n\nAbstract: The simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is capable of providing full-space coverage of smart radio environments. This work investigates STAR-RIS aided downlink non-orthogonal multiple access (NOMA) multi-cell networks, where the energy of incident signals at STAR-RISs is split into two portions for transmitting and reflecting. We first propose a fitting method to model the distribution of composite small-scale fading power as the tractable Gamma distribution. Then, a unified analytical framework based on stochastic geometry is provided to capture the random locations of RIS-RISs, base stations (BSs), and user equipments (UEs). Based on this framework, we derive the coverage probability and ergodic rate of both the typical UE and the connected UE. In particular, we obtain closed-form expressions of the coverage probability in interference-limited scenarios. We also deduce theoretical expressions in conventional RIS aided networks for comparison. The analytical results show that optimal energy splitting coefficients of STAR-RISs exist to simultaneously maximize the system coverage and ergodic rate. The numerical results demonstrate that: 1) STAR-RISs are able to meet different demands of UEs located on different sides; 2) STAR-RISs with appropriate energy splitting coefficients outperform conventional RISs in the coverage and the rate performance.","Title: Trajectory Optimization for UAV Emergency Communication With Limited User Equipment Energy: A Safe-DQN Approach\nYear: 2021\n\nAbstract: In post-disaster scenarios, it is challenging to provide reliable and flexible emergency communications, especially when the mobile infrastructure is seriously damaged. This article investigates the unmanned aerial vehicle (UAV)-based emergency communication networks, in which UAV is used as a mobile aerial base station for collecting information from ground users in affected areas. Due to the bre...","Title: STAR-RIS Integrated Nonorthogonal Multiple Access and Over-the-Air Federated Learning: Framework, Analysis, and Optimization\nYear: 2022\n\nAbstract: This article integrates nonorthogonal multiple access (NOMA) and over-the-air federated learning (AirFL) into a unified framework using one simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS). The STAR-RIS plays an important role in adjusting the decoding order of hybrid users for efficient interference mitigation and omnidirectional coverage extension. To capture the impact of nonideal wireless channels on AirFL, a closed-form expression for the optimality gap (also known as the convergence upper bound) between the actual loss and the optimal loss is derived. This analysis reveals that the learning performance is significantly affected by the active and passive beamforming schemes, as well as wireless noise. Furthermore, when the learning rate diminishes as the training proceeds, the optimality gap is explicitly shown to converge with a linear rate. To accelerate convergence while satisfying quality-of-service requirements, a mixed-integer nonlinear programming (MINLP) problem is formulated by jointly designing the transmit power at users and the configuration mode of STAR-RIS. Next, a trust-region-based successive convex approximation method and a penalty-based semidefinite relaxation approach are proposed to handle the decoupled nonconvex subproblems iteratively. An alternating optimization algorithm is then developed to find a suboptimal solution for the original MINLP problem. Extensive simulation results show that: 1) the proposed framework can efficiently support NOMA and AirFL users via concurrent uplink communications; 2) our algorithms achieve a faster convergence rate on independent and identically distributed (IID) and non-IID settings compared to the existing baselines; and 3) both the spectrum efficiency and learning performance are significantly improved with the aid of the well-tuned STAR-RIS.","Title: STAR-RISs: Simultaneous Transmitting and Reflecting Reconfigurable Intelligent Surfaces\nYear: 2021\n\nAbstract: In this letter, simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) are studied. Compared with the conventional reflecting-only RISs, the coverage of STAR-RISs is extended to 360 degrees via simultaneous transmission and reflection. A general hardware model for STAR-RISs is presented. Then, channel models are proposed for the near-field and the far-field scenar...","Title: STAR-IOS Aided NOMA Networks: Channel Model Approximation and Performance Analysis\nYear: 2022\n\nAbstract: Compared with the conventional reconfigurable intelligent surfaces (RIS), simultaneous transmitting and reflecting intelligent omini-surfaces (STAR-IOSs) are able to achieve 360° coverage “smart radio environments”. By splitting the energy or altering the active number of STAR-IOS elements, STAR-IOSs provide high flexibility of successive interference cancellation (SIC) orders for non-orthogonal multiple access (NOMA) systems. Based on the aforementioned advantages, this paper investigates a STAR-IOS-aided downlink NOMA network with randomly deployed users. We first propose three tractable channel models for different application scenarios, namely the central limit model, the curve fitting model, and the M-fold convolution model. More specifically, the central limit model fits the scenarios with large-size STAR-IOSs while the curve fitting model is extended to evaluate multi-cell networks. However, these two models cannot obtain accurate diversity orders. Hence, we figure out the M-fold convolution model to derive accurate diversity orders. We consider three protocols for STAR-IOSs, namely, the energy splitting (ES) protocol, the time switching (TS) protocol, and the mode switching (MS) protocol. Based on the ES protocol, we derive closed-form analytical expressions of outage probabilities for the paired NOMA users by the central limit model and the curve fitting model. Based on three STAR-IOS protocols, we derive the diversity gains of NOMA users by the M-fold convolution model. The analytical results reveal that the diversity gain of NOMA users is equal to the active number of STAR-IOS elements. Numerical results indicate that 1) in high signal-to-noise ratio regions, the central limit model performs as an upper bound of the simulation results, while a lower bound is obtained by the curve fitting model; 2) the TS protocol has the best performance but requesting more time blocks than other protocols; 3) the ES protocol outperforms the MS protocol as the ES protocol has higher diversity gains.","Title: Graph-Embedded Multi-Agent Learning for Smart Reconfigurable THz MIMO-NOMA Networks\nYear: 2022\n\nAbstract: With the accelerated development of immersive applications and the explosive increment of internet-of-things (IoT) terminals, 6G would introduce terahertz (THz) massive multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) technologies to meet the ultra-high-speed data rate and massive connectivity requirements. Nevertheless, the unreliability of THz transmissions and the extre...","Title: Energy-Constrained UAV Data Collection Systems: NOMA and OMA\nYear: 2021\n\nAbstract: This paper investigates unmanned aerial vehicle (UAV) data collection systems with different multiple access schemes, where a rotary-wing UAV is dispatched to collect data from multiple ground nodes (GNs). Our goal is to maximize the minimum UAV data collection throughput from GNs for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) transmission, subject to the energ...","Title: Over-the-Air Federated Learning and Non-Orthogonal Multiple Access Unified by Reconfigurable Intelligent Surface\nYear: 2021\n\nAbstract: With the aim of integrating over-the-air federated learning (AirFL) and non-orthogonal multiple access (NOMA) into an on-demand universal framework, this paper proposes a novel reconfigurable intelligent surface (RIS)-unified network by leveraging the RIS to flexibly adjust the signal processing order of hybrid users. The objective of this work is to maximize the achievable hybrid rate of all users by jointly optimizing the transmit power at users, controlling the receive scalar at the base station, and designing the phase shifts at the RIS. Due to the fact that all signals of computation and communication are combined into one concurrent transmission, the formulated resource allocation problem is very challenging. To solve this problem, the alternating optimization is invoked to address non-convex subproblems iteratively for finding a suboptimal solution with low complexity. Simulation results demonstrate that i) the proposed RIS-unified network can support the on-demand communication and computation efficiently, and ii) the designed algorithms are also applicable to conventional networks with only AirFL or NOMA users.","Title: Adaptive Reinforcement Learning Framework for NOMA-UAV Networks\nYear: 2021\n\nAbstract: We propose an adaptive reinforcement learning (A-RL) framework to maximize the sum-rate for non-orthogonal multiple access-unmanned aerial vehicle (NOMA-UAV) network. In this framework, Mamdani fuzzy inference system (MFIS) supervises a reinforcement learning (RL) policy based on multi-armed bandits (MAB). UAV as learning agent serves an internet of things (IoT) region. It manages an interference ...","Title: Simultaneously Transmitting and Reflecting (STAR)-RISs: A Coupled Phase-Shift Model\nYear: 2022\n\nAbstract: A simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided communication system is investigated, where an access point sends information to two users located on each side of the STAR-RIS. Different from current works assuming that the phase-shift coefficients for transmission and reflection can be independently adjusted, which is non-trivial to realize for purely passive STAR-RISs, a coupled transmission and reflection phase-shift model is considered. Based on this model, a power consumption minimization problem is formulated for both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA). In particular, the amplitude and phase-shift coefficients for transmission and reflection are jointly optimized, subject to the rate constraints of the users. To solve this non-convex problem, an efficient element-wise alternating optimization algorithm is developed to find a high-quality suboptimal solution, whose complexity scales only linearly with the number of STAR elements. Finally, numerical results are provided for both NOMA and OMA to validate the effectiveness of the proposed algorithm by comparing its performance with that of STAR-RISs using the independent phase-shift model and conventional reflecting/transmitting-only RISs.","Title: NOMA-Aided Joint Radar and Multicast-Unicast Communication Systems\nYear: 2022\n\nAbstract: The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric users (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">double spectrum sharing</i>\n, where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. First, a \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">beamformer-based</i>\n NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Next, the system is extended to the scenario of multiple pairs of R- and C-users, where a \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">cluster-based</i>\n NOMA-aided joint Rad-MU-Com framework is proposed. A joint beamformer design and power allocation optimization problem is formulated for the maximization of the sum of the unicast rate at each C-user, subject to the constraints on both the minimum multicast rate for each R&C pair and on accuracy of the radar beam pattern for detecting multiple R-users. The resultant joint optimization problem is efficiently solved by another penalty-based iterative algorithm developed. Finally, our numerical results reveal that significant performance gains can be achieved by the proposed schemes over the benchmark schemes employing conventional transmission strategies.","Title: Meta-learning for RIS-assisted NOMA Networks\nYear: 2021\n\nAbstract: A novel reconfigurable intelligent surfaces (RISs)-based transmission framework is proposed for downlink non-orthogonal multiple access (NOMA) networks. We propose a quality-of-service (QoS)-based clustering scheme to improve the resource efficiency and formulate a sum rate maximization problem by jointly optimizing the phase shift of the RIS and the power allocation at the base station (BS). A model-agnostic meta-learning (MAML)-based learning algorithm is proposed to solve the joint optimization problem with a fast convergence rate and low model complexity. Extensive simulation results demonstrate that the proposed QoS-based NOMA network achieves significantly higher transmission throughput compared to the conventional orthogonal multiple access (OMA) network. It can also be observed that substantial throughput gain can be achieved by integrating RISs in NOMA and OMA networks. Moreover, simulation results of the proposed QoS-based clustering method demonstrate observable throughput gain against the conventional channel condition-based schemes.","Title: Resource Allocation in STAR-RIS-Aided Networks: OMA and NOMA\nYear: 2022\n\nAbstract: Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is a promising technology that aids in achieving full-space coverage on both sides of the surface, by splitting the incident signal into transmitted and reflected signals. This paper investigates the resource allocation problem in a STAR-RIS-assisted multi-carrier communication networks. To maximize the system sum-rate, a joint optimization problem comprising of the channel assignment, power allocation, and transmission and reflection beamforming at the STAR-RIS for orthogonal multiple access (OMA) is first formulated. To solve this challenging problem, we first propose a channel assignment scheme utilizing matching theory and then invoke the alternating optimization-based method to optimize the resource allocation policy and beamforming vectors iteratively. Furthermore, the sum-rate maximization problem for non-orthogonal multiple access (NOMA) with flexible decoding orders is investigated. To efficiently solve it, we first propose a location-based matching algorithm to determine the sub-channel assignment, where a transmitted user and a reflected user are grouped on a sub-channel. Based on this \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">transmission-and-reflection</i>\n sub-channel assignment strategy, a three-step approach is proposed, which involves the optimization of decoding orders, beamforming-coefficient vectors, and power allocation, by employing semidefinite programming, convex upper bound approximation, and geometry programming, respectively. Numerical results unveil that: 1) For OMA, a general design that includes the same-side user-pairing for channel assignment is preferable, whereas for NOMA, the proposed transmission-and-reflection scheme can achieve comparable performance to the exhaustive search-based algorithm. 2) The STAR-RIS-aided NOMA network significantly outperforms networks employing conventional RISs and OMA.","Title: A Novel Design of RIS for Enhancing the Physical Layer Security for RIS-Aided NOMA Networks\nYear: 2021\n\nAbstract: This letter proposes a novel design of reconfigurable intelligent surface (RIS) to enhance the physical layer security (PLS) in the RIS-aided non-orthogonal multiple access (NOMA) network. Under the design of the RIS, the problem of increasing the number of RIS elements damaging the secrecy performance is solved. Besides, it also ensures that the networks can use traditional channel coding schemes...","Title: AI-Driven UAV-NOMA-MEC in Next Generation Wireless Networks\nYear: 2021\n\nAbstract: Driven by the unprecedented high throughput and low latency requirements anticipated for next generation wireless networks, this article introduces an artificial intelligence (AI)-enabled framework in which unmanned aerial vehicles use non-orthogonal multiple access and mobile edge computing techniques to serve terrestrial mobile users (MUs). The proposed framework enables terrestrial MUs to offlo...","Title: User Grouping and Energy Harvesting in UAV-NOMA System With AF/DF Relaying\nYear: 2021\n\nAbstract: The development of unmanned aerial vehicles (UAVs) is one of the driving forces for revolutionizing wireless communications in the modern era. Although there are many unique features of UAV networks, their widespread use is still hampered by the short battery life. As a result, most of the research efforts in this domain mainly have focused on the efficient use of energy through trajectory plannin...","Title: STAR-RISs: A Correlated T&R Phase-Shift Model and Practical Phase-Shift Configuration Strategies\nYear: 2022\n\nAbstract: A \n<italic xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">correlated</i>\n transmission and reflection (T&R) phase-shift model is proposed for passive lossless simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs). A STAR-RIS-aided two-user downlink communication system is investigated for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA). To evaluate the impact of the correlated T&R phase-shift model on the communication performance, three phase-shift configuration strategies are developed, namely the primary-secondary phase-shift configuration (PS-PSC), the diversity preserving phase-shift configuration (DP-PSC), and the T/R-group phase-shift configuration (TR-PSC) strategies. Furthermore, we derive the outage probabilities for the three proposed phase-shift configuration strategies as well as for those for the random phase-shift configuration and the independent phase-shift model, which constitute performance lower and upper bounds, respectively. Then, the diversity order of each strategy is investigated based on the obtained analytical results. It is shown that the proposed DP-PSC strategy achieves full diversity order simultaneously for users located on both sides of the STAR-RIS. Moreover, power scaling laws are derived for the three proposed strategies and for the random phase-shift configuration. Numerical simulations reveal a performance gain if the users on both sides of the STAR-RIS are served by NOMA instead of OMA. Moreover, it is shown that the proposed DP-PSC strategy yields the same diversity order as achieved by STAR-RISs under the independent phase-shift model and a comparable power scaling law with only 4 dB reduction in received power.","Title: A New Look at AI-Driven NOMA-F-RANs: Features Extraction, Cooperative Caching, and Cache-Aided Computing\nYear: 2022\n\nAbstract: Non-orthogonal multiple access-enabled fog radio access networks (NOMA-F-RANs) are thought of as a promising enabler to release network congestion, reduce delivery latency, and improve fog user equipment (F-UEs) quality of service. Never-theless, the effectiveness of NOMA-F-RANs highly relies on the charted feature information (e.g., preference distribution, positions, and mobilities) of F-UEs as well as the effective caching, computing, and resource allocation strategies. In this article, we explore how artificial intelligence (AI) techniques are utilized to solve foregoing challenges. Specifically, we first elaborate on the NOMA-F-RANs architecture, shedding light on the key modules, namely, cooperative caching and cache-aided mobile edge computing. Then, the potentially applicable AI-driven techniques in solving the principal issues of NOMA-F-RANs are reviewed. Through case studies, we show the efficacy of AI-enabled methods in terms of the latent feature extraction and cooperative caching of F-UEs. Finally, future trends of AI-driven NOMA-F-RANs, including open research issues and challenges, are identified.","Title: Channel Estimation for STAR-RIS-Aided Wireless Communication\nYear: 2022\n\nAbstract: In this letter, we study efficient uplink channel estimation design for a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted two-user communication systems. We first consider the time switching (TS) protocol for STAR-RIS and propose an efficient scheme to separately estimate the channels of the two users with optimized training (transmission/reflectio...","Title: NOMA Empowered Integrated Sensing and Communication\nYear: 2022\n\nAbstract: A non-orthogonal multiple access (NOMA) empowered integrated sensing and communication (ISAC) framework is investigated. A dual-functional base station serves multiple communication users employing NOMA, while the superimposed NOMA communication signal is simultaneously exploited for target sensing. A beamforming design problem is formulated to maximize the weighted sum of the communication throug...","Title: AI Empowered RIS-Assisted NOMA Networks: Deep Learning or Reinforcement Learning?\nYear: 2022\n\nAbstract: A reconfigurable intelligent surface (RIS)-assisted multi-user downlink communication system over fading channels is investigated, where both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) schemes are employed. In particular, the time overhead for configuring the RIS reflective elements at the beginning of each fading channel is considered. The optimization goal is maxi...","Title: NOMA Inspired Interference Cancellation for Integrated Sensing and Communication\nYear: 2022\n\nAbstract: A non-orthogonal multiple access (NOMA) inspired integrated sensing and communication (ISAC) system is investigated. A dual-functional base station (BS) serves multiple communication users while sensing multiple targets, by transmitting the non-orthogonal superposition of the communication and sensing signals. A NOMA inspired interference cancellation scheme is proposed, where part of the dedicated sensing signal is treated as the virtual communication signals to be mitigated at each communication user via successive interference cancellation (SIC). Based on this framework, the transmitted communication and sensing signals are jointly optimized to match the desired sensing beampattern, while satisfying the minimum rate requirement and the SIC condition at the communication users. Then, the formulated non-convex optimization problem is solved by invoking the successive convex approximation (SCA) to obtain a near-optimal solution. The numerical results show the proposed NOMA-inspired ISAC system can achieve better performance than the conventional ISAC system and comparable performance to the ideal ISAC system where all sensing interference is assumed to be removed unconditionally.","Title: On the Performance of Uplink ISAC Systems\nYear: 2022\n\nAbstract: This letter analyzes the performance of uplink integrated sensing and communications (ISAC) systems where communication users (CUs) and radar targets (RTs) share the same frequency band. A non-orthogonal multiple access (NOMA) protocol is adopted in the communication procedure of the ISAC system. Novel expressions are derived to characterize the outage probability, ergodic communication rate, and sensing rate. Besides, the diversity order and high signal-to-noise ratio (SNR) slope are unveiled to gain further insights. It is found that when achieving the same communication rate, the ISAC system enjoys a higher sensing rate than the conventional frequency-division sensing and communications (FDSAC) system where CUs and RTs share isolated bands. All the results are validated by numerical simulations and are in excellent agreement.","Title: Deep Learning for Latent Events Forecasting in Content Caching Networks\nYear: 2022\n\nAbstract: A novel Twitter context aided content caching (TAC) framework is proposed for enhancing the caching efficiency by taking advantage of the legibility and massive volume of Twitter data. For the purpose of promoting the caching efficiency, three machine learning models are proposed to predict latent events and events popularity, utilizing collected Twitter data with geo-tags and geographic informati...","Title: A Reliable Reinforcement Learning for Resource Allocation in Uplink NOMA-URLLC Networks\nYear: 2022\n\nAbstract: In this paper, we propose a deep state-action-reward-state-action (SARSA) \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\lambda $ </tex-math></inline-formula>\n learning approach for optimising the uplink resource allocation in non-orthogonal multiple access (NOMA) aided ultra-reliable low-latency communication (URLLC). To reduce the mean decoding error probability in time-varying network environments, this work designs a reliable learning algorithm for providing a long-term resource allocation, where the reward feedback is based on the instantaneous network performance. With the aid of the proposed algorithm, this paper addresses three main challenges of the reliable resource sharing in NOMA-URLLC networks: 1) user clustering; 2) Instantaneous feedback system; and 3) Optimal resource allocation. All of these designs interact with the considered communication environment. Lastly, we compare the performance of the proposed algorithm with conventional Q-learning and SARSA Q-learning algorithms. The simulation outcomes show that: 1) Compared with the traditional Q learning algorithms, the proposed solution is able to converge within 200 episodes for providing as low as \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$10^{-2}$ </tex-math></inline-formula>\n long-term mean error; 2) NOMA assisted URLLC outperforms traditional OMA systems in terms of decoding error probabilities; and 3) The proposed feedback system is efficient for the long-term learning process.","Title: MIMO Assisted Networks Relying on Intelligent Reflective Surfaces: A Stochastic Geometry Based Analysis\nYear: 2022\n\nAbstract: Intelligent reflective surfaces (IRSs) are invoked for improving both the spectral efficiency (SE) and energy efficiency (EE). Specifically, an IRS-aided multiple-input multiple-output network is considered, where the performance of randomly roaming users is analyzed by utilizing stochastic geometry tools. As such, to distinguish the superposed signals at each user, the passive beamforming weight ...","Title: Joint Trajectory and Resource Optimization for UAV-Aided Two-Way Relay Networks\nYear: 2022\n\nAbstract: Unmanned aerial vehicle (UAV)-aided two-way relay networks with multiple terrestrial user pairs is investigated, where a fix-wing UAV is served as a two-way relay to assist information transmission. We aim to maximize the total rate of the two-way relay networks while the quality of service (QoS) being guaranteed. A novel relay strategy, namely time-slots pairing, is proposed by e...","Title: STAR: Simultaneous Transmission and Reflection for 360° Coverage by Intelligent Surfaces\nYear: 2021\n\nAbstract: A novel simultaneous transmitting and reflecting (STAR) system design relying on reconfigurable intelligent surfaces (RISs) is conceived. First, an existing prototype is reviewed, and the potential benefits of STAR-RISs are discussed. Then the key differences between conventional reflecting-only RISs and STAR-RISs are identified from the perspectives of hardware design, physical principles, and co...","Title: Reliable Reinforcement Learning Based NOMA Schemes for URLLC\nYear: 2021\n\nAbstract: In this paper, we propose a deep state-action-reward-state-action (SARSA) \n<tex xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">$A$</tex>\n learning approach for optimising the uplink resource allocation in non-orthogonal multiple access (NOMA) aided ultra-reliable low-latency communication (URLLC). To reduce the mean decoding error probability in time-varying network environments, this work designs a reliable learning algorithm for providing a long-term resource allocation, where the reward feedback is based on the instantaneous network performance. With the aid of the proposed algorithm, this paper addresses three main challenges of the reliable resource sharing in NOMA-URLLC networks: 1) Dynamic user clustering; 2) Instantaneous feedback system; and 3) Optimal resource allocation. All of these designs interact with the considered communication environment. The simulation outcomes show that: 1) Compared with the traditional Q learning algorithm, the proposed solution converges faster and obtains better performance; 2) NOMA assisted URLLC outperforms traditional OMA systems in terms of decoding error probabilities; and 3) The dynamic feedback system is efficient for the long-term learning process.","Title: Enabling Ubiquitous Non-Orthogonal Multiple Access and Pervasive Federated Learning via STAR-RIS\nYear: 2021\n\nAbstract: This paper proposes a new, compatible, unified framework which integrates non-orthogonal multiple access (NOMA) and over-the-air federated learning (AirFL) via concurrent communication. In particular, a simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is leveraged to adjust the signal processing order for efficient interference mitigation and omni-directional coverage extension. With the aim of investigating the impact of non-ideal wireless communication on AirFL, we provide a closed-form expression for the optimality gap over a given number of communication rounds. This result reveals that the learning performance is significantly affected by the resource allocation scheme and channel noise. To minimize the derived optimality gap, a mixed-integer non-linear programming (MINLP) problem is formulated by jointly designing the transmit power at users and configuration mode at the STAR-RIS. Through developing an alternating optimization algorithm, a suboptimal solution for the original MINLP problem is obtained. Simulation results show that the learning performance in terms of training loss and test accuracy can be effectively improved with the aid of the STAR-RIS.","Title: Enhancing Security of NOMA Networks via Distributed Intelligent Reflecting Surfaces\nYear: 2021\n\nAbstract: This paper investigates the security enhancement of an intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) network, where a distributed IRS enabled NOMA transmission framework is proposed to serve users securely in the presence of a passive eavesdropper. Considering that the instantaneous channel state information (CSI) of the eavesdropper is challenging to acquire in practice, we utilize the secrecy outage probability (SOP) as the security metric. A problem by jointly optimizing the transmit power at the base station (BS) and reflection phase shifts at IRSs, subject to the successive interference cancellation (SIC) decoding constraints and SOP constraints, is formulated to maximize the minimum secrecy rate among legitimate users. To tackle the non-convex problem, we first derive the exact SOP in closed-form expressions and then propose a novel ring-penalty based successive convex approximation (SCA) algorithm to design power allocation and phase shifts jointly. Numerical results validate the convergence and the secrecy superiority of proposed scheme over the baseline schemes.","Title: Simultaneously Transmitting And Reflecting RIS Aided NOMA With Randomly Deployed Users\nYear: 2021\n\nAbstract: To achieve 360 degrees coverage, we investigate a simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) aided downlink non-orthogonal multiple access (NOMA) network with randomly deployed users. For different scenarios, we first derive two STAR-RIS-aided channel models, namely the central limit model and the curve fitting model. More specifically, the central limit model fits the scenarios with numerous RIS elements while the curve fitting model can be extended to multi-cell scenarios. The analytical results reveal that 1) the central limit model has closed-form expressions calculated as the error functions, and 2) the curve fitting model can be closely modeled as a Gamma distribution. We then derive the closed-form outage probability expressions for the NOMA users. Numerical results indicate that 1) the two channel models match the simulation results well in low signal-to-noise-ratio (SNR) regions and perform as boundaries in high SNR regions, 2) the central limit model performs as an upper bound of the simulation results, while a lower bound can be obtained by the curve fitting model, and 3) the both users in the NOMA pair have no error floor.","Title: Simultaneously Transmitting And Reflecting (STAR) RIS Assisted NOMA Systems\nYear: 2021\n\nAbstract: In this paper, a novel simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted non-orthogonal multiple access (NOMA) system is proposed, where the STAR-RIS can simultaneously transmit and reflect the incident signals. Our objective is to maximize the achievable sum rate by jointly optimizing the decoding order, power allocation coefficients, active beamforming, transmission and reflection beamformings. However, the formulated problem is non-convex with intricately coupled variables. To tackle this challenge, a suboptimal two-layer iterative algorithm is proposed. Specifically, in the inner-layer iteration, for a given decoding order, the power allocation coefficients, active beamforming, transmission and reflection beamformings are optimized alternatively. For the outer-layer iteration, the decoding order of NOMA users in each cluster is updated with the solutions obtained from the inner-layer iteration. Simulation results are provided to demonstrate that the proposed STAR-RSI-NOMA system outperforms conventional RIS assisted systems.","Title: Semi-Integrated-Sensing-and-Communication (Semi-ISaC) Networks Assisted by NOMA\nYear: 2022\n\nAbstract: This paper investigates non-orthogonal multiple access (NOMA) assisted integrated sensing and communication (ISaC) networks. Compared to the conventional ISaC networks, where the total bandwidth is used for both the radar detection and wireless communications, the proposed Semi-ISaC networks allow that a portion of bandwidth is used for ISaC and the rest of the bandwidth is only utilized for wireless communications. We first derive the analytical expressions of the outage probability for the communication signals, including the signals for the radar target and the communication transmitter. Additionally, we derive the analytical expressions of the ergodic radar estimation information rate (REIR) for the radar echoes. The simulation results show that 1) NOMA ISaC has better spectrum efficiency than the conventional ISaC; and 2) The REIR is enhanced when we enlarge the density of pulses.","Title: Energy Efficient Resource Allocation for MSCA Enabled CoMP in HetNets\nYear: 2022\n\nAbstract: A novel multi-stream carrier aggregation (MSCA) enabled coordinated multi-point (CoMP) framework in heterogeneous cellular networks (HetNets) is proposed. Our objective is to maximize the energy efficiency (EE) of the proposed framework by jointly optimizing base station (BS) clustering, user association, sub-carrier assignment and power allocation. The formulated problem is proved to be NP-hard. ...","Title: Joint Radar and Multicast-Unicast Communication: A NOMA Aided Framework\nYear: 2022\n\nAbstract: The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric user (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this double spectrum sharing, where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. A beamformer-based NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Finally, our numerical results reveal that significant performance gains can be achieved by the proposed scheme over the benchmark schemes.","Title: Learning Non-target Knowledge for Few-shot Semantic Segmentation\nYear: 2022\n\nAbstract: Existing studies in few-shot semantic segmentation only focus on mining the target object information, however, often are hard to tell ambiguous regions, especially in non-target regions, which include background (BG) and Distracting Objects (DOs). To alleviate this problem, we propose a novel framework, namely Non-Target Region Eliminating (NTRE) network, to explicitly mine and eliminate BG and DO regions in the query. First, a BG Mining Module (BGMM) is proposed to extract the BG region via learning a general BG prototype. To this end, we design a BG loss to supervise the learning of BGMM only using the known target object segmentation ground truth. Then, a BG Eliminating Module and a DO Eliminating Module are proposed to successively filter out the BG and DO information from the query feature, based on which we can obtain a BG and DO-free target object segmentation result. Furthermore, we propose a prototypical contrastive learning algorithm to improve the model ability of distinguishing the target object from DOs. Extensive experiments on both PASCAL-5 i and COCO-20 i datasets show that our approach is effective despite its simplicity. Code is available at https://github.com/LIUYUANWEI98/NERTNet","Title: Hybrid Reinforcement Learning for STAR-RISs: A Coupled Phase-Shift Model Based Beamformer\nYear: 2022\n\nAbstract: A simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted multi-user downlink multiple-input single-output (MISO) communication system is investigated. In contrast to the existing ideal STAR-RIS model assuming an independent transmission and reflection phase-shift control, a practical coupled phase-shift model is considered. Then, a joint active and passive beamforming optimization problem is formulated for minimizing the long-term transmission power consumption, subject to the coupled phase-shift constraint and the minimum data rate constraint. Despite the coupled nature of the phase-shift model, the formulated problem is solved by invoking a hybrid continuous and discrete phase-shift control policy. Inspired by this observation, a pair of hybrid reinforcement learning (RL) algorithms, namely the hybrid deep deterministic policy gradient (hybrid DDPG) algorithm and the joint DDPG & deep-Q network (DDPG-DQN) based algorithm are proposed. The hybrid DDPG algorithm controls the associated high-dimensional continuous and discrete actions by relying on the hybrid action mapping. By contrast, the joint DDPG-DQN algorithm constructs two Markov decision processes (MDPs) relying on an inner and an outer environment, thereby amalgamating the two agents to accomplish a joint hybrid control. Simulation results demonstrate that the STAR-RIS has superiority over other conventional RISs in terms of its energy consumption. Furthermore, both the proposed algorithms outperform the baseline DDPG algorithm, and the joint DDPG-DQN algorithm achieves a superior performance, albeit at an increased computational complexity.","Title: Special Issue on Next Generation Multiple Access—Part I\nYear: 2022\n\nAbstract: As the long-term evolution (LTE) system is reaching maturity and the fifth-generation (5G) systems are being commercially deployed, researchers have turned their attention to the development of next-generation wireless networks. Compared to current wireless networks, on the one hand, next-generation wireless networks are expected to achieve significantly higher capacity, extremely low latency, ult...","Title: Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G\nYear: 2022\n\nAbstract: Due to the explosive growth in the number of wireless devices and diverse wireless services, such as virtual/augmented reality and Internet-of-Everything, next generation wireless networks face unprecedented challenges caused by heterogeneous data traffic, massive connectivity, and ultra-high bandwidth efficiency and ultra-low latency requirements. To address these challenges, advanced multiple ac...","Title: Two Time-Scale Caching Placement and User Association in Dynamic Cellular Networks\nYear: 2022\n\nAbstract: With the rapid growth of data traffic in cellular networks, edge caching has become an emerging technology for traffic offloading. We investigate the caching placement and content delivery in cache-enabling cellular networks. To cope with the time-varying content popularity and user location in practical scenarios, we formulate a long-term joint dynamic optimization problem of caching placement an...","Title: Blockage-Aware Beamforming Design for Active IRS-Aided mmWave Communication Systems\nYear: 2022\n\nAbstract: In this paper, we investigate a robust beamforming design in a millimeter wave (mmWave) communication network with consideration of the random blockages. The network with multiple remote radio units (RRUs) is taken into account, where the joint transmission coordinated multi-point (JT-CoMP) scheme is adopted to improve the spectrum efficiency. To further enhance the communication performance and maintain the reliability of the network, an active intelligent reflecting surface (IRS) panel is deployed. We formulate the robust beamforming design of the mmWave communication network as an optimization problem aiming at minimizing the total transmit power at the RRUs subject to the average signal-to-interference-plus-noise ratio (SINR) constraints and power constraint over the active IRS. To deal with the challenge caused by the variables coupling, an algorithm based on the alternating optimization (AO) and semidefinite programming (SDP) is proposed. Numerical results illustrate that: i) the transmit power of the network can be reduced by deploying both the passive and active IRSs; ii) the integration of the active IRS and CoMP scheme can obtain a significant performance gain compared to that of the conventional passive IRS and CoMP.","Title: Artificial Noise Aided Secure NOMA Communications in STAR-RIS Networks\nYear: 2022\n\nAbstract: Combination of simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) and non-orthogonal multiple access (NOMA) is a win-win strategy which can significantly enhance the coverage performance. However, eavesdroppers may enjoy similar performance gains as the legitimate users. To solve this problem, an artificial noise (AN) assisted secure communication strategy is proposed to maximize the secrecy rate. An alternating optimization (AO) based iterative algorithm leveraging the classical successive convex approximation (SCA) and the semidefinite relaxation (SDR) techniques is proposed to derive the optimal AN model and the RIS parameters. It is found that the proposed algorithm provides better secrecy performance with less AN power compared with the benchmark schemes. More RIS elements help reducing the AN power, while this effect shrinks when the number of RIS elements is sufficiently large. Increasing the number of transmit antennas reduces the AN power if the eavesdropper is quite close to the transmitter, while improves it when the eavesdropper is far away.","Title: Reconfigurable Intelligent Surface-Aided Multi-User Networks: Interplay Between NOMA and RIS\nYear: 2022\n\nAbstract: This article focuses on the exploitation of reconfigurable intelligent surfaces (RISs) in multiuser networks employing orthogonal multiple access (OMA) or non-orthogonal multiple access (NOMA), with an emphasis on investigating the interplay between NOMA and RIS. Depending on whether the RIS reflection coefficients can be adjusted only once or multiple times during one transmission, we distinguish between static and dynamic RIS configurations. In particular, the capacity region of RIS-aided single-antenna NOMA networks is discussed and compared with the OMA rate region from an information-theoretic perspective, revealing that the dynamic RIS configuration is capacity-achieving. Then, the impact of the RIS deployment location on the performance of different multiple access schemes is investigated, which reveals that asymmetric and symmetric deployment strategies are preferable for NOMA and OMA, respectively. Furthermore, for RIS-aided multiple-antenna NOMA networks, three novel joint active and passive beamformer designs are proposed based on both beamformer-based and cluster-based strategies. Finally, open research problems for RIS-NOMA networks are highlighted.","Title: Simultaneously Transmitting and Reflecting Intelligent Omni-Surfaces: Modeling and Implementation\nYear: 2022\n\nAbstract: Given the rapid development of advanced electromagnetic (EM) manipulation technologies, researchers have turned their attention to the investigation of smart surfaces for enhancing radio coverage. Simultaneously transmitting and reflecting (STAR) intelligent omni-surfaces (IOSs) constitute one of the most promising categories. Although previous research contributions have demonstrated the benefits of simultaneously transmitting and reflecting intelligent omni-surfaces (STAR-IOSs) in terms of wireless communication performance gains, several important issues remain unresolved, including practical hardware implementations and accurate physical models. In this article, we address these by discussing four practical hardware implementations of STAR-IOSs as well as three hardware modeling techniques and five channel modeling methods. We thus clarify the taxonomy of smart surface technologies in support of further investigating the family of STAR-IOSs.","Title: Federated Learning in Multi-RIS-Aided Systems\nYear: 2022\n\nAbstract: The fundamental communication paradigms in the next-generation mobile networks are shifting from connected things to connected intelligence. The potential result is that current communication-centric wireless systems are greatly stressed when supporting computation-centric intelligent services with distributed big data. This is one reason that makes federated learning come into being, it allows collaborative training over many edge devices while avoiding the transmission of raw data. To tackle the problem of model aggregation in federated learning systems, this article resorts to multiple reconfigurable intelligent surfaces (RISs) to achieve efficient and reliable learning-oriented wireless connectivity. The seamless integration of communication and computation is actualized by over-the-air computation (AirComp), which can be deemed as one of the uplink nonorthogonal multiple access (NOMA) techniques without individual information decoding. Since all local parameters are uploaded via noisy concurrent transmissions, the unfavorable propagation error inevitably deteriorates the accuracy of the aggregated global model. The goals of this work are to 1) alleviate the signal distortion of AirComp over shared wireless channels and 2) speed up the convergence rate of federated learning. More specifically, both the mean-square error (MSE) and the device set in the model uploading process are optimized by jointly designing transceivers, tuning reflection coefficients, and selecting clients. Compared to baselines, extensive simulation results show that 1) the proposed algorithms can aggregate model more accurately and accelerate convergence and 2) the training loss and inference accuracy of federated learning can be improved significantly with the aid of multiple RISs.","Title: Ergodic Rate Analysis of STAR-RIS Aided NOMA Systems\nYear: 2022\n\nAbstract: This letter analyzes the ergodic rates of a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided non-orthogonal multiple access (NOMA) system, where the direct links from the base station to cell-edge users are non-line-of-sight due to obstacles, and STAR-RIS is used to provide line-of-sight links to these cell-edge users. By fitting the distribution of the composite channel power gain to a gamma distribution, we derive the closed-form expressions of ergodic rates and high signal-to-noise ratio (SNR) slopes for cell-edge users. Numerical results reveal that 1) the ergodic rates increase with the number of STAR-RIS elements, and the high SNR slopes are fixed as constants; 2) STAR-RIS aided NOMA systems achieve higher ergodic rates than conventional RIS aided NOMA systems.","Title: Performance Analysis for the Coupled Phase-Shift STAR-RISs\nYear: 2022\n\nAbstract: In this work, we focus on simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) with coupled transmission and reflection phase shifts. We demonstrate how to achieve full diversity for users on both sides by proposing a practical phase-shift design, namely, the diversity preserving design. To evaluate the performance, a STAR-RIS-aided two-user downlink communication system is investigated for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA). The outage probabilities, diversity orders, and power scaling laws under this design are studied and compared with the performance upper and lower bounds. Numerical simulations show that the proposed diversity preserving phase-shift configuration strategy for the STAR-RIS achieves the same diversity order as the STAR-RISs assuming independent phase-shift, and achieves a comparable power scaling law with only 4 dB power reduction.","Title: Downlink Multi-RIS Aided Transmission in Backhaul Limited Networks\nYear: 2022\n\nAbstract: This letter proposes an analytical framework for multi-reconfigurable intelligent surface (RIS) aided networks with limited backhaul capacity, where a simple symmetric structure is considered to explore the characteristics of multi-RIS systems with coherent transmissions. By using the Gamma distribution to model the composite RIS-aided channels, closed-form expressions in terms of the outage probability and the ergodic rate are derived. The theoretical results provide two design guidelines: 1) the minimum outage can be achieved by deploying the assisted RISs at certain locations; 2) the rate performance is bounded, and an optimal number of assisted RISs exists for rate maximization. Simulations verify our analysis and demonstrate the backhaul capacity is the bottleneck for multi-RIS systems. Compared with single-RIS systems, multi-RIS systems require a minimal backhaul capacity to ensure the performance gain.","Title: UAV-Enabled Non-Orthogonal Multiple Access Networks for Ground-Air-Ground Communications\nYear: 2022\n\nAbstract: Both unmanned aerial vehicle (UAV) and non-orthogonal multiple access (NOMA) have gradually become promising technologies for the fifth generation (5G) driven green Internet-of-Things (IoT) networks on account of their unique advantages of massive connections, higher spectral efficiency and flexibility. Motivated by this, we propose a 3-hop NOMA UAV-aided green communication network framework, where UAVs serve as aerial relays to support two groups of ground users. A stochastic geometry approach is invoked to model the spatial positions of the two group users. Under the realistic assumption, imperfect successive interference cancelation (ipSIC) is considered. To evaluate the performance of the proposed framework, theoretical expressions are derived to facilitate the outage performance evaluation of the far user (FU) and the near user (NU). Moreover, the asymptotic behaviors for the outage probability (OP) of both the FU and the NU in the high signal-to-noise ratio (SNR) regime are explored by obtaining diversity orders. Finally, the system throughputs under the delay-limited transmission mode are investigated. Numerical results confirm that: 1) For uplink transmission, there exist outage floors for the OP of both ipSIC and perfect SIC (pSIC) due to interference from the NU; 2) For downlink transmission, an outage floor exists for the OP of the NU under the condition of ipSIC; 3) For uplink NOMA/orthogonal multiple access (OMA) transmission, the outage performances of both the FU and the NU with NOMA outperform OMA in the low SNRs, while OMA has better performance in the high SNR regime; 4) For downlink NOMA/OMA, the outage performances of both the FU and the NU under pSIC outperform OMA.","Title: Effective Capacity Analysis of STAR-RIS-Assisted NOMA Networks\nYear: 2022\n\nAbstract: This letter studies the performance of the simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided non-orthogonal multiple access (NOMA) networks in support of ultra-reliable low-latency communications. We adopt effective capacity (EC) as the metric to explore the delay requirements of NOMA users. Specifically, the analytical expressions of the EC are obtained for the network with a pair of NOMA users on the different sides of the STAR-RIS. Furthermore, the high signal-to-noise ratio (SNR) slope and high SNR power offset are invoked to provide asymptotic analysis of the ECs in high SNR. Some insightful conclusions are drawn from the simulations: 1) the EC of near user \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$({U_{n}})$ </tex-math></inline-formula>\n increases linearly while the EC of far user \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$({U_{m}})$ </tex-math></inline-formula>\n tends to be a constant in the high SNR; 2) comparing with STAR-orthogonal multiple access and conventional RIS, the use of STAR-RIS NOMA increases the ECs of \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">${U_{n}}$ </tex-math></inline-formula>\n and overall network; 3) increasing the number of STAR-RIS elements is an effective strategy to improve the ECs of both \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">${U_{n}}$ </tex-math></inline-formula>\n and \n<inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">${U_{m}}$ </tex-math></inline-formula>\n.","Title: Computation Capacity Enhancement by Joint UAV and RIS Design in IoT\nYear: 2022\n\nAbstract: Mobile-edge computing (MEC) networks are facing limited coverage and harsh wireless transmission environments that severely hinder the computation capacity of the Internet-of-Things (IoT) devices. To overcome these issues, this article proposes a novel MEC framework empowered by an unmanned aerial vehicle (UAV) relay and a reconfigurable intelligence surface (RIS). To fully exploit the potentials in terms of computation enhancement brought by the joint UAV and RIS design, we formulate a max–min computation capacity problem via determining the uplink signal detection, active beamforming of UAV, passive beamforming of RIS, time slot partition, computation bits of UAV, and UAV’s trajectory. We develop a concave–convex procedure (CCCP)-based algorithm in an alternating optimization manner over three subproblems to solve the formulated problem. It finds that the CCCP-based algorithm is conducive to decouple the intractable expressions by converting them into new but tractable second-order cone (SOC) constrains. To evaluate the performance of the proposed CCCP-based algorithm, we later design a direct algorithm by exploiting the implicit convexity of the problem. Simulation results demonstrate that the proposed CCCP-based algorithm derives a comparable performance as the direct algorithm, and achieves about 2.57-Mb max-min computation capacity higher compared with the straight flight case, and 8.08-Mb max–min computation capacity higher compared with the case without RIS, which validate the superiority of the joint UAV and RIS design for computation enhancement.","Title: Cellular-Connected Multi-UAV MEC Networks: An Online Stochastic Optimization Approach\nYear: 2022\n\nAbstract: In this paper, we consider a mobile edge computing (MEC) network where multiple cellular-connected unmanned aerial vehicles (UAVs) can offload their computation tasks to multiple ground base stations (GBSs). In practice, the UAVs are generally unable to master stochastic information of task arrival and channel changes in advance, which may cause a severe issue in terms of energy consumption. Therefore, we formulate a stochastic optimization problem with the goal of minimizing the average weighted sum energy consumption, by jointly optimizing UAV-GBS associations, communication and computation resource allocation, and three-dimensional (3D) UAV trajectories, during which a velocity-triggered penalty term (VTPT) is designed to suppress a large amount of the energy consumption of the UAVs. To handle the stochastic problem, we propose an online resource allocation and trajectory optimization algorithm with outer and inner structures. The outer structure transforms the original problem to a deterministic one by applying the Lyapunov-based optimization framework. The inner structure solves the obtained deterministic problem via the Lagrange duality method and the successive convex approximation technique, based on the block coordinate descent framework. Numerical results demonstrate that: 1) VTPT dramatically decreases the UAVs’ energy consumption, and 2) the proposed algorithm not only reduces the energy consumption but also ensures the computation queue stability compared with other benchmark schemes.","Title: How Can Reconfigurable Intelligent Surfaces Drive 5G-Advanced Wireless Networks: A Standardization Perspective\nYear: 2022\n\nAbstract: The reconfigurable intelligent surface (RIS) is a promising technology for achieving smart radio environment in future wireless networks with significantly reduced cost. While most existing works focused on several theoretical challenges of RIS empowered wireless communication systems, the engineering and standardization aspects taking into account practical implementation constraints regarding deployment costs and compatibility have not been investigated clearly yet. To fill this gap, this paper provides an overview of the RIS enabled opportunities for the fifth generation (5G) Advanced and also highlight the critical requirements and challenges from a standardization perspective. In particular, the use cases and deployment of RIS, the realistic channel models, the smart RIS control, and the interference management of multiple RISs are elaborated."],"string":"[\n \"Title: Automatic game AI design by the use of UCT for Dead-End\\nYear: 2010\\n\\nAbstract: Video game AI aims at generating an intelligent game opponent which is to compete with player, so game AI design plays an important role in the development of game. Nowadays, most of the game AI is implemented by FSM. But this mechanism has some drawbacks, so we need a mechanism to design game AI automatically instead of FSM. The process of automatic game AI design by UCT is introduced in this paper. In this process, we only take the meta-rules into consideration, while those many complicated detail knowledge is acquired by simulation. Here we propose the approach of UCT-controlled NPC based on CI (computational intelligence). However, this approach will consume lots of computational resources, and the acquired knowledge cannot be stored. To solve this problem, we train Artificial Neural Network (ANN) to make it reusable. The whole design process is validated on the Test-Bed of the game Dead-End. We conclude that from both the simplification of implementation and the reusability, this process outperforms FSM.\",\n \"Title: Relay Selection for Security Enhancement in Cognitive Relay Networks\\nYear: 2015\\n\\nAbstract: This letter proposes several relay selection policies for secure communication in cognitive decode-and-forward relay networks, where a pair of cognitive relays is opportunistically selected for security protection against eavesdropping. The first relay transmits the secrecy information to the destination, and the second relay, as a friendly jammer, transmits the jamming signal to confound the eavesdropper. We present new exact closed-form expressions for the secrecy outage probability. Our analysis and simulation results strongly support our conclusion that the proposed relay selection policies can enhance the performance of secure cognitive radio. We also confirm that the error floor phenomenon is created in the absence of jamming.\",\n \"Title: Wireless Energy Harvesting and Spectrum Sharing in Cognitive Radio\\nYear: 2014\\n\\nAbstract: A wireless energy harvesting protocol is proposed for a decode-and-forward relay- assisted secondary user (SU) network in a cognitive spectrum sharing paradigm. An expression for the outage probability of the relay-assisted cognitive network is derived subject to the following power constraints: 1) the maximum power that the source and the relay in the SU network can transmit from the harvested energy, 2) the peak interference power from the source and the relay in the SU network at the primary user (PU) network, and 3) the interference power of the PU network at the relay-assisted SU network. The results show that as the energy harvesting conversion efficiency improves, the relay- assisted network with the proposed wireless energy harvesting protocol can operate with outage probabilities below 20% for some practical applications.\",\n \"Title: Two-way relaying networks with wireless power transfer: Policies design and throughput analysis\\nYear: 2014\\n\\nAbstract: This paper exploits an amplify-and-forward (AF) two-way relaying network (TWRN), where an energy constrained relay node harvests energy with wireless power transfer. Two bidirectional protocols, multiple access broadcast (MABC) protocol and time division broadcast (TDBC) protocol, are considered. Three wireless power transfer policies, namely, dual-source (DS) power transfer; single-fixed-source (SFS) power transfer; and single-best-source (SBS) power transfer are proposed and well-designed based on time switching receiver architecture. We derive analytical expressions to determine the throughput both for delay-limited transmission and delay-tolerant transmission. Numerical results corroborate our analysis and show that MABC protocol achieves a higher throughput than TDBC protocol. An important observation is that SBS policy offers a good tradeoff between throughput and power.\",\n \"Title: Wireless Energy Harvesting in a Cognitive Relay Network.\\nYear: 2016\\n\\nAbstract: Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with multiple primary user (PU) transceivers. In this protocol, the secondary nodes can harvest energy from the primary network (PN) while sharing the licensed spectrum ...\",\n \"Title: Secure D2D Communication in Large-Scale Cognitive Cellular Networks: A Wireless Power Transfer Model.\\nYear: 2016\\n\\nAbstract: In this paper, we investigate secure device-to-device (D2D) communication in energy harvesting large-scale cognitive cellular networks. The energy constrained D2D transmitter harvests energy from multiantenna equipped power beacons (PBs), and communicates with the corresponding receiver using the spectrum of the primary base stations (BSs). We introduce a power transfer model and an information si...\",\n \"Title: Throughput Analysis of Wireless Powered Cognitive Radio Networks with Compressive Sensing and Matrix Completion.\\nYear: 2016\\n\\nAbstract: In this paper, we consider a cognitive radio network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure is proposed for the considered network. A wireless power transfer (WPT) model and a compressive spectrum sensing model are introduced. In the WPT model, a new WPT scheme is proposed, and the closed-form expressions for the power outage probability are derived. In compressive spectrum sensing model, two scenarios are considered: 1) Single SU, and 2) Multiple SUs. In the single SU scenario, in order to reduce the energy consumption at the SU, compressive sensing technique which enables sub-Nyquist sampling is utilized. In the multiple SUs scenario, cooperative spectrum sensing (CSS) is performed with adopting low-rank matrix completion technique to obtain the complete matrix at the fusion center. Throughput optimizations of the secondary network are formulated into two linear constrained problems, which aim to maximize the throughput of single SU and the CSS networks, respectively. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power. Simulation results show that: 1) Multiple SUs scenario can achieve lower power outage probability than single SU scenario; and 2) The optimal throughput can be improved by implementing compressive spectrum sensing in the proposed frame structure design.\",\n \"Title: Application of Non-orthogonal Multiple Access in LTE and 5G Networks.\\nYear: 2017\\n\\nAbstract: As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP LTE and is envisioned to be an essential component of 5G mobile networks. The key feature of NOMA is to serve multiple users at the same time/frequency/ code, but with different power levels, which yields a significant spectral efficiency gain over conventional orthogonal MA. The article provides a systematic treatment of this newly emerging technology, from its combination with MIMO technologies to cooperative NOMA, as well as the interplay between NOMA and cognitive radio. This article also reviews the state of the art in the standardization activities concerning the implementation of NOMA in LTE and 5G networks.\",\n \"Title: Improvements Of Robot Positioning Accuracy And Drilling Perpendicularity For Autonomous Drilling Robot System\\nYear: 2015\\n\\nAbstract: The low accuracy of Autonomous Drilling Robot System (ADRS) has precluded their usage in aircraft assembly. Aiming at improving the accuracy of ADRS, three efforts are made in this paper. Firstly, a novel surface normal measurement and attitude adjusting method are proposed to guarantee the perpendicularity of holes. Secondly, an improvement compensation method is made for absolute positioning accuracy of industrial robot by using Gauss-Newton method. Thirdly, during the calibration of tool center point(TCP), which is one of the key technologies of offline programming control system, two balls are used in this method to solve the problem of low accuracy and inefficiency of traditional method using pointed end. Finally, both simulations and experiments are conducted to test the effect of the improvements and the results prove the improvements are effective.\",\n \"Title: Cooperative non-orthogonal multiple access in 5G systems with SWIPT\\nYear: 2015\\n\\nAbstract: In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) is investigated. A new cooperative SWIPT NOMA protocol is proposed in which near NOMA users which arc close to the source act as energy harvesting relays to help far NOMA users. By assuming that all users are spatially randomly located in the network, new analytical expressions for outage probability are derived both for the near and far users, in order to characterize the performance of the proposed protocol. The diversity of both the near and far users is analyzed to demonstrate that the use of SWIPT will not jeopardize the diversity order compared to the conventional NOMA. Numerical results are also provided to verify the accuracy of the developed analytical results.\",\n \"Title: Throughput Analysis for Compressive Spectrum Sensing with Wireless Power Transfer.\\nYear: 2015\\n\\nAbstract: In this paper, we consider a cognitive radio (CR) network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure which includes four time slots, namely, energy harvesting, spectrum sensing, energy harvesting and data transmission is proposed. In the energy harvesting slot, a new wireless power transfer (WPT) scheme in a bounded power transfer model is proposed to enable power SUs wirelessly. Closed-form expressions for the power outage probability of the proposed WPT scheme are derived. In the spectrum sensing slot, we propose to utilize the compressive sensing (CS) technique which enables sub-Nyquist sampling to further reduce the energy consumption at SUs. Throughput of the secondary network with the proposed frame structure is formulated into a nonlinear constraint problem. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power.\",\n \"Title: Fairness of User Clustering in MIMO Non-Orthogonal Multiple Access Systems.\\nYear: 2016\\n\\nAbstract: In this letter, a downlink multiple-input-multiple-output non-orthogonal multiple access scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this optimization problem, three sub-optimal algorithms, namely, top-down A, top-down B, and bottom up, are proposed to realize the different tradeoffs of complexity and throughput of the worst user. In addition, for each given user clustering case, we optimize the power allocation coefficients for the users in each cluster by adopting a bisection search-based algorithm. Numerical results show that the proposed algorithms can lower the complexity with an acceptable degradation on the throughput compared with the exhaustive search method. It is worth noting that the top-down B algorithm can achieve a good tradeoff between the complexity and the throughput among the three proposed algorithms.\",\n \"Title: Physical layer security for 5G non-orthogonal multiple access in large-scale networks\\nYear: 2016\\n\\nAbstract: In this paper, the physical layer security of applying non-orthogonal multiple access (NOMA) in large-scale networks is investigated. In the considered scenario, both the NOMA users and eavesdroppers are spatially randomly deployed. A protected zone around the source node is adopted to enhance the security of a random network. In order to characterize the secrecy performance of the considered scenario, new exact and asymptotic expressions for the security outage probability are derived. These analytical results demonstrate that the secrecy diversity order is m, which is determined by the user with poor channel condition. Monte Carlo simulations are provided to verify the derived analytical results. Furthermore, it is also confirmed that the secure performance of the NOMA networks can be improved by either enlarging the scope of the protected zone or reducing the scope of the user zone.\",\n \"Title: Two-way relay networks with wireless power transfer: design and performance analysis.\\nYear: 2016\\n\\nAbstract: This study considers amplify-and-forward two-way relay networks, where an energy constrained relay node harvests energy from the received radio-frequency signal. Based on time switching receiver, they separate the energy harvesting (EH) phase and the information processing (IP) phase in time. In the EH phase, three practical wireless power transfer policies are proposed: (i) dual-source (DS) power...\",\n \"Title: Many-to-Many Matching With Externalities for Device-to-Device Communications\\nYear: 2017\\n\\nAbstract: In this letter, we aim to solve the resource allocation problem for device-to-device (D2D) communications underlaying cellular networks. Particularly, multiple D2D pairs are allowed to reuse the same resource block (RB), and one D2D pair is allowed to use the spectrum of multiple RBs. Our objective is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise ratio constraints for both D2D and cellular user equipments. In order to solve this non-deterministic polynomial-time hard optimization problem, we propose a novel algorithm for obtaining a sub-optimal solution based on the many-to-many two-sided matching game with externalities. To characterize the properties of the proposed algorithm, we prove that it converges to the two-sided exchange stability within a limited number of iterations. Additionally, simulation results show that the proposed algorithm can achieve the near-optimal system sum rate and significantly outperforms a one-to-one matching algorithm.\",\n \"Title: Enhancing the Physical Layer Security of Non-orthogonal Multiple Access in Large-Scale Networks.\\nYear: 2017\\n\\nAbstract: This paper investigates the physical layer security of non-orthogonal multiple access (NOMA) in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered, where the base station (BS) communicates with randomly distributed NOMA users. In the single-antenna scenario, we adopt a protected zone around the BS to establish an eavesdropper-exclusion area with the aid of careful channel ordering of the NOMA users. In the multiple-antenna scenario, artificial noise is generated at the BS for further improving the security of a beamforming-aided system. In order to characterize the secrecy performance, we derive new exact expressions of the security outage probability for both single-antenna and multiple-antenna aided scenarios. For the single-antenna scenario, we perform secrecy diversity order analysis of the selected user pair. The analytical results derived demonstrate that the secrecy diversity order is determined by the specific user having the worse channel condition among the selected user pair. For the multiple-antenna scenario, we derive the asymptotic secrecy outage probability, when the number of transmit antennas tends to infinity. Monte Carlo simulations are provided for verifying the analytical results derived and to show that: 1) the security performance of the NOMA networks can be improved by invoking the protected zone and by generating artificial noise at the BS and 2) the asymptotic secrecy outage probability is close to the exact secrecy outage probability.\",\n \"Title: NOMA-Based D2D Communications: Towards 5G.\\nYear: 2016\\n\\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA)-based device-to-device (D2D) communications framework is proposed. A major novelty of the proposed framework is that it introduces the new concept of \\\"D2D group\\\" which utilizes NOMA transmission, enabling one D2D transmitter to communicate with multiple D2D receivers simultaneously. Based on the considered framework, a resource allocation optimization problem is formulated, where multiple D2D groups are allowed to reuse the same subchannel. The objective of this work is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise (SINR) constraints of both D2D and traditional cellular users. Note that the formulated problem is non-deterministic polynomial-time (NP) hard in nature, thus a novel resource allocation algorithm based on the many-to-one two-sided matching theory is proposed for obtaining a suboptimal solution. It is proved that the proposed algorithm converges to a stable state within limited number of iterations. Numerical results illustrate that: i) the proposed algorithm is an effective approach for obtaining near-optimal performance with acceptable complexity; and ii) the proposed NOMA-based D2D framework is capable of achieving promising gains over traditional orthogonal multiple access (OMA)-based D2D framework.\",\n \"Title: Wireless Powered Cognitive Radio Networks With Compressive Sensing and Matrix Completion\\nYear: 2017\\n\\nAbstract: In this paper, we consider cognitive radio networks in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons. A new frame structure is proposed for the considered networks. In the considered network, a wireless power transfer model is proposed, and the closed-form expressions for the power outage probability are derived. In addition, in order to...\",\n \"Title: Performance Analysis of NOMA With Fixed Gain Relaying Over Nakagami-m Fading Channels.\\nYear: 2018\\n\\nAbstract: This paper studies the application of cooperative techniques for non-orthogonal multiple access (NOMA). More particularly, the fixed gain amplify-and-forward (AF) relaying with NOMA is investigated over Nakagami-m fading channels. Two scenarios are considered insightfully: 1) the first scenario is that the base station (BS) intends to communicate with multiple users through the assistance of AF relaying, where the direct links are existent between the BS and users and 2) the second scenario is that the AF relaying is inexistent between the BS and users. To characterize the performance of the considered scenarios, new closed-form expressions for both exact and asymptomatic outage probabilities are derived. Based on the analytical results, the diversity orders achieved by the users are obtained. For the first and second scenarios, the diversity order for the nth user are mu(n+ 1) and mu n, respectively. Simulation results unveil that NOMA is capable of outperforming orthogonal multiple access (OMA) in terms of outage probability and system throughput. It is also worth noting that NOMA can provide better fairness compared with conventional OMA. By comparing the two scenarios, cooperative NOMA scenario can provide better outage performance relative to the second scenario.\",\n \"Title: Non-orthogonal Multiple Access in Large-Scale Heterogeneous Networks.\\nYear: 2017\\n\\nAbstract: In this paper, the potential benefits of applying non-orthogonal multiple access (NOMA) technique in K -tier hybrid heterogeneous networks (HetNets) is explored. A promising new transmission framework is proposed, in which NOMA is adopted in small cells and massive multiple-input multiple-output (MIMO) is employed in macro cells. For maximizing the biased average received power for mobile users, a...\",\n \"Title: Optimal User Scheduling and Power Allocation for Millimeter Wave NOMA Systems.\\nYear: 2018\\n\\nAbstract: This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mm-Wave) communications by exploiting beamforming, user scheduling, and power allocation. Random beamforming is invoked for reducing the feedback overhead of the considered system. A non-convex optimization problem for maximizing the sum rate is formulated, which is proved to be NP-hard. The branch...\",\n \"Title: Modelling And Analysis Of Low-Power Wide-Area Networks\\nYear: 2017\\n\\nAbstract: In this paper, we investigate the uplink transmission performance of low-power wide-area networks (LPWANs) with regards to coexisting radio modules using LoRa as an example. In doing so we adopt a new topology to model the network where the node locations of the network of focus (LoRa) follow a Poisson cluster process (PCP) while other coexisting interfering radio modules follow a Poisson point process (PPP). To characterize the performance of the proposed model as well as obtain insights, both analytical and closed-form approximated expressions for coverage probability are derived. Based on this, area spectrum efficiency, and energy efficiency are further characterized. These results demonstrate the degree to which the performance, with regard to the aforementioned metrics, is capable of being enhanced through varying the density of the deployment of LoRa nodes around each LoRa receiver. Moreover, simulation results unveil that an optimal value of active LoRa nodes in each cluster exists that maximizes area spectrum efficiency.\",\n \"Title: Resource Allocation For Non-Orthogonal Multiple Access In Heterogeneous Networks\\nYear: 2017\\n\\nAbstract: In this paper, novel resource allocation design is investigated for NOMA-enhanced heterogeneous networks (Het-Nets), where small cell base stations (SBSs) are enabled to communicate with multiple small cell users (SCUs) via the NOMA protocol. The resource allocation problem with the aim of maximizing the sum rate of SCUs is formulated as a many-to-one matching game. Due to the existence of co-channel interference, this game is shown to belong to a class of matching games with peer effects. To solve this game, we propose a novel distributed algorithm where the SBSs and resource blocks (RBs) can interact to decide their desired allocation. The proposed algorithm is proved to converge to a two-sided exchange-stable matching with much lower complexity compared to the centralized method. Simulation results unveil that: 1) The proposed algorithm closely approaches the global optimal solution by around 92.5% within a limited number of iterations; and 2) The developed NOMA-enhanced HetNets scheme achieves a higher sum rate of SCUs compared to the traditional OMA-based HetNets scheme.\",\n \"Title: Joint Subchannel and Power Allocation for NOMA Enhanced D2D Communications.\\nYear: 2017\\n\\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA) enhanced device-to-device (D2D) communication scheme is considered. Our objective is to maximize the system sum rate by optimizing subchannel and power allocation. We propose a novel solution that jointly assigns subchannels to D2D groups and allocates power to receivers in each D2D group. For the subchannel assignment, a novel algorithm...\",\n \"Title: Nonorthogonal Multiple Access for 5G and Beyond.\\nYear: 2018\\n\\nAbstract: Driven by the rapid escalation of the wireless capacity requirements imposed by advanced multimedia applications (e.g., ultrahigh-definition video, virtual reality, etc.), as well as the dramatically increasing demand for user access required for the Internet of Things (IoT), the fifth-generation (5G) networks face challenges in terms of supporting large-scale heterogeneous data traffic. Nonorthog...\",\n \"Title: Spectrum Allocation and Power Control for Non-Orthogonal Multiple Access in HetNets.\\nYear: 2017\\n\\nAbstract: In this paper, a novel resource allocation design is investigated for non-orthogonal multiple access (NOMA) enhanced heterogeneous networks (HetNets), where small cell base stations (SBSs) are capable of communicating with multiple small cell users (SCUs) via the NOMA protocol. With the aim of maximizing the sum rate of SCUs while taking the fairness issue into consideration, a joint problem of sp...\",\n \"Title: Joint Pilot Allocation and Robust Transmission Design for Ultra-dense User-centric TDD C-RAN with Imperfect CSI.\\nYear: 2018\\n\\nAbstract: This paper considers the unavailability of complete channel state information (CSI) in ultra-dense cloud radio access networks. The user-centric cluster is adopted to reduce the computational complexity, while the incomplete CSI is considered to reduce the heavy channel training overhead, where only large-scale inter-cluster CSI is available. Channel estimation for intra-cluster CSI is also consid...\",\n \"Title: Uplink NOMA in Large-Scale Systems: Coverage and Physical Layer Security.\\nYear: 2017\\n\\nAbstract: In this paper, the physical layer security of uplink non-orthogonal multiple access (NOMA) in large-scale networks is analyzed. An stochastic geometry approach is applied to derive new analytical expressions for the coverage probability and the effective secrecy throughput (EST) of the kth NOMA user, which may use a fixed or an adaptive transmission rate. We consider a protected zone around the legitimate terminals to establish an eavesdropper-exclusion area. We assume that the channel state information associated with eavesdroppers is not available at the base station. The impact of an imperfect successive interference cancellation is also taken into account in this work. Our analysis allows an easy selection of the wiretap code rates that maximizes the EST. In addition, our framework also allows an optimum selection of other system parameters like the transmit power or the eavesdropper-exclusion radius.\",\n \"Title: Joint Pilot Allocation and Robust Beam-Vector Design for Ultra-Dense TDD C-RAN.\\nYear: 2017\\n\\nAbstract: This paper deals with the unavailability of full CSI in ultra-dense user-centric TDD C-RAN. To reduce the channel training overhead, we consider the incomplete CSI case, where only large-scale inter-cluster CSI is available. Channel estimation for intra-cluster CSI is also considered, where we formulate a joint pilot allocation and user equipment (UE) selection problem to maximize the number of admitted UEs with fixed number of pilots. A novel pilot allocation algorithm is proposed by considering the multi-UE pilot interference. Then, we consider robust beam-vector optimization problem subject to UEs' data rate requirements and fronthaul capacity constraints, where the channel estimation error and incomplete inter-cluster CSI are considered. Simulation results demonstrate its superiority over the existing algorithms.\",\n \"Title: Modeling and Analysis of NOMA Enabled CRAN with Cluster Point Process.\\nYear: 2017\\n\\nAbstract: In this paper, a novel non-orthogonal multiple access (NOMA)-enabled framework for cloud-radio access networks (CRANs) is proposed. In this framework, two users are scheduled in the same resources according to NOMA; however the performance of cell-edge users is enhanced by means of coordinating beamforming. Stochastic geometry is invoked for modeling the proposed framework, where the positions of BSs follow a cluster point process. In an effort to characterize the performance of the proposed framework, simple expressions in terms of outage probability are derived for both nearby users and the cell-edge users. It is analytically demonstrated that the average beamforming gain is a liner function with respect to the number of cooperating base stations. Numerical results verify the accuracy of analysis and reveal that the proposed framework is capable of greatly enhancing the performance of cell-edge users.\",\n \"Title: User Selection and Power Allocation for mmWave-NOMA Networks.\\nYear: 2017\\n\\nAbstract: This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mmWave) communication with beamforming, user selection and power allocation. To overcome the burden of feedback, random beamforming to mmWave NOMA systems is considered. We then formulate an optimization problem to maximize the sum rate of the proposed mmWave NOMA systems, which is nonconvex. To solve the challenging problem, we invoke the branch and bound (BB) technique to develop an optimal power allocation algorithm. Then a low complexity suboptimal algorithm based on matching theory is proposed to realize user selection. Simulation results are provided for validating the effectiveness of the proposed algorithms and to show that the sum rate performance of the mmWave NOMA systems can be substantially improved by the proposed algorithms compared to the conventional mmWave orthogonal multiple access (OMA) systems.\",\n \"Title: Full/Half-Duplex Relay Selection for Cooperative NOMA Networks.\\nYear: 2017\\n\\nAbstract: This paper investigates the impact of relay selection (RS) on the performance of cooperative non-orthogonal multiple access (NOMA), where relays are capable of working in either full-duplex (FD) or half-duplex (HD) mode. The locations of relays considered in the networks are modeled using stochastic geometry. The single-stage relay selection (SRS) scheme is proposed. In order to characterize the performance of SRS scheme, new closed-form expressions for both exact and asymptotic outage probabilities are derived. Based on the analytical results, the diversity orders achieved by the SRS scheme for FD/HD cooperative NOMA are obtained. It is confirmed that the FD-based SRS schemes obtain a zero diversity order, while the HD-based RS is capable of achieving a diversity order of K. Simulation results show that the outage performance of FD-based RS scheme outperforms HD-based RS scheme in the low signal-to-noise radio (SNR) region rather than in the high SNR region.\",\n \"Title: Training Based DOA Estimation in Hybrid mmWave Massive MIMO Systems.\\nYear: 2017\\n\\nAbstract: This paper proposes a novel direction of arrival (DOA) estimation for hybrid millimeter wave (mmWave) massive MIMO systems with the uniform planar array (UPA) at base station (BS). To explore the physical characteristics of antenna array in mmWave systems, the parameters of each channel path are decomposed into the DOA information and the channel gain information. We first estimate the initial DOAs of each uplink path through the two dimension discrete Fourier transform (2D-DFT) efficiently, and then the estimation accuracy can be further enhanced via the angle rotation technique. To examine the estimation performance, we derive the theoretical bounds of the mean squared error (MSE) performance of the DOA estimation in high signal-to-noise ratio (SNR) region. Simulation results are provided to corroborate the proposed studies, and show that the proposed DOA estimation method is close to the theoretical MSE performance.\",\n \"Title: Modeling and Analysis of D2D Millimeter-Wave Networks With Poisson Cluster Processes.\\nYear: 2018\\n\\nAbstract: This paper investigates the performance of millimeter wave (mmWave) communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process. In each cluster, devices are equipped with multiple antennas, and the active D2D transmitter (D2D-Tx) utilizes mmWave to serve one of the proximate D2D receivers. Specifically, we introduce three...\",\n \"Title: Cooperative Communications With Wireless Energy Harvesting Over Nakagami-m Fading Channels.\\nYear: 2017\\n\\nAbstract: In this paper, a dual-hop decode-to-forward cooperative system is considered where multiple relays are with finite energy storage and can harvest energy from the destination. In our analysis, the relays are spatially randomly located with invoking stochastic geometry. In an effort to improve spectral efficiency, an optimal source-relay link scheme is employed. Assuming Nakagami-m fading, two diffe...\",\n \"Title: Exploiting Full/Half-Duplex User Relaying in NOMA Systems.\\nYear: 2018\\n\\nAbstract: In this paper, a novel cooperative non-orthogonal multiple access (NOMA) system is proposed, where one near user is employed as decode-and-forward relaying switching between full-duplex (FD) and half-duplex (HD) mode to help a far user. Two representative cooperative relaying scenarios are investigated insightfully. The first scenario is that no direct link exists between the base station (BS) and...\",\n \"Title: User Association and Resource Allocation in Unified NOMA Enabled Heterogeneous Ultra Dense Networks\\nYear: 2018\\n\\nAbstract: Heterogeneous ultra dense networks (HUDNs) and non-orthogonal multiple access (NOMA) have been identified as two proposing techniques for 5G mobile communication systems due to their great capabilities to enhance spectrum efficiency. This article investigates the application of NOMA techniques in HUDNs to support massive connectivity in 5G systems. In particular, a unified NOMA framework is propos...\",\n \"Title: Toward Cross-Layer Design for Non-Orthogonal Multiple Access: A Quality-of-Experience Perspective.\\nYear: 2018\\n\\nAbstract: Recent years have seen a proliferation in versatile mobile devices and an upsurge in the growth of data-consuming application services. Orthogonal multiple access technologies in today's mobile systems are inefficient in the presence of such massive connectivity and traffic demands. In this regard, non-orthogonal multiple access has been advocated by the research community to embrace unprecedented...\",\n \"Title: Sparse Representation for Wireless Communications.\\nYear: 2018\\n\\nAbstract: Sparse representation can efficiently model signals in different applications to facilitate processing. In this article, we will discuss various applications of sparse representation in wireless communications, with a focus on the most recent compressive sensing (CS)-enabled approaches. With the help of the sparsity property, CS is able to enhance the spectrum efficiency (SE) and energy efficiency (EE) of fifth-generation (5G) and Internet of Things (IoT) networks.\",\n \"Title: Maximizing SINR for non-orthogonal multiple access with bounded channel uncertainties\\nYear: 2017\\n\\nAbstract: This letter examines the robust beamforming design multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) downlink systems with imperfect channel state information (ICSI). Sparked by the worst-case performance optimization framework, we consider to maximize the minimum of received signal-to-interference-plus-noise ratios (SINRs) of users, which is not convex with regards of beamforming vectors. The formulated optimization problem is not convex so, to solve the challengeable problem, we first formulate a equivalent optimization problem based on semidefinite programming (SDP). By applying a rank one relaxation and a linear matrix inequality (LMI) the S-Procedure can be used, which leads to exploiting bisection algorithm in order to obtaining the robust optimal beamforming solution. Finally, simulation results demonstrate the proposed design.\",\n \"Title: Sparse Representation for Wireless Communications: A Compressive Sensing Approach.\\nYear: 2018\\n\\nAbstract: Sparse representation can efficiently model signals in different applications to facilitate processing. In this article, we will discuss various applications of sparse representation in wireless communications, with a focus on the most recent compressive sensing (CS)-enabled approaches. With the help of the sparsity property, CS is able to enhance the spectrum efficiency (SE) and energy efficiency...\",\n \"Title: Modeling and Analysis of Clustered D2D Millimeter-Wave Communications\\nYear: 2018\\n\\nAbstract: This paper investigates the performance of millimeter wave communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process. In each cluster, the active D2D receiver (D2D-Rx) utilizes mmWave to communicate with one of proximate D2D transmitters (D2D-Txs). More specifically, we introduce two serving D2D-TX selection scenarios: 1) Uniformly distributed D2D-Tx model; 2) Closest line-of-site (LOS) D2D-Tx model. Moreover, we derive new analytical expressions for the coverage probability and area spectral efficiency (ASE). Monte Carlo simulations are provided to corroborate the theoretical results and show that: 1) The coverage probability is mainly affected by the LOS-interference; and 2) There exists an optimum number of simultaneously active D2D-Txs in each cluster for maximizing ASE.\",\n \"Title: Simultaneous Calibration of Hand-Eye Relationship, Robot-World Relationship and Robot Geometric Parameters with Stereo Vision.\\nYear: 2016\\n\\nAbstract: Robot-world calibration and hand-eye calibration are fundamental steps for robots equipped with cameras. This problem is described as solving \\\"AX = YB\\\" equation. However, this problem usually interacts with robot calibration, because robot geometric parameters are not very precise. Therefore, we propose a novel calibration method which can calibrate hand-eye relationship, robot-world relationship and robot geometric parameters simultaneously. This method considers hand-eye relationship and robot-world relationship as another two axes of robot arm. Modified D-H convention is used to describe robot position and orientation and stereo cameras are used to measure positioning errors. In order to improve calibration accuracy, least square method is introduced to solve calibration equations. Simulation and implement prove that this overall calibration method is feasible.\",\n \"Title: Multiple Antenna Aided NOMA in UAV Networks: A Stochastic Geometry Approach.\\nYear: 2019\\n\\nAbstract: This paper investigates the multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) assisted unmanned aerial vehicles (UAVs) networks. By utilizing a stochastic geometry model, a new 3-D UAV framework for providing wireless service to randomly roaming NOMA users has been proposed. In an effort to evaluate the performance of the proposed framework, we derive analytical expressions for the outage probability and the ergodic rate of MIMO-NOMA enhanced UAV networks. We examine tractable upper bounds for the whole proposed framework, with deriving asymptotic results for scenarios that transmit power of interference sources being proportional or being fixed to the UAV. For obtaining more insights for the proposed framework, we investigate the diversity order and high signal-to-noise slope of MIMO-NOMA assisted UAV networks. Our results confirm that: 1) Outage probability of NOMA enhanced UAV networks is affected to a large extent by the targeted transmission rates and power allocation factors of NOMA users and 2) For the case that the interference power is proportional to the UAV power, there are error floors for the outage probabilities.\",\n \"Title: Cache-enabled HetNets With Millimeter Wave Small Cells.\\nYear: 2018\\n\\nAbstract: In this paper, we consider a novel cache-enabled heterogeneous network (HetNet), where macro base stations (BSs) with traditional sub-6 GHz are overlaid by dense millimeter wave (mmWave) pico BSs. These two-tier BSs, which are modeled as two independent homogeneous Poisson point processes, cache multimedia contents following the popularity rank. High-capacity backhauls are utilized between macro B...\",\n \"Title: Spatially Random Relay Selection for Full/Half-Duplex Cooperative NOMA Networks.\\nYear: 2018\\n\\nAbstract: This paper investigates the impact of relay selection (RS) on the performance of cooperative non-orthogonal multiple access (NOMA), where relays are capable of working in either full-duplex (FD) or half-duplex (HD) mode. A number of relays (i.e., K relays) are uniformly distributed within the disc. A pair of RS schemes are considered insightfully: 1) single-stage RS (SRS) scheme; and 2) two-stage ...\",\n \"Title: Modeling and Analysis of Two-Way Relay Non-Orthogonal Multiple Access Systems.\\nYear: 2019\\n\\nAbstract: A two-way relay non-orthogonal multiple access (TWR-NOMA) system is investigated, where two groups of NOMA users exchange messages with the aid of one half-duplex decode-and-forward relay. Since the signal-plus-interference-to-noise ratios of NOMA signals mainly depend on effective successive interference cancellation (SIC) schemes, imperfect SIC (ipSIC), and perfect SIC (pSIC) are taken into acco...\",\n \"Title: QoE-Based Resource Allocation for Multi-Cell NOMA Networks.\\nYear: 2018\\n\\nAbstract: Quality of experience (QoE) is an important indicator in the fifth generation (5G) wireless communication systems. For characterizing user-base station (BS) association, subchannel assignment, and power allocation, we investigate the resource allocation problem in multi-cell multicarrier non-orthogonal multiple access (MC-NOMA) networks. An optimization problem is formulated with the objective of ...\",\n \"Title: A Unified Framework for Non-Orthogonal Multiple Access.\\nYear: 2019\\n\\nAbstract: This paper proposes a unified framework of non-orthogonal multiple access (NOMA) networks. Stochastic geometry is employed to model the locations of spatially NOMA users. The proposed unified NOMA framework is capable of being applied to both code-domain NOMA (CD-NOMA) and power-domain NOMA (PD-NOMA). Since the detection of NOMA users mainly depend on efficient successive interference cancelation ...\",\n \"Title: Joint Radio and Computational Resource Allocation for NOMA-Based Mobile Edge Computing in Heterogeneous Networks.\\nYear: 2018\\n\\nAbstract: A joint radio and computational resource allocation problem is investigated for non-orthogonal multiple access (NOMA)-based mobile edge computing (MEC) in heterogeneous networks (HetNets). The aim is to minimize the energy consumption of all users under the task execution latency constraint with partial task offloading. Due to the non-convexity of the formulated problem, we propose an iterative al...\",\n \"Title: Angle Domain Channel Estimation in Hybrid Millimeter Wave Massive MIMO Systems.\\nYear: 2018\\n\\nAbstract: This paper proposes a novel direction-of-arrival (DOA)-aided channel estimation for a hybrid millimeter-wave (mm-wave) massive multiple-input multiple-output system with a uniform planar array at the base station. To explore the physical characteristics of the antenna array in mm-wave systems, the parameters of each channel path are decomposed into the DOA information and the channel gain informat...\",\n \"Title: Trajectory tracking control method and experiment of AGV\\nYear: 2016\\n\\nAbstract: Aiming at the trajectory tracking control of AGV in aeronautical manufacturing and automated warehouse, a novel trajectory tracking control method was proposed. Firstly, the kinematic model and trajectory tracking control model of AGV were established. After analysing the reversing problem of AGV in practical situation and the limitations of classic trajectory tracking control method, and based on the similarity between the forward mode and reversing mode of AGV, a novel trajectory tracking control rule was designed and its stability was proved. The trajectory tracking control rule had simpler, less amount of calculation and improved the flexibility and handling efficiency of AGV. Finally, the trajectory tracking control experiments of sinusoid and path consisting of segments and arcs were done on experimental platform. The experiment results verified that the trajectory tracking control method were effective and feasible. The method could meet the requirements of autonomous handing for AGV in aeronautical manufacturing and automated warehouse.\",\n \"Title: A visual positioning and measurement system for robotic drilling\\nYear: 2016\\n\\nAbstract: In order to increase drilling efficiency, it is necessary for robotic drilling system to take advantage of offline programming method to drill a large number of holes automatically. Vision measurement is needed to correct work piece position because of inconformity between actual object and mathematical models. This paper introduces a visual positioning and measurement system for robotic drilling. A calibration board is designed to obtain hand-eye relationship and four laser range sensors are used to measure surface normal. This paper also summarizes workflow of offline programming and correction methods for different parts. Experiments give the result of hand-eye relationship and prove the position accuracy of vision measurement.\",\n \"Title: UAV Communications Based on Non-Orthogonal Multiple Access.\\nYear: 2019\\n\\nAbstract: This article proposes a novel framework for UAV networks with massive access capability supported by NOMA. In order to better understand NOMA-enabled UAV networks, three case studies are carried out. We first provide performance evaluation of NOMA-enabled UAV networks by adopting stochastic geometry to model the positions of UAVs and ground users. Then we investigate the joint trajectory design and power allocation for static NOMA users based on a simplified 2D model of UAV flying around at fixed height. As a further advance, we demonstrate the UAV placement issue with the aid of machine learning techniques when the ground users are roaming and the UAVs are capable of adjusting their positions in three dimensions accordingly. With these case studies, we can comprehensively understand the UAV systems from fundamental theory to practical implementation.\",\n \"Title: Multi-Pair Two-Way Massive MIMO Relaying with Hardware Impairments over Rician Fading Channels\\nYear: 2018\\n\\nAbstract: We consider a multi-pair two-way massive multiple-input multiple-out (MIMO) relaying system over Rician fading channels, where multi-pair users exchange their information via the amplify-and-forward (AF) relaying equipped with large number of antenna arrays. Hardware impairments at the relay and imperfect channel state information (CSI) are taken into account. More specifically, we derive a new linear minimum mean- square error (MMSE) channel estimator for the proposed system. It is demonstrated that normalized mean square error (NMSE) is a constant when the pilot power grows to infinity. Moreover, the asymptotic spectral efficiency with maximum ratio processing is presented in closed-form and the power scaling laws are analyzed. Simulation results indicates that massive MIMO is capable of compensating the loss caused by hardware impairments, estimation error and Rician fading.\",\n \"Title: Outage Performance of Cooperative NOMA Networks with Hardware Impairments.\\nYear: 2018\\n\\nAbstract: We investigate the outage performance of cooperative non-orthogonal multiple access (NOMA) networks with transceiver hardware impairments, where the estimated channel state information and alpha - mu fading channels are considered. Closed-form expressions for the outage probability of cooperative NOMA networks are derived for two representative scenarios. The first scenario is the base station (BS) directly communicates with NOMA users. The second scenario is BS communicates with NOMA users via the AF relaying. The diversity orders are presented for the two scenarios. It reveals that there is an error floor for the outage probability due to the distortion noise and estimation error.\",\n \"Title: Q-Learning for Content Placement in Wireless Cooperative Caching.\\nYear: 2018\\n\\nAbstract: Caching during off-peak times can bring popular contents closer to users, and hence improves quality of experience (QoE) of users in wireless networks. We formulate an optimization problem of cooperative content caching, with the aim of maximizing the sum mean opinion score (MOS) of all users in the network. To solve the challenging content caching problem, we cluster users by global kmeans (GKM), based on content popularity. For improving the effectiveness of caching, we propose a low complexity epsilon-greedy Q-learning based content caching algorithm which obtains near optimal solution. To characterize the performance of the proposed cooperative caching algorithms, sum MOS of users is used to define the reward function in Q-learning. The proposed Q-learning algorithm is capable of assisting the network to efficiently utilize the caching resource of the BSs. Simulation results reveal that: The proposed low complexity epsilon-greedy Q-learning based content caching algorithm achieves a near-optimal performance, and is capable of outperforming GKM based caching.\",\n \"Title: A Unified Spatial Framework for Clustered UAV Networks Based on Stochastic Geometry.\\nYear: 2018\\n\\nAbstract: To evaluate the system-level performance of clustered unmanned aerial vehicle (UAV) networks, we apply stochastic geometry in order to establish a tractable analytical framework. The users' locations are modeled as Poisson cluster processes (PCPs) and the UAVs are assumed to hover above cluster centers at a fixed altitude. In order to enhance the generality of the analysis, two typical patterns of PCPs, namely Thomas cluster process and Matern cluster process, are analyzed. Based on this spatial framework, a unified expression for the coverage probability is derived, for both millimeter wave (mmWave) and sub-6 GHz scenarios. Theoretical and numerical results demonstrate that mmWave outperforms sub-6 GHz, and an optimal altitude of UAVs exists, which maximizes the coverage probability. This result indicates that in most cases UAVs perform better than traditional terrestrial base stations, due to their mobility.\",\n \"Title: Mode Selection Between Index Coding and Superposition Coding in Cache-Based NOMA Networks\\nYear: 2019\\n\\nAbstract: By analytically showing that index coding (IC) is more power efficient than superposition coding (SC) when appropriate caching contents are available for a pair of users, we propose a sub-optimal joint user clustering and power allocation scheme for a single-cell downlink non-orthogonal multiple access network with caching memory at the receivers that alternate between IC and SC. Simulation studies demonstrate that the proposed scheme significantly reduces the transmission power when compared with the benchmark scheme that only allows SC.\",\n \"Title: Non-Orthogonal Multiple Access in Massive MIMO Aided Heterogeneous Networks.\\nYear: 2016\\n\\nAbstract: In this paper, the application of non-orthogonal multiple access (NOMA) into K-tier heterogeneous networks (HetNets) is investigated. A new promising transmission framework is proposed, in which massive multiple-input multiple-output (MIMO) is employed in macro cells and NOMA is adopted in small cells. For maximizing the biased average received power at mobile users, a massive MIMO and NOMA based user association scheme is developed. In an effort to evaluate the performance of the proposed framework, analytical expressions for the spectrum efficiency of each tier are derived using stochastic geometry. Simulation results are presented to verify the accuracy of the proposed analytical derivations and confirm that NOMA is capable of enhancing the spectrum efficiency of the network compared to the orthogonal multiple access (OMA) based HetNets.\",\n \"Title: Outage Performance Of Full/Half-Duplex User Relaying In Noma Systems\\nYear: 2017\\n\\nAbstract: This paper investigates the performance of cooperative non-orthogonal multiple access (NOMA) systems, where one near user works as a decode-and-forward (DF) full-duplex (FD) or half-duplex (HD) relaying to help far user. Two cooperative relay scenarios are considered insightfully. 1) The first scenario is that no direct link exists between the base station (BS) and the far user; and 2) The second scenario is that direct link exists between the BS and the far user. To characterize the performance of FD NOMA in two considered scenarios, new closed-form expressions for both exact and asymptotic outage probability as well as delay-limited throughput are derived for each NOMA user. Based on the analytical results derived, the diversity orders achieved by users are obtained. It is confirmed that the use of the direct link overcomes the zero diversity order of far NOMA user inherent to FD relaying. Simulation results demonstrate that the outage performance of FD NOMA is superior to HD NOMA at low SNR region rather than at high SNR region.\",\n \"Title: Performance Analysis of Non-Regenerative Massive-MIMO-NOMA Relay Systems for 5G.\\nYear: 2017\\n\\nAbstract: The non-regenerative massive multi-input-multioutput (MIMO) non-orthogonal multiple access (NOMA) relay systems are introduced in this paper. The NOMA is invoked with a superposition coding technique at the transmitter and successive interference cancellation (SIC) technique at the receiver. In addition, a maximum mean square error-SIC receiver design is adopted. With the aid of deterministic equi...\",\n \"Title: Multiple-Antenna-Assisted Non-Orthogonal Multiple Access.\\nYear: 2018\\n\\nAbstract: Non-orthogonal multiple access (NOMA) is potentially capable of circumventing the limitations of the classic orthogonal multiple access schemes. Hence, it has recently received significant research attention in both industry and academia. This article is focused on exploiting multiple antenna techniques in NOMA networks, with an emphasis on investigating the rate region of MIMO-NOMA, while reviewi...\",\n \"Title: Network Topology Optimization By Turning Non-Scale-Free Networks Into Scale-Free Networks Using Nonlinear Preferential Rewiring Method\\nYear: 2018\\n\\nAbstract: In practical application, the generation and evolution of many real networks always do not follow rigorous mathematical model, making network topology optimization a great challenge in the field of complex networks. In this research, we optimize the topology of non-scale-free networks by turning it into scale-free networks using a nonlinear preferential rewiring method. For different kinds of original networks generated by Watts and Strogatz model, we systematically demonstrate the optimization process and the modified networks to verify the performance of nonlinear preferential rewiring. We conduct further researches to explore the effect of nonlinear preferential rewiring's parameters on performance. Simulation results show that various non-scale-free networks with different network topologies generated by WS model, including random networks and various networks between regular and random, are turned into scale-free networks perfectly by nonlinear preferential rewiring method.\",\n \"Title: Energy-Efficient Hybrid Precoding for mmWave Massive MIMO Systems\\nYear: 2018\\n\\nAbstract: In millimeter Wave (mmWave) massive multi-input multi-output (MIMO) systems, the novel sub-connected architecture has been introduced which can further reduce power consumption compared with the fully-connected architecture. In this paper, we propose an energy-efficient hybrid precoding design with quality of service (QoS) constraints for sub-connected architecture. Firstly, the total energy efficiency optimization problem with nonconvex constraints is decomposed into two separate optimization sub-problems whose solution is a optimal single precoder respectively. Then, the first optimization sub-problem analog domain concerned is solved by a cross-entropy-based algorithm according to the machine learning theory. Finally, the second optimization sub-problem digital domain concerned is solved by an iterative optimization algorithm from fractional programming theory. Simulation results demonstrate that the performance of the proposed precoding algorithm. The performance of the proposed algorithm is capable of achieving near optimal solution. It is also demonstrated that the proposed algorithm can enhance the energy efficiency of networks while guaranteeing the QoS of users.\",\n \"Title: Spatio-temporal Correlated Channel Feedback for Massive MIMO Systems\\nYear: 2018\\n\\nAbstract: Accurate channel state information (CSI) at base station (BS) is the key to achieve full multiplexing and diversity gain in traditional multiple-input multiple-output (MIMO) systems. In frequency-division-duplex (FDD) systems, it is obtained through downlink training and uplink feedback. However, the training and feedback overhead in massive MIMO systems is unacceptable for the large number of antennas equipped at BS. To reduce the CSI feedback overhead and improve CSI quantization accuracy, we propose a limited feedback scheme for spatio-temporal correlated massive MIMO channel. The proposed scheme jointly performs Karhunen-Loève transform (KLT) and polar-cap quantization on CSI. For the compactly deployed antennas at BS, there exists spatial correlation in massive MIMO channel. When the user equipment (UE) moves slowly, adjacent channels feature temporal correlation. The high dimensional and spatial correlated CSI is compressed through KLT. Then the compressed CSI is normalized to be isotropic to perform polar-cap quantization. Simulation results show that the proposed scheme is capable of improving the sum-rate performance with limited feedback bits for massive MIMO systems.\",\n \"Title: Exploiting NOMA/OMA for Multi-UAV Communications in Large-Scale Networks.\\nYear: 2019\\n\\nAbstract: This paper advocates a pair of strategies in non-orthogonal multiple access (NOMA) in unmanned aerial vehicles (UAVs) communications, where multiple UAVs play as new aerial communications platforms for serving terrestrial NOMA users. A new multiple UAVs framework with invoking stochastic geometry technique is proposed, in which a pair of practical strategies are considered: 1) UAV-Centric strategy for offloading actions and 2) User-Centric strategy for providing emergency communications. In order to provide practical insights for the proposed NOMA assisted UAV framework, an imperfect successive interference cancelation (ipSIC) scenario is taken into account. For both UAV-Centric strategy and User-Centric strategy, we derive new exact expressions for the coverage probability. We also derive new analytical results for orthogonal multiple access (OMA) for providing a benchmark scheme. The derived analytical results in both User-Centric strategy and UAV-Centric strategy explicitly indicate that the ipSIC coefficient is a dominant component in terms of coverage probability. Numerical results are provided to confirm that i) for both User-Centric strategy and UAV-Centric strategy, NOMA assisted multi-UAV networks is capable of outperforming OMA by setting power allocation factors and targeted rate properly; and ii) the coverage probability of NOMA assisted multi-UAV framework is affected to a large extent by ipSIC coefficient, target rates and power allocations factors of paired NOMA users.\",\n \"Title: Trajectory Design and Power Control for Multi-UAV Assisted Wireless Networks: A Machine Learning Approach.\\nYear: 2019\\n\\nAbstract: A novel framework is proposed for the trajectory design of multiple unmanned aerial vehicles (UAVs) based on the prediction of usersu0027 mobility information. The problem of joint trajectory design and power control is formulated for maximizing the instantaneous sum transmit rate while satisfying the rate requirement of users. In an effort to solve this pertinent problem, a three-step approach is proposed which is based on machine learning techniques to obtain both the position information of users and the trajectory design of UAVs. Firstly, a multi-agent Q-learning based placement algorithm is proposed for determining the optimal positions of the UAVs based on the initial location of the users. Secondly, in an effort to determine the mobility information of users based on a real dataset, their position data is collected from Twitter to describe the anonymous user-trajectories in the physical world. In the meantime, an echo state network (ESN) based prediction algorithm is proposed for predicting the future positions of users based on the real dataset. Thirdly, a multi-agent Q-learning based algorithm is conceived for predicting the position of UAVs in each time slot based on the movement of users. The algorithm is proved to be able to converge to an optimal state. In this algorithm, multiple UAVs act as agents to find optimal actions by interacting with their environment and learn from their mistakes. Numerical results are provided to demonstrate that as the size of the reservoir increases, the proposed ESN approach improves the prediction accuracy. Finally, we demonstrate that throughput gains of about $17%$ are achieved.\",\n \"Title: Performance Analysis of FD-NOMA-based Decentralized V2X Systems\\nYear: 2019\\n\\nAbstract: In order to meet the requirements of massively connected devices, different quality of services (QoS), various transmit rates, and ultra-reliable and low latency communications (URLLC) in vehicle-to-everything (V2X) communications, we introduce a full duplex non-orthogonal multiple access (FD-NOMA)-based decentralized V2X system model. We, then, classify the V2X communications into two scenarios and give their exact capacity expressions. To solve the computation complicated problems of the involved exponential integral functions, we give the approximate closed-form expressions with arbitrary small errors. Numerical results indicate the validness of our derivations. Our analysis has that the accuracy of our approximate expressions is controlled by the division of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\frac {\\\\pi }{2}$ </tex-math></inline-formula>\\n in the urban and crowded scenarios, and the truncation point \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">${T}$ </tex-math></inline-formula>\\n in the suburban and remote scenarios. Numerical results manifest that: 1) increasing the number of V2X device, NOMA power, and Rician factor value yields a better capacity performance; 2) effect of FD-NOMA is determined by the FD self-interference and the channel noise; and 3) FD-NOMA has a better latency performance compared with other schemes.\",\n \"Title: Reinforcement Learning in Multiple-UAV Networks: Deployment and Movement Design.\\nYear: 2019\\n\\nAbstract: A novel framework is proposed for quality of experience (QoE)-driven deployment and dynamic movement of multiple unmanned aerial vehicles (UAVs). The problem of joint non-convex three-dimensional (3D) deployment and dynamic movement of the UAVs is formulated for maximizing the sum mean opinion score (MOS) of ground users, which is proved to be NP-hard. In the aim of solving this pertinent problem, a three-step approach is proposed for attaining 3D deployment and dynamic movement of multiple UAVs. Firstly, genetic algorithm based K-means (GAK-means) algorithm is utilized for obtaining the cell partition of the users. Secondly, Q-learning based deployment algorithm is proposed, in which each UAV acts as an agent, making their own decision for attaining 3D position by learning from trial and mistake. In contrast to conventional genetic algorithm based learning algorithms, the proposed algorithm is capable of training the direction selection strategy offline. Thirdly, Q-learning based movement algorithm is proposed in the scenario that the users are roaming. The proposed algorithm is capable of converging to an optimal state. Numerical results reveal that the proposed algorithms show a fast convergence rate after a small number of iterations. Additionally, the proposed Q-learning based deployment algorithm outperforms K-means algorithms and Iterative-GAKmean (IGK) algorithms with a low complexity.\",\n \"Title: Performance Analysis of Clustered LoRa Networks.\\nYear: 2019\\n\\nAbstract: In this paper, we investigate the uplink transmission performance of low-power wide-area (LPWA) networks with regards to coexisting radio modules. We adopt the long-range (LoRa) radio technique as an example of the network of focus, even though our analysis can be easily extended to other situations. We exploit a new topology to model the network, where the node locations of LoRa follow a Poisson cluster process while other coexisting radio modules follow a Poisson point process. Unlike most of the performance analysis based on stochastic geometry, we take noise into consideration. More specifically, two models, with a fixed and a random number of active LoRa nodes in each cluster, respectively, are considered. To obtain insights, both the exact and simple approximated expressions for coverage probability are derived. Based on them, area spectral efficiency and energy efficiency are obtained. From our analysis, we show how the performance of LPWA networks can be enhanced by adjusting the density of LoRa nodes around each LoRa receiver. Moreover, the simulation results unveil that the optimal number of active LoRa nodes in each cluster exists to maximize the area spectral efficiency.\",\n \"Title: Introduction to the Issue on Signal Processing Advances for Non-Orthogonal Multiple Access in Next Generation Wireless Networks.\\nYear: 2019\\n\\nAbstract: The papers in this special section focus on signal processing advances in non-orthogonal multiple access (NOMA) and network generation wireless networks. Recent years have witnessed the explosive growth ofmobile data traffic, which has led to ever-increasing demand for high system throughput, massive user access, heterogeneous data traffic, high bandwidth efficiency, and ultra-low latency. Non-ort...\",\n \"Title: Clustered Millimeter-Wave Networks With Non-Orthogonal Multiple Access\\nYear: 2019\\n\\nAbstract: We introduce clustered millimeter-wave (mmWave) networks with invoking non-orthogonal multiple access (NOMA) techniques, where the NOMA users are modeled as Poisson cluster processes and each cluster contains a base station (BS) located at the center. To provide realistic directional beamforming, an actual antenna array pattern is deployed at all BSs. We propose three distance-dependent user selection strategies to appraise the path loss impact on the performance of our considered networks. With the aid of such strategies, we derive tractable analytical expressions for the coverage probability and system throughput. Specifically, closed-form expressions are deduced under a sparse network assumption to improve the calculation efficiency. It theoretically demonstrates that the large antenna scale benefits the near user, while such influence for the far user is fluctuant due to the randomness of the beamforming. Moreover, the numerical results illustrate that: 1) the proposed system outperforms traditional orthogonal multiple access techniques and the commonly considered NOMA-mmWave scenarios with the random beamforming; 2) the coverage probability has a negative correlation with the variance of intra-cluster receivers; 3) 73 GHz is the best carrier frequency for the near user, and 28 GHz is the best choice for the far user; and 4) an optimal number of the antenna elements exists for maximizing the system throughput.\",\n \"Title: Joint Impact of Hardware Impairments and Imperfect Channel State Information on Multi-Relay Networks\\nYear: 2019\\n\\nAbstract: In this paper, we investigate the performance of dual-hop (DH) decode-and-forward (DF) multi-relay networks, for which two practical deleterious factors are taken into account, namely hardware impairments (HIs) and imperfect channel state information (ICSI). The communication between the source and the destination is realized with the aid of DF multi-relays, where both hops are assumed to be independent but non-identically distributed alpha-mu fading. Aiming at improving the system performance, three representative relay selection strategies are considered, in which the best relay is selected according to the link quality of source-to-relay and/or relay-to-destination. To characterize the performance of the proposed strategies, two key performance metrics, namely outage probability (OP) and ergodic capacity (EC), are analyzed insightfully. We first derive closed-form expressions for both exact and asymptotic OPs. Utilizing the derived results, diversity orders achieved at the destinations are obtained. We demonstrate that the OPs of considered networks are limited by HIs and ICSI, and the diversity orders are zeros due to the presence of ICSI. Then, we study the ECs of the proposed relay selection schemes, and upper bounds for the EC and asymptotic expressions for the EC in the high signal-to-noise ratio (SNR) regime are derived. To obtain more insights, the affine expansions for the EC are involved by two metrics of high-SNR slope and high-SNR power offset. It is shown that there are rate ceilings for the EC due to HIs and ICSI, which result in zero high-SNR slopes and finite high-SNR power offsets.\",\n \"Title: Uplink Non-Orthogonal Multiple Access for UAV Communications.\\nYear: 2019\\n\\nAbstract: This paper investigates ground-aerial uplink non-orthogonal multiple access (NOMA) cellular networks. A rotary-wing unmanned aerial vehicle (UAV) user and multiple ground users (GUEs) are served by ground base stations (GBSs) by utilizing uplink NOMA protocol. The UAV is dispatched to upload specific information bits to each target GBSs. Specifically, our goal is to minimize the UAV mission completion time by jointly optimizing the UAV trajectory and UAV-GBS association order while taking into account the UAV's interference to non-associated GBSs. The formulated problem is a mixed integer non-convex problem and involves infinite variables. To tackle this problem, we efficiently check the feasibility of the formulated problem by utilizing graph theory and topology theory. Next, we prove that the optimal UAV trajectory need to satisfy the \\\\emph{fly-hover-fly} structure. With this insight, we first design an efficient solution with predefined hovering locations by leveraging graph theory techniques. Furthermore, we propose an iterative UAV trajectory design by applying successive convex approximation (SCA) technique, which is guaranteed to coverage to a locally optimal solution. We demonstrate that the two proposed designs exhibit polynomial time complexity. Finally, numerical results show that: 1) the SCA based design outperforms the fly-hover-fly based design; 2) the UAV mission completion time is significantly minimized with proposed NOMA schemes compared with the orthogonal multiple access (OMA) scheme; 3) the increase of GUEs' QoS requirements will increase the UAV mission completion time.\",\n \"Title: The Application Of Multi-Agent Reinforcement Learning In Uav Networks\\nYear: 2019\\n\\nAbstract: This article investigates autonomous resource allocation of multiple UAVs enabled communication networks with the goal of maximizing long-term rewards. To model the uncertainty of environments, we formulate the long-term resource allocation problem as a stochastic game, where each UAV becomes a learning agent and each resource allocation solution corresponds to an action taken by the UAVs. Furthermore, we propose a multi-agent reinforcement learning (MARL) framework that. each agent discovers its best strategy according to its local observations using learning. More specifically, we propose an agent-independent method, for which all agents conduct a decision algorithm independently but share a common structure based on Q-learning. Finally, simulation results reveal that the proposed MARL algorithm provides acceptable performance compared to the case with complete information exchanges among UAVs.\",\n \"Title: Modeling and Coverage Analysis of Downlink UAV Networks with MmWave Communications\\nYear: 2019\\n\\nAbstract: In order to satisfy the requirement of high throughput in most unmanned aerial vehicle (UAV) applications, the potential of integrating millimeter wave (mmWave) communications into UAV networks is explored in this paper. A tractable three-dimensional (3D) spatial model is proposed for evaluating the average downlink performance of UAV networks at mmWave bands, where the locations of UAVs and users are randomly distributed with the aid of a Poisson cluster process. Moreover, a typical 3D antenna model with the uniform planar array is deployed at all UAVs to examine the impact of both azimuth and elevation angles. Based on this framework and an ordered user selection scheme, closed-form approximation equations of coverage probabilities are derived. In a noise-limited scenario, an exact expression is provided, which theoretically demonstrates that the coverage performance can be enhanced by increasing the number of antenna elements. Regarding the altitude of UAVs, there exists an optimal height for maximizing the evaluated coverage probability. Numerical results illustrate that non-line-of-sight transmissions caused by obstacles have negligible effects on the considered system.\",\n \"Title: Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G\\nYear: 2022\\n\\nAbstract: Due to the explosive growth in the number of wireless devices and diverse wireless services, such as virtual/augmented reality and Internet-of-Everything, next generation wireless networks face unprecedented challenges caused by heterogeneous data traffic, massive connectivity, and ultra-high bandwidth efficiency and ultra-low latency requirements. To address these challenges, advanced multiple access schemes are expected to be developed, namely next generation multiple access (NGMA), which are capable of supporting massive numbers of users in a more resource- and complexity-efficient manner than existing multiple access schemes. As the research on NGMA is in a very early stage, in this paper, we explore the evolution of NGMA with a particular focus on non-orthogonal multiple access (NOMA), i.e., the transition from NOMA to NGMA. In particular, we first review the fundamental capacity limits of NOMA, elaborate on the new requirements for NGMA, and discuss several possible candidate techniques. Moreover, given the high compatibility and flexibility of NOMA, we provide an overview of current research efforts on multi-antenna techniques for NOMA, promising future application scenarios of NOMA, and the interplay between NOMA and other emerging physical layer techniques. Furthermore, we discuss advanced mathematical tools for facilitating the design of NOMA communication systems, including conventional optimization approaches and new machine learning techniques. Next, we propose a unified framework for NGMA based on multiple antennas and NOMA, where both downlink and uplink transmissions are considered, thus setting the foundation for this emerging research area. Finally, several practical implementation challenges for NGMA are highlighted as motivation for future work.\",\n \"Title: Transmit Power Pool Design for Uplink IoT Networks with Grant-free NOMA\\nYear: 2021\\n\\nAbstract: Grant-free non-orthogonal multiple access (GFNOMA) is a potential multiple access framework for internet-of-things (IoT) networks to enhance connectivity. However, the resource allocation problem in GF-NOMA is challenging and the effectiveness of such a solution is limited due to the absence of closed-loop power control. In this paper, we design a prototype of layer-based transmit power pool by utilizing multi-agent reinforcement learning to provide open-loop power control and offload the computing tasks at the base station (BS) side. IoT users in each layer decide their own transmit power level from this layer-based power pool, instead of transmitting on the allocated sub-channel with allocated transmit power level. The proposed algorithm does not require any information exchange between IoT users and does not rely on any assistance from the BS. Numerical results confirm that the double deep Q network based GF-NOMA algorithm achieves high accuracy and finds out an accurate transmit power level for each layer. Moreover, the proposed GF-NOMA system outperforms the traditional GF with orthogonal multiple access techniques in terms of throughput.\",\n \"Title: Capacity Characterization of Intelligent Reflecting Surface Assisted NOMA Systems\\nYear: 2021\\n\\nAbstract: This paper investigates intelligent reflecting surface (IRS)-assisted systems, where an access point sends independent information to multiple users with the aid of one IRS. Our goal is to characterize the capacity region of the IRS-assisted multiuser communication systems. We jointly optimize the discrete phase-shift matrix of the IRS and resource allocation with the capacity-achieving non-orthogonal multiple access (NOMA) transmission scheme. The Pareto boundary of the capacity region is characterized by maximizing the average sum rate of all users, subject to a set of rate-profile constraints, total transmit power and discrete IRS phase shift constraints. Though the formulated problem is non-convex, we derive the globally optimal solutions by invoking the Lagrange duality method. It is shown that the optimal transmission strategy is alternating transmission among different user groups by dynamically adjusting the IRS phase shifts. We further propose a Hadamard codebook based scheme, which serves as a lower bound on the optimal performance gains. Numerical results demonstrate that: i) the IRS is capable of significantly improving the capacity region; ii) the capacity region achieved by the Hadamard codebook based scheme is close to that of discrete phase shifts for a small number of IRS elements.\",\n \"Title: STAR-RIS Aided NOMA in Multicell Networks: A General Analytical Framework With Gamma Distributed Channel Modeling\\nYear: 2022\\n\\nAbstract: The simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is capable of providing full-space coverage of smart radio environments. This work investigates STAR-RIS aided downlink non-orthogonal multiple access (NOMA) multi-cell networks, where the energy of incident signals at STAR-RISs is split into two portions for transmitting and reflecting. We first propose a fitting method to model the distribution of composite small-scale fading power as the tractable Gamma distribution. Then, a unified analytical framework based on stochastic geometry is provided to capture the random locations of RIS-RISs, base stations (BSs), and user equipments (UEs). Based on this framework, we derive the coverage probability and ergodic rate of both the typical UE and the connected UE. In particular, we obtain closed-form expressions of the coverage probability in interference-limited scenarios. We also deduce theoretical expressions in conventional RIS aided networks for comparison. The analytical results show that optimal energy splitting coefficients of STAR-RISs exist to simultaneously maximize the system coverage and ergodic rate. The numerical results demonstrate that: 1) STAR-RISs are able to meet different demands of UEs located on different sides; 2) STAR-RISs with appropriate energy splitting coefficients outperform conventional RISs in the coverage and the rate performance.\",\n \"Title: Trajectory Optimization for UAV Emergency Communication With Limited User Equipment Energy: A Safe-DQN Approach\\nYear: 2021\\n\\nAbstract: In post-disaster scenarios, it is challenging to provide reliable and flexible emergency communications, especially when the mobile infrastructure is seriously damaged. This article investigates the unmanned aerial vehicle (UAV)-based emergency communication networks, in which UAV is used as a mobile aerial base station for collecting information from ground users in affected areas. Due to the bre...\",\n \"Title: STAR-RIS Integrated Nonorthogonal Multiple Access and Over-the-Air Federated Learning: Framework, Analysis, and Optimization\\nYear: 2022\\n\\nAbstract: This article integrates nonorthogonal multiple access (NOMA) and over-the-air federated learning (AirFL) into a unified framework using one simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS). The STAR-RIS plays an important role in adjusting the decoding order of hybrid users for efficient interference mitigation and omnidirectional coverage extension. To capture the impact of nonideal wireless channels on AirFL, a closed-form expression for the optimality gap (also known as the convergence upper bound) between the actual loss and the optimal loss is derived. This analysis reveals that the learning performance is significantly affected by the active and passive beamforming schemes, as well as wireless noise. Furthermore, when the learning rate diminishes as the training proceeds, the optimality gap is explicitly shown to converge with a linear rate. To accelerate convergence while satisfying quality-of-service requirements, a mixed-integer nonlinear programming (MINLP) problem is formulated by jointly designing the transmit power at users and the configuration mode of STAR-RIS. Next, a trust-region-based successive convex approximation method and a penalty-based semidefinite relaxation approach are proposed to handle the decoupled nonconvex subproblems iteratively. An alternating optimization algorithm is then developed to find a suboptimal solution for the original MINLP problem. Extensive simulation results show that: 1) the proposed framework can efficiently support NOMA and AirFL users via concurrent uplink communications; 2) our algorithms achieve a faster convergence rate on independent and identically distributed (IID) and non-IID settings compared to the existing baselines; and 3) both the spectrum efficiency and learning performance are significantly improved with the aid of the well-tuned STAR-RIS.\",\n \"Title: STAR-RISs: Simultaneous Transmitting and Reflecting Reconfigurable Intelligent Surfaces\\nYear: 2021\\n\\nAbstract: In this letter, simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) are studied. Compared with the conventional reflecting-only RISs, the coverage of STAR-RISs is extended to 360 degrees via simultaneous transmission and reflection. A general hardware model for STAR-RISs is presented. Then, channel models are proposed for the near-field and the far-field scenar...\",\n \"Title: STAR-IOS Aided NOMA Networks: Channel Model Approximation and Performance Analysis\\nYear: 2022\\n\\nAbstract: Compared with the conventional reconfigurable intelligent surfaces (RIS), simultaneous transmitting and reflecting intelligent omini-surfaces (STAR-IOSs) are able to achieve 360° coverage “smart radio environments”. By splitting the energy or altering the active number of STAR-IOS elements, STAR-IOSs provide high flexibility of successive interference cancellation (SIC) orders for non-orthogonal multiple access (NOMA) systems. Based on the aforementioned advantages, this paper investigates a STAR-IOS-aided downlink NOMA network with randomly deployed users. We first propose three tractable channel models for different application scenarios, namely the central limit model, the curve fitting model, and the M-fold convolution model. More specifically, the central limit model fits the scenarios with large-size STAR-IOSs while the curve fitting model is extended to evaluate multi-cell networks. However, these two models cannot obtain accurate diversity orders. Hence, we figure out the M-fold convolution model to derive accurate diversity orders. We consider three protocols for STAR-IOSs, namely, the energy splitting (ES) protocol, the time switching (TS) protocol, and the mode switching (MS) protocol. Based on the ES protocol, we derive closed-form analytical expressions of outage probabilities for the paired NOMA users by the central limit model and the curve fitting model. Based on three STAR-IOS protocols, we derive the diversity gains of NOMA users by the M-fold convolution model. The analytical results reveal that the diversity gain of NOMA users is equal to the active number of STAR-IOS elements. Numerical results indicate that 1) in high signal-to-noise ratio regions, the central limit model performs as an upper bound of the simulation results, while a lower bound is obtained by the curve fitting model; 2) the TS protocol has the best performance but requesting more time blocks than other protocols; 3) the ES protocol outperforms the MS protocol as the ES protocol has higher diversity gains.\",\n \"Title: Graph-Embedded Multi-Agent Learning for Smart Reconfigurable THz MIMO-NOMA Networks\\nYear: 2022\\n\\nAbstract: With the accelerated development of immersive applications and the explosive increment of internet-of-things (IoT) terminals, 6G would introduce terahertz (THz) massive multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) technologies to meet the ultra-high-speed data rate and massive connectivity requirements. Nevertheless, the unreliability of THz transmissions and the extre...\",\n \"Title: Energy-Constrained UAV Data Collection Systems: NOMA and OMA\\nYear: 2021\\n\\nAbstract: This paper investigates unmanned aerial vehicle (UAV) data collection systems with different multiple access schemes, where a rotary-wing UAV is dispatched to collect data from multiple ground nodes (GNs). Our goal is to maximize the minimum UAV data collection throughput from GNs for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) transmission, subject to the energ...\",\n \"Title: Over-the-Air Federated Learning and Non-Orthogonal Multiple Access Unified by Reconfigurable Intelligent Surface\\nYear: 2021\\n\\nAbstract: With the aim of integrating over-the-air federated learning (AirFL) and non-orthogonal multiple access (NOMA) into an on-demand universal framework, this paper proposes a novel reconfigurable intelligent surface (RIS)-unified network by leveraging the RIS to flexibly adjust the signal processing order of hybrid users. The objective of this work is to maximize the achievable hybrid rate of all users by jointly optimizing the transmit power at users, controlling the receive scalar at the base station, and designing the phase shifts at the RIS. Due to the fact that all signals of computation and communication are combined into one concurrent transmission, the formulated resource allocation problem is very challenging. To solve this problem, the alternating optimization is invoked to address non-convex subproblems iteratively for finding a suboptimal solution with low complexity. Simulation results demonstrate that i) the proposed RIS-unified network can support the on-demand communication and computation efficiently, and ii) the designed algorithms are also applicable to conventional networks with only AirFL or NOMA users.\",\n \"Title: Adaptive Reinforcement Learning Framework for NOMA-UAV Networks\\nYear: 2021\\n\\nAbstract: We propose an adaptive reinforcement learning (A-RL) framework to maximize the sum-rate for non-orthogonal multiple access-unmanned aerial vehicle (NOMA-UAV) network. In this framework, Mamdani fuzzy inference system (MFIS) supervises a reinforcement learning (RL) policy based on multi-armed bandits (MAB). UAV as learning agent serves an internet of things (IoT) region. It manages an interference ...\",\n \"Title: Simultaneously Transmitting and Reflecting (STAR)-RISs: A Coupled Phase-Shift Model\\nYear: 2022\\n\\nAbstract: A simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided communication system is investigated, where an access point sends information to two users located on each side of the STAR-RIS. Different from current works assuming that the phase-shift coefficients for transmission and reflection can be independently adjusted, which is non-trivial to realize for purely passive STAR-RISs, a coupled transmission and reflection phase-shift model is considered. Based on this model, a power consumption minimization problem is formulated for both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA). In particular, the amplitude and phase-shift coefficients for transmission and reflection are jointly optimized, subject to the rate constraints of the users. To solve this non-convex problem, an efficient element-wise alternating optimization algorithm is developed to find a high-quality suboptimal solution, whose complexity scales only linearly with the number of STAR elements. Finally, numerical results are provided for both NOMA and OMA to validate the effectiveness of the proposed algorithm by comparing its performance with that of STAR-RISs using the independent phase-shift model and conventional reflecting/transmitting-only RISs.\",\n \"Title: NOMA-Aided Joint Radar and Multicast-Unicast Communication Systems\\nYear: 2022\\n\\nAbstract: The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric users (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">double spectrum sharing</i>\\n, where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. First, a \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">beamformer-based</i>\\n NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Next, the system is extended to the scenario of multiple pairs of R- and C-users, where a \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">cluster-based</i>\\n NOMA-aided joint Rad-MU-Com framework is proposed. A joint beamformer design and power allocation optimization problem is formulated for the maximization of the sum of the unicast rate at each C-user, subject to the constraints on both the minimum multicast rate for each R&C pair and on accuracy of the radar beam pattern for detecting multiple R-users. The resultant joint optimization problem is efficiently solved by another penalty-based iterative algorithm developed. Finally, our numerical results reveal that significant performance gains can be achieved by the proposed schemes over the benchmark schemes employing conventional transmission strategies.\",\n \"Title: Meta-learning for RIS-assisted NOMA Networks\\nYear: 2021\\n\\nAbstract: A novel reconfigurable intelligent surfaces (RISs)-based transmission framework is proposed for downlink non-orthogonal multiple access (NOMA) networks. We propose a quality-of-service (QoS)-based clustering scheme to improve the resource efficiency and formulate a sum rate maximization problem by jointly optimizing the phase shift of the RIS and the power allocation at the base station (BS). A model-agnostic meta-learning (MAML)-based learning algorithm is proposed to solve the joint optimization problem with a fast convergence rate and low model complexity. Extensive simulation results demonstrate that the proposed QoS-based NOMA network achieves significantly higher transmission throughput compared to the conventional orthogonal multiple access (OMA) network. It can also be observed that substantial throughput gain can be achieved by integrating RISs in NOMA and OMA networks. Moreover, simulation results of the proposed QoS-based clustering method demonstrate observable throughput gain against the conventional channel condition-based schemes.\",\n \"Title: Resource Allocation in STAR-RIS-Aided Networks: OMA and NOMA\\nYear: 2022\\n\\nAbstract: Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is a promising technology that aids in achieving full-space coverage on both sides of the surface, by splitting the incident signal into transmitted and reflected signals. This paper investigates the resource allocation problem in a STAR-RIS-assisted multi-carrier communication networks. To maximize the system sum-rate, a joint optimization problem comprising of the channel assignment, power allocation, and transmission and reflection beamforming at the STAR-RIS for orthogonal multiple access (OMA) is first formulated. To solve this challenging problem, we first propose a channel assignment scheme utilizing matching theory and then invoke the alternating optimization-based method to optimize the resource allocation policy and beamforming vectors iteratively. Furthermore, the sum-rate maximization problem for non-orthogonal multiple access (NOMA) with flexible decoding orders is investigated. To efficiently solve it, we first propose a location-based matching algorithm to determine the sub-channel assignment, where a transmitted user and a reflected user are grouped on a sub-channel. Based on this \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">transmission-and-reflection</i>\\n sub-channel assignment strategy, a three-step approach is proposed, which involves the optimization of decoding orders, beamforming-coefficient vectors, and power allocation, by employing semidefinite programming, convex upper bound approximation, and geometry programming, respectively. Numerical results unveil that: 1) For OMA, a general design that includes the same-side user-pairing for channel assignment is preferable, whereas for NOMA, the proposed transmission-and-reflection scheme can achieve comparable performance to the exhaustive search-based algorithm. 2) The STAR-RIS-aided NOMA network significantly outperforms networks employing conventional RISs and OMA.\",\n \"Title: A Novel Design of RIS for Enhancing the Physical Layer Security for RIS-Aided NOMA Networks\\nYear: 2021\\n\\nAbstract: This letter proposes a novel design of reconfigurable intelligent surface (RIS) to enhance the physical layer security (PLS) in the RIS-aided non-orthogonal multiple access (NOMA) network. Under the design of the RIS, the problem of increasing the number of RIS elements damaging the secrecy performance is solved. Besides, it also ensures that the networks can use traditional channel coding schemes...\",\n \"Title: AI-Driven UAV-NOMA-MEC in Next Generation Wireless Networks\\nYear: 2021\\n\\nAbstract: Driven by the unprecedented high throughput and low latency requirements anticipated for next generation wireless networks, this article introduces an artificial intelligence (AI)-enabled framework in which unmanned aerial vehicles use non-orthogonal multiple access and mobile edge computing techniques to serve terrestrial mobile users (MUs). The proposed framework enables terrestrial MUs to offlo...\",\n \"Title: User Grouping and Energy Harvesting in UAV-NOMA System With AF/DF Relaying\\nYear: 2021\\n\\nAbstract: The development of unmanned aerial vehicles (UAVs) is one of the driving forces for revolutionizing wireless communications in the modern era. Although there are many unique features of UAV networks, their widespread use is still hampered by the short battery life. As a result, most of the research efforts in this domain mainly have focused on the efficient use of energy through trajectory plannin...\",\n \"Title: STAR-RISs: A Correlated T&R Phase-Shift Model and Practical Phase-Shift Configuration Strategies\\nYear: 2022\\n\\nAbstract: A \\n<italic xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">correlated</i>\\n transmission and reflection (T&R) phase-shift model is proposed for passive lossless simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs). A STAR-RIS-aided two-user downlink communication system is investigated for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA). To evaluate the impact of the correlated T&R phase-shift model on the communication performance, three phase-shift configuration strategies are developed, namely the primary-secondary phase-shift configuration (PS-PSC), the diversity preserving phase-shift configuration (DP-PSC), and the T/R-group phase-shift configuration (TR-PSC) strategies. Furthermore, we derive the outage probabilities for the three proposed phase-shift configuration strategies as well as for those for the random phase-shift configuration and the independent phase-shift model, which constitute performance lower and upper bounds, respectively. Then, the diversity order of each strategy is investigated based on the obtained analytical results. It is shown that the proposed DP-PSC strategy achieves full diversity order simultaneously for users located on both sides of the STAR-RIS. Moreover, power scaling laws are derived for the three proposed strategies and for the random phase-shift configuration. Numerical simulations reveal a performance gain if the users on both sides of the STAR-RIS are served by NOMA instead of OMA. Moreover, it is shown that the proposed DP-PSC strategy yields the same diversity order as achieved by STAR-RISs under the independent phase-shift model and a comparable power scaling law with only 4 dB reduction in received power.\",\n \"Title: A New Look at AI-Driven NOMA-F-RANs: Features Extraction, Cooperative Caching, and Cache-Aided Computing\\nYear: 2022\\n\\nAbstract: Non-orthogonal multiple access-enabled fog radio access networks (NOMA-F-RANs) are thought of as a promising enabler to release network congestion, reduce delivery latency, and improve fog user equipment (F-UEs) quality of service. Never-theless, the effectiveness of NOMA-F-RANs highly relies on the charted feature information (e.g., preference distribution, positions, and mobilities) of F-UEs as well as the effective caching, computing, and resource allocation strategies. In this article, we explore how artificial intelligence (AI) techniques are utilized to solve foregoing challenges. Specifically, we first elaborate on the NOMA-F-RANs architecture, shedding light on the key modules, namely, cooperative caching and cache-aided mobile edge computing. Then, the potentially applicable AI-driven techniques in solving the principal issues of NOMA-F-RANs are reviewed. Through case studies, we show the efficacy of AI-enabled methods in terms of the latent feature extraction and cooperative caching of F-UEs. Finally, future trends of AI-driven NOMA-F-RANs, including open research issues and challenges, are identified.\",\n \"Title: Channel Estimation for STAR-RIS-Aided Wireless Communication\\nYear: 2022\\n\\nAbstract: In this letter, we study efficient uplink channel estimation design for a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted two-user communication systems. We first consider the time switching (TS) protocol for STAR-RIS and propose an efficient scheme to separately estimate the channels of the two users with optimized training (transmission/reflectio...\",\n \"Title: NOMA Empowered Integrated Sensing and Communication\\nYear: 2022\\n\\nAbstract: A non-orthogonal multiple access (NOMA) empowered integrated sensing and communication (ISAC) framework is investigated. A dual-functional base station serves multiple communication users employing NOMA, while the superimposed NOMA communication signal is simultaneously exploited for target sensing. A beamforming design problem is formulated to maximize the weighted sum of the communication throug...\",\n \"Title: AI Empowered RIS-Assisted NOMA Networks: Deep Learning or Reinforcement Learning?\\nYear: 2022\\n\\nAbstract: A reconfigurable intelligent surface (RIS)-assisted multi-user downlink communication system over fading channels is investigated, where both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) schemes are employed. In particular, the time overhead for configuring the RIS reflective elements at the beginning of each fading channel is considered. The optimization goal is maxi...\",\n \"Title: NOMA Inspired Interference Cancellation for Integrated Sensing and Communication\\nYear: 2022\\n\\nAbstract: A non-orthogonal multiple access (NOMA) inspired integrated sensing and communication (ISAC) system is investigated. A dual-functional base station (BS) serves multiple communication users while sensing multiple targets, by transmitting the non-orthogonal superposition of the communication and sensing signals. A NOMA inspired interference cancellation scheme is proposed, where part of the dedicated sensing signal is treated as the virtual communication signals to be mitigated at each communication user via successive interference cancellation (SIC). Based on this framework, the transmitted communication and sensing signals are jointly optimized to match the desired sensing beampattern, while satisfying the minimum rate requirement and the SIC condition at the communication users. Then, the formulated non-convex optimization problem is solved by invoking the successive convex approximation (SCA) to obtain a near-optimal solution. The numerical results show the proposed NOMA-inspired ISAC system can achieve better performance than the conventional ISAC system and comparable performance to the ideal ISAC system where all sensing interference is assumed to be removed unconditionally.\",\n \"Title: On the Performance of Uplink ISAC Systems\\nYear: 2022\\n\\nAbstract: This letter analyzes the performance of uplink integrated sensing and communications (ISAC) systems where communication users (CUs) and radar targets (RTs) share the same frequency band. A non-orthogonal multiple access (NOMA) protocol is adopted in the communication procedure of the ISAC system. Novel expressions are derived to characterize the outage probability, ergodic communication rate, and sensing rate. Besides, the diversity order and high signal-to-noise ratio (SNR) slope are unveiled to gain further insights. It is found that when achieving the same communication rate, the ISAC system enjoys a higher sensing rate than the conventional frequency-division sensing and communications (FDSAC) system where CUs and RTs share isolated bands. All the results are validated by numerical simulations and are in excellent agreement.\",\n \"Title: Deep Learning for Latent Events Forecasting in Content Caching Networks\\nYear: 2022\\n\\nAbstract: A novel Twitter context aided content caching (TAC) framework is proposed for enhancing the caching efficiency by taking advantage of the legibility and massive volume of Twitter data. For the purpose of promoting the caching efficiency, three machine learning models are proposed to predict latent events and events popularity, utilizing collected Twitter data with geo-tags and geographic informati...\",\n \"Title: A Reliable Reinforcement Learning for Resource Allocation in Uplink NOMA-URLLC Networks\\nYear: 2022\\n\\nAbstract: In this paper, we propose a deep state-action-reward-state-action (SARSA) \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$\\\\lambda $ </tex-math></inline-formula>\\n learning approach for optimising the uplink resource allocation in non-orthogonal multiple access (NOMA) aided ultra-reliable low-latency communication (URLLC). To reduce the mean decoding error probability in time-varying network environments, this work designs a reliable learning algorithm for providing a long-term resource allocation, where the reward feedback is based on the instantaneous network performance. With the aid of the proposed algorithm, this paper addresses three main challenges of the reliable resource sharing in NOMA-URLLC networks: 1) user clustering; 2) Instantaneous feedback system; and 3) Optimal resource allocation. All of these designs interact with the considered communication environment. Lastly, we compare the performance of the proposed algorithm with conventional Q-learning and SARSA Q-learning algorithms. The simulation outcomes show that: 1) Compared with the traditional Q learning algorithms, the proposed solution is able to converge within 200 episodes for providing as low as \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$10^{-2}$ </tex-math></inline-formula>\\n long-term mean error; 2) NOMA assisted URLLC outperforms traditional OMA systems in terms of decoding error probabilities; and 3) The proposed feedback system is efficient for the long-term learning process.\",\n \"Title: MIMO Assisted Networks Relying on Intelligent Reflective Surfaces: A Stochastic Geometry Based Analysis\\nYear: 2022\\n\\nAbstract: Intelligent reflective surfaces (IRSs) are invoked for improving both the spectral efficiency (SE) and energy efficiency (EE). Specifically, an IRS-aided multiple-input multiple-output network is considered, where the performance of randomly roaming users is analyzed by utilizing stochastic geometry tools. As such, to distinguish the superposed signals at each user, the passive beamforming weight ...\",\n \"Title: Joint Trajectory and Resource Optimization for UAV-Aided Two-Way Relay Networks\\nYear: 2022\\n\\nAbstract: Unmanned aerial vehicle (UAV)-aided two-way relay networks with multiple terrestrial user pairs is investigated, where a fix-wing UAV is served as a two-way relay to assist information transmission. We aim to maximize the total rate of the two-way relay networks while the quality of service (QoS) being guaranteed. A novel relay strategy, namely time-slots pairing, is proposed by e...\",\n \"Title: STAR: Simultaneous Transmission and Reflection for 360° Coverage by Intelligent Surfaces\\nYear: 2021\\n\\nAbstract: A novel simultaneous transmitting and reflecting (STAR) system design relying on reconfigurable intelligent surfaces (RISs) is conceived. First, an existing prototype is reviewed, and the potential benefits of STAR-RISs are discussed. Then the key differences between conventional reflecting-only RISs and STAR-RISs are identified from the perspectives of hardware design, physical principles, and co...\",\n \"Title: Reliable Reinforcement Learning Based NOMA Schemes for URLLC\\nYear: 2021\\n\\nAbstract: In this paper, we propose a deep state-action-reward-state-action (SARSA) \\n<tex xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\">$A$</tex>\\n learning approach for optimising the uplink resource allocation in non-orthogonal multiple access (NOMA) aided ultra-reliable low-latency communication (URLLC). To reduce the mean decoding error probability in time-varying network environments, this work designs a reliable learning algorithm for providing a long-term resource allocation, where the reward feedback is based on the instantaneous network performance. With the aid of the proposed algorithm, this paper addresses three main challenges of the reliable resource sharing in NOMA-URLLC networks: 1) Dynamic user clustering; 2) Instantaneous feedback system; and 3) Optimal resource allocation. All of these designs interact with the considered communication environment. The simulation outcomes show that: 1) Compared with the traditional Q learning algorithm, the proposed solution converges faster and obtains better performance; 2) NOMA assisted URLLC outperforms traditional OMA systems in terms of decoding error probabilities; and 3) The dynamic feedback system is efficient for the long-term learning process.\",\n \"Title: Enabling Ubiquitous Non-Orthogonal Multiple Access and Pervasive Federated Learning via STAR-RIS\\nYear: 2021\\n\\nAbstract: This paper proposes a new, compatible, unified framework which integrates non-orthogonal multiple access (NOMA) and over-the-air federated learning (AirFL) via concurrent communication. In particular, a simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is leveraged to adjust the signal processing order for efficient interference mitigation and omni-directional coverage extension. With the aim of investigating the impact of non-ideal wireless communication on AirFL, we provide a closed-form expression for the optimality gap over a given number of communication rounds. This result reveals that the learning performance is significantly affected by the resource allocation scheme and channel noise. To minimize the derived optimality gap, a mixed-integer non-linear programming (MINLP) problem is formulated by jointly designing the transmit power at users and configuration mode at the STAR-RIS. Through developing an alternating optimization algorithm, a suboptimal solution for the original MINLP problem is obtained. Simulation results show that the learning performance in terms of training loss and test accuracy can be effectively improved with the aid of the STAR-RIS.\",\n \"Title: Enhancing Security of NOMA Networks via Distributed Intelligent Reflecting Surfaces\\nYear: 2021\\n\\nAbstract: This paper investigates the security enhancement of an intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) network, where a distributed IRS enabled NOMA transmission framework is proposed to serve users securely in the presence of a passive eavesdropper. Considering that the instantaneous channel state information (CSI) of the eavesdropper is challenging to acquire in practice, we utilize the secrecy outage probability (SOP) as the security metric. A problem by jointly optimizing the transmit power at the base station (BS) and reflection phase shifts at IRSs, subject to the successive interference cancellation (SIC) decoding constraints and SOP constraints, is formulated to maximize the minimum secrecy rate among legitimate users. To tackle the non-convex problem, we first derive the exact SOP in closed-form expressions and then propose a novel ring-penalty based successive convex approximation (SCA) algorithm to design power allocation and phase shifts jointly. Numerical results validate the convergence and the secrecy superiority of proposed scheme over the baseline schemes.\",\n \"Title: Simultaneously Transmitting And Reflecting RIS Aided NOMA With Randomly Deployed Users\\nYear: 2021\\n\\nAbstract: To achieve 360 degrees coverage, we investigate a simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) aided downlink non-orthogonal multiple access (NOMA) network with randomly deployed users. For different scenarios, we first derive two STAR-RIS-aided channel models, namely the central limit model and the curve fitting model. More specifically, the central limit model fits the scenarios with numerous RIS elements while the curve fitting model can be extended to multi-cell scenarios. The analytical results reveal that 1) the central limit model has closed-form expressions calculated as the error functions, and 2) the curve fitting model can be closely modeled as a Gamma distribution. We then derive the closed-form outage probability expressions for the NOMA users. Numerical results indicate that 1) the two channel models match the simulation results well in low signal-to-noise-ratio (SNR) regions and perform as boundaries in high SNR regions, 2) the central limit model performs as an upper bound of the simulation results, while a lower bound can be obtained by the curve fitting model, and 3) the both users in the NOMA pair have no error floor.\",\n \"Title: Simultaneously Transmitting And Reflecting (STAR) RIS Assisted NOMA Systems\\nYear: 2021\\n\\nAbstract: In this paper, a novel simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted non-orthogonal multiple access (NOMA) system is proposed, where the STAR-RIS can simultaneously transmit and reflect the incident signals. Our objective is to maximize the achievable sum rate by jointly optimizing the decoding order, power allocation coefficients, active beamforming, transmission and reflection beamformings. However, the formulated problem is non-convex with intricately coupled variables. To tackle this challenge, a suboptimal two-layer iterative algorithm is proposed. Specifically, in the inner-layer iteration, for a given decoding order, the power allocation coefficients, active beamforming, transmission and reflection beamformings are optimized alternatively. For the outer-layer iteration, the decoding order of NOMA users in each cluster is updated with the solutions obtained from the inner-layer iteration. Simulation results are provided to demonstrate that the proposed STAR-RSI-NOMA system outperforms conventional RIS assisted systems.\",\n \"Title: Semi-Integrated-Sensing-and-Communication (Semi-ISaC) Networks Assisted by NOMA\\nYear: 2022\\n\\nAbstract: This paper investigates non-orthogonal multiple access (NOMA) assisted integrated sensing and communication (ISaC) networks. Compared to the conventional ISaC networks, where the total bandwidth is used for both the radar detection and wireless communications, the proposed Semi-ISaC networks allow that a portion of bandwidth is used for ISaC and the rest of the bandwidth is only utilized for wireless communications. We first derive the analytical expressions of the outage probability for the communication signals, including the signals for the radar target and the communication transmitter. Additionally, we derive the analytical expressions of the ergodic radar estimation information rate (REIR) for the radar echoes. The simulation results show that 1) NOMA ISaC has better spectrum efficiency than the conventional ISaC; and 2) The REIR is enhanced when we enlarge the density of pulses.\",\n \"Title: Energy Efficient Resource Allocation for MSCA Enabled CoMP in HetNets\\nYear: 2022\\n\\nAbstract: A novel multi-stream carrier aggregation (MSCA) enabled coordinated multi-point (CoMP) framework in heterogeneous cellular networks (HetNets) is proposed. Our objective is to maximize the energy efficiency (EE) of the proposed framework by jointly optimizing base station (BS) clustering, user association, sub-carrier assignment and power allocation. The formulated problem is proved to be NP-hard. ...\",\n \"Title: Joint Radar and Multicast-Unicast Communication: A NOMA Aided Framework\\nYear: 2022\\n\\nAbstract: The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric user (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this double spectrum sharing, where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. A beamformer-based NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Finally, our numerical results reveal that significant performance gains can be achieved by the proposed scheme over the benchmark schemes.\",\n \"Title: Learning Non-target Knowledge for Few-shot Semantic Segmentation\\nYear: 2022\\n\\nAbstract: Existing studies in few-shot semantic segmentation only focus on mining the target object information, however, often are hard to tell ambiguous regions, especially in non-target regions, which include background (BG) and Distracting Objects (DOs). To alleviate this problem, we propose a novel framework, namely Non-Target Region Eliminating (NTRE) network, to explicitly mine and eliminate BG and DO regions in the query. First, a BG Mining Module (BGMM) is proposed to extract the BG region via learning a general BG prototype. To this end, we design a BG loss to supervise the learning of BGMM only using the known target object segmentation ground truth. Then, a BG Eliminating Module and a DO Eliminating Module are proposed to successively filter out the BG and DO information from the query feature, based on which we can obtain a BG and DO-free target object segmentation result. Furthermore, we propose a prototypical contrastive learning algorithm to improve the model ability of distinguishing the target object from DOs. Extensive experiments on both PASCAL-5 i and COCO-20 i datasets show that our approach is effective despite its simplicity. Code is available at https://github.com/LIUYUANWEI98/NERTNet\",\n \"Title: Hybrid Reinforcement Learning for STAR-RISs: A Coupled Phase-Shift Model Based Beamformer\\nYear: 2022\\n\\nAbstract: A simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted multi-user downlink multiple-input single-output (MISO) communication system is investigated. In contrast to the existing ideal STAR-RIS model assuming an independent transmission and reflection phase-shift control, a practical coupled phase-shift model is considered. Then, a joint active and passive beamforming optimization problem is formulated for minimizing the long-term transmission power consumption, subject to the coupled phase-shift constraint and the minimum data rate constraint. Despite the coupled nature of the phase-shift model, the formulated problem is solved by invoking a hybrid continuous and discrete phase-shift control policy. Inspired by this observation, a pair of hybrid reinforcement learning (RL) algorithms, namely the hybrid deep deterministic policy gradient (hybrid DDPG) algorithm and the joint DDPG & deep-Q network (DDPG-DQN) based algorithm are proposed. The hybrid DDPG algorithm controls the associated high-dimensional continuous and discrete actions by relying on the hybrid action mapping. By contrast, the joint DDPG-DQN algorithm constructs two Markov decision processes (MDPs) relying on an inner and an outer environment, thereby amalgamating the two agents to accomplish a joint hybrid control. Simulation results demonstrate that the STAR-RIS has superiority over other conventional RISs in terms of its energy consumption. Furthermore, both the proposed algorithms outperform the baseline DDPG algorithm, and the joint DDPG-DQN algorithm achieves a superior performance, albeit at an increased computational complexity.\",\n \"Title: Special Issue on Next Generation Multiple Access—Part I\\nYear: 2022\\n\\nAbstract: As the long-term evolution (LTE) system is reaching maturity and the fifth-generation (5G) systems are being commercially deployed, researchers have turned their attention to the development of next-generation wireless networks. Compared to current wireless networks, on the one hand, next-generation wireless networks are expected to achieve significantly higher capacity, extremely low latency, ult...\",\n \"Title: Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G\\nYear: 2022\\n\\nAbstract: Due to the explosive growth in the number of wireless devices and diverse wireless services, such as virtual/augmented reality and Internet-of-Everything, next generation wireless networks face unprecedented challenges caused by heterogeneous data traffic, massive connectivity, and ultra-high bandwidth efficiency and ultra-low latency requirements. To address these challenges, advanced multiple ac...\",\n \"Title: Two Time-Scale Caching Placement and User Association in Dynamic Cellular Networks\\nYear: 2022\\n\\nAbstract: With the rapid growth of data traffic in cellular networks, edge caching has become an emerging technology for traffic offloading. We investigate the caching placement and content delivery in cache-enabling cellular networks. To cope with the time-varying content popularity and user location in practical scenarios, we formulate a long-term joint dynamic optimization problem of caching placement an...\",\n \"Title: Blockage-Aware Beamforming Design for Active IRS-Aided mmWave Communication Systems\\nYear: 2022\\n\\nAbstract: In this paper, we investigate a robust beamforming design in a millimeter wave (mmWave) communication network with consideration of the random blockages. The network with multiple remote radio units (RRUs) is taken into account, where the joint transmission coordinated multi-point (JT-CoMP) scheme is adopted to improve the spectrum efficiency. To further enhance the communication performance and maintain the reliability of the network, an active intelligent reflecting surface (IRS) panel is deployed. We formulate the robust beamforming design of the mmWave communication network as an optimization problem aiming at minimizing the total transmit power at the RRUs subject to the average signal-to-interference-plus-noise ratio (SINR) constraints and power constraint over the active IRS. To deal with the challenge caused by the variables coupling, an algorithm based on the alternating optimization (AO) and semidefinite programming (SDP) is proposed. Numerical results illustrate that: i) the transmit power of the network can be reduced by deploying both the passive and active IRSs; ii) the integration of the active IRS and CoMP scheme can obtain a significant performance gain compared to that of the conventional passive IRS and CoMP.\",\n \"Title: Artificial Noise Aided Secure NOMA Communications in STAR-RIS Networks\\nYear: 2022\\n\\nAbstract: Combination of simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) and non-orthogonal multiple access (NOMA) is a win-win strategy which can significantly enhance the coverage performance. However, eavesdroppers may enjoy similar performance gains as the legitimate users. To solve this problem, an artificial noise (AN) assisted secure communication strategy is proposed to maximize the secrecy rate. An alternating optimization (AO) based iterative algorithm leveraging the classical successive convex approximation (SCA) and the semidefinite relaxation (SDR) techniques is proposed to derive the optimal AN model and the RIS parameters. It is found that the proposed algorithm provides better secrecy performance with less AN power compared with the benchmark schemes. More RIS elements help reducing the AN power, while this effect shrinks when the number of RIS elements is sufficiently large. Increasing the number of transmit antennas reduces the AN power if the eavesdropper is quite close to the transmitter, while improves it when the eavesdropper is far away.\",\n \"Title: Reconfigurable Intelligent Surface-Aided Multi-User Networks: Interplay Between NOMA and RIS\\nYear: 2022\\n\\nAbstract: This article focuses on the exploitation of reconfigurable intelligent surfaces (RISs) in multiuser networks employing orthogonal multiple access (OMA) or non-orthogonal multiple access (NOMA), with an emphasis on investigating the interplay between NOMA and RIS. Depending on whether the RIS reflection coefficients can be adjusted only once or multiple times during one transmission, we distinguish between static and dynamic RIS configurations. In particular, the capacity region of RIS-aided single-antenna NOMA networks is discussed and compared with the OMA rate region from an information-theoretic perspective, revealing that the dynamic RIS configuration is capacity-achieving. Then, the impact of the RIS deployment location on the performance of different multiple access schemes is investigated, which reveals that asymmetric and symmetric deployment strategies are preferable for NOMA and OMA, respectively. Furthermore, for RIS-aided multiple-antenna NOMA networks, three novel joint active and passive beamformer designs are proposed based on both beamformer-based and cluster-based strategies. Finally, open research problems for RIS-NOMA networks are highlighted.\",\n \"Title: Simultaneously Transmitting and Reflecting Intelligent Omni-Surfaces: Modeling and Implementation\\nYear: 2022\\n\\nAbstract: Given the rapid development of advanced electromagnetic (EM) manipulation technologies, researchers have turned their attention to the investigation of smart surfaces for enhancing radio coverage. Simultaneously transmitting and reflecting (STAR) intelligent omni-surfaces (IOSs) constitute one of the most promising categories. Although previous research contributions have demonstrated the benefits of simultaneously transmitting and reflecting intelligent omni-surfaces (STAR-IOSs) in terms of wireless communication performance gains, several important issues remain unresolved, including practical hardware implementations and accurate physical models. In this article, we address these by discussing four practical hardware implementations of STAR-IOSs as well as three hardware modeling techniques and five channel modeling methods. We thus clarify the taxonomy of smart surface technologies in support of further investigating the family of STAR-IOSs.\",\n \"Title: Federated Learning in Multi-RIS-Aided Systems\\nYear: 2022\\n\\nAbstract: The fundamental communication paradigms in the next-generation mobile networks are shifting from connected things to connected intelligence. The potential result is that current communication-centric wireless systems are greatly stressed when supporting computation-centric intelligent services with distributed big data. This is one reason that makes federated learning come into being, it allows collaborative training over many edge devices while avoiding the transmission of raw data. To tackle the problem of model aggregation in federated learning systems, this article resorts to multiple reconfigurable intelligent surfaces (RISs) to achieve efficient and reliable learning-oriented wireless connectivity. The seamless integration of communication and computation is actualized by over-the-air computation (AirComp), which can be deemed as one of the uplink nonorthogonal multiple access (NOMA) techniques without individual information decoding. Since all local parameters are uploaded via noisy concurrent transmissions, the unfavorable propagation error inevitably deteriorates the accuracy of the aggregated global model. The goals of this work are to 1) alleviate the signal distortion of AirComp over shared wireless channels and 2) speed up the convergence rate of federated learning. More specifically, both the mean-square error (MSE) and the device set in the model uploading process are optimized by jointly designing transceivers, tuning reflection coefficients, and selecting clients. Compared to baselines, extensive simulation results show that 1) the proposed algorithms can aggregate model more accurately and accelerate convergence and 2) the training loss and inference accuracy of federated learning can be improved significantly with the aid of multiple RISs.\",\n \"Title: Ergodic Rate Analysis of STAR-RIS Aided NOMA Systems\\nYear: 2022\\n\\nAbstract: This letter analyzes the ergodic rates of a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided non-orthogonal multiple access (NOMA) system, where the direct links from the base station to cell-edge users are non-line-of-sight due to obstacles, and STAR-RIS is used to provide line-of-sight links to these cell-edge users. By fitting the distribution of the composite channel power gain to a gamma distribution, we derive the closed-form expressions of ergodic rates and high signal-to-noise ratio (SNR) slopes for cell-edge users. Numerical results reveal that 1) the ergodic rates increase with the number of STAR-RIS elements, and the high SNR slopes are fixed as constants; 2) STAR-RIS aided NOMA systems achieve higher ergodic rates than conventional RIS aided NOMA systems.\",\n \"Title: Performance Analysis for the Coupled Phase-Shift STAR-RISs\\nYear: 2022\\n\\nAbstract: In this work, we focus on simultaneous transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) with coupled transmission and reflection phase shifts. We demonstrate how to achieve full diversity for users on both sides by proposing a practical phase-shift design, namely, the diversity preserving design. To evaluate the performance, a STAR-RIS-aided two-user downlink communication system is investigated for both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA). The outage probabilities, diversity orders, and power scaling laws under this design are studied and compared with the performance upper and lower bounds. Numerical simulations show that the proposed diversity preserving phase-shift configuration strategy for the STAR-RIS achieves the same diversity order as the STAR-RISs assuming independent phase-shift, and achieves a comparable power scaling law with only 4 dB power reduction.\",\n \"Title: Downlink Multi-RIS Aided Transmission in Backhaul Limited Networks\\nYear: 2022\\n\\nAbstract: This letter proposes an analytical framework for multi-reconfigurable intelligent surface (RIS) aided networks with limited backhaul capacity, where a simple symmetric structure is considered to explore the characteristics of multi-RIS systems with coherent transmissions. By using the Gamma distribution to model the composite RIS-aided channels, closed-form expressions in terms of the outage probability and the ergodic rate are derived. The theoretical results provide two design guidelines: 1) the minimum outage can be achieved by deploying the assisted RISs at certain locations; 2) the rate performance is bounded, and an optimal number of assisted RISs exists for rate maximization. Simulations verify our analysis and demonstrate the backhaul capacity is the bottleneck for multi-RIS systems. Compared with single-RIS systems, multi-RIS systems require a minimal backhaul capacity to ensure the performance gain.\",\n \"Title: UAV-Enabled Non-Orthogonal Multiple Access Networks for Ground-Air-Ground Communications\\nYear: 2022\\n\\nAbstract: Both unmanned aerial vehicle (UAV) and non-orthogonal multiple access (NOMA) have gradually become promising technologies for the fifth generation (5G) driven green Internet-of-Things (IoT) networks on account of their unique advantages of massive connections, higher spectral efficiency and flexibility. Motivated by this, we propose a 3-hop NOMA UAV-aided green communication network framework, where UAVs serve as aerial relays to support two groups of ground users. A stochastic geometry approach is invoked to model the spatial positions of the two group users. Under the realistic assumption, imperfect successive interference cancelation (ipSIC) is considered. To evaluate the performance of the proposed framework, theoretical expressions are derived to facilitate the outage performance evaluation of the far user (FU) and the near user (NU). Moreover, the asymptotic behaviors for the outage probability (OP) of both the FU and the NU in the high signal-to-noise ratio (SNR) regime are explored by obtaining diversity orders. Finally, the system throughputs under the delay-limited transmission mode are investigated. Numerical results confirm that: 1) For uplink transmission, there exist outage floors for the OP of both ipSIC and perfect SIC (pSIC) due to interference from the NU; 2) For downlink transmission, an outage floor exists for the OP of the NU under the condition of ipSIC; 3) For uplink NOMA/orthogonal multiple access (OMA) transmission, the outage performances of both the FU and the NU with NOMA outperform OMA in the low SNRs, while OMA has better performance in the high SNR regime; 4) For downlink NOMA/OMA, the outage performances of both the FU and the NU under pSIC outperform OMA.\",\n \"Title: Effective Capacity Analysis of STAR-RIS-Assisted NOMA Networks\\nYear: 2022\\n\\nAbstract: This letter studies the performance of the simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided non-orthogonal multiple access (NOMA) networks in support of ultra-reliable low-latency communications. We adopt effective capacity (EC) as the metric to explore the delay requirements of NOMA users. Specifically, the analytical expressions of the EC are obtained for the network with a pair of NOMA users on the different sides of the STAR-RIS. Furthermore, the high signal-to-noise ratio (SNR) slope and high SNR power offset are invoked to provide asymptotic analysis of the ECs in high SNR. Some insightful conclusions are drawn from the simulations: 1) the EC of near user \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$({U_{n}})$ </tex-math></inline-formula>\\n increases linearly while the EC of far user \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">$({U_{m}})$ </tex-math></inline-formula>\\n tends to be a constant in the high SNR; 2) comparing with STAR-orthogonal multiple access and conventional RIS, the use of STAR-RIS NOMA increases the ECs of \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">${U_{n}}$ </tex-math></inline-formula>\\n and overall network; 3) increasing the number of STAR-RIS elements is an effective strategy to improve the ECs of both \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">${U_{n}}$ </tex-math></inline-formula>\\n and \\n<inline-formula xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\"> <tex-math notation=\\\"LaTeX\\\">${U_{m}}$ </tex-math></inline-formula>\\n.\",\n \"Title: Computation Capacity Enhancement by Joint UAV and RIS Design in IoT\\nYear: 2022\\n\\nAbstract: Mobile-edge computing (MEC) networks are facing limited coverage and harsh wireless transmission environments that severely hinder the computation capacity of the Internet-of-Things (IoT) devices. To overcome these issues, this article proposes a novel MEC framework empowered by an unmanned aerial vehicle (UAV) relay and a reconfigurable intelligence surface (RIS). To fully exploit the potentials in terms of computation enhancement brought by the joint UAV and RIS design, we formulate a max–min computation capacity problem via determining the uplink signal detection, active beamforming of UAV, passive beamforming of RIS, time slot partition, computation bits of UAV, and UAV’s trajectory. We develop a concave–convex procedure (CCCP)-based algorithm in an alternating optimization manner over three subproblems to solve the formulated problem. It finds that the CCCP-based algorithm is conducive to decouple the intractable expressions by converting them into new but tractable second-order cone (SOC) constrains. To evaluate the performance of the proposed CCCP-based algorithm, we later design a direct algorithm by exploiting the implicit convexity of the problem. Simulation results demonstrate that the proposed CCCP-based algorithm derives a comparable performance as the direct algorithm, and achieves about 2.57-Mb max-min computation capacity higher compared with the straight flight case, and 8.08-Mb max–min computation capacity higher compared with the case without RIS, which validate the superiority of the joint UAV and RIS design for computation enhancement.\",\n \"Title: Cellular-Connected Multi-UAV MEC Networks: An Online Stochastic Optimization Approach\\nYear: 2022\\n\\nAbstract: In this paper, we consider a mobile edge computing (MEC) network where multiple cellular-connected unmanned aerial vehicles (UAVs) can offload their computation tasks to multiple ground base stations (GBSs). In practice, the UAVs are generally unable to master stochastic information of task arrival and channel changes in advance, which may cause a severe issue in terms of energy consumption. Therefore, we formulate a stochastic optimization problem with the goal of minimizing the average weighted sum energy consumption, by jointly optimizing UAV-GBS associations, communication and computation resource allocation, and three-dimensional (3D) UAV trajectories, during which a velocity-triggered penalty term (VTPT) is designed to suppress a large amount of the energy consumption of the UAVs. To handle the stochastic problem, we propose an online resource allocation and trajectory optimization algorithm with outer and inner structures. The outer structure transforms the original problem to a deterministic one by applying the Lyapunov-based optimization framework. The inner structure solves the obtained deterministic problem via the Lagrange duality method and the successive convex approximation technique, based on the block coordinate descent framework. Numerical results demonstrate that: 1) VTPT dramatically decreases the UAVs’ energy consumption, and 2) the proposed algorithm not only reduces the energy consumption but also ensures the computation queue stability compared with other benchmark schemes.\",\n \"Title: How Can Reconfigurable Intelligent Surfaces Drive 5G-Advanced Wireless Networks: A Standardization Perspective\\nYear: 2022\\n\\nAbstract: The reconfigurable intelligent surface (RIS) is a promising technology for achieving smart radio environment in future wireless networks with significantly reduced cost. While most existing works focused on several theoretical challenges of RIS empowered wireless communication systems, the engineering and standardization aspects taking into account practical implementation constraints regarding deployment costs and compatibility have not been investigated clearly yet. To fill this gap, this paper provides an overview of the RIS enabled opportunities for the fifth generation (5G) Advanced and also highlight the critical requirements and challenges from a standardization perspective. In particular, the use cases and deployment of RIS, the realistic channel models, the smart RIS control, and the interference management of multiple RISs are elaborated.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":134,"string":"134"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":83,"string":"83"}}},{"rowIdx":84,"cells":{"question_id":{"kind":"string","value":"Nripendra P Rana"},"question":{"kind":"string","value":"Generate an abstract for the title \"Digital Payments Adoption: An Analysis of Literature.\" using the following items: 1. Digital payments\n2. Developing countries\n3. Mobile payment adoption\n4. Inhibitors to digital payments\n5. Consumer behavior towards mobile payments"},"answer":{"kind":"string","value":"Digital payments (mainly enabled by mobile devices) have huge potential to change lives of millions of people in developing countries by offering financial services to the unbanked masses. Despite its potential digital payment methods have not been widely and successfully adopted in the developing countries. In order to ascertain the various drivers and inhibitors behind digital payment adoption, this study did a review of research on digital and mobile payment adoption and use. Results of this literature analysis revealed performance expectancy/perceived usefulness as most significant determinant of consumer’s behavioral intention to use mobile payments followed by perceived ease of use (PEOU). Perceived risk was found as major inhibitor to the adoption of mobile payments. Also majority of studies employed TAM and its extension to understand consumer adoption to mobile payment followed by UTAUT."},"correct_answer":{"kind":"string","value":"Digital payments (mainly enabled by mobile devices) have huge potential to change lives of millions of people in developing countries by offering financial services to the unbanked masses. Despite its potential digital payment methods have not been widely and successfully adopted in the developing countries. In order to ascertain the various drivers and inhibitors behind digital payment adoption, this study did a review of research on digital and mobile payment adoption and use. Results of this literature analysis revealed performance expectancy/perceived usefulness as most significant determinant of consumer’s behavioral intention to use mobile payments followed by perceived ease of use (PEOU). Perceived risk was found as major inhibitor to the adoption of mobile payments. Also majority of studies employed TAM and its extension to understand consumer adoption to mobile payment followed by UTAUT."},"documents":{"kind":"list like","value":["Title: Diversity and diffusion of theories, models, and theoretical constructs in egovernment research\nYear: 2011\n\nAbstract: After more than a decade of research in the field of e-government, it is now timely and appropriate to reflect upon the overall developmental directions in the area. The purpose of this paper is to explore research progress to date by systematically analysing the existing body of knowledge on egovernment related issues. Usable data relating to e-government research currently available were collected from 434 research articles. Based on the investigation of the various studies, our findings reveal that survey was the most utilised research method, and the Technology Acceptance Model was the most utilised theory to explain research models. Although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their exploitation by e-government researchers appears largely random in approach. The paper also presents limitations and further research directions.","Title: Evaluating The Validity Of Is Success Models For The Electronic Government Research: An Empirical Test And Integrated Model\nYear: 2013\n\nAbstract: The purpose of this paper is to compare and evaluate the validity of Information systems (IS) success models such as DeLone and McLean's (1992), Seddon's (1997), and DeLone and McLean's (2003) IS success models for an e-government application called the Online Public Grievance Redressal System (OPGRS) in context of India. The paper also provides an integrated model of IS success based on the comparison of the three well-known IS success models. All the existing models of IS success are not considered in their original shapes as this research is not using the variables such as use, individual impact, organizational impact from DeLone and McLean (1992) IS success model, use and net benefits from DeLone and McLean (2003) IS success model, and other measures of net benefits of IS use including net benefits to individuals, organizations, and society, and expectations about the net benefits of future IS use from Seddon's (1997) IS success model. The proposed model contains the additional constructs relevant to e-government research including complexity, trust, and facilitating conditions and found that the model performs quite satisfactorily as far as the success of the OPGRS system is concerned. The paper also discusses its limitations, provides implications for theory and practice, and proposed future lines of research which will allow the researchers, practitioners, and government to leverage the full potential of the OPGRS system to curb and eradicate corruption and to build a transparent and sanitized society.","Title: Reflecting on E-Government Research: Toward a Taxonomy of Theories and Theoretical Constructs\nYear: 2011\n\nAbstract: After more than a decade of research in the field of e-government, it is now timely and appropriate to reflect upon the overall developmental directions in the area. This paper explores research progress to date by systematically analyzing the existing body of knowledge on e-government related issues, and reveal if there is lack of theoretical development and rigor in the area. Usable data relating to e-government research currently available were collected from 779 research articles identified from the ISI Web of Knowledge database, and by manually identifying relevant articles from dedicated journals on electronic government such as Transforming Government: People, Process, and Policy TGPPP, Electronic Government, an International Journal EGIJ, and International Journal of Electronic Government Research IJEGR. Based on the investigation of the various studies, findings reveal that generic e-government applications were explored more than any specific applications, and the technology acceptance model TAM was the most utilized theory to explain research models. Although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their utilization by e-government researchers appears largely random in approach. The paper also presents limitations and further research directions for future researchers.","Title: E-government adoption research: an analysis of the employee's perspective\nYear: 2013\n\nAbstract: This paper works toward analysing the employee's perspective of e-government adoption literature. The purpose of this paper is to provide a review of current literature pertaining to electronic government research in order to observe basic trends and highlight promising lines of inquiry. Of an initial search resulting in 448 articles published in between 2000-2011, 134 were found to discuss adoption of e-government services from an employee's perspective and included in our study. Of these 134 articles, 77 reported qualitative research, 52 quantitative, and five reported activity belonging to both categories. The findings suggest that there is currently a relative lack of theoretical development and rigor in the area, and although many aspects such as job relevance, security, perceived benefits, anxiety, and perceived quality are clearly significant as far as employee's adoption is concerned, they have not been investigated to their potential, and there remains much opportunity for researchers to shape and develop the field. Restricting our analysis to theoretical constructs and their frequency may not provide a full picture of the relevance of the constructs.","Title: A Meta-Analysis Of The Unified Theory Of Acceptance And Use Of Technology (Utaut)\nYear: 2011\n\nAbstract: The originating article of the Unified Theory of Acceptance and Use of Technology (UTAUT) has been cited by a large number of studies. However, a detailed examination of such citations revealed that only small proportion (43 articles) of these citations actually utilized the theory or its constructs in their empirical research for examining IS/IT related issues. In order to examine whether the theory is performing consistently well across various studies, this research aims to undertake a statistical meta-analysis of findings reported in 43 published studies that have actually utilized UTAUT or its constructs in their empirical research. Findings reveal the underperformance of theory in subsequent studies in comparison to the performance of UTAUT reported in the originating article. The limitations experienced while conducting the metaanalysis, recommendations, and the future scope for the further research in this area have also been briefly explained in concluding section.","Title: Investigating success of an e-government initiative: Validation of an integrated IS success model\nYear: 2015\n\nAbstract: The purpose of this paper is to examine the success (by measuring intention to use and user satisfaction) of the online public grievance redressal system (OPGRS) from the perspective of the citizens of India. The success of this e-government system is examined using an integrated IS success model. The model developed includes the constructs such as system quality, information quality, service quality, perceived usefulness, perceived ease of use, perceived satisfaction, perceived risk, and behavioral intention. The proposed integrated research model of IS was validated using the response taken from 419 citizens from different cities of India. The empirical outcomes provided the positive significant connections between all 12 hypothesised relationships between eight constructs. The empirical evidence and discussion presented in the study can help the government to improve upon and fully utilise the potential of the OPGRS as a useful tool toward a transparent and corruption free country.","Title: The unified theory of acceptance and use of technology (UTAUT): a literature review.\nYear: 2015\n\nAbstract: Purpose - The purpose of this paper is to perform a systematic review of articles that have used the unified theory of acceptance and use of technology (UTAUT). Design/methodology/approach - The results produced in this research are based on the literature analysis of 174 existing articles on the UTAUT model. This has been performed by collecting data including demographic details, methodological details, limitations, and significance of relationships between the constructs from the available articles based on the UTAUT. Findings - The findings indicated that general purpose systems and specialized business systems were examined in the majority of the articles using the UTAUT. The analysis also indicated that cross-sectional approach, survey methods, and structural equation modelling analysis techniques were the most explored research methodologies whereas SPSS was found to be the largely used analysis tools. Moreover, the weight analysis of independent variables indicates that variables such as performance expectancy and behavioural intention qualified for the best predictor category. Moreover, the analysis also suggested that single subject or biased sample as the most explored limitation across all studies. Research limitations/implications - The search activities were centered on occurrences of keywords to avoid tracing a large number of publications where these keywords might have been used as casual words in the main text. However, we acknowledge that there may be a number of studies, which lack keywords in the title, but still focus upon UTAUT in some form. Originality/value - This is the first research of its type which has extensively examined the literature on the UTAUT and provided the researchers with the accumulative knowledge about the model.","Title: Examining the Success of the Online Public Grievance Redressal Systems: An Extension of the IS Success Model\nYear: 2015\n\nAbstract: The purpose of this article is to examine the success of the online public grievance redressal system from the perspective of the citizens of India. The empirical outcomes provided the positive significant connections between all 13 hypothesized relationships among the seven constructs. The empirical evidence and discussion presented in the study can help the Indian government to improve upon and fully utilize the potential of the online public grievance redressal system for transparent and corruption free country.","Title: Profiling Existing Research on Social Innovation in the Public Sector\nYear: 2014\n\nAbstract: This study explores the progress of social innovation research in a public sector context by systematically analyzing its existing body of knowledge to identify areas of societal impact and reveal areas of limitations and potential further research. The findings revealed that most of the studies on social innovation in the public sector are conceptual in nature. The article presents propositions based on the diagnosed limitations of research in the area.","Title: Can Marketing Strategies Enhance the Adoption of Electronic Government Initiatives?\nYear: 2014\n\nAbstract: This article assesses the role and likely impact of marketing on the adoption of e-government initiatives. Although the role of tactical marketing in increasing awareness and enhancing adoption has been recognised, strategies required for realising the benefits of marketing e-government services have not been forthcoming. Given that citizens' usage behaviour of e-government services remains sub-optimal and the potential contribution of marketing, we propose a set of marketing-based strategic approaches and argue that they can play an essential role in enhancing adoption of e-government initiatives and propelling citizen's engagement with e-governance. Based on citizens' differential levels of usage behaviour of e-government services and benefits sought from engaging in e-governance, this article classifies citizens into six distinct segments and suggests generic strategic approaches.","Title: A meta-analysis of existing research on citizen adoption of e-government\nYear: 2015\n\nAbstract: The purpose of this paper is to perform a weight-analysis and to undertake a meta-analysis of findings reported in published research on the adoption and diffusion of e-government. Usable data relating to e-government adoption research were collected from 103 empirical studies. Of those 103 articles, only 63 used a range of different constructs with appropriate correlation values required for performing a weight- and meta-analysis. Diagrammatic representation has been presented using significant as well as non-significant relationships from all 103 publications. A broader analysis of research on adoption and diffusion of e-government also reflects that although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their utilization by e-government researchers appears to be largely random in approach. This paper also acknowledges the theoretical contribution, the limitations of this study, and suggests further research directions for the continued work.","Title: Adoption of online public grievance redressal system in India: Toward developing a unified view.\nYear: 2016\n\nAbstract: The aim of this research is to develop a unified model of electronic government (e-government) system adoption and validate it using the data gathered from 419 citizens from few selected cities in India. In course of doing so, the research also evaluates the performance of nine well-known alternative theoretical models of information technology (IT) adoption including the unified theory of acceptance and use of technology (UTAUT). The results indicate that the proposed unified model for e-government adoption by this research has outperformed all other theoretical models by explaining highest 66% variance on behavioral intentions, adequately acceptable levels of fit indices, and significant relationships between each hypothesis. The research also provides its limitations and presents implications for theory and practice toward the end.","Title: Consumer adoption of mobile banking in Jordan: Examining the role of usefulness, ease of use, perceived risk and self-efficacy.\nYear: 2015\n\nAbstract: Purpose - The purpose of this paper is to propose and examine a conceptual model that best explains the key factors influencing Jordanian customers' intention to adopt mobile banking (MB). Design/methodology/approach - The proposed conceptual model was based on the Technology Acceptance Model (TAM). This was extended by adding perceived risk and self-efficacy as an external factors. Structural equation modelling (SEM) was conducted to analyse the data collected from the field survey questionnaires administered to a convenience sample of Jordanian banking customers. Findings - The results showed that behavioural intention is significantly influenced by perceived usefulness, perceived ease of use, and perceived risk. Research limitations/implications - Practical and theoretical implications for both Jordanian banks and researchers in the MB context are also discussed in the concluding section. Originality/value - MB-related issues are yet to be examined empirically in the Jordanian context. This submission has attempted to fill this gap by empirically examining some of the important factors influencing the adoption of MB from the Jordanian customers' perspective.","Title: Adoption of Mobile Banking in Jordan: Exploring Demographic Differences on Customers' Perceptions.\nYear: 2015\n\nAbstract: This study aims to explore whether Jordanian customers' perceptions on intention and adoption of Mobile banking (MB) services varies according to their demographic characteristics. As per the prior literature, five demographic factors, namely age, gender, income, education and customer's experience with computer and Internet have been considered in the current study. The required data were collected from the field survey questionnaires administered to a convenience sample of Jordanian banking customers. The major statistical results (mean and standard deviation) demonstrate that the customers' perceptions on intention and adoption of MB are likely to vary due to customers' demographic differences. According to the current study's findings, it was also noticed that despite the fact that the most of the sample respondents express a high intention to adopt MB, the adoption rate for the majority of MB services was low.","Title: Sentiment Analysis of Products' Reviews Containing English and Hindi Texts.\nYear: 2015\n\nAbstract: The online shopping is increasing rapidly because of its convenience to buy from home and comparing products from their reviews written by other purchasers. When people buy a product, they express their emotions about that product in the form of review. In Indian context, it is found that the reviews contain Hindi text along with English. It is also found that most of the Hindi text contains opinionated words like bahut achha, bakbas, pesa wasool etc. We have tried to find out different Hindi texts appearing in product reviews written on Indian E-commerce portals. We have also developed a system which takes all those reviews containing Hindi as well as English texts and find out the sentiment expressed in that review for each attribute of the product as well as a final review of the product.","Title: Driving Innovation Using Big Open Linked Data (BOLD) Panel\nYear: 2015\n\nAbstract: Governments have always retained public service data internally in their own systems with only limited information provided to the public and other stakeholders such as the business, charitable and NGO communities. However, the rapid advancement of ICTs coupled with electronic publishing via the Internet in the last decade in particular has enabled governments to exploit the potential of wider distribution and use of such data previously held in internal systems. The panellists will discuss how Big, Open and Linked Data (BOLD) can be utilized to drive innovation and what obstacles and challenges may be encountered. Empowering citizens, potential mis-use in identity theft, policy manipulation or market distortion, and the need to combine open data with closed sources will be discussed.","Title: A MapReduce Based Distributed Framework for Similarity Search in Healthcare Big Data Environment\nYear: 2015\n\nAbstract: Similarity search in the big data environment is a challenging task. Patient Similarity search (PaSi) is an important issue in healthcare network and data. The results of PaSi search may be highly useful for drawing different conclusions and decisions to improve healthcare systems. Such findings can also be useful for choosing the treatment paths for new patients. In this paper, we propose a MapReduce based framework as a solution to the PaSi problem in the context of a healthcare network imagined to be implemented considering the healthcare centers of India. It is assumed that such a healthcare network will be implemented in future over the Government of India cloud known as GI cloud or 'MeghRaj'. The paper also discusses the associated implementation challenges of the proposed framework and the query handling approach for the proposed framework to solve the PaSi problem is stated. Finally, the paper outlines the future scope of the work.","Title: Citizen's Adoption of an E-Government System: Validating the Extended Theory of Reasoned Action TRA\nYear: 2015\n\nAbstract: AbstractThe study explores the adoption of an electronic government e-government system called online PAN card registration system OPCRS in context of India. The study validates the extended theory of reasoned action TRA to understand the impact of some of its factors on the citizen's intention to adopt this system. The proposed research model is extended with the variables including perceived usefulness, perceived trust, and self-efficacy as antecedents of attitude and subjective norm, which are the core constructs of the TRA. The eight hypotheses were formulated between six constructs of the proposed extended TRA. The proposed research model is validated using the usable sample of data gathered from 377 respondents. The data was analysed using AMOS 22.0. The empirical findings of the proposed research model indicated the significant relationships of all proposed hypotheses. The study also provides its limitations, future research directions, and implications for theory and practice toward the end.","Title: An Empirical Study of Facebook Adoption Among Young Adults in a Northeastern State of India: Validation of Extended Technology Acceptance Model (TAM).\nYear: 2016\n\nAbstract: The purpose of this paper is to explore the adoption of a social networking site called Facebook in context of a landlocked and one of the least populous states in India. The adoption of Facebook is examined by considering technology acceptance model (TAM) as a basic model along with additional constructs such as subjective norm and perceived trust in it. The data were collected from 202 young adults from couple of degree level colleges from one of the least populous and landlocked states called Sikkim in India. The empirical outcomes provided the positive significant connections between nine hypothesised relationships among seven constructs. The article also discusses the resulting theoretical contributions for Facebook adoption and discusses practical implications of Facebook adoption for Facebook providers and users.","Title: A Systematic Review of Extant Literature in Social Media in the Marketing Perspective.\nYear: 2016\n\nAbstract: Social media applications have been extensively used and adopted by individuals and organisations in most aspects of daily life. Likewise, researchers have spent much effort in examining and exploring the effectiveness and efficiency of engaging such applications over the marketing context. This study, therefore, realizes the necessity of conducting a review of prior literature of social media over the marketing context especially in the light of the fact that only a small number of studies have been reviewed and conducted in this area. Accordingly, the aim of this study is to systematically review the current literature of social media in the marketing context. By reviewing approximately 71 articles, this study provides an overview of the main themes and trends covered by the relevant literature such as the role of social media on advertising, the electronic word of mouth, customers' relationship management, and firms' brands and performance.","Title: The changing landscape of IS project failure: an examination of the key factors.\nYear: 2017\n\nAbstract: Purpose - Information systems (IS) project failure has been a recurring problem for decades. The purpose of this paper is twofold: first, to examine the key factors that influence project failure and an analysis of the major areas that can have a significant impact on success; and second, to explore some of the key aspects that have an impact on project management performance from the practitioner perspective and discusses the problems faced by organizations in the closer integration of change and project management. Design/methodology/approach - This study critically reviews the IS failure literature developing a synthesized view of the key issues and common reasons for projects to fail. The approach taken in this study is one that focuses on a number of key questions that pull together the relevant themes in this genre of research whilst highlighting many of the implications for practitioners and organizations alike. Findings - Key questions remain on the underlying causes of instances of poor project management as an IS failure factor. The literature has omitted to develop a deeper analysis of the associations between failure factors and the potential causal relationships between these factors. The realization of project benefits relies on the success of both change and project management yet the formal integration of these two disciplines is constrained by separate standards bodies and an immature body of research. Research limitations/implications - This study is limited by its theoretical nature lacking an empirical element to provide a deeper analysis of IS failure factors and their interrelationships. This specific area is a recommendation for future research, where causal relationships between failure factors could be developed via a mathematic-based method such as interpretive structural modeling. Practical implications - With failure rates of IS projects still unacceptably high after decades of attempts to significantly change outcomes, a deeper analysis of this topic is required. The research gaps and recommendations for practitioners highlighted in this study have the potential to provide valuable contributions to this topic of research. Originality/value - The intent of this study is to present a new perspective of this genre of IS research that develops the main arguments and gaps in the literature from the practitioner viewpoint.","Title: Driving innovation through big open linked data (BOLD): Exploring antecedents using interpretive structural modelling.\nYear: 2017\n\nAbstract: Innovation is vital to find new solutions to problems, increase quality, and improve profitability. Big open linked data (BOLD) is a fledgling and rapidly evolving field that creates new opportunities for innovation. However, none of the existing literature has yet considered the interrelationships between antecedents of innovation through BOLD. This research contributes to knowledge building through utilising interpretive structural modelling to organise nineteen factors linked to innovation using BOLD identified by experts in the field. The findings show that almost all the variables fall within the linkage cluster, thus having high driving and dependence powers, demonstrating the volatility of the process. It was also found that technical infrastructure, data quality, and external pressure form the fundamental foundations for innovation through BOLD. Deriving a framework to encourage and manage innovation through BOLD offers important theoretical and practical contributions.","Title: Authenticity Of Geo-Location And Place Name In Tweets\nYear: 2017\n\nAbstract: The place name and geo-coordinates of tweets are supposed to represent the possible location of the user at the time of posting that tweet. However, our analysis over a large collection of tweets indicates that these fields may not give the correct location of the user at the time of posting that tweet. Our investigation reveals that the tweets posted through third party applications such as Instagram or Swarmapp contain the geo-coordinate of the user specified location, not his current location. Any place name can be entered by a user to be displayed on a tweet. It may not be same as his/her exact location. Our analysis revealed that around 12% of tweets contains place names which are different from their real location. The findings of this research can be used as caution while designing location-based services using social media.","Title: User Adoption Of Cashless Services In Indian Context - A Preliminary Analysis\nYear: 2017\n\nAbstract: The recent measures adopted by the Government of India for the financial reforms in the country has led to an urgent need of different modes for cashless services. India is a country of diverse culture inhabited by people having a wide range of demographic factors. It is, thus, essential to identify the significant factors that affect the individual's intention to adopt the cashless services. The main objective of this research is to analyse the users' behaviour towards several constructs that have been identified as the potential enablers of the high rate of adoption of cashless services in India. The study builds upon the Unified Theory of Acceptance and Use of Technology model and adds several new factors that are significant in the Indian context. Results obtained through descriptive statistics suggest that the identified constructs are perceived significant by the users in shaping their intentions towards the use of cashless services.","Title: Assessing Consumers' Intention To Adopt Mobile Internet Services In The Kingdom Of Saudi Arabia\nYear: 2017\n\nAbstract: This study was conducted with intention to provide a further understanding about the most predictive factors that could shape the customers' intention to adopt Mobile Internet services in the Kingdom of Saudi Arabia. Thus, and according to critical reviewing of the main body of literature over the relevant area, researchers were able to identify four main factors that could have impact on the behavioural intention. These factors are performance expectancy, effort expectancy, hedonic motivation, and awareness that all are proposed in the same conceptual model of the current study. The current study data was collected from three main cities in Saudi Arabia (Jeddah, Riyadh and Dammam). Then structural equation modelling using AMOS was adopted to examine the proposed model and verify the research hypotheses. Statistical results largely supported the factors included as all of these factors have a significant influence on the customers' intention to adopt Mobile Internet services. Hopefully, such results will provide accurate clues for designers and practitioners to focus more on the most important aspects that attract attention from customers in the Kingdom of Saudi Arabia.","Title: Exploring the Role of Social Media in e-Government: an Analysis of Emerging Literature\nYear: 2017\n\nAbstract: Driven by rising citizen expectations and the need for government innovation, social media has become a key component of e-government in a very short period of time. A number of research papers have been published on the role of social media in e-government in last few years. This study performs a literature review of the articles on the use of social media for getting access to e-government websites from the perspective of citizens. The database search through Scopus resulted in 115 articles, which formed the basis of this literature review. The keywords analysis of these articles indicates that 'e-government' and 'social media' were the most explored keywords across these studies. The methodological analysis indicates that the majority of the studies were analytical/conceptual/descriptive/theoretical in nature. The theoretical analysis, however, indicates that there is a lack of such research that has used some well-established theories or models to understand this concept. The review of literature further indicates that research themes such as 'electronic participation', 'engagement', 'transparency', 'communication/ interaction', 'trust' and 'collaboration' were found as some of the most frequently used categories under this area of research.","Title: A Systematic Review of Citations of UTAUT2 Article and Its Usage Trends.\nYear: 2017\n\nAbstract: Unified Theory of Acceptance and Use of Technology (UTAUT) is considered as the most comprehensive theory in Information Systems (IS) research to understand technology acceptance across various use contexts. The theory was extended to consumer context by incorporating three external constructs. This extended version is referred as UTAUT2. Although UTAUT2 is relatively new, the increasing number of citations is a testimony to the fact that it’s popular amongst IS researchers especially for examining consumer- focused issues. However, none of the existing studies attempted to analyze the pattern of UTAUT2 citations. This study is aimed to undertake a systematic review of 650 citations with a motivation to fulfill this research gap. The study revealed that majority of the studies i.e. 77% cited UTAUT2 for general citation purpose. However, the remaining 23%, even if they utilized UTATU2, did so in combination with external theories where the moderators of UTAUT2 were rarely considered.","Title: Advances in Electronic Government (e-Government) Adoption Research in SAARC Countries.\nYear: 2017\n\nAbstract: This paper profiles the research activities that have been published on e-government adoption in the context of South Asian Association for Regional Cooperation (SAARC) countries. Our analysis includes variables such as the years of publication, journals most often publishing papers on e-government adoption, countries in which the research activity was conducted, the authors most active in the subject area, keywords analysis, methodological analysis, technology and respondents contexts, analysis of theories or models used and analysis of limitations and future research directions extracted from 48 research papers that were extracted from Scopus database using some key terminologies related to e-government, adoption and eight SAARC countries. This is the first study that has comprehensively examined the analysis of e-government adoption literature in these eight countries’ context. The results of this research provide some promising lines of inquiry that have been largely neglected along with those that have received a much larger attention.","Title: An empirical validation of a unified model of electronic government adoption (UMEGA).\nYear: 2017\n\nAbstract: In electronic government (hereafter e-government), a large variety of technology adoption models are employed, which make researchers and policymakers puzzled about which one to use. In this research, nine well-known theoretical models of information technology adoption are evaluated and 29 different constructs are identified. A unified model of e-government adoption (UMEGA) is developed and validated using data gathered from 377 respondents from seven selected cities in India. The results indicate that the proposed unified model outperforms all other theoretical models, explaining the highest variance on behavioral intention, acceptable levels of fit indices, and significant relationships for each of the seven hypotheses. The UMEGA is a parsimonious model based on the e-government-specific context, whereas the constructs from the original technology adoption models were found to be inappropriate for the e-government context. By using the UMEGA, relevant e-government constructs were included. For further research, we recommend the development of e-government-specific scales.","Title: Social media in marketing: A review and analysis of the existing literature.\nYear: 2017\n\nAbstract: •A growing number of research studies have addressed the issues of social media in marketing.•This research reviewed 144 studies on social media in marketing context.•Seven key themes emerged from the literature.•Promotional and advertising efforts, e-WOM and CRM are some prominent themes.•Facebook has been the most frequently used social media platform examined.","Title: Use of Social Media in Citizen-Centric Electronic Government Services: A Literature Analysis\nYear: 2017\n\nAbstract: AbstractThis article undertakes a literature review on such articles on social media and citizen-centric e-government services. This research uses 139 articles to perform the intended literature review. The keywords analysis of these articles indicates that Web 2.0, participation and open government/open data were some of the frequently used keywords in addition to the two major themes of e-government and social media on which all the articles were searched for. The analysis of research methods indicated that majority of the studies were analytical, conceptual, descriptive, or theoretical in nature. The theoretical analysis however indicated that there is a lack of theory-based research in this area. The review of literature indicated that research themes such as electronic participation, engagement, transparency, communication/interaction, trust, security and collaboration are some of the most frequently used categories under this area of research. A research framework has also been proposed from the key themes emerging from the review.","Title: An empirical examination of antecedents determining students' usage of clickers in a digital marketing module.\nYear: 2018\n\nAbstract: As more and more educational institutions are integrating new technology such as clickers into their learning system, it becomes increasingly essential to have an understanding of studentsu0027 perceptions about such technology on their overall learning process. The incorporation of clickers into teaching instructions has created implications for teaching practices and student satisfaction. The purpose of this research is to understand student use and satisfaction with clickers in a large undergraduate digital marketing class in a British university. To do so, we propose a conceptual model based on information systems (IS) success models to understand studentu0027s usage behaviour and satisfaction with clickers. The data were analysed based on 138 valid responses gathered from the students, where clickers are effectively used for teaching and learning purposes. The results provided a strong support for all eight hypothesised relationships and adequate variance on its key dependent variables in the proposed resear...","Title: The Impact of Social Media on Consumers' Acculturation and Purchase Intentions.\nYear: 2018\n\nAbstract: Social media has emerged as a significant and effective means of assisting and endorsing activities and communications among peers, consumers and organizations that outdo the restrictions of time and space. While the previous studies acknowledge the role of agents of culture change, it largely remains silent on the role of social media in influencing acculturation outcomes and consumption choices. This study uses self-administered questionnaire to collect data from 514 Turkish-Dutch respondents and examines how their use of social media affects their acculturation and consumption choices. This research makes a significant contribution to consumer acculturation research by showing that social media is a vital means of culture change and a driver of acculturation strategies and consumption choices. This study is the first to investigate the role of social media as an agent of culture change in terms of how it impacts acculturation and consumption. The paper discusses implications for theory development and for practice.","Title: Advances in Social Media Research: Past, Present and Future.\nYear: 2018\n\nAbstract: Social media comprises communication websites that facilitate relationship forming between users from diverse backgrounds, resulting in a rich social structure. User generated content encourages inquiry and decision-making. Given the relevance of social media to various stakeholders, it has received significant attention from researchers of various fields, including information systems. There exists no comprehensive review that integrates and synthesises the findings of literature on social media. This study discusses the findings of 132 papers (in selected IS journals) on social media and social networking published between 1997 and 2017. Most papers reviewed here examine the behavioural side of social media, investigate the aspect of reviews and recommendations, and study its integration for organizational purposes. Furthermore, many studies have investigated the viability of online communities/social media as a marketing medium, while others have explored various aspects of social media, including the risks associated with its use, the value that it creates, and the negative stigma attached to it within workplaces. The use of social media for information sharing during critical events as well as for seeking and/or rendering help has also been investigated in prior research. Other contexts include political and public administration, and the comparison between traditional and social media. Overall, our study identifies multiple emergent themes in the existing corpus, thereby furthering our understanding of advances in social media research. The integrated view of the extant literature that our study presents can help avoid duplication by future researchers, whilst offering fruitful lines of enquiry to help shape research for this emerging field.","Title: understanding 'development' from the perspective of e-government, digital divide and ICT4D literature: a research agenda.\nYear: 2018\n\nAbstract: This paper asserts that considering the growing importance and significance of e-Government initiatives around the world and the increasing priority it has on governmentsu0027 agendas and investment costs, a more comprehensive understanding of u0027developmentu0027 is needed to complement what we already know about e-Government initiatives. This submission makes the case for why the issue of u0027developmentu0027 should be studied in more detail in e-Government research and aims to clarify the conceptualization and understanding of u0027developmentu0027 as it pertains to the use of ICTs in the digital government domain, drawing upon literature in two related research domains: Digital Divide and ICT for Development (ICT4D). E-Government research currently cuts short at understanding factors that affect the adoption and implementation of e-Government initiatives and tends to converse around the concept of u0027developmentu0027 at a general level. The literature in Digital Divide and ICT4D overcomes some of the perceived shortcomings of the e-Government literature, largely the issue of development in relation to citizens and the importance of considering context in more detail. By undertaking research using a case study approach within the UK and Tanzania, the proposed study will help to understand the impact of e-Government initiatives on citizensu0027 development and what this actually means over a longer period of time beyond the implementation stage. Such understanding is important to ensure that the very goals of e-Government initiatives are realised in relation to the context in which initiatives are deployed. By understanding from the e-Government perspective what development equates to and how it could possibly be measured can help in the design and rollout of future initiatives and can be considered to be positive steps towards achieving the UNu0027s Millennium Development Goals.","Title: Ranking online consumer reviews.\nYear: 2019\n\nAbstract: •A regression prediction model is proposed to rank the reviews based on their quality.•Results reveal that training the model only on high quality reviews performed better.•We use two new features product description data and customer question answer data.","Title: Citizens' Awareness, Acceptance and Use of Mobile Government Services in India: An Exploratory Research.\nYear: 2018\n\nAbstract: The development of mobile technology is not only changing the way business is run, as evidenced by the fast growth of mobile commerce, but also facilitating the transformation in a way that governments deliver their services. Mobile government is one area that has received very little research, but it can have a tremendous impact on the way citizens engage with their government. This research will analyse the data gathered from 25 respondents through online survey on the various aspects of mobile government and in India and their views on some of the key questions related to the use of mobile government in the country.","Title: Identifying reputation collectors in community question answering (CQA) sites: Exploring the dark side of social media.\nYear: 2018\n\nAbstract: •The paper identifies users who post and motivate others to post low quality and duplicate contents on CQA sites.•The good guys are called Caretakers and bad guys are considered as Reputation Collectors.•A graph based methodology was employed to derive the characteristic of Reputation Collectors and Caretakers.•The algorithms have been developed to identify the Reputation Collectors and Caretakers.•The results indicate that 1.05% of Reputation Collectors post 18.88% of low-quality answers.","Title: Factors influencing e-diplomacy implementation: Exploring causal relationships using interpretive structural modelling.\nYear: 2018\n\nAbstract: Electronic diplomacy (E-diplomacy) is the use of technology by nations to define and establish diplomatic goals and objectives and to efficiently carry out the functions of diplomats. These functions include representation and promotion of the home nation, establishing both bilateral and multilateral relations, consular services and social engagement. It encapsulates the adoption of multiple ICT tools over the Internet to support a nation's interests in other countries while ensuring that foreign relations are improved between the countries. Given its embryonic nature, little scholarly research has been undertaken to study its influence on diplomatic functions and the various factors that influence its implementation. This paper applies the Interpretative Structural Modelling (ISM) methodological approach to identify factors that impact the implementation of e-diplomacy and to determine their causal relationship and rankings. This study applies the ISM methodology to the subject of e-diplomacy. The ISM-based model provides a framework for practitioners to aid decision-making and manage the implementation of e-diplomacy.","Title: Exploring barriers of m-commerce adoption in SMEs in the UK: Developing a framework using ISM.\nYear: 2019\n\nAbstract: •The concept of m-commerce has grown exponentially within business in the last decade.•The paper aims to understand barriers of m-commerce adoption in SMEs in Wales.•The paper used Interpretive Structural Modelling and MICMAC to develop a framework.•A large number of the barriers of m-commerce adoption have high levels of driving power.•The findings indicated perceived risk as the key driving barrier of m-commerce adoption.•The lack of customer trust and confidence depends the most on all other variables.","Title: Consumer use of mobile banking (M-Banking) in Saudi Arabia: Towards an integrated model.\nYear: 2019\n\nAbstract: •M-Banking is one of the most promising technologies that could prove to have considerable value to both banks and customers.•This study investigates factors that could predict the use of M-Banking, customer satisfaction and customer loyalty.•This study proposes a comprehensive conceptual model that clarifies the use of M-Banking from the perspective of Saudi users.•A questionnaire survey was conducted to collect the required data from convenience sampling of Saudi bank customers.•This study would consider the adoption of numeric data in order to inferentially analyse them using SEM.","Title: Mobile applications in government services (mG-App) from user's perspectives: A predictive modelling approach.\nYear: 2018\n\nAbstract: Mobile applications are becoming a preferred delivery method for the government sector and contributing to more convenient and timely services to citizens. This study examines the intention to use mobile applications for the government services (mG-App) in Oman. This study extended the Unified Theory of Acceptance and Use of Technology (UTAUT) model by including two constructs namely trust and information quality. Data were collected from 513 mobile application users across Oman. The research model was analysed in two stages. First, structural equation modelling (SEM) was employed to determine significant determinants affecting users' acceptance of mG-App. In the second stage, a neural network model was used to validate SEM results and determine the relative importance of determinants of acceptance of mG-App. The findings revealed that trust and performance expectancy are the strongest determinants influencing the acceptance of mG-App. The findings of this research have provided theoretical contributions to the existing research on mG-App and practical implications to decision-makers involved in the development and implementation of mG-App in in Oman.","Title: Re-examining the Unified Theory of Acceptance and Use of Technology (UTAUT): Towards a Revised Theoretical Model\nYear: 2019\n\nAbstract: Based on a critical review of the Unified Theory of Acceptance and Use of Technology (UTAUT), this study first formalized an alternative theoretical model for explaining the acceptance and use of information system (IS) and information technology (IT) innovations. The revised theoretical model was then empirically examined using a combination of meta-analysis and structural equation modelling (MASEM) techniques. The meta-analysis was based on 1600 observations on 21 relationships coded from 162 prior studies on IS/IT acceptance and use. The SEM analysis showed that attitude: was central to behavioural intentions and usage behaviours, partially mediated the effects of exogenous constructs on behavioural intentions, and had a direct influence on usage behaviours. A number of implications for theory and practice are derived based on the findings.","Title: Barriers to the Development of Smart Cities in Indian Context\nYear: 2019\n\nAbstract: Smart city development is gaining considerable recognition in the systematic literature and international policies throughout the world. The study aims to identify the key barriers of smart cities from a review of existing literature and views of experts in this area. This work further makes an attempt on the prioritisation of barriers to recognise the most important barrier category and ranking of specific barriers within the categories to the development of smart cities in India. Through the existing literature, this work explored 31 barriers of smart cities development and divided them into six categories. This research work employed fuzzy Analytic Hierarchy Process (AHP) technique to prioritise the selected barriers. Findings reveal that ‘Governance’ is documented as the most significant category of barriers for smart city development followed by ‘Economic; ‘Technology’; ‘Social’; ‘Environmental’ and ‘Legal and Ethical’. In this work, authors also performed sensitivity analysis to validate the findings of study. This research is useful to the government and policymakers for eradicating the potential interferences in smart city development initiatives in developing countries like India.","Title: Event classification and location prediction from tweets during disasters\nYear: 2019\n\nAbstract: Social media is a platform to express one’s view in real time. This real time nature of social media makes it an attractive tool for disaster management, as both victims and officials can put their problems and solutions at the same place in real time. We investigate the Twitter post in a flood related disaster and propose an algorithm to identify victims asking for help. The developed system takes tweets as inputs and categorizes them into high or low priority tweets. User location of high priority tweets with no location information is predicted based on historical locations of the users using the Markov model. The system is working well, with its classification accuracy of 81%, and location prediction accuracy of 87%. The present system can be extended for use in other natural disaster situations, such as earthquake, tsunami, etc., as well as man-made disasters such as riots, terrorist attacks etc. The present system is first of its kind, aimed at helping victims during disasters based on their tweets.","Title: Involvement In Emergency Supply Chain For Disaster Management: A Cognitive Dissonance Perspective\nYear: 2018\n\nAbstract: An integrated process, interlinked operation and interoperable communication network amongst operating agencies are critical for developing an effective disaster management supply chain. The traditional managerial problems observed across disaster management operations are: non-cooperation among members, disrupted chain of commands, misuse of relief items, lack of information sharing, mistrust and lack of coordination. This study aims to understand the issues affiliated with negative attitude towards disaster management operations using theory of cognitive dissonance. A qualitative investigation was undertaken across 64 districts in Bangladesh. Five constructs were examined for their influences on attitude and behavioural intention of members participating in government emergency supply chain for disaster management. The results indicate that administrative conflict, political biasness and professional growth have significant effects on attitude. Impact of insecurity is non-significant on attitude. This research offers substantial theoretical contribution to the cognitive dissonance theory in the context of disaster management supply chain.","Title: Impact of internet of things (IoT) in disaster management: a task-technology fit perspective\nYear: 2019\n\nAbstract: Disaster management aims to mitigate the potential damage from the disasters, ensure immediate and suitable assistance to the victims, and attain effective and rapid recovery. These objectives require a planned and effective rescue operation post such disasters. Different types of information about the impact of the disaster are, hence, required for planning an effective and immediate relief operation. The IoT technology available today is quite mature and has the potential to be very useful in disaster situations. This paper analyzes the requirements for planning rescue operation for such natural disasters and proposes an IoT based solution to cater the identified requirements. The proposed solution is further validated using the task-technology fit (TTF) approach for analyzing the significance of the adoption of IoT technology for disaster management. Results from the exploratory study established the core dimensions of the task requirements and the TTF constructs. Results from the confirmatory factor analysis using PLS path modelling, further, suggest that both task requirements and IoT technology have significant impact on the IoT TTF in the disaster management scenario. This paper makes significant contributions in the development of appropriate constructs for modeling TTF for IoT Technology in the context of disaster management.","Title: Predicting changing pattern: building model for consumer decision making in digital market.\nYear: 2018\n\nAbstract: Purpose - Consumers have the multiple options to choose their products and services, which have a significant impact on the pattern of consumer decision making in digital market and further increases the challenges for the service providers to predict their buying pattern. In this sense, the purpose of this paper is to propose a structural hierarchy model for analyzing the changing pattern of consumer decision making in digital market by taking an Indian context. Design/methodology/approach - To accomplish the objectives, the research is conducted in two phases. An extensive literature review is performed in the first phase to list the factors related to the changing pattern of consumer decision making in digital market and then fuzzy Delphi method is applied to finalize the factors. In the second phase, fuzzy analytic hierarchy process (AHP) is employed to find the priority weights of finalized factors. The fuzzy set theory allows capturing the vagueness in the data. Findings - The findings obtained in this study shows that consumers are much conscious about innovative and trendy products as well as brand and quality; therefore, the service providers must think about these two most important factors so that they can able to retain their consumer in their online portal. Practical implications - The analysis shows that \"innovative and trendy\" is the first priority factor for the consumers followed by \"brand and quality\" and \"fulfilment and time energy.\" The proposed model can help the marketers and service providers in predicting customers' preferences and their changing pattern efficiently under vague surroundings. The outcomes of this research work not only help the service provider to update their products and services according to consumers' needs but can also help them to increase profit and minimize their risk. Originality/value - This work contributes to consumer research literature focusing on problem evaluation in the context of changing pattern of consumer decision making in digital era.","Title: Using privacy calculus theory to explore entrepreneurial directions in mobile location-based advertising: Identifying intrusiveness as the critical risk factor\nYear: 2019\n\nAbstract: Location-based advertising is an entrepreneurial and innovative means for advertisers to reach out through personalised messages sent directly to mobile phones using their geographic location. The mobile phone users' willingness to disclose their location and other personal information is essential for the successful implementation of mobile location-based advertising (MLBA). Despite the potential enhancement of the user experience through such personalisation and the improved interaction with the marketer, there is an increasing tension between that personalisation and mobile users' concerns about privacy. While the privacy calculus theory (PCT) suggests that consumers make privacy-based decisions by evaluating the benefits any information may bring against the risk of its disclosure, this study examines the specific risks and benefits that influence consumers' acceptance of MLBA. A conceptual model is proposed based on the existing literature and a standardised survey was developed and targeted at individuals with known interests in the subject matter. From these requests, 252 valid responses were received and used to evaluate the key benefits and risks of MLBA from the users' perspectives. While the results confirmed the importance of internet privacy concerns (IPC) as an important determinant, they also indicate that monetary rewards and intrusiveness have a notably stronger impact on acceptance intentions towards MLBA. Intrusiveness is the most important risk factor in determining mobile users' intentions to accept MLBA and therefore establishing effective means of minimising the perceived intrusiveness of MLBA can be expected to have the greatest impact on achieving effective communications with mobile phone users.","Title: Citizens' Perception About M-Government Services: Results From An Exploratory Survey\nYear: 2019\n\nAbstract: The development of mobile technology is facilitating the transformation in a way that governments deliver their services. Mobile government is one area that has received very little research, but it can have a tremendous impact on the way citizens engage with their government. This research analyses the data gathered from 81 respondents through online survey on the various aspects of mobile government and collects their views on some of the key questions related to the use of mobile government. The findings showed that although citizens are aware of the possibilities they hardly used mobile devices as a direct communication channel with government. Most users tend to use social media platforms and social media is used as an intermediary between government and citizens. The findings of this research also indicated that although the users are well aware of m-government services and own smartphones, only a handful of them use their mobiles for accessing government services.","Title: The battle of Brain vs. Heart: A literature review and meta-analysis of \"hedonic motivation\" use in UTAUT2.\nYear: 2019\n\nAbstract: Much of the scholarly debate on the extrinsic-intrinsic motivation dichotomy to date has focused on organisational context. However, the recent upsurge of technology use amongst individuals in non-organisational context has led to consumer-focused research model such as extended unified theory of acceptance and use of technology (UTAUT2). The objective of this study is to bring back much needed focus on motivation dichotomy from the consumer perspective. This involved a systematic review and meta-analysis of hedonic motivation an affective construct in UTAUT2 studies. The findings from 79 UTAUT2 empirical studies revealed that only 46 studies (58%) utilised hedonic motivation while the remaining 33 studies (42%) omitted the construct. Extrinsic motivation was the major driver of non-hedonic and non-significant hedonic motivation studies with individuals using technologies for utilitarian outcomes. Unlike UTAUT2, moderators association of hedonic motivation were non-significant in determining consumer intention to use technology. The findings also revealed an important association between hedonic motivation and effort expectancy, in addition to fruitful directions for research and practice.","Title: Elucidation of IS project success factors: an interpretive structural modelling approach\nYear: 2020\n\nAbstract: This study extends the debate surrounding the components of IS project success by reviewing success factors from the perspective of their interdependency and influence on each other. This research utilises interpretive structural modelling as the methodology and framework to develop the relationships between the selected factors. This approach is presented as a mechanism that can provide greater insight to the underlying causal interrelationships associated with IS project success and the successful transition to operations. The findings identify a number of key outcomes that have significant driving influence on other interconnected factors in the final model. This study highlights the benefits of an interpretive approach where IS factor interrelationships can be modelled to demonstrate potential influence on other connected factors thereby, increasing the chances of project success.","Title: Disaster management in Bangladesh: developing an effective emergency supply chain network\nYear: 2019\n\nAbstract: This study has addressed and identified the problems in managing the existing emergency supply chain of Bangladesh in all phases of operation in terms of the primary drivers of the supply chain. It has also attempted to conceptualize and suggest an effective emergency supply chain. In this context, a thorough field investigation in several districts was conducted among the employees of the organizations sharing common information with similar protocols and implications (interoperable). Information was collected from the employees of all the participating organizations involved in disaster management through a semi-structured questionnaire based survey. The respondents addressed and illustrated several interconnected reasons which are inhibiting proper forecasting, procurement, storage, identification of affected people, and distribution. The respondents pointed out that the mismatching of objectives in the different organizations resulted in non-interoperability among the participating organizations. These issues are related to the malfunctioning of management with multidimensional organizational conflicts. Reflecting those issues, an emergency supply chain for disaster management is proposed in this study.","Title: Smart Monitoring and Controlling of Government Policies Using Social Media and Cloud Computing\nYear: 2020\n\nAbstract: The governments, nowadays, throughout the world are increasingly becoming dependent on public opinion regarding the framing and implementation of certain policies for the welfare of the general public. The role of social media is vital to this emerging trend. Traditionally, lack of public participation in various policy making decision used to be a major cause of concern particularly when formulating and evaluating such policies. However, the exponential rise in usage of social media platforms by general public has given the government a wider insight to overcome this long pending dilemma. Cloud-based e-governance is currently being realized due to IT infrastructure availability along with mindset changes of government advisors towards realizing the various policies in a best possible manner. This paper presents a pragmatic approach that combines the capabilities of both cloud computing and social media analytics towards efficient monitoring and controlling of governmental policies through public involvement. The proposed system has provided us some encouraging results, when tested for Goods and Services Tax (GST) implementation by Indian government and established that it can be successfully implemented for efficient policy making and implementation.","Title: Impact of acculturation, online participation and involvement on voting intentions\nYear: 2019\n\nAbstract: This study examines the extent to which acculturation and enculturation orientations affect online political participation, political involvement and voting intentions among a sample of Turkish-Dutch immigrants. The study uses data from Turkish-Dutch participants. Structural Equations Modelling (SEM) is employed for assessing the relationships in the conceptualized model. The findings show that enculturation and acculturation influence online participation and involvement, which in turn, are related to voting intentions. The study further examines the mediating role of political involvement and online political participation. Political involvement mediates the relationships between enculturation and acculturation and voting intentions. The results further indicate the effect of online participation on voting intentions is mediated by political involvement. The study findings provide insights into offline and online cultural and civic engagement tendencies among an important immigrant segment that policy makers should consider in the future.","Title: The Effect Of Electronic Word Of Mouth Communications On Intention To Buy: A Meta-Analysis\nYear: 2020\n\nAbstract: The aim of this research is to synthesise findings from previous studies by employing weight and meta-analysis to reconcile conflicting evidence and draw a \"big picture\" of eWOM factors influencing consumers' intention to buy. By using the findings from 69 studies, this research identified best (e.g. argument quality, valence, eWOM usefulness, trust in message), promising (e.g. eWOM credibility, emotional trust, attitude towards website) and least effective (e.g. volume, existing eWOM, source credibility) predictors of intention to buy in eWOM research. Additionally, the effect size of each predictor was calculated by performing meta-analysis. For academics, understanding what influences consumers' intention to buy will help set the agenda for future research directions; for practitioners, it will provide benefit in terms of practical guidance based on detailed analysis of specific factors influencing consumers' intention to buy, which could enhance their marketing activities.","Title: Impact of COVID-19 pandemic on information management research and practice: Transforming education, work and life\nYear: 2020\n\nAbstract: •This paper presents an assessment of the key challenges of COVID-19 through an IS and IM lens.•The pandemic has forced governments and decision makers to reassess the use of IS and technology.•AI could engender better, more informed decision making during crisis management scenarios.•Privacy and security are key underlying concerns for many citizens during the pandemic.•In developing countries, the digital divide is most apparent due to social and cultural barriers.","Title: Social media analytics for end-users' expectation management in information systems development projects\nYear: 2021\n\nAbstract: Purpose This study, an exploratory research, aims to investigate social media users' expectations of information systems (IS) products that are conceived but not yet launched. It specifically analyses social media data from Twitter about forthcoming smartphones and smartwatches from Apple and Samsung, two firms known for their innovative gadgets. Design/methodology/approach Tweets related to the following four forthcoming IS products were retrieved from 1st January 2020 to 30th September 2020: (1) Apple iPhone 12 (6,125 tweets), (2) Apple Watch 6 (553 tweets), (3) Samsung Galaxy Z Flip 2 (923 tweets) and (4) Samsung Galaxy Watch Active 3 (207 tweets). These 7,808 tweets were analysed using a combination of the Natural Language Processing Toolkit (NLTK) and sentiment analysis (SentiWordNet). Findings The online community was quite vocal about topics such as design, camera and hardware specifications. For all the forthcoming gadgets, the proportion of positive tweets exceeded that of negative tweets. The most prevalent sentiment expressed in Apple-related tweets was neutral, but in Samsung-related tweets was positive. Additionally, it was found that the proportion of tweets echoing negative sentiment was lower for Apple compared with Samsung. Originality/value This paper is the earliest empirical work to examine the degree to which social media chatter can be used by project managers for IS development projects, specifically for the purpose of end-users' expectation management.","Title: Usage of augmented reality (AR) and development of e-learning outcomes: An empirical evaluation of students' e-learning experience\nYear: 2022\n\nAbstract: This study aims to examine students' experience of augmented reality learning applications (AR. LRP). Uses and gratifications theory was proposed as a theoretical foundation of the current study's conceptual model. Four dimensions of UGT benefits were proposed as key antecedences of the students' experience with AR.LRP: personal interactive benefits, social interactive benefits, affective benefits, and cognitive benefits. The model was also extended by considering the role of telepresence. Further, technostress was proposed on the current study to moderate the relationship between the aspects of UGT and e-learning experience. A sample size of 500 undergraduate students from the four largest Universities in Saudi Arabia was used in the current study survey. The statistical results largely support the significant impact of personal interactive benefits, affective benefits, and cognitive benefits, and telepresence on student experience with AR.LRP. Technostress was also found to significantly moderate the relationship between UGT dimensions and student experience with AR.LRP. Further, results support a significant relationship between student experience with AR.LRP and students' learning performance. This study has contributed to the perspectives of researchers and practitioners by highlighting the most important aspects and characteristics that ensure a distinctive and positive students' experience of the drum with applications with AR.LRP.","Title: Analysis of challenges for blockchain adoption within the Indian public sector: an interpretive structural modelling approach\nYear: 2022\n\nAbstract: Purpose Blockchain is one of the most significant emerging technologies that is set to transform many aspects of industry and society. However, it has several major technical, social, legal, environmental and ethical complexities that offer significant challenges for mainstream use within the public sector. The coronavirus disease 2019 (COVID-19) pandemic has compelled many public sector employees to work remotely, highlighting a number of challenges to blockchain adoption within the Indian context signifying the pertinence of this research topic in the post-pandemic era. This study offers insight to researchers and policymakers alike on how such challenges are interdependent within this important subject. Design/methodology/approach We explored 16 unique sets of challenges selected from the literature and gathered data from nine experts from government settings, healthcare and education sectors and academia who have significant knowledge and experience of blockchain implementation and use in their respective organisations. The implementation of Interpretive Structural Modelling (ISM) and Matriced' Impacts Croise's Multiplication Appliquee a UN Classement (MICMAC) provided a precise set of driving, linkage and dependent challenges that were used to formulate the framework. Findings The developed ISM framework is split into six different levels. The results suggest that the bottom level consists of challenges such as \"Lack of standards (C9)\" and \"Lack of validation (C10)\" form the foundation of the hierarchical structure of blockchain adoption. However, the topmost level consists of a highly dependent challenge termed \"adoption of blockchain in the public sector (C16)\". The research filters the selected set of five challenges to develop a parsimonious model and formulated six propositions to examine the impact of \"lack of standard (C9)\", \"lack of validation (C10)\" on \"security issues (C3)\" and \"privacy concerns (C2)\", which eventually determine individuals' \"reluctance to use blockchain technology (C12)\". Originality/value This research fills a key gap in exiting research by exploring the key challenges in blockchain adoption within the public sector by developing a valuable framework to model this important topic. To the best of our knowledge, this is the first paper to address these challenges and develop a parsimonious model for challenges of blockchain adoption in the public sector settings.","Title: Indian Travellers’ Adoption of Airbnb Platform\nYear: 2022\n\nAbstract: Much of the existing scholarly debate on sharing economy to date has focused on the use of technology in developed countries. However, the recent upsurge of mobile technology adoption in developing countries has provided suitable breeding ground for sharing economy. The lack of native theories in tourism and hospitality sector with scare utilization of unified theory of acceptance and use of technology (UTAUT) provide necessity for this research. This study adapted meta-UTAUT model as theoretical lens and extended the model with hedonic motivation, trust, and self-efficacy. Based on data from 301 potential Indian consumers, the results underscored the central role of attitude that significantly mediated the effects of effort expectancy, social influence, and facilitating conditions on consumer intention to use Airbnb. Meanwhile, performance expectancy emerged as significant direct determinant of intention alongside attitude, trust, and self-efficacy. The proposed model explained as much as 65% variance on Indian consumer’s intention to use Airbnb.","Title: Climate change and COP26: Are digital technologies and information management part of the problem or the solution? An editorial reflection and call to action\nYear: 2022\n\nAbstract: The UN COP26 2021 conference on climate change offers the chance for world leaders to take action and make urgent and meaningful commitments to reducing emissions and limit global temperatures to 1.5 °C above pre-industrial levels by 2050. Whilst the political aspects and subsequent ramifications of these fundamental and critical decisions cannot be underestimated, there exists a technical perspective where digital and IS technology has a role to play in the monitoring of potential solutions, but also an integral element of climate change solutions. We explore these aspects in this editorial article, offering a comprehensive opinion based insight to a multitude of diverse viewpoints that look at the many challenges through a technology lens. It is widely recognized that technology in all its forms, is an important and integral element of the solution, but industry and wider society also view technology as being part of the problem. Increasingly, researchers are referencing the importance of responsible digitalization to eliminate the significant levels of e-waste. The reality is that technology is an integral component of the global efforts to get to net zero, however, its adoption requires pragmatic tradeoffs as we transition from current behaviors to a more climate friendly society.","Title: Attention-Based LSTM Network for Rumor Veracity Estimation of Tweets\nYear: 2022\n\nAbstract: Twitter has become a fertile place for rumors, as information can spread to a large number of people immediately. Rumors can mislead public opinion, weaken social order, decrease the legitimacy of government, and lead to a significant threat to social stability. Therefore, timely detection and debunking rumor are urgently needed. In this work, we proposed an Attention-based Long-Short Term Memory (LSTM) network that uses tweet text with thirteen different linguistic and user features to distinguish rumor and non-rumor tweets. The performance of the proposed Attention-based LSTM model is compared with several conventional machine and deep learning models. The proposed Attention-based LSTM model achieved an F1-score of 0.88 in classifying rumor and non-rumor tweets, which is better than the state-of-the-art results. The proposed system can reduce the impact of rumors on society and weaken the loss of life, money, and build the firm trust of users with social media platforms.","Title: Assessing Consumers’ Co‐production and Future Participation On Value Co‐creation and Business Benefit: an F-P-C-B Model Perspective\nYear: 2022\n\nAbstract: Co-production and active participation of the consumers are considered to have enhanced the value co-creation activities that would ensure business benefits of a firm. The marketing literature available does not explicitly explain the philosophy that would motivate the consumers to help to increase values for co-creation activities. In this context, attempts have been made to identify the factors that would impact on co-production and consumers’ participation to co-create values. By studying literature and theories such as theory of co-creation, theory of value creation, information processing theory, marketing theory and expectancy value theory, a conceptual model called F-P-C-B (Future Participation (F) - Co-production (P) - Co-creation (C) - Business Benefit (B)) has been developed along with nine hypotheses. The data was from 362 respondents in India and the model was tested using PLS based analysis. The study shows that it is important for the firms to shift from product-oriented activities to customer-related strategies. It is also found that for obtaining more profitability and better business results, customers should be involved in business activities by way of involving in co-design, idea generation, and other relevant activities of the firms. Moreover, the study highlights that knowledge sharing between the customers and the firm authorities ensures better business values.","Title: Understanding the drivers of online trust and intention to buy on a website: An emerging market perspective\nYear: 2022\n\nAbstract: In recent years, examining the determinants and outcomes of online trust in emerging online markets in the North Africa Region has been lacking. Therefore, the purpose of this study is twofold: first, to gain knowledge of the key predictors of online trust in Morocco; second, to investigate the consequences of online trust on perceived risk, attitude, and online purchase intentions in Morocco. A research model based on the work of Jarvenpaa et al. (2000) was empirically tested. Data was collected from a total of 414 experienced online buyers through online surveys. The PLS approach using SmartPLS 3 was performed to test the hypotheses. The results demonstrate that the effect of perceived size and perceived reputation on online trust is positively significant; online trust has a significant positive influence on attitude and significant negative influence on perceived risk; online trust and attitude positively influence purchase intention; perceived risk has a significant negative effect on attitude and the negative influence of perceived risk on purchase intentions was found to be not significant. The post-hoc analysis further shows that attitude transmits completely the effect of perceived risk on purchase intention, while perceived risk partially mediates the effects of online trust on attitude.","Title: Artificial Intelligence for data-driven decision-making and governance in public affairs\nYear: 2022\n\nAbstract: Literature shows there is a growing interest in studies involving Artificial Intelligence (AI) in the public sector; and while there is evidence of many governmental initiatives that have been established to harness the power of AI, empirical research on the topic and evidence-based insights are rather lacking. The aim of this Special Issue on Artificial Intelligence for Data-Driven Decision-Making and Governance in Public Affairs is to extend both the theoretical and practical boundaries of AI research in the public sector in order to improve governmental decision-making and governance, thus enhancing public value creation. The papers in this special issue focus on AI risks and guidelines, AI governance, the risks of governmental implementation of AI to citizens' privacy, increasing citizen satisfaction through AI-enabled government services, the enablers and challenges of AI implementation in specific public sectors, and using AI to study political opinion. These papers not only advance our knowledge and understanding of the use of AI in government and public governance, but they also help to set out a renewed research agenda. Future research should, among other things, focus on inter- and multi-disciplinary empirical studies that call for the collaboration of a variety of stakeholders; on the longitudinal dynamics of creating public value through the breadth and depth of AI assimilation; and on the investigation of the ethical challenges (particularly data privacy) in AI implementation.","Title: Predicting ratings of social media feeds: combining latent-factors and emotional aspects for improving performance of different classifiers\nYear: 2022\n\nAbstract: Purpose The widespread acceptance of various social platforms has increased the number of users posting about various services based on their experiences about the services. Finding out the intended ratings of social media (SM) posts is important for both organizations and prospective users since these posts can help in capturing the user's perspectives. However, unlike merchant websites, the SM posts related to the service-experience cannot be rated unless explicitly mentioned in the comments. Additionally, predicting ratings can also help to build a database using recent comments for testing recommender algorithms in various scenarios. Design/methodology/approach In this study, the authors have predicted the ratings of SM posts using linear (Naive Bayes, max-entropy) and non-linear (k-nearest neighbor, k-NN) classifiers utilizing combinations of different features, sentiment scores and emotion scores. Findings Overall, the results of this study reveal that the non-linear classifier (k-NN classifier) performed better than the linear classifiers (Naive Bayes, Max-entropy classifier). Results also show an improvement of performance where the classifier was combined with sentiment and emotion scores. Introduction of the feature \"factors of importance\" or \"the latent factors\" also show an improvement of the classifier performance. Originality/value This study provides a new avenue of predicting ratings of SM feeds by the use of machine learning algorithms along with a combination of different features like emotional aspects and latent factors."],"string":"[\n \"Title: Diversity and diffusion of theories, models, and theoretical constructs in egovernment research\\nYear: 2011\\n\\nAbstract: After more than a decade of research in the field of e-government, it is now timely and appropriate to reflect upon the overall developmental directions in the area. The purpose of this paper is to explore research progress to date by systematically analysing the existing body of knowledge on egovernment related issues. Usable data relating to e-government research currently available were collected from 434 research articles. Based on the investigation of the various studies, our findings reveal that survey was the most utilised research method, and the Technology Acceptance Model was the most utilised theory to explain research models. Although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their exploitation by e-government researchers appears largely random in approach. The paper also presents limitations and further research directions.\",\n \"Title: Evaluating The Validity Of Is Success Models For The Electronic Government Research: An Empirical Test And Integrated Model\\nYear: 2013\\n\\nAbstract: The purpose of this paper is to compare and evaluate the validity of Information systems (IS) success models such as DeLone and McLean's (1992), Seddon's (1997), and DeLone and McLean's (2003) IS success models for an e-government application called the Online Public Grievance Redressal System (OPGRS) in context of India. The paper also provides an integrated model of IS success based on the comparison of the three well-known IS success models. All the existing models of IS success are not considered in their original shapes as this research is not using the variables such as use, individual impact, organizational impact from DeLone and McLean (1992) IS success model, use and net benefits from DeLone and McLean (2003) IS success model, and other measures of net benefits of IS use including net benefits to individuals, organizations, and society, and expectations about the net benefits of future IS use from Seddon's (1997) IS success model. The proposed model contains the additional constructs relevant to e-government research including complexity, trust, and facilitating conditions and found that the model performs quite satisfactorily as far as the success of the OPGRS system is concerned. The paper also discusses its limitations, provides implications for theory and practice, and proposed future lines of research which will allow the researchers, practitioners, and government to leverage the full potential of the OPGRS system to curb and eradicate corruption and to build a transparent and sanitized society.\",\n \"Title: Reflecting on E-Government Research: Toward a Taxonomy of Theories and Theoretical Constructs\\nYear: 2011\\n\\nAbstract: After more than a decade of research in the field of e-government, it is now timely and appropriate to reflect upon the overall developmental directions in the area. This paper explores research progress to date by systematically analyzing the existing body of knowledge on e-government related issues, and reveal if there is lack of theoretical development and rigor in the area. Usable data relating to e-government research currently available were collected from 779 research articles identified from the ISI Web of Knowledge database, and by manually identifying relevant articles from dedicated journals on electronic government such as Transforming Government: People, Process, and Policy TGPPP, Electronic Government, an International Journal EGIJ, and International Journal of Electronic Government Research IJEGR. Based on the investigation of the various studies, findings reveal that generic e-government applications were explored more than any specific applications, and the technology acceptance model TAM was the most utilized theory to explain research models. Although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their utilization by e-government researchers appears largely random in approach. The paper also presents limitations and further research directions for future researchers.\",\n \"Title: E-government adoption research: an analysis of the employee's perspective\\nYear: 2013\\n\\nAbstract: This paper works toward analysing the employee's perspective of e-government adoption literature. The purpose of this paper is to provide a review of current literature pertaining to electronic government research in order to observe basic trends and highlight promising lines of inquiry. Of an initial search resulting in 448 articles published in between 2000-2011, 134 were found to discuss adoption of e-government services from an employee's perspective and included in our study. Of these 134 articles, 77 reported qualitative research, 52 quantitative, and five reported activity belonging to both categories. The findings suggest that there is currently a relative lack of theoretical development and rigor in the area, and although many aspects such as job relevance, security, perceived benefits, anxiety, and perceived quality are clearly significant as far as employee's adoption is concerned, they have not been investigated to their potential, and there remains much opportunity for researchers to shape and develop the field. Restricting our analysis to theoretical constructs and their frequency may not provide a full picture of the relevance of the constructs.\",\n \"Title: A Meta-Analysis Of The Unified Theory Of Acceptance And Use Of Technology (Utaut)\\nYear: 2011\\n\\nAbstract: The originating article of the Unified Theory of Acceptance and Use of Technology (UTAUT) has been cited by a large number of studies. However, a detailed examination of such citations revealed that only small proportion (43 articles) of these citations actually utilized the theory or its constructs in their empirical research for examining IS/IT related issues. In order to examine whether the theory is performing consistently well across various studies, this research aims to undertake a statistical meta-analysis of findings reported in 43 published studies that have actually utilized UTAUT or its constructs in their empirical research. Findings reveal the underperformance of theory in subsequent studies in comparison to the performance of UTAUT reported in the originating article. The limitations experienced while conducting the metaanalysis, recommendations, and the future scope for the further research in this area have also been briefly explained in concluding section.\",\n \"Title: Investigating success of an e-government initiative: Validation of an integrated IS success model\\nYear: 2015\\n\\nAbstract: The purpose of this paper is to examine the success (by measuring intention to use and user satisfaction) of the online public grievance redressal system (OPGRS) from the perspective of the citizens of India. The success of this e-government system is examined using an integrated IS success model. The model developed includes the constructs such as system quality, information quality, service quality, perceived usefulness, perceived ease of use, perceived satisfaction, perceived risk, and behavioral intention. The proposed integrated research model of IS was validated using the response taken from 419 citizens from different cities of India. The empirical outcomes provided the positive significant connections between all 12 hypothesised relationships between eight constructs. The empirical evidence and discussion presented in the study can help the government to improve upon and fully utilise the potential of the OPGRS as a useful tool toward a transparent and corruption free country.\",\n \"Title: The unified theory of acceptance and use of technology (UTAUT): a literature review.\\nYear: 2015\\n\\nAbstract: Purpose - The purpose of this paper is to perform a systematic review of articles that have used the unified theory of acceptance and use of technology (UTAUT). Design/methodology/approach - The results produced in this research are based on the literature analysis of 174 existing articles on the UTAUT model. This has been performed by collecting data including demographic details, methodological details, limitations, and significance of relationships between the constructs from the available articles based on the UTAUT. Findings - The findings indicated that general purpose systems and specialized business systems were examined in the majority of the articles using the UTAUT. The analysis also indicated that cross-sectional approach, survey methods, and structural equation modelling analysis techniques were the most explored research methodologies whereas SPSS was found to be the largely used analysis tools. Moreover, the weight analysis of independent variables indicates that variables such as performance expectancy and behavioural intention qualified for the best predictor category. Moreover, the analysis also suggested that single subject or biased sample as the most explored limitation across all studies. Research limitations/implications - The search activities were centered on occurrences of keywords to avoid tracing a large number of publications where these keywords might have been used as casual words in the main text. However, we acknowledge that there may be a number of studies, which lack keywords in the title, but still focus upon UTAUT in some form. Originality/value - This is the first research of its type which has extensively examined the literature on the UTAUT and provided the researchers with the accumulative knowledge about the model.\",\n \"Title: Examining the Success of the Online Public Grievance Redressal Systems: An Extension of the IS Success Model\\nYear: 2015\\n\\nAbstract: The purpose of this article is to examine the success of the online public grievance redressal system from the perspective of the citizens of India. The empirical outcomes provided the positive significant connections between all 13 hypothesized relationships among the seven constructs. The empirical evidence and discussion presented in the study can help the Indian government to improve upon and fully utilize the potential of the online public grievance redressal system for transparent and corruption free country.\",\n \"Title: Profiling Existing Research on Social Innovation in the Public Sector\\nYear: 2014\\n\\nAbstract: This study explores the progress of social innovation research in a public sector context by systematically analyzing its existing body of knowledge to identify areas of societal impact and reveal areas of limitations and potential further research. The findings revealed that most of the studies on social innovation in the public sector are conceptual in nature. The article presents propositions based on the diagnosed limitations of research in the area.\",\n \"Title: Can Marketing Strategies Enhance the Adoption of Electronic Government Initiatives?\\nYear: 2014\\n\\nAbstract: This article assesses the role and likely impact of marketing on the adoption of e-government initiatives. Although the role of tactical marketing in increasing awareness and enhancing adoption has been recognised, strategies required for realising the benefits of marketing e-government services have not been forthcoming. Given that citizens' usage behaviour of e-government services remains sub-optimal and the potential contribution of marketing, we propose a set of marketing-based strategic approaches and argue that they can play an essential role in enhancing adoption of e-government initiatives and propelling citizen's engagement with e-governance. Based on citizens' differential levels of usage behaviour of e-government services and benefits sought from engaging in e-governance, this article classifies citizens into six distinct segments and suggests generic strategic approaches.\",\n \"Title: A meta-analysis of existing research on citizen adoption of e-government\\nYear: 2015\\n\\nAbstract: The purpose of this paper is to perform a weight-analysis and to undertake a meta-analysis of findings reported in published research on the adoption and diffusion of e-government. Usable data relating to e-government adoption research were collected from 103 empirical studies. Of those 103 articles, only 63 used a range of different constructs with appropriate correlation values required for performing a weight- and meta-analysis. Diagrammatic representation has been presented using significant as well as non-significant relationships from all 103 publications. A broader analysis of research on adoption and diffusion of e-government also reflects that although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their utilization by e-government researchers appears to be largely random in approach. This paper also acknowledges the theoretical contribution, the limitations of this study, and suggests further research directions for the continued work.\",\n \"Title: Adoption of online public grievance redressal system in India: Toward developing a unified view.\\nYear: 2016\\n\\nAbstract: The aim of this research is to develop a unified model of electronic government (e-government) system adoption and validate it using the data gathered from 419 citizens from few selected cities in India. In course of doing so, the research also evaluates the performance of nine well-known alternative theoretical models of information technology (IT) adoption including the unified theory of acceptance and use of technology (UTAUT). The results indicate that the proposed unified model for e-government adoption by this research has outperformed all other theoretical models by explaining highest 66% variance on behavioral intentions, adequately acceptable levels of fit indices, and significant relationships between each hypothesis. The research also provides its limitations and presents implications for theory and practice toward the end.\",\n \"Title: Consumer adoption of mobile banking in Jordan: Examining the role of usefulness, ease of use, perceived risk and self-efficacy.\\nYear: 2015\\n\\nAbstract: Purpose - The purpose of this paper is to propose and examine a conceptual model that best explains the key factors influencing Jordanian customers' intention to adopt mobile banking (MB). Design/methodology/approach - The proposed conceptual model was based on the Technology Acceptance Model (TAM). This was extended by adding perceived risk and self-efficacy as an external factors. Structural equation modelling (SEM) was conducted to analyse the data collected from the field survey questionnaires administered to a convenience sample of Jordanian banking customers. Findings - The results showed that behavioural intention is significantly influenced by perceived usefulness, perceived ease of use, and perceived risk. Research limitations/implications - Practical and theoretical implications for both Jordanian banks and researchers in the MB context are also discussed in the concluding section. Originality/value - MB-related issues are yet to be examined empirically in the Jordanian context. This submission has attempted to fill this gap by empirically examining some of the important factors influencing the adoption of MB from the Jordanian customers' perspective.\",\n \"Title: Adoption of Mobile Banking in Jordan: Exploring Demographic Differences on Customers' Perceptions.\\nYear: 2015\\n\\nAbstract: This study aims to explore whether Jordanian customers' perceptions on intention and adoption of Mobile banking (MB) services varies according to their demographic characteristics. As per the prior literature, five demographic factors, namely age, gender, income, education and customer's experience with computer and Internet have been considered in the current study. The required data were collected from the field survey questionnaires administered to a convenience sample of Jordanian banking customers. The major statistical results (mean and standard deviation) demonstrate that the customers' perceptions on intention and adoption of MB are likely to vary due to customers' demographic differences. According to the current study's findings, it was also noticed that despite the fact that the most of the sample respondents express a high intention to adopt MB, the adoption rate for the majority of MB services was low.\",\n \"Title: Sentiment Analysis of Products' Reviews Containing English and Hindi Texts.\\nYear: 2015\\n\\nAbstract: The online shopping is increasing rapidly because of its convenience to buy from home and comparing products from their reviews written by other purchasers. When people buy a product, they express their emotions about that product in the form of review. In Indian context, it is found that the reviews contain Hindi text along with English. It is also found that most of the Hindi text contains opinionated words like bahut achha, bakbas, pesa wasool etc. We have tried to find out different Hindi texts appearing in product reviews written on Indian E-commerce portals. We have also developed a system which takes all those reviews containing Hindi as well as English texts and find out the sentiment expressed in that review for each attribute of the product as well as a final review of the product.\",\n \"Title: Driving Innovation Using Big Open Linked Data (BOLD) Panel\\nYear: 2015\\n\\nAbstract: Governments have always retained public service data internally in their own systems with only limited information provided to the public and other stakeholders such as the business, charitable and NGO communities. However, the rapid advancement of ICTs coupled with electronic publishing via the Internet in the last decade in particular has enabled governments to exploit the potential of wider distribution and use of such data previously held in internal systems. The panellists will discuss how Big, Open and Linked Data (BOLD) can be utilized to drive innovation and what obstacles and challenges may be encountered. Empowering citizens, potential mis-use in identity theft, policy manipulation or market distortion, and the need to combine open data with closed sources will be discussed.\",\n \"Title: A MapReduce Based Distributed Framework for Similarity Search in Healthcare Big Data Environment\\nYear: 2015\\n\\nAbstract: Similarity search in the big data environment is a challenging task. Patient Similarity search (PaSi) is an important issue in healthcare network and data. The results of PaSi search may be highly useful for drawing different conclusions and decisions to improve healthcare systems. Such findings can also be useful for choosing the treatment paths for new patients. In this paper, we propose a MapReduce based framework as a solution to the PaSi problem in the context of a healthcare network imagined to be implemented considering the healthcare centers of India. It is assumed that such a healthcare network will be implemented in future over the Government of India cloud known as GI cloud or 'MeghRaj'. The paper also discusses the associated implementation challenges of the proposed framework and the query handling approach for the proposed framework to solve the PaSi problem is stated. Finally, the paper outlines the future scope of the work.\",\n \"Title: Citizen's Adoption of an E-Government System: Validating the Extended Theory of Reasoned Action TRA\\nYear: 2015\\n\\nAbstract: AbstractThe study explores the adoption of an electronic government e-government system called online PAN card registration system OPCRS in context of India. The study validates the extended theory of reasoned action TRA to understand the impact of some of its factors on the citizen's intention to adopt this system. The proposed research model is extended with the variables including perceived usefulness, perceived trust, and self-efficacy as antecedents of attitude and subjective norm, which are the core constructs of the TRA. The eight hypotheses were formulated between six constructs of the proposed extended TRA. The proposed research model is validated using the usable sample of data gathered from 377 respondents. The data was analysed using AMOS 22.0. The empirical findings of the proposed research model indicated the significant relationships of all proposed hypotheses. The study also provides its limitations, future research directions, and implications for theory and practice toward the end.\",\n \"Title: An Empirical Study of Facebook Adoption Among Young Adults in a Northeastern State of India: Validation of Extended Technology Acceptance Model (TAM).\\nYear: 2016\\n\\nAbstract: The purpose of this paper is to explore the adoption of a social networking site called Facebook in context of a landlocked and one of the least populous states in India. The adoption of Facebook is examined by considering technology acceptance model (TAM) as a basic model along with additional constructs such as subjective norm and perceived trust in it. The data were collected from 202 young adults from couple of degree level colleges from one of the least populous and landlocked states called Sikkim in India. The empirical outcomes provided the positive significant connections between nine hypothesised relationships among seven constructs. The article also discusses the resulting theoretical contributions for Facebook adoption and discusses practical implications of Facebook adoption for Facebook providers and users.\",\n \"Title: A Systematic Review of Extant Literature in Social Media in the Marketing Perspective.\\nYear: 2016\\n\\nAbstract: Social media applications have been extensively used and adopted by individuals and organisations in most aspects of daily life. Likewise, researchers have spent much effort in examining and exploring the effectiveness and efficiency of engaging such applications over the marketing context. This study, therefore, realizes the necessity of conducting a review of prior literature of social media over the marketing context especially in the light of the fact that only a small number of studies have been reviewed and conducted in this area. Accordingly, the aim of this study is to systematically review the current literature of social media in the marketing context. By reviewing approximately 71 articles, this study provides an overview of the main themes and trends covered by the relevant literature such as the role of social media on advertising, the electronic word of mouth, customers' relationship management, and firms' brands and performance.\",\n \"Title: The changing landscape of IS project failure: an examination of the key factors.\\nYear: 2017\\n\\nAbstract: Purpose - Information systems (IS) project failure has been a recurring problem for decades. The purpose of this paper is twofold: first, to examine the key factors that influence project failure and an analysis of the major areas that can have a significant impact on success; and second, to explore some of the key aspects that have an impact on project management performance from the practitioner perspective and discusses the problems faced by organizations in the closer integration of change and project management. Design/methodology/approach - This study critically reviews the IS failure literature developing a synthesized view of the key issues and common reasons for projects to fail. The approach taken in this study is one that focuses on a number of key questions that pull together the relevant themes in this genre of research whilst highlighting many of the implications for practitioners and organizations alike. Findings - Key questions remain on the underlying causes of instances of poor project management as an IS failure factor. The literature has omitted to develop a deeper analysis of the associations between failure factors and the potential causal relationships between these factors. The realization of project benefits relies on the success of both change and project management yet the formal integration of these two disciplines is constrained by separate standards bodies and an immature body of research. Research limitations/implications - This study is limited by its theoretical nature lacking an empirical element to provide a deeper analysis of IS failure factors and their interrelationships. This specific area is a recommendation for future research, where causal relationships between failure factors could be developed via a mathematic-based method such as interpretive structural modeling. Practical implications - With failure rates of IS projects still unacceptably high after decades of attempts to significantly change outcomes, a deeper analysis of this topic is required. The research gaps and recommendations for practitioners highlighted in this study have the potential to provide valuable contributions to this topic of research. Originality/value - The intent of this study is to present a new perspective of this genre of IS research that develops the main arguments and gaps in the literature from the practitioner viewpoint.\",\n \"Title: Driving innovation through big open linked data (BOLD): Exploring antecedents using interpretive structural modelling.\\nYear: 2017\\n\\nAbstract: Innovation is vital to find new solutions to problems, increase quality, and improve profitability. Big open linked data (BOLD) is a fledgling and rapidly evolving field that creates new opportunities for innovation. However, none of the existing literature has yet considered the interrelationships between antecedents of innovation through BOLD. This research contributes to knowledge building through utilising interpretive structural modelling to organise nineteen factors linked to innovation using BOLD identified by experts in the field. The findings show that almost all the variables fall within the linkage cluster, thus having high driving and dependence powers, demonstrating the volatility of the process. It was also found that technical infrastructure, data quality, and external pressure form the fundamental foundations for innovation through BOLD. Deriving a framework to encourage and manage innovation through BOLD offers important theoretical and practical contributions.\",\n \"Title: Authenticity Of Geo-Location And Place Name In Tweets\\nYear: 2017\\n\\nAbstract: The place name and geo-coordinates of tweets are supposed to represent the possible location of the user at the time of posting that tweet. However, our analysis over a large collection of tweets indicates that these fields may not give the correct location of the user at the time of posting that tweet. Our investigation reveals that the tweets posted through third party applications such as Instagram or Swarmapp contain the geo-coordinate of the user specified location, not his current location. Any place name can be entered by a user to be displayed on a tweet. It may not be same as his/her exact location. Our analysis revealed that around 12% of tweets contains place names which are different from their real location. The findings of this research can be used as caution while designing location-based services using social media.\",\n \"Title: User Adoption Of Cashless Services In Indian Context - A Preliminary Analysis\\nYear: 2017\\n\\nAbstract: The recent measures adopted by the Government of India for the financial reforms in the country has led to an urgent need of different modes for cashless services. India is a country of diverse culture inhabited by people having a wide range of demographic factors. It is, thus, essential to identify the significant factors that affect the individual's intention to adopt the cashless services. The main objective of this research is to analyse the users' behaviour towards several constructs that have been identified as the potential enablers of the high rate of adoption of cashless services in India. The study builds upon the Unified Theory of Acceptance and Use of Technology model and adds several new factors that are significant in the Indian context. Results obtained through descriptive statistics suggest that the identified constructs are perceived significant by the users in shaping their intentions towards the use of cashless services.\",\n \"Title: Assessing Consumers' Intention To Adopt Mobile Internet Services In The Kingdom Of Saudi Arabia\\nYear: 2017\\n\\nAbstract: This study was conducted with intention to provide a further understanding about the most predictive factors that could shape the customers' intention to adopt Mobile Internet services in the Kingdom of Saudi Arabia. Thus, and according to critical reviewing of the main body of literature over the relevant area, researchers were able to identify four main factors that could have impact on the behavioural intention. These factors are performance expectancy, effort expectancy, hedonic motivation, and awareness that all are proposed in the same conceptual model of the current study. The current study data was collected from three main cities in Saudi Arabia (Jeddah, Riyadh and Dammam). Then structural equation modelling using AMOS was adopted to examine the proposed model and verify the research hypotheses. Statistical results largely supported the factors included as all of these factors have a significant influence on the customers' intention to adopt Mobile Internet services. Hopefully, such results will provide accurate clues for designers and practitioners to focus more on the most important aspects that attract attention from customers in the Kingdom of Saudi Arabia.\",\n \"Title: Exploring the Role of Social Media in e-Government: an Analysis of Emerging Literature\\nYear: 2017\\n\\nAbstract: Driven by rising citizen expectations and the need for government innovation, social media has become a key component of e-government in a very short period of time. A number of research papers have been published on the role of social media in e-government in last few years. This study performs a literature review of the articles on the use of social media for getting access to e-government websites from the perspective of citizens. The database search through Scopus resulted in 115 articles, which formed the basis of this literature review. The keywords analysis of these articles indicates that 'e-government' and 'social media' were the most explored keywords across these studies. The methodological analysis indicates that the majority of the studies were analytical/conceptual/descriptive/theoretical in nature. The theoretical analysis, however, indicates that there is a lack of such research that has used some well-established theories or models to understand this concept. The review of literature further indicates that research themes such as 'electronic participation', 'engagement', 'transparency', 'communication/ interaction', 'trust' and 'collaboration' were found as some of the most frequently used categories under this area of research.\",\n \"Title: A Systematic Review of Citations of UTAUT2 Article and Its Usage Trends.\\nYear: 2017\\n\\nAbstract: Unified Theory of Acceptance and Use of Technology (UTAUT) is considered as the most comprehensive theory in Information Systems (IS) research to understand technology acceptance across various use contexts. The theory was extended to consumer context by incorporating three external constructs. This extended version is referred as UTAUT2. Although UTAUT2 is relatively new, the increasing number of citations is a testimony to the fact that it’s popular amongst IS researchers especially for examining consumer- focused issues. However, none of the existing studies attempted to analyze the pattern of UTAUT2 citations. This study is aimed to undertake a systematic review of 650 citations with a motivation to fulfill this research gap. The study revealed that majority of the studies i.e. 77% cited UTAUT2 for general citation purpose. However, the remaining 23%, even if they utilized UTATU2, did so in combination with external theories where the moderators of UTAUT2 were rarely considered.\",\n \"Title: Advances in Electronic Government (e-Government) Adoption Research in SAARC Countries.\\nYear: 2017\\n\\nAbstract: This paper profiles the research activities that have been published on e-government adoption in the context of South Asian Association for Regional Cooperation (SAARC) countries. Our analysis includes variables such as the years of publication, journals most often publishing papers on e-government adoption, countries in which the research activity was conducted, the authors most active in the subject area, keywords analysis, methodological analysis, technology and respondents contexts, analysis of theories or models used and analysis of limitations and future research directions extracted from 48 research papers that were extracted from Scopus database using some key terminologies related to e-government, adoption and eight SAARC countries. This is the first study that has comprehensively examined the analysis of e-government adoption literature in these eight countries’ context. The results of this research provide some promising lines of inquiry that have been largely neglected along with those that have received a much larger attention.\",\n \"Title: An empirical validation of a unified model of electronic government adoption (UMEGA).\\nYear: 2017\\n\\nAbstract: In electronic government (hereafter e-government), a large variety of technology adoption models are employed, which make researchers and policymakers puzzled about which one to use. In this research, nine well-known theoretical models of information technology adoption are evaluated and 29 different constructs are identified. A unified model of e-government adoption (UMEGA) is developed and validated using data gathered from 377 respondents from seven selected cities in India. The results indicate that the proposed unified model outperforms all other theoretical models, explaining the highest variance on behavioral intention, acceptable levels of fit indices, and significant relationships for each of the seven hypotheses. The UMEGA is a parsimonious model based on the e-government-specific context, whereas the constructs from the original technology adoption models were found to be inappropriate for the e-government context. By using the UMEGA, relevant e-government constructs were included. For further research, we recommend the development of e-government-specific scales.\",\n \"Title: Social media in marketing: A review and analysis of the existing literature.\\nYear: 2017\\n\\nAbstract: •A growing number of research studies have addressed the issues of social media in marketing.•This research reviewed 144 studies on social media in marketing context.•Seven key themes emerged from the literature.•Promotional and advertising efforts, e-WOM and CRM are some prominent themes.•Facebook has been the most frequently used social media platform examined.\",\n \"Title: Use of Social Media in Citizen-Centric Electronic Government Services: A Literature Analysis\\nYear: 2017\\n\\nAbstract: AbstractThis article undertakes a literature review on such articles on social media and citizen-centric e-government services. This research uses 139 articles to perform the intended literature review. The keywords analysis of these articles indicates that Web 2.0, participation and open government/open data were some of the frequently used keywords in addition to the two major themes of e-government and social media on which all the articles were searched for. The analysis of research methods indicated that majority of the studies were analytical, conceptual, descriptive, or theoretical in nature. The theoretical analysis however indicated that there is a lack of theory-based research in this area. The review of literature indicated that research themes such as electronic participation, engagement, transparency, communication/interaction, trust, security and collaboration are some of the most frequently used categories under this area of research. A research framework has also been proposed from the key themes emerging from the review.\",\n \"Title: An empirical examination of antecedents determining students' usage of clickers in a digital marketing module.\\nYear: 2018\\n\\nAbstract: As more and more educational institutions are integrating new technology such as clickers into their learning system, it becomes increasingly essential to have an understanding of studentsu0027 perceptions about such technology on their overall learning process. The incorporation of clickers into teaching instructions has created implications for teaching practices and student satisfaction. The purpose of this research is to understand student use and satisfaction with clickers in a large undergraduate digital marketing class in a British university. To do so, we propose a conceptual model based on information systems (IS) success models to understand studentu0027s usage behaviour and satisfaction with clickers. The data were analysed based on 138 valid responses gathered from the students, where clickers are effectively used for teaching and learning purposes. The results provided a strong support for all eight hypothesised relationships and adequate variance on its key dependent variables in the proposed resear...\",\n \"Title: The Impact of Social Media on Consumers' Acculturation and Purchase Intentions.\\nYear: 2018\\n\\nAbstract: Social media has emerged as a significant and effective means of assisting and endorsing activities and communications among peers, consumers and organizations that outdo the restrictions of time and space. While the previous studies acknowledge the role of agents of culture change, it largely remains silent on the role of social media in influencing acculturation outcomes and consumption choices. This study uses self-administered questionnaire to collect data from 514 Turkish-Dutch respondents and examines how their use of social media affects their acculturation and consumption choices. This research makes a significant contribution to consumer acculturation research by showing that social media is a vital means of culture change and a driver of acculturation strategies and consumption choices. This study is the first to investigate the role of social media as an agent of culture change in terms of how it impacts acculturation and consumption. The paper discusses implications for theory development and for practice.\",\n \"Title: Advances in Social Media Research: Past, Present and Future.\\nYear: 2018\\n\\nAbstract: Social media comprises communication websites that facilitate relationship forming between users from diverse backgrounds, resulting in a rich social structure. User generated content encourages inquiry and decision-making. Given the relevance of social media to various stakeholders, it has received significant attention from researchers of various fields, including information systems. There exists no comprehensive review that integrates and synthesises the findings of literature on social media. This study discusses the findings of 132 papers (in selected IS journals) on social media and social networking published between 1997 and 2017. Most papers reviewed here examine the behavioural side of social media, investigate the aspect of reviews and recommendations, and study its integration for organizational purposes. Furthermore, many studies have investigated the viability of online communities/social media as a marketing medium, while others have explored various aspects of social media, including the risks associated with its use, the value that it creates, and the negative stigma attached to it within workplaces. The use of social media for information sharing during critical events as well as for seeking and/or rendering help has also been investigated in prior research. Other contexts include political and public administration, and the comparison between traditional and social media. Overall, our study identifies multiple emergent themes in the existing corpus, thereby furthering our understanding of advances in social media research. The integrated view of the extant literature that our study presents can help avoid duplication by future researchers, whilst offering fruitful lines of enquiry to help shape research for this emerging field.\",\n \"Title: understanding 'development' from the perspective of e-government, digital divide and ICT4D literature: a research agenda.\\nYear: 2018\\n\\nAbstract: This paper asserts that considering the growing importance and significance of e-Government initiatives around the world and the increasing priority it has on governmentsu0027 agendas and investment costs, a more comprehensive understanding of u0027developmentu0027 is needed to complement what we already know about e-Government initiatives. This submission makes the case for why the issue of u0027developmentu0027 should be studied in more detail in e-Government research and aims to clarify the conceptualization and understanding of u0027developmentu0027 as it pertains to the use of ICTs in the digital government domain, drawing upon literature in two related research domains: Digital Divide and ICT for Development (ICT4D). E-Government research currently cuts short at understanding factors that affect the adoption and implementation of e-Government initiatives and tends to converse around the concept of u0027developmentu0027 at a general level. The literature in Digital Divide and ICT4D overcomes some of the perceived shortcomings of the e-Government literature, largely the issue of development in relation to citizens and the importance of considering context in more detail. By undertaking research using a case study approach within the UK and Tanzania, the proposed study will help to understand the impact of e-Government initiatives on citizensu0027 development and what this actually means over a longer period of time beyond the implementation stage. Such understanding is important to ensure that the very goals of e-Government initiatives are realised in relation to the context in which initiatives are deployed. By understanding from the e-Government perspective what development equates to and how it could possibly be measured can help in the design and rollout of future initiatives and can be considered to be positive steps towards achieving the UNu0027s Millennium Development Goals.\",\n \"Title: Ranking online consumer reviews.\\nYear: 2019\\n\\nAbstract: •A regression prediction model is proposed to rank the reviews based on their quality.•Results reveal that training the model only on high quality reviews performed better.•We use two new features product description data and customer question answer data.\",\n \"Title: Citizens' Awareness, Acceptance and Use of Mobile Government Services in India: An Exploratory Research.\\nYear: 2018\\n\\nAbstract: The development of mobile technology is not only changing the way business is run, as evidenced by the fast growth of mobile commerce, but also facilitating the transformation in a way that governments deliver their services. Mobile government is one area that has received very little research, but it can have a tremendous impact on the way citizens engage with their government. This research will analyse the data gathered from 25 respondents through online survey on the various aspects of mobile government and in India and their views on some of the key questions related to the use of mobile government in the country.\",\n \"Title: Identifying reputation collectors in community question answering (CQA) sites: Exploring the dark side of social media.\\nYear: 2018\\n\\nAbstract: •The paper identifies users who post and motivate others to post low quality and duplicate contents on CQA sites.•The good guys are called Caretakers and bad guys are considered as Reputation Collectors.•A graph based methodology was employed to derive the characteristic of Reputation Collectors and Caretakers.•The algorithms have been developed to identify the Reputation Collectors and Caretakers.•The results indicate that 1.05% of Reputation Collectors post 18.88% of low-quality answers.\",\n \"Title: Factors influencing e-diplomacy implementation: Exploring causal relationships using interpretive structural modelling.\\nYear: 2018\\n\\nAbstract: Electronic diplomacy (E-diplomacy) is the use of technology by nations to define and establish diplomatic goals and objectives and to efficiently carry out the functions of diplomats. These functions include representation and promotion of the home nation, establishing both bilateral and multilateral relations, consular services and social engagement. It encapsulates the adoption of multiple ICT tools over the Internet to support a nation's interests in other countries while ensuring that foreign relations are improved between the countries. Given its embryonic nature, little scholarly research has been undertaken to study its influence on diplomatic functions and the various factors that influence its implementation. This paper applies the Interpretative Structural Modelling (ISM) methodological approach to identify factors that impact the implementation of e-diplomacy and to determine their causal relationship and rankings. This study applies the ISM methodology to the subject of e-diplomacy. The ISM-based model provides a framework for practitioners to aid decision-making and manage the implementation of e-diplomacy.\",\n \"Title: Exploring barriers of m-commerce adoption in SMEs in the UK: Developing a framework using ISM.\\nYear: 2019\\n\\nAbstract: •The concept of m-commerce has grown exponentially within business in the last decade.•The paper aims to understand barriers of m-commerce adoption in SMEs in Wales.•The paper used Interpretive Structural Modelling and MICMAC to develop a framework.•A large number of the barriers of m-commerce adoption have high levels of driving power.•The findings indicated perceived risk as the key driving barrier of m-commerce adoption.•The lack of customer trust and confidence depends the most on all other variables.\",\n \"Title: Consumer use of mobile banking (M-Banking) in Saudi Arabia: Towards an integrated model.\\nYear: 2019\\n\\nAbstract: •M-Banking is one of the most promising technologies that could prove to have considerable value to both banks and customers.•This study investigates factors that could predict the use of M-Banking, customer satisfaction and customer loyalty.•This study proposes a comprehensive conceptual model that clarifies the use of M-Banking from the perspective of Saudi users.•A questionnaire survey was conducted to collect the required data from convenience sampling of Saudi bank customers.•This study would consider the adoption of numeric data in order to inferentially analyse them using SEM.\",\n \"Title: Mobile applications in government services (mG-App) from user's perspectives: A predictive modelling approach.\\nYear: 2018\\n\\nAbstract: Mobile applications are becoming a preferred delivery method for the government sector and contributing to more convenient and timely services to citizens. This study examines the intention to use mobile applications for the government services (mG-App) in Oman. This study extended the Unified Theory of Acceptance and Use of Technology (UTAUT) model by including two constructs namely trust and information quality. Data were collected from 513 mobile application users across Oman. The research model was analysed in two stages. First, structural equation modelling (SEM) was employed to determine significant determinants affecting users' acceptance of mG-App. In the second stage, a neural network model was used to validate SEM results and determine the relative importance of determinants of acceptance of mG-App. The findings revealed that trust and performance expectancy are the strongest determinants influencing the acceptance of mG-App. The findings of this research have provided theoretical contributions to the existing research on mG-App and practical implications to decision-makers involved in the development and implementation of mG-App in in Oman.\",\n \"Title: Re-examining the Unified Theory of Acceptance and Use of Technology (UTAUT): Towards a Revised Theoretical Model\\nYear: 2019\\n\\nAbstract: Based on a critical review of the Unified Theory of Acceptance and Use of Technology (UTAUT), this study first formalized an alternative theoretical model for explaining the acceptance and use of information system (IS) and information technology (IT) innovations. The revised theoretical model was then empirically examined using a combination of meta-analysis and structural equation modelling (MASEM) techniques. The meta-analysis was based on 1600 observations on 21 relationships coded from 162 prior studies on IS/IT acceptance and use. The SEM analysis showed that attitude: was central to behavioural intentions and usage behaviours, partially mediated the effects of exogenous constructs on behavioural intentions, and had a direct influence on usage behaviours. A number of implications for theory and practice are derived based on the findings.\",\n \"Title: Barriers to the Development of Smart Cities in Indian Context\\nYear: 2019\\n\\nAbstract: Smart city development is gaining considerable recognition in the systematic literature and international policies throughout the world. The study aims to identify the key barriers of smart cities from a review of existing literature and views of experts in this area. This work further makes an attempt on the prioritisation of barriers to recognise the most important barrier category and ranking of specific barriers within the categories to the development of smart cities in India. Through the existing literature, this work explored 31 barriers of smart cities development and divided them into six categories. This research work employed fuzzy Analytic Hierarchy Process (AHP) technique to prioritise the selected barriers. Findings reveal that ‘Governance’ is documented as the most significant category of barriers for smart city development followed by ‘Economic; ‘Technology’; ‘Social’; ‘Environmental’ and ‘Legal and Ethical’. In this work, authors also performed sensitivity analysis to validate the findings of study. This research is useful to the government and policymakers for eradicating the potential interferences in smart city development initiatives in developing countries like India.\",\n \"Title: Event classification and location prediction from tweets during disasters\\nYear: 2019\\n\\nAbstract: Social media is a platform to express one’s view in real time. This real time nature of social media makes it an attractive tool for disaster management, as both victims and officials can put their problems and solutions at the same place in real time. We investigate the Twitter post in a flood related disaster and propose an algorithm to identify victims asking for help. The developed system takes tweets as inputs and categorizes them into high or low priority tweets. User location of high priority tweets with no location information is predicted based on historical locations of the users using the Markov model. The system is working well, with its classification accuracy of 81%, and location prediction accuracy of 87%. The present system can be extended for use in other natural disaster situations, such as earthquake, tsunami, etc., as well as man-made disasters such as riots, terrorist attacks etc. The present system is first of its kind, aimed at helping victims during disasters based on their tweets.\",\n \"Title: Involvement In Emergency Supply Chain For Disaster Management: A Cognitive Dissonance Perspective\\nYear: 2018\\n\\nAbstract: An integrated process, interlinked operation and interoperable communication network amongst operating agencies are critical for developing an effective disaster management supply chain. The traditional managerial problems observed across disaster management operations are: non-cooperation among members, disrupted chain of commands, misuse of relief items, lack of information sharing, mistrust and lack of coordination. This study aims to understand the issues affiliated with negative attitude towards disaster management operations using theory of cognitive dissonance. A qualitative investigation was undertaken across 64 districts in Bangladesh. Five constructs were examined for their influences on attitude and behavioural intention of members participating in government emergency supply chain for disaster management. The results indicate that administrative conflict, political biasness and professional growth have significant effects on attitude. Impact of insecurity is non-significant on attitude. This research offers substantial theoretical contribution to the cognitive dissonance theory in the context of disaster management supply chain.\",\n \"Title: Impact of internet of things (IoT) in disaster management: a task-technology fit perspective\\nYear: 2019\\n\\nAbstract: Disaster management aims to mitigate the potential damage from the disasters, ensure immediate and suitable assistance to the victims, and attain effective and rapid recovery. These objectives require a planned and effective rescue operation post such disasters. Different types of information about the impact of the disaster are, hence, required for planning an effective and immediate relief operation. The IoT technology available today is quite mature and has the potential to be very useful in disaster situations. This paper analyzes the requirements for planning rescue operation for such natural disasters and proposes an IoT based solution to cater the identified requirements. The proposed solution is further validated using the task-technology fit (TTF) approach for analyzing the significance of the adoption of IoT technology for disaster management. Results from the exploratory study established the core dimensions of the task requirements and the TTF constructs. Results from the confirmatory factor analysis using PLS path modelling, further, suggest that both task requirements and IoT technology have significant impact on the IoT TTF in the disaster management scenario. This paper makes significant contributions in the development of appropriate constructs for modeling TTF for IoT Technology in the context of disaster management.\",\n \"Title: Predicting changing pattern: building model for consumer decision making in digital market.\\nYear: 2018\\n\\nAbstract: Purpose - Consumers have the multiple options to choose their products and services, which have a significant impact on the pattern of consumer decision making in digital market and further increases the challenges for the service providers to predict their buying pattern. In this sense, the purpose of this paper is to propose a structural hierarchy model for analyzing the changing pattern of consumer decision making in digital market by taking an Indian context. Design/methodology/approach - To accomplish the objectives, the research is conducted in two phases. An extensive literature review is performed in the first phase to list the factors related to the changing pattern of consumer decision making in digital market and then fuzzy Delphi method is applied to finalize the factors. In the second phase, fuzzy analytic hierarchy process (AHP) is employed to find the priority weights of finalized factors. The fuzzy set theory allows capturing the vagueness in the data. Findings - The findings obtained in this study shows that consumers are much conscious about innovative and trendy products as well as brand and quality; therefore, the service providers must think about these two most important factors so that they can able to retain their consumer in their online portal. Practical implications - The analysis shows that \\\"innovative and trendy\\\" is the first priority factor for the consumers followed by \\\"brand and quality\\\" and \\\"fulfilment and time energy.\\\" The proposed model can help the marketers and service providers in predicting customers' preferences and their changing pattern efficiently under vague surroundings. The outcomes of this research work not only help the service provider to update their products and services according to consumers' needs but can also help them to increase profit and minimize their risk. Originality/value - This work contributes to consumer research literature focusing on problem evaluation in the context of changing pattern of consumer decision making in digital era.\",\n \"Title: Using privacy calculus theory to explore entrepreneurial directions in mobile location-based advertising: Identifying intrusiveness as the critical risk factor\\nYear: 2019\\n\\nAbstract: Location-based advertising is an entrepreneurial and innovative means for advertisers to reach out through personalised messages sent directly to mobile phones using their geographic location. The mobile phone users' willingness to disclose their location and other personal information is essential for the successful implementation of mobile location-based advertising (MLBA). Despite the potential enhancement of the user experience through such personalisation and the improved interaction with the marketer, there is an increasing tension between that personalisation and mobile users' concerns about privacy. While the privacy calculus theory (PCT) suggests that consumers make privacy-based decisions by evaluating the benefits any information may bring against the risk of its disclosure, this study examines the specific risks and benefits that influence consumers' acceptance of MLBA. A conceptual model is proposed based on the existing literature and a standardised survey was developed and targeted at individuals with known interests in the subject matter. From these requests, 252 valid responses were received and used to evaluate the key benefits and risks of MLBA from the users' perspectives. While the results confirmed the importance of internet privacy concerns (IPC) as an important determinant, they also indicate that monetary rewards and intrusiveness have a notably stronger impact on acceptance intentions towards MLBA. Intrusiveness is the most important risk factor in determining mobile users' intentions to accept MLBA and therefore establishing effective means of minimising the perceived intrusiveness of MLBA can be expected to have the greatest impact on achieving effective communications with mobile phone users.\",\n \"Title: Citizens' Perception About M-Government Services: Results From An Exploratory Survey\\nYear: 2019\\n\\nAbstract: The development of mobile technology is facilitating the transformation in a way that governments deliver their services. Mobile government is one area that has received very little research, but it can have a tremendous impact on the way citizens engage with their government. This research analyses the data gathered from 81 respondents through online survey on the various aspects of mobile government and collects their views on some of the key questions related to the use of mobile government. The findings showed that although citizens are aware of the possibilities they hardly used mobile devices as a direct communication channel with government. Most users tend to use social media platforms and social media is used as an intermediary between government and citizens. The findings of this research also indicated that although the users are well aware of m-government services and own smartphones, only a handful of them use their mobiles for accessing government services.\",\n \"Title: The battle of Brain vs. Heart: A literature review and meta-analysis of \\\"hedonic motivation\\\" use in UTAUT2.\\nYear: 2019\\n\\nAbstract: Much of the scholarly debate on the extrinsic-intrinsic motivation dichotomy to date has focused on organisational context. However, the recent upsurge of technology use amongst individuals in non-organisational context has led to consumer-focused research model such as extended unified theory of acceptance and use of technology (UTAUT2). The objective of this study is to bring back much needed focus on motivation dichotomy from the consumer perspective. This involved a systematic review and meta-analysis of hedonic motivation an affective construct in UTAUT2 studies. The findings from 79 UTAUT2 empirical studies revealed that only 46 studies (58%) utilised hedonic motivation while the remaining 33 studies (42%) omitted the construct. Extrinsic motivation was the major driver of non-hedonic and non-significant hedonic motivation studies with individuals using technologies for utilitarian outcomes. Unlike UTAUT2, moderators association of hedonic motivation were non-significant in determining consumer intention to use technology. The findings also revealed an important association between hedonic motivation and effort expectancy, in addition to fruitful directions for research and practice.\",\n \"Title: Elucidation of IS project success factors: an interpretive structural modelling approach\\nYear: 2020\\n\\nAbstract: This study extends the debate surrounding the components of IS project success by reviewing success factors from the perspective of their interdependency and influence on each other. This research utilises interpretive structural modelling as the methodology and framework to develop the relationships between the selected factors. This approach is presented as a mechanism that can provide greater insight to the underlying causal interrelationships associated with IS project success and the successful transition to operations. The findings identify a number of key outcomes that have significant driving influence on other interconnected factors in the final model. This study highlights the benefits of an interpretive approach where IS factor interrelationships can be modelled to demonstrate potential influence on other connected factors thereby, increasing the chances of project success.\",\n \"Title: Disaster management in Bangladesh: developing an effective emergency supply chain network\\nYear: 2019\\n\\nAbstract: This study has addressed and identified the problems in managing the existing emergency supply chain of Bangladesh in all phases of operation in terms of the primary drivers of the supply chain. It has also attempted to conceptualize and suggest an effective emergency supply chain. In this context, a thorough field investigation in several districts was conducted among the employees of the organizations sharing common information with similar protocols and implications (interoperable). Information was collected from the employees of all the participating organizations involved in disaster management through a semi-structured questionnaire based survey. The respondents addressed and illustrated several interconnected reasons which are inhibiting proper forecasting, procurement, storage, identification of affected people, and distribution. The respondents pointed out that the mismatching of objectives in the different organizations resulted in non-interoperability among the participating organizations. These issues are related to the malfunctioning of management with multidimensional organizational conflicts. Reflecting those issues, an emergency supply chain for disaster management is proposed in this study.\",\n \"Title: Smart Monitoring and Controlling of Government Policies Using Social Media and Cloud Computing\\nYear: 2020\\n\\nAbstract: The governments, nowadays, throughout the world are increasingly becoming dependent on public opinion regarding the framing and implementation of certain policies for the welfare of the general public. The role of social media is vital to this emerging trend. Traditionally, lack of public participation in various policy making decision used to be a major cause of concern particularly when formulating and evaluating such policies. However, the exponential rise in usage of social media platforms by general public has given the government a wider insight to overcome this long pending dilemma. Cloud-based e-governance is currently being realized due to IT infrastructure availability along with mindset changes of government advisors towards realizing the various policies in a best possible manner. This paper presents a pragmatic approach that combines the capabilities of both cloud computing and social media analytics towards efficient monitoring and controlling of governmental policies through public involvement. The proposed system has provided us some encouraging results, when tested for Goods and Services Tax (GST) implementation by Indian government and established that it can be successfully implemented for efficient policy making and implementation.\",\n \"Title: Impact of acculturation, online participation and involvement on voting intentions\\nYear: 2019\\n\\nAbstract: This study examines the extent to which acculturation and enculturation orientations affect online political participation, political involvement and voting intentions among a sample of Turkish-Dutch immigrants. The study uses data from Turkish-Dutch participants. Structural Equations Modelling (SEM) is employed for assessing the relationships in the conceptualized model. The findings show that enculturation and acculturation influence online participation and involvement, which in turn, are related to voting intentions. The study further examines the mediating role of political involvement and online political participation. Political involvement mediates the relationships between enculturation and acculturation and voting intentions. The results further indicate the effect of online participation on voting intentions is mediated by political involvement. The study findings provide insights into offline and online cultural and civic engagement tendencies among an important immigrant segment that policy makers should consider in the future.\",\n \"Title: The Effect Of Electronic Word Of Mouth Communications On Intention To Buy: A Meta-Analysis\\nYear: 2020\\n\\nAbstract: The aim of this research is to synthesise findings from previous studies by employing weight and meta-analysis to reconcile conflicting evidence and draw a \\\"big picture\\\" of eWOM factors influencing consumers' intention to buy. By using the findings from 69 studies, this research identified best (e.g. argument quality, valence, eWOM usefulness, trust in message), promising (e.g. eWOM credibility, emotional trust, attitude towards website) and least effective (e.g. volume, existing eWOM, source credibility) predictors of intention to buy in eWOM research. Additionally, the effect size of each predictor was calculated by performing meta-analysis. For academics, understanding what influences consumers' intention to buy will help set the agenda for future research directions; for practitioners, it will provide benefit in terms of practical guidance based on detailed analysis of specific factors influencing consumers' intention to buy, which could enhance their marketing activities.\",\n \"Title: Impact of COVID-19 pandemic on information management research and practice: Transforming education, work and life\\nYear: 2020\\n\\nAbstract: •This paper presents an assessment of the key challenges of COVID-19 through an IS and IM lens.•The pandemic has forced governments and decision makers to reassess the use of IS and technology.•AI could engender better, more informed decision making during crisis management scenarios.•Privacy and security are key underlying concerns for many citizens during the pandemic.•In developing countries, the digital divide is most apparent due to social and cultural barriers.\",\n \"Title: Social media analytics for end-users' expectation management in information systems development projects\\nYear: 2021\\n\\nAbstract: Purpose This study, an exploratory research, aims to investigate social media users' expectations of information systems (IS) products that are conceived but not yet launched. It specifically analyses social media data from Twitter about forthcoming smartphones and smartwatches from Apple and Samsung, two firms known for their innovative gadgets. Design/methodology/approach Tweets related to the following four forthcoming IS products were retrieved from 1st January 2020 to 30th September 2020: (1) Apple iPhone 12 (6,125 tweets), (2) Apple Watch 6 (553 tweets), (3) Samsung Galaxy Z Flip 2 (923 tweets) and (4) Samsung Galaxy Watch Active 3 (207 tweets). These 7,808 tweets were analysed using a combination of the Natural Language Processing Toolkit (NLTK) and sentiment analysis (SentiWordNet). Findings The online community was quite vocal about topics such as design, camera and hardware specifications. For all the forthcoming gadgets, the proportion of positive tweets exceeded that of negative tweets. The most prevalent sentiment expressed in Apple-related tweets was neutral, but in Samsung-related tweets was positive. Additionally, it was found that the proportion of tweets echoing negative sentiment was lower for Apple compared with Samsung. Originality/value This paper is the earliest empirical work to examine the degree to which social media chatter can be used by project managers for IS development projects, specifically for the purpose of end-users' expectation management.\",\n \"Title: Usage of augmented reality (AR) and development of e-learning outcomes: An empirical evaluation of students' e-learning experience\\nYear: 2022\\n\\nAbstract: This study aims to examine students' experience of augmented reality learning applications (AR. LRP). Uses and gratifications theory was proposed as a theoretical foundation of the current study's conceptual model. Four dimensions of UGT benefits were proposed as key antecedences of the students' experience with AR.LRP: personal interactive benefits, social interactive benefits, affective benefits, and cognitive benefits. The model was also extended by considering the role of telepresence. Further, technostress was proposed on the current study to moderate the relationship between the aspects of UGT and e-learning experience. A sample size of 500 undergraduate students from the four largest Universities in Saudi Arabia was used in the current study survey. The statistical results largely support the significant impact of personal interactive benefits, affective benefits, and cognitive benefits, and telepresence on student experience with AR.LRP. Technostress was also found to significantly moderate the relationship between UGT dimensions and student experience with AR.LRP. Further, results support a significant relationship between student experience with AR.LRP and students' learning performance. This study has contributed to the perspectives of researchers and practitioners by highlighting the most important aspects and characteristics that ensure a distinctive and positive students' experience of the drum with applications with AR.LRP.\",\n \"Title: Analysis of challenges for blockchain adoption within the Indian public sector: an interpretive structural modelling approach\\nYear: 2022\\n\\nAbstract: Purpose Blockchain is one of the most significant emerging technologies that is set to transform many aspects of industry and society. However, it has several major technical, social, legal, environmental and ethical complexities that offer significant challenges for mainstream use within the public sector. The coronavirus disease 2019 (COVID-19) pandemic has compelled many public sector employees to work remotely, highlighting a number of challenges to blockchain adoption within the Indian context signifying the pertinence of this research topic in the post-pandemic era. This study offers insight to researchers and policymakers alike on how such challenges are interdependent within this important subject. Design/methodology/approach We explored 16 unique sets of challenges selected from the literature and gathered data from nine experts from government settings, healthcare and education sectors and academia who have significant knowledge and experience of blockchain implementation and use in their respective organisations. The implementation of Interpretive Structural Modelling (ISM) and Matriced' Impacts Croise's Multiplication Appliquee a UN Classement (MICMAC) provided a precise set of driving, linkage and dependent challenges that were used to formulate the framework. Findings The developed ISM framework is split into six different levels. The results suggest that the bottom level consists of challenges such as \\\"Lack of standards (C9)\\\" and \\\"Lack of validation (C10)\\\" form the foundation of the hierarchical structure of blockchain adoption. However, the topmost level consists of a highly dependent challenge termed \\\"adoption of blockchain in the public sector (C16)\\\". The research filters the selected set of five challenges to develop a parsimonious model and formulated six propositions to examine the impact of \\\"lack of standard (C9)\\\", \\\"lack of validation (C10)\\\" on \\\"security issues (C3)\\\" and \\\"privacy concerns (C2)\\\", which eventually determine individuals' \\\"reluctance to use blockchain technology (C12)\\\". Originality/value This research fills a key gap in exiting research by exploring the key challenges in blockchain adoption within the public sector by developing a valuable framework to model this important topic. To the best of our knowledge, this is the first paper to address these challenges and develop a parsimonious model for challenges of blockchain adoption in the public sector settings.\",\n \"Title: Indian Travellers’ Adoption of Airbnb Platform\\nYear: 2022\\n\\nAbstract: Much of the existing scholarly debate on sharing economy to date has focused on the use of technology in developed countries. However, the recent upsurge of mobile technology adoption in developing countries has provided suitable breeding ground for sharing economy. The lack of native theories in tourism and hospitality sector with scare utilization of unified theory of acceptance and use of technology (UTAUT) provide necessity for this research. This study adapted meta-UTAUT model as theoretical lens and extended the model with hedonic motivation, trust, and self-efficacy. Based on data from 301 potential Indian consumers, the results underscored the central role of attitude that significantly mediated the effects of effort expectancy, social influence, and facilitating conditions on consumer intention to use Airbnb. Meanwhile, performance expectancy emerged as significant direct determinant of intention alongside attitude, trust, and self-efficacy. The proposed model explained as much as 65% variance on Indian consumer’s intention to use Airbnb.\",\n \"Title: Climate change and COP26: Are digital technologies and information management part of the problem or the solution? An editorial reflection and call to action\\nYear: 2022\\n\\nAbstract: The UN COP26 2021 conference on climate change offers the chance for world leaders to take action and make urgent and meaningful commitments to reducing emissions and limit global temperatures to 1.5 °C above pre-industrial levels by 2050. Whilst the political aspects and subsequent ramifications of these fundamental and critical decisions cannot be underestimated, there exists a technical perspective where digital and IS technology has a role to play in the monitoring of potential solutions, but also an integral element of climate change solutions. We explore these aspects in this editorial article, offering a comprehensive opinion based insight to a multitude of diverse viewpoints that look at the many challenges through a technology lens. It is widely recognized that technology in all its forms, is an important and integral element of the solution, but industry and wider society also view technology as being part of the problem. Increasingly, researchers are referencing the importance of responsible digitalization to eliminate the significant levels of e-waste. The reality is that technology is an integral component of the global efforts to get to net zero, however, its adoption requires pragmatic tradeoffs as we transition from current behaviors to a more climate friendly society.\",\n \"Title: Attention-Based LSTM Network for Rumor Veracity Estimation of Tweets\\nYear: 2022\\n\\nAbstract: Twitter has become a fertile place for rumors, as information can spread to a large number of people immediately. Rumors can mislead public opinion, weaken social order, decrease the legitimacy of government, and lead to a significant threat to social stability. Therefore, timely detection and debunking rumor are urgently needed. In this work, we proposed an Attention-based Long-Short Term Memory (LSTM) network that uses tweet text with thirteen different linguistic and user features to distinguish rumor and non-rumor tweets. The performance of the proposed Attention-based LSTM model is compared with several conventional machine and deep learning models. The proposed Attention-based LSTM model achieved an F1-score of 0.88 in classifying rumor and non-rumor tweets, which is better than the state-of-the-art results. The proposed system can reduce the impact of rumors on society and weaken the loss of life, money, and build the firm trust of users with social media platforms.\",\n \"Title: Assessing Consumers’ Co‐production and Future Participation On Value Co‐creation and Business Benefit: an F-P-C-B Model Perspective\\nYear: 2022\\n\\nAbstract: Co-production and active participation of the consumers are considered to have enhanced the value co-creation activities that would ensure business benefits of a firm. The marketing literature available does not explicitly explain the philosophy that would motivate the consumers to help to increase values for co-creation activities. In this context, attempts have been made to identify the factors that would impact on co-production and consumers’ participation to co-create values. By studying literature and theories such as theory of co-creation, theory of value creation, information processing theory, marketing theory and expectancy value theory, a conceptual model called F-P-C-B (Future Participation (F) - Co-production (P) - Co-creation (C) - Business Benefit (B)) has been developed along with nine hypotheses. The data was from 362 respondents in India and the model was tested using PLS based analysis. The study shows that it is important for the firms to shift from product-oriented activities to customer-related strategies. It is also found that for obtaining more profitability and better business results, customers should be involved in business activities by way of involving in co-design, idea generation, and other relevant activities of the firms. Moreover, the study highlights that knowledge sharing between the customers and the firm authorities ensures better business values.\",\n \"Title: Understanding the drivers of online trust and intention to buy on a website: An emerging market perspective\\nYear: 2022\\n\\nAbstract: In recent years, examining the determinants and outcomes of online trust in emerging online markets in the North Africa Region has been lacking. Therefore, the purpose of this study is twofold: first, to gain knowledge of the key predictors of online trust in Morocco; second, to investigate the consequences of online trust on perceived risk, attitude, and online purchase intentions in Morocco. A research model based on the work of Jarvenpaa et al. (2000) was empirically tested. Data was collected from a total of 414 experienced online buyers through online surveys. The PLS approach using SmartPLS 3 was performed to test the hypotheses. The results demonstrate that the effect of perceived size and perceived reputation on online trust is positively significant; online trust has a significant positive influence on attitude and significant negative influence on perceived risk; online trust and attitude positively influence purchase intention; perceived risk has a significant negative effect on attitude and the negative influence of perceived risk on purchase intentions was found to be not significant. The post-hoc analysis further shows that attitude transmits completely the effect of perceived risk on purchase intention, while perceived risk partially mediates the effects of online trust on attitude.\",\n \"Title: Artificial Intelligence for data-driven decision-making and governance in public affairs\\nYear: 2022\\n\\nAbstract: Literature shows there is a growing interest in studies involving Artificial Intelligence (AI) in the public sector; and while there is evidence of many governmental initiatives that have been established to harness the power of AI, empirical research on the topic and evidence-based insights are rather lacking. The aim of this Special Issue on Artificial Intelligence for Data-Driven Decision-Making and Governance in Public Affairs is to extend both the theoretical and practical boundaries of AI research in the public sector in order to improve governmental decision-making and governance, thus enhancing public value creation. The papers in this special issue focus on AI risks and guidelines, AI governance, the risks of governmental implementation of AI to citizens' privacy, increasing citizen satisfaction through AI-enabled government services, the enablers and challenges of AI implementation in specific public sectors, and using AI to study political opinion. These papers not only advance our knowledge and understanding of the use of AI in government and public governance, but they also help to set out a renewed research agenda. Future research should, among other things, focus on inter- and multi-disciplinary empirical studies that call for the collaboration of a variety of stakeholders; on the longitudinal dynamics of creating public value through the breadth and depth of AI assimilation; and on the investigation of the ethical challenges (particularly data privacy) in AI implementation.\",\n \"Title: Predicting ratings of social media feeds: combining latent-factors and emotional aspects for improving performance of different classifiers\\nYear: 2022\\n\\nAbstract: Purpose The widespread acceptance of various social platforms has increased the number of users posting about various services based on their experiences about the services. Finding out the intended ratings of social media (SM) posts is important for both organizations and prospective users since these posts can help in capturing the user's perspectives. However, unlike merchant websites, the SM posts related to the service-experience cannot be rated unless explicitly mentioned in the comments. Additionally, predicting ratings can also help to build a database using recent comments for testing recommender algorithms in various scenarios. Design/methodology/approach In this study, the authors have predicted the ratings of SM posts using linear (Naive Bayes, max-entropy) and non-linear (k-nearest neighbor, k-NN) classifiers utilizing combinations of different features, sentiment scores and emotion scores. Findings Overall, the results of this study reveal that the non-linear classifier (k-NN classifier) performed better than the linear classifiers (Naive Bayes, Max-entropy classifier). Results also show an improvement of performance where the classifier was combined with sentiment and emotion scores. Introduction of the feature \\\"factors of importance\\\" or \\\"the latent factors\\\" also show an improvement of the classifier performance. Originality/value This study provides a new avenue of predicting ratings of SM feeds by the use of machine learning algorithms along with a combination of different features like emotional aspects and latent factors.\"\n]","isConversational":false},"profile_size":{"kind":"number","value":67,"string":"67"},"task":{"kind":"string","value":"longlamp_2"},"split_kind":{"kind":"string","value":"user_based"},"id":{"kind":"number","value":84,"string":"84"}}},{"rowIdx":85,"cells":{"question_id":{"kind":"string","value":"Fernando Pereira"},"question":{"kind":"string","value":"Generate an abstract for the title \"Epipolar based light field key-location detector\" using the following items: visual features, light field cameras, feature detection, lenslet light field format, Epipolar Planar Image (EPI)"},"answer":{"kind":"string","value":"Nowadays, visual features play a key role, as they can provide a concise representation of visual data that is efficient for multiple tasks, notably content retrieval and object recognition. In parallel, visual sensors have been improving, targeting richer acquisitions of the light in a visual scene. In this context, the so-called light field cameras, which have recently emerged, are able to go beyond the standard acquisition models, by enriching the visual representation with directional light measures for each pixel position, e.g. by using a so-called lenslet light field camera. At this stage, not much research has been made in the field of feature detection and description for the emerging lenslet light field format. In this context, this paper proposes a feature detector suitable for lenslet light field images based on the exploitation of an alternative visual parametrization of the light field, called the Epipolar Planar Image (EPI). The proposed detector is heavily based on line detection in the EPI representation, since 3D points in the visual scene are mapped to line segments in an EPI, and the detector output is referred as key-locations. The proposed light field key-location detector is assessed with a solid evaluation framework using a large light field dataset. In comparison to the 2D SIFT detector, up to 10% improvements were achieved for the widely used repeatability metric."},"correct_answer":{"kind":"string","value":"Nowadays, visual features play a key role, as they can provide a concise representation of visual data that is efficient for multiple tasks, notably content retrieval and object recognition. In parallel, visual sensors have been improving, targeting richer acquisitions of the light in a visual scene. In this context, the so-called light field cameras, which have recently emerged, are able to go beyond the standard acquisition models, by enriching the visual representation with directional light measures for each pixel position, e.g. by using a so-called lenslet light field camera. At this stage, not much research has been made in the field of feature detection and description for the emerging lenslet light field format. In this context, this paper proposes a feature detector suitable for lenslet light field images based on the exploitation of an alternative visual parametrization of the light field, called the Epipolar Planar Image (EPI). The proposed detector is heavily based on line detection in the EPI representation, since 3D points in the visual scene are mapped to line segments in an EPI, and the detector output is referred as key-locations. The proposed light field key-location detector is assessed with a solid evaluation framework using a large light field dataset. In comparison to the 2D SIFT detector, up to 10% improvements were achieved for the widely used repeatability metric."},"documents":{"kind":"list like","value":["Title: The MPEG-21 Standard: Why an Open Multimedia Framework?\nYear: 2001\n\nAbstract: MPEG [1] has been responsible for the successful MPEG-1 and MPEG-2 standards that have given rise to widely adopted commercial products and services, such as Video-CD, DVD, digital television, digital audio broadcasting (DAB) and MP3 (MPEG-1 Audio layer 3) players and recorders. More recently, the MPEG-4 standard [2] is aimed to define an audiovisual coding standard to address the emerging needs of the communication, interactive and broadcasting service models as well as of the mixed service models resulting from their technological convergence. The MPEG-4 object-based representation approach where a scene is modeled as a composition of objects, both natural and synthetic, with which the user may interact, is at the heart of the MPEG-4 technology. With this new coding approach, the MPEG-4 standard opens new frontiers in the way users will play with, create, re-use, access and consume audiovisual content. Following the same vision underpinning MPEG-4, MPEG initiated after another standardization project addressing the problem of describing multimedia content to allow the quick and efficient searching, processing and filtering of various types of multimedia material: MPEG-7 [3]. The need for a powerful solution for quickly and efficiently identifying, searching, filtering, etc., various types of multimedia content of interest to the user, human or machine, using also non text-based technologies, directly follows from the urge to efficiently use the available multimedia content and the difficulty of doing so.","Title: Proposal for an Integrated Video Analysis Framework\nYear: 1998\n\nAbstract: The analysis of video data targeting the identification of relevant objects and the extraction of associated descriptive characteristics will be the enabling factor for a number of multimedia applications. This process has intrinsic difficulties, and since semantic criteria are difficult to express, usually only a part of the desired analysis results can be automatically achieved. For many applications, the automatic tools can be complemented with user guidance to improve performance.This paper proposes an integrated framework for video analysis, addressing the video segmentation and feature extraction problems. The framework includes a set of modules that can be combined following specific application needs. It includes both automatic (more objective) and user interaction (more semantic) analysis modules. The paper also proposes a specific segmentation solution to one of the most relevant application scenarios considered - off-line applications requiring precise segmentation.","Title: Motion compensated refinement for low complexity pixel based distributed video coding\nYear: 2005\n\nAbstract: Distributed video coding (DVC) is a new coding paradigm that enables to exploit video statistics, partially or totally at the decoder. A particular case of DVC, Wyner-Ziv coding, deals with lossy source coding with side information at the decoder and allows a shift of complexity from the encoder to the decoder, theoretically without any penalty in the coding efficiency. The Wyner- Ziv solution here described encodes each video frame independently (intraframe coding), but decodes the same frame conditionally (interframe decoding). At the decoder, motion estimation and compensation tools are responsible to obtain an accurate interpolation of the original frame using previously decoded (temporally adjacent) frames. This paper proposes a novel approach to improve the performance of pixel domain Wyner-Ziv video coding by using a motion compensated refinement of the decoded frame and use it as improved side information. More precisely, upon partial decoding of each frame, the decoder refines its motion trajectories in order to achieve a better reconstruction of the decoded frame.","Title: Posterior Sparsity in Unsupervised Dependency Parsing\nYear: 2011\n\nAbstract: A strong inductive bias is essential in unsupervised grammar induction. In this paper, we explore a particular sparsity bias in dependency grammars that encourages a small number of unique dependency types. We use part-of-speech (POS) tags to group dependencies by parent-child types and investigate sparsity-inducing penalties on the posterior distributions of parent-child POS tag pairs in the posterior regularization (PR) framework of Graça et al. (2007). In experiments with 12 different languages, we achieve significant gains in directed attachment accuracy over the standard expectation maximization (EM) baseline, with an average accuracy improvement of 6.5%, outperforming EM by at least 1% for 9 out of 12 languages. Furthermore, the new method outperforms models based on standard Bayesian sparsity-inducing parameter priors with an average improvement of 5% and positive gains of at least 1% for 9 out of 12 languages. On English text in particular, we show that our approach improves performance over other state-of-the-art techniques.","Title: Automatically annotating documents with normalized gene lists.\nYear: 2005\n\nAbstract: Document gene normalization is the problem of creating a list of unique identifiers for genes that are mentioned within a document. Automating this process has many potential applications in both information extraction and database curation systems. Here we present two separate solutions to this problem. The first is primarily based on standard pattern matching and information extraction techniques. The second and more novel solution uses a statistical classifier to recognize valid gene matches from a list of known gene synonyms.We compare the results of the two systems, analyze their merits and argue that the classification based system is preferable for many reasons including performance, simplicity and robustness. Our best systems attain a balanced precision and recall in the range of 74%-92%, depending on the organism.","Title: Optimized MVC Prediction Structures for Interactive Multiview Video Streaming.\nYear: 2013\n\nAbstract: The Multiview Video Coding (MVC) standard efficiently compresses multiview video by considering spatial, temporal and interview correlations. This letter studies the impact of the MVC interview prediction structure on both the transmission and the overall coding rates for an interactive multiview video streaming system, considering both unicast and multicast scenarios, with the user interactive behavior represented by some view-popularity model. We propose a method to identify the optimal prediction structure minimizing the visual distortion, given some storage and link capacities constraints. Simulation results confirm that the optimal prediction structure results from a non-trivial tradeoff between the system constraints, the transmission model and the views' popularity.","Title: Large-scale cross-document coreference using distributed inference and hierarchical models\nYear: 2011\n\nAbstract: Cross-document coreference, the task of grouping all the mentions of each entity in a document collection, arises in information extraction and automated knowledge base construction. For large collections, it is clearly impractical to consider all possible groupings of mentions into distinct entities. To solve the problem we propose two ideas: (a) a distributed inference technique that uses parallelism to enable large scale processing, and (b) a hierarchical model of coreference that represents uncertainty over multiple granularities of entities to facilitate more effective approximate inference. To evaluate these ideas, we constructed a labeled corpus of 1.5 million disambiguated mentions in Web pages by selecting link anchors referring to Wikipedia entities. We show that the combination of the hierarchical model with distributed inference quickly obtains high accuracy (with error reduction of 38%) on this large dataset, demonstrating the scalability of our approach.","Title: A State-Space Based Model-Checking Framework for Embedded System Controllers Specified Using IOPT Petri Nets.\nYear: 2012\n\nAbstract: This paper presents a state-space based model-checking framework to test and validate embedded system controllers specified using the [OPT Petri net formalism. The framework is composed of an automatic software code generator, a state-space generator and a query engine, used to define queries applied to the resulting state-space graphs. During state-space generation, the tools collect information required to enable the efficient implementation of hardware/software controllers, including place bounds, deadlocks and conflicts between concurrent transitions. User defined queries can check relevant system properties, as the occurrence of undesired error situations, the reachability of desired states, system liveliness and the occurrence of deadlocks and livelocks. The new tool, available online under a Web based user interface, provides a fast and efficient way to test and validate system controllers, contributing to the reduction of development time.","Title: Side information creation for efficient Wyner-Ziv video coding: Classifying and reviewing\nYear: 2013\n\nAbstract: Video coding technologies have played a major role in the explosion of large market digital video applications and services. In this context, the very popular MPEG-x and H-26x video coding standards adopted a predictive coding paradigm, where complex encoders exploit the data redundancy and irrelevancy to 'control' much simpler decoders. This codec paradigm fits well applications and services such as digital television and video storage where the decoder complexity is critical, but does not match well the requirements of emerging applications such as visual sensor networks where the encoder complexity is more critical. The Slepian-Wolf and Wyner-Ziv theorems brought the possibility to develop the so-called Wyner-Ziv video codecs, following a different coding paradigm where it is the task of the decoder, and not anymore of the encoder, to (fully or partly) exploit the video redundancy. Theoretically, Wyner-Ziv video coding does not incur in any compression performance penalty regarding the more traditional predictive coding paradigm (at least for certain conditions). In the context of Wyner-Ziv video codecs, the so-called side information, which is a decoder estimate of the original frame to code, plays a critical role in the overall compression performance. For this reason, much research effort has been invested in the past decade to develop increasingly more efficient side information creation methods. This paper has the main objective to review and evaluate the available side information methods after proposing a classification taxonomy to guide this review, allowing to achieve more solid conclusions and better identify the next relevant research challenges. After classifying the side information creation methods into four classes, notably guess, try, hint and learn, the review of the most important techniques in each class and the evaluation of some of them leads to the important conclusion that the side information creation methods provide better rate-distortion (RD) performance depending on the amount of temporal correlation in each video sequence. It became also clear that the best available Wyner-Ziv video coding solutions are almost systematically based on the learn approach. The best solutions are already able to systematically outperform the H.264/AVC Intra, and also the H.264/AVC zero-motion standard solutions for specific types of content.","Title: Distributed video coding: Selecting the most promising application scenarios\nYear: 2008\n\nAbstract: Distributed Video Coding (DVC) is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Recently, practical DVC solutions have been proposed with promising results; however, there is still a need to study in a more systematic way the set of application scenarios for which DVC may bring major advantages. This paper intends to contribute for the identification of the most DVC friendly application scenarios, highlighting the expected benefits and drawbacks for each studied scenario. This selection is based on a proposed methodology which involves the characterization and clustering of the applications according to their most relevant characteristics, and their matching with the main potential DVC benefits.","Title: Binary tree decomposition depth coding for 3D video applications\nYear: 2011\n\nAbstract: Recent advances in three dimensional display technologies and the growing efforts put in the production of three dimensional videos are intensely demanding for new, more efficient three dimensional content representation formats. One promising for mat is the so-called multiview plus depth format where multiple views of the observed scene are represented together with a per pixel depth map. Naturally, this format requires to efficiently code not only the video views but also the depth data. In this context, this paper proposes a novel depth map codec encoding the depth data by means of a binary tree triangular decomposition and reconstructing the depth map values by means of a tri angle based planar approximation. For depth maps related to typical three dimensional video contents, the proposed depth map codec outperforms both the H.264/AVC standard with all intra coding modes enabled and the JPEG standard. In particular, for the same objective reconstruction quality, the proposed codec allows an average bitrate reduction of 60% and 90% regarding H.264/AVC Intra and JPEG coding, respectively.","Title: Stand-alone objective segmentation quality evaluation\nYear: 2002\n\nAbstract: The identification of objects in video sequences, that is, video segmentation, plays a major role in emerging interactive multimedia services, such as those enabled by the ISO MPEG-4 and MPEG-7 standards. In this context, assessing the adequacy of the identified objects to the application targets, that is, evaluating the segmentation quality, assumes a crucial importance. Video segmentation technology has received considerable attention in the literature, with algorithms being proposed to address various types of applications. However, the segmentation quality performance evaluation of those algorithms is often ad hoc, and a well-established solution is not available. In fact, the field of objective segmentation quality evaluation is still maturing; recently, some more efforts have been made, mainly following the emergence of the MPEG object-based coding and description standards. This paper discusses the problem of objective segmentation quality evaluation in its most difficult scenario: stand-alone evaluation, that is when a reference segmentation is not available for comparative evaluation. In particular, objective metrics are proposed for the evaluation of stand-alone segmentation quality for both individual objects and overall segmentation partitions.","Title: Advanced side information creation techniques and framework for Wyner-Ziv video coding\nYear: 2008\n\nAbstract: Recently, several distributed video coding (DVC) solutions based on the distributed source coding (DSC) paradigm have appeared in the literature. Wyner-Ziv (WZ) video coding, a particular case of DVC where side information is made available at the decoder, enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill novel requirements from applications such as video surveillance, sensor networks and mobile camera phones. The quality of the side information at the decoder has a critical role in determining the WZ video coding rate-distortion (RD) performance, notably to raise it to a level as close as possible to the RD performance of standard predictive video coding schemes. Towards this target, efficient motion search algorithms for powerful frame interpolation are much needed at the decoder. In this paper, the RD performance of a Wyner-Ziv video codec is improved by using novel, advanced motion compensated frame interpolation techniques to generate the side information. The development of these type of side information estimators is a difficult problem in WZ video coding, especially because the decoder only has available some reference, decoded frames. Based on the regularization of the motion field, novel side information creation techniques are proposed in this paper along with a new frame interpolation framework able to generate higher quality side information at the decoder. To illustrate the RD performance improvements, this novel side information creation framework has been integrated in a transform domain turbo coding based Wyner-Ziv video codec. Experimental results show that the novel side information creation solution leads to better RD performance than available state-of-the-art side information estimators, with improvements up to 2dB; moreover, it allows outperforming H.264/AVC Intra by up to 3dB with a lower encoding complexity.","Title: Exploiting Feature Covariance in High-Dimensional Online Learning\nYear: 2010\n\nAbstract: Some online algorithms for linear classifica- tion model the uncertainty in their weights over the course of learning. Modeling the full covariance structure of the weights can provide a significant advantage for classifica- tion. However, for high-dimensional, large- scale data, even though there may be many second-order feature interactions, it is com- putationally infeasible to maintain this co- variance structure. To extend second-order methods to high-dimensional data, we de- velop low-rank approximations of the covari- ance structure. We evaluate our approach on both synthetic and real-world data sets us- ing the confidence-weighted (Dredze et al., 2008; Crammer et al., 2009a) online learning framework. We show improvements over di- agonal covariance matrices for both low and high-dimensional data.","Title: Weakly-supervised acquisition of labeled class instances using graph random walks\nYear: 2008\n\nAbstract: We present a graph-based semi-supervised label propagation algorithm for acquiring open-domain labeled classes and their instances from a combination of unstructured and structured text sources. This acquisition method significantly improves coverage compared to a previous set of labeled classes and instances derived from free text, while achieving comparable precision.","Title: Visual interactive subgroup discovery with numerical properties of interest\nYear: 2006\n\nAbstract: We propose an approach to subgroup discovery using distribution rules (a kind of association rules with a probability distribution on the consequent) for numerical properties of interest. The objective interest of the subgroups is measured through statistical goodness of fit tests. Their subjective interest can be assessed by the data analyst through a visual interactive subgroup browsing procedure.","Title: Hierarchical motion estimation for side information creation in Wyner-Ziv video coding\nYear: 2008\n\nAbstract: Recently, several video coding solutions based on the distributed source coding paradigm have appeared in the literature. Among them, Wyner-Ziv video coding schemes enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill requirements of emerging applications such as visual sensor networks and wireless surveillance. To achieve a performance comparable to the predictive video coding solutions, it is necessary to increase the quality of the side information, this means the estimation of the original frame created at the decoder. In this paper, a hierarchical motion estimation (HME) technique using different scales and increasingly smaller block sizes is proposed to generate a more reliable estimation of the motion field. The HME technique is integrated in a well known motion compensated frame interpolation framework responsible for the creation of the side information in a Wyner-Ziv video decoder. The proposed technique enables to achieve improvements in the rate-distortion (RD) performance up to 7 dB when compared to H.263+ Intra and 3 dB when compared to H.264/AVC Intra.","Title: Dynamic quality control for transform domain Wyner-Ziv video coding\nYear: 2009\n\nAbstract: Wyner-Ziv is an emerging video coding paradigm based on the Slepian-Wolf and Wyner-Ziv theorems where video coding may be performed by exploiting the temporal correlation at the decoder and not anymore at the encoder as in conventional video coding. This approach should allow designing low-complexity encoders, targeting important emerging applications such as wireless surveillance and visual sensor networks, without any cost in terms of RD performance. However, the currently available WZ video codecs do not allow controlling the target quality in an efficient way which is a major limitation for some applications. In this context, the main objective of this paper is to propose an efficient quality control algorithm to maintain a uniform quality along time in low-encoding complexity WZ video coding by dynamically adapting the quantization parameters depending on the desired target quality without any a priori knowledge about the sequence characteristics. This objective will be reached in the context of the so-called Stanford WZ video codec architecture which is currently the most used in the literature.","Title: Multiple UAV teams for multiple tasks.\nYear: 2009\n\nAbstract: In a search and prosecute mission, multiple heterogeneous unmanned aerial vehicles UAVs that carry different resources need to perform the classify, prosecute and battle damage assessment (BDA) tasks on targets sequentially. Depending on the target resource requirement, it may be necessary to deploy a coalition of UAVs to perform the action. In this paper, we propose coalition formation algorithms that have low computational overhead to determine coalitions for the prosecute and the BDA tasks. We also develop a simultaneous strike mechanism based on Dubins curves for the UAVs to prosecute the target simultaneously. Monte-Carlo simulation results are presented to show how the algorithms work and the effect of increasing the number of BDA tasks on the mission performance.","Title: Drift Reduction For A H.264/Avc Fine Grain Scalability With Motion Compensation Architecture\nYear: 2004\n\nAbstract: The recent advances in non-scalable video encoding brought by the H.264/AVC standard offered significant improvements in tenus of rate-distortion performance. This paper proposes a H.264/AVC based fine grain scalable video encoder which also exploits the motion compensation tools of the H.264/AVC standard to explore the temporal redundancy in the enhancement layer. The enhancement layer is predicted from a high quality reference obtained from past information of the enhancement and base layers. One of the drawbacks of this architecture is the drift effect., which occurs when part of the enhancement layer used for prediction is not received by the decoder. The drift reduction approaches here proposed simultaneously allow improvements in the coding efficiency and a reduction of the drift effect. The experimental results show improvements LIP to 2 dB in coding efficiency in comparison to Intra coding (like used by the MPEG-4 FGS standard) using the MPEG-4 testing conditions.","Title: Integrating low-level and semantic visual cues for improved image-to-video experiences\nYear: 2006\n\nAbstract: Nowadays, the heterogeneity of networks, terminals, and users is growing. At the same time, the availability and usage of multimedia content is increasing, which has raised the relevance of content adaptation technologies able to fulfill the needs associated to all usage conditions. For example, mobile displays tend to be too small to allow one to see all the details of an image. This paper presents an innovative method to integrate low-level and semantic visual cues into a unique visual attention map that represents the most interesting contents of an image, allowing the creation of a video sequence that browses through the image displaying its regions of interest in detail. The architecture of the developed adaptation system, the processing solutions and also the principles and reasoning behind the algorithms that have been developed and implemented are presented in this paper. Special emphasis is given to the integration of low-level and semantic visual cues for the maximization of the image to video adapted experience.","Title: Refreshment need metrics for improved shape and texture object-based resilient video coding\nYear: 2003\n\nAbstract: Video encoders may use several techniques to improve error resilience. In particular, for video encoders that rely on predictive (inter) coding to remove temporal redundancy, intra coding refreshment is especially useful to stop error propagation when errors occur in the transmission or storage of the coded streams, which can cause the decoded quality to decay very rapidly. In the context of object-based video coding, the video encoder can apply intra coding refreshment to both the shape and the texture data. In this paper, shape refreshment need and texture refreshment need metrics are proposed which can be used by object-based video encoders, notably MPEG-4 video encoders, to determine when the shape and the texture of the various video objects in the scene should be refreshed in order to improve the decoded video quality, e.g., for a given bit rate.","Title: Temporal shape error concealment by global motion compensation with local refinement\nYear: 2006\n\nAbstract: This paper presents an original temporal shape error concealment technique based on a combination of global and local motion compensation. For this technique, which is especially useful for object-based video applications in error-prone environments (e.g., mobile networks), it is assumed that the shape of the corrupted object at hand is in the form of a binary alpha plane and some of the shape data is missing due to channel errors. To conceal the corrupted shape, the decoder first assumes that a global motion model can describe the shape changes in consecutive time instants. This way, based on locally estimated global motion parameters, the decoder attempts to conceal the corrupted alpha plane by global motion compensating the shape data from the previous time instant. Afterwards, since a global motion model cannot perfectly describe all alpha plane changes, a local motion refinement is applied to improve the concealment in areas of the object with significant local motion.","Title: Reply Expectation Prediction for Email Management\nYear: 2005\n\nAbstract: We reduce email overload by addressing the problem of waiting for a reply to one's email. We predict whether sent and received emails necessitate a reply, enabling the user to both better manage his inbox and to track mail sent to others. We discuss the features used to discriminate emails, show promising initial results with a logistic regression model, and outline future directions for this work.","Title: Cell loss resilience for B-ISDN video communications\nYear: 1992\n\nAbstract: The increasing interest in video services is giving a new push for a network able to satisfy broadband services demand: the Broadband Integrated Services Digital Network directed to the support of a wide range of services in the same universal network. This network uses the Asynchronous Transfer Mode (ATM) based on the concept of packet transmission which enables variable bit rate information flows. The application of the variable bit rate capability to video coding opened new horizons to video communications among which the constant quality video coding assumes particular interest. This paper deals with the cell loss phenomenon which is a kind of degradation of information typical of ATM environments, and presents some cell loss recovering techniques as well as simulation results for video communications.","Title: The ORCHESTRA Collaborative Data Sharing System\nYear: 2008\n\nAbstract: Sharing structured data today requires standardizing upon a single schema, then mapping and cleaning all of the data. This results in a single queriable mediated data instance. However, for settings in which structured data is being collaboratively authored by a large community, e.g., in the sciences, there is often a lack of consensus about how it should be represented, what is correct, and which sources are authoritative. Moreover, such data is seldom static: it is frequently updated, cleaned, and annotated. The ORCHESTRA collaborative data sharing system develops a new architecture and consistency model for such settings, based on the needs of data sharing in the life sciences. In this paper we describe the basic architecture and implementation of the ORCHESTRA system, and summarize some of the open challenges that arise in this setting.","Title: The design principles of a weighted finite-state transducer library\nYear: 2000\n\nAbstract: We describe the algorithmic and software design principles of an object-oriented library for weighted finite-state transducers. By taking advantage of the theory of rational power series, we were able to achieve high degrees of generality, modularity and irredundancy, while attaining competitive efficiency in demanding speech processing applications involving weighted automata of more than 10 7 states and transitions. Besides its mathematical foundation, the design also draws from important ideas in algorithm design and programming languages: dynamic programming and shortest-paths algorithms over general semirings, object-oriented programming, lazy evaluation and memoization.","Title: Low delay distributed video coding with refined side information\nYear: 2011\n\nAbstract: Distributed video coding (DVC) is a new video coding paradigm based upon two fundamental theoretical results: the Slepian-Wolf and Wyner-Ziv theorems. Among other benefits, this new coding paradigm may allow a flexible complexity allocation between the encoder and the decoder. Several DVC codecs have been developed over the years addressing the specific requirements of emerging applications such as wireless video surveillance and sensor networks. While state-of-the-art DVC codecs, such as the DISCOVER DVC codec, have shown promising RD performance, most DVC codecs in the literature do not consider low delay requirements which are relevant for some of the addressed applications. In this context, the main objective and novelty of this paper is to propose an efficient, low delay and fully practical DVC codec based on the Stanford DVC architecture adopting a side information iterative refinement approach. The obtained performance results show that the developed DVC solution fulfils the objectives regarding relevant benchmarks, notably due to the novel side information creation and correlation noise modeling tools integrated in a side information iterative refinement framework.","Title: Low complexity intra mode selection for efficient distributed video coding\nYear: 2009\n\nAbstract: Motion compensated frame interpolation (MCFI) is one of the most efficient solutions to generate side information (SI) in the context of distributed video coding. However, it creates SI with rather significant motion compensated errors for some frame regions while rather small for some other regions depending on the video content. In this paper, a low complexity Intra mode selection algorithm is proposed to select the most 'critical' blocks in the WZ frame and help the decoder with some reliable data for those blocks. For each block, the novel coding mode selection algorithm estimates the encoding rate for the Intra based and WZ coding modes and determines the best coding mode while maintaining a low encoder complexity. The proposed solution is evaluated in terms of rate-distortion performance with improvements up to 1.2 dB regarding a WZ coding mode only solution.","Title: Error resilience and concealment performance for MPEG-4 frame-based video coding\nYear: 1999\n\nAbstract: This paper addresses the general problem of error resilience and concealment in the context of content-based video coding schemes, such as the new MPEG-4 video coding standard. In the first part of the paper, the most important error resilience tools available in the literature are studied, organized and classified according to three main classes, notably: error resilient source coding, channel coding and decoding, and error concealment. In the second part, the performance of the MPEG-4 error resilient frame-based syntax, which addresses simple mobile communications, is studied with a meaningful set of test conditions and three different concealment schemes. (C) 1999 Elsevier Science B.V. All rights reserved.","Title: Finite-state approximations of grammars\nYear: 1990\n\nAbstract: Grammars for spoken language systems are subject to the conflicting requirements of language modeling for recognition and of language analysis for sentence interpretation. Current recognition algorithms can most directly use finite-state acceptor (FSA) language models. However, these models are inadequate for language interpretation, since they cannot express the relevant syntactic and semantic regularities. Augmented phrase structure grammar (APSG) formalisms, such as unification grammars, can express many of those regularities, but they are computationally less suitable for language modeling, because of the inherent cost of computing state transitions in APSG parsers.","Title: Controlling complexity in part-of-speech induction\nYear: 2011\n\nAbstract: We consider the problem of fully unsupervised learning of grammatical (part-of-speech) categories from unlabeled text. The standard maximum-likelihood hidden Markov model for this task performs poorly, because of its weak inductive bias and large model capacity. We address this problem by refining the model and modifying the learning objective to control its capacity via parametric and non-parametric constraints. Our approach enforces word-category association sparsity, adds morphological and orthographic features, and eliminates hard-to-estimate parameters for rare words. We develop an efficient learning algorithm that is not much more computationally intensive than standard training. We also provide an open-source implementation of the algorithm. Our experiments on five diverse languages (Bulgarian, Danish, English, Portuguese, Spanish) achieve significant improvements compared with previous methods for the same task.","Title: Evaluating a feedback channel based transform domain Wyner-Ziv video codec\nYear: 2008\n\nAbstract: Wyner-Ziv (WZ) video coding-a particular case of distributed video coding (DVC)-is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. In recent years, some practical WZ video coding solutions have been proposed with promising results. One of the most popular WZ video coding architectures in the literature uses turbo codes based Slepian-Wolf coding and a feedback channel to perform rate control at the decoder. This WZ video coding architecture has been first proposed by researchers at Stanford University and has been after adopted and improved by many research groups around the world. However, while there are many papers published with changes and improvements to this architecture, the precise and detailed evaluation of its performance, targeting its deep understanding for future advances, has not been made. Available performance results are mostly partial, under unclear and incompatible conditions, using vaguely defined and also sometimes architecturally unrealistic codec solutions. This paper targets the provision of a detailed, clear, and complete performance evaluation of an advanced transform domain WZ video codec derived from the Stanford turbo coding and feedback channel based architecture. Although the WZ video codec proposed for this evaluation is among the best available, the main purpose and novelty of this paper is the solid and comprehensive performance evaluation made which will provide a strong, and very much needed, performance reference for researchers in this WZ video coding field, as well as a solid way to steer future WZ video coding research.","Title: A Deductive Account of Quantification in LFG.\nYear: 1994\n\nAbstract: The relationship between Lexical-Functional Grammar (LFG) functional\nstructures (f-structures) for sentences and their semantic interpretations can\nbe expressed directly in a fragment of linear logic in a way that explains\ncorrectly the constrained interactions between quantifier scope ambiguity and\nbound anaphora. The use of a deductive framework to account for the\ncompositional properties of quantifying expressions in natural language\nobviates the need for additional mechanisms, such as Cooper storage, to\nrepresent the different scopes that a quantifier might take. Instead, the\nsemantic contribution of a quantifier is recorded as an ordinary logical\nformula, one whose use in a proof will establish the scope of the quantifier.\nThe properties of linear logic ensure that each quantifier is scoped exactly\nonce. Our analysis of quantifier scope can be seen as a recasting of Pereira's\nanalysis (Pereira, 1991), which was expressed in higher-order intuitionistic\nlogic. But our use of LFG and linear logic provides a much more direct and\ncomputationally more flexible interpretation mechanism for at least the same\nrange of phenomena. We have developed a preliminary Prolog implementation of\nthe linear deductions described in this work.","Title: A tool for interactive subgroup discovery using distribution rules\nYear: 2007\n\nAbstract: We describe an approach and a tool for the discovery of subgroups within the framework of distribution rule mining. Distribution rules are a kind of association rules particularly suited for the exploratory study of numerical variables of interest. Being an exploratory technique, the result of a distribution mining process is typically a very large number of patterns. Exploring such results is thus a complex task and limits the use of the technique. To overcome this shortcoming we developed a tool, written in Java, which supports subgroup discovery in a post-processing step. The tool engages the analyst in an interactive process of subgroup discovery by means of a graphical interface with well defined statistical grounds, where domain knowledge can be used during the identification of such subgroups amid the population. We show a case study to analyze the results of students in a large scale university admission examination.","Title: Minimalist Architecture to Generate Embedded System Web User Interfaces.\nYear: 2013\n\nAbstract: This paper presents a new architecture to. semi-automatically generate Web user interfaces for Embedded Systems designed using IOPT Petri Net models. The user interfaces can be used to remotely control, monitor and debug embedded systems using a standard Web Browser. The proposed architecture takes advantage of the distributed nature of the Internet to store all static user interface data and software on third-party Web services (the Cloud), and execute the user-interface code on the user's Web Browser. A simplified protocol is proposed to enable remote control, status-monitoring, debugging and step-by-step execution, minimizing resource consumption on the physical embedded devices, including processing load, memory and communication bandwidth. As the user interface data and code are kept on third-party Web services, these resources can be shared among multiple embedded device units, and the hardware requirements to implement the devices can be simplified, leading to reduced cost solutions. To prevent down-time due to network problems or server failures, a fault-tolerant topology is suggested. The distributed architecture is transparent to end-users, observing just a Web interface for an embedded device on the other side of an Internet URL.","Title: Reading the web with learned syntactic-semantic inference rules\nYear: 2012\n\nAbstract: We study how to extend a large knowledge base (Freebase) by reading relational information from a large Web text corpus. Previous studies on extracting relational knowledge from text show the potential of syntactic patterns for extraction, but they do not exploit background knowledge of other relations in the knowledge base. We describe a distributed, Web-scale implementation of a path-constrained random walk model that learns syntactic-semantic inference rules for binary relations from a graph representation of the parsed text and the knowledge base. Experiments show significant accuracy improvements in binary relation prediction over methods that consider only text, or only the existing knowledge base.","Title: Improving Transform Domain Wyner-Ziv Video Coding Performance\nYear: 2006\n\nAbstract: Distributed video coding (DVC) is a new video coding paradigm based on two key Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. A particular case of DVC, the so-called Wyner-Ziv coding, deals with lossy source coding with side information at the decoder and enables a flexible allocation of complexity between the encoder and the decoder. This paper proposes an improved transform domain Wyner-Ziv video codec including: 1) the integer block-based transform defined in the H.264/MPEG-4 AVC standard, 2) a quantizer with a symmetrical interval around zero for AC coefficients, and a quantization step size adjusted to the transform coefficient bands dynamic range, and finally and 3) advanced frame interpolation for side information generation. The combination of these tools brings significant rate-distortion (RD) gains regarding the state-of-the-art results available in the literature.","Title: Automatic video summarization based on MPEG-7 descriptions\nYear: 2004\n\nAbstract: The ever-growing amount of audiovisual content available has raised the need to develop systems allowing each of us to consume the information considered ‘essential’, adapted to our tastes, our preferences, our time and also to our capacities of receiving, consuming and storing that information. In other words, there is an increasing need to develop systems able to automatically summarize audiovisual information. This paper proposes a novel query-based summary creation mechanism using a relevance metric and a constraints schema implemented in the context of an automatic video summarization system based on MPEG-7 descriptions. In the context of the same system, this paper also proposes a human skin filter allowing to build summaries based on the presence or absence of human skin. This skin colour filter is based solely on the MPEG-7 Dominant Colour descriptor, which means that the content is skin filtered with a rather small amount of processing, without accessing and processing the video data.","Title: Document expansion for speech retrieval\nYear: 1999\n\nAbstract: Advances in automatic speech recognition allow us to search large speech collections using traditional information retrieval methods. The problem of \"aboutness\" for documents - is a document about a certain concept - has been at the core of document indexing for the entire history of IR. This problem is more difficult for speech indexing since automatic speech transcriptions often contain mistakes. In this study we show that document expansion can be successfully used to alleviate the effect of transcription mistakes on speech retrieval. The loss of retrieval effectiveness due to automatic transcription errors can be reduced by document expansion from 15-27% relative to retrieval from human transcriptions to only about 7-13%, even for automatic transcriptions with word error rates as high as 65%. For good automatic transcriptions (25% word error rate), retrieval effectiveness with document expansion is indistinguishable from retrieval from human transcriptions. This makes speech retrieval from automatic transcriptions, even poor ones, competitive with retrieval from perfect transcriptions.","Title: Exact Convex Confidence-Weighted Learning\nYear: 2008\n\nAbstract: Confidence-weighted (CW) learning (6), an online learning method for linear clas- sifiers, maintains a Gaussian distributions over weight vectors, with a covariance matrix that represents uncertainty about weights and correlations. Confidence constraints ensure that a weight vector drawn from the hypothesis distribution correctly classifies examples with a specified probability. Within this framework, we derive a new convex form of the constraint and analyze it in the mistake bound model. Empirical evaluation with both synthetic and text data shows our version of CW learning achieves lower cumulative and out-of-sample errors than commonly used first-order and second-order online methods.","Title: Fast Mvc Prediction Structure Selection For Interactive Multiview Video Streaming\nYear: 2013\n\nAbstract: Multiview Video Coding (MVC) has been developed to efficiently compress a set of camera views by exploiting the spatial, temporal and interview correlations among images of the same scene. However, the resulting compressed data has a lot of prediction coding dependencies, which may not suit interactive multiview video streaming (IMVS) systems, where only one view is requested at a time by the end-user. This paper proposes a fast selection mechanism for effective interview prediction structure (PS) in IMVS while minimizing the point-to-point transmission rate, given some storage and visual distortion constraints, and a user interactive behavior model. Simulation results show that our novel fast MVC PS selection algorithm has high efficiency with low computational complexity that is reduced by more than 40% in comparison to the exhaustive searching benchmark.","Title: Quadratic Modeling Rate Control In The Emerging Hevc Standard\nYear: 2012\n\nAbstract: The High Efficiency Video Coding (HEVC) standardization project mainly aims at improving the compression efficiency beyond the state-of-the-art H. 264/AVC standard for high and ultra high definition video contents. The HEVC codec reference software, still under development, encodes video content using a fixed quantization step, thus leading to a variable bitrate stream which may not be suitable for the many multimedia applications where a constant bandwidth is required. Therefore, a rate control algorithm must be integrated in the HEVC codec taking into account that the novel coding tools further reduce the bitrate associated to texture data while increase the bitrate associated to the auxiliary information, e. g. motion vectors and coding modes. In this context, this paper studies the integration of a quadratic modeling rate control algorithm in the HEVC codec. Experimental results reveal that the rate control enabled HEVC codec provides a lower rate-distortion performance regarding a fixed quantization step HEVC codec, notably spending up to 20.12% more bitrate for the same objective quality. However, the integrated rate control algorithm offers lower bitrate fluctuations along the video contents than the HEVC codec with fixed quantization step.","Title: Refining side information for improved transform domain Wyner-Ziv video coding\nYear: 2009\n\nAbstract: Wyner-Ziv (WZ) video coding is a particular case of distributed video coding, which is a recent video coding paradigm based on the Slepian-Wolf and WZ theorems. Contrary to available prediction-based standard video codecs, WZ video coding exploits the source statistics at the decoder, allowing the development of simpler encoders. Until now, WZ video coding did not reach the compression efficiency performance of conventional video coding solutions, mainly due to the poor quality of the side information, which is an estimate of the original frame created at the decoder in the most popular WZ video codecs. In this context, this paper proposes a novel side information refinement (SIR) algorithm for a transform domain WZ video codec based on a learning approach where the side information is successively improved as the decoding proceeds. The results show significant and consistent performance improvements regarding state-of-the-art WZ and standard video codecs, especially under critical conditions such as high motion content and long group of pictures sizes.","Title: Intelligent email: reply and attachment prediction\nYear: 2008\n\nAbstract: We present two prediction problems under the rubric of Intelligent Email that are designed to support enhanced email interfaces that relieve the stress of email overload. Reply prediction alerts users when an email requires a response and facilitates email response management. Attachment prediction alerts users when they are about to send an email missing an attachment or triggers a document recommendation system, which can catch missing attachment emails before they are sent. Both problems use the same underlying email classification system and task specific features. Each task is evaluated for both single-user and cross-user settings.","Title: Improving scalable video coding performance with decoder side information\nYear: 2013\n\nAbstract: In a heterogeneous landscape of networks, devices and consumption environments, scalability is one of the most important video coding features. To achieve higher scalable video compression efficiency, this paper proposes a novel scalable video coding framework based on predictive video coding but also exploiting some additional decoder side information. The side information is estimated at both encoder and decoder using a motion compensated temporal interpolation technique, commonly used in distributed video coding solutions. To improve the B-slices compression efficiency, the side information independently created at each coding layer, notably the base and enhancement layers, is inserted in the corresponding layer decoded picture buffer to be exploited as an additional reference frame in the scalable predictive coding process. Experimental results have shown significant compression efficiency gains, notably up to around 3.5% in bitrate savings regarding the state-of-the-art SVC standard.","Title: Low Complexity Deblocking Filter Perceptual Optimization For The Hevc Codec\nYear: 2011\n\nAbstract: The compression efficiency of the state-of-art H.264/AVC video coding standard must be improved to accommodate the compression needs of high definition videos. To this end, ITU and MPEG started a new standardization project called High Efficiency Video Coding. The video codec under development still relies on transform domain quantization and includes the same in-loop deblocking filter adopted in the H.264/AVC standard to reduce quantization blocking artifacts. This deblocking filter provides two offsets to vary the amount of filtering for each image area. This paper proposes a perceptual optimization of these offsets based on a quality metric able to quantify the blocking artifacts impact on the perceived video quality. The proposed optimization involves low computational complexity and provides quality improvements with respect to a non-perceptually optimized H.264/AVC deblocking filter. Moreover, the proposed optimization allows up to 92% of complexity reduction regarding a brute force perceptual optimization which exhaustively tests all the possible offsets values.","Title: Relating probabilistic grammars and automata\nYear: 1999\n\nAbstract: Both probabilistic context-free grammars (PCFGs) and shift-reduce probabilistic pushdown automata (PPDAs) have been used for language modeling and maximum likelihood parsing. We investigate the precise relationship between these two formalisms, showing that, while they define the same classes of probabilistic languages, they appear to impose different inductive biases.","Title: Case-factor diagrams for structured probabilistic modeling\nYear: 2004\n\nAbstract: We introduce a probabilistic formalism subsuming Markov random fields of bounded tree width and probabilistic context free grammars. Our models are based on a representation of Boolean formulas that we call case-factor diagrams (CFDs). CFDs are similar to binary decision diagrams (BDDs) but are concise for circuits of bounded tree width (unlike BDDs) and can concisely represent the set of parse trees over a given string under a given context free grammar (also unlike BDDs). A probabilistic model consists of a CFD defining a feasible set of Boolean assignments and a weight (or cost) for each individual Boolean variable. We give an inside-outside algorithm for simultaneously computing the marginal of each Boolean variable, and a Viterbi algorithm for finding the mininum cost variable assignment. Both algorithms run in time proportional to the size of the CFD.","Title: MPEG-4: Why, what, how and when?\nYear: 2000\n\nAbstract: The MPEG-4 Version 1 standard has been recently finalized. Since MPEG-4 adopted an object-based audiovisual representation model with hyperlinking and interaction capabilities and supports both natural and synthetic content, it is expected that this standard will become the information coding playground for future multimedia applications. This paper intends to give an overview on the MPEG-4 motivations, objectives, achievements, process and workplan, providing a stimulating starting point for more detailed reading. (C) 1999 Elsevier Science B.V. All rights reserved.","Title: Automated gene-model curation using global discriminative learning.\nYear: 2012\n\nAbstract: Gene-model curation creates consensus gene models by combining multiple sources of protein-coding evidence that may be incomplete or inconsistent. To date, manual curation still produces the highest quality models. However, manual curation is too slow and costly to be completed even for the most important organisms. In recent years, machine-learned ensemble gene predictors have become a viable alternative to manual curation. Current approaches make use of signal and genomic region consistency among sources and some voting scheme to resolve conflicts in the evidence. As a further step in that direction, we have developed eCRAIG (ensemble CRAIG), an automated curation tool that combines multiple sources of evidence using global discriminative training. This allows efficient integration of different types of genomic evidence with complex statistical dependencies to maximize directly annotation accuracy. Our method goes beyond previous work in integrating novel non-linear annotation agreement features, as well as combinations of intrinsic features of the target sequence and extrinsic annotation features.We achieved significant improvements over the best ensemble predictors available for Homo sapiens, Caenorhabditis elegans and Arabidopsis thaliana. In particular, eCRAIG achieved a relative mean improvement of 5.1% over Jigsaw, the best published ensemble predictor in all our experiments.The source code and datasets are both available at http://www.seas.upenn.edu/abernal/ecraig.tgz.","Title: Intelligent email: aiding users with AI\nYear: 2008\n\nAbstract: Email occupies a central role in the modern workplace. This has led to a vast increase in the number of email messages that users are expected to handle daily. Furthermore, email is no longer simply a tool for asynchronous online communication-email is now used for task management, personal archiving, as well both synchronous and asynchronous online communication (Whittaker and Sidner 1996). This explosion can lead to .. email overload\"-many users are overwhelmed by the large quantity of information in their mailboxes. In the human--computer interaction community, there has been much research on tackling email overload. Recently, similar efforts have emerged in the artificial intelligence (AI) and machine learning communities to form an area of research known as intelligent email. In this paper, we take a user-oriented approach to applying AI to email. We identify enhancements to email user interfaces and employ machine learning techniques to support these changes. We focus on three tasks-summary keyword generation, reply prediction and attachment prediction-and summarize recent work in these areas.","Title: A New Fast Motion Estimation And Mode Decision Algorithm For H.264 Depth Maps Encoding In Free Viewpoint Tv\nYear: 2011\n\nAbstract: In this paper, we consider a scenario where 3D scenes are modeled through a View+Depth representation. This representation is to be used at the rendering side to generate synthetic views for free viewpoint video. The encoding of both type of data (view and depth) is carried out using two H.264/AVC encoders. In this scenario we address the reduction of the encoding complexity of depth data. Firstly, an analysis of the Mode Decision and Motion Estimation processes has been conducted for both view and depth sequences, in order to capture the correlation between them. Taking advantage of this correlation, we propose a fast mode decision and motion estimation algorithm for the depth encoding. Results show that the proposed algorithm reduces the computational burden with a negligible loss in terms of quality of the rendered synthetic views. Quality measurements have been conducted using the Video Quality Metric.","Title: MPEG-A: Multimedia Application Formats\nYear: 2005\n\nAbstract: MPEG standards, instrumental in shaping the multimedia landscape since the early 1990s, are taking another step forward with MPEG-A, which specifies multimedia application formats. MAFs are essentially superformats that combine selected technology components from MPEG (and other) standards to provide greater application interoperability, which helps satisfy users' growing need for better-integrated multimedia solutions.","Title: Intensional Verbs Without Type-Raising or Lexical Ambiguity.\nYear: 1994\n\nAbstract: We present an analysis of the semantic interpretation of intensional verbs\nsuch as seek that allows them to take direct objects of either individual or\nquantifier type, producing both de dicto and de re readings in the quantifier\ncase, all without needing to stipulate type-raising or quantifying-in rules.\nThis simple account follows directly from our use of logical deduction in\nlinear logic to express the relationship between syntactic structures and\nmeanings. While our analysis resembles current categorial approaches in\nimportant ways, it differs from them in allowing the greater type flexibility\nof categorial semantics while maintaining a precise connection to syntax. As a\nresult, we are able to provide derivations for certain readings of sentences\nwith intensional verbs and complex direct objects that are not derivable in\ncurrent purely categorial accounts of the syntax-semantics interface. The\nanalysis forms a part of our ongoing work on semantic interpretation within the\nframework of Lexical-Functional Grammar.","Title: Very low bit-rate audio-visual applications\nYear: 1996\n\nAbstract: Very low bit-rate audio-visual applications have recently become a hot topic in image communications. The recognition that audio-visual applications at very low bit-rates are potentially very interesting to consumers, and hence manufacturers and service providers, led to the start of considerable standardisation efforts. The most important standardisation efforts in the very low bit-rate area are taking place within ITU-T Study Group 15 and ISO/IEC JTC1/SC29/WG11 (MPEG). This paper intends to review the current situation in the standardisation of very low bit-rate audio-visual applications, and to provide a list of important and interesting very low bit-rate audio-visual applications, clustered according to their technical features while describing their main requirements.","Title: Weighted rational transductions and their application to human language processing\nYear: 1994\n\nAbstract: We present the concepts of weighted language, transduction and automaton from algebraic automata theory as a general framework for describing and implementing decoding cascades in speech and language processing. This generality allows us to represent uniformly such information sources as pronunciation dictionaries, language models and lattices, and to use uniform algorithms for building decoding stages and for optimizing and combining them. In particular, a single automata join algorithm can be used either to combine information sources such as a pronunciation dictionary and a context-dependency model during the construction of a decoder, or dynamically during the operation of the decoder. Applications to speech recognition and to Chinese text segmentation will be discussed.","Title: Multimedia Standards: Present and Future\nYear: 1999\n\nAbstract: Multimedia services and applications, from videotelepnony and digital television to multimedia databases and 3D virtual environments, are undoubtedly among the novelties of the end of the century, already announcing the big changes that will characterize the XXIst century society.With the explosion of new techniques and methods in all scientific areas related to multimedia, standardization bodies assume a fundamental role of coordination and even steering thus avoiding the birth of a chaotic multimedia market with all its negative effects. \"A standard should be like a contract. A process by which individuals recognize the advantage of doing certain things in an agreed way and codify that agreement in a contract, we compromise between what we want to do and what others want to do. Though it constraines our freedom, we usually enter into such an agreement because the perceived advantages exceed the perceived disadvantages\". In conclusion, the main advantage of a standard is the increased interoperability, and the possibilty to substantially increase the number of users due to the existence of a generalized agreement.","Title: Domain adaptation with structural correspondence learning\nYear: 2006\n\nAbstract: Discriminative learning methods are widely used in natural language processing. These methods work best when their training and test data are drawn from the same distribution. For many NLP tasks, however, we are confronted with new domains in which labeled data is scarce or non-existent. In such cases, we seek to adapt existing models from a resource-rich source domain to a resource-poor target domain. We introduce structural correspondence learning to automatically induce correspondences among features from different domains. We test our technique on part of speech tagging and show performance gains for varying amounts of source and target training data, as well as improvements in target domain parsing accuracy using our improved tagger.","Title: Learning Based Decoding Approach For Improved Wyner-Ziv Video Coding\nYear: 2012\n\nAbstract: Wyner-Ziv (WZ) video coding compression efficiency depends critically both on the side information (SI) quality and the correlation noise model (CNM) accuracy. In this context, this paper proposes a learning based decoding approach for transform domain WZ video coding, notably in the context of the following techniques: i) fractional-pixel motion field learning to define the relevance of the SI block candidates, and ii) CNM parameter learning. Experimental results show the proposed learning approach brings consistent RD performance improvements, with coding gains up to 3.9 dB regarding the state-of-the-art DISCOVER WZ video codec for a GOP size of 8.","Title: Probability Updating For Decoder And Encoder Rate Control Turbo Based Wyner-Ziv Video Coding\nYear: 2010\n\nAbstract: In Wyner-Ziv video coding (WZVC), powerful error correcting codes must be used to achieve high compression efficiency; turbo codes are the most commonly used error correcting codes in WZVC. To improve the turbo coding performance in the context of WZVC, this paper proposes a probability updating technique (PUT) acting as an outer loop of the common turbo decoding operation. Whenever a turbo decoded bitplane is not error-free, the proposed technique attempts to correct bitplane errors by updating the correlation noise probabilities for the most likely in error bits, followed by turbo re-decoding. The new tool is evaluated both in the context of encoder rate control (ERC) and decoder rate control (DRC) turbo based WZVC scenarios with average overall PSNR gains up to about 0.5 dB in ERC and average WZ rate savings up to about 6% in DRC.","Title: Image segmentation towards new image representation methods\nYear: 1995\n\nAbstract: Very low bit-rate video coding has recently become one of the most important areas of image communication and a large variety of applications have already been identified. Since conventional approaches are reaching a saturation point, in terms of coding efficiency, a new generation of video coding techniques, aiming at a deeper \"understanding\" of the image, is being studied. In this context, image analysis, particularly the identification of objects or regions in images (segmentation), is a very important step. This paper describes a segmentation algorithm based on split and merge. Images are first simplified using mathematical morphology operators, which eliminate perceptually less relevant details. The simplified image is then split according to a quad tree structure and the resulting regions are finally merged in three steps: merge, elimination of small regions and control of the number of regions.","Title: MPEG multimedia standards: evolution and future developments\nYear: 2007\n\nAbstract: Multimedia communications play a growing role in the every day's life of modern societies. Until recently, and except for broadcast television and radio, voice was still the sole communication mechanism. However, the diffusion of digital processing algorithms and hardware has brought images, music, and video into everyday life. The availability of open standards (such as JPEG, MPEG-X Audio and Video, H.26X) has had a major impact on this progression, notably due to the easy interoperability. Such standards have made the creation, and communication of (digital) data aimed at our most important senses, sight and hearing, simple, inexpensive and commonplace. With time, multimedia standards have addressed a growing set of fields from coding and metadata to rights management and content adaptation, following the increasing (functional and technical) complexity of multimedia applications. Since MPEG standards have played a key role in the progress of the multimedia landscape, this tutorial will provide an evolutional overview of MPEG standards, discussing and explaining why certain choices were made, and thus a certain vision of the multimedia world was followed. Moreover this tutorial will specifically address the most recent MPEG standards, notably MPEG-21, MPEG-4 AVC, SVC and MVC, and finally MPEG-A.","Title: MPEG-4: Context and objectives\nYear: 1997\n\nAbstract: The MPEG-4 audiovisual representation standard currently under development addresses the needs and requirements, arising from the increasing availability of audiovisual content in digital form. It goes beyond digitizing linear audio and video, specifying a description of digital material in the form of 'objects', that can be flexibly and interactively used and re-used. This paper describes the developments that make MPEG-4 necessary ('Why'), what MPEG-I does to address the new needs ('What'), and gives an overview of how the standard is developed ('How').","Title: Automatic Generation of Run-Time Monitoring Capabilities to Petri Nets Based Controllers with Graphical User Interfaces\nYear: 2011\n\nAbstract: The growing processing power available in FPGAs and other embedded platforms, associated with the ability to generate high resolution images and interface with pointing devices, opened the possibility to create devices with sophisticated user interfaces. This paper presents an innovative tool to automatically generate debug, diagnostic and monitoring graphical interfaces to be integrated in embedded systems designed using Petri net based controllers. Devices powered with the new debug and diagnostic interfaces benefit from lower maintenance costs and simplified failure diagnostic capabilities, leading to longer product life cycles with the corresponding environmental and sustainability gains. To demonstrate the validity of the tools proposed, the paper presents an application example for a Car Parking controller, including results on a working prototype.","Title: Wyner-Ziv Video Coding: A Review Of The Early Architectures And Further Developments\nYear: 2008\n\nAbstract: In 2002, the video coding community faced the emergence of a new video coding paradigm, the so-called Wyner-Ziv video coding, which was represented by two early solutions designed by the Stanford University and the University of California, Berkeley research teams. This paper intends to briefly review, and compare these two early Wyner-Ziv video coding solutions, notably from the functional point of view. Moreover, this paper reviews some important developments of the Stanford Wyner-Ziv coding architecture, which has become the most popular in the literature.","Title: Adaptive shape and texture intra refreshment schemes for improved error resilience in object-based video coding\nYear: 2004\n\nAbstract: Video encoders may use several techniques to improve error resilience. In particular, for video encoders that rely on predictive (inter) coding to remove temporal redundancy, intra coding refreshment is especially useful to stop temporal error propagation when errors occur in the transmission or storage of the coded streams, since these errors may cause the decoded quality to decay very rapidly. In the context of object-based video coding, intra coding refreshment can be applied to both the shape and texture data. In this paper, novel shape and texture intra refreshment schemes are proposed which can be used by object-based video encoders, such as MPEG-4 video encoders, independently or combined. These schemes allow to adaptively determine when the shape and texture of the various video objects in a scene should be refreshed in order to maximize the decoded video quality for a certain total bit rate.","Title: Distributed Latent Variable Models of Lexical Co-occurrences.\nYear: 2005\n\nAbstract: Low-dimensional representations for lex- ical co-occurrence data have become in- creasingly important in alleviating the sparse data problem inherent in natural lan- guage processing tasks. This work presents a distributed latent variable model for in- ducing these low-dimensional representa- tions. The model takes inspiration from both connectionist language models (1, 16) and latent variable models (13, 9). We give results which show that the new model sig- nificantly improves both bigram and trigram models.","Title: Distributed Monoview and Multiview Video Coding\nYear: 2007\n\nAbstract: Growing percentage of the world population now uses image and video coding technologies on a regular basis. These technologies are behind the success and quick deployment of services and products such as digital pictures, digital television, DVDs, and Internet video communications. Today's digital video coding paradigm represented by the ITU-T and MPEG standards mainly relies on a hybrid of block-...","Title: The Need for Open Source Software in Machine Learning\nYear: 2007\n\nAbstract: Open source tools have recently reached a level of maturity which makes them suitable for building large-scale real-world systems. At the same time, the field of machine learning has developed a large body of powerful learning algorithms for diverse applications. However, the true potential of these methods is not used, since existing implementations are not openly shared, resulting in software with low usability, and weak interoperability. We argue that this situation can be significantly improved by increasing incentives for researchers to publish their software under an open source model. Additionally, we outline the problems authors are faced with when trying to publish algorithmic implementations of machine learning methods. We believe that a resource of peer reviewed software accompanied by short articles would be highly valuable to both the machine learning and the general scientific community.","Title: Multimedia Retrieval and Delivery: Essential Metadata Challenges and Standards\nYear: 2008\n\nAbstract: Multimedia information retrieval (MIR) and delivery plays an important role in many application domains due to the increasing need to identify, filter, and manage growing amounts of data, notably multimedia information. To efficiently manage and exchange multimedia information, interoperability between coded data and metadata is required and standardization is central to achieving the necessary le...","Title: Automatic creation and evaluation of MPEG-7 compliant summary descriptions for generic audiovisual content\nYear: 2008\n\nAbstract: Today's world is characterized by the increasing availability of audiovisual content, created in many application domains and, thus, with rather different semantic characteristics. Audiovisual content is easily acquired, produced, processed, coded, stored and distributed, progressively making more important the ability for users to selectively consume the large amounts of content available. Automatic audiovisual summarization is a technology playing a major role towards facilitating the user's effective consumption of large amounts of audiovisual data in a reduced amount of time as time is getting more and more precious and scarce. This paper proposes an automatic summarization system for generic audiovisual content based on MPEG-7 compliant summary descriptions. To evaluate the quality of the created summaries, a user evaluation methodology was designed, and applied with promising results, showing that the developed application is able to summarize with success generic audiovisual content, especially high action content. The main novelty of this paper is related to the usage of the MPEG-7 summarization tools in combination with an arousal-based audiovisual summarization model, and to the novel user evaluation methodology and study.","Title: Perceptually driven video error protection using a distributed source coding approach\nYear: 2014\n\nAbstract: In video communication systems, the video signals are typically compressed and sent to the decoder through an error-prone transmission channel that may corrupt the compressed signal, causing the degradation of the final decoded video quality. In this context, it is possible to enhance the error resilience of typical predictive video coding schemes using as inspiration principles and tools from an alternative video coding approach, the so-called Distributed Video Coding (DVC), based on the Distributed Source Coding (DSC) theory. Further improvements in the decoded video quality after error-prone transmission may also be obtained by considering the perceptual relevance of the video content, as distortions occurring in different regions of a picture have a different impact on the user's final experience. In this context, this paper proposes a Perceptually Driven Error Protection (PDEP) video coding solution that enhances the error resilience of a state-of-the-art H.264/AVC predictive video codec using DSC principles and perceptual considerations. To increase the H.264/AVC error resilience performance, the main technical novelties brought by the proposed video coding solution are: (i) design of an improved compressed domain perceptual classification mechanism; (ii) design of an improved transcoding tool for the DSC-based protection mechanism; and (iii) integration of a perceptual classification mechanism in an H.264/AVC compliant codec with a DSC-based error protection mechanism. The performance results obtained show that the proposed PDEP video codec provides a better performing alternative to traditional error protection video coding schemes, notably Forward Error Correction (FEC)-based schemes.","Title: Analysis for Video Coding: Moving It from the Encoder to the Decoder\nYear: 2008\n\nAbstract: Video coding has a major importance in modern multimedia communications, applications and products as it is a core technology for their technical and economical deployment with success. This paper presents and compares the conventional, encoder prediction based video coding paradigm versus the novel, decoder estimation based video coding paradigm, especially from a video analysis for coding perspective. Besides the basic concepts and tools, the novel benefits, problems and challenges will be compared and discussed in the context of the most popular Wyner-Ziv video coding architecture.","Title: Confidence-weighted linear classification for text categorization\nYear: 2012\n\nAbstract: Confidence-weighted online learning is a generalization of margin-based learning of linear classifiers in which the margin constraint is replaced by a probabilistic constraint based on a distribution over classifier weights that is updated online as examples are observed. The distribution captures a notion of confidence on classifier weights, and in some cases it can also be interpreted as replacing a single learning rate by adaptive per-weight rates. Confidence-weighted learning was motivated by the statistical properties of natural-language classification tasks, where most of the informative features are relatively rare. We investigate several versions of confidence-weighted learning that use a Gaussian distribution over weight vectors, updated at each observed example to achieve high probability of correct classification for the example. Empirical evaluation on a range of text-categorization tasks show that our algorithms improve over other state-of-the-art online and batch methods, learn faster in the online setting, and lead to better classifier combination for a type of distributed training commonly used in cloud computing.","Title: SCAN: designing and evaluating user interfaces to support retrieval from speech archives\nYear: 1999\n\nAbstract: Previous examinations of search in textual archives have assumed that users first retrieve a ranked set of documents relevant to their query, and then visually scan through these documents, to identify the information they seek. While document scanning is possible in text, it is much more laborious in speech archives, due to the inherently serial nature of speech. Yet, in developing tools for speech access, little attention has so far been paid to users' problems in scanning and extracting information from within \"speech documents\". We demonstrate the extent of these problems in two user studies. We show that users experience seven problems with local navigation in extracting relevant information from within \"speech documents\". Based on these results, we propose a new user interface (UI) design paradigm: What You See Is (Almost) What You Hear, (WYSIAWYH) - a multimodal method for accessing speech archives. This paradigm presents a visual analogue to the underlying speech, enabling visual scanning for effective local navigation. We empirically evaluate a UI based on this paradigm. We compare our WYSIAWYH UI with a visual \"tape recorder\", in relevance ranking, fact-finding, and summarization tasks involving broadcast news data. Our findings indicate that an interface supporting local navigation multimodally helps relevance ranking and fact-finding, but not summarization. We analyze the reasons for system success and identify outstanding research issues in UI design for speech archives.","Title: Sparsity in Dependency Grammar Induction\nYear: 2010\n\nAbstract: A strong inductive bias is essential in un- supervised grammar induction. We ex- plore a particular sparsity bias in de- pendency grammars that encourages a small number of unique dependency types. Specifically, we investigate sparsity-inducing penalties on the poste- rior distributions of parent-child POS tag pairs in the posterior regularization (PR) framework of Graça et al. (2007). In ex- periments with 12 languages, we achieve substantial gains over the standard expec- tation maximization (EM) baseline, with average improvement in attachment ac- curacy of 6.3%. Further, our method outperforms models based on a standard Bayesian sparsity-inducing prior by an av- erage of 4.9%. On English in particular, we show that our approach improves on several other state-of-the-art techniques.","Title: Structured Learning with Approximate Inference\nYear: 2007\n\nAbstract: In many structured prediction problems, the highest-scoring labeling is hard to compute exactly, leading to the use of approximate inference methods. However, when inference is used in a learning algorithm, a good approximation of the score may not be sufficient. We show in particular that learning can fail even with an approximate inference method with rigorous approximation guarantees. There are two reasons for this. First, approximate methods can effectively reduce the expres- sivity of an underlying model by making it impossible to choose parameters that reliably give good predictions. Second, approximations can respond to parameter changes in such a way that standard learning algorithms are misled. In contrast, we give two positive results in the form of learning bounds for the use of LP-relaxed inference in structured perceptron and empirical risk minimization settings. We argue that without understanding combinations of inference and learning, such as these, that are appropriately compatible, learning performance under approximate inference cannot be guaranteed.","Title: Semi-automated named entity annotation\nYear: 2007\n\nAbstract: We investigate a way to partially automate corpus annotation for named entity recognition, by requiring only binary decisions from an annotator. Our approach is based on a linear sequence model trained using a k-best MIRA learning algorithm. We ask an annotator to decide whether each mention produced by a high recall tagger is a true mention or a false positive. We conclude that our approach can reduce the effort of extending a seed training corpus by up to 58%.","Title: Video object relevance metrics for overall segmentation quality evaluation\nYear: 2006\n\nAbstract: Video object segmentation is a task that humans perform efficiently and effectively, but which is difficult for a computer to perform. Since video segmentation plays an important role for many emerging applications, as those enabled by the MPEG-4 and MPEG-7 standards, the ability to assess the segmentation quality in view of the application targets is a relevant task for which a standard, or even a consensual, solution is not available. This paper considers the evaluation of overall segmentation partitions quality, highlighting one of its major components: the contextual relevance of the segmented objects. Video object relevance metrics are presented taking into account the behaviour of the human visual system and the visual attention mechanisms. In particular, contextual relevance evaluation takes into account the context where an object is found, exploiting, for instance, the contrast to neighbours or the position in the image. Most of the relevance metrics proposed in this paper can also be used in contexts other than segmentation quality evaluation, such as object-based rate control algorithms, description creation, or image and video quality evaluation.","Title: Perspective transform motion modeling for improved side information creation.\nYear: 2013\n\nAbstract: Abstract The distributed video coding (DVC) paradigm is based on two well-known information theory results: the Slepian-Wolf and Wyner-Ziv theorems. In a DVC codec, the video signal correlation is mostly exploited at the decoder, providing a flexible distribution of the computational complexity between the encoder and the decoder and error robustness to channel errors. To exploit the temporal correlation, an estimate of the original frame to code, well-known as side information, is typically created at the decoder. One popular approach to side information creation is to perform frame interpolation using a translational motion model derived from already decoded frames. However, this translational model fails to estimate complex camera motions, such as zooms and rotations, and is not accurate enough to estimate the true trajectories of scene objects. In this paper, a new side information creation framework integrating perspective transform motion modeling is proposed. This solution is able to better locally track the trajectories and deformations of each object and increase the accuracy of the overall side information estimation process. Experimental results show peak signal-to-noise ratio gains of up to 1 dB in side information quality and up to 0.5 dB in rate-distortion performance for some video sequences regarding state-of-the-art alternative solutions.","Title: The Unreasonable Effectiveness of Data\nYear: 2009\n\nAbstract: Problems that involve interacting with humans, such as natural language understanding, have not proven to be solvable by concise, neat formulas like F = ma. Instead, the best approach appears to be to embrace the complexity of the domain and address it by harnessing the power of data: if other humans engage in the tasks and generate large amounts of unlabeled, noisy data, new algorithms can be used to build high-quality models from the data.","Title: A flexible side information generation framework for distributed video coding\nYear: 2010\n\nAbstract: One of the most efficient approaches to generate the side information (SI) in distributed video codecs is through motion compensated\n frame interpolation where the current frame is estimated based on past and future reference frames. However, this approach\n leads to significant spatial and temporal variations in the correlation noise between the source at the encoder and the SI\n at the decoder. In such scenario, it would be useful to design an architecture where the SI can be more robustly generated\n at the block level, avoiding the creation of SI frame regions with lower correlation, largely responsible for some coding\n efficiency losses. In this paper, a flexible framework to generate SI at the block level in two modes is presented: while\n the first mode corresponds to a motion compensated interpolation (MCI) technique, the second mode corresponds to a motion\n compensated quality enhancement (MCQE) technique where a low quality Intra block sent by the encoder is used to generate the\n SI by doing motion estimation with the help of the reference frames. The novel MCQE mode can be overall advantageous from\n the rate-distortion point of view, even if some rate has to be invested in the low quality Intra coding blocks, for blocks\n where the MCI produces SI with lower correlation. The overall solution is evaluated in terms of RD performance with improvements\n up to 2 dB, especially for high motion video sequences and long Group of Pictures (GOP) sizes.","Title: Reading the markets: forecasting public opinion of political candidates by news analysis\nYear: 2008\n\nAbstract: Media reporting shapes public opinion which can in turn influence events, particularly in political elections, in which candidates both respond to and shape public perception of their campaigns. We use computational linguistics to automatically predict the impact of news on public perception of political candidates. Our system uses daily newspaper articles to predict shifts in public opinion as reflected in prediction markets. We discuss various types of features designed for this problem. The news system improves market prediction over baseline market systems.","Title: Experiments in graph-based semi-supervised learning methods for class-instance acquisition\nYear: 2010\n\nAbstract: Graph-based semi-supervised learning (SSL) algorithms have been successfully used to extract class-instance pairs from large unstructured and structured text collections. However, a careful comparison of different graph-based SSL algorithms on that task has been lacking. We compare three graph-based SSL algorithms for class-instance acquisition on a variety of graphs constructed from different domains. We find that the recently proposed MAD algorithm is the most effective. We also show that class-instance extraction can be significantly improved by adding semantic information in the form of instance-attribute edges derived from an independently developed knowledge base. All of our code and data will be made publicly available to encourage reproducible research in this area.","Title: Similarity-based methods for word sense disambiguation\nYear: 1997\n\nAbstract: We compare four similarity-based estimation methods against back-off and maximum-likelihood estimation methods on a pseudo-word sense disambiguation task in which we controlled for both unigram and bigram frequency. The similarity-based methods perform up to 40% better on this particular task. We also conclude that events that occur only once in the training set have major impact on similarity-based estimates.","Title: Automatic MPEG-4 sprite coding--Comparison of integrated object segmentation algorithms\nYear: 2010\n\nAbstract: Sprite coding, as standardized in MPEG-4 Visual, can result in superior performance compared to common hybrid video codecs. We consider sprite coding, which significantly increases the objective as well as the subjective quality of coded video content. The main challenge of this approach is the segmentation of the foreground objects in a preprocessing step. We evaluate automatic object segmentation methods based on global motion estimation and background sprite generation. The objects are coded using the MPEG-4 Visual Main Profile and compared with the Advanced Simple Profile.","Title: Extrapolating side information for low-delay pixel-domain distributed video coding\nYear: 2005\n\nAbstract: Distributed Video Coding (DVC) is a new video coding approach based on the Wyner-Ziv theorem. Unlike most of the existing video codecs, each frame is encoded separately (either as a key-frame or a Wyner-Ziv frame) which results in a simpler and lighter encoder since complex operations like motion estimation are not performed. The previously decoded frames are used at the decoder to estimate the Wyner-Ziv frames – the frames are coded independently but jointly decoded. To have a low-delay codec, the side information frames (estimation of the Wyner-Ziv frames to be decoded) must be extrapolated from past frames. This paper proposes a robust extrapolation module to generate the side information based on motion field smoothening to provide improved performance in the context of a low-delay pixel-domain DVC codec.","Title: Using MPEG-7 for Generic Audiovisual Content Automatic Summarization\nYear: 2008\n\nAbstract: This paper proposes and evaluates a fully automatic summarization application for generic audiovisual based on MPEG-7 compliant hierarchical summary descriptions, which allows providing flexibility, low complexity, and interoperability. The novelty of this paper regards the exploitation of a three features, low-level arousal model to generate the summary metadata needed to instantiate MPEG-7 compliant summary descriptions with the advantages this brings in terms of interoperability. Moreover, a novel, solid performance evaluation methodology has been proposed and its application has been performed.","Title: Media Representation Standards for the New Millennium (Tutorial)\nYear: 2002\n\nAbstract: The fast evolution of digital technology in the last decade has deeply transformed the way by which information, notably visual information, is generated, processed, transmitted and stored. The need for standards comes from an essential requirement relevant for all applications involving communication between two or more parts: interoperability. Interoperability is thus the requirement expressing the user's dream of exchanging any type of information without any technical barriers, in the simplest way. Without a standard way to perform some of the operations involved in the communication process and to structure the data exchanged, easy interoperability between the terminals involved would be impossible. Having said that, it is clear that a standard should specify the minimum number of tools to guarantee interoperability since it is important that as many as possible non-normative technical zones exist, to allow the incorporation of technical advances, and thus to increase the life time of the standard, as well as to stimulate the industrial technical competition. The existence of a standard has also important economical implications since it allows the sharing of costs and investments and the acceleration of applications' deployment. Among the most relevant standardization achievements are those by ISO/MPEG and ITU-T for media representation, some of them developed in close collaboration such as MPEG-2/H.262. The ISO/MPEG standardization committee has been responsible for the successful MPEG-1 and MPEG-2 standards that have given rise to widely adopted commercial products and services, such as Video-CD, DVD, digital television, digital audio broadcasting (DAB) and MP3 (MPEG-1 Audio layer 3) players and recorders. More recently, the MPEG-4 standard is aimed to define an audiovisual coding standard to address the emerging needs of the communication, interactive and broadcasting service models as well as of the mixed service models resulting from their technological convergence. The MPEG-4 object-based representation approach where a scene is modelled as a composition of objects, both natural and synthetic, with which the user may interact, is at the heart of the MPEG-4 technology. With this new coding approach, the MPEG-4 standard opens new frontiers in the way users will play with, create, re-use, access and consume audiovisual content. Following the same vision underpinning MPEG-4, MPEG initiated after another standardization project addressing the problem of describing multimedia content to allow the quick and efficient searching, processing and filtering of various types of multimedia material: MPEG-7. The need for a powerful solution for quickly and efficiently identifying, searching, filtering, etc., various types of multimedia content of interest to the user, human or machine, using also non text-based technologies, directly follows from the urge to efficiently use the available multimedia content and the difficulty of doing so. Following the development of the standards mentioned above, MPEG acknowledged the lack of a \"big picture\" describing how the various elements building the infrastructure for the deployment of multimedia applications relate to each other or even if there are missing open standard specifications for some of these elements. To address this problem, MPEG started the MPEG-21 project, formally called \"Multimedia framework\" with the aim to understand if and how these various elements fit together, and to discuss which new standards may be required, if gaps in the infrastructure exist. Once this work has been carried out, new standards will be developed for the missing elements with the involvement of other bodies, where appropriate, and finally the existing and novel standards will be integrated in the MPEG- 21 multimedia framework. The MPEG-21 vision is thus to define an open multimedia framework to enable the transparent and augmented delivery and consumption of multimedia resources across a wide range of networks and devices used by different communities. The MPEG-21 multimedia framework will identify and define the key elements needed to support the multimedia value and delivery chain, as well as the relationships between and the operations supported by them. This open framework guarantees all content creators and service providers equal opportunities in the MPEG-21 enabled open market. This will also be to the benefit of the content consumers who get access to a large variety of contents in an interoperable manner. In a similar manner, ITU-T defined standards such as H.261 and H.263 for videotelephony and videoconference over different types of channels and it is now developing the so-called H.26L/JVT or MPEG-4 Advanced Video Coding (AVC) standard in collaboration with MPEG; this new standard should provide further significant improvements in terms of coding efficiency. These ITU-T/MPEG collaborations highlight the convergence of technologies for media representation, independently of the transmission and storage media and many times of the application and business models involved. This tutorial will address the evolution and current status in terms of media representation technologies and standards as well as the most relevant emerging developments.","Title: Content Adaptation: The Panacea for Usage Diversity?\nYear: 2003\n\nAbstract: The past decade has seen a variety of developments in the area of multimedia representation and communications and thus multimedia\n access. In particular, we are beginning to see delivery of all types of data for all types of users in all types of conditions.\n In a diverse and heterogeneous world, the delivery path for multimedia content to a multimedia terminal is not straightforward.\n The notion of Universal Multimedia Access (UMA) calls for the provision of different presentations of the same content/information,\n with more or less complexity, suiting the different usage environments (i.e., the context) in which the content will be consumed.\n ‘Universal’ applies here to the user location (anywhere) and time (anytime) but also to the content to be accessed (anything)\n even if that requires some adaptation to occur. Universal Multimedia Access requires a general understanding of personalization,\n involving not only the user’s needs and preferences, but also the user’s environment’s capabilities, e.g., the network characteristics,\n the terminal where the content will be consumed and the natural environment where a user is located, e.g., location, and temperature.\n In conclusion, with UMA content adaptation is proposed as the solution to bridge content authors and content consumers in\n the context of more and more diverse multimedia chains.","Title: Aggregate and mixed-order Markov models for statistical language processing\nYear: 1997\n\nAbstract: We consider the use of language models whose size and accuracy are intermedi- ate between different order n-gram models. Two types of models are studied in partic- ular. Aggregate Markov models are class- based bigram models in which the map- ping from words to classes is probabilis- tic. Mixed-order Markov models combine bigram models whose predictions are con- ditioned on different words. Both types of models are trained by Expectation- Maximization (EM) algorithms for maxi- mum likelihood estimation. We examine smoothing procedures in which these mod- els are interposed between different order n-grams. This is found to significantly re- duce the perplexity of unseen word combi- nations.","Title: Distributed Video Coding with multiple side information\nYear: 2009\n\nAbstract: Distributed Video Coding (DVC) is a new video coding paradigm which mainly exploits the source statistics at the decoder based on the availability of some decoder side information. The quality of the side information has a major impact on the DVC rate-distortion (RD) performance in the same way the quality of the predictions had a major impact in predictive video coding. In this paper, a DVC solution exploiting multiple side information is proposed; the multiple side information is generated by frame interpolation and frame extrapolation targeting to improve the side information of a single estimation mode. Compared with the best available single side information solutions, the proposed DVC solution with multiple side information robustly improves the RD performance for the set of test sequences.","Title: Distributed video coding: basics, main solutions and trends\nYear: 2009\n\nAbstract: After the great success of the predictive video coding approach, which led to a number of largely deployed MPEG and ITU-T standards, the video coding research community has been working on a new video coding paradigm, so-called distributed video coding (DVC), which is based on some Information Theory results from the 70s: the Slepian-Wolf and the Wyner-Ziv theorems. The first practical solutions have emerged around 2002 at the Stanford University and the University of California, Berkeley. This talk will address the basics, main solutions and trends on distributed video coding with especial emphasis on the Stanford DVC codec which has deserved a larger research investment. The rate-distortion (RD) performance of a state-of-the-art Stanford based DVC codec will be presented and benchmarked by the relevant alternative standard based video coding solutions. Finally, some trends on the DVC research will be discussed.","Title: Image Description and Retrieval Using MPEG-7 Shape Descriptors\nYear: 2000\n\nAbstract: The increasing amount of digital audiovisual information and the need to efficiently and effectively describe and retrieve this information as well as the big technological developments in the related domains have been acknowledged by MPEG (Moving Pictures Experts Group) by initiating a new work item, formally called \"Multimedia Content Description Interface\" but better known as MPEG-7. This paper will introduce the MPEG-7 standard, with special emphasis on the adopted shape descriptors: Curvature Scale Space and Zernike Moments. Finally, the description and retrieval mechanism based on the MPEG-7 shape descriptors developed will be presented.","Title: Efficient graph-based semi-supervised learning of structured tagging models\nYear: 2010\n\nAbstract: We describe a new scalable algorithm for semi-supervised training of conditional random fields (CRF) and its application to part-of-speech (POS) tagging. The algorithm uses a similarity graph to encourage similar n-grams to have similar POS tags. We demonstrate the efficacy of our approach on a domain adaptation task, where we assume that we have access to large amounts of unlabeled data from the target domain, but no additional labeled data. The similarity graph is used during training to smooth the state posteriors on the target domain. Standard inference can be used at test time. Our approach is able to scale to very large problems and yields significantly improved target domain accuracy.","Title: Joint rate control algorithm for low-delay MPEG-4 object- based video encoding\nYear: 2009\n\nAbstract: This paper proposes an improved rate control algorithm for jointly encoding multiple arbitrarily shaped video objects in the context of low-delay MPEG-4 compliant video coding. The algorithm provides adequate mechanisms for dealing with deviations between the ideal and the actual behavior of video scene encoders, notably: 1) compensation mechanisms (e.g., rate control decisions) that are able to track these deviations and compensate them to allow a stable and efficient operation of the encoder, and 2) adaptation mechanisms (e.g., estimation of model parameters) that are able to instantaneously represent the actual behavior of the encoder and its rate controller. The proposed solution efficiently allocates the available resources, i.e., target bit rate and bitstream buffer space, aiming at maximizing the average scene quality and minimizing quality fluctuations along time and among the various video objects. The results show that this solution outperforms the usual reference solutions, notably those specified in the rate control informative annex of the MPEG-4 visual standard.","Title: Motion-Based Shape Error Concealment For Object-Based Video\nYear: 2004\n\nAbstract: In this paper, air original inotion-based shape error concealment technique, especially useful for object-based video applications in error-prone environments Such as mobile networks, is proposed. It is assumed that the shape of the corrupted object at hand is in the form of a binary, alpha plane and some of the shape data is missing due to channel errors. To conceal the corrupted shape, the decoder starts by assuming that the alpha plane changes in consecutive time instants can be described by a global motion model. This way, based oil locally estimated global motion parameters, the decoder tries to conceal the corrupted alpha plane by global motion compensating till the shape data from the previous time instant. Then, Since not all alpha plane changes can be perfectly described by global motion, an additional local motion refinement is applied to deal with areas of the object that have significant motion.","Title: Answering web questions using structured data: dream or reality?\nYear: 2009\n\nAbstract: The question of which role structured data can play in Web search has been raised from the early days of the Web. On the one hand, structured data can be used to answer factual queries. On the other, large amounts of structured data can be used to better organize web-content and therefore to improve search on a wide range of queries.","Title: A theory of learning from different domains\nYear: 2010\n\nAbstract: Discriminative learning methods for classification perform well when training and test data are drawn from the same distribution. Often, however, we have plentiful labeled training data from a source domain but wish to learn a classifier which performs well on a target domain with a different distribution and little or no labeled training data. In this work we investigate two questions. First, under what conditions can a classifier trained from source data be expected to perform well on target data? Second, given a small amount of labeled target data, how should we combine it during training with the large amount of labeled source data to achieve the lowest target error at test time?We address the first question by bounding a classifier's target error in terms of its source error and the divergence between the two domains. We give a classifier-induced divergence measure that can be estimated from finite, unlabeled samples from the domains. Under the assumption that there exists some hypothesis that performs well in both domains, we show that this quantity together with the empirical source error characterize the target error of a source-trained classifier.We answer the second question by bounding the target error of a model which minimizes a convex combination of the empirical source and target errors. Previous theoretical work has considered minimizing just the source error, just the target error, or weighting instances from the two domains equally. We show how to choose the optimal combination of source and target error as a function of the divergence, the sample sizes of both domains, and the complexity of the hypothesis class. The resulting bound generalizes the previously studied cases and is always at least as tight as a bound which considers minimizing only the target error or an equal weighting of source and target errors.","Title: The role of analysis in content-based video coding and indexing\nYear: 1998\n\nAbstract: L'expansion grandissante des technologies numériques dans de nombreux domaines, particulièrement les télécommunications et les loisirs (TV, cinéma), modifie de nos jours les paradigmes de production, distribution et consommation de l'information multimédia. De nouvelles applications exigeant une forte interaction basée sur le contenu sont imminentes, ce qui motive l'évolution des modèles utilisés pour la représentation des données, notamment pour le codage et l'indexation. Les futurs standards MPEG-4 et MPEG-7 sont la reconnaissance par l'industrie de ces nouveaux besoins. Cet article traite le problème de l'analyse vidéo pour le codage et l'indexation basé sur le contenu dans le contexte d'un paysage technologique changeant. Les objectifs et contraintes principaux de l'analyse vidéo sont identifiés, le rôle de l'interaction avec l'utilisateur est étudié et un certain nombre d'exemples d'applications sont décrits.","Title: Weighted finite-state transducers in speech recognition\nYear: 2002\n\nAbstract: We survey the use of weighted finite-state transducers (WFSTs) in speech recognition. We show that WFSTs provide a common and natural representation for hidden Markov models (HMMs), context-dependency, pronunciation dictionaries, grammars, and alternative recognition outputs. Furthermore, general transducer operations combine these representations flexibly and efficiently. Weighted determinization and minimization algorithms optimize their time and space requirements, and a weight pushing algorithm distributes the weights along the paths of a weighted transducer optimally for speech recognition. As an example, we describe a North American Business News (NAB) recognition system built using these techniques that combines the HMMs, full cross-word triphones, a lexicon of 40 000 words, and a large trigram grammar into a single weighted transducer that is only somewhat larger than the trigram word grammar and that runs NAB in real-time on a very simple decoder. In another example, we show that the same techniques can be used to optimize lattices for second-pass recognition. In a third example, we show how general automata operations can be used to assemble lattices from different recognizers to improve recognition performance.","Title: Musical slideshow: boosting user experience in photo presentation\nYear: 2011\n\nAbstract: With the advance of digital acquisition and storage technology, people got used to take photos at will and to record almost any event with (many) photos. However, large amounts of photos without appropriate organization for access and consumption raise several potential problems, reducing the users' quality of experience. Therefore, to facilitate an effective photo selection and organization process making the consumption process more enjoyable, it is useful to develop advanced image analysis and presentation tools, eventually integrating also some music content in a synchronized way, to further boost the photo presentation user experience. As people's time is getting more precious and scarce, the availability of applications able to automatically generate a musical slideshow as a pleasant way to consume large amounts of photos is highly desirable. In this context, this paper describes the context and motivation for the development of a musical slideshow application, the architecture designed and the entire signal processing flow implemented. To assess the performance of this multimedia application, a user evaluation methodology was designed and applied with promising results, showing that the developed application is able to create entertaining and efficient photo presentation experiences.","Title: Bit-Rate Control For Compression Of Video With Roi\nYear: 2004\n\nAbstract: In this paper, we present a compact survey of bit-rate control techniques winch can he used in design of video codecs equipped with online information on dynamical ROIs. We introduce the concept of zero rate increment on level sets in the context of linear data source models in p-domain. This approach enables a smooth image fidelity degradation on level sets for distance function from pixel to ROI. We focus in our examples on H.264/AVC which is the state-of-the-art in the video codec area.","Title: ATDD: An Algorithmic Tool for Domain Discovery in Protein Sequences\nYear: 2004\n\nAbstract: The problem of identifying sequence domains is essential for understanding protein function. Most current methods for protein domain identification rely on prior knowledge of homologous domains and construction of high quality multiple sequence alignments. With rapid accumulation of enormous data from genome sequencing, it is important to be able to automatically determine domain regions from a set of proteins solely based on sequence information. We describe a new algorithm for automatic protein domain detection that does not require multiple sequence alignment and differs from alignment based methods by allowing arbitrary rearrangements (both in relative ordering and distance) of the domains within the set of proteins under study. Moreover, our algorithm extracts domains by simply performing a comparative analysis of a given set of sequences, and no auxiliary information is required. The method views protein sequences as collections of overlapping fixed length blocks. A pair of blocks within a sequence gets a \"vote of confidence\" to be part of a domain if several other sequences have similar pairs of blocks at roughly the same distance from each other. Candidate domains are then identified by discovering regions in each protein sequence where most block pairs get strong votes of confidence. We applied our method on several test data sets with a fixed choice of parameters. To evaluate the results we computed sensitivity and specificity measures using SMART-derived domain annotations as a reference.","Title: A contour-based approach to binary shape coding using a multiple grid chain code\nYear: 2000\n\nAbstract: This paper presents a contour-based approach to efficiently code binary shape information in the context of object-based video coding. This approach meets some of the most important requirements identified for the MPEG-4 standard, notably efficient coding and low delay. The proposed methods support both object-based lossless and quasi-lossless coding modes. For the cases where low delay is a primary requirement, a macroblock-based coding mode is proposed which can take advantage of inter-frame coding to improve the coding efficiency. The approach presented here relies on a grid different from that used for the pixels to represent the shape - the hexagonal grid - which simplifies the task of contour coding. Using this grid, an approach based on a differential chain code (DCC) is proposed for the lossless mode while, for the quasi-lossless case, an approach based on the multiple grid chain code (MGCC) principle is proposed. The MGCC combines both contour simplification and contour prediction to reduce the number of bits needed to code the shapes. Results for alpha plane coding of MPEG-4 video test sequences are presented in order to illustrate the performance of the several modes of operation, and a comparison is made with the shape-coding tool chosen by MPEG-4. (C) 2000 Elsevier Science B.V. All rights reserved.","Title: Adaptive Bilateral Filter For Improved In-Loop Filtering In The Emerging High Efficiency Video Coding Standard\nYear: 2012\n\nAbstract: To face the still growing video compression needs, ITU and MPEG have jointly started a standardization project called High Efficiency Video Coding (HEVC) which aims to improve the compression efficiency of the state-of-the-art H. 264/AVC standard for high and ultra high definition video. The HEVC codec still relies on the usual motion compensated, predictive, block based transform coding architecture with block sizes higher than 8x8 being now considered. Furthermore, the codec is also equipped with a Wiener in-loop filter which, together with the H. 264/AVC deblocking filter, further reduces the distortion between the original and decoded frames introduced by lossy coding. While this filter allows indeed reducing the sum of square differences between the original and reconstructed frames, it is not specifically designed to reduce the ringing artifacts resulting from the use of large transform block sizes. In this context, this paper proposes to combine an adaptive bilateral filter together with the HEVC Wiener filter. The proposed combined filter allows an average bitrate reduction of about 7% regarding the HEVC codec without the Wiener filter and a 1.5% reduction regarding the HEVC codec with only the Wiener filter, always for the same quality. Moreover, the combined filter also reduces the ringing artifacts according to an objective metric specifically designed to quantify this type of coding artifact.","Title: Developments and trends on video coding: is there a xVC virus?\nYear: 2008\n\nAbstract: Video coding is a key technology behind the deployment of many devices, and services largely used nowadays around the world. After the first major developments in the 90s, recent years have seen the emergence of new needs, technologies and standards in the video coding domain. This paper intends to review the recent achievements in video coding technology and analyze the rising trends, highlighting problems and research directions.","Title: A Context Pattern Induction Method for Named Entity Extraction.\nYear: 2006\n\nAbstract: We present a novel context pattern induction method for information extraction, specifically named entity extraction. Using this method, we extended several classes of seed entity lists into much larger high-precision lists. Using token membership in these extended lists as additional features, we improved the accuracy of a conditional random field-based named entity tagger. In contrast, features derived from the seed lists decreased extractor accuracy.","Title: Complexity efficient stopping criterion for LDPC based distributed video coding\nYear: 2009\n\nAbstract: In several distributed video coding architectures, a well-known complexity trade-off exists, where the low encoding benefits are paid with a higher decoding complexity. In a feedback channel based DVC architecture, the high decoding complexity is mainly due to the Slepian-Wolf decoding and the repetitive request-decode operation, especially when there is no initial encoder rate estimation or iterative motion refinement is employed. In this paper, an early stopping criterion for the LDPC syndrome belief propagation decoder is proposed that is able to reduce the number of decoding iterations. As a consequence, a significant reduction of the DVC decoder complexity can be observed with negligible losses in RD performance. The experimental results show reductions up to about 4 times in decoding complexity with a maximum of 0.15dB loss at high bitrates while for low and medium bitrates the RD performance loss is negligible.","Title: Distributional similarity models: clustering vs. nearest neighbors\nYear: 1999\n\nAbstract: Distributional similarity is a useful notion in estimating the probabilities of rare joint events. It has been employed both to cluster events according to their distributions, and to directly compute averages of estimates for distributional neighbors of a target event. Here, we examine the tradeoffs between model size and prediction accuracy for cluster-based and nearest neighbors distributional models of unseen events.","Title: Influence of encoder parameters on the decoded video quality for MPEG-4 over W-CDMA mobile networks\nYear: 2000\n\nAbstract: The MPEG-4 standard provides error resilience tools that can significantly increase the decoded video quality when using error prone media to transmit or store the encoded data. However, the use of these tools introduces extra redundancy and overhead in the bitstreams, which means that the decoded video quality can be severely affected if no careful configuration of the relevant parameters is done while taking into account the error characteristics of the channel being used. In this paper, a videotelephony system over a W-CDMA mobile network is used to study the influence of the encoding parameters on the decoded video quality, notably its behavior and optimization.","Title: Flexible text segmentation with structured multilabel classification\nYear: 2005\n\nAbstract: Many language processing tasks can be reduced to breaking the text into segments with prescribed properties. Such tasks include sentence splitting, tokenization, named-entity extraction, and chunking. We present a new model of text segmentation based on ideas from multilabel classification. Using this model, we can naturally represent segmentation problems involving overlapping and non-contiguous segments. We evaluate the model on entity extraction and noun-phrase chunking and show that it is more accurate for overlapping and non-contiguous segments, but it still performs well on simpler data sets for which sequential tagging has been the best method.","Title: Generating summary keywords for emails using topics\nYear: 2008\n\nAbstract: Email summary keywords, used to concisely represent the gist of an email, can help users manage and prioritize large numbers of messages. We develop an unsupervised learning framework for selecting summary keywords from emails using latent representations of the underlying topics in a user's mailbox. This approach selects words that describe each message in the context of existing topics rather than simply selecting keywords based on a single message in isolation. We present and compare four methods for selecting summary keywords based on two well-known models for inferring latent topics: latent semantic analysis and latent Dirichlet allocation. The quality of the summary keywords is assessed by generating summaries for emails from twelve users in the Enron corpus. The summary keywords are then used in place of entire messages in two proxy tasks: automated foldering and recipient prediction. We also evaluate the extent to which summary keywords enhance the information already available in a typical email user interface by repeating the same tasks using email subject lines.","Title: Non-projective dependency parsing using spanning tree algorithms\nYear: 2005\n\nAbstract: We formalize weighted dependency parsing as searching for maximum spanning trees (MSTs) in directed graphs. Using this representation, the parsing algorithm of Eisner (1996) is sufficient for searching over all projective trees in O(n3) time. More surprisingly, the representation is extended naturally to non-projective parsing using Chu-Liu-Edmonds (Chu and Liu, 1965; Edmonds, 1967) MST algorithm, yielding an O(n2) parsing algorithm. We evaluate these methods on the Prague Dependency Treebank using online large-margin learning techniques (Crammer et al., 2003; McDonald et al., 2005) and show that MST parsing increases efficiency and accuracy for languages with non-projective dependencies.","Title: Cloud Based IOPT Petri Net Simulator to Test and Debug Embedded System Controllers.\nYear: 2015\n\nAbstract: IOPT-Tools is a cloud based integrated development environment to the design of embedded system controllers and other digital systems, employing the IOPT Petri net modeling formalism. The tools include a graphical editor, a state-space based model-checking subsystem and automatic code generators to deploy the controllers on the target hardware platforms. This paper presents a new Simulator tool that offers the capability to execute embedded system controllers based on IOPT models in a Web browser. To allow the test and debug of embedded system controllers, the Simulator provides options to manipulate the value of input signals, step by step execution, and continuous execution with programmed step frequency and breakpoint definition. Simulation history is recorded, continuously storing information about the entire system state, to enable playback and history navigation. History data can later be exported in spreadsheet format for analysis with external tools and waveform drawing. The tool can be accessed from http://gres.uninova.pt.","Title: Multimedia Content Adaptation: May One Fit All?\nYear: 2004\n\nAbstract: The growing heterogeneity of networks, terminals and users and the increasing availability and usage of multimedia content have been raising the relevance of content adaptation technologies able to fulfill the needs associated to all usage conditions without multiplying the number of versions available for the same piece of content. This paper discusses the problem of content adaptation considering the major technologies which may have a role in achieving the 'one fits all' content provision paradigm.","Title: Correlation modeling for a distributed scalable video codec based on the HEVC standard.\nYear: 2014\n\nAbstract: The growing heterogeneity of networks, devices and consumption conditions asks for flexible and adaptive video coding solutions. The compression power of the HEVC standard and the benefits of the distributed video coding paradigm allow designing novel scalable coding solutions with improved error robustness and low encoding complexity while still achieving competitive compression efficiency. In this context, this paper proposes a novel scalable video coding scheme using a HEVC Intra compliant base layer and a distributed coding approach in the enhancement layers (EL). This design inherits the HEVC compression efficiency while providing low encoding complexity at the enhancement layers. The temporal correlation is exploited at the decoder to create the EL side information (SI) residue, an estimation of the original residue. The EL encoder sends only the data that cannot be inferred at the decoder, thus exploiting the correlation between the original and SI residues; however, this correlation must be characterized with an accurate correlation model to obtain coding efficiency improvements. Therefore, this paper proposes a correlation modeling solution to be used at both encoder and decoder, without requiring a feedback channel. Experiments results confirm that the proposed scalable coding scheme has lower encoding complexity and provides BD-Rate savings up to 3.43% in comparison with the HEVC Intra scalable extension under development.","Title: Texture refreshment need metric for resilient object-based video coding\nYear: 2002\n\nAbstract: Video encoders may use several techniques to improve error resilience. In particular, for video encoders that rely on predictive (inter) coding to remove temporal redundancy, intra coding refreshment is especially useful to stop error propagation when errors occur in the transmission or storage of the coded streams, which can cause the decoded quality to decay very rapidly. In object-based video coders, intra coding refreshment can be applied to both shape and texture data. A texture refreshment need metric is proposed which can be used by object-based video encoders, notably MPEG-4 video encoders, to determine when the texture of the various video objects in a scene should be refreshed in order to improve the decoded video quality, e.g. for a certain amount of bitrate resources.","Title: Shape refreshment need metric for object-based resilient video coding\nYear: 2002\n\nAbstract: Although there are several techniques that video encoders may use to improve error resilience, it is largely recognized that intra coding refreshment plays a major role. This technique is especially useful for video encoders that rely on predictive (inter) coding to remove temporal redundancy because, in these conditions, the decoded quality can decay very rapidly due to error propagation if errors occur in the transmission or storage of the coded streams. Therefore, in order to avoid error propagation for too long a time, the encoder can use a coding refreshment scheme to refresh the decoding process and stop (spatial and temporal) error propagation. In the context of object-based video coding, the video encoder can apply intra coding refreshment to both the shape and the texture data. A shape refreshment need metric is proposed which can be used by object-based video encoders, notably MPEG-4 video encoders, to determine when the shape of a given video object should be refreshed in order to improve the decoded video quality.","Title: Spatial shape error concealment for object-based image and video coding.\nYear: 2004\n\nAbstract: In this paper, an original spatial shape error-concealment technique, to be used in the context of object-based image and video coding schemes, is proposed. In this technique, it is assumed that the shape of the corrupted object at hand is in the form of a binary alpha plane, in which some of the shape data is missing due to channel errors. From this alpha plane, a contour corresponding to the border of the object can be extracted. However, due to errors, some parts of the contour will be missing and, therefore, the contour will be broken. The proposed technique relies on the interpolation of the missing contours with Be´zier curves, which is done based on the available surrounding contours. After all the missing parts of the contour have been interpolated, the concealed alpha plane can be easily reconstructed from the fully recovered contour and used instead of the erroneous one improving the final subjective impact.","Title: Hierarchical visual description schemes for still images and video sequences\nYear: 1999\n\nAbstract: This paper proposes two description schemes (DSs) to describe the visual information of an audio-visual (AV) document. The first one, is devoted to still images. It describes the image visual appearance and its structure with regions as well as its semantic content in terms of objects. The second DS is devoted to video sequences. It describes the sequence structure as well as its semantic content in terms of events. Features such as motion, camera activity, etc. are included in this DS. Moreover, it involves static visual representations such as key-frames, background mosaics and key-regions. These elements are considered as still images and are described by the first DS.","Title: Improving Turbo Codec Integration in Pixel-Domain Distributed Video Coding\nYear: 2006\n\nAbstract: The field of distributed video coding (DVC) theory has received a lot of attention in recent years and effective encoding techniques have been proposed. In the present work the framework of pixel domain Wyner-Ziv coding of video frames is considered, following the scheme proposed in A. Aaron et al. (2002). Some key frames are supposed to be available at the decoder while other frames are Wyner-Ziv encoded using turbo codes; at the decoder motion compensated interpolation between the key frames is performed in order to construct the side information for the Wyner-Ziv frame decoding. In this paper an improved model for the correlation noise between the side information frame and the original one is proposed. It is shown that modeling the nonstationary nature of the noise leads to substantial gain in the rate-distortion performance. Furthermore, by considering the memory of the noise, we show that some further gain can be obtained by placing an interleaver before the turbo codec so as to spread the correlation noise all over the frame","Title: Objective evaluation of relative segmentation quality\nYear: 2000\n\nAbstract: ABSTRACT When working in image and video segmentation, the major objective is to design an algorithm,producing,the appropriate segmentation,results for the particular goals of the application addressed. Therefore, the assessment of the segmentation quality assumes,a crucial importance,to evaluate the likeliness that the application targets are met. Since,no well-established ,methods ,for ,objective segmentation quality evaluation are currently available, this paper’s major ,goal is to propose ,objective metrics for the evaluation,of ,relative segmentation ,quality for ,both individual objects and the overall segmentation,partition. The paper presents a methodology,for performing,objective evaluation of relative segmentation quality, identifies the relevant,features ,to be ,compared ,against ,those ,of the reference segmentation, and proposes appropriate objective quality,metrics. These ,metrics ,build ,on the ,existing knowledge,on segmentation ,quality evaluation ,and ,also on some,relevant aspects from the video quality evaluation field.","Title: An alternative complexity model for the MPEG-4 video verifier mechanism\nYear: 2001\n\nAbstract: MPEG-4 is the first object-based audiovisual coding standard. To control the minimum decoding complexity resources required at the decoder, the MPEG-4 visual standard defines the so-called video complexity verifier (VCV). This paper proposes an alternative VCV model, based on a set of relative macroblock (MB) complexity weights assigned to the various MB coding types used in MPEG-4 video coding. The new VCV model allows a more efficient use of the available decoding resources by preventing the over-evaluation of the decoding complexity of certain MB types and thus making possible to encode scenes (for the same profile@level decoding resources) which otherwise would be considered too demanding","Title: Spatio-Temporal Scene Level Error Concealment for Shape and Texture Data in Segmented Video Content\nYear: 2006\n\nAbstract: In this paper, a novel shape and texture error concealment technique for segmented object-based video scenes is proposed. This technique is different from existing concealment techniques because it considers not only the corrupted video objects to be concealed, but also the context/scene in which they are inserted. In the proposed technique, concealment is done by using information from the current time instant as well as from the past. The obtained results suggest that the use of this technique significantly improves the subjective visual impact of scenes on the end-user, when compared to independent concealment of video objects.","Title: Encoder Rate Control for Transform Domain Wyner-Ziv Video Coding\nYear: 2007\n\nAbstract: Wyner-Ziv (WZ) video coding - a particular case of distributed video coding (DVC) - is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Many of the practical WZ video coding solutions available in the literature make use of a feedback channel (FC) to perform rate control at the decoder which implies there must be a FC available in the application scenario addressed. The FC-based DVC solutions also have implications in terms of delay and decoder complexity since several iterative decoding operations may be needed to decode the data to the target quality level. In this context, this paper proposes an encoder rate control (ERC) solution for the transform domain WZ coding architecture previously using a FC driven rate control. Although this is the first solution in the literature, promising results are achieved with the proposed ERC solution without significantly increase the encoder complexity.","Title: Adaptive Hash-Based Side Information Exploitation for Efficient Wyner-Ziv Video Coding\nYear: 2007\n\nAbstract: Wyner-Ziv video coding is a lossy source coding paradigm where the video statistics are exploited, partially or totally at the decoder. The side information represents a noisy version of the original frame and is generated at the decoder with time consuming motion estimation and compensation tools. This paper proposes a novel bidirectional hash motion estimation framework which enables the decoder to choose between past and/or future reference frames for frame interpolation. New features include the coding of DCT hash with zero-motion, combination of trajectory-based motion interpolation with hash-based motion estimation and adaptive selection of the DCT bands which are sent to the decoder in order to guide the motion estimation procedure. Gains up to 1.2 dB compared to previous motion interpolation approaches may be reached.","Title: Improved Feedback Compensation Mechanisms for Multiple Video Object Encoding Rate Control\nYear: 2007\n\nAbstract: This paper proposes new buffer and video object distortion feedback compensation mechanisms for efficiently dealing with deviations between the ideal and the actual behavior of video scene encoders when jointly encoding multiple arbitrarily shaped video objects in the context of compliant low-delay object-based MPEG-4 video coding. The proposed solution computes target buffer occupancies for each encoding time instant based on the amount and complexity of the video data to encode, and the bit allocation for each encoding time instant is feedback adjusted according to deviations relatively to this ideal behavior. Additionally, each video object bit allocation is also feedback adjusted based on the relative distortion of the various video objects in the scene. The proposed solution outperforms the non-normative MPEG-4 reference rate control algorithm for a wide range of bit rates and spatio-temporal resolutions, for typical test sequences.","Title: Wyner-Ziv Stereo Video Coding using a Side Information Fusion Approach\nYear: 2007\n\nAbstract: Wyner-Ziv coding, also known as distributed video coding, is currently a very hot research topic in video coding due to the new opportunities it opens. This paper applies the distributed video coding principles to stereo video coding, to propose a practical solution for Wyner-Ziv stereo coding based on mask-based fusion of temporal and spatial side informations. The architecture includes a low-complexity encoder and avoids any communication between the cameras/encoders. While the rate-distortion (RD) performance strongly depends on the motion-based frame interpolation (MBFI) and disparity-based frame estimation (DBFE) solutions, first results show that the proposed approach is promising and there are still issues to address.","Title: Error resilient macroblock rate control for H.264/AVC video coding\nYear: 2008\n\nAbstract: In this paper, an error resilient rate control scheme for the H.264/AVC standard is proposed. This scheme differs from traditional rate control schemes in that macroblock mode decisions are not made only to minimize their rate-distortion cost, but also take into account that the bitstream will have to be transmitted through an error-prone network. Since channel errors will probably occur, error propagation due to predictive coding should be mitigated by adequate Intra coding refreshes. The proposed scheme works by comparing the rate-distortion cost of coding a macroblock in Intra and Inter modes: if the cost of Intra coding is only slightly larger than the cost of Inter coding, the coding mode is changed to Intra, thus reducing error propagation. Additionally, cyclic Intra refresh is also applied to guarantee that all macroblocks are eventually refreshed. The proposed scheme outperforms the H.264/AVC reference software, for typical test sequences, for error-free transmission and several packet loss rates.","Title: Augmented LDPC graph for distributed video coding with multiple side information\nYear: 2011\n\nAbstract: The advances made in channel-capacity codes, such as turbo codes and low-density parity-check (LDPC) codes, have played a major role in the emerging distributed source coding paradigm. LDPC codes can be easily adapted to new source coding strategies due to their natural representation as bipartite graphs and the use of quasi-optimal decoding algorithms, such as belief propagation. This paper tackles a relevant scenario in distributed video coding: lossy source coding when multiple side information (SI) hypotheses are available at the decoder, each one correlated with the source according to different correlation noise channels. Thus, it is proposed to exploit multiple SI hypotheses through an efficient joint decoding technique with multiple LDPC syndrome decoders that exchange information to obtain coding efficiency improvements. At the decoder side, the multiple SI hypotheses are created with motion compensated frame interpolation and fused together in a novel iterative LDPC based Slepian-Wolf decoding algorithm. With the creation of multiple SI hypotheses and the proposed decoding algorithm, bitrate savings up to 8.0% are obtained for similar decoded quality.","Title: A denoising approach for iterative side information creation in distributed video coding\nYear: 2011\n\nAbstract: In distributed video coding, motion estimation is typically performed at the decoder to generate the side information, increasing the decoder complexity while providing low complexity encoding in comparison with predictive video coding. Motion estimation can be performed once to create the side information or several times to refine the side information quality along the decoding process. In this paper, motion estimation is performed at the decoder side to generate multiple side information hypotheses which are adaptively and dynamically combined, whenever additional decoded information is available. The proposed iterative side information creation algorithm is inspired in video denoising filters and requires some statistics of the virtual channel between each side information hypothesis and the original data. With the proposed denoising algorithm for side information creation, a RD performance gain up to 1.2 dB is obtained for the same bitrate.","Title: Video compression: Discussing the next steps\nYear: 2009\n\nAbstract: Video compression has been intensively evolving for more than 20 years. Until recently, around 50% compression gains every 5 years were obtained, resulting in the current set of video coding standards. More recently, after the development of the very successful H.264/AVC standard, compression gains have been short and more difficult to reach than usual. In this context, this talk will discuss the future of video compression considering the emerging industry needs, notably in terms of promising technological novelties, and recent standardization initiatives targeting 3D video and further video compression efficiency.","Title: Fast rate distortion optimization for the emerging HEVC standard\nYear: 2012\n\nAbstract: The under development High Efficiency Video Coding (HEVC) standard employs several powerful coding tools to obtain improved compression efficiency regarding the state-of-the-art H.264/AVC standard. To efficiently exploit the temporal and spatial redundancies, HEVC adopts a very flexible quadtree coding structure, allowing the encoder to use a block partition better matching the image features. The best combination of HEVC block partitioning and coding modes is found by means of a rate distortion optimization process. During this minimization, the encoder tests all the possible coding modes and block partitions and keeps those providing the smallest RD cost. Due to the large number of available modes and partitions, the minimization involves extremely high complexity, which may not be suitable for real-time application scenarios. To reduce the complexity, two novel fast RDO techniques are proposed in this paper: Top Skip and Early Termination. The experimental evaluation reveals that the proposed techniques significantly reduce the encoding time, notably up to 45% regarding the high complexity HEVC reference software codec, with a negligible quality loss never larger than 0.1 dB.","Title: Structural based side information creation with improved matching criteria for Wyner-Ziv video coding\nYear: 2012\n\nAbstract: The Wyner-Ziv video coding (WZVC) efficiency is highly dependent on the quality of the side information (SI) created at the decoder, typically through motion compensated frame interpolation (MCFI) techniques. Since the decoder only has available some reference decoded frames, SI creation turns out to be a difficult problem in WZVC. In most the MCFI techniques available, the matching criterion used for motion estimation only takes into account the (mean of absolute) pixel differences within a block which is limiting for some content types. This paper proposes a structural based SI creation approach with improved matching criteria combining local image features, obtained from the histogram of oriented gradients (HOG), with a boundary continuity criterion and the typical pixel differences criterion. With the structural based SI creation, the motion estimation process becomes more robust, e.g. to illumination changes, thus improving the SI quality (up to 0.4 dB) and reducing the bitrate (up to 6 % in terms of the Bjontegaard metric) regarding a state-of-the-art MCFI solution.","Title: On the extension of classical calculus of variations and optimal control to problems with discontinuous trajectories\nYear: 2012\n\nAbstract: In this article, we present a proper extension of the problems of classical calculus of variations and of optimal control to the case of discontinuous trajectories. An appropriate impulsive control problem is introduced as a result of such extension. Existence theorems are proved under assumptions of the Filippov type.","Title: Decoder side just noticeable distortion model estimation for efficient H.264/AVC based perceptual video coding\nYear: 2010\n\nAbstract: This paper proposes a decoder side estimation for a just noticeable distortion perceptual model integrated in the H.264/AVC codec to improve its RD performance. The proposed estimation avoids having to send the perceptual weights used during the quantization of each frequency coefficient. Experiments with high definition videos show that the novel perceptual video codec is able to reduce the bitrate up to about 34% at the cost of, at most, 1.2% objective multi scale structural similarity quality loss. Moreover, the RD performance with the estimation is comparable to the performance achieved if the original perceptual model is used at the decoder without considering the associated rate.","Title: IOPT-tools — A Web based tool framework for embedded systems controller development using Petri nets\nYear: 2013\n\nAbstract: The IOPT-tools Web based tool framework supports the implementation of embedded systems controllers using web-based graphical tools, starting with a graphical editor to specify controller's behavior through associated Petri-net model, complemented with model-checking and system verification tools used to debug and automatically check controller behavior correctness (helping in the detection of model flaws during the early design stages), leading to the final controller implementation code amenable to be deployed into specific platforms and using automatic code generation tools creating C code for software solutions or VHDL code for hardware descriptions.","Title: An Efficient Encoder Rate Control Solution for Transform Domain Wyner–Ziv Video Coding\nYear: 2011\n\nAbstract: Most Wyner-Ziv (WZ) video coding solutions in the literature use a feedback channel (FC) based decoder rate control (DRC) strategy to adjust the bitrate to correct the side information (SI) errors. More recently, some encoder rate control (ERC) strategies have been proposed to address application scenarios where a FC is not available. The ERC based WZ video coding RD performance depends not only on the (encoder) parity rate estimator (PRE) accuracy but also on the decoder “intelligence” in dealing with the residual errors due to parity rate underestimation. In this context, the main objective of this paper is to propose a more efficient and powerful ERC solution for transform domain WZ (TDWZ) video coding by simultaneously tackling the two issues aforementioned with the following technical novelty: 1) integration in an ERC context of Gray mapping for the quantized DCT coefficients to enhance the correlation between WZ and SI data; 2) more accurate PRE to better estimate the needed parity rate to avoid undesired parity rate underestimations and overestimations; 3) novel soft reconstruction function to reduce the impact of the residual bitplane errors in the decoded WZ frame quality; and 4) weighted overlapped block motion compensation technique to refine the SI used in an iterative WZ decoding framework with the correlation noise model parameters dynamically updated. Experimental results show a considerable RD performance improvement with a reduction of up to about 2 dB of the gap between the ERC and DRC based approaches in TDWZ video coding solutions, thus making this ERC based WZ codec the most efficient available and competitive regarding DRC based WZ video coding solutions.","Title: Perceptually driven coefficients pruning and quantization for the H.264/A VC standard\nYear: 2011\n\nAbstract: The increasing production and delivery of video contents in higher spatio-temporal resolutions is currently demanding for higher compression efficiency, notably beyond the state-of-art H.264/AVC video coding standard. Since the human viewers are always the last quality judge, the compression efficiency can be improved by exploiting the properties of the human visual system. This paper studies the integration of two perceptual coding tools, namely coefficient pruning and perceptual quantization step adjustment, in a H.264/AVC compliant video codec architecture. The obtained perceptually driven video codec allows reducing the coding rate up to 35% for the same visual quality in comparison with the reference H.264/AVC standard.","Title: Integrating a spatial just noticeable distortion model in the under development HEVC codec\nYear: 2011\n\nAbstract: Although great achievements have been obtained in the past, recent developments towards ultra high definition video have been asking for further compression efficiency gains regarding the H.264/AVC state-of-the-art. As an answer to these needs, ITU-T and MPEG started a new standardization project called High Efficiency Video Coding. This paper extends and integrates a perceptual visual model in the High Efficiency Video Coding experimental codec to improve its RD performance. The designed extensions are related to the new Integer Discrete Cosine Transform block sizes as well as the new Mode Dependent Directional Transform. Moreover, an estimation mechanism for the perceptual model at the decoder side is also integrated to avoid the rate burden of sending to the decoder the model parameters. The RD performance is assessed using a methodology taking into account the variability of subjective scores which is reflected into a nonlinear sensitivity of the subjective quality metric. The RD performance obtained for the perceptually driven codec shows a bitrate reduction of up to 43% regarding the non-perceptual video codec.","Title: Feedback channel in pixel domain Wyner-Ziv video coding: Myths and realities\nYear: 2006\n\nAbstract: Wyner-Ziv (WZ) video coding - a particular case of distributed video coding (DVC) - is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Recently, practical WZ video coding solutions were proposed with promising results. Many of the solutions avail- able in the literature make use of a feedback channel (FC) to per- form rate control at the decoder. In this context, this paper intends to analyse the impact of this feedback channel, notably through a number of metrics such as the frequency the feedback channel is used as well as its associated rate. It is also presented a study on the evolution of the decoded frames quality as more parity bits are requested via feedback channel. Those measures are important since they allow characterizing the usage of the feedback channel, and have never been presented in the literature.","Title: Automatic and adaptive network-aware macroblock intra refresh for error-resilient H.264/AVC video coding\nYear: 2009\n\nAbstract: In this paper, an automatic and adaptive network-aware macroblock Intra coding refresh method is proposed. It adaptively selects the amount of gracefully forced Intra macroblocks and the amount of cyclic Intra refresh (CIR) macroblocks based on the actual network error conditions, in terms of packet loss rate, and the target encoding bit rate. With the proposed method, the error robustness of H.264/AVC bitstreams can be significantly increased by efficiently taking into account the actual rate-distortion impact of Intra coding macroblock mode decisions, while simultaneously guaranteeing that errors do not propagate endlessly by selecting an adequate amount of CIR macroblocks per frame according to the network packet loss rate and the encoding target bit rate.","Title: Multi-technology RF fingerprinting with leaky-feeder in underground tunnels\nYear: 2012\n\nAbstract: Techniques using RSS fingerprinting for localization have been studied over a number of different technologies in many different scenarios. In the case of underground tunnels localization can be quite challenging, yet it is extremely important for safety reasons. In the specific case of the CERN tunnels, accurate and automatized localization methods would additionally allow the workflow of some activities to become substantially faster. In a radiation area this would also have the added benefit of reducing the exposure time of personnel conducting so called radiation surveys which have to be carried out before access can be granted. In this paper Fingerprinting techniques for GSM and Wireless LAN are studied and enhanced to take advantage of both network technologies simultaneously as well as the channels RSS differential and an observed effect in the radiated power in the leaky-feeder cables. Besides the higher accuracy achieved for a single technology, this methodology looks promising for scenarios where several types of wireless networks are available or expected to be installed at a later stage.","Title: Improving predictive video coding performance with decoder side information\nYear: 2012\n\nAbstract: Although major achievements have been reached in terms of video compression efficiency, additional gains are still needed to satisfy current and emerging applications needs. This trend justifies the continuous efforts to go beyond the compression capabilities of the state-of-the-art H.264/AVC standard. This paper proposes to further bridge two video coding approaches, the popular predictive and the emerging distributed coding paradigms, by proposing a novel bidirectional (B) coding process to be integrated in the H.264/AVC codec, inspired by the side information creation module, central in distributed video coding. The novel B-slice coding process builds on a new reference frame, the side information frame, which is both created at the encoder and decoder, as the SI creation method does not need the original to be available. The experimental results for the novel coding solution show average bitrate savings of 5.89% both for the low and high bitrate regions.","Title: Using MPEG standards for multimedia customization\nYear: 2004\n\nAbstract: The multimedia content delivery chain poses today many challenges. The increasing terminal diversity, network heterogeneity and the pressure to satisfy the user preferences are raising the need for content to be customized in order to provide the user the best possible experience. This paper addresses the problem of multimedia customization by (1) presenting the MPEG-7 multimedia content description standard and the MPEG-21 multimedia framework; (2) classifying multimedia customization processing algorithms; (3) discussing multimedia customization systems; and (4) presenting some customization experiments.","Title: Optimal Layered Representation for Adaptive Interactive Multiview Video Streaming\nYear: 2015\n\nAbstract: We consider an interactive multiview video streaming (IMVS) system where clients select their preferred viewpoint in a given navigation window. To provide high quality IMVS, many high quality views should be transmitted to the clients. However, this is not always possible due to the limited and heterogeneous capabilities of the clients. In this paper, we propose a novel adaptive IMVS solution based on a layered multiview representation where camera views are organized into layered subsets to match the different clients constraints. We formulate an optimization problem for the joint selection of the views subsets and their encoding rates. Then, we propose an optimal and a reduced computational complexity greedy algorithms, both based on dynamic-programming. Simulation results show the good performance of our novel algorithms compared to a baseline algorithm, proving that an effective IMVS adaptive solution should consider the scene content and the client capabilities and their preferences in navigation.","Title: Computationally efficient modelling of tidal rivers using conceptual reservoir-type models\nYear: 2016\n\nAbstract: Conceptual reservoir-type models of river systems, that mimic the results of detailed hydrodynamic models, provide a powerful tool for numerous river management applications. Thanks to their computationally efficient model structure they are very well suited for applications that require long term simulations or a large number of model iterations. However, one well-known problem is that conceptual models have difficulties to account for backwater effects. For this reason, their application to tidally influenced river reaches so far was almost non-existent. This paper introduces an extension of an existing grey-box reservoir modelling technique to incorporate tidally influenced river reaches. The methodology is demonstrated for the downstream part of the rivers Zenne and Rupel in Belgium. Results show a minor loss of accuracy when the detailed model is replaced by the surrogate conceptual model. Also, the tidal effects are well represented. A surrogate modelling approach for tidally influenced river reaches is developed.The approach is modular, flexible and compatible with other reservoir-type models.A discrete and explicit calculation scheme that allows for very short calculation times is used.A case study of the rivers Zenne and Rupel in Belgium was used to demonstrate the accuracy of the modelling approach.","Title: Combining Data-Flows and Petri Nets for Cyber-Physical Systems Specification.\nYear: 2016\n\nAbstract: This paper proposes a new modeling formalism for the specification of cyber-physical systems, combining the functionality offered by Petri nets and synchronous data flows. Petri nets have been traditionally used to model the behavior of reactive systems, whose state evolves depending on the interaction with external events. On the opposite, data-flow formalisms have been used predominantly to describe data-driven systems that produce output data through mathematical transformations applied to input signals. The proposed formalism covers both kinds of problems, offering support for the design of mixed systems containing linear control and signal processing operations along with event driven elements. Model composition using multiple components communicating through input and output signals and events, enable the implementation of distributed cyber-physical systems. The new formalism and the respective execution semantics are presented, with special attention to the bidirectional interaction between Petri net elements and data-flow nodes.","Title: The VISNET II DVC codec: Architecture, tools and performance\nYear: 2010\n\nAbstract: This paper introduces the VISNET II DVC codec. This codec achieves very high RD performance thanks to the efficient combination of many state-of-the-art coding tools into a fully practical video codec. Experimental results show that the proposed DVC codec consistently outperforms H.264/AVC Intra. For sequences with coherent motion, it even surpasses H.264/AVC zero-motion. Finally, it is also always better than the DISCOVER DVC codec. Therefore, it is expected that the proposed high performing DVC codec will be used by other researchers in the field as a reference to benchmark their results.","Title: Report on the evaluation of current and future image compression technologies\nYear: 2015\n\nAbstract: This document reports the conclusions, comments and recommendations resulting from the final panel discussion which happened at the Session on Evaluation of Current and Future Image Compression Technologies held at the Picture Coding Symposium, Cairns, Australia, in June 2015.","Title: Improving enhancement layer merge mode for HEVC scalable extension\nYear: 2015\n\nAbstract: In the HEVC scalable extension (SHVC), the merge mode prediction plays an important role due to its high selection probability and its low associated bitrate. In the SHVC enhancement layer (EL) merge mode prediction, the motion information is selected from the merge candidates, in this case the spatial, temporal, and inter-layer candidates. Therefore, the merge mode prediction is usually inefficient when the motion vector field (MVF) correlation between the merge candidates and the current EL block is low, especially in video sequences containing high motion activity. To address this problem, this paper proposes an improved EL merge mode prediction solution that adaptively refines the motion vector candidates by using both base layer (BL) and EL decoded information and after linearly combines the motion compensated samples with the BL reconstructed samples to achieve a better merge mode prediction quality. Experiments conducted for a rich set of test conditions have shown that significant compression efficiency gains can be achieved with the proposed improved scalable coding solution, notably up to 4.57% in BD-rate savings regarding the standard SHVC quality scalable codec.","Title: Descriptor-based adaptive tracking-by-detection for visual sensor networks\nYear: 2015\n\nAbstract: Local descriptors represent a powerful tool, which is exploited in several applications such as visual search, object recognition and visual tracking. Real-valued visual descriptors such as SIFT and SURF achieve state-of-the-art accuracy performance for a large set of visual analysis tasks. However, such algorithms are demanding in terms of computational capabilities and bandwidth, being unsuitable for scenarios where resources are constrained. In this context, binary descriptors provide an efficient alternative to real-valued descriptors, due to their low computational complexity, limited memory footprint and fast matching algorithms. In this paper, binary descriptors are used to perform visual tracking of an object along time. The proposed visual tracker performs descriptor matching between consecutive frames, applies filtering techniques to remove undesirable outliers and employs a suitable model to characterize the object appearance. In addition, techniques to code and transmit these description streams are employed, thus reducing the amount of data necessary to transmit to perform accurate object tracking. The efficiency of the proposed visual tracker is evaluated in terms of rate-accuracy, i.e. using the bitrate associated to the compressed binary descriptors and a quantitative metric to assess the accuracy of the visual tracker.","Title: Remote operation of embedded controllers designed using IOPT Petri-nets\nYear: 2015\n\nAbstract: This paper presents a new communication architecture to enable the remote control, monitoring and debug of embedded-system controllers designed using IOPT Petri nets. IOPT Petri nets and the related tools (http://gres.uninova.pt) have been used as a rapid prototyping and development framework, including model-checking, simulation and automatic code generation tools. The new architecture adds remote operation capabilities to the controllers produced by the automatic code generators, enabling quasi-real-time remote debugging and monitoring using the IOPT simulator tool. Furthermore, it enables the creation of graphical user interfaces for remote operation and the development of distributed systems where a Petri net model running on a central system supervises the actions of multiple remote subsystems.","Title: Epipolar plane image based rendering for 3D video coding\nYear: 2015\n\nAbstract: In current 3D video coding solutions, such as the 3D-HEVC standard, depth data is instrumental to have a continuum of views synthesized at the decoder based on a limited set of coded views. In order view synthesis may be performed at the decoder, depth data is currently directly acquired or estimated at the encoder based on very few neighboring views and transmitted to the decoder after appropriate compression. At the decoder, further views then those decoded are synthesized using again very few neighboring decoded views, thus using a local synthesis approach. A promising alternative synthesis approach may consider not a few but rather all the views available at the decoder, thus offering a scene global approach to synthesis. One way to implement this approach involves cutting the views cube along the viewpoint direction, creating the so-called epipolar plane images (EPI) which provide a rather compact representation of the scene. In this context, this paper proposes an EPI based view rendering framework for 3D video coding solution and identifies the major benefits of such framework, notably in comparison with the traditional local synthesis approach.","Title: Collective Entity Resolution With Multi-Focal Attention\nYear: 2016\n\nAbstract: Entity resolution is the task of linking each mention of an entity in text to the corresponding record in a knowledge base (KB). Coherence models for entity resolution encourage all referring expressions in a document to resolve to entities that are related in the KB. We explore attention-like mechanisms for coherence, where the evidence for each candidate is based on a small set of strong relations, rather than relations to all other entities in the document. The rationale is that document-wide support may simply not exist for non-salient entities, or entities not densely connected in the KB. Our proposed system outperforms state-of-the-art systems on the CoNLL 2003, TAC KBP 2010, 2011 and 2012 tasks.","Title: Multi-view distributed source coding of binary features for visual sensor networks.\nYear: 2016\n\nAbstract: Visual analysis algorithms have been mostly developed for a centralized scenario where all visual data is acquired and processed at a central location. However, in visual sensor networks (VSN), several constraints in computational power, energy and bandwidth require a radically different approach, notably a paradigm shift from centralized to distributed visual processing. In the new paradigm, visual data is acquired and features are extracted at the sensing nodes locations to be after transmitted to enable further analysis at some central location. In such scenario, one of the key challenges is to design suitable feature coding schemes that are able to exploit the correlation among the features corresponding to (partially) overlapped views of the same visual scene. To achieve efficient coding, it is proposed to employ the distributed source coding paradigm as it does not require any communication between the sensing nodes (rather expensive in VSN) and it is parsimonious in terms of computational resources. Experimental results show that significant accuracy and compression gains (up to 37.36%) can be achieved when coding features extracted from multiple views.","Title: The IOPT-Flow Modeling Framework Applied to Power Electronics Controllers.\nYear: 2017\n\nAbstract: The input-output place-transition (IOPT)-flow modeling framework was created to support the design of mixed embedded system controllers containing both reactive and data-driven parts, combining Petri net and dataflow elements. The reactive parts, whose evolution depends on external events, are modeled using Petri nets. Data manipulation operations that process input signals and events are expresse...","Title: Technical program chairs' overview\nYear: 2016\n\nAbstract: Presents the introductory welcome message from the conference proceedings. May include the conference officers' congratulations to all involved with the conference event and publication of the proceedings record.","Title: The IST-EURECOM Light Field Face Database\nYear: 2017\n\nAbstract: Light field cameras are emerging as powerful devices to capture rich scene representations that provide unique advantages for analysis and representation purposes. Some recent works have shown the power and usefulness of the richer information carried out by light field imaging, notably for face recognition. However, it is still difficult to fully assess how face recognition technology can benefit from these novel imaging sensors, notably due to the lack of appropriate test material. To support face recognition research exploiting light field images, the IST-EURECOM Light Field Face Database (IST-EURECOM LFFD) is presented in this paper. The purpose is to report the public availability of a light field face database which should be instrumental for designing, testing and validating light field imaging based recognition systems. The proposed face database includes data from 100 subjects, captured by a Lytro ILLUM camera in two 1-6 months separated sessions, with 20 samples per each person per session. To simulate multiple scenarios, the images are captured with several facial variations, covering a range of emotions, actions, poses, illuminations, and occlusions. The database includes the raw light field images, 2D rendered images and associated depth maps, along with a rich set of metadata. The IST-EURECOM LFFD is expected to become a valuable addition to existing face database repositories.","Title: Adaptive Scalable Video Coding: An HEVC-Based Framework Combining the Predictive and Distributed Paradigms.\nYear: 2017\n\nAbstract: The emerging scalable High Efficiency Video Coding (SHVC) video coding standard provides an efficient solution for transmission of video over heterogeneous and time dynamic networks, terminals, and usage environments. The encoding complexity and the error sensitivity associated with the efficient HEVC coding tools adopted in SHVC make this scalable codec less attractive to some emerging applicatio...","Title: Subjective and objective quality evaluation of 3D point cloud denoising algorithms\nYear: 2017\n\nAbstract: The increasing availability of point cloud data in recent years is demanding for high performance denoising methods and compression schemes. When point cloud data is directly obtained from depth sensors or extracted from images acquired from different viewpoints, imprecisions on the depth acquisition or in the 3D reconstruction techniques result in noisy point clouds which may include a significant number of outliers. Moreover, the quality assessment of point clouds is a challenging problem since this 3D representation format is unstructured and it is typically not directly visualized. In this paper, selected objective quality metrics are evaluated regarding their correlation with human quality assessment and thus human perception. As far as the authors know, this is the first paper performing the subjective assessment of point cloud denoising algorithms and the evaluation of most used point cloud objective quality metrics. Experimental results show that graph-based denoising algorithms can improve significantly the point cloud quality data and that objective metrics that model the underlying point cloud surface can correlate better with human perception.","Title: Image coding based on patch-driven inpainting.\nYear: 2017\n\nAbstract: Recent advances in capturing and display technologies, as well as the proliferation of platforms to share images on the Internet, will further increase the bandwidth and storage space required by image coding based applications. To reduce the image coding rate, some techniques taking into account the properties of the human visual system can be used. In this context, this paper proposes an inpainting based image codec which is able to improve the image compression efficiency. The proposed codec builds on top of the JPEG image coding standard and its rate-distortion performance is assessed using a novel methodology, particularly suitable for perceptual image codecs as the one proposed in this paper. According to this methodology, the proposed image codec allows a bitrate reduction of up to about 20% regarding the JPEG standard, at the same perceptual quality.","Title: A geometric space-view redundancy descriptor for light fields: Predicting the compression potential of the JPEG Pleno light field datasets\nYear: 2017\n\nAbstract: The representation of data in terms of its statistical properties is valuable in many applications. This work uses statistics obtained from 4D scene geometry to characterize, in terms of redundancy, the content produced by lenslet-based light field cameras and by high-density arrays of cameras for the JPEG Pleno Call for Proposals on Light Field Coding. This paper proposes a novel so-called geometric space-view redundancy (GSVR) descriptor, which is able to characterize the amount of redundancy in light fields thus bringing information about the trade-offs involved in effectively exploring redundancy for efficient coding. The redundancy is here measured by the probability, for each block size and range of views, that the image of a given 3D point belongs to the block in all views. For a given probability, the GSVR descriptor models the spaceview correlation, i.e. the correlation between the intra-view block dimensions and the number of views. Therefore, it is a descriptor that has application on dataset selection and encoder control and optimization. The JPEG Pleno datasets are analyzed in terms of the GSVR descriptor in all views.","Title: Subjective and objective quality evaluation of compressed point clouds\nYear: 2017\n\nAbstract: The increasing availability of point cloud data in recent years is demanding high performance compression solutions. Naturally, methods to perform objective quality assessment of compressed point clouds are also very much needed, namely metrics to measure the geometry distortion of point clouds when positioning errors are present. This is a rather challenging problem since this 3D representation format is unstructured and it is typically not directly visualized. In this context, the objective of this paper is to perform subjective and objective quality assessment of point clouds degraded by compression artifacts and to evaluate the correlation of the most popular objective quality metrics with human perception. In this work, subjective experiments conducted at Instituto Superior Técnico (IST) are described with point clouds compressed with two different but yet promising solutions, one based on the octree representation of the 3D space and another based on the rather popular graph transform. As far as the authors know, this is the first study of this type made available and should have a key role on the future development and evaluation of point cloud coding solutions.\n<sup xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">1</sup>","Title: Improving point cloud to surface reconstruction with generalized Tikhonov regularization\nYear: 2017\n\nAbstract: Point cloud rendering has a vital role in the user Quality of Experience for applications adopting point cloud based representations. While this is not a new area, it has recently become more relevant with the recent interest on point cloud coding by major standardization groups, notably JPEG and MPEG. The screened Poisson surface reconstruction is a state-of-the-art technique for generating a watertight surface mesh from the point cloud samples. While its screening component allows the surface to better fit the cloud points, this fitting may lead to undesired artifacts in the surface, notably when the point cloud is noisy. This paper proposes to improve this reconstruction method by making it more robust to noise by adopting a generalized Tikhonov regularization term. The proposed regularization approach smooths regions that should be flat while keeping the important details in the edges, thus creating more pleasant surface reconstructions.","Title: Saliency-driven omnidirectional imaging adaptive coding: Modeling and assessment\nYear: 2017\n\nAbstract: Omnidirectional imaging, also known as 360° and spherical imaging, records all 360° of a scene from a specific spatial position, thus offering the user the capability to enjoy three rotational degrees of freedom (3-DoF). To offer a good quality of experience, omnidirectional imaging requires very high bitrates as high spatial resolution are a must and, ideally, also high frame rates. Due to the lack of video coding solutions specifically designed for omnidirectional imaging, this type of content is typically coded with the available image and video coding standards, such as JPEG, H.264/AVC and HEVC, after applying a 2D rectangular projection. In this context, this paper proposes an omnidirectional imaging coding solution allowing to reach improved coding performance by using an adaptive coding solution where the most visually salient image/video regions are coded with higher quality in a process appropriately controlled by the quantization parameter. To determine the saliency of the various omnidirectional imaging regions, a machine-learning based saliency detection model is proposed. The proposed coding solution achieves compression gains as measured by a novel objective quality metric also driven by saliency. This novel objective quality metric is validated by formal subjective testing where very high correlations with the subjective tests scores are achieved.","Title: Holographic Data Coding: Benchmarking and Extending HEVC With Adapted Transforms.\nYear: 2018\n\nAbstract: Holography is an emerging technology to represent and display visual information with high expectations in terms of user experience. A hologram is a reproduction of a light field represented through the interference pattern between two wavefields the reference and the object wavefields. Whatever their creation process holograms may have a digital representation using some appropriate format. Moreo...","Title: Face spoofing detection using a light field imaging framework.\nYear: 2018\n\nAbstract: Face recognition systems are becoming ubiquitous, but they are vulnerable to spoofing attacks. The recently available light field cameras can be used for spoofing attack detection. In this study, the IST Lenslet Light Field Face Spoofing Database (IST LLFFSD) is proposed, consisting of 100 genuine images, from 50 subjects, captured with a Lytro ILLUM lenslet light field camera, and a set of 600 fa...","Title: Light Field Local Binary Patterns Description For Face Recognition\nYear: 2017\n\nAbstract: Light field cameras are emerging as powerful sensor devices to capture the full spatio-angular visual information in a viewing range. As more information should allow better analysis performance, this paper proposes a simple, yet effective descriptor, named Light Field Local Binary Patterns (MAP), able to exploit the richer information available in light field images for face recognition. The LFLBP descriptor combines two main components, the spatial, local LBP and the angular LBP, to capture not only the usual spatial information but also the light field angular information associated to the set of sub-aperture images, corresponding to different viewpoints. Experiments were conducted with the novel IST-EURECOM light field face database. When compared with competing methods, the proposed descriptor has shown superior face recognition performance under varied and challenging acquisition conditions. Moreover, the proposed light field angular LBP descriptor can be flexibly combined with any available spatial descriptor to derive combined descriptors for enhanced light field based face recognition performance.","Title: Light Field-Based Face Presentation Attack Detection: Reviewing, Benchmarking and One Step Further.\nYear: 2018\n\nAbstract: Vulnerability of face recognition systems to presentation attacks has attracted increasing attention from the biometrics and forensics communities. Moreover, the recent availability of light field cameras is opening new possibilities for designing improved face presentation attack detection solutions. In this context, this paper provides the first review and benchmarking study in the literature on...","Title: Ear recognition in a light field imaging framework: a new perspective.\nYear: 2018\n\nAbstract: Ear recognition is an emerging research area in image-based biometrics. The commercial availability of lenslet light field cameras able to capture full spatio-angular information has brought momentum to biometric and forensic research exploiting this new type of imaging sensors. This study is the first to consider the usage of light field cameras for ear recognition, proposing both an appropriate ...","Title: A Study On The 4d Sparsity Of Jpeg Pleno Light Fields Using The Discrete Cosine Transform\nYear: 2018\n\nAbstract: In this work we study the 4D sparsity of light fields using as main tool the 4D-Discrete Cosine Transform. We analyze the two JPEG Pleno light field datasets, namely the lenslet-based and the High-Density Camera Array (HDCA) datasets. The results suggest that the lenslets datasets exhibit a high 4D redundancy, with a larger inter-view sparsity than the intra-view one. For the HDCA datasets, there is also 4D redundancy worthy to be exploited, yet in a smaller degree. Unlike the lenslets case, the intra-view redundancy is much larger than the inter-view one. The results and conclusions of this first study for light field imaging may have a strong impact on the current and future design of efficient codecs for this type of emerging data, notably in the context of the JPEG Pleno standard.","Title: Rate-Distortion Driven Adaptive Partitioning For Octree-Based Point Cloud Geometry Coding\nYear: 2018\n\nAbstract: Point clouds are widely recognized as a promising 3D visual representation model for future 3D applications, e.g. Augmented/Virtual Reality and autonomous mobile navigation. To enable immersive and high quality experiences, a large amount of data needs to be transmitted, and thus, efficient compression techniques are a key factor for its success. Nowadays, many point cloud coding techniques rely on layered octree data structures able to provide multiple benefits, notably level of detail scalability. However, the octree creation process still lacks flexibility compared to the optimal partitioning methods popular in 2D encoders, which are mainly driven by rate-distortion trade-offs. The goal of this paper is to propose a novel octree creation mechanism which is able to exploit the intrinsic point cloud resolution by iteratively partitioning the octree voxels by means of split decisions based on a Rate-Distortion Optimization process. In addition, the arithmetic coding step is adapted to the density at each octree depth. This novel approach allows reaching a significant bitrate reduction, notably 5% in average, and up to 9.8%, over the adopted coding anchor using state-of-the-art octree based coding.","Title: A JSON/HTTP communication protocol to support the development of distributed cyber-physical systems\nYear: 2018\n\nAbstract: Cyber physical systems are often built using networks of components containing physical and computational resources, enabling the design of distributed applications that collect data from remote sensors and manipulate remote actuators, located on local networks or on far away locations. The communication protocol presented in this paper was designed to support the communication between components of distributed applications. In addition, it includes remote debug and monitoring capabilities, to support the detection and resolution of errors and design mistakes on nodes running on remote locations. Employing the JSON/HTTP standards, the proposed protocol is Web browser friendly, suitable for the creation of Web based applications and user interfaces, but it may be employed on most programming environments that offer libraries to support those standards. As it is based on HTTP, it can easily traverse most firewall configurations and used through proxies. Development of the proposed protocol started on the IOPTTools framework, but the current version was implemented as part of the IOPT-Flow framework, aiming the development of distributed CPS applications based on graphical formalism combining Petri nets and dataflows. Both tool frameworks are available at http://gres.uninova.pt.","Title: LIGHT FIELD BASED FACE RECOGNITION VIA A FUSED DEEP REPRESENTATION\nYear: 2018\n\nAbstract: The emergence of light field cameras opens new frontiers in terms of biometric recognition. This paper proposes the first deep CNN solution for light field based face recognition, exploiting the richer information available in a lenslet light field image. Additionally, for the first time, the exploitation of disparity maps together with 2D-RGB images and depth maps has been considered in the context of a fusion scheme to further improve the face recognition performance. The proposed solution uses the 2D-RGB central sub-aperture view as well as the disparity and depth maps extracted from the full set of sub-aperture images associated to a lenslet light field. After, feature extraction is performed using a VGG-Face deep descriptor for texture and independently fine-tuned models for disparity and depth maps. Finally, the extracted features are concatenated to be fed into an SVM classifier. A comprehensive set of experiments has been conducted with the IST-EURECOM light field face database, showing the superior performance of the fused deep representation for varied and challenging recognition tasks.","Title: Lenslet Light Field Imaging Scalable Coding\nYear: 2018\n\nAbstract: Light fields have emerged as one of the most promising 3D representation formats, enabling a richer and more immersive representation of a visual scene. The lenslet light field acquisition approach consists in placing an array of micro-lenses between the camera main lens and the photosensor to allow capturing both the intensity and the direction of the light rays. This type of representation format offers new interaction possibilities with the visual content, notably a posteriori refocusing and visualization of different perspectives of the visual scene. However, this representation model is associated to very large amounts of data, thus requiring efficient coding solutions in order applications involving storage and transmission may be deployed. This paper proposes a novel lenslet light field imaging scalable coding solution adopting a wavelet-based approach, able to offer view, quality and spatial scalabilities, to meet the characteristics of multiple types of displays, transmission channels and user needs. The performance results show that the proposed coding solution performs better than alternative scalable coding solutions, notably JPEG 2000.","Title: Lenslet Light Field Panorama Creation - A Sub-Aperture Image Stitching Approach.\nYear: 2018\n\nAbstract: Typically, a single light field camera only captures a limited portion of the visual scene and the rendered views offer low spatial resolution since the full sensor resolution also needs to capture the light arriving to the sensor from multiple directions. However, many applications require a large field of view and higher spatial resolution, which cannot be offered by a single lenslet light field image. In this paper, a lenslet light field panorama creation solution is proposed based on the stitching of the sub-aperture images associated to several lenslet light fields. The proposed approach consists in capturing multiple light fields with a single lenslet camera, which is rotated to capture different scene angles; corresponding sub-aperture images associated with the multiple light field images are then stitched while avoiding misalignments. The created lenslet light field panorama should preserve the directional light information, thus allowing to change a posteriori the perspective and the objects in focus on a panorama basis.","Title: Ear Presentation Attack Detection: Benchmarking Study with First Lenslet Light Field Database\nYear: 2018\n\nAbstract: Ear recognition has received broad attention from the biometric community and its emerging usage in multiple applications is raising new security concerns, with robustness against presentation attacks being a very active field of research. This paper addresses for the first time the ear presentation attack detection problem by developing an exhaustive benchmarking study on the performance of state-of-the-art light field and non-light field based ear presentation attack detection solutions. In this context, this paper also proposes an appropriate ear artefact database captured with a Lytro ILLUM lenslet light field camera, including both 2D and light field contents, using several types of presentation attack instruments, including laptop, tablet and two different mobile phones. Results show very promising performance for two recent light field based presentation attack detection solutions originally proposed for face presentation attack detection.","Title: Graph-Based Static 3D Point Clouds Geometry Coding.\nYear: 2019\n\nAbstract: Recently, 3D visual representation models such as light fields and point clouds are becoming popular due to their capability to represent the real world in a more complete and immersive way, paving the road for new and more advanced visual experiences. The point cloud representation model is able to efficiently represent the surface of objects/scenes by means of a set of 3D points and associated a...","Title: Face Recognition: A Novel Multi-Level Taxonomy based Survey.\nYear: 2019\n\nAbstract: In a world where security issues have been gaining growing importance, face recognition systems have attracted increasing attention in multiple application areas, ranging from forensics and surveillance to commerce and entertainment. To help to understand the landscape and abstraction levels relevant for face recognition systems, face recognition taxonomies allow a deeper dissection and comparison of the existing solutions. This study proposes a new, more encompassing and richer multi-level face recognition taxonomy, facilitating the organisation and categorisation of available and emerging face recognition solutions; this taxonomy may also guide researchers in the development of more efficient face recognition solutions. The proposed multi-level taxonomy considers levels related to the face structure, feature support, and feature extraction approach. Following the proposed taxonomy, a comprehensive survey of representative face recognition solutions is presented. This study concludes with a discussion on current algorithmic and application related challenges, which may define future research directions for face recognition.","Title: Embedding heterogeneous data using statistical models\nYear: 2006\n\nAbstract: Embedding algorithms are a method for revealing low dimensional structure in complex data. Most embedding algorithms are designed to handle objects of a single type for which pairwise distances are specified. Here we describe a method for embedding objects of different types (such as authors and terms) into a single common Euclidean space based on their co-occurrence statistics. The joint distributions of the heterogenous objects are modeled as exponentials of squared Euclidean distances in a low-dimensional embedding space. This construction links the problem to convex optimization over positive semidefinite matrices. We quantify the performance of our method on two text datasets, and show that it consistently and significantly outperforms standard methods of statistical correspondence modeling, such as multidimensional scaling and correspondence analysis.","Title: Distribution rules with numeric attributes of interest\nYear: 2006\n\nAbstract: In this paper we introduce distribution rules, a kind of association rules with a distribution on the consequent. Distribution rules are related to quantitative association rules but can be seen as a more fundamental concept, useful for learning distributions. We formalize the main concepts and indicate applications to tasks such as frequent pattern discovery, sub group discovery and forecasting. An efficient algorithm for the generation of distribution rules is described. We also provide interest measures, visualization techniques and evaluation.","Title: Learning Bounds for Domain Adaptation\nYear: 2007\n\nAbstract: Empirical risk minimization offers well-known learning guarantees when training and test data come from the same domain. In the real world, though, we often wish to adapt a classifier from a source domain with a large amount of training data to different target domain with very little training data. In this work we give uniform convergence bounds for algorithms that minimize a convex combination of source and target empirical risk. The bounds explicitly model the inherent trade-off between training on a large but inaccurate source data set and a small but accurate target training set. Our theory also gives results when we have multiple source domains, each of which may have a different number of instances, and we exhibit cases in which minimizing a non-uniform combination of source risks can achieve much lower target error than standard empirical risk minimization.","Title: A Double-Deep Spatio-Angular Learning Framework for Light Field based Face Recognition.\nYear: 2018\n\nAbstract: Face recognition has attracted increasing attention due to its wide range of applications but it is still challenging when facing large variations in the biometric data characteristics. Lenslet light field cameras have recently come into prominence to capture rich spatio-angular information, thus offering new possibilities for designing advanced biometric recognition systems. This paper proposes a double-deep spatio-angular learning framework for light field based face recognition, which is able to learn convolutional representations and angular dynamics from a light field image; this is a novel recognition framework that has never been proposed before for either face recognition or any other visual recognition task. The proposed double-deep learning framework includes a long short-term memory (LSTM) recurrent network whose inputs are VGG-Face descriptions, computed using a VGG-Very-Deep-16 convolutional neural network (CNN) for different face viewpoints rendered from the full light field image, which are organised as a pseudo-video sequence. A comprehensive set of experiments has been conducted with the IST-EURECOM light field face database, for varied and challenging recognition tasks. Results show that the proposed framework achieves superior face recognition performance when compared to the state-of-the-art.","Title: A 4D DCT-Based Lenslet Light Field Codec\nYear: 2018\n\nAbstract: Light fields aim to represent visual information in 3D space. They are 4D structures that contain the images of a given scene from a sampled 2D range of viewpoints. When acquired using a lenslet camera, in addition to the ordinary intra-view redundancy, these views have a great deal of inter-view redundancy. In this work we propose a light field codec that fully exploits the 4D redundancy of light fields by using a 4D transform and hexadeca-trees. It initially divides the light field into 4D blocks and computes a 4D Discrete Cosine Transform of each one. Then the transform coefficients of the 4D block are grouped using hexadeca-trees on a bitplane-by-bitplane basis, and the generated stream is encoded using an adaptive arithmetic coder. The proposed codec has been employed to encode the JPEG Pleno lenslet light fields. The rate-distortion results have been assessed using test conditions comparable to the ones presented at the ICIP 2017 Light Field Coding Grand Challenge. The proposed codec, despite being conceptually simple, achieves competitive rate-distortion performance.","Title: Adoption Of Architecture Reference Models For Industrial Information Management Systems\nYear: 2018\n\nAbstract: Manufacturing is one of the European economy main pillar. Technological advances in fields such as computing, sensorisation, digitization, etc., changes in market behavior, value chains importance, brought new challenges to industrial production. Therefore, it requires the increase of flexibility, autonomy and adaptability of industrial systems and their interconnection to all other resources and integration into value chains. Those challenges are the main goal of Industry 4.0 vision. It emphasizes the idea of a total transformation of industrial production through the fusion of digital technology and the internet with the conventional industry; by digitally connect everything in and around the manufacturing operation. For that reason, it is crucial and urgent to prepare the national industry for this announced change, developing the knowledge, tools, and methods, to assist the manufacturing industry in the required digital transformation, to remain sustainable and competitive in the international context. In order to support manufacturing in the context of industry 4.0, the adoption of an architecture reference model is crucial, in order to allow the digital connection between all the manufacturing operations. However, there are several reference models proposed by different entities and industrial groups. The focus of this paper is to present our analysis of 14.0 reference models, RAMI4.0 and BRA, in order to contribute to the verification of the suitability of the combined use of those models to achieve an enriched Ho T ecosystem.","Title: Novel Long Short-Term Memory Cell Architectures: Application to Light Field Face Recognition.\nYear: 2019\n\nAbstract: With the emergence of lenslet light field cameras able to capture rich spatio-angular information from multiple directions, new frontiers in visual recognition performance have been opened. Since multiple 2D viewpoint images can be rendered from a light field, those multiple images, or descriptions extracted from them, can be organized as a pseudo-video sequence so that a LSTM network learns a model describing that sequence. This paper proposes three novel LSTM cell architectures able to create richer and more effective description models for visual recognition tasks, by jointly learning from two sequences simultaneously acquired. The novel key idea is to jointly process two sequences of rendered 2D images or their descriptions, e.g. representing the scene horizontal and vertical parallaxes, and thus with some specific dependency between them, that would not be exploited otherwise. To show the efficiency of the novel LSTM cell architectures, these architectures have been integrated into an end-to-end deep learning face recognition framework, which creates this join spatio-angular light field description. The LSTM network, using the proposed LSTM cell architectures, receives as input a sequence of VGG-Face descriptions computed for parallax related, horizontal and vertical 2D face viewpoint images, derived from the input light field image. A comprehensive evaluation in terms of recognition accuracy, computational complexity, memory efficiency, and parallelization ability has been performed with the IST EURECOM LFFD database using three new and challenging evaluation protocols. The obtained results show the superior performance of the proposed face recognition solutions adopting the novel LSTM cell architectures over ten state-of-the-art benchmarking recognition solutions.","Title: Novel Design of the Converter for an Active UPS Application Based on Marx Modulator Concept with Supercapacitors.\nYear: 2019\n\nAbstract: A new Marx modulator 4-leg multilevel converter is proposed to replace the well-known 4-leg inverter fed from batteries in Uninterruptible Power Supply (UPS) applications. The novel design concept for the Marx modulator based multilevel converter is presented and described. Each leg uses 2 Marx modulator modules, each one using an Electrochemical Double-Layer Capacitor (EDLC) (also known as supercapacitor (SC)) energy storage bank. The new topology concept enables multilevel operation with five voltage level per phase, allowing high quality voltage and current waveforms, distributed supercapacitor storage and reduction of supercapacitor bank voltage. The proposed converter can operate as UPS or as Active Power Filter (APF), powering non-linear or/and unbalanced loads, while balancing each leg supercapacitor voltage. A control strategy to choose the redundant vector configuration to balance the supercapacitor voltages is explained. Simulation results are presented for a Marx modulator based interactive 40 kVA UPS.","Title: A Point-to-Distribution Joint Geometry and Color Metric for Point Cloud Quality Assessment\nYear: 2021\n\nAbstract: Point clouds (PCs) are a powerful 3D visual representation paradigm for many emerging application domains, especially virtual and augmented reality, and autonomous vehicles. However, the large amount of PC data required for highly immersive and realistic experiences requires the availability of efficient, lossy PC coding solutions are critical. Recently, two MPEG PC coding standards have been deve...","Title: Joint Geometry and Color Projection-Based Point Cloud Quality Metric\nYear: 2022\n\nAbstract: Point cloud coding solutions have been recently standardized to address the needs of multiple application scenarios. The design and assessment of point cloud coding methods require reliable objective quality metrics to evaluate the level of degradation introduced by compression or any other type of processing. Several point cloud objective quality metrics have been recently proposed to reliably estimate human perceived quality, including the so-called projection-based metrics. In this context, this paper proposes a joint geometry and color projection-based point cloud objective quality metric which solves the critical weakness of this type of quality metrics, i.e., the misalignment between the reference and degraded projected images. Moreover, the proposed point cloud quality metric exploits the best performing 2D quality metrics in the literature to assess the quality of the projected images. The experimental results show that the proposed projection-based quality metric offers the best subjective-objective correlation performance in comparison with other metrics in the literature. The Pearson correlation gains regarding D1 -PSNR and D2-PSNR metrics range between similar to 5% to similar to 70% on three different datasets when data with all coding degradations is considered.","Title: Performance Evaluation of Objective Image Quality Metrics on Conventional and Learning-Based Compression Artifacts\nYear: 2021\n\nAbstract: Lossy image compression is a popular, simple and effective solution to reduce the amount of data representing digital pictures. In most lossy compression methods, the reduced volume of data in bits is achieved at the expense of introducing visual artifacts in the picture. The perceptual quality impact of such artifacts can be assessed with expensive and time-consuming subjective image quality expe...","Title: IMAGE CODING WITH NEURAL NETWORK-BASED COLORIZATION\nYear: 2021\n\nAbstract: Automatic colorization is a process with the objective of inferring the color of grayscale images. This process is frequently used for artistic purposes and to restore the color in old or damaged images. Motivated by the excellent results obtained with deep learning-based solutions in the area of automatic colorization, this paper proposes an image coding solution integrating a deep learning-based colorization process to estimate the chrominance components based on the decoded luminance which is regularly encoded with a conventional image coding standard. In this case, the chrominance components are not coded and transmitted as usual, notably after some subsampling, as only some color hints, i.e. chrominance values for specific pixel locations, may be sent to the decoder to help it creating more accurate colorizations. To boost the colorization and final compression performance, intelligent ways to select the color hints are proposed. Experimental results show performance improvements with the increased level of intelligence in the color hints extraction process and a good subjective quality of the final decoded (and colorized) images.","Title: An Introduction to the JPEG Fake Media Initiative\nYear: 2021\n\nAbstract: Recent advances in media creation and modification allow to produce near realistic media assets that are almost indistinguishable from original assets to the human eye. These developments open opportunities for creative production of new media in the entertainment and art industry. However, the intentional or unintentional spread of manipulated media, i.e., modified media with the intention to ind...","Title: Large-Scale Crowdsourcing Subjective Quality Evaluation of Learning-Based Image Coding\nYear: 2021\n\nAbstract: Learning-based image codecs produce different compression artifacts, when compared to the blocking and blurring degradation introduced by conventional image codecs, such as JPEG, JPEG 2000 and HEIC. In this paper, a crowdsourcing based subjective quality evaluation procedure was used to benchmark a representative set of end-to-end deep learning-based image codecs submitted to the MMSP'2020 Grand C...","Title: Deep Learning-based Point Cloud Coding for Immersive Experiences\nYear: 2022\n\nAbstract: ABSTRACTThe recent advances in visual data acquisition and consumption have led to the emergence of the so-called plenoptic visual models, where Point Clouds (PCs) are playing an increasingly important role. Point clouds are a 3D visual model where the visual scene is represented through a set of points and associated attributes, notably color. To offer realistic and immersive experiences, point clouds need to have millions, or even billions, of points, thus asking for efficient representation and coding solutions. This is critical for emerging applications and services, notably virtual and augmented reality, personal communications and meetings, education and medical applications and virtual museum tours. The point cloud coding field has received many contributions in recent years, notably adopting deep learning-based approaches, and it is critical for the future of immersive media experiences. In this context, the key objective of this tutorial is to review the most relevant point cloud coding solutions available in the literature with a special focus on deep learning-based solutions and its specific novel features. Special attention will be dedicated to the ongoing standardization projects in this domain, notably in JPEG and MPEG.","Title: A Framework Model to Support A/B Tests at the Class and Component Level\nYear: 2022\n\nAbstract: The amount of data collected from software use facilitated systematic inquiries about users' expectations and reactions to software systems. The most well-known practice for continuous experimentation is A/B tests, in which two or more versions of a feature are compared based on users' metrics when exposed to these options. The literature shows that A/B tests are spread in the industry, but companies usually rely on in-house software platforms based on traffic split. However, these approaches are better suitable for feature tests and not implementation options, besides increasing technical debt and maintenance effort. We aim to develop a model as a guide to frameworks for introducing experiments at class and component levels without coupling this concern to business rules. To reach this goal, we followed an iterative approach based on Design Science Research. In this process, we developed a reference implementation of this model by creating a framework for the Java language. We evaluated the experimentation framework usage in a web project that simulates a realistic scenario for applying A/B tests. The evaluation study showed that the framework provides the functional features needed to perform A/B tests at component and class level, collecting relevant information for decision-making. Moreover, it was possible to instantiate the framework without any coupling to code related to business rules. The proposed model could guide the development of experimentation frameworks that perform A/B tests at class and component levels, even for other languages and platforms. It captured the main elements of the experimentation domain, proposing appropriate extension points and a decoupled approach to be plugged into the application.","Title: Impact of Conventional and AI-based Image Coding on AI-based Face Recognition Performance\nYear: 2022\n\nAbstract: AI-based face recognition has become increasingly appealing for daily life applications due to its high performance. At the same time, image coding is very commonly used and, thus, many applications perform face recognition with decoded images. However, using decoded images, which may suffer from compression artifacts, may impact the final decision-making process of AI-based face recognition systems and, thus, its overall recognition performance. This paper studies the impact of image coding on the overall face verification performance of a popular and high performing face recognition solution, ArcFace. Face recognition using both original and decoded images, with several compression rates and qualities, is considered. Tests were performed using the Labeled Faces in the Wild (LFW) face dataset, with its images coded using conventional image coding standards, notably JPEG, JPEG 2000, and JPEG XL, as well as three emerging AI-based image codecs. As expected, the experimental results show that coding can have a significant impact on face recognition performance, with its impact becoming increasingly relevant as the coding rate is reduced. It is also observed that the recent AI-based image codecs appear to offer slightly better recognition performance for the same coding rates as a consequence of their better RD performance.","Title: Double-Deep Learning-Based Point Cloud Geometry Coding with Adaptive Super-Resolution\nYear: 2022\n\nAbstract: Point clouds represent 3D visual data in a very immersive and realistic way, offering to the users a large degree of navigation and interaction. For some key use cases, point clouds are potentially lighter and easier to acquire than other 3D representation models, thus offering an alternative with lower computational cost. To offer visual realistic and immersive experiences, notably the illusion of well-formed surfaces, point clouds typically require a large number of points. To make its storage and transmission feasible, efficient point cloud coding is essential. Recently, deep learning-based point cloud coding solutions have proven to be competitive in compression performance, excelling in distinct scenarios, although struggling to achieve similar results for sparser point clouds and lower coding rates. To tackle these limitations, this paper proposes a double-deep learning-based approach for point cloud coding by integrating a super-resolution tool. The main idea consists on converting sparser point clouds into denser ones via a down-sampling step performed before coding. Since this is a lossy process, a super-resolution step is included after decoding to mitigate the point losses and bringing the point cloud to the initial resolution. Furthermore, the sampling factor can be adaptively selected, thus offering additional flexibility to the point cloud characteristics. The proposed double-deep coding and super-resolution solution outperforms both the G-PCC Octree and V-PCC Intra point cloud coding standards achieving, respectively, 81.9% and 22.3% rate reduction measured as BD-Rate for the PSNR D1 metric."],"string":"[\n \"Title: The MPEG-21 Standard: Why an Open Multimedia Framework?\\nYear: 2001\\n\\nAbstract: MPEG [1] has been responsible for the successful MPEG-1 and MPEG-2 standards that have given rise to widely adopted commercial products and services, such as Video-CD, DVD, digital television, digital audio broadcasting (DAB) and MP3 (MPEG-1 Audio layer 3) players and recorders. More recently, the MPEG-4 standard [2] is aimed to define an audiovisual coding standard to address the emerging needs of the communication, interactive and broadcasting service models as well as of the mixed service models resulting from their technological convergence. The MPEG-4 object-based representation approach where a scene is modeled as a composition of objects, both natural and synthetic, with which the user may interact, is at the heart of the MPEG-4 technology. With this new coding approach, the MPEG-4 standard opens new frontiers in the way users will play with, create, re-use, access and consume audiovisual content. Following the same vision underpinning MPEG-4, MPEG initiated after another standardization project addressing the problem of describing multimedia content to allow the quick and efficient searching, processing and filtering of various types of multimedia material: MPEG-7 [3]. The need for a powerful solution for quickly and efficiently identifying, searching, filtering, etc., various types of multimedia content of interest to the user, human or machine, using also non text-based technologies, directly follows from the urge to efficiently use the available multimedia content and the difficulty of doing so.\",\n \"Title: Proposal for an Integrated Video Analysis Framework\\nYear: 1998\\n\\nAbstract: The analysis of video data targeting the identification of relevant objects and the extraction of associated descriptive characteristics will be the enabling factor for a number of multimedia applications. This process has intrinsic difficulties, and since semantic criteria are difficult to express, usually only a part of the desired analysis results can be automatically achieved. For many applications, the automatic tools can be complemented with user guidance to improve performance.This paper proposes an integrated framework for video analysis, addressing the video segmentation and feature extraction problems. The framework includes a set of modules that can be combined following specific application needs. It includes both automatic (more objective) and user interaction (more semantic) analysis modules. The paper also proposes a specific segmentation solution to one of the most relevant application scenarios considered - off-line applications requiring precise segmentation.\",\n \"Title: Motion compensated refinement for low complexity pixel based distributed video coding\\nYear: 2005\\n\\nAbstract: Distributed video coding (DVC) is a new coding paradigm that enables to exploit video statistics, partially or totally at the decoder. A particular case of DVC, Wyner-Ziv coding, deals with lossy source coding with side information at the decoder and allows a shift of complexity from the encoder to the decoder, theoretically without any penalty in the coding efficiency. The Wyner- Ziv solution here described encodes each video frame independently (intraframe coding), but decodes the same frame conditionally (interframe decoding). At the decoder, motion estimation and compensation tools are responsible to obtain an accurate interpolation of the original frame using previously decoded (temporally adjacent) frames. This paper proposes a novel approach to improve the performance of pixel domain Wyner-Ziv video coding by using a motion compensated refinement of the decoded frame and use it as improved side information. More precisely, upon partial decoding of each frame, the decoder refines its motion trajectories in order to achieve a better reconstruction of the decoded frame.\",\n \"Title: Posterior Sparsity in Unsupervised Dependency Parsing\\nYear: 2011\\n\\nAbstract: A strong inductive bias is essential in unsupervised grammar induction. In this paper, we explore a particular sparsity bias in dependency grammars that encourages a small number of unique dependency types. We use part-of-speech (POS) tags to group dependencies by parent-child types and investigate sparsity-inducing penalties on the posterior distributions of parent-child POS tag pairs in the posterior regularization (PR) framework of Graça et al. (2007). In experiments with 12 different languages, we achieve significant gains in directed attachment accuracy over the standard expectation maximization (EM) baseline, with an average accuracy improvement of 6.5%, outperforming EM by at least 1% for 9 out of 12 languages. Furthermore, the new method outperforms models based on standard Bayesian sparsity-inducing parameter priors with an average improvement of 5% and positive gains of at least 1% for 9 out of 12 languages. On English text in particular, we show that our approach improves performance over other state-of-the-art techniques.\",\n \"Title: Automatically annotating documents with normalized gene lists.\\nYear: 2005\\n\\nAbstract: Document gene normalization is the problem of creating a list of unique identifiers for genes that are mentioned within a document. Automating this process has many potential applications in both information extraction and database curation systems. Here we present two separate solutions to this problem. The first is primarily based on standard pattern matching and information extraction techniques. The second and more novel solution uses a statistical classifier to recognize valid gene matches from a list of known gene synonyms.We compare the results of the two systems, analyze their merits and argue that the classification based system is preferable for many reasons including performance, simplicity and robustness. Our best systems attain a balanced precision and recall in the range of 74%-92%, depending on the organism.\",\n \"Title: Optimized MVC Prediction Structures for Interactive Multiview Video Streaming.\\nYear: 2013\\n\\nAbstract: The Multiview Video Coding (MVC) standard efficiently compresses multiview video by considering spatial, temporal and interview correlations. This letter studies the impact of the MVC interview prediction structure on both the transmission and the overall coding rates for an interactive multiview video streaming system, considering both unicast and multicast scenarios, with the user interactive behavior represented by some view-popularity model. We propose a method to identify the optimal prediction structure minimizing the visual distortion, given some storage and link capacities constraints. Simulation results confirm that the optimal prediction structure results from a non-trivial tradeoff between the system constraints, the transmission model and the views' popularity.\",\n \"Title: Large-scale cross-document coreference using distributed inference and hierarchical models\\nYear: 2011\\n\\nAbstract: Cross-document coreference, the task of grouping all the mentions of each entity in a document collection, arises in information extraction and automated knowledge base construction. For large collections, it is clearly impractical to consider all possible groupings of mentions into distinct entities. To solve the problem we propose two ideas: (a) a distributed inference technique that uses parallelism to enable large scale processing, and (b) a hierarchical model of coreference that represents uncertainty over multiple granularities of entities to facilitate more effective approximate inference. To evaluate these ideas, we constructed a labeled corpus of 1.5 million disambiguated mentions in Web pages by selecting link anchors referring to Wikipedia entities. We show that the combination of the hierarchical model with distributed inference quickly obtains high accuracy (with error reduction of 38%) on this large dataset, demonstrating the scalability of our approach.\",\n \"Title: A State-Space Based Model-Checking Framework for Embedded System Controllers Specified Using IOPT Petri Nets.\\nYear: 2012\\n\\nAbstract: This paper presents a state-space based model-checking framework to test and validate embedded system controllers specified using the [OPT Petri net formalism. The framework is composed of an automatic software code generator, a state-space generator and a query engine, used to define queries applied to the resulting state-space graphs. During state-space generation, the tools collect information required to enable the efficient implementation of hardware/software controllers, including place bounds, deadlocks and conflicts between concurrent transitions. User defined queries can check relevant system properties, as the occurrence of undesired error situations, the reachability of desired states, system liveliness and the occurrence of deadlocks and livelocks. The new tool, available online under a Web based user interface, provides a fast and efficient way to test and validate system controllers, contributing to the reduction of development time.\",\n \"Title: Side information creation for efficient Wyner-Ziv video coding: Classifying and reviewing\\nYear: 2013\\n\\nAbstract: Video coding technologies have played a major role in the explosion of large market digital video applications and services. In this context, the very popular MPEG-x and H-26x video coding standards adopted a predictive coding paradigm, where complex encoders exploit the data redundancy and irrelevancy to 'control' much simpler decoders. This codec paradigm fits well applications and services such as digital television and video storage where the decoder complexity is critical, but does not match well the requirements of emerging applications such as visual sensor networks where the encoder complexity is more critical. The Slepian-Wolf and Wyner-Ziv theorems brought the possibility to develop the so-called Wyner-Ziv video codecs, following a different coding paradigm where it is the task of the decoder, and not anymore of the encoder, to (fully or partly) exploit the video redundancy. Theoretically, Wyner-Ziv video coding does not incur in any compression performance penalty regarding the more traditional predictive coding paradigm (at least for certain conditions). In the context of Wyner-Ziv video codecs, the so-called side information, which is a decoder estimate of the original frame to code, plays a critical role in the overall compression performance. For this reason, much research effort has been invested in the past decade to develop increasingly more efficient side information creation methods. This paper has the main objective to review and evaluate the available side information methods after proposing a classification taxonomy to guide this review, allowing to achieve more solid conclusions and better identify the next relevant research challenges. After classifying the side information creation methods into four classes, notably guess, try, hint and learn, the review of the most important techniques in each class and the evaluation of some of them leads to the important conclusion that the side information creation methods provide better rate-distortion (RD) performance depending on the amount of temporal correlation in each video sequence. It became also clear that the best available Wyner-Ziv video coding solutions are almost systematically based on the learn approach. The best solutions are already able to systematically outperform the H.264/AVC Intra, and also the H.264/AVC zero-motion standard solutions for specific types of content.\",\n \"Title: Distributed video coding: Selecting the most promising application scenarios\\nYear: 2008\\n\\nAbstract: Distributed Video Coding (DVC) is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Recently, practical DVC solutions have been proposed with promising results; however, there is still a need to study in a more systematic way the set of application scenarios for which DVC may bring major advantages. This paper intends to contribute for the identification of the most DVC friendly application scenarios, highlighting the expected benefits and drawbacks for each studied scenario. This selection is based on a proposed methodology which involves the characterization and clustering of the applications according to their most relevant characteristics, and their matching with the main potential DVC benefits.\",\n \"Title: Binary tree decomposition depth coding for 3D video applications\\nYear: 2011\\n\\nAbstract: Recent advances in three dimensional display technologies and the growing efforts put in the production of three dimensional videos are intensely demanding for new, more efficient three dimensional content representation formats. One promising for mat is the so-called multiview plus depth format where multiple views of the observed scene are represented together with a per pixel depth map. Naturally, this format requires to efficiently code not only the video views but also the depth data. In this context, this paper proposes a novel depth map codec encoding the depth data by means of a binary tree triangular decomposition and reconstructing the depth map values by means of a tri angle based planar approximation. For depth maps related to typical three dimensional video contents, the proposed depth map codec outperforms both the H.264/AVC standard with all intra coding modes enabled and the JPEG standard. In particular, for the same objective reconstruction quality, the proposed codec allows an average bitrate reduction of 60% and 90% regarding H.264/AVC Intra and JPEG coding, respectively.\",\n \"Title: Stand-alone objective segmentation quality evaluation\\nYear: 2002\\n\\nAbstract: The identification of objects in video sequences, that is, video segmentation, plays a major role in emerging interactive multimedia services, such as those enabled by the ISO MPEG-4 and MPEG-7 standards. In this context, assessing the adequacy of the identified objects to the application targets, that is, evaluating the segmentation quality, assumes a crucial importance. Video segmentation technology has received considerable attention in the literature, with algorithms being proposed to address various types of applications. However, the segmentation quality performance evaluation of those algorithms is often ad hoc, and a well-established solution is not available. In fact, the field of objective segmentation quality evaluation is still maturing; recently, some more efforts have been made, mainly following the emergence of the MPEG object-based coding and description standards. This paper discusses the problem of objective segmentation quality evaluation in its most difficult scenario: stand-alone evaluation, that is when a reference segmentation is not available for comparative evaluation. In particular, objective metrics are proposed for the evaluation of stand-alone segmentation quality for both individual objects and overall segmentation partitions.\",\n \"Title: Advanced side information creation techniques and framework for Wyner-Ziv video coding\\nYear: 2008\\n\\nAbstract: Recently, several distributed video coding (DVC) solutions based on the distributed source coding (DSC) paradigm have appeared in the literature. Wyner-Ziv (WZ) video coding, a particular case of DVC where side information is made available at the decoder, enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill novel requirements from applications such as video surveillance, sensor networks and mobile camera phones. The quality of the side information at the decoder has a critical role in determining the WZ video coding rate-distortion (RD) performance, notably to raise it to a level as close as possible to the RD performance of standard predictive video coding schemes. Towards this target, efficient motion search algorithms for powerful frame interpolation are much needed at the decoder. In this paper, the RD performance of a Wyner-Ziv video codec is improved by using novel, advanced motion compensated frame interpolation techniques to generate the side information. The development of these type of side information estimators is a difficult problem in WZ video coding, especially because the decoder only has available some reference, decoded frames. Based on the regularization of the motion field, novel side information creation techniques are proposed in this paper along with a new frame interpolation framework able to generate higher quality side information at the decoder. To illustrate the RD performance improvements, this novel side information creation framework has been integrated in a transform domain turbo coding based Wyner-Ziv video codec. Experimental results show that the novel side information creation solution leads to better RD performance than available state-of-the-art side information estimators, with improvements up to 2dB; moreover, it allows outperforming H.264/AVC Intra by up to 3dB with a lower encoding complexity.\",\n \"Title: Exploiting Feature Covariance in High-Dimensional Online Learning\\nYear: 2010\\n\\nAbstract: Some online algorithms for linear classifica- tion model the uncertainty in their weights over the course of learning. Modeling the full covariance structure of the weights can provide a significant advantage for classifica- tion. However, for high-dimensional, large- scale data, even though there may be many second-order feature interactions, it is com- putationally infeasible to maintain this co- variance structure. To extend second-order methods to high-dimensional data, we de- velop low-rank approximations of the covari- ance structure. We evaluate our approach on both synthetic and real-world data sets us- ing the confidence-weighted (Dredze et al., 2008; Crammer et al., 2009a) online learning framework. We show improvements over di- agonal covariance matrices for both low and high-dimensional data.\",\n \"Title: Weakly-supervised acquisition of labeled class instances using graph random walks\\nYear: 2008\\n\\nAbstract: We present a graph-based semi-supervised label propagation algorithm for acquiring open-domain labeled classes and their instances from a combination of unstructured and structured text sources. This acquisition method significantly improves coverage compared to a previous set of labeled classes and instances derived from free text, while achieving comparable precision.\",\n \"Title: Visual interactive subgroup discovery with numerical properties of interest\\nYear: 2006\\n\\nAbstract: We propose an approach to subgroup discovery using distribution rules (a kind of association rules with a probability distribution on the consequent) for numerical properties of interest. The objective interest of the subgroups is measured through statistical goodness of fit tests. Their subjective interest can be assessed by the data analyst through a visual interactive subgroup browsing procedure.\",\n \"Title: Hierarchical motion estimation for side information creation in Wyner-Ziv video coding\\nYear: 2008\\n\\nAbstract: Recently, several video coding solutions based on the distributed source coding paradigm have appeared in the literature. Among them, Wyner-Ziv video coding schemes enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill requirements of emerging applications such as visual sensor networks and wireless surveillance. To achieve a performance comparable to the predictive video coding solutions, it is necessary to increase the quality of the side information, this means the estimation of the original frame created at the decoder. In this paper, a hierarchical motion estimation (HME) technique using different scales and increasingly smaller block sizes is proposed to generate a more reliable estimation of the motion field. The HME technique is integrated in a well known motion compensated frame interpolation framework responsible for the creation of the side information in a Wyner-Ziv video decoder. The proposed technique enables to achieve improvements in the rate-distortion (RD) performance up to 7 dB when compared to H.263+ Intra and 3 dB when compared to H.264/AVC Intra.\",\n \"Title: Dynamic quality control for transform domain Wyner-Ziv video coding\\nYear: 2009\\n\\nAbstract: Wyner-Ziv is an emerging video coding paradigm based on the Slepian-Wolf and Wyner-Ziv theorems where video coding may be performed by exploiting the temporal correlation at the decoder and not anymore at the encoder as in conventional video coding. This approach should allow designing low-complexity encoders, targeting important emerging applications such as wireless surveillance and visual sensor networks, without any cost in terms of RD performance. However, the currently available WZ video codecs do not allow controlling the target quality in an efficient way which is a major limitation for some applications. In this context, the main objective of this paper is to propose an efficient quality control algorithm to maintain a uniform quality along time in low-encoding complexity WZ video coding by dynamically adapting the quantization parameters depending on the desired target quality without any a priori knowledge about the sequence characteristics. This objective will be reached in the context of the so-called Stanford WZ video codec architecture which is currently the most used in the literature.\",\n \"Title: Multiple UAV teams for multiple tasks.\\nYear: 2009\\n\\nAbstract: In a search and prosecute mission, multiple heterogeneous unmanned aerial vehicles UAVs that carry different resources need to perform the classify, prosecute and battle damage assessment (BDA) tasks on targets sequentially. Depending on the target resource requirement, it may be necessary to deploy a coalition of UAVs to perform the action. In this paper, we propose coalition formation algorithms that have low computational overhead to determine coalitions for the prosecute and the BDA tasks. We also develop a simultaneous strike mechanism based on Dubins curves for the UAVs to prosecute the target simultaneously. Monte-Carlo simulation results are presented to show how the algorithms work and the effect of increasing the number of BDA tasks on the mission performance.\",\n \"Title: Drift Reduction For A H.264/Avc Fine Grain Scalability With Motion Compensation Architecture\\nYear: 2004\\n\\nAbstract: The recent advances in non-scalable video encoding brought by the H.264/AVC standard offered significant improvements in tenus of rate-distortion performance. This paper proposes a H.264/AVC based fine grain scalable video encoder which also exploits the motion compensation tools of the H.264/AVC standard to explore the temporal redundancy in the enhancement layer. The enhancement layer is predicted from a high quality reference obtained from past information of the enhancement and base layers. One of the drawbacks of this architecture is the drift effect., which occurs when part of the enhancement layer used for prediction is not received by the decoder. The drift reduction approaches here proposed simultaneously allow improvements in the coding efficiency and a reduction of the drift effect. The experimental results show improvements LIP to 2 dB in coding efficiency in comparison to Intra coding (like used by the MPEG-4 FGS standard) using the MPEG-4 testing conditions.\",\n \"Title: Integrating low-level and semantic visual cues for improved image-to-video experiences\\nYear: 2006\\n\\nAbstract: Nowadays, the heterogeneity of networks, terminals, and users is growing. At the same time, the availability and usage of multimedia content is increasing, which has raised the relevance of content adaptation technologies able to fulfill the needs associated to all usage conditions. For example, mobile displays tend to be too small to allow one to see all the details of an image. This paper presents an innovative method to integrate low-level and semantic visual cues into a unique visual attention map that represents the most interesting contents of an image, allowing the creation of a video sequence that browses through the image displaying its regions of interest in detail. The architecture of the developed adaptation system, the processing solutions and also the principles and reasoning behind the algorithms that have been developed and implemented are presented in this paper. Special emphasis is given to the integration of low-level and semantic visual cues for the maximization of the image to video adapted experience.\",\n \"Title: Refreshment need metrics for improved shape and texture object-based resilient video coding\\nYear: 2003\\n\\nAbstract: Video encoders may use several techniques to improve error resilience. In particular, for video encoders that rely on predictive (inter) coding to remove temporal redundancy, intra coding refreshment is especially useful to stop error propagation when errors occur in the transmission or storage of the coded streams, which can cause the decoded quality to decay very rapidly. In the context of object-based video coding, the video encoder can apply intra coding refreshment to both the shape and the texture data. In this paper, shape refreshment need and texture refreshment need metrics are proposed which can be used by object-based video encoders, notably MPEG-4 video encoders, to determine when the shape and the texture of the various video objects in the scene should be refreshed in order to improve the decoded video quality, e.g., for a given bit rate.\",\n \"Title: Temporal shape error concealment by global motion compensation with local refinement\\nYear: 2006\\n\\nAbstract: This paper presents an original temporal shape error concealment technique based on a combination of global and local motion compensation. For this technique, which is especially useful for object-based video applications in error-prone environments (e.g., mobile networks), it is assumed that the shape of the corrupted object at hand is in the form of a binary alpha plane and some of the shape data is missing due to channel errors. To conceal the corrupted shape, the decoder first assumes that a global motion model can describe the shape changes in consecutive time instants. This way, based on locally estimated global motion parameters, the decoder attempts to conceal the corrupted alpha plane by global motion compensating the shape data from the previous time instant. Afterwards, since a global motion model cannot perfectly describe all alpha plane changes, a local motion refinement is applied to improve the concealment in areas of the object with significant local motion.\",\n \"Title: Reply Expectation Prediction for Email Management\\nYear: 2005\\n\\nAbstract: We reduce email overload by addressing the problem of waiting for a reply to one's email. We predict whether sent and received emails necessitate a reply, enabling the user to both better manage his inbox and to track mail sent to others. We discuss the features used to discriminate emails, show promising initial results with a logistic regression model, and outline future directions for this work.\",\n \"Title: Cell loss resilience for B-ISDN video communications\\nYear: 1992\\n\\nAbstract: The increasing interest in video services is giving a new push for a network able to satisfy broadband services demand: the Broadband Integrated Services Digital Network directed to the support of a wide range of services in the same universal network. This network uses the Asynchronous Transfer Mode (ATM) based on the concept of packet transmission which enables variable bit rate information flows. The application of the variable bit rate capability to video coding opened new horizons to video communications among which the constant quality video coding assumes particular interest. This paper deals with the cell loss phenomenon which is a kind of degradation of information typical of ATM environments, and presents some cell loss recovering techniques as well as simulation results for video communications.\",\n \"Title: The ORCHESTRA Collaborative Data Sharing System\\nYear: 2008\\n\\nAbstract: Sharing structured data today requires standardizing upon a single schema, then mapping and cleaning all of the data. This results in a single queriable mediated data instance. However, for settings in which structured data is being collaboratively authored by a large community, e.g., in the sciences, there is often a lack of consensus about how it should be represented, what is correct, and which sources are authoritative. Moreover, such data is seldom static: it is frequently updated, cleaned, and annotated. The ORCHESTRA collaborative data sharing system develops a new architecture and consistency model for such settings, based on the needs of data sharing in the life sciences. In this paper we describe the basic architecture and implementation of the ORCHESTRA system, and summarize some of the open challenges that arise in this setting.\",\n \"Title: The design principles of a weighted finite-state transducer library\\nYear: 2000\\n\\nAbstract: We describe the algorithmic and software design principles of an object-oriented library for weighted finite-state transducers. By taking advantage of the theory of rational power series, we were able to achieve high degrees of generality, modularity and irredundancy, while attaining competitive efficiency in demanding speech processing applications involving weighted automata of more than 10 7 states and transitions. Besides its mathematical foundation, the design also draws from important ideas in algorithm design and programming languages: dynamic programming and shortest-paths algorithms over general semirings, object-oriented programming, lazy evaluation and memoization.\",\n \"Title: Low delay distributed video coding with refined side information\\nYear: 2011\\n\\nAbstract: Distributed video coding (DVC) is a new video coding paradigm based upon two fundamental theoretical results: the Slepian-Wolf and Wyner-Ziv theorems. Among other benefits, this new coding paradigm may allow a flexible complexity allocation between the encoder and the decoder. Several DVC codecs have been developed over the years addressing the specific requirements of emerging applications such as wireless video surveillance and sensor networks. While state-of-the-art DVC codecs, such as the DISCOVER DVC codec, have shown promising RD performance, most DVC codecs in the literature do not consider low delay requirements which are relevant for some of the addressed applications. In this context, the main objective and novelty of this paper is to propose an efficient, low delay and fully practical DVC codec based on the Stanford DVC architecture adopting a side information iterative refinement approach. The obtained performance results show that the developed DVC solution fulfils the objectives regarding relevant benchmarks, notably due to the novel side information creation and correlation noise modeling tools integrated in a side information iterative refinement framework.\",\n \"Title: Low complexity intra mode selection for efficient distributed video coding\\nYear: 2009\\n\\nAbstract: Motion compensated frame interpolation (MCFI) is one of the most efficient solutions to generate side information (SI) in the context of distributed video coding. However, it creates SI with rather significant motion compensated errors for some frame regions while rather small for some other regions depending on the video content. In this paper, a low complexity Intra mode selection algorithm is proposed to select the most 'critical' blocks in the WZ frame and help the decoder with some reliable data for those blocks. For each block, the novel coding mode selection algorithm estimates the encoding rate for the Intra based and WZ coding modes and determines the best coding mode while maintaining a low encoder complexity. The proposed solution is evaluated in terms of rate-distortion performance with improvements up to 1.2 dB regarding a WZ coding mode only solution.\",\n \"Title: Error resilience and concealment performance for MPEG-4 frame-based video coding\\nYear: 1999\\n\\nAbstract: This paper addresses the general problem of error resilience and concealment in the context of content-based video coding schemes, such as the new MPEG-4 video coding standard. In the first part of the paper, the most important error resilience tools available in the literature are studied, organized and classified according to three main classes, notably: error resilient source coding, channel coding and decoding, and error concealment. In the second part, the performance of the MPEG-4 error resilient frame-based syntax, which addresses simple mobile communications, is studied with a meaningful set of test conditions and three different concealment schemes. (C) 1999 Elsevier Science B.V. All rights reserved.\",\n \"Title: Finite-state approximations of grammars\\nYear: 1990\\n\\nAbstract: Grammars for spoken language systems are subject to the conflicting requirements of language modeling for recognition and of language analysis for sentence interpretation. Current recognition algorithms can most directly use finite-state acceptor (FSA) language models. However, these models are inadequate for language interpretation, since they cannot express the relevant syntactic and semantic regularities. Augmented phrase structure grammar (APSG) formalisms, such as unification grammars, can express many of those regularities, but they are computationally less suitable for language modeling, because of the inherent cost of computing state transitions in APSG parsers.\",\n \"Title: Controlling complexity in part-of-speech induction\\nYear: 2011\\n\\nAbstract: We consider the problem of fully unsupervised learning of grammatical (part-of-speech) categories from unlabeled text. The standard maximum-likelihood hidden Markov model for this task performs poorly, because of its weak inductive bias and large model capacity. We address this problem by refining the model and modifying the learning objective to control its capacity via parametric and non-parametric constraints. Our approach enforces word-category association sparsity, adds morphological and orthographic features, and eliminates hard-to-estimate parameters for rare words. We develop an efficient learning algorithm that is not much more computationally intensive than standard training. We also provide an open-source implementation of the algorithm. Our experiments on five diverse languages (Bulgarian, Danish, English, Portuguese, Spanish) achieve significant improvements compared with previous methods for the same task.\",\n \"Title: Evaluating a feedback channel based transform domain Wyner-Ziv video codec\\nYear: 2008\\n\\nAbstract: Wyner-Ziv (WZ) video coding-a particular case of distributed video coding (DVC)-is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. In recent years, some practical WZ video coding solutions have been proposed with promising results. One of the most popular WZ video coding architectures in the literature uses turbo codes based Slepian-Wolf coding and a feedback channel to perform rate control at the decoder. This WZ video coding architecture has been first proposed by researchers at Stanford University and has been after adopted and improved by many research groups around the world. However, while there are many papers published with changes and improvements to this architecture, the precise and detailed evaluation of its performance, targeting its deep understanding for future advances, has not been made. Available performance results are mostly partial, under unclear and incompatible conditions, using vaguely defined and also sometimes architecturally unrealistic codec solutions. This paper targets the provision of a detailed, clear, and complete performance evaluation of an advanced transform domain WZ video codec derived from the Stanford turbo coding and feedback channel based architecture. Although the WZ video codec proposed for this evaluation is among the best available, the main purpose and novelty of this paper is the solid and comprehensive performance evaluation made which will provide a strong, and very much needed, performance reference for researchers in this WZ video coding field, as well as a solid way to steer future WZ video coding research.\",\n \"Title: A Deductive Account of Quantification in LFG.\\nYear: 1994\\n\\nAbstract: The relationship between Lexical-Functional Grammar (LFG) functional\\nstructures (f-structures) for sentences and their semantic interpretations can\\nbe expressed directly in a fragment of linear logic in a way that explains\\ncorrectly the constrained interactions between quantifier scope ambiguity and\\nbound anaphora. The use of a deductive framework to account for the\\ncompositional properties of quantifying expressions in natural language\\nobviates the need for additional mechanisms, such as Cooper storage, to\\nrepresent the different scopes that a quantifier might take. Instead, the\\nsemantic contribution of a quantifier is recorded as an ordinary logical\\nformula, one whose use in a proof will establish the scope of the quantifier.\\nThe properties of linear logic ensure that each quantifier is scoped exactly\\nonce. Our analysis of quantifier scope can be seen as a recasting of Pereira's\\nanalysis (Pereira, 1991), which was expressed in higher-order intuitionistic\\nlogic. But our use of LFG and linear logic provides a much more direct and\\ncomputationally more flexible interpretation mechanism for at least the same\\nrange of phenomena. We have developed a preliminary Prolog implementation of\\nthe linear deductions described in this work.\",\n \"Title: A tool for interactive subgroup discovery using distribution rules\\nYear: 2007\\n\\nAbstract: We describe an approach and a tool for the discovery of subgroups within the framework of distribution rule mining. Distribution rules are a kind of association rules particularly suited for the exploratory study of numerical variables of interest. Being an exploratory technique, the result of a distribution mining process is typically a very large number of patterns. Exploring such results is thus a complex task and limits the use of the technique. To overcome this shortcoming we developed a tool, written in Java, which supports subgroup discovery in a post-processing step. The tool engages the analyst in an interactive process of subgroup discovery by means of a graphical interface with well defined statistical grounds, where domain knowledge can be used during the identification of such subgroups amid the population. We show a case study to analyze the results of students in a large scale university admission examination.\",\n \"Title: Minimalist Architecture to Generate Embedded System Web User Interfaces.\\nYear: 2013\\n\\nAbstract: This paper presents a new architecture to. semi-automatically generate Web user interfaces for Embedded Systems designed using IOPT Petri Net models. The user interfaces can be used to remotely control, monitor and debug embedded systems using a standard Web Browser. The proposed architecture takes advantage of the distributed nature of the Internet to store all static user interface data and software on third-party Web services (the Cloud), and execute the user-interface code on the user's Web Browser. A simplified protocol is proposed to enable remote control, status-monitoring, debugging and step-by-step execution, minimizing resource consumption on the physical embedded devices, including processing load, memory and communication bandwidth. As the user interface data and code are kept on third-party Web services, these resources can be shared among multiple embedded device units, and the hardware requirements to implement the devices can be simplified, leading to reduced cost solutions. To prevent down-time due to network problems or server failures, a fault-tolerant topology is suggested. The distributed architecture is transparent to end-users, observing just a Web interface for an embedded device on the other side of an Internet URL.\",\n \"Title: Reading the web with learned syntactic-semantic inference rules\\nYear: 2012\\n\\nAbstract: We study how to extend a large knowledge base (Freebase) by reading relational information from a large Web text corpus. Previous studies on extracting relational knowledge from text show the potential of syntactic patterns for extraction, but they do not exploit background knowledge of other relations in the knowledge base. We describe a distributed, Web-scale implementation of a path-constrained random walk model that learns syntactic-semantic inference rules for binary relations from a graph representation of the parsed text and the knowledge base. Experiments show significant accuracy improvements in binary relation prediction over methods that consider only text, or only the existing knowledge base.\",\n \"